Motor vehicle corner glazing comprising a sheet of glass

Abstract

The invention relates to a motor vehicle corner glazing comprising a first glazing intended for the exterior of the vehicle, characterised in that the face of said first glazing intended for the exterior of the vehicle, referred to as face 1 , is coated only on a portion thereof with at least one reflective and transparent mineral coating forming a decoration.

Description

[0001] The present invention relates to the field of corner glazings for motor vehicles comprising a sheet of glass.

[0002] The object of the present invention is to provide a motor vehicle corner window having an attractive decoration, in particular a decoration that is largely visible from the outside of the vehicle.

[0003] To this end, the subject of the invention is a motor vehicle corner glazing comprising a first sheet of glass intended to be located on the outside of the vehicle, characterized in that the face of said first sheet of glass intended to be located on the outside of the vehicle, referred to as face 1 , is coated only on a portion thereof with at least one reflective and transparent mineral coating forming a decoration.

[0004] Another subject of the invention is a method for obtaining such a corner glazing unit for a motor vehicle, comprising a step of depositing at least one reflective and transparent mineral coating forming a decoration on only a portion of a first glass sheet. The invention also relates to a motor vehicle comprising at least one such corner glazing unit, and in particular two such corner glazing units.

[0005] A mineral coating is considered reflective and transparent because it reflects some light and transmits some light (within the visible range). Therefore, it is not fully reflective (which would make it opaque), nor is it completely transparent. In the rest of this article, a reflective and transparent mineral coating is sometimes referred to simply as a "mineral coating."

[0006] The presence of at least one reflective and transparent mineral coating forming a decoration on face 1 of the glass sheet makes it possible to impart unusual optical properties without having a detrimental effect on the light and thermal comfort of the vehicle's occupants. More specifically, the decoration can be made visible by reflection with good contrast to people outside the vehicle, while remaining virtually invisible to the vehicle's occupants, in particular at grazing incidence.

[0007] The corner glazing according to the invention is preferably curved so as to match the curvature of the body of the vehicle in which it is embedded.

[0008] Thus, a distinction is made between the inner face of the corner glazing, which is intended to be located on the inside of the vehicle and is concave, and the outer face of the corner glazing, which is intended to be located on the outside of the vehicle and is convex.

[0009] According to a first embodiment, the corner glazing is laminated, i.e., it further comprises an additional glass sheet intended to be located on the inside of the vehicle, adhesively bonded to the first glass sheet by means of a thermoplastic laminating interlayer, in particular based on polyvinyl acetal. In this case, each glass sheet has an inner face facing the vehicle interior and an outer face facing the vehicle exterior.

[0010] According to a second embodiment, the corner glazing is monolithic, ie it comprises only a single glass sheet, in this case a first glass sheet. In this case, the first glass sheet is usually made of tempered glass in order to meet regulatory requirements in terms of safety.

[0011] The first glass sheet may be flat or curved.The first glass sheet is typically flat when the mineral coating is deposited and is subsequently curved.

[0012] The glass of the first glass sheet is typically soda-lime-silica glass, but other glasses, such as borosilicate or aluminosilicate, 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. Alternatively, the first glass sheet may be made of printed glass and thus have a surface texture, typically obtained by passing the glass between rollers.

[0013] The first glass sheet is preferably made of colored glass.The light transmittance of the first glass sheet is preferably between 2% and 50%, in particular between 8% and 45%, or even between 20% and 40%.

[0014] The lower light transmittance makes it possible to ensure good contrast of the decoration and therefore good visibility of the decoration, but only on the side on which it is deposited.

[0015] According to one embodiment, the glass contains iron oxide (expressed as Fe2O3 (total iron)) as a coloring component in a proportion of 0.5-1.2%, in particular 0.6-1.1%. The redox ratio is preferably between 0.1 and 0.4, in particular between 0.2 and 0.3. The redox ratio is the weight ratio of the ferrous content (expressed as FeO) to the total iron content (expressed as Fe2O3).

[0016] To achieve a lower light transmittance, the glass preferably contains the following coloring elements, the contents of which are defined as follows by weight: Fe2O3 (total iron) 1.2-2.3%, in particular 1.5-2.2%, CoO 50-400 ppm, in particular 200-350 ppm, Se 0-35 ppm, in particular 10-30 ppm. The redox ratio is preferably between 0.1 and 0.4, in particular between 0.2 and 0.3.

[0017] Herein, light reflectance and light transmittance are expressed using illuminant D65 and the CIE-1964 standard observer. The light transmittance of the glass sheets was measured in the absence of any coating (or in areas without coating). Other measurements (reflection and transmission of corner glazing) were made in the presence of the mineral coating, and therefore in areas where the coating was present. Unless otherwise specified, these parameters were measured at normal incidence.

[0018] The first glass sheet preferably has a thickness comprised within the range of 0.7 to 19 mm, in particular 1 to 10 mm, in particular 2 to 6 mm, or even 2 to 4 mm.

[0019] The lateral dimensions of the first glass sheet (and, where appropriate, the additional glass sheet) will be adjusted based on the lateral dimensions of the laminated glazing with which it is intended to be integrated. The surface area of ​​the first glass sheet (and / or the additional glass sheet) is preferably at least 0.1 m 2 .

[0020] The first glass sheet is preferably coated with a mineral coating over 5% to 90% of the surface area of ​​the glass sheet face, in particular over 10% to 80% of the surface area, depending on the desired decoration.

[0021] The first glass sheet or the additional glass sheet is preferably coated with an opaque layer, particularly made of enamel, typically black enamel, and disposed around its perimeter, for example in the form of a peripheral band. The purpose of this layer is generally to conceal and protect from UV radiation the polymer seal used to mount the corner glazing in the vehicle body window. This opaque layer is preferably deposited by screen printing. In the case of laminated corner glazing, the opaque layer is preferably deposited on the additional glass sheet, particularly on face 3 of the corner glazing. When the opaque layer is deposited on the first glass sheet, it will be deposited on face 2 of the corner glazing.

[0022] According to one embodiment, a low-emissivity coating may be deposited on the face of the first glass sheet opposite the face bearing the reflective and transparent mineral coating, and / or, where appropriate, on one face of the additional glass sheet. The standard emissivity of this coating, measured at ambient temperature, is preferably greater than 0.50, in particular 0.30, and even 0.20 or 0.10.

[0023] The refractive index and, where appropriate, the color of the coating can influence the final appearance of the corner glazing.

[0024] The low-E coating is preferably a stack of thin layers.

[0025] The thin-film stack is preferably in contact with the first glass sheet or with the additional glass sheet. It preferably covers the entire surface or at least 90% of the surface of the glass sheet.

[0026] In this context, "in contact" is intended to mean physical contact. The expression "based on" is preferably intended to indicate that the layer in question comprises at least 50% by weight of the material in question, in particular 60%, or even 70%, and even 80% or 90% by weight of the material in question. A layer may even consist essentially of or consist of this material. "Essentially consisting of" is understood to mean that a layer may contain impurities that have no effect on its properties. The terms "oxide" or "nitride" do not necessarily mean stoichiometric oxides or nitrides. In fact, they can be substoichiometric, superstoichiometric, or stoichiometric.

[0027] The stack preferably includes 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, and titanium. It may also include nitrides of at least two or three of these elements, for example silicon zirconium nitride or silicon aluminum nitride. The nitride-based layer is preferably a silicon nitride-based layer, more particularly a layer consisting essentially of silicon nitride. When the silicon nitride layer is deposited by cathode sputtering, it typically contains aluminum, as it is common practice to dope silicon targets with aluminum to accelerate the deposition rate.

[0028] The nitride-based layer preferably has a physical thickness of 2 to 100 nm, in particular 5 to 80 nm.

[0029] Nitride-based layers are often used for bulk stacks of thin layers, since they have advantageous barrier properties, since they prevent oxidation of the other layers present in the stack, in particular of the functional layers to be described below.

[0030] Preferably, the stack 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 oxide or oxynitride.

[0031] The at least one electrically conductive functional layer is advantageously selected from:

[0032] - a metal layer, in particular a layer of silver, niobium or gold, and

[0033] - a layer of a transparent conductive oxide, in particular chosen from indium tin oxide, doped tin oxide (for example doped with fluorine or antimony), doped zinc oxide (for example doped with aluminum or gallium).

[0034] These layers are particularly valuable due to their low emissivity, which imparts excellent thermal insulation properties to glazing. In the glazing of motor vehicles, low-e glazing allows for the reflection of some of the solar radiation outwards during hot weather, thereby limiting the heating of the vehicle's passenger compartment and, where appropriate, reducing air conditioning costs. Conversely, in cold weather, these glazings allow for the retention of heat within the passenger compartment, thereby reducing the required heating energy. The same applies to the glazing of buildings.

[0035] According to a preferred embodiment, the stack of thin layers comprises at least one silver layer, in particular one, two, three or even four silver layers. The physical thickness of the silver layers, or where appropriate the sum of the thicknesses of the silver layers, is preferably 2-50 nm, in particular 3-40 nm.

[0036] According to another preferred embodiment, the stack of thin layers comprises at least one layer of indium and tin oxides, the physical thickness of which is preferably between 30 and 200 nm, in particular between 40 and 150 nm.

[0037] In order to protect the or each conductive thin layer (whether 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 layers are preferably based on oxides, nitrides and / or oxynitrides of at least one element chosen from silicon, aluminum, titanium, zinc, zirconium and tin.

[0038] At least a part of the thin-layer stack can be deposited by various known techniques, such as chemical vapor deposition (CVD), or by sputtering deposition, in particular with the assistance of a magnetic field (magnetron method).

[0039] The stack of thin layers is preferably deposited by cathode sputtering, in particular magnetron sputtering. In this method, a plasma is generated in a high vacuum near a target containing the chemical element to be deposited. By bombarding the target, the reactive species of the plasma cause the element to flake off, which is deposited on the glass sheet to form the desired thin layer. This method is called a "reactive" method when the layer is produced by a chemical reaction between the element flake off from the target and the gases contained in the plasma. The main advantage of this method is that, by continuously moving the glass sheet under various targets, often in the same equipment, very complex stacks of layers can be deposited on the same production line.

[0040] The above examples have conductive and infrared reflective properties, which have applications for providing heating functions (defrosting, defogging) and / or thermal insulation functions.

[0041] When the stack of thin layers is intended to provide a heating function, an electric current supply must be provided. This can in particular be strips of silver paste deposited by screen printing on the stack of thin layers at two opposite edges of the glass sheet.

[0042] Reflective and transparent mineral coatings make it possible to locally modify the optical properties of corner glazing units to create a decorative effect. The mineral coating preferably imparts a tinted appearance, which may result from (depending on the case) interference phenomena or from the color in transmission or reflection from the layer, for example, due to the presence of a coloring substance. In the case of interference, the tinting is only visible at certain viewing angles, for example, at wide angles.

[0043] The decoration may be formed from a single reflective and transparent mineral coating. In some areas, the decoration may include several overlapping thicknesses of the same mineral coating. Alternatively, the decoration may be formed from multiple mineral coatings of different properties, optionally overlapping in some areas. Preferably, neither the first glass sheet nor the reflective and transparent mineral coating is textured. In the event that the decoration is formed from multiple mineral coatings, none of them is typically textured.

[0044] According to one embodiment, the first glass sheet has a face coated with at least two identical or different reflective and transparent mineral coatings forming a decoration, said at least two mineral coatings being superimposed in at least one region of said coated face. It has been observed that in the superimposed region, the optical effect, in particular the color, obtained differs from that obtained in the region where a single mineral coating was deposited. Thus, by sequentially and optionally locally depositing two coatings, or even three, four, or more coatings, highly variable decorations can be achieved.

[0045] For example, the decoration may include a first area formed only of a first reflective and transparent mineral coating, a second area formed only of a second transparent mineral coating different from the first, and a third area formed by superimposing the first and second coatings.

[0046] The or each reflective and transparent mineral coating is preferably such that, when deposited on clear glass, it has a light transmittance of 40-95%, in particular 50-80%. Clear glass is glass containing 0.05-0.1% total iron (expressed as Fe2O3) and having a light transmittance of approximately 90%. Such glass is sold in particular under the designations Planiclear, Planibel Clear or Optifioat Clear.

[0047] This transmission is chosen so that the brightness in the passenger compartment is not significantly reduced and so that the decoration is not very visible to the vehicle passengers.

[0048] The light reflectivity of the corner glazing is preferably between 15% and 40% when viewed from face 1 at an incident angle of 45° and in the decorative area. The light reflectivity of the corner glazing is preferably between 5% and 10% when viewed from face 2 at an incident angle of 45° and in the decorative area.

[0049] The physical thickness of the or each reflective and transparent mineral coating forming the 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 of the final product, i.e., after the optional curing or sintering step. In some cases, particularly when the optical effect is achieved due to interference effects, the choice of thickness makes it possible to adjust the resulting color tone.

[0050] The or each reflective and transparent mineral coating is preferably based on an oxide. The oxide is preferably selected from titanium oxide, silicon oxide, zirconium oxide, tin oxide, zinc oxide, aluminum oxide, indium oxide and transition metal oxides. Transition metals are in particular copper, iron, cobalt, chromium and manganese.

[0051] The reflective and 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.

[0052] The or each reflective and transparent oxide-based mineral coating is advantageously a sol-gel coating. This is a coating obtained by a sol-gel process.

[0053] The sol-gel method generally includes:

[0054] - forming a "sol", ie a solution containing at least one precursor of the oxide to be deposited,

[0055] - applying the solution to the surface to be coated,

[0056] -Consolidation or densification of the coating by heat treatment.

[0057] Precursors include, in particular, salts of the element whose oxide is to be deposited. These are, in particular, organometallic compounds or nitrates, acetates, chlorides, etc. Examples of organometallic compounds include alkoxides, such as tetraorthosilicate (TEOS) in the case of silicon oxide layers, or titanium tetraisopropoxide in the case of titanium oxide layers.

[0058] The sol may be partially aqueous. It preferably comprises an organic solvent, such as an alcohol, in particular selected from ethanol, isopropanol, butanol and glycols or glycol derivatives, and mixtures thereof. The sol may further contain a viscosity modifier, such as a cellulose ether or a polyacrylate.

[0059] Preferably, the or each reflective and transparent mineral coating is based on an oxide and the deposition step comprises screen printing or digital printing of a precursor of the oxide, in particular a sol.

[0060] In the case of screen printing, a screen printing screen is placed on a first glass sheet, the screen comprising holes, some of which are blocked, and a composition, in particular a sol, is deposited on the screen. A doctor blade is then applied to force the sol through the screen in areas where the screen holes are not blocked, thereby forming a wet sol-gel layer.

[0061] After deposition, the wet coating is preferably dried to remove the solvent, particularly at temperatures between 100 and 200°C.

[0062] When several reflective and transparent mineral coatings are deposited successively, a drying step is usually carried out after each deposition.

[0063] In some cases, the reflective and transparent mineral coating (or all of these coatings) may then be subjected to a pre-curing treatment, in particular at temperatures between 550 and 650° C. This treatment is particularly useful in the case of additional steps prior to bending, such as steps of assembly with additional glass sheets in order to manufacture laminated corner glazings, or steps of depositing an opaque layer, in particular on the face opposite to the face coated with the transparent mineral coating, on which conveying is necessary.

[0064] For example, the method may comprise depositing a reflective and transparent mineral coating on a portion of the face of a first glass sheet, followed by drying and pre-curing, then conveying on that face, then depositing an opaque layer, in particular an enamel, on the other face, then bending, in the case of a monolithic corner glazing, or, in the case of a laminated corner glazing, a second pre-curing, assembly with an additional glass sheet, bending the two glass sheets together, and finally laminating.

[0065] After deposition of the reflective and transparent mineral coating, the first glass sheet and, where appropriate, the additional glass sheets are preferably bent.

[0066] When the reflective and transparent mineral coating is a sol-gel layer, bending can cause densification and consolidation of the layer.

[0067] Bending can be done using gravity, for example (the glass deforms under its own weight) or by pressing, at temperatures typically 550-650°C.

[0068] 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 separately.

[0069] The lamination step can be carried out by treatment in an autoclave, for example at a temperature of 110 to 160° C. and a pressure of 10 to 15 bar. Prior to the autoclave treatment, air trapped between the glass sheet and the laminating interlayer can be eliminated by calendering or by applying negative pressure.

[0070] The additional glass sheet can be made of soda-lime-silica glass, borosilicate glass, or aluminosilicate glass. It can be made of transparent or colored glass. Its thickness is preferably between 0.5 and 4 mm, in particular between 1 and 3 mm.

[0071] The laminating interlayer preferably comprises at least one polyvinyl acetal sheet, in particular polyvinyl butyral (PVB) sheet. It advantageously consists of such a sheet.

[0072] If desired, the laminating interlayer may be tinted or untinted to adjust the optical or thermal properties of the glazing.

[0073] The laminating interlayer may advantageously have sound-damping properties in order to absorb airborne or structure-borne sound. To this end, it may in particular be composed of three polymer sheets, including two "outer" PVB sheets surrounding an inner polymer sheet, the inner polymer sheet optionally being made of PVB having a lower hardness than the outer sheets.

[0074] The laminating interlayer may also have thermal insulation properties, in particular infrared radiation reflecting properties. To this end, it may comprise a coating of a thin layer with low emissivity, for example a coating comprising a thin layer of silver or a coating of alternating dielectric layers with different refractive indices, deposited on an inner PET sheet surrounded by two outer PVB sheets.

[0075] The thickness of the laminating interlayer is generally 0.3-1.5 mm, in particular 0.5-1 mm. Example

[0076] The following examples illustrate the invention in a non-limiting manner.

[0077] The corner glazing is formed of a glass sheet of soda-lime-silica glass having a dark grey tint, 3.15 mm thick, and has a light transmittance of 35%.

[0078] The decoration was deposited by screen printing a sol-gel solution of a titanium dioxide precursor on one side of a glass sheet, followed by drying at 160°C.

[0079] The glass sheet is then tempered so that the decoration is located on face 1 of the corner glazing. After tempering, the physical thickness of the mineral coating is 50-100 nm.

[0080] Table 1 below shows the difference in light reflectance (ΔRL) and reflected color (ΔL*, Δa*, Δb*, ΔE) relative to an uncoated glass sheet of the same properties, as a function of the incident angle (15° to 75°) relative to the normal and observed from surface 1.

[0081] Table 1

[0082] 15° 30° 45° 60° 75° ΔRL(%) 16.98 16.71 16.09 14.45 9.53 ΔL* 26.68 26.18 24.19 18.43 8.05 Δa* -0.56 -0.55 -0.47 -0.33 -0.06 Δb* -8.624 -9.04 -8.71 -6.65 -1.67 ΔE 28.04 27.70 28.60 25.71 8.22

[0083] Thus, from face 1, including at grazing incidence, the decoration is clearly visible in both reflection and color.

[0084] Table 2 below shows the same quantities, but for reflections from face 2 (and therefore from the interior of the vehicle).

[0085] Table 2

[0086] 15° 30° 45° 60° 75° ΔRL(%) 2.31 2.07 1.64 0.94 -0.07 ΔL* 5.57 4.97 3.68 1.61 -0.07 Δa* -4.78 -4.45 3.71 -1.96 -0.17 Δb* -1.02 -1.31 -0.93 -0.35 0.19 ΔE 7.41 6.80 5.31 2.56 0.26

[0087] These values ​​show that the decoration is not very visible in reflection and color from inside the vehicle and is even almost invisible in grazing incidence.

[0088] Table 3 below shows the differences in light transmittance (ΔTL) and transmission color (ΔL*, Δa*, Δb*, ΔE) relative to an uncoated glass sheet of the same properties as a function of the angle of incidence (15° to 75°) relative to the normal.

[0089] Table 3

[0090] 15° 30° 45° 60° 75° ΔTL(%) -7.14 -6.81 -6.19 -5.06 -2.68 ΔL* -5.94 -5.82 -5.6 -5.04 -3.5 Δa* 1.43 1.4 1.41 1.32 0.96 Δb* 3.21 3.23 2.97 2.32 0.76 ΔE 6.90 6.80 6.49 5.70 3.71

[0091] The decoration slightly reduces the transparency of the glazing, while this reduction in transmission is reduced at grazing incidence.

Claims

1. A motor vehicle corner glazing comprising a first glass sheet intended to be located on the outside of the vehicle, characterized in that The face of the first glass sheet intended to be on the outside of the vehicle, called face 1 , is coated only on a portion thereof with at least one reflective and transparent mineral coating forming a decoration, wherein the light transmittance of the first glass sheet is between 2% and 50%; the or each reflective and transparent mineral coating being such that, when deposited on clear glass, it has a light transmittance of between 40% and 95%; The light reflectivity of the corner glass window is between 15% and 40% when viewed from surface 1 at an incident angle of 45° and in the decorative area; wherein the or each transparent mineral coating forming the decoration has a physical thickness of between 20 and 250 nm; wherein the or each reflective and transparent mineral coating is oxide based; The oxide is selected from titanium oxide, silicon oxide, zirconium oxide, tin oxide, zinc oxide, aluminum oxide, indium oxide and transition metal oxides. 2 . The corner glazing according to claim 1 , further comprising an additional glass sheet, intended to be located on the inside of the vehicle, adhesively bonded to the first glass sheet by means of a thermoplastic laminating interlayer.

3. The corner glazing according to claim 2, wherein the thermoplastic laminating interlayer is a thermoplastic laminating interlayer based on polyvinyl acetal. The corner glass window according to claim 1 , wherein the corner glass window is curved. The corner glass window according to claim 1 , wherein the light transmittance of the first glass sheet is between 8% and 45%.

6. A corner glazing according to claim 1 , wherein the or each reflective and transparent mineral coating is such that when deposited on clear glass it has a light transmission of between 50% and 80%.

7. The corner glazing according to claim 1, such that the first glass sheet is coated with the mineral coating over 5% to 90% of the surface area of ​​the face of the glass sheet.

8. The corner glazing according to claim 1, such that the first glass sheet is coated with the mineral coating over 10% to 80% of the surface area of ​​the face of the glass sheet.

9. An angled glazing according to claim 1, wherein the physical thickness of the or each transparent mineral coating forming the decoration is between 50 and 200 nm.

10. A corner glazing according to claim 1, wherein the or each reflective and transparent mineral coating is a sol-gel coating.

11. Angle glazing according to claim 1, wherein a low-emissivity coating is deposited on the face of the first glass sheet opposite the face bearing the reflective and transparent mineral coating and / or, where appropriate, on one face of the additional glass sheet.

12. Motor vehicle comprising at least one corner glass window according to one of the preceding claims.

13. Method for obtaining a motor vehicle corner glazing according to claim 1, comprising a step of depositing at least one reflective and transparent mineral coating to form a decoration on only a portion of a first glass sheet.

14. A method according to claim 13, wherein the or each reflective and transparent mineral coating is oxide-based, the depositing step comprising screen printing or digital printing a precursor of the oxide. The method according to claim 14 , wherein the precursor of the oxide is a sol.

16. Method according to any one of claims 13 or 14, comprising depositing a reflective and transparent mineral coating on a portion of the face of a first glass sheet, then drying and pre-curing, then conveying on that face, then depositing an opaque layer on the other face, then bending in the case of a single corner glazing, or pre-curing a second time in the case of a laminated corner glazing, assembling with an additional glass sheet, bending the two glass sheets together and finally laminating.

17. The method of claim 16, wherein the opaque layer is enamel.