Verfahren zur Herstellung von Chinacridonpigmenten

Preparation of pigments, mixed crystal pigments or pigment preparations based on linear, optionally substituted quinacridones of formula (I) is by hydrolysing a cyclisation reaction mixture of a dianilinoterephthalic acid of formula (IA) and a polyphosphoric acid (or ester) with water or an aqueous mineral acid solution at 110 degrees C or above and then, depending on the nature of the product (A) directly isolating the pigment; (B) subjecting the pre-pigment to a finishing treatment, optionally after adding an organic solvent, and then isolating it; (C) finely dividing the coarse crystalline crude pigment and then isolating it; or (D) subjecting the finely-divided pre-pigment to a finishing treatment, optionally after adding a solvent, and then isolating it. In the formulae, R , R = H, Cl, Br or F or 1-4C alkyl, 1-4C alkoxy, carbonamido (optionally substituted by 1-6C alkyl) or a phenoxy- or aryl-ring optionally substituted by further aromatic, aliphatic or heterocyclic rings.