Heat-stable iron oxide black pigments, processes for their production and their use

US5055136A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Jurgen Wiese · Krefeld, DE
• Gunter Buxbaum · Krefeld, DE
• Peter Kresse · Krefeld, DE

Key dates

• Filing date: Jun 14, 1989
• Grant date: Oct 8, 1991
• Expiry date: Jun 14, 2009

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/60
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A heat-stable iron oxide black pigment resistant to hydrothermal treatment in air at temperatures above 180.degree. C. and which has a specific BET surface of 0.5 to 5 m.sup.2 /g is useful as a coloring agent for building materials, paints, cements, bricks and so forth and is prepared by reacting an aqueous solution of FeOOH, iron (II) salts and alkalis at elevated temperature and precipitating iron oxide from the solution with Na.sub.2 CO.sub.3 at temperatures in the range from 80.degree. C. to the boiling point of the solution.