Graded photocatalytic coatings

• US 7,294,404 B2
• Filed: 12/22/2004
• Issued: 11/13/2007
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Cardinal CG Company (Cardinal Glass Industries Incorporated)
• Original Assignee: Cardinal CG Company (Cardinal Glass Industries Incorporated)
• Inventors: Hartig, Klaus, Krisko, Annette J.
• Primary Examiner(s): Blackwell; G.
• Application Number:
  US11/021,482
• Publication Number:
  US 20050137084A1
• Time in Patent Office: 1,056 Days
• Field of Search: 428/428, 428/432, 428/698, 428/699, 428/701
• US Class Current: 428/428
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• CPC Class Codes: C03C 2217/91 Coatings containing at least one layer having a composition gradient through its thickness
• CPC Class Codes: C03C 2218/154 by sputtering
• CPC Class Codes: C03C 2218/365 Coating different sides of a glass substrate
• CPC Class Codes: C23C 14/0084 Producing gradient compositions
• CPC Class Codes: C23C 14/024 Deposition of sublayers, e.g. to promote adhesion of the coating C23C14/027 takes precedence
• CPC Class Codes: C23C 14/027 Graded interfaces
• CPC Class Codes: C23C 14/083 of refractory metals or yttrium
• CPC Class Codes: C23C 14/3464 using more than one target C23C14/56 takes precedence

Abstract

The invention provides graded photocatalytic coatings. In one aspect, the invention provides a substrate carrying a photocatalytic coating that includes a first graded film region and a second graded film region. The first graded film region has a substantially continuously decreasing concentration of a first transparent dielectric material and a substantially continuously increasing concentration of a second transparent dielectric material. The second graded film region has a substantially continuously decreasing concentration of the second transparent dielectric material and a substantially continuously increasing concentration of a third transparent dielectric material. In certain embodiments, the first transparent dielectric material comprises silicon dioxide, the second transparent dielectric material comprises zirconium oxide, and the third transparent dielectric material comprises titanium oxide. The invention also provides methods and equipment for depositing graded photocatalytic coatings.

Claims

1. A substrate bearing a photocatalytic coating comprising, in sequence outwardly:

a) a first graded film region having a substantially continuously decreasing concentration of a first transparent dielectric material and a substantially continuously increasing concentration of a second transparent dielectric material;

b) a second graded film region having a substantially continuously decreasing concentration of the second transparent dielectric material and a substantially continuously increasing concentration of a third transparent dielectric material, the third transparent dielectric material comprising a photocatalyst; and

wherein the coating consists essentially of film regions of different transparent dielectric materials interlocked by continuous transition, and the coating does not include any discrete film interfaces, the coating comprising a homogenous intermediate film region that is bounded by and gradually transitions into the first and second graded film regions, the homogenous intermediate film region having a thickness and comprising said second transparent dielectric material, the homogenous intermediate film region having a composition that is substantially uniform across its thickness.

2. The substrate of claim 1 wherein the photocatalytic coating has a total optical thickness of less than about 920 Å

.

3. The substrate of claim 1 wherein the photocatalytic coating has an average surface roughness of about 2 nm or less.

4. The substrate of claim 1 wherein the thickness of the homogenous intermediate film region is between about 40 Å

and about 160 Å

.

5. The substrate of claim 1 wherein the coating has a total thickness of less than about 300 angstroms.

6. The substrate of claim 1 wherein the coating has a total thickness of less than about 150 angstroms.

7. The substrate of claim 1 wherein the substrate has an exterior photocatalytic film-side visible reflectance of less than about 15%.

8. The substrate of claim 7 wherein the exterior photocatalytic film-side visible reflectance is less than about 13%.

9. The substrate of claim 1 wherein the photocatalytic coating comprises a homogenous inner film region between the substrate and the first graded film region, the homogenous inner film region comprising said first transparent dielectric material.

10. The substrate of claim 9 wherein the homogenous inner film region has a thickness of between about 40 Å

and about 200 Å

.

11. The substrate of claim 9 wherein said first transparent dielectric material is silicon dioxide, such that the homogenous inner film region comprises silicon dioxide.

12. The substrate of claim 11 wherein the homogenous inner film region consists essentially of silicon dioxide.

13. The substrate of claim 1 wherein said second transparent dielectric material is zirconium oxide, such that the homogenous intermediate film region comprises zirconium oxide.

14. The substrate of claim 13 wherein the homogenous intermediate film region consists essentially of zirconium oxide.

15. The substrate of claim 1 wherein the photocatalytic coating comprises a homogenous outer film region further from the substrate than the second graded film region, the homogenous outer film region comprising said third transparent dielectric material.

16. The substrate of claim 15 wherein the homogenous outer film region has a thickness of between about 40 Å

and about 160 Å

.

17. The substrate of claim 15 wherein said third transparent dielectric material is titanium oxide, such that the homogenous outer film region comprises titanium oxide.

18. The substrate of claim 17 wherein the homogenous outer film region consists essentially of titanium oxide.

19. A substrate bearing a photocatalytic coating comprising, in sequence outwardly:

a) a first graded film region having a substantially continuously decreasing concentration of silicon dioxide and a substantially continuously increasing concentration of zirconium oxide;

b) a second graded film region having a substantially continuously decreasing concentration of zirconium oxide and a substantially continuously increasing concentration of titanium oxide; and

wherein the coating consists essentially of film regions of different transparent dielectric materials interlocked by continuous transition, and the coating does not include any discrete film interfaces, each graded film region extending between two homogenous film regions of different composition, each graded film region having a thickness of greater than about 10 angstroms but less than about 75 angstroms.

20. The substrate of claim 19 wherein the photocatalytic coating comprises a homogenous inner film region between the substrate and the first graded film region, the homogenous inner film region consisting essentially of silicon dioxide, a homogenous intermediate film region between the first graded film region and the second graded film region, the homogenous intermediate film region consisting essentially of zirconium oxide, and a homogenous outer film region further from the substrate than the second graded film region, the homogenous outer film region consisting essentially of titanium oxide.

21. The substrate of claim 20 wherein the homogenous inner film region has a thickness of between about 40 Å

and about 200 Å

, the homogenous intermediate film region has a thickness of between about 40 Å and

about 160 Å

, and the homogenous outer film region has a thickness of between about 40 Å and

about 160 Å

.

22. The substrate of claim 19 wherein the coating has a total thickness of less than about 300 angstroms.

23. The substrate of claim 19 wherein the coating has a total thickness of less than about 150 angstroms.

25. The substrate of claim 23 wherein the graded photocatalytic coating is a sputtered coating.

24. A substrate bearing a graded photocatalytic coating, the graded photocatalytic coating comprising at least one graded film region having a composition that transitions, with increasing distance from the substrate, from one transparent dielectric material to another, the graded photocatalytic coating having an exterior photocatalytic film-side visible reflectance of less than about 13%;

wherein the coating consists essentially of film regions of different transparent dielectric materials interlocked by continuous transitions, the coating has a total thickness of less than about 150 angstroms, and the graded film region has a thickness of greater than about 10 angstroms but less than about 75 angstroms.

26. The substrate of claim 24 wherein the graded film region has a thickness of greater than about 10 angstroms but less than about 50 angstroms.

27. The substrate of claim 24 wherein the substrate is part of an IG unit provided with two coatings:

the graded photocatalytic coating and a low-emissivity coating, the two coatings being on opposite sides of the substrate, the low-emissivity coating having less than 200 angstroms of transparent dielectric film between the substrate and a silver-containing film of the low-emissivity coating.

28. The substrate of claim 27 wherein the low-emissivity coating has less than 160 angstroms of transparent dielectric film between the substrate and said silver-containing film.

29. A substrate bearing a graded photocatalytic coating, the coating being deposited over a major surface of the substrate and comprising at least one graded film region having a composition that transitions, with increasing distance from the substrate, from one transparent dielectric material to another, wherein at least one of these transparent dielectric materials comprises titania, the graded film region having a thickness of greater than about 10 angstroms but less than about 75 angstroms;

wherein the coating consists essentially of film regions of different transparent dielectric materials interlocked by continuous transition.

30. The substrate of claim 29 wherein the graded film region is deposited at a thickness of greater than about 10 angstroms but less than about 50 angstroms.

31. The substrate of claim 29 wherein the graded film region is deposited at a thickness of greater than about 10 angstroms but less than about 40 angstroms.

32. The substrate of claim 29 wherein the graded photocatalytic coating is a sputtered coating.

33. The substrate of claim 29 wherein the coating has a total thickness of less than about 300 angstroms.

34. The substrate of claim 29 wherein the coating has a total thickness of less than about 150 angstroms.

35. The substrate of claim 29 wherein the substrate is part of an IG unit provided with two coatings:

the graded photocatalytic coating and a low-emissivity coating, the two coatings being on opposite sides of the substrate, the low-emissivity coating having less than 200 angstroms of transparent dielectric film between the substrate and a silver-containing film of the low-emissivity coating.

36. The substrate of claim 35 wherein the low-emissivity coating has less than 160 angstroms of transparent dielectric film between the substrate and said silver-containing film.