Patent GB-1130576-A (GB)
Title: Sheet materials and production thereof
IPC: D04H1/64
Filed: 1965-10-15
Abstract: 1,130,576. Coated sheet material. E. I. DU PONT DE NEMOURS & CO. 15 Oct., 1965 [30 Oct., 1964], No. 43902/65. Heading B2E. [Also in Divisions C3, D1 and D2] A non-roughening sheet material comprises a non-woven fabric base treated with a synthetic organic polymer, said base comprising a coherent mass of enmeshed, entangled, helically micro-crimped fibres. The fibres have from 80 to 1000 crimps per inch of unextended length and crimp-elongation values greater than 10%. The base has a density of from 0.01 to 0.4 g/cm<SP>3</SP> and a tensile strength of from 0.05 to 4.0 pounds/inch/ounce/yd<SP>2</SP>, and the sheet material has a density of from 0.2 to 0.8g/cm<SP>3</SP>, an elongation at break of from 15% to 400% a polymer/fibre ratio of from 20/100 to 300/100, a Fisher pliability value of from 0 to 1200 and a Roughness Value (defined) of less than 4. The fibres may be already crimped before they are formed into the fabric base. Alternatively they may be capable of being crimped during the formation of the base, e.g. fibres composed of two different synthetic polymeric materials, or fibres of which one side has been drawn or cooled more than the other during manufacture. The fibres may be homofibres or bicomponent fibres of poly(ethylene terephthalate), poly (hexamethylene-adipamide), polyacrylonitrile, polypropylene, or copolymers of acrylonitrile and sodium styrene-sulphonate, ethylene terephthalate and ethylene isophthalate, hexaethylene adipamide and hexamethylene sebacamide, acrylonitrile and vinyl acetate or acrylonitrile and methyl methacrylate. Precrimped fibres can be formed into a web by carding, randowebbing or papermaking techniques and then pressed to entangle the fibres. Microcrimpable fibres can be formed into a loose batt by carding or rando-webbing and then held against shrinkage while subjected to an agency that will cause the micro-crimping. It may then be pressed. Alternatively. if some shrinkage is allowed' the product will be elastic. Crimping agencies referred to are: hot water, steam, mixtures of dimethylformamide and water as hot liquids or vapours, and mixtures of propylene carbonate or ethylene carbonate and water. In a third method of making the base fabric, continuous filaments are laid down by the electro-pneumatic spinning technique of specification 932,482, which are then pressed or calendered. The polymer may be applied by impregnating or coating, and may be polyvinyl chloride, polybutadiene, polyisoprene, a copolymer of vinyl chloride with vinyl acetate or vinylidene chloride, or of butadiene with acrylonitrile or styrene, or the polymer system of U.S. Patents 3,067,482 and 3,100,721. The fabrics may be first impregnated with a small amount of polymer, e.g. polyvinyl chloride, poly(methyl methacrylate), polybutadiene or polyisoprene, and then coated. In the Examples: (1) staple, bicomponet fibre of polyacrylonitrile and acrylonitrile/sodium styrenesulphonate copolymer is rando-webbed to form a batt, this batt is clamped between two frames and subjected to vapours of dimethylformamide and water to crimp the fibres, and then pressed between platens; polytetramethylene-ether glycol is mixed with tolylene-2, 4- diisocyanate and heated, then with methylenebis(4-phenyl isocyanate) and heated again; the polymer so formed is dissolved in dimethylformamide and added to a solution of N- methyl-amino-bispropyl-amine and hydrazine hydrate in dimethyl-formamide, this mixture is heated and then mixed with a solution of polyvinyl chloride in dimethylformamide, and a solution of water in dimethylformamide added until just before the solution becomes opalescent; the fabric above is floated on this dispersion and then pulled over a scraper knife to remove excess liquid, the dispersion in the fabric is coagulated by immersion in water, the material is soaked with water until free of solvent and dried; a polyurea-polyvinyl chloride-water-dimethylformamide solution prepared as above but in different proportions is knife-coated on to the fabric, coagulated in water, leached, dyed, dried, and finished with two coats of a tannery leather base finish and two of nitrocellulose lacquer and pressed against a smooth grained plate; (2) crimped, staple, bicomponent fibre of poly(ethylene isophthalate) and a poly(ethylene terephthalate) is carded into a web which is placed in water heated by steam under pressure to develop microcrimps and shrink the fabric; this fabric is split on a leather splitter and further processed as in Example 1; (3) staple fibres of poly(hexamethylene-adipamide), microcrimped by twisting and heat-setting, are carded into a batt and compressed, this batt is then further processed as in Example 1; (4) a base fabric is made and impregnated as in Example 1, and then given the coats of tannery leather base finish and nitrocellulose lacquer also as in Example 1 and embossed with a smooth grain plate; (5) a sheet is made as in Example 4 but for the tannery-finishing and embossing steps; coated with a solution of "Estane" in tetrahydrofuran, dried and embossed as in Example 4; (6) a base fabric is made as in Example 1, immersed in an acrylic latex, dried and coated as in Example 1; (7) continuous filaments of polypropylene, micro-crimped by knife-drawing are made into a web by the method of specification 932.482, which is further processed as in Example 1. The products resemble leather and can be used to make shoes or gloves.