Substrate, in particular glass substrate, supporting at least one stack of a photocatalytic layer and a sublayer for the heteroepitaxial growth of said layer

• US 20070129248A1
• Filed: 10/22/2004
• Published: 06/07/2007
• Est. Priority Date: 10/23/2003
• Status: Active Grant

• Current Assignee: Saint-Gobain Glass France (Compagnie De Saint-Gobain)
• Original Assignee: Saint-Gobain Glass France (Compagnie De Saint-Gobain)
• Inventors: Nadaud, Nicolas, Labrousse, Laurent
• Granted Patent: US 7,737,080 B2
• Time in Patent Office: Days
• US Class Current: 502/350
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 17/3435 comprising a nitride, oxynitride, boronitride or carbonitride
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• CPC Class Codes: C03C 25/52 Coatings containing inorganic materials only

Abstract

The invention relates to a structure, comprising a substrate supporting a layer with a photocatalytic and anti-soiling property on at least part of the surface thereof, said layer being based on titanium dioxide (TiO₂) which is at least partially crystallized in the anatase form thereof. Said structure is characterised in comprising a sublayer (SC) directly under at least one TiO₂ layer, said sublayer having a crystallographic structure which provides assistance to crystallization by heteroepitaxial growth in the anatase form of the TiO₂-based upper layer, the photocatalytic property being obtained without any heating step.

Claims

1. A structure comprising a substrate bearing, on at least part of its surface, an antisoiling layer having a photocatalytic property, based on titanium dioxide (TiO₂) at least partly crystallized in its anatase form, wherein it includes, immediately beneath at least one TiO₂ layer, an underlayer (UL) having a crystallographic structure that has assisted in the crystallization, by heteroepitaxial growth in the anatase form, of the TiO₂-based upper layer, the photocatalytic property having been acquired without any heating step.

2. The structure as claimed in claim 1, wherein the underlayer (UL) is based on a compound crystallized in a cubic or tetragonal system and having a lattice cell dimension equal to that of TiO₂ crystallized in anatase form to within ±

8%.

3. The structure as claimed in claim 1, wherein the underlayer (UL) consists of ATiO₃, A denoting barium or strontium.

4. The structure as claimed in claim 1, wherein the underlayer (UL) has a thickness of between 10 and 100 nm.

5. The structure as claimed in claim 1, wherein the substrate consists of a sheet, whether plane or with curved faces, of monolithic or laminated glass, glass-ceramic or a hard thermoplastic, or else consists of glass or glass-ceramic fibers, said sheets or said fibers having, where appropriate, received at least one other functional layer before application of the underlayer (UL).

6. The structure as claimed in claim 5, wherein the substrate is made of glass or glass-ceramic, wherein at least one functional layer subjacent to the underlayer (UL) is a layer forming a barrier to the migration of alkali metals from the glass or glass-ceramic.

7. The structure as claimed in claim 5, wherein at least one functional layer subjacent to the underlayer (UL) is a layer having an optical functionality, a thermal control layer or a conducting layer.

8. The structure as claimed in claim 5, wherein the substrate is made of glass or glass-ceramic, wherein the substrate has received a layer acting as a barrier to the migration of alkali metals from the glass or glass-ceramic, followed by a monolayer, bilayer or trilayer having an optical functionality.

9. The structure as claimed in claim 1, wherein the TiO₂ base layer consists of TiO₂ alone or of TiO₂ doped with at least one dopant selected from the group consisting of N;

pentavalent cations;

Fe; and

Zr.

10. The structure as claimed in claim 1, wherein the TiO₂ layer has been deposited at room temperature by vacuum sputtering, where appropriate magnetron and/or ion-beam sputtering.

11. The structure as claimed in claim 1, wherein the underlayer (UL) has been deposited at room temperature by vacuum sputtering, where appropriate magnetron and/or ion-beam sputtering.

12. The structure as claimed in claim 3, wherein ATiO₃ has been deposited at room temperature by vacuum sputtering, where appropriate magnetron and/or ion-beam sputtering, using ceramic targets selected from the group consisting of ATiO₃, ATiO_3-x, wherein 0<

x≦

3, and ATi,

the supply being a radiofrequency supply and the atmosphere in the sputtering chamber containing only argon when ATiO₃ is used as target, the supply being a DC or AC supply and the reactive atmosphere in the sputtering chamber containing oxygen and argon when ATi or ATiO_3-x is used as target,

the TiO₂ layer having been deposited in a following step in the same sputtering chamber.

13. The structure as claimed in claim 1, wherein the TiO₂ layer is coated with at least one overlayer of a material that does not disturb the antisoiling function of the TiO₂ layer.

15. A process for producing a structure as defined in claim 1, wherein an ATiO₃ underlayer, A denoting barium or strontium, is deposited on a substrate made of glass or glass-ceramic or hard polycarbonate-type plastic, of the sheet type, or on glass or glass-ceramic fibers, followed by an optionally doped TiO₂ layer, at least one overlayer of a material not disturbing the antisoiling function of the TiO₂ layer then possibly being deposited where appropriate on this TiO₂ layer.

16. The process as claimed in claim 15, wherein the ATiO₃ underlayer (UL) and the TiO₂ layer are deposited in succession at room temperature by vacuum sputtering, where appropriate magnetron and/or ion-beam sputtering, in the same chamber, the targets used for depositing said underlayer selected from the group consisting of ATiO₃, ATiO_3-x, wherein 0<

x≦

3, and ATi, the supply being a radiofrequency supply and the atmosphere in the sputtering chamber containing only argon when ATiO₃ is used as target, the supply being a DC or AC supply and the reactive atmosphere in the sputtering chamber containing oxygen and argon when ATi or ATiO_3-x is used as target; and

the target used for depositing the TiO₂ being Ti or TiO_x, where 0<

x<

2.

17. The process as claimed in claim 16, wherein no heat treatment step is carried out after the TiO₂ layer and, where appropriate, the overlayer(s) have been deposited.

18. The process as claimed in claim 15, wherein the coating of a glass or glass-ceramic substrate is carried out, wherein, before the underlayer (UL) has been applied, at least one layer forming a barrier to the migration of alkali metals present in the glass or glass-ceramic is deposited on the substrate, an annealing or toughening operation then possibly being carried out, after the TiO₂ layer and, where appropriate, the overlayer(s) have been deposited, at a temperature of between 250°

C. and 550°

C. in the annealing operation, and at a temperature of at least 600°

C. in the case of the toughening operation.

19. The process as claimed in claim 15, wherein before the ATiO₃ underlayer (UL) has been applied, at least one functional layer selected from the group consisting of layers having an optical functionality, thermal control layers and conducting layers is deposited, said functional layers being advantageously deposited by vacuum sputtering, where appropriate magnetron and/or ion-beam sputtering.

20. A single or multiple glazing comprising, respectively, one or more than one structure as defined in claim 1, both the TiO₂-based antisoiling layer and its associated underlayer (UL) being present on at least one of its external faces, the faces not having the TiO₂-based antisoiling layer and its associated underlayer possibly including at least one other functional layer.

14. The application of ATiO₃ to the formation of a layer for assisting in the crystallization, in the anatase form by heteroepitaxial growth, of an optionally doped ATiO₂-based upper layer, A denoting barium or strontium.