| 摘要 |
<p>A leather substitute is manufactured by preparing a coating solution by admixing a 5 to 50 per cent by weight solution of at least one polymer containing at least 60% by weight of polyurea elastomer, the solvent being miscible with an alcohol and water but being a nonsolvent for polyamide, with a 5 to 25% by weight alcoholic solution of a polyamide in the dry weight ratio of 1:1/20 to 1, coating the colloidal or suspended admixture thus obtained onto a fibrous substrate, and subsequently treating the coated substrate by immersion in water to form a product having a microporous coating. Again, the leather may be produced by mixing solutions of a polyurea elastomer and a polyamide, each in a solvent for it but non-solvent for the other, the solvents being compatible with each other and also miscible with water, applying the suspended admixture on to a fibrous substrate, which may be pretreated with polymer, and subsequently immersing the coated substrate in water to coagulate the coating. The polyurea elastomer may be obtained by reacting a reaction intermediate of a polyalkylene ether glycol or polyester-glycol having an average molecular weight of 400 to 5000 and an excess of an organic diisocyanate with an organic diamine. The solvent for the polymer may comprise N, N-dimethylformamide, N, N-dimethyl acetamide, dimethyl sulphoxide, or tetrahydrofuran acetonitrile. The polyamide may be a copolyamide, e.g. of nylon 6 and nylon 6, 6, or a N-alkoxymethylated polyamide. The alcohol may comprise one, or mixed alcohols, selected from the lower aliphatic alcohols having 1 to 6 carbon atoms. The polyurea elastomer may be mixed with up to 40% of a compound which is compatible with the polyurea elastomer and is substantially soluble in the solvent for the polyurea elastomer, the compound may be a vinyl polymer or copolymer selected from polyvinyl chloride, polyacrylonitrile and a copolymer of vinyl chloride or methacrylonitrile and acrylonitrile, cellulose acetate or acetate-butyrate, epoxy resin or nitrile rubber. The solution of polymer containing the polyurea elastomer may be admixed with water or alcohol, or a mixture thereof, or alcohol in the form of solvent for polyamide to obtain a substantially colloidal or suspended solution. The fibrous substrate may comprise a fabric, a non-woven fabric, a mat, and/or paper, or a non-woven mat previously treated with a solution or emulsion of an elastomer or synthetic resin such as a polyurea, polyacrylic or acrylonitrile-butadiene or chloroprene rubber, e.g. by impregnating it with a solution of an elastomer, the elastomer being coagulated in a liquid which is a non-solvent for the elastomer and is miscible with the solvent for the elastomer. The polyamide solution may have a content of calcium chloride in a concentration of 5 to 25% by weight. The leather substitute may be embossed and then spray coated or dressed by means of conventional procedures.</p> |
