[0001] This application claims priority of the provisional application of Ser. No. 60/139,096
filed June 14, 1999 entitled "Stretch Break Method and Product".
FIELD OF INVENTION
[0002] This invention relates generally to a fiber conversion and spinning process, and
more particularly concerns methods for stretch-breaking continuous filament fibers
to form discontinuous filament fibers and consolidating these fibers into yarns.
BACKGROUND
[0003] Spun yarns of synthetic staple fibers have been produced by cutting continuous filaments
into staple fibers, which are then assembled into individual yarn in the same manner
as fibers of cotton or wool. A simpler direct spinning process is also used wherein
parallel continuous filaments are stretch-broken and drafted between input rolls and
delivery rolls in what is sometimes called a stretch break zone or a draft cutting
zone to form a sliver of discontinuous fibers which is thereafter twisted to form
a spun yarn as disclosed, for example, in US 2,721,440 to New or US 2,784,458 to Preston.
Such early processes were slow due to the inherent speed limitations of a true twisting
device. As an alternative to true twisting, Bunting et al in US 3,110,151 discloses
consolidating staple fibers to make a yarn product using an entangling, or interlacing,
jet device for entangling into yarn. Such a product can be produced faster than true
twisting, but is not comparable to conventional spun yarns in strength, cleanness,
and uniformity. Alternatively, US 4,080,778 to Adams et al discloses a process where
a 1500-5000 denier tow of continuous filaments may be heated and drawn, and is then
stretch-broken and drafted in a single zone and exits at high speed through an apertured
draft roll and an aspirator to maintain co-current flow of fluid and fiber through
the roll nip. The discontinuous, unconsolidated filaments are then consolidated in
an entangling jet of a type disclosed in Bunting to make a yarn of 50-300 denier.
Static charges are removed in the stretch-breaking and drafting zone to minimize splaying.
Static removal devices are also placed adjacent the roll pairs that forward the filaments
through the process. About 1.5-20% of the discontinuous filaments produced in the
stretch-breaking zone exceeds 76 cm in length. The yarn axis is required to be vertical
throughout the process. The resultant product is a consolidated yarn with excellent
strength, generally higher than ring-spun yarns, which is slub-free and clean.
[0004] Multiple stretch-break zones are taught in US 4,924,556 to Gilhaus for progressively
reducing the discontinuous filament length for large denier tows which are built up
from combining several low weight tows over tensioning guide bars and guiding members.
In this way distortions of less than 4.5 can be run with low weight feed tows and
production capacity remains high. The combined tows are drawn without breaking in
a distortion and heating zone (zone I) at one horizontal level and then passed sequentially
through one or more progressively shorter, stretch-breaking zones, (zones II-V) arranged
horizontally in another level to conserve floor space. The stretch-breaking zones
may comprise one or more "preliminary" breaking zones that progressively shorten the
fibers, and one or more breaking zones that set the average fiber length and set the
variability of fiber length (%CV). The sliver formed may be processed in an entwining
mechanism (to facilitate subsequent handling), heat treated, and collected in a canister.
It is expected that the sliver would be further processed, as in a spinning machine,
to produce small denier yarns. The process handles feed tows of 3.0 denier per filament
and 110,000 - 220,000 denier, and in a band having a width greater than 270 mm in
the drawing and breaking zones. In the example illustrated in Fig. 1, a first preliminary
breaking zone, zone II, is at least 500 mm long and the filament lengths resulting
from this zone have a "nearly normal distribution" of fiber lengths between a few
millimeters and the length of zone II. The zone II length is an optimization between
a longer length, which reduces the breaking forces, and a shorter length, which avoids
floc breaks and improves operating conditions. There is a second preliminary breaking
zone, zone III, which is at least 200 mm and less than 1000 mm which is "considerably
shorter" than zone II. There is then a first breaking zone, zone IV, which sets the
average fiber length and appears shorter than zone III; and a second breaking zone,
zone V, which eliminates overly long fibers, sets the variations in fiber length (characterized
by %CV), and appears shorter than zone IV. In zone V, the "breaking distortions" (believed
to be speed ratios) are at least 2X those in zone IV.
[0005] A horizontal in-line process for making a fasciated yarn from a tow of fibers is
taught by Minorikawa et al in U.S. 4,667,463. The process involves drawing the tow
over a heater in an elongated area having a narrow width, draft cutting the tow, and
subjecting the draft cut fibers to an amendatory draft cutting step and a yarn formation
step. The length of the zone in the amendatory draft cutting step is about 0.4 to
0.9 times the length of the draft cutting zone and the draw ratio for the amendatory
draft cutting is at least 2.5x. The drawing preferably occurs in two stages to achieve
a draw ratio of 90-99% of the maximum draw ratio and the drawn fiber is then heat
treated. The yarn formation step uses a jet system for consolidating the fibers by
creating wrapper fibers around the fiber core and wrapping them around the core fibers.
Occasionally, apron bands are used in the amendatory draft cutting zone and yarn formation
zone to regulate the peripheral fibers. The product is described in U.S. 4,356,690
to Minorikawa et al as being characterized by the fact that more than about 15% of
the filaments in the yarn have a filament length of less than 0.5 times the average
filament length of the yarn and more than about 15% of the filaments in the yarn have
a filament length greater than 1.5 times the average filament length of the yarn.
In the examples shown, the maximum output speed of the process making yarns of 174
to 532 denier (30.5 to 10 cotton count) is 200 meters/minute (ex. 6) with most examples
run at about 100 meters/minute.
[0006] There is a problem with the products produced by Adams et al in that the 1.5-20%
of the discontinuous filaments exceeding 76 cm in length that are produced in the
single stretch-breaking zone cause problems in further processing (primarily roll
wraps) especially if a non-vertical process orientation is chosen. There is also a
problem with long filaments in the product of Adams in that it limits the number of
filament ends that are available to protrude from the yarn and provide a yarn with
a comfortable feel and look for textile applications.
[0007] In the case of Gilhaus' horizontal orientation, it may only be easily applied to
processing large tows where it is believed the large number of filaments contribute
to good intra-bundle friction between discontinuous filaments so bundle integrity
can be maintained in the process without difficulty. In the case of Adams, the small
numbers of filaments in the unconsolidated discontinuous yarn provide little frictional
cohesion. A vertical orientation is believed required to eliminate lateral forces
on the delicate yarn due to gravity before consolidation strengthens the yarn.
[0008] Adams proposes doing all stretch breaking in one zone and any drafting of the yarn
in the same zone. Such a multipurpose zone makes independent optimization of final
yarn parameters difficult or impossible.
[0009] Minorikawa et al may have a problem controlling discontinuous filaments as evidenced
by the use of apron bands. This lack of control and the use of apron bands may limit
the speed of his process to that disclosed in his examples which at 200 m/min is too
slow for commercial production of a single low denier yarn line.
[0010] There is a need for an improved process for producing a stretch-broken yarn where
the operating parameters can be independently optimized, where the process is not
constrained to operate in a vertical orientation, and where excessively long filaments
are not present that may separate from the filament bundle and wrap in the processing
equipment and limit the number of filament ends in the yarn. There is a need for a
process that can operate robustly and at a high speed above 250 m/min to make production
of one yarn line at a time directly from tow economically attractive.
SUMMARY OF THE INVENTION
[0011] Applicants have developed a process that produces a small denier, discontinuous filament
yarn with filament lengths shorter than about 64 cm (25 in) that results in a high
number of filament ends per inch from continuous filament feed yarn. The new process
operates at rates that make production of individual yarns commercially feasible.
The production rates greatly exceed those of ring spun staple yarns that traditionally
have a high number of filament ends per inch. The process permits operation in either
a vertical or horizontal orientation without sacrificing runnability. The process
is adaptable to a variety of continuous filament yarn polymers and for blending dissimilar
continuous filament yarns. In preferred embodiments, the process utilizes at least
two break zones for obtaining the preferred filament lengths in the final yarn product
having an average filament length greater than 6.0 inches and the speed ratio D1 of
the first break zone and the speed ratio D2 of the second break zone should be at
a level of at least 2.0. In addition, a relationship L2/L1 between the second break
zone length L2 and the first break zone length L1, is constrained to be in a range
of 0.2 to 0.6 to achieve the desired overall filament lengths, length distribution,
and good system operability. Following the break zones, there is a consolidation zone
for consolidating the discontinuous filaments in the yarn and intermingling them by
any of a variety of means to maintain unity of the yarn. The process includes improvements
to systems having one or more stretch break zones.
[0012] One feature of the new process is based on the belief that it is important to arrange
for some "double gripped" filaments throughout the stretch-break and drafting process.
Double-gripped filaments are those that are long enough to span the distance between
two roll sets for each stretch breaking and drafting zone. Double-gripped filaments
provide some support for the other filaments so there is good cohesion of the filament
bundle in each zone that aids runnability, especially when making low denier yarns
with few filaments. If low speed ratios are utilized in the break zones, this is believed
to result in more long filaments that can serve as double-gripped filaments, but this
requires more break zones to achieve a high overall speed ratio to improve productivity.
It also results in more zones required to reduce the filament lengths to a low level
that is desirable for producing yarns with a large number of filament ends. Protruding
filament ends are believed to give the yarn a better feel, or "hand". Applicants have
discovered there is a preferred operating process for optimizing machine runnability
when making small denier yarns with shorter fibers to optimize the filament ends per
inch. To enhance productivity, the overall speed ratio of the process must remain
high and the speed ratio increase must be shared by at least two break zones while
maximizing the runnability which requires maintaining a certain minimum proportion
of double gripped fibers in each zone. Applicants have discovered that to produce
a desirable product certain process parameters must be carefully controlled. The relationship
of speed ratio D1 of the first break zone being ≥ 2.0 and the speed ratio D2 of the
second break zone being ≥ 2.0 should also preferably satisfy the following equation:
More preferably, the relationship should satisfy the following equation:
In a still more preferred embodiment, the zone length of the second zone is also
constrained to be less than or equal to 0.4 times the first zone length.
[0013] In another preferred embodiment, a separate zone is provided primarily for drafting
the already broken filaments without further breaking.
[0014] In further embodiments, a draw zone is also utilized to draw the fiber without breaking
filaments in a draw zone that precedes the break zones and can draw the fiber with
or without the application of heat. Additionally an annealing zone is employed when
desired to heat the fibers and control product features such as shrinkage. An annealing
zone is most often part of the drawing zone, but may be applied at a variety of locations
in the process.
[0015] The process produces novel products by providing the opportunity to introduce a variety
of fibers to the process in a way not previously disclosed to make a wide range of
stretch broken yarns. For instance, with a variety of different zones employed in
the process, additional fiber can be introduced at different locations in the process
to achieve unusual and novel results. Typical of such products are those that blend
continuous filament yarns with the discontinuous filament yarns by introducing the
continuous filament yarns at a location downstream from the break and draft zones
and upstream of the consolidation zone or zones. Other products employ polymeric materials
with properties not envisioned for use in a stretch-breaking process, especially one
with applicant's unique operating procedures. Such products include the following:
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length distribution characterized by the fact that 5%
to less than 15% of the filaments have a length that is greater than 1.5avg.
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length of the filaments is greater than 6 inches,
and wherein the fiber includes continuous filaments intermingled with the discontinuous
filaments along the length of the yarn, the continuous filaments having less than
10% elongation to break.
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length of the filaments is greater than 6 inches,
and wherein the fiber includes continuous filaments intermingled with the discontinuous
filaments along the length of the yarn, the continuous filaments comprise elastic
filaments having an elongation to break greater than about 100% and an elastic recovery
of at least 30% from an extension of 50%.
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length of the filaments is greater than 6 inches,
wherein at least 1% of the discontinuous filaments in the yarn by denier comprises
a fiber having a filament-to-filament coefficient of friction of 0.1 or less. Preferably,
the low friction component is a fluoropolymer.
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length distribution characterized by the fact that 5%
to less than 15% of the filaments have a length that is greater than 1.5avg, and wherein
the filament cross-section has a width and a plurality of thick portions connected
by thin portions within the filament width, and the thin portions at the ends of the
discontinuous filaments are severed so the thick portions are separated for a length
of at least about three filament widths to thereby form split ends on the filaments.
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length distribution characterized by the fact that 5%
to less than 15% of the filaments have a length that is greater than 1.5avg, and the
fiber in the yarn comprises two fibers that have visually distinct differences detectable
by an unaided eye. Preferably, the differences are a difference in color, the colors
of the fibers excluding neutral colors having a lightness greater than 90%, and wherein
the colors of the fibers have a color difference of at least 2.0 CIELAB units, the
lightness and color difference measured according to ASTM committee E12, standard
E-284, to form a multicolored yarn.
- a yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length, avg, of the filaments is greater than 6 inches,
and wherein at least 1% of the discontinuous filaments in the yarn by denier comprises
a fiber having filaments with a latent elasticity of 30% or more. Preferably, the
fiber is a bicomponent yarn comprising a first component of 2GT polyester and a second
component of 3GT polyester.
[0016] Different processes are disclosed for making some of the products just discussed.
Other processes are disclosed for converting a conventional staple spinning machine
into a machine for making feed fiber for a stretch break type machine. The processes
involve managing the operation of the spinning machine, spinning at least 500 fibers
at a spinning position, to simultaneously produce a plurality of products, having
an individual lot size about 20 to 200 lbs, collected into a container, the lot size
being smaller than a lot of the single large denier tow product; and providing at
least one spinning position with a means for collecting tow from the at least one
spinning position into a container making a low denier tow product.
[0017] Various improvements to conventional stretch break processes are disclosed including:
- gathering the loose filament ends in the break zone and adjacent the exit nip rolls
and directing them toward the fiber core so the loose ends in all directions around
the core are constrained to be within a distance from the center of the core of not
greater than the distance of the center of the core from each respective end of the
exit nip rolls for the break zone to minimize wrapping of the loose ends on the exit
nip rolls.
- arranging the paths of the fiber through the functional zones in a stretch break process
to be folded so when a path vector in a first functional zone is placed tail to tail
with a path vector in a next sequential functional zone there is defined an included
angle that is between 45 degrees and 180 degrees resulting in a compact floor space
for the process.
- arranging the path of the discontinuous filament fiber at the exit of the first break
zone and at the entrance and exit of the second break zone to first contact the fiber
to an electrically conductive nip roll before contacting it to an electrically non-conductive
nip roll and to only separate the fiber from an electrically non-conductive nip roll
by first separating the fiber from the electrically non-conductive nip roll before
separating it from an electrically conductive nip roll to thereby minimize static
buildup in the fiber as it passes through the nip rolls.
[0018] Other variations in the process and products produced thereby will be evident to
one skilled in the art of fiber processing from the description that follows.
DESCRIPTION OF THE FIGURES
[0019] Other features of the present invention will become apparent as the following description
proceeds and upon reference to the drawings, in which:
Figure 1 is a schematic elevation view of a process line that includes a first and
a second break zone and a consolidation zone.
Figure 1A is a close up of a roll set where the fiber path is an "omega" path especially
useful with high strength fiber or fiber with a low coefficient of friction.
Figure 2 is a schematic perspective view of filament ends and double gripped filaments
in a fiber being stretch-broken between two sets of rolls.
Figure 3 is a graph of a double gripped fiber ratio versus a total speed ratio for
two cases of stretch breaking fibers using a simulation model.
Figure 4 is a graph of a double gripped fiber ratio versus a speed ratio for a single
case of two break zones for stretch breaking fibers using a simulation model.
Figure 5 is a sensitivity plot of the information of Fig. 4 looking at variations
in the fiber elongation to break, eb.
Figure 6 is a sensitivity plot of the information of Fig. 4 looking at variations
in the length of break zone 2 compared to the length of zone 1.
Figure 7 is a sensitivity plot of the information of Fig. 4 looking at variations
in the total speed ratio for the two break zones.
Figure 8 is a schematic elevation view of a process line that includes a draw zone,
a first and a second break zone, and a consolidation zone where the draw zone may
also function as an annealing zone.
Figure 9 is a schematic elevation view of a process line that includes a draw zone,
a first and a second break zone, a draft zone, and a consolidation zone.
Fig. 10 shows the curves of Fig. 4 with the left vertical axis expanded and a right
vertical axis added to compare the Fig. 4 curves with some actual test data.
Figure 10A is a plot of data from a designed test of operability for different values
of D1 and D2 to collect optimum data for the plot of Fig. 10.
Figure 11 is a schematic elevation view of a machine for practicing the process in
Figures 1, 8, and 9 and variations thereof.
Figure 12 is a perspective view of a swirl jet from Fig. 11 for swirling loose filaments
around the fiber.
Figure 13 is a schematic view of a piddling device for piddling feed fiber through
a fiber distributing rotor and into an oscillating container.
Figure 14 is a section view of the rotor of Figure 13.
Figure 15 illustrates a plot of filament length distribution for an actual yarn test
and from a simulation of that test.
Figures 16 and 17 illustrate a simulation of two comparative examples using only a
single stretch-break zone and the fiber distribution that resulted, which falls outside
of the limits of the invention.
Figures 18 and 19 illustrate simulations of other operating conditions and the fiber
distribution that resulted, which falls within the limits of the invention.
Figure 20 shows the process schematic of Figure 9 where an additional feed fiber is
introduced at the upstream end of the consolidation zone.
Figure 21 shows the process schematic of Figure 9 where an additional feed fiber is
introduced at the upstream end of the first break zone.
Figure 22 shows the process schematic of Figure 9 where a first additional feed fiber
is introduced at the upstream end of the first break zone, and a second additional
feed fiber is introduced at the upstream end of the consolidation zone.
Figure 23 is a schematic elevation view of the process line of Fig. 9 that includes
an annealing zone after the consolidation zone.
Figure 24 shows a photomicrograph of a stretch-broken filament that has split ends.
Figure 25 is a cross section of the filament of Fig. 24.
Figure 26 shows a perspective view of an interlace jet for consolidating the fiber.
Figure 27 shows a cross section 26-26 through the jet of Fig. 26.
Figure 28 shows a pneumatic torsion element for consolidating the fiber, where the
left half of the figure is in section view taken along the fiber path and the right
half is in plan view.
Figure 29 shows an isometric view of a prior art staple spinning machine to provide
large denier tow product feeding a conventional staple yarn process.
Figure 30 shows an isometric view of a staple spinning machine modified to provide
both low denier and high denier tow product.
Figure 31 shows an isometric view of a staple spinning machine modified to provide
low denier tow product from individual positions feeding a stretch break yarn process.
Figure 32 shows a diagrammatic view of a process line having a folded path that saves
floor space.
Figures 33A, B, and C show diagrammatic views of functional zone path vectors for
the zones of Fig. 32.
Figures 34A and 34B shows cross section views of a trough that gathers loose filaments
ends toward the fiber core before the fiber goes through a nip roll.
Figure 35 shows a typical plot of yarn strength versus the distance between two nozzles
of a consolidation device for different average filament lengths.
[0020] While the present invention will be described in connection with a preferred embodiment
thereof, it will be understood that it is not intended to limit the invention to that
embodiment. On the contrary, it is intended to cover all alternatives, modifications,
and equivalents as may be included within the spirit and scope of the invention as
defined by the appended claims.
DETAILED DESCRIPTION
[0021] Referring now to the drawings, Figure 1 shows a schematic of a preferred process
for stretch breaking a fiber 30 to form a yarn 32 using at least a first break zone
34 and a second break zone 36 and a consolidation zone 38. Fiber 30, which may comprise
several fibers 30a, 30b, and 30c is fed into the process at a process upstream end
40 through a first set of rolls 42, comprising rolls 44, 46, and 48. Roll 46 is driven
at a predetermined speed by a conventional motor/gearbox and controller (not shown)
and rolls 44 and 48 are driven by their contact with roll 46. The fiber 30 is fed
to a second set of rolls 50, thereby defining the first break zone 34 between roll
sets 42 and 50. Roll set 50 comprises roll 52, roll 54 and roll 56. Roll 54 is driven
at a predetermined speed by a conventional motor/gearbox and controller (not shown)
and rolls 52 and 56 are driven by their contact with roll 54. The first break zone
34 has a length L1 between the nip of roll 46 and roll 48, which lies on line 58 between
their centers, and the nip of roll 52 and 54, which lies on line 60 between their
centers. The fiber speed is increased within the first break zone 34 by driving the
fiber at a first speed S1 with roll set 42 and driving it at a second speed S2, higher
than speed S1, with roll set 50. The comparison in speeds of the fiber at the two
roll sets, 42 and 50, defines a first speed ratio D1 = S2/S1. There should not be
any slippage between the roll and the fiber, thus, the fiber speed and roll surface
speed at the driven roll 46 are the same, and the fiber speed and roll surface speed
at the driven roll 54 are the same. Increasing the speed of the fiber within first
break zone 34 causes filaments in the fiber longer than the length L1 to be stretched
until the break elongation of the fiber is exceeded and the filaments gripped by both
roll sets will be broken. In the first zone, to break the filaments, the speed ratio
D1 should be such that the maximum imposed strain on the filaments exceeds the break
elongation of the fiber, which is a known requirement for stretch breaking of fiber.
If the fiber fed into the process is a fiber composed entirely of continuous filaments,
and the above conditions for breaking filaments are met, all the filaments will be
broken in the first break zone. After the continuous filaments are broken, the now
discontinuous filament fiber may also be drafted in first break zone 34 to reduce
the denier of the fiber as the speed of the fiber continues increasing until it reaches
the speed S2 of the roll set 50.
[0022] The fiber 30 is fed to a third set of rolls 62, thereby defining the second break
zone 36 between roll sets 50 and 62. Roll set 62 comprises roll 64, roll 66 and roll
68. Roll 66 is driven at a predetermined speed by a conventional motor/gearbox and
controller (not shown) and rolls 64 and 68 are driven by their contact with roll 66.
The second break zone 36 has a length L2 between the nip of roll 54 and roll 56, which
lies on line 70 between their centers, and the nip of roll 64 and 66, which lies on
line 72 between their centers. The fiber speed is increased within the second break
zone 36 by driving the fiber at the second speed S2 with roll set 50 and driving it
at a third speed S3, higher than speed S2, with roll set 62. The comparison in speeds
of the fiber at the two roll sets, 50 and 62, defines a speed ratio D2 = S3/S2. There
should not be any slippage between the roll and the fiber, thus, the fiber speed and
roll surface speed at the driven roll 54 are the same, and the fiber speed and roll
surface speed at the driven roll 66 are the same. Increasing the speed of the fiber
within second break zone 36 causes most filaments in the fiber longer than the length
L2 to be stretched until the break elongation of the fiber is exceeded and most filaments
gripped by both roll sets (doubly gripped filaments) will be broken. In the second
zone, to break the filaments, the speed ratio D2 should be such that the maximum imposed
strain on the doubly gripped filaments exceeds the break elongation of the fiber,
which is a known requirement for stretch-breaking of fiber having discontinuous filaments.
The discontinuous filament fiber may also be drafted in the second break zone 36 to
reduce the denier of the fiber as the speed of the fiber continues increasing until
it reaches the speed S3 of the roll set 62.
[0023] The fiber 30 is fed to a fourth set of rolls 74, thereby defining the consolidation
zone 38 between roll sets 62 and 74. Roll set 74 comprises roll 76 and roll 78. Roll
76 is driven at a predetermined speed by a conventional motor/gearbox and controller
(not shown) and roll 78 is driven by its contact with roll 76. The consolidation zone
38 has a length L3 between the nip of roll 66 and roll 68, which lies on line 80 between
their centers, and the nip of roll 76 and 78, which lies on line 82 between their
centers. The consolidation zone includes some means of consolidation, such as an interlace
jet 83 shown between the roll sets 62 and 74. The fiber speed can be decreased slightly
within the consolidation zone 38 by driving the fiber at the third speed S3 with roll
set 62 and driving it at a fourth lower speed S4 with roll set 74. The comparison
in speeds of the fiber at the two roll sets, 62 and 74, defines a speed ratio D3 =
S4/S3. There should not be any slippage between the roll and the fiber, thus, the
fiber speed and roll surface speed at the driven roll 66 are the same, and the fiber
speed and roll surface speed at the driven roll 76 are the same. The interlace jet
interconnects the filaments by entangling them with one another to form a staple yarn
and in doing so it can slightly shorten the length of the fiber as the yarn is formed
which accounts for the decreased speed in this particular consolidation zone. In some
cases it may be desired to increase the fiber speed within the consolidation zone
38 by driving the fiber at the third speed S3 with roll set 62 and driving it at a
fourth speed S4, higher than speed S3, with roll set 74. In this case some drafting
would occur in the consolidation zone 38 as the speed of the fiber continues increasing
until it reaches the speed S4 of the roll set 74.
[0024] With continuing reference to Figure 1, the roll sets 42, 50, and 62 have been shown
as three roll sets with the fiber passing substantially "straight" through the roll
sets there being a slight wrapping around the rolls. This frequently is a simple effective
way to provide good gripping of the fiber and have a simple fiber thread up path for
the process. It is believed to be important to control static charge build up on the
fibers as they are broken in the break zones 34 and 36. Free fiber ends created by
filament breaking tend to extend from the surface of the fiber repelled by static
forces as the filaments slide one on the other. These extending statically charged
free ends tend to wrap on the nip rolls, especially in roll sets 50 and 62, thereby
creating machine stoppages. It is believed to be beneficial to contact the fiber with
an electrically conductive roll surface to dissipate the static charge. This can be
done by making at least one of the rolls of the nip rolls, gripping the unconsolidated
discontinuous fiber, a metallic conductive surface, for instance, rolls 44, 48, 52,
56, 64, and 68. Roll 76 may also be a conductive surface, but this is not as important
since the free ends are consolidated with the fiber core when passing through this
nip. Likewise, roll 44 may not need to be metallic since the fiber at this point is
still a bundle of continuous filaments and no free ends are present. At roll 48, due
to the dynamic filament breaking taking place in break zone 34, there may be some
free ends present so having roll 48 with a conductive surface may be beneficial. In
the case of roll set 50, rolls 52 and 56 are metallic surfaces contacting a non-conductive,
resilient, elastomer surface on roll 54. It is also important when contacting a roll
set, such as 50, to arrange the path of the discontinuous filament fiber at the entrance
and exit of the roll set to first contact the fiber to an electrically conductive
nip roll before contacting it to an electrically non-conductive nip roll and to only
separate the fiber from an electrically non-conductive nip roll by first separating
the fiber from the electrically non-conductive nip roll before separating it from
an electrically conductive nip roll to thereby minimize static buildup in the fiber
as it passes through the nip rolls. In other words, the first surface contacted by
the fiber entering a nip set should be a conductive surface and the last surface contacted
by the fiber exiting a nip set should be a conductive surface. If instead the fiber
was peeled away from the elastomeric surface of roll 54 after leaving metal roll 56,
a static charge would be generated as the fiber and elastomer were separated and it
would not be readily dissipated since the fiber itself is electrically non-conductive.
Accordingly, the rolls 52 and 56 are angularly located around the center of roll 54
so a wrap angle 51 of about 5 degrees or more occurs on roll 52 before the fiber makes
contact with roll 54, and a wrap angle 53 of about 5 degrees or more occurs on roll
56 after the fiber breaks contact with roll 54. This situation is repeated for roll
set 62.
[0025] Since many of the roll wraps seem to occur as the fiber is exiting a nip between
rolls, it is believed to also be important to keep the fiber in contact with a rigid
nip roll, such as a metallic nip roll, as the fiber leaves a resilient elastomeric
nip roll regardless of whether the rigid or resilient surfaced rolls are conductive
or non-conductive. In this way, if the fiber tends to get embedded in the resilient
surface of the elastomeric roll, it can be "peeled" away from the resilient surface
by following the rigid surface of the opposing nip roll as the fiber takes a small
wrap on the rigid roll. The wrap angles around the metal surfaced rolls discussed
above would accomplish this purpose. This is believed to minimize roll wraps. If the
rigid roll surface is electrically conductive, this is a further advantage as mentioned
above.
[0026] Figure 1A shows another way of threading up the roll sets called an "omega" wrap,
referring to roll set 42. In this alternative, the fiber is fed in under roll 44,
rather than over the top, and is then wrapped around roll 44, roll 46, and under roll
48. This increases the surface contact substantially between the fiber and the rolls
44, 46, and 48. This is a useful technique if the fiber demands good frictional engagement
with the roll set to avoid fiber slippage over the roll set. Conditions when this
is required may be when the fiber is a high strength fiber and a large breaking force
is required to be developed by the roll sets, or when the fiber has a very low coefficient
of friction between filaments in the fiber and between the fiber and the roll surface.
Fluoropolymer fiber, having a coefficient of static friction between filaments of
less than or equal to about 0.1, would be such a fiber that would benefit from an
"omega" wrap when processing it by stretch breaking. With this omega wrap, the roll
48 has a conductive surface and has a large wrap angle 55 of greater than 90 degrees
with the fiber after it has broken contact with roll 46 that has a non-conductive
elastomer surface. This will effectively dissipate the static generated as the fiber
separates from the elastomer surface as discussed above.
[0027] Throughout the industry there are a variety of meanings attributed to the term fiber.
For purposes of this specification the term fiber means an elongated textile material
comprising one or multiple ends or bundles of the same or different material comprising
multiple filaments that can be discontinuous or continuous and are unconsolidated,
thereby retaining significant mobility between the filaments. Filaments are single
units of continuous or discontinuous (i.e. finite length) material. The term yarn
or staple yarn means an elongated textile material that comprises a consolidated fiber
including discontinuous filaments, where the consolidated fiber has a substantial
tensile strength and unity along the length of the yarn and filament mobility is present,
but limited. Continuous filaments may also be present in the yarn or staple yarn.
[0028] The feed fiber for the above described process may come from a wound package of fiber
or may come from a container of piddled fiber from which the fiber may be freely withdrawn
as will be discussed below. The consolidated yarn may be wound into a package or piddled
into a container for transfer to another process or for shipping; or passed on to
other machine elements for further processing.
[0029] A break zone and breaking the filaments refers to increasing the speed of fiber comprising
continuous or discontinuous filaments in a zone for the primary purpose of breaking
fibers in a way that more than 20% and preferably more than 40% of the filaments are
broken. When continuous filaments or discontinuous filaments longer than the break
zone are fed into the break zone 100% of the filaments are broken. A break zone and
breaking the filaments may also include cutting or weakening all or a portion of the
continuous or long discontinuous filaments such as with a cut-converter device or
breaker bar device (as described in U.S. 2,721,440 to New or U.S. 4,547,933 to Lauterbach)
which reduces the breaking forces imposed at the nip rolls and controls some of the
randomness of the breaking position of the filaments in the fiber.
[0030] The first break zone and second break zone means two distinct break zones with the
second one occurring after the first one in the progression of the fiber through the
two break zones. It is intended that the second break zone does not have to be right
next to the first break zone and the first break zone does not have to be the first
zone in a process. The feed fiber entering the first break zone can be continuous
filament fiber, a discontinuous fiber of long length filaments that are to be broken
in the first break zone, or a combination of continuous and discontinuous filament
fiber. It is intended that consolidating includes interconnecting the filaments in
the fiber by any means of consolidating, such a single fluid jet, multiple fluid jets,
a true twisting device, an alternate ply twisting device, an adhesive applicator or
the like, a wrapping device, etc.
[0031] To achieve a practical breaking of fiber in a single break zone, it is known that
the tension to break a fiber decreases as the speed ratio to break the fibers increases.
At a very low speed ratio of less than two, the tension increases rapidly and as it
does it is believed that the tension consolidates the fiber so that the friction between
adjacent filaments increases and individual filament breaking becomes more difficult.
As a result, the tension becomes high and very erratic which leads to operability
problems and breakage of the entire fiber rather than random individual filament breaking.
For this reason, it is desired to operate each break zone at a speed ratio of 2.0
or greater. This is also advantageous for product throughput efficiencies. It is also
desired to provide a large number of filament ends in the consolidated yarn. This
can be done by making the zone length of the second break zone considerably shorter
than the first break zone to shorten the filaments in the fiber and create more filament
ends per inch of consolidated yarn. It is preferred to make the second break zone
length, L2, less than or equal to 0.6 times the first zone length, L1. In a more preferred
embodiment, it is desired to make the second length L2 less than or equal to 0.4 times
the first length L1. There is a practical limit to the minimum length of the second
draw zone where it will be breaking nearly all of the fiber filaments coming from
the first zone. This is undesirable since it increases the tension to a high level
and it is known that the breaking forces increase as the length of the zone decreases.
A practical lower limit for L2 for break zone 2 is L2 ≥ 0.2 L1. The corollary to this
logic is that it is desireable to make the first zone considerably longer than the
second break zone because it is known that the tension to break filaments decreases
in long zones. It is believed important for L1 to be long for any given average filament
length produced (e.g. established by the second break zone) to decrease the breaking
forces required and to present a longer filament length to breaking forces which exposes
more filament weak points for breaking. It is believed desireable to have an average
filament length greater than 6.0 inches, which means from two-break-zone experience
that L2 is roughly greater than about two times the average filament length or 12.0
inches, which means L1 is greater than 1.67x12.0 or 20.0 inches at the maximum desired
L2/L1 ratio of 0.6.
[0032] There is a relationship between the first and second break zones that insures that
the process has good operability and the yarn has certain desirable characteristics
of filament length and distribution and to provide an increased frequency of filament
ends in a stretch-broken yarn. Good operability also provides for the possibility
of robust high speed operation at output speeds greater than 200-250 yards/minute,
and especially greater than about 500 yards/minute. A definition of double gripped
filaments will first be discussed in reference to Figure 2, to better understand the
relationship between the first and second break zones. Figure 2 shows a fiber 30 comprising
only continuous filaments, traveling in a direction 81 and passing through a break
zone 34a, such as the first break zone 34 in Fig. 1. The break zone 34a extends over
a length L1a between two sets of rolls 42a and 50a. The roll set 42a is driven at
a first speed S1a and the roll set 50a is driven at a second speed S2a that is higher
than speed S1a to define a speed ratio D1a = S2a/S1a. The speed of fiber 30 is increased
in the break zone 34a so that all the continuous filaments being fed in at an upstream
end 85 are to be broken in length L1a. Although shown at a position just after roll
set 42a, upstream end 85 refers to a position either just before, just after, or in
the nip of roll set 42a. Throughout this discussion, upstream refers to the direction
the fibers are coming from and downstream refers to the direction the fibers are going
toward. The fiber has an elongation to break that is expressed in a percent and represents
the percent elongation of a filament of the fiber in the direction of an applied load
just before the filament breaks. Typical elongation to break values for spun manmade
fibers before strengthening by drawing can be about 300% for polyester, and after
strengthening by drawing can be about 10% for polyester. At any instant in time, such
as the time depicted in Fig. 2, there are some filaments that are broken, such as
filaments 84, 86 and 88, and some filaments that are being stretched and are not yet
broken, such as filaments 90 and 92. Filament 84 is referred to as a floating uncontrolled
filament since it has neither upstream end 84a or downstream end 84b gripped and controlled
by either roll set 42a or 50a. Filament 86 is referred to as a single gripped uncontrolled
filament with a downstream uncontrolled end since it is gripped and controlled only
by one roll set 42a and a downstream end 86a is uncontrolled by either roll set 42a
or 50a. If the end 86a protrudes some distance d from the central region of the fiber
30 as shown, it may present a problem at roll set 42a or 50a by wrapping around one
of the rolls rather than proceeding through the process in direction 81. Filament
88 is referred to as a single gripped controlled filament which is gripped and controlled
by one roll set 50a and has upstream end 88a which is not gripped by either roll set
42a or 50a. End 88a is less of a problem than end 86a in that it is being pulled through
the process rather than being pushed as is end 86a. End 88a is less likely to separate
from the central region of the fiber as does end 86a. Filaments 90 and 92 are referred
to as double gripped support filaments since they are gripped and controlled by both
roll sets 42a and 50a at the instant of time shown. They act as a "scaffold" to hold
the other uncontrolled filaments in place in the central region of the fiber. They
are under significant tension, unlike the other filaments that are only singly gripped,
and so they tend to hold the other filaments tightly in the central region and limit
the protrusions of ends like end 86a. At a next instant in time, filaments 90 and
92 will be broken, but at that next instance in time other filaments, such as filament
86 whose end 86a will become gripped by roll set 50a, will become double gripped.
It is believed to be important to provide at least a minimum number of double gripped
filaments present at any instant in time to maintain a scaffold of filaments to assure
good runnability of the process. The total number of filaments at the upstream end
85 is equal to the number of double gripped filaments plus the number of uncontrolled
filaments, both floating and single gripped.
[0033] A modeling process is used to predict the number of double gripped filaments under
a variety of process conditions. The analytical expression works for a single zone
with continuous feed filaments. The simulation imposes the same first principles for
a multi-zone process where the feed into each zone can be continuous or discontinuous.
Single zone results agree well with each other. An analytic expression for a support
index in a single break zone was derived from first principles using the following
assumptions:
- Feed fiber is continuous
- Mass is conserved in the zone
- Fiber speed is specified at the upstream and downstream boundaries of the zone
- Filaments break independently
- Filaments break uniformly along the zone length
The derived expression for a "support index" is:
where
- SI =
- Number of support fibers / Number of uncontrolled fibers
- Ln =
- natural logarithm
- D =
- draft = velocity ratio in the zone
- eb =
- elongation to break of fiber; 10% is expressed as 0.1
[0034] A Monte Carlo computer simulation was developed to analyze a coupled process with
multi-zone breaking and drafting. The simulation tracks fiber motion through the process,
with fiber speed in each zone imposed (as an example) by gripping roll-sets. The imposed
kinematics dictates the motion of single gripped and double gripped filaments. Randomness
occurs during the breaking of double gripped filaments. Following the treatment of
Ismail Dogu, "The Mechanics of Stretch Breaking", (Textile Research Journal, Vol.
42, No. 7, July 1972), the filament builds up strain until the break elongation is
reached, at which time it breaks randomly along the zone length. Filament breaks are
independent from others in the fiber. Floating filaments are treated in a number of
ways, from "ideal drafting" --- filaments take on the upstream roll-set speed until
the leading end reaches the downstream roll-set --- to options where its speed depends
on the speed of neighboring filaments. Simulation results agree well with single zone
analytical predictions for the support index and process tension, and with measured
process tension. The simulation model is run in Matlab® 5.2 from Mathworks, Inc. of
Natick, MA 01760. Results can be obtained with a reasonable effort for 1000 filaments
on a computer with an Intel Pentium II, 450 MHz processor. It is also practical to
handle up to 3000 filaments with this system. Simulation of fiber length distribution
for a two-zone breaking process agrees well with the measured distribution.
[0035] With continuing reference to Figure 2, when looking at the number of double gripped
filaments it is useful to discuss the number as a percent comparing the number of
double gripped filaments to the number of uncontrolled filaments at the upstream end
of a zone length, such as upstream end 85 of length L1a. The number of double gripped
filaments is, by definition, the same at the upstream end 85 and downstream end 93
of zone length L1a. The number of uncontrolled filaments is always more at the upstream
end than the downstream end of zone length L1a. At the downstream end of L1a, the
fiber of discontinuous filaments has been drafted due to the speed ratio, D1a, so
the denier of the fiber is always less at the downstream end. There are always more
uncontrolled filaments that need to be supported at the upstream end for the same
number of double gripped support filaments.
[0036] Reference is now made to Figure 3, which shows the results of a modeling simulation
of one case where one break zone is employed to accomplish a total speed ratio and
another case where two break zones are employed to accomplish the same total speed
ratio. It is known, that the total speed ratio for multiple zones can be calculated
by multiplying together the individual speed ratios for individual zones (Dt = D 1
x D2) or by calculating the overall speed ratio (Dt = S3/S 1). On the vertical scale
of Figure 3 is shown the ratio of the number of double gripped support filaments,
N
dg, to the total number of uncontrolled filaments, N
uc, counted at the upstream end of the single zone, and at the upstream end of the second
break zone for the two break zones (i.e. for the assumptions made for the two zones
this will be the lowest value of N
dg/N
uc). Other assumptions for the two zones are:
- L2=0.33 L1
- D1=D2
- D1 ≥ 2.0; D2 ≥ 2.0
- elongation to break of the fiber in both break zones, eb = 0.121
The curves in the figure relate the total speed ratio to the ratio of double gripped
filaments and uncontrolled filaments, N
dg/N
uc. The single zone case is shown in a dashed line 94 with diamond data points and the
two zone case is shown in a solid line 96 with square data points. As can be seen
for all conditions of the same total speed ratio, the two zone case always provides
a higher ratio of double gripped filaments to uncontrolled filaments, which it is
believed, will provide better process operability.
[0037] Looking at the single break zone in Fig. 3, one can see that as the speed ratio increases,
the number of double gripped filaments decreases and as the speed ratio decreases,
the number of double gripped filaments increases. Applying this observation to the
two zones, one can see a problem for achieving a given total speed ratio. If one wants
to increase the number of double gripped filaments in the first zone by decreasing
the speed ratio in the first zone, the speed ratio must necessarily increase in the
second zone to maintain the same total speed ratio. This will then decrease the number
of double gripped filaments in the second zone, which is undesirable. This problematic
relationship is illustrated in Figure 4.
[0038] Figure 4 shows N
dg/N
uc along the vertical axis as in Fig. 3, however, along the horizontal axis is a relationship
between the speed ratios of the two break zones. Since a speed ratio of 1 for a zone
means the speed "in" equals the speed "out" and no breaking of filaments is taking
place, the value of 1 is subtracted from the first break zone speed ratio D1 and the
second break zone speed ratio D2 when comparing the two speed ratios. In this case
when the second speed ratio is equal to 1, the relationship (D2-1)/(D1-1) will equal
zero and the value where the curve intersects the vertical axis will indicate N
dg/N
uc for a single break zone. For instance, for the case of Dt = 25 and D2 = 1, the value
at the vertical axis will be about 0.01 which is the same as the value for Dt = 25
looking at the single zone in Fig. 3. The assumptions for the curves in Fig. 4 for
the two zones are:
Since the second zone speed ratio is in the numerator, the curve 100 for the second
zone has the shape of the curves in Fig. 3. Since the first zone speed ratio is in
the denominator, the curve 98 for the first zone has a shape that is the inverse of
the curves in Fig. 3. Moving along the horizontal axis, one can see that the lowest
value encountered in one of the two zones for N
dg/N
uc (that will determine an operability limit) is represented by the heavy solid line
102 that includes a portion 104 of the first break zone curve 98 for the values of
N
dg/N
uc less than about 0.7 and includes a portion 106 of the second break zone curve 100
for the values of N
dg/N
uc greater than about 0.7. If a level of 0.02, or 2%, is set as a desirable minimum
for N
dg/N
uc as represented by line 108, this would indicate that a value of (D2-1)/(D1-1) of
between about 0.2 (where dashed line 110 intersects the horizontal axis) and 2.0 (where
dashed line 112 intersects the horizontal axis) should be maintained at the conditions
indicated for this plot. The optimum condition would be about 0.7 (where dashed line
114 intersects the horizontal axis) where both zones would have a value of N
dg/N
uc of about 0.04 or 4%. The value of N
dg/N
uc drops rapidly below the optimum value of 0.7 for (D2-1)/(D1-1), and drops much less
rapidly above 0.7. Also the value for N
dg/N
uc essentially levels out above a value of about 5.0 for (D2-1)/(D1-1). An upper limit
for (D2-1)/(D1-1) is therefore less critical than a lower limit to assure good operability
of the stretch-break process using two break zones.
[0039] The modeling simulation process was applied to additional two zone cases and was
used to explore the sensitivity of the optimum values for (D2-1)/(D1-1) to maximize
the number of double gripped fibers to give an acceptable value of N
dg/N
uc for good operability. Figure 5 shows the sensitivity to the fiber elongation to break
parameter. Three different curves are plotted similar to the curves in Fig. 4 where
each curve represents a different value for the fiber elongation to break, e
b. The curves representing the value of e
b = 0.1 are exactly the same as for the curves in Fig. 4. Assumptions for the three
curves are:
It can be seen that the number of double gripped fibers increases with an increase
in e
b from 0.05 to 0.15, but the value for the optimum of (D2-1)/(D1-1) stays about the
same at about 0.7, where dashed line 116 passes through the intersection of each pair
of zone curves and the horizontal axis. If one wished to improve operability of a
given two break zone process, one could keep all process parameters except e
b the same, and add some fibers that have a higher elongation to break to improve the
operability. However, this may change the yarn product properties.
[0040] Figure 6 shows the sensitivity to the ratio of zone lengths parameter. Three different
curves are plotted similar to the curves in Fig. 4 where each curve represents a different
value for the ratio of the break zone length L2 to L1. The value of L2 = 0.33 L1 is
the same as for the curves in Fig. 4. Assumptions for the three curves are:
For zone 1, all three curves are the same and fall on top of one another. It can
be seen that the number of double gripped fibers (N
dg/N
uc ratio) increases only slightly as L2 decreases from 0.5L1 to 0.25 L1, and at the
same time the value for the optimum of (D2-1)/(D1-1) changes only slightly from about
0.5 to about 0.8. This change in (D2-1)/(D1-1) can be seen between where dashed line
118 passes through the intersection of each pair of zone curves for L2 = 0.5 L1 and
the horizontal axis, and where dashed line 120 passes through the intersection of
each pair of zone curves for L2 = 0.25 L1 and the horizontal axis. It seems that in
a two break zone process, varying the ratio between L2 and L1 by reducing L2 from
0.5 L1 to 0.25 L1 can improve operability of the process slightly.
[0041] Figure 7 shows the sensitivity to the total speed ratio parameter. Three different
curves are plotted similar to the curves in Fig. 4 where each curve represents a different
value for the total speed ratio, Dt. The curves representing the value of Dt = 25
are exactly the same as for the curves in Fig. 4. Assumptions for the three curves
are:
It can be seen that the number of double gripped fibers increases with a decrease
in Dt from 50 to 4, but the value for the optimum of (D2-1)/(D1-1) stays about the
same at about 0.7, where dashed line 122 passes through the intersection of each pair
of zone curves and the horizontal axis. If one wished to improve operability of a
given two break zone process, one could keep all process parameters except Dt the
same, and decrease Dt to improve the operability. Since process productivity is highly
dependent on Dt, however, this change to improve operability may make the process
uneconomical.
[0042] Figure 8 is a schematic elevation view of another embodiment of the stretch-break
process line that includes the addition of a draw zone 124 to the embodiment of Fig.
1 which has a first break zone 34, a second break zone 36, and a consolidation zone
38. The draw zone may also function as an annealing zone. Fiber 30, which may comprise
several fibers 30a, 30b, and 30c as in Fig. 1, is now fed into the process at a process
upstream end 126 through a zeroth set of rolls 128, comprising rolls 130, 132, and
134. Roll 132 is driven at a predetermined speed by a conventional motor/gearbox and
controller (not shown) and rolls 130 and 134 are driven by their contact with roll
132. The fiber 30 is then fed to the first set of rolls 42, thereby defining the draw
zone 124 between roll sets 128 and 42. The draw zone 124 has a length L4 between the
nip of roll 132 and roll 134, which lies on line 136 between their centers, and the
nip of roll 44 and 46, which lies on line 138 between their centers. The fiber speed
is increased within the draw zone 124 by driving the fiber at a feed speed, Sf, with
roll set 128 and driving it at the first speed, S1, higher than speed Sf, with roll
set 42. The comparison in speeds of the fiber at the two roll sets, 128 and 42, defines
a draw speed ratio D4 = S1/Sf. There should not be any slippage between the roll and
the fiber, thus, the fiber speed and roll surface speed at the driven roll 132 are
the same, and the fiber speed and roll surface speed at the driven roll 46 are the
same.
[0043] Within the draw zone 124 there can be a fiber heater 140 that may take many forms;
the form shown here is a curved surface 142 that contacts the fiber over a length
that can easily be varied by changing the length of the arc the fiber follows over
the surface 142. For longer heating times at a given fiber speed at the upstream end
126 and a given draw speed ratio D4, the arc and contact length would be longer. Drawing
of the fiber may occur as soon as the fiber is exposed to the tension in the draw
zone 124, so for some polymers, the drawing or elongation of the fiber may occur just
as the fiber is leaving the nip of the upstream rolls, such as rolls 132 and 134.
For some polymers, the draw occurs over a very short length, such as less than 1.0
inch. In this case, the heater serves to anneal the drawn fiber rather than heat it
for drawing. For this type of fiber, if draw heating is required, the rolls 132 and
134 may be heated. Other polymers may not draw until they experience some heat by
contact with the surface of the heater 140. The length of the draw zone is not critical,
and is primarily sized to accommodate the heating device 140. In some cases of operating
the draw zone, the fiber would be drawn without heating (the heater would be turned
off and retracted from contact with the fiber) and in other cases, the fiber would
be heated during the drawing process as shown. In some cases, the fiber may have a
draw speed ratio D4 equal to about one and the fiber may only be heated without stretching.
In this case, the draw zone would function as an annealing zone.
[0044] A draw zone and drawing the fiber refers to stretching continuous filament fiber
in a way that essentially none of the filaments are broken; the filaments remain continuous.
Heating the fiber may or may not be included in drawing. An annealing zone and annealing
the fibers refers to heating a continuous or discontinuous filament fiber while constraining
the length of fiber without significant stretching, and may include some small overfeed
of the fiber into the annealing zone where D4 is a number slightly less than 1.0.
[0045] Using the process of Fig. 8, a new product can be made comprising feeding at least
two different fibers into the process and combining them before breaking in the break
zone, the fiber differences being differences in denier per filament and one of the
fibers having a denier per filament of less than 0.9 and the other fiber having a
denier per filament greater than 1.5. The two fibers would go through the break and
consolidation zones together. The two different fibers can be combined as a feed yarn
either by spinning a single fiber bundle with two different dpf or by bringing together
two different fibers each with a different dpf. In the draw zone, the elongation to
break of the fibers should be similar. If this is a problem, one of the fibers could
be partially pre-drawn to be compatible with the other, or both fibers could be totally
pre-drawn and the fibers fed through the draw zone without drawing. The advantage
of such a new product is that the structural stiffness of the yarn can be determined
by the larger dpf fiber while the softness can be controlled by the smaller dpf fiber.
This overcomes some problems with small dpf yarns that have a good hand but are too
limp when made into fabric.
[0046] Figure 9 is a schematic elevation view of another embodiment of the stretch-break
process line that includes the addition of a draft zone 144 to the embodiment of Fig.
8 which has a draw zone 124, a first break zone 34, a second break zone 36, and a
consolidation zone 38. The draft zone 144 is added between the second break zone 36
and the consolidation zone 38. The fiber 30, exiting the second break zone 36 as in
Fig. 8, is now fed into the draft zone after roll set 62. The fiber 30 is then fed
to a fifth set of rolls 148, comprising rolls 150, and 152, thereby defining the draft
zone 144 between roll sets 62 and 148. Roll 152 is driven at a predetermined speed
by a conventional motor/gearbox and controller (not shown) and roll 150 is driven
by its contact with roll 152. The draft zone 144 has a length L5 between the nip of
roll 62 and roll 68, which lies on line 80 between their centers, and the nip of roll
150 and 152. The fiber speed is increased within the draft zone 144 by driving the
fiber at a speed S3 with roll set 62 and driving it at the fifth speed S5, higher
than speed S3, with roll set 148. The comparison in speeds of the fiber at the two
roll sets, 62 and 148, defines a draft speed ratio D5 = SS/S3. Since there should
not be any slippage between the roll and the fiber, the fiber speed and roll surface
speed at the driven roll 66 are the same, and the fiber speed and roll surface speed
at the driven roll 152 are the same. The length L5 should be about the same length
as the adjacent upstream break zone, in this case, the second break zone length L2
in the configuration shown. This condition means that very few fibers are broken in
the draft zone and instead the discontinuous filaments of the fiber coming from the
second break zone will just be slipped past one another to reduce the denier of the
fiber by an amount proportional to the draft ratio employed, D5. In some cases, a
controlled amount of filaments may be broken to make a more uniform yarn in the same
manner as is described for uniformly drafting short staple filaments of a fiber in
a PCT application WO 98/48088 to Scheerer et.al. Such a system is also illustrated
in catalog CAT. NO. 22P432 97-1-4(NS) published by Murata Machinery, Ltd. entitled
"Muratec No. 802HR MJS, Murata Jet Spinner".
[0047] A draft zone and drafting the fiber refers to increasing the fiber speed in a zone
for the primary purpose of reducing the denier of discontinuous filament fiber in
a way that more than 80% of the fibers remain their same length, that is, 20% or less
of the fibers are broken. It is intended that the draft zone can be at various locations
as long as it is upstream from the consolidation zone, for instance, it may be between
the first break zone and second break zone.
[0048] A process approximating that illustrated in Fig. 8 was operated and data was collected
to determine the limits of good operability, which are plotted in Figure 10. Fig.
10 shows the curves of Fig. 4, with the left vertical axis expanded and a right vertical
axis added to permit plotting of some actual process cases that were run to find the
limits of good operability. Good operability was indicated when the process could
be started up and run making acceptable stretch broken fiber for at least 5 minutes
at an input speed of 1 yard per minute (the output speed from the second break zone
was limited by machine considerations to about 150 ypm). Poor operability was indicated
when filaments of the fiber wrapped around any of the rolls in the process. The consolidation
step was omitted to simplify the process since that step usually does not contribute
significantly to runnabilty problems. The fiber was withdrawn from the process after
roll set 62 (Fig. 8) and was taken up by a waste sucker gun. The tension was indicated
at a position within the first break zone L1 at a position about 6 inches from the
upstream end of L1 using a guide attached to a load cell lightly contacting the fiber.
The tension signal was monitored for variability and spikes when low speed ratios
were being run. Tension spikes greater than 2X the nominal tension signal that occurred
at a frequency of more than twice per minute indicated poor operability and pulsating
operation, whether the process broke down within 5 minutes or not. Parameters held
constant for all test runs are:
eb = 2.38 feed fiber
eb = 0.12 to break zone
L2 = 0.33 L1
L1 = 48"; L2 = 16"
L4 = 66.25"
draw speed ratio D4 = 2.43
draw length L4=112
draw temperature = 188° C over a 12" contact surface
feed material was three fibers of 7320 denier continuous filament polyester, each
from a wound package.
D1 and D2 were both varied to obtain the maximum overall speed ratio, Dt, by setting
D1 at one value and varying D2 until the process would not run. The last run point
without an operability breakdown was the point of good operability plotted in Fig.
10 as a function of maximum Dt and (D2-1)/(D1-1). Figure 10A shows the data that was
collected. The circled data points in Fig. 10A are those that were plotted in Fig.
10. Next to each circled data point is the Dt value and, in parentheses, the value
of (D2-1)/(D1-1). All circled points for maximum total speed ratio fall between a
curve for Dt = 20X and Dt = 50X. A curve for the optimum operating point for (D2-1)/(D1-1)
= 0.7 for a variety of total draw ratios in also shown at 155; the maximum total speed
ratio for good operability along this line was found to be 42.8X at point 157. For
different materials and different zone lengths, these data would be different. The
finish used on the fiber is also a consideration for operability. Too much finish
and the independent filament mobility and breaking in the stretch break zones is adversely
affected and complete fiber break down occurs; too little finish and static becomes
a problem and roll wraps are increased. A finish level of less than about 0.1% is
preferred and less than about 0.04% is more preferred. A typical finish having 0.04%
of a finish comprises a mixture of an ethylene oxide condensate of a fatty acid, an
ethoxylated, propoxylated alcohol capped with pelargonic acid, the potassium salt
of a phosphate acid ester, and the amine salt of a phosphate acid ester. Some polymers,
such as aramids and fluoropolymers, do not require any finish. Other finishes that
may be useful for stretch breaking fiber are found in the '778 reference to Adams
and Japanese Patent Publication 58[1983]-44787 to Hirose et al.
[0049] Referring again to Fig. 10, connecting the data points with line 158 allows one to
compare the test data to the simulation curves 98 and 100 taken from Fig. 4. One can
see the actual operability data (experiment) follows the general trend indicated by
the simulation with the optimum operating point (D2-1)/(D1-1) = about 0.7 being the
same as defined by dashed line 114.
[0050] An apparatus that can be used for operating the processes of Figs. 1, 8, and 9 is
shown in Figure 11. The feed fiber 30 is supplied from one or several of a container
160 of piddled fiber or alternatively, feed fiber can be fed from one or several of
a wound package 162. The fiber 30 passes through some breaker guides 164 that can
be used to bring together multiple ends of fiber and allow the fiber to distribute
in a flat ribbon. The fiber then goes over a guide roll 166 and to a roll set 128a
comprising four rolls 168, 170, 172, and 174, and a nip roll 175, for gripping the
yarn securely at the upstream end of a draw zone 124 during threadup of the fiber.
All rolls 168-174 are driven by a conventional electric motor/gearbox and controller
(not shown), and nip roll 175 is driven by contact with roll 168. The downstream end
of the draw zone 124 is defined by another roll set 42a comprising four rolls 176,
178, 180, and 182, and a start up nip roll 184. All rolls 176-182 are driven by a
conventional electric motor/gearbox and controller (not shown). Start up nip roll
184 is driven by contact with roll 182. It is used to get the fiber started through
the process and it is then retracted out of contact with roll 182. Between roll sets
128a and 42a is an electric heater 140 with curved surface 142 that can have a variable
contact length with the yarn as discussed referring to Fig. 8. A source of electrical
power (not shown) is attached to the heater.
[0051] Following roll set 42a is a first break zone 34 with roll set 50a at the downstream
end which is identical to the roll set 50 in Figs. 1 and 8. Within first break zone
34 is an electrostatic neutralizer bar 186 adjacent drawn and stretch-breaking fiber
30; and a swirl jet 188 through which the fiber 30 passes. The electrostatic neutralizer
bar is electrically energized by an electrical power source (not shown) and is the
type sold by Simco, model no. ME 100. Point source static eliminator devices, such
as devices 187 may be used in place of or in addition to the bar 186 to control static,
especially in the vicinity of the roll sets. As the filaments in the fiber break in
break zone 34 and are drafted into a smaller denier fiber, they rub against one another
and create an objectionable electrostatic charge that causes the filament ends to
be repelled from the central region of the fiber. This fiber looseness and protruding
ends presents problems with the fiber breaking apart and loose filaments wrapping
on one of the downstream rolls. As mentioned above, one way to combat this problem
is with the proper use of metallic surfaces on some of the nip rolls. Another method
of combating these problems is gathering the loose filament ends in the break zone
and adjacent the exit nip rolls and directing them toward the fiber core so the loose
ends in the lateral directions around the core are constrained to be within a distance
from the center of the core of not greater than the distance of the center of the
core from each respective end of the exit nip rolls for the break zone to minimize
wrapping of the loose ends on the exit nip rolls. It is important to apply this method
of control in the first break zone where the loose filament lengths may be longer
and unsupported over a longer length. It is also advantageous to apply it to the second
break zone where loose fibers are still present. A swirl jet 188 is one way to accomplish
this method.
[0052] Referring now to Figure 12, the swirl jet 188 introduces a jet of gaseous fluid to
gently swirl loose filaments around the central region of the fiber, or fiber core,
which is a flat ribbon-like structure. The swirl jet is shown in greater detail in
Figure 12. The swirl jet 188 comprises a body 192 having an upstream end 194, a downstream
end 196, and a cylindrical bore 198 extending throughout the length of the body 192.
The fiber 30 passes through the bore 198 on its way to roll set 50a (see Figure 11).
A fluid passage 200 extends through the body and is in fluid communication with the
bore 198 at the upstream end 194 of the body. The fluid passage intersects the bore
in a way that the fluid is introduced approximately tangent to the bore and angled
toward the downstream end 196 of the body. In this way a counterclockwise swirling
fluid flow (referenced at end 196), generally indicated by the spiral flow path 202,
is generated within the bore 198. This fluid flow tends to wrap loose filaments, that
extend from the central region of the fiber 30, around the fiber core to eliminate
long loose ends that may wrap on downstream rolls. The wrapped filaments are loosely
gathered around the fiber core. For convenience, a thread up slot 204 is provided
in the body 192 along the length of the bore 198 to facilitate threading the fiber
30 in the swirl jet bore.
[0053] Another way to accomplish the method of gathering the loose filament ends in the
break zone and adjacent the exit nip rolls and directing them toward the fiber core
is to use a trough as shown in Figures 34A and 34B. A trough 450 has a shaped end
452 which is spaced adjacent a nip roll set, such as roll set 50a (Fig. 11) at the
end of the first break zone 34. The trough has a longitudinal cavity 454 that is sized
to accommodate the fiber 30 in the zone and has a width 456 that gathers the loose
filaments 458 and 460 on the sides of the fiber core 462 and constrains them from
extending out to the ends of the nip rolls in the roll set. The surface of the cavity
facing the fiber is an electrically conductive surface. Nip roll 54a has ends 462
and 464 and nip roll 52a has ends 466 and 468. The center of the fiber core is indicated
at 470 and the trough directs the loose filaments toward the fiber core 462 so the
loose ends, such as ends 458 extending laterally around the core are constrained to
be within a distance from the center of the core of not greater than the distance
472 of the center of the core from end 468 of the exit nip roll 52a and distance 474
from the end 464 of exit nip roll 54a; in this case, the lesser distance 472 is controlling.
Also, the loose ends, such as ends 460 extending laterally around the core are constrained
to be within a distance from the center of the core of not greater than the distance
476 of the center of the core from end 466 of the exit nip roll 52a and distance 478
from the end 462 of exit nip roll 54a; in this case, the lesser distance 476 is controlling.
[0054] The trough 450 may only be adjacent the nip rolls exiting the zone and extend a short
distance therefrom, or it may extend for nearly the entire length of zone 34 to maintain
control of the loose filaments throughout the zone. The trough 450 may optionally
have a cover 480 to fully contain the loose filaments in all directions, however,
it is most important that the trough contain the filaments laterally to keep them
from extending to the ends of the nip rolls where they are susceptible to wrapping
on the nip rolls. If a cover is used, it should have access for an air ionizing device.
[0055] Referring again to Figure 11, following roll set 50a is a second break zone 36 with
roll set 62a at the downstream end, which is identical to the roll set 62 in Figs.
1 and 8. Within second break zone 36 is an electrostatic neutralizer bar 206 adjacent
the drawn and stretch-breaking fiber 30; and a swirl jet 208 through which the fiber
30 passes. This is similar to the configuration of the first break zone just discussed.
Also present in the second break zone adjacent its upstream end and next to roll set
50a is an aspirator jet 212. Aspirator jet 212 provides a gentle flow of gaseous fluid
in the direction of travel of fiber 30 to capture and propel loose filaments ends
coming out of the roll set 50a so they will not wrap on the rolls in roll set 50a.
Aspirator jet 212 is the type available from Airvac model no ITD 110. Such an aspirator
may also be used in the first break zone 34 next to roll set 42a if the fiber entering
the zone has some discontinuous filaments present.
[0056] Following roll set 62a is a draft zone 144 with roll set 148a at the downstream end
which is identical to the roll set 148 in Fig. 9. Within draft zone 144 is an aspirator
jet 214, snubbing bars 216, and guide bars 218. The snubbing bars provide some resistance
to filament drafting to give a more uniform denier to the fiber. It may also be useful
to provide a swirl jet, such as swirl jet 208, upstream and adjacent the roll set
148a.
[0057] Following roll set 148a is a consolidation zone 38 with roll set 74a at the downstream
end which is identical to the roll set 74 in Figs. 1, 8 and 9. Within consolidation
zone 38 is an aspirator jet 220 and an interlace jet 83a. In practice, interlace jet
83a is usually placed in the consolidation zone 38 at a distance from roll set 148a
of about 1/3 to 1/2 of the length of the consolidation zone. Figure 26 shows the interlace
jet 83a in a perspective view and Figure 27 a cross section view with a stretch broken
fiber 30 entering the fiber passage 320. The fiber passage 320 preferably has a rounded
triangle cross-section, seen at the entrance end 322. The jet 83a has a first groove
wall 324 in an entrance guide surface 326 that provides a coanda effect in conjunction
with entrance exterior surface 328 at the entrance end 322; and a second groove wall
329 (Fig. 27) in an exit guide surface 330 of the jet that provides a coanda effect
in conjunction with exit exterior surface 332 at an exit end 334 of the fiber passage
320. A string up slot 336 intersects fiber passage 320. Referring to Figure 27, a
fluid inlet passage 338 provides fluid to the fiber passage 320 to interlace the fiber
to consolidate it into a yarn. The fluid passage 338 is arranged at angle 340 toward
the downstream end of the jet at exit end 334, in the direction of the fiber travel
through the jet, to minimize the exhaust of fluid out of the upstream end of the fiber
passage. In addition, the interlace jet yarn passage 320 is arranged at an angle 342
relative to the fiber path 344 between roll set 148a and 74a (Fig. 11) so that fluid
which does exhaust out the upstream end of the yarn passage is directed downward away
from the fiber path. Guides 346 and 348 may be employed to assist in guiding the fiber
through the jet. This handling of exhaust fluid from the upstream end of the yarn
passage minimizes the spreading of any loose filaments in the fiber as the fiber enters
the interlace jet. Such an interlace jet 83a is described in more detail in U.S. Patent
6,052,878 to Allred et al, which is hereby incorporated herein by reference. Other
filament interconnecting jets would work in this embodiment. One other such jet is
that described in the Murata Jet Spinner catalog and the WO patent publication '088
already referenced above. Another interconnecting jet is described in U.S. 4,825,633
to Artz et al, which is hereby incorporated herein by reference. The fiber 30, after
passing through the consolidation device (such as one of the jets just discussed,
or other means disclosed above), becomes a consolidated yarn 32 (Fig. 11) having good
cohesiveness and strength.
[0058] The Artz jet is discussed further referring to Figure 28 that shows the left half
in section view taken along the fiber path and the right half in plan view. In U.S.
Patent 4,825,633, the jet is referred to as a pneumatic torsion element, which may
be controlled in the manner of U.S. Patent 5,048,281. The pneumatic torsion element
83b comprises an injector component or first nozzle 350, having a spinning bore 351,
and a torsion component or second nozzle 352, having a spinning bore 353. The two
components are held in relation to one another by a common holding device 354 that
also houses a first evacuation chamber 356 and a second evacuation chamber 358 for
cleaning up debris associated with the fiber. The stretch broken fiber 30 first passes
through the bore of first nozzle 350. It is believed that this first nozzle acts to
forward the fiber and apply some twist to loose filaments at the periphery of the
twisting fiber core that is formed by the second nozzle. The fiber then passes through
the bore of second nozzle 352. It is believed that this second nozzle acts to twist
the filaments in the fiber core upstream of the second nozzle and through the first
nozzle without creating interlace between the filaments in the yarn. Such an understanding
is consistent with the operation of the Murata twin-jet arrangement discussed in an
article in the Journal of the Textile Institute, 1987, No. 3 pages 189-219 entitled
" The Insertion of 'Twist' into Yarns by Means of Air Jets" by P. Grosberg, W. Oxenham,
and M. Miao; the article consists of Part I: an Experimental Study of Air-Jet Spinning;
and part II: Twist distribution and Twist-Insertion Rates in air-Jet Twisting. First
evacuation chamber 356 is located adjacent the exit end 360 of first nozzle 350 and
is in fluid communication with a source of vacuum at one side 362 and is in fluid
communication with the atmosphere at an opposite side 364. Air flowing from side 364
to 362 across the path of the fiber removes loose broken filaments and polymer or
finish powder and dust from the fiber path. The fiber then passes through the second
nozzle 352 and through a string-up opening 366 and the second evacuation chamber 358.
Both the string-up opening and second evacuation chamber are near the exit end 368
of the second nozzle 352. The second evacuation chamber 358 includes a string-up slot
370 along its length that may be covered after string-up by a cylindrical cover (not
shown). Such a cover may rotate about the outer surface 372 of the holding device
354 to cover and uncover the slot, when the surface is a cylindrical surface surrounding
the chamber 358 that mates with the cover. The second evacuation chamber is in fluid
communication with a source of vacuum at one side 374 and is in fluid communication
with the atmosphere at string-up slot 370 (when the cover is open or absent) and ends
376 and 378. Air flowing from ends 376 and 378, and through slot 370, pass along the
path of the fiber and remove loose broken filaments and polymer or finish powder and
dust from the fiber path. Operation of the torsion element 83a is not dependent on
the first and second evacuation chambers, but they contribute to reliability of the
element by keeping it clean.
[0059] The first nozzle or injector component 350 has pressurized gas, preferably air, supplied
through a line 380 into a ring channel 382 that directs the fluid to multiple compressed
fluid channels, such as 384 and 386. Channels 384 and 386 intersect the spinning bore
351, having a diameter d
1, in a known fashion at a location tangent to the bore diameter and at an angle 388
slanted toward the direction of fiber travel through the bore. The intake opening
389 of bore 351 of first nozzle 350 may be a straight cylindrical shape as shown or
may be conically tapered and include notches to influence the propagation of twist
in the fiber. The second nozzle or torsion component 352 likewise has air supplied
through a line 390 into a ring channel 392 that directs the fluid to multiple compressed
fluid channels, such as 394 and 396 which intersect bore 353, having a diameter d
D. First nozzle 350 has a characteristic distance l
1 from end 360 to a channel such as 386, and second nozzle 352 has a characteristic
distance l
D from an entrance end 398 to a channel such as 396. The first nozzle 350 is spaced
from the second nozzle 352 by a distance "a" measured between compressed fluid channels
where they intersect the spinning bore of each nozzle. This distance is adjusted for
the particular fiber being processed and may be larger for fibers that have a large
average filament length and smaller for fibers having a small average filament length.
The first and second nozzles 350 and 352 are adjustably held in place in common holding
device 354 by fasteners, such as setscrews (not shown) to facilitate adjustment of
the distance "a". Alternatively, each nozzle may have independent holding devices
and be mounted spaced apart on the machine frame (not shown). For any process for
consolidating discontinuous filament fiber having an average filament length greater
than 4.0 inches, and preferably greater than 6.0 inches, it has been surprisingly
discovered that the strength uniformity of the yarn is maximized when the distance
"a" is set proportional to the average filament length of the fiber.
[0060] Referring to the apparatus of Fig 11, the pneumatic torsion element 83b is placed
in the consolidation zone 38 in place of the device 83a and aspirator 220 is removed.
Referring again to Figure 28, the first nozzle 350 is set as close as possible to
the nip roll set 148a (Fig. 11), being about 1.0 inch from the nip to the first nozzle
location where the fluid channels 384 and 386 intersect spinning bore 351. The second
nozzle is set at various distances "a" away from the first nozzle location measured
to where the fluid channels 394 and 396 intersect spinning bore 353.
[0061] Figure 35 shows a plot of yarn strength for a yarn having an average filament length
"avg", with data points for each average length measured at different spacings "a"
between the fluid channels in the first and second nozzles, 350 and 352, respectively
in Fig. 28. At each distance, "a", several yarn samples are taken and an average strength
number in grams per denier (gpd) is obtained by the Lea Product method. For the curves
labeled 8.0, 8.9 and 17.5, it can be seen in the plot that the strength peaks at a
particular value where the distance between nozzles is yy inches. Comparing this to
the average filament length for the yarn being processed, forms a ratio avg/yy that
is useful for selecting the appropriate value for "a". Repeating this test for several
different yarn lengths resulted in values for "a" ranging from 0.74 avg to 1.53 avg
or preferably 0.5 avg to 2.0 avg, with the mean and preferred value being 1.1 avg.
These results will be discussed further referring to tests 20-23 below. Another test
(not shown) where the second nozzle remained spaced from the nip rolls and the first
nozzle was moved close to the second nozzle resulted in lower strength values for
the consolidated yarn, so the important relationship is believed to be the distance
between the nozzles, rather than just the distance of the second nozzle from the nip
roll.
[0062] Referring to Figure 11, following roll set 74a the consolidated yarn is directed
to a winder 222. Between roll set 74a and the winder 222 is an aspirator jet 224 and
a grooved guide roll 226. The winder comprises a dancer arm and grooved roll 228 attached
to a controller (not shown) for controlling the winder speed; a traverse mechanism
230 for traversing the yarn 32 along the axis of a yarn package 232; and a driven
spindle 234. The winder is of a conventional design that requires no further explanation
to one skilled in winding art.
[0063] Figure 11 shows a process with all the functional zones that in some way treat the
yarn being in essentially a straight line path. Figure 11 shows the functional zones
of the draw zone 124, the first break zone 34, the second break zone 36, the draft
zone 144, and the consolidation zone 38 all in a line from left to right, the fiber
following a substantially straight path through each functional zone, each functional
zone path defining a unit path vector (a vector having a direction, and a magnitude
of unity) having a head in the direction of fiber travel and a tail. The process functions
well, but it takes up a lot of floor space. For production machines in a factory,
optimum use of floor space is important to keep costs down. Figure 32 shows a stretch
breaking apparatus 400 for a process where the path of the fiber through one or more
of the functional zones is arranged to be folded so when a path vector in a first
functional zone is placed tail to tail with a path vector in a next sequential functional
zone there is defined an included angle that is between 45 degrees and 180 degrees
resulting in a compact floor space for the process.
[0064] Referring to Fig. 32, the stretch break apparatus 400 comprises a draw zone 402 between
roll sets 404 and 406, a first break zone 408 between roll sets 406 and 410, a second
break zone 412 between roll sets 410 and 414, and a consolidation zone 416 between
roll sets 414 and 418. The consolidated yarn is wound up on a winder system at 420.
Like the apparatus in Fig. 11, the apparatus 400 also includes a heater 140, an electrostatic
bar 186, swirl jets 188 and 208, a consolidation device 83, such as 83a (Figs. 26
and 27) or 83b (Fig. 28), and various other forwarding jets, guides, nip rolls, etc.
In addition, there is a heat shield 417 between heater 140 and the first break zone
408. For flexibility in making various products, a second fiber feed is present at
419 after the draw zone 402 and before the first break zone 408. A third fiber feed
location is present at 421 after the second break zone 412 and before the consolidation
zone 416. In operation, a feed fiber 30 enters the stretch break apparatus 400 from
a creel, not shown, at position 424 in direction of a path vector 426 having a head
425 and a tail 427. Path vector 426 is not a path vector for a functional zone, since
the fiber is just being transported at this point and is not being treated in any
way. The fiber 30 passes through roll set 404 and travels along a path vector 428
through the functional zone for drawing the fiber, draw zone 402. The fiber 30 then
passes through roll set 406 and travels along a path vector 430 through the functional
zone for breaking, first break zone 408. The fiber then passes through roll set 410
and travels along a path vector 432 through the functional zone for breaking, second
break zone 412. The fiber then passes through roll set 414 and travels along a path
vector 434 through the functional zone for consolidating, consolidation zone 416.
The consolidated yarn 32 is then wound into a package at winder 420.
[0065] Figures 33A, B, and C shows the arrangement of vectors to define the folding that
takes place between the paths for the functional zones. In Fig. 33A, sequential functional
zone path vectors 428 and 430 are placed together tail to tail. Path vector 430 is
placed with its tail coinciding with the tail of path vector 428 and the included
angle between the two straight line vectors is indicated at 436 and is about 180 degrees.
In Fig. 33B, sequential functional zone path vectors 430 and 432 are placed together
tail to tail. Path vector 432 is placed with its tail coinciding with the tail of
path vector 430 and the included angle between the two straight line vectors is indicated
at 438 and is about 90 degrees. In Fig. 33C, sequential functional zone path vectors
432 and 434 are placed together tail to tail. Path vector 434 is placed with its tail
coinciding with the tail of path vector 432 and the included angle between the two
straight line vectors is indicated at 440 and is slightly more than 90 degrees. Also,
if there were only two functional zones present in the stretch break apparatus, a
break zone and a consolidation zone, the path vector 430 of the fiber in the first
break zone 408 extends in one direction and the path vector 434 of the fiber in the
consolidation zone 416 is folded to extend in a direction substantially 180 degrees
opposite to the path in the break zone. This makes for a compact arrangement taking
up a minimum of floor space. It is not necessary that all sequential functional zones
be folded, but to save space, at least two sequential zones should have the fiber
path folded going from one zone to the next.
[0066] This folding of the paths of the fiber through the functional zones, so that when
a path vector in a first functional zone is placed tail to tail with a path vector
in a next sequential functional zone there is defined an included angle that is between
45 degrees and 180 degrees, results in a compact floor space for the apparatus to
practice the stretch breaking process. In a case where there are more than two functional
zones, there may be a plurality of included angles, each between sequential functional
zones where the fiber path is folded. In the case where there are a plurality of folds
and included angles, the folded path system of the invention is alternatively defined
when the sum of the absolute value of all the individual included angles between sequential
functional zones is preferably 90 degrees or more and is most preferably 180 degrees
or more. The arrangement shown in Fig 32 is only one folding arrangement for a stretch
breaking process and the concept of folded paths is applicable to other stretch breaking
processes and other arrangement of path vectors.
[0067] The yarn produced by the apparatus of Fig. 11 is a discontinuous filament staple
yarn with a denier that can be readily used in textile end applications without further
preparation other than conventional dyeing or the like. The linear density of the
staple yarn product is typically about equal to or less than 1000 denier, or alternatively,
is a staple yarn having 500 or less filaments per cross-section where the linear density
may be more than 1000 denier. It is believed significant that the process can economically
operate with a relatively small denier piddled fiber, which eliminates a costly winding
step and permits use of undrawn fibers that are sometimes difficult to wind in a package
successfully. This is in contrast to a sliver stretch-breaking device such as that
in the '556 reference discussed above. The process of the invention using piddled
feed fiber 30 for a stretch-break operation to produce a consolidated yarn 32 is believed
to be particularly advantageous. Such a process comprises: withdrawing a fiber at
a speed greater than 1.0 meter per minute from a container holding continuous filament
fiber that has been piddled therein, the fiber having a denier of between 2,000 -
40,000 and the container holding between 10-200 pounds of fiber, and feeding the fiber
to a fiber break zone, and breaking the fiber in the break zone by increasing the
fiber speed within a predetermined zone length at a speed ratio greater than 2.0,
and consolidating the fiber downstream from the break zone to form a staple yarn.
Preferably, before breaking the fiber it is drawn and annealed in a draw zone upstream
of the break zone by increasing the fiber speed within a predetermined draw zone length
and heating the fiber within the length.
[0068] The piddled fiber is preferably obtained most economically by a modified method of
operating a staple fiber spinning machine having a single polymer supply system feeding
multiple spinning positions normally combined together to make a single large denier
tow product collected into a container to be later converted to staple fiber. Figure
29 illustrates such a system having a staple fiber spinning machine 500 with, for
instance, 10 positions, such as individual positions 502, 504, 506, 508 and 510, the
machine provided with polymer from a single supply at 511. The positions are all combined
into a large denier tow product 512, which is piddled into a large container 514.
In a conventional staple converting process, the container 514, holding over 1000
lbs of product is combined with other containers and goes through a conversion process,
generally designated at 516 that ultimately results in staple fiber being spun into
yarn in a carding, combing, spinning system 518.
[0069] Referring now to Figure 30, he improvement comprises managing the operation of the
modified staple spinning machine 501, having at least about 10 spinning positions,
to simultaneously produce a plurality of low denier tow products rather than a single
large denier tow product, the low denier products each being less than about 20% of
the large denier tow product. In Figure 30, it is envisioned that at least 2 positions,
and preferably at least 5 positions, for instance positions 502, 504, 506, 508 and
510 would produce individual low denier tow products and the remaining 5 or more could
continue to produce a large denier tow product, or, referring to Figure 31, all positions
on the modified staple spinning machine 503 could produce individual low denier tow
products. An individual low denier tow product 30 comprises at least 500 fibers at
a spinning position that is collected into an individual container 160 holding about
20 to 200 lbs of low denier tow product. The means for collecting the individual low
denier tow product comprises a piddle device 524 or a winder (not shown); preferably
a piddle device is used to collect undrawn product into the container 160 in a way
that the product can be stored, transported and withdrawn for further processing.
A wound package on a tube core from a winder is also a container from which the product
can be stored, transported and withdrawn for further processing.
[0070] The new method of operating the staple spinning machine also includes changing the
fiber product characteristics for at least one spinning position making the low denier
product such that the fiber product characteristics differ from the remaining spinning
positions making either the low denier product or the large denier product. Such changed
fiber product characteristics may include a different denier per filament, a different
finish, a different color by direct color injection at the spinning position, a different
filament cross section, or other fiber differences commonly available at an individual
spinning position.
[0071] The new method of operating the staple spinning machine further comprises providing
a means to process the low denier tow product from at least one spinning position
to convert the low denier tow product to a spun yarn product. Such means illustrated
in Figs. 30 and 31 would preferably comprise the stretch break machine 522 of the
invention being supplied from the piddled fiber container 160. Alternatively, the
machine could comprise the '463 reference to Minorikawa or the '778 reference to Adams
or the like which converts continuous filament fiber to discontinuous filament staple
yarn. Each position on the staple fiber spinning machine, such as position 502, could
supply the needs of maybe 10 spinning positions, such as position 526, on a stretch
break machine 522 so that many stretch break machines, such as 522 and 522a, each
with a plurality of positions could be supplied with fiber from a single staple spinning
machine 500.
[0072] The feed yarn 30 can be provided in the piddle container 160 of Figs. 11, 30, and
31 by a piddling device as disclosed in US patent 4,221,345 or it can be provided
by a device as illustrated in Figures 13 and 14. Figure 13 shows a piddler device
236 that comprises a guide roll 238, an idler roll 240, a drive roll 242, an aspirating
jet 244, a fiber distributing rotor 246, a rotor driver 248, a container 250, and
a container oscillator 252. The fiber 30 can come from a staple spinning machine for
continuous man-made filaments, such as the staple spinning machine 501 or 503 in Figs.
30 and 31, respectively. The guide roll 238 guides the fiber to an idler/drive roll
combination, rolls 240 and 242 respectively, where the fiber makes at least one complete
wrap as shown by the arrows 254 and 256 before being fed to the aspirator jet 244
in the direction of arrow 258. The fiber is propelled by a gaseous fluid in the aspirator
jet toward an entrance passage 260 in the rotor 246 which is being rotated continuously
by rotor driver 248. The fiber passes through the rotor 246 and leaves through a passage
exit 262. The fiber then descends in a spiral path 264 into the container 250. As
one portion of the container gradually fills with fiber, the container oscillator
moves the container slowly under the rotor to progressively fill the container with
back and forth layers of spiral-laid fiber. Such a piddle device can operate at speeds
consistent with conventional spinning positions and deposit fiber in a way that it
can be removed from the container at a slow speed consistent with stretch-breaking
speeds.
[0073] Figure 14 shows a detailed cross-section view of the rotor 246, which has a body
266. The entrance passage 260 is located on top of the body 266 at the center of rotation
of body 266, and is connected to the passage exit 262 by an angled passage 268 which
the fiber 30 (Fig. 11) and fluid from aspirating jet 244 (Fig. 13) can easily pass
through. A balancing hole 270 is provided opposite passage exit 262 to balance the
rotor and minimize vibration during rotation.
[0074] The processes as illustrated in Figs. 1, 8 and 9 using the apparatus of Fig. 11 can
produce a staple yarn having a linear density of less than or equal to 1000 denier
or a staple yarn having 500 or less filaments per cross-section. Such a yarn has a
unique distribution of filament lengths when the break zones are operated as described
above to provide a particular stretch broken yarn. The unique stretch-broken yarn
has a particular average filament length, a maximum filament length and a range of
filament lengths. Such a stretch-broken yarn has a useful number of filament ends
per inch. A substantial percentage of these numerous filament ends can be found as
protruding ends extending from the central portion of the yarn to give the yarn a
desirable feel or "hand". In a preferred embodiment, the yarn has a numerical average
filament length (versus a weight average) that is greater than 6 inches, the maximum
length of 99% of the filaments is less than 25 inches, and the middle 98% of the filament
lengths defines a length range that is greater than or equal to the average length.
The range equals the maximum length of the mid 98% samples minus the minimum length
of the mid 98% samples. The yarn can also be characterized as a consolidated, manmade
fiber of discontinuous filaments of different lengths, the filaments intermingled
along the length of the yarn to maintain the unity of the yarn, wherein the average
length, avg, of the filaments is greater than 6 inches, and the fiber has a filament
length distribution characterized by the fact that 5% to less than 15% of the filaments
have a length that is greater than 1.5 times the average length, avg. Preferably,
the filament length distribution also has 5% to less than 15% of the filaments having
a length less than 0.5 times avg.
[0075] Figure 15 illustrates a plot of filament length distribution for a yarn that was
made according to the following process parameters:
- eb = 3.5 feed yarn to draw zone
- eb = 0.247 feed yarn value after draw and entering first break zone
- eb = 0.1 (estimated value entering second break zone)
- L1 = 51.0"; L2 = 16.9"; (L2 = 0.33 L1)
- D1 = 3; D2 = 2; (D2-1)/(D1-1) = 0.5
- draw speed ratio D4 = 4.2
- draw length L4 = 112"
- draw temperature = 188° C over a 12" contact surface
- feed material was one fiber of 9147 denier, 6.6 dpf continuous filament nylon from
a container of piddled fiber.
[0076] The histogram in Fig. 15 represents the actual yarn sample filament length distribution
and is labeled 271. The filament lengths were pulled from the fiber before consolidation
so they could be easily removed. No draft was employed. The filament lengths were
obtained by the process described in US 4,118,921 under the sections entitled "Average
Fiber Length", "Fiber Length Distribution", and "Fiber Length Histogram", hereby incorporated
herein by reference. It was known by denier measurement and calculation that there
were about 192 filaments in the fiber cross-section coming from the second break zone,
so 500 filaments were removed from the new end of fiber and the lengths were recorded
and grouped in one inch increments. The procedure to get this number of filaments
was to repeat the process under "Average Fiber Length" after each batch of 100 filaments.
This resulted in the histogram 271 of fiber length and frequency of Fig. 15. The model
simulation of the process was set up the same as the actual test process to predict
the filament length distribution represented by curve 272 of Fig. 15. As can be seen,
the simulation of the filament length distribution is close to the actual filament
length distribution. For the actual test, the numerical average filament length was
11.0", and for the simulation the average filament length was 11.1". For the actual
test, the length of the middle 98% of filament lengths was from 3" to 18" for a range
of 15". For the simulation, the lengths were from 3.5" to 19.5" for a range of 16".
For the actual test, the maximum length of 99% of the filaments was 18", and for the
simulation, the maximum length was 19.5". Simulation values in these cases were within
10% of the actual values. The number of filaments having a length less than 0.5 times
the average, avg, and the number greater than 1.5 times the average were measured
and simulated. The measured results are 8.2 % less than 0.5 avg and 5.0% greater than
1.5 avg. The simulated results are 11.16% less than 0.5 avg and 10.27% greater than
1.5 avg. These simulation results do not agree as well with the measurements. The
measured results of filament distribution for the upper and lower tails of the distribution
are thought to be statistically unreliable since there were far too few filaments
sampled in the tails of the distribution. In the simulation, 40,000 filaments total
are sampled which includes many tail filaments. In the measured distribution only
500 filaments total were measured which included few tail filaments. Alternatively,
more filaments could be taken in the measured sample. The data in Fig. 15 is also
tabulated in Table I.
[0077] Values of the actual test and simulation fall within the limits of the yarn product
invention as follows:
- average filament length = 11.0 and 11.1 which are ≥ 6"
- mid 98% range = 15" and 16" which are ≥ 11.0" and 11.1 ", respectively
- maximum 99% filament length = 18" and 19.5" which are ≤ 25"
- filament lengths less than 1.5 times avg = 5.0% and 10.27% which are between 5% and
less than 15%
- filament lengths less than 0.5 times avg = 8.2% and 11.16% which are between 5% to
less than 15%
[0078] Table I below illustrates other simulated operating conditions including some comparative
example simulations and shows various ranges of operating parameters that fall within
the limits of the invention. Some actual test with actual and simulated results are
also included.
[0079] Examples CE1 and CE2 are comparative simulation examples operating at a total speed
ratio of Dt = 25. In ex. CE1, the break zone length L1 is 30" and the percentage of
double gripped filaments is low. When the filament distribution of CE1 is plotted
in Figure 16, it is determined that the maximum length of 99% of the filaments is
above 25". In CE2, the break zone length is 10" and the average filament length is
less than 6.0" which is believed to contribute to lower strength yarn when interlacing
is used for consolidation. The filament distribution of CE2 is plotted in Figure 17
where it is seen the maximum length of 99% of the filaments is less than 25" which
is an improvement over ex. CE 1. Since the percentage of double gripped filaments
is low in both comparative examples of single break zones, it is expected there will
be operability problems running these examples. When tests similar to the simulation
conditions were run in single break zones, operability problems occurred at speed
ratios approaching 20 for zone lengths down to 20" long and approaching 5 for zone
lengths at 10" long.
[0080] Examples A, B, C, D, E, and F are simulation examples that were also run at a total
speed ratio of Dt = 25. Example A illustrates a high speed ratio in the second break
zone of D2 = 10 which resulted in a low percentage of double gripped filaments in
the second break zone, although the percentage is more than 50% greater than that
in the single break zones of the comparative examples. Example A1 shows that a reduction
in the second break zone speed ratio and increase in the first break zone ratio results
in a favorable value for (D2-1)/(D1-1) of 2.0. It is expected this would result in
an operability improvement over example A. Example B shows a condition where the first
and second break zones are operated at the same speed ratio of 5. This gives good
results for percentage of double gripped filaments, although the second break zone
has a lower value so operability problems would be more likely there. Example B1 illustrates
that by reducing the second break zone speed ratio and increasing the first break
zone speed ratio one would expect to improve the operability of the second zone so
both zones have the same high percentage of double gripped filaments. The approximated
value of 3.8% is obtained from the plot of Fig. 4 at a value of (D2-1)/(D1-1) of 0.7.
Example C illustrates the effect of a high speed ratio in the first break zone which
reduces the percentage of double gripped filaments there compared to examples A and
B. At the level of D1 = 10, however, the percentage of double gripped filaments is
higher than that in the second break zone when D2 = 10 in example A. This is also
supported by the actual data in Fig. 10A looking at the maximum operability point
157 for the optimum value of (D2-1)/(D1-1) of 0.7. At this point where Dt = 42.8,
the value for D1 is 7.5 and for D2 is 5.7. It appears that operability problems related
to double gripped filaments occur in the second break zone at a lower level of speed
ratio than in the first break zone. The filament distribution for example C is shown
in Figure 18. It has an average length = 6.51" (>= 6"); a mid 98% range = 10" (>=
6.51"); and a maximum 99% filament length = 11.5" (<= 25"). The simulated results
for the number of filaments having a length less than 0.5 times the average and the
number greater than 1.5 times the average are 13.43% less than 0.5 avg and 12.06%
greater than 1.5 avg. This exemplifies the invention and has a good number of filament
ends per inch. Examples D, E, and F show similar results to examples A, B, and C respectively
when using longer first and second break zones L1 and L2. Since L2 = 0.33 L1 in each
case there is little effect on the percentage of double gripped filaments. The average
filament lengths increase as expected.
[0081] Examples G, H, J, and K are simulation examples that were run at a higher total speed
ratio of Dt = 30. Different zone lengths were used, but still L2 = 0.33 L1 for examples
G and H. They compare favorably with examples B and C respectively in terms of percentage
of double gripped filaments, since the increase in Dt was not significant enough to
decrease the percentage much. The filament distribution for example G is shown in
Figure 19. It has a longer average length = 10.1"; a wider mid 98% range = 15"; and
a higher maximum 99% filament length = 17.5", than example C. The simulated results
for the number of filaments having a length less than 0.5 times the average and the
number greater than 1.5 times the average are 15.49% less than 0.5 avg and 14.30%
greater than 1.5 avg. Example G has a correspondingly lower filament ends per inch
than ex. C, although the reduced denier of feed yarn and increased speed ratio also
contribute to the lower value. In examples J and K, L2 = 0.2 L1, but this change is
not enough to make much difference compared to examples B and C respectively.
[0082] Figure 20 shows the process schematic of Figure 9 where a new stretch-broken product
can be made by introducing an additional feed fiber 31a at the downstream end 300
of the draft zone 144 which is the also the upstream end of the consolidation zone
38. Since the fiber 31a will not be subjected to any drafting, the filaments in the
fiber 31 a can be continuous or discontinuous. If continuous filaments are used, they
can be high strength filaments with low elasticity such as an aramid fiber, or they
can be filaments with high elasticity, such as a spandex-type fiber or a 2GT (1,2-ethane
diol (or ethylene glycol) estrified with terephthalic acid) or a 3GT (1,3-propanediol
(or 1,3 propylene glycol)- 3GT (estrified with terephthalic acid) polyester fiber.
A preferred spandex-type fiber is one with elastic filaments having an elongation
to break greater than about 100% and an elastic recovery of at least 30% from an extension
of about 50%. These additional fibers 31a can be added to fibers 30 that preferably
include a polymer such as nylon, polyester, aramid, fluoropolymer or Nomex® (brand
name for a fiber and paper with raw materials of isophthalyl chloride, methpenylene
diamine). Kevlar® aramid fiber of continuous filaments has been combined with polyester
in one product; and Lycra® elastic fiber of continuous filaments has been combined
with polyester in another product.
[0083] Figure 21 shows the process schematic of Figure 9 where a new stretch-broken product
can be made by introducing an additional feed fiber 31b at the downstream end 302
of the draw zone 124 which is also the upstream end of the first break zone 34. This
is useful if fibers 31b which do not require drawing are to be added to drawn fibers
30. Both fibers 30 and 31b would be broken at the same time in the first break zone
34 and would continue to be treated together throughout the remainder of the process.
Such additional fibers 31b are preferably of the polymer group including aramid, fluoropolymer,
and Nomex®, and they are added to fibers 30 that preferably include a polymer from
the group of nylon or polyester.
[0084] Figure 22 shows the process schematic of Figure 9 where a new stretch-broken product
can be made by introducing a first additional feed fiber 31b at the downstream end
302 of the draw zone 124 which is also the upstream end of the first break zone 34;
and also introducing a second additional fiber 3 1 a at the downstream end 300 of
the draft zone 144 which is the also the upstream end of the consolidation zone 38.
This forms a useful combination of fiber features as discussed referring to Figs.
20 and 21. A particularly preferred embodiment is to introduce a fluoropolymer as
the first additional fiber 31b, a spandex-type fiber as the second additional fiber
31a with both additional fibers joining a fiber 30 of polyester. Such a yarn product
is useful as a textile yarn for weaving or knitting socks. Another product combined
discontinuous polyester, as a first feed fiber that was drawn, with a first additional
feed fiber of Kevlar® aramid that is stretch broken with the polyester, and that combination
combined with a second feed fiber of Lycra® elastic fiber of continuous filaments
to form a three component yarn.
[0085] The stretch breaking process of the invention is useful when blending fibers that
may have already been processed to some degree, such as by incorporating color or
a surface treatment that gives the fiber some visual characteristic that can be detected
with the unaided eye. Stretch breaking is a useful way to make specialty yarns without
involving a lot of additional steps, such as is required in conventional staple blending
where the sliver must first be prepared by chopping (cutting), blending, carding,
combing, and the like as was generally illustrated at 516 and 518 in Fig. 29. In this
conventional system, a large quantity of feed fiber must be prepared to make the process
worthwhile, since cleaning the processing equipment after each product run is very
labor intensive and time consuming. In the case of stretch breaking, only a small
amount of feed fiber needs to be prepared for blending with another fiber, and there
is practically no cleanup required to switch to another product blend other than changing
packages in a creel. This is particularly useful in preparing small quantities of
color blended yarn. Referring to Fig. 9, applicants have discovered that by feeding
in a first color fiber 31c that is different than a second feed fiber 31d, a different
color yarn can be produced that is a blend of the two colors. By different colors
is meant two colors that are essentially non-white and non-beige variations, although
one fiber may be a white or beige and the other a distinctly non-white, non-beige
color. The intent is that two distinctly different colors are combined and stretch
broken together and then consolidated to create a new distinct color. ASTM committee
E12, standard E-284 describes a means to distinguish neutral colors, such as white
and beige, based on a lightness measurement with white and beige having a lightness
greater than 90%. It also permits distinguishing color hue and shade to detect color
difference by using CIELAB units where distinctly different colors would have a CIELAB
unit difference of at least 2.0. By blending at least two different colors of fiber,
where only one would have a lightness greater than 90% and the others would have a
color difference in CIELAB units of at least 2.0, creates a new colored yarn from
at least two different feed fibers. The color of the new yarn is distinctly different
than any of the feed fiber colors. When processed further into a cloth-like material,
the blended color shows up as a mild heather look. Other visual differences that can
be blended with applicants stretch breaking process are fibers having a distinct difference
in reflectance, absorbence, wettability, and the like.
[0086] Figure 23 is a schematic elevation view of the process line of Fig. 1 that illustrates
addition of an annealing zone 124a after the consolidation zone 38. The annealing
zone was discussed previously when referring to the draw zone 124 with heating means
140 shown in Figure 8 that is used without a substantial speed change ratio. This
may be useful in a process where the final shrinkage of the yarn must be controlled
to a specified value and annealing after formation of the yarn is the most direct
way to accomplish this. It may also be useful when the feed fiber consists of two
different fibers and the annealing heat treatment causes each fiber in the yarn to
respond differently to create a special effect yarn, as when the shrinkages of the
fibers are different and the differential shrinkage produces a bulky or loopy yarn.
[0087] Figure 24 shows a photomicrograph of a filament from a novel stretch broken product
having the end 304 of each filament split as a result of the stretch breaking process.
The feed fiber is a manmade fiber comprising continuous polyester filaments that is
known by the E.I. DuPont trademark of Coolmax® and is describe in U.S. 3,914,488 to
Gorrafa and 5,736,243 to Aneja. Referring also to Figure 25, which shows a cross-section
of the filament, the filament has a width 306 and, within that width, a plurality
of thick portions 308, 310, and 312 that are connected by thin portions 314 and 316.
It is believed that the stretch breaking process causes the thin portions 314 and
316 to become severed at the ends of the filaments when the filaments break. The severing
occurs for a length 318 of at least about three filament widths so one or more of
the thick portions, such as portion 308, are split apart from the other thick portions,
such as portions 310 and 312, at the ends of the filaments. This is believed to result
in the appearance and feel of having more filament ends in the yarn, which improves
the "hand" of a fabric made from the yarn.
[0088] Table II illustrates various products made following the teachings of the invention,
in general practicing the process illustrated in Fig. 9 using the apparatus in Fig.
11. Feed material deniers totaling about 1,500 - 20,000 produce yarns with deniers
from about 100 - 400. Fibers that are drawn in the process are usually fully drawn
so that the elongation to break going into the first break zone is about 10%.
[0089] Test 1 shows a process condition for making a nylon yarn having a final denier of
137. The process had a draw zone, a first break zone, a second break zone, a draft
zone, and a consolidation zone similar to the process in Fig. 9. The feed yarn came
from a piddle container as at 160 in Fig. 11 (and designated P in the Table II) and
the final yarn product was wound up on a winder as at 222 in Fig. 11. The consolidation
jet 83a (Figs. 9 and 26) had a fluid orifice with angle 340 at 60 degrees in the direction
of yarn travel that was the same for all tests using this jet 83a. The jet exterior
surface 328 is spaced from the nip between rolls 150 and 152 of roll set 148 by a
distance of about 6.0 inches. It is believed this process produced a yarn having the
characteristics of the invention with an average filament length greater than or equal
to 6", the maximum length of 99% of the filaments is less than 25", and the middle
98% of the filament lengths defines a length range value that is greater than or equal
to the value of the average filament length; and wherein 5% to less than 15% of the
filaments were greater in length than 1.5 times the average filament length.
[0090] Test 2 shows a process condition similar to test 1 which has a draw zone, a first
break zone, and a second break zone approximately the same as that used to make the
product illustrated in Fig. 15. The product was completed by processing the fiber
further in a draft zone and a consolidation zone to form a 209 denier yarn. This product
would be expected to have a filament distribution similar to that shown in Fig. 15.
[0091] Test 3 shows a product made using a polymer that has an interfilament friction coefficient
less that 0.1 which is a fluoropolymer made by E. I. DuPont de Nemours & Company (hereinafter
"DuPont") under the trade name Teflon®. The process produced a staple Teflon® product
which is difficult to produce economically by other means. An "omega" wrap as depicted
in Fig. 1A was used on the roll sets 50a, 62a, and 148a of Fig. 11 to control slippage
of the fiber in the roll sets. The feed fiber was supplied from a wound package 162
as in Fig. 11 (designated W in the Table II). The process differed from test 1 in
that the fiber was not heated or drawn in the draw zone. It is believed this product
has an average filament length greater than 6.0 inches and other characteristics similar
to those of test 1.
[0092] Test 4 shows a product made by a process similar to that illustrated in Fig. 21 where
a high strength aramid fiber (DuPont trademark Kevlar®) was fed in upstream of the
roll set 42 (42a in Fig. 11) after the polyester fiber (DuPont trademark Dacron®)
was drawn. The aramid and polyester were then stretch broken, drafted, and consolidated
together to produce a blended yarn with a 397 denier. An "omega" wrap as depicted
in Fig. 1A was used on the roll sets 50a, 62a, and 148a of Fig. 11 to control slippage
of the fiber in the roll sets since the aramid fiber required a high force to break.
It is believed this product has filament length characteristics similar to those of
test 1.
[0093] Test 5 shows a product made by a process similar to that in test 3 where an aramid
fiber (DuPont trademark Kevlar®) and a fluoropolymer (DuPont trademark Teflon®) fiber
were fed in together and were neither heated nor drawn in the draw zone; the draw
zone was only used as a convenient way to transport the fibers to the first break
zone. The Kevlar® and Teflon® were then stretch broken, drafted, and consolidated
together to produce a blended yarn with a 274 denier. An "omega" wrap as depicted
in Fig. 1A was used on the roll sets 50a, 62a, and 148a of Fig. 11 to control slippage
of the fiber in the roll sets since the aramid fiber required a high force to break
and the fluoropolymer required more surface contact to avoid slippage. Such a yarn
is useful for making reinforcing fabric useful in industrial timing belts where high
strength and low wear friction are valued. It is believed this product has filament
length characteristics similar to those of test 1.
[0094] Test 6 shows a product made by a process similar to that in test 5 where an aramid
fiber (DuPont trademark Kevlar®) and a high temperature fiber (DuPont trademark Nomex®)
were fed in together and were neither heated nor drawn in the draw zone; the draw
zone was only used as a convenient way to transport the fibers to the first break
zone. The Kevlar® and Nomex® were then stretch broken, drafted, and consolidated together
to produce a blended yarn with a 230 denier. An "omega" wrap as depicted in Fig. 1A
was used on the roll sets 50a, 62a, and 148a of Fig. 11 to control slippage of the
fiber in the roll sets since the aramid fiber required a high force to break. It is
believed this product has filament length characteristics similar to those of test
1.
[0095] Test 7 shows a product made by a process similar to that in test 3 where an aramid
fiber (DuPont trademark Kevlar®) was fed in and was neither heated nor drawn in the
draw zone; the draw zone was only used as a convenient way to transport the fiber
to the first break zone. An "omega" wrap was used. A Kevlar® yarn with a low denier
of 101 was produced that would be difficult to produce economically by other means.
It is believed this product has filament length characteristics similar to those of
test 1.
[0096] Test 8 shows a product made by a process similar to that illustrated in test 4 except
a fluoropolymer fiber (DuPont trademark Teflon®) was fed in upstream of the roll set
42 (42a in Fig. 11) after the polyester fiber (DuPont trademark Dacron®) was drawn.
The fluoropolymer and polyester were then stretch broken, drafted, and consolidated
together to produce a blended yarn with a 278 denier. Such a product may be useful
for making socks that minimize the formation of blisters on the wearer's feet. It
is believed this product has filament length characteristics similar to those of test
1.
[0097] Test 9 shows a process similar to that in test 1 except a polyester fiber is used.
A yarn is made having a denier of 274. It is believed this product has filament length
characteristics similar to those of test 1.
[0098] Test 10 shows a product made by a process similar to that illustrated in Fig. 20,
where a continuous filament elastic fiber (DuPont trademark Lycra®) was fed in upstream
of the roll set 148 (148a in Fig. 11) after the polyester fiber (DuPont trademark
Dacron®) was drawn, stretch broken, and drafted. The Lycra® was tensioned to extend
it about 100% before joining the Dacron® fiber and being consolidated together, with
the Lycra® filaments remaining continuous. When the finished yarn was held under no
tension, the Lycra® contracted and created a bulky loopy yarn that was highly elastic.
[0099] Test 11 shows a process similar to that in test 9, except the polyester filaments
had a cross-section like that illustrated in Fig. 25, and a 277 denier yarn having
split ends as in Fig. 24 was produced. It is believed this product has filament length
characteristics similar to those of test 1.
[0100] Test 12 shows a process similar to that in test 1, except the feed fiber consisted
of two different fibers, each a different color. The colored fibers were combined
before drawing and were drawn and stretch broken together as a single bundle of fiber.
The first fiber was a distinct pink color and the second was a distinct purple color.
It is believed these two colors would each be non-neutral colors having a lightness
less than 90%, and they would have a color difference of at least 2.0 CIELAB units.
The resultant yarn had a color distinctly different than either of the feed fiber
colors and it is believed that when this yarn would be woven into a fabric, the fabric
would have a heather look.
[0101] Test 13 shows a process similar to test 12, except the pink colored fiber was replaced
with a light gray fiber that it is believed would be a neutral color having a lightness
of greater than 90%. The resultant yarn had a color distinctly different than either
of the feed colors and the yarn itself had a distinct heather look.
[0102] Test 14 shows a process similar to that of Fig. 20 where a first feed fiber of Kevlar®
was stretch broken (as in test 7) and a second fiber of continuous filament Kevlar®
was fed in just upstream of roll set 148a in Fig. 11. The continuous filaments were
consolidated with the discontinuous stretch broken filaments of Kevlar® to form a
reinforced staple yarn having a denier of 311.
[0103] Test 15 shows a process similar to that in Fig. 22 where a Teflon fiber is fed in
upstream of roll set 42 (42a in Fig. 11) (as in test 8) and a Lycra® fiber is fed
in upstream of roll set 148 (148a in Fig. 11). The Teflon fiber is stretch broken,
and drafted with the drawn Dacron® fiber and this blended discontinuous filament fiber
is consolidated with the continuous filament Lycra® fiber as was discussed in test
10. This makes a stretchy, bulky, low friction yarn that would be useful in stretch
socks that minimize blistering.
[0104] Test 16 shows a process similar to test 1 where two separate feed fibers were supplied
to the process to create a large denier feed fiber of close to 20,000 denier going
into the draw zone. In the draw zone two temperature zones were used on the heater
140 of Fig. 11. A first zone consisted of a 24 inch length at 100° C followed by a
second zone of a 12 inch length at 188° C. A total process speed ratio of over 70X
produced a yarn of 277 denier.
[0105] Test 17 illustrates a product made following the teachings of the invention, in particular
practicing the process illustrated in Fig. 8 using the apparatus in Fig. 11. To set
up the process of Fig, 8 using the apparatus of Fig. 11 involved removing the drafting
zone 144 and roll set 148a in Fig. 11 and moving the consolidation zone 38 into place
adjacent roll set 62a since the process of Fig. 8 does not use a drafting zone. The
consolidation device of Fig. 28 was used, alternatively referred to as a tandem jet
device, and the process was operated at a total draw of 48 to make a 192 denier product
that demonstrates a low L2/L1 ratio of 0.25. Table III tabulates the tandem jet parameters.
[0106] Test 18 is the same process as test 17 except the interlace jet of Figs. 26 and 27
was used. The feed yarn consisted of two tows each of 6280 denier black colored nylon
that were combined before the draw zone and resulted in a final yarn denier of 186.
The process operated at a total draw of 67.4 for a high output speed of 303 ypm that
is close to the speed limitations of the machine used for the test. It is expected
that higher speeds exceeding 500 ypm could be achieved using the process of the invention
and a higher speed machine.
[0107] Test 19 shows results similar to test 18 where the final output speed was 269 ypm
making a 198 denier Dacron® product.
[0108] Tests 20, 21, 22, and 23 were run with a setup similar to test 17 to examine the
preferred distance "a" between the nozzles of the consolidation device of Fig. 28.
Each test was set up to produce a yarn with a different average filament length as
determined by simulation. For each average filament length, several runs were made
where the distance "a" between the nozzles of the consolidation device was varied
by leaving the first nozzle, N1, in place at a distance of 1.72 inches to where the
fluid passages intersect the fiber bore; the second nozzle was moved to various positions
and a consolidated yarn sample was collected. The sample for each position was measured
for strength using a Lea Product process and the strength was recorded in grams per
denier for each position of the second nozzle.
[0109] Test 20 was set up to produce a yarn with an average filament length of 8.9 inches
as determined by simulation. The results were plotted in Figure 35 as the curve labeled
8.9. The maximum strength occurred at a nozzle spacing "a" of 9.2 inches as recorded
in Table III for test 20. This gave a ratio of a/avg of 1.03. A simulation of the
filament distribution was also run for the conditions used in this test and are displayed
in Table I for test 20. The simulation indicated the distribution of filaments greater
than 1.5 times the average filament length could be expected to be 12.4%; the distribution
of filaments less than 0.5 times the average filament length could be expected to
be 14.7%.
[0110] Test 21 was run the same as test 20 except the break zone lengths were changed to
produce a yarn made of Dacron® polyester fiber with an average filament length of
17.5 inches. This set of conditions also was run with a high L2/L1 ratio of 0.58.
The results were plotted in Figure 35 as the curve labeled 17.5. The maximum strength
occurred at a nozzle spacing "a" of 13.0 inches as recorded in Table III for test
21. This gave a ratio of a/avg of 0.74. A simulation of the filament distribution
was also run for the conditions used in this test and are displayed in Table I for
test 21. The simulation indicated the distribution of filaments greater than 1.5 times
the average filament length could be expected to be 12.4%; the distribution of filaments
less than 0.5 times the average filament length could be expected to be 13.9%.
[0111] Test 22 was run the same as test 20 except the break zone lengths were changed to
produce a yarn made of Dacron® polyester fiber with an average filament length of
6.4 inches. The results were plotted in Figure 35 as the curve labeled 6.4. There
was not a distinct value for the maximum strength; the curve was essentially flat
except for a dip down to a strength of about 0.8 which was an estimated value since
the sample made at this distance of about 4 inches was so weak a full size skein could
not be wound for the standard Lea Product test. Either the nozzle spacing is not determinative
of strength at a low average length for the filaments or there was an unexplained
problem with the test. A simulation of the filament distribution was also run for
the conditions used in this test and are displayed in Table I for test 22. The simulation
indicated the distribution of filaments greater than 1.5 times the average filament
length could be expected to be 12.3%; the distribution of filaments less than 0.5
times the average filament length could be expected to be 13.9%.
[0112] Test 23 was run without breaking the fiber in the first break zone and only breaking
it in the second zone to simulate a single break zone process. It was set up to produce
a yarn with an average filament length of 8.0 inches. The results were plotted in
Figure 35 as the curve labeled 8.0. The maximum strength occurred at a nozzle spacing
"a" of 12.2 inches as recorded in Table III for test 23. This gave a ratio of a/avg
of 1.53. A simulation of the filament distribution was also run for the conditions
used in this test and are displayed in Table I for test 23. The simulation indicated
the distribution of filaments greater than 1.5 times the average filament length could
be expected to be 18.4%; the distribution of filaments less than 0.5 times the average
filament length could be expected to be 18.3%. This product made with a single break
zone has product characteristics that fall outside the limits of the invention using
two break zones, but it shows that the nozzle spacing has an optimum value for best
yarn strength and the nozzle spacing invention is effective with a variety of processes
that make a yarn with an average filament length greater than 6 inches.
[0113] Looking at the results of tests 20, 21, 22, and 23, the value for the spacing "a"
between the first nozzle and second nozzle ranges from 0.74 to 1.53 , or about 0.5
to 2.0 times the average filament length for fibers/yarns with an average filament
length greater than about 6.0 inches. Taking the three values of "a" and averaging
them, the preferred value for "a" is about 1.1 times the average filament length.
Although test 22 did not have a point of maximum strength, it did have a point of
diminished strength that could be avoided in the set up of the process if the teachings
of the invention were followed and the nozzles were set to the preferred value of
1.1 avg. This would result in a value of "a" of 1.1 x 6.4 = 7.0 inches. This avoids
the 5.0 inch position of diminished strength.
[0114] Test 24 was run with a setup similar to test 17 using the consolidation device of
Fig. 28 and the L2/L1 ratio was run at 0.35 to produce a yarn with an average filament
length of 6.7 inches.
[0115] Test 25 uses a process similar to that in test 17. The feed material in test 21 is
a bicomponent elastic yarn wherein each filament has a circular cross section with
one half of the cross-section comprising 2GT polyester and the other half cross-section
comprising 3GT polyester. Such a feed material is described in U.S. Patent 3, 671,
379 to Evans et al., hereby incorporated herein by reference. Related patents to others
are 3,562,093; 3,454,460; and 2,439, 815. The two different polymers in the cross-section
have different shrinkage characteristics after spinning so that after heat treatment,
the fiber becomes a crimped fiber where the filaments curls into a coiled springy
structure. Before heat treatment to activate the fiber latent elasticity, the fiber
still has a significant amount of elasticity or crimp, which has caused a problem
in the past making staple yarn using conventional combing and carding equipment. As
a result, it is believed that staple yarn of bicomponent fiber is not known in the
textile trade. The resultant multifilament yarn is very springy and has a substantial
elasticity from no tension to a maximum tension, where all the elasticity is removed
without plastic deformation of the filaments. This elasticity is characterized as
percent crimp development, CD, that can be developed with wet heat and measured following
the guidelines in the '379 and '460 reference above. The finished yarn must be heat
treated after stretch breaking to recover its latent elasticity and obtain its final
elastic characteristics.
[0116] Test 25 shows a process condition for making a bicomponent yarn of 2GT polyester
and 3GT polyester components (designated BC23) having a final denier of 160. The process
has a heat treating zone, a first break zone, a second break zone, and a consolidation
zone similar to the process in Fig. 8; a draft zone is not used. The feed yarn comes
from 12 wound packages of 100 denier yarn each similar to 162 in Fig. 11. The feed
yarn is pre-drawn, but has not been heat treated to develop the latent elasticity
of the fiber, although the fiber possesses some partial elasticity or crimp. The final
yarn product was wound up on a winder 222 shown in Fig. 11. The consolidation device
used is the tandem jet type in Fig 28. The tensioner at 164 was adjusted to provide
enough tension on the feed yarn so that all of the partial stretch (crimp) was removed
from the feed yarn at roll 168. The yarn is heated treated to a temperature of 180°
C by fiber heater 140 while maintaining tension, but without drawing the filaments.
Although the fiber was not drawn in draw zone 124, it was surprisingly necessary to
heat the fiber to maintain good operability in the break zones. The yarn was stretch
broken and rebroken in zones D1 and D2 and was then forwarded to the consolidation
jet 83b without drafting to form a yarn of 160 denier. The yarn was then wound on
a package as at 222 with enough tension that the stretch in the yarn was substantially
removed. To develop the elastic character of the yarn it is necessary for the yarn
to undergo heating to about 100 degrees C to form a helically coiled elastic yarn
structure (having crimp and curl) having good bulk and elastic recovery. Such heating
may be accomplished in a separate step or the yarn may be woven into a fabric and
the heat supplied by the dying process for the fabric. The crimped discontinuous filament
yarn is believed to have a crimp development of from about 35-40% as measured according
to the procedure described in the '379 referenced patent to Evans et al. It is believed
that this process produces a yarn where the crimp and curl are deregistered due to
the random breaking of the filaments so this yarn would be very useful in making a
stretch staple fabric with low "orange peel" (a fabric surface with a mottled look
like the surface of an orange). Fabrics made with crimped or curled yarn, which has
not been deregistered frequently, possess orange peel.
[0117] Test 26 shows a process condition for making a bicomponent yarn of 2GT and 3GT components
(BC23) with a 50:50 ratio of components and the consolidated yarn having a final denier
of 176. The process has a drawing and heat treating (annealing) zone, a first break
zone, a second break zone, and a consolidation zone similar to the process in Fig.
8; a draft zone is not used. The feed yarn comes from 24 wound packages to make up
a 4714 denier undrawn yarn. The final yarn product was wound up on a winder as at
222 in Fig. 11. The consolidation interlace jet 83a (Fig. 26 and 27) had a fluid inlet
orifice angled at 60 degrees in the direction of yarn travel. The tensioner at 164
was adjusted to provide enough tension on the feed yarn so that all of the stretch
was removed from the feed yarn at roll 168. The yarn is drawn at a temperature of
160° C by fiber heater 140 while undergoing a draw ratio of 3.0X. The yarn was stretch
broken and rebroken in zones D1 and D2 and was then forwarded to the consolidation
jet 83a without drafting to form a yarn of 176 denier. The yarn was then wound on
a package as at 222 (Fig. 11). If the yarn was heat treated with (hot air or) steam
to raise the temperature to 100° C which would served to redevelop the shrinkage and
curl in the filaments the yarn would be expected have a CD of about 50-60%. This is
slightly higher than what would be expected with the yarn from test 25 that was consolidated
with the tandem jet arrangement that makes a fasciated yarn. If the same fiber had
only been drawn and not stretch broken, it is believed it would have a CD of about
55-65% that is only slightly higher than the staple fiber yarn of the invention which
has more desireable hand than a continuous filament bicomponent yarn.
[0118] The results of test 24 and 25 are surprising in that a staple stretch broken yarn
can be made with good runnability from either pre-drawn or undrawn fiber by first
removing all feed yarn stretch with pretension, and then heating the yarn to anneal
both the pre-drawn or just-drawn fiber before stretch breaking the filaments. The
stretch characteristics of the feed yarn are substantially retained in the finished
staple yarn.
[0119] It is believed that other elastic fibers, i.e. crimped fibers, can also be successfully
processed using the teachings of the invention. Other fibers may comprise different
polymer combinations, such as a different nylon polymers, or different structures,
such as biconstituent fibers. A biconstituent fiber is typically one with a core polymer
that is highly elastic (or "soft"), such as a Lycra® elastomer, that has "wings" of
an inelastic ("hard") polymer attached as longitudinal ribs during the spinning process.
After spinning, the latent elasticity of the fiber can be activated by heat that causes
the soft core polymer to shrink considerably more than the hard wing polymer which
causes the composite structure to helically coil up to look like a screw thread. This
fiber structure also has some "crimp" after spinning and drawing and before heat treating,
similar to the bicomponent fiber. Polymer pairs should be compatible so they stick
together, and can be cospun. For that, they have to have a similar thermal response
and functional spinning viscosity. Useful pairs are therefore usually pretty similar
chemically, or have some specific interaction. Common bicomponents are two polyesters,
two nylons, etc., while the biconstituents are e.g. 4GT/4GT-4GO (HYTREL®) and nylon/PEBAX®;
homopolymer/block copolymer pairs in which one block of the copolymer is the same
as the homopolymer. Ratios can vary considerably, but are generally limited to somewhere
between 80/20 and 20/80, preferably 70/30 to 30/70. Other conventional crimped fibers,
such as those crimped by jets, gear crimpers, stuffer box crimpers and the like could
also be converted to a staple yarn using the process of the invention.
[0120] It is, therefore apparent that there has been provided in accordance with the present
invention, methods for stretch-breaking continuous filament fibers to form discontinuous
filament fibers and consolidating these fibers into yarns, that fully satisfies the
aims and advantages hereinbefore set forth. While this invention has been described
in conjunction with a specific embodiment thereof, it is evident that many alternatives,
modifications, and variations will be apparent to those skilled in the art. Accordingly,
it is intended to embrace all such alternatives, modifications and variations that
fall within the spirit and broad scope of the appended claims.
1. A stretch-break process for producing a staple yarn from fiber comprising filaments
fed into a continuous operation comprising:
breaking the filaments in a first break zone by increasing the fiber speed within
a first break zone length at a first speed ratio D1 greater than or equal to 2;
breaking the filaments in a second break zone located downstream from the first break
zone by increasing the fiber speed within a second break zone length at a second speed
ratio D2 greater than or equal to 2 and wherein a relationship (D2 - 1)/(D1- 1) ranges
from 0.15 to 2.5, and wherein a relationship L2/L1 ranges from 0.2 to less than 0.4;
and
consolidating the fiber in a consolidation zone downstream from the second break zone
to form a staple yarn.
2. A stretch-break process for producing a staple yarn from fiber comprising filaments
fed into a continuous operation comprising:
breaking the filaments in a first break zone by increasing the fiber speed within
a first break zone length at a first speed ratio D1 greater than or equal to 2 and
wherein the first break zone length is greater than or equal to 20.0 inches;
breaking the filaments in a second break zone located downstream from the first break
zone by increasing the fiber speed within a second break zone length at a second speed
ratio D2 greater than or equal to 2 and wherein a relationship (D2 - 1)/(D1 - 1) ranges
from 0.15 to 2.5, and wherein a relationship L2/L 1 ranges from 0.2 to 0.6 and L1
is at least 20.0 inches; and
consolidating the fiber in a consolidation zone downstream from the second break zone
to form a staple yarn.
3. A process as recited in claim 2 wherein the relationship (D2 - 1)/(D1 - 1) comprises
a range of 0.2 to 2.0 and the relationship L2/L1 has an upper limit that is less than
0.4.
4. A process as recited in claim 2, further comprising drawing the fiber in a draw zone
upstream from the first break zone by increasing the fiber speed within a predetermined
draw zone length.
5. A process as recited in claim 4, wherein drawing the fiber comprises heating the fiber.
6. The process of claim 5, wherein the filaments fed into the operation are from the
group comprising undrawn or partially drawn bicomponent filament structures and biconstituent
filament structures.
7. A process as recited in claim 4, further comprising drafting the fiber in a draft
zone upstream from the consolidation zone.
8. A process as recited in claim 7, further comprising feeding additional fiber into
the process upstream of a zone selected from the group consisting of the first break
zone, the second break zone, the draft zone, and the consolidation zone.
9. A process as recited in claim 8, wherein feeding additional fiber comprises feeding
a first additional fiber into the process at the upstream end of the first break zone
and feeding a second additional fiber of continuous filaments into the process at
the upstream end of the consolidation zone.
10. A process as recited in claim 2, further comprising drafting the fiber in a draft
zone upstream from the consolidation zone.
11. A process as recited in claim 2, further comprising drafting the fiber in a draft
zone, which is coincident with the consolidation zone.
12. A process as recited in claim 2, further comprising annealing the fiber in an annealing
zone by heating the fiber within a predetermined annealing zone length.
13. The process of claim 12, wherein the filaments fed into the operation comprise partially
drawn and fully drawn crimped structures.
14. A stretch-break process for producing a staple yarn from fiber comprising filaments
fed into a continuous operation comprising:
breaking the filaments in a first break zone between cylindrical entrance nip rolls
and exit nip rolls, the exit nip rolls each having ends with a width therebetween,
increasing the fiber speed within a first break zone length L1 at a first speed ratio
D1 greater than or equal to 2 thereby creating a fiber having a core of closely gathered
filaments and loose filament ends extending from the core;
gathering the loose filament ends in the first break zone and adjacent the exit nip
rolls and directing them toward the fiber core so the loose ends in all directions
around the core are constrained to be within a distance from the center of core of
not greater than the distance of the center of the core from each respective end of
the exit rolls for the first break zone;
breaking the filaments in a second break zone located downstream from the first break
zone by increasing the fiber speed within a second break zone length L2 at a second
speed ratio D2 greater than or equal to 2 and wherein a relationship (D2 - 1)/(D1
- 1) ranges from 0.15 to 2.5, and wherein a relationship L2/L1 ranges from 0.2 to
0.6; and
consolidating the fiber in a consolidation zone downstream from the second break zone
to form a staple yarn.
15. The process of claim 14, wherein gathering the loose filament ends comprises passing
the fiber through a bore and creating a spiral fluid flow path in the bore to loosely
wrap the loose filament ends around the core.
16. The process of claim 14, wherein gathering the loose filament ends comprises passing
the fiber through a trough having side walls to loosely contain the loose filament
ends extending laterally toward the nip roll ends around the core.
17. The process of claim 14, wherein breaking the filaments in a second break zone occurs
between cylindrical entrance nip rolls and exit nip rolls, the exit nip rolls of the
second break zone each having ends with a width therebetween, creating a fiber in
the second break zone having a core of closely gathered filaments and loose filament
ends extending from the core; and
further comprising gathering the loose filament ends in the second break zone and
adjacent the exit nip rolls of the second break zone; and
directing the loose filament ends toward the fiber core such that the loose filament
ends in all directions around the core are constrained being within a distance from
the center of core of not greater than the distance of the center of the core from
each respective end of the exit nip rolls for the second break zone.
18. A stretch-break process for producing a staple yarn from fiber comprising filaments
fed into a continuous operation comprising:
breaking the filaments in a first break zone by increasing the fiber speed within
a first break zone length at a first speed ratio D1 greater than or equal to 2, the
first break zone having a length greater than 20.0 inches;
breaking the filaments in a second break zone located downstream from the first break
zone by increasing the fiber speed within a second break zone length L2 at a second
speed ratio D2 greater than or equal to 2 having a relationship (D2 - 1)/(D1 - 1)
ranges from 0.15 to 2.5, and having a relationship L2/L ranging from 0.2 to 0.6, forming
a fiber of discontinuous filaments having an average length "avg"; and
consolidating the fiber in a consolidation zone downstream from the second break zone
to form a staple yarn by passing the fiber through the nip of a pair of cylindrical
rolls and then through a first bore in a first nozzle that provides a jet of fluid
through a channel into the first bore in a first spiral direction around the fiber
to twist the loose filaments around the fiber core, the first nozzle having an entrance
end adjacent the nip of said feed rolls, and then passing the fiber through a second
bore in a second nozzle that provides a jet of fluid through a channel into the second
bore in a second spiral direction around the fibers to false twist the fiber core,
the second spiral direction opposite from the first, the channel in the second bore
of the second nozzle spaced from the channel in the first bore of the first nozzle
by a distance "a", where 0.5avg < a < 2.0avg.
19. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along the length of the yarn to maintain the unity
of the yarn, wherein the average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length distribution characterized by the fact that 5% to less than 15% of the filaments have a length that is greater
than 1.5avg.
20. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein the average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length distribution of 5% to less than 15% of the filaments
having a length less than 0.5avg, and that 5% to less than 15% of the filaments have
a length that is greater than 1.5avg.
21. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length of the filaments is greater than 6 inches,
and the fiber includes continuous filaments intermingled with the discontinuous filaments
along the length of the yarn, the continuous filaments having less than 10% elongation
to break.
22. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length of the filaments is greater than 6 inches,
and wherein the fiber includes continuous filaments intermingled with the discontinuous
filaments along the length of the yarn, the continuous filaments comprising elastic
filaments having an elongation to break greater than about 100% and an elastic recovery
of at least 30% from an extension of 50%.
23. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length of the filaments is greater than 6 inches,
and at least 1% of the discontinuous filaments in the yarn by denier comprises a fiber
having a filament-to-filament coefficient of friction of 0.1 or less.
24. A yarn as recited in claim 23, wherein the at least 1% of the yarn by denier comprises
a fluoropolymer.
25. A yarn as recited in claim 23, further comprising continuous filaments intermingled
with the discontinuous filaments along the length of the yarn.
26. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length of 5% to less than 15% of the filaments having
a length greater than 1.5avg and at least 1% of the discontinuous filaments in the
yarn have a filament cross-section having a width and a plurality of thick portions
connected by thin portions within the filament width, and the thin portions at the
ends of the discontinuous filaments are severed so the thick portions are separated
for a length of at least about three filament widths to thereby form split ends on
the filaments.
27. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length, avg, of the filaments is greater than 6 inches,
and the fiber has a filament length distribution of 5% to less than 15% of the filaments
having a length that is greater than 1.5avg, and the fiber in the yarn comprising
two fibers that have visually distinct differences detectable by an unaided eye.
28. The yarn of claim 27, wherein the differences comprise a difference in colors, the
colors of the fibers excluding neutral colors having a lightness greater than 90%,
and the colors of the fibers having a color difference of at least 2.0 CIELAB units,
the lightness and color difference measured according to ASTM committee E12, standard
E-284, to form a multicolored yarn.
29. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length, avg, of the filaments is greater than 6 inches,
and at least 1% of the discontinuous filaments in the yarn by denier comprises a fiber
having filaments with a latent elasticity of 30% or more.
30. The yarn of claim 29, wherein the at least 1% of the discontinuous filaments in the
yarn by denier is a bicomponent yarn comprising a first component of 2GT polyester
and a second component of 3GT polyester.
31. A yarn comprising a consolidated, manmade fiber of discontinuous filaments of different
lengths, the filaments intermingled along a length of the yarn to maintain a unity
of the yarn, wherein an average length, avg, of the filaments is greater than 6 inches
and the fiber has a filament length distribution of 5% to less than 15% of the filaments
having a length greater than 1.5avg, and at least 1% of the discontinuous filaments
in the yarn by denier comprises a fiber having filaments with a latent elasticity
of 30% or more.
32. In the method of operating a staple fiber spinning machine having a single polymer
supply system feeding at least 10 spinning positions normally combined together to
make a single large denier tow product collected into a container, wherein the improvement
comprises:
managing the operation of the spinning machine, spinning at least 500 fibers at a
spinning position, to simultaneously produce a plurality of products, having an individual
lot size of 20 to 200 lbs, collected into a container, the lot size being smaller
than a lot size of the single large denier tow product; and
providing at least two spinning position with a means for collecting tow from the
at least ten spinning positions into containers making a low denier tow product.
33. The method of claim 32, wherein the means for collecting tow comprises a piddle device
or a winder.
34. The method of claim 32, further comprising changing the product characteristics for
at least one spinning position making the low denier product such that the product
characteristics differ from other spinning positions on the spinning machine.
35. The method of claim 32, further comprising providing a means to process the low denier
tow product from the at least two spinning position to convert the low denier tow
product to a spun yarn product.
36. The method of claim 35, wherein the means for collecting tow comprises a piddle device.
37. The method of claim 35, wherein the means to process the low denier tow product to
convert it to a yarn comprises stretch breaking the fiber in at least two zones and
consolidating the fiber to make a yarn product.
38. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
the continuous filaments in a break zone between cylindrical entrance nip rolls and
exit nip rolls, the exit nip rolls each having ends with a width therebetween, by
increasing the fiber speed within the break zone creating a discontinuous filament
fiber having a core of closely gathered filaments and loose filament ends extending
from the core, the break zone also drafting the fiber, and consolidating the discontinuous
filaments to form a yarn, wherein the improvement comprises:
gathering the loose filament ends in the break zone and adjacent the exit nip rolls
and directing them toward the fiber core such that the loose ends in the lateral directions
around the core are constrained to be within a distance from the center of the core
of not greater than the distance of the center of the core from each respective end
of the exit nip rolls for the break zone to minimize wrapping of the loose ends on
the exit nip rolls; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
39. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
all the continuous filaments in a break zone by increasing the fiber speed within
the break zone thereby creating a discontinuous filament fiber, the break zone also
drafting the fiber, and consolidating the discontinuous filaments in a consolidation
zone to form a yarn, the fiber following a substantially straight path through each
functional zone, each functional zone path defining a unit path vector having a head
in the direction of fiber travel and a tail, wherein the improvement comprises:
arranging the path of the fiber through the functional zones to be folded such that
a path vector in a first functional zone being placed tail to tail with a path vector
in a next sequential functional zone defines an included angle that is between 45
degrees and 180 degrees resulting in a compact floor space for the process; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, such that the discontinuous filament yarn has been reduced
to less than 500 filaments in any cross-section of the yarn.
40. The process of claim 39, wherein the path vector of the fiber in the break zone extends
in one direction and the path vector of the fiber in the consolidation zone is folded
to extend in a direction substantially 180 degrees opposite to the path in the break
zone.
41. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
all the continuous filaments in a first break zone between cylindrical entrance nip
rolls and exit nip rolls, by increasing the fiber speed within the break zone creating
a discontinuous filament fiber, the first break zone including drafting the fiber,
breaking the discontinuous filaments in a second break zone between cylindrical entrance
nip rolls and exit nip rolls, by increasing the fiber speed within the second break
zone, the second break zone including drafting the fiber, and consolidating the discontinuous
filaments to form a yarn, wherein the improvement comprises:
arranging the path of the discontinuous filament fiber at the exit of the first break
zone and at the entrance and exit of the second break zone to first contact the fiber
to an electrically conductive nip roll before contacting the fiber to an electrically
non-conductive nip roll and to only separate the fiber from an electrically non-conductive
nip roll by first separating the fiber from the electrically non-conductive nip roll
before separating it from an electrically conductive nip roll to thereby minimize
static buildup in the fiber as it passes through the nip rolls;
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
42. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
the continuous filaments in a break zone by increasing the fiber speed within the
break zone thereby creating a discontinuous filament fiber, the break zone including
drafting the fiber, and consolidating the discontinuous filaments in a consolidation
zone to form a yarn, wherein the improvement comprises:
feeding at least two different fibers into the process and combining them before breaking
in the break zone, the fiber differences being visually distinct differences detectable
by an unaided eye; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
43. The process of claim 42, wherein the difference between fibers is color, the colors
of all but one of the fibers excluding neutral colors having a lightness greater than
90%, and the colors of the non-neutral fibers have a color difference of at least
2.0 CIELAB units, the lightness and color difference measured according to ASTM committee
E12, standard E-284, to form a yarn having a color distinctly different than either
of the colors of the two different feed fibers.
44. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
the continuous filaments in a break zone by increasing the fiber speed within the
break zone thereby creating a discontinuous filament fiber, the break zone including
drafting the fiber, and consolidating the discontinuous filaments in a consolidation
zone to form a yarn, wherein the improvement comprises:
feeding at least two different fibers into the process and combining them before breaking
in the break zone, the fiber differences being differences in strength and one of
the fibers having a strength of 10 gpd or more and the other fiber having a strength
of less than 8 gpd; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
45. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
the continuous filaments in a break zone by increasing the fiber speed within the
break zone thereby creating a discontinuous filament fiber, the break zone including
drafting the fiber, and consolidating the discontinuous filaments in a consolidation
zone to form a yarn, wherein the improvement comprises:
feeding at least two different fibers into the process and combining them before breaking
in the break zone, the fiber differences being differences in polymer composition
with one of the fibers being a fluoropolymer and the other fiber being non-fluoropolymer;
and
withdrawing the yarn from the process at a speed more than 4 times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
46. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
the continuous filaments in a break zone by increasing the fiber speed within the
break zone creating a discontinuous filament fiber, the breaking zone including drafting
the fiber, and consolidating the discontinuous filaments in a consolidation zone to
form a yarn, the fiber following a path through the process, wherein the improvement
comprises:
feeding a crimped continuous filament fiber into the process before breaking the fiber
in the break zone; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
47. The method of claim 46, wherein the crimped continuous filament fiber is selected
from the group consisting of bicomponent fibers and biconstituent fibers.
48. The method of claim 47, wherein the crimped continuous filament fiber is a bicomponent
fiber comprised of 2GT and 3GT having a component ratio between 70:30 and 30:70.
49. The process of claim 46, further comprising heating the crimped continuous filament
fiber to a temperature of at least 100 C in a heat treatment zone before breaking
the continuous filaments in the break zone.
50. The process of claim 49, further comprising drawing the crimped continuous filament
fiber by increasing the fiber speed within the heat treatment zone.
51. A process for converting continuous filament fiber into discontinuous filament yarn
comprises a plurality of functional zones at least including breaking the continuous
filaments in a break zone by increasing the fiber speed within the break zone thereby
creating a discontinuous filament fiber, the break zone including drafting the fiber,
and consolidating the discontinuous filaments in a consolidation zone to form a yarn,
wherein the improvement comprises:
feeding another continuous filament fiber into the process at or after the exit end
of the first break zone; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the converted fiber to the process, so the consolidated yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.
52. The process of claim 51, wherein the another continuous filament fiber has an elongation
to break greater than about 100% and an elastic recovery of at least 30% from an extension
of 50%.
53. The process of claim 51, wherein the another continuous filament fiber has an elongation
to break of less than 10% and a strength of greater than 10gpd.
54. The process of claim 13, wherein the crimped structures comprise partially drawn or
fully drawn bicomponent filament structures and biconstituent filament structures.
55. A process for converting continuous filament fiber into discontinuous filament yarn,
which process comprises a plurality of functional zones at least including breaking
the continuous filaments in a break zone by increasing the fiber speed within the
break zone thereby creating a discontinuous filament fiber, the break zone including
drafting the fiber, and consolidating the discontinuous filaments in a consolidation
zone to form a yarn, wherein the improvement comprises:
feeding at least two different fibers into the process and combining them before breaking
in the break zone, the fiber differences being differences in denier per filament
and one of the fibers having a denier per filament of less than 0.9 and the other
fiber having a denier per filament greater than 1.5; and
withdrawing the yarn from the process at a speed more than four times the input speed
of the fiber to the process, so the discontinuous filament yarn has been reduced to
less than 500 filaments in any cross-section of the yarn.