Background of the Invention
[0001] The present invention relates to a process for making fibrous polyolefin products
by melt spinning and products thereof.
[0002] While fibrous polyolefins, particularly polypropylene, have been found to possess
certain characteristics superior to other synthetic fibrous materials, it is generally
recognized that fibrous polyolefins have peculiarities not possessed by other synthetic
fibers, which often limit the processability of such materials and limit the end uses
to which the products can be applied. For example, the processability limitations
result in relatively low extrusion, spinning and wind-up speeds. Often high breakout
rates are experienced and further processing of the spun fibers is limited, to the
extent that inconsistent texture, broken filaments, lack of color control and difficulty
in knitting and weaving are often encountered. The products produced by melt spinning
polyolefins also have relatively high spun denier, low tenacity, low birefringence,
high elongation, high boiling water shrinkage, low modulus of elasticity, as well
as other limitations which limit the uses to which the fibrous materials can be applied.
It is also recognized that polyolefin fibers cannot generally be utilized in their
as-spun state, i.e., with little or no further processing.
[0003] It is therefore an object of the present invention to provide an improved process
for producing fibrous polyolefin products which overcomes the above-mentioned and
other disadvantages of prior art processes and improved fibrous polyolefin products
which overcome the above-mentionfd and other disadvantages of prior art products.
Another object of the present invention is to provide a process for producing melt
spun, fibrous polyolefin products and fibrous polyolefin products which can be utilized
with little or no additional processing. Another object of the present invention is
to provide an improved process for producing fibrous polyolefin products which can
be carried out at relatively high speeds, particularly higher speeds of extrusion,
spinning and wind-up. Another and further object of the present invention is to provide
an improved process for producing fibrous polyolefin products which result in products
of a low spun denier with consequent lower draw ratios and improved products thereof.
Yet another object of the present invention is to provide an improved process for
producing fibrous polyolefin products of improved processability, particularly reduced
breakout, higher draw ratios, higher and more constant twist levels during false twist
texturing, better ease of handling in knitting, weaving, etc., improved color control
and improved products thereof. A still further object of the present invention is
to provide fibrous polypropylene products having a low spun denier, high tenacity,
high birefringence, low elongation, low boiling water shrinkage, high modulus of elasticity
and/or high break strength. A still further object of the present invention is to
provide fibrous polyolefin products of improved coherency and/or bulkiness. These
and other objects of the present invention will be apparent from the following description.
Summary of the Invention
[0004] In accordance with the present invention, novel polyolefin filament products are
produced by melt spinning a polyolefin having a molecular weight distribution of less'than
about 7 (a MW/MN ratio determined by gel permeation chromatography) and a melt flow
of between about 20 and about 60 which are useful in their as-spun condition without
further processing and have high tenacity, high birefringence and low elongation.
In other aspects, the novel products can be converted to other useful products by
one or more additional processing steps, including improving the coherency and/or
bulkiness by heat setting, texturing, jet texturing such as using a Taslan jet, plying,
entangling, and cutting into staple. Still another aspect of the process includes
drawing the melt spun fibers, twist-drawing, draw-texturing, draw-twisting, draw-winding,
and/or draw-entangling.
Detailed Description
[0005] The process of the present invention comprises producing polyolefin, particularly
polypropylene, filament products by melt spinning a polypropylene having a molecular
weight distribution of less than about 7 and a melt flow between about 20 and about
60.
[0006] The term "molecular weight distribution", as utilized herein, refers to the ratio
of the weight average molecular weight to the number average molecular weight. The
term "melt flow", as utilized herein, refers to the weight in grams of the polymer
which can be extruded within a particular time under a constant dead weight load at
a given temperature as determined by ASTM-D-1238, Condition "L". The term "as-spun"
as used herein, refers to the filament products of the invention in their condition
when taken up on the first wind up package after having been melt spun. Various terms
have been used in the art to designate treatments of a plurality of collected filaments
or a yarn and a plurality of yarns to improve the coherency of the filaments and/or
improve the bulk of the yarn. A process in which the yarn or yarns are heated, twisted,
cooled and then untwisted is generally referred to as "false-twist tex'turing" or
simply "texturing". This terminology is almost universally accepted and will be utilized
as above defined in the present application. By contrast, where a yarn or yarns is
twisted but not subsequently untwisted, the universally accepted terms which will
be used herein are "true twist" or simply "twist". Some confusion exists however in
the terms used to describe other such treatments, particularly where the yarn or yarns
are subjected to a jet or jets of air under pressure. In the latter instance, the
results produced and the terminology applied depends upon the condition of treatment,
such as air pressure, the direction of the air jet relative to the path of yarn travel
and the relative tension being applied to the yarn during treatment. The term "Taslan
texturing" (Taslan is a trademark of E.I.duPont de Nemours and Company) as used herein
is meant to refer to a process and product in which a jet or jets of air are directed
against the yarn, usually in the direction of travel of the yarn, forming a turbulent
region, the speed or tension on the yarn is greater at the entrance to the jet than
at the exit (net overfeed) and the filaments of the resultant product have a multitude
of ring-like loops, coils and whorls at random intervals along their lengths. The
term "entangling" or "intermingling", sometimes called "interlacing" as used herein,
refers to a process and product in which a jet or jets of air are directed against
the yarn or yarns, usually at a 90° angle to the yarn path, the speed or tension on
the yarn is substantially the same at the entrance and exit of the intermingler and
the resultant product has a high degree of intermingling or entangling of the filaments
but is substantially free of. loops, coils and whorls. Finally, "plying" is used to
refer to a process and products in which two or more yarns are formed into a single
yarn by twisting or intermingling in a jet. The terms "cold draw" or simply "draw"
refers to a process in which filaments or yarns are drawn or stretched (with or without
heat and during or after windup) after the spun filaments have solidified as opposed
to drawing which occurs during the spinning of the filaments and before the solidification
thereof. Stretching which occurs while spinning and before the filaments have solidified
will be referred to as "melt drawing" and the products thereof as "partially oriented"
products. The term "finish" indicates a liquid composition applied to the yarn during
melt spinning that acts as a lubricant and imparts desirable characteristics to the
yarn.
[0007] In a preferred embodiment, melt spinning is carried out at a take-up speed within
the range of about 1200 to 5000 meters per minute and still more preferably between
about 1500 and 4000 meters per minute.
[0008] In another embodiment unique products are obtained by melt spinning, carried out
at take-up speeds in the range of 800-1200 meters per minute, draw-texturing at least
three of the yarns as spun with the direction of twist for two yarns being different
from the third, then plying the yarns in an interlacing jet. The product of this embodiment
is simultaneously draw-textured at a draw ratio of 4.0 to 1 to 2.0 to 1.
[0009] The products produced in accordance with the present invention have a number of advantageous
characteristics not heretofore present in melt spun polyolefins. Specifically, the
polyolefin filaments have a spun denier below about 25 per filament. In the as-spun
condition, the products have a high birefringence, usually in excess of about 0.015.
The products also have low elongations between about 100 and 350 percent as measured
by ASTM Method 2256 and preferably in the range of about 100 to 250 percent. In the
alternative, drawn filament materials can be produced having conventional spun deniers
but which are drawn at lower draw ratios. The as-spun products also have a high tenacity
above about 2.4 grams/denier and, to the extent that the filament materials are further
processed by drawing or twisting, higher cold draw ratios may be utilized. For example,
draw ratios within the range of 2.0/1 to 4.0/1 can be utilized.
[0010] While the polyolefin filament products of the present invention are useful in their
as-spun condition, these products can be further processed by a wide variety of treatments
to form the same into yarns of desired characteristics for use in a variety of textile
products, such as woven or nonwoven material, tufted products and the like. For example,
the products may be heat set and entangled. Such processes to improve the coherency
may be performed during the spinning operation (prior to winding up) or after collecting
the fibers and winding the same. Excellent products can also be produced by crimping,
such as steam crimping, or stuffer box crimping and cutting the crimped materials
into staple. The as-spun products of the present invention can also be further improved
by subjecting the same to further processing which includes cold drawing. Such processing
can involve spin-drawing, twist-drawing, false-twist texturing, draw-texturing, draw-twisting,
and draw-Taslan texturing.
[0011] The preferred polyolefin, fiber-forming materials for use in accordance with the
present invention are homopolymers of polypropylene. However, a fiber-forming resin
comprising a copolymer of propylene with a small amount (less than 15%) of an olefinic
monomer, such as ethylene, butene or a diene monomer, such as butadiene, isoprene,
etc, may be employed. If desired, a fiber-forming resin blend composed of a predominant
amount of a propylene polymer and a small amount (less than 15%) of at least one polymer
of the above mentioned olefinic or diene compound may be used. Therefore the term
"polypropylene" as used herein is intended to include the propylene homopolymers,
polymer blends and copolymers mentioned above. As for the fiber forming resin, it
is preferable to employ a crystalline polypropylene homopolymer having a molecular
weight distribution of less than about 7 and a melt flow of between about 20 and about
60.
[0012] The present invention will be more readily understood by reference to the drawings.
Brief Description of the Drawings
[0013]
FIGURE I schematically illustrates a melt-spinning process for producing an as-spun
product;
FIGURE 2 schematically illustrates an embodiment in which a yarn is twist-drawn;
FIGURE 3 schematically illustrates several techniques for improving the coherency
and/or bulking a yarn;
FIGURE 4 schematically illustrates an embodiment in which a yarn is sequentially draw-textured;
FIGURE 5 schematically illustrates an embodiment in which a yarn is simultaneously
draw-textured;
FIGURE 6, schematically illustrates in slightly greater detail a false-twist texturing
operation;
FIGURE 7 schematically illustrates a spin-draw embodiment;
FIGURE 8 schematically illustrates an embodiment in which a yarn is draw-twisted;
FIGURE 9 schematically illustrates an embodiment in which two yarns are draw-Taslan
textured;
FIGURE 10 schematically illustrates an embodiment including crimping and cutting into
staple; and
FIGURE 11 schematically illustrates an embodiment in which a plurality of yarns are
draw-textured and interlaced.
[0014] In referring to the drawings it should be recognized that the spatial relationships
of the elements are not necessarily those which would be utilized in a commercial
operation and that certain elements and items of equipment have been enlarged with
respect to other elements or items of equipment so that the character thereof can
be illustrated in somewhat greater detail.
[0015] In accordance with FIGURE 1, which illustrates one embodiment of the present invention,
a plurality of filaments are melt spun from spinneret 10. The filaments 12 then pass
through a quench zone 14 where they are cooled by blowing air therethrough. Applicator
56 applies a finish to the yarn. The filaments 12 then pass through converging guide
16 where they are collected to form a yarn 18. Converging guide 16, as will appear
hereinafter, may be a pigtail type eyelet, a slotted roller, or any conventional converging
or collecting means. The yarn 18 then passes to a conventional winder wherein traversing
guide 20 moves laterally to wind the yarn and form a package 22. The drawing that
occurs between the spinneret 10 and the take-up package 22 provides partial orientation
of the yarn. As has been pointed out previously, filaments and yarn made in accordance
with the present invention are useful for various purposes in their as-spun condition
with no subsequent processing or treatment other than that shown in FIGURE 1.
[0016] FIGURE 2 of the drawings shows another embodiment of the present invention wherein
yarn, produced in accordance with FIGURE 1, is further processed by twist-drawing.
In accordance with FIGURE 2, a yarn package 22, such as that produced in FIGURE 1
is mounted on twister 24. The yarn is drawn off package 22 and passes through pretension
gate 26, thence through the core of package 22 and through rotatable spindle 28. Rotatable
spindle 28 is attached to shaft 30 which is driven by belt 32. Twister 24 is referred
to as a "two-for-one twister" in that it inserts two turns of true twist for each
rotation of spindle 28. The twisted yarn then passes through guide elements 34 and
36. The yarn is wrapped several times about feed rolls 42 and several times about
draw rolls 46 which operate at speed greater than rolls 42 and thus draw or stretch
the yarn in the zone between the rolls. Optionally, the drawn yarn can pass over heater
44 to rolls 46 to heat the yarn during drawing, or the rolls 42 and 46 can be heated,
eliminating the need for hot plate heater 44. From draw rolls 46 the yarn passes over
stationary guide 48 and thence through traverse guide 50 of a winder, which ultimately
forms package 52. A more detailed description of the operation shown in FIGURE 2 can
be found in U.S. Patent 4,122,667.
[0017] FIGURE 3 illustrates a modification of the present invention in which one or more
treatments are given to the as-spun yarn 18 to improve the coherency and/or bulkiness
of the filaments of the yarn. These treatments include entangling the yarn and/or
heat setting the yarn. Specifically, the plurality of filaments 12 pass over ceramic
guide 54 where they are collected or converged, in the same manner as in eyelet-type
converging guide 16 of FIGURE 1, to form the yarn 18. The yarn 18 may then be passed
over applicator 56 which applies a finish to the yarn and thereby improves the coherency
of the filaments of the yarn and acts as a lubricant during processing. Finish applicator
56, as shown in the drawing, is what is known as a "kiss roll". The yarn 18 then passes
over ceramic guide 58 and thence to godet rolls 60. From godet rolls 60 the yarn passes
through a jet tyre entangler 62. Entangler 62 may be of the type shown and described
in U.S. Patent 2,783,609. In this type of entangler the filaments of the yarn are
intermingled, but have no significant coils, loops or whorls, by a high velocity air
jet. This treatment improves the coherency of the filaments of the yarn for windup.
The entangled yarn then passrs to winder 64 where it is wound on package 66. It should
be recognized at this point that the finish applicator 56 and entangler 62 may be
used alone or in combination and that either or both may be placed in any of a number
of different positions between converging guide 54 and winder 64. In an alternative
form of improving the coherency of the filaments of the yarn, the yarn package 66
may be placed in an autoclave 68 where the yarn is heat set at about 120°C. The beat-set
yarn also has improved coherency of the filaments when used alone or it may be used
in combination with the application of a finish and/or entangling.
[0018] FIGURE 4 of the drawings illustrates yet another embodiment of the present invention
wherein the yarn 18, as produced in FIGURE 1, is subjected to a subsequent treatment
involving draw-texturing. In accordance with the embodiment of FIGURE 4, the yarn
18 passes around input rolls 70 thence about hot pin 72 or across an appropriate hot
plate and finally around draw rolls 74 which are rotated at a speed greater than input
rolls 70 to thereby stretch or draw the yarn. The drawn yarn then passes over a plate-type
first stage heater 76. From heater 76 the yarn passes through a disc-type, false-twist
spindle 78. From disc-type false-twist spindle 78 the yarn passes between intermediate
rolls 80 and thence to second stage heater 82. From second stage heater 82 the yarn
passes through output rolls 84 and thence to takeup package 86 which is driven by
package drive roll 88. It should be noted that a conventional false twist spindle
could be substituted for the disc type illustrated here and in the other embodiments.
[0019] FIGURE 5 of the drawings illustrates an alternative form of the method of FIGURE
4 which is referred to in the art as simultaneous draw-texturing. It is to be observed
that the process of FIGURE 5 differs from that of FIGURE 4 only to the extent that
hot pin 72 and rolls 80 are eliminated and the yarn is heated and drawn simultaneously
with the insertion of false twist to the yarn by positioning draw rolls 74 downstream
of disc-type false-twist spindle 78.
[0020] FIGURE 6 of the drawings, although schematic in nature, shows in somewhat greater
detail the false twist texturing operation and graphically illustrates why it is referred
to as "friction" false twisting. Specifically, the yarn 18 passes over first stage
heater 76 and thence to disc-type false-twist spindle 78, illustrated as an array
of rotating friction discs that impart false twist to the yarn. In the zone containing
first stage heater 76 to disc-type false-twist spindle 78, twist is inserted and heat
set in the yarn. From the lower end of heater 76 to disc-type false twist spindle
78 a cooling zone makes up the lower or downstream portion of the twist-heat-set zone.
After passing through disc-type false twist spindle 78 and thence to intermediate
feed rolls 80, the yarn is untwisted. Since the previous treatment twisted the yarn
and heat set this twist the untwisting will not straighten the elements or filaments
but instead results in a yarn whose coherency and bulkiness are improved by the false
twisting.
[0021] FIGURE 7 of the drawings illustrates yet another embodiment of the present invention
wherein a yarn is formed by a simple spin-draw operation. In accordance with FIGURE
7 the yarn 18, formed by passage over converging guide 54, passes over feed rolls
90, thence to heater 92 and draw rolls 94, operating at a higher speed than rolls
90.
[0022] FIGURE 8 of the drawings shows yet another after-treatment to which the as-spun yarn
of FIGURE 1 can be subjected. Specifically, the operation of FIGURE 8 is what is generally
referred to as draw-twist. In accordance with FIGURE 8 the yarn 18 from package 22
passes over feed rolls 96, over heater 98 and thence over draw rolls 100. The latter,
of course, are operated at a speed higher than the speed of feed rolls 96 to thereby
stretch or draw the yarn. The drawn yarn then passes through guide 102 and thence
to rotatable flyer 104 which winds the yarn up on pirn 106. As flyer 104 rotates,
it inserts true twist in the yarn. It should be recognized at this point that a spin-drawn
yarn, prepared in accordance with FIGURE 7, or a draw-twisted yarn prepared in accordance
with FIGURE 8 may thereafter be subjected to a false twist-texturing operation, as
performed in the double heater, false-twist texturing machines illustrated in FIGURES
5 and 6 of the drawings.
[0023] FIGURE 9 illustrates an after treatment of the as-spun yarn produced in FIGURE 1
wherein the yarn 18 is draw-Taslan textured as an effect yarn and combined with a
core yarn 19. In accordance with FIGURE 9 the yarn 18 from package 22 is passed through
a draw zone comprising feed rolls 108, heater 110 and draw rolls 112 and feed rolls
113. From the draw zone the yarn 18 is passed to a Taslan jet 114. Core yarn 19 from
package 23 is passed by feed rolls 115 operating at a slower speed than rolls 113
to Taslan jet 114. As previously indicated, the yarns in passing through Taslan jet
114 are subjected to turbulence in a high velocity air stream and separated from the
air stream by being jetted against baffle 116 and then turned in a generally perpendicular
path. Due to the overfeed of yarn 18, it becomes the effect yarn. Passage through
the jet 114 results in the filaments of the yarn forming loops, rings and whorls therein
and effecting some intermingling of the filaments. Generally, the yarns are under
tension as they enter Taslan jet 114 and as the core and effect yarn 119 exits Taslan
jet 114 it is traveling at a reduced speed and this reduction in tension during the
turbulence contributes to the formation of the loops, etc. The yarn 119 then passes
through guide 118 to takeup rolls 120, thence through traverse guide 122 of a winder
and onto a package 124. Taslan jet 114 is of the type well known in the art and will
not be further described herein.
[0024] The embodiment of the present invention shown in FIGURE 10 subjects the yarn 18,
produced in accordance with FIGURE 1, to a subsequent treatment involving crimping
of the yarn and, optionally, cutting the crimped yarn into staple. Specifically, the
yarn 18 is fed to crimper 126 which comprises feed rolls 128 and stuffer box 130.
The specific crimper shown is a steam crimper and a preferred steam crimper is shown
and described in U.S. Patent 3,911,539. From the stuffer box 130 the crimped yarn
passes to J-box 132, over tensioning rolls 134 and thence to staple cutter 136. Staple
cutter 136 cuts the crimped yarn into short fibers or staple which are then passed
to bailer 138. At this point it should be recognized that additional finish may be
applied to the yarn prior to passage through crimper 126 and the yarn may be cold
drawn prior to the crimping operation.
[0025] FIGURE 11 of the drawings illustrates a novel technique for forming a plied and interlaced
yarn from a plurality of draw-textured yarns produced in accordance with the draw-texturing
operations illustrated in FIGURES 4, 5, and 6. Preferably, a plurality of yarns are
simultaneously draw-textured as illustrated in FIGURE 5. Specifically, three separate
yarns 18A, 18B and 18C, respectively, are simultaneously draw-textured by passing
the same through disc-type false-twist spindles 78A, 78B and 78C, draw rolls 74A,
74B and 74C, second stage heaters 82A, 82B and 82C and output rolls 84A, 84B and 84C.
4,'hile the draw-texturing devices are shown as offset in FIGURE 11, for clarity of
illustration only, it is to be understood that units A, B and C would be in side-by-side
relationship in actual operation. The draw-textured yarns 18A, 18B and 18C are thereafter
passed through an entangling or interlacing device 140 which plies the yarns together.
The interlacer 140 is the same type entangler or interlacer as 62, referred to in
the description of FIGURE 3 for a single yarn. Interlacer 140 generally comprises
a tube through which a plurality of yarns are fed. The tube through which the yarns
pass is provided with air from an annular plenum zone supplied with air by means of
air supply 142. To aid in stringup of the yarns in interlacer 140, the interlacer
is provided with a slot 144, which is preferably at an angle so as to aid in retention
of the yarns in the yarn tube. The interlaced yarn then is wound up on takeup package
146 driven by package drive roll 148. It has been found in accordance with the present
invention that the system of FIGURE 11 is particularly useful in the production of
a heather-type yarn, in which three different colors of yarn are plied by interlacing.
Specifically, it has been found, in accordance with the present invention, that, in
a system such as that of FIGURE 11, if a plurality of yarns to be interlaced are all
twisted in the same direction this results in a high torque being applied to the yarns.
However, it was discovered that if alternate ones of the plurality of yarns were false
twisted in the opposite direction, this undue torque was essentially eliminated and
a heather-type yarn of substantially improved characteristics was produced. This is
illustrated in FIGURE 11 by the rotational direction arrows applied to false-twist
spindles 78A, 78B and 78C. In this particular illustration, where three yarns are
interlaced, the middle yarn or 18B would be false twisted in the opposite direction
to yarns 18A and 18C. It should be recognized however that more than three yarns could
be interlaced, in fact as many as eight could be interlaced. where more than three
yarns are interlaced, as previously indicated, alternate false-twist spindles would
be operated in a reverse direction.
[0026] The following examples illustrate the nature and advantages of the present invention.
EXAMPI,E I
[0027] A comparison was made of the as-spun properties of a conventional melt spun polypropylene
having a broad Molecular Weight Distribution
= 12.1 and a low resin Melt Flow = 10-12 (Resin A); two polypropylenes having a broad
Molecular Weight Distribution
= 12 and a high resin Melt Flow = 30 and 44, (Resins E and K, respectively), a polypropylene
having a broad Molecular Weight Distribution = 12 and a low resin Melt Flow
= 3 (resin L) and a plurality of different resins having narrow Molecular Weight Distributions
(4.2 to 7.5) and high resin Melt Flows (21 to 57). The letter designations in Table
I indicate the individual resins utilized. Runs 1 to 12, 19, 20, 22 and 25 utilized
a 12x48 mil spinnerette with 325 mesh screen. Runs 1 to 12 utilized a spin temperature
of 293°C and runs 19, 20, 22 and 25 a spin temperature of 246°C. Since some difficulties
in spinning and quenching were encountered and it appeared desirable to spin resin
B at lower spin speeds for comparison runs 13 through 18, 21, 23, 24 and 26 were spun
at 254°C spin temperature through a 32-hole - 0.012x0.048 inch spinnerette and utilizing
quench air at 80 ft/min. Some difficulties were again experienced at spin speeds above
2400 meters/minute and runs 36 through 43 were spun through a spinnerette with 0.03x0.090
inch holes. Runs 44 through 57 were spun, utilizing a spinnerette having 0.012x0.048
inch holes at a spin temperature of 312°C. Runs 27 through 35 were run at a spin temperature
of 250°C, a nominal godet speed (spin speed of 2500 meters/minute) and utilizing quench
air at 80 ft/min. A finish herein designated finish C as in Table V was applied to
the collected filaments at a rate of 1% by weight and comprised 86.63% Nopcolube 2152P
(Diamond Shamrock, Morristown, N.Y.), 13.32% ethoxylated cetyl/stearyl alcohol (25
moles ethylene oxide per molecule) and 0.05% of Givgard DXN (sold by Givaudin Corp.
of Clifton, N.J.) an antimicrobial preservation agent. It is to be noted that the
melt flow listed in Table I is "melt spun melt flow" or the melt flow as measured
after melt spinning. Generally, the resin melt flow of relatively low resin melt flow
polymers will differ significantly from the melt spun melt flow but with relatively
high resin melt flow polymers the melt spun melt flow will not change appreciably.
Table 1
[0028] Observation of the results set forth in Table 1 show that the narrow Molecular Weight
Distribution - high Melt Flow resins exhibited a number of improved properties, including
low elongation, high birefringence, high tenacity and low spun denier, particularly
at high spin speeds above about 1500 meters/minutes. From the properties shown it
is clear that the narrow Molecular Weight Distribution - high Melt Flow products of
the present invention can be utilized for numerous commercial purposes in their as-spun
condition without further treatment or little additional treatment.
[0029] Since the largest volumes of samples at the full range of spin speeds and the as-spun
physical properties of yarns produced from Resin L approached those of the preferred
narrow Molecular Weight Distribution - high Melt flow resins, samples of yarns produced
in runs 44 through 57 were cold drawn without twisting to determine whether further
treatment would be beneficial. In these tests, the yarns were drawn at a speed of
314 meters/min. , with 7 and 6-1/2 wraps about the feed rolls and the draw rolls,
respectively, and with temperatures of 80 and 125°C on the feed rolls and draw rolls,
respectively.
[0030] The physical properties of the drawn yarns are set forth in Table 11 below.
It is to be observed that improvement in praycrtirs required cold drawing at high
draw ratios.
[0031] Polymer B was melt spun using a 70 hole 0.020 x 0.020 inch hole spinnerette and a
360 mesh screen in an effort to make yarn having a total denier of 300. Quench air
was 80 ft/min. A finish C was applied to the yarn at a rate of 1% by weight and comprised
86.63% Nopcolube 2152P (Diamond Shamrock, Morristown, N.J.) 13.32% Ethoxylated cetyl/stearyl
alcohol (25 moles ethylcne oxide per molecule) and 0.05% Givgard DXN. The yarns were
also heat set for 5 hours at the temperature indicated. These runs and the physical
properties of the yarn are set forth in Table III below.
[0032] Run 63 is rather heaningless since the supply of polymer began to run out at the
end of the run. Also problems of lost filaments occurred in the spinning at 3500 m/min.
However, the data clenly indicates that heat setting does reduce the elongation and
shrinkage significantly. In spite of the spinning problems at 3500 m/min. it can also
be seen that the higher speed (3500 m/min.) produces a yarn of higher tenacity and
lower elongation than spinning at the lower speed (2500 m/min.).
[0033] In order to determine what effect false-twist draw-texturing during spinning would
have on products of the present invention, three polypropylenes were run under varying
conditions of draw ratio and twist ratios to produce 600, 700, 800 and 900 denier
yarns from each polymer. In these runs the polymers were each run on a 34 hole, 0.012x0.048
inch hole spinnerette with a 325 mesh screen. A polymer pressure of 2000 psig, a spinning
speed of 800 m/min. and a quench air rate of 80 ft/min. were utilized in all runs.
Polymer temperatures (°C) at each of four extruder zones and the polymer properties
were as follows:
0.5% by weight of a finish, herein designated finish B as in Table V, comprising a
10% emulsion of a reactive polysiloxane (Dow Corning 1111 Emulsion, sold by Dow Corning
Corp.) was applied to the yarns.
[0034] A Scragg, 12 ceramic disc friction texturing machine was utilized, with temperatures
of 150°C at both the first and second heaters. Twist and contraction factor were measured
on snatched samples. Overfeed was 12% to the setting zone. Denier was calculated at
the draw roll using the formula:
Undrawn Denier Draw Ratio
[0035] The speed of the draw roll was 297 m/min. at D/Y 1.56 and 272 m/min. at D/Y 1.71.
[0036] Table IV below sets forth the results of these runs.
[0037] Symbols above represent the following:
DR = Draw ratio
D/Y = Surface speed of discs/linear speed of yarn
SD = Spun Denier
t1 = tension in grams as measured above false twist spindle
- t2 = tension in grams as measured below false twist spindle FD = Denier at draw roll
- Undrawn Denier/Draw Ratio
CF = Contraction Factor - untwisted length/twisted length tpi = turns per inch
600 spun denier yarn of polymer N had broken filaments at a draw ratio of 2.622 and
D/Y of 1.56 and would not run at higher draw ratios and D/Y's.
[0038] It was concluded during the above runs and from an analysis of the data, increased
D/Y decreases t
2 but has little effect on twist, the low melt flow polymer did not run well under
any conditions as compared with the high melt flow polymers and tpi is a function
of denier and is little affected by draw ratios, D/Y and tension.
[0039] Based on the good performance attained in the previous tests, polymer M was false-twist,
draw-textured in a variety of colors to produce 250 denier through the 34-hole spinnerette.
All samples were spun at 800 as-shun denier and at 800 m/minute. Draw-texturing conditions
were at a draw ratio of 3.413, D/Y of 1.71, 272 m/min. heater temperatures of 150°C
and an overfeed across the second heater (to setting zone) of 12%. Two different finishes,
namely, the previously described finishes B and C, were applied in some runs.
[0040] Table V lists the as-spun properties.
[0041] The properties of the finished yarns after draw-texturing are set forth in Table
VI.
syarn proke out
[0042] All samples in the above test spun without incident. However, the yarns to which
finish B was applied fused during texturing and the yarn of run 113 broke out. in
attempting to snatch.
[0043] In order to prepare 3-ply yarns the spinning and false-twist draw-texturing of the
previous runs were repeated except for those instances where finish B had been utilized.
Operation of an entangler of the type referred to in FIGURE 3 was tried but found
to produce too much entanglement. Thereafter, an interlacer of the type specifically
referred to in the discussion of FIGURE
11 was used with each position of the disc type false-twisters all rotating in the same
direction but the composite yarn produced was of high torque. Finally, the last mentioned
interlacer was used with the false-twist positions alternating direction of twist
and the air to the interlacer or entangling jet at 30 pai. Two composite yarns of
three yarns cach in accordance with the method described with reference to FIGURE
11. This procedure eliminated the excess torque and produced acceptable composite
yarns.
[0044] Table VII sets forth the properties of the individual yarns and the two composite
yarns.
[0045] It was determined from the above data that the entangling procedure utilized herein
(entangling during spinning and prior to windup) also increased the denier above what
would theoretically be expected by a conventional entangling procedure (entangling
individual yarns after windup). It should be recognized that as many as 6 to 8 yarns
could be similarly interlaced to produce composite yarns of 1500 to 2000 denier.
[0046] The composite yarns were also knit and woven into fabrics without difficulty. The
knit sample was boiled off and developed good bulk and pleasing hand. The composite
yarns conld be used in hand knit items, upholstery fabrics, etc.
[0047] This test was carried out to evaluate the Taslan texturing of yarns produced in accordance
with the present invention which have been twisted but not drawn. Polymer B was spun
at 2500 n/min. and in the same manner and under the same conditions as the previous
example except that it was wound at 40 grams tension. The yarn was twisted on a Single
Spindle Dienes Twister at 465 m/min., and 5500 rpm spindle speed to produce 0.3 twist
level. The properties of the untwisted and twisted yarns are set forth in Table VIII
below.
[0048]
[0049] This yarn, a twist-drawn yarn from polymer A and a core yarn irom polymer A were
Taslan textured at a core feed rate of 187 m/min., an effective feed rate of 337 m/min.
and a take-up speed of 182 m/min. The yarn was also run side-by-side with a commercial
yarn with the speed being the maximum to get acceptable bonding with the core in the
commercial yarn. Inspection of the yarns indicated that the yarn of the present invention
tangled with the core yarn better than the commercial yarn.
[0050] In order to evaluate draw-Taslan Lexturing of the yarns of the present invention
a series of runs were made comparing yarns prepared from Polymer C and from Polymer
N at different spin speeds and in different colors. A 34-hole, round, 0.015 x 0.019
inch spinnerette was used. Spinning temperatures (°C) were 250°C for polymer C and
292°C for polymer N.
[0051] The quench air rate was
<80 ft/min. and 1.1% by weight of linish B was applied. Table IX below sets forth the
as-spun dcniers obtained.
[0052] Samples of Polymer C spun well at all speeds but difficulties were encountered in.
quenching Polymer N at 1500 and 2200 m/min. due to the presence of wild filaments.
BAD ORIGINAI
[0054] It is clear, from the results set forth in Table X that the drawing efficiency (lack
of broken filaments, etc.) is much better for the narrow molecular weight distribution
Polymer C than for the broad molecular weight distribution (conventional) Polymer
N, both with the heated plate and with no beating. The actual draw was also higher
for Polymer C than for Polymer N and increased as draw tension decreased. The color
data shows a greater color effect on Polymer N, when it is cold drawn, than on Polymer
C. The hot plate and lower draw tensions appear to improve the color differences of
Polymer C samples. The unusual result (low WE) observed in run 142 when the sample
of Polymer N spun at 2200 m/min. was cold drawn resulted from the sample continuing
to shrink after windup. In general, the low WL values with cold draw indicate that
light color results, but this can be remedied by color adjustments. Analysis of the
above runs lead to the conclusion that Polymer C can be cold drawn (with a hot plate)
during spinning at 1400 to 1800 m/min. and at full extruder output (380#/hr) with
only minimal color adjustment.
[0055] While specific examples and items of equipment have been set forth herein, it is
to be understood that such recitations are illustrative only and are not to be limiting.
1. A process for making iilament yarn; comprising, melt-spinning a polypropylene having
a molecular weight distribution of less than about 7 and a resin melt flow between
about 20 and about 60, applying a finish, and taking up the filament yarn at a speed
above about 1200 meters per minute.
2. A process in accordance with claim 1 wherein the filaments are interlaced before
takeup.
3. A process according to claim 2 wherein the filaments are additionally twist-drawn.
4. A process according to claim 2 wherein the filaments are additionally heat set.
5. A process according to claim 2 wherein the filaments are additionally sequentially
draw-textured by false twisting.
6. A process according to claim 2 wherein the filaments are additionally simultaneously
draw-textured.
7. A process according to claim 2 wherein the filaments are additionally draw-twisted.
8. A process according to claim 2 wherein the filaments are additionally draw-Taslan
textured.
9. A process according to claim 2 wherein the filaments are additionally stuffer box
crimped and cut into staple fibers.
10. A process for making filament yarn; comprising, melt-spinning a polypropylene
having a molecular weight distribution of less than about 7 and a resin melt flow
between about 20 and about 60, applying a finish, and taking up the filament yarn
at a speed between about 800 and about 1200 meters per minute. -
11. A process according to claim 10 wherein a plurality of the yarns are simultaneously
draw-textured by false twisting while reversing the direction of twist of alternate
yarns and thereafter the said yarns are plied in an interlacing jet.
12. A process according to claim 11 wherein the plurality of yarns are simultaneously
draw-textured at a draw ratio between about 2 to 1 and about 4 to 1.
13. A polypropylene filament yarn product melt spun from a polypropylene having a
molecular weight distribution of less than about 7 and a melt flow between about 20
and about 60, said filaments having a birefringence above about 0.15, a tenacity above
about 2.4 grams per denier, an elongation between about 100 and about 350 percent,
and a denier per filament of less than about 25.
14. A polypropylene filament yarn produced according to a process of one of claims
1 to 12.