WO2025238233A1 - Glass article, method for obtaining same and motor vehicle glazing unit comprising such a glass article - Google Patents

Abstract

The invention relates to a glass article comprising: a glass substrate, and an opaque first layer at least partially covering a surface of the glass substrate and comprising at least one glass frit and at least one pigment, the glass article being intended to be positioned in the vicinity of at least one bodywork element of the vehicle, the at least one pigment being selected such that the glass article has a colorimetric appearance similar to the bodywork element. The invention also relates to a method for obtaining the glass article, comprising a step of depositing the first layer on the glass substrate. Lastly, the invention relates to a motor vehicle glazing unit comprising the glass article.

Description

Description

Glass article, its production process and automotive glazing including such a glass article

Previous technique

The invention relates to the field of glazing, in particular glazing for motor vehicles, for example windshields, rear windows, side windows, quarter windows or roofs.

Automotive glazing must meet a large number of requirements, in terms of both safety and comfort.

Such glazing is often monolithic, comprising a single sheet of thermally tempered glass.

Alternatively, and to improve both safety and acoustic comfort, a growing number of windows are laminated, meaning they consist of two sheets of glass bonded together with a lamination interlayer. This interlayer not only holds glass fragments together in case of breakage, but also provides other functional benefits, particularly in terms of burglary resistance and improved acoustic properties.

Layers of enamel, usually black and opaque, are often applied to part of the glazing, generally as a peripheral band designed to protect the polymer seals used to fix and position the glazing in the bodywork openings from ultraviolet radiation. They also serve to conceal these seals as well as other elements located on the vibration, such as electrical connections or collector strips, designed to collect electricity.

An enamel is a mineral layer formed by firing an enamel composition comprising a glass frit, particularly bismuth borosilicate glass, and pigments.

In an effort to differentiate vehicles through their design, car manufacturers are also looking for original decorative elements, particularly those visible from the exterior of the vehicle, without compromising safety or the occupants' comfort in terms of lighting and temperature. Designs that create a smooth transition between the bodywork and the view are especially sought after.

It is known in particular from document WO 2023/208956 Al to use dichroic materials for their property of reflecting incident light into reflected rays of different wavelengths, making it possible to create a smooth transition zone between the bodywork and the view. In the building sector, it is also known, for example from document WO 2017/191655 Al, to use reflective enameled layers for aesthetic purposes.

Description of the invention

The present invention therefore proposes, in order to obtain decorations enabling the creation of a smooth transition zone between the bodywork and the view in the field of automotive glazing, to implement such materials.

To describe such a transition, we speak of a "seamless" effect.

Accordingly, and in a first aspect, the invention relates to a glass article comprising:

• a glass substrate, and

• a first opaque layer covering at least partially a surface of the glass substrate and comprising at least one glass frit and at least one pigment, said glass article being intended to be positioned in the vicinity of at least one bodywork element of the vehicle characterized in that said at least one pigment is selected so that the glass article has a colorimetric appearance similar to the bodywork element.

In this particular glass article, different colors are achieved depending on the pigment(s) used. The color, and therefore the pigments used, are chosen according to the color of the car body with which the "seamless" effect is desired.

Since the first layer is opaque, i.e., has zero light transmission, the glass article therefore also has zero light transmission in the areas covered by said first layer.

In one particular embodiment, the first layer is a glaze, comprising a glass frit, at least one pigment, and an organic medium before firing, and then at least one pigment and a vitreous matrix obtained by melting the glass frit after firing. The term "glaze" refers to the layer both before and after firing. Glazes are typically obtained by firing above 500 °C.

The glass frit and/or the glass matrix is preferably made of zinc borosilicate and/or bismuth glass. Preferably, the glass frit and/or the glass matrix is zinc borosilicate.

In a particular embodiment, the first layer comprises 5% to 15% by weight, in particular 7% to 13% by weight, and preferably 10% by weight of pigment, relative to the total weight of the first layer. In a particular embodiment, the first layer comprises less than 75%, in particular less than 50% and preferably less than 25% by weight of black pigment.

In a particular embodiment, the first layer comprises less than 5%, in particular less than 2%, preferably less than 1% by weight of cadmium and/or lead; better, the first layer is free of lead and/or cadmium.

A layer according to this embodiment is preferred when a layer stacking as described below is used. Such a layer is commercially available, for example, in the Serie 140 range from Ferro.

In a particular embodiment, the first layer has a thickness of 1 pm to 100 pm, in particular from 10 pm to 80 pm and preferably from 15 pm to 50 pm.

In particular, said first layer makes it possible to obtain, by its diffuse aspect when observed through the glass substrate, a colorimetric aspect, that is to say colorimetric coordinates (L*, a*, b*), analogous to the bodywork element in the vicinity of which the glass article according to the invention is intended to be positioned within the vehicle.

The Lab* color space, also known as CIELAB or CIE 1976, was defined by the International Commission on Illumination (CIE) in 1976. It is designed to represent color more perceptually uniformly than other color spaces, such as RGB or CMYK. This means that colors that are close in the Lab* space are also perceived as being close in color. The Lab* color space is based on three dimensions:

• Brightness (L*): This dimension represents the lightness or darkness of a color. An L* value of 0 corresponds to black and an L* value of 100 corresponds to white.

• Red-green (a*): This dimension represents the amount of red or green in a color. A value of a* = 0 corresponds to a neutral gray, positive values of a* represent red, and negative values of a* represent green.

• Yellow-blue (b*): This dimension represents the amount of yellow or blue in a color. A value of b* = 0 corresponds to a neutral gray, positive values of b* represent yellow, and negative values of b* represent blue.

It thus appears that a glass article according to the invention has colorimetric coordinates (L*, a*, b*) close to the bodywork element in the vicinity of which it is intended to be positioned. A parameter for evaluating the colorimetric proximity of two objects, here the glass article according to the invention and the bodywork element in the vicinity of which it is intended to be positioned, is the colorimetric difference AE, expressed by the following equation:

[Maths 1]

AE = j AL* ² + Aa* ² + Ab* ² where AL*, Aa* and Ab* correspond respectively to the differences between the colorimetric coordinates as defined in this text of the glass according to the invention and said bodywork element.

The colorimetric coordinates of the glass article according to the invention and of the bodywork element in the vicinity of which it is intended to be positioned are generally considered close for an AE less than or equal to 10, in particular less than or equal to 5 and preferably less than or equal to 2.5. It is then said that the colorimetric appearance of the glass article is analogous to the bodywork element.

In particular, a glass article according to the invention and a bodywork element having an AE of less than 2.3 can be considered to have the same colorimetric appearance.

The first layer of a glass article according to the invention can substantially cover an entire surface of the glass substrate.

In a particular embodiment, said first layer is deposited directly in contact with the glass substrate.

In another particular embodiment, a stack of layers is arranged between the glass substrate and said first layer.

According to this embodiment, the glass substrate can be partially or totally covered by said stack of layers.

Similarly, the first layer can partially or completely cover the stack of layers.

The layer stack exhibits a light reflection observed on the substrate side, referred to as RG, ranging from 10 to 40%, and in particular from 15 to 35%. This reflection is measured according to the EN 410 standard.

Thus, in a preferred embodiment of the invention, the glass article according to the invention comprises a stack of layers, at least partially covering the surface of the glass substrate and being at least partially covered by the first layer, the entire substrate of glass and stacking exhibiting light reflection observed on the substrate side RG of 10 to 40% and in particular of 15 to 35%.

This embodiment has the advantage, thanks to the stacking of layers and its light reflection, of allowing a greater reflection of light radiation, which contributes to the desired seamless effect.

In particular, said stacking of layers makes it possible to obtain, by its specular aspect when observed through the glass substrate, a colorimetric aspect, that is to say colorimetric coordinates (L*, a*, b*), analogous to the bodywork element in the vicinity of which the glass article according to the invention is intended to be positioned within the vehicle.

A person skilled in the art will readily understand that a stack of layers suitable for the present invention exhibits non-zero light transmission. In particular, said stack can exhibit a light transmission of at least 10% and preferably at least 20%.

In this embodiment, the first layer advantageously fulfills a role of mechanical protection, in particular an anti-scratch role, of the stacking of layers.

A stack of layers suitable for the present invention is advantageously a stack acting on solar radiation, particularly intended for thermal insulation and/or solar protection, i.e. contributing to the thermal comfort of the vehicle.

Such stacks are described for example for applications in the building sector, in document EP 1 218 307 Bl.

In particular, said layer stack comprises at least one functional layer based on a partially or fully nitrided metal. Said metal is selected from niobium, tantalum, and zirconium, preferably niobium. Said functional layer is surmounted by at least one overlayer based on aluminum nitride, aluminum oxynitride, silicon nitride, or silicon oxynitride, or a mixture of at least two of these compounds.

In particular, the stack further comprises, between the glass substrate and the functional layer, at least one underlayer of transparent dielectric material, in particular selected from aluminium nitride, aluminium oxynitride, silicon nitride, silicon oxynitride, or a mixture of at least two of these compounds.

Preferably, the stack consists of a silicon nitride sublayer, a niobium or niobium nitride functional layer, and a silicon nitride toplayer.

In this text, the term "functional layer" refers to the layer(s) of the stack that give the stack its essential thermal properties, as opposed to the other layers. layers, generally made of dielectric material, whose role is that of chemical or mechanical protection of the functional layers, an optical role, an adhesion layer role, etc...

In a particular embodiment, a stack of layers suitable for the invention comprises:

• a functional layer with a thickness of 5 to 50 nm, preferably 8 to

40 nm; and

• an overlayer with a thickness of 5 to 120 nm, preferably 7 to 90 nm.

In a glass article according to the invention, the stacking of layers can substantially cover an entire surface of the glass substrate.

In a glass article according to the invention, the thickness of the first layer can be from 1 pm to 100 pm, in particular from 10 pm to 80 pm and preferably from 15 pm to 50 pm.

A layer stacking as defined in this text advantageously supports the heat treatments to which glass articles are usually subjected in the field, for example tempering, bending or firing of an enamel.

A glass substrate suitable for the invention can be clear or tinted throughout.

Clear glass suitable for the invention is, for example, marketed by the company Saint-Gobain Glass France under the reference Planiclear.

Mass-tinted glass suitable for the invention is, for example, marketed by the company Saint-Gobain Glass France under the reference Parsol, in particular Parsol Green and Parsol Sapphire Blue.

According to another aspect, the present invention relates to a method for obtaining a glass article as defined above, comprising

• Optionally, a magnetron deposition step of the layer stack on at least a portion of the glass substrate surface, and

• a step of depositing the first layer, where appropriate on the stack of layers, and/or on at least part of the surface of the glass substrate.

In one embodiment of the invention, the first layer deposition step is carried out by screen printing, by digital printing and/or by roller application, preferably by digital printing.

Digital printing allows, in particular, for a gradient between the edge and the center of the substrate. Thus, the edge can have a colorimetric appearance particularly close to the bodywork element near which it is intended to be positioned, while the center... As you move towards the center, the amount of first layer deposited decreases, resulting in a color appearance closer to that of a glass item without this first layer. This gradient contributes advantageously to the desired seamless effect.

A screen printing process involves depositing a paste-like liquid onto a substrate, typically using a squeegee, through the mesh of a screen printing screen. The screen mesh is blocked in the areas of the substrate that must remain uncovered, so that the paste can only pass through the screen in the areas to be printed, according to a predefined pattern. The selective blocking of the mesh is therefore performed in reverse of the pattern to be printed.

This selective sealing is generally achieved by applying a photocurable resin to the screen and then exposing the parts of the screen to be sealed to ultraviolet radiation.

Selective exposure is for example achieved using a slide comprising a transparent support, typically made of polyester, coated with an opaque ultraviolet ink deposited according to the pattern to be printed.

The screen mesh is chosen according to the viscosity and surface tension of the paste as well as the desired thickness for the resulting layer of the screen printing deposit.

In a particular embodiment, a process according to the invention further comprises, after the steps of depositing the stack of layers and the first layer, a step of depositing, in particular of screen printing, a solution comprising a phosphate salt on at least a part of the stack of layers not covered by the first layer.

This solution is applied in particular after a drying stage of the glass article.

The solution can be deposited on the entire glass article or on at least a portion of the glass article not covered by the first layer. In particular, the solution is deposited on a portion of the glass article covered by the stack of layers suitable for the invention.

Such a solution is described, for example, in document EP 3 826 972 B 1 and allows for the dissolution of layers (in the context of the present invention: the stack of layers suitable for the invention and/or any layer other than the first layer) in order to obtain a finish corresponding to the glass substrate after a baking step. This finish can reproduce a pattern applied during the deposition of the solution.

According to yet another aspect, the present invention relates to automotive glazing comprising a glass article according to the invention.

In a glazing according to the invention, the surface on which the first layer is spread is called the "enameled zone". The enameled area is presented in particular in the form of a peripheral band. That is to say, a band closed upon itself which, from each point of the glass article according to the invention, extends towards the interior of the glass article over a certain width, typically between 1 and 20 cm.

The remaining part of the automotive glazing according to the invention, called the "non-enameled area", is generally uncoated.

Alternatively, it can be coated with a stack of thin films, for example including a low-emissivity layer, notably silver-based or based on a transparent electrically conductive oxide such as indium tin oxide or doped tin or zinc oxides.

In a particular embodiment, the automotive glazing according to the invention is laminated or tempered glazing.

When the glazing according to the invention is laminated or tempered, the first layer and the stack of layers, when present, can be deposited on the inner face of this glazing.

The term "inner face" refers to any face of a glass pane in the glazing that faces the interior of a vehicle. For example, in tempered glass, this could be the face in contact with the interior of the vehicle, or, in the case of laminated glass, the inner face of the outer pane, that is, the one located on the side of the lamination interlayer.

When the automotive glazing according to the invention is tempered, the tempering of the latter is advantageously carried out simultaneously with the curing of the first layer.

The automotive glazing according to the invention can be curved.

The glass substrate on which the first layer and subsequent layers are deposited is generally flat. This substrate is then preferably curved and thus has a curved shape in the automotive glazing according to the invention.

The curvature of the glazing can enhance the impression of "seamlessness" for an observer. Indeed, compared to flat glass or glass with a less pronounced curve, observation from the same point results in a greater range of viewing angles and thus a greater range of glazing colours, which vary according to the viewing angle due to the reflection made possible by the stacking of thin layers.

When the automotive glazing according to the invention is curved, the curvature thereof is advantageously carried out simultaneously with the curing of the first layer. The glazing according to the invention may include an enameled area comprising 2 to 25%, in particular 3 to 20% and preferably 5 to 15% of the surface of its face coated by the first layer and the stacking of layers.

Claims

Demands 1. Glass article for motor vehicles comprising: • a glass substrate, and • a first opaque layer covering at least partially a surface of the glass substrate and comprising at least one glass frit and at least one pigment, said glass article being intended to be positioned in the vicinity of at least one bodywork element of the vehicle characterized in that said at least one pigment is selected so that the glass article has a colorimetric appearance similar to the bodywork element. 2. Glass article according to the preceding claim, wherein the colorimetric difference AE between the glass article and the bodywork element, expressed where AL*, Aa* and Ab* correspond to the differences between the respective colorimetric coordinates (L*, a*, b*) of the glass article and the bodywork element, is less than or equal to 10, in particular less than or equal to 5 and preferably less than or equal to 2.5. 3. Glass article according to any one of the preceding claims, wherein the first layer substantially covers an entire surface of the glass substrate. 4. Glass article according to any one of the preceding claims, further comprising a stack of layers, covering at least partially the surface of the glass substrate and being at least partially covered by the first layer, the whole of the glass substrate and the stack having a light reflection observed on the substrate side RG of 10 to 40% and in particular of 15 to 35%. 5. Glass article according to the preceding claim, wherein the layer stack comprises at least one functional layer based on a partially or fully nitrided metal, said metal being selected from niobium, tantalum and zirconium, preferably niobium, said functional layer being surmounted by at least one overlayer based on aluminium nitride, aluminium oxynitride, silicon nitride, or silicon oxynitride, or a mixture of at least two of these compounds; in particular the stack further comprises between the glass substrate and the functional layer at least one sublayer of transparent dielectric material, in particular selected from aluminium nitride, aluminium oxynitride, silicon nitride, silicon oxynitride, or a mixture of at least two of these compounds; Preferably the stack consists of a silicon nitride sublayer, a niobium or niobium nitride functional layer and a silicon nitride toplayer. 6. Glass article according to the preceding claim, wherein the stacking of layers comprises: • a functional layer with a thickness of 5 to 50 nm, preferably 8 to 40 nm; and • an overlayer with a thickness of 5 to 120 nm, preferably 7 to 90 nm. 7. Glass article according to any one of claims 4 to 6, wherein the stacking of layers substantially covers an entire surface of the glass substrate. 8. Glass article according to any one of the preceding claims, wherein the first layer comprises less than 75%, in particular less than 50% and preferably less than 25% by weight of black pigment. 9. Glass article according to any one of the preceding claims, wherein the first layer comprises less than 5%, in particular less than 2%, preferably less than 1% by weight of cadmium and/or lead; better, the first layer is free of lead and/or cadmium. 10. Glass article according to any one of the preceding claims, wherein the first layer comprises from 5% to 15% by weight, in particular from 7% to 13% by weight, and preferably 10% by weight of pigment, relative to the total weight of the first layer. 11. Glass article according to any one of the preceding claims, wherein the first layer has a thickness of from 1 pm to 100 pm, in particular from 10 pm to 80 pm and preferably from 15 pm to 50 pm. 12. Glass article according to any one of the preceding claims, wherein the glass substrate is clear or tinted throughout. 13. A method for obtaining a glass article according to any one of the preceding claims, comprising: • Optionally, a magnetron deposition step of the layer stack on at least a portion of the glass substrate surface, and • a step of depositing the first layer, where appropriate on the stack of layers, and/or on at least part of the surface of the glass substrate. 14. Method according to the preceding claim, characterized in that the step of depositing the first layer is carried out by screen printing, by digital printing and/or by roller application, preferably by digital printing. 15. A method according to any one of claims 13 to 14, further comprising, after the steps of depositing the layer stack and the first layer, a step of depositing, in particular by screen printing, a solution comprising a phosphate salt on at least a part of the layer stack not covered by the first layer. 16. Automotive glazing, characterized in that it comprises a glass article according to any one of claims 1 to 12, said glazing being laminated or tempered. 17. Automotive glazing according to the preceding claim, wherein the first layer and the layer stack, when present, is/are arranged on the inner surface.