CN120936761A - Bicomponent yarns with improved loft and hand feel, as well as elastic fabrics including bicomponent yarns. - Google Patents

Abstract

This invention includes fabrics and yarns, said yarns comprising polyester bicomponent multifilament yarns. The bicomponent polyester yarns are made of polyethylene terephthalate and polypropylene terephthalate in a side-by-side or eccentric core-sheath configuration. Compared to conventional polyester bicomponent yarns, said yarns have improved bulk and provide a more desirable hand feel in fabrics.

Description

Bicomponent yarns having improved bulk and hand and elastic fabrics comprising the same

Technical Field

The present invention includes fabrics and yarns comprising polyester bicomponent multifilament yarns. The yarn has improved bulk and provides a more desirable hand in fabrics than conventional bicomponent yarns.

Summary of the related art

Bicomponent polyester yarns made from polyethylene terephthalate and polypropylene terephthalate in a side-by-side or eccentric sheath-core configuration (or any fiber conforming to the definition of FTC vs elasterell-p) will have a winding structure (also known as a spiral crimp) as a distinguishing characteristic that results from differential shrinkage of the two components in the side-by-side fiber. The polyethylene terephthalate or polypropylene terephthalate, each present in a side-by-side configuration in different domains in the fiber, shrink to a different extent along the length of the fiber and when this occurs, the fiber is forced into a coiled configuration.

For textile applications, the bicomponent fibers are sold as multifilament bundles called 'yarns' (e.g., commercially sold as LYCRA bulk T400 fibers by LYCRA company). Such yarns are comprised of a plurality of filaments, each filament being in the range of 0.9 to 3.0 denier per filament. A typical yarn will have a total denier of 50, consisting of 34 filaments. Other examples include 70 denier-68 filaments, 150 denier-72 filaments, etc. By combining multiple filaments of individual 0.9 to 3.0 denier filaments, it is possible to achieve any total yarn denier.

A common consumer complaint about fabrics made with such fibers is a rough hand. This is believed to be due to the high shrinkage and winding properties of the fibers, which are inherent to the fibers as recognized in the definition of elasterell-p by the Federal Trade Commission (FTC). FTC defines "elasterell-p" as a fiber formed from the interaction of two or more chemically distinct polymers (none of which exceeds 85% by weight) that contains ester groups as the primary functional units (which are at least 85% by weight of the total polymer content of the fiber) and which can permanently and rapidly recover substantially to its unstretched length after removal of the tension if stretched by at least 100%.

The application of any process that causes shrinkage of the fibers, which may include placing in water above 40 ℃, applying steam, or dry heat above 60 ℃, causes all individual filaments to compact into a tight multifilament winding. Such multifilament windings no longer exhibit the benefit of being composed of individual 0.9 to 3.0 denier filaments, but rather the yarn has the tactile feature of a higher denier as a result of the combined denier of the individual filaments. It is widely accepted by both the industry and consumers that finer (lower denier) yarns have a more desirable hand and, therefore, in elasterell-p fabrics, such tight multifilament windings can result in an undesirable hand as opposed to a similar yarn denier made from monocomponent fiber filaments.

Disclosure of Invention

To improve the hand of fabrics comprising bicomponent polyesters, such as elasterell-p, also known as elastic polyester fibers (elastomultiester), applicants have attempted to break the loops in the yarn formed by the inherent crimp in the filament structure. This has been overcome by developing a new multifilament bicomponent yarn that reduces the ability of the yarn to compact into a tight multifilament bundle. The ability to compact into tight bundles in yarns is achieved by making the yarn from filaments having different filament deniers, filaments having oval cross sections, filaments having mixed polymer ratios, or filaments having a sufficiently low Crimp Potential (CP) in combination with low crimp Contraction (CS) (reduced tendency of filaments to tightly bunch together). Each of these alternatives may be combined to provide different features in the yarn.

For the example of different filament deniers above, in the case of the existing 50 denier yarn, the yarn consisting of 34 filaments will contain 34 individual filaments, each individual filament being (50/34=1.47 denier). This means that all 34 filaments have the same properties and the same degree of potential for spiral crimp formation when exposed to conditions that result in shrinkage. Surprisingly, we have found that fiber spinning using a spinneret can be performed to provide these 34 filaments having a range of deniers (e.g., a 50 denier yarn consisting of 12 filaments of 1.3 deniers, 12 filaments of 1.5 deniers, and 10 filaments of 1.7 deniers). This change in denier results in a change in the orientation of the polymer in the fiber, which results in a change in the degree of spiral crimp formation in the yarn, which provides sufficient change in the yarn bundle to disrupt the structure of the multifilament windings so that the individual fibers are less tightly bound and thus provide an effective lower denier for the hand when touched by the consumer. The present invention includes fibers and processes for making fibers using multi-sized holes in a spinneret, as well as fiber spinning processes that produce yarns that continue to have sufficiently formed spiral crimp to provide the fabric with elastic properties believed to be inherent in ELASTERELL-p.

Drawings

Fig. 1 is an image of the front side of two fabrics of a circular knit fabric of fibers of example 1A.

Fig. 2 is an image of the back of two fabrics of a circular knit fabric of fibers of example 1A.

Fig. 3 is an image of the front side of two fabrics of the circular knit fabric of fibers of example 1 AC.

Fig. 4 is an image of the back of two fabrics of a circular knit fabric of fibers of example 1 AC.

Detailed Description

The fabrics described herein include polyester bicomponent fabrics and may include other fibers. The polyester bicomponent filaments are made from filaments having one or more of different filament denier, filaments having oval cross-sections, filaments having mixed polymer ratios, or filaments having a sufficiently low Crimp Potential (CP) in combination with low crimp Contraction (CS) (reduced tendency of filaments to tightly group together). Each of these alternatives may be combined to provide different features in the yarn.

In one aspect of the present invention, there is provided a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament are independently selected and differ in at least one of (a) denier per filament, (b) ratio of the first component of the filament to the second component of the filament, (c) cross section, and (d) combinations thereof.

In another aspect of the invention, an elastic fabric is provided comprising a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament are independently selected and differ in at least one of (a) denier per filament, (b) ratio of the first component of the filaments to the second component of the filaments, (c) cross section, and (d) combinations thereof.

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

In one aspect of the invention, the elastic fabric may comprise a knitted or woven elastic fabric.

In a desired aspect of the invention, the first and second components of the bicomponent yarn may comprise a polyester selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate.

In another aspect of the invention, the bicomponent multifilament yarn may have a denier per filament (dpf) of 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.

In another aspect of the invention, the dpf of the bicomponent multifilament yarn may range 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 of the bicomponent multifilament yarn may range from about 1.0 to about 3.5.

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

In another aspect of the invention, the cross-section of the filaments has an aspect ratio of 1.5:1 or greater. In another aspect of the invention, the cross-sectional shape of the filaments may be circular, oval, snowman, or ribbon.

In another aspect of the invention, the crimp Contraction (CS) may be from about 0.5% to about 10%, calculated as described herein. Desirably, the crimp contraction may be from about 2% to about 8%, from about 4% to about 10%, from about 4% to about 8%, and from about 5% to about 10%.

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%.

In yet another aspect of the present invention, a process for preparing a bicomponent multifilament yarn comprising at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament differ in at least one of (a) denier per filament, (b) ratio of the first component of the filament to the second component of the filament, (c) cross-sectional area, and (d) combinations thereof, is provided, the process comprising the steps of extruding a polymer comprising the first component and the second component of each filament through separate orifices in a spinneret, wherein one or more of (a) the orifices differ in size, (b) the orifices differ in cross-section, (c) the first component and the second component have different ratios within each of the orifices, and (d) combinations of (a) through (c) are present.

In yet another aspect of the present invention, there is provided a process for preparing a bicomponent multifilament yarn wherein a first bicomponent filament is prepared by selecting one or more of the features of (a), (b) or (c) as described above and a second bicomponent filament is also prepared by selecting one or more of the features of (a), (b) or (c) the same as or different from the first bicomponent filament, and wherein the first and second are combined into a single multifilament yarn by a entangling, twisting or jet texturing process. In one aspect of the invention, there may be some, but not complete, overlap of selected features between the first and second bicomponent multifilament yarns. In another aspect of the invention, there may be a complete overlap of selected features between the first bicomponent multifilament yarn and the second bicomponent multifilament yarn.

In a particularly useful aspect of the invention, the bicomponent multifilament yarn may comprise poly (ethylene terephthalate) ("PET") and poly (propylene terephthalate) ("PTT"), wherein the bicomponent filaments may have a substantially oval cross-sectional shape with an aspect ratio a: B of about 2:1 to about 5:1, wherein a is the fiber cross-sectional major axis length and B is the fiber cross-sectional minor axis length, wherein the yarn may have a polymer interface substantially perpendicular to the major axis, and wherein the yarn may comprise a cross-sectional configuration selected from the group consisting of a side-by-side configuration and an eccentric sheath-core configuration.

In a particularly useful aspect of the invention, an elastic fabric is provided comprising a bicomponent multifilament yarn comprising 2GT/3GT, wherein the crimp potential may be from about 40% to about 70% and the crimp contraction may be from about 0.5% to about 8%. In another particularly useful aspect of the invention, an elastic fabric is provided comprising a bicomponent multifilament yarn comprising 2GT/3GT, wherein the crimp potential may be less than about 60% and the crimp contraction may be from about 0.5% to about 6%.

Bicomponent filaments having different crimp characteristics can be simultaneously extruded from spinnerets comprising holes of different sizes or shapes and then combined to form a multifilament bicomponent yarn as described herein.

Alternatively, bicomponent filaments can be prepared and extruded through separate spinnerets and subsequently combined into a single multifilament bicomponent yarn comprising different filaments. The filaments may be combined by any known process, such as twisting or air interlacing.

The bicomponent filaments herein may be any of a variety of different cross-sections. This may include circular, oval, ribbon, fan oval, keyhole, snowman, and the like.

Bicomponent filaments having different cross-sections can be ribbon-like, such as those disclosed in US7195819B2, which is incorporated herein by reference in its entirety.

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.

As used herein, the term "side-by-side" means that the two components of a bicomponent fiber are immediately adjacent to each other and that only a small portion of either component is located within the recessed portion of the other component. By "eccentric sheath-core" is meant that one of the two components completely surrounds the other component, but the two components are not coaxial.

As used herein, "substantially oval" means that the cross-sectional area of the fiber, measured perpendicular to the longitudinal axis of the fiber, differs from the area of the oval shape by less than about 20%. The general term "oval" includes in its meaning "oval" (egg-shaped) and "elliptical". Such shapes typically have two axes at right angles through the center of the shape, a major axis (a) and a minor axis (B), where the length of major axis a is greater than the length of minor axis B. In the special case of a positive ellipse, the oval shape is described by the locus of points whose sum of the distances from the two focal points is constant and equal to a. In the case of a more general oval, one end of the oval may be larger than the other, such that the sum of the distances from the two foci is not necessarily constant and may differ from the oval by 20% or more.

As used herein, the cross-sectional perimeter of a "substantially oval shape" may or may not have a constant curvature.

"Aspect ratio" means the ratio of the length of the long axis (A) of the oval to the length of the short axis (B) of the oval, in other words A: B.

"Polymer interface" means the boundary between the polymer yarns used, such as the boundary between poly (ethylene terephthalate) and poly (trimethylene terephthalate). The polymer interface may be substantially linear or curved.

By "intimate blending" is meant the process of weighing and thoroughly mixing the different fibers in an open room (e.g., using a weigh hopper feeder) prior to feeding the mixture into the carding machine, or mixing the fibers in a double feed trough on the carding machine. "drawing blending (DRAWFRAME BLENDING)" means the process of blending a carded bicomponent sliver with one or more other carded slivers as the sliver is drawn on a drawing frame.

The fibers of the present invention desirably have a substantially oval cross-sectional shape with an aspect ratio A: B of from about 2:1 to about 5:1 (examples include from about 2.6:1 to about 3.9:1 and from about 3.1:1 to about 3.9:1). When the aspect ratio is too high or too low, the fibers may exhibit undesirable sparkle and low dye uptake (yield), and spinning including the fibers may not be sufficiently uniform. The fibers also have a polymer interface substantially perpendicular to the long axis of the cross section and a free fiber length retention of about 40% to about 85%. Such oval filaments may be spun from slit-like (flattened or with side projections), oval, or like shaped orifices.

The oval cross-sectional shape is substantially free of grooves at the cross-sectional perimeter. That is, when the length of the short axis is plotted against the length of the long axis, there is only one maximum. Examples of cross-sectional shapes that do have grooves are "snowman", "fan oval", and "keyhole" cross-sections.

The bicomponent filaments may also include different polymer ratios, as shown in US20060008644, which is incorporated herein by reference in its entirety.

By varying the ratio of polymers fed to the individual orifices of the spinneret, such as using the method described in U.S. Pat. No. 3,671,379 to Evans et al, a single spinneret can be used to produce a plurality of fibers, each having a different polymer in a different ratio. These fibers can then be wound into yarns of mixed ratio bicomponent fibers without the need to individually wind other yarns together to form larger yarns. Various bicomponent fibers or yarns of these fibers having mixed component ratios are combined to form a single yarn useful in the knitted fabric.

The weight ratio of the individual bicomponent fibers of the yarns of the invention can be any weight ratio of one component to the other component, but typically the ratio can be between about 75/25 to 25/75, more typically between about 70/30 to 30/70.

Regardless of the weight ratio of the individual fibers, the total or net weight ratio of the components in the yarn may be from about 45/55 to about 75/25, with the first number representing the component having the repeat unit of lesser mass. Preferably, the total or net weight ratio may be asymmetric, which favors higher amounts of components with smaller repeat units, i.e. PET in preferred embodiments of the invention, for example using PET and PTT as components.

The weight ratio of one component to the other can be varied between fibers within the yarn to create a mixed ratio bicomponent fiber. The components of the various filaments may generally differ by about 10% by weight or more in any particular yarn. For example, yarns may typically include multiple bicomponent fibers of 30/70, 40/60, 50/50, 60/40, and 70/30, but typically do not include bicomponent fibers of 30/70, 33/67, 50/50, 67/33, and 70/30. Differences of less than about 10 weight percent may not produce bicomponent fibers having sufficient differences in crimp frequency to achieve the most desirable level of avoiding follow-up crimp (follow-up-the-LEADER CRIMPING).

Once the yarns are spun, they can be used to knit fabrics having desired characteristics, such as smooth and silky feel.

Another suitable bicomponent filament may be a bicomponent filament comprising a CP of about 40 to about 70, and CS may be less than about 8. For example, useful bicomponent filaments can have a CP of about 40 to about 60, 50 to about 65, and a CS of about 1 to about 6. Methods for preparing such fibers are well known and have been described in US6868662B2, which is incorporated herein by reference in its entirety.

Crimp potential ("CP") and crimp contraction ("CS") were determined by measuring the length of the skein under standard load before and after dry heat treatment. A sample of hank yarn 7000 denier (7778 dtex) (measured in doubled strands) 1 ⁄ inches wide was prepared from the yarn to be tested. The skein sample was mounted on the rack of a textured yarn tester (Texturmat-ME, lawson HEMPHILL SALES co.) and a load of 700 g (100 mg/d) was applied for at least 10 seconds. The length of the skein is determined and reported as L1. Samples were removed from the tester, placed in a hot-air stove (Lawson HEMPHILL SALES co.) maintained at 121.0±0.2 ℃ for 5 minutes, removed from the stove, and allowed to cool for 20 minutes. The sample was returned to the textured yarn tester, a load of 10.5 g (1.5 mg/d) was applied, and the skein length was recorded as L2. Finally, a load of 700 g was again applied and the length of the hank was measured and recorded as L3.% CP and% CS are calculated according to the following formula:

All samples in the examples had a crimp contraction of 7% to 9%. Since the curl shrinkage (CC%) was calculated as 100× (L3-L2)/L3, the curl potential was related to the curl shrinkage according to the following formula:

and empirically related by:

a curl potential value of 39% corresponds to a curl shrinkage value of 30%.

Turning now to the drawings, FIG. 1 is an image of the front faces of two pieces of a circular knit fabric of fibers of example 1A herein. Multifilament bicomponent yarns were produced by melt spinning to have a total denier of 50.7. This yarn consisted of 34 filaments. CP 67 and CS 8.5. The polymer ratio of each filament was 60% poly (ethylene terephthalate) (PET) and 40% poly (propylene terephthalate) (PTT). The total elongation at break was 22% and the fracture toughness was 4.3 g/denier. The 34 individual filaments, which make up a total of 50.7 denier, have different deniers ranging from 1.2 denier to 2.0 denier. Standard spin finish was applied at 2.0% w/w to ensure good package formation (package formation) and control of friction and static electricity during the subsequent knitting and weaving process.

Fig. 2 is an image of the back of two fabrics of a circular knit fabric of fibers of example 1A herein.

Fig. 3 is an image of the front side of two pieces of circular knit fabric of fibers of example 1AC herein. Multifilament bicomponent yarns were produced according to the process of example 1A, wherein 34 filaments were all 1.5 dpf (denier per filament).

Fig. 4 is an image of the back of two pieces of circular knit fabric of fibers of example 1AC herein.

Aspects of the invention

(Aspect 1.) an elastic fabric comprising a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament are independently selected and differ in at least one of (a) denier per filament, (b) ratio of the first component of the filaments to the second component of the filaments, (c) cross section, and (d) combinations thereof.

The elastic fabric of (aspect 2.) further comprising a second yarn.

(Aspect 3.) the elastic fabric of any one of (aspects 1-2), further comprising a second yarn selected from the group consisting of cotton, polyester, polyurethane, polyolefin, polyamide, and combinations thereof.

(Aspect 4.) the elastic fabric of any one of (aspects 1 to 3), wherein the elastic fabric is a knitted or woven elastic fabric.

(Aspect 5.) the elastic fabric of any one of (aspects 1 to 4), wherein the bicomponent multifilament yarn has a denier of about 20 to about 150.

The elastic fabric of any one of (aspects 1 to 5), wherein the first component and the second component of the bicomponent yarn comprise a polyester selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate.

The elastic fabric of any one of (aspects 1 to 6), wherein the bicomponent multifilament yarn has a denier per filament in the range of about 0.8 to about 4.0.

The elastic fabric of any one of (aspects 1 to 7), wherein the denier per filament in the bicomponent multifilament yarn ranges from about 1.0 to about 3.5.

The elastic fabric of any one of (aspects 1 to 8), wherein the ratio of the first component to the second component is from about 30:70 to about 70:30.

The elastic fabric of any one of (aspects 1 to 9), wherein the filaments have a cross-section with an aspect ratio of 1.5:1 or greater.

The elastic fabric of any one of (aspects 1 to 10), wherein the cross-section of the filaments is selected from a circle, oval, snowman, or ribbon.

The elastic fabric of any one of (aspects 1 to 11), wherein the crimp contraction is from about 0.5% to about 10%.

The elastic fabric of any one of (aspects 1 to 12), wherein the crimp potential is from about 40 CP 40% to about 70%.

The bicomponent multifilament yarn of any one of (aspects 1-13), having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament are independently selected and differ in at least one of (a) denier per filament, (b) ratio of the first component of the filaments to the second component of the filaments, (c) cross section, and (d) combinations thereof.

A method for preparing the bicomponent multifilament yarn of any one of (aspects 1-14), the bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament differ in at least one of (a) a ratio of a first component of the filaments to a second component of the filaments, (c) a cross section, and (d) a combination thereof, the method comprising extruding a polymer comprising the first component and the second component of each filament through separate holes in a spinneret, wherein (a) the holes differ in size, (b) the holes differ in cross section, (c) the first component and the second component have different ratios within each of the holes, and (d) a combination thereof.

A method for preparing a bicomponent multifilament yarn according to any one of (aspects 1-15), the bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament have a partial overlap of the same characteristics which may be selected from (a) denier per filament, (b) ratio of the first component of the filaments to the second component of the filaments, (c) cross section, and (d) combinations thereof, wherein both first and second are combined into a single multifilament yarn by entanglement, twist or jet texturing process.

A bicomponent multifilament yarn according to any one of aspects (1) to (16), comprising poly (ethylene terephthalate) and poly (propylene terephthalate), wherein the bicomponent filament has a substantially oval cross-sectional shape with an aspect ratio a: B of about 2:1 to about 5:1, wherein a is the fiber cross-sectional major axis length and B is the fiber cross-sectional minor axis length, a polymer interface substantially perpendicular to the major axis, and a cross-sectional configuration selected from the group consisting of side-by-side and eccentric sheath-core.

An elastic fabric according to any one of (aspects 1 to 17) comprising a bicomponent multifilament yarn comprising 2GT/3GT, wherein the crimp potential is from about 40% to about 70% and the crimp contraction is from about 0.5% to about 8%.

An elastic fabric according to any one of (aspects 1 to 18) comprising a bicomponent multifilament yarn comprising 2GT/3GT, wherein the crimp potential is less than about 60% and the crimp contraction is from about 0.5% to about 6%.

Examples

Example 1A-multifilament bicomponent yarn was produced by melt spinning to have a total denier of 50.7. This yarn consisted of 34 filaments. CP 67 and CS 8.5. The polymer ratio of each filament was 60% poly (ethylene terephthalate) (PET) and 40% poly (propylene terephthalate) (PTT). The total elongation at break was 22% and the fracture toughness was 4.3 g/denier. The 34 individual filaments, which make up a total of 50.7 denier, have different deniers ranging from 1.2 denier to 2.0 denier. Standard spin finish was applied at 2.0% w/w to ensure good package formation and control of friction and static electricity during the subsequent knitting and weaving process.

Example 1 AC-a multifilament bicomponent yarn was produced according to the process of example 1A, wherein 34 filaments were all 1.5 dpf (denier per filament).

Example 2-multifilament yarns of examples 1A and 1AC were knitted on a circular knitting machine, then dyed and finished with disperse dyes in a conventional manner.

Example 3-multifilament yarns of examples 1A and 1AC were each individually wrapped with 50 denier 72 filament Draw Textured Yarn (DTY) (in this case DTY polyester yarn) and knitted on a circular knitting machine, then dyed and finished with disperse dye in a conventional manner. Fabrics containing 1A yarns are significantly softer and have better drape (i.e., how the fabric sags under its own weight). DTY is also known as crimped yarn.

Example 4F-multifilament bicomponent yarn was produced by melt spinning to have a total denier of 50. This yarn consisted of 46 filaments. CP is 50 and CS is 5.0. The polymer ratio for each filament was 60% poly (ethylene terephthalate) and 40% poly (propylene terephthalate). Standard spin finish was applied at 2.0% w/w to ensure good package formation and control of friction and static electricity during the subsequent knitting and weaving process. Multifilament bicomponent yarns are knitted on circular knitting machines. It is dyed in a conventional manner using disperse dyes and dried at 140 ℃ on a tenter frame. The fabric has a soft hand and desirable drape.

Claims (19)

1. An elastic fabric comprising a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament are independently selected and differ in at least one of the following aspects: (a) denier of the monofilament; (b) the ratio of the first component to the second component of the filament; (c) the cross-section; and (d) a combination 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 knitted or woven elastic fabric. 5. The elastic fabric of claim 1, wherein the denier of the bicomponent multifilament yarn is from about 20 to about 150. 6. The elastic fabric of claim 1, wherein the first and second components of the bicomponent yarn comprise polyesters selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. 7. The elastic fabric of claim 1, wherein the denier of the monofilament in the bicomponent multifilament yarn ranges from about 0.8 to about 4.0. 8. The elastic fabric of claim 1, wherein the denier of the monofilament in the bicomponent multifilament yarn ranges from 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 an aspect ratio of 1.5:1 or greater. 11. The elastic fabric of claim 1, wherein the cross-section of the filament is selected from circular, oval, snowman-shaped, or ribbon-shaped. 12. The elastic fabric of claim 1, wherein the crimp shrinkage rate is from about 0.5% to about 10%. 13. The elastic fabric of claim 1, wherein the crimp potential is from about 40% to about 70%. 14. A bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament are independently selected and differ in at least one of the following aspects: (a) denier of the monofilament; (b) the ratio of the first component to the second component of the filament; (c) cross-section; and (d) a combination thereof. 15. A method for preparing a bicomponent multifilament yarn having at least a first bicomponent filament and a second bicomponent filament, wherein the first filament and the second filament differ in at least one of the following aspects: (a) denier of the monofilament; (b) the ratio of the first component to the second component of the filament; (c) cross-section; and (d) a combination thereof, the method comprising extruding a polymer comprising the first component and the second component of each filament through separate orifices in a spinneret; wherein (a) the orifices differ in size; (b) the orifices differ in cross-section; (c) within each of the orifices, the first component and the second component have different ratios; and (d) a combination thereof. 16. A method for preparing bicomponent multifilament yarn, wherein a first bicomponent filament is prepared by selecting one or more of the following characteristics: (a) denier of the filament; (b) the ratio of the first component to the second component of the filament; (c) cross-section; and (d) a combination thereof; and a second bicomponent filament is prepared using one or more of the following characteristics: (a) denier of the filament; (b) the ratio of the first component to the second component of the filament; (c) cross-section; and (d) a combination thereof; wherein the first bicomponent multifilament yarn and the second bicomponent multifilament yarn are combined into a single multifilament yarn by entanglement, twisting, or air-jet texturing processes. 17. A bicomponent multifilament yarn comprising polyethylene terephthalate and propylene terephthalate, wherein the bicomponent filaments have: a generally oval cross-sectional shape having an aspect ratio A:B of about 2:1 to about 5:1, wherein A is the length of the long axis of the fiber cross-section and B is the length of the short axis of the fiber cross-section; a polymer interface substantially perpendicular to the long axis; and a cross-sectional configuration selected from the group consisting of: side-by-side and eccentric skin-core. 18. An elastic fabric comprising a bicomponent multifilament yarn comprising 2GT/3GT, wherein the crimp potential is from about 40% to about 70% and the crimp shrinkage is from about 0.5% to about 8%. 19. An elastic fabric comprising a bicomponent multifilament yarn comprising 2GT/3GT, wherein the crimp potential is less than 60% and the crimp shrinkage is from about 0.5% to about 6%.