Process for the preparation of highly pure halogenated phthalocyanine pigment

US4018791A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Ernst Spietschka · Idstein, DE
• Siegfried Schiessler · Frankfurt am Main, DE
• Wolfgang Tronich

Key dates

• Filing date: Dec 21, 1973
• Grant date: Apr 19, 1977
• Expiry date: Dec 21, 1993

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B67/0017
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of highly pure organic pigments which comprises converting organic dyestuffs having various degrees of purity into dyestuff salts capable of being isolated by means of suitable acids which dissolve the impurities contained in the dyestuff, separating them from the acid, recovering the dyestuffs in pure form from the dyestuff salts by the action of water and subjecting the isolated dyestuff in aqueous organic or aqueous-organic medium to a mechanical fine dispersion. By this process the dyestuff formed by the decomposition of the dyestuff sulfate is obtained in highly pure form and can extremely well be brought into a finely dispersed form so that it can be brought into pigment form already by short-time grinding. During the preparation and isolation of the dyestuff sulfate the sulfuric acid is obtained in such a high concentration that it can be regenerated in an economical manner and any ecological charge is avoided.