High opacity TiO2 pigment and production method

Abstract

The invention relates to a rutile titanium dioxide pigment for use in decorative laminating papers that yields higher opacity of the papers compared to the prior art, as well as a method for its manufacture. The pigment displays a surface coating that contains aluminium phosphate, aluminium oxide, silicon oxide and titanium oxide. The silicon oxide is precipitated in fluffy form. The coated particles display a BET value of at least 15 m2/g.

Description

Claims

1. Titanium dioxide (TiO2) pigment particles, comprising: a) uncoated rutile TiO2 particles;b) a coating covering the uncoated rutile TiO2 particles, the coating containing aluminum phosphate, aluminum oxide, silicon oxide, and titanium oxide, and where the specific surface area to BET of the coated particles is at least 15 m2/g.

2. The TiO2 pigment particles of claim 1, wherein the aluminum content of the coating is 1.0 to 9.0% by weight calculated as Al2O3.

3. The TiO2 pigment particles of claim 2, wherein the aluminum content of the coating is 2.0 to 8.0% by weight calculated as Al2O3.

4. The TiO2 pigment particles of claim 1, wherein the phosphorous content of the coating is 1.0 to 5.0% by weight calculated as P2O5.

5. The TiO2 pigment particles of claim 4, wherein the phosphorous content of the coating is 1.5 to 4.0% by weight calculated as P2O5.

6. The TiO2 pigment particles of claim 1, wherein the silicon content of the coating is 0.1 to 5.0% by weight calculated as SiO2.

7. The TiO2 pigment particles of claim 6, wherein the silicon content of the coating is 1.0 to 3.0% by weight, calculated as SiO2.

8. The TiO2 pigment particles of claim 1, wherein the titanium content of the coating is 0.1 to 6.0% by weight, calculated as TiO2.

9. The TiO2 pigment particles of claim 1, wherein the specific surface area to BET is 20 to 60 m2/g.

10. The TiO2 pigment particles of claim 9, wherein the specific surface area to BET is 20 to 35 m2/g.

11. The TiO2 pigment particles of claim 1, wherein the TiO2 pigment particles are contained in decorative laminating paper.

12. The TiO2 pigment particles of claim 11, wherein decorative laminating paper is laminated.

13. A method for manufacturing TiO2 pigment particles, comprising the steps: a) providing an aqueous suspension of uncoated rutile TiO2 particles;b) adding an aluminum component and a phosphorous component to the aqueous suspensionc) adding an alkaline silicon component to the aqueous suspension of step b) and at least one pH-regulating component, where one of the pH-regulating components is an acid-reacting titanium component and where the pH of the suspension is set to a value in the range from 4 to 9.

14. The method of claim 13, wherein the pH of the suspension is maintained at a value of at least 10 during step b).

15. The method of claim 13, further comprising; d) adding an aluminum component and a pH-regulating component, while maintaining the pH value of the suspension in the range from 4 to 9, thereby adding an aluminum oxide layer to the pigment particles produced in step c).

16. The method of claim 15, further comprising; e) setting the final pH value of the suspension roughly 6 to 7 using a lye or acid solution, or with an alkaline or acidic salt solution.

17. The method of claim 13, wherein the sum total of the aluminum components added after step a) is 1.0 to 9.0% by weight calculated as Al2O3.

18. The method of claim 17, wherein the sum total of the aluminum components added after step a) is 2.0 to 8.0% by weight calculated as Al2O3.

19. The method of claim 13, wherein the sum total of the phosphorus components added after step a) is 1.0 to 5.0% by weight calculated as P2O5.

20. The method of claim 19, wherein the sum total of the phosphorus components added after step a) is 1.5 to 4.0% by weight calculated as P2O5.

21. The method of claim 13, wherein the sum total of the silicon components added after step b) is 0.1 to 5.0% by weight, calculated as SiO2.

22. The method of claim 21, wherein the sum total of the silicon components added after step b) is 1.0 to 3.0% by weight, calculated as SiO2.

23. The method of claim 13, wherein the sum total of the titanium components added after step b) is 0.1 to 6.0% by weight, calculated as TiO2.

24. The method of claim 15, further comprising; e) treating the pigment with nitrate, wherein the finished pigment contains 0.05 to 1.0% by weight NO3.

25. The method of claim 24, further comprising; f) milling the pigment particles with organic compound.

26. The method of claim 15, further comprising; e) adding the pigment particles to a process for manufacturing decorative laminating paper.

27. The method of claim 13, further comprising; d) adding the pigment particles to a process for manufacturing decorative laminating paper.

28. The method of claim 27, further comprising; e) laminating the decorative laminating paper.

29. The method of claim 15, further comprising; f) milling the pigment particles with organic compound.