Treatment of leather

摘要

In treating leather to improve its break and resistance to abrasion and scuffing, the leather is coated, e.g. at temperatures between room temperature and 80 DEG C., on its grain side and impregnated, through the corium minor to its junction with the corium major, with a solution, in an organic solvent, of a water-insoluble copolymer of monoethylenically unsaturated molecules comprising: (a) 3.5 to 18.5 mol. per cent of at least one acid selected from acrylic, methacrylic and itaconic acid, (b) 1.5 to 8 mol. per cent of at least one ester of acrylic or methacrylic acid and a saturated, monohydric, aliphatic alcohol having 8 to 18 carbon atoms (c) 10.5 to 43 mol. per cent of at least one methacrylate selected from methyl, ethyl and isobutyl methacrylate, and (d) 32 to 84.5 mol. per cent of at least one ester of acrylic acid and a saturated, monohydric alcohol having 1 to 4 carbon atoms; the total of (a) and (c) being 15 to 45 mol. per cent and the mol. ratio of (b) to (c) being between 1:3.3 and 1:6.7, the balance of said unsaturated molecules, if any, being compatible molecules, e.g. up to 32.5 mol. per cent of at least one of the monomers: acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, styrene and vinyl toluene; said copolymer having an average molecular weight of at least 10,000 and a viscosity not exceeding 20 centipoises, at 25 DEG C., in a 20% solution in said organic solvent. The copolymer may also comprise up to 5 mol. per cent of at least one neutral hydrophilic monomer selected from: hydroxyethyl acrylate, acrylamide methacrylamide and N-methylolacrylamide. Component (b) may be n-octyl acrylate, dodecyl acrylate, octadecyl acrylate or a mixture of tetradecyl, hexadecyl and octadecyl methacrylates. Component (c) is the essential hardening component. The solution may also contain a dye, a pigment and a non-plasticizing oil such as neatsfoot, coconut, sperm or cod oil. The oil may contain neatsfoot monoglyceridyl glycollate, oleic acid, octadecenyl succinic acid anhydride, primary tallow amine, tertiary dodecyl amine or tertiary pentadecyl amine. Specified alcohols, ketones, ethers, ether-alcohols, esters, aromatic and aliphatic hydrocarbons and chlorinated hydrocarbons may be used as solvents. The impregnated leather may be dried at room temperature or at temperatures between 50 and 70 DEG C.ALSO:A water - insoluble copolymer of monoethylenically unsaturated molecules, used for treating leather (see Division C6), comprises: (a) 3.5 to 18.5 mol. per cent of at least one acid selected from acrylic, methacrylic and itaconic acid, (b) 1.5 to 8 mol. per cent of at least one ester of acrylic or methacrylic acid and a saturated, monohydric, aliphatic alcohol having 8 to 18 carbon atoms, (c) 10.5 to 43 mol. per cent of at least one methacrylate selected from methyl, ethyl and isobutyl methacrylate, and (d) 32 to 84.5 mol. per cent of at least one ester of acrylic acid and a saturated, monohydric alcohol having 1 to 4 carbon atoms; the total of (a) and (c) being 15 to 45 mol. per cent and the mol. ratio of (b) to (c) being between 1 : 3.3 and 1 : 6.7, the balance of said unsaturated molecules, if any, being compatible molecules, e.g. up to 32.5 mol. per cent of at least one of the monomers: acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, styrene and vinyl toluene; said copolymer having an average molecular weight of at least 10,000 and a viscosity not exceeding 20 centipoises, determined at 25 DEG C. with a 20% solution in a specified organic solvent. The copolymer may also comprise up to 5 mol. per cent of at least one neutral hydrophilic monomer selected from: hydroxyethyl acrylate, acrylamide, methacrylamide and N-methylol acrylamide. Component (b) may be n-octyl acrylate, dodecyl acrylate, octadecyl acrylate or a mixture of tetradecyl, hexadecyl and octadecyl methacrylates. The components (a), (b), (c) and (d) and, if desired, said compatible and hydrophilic monomers are mixed, and 20% of this mixture and 20% of a toluene-benzoyl peroxide catalyst mixture are mixed with a toluene-cumene mixture, at a temperature between 105 DEG and 110 DEG C. The temperature of the resulting mixture is brought between 108 DEG and 103 DEG C. and the remaining portions of the component and catalyst mixtures are gradually added. A solution of the copolymer in toluene-cumene is thus obtained. Azo-di-isobutyronitrile may be used as a catalyst, instead of benzoyl peroxide.