Sheet of glass including an enameled area

Abstract

The invention relates to a material comprising a glass sheet (10) having one face comprising an enameled area (2), such that in said enameled area (2) the glass sheet (10) is coated with an opaque mineral layer (12) and, under at least a portion of said opaque mineral layer (12), with a transparent mineral coating (14) which is not an enamel, said transparent mineral coating (14) comprising, in said enameled area (2), a first zone (Z1) in which the transparent mineral coating (14) has a first thickness (e1) and a second zone (Z2) in which the transparent mineral coating (14) has a second thickness (e2), said first and second thicknesses being different. Figure 1

Description

Title of the invention: Glass sheet comprising an enameled area

[0001] The invention relates to the field of glazing, in particular glazing for buildings or for transport vehicles.

[0002] It is known to coat glass sheets, over all or part of their surface, with opaque mineral layers, in particular with opaque enamel layers. An enamel is a layer comprising a vitreous or vitreous binder and pigments, obtained by depositing a fluid enamel composition comprising a glass frit, pigments, and an organic medium, and then firing it. Enamel layers are often decorative but can also provide masking and protective functions, for example, against ultraviolet radiation.

[0003] The invention aims to provide enameled glazing having a decorative appearance when viewed from the opposite side to the side bearing the opaque layer and which can be manufactured in a simple and economical way.

[0004] For this purpose, the invention relates to a material comprising a sheet of glass, one face of which includes an enameled area, such that in said enameled area the sheet of glass is coated with an opaque mineral layer and, under at least a part of said opaque mineral layer, with a transparent mineral coating which is not an enamel, said transparent mineral coating comprising, in said enameled area, a first area in which the transparent mineral coating has a first thickness and a second area in which the transparent mineral coating has a second thickness, said first and second thicknesses being different.

[0005] The invention also relates to a method for obtaining such a material, comprising the deposition, on one face of a sheet of glass and in an area called the enameled area, of a transparent mineral coating which is not an enamel, and then, on this transparent mineral coating, of an opaque mineral layer, said transparent mineral coating comprising, in said enameled area, a first area in which the transparent mineral coating has a first thickness and a second area in which the transparent mineral coating has a second thickness, said first and second thicknesses being different.

[0006] The invention also relates to glazing comprising a material according to the invention.

[0007] The inventors were able to demonstrate that the presence of a transparent mineral coating and the existence of multiple zones in which the transparent mineral coating has a different thickness make it possible to create a design visible from the side opposite the enameled face. The reflective appearance of the enamel is modulated by the thickness of the underlying coating, and the contrast between the different This allows for the creation of a decorative effect. This decoration is also achieved in a very simple way, using a single opaque mineral layer (in particular enamel) and possibly after a single firing stage.

[0008] The glass sheet is preferably made of soda-lime silico-glass. It is advantageously obtained by flotation. However, other glass compositions are possible, for example, borosilicate or aluminosilicate type compositions.

[0009] The glass sheet may be clear or tinted, for example, green, gray, bronze, or blue. In the case of tinted glass, the chemical composition of the glass sheet advantageously comprises iron oxide in a weight content ranging from 0.5 to 2.5%. It may also comprise other coloring agents, such as cobalt oxide, chromium oxide, nickel oxide, erbium oxide, or selenium. In the case of clear glass, the chemical composition of the glass sheet advantageously comprises iron oxide in a weight content ranging from 0.01 to 0.15%.

[0010] The glass sheet preferably has a thickness of between 0.7 and 19 mm, in particular between 1 and 6 mm, or even between 2 and 4 mm. The glass sheet preferably has a surface area of ​​at least 1 m².

[0011] The glass sheet can be flat or curved. It is generally flat during the deposition stages of the transparent mineral coating and the opaque mineral layer. However, certain deposition techniques, particularly digital printing, allow these coatings to be deposited on a curved sheet. In the case of vehicle glazing, especially for motor vehicles, it is preferably subsequently curved and therefore has a curved shape in the final glazing.

[0012] The term "enameled area" generally refers to the area covered by the opaque mineral layer, which is most often an enamel layer, but not necessarily, as detailed later in the text.

[0013] The enameled area can cover all or part of the surface of the glass sheet, depending on the intended application. It can cover the entire surface of the glass sheet, for example, in the case of sills. Alternatively, it can cover only a portion of the surface of the glass sheet, in particular from 2 to 80%, or even from 5 to 50% or from 10 to 25%. In the case of vehicles, particularly motor vehicles, the enameled area preferably takes the form of a peripheral band. By "peripheral band" is meant a closed band which, from each point on the periphery of the glass sheet, extends inwards towards the center of the glass sheet over a certain width, typically between 1 and 20 cm.This peripheral strip is intended to conceal and protect against ultraviolet radiation the polymer seals used for fixing and positioning the glazing in the body bays, as well as various mechanical or electrical elements (circuits of . heating, rearview mirror bases, sensors or cameras...).

[0014] According to one embodiment, the transparent mineral coating is in contact with the glass sheet. In this case, the glass sheet is preferably coated, in the enameled area, only by the coating and by the opaque mineral layer.

[0015] Alternatively, other layers or stacks of layers may be interposed between the glass sheet and the transparent mineral coating. These may, for example, be thin films or stacks of thin films comprising at least one functional layer, for example, an electrically conductive or low-emissivity layer, in particular silver-based or based on an electrically conductive transparent oxide (TCO) such as indium tin oxide or doped tin or zinc oxides. Such layers or stacks may, in particular, perform heating (defrosting, demisting) and / or solar control and / or thermal insulation functions.

[0016] The opaque mineral layer is preferably in contact with the transparent mineral coating.

[0017] The transparent mineral coating is present under at least part of the opaque mineral layer. It may be present under the entire opaque mineral layer, therefore throughout the whole glazed area. Alternatively, it may be present under only part of the opaque mineral layer, for example, under 2 to 80%, in particular 10 to 60% of the opaque mineral layer. This is the case, for example, when the transparent mineral coating is intended to create a decorative effect in only part of the glazed area.

[0018] In both cases described above, the transparent mineral coating may also be present on all or part of the un-enameled area, if such an area exists. It may then be present on the entire sheet of glass. This is the case, for example, when the transparent mineral coating has another function, also useful in the view through the glazing, for example an optical function, particularly an anti-reflective one.

[0019] The presence of a transparent mineral coating allows the appearance of the enamel as seen in reflection through the glass sheet to be modified. It has been found that this appearance differs depending on the thickness of the coating. The existence of multiple areas where the coating has different thicknesses thus makes it possible to obtain a different appearance in each area, giving the possibility of creating a decorative effect.

[0020] The decoration can be of any kind: various patterns, for example geometric, logos etc... As an example, the decoration can provide a transition zone between the body of a vehicle and the view through the glazing.

[0021] In order to obtain an attractive finish, the transparent mineral coating preferably has high light transmission. The transparent mineral coating is preferably such that, when deposited on a sheet of clear glass, the light transmission factor is at least 70%, in particular at least 80%, or even at least 88%. Clear glass is defined as glass whose chemical composition comprises iron oxide as the sole colorant in a weight content of between 0.05 and 0.12%. Planiclear® glass, marketed by the Applicant, is an example of clear glass.

[0022] The transparent mineral coating is preferably colorless (in other words, untinted). In particular, the colorimetric coordinates a* and b* (illuminant D65, observer CIE-1964) in transmission of the transparent mineral coating seen through a clear glass sheet are preferably between 0 and 5, in particular between 0 and 2, or even between 0 and 1.

[0023] According to one embodiment, the transparent mineral coating comprises a single layer. The existence of areas of different thicknesses is then obtained by locally varying the thickness of the single layer during its deposition.

[0024] According to another embodiment, the transparent mineral coating comprises, at least in the first or second zone, a plurality of superimposed layers, in particular two, three, or four layers. In this case, the coating thickness in a zone corresponds approximately to the sum of the thicknesses of each of the layers forming the coating in that zone. The coating thickness may not correspond exactly to the sum of the thicknesses of each of the layers when the deposition of one layer results in a slight reduction in the thickness of the layer below. These layers are generally of the same chemical composition, but they may alternatively be of different chemical compositions. The existence of zones of different thicknesses is then obtained by depositing a different number of layers in each zone. Thus, the number of layers forming the coating in a first zone is different from the number of layers forming the coating in a second zone.As an example, the coating may consist of a single layer in a first zone and two layers in a second zone, the thickness of the coating in the second zone then being different from that of the coating in the first zone, typically double if the layers have the same thickness.

[0025] Regardless of the embodiment, the number of zones corresponding to different thicknesses is not limited to two. The transparent mineral coating may therefore have, in addition to a first and a second zone, a third zone in which the coating has a third thickness, different from the first and second thicknesses. Generally, the transparent mineral coating may comprise N zones Zx (N being at least 2 and x ranging from 1 to N), the thickness ex of the transparent mineral coating in zone Zx being different from the thickness ey of the transparent mineral coating in zone Zy, for all x different from y. For For reasons of simplicity, N is preferably at most 10, or even at most 8 and even at most 5.

[0026] By zone we must understand zones located in the plane of the coating.

[0027] The visual appearance in reflection of the opaque layer seen through the glass sheet can be varied depending on the thickness of the transparent mineral coating and its refractive index.

[0028] The thickness of the transparent mineral coating in each zone (first, second, or even third and more) is preferably between 30 and 1000 nm, in particular between 50 and 500 nm, or even between 60 and 300 nm.

[0029] Preferably, the ratio between the second thickness and the first thickness is at least 1.2, in particular at least 1.5, or even at least 1.8. It is generally at most 4, or even at most 3. In general, when the transparent mineral coating comprises N Zx zones, the ratio between the thickness in the Zx zone and the thickness in the Zx4 zone is preferably at least 1.2, in particular at least 1.5, or even at least 1.8, and often at most 4 or at most 3.

[0030] The refractive index of the transparent mineral coating (typically for a wavelength of 550 nm) is preferably between 1.3 and 2.4, particularly between 1.4 and 2.0. The refractive index, as well as the thickness of the transparent mineral coating, can influence the perceived color. In the case where the transparent mineral coating is formed of a plurality of layers of different chemical compositions, the refractive index of the coating corresponds to the average of the refractive indices of each of the layers, weighted by the thickness of each of the layers.

[0031] The transparent mineral coating is preferably based on an oxide, nitride, or oxynitride of one or more elements selected from Si, Zr, Ti, Zn, Sn, and Al. Preferred oxides are silicon, zirconium, and titanium oxides. Preferably, the transparent mineral coating is silicon oxide-based, and in particular, is composed of silicon oxide. The choice of element allows for adjusting the refractive index of the coating. Silicon oxide (also called silica) has a refractive index of approximately 1.4.

[0032] The transparent mineral coating is preferably a sol-gel coating. In this case, the coating is deposited using a sol-gel process. The sol-gel coating is preferably based on, or even composed of, silicon oxide. By "based on," it is meant that the coating comprises at least 50% by weight of silicon oxide. It may contain other oxides, for example titanium or zirconium, in order to vary the refractive index of the coating.

[0033] A sol-gel process is a process in which a sol containing precursors of the coating to be produced is deposited onto the glass sheet by various means, such as the spraying, curtain, laminar coating, roller, screen printing, inkjet deposition etc.... Screen printing or inkjet deposition is preferred here since it easily allows the coating to be deposited only in the desired areas.

[0034] The ground preferably contains organometallic precursors of the coating to be produced, for example tetraethyl orthosilicate (TEOS). The coating is then generally dried before the enamel layer is applied and then annealed to densify it. The annealing preferably takes place during the same step as the enamel firing, generally during the bending and / or quenching of the glass sheet.

[0035] Alternatively, the coating can be deposited using PVD or CVD (chemical vapor deposition) methods, for example by sputtering, or by plasma-enhanced chemical vapor deposition (PECVD), possibly under atmospheric pressure (APPECVD). Masks can then be used to deposit the coating only in the desired areas. However, these methods are more complex than screen printing or inkjet printing.

[0036] In the case where the transparent mineral coating comprises, at least in the first or second zone, a plurality of superimposed layers, the coating deposition process includes successive steps of deposition of each of the layers. For example, it is possible to carry out successive screen printing passes using different screen printing screens. A drying step is preferably implemented between two successive layer deposition steps, typically at a temperature between 120 and 200°C.

[0037] When the transparent mineral coating comprises a single layer, the coating deposition involves only one deposition step. In the case of screen printing deposition, obtaining areas of different thicknesses in a single step can be achieved by various means, notably those described in application W2018 / 229449.

[0038] Generally, the opaque mineral layer is usually a layer comprising pigments in a mineral binder. The opaque mineral layer is preferably an enamel or a silicate paint.

[0039] The layer is opaque, which means that the light transmission factor in the enameled area is less than 0.1%, in particular is zero.

[0040] At least one, and in particular each, pigment is preferably based on an oxide or sulfide of iron, chromium, copper, cobalt, titanium, and / or manganese. The color of the pigments, and therefore of the opaque mineral layer, is not limited: white, black, blue, red, yellow, green, etc. In the case of vehicle glazing, particularly for automobiles, the pigments are preferably black. The opaque mineral layer is then black and advantageously has a colorimetric coordinate L* on the reflected side of the enameled surface of less than 5, in particular 3. This measurement excludes specular reflection.

[0041] The term "silicate paint" refers to a layer obtained from an aqueous paint composition comprising pigments and an aqueous solution of alkali silicate. The layer therefore comprises pigments bound together by a silicate binder.

[0042] The aqueous alkali silicate solution preferably comprises at least one sodium, potassium, and / or lithium silicate. The aqueous alkali silicate solution may consist of a mixture of different aqueous alkali silicate solutions, for example, a mixture of at least one aqueous sodium solution and at least one aqueous potassium solution.

[0043] The paint composition preferably comprises at least one mineral filler, in particular selected from colloidal silica, feldspars, alumina, and lamellar fillers. The lamellar fillers are preferably selected from talc, mica, and clays, in particular silicate or aluminosilicate clays such as kaolinite, illinite, montmorillonite, and sepiolite. The paint composition advantageously comprises a mixture of several of these mineral fillers.

[0044] Mineral fillers and pigments preferably have a granulometric (by volume) distribution such that their d90 is less than 10 pm.

[0045] The paint composition may also include a base, in particular an alkali hydroxide.

[0046] The paint composition may further contain various additives, such as at least one dispersing agent, at least one anti-foaming agent, at least one thickening agent, at least one stabilizing agent and / or at least one hardening agent.

[0047] In the mineral paint layer, the weight content of alkali silicate is preferably between 7% and 60%, in particular between 15% and 55%. The total weight content of mineral pigments and fillers is preferably between 20% and 90%, in particular between 30% and 70%. The total content of additives is preferably between 0.1% and 5%. These contents also apply to the composition of aqueous paint (in which case they are percentages relative to the dry extract).

[0048] By enamel layer we mean both the layer before firing and after firing.

[0049] Before firing, the enamel layer comprises a glass frit, pigments, and an organic medium. After firing, the enamel layer comprises pigments and a vitreous or vitreous matrix obtained by melting the glass frit. The glass frit and / or the vitreous matrix is ​​preferably made of zinc and / or bismuth borosilicate glass.

[0050] The enamel layer is preferably obtained by screen printing a fluid enamel composition comprising a glass frit, pigments, and an organic medium. To do this, the enamel composition is deposited, notably using a squeegee, onto the glass sheet through the mesh of a screen printing screen. The screen mesh is blocked in the areas corresponding to the zones of the glass sheet that are not It does not want to be coated, so the enamel composition can only pass through the screen in the areas to be printed, according to a predefined pattern. Other deposition techniques, such as digital printing techniques, for example inkjet, are also possible.

[0051] In general, the opaque mineral layer, therefore also the silicate paint layer, is advantageously deposited by these different techniques, in particular by screen printing or by digital printing, especially inkjet printing.

[0052] Before firing, the opaque mineral layer, in particular the enamel layer, preferably has a thickness of between 10 and 30 µm, in particular between 15 and 25 µm. After firing, the thickness of the opaque mineral layer, in particular the enamel layer, is preferably between 5 and 15 µm, in particular between 7 and 13 µm.

[0053] The process according to the invention preferably includes a firing step of the opaque mineral layer, in particular the enamel layer, generally during the tempering and / or bending of the glass sheet. Where applicable, this step also serves to densify the sol-gel underlayer. This step preferably involves temperatures ranging from 550 to 720°C. The invention thus makes it possible to create a decoration with a single firing step.

[0054] In the case of silicate paint, the coated glass sheet may undergo a pre-baking step, intended to harden the paint layer before a possible tempering and / or curing step. Mineral paints based on alkali silicates can usually be cured at moderate temperatures, in the range of 200 to 250°C.

[0055] Bending can be achieved, in particular, by gravity (the glass deforming under its own weight) or by pressing, at temperatures typically ranging from 550 to 650°C. In the case of laminated glazing, the two glass sheets can be bent together (which is the preferred method) or separately. The process may also include, before the bending step, a pre-baking step of the first glass sheet coated with the opaque layer, preferably at a temperature between 450 and 600°C. Such pre-baking eliminates the organic medium, or more generally any organic component that may be present in the opaque layer, and improves the latter's non-stick properties. It is indeed important to avoid any sticking between the opaque layer and the other glass sheet, or between the opaque layer and the bending tools.

[0056] The glazing according to the invention may comprise a single sheet of glass. In this case, the sheet of glass is preferably thermally tempered. It may alternatively be hardened or annealed.

[0057] Alternatively, the glazing may be laminated glazing, in which the glass sheet of the material according to the invention is adhesively bonded to another glass sheet by means of a laminating interlayer, for example made of polyvinyl butyral. In this case, the glass sheets are therefore not thermally tempered.

[0058] In the case of laminated glazing, the opaque mineral layer, in particular the enamel layer, is preferably located on face 2 or face 4, that is to say respectively the face opposite the face (called 1) facing outwards (of the vehicle or building) or the innermost face. In this case, the design is visible from the outside.

[0059] The glazing can also be multiple glazing, for example double or triple, in which the glass sheet of the material according to the invention is linked to at least one other glass sheet by means of a peripheral interlayer frame, typically made of metal or polymer material.

[0060] The glazing according to the invention can be vehicle glazing (land, air, sea), in particular motor vehicle glazing, such as rear window, windshield, side window, roof, roof panel or quarter window.

[0061] The glazing can alternatively be building glazing, for example used in a facade or in a window, or be furniture or decoration glazing (partitions, doors, tables etc...).

[0062] The following examples illustrate the invention in a non-limiting manner.

[0063] [Fig-1] illustrates an embodiment of the invention, used in the example. More precisely Specifically, it illustrates a schematic cross-sectional view of a material according to the example. The thicknesses of the different elements are obviously not shown to scale.

[0064] A sol-gel silica coating 14 was deposited on a portion of a sheet of clear float glass (sold under the reference Planiclear® by the Applicant). This transparent mineral coating 14 was applied by screen printing and comprised three zones Zi to Z3.

[0065] In a first zone Zb, the coating 14 consisted of a single layer of silica 14b. In a second zone Z2, the coating 14 consisted of two superimposed layers of silica (14i and 142). In a third zone Z3, the coating consisted of three superimposed layers of silica (14b, 142, and 143). In this example, the thicknesses (e1, e2, and e3) of each of the silica layers were substantially identical. The coating 14 was deposited in three successive screen-printing steps, with a drying step at 160°C for 180 seconds after each screen-printing step. Each layer had a wet thickness of approximately 10 µm.

[0066] On the coating 14, as well as on the part of the glass sheet 10 not coated by the coating 14, a layer of black enamel 12 was deposited. The deposit was also made by screen printing, and the thickness of wet enamel was about 25 µm.

[0067] After drying (160°C, 180 seconds), the glass sheet was tempered by heating it to 690°C and then rapidly cooling it using air nozzles.

[0068] After quenching, the visual appearance seen from the side of the uncoated sheet was characterized in reflection (specular reflection excluded) using a spectrocolorimeter, and the results are presented in the table below.

[0069] [Tables 1] Zone L* a* b* Email only 3.7 0.1 0.4 Z1 4.0 0.1 -0.6 Z2 6.4 -0.3 -1.1 Z3 9.1 -0.6 -1.7

[0070] The results show that, in the case of a black enamel, the areas containing the silica coating exhibit a grayer tint in reflection, with the grayness increasing with the thickness of the coating. The contrast between the different areas is sufficient to make the decorations perfectly visible.

Claims

Demands

1. Material comprising a sheet of glass (10) having one face comprising an enameled area (2), such that in said enameled area (2) the sheet of glass (10) is coated with an opaque mineral layer (12) and, under at least a part of said opaque mineral layer (12), with a transparent mineral coating (14) which is not an enamel, said transparent mineral coating (14) comprising, in said enameled area (2), a first zone (Zi) in which the transparent mineral coating (14) has a first thickness (ei) and a second zone (Z2) in which the transparent mineral coating (14) has a second thickness (e2), said first and second thicknesses being different.

2. Material according to claim 1, wherein the opaque mineral layer (12) is an enamel or a silicate paint.

3. Material according to any one of the preceding claims, wherein the transparent mineral coating (14) comprises, at least in the first (Zi) or in the second zone (Z2, Z3) a plurality of superimposed layers (14b 142 , 143).

4. Material according to any one of the preceding claims, wherein the transparent mineral coating (14) comprises N zones Zx (Zb Z2, Z3), N being at least 2 and x ranging from 1 to N, the thickness ex of the transparent mineral coating (14) in zone Zx being different from the thickness ey of the transparent mineral coating in zone Zy, for any x different from y.

5. Material according to any one of the preceding claims, wherein the ratio between the second thickness (e2) and the first thickness (ei) is at least 1.2, in particular at least 1.

5.

6. Material according to any one of the preceding claims, wherein the transparent mineral coating (14) is based on an oxide of one or more elements selected from Si, Zr, Ti, Zn, Sn and Al, in particular based on silicon oxide.

7. Material according to any one of the preceding claims, wherein the transparent mineral coating (14) is a sol-gel coating.

8. A method for obtaining a material according to any one of the preceding claims, comprising depositing, on one face of a glass sheet (10) and in a so-called enameled area (2), a transparent mineral coating (14) which is not an enamel, and then, on this transparent mineral coating (14), an opaque mineral layer (12), said coating transparent mineral (14) comprising, in said enamelled zone (2), a first zone (Zi) in which the transparent mineral coating (14) has a first thickness (ej and a second zone (Z2) in which the transparent mineral coating (14) has a second thickness (e2), said first and second thicknesses being different.

9. A method according to the preceding claim, wherein the deposition of the transparent mineral coating (14) is carried out by a sol-gel process, and wherein the opaque mineral layer (12) is deposited by screen printing or by digital printing.

10. Glazing comprising a material according to any one of claims 1 to 7.