Method for making grey-black inclusion pigments

US5205866A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Akos Kiss · Alzenau, DE
• Dietrich Speer · Hanau, DE
• Peter Kleinschmit · Hanau, DE
• Jenny Horst · Gelnhausen, DE

Key dates

• Filing date: Mar 12, 1992
• Grant date: Apr 27, 1993
• Expiry date: Mar 12, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/60
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Gray-black inclusion pigments are made using zirconium silicate as the encasing substance and carbon black particles as the inclusion phase by annealing a mixture of zirconium dioxide, a source for silicon dioxide, carbon black and mineralizers under reducing conditions at 900.degree.-1400.degree. C. The process uses zeolites with an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio of more than 4, preferably more than 10, as the SiO.sub.2 source. The depth of the color can be increased by also using an adhesion agent, especially silicon oil. The use of the zeolites facilities the employment of different zirconium dioxide qualities and permits the production of pigments with higher carbon black inclusion rates.