Spinel black pigments based on copper-chromium-manganese mixed oxides, a process for their preparation and their use

• US 5,250,112 A
• Filed: 11/20/1992
• Issued: 10/05/1993
• Est. Priority Date: 12/05/1991
• Status: Expired due to Fees

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Wussow, Klaus, Rade, Dieter, Messer, Dieter, Mansmann, Manfred, Kuske, Peter
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): GALLO, CHRISTOPHER
• Application Number:
  US07/979,769
• Time in Patent Office: 319 Days
• Field of Search: 106/453, 106/480
• US Class Current: 106/453
• CPC Class Codes: C01G 45/006 Compounds containing, besides manganese, two or more other elements, with the exception of oxygen or hydrogen manganates, manganites or permanganates C01G45/12
• CPC Class Codes: C01P 2002/32 spinel-type (AB2O4)
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C01P 2006/62 L* (lightness axis)
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: C09C 1/00 Treatment of specific inorganic materials other than fibrous fillers tenebrescent materials C09K9/00; luminescent materials C09K11/00; Preparation of carbon black

Abstract

Spinel black pigments are prepared by annealing oxides, hydroxides or carbonates of copper, chromium and manganese and grinding the product. The manganese-yielding component is Mn₃ O₄.

Claims

1. Black pigments with spinel structure based on copper-chromium-manganese mixed oxides having a copper content of from 13 to 25% by weight, a chromium content of from 22 to 41% by weight, and a manganese content of from 7 to 36% by weight, characterized in that they have brightness values L* in the CIELAB Colour System of from 57 to 61, determined on black pigments incorporated in lacquers after they have been mixed with five times their quqntity of titanium dioxide white pigment wherein Mn₃ O₄ is used to provide the manganese.

2. Black pigments as claimed in claim 1, having a copper content of 15-22% by weight, a chromium content of 25-36% by weight, and a manganese content of 14-30% by weight.

3. A process for the preparation of spinel black pigments, comprising annealing a mixture of oxides, hydroxides or carbonates of copper, chromium and manganese, optionally with the addition of mineralizing agents, at temperatures of from 750°

to 900°

C. and grinding and optionally washing and drying the furnace products, wherein the manganese yielding component is Mn₃ O₄.

4. A process according to claim 3, wherein the Mn₃ O₄ component has been prepared by the oxidation of manganese(II) compounds from solution.

5. Spinel black pigments produced by the process as claimed in claim 3.