Gray interference pigment and process for producing the same

• US 5,693,134 A
• Filed: 12/29/1994
• Issued: 12/02/1997
• Est. Priority Date: 12/29/1994
• Status: Expired due to Term

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Stephens, Alfred
• Primary Examiner(s): Marcheschi, Michael
• Application Number:
  US08/365,931
• Time in Patent Office: 1,069 Days
• Field of Search: 106/415, 106/436, 106/440, 106/480, 106/903, 106/441, 106/417, 106/DIG. 3, 428/357, 428/363, 428/402, 428/403, 428/404, 427/212, 427/214, 427/215, 427/218, 427/217, 427/419.2, 427/419.3, 501/17, 501/14
• US Class Current: 106/415
• CPC Class Codes: C01P 2006/62 L* (lightness axis)
• CPC Class Codes: C01P 2006/63 a* (red-green axis)
• CPC Class Codes: C01P 2006/64 b* (yellow-blue axis)
• CPC Class Codes: C08K 9/02 Ingredients treated with inorganic substances
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 2200/1004 the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2
• CPC Class Codes: C09C 2200/102 the core consisting of glass or silicate material like mica or clays, e.g. kaolin
• CPC Class Codes: C09C 2200/1054 the core consisting of a metal
• CPC Class Codes: C09C 2200/1058 comprising a protective coating on the metallic layer
• CPC Class Codes: C09C 2200/1087 the core consisting of bismuth oxychloride, magnesium fluoride, nitrides, carbides, borides, lead carbonate, barium or calcium sulfate, zinc sulphide, molybdenum disulphide or graphite
• CPC Class Codes: C09C 2200/301 Thickness of the core
• CPC Class Codes: C09D 5/36 Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre
• CPC Class Codes: Y10S 106/03 Mica
• CPC Class Codes: Y10T 428/29 Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
• CPC Class Codes: Y10T 428/2911 Mica flake
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

An interference pigment comprising a platelet-shaped substrate coated with titanium dioxide and additionally oxidic compounds of copper and manganese, whereby the pigment powder color is dark gray.

Claims

1. An interference pigment comprising a platelet-shaped substrate coated with titanium dioxide and a mixed metal oxide of copper and manganese of the formula Cu_x Mn_3-x O₄ where x is 1.4 or 1.5.

2. The pigment of claim 1, wherein the mixed metal oxide of copper and manganese is present in an amount of 2.5. to 20 by weight based on the platelet-based substrate.

3. The pigment of claim 1, wherein the copper and manganese in the mixed metal oxide is present in a molar ratio of from 2:

1 to 1;

2.

4. The pigment of claim 1, wherein the titanium dioxide is in an anatase modification.

5. The pigment of claim 1, wherein the titanium dioxide is in a rutile modification.

6. The pigment of claim 1, wherein the platelet-shaped substrate is mica, synthetic mica, glass flakes, ceramic flakes or pearl luster pigments.

7. The pigment of claim 1, wherein the substrate is SnO₂ coated mica.

8. A process for producing interference pigments according to claim 1 comprising forming a mixed metal oxide of copper and manganese on a TiO₂ coated platelet-shaped substrate, by simultaneously or in succession adding a water-soluble copper salt and manganese salt to an aqueous suspension of a platelet-shaped substrate while the substrate is being coated with titanium salt or after it has been coated with titanium salt such that the oxide is deposited on the substrate.

9. The process of claim 8, wherein said pigments are calcined at 500°

C. to 750°

C.

10. A paint, plastic, engobe, glaze, enamel or ceramic material comprising a dark gray powder pigment, wherein the pigment is a pigment according to claim 1.

11. The pigment of claim 1, wherein the platelet-shaped substrate is a synthetic platelet-shaped substrate.

12. The process of claim 8 further comprising separating, washing, drying and calcining in air the substrate after depositing of the oxide.

13. The pigment of claim 1, wherein the pigment has a dark gray color in powder form.