Nacreous pigments

US4482389A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Klaus-Dieter Franz · Kelkheim, DE
• Klaus Ambrosius · Frankfurt, DE
• Reiner Esselborn · Darmstadt, DE
• Manfred Kieser · Darmstadt, DE

Key dates

• Filing date: Sep 22, 1983
• Grant date: Nov 13, 1984
• Expiry date: Sep 22, 2003

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09C2220/106
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Nacreous pigments which have improved stability to weathering and are based on mica flakes coated with metal oxides, are provided with a stabilizing, chromium-containing second coating which comprises a combination of metal salts. To form the second layer, iron and/or manganese are deposited on the starting pigments in the form of the hydroxide, carbonate or phosphate and chromium is deposited on the starting pigments in the form of the hydroxide, carbonate or phosphate or as methacrylato-chromium chloride. These are prepared by adding iron and/or manganese and chromium, in the form of salt solutions and at a pH of 2 to 8, to an aqueous suspension of a mica flake pigment coated with metal oxides, precipitating them on the mica flake pigments, and separating off these pigments and drying them.