Polymer-coated fabric

Abstract

Waterproof composite fabrics comprising a textile layer and a continuous polymer layer that comprises adjoining first and second regions with different physical or visual properties, and knife-over-roll coating methods for 5 manufacturing said composite fabrics. The waterproof composite fabrics described are particularly suitable for covering medical support surfaces, for instance mattresses.

Claims

1. A method of knife-over-roll coating for the manufacture of a waterproof composite fabric comprising a textile layer and a continuous polymer layer, said polymer layer comprising adjoining first and second regions that have different physical or visual properties, the first and second regions being in a side-by-side arrangement extending longitudinally along a length of the fabric, the first region being formed from a first polymer composition and the second region being formed from a second polymer composition, the method comprising simultaneously applying the first and second polymer compositions to the textile layer, and the textile layer and the applied first and second polymer compositions being moved by the rotation of a support roller beneath a knife, such that excess polymer composition is scraped off the textile layer by the knife, leaving a desired thickness of the adjoining first and second regions of the polymer layer, wherein one or more dividers are situated directly behind the knife, the one or more dividers subdividing the area immediately preceding the knife into a plurality of sub-sections, with at least one sub-section containing a first polymer composition and an adjacent sub-section containing a second polymer composition.

2. The method of claim 1, wherein the first and second polymer compositions each comprise one or more polymers and one or more solvents.

3. The method of claim 1, wherein the first and second polymer compositions are applied at a temperature between about 60-100° C.

4. The method of claim 1, further comprising a backplate located in the area preceding the knife, wherein the backplate, knife and support roller define three sides of a vessel, the vessel being divided by the dividers into the plurality of sub-sections of the area immediately preceding the knife.

5. A method of knife-over-roll coating for making a waterproof composite fabric comprising a textile layer and a continuous polymer layer, the polymer layer comprising adjoining first and second regions that have different physical or visual properties, the first and second regions being in a side-by-side arrangement extending longitudinally along a length of the fabric, the first region being formed from a first polymer composition and the second region being formed from a second polymer composition, the method comprising: a) simultaneously applying the first and second polymer compositions to a carrier, and the carrier and the applied first and second polymer compositions being moved by a support roller beneath a knife, such that excess polymer composition is scraped off the carrier by the knife, leaving a desired thickness of the adjoining first and second regions of the polymer layer, wherein one or more dividers are situated directly behind the knife, the one or more dividers subdividing the area immediately preceding the knife into a plurality of sub-sections, with at least one sub-section containing a first polymer composition and an adjacent sub-section containing a second polymer composition; b) applying a textile substrate to the surface of the polymer composition layer produced in step a), such that the polymer compositions bond to the textile; and c) removing the carrier.

6. The method of claim 5, wherein the first and second polymer compositions each comprise one or more polymers and one or more solvents.

7. The method of claim 5, wherein the first and second polymer compositions are applied at a temperature between about 60-100° C.

8. The method of claim 5, further comprising a backplate located in the area preceding the knife, wherein the backplate, knife and support roller define three sides of a vessel, the vessel being divided by the dividers into the plurality of sub-sections of the area immediately preceding the knife.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are illustrated by means of the following figures:

(2) FIG. 1 is a perspective view of a composite fabric according to the invention;

(3) FIG. 2 is a schematic diagram showing a cross-section of one embodiment of a composite fabric of FIG. 1 along the line X-X;

(4) FIG. 3 is a schematic diagram showing a cross-section of an alternative embodiment of a composite fabric of FIG. 1 along the line X-X;

(5) FIG. 4 shows a schematic diagram of the knife-over-roll coating method of the invention.

(6) FIG. 5 shows a perspective view of the schematic diagram of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows a composite fabric 10. The upper surface of the composite fabric 10 comprises three regions 11, 12, 13. Regions 11 and 13 are formed from the same polymer composition and therefore have the same physical and visual properties, while the intervening region 12 is formed from a second polymer composition and has different physical and/or visual properties.

(8) The composite fabric 10 is formed as a continuous piece of fabric, with the regions 11, 12, 13 extending longitudinally, and parallel, along the length of the fabric. Adjacent regions 11, 12 and 12, 13 are adjoining, such that the regions abut and are joined to each other, with no break or gap in the continuous polymer layer between them.

(9) FIG. 2 shows a schematic cross-sectional representation of an embodiment of the composite fabric depicted in FIG. 1. The composite fabric 20 shown in FIG. 2 comprises a textile layer 21, a polymer layer 27 and a layer of adhesive 26. The textile layer 21 forms the lower surface of the composite fabric 20, and is a knitted textile made from nylon. It will be appreciated that woven and non-woven textiles would also be suitable for use in the described composite fabric, made from nylon or other synthetic or natural fibres. The polymer layer 27 is formed of three regions 22, 23, 24. Regions 22 and 24 are formed from the same polyurethane polymer composition and therefore have the same physical and visual properties, while the intervening region 23 is formed from a second polyurethane polymer composition and has different physical and/or visual properties. The adjacent regions 22, 23 and 23, 24 are adjoining at 25. At the join 25 the polymer compositions, when forming the fabric, join to form a continuous polymer layer. At the join 25 there may be a clear distinction between the regions 22, 23 and 23, 24, such that there is no mixing of the polymer compositions. Alternatively, there may be a limited degree of merging of the polymer compositions at the join 25.

(10) Between the polymer layer 27 and textile layer 21 there is a layer of polyurethane adhesive 26, ensuring secure adhesion between the textile layer 21 and polymer layer 27.

(11) FIG. 3 shows a cross-sectional representation of an alternative embodiment of the composite fabric depicted in FIG. 1. The composite fabric 30 shown in FIG. 3 comprises a textile layer 31, an interlayer 36, a polymer layer 38 and a layer of adhesive 37. The textile layer 31 forms the lower surface of the composite fabric 30, and is a knitted textile. Directly above the textile layer 31 is a layer of polyurethane adhesive 37. On top of the layer of adhesive 37 is an interlayer 36 formed of polyurethane.

(12) Above the interlayer 36 and forming the upper surface of the composite fabric 30, the polymer layer 38 is formed of three regions 32, 33, 34. Regions 32 and 34 are formed from the same polyurethane polymer composition and therefore have the same physical and visual properties, while the intervening region 33 is formed from a second polyurethane polymer composition and has different physical and/or visual properties. The adjacent regions 32, 33 and 33, 34 meet at join 35. At the join 35 the polymer compositions, when forming the fabric, join to form a continuous polymer layer. At the join 35 there may be a clear distinction between the regions 32, 33 and 33, 34, such that there is no mixing of the polymer compositions. Alternatively, there may be a limited degree of merging of the polymer compositions at the join 35.

(13) FIGS. 4 and 5 show a schematic diagrams of the knife-over-roll coating method of the invention. A substrate 41 is moved in a continuous motion by the rotation of support roller 42 in the direction of arrow A. A knife 43 is suspended vertically above the support roller 42 with the gap between the knife blade 43 and the support roller 42 being proportional to the desired thickness of the coating on the substrate 41. A backplate 44 is located a distance behind the knife 43, and contacts the surface of the substrate 41. Dividers 45 separate the area defined by the backplate 44, knife 43 and support roller 42 into three sub-sections, each of which contain a polymer composition 46, 47, the polymer composition in the central sub-section being different to the polymer compositions in the adjacent sub-sections. The polymer composition 46, 47 contacts the area of the substrate above the support roller that is between the backplate and the knife. As the rotation of the support roller 42 moves the substrate 41, the un-coated surface of the substrate 41 comes into contact with the polymer composition 46, 47 in each sub-section simultaneously. Continuous rotation of the support roller 42 moves the substrate 41 under the knife 43, which only permits a thin layer of the polymer composition 46 contained in each sub-section to pass underneath, resulting in the substrate 41 being coated with polymer compositions 46, 47 in three regions 48, 49, the central region 49 differing from adjacent regions 48 in at least one physical or visual characteristic.