Patent ID: 6860934

Claim:
A process for the production of a β type copper phthalocyanine pigment having an average primary crystal diameter of 80±40 nm and a primary crystal aspect ratio of 2.0±1.0 and having a crystallite diameter of 22±5 nm in the direction perpendicular to a monoclinic β (200) plane, a crystallite diameter of 27±5 nm in the direction perpendicular to a β (001) plane and a crystallite diameter of 15±5 nm in the direction perpendicular to a β (010) plane, which process comprises, the step (A) of dry-milling a crude copper phthalocyanine having a purity, based on a sulfuric acid dissolution method, of 97 to 100% and a primary crystal diameter of 0.5 to 100 μm at a temperature of 180 to 50° C., to prepare an α/β mixed crystal type copper phthalocyanine having an α ratio of 5 to 35%, and the step (B) of treating the dry-milled product obtained in the step (A) in a water-miscible organic solvent.