Conversion of crude copper phthalocyanines into pigments

Claim 1

In a process for converting crude copper phthalocyanines into a pigmentary form by sulfuric acid treatment of finely particled copper phthalocyanines, which have crystallized irregularly and are heavily agglomerated, and which have a primary particle size of less than 0.1μ and are obtained by grinding crude copper phthalocyanines in a ball mill in th absence of grinding aids, the improvement wherein the ground material is introduced into sulfuric acid of from 50 to 75% strength by weight in the presence of from 0.5 to 7% by weight, based on the crude copper phthalocyanine, of one or more basic copper phthalocyanines of the formula ##STR21## or mixtures thereof, where CuPc is an n-valent copper phthalocyanine radical, R 1 is hydrogen or alkyl of 1 to 4 carbon atoms, A is saturated, linear or branched alkylene of 2 to 6 carbon atoms, R 2 is alkyl of 1 to 20 carbon atoms, alkoxyalkyl of a total of 3 to 12 carbon atoms or cycloalkyl of 6 to 8 carbon atoms, R 3 is hydrogen, alkyl of 1 to 4 carbon atoms or cycloalkyl of 6 to 8 carbon atoms or the group ##STR22## ##STR23## is a saturated heterocyclic 5-membered, 6-membered or 7-membered ring or a saturated 6-membered heterocyclic ring which may additionally contain an oxygen, sulfur or nitrogen atom as a ring member, ##STR24## is ##STR25## and n is from 1 to 6, and the mixture is kept at from room temperature to 100° C. until the pigment has acquired optimum tinctorial strength, and the pigment is then separated from the sulfuric acid and isolated.