GB1155531A - Permeable Materials - Google Patents

Abstract

1,155,531. Porous coating. CARL FREUDENBERG K.G. 12 April, 1966 [8 April, 1965], No. 16068/66. Heading B2E. [Also in Divisions B5 and C3] Films of elastomeric polymers permeable to air and water vapour are made by spraying a solution of the polymer towards a surface and spraying separately and at the same time an excess of a coagulant miscible with the solution so that coagulation of the polymer and hardening of the resultant bodies proceed but are not completed before the polymer reaches the surface. Some but not all of the coagulant required to coagulate the polymer is mixed into the polymer solution and the remainder of coagulant used is sprayed separately towards the surface. Suitable polymers include chlorosulphonated polyethylenes, polydienes such as polyisoprene, diene copolymers such as copolymers of butadiene with acrylonitrile, acrylic and methacrylic acid esters, styrene and vinylidene chloride and also their terpolymers with an acrylic or methacrylic acid ester of a basic monomer such as N,N-dimethylaminoethyl acrylate, acrylamide or methacrylamide, N-methylolacrylic or methacrylic amide, or an epoxidecontaining monomer, polymers of 2-chlorobutadiene and polymers, copolymers of esters of acrylic, methacrylic acid with alcohols having 1 to 18 carbon atoms, and copolymers of these with one another and with styrene, acrylonitrile, vinylidene chloride, optionally with cross-linking agents such as metallic oxides, condensation products of formaldehyde, and acid donors. Polymers or copolymers or vinyl ether such as ethylvinyl or isobutyl vinyl ether, uncross-linked or slightly. cross-linked polyurethanes, and prepolymers e.g. polyurethane prepolymers may be used. The above polymers may be mixed with one another or with harder polymers such as polyvinyl chloride, polystyrene e.g. mixtures of butadiene-acrylonitrile-methacrylic acid copolymer or chlorosulphonated polyethylene or polyester urethane with polyvinyl chloride. Suitable solvent-polymer-coagulant systems are disclosed. For the majority of polymers, hydrophilic coagulants such as water, alcohols and mixtures thereof are preferred, although other coagulants such as hydrocarbons, ethers, alcohol-ether mixtures may be desirable e.g. when polyurethane prepolymers having free isocyanate groups that react with water are used. Various additives may be sprayed with the polymer e.g. pigments, organic dyestuffs, wetting agents, fillers, water-proofing agents such as silicones, greases, paraffin, plasticizers. Fibres or woven fabric or non-woven fleece may be worked into the coating. Microporous coatings on a knitted, woven or needled non- fabric to produce a leather substitute may be formed. The non-woven fabric may have been impregnated with a binder. The fabric may be sprayed initially with a solution of a polymer in the absence of sufficient coagulant for coagulation. The abrasion resistance of the coating may be improved and undesired permeability reduced by applying a suitable finish e.g. one based on polymethacrylate, polyurethane, polyamide applied say by spraying or roller lacquering mill. In the Examples, (1) a polyurethane is coagulated on to a needled polyamide fleece impregnated with polyurethane and a glazing lacquer with a polyamide, polymethyl methacrylate polymer or copolymer, or polyurethane base applied by spraying; (2) a polyurethane-polyvinyl chloride mixture pigmented with carbon black is coagulated on to polyurethane impregnated polyamide fleece, and a pigmented finish of a polyurethane ketone applied; (3) a pigmented mixture of polyurethane and polyvinyl chloride is coagulated on to a needled, polyurethane-impregnated polyamide fleece and finished as in (2); (4) a polyurethane adduct is coagulated on to the smooth side of a cotton twill roughened on one side and impregnated with an emulsion of butadiene-acrylonitrile-methacrylic and terpolymer latex; and the polyurethane cross-linked; (5) an acrylic and ethyl ester-acrylohitrile-methacrylic acid copolymer is coagulated on to a polyamide fleece impregnated with a carboxyl-containing butadiene-acrylonitrile copolymer latex; (6) a butadiene-acrylonitrile-methacrylic acid copolymer is coagulated on to a polyamide fleece impregnated as in (5) and a lacquer of polyurethane ketone applied. Reference has been directed by the Comptroller to Specification 1,076,177.