Process for preparing metal oxide coated aluminium effect pigments

Patent metadata

Field	Value
Publication number	US-9701844-B2
Application number	US-201314397721-A
Country	US
Kind code	B2
Filing date	May 10, 2013
Priority date	May 22, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

The present invention relates to a process for preparing a colored effect pigment, comprising: (i) coating aluminum-based substrate particles in an aqueous coating medium with at least one metal oxide layer, wherein the metal oxide is selected from a titanium oxide, an iron oxide, or any mixture thereof, (ii) providing a mixture of the coated aluminum-based substrate particles and a particulate inorganic non-metallic material in the aqueous coating medium by adding the particulate inorganic non-metallic material to the aqueous coating medium, and (iii) separating the mixture of the coated aluminum-based substrate particles and the particulate inorganic non-metallic material from the aqueous coating medium and subjecting the separated mixture to a thermal drying step so as to obtain a dry colored effect pigment material.

First claim

The invention claimed is:

1. A process for preparing a coloured effect pigment having an aluminum-based substrate particle and an iron oxide or titanium oxide layer, the process comprising:
(i) coating aluminium-based substrate particles in a liquid aqueous coating medium with at least one metal oxide layer comprising at least one of a titanium oxide and an iron oxide,
(ii) adding a particulate inorganic non-metallic material to the liquid aqueous coating medium to obtain a mixture of the coated aluminium-based substrate particles and the particulate inorganic non-metallic material in the liquid aqueous coating medium,
(iii) separating the particulate mixture of the coated aluminium-based substrate particles and the particulate inorganic non-metallic material from the liquid aqueous coating medium, and
(iv) thermally drying the separated particulate mixture to obtain the coloured effect pigment as a dry material.

2. The process according to claim 1 , wherein the aluminium-based substrate particles comprise an aluminium or aluminium alloy core which is optionally at least partly coated with one or more passivation layers.

3. The process according to claim 2 , wherein the aluminium-based substrate particles comprise a passivation layer and the passivation layer is at least one of a metal phosphate layer and an inorganic oxide layer.

4. The process according to claim 1 , wherein a thickness of the metal oxide layer is such that 1 st order or 2 nd order interference is obtained.

5. The process according to claim 1 , wherein the particulate inorganic non-metallic material is at least one selected from the group consisting of a sheet silicate, a layered silicate, an aluminium oxide, an aluminosilicate, glass, perlite, synthetic mica, and borosilicate glass.

6. The process according to claim 1 , wherein the particulate inorganic non-metallic material added to the liquid aqueous coating medium is not coated.

7. The process according to claim 1 , wherein the particulate inorganic non-metallic material added to the liquid aqueous coating medium is coated with at least one metal oxide layer.

8. The process according to claim 1 , wherein the particulate inorganic non-metallic material is added to the liquid aqueous coating medium during (i) and/or is already present in the liquid aqueous coating medium before (i) is carried out.

9. The process according to claim 1 , wherein the particulate inorganic non-metallic material is added to the liquid aqueous coating medium after (i).

10. The process according to claim 1 , wherein the particulate inorganic non-metallic material is added to the liquid aqueous coating medium in an amount of from 1 wt % to 50 wt %, based on the amount of the aluminium-based substrate particles.

11. The process according to claim 1 , wherein an average particle diameter of the aluminium-based substrate particles and an average particle diameter of the particulate inorganic non-metallic material do not differ by more than 30%.

12. The process according to claim 1 , wherein the mixture of the coated aluminium-based substrate particles and the particulate inorganic non-metallic material is separated from the liquid aqueous coating medium by filtration.

13. The process according to claim 1 , wherein the thermal drying comprises calcination at a temperature of at least 150° C.

14. The process according to claim 1 , further comprising a pigment surface modification wherein the dry coloured effect pigment material is brought into contact with a surface-modifying agent.

Assignees

• Basf Se

Inventors

• Wosylus Aron
• Schmid Raimund

Classifications

• C09C2200/102

  the core consisting of glass or silicate material like mica or clays, e.g. kaolin · CPC title

• C09C3/063

  Coating · CPC title

• C09C1/642 Primary

  treated with inorganic compounds · CPC title

• C09C1/0081

  Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound (C09C1/0015, C09C1/0078 take precedence) · CPC title

• C09C1/0021

  comprising a core coated with only one layer having a high or low refractive index · CPC title