DESC:FIELD OF INVENTION
This disclosure is related to a method for processing a four-way stretch fabric.
BACKGROUND OF THE INVENTION
The early versions of stretch fabrics incorporated a one-way stretch, i.e., stretching in either the weft direction or the warp direction. The newer versions of stretch fabrics allow for stretching along the weft as well as the warp directions, i.e., a four-way stretch.
One way stretch fabrics are easy to process in a continuous process where the stretch is possible only in the warp or only in the weft direction. By comparison, continuous processing of four-way stretch fabrics is challenging because there is a possibility of excess stretch in the warp direction during conventional continuous processing. During continuous processing of four-way stretch fabrics, the fabric tension in the warp direction is high enough that it is often observed that it kills the warp stretch of the fabric, and later it is difficult to regain the warp way stretch.
Therefore, there is a need in the field for improved methods for processing four-way stretch fabrics.

SUMMARY OF THE INVENTION
Described herein is a method for wet processing of four-way stretch fabrics and/or garments made from four-way stretch fabrics. The fabric is woven with warp and weft yarns, which are elastomeric yarns and the four-way stretch fabrics described herein provide about 25% to about 50% stretch in the weft and warp directions.
Provided herein is a method of processing four-way stretch fabrics and apparel thereof, said method comprising the steps of:
providing a four-way stretch fabric;
removing protruding fibers on the fabric by singeing followed by de-sizing the fabric and removing impurities therefrom by washing;
pre-treating the fabric by continuous scouring;
mercerising the fabric by contacting the fabric with alkaline solution;
wet-relaxing the fabric and drying the fabric;
stentering the fabric;
dyeing the fabric;
relax drying, and finishing the fabric; and
sanforising the fabric.
DETAILED DESCRIPTION OF THE INVENTION
Although specific terms are used in the following description for sake of clarity, these terms are intended to refer only illustration, and are not intended to define or limit the scope of the invention.
The following description is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
References in the specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
Described herein are methods for manufacture of four-way stretch fabrics. Four-way stretch fabrics typically comprise a single or dual core elastomeric yarn comprising elastomeric filament(s) as core with either synthetic fibers, cellulosic fibers, natural fibers or blend thereof (e.g., cotton) twisted around the elastomeric core filament. An elastomeric strand/filament is one which has an elongation at failure in excess of 100% and which will return to substantially its original unstressed length after elongation to less than the break-elongation. Suitable elastomeric strands/filaments are well known and include, for example, both natural rubber and polyether-polyurea copolymer (Spandex®), polyurethane (Elastane®) fibers/yarns/filaments. The fibers of present invention may include synthetic fibers and/or natural fibers. The synthetic fibers include and are not limited to polyesters, such as Nylon, Aramid, Modacrylic, regenerated cellulosic and the like. The natural fibers include and are not limited to cotton, linen or a combination thereof. Cellulosic fibers include cotton, jute, silk, viscose rayon and the like.
Elastomeric yarns impart a defined stretch, matched to the garment and the wearer, provide snap-back (elastic recovery) and dimensional stability, and preserve the stretchability and elastic recovery of the garment over the entire useful life of the garment.
Accordingly, the present invention provides a method of processing four-way stretch fabrics and apparel thereof, said method comprising the steps of:
providing a four-way stretch fabric;
removing protruding fibers on the fabric by singeing followed by de-sizing the fabric and removing impurities therefrom by washing;
pre-treating the fabric by continuous scouring;
mercerising the fabric by contacting the fabric with alkaline solution;
wet-relaxing the fabric and drying the fabric;
stentering the fabric;
dyeing the fabric;
relax drying, and finishing the fabric; and
sanforising the fabric.
In an initial step, providing a four-way stretch fabric includes weaving a four-way stretch fabric with warp and weft yarns having plurality of elastomeric yarns. Alternatively, the fabric can be weaved with warp and weft yarns having plurality of elastomeric yarns at other place and process according to the present invention.
In the next step, protruding fibers on the fabric are removed by singeing followed by de-sizing the fabric and removing impurities therefrom by washing. In the context of the present invention, the de-sizing is an oxidative de-sizing. In other embodiments the de-sizing may be enzymatic de-sizing, or acid de-sizing. The fabric is washed to remove the impurities from the de-sizing process.
In next step, the fabric is scoured and optionally bleached continuously to obtain the desired texture and color. In further step, mercerizing of the fabric is facilitated by contacting the fabric with alkaline solution wherein treatment with an alkaline solution (e.g., sodium hydroxide) changes the texture of cellulosic fibers/yarns, e.g., from a ribbon like fiber to a rod like structure in the fiber to obtain the desire luster and/or dimensional stability. In some embodiments, mercerization is carried out for fabrics/fibers/yarns comprising at least 40% cellulosic fibers.
In further step, wet-relaxing is typically carried out in an AIRO® machine, wherein the fabric is 60% wetted, optionally with a composition comprising a relaxing agent, followed by drying, which allows for recovery of any elasticity / stretchability that may have been lost during earlier processing steps. An AIRO® machine is based on air-only fabric transport that can deliver a strong and delicate action at the same time, and the high speed crashing of the material against a special grid, which provides a mechanical and permanent effect of softening and natural compaction of the fibers/fabric. In some embodiments, the fabric is passed through an AIRO® machine in about 60% wetted condition. In other embodiments, the fabric is passed through a relax dryer in about 60% wetted condition with an over feed of about 30 % to about 60%.
In next step, the fabric is subjected to stentering and after stentering, the fabric is optionally heat treated to bring the length and width to pre-determined dimensions. In some embodiments, the stentering is carried out at about 180 oC with a dwell time of 45 sec to obtain thermo-dimensional-stability
In further step, in one embodiment, the dyeing and/or printing with vat dyes is carried out with a PDPS (Pad-Dry-Pad-Steam) system. In another embodiment, the dyeing and/or printing with reactive dyes is carried out with a PDPS method, or a Cold Pad Batch (CPB) method for a cotton/elastomeric blend. In a further embodiment, for synthetic/cotton/elastomeric fabrics dyed with disperse vat or disperse reactive methods, a thermosol method is used for dyeing of the fabric. Alternatively, rotary screen prints may be used with pigment, vat, reactive or disperse dyes depending on the nature of the fabric.
In the context of the present invention, the PDPS method is a continuous method where the fabric is padded with a dye solution and goes to a dryer for drying, then the fabric is padded with a fixing chemical, steamed and finally washed and dried. The CPB method is a semi-continuous method where cold brand reactive dye is used, the fabric is padded with dyes in alkaline condition then goes for a rotation for 8 to 12 hr, and then washed and dried.
In next step, the dyed fabric is subjected for relax drying in a relax dryer, wherein a desired finish is applied to the fabric, e.g., a soft finish, an antimicrobial finish, an oil repellant, a water repellant and the like.
In last step, after finishing, the fabric is sent to the sanforiser machine in a relaxed condition in a layer on layer form and not in roll form. In this step, the fabric is fed into the sanforizing machine and stretched and shrunk till a predetermined length and width is achieved, thereby reducing any shrinkage which occurs after washing.
In some embodiments of the method describe herein, the fabric comprises from about 80 to about 120 ends per inch (EPI), and from about 40 to about 80 picks per inch (PPI). In some of such embodiments, the yarn comprises cotton or cotton blends with synthetic material (e.g., polyester yarns), from about 90 – 95% of the total weight of the fabric, and elastane (polyurea or polyether-polyurea copolymer). In some embodiments the fabrics produced by the method described above produce a stretch of about 15% – 35% in the warp direction and a stretch of about 15% – 40% in the weft direction with growth of about 3% - 7% and dimensional stability (shrinkage) below 3%. In some embodiments, the linear mass density of elastane used in the elastomeric yarns of the fabrics described above is from about 40D to about 140 D, or from 60 D to about 110 D. In some embodiments, the thread count for cotton in the fabric ranges from about 10s Ne to about 40s Ne.
EXAMPLES
The following examples and comparative examples are provided to demonstrate particular embodiments of the present invention. It should be appreciated by those skill in the art that the methods disclosed in the examples and comparative examples that follow merely represent exemplary embodiments of the present invention. Those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments described and still obtain a like or similar result without departing from the spirit and scope of the present invention.

AATCC Test Method 135: Dimensional Change of Fabrics after Home Laundering.
Scope: Determines the dimensional changes of garments when subjected to home laundering procedures used by consumers.
ASTM D3107: This test method is used to determine the stretch, growth and recovery properties that garments made with the fabric tested may be expected to exhibit during use.

Example 1: 275 grams per square meter (gsm) four-way stretch fabric
Construction: Ends per inch (EPI): 112, Picks per inch (PPI): 66, Yarn: both warp and weft: 20s Ne + 105 D elastane,
Weave: 2/1 Twill, Blend: 92% cotton/8% elastane,
The fabric was processed according to step (1) – (8) above. A 25% stretch (as per ASTM D-3107) was achieved in warp and weft directions with a growth (as per ASTM D-3107) of 4% and Dimensional Stability (shrinkage) below 3% in both directions as per AATCC-135 Line Dry 1 Wash.

Example 2: 275 gsm four-way stretch fabric
Construction: EPI: 84, PPI: 50, warp: 2/30s Ne + 70 D elastane, weft: 16s Ne+ 70 D elastane,
Weave: 2/1 Twill, Blend: 95% cotton/5% elastane,
The fabric was processed according to step (1) – (8) above. A 25% stretch (as per ASTM D-3107) in warp and a 28% stretch in weft was achieved with a growth (as per ASTM D-3107) of 5% and Dimensional Stability (shrinkage) below 3% in both directions as per AATCC-135 Line Dry 1 Wash.

Example 3: 294 gsm four-way stretch fabric
Construction: EPI: 84, PPI: 50, warp: 40Ne + 40 D elastane, weft: 16s Ne+ 105 D elastane,
Weave: 4/1 Satin, Blend: 92% cotton/8% elastane,
The fabric was processed according to step (1) – (8) above. A 16% stretch (as per ASTM D-3107) in warp and 28% weft with a growth (as per ASTM D-3107) of 3% in warp and 5% in weft was achieved and Dimensional Stability (shrinkage) below 3% in both directions as per AATCC-135 Line Dry 1 Wash.

Example 4: 235 gsm four-way stretch fabric
Construction: EPI: 112, PPI: 68, warp: 20Ne + 105 D elastane, weft: 30s Ne+ 70 D elastane
Weave: 2/1 Twill, Blend: 95% cotton/5% elastane,
The fabric was processed according to step (1) – (8) above. A 23% stretch (as per ASTM D-3107) in warp and 36% stretch in weft was achieved with a growth (as per ASTM D-3107) of 4% in warp and 6% in weft and Dimensional Stability (shrinkage) below 3% in both directions as per AATCC-135 Line Dry 1 Wash.
The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This device or unit or arrangement of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment.
It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively.
,CLAIMS:
1. A method of processing four-way stretch fabrics and apparel thereof, said method comprising the steps of:
providing a four-way stretch fabric;
removing protruding fibers on the fabric by singeing followed by de-sizing the fabric and removing impurities therefrom by washing;
pre-treating the fabric by continuous scouring;
mercerising the fabric by contacting the fabric with alkaline solution;
wet-relaxing the fabric and drying the fabric;
stentering the fabric;
dyeing the fabric;
relax drying, and finishing the fabric; and
sanforising the fabric.
2. The process as claimed in claim 1, wherein the fabric provides from about 25% to about 50% stretch in both the weft and the warp directions.
3. The process as claimed in claim 1, wherein the four-way stretch fabric comprises single or dual core elastomeric yarns.
4. The process as claimed in claim 3, wherein the elastomeric yarn comprises single or dual core elastomeric filament with synthetic fibers, cellulosic fibers, natural fibers or blend thereof twisted around the said core elastomeric filament.
5. The process as claimed in claim 4, wherein the core elastomeric filament comprises rubber, polyether-polyurea copolymer, polyurethane, or a combination thereof.
6. The process as claimed in claim 4, wherein the synthetic fibers includes polyester, nylon, re-generated cellulosic or a combination thereof.
7. The process as claimed in claim 4, wherein the natural fibers comprising cotton, linen or a combination thereof.
8. The process as claimed in claim 1, wherein the de-sizing is an oxidative de-sizing, an enzymatic de-sizing, or an acid de-sizing.
9. The process as claimed in claim 1, wherein the step pre-treating the fabric is optionally followed by bleaching of the fabric.
10. The process as claimed in claim 1, wherein the mercerization is carried out where the fabric comprises at least 40% cellulosic fibers.
11. The process as claimed in claim 1, wherein the wet relaxing is such that the fabric is 60% wetted, optionally with a composition comprising a relaxing agent.
12. The process as claimed in claim 1, wherein the stentering is optionally followed by heat setting of the fabric.
13. The process as claimed in claim 1, wherein dyeing of the fabric is facilitated with a vat dye using a Pad-Dry-Pad-Steam (PDPS) system or thermosol method.
14. The process as claimed in claim 1, wherein dyeing of the fabric is facilitated with a reactive dye using either a PDPS method, a Cold Pad Batch (CPB) method or thermosol method.
15. The process as claimed in claim 1, the shrinkage of the finished fabric is below 3% in both weft and warp directions.
16. The process as claimed in claim 1, wherein the growth of the finished fabric is 3% to 5% in both directions.
17. The process as claimed in claim 1, the fabric provides stretch in a range from about 15% to about 35% in the warp direction.
18. The process as claimed in claim 1, the fabric provides stretch in a range from about 15% to about 40% in the weft direction.
19. The process as claimed in claim 1, the fabric comprises from about 80 to about 120 ends per inch (EPI).
20. The process as claimed in claim 1, the fabric comprises from about 40 to about 80 picks per inch (PPI).