Heat-stable diketopyrrolopyrrole pigment mixtures

Abstract

The present invention relates to a process for the preparation of a mixture comprising at least two structurally different diketopyrrolopyrrole pigments of formula (1) wherein Aand Aare each independently of the other an aromatic or heteroaromatic radical, by reacting a succinic acid ester with at least one unsubstituted or substituted aromatic or heteroaromatic nitrile, which process comprises carrying out the reaction in the presence of at least one compound of formula (2) wherein A is an aromatic or heteroaromatic radical, Ris hydrogen, halogen, methyl, methoxy, —CFor —CN, Ris a linear or, from Cupwards, optionally branched C-C3alkyl, C-Caryl or C-C2aralkyl radical, X is —S—, —O—, —CRR'—, —COO—, —CONR—, —SO—, SO—, —SONR— or —NR— and Rand R′ are each independently of the other hydrogen or a linear or, from Cupwards, optionally branched C-Calkyl, C-Caryl or C-Caralkyl radical, to the use of such a mixture in the coloring of organic material and in cosmetics, and also to novel diketopyrrolopyrrole pigment mixtures