Process for the production of iron oxide yellow pigments

US5185141A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Bernd Krockert · Wesel, DE
• Helmut Printzen · Krefeld, DE
• Hans-Peter Biermann · Krefeld, DE
• Hans-Ulrich Hofs · Krefeld, DE

Key dates

• Filing date: Feb 26, 1990
• Grant date: Feb 9, 1993
• Expiry date: Feb 26, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/65
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Low-silking iron oxide yellow pigments having improved color qualities are produced by a novel method which utilizes both precipitation process and the Penniman process. Pigments are nucleated and grown by precipitation to achieve multiplication factor of 2.5 to 7 and additional pigment growth is carried out by the Penniman process.