| abstract |
Pigmentary grade quinacridone pigments are prepared from crude quinacridone by conversion to aggregated low crystallinity quinacridones followed by milling the aggregated low crystallinity quinacridone in the presence of a liquid which wets the pigment and can improve the crystallinity of quinacridone at 10° to 60° C. Suitable quinacridones include ##STR1## and mixtures thereof with up to 15 wt. % of ##STR2## where R 1 , R 2 , R 3 , R 4 , R 5 R 6 are hydrogen, fluorine, chlorine, bromine, methyl or methoxy; R 7 , R 9 and R 10 are hydrogen or chlorine; and R 8 is hydrogen, chlorine, bromine, nitro, alkyl groups of 1 to 5 carbon atoms, alkoxy groups of 1 or 2 carbon atoms or benzoylamino, and m is an integer of from 1 to 4. |