ANTISLIP SHEET MATERIAL HAVING TAPES AND MONOFILAMENTS

Abstract

A sheet of material with an anti-skid surface, suitable for use as a roofing underlayment or wrapper, comprises a scrim made of woven plastic tapes with monofilaments that are round in cross-section and have a diameter larger than the thickness of the plastic tapes interwoven with the tapes. The monofilaments form ridges on the sheet material that impart an enhanced coefficient of friction to it. The monofilaments may be incorporated in the weave in the warp or weft directions or both.

Claims

1-19. (canceled)

20. A sheet of material having an anti-skid surface, comprising: a first set of tapes generally parallel to each other; a second set of tapes generally parallel to each other and perpendicular to the first set of tapes; the tapes being extruded plastic and having a width greater than their thickness; the tapes of the first set and of the second set being interwoven with each other to form a scrim; a first set of filaments generally parallel to the first set of tapes, each filament of the first set being positioned on a respective tape of the first set of tapes and following a weaving path the same as said respective tape of the first set of tapes, each said filament of the first set of filaments being interwoven with the tapes of the second set, the first set of filaments being exposed on only a first side of the sheet of material; the filaments of the first set of filaments being generally round in cross-section and having a diameter at least six times greater than the thickness of the respective first and second tapes and forming ridges on the first side of the sheet that provide the anti-skid surface.

21. The sheet of claim 20, further comprising a second set of filaments generally parallel to the second set of tapes, each filament of the second set being positioned on a respective tape of the second set of tapes and following a weaving path the same as said respective tape of the second set of tapes, each said filament of the second set of filaments being interwoven with the tapes of the first set of tapes and the filaments of the first set of filaments, the filaments of the first set of filaments and of the second set of filaments forming a grid on one side of the scrim; the filaments of the second set being round in cross-section and having a diameter greater than the thickness of the tapes and forming ridges on the surface of the sheet that further provide the anti-skid surface.

22. The sheet of claim 21, wherein the filaments of the second set of filaments have a diameter at least six times greater than the thickness of the tapes.

23. The sheet of claim 21, wherein the filaments of the second set of filaments are monofilaments.

24. The sheet of claim 23, wherein the tapes and monofilaments comprise polyolefin.

25. The sheet of claim 20, wherein the filaments of the first set of filaments are monofilaments.

26. The sheet of claim 25, wherein the tapes and monofilaments comprise polyolefin.

27. The sheet of claim 25, wherein the tapes and monofilaments comprise one or more of polyethylene, polypropylene, polyester, polystyrene, nylon or ethylene acrylic polymer.

28. The sheet of claim 20, wherein the filaments are one of cords, wires, string, ropes and burlap strings.

29. The sheet of claim 20, wherein the tapes of the first set are warp tapes.

30. The sheet of claim 20, wherein the tapes of the first set are weft tapes.

31. The sheet of claim 20, wherein a respective filament of the first set of filaments is positioned on every fourth tape of the first set of tapes.

32. The sheet of claim 20, wherein the filaments have a diameter at least twenty times greater than the thickness of the tapes.

33. The sheet of claim 20, wherein the thickness of the tapes is about 1 to 2 mils.

34. The sheet of claim 20, wherein the diameter of the filaments is about 10 to 30 mils.

35. The sheet of claim 20, wherein the tapes have a width in the range of 1.5 to 6 mm.

36. The sheet of claim 20, further comprising a coating layer bonded to the scrim.

37. The sheet of claim 36, wherein the coating comprises a tacky or high coefficient-of-friction material.

38. The sheet of claim 20, wherein the filaments comprise a tacky or high coefficient-of-friction material.

39. A sheet of material having an anti-skid surface, comprising: a first set of tapes generally parallel to each other; a second set of tapes generally parallel to each other and perpendicular to the first set of tapes; the tapes being extruded plastic and having a width greater than their thickness; the tapes of the first set and of the second set being interwoven with each other to form a scrim; a first set of filaments generally parallel to the first set of tapes, each filament of the first following a weaving path the same as said respective tape of the first set of tapes, each said filament of the first set of filaments being interwoven with the tapes of the second set; the filaments of the first set of filaments being generally round in cross-section and having a diameter at least six times greater than the thickness of the respective first and second tapes and forming ridges on a first side of the sheet that provide the anti-skid surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a plan view of a sheet according to one embodiment of the invention.

[0006] FIG. 2 is a plan view of a detail of the sheet.

[0007] FIG. 3 is a cross-sectional view on the line 3-3 of FIG. 2

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Exemplary embodiments are illustrated in the referenced figures of the drawings. It is intended that the embodiments are to be considered illustrative rather than restrictive.

[0009] The sheet material 30 has a scrim 32 coated on one side by a coating layer 34. The scrim 32 is woven in a plain weave of warp tapes 36 and weft tapes 38. Warp monofilaments 40 and weft monofilaments 42 are incorporated into the structure of the scrim 32. In particular, the warp monofilaments 40 are positioned on respective warp tapes 36 and are interwoven with the weft tapes 38; and the weft monofilaments 42 are positioned on respective weft tapes 38 and are interwoven with the warp tapes 36 and with the warp monofilaments 40. This produces a grid 44 of woven monofilaments on one side of the scrim 32. The appearance of, the sheet 30 is accordingly that of two overlapping woven scrims; one made of tapes and one of monofilaments. The warp and weft tapes 36, 38 provide the overall strength of the fabric and they hold the monofilament grid 44 in position.

[0010] In the illustrated embodiments, the warp and weft monofilaments are positioned every fourth warp or weft tape, respectively. Alternatively, they may be positioned on every second, or third, etc. tape, or at selected other spacings.

[0011] The thickness of the tapes 36, 38 is typically about 1-2 mils (0.025 to 0.05 mm). The thickness (i.e. diameter) of the monofilaments 40, 42 is about 10-30 mils (0.25 to 0.76 mm), for example about 15 mils. The monofilaments accordingly produce ridges on the surface of the scrim 32, running in both the warp and weft directions, which provide an increased coefficient of friction to the sheet 30.

[0012] To form an effective anti-skid surface, the height of the ridges should be at least about six times greater than the thickness of the tapes, alternatively at least about twenty times greater. For purposes of clarity of illustration, in FIGS. 2 and 3 the thickness of the tapes 36, 38 is exaggerated; it is to be understood that the monofilaments form ridges of substantial thickness, relative to the much smaller thickness of the tapes 36, 38.

[0013] The monofilaments are woven in such a way that the weft monofilaments 42 pass under the warp monofilaments 40, as best seen in FIG. 2. This results in the warp monofilaments 40 being raised at their points of intersection, increasing the height of the ridges at those points. The denier of the monofilaments and the spacing of the monofilaments in the weave can be varied to achieve the desired coefficient of friction.

[0014] The scrim 32, coating 34 and tapes 36, 38 are made of plastic, preferably polyolefin resins, for example polyethylene or polypropylene. They may alternatively be made of various other plastics, including polyesters, polystyrene, nylon and ethylene acrylic copolymers. The tapes 36, 38 and/or the coating 34 may alternatively comprise a high coefficient-of-friction material, for example ethylene vinyl acetate (EVA), ethylene methyl acrylate (EMA), rubber or elastomer. The monofilaments are generally round in diameter and can likewise be made of any suitable plastic, including the same plastics as the rest of the sheet.

[0015] The tapes 36, 38 are preferably about 1.5 to 6 mm in width. The number of tapes per inch in the machine direction and in the cross direction is preferably in the range of 1 to 25.

[0016] The coating layer 34 (shown in FIGS. 2 and 3) is a waterproof film bonded to the scrim. It may be permeable to water vapor to allow the escape of moisture from buildings when the sheet is used as a roofing underlayment or for similar applications. The coating layer 34 is manufactured in-situ using an extrusion process and is laminated to the scrim 32, or it can comprise a film that is bonded to the scrim, for example by thermal bonding, lamination or adhesive. Optionally, a second coating layer is bonded to the opposite side of the scrim.

[0017] In embodiments of the sheet materials of the invention, the sheet can be uncoated, coated on one side or on both sides, or it can include additional layers, or can include monofilaments in only the warp direction or only the weft direction or in both directions. The color of the monofilaments can be the same as the surrounding tapes to blend in or it can be pigmented to make the antislip grid visible. The monofilaments or the coating, or both, can be treated with or comprise a tacky or high coefficient-of-friction coating or additive, for example, EVA, EMA, rubber or elastomer. These choices depend on the properties desired for a particular application.

[0018] In other embodiments of the invention, filaments other than monofilaments 40 are used. Examples of suitable materials include cords, wire, string, rope and strings of burlap. For purposes of recyclability of the sheet material, it is desirable that the filaments and the tapes be of the same composition, or at least of plastics material that can be recycled together. Accordingly, plastic monofilaments are preferred to these alternative materials.

[0019] Although the invention has been described in terms of various embodiments, it is not intended that the invention be limited to these embodiments. Various modifications within the scope of the invention will be apparent to those skilled in the art. The scope of the invention is defined by the claims that follow.