Preparation of pigmentary form of quinacridone pigments

Claim 1

A process of preparing pigmentary grade quinacridone from crude quinacridone consisting essentially of a quinacridone or mixture of quinacridones of the formula ##STR5## and mixtures thereof, with 0 to 75 weight percent of unsubstituted quinacridone and 0 to 15 wt. % of a quinacridone of the formula ##STR6## where R 1 , and R 2 are fluorine, chlorine, bromine, methyl or methoxy; R 7 , R 9 , and R 10 are hydrogen or chlorine; R 3 , R 4 , R 5 , and R 6 are hydrogen, fluorine, chlorine, bromine, methyl, or methoxy; 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 by converting the crude quinacridone to a low crystallinity aggregated form, followed by milling the low crystallinity quinacridone in a water miscible organic liquid which is effective in improving the crystallinity of quinacridone particles containing up to an equal amount of water present in an amount sufficient to give a fluid slurry and recovering a pigmentary product.