GLASS SHEET COMPRISING AN ENAMELED ZONE AND AN UNDERLAYER

Abstract

A material includes a glass sheet, one face of which includes an enameled zone coated with an opaque enamel layer and a nonenameled zone, an underlayer which is not an enamel layer being positioned solely in at least a part of the enameled zone, under the enamel layer and in contact therewith.

Claims

1. A material comprising a glass sheet, one face of which comprises an enameled zone coated with an opaque enamel layer and a nonenameled zone, an underlayer which is not an enamel layer being positioned solely in at least a part of the enameled zone, under said enamel layer and in contact therewith.

2. The material as claimed in claim 1, wherein the enameled zone represents between 2% and 25% of a surface area of the coated face.

3. The material as claimed in claim 1, wherein the nonenameled zone is uncoated.

4. The material as claimed in claim 1, wherein the underlayer is in contact with the glass sheet.

5. The material as claimed in claim 1, wherein the underlayer is positioned in a part only of the enameled zone.

6. The material as claimed in claim 1, wherein the underlayer is positioned in the whole of the enameled zone.

7. The material as claimed in claim 1, wherein the underlayer is based on an oxide, a nitride or an oxynitride.

8. The material as claimed in claim 1, wherein the underlayer is devoid of coloration.

9. The material as claimed in claim 1, wherein the underlayer is a single layer.

10. The material as claimed in claim 1, wherein the underlayer is a sol-gel layer.

11. The material as claimed in claim 10, wherein the sol-gel layer is based on, or is constituted of, silicon oxide.

12. The material as claimed in claim 1, wherein the thickness of the underlayer is between 10 nm and 1 μm.

13. A process for obtaining a material as claimed in claim 1, comprising depositing an underlayer on a part of a face of a glass sheet and then depositing an opaque enamel layer in at least the zone coated with the underlayer.

14. The process as claimed in claim 13, wherein the deposition of the underlayer is carried out by a sol-gel process, by cathode sputtering or by chemical vapor deposition.

15. A glazing, comprising a material as claimed in claim 1.

16. The material as claimed in claim 2 wherein the enameled zone is provided in the form of a peripheral strip.

17. The material as claimed in claim 7, wherein the underlayer is based on silicon oxide.

18. The glazing as claimed in claim 15, wherein the glazing is a back window, a roof or a windshield of a motor vehicle.

Description

EXAMPLE 1

[0047] In this example, a silica underlayer with a thickness of 70 nm was deposited by cathode sputtering on a sheet of clear soda-lime-silica glass with a thickness of 3.85 mm sold by the applicant company under the Planiclear reference. A layer of black enamel (Ferro 14501) with a wet thickness of 25 μm was subsequently deposited by screen printing on the underlayer. The glass sheet thus coated was subsequently tempered after heat treatment at 650° C. for 180 seconds.

[0048] In a comparative example C1, the enamel was deposited directly in contact with the glass.

[0049] Thirty samples having a size of 70*70 mm.sup.2 were subsequently subjected to three-point bending tests.

[0050] FIG. 1 represents the results of the tests in the form of a graph indicating the probability of failure (denoted P) as a function of the stress (denoted S) in MPa. The results show that the presence of the underlayer makes it possible to improve the mechanical strength of the enameled glass.

EXAMPLE 2

[0051] This example differs from example 1 in that the nature of the underlayer was a sol-gel silica layer.

[0052] The deposition of the underlayer was carried out by centrifugation (spin coating) under the following conditions: 3 ml of sol and speed of 1000 revolutions per minute. The underlayer was subsequently dried at 180° C. for 10 minutes before the enamel deposition. The starting sol comprised 18 g of methyltriethoxysilane, 15 g of isopropanol and 5 g of water acidified to pH 2. The sol was diluted to 66% in water at pH 2 after hydrolysis at ambient temperature.

[0053] In comparative example C2, the enamel was deposited directly on the glass.

[0054] FIG. 2 represents the results of the tests in the form of a graph indicating the probability of failure (denoted P) as a function of the stress (denoted S) in MPa.

[0055] The results show that the presence of the underlayer makes it possible to improve the mechanical strength of the enameled glass.