Patent GB-1000340-A (GB)
Title: Process for impregnating fibrous sheets
IPC: D04H1/06
Filed: 1963-07-01
Abstract: Solutions of polyurethane elastomers suitable for coating non-woven webs of fibres are produced by reacting polytetramethylene ether glycol having a molecular weight of about 1000 with tolylene-2,4-diisocyanate and reacting the hydroxyl terminated dimer with methylene-bis-(4-phenyl isocyanate) to produce a prepolymer having isocyanate groups which is dissolved in dimethyl formamide and reacted with a chain extender comprising N-methyl-bis-amino propylamine and hydrazine hydrate dissolved in dimethyl formamide to produce the polyurethane. Specification 905,824 is referred to.ALSO:Non-woven webs of heat-shrinkable fibres capable of shrinking 20-90% of their planar area and having a pattern on their surfaces are impregnated with an aqueous dispersion of a polymeric material, the impregnant coagulated and the impregnated webs then subjected to an elevated temperature to cause them to shrink 20-70% of their planar area.  100-400% by weight of the fibres of the dry impregnant which may be neoprene, butyl rubber, a copolymer of butadiene and acrylonitrile or styrene, natural rubber, plasticized polyvinyl chloride, an oil modified alkyd resin or an acrylic or methacrylic resin, may be applied, and coagulation may be effected by freeze coagulating, immersing the web in an aqueous solution of an electrolyte, heating the impregnated web, or allowing the impregnating composition to dry at room temperature.  The pattern may be applied to the webs by needle punching.  Shrinking may be effected by immersing the impregnated web in water at 63 DEG -93 DEG C.  Webs comprising polyethylene terephthalate, cellulose acetate, nylon, acrylonitrilevinyl chloride copolymer, polyethylene, polypropylene, polystyrene or polytetrafluoroethylene fibres alone or in admixture with cotton, jute, flax or wool may be treated.  The webs which may be used in the manufacture of shoe uppers, gaskets, diaphragms, bearing seals, fuel pumps, upholstery, pocket books, men's and ladies' jackets and paulins may subsequently be coated with a composition comprising a polyurethane elastomer and polyvinyl chloride dissolved in dimethyl formamide and dye.  Specification 905,824 is referred to.ALSO:Non-woven webs of heat-shrinkable fibres capable of shrinking 20-90% of their planar area and having a pattern on their surfaces are impregnated with an aqueous dispersion of a polymeric material, the impregnant coagulated and the impregnated webs subjected to an elevated temperature to cause them to shrink 20-70% of their planar area, and are then coated with a composition comprising a polyurethane elastomer and polyvinyl chloride dissolved in dimethyl formamide, immersed in water, steamed and dried. 100-400% by weight of the fibres of the dry impregnant which may be neoprene, butyl rubber, a copolymer of butadiene and acrylonitrile or styrene, natural rubber, plasticized polyvinyl chloride, an oil modified alkyd resin or an acrylic or methacrylic resin, may be applied, and coagulation may be effected by freeze coagulating, immersing the web in an aqueous solution of an electrolyte, heating the impregnated web, or allowing the impregnating composition to dry at room temperature.  The pattern may be applied to the webs by needle punching.  Webs comprising polyethylene terephthalate, cellulose acetate, nylon, acrylonitrilevinyl chloride copolymer, polyethylene, polypropylene, polystyrene or polytetrafluoroethylene fibres alone or in admixture with cotton, jute, flax or wool may be treated.  When the web coated with the composition comprising a polyurethane elastomer and polyvinyl chloride dissolved in dimethyl formamide is immersed in water the coating solution is coagulated and converted into a gelatinous polymeric layer having a cellular structure of interconnecting micropores and substantially all of the dimethyl formamide is extracted from the solution coating.  After steaming and drying the coating obtained is highly permeable to water vapour.  The coated web may be dyed and scoured and used in the production of shoe uppers.  Specification 905,824 is referred to.