GLASS SHEET COATED WITH A STACK OF THIN LAYERS AND AN ENAMEL LAYER

Abstract

A material includes a glass sheet coated on at least part of one of the faces thereof with a stack of thin layers, the stack of thin layers being coated on at least part of the surface thereof with an enamel layer not including bismuth, the enamel layer being coated with a non-stick layer.

Claims

1. A material comprising a glass sheet coated on at least part of one of the faces thereof with a stack of thin layers, said stack of thin layers being coated on at least part of a surface thereof with an enamel layer not comprising bismuth, said enamel layer being coated with a non-stick layer.

2. The material according to claim 1, wherein the stack of thin layers comprises at least one layer based on a nitride.

3. The material according to claim 1, wherein the stack of thin layers comprises at least one functional layer.

4. The material according to claim 16, wherein the at least one electrically conductive functional layer is selected from metal layers and layers of a transparent conductive oxide.

5. The material according to claim 1, wherein the enamel layer is based on zinc borosilicate.

6. The material according to claim 1, wherein the enamel layer is opaque, has a black hue, and forms a strip at the periphery of the glass sheet.

7. The material according to claim 1, wherein the non-stick layer is a layer based on refractory particles.

8. The material according to claim 1, wherein the non-stick layer is a sol-gel layer.

9. A laminated bent glazing, comprising a material according to claim 1, adhesively bonded to an additional glass sheet by a lamination interlayer, such that the enamel layer and the stack of thin layers are facing said lamination interlayer.

10. The laminated bent glazing according to claim 9, wherein the additional glass sheet has a thickness of between 0.5 and 1.2 mm.

11. The laminated bent glazing according to claim 9, wherein the additional glass sheet carries, on the face opposite the face facing the lamination interlayer, an additional stack of thin layers.

12. A method for obtaining a material according to claim 1, comprising: providing a glass sheet coated on at least part of one of faces thereof with a stack of thin layers, then depositing, on at least part of the surface of the stack of thin layers, an enamel layer not comprising bismuth, then depositing, on said enamel layer, a non-stick layer.

13. The method according to claim 12, wherein the depositing of the enamel layer and the depositing of the non-stick layer are carried out by screen printing.

14. A method for obtaining a laminated bent glazing according to claim 9, comprising: providing said material and an additional glass sheet, then simultaneously bending the material and the additional glass sheet, then laminating said material with the additional glass sheet, by a lamination interlayer, such that the enamel layer and the stack of thin layers are facing said interlayer.

15. The material according to claim 2, wherein the at least one layer based on a nitride is a nitride of at least one element selected from aluminum, silicon, zirconium, titanium.

16. The material according to claim 3, wherein the at least one functional layer is an electrically conductive functional layer.

17. The material according to claim 4, wherein the metal layers are silver or niobium layers and the layers of a transparent conductive oxide are selected from indium tin oxide, doped tin oxides, and doped zinc oxides.

18. The material according to claim 7, wherein the refractory particles are pigments.

19. The material according to claim 8, wherein the sol-gel layer is a silica layer.

20. The laminated bent glazing according to claim 9, wherein the enamel layer and the stack of thin layers are on face 2 of the laminated bent glazing.

Description

[0095] The example embodiments which follow illustrate the invention in a non-limiting manner.

[0096] Glass sheets 2.1 mm thick, coated beforehand by cathode sputtering of a stack of thin layers comprising two silver layers protected by zinc oxide layers, silicon nitride layers and NiCr blockers, were coated by screen printing with enamel layers with a wet thickness of 25 μm.

[0097] In the examples according to the invention, the enamel layer “E1” (enamel sold by Ferro under the reference 144011) was based on a zinc borosilicate frit (without bismuth) and black pigments based on oxides of chromium and copper.

[0098] In comparative examples, the enamel layer “E2” (enamel sold by Prince under the reference DV173770/N) was based on a bismuth zinc borosilicate frit and black pigments based on oxides of chromium and copper.

[0099] After drying at a temperature of 150° C., a non-stick layer of the following composition, according to the examples, was then deposited on the enamel layer by screen printing: [0100] A1: pigments of TiO.sub.2, wet thickness approximately 10 μm, having a D50 of the order of 3 to 5 μm and a D90 of the order of 10 μm. [0101] A2: sol-gel silica, wet thickness of approximately 7 μm environ, deposited from a solution sold under the reference TLU0059B01 by Ferro [0102] A3: enamel layer E2, wet thickness 25 μm [0103] A4: mixture of 80% by weight of enamel E1 with 20% by weight of TiO.sub.2 pigments, wet thickness of 10 μm.

[0104] The glass sheet thus coated was then subjected to a pre-firing treatment at 570° C. for 120 seconds.

[0105] An additional glass sheet, made of tinted glass 2.1 mm thick and covered on face 4 with a low-emissivity stack based on ITO, was then placed on the coatings side of the glass sheet. An interlayer powder providing a space of a few tens of micrometers, based on calcium carbonate, was inserted between the two glass sheets. The assembly was then subjected to a bending heat treatment at 600° C. for 480 seconds.

[0106] Table 1 below summarizes the results obtained, giving for each example (comparative examples C1 to C3 and examples 1 to 3 according to the invention) the nature of the enamel layer and of the non-stick layer (when it was present) and also the results in terms of appearance and bonding.

[0107] The appearance, more particularly the black color viewed from face 1, is evaluated by measuring the lightness L* in reflection (illuminant D65, reference observer 10°). The bonding is evaluated qualitatively by visual observation.

TABLE-US-00002 TABLE 1 Example C1 C2 1 2 C3 3 Enamel E2 E1 E1 E1 E1 E1 Non-stick layer — — A1 A2 A3 A4 L* 20 <5 <5 <5 15 <5 Bonding no yes no no no no

[0108] Comparative examples C1 and C2 do not use a non-stick layer. Example C1 shows that bismuth enamels, if they do not lead to bonding, do not make it possible to obtain the desired black hue, due to interactions between the enamel and the stack of thin layers during bending. The enamel without bismuth of comparative example C2 makes it possible to achieve the desired hue, but bonding between the two glass sheets is observed.

[0109] Comparative example C3 uses an enamel without bismuth in contact with the stack, topped with a bismuth enamel in contact with the additional glass sheet. Bonding is then prevented, but the presence of the bismuth enamel, even if it is not in contact with the stack of thin layers, degrades the appearance.

[0110] Examples 1 to 3 according to the invention show that the use of a non-stick layer in combination with an enamel without bismuth makes it possible to obtain both an absence of bonding and a satisfactory appearance.