METHOD FOR PRODUCING A CURVED LAMINATED GLAZING
A method for obtaining a laminated curved glazing unit in which (a) a first glass sheet is provided, coated on at least part of one of its faces with a stack of thin layers, then (b), on part of the surface of the stack of thin layers, an enamel layer is deposited by screen-printing an enamel composition comprising 1 to 15% by weight of zinc oxide particles having a particle size distribution by volume such that the d90 is at most 5 μm. After lamination (d) with an additional glass sheet, the enamel layer is turned towards a lamination interlayer.
1 . A method for obtaining a curved laminated glazing unit, comprising the following successive steps:
a. providing a first glass sheet, covered on at least part of one of its surfaces with a stack of thin layers,
b. a step of depositing, on a part of a surface of the stack of thin layers, a layer of enamel, the deposition being carried out by screen-printing an enamel composition comprising 1 to 15% by weight of zinc oxide particles having a particle size distribution by volume such that d90 is at most 5 μm,
c. a step of bending the first glass sheet, the stack of thin layers located under the enamel layer being completely dissolved by said enamel layer at least at the end of said step c, then
d. a step of laminating said first glass sheet with an additional glass sheet by means of a lamination interlayer, so that the enamel layer faces said 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 15 , wherein the electrically conductive functional layer is selected from metal layers, and layers of a transparent conductive oxide.
4 . The method according to claim 1 , wherein after step d, the enamel layer is opaque, has a black hue, and forms a strip at a periphery of the first glass sheet.
5 . The method according to claim 1 , wherein the zinc oxide particles have a particle size distribution by volume such that the d90 is at most 1 μm.
6 . The method according to claim 1 , wherein the zinc oxide particles have a particle size distribution by volume such that the d50 is between 200 and 900 nm.
7 . The method according to claim 1 , wherein a proportion of zinc oxide particles in the enamel composition is between 2 and 10% by weight.
8 . The method according to claim 1 , wherein the enamel composition further comprises refractory particles having a diameter of at least 20 μm in a volume proportion of at least 0.5%, but not particles having a diameter greater than 80 μm.
9 . The method according to claim 8 , wherein the refractory particles are based on metal oxides or metals.
10 . The method according to claim 1 , wherein the deposition of the enamel layer is carried out by screen printing using a screen printing screen having a mesh opening of at least 40 μm.
11 . The method according to claim 1 , wherein:
the method comprises between step b) and step c) a step b1) of pre-firing the enamel layer during which the thin layer stack located under the enamel layer is at least partially dissolved by said enamel layer, and
in step c) the first glass sheet and the additional glass sheet are curved together with the enamel layer facing said additional glass sheet .
12 . The method according to claim 1 , wherein the additional glass sheet bears, on the face opposite the face which is facing the lamination interlayer, an additional stack of thin layers.
13 . A laminated curved glazing unit, especially for a windshield or roof of a motor vehicle, obtained by the method of claim 1 , comprising a first glass sheet coated on at least part of one of its faces with a stack of thin layers, said first glass sheet being coated on part of its surface with an enamel layer comprising zinc oxide particles having a particle size distribution by volume such that the d90 is at most 5 μm, said first glass sheet being laminated with an additional glass sheet by means of a lamination interlayer), said enamel layer facing said lamination interlayer.
14 . The method according to claim 1 , wherein the curved laminated glazing unit is a windshield or roof of a motor vehicle.
15 . The method according to claim 2 , wherein the stack of thin layers comprises at least one electrically conductive functional layer.
16 . The method according to claim 3 , 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.
17 . The method according to claim 6 , wherein the zinc oxide particles have a particle size distribution by volume such that the d50 is between 300 and 800 nm.
18 . The method according to claim 7 , wherein a proportion of zinc oxide particles in the enamel composition is between 3 and 8% by weight.
19 . The method according to claim 12 , wherein the additional stack of thin layers is a stack with low emissivity comprising a transparent conductive oxide.