Process for producing transparent pigmentary quinacridones by acid swelling of premilled subpigmentary quinacridones in the presence of an organic liquid

摘要

A process for preparing transparent, pigmentary quinacridone compounds and solid solutions thereof comprises combining a premilled, sub-pigmentary powder containing at least one unsubstituted or substituted quinacridone or a derivative thereof with a sufficient amount of moderately concentrated sulfuric acid to form a slurry, then agitating this slurry in the presence of an organic liquid which is immiscible or only partially miscible with the slurry and which is effective in deagreggating and improving the crystallinity of the pigment, for an effective length of time to convert the sub-pigmentary unsubstituted or substituted quinacridone or solid solution thereof to a transparent, pigmentary form.