LOW-MAINTENANCE COATING TECHNOLOGY

• US 20090075067A1
• Filed: 09/12/2008
• Published: 03/19/2009
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Cardinal CG Company (Cardinal Glass Industries Incorporated)
• Original Assignee: Cardinal CG Company (Cardinal Glass Industries Incorporated)
• Inventors: GERMAN, John, MYLI, Kari B., HARTIG, Klaus, KRISKO, Annette J.
• Granted Patent: US 7,820,296 B2
• Time in Patent Office: Days
• US Class Current: 428/333
• CPC Class Codes: C03C 17/002 for flat glass, e.g. float glass
• CPC Class Codes: C03C 17/2456 Coating containing TiO2
• CPC Class Codes: C03C 17/3411 with at least two coatings of inorganic materials C03C17/36, C03C17/42 take precedence
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/219 CrOx, MoOx, WOx
• CPC Class Codes: C03C 2217/23 Mixtures
• 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: C23C 14/024 Deposition of sublayers, e.g. to promote adhesion of the coating C23C14/027 takes precedence
• 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
• CPC Class Codes: C23C 14/352 using more than one target C23C14/56 takes precedence
• CPC Class Codes: Y10T 428/261 In terms of molecular thickness or light wave length
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

The invention provides a substrate bearing a low-maintenance coating. In some embodiments, the coating includes a low-maintenance film that includes a thickness of film comprising titania, wherein only part of that thickness includes tungsten. The thickness includes an inner portion and an outer portion, the outer portion being the part that includes tungsten. The invention also provides methods and equipment for depositing such coatings.

Claims

1. A sputtering technique for depositing a low-maintenance coating over a major surface of a substrate, wherein the sputtering technique includes depositing a thickness of film comprising titania, wherein at least part of that thickness includes tungsten oxide and is deposited by sputtering one or more targets having a sputterable material comprising both titania and tungsten oxide, wherein the sputterable material includes:

i) tungsten in oxide form, ii) TiO, and iii) TiO₂.

2. The sputtering technique of claim 1 wherein substantially all the tungsten in the sputterable material is in oxide form.

3. The sputtering technique of claim 1 wherein the depositing is accomplished by sputtering the targets in an atmosphere comprising oxygen.

4. The sputtering technique of claim 1 wherein the sputterable material is characterized by a metal-only atomic ratio of between about 0.01 and about 0.34, this ratio being the number of tungsten atoms in the sputterable material divided by the number of titanium atoms in the sputterable material.

5. The sputtering technique of claim 1 wherein the thickness of film comprising titania includes an inner portion and an outer portion, the inner portion being closer to the substrate than is the outer portion, wherein only the outer portion includes tungsten oxide, the outer portion being deposited as a substantially homogenous film comprising titanium oxide and tungsten oxide.

6. The sputtering technique of claim 5 wherein the inner portion is deposited as film consisting essentially of titania.

7. The sputtering technique of claim 1 wherein the thickness of the film comprising titania is less than 250 Å

.

8. A sputtering target having a sputterable material comprising both titania and tungsten oxide, wherein the sputterable material includes:

i) tungsten in oxide form, ii) TiO, and iii) TiO₂.

9. The sputtering target of claim 8 wherein substantially all the tungsten in the sputterable material is in oxide form.

10. The sputtering target of claim 8 wherein the sputterable material is characterized by a metal-only atomic ratio between about 0.01 and about 0.34, this ratio being the number of tungsten atoms in the sputterable material divided by the number of titanium atoms in the sputterable material.

11. The sputtering target of claim 8 wherein the sputterable material consists essentially of:

i) tungsten in oxide form, ii) TiO, and iii) TiO₂.

12. The sputtering target of claim 8 wherein the target is a cylindrical rotary target, the sputterable material being carried on an exterior wall of an elongated backing tube, the elongated backing tube having a length of at least 24 inches, the target being adapted to rotate about a central axis to which the exterior wall of the backing tube is substantially parallel.

13. A substrate having a major surface on which there is a low-maintenance coating, the low-maintenance coating including a thickness of film comprising titania, said thickness being less than 250 Å

, wherein only part of that thickness includes tungsten oxide, said thickness including an inner portion and an outer portion, the inner portion being closer to the substrate than is the outer portion, the outer portion being the part that includes tungsten oxide.

14. The substrate of claim 13 wherein the thickness of the outer portion is no more than about 90 Å

.

15. The substrate of claim 13 wherein said thickness of film comprising titania is less than about 150 Å

.

16. The substrate of claim 13 wherein the outer portion defines an exposed, outermost face of the low-maintenance coating, the outer portion being a substantially homogenous film comprising both titanium dioxide and tungsten oxide.

17. The substrate of claim 16 wherein the inner portion is a substantially homogenous film consisting essentially of titania.

18. The substrate of claim 13 wherein the outer portion has a tungsten load characterized by a metal-only atomic ratio of between about 0.01 and about 0.34, this ratio being the number of tungsten atoms in the outer portion divided by the number of titanium atoms in the outer portion.

19. The substrate of claim 13 wherein the low-maintenance coating includes a base film between the major surface of the substrate and said thickness of film comprising titania.

20. The substrate of claim 19 wherein the base film and said thickness of film comprising titania have a combined thickness of less than about 150 Å

.

21. The substrate of claim 19 wherein the base film comprises silica.

22. The substrate of claim 19 wherein the base film comprises alumina.

23. The substrate of claim 19 wherein the base film has a thickness of less than about 100 Å

.

24. The substrate of claim 13 wherein a base film is provided between said thickness of film comprising titania and the major surface of the substrate, and an intermediate film is provided between the base film and said thickness of film comprising titania.

25. The substrate of claim 24 wherein the base film and the intermediate film each have a thickness of less than 100 Å

.

26. The substrate of claim 25 wherein base film comprises alumina and the intermediate film comprises silica.

27. The substrate of claim 26 wherein the base film comprises alumina at a thickness of less than about 50 Å

and the intermediate film comprises silica at thickness of less than about 50 Å

.

28. The substrate of claim 13 wherein a transparent conductive oxide film is provided between the major surface of the substrate and the low-maintenance coating.

29. The substrate of claim 28 wherein the substrate is a transparent pane that is part of a multiple-pane insulating glazing unit having a between-pane space, wherein the major surface bearing the low-maintenance coating faces away from the between-pane space of the unit.

30. The substrate of claim 13 wherein the substrate is part of a triple-pane insulating glazing unit.

31. The substrate of claim 13 wherein the substrate is part of a multiple-pane insulating glazing unit having two exterior major surfaces each bearing a low-maintenance coating comprising titania.

32. A substrate having a major surface on which the following films are coated in sequence, moving outwardly from the major surface:

i) a functional film comprising a material selected from the group consisting of indium tin oxide and fluorine-containing tin oxide; and

ii) a thickness of film comprising titania, wherein only part of that thickness includes tungsten oxide, said thickness including an inner portion and an outer portion, the inner portion being closer to the substrate than is the outer portion, the outer portion being the part that includes tungsten oxide,

wherein a thickness ratio defined as said thickness of film comprising titania divided by the thickness of the functional film is between about 0.004 and about 0.08.

33. The substrate of claim 32 wherein said thickness ratio is between about 0.004 and about 0.025.

34. The substrate of claim 32 wherein between the functional film and said thickness of film comprising titania there is a layer having a thickness of less than 100 Å

.

35. The substrate of claim 32 wherein between the functional film and said thickness of film comprising titania there is a layer comprising silica, alumina, or both.

36. The substrate of claim 32 wherein between the functional film and said thickness of film comprising titania there are two layers of film having a combined thickness of less than 100 Å

.

37. A substrate having a major surface on which there is both a transparent conductive oxide film and a low-maintenance coating, the transparent conductive oxide film being closer to the substrate than is the low-maintenance coating, the low-maintenance coating including a thickness of film comprising titania, wherein only part of that thickness includes tungsten oxide, said thickness including an inner portion and an outer portion, the inner portion being closer to the substrate than is the outer portion, the outer portion being the part that includes tungsten oxide, wherein between the transparent conductive oxide film and said thickness of film comprising titania there are two layers including one comprising silica and one comprising alumina.

38. The substrate of claim 37 wherein said two layers have a combined thickness of less than 100 angstroms.

39. The substrate of claim 37 wherein said layer comprising alumina is closer to the substrate than is said layer comprising silica.

40. The substrate of claim 37 wherein said layer comprising alumina is contiguous to said layer comprising silica.

41. The substrate of claim 37 wherein the substrate is a transparent pane that is part of a multiple-pane insulating glazing unit having a between-pane space, wherein the major surface bearing the transparent conductive oxide film and the low-maintenance coating faces away from the between-pane space of the unit.

42. A method of producing a low-maintenance product, the method comprising using a coater to deposit a low-maintenance coating on a major surface of a substrate, the low-maintenance coating including a thickness of film comprising titania, wherein only part of that thickness includes tungsten oxide, wherein the thickness of film comprising titania includes an inner portion and an outer portion, the outer portion being the part that includes tungsten oxide, the inner portion being deposited before the outer portion is deposited, wherein heating is performed while the substrate is inside the coater.

43. The method of claim 42 wherein said heating brings the substrate to a maximum temperature of greater than 140°

F. but less than 350°

F.

44. The method of claim 42 wherein the substrate is subjected to said heating after the inner portion has been deposited but before the outer portion is deposited.

45. The method of claim 42 wherein said heating is performed inside a deposition chamber adapted for depositing at least part of the inner portion or at least part of the outer portion.

46. The method of claim 42 wherein the low-maintenance coating is deposited in a sputter coater.

47. The method of claim 44 wherein said heating is performed inside a heating chamber positioned between a first deposition chamber and a second deposition chamber, the first deposition chamber being adapted for depositing the inner portion, the second deposition chamber being adapted for depositing the outer portion.

48. The method of claim 44 wherein the method includes conveying the substrate through one or more inter-stage sections that are part of said coater, said inter-stage sections being adapted for maintaining the substrate at a temperature of at least about 160°

F.

49. The method of claim 48 wherein at least one of said inter-stage sections is positioned between a first deposition chamber and a second deposition chamber, the first deposition chamber being adapted for depositing the inner portion, the second deposition chamber being adapted for depositing the outer portion.

50. The method of claim 44 wherein the substrate is also subjected to heating before the inner portion has been deposited.

51. The method of claim 44 wherein the substrate is also subjected to heating during deposition of either or both of the inner portion and outer portion.

52. A method of producing a low-maintenance product, the method comprising providing a substrate having a major surface on which there is a low-maintenance coating, the low-maintenance coating including a thickness of film comprising titania, said thickness being greater than about 50 Å

but less than 250 Å

, wherein only part of that thickness includes tungsten oxide, said thickness including an inner portion and an outer portion, the inner portion being closer to the substrate than is the outer portion, the outer portion being the part that includes tungsten oxide, the method further comprising heat treating said coated substrate to bring said coated substrate to a temperature of at least about 160°

F.

53. The method of claim 52 wherein the heat treating is accomplished by positioning said coated substrate in a heating chamber for at least 60 seconds during which time the heating chamber is maintained at a temperature of at least 650°

C.

54. The method of claim 52 further comprising cooling said coated substrate back down to room temperature, at which point said coated substrate exhibits a haze of less than about 0.4.

55. A sputter coater, comprising:

a chamber selected from the group consisting of a sputtering chamber and a heating chamber;

at least one inter-stage section extending from said chamber, the inter-stage section having an interior space surrounded by alternating layers of a conductive metal and a ceramic material;

at least one heating source adapted to apply heat to the inter-stage section, so that the interior space is adapted for being maintained at a temperature of at least about 160°

F.

56. The sputter coater of claim 55 wherein the inter-stage section connects two sputtering chambers.

57. The sputter coater of claim 55 wherein the coater is adapted for depositing a thickness of film comprising titania, wherein only a part of that thickness includes tungsten oxide, said thickness including an inner portion and an outer portion, the inner portion being closer to the substrate than is the outer portion, the outer portion being the part that includes tungsten oxide.

58. The sputter coater of claim 57 wherein said inter-stage section connects a first sputtering chamber that is adapted for depositing the inner portion and a second sputtering chamber that is adapted for depositing the outer portion.