PROZESS ZUR HERSTELLUNG VON IM WESENTLICHEN REINEM QUINACRIDONPIGMENT IN DER GAMMA PHASE MIT GROSSER PARTIKELGRÖSSE

摘要

An improved process for producing a substantially pure gamma phase a quinacridone pigment or pigment derivative involving preparing an aqueous slurry of a crude quinacridone in the presence of caustic alkali and a non-polar, water immiscible solvent; and heating said slurry at a temperature above about 120° C.