Manufacture of a pigmentary form of .alpha.-indanthrone

US4167634A · kind A · utility

Assignee

• BASF SE

Inventors

• Helmut Hoch
• Heinrich Hiller · Monsheim, DE
• Guenther Bauni · Dudenhofen, DE

Key dates

• Filing date: Feb 3, 1978
• Grant date: Sep 11, 1979
• Expiry date: Feb 3, 1998

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B5/48
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

An .alpha.-indanthrone pigment having improved tinctorial and technological properties is produced by swelling .gamma.-indanthrone in sulfuric acid of from 73 to 80 percent strength by weight at from 20.degree. to 50.degree. C. in the presence of from 0.1 to 20% by weight, based on indanthrone, of a hydroxylammonium salt, a hydrazinium salt, amidosulfonic acid, urea, a salt of urea, formaldehyde or paraformaldehyde or a mixture of these. After precipitation in water which may or may not contain a surfactant, at below 50.degree. C., an .alpha.-indanthrone pigment of high tinctorial strength is obtained, which gives clear and pure colorations and is easily dispersible.