METHOD FOR OBTAINING A LAMINATED BENT GLAZING

Abstract

A method for obtaining a laminated bent glazing, particularly for a motor vehicle windscreen or roof includes (b) depositing, on a part of the surface of a stack of thin layers deposited on a first glass sheet, in a zone referred to as zone to be demarginated, a washable dissolving layer, a pre-firing at the end of which the stack of thin layers located under the washable dissolving layer is dissolved by the washable dissolving layer, creating a demarginated zone, eliminating (d) the washable dissolving layer by washing, bending (e) the first glass sheet and an additional glass sheet, together or separately, laminating (g) the first glass sheet with an additional glass sheet by a lamination interlayer having an opaque zone arranged facing the demarginated zone.

Claims

1. A method for obtaining a laminated bent glazing, comprising: a. providing a first glass sheet, coated on at least part of one of the faces thereof with a stack of thin layers, b. depositing, on a part of a surface of the stack of thin layers, in a zone to be demarginated, a washable dissolving layer, c. pre-firing the first glass sheet coated with the washable dissolving layer at the end of which the stack of thin layers located under the washable dissolving layer is dissolved by said washable dissolving layer, d. eliminating the washable dissolving layer by washing, creating a demarginated zone, e. bending the first glass sheet and an additional glass sheet, together or separately, f. providing a lamination interlayer comprising an opaque zone, and g. laminating said first glass sheet with the additional glass sheet by the lamination interlayer so that the opaque zone of said lamination interlayer is arranged facing the demarginated zone and the stack of thin layers faces the lamination interlayer.

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

3. The method according to claim 1, wherein the washable dissolving layer is a mineral layer comprising at least one phosphate.

4. The method according to claim 1, wherein the washable dissolving layer is deposited by screen printing.

5. The method according to claim 1, wherein a thickness of the washable dissolving layer is between 5 and 50 μm.

6. The method according to claim 1, wherein the demarginated zone forms a strip at a periphery of the first glass sheet and the opaque zone of the lamination interlayer forms a black, opaque strip at a periphery of said lamination interlayer.

7. The method according to claim 1, wherein the lamination interlayer comprises at least one sheet of polyvinyl acetal.

8. The method according to claim 1, wherein the opaque zone of the lamination interlayer is obtained by depositing a layer of ink.

9. The method according to claim 8, wherein the layer of ink comprises a resin and black pigments, the resin being selected from polyvinyl butyral, ethylene and vinyl acetate copolymers, polyurethanes and epoxy resins.

10. The method according to claim 8, wherein the layer of ink is facing the first glass sheet.

11. The method according to claim 8, wherein the layer of ink is facing the additional glass sheet.

12. The method according to claim 1, wherein the opaque zone of the lamination interlayer is obtained by coloring the interlayer in its body.

13. The method according to claim 1, wherein the opaque zone of the interlayer is obtained by attaching a sheet of an opaque polymer to the interlayer.

14. The method according to claim 1, wherein the additional glass sheet carries, on the face opposite the face facing the lamination interlayer, an additional stack of thin layers, particularly a low-emissivity stack comprising a transparent conductive oxide.

15. A laminated bent glazing comprising a first glass sheet coated on part of one of its faces, with the exception of a demarginated zone, with a stack of thin layers, said first glass sheet being laminated with an additional glass sheet by a lamination interlayer comprising an opaque zone, so that the opaque zone of said lamination interlayer is arranged facing the demarginated zone and the stack of thin layers is facing the lamination interlayer.

16. The method according to claim 1, wherein the laminated bent glazing is a motor vehicle windscreen or roof.

17. The method according to claim 2, wherein the at least one functional layer is an electrically conductive functional layer.

18. The method according to claim 17, wherein the electrically conductive functional layer is a silver or niobium layer, or an indium tin oxide layer, or a doped tin oxide layer or a doped zinc oxide layer.

19. The method according to claim 3, wherein the at least one phosphate is an alkaline phosphate.

20. The according to claim 5, wherein the thickness of the washable dissolving layer is between 10 and 40 μm.

Description

EXAMPLES

[0089] The following exemplary embodiments illustrate the invention in a non-limiting manner, in connection with FIGS. 1 to 6, wherein:

[0090] FIG. 1 schematically illustrates one embodiment of the method according to the invention.

[0091] FIG. 2 illustrates one example of a glazing obtained according to the invention.

[0092] FIG. 3 schematically illustrates another embodiment of the method according to the invention.

[0093] FIG. 4 schematically illustrates another embodiment of the method according to the invention.

[0094] FIG. 5 schematically illustrates another embodiment of the method according to the invention.

[0095] FIG. 6 schematically illustrates another embodiment of the method according to the invention.

[0096] FIGS. 1 and 3 to 6 depict a schematic cross-section of part of the glass sheets and elements deposited on the glass sheets, near the periphery of the latter, during the steps of the method. The various elements are obviously not depicted to scale, so as to be able to visualize them.

[0097] The first glass sheet 10 coated with the stack of thin layers 12 is provided in step a, then a part of the stack 12 is coated by a washable dissolving layer 14, particularly by screen printing (step b), in a zone 16 referred to as “zone to be demarginated”, intended to be placed substantially at an opaque zone in the final glazing.

[0098] In step c, the first glass sheet undergoes a pre-firing treatment leading in the zone 16 to a dissolution of the stack 12 by the washable dissolving layer 14. After washing (step d), which results in the elimination of the washable dissolving layer 14, the first glass sheet 10 has a bare glass surface in the demarginated zone 17.

[0099] An additional glass sheet 20, herein provided with an additional stack of thin layers 22, is then placed on the first glass sheet 10, and the whole is then bent (step e). Since the depicted view only shows the end of the glass sheet, the bending is not depicted herein.

[0100] In step f, a lamination interlayer 30 is provided. This interlayer 30 has an opaque zone 32 in the form of a layer of ink 34.

[0101] In step g, the first glass sheet 10 coated with the stack of thin layers 12 and the additional glass sheet 20 coated with the additional stack 22 are assembled by means of the lamination interlayer 30. The diagram herein depicts each of the separate elements, in exploded view. The stack 12, facing the lamination interlayer, is positioned in the final glazing on face 2. The opaque zone 32 is positioned facing the zone 16. In the embodiment depicted in FIG. 1, the layer of ink 34 faces the first glass sheet 10, thus face 2 of the final glazing.

[0102] FIG. 2 depicts an example of glazing according to the invention, in this case a windscreen. The opaque zone 32 is presented in the form of a peripheral strip whose width depends on its position on the glazing. The strip herein has a small width in the side zones, a large width in the lower zone, and a variable width in the upper zone, the opaque strip hiding in the central upper zone the means for positioning the central rear-view mirror and providing in this zone transmission windows for sensors and cameras, such as rain or light sensors or driving-assistance cameras or even lidars.

[0103] FIGS. 3 to 6 illustrate configurations other than FIG. 1. In the embodiment of FIG. 3, the layer of ink 34 faces the additional glass sheet 20. In the embodiments of FIGS. 4 to 6, the opaque zone of the lamination interlayer does not exactly match the demarginated zone of the first glass sheet. In FIG. 4, there is a slight space e between the two zones, typically of at most 1 mm, or even of at most 0.5 mm. In FIG. 5 conversely, an overlap r (or covering) is provided. In FIG. 6, this overlap is made less visible by virtue of a gradation of dots 36 obtained during the screen printing of the ink. As previously indicated, a possible overlap is also made less visible when the layer of ink faces the additional glass sheet (thus faces face 3 in the illustrated example).

[0104] The method carried out by the example corresponds to the embodiment of FIG. 1.

[0105] A glass sheet 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, was coated, on a peripheral strip, by screen printing of a washable dissolving layer with a wet thickness of 25 μm. The deposited composition was a sodium phosphate based paste marketed by the company Ferro with reference TDF9283.

[0106] After drying (between 100 and 250° C., 1 to 2 minutes) a step of pre-firing at about 600° C. allowed the washable dissolving layer to dissolve the stack of thin layers. A washing step then made it possible to eliminate the washable dissolving layer.

[0107] After pairing with an additional glass sheet of soda-lime-silica glass with

[0108] a stack comprising a layer of ITO on face 4, the whole was bent at over 600° C. during 350 to 500 seconds. The two glass sheets were laminated together by means of a PVB interlayer, coated in a peripheral area with a black, screen-printed ink.

[0109] After assembly, the appearance, more particularly the black color viewed from face 1, was assessed by measuring the lightness L* in reflection (illuminant D65, reference observer 10°). The measured value of L* was in the range between 2 and 3.