Titanium dioxide pigment coated with hollow bodies and method for its manufacture

Abstract

A coated titanium dioxide pigment with good opacity and simultaneously good retention for use in decorative laminating paper characterized by a surface coating containing aluminium oxide phosphate and attached hollow bodies, e.g., hollow microbodies. A manufacturing method is characterized in that an aluminium containing component and a phosphorus containing component are first added to a TiO2 suspension, during which time the pH value does not drop below 10. The hollow bodies are subsequently added, followed by addition of at least one acidic component, as a result of which the pH value of the suspension is lowered to the range from about 4 to 9. In an alternative embodiment of the method, the suspension has a pH value of under 4 at the time of addition of the aluminium containing component and a phosphorus containing component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and for further advantages thereof, reference is now made to the following Description of the Preferred Embodiments taken in conjunction with the accompanying Drawings in which:

FIG. 1 is an electron micrograph showing the present invention.

Claims

1. A titanium dioxide pigment comprising: titanium dioxide particles whereby a coating is located on the titanium dioxide particle surface, the coating comprising aluminium phosphate, aluminium oxide and hollow bodies.

2. The titanium dioxide pigment of claim 1 whereby the hollow bodies display an average diameter of about 5 to 1000 nm.

3. The titanium dioxide pigment of claim 1 whereby the aluminium content of the coating is about 1.0 to 9.0% by weight calculated as Al2O3.

4. The titanium dioxide pigment of claim 1 whereby the phosphorus content of the coating is about 1.0 to 5.0% by weight calculated as P2O5.

5. The titanium dioxide pigment of claim 1 wherein: the titanium dioxide pigment particles are contained in decorative laminating paper.

6. The titanium dioxide pigment of claim 1 wherein: the titanium dioxide pigment particles are contained in decorative coating material.

7. A method for manufacturing coated titanium dioxide pigment particles comprising: providing an aqueous suspension comprising uncoated titanium dioxide particles;adding an aluminium-containing component and a phosphorus-containing component;adding a component comprising hollow bodies; andsetting the pH value of the suspension to a value in the range of about 4 to 9.

8. The method of claim 7 wherein: the pH value of the aqueous suspension is at least about 10 and the pH value of the suspension is kept at least about 10 when adding the components.

9. The method of claim 7 wherein: the pH value of the suspension turns to below about 4 when adding the aluminium-containing component and the phosphorous-containing component.

10. The method of claims 7 wherein: the hollow bodies display an average diameter of about 5 to 1000 nm.

11. The method of claim 7 wherein: the sum total of the aluminium compounds added is about 1.0 to 9.0% by weight calculated as Al2O3.

12. The method of claim 7 wherein: the sum total of the phosphorus compounds added is about 1.0 to 5.0% by weight calculated as P2O5.

13. The method of claim 7 further comprising: applying a further aluminium-oxide coating at a pH value of about 4 to 9.

14. The method of claim 13 further comprising: setting the pH value of the suspension to about 5 to 8.

15. The method of claim 14 further comprising: treating the pigment particles with nitrate, wherein the finished pigment contains up to about 1.0% by weight nitrate.

16. The method of claim 14 further comprising: milling the pigment particles with an organic compound.

17. The method of claim 7 wherein in the step of adding an aluminium-containing component and a phosphorus-containing component, the components are added simultaneously.

18. A method for manufacturing coated titanium dioxide pigment particles comprising: providing an aqueous suspension of uncoated titanium dioxide particles, whereby the pH value is at least about 10;adding an aluminium-containing component and a phosphorus-containing component, whereby the pH value of the suspension is kept at least about 10;adding a component comprising hollow bodies;setting the pH value of the suspension to a value in the range of about 4 to 9;applying a further aluminium-containing coating.

19. The method of claim 13 further comprising: adding the titanium dioxide pigment particles to a process for manufacturing decorative laminating paper.

20. The method of claim 19 further comprising: processing the decorative laminating paper to manufacture decorative coating material.