GB466042A - Process for the manufacture of highly dispersed pigments - Google Patents

Abstract

Metal-containing phthalocyanine pigments are dispersed, with simultaneous softening of the grain and improvement of the clarity and intensity of the shade, by mixing or milling them with dispersing agents in presence of water. The dispersion may be effected at elevated temperature and, if desired, under pressure, and the pigment is preferably subjected to a preliminary dispersion by addition of water to its solution in acid, e.g. concentrated sulphuric acid. A portion of the dispersing agent used may be subsequently removed. The dispersing agents are preferably also wetting agents, such as turkey red oil, condensation products of higher fatty alcohols, such as oleyl alcohol, with ethylene oxide or glycide, sulphonated fatty alcohols, naphthalene sulphonic acids and their condensation products with formaldehyde, sulphonated mineral oils and sulphite waste liquor. They may be used alone or with water soluble organic compounds such as glycerol, polyglycerol or pyridine. The following examples are specified: (1) equal weights of copper phthalocyanine and a condensation product of oleyl alcohol (1 mol.) with ethylene oxide (20 mols.) are finely ground together and pasted with water to obtain a dispersion containing 10 per cent of dyestuff and this dispersion is incorporated in (a) a solution of acetylcellulose in acetone and alcohol, the mixture being applied as a thin layer on a glass plate to obtain a transparent blue film, or (b) a mixture obtained from solutions of aluminium sulphate, sodium carbonate and barium chloride after washing out the soluble salts, the mass being then filtered and sized to obtain a preparation for use in printing wallpaper; (2) copper phthalocyanine, precipitated by water from its solution in concentrated sulphuric acid and washed until neutral, is finely ground with an equal weight of the condensation product used in (1) in presence of water to obtain a 10 per cent dyestuff paste which is incorporated in (a) a cuprammonium cellulose or viscose spinning solution to be spun into lustred blue threads, fast to rubbing, washing and light, (b) a mixture of tragacanth, albumen and water to obtain a preparation for printing on cotton, regenerated cellulose artificial silks, wool or natural silk, (c) a mixture of alcohol, the acetal from formaldehyde (1 mol.) and glycerol (1 mol.) and a solution of acetylcellulose in a mixture of the said acetal and alcohol to obtain a similar printing preparation, or (d) a diluted ammoniacal solution of casein with an addition of turkey red oil to obtain a covering dye preparation for leather. Specifications 435,539 and 435,614 are referred to.