FR3126974A1 - Rear window or quarter panel of a motor vehicle comprising a sheet of glass - Google Patents

Abstract

The invention relates to a motor vehicle rear window or quarter window (1, 10) comprising a first sheet of glass (2), the face of which intended to be located on the exterior side of the vehicle is coated on at least a part of the latter at least two transparent mineral coatings (4, 12) forming a decoration, identical or different, said at least two mineral coatings being superposed in at least one zone (24, 26, 28) of said outer face. Fig 2

Description

Rear window or quarter panel of a motor vehicle comprising a sheet of glass

The invention relates to the field of rear windows or quarter panels of motor vehicles comprising a sheet of glass.

The object of the invention is to propose rear windows or rear quarter panels of motor vehicles having an attractive decoration, in particular a decoration visible only from outside the vehicle.

To this end, the subject of the invention is a motor vehicle rear window or quarter panel comprising a first sheet of glass, the face of which intended to be located on the exterior side of the vehicle is coated on at least a part thereof with at least two transparent mineral coatings forming a decoration, identical or different, said at least two mineral coatings being superposed in at least one zone of said outer face.

Another object of the invention is a process for obtaining such a motor vehicle rear window or quarter panel, comprising the successive deposition on at least part of one face of a sheet of glass of at least two coatings transparent minerals forming decoration, identical or different, said at least two mineral coatings being superposed in at least one zone of said outer face.

The presence of at least two transparent mineral coatings forming a superimposed decoration makes it possible to confer original optical properties, without however harming the light and thermal comfort of the occupants of the vehicle. More particularly, a decoration can be visible, with good contrast, by people outside the vehicle, but not by the occupants of the vehicle.

In the rest of the text, the rear window or the quarter panel will simply be called "glazing".

The glazing according to the invention is preferably curved, so as to match the curvature of the vehicle. We then distinguish the inner face of the glazing, intended to be located on the inside of the vehicle, which is the concave face, and the outer face of the glazing, intended to be located on the outside of the vehicle, which is the convex face.

According to a first embodiment, the glazing is laminated, that is to say it further comprises an additional sheet of glass adhesively bonded to the first sheet of glass by means of a thermoplastic lamination insert, in particular at polyvinylacetal base. In this case, each sheet of glass has an internal face, facing the interior of the vehicle, and an external face, facing the exterior of the vehicle.

In this embodiment, the first sheet of glass is intended to be located on the exterior side of the vehicle. The face of the first sheet of glass coated with said at least two transparent mineral coatings is then intended to be located on the exterior side of the vehicle. This face is conventionally called “face 1” in the art. In this way, the decor is visible to people outside the vehicle but not to the occupants of the passenger compartment.

According to a second embodiment, the glazing is monolithic, that is to say it only comprises a single sheet of glass, in this case the first sheet of glass. In this case, the first sheet of glass is normally made of tempered glass in order to meet regulatory requirements in terms of safety. Similar to what has been described in the case of laminated glazing, the side coated with the transparent mineral coatings is side 1 (intended to be located outside the vehicle).

The first sheet of glass can be flat or curved. The first sheet of glass is generally flat when the coatings are deposited and is then curved.

The glass of the first glass sheet is typically a silico-soda-lime glass, but other glasses, for example borosilicates or aluminosilicates can also be used. The first sheet of glass is preferably obtained by floating, that is to say by a process consisting in pouring molten glass onto a bath of molten tin.

The first sheet of glass is preferably tinted glass.

It preferably has a light transmission factor of between 2 and 75%, in particular between 5 and 60%, or even greater than 30%, thus making it possible to ensure good contrast, and therefore good visibility of the decoration, but only from the side outside.

To do this, the glass preferably comprises the following coloring elements, in the weight contents defined below: Fe ₂ O ₃ (total iron) from 1.2 to 2.3%, in particular from 1.5 to 2.2 %, CoO from 50 to 400 ppm, in particular from 200 to 350 ppm, Se from 0 to 35 ppm, in particular from 10 to 30 ppm. The redox is preferably between 0.1 and 0.4, in particular between 0.2 and 0.3. Redox means the weight ratio between the ferrous iron content (expressed as FeO) and the total iron content (expressed as Fe ₂ O ₃ ).

According to another embodiment, the glass preferably comprises, as the only coloring element, iron oxide in the weight contents defined below: Fe ₂ O ₃ (total iron) from 0.1 to 1.1%, in particular from 0.5 to 1.0%. The redox is preferably between 0.1 and 0.4.

In this text, the light transmission factors are expressed taking into account the D65 illuminant and the CIE-1931 reference observer. The light transmittance of the glass sheet is obviously measured in the absence of any coating.

The first sheet of glass preferably has a thickness comprised in a range ranging from 0.7 to 19 mm, in particular from 1 to 10 mm, particularly from 2 to 6 mm, or even from 2 to 4 mm.

The lateral dimensions of the first sheet of glass (and, where applicable, of the additional sheet of glass) are to be adapted according to the vehicle in which the glazing is intended to be integrated, more particularly according to the dimensions of the bodywork opening in which the glazing is intended to be fitted. The first sheet of glass (and/or the additional sheet of glass) preferably has a surface of at least 0.5 m², in particular of at least 1 m².

The first glass sheet is preferably coated with a transparent mineral coating on 5 to 90% of the surface of the face of the glass sheet, in particular on 10 to 80%, depending on the desired decoration.

The first sheet of glass, or the additional sheet of glass, is preferably coated with an opaque layer, in particular in enamel, typically in black enamel, in particular placed at its periphery, for example in the form of a peripheral band. The purpose of such a layer is generally to conceal and protect against ultraviolet radiation the polymer seals used for mounting the glazing in the bodywork bay.

This opaque layer is preferably deposited by screen printing.

In the case of laminated glazing, the opaque layer is preferably deposited on the additional sheet of glass.

When the opaque layer and the transparent mineral coatings are deposited on the first sheet of glass, they can be on the same side or on two opposite sides. The order in which the coatings are deposited is irrelevant, but when they are deposited on the same face, it is preferable to deposit the transparent mineral coatings first, then the opaque layer.

According to a preferred embodiment, a low-emissivity coating is interposed between the first sheet of glass and the transparent mineral coating. The normal emissivity of this coating, measured at room temperature, is preferably less than 0.50, in particular 0.30 and even 0.20 or even 0.10.

The refractive index of this coating and, where applicable, its color can influence the final aesthetics of the glazing.

The low-emissivity coating is preferably a stack of thin layers. The stack of thin layers is preferably in contact with the first sheet of glass. It preferably covers all, or at least 90% of the surface of the first sheet of glass.

By “contact”, we mean in this text a physical contact. The expression “based on” preferably means the fact that the layer in question comprises at least 50% by weight of the material considered, in particular 60%, even 70% and even 80% or 90%. The layer may even essentially consist or consist of this material. By “essentially consist”, it should be understood that the layer can comprise impurities without influence on its properties. The terms "oxide" or "nitride" do not necessarily mean that the oxides or nitrides are stoichiometric. They can indeed be under-stoichiometric, over-stoichiometric or stoichiometric.

The stack preferably comprises at least one layer based on a nitride. The nitride is in particular a nitride of at least one element chosen from aluminum, silicon, zirconium, titanium. It may comprise a nitride of at least two or three of these elements, for example a silicon and zirconium nitride, or a silicon and aluminum nitride. Preferably, the layer based on a nitride is a layer based on silicon nitride, more particularly a layer consisting essentially of a silicon nitride. When the silicon nitride layer is deposited by sputtering, it generally contains aluminum, because it is customary to dope silicon targets with aluminum in order to accelerate the deposition rates.

The layer based on a nitride preferably has a physical thickness comprised in a range ranging from 2 to 100 nm, in particular from 5 to 80 nm.

Nitride-based layers are commonly used in a number of stacks of thin layers because they have advantageous blocking properties, in the sense that they prevent the oxidation of other layers present in the stack, in particular functional layers. which will be described below.

The stack preferably comprises at least one functional layer, in particular an electrically conductive functional layer. The functional layer is preferably comprised between two thin dielectric layers, at least one of which is a nitride-based layer. Other possible dielectric layers are for example layers of oxides or oxynitrides.

At least one electrically conductive functional layer is advantageously chosen from:
- the metallic layers, in particular silver or niobium, or even gold, and
- the layers of a transparent conductive oxide, chosen in particular from indium and tin oxide, tin oxides doped (for example with fluorine or antimony), zinc oxides doped (for example aluminum or gallium).

These layers are particularly appreciated for their low emissivity, which gives the glazing excellent thermal insulation properties. In the glazing fitted to motor vehicles, low-emissivity glazing makes it possible in hot weather to reflect part of the solar radiation outwards, and therefore to limit the heating of the passenger compartment of said vehicles, and if necessary to reduce the air conditioning expenses. Conversely, in cold weather, these glazings allow the heat to be retained within the passenger compartment, and therefore reduce the energy cost of heating.

According to a preferred embodiment, the stack of thin layers comprises at least one layer of silver, in particular one, two or three, or even four layers of silver. The physical thickness of the silver layer or, where appropriate, the sum of the thicknesses of the silver layers is preferably between 2 and 50 nm, in particular between 3 and 40 nm.

According to another preferred embodiment, the stack of thin layers comprises at least one layer of indium tin oxide. Its physical thickness is preferably between 30 and 200 nm, in particular between 40 and 150 nm.

In order to protect the or each electroconductive thin layer (whether metallic or based on transparent conductive oxide) during the bending step, each of these layers is preferably framed by at least two dielectric layers. The dielectric layers are preferably based on oxide, nitride and/or oxynitride of at least one element chosen from silicon, aluminum, titanium, zinc, zirconium and tin.

At least part of the stack of thin layers can be deposited by various known techniques, for example by chemical vapor deposition (CVD), or by cathode sputtering, in particular assisted by a magnetic field (magnetron process).

The stack of thin layers is preferably deposited by sputtering, in particular assisted by magnetic field. In this process, a plasma is created under a high vacuum in the vicinity of a target comprising the chemical elements to be deposited. The active species of the plasma, by bombarding the target, tear off said elements, which are deposited on the glass sheet, forming the desired thin layer. This process is called "reactive" when the layer is made of a material resulting from a chemical reaction between the elements torn from the target and the gas contained in the plasma. The major advantage of this process lies in the possibility of depositing on the same line a very complex stack of layers by successively scrolling the glass sheet under different targets, generally in a single device.

The aforementioned stacks have electricity conduction and infrared reflection properties that are useful for providing a heating function (defrosting, demisting) and/or a thermal insulation function.

When the stack of thin layers is intended to provide a heating function, current leads must be provided. It may in particular be strips of silver paste deposited by screen printing on the stack of thin layers, at the level of two opposite edges of the glass sheet.

Transparent mineral coatings make it possible to locally modify the optical properties of the glazing in order to create a decoration. Mineral coatings preferably confer a colored appearance, the coloring possibly coming from interference phenomena or from a color in transmission of the layer, due for example to the presence of coloring species. In the case of interference, the coloration may only be seen at certain viewing angles, for example at wide angles.

According to the invention, the first sheet of glass has a face coated with at least two transparent mineral coatings forming a decoration, which are identical or different, said at least two mineral coatings being superposed in at least one zone of said coated face.

In some areas, the decoration may include several superimposed layers of a transparent mineral coating of the same type. Alternatively, the decor can be formed from a plurality of transparent mineral coatings of different natures, superimposed in certain areas.

The at least two transparent mineral coatings can be exactly superimposed, in the sense that there is no zone of the glazing coated by a single transparent mineral coating. Alternatively, the at least two transparent mineral coatings may only be partially superimposed. In this case, certain areas of the glazing may only be coated with a single transparent mineral coating.

It was observed that in the superposition zones, the optical effect obtained, in particular the color, was different from that obtained in the zones where a single mineral coating is deposited. It is thus possible, by depositing successively and possibly locally, two coatings, or even three, four or more, to obtain very varied decorations.

For example, the decoration may comprise a first zone formed solely of a first transparent mineral coating, a second zone formed solely of a second transparent mineral coating, different from the first, and a third zone formed by the superposition of the first coating and the second coating.

The light transmission factor of each transparent coating is preferably between 40 and 95%, in particular between 50 and 80%.

The choice of such a transmission makes it possible not to significantly reduce the brightness inside the passenger compartment, the decor remaining however clearly visible from the outside.

The transparent mineral coating can have anti-reflective properties, by having a lower refractive index than glass. In this case, the decoration will be obtained by superimposing this coating with another transparent mineral coating.

The physical thickness of each transparent mineral coating forming a decoration is preferably between 20 and 250 nm, in particular between 50 and 200 nm, or even between 100 and 150 nm. This is the thickness in the final product, i.e. after a possible baking or sintering step. In some cases, especially when the optical effects are obtained thanks to interference effects, the choice of the thickness makes it possible to adjust the shade obtained.

Each transparent mineral coating is preferably oxide based. Such coatings have the advantage of not degrading any interposed low-emissivity coating and in particular of not affecting its emissivity properties too much.

The oxide is preferably chosen from the group formed by titanium oxides, silicon oxides, zirconium oxides, tin oxides, zinc oxides, aluminum oxides, indium oxides and transition metal oxides. The transition metals are in particular copper, iron, cobalt, chromium and manganese.

The transparent mineral coating may have a colored appearance due to the presence of coloring species, such as pigments or metallic particles, for example gold.

Each transparent oxide-based mineral coating is advantageously a sol-gel coating, that is to say a coating obtained by a sol-gel process.

A sol-gel process typically includes:
- the formation of a "sol", that is to say a solution containing at least one precursor of the oxide to be deposited,
- the application of this solution on the surface to be coated,
- the consolidation or densification of the coating by means of a heat treatment.

The precursor notably comprises salts of the element whose oxide is to be deposited. These include organometallic compounds or even nitrates, acetates, chlorides, etc. Examples of organometallic compounds include alkoxides, for example tetraorthosilicate (TEOS) in the case of a layer of silicon oxide or titanium tetraisopropoxide in the case of a layer of titanium oxide.

The soil may be partially watery. It preferably comprises an organic solvent, for example an alcohol, chosen in particular from ethanol, isopropanol, butanol and glycols or derivatives of glycols, and mixtures thereof. The sol may additionally contain viscosity-regulating agents, such as cellulose ethers or polyacrylates.

Preferably, each transparent mineral coating is oxide-based and each deposition step includes screen printing or digital printing of a precursor of this oxide, in particular of a sol. The digital printing technique is for example an inkjet type technique.

In the case of screen printing, a screen printing screen is placed on the first sheet of glass, which comprises meshes, some of which are closed off, then the composition, in particular the ground, is deposited on the screen, then a doctor blade is applied in order to to force the soil to cross the screen in the zones where the meshes of the screen are not closed, so as to form a moist soil-gel layer.

After deposition, the wet coating is preferably dried in order to eliminate the solvent, in particular at a temperature ranging from 100 to 200°C. A drying step is preferably carried out after each deposition.

In some cases, all of the transparent mineral coatings can then undergo a pre-baking treatment, in particular at a temperature ranging from 550 to 650°C. This treatment is particularly useful in the case of additional steps before bending, for example an assembly step with an additional sheet of glass with a view to manufacturing laminated glazing, or even a step of depositing a opaque layer, in particular on the face opposite the face coated with the transparent mineral coating, requiring conveying on the latter face.

After the deposition of the transparent mineral coating, the first sheet of glass, and if necessary the additional sheet of glass, is preferably bent.

When at least one transparent mineral coating is a sol-gel layer, bending can lead to the densification and consolidation of this layer.

The bending can in particular be carried out by gravity (the glass deforming under its own weight) or by pressing, at temperatures typically ranging from 550 to 650°C. According to a first embodiment, the two sheets of glass (first sheet of glass and additional sheet of glass) are bent separately. According to a second embodiment, the first sheet of glass and the additional sheet of glass are bent together.

The lamination step can be carried out by treatment in an autoclave, for example at temperatures of 110 to 160° C. and under a pressure ranging from 10 to 15 bars. Prior to the autoclave treatment, the air trapped between the glass sheets and the lamination insert can be eliminated by calendering or by depression.

The additional glass sheet can be made of silico-soda-lime glass, or even of borosilicate or aluminosilicate glass. It can be clear or tinted glass. Its thickness is preferably between 0.5 and 4 mm, in particular between 1 and 3 mm.

The lamination interlayer preferably comprises at least one sheet of polyvinylacetal, in particular of polyvinylbutyral (PVB). It advantageously consists of such sheets. In particular, the lamination interlayer does not normally comprise an active layer based on liquid crystals.

The lamination insert can be tinted or untinted in order to regulate the optical or thermal properties of the glazing if necessary. The lamination insert can advantageously have sound absorption properties in order to absorb sounds of aerial or solid-borne origin. It may in particular consist for this purpose of three polymeric sheets, including two so-called outer PVB sheets framing an inner polymeric sheet, optionally made of PVB, of lower hardness than that of the outer sheets.

The lamination insert can also have thermal insulation properties, in particular for reflecting infrared radiation. It may for this purpose comprise a coating of thin layers with low emissivity, for example a coating comprising a thin layer of silver or an alternating coating of dielectric layers of different refractive indices, deposited on an internal PET sheet flanked by two external PVB sheets.

The thickness of the lamination insert is generally within a range ranging from 0.3 to 1.5 mm, in particular from 0.5 to 1 mm. The lamination insert may have a lower thickness on one edge of the glazing than in the center of the glazing in order to avoid the formation of a double image when using a head-up vision system, known as HUD ( head-up display).

Examples

The following examples illustrate the invention in a non-limiting manner, in connection with the .

represents an example of glazing 1 according to the invention.

represents another example of glazing 10 according to the invention.

Glazing 1 is a motor vehicle rear quarter panel formed of a sheet of glass 2 of green-tinted silico-soda-lime glass, 3.85 mm thick. The light transmission factor of the glass sheet 2 is 60%.

The decoration, in the example based on triangles, was then deposited by serigraphy of sol-gel solutions, forming two superimposed coatings 4. To do this, two successive prints were made from solutions marketed by the company Ferro under the reference TLU0050, with a wet thickness of 14 μm for each coating and intermediate drying (150° C., 2 minutes).

The glass sheet 2 was then bent and tempered at 650° C. for 180 seconds. The decor has a golden reflection visible from outside the vehicle.

The glazing 10 is a motor vehicle rear window made of a glass sheet 2 of a green-tinted soda-lime silicate glass, with a thickness of 3.85 mm. The light transmission factor of the glass sheet 2 is 40%.

A decoration was formed on the glass sheet 2 by successive steps of screen printing the same sol-gel solution (Ferro TLU0050). In zone 22, a single coating 12 has been deposited. In zone 24, two coatings 12 have been superimposed. In zone 26, three coatings 12 have been superimposed. In zone 28, four coatings 12 have been superimposed. Between two successive deposition steps, intermediate drying (150° C., 2 minutes) was carried out. The wet thickness of each coating was 14 µm. After quenching and bending treatment at 650°C for 180 seconds, the thickness of each coating was about 30-40 nm.

The superposition of the coatings made it possible to create zones with different appearances: zone 22 has a silvery appearance, zone 24 has a golden appearance, zone 26 has a pink-red appearance and zone 28 has a bluish appearance.

Claims (10)

Rear window or quarter panel of a motor vehicle (1, 10) comprising a first sheet of glass (2), the face of which intended to be located on the exterior side of the vehicle is coated on at least a part of the latter with at least two transparent mineral coating (4, 12) forming a decor, identical or different, said at least two mineral coatings being superimposed in at least one zone (24, 26, 28) of said outer face. Rear window or quarter panel of a motor vehicle (1, 10) according to claim 1, further comprising an additional sheet of glass adhesively bonded to the first sheet of glass (2) by means of an interlayer of thermoplastic lamination, in particular based on polyvinylacetal. Motor vehicle rear window or quarter panel (1, 10) according to one of the preceding claims, in which a low-emissivity coating is interposed between the first sheet of glass (2) and the transparent mineral coatings (4, 12). Motor vehicle rear window or quarter panel (1, 10) according to one of the preceding claims, in which the light transmission factor of each transparent mineral coating (4, 12) is between 40 and 95%, in particular between 50 and 80 %. Motor vehicle rear window or quarter panel (1, 10) according to one of the preceding claims, in which the physical thickness of each transparent mineral coating (4, 12) forming a decoration is between 20 and 250 nm, in particular between 50 and 200nm. Motor vehicle rear window or quarter panel (1, 10) according to one of the preceding claims, in which each transparent mineral coating (4, 12) is oxide-based. Motor vehicle rear window or quarter panel (1, 10) according to the preceding claim, in which each transparent mineral coating (4, 12) is a sol-gel coating. Motor vehicle rear window or quarter panel (1, 10) according to the preceding claim, in which the oxide is chosen from the group formed by titanium oxides, silicon oxides, zirconium oxides, tin oxides, zinc oxides, aluminum oxides, indium oxides and transition metal oxides. Process for obtaining a motor vehicle rear window or quarter window (1, 10) according to one of the preceding claims, comprising the successive deposition on at least part of one face of a sheet of glass of at least two transparent mineral coatings (4, 12) forming a decoration, identical or different, said at least two mineral coatings being superposed in at least one zone (24, 26, 28) of said outer face. Process according to the preceding claim, in which each transparent mineral coating (4, 12) is oxide-based, each deposition step comprising screen printing or digital printing of a precursor of this oxide, in particular of a sol.