FIELD OF INVENTION
[0001] This invention concerns improved drawing of polyester filaments, and more particularly
a process for drawing mixed polyester filaments in the same bundle, especially drawing
a tow of such mixed filaments, and the resulting drawn filaments and bundles and downstream
processes therefor and products thereof.
BACKGROUND OF INVENTION
[0002] Polyesters have been produced commercially on a large scale for processing into shaped
articles such as fibers, primarily from poly(ethylene terephthalate). Synthetic polyester
yarns have been known and used commercially for several decades, having been first
suggested by W. H. Carothers, U.S. Patent No. 2,071,251, and then Whinfield and Dickson
suggested poly(ethylene terephthalate) in U.S. Patent No. 2,465,319.
[0003] Although many polyester polymers (including copolymers) have been suggested, the
polyester most widely manufactured and used hitherto for textile fibers has been poly(ethylene
terephthalate), which is often referred to as homopolymer PET. Homopolymer PET has
generally been preferred over copolymers because of its lower cost, and also because
its properties have been entirely adequate, or even preferred, for most end-uses.
It is known, however, that homopolymer PET requires special dyeing conditions (high
temperature requiring super-atmospheric pressure) not required for nylon fibers, for
example, so copolyesters have been suggested and used commercially for some purposes.
Homopolymer PET is often referred to as 2G-T, while poly(trimethylene terephthalate)
is referred to as 3G-T (although some have started calling this PTT), and poly(tetramethylene
terephthalate) is referred to as 4G-T, and so on. Some interest has been shown in
3G-T, and also in 4G-T, but 2G-T is the polyester polymer that has so far been used
the most, so is discussed mostly hereinafter, but it will be understood that the invention
is expected to apply also to other polyesters, for instance other C
2-C
4 alkylene terephthalates, such as 3G-T and 4G-T mentioned above, and copolyesters.
[0004] Polyester fibers are either (1) continuous filaments or (2) fibers that are discontinuous,
which latter are often referred to as staple fiber or cut fibers, and are made by
first being formed by extrusion into continuous polyester filaments, which are processed
in the form of a tow of continuous polyester filaments before being converted into
staple. An important stage in the processing of such continuous polyester filaments
has been "drawing" to increase the orientation of the long chain polyester molecules,
and thereby improve the properties of the filaments. The present invention relates
to improvements in this drawing stage and to the improved products resulting therefrom.
[0005] Mostly, the objective of synthetic fiber producers has been to replicate advantageous
properties of natural fibers, the most common of which have been cotton and wool fibers.
[0006] Most of the polyester cut fiber has been of round cross-section and has been blended
with cotton. Recently, however, U.S. Patents Nos. 5,591,523 (DP-6255) and 5,626,961
(DP-6365-A) and copending application No. 08/662,804 (DP-6400) filed June 12, 1996,
and now allowed, corresponding respectively to WO 97/02372, WO 97/02373 and WO 97/02374,
the disclosures of which are hereby incorporated herein by reference, have disclosed
inventions relating to polyester tows that are suitable for conversion to slivers
on a worsted or woolen system and downstream processing on such systems, eventually
into fabrics and garments. The present invention has been made in the course of that
work, so is described with particular reference to its value in drawing polyester
filaments in tows for further processing in such systems, but is not confined to drawing
such tows and is believed to have potential for use more broadly when drawing other
bundles of polyester filaments.
[0007] As, for example, has been disclosed in U.S. Patent No. 5,591,523 (DP-6255), filaments
of different denier per filament (dpf) have sometimes been desired, so surprise was
expressed in Example 1 of that patent that is was possible to spin undrawn polyester
filaments that had been spun of significantly different denier on the same spinning
machine without adjusting the natural draw ratio and then subsequently to draw an
intimate mixture of these spun filaments simultaneously in the same tow at the same
draw ratio to provide filaments with excellent properties that were different because
of their differing dpfs (col. 6, lines 15-29). The present invention expands on this
surprising finding and extends it to the drawing simultaneously of other mixed filament
bundles beyond the mixed filament tows specified in that patent.
SUMMARY OF THE INVENTION
[0008] According to one aspect of the invention, there is provided a process of simultaneously
drawing a mixture of polyester filaments in the same bundle of polyester filaments,
wherein said mixture is a mixture of filaments of different cross-sections, the mixture
including polyester filaments having cross-sections selected from at least two of
the following types of cross-sections: scalloped-oval; trilobal; ribbon-shaped; solid;
hollow; multi-void; and round, and wherein said polyester is chain-branched with 0.1
to 0.8 mole % of chain-brancher. The mole % is calculated conventionally as the molecular
weight of the chain-brancher unit divided by the molecular weight of the polymer repeat
unit times 100, the repeat unit for 2G-T being ethylene terephthalate by way of example.
[0009] According to another aspect of the invention, there is provided a mixture of polyester
filaments, wherein said mixture is a mixture of filaments of different cross-sections,
the mixture including polyester filaments having cross-sections selected from at least
two of the following types of cross-sections: scalloped-oval; trilobal; ribbon-shaped;
solid; hollow; multi-void; and round, and wherein said polyester is chain-branched
with 0.1 to 0.8 mole % of chain-brancher, and wherein the boil-off shrinkage is 0.5
to 3%. Such mixtures may be in the form of continuous filamentary drawn tows and drawn
yarns, and downstream products of mixtures of polyester filaments resulting therefrom,
including mixtures of staple (cut) fiber in various forms, including yarns, and fabrics
and garments as well as the yarns themselves, and it will be understood that the resulting
mixtures of polyester fibers may also be mixed with other fibers, such as of other
synthetic polymers, including polyamides (nylons of various types) and polyolefins,
for example, and/or natural fibers, such as cotton and wool.
[0010] According to another aspect of the invention, there is provided a mixture of polyester
filaments, obtainable by simultaneously drawing a mixture of polyester filaments in
the same bundle of polyester filaments, wherein said mixture is a mixture of filaments
of different cross-sections, the mixture including polyester filaments having cross-sections
selected from at least two of the following types of cross-sections: scalloped-oval;
trilobal; ribbon-shaped; solid; hollow; multi-void; and round, and wherein said polyester
is chain-branched with 0.1 to 0.8 mole % of chain-brancher, and wherein the boil-off
shrinkage is 0.5 to 3%.
[0011] The terms "filament" and "fiber" are used inclusively herein, and are not generally
intended to be mutually exclusive; sometimes, however, these general terms are modified,
as in terms such as "continuous filament" and "staple fiber".
[0012] Significantly, as will be explained in relation to the stress-strain curves in the
Examples, no natural draw ratio has been found when drawing simultaneously according
to the invention. Also, no neck drawing has been experienced in contrast to our experience
when drawing filaments of homopolymer 2G-T.
BRIEF DESCRIPTION OF DRAWINGS
[0013]
Figure 1 is a magnified photograph of mixed filament cross-sections according to the
invention as explained hereinafter in greater detail.
Figures 2 to 6 are average stress-strain curves of single filaments for use in mixtures
according to the invention, as described more specifically hereinafter.
DETAILED DESCRIPTION
[0014] It would be redundant to repeat what has already been disclosed in the art. As has
been indicated, the preparation of polyester polymers and spinning of filaments therefrom
has been disclosed in the art. The drawing of polyester filaments has also been disclosed
in many references dating back to those by Marshall and Thompson in Nature, Vol. 171
(January 3, 1953), pages 38-39, "
Drawing Synthetic Fibers", in J. Applied Chem., 4 (April 1954), pages 145-153 "
The Drawing of Terylene", and in Proc. Roy. Soc. (London), Vol. A221, pages 541-557, "
The Cold Drawing of High Polymers". As indicated hereinbefore, the present invention was made during work on drawing
polyester filaments in tows that were being developed for worsted and woollen processing,
so much of the detailed description herein relates to such filaments and tows, but
the inventive concept has wider application.
[0015] As indicated, the essence of the invention is the use of chain-branched polyester
polymer to make the polyester filaments that are drawn according to the process of
the invention to provide the mixtures of filaments according to the invention. The
use of chain-branchers (i.e., multi-functional, polyester-forming intermediates having
more than the requisite two functional groups that are required for polymerization,
such as a glycol and a dibasic acid, both of which are difunctional) has been disclosed
in art such as MacLean et al, U.S. Patent Nos. 4,092,299 and 4,113,704, Mead et al
in U.S. Patent No. 3,335,211, Oxford et al WO 92/13,120, Duncan, U.S. SIR H1275, DuPont
(Broaddus et al) EPA2 294,912, Reese, U.S. Patent Nos. 4,833,032, 4,966,740 and 5,034,174,
Goodley et al in U.S. Patent No. 4,945,151, and art referred to and cited therein,
such as Vaginay, U.S. Patent No. 3,576,773. Some of these references used different
terminology, such as viscosity builders, because the materials were added to enhance
spinning performance, or for other reasons. Much of this prior art related to high-speed
spinning of continuous filament yarns as feed yarns for draw-texturing, so those continuous
filaments were spin-oriented, rather than amorphous, such as are more suited for drawing
in tow form for conversion into cut fiber, which is of special interest and preference
according to the present invention. The low shrinkage of the mixtures of filaments
according to the invention distinguishes our drawn filaments from the filaments of
higher shrinkage made by high speed spinning to make spin-oriented filaments for use
as feed yarns for draw-texturing, often referred to as POY. The shrinkage is the boil
off shrinkage that is referred to at the bottom of col 6 of Knox U.S. Patent No. 4,156,071,
and is measured in the manner described there by Knox.
[0016] As indicated, U.S. Patent No. 5,591,523 and WO 97/02372 have already disclosed in
Example I the simultaneous drawing of a tow of polyester filaments of mixed dpf and
that it was surprising that this could be accomplished to give drawn filaments that
were satisfactory and with no dark dye defects. Such a process and the resulting drawn
filaments of mixed dpf, all of scalloped-oval cross-section, have already been disclosed
therein. In addition, U.S. Patent No. 5,629,961 and WO 97/02373 have disclosed filaments
of improved scalloped-oval cross-section with 6 grooves, and have incorporated the
disclosure of U.S. Patent No. 5,591,523, as did WO 97/02374 and allowed U.S. application
No. 08/662,804. It follows that the present application is particularly concerned
with additional aspects of the concept of the invention that are not already covered
in these previous patents and patent applications. Such additional aspects are now
mentioned; namely, mixtures of filaments of differing cross-sections that are not
entirely of scalloped-oval cross-section, such as one cross-section being round while
the other cross-section is non-round, for instance trilobal, ribbon-shaped or even
scalloped-oval; mixtures of more than one non-round different cross-section, such
as any mixture of such non-round cross-sections; mixtures of solid filaments and of
filaments with one or more longitudinal voids, one void being often referred to as
a hollow filament, but also multi-void filaments with, e.g., 3 or 4 voids, or with
7 voids, as disclosed, e.g., in U.S. Patents Nos. 3,745,061, 3,772,137 and 5,104,725,
and art referred to and cited therein; so far as terminology herein is concerned,
such filaments with longitudinal voids are embraced herein technically within the
concept of "non-round" filaments since their previous behavior during drawing (when
made of 2G-T homopolymer without chain-brancher) has differed from the behavior of
round (solid) filaments (made similarly without chain-brancher); also mixtures of
filaments of dpfs that differ, even when of the same cross-section (other than all
being scalloped-oval cross-section as mentioned hereinbefore), but also of different
cross-section and of different dpf; such dpf differences may be such that a higher
dpf is at least 1.1X a lower dpf, or larger differences, such as at least 1.2X, 1.3X
or 1.5X or more.
[0017] As will be seen in the Examples hereinafter, it is difficult to predict the dpfs
and properties of the drawn filaments that are obtained by drawing mixtures of filaments
according to the invention.
[0018] The invention is further illustrated in the following Examples, which, for convenience,
refer to processing on the worsted system, as explained hereinabove. All parts and
percentages are by weight unless otherwise indicated. The boil off shrinkages of the
products for all the Examples were in the range of 1% to 1.5%.
[0019] Most test procedures are well-known and/or described in the art. For avoidance of
doubt, the following explanation of procedures that were used are given in the following
paragraphs.
[0020] Instron. The average stress-strain curves were obtained as follows as an average of 10 individual
filaments of each type taken from the tow bundle. Ten samples of each type of filament
were separated from the tow bundle using a magnifying glass (LUXO Illuminated Magnifier).
The denier per filament (DPF) of each sample filament was measured on a VIBROSCOPE
(HP Model 201C Audio Oscillator). The sample filaments were mounted one at a time
on an INSTRON (Model 1122 or 1123) and the stress-strain behavior was measured. Ten
breaks were recorded for each filament type, and the average of the 10 samples was
recorded for each filament type so, as will readily be understood, values read from
a stress-strain curve of an individual filament do not necessarily correlate with
tensile properties calculated and listed as an average in the Tables.
[0021] Units - Measurements were made using conventional U.S. textile units, including denier,
which is a metric unit. To meet prescriptive practices elsewhere, dtex and CPcm equivalents
of the DPF and CPI measurements are given in parentheses after the actual measurements.
For the tensile measurements (MOD, for initial modules, and TEN, for tenacity), however,
the actual measurements in gpd have been converted into g/dtex and these latter have
been given in the Tables, whereas the stress-strain curves in the Figures show original
metric tensile values on the Y-axis.
[0022] Crimp Frequency was measured as the number of crimps per inch (CPI) after the crimping of the tow.
The crimp is exhibited by numerous peaks and valleys in the fiber. Ten filaments are
removed from the tow bundle at random and positioned (one at a time) in a relaxed
state in clamps of a fiber-length measuring device. The clamps are manually operated
and initially moved close enough together to prevent stretching of the fiber while
placing it in the clamp. One end of a fiber is placed in the left clamp and the other
end in the right clamp of the measuring device. The left clamp is rotated to remove
any twist in the fiber. The right clamp support is moved slowly and gently to the
right (extending the fiber) until all the slack has been removed from the fiber but
without removing any crimp. Using a lighted magnifier, the number of peaks on top
and bottom side of the fiber are counted. The right clamp support is then moved slowly
and gently to the right until all the crimp has just disappeared. Care is taken not
to stretch the fiber. This length of the fiber is recorded. The crimp frequency for
each filament is calculated as:
[0023] The average of the 10 measurements of all 10 fibers is recorded for the CPI (crimps
per inch), the metric equivalent being CPcm.
[0024] CTU (Crimp Take Up) was also measured on tow and is a measure of the length of the tow extended, so as
to remove the crimp, divided by the unextended length (i.e., as crimped), expressed
as a percentage, as described in Anderson et al, U.S. Patent No. 5,219,582.
[0025] Values for
non-round fiber cross sections were obtained using the following procedure. A fiber specimen is mounted in a Hardy
microtome (Hardy, U.S. Department of Agriculture circa 378, 1933) and divided into
thin sections according to methods essentially as disclosed in "Fiber Microscopy Its
Technique and Applications" by J. L. Sloves (van Nostrand Co., Inc., New York 1958,
No. 180-182). Thin sections are then mounted on a super FIBERQUANT video microscope
system stage (Vashaw Scientific Co., 3597 Parkway Lane, Suite 100, Norcross, Georgia
30092) and displayed on the Super FIBERQUANT CRT under magnifications as needed. The
image of an individual thin section of one fiber is selected and critical fiber dimensions
measured. The ratios are then calculated. This process is repeated for each filament
in the field of view to generate a statistically significant sample set, and the averages
are given herein. Aspect Ratios or Modification Ratios for the non-round cross-sections
are given in the Tables in parentheses after indication of the type of cross-section,
e.g., "SO (1.37)" indicates a scalloped-oval cross-section of Aspect Ratio 1.37. Similarly
void contents are given in parentheses after indication of a hollow cross-section,
e.g., a void content of 7% is shown as "Hollow (7%)", being measured as described
by Aneja et al. in U.S. Patent No. 5,532,060.
[0026] Relative Viscosity (LRV) is the viscosity of polymer dissolved in HFIP solvent (hexafluoro-isopropanol) containing
100 ppm of 98% reagent grade sulfuric acid. The viscosity measuring apparatus is a
capillary viscometer obtainable from a number of commercial vendors (Design Scientific,
Cannon, etc.). The relative viscosity in centistokes is measured on a 4.75 wt. % solution
of polymer in the solvent at 25°C. The H
2SO
4 used for measuring LRV destroys cross-links, specifically silicon in the case of
tetraethyl ortho silicate chain-brancher.
[0027] Non-Acid Relative Viscosity (NRV) is the viscosity of polymer similarly dissolved, measured and compared in hexafluoro-isopropanol
solvent but without any sulfuric acid. Since the acid is not present, the cross-links
are left intact when the NRV is measured.
[0028] Delta RV (ΔRV) is the expression we have used herein to define the difference between the NRV and
the LRV measured as described above, and express the amount of cross-linking destroyed
by the acid when measuring LRV.
[0029] Product Defects are classified herein in three categories:
1) Equivalent Fabric Defects (EFD),
2) Dark Dye Defects (DDD),
3) Splinters (SPL).
[0030] The first two defects (EFD and DDD) are fibers and clumps of fibers that dye darker
than normal fibers. DDDs have a diameter less than 4X the normal (drawn) fiber diameter.
EFDs have a diameter 4X the normal fiber diameter or greater. Both defects must be
longer than 0.25 inch (6.35 mm). Samples are processed through a roller top type card.
The sliver is dyed light blue and examined visually under a lighted magnifying glass.
Fibers that dye darker than the bulk of the sample are removed, classified as EFDs
or DDDs and counted. Each type of defect is reported as number of defects per 0.1
pounds (0.045 Kg) sliver. Splinters are oversized fibers or clumps of fibers. To be
classified as a splinter, this defect must also be longer than 0.25 inch (6.35 mm)
but its total diameter must be greater than 0.0025 inch (0.0635 mm).
Splinters are concentrated in the flat strip waste when a staple sample is processed
through a flat card. The flat strip waste is visually examined against a black background.
Splinters are removed, classified by size, counted, and expressed on a weight of sample
basis.
EXAMPLE 1
[0031] Mixed filaments were melt spun at 282°C from chain-branched ethylene terephthalate
polymer, such mixed filaments being a mixture of light filaments (finer denier) of
scalloped-oval (SO) cross-section and of heavy filaments (heavier denier) of round
cross-section. The different filaments were melt-spun simultaneously through different
capillaries in the same spinneret, each containing 1000 capillaries, from polymer
containing 0.24% (0.22 mole %) tetraethyl silicate (TES, essentially as described
in Mead et al., U.S. Patent No. 3,335,211) and having 10.2 LRV and 15.3 NRV (so 5.1
ΔRV), at a total of 23.68 rate lbs/hr (10.75 Kg/hr) for each spinneret, and wound
on bobbins at 1800 ypm (1650 m/min). The spinnerets had 516 round capillaries, each
of flow area 0.0003079 sq. in. (0.199 mm
2) to make heavy filaments (round cross-section), and 484 non-round capillaries each
of flow area 0.0002224 sq. in (0.143 mm
2), to make light filaments (scalloped-oval cross-section). The smaller non-round capillaries
were located on the inner five (of 9) rings while the larger round capillaries were
located on the outer four rings of the spinneret. The orifice shape for the scalloped-oval
capillaries was essentially as described in U.S. application No. 08/662,804 (DP-6400)
and WO 97/02374 referred to hereinbefore. The molten filamentary streams were quenched
using radially-directed air from a profiled quench system, as described in Anderson,
et al., U.S. Patent No. 5,219,582. The resulting spun filament bundle consisted of
a mixture of different cross-sections and of lower and higher denier filaments with
properties indicated in Table 1A. Stress-strain curves of single filaments of the
two different types of filaments are shown in Figure 2, the continuous curve being
for a lower denier (light) filament of scalloped-oval (SO) cross-section, and the
interrupted curve being for a higher denier (heavy) round filament.
TABLE 1A
Filament |
|
|
|
|
Type |
Shape |
DPF |
Mod |
Ten |
EB % |
Light |
SO (1.37) |
1.6 (1.8) |
12.2 |
0.7 |
170 |
Heavy |
Round |
2.7 (3.0) |
13.8 |
0.7 |
131 |
[0032] Sixty-eight bobbins of the as-spun mixed filaments were combined to form a tow with
a nominal blend ratio of 40% scalloped-oval shape, lower dpf, and 60% round, higher
dpf, filaments. This tow was drawn at a draw ratio of 2.22X while sprayed with water
at 95°C. The tow was then passed through a stuffer box crimper and subsequently relaxed
at 145°C to give a final tow size of approximately 74,800 denier (83,100 dtex) of
an intimate blend of crimped filaments (10.6 CPI, 4.2 CPcm) of both types of filaments
whose properties are listed in Table IB.
[0033] A conventional finish was applied to provide a finish level (on fiber) of 0.15%.
The nominal denier per filament (i.e., the denier of the total tow bundle divided
by the number of filaments) was 1.1 dpf (1.3 dtex), about 40% of the filaments being
of scalloped-oval shape (0.98 denier) and the remaining 60% of round shape (1.19 denier).
[0034] The product was processed and then scrutinized for Product Defects, EFD, DDD and
SPL, all of which registered as zero Defects, so it is clear that the product quality
was not adversely impacted by simultaneously drawing a mixture of different shapes
and deniers of as-spun filaments, which was surprising and contrary to previous experience
in attempts to process filaments of mixed shape and mixed denier made essentially
similarly from homopolymer without chain-brancher, as will be related now.
COMPARISONS
[0035] In contrast, when four mixtures of different filaments of homopolymer 2G-T without
any chain-brancher were drawn similarly in the same bundles, significant Product Defects
were noted when the drawn bundles were processed and scrutinized, as indicated in
Table C2. The draw ratios are indicated as "DR" in Table C2. Each mixture that was
drawn together was a mixture of two types of filaments out of four types CA, CB, CC
and CD, whose properties are shown in Table C1. The filaments were spun separately
from the homopolymer 2G-T without any chain-brancher (LRV 20.4), but otherwise essentially
as described for Example 1.
TABLE C1
Item |
Shape |
DPF |
Mod |
Ten |
EB % |
NDR |
CA |
so (1.7) |
3.1 (3.4) |
15.4 |
1.8 |
199 |
1.9 |
CB |
so (1.7) |
10.4 (11.5) |
17.6 |
1.6 |
278 |
1.7 |
CC |
Round |
7.4 (8.2) |
16.6 |
1.6 |
245 |
1.9 |
CD |
so (1.7) |
7.4 (8.3) |
17.3 |
1.7 |
231 |
1.9 |
TABLE C2
Mixture |
DR |
EFD |
DDD |
CA/CB |
2.4X |
148 |
57 |
CA/CB |
2.8X |
108 |
54 |
CC/CD |
2.7X |
0 |
45 |
CC/CD |
3.0X |
0 |
27 |
[0036] The significant numbers of Product Defects resulting from drawing such mixed filaments
of homopolymer (CA/CB being mixtures of filaments of different deniers, but both of
scalloped-oval cross-section of modification ratio 1.7, and CC/CD being mixtures of
filaments of the same denier, but one being round and the other of scalloped-oval
cross-section of modification ratio 1.7) contrast with the zero Product Defects obtained
from Example 1 and from other Examples, according to the invention. Stress-strain
curves of single filaments of these four types of homopolymer, CA, CB, CC and CD,
are shown in Figure 3, and may be contrasted with the curves in Figure 2 and in Figures
4-6 for filaments of chain-branched polymer. Those in Figure 3 all have significant
flat portions that indicate a natural draw ratio for these homopolymer filaments,
as was well known. Their natural draw ratios are listed as "NDR" in Table C1. As can
be seen, the natural draw ratios for CC and CD are both 1.9X, i.e., are both the same,
but simultaneous drawing of mixtures of CC and CD gave significant numbers of Dark
Dye Defects. The curves in Figure 2 do not show corresponding flat portions; this
can explain, in retrospect, why such filaments can be drawn together and give products
without Product Defects, in contrast with the unsatisfactory prior experience in simultaneous
drawing of most mixed deniers and/or cross-sections (because the filaments were of
the homopolymer).
EXAMPLE 2
[0037] A mixture of three types of filaments, having different cross-sections but all of
7.6 dpf (8.4 dtex), was made by spinning each type separately at 282°C from polymer
containing 0.27% TES, 8.9 LRV and 15.4 NRV (6.5 ΔRV), at 1600 ypm (1460 m/min), but
otherwise essentially as described for Example 1, to give as-spun filaments whose
properties are given in Table 2A. The round filaments were extruded at a rate of 85.2
lbs/hr (38.7 Kg/hr) from a 520 capillary spinneret. The hollow filaments were extruded
at a rate of 80.4 lbs./hr (36.5 Kg/hr) from a 490 capillary spinneret, using an orifice
shape essentially as described in Figure 5B of U.S. Patent No. 5,356,582. The scalloped-oval
filaments were extruded at a rate of 73.8 lbs/hr (33.5 Kg/hr) from a 450 capillary
spinneret.
Stress/strain curves of single filaments of each type are shown in Figure 4, together
with a Curve 3C that is a stress-strain curve for a 6-grooved filament that is described
in Example 3 hereinafter.
TABLE 2A
Item |
Cross-Section |
Mod |
Ten |
EB % |
2A |
Round |
16 |
0.63 |
320 |
2B |
Hollow (7%) |
18 |
0.68 |
330 |
2C |
SO (1.5) |
16 |
0.56 |
275 |
Eleven bobbins of the round filaments, 11 bobbins of the hollow filaments and 12
bobbins of the scalloped-oval filaments were combined to form a tow having a nominal
blend ratio of 34% round, 33% hollow, and 33% scalloped-oval filaments with a total
tow spun denier of 125,476 (139,418 dtex). This tow was drawn, crimped and relaxed
essentially as described for Example 1, but at a draw ratio of 3.0X to give a drawn
tow of approximately 47,000 denier (52,000 dtex) of an intimate blend containing these
three differently-shaped crimped filaments (8.4 CPI, 3.3 CPcm, 16.7 CTU) with a nominal
dpf of about 2.85 (3.2 dtex) whose filament properties are listed in Table 2B.
TABLE 2B
Cross Section |
Conc. Wt % |
Mod |
Ten |
EB % |
Round |
34 |
44 |
2.2 |
15 |
Hollow |
33 |
49 |
2.3 |
12 |
S. Oval |
33 |
47 |
2.3 |
17 |
[0038] Conventional finish was applied as in Example 1, and the tow was processed and scrutinized
for Product Defects. It was surprising, in view of previous attempts with conventional
filaments, that the sliver resulting from this Example of an intimate blend of three
different cross-sections (round, hollow, and scalloped-oval), did not show any Product
Defects of EFD, DDD, and SPL, despite having been drawn simultaneously.
[0039] How a fabric feels to a consumer can be critical for commercial viability. A fabric's
aesthetics can be significantly affected by using mixtures of fibers of different
cross-sections. But, previously, it has not been possible to draw simultaneously such
mixtures of filaments from conventional homopolymers.
EXAMPLE 3
[0040] In Tables 3A and 3B, data are summarized for filaments as-spun and in a drawn tow
of three differently-shaped filaments (same dpf) that were prepared and processed
essentially as described in Example 2, but wherein the 2C scalloped-oval shape having
only 4 grooves was replaced by filaments 3C having a 6-grooved cross-section, as described
in U.S. Patent No. 5,626,961 (DP-6365-A). As explained in Example 2, a stress-strain
curve for such a filament of 6-grooved cross-section has been included in Figure 4
as Curve 3C, the round and hollow as-spun filaments being essentially the same for
both Examples 2 and 3.
TABLE 3A
Item |
Cross-Section |
Mod |
Ten |
EB % |
3A |
Round |
16 |
0.63 |
320 |
3B |
Hollow (7%) |
18 |
0.68 |
330 |
3C |
6-grooved |
16 |
0.60 |
300 |
TABLE 3B
Cross-Section |
Mod |
Ten |
EB % |
Round |
44 |
2.2 |
15 |
Hollow |
49 |
2.3 |
15 |
6-grooved |
47 |
2.3 |
16 |
[0041] The drawn tow (8.3 CPI, 3.3 CPcm, 19.9 CTU) of 2.85 nominal dpf (3.2 dtex) was processed
and showed zero Product Defects (EFD, DDD, SPL).
EXAMPLE 4
[0042] In Tables 4A and 4B, data are summarized similarly for filaments of four different
shapes that were prepared essentially as described in Example 2. Round filaments were
extruded at a rate of 70.4 lbs/hr (32 Kg/hr) from a 286 capillary spinneret; trilobal
filaments were extruded at a rate of 44 lbs/hr (20 Kg/hr) from a 160-capillary spinneret,
using an orifice shape essentially as described in Figure XI of U.S. Patent No. 2,945,739;
scalloped-oval (4 grooves) filaments were extruded at a rate of 110 lbs/hr (50 Kg/hr)
from a 450-capillary spinneret and hollow filaments were extruded at a rate of 89.4
lbs/hr (40.6 Kg/hr) from a 363-capillary spinneret. Stress/strain curves of single
filaments of these different cross sections are shown in Figure 5.
TABLE 4A
Item |
Cross-Section |
DPF |
Mod |
Ten |
EB % |
4A |
Round |
11.7 (13.0) |
21 |
0.67 |
314 |
4B |
Trilobal (1.4) |
11.5 (12.8) |
22 |
0.65 |
266 |
4C |
SO (1.5) |
11.4 (12.7) |
18 |
0.71 |
353 |
4D |
Hollow (7%) |
11.6 (12.9) |
19 |
0.67 |
328 |
TABLE 4B
Item |
Cross-Section |
DPF |
Mod |
Ten |
EB % |
4A |
Round |
4.9 (5.4) |
34 |
1.7 |
22 |
4B |
Trilobal |
3.8 (4.2) |
47 |
2.5 |
13 |
4C |
so |
4.3 (4.7) |
37 |
1.9 |
18 |
4D |
Hollow |
4.1 (4.6) |
41 |
2.3 |
17 |
[0043] Twenty bobbins of round filaments (66,924 denier, 74,360 dtex), thirty-five bobbins
of trilobal filaments (64,400 denier, 71,555 dtex), four bobbins of scalloped-oval
filaments (20,520 denier, 22,800 dtex), and five bobbins of hollow filaments (21,054
denier, 23,393 dtex) were combined to form a tow having nominal blend ratio of 39%
round, 37% trilobal, 12% scalloped-oval and 12% hollow filaments with a total denier
of 172,898 (192,108 dtex). The tow was drawn, crimped and relaxed essentially as described
in Example 2 to give a drawn tow of approximately 64,490 denier (71,655 dtex) of an
intimate blend containing these four differently-shaped crimped (8.9 CPI, 3.5 CPcm,
20 CTU) filaments - round, trilobal, scalloped-oval, and hollow - with a nominal 4.3
dpf (4.8 dtex). Filament properties are listed in Table 4B. The drawn dpfs were significantly
different although the spun dpfs were very similar, which shows the difficulty of
predicting beforehand what will happen when mixed filaments are drawn together.
[0044] Conventional finish was applied as in Example 1. The drawn tow was processed to show
zero Product Defects (EFD, DDD, SPL).
[0045] A magnified photograph of part of this mixture of filaments is shown in Figure "1".
EXAMPLE 5
[0046] In Table 5, drawn filament properties are summarized similarly for filaments of only
two differently-shaped drawn filaments from a drawn tow prepared essentially as described
in Example 4 except that only two different cross-sections - round and trilobal -
were combined similarly, in proportions of round fibers - 51%, and trilobal fibers
- 49%.
TABLE 5B
Item |
Cross-Section |
Conc. % |
Doffs |
DPF |
Mod |
Ten |
EB % |
4A |
Round |
51 |
20 |
4.5 (5.0) |
27 |
1.9 |
13 |
4B |
Trilobal |
49 |
35 |
4.3 (4.8) |
39 |
2.1 |
15 |
[0047] The crimp was measured as 8.9 CPI, 3.5 CPcm and 22.5 CTU. The tow was processed to
show zero Product Defects (EFD, DDD, SPL), despite the drawn dpfs and filament properties
being significantly different from those in Table 4B. This confirms the difficulty
of predicting behavior of filaments during drawing.
EXAMPLE 6
[0048] Filaments of round, trilobal, and scalloped-oval cross-section of two different deniers
(higher dpf termed "SO-H" and lower dpf termed "SO-L"), were melt spun essentially
as described for Example 4 (no hollow filaments being used in this Example); the SO-L
filaments were extruded at a rate of 75 lbs/hr (34 Kg/hr) from a 450-capillary spinneret;
the SO-H and the other filaments were as described for Example 4. The spun denier
of the round, trilobal, and SO-H filaments were approximately the same while the SO-L
were 7.9 dpf (8.8 dtex). The as-spun properties are indicated in Table 6A. Stress/strain
curves of single filaments of both scalloped-oval types are shown in Figure 6, the
continuous line being for a SO-H higher denier filament, and the interrupted line
being for a lower denier SO-L filament.
[0049] Twenty bobbins of round filaments, thirty-five bobbins of trilobal filaments and
four bobbins of SO-H filaments (as for Example 4) were combined with five bobbins
of SO-L filaments (17,775 denier, 19,750 dtex) to form a tow having a nominal blend
ratio of 40% round, 38% trilobal, 12% SO-H and 10% SO-L with a total tow denier of
169,619 (188,466 dtex). Part of this tow was drawn, crimped and relaxed essentially
as in Example 2 to give a drawn tow (8.7 CPI, 3.4 CPcm, 14.8 CTU) of approximately
57,018 denier (63,353 dtex) of an intimate blend containing round, trilobal, scalloped-oval
higher dpf, all of 3.9 dpf (4.3 dtex) and scalloped-oval lower dpf of 2.6 dpf (2.9
dtex) whose filament properties are listed in the upper part of Table 6B. Another
portion of the same tow was processed through another route, using in addition an
annealer at 145°C, before the stuffer box crimper, and then relaxed at 145°C to give
a drawn tow (11.6 CPI, 3.0 CPcm, 10.7 CTU) of filaments whose properties are listed
in the lower part of Table 6B.
TABLE 6A
Cross-Section |
DPF |
Mod |
Ten |
EB % |
Round |
11.7 (13.0) |
21 |
0.67 |
314 |
Trilobal (1.4) |
11.5 (12.8) |
22 |
0.65 |
266 |
SO-H (1.5) |
11.4 (12.7) |
18 |
0.71 |
353 |
SO-L (1.5) |
7.9 (8.8) |
20 |
0.69 |
316 |
TABLE 6B
Cross-Section |
Mod |
Ten |
EB % |
Relaxed |
|
|
|
Round |
37 |
1.7 |
14 |
Trilobal |
32 |
1.5 |
15 |
SO-H |
37 |
1.9 |
18 |
SO-L |
39 |
2.2 |
21 |
Annealed |
|
|
|
Round |
41 |
2.0 |
11 |
Trilobal |
32 |
1.9 |
12 |
SO-H |
41 |
2.4 |
14 |
SO-L |
41 |
2.5 |
15 |
[0050] Conventional finish was applied as in Example 1. Both drawn tows were processed and
showed zero Product Defects (EFD, DDD, SPL), again despite the filaments having significantly
different properties from those drawn in other Examples.
EXAMPLE 7 (Comparative)
[0051] Mixed filaments, both of scalloped-oval cross-section were spun from the same spinneret
essentially as described in Example 1, but using polymer as described in Example 2,
the 516 large capillaries (located on the outer four rings of the spinneret) being
of flow area 0.0002717 sq. in. (0.175 mm
2) to make the heavy dpf SO filaments. Table 7A shows as-spun properties obtained for
the resulting light and heavy dpf filaments.
TABLE 7A
Thruput/ lbs |
Type |
DPF |
Mod |
Ten |
EB % |
92 (42) |
Light (1.3) |
3.5 (3.9) |
12 |
0.6 |
175 |
|
Heavy (1.4) |
4.6 (5.2) |
11 |
0.7 |
291 |
[0052] Thirty-four bobbins were combined to form a tow with a nominal blend ratio of 40/60
light/heavy filaments. This tow was drawn at a ratio of 2.6X but otherwise drawn,
crimped and relaxed essentially as described in Example 1 to give a drawn tow of approximately
56,000 denier (62,000 dtex) of an intimate blend containing lower and higher denier
filaments, with a nominal dpf of about 1.85 (2.1 dtex), whose filament properties
are listed in Table 7B.
[0053] Conventional finish was applied as in Example 1. The tow (CPI 9.6, CPcm 3.8) was
collected in a conventional tow box and sent to a mill for downstream processing,
blending with wool for yarn conversion and then into fabrics, and processed very satisfactorily,
showing zero Product Defects (EFD, DDD, SPL). This Example 7 is similar to Example
1 of U.S. Patent No. 5,591,523 in that filaments of scalloped-oval cross-section of
differing deniers were simultaneously drawn in the same bundle, but different in that
in the present Example 7 both types of filaments were made by spinning through different
capillaries in the same spinneret.
[0054] The absence of any such Product Defects in drawn mixed filament tow bundles according
to the invention is very different from experience when drawing comparable mixed filament
bundles of polyester homopolymer (2G-T) without any chain-brancher.
1. Verfahren zur gleichzeitigen Verstreckung einer Polyesterfilamentmischung in demselben
Bündel Polyesterfilamente, wobei die genannte Mischung eine Mischung aus Filamenten
mit unterschiedlichen Querschnitten ist, die Mischung Polyesterfilamente mit Querschnitten
umfaßt, die ausgewählt sind aus wenigstens zwei der folgenden Querschnittstypen: ausgebogt
oval, trilobal, bandförmig, massiv, hohl, mehrfach-hohl und rund, und wobei der genannte
Polyester mit 0,1 bis 0,8 Mol-% Kettenverzweiger kettenverzweigt ist.
2. Verfahren nach Anspruch 1, wobei die Filamentmischung Filamente umfaßt, die eine der
folgenden Querschnittskombinationen besitzen: ausgebogt oval und rund; rund, hohl
und ausgebogt oval; rund, hohl und ausgebogt oval gerillt; rund, trilobal, ausgebogt
oval und hohl; rund und trilobal; und rund, trilobal und ausgebogt oval.
3. Verfahren nach Anspruch 1, wobei die Polyesterfilamentmischung Filamente mit unterschiedlichen
Denier-Werten pro Filament umfaßt.
4. Verfahren nach Anspruch 3, wobei ein erstes Filament in der Mischung einen Denier-Wert
pro Filament besitzt, der wenigstens 1,1mal größer ist als der Denier-Wert pro Filament
eines zweiten Filaments.
5. Verfahren nach Anspruch 1, wobei die Filamente durch Kapillare mit wenigstens zwei
unterschiedlichen Querschnitten gezogen werden.
6. Eine Polyesterfilamentmischung, wobei die genannte Mischung eine Mischung aus Filamenten
mit unterschiedlichen Querschnitten ist, die Mischung Polyesterfilamente mit Querschnitten
umfaßt, die ausgewählt sind aus wenigstens zwei der folgenden Querschnittstypen: ausgebogt
oval, trilobal, bandförmig, massiv, hohl, mehrfach-hohl und rund, und wobei der genannte
Polyester mit 0,1 bis 0,8 Mol-% Kettenverzweiger kettenverzweigt ist, und wobei der
Kochschrumpf 0,5 bis 3% beträgt.
7. Mischung nach Anspruch 6, wobei die Filamentmischung Filamente umfaßt, die eine der
folgenden Querschnittskombinationen besitzen: ausgebogt oval und rund; rund, hohl
und ausgebogt oval; rund, hohl und ausgebogt oval gerillt; rund, trilobal, ausgebogt
oval und hohl; rund und trilobal; und rund, trilobal und ausgebogt oval.
8. Mischung nach Anspruch 6, wobei die genannte Mischung eine Mischung aus unterschiedlichen
Denier-Werten pro Filament ist.
9. Mischung nach Anspruch 8, wobei ein erstes Filament in der Mischung einen Denier-Wert
pro Filament besitzt, der wenigstens 1,1mal größer ist als der Denier-Wert pro Filament
eines zweiten Filaments.
10. Polyesterfilamentmischung, die durch gleichzeitiges Verstrecken einer Polyesterfilamentmischung
in demselben Bündel Polyesterfilamente erhalten werden kann, wobei die genannte Mischung
eine Mischung aus Filamenten mit unterschiedlichen Querschnitten ist, die Mischung
Polyesterfilamente mit Querschnitten umfaßt, die ausgewählt sind aus wenigstens zwei
der folgenden Querschnittstypen: ausgebogt oval, trilobal, bandförmig, massiv, hohl,
mehrfach-hohl und rund, und wobei der genannte Polyester mit 0,1 bis 0,8 Mol-% Kettenverzweiger
kettenverzweigt ist, und wobei der Kochschrumpf 0,5 bis 3% beträgt.
1. Procédé d'étirage simultané d'un mélange de filaments de polyester dans le même faisceau
de filaments de polyester, dans lequel ledit mélange est un mélange de filaments à
sections transversales différentes, le mélange incluant des filaments de polyester
ayant des sections transversales choisies parmi au moins deux des sortes suivantes
de sections transversales : festonné-oval; trilobé ; en forme de ruban ; plein ; creux
; multi-vide ; et rond, et dans lequel ledit polyester est à chaîne ramifiée avec
0,1 à 0,8 % en moles de ramificateur de chaîne.
2. Procédé selon la revendication 1, dans lequel le mélange de filaments comprend des
filaments ayant l'une des combinaisons suivantes de sections transversales: festonné-oval
et rond ; rond, creux et festonné-oval ; rond, creux et festonné-oval à rainure; rond,
trilobé, festonné-oval et creux ; rond et trilobé; et rond, trilobé et festonné-oval.
3. Procédé selon la revendication 1, dans lequel le mélange de filaments de polyester
inclut des filaments à différents deniers par filament.
4. Procédé selon la revendication 3, dans lequel un premier filament dans le mélange
a un denier par filament qui est au moins 1,1 fois plus grand que le denier par filament
d'un second filament.
5. Procédé selon la revendication 1, dans lequel les filaments sont étirés à travers
des capillaires d'au moins deux sections transversales différentes.
6. Mélange de filaments de polyester, ledit mélange étant un mélange de filaments à sections
transversales différentes, le mélange incluant des filaments de polyester ayant des
sections transversales choisies parmi au moins deux des sortes suivantes de sections
transversales: festonné-oval ; trilobé; en forme de ruban ; plein ; creux ; multi-vide
; et rond, et dans lequel ledit polyester est à chaîne ramifiée avec 0,1 à 0,8 % en
moles de ramificateur de chaîne, et dans lequel le retrait par ébullition est de 0,5
à 3 %.
7. Mélange selon la revendication 6, dans lequel le mélange de filaments comprend des
filaments ayant l'une des combinaisons suivantes de sections transversales : festonné-oval
et rond; rond, creux et festonné-oval ; rond, creux et festonné-oval à rainure; rond,
trilobé, festonné-oval et creux; rond et trilobé; et rond, trilobé et festonné-oval.
8. Mélange selon la revendication 6, ledit mélange étant un mélange à différents deniers
par filament.
9. Mélange selon la revendication 8, dans lequel un premier filament dans le mélange
a un denier par filament qui est au moins 1,1 fois plus grand que le denier par filament
d'un second filament.
10. Mélange de filaments de polyester, susceptible d'être obtenu par étirage simultané
d'un mélange de filaments de polyester dans le même faisceau de filaments de polyester,
dans lequel ledit mélange est un mélange de filaments de sections transversales différentes,
le mélange incluant des filaments de polyester ayant des sections transversales choisies
parmi au moins deux des sortes suivantes de sections transversales : festonné-oval
; trilobé ; en forme de ruban ; plein ; creux ; multi-vide ; et rond, et dans lequel
ledit polyester est à chaîne ramifiée avec 0,1 à 0,8 % en moles de ramificateur de
chaîne, et dans lequel le retrait par ébullition est de 0,5 à 3 %.