WO2024211874A1

WO2024211874A1 - Bicomponent yarn with improved bulk and hand-feel and elastic fabrics including the bicomponent yarn

Info

Publication number: WO2024211874A1
Application number: PCT/US2024/023538
Authority: WO
Inventors: Geoffrey David Hietpas; Paul Wu
Original assignee: The Lycra Company Llc
Priority date: 2023-04-07
Filing date: 2024-04-08
Publication date: 2024-10-10

Abstract

The invention includes fabrics and yarns including polyester bicomponent multifilament yarns. The bicomponent polyester yarn is made from polyethylene terephthalate and polytrimethylene terephthalate in a side by side or eccentric sheath core configuration. The yarns have an improved bulk and provide a more desirable hand- feel in fabrics compared to traditional polyester bicomponent yarns.

Description

BICOMPONENT YARN WITH IMPROVED BULK AND HAND-FEEL AND ELASTIC FABRICS INCLUDING THE BICOMPONENT YARN

Field of the Invention

[0001] The invention includes fabrics and yarns including polyester bicomponent multifilament yams. The yarns have an improved bulk and provide a more desirable handfeel in fabrics compared to traditional bicomponent yams.

Summary of Related Technology

[0002] Bicomponent polyester yam made from polyethylene terephthalate and polytrimethylene terephthalate in a side by side or eccentric sheath core configuration (or any fiber meeting the FTC definition of elasterell-p), will have as a distinguishing property, a coiled structure (also known as spiral crimp) that comes from the differential shrinkage of the two components in the side-by-side fiber. The polyethylene terephthalate or polytrimethylene terephthalate which are each present in distinct domains in the fiber in a side-by-side configuration along the length of the fiber, each shrink to a different extent, and when this happens, the fiber is forced into a coiled structure.

[0003] For textile applications, the bicomponent fiber is sold as a multifilament bundle referred to as a ‘yam’ (for example sold commercially as LYCRA®T400® fiber by The LYCRA Company). This yarn is comprised of multiple filaments that are each in the range of 0.9 to 3.0 denier per filament. A typical yam would have a total denier of 50 which is comprised on 34 filaments. Other examples include 70 denier-68 filaments, 150 denier-72 filaments, etc. Any total yam denier is possible by combining multiples of the individual 0.9 to 3.0 denier filaments.

[0004] A common consumer complaint about fabrics made with this fiber is that the hand feel is harsh. This is believed to be due to the high contraction and coiled nature of the fiber, which is a property that is inherent to the fiber as recognized in the Federal Trade Commission (FTC) definition of elasterell-p. The FTC defines "elasterell-p" as fiber formed by the interaction of two or more chemically distinct polymers (of which none exceeds 85% by weight) which contains ester groups as the dominant functional unit (at least 85% by weight of the total polymer content of the fiber) and which, if stretched at least 100%', durably and rapidly reverts substantially to its unstretched length when the tension is removed. [0005] The application of any process that causes the fiber to shrink (which could include placement in water above 40°C, application of steam, or dry heat above 60°C) causes all of the individual filaments to contract into a tight multifilament coil. This multifilament coil no longer exhibits the benefit of being comprised of individual 0.9 to 3.0 denier filaments, but rather the yarn has the tactile characteristics of the much higher denier that is a result of the combined deniers of the individual filaments. It is well recognized in the industry and by the consumer that finer (lower denier) yams have a more desirable hand feel, and so in elasterell- p fabrics this tight multifilament coil leads to undesirable hand-feel vs. a similar yam denier made from homofiber filaments.

SUMMARY OF THE INVENTION

[0006] In order to improve the hand-feel of fabrics including a bicomponent polyester, such as elasterell-p also known as elastomultiester, applicant has sought to disrupt the coil in a yam formed by the innate crimp in the structure of the filaments. This has been overcome by the development of a new multifilament bicomponent yarn that reduces the ability of the yam to contract into a tight multifilament bundle. The reduced ability to contract into a tight bundle in the yarn is enabled by making the yam out of filaments that have different filament deniers, filaments with an oval cross-section, filaments of mixed cross-sections, filaments of mixed polymer ratios, or filaments with a sufficiently low crimp potential (CP) combined with a low crimp shrinkage (CS) which reduces the tendency of the filaments to pack tightly together. Each of these alternatives may be combined to provide different characteristics in the yarn.

[0007] For the above example of different filament denier in the case of an existing 50 denier yam comprised of 34 filaments would contain 34 individual filaments that are each (50/34 - 1.47 denier). This means all 34 filaments have the same properties and the same degree of potential to form spiral crimp when expose to conditions that lead to shrinkage. Surprisingly, we have found that with a spinneret for fiber spinning can be made to deliver these 34 filaments with a range of deniers (for example 50 denier yarn comprised of 12 filaments of 1.3 denier, 12 filaments of 1.5 denier, and 10 filaments of 1.7 denier.) This variation of denier leads to variation of polymer orientation in the fiber, which leads to variation in the degree of spiral crimp formation in the yarn, which provides sufficient variation in the yarn bundle to perturb the structure of the multifilament coil such that the individual fibers are less tightly bound and therefore provide an effective lower denier for hand fell when touched by the consumer. The invention includes the fiber and the process of the making the fiber using the multi-sized holes in the spinneret, along with the fiber spinning process that results in a yam that continues to have sufficient development of spiral crimp to deliver the elastic properties to fabric recognized as being inherent in Elasterell-p.

BRIEF DESCRIPTION OF THE FIGURES

[0008] Figure 1 is an image of the FACE side of both fabrics of the circular knit fabric of the fiber of example 1A.

[0009] Figure 2 is an image of the BACK side of both fabrics of the circular knit fabric of the fiber of example 1A.

[0010] Figure 3 is an image of the FACE side of both fabrics of the circular knit fabric of the fiber of example 1AC.

[0011] Figure 4 is an image of the BACK side of both fabrics of the circular knit fabric of the fiber of example 1AC.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The fabrics described herein include polyester bicomponent fabric and may include other fibers. The polyester bicomponent filaments are made into a yarn out of filaments that have one or more of the following: different filament deniers, filament with an oval crosssection, filaments of mixed cross-sections, filaments of mixed polymer ratios, or filaments with a sufficiently low crimp potential (CP) combined with a low crimp shrinkage (CS) which reduces the tendency of the filaments to pack tightly together. Each of these alternatives may be combined to provide different characteristics in the yam.

[0013] In one aspect of the invention, there is provided a bicomponent multifilament yam having at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament are independently selected and differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof. [0014] In another aspect of the invention, there is provided an elastic fabric including a bicomponent multifilament yam having at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament are independently selected and differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof.

[0015] In another aspect of the invention, the elastic fabric further comprises a second yarn. The second yam may be selected from materials including cotton, polyester, polyurethane, polyolefin, polyamide, and combinations thereof.

[0016] In one aspect of the invention, the elastic fabric may include a knit or woven elastic fabric.

[0017] In one desirable aspect of the invention, the first component and the second component of said bicomponent yarn may include a polyester selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate.

[0018] In another aspect of the invention, the deniers per filament (dpf) in the bicomponent multifilament yam may be from about 20 to about 150 dpf. Desirably the dpf may range from about 30 to about 100, about 40 to about 90, about 50 to about 80 and about 60 to about 75.

[0019] In another aspect of the invention, the dpf range of the bicomponent multifilament yam may be from about 0.8 to about 4.0, 1.0 to about 3.0, 1.5 to about 2.5 and 2 to about 4. In one desirable aspect of the invention, the dpf range in the bicomponent multifilament yam may be from about 1.0 to about 3.5.

[0020] In another aspect of the invention, the ratio of the first component to the second component may be about 30:70 to about 70:30.

[0021] In another aspect of the invention, the cross-section of the filament has a 1.5:1 or greater aspect ratio. In another aspect of the invention, the cross-section shape of the filament may be round, oval, snowman, or ribbon. [0022] In another aspect of the invention, the crimp shrinkage (CS) may be from about 0.5% to about 10%, calculated as described herein. Desirably the crimp shrinkage may be from about 2% to about 8%, about 4 to about 10% about 4 to about 8%, and about 5 to about 10%.

[0023] In another aspect of the invention, the crimp potential may be about CP 40 % to about 70%, about 45% to about 65 %, and 55 to about 70 %.

[0024] In yet another aspect of the invention there is provided a method for preparing a bicomponent multifilament yam including at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof, including the steps of extruding a polymer including a first component and second component for each filament through separate holes in a spinneret; wherein one or more of the following is present: (a) said holes differ in size; (b) said holes differ in cross-section; (c) within each of said holes, said first component and second component have different ratios; and (d) combinations of (a)-(c).

[0025] In yet another aspect of the invention there is provided a method for preparing a bicomponent multifilament yam wherein a first bicomponent filament is prepared by selecting one of more of the characteristics of (a), (b), or (c) as recited above, and a second bicomponent filament is also prepared by selecting one of more of the characteristics of (a), (b), or (c) that are the same or differ from the first bicomponent; and wherein both first and second are combined in to a single multifilament yam by entangling, twisting, or air-jet texturing process. In one aspect of the invention there may be some but not complete overlap of the chosen characteristics between the first and second bicomponent multifilament yarns. In another aspect of the invention, there may be complete overlap of the chosen characteristics between the first and second bicomponent multifilament yarns.

[0026] In a particularly useful aspect of the invention the bicomponent multifilament yarns may include poly(ethylene terephthalate) (“PET”) and poly(trimethylene terephthalate) (“PTT”) wherein the bicomponent filaments may have a substantially oval cross-section shape having an aspect ratio A:B of about 2: 1 to about 5:1 wherein A is a fiber cross-section major axis length and B is a fiber cross-section minor axis length; wherein the yams may have a polymer interface substantially perpendicular to the major axis; and where the yams may include a cross-section configuration selected from of side-by-side and eccentric sheathcore configurations.

[0027] In one particularly useful aspect of the invention there is provided an elastic fabric including a bicomponent multifilament yam including 2GT/3GT wherein the crimp potential may be about 40% to about 70% and the crimp shrinkage may be about 0.5% to about 8%. In another particularly useful aspect of the invention there is provided an elastic fabric including a bicomponent multifilament yarn including 2GT/3GT wherein the crimp potential may be about less than 60% and the crimp shrinkage may be about 0.5% to about 6%.

[0028] The bicomponent filaments having different crimp characteristics may be extruded simultaneously from a spinneret including holes of different sizes or shapes and then combined to form a multifilament bicomponent yarn as described herein.

[0029] Alternatively, the bicomponent filaments may be prepared and extruded through separate spinnerets and subsequently combined to a single multifilament bicomponent yam including the different filaments. The filaments may be combined through any known process such as twisting or air jet interlacing.

[0030] The bicomponent filaments herein may be any of a variety of different cross-sections. This may include round, oval, ribbon, scalloped oval, keyhole, and snowman, among others.

[0031] Bicomponent filaments of different cross-sections may be ribbon- like, such as those disclosed in US7195819B2, which is incorporated herein by references in its entirety.

[0032] As used herein, “bicomponent fibers” means staple fibers in which two polymers of the same general class are in a side-by-side or eccentric sheath-core relationship or configuration.

[0033] As used herein, the term “side-by-side” means that the two components of the bicomponent fiber are immediately adjacent to one another and that no more than a minor portion of either component is within a concave portion of the other component. “Eccentric sheath-core” means that one of the two components completely surrounds the other component but that the two components are not coaxial. [0034] As used herein, “substantially oval’" means that an area of a cross-section of the fiber, measured perpendicular to the longitudinal axis of the fiber, deviates by less than about 20% from that of an oval shape. The general term “oval” includes “ovoid” (egg-shaped) and “elliptical” within its meaning. Such a shape typically has two axes at right angles through the center of the shape, a major axis (A), and a minor axis (B), where the length of the major axis A is greater than the length of the minor axis B. In the special case of a perfect ellipse, the oval is described by a locus of points whose sum of whose distances from two foci is constant and equal to A. In the more general case of an ovoid, one end of the oval can be larger than the other, so that the sum of the distances from two foci is not necessarily constant and can vary by 20% or more from elliptical.

[0035] As used herein, a “substantially oval” cross-section periphery may have or may lack constant curvature.

|0036| “Aspect ratio” means the ratio of the length of the major axis (A) of the oval to the length of the minor axis (B) of the oval, in other words A:B.

[0037] “Polymer interface” means the boundary between the polymeric yarns being used meet, for example, the boundary between poly(ethylene terephthalate) and poly(trimethylene terephthalate). The polymer interface may be substantially linear or curved.

[0038] “Intimate blending” means the process of gravimetrically and thoroughly mixing dissimilar fibers in an opening room (for example with a weigh-pan hopper feeder) before feeding the mixture to the card or of mixing the fibers in a dual feed chute on the card. “Drawframe blending” means the process of blending carded bicomponent fiber slivers with one or more other carded fiber slivers as the slivers are being drawn on the drawframe.

[0039] The fibers of the invention desirably have a substantially oval cross-section shape with an aspect ratio A:B of about 2:1 to about 5:1 , (examples include about 2.6: 1 to about 3.9:1, and about 3.1 :1 to about 3.9:1). When the aspect ratio is too high or too low, the fiber can exhibit undesirable glitter and low dye yield, and spun yarn comprising the fiber can be insufficiently uniform. The fiber also has a polymer interface substantially perpendicular to the major axis of the cross-section, and a free-fiber length retention from about 40% to about 85%. Such oval filaments can be spun from spinneret orifices that are slot-shaped (flat or with side bulges), oval, and the like.

[0040] The oval cross-section shape is substantially free of grooves in the cross-section periphery. That is, there is only one maximum when the length of the minor axis is plotted against the length of the major axis. Examples of cross-section shapes which do have grooves are “snowman”, “scalloped oval”, and “keyhole” cross-sections.

[0041] Bicomponent filaments may also include different polymer ratios as shown in US20060008644, which is incorporated herein by reference, in its entirety.

[0042] By varying the polymer ratio fed to individual apertures of a spinneret, such as using the method described in U.S. Pat. No. 3,671,379 to Evans et al., a single spinneret may be used to produce multiple fibers, each having varying ratios of distinct polymers. These fibers can then be wound into a yarn of mixed ratio bi-component fibers without the need to separately wind other yarns together to form a larger yarn. The various bi-component fibers, or yams of these fibers, having mixed component ratios, are combined to form a single yam that may be used to knit fabrics.

[0043] The weight ratio of individual bi-component fibers of the yam of the invention may be any weight ratio of one component versus the other, but typically the ratio may be between about 75/25 to 25/75, more typically between about 70/30 to 30/70.

[0044] Regardless of the weight ratios of the individual fibers, the overall or net weight ratio of the components in the yam may be about 45/55 to about 75/25, wherein the first number represents the component having the repeating unit of smaller mass. Preferably, the overall net weight ratio may be asymmetric, favoring higher amounts of the component having the smaller repeating unit, i.e. PET in preferred embodiments of the invention using for example PET and PTT as components.

[0045] The weight ratios of one component versus the other may vary between the fibers within the yarn, thus creating the mixed-ratio bi-component fibers. The components of various filaments may typically differ by about 10 weight percent or more in any particular yam. For example, a yarn might typically include multiple bi-component fibers of 30/70, 40/60, 50/50, 60/40 and 70/30, but not typically 30/70, 33/67, 50/50, 67/33, and 70/30. Differences of less than about 10 weight percent may not produce bi-component fibers with sufficient differences in crimp frequency to achieve the most desired levels of avoiding follow-the-leader crimping.

[0046] Once the yarns are spun, they may be used to knit fabrics which have desirable characteristics, such as a smooth and silky touch.

[0047] Another suitable bicomponent filament may be one including a CP of about 40 to about 70 and where the CS may be below about 8. For example, a useful bicomponent filament may have a CP of about 40 to about 60, 50 to about 65; and a CS about 1 to about 6. Methods for preparing such fibers are well-known and described in US6868662B2, which is incorporated herein by reference in its entirety.

[0048] Crimp Potential (“CP”) and Crimp Shrinkage (“CS”) were determined by measuring the length of a yarn skein under standard loads before and after dry heat treatment. A 7000 denier (7778 dtex) (measured as doubled), '/2-inch wide skein sample was prepared from the yarn to be tested. The skein sample was mounted on the magazine of a textured yam tester (Texturmat-ME, Lawson Hemphill Sales Co.), and a 700 g (100 mg/d) load was applied for at least 10 seconds. The length of the skein was determined and reported as LI. The sample was removed from the tester, placed in a hot air oven (Lawson Hemphill Sales Co.) held at 121.0+0.2° C. for 5 minutes, removed from the oven, and allowed to cool for 20 minutes. The sample was returned to the textured yam tester, a l0.5 g (1.5 mg/d) load was applied, and the skein length was recorded as L2. Finally, a 700 g load was applied again, and the length of the skein was determined and recorded as L3. % CP and % CS were calculated from the following formulae:

[0049] All the samples in the Examples had Crimp Shrinkage of 7-9%. Since Crimp Contraction % (CC%) is calculated as 100x(L3-L2)/L3, Crimp Potential is related to Crimp Contraction according to the following formula: CP=CCxL 3 /L 2 (3) and empirically by: CP=2.8xCC-43.9 (4)

[0050] A Crimp Potential value of 39% is equivalent to a Crimp Contraction value of 30%.

[0051] Turning now to the Figures, Figure 1 is an image of the face side of both fabrics of the circular knit fabric of the fiber of Example 1 A herein. A multifilament bicomponent yarn was produced by melt spinning to have a total denier of 50.7. This yarn was comprised of 34 filaments. The CP was 67 and the CS was 8.5. The polymer ratio of each filament was 60% poly(ethylene terephthalate) (PET) and 40% poly(trimethylene terephthalate) (PTT). The total elongation to break was 22% and the breaking tenacity was 4.3 grams per denier. The 34 individual filaments that comprise the 50.7 denier total were of different deniers in the range from 1.2 denier to 2.0 denier. A standard spin finish was applied at 2.0% w/w to ensure good package formation and control of friction and static during subsequent knitting and weaving processes.

[0052] Figure 2 is an image of the back side of both fabrics of the circular knit fabric of the fiber of Example 1 A herein.

[0053] Figure 3 is an image of the face side of both fabrics of the circular knit fabric of the fiber of Example 1 AC herein. A multifilament bicomponent yarn was produced according to the process of Example 1 A, in which the 34 filaments were all 1.5 dpf (denier per filament).

[0054] Figure 4 is an image of the back side of both fabrics of the circular knit fabric of the fiber of Example 1AC herein.

ASPECTS OF THE INVENTION

(ASPECT 1.) An elastic fabric including a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament are independently selected and differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combi nations thereof.

(A SPECT 2.). The elastic fabric of (A SPECT 1), further comprising a second yarn.

(A SPECT 3.) The elastic fabric of any one of (A SPECTS 1-2), further comprising a second yarn selected from the group consisting of cotton, polyester, polyurethane, polyolefin, polyamide, and combi nations thereof.

(A SPECT 4.) The elastic fabric of any one of (A SPECTS 1-3), wherein the elastic fabric is a knit or woven elastic fabric.

(A SPECT 5.) The elastic fabric of any one of (A SPECTS 1-4), wherein the denier of said bicomponent multifilament yarn is about 20 to about 150.

(A SPECT 6.). The elastic fabric of any one of (A SPECTS 1- 5), wherein the first component and the second component of said bicomponent yarn include a polyester selected from the group consisting of polyethylene terephthalate, poly tri methylene terephthalate, and polybutylene terephthalate.

(A SPECT 7.). The elastic fabric of any one of (A SPECTS 1-6), wherein the range deniers per filament in the bicomponent multifilament yarn is about 0.8 to about 4.0.

(A SPECT 8.). The elastic fabric of any one of (A SPECTS 1-7), wherein the range deniers per filament in the bicomponent multifilament yarn is about 1.0 to about 3.5.

(A SPECT 9.). The elastic fabric of any one of (A SPECTS 1-8), wherein the ratio of the fi rst component to the second component is about 30:70 to about 70:30.

(A SPECT 10.). The elastic fabric of any one of (A SPE CTS 1- 9), wherein the cross- section of the filament has a 1.5:1 or greater aspect ratio.

(A SPECT 11.). The elastic fabric of any one of (A SPE CTS 1-10), wherein the cross- section of the filament is selected from round, oval, snowman, or ribbon.

(A SPECT 12.). The elastic fabric of any one of (A SPE CTS 1-11), wherein the crimp shrinkage is about 0.5% to about 10%. (A SPECT 13.). The elastic fabric of any one of (A SPE CTS 1-12), wherein the crimp potential is about 40 C P 40 % to about 70%.

(A SPECT 14.). A bicomponent multifilament yarn of any one of (A SPECTS 1-13) having at least a fi rst bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament are independently selected and differ i n at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof.

(A SPECT 15.). A method for preparing a bicomponent multifilament yarn of any one of (A SPECTS 1-14) having at least a first bicomponent filament and a second bicomponent filament, wherei n said first filament and said second filament differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof, comprising extruding a polymer includi ng a first component and second component for each filament through separate holes in a spi nneret; wherein (a) said holes differ i n size; (b) said holes differ in cross- section; (c) within each of said holes, said first component and second component have different ratios; and (d) combinations thereof.

(A SPECT 16.). A method for preparing a bicomponent multifi lament yarn of any one of (A SPECTS 1-15) having at least a first bicomponent filament and a second bicomponent filament, wherei n said first filament and said second filament have a partial overlap of the same characteristics which may be selected from (a) denier per fi lament; (b) ratio of a first component of said filament to a second component of said fi lament; (c) cross-section; and (d) combinations thereof, wherein both first and second are combined in to a single multifilament yarn by entangl ing, twisting, or air-jet texturi ng process.

(A SPECT 17.). A bicomponent multifilament yarn accordi ng to any one of (A SPECTS 1-16) comprising poly (ethyl ene terephthalate) and poly (tri methylene terephthalate) wherein the bicomponent filaments have a substantially oval cross-section shape having an aspect ratio A :B of about 2: 1 to about 5:1 wherei n A is a fiber cross-section major axis length and B is a fiber cross-section minor axis length, a polymer interface substantial ly perpendicular to the major axis, and a cross-section configuration selected from the group consisting of side-by- side and eccentric sheath-core. (A SPECT 18.). A n elastic fabric according to any one of (A SPECTS 1-17) i ncluding a bicomponent multifilament yarn including 2GT/3GT wherein the crimp potential is about 40% to about 70% and the crimp shri nkage is about 0.5% to about 8%.

(A SPECT 19.). A n elastic fabric according to any one of (A SPE CTS 1-18) including a bicomponent multifilament yarn including 2GT/3GT wherein the crimp potential is about less than 60% and the crimp shrinkage is about 0.5% to about 6%.

Examples

[0055] Example 1A - A multifilament bicomponent yarn was produced by melt spinning and to have a total denier of 50.7. This yarn was comprised of 34 filaments. The C P was 67 and the CS was 8.5. The polymer ratio of each filament was 60% poly (ethyl ene terephthalate) (PET) and 40% poly(tri methylene terephthalate) (PTT). The total elongation to break was 22% and the breaking tenacity was 4.3 grams per denier. The 34 individual filaments that comprise the 50.7 denier total were of different deniers in the range from 1.2 denier to 2.0 denier. A standard spin finish was applied at 2.0% w/w to ensure good package formation and control of friction and static during subsequent knitting and weaving processes.

[0056] Example 1A C - A multifilament bi component yarn was produced according to the process of Example 1A , in which the 34 filaments were all 1.5 dpf (denier per filament).

[0057] Example 2 - The multifilament yarns of Examples 1A and 1A C were knitted on a circular knitting machine and then dyed and finished conventionally with disperse dyes.

[0058] Example 3 - The multifilament yarns of Examples 1A and 1A C were each separately plated with a 50 denier 72 filament drawn texturized yarn (DTY ), in this case a DTY polyester yarn and knitted on a circular knitting machine and then dyed and finished conventionally with disperse dyes. The fabric that contained the 1A yarn was substantial ly softer and had higher drape, i .e. how the fabric hangs under its own weight. DTY s are also known as a crimped yarns.

[0059] Example 4F - A multifilament bi component yarn was produced by melt spinning and to have a total denier of 50. This yarn was comprised of 46 filaments. The C P was 50 and the CS was 5.0. The polymer ratio of each filament was 60% poly( ethylene terephthalate) and 40% polyftri methylene terephthalate). A standard spin finish was appl ied at 2.0% w/w to ensure good package formation and control of friction and static during subsequent knitting and weaving processes. The multifilament bicomponent yarn was knitted on a circular knitting machine. It was dyed conventionally using disperse dyes and dried at 140C on a stentor frame. The fabric had a soft hand-feel and desirable drape.

Claims

CLAIMS:

1. An elastic fabric including a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament are independently selected and differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof.

2. The elastic fabric of claim 1 , further comprising a second yarn.

3. The elastic fabric of claim 1 , further comprising a second yarn selected from the group consisting of cotton, polyester, polyurethane, polyolefin, polyamide, and combinations thereof.

4. The elastic fabric of claim 1, wherein the elastic fabric is a knit or woven elastic fabric.

5. The elastic fabric of claim 1 , wherein the denier of said bicomponent multifilament yarn is about 20 to about 150.

6. The elastic fabric of claim 1 , wherein the first component and the second component of said bicomponent yarn include a polyester selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate.

7. The elastic fabric of claim 1 , wherein the range deniers per filament in the bicomponent multifilament yam is about 0.8 to about 4.0.

8. The elastic fabric of claim 1 , wherein the range deniers per filament in the bicomponent multifilament yam is about 1.0 to about 3.5.

9. The elastic fabric of claim 1 , wherein the ratio of the first component to the second component is about 30:70 to about 70:30.

10. The elastic fabric of claim 1, wherein the cross-section of the filament has a 1.5:1 or greater aspect ratio.

1 1. The elastic fabric of claim 1, wherein the cross-section of the filament is selected from round, oval, snowman, or ribbon.

12. The elastic fabric of claim 1, wherein the crimp shrinkage is about 0.5% to about

10%.

13. The elastic fabric of claim 1, wherein the crimp potential is about 40 CP 40 % to about 70%.

14. A bicomponent multifilament yam having at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament are independently selected and differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof.

15. A method for preparing a bicomponent multifilament yam having at least a first bicomponent filament and a second bicomponent filament, wherein said first filament and said second filament differ in at least one of the following ways: (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) crosssection; and (d) combinations thereof, comprising extruding a polymer including a first component and second component for each filament through separate holes in a spinneret; wherein (a) said holes differ in size; (b) said holes differ in cross-section; (c) within each of said holes, said first component and second component have different ratios; and (d) combinations thereof.

16. A method for preparing a bicomponent multifilament yam wherein a first bicomponent filament is prepared by selecting one of more characteristics of (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) crosssection; and (d) combinations thereof; and a second bicomponent filament is prepared using one or more characteristics of (a) denier per filament; (b) ratio of a first component of said filament to a second component of said filament; (c) cross-section; and (d) combinations thereof; wherein both first and second bicomponent multifilament yams are combined in to a single multifilament yam by entangling, twisting, or air-jet texturing process.

17. A bicomponent multifilament yam comprising poly (ethylene terephthalate) and poly(trimethylene terephthalate) wherein the bicomponent filaments have a substantially oval cross-section shape having an aspect ratio A:B of about 2: 1 to about 5:1 wherein A is a fiber cross-section major axis length and B is a fiber cross-section minor axis length, a polymer interface substantially perpendicular to the major axis, a cross-section configuration selected from the group consisting of side-by-side and eccentric sheath-core.

18. An elastic fabric including a bicomponent multifilament yarn including 2GT/3GT wherein the crimp potential is about 40% to about 70% and the crimp shrinkage is about 0.5% to about 8%.

19. An elastic fabric including a bicomponent multifilament yarn including 2GT/3GT wherein the crimp potential is about less than 60% and the crimp shrinkage is about 0.5% to about 6%.