Patent GB-1123292-A (GB)
Title: Microporous polyurethanes
Inventor: REISCHL ARTUR
IPC: C08G18/84
Filed: 1967-01-03
Abstract: Microporous supported or unsupported films or foils are prepared by mixing (a) a colloidal solution in a first organic solvent of a high M.W. polyaddition product which alone or in admixture with (e), has a Shore A hardness of greater than 35 and is obtained from a compound having hydroxyl and/or amino groups and a M.W. of 500 to 20,000, 0.03 to 0.60 equivalent per cent of a polyisocyanate, based on the polyaddition product and if desired a chain extender with reactive hydrogen atoms and a M.W. of less than 500, with optionally (b) an additional polyisocyanate and/or formaldehyde or a formaldehyde donor and/or a peroxide and optionally (c) an additional compound reacting with isocyanates, with the second organic solvent which does not dissolve the product (a) but which is miscible with the first organic solvent, has a relative evaporation index greater than that of the first organic solvent and less than 50% by weight of which are absorbed through swelling by the polyaddition product (a) over a period of 24 hours, at least 60% by weight of the quantity of non-solvent required to swell solution (a) being added, spreading this solution on a substrate to form a sheet or film, evaporating subsequently the first and second organic solvents, optionally removing the resulting microporous film from the substrate and optionally transferring the microporous sheet to another porous substrate provided with a non-continuous adhesive layer.  The first organic solvent is suitably acetone, methyl ethyl ketone, tetrahydrofuran, ethyl acetate, methylene chloride or ethylene chloride whilst the second organic solvent is suitably an aliphatic hydrocarbon, alcohol or ether.  Preferably the polyaddition product (a) is based on a polyether or polyester and is made by a one-step or two-step process using chain extenders which may be glycols, diamines, ethanolamine or water.  Additional polymers may be combined with solution (a) to modify handle, elasticity and hardness.  Such polymers are polyvinyl chloride, ethylene/vinyl acetate polymers, styrene/acrylonitrile polymers, butadiene/acrylonitrile polymers, polyacrylates, polymethacrylates, polychlorobutadiene, polycarbonates and polyoxymethylenes. The substrate may be porous or non-porous. When a non-porous support is used, the dry sheet is preferably transferred to porous substrates by the known reversal processes. Suitable substrates are glass or metal plates, silicone rubber matrices, split leather, grain leather, woven or knitted textiles, felts, fleeces, paper or card.  Examples describe the manufacture of coated or laminated products using the direct or reversal process respectively, the substrates used being a fleece of synthetic fibres, split leather or cotton plush.ALSO:Microporous supported or unsupported films or foils are prepared by mixing (a) a colloidal solution in a first organic solvent of a high M.W. polyaddition product which alone or in admixture with (G) has a Shore A hardness of greater than 35 and is obtained from a compound having hydroxyl and/or amino groups and a M.W. of 500 to 20,000, 0.03 to 0.60 equivalent % of a polyisocyanate, based on the polyaddition product and if desired a chain extended with reactive hydrogen atoms and a M.W. of less than 500, with optionally (b) an additional polyisocyanate and/or formaldehyde or a formaldehyde donor and/or a peroxide and optionally (c) an additional compound reacting with isocyanates with a second organic solvent which does not dissolve the product (a) but which is miscible with the first organic solvent, has a relative evaporation index greater than that of the first organic solvent and less than 50% by weight of which are absorbed through swelling by the polyaddition product (a) over a period of 24 hours, at least 60% by weight of the quantity of non-solvent required to swell solution (a) being added, spreading this solution on a substrate to form a sheet or film, evaporating subsequently the first and second organic solvents, optionally removing the resulting microporous film from the substrate and optionally transferring the microporous sheet to another porous substrate provided with a non-continuous adhesive layer.  The first organic solvent is suitably acetone, methyl ethyl ketone, tetrahydrofuran, ethyl acetate, methylene chloride or ethylene chloride whilst the second organic solvent is suitably an aliphatic hydrocarbon, alcohol or ether. Preferably the polyaddition product (a) is based on a polyether or polyester and is made by a one-step or two-step process using chain extenders which may be glycols, diamines, ethanolamine or water. Additional polymers may be combined with solution (a) to modify handle, elasticity and hardness.  Such polymers are polyvinyl chloride, ethylene/vinyl acetate polymers, styrene/acrylonitrile polymers, butadiene/acrylonitrile polymers, polyacrylates, polymethacrylates polychlorobutadiene, polycarbonates, and polyoxymethylenes.  The substrate may be porous or non-porous. When a non-porous support is used, the dry sheet is preferably transferred to porous substrates by the known reversal processes. Suitable substrates are glass or metal plates, silicone rubber matrices, split leather, grain leather, woven or knitted textiles, felts, fleeces, paper or card.  Examples describe the manufacture of coated or laminated products using the direct or reversal process respectively, the substrates used being a fleece of synthetic fibres, split leather or cotton plush.