Patent GB-895751-A (GB)
Title: Improvements in or relating to a process for the production of pigment preparations
IPC: C09B67/20
Filed: 1959-04-24
Abstract: A process for the production of pigment preparations involving the reduction of the particle size of the subdivided pigment comprises subjecting to mechanical comminution a free-flowing suspension of the water-moist pigment, such as an aqueous presscake of copper phthalocyanine, in a solution of a water-insoluble natural or synthetic polymerization or polycondensation product in an organic solvent and drying the product or, alternatively, precipitating the product with water or other solvent the precipitate formed being filtered off, washed and dried.  The grinding or mechanical comminution may be carried out in a mill of ball or roller type or in a homogenizing machine operating under pressure in which latter case a cooling system is preferably employed.  The rate of homogenization can be accelerated or the homogenizing effect increased by the addition of surface active substances, e.g. higher molecular amines or higher molecular quaternary ammonium salts.  The solution in which the pigment is suspended may be (a) a solution of secondary cellulose acetate, an acrylate-methacrylate copolymer, an acrylonitrile-methacrylate copolymer or collodion cotton in acetone (b) a solution of vinyl chloride-vinyl acetate copolymer, polyvinyl acetate or polystyrene in an acetic acid alkyl ester or (c) a solution of polyvinyl chloride in carbon disulphide and acetone. Several examples are described in all of which the suspension is ground or comminuted until the bulk of the particles is reduced to a size of less than one micron.ALSO:A process for the production pigment preparations involving the reduction of the particle size of the subdivided pigment comprises subjecting to mechanical comminution a free-flowing suspension of the water-moist pigment, such as an aqueous presscake of copper phthalocyanine, in a solution of a water-insoluble natural or synthetic polymerization or polycondensation product in an organic solvent and drying the product or, alternatively, precipitating the product with water or other solvent, the precipitate formed being filtered off, washed and dried. The grinding or mechanical comminution may be carried out in a mill of ball or roller type or in a homogenizing machine operating under pressure in which latter case a cooling system is preferably employed.  The rate of homogenization can be accelerated or the homogenizing effect increased by the addition of surface active substances e.g. higher molecular amines or higher molecular quaternary ammonium salts. The solution in which the pigment is suspended may be (a) a solution of secondary cellulose acetate, an acrylate-methacrylate copolymer, an acrylonitrile-methacrylate copolymer or collodion cotton in acetone (b) a solution of vinyl chloride-vinyl acetate copolymer, polyvinyl acetate or polystyrene in an acetic acid akyl ester or (c) a solution of polyvinyl chloride in carbon disulphide and acetone.  Several examples are described in all of which the suspension is ground or comminuted until the bulk of the particles is reduced to a size of less than one micron.