DESC:FIELD OF THE INVENTION
The present invention relates to water-resistant fabrics. Particularly, the present invention relates to a method of making an anti-microbial, breathable water-resistant fabric and a water-resistant fabric thereof.

BACKGROUND ART OF THE INVENTION
Breathable fabrics are a type of fabrics particularly useful for garments used in humid and wet environments. Breathable fabrics aid in transfer of water vapor and have become important in a wide number of applications in textile related products. A breathable fabric with a polymer membrane provides an improved level of comfort for the wearer, while preventing excess moisture from penetrating into the interior of the garment. Various types of waterproof fabrics are available in the market. Waterproof fabrics are woven or non-woven or knit fabrics that are inherently, or have been treated to become, resistant to penetration by water and wetting. They are usually natural or synthetic fabrics that are laminated to or coated with a waterproofing material.
Currently available breathable fabrics are susceptible to growth of microorganisms that ultimately damage the fabric or bad odors. These fabrics are particularly susceptible to the growth of microorganisms when a garment is worn for an extended period in extremely moist and dirty environments.
Presently, waterproofing chemicals such as rubber, polyvinylchloride (PVC), polyurethane (PU), silicone, wax coated on or within the fabric using solvents including toluene, xylene, methyl ethyl ketone (MEK), and di-methyl formamide (DMF), dioctyl phathalate, methyl isobutyl ketone etc. However, the exhaust fumes from solvent based methodes pollute the environment. Further, these solvents can pose a drinking water hazard if they accumulate in ground water. Further, the fumes from solvent based coating are harmful to human health as such fumes affect the respiratory system of humans. The common health hazards associated with exposure to solvents is dermatitis or eczema with contact dermatitis developing from just a single exposure or after multiple exposures. The same could also leave the skin susceptible to a short-term infection or to a chronic condition. Exposure can also result in sensitization to the solvent, which is a delayed allergic reaction that often becomes more severe with subsequent exposures and can lead to a lifelong chronic condition. Depending on the type and concentration of the solvent, exposure effects can range from mild respiratory irritation to severe damage to body organs and systems. In extreme cases, overexposure to solvent vapors can cause respiratory failure and death.
Hence, there is need for a method for preparing a water-resistant fabric where the fabric is prepared by a safe method that alleviates at least some of the drawbacks of the prior art.
SUMMARY OF THE INVENTION
Accordingly, the present invention in one aspect provides a method for the manufacturing of a water-resistant fabric. The method comprises of a base fabric having an outer surface and an inner surface. The outer surface of the base fabric is coated with a water-resistant coating composition. The inner surface of the base fabric includes a multilayered aqueous based coating. In an embodiment, the inner surface of the base fabric is coated with two layers. A first inner layer is an aqueous based polyurethane layer. The first inner layer is then coated with a second inner layer that is embedded with nanometal particles having an anti-microbial property. According to the preferred embodiment, the second inner layer is an aqueous polyurethane matrix having nano-silver particles embedded on to its surface, wherein the second inner layer is in contact with the wearer’s skin.
In another embodiment, a water-resistant fabric in accordance with the present invention is disclosed. The fabric comprises of a base fabric having an inner surface and an outer surface. The outer surface is coated with a water-resistant coating. The inner surface is coated with a first inner layer, and the first inner layer is further coated with a second inner layer embedded with nanometal particles.
In an embodiment of both aspect of the invention, the base fabric is woven, non-woven or a knitted fabric and is made of natural or man-made fibers including polyester, nylon, p-aramid, m-aramid and combination thereof.
As per another embodiment of both aspect of the invention, the water-resistant coating comprises a composition of about 4% to 20% of fluorocarbon water repellent and about 0.5% to 4% cross-linkers in water by weight of the coating composition.
According to the present invention, the grams per square meter (hereinafter, GSM) of the water- resistant coating composition is preferably about 2 to 10 GSM, and the GSM of the first inner layer and the second inner layer is 4 to 20 GSM.
According to the present invention, the second inner layer is embedded with nano-silver particles and comprises of aqueous polyurethane in a range of about 80 to 95% (w/w), thickening agents in a range of about 2 to 8% (w/w), curing agents in a range of about 1 to 8% (w/w) and antimicrobial agents in a range of about 0.5 to 10% (w/w) along with silica fumes in a range of about 1 to 6% (w/w) by weight of the second inner layer.

BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a cross-section view of the water- resistant fabric in accordance with a preferred embodiment of the present invention;

DESCIPTION OF THE INVENTION
Although specific terms are used in the following description for sake of clarity, these terms are intended to refer only to particular structure of the invention selected for illustration in the drawings, and are not intended to define or limit the scope of the invention.
References in the specification to “preferred embodiment” means that a particular feature, structure, characteristic, or function described in detail thereby omitting known constructions and functions for clear description of the present invention.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
In one aspect, provided herein is a method for manufacturing of a water-resistant fabric in accordance with a preferred embodiment of the present invention.
In another aspect, provided herein is a water-resistant fabric, and a method for manufacturing thereof in accordance with a preferred embodiment of the present invention.
In a preferred embodiment, the present invention provides a method for manufacturing of water-resistant fabric, said method comprising the steps of:
a) providing a base fabric (110) having an outer surface (120) and an inner surface (130),
b) coating the outer surface (120) of the base fabric (110) with a water-resistant coat (125), the water-resistant coat (125) comprising fluorocarbon water repellent in a range of about 4% to 20% (w/w) and cross-linkers in a range of about 0.5% to 4% (w/w) in water;
c) coating the inner surface (130) of the base fabric (110) with a first inner layer (135), the first inner layer (135) is an aqueous based polyurethane layer, and
d) coating the first inner layer (135) with a second inner layer (140) that is embedded with nanometal particles (145) having an anti-microbial property, the second inner layer is an aqueous polyurethane matrix having nano-silver particles embedded on to its surface and wherein second inner layer (140) being in contact with the wearer’s skin.

In accordance with a preferred embodiment of the present invention, the fluorocarbon is applied over the outer surface of the base fabric by a padding method. The fluorocarbon formulation comprises fluorocarbon water repellent in a range of about 4% to 20% (w/w and cross-linkers in a range of about 0.5% to 4% (w/w) in water.
The inner surface is coated with the first inner layer which is an aqueous based polyurethane layer. The GSM of first inner layer is between 4 GSM and 20 GSM including both. The first inner layer which is the aqueous based polyurethane layer is coated on the inner surface of the base fabric using knife coating technology to provide the water resistance from inside. The first inner layer fills the gaps of the base fabric evenly and forms a very thin film of a water-resistant layer having micro pores for moisture vapor to pass through, thereby providing water resistant and breathability to the water-resistant fabric.
The second inner layer is a polyurethane matrix having nano-silver particles embedded on to the surface for providing anti-microbial property. The GSM of the second inner layer is about 4 to 20 GSM. Advantageously, fumed silica is mixed with polyurethane matrix before coating on the first inner layer of the woven fabric. The fumed silica provides a soft and non-tacky surface thereby providing comfort to the wearer. The second inner layer is in contact with the wearer’s skin. The formulation of the second layer comprises of aqueous polyurethane in a range of about 80 to 95%(w/w), thickening agents in a range of about 2 to 8% (w/w), curing agents in a range of about 1 to 8% (w/w) and antimicrobial agents in a range of about 0.5 to 10% (w/w) along with silica fumes in a range of about 1 to 6% (w/w). Optionally, the formulation may comprise blowing agent and surfactants for achieving high moisture vapor transmission rate (MVTR).
In another preferred embodiment, the present invention provides a water-resistant fabric comprising a base fabric having an inner surface and an outer surface, a water-resistant coating on the outside of the outer surface, a first inner layer of coating on the inner surface of the base fabric and a second inner layer embedded with nanometal particles having anti-microbial property over the first inner layer, the second inner layer being in contact with the wearer’s skin.
In an embodiment, the base fabric is selected from the group consisting of woven, non-woven and knitted fabric.
In an embodiment, the base fabric is made of natural or man-made fibers including polyester, nylon, p-aramid, m-aramid and combination thereof.
In an embodiment, the water-resistant coating is selected from the group comprising of fluorocarbon coating, silicone coating, and the like.
In an embodiment, the GSM of the water- resistant coating is about 2 to 10 GSM, and the GSM of the first aqueous inner layer and the second aqueous inner layer embedded with nano metal particles is about 4 GSM to 20 GSM.
In an embodiment, the nanometal particles are selected from the group comprising of silver, copper, zinc, gold and the like.
Further, in an embodiment, the second layer is selected from the group comprising of polyurethane and the aqueous solution for preparing the aqueous polyurethane is selected from the group comprising of water, anionic polyurethane binders, melamine cross linkers, curing agent, accelerator and the like.
In accordance to a preferred embodiment of the present invention, the water-resistant fabric has antimicrobial properties. It is to be noted that in view of absence of isocyanate, the fabric is an eco-friendly product. Further, there is no isocyanate fume formation due to aqueous coating and curing technology.
Figure 1 shows a water-resistant fabric comprising a base fabric (110) having a polyurethane coating on inner side (130), a second inner layer of polyurethane matrix (140) embedded with nano- silver particles (145) which gives anti-microbial property to fabric. The outer layer (120) is coated with fluorocarbon treated water repellent finish.
The water-resistant fabric of the present invention is not only water-resistant but also breathable and antimicrobial. The moisture vapor transmission rate (MVTR) of the fabric is 2000 g/m2 per day at 2000mm water column hydrostatic head. The same property achieved even after five wash cycle.
The embodiments of the invention shown and discussed herein are merely illustrative of modes of application of the present invention. Reference to details in this discussion is not intended to limit the scope of the claims to these details, or to the figures used to illustrate the invention.
It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention.

,CLAIMS:
1. A method for manufacturing of water-resistant fabric, said method comprising the steps of:
a) providing a base fabric (110) having an outer surface (120) and an inner surface (130),
b) coating the outer surface (120) of the base fabric (110) with a water-resistant coating (125),
c) coating the inner surface (130) of the base fabric (110) with multi-layered aqueous based coatings, wherein
the inner surface (130) of the base fabric (110) is coated with a first inner layer (135), wherein the first inner layer (135) is an aqueous polyurethane layer, and
the first inner layer (135) is coated with a second inner layer (140) that is embedded with nanometal particles (145) having an anti-microbial property, wherein the second inner layer (140) comprises an aqueous polyurethane matrix having nano-silver particles embedded thereon, and wherein the second inner layer (140) is in contact with the wearer’s skin.

2. The method as claimed in claim 1, wherein the base fabric (110) is a woven, non-woven, or knitted fabric.
3. The method as claimed in claim 1 or 2, wherein the base fabric (110) is made of natural or man-made fibres including polyester, nylon, p-aramid, m-aramid and combination thereof.

4. The method as claimed in claim 1, wherein the water-resistant coating (125) comprises a composition of about 4% to 20% of fluorocarbon water repellent and about 0.5% to 4% cross-linkers in water by weight of the coating composition.

5. The method as claimed in claim 1, wherein the GSM of the water- resistant coating is about 2 to 10 GSM.

6. The method as claimed in claim 1, wherein the GSM of the first inner layer (135) and the second inner (140) layer is 4 to 20 GSM.

7. The method as claimed in claim 1, wherein the second inner layer (140) comprises aqueous polyurethane in a range of about 80 to 95% (w/w), and further comprises thickening agents in a range of about 2 to 8% (w/w), curing agents in a range of about 1 to 8% (w/w) and antimicrobial agents in a range of about 0.5 to 10% (w/w) along with silica fumes in a range of about 1 to 6% (w/w) by weight of the second inner layer (140).

8. A water-resistant fabric, the fabric comprising:
a) a base fabric (110) having an inner surface and an outer surface,
b) a water-resistant coating (125) outside the outer surface,
c) a first inner layer (135) of coating on the inner surface of the base fabric, and
d) a second inner layer (140) embedded with nanometal particles over the first inner layer.

9. The water-resistant fabric as claimed in claim 8, wherein the base fabric (110) is a woven, non-woven, or knitted fabric made of natural or man-made fibres including polyester, nylon, p-aramid, m-aramid and combination thereof.

10. The water-resistant fabric as claimed in claim 8 or 9, wherein the water-resistant coating (125) comprises a composition of about 4% to 20% of fluorocarbon water repellent and about 0.5% to 4% cross-linkers in water by weight of the coating composition.

11. The water-resistant fabric as claimed in one of the preceding claims 8-10, wherein the second inner layer (140) comprises aqueous polyurethane in a range of about 80 to 95% (w/w), and further comprises thickening agents in a range of about 2 to 8% (w/w), curing agents in a range of about 1 to 8% (w/w) and antimicrobial agents in a range of about 0.5 to 10% (w/w) along with silica fumes in a range of about 1 to 6% (w/w) by weight of the second inner layer (140).

12. The water-resistant fabric as claimed in one of the preceding claims 8 - 11, wherein the GSM of the water- resistant coating is about 2 to 10 GSM and the GSM of the first inner layer (135) and the second inner (140) layer is 4 to 20 GSM.