OXIDATION METHOD FOR PRODUCING QUINACRIDONE PIGMENT

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a highly pure non-substituted or substituted quinacridone pigment which has a smaller particle diameter and does not need a mechanical crushing process by oxidizing the salt of the corresponding 6,13-dihydroquinacridone. SOLUTION: This method for producing a specific non-substituted or substituted quinacridone or the solid solution of the quinacridone comprises a process for oxidizing the salt of the corresponding 6,13-dihydroquinacridone in the presence of an aqueous base and a catalyst in a reaction medium containing an oxygen-containing gas mixture and a polyalkylene glycol or its derivative, a process for precipitating the produced non-substituted or substituted quinacridone, and a process for recovering the non-substituted or substituted quinacridone.