| abstract |
A process for the production of a pigment composition useful in pigmenting surface coating comprising: n (a) milling a crude copper phthalocyanine blue pigment in the presence of 0-50% (by weight of milled materia) of a salt; and n (b) subsequently treating the milled material with a polar aliphatic solvent; whereby n (c) 8 to 12% by weight, based on crude pigment, of a copper phthalocyanine additive of the formula I ##STR1## wherein CuPc is the residue of copper phthalocyanine, m and n are each an integer of from 1 to 4, and R 1 and R 2 are each an optionally substituted alkyl group, or R 1 and R 2 , together with the N atom to which they are bonded, form a heterocycle, is added to the crude milled pigment prior to, during or after the solvent treatment of step (b); and, (d) the pigment composition is then isolated. |