Method for manufacturing a solar control and / or low-emissivity glazing which is transparent to radiofrequency waves: cracked sol-gel underlayer

Abstract

The present invention relates to a method for manufacturing a glass article, comprising the following steps: - providing a glass substrate; - applying a sol-gel solution to at least one of the faces of said glass substrate, said sol-gel solution comprising at least one silicon oxide precursor and / or at least one transition metal oxide precursor; - drying the sol-gel solution to obtain a dried sol-gel layer having an average thickness of between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm; - heat treatment at a temperature of greater than 350°C, preferably between 400°C and 700°C, so as to crack the dried sol-gel layer; - depositing, above said cracked sol-gel layer, a stack of layers comprising at least one conductive functional layer, each of said layers of the stack being deposited by cathode sputtering assisted by a magnetic field. The present invention also relates to a glass article which can be obtained by such a method and which comprises a glass substrate coated on at least one of its faces with: - at least one sol-gel layer having an average thickness of between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm, said at least one sol-gel layer being formed from at least one silicon oxide precursor and / or at least one transition metal oxide precursor and having cracks or fissures; and - a stack of layers, located above said sol-gel layer and comprising at least one conductive functional layer.

Description

[0001] DESCRIPTION

[0002] Title: Manufacturing process for solar control and / or low-emissivity glazing, transparent to radio frequencies: cracked sol-gel undercoat

[0003] The invention relates to a method for manufacturing a glass article transparent to radio frequencies, the glass article being in particular a solar and / or low-emissivity glazing whose glass substrate is provided with a stack of thin films comprising at least one conductive functional layer. The invention thus relates to the glass article obtained by said method and more particularly to windshields, side windows, or roof windows of motor vehicles, or building glazing, or train glazing comprising such glass articles.

[0004] For the purposes of this application, a "functional layer" is defined as the layer(s) of the stack that provide the stack with the majority of its thermal and / or solar protection properties. A "conductive" functional layer is defined as a layer made of a conductive material. Specifically, a "conductive layer" is defined as a layer with a resistivity per square, denoted "Rsq" (resistivity squared), of less than 500 ohms per square (Q / n).

[0005] In order to reduce greenhouse gas emissions, it is common practice to use so-called "solar control" glazing in buildings, vehicles, and trains. Solar control glazing is glazing designed to limit the flow of energy, particularly solar infrared (SIR) radiation, passing through it from the outside to the inside without compromising light transmission in the visible spectrum. To measure the energy insulation properties of glazing, the total transmitted solar energy (TTS) is used. TTS is the ratio of the energy passing through the glazing (i.e., entering the room) to the incident solar energy.More specifically, it corresponds to the sum of the flux transmitted directly through the glazing and the flux absorbed by the glazing (including any stacked layers present on one of its surfaces) and then re-emitted inwards (into the room) by the glazing. Thus, the lower the TTS value, the better the protection against solar radiation.

[0006] Furthermore, in order to limit energy losses, it is common practice to use so-called "low-emissivity" (or "low-e" in English) insulating glazing which works essentially by reflecting a major part of the incident infrared radiation.

[0007] In particular, with the rise of connected vehicles and the Internet of Things, motor vehicles are now equipped with embedded telecommunications systems (Wi-Fi or Bluetooth transmitters, GPS chips, etc.) enabling wireless communication with the outside environment. These systems can also interact with personal telecommunications devices (cell phones, etc.) belonging to the driver and / or passengers.

[0008] Thus, in addition to solar control and / or low-emissivity properties, it is necessary that glazing for motor vehicles, but also glazing for buildings, exhibit transparency properties to radio electromagnetic waves, in particular radio frequencies, which are commonly used in embedded telecommunication devices.

[0009] However, solar control glazing that also offers good optical performance (light transmission, blur, color, etc.) and low-emissivity glazing with good thermal performance, particularly glazing with a stack of thin films including at least one conductive functional layer, is generally unsuitable for such applications. This is because continuous, conductive functional layers block radio electromagnetic waves, especially radio frequency waves. The radio signal emitted or detected by these telecommunications devices is then weakened, and communication quality becomes poor. Telecommunications may sometimes be impossible.

[0010] As an example, according to the article by Rodriguez et al., "Radio Propagation into Modem Buildings: Attenuation Measurements in the Range from 800 MHz to 18 GHz", 2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall), 2014, pp. 1-5, glazing that includes a stack of layers comprising metallic functional layers can cause attenuation of more than 30dB of telecommunication signals.

[0011] To make the solar control and / or low-emissivity glazing mentioned above transparent to radiofrequency waves, it is known to use tinted glass. However, its solar control performance is significantly reduced.

[0012] Another possibility is the use of a 3M film. However, this film can wrinkle during lamination, which makes its use on an industrial scale complicated.

[0013] Another known method involves etching a conductive functional layer, such as a metallic layer containing silver, after magnetron deposition onto a thin-film glass substrate. This selectively removes the silver in bands or lines approximately 50 µm wide. This etching is performed by a spot laser, also known as laser ablation. This technique has the disadvantages of being very expensive and aesthetically unappealing, as the bands or lines that render the glass transparent to radio frequencies are visible to the naked eye on the glass substrate. Furthermore, laser ablation has low productivity on large panes of glass and requires a significant investment relative to the surface area treated.

[0014] There is therefore a need to find another method for making transparent to radio electromagnetic waves a glass substrate coated with a stack of thin films comprising at least one conductive functional layer, which is less expensive, more reproducible while retaining good solar control properties, good optical and thermal properties for the glass article obtained; the glass article obtained according to the invention also being more aesthetic than the glass article obtained according to the prior art.

[0015] In this application, the term "transparent to radio electromagnetic waves or transparent to radio frequency waves, denoted "RF", means a glass article having a transparency to RF waves similar to that of bare glass, in other words, preferably exhibiting a transmission loss in decibels (dB) between 0 and -5 dB for a frequency ranging from 4 to 14 GHz.

[0016] Furthermore, a glass article transparent to RF waves according to the invention preferably has a profile such that the resistance-per-square parameter, named "Rsq" ("resistivity square" in English), is between 500 Ohm per square (Q / n) to infinity, and in particular greater than 1500 Q / n.

[0017] To this end, the invention relates to a method for manufacturing a glass article comprising the following steps: - the supply of a glass substrate,

[0018] - the application of a sol-gel solution to at least one face of said glass substrate, said sol-gel solution comprising at least one silicon oxide precursor and / or at least one transition metal precursor

[0019] - drying the sol-gel solution to obtain a dried sol-gel layer with an average thickness between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm,

[0020] - heat treatment at a temperature above 350°C, preferably between 400°C and 700°C, so as to crack the dried sol-gel layer,

[0021] - the deposition, above said cracked sol-gel layer, of a stack of layers comprising at least one conductive functional layer, each of said layers of the stack being deposited by magnetic field assisted sputtering.

[0022] Indeed, it was surprisingly observed by the inventors that the presence of at least one sol-gel layer, previously cracked by a heat treatment, and placed between a glass substrate and a stack of layers including at least one conductive functional layer made it possible to damage the functional conductive layer(s) thus making the resulting glass article transparent to radio electromagnetic waves; while having little effect on the solar control, optical and thermal properties of the glass article.

[0023] The inventors thus discovered that at least one cracked sol-gel layer made the conductive functional layers deposited by magnetron above it non-conductive in certain places, thus allowing the production of glass articles transparent to radio electromagnetic waves.

[0024] For the purposes of this application, "cracked sol-gel layer" means a sol-gel layer exhibiting cracks or fissures, advantageously of small width between 0.5 pm and 5 pm.

[0025] A glass article obtained according to the invention can thus be used as laminated or laminated glazing, multiple, double or triple, without problems of wrinkling or lack of adhesion between the layers during lamination or lamination.

[0026] The glass substrate according to the invention is in particular made of soda-lime silicate glass, but it may also be of the borosilicate or aluminosilicate type. Clear soda-lime silicate glasses are preferred. The thickness of the glass substrate can vary between 0.1 mm and 20 mm, in particular between 2 and 8 mm. The glass substrate is preferably in the form of a glass sheet.

[0027] In one embodiment, the glass substrate may be partially or fully coated with an enamel layer. The term "coated" means that the enamel layer is deposited on top of the substrate, but not necessarily in contact with it. Preferably, the enamel layer is in direct contact with the glass substrate. Even more preferably, the enamel layer is in direct contact with the glass substrate and / or the sol-gel layer. The enamel layer, or the enamel itself, consists of a mixture of glass frit (i.e., the glassy phase), inorganic pigments, and organic components, which are a mixture of diluent (organic solvent) and an organic medium (most often based on resin dissolved in a solvent). This ensures good suspension of all the inorganic particles, allowing for their application in the liquid state. The enamel layer may be deposited by screen printing or using the curtain technique.Once applied, the enamel layer can optionally be dried at a temperature below 150°C before being fired at a higher temperature.

[0028] In another embodiment, the substrate may be partially or totally coated with at least one underlayer, preferably totally. The term "coated" means that the underlayer(s) coating the substrate is / are deposited above said substrate, but not necessarily in contact with it. In other words, the underlayer(s) is / are arranged between the glass substrate and the sol-gel layer. Preferably, the underlayer is in direct contact with the glass substrate. Even more preferably, the underlayer is in direct contact with the glass substrate and / or the sol-gel layer. The at least one underlayer may be a dielectric underlayer or a metallic underlayer. It may consist of one or more dielectric underlayers, one or more metallic underlayers, or a mixture of these two types of underlayers.

[0029] In the case of at least one dielectric sublayer, this may include silicon nitride, silicon dioxide, or silicon oxynitride.

[0030] In the case of at least one metallic sub-layer, this may comprise chromium, nickel, niobium, or a mixture of at least two of these elements, said metallic sub-layer possibly being nitrided. These sub-layers may be deposited by magnetic field-assisted vacuum sputtering techniques using a cathode of the material or a precursor of the material to be deposited, often referred to in the field as magnetron sputtering.

[0031] Adding at least one undercoat as described above improves the aesthetics of cracks or fissures in the sol-gel layer obtained after the heat treatment stage of the glass article.

[0032] A sol-gel solution, according to the invention, is applied to at least one of the faces of said glass substrate. The sol-gel solution preferably contains a dry extract of at most 50% by weight, in particular of at most 10% by weight, and generally between 8% and 15% by weight, and even more generally of at least 1% by weight.

[0033] The solvent for the solution is preferably chosen from water, organic solvents, and mixtures of water and organic solvents. Organic solvents are preferably chosen from alcohols (e.g., isopropanol, propanol, ethanol, etc.) and acetone. The term "solvent" is used here in its generic sense, so the solvent may consist of a mixture of solvents.

[0034] In a first embodiment, the sol-gel solution can be aqueous, meaning that the solvent contains at least 50% water by weight, or even 60%, 70%, 80%, or 90% water by weight. Preferably, the solvent is entirely aqueous, meaning it consists of water. The use of aqueous solutions, or at least predominantly aqueous solutions, offers advantages in terms of the environment, industrial hygiene, cost, and also the durability of the resulting layer.

[0035] In a second embodiment, the sol-gel solution can be alcoholic, it contains at least 50% by weight of an alcohol, or even 60%, and even 70% or 80% or even 90% or 95% by weight of an alcohol; the alcohol being chosen for example from isopropanol, propanol and ethanol.

[0036] According to the invention, the sol-gel solution comprises at least one silicon dioxide precursor and / or at least one transition metal oxide precursor. The transition metal is preferably selected from Ti, Al, Zr, Ce, and Zn. The silicon dioxide precursor is preferably an inorganic silicon salt or a silicon alkoxide, and in particular an alkoxysilane. Similarly, the transition metal precursor is preferably an inorganic transition metal salt or a transition metal alkoxide; the transition metal being advantageously selected from Ti, Al, Zr, Ce, and Zn. Thus, the silicon dioxide precursor can be:

[0037] • an inorganic silicon salt of general formula (I) as follows: SiX y , in which X is a halogen, preferably a chlorine, and y is an integer equal to 4, such as silicon tetrachloride with the formula SiCk, or

[0038] • a silicon alkoxide chosen from:

[0039] - alkoxysilanes of general formula (II) as follows: Si(OR 1 )z, in which R 1 is independently chosen from among the C1-C4 alkyls, and z is an integer equal to 4,

[0040] - alkoxysilanes of general formula (III) as follows: Si(OR 1 )4-kR 2 k, in which R 1 is independently chosen from among the C1-C4 alkyls, k is an integer between 1 and 3, and R 2 is independently an alkyl group substituted by a reactive or non-reactive function, and

[0041] - a mixture of these alkoxysilanes.

[0042] The term "reactive function" refers to a function chosen from the group consisting of epoxy, carboxylic acid, amine, acrylate, methacrylate, vinyl, isocyanate, thiol, thiocyanate, and hydroxyl.

[0043] The preferred alkoxysilanes according to general formula (II) are: tetraethyl orthosilicate and tetramethyl orthosilicate, and the preferred alkoxysilanes according to general formula (III) are: tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, and methacryloxypropyltrimethoxysilane.

[0044] Thus, the preferred precursor of transition metal oxide is:

[0045] - an inorganic salt of general formula (IV) as follows: MX y, in which M is chosen from Ti, Al, Zr, Ce and Zn, X is a group chosen from chlorides, nitrates, acetates, and y is an integer between 2 and 4, such as titanium tetrachloride, aluminum chloride, cerium chloride, aluminum nitrate, cerium nitrate or zinc acetate or

[0046] - a transition metal alkoxide of general formula (V) as follows: M(OR)z, in which M is chosen from Ti, Al, Zr, Ce and Zn, R is independently chosen from the C1-C4 alkyls, z is an integer between 2 and 4. The preferred transition metal alkoxides according to general formula (V) are: tetrabutyl orthotitanate, tetraethyl orthotitanate, tetramethyl orthotitanate, tetrapropyl orthotitanate, titanium isopropoxide, aluminum isopropoxide, aluminum tri-sec butoxide, zirconium isopropoxide, and zirconium propoxide.

[0047] The sol-gel solution may include other components, such as complexing agents, porogens, pH regulating agents, surfactants, nanoparticles, nanopigments, ...

[0048] A pore-forming agent, according to the invention, may be solid, its size being chosen to allow for variation in pore size. The pore-forming agent may be particulate, particularly of a substantially spherical shape, for example in the form of hollow or solid beads. The pore-forming agent is preferably organic in nature. By way of example, the pore-forming agent comprises polymeric beads, in particular of a polymer selected from polymethyl methacrylate (PMMA), methyl (meth)acrylate / (meth)acrylic acid copolymers, polycarbonates, polyesters, and polystyrene.

[0049] The sol-gel solution to be applied is preferably acidic. Its pH is preferably between 0 and 5, particularly between 1 and 3.

[0050] The application of the sol-gel solution is preferably carried out by coating using at least one roller, a technique also known as "roll coating," which allows for precise control of the amount of solution deposited as well as the spatial homogeneity of the deposit. According to this technique, the glass substrate is preferably passed under a metering roller and an applicator roller that are almost touching each other and rotating in the same or opposite directions. The applicator roller is in contact with the surface of the substrate to be coated, and the solution is poured from above between these two rollers. The solution, passing between the metering roller and the applicator roller, is deposited on the surface of the latter and then transferred to the surface to be coated.

[0051] The gel solution can also be deposited by curtain coating, slit coating, dip coating, blade coating, spraying, or inkjet printing.

[0052] Immediately after the application of the sol-gel solution, and before the heat treatment step, the process according to the invention includes a drying step. This step is designed to accelerate the evaporation of the solvent contained in the sol-gel solution and to consolidate the solution to form a dried sol-gel layer with an average thickness of between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm. The purpose of this drying step is to obtain a sol-gel layer that is solid to the touch, in other words, one that is no longer liquid, in order to prevent the accumulation of dust. It can be carried out by any known means, for example, by blowing hot air, by infrared radiation, or by vacuum drying.

[0053] For the purposes of this invention, "average thickness of the sol-gel layer" means the average geometric thickness of the layer, as measured in particular by classical scanning electron microscopy or other techniques, such as ellipsometry.

[0054] After the sol-gel layer has dried, a first heat treatment step cracks the dried sol-gel layer. This heat treatment is carried out at a temperature above 350°C, preferably between 400°C and 700°C. Annealing is the preferred method and can be performed using a furnace.

[0055] The heat treatment in the process as defined in this application primarily creates random cracks or fissures on the dried sol-gel layer, without forming any particular patterns, thus creating a cracked sol-gel layer. This damages the conductive layer(s) deposited above, rendering the resulting glass article transparent to radio waves. It should be noted that the cracks or fissures present on the dried sol-gel layer are advantageously barely visible to the naked eye, as their width can range from 0.5 µm to 5 µm.

[0056] The heat treatment step, according to the process of the invention, is followed by the deposition of a stack of layers comprising at least one conductive functional layer, above said cracked sol-gel layer, each of said layers of the stack being deposited by magnetic field-assisted sputtering. In a preferred embodiment, the stack of layers comprising at least one conductive functional layer is in direct contact with the cracked sol-gel layer.

[0057] The layer stack according to the invention comprises at least one conductive functional layer. A conductive functional layer is a layer capable of acting on solar radiation and / or long-wavelength infrared radiation, as previously stated. The conductive functional layer(s) comprise at least one conductive material selected from silver, tin, titanium nitride, indium and its oxides, and silicon. These conductive functional layers are, for example and preferably, metallic functional layers based on silver or a metallic alloy containing silver, or ITO-based layers. The ITO-based layers can form a layer stack comprising, successively from the cracked sol-gel layer, a silicon nitride layer, a silicon dioxide layer, an ITO layer, a silicon nitride layer, and / or a silicon dioxide layer.

[0058] The layer stacking may successively include, starting from the cracked sol-gel layer, an alternation of x conductive functional layers and (x+1) anti-reflective coatings, each anti-reflective coating comprising at least one dielectric layer, so that each conductive functional layer is arranged between two anti-reflective coatings.

[0059] According to an alternative, the thin-film stacking may successively comprise, starting from the cracked sol-gel layer, an alternation of two conductive functional layers, in particular two conductive functional layers based on silver or a silver-containing metallic alloy, and three anti-reflective coatings, each anti-reflective coating comprising at least one dielectric layer, so that each conductive functional layer is disposed between two anti-reflective coatings.

[0060] According to another alternative, the thin-film stacking may successively comprise, starting from the cracked sol-gel layer, an alternation of three conductive functional layers, in particular three conductive functional layers based on silver or silver-containing metallic alloy, and four anti-reflective coatings, each anti-reflective coating comprising at least one dielectric layer, so that each metallic functional layer is disposed between two anti-reflective coatings.

[0061] The thickness of the thin film stack can be greater than 70 nm, and less than 400 nm.

[0062] The layer stack deposition step, which includes at least one conductive functional layer, may be followed by a second heat treatment at a temperature above 500°C, preferably between 540°C and 700°C. This second heat treatment is preferably a tempering, bending, or annealing treatment of the glass, and more preferably a tempering treatment. Tempering glass involves heating the glass to a temperature generally above 500°C and then rapidly cooling it, usually using nozzles emitting cold air. This rapid cooling creates compressive stresses on the surface of the glass substrate, thus increasing its mechanical strength and impact resistance.

[0063] According to another preferred embodiment, the manufacturing process for the glass article may further comprise, after the deposition of the layer stack or after the second heat treatment, the following successive steps:

[0064] - the deposition of a sheet, or interlayer film, of a material selected from poly(vinyl butyral) (PVB), poly(ethylene-vinyl acetate) (EVA) and polyurethane (PU) and mixtures thereof,

[0065] - the supply of a second glass substrate, and

[0066] - assembly of the whole (i.e. the first glass substrate bearing the cracked sol-gel layer and the damaged layer stack / the interlayer film and the second glass substrate) by lamination to form a laminated glazing.

[0067] Therefore, the process according to the invention makes it possible to obtain glass articles transparent to radio electromagnetic waves, thanks to the presence of at least one cracked sol-gel layer disposed beneath a stack of layers comprising at least one conductive functional layer. Indeed, the inventors discovered that said cracked sol-gel layer damaged all the magnetron-deposited conductive functional layers above it, thus rendering them non-conductive in certain areas, as demonstrated by the measurement of a loss of conductivity at these locations, without impacting the solar control, thermal, and optical properties of the glass article in areas where the gel layer was not cracked.

[0068] An object of the invention is therefore also a glass article, in particular capable of being obtained by the process according to the invention, which comprises a glass substrate coated on at least one of its faces:

[0069] - of at least one sol-gel layer having an average thickness between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm, the at least said sol-gel layer being formed from at least one precursor of silicon oxide and / or at least one precursor of titanium or zirconium or aluminium oxide and exhibiting cracks or fissures, and - of a stack of layers located above said sol-gel layer comprising at least one conductive functional layer.

[0070] The layer stacking, including at least one conductive functional layer, is preferably as described above. The cracked sol-gel layer may have a refractive index between 1.3 and 2.5, preferably between 1.4 and 1.8, and more preferably between 1.4 and 1.6, measured at a wavelength of 630 nm.

[0071] In addition, the inventors noted that by varying the nature of the sol-gel layer precursors, the thickness of the sol-gel layer had to be adjusted in order to be able to crack it during the first heat treatment.

[0072] Thus, in a preferred embodiment, the sol-gel layer comprising silicon dioxide has an average thickness of between 300 nm and 3000 nm.

[0073] In another preferred embodiment, the sol-gel layer comprises titanium dioxide or zirconium dioxide and has an average thickness of between 70 nm and 1000 nm.

[0074] In a preferred embodiment, the sol-gel layer is in direct contact with the glass substrate.

[0075] In another preferred embodiment, the glass article may further comprise an enamel layer, as described above, the enamel layer being disposed between the glass substrate and the cracked sol-gel layer. More preferably, the enamel layer is in direct contact with the glass substrate and / or the sol-gel layer.

[0076] As stated previously, the inventors discovered that the presence of at least one sol-gel layer, cracked beforehand by a heat treatment, and arranged between a glass substrate and a stack of layers including at least one conductive functional layer, made it possible to render the glass article transparent to radio electromagnetic waves while having little effect on the solar control, optical, and thermal properties of the glass article.

[0077] Therefore, the Applicant proposes a glass item preferably possessing:

[0078] - a radio frequency wave transparency measurement denoted "RF" ranging from 0 to -5 dB, preferably from 0 to -2 dB for a frequency ranging from 4 to 14 GHz;

[0079] - a resistance "Rsq" ranging from 500 ohms per square (Q / n) to infinity, and in particular greater than 1500 Q / n; - a light transmission "TL" greater than 30% in particular for motor vehicle roof windows and greater than 70% in particular for windscreens, in the range of wavelengths of the visible spectrum;

[0080] - small cracks or fissures of width between 0.5 pm and 5 pm;

[0081] - a total solar energy transmitted (TTS) value of less than 60%, preferably less than 55%; and

[0082] - a normal emissivity "s n "particularly for non-laminated (or non-coated) glazing with an emissivity below 2.5; emissivity being defined by the relation: s n= 1 - Rn, in which R n is the reflection factor according to the normal (according to Annex A of the international standard ISO 10292 (1994) and according to the standard NF EN 12898 (2019)) of the glazing.

[0083] In general, all the luminous characteristics presented in this description, in particular the light transmission "TL" and the total solar energy transmitted "TTS", are obtained according to the principles and methods described in the standard NF EN 410 (2011) relating to the determination of the luminous and energy characteristics in the visible range of glazing used in automotive glass.

[0084] The glass articles obtained according to the invention can thus be advantageously used as single or monolithic glazing (a single glass substrate), or as multiple glazing, for example double glazing, or even as laminated or laminated glass, without any problems during the lamination or lamination process. Laminated or laminated glass is conventionally understood to mean glazing comprising at least two glass substrates joined by a plastic film, for example of the polyvinyl butyral (PVB), poly(ethylene-vinyl acetate) (EVA), polyurethane (PU), or a mixture thereof type. In this case, the sol-gel layer and the layer stacking, as defined above, are preferably deposited on one of the inner faces of the laminated glass, that is to say, on face 2 or 3 of the glass, the faces being conventionally numbered from 1 to 4 from the outside to the inside of the glass.

[0085] The invention also relates to a windscreen, a side window, or a roof window of a motor vehicle, or a building window, or a train window comprising a glass article as defined above.

[0086] EXAMPLES The following examples illustrate the invention in a non-limiting manner.

[0087] In all examples below, the substrates used are 4 mm thick soda-lime-silicon sheets of the Planiclear® type marketed by the company Saint-Gobain Glass France.

[0088] All the layers of the stacks were deposited using conventional vacuum magnetron sputtering deposition techniques.

[0089] Examples according to the invention

[0090] In all the examples according to the invention that follow, the sol-gel layer is prepared and then applied to a glass substrate as follows:

[0091] After hydrolysis at 60°C under reflux for 1 h, a sol-gel liquid solution was obtained from a mixture of 80.2 g of tetraethyl orthosilicate (TEOS) of formula Si(0Et)4, 142.1 g of ethanol and 27.7 g of 0.05 mol hydrochloric acid. 1 , is applied to a glass substrate by dipping coating.

[0092] The sol-gel solution is dried for 10 minutes on a hot plate at 100°C and the average thickness of the sol-gel layer thus formed is 600 nm.

[0093] The glass substrate and the dried sol-gel layer then undergo an initial heat treatment as they are heated to 650°C for 10 minutes using an oven in order to obtain a cracked sol-gel layer.

[0094] Then, each of the layer stacks described below is then deposited on a cracked sol-gel layer as obtained above, to form a glaze.

[0095] •Single-silver stacking:

[0096] This stack of thin layers comprises successively, from the cracked sol-gel layer, a silver layer and two anti-reflective coatings; each anti-reflective coating comprising at least one dielectric layer, so that each silver layer is arranged between two anti-reflective coatings.

[0097] Thus, stack 1 comprises, starting from the cracked sol-gel layer, the following thin layers:

[0098] Si3N4(20nm) / SnZNO (10nm) / ZnO (5nm) / Ag (10nm) / ZnO (5nm) / SnZnO (10nm) / S i3N4(20nm) / TiOx (1nm). •Stack 2 of tri-silver type:

[0099] This stack of thin layers comprises successively, starting from the cracked sol-gel layer, an alternation of three layers of silver and four anti-reflective coatings, each anti-reflective coating comprising at least one dielectric layer, so that each layer of silver is arranged between two anti-reflective coatings.

[0100] Thus, stacking 2 comprises, starting from the cracked sol-gel layer, the following thin layers:

[0101] SiO2(10 nm) / SnZnO (9.2 nm) / AZO (5 nm) / Agi (7.4 nm) / Ti (0.9 nm) / AZO (4.3 nm) / Si3N4(58.1 nm) / SnZnO (7.7 nm) / AZO (5 nm) / Ag2(12.9 nm) / Ti (0.7 nm) / AZO (5.9 nm) / S i3N4 (51.6 nm) / SnZnO (9.6 nm) / AZO (8.1 nm) / Ag3 (16 nm) / Ti (1.2 nm) / AZO (5.7 nm) / Si3N4 (23.8 nm) / SnZnO (5.4 nm).

[0102] • Stack 3: ITO-based stacking:

[0103] This stacking consists of the following thin layers starting from the cracked sol-gel layer:

[0104] Si3N4(60 nm) / SiO2(30 nm) / ITO (60 nm) / Si3N4(20 nm) / SiO2(30 nm).

[0105] Each of the three resulting glass panes then undergoes a second heat treatment, which is annealing by heating in a furnace at 650°C. A PVB sheet is then deposited on the top layer of each of the three glass layers, followed by the deposition of a second glass substrate. Each pane is then laminated to form the following three laminated glass panes:

[0106] Laminated glazing 1: glass substrate / cracked sol-gel layer / damaged stack 1 / PVB / glass substrate

[0107] Laminated glazing 2: glass substrate / cracked sol-gel layer / damaged stack 2 / PVB / glass substrate

[0108] Laminated glazing 3: glass substrate / cracked sol-gel layer / damaged stack 3 / PVB / glass substrate.

[0109] The comparative examples are laminated glazings identical to glazings 1, 2, 3 described above except that they do not include any sol-gel layer as follows: Laminated glazing 1bis: glass substrate / stack 1 / PVB / glass substrate Laminated glazing 2bis: glass substrate / stack 2 / PVB / glass substrate Laminated glazing 3bis: glass substrate / stack 3 / PVB / glass substrate.

[0110] A-Measurement of glazing characteristics

[0111] The radio frequency transparency, optical and solar control characteristics of the glazing obtained according to the examples were measured according to the following principles and standards:

[0112] 1°) Transparency properties to radio frequency waves

[0113] RF transparency measurements are performed in an anechoic chamber, a chamber isolated from all external waves. Measurements are taken by sending a 4 to 14 GHz wave through the glass, and an antenna placed on the other side captures the received signal. The RF value considered is that between 6 and 14 GHz.

[0114] Transparency properties to radio frequency waves are also evaluated by determining the resistance "Rsq", using a measuring device called Nagy.

[0115] 2°) Optical properties and solar control

[0116] The measurements are carried out in accordance with the European standard NF EN 410 (2011). More specifically, the light transmission "TL" is measured between 380 and 780 nm depending on the illuminant Des.

[0117] The solar control properties of the glazing are evaluated by determining the total solar energy transmitted "TTS" according to the conditions described in standard NF EN 410 (2011).

[0118] 3°) Aesthetic properties

[0119] The width of the cracks is measured using an optical microscope.

[0120] B-Results

[0121] The results obtained for laminated glazing according to the examples described above are grouped in Table 1 below: [Table 1]

[0122] The results reported in this table show that laminated glazing units 1, 2, and 3 obtained according to the invention (i.e., comprising a cracked sol-gel layer with fine cracks or fissures approximately 0.7 µm wide) transmit radio electromagnetic waves compared to laminated glazing units 1bis, 2bis, and 3bis, which do not include said cracked sol-gel layer. This is because laminated glazing units 1, 2, and 3 according to the invention exhibit a radio frequency transparency value close to 0 dB (RF between 0 and -2 dB) and a very high resistance per square (on the order of infinity or greater than 5000 Q / n), whereas the RF value of laminated glazing units 1bis, 2bis, and 3bis (without said cracked sol-gel layer) is far from 0 dB (RF less than -18 dB), and the resistance per square is much lower and equal respectively to 7.7 Q / n / 1.7 Q / n / 26 Q / n.

[0123] On the other hand, it is observed that the presence of the cracked sol-gel layer does not modify the optical properties of the laminated glazing which has it, since the light transmission does not vary almost between a laminated glazing obtained according to the invention and a laminated glazing outside the invention (glazing 1 / glazing 1bis with a respective TL equal to 73.8 / 74.7 and glazing 2 / glazing 2bis with a respective TL equal to 54.6 / 57.9 and glazing 3 / glazing 3bis with a respective TL equal to 51 t 52.8).

[0124] Furthermore, the presence of the cracked sol-gel layer does not alter the solar control properties of the laminated glazing which has it, since the total solar energy transmitted varies very little between a laminated glazing obtained according to the invention and a laminated glazing outside the invention (glazing 1 / glazing 1bis with a respective TTS equal to 58.4 / 59.1 and glazing 2 / glazing 2bis with a respective TTS equal to 28.2 / 29.7 and glazing 3 / glazing 3bis with a respective TTS equal to 44.9 / 46.1).

[0125] Other Examples

[0126] Two other glazing options, glazing 4 according to the invention and glazing 4bis outside the invention (or comparative), are obtained by depositing a layer of enamel by screen printing:

[0127] - either between the glass substrate and the cracked sol-gel layer (obtained according to the example above); the said cracked sol-gel layer being coated with a damaged stack 2 to form the following glazing 4: glass substrate / enamel layer / cracked sol-gel layer / damaged stack 2;

[0128] - either between the first glass substrate and a stack 2 to form the following glazing 4bis: glass substrate / enamel layer / damaged stack 2.

[0129] It should be noted that since these panes of glass are opaque (because they are coated with a layer of enamel), the TL and TTS values ​​do not need to be measured, and cracks or fissures, being invisible, do not need to be measured. The results obtained for the panes of glass according to the examples described above are summarized in Table 2 below:

[0130] [Table 2]

[0131] It is similarly observed that the glazing 4 obtained according to the invention (i.e. comprising a cracked sol-gel layer) allows radio electromagnetic waves to pass through compared to the glazing 4 (outside the invention) without said cracked sol-gel layer, since the glazing 4 according to the invention has a radio frequency transparency value close to 0 dB (RF between 0 and -2 dB) compared to the glazing 4 bis whose RF has a value between -15 and 25 dB.

Claims

Demands 1. A method for manufacturing a glass article comprising the following steps: - the supply of a glass substrate, - the application of a sol-gel solution to at least one face of said glass substrate, said sol-gel solution comprising at least one silicon oxide precursor and / or at least one transition metal oxide precursor, - drying the sol-gel solution to obtain a dried sol-gel layer with an average thickness between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm, - heat treatment at a temperature above 350°C, preferably between 400°C and 700°C, so as to crack the dried sol-gel layer, - the deposition, above said cracked sol-gel layer, of a stack of layers comprising at least one conductive functional layer, each of said layers of the stack being deposited by magnetic field assisted sputtering.

2. A method according to claim 1, wherein the application of the sol-gel solution to the glass substrate is carried out by roller coating, curtain coating, slit coating, dip coating, blade coating, spraying, squirting, or inkjet printing.

3. A process according to claim 1 or 2, wherein the silicon oxide precursor is: • an inorganic silicon salt of general formula (I) as follows: SiX y , in which X is a halogen and y is an integer equal to 4, or • a silicon alkoxide chosen from: the alkoxysilanes of general formula (II) as follows: Si(OR 1 )z in which R1 is independently chosen from among the C1-C4 alkyls, and z is an integer equal to 4, the alkoxysilanes of general formula (III) as follows: Si(OR 1 )4-kR 2 k in which R 1 is independently chosen from among the C1-C4 alkyls, k is an integer between 1 and 3, and R 2 is independently an alkyl group substituted by a reactive or non-reactive function, and a mixture of these alkoxysilanes.

4. A process according to claim 1 or 2, wherein the transition metal oxide precursor is: - an inorganic salt of general formula (IV) as follows: MX y , in which M is chosen from Ti, Al, Zr, Ce and Zn, X is a group chosen from chlorides, nitrates, acetates, and y is an integer between 2 and 4, or - a transition metal alkoxide of general formula (V) as follows: M(OR)z, in which M is chosen from Ti, Al, Zr, Ce and Zn, R is independently chosen from the C1-C4 alkyls, z is an integer between 2 and 4.

5. A method according to any one of the preceding claims, wherein the glass substrate is coated in whole or in part with a layer of enamel before the application of the sol-gel solution.

6. A method according to any one of the preceding claims, wherein the layer stacking successively comprises, from the cracked sol-gel layer, an alternation of x conductive functional layers and (x+1) anti-reflective coatings, each anti-reflective coating comprising at least one dielectric layer, such that each conductive functional layer is arranged between two anti-reflective coatings.

7. A method according to any one of the preceding claims, wherein the conductive functional layer(s) comprises at least one conductive material selected from silver, tin, titanium nitride, indium and its oxides, and silicon.

8. A method according to any one of the preceding claims, comprising in or in addition, after the layer stack deposition step, a second heat treatment at a temperature above 500°C, preferably between 540°C and 700°C.

9. A process according to claim 8, wherein the second heat treatment is: quenching, bending or annealing.

10. Glass article, which can be obtained according to the process of any one of claims 1 to 9, comprising a glass substrate coated on at least one of its faces: - of at least one sol-gel layer having an average thickness between 50 nm and 3000 nm, preferably between 70 nm and 1500 nm, the said sol-gel layer being formed from at least one silicon oxide precursor and / or at least one transition metal oxide precursor and exhibiting cracks or fissures, and - of a stack of layers located above said sol-gel layer comprising at least one conductive functional layer.

11. Glass article according to claim 10, characterized in that the cracked sol-gel layer has a refractive index between 1.3 and 2.5, preferably between 1.4 and 1.8, and more preferably between 1.4 and 1.6, measured at a length of 630 nm.

12. Glass article according to claim 10 or 11, wherein the width of the cracks or fissures in the sol-gel layer is between 0.5 pm and 5 pm.

13. Glass article according to any one of claims 10 to 12, further comprising an enamel layer disposed between the glass substrate and the cracked sol-gel layer.

14. Windscreen, side window, or roof window of a motor vehicle, or building glazing, or train glazing comprising a glass article, according to any one of claims 10 to 13.

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