U.S. patent application number 10/301343 was filed with the patent office on 2004-05-27 for polyester bicomponent filament.
Invention is credited to Chang, Jing-Chung, Kurian, Joseph V., Van Trump, James E..
Application Number | 20040099984 10/301343 |
Document ID | / |
Family ID | 32324525 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040099984 |
Kind Code |
A1 |
Chang, Jing-Chung ; et
al. |
May 27, 2004 |
Polyester bicomponent filament
Abstract
The invention provides an improved method for making a
poly(ester) bicomponent fiber wherein at least one poly(ester)
contains a styrene polymer.
Inventors: |
Chang, Jing-Chung;
(Boothwyn, PA) ; Kurian, Joseph V.; (Hockessin,
DE) ; Van Trump, James E.; (Wilmington, DE) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
32324525 |
Appl. No.: |
10/301343 |
Filed: |
November 21, 2002 |
Current U.S.
Class: |
264/172.14 ;
264/172.17; 264/210.5; 264/211.12; 264/211.14 |
Current CPC
Class: |
D01F 8/14 20130101 |
Class at
Publication: |
264/172.14 ;
264/172.17; 264/211.12; 264/211.14; 264/210.5 |
International
Class: |
D01D 005/32; D01D
005/088; D01D 005/16; D01D 010/02; D01F 006/62 |
Claims
What is claimed is:
1. A process for making a side-by-side bicomponent filament
comprising the steps of: a) providing poly(trimethylene
terephthalate); b) providing a polyester selected from the group
consisting of poly(ethylene terephthalate) and copolyesters of
poly(ethylene terephthalate), in a weight ratio of about 30/70 to
70/30; c) providing a styrene polymer having a number-average
molecular weight of about 75,000 daltons to 300,000 daltons; d)
mixing the styrene polymer with at least one of the
poly(trimethylene terephthalate) of step (a) and the selected
polyester of step (b) to form a first melt-extrusion polymer and a
second melt-extrusion polymer, respectively, wherein at least one
melt-extrusion polymer contains from about 0.1 weight percent to
about 5 weight percent styrene polymer; e) melting the first
melt-extrusion polymer; f) melting the second melt-extrusion
polymer; g) spinning the first and second melt-extrusion polymers a
filament; h) quenching the filament with gas in a manner selected
from the group consisting of cross-flow and co-current flow; i)
withdrawing the filament; and j) winding up the filament.
2. The process of claim 1 further comprising, between steps h) and
i) the steps of drawing the filament by at about 2.0X to 4.5X and
heat-treating the filament at about 140.degree. C. to 185.degree.
C. to form a fully-drawn filament, wherein step i) is carried out
at a speed of at least about 4100 m/min when the quench gas is
supplied as cross-flow and at least about 6200 m/min when the
quench gas is supplied as co-current flow, and the wound-up
filament has an after heat-set crimp contraction value of at least
about 30%.
3. The process of claim 2 wherein winding step j) is carried out at
about 5300 to 5800 m/min when the quench gas is cross-flow and at
about 8200 to 9000 m/min when the quench gas is co-current
flow.
4. The process of claim 1 wherein withdrawing step i) is carried
out at a speed of about 3000 to 4500 m/min when the quench gas is
cross-flow and at a speed of about 3600 to 5000 m/min when the
quench gas is co-current flow, and the filament in step i) is
partially oriented.
5. The process of claim 4 further comprising, after step i), the
steps of drawing the filament by about 2.0X to 4.5X and
heat-treating the filament at about 140.degree. C. to 185.degree.
C.
6. The process of claim 4 wherein the withdrawing speed is about
3500 to 4500 m/min when the quench gas is cross-flow and the
withdrawing speed is about 4100 to 5000 m/min when the quench gas
is co-current flow.
7. The process of claim 1 wherein quenching step h) is carried out
with cross-flow quench gas, withdrawing step i) is carried out at a
speed of about 6000 to 8000 m/min, and a fully oriented filament is
wound up in step j) at about 6000 to 8000 m/min.
8. The process of claim 7 wherein the filament has an
after-heat-set crimp contraction value of at least about 30%.
9. The process of claim 1 wherein the styrene polymer is present at
about 0.5 to about 4 weight percent based on the mixture.
10. The process of claim 1 wherein the styrene polymer is
polystyrene having a number-average molecular weight of about
100,000 to 200,000 daltons.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to bicomponent filaments,
particularly to a process for making bicomponent filaments, more
particularly to a process wherein such bicomponent filaments
contain a small amount of styrene polymer additive.
[0003] 2. Discussion of Background Art
[0004] Spinning of bicomponent polyester fibers has been disclosed
in U.S. Pat. No. 3,671,379 (which shows a `snowman` fiber
cross-section in FIG. 4), Published World Patent Application
WO2001-53573 and Published United States Patent Application
US2001-0055683. Spinning polyester fiber containing polystyrene has
been disclosed in Published Japanese Patent Application JP56-91013
and U.S. Pat. No. 4,424,258. Published Japanese Patent Application
JP57-61716, misquoted in published Published Japanese Patent
Application JP59-26524, discloses the use of blends of polyesters
with polyacrylates, polystyrene, or polymethacrylates to make mixed
filaments, in which two polymer streams are spun simultaneously but
separately to form two distinct groups of different filaments. The
latter application teaches away from using such blends to make
side-by-side bicomponent fibers. Published Japanese Patent
Application JP11-189925 discloses spinning and twisting a fiber
having a small core of polystyrene/polyester blend in a sheath of
the same polyester in order to avoid reported "melt fusion" in
subsequent processing.
[0005] There remains a need to make high-crimp, side-by-side,
bicomponent fibers at high speeds.
SUMMARY OF THE INVENTION
[0006] The present invention provides a process for making a
side-by-side bicomponent filament comprising the steps of:
[0007] a) providing poly(trimethylene terephthalate);
[0008] b) providing a polyester selected from the group consisting
of poly(ethylene terephthalate) and copolyesters of poly(ethylene
terephthalate), in a weight ratio of about 30/70 to 70/30;
[0009] c) providing a styrene polymer having a number-average
molecular weight of about 75,000 daltons to 300,000 daltons;
[0010] d) mixing the styrene polymer with at least one of the
poly(trimethylene terephthalate) of step (a) and the selected
polyester of step (b) to form a first melt-extrusion polymer and a
second melt-extrusion polymer, respectively, wherein at least one
melt-extrusion polymer contains from about 0.1 weight percent to
about 5 weight percent styrene polymer;
[0011] e) melting the first melt-extrusion polymer;
[0012] f) melting the second melt-extrusion polymer;
[0013] g) spinning the first and second melt-extrusion polymers
into a filament;
[0014] h) quenching the filament with gas in a manner selected from
the group consisting of cross-flow and co-current flow;
[0015] i) withdrawing the filament; and
[0016] j) winding up the filament.
BRIEF DESCRIPTION OF THE FIGURES
[0017] FIG. 1 shows a quench system that can be used in a process
of the invention.
[0018] FIG. 2 shows a roll system that can be used in a process of
the invention.
[0019] FIG. 3 illustrates fully drawn filament crimp values
obtained at various windup speeds in a process of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] In contrast to the disclosures of the prior art, it has now
been found that side-by-side bicomponent filaments comprising
poly(ethylene terephthalate) and poly(trimethylene terephthalate)
with a small amount of styrene polymer additive can be spun at
unexpectedly high speeds without sacrificing desirable crimp. In
further contrast to the prior art, no melting or sticking was
observed during processing of the filament, for example during
drawing, winding, testing, and the like, even when no particular
precaution was taken to prevent the polystyrene from being present
at the surface of the filament. As a result of the high degree of
crimp in the filament, it was not necessary to twist the filament
to make it useful.
[0021] As used herein, "bicomponent filament" means a continuous
filament comprising polyesters of different chemical composition,
specifically poly(ethylene terephthalate) and poly(trimethylene
terephthalate), adhered to each other along the length of the
filament in a side-by-side relationship. "Withdrawal speed" means
the speed of the feed rolls, which are positioned between the
quench zone and the (optional) draw rolls and is sometimes referred
to as the spinning speed. "IV" means intrinsic viscosity. "Fully
drawn" filament means a bicomponent filament which is suitable for
use, for example, in weaving, knitting, and preparation of
nonwovens without further drawing and can exhibit useful crimp
contraction values. "Partially oriented" filament means a filament
which has considerable but not complete molecular orientation, for
example having considerable residual draw, and which generally
requires drawing or draw-texturing before it is suitable for
weaving or knitting and before it can exhibit useful crimp
contraction values. "Fully oriented" filament means a filament
which, as-spun, requires no drawing to be useful or to exhibit
useful crimp contraction values. "Co-current gas flow" means a flow
of quench gas which is accelerated in the direction of filament
travel.
[0022] In the process of the present invention, a small amount of
styrene polymer additive is mixed with at least one of a)
poly(trimethylene terephthalate) and b) poly(ethylene
terephthalate) or copolyesters of poly(ethylene terephthalate). The
mixture can be made by `salt-and-pepper` blending, optionally
followed by compounding, for example in an extruder. The
poly(ethylene terephthalate) or copolyester thereof, or mixture of
styrene polymer with poly(ethylene terephthalate) or copolyester
thereof (the `second melt-extrusion polymer`), is then melt-spun
with poly(trimethylene terephthalate) or mixture of styrene polymer
and poly(trimethylene terephthalate) (the `first melt-extrusion
polymer`) in a weight ratio of 70/30 to 30/70 to form a
side-by-side bicomponent filament, and the filament is quenched,
withdrawn, and wound up. The styrene polymer is present in one
component, and can be present in both components, of the
bicomponent filament. The styrene polymer additive is present at a
level of 0.1 to about 5 weight percent, typically about 0.5 to
about 4 weight percent, based on weight of the mixture.
[0023] The poly(ethylene terephthalate) or copolyester thereof can
have an IV of about 0.45-0.80 dl/g and the poly(trimethylene
terephthalate) can have an IV of about 0.85-1.50 dl/g. A
copoly(ethylene terephthalate) can be used in which the comonomer
used to make the copolyester is selected from the group consisting
of linear, cyclic, and branched aliphatic dicarboxylic acids having
4-12 carbon atoms (for example butanedioic acid, pentanedioic acid,
hexanedioic acid, dodecanedioic acid, and
1,4-cyclo-hexanedicarboxylic acid); aromatic dicarboxylic acids
other than terephthalic acid and having 8-12 carbon atoms (for
example isophthalic acid and 2,6-naphthalenedicarboxylic acid);
linear, cyclic, and branched aliphatic diols having 3-8 carbon
atoms (for example 1,3-propane diol, 1,2-propanediol,
1,4-butanediol, 3-methyl-1,5-pentanediol,
2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, and
1,4-cyclohexanediol); and aliphatic and araliphatic ether glycols
having 4-10 carbon atoms (for example, hydroquinone
bis(2-hydroxyethyl) ether, or a poly(ethyleneether) glycol having a
molecular weight below about 460, including diethyleneether
glycol). The comonomer can be present in the copolyester at levels
of about 0.5-15 mole percent. Isophthalic acid, pentanedioic acid,
hexanedioic acid, 1,3-propane diol, and 1,4-butanediol are
preferred.
[0024] Either or both polyesters can contain minor amounts of other
comonomers, provided such comonomers do not have an adverse affect
on the spinning speed, filament crimp value, or other properties.
Such other comonomers include 5-sodium-sulfoisophthalate, at a
level of about 0.2-5 mole percent, and very small amounts of
trifunctional comonomers such as trimellitic acid. Poly(ethylene
terephthalate) and poly(trimethylene terephthalate) include such
copolyesters thereof within their meaning
[0025] The styrene polymer additive has a number average molecular
weight of at least about 75,000 daltons, typically at least about
100,000 daltons and at most about 300,000 daltons, more typically
at most about 200,000 daltons. Useful styrene polymers can be
isotactic, atactic, or syndiotactic; especially at higher molecular
weights, atactic is preferred. The styrene polymer can be selected
from the group consisting of polystyrene, alkyl- or
aryl-substituted polystyrenes (for example prepared from
.quadrature.-methylstyrene, p-methoxystyrene, and vinyltoluene),
copolymers of styrene and substituted styrene, and styrene
multicomponent polymers such as styrene-butadiene copolymers.
Polystyrene ("PS") is preferred.
[0026] The poly(trimethylene terephthalate) ("3G-T"), poly(ethylene
terephthalate) ("2G-T"), styrene polymer additive, and/or the
mixtures thereof, can, if desired, contain additives, such as
delusterants, nucleating agents, heat stabilizers, viscosity
boosters, optical brighteners, pigments, and antioxidants. For
example, TiO.sub.2 or other pigments can be added to the
poly(trimethylene terephthalate), the poly(ethylene terephthalate),
the styrene polymer additive, the mixture(s), or during filament
manufacture.
[0027] After being spun from a spinneret, the hot filament can be
quenched with a gas supplied as cross-flow or co-current flow. In
cross-flow, the gas can be blown across the just-spun filaments,
for example from one side of a quench chamber as shown in FIG. 1.
In co-current flow, quench gas can be introduced from above, for
example from an annular space around the spinneret, or from the
side as shown in FIG. 2 of U.S. Pat. No. 5,824,248 and FIGS. 2, 4,
and 6 of Published United States Patent US-2002-0025433, which are
incorporated herein by reference. The quench gas can be accelerated
in the direction of filament travel, for example by supplying the
gas at elevated pressure and using a constriction below the quench
chamber through which both the gas and the filaments pass. The
resulting superatmospheric pressure can be in the range of about
0.5-5.0 inches of water (about 1.3.times.10.sup.-3 to
1.3.times.10.sup.-2 kg/cm.sup.2. The maximum velocity of the quench
gas is generally at the narrowest point of the constriction. When a
constriction having a minimum inner diameter of one inch (2.54 cm)
is used, the maximum gas velocity can be in the range of about
330-5,000 meters/minute. Subatmospheric pressure can also be used.
Optionally, a flow of quench gas into each of two substantially
coaxial quench chambers arranged in series along the path of the
filaments and each chamber provided with a constriction through
which gas and filaments pass, can be used.
[0028] In one embodiment of the invention, the spun filament is
drawn by about 2.0X to 4.5X and heat-treated at about 140.degree.
C. to 185.degree. C. to form a fully-drawn filament before being
wound up. When the quench gas is supplied as cross-flow, the windup
speed is at least about 4100 m/min, typically about 5300 to 5800
m/min. When the quench gas is supplied as co-current flow, the
windup speed is at least about 6200 m/min, preferably about 8200 to
9000 m/min. Such a filament can have an after-heat-set crimp
contraction value of at least about 30%.
[0029] In another embodiment of the invention, the filament is spun
with quench gas supplied as cross-flow at withdrawal speeds of
about 3000 to 4500 m/min, typically about 3500 to 4500 m/min, or as
co-current flow at withdrawal speeds of about 3600 to 5000 m/min,
typically about 4100 to 5000 m/min and wound up as a partially
oriented filament, for example with little or no drawing. The
partially oriented filament can be further processed later, for
example drawn by about 2.0X to 4.5X and heat-treated at about
140.degree. C. to 185.degree. C., typically within about 35 days.
At lower withdrawal speeds but still within the scope of the
present invention, shorter delays between spinning and
drawing/heat-treating would typically be used.
[0030] In yet another embodiment, the filament is spun with
cross-flow quench at withdrawal speeds of at least about 6000 to
8000 m/min and a fully oriented filament is wound up at
substantially the same speed. Such filament typically has an
after-heat-set crimp contraction value of at least about 30%.
[0031] Higher levels of styrene polymer additive generally permit
higher withdrawal and windup speeds, as does the use of styrene
polymer additive mixed into both the poly(ethylene terephthalate)
(or copolyester thereof) and the poly(trimethylene
terephthalate).
[0032] The filaments can have cross-sections that are round,
`snowman`, octalobal, scalloped oval, trilobal, tetra-channel (also
known as quatra-channel), and the like.
[0033] The crimp values of the bicomponent filaments made in the
Examples was measured as follows. Each sample was formed into a
skein totaling 5000+/-5 denier (5550 dtex) with a skein reel at a
tension of about 0.1 gpd (0.09 dN/tex). The skein was conditioned
at 70+/-2.degree. F. (21+/-1.degree. C.) and 65+/-2% relative
humidity for a minimum of 16 hours. The skein was hung
substantially vertically from a stand, a 1.5 mg/den (1.35 mg/dtex)
weight (e.g. 7.5 grams for a 5550 dtex skein) was hung on the
bottom of the skein, the weighted skein was allowed to come to an
equilibrium length, and the length of the skein was measured to
within 1 mm and recorded as "C.sub.b". The 1.35 mg/dtex weight was
left on the skein for the duration of the test. Next, a 500 gram
weight (100 mg/d; 90 mg/dtex) was hung from the bottom of the
skein, and the length of the skein was measured to within 1 mm and
recorded as "L.sub.b". Crimp contraction value (percent) (before
heat-setting, as described below for this test), "CC.sub.b", was
calculated according to the formula
CC.sub.b=100.times.(L.sub.b-C.sub.b)/L.sub.b
[0034] The 500 g weight was removed, and the skein was then hung on
a rack and heat-set, with the 1.35 mg/dtex weight still in place,
in an oven for 5 minutes at about 250.degree. F. (121.degree. C.),
after which the rack and skein were removed from the oven and
conditioned as above for two hours. This step is designed to
simulate commercial dry heat-setting, which is one way to develop
the final crimp in the bicomponent filament. The length of the
skein was measured as above, and its length was recorded as
"C.sub.a". The 500-gram weight was again hung from the skein, and
the skein length was measured as above and recorded as "L.sub.a".
The after heat-set crimp contraction value (percent), "CC.sub.a",
was calculated according to the formula
CC.sub.a=100.times.(L.sub.a-C.sub.a)L.sub.a.
[0035] The test was performed on five samples and the results were
averaged. CC.sub.a is reported in the Tables. This crimp
measurement method is estimated to be accurate to .+-.2 percent
absolute.
[0036] The poly(trimethylene terephthalate) used in the Examples
was prepared from 1,3-propanediol and dimethylterephthalate ("DMT")
in a two-vessel process using tetraisopropyl titanate catalyst,
Tyzor.RTM. TPT (a registered trademark of E. I. du Pont de Nemours
and Company) at 60 ppm titanium, based on polymer. Molten DMT was
added to 3G and catalyst at 185.degree. C. in a transesterification
vessel, and the temperature was increased to 210.degree. C. while
methanol was removed. The resulting intermediate was transferred to
a polycondensation vessel where the pressure was reduced to one
millibar (10.2 kg/cm.sup.2), and the temperature was increased to
255.degree. C. When the desired melt viscosity was reached, the
pressure was increased and the polymer was extruded, cooled, and
cut into pellets. The pellets were further polymerized in a
solid-phase polymerizer to an intrinsic viscosity of 1.03 dl/g in a
tumble dryer operated at 212.degree. C.
[0037] The polystyrene used in the Examples was `168 MK G2` from
BASF; it was reported to be a homopolymer and to have a melt index
of 1.5 g per 10 min as determined according to ASTM 1238 on 5 kg at
200.degree. C. and a softening point of 109.degree. C. as
determined according to ASTM-D1525. It had a number-average
molecular weight of 124,000 daltons as calculated according to ASTM
D 5296-97.
[0038] The spinneret used in the examples was a post-coalescence
bicomponent spinneret having thirty-four pairs of capillaries
arranged in a 1.75 inch (4.4 cm) diameter radially symmetric
circle, an internal convergent angle between each pair of
capillaries of 60.degree., a capillary diameter of 0.64 mm, and a
capillary length of 4.24 mm.
[0039] FIG. 1 illustrates the cross-flow quench chamber used in the
Examples. Quench gas 1 entered zone 2 below spinneret face 3
through plenum 4, past hinged baffle 18 and through screens 5 the
top 2.5 cm of which were not perforated, resulting in a
substantially laminar gas flow across still-molten filaments 6
which were spun from capillaries (not shown) in the spinneret.
Baffle 18 was hinged at the top, and its position was adjusted to
give the flow of quench gas shown in Table A, measured 5 inches
(12.7 cm) from screen 5.
1 TABLE A Distance below Air speed spinneret (cm) (mpm) 15 8.5 30
9.4 46 9.4 61 11.0 76 11.0 91 11.3 107 11.6 122 16.5 137 34.1 152
39.6 168 29.6
[0040] Spinneret face 3 was recessed above the top of zone 2 by
0.75 inch (1.9 cm) (distance "A" in FIG. 1), so that the quench gas
did not blow directly onto the face of the spinneret. The quench
gas, which was unheated air, continued on past the filaments and
into the space surrounding the apparatus. The filament left zone 2
through filament exit 7. Finish was applied to the filaments by
finish roll 10, and the filaments were then passed to the rolls
illustrated in FIG. 2.
[0041] As shown in FIG. 2, filament 6 was passed by finish roll 10,
around the pair of driven roll 11 and idler bearing 12, and then
around heated feed rolls 13. The temperature of feed rolls 13 was
about 60.degree. C. The filament was drawn by heated draw rolls 14,
heat-treated at substantially constant length by rolls 15, passed
around unheated rolls 16 (which adjusted the yarn tension for
satisfactory winding), and then to windup 17. The speeds of the
heat-treating rolls and draw rolls were substantially equal.
[0042] In the Examples, the draw ratio applied was the maximum
possible without generating a significant increase in the number
and/or frequency of broken filaments and was typically at about 90%
of break-draw. In the Tables, "Comp." indicates a comparison
sample, and "CCa" represents after-heat-set contraction in
percent.
EXAMPLES
Example 1
[0043] Polystyrene pellets were separately mixed with poly(ethylene
terephthalate) flake (0.54 IV Crystar.RTM. 4415, a registered
trademark of E. I. du Pont de Nemours and Company) and with the
poly(trimethylene terephthalate) prepared as described hereinabove.
The amount of polystyrene used was 2 weight percent in each case,
based on total polymer. Each mixture was separately compounded
using a conventional screw remelting compounder with a barrel
diameter of 30 mm and a MOCA-2 screw (Werner & Pfleiderrer
Corp., Ramsey, N.J.). The extrusion die was 1/8 inches (3.18 mm) in
diameter with a screen filter at the die entrance. A vacuum was
typically applied at the extruder throat.
[0044] For the mixture of polystyrene with poly(ethylene
terephthalate), the first barrel section of the compounder was set
at 170.degree. C., the second section at 230.degree. C., and the
remaining ten sections at 220.degree. C. The screw was operated at
150 revolutions per minute, and the melt temperature was
266.degree. C. at the extrusion die.
[0045] For the mixture of polystyrene with poly(trimethylene
terephthalate), the first heated barrel section was set at
170.degree. C., the second at 230.degree. C., and the remaining ten
sections at 215.degree. C. The screw was set at 150 revolutions per
minute, and the melt temperature was 261.degree. C. at the
extrusion die.
[0046] In each case, the extrudant then flowed into a waterbath to
solidify the mixed polymers into a monofilament. Two sets of air
knives dewatered the filament, and it was passed to a cutter that
sliced it into 2 mm pellets.
Example 2
[0047] The pellets of poly(ethylene terephthalate) mixed with 2 wt
% polystyrene and the pellets of poly(trimethylene terephthalate)
mixed with 2 wt % polystyrene, both from Example 1, were separately
dried in a vacuum oven for at least 16 hours at 120.degree. C. The
dried pellets were removed from the oven and quickly dropped into
separate, nitrogen blanketed supply hoppers maintained at room
temperature. The pellets were fed from the hoppers to two twin
screw remelters operated at maximum temperatures of 275.degree. C.
for the mixture of polystyrene with poly(ethylene terephthalate)
and 245.degree. C. for the mixture of polystyrene with
poly(trimethylene terephthalate) and then to a spin pack operated
at 265.degree. C.
[0048] The mixtures were spun at a 50/50 weight ratio into a quench
chamber as shown in FIG. 1. At this point the filaments of Samples
1, 2, and 3 especially, but also those of Samples 4 and 5, were
judged to be partially oriented. The filaments were then passed
through a roll system as shown in FIG. 2. Draw rolls 14 were heated
to 90.degree. C., and heat-treatment rolls 15 were heated to
150.degree. C.
[0049] The resulting fully-drawn filaments had tenacities in the
range of 2.5 to 4.4 g/denier (2.2 to 3.9 dN/tex) and
elongations-at-break in the range of 12 to 22%, with no particular
relationship to spinning speed. The relationship between windup
speed ("WUS") and after-heat-set crimp values are shown in Table I
and FIG. 3, in which the `diamonds` represent the data from Table
I. Sample 1 was spun at a withdrawal speed of about 645 m/min.
2 TABLE 1 WUS, Sample m/min CCa, % Draw Ratio 1 2515 49 3.9 2 3015
51 3.7 3 3520 48 3.5 4 4020 54 3.3 5 4520 55 3.2 6 4550 53 3.2 7
5025 40 3.0 8 5540 35 2.8 Comp. 1 5850 28 2.7
[0050] Data for Samples 1, 3, and 7 were average of two spins each.
Examination of the data in Table I shows that high crimp values of
the fully drawn filament were maintained up to windup speeds of
about 5800 m/min.
Example 3
[0051] Sample 5 was further subjected to the following tests. A
skein having a denier of 27,060 was prepared and hung vertically
from a stationary hook. A 50 g weight from was suspended from the
bottom end of the skein, which at this point had an effective
denier of 54,120. The weight was left in place for one-half minute,
and the length (D) of the effectively doubled skein was determined.
The 50 g weight was removed, a 4.54 kg weight was similarly hung
from the skein, and the skein's length was again determined after
one-half minute and labelled (B). The 4.54 kg weight was removed,
and the skein was placed in a forced draft oven at 180.degree. C.
for 5 minutes, after which it was removed and allowed to cool for
one minute. The skein was again hung from the hook for one-half
minute with the 50 g weight suspended from its bottom end, and its
length (E) was determined. Once again, the 50 g weight was removed,
the 4.54 kg weight was hung from the skein, and the skein's length
was determined after one-half minute and labelled (F).
3 The following calculations were made from the various lengths %
Original Bulk =100 .times. [B - D]/B % Total Bulk =100 .times. [B -
E]/B % Thermal Bulk =100 .times. [B - D]/D % Thermal Shrinkage =100
.times. [B - F]/B % Net Crimp =100 .times. [F - E]/F
[0052] Original Bulk is the percentage difference in length of a
skein of yarn in the crimped and extended state and indicates crimp
spontaneously developed during spinning. Total Bulk is Original
Bulk plus the crimp developed by heating the yarn. Thermal Bulk is
that portion of Total Bulk which is developed by heat and is not
present in the original spun yarn. Thermal Shrinkage is the percent
difference in length of the skein in the extended state before and
after heating. Net Crimp is the percent difference in length of the
skein in the extended and the crimped state, after having been
heated.
[0053] Sample 9 was prepared by substantially the same process as
Sample 5 except that it was spun and wound up at 3990 m/min without
drawing or heat-treating, in other words as a partially oriented
filament. It was subjected to the same additional tests. These test
results for these Samples are presented in Table II.
4TABLE II Original Total Thermal Thermal Net Sample Bulk, % Bulk, %
Bulk, % Shrinkage, % Crimp, % 5 71 81 283 30 73 9 0 72 72 44 49
[0054] As the data in Table II shows, Total Bulk, Net Crimp, and
Thermal Bulk were all very high, the last especially so in the case
of fully-drawn Sample 5. For partially oriented Sample 9, the low
Original Bulk can be advantageous for downstream processing, and
the very high Net Crimp, especially, is what would be expected for
a filament spun at only about 2500 m/min.
Example 4 (Comparison)
[0055] Poly(trimethylene terephthalate) and poly(ethylene
terephthalate) (Crystar.RTM. 4415) were separately dried, melted,
and spun into filaments substantially as described in Example 2,
except that they contained no polystyrene additive, the maximum
temperatures of the remelt extruders were 260.degree. C. for the
poly(ethylene terephthalate) and 250.degree. C. for the
poly(trimethylene terephthalate), draw rolls 14 (refer to FIG. 2)
were heated to 120.degree. C., and heat-treatment rolls 15 were
heated to 140.degree. C.
[0056] Filament tenacities were in the range of 4.1 to 4.7 g/denier
(3.6 to 4.1 dN/tex), and elongations-at-break were in the range of
11 to 25%. The relationship between windup speed ("WUS") and
after-heat-set crimp values ("CCa) are shown in Table III and FIG.
3, in which the squares represent the data from Table III.
5 TABLE III WUS, Sample m/min CCa, % Draw Ratio Comp. 2 2500 50 3.8
Comp. 3 2800 48 3.8 Comp. 4 3200 48 3.4 Comp. 5 3800 49 2.6 Comp. 6
4100 41 2.1 Comp. 7 4475 34 1.8 Comp. 8 4965 23 1.5
[0057] Data for Comparison Sample 2 were an average of two spins.
Comparison of the data in Tables I and III shows that crimp values
of the fully drawn filaments began to differ significantly at
windup speeds of about 4100 m/min, at which speed the filaments
containing polystyrene had over 30% higher crimp values than did
the filaments without polystyrene additive. The difference
increased as windup speeds increased. Further, at comparable crimp
values, the windup speeds in Table I were demonstrated to be about
1000 m/min higher than those in Table III, a significant and
unexpected advantage.
* * * * *