Abstract: A method for preparing a pigment composition for a plastics colorant is disclosed. The pigment composition is prepared by mixing a press cake of the pigment with a liquid containing a selected type of dispersant before the resulting slurry is dried. Thus prepared pigment composition has improved dispersibility in a thermoplastic or thermoset resin and greatly reduces the filter pressure rise in the molding systems for preparing masterbatches or various plastic compositions for molding, fiber, film and sheet.

Abstract: This invention relates to a continuous process for preparing perylenes by (a) continuously mixing a melt of the leuco form of a perylene tetracarboxylic diimide obtained by alkaline fusion of naphthalimide with a continuous water-containing stream containing (1) 2 to 50 parts of water per part of melt, (2) 0 to X1 moles of oxidizing agent per mole of the leuco form, (3) 0 to Y1 parts by weight of processing additives, based on the leuco form, and (4) 0 to Z1 parts by weight of an acid, based on the leuco form of the perylene tetracarboxylic diimide, to form a slurry; and (b) optionally mixing the slurry in one or more continuous or batchwise steps with a second stream containing (1) 0 to 10 parts by weight of water, based on the slurry, (2) 0 to X2 moles of oxidizing agent per mole of the leuco form of the perylene tetracarboxylic diimide, with the proviso the total of X1 and X2 represents at least the molar amount of oxidizing agent theoretically needed to oxidize all of the leuco form of the perylene tetr