MIRROR HAVING AN IMPROVED DURABILITY

Abstract

A mirror includes a transparent substrate, a metallic reflecting layer and a protective layer on the back of the mirror, in which at least one barrier layer to corrosive agents with a thickness after drying of less than 1 μm is located between the metallic reflecting layer and the protective layer, the barrier layer being a layer based on metal alkoxides, oxides, phosphates or sulfides and on organic resin, the alkoxides, oxides, phosphates or sulfides being chosen from titanium or zirconium alkoxides or oxides, tin or zinc oxides, zinc, manganese or tin phosphates and zinc sulfide, alone or as a mixture.

Claims

1. A mirror comprising a transparent substrate, a metallic reflecting layer and a protective layer on a back of the mirror, wherein at least one barrier layer to corrosive agents with a thickness after drying of less than 1 μm is located between the metallic reflecting layer and the protective layer, said barrier layer being a layer based on metal alkoxides, oxides, phosphates or sulfides and on organic resin, said alkoxides, oxides, phosphates or sulfides being chosen from titanium or zirconium alkoxides or oxides, tin or zinc oxides, zinc, manganese or tin phosphates and zinc sulfide, alone or as a mixture.

2. The mirror as claimed in claim 1, wherein the barrier layer is obtained from a liquid composition based on an organic resin and on titanium, zirconium or manganese alkoxides, oxides and/or phosphates, alone or as a mixture, in an aqueous or organic solvent.

3. The mirror as claimed in claim 2, wherein the liquid composition is a solution comprising an organic resin and titanium alkoxides, oxides or phosphates.

4. The mirror as claimed in claim 2, wherein the liquid composition comprises between 0.1 and 20 mg/m2 of titanium.

5. The mirror as claimed in claim 1, wherein the organic resin is chosen from acrylic, vinyl, polyurethane, polyester, epoxy, alkyd or styrene resins.

6. The mirror as claimed in claim 1, wherein the thickness of the barrier layer after drying is less than 100 nm.

7. The mirror as claimed in claim 1, further comprising a passivation layer based on a stannous chloride solution on the metallic reflecting layer.

8. The mirror as claimed in claim 1, further comprising a adhesion primer layer placed between the metallic reflecting layer and the barrier layer or between the barrier layer and the protective layer.

9. The mirror as claimed in claim 1, wherein the protective layer is a layer of paint having a thickness of less than 50 μm.

10. The mirror as claimed in claim 1, wherein the protective paint layer is based on a paint comprising less than 130 g/l of organic solvents.

11. A process for the manufacture of a mirror as claimed in claim 1, comprising optionally performing a stage of sensitization of a surface of the substrate, optionally performing a stage of activation of the surface of the substrate to be coated and performing a stage of deposition of the metallic reflecting layer, the method further comprising performing a stage of deposition and of drying of at least one barrier layer and a stage of deposition and drying of a protective layer deposited on the barrier layer.

12. The process as claimed in claim 11, further comprising performing a stage of deposition of a adhesion primer layer after the stage of deposition of the metallic reflecting layer and before the stage of deposition of the barrier layer.

13. The process as claimed in claim 11, wherein the deposition of the barrier layer is carried out by liquid route, by magnetic-field-assisted cathode sputtering, by thermal evaporation, by CVD or PECVD, by pyrolysis, or by chemical route.

14. The process as claimed in claim 12, wherein the deposition of the barrier layer is carried out by liquid route by spraying, with a roller, by dipping, by curtain coating or by sprinkling drying.

15. The process as claimed in claim 11, wherein the drying of the barrier layer is carried out under air or by IR curing.

16. The mirror as claimed in claim 5, wherein the organic resin is a polyvinyl alcohol resin,

17. The mirror as claimed in claim 16, wherein the organic resin is polyvinylphenol.

18. The mirror as claimed in claim 6, wherein the thickness of the barrier layer after drying is less than 40 nm.

19. The mirror as claimed in claim 9, wherein the protective layer is a layer of paint having a thickness of less than 25 μm.

20. The process as claimed in claim 13, wherein the deposition of the barrier layer is carried out by wet route.

21. The process as claimed in claim 20, wherein the deposition of the barrier layer is carried out by sol-gel route.

Description

COMPARATIVE EXAMPLE

[0042] A mirror was prepared as described above by using, as barrier layer, a liquid composition which is an aqueous solution of titanates, without organic resin (Bonderite M-NT 30002), diluted to 10% in demineralized water. After application of a thin film of Bonderite deposited by liquid route on the passivation layer, the layer is dried under air at a temperature of approximately 70° C. The layer thus obtained has a titanium content of 5 mg/m.sup.2. A layer of paint of water-based type (Fenzi) with a thickness of 40 μm is subsequently applied to the barrier layer by the curtain technique.

[0043] Measurements of adhesion of layers were carried out on this sample and the value obtained was 3, reflecting a poor adhesion of the layers to the substrate, not compatible with the standards enforced in the field of mirrors.

[0044] These results clearly show the advantage of the barrier layers based on organic resin and on solution of titanates for improving both the adhesion of the layers and the resistance to sulphide corrosion.