Patent GB-1321852-A (GB)
Title: Fibrous sheet and a method of manufacturing the same
IPC: D04H1/48
Filed: 1970-06-25
Abstract: 1321852 Laminated fibrous layers TORAY INDUSTRIES Inc 25 June 1970 [1 July 1969 (3)] 30842/70 Heading B5N [Also in Division D1] A fibrous sheet comprises a first fibrous layer 38 wherein the majority of the component fibres run substantially in the thickness direction and a second fibrous layer 28, 29 wherein the majority of the component fibres run substantially in the surface direction, the two layers being united on a superimposed disposition, component fibres of one layer penetrating into and being entangled with the component fibres of the other layer in the boundary area of the layers and the outer surface of the first layer being uniformly covered with naps formed from its component fibres. The sheet may be made by preparing a first fibrous layer 38 wherein the majority of component fibres run substantially in the thickness direction and tow second fibrous layers 28, 29 wherein the majority of component fibres run substantially in the surface direction, sandwiching the first layer between the second layers, uniting the assembled layers into a web by needle punching, slicing the first fibrous layer in the surface direction so as to form two separate sheets and napping the sliced surfaces of the individual sheets. The first fibrous layer is preferably made by slitting a fibrous web, the majority of the component fibres of which run substantially in the surface direction, the slitting being effected at intervals of from 1 to 20 mm. in the surface direction and assembling the slit portions of web in a side-by-side arrangement with their slit surfaces exposed. In the embudiment of Fig. 3, the first fibrous layer 38 is formed by cutting a fibrous web 21 through its thickness into pieces 24, turning the pieces through 90 degrees as shown by the arrows 34 and advancing the resultant pieces 27 to form the layer 38. In the embodiment of Fig. 4, the first fibrous layer 38 is formed by feeding the web 21 into a conduit 44, the web being cut into pieces by a vertically reciprocating cutting blade 43, the pieces falling down the vertical limb of the conduit and changed in direction by 90 degrees as they pass into the horizontal limb of the conduit. In the embodiment of Figs. 5 and 6, the first fibrous layer is formed by passing the web 61 to a pair of slitting rollers 64 which slit the web into a plurality of side-by-side webs 66 which are turned through 90 degrees in guide path tubes 72 of direction converter 69. The fibrous layers may be produced on a random webber or a cross-lapper. The first fibrous layer may be compacted, e.g. by pressing before cutting. One of the second layers may be subjected to a preliminary needle punching operation prior to assembly of the layers. The needle punching of the assembled layers may be effected by a multistage process and may be effected at a slight inclination to the vertical. The fibres of the layers may be synthetic, e.g. of polyamide, polyester, acrylic, polyurethane, polyolefine, polyvinyl, fluorine polymer or silicone, natural fibres, e.g. of wool, cotton, jute or hemp, blended fibres, block-copolymer fibres, composite fibres, fibres of irregular cross-section and fibres composed of at least two different types of high polymeric components one of which is called the island component, e.g. a polyamide, a polyester, a polyolefin, a polyacrylonitrile or a polyurethane and comprisse strands embedded in a matrix provided by a "sea-component", e.g. polystyrene, polyvinyl alcohol, polyethylene oxide, polyethylene glycol or polymethyl methacrylate, the island components being distributed in and isolated from each by the sea component. In one embodiment, when said " islands-in-a-sea " type fibres are used, the needled assembly of webs is impregnated with a water soluble polymer and the resultant product treated with a solvent to remove the sea component prior to impregnation of the needled assembly with an elastic polymeric substance and removal of the water-soluble polymeric material. Specified elastic polymeric materials are solutions, emulsions or dispersions of a polyurethane, a polyurea, polyvinyl chloride, natural rubber, acrylonitrile-butadiene rubber and acrylonitrile rubber. The products of the invention may be used as substitutes for leather or velveteen, as felts in the paper making industry, as fabrics for interior decoration, as pads or mats, as thermal insulation, as sacks, as cushions and in clothing.