Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
POLY(TRIMETHYLENE ARYLATE) FIBERS, PROCESS FOR
PREPARING, AND FABRIC PREPARED THEREFROM
FIELD OF THE INVENTION
This invention relates to a process for spinning
poly(trimethylene arylate) fibers, the resultant fibers, and their use.
BACKGROUND
Poly(trimethylene arylate), particularly poly(trimethylene
terephthalate) (also referred to as 3GT, Triexta or PTT), has recently
received much attention as a fiber-forming polymer useful in textiles. PTT
fibers have excellent physical and chemical properties. Continuous
textured polyester yarns, prepared from partially oriented polyester yarns
(POY) or spun drawn yarns (SDY), mostly polyethylene terephthalate
(PET), are in wide-spread commercial use in many textile applications,
such as knit and woven fabrics, as well as non-woven fabrics, such as
spunbonded PET. The textile term "yarn" refers to a bundle of individual
fibers. For example, shirts and blouses are often made from yarns made
up of bundles of 30-40 filaments.
Polyester yarns, including both PET and PTT yarns, are
prepared by a so-called melt spinning process, and are said to be "melt
spun." Melt spinning is a process whereby the polymer is melted and
extruded through a hole in a so-called spinneret. In typical textile
applications, the spinneret is provided with a plurality of holes, often 30 ¨
40, each about 0.25 mm in diameter. Multiple filaments are thereby
extruded from a single spinneret. Those filaments are combined to form a
bundle that is called a yarn.
Polyester yarns can be used in any combinations with or
without other types of yarns. Thus, polyester yarns can make up an entire
fabric, or constitute the warp, weft or fill, in a woven fabric; or as one of
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two or more yarns in a yarn blend, for instance, with cotton, wool, rayon,
acetate, other polyesters, spandex and/or combinations thereof.
Fujimoto et al., U.S. Pat. 6,284,370, discloses a process for
preparing 1-2 dpf PTT fibers wherein a first roll is heated to 30-80 C, a
second roll is heated to 100-160 C, and the draw ratio imposed between
the first and second rolls was is in the range of 1.3-4. In 13 examples and
11 counterexamples, Fujimoto never heated the first roll to a temperature
above 60 C except in one counterexample. In all the example, the first
roll temperature was in the range of 50-60 C.
Ding, U.S. Pat. 7,785,507, discloses a process for preparing
2-3 dpf PTT fibers wherein a first godet is heated to 85-160 C, a second
godet is heated to 125-195 C, and the draw ratio imposed between the
first and second rolls was in the range of 1.1-2. Ding teaches that a first
godet temperature of 75 C caused excessive line breaks. Uster results
were ca. 0.90-0.95%. In all the examples, the temperature of the first
godet was 90 C or more.
Howell et al., U.S. Pat. 6,287,688, describes preparation of
textured PTT yarns that exhibit increased stretch, luxurious bulk and
improved hand, as compared to PET yarns. Howell et al. describes
preparing partially oriented PTT yarns at spinning speeds up to 2600 m/m.
By contrast, PET is routinely melt spun at several times that speed. For
reasons of cost, it is highly desirable to be able to spin PTT yarns at
speeds higher than 2600 m/min.
Chang et al., U.S. Patent 6,923,925, discloses a composition
comprising PTT containing about 2% polystyrene (PS) that can be melt
spun into spun drawn yarns at speeds up to 5000 m/min. Chang et al. is
completely silent in regard to the denier uniformity (Denier CV) of the
yarns so produced, and silent as well regarding the temperatures of the
godet rolls employed for preparing the spun drawn yarn.
There is a need for a low denier spun-drawn filament yarn of
PTT that can be spun at commercially viable spinning speeds and that is
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of sufficient denier uniformity to have practical utility in the preparation
of
high quality fabrics and garments.
SUMMARY OF THE INVENTION
In a first aspect, the present invention provides a filament
comprising a composition comprising 0.1 to 3% by weight of polystyrene,
based on the total weight of the polymer in the composition, dispersed in
poly(trimethylene arylate) wherein the filament is characterized by a
denier per filament of 3, a denier coefficient of variation of 2.5 % and a
birefringence of at least 0.055.
In one embodiment, the poly(trimethylene arylate) is
poly(trimethylene terephthalate).
In another aspect, the present invention provides a process
for forming a novel spun drawn filament characterized by a denier per
filament of 3, and a denier coefficient of variation of 2.5, the process
comprising extruding a polymer melt comprising 0.1 to 3 % by weight,
based on the total weight of polymer, of polystyrene dispersed in
poly(trimethylene arylate), through an orifice having a cross-sectional
shape, thereby forming a continuous filamentary extrudate, quenching the
extrudate to solidify it into a continuous filament, wrapping the filament on
a first driven roll heated to a temperature in the range of 70 to 100 C and
rotating at a first rotational speed, followed by wrapping the filament on a
second driven roll heated to a temperature in the range of 100 to 130 C
and rotating at a second rotational speed; and, winding said filament onto
a take-up roll at a linear speed of at least 4,000 meters/minute (m/min);
wherein the ratio of the first rotational speed to the second rotational
speed lies in the range of 1.75 to 3; thereby forming a spun drawn filament
having a denier per filament of 3, and a denier coefficient of variation of
2.5 %.
In one embodiment, the poly(trimethylene arylate) is
poly(trimethylene terephthalate).
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In another aspect, the present invention provides a fabric
comprising a filament comprising a composition comprising 0.1 to 3% by
weight of polystyrene, based on the total weight of the polymer in the
composition, dispersed in poly(trimethylene arylate) wherein the filament is
characterized by a denier per filament of 3, a denier coefficient of
variation of 2.5 % and a birefringence of at least 0.055.
In one embodiment, the poly(trimethylene arylate) is
poly(trimethylene terephthalate).
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a schematic representation of one embodiment of
melt feeding a spinneret according to the invention.
Figure 2 is a schematic representation of one embodiment of
the fiber spinning process according to the invention.
Figure 3 depicts a loom suitable for fabricating a woven
fabric of the invention.
Figure 4 is a schematic representation of the spinning
machines employed in the Examples.
Figure 5 is a graph of the experimental results, showing the
effect of the temperature of the first godet on the denier coefficient of
variation, and contrasting the results obtained using Spinning Machine #2
with those obtained using Spinning Machine #1.
DETAILED DESCRIPTION OF THE INVENTION
In one aspect, the present invention is directed to a filament
comprising a composition comprising 0.1 to 3% by weight of polystyrene,
based on the total weight of the polymer in the composition, dispersed in
poly(trimethylene arylate) wherein the filament is characterized by a
denier per filament (dpf) of 3, a denier coefficient of variation (denier CV)
of 2.5 % and a birefringence of at least 0.055.
In one embodiment, the poly(trimethylene arylate) is
poly(trimethylene terephthalate).
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In one embodiment, the filament hereof is a continuous
filament. In an alternative embodiment, the filament hereof is a staple
filament. In one embodiment, a plurality of the filaments hereof are
combined to form a multifilament yarn. The multifilament yarn thus formed
The multifilament yarn hereof is useful for forming knitted,
woven, and non-woven fabrics by methods known in the art.
In an alternative embodiment, the filament hereof is also
suitable for use in a wide variety of non-woven constructions. The filament
hereof can be arrayed in a random or quasi-random web to form a
filamentary non-woven fabric. In a further embodiment, the filamentary
non-woven fabric comprises a plurality of continuous filament strands
quasi-randomly disposed filament segment rather than a multi-filament
yarn segment.
In another aspect, the present invention provides a process
for forming a novel spun drawn filament characterized by a denier per
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second driven roll heated to a temperature in the range of 100 to 130 C
and rotating at a second rotational speed; and, winding said filament onto
a take-up roll at a linear speed of at least 4,000 meters/minute (m/min);
wherein the ratio of the first rotational speed to the second rotational
speed lies in the range of 1.75 to 3.
As demonstrated in the examples presented infra, the denier
CV of yarns of 3dpf when spun at speeds of 4,000 m/min or more when
the first godet is set above 70 C is conspicuously lower than that of yarns
of comparable composition spun at the same speeds when the first godet
is set at the commercially typical temperature of 60 C.
The term "denier coefficient of variation" (denier CV) refers to
the coefficient of variation in denier determined by a Uster Yarn Evenness
tester available from Uster Technologies. The so called "Uster Tester"
measures denier variation along the length of a single continuous strand of
fiber or yarn. The denier CV is a standard statistical parameter that
represents the value obtained by dividing the standard deviation of the
denier by the mean denier, determined from the Uster Tester.
In the present invention concentrations are stated in terms of
percentages by weight unless otherwise stated. In particular, it shall be
understood that the concentration of polystyrene blended with the
poly(trimethylene terephthalate) or other poly(trimethylene arylate) hereof
is expressed as the percent by weight of polystyrene relative to the total
weight of polymer in the composition.
When a range of numerical values is provided herein, it shall
be understood to encompass the end-points of the range unless
specifically stated otherwise. Numerical values are to be understood to
have the precision of the number of significant figures provided as
described in ASTM E29-08. For example, the number 3 shall be
understood to encompass a range from 2.5 to 3.4, whereas the number
3.0 shall be understood to encompass a range from 2.95 to 3.04.
For the purposes of the present invention, the description
shall be directed at those embodiments in which the poly(trimethylene
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arylate) is poly(trimethylene terephthalate) (PTT) unless otherwise
explicitly stated. Extension of the invention to other poly(trimethylene
arylates) shall be made with adjustments in concentration by weight
appropriate to differences in the molecular weight of the particular arylate
monomer units involved, assuming equal degrees of polymerization.
Both homopolymers and copolymers of both polystyrene and
PTT are suitable for use in the present invention. For the purposes of the
present invention, it shall be understood that the term "copolymer"
encompasses not only dipolymers, but terpolymers, tetrapolymers and so
forth. The term "copolymer" shall be understood to encompass any
number of monomers polymerized together. For practical purposes, the
vast majority of applications are limited to homopolymers, dipolymers, and
terpolymers.
In one embodiment, the filament comprises a composition
comprising 97 to 99.9 wt% of PTT and 3 to 0.1 wt% polystyrene (PS). In
another embodiment, the filament comprises a composition comprising 70
to 99.5 wt% of PTT, 3 to 0.5 wt% of PS, and, optionally, up to 29.5 wt% of
other polyesters. In another embodiment, the filament comprises a
composition comprising 98 to 99.5 wt% of PTT and 2 to 0.5 wt% PS.
In one embodiment, the filament consists essentially of a
composition consisting essentially of 97 to 99.9 wt% of PTT and 3 to 0.1
wt% polystyrene (PS). In another embodiment, the filament consists
essentially of a composition consisting essentially of 70 to 99.5 wt% of
PTT, 3 to 0.5 wt% of PS and, optionally, up to 29.5 wt% of other
polyesters. In another embodiment, the filament consists essentially of a
composition consisting essentially of 98 to 99.5 wt% of PTT and 2 to 0.5
wt% PS.
Suitable PTT polymer is formed by the condensation
polymerization of 1, 3-propanediol and terephthalic acid or
dimethylterephthalate. One or more suitable comonomers for
copolymerization therewith is selected from the group consisting of linear,
cyclic, and branched aliphatic dicarboxylic acids or esters having 4-12
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carbon atoms (for example butanedioic acid, pentanedioic acid,
hexanedioic acid, dodecanedioic acid, and 1,4-cyclohexanedicarboxylic
acid, and their corresponding esters); aromatic dicarboxylic acids or esters
other than terephthalic acid or ester and having 8-12 carbon atoms (for
example isophthalic acid and 2,6-naphthalenedicarboxylic acid); linear,
cyclic, and branched aliphatic diols having 2-8 carbon atoms (other than
1,3-propanediol) for example, ethanediol, 1,2-propanediol, 1,4-butanediol,
3-methyl-1,5-pentanediol, 2,2-dimethy1-1,3-propanediol, 2-methyl-1,3-
propanediol, and 1,4-cyclohexanediol; and aliphatic and aromatic ether
glycols having 4-10 carbon atoms, for example, hydroquinone bis(2-
hydroxyethyl) ether, or a poly (ethylene ether) glycol having a molecular
weight below 460, including diethyleneether glycol. The comonomer
typically is present in the PTT copolymer at a level in the range of 0.5- 15
mole %, and can be present in amounts up to 30 mole %.
The PTT can contain minor amounts of other comonomers
selected so that they do not have a significant adverse affect on
properties. Such other comonomers include 5-sodium-sulfoisophthalate,
for example, at a level in the range of 0.2 to 5 mole %. Very small
amounts of trifunctional comonomers, for example trimellitic acid, can be
incorporated for viscosity control. The PTT can be blended with up to 30
mole percent of other polymers. Examples are polyesters prepared from
other diols, such as those recited supra.
In one embodiment, the PTT contains at least 85 mol-% of
trimethylene terephthalate repeat units. In a further embodiment, the PTT
contains at least 90 mol-`)/0 of trimethylene terephthalate repeat units. In a
still further embodiment the PTT contains at least 98 mol- "Yo of of
trimethylene terephthalate repeat units. In a still further embodiment the
PTT contains 100 mol (:)/0 of trimethylene terephthalate repeat units.
In one embodiment, suitable PTT is characterized by an
intrinsic viscosity (IV) in the range of 0.70 to 2.0 dl/g. In a further
embodiment, suitable PTT is characterized by an IV in the range of 0.80 to
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1.5 dl/g. In a still further embodiment, suitable PTT is characterized by an
IV in the range of 0.90 to 1.2 dl/g.
In one embodiment, suitable PTT is characterized by a
number average molecular weight (Me) in the range of 10,000 to 40,000
Da. In a further embodiment suitable PTT is characterized by Me in the
range of 20,000 to 25,000 Da.
In one embodiment, a suitable polystyrene is selected from
the group consisting of polystyrene homopolymer, a-methyl-polystyrene,
and styrene-butadiene copolymers, and blends thereof. In one
embodiment, the polystyrene is a polystyrene homopolymer. In a further
embodiment, the polystyrene homopolymer is characterized by Me in the
range of 5,000 to 300,000 Da. In a still further embodiment, Me of the
polystyrene homopolymer is in the range of 50,000 to 200,000 Da. In a
still further embodiment Me of the polystyrene homopolymer is in the range
of 75,000 to 200,000 Da. In a still further embodiment, Me of the
polystyrene homopolymer is in the range of 120,000 to 150,000 Da. Useful
polystyrenes can be isotactic, atactic, or syndiotactic. High molecular
weight atactic polystyrene homopolymer is preferred.
Polystyrenes useful in this invention are commercially
available from many suppliers including Dow Chemical Co. (Midland,
Mich.), BASF (Mount Olive, N.J.) and Sigma-Aldrich (Saint Louis, Mo.).
PTT and PS are melt blended and, then, extruded in the
form of a strand that is subsequently cut into pellets. Other forms of melt
blending and subsequent comminution, such as into flake, chips, or
powder, can also be performed. Under some circumstances it may be
convenient to prepare pellets comprising a first PTT/PS blend with a
concentration of PS greater than 15% followeb by remelting the pellets
and diluting the remelt with additional PTT to form a second melt blend
having a concentration of PS that is 3 (Yo, and to extrude the second melt
blend into the filament hereof.
The filament hereof comprises a composition comprising
PTT and PS. In some embodiments, these will be the only two materials
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in the blend and they will total 100 weight %. However, in many instances
the blend will have other ingredients such as are commonly included in
polyester polymer compositions in commercial use. Such additives
include but are not limited to other polymers, plasticizers, UV absorbers,
flame retardants, dyestuffs, and so on. Thus the total of the
poly(trimethylene terephthalate) and polystyrene will not be 100 weight %.
Other polymers can include for example polyam ides that impart acid
dyeability to the yarn blend. In those instances in which additional, non-
polyester, polymers are added, the ratios of polyester to PS weight
percent concentrations remain the same as for those compositions that do
not include the other polymers.
According to the present invention, the PS is in the form of
particles having an average size of less than 500 nanometers. In one
embodiment, the polystyrene is polystyrene homopolymer at a
concentration of 2%; and, the poly (trimethylene arylate) is PTT
comprising at least 98 mol% of trimethylene terephthalate monomer units.
The filament of the present invention is characterized by a
dpf 3, a denier CV of 2.5 %, and a birefringence of at least 0.055.
Typical physical properties of the filament hereof include a tenacity above
3 grams per denier, and an elongation to break of 30 to 70%. In one
embodiment, the filament denier is 2.5. In another embodiment, the
birefringence is at least 0.060.
In another aspect, this invention is directed to a process for
preparing a single or multifilament yarn comprising (a) preparing a melt
blend consisting essentially of PTT and 0.1 to 3 weight (:)/0 (wt%)
polystyrene (PS), (b) melt spinning the polymer melt blend so prepared to
form one or more filaments of PTT containing dispersed PS.
The filament of the present invention is conveniently
prepared as a spun drawn filament ¨ that is, a filament that has been fully
drawn in the spinning process. By fully drawn is meant that the filament
after quenching has been elongated close to the ultimate elongation to
break thereof. Preferably, the spinning comprises extruding the polymer
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blend hereof through the one or more holes of a spinneret at a spinning
speed of at least 4,000 m/m. The term "spinning speed" refers to the rate
of spun fiber accumulation, such as on a mechanical wind-up.
The high birefringence of 0.055 that is characteristic of the
filament of the invention is a direct result of the high draw applied to the
filament in the spun-draw process. High birefringence is a principle way of
distinguishing spun-drawn filaments from partially-oriented spun yarn that
is subsequently draw-textured.
Figure 1 is a schematic representation of one embodiment of
a melt spinning machine suitable for use in the present invention.
Referring to Figure 1, PTT is produced in a continuous melt polymerizer,
1, from which it is conveyed in molten form via transfer line, 2, to a
counter-rotating twin-screw extruder, 3, the twin screw extruder being
provided with a mixing zone. Simultaneously, pellets comprising PS are
fed via a weight-loss feeder, 4, or other pellet feeder means, to a satellite
extruder, 5, wherein the pellet is melted and fed in molten form via transfer
line, 6, to twin-screw extruder,3, either at or upstream from the mixing
zone of the twin-screw extruder, 3. In the twin-screw extruder a PTT/PS
melt blend is formed. The resulting melt blend is fed via transfer line, 7, to
a spin block comprising a spinneret, 8, from which one or more continuous
filaments, 9, are extruded.
Figure 2 depicts one suitable arrangement for melt spinning
according to the invention. 34 filaments 22, (all 34 filaments are not
shown) are extruded through a hole spinneret 21. The filaments pass
through a cooling zone 23, are formed into a yarn bundle, and passed
over a finish applicator 24. The cooling zone comprises an air quench
zone wherein air is impinged upon the yarn bundle at room temperature
and at 60% relative humidity with a velocity of 40 feet/min. The air quench
zone can be designed for so-called cross-air-quench wherein the air flows
across the yarn bundle, or for so-called radial quench wherein the air
source is in the middle of the converging filaments and flows radially
outward over 360 0. Radial quench is a more uniform and effective
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quench method. Following the finish applicator 24, the yarn is passed to a
first driven godet roll 25, also known as a feed roll, set at 60 to 100 C, in
one embodiment, 70 to 100 C, coupled with a separator roll. The yarn is
wrapped around the first godet roll and separator roll 6 to 8 times. From
the first godet roll, the yarn is passed to a second driven godet roll, also
known as a draw roll, set at 110 to 130 C, coupled with a second
separator roll. The yarn is wrapped around the second godet roll and
separator roll 6 to 8 times. Draw roll speed is 4000 to 6000 m/min while
the ratio of draw roll speed to feed roll speed is in the range of 1.75 to 3.
From the draw rolls, the yarn is passed to a third driven godet roll 27,
coupled with a third separator roll, operated at room temperature and at a
speed 1-2% faster than the roll speed of the second godet roll. The yarn
is wrapped around the third pair of rolls 6 to 10 times. From the third pair
of rolls, the yarn is passed though an interlace jet 28, and then to a wind-
up 29, operated at a speed to match the output of the third pair of rolls.
Referring to Figure 2, according to the process hereof, a
quenched filament is wound at least once but preferably a plurality of
times around the first godet roll so that the first godet roll applies a
drawing
force on the extruded filament, causing it to draw down before quenching;
down stream from the first godet roll, the filament is wrapped at least once
but preferably a plurality of times around a second godet roll in such
manner that the second godet applies a drawing force on that portion of
the filament lying between the first and second godet rolls. In the
embodiment depicted in Figure 2, from the second godet roll, the filament
is directed to a third godet roll which serves as a let down roll, running at
a
speed 1-2% higher than that of the second (draw) godet roll. From the
third godet, the filament is directed to a wind-up. The rate at which the
filament is wound on the wind-up is described as the spinning speed. In
typical installations, the wind-up is a tension controlled wind-up.
According to the present invention, the first godet roll is
heated to a temperature in the range of 70-100 C and the second godet
roll is heated to a temperature in the range of 100 ¨ 130 C. The first
godet roll is driven at a first rotational speed; the second godet roll is
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driven at a second rotational speed. According to the present invention
the ratio of the second rotational speed to the first rotational speed (the
draw ratio) falls within the range of 1.75 to 3.
In one embodiment, a plurality of filaments, each individually
of the invention, are extruded through a multi-hole spinneret. The
filaments so extruded are combined to form a yarn. Typically the yarn is
held together by the application of some agitation, twisting, or both, of the
extruded filaments, or thread line, causing the interlacing of the filaments.
The yarn so formed comprises a plurality of filaments, each filament
characterized by a dpf 3, a denier CV of 2.5 %, and a birefringence of
at least 0.055. In one embodiment, the filament denier is 2.5. In another
embodiment, the birefringence is at least 0.060. Typical yarns comprise
34, 48, 68, and 72 filaments, although the number of filaments combined
to make a yarn is not limited in any way.
Yarns formed according to the present invention are not
limited only to be made up of a plurality of filaments according to the
invention, but can contain other filaments as well. For example, a yarn
formed according to the invention can contain other filaments of other
polyesters as well as polyam ides, polyacrylates and other such filaments
as may be desired. The other filaments can also be staple fibers.
The yarn formed according to the invention, which can be
formed by the spun-draw process described supra, is suitable for use as a
feed yarn for false twist texturing as commonly practiced in order to
provide textile-like aesthetics to continuous polyester fibers. While there
are several types of texturing equipment, all well-known in the art, the
texturing process comprises a) providing a yarn package as formed
according to the spinning process described supra; (b)unwinding the yarn
from the package, (c) threading the yarn end through a friction twisting
element or false-twist spindle, d) causing the spindle to rotate, thereby
imparting twist in the yarn upstream of the rotating spindle and untwisting
the upstream twist downstream from the rotating spindle along with the
application of heat; and (e) winding the yarn onto a package.
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The invention enables an increase in productivity in the
spinning of fine denier 3 dpf) spun ¨ drawn PTT yarns. The filament
and yarn thereof of the invention have been prepared at spinning speeds
that are 30 to 70 % higher than the maximum spinning speed achievable
with neat PTT. The resulting yarn is characterized by an elongation and
tenacity within 20% of the elongation and tenacity of a PTT multifilament
yarn that only differs from the yarn of the invention in that it does not
contain the PS (and that has necessarily been spun at about 3000 m/min).
Thus, the yarns consisting essentially of the filaments of the invention are
useful in a wide variety of textile applications with only minor adjustments
needed in the textile machinery being used. The resultant yarns are
useful in preparing inter alia textured yarns, fabrics and carpets, under the
same or similar conditions to those used for PTT yarns not containing PS
and prepared at 3000 m/min.
In the filament of the invention, the PTT is a continuous
phase or "matrix" and the PS is a discontinuous phase dispersed within
the PTT matrix. In one embodiment, the size of the PS particles dispersed
in the PTT matrix is 500 nm. In a further embodiment, the size of the PS
particles dispersed in the PTT matrix is 200 nm.
The beneficial features of the present invention include the
ability to spin a fine denier, high strength, tough, spun drawn PTT yarn at
spinning speeds of 4000 m/min or higher. These beneficial features
depend upon both the fine particle size of PS and the volume homogeneity
of the dispersion of PS in the PTT that in turn depend upon the application
of sufficiently high shear melt blending. There is no threshold particle size
at which the spinning performance and/or physical properties of the spun
yarn suddenly degrades. Rather, as the PS particle size gets larger,
performance gradually deteriorates. At particle sizes in the range of 500
nm or larger, denier CV gets progressively larger. Similarly, there is no
particular threshold of homogeneity in regard to particle distribution in the
PTT matrix. The better the uniformity of dispersion, the more uniform the
resulting spun filament will be. One particularly valuable benefit of the
present invention is the production of spun-drawn yarns characterized by
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denier CV of less than 2.5 (Yo. Low denier CV is especially important in the
preparation of fine denier yarns for textile applications. Unless the
process by which the PS is dispersed in PTT is characterized by shear
forces sufficient to ensure a particle size less than 500 nm and a
The amount of shear force applied to the melt depends upon
the rotational speed of the mixing elements, the viscosity of the melt, and
the residence time of the melt in the mixing zone. If the shear forces are
The melt blending process can be performed both batch-
wise and continuously. So called high shear mixers such as are
commonly employed in the art of polymer compounding are suitable.
30 Average particle size greater than 500 nm is not preferred
from the standpoint of good fiber spinning performance. Additionally,
spinning of uniform filaments, both along a single end, and end to end,
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depends expressly upon the homogeneity of the volume distribution of the
PS particles. While in no way limiting the scope of the invention, it is
speculated that in the actual melt processing thereof, the PS particles melt
to form molten droplets that are dispersed within a molten PTT matrix.
The temperature in the melt mixer should be above the
melting points of both the PTT and the PS but below the lowest
decomposition temperature of any of the ingredients. Specific
temperatures will depend upon the particular attributes of the polymers
employed. In typical practice, melt temperature is in the range of 200 C
to 270 C.
In one embodiment, the concentration of the PS in the
PTT/PS blend pellets is in the range of 0.5 to 1.5 (Yo.
As indicated in Figure 1, and as is generally true for melt
spinning of polymer fibers, the polymer melt is fed to the spinneret via a
transfer line. The melt input to the transfer line from the extruder is in
turbulent. However, the spinneret feed must be laminar in order to
achieve uniform flow through the plurality of holes in the spinneret. It is in
the transfer line that the melt flow shifts from turbulent to laminar.
Filament spinning can be accomplished using conventional
apparatus and procedures that are in widespread commercial use. As a
practical matter, it is found that for spinning fine denier filaments of 3 dpf
or lower, a PS concentration of > 3% leads to a degradation in mechanical
properties of the fiber so produced. It is further found that at 5% PS, fine
denier filaments cannot be melt spun at all.
Prior to melt spinning, the polymer blend pellets are
preferably dried to a moisture level of <30 ppm to avoid hydrolytic
degradation during melt spinning. Any means for drying known in the art is
satisfactory. In one embodiment, a closed loop hot air dryer is employed.
Typically, the PTT/PS blend is dried at 130 C and a dew point of <-40 C
for 6 h. The thus dried PTT/PS polymer blend is melt spun at 250-265 C
into fibers.
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In a typical melt spinning process, one embodiment of which
is described in detail, infra, the dried polymer blend pellets are fed to an
extruder which melts the pellets and supplies the resulting melt to a
metering pump, which delivers a volumetrically controlled flow of polymer
into a heated spinning pack via a transfer line. The pump must provide a
pressure of 10-20 MPa to force the flow through the spinning pack, which
contains filtration media (eg, a sand bed and a filter screen) to remove any
particles larger than a few micrometers. The mass flow rate through the
spinneret is controlled by the metering pump. At the bottom of the pack,
the polymer exits into an air quench zone through a plurality of small holes
in a thick plate of metal (the spinneret). While the number of holes and the
dimensions thereof can vary greatly, typically a single spinneret hole has a
diameter in the range of 0.2¨ 0.4 mm. Spinning is advantageously
accomplished at a spinneret temperature of 235 to 295 C, preferably 250
to 290 C.
A typical flow rate through a hole of that size tends to be in
the range of 1-5 g/min. Numerous cross-sectional shapes are employed
for spinneret holes, although circular cross-section is most common.
Typically a highly controlled rotating roll system through which the spun
filaments are wound controls the line speed. The diameter of the filaments
is determined by the flow rate and the take-up speed; and not by the
spinneret hole size.
The properties of the thus produced filaments are
determined by the threadline dynamics, particularly in the region between
the exit from the spinneret and the solidification point of the filaments,
which is known as the quench zone. The specific design of the quench
zone, air flow rate across the emerging still motile filaments has very large
effects on the quenched filament properties. Both cross-flow quench and
radial quench are in common use. After quenching or solidification, the
filaments travel at the take-up speed, that is typically 100-200 times faster
than the exit speed from the spinneret hole. Thus, considerable
acceleration (and stretching) of the threadline occurs after emergence
from the spinneret hole. The amount of orientation that is frozen into the
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spun filament is directly related to the stress level in the filament at the
solidification point.
The melt spun filament thereby produced is collected in a
manner consistent with the desired end-use. For example, for filament
intended to be converted into staple fiber, a plurality of continuous
filaments can be combined into a tow that is accumulated in a so-called
piddling can. Filament intended for use in continuous form, such as in
texturing, is typically wound on a yarn package mounted on a tension-
controlled wind-up. According to the invention, the rate of accumulation is
at least 4,000 m/min.
Texturing imparts crimp by twisting, heat setting, and
untwisting by the process commonly known as false twist texturing. These
multifilament yarns (also known as "bundles") comprise the same number
of filaments as the spun drawn yarns from which they are made. Thus,
they preferably comprise at least 10 and even more preferably at least 25
filaments, and typically can contain up to 150 or more, preferably up to
100, more preferably up to 80 filaments. The yarns typically have a total
denier of at least 1, more preferably at least 20, preferably t least 50, more
preferably up to 250, and up to 1,500. Filaments are preferably at least
0.1 dpf, more preferably at least 0.5 dpf, more preferably at least 0.8 dpf,
and most preferably up to 3 dpf.
PTT staple fibers can be prepared by melt spinning the
PTT/PS- blend at a temperature of 245 to 285 C. into filaments,
quenching the filaments, drawing the quenched filaments, crimping the
drawn filaments, and cutting the filaments into staple fibers, preferably
having a length of 0.2 to 6 inches (0.5 to 15 cm). One preferred process
comprises: (a) providing a polymer blend comprising PTT and 0.1 to 3 (:)/0
PS, (b) melt spinning the melted blend at a temperature of 245 to 285 C.
into filaments, (c) quenching the filaments, (d) drawing the quenched
filaments, (e) crimping the drawn filaments using a mechanical crimper at
a crimp level of 8 to 30 crimps per inch (3 to 12 crimps/cm), (f) relaxing the
crimped filaments at a temperature of 50 to 120 c., and (g) cutting the
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relaxed filaments into staple fibers, preferably having a length of 0.2 to 6
inches (0.5 to 15 cm). In one preferred embodiment of this process, the
drawn filaments are annealed at 85 to 115 C. before crimping.
Preferably, annealing is carried out under tension using heated rollers. In
another preferred embodiment, the drawn filaments are not annealed
before crimping. Staple fibers are useful in preparing textile yarns and
textile or nonwoven fabrics, and can also be used for fiberfill applications
and making carpets.
While the invention is primarily described with respect to
multifilament yarns, it should be understood that the preferences
described herein are applicable to monofilaments.
The filaments can be round or have other shapes, such as
octalobal, delta, sunburst (also known as sol), scalloped oval, trilobal,
tetra-channel (also known as quatra-channel), scalloped ribbon, ribbon,
starburst, etc. They can be solid, hollow or multi-hollow.
In another aspect, the invention provides a fabric comprising
a filament comprising a composition comprising 0.1 to 3% by weight of
polystyrene, based on the total weight of the polymer in the composition,
dispersed in poly(trimethylene arylate) wherein the filament is
characterized by a denier per filament of 3, a denier coefficient of
variation of 2.5 % and a birefringence of at least 0.055. In one
embodiment, the poly(trimethylene arylate) is poly(trimethylene
terephthalate).
In one embodiment the filaments are bundled into yarns, and
the fabric is a woven fabric. In an alternative embodiment, the filaments
are bundled into at least one yarn, and the fabric is a knit fabric. In still
another embodiment, the fabric is a nonwoven fabric; in a further
embodiment the fabric is a spunbonded fabric.
In one definition, a nonwoven fabric is a fabric that is neither
woven nor knit. Woven and knit structures are characterized by a regular
pattern of interlocking yarns produced either by interlacing (wovens) or
looping (knits). In both cases, yarns follow a regular pattern that takes
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them from one side of the fabric to the other and back, over and over
again. The integrity of a woven or knitted fabric is created by the structure
of the fabric itself.
In nonwovens, most commonly filaments are laid down in a
random pattern and bonded to one another by chemical or thermal means
rather than mechanical means. One commercially available example of a
nonwoven produced by such means is Sontara Spun-Bonded Polyester
available from the DuPont Company. In some cases nonwovens can be
produced by laying down layers of fibers in a complex three dimensional
topological array that does not involve interlacing or looping and in which
the fibers do not alternate from one side to the other, as described in
Popper et al., U.S. Patent 6,579,815.
Woven fabrics are made with a plurality of yarns interlaced at
right angles to each other. The yarns parallel to the length of the fabric
are called the "warp" and the yarns orthogonal to that direction are called
the "filling" or "weft." Each warp yarn is called an "end." As can be seen in
any fabric or clothing store, tremendous variations in aesthetics can be
achieved by variations in the specific ways the yarns are interlaced, the
denier of the yarns, the aesthetics, both tactile and visual, of the yarns
themselves, the yarn density, and the ratio of warp to filling yarns. As a
general rule, the structure of a woven fabric imparts a certain degree of
rigidity to the fabric; a woven fabric does not in general stretch as much as
a knitted fabric.
In the woven fabrics of the invention, at least a portion of the
warp comprises yarns comprising a filament comprising a composition
comprising 0.1 to 3% by weight of polystyrene, based on the total weight
of the polymer in the composition, dispersed in poly(trimethylene arylate)
wherein the filament is characterized by a denier per filament of 3, a
denier coefficient of variation of 2.5 % and a birefringence of at least
0.055. In one embodiment, the poly(trimethylene arylate) is
poly(trimethylene terephthalate).
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In one embodiment, both the warp and fill comprise yarns
comprising the filament hereof. In one embodiment, the warp comprises
at least 40 % by number of yarns comprising the filament hereof and at
least 40 % by number of cotton yarns. In one embodiment the warp
comprises at least 80% by number of yarns comprising the filament
hereof, and the fill comprises at least 80 % cotton yarn. As a general rule,
there are greater physical demands place upon warp yarns than fill yarns.
Woven fabrics are fabricated on looms, as they have been
for thousands of years. While the loom has undergone tremendous
changes, the basic principles of operation remain the same. Figure 3a is a
schematic depiction of an embodiment of a loom, shown in side view. A
warp beam, 31, made up of a plurality, often hundreds, of parallel ends,
32, is positioned as the loom feed. Warp beam, 31, is shown in front view
in Figure 3b. Shown in Figure 3a is a two harness loom. Each harness,
34a, and 34b, is a frame that holds a plurality, often hundreds, of so called
"heddles." Referring to Figure 3c, showing a front, blowup view of a
harness, 34, each heddle,311, is a vertical wire having a hole, 312, in it.
The harnesses are disposed to move up or down, one moving up while the
other moves down. A portion of the ends, 33a, are threaded through the
holes, 312, in the heddles, 311, of upper harness, 34a, while another
portion of the ends, 33b, are threaded through the holes in the heddles of
lower harness, 34b, thereby opening up a gap between the ends 33a and
33b. In the type of loom shown, a shuttlecock, 36, is impelled by means
not shown ¨ typically wooden paddles ¨ to move or shuttle from side to
side as the harnesses move up and down. The shuttlecock carries a
bobbin of filler yarn, 37, that unwinds as the shuttlecock moves through
the gap in the warp ends. A socalled "reed" or "batten," 35, is a frame that
holds a series of vertical wires between which the ends pass freely.
Figure 3d shows the reed, 35, in front view depicting the vertical wires,
313, and the spaces between, 314, through which the warp yarns pass.
The thickness of the vertical wires, 314, determines the spacing of and
therefore density of warp yarns in the crossfabric direction. The reed
serves to push the newly inserted filler yarn to the right in the diagram into
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place in the forming fabric, 38. The fabric is wound onto the fabric beam,
310. The rolls, 39, are guide rolls.
The winding of a warp beam is a precision operation in which
typically the same number of yarn packages or spools as the desired
number of ends are mounted on a so-called creel, and each end is fed
onto the warp beam through a series of precision guides and tensioners,
and then the entire warp beam is wound at once.
The specific patterns of interlacing, ratios of warp to fill yarns
determine the type of woven fabric prepared. Basic patterns include plain
weave, twill weave, and satin. Numerous other, fancier woven patterns
are also known.
Knitting is the process by which a fabric is prepared by the
interlooping of one or more yarns. Knits tend to have more stretch and
resilience than wovens. Knits tend to be less durable than wovens. As in
the case of wovens, there are many knit patterns, and styles of knitting.
According to the present invention, in one embodiment the fabric hereof is
a knit fabric comprising yarns comprising a filament comprising a
composition comprising 0.1 to 3% by weight of polystyrene, based on the
total weight of the polymer in the composition, dispersed in
poly(trimethylene arylate) wherein the filament is characterized by a
denier per filament of 3, a denier coefficient of variation of 2.5 % and a
birefringence of at least 0.055. In one embodiment, the poly(trimethylene
arylate) is poly(trimethylene terephthalate).
Further contemplated in the present invention are garments
sewn from fabrics of the invention. The garments hereof comprise a fabric
comprising yarns comprising a filament comprising a composition
comprising 0.1 to 3% by weight of polystyrene, based on the total weight
of the polymer in the composition, dispersed in poly(trimethylene arylate)
wherein the filament is characterized by a denier per filament of 3, a
denier coefficient of variation of 2.5 % and a birefringence of at least
0.055. In one embodiment, the poly(trimethylene arylate) is
poly(trimethylene terephthalate).
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The fabrication of garments from fabrics is extremely well-
known art. The preparation of a garment from a fabric includes preparing
a pattern, usually from paper, or in computerized form for automated
processes, measuring the required fabric pieces, cutting the fabric to
prepare the needed pieces, and then sewing the pieces together
according to the pattern. A garment may be made exclusively one or
more styles of the fabric of the invention. Alternatively, a garment may be
prepared by combining one or more styles of the fabric of the invention
with other fabrics.
The invention is further described in the following specific
embodiments, but is not limited thereto.
EXAMPLES
TEST METHODS
INTRINSIC VISCOSITY
The intrinsic viscosity (IV) of the PTT was determined using
a Viscotek Forced Flow Viscometer Y900 (Viscotek Corporation, Houston,
Tex.) Following the procedures of ASTM D-5225-92, a 0.4 g/d1 solution of
PTT was formed in a 50/50 weight % solvent mixture of trifluoroacetic acid
and methylene chloride at 19 C. and the viscosity determined. These
measured IV values were correlated to IV values measured manually in
60/40 weight % pheno1/1,1,2,2-tetrachloroethane following ASTM D 4603-
96.
NUMBER AVERAGE MOLECULAR WEIGHT
The number average molecular weight of polystyrene was
determined following ASTM D 5296-97. The same method was used for
poly(trimethylene terephthalate) except that the calibration standard was a
poly(ethylene terephthalate) with an Mw of 44,000 and
hexafluoroisopropanol solvent.
TENACITY AND ELONGATION AT BREAK
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The physical properties of the filaments and yarns were
measured using an Instron Corp. tensile tester, model no. 1122. More
specifically, elongation to break, Eb , and tenacity were measured
according to ASTM D-2256.
SPINNING CAMPAIGNS AND SPINNING MACHINE AFFECT ON RESULTS
Fiber spinning was performed in four separate campaigns.
As described in greater detail infra, Campaigns #1, 3, and 4 were
executed on Spinning Machine #2, while Campaign #2 was executed on
Spinning Machine #1.
The results obtained from Spinning Machine #1 were
scattered, as shown in Table 4 and Figure 5, and are not considered
definitive. In particular, the denier coefficient of variation was higher than
the limit as specified in the invention, and did not appear to vary
systematically with the temperature of the first godet
Figure 5 is a graph showing the denier CV versus first godet
temperature wherein all of the data obtained from Campaigns 1,3, and 4
are combined together and plotted with a diamond shape, and the data
from Campaign #2 is graphed using a triangle shape. As shown in Tables
3 ¨ 6, infra, not all data points obtained in the three campaigns wherein
Spinning Machine #2 was employed were obtained using the same set of
spinning conditions. Nevertheless, as seen in Figure 5, the data from
Spinning Machine #2, shown as diamond shapes, showed a clear trend,
where first godet temperature in the range of ca. 75 to 85 C corresponded
to a minimum in denier CV. A similar trend was not observed in the data
of Campaign #2.
Denier coefficient of variation is a measurement of short
distance denier variability, which is in turn, an indicator of the stability
of
the melt spinning process. The melt spinning process can be unstable
because the spinning composition causes an instability. It can also be
unstable because the machine is unstable. It is clear from Figure 5 that in
this case the high denier CV produced in Campaign #2 was an artifact of
the machine performance and design.
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Spinning Machine #1 was a laboratory-built spinning
machine provided with only the most basic equipment to effect melt
spinning. Spinning Machine #1 was employed normally only to obtain the
most basic information about whether or not experimental compositions
were capable of being melt-spun into fiber. It was employed in Campaign
#2 herein because of a scheduling mix-up ¨ Spinning Machine #2 was not
available on the day scheduled for Campaign #2. Spinning Machine #2
was a pilot plant spinning line. Conditions thereon were fully scalable to
full-size commercial scale spinning lines. This was the spinning line of
choice for demonstrating the differences in results that are characteristic of
the invention.
Figure 4 schematically depicts Spinning Machine #2. A silo
drier, 41, gravity fed a single screw extruder, 42, with dried resin blend
pellets. The output of the single screw extruder, 42, was fed directly,
under pressure, to the input of a gear pump,43, provided with an overflow
port, 44. The output of the gear pump was supplied via a short (inches
long) transfer line, 45, to a six end spin pack, 46. of which four ends were
used. Each of four threadlines, 47 (one shown), was extruded from a 36
hole spinneret, (not shown) whereof each hole was characterized by a
round cross-section of 0.27 mm diameter and 0.50 mm in length. Each
threadline, 47, passed through a cross-flow quench air zone approximately
1.75 m in length, 48, with ambient air flowing across the threadline from
one side to another in campaign 1 and a radial quench air zone
approximately 1.75 m in length, 48, with ambient air flowing radially
around the threadline to produce even more uniform filaments in
campaigns 3 and 4. Each thus quenched threadline was contacted to a
finish roll, 49, and then wrapped 6-8 times around a first heated godet
(feed roll), 410, and a corresponding first separator roll, 411, to keep the
threadlines apart. The threadline was then directed to a second heated
godet (draw roll), 412, and a second corresponding second separator roll,
413, through an interlace jet (not shown) and thence to a windup, 414.
Also not shown, each Godet was partially enclosed by a hot chest to
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maintain temperature. The extruder was provided with 3 heating zones,
and a head zone at the output.
Spinning Machine #1 and Spinning Machine #2 were
substantially the same in regard to the layout described in Figure 4. Once
difference was that the quench air chimney in Spinning Machine #1 was
much narrower than its counterpart on Spinning Machine #2.
In all the Examples and Comparative Examples, the average
results for four threadlines spun simultaneously under each set of
conditions are reported. The spinning machines were allowed to reach
steady state after a change in set-point conditions by running for ca. 45
minutes before a test sample was prepared. When the composition of the
polymer was changed, the spinning machine was purged with PTT not
containing PS. When the spinneret was changed, the machine was
purged in between spinning experiments.
PREPARATION OF POLYMER BLENDS
Samples of PS in PTT (0.8 and 0.55 wt%) were made by co-
feeding dried PTT and PS to a 30 mm T/S extruder. Sorona Semi-Dull
PTT resin pellets (1.02 IV available from the DuPont Company,
Wilmington, DE) polytrimethylene terephthalate was combined with
polystyrene (168 M KG 2 available from BASF) pellets in the amounts
shown in Table 1. The PTT was dried in a vacuum oven with a nitrogen
purge at 120 C for 14 hours prior to use. The two polymers were
individually weight-loss fed to the fourth barrel section of a Werner &
Pfleiderer ZSK-30 counter-rotating twin screw extruder. The feed rates
employed are shown in Table 1 in pounds per hour (pph). The extruder
had a 30 mm diameter barrel constructed with 13 barrel sections provided
in alternating arrangement with two kneading zones and three conveying
sections, the extruder having an LID ratio of 32. Each barrel section was
independently heated. Sections 1-4 were set at 25 C, Sections 5-13 were
set at 210 C, the 3/16" strand die was also set at 210 C. A vacuum was
applied to barrel segment 8. Table 1 also shows the composition of the
feed, the rate of output, and the melt temperature. The extrudate was
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quenched in water immediately upon exiting the die and was then
pelletized using standard pelletizing equipment into 1/8" pellets.
Table 1
PS Set PTT Set
Feed Feed Output Melt
Polymer Compostion Rate Rate Rate Temperature
Blend # (% PS) (PPh) (PPh) (PPh) ( C)
1 0.80 0.32 39.68 40.00 260
2 0.55 0.22 39.78 40.00 260
MELT SPINNING
Melt spinning of fiber was conducted in four separate spinning
campaigns as described infra. Table 2 shows the spinning parameters
that were held constant during each campaign.
Table 2: Fixed Spinning Parameters by Campaign
Campaign #: 1 2 3 4
Spinning
Machine 2 1 2 2
[PS] Variable 0.80 0.80 0.80
Capillary
Diameter (mm) 0.27 Variable 0.27 0.27
Polymer Flow
Rate (g/min) 37.5 37.5 Variable 37.5
Quench Cross-Flow Cross-Flow Radial Radial
Second Godet
Speed (rpm) 4500 4500 Variable 4500
Second Godet
Temperature ( C) 110 110 110 110
CAMPAIGN #1 ¨ SPINNING MACHINE #2
The melt compounded pellets of the PTT/PS blend so prepared were
dried in a drying silo overnight at 140 C to lower the moisture content to
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<50 ppm. The dried melt blends were gravity fed to the single screw
extruder described supra, in Figure 4, of Spinning Machine #2. Extruder
set points, in C, in zones 1-3 were respectively 230/255/263. The
extruder output was melt-fed to the spin pack through a gear pump. The
spin pack was provided with six spinning positions of which four were
provided with spinnerets each spinneret having 36 holes, each hole being
0.27 mm in diameter and 0.5 mm in length, and of circular cross-section.
Each yarn so produced was a 75 denier 36 filament yarn. The settings of
the first godet roll are shown in Table 3. Note that the second godet roll
was maintained at 11000 and 4500 rpm. The quench air was a cross-flow
quench with an air velocity of 0.35 cm/s.
The protocol that was followed was as follows: The second
godet roll (draw roll) was set at 4500 m/min and 110 C, and was not
changed in the course of the experiments. Experiments were then
conducted with the first godet roll (feed roll) set at 60 C and the speed
was varied in order to identify a draw ratio that resulted in the highest
tenacity when elongation to break was adjusted to be in the range of 55 -
65 %. For Polymer Blend #2 (0.055 "Yo PS) a draw ratio of 2.09 was found
to result in the highest tenacity when elongation to break was within the
desired range (i.e., the feed roll was set at 2150 m/min). Spinning was
then continued at additional feed roll temperatures of 85 and 110 C. The
same procedure was followed for Polymer Blend #1(0.8% PS); a draw
ratio of 2.37 was found to result in the highest tenacity when elongation to
break was within the desired range (i.e., feed roll speed=1900 m/min).
Results are shown in Table 3
Table 3: Results of Campaign #1
PS G1 G1 Draw
DPF Denier
Example conc Speed Temp Ratio
(g /9000m) CV (%)
(wt%) (m/min) ( C) (G2/G1)
Comp.Ex.A 0.80 2150 60 2.09 2.0 3.50
Comp.Ex.B 0.80 1900 60 2.37 2.0 3.19
Comp.Ex.0 0.80 1750 60 2.57 2.1 3.01
EX.1 0.80 1900 85 2.37 2.0 1.78
EX.2 0.80 1900 110 2.37 2.0 2.02
Comp.Ex.D 0.55 2300 60 1.96 2.1 2.71
Comp.Ex.E 0.55 2150 60 2.09 2.1 3.83
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Ex.3 1 0.55 2150 85 2.09 2.1 2.07
Ex.4 0.55 2150 110 2.09 2.0 2.69
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CAMPAIGN #2¨ SPINNING MACHINE #1
A new melt blend of 0.80 (:)/0 by weight in PTT identical to that of Blend
#1 supra. The melt compounded pellets of the PTT/PS blend so prepared
were dried in a drying silo overnight at 140 C to lower the moisture
content to <50 ppm. The dried melt blend pellets were gravity fed to the
single screw extruder described supra, in Figure 4, of Spinning Machine
#1. Extruder set points, in C, in zones 1-3 were respectively
230/255/263. The extruder output was melt-fed to the spin pack through a
gear pump. The spin pack was provided with six spinning positions of
which four were provided with spinnerets each spinneret having 36 holes,
each hole being 0.27 mm in diameter and 0.5 mm in length, and of circular
cross-section. Each yarn so produced was a 75 denier 36 filament yarn.
The settings of the first godet roll are shown in Table 4. Note that the
second godet roll was maintained at 110 C and 4500 rpm. The quench
air was a cross-flow quench with an air velocity of 0.35 cm/s.
The protocol that was followed was as follows: The second
godet roll (draw roll) was set at 4500 m/min and 110 C, and was not
changed in the course of the experiments. Experiments were then
conducted with the first godet roll (feed roll) set at 60 C and the speed
was varied in order to identify a draw ratio that resulted in the highest
tenacity when elongation to break was adjusted to be in the range of 55 ¨
65 %. The followed for Polymer Blend #1(0.8% PS) was: a draw ratio of
2.37 was found to result in the highest tenacity when elongation to break
was within the desired range (i.e., first godet roll speed=1900 m/min).
Examples 5 and 6 were performed with spinneret orifices
0.27 mm in diameter. Examples 7 and 8 were performed with spinneret
orifices 0.32 mm in diameter. Other spinning conditions are shown in
Table 2 and Table 4. Results are shown in Table 4.
Table 4: Results of Campaign #2
G1 G1 Draw Denier
Capillary DPF
Example Speed Temp Ratio CV
D (mm)(g/9000m) (0/0)
(m/min) ( C) (G2/G1)
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Comp.Ex.F 0.27 2150 60 2.09 2.1 2.80
Comp.Ex.G 0.27 1900 60 2.37 2.1 2.82
Comp.Ex.H 0.27 1750 60 2.57 2.1 2.79
Ex.5 0.27 1900 73 2.37 2.1 3.11
Ex.6 0.27 1900 85 2.37 2.1 2.74
Comp.Ex.I 0.32 2150 60 2.09 2.0 2.62
Comp.Ex.J 0.32 1900 60 2.37 2.1 2.79
Comp.Ex.K 0.32 1750 60 2.57 2.1 2.88
Ex.7 0.32 1900 73 2.37 2.1 3.39
Ex.8 0.32 1900 85 2.37 2.1 3.06
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CAMPAIGN #3 - SPINNING MACHINE #2
The same batch of PS/PTT containing 0.80 % by weight PS
as employed in Campaign #2 was employed.
Melt spinning was effected using the same spinning machine
procedures and settings as described for Campaign #1, supra, except that
in these examples a 75 denier/36 filament yarn was spun and the quench
was a radial quench. Spinning conditions are shown in Table 3 and Table
5. Again the extruder heating zones were set respectively to 230/255/263
C. Spinneret diameter was 0.27 mm. Flow rates were controlled to 37.5
g/min. Results are shown in Table 5.
Table 5 Results of Campaign #3
G1 G1 Draw
DPF Denier
Example Speed Temp Ratio
(g/9000m) CV (%)
(m/min) ( C) (G2/G1)
Comp.Ex.L 1550 60 2.90 2.0 4.27
Comp.Ex.M 1450 60 3.10 2.1 3.04
Comp.Ex.N 1350 60 3.33 2.1 2.32
Ex.14 1450 73 3.10 2.1 2.45
Ex.15 1350 73 3.33 2.1 1.64
Ex.16 1450 85 3.10 2.1 1.90
Ex.17 1350 85 3.33 2.1 1.72
Ex.18 1350 100 3.33 2.1 2.15
CAMPAIGN #4 -- SPINNING MACHINE #2
A third blend of 0.8 % PS in PTT was made in a manner
identical to that of Blend #2, described supra.
Melt spinning was effected using the same spinning machine
procedures and settings as described for Campaign #3, supra, except that
in these examples a 75 denier/72 filament yarn was spun. Spinning
conditions are shown in Table 3 and Table 6. Again the extruder heating
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PCT/US2011/052797
zones were set respectively to 230/255/263 C. Spinneret diameter was
0.27 mm. Flow rates were controlled to 37.5 g/min except where noted in
Ex 12 and Ex 13. Results are shown in Table 6.
Table 6 Results of Campaign #4
Flowrat G1 G1 G2 Draw DPF
Denier
Example e Speed Temp Speed Ratio (g/9000m
CV (0/0)
(g/min) (m/min) ( C) (m/min) (G2/G1) )
Ex.9 37.5 1550 73 4500 2.90 1.1 1.73
Ex.10 37.5 1550 79 4500 2.90 1.0 1.69
Ex.11 37.5 1550 85 4500 2.90 1.0 1.83
Ex.12 35.4 1400 79 4250 3.04 1.0 1.55
Ex.13 39.6 1750 79 4750 2.71 1.0 1.84
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