Improvements in the coating of leather

摘要

A colloidal solution of an ammonium salt of a carboxyl group-containing copolymer of an acrylic or methacrylic acid ester in a mixture of water and an organic solvent miscible with water is used for coating leather. Copolymers are those of methyl, ethyl, propyl or butyl esters of acrylic or methacrylic acid with acrylic, methacrylic, maleic or crotonic acids having 5-35 per cent. unesterified carboxyl groups. The organic solvents may be ethyl, methyl, or propyl alcohols, acetone or tetrahydrofurane and the solvent mixture may contain 60-150 parts organic solvent per 100 parts copolymer. The resulting solutions may contain aqueous colloidal solutions of casein, albumen, or pectin, or water dilutable leather pigment finishes containing a pigment and hardenable or non-hardenable film-forming binding agents, e.g. casein, shellac, carnauba wax, or nitrocellulose. Drying oils or sulphonated castor oil plasticizer may be added to the solutions. In examples:-(1) Iron oxide red and water are added to a colloidal solution of the ammonium salt of a copolymer of ethyl acrylate and acrylic acid in ethyl alcohol and water, and the resulting mixture after homogenization is diluted with water; (2) a colloidal solution of the ammonium salt of a copolymer of ethyl methacrylate and methacrylic acid in methyl alcohol and water is mixed with 20 per cent. aqueous casein and linseed oil, and the mixture diluted; (3), (5), (6) an aqueous solution of casein, borax, Turkey red oil and iron oxide red is mixed with a colloidal solution of an ammonium salt of a copolymer of methyl or ethyl methacrylate and acrylic or methacrylic acid in methyl or ethyl alcohol and water.