Process for the wet granulation of organic pigments in an aqueous system with hydrolysis of acetic anhydride, propionic anhydride or a mixture thereof

摘要

A process for the wet granulation of organic pigment is disclosed which consists in treating under vigorous agitation an aqueous suspension of pigment with acetic anhydride, propionic anhydride or a mixture thereof. Acetic anhydride is used preferentially. After hydrolysis of the anhydride, besides the granules, an aqueous solution of acid or its corresponding salt, directly saleable or re-usable in the chemical industry, is recovered whereby problems related to the recovery of organic solvents are avoided.