PHOTOCATALYTIC COATING

• US 20100190633A1
• Filed: 12/17/2007
• Published: 07/29/2010
• Est. Priority Date: 12/22/2006
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Anderson, Mark T., Bai, Feng, Gould, Rachael A.T.
• Application Number:
  US12/519,844
• Publication Number:
  US 20100190633A1
• Time in Patent Office: Days
• US Class Current: 502/63
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0215 Coating
• CPC Class Codes: C04B 14/14 Minerals of vulcanic origin granite C04B14/048
• CPC Class Codes: C04B 14/30 Oxides other than silica ferrites C04B14/363
• CPC Class Codes: C04B 14/305 Titanium oxide, e.g. titanates
• CPC Class Codes: C04B 18/14 from metallurgical processes treatment of molten slag C04B5/00
• CPC Class Codes: C04B 20/1077 Cements, e.g. waterglass
• CPC Class Codes: C04B 2103/54 Pigments; Dyes
• CPC Class Codes: C04B 2111/00586 Roofing materials
• CPC Class Codes: C04B 2111/00827 Photocatalysts; materials containing photocatalysts to avoid staining by air pollutants C04B2111/2061
• CPC Class Codes: C04B 2111/2061 Materials containing photocatalysts, e.g. TiO2, for avoiding staining by air pollutants or the like
• CPC Class Codes: C04B 28/26 Silicates of the alkali metals
• CPC Class Codes: C04B 41/5041 Titanium oxide or titanates
• CPC Class Codes: C04B 41/5089 Silica sols, alkyl, ammonium or alkali metal silicate cements
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: C09D 1/02 alkali metal silicates
• CPC Class Codes: C09D 7/61 inorganic
• CPC Class Codes: C09D 7/67 Particle size smaller than 100 nm
• CPC Class Codes: C09D 7/68 Particle size between 100-1000 nm
• CPC Class Codes: E04D 13/002 Provisions for preventing vegetational growth, e.g. fungi, algae or moss
• CPC Class Codes: E04D 7/005 : characterised by loose or embedded gravel or granules as an outer protection of the roof covering
• CPC Class Codes: Y02W 30/91 : Use of waste materials as fillers for mortars or concrete

Abstract

In one aspect, the present invention is directed to a coating composition. The coating composition comprises a dispersion of photocatalysts having a mean cluster size of less than about 300 nm and an alkali metal silicate binder. In another aspect, the present invention is directed to a coated article. The coated article has a photocatalytic coating with improved transparency on its external surface that is formed from the aforesaid coating composition.

Claims

1. A coated article, comprising:

an article having an external surface and a coating on the external surface of the article, wherein the coating is formed from a composition comprising a dispersion of photocatalysts having a mean cluster size of less than about 300 nm and an alkali metal silicate binder.

2. The coated article of claim 1, wherein the article is a roofing granule.

3. The coated article of claim 1, wherein the article is a tile.

4. The coated article of claim 1, wherein the photocatalysts comprise TiO₂, ZnO, WO₃, SnO₂, CaTiO₃, Fe₂O₃, MoO₃, Nb₂O₅, Ti_xZr_(1-x)O₂, SiC, SrTiO₃, CdS, GaP, InP, GaAs, BaTiO₃, KNbO₃, Ta₂O₅, Bi₂O₃, NiO, Cu₂O, SiO₂, MoS₂, InPb, RuO₂, CeO₂, Ti(OH)₄, or combinations thereof.

5. The coated article of claim 1, wherein the photocatalysts comprise crystalline anatase TiO₂, crystalline rutile TiO₂, crystalline ZnO, or combinations thereof.

6. The coated article of claim 1, wherein the photocatalysts are doped with C, N, S, F, Pt, Pd, Au, Ag, Os, Rh, RuO₂, Nb, Cu, Sn, Ni, Fe, or combinations thereof.

7. The coated article of claim 1, wherein the alkali metal silicate binder comprises lithium silicate, sodium silicate, potassium silicate, or combinations thereof.

8. The coated article of claim 1, wherein the alkali metal silicate binder comprises a pigment.

9. The coated article of claim 1, wherein each of the absolute values of the difference in the L*, a*, b* numbers between the coated article and the base article is less than about 2.

10. A coated roofing granule, comprising:

a roofing granule having an external surface and a coating on the external surface of the roofing granule, wherein the coating is formed from a composition comprising a dispersion of photocatalysts having a mean cluster size of less than about 300 nm and an alkali metal silicate binder, and wherein each of the absolute values of the difference in the L*, a*, b* numbers between the coated granule and the base granule is less than about 2.

11. A coating composition, comprising:

a dispersion of photocatalyts having a mean cluster size of less than about 300 nm and an alkali metal silicate binder.

12. The coating composition of claim 11, wherein the photocatalysts comprise TiO₂, ZnO, WO₃, SnO₂, CaTiO₃, Fe₂O₃, MoO₃, Nb₂O₅, Ti_xZr_(1-x)O₂, SiC, SrTiO₃, CdS, GaP, InP, GaAs, BaTiO₃, KNbO₃, Ta₂O₅, Bi₂O₃, NiO, Cu₂O, SiO₂, MoS₂, InPb, RuO₂, CeO₂, Ti(OH)₄, or combinations thereof.

13. The coating composition of claim 11, wherein the photocatalysts comprise crystalline anatase TiO₂, crystalline rutile TiO₂, crystalline ZnO, or combinations thereof.

14. The coating composition of claim 11, wherein the photocatalysts are doped with C, N, S, F, Pt, Pd, Au, Ag, Os, Rh, RuO₂, Nb, Cu, Sn, Ni, Fe, or combinations thereof.

15. The coating composition of claim 11, wherein the alkali metal silicate binder comprises lithium silicate, sodium silicate, potassium silicate, or combinations thereof.

16. The coating composition of claim 11, wherein the alkali metal silicate binder comprises a pigment.

17. A method of making a coated article, comprising:

providing an article having an external surface, providing a composition comprising a dispersion of photocatalysts having a mean cluster size of less than about 300 nm and an alkali metal silicate binder, depositing the composition onto the article, and heating the deposited article to form a coating thereon.

18. The method of claim 17, wherein the article is a roofing granule.

19. The method of claim 17, wherein the article is a tile.

20. The method of claim 17, wherein the photocatalysts comprise TiO₂, ZnO, WO₃, SnO₂, CaTiO₃, Fe₂O₃, MoO₃, Nb₂O₅, Ti_xZr_(1-x)O₂, SiC, SrTiO₃, CdS, GaP, InP, GaAs, BaTiO₃, KNbO₃, Ta₂O₅, Bi₂O₃, NiO, Cu₂O, SiO₂, MoS₂, InPb, RuO₂, CeO₂, Ti(OH)₄, or combinations thereof.

21. The method of claim 17, wherein the photocatalysts comprise crystalline anatase TiO₂, crystalline rutile TiO₂, crystalline ZnO, or combinations thereof.

22. The method of claim 17, wherein the photocatalysts are doped with C, N, S, F, Pt, Pd, Au, Ag, Os, Rh, RuO₂, Nb, Cu, Sn, Ni, Fe, or combinations thereof.

23. The method of claim 17, wherein the alkali metal silicate binder comprises lithium silicate, sodium silicate, potassium silicate, or combinations thereof.

24. The method of claim 17, wherein the alkali metal silicate binder comprises a pigment.

25. The method of claim 17, wherein each of the absolute values of the difference in the L*, a*, b* numbers between the coated article and the base article is less than about 2.

26. A method of making a coated roofing granule, comprising:

providing a roofing granule having an external surface, providing a composition comprising a dispersion of photocatalysts having a mean cluster size of less than about 300 nm and an alkali metal silicate binder, depositing the composition onto the roofing granule, and heating the deposited roofing granule to form a coating thereon, wherein each of the absolute values of the difference in the L*, a*, b* numbers between the coated granule and the base granule is less than about 2.