Process for the production of yellow-brown zinc ferrite pigments

US4681637A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Jakob Rademachers · Krefeld, DE
• Karlheinz Turban · Krefeld, DE
• Gerhard Franz · Marl, DE
• Werner Fuhr · Krefeld, DE
• Bernd Holle · Freiberg, DE

Key dates

• Filing date: Mar 14, 1985
• Grant date: Jul 21, 1987
• Expiry date: Mar 14, 2005

Classification

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

Abstract

A process for the production of an anisometric yellow-brown zinc ferrite pigment comprising homogeneously mixing zinc oxide having a specific BET surface of more than 2 m.sup.2 /g with needle-shaped .alpha.-FeOOH obtained from an iron salt solution by mixing with alkali and subsequently oxidizing in a nucleation and pigment growth stage, the FeOOH having a specific BET surface of about 15 to 25 m.sup.2 /g, an average needle width of about 0.025 to 0.125 .mu.m and an average needle length of about 0.2 to 0.6 .mu.m, annealing the mixture at a temperature of about 700.degree. to 1000.degree. C., cooling and grinding.