Patent GB-984088-A (GB)
Title: Vapour permeable sheet materials
IPC: D06N3/14
Filed: 1962-10-24
Abstract: Microporous material in sheet form is produced by adding to a solution of a polymer in an organic solvent a non-solvent for the polymer which is at least partially miscible with the said solvent to cause a polymer-containing gel to separate, removing the gel from the residual liquid, applying the gel to a non-adhering support, e.g. of glass or metal, bathing the gel layer with a non-solvent for the polymer which is at least partly miscible with the solvent of the polymer solution used, drying the resulting microporous layer and stripping it from the support.  Specified polymers are polyurethane elastomers made by reacting a di-isocyanate with an active hydrogen-containing polymer, e.g. a polyalkylene ether glycol or a hydroxy-terminated polyester to produce an isocyanate-terminated prepolymer which is reacted with a chain-extending compound having two hydrogen atoms bonded to amino-nitrogen atoms, e.g. hydrazine, N-methyl-bis aminopropylene, dimethyl piperazine, and m-phenylene diamine; polyesters formed by reacting dicarboxylic acids, esters or acid halides with glycols, e.g. polymethylene glycols, substituted polymethylene glycols, cyclic glycols and aromatic glycols; carboxylic elastomers, i.e. interpolymers of carboxylic acid-containing monomers and C4- 10 conjugated dienes; terpolymers of an a ,b -unsaturated monocarboxylic acid, a C4- 6 conjugated diene and a vinyl compound, e.g. acrylonitrile, styrene or an acrylic or methacrylic ester; polyvinyl chloride and copolymers of vinyl chloride (preferably at least 80%) with vinyl acetate, vinylidene chloride and diethyl maleate; polyamides, polyesteramides, polyesters, polyvinyl butyral, poly-a -methyl styrene, alkyl acrylates and methacrylates, chlorosulphonated polyethylene, butadiene/acrylonitrile copolymers and cellulose esters and ethers. Specification 919,500 is referred to.ALSO:Vapour-permeable sheet materials are produced by (a) adding, to a solution of a polymer in an organic solvent, a non-solvent for the polymer which is at least partly miscible with the said solvent to cause a polymeric gel to separate; (b) removing the gel from the residual liquid; (c) applying the gel to a substrate; (d) bathing the gel layer with a non-solvent for the polymer; and (e) drying the resulting microporous layer. Specified polymers are polyurethane elastomers made by reacting a diisocyanate with an active hydrogen-containing polymer, e.g. a polyalkyleneether glycol or a hydroxy-terminated polyester, to produce an isocyanate-terminated prepolymer, which is reacted with a chain-extending compound having two active hydrogen atoms bonded to amino-nitrogen atoms, e.g. hydrazine, N-methyl-bis-aminopropylene, dimethyl piperazine, m-phenylene diamine or ethylene diamine; polyesters formed by reacting dicarboxylic acids, esters or acid halides with glycols, e.g. polymethylene glycols, substituted polymethylene glycols, cyclic and aromatic glycols; carboxylic elastomers, i.e. interpolymers of carboxylic-acid-containing monomers and C4-10 conjugated dienes; terpolymers of an a ,b -unsaturated monocarboxylic acid, a C4-6 conjugated diene and a vinyl compound, e.g. acrylonitrile, styrene or an acrylic or methacrylic ester; polyvinyl chloride and copolymers of vinyl chloride (preferably at least 80%) with vinyl acetate, vinylidene chloride and diethyl maleate; polyamides, polyesteramides, polyesters, polyvinyl butyral, polyalphamethyl styrene, alkyl acrylates and methacrylates, chlorosulphonated polyethylene, butadiene/acrylonitrile copolymers, cellulose ethers and esters. The substrate may be a flexible, porous fibrous material, e.g. a woven, knitted or non-woven fabric or a natural or synthetic leather or suede.  The examples refer to a substrate which is a non-woven polyethyleneterephthalate fibre sheet impregnated with a polyurethane elastomer.  The non-solvent used may be water or an organic liquid or mixtures thereof with the polymer solvent.  The gel may be coated on to non-adhering supports, e.g. of glass or metal, from which the film which is formed may be subsequently stripped (see Division C3).  Specification 919,500 is referred to.