Patent GB-1094064-A (GB)
Title: Substitutes for leather and method of manufacturing the same
IPC: D04H1/64
Filed: 1964-11-16
Abstract: A substitute for leather comprises (1) a nonwoven fibrous mat predominantly comprising the fibre prepared by extracting at least one polymer from a fibre of a blended polymeric composition by the use of a solvent therefor which is not a solvent for at least one other polymer in the fibre, and (2) a separate interpenetrating body comprising at least one polymeric material.  It may be made by forming a web or mat of fibre of a blended polymeric composition, impregnating with a solution or emulsion of one or more polymeric materials, coagulating the impregnant and extracting at least one of the polymers in the fibre by the use of a solvent therefor which is not a solvent for at least one other polymer in the fibre.  The fibres may be obtained by the mixed spinning, e.g. wet-spinning, dry-spinning or melt-spinning, or two or more polymers and subsequently stretched.  They may be crimped and of staple length, and may be formed into a web or mat by random webbing and needle-punching or by wet methods.  In the examples fibres are of nylon -6 and polystyrene, polyethylene terephthalate and polystyrene, polyacrylonitrile and polyvinyl alcohol, or nylon-6 and polyvinyl alcohol, polystyrene being extracted with toluene or cyclohexane, or polyvinyl alcohol with water.  Other fibre-forming polymers referred to are: polyolefins; alkyl- and halogen-substituted polystyrenes, atactic and isotactic polystyrenes; polymethacrylates; polyvinyl esters, alcohols and halides; polyacrylonitrile; and polyvinylidene halides; The mat or web may also contain homopolymer fibres or natural fibres. Other solvents referred to are cyclic ethers, diphatic hydrocarbons, diphatic and cyclic ketones, methanol solutions of calcium chloride, titanium tetrachloride or lithium chloride, and mixtures of these.  The fibre mat may be compressed with or without heat, and the fibres in it may be shrunk while the mat itself is held to constant dimensions.  The binder may be one or more elastomers, e.g. segmented polyurethane, polyacrylates, synthetic rubber or chlorinated polyethylene, or a mixture of one or more of these with one or more non-rubbery polymers, e.g. polyvinyl chloride, polyacrylonitrile, polystyrene; polyvinyl alcohol, acetal or acetate; polyamides; polypropylene, polyethylene, non-elastomeric polyurethane, polyurea, polyester or polycarbonate.  The impregnant solution or emulsion may also contain salts, dyes, pigments, fillers or surface-active agents. The impregnant may be coagulated by a dry or wet process, and the web may be pressed before, during or after coagulation.  The coagulation of the binder and extraction of fibre may be simultaneous.  The product may be coated before or after the extraction to provide a surface simulating natural leather.  This coating may be of the same polymer as the binder.  The impregnant or the coating or both may themselves be partially extracted by the solvent in the extracting step.  The back surface of the product may be buffed.ALSO:A substitute for leather is made by coating a sheet that comprises (1) a non-woven fibrous mat predominantly comprising the fibre prepared by extracting at least one polymer from a fibre of a blended polymeric composition by the use of a solvent therefor which is not a solvent for at least one other polymer in the fibre, and (2) a separate interpenetrating body comprising at least one polymeric material.  It may be made by forming a web or mat of fibre of a blended polymeric composition, impregnating with a solution or emulsion of one or more polymeric materials, coagulating the impregnant and extracting at least one of the polymers in the fibre by the use of a solvent therefor which is not a solvent for at least one other polymer in the fibre.  The fibres may be obtained by the mixed spinning, e.g. wet-spinning, dry-spinning or melt-spinning, of two or more polymers and subsequently stretched.  They may be crimped and of staple length. In the examples fibres are of nylon -6 and polystyrene, polyethylene terephthalate and polystyrene, polyacrylonitrile and polyvinyl alcohol, or nylon-6 and polyvinyl alcohol, polystyrene being extracted with toluene or cyclohexane, or polyvinyl alcohol with water.  Other fibre-forming polymers referred to are: polyolefins; alkyl- and halogen-substituted polystyrenes; atactic and isotactic polystyrenes; polymethacrylates; polyvinyl esters, alcohols and halides; polyacrylonitrile; and polyvinylidene halides.  The mat or web may also contain homopolymer fibres or natural fibres.  Other solvents referred to are cyclic ethers, aliphatic hydrocarbons, aliphatic and cyclic ketones, methanol solutions of calcium chloride, titanium tetrachloride or lithium chloride, and mixtures of these.  The binder may be one or more elastomers, e.g. segmented polyurethane, polyacrylates, synthetic rubber or chlorinated polyethylene, or a mixture of one or more of these with one or more non-rubbery polymers, e.g. polyvinyl chloride, polyacrylonitrile, polystyrene; polyvinyl alcohol, acetal or acetate; polyamides; polypropylene, polyethylene, non-elastomeric polyurethane, polyurea, polyester or polycarbonate.  The impregnant solution or emulsion may also contain salts, dyes, pigments, fillers or surface-active agents. The product may be coated before or after the extraction to provide a surface simulating natural leather.  This coating may be of the same polymer as the binder.  The impregnant or the coating or both may themselves be partially extracted by the solvent in the extracting step.  The back surface of the product may be buffed.