Iron blue pigment, process for making the same and use

US4378995A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Everhard Gratzfeld · Wesseling, DE
• Eva Clausen · Cologne, DE
• Helmut Reinhardt
• Hans Schaefer · Hanau, DE

Key dates

• Filing date: Oct 6, 1981
• Grant date: Apr 5, 1983
• Expiry date: Oct 6, 2001

Classification

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

Abstract

Iron blue pigment (DIN 55 906) is produced by white paste precipitation and subsequent oxidation of the white paste. Alakli or alkali metal ions i.e. sodium and potassium ions, cyanide or complex iron cyanide ions and iron ions are used as raw materials. The iron blue pigment according to the invention is characterized by a potassium content of 0.5-4.5% by weight, preferably 0.5-2.0% by weight, a sodium content of 0.2-1.0% by weight, an ammonium content of 2.0-4.5% by weight, preferably 3.0-4.5% by weight, a coloring power in accordance with DIN 53 204 and DIN 53 234 of 5-15% above the Vossen Blue 705 Standard and the following color intervals (determined in accordance with DIN 53 204 and DIN 53 234 in conjunction with DIN 6174, in relation to Vossen Blue 705 as standard): PA2 .DELTA.L: -0.7 to -1.5 PA2 .DELTA.a: -0.5 to 1.5 PA2 .DELTA.b: -0.6 to -2.3 PA2 .DELTA.C: +0.5 to 2.0 In order to save potassium ions, the white paste precipitation of the iron blue pigment according to the invention is carried out in two phases, potassium ions being used as alkali ions in the first phase and sodium ions in the second phase. After removal of the reaction salts and addition of ammonium salts, …