CN115038675A

CN115038675A - Motor vehicle roof comprising a glass sheet

Info

Publication number: CN115038675A
Application number: CN202280002112.3A
Authority: CN
Inventors: K·查本; J·杰玛特; F·弗拉玛里-梅斯波利
Original assignee: Saint Gobain Glass France SAS
Current assignee: Saint Gobain Glass France SAS
Priority date: 2021-01-05
Filing date: 2022-01-03
Publication date: 2022-09-09
Also published as: FR3118626B1; EP4274817A1; WO2022148923A1; FR3118626A1

Abstract

The invention relates to a motor vehicle roof (1) comprising a first glass sheet (2) having an optical transmission coefficient of between 2% and 30%, said first glass sheet having at least one face coated on only a portion thereof with at least one transparent mineral coating (10,12,14) forming a decoration.

Description

Motor vehicle roof comprising a glass sheet

The present invention relates to the field of motor vehicle roofs comprising glass sheets.

More and more motor vehicles are equipped with glass-based roofs. These roofs can increase the brightness of the passenger compartment and give the vehicle an attractive design, especially when viewed from the outside. The thermal performance of the roof must also be optimized to prevent overheating of the passenger compartment, which would require increased air conditioning costs in the summer and thus increased vehicle consumption.

The object of the invention is to propose a motor vehicle roof with an attractive trim, in particular a trim which is visible only from the interior of the vehicle or only from the outside.

To this end, the subject of the invention is a motor vehicle roof comprising a first glass sheet having an optical transmission coefficient of between 2 and 30%, said first glass sheet having at least one face coated on only a portion thereof with at least one decorative-forming transparent mineral coating.

Another subject of the invention is a method for obtaining such a motor vehicle roof, comprising the step of depositing at least one decorative-forming transparent mineral coating on only part of the surface of a first glass sheet having an optical transmission coefficient of between 2 and 30%.

The presence of at least one transparent mineral coating forming a decoration on a very dark glass sheet makes it possible to impart unusual optical properties without impairing the light and thermal comfort of the vehicle occupants. More particularly, the decoration may be visible by an occupant of the vehicle or a person outside the vehicle, with good contrast, as the case may be.

The roof according to the invention is preferably curved to match the curvature of the vehicle. Thus, a distinction is made between a roof inner panel (which is concave) intended to be located on the vehicle inside and a roof outer panel (which is convex) intended to be located on the vehicle outside.

According to a first embodiment, the vehicle roof is laminated, i.e. it further comprises an additional glass sheet adhesively connected to the first glass sheet by means of a thermoplastic laminating interlayer (in particular based on polyvinyl acetal). In this case, each of the glass sheets has an interior face facing the vehicle interior and an exterior face facing the vehicle exterior.

In this embodiment, the first glass sheet is preferably intended to be located on the inside of the vehicle. The face of the first glass sheet coated with the at least one transparent mineral coating is then preferably intended to be located on the inside of the vehicle. This face is commonly referred to in the art as "face 4". Thus, the trim is visible to passengers in the passenger compartment, but not to persons outside the vehicle.

Alternatively, the first glass sheet may be intended to be located on the outside of the vehicle. The face of the first glass sheet coated with the at least one transparent mineral coating is then preferably intended to be located on the outside of the vehicle, in other words at "face 1". In this case, the trim is only visible from outside the vehicle and therefore not visible to the passengers in the passenger compartment.

According to a second embodiment, the roof is monolithic, i.e. it comprises only a single glass sheet, in this case the first glass sheet. In this case, the first glass sheet is generally made of tempered glass in order to meet regulatory requirements in terms of safety. Similarly to what has been described in the case of a laminated roof, the face coated with a transparent mineral coating may be face 1 (intended to be located outside the vehicle) or face 2 (intended to be located inside the vehicle), depending on whether the decoration must be visible from the outside or only from the inside.

The first glass sheet may be flat carbon or curved. The first glass sheet is typically flat upon coating deposition and subsequently bent.

The glass of the first glass sheet is typically soda-lime-silica glass, but other glasses, such as borosilicate or aluminosilicate glasses, may also be used. The first glass sheet is preferably obtained by the float process, i.e. by pouring molten glass onto a bath of molten tin.

The first glass sheet is made of colored glass.

Choosing a light transmission coefficient of 2-30%, in particular 5-20%, may ensure good contrast and thus good visibility of the decoration, but only on the side on which it is deposited.

For this purpose, the glass preferably comprises the following colouring elements, the contents by weight of which are defined below: fe ₂ O ₃ 1.2-2.3%, in particular 1.5-2.2% (total iron), CoO 50-400ppm, in particular 200-350ppm, Se 0-35ppm, in particular 10-30 ppm. The degree of redox is preferably between 0.1 and 0.4, in particular between 0.2 and 0.3. The redox is the ferrous iron content (expressed as FeO) and the total iron content (expressed as Fe) ₂ O ₃ Expressed) in terms of weight.

Herein, the light transmission coefficient is expressed by considering the light source D65 and the CIE-1931 standard observer. The light transmission coefficient of the glass sheets is of course measured without any coating.

The first glass sheet preferably has a thickness in the range of 0.7-19mm, in particular 1-10mm, in particular 2-6mm, or even 2-4 mm.

The transverse dimensions of the first glass sheet (and, if necessary, of the additional glass sheets) will be adjusted according to the transverse dimensions of the laminated glazing in which it is intended to be integrated. The first glass sheet (and/or the additional glass sheet) preferably has at least 1m ² Surface area of (a).

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

The first glass sheet or the additional glass sheet is preferably coated with an opaque layer, in particular made of enamel, usually black enamel, in particular arranged at the periphery of the sheets, for example in the form of a peripheral band. The purpose of such layers is generally to conceal and protect the polymeric seal used to mount the vehicle roof in the vehicle body window opening from ultraviolet radiation.

The opaque layer is preferably deposited by screen printing.

In the case of a laminated roof, the opaque layer is preferably deposited on the additional glass sheet. For example, if a transparent mineral coating is deposited on face 4 of the laminated roof, an opaque layer is preferably deposited on face 2.

When the opaque layer and the transparent mineral coating are deposited on the first glass sheet, they may be deposited on the same face or on two opposite faces. The order of deposition of the two coatings is not critical, but when they are deposited on the same face, it is preferable to deposit the transparent mineral coating first and then the opaque layer, as explained in more detail in the remainder of the text.

According to a preferred embodiment, a coating having a low emissivity is placed between the first glass sheet and the transparent mineral coating. The normal emissivity of the coating, measured at ambient temperature, is preferably below 0.50, in particular below 0.30, even below 0.20 or below 0.10.

The refractive index of the coating and, if necessary, its colour, affect the final appearance of the roof.

The coating with low emissivity is preferably a thin layer stack.

The thin-layer stack is preferably in contact with the first glass sheet. It preferably covers all or at least 90% of the surface area of the first glass sheet.

Herein, "contacting" means physically contacting. The expression "based on" preferably means that the layer in question comprises at least 50% by weight, in particular 60% by weight, even 70% by weight, even 80% by weight or 90% by weight of the material in question. The layer may even consist essentially of or consist of such a material. "consisting essentially of" is understood to mean that the layer may contain impurities which have no effect on its properties. The term "oxide" or "nitride" does not necessarily mean that the oxide or nitride is stoichiometric. In practice, they may be substoichiometric, superstoichiometric or stoichiometric.

The stack preferably comprises at least one nitride based layer. The nitride is in particular a nitride of at least one element selected from the group consisting of aluminum, silicon, zirconium, titanium. It may comprise a nitride of at least two or three of these elements, for example zirconium silicon nitride or silicon aluminum nitride. Preferably, the nitride based layer is a silicon nitride based layer, more particularly a layer consisting essentially of silicon nitride. When the silicon nitride layer is deposited by cathodic sputtering, it typically comprises aluminum, since it is common to dope silicon targets with aluminum to accelerate the deposition rate.

The nitride based layer preferably has a physical thickness in the range of 2-100nm, in particular 5-80 nm.

Nitride-based layers are commonly used in many thin-layer stacks, because they have advantageous barrier properties in the sense that they prevent oxidation of other layers present in the stack, in particular of 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 oxide layers or oxynitride layers.

The at least one electrically conductive functional layer is advantageously selected from:

a metal layer, in particular made of silver or niobium, even gold, and

a transparent conductive oxide layer, in particular chosen from indium tin oxide, doped tin oxide (for example doped with fluorine or antimony), doped zinc oxide (for example doped with aluminium or gallium).

These layers are particularly appreciated for their low emissivity, which provides excellent thermal insulation properties to the glazing. Among the glazings of motor vehicles, the low emissivity glazings allow a portion of the solar radiation to be reflected outwards in hot weather, thus limiting the heating of the passenger compartment of said vehicle and reducing the air conditioning costs if necessary. In contrast, in cold weather, these glazings allow heat to be retained within the passenger compartment, thereby reducing the heating energy required. This is the same in the case of glazing for buildings.

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

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

In order to protect the or each conductive thin layer (whether it be metallic or based on a transparent conductive oxide) during the bending step, each of these layers is preferably surrounded by at least two dielectric layers. The dielectric layer is preferably based on an oxide, nitride and/or oxynitride of at least one element selected from the group consisting of silicon, aluminum, titanium, zinc, zirconium and tin.

At least a portion of the stack of thin layers may be deposited by various known techniques, such as Chemical Vapor Deposition (CVD), or by cathode sputtering, in particular magnetic field assisted cathode sputtering (magnetron method).

The stack of thin layers is preferably deposited by cathodic sputtering, in particular magnetic field assisted cathodic sputtering. In this method, plasma is generated under high vacuum in the vicinity of a target containing a chemical element to be deposited. By bombarding the target, the active species of the plasma tear off the elements, which are deposited on the glass sheet, forming the desired thin layer. When the layer is composed of a material resulting from a chemical reaction between an element torn from the target and a gas contained in the plasma, the method is referred to as a "reactive" method. The main advantage of this method is that very complex stacks of layers can be deposited on the same production line by running the glass sheets in succession under different targets (usually in the same apparatus).

The above-mentioned stack has electrically conductive and infrared-reflective properties for providing a heating function (defrosting, defogging) and/or a thermal insulation function.

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

The transparent mineral coating allows the optical properties of the roof to be locally modified to create a decoration. The mineral coating preferably imparts a coloured appearance, which may, as the case may be, originate from interference phenomena or from the transmitted colour of the layer, for example due to the presence of colouring substances. In the case of interference, the coloration can only be seen at certain viewing angles, for example at large angles.

The decoration may be formed by a single transparent mineral coating. In some areas, the decoration may comprise a plurality of transparent mineral coatings of the same substance in superimposed thickness. Alternatively, the decoration may be formed by a plurality of transparent mineral coatings of different substances (optionally superimposed in some areas).

According to one embodiment, the first glass sheet has a face coated with at least two identical or different decorative-forming transparent mineral coatings, said at least two mineral coatings being superimposed in at least one region of the coated face. It has been observed that in the superimposed zones, the optical effects, in particular the colours, obtained are different from those obtained in the zones in which the single mineral coating is deposited. Thus, by continuously and optionally locally depositing two coatings, even three, four or more coatings, a highly variable decoration can be obtained.

For example, the decor may include a first region formed only of a first transparent mineral coating, a second region formed only of a second transparent mineral coating different from the first transparent mineral coating, and a third region formed by superimposing the first coating and the second coating.

The optical transmission coefficient of the or each transparent coating when deposited on clear glass is preferably in the range 40 to 95%, in particular 50 to 80%. The clear glass contains 0.05-0.1% total iron (as Fe) ₂ O ₃ Formal representation) having an optical transmission coefficient of about 90%. Such glasses are sold in particular under the designation Planilear, Planibel Clear or Optifloat Clear.

The transparent mineral coating may have anti-reflective properties (due to having a lower refractive index than that of glass). In this case, the decoration will generally be obtained by superimposing this coating with another transparent mineral coating.

The choice of such light transmission may not significantly reduce the brightness within the passenger compartment, but the decoration is still clearly visible.

The physical thickness of the or each transparent mineral coating forming the decoration is preferably 20-250nm, in particular 50-200nm, or even 100-150 nm. Here, this is the thickness in the final product, thus after an optional curing or sintering step. In some cases, in particular when the optical effect is obtained by an interference effect, the choice of thickness allows to adjust the hue obtained.

The or each transparent mineral coating is preferably oxide based. Such a coating has the advantage of not degrading the optional interposed low-emissivity coating, in particular not unduly affecting its emissivity properties.

The oxide is preferably selected from the group consisting of titanium oxide, silicon oxide, zirconium oxide, tin oxide, zinc oxide, aluminum oxide, indium oxide, 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 substances, such as pigments or metal particles, such as gold particles.

The or each oxide-based transparent mineral coating is advantageously a sol-gel coating. I.e. a coating obtained by a sol-gel process.

Sol-gel processes generally comprise:

-forming a "sol", i.e. a solution containing at least one oxide precursor to be deposited,

applying the solution to the surface to be coated,

consolidation or densification of the coating by heat treatment.

The precursor comprises in particular salts of the elements whose oxides are intended to be deposited. It is in particular an organometallic compound or a nitrate, acetate, chloride, etc. As examples of organometallic compounds, mention may be made, for example, of alkoxides, such as Tetraorthosilicate (TEOS) in the case of a silicon oxide layer, or titanium tetraisopropoxide in the case of a titanium oxide layer.

The sol may be partially aqueous. It preferably comprises an organic solvent, for example an alcohol, in particular selected from ethanol, isopropanol, butanol and a diol or diol derivative, and mixtures thereof. The sol may also comprise a viscosity modifier, such as a cellulose ether or a polyacrylate.

Preferably, the or each transparent mineral coating is oxide-based and the deposition step comprises screen printing or digital printing of a precursor of the oxide, in particular a sol.

In the case of screen printing, a screen-printing screen comprising holes, some of which are blocked, is placed on the first glass sheet, then a composition, in particular a sol, is deposited on the screen, and then a doctor blade is applied to force the sol through the screen in the areas where the holes of the screen are not blocked, to form a wet sol-gel layer.

After deposition, the wet coating is preferably dried to remove the solvent, in particular at a temperature of from 100 to 200 ℃.

When multiple transparent mineral coatings are deposited in succession, a drying step is typically performed after each deposition.

In some cases, the transparent mineral coating (or all of these coatings) may be subsequently subjected to a pre-curing treatment, particularly at a temperature of 550-. This treatment is particularly useful in the case of an additional step before bending (for example a step of assembly with an additional sheet of glass to make a laminated roof, or a step of deposition of an opaque layer), in particular on the side opposite to the side coated with the transparent mineral coating, requiring transport on the side coated with the transparent mineral coating.

For example, the method may comprise depositing a transparent mineral coating on one part of the face of a first glass sheet, then drying and pre-curing, then conveying on that face, then depositing an opaque layer, in particular an enamel layer, on the other face, then bending, in the case of a monolithic roof, or, in the case of a laminated roof, a second pre-curing, assembling with an additional glass sheet, bending the two glass sheets together, and finally laminating.

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

When the transparent mineral coating is a sol-gel layer, the bending may result in densification and consolidation of the layer.

Bending can be carried out using gravity (the glass deforms under its own weight) or by pressing at temperatures typically 550 to 650 ℃.

According to a first embodiment, the two glass sheets (the first glass sheet and the additional glass sheet) are bent separately. According to a second embodiment, the first glass sheet and the additional glass sheet are bent together.

The lamination step may be carried out by treatment in an autoclave, for example at a temperature of 110 to 160 ℃ and a pressure of 10 to 15 bar. Prior to autoclaving, air trapped between the glass sheet and the laminate interlayer can be eliminated by calendering or by applying negative pressure.

The additional glass sheets may be made of soda-lime-silica glass, or of borosilicate or aluminosilicate glass. It may be made of clear or colored glass. Its thickness is preferably between 0.5 and 4mm, in particular between 1 and 3 mm.

The lamination interlayer preferably comprises at least one polyvinyl acetal sheet, in particular a polyvinyl butyral (PVB) sheet. It is advantageously composed of such a sheet. In particular, the lamination interlayer typically does not include a liquid crystal-based active layer.

The lamination interlayer may be tinted or non-tinted, if desired, to modify the optical or thermal properties of the glazing.

The laminated interlayer may advantageously have sound absorbing properties in order to absorb sound of air origin or of solid origin. To this end, it may in particular consist of three polymeric sheets, including two "outer" PVB sheets, optionally made of PVB, surrounding an inner polymeric sheet, the hardness of which is lower than that of the outer sheets.

The laminated interlayer may also have thermal insulating properties, in particular infrared radiation reflecting properties. To this end, it may comprise a thin layer coating with low emissivity, for example a coating comprising a thin silver layer or a coating with alternating dielectric layers of different refractive index, deposited on an inner PET sheet surrounded by two outer PVB sheets.

The thickness of the laminated intermediate layer is generally in the range of 0.3 to 1.5mm, in particular 0.5 to 1 mm. The thickness of the laminated interlayer may be less at the edges of the glazing than at the centre of the glazing to prevent double images from being formed in the case of a heads up display system (known as a "HUD").

Examples

The following examples illustrate the invention in a non-limiting manner in conjunction with FIG. 1.

Fig. 1 shows an example of a vehicle roof 1 according to the invention.

The roof 1 is formed from a glass sheet 2 of soda-lime-silica glass having a thickness of 3.85mm with a dark grey tone. The optical transmission coefficient of the glass sheet 2 was 10%. On this glass sheet 2 a low emissivity coating (standard emissivity 0.30) comprising a thin layer of ITO is deposited, which is not shown.

The decoration is then deposited by screen printing a sol-gel solution. Strip 10 is deposited first (Ferro TLU0050), then strip 12 (also Ferro TLU0050) and finally L-shaped strip 14(Ferro TLU 0055). The three strips are partially superimposed to form areas with different appearances.

Drying at 160 ℃ was carried out after each deposition step.

The glass sheet 2 is then bent and laminated together with additional glass sheets so that the decoration is located on the face 4 of the laminated roof.

In the area 20, where only the

coating

10 or 12 is applied, the appearance is silver. In the region 24 coated with only the coating 14, the appearance is gold. In the region 22 coated with the superimposed

coatings

10 and 12, the appearance is also golden. In the areas 26 coated with the over-coatings 12 and 14, the appearance is turquoise blue. Finally, in the areas 28 coated with the superimposed

coatings

10,12 and 14, the appearance is emerald green.

The emissivity of the low emissivity coating is unaffected by the presence of the decoration because it remains at 0.30 or 0.31 in the areas coated with the decoration.

However, in the comparative example in which the decoration is obtained by depositing enamel, the emissivity is severely reduced, having a value of about 0.8.

Claims

1. A motor vehicle roof (1) comprising a first glass sheet (2) having an optical transmission coefficient of between 2% and 30%, said first glass sheet having at least one face coated on only a portion thereof with at least one decorative-forming transparent mineral coating (10,12, 14).

2. The vehicle roof (1) according to claim 1, further comprising an additional glass sheet which is adhesively connected to the first glass sheet (2) by a thermoplastic lamination interlayer, in particular a polyvinyl acetal-based thermoplastic lamination interlayer.

3. Vehicle roof (1) according to the preceding claim, wherein the first glass sheet (2) is intended to be located on the inside of the vehicle.

4. Roof (1) according to any of the preceding claims, wherein the face of the first glass sheet (2) coated with the at least one transparent mineral coating (10,12,14) is intended to be located on the inside of a vehicle.

5. Roof (1) according to any of the preceding claims, wherein the first glass sheet (2) has an optical transmission coefficient of 5-20%.

6. Roof (1) according to any of the preceding claims, wherein the first glass sheet (2) or, if necessary, an additional glass sheet, is coated with an opaque layer, in particular a black enamel opaque layer, which is arranged in the form of a peripheral strip at its periphery.

7. Vehicle roof (1) according to any of the preceding claims, wherein a coating with low emissivity is sandwiched between the first glass sheet (2) and the transparent mineral coating (10,12, 14).

8. Roof (1) according to any of the preceding claims, wherein the first glass sheet (2) has a face coated with at least two decoratively forming transparent mineral coatings (10,12,14) of the same or different, which are superimposed in at least one area (22, 26, 28) of the coated face.

9. Vehicle roof (1) according to any one of the preceding claims, wherein the or each transparent coating layer has an optical transmission coefficient of 40-95%, in particular 50-80%, when deposited on clear glass.

10. Vehicle roof (1) according to any of the preceding claims, wherein the physical thickness of the or each transparent mineral coating (10,12,14) forming the trim is 20-250nm, in particular 50-200 nm.

11. Vehicle roof (1) according to any of the preceding claims, wherein the or each transparent mineral coating (10,12,14) is oxide-based.

12. Vehicle roof (1) according to the preceding claim, wherein the or each transparent mineral coating (10,12,14) is a sol-gel coating.

13. Vehicle roof (1) according to one of the claims 11 or 12, wherein the oxide is selected from the group consisting of titanium oxide, silicon oxide, zirconium oxide, tin oxide, zinc oxide, aluminum oxide, indium oxide and transition metal oxides.

14. Method for obtaining a motor vehicle roof (1) according to any one of the preceding claims, comprising the step of depositing at least one decorative forming transparent mineral coating (10,12,14) on only a portion of a face of a first glass sheet (2), the first glass sheet (2) having an optical transmission coefficient of between 2 and 30%.

15. The method according to the preceding claim, wherein the or each transparent mineral coating (10,12,14) is based on an oxide, the deposition step comprising screen printing or digital printing of a precursor, in particular a sol, of such an oxide.