Preparation of pigmentary grade pigment from crude pigment
AssigneeCiba-Ceigy Corporation
InventorEdward E. Jaffe
Life of this patent
Estimating the term…
Abstract
Finished grade pigments are prepared from crude pigment precursors by conversion to aggregated low crystallinity pigment followed by milling the aggregated low crystallinity pigment in water having a pH of from 7 to 14 and from 5 to 25% based on pigment of a separate phase comprising an organic liquid which is effective in growing and improving the crystallinity of the pigment particles. The resulting material is extracted in dilute acid, washed free of acid and dried to produce the final finished grade pigment.
Claims13
A process for the preparation of finished pigment which consists essentially of a quinacridone or quinacridone of the formula ##STR4## and solid solutions or mixtures thereof, with up to 15 wt. % of a quinacridone of the formula ##STR5## where R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are hydrogen, fluorine, chlorine, bromine, methyl or methoxy;
- R.sup.7, R.sup.9, and R.sup.10 are hydrogen or chlorine;
- and R.sup.8 is hydrogen, chlorine, bromine, nitro, alkyl groups of 1 to 5 carbon atoms, alkoxy groups of 1 or 2 carbon toms or benzoylamine, and m is an integer of from 1 to 4, from crude precursors by converting the crude precursor therefor to a low crystallinity aggregated form, followed by milling the low crystallinity pigment in water having a pH from 7 to 14 and from 5 to 25% by weight, based on pigment, of a separate phase comprising an organic liquid which is effective in improving the crystallinity of the pigment particles and recovering a pigmentary grade product.
Dependencies are inferred from the claim text.