Window pane with a scratch-resistant emissivity-reducing coating

Abstract

The present invention relates to a window pane with an emissivity-reducing coating, comprising at least a glass pane (2) and an emissivity-reducing coating (10) on a surface of the glass pane (2), wherein the emissivity-reducing coating (10), starting from the surface of the glass pane (2), comprises, in the following order, an electrically conductive layer (13) based on a transparent conductive oxide, a dielectric upper antireflection layer (15) with a refractive index of at most 1.6, and a DLC layer (16), wherein the dielectric upper antireflection layer (15) is arranged immediately adjacently to the DLC layer (16).

Description

[0001] SAINT-GOBAIN SEKURIT FRANCE 1

[0002] Window pane with a scratch-resistant, emissivity-reducing coating

[0003] The invention relates to a window pane with a scratch-resistant, emissivity-reducing coating, a method for its manufacture and its use.

[0004] It is known that window panes can be equipped with emissivity-reducing coatings to improve thermal comfort in the interior space enclosed by the window pane. Such coatings are also known as heat-reflective coatings, low-emissivity coatings, or low-E coatings and are commonly used, for example, on vehicle roof windows. The emissivity-reducing coating is applied specifically to the interior surface of the window pane, the side facing the interior. It exhibits reflective properties, particularly in the mid-infrared spectral range, and therefore reflects heat radiation. At low outside temperatures, the coating reduces the radiation of heat from the interior and thus prevents the interior from cooling down.At high ambient temperatures, the coating partially blocks the infrared radiation components of sunlight, thereby reducing the heat radiation from the heated window pane into the interior. The IR-reflective properties are typically provided by a corrosion-resistant, electrically conductive layer, for example, based on a transparent conductive oxide (TCO) such as indium tin oxide (ITO). Dielectric layers are also usually present, serving to improve optical properties and / or protect the conductive layer.

[0005] Emissivity-reducing coatings of this type have been described in many publications. By way of example, reference is made to WO 2018 / 206236 A1, WO 2023 / 237839 A1, US2015017355A1 and US2015291471A1.

[0006] Window panes are frequently subjected to heat treatment, for example, to thermally prestress or bend them. Since the coating is typically applied to the flat pane before the heat treatment or bending process, this places high demands on the coating. The coating must withstand the heat treatment without developing cracks or other damage. WO 2013 / 131667 A1 discloses a bendable emissivity-reducing coating, wherein the bendability is ensured by a dielectric barrier layer for regulating oxygen diffusion above the TCO layer with a thickness of 10 nm to 40 nm.

[0007] WO 2021 / 105959 A1 discloses an emissivity-reducing coating with a very thin metallic layer in direct contact with the TCO layer with a thickness of 3 nm to 10 nm.

[0008] Emissivity-reducing coatings are generally not intended for regular or repeated mechanical stress. This means that in applications where the coating is subjected to regular mechanical stress, such as by the sealing lip of a movable side window in a vehicle during the up and down movement of the window, there is a high risk of the coating being damaged in the long term.

[0009] For many applications, it is therefore desirable to provide an emissivity-reducing coating with improved scratch resistance, as even minor scratches are clearly visible and detract from the aesthetic appearance of the coated transparent substrate. Furthermore, the integrity of the surface is no longer fully guaranteed. This not only impairs the visual appearance of the coated transparent substrate but can also impair transparency if scratches occur repeatedly.

[0010] Layers or coatings made of diamond-like carbon (DLC) are suitable for improving the scratch resistance of substrates. WO 92 / 05951 A1 describes DLC-coated transparent substrates, wherein the DLC layer, at least 20 nm thick, is applied to an intermediate layer previously deposited on the substrate surface, and both layers are formed using a chemical vapor deposition (CVD) process.

[0011] WO 2019 / 020485 A1 discloses a coated substrate, wherein the coating, starting from the substrate, comprises in the specified order a layer of diamond-like carbon, a metallic single- or multi-layer layer, and an oxygen barrier layer, wherein the metallic single- or multi-layer layer contains tin or tin and at least one alloying element for tin, which is present in an unalloyed and / or alloyed form, or magnesium and at least one alloying element for magnesium, which is present in an unalloyed and / or alloyed form. The substrate coated in this way protects the DLC layer, thereby making it temperature-resistant.

[0012] WO 2023 / 275493 A1 discloses a substrate coated with a stack of layers comprising, starting from the surface of the substrate, the following layer sequence: - a layer of diamond-like carbon; - a germanium or germanium oxide layer with a thickness between 2 and 40 nm, wherein the germanium or germanium oxide layer contains less than 20% tin; and - optionally an oxygen barrier layer.

[0013] FR 3012821 A1 discloses a process for producing a photocatalytic material comprising a substrate and at least one thin titanium oxide-based layer applied to a first side of the substrate, the process comprising the following steps: - applying the at least one thin titanium oxide-based layer, - applying a temporary carbon-based inorganic protective layer to the thin titanium oxide-based layer, - subjecting the material to heat treatment at a temperature above 350 °C.

[0014] US 2012 / 164420 A1 discloses an emissivity-reducing coating comprising the layer sequence glass sheet / SiNx / TiOx / SiOxNy / ITO / SiNx / ZrOx starting from the surface of the glass sheet. Optionally, a DLC layer can be applied directly over and in contact with the zirconia.

[0015] There is a need for window panes with emissivity-reducing coatings that are scratch-resistant and easy to manufacture. The present invention aims to provide such an improved window pane.

[0016] The object of the present invention is achieved according to the invention by a window pane and a method for manufacturing a window pane according to the dependent claims. Preferred embodiments are described in the sub-claims.

[0017] The window pane according to the invention with emissivity-reducing coating comprises at least:

[0018] - a pane of glass and

[0019] - an emissivity-reducing coating on one surface of the glass pane. Starting from the surface of the glass pane, the emissivity-reducing coating comprises, in the following order:

[0020] - an electrically conductive layer based on a transparent conductive oxide (TCO)

[0021] - a dielectric upper anti-reflective coating with a refractive index of at most 1.6 and

[0022] - a layer of diamond-like carbon (DLC).

[0023] According to the invention, the dielectric upper anti-reflective layer is arranged directly adjacent to the layer of diamond-like carbon. Thus, no further layer is arranged between the dielectric upper anti-reflective layer and the layer of diamond-like carbon.

[0024] Layers of diamond-like carbon are well known. Diamond-like carbon is commonly abbreviated as DLC (for "diamond-like carbon"). The layer of diamond-like carbon will also be referred to as a DLC layer in the following. In DLC layers, hydrogen-free or hydrogen-containing amorphous carbon is the predominant component, with the carbon consisting of a mixture of sp 3 - and sp 2 -hybridized carbon may be present, if necessary sp 3 -hybridized carbon or sp 2 Hybridized carbon predominates. Examples of DLCs are those designated t:aC and a:CH. A DLC layer can also contain foreign atoms, such as silicon, metals, oxygen, nitrogen, or fluorine, as dopants. The DLC layer used according to the invention can be doped or undoped.

[0025] If a first layer is arranged above a second layer, this means, according to the invention, that the first layer is arranged further away from the glass pane than the second layer. If a first layer is arranged below a second layer, this means, according to the invention, that the second layer is arranged further away from the glass pane than the first layer.

[0026] If a first layer is positioned above or below a second layer, this does not necessarily mean that the two layers must be in direct contact. Optionally, at least one further layer may be positioned between the first and second layers, unless this is explicitly excluded. If a first layer is positioned directly below or above a second layer, then the first layer is in direct contact with the second layer, and no further layer is positioned between the two layers.

[0027] Typically and preferably, the emissivity-reducing coating comprises, in addition to the dielectric upper anti-reflective layer, further dielectric layers. These dielectric layers are arranged below the DLC layer and are specifically designed to protect the electrically conductive layer and to adjust the optical properties of the coating. In a typical and advantageous embodiment, the emissivity-reducing coating comprises, starting from the surface of the glass pane, the following in the specified order:

[0028] - a lower dielectric layer or sequence of layers,

[0029] - the electrically conductive layer based on a transparent conductive oxide,

[0030] - a dielectric barrier layer to regulate oxygen diffusion,

[0031] - a dielectric upper anti-reflective coating with a refractive index of at most 1.6, and

[0032] - a layer of diamond-like carbon (DLC) ,

[0033] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0034] The emissivity-reducing coating of the window pane according to the invention is a thin-film stack, i.e., a sequence of thin individual layers. It is particularly transparent, so that the light transmission of the window pane is not excessively reduced and visibility through the window pane is possible.

[0035] Emissivity-reducing coatings are also known as heat-radiation-reflecting coatings, low-emissivity coatings, or low-E coatings. Emissivity refers to the measure that indicates how much heat radiation a pane emits into an interior space compared to an ideal heat radiator (a black body). Emissivity-reducing coatings prevent heat from entering the interior (infrared components of solar radiation and, in particular, the thermal radiation from the pane itself) and also prevent heat from radiating out of the interior. They exhibit reflective properties towards infrared radiation, especially heat radiation in the spectral range of 5 pm to 50 pm (see also standard DIN EN 12898:2019-06). This effectively improves thermal comfort in the interior.The emissivity-reducing coatings can, at high outside temperatures and solar radiation, at least partially reflect the heat radiation emitted by the entire pane towards the interior. At low outside temperatures, they can reflect the heat radiation emitted from the interior, thus reducing the effect of the cold pane as a heat sink.

[0036] The interior emissivity of the window pane according to the invention is preferably less than or equal to 40%, particularly preferably less than or equal to 35%, and most preferably less than or equal to 30%. Interior emissivity is defined here as the normal emissivity at 283 K according to the standard DIN EN 12898:2019-06.

[0037] The emissivity-reducing coating is typically applied across the entire surface of the glass pane. A circumferential edge area and / or other localized areas, for example those used for data transmission, may be left uncoated. The coated portion of the substrate surface is preferably at least 80%, and particularly preferably at least 90%. However, a full-surface emissivity-reducing coating is preferred.

[0038] Refractive indices are generally specified within the scope of the present invention with reference to a wavelength of 550 nm. The refractive index is fundamentally independent of the measurement method. It can, for example, be determined by ellipsometry. Ellipsometers are commercially available, for example from Sentech.

[0039] Unless otherwise specified, the stated layer thicknesses or thicknesses refer to the geometric thickness of a layer. If the optical thickness is meant instead, this will be explicitly stated. The optical thickness within the meaning of the invention is the product of the geometric thickness and the refractive index at 550 nm.

[0040] The oxides, nitrides, fluorides, and carbides mentioned in this description may have been deposited stoichiometrically, substoichiometrically, or superstoichiometrically with respect to their oxygen, nitrogen, fluorine, or carbon content, respectively. This also applies if, for the sake of simplicity and better understanding, stoichiometric formulas are given in the description of the materials.

[0041] If a layer (thin film) of a coating is formed based on a material, the layer consists predominantly of that material, in particular essentially of that material, along with any impurities or dopants. The materials may contain dopants, in particular aluminum, boron, antimony, zirconium, tungsten, or titanium. The dopants can impart a certain electrical conductivity to materials that are inherently dielectric. However, those skilled in the art will still identify them as dielectric layers with regard to their function, as is customary in the field of thin films. The material of the dielectric layers preferably has an electrical conductivity (inverse of the resistivity) of less than 10⁻⁴. 4 S / m. The material of the electrically conductive layer preferably has an electrical conductivity greater than 10. 4S / m. The proportion of doping is preferably less than 10 wt.%, particularly preferably less than 5 wt.%.

[0042] The thickness of the DLC layer is preferably from 1 nm to 20 nm, particularly preferably from 2 nm to 10 nm, and most preferably from 3 nm to 7 nm.

[0043] The electrically conductive layer based on a transparent conductive oxide (TCO layer) provides the IR-reflective properties of the emissivity-reducing coating. TCO layers are corrosion-resistant and can be used on exposed surfaces. The refractive index of the TCO layer is preferably between 1.7 and 2.3.

[0044] The electrically conductive layer is preferably based on indium tin oxide (ITO), which has proven particularly advantageous, especially due to its low specific resistance and low scatter in sheet resistance. Alternatively, the conductive layer can also be based, for example, on indium zinc mixed oxide (IZO), gallium-doped tin oxide (GZO), fluorine-doped tin oxide (FTO, SnO₂:F), antimony-doped tin oxide (ATO, SnO₂:Sb), or niobium-doped titanium oxide (TiO₂:Nb).

[0045] The thickness of the TCO layer is preferably from 30 nm to 150 nm, particularly preferably from 50 nm to 130 nm, for example from 60 nm to 100 nm. This achieves particularly good results with regard to electrical conductivity while maintaining sufficient optical transparency.

[0046] The refractive index of the dielectric upper anti-reflective coating is, as described above, at most 1.6 (i.e., less than or equal to 1.6), preferably from 1.3 to 1.6. The dielectric upper anti-reflective coating is preferably based on an oxide or fluoride, particularly preferably on silicon dioxide, magnesium fluoride, or calcium fluoride, especially silicon dioxide (SiO₂). The silicon dioxide may be doped, for example, with aluminum (SiO₂:Al), boron (SiO₂:B), titanium (SiO₂:Ti), or zirconium (SiO₂:Zr).

[0047] The dielectric upper anti-reflective coating has an anti-reflective effect, thus reducing reflections at the coated lens surface and increasing light transmission through the lens. It also promotes a neutral color impression.

[0048] The thickness of the dielectric top anti-reflective layer is preferably from 20 nm to 200 nm, particularly preferably from 30 nm to 100 nm, and most preferably from 30 nm to 60 nm or even from 30 nm to 50 nm. This results in good anti-reflective properties and neutral coloration. The optical thickness of the dielectric top anti-reflective layer is preferably from 25 nm to 300 nm, particularly preferably from 40 nm to 450 nm, and most preferably from 40 nm to 90 nm or even from 40 nm to 75 nm.

[0049] In an advantageous embodiment, the emissivity-reducing coating comprises a dielectric lower anti-reflective layer arranged between the glass pane and the electrically conductive layer. The dielectric lower anti-reflective layer forms the aforementioned lower dielectric layer or is part of the aforementioned lower dielectric layer sequence. Starting from the surface of the glass pane, the emissivity-reducing coating then comprises, in the specified order:

[0050] - the dielectric lower anti-reflective coating,

[0051] - the electrically conductive layer,

[0052] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0053] - the DLC layer,

[0054] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0055] The refractive index of the dielectric lower anti-reflective coating is preferably at most 1.6 (i.e., less than or equal to 1.6), and particularly preferably from 1.3 to 1.6. The dielectric lower anti-reflective coating is preferably based on an oxide or fluoride, particularly preferably on silicon dioxide, magnesium fluoride, or calcium fluoride, and especially on silicon dioxide (SiO₂). The silicon dioxide may be doped, for example, with aluminum (SiO₂:Al), boron (SiO₂:B), titanium (SiO₂:Ti), or zirconium (SiO₂:Zr).

[0056] The dielectric lower anti-reflective layer reduces reflections on the coated glass surface, improves light transmission, and promotes a neutral color appearance. It has also been shown that the dielectric lower anti-reflective layer improves the coating's flexibility, particularly when based on silicon oxide. The coating can then be applied to the initially flat glass pane and bent along with the pane without cracking. The inventors hypothesize that this is due, in part, to the dielectric lower anti-reflective layer providing a relatively soft substrate for the electrically conductive layer, thus minimizing the build-up of critical stresses during bending.Secondly, the dielectric lower anti-reflective coating protects the electrically conductive layer from the diffusion of alkali ions from the glass pane, which are effectively absorbed by the dielectric lower anti-reflective coating. This can be advantageous even if a blocking layer is used to prevent alkali diffusion, through which residual alkali ions can still pass, as these are then captured by the dielectric lower anti-reflective coating.

[0057] The thickness of the dielectric lower anti-reflective layer is preferably from 5 nm to 50 nm, particularly preferably from 10 nm to 40 nm, for example from 15 nm to 30 nm. This results in good anti-reflective properties, neutral coloration, and good flexibility. The optical thickness of the dielectric lower anti-reflective layer is preferably from 7 nm to 75 nm, particularly preferably from 15 nm to 60 nm.

[0058] In an advantageous embodiment, the emissivity-reducing coating comprises a dielectric barrier layer for regulating oxygen diffusion, which is arranged between the electrically conductive layer and the dielectric upper anti-reflective layer. Starting from the surface of the glass pane, the emissivity-reducing coating then comprises, in the following order:

[0059] - optionally (and preferably) the dielectric lower anti-reflective layer, - the electrically conductive layer,

[0060] - the dielectric barrier layer for regulating oxygen diffusion,

[0061] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0062] - the DLC layer,

[0063] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0064] The refractive index of the dielectric barrier layer is preferably at least 1.9 (i.e. greater than or equal to 1.9), particularly preferably from 1.9 to 2.5.

[0065] The dielectric barrier layer is preferably based on a nitride or a carbide. For example, the dielectric barrier layer can be based on a nitride or carbide of tungsten, niobium, tantalum, zirconium, hafnium, chromium, titanium, silicon, or aluminum. In a preferred embodiment, the dielectric barrier layer is based on silicon nitride or silicon carbide, in particular silicon nitride (SisN^), with which particularly good results are achieved. The silicon nitride can be doped and, in a preferred further development, is doped with aluminum (SisN^Al), with zirconium (SisN^Zr), with titanium (SisN^Ti), or with boron (SisN^B).

[0066] During heat treatment after application of the coating according to the invention, the silicon nitride can be partially oxidized. The silicon nitride in the final product is therefore optionally partially oxidized. A dielectric barrier layer deposited as SisN4 then contains Si after heat treatment. x N y O z , where the oxygen content typically ranges from 0 atomic % to 35 atomic %.

[0067] It has been shown that the oxygen content of the TCO layer has a significant influence on its properties, particularly its transparency and conductivity. The manufacturing of the disc typically involves a heat treatment, such as a thermal prestressing process and / or a bending process, during which oxygen can diffuse to the TCO layer and oxidize it. The dielectric barrier layer serves to regulate the oxygen supply to an optimal level.

[0068] The thickness of the dielectric barrier layer is preferably from 5 nm to 30 nm, particularly preferably from 5 nm to 20 nm, and especially from 5 nm to 10 nm, for example from 5 nm to 9 nm or from 8 nm to 10 nm. This allows for particularly advantageous control of the oxygen content of the TCO layer. The thickness of the dielectric barrier layer is selected with regard to oxygen diffusion, rather than with regard to the optical properties of the disk. However, it has been shown that dielectric barrier layers with thicknesses in the specified range are compatible with the emissivity-reducing coating according to the invention and its optical requirements. The optical thickness of the dielectric barrier layer is preferably from 10 nm to 60 nm, particularly preferably from 10 nm to 40 nm, and most preferably from 10 nm to 20 nm.

[0069] In an advantageous embodiment, the emissivity-reducing coating comprises a dielectric blocking layer to prevent alkali diffusion, which is arranged between the glass pane and the electrically conductive layer. If a dielectric lower anti-reflective coating is present, the dielectric blocking layer is arranged below the dielectric lower anti-reflective coating. The dielectric blocking layer is thus arranged between the glass pane and the electrically conductive layer, or, if present, between the glass pane and the dielectric lower anti-reflective coating.

[0070] The dielectric blocker layer forms the aforementioned lower dielectric layer or is part of the aforementioned lower dielectric layer sequence. Starting from the surface of the glass pane, the emissivity-reducing coating then comprises, in the specified order:

[0071] - the dielectric blocker layer,

[0072] - optionally (and preferably) the dielectric lower anti-reflective coating,

[0073] - the electrically conductive layer,

[0074] - optionally (and preferably) the dielectric barrier layer to regulate oxygen diffusion,

[0075] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0076] - the DLC layer,

[0077] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0078] The refractive index of the dielectric blocker layer is preferably at least 1.9 (i.e., greater than or equal to 1.9), and particularly preferably from 1.9 to 2.5. The dielectric blocker layer is preferably based on an oxide, a nitride, or a carbide, preferably tungsten, chromium, niobium, tantalum, zirconium, hafnium, titanium, silicon, or aluminum, for example, oxides such as WO3, Nb2Os, Bi2Os, TiÜ2, Ta2Os, ZrÜ2, HfO2SnÜ2, or ZnSnOx, or nitrides such as Aln or SiN^. The blocker layer is particularly preferably based on silicon nitride (SisN^), with which particularly good results are achieved. The silicon nitride can be doped with, for example, aluminum (SisN^Al), titanium (SisN^Ti), zirconium (SisN^Zr), or boron (SisN^B).

[0079] During heat treatment after the application of the coating according to the invention, the silicon nitride can be partially oxidized. The silicon nitride in the final product is therefore optionally partially oxidized. A blocker layer deposited as SisN4 then contains Si after heat treatment. x N y O z , where the oxygen content typically ranges from 0 atomic % to 35 atomic %.

[0080] The dielectric blocker layer reduces or prevents the diffusion of alkali ions from the glass pane into the coating system. Alkali ions can negatively affect the properties of the coating. Furthermore, the dielectric blocker layer contributes advantageously to adjusting the optical properties of the overall coating structure. The dielectric blocker layer is preferably the bottom layer of the coating stack, thus having direct contact with the surface of the glass pane, where it can exert its optimal effect.

[0081] The thickness of the dielectric blocking layer is preferably from 10 nm to 50 nm, particularly preferably from 10 nm to 40 nm, for example from 20 nm to 35 nm, and most preferably from 10 nm to 30 nm, for example from 20 nm to 30 nm. This is advantageous with regard to the blocking effect against alkali diffusion and the optical properties of the window pane. The optical thickness of the dielectric blocking layer is preferably from 20 nm to 100 nm, particularly preferably from 20 nm to 80 nm, for example from 40 nm to 70 nm, and most preferably from 20 nm to 60 nm, for example from 40 nm to 60 nm.

[0082] The emissivity-reducing coating therefore comprises, starting from the surface of the glass pane, in the following order:

[0083] - optional (and preferred) the dielectric blocker layer,

[0084] - optionally (and preferably) the dielectric lower anti-reflective coating,

[0085] - the electrically conductive layer, - optionally (and preferably) the dielectric barrier layer for regulating oxygen diffusion,

[0086] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0087] - the DLC layer,

[0088] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0089] In one embodiment of the invention, the emissivity-reducing coating comprises, starting from the surface of the glass pane, in the specified order:

[0090] - optional (and preferred) the dielectric blocker layer,

[0091] - optionally (and preferably) the dielectric lower anti-reflective coating,

[0092] - the electrically conductive layer,

[0093] - the dielectric barrier layer for regulating oxygen diffusion,

[0094] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0095] - the DLC layer,

[0096] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0097] In a further embodiment of the invention, the emissivity-reducing coating comprises, starting from the surface of the glass pane, in the specified order:

[0098] - the dielectric blocker layer,

[0099] - optionally (and preferably) the dielectric lower anti-reflective coating,

[0100] - the electrically conductive layer,

[0101] - the dielectric barrier layer for regulating oxygen diffusion,

[0102] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0103] - the DLC layer,

[0104] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0105] In a particularly advantageous embodiment, the emissivity-reducing coating comprises all of the layers described above. Starting from the surface of the glass pane, the emissivity-reducing coating then comprises, in the following order:

[0106] - the dielectric blocking layer against alkali diffusion,

[0107] - the dielectric lower anti-reflective coating,

[0108] - the electrically conductive layer,

[0109] - the dielectric barrier layer for regulating oxygen diffusion,

[0110] - the dielectric upper anti-reflective coating with a refractive index of at most 1.6,

[0111] - the DLC layer,

[0112] the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0113] In a first particularly preferred embodiment, the coating consists only of the described layers and contains no further layers. The DLC layer is then the uppermost layer of the coating. It is then the layer furthest from the surface of the glass pane and is the final layer of the layer stack, which is exposed, visible, and accessible to people.

[0114] Structurally, a window pane can consist solely of the glass pane with the remissivity-reducing coating (single glazing). However, it is possible for the window pane to comprise another pane (or even several more panes) bonded to the coated glass pane in the manner of insulating glass or a laminated pane.

[0115] The window pane is designed to separate an interior space from the exterior environment within a window opening (for example, in a building or vehicle). The glass pane (and any additional panes of the window pane) has an outer surface and an interior surface, with a circumferential edge running between them. For the purposes of this invention, the outer surface refers to the main surface intended to face the exterior environment when installed. The interior surface refers to the main surface intended to face the interior space when installed.

[0116] In a preferred embodiment, the emissivity-reducing coating is applied to the interior surface of the glass pane. This interior surface of the glass pane is particularly preferably also the interior surface of the entire window pane that faces the interior. The emissivity-reducing coating can then exert its optimal effect because it is positioned between the window pane and the interior space it defines, and can thus act on all the thermal radiation emanating from the window pane.

[0117] Alternatively, the emissivity-reducing coating can also be arranged on the outer surface of the glass pane, which is then preferably also the outer surface of the entire window pane exposed to the external environment.

[0118] The window pane according to the invention is preferably a vehicle window, for example a windshield, side window, roof window, or rear window of a vehicle. The window pane is preferably designed either as a monolithic glass pane (structurally formed only from the coated glass pane, which is then preferably thermally tempered) or as a laminated pane, wherein the glass pane is bonded to another pane via a thermoplastic layer. However, the window pane can also be used in architectural applications, for example as a window or door pane of a building or interior space, or as a glass facade.

[0119] In a first embodiment, the window pane according to the invention is a monolithic glass pane (single pane) and is structurally formed solely from the glass pane with the emissivity-reducing coating. The glass pane is preferably prestressed, in particular thermally prestressed, to improve stability and fracture resistance and to minimize the risk of injury in the event of breakage. Such a single pane can be used, for example, as a window pane in vehicles (especially as a side window or rear window, but also as a roof window) or as a window pane in building-like structures, such as garden sheds, agricultural buildings (like barns), or hunting structures (like hunting blinds).

[0120] The glass pane preferably has a thickness of 2 mm to 10 mm, in particular 3 mm to 6 mm.

[0121] In a second embodiment, the window pane is designed as a laminated pane. In this configuration, the surface of the glass pane facing away from the emissivity-reducing coating is bonded to another glass pane via a thermoplastic interlayer. Such a laminated pane can be used particularly well as a vehicle window (for example, as a windshield or roof window, but also as a side window or rear window). Alternatively, the laminated pane can also be used as a standalone window pane in building-like structures, such as garden sheds, agricultural buildings (like barns), or hunting structures (like hunting blinds), or as part of an insulating glass unit as a window, door, or facade pane of a building. The laminated pane can also be used, for example, as an oven door or refrigerator door, or as a component thereof.

[0122] The glass pane with the emissivity-reducing coating preferably forms the inner pane of the laminated glass unit, while the other glass pane forms the outer pane. The window pane is intended to separate the interior (for example, of a building or vehicle) from the external environment within a window opening. For the purposes of this invention, the term "inner pane" refers to the glass pane facing the interior. The term "outer pane" refers to the glass pane facing the external environment.

[0123] The invention therefore also includes a composite pane, which comprises a further glass pane (in particular as an outer pane) and the glass pane according to the invention with the emissivity-reducing coating (in particular as an inner pane), which are connected to each other via a thermoplastic intermediate layer, wherein the emissivity-reducing coating is arranged on the surface of the glass pane facing away from the thermoplastic intermediate layer.

[0124] The two glass panes preferably each have a thickness of 0.5 mm to 5 mm, in particular 1 mm to 3 mm.

[0125] The thermoplastic interlayer contains at least one thermoplastic polymer, preferably ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or mixtures, copolymers, or derivatives thereof, particularly preferably PVB. The thermoplastic interlayer is typically formed from at least one thermoplastic film (bonding film), especially one based on PVB, EVA, or PU. This means that the film consists largely of the aforementioned polymer (proportion greater than 50 wt.%). The film may contain other additives besides the polymer, particularly plasticizers. The thickness of the thermoplastic interlayer is preferably from 0.2 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm.

[0126] In a further advantageous embodiment, the surface of the additional glass pane (especially the outer pane) facing the thermoplastic intermediate layer is provided with a solar control coating. A solar control coating reflects infrared components of solar radiation and can therefore reduce the heating of the window pane (and thus its emissivity) as well as the heating of the interior due to direct sunlight.

[0127] The sunscreen coating preferably contains at least one IR-reflective layer based on a metal, i.e., a metallic layer, particularly one based on silver. The IR-reflective layer preferably contains at least 90 wt.% silver, more preferably at least 99 wt.% silver, and most preferably at least 99.9 wt.% silver. The silver layer may contain dopants, for example, palladium, gold, copper, or aluminum. The thickness of the silver layer is typically from 5 nm to 20 nm.

[0128] In addition to the metallic layer, dielectric layers or layer sequences are typically present. These dielectric layers or layer sequences are also referred to as dielectric layer modules. The solar control coating comprises n metallic layers and (n+1) dielectric layer modules, with the dielectric layer modules and the metallic layers arranged alternately, such that each metallic layer is positioned between two dielectric layer modules and one layer module is positioned between adjacent metallic layers. The number n is a natural number greater than or equal to 1 (n > 1).

[0129] In a preferred embodiment, the solar control coating has at least two metallic layers (n > 2), for example, exactly two metallic layers (n = 2), or even at least three metallic layers (n > 3), for example, exactly three metallic layers (n = 3). A plurality of metallic layers improves the IR-reflecting effect without excessively reducing light transmission, because the individual metallic layers can be made thinner. On the other hand, the number of metallic layers should not be too large in order to keep production costs low. The layer modules can be configured independently of one another as single dielectric layers or as sequences of dielectric layers (i.e., a plurality of successive dielectric layers). Common dielectric layers of such a thin-film stack include, for example:

[0130] Anti-reflective coatings, which reduce the reflection of visible light and thus increase the transparency of the coated disc, for example based on silicon nitride (SisN^, silicon-metal mixed nitrides such as silicon zirconium nitride (SiZrN), titanium oxide (TiCh), aluminum nitride (AlN) or tin oxide (ZnO), with layer thicknesses of, for example, 10 nm to 100 nm;

[0131] - Matching layers that improve the crystallinity of the electrically conductive layer, for example based on zinc oxide (ZnO), with layer thicknesses of, for example, 3 nm to 20 nm;

[0132] Smoothing layers that improve the surface structure for the layers above, for example based on a non-crystalline oxide of tin, silicon, titanium, zirconium, hafnium, zinc, gallium and / or indium, in particular based on tin-zinc mixed oxide (ZnSnO), with layer thicknesses of, for example, 3 nm to 20 nm.

[0133] The sun protection coating can optionally include blocker layers that protect the metallic layers from degradation. Blocker layers are typically very thin, metal-containing layers based on niobium, titanium, nickel, chromium, zirconium, or alloys thereof, with layer thicknesses of, for example, 0.1 nm to 0.5 nm.

[0134] The solar control coating is preferably applied to the entire surface of the glass pane, with the exception of a perimeter border and, optionally, a local area intended to ensure the transmission of electromagnetic radiation through the pane as a communication, sensor, or camera window, and which is therefore not coated with the solar control coating. The perimeter uncoated border, for example, has a width of up to 20 cm. It prevents direct contact between the solar control coating and the surrounding atmosphere, thus protecting the solar control coating inside the laminated glass pane from corrosion and damage. Preferably, at least 80% of the glass surface is coated with the solar control coating.

[0135] The sun protection coating can also be embedded in the thermoplastic intermediate layer instead of being applied to the surface of the outer pane, for example applied to a carrier film (preferably based on PET) which is inserted between two thermoplastic connecting films.

[0136] In a third embodiment, the window pane is designed as an insulating glass unit. The glass pane according to the invention, with its emissivity-reducing coating in the edge region, is connected to another glass pane via a frame-like spacer, so that a cavity is formed between the two panes. This cavity is typically filled with inert gas. The emissivity-reducing coating is preferably arranged on the surface of the glass pane facing away from the spacer. The glass pane with the emissivity-reducing coating preferably forms the inner pane of the insulating glass unit, while the other glass pane forms the outer pane. Here, too, it is possible for the other glass pane to be equipped with a solar control coating of the type described above, preferably on its surface facing the spacer.Such insulating glass units can be used, for example, as window, door, or facade (glass facade) panes in a building. The insulating glass unit can also be used, for example, as an oven door or refrigerator door. The two glass panes preferably each have a thickness of 1 mm to 10 mm, particularly 3 mm to 8 mm.

[0137] The window pane can be flat, as is common in architecture or in the windows of buses, trains, or tractors. However, in a more advantageous design, the window pane is curved, as is typical for automotive windows. Typical radii of curvature range from approximately 10 cm to approximately 40 m.

[0138] The glass pane is preferably made of glass, in particular soda-lime glass, which is common for window panes. However, the glass pane can also be made of other types of glass (for example, borosilicate glass, quartz glass, aluminosilicate glass). The same applies to any additional glass pane that may be part of the window pane according to the invention.

[0139] The window pane according to the invention is preferably transparent, so that at least some visibility through the window pane is possible. However, the degree of this visibility depends very much on the specific application of the window pane. For example, high light transmission is common or even legally required for window panes in architectural applications and for certain vehicle windows (especially windshields and front side windows). In these cases, the light transmission of the window pane is preferably greater than 70%. For other vehicle windows (especially roof windows, rear windows, and rear side windows), a strong tint is sometimes common. In these cases, the light transmission of the window pane is preferably greater than 2% and, for example, less than 30% or even less than 10%. The term light transmission (total transmission) refers to that defined by ECE-R 43, Annex 3, Section 9.1. Specified procedures for testing the light transmission of motor vehicle windows. Tinting can be achieved by tinting or coloring the glass pane with the emissivity-reducing coating – in the case of laminated windows, alternatively or additionally by tinting or coloring the other glass pane and / or the thermoplastic interlayer.

[0140] The window pane according to the invention with an emissivity-reducing coating is particularly preferably heat-treated, i.e., during the manufacture of the window pane according to the invention with an emissivity-reducing coating, a heat treatment was particularly preferably carried out.

[0141] The invention also includes a method for manufacturing a window pane according to the invention. The method comprises at least the following steps:

[0142] A) Providing a pane of glass,

[0143] B) Applying an emissivity-reducing coating comprising an electrically conductive layer based on a transparent conductive oxide, a dielectric top anti-reflective layer with a refractive index of not more than 1.6 and a DLC layer to a surface of the glass pane,

[0144] C) Application of a temperature protection layer based on magnesium or germanium to the DLC layer of the emissivity-reducing coating,

[0145] D) Performing a heat treatment, preferably at a temperature of 300°C to 800°C,

[0146] E) Washing off the thermal protection layer.

[0147] According to the invention, in the emissivity-reducing coating, the dielectric upper anti-reflective layer is arranged directly adjacent to the DLC layer.

[0148] In a preferred embodiment of the method, step D) comprises bending and / or tempering the coated glass pane obtained in step C). In this way, heat-treated window panes according to the invention with an emissivity-reducing coating can be produced.

[0149] The tempering protection layer, which is designed as a removable protective layer, can protect the underlying layers, in particular the minimum DLC layer of the emissivity-reducing coating, from degradation and corrosion during heat treatment, such as a common bending process for glass panes in the automotive sector, tempering or lamination to produce a composite pane.

[0150] In a preferred embodiment, the removable heat-resistant layer is a germanium-based or magnesium-based layer. Such heat-resistant layers and their production are disclosed, for example, in WO 2023 / 275493 A1.

[0151] The thermal protection layer can have a thickness of 1 nm to 25 nm, preferably between 2 nm and 20 nm, particularly preferably between 5 nm and 15 nm.

[0152] The removal of the heat protection layer in step E) can be done with water without the use of solvents and without the use of mechanical friction.

[0153] Cutting the glass pane to its final dimensions can be done before or after coating.

[0154] The electrically conductive layer of the emissivity-reducing coating, the dielectric upper anti-reflective layer, and—if present—the lower dielectric layer or layer sequence and / or the dielectric barrier layer are preferably applied to the respective glass surface by physical vapor deposition (PVD), particularly preferably by sputtering, and most preferably by magnetron sputtering. However, the coatings can also be applied, for example, by chemical vapor deposition (CVD), such as plasma-enhanced chemical vapor deposition (PECVD), by evaporation, or by atomic layer deposition (ALD). The same applies to any solar control coating on another glass pane that forms part of the window pane.The diamond-like carbon (DLC) layer of the emissivity-reducing layer is preferably produced by a combined plasma-enhanced chemical vapor deposition (PECVD) / magnetron process (magnetron-PECVD process). Such a process is described, for example, in WO 2019 / 020481 A1. This process step comprises coating with a diamond-like carbon (DLC) layer by a PECVD process with plasma generation via a magnetron target (magnetron-PECVD) in a vacuum chamber in which the magnetron equipped with the target and a glass plate pre-coated with the other layers of the emissivity-reducing layer are arranged. The process includes introducing at least one reactant gas into the plasma generated by the magnetron target in the vacuum chamber, thereby forming fragments of the reactant gas which are deposited on the pre-coated glass plate to form the DLC layer.The coating process is also suitable for large-area coating of glass panes, for example, vehicle windshields with a DLC layer. The resulting DLC ​​layer exhibits excellent quality in terms of scratch resistance and appearance. The coating step can advantageously be carried out using conventional deposition equipment. Preferably, acetylene or methane is used as the reactant gas, along with a DC, AC-MF, or HiPIMS power source, or HiPIMS with a carbon target.

[0155] If the window pane is to be curved, step D) includes a bending process. If the window pane is a laminated pane, the outer and inner panes are preferably bent congruently together (i.e., simultaneously and using the same tool), because this ensures that the shape of the panes is optimally matched for subsequent lamination. Typical temperatures for glass bending processes are, for example, 500°C to 700°C.

[0156] If the window pane is a laminated pane, the glass pane is bonded to the other glass pane via the thermoplastic interlayer. This is achieved using methods known per se, such as autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The bonding of the glass panes typically occurs under the influence of heat, vacuum, and / or pressure. Lamination preferably takes place after a glass bending process. The preferred embodiments of the window pane with an emissivity-reducing coating described above also apply accordingly to the inventive process.

[0157] The invention further comprises the use of a window pane according to the invention in buildings or in means of transport on land, water, or in the air. Its use as a vehicle window, for example as a windshield, side window, roof window, or rear window, particularly as a vehicle roof window, is preferred. The vehicle is, for example, an airplane or helicopter, a ship, a rail vehicle, or a motor vehicle, such as a passenger car, a truck, a bus, or an agricultural or construction vehicle, with motor vehicles being preferred.

[0158] The invention is explained in more detail below with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way.

[0159] They show:

[0160] Fig. 1 shows a cross-section through an embodiment of the window pane according to the invention with a scratch-resistant, emissivity-reducing coating,

[0161] Fig. 2 is an enlarged view of section Z from Figure 1 ,

[0162] Fig. 3 shows an enlarged view of a section of a further embodiment of the window pane according to the invention with a scratch-resistant, emissivity-reducing coating.

[0163] Fig. 4 shows an enlarged view of a section of a further embodiment of the window pane according to the invention with a scratch-resistant, emissivity-reducing coating.

[0164] Fig. 5 shows a cross-section through a further embodiment of the window pane according to the invention with an emissivity-reducing coating, and

[0165] Fig. 6 shows a flowchart of an embodiment of the method according to the invention.

[0166] Figures 1 and 2 each show a detail of a window pane according to the invention. This is a monolithic glass pane (single pane) structurally formed from a single glass pane 2. The glass pane 2 is made of soda-lime glass and has, for example, a thickness of 3.5 mm. The glass pane 2 is provided with an emissivity-reducing coating 10. The window pane is used, for example, as a side window of a motor vehicle. It is typically curved, although for the sake of simplicity it is shown flat in the figure. The emissivity-reducing coating 10 is applied to the interior surface of the glass pane 2, which, in its installed position, faces the vehicle interior. This interior surface is typically concave, while the opposite exterior surface is convex.

[0167] The emissivity-reducing coating 10 is designed and intended to reflect the heat radiation emitted by the heated glass pane 2 at high outside temperatures, thereby reducing the heating of the vehicle interior. At low outside temperatures, it reduces the radiation of heat from the vehicle interior. The emissivity-reducing coating 10 thus improves thermal comfort in the vehicle interior. Furthermore, the emissivity-reducing coating 10 is scratch-resistant.

[0168] The emissivity-reducing coating 10, in the embodiment shown in detail in Fig. 2, consists, starting from the surface of the glass pane 2, in the specified order as follows:

[0169] - an electrically conductive layer 13 based on a TCO,

[0170] - a dielectric upper anti-reflective coating 15 with a refractive index of at most 1.6 and

[0171] - a DLC layer 16.

[0172] The electrically conductive layer 13, for example, is made of indium tin oxide (ITO) and has a thickness of, for example, 72 nm.

[0173] The dielectric upper anti-reflective layer 15, for example, is made of silicon oxide (SiÜ2) and has a thickness of, for example, 50 nm. Its refractive index is 1.45.

[0174] For example, DLC layer 16 has a thickness of 5 nm.

[0175] Fig. 3 shows an enlarged view of a section of a further embodiment of the window pane according to the invention. The embodiment of the window pane according to the invention shown in Fig. 3 differs from the embodiment shown in Figs. 1 and 2 only in that the emissivity-reducing coating 10 additionally comprises a dielectric blocker layer 11 against alkali diffusion with a refractive index of at least 1.9 and a dielectric lower anti-reflective coating 12 with a refractive index of at most 1.6. In the embodiment shown in Fig. 3, the emissivity-reducing coating 10 consists, starting from the surface of the glass pane, of the following in the specified order:

[0176] - a dielectric blocker layer 11 against alkali diffusion with a refractive index of at least 1.9,

[0177] - a dielectric lower anti-reflective layer 12 with a refractive index of at most 1.6,

[0178] - an electrically conductive layer 13 based on a TCO,

[0179] - a dielectric upper anti-reflective coating 15 with a refractive index of at most 1.6, and

[0180] - a DLC layer 16.

[0181] The dielectric blocker layer 11, for example, is made of silicon nitride (SiS1) and has a thickness of, for example, 30 nm. Its refractive index is 2.0. The dielectric lower anti-reflective layer 12 is made of silicon oxide (SiO2) and has a thickness of, for example, 20 nm. Its refractive index is 1.45. The electrically conductive layer 13 is made of, for example, indium tin oxide (ITO) and has a thickness of, for example, 72 nm. The dielectric upper anti-reflective layer 15 is made of silicon oxide (SiO2) and has a thickness of, for example, 50 nm. Its refractive index is 1.45. The DLC layer 16 has a thickness of, for example, 5 nm.

[0182] Fig. 4 shows an enlarged view of a section of a further embodiment of the window pane according to the invention. The embodiment of the window pane according to the invention shown in Fig. 4 differs from the embodiment shown in Fig. 3 only in that the emissivity-reducing coating 10 additionally comprises a dielectric barrier layer 14 for regulating oxygen diffusion with a refractive index of at least 1.9. In the embodiment shown in Fig. 4, the emissivity-reducing coating 10 consists, starting from the surface of the glass pane, of the following in the specified order:

[0183] - a dielectric blocking layer 11 against alkali diffusion with a refractive index of at least 1.9, - a dielectric lower anti-reflective layer 12 with a refractive index of at most 1.6,

[0184] - an electrically conductive layer 13 based on a TCO,

[0185] - a dielectric barrier layer 14 for regulating oxygen diffusion with a refractive index of at least 1.9,

[0186] - a dielectric upper anti-reflective coating 15 with a refractive index of at most 1.6, and

[0187] - a DLC layer 16.

[0188] The dielectric blocker layer 11, for example, is made of silicon nitride (SiS1) and has a thickness of, for example, 30 nm. Its refractive index is 2.0. The dielectric lower anti-reflective layer 12, for example, is made of silicon oxide (SiO2) and has a thickness of, for example, 20 nm. Its refractive index is 1.45. The electrically conductive layer 13, for example, is made of indium tin oxide (ITO) and has a thickness of, for example, 72 nm. The dielectric barrier layer 14, for example, is made of silicon nitride (SiS1) and has a thickness of, for example, 9 nm. Its refractive index is 2.0. The dielectric upper anti-reflective layer 15 is made of silicon oxide (SiO2) and has a thickness of, for example, 50 nm. Its refractive index is 1.45. The DLC layer 16, for example, has a thickness of 5 nm.

[0189] For the sake of clarity, stoichiometric molecular formulas have been given for the oxides and nitrides used. This does not imply that the layers must necessarily be stoichiometric. They can be stoichiometric, substoichiometric, or superstoichiometric with respect to oxygen or nitrogen content.

[0190] Fig. 5 shows a further embodiment of the window pane according to the invention. The window pane is designed as a laminated pane consisting of a glass pane 2 with the emissivity-reducing coating 10, which functions as the inner pane, and an outer pane 1, which are connected to each other via a thermoplastic intermediate layer 3.

[0191] Glass pane 2 is made of soda-lime glass and has a thickness of, for example, 1.6 mm. The outer pane 1 is also made of soda-lime glass and has a thickness of, for example, 2.1 mm. The thermoplastic interlayer 3 is, for example, made of a PVB film with a thickness of 0.76 mm.

[0192] The emissivity-reducing coating 10 can, for example, be designed analogously to the embodiments shown in Fig. 2, Fig. 3 or Fig. 4.

[0193] The window pane is intended as a roof window for a vehicle. It is typically curved, although for simplicity it is shown flat in Fig. 5. The emissivity-reducing coating 10 is applied to the interior surface of the glass pane 2, which, in its installed position, faces the vehicle interior. This interior surface is typically concave.

[0194] In the embodiment shown in Fig. 5, the outer pane 1 is provided with a solar control coating 20, which is applied to its surface facing the thermoplastic intermediate layer 3. A circumferential edge region remains uncoated, so that the solar control coating 20 has no contact with the surrounding atmosphere. The solar control coating 20 is, for example, composed of three silver layers and four dielectric layer sequences arranged alternately. The solar control coating 20 reflects infrared components of solar radiation, thus reducing the heating of the window pane and the vehicle interior. It is understood that the solar control coating 20 is optional; the window pane according to the invention can also be designed as a laminated pane and not have a solar control coating 20.

[0195] Fig. 6 shows a flowchart of an embodiment of the method according to the invention. In a first step P1, a glass pane 2 is provided. In a subsequent second step P2, an emissivity-reducing coating 10 comprising an electrically conductive layer 13 based on a transparent conductive oxide, a dielectric upper anti-reflective layer 15 with a refractive index of at most 1.6, and a DLC layer 16 is applied to a surface of the glass pane 2. In a third step P3, a heat-protective layer based on magnesium or germanium is applied to the DLC layer 16 of the emissivity-reducing coating 10, wherein the dielectric upper anti-reflective layer 15 is arranged directly adjacent to the DLC layer 16. In a subsequent fourth step P4, a heat treatment is carried out, preferably at a temperature of 300 °C to 800 °C.In a subsequent fifth step P5, the thermal protection layer is washed off and a window pane according to the invention with a scratch-resistant, emissivity-reducing coating 10 is obtained.

[0196] Examples

[0197] Test discs were produced with a glass disc 2 made of soda-lime glass and an emissivity-reducing coating 10 deposited onto the glass disc 2. The layer thicknesses and materials of Examples 1 and 2 according to the invention, as well as of Comparative Example 1, before and after heat treatment, are given in Tables 1 and 2.

[0198] Table 1: Setup of examples 1 and 2 and of comparison example 1 before heat treatment.

[0199] Layer thickness

[0200] Material reference mark

[0201] Example 1 Example 2 Comparison example 1 MgAIZn 10.0 nm - - Ge - 20.0 nm - DLC 16 5.0 nm 5.0 nm - SiO215 50.0 nm 50.0 nm 50.0 nm

[0202] SisN4 14 9.0 nm - 9.0 nm

[0203] 10

[0204] ITO 13 72.0nm 72.0nm 72.0nm

[0205] SiO212 20.0nm 20.0nm 20.0nm

[0206] Si2N4 11 30.0nm 30.0nm 30.0nm

[0207] Lime soda 2 2.1 mm 2.1 mm 2.1 mm

[0208] Glass

[0209]

[0210] The germanium layer in Example 1 and the MgAIZn layer in Example 2 serve as a thermal protection layer. In contrast to Example 1 and Example 2, Comparison Example 1 has neither a DLC layer 16 nor a thermal protection layer.

[0211] The coated glass panes 2, as specified in Table 1, were subjected to a heat treatment for 8 minutes at 650°C. Subsequently, in examples 1 and 2, the oxide layer formed from the heat-resistant coating during the heat treatment was washed off, resulting in coated glass panes 2 with a structure as shown in Table 2. Table 2: Structure of examples 1 and 2 and of comparative example 1 after heat treatment and washing.

[0212] Layer thickness

[0213] Material reference mark

[0214] Example 1 Example 2 Comparison example 1

[0215] DLC 16 5.0nm 5.0nm - SiO215 50.0nm 50.0nm 50.0nm

[0216] SisN4 14 9.0 nm - 9.0 nm

[0217] 10

[0218] ITO 13 72.0nm 72.0nm 72.0nm

[0219] SiO212 20.0nm 20.0nm 20.0nm

[0220] Si2N4 11 30.0nm 30.0nm 30.0nm

[0221] Lime soda 2 2.1 mm 2.1 mm 2.1 mm

[0222] Glass

[0223]

[0224] The window panes according to Example 1 and Example 2, and the non-inventive window pane according to Comparative Example 1 with a structure as specified in Table 2, were subjected to a qualitative (comparative) test for scratch resistance. For this purpose, Examples 1 and 2 and the Comparative Example were subjected to an Elcometer test with a sealing lip for side windows, 10,000 cycles, dry condition, and an Erichsen Brush test, 5,000 cycles, wet condition. Subsequently, Examples 1 and 2, as well as Comparative Example 1, were visually inspected, and, in contrast to Examples 1 and 2 according to the invention, clear traces of coating abrasion were visible in the Comparative Example.

[0225] Furthermore, roughness measurements according to ISO 25178 were subsequently carried out on the window panes subjected to the Elcometer test and Erichsen brush test according to Example 1 and 2 and Comparative Example 1 using white light interferometry, and the roughness values ​​S given in Table 3 were obtained. a receive.

[0226] Table 3

[0227] Example 1 Example 2 Comparison example 1 Roughness value S a [nm] 2.0 5.2 7.1

[0228]

[0229] In examples 1 and 2 according to the invention, very good scratch resistance was achieved, with roughness values ​​of less than 6 nm. The optical properties of the window pane are determined by the totality of the layers and can be adjusted to the requirements of the application by varying the materials and layer thicknesses of the individual layers. Reference numeral list:

[0230] 1 outer pane

[0231] 2 glass panes

[0232] 3 thermoplastic intermediate layer

[0233] 10 emissivity-reducing coatings

[0234] 11 dielectric blocker layer against alkali diffusion

[0235] 12 dielectric lower anti-reflective coating

[0236] 13 Electrically conductive layer (TCO layer)

[0237] 14 Dielectric barrier layer for regulating oxygen diffusion 15 Dielectric upper anti-reflective layer

[0238] 16 DLC layers

[0239] 20 sun protection coating

[0240] Z enlarged section

Claims

1. Patent claims 1. Window pane with an emissivity-reducing coating, comprising at least a glass pane (2) and an emissivity-reducing coating (10) on a surface of the glass pane (2), 3. wherein the emissivity-reducing coating (10) comprises, starting from the surface of the glass pane (2), in the specified order, an electrically conductive layer (13) based on a transparent conductive oxide, a dielectric upper anti-reflective layer (15) with a refractive index of not more than 1.6 and a DLC layer (16), 4. wherein the dielectric upper antireflection layer (15) is arranged immediately adjacent to the DLC layer (16).

2. Window pane according to claim 1, wherein the thickness of the DLC layer (16) is from 1 nm to 20 nm, preferably from 2 nm to 10 nm, particularly preferably from 3 nm to 7 nm.

3. Window pane according to claim 1 or 2, wherein the transparent conductive oxide is indium tin oxide (ITO).

4. Window pane according to one of claims 1 to 3, wherein the electrically conductive layer (13) has a thickness of 30 nm to 150 nm, preferably of 50 nm to 130 nm.

5. Window pane according to one of claims 1 to 4, wherein the emissivity-reducing coating (10) comprises a dielectric lower anti-reflective coating (12) arranged between the glass pane (2) and the electrically conductive layer (13) with a refractive index of at most 1.6, preferably based on silicon oxide.

6. Window pane according to one of claims 1 to 5, wherein the emissivity-reducing coating (10) comprises a dielectric barrier layer (14) arranged between the electrically conductive layer (13) and the dielectric upper anti-reflective layer (15) for regulating oxygen diffusion with a refractive index of at least 1.9, preferably based on silicon nitride, which is optionally partially oxidized.

7. Window pane according to one of claims 1 to 6, wherein the emissivity-reducing coating (10) between the glass pane (2) and the electrically conductive layer (13), and optionally below the dielectric lower anti-reflective layer (12), comprises a dielectric blocker layer (11) against alkali diffusion with a refractive index of at least 1.9, preferably based on silicon nitride, which is optionally partially oxidized.

8. Window pane according to one of claims 1 to 7, wherein the dielectric upper anti-reflective layer (15) is based on silicon oxide.

9. Window pane according to one of claims 1 to 8, which is designed as a laminated pane, wherein the surface of the glass pane (2) facing away from the emissivity-reducing coating (10) is connected to an outer pane (1) via a thermoplastic intermediate layer (3).

10. Window pane according to claim 9, wherein the surface of the outer pane (1) facing the thermoplastic intermediate layer (3) is provided with a solar control coating (20) which contains at least one layer based on silver.

11. Method for manufacturing a window pane according to any one of claims 1 to 10, comprising at least the steps 14.A) Providing a glass pane (2), 15.B) Application of an emissivity-reducing coating (10) comprising an electrically conductive layer (13) based on a transparent conductive oxide, a dielectric upper anti-reflective layer (15) with a refractive index of not more than 1.6 and a DLC layer (16) on a surface of the glass pane (2), 16.C) Applying a temperature-protective layer based on magnesium or germanium to the DLC layer (16) of the emissivity-reducing coating (10), D) Performing a heat treatment, preferably at a temperature of 300°C to 800°C, 17.E) Washing off the thermal protection layer.

12. Method according to claim 11, wherein step D) comprises bending and / or tempering the coated glass sheet (2) obtained in step C).

13. Method according to claim 11 or 12, wherein the tempering protection layer has a layer thickness of 1 nm to 25 nm, preferably of 2 nm to 20 nm, particularly preferably of 5 nm to 15 nm.

14. Use of a window pane according to one of claims 1 to 10 in buildings or in means of transport on land, water or in the air, preferably as a vehicle window, in particular as a vehicle roof window.

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