HK1001898B - Method of forming a drapable, water-vapor permeable, wind and water resistant composite fabric - Google Patents

Description

The invention relates to a method of forming a drapable, water-vapor permeable, wind and water resistant composite fabric and to the composite fabric obtained thereby.

It is known from U.S. Patent No. 4,056,646 to deposit a layer of foamed adhesive, namely foamed latex, on a major surface of a fabric substrate, namely a fibrous sheet, and to adhere a flock fiber layer suitable for exposed use to said adhesive layer interlocking with the adhesive layer to define a surface of the composite fabric.

It is known to adhere a rubber layer to a fabric sub-strate to impart waterproof qualities and the exposed surface of the rubber layer was flocked. Foamed adhesives have been used to adhere layers of flock in upholstery fabrics. These fabrics, however, have generally been formed using an open weave Osnaburg fabric as a fabric substrate and do not have the degree of drapeability required for apparal fabrics.

JP-A-62-199882 describes a method for producing fine-fibre flocked products. After water repellency treatment a resin emulsion type adhesive agent was applied to the substrate surface. Flocking of fibre was conducted to produce a pile which was subject to a fine fibre forming treatment. In this citation, however, there is no indication as to the use of a foamed adhesive or the amount thereof.

US-A-4,308,303 and US-A-4,353,945 teach flocked, foam coated, fibrous reinforced, water-vapor permeable bacterial barriers for forming surgical drapes and gowns and similar articles. The barriers include a microporous polyolefin film coated with a foamed latex polymer upon which a layer of fibers is flocked.

The barriers, however, are not suitable for apparel use since the flock is adhered to a polyolefin film, not a fabric.

The object of the invention is to provide an improved composite fabric which eliminates these problems associated with prior art fabrics and provides a novel, inexpensive, soft, drapable, water-vapor permeable, wind and water resistant composite fabric and to provide a single fabric which performs functions of multiple layers of fabric.

For the accomplishment of this object, the method is characterized by the steps of

• applying an adhesive barrier layer (13) of a water repellant material to a fabric substrate (11) on a major surface (22) of said fabric substrate (11); wherein the weight of the fabric substrate with the adhesive barrier layer (13) is 0.5 to 1.3% greater than the weight of the fabric substrate (11) alone;
• depositing a thin foamed adhesive layer (15) on said adhesive barrier layer (13) via said major surface (22) interlocking with said major surface (22) on said adhesive barrier layer (13), said foamed adhesive layer (15) having pores large enough to allow water-vapor to pass therethrough but too small to allow air or liquid water to pass therethrough, wherein the density of the adhesive is reduced between 10 and 75 percent by foaming; said foamed adhesive layer (15) being substantially prevented from penetrating into the fabric substrate (11) below said adhesive barrier layer (13) by said adhesive barrier layer (13);
• adhering a flock fiber layer (17) suitable for exposed use to said foamed adhesive layer (15) interlocking with said foamed adhesive layer (15) to define a surface of the composite fabric;
• wherein said adhesive barrier layer (13) comprises a material which lowers the surface tension of said substrate (11) below the surface tension of said foamed adhesive layer (15).

The adhesive remains substantially in the surface region of the fabric substrate by reason of the layer of adhesive barrier material applied to the fabric substrate before the adhesive is applied. An incomplete portion of the adhesive barrier material layer may remain in the composite fabric after finishing. The pores of the foamed adhesive are large enough to allow water- vapor molecules to pass through, however, the pores are too small to allow air or liquid water molecules to pass through except under pressure, rendering the fabric wind and water resistant.

The fabric substrate is preferably a fabric suitabe for aparel use and preferably a fabric raised on one side, the foamed adhesive being applied to the other (unraised) side of the fabric. The adhesive layer is sufficiently thin and selected to provide drapeability of the finished fabric.

The composite fabric according to the invention is manufactured by applying an adhesive barrier material to the fabric substrate and depositing a layer of foamed adhesive on the adhesive barrier material. A layer of flock fibers is deposited on the adhesive. The adhesive barrier material may be a material which reduces the surface tension of the fabric substrate to a level below that of the adhesive such as a water repellent material. The adhesive barrier material may be substantially removed during later processing of the composite fabric.

Accordingly, it is an object of the invention to provide an improved composite fabric.

A further object of the invention is to provide an improved composite fabric which is water resistant.

A still further object of the invention is to provide a fabric which is liquid water resistant and water vapor permeable.

Another object of the invention is to provide a water resistant composite fabric having drapeability suitable for apparel.

Yet another object of the invention is to provide a composite fabric which is insulative.

Still another object of the invention is to provide a water resistant fabric which is crack resistant at low temperatures.

Yet still another object is to provide a composite fabric which is wind resistant.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification and drawings.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWING

For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:

The figure is an enlarged sectional schematic view of a composite fabric in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMDODIMENTS

Reference is made to the figure wherein a composite fabric, generally indicated at 10, is schematically depicted. Composite fabric 10 includes a fabric substrate 11, and an incomplete layer of an adhesive barrier material 13 deposited on fabric substrate 11. A thin layer of foamed adhesive 15 is deposited in and interlocked with the surface region of the fabric substrate. The remaining portions of a layer of adhesive barrier material 13 is positioned immediately below the adhesive layer which maintains the adhesive in the surface region of the fabric. A layer of flock fibers 17 is deposited on adhesive 15.

Fabric substrate 11 is a knit fabric suitable for exposed use. Preferably, fabric substrate 11 is suitable for apparel. Any plain or textured fabric can be used provided the fabric meets the drapeability standard of the consumer. Fabric substrate 11 is formed of a natural or synthetic fiber or blend thereof including polyester, acrylic, wool, cotton, nylon, etc. In a preferred embodiment, fabric substrate 11 has a raised surface with the flat technical face or jersey surface 22 of the fabric substrate being flocked and the raised surface 23 being exposed. Such a raised surface fabric provides a garment particularly suited for outerwear because of the warmth of the fabric and the "soft" raised surface against the body. Preferred raised surface fabrics include a terry loop, three-end fleece or two-end fleece construction.

In one embodiment, fabric substrate 11 is a knit fabric, preferably a circular weft knit fabric, e.g. a circular weft knit polyester terry loop fabric. The loop yarn may be filament or spun. If the loop yarn is filament, it is between about 70 and 150 denier, preferably 100 denier. If the loop yarn is spun it is between about 24 and 18 singles. The stitch yarn is filament between about 70 and 150 denier, preferably 100 denier. The fabric is between about 0.076 and 0.76 cm (0.030 and 0.30 inches) thick, preferably 0.18 cm (0.070 inches) thick. However, this fabric substrate is described by way of example but not by way of limitation. Fabric substrate 11 may be dyed conventionally with, for example, disperse dyes.

An adhesive barrier material 13 is applied to fabric substrate 11. The purpose of the adhesive barrier material is to keep the adhesive material substantially in the surface region of the fabric substrate so that a thin, porous (to the extent required for water vapor permeability (breathability)) and flexible (drapable) layer of adhesive is produced without affecting the adherence of the adhesive. A material which reduces the surface tension of the fabric substrate to a level below that of the adhesive may serve as an adhesive barrier material. A water repellent material performs such a function and may be used with water based adhesives. An aluminum wax is one material suitable for this purpose because it does not itself adversely affect the drapeability characteristic of the final fabric or interfere with the operation of the adhesive, much of the aluminum wax being removed in later processing. The thin surface layer of adhesive performs the desired flock bonding function without rendering the fabric too stiff to serve as an apparel material.

Adhesive barrier material 13 is a water repellent material, and may be an aluminum wax, which may be applied by conventional padding methods during which fabric substrate 11 is dipped in a water based solution which includes the adhesive barrier material. The excess solution is squeezed out when substrate 11 is passed through heavy rollers. The weight of fabric substrate 11 with the adhesive barrier material may be between about 0.5% and 1.3% greater than fabric substrate 11 alone, preferably about 0.9% greater. Preferably, adhesive barrier material 13 is an aluminum wax such as Aridry AA, manufactured by C.N.C. Chemical Co.

Fabric substrate 11, after application of the adhesive barrier material, is dried utilizing conventional drying techniques. Side 23 of fabric substrate 11 is raised by conventional techniques such as by napping and fabric substrate 11 is heat-set.

Adhesive 15 is applied to an unraised side 22 of substrate fabric 11 with a doctor blade or by another application process. Adhesive 15 is a water resistant foamed adhesive, and may be formed from an acrylic latex or acrylic polyurethane, to which may be added an acrylic thickener and ammonia. One example of an adhesive is HYCAR® 26387 adhesive of The BF Goodrich Company, an acrylic latex. Approximately 1% by weight of an acrylic thickener may be added to the acrylic latex or acrylic polyurethane. The acrylic thickener improves the viscosity of the adhesive under shear. After the thickener is added, approximately 1% by weight of ammonia may be added until the pH of the mixture is approximately 8.5 to control the adhesive viscosity.

The adhesive may be foamed by aeration, for example, by using an Oakes foamer. Any other suitable foaming method, including chemical foaming, may be used. The density of the adhesive is reduced between about 10 and 75 percent, preferably, between about 25 and 50 percent. Foaming increases the porosity and renders the adhesive water vapor permeable, allowing finished fabric 10 to be breathable. The size of the pores in the foam must be large enough to allow water vapor to pass through but small enough to limit liquid water and air from passing through.

In one example, at 50% foam density, a satisfactory water vapor transfer rate of 624 g/m²/24 hrs was obtained using Procedure B (65% humidity) of ASTM E-96. Liquid water transfer occurred at a hydrostatic pressure of 15.1 cm using Method B (Suter) of ASTM D-751 (a measure of relative water resistance). Air flow through the fabric (a measure of relative wind resistance) measured 7.7 m³/ minute/m² (25.3 ft³/minute/ft²). In another example, at 75% foam density, a satisfactory water vapor transfer rate of 344 g/m²/24 hrs was obtained using Procedure B (65% humidity) of ASTM E-96. Liquid water transfer occurred at a hydrostatic pressure of 25.7 cm using Method B (Suter) of ASTM D-751 (a measure of relative water resistace). Air flow through the fabric (a measure of relative wind resistance) measured 0.78 m³/minute/m² (2.56 ft³/minute/ft²). Accordingly, when the foam density is 75%, an extraordinarily wind resistant fabric is produced. A wind resistance, as measured above, of less than about 1.1 m³/minute/m² (3.5 ft³/minute/ft²) would be considered highly desirable and achievable by selection of foam density.

When foam density is decreased, and therefore foam porosity increases, the moisture vapor transfer rate increases but the water resistance declines as does the wind resistance. On the other hand, increasing foam density, and therefore decreasing foam porosity, decreases moisture vapor transfer rate, increases water resistance and increases the wind resistance.

When a fabric is used for outerwear, each of these three characteristics plays a role. It is desired to provide a breathable fabric which enables water vapor to pass through the fabric to prevent the trapping of body moisture. The result is greater comfort. It is desired to provide water resistance so that the garment can be used in rainy weather or in snow. The desired goal is to maximize this characteristic without undue sacrifice of the breathability characteristic. It is desired to provide wind resistance so that the garment can be used in windy weather.

The thickness of adhesive 15 is between about 0.35 and 0.65 mm, preferably, the thickness is about 0.50 mm. If the layer of adhesive is too thin, adhesive 15 will not hold the flock fibers and will not form a barrier which is relatively impenetrable by air and liquid water. If adhesive 15 is too thick, composite fabric 10 will lose its breathability and drapeability.

In a preferred embodiment flock fibers 17 are applied to substrate 11 by conventional flocking methods, including electrostatic flocking and mechanical flocking methods. Preferably, flock fibers 17 are attached using an electrostatic flocking method. Flock fibers 17 are formed of nylon, cotton, rayon, acrylic, polyester, wool, a combination of the above or the like. Preferably, flock fibers 17 are 100% nylon. When nylon fibers are used, the fibers may be semi-dull, bright or dull, preferably, the fibers are dull Nylon 6.6. The length of flock fibers 17 is between about 0.5 and 3.0 mm, preferably, 2.1 mm. The size of flock fibers 17 is between about 0.8 and 6.0 denier, preferably about 3.0 denier.

By printing on the composite fabric or on the fabric substrate and using an essentially transparent adhesive and by various flock on flock techniques, as more particularly taught in U.S. patent application No. 07/422,850, filed October 17, 1989, assigned to the assignee hereof, various decorative effects can be created. However, the use of unflocked regions as taught in some embodiments of the application, would not provide the desired wind and water resistant fabric. The disclosure of U.S. application Serial No. 07/422,850 is incorporated herein as if fully set forth herein.

Composite fabric 10 undergoes a conventional drying and curing process to dry and cure adhesive 15 and strengthen the chemical bonds which hold flock fibers 17 to fabric substrate 11. Following the drying and curing process, composite fabric 10 is conventionally washed in a jet washing machine with soap and detergents to remove chemicals and loose fibers remaining from the flocking process. A conventional finishing agent may be applied at this time. During the washing process, all or substantially all of the adhesive barrier layer is scoured off the raised surface of the composite fabric.

Composite fabric 10 is conventionally dried. Preferably, drying is accomplished in a tensionless dryer. Composite fabric 10 is refinished to unmat the raised (unflocked) side of the fabric. Finally, composite fabric 10 is tentered to pull it out to width.

The resultant fabric has good drapeability, feel and appearance characteristics making it particularly suited for garments. Further, the fabric provides good breathability (moisture vapor permeability) while providing a satisfactory level of wind and water resistance for the intended applications.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the article set forth without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Claims (35)

1. A method of forming a drapable, water-vapor permeable, wind and water resistant composite fabric, comprising the steps of:

   - applying an adhesive barrier layer (13) of a water repellant material to a fabric substrate (11) on a major surface (22) of said fabric substrate (11); wherein the weight of the fabric substrate with the adhesive barrier layer (13) is 0.5 to 1.3% greater than the weight of the fabric substrate (11) alone;

   - depositing a thin foamed adhesive layer (15) on said adhesive barrier layer (13) via said major surface (22) interlocking with said major surface (22) on said adhesive barrier layer (13), said foamed adhesive layer (15) having pores large enough to allow water-vapor to pass therethrough but too small to allow air or liquid water to pass therethrough, wherein the density of the adhesive is reduced between 10 and 75 percent by foaming; said foamed adhesive layer (15) being substantially prevented from penetrating into the fabric substrate (11) below said adhesive barrier layer (13) by said adhesive barrier layer (13);

   - adhering a flock fiber layer (17) suitable for exposed use to said foamed adhesive layer (15) interlocking with said foamed adhesive layer (15) to define a surface of the composite fabric;

   - wherein said adhesive barrier layer (13) comprises a material which lowers the surface tension of said substrate (11) below the surface tension of said foamed adhesive layer (15).
2. The method of claim 1, wherein the adhesive barrier layer (13) is water repellent.
3. The method of claim 1, wherein the adhesive barrier material is an aluminum wax.
4. The method of claim 3, wherein the aluminum wax is applied by padding.
5. The method of claim 4, wherein the fabric substrate is dried before application of the adhesive.
6. The method of claim 5, wherein the fabric substrate is heat set prior to application of the adhesive.
7. The method of claim 1, further including the step of raising the fabric substrate on the surface which is opposed to the major surface.
8. The method of claim 1, further including the step of dyeing the fabric substrate prior to applying the adhesive barrier material.
9. The method of claim 1, further including the step of printing the composite fabric.
10. The method of claim 1, further including the steps of washing and drying the composite fabric.
11. The method of claim 10, wherein the washing step removes a substantial portion of the adhesive barrier material.
12. The method of claim 10, further including the step of finishing the washed and dried composite fabric.
13. The method of claim 1, wherein the fabric substrate is suitable for apparel.
14. The method of claim 1, wherein the material and thickness of the adhesive layer are selected to be sufficiently flexible to enhance the drapability of the fabric.
15. The method of claim 1, wherein the fabric substrate is polyester.
16. The method of claim 1, wherein the fabric substrate is a raised fabric, raised on one side only, the adhesive being on the surface region of the other, unraised side of the fabric substrate.
17. The method of claim 1, wherein the fabric substrate is a knit fabric.
18. The method of claim 1, wherein the fabric substrate has a terry loop construction.
19. The method of claim 1, wherein the fabric substrate has a three-end fleece construction.
20. The method of claim 1, wherein the fabric substrate has a two-end fleece construction.
21. The method of claim 1, wherein the fabric substrate is a circular weft knit fabric.
22. The method of claim 1, wherein the fabric substrate is between about 0.076 and 0.76 cm (0.03 and 0.30 inches) thick.
23. The method of claim 22, wherein the fabric substrate is about 0.18 cm (0.07 inches) thick.
24. The method of claim 1, wherein the adhesive includes an acrylic latex.
25. The method of claim 1, wherein the adhesive includes an acrylic polyurethane.
26. The method of claim 1, wherein the density of the adhesive is reduced by foaming the adhesive.
27. The method of claim 1, wherein the density of the adhesive is reduced about 50 percent.
28. The method of claim 1, wherein the density of the adhesive is reduced about 25 percent.
29. The method of claim 1, wherein the density of foam is selected to provide a wind resistant fabric having an air flow less than about 1.1 m³/minute/m² (3.5 ft³/minute/ft²).
30. The method of claim 26, wherein the foaming of the adhesive is by aeration.
31. The method of claim 1, wherein the adhesive layer is between about 0.35 and 0.65 mm thick.
32. The method of claim 26, wherein the adhesive layer is about 0.50 mm thick.
33. The method of claim 1, further including the step of dyeing the composite fabric.
34. The method of claim 13, further including the step of applying water repellant to the washed composite fabric.
35. A drapable, water vapor permeable, wind and water resistant composite fabric produced according to one of the methods set forth in any of claims 1 to 34.