Patent GB-1108365-A (GB)
Title: Process for producing microporous materials
IPC: C08J9/28
Filed: 1965-06-18
Abstract: Microporous sheet materials are produced by applying to a substrate a composition containing at least one polymer, a solvent for the polymer and a non solvent for the polymer which is miscible with the solvent and is present in an amount equal to 50 - 95% by weight of the amount required to gel the polymer composition at the temperature of application, coagulating the polymer composition by reducing the temperature of the composition removing the solvent from the coagulated polymer while maintaining the polymer in the coagulated state and then removing the non solvent therefrom, the polymer having a secant modulus at 5% elongation of at least 600 pounds per square inch during the removal of the solvent or non solvent.  The composition may be applied to the substrate at 25 DEG  - 65 DEG C and the polymer coagulated by treating the substrate at 0 DEG -15 DEG C. with a non solvent for the polymer that is miscible with the solvent. The solvent may be removed from the substrate by washing and the non solvent by evaporation.  The polymer may be a vinyl addition polymer, a polyamide, polyurea, a polyesteramide or polyester but is preferably a polyurethane prepared by the reaction of a polyalkylene ether glycol having O3 - C12 alkylene segments and a molecular weight of 300-5,000 or a hydroxyl-terminated polyester produced from an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or lower alkyl ester or ester forming derivatives thereof with a glycol, e.g. a polyalkylene glycol, cyclohexanediol or xylylene glycol, with an aromatic, aliphatic or cycloaliphatic diisocyanate.  The polyurethane may be chain extended by the use of hydrazine, ethylene diamine, hexamethylene diamine, dimethyl piperazine, 1, 4-diamiopiperazine, compounds having the formula NH2-R-N1-R-NH2 in which R is an alkylene group containing 1 - 4 carbon atoms and R1 is an alkyl group containing 1 - 4 carbon atoms, 4-methyl-m-phenylene diamine, m-phenylene diamine or 41 41 diamino-diphenyl-methane.  Mixtures containing polyurethanes with up to 50% by weight of polyvinyl chloride may be used.  Suitable solvents are amides, e.g. N, N-dimethyl formamide, esters, ethers, alcohols, ketones, sulphones and phenols and suitable non solvents are water, glycol monoethyl ether, ethylene glycol, glycerol, 1, 1, 1-trimethylol propane, methanol, ethanol, hexane, octane, benzene, petroleum naphtha, toluene chloroform and tetrachloroethylene.  The treating composition may also contain an extender pigment, e.g. finely divided silica, carbon black or calcium carbonate.  The substrate may be a woven twill, drill or duck, jersey, tricot or knitted material or felt or needle punched porous batt made from polyamide, polyester, polyesteramide, acrylic, viscose rayon, wool, cotton or glass fibres or an impervious substrate, e.g. glass or stainless steel, the microporus coating being subsequently stripped from the substrate. The micropoous materials produced may be used for making upholstery, luggage, handbags, gloves, boots, shoe uppers or clothing.ALSO:Microporous sheet materials are produced by applying to a substrate a composition containing at least one polymer, a solvent for the polymer and a non solvent for the polymer which is miscible with the solvent and is present in an amount equal to 50 - 95% by weight of the amount required to gel the polymer composition at the temperature of application, coagulating the polymer composition by reducing the temperature of the composition removing the solvent from the coagulated polymer while maintaining the polymer in the coagulated state and then removing the non solvent therefrom, the polymer having a secant modulus at 5% elongation of at least 600 pounds per square inch during the removal of the solvent or non solvent.  The composition may be applied to the substrate at 25 DEG - 65 DEG C and the polymer coagulated by treating the substrate at 0 DEG  - 15 DEG C with a non solvent for the polymer that is miscible with the solvent.  The solvent may be removed from the substrate by washing and the non solvent by evaporation.  The polymer may be a vinyl addition polymer, a polyamide, polyurea, a polyesteramide or polyester but is preferably a polyurethane prepared by the reaction of a polyalkylene ether glycol having C1 - C19 alkylene segments and a molecular weight of 300 - 5,000 or a hydroxyl-terminated polyester produced from an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or lower alkyl ester or ester forming derivatives thereof with a glycol, e.g. a polyalkylene glycol, cyclohexanediol or xylylene glycol, with an aromatic, aliphatic or cycloaliphatic diisocyanate. The polyurethane may be chain extended by the use of hydrazine, ethylene diamine, hexamethylene diamine, dimethyl piperazine, 1, 4-diamiopiperazine, compounds having the formula: <FORM:1108365/D1-D2/1> in which R is an alkylene group containing 1 - 4 carbon atoms and R1 is an alkyl group containing 1 - 4 carbon atoms, 4-methyl-m-phenylene diamine, m-phenylene diamine or 4, 41 diamino-diphenyl-methane.  Mixtures containing polyurethanes with up to 50% by weight of polyvinyl chloride may be used.  Suitable solvents are amides, e.g. N, N-dimethyl formamide, esters, ethers, alcohols, ketones, sulphones and phenols and suitable non solvents are water, glycol monoethyl ether, ethylene glycol, glycerol, 1, 1, 1-trimethylol propane, methanol, ethanol, hexane, octane, benzene, petroleum naphtha, toluene, chloroform and tetrachloroethylene.  The treating composition may also contain an extender pigment, e.g. finely divided silica, carbon black or calcium carbonate.  The substrate may be a woven twill, drill or duck, jersey, tricot or knitted material or felt or needle punched porous batt made from polyamide, polyester, polyesteramide, acrylic, viscose rayon, wool, cotton or glass fibres.  The microporous materials produced may be used for making upholstery, luggage, handbags, gloves, boots, shoe uppers or clothing.