process for the production of chinacridonpigmenten using moderately concentrated acid

摘要

A process for preparing beta or gamma crystals of linear quinacridone, substituted quinacridone or solid solutions thereof by contacting premilled quinacridone with 45-60% by weight sulfuric acid and 0-10% by weight of a surfactant based on the quinacridone at a weight ratio of acid to quinacridone of 3:1-6:1 to form a slurry, agitating said slurry for a period of time at 45°-75° C., adding water to form a dilute slurry, agitating said dilute slurry for a period of time at 75. degree.-95° C. and separating quinacridone from the liquid of the dilute slurry.