DESC:FIELD OF INVENTION
The present invention relates to coated woven fabrics and more particularly, to a leather-like woven denim fabric, a method of manufacturing the same and denim garments thereof.

BACKGROUND OF THE INVENTION
Fabric coating is a method of applying a layer of appropriate compound on one or both the sides of the fabric. There are various types of polymers used for coating the fabric such as Polyvinyl Chloride, Polyvynilidene chloride, Styrene Butadine Rubber and the like. There are different types of coating methods such as Direct coating, Transfer coating, Mayer Rod coating, Calender coating and the like. The coated fabrics are used in fields of agriculture, apparel, medical, industrial and the like.

Presently, coated fabrics available in market include acrylic and polyurethane based coatings, with or without silicon softener. However, such coatings are available in the paste form as shown in FIG. 1 wherein a paste (20) is applied to a woven fabric (10). Drawback of the paste coating technique is that only a limited amount of coating can be applied on a woven fabric at a time thereby limiting the thickness of the coating over the fabric. If a thicker coating layer is desired, then the woven fabric must be paste coated twice or thrice. However, repeated paste coating deteriorates the physical properties of the woven fabric including the feel of the fabric causing discomfort to a wearer. Further, repeated coating increased the cost of manufacturing of the coated fabric. Therefore, a leather feel on the woven fabric is not achievable and advisable by using paste coating methods.
Accordingly, there is a need for reliable method to manufacture woven fabrics, including woven denim fabrics, to provide a leather-like feel/texture to the woven fabric or woven denim fabric.

SUMMARY OF THE INVENTION
The present invention relates to a leather-like woven denim fabric and a method of manufacturing thereof. In the first step, a woven denim fabric is provided to a coating assembly wherein a foam of a predefined composition is applied to the woven denim fabric to form a layer thereon thereby forming a foam coated woven denim fabric having uniformly loaded foam. In next step, the foam coated woven denim fabric is dried to a temperature from about 100o C to about 150o C. In the next step, the foam on the foam coated woven denim fabric is crushed thereby forming a uniformly coated woven denim fabric. In the next step, the coated woven denim fabric is calendar processed at a predefined temperature and pressure. In the last step, the coated woven denim fabric undergoes curing at a temperature from about 150o C to 170o C to provide a leather-like woven denim fabric. The composition of foam can be defined based on the thickness required on the fabric and comprises 80-95% of polyurethane based on the thickness required on the fabric, 1 – 1.5% of ammonia, 1 – 5% of fixer and remaining percentage amount is water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows paste coating of a fabric in accordance with prior art;
FIG. 2 shows a coating process in accordance with an embodiment of the present invention; and
FIG. 3 shows a fabric being passed through coating assembly FIG. 2.

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 to a particular structure of the invention selected for illustration in the drawings and are not intended to define or limit the scope of the invention.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.
All materials used herein were commercially purchased as described herein or prepared from commercially purchased materials as described herein.
In accordance with an embodiment, the present invention relates to a leather-like woven denim fabric, a process of manufacturing a leather-like woven denim fabric by foam coating said woven denim fabric and the garments thereof. The leather-like woven denim fabric comprising a woven denim fabric having a layer of polyurethane on front and/or back side of the woven denim fabric giving a leather-like feeling to the fabric. In accordance with an embodiment, the woven denim fabric is manufactured with warp and weft yarn. Both the yarns are either made of natural or man-made fibers or combination thereof. The woven denim fabric may be one way stretchable or two-way stretchable or non-stretchable. The warp yarn count ranges from 6‘s Ne to 40’s Ne; more particularly, 10’s Ne to 20’s Ne. the weft yarn count ranges from 10’s Ne to 40’s Ne and can be woven with any denim weave such as 3/1 twill, 2/1 twill or any weave. The fabric is dyed with indigo or Sulphur or combination of both the dyes. The woven denim fabric weight is ranges from 5 Oz. / sq. yds. To 14 Oz. / sq. yds. According to the present invention, the amount of polyurethane based on the thickness of the leather-like denim woven fabric is from about 40 gm to about 150 gm per meter of the fabric.
The coating process provide herein for woven denim fabrics and/or garments thereof comprising foam coating of said woven denim fabric and/or garments thereof. The manufacturing processes described herein provide the leather feel and look to denim fabric, while also rendering the fabric air permeable and comfortable to the wearer.

Referring to FIGS. 2-3, in one more aspect provided herein is a method for manufacturing a leather-like woven denim fabric. In this method, initially a woven denim fabric (100) is provided. After fabric manufacturing, the woven denim fabric (100) undergoes various pre-treatment stages comprising desizing, scouring, bleaching, dyeing, printing and the like. The woven fabric (100) is coated on the opposite side of print or both side. The woven denim fabric (100) may be either stretch or non-stretch, made from natural fibre or regenerated fibre or man-made fibre or a combination thereof. The pre-treated woven denim fabric (100) then undergoes coating processes.
In the next step, a foam composition comprising a polyurethane as an active ingredient is applied to form a layer on the woven denim fabric (100). The foam composition is applied to the woven fabric (100) by passing the woven denim fabric (100) through a coating unit (107). The coating unit (107) receives the fabric from a fabric guide roll (102) that guides the fabric to pass through the coating unit (107).
The woven denim fabric (100) is foam coated on either the front side or the back side. The woven fabric (100) is passed through coating unit (107) shown in FIG. 2. The gap (107C) between the coating blade (107A) and the coating rollers (107B) is set in such a way that the woven denim fabric (100) is passed smoothly on the coating rollers (107B) thereby allowing for uniform deposition of the foam on the woven fabric (100) thereby forming a foam coated woven denim fabric. The woven fabric (100) is adjusted with adequate tension throughout the process to get a uniform foam coat (loading) on to the woven denim (100) and prevent slackening of the woven fabric (100) on the machine.
The level of the foam bath is maintained at a constant height during the foam coating process. A foam generator (Not Shown) attached to the machine generates (Not shown) foam which is fed continuously on to the woven denim fabric (100) via a foam supply tube (Not shown), and the foam is applied on the surface of the fabric (100) by a foam coating blade (107A). The foam is applied on the woven denim fabric (100) on such a way that foam does not collapse. In an embodiment, the foam coating composition comprises 80-95% of polyurethane, 1 – 1.5% of ammonia, 1 – 5% of fixer and the remaining percentage amount (out of 100%) is water. Color may be added to the coating composition as per the requirement. It is to be noted here that the amount of polyurethane depends on the desired coating, if more loading is required the amount of polyurethane is increased and vice versa. In other words, the amount of the polyurethane depends on the thickness of the coating required over the leather-like woven denim fabric. The coating composition is made in such a way that the foam comprises a substantially uniform bubble size and uniform density. In this one embodiment, the foam density is 150 to 250 gm per litre. However, it is understood here that the coating density may vary in alternative embodiments of the present invention depending on the thickness required.
In accordance with this one embodiment, in the next step, the layer applied coated fabric (100) is dried. The foam coated woven denim fabric (100) received from the coating assembly (107), is thereafter passed to a drying zone (103). The foam coated woven denim fabric (100) is dried at the temperature from about 100o C to about 150° C.
In the next step, the foam is crushed on the fabric (100) for a uniformly loaded coat on the fabric thereby forming the coated woven denim fabric (200). This step is carried out by passing the foam coated woven denim fabric (100) through a crushing zone (104) comprising a pair of rollers that crush the foam on the fabric (100) thereby forming a uniformly loaded coat on the fabric (100). In this one embodiment, the crushing zone (104) includes at least two rolls; a top roller (105) and a bottom roller (106) arranged in a predefined configuration. The bottom roller (106) is made of rubber and the top roller (105) is made of steel. The surface of the top roller (105) is either smooth or engraved, to get a smooth or patterned effect on the coated woven denim fabric (100) along with crushing of the foam. The foam coated woven denim fabric (100) is pressed between the two rollers (105, 106) wherein foam gets crushed forming the uniform coated woven denim fabric (200) which is then wound on a roll (109). However, it is understood here that number, material and configuration of the rolls (105, 106) may vary in alternative embodiments of the present invention and A person skilled in the art can easily arranged the rollers and hence not explained in detailed here.
In the next step, the coated woven denim fabric (200) is passed through a calendaring device (Not Shown). In this one embodiment, the calendaring of the coated woven denim fabric (200) takes place at room temperature and at a pressure of 150-300 N to get a shine on the fabric. However, it is to be noted here that the temperature and pressure of the calendaring device may vary in alternative embodiments of the present invention.
In the next step, the coated woven denim fabric (200) is cured on a stenter / polymerizer machine at the temperature from about 150o C to about 170 ° C. The stenter machine adjusts the length and width of the coated woven denim fabric (200) to pre-determined dimensions and also allows for thermal fixation of the coated fabric thereby forming a leather-like woven denim fabric. The coated woven denim fabric (200) is typically stretched width wise to maintain a uniform width. However, it is understood here that temperature and pressure ranges may vary in alternative embodiments of the present invention.
The garment made from the leather-like coated woven denim fabric can be subjected to a denim stone or heavy washing process for abrading coated portion of the leather-like woven denim fabric in order to get a base colour of woven denim without deterioration of the fabric and leather like feeling of the fabric.
The processes of the present application allow to form a required thickness of the coating layer on one side of the fabric in a single step without deteriorating quality of the woven denim fabric and provides a leather-like (look and feel) denim woven fabric. Further, the processes claimed herein reduce manufacturing costs while concomitantly providing a cheaper alternative to leather and/or a different leather-like look and feel to denim woven fabric.
Hereinafter, the present invention will be described in more detail based on examples. The examples are not intended to limit the scope of the present invention. It is believed the invention will be better understood from the following detailed examples:
Example 1:
A leather-like denim fabric was made as per the method claimed in the application and tested for apparel purpose. Further, the garment made from the leather-like coated woven denim fabric has subjected to the denim washing process so as to coated portion abraded during stone or heavy wash and base colour of woven denim fabric (100) to come out. Following were the parameters of the denim-like woven denim fabric:
Warp : 16‘s Ne
Weft : 150 + 70 D Elastane
EPI * PPI : 100 * 55
Weave : 3/1 Twill

Table 1
Product (#54742) Strength (pound) Weight (Oz. per Sq. Yd.) % stretch Rubbing fastness
Tear Tensile Un wash Wash Dry Wet
Warp Weft Warp Weft
Product with coating 8.8 9.2 132 110 7.5 8.5 55% 3 1
Norms
(GAP) 7 5.5 110 70
allowance ± 5% allowance ± 10% 3 1

The experiments were conducted to check tear strength and tensile strength of the leather-like coated woven denim fabric (200). Referring Table 1, test result of coated product (the product has been numbered as ‘54742’) with comparison of standard norms of GAP brand are shown. The tear strength of leather-like coated woven denim fabric (54742) was warp way approximately 8.8 lb and weft way approximately 9.2 lb whereas the product acceptance norms for GAP in tear strength on warp and weft way are 7 lb and 5.5 lb respectively. Tensile strength of leather-like coated woven denim fabric (54742) was warp way approximately 132 lb and weft way are approximately 110 lb whereas acceptance norms of GAP in warp way and weft way are 110 lb and 70 lb respectively.
The denim garment leather-like woven denim fabric had leather like feeling. Further, test proved that the strength of the woven denim fabric was not deteriorated due to the coating process as claimed.
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.

,CLAIMS:
1. A method for manufacturing a leather-like woven denim fabric comprising steps of:
providing a woven denim fabric to a coating assembly;
applying a foam of a predefined foam composition to form a layer on the woven denim fabric thereby forming a foam coated woven denim fabric having uniformly loaded foam;
drying the foam coated woven denim fabric;
crushing the foam on the foam coated woven denim fabric thereby forming a uniformly coated woven denim fabric;
subjecting the coated woven denim fabric to calendaring process a predefined temperature and pressure; and
curing the coated woven denim fabric to obtain a leather-like woven denim fabric.

2. The method of manufacturing a leather-like woven denim fabric as claimed in claim 1, wherein the foam coated woven denim fabric is dried at the temperature from about 100o C to about 150° C.

3. The method of manufacturing a leather-like woven denim fabric as claimed in claim 1 or 2, wherein the foam of the composition has a substantially uniform bubble size and foam density from about 150 to about 250 gm per litre.

4. The method of manufacturing leather-like woven denim fabric as claimed in one of the preceding claims 1-3, wherein the step of calendaring the coated woven denim fabric is carried out at a pressure from about 150 to about 300 N and preferably at a room temperature.

5. The method of manufacturing leather-like woven denim fabric as claimed in one of the preceding claims 1-4, wherein the coated woven denim fabric is cured at the temperature from about 150o C to about 170° C.

6. The method of manufacturing leather-like woven denim fabric as claimed in one of the preceding claims 1-5, wherein the predetermined foam composition depends upon a thickness of coating to be form on the fabric and comprises 80-95% of polyurethane depending upon thickness to be formed, 1 – 1.5% of ammonia, 1 – 5% of fixer and remaining percentage amount is water.

7. The method of manufacturing leather-like woven denim fabric as claimed in as claimed in one of the preceding claims 1-6, wherein the denim fabric is made up of natural fibres, man-made fibres or combination of natural and manmade fibres.

8. The method of manufacturing leather-like woven denim fabric as claimed in claim 1 or 7, wherein the denim fabric is woven with warp and weft yarn having warp yarn count from about 6s Ne to about 40s Ne and weft yarn count from about 10s Ne to about 40s Ne.

9. The method of manufacturing leather-like woven denim fabric as claimed in claim 1 or 7, wherein the denim fabric is woven with warp and weft yarn having warp yarn count from about 10s Ne to about 20s Ne and weft yarn count from about 10s Ne to about 40s Ne.

10. The method of manufacturing leather-like woven denim fabric as claimed in one of the preceding claims1 and 7-9, wherein the denim fabric is stretchable or non-stretchable.

11. The method of manufacturing leather-like woven denim fabric as claimed in one of the preceding claims1 and 7-10, wherein the coated denim fabric weight from about 5 oz / sq. yds. to about 14 oz./ sq. yds.

12. A leather-like denim woven fabric manufactured by a method as claimed in one of the preceding claims 1-11, comprising a woven denim fabric having a layer of polyurethane on front and/or back side of the woven denim fabric giving a leather-like feeling to the fabric wherein the polyurethane based on the thickness is from about 40 gm to about 150 gm per meter of the leather-like denim woven fabric.