Fine division in the preparation of copper phthalocyanine pigments

Abstract

Copper phthalocyanine pigments are finely divided in an ecologically and economically advantageous manner by first of all subjecting crude, coarsely crystalline copper phthalocyanine pigments to dry milling and then wet milling the finely divided prepigments which are obtained in the course of dry milling, in aqueous suspension and with the addition of from 0.1 to 5% by weight, based on the total millbase, of an organic solvent which is inert with respect to the process conditions, on a stirred ball mill which is operated at an energy density of more than 2.5 kW per liter of milling space and a peripheral stirrer speed of more than 12 m/s under the action of grinding media having a diameter of less than or equal to 1 mm. Copper phthalocyanine pigments prepared in this way are particularly suitable as colorants for pigmenting paints, printing inks and plastics.

Dependencies are inferred from the claim text.