Preparation of phthalocyanine pigments

Abstract

This invention relates to an improved process for preparing metal phthalocyanine pigments comprising (a) heating at a temperature of about 150.degree. C. to about 200.degree. C. a mixture comprising (i) a phthalocyanine-forming material based on phthalic acid, (ii) at least about 25 mole percent, relative to the phthalocyanine-forming material (i), of a metal donor, (iii) at least about 100 mole percent, relative to the phthalocyanine-forming material (i), of a nitrogen donor, (iv) 1 to about 20 percent by weight, relative to the phthalocyanine-forming material (i), of a catalyst, and (v) about 250 to about 400 percent by weight, relative to the phthalocyanine-forming material (i), of a di(C.sub.1 -C.sub.3 alkyl) phthalate solvent; and (b) isolating the metal phthalocyanine pigment.

Dependencies are inferred from the claim text.