Preparation of thermally stable lead chromate pigments

US4530725A · kind A · utility

Assignees

• BASF Farben · DE
• Fasern Aktiengesellschaft · DE

Inventors

• Werner Ostertag · Havelsee, DE
• Peter Dimroth · Ludwigshafen, DE
• Henning Wienand · Neulußheim, DE
• Egon Liedek · Eßlingen, DE
• Helmut Knittel · Ludwigsburg, DE
• Gunter Etzrodt · Stuttgart, DE

Key dates

• Filing date: Jun 28, 1984
• Grant date: Jul 23, 1985
• Expiry date: Jun 28, 2004

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/37
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Thermally stable lead chromate pigments or pigments containing lead chromate, which have high color strength and are provided with a precipitated coating containing silicon dioxide, are prepared by a process in which an aqueous pigment suspension is mixed once or several times with an aqueous MgSiF.sub.6 solution, the pH being maintained at 4.5-9.5 and the temperature at 50.degree.-95.degree. C., and the pigment is then separated off and worked up, these steps being carried out in a conventional manner.