Preparation of β-copper phthalocyanine without milling

Claim 1

In a process for the production of copper phthalocyanine pigment by the steps of preparing a solution of crude copper phthalocyanine in concentrated sulfuric acid of at least 70 weight percent strength, drowning the sulfuric acid solution in water or dilute acid flowing at a velocity in excess of the critical velocity to provide high turbulence and produce a slurry of copper phthalocyanine crystals, and thereafter recovering copper phthalocyanine as a pigment, the improvement, for obtaining copper phthalocyanine having a surface area of at least 40 m 2 /gram in the β phase without milling, wherein intermediate to the drowning and recovery steps the slurry is maintained under high-speed high-shear agitation with an homogenizer at an acid concentration of less than 40 weight percent and at a temperature of less than about 45°C. for about 5-10 minutes in the presence of a. a quantity of a water-immiscible halogenated organic liquid at least equal in weight to the crude copper phthalocyanine employed, said organic liquid being selected from the group consisting of orthodichlorobenzene, trichloroethylene, chloroform, perchloroethylene, carbon tetrachloride and trichloromethane, and b. β-copper phthalocyanine as seed, the particle size thereof being not greater than about 0.05μ and its specific surface area being at least 75 m 2 /gram, the seed being employed in about a 5 weight percent quantity relative to the crude copper phthalocyanine.