GB946053A - Pigments - Google Patents

Abstract

A pigment which is very finely dispersable in aqueous and non-aqueous media is produced by treating the pigment with a surface active alkylene oxide addition product which dissolves clearly at a concentration of 1% in distilled water at 0 DEG C., if desired with the addition of 1% of an addition product of 1 mol. nonyl phenol and 10 mols. ethylene oxide, and the clear 1% aqueous solution of which becomes cloudy on the addition of 10% anhydrous sodium sulphate and/or on heating to a temperature of up to 70 DEG C., then adding an electrolyte to the mixture whereby the alkylene oxide addition product is deposited on the pigment surface; and the pigment thus obtained is then separated. In examples the process is applied to yellow iron oxide and to green chromium oxide. The electrolyte which is added may be a halide, sulphate or phosphate; the preferred example is sodium sulphate. Sedimentation agents such as polyacrylamide or ammonium polyacrylate, filter aids such as vinyl methyl ether, grinding assistants such as sodium sulphate, and additives to prevent caking of the particles such as methyl cellulose, ethyl cellulose, carboxy methyl cellulose, starch and alginates may be added to the pigments. Suitable surface active alkylene oxide addition products are the addition products of ethylene oxide or propylene oxide and alkyl phenols or alkyl naphthols or aliphatic monovalent or polyvalent alcohols, esters, amines, amides, imidazoline or mercaptan addition products or mixtures thereof.ALSO:A pigment which is very finely dispersable in aqueous and non-aqueous media is produced by treating the pigment with a surface-active alkylene oxide addition product which dissolves clearly at a concentration of 1% in distilled water at 0 DEG C., if desired with the addition of 1% of an addition product of 1 mol. nonyl phenol and 10 mols. ethylene oxide, and the clear 1% aqueous solution of which becomes cloudy on the addition of 10% anhydrous sodium sulphate and/or on heating to a temperature of up to 70 DEG C., then adding an electrolyte to the mixture whereby the alkylene oxide addition product is deposited on the pigment surface; and the pigment thus obtained is then separated. In examples the process is applied to azo-pigments, yellow iron oxide, green chromium oxide, and copper phthalocyanine. The electrolyte which is added may be a halide, sulphate or phosphate; the preferred example is sodium sulphate. Sedimentation agents such as polyacrylamide or ammonium polyacrylate, filter aids such as vinyl methyl ether, grinding assistants such as sodium sulphate, and additives to prevent caking of the particles such as methyl cellulose, ethyl cellulose, carboxy methyl cellulose, starch and alginates may be added to the pigments. Suitable surface-active alkylene oxide addition products are the addition products of ethylene oxide or propylene oxide and alkyl phenols or alkyl naphthols or aliphatic monovalent or polyvalent alcohols, esters, amines, amides, imidazoline or mercaptan addition products or mixtures thereof.