Disc coated with an electrically conductive layer stack

Abstract

The present invention relates to a coated disc (100), comprising a substrate (1) and an electrically conductive layer stack (2) on a surface (IV) of the substrate (1), which, starting from the substrate (1), comprises at least: - a dielectric barrier layer (3) against ion diffusion with a refractive index of at least 1.9 and a layer thickness of 5 nm to 18 nm; - a dielectric anti-reflection layer (4) with a refractive index of at most 1.6; - an electrically conductive layer (5) with a layer thickness of 75 nm to 120 nm; - a dielectric blocker layer (6) for regulating oxygen diffusion with a refractive index of at least 1.9 and a layer thickness of 10 to 25 nm; and - a dielectric optical layer (7) with a refractive index of at most 1.6.

Description

[0001] Disc coated with electrically conductive layer stack

[0002] The invention relates to a coated pane with an electrically conductive layer stack, a composite pane comprising the coated pane, as well as the production of the coated pane and its use.

[0003] Glass panes with transparent, electrically conductive coatings are well known. This allows the glass panes to be given a function without significantly impairing visibility through the pane. Such coatings are used, for example, as heatable coatings or heat-reflecting coatings on window panes for vehicles or buildings.

[0004] The interior of a vehicle or building can heat up considerably in summer when ambient temperatures are high and exposed to intense direct sunlight. However, if the outside temperature is lower than the interior temperature, which is particularly common in winter, a cold window acts as a heat sink, which is perceived as unpleasant. The interior must also be heated to prevent cooling through the window panes.

[0005] Heat-reflecting coatings (so-called low-E coatings) reflect a significant portion of solar radiation, particularly in the infrared range, which reduces interior heating in summer. The coating also reduces the emission of long-wave thermal radiation from a heated window into the interior. It also reduces the radiation of heat from the interior to the outside environment during low outdoor temperatures in winter.

[0006] To be effective, the heat-reflecting coating must be applied to the interior surface of the pane, i.e., between the interior and the actual glass pane. There, the coating is exposed to the atmosphere, which precludes the use of corrosion-prone coatings, such as those based on silver. Coatings based on transparent conductive oxides (TCO), such as indium tin oxide (ITO), have proven suitable as electrically conductive coatings on exposed surfaces due to their corrosion resistance and good conductivity. Such coatings are known, for example, from EP 2 141 135 A1, WO 2010115558 A1, and WO 2011105991 A1.WO2018206236A1 discloses a composite pane with an electrically conductive layer having reflective properties with respect to thermal radiation, wherein fingerprints on the electrically conductive layer are less visible due to a special layer structure.

[0007] WO2013132176A2 shows a glazing unit for the building sector with an electrically conductive layer based on ITO, wherein the coating serves in particular to reduce the condensation of moisture on the glazing unit.

[0008] WO2015055944A1 describes a process for applying coatings comprising transparent oxides to a substrate.

[0009] WO2019106264A1 describes a substrate coated with a low-E layer in conjunction with a bismuth-based cover print, wherein the cover print has good adhesion to the low-E layer.

[0010] Windows with a low-E coating must meet various other requirements in addition to thermal criteria. One problem with coating windows is compatibility with other coatings, particularly screen printing. Screen printing is typically applied to the window in the automotive sector. If the entire surface of a window has been pre-coated with a low-E coating, problems with the adhesion of the screen print to the window can arise. This can also lead to reduced scratch resistance of the black print. The low-E coating should also be stable, i.e., chemically inert, at high temperatures. High temperatures are used, for example, in the bending process of windows.

[0011] Another common problem that occurs with low-E coatings in conjunction with windows, especially tinted windows, is increased light reflection and viewing-angle-dependent tinting of the window due to the coating. High reflection and tinting of the window can be distracting or aesthetically disturbing for the viewer, which can also pose a safety risk, especially when used as a vehicle windscreen. For generic windows, color neutrality and light reflection are reciprocally related. This means that the coated window exhibits lower light reflection, but a stronger tint, and vice versa.

[0012] The present invention is based on the object of providing a coated pane with a heat radiation insulating effect, which additionally has a higher color neutrality and a lower light reflection, in particular at higher angles of incidence.

[0013] The object of the present invention is achieved by a coated pane according to claim 1. Preferred embodiments are evident from the subclaims.

[0014] The wafer according to the invention comprises a substrate and an electrically conductive layer stack on a surface of the substrate. Starting from the substrate, the layer stack comprises, in the following order:

[0015] - a dielectric barrier layer against ion diffusion with a refractive index of at least 1.9 and a layer thickness of 5 nm to 18 nm,

[0016] - a dielectric anti-reflective coating with a refractive index of not more than 1.6,

[0017] - an electrically conductive layer with a thickness of 75 to 120 nm,

[0018] - a dielectric blocking layer for regulating oxygen diffusion with a refractive index of at least 1.9 and a layer thickness of 10 to 25 nm and

[0019] - a dielectric optical layer with a refractive index of not more than 1.6.

[0020] The invention is based on the finding that layers with emissivity-reducing properties generally have high reflection properties in the visible light spectrum and / or high color intensity. However, high reflection and / or color intensity can be perceived as irritating and disturbing by users. It can also pose a safety risk if, for example, light is reflected too strongly on a car window or traffic signs outside the car are incorrectly perceived (e.g. a red sign takes on a greenish-reddish hue when viewed through the window). The tint of the window depends on the viewing angle. In particular, shallow viewing angles of 60° to 85° to the surface of the window lead to strong coloration when viewed through or reflected.These flat viewing angles are particularly common in windshields (flat installation angle) and roof windows (flat viewing angle for rear passengers) in vehicles. The inventors discovered that the dominant color component, which is largely responsible for the visually strongly perceptible coloration in generically coated windows, is due to high positive a* values ​​of the LAB color space. High positive a* values ​​result in a red tint on the window in visual perception.

[0021] The electrically conductive layer stack according to the invention is a coating that reflects heat radiation. Such a layer stack is often also referred to as a low-E coating, low-emissivity coating, or emissivity-reducing coating. Its function is to prevent heat radiation from entering the interior (IR components of solar radiation and, in particular, the thermal radiation from the window itself) and also to prevent heat radiation from escaping the interior. In principle, however, the layer stack can also fulfill other functions, for example, as a heatable coating when electrically contacted, so that it is heated by an electric current flow.

[0022] The pane according to the invention is preferably a window pane and is intended to separate the interior from the external environment in an opening, for example in a vehicle or a building. The surface of the substrate on which the layer stack according to the invention is arranged is preferably the interior-side surface of the pane or substrate. For the purposes of the invention, the interior-side surface is understood to be the surface which is intended to face the interior when the pane is in the installed position. This is particularly advantageous with regard to thermal comfort in the interior. At high outside temperatures and in sunlight, the layer stack according to the invention can particularly effectively reflect at least partially the thermal radiation radiated by the entire pane towards the interior.At low outside temperatures, the layer stack can effectively reflect the heat radiation emitted from the interior, thus reducing the effect of the cold pane as a heat sink. Typically, the surfaces of a glazing unit are numbered from outside to inside, so that the interior-facing surface is designated "Side 2" for single-pane glazing and "Side 4" for double-pane glazing (e.g., laminated glass or insulating glass). Alternatively, the layer stack can also be arranged on the exterior surface of the substrate. This can be particularly useful in the architectural field, for example, as an anti-condensation coating on a window pane.

[0023] Alternatively, the layer stack can also fulfill other functions, for example as an electrically based capacitive or resistive sensor for tactile applications such as touch screens or touch panels.

[0024] The layer stack is a sequence of thin layers (layer structure, layer stack). While the electrical conductivity is ensured by the at least one electrically conductive layer, the optical properties, in particular the transmission and reflectivity, are significantly influenced by the remaining layers and can be specifically adjusted through their design. So-called anti-reflective coatings and optical layers, which have a lower refractive index than the electrically conductive layer and are arranged both above and below it, have a particular influence in this context. The anti-reflective coatings, which interact with optical layers, can increase the transmission through the pane and reduce the reflectivity, particularly as a result of interference effects. The effect depends crucially on the refractive index and layer thickness.In an advantageous embodiment, the layer stack comprises at least one anti-reflective layer below and at least one optical layer above the electrically conductive layer. The anti-reflective layer and the optical layer each have a lower refractive index than the electrically conductive layer (refractive index of at most 1.6, in particular of at most 1.5).

[0025] The layer stack according to the invention is transparent, meaning it does not noticeably restrict the view through the substrate. The absorption of the layer stack is preferably from about 1% to about 20% in the visible spectral range. The visible spectral range is understood to be the spectral range from 380 nm to 780 nm.

[0026] If a first layer is arranged above a second layer, this means, within the meaning of the invention, that the first layer is arranged further away from the substrate than the second layer. If a first layer is arranged below a second layer, this means, within the meaning of the invention, that the second layer is arranged further away from the substrate than the first layer. If a first layer is arranged above or below a second layer, this does not necessarily mean, within the meaning of the invention, that the first and second layers are in direct contact with one another. One or more further layers can be arranged between the first and second layers, unless this is explicitly excluded.

[0027] The layer stack is typically applied over the entire surface of the substrate, possibly with the exception of a peripheral edge region and / or other locally limited areas that can be used, for example, for data transmission. The coated portion of the substrate surface is preferably at least 80%, in particular at least 90%.

[0028] If a layer or other element contains at least one material, this includes, within the meaning of the invention, the case where the layer consists of the material, which is also generally preferred. The compounds described within the scope of the present invention, in particular oxides, nitrides, and carbides, can in principle be stoichiometric, substoichiometric, or superstoichiometric, although the stoichiometric molecular formulas are mentioned for the sake of clarity.

[0029] The electrically conductive layer preferably has a refractive index of 1.7 to 2.3. In one advantageous embodiment, the electrically conductive layer contains at least one transparent, electrically conductive oxide (TCO). Such layers are corrosion-resistant and can be used on exposed surfaces. The electrically conductive layer preferably contains indium tin oxide (ITO), which has proven particularly useful, in particular due to its low specific resistance and low scatter in sheet resistance. Alternatively, the conductive layer can also contain, for example, aluminum-zinc mixed oxide (AZO), indium-zinc mixed oxide (IZO), gallium-doped tin oxide (GZO), fluorine-doped tin oxide (SnO2:F) or antimony-doped tin oxide (SnO2:Sb).

[0030] The thickness of the electrically conductive layer is from 75 nm to 120 nm, particularly preferably from 75 nm to 100 nm, and particularly preferably from 80 nm to 95 nm. This achieves particularly good results in terms of electrical conductivity while simultaneously maintaining sufficient optical transparency. In this layer thickness range, sufficient emissivity-reducing properties are also achieved without simultaneously producing a very strong color tint on the pane.

[0031] In an advantageous embodiment, the layer thickness of the dielectric anti-reflective coating is preferably from 5 nm to 50 nm, preferably from 5 nm to 30 nm, particularly preferably from 5 nm to 20 nm, and most preferably from 10 nm to 15 nm. In this layer thickness range, a particularly low coloration of the pane is achieved. The coloration is particularly low in a layer thickness range from 5 nm to 20 nm, preferably from 10 nm to 15 nm. This finding was unexpected and surprising for the inventors.

[0032] When talking about thin layers, i.e. layers with a thickness of less than 1000 nm, the following applies: if something is "based" on a material, it consists predominantly of this material, in particular essentially of this material alongside any impurities or dopants. Unless otherwise stated, the specification of layer thicknesses refers to the geometric thickness of a layer. If something is "based" on a polymeric material, it consists predominantly of this material, i.e. at least 50%, preferably at least 60%, and in particular at least 70%. It can therefore also contain other materials such as stabilizers or plasticizers.

[0033] In an advantageous embodiment, the layer thickness of the dielectric optical layer is preferably from 30 nm to 120 nm, preferably from 50 to 100 nm, particularly preferably from 55 nm to 75 nm, in particular from 60 nm to 70 nm. The coloration is particularly low in a layer thickness range from 55 nm to 75 nm, preferably 60 nm to 70 nm. This finding was unexpected and surprising for the inventors.

[0034] In a particularly advantageous embodiment, the layer stack comprises further anti-reflective layers and / or optical layers.

[0035] Anti-reflective coatings and optical coatings provide particularly advantageous optical properties for the pane. They reduce the degree of reflection, thereby increasing the pane's transparency and ensuring a neutral color impression. The anti-reflective coatings preferably contain an oxide or fluoride, particularly preferably silicon oxide, aluminum oxide, magnesium fluoride, or calcium fluoride. The silicon oxide may be doped and is preferably doped with aluminum (SiO2:Al), boron (SiO2:B), titanium (SiO2:Ti), or zirconium (SiO2:Zr). Alternatively, the coatings may also contain, for example, aluminum oxide (Al2O3).

[0036] In a particularly advantageous embodiment, the optical layer is the topmost layer of the layer stack. It is thus at the greatest distance from the substrate surface and is the final layer of the layer stack, which is exposed, accessible, and touchable by people. Additional layers, especially those with a higher refractive index than the anti-reflective layer, above the anti-reflective layer would alter the optical properties and could reduce the desired effect.

[0037] It has been shown that the oxygen content of the electrically conductive layer, particularly when it is based on a TCO, has a significant influence on its properties, in particular on transparency, color and conductivity. The production of the pane typically comprises a temperature treatment, for example a thermal tempering process, during which oxygen can diffuse to the conductive layer and oxidize it. The layer stack according to the invention comprises, between the electrically conductive layer and the optical layer, a dielectric blocker layer for regulating oxygen diffusion with a refractive index of at least 1.9 and a layer thickness of 10 nm to 25 nm, preferably 10 nm to 20 nm, more preferably 12 nm to 20 nm, most preferably 12 nm to 18 nm, in particular 15 nm to 18 nm. Particularly good results are achieved when the refractive index of the blocker layer is 1.9 to 2.5.The blocker layer serves to adjust the oxygen supply to an optimal level. It has been found that at lower layer thicknesses of the blocker layer, overoxidation of the layer material can occur during temperature treatment. This overoxidation can reduce the electrical conductivity and emissivity-reducing effect of the layer stack. At the specified layer thickness ranges of the blocker layer, the conductivity and emissivity-reducing effect could be stabilized. This improvement was surprising and unexpected for the inventors. The dielectric blocker layer for regulating oxygen diffusion contains at least one metal, a nitride, or a carbide. The blocker layer can, for example, contain titanium, chromium, nickel, zirconium, hafnium, niobium, tantalum, or tungsten, or a nitride or carbide of tungsten, niobium, tantalum, zirconium, hafnium, chromium, titanium, silicon, or aluminum.In a preferred embodiment, the blocker layer contains silicon nitride (SisN^) 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 development, is doped with aluminum (SisN^Al), with zirconium (SisN^Zr), with titanium (SisN^Ti), or with boron (SisN^B). During a temperature treatment after the application of the layer stack, the silicon nitride can be partially oxidized. A blocker layer deposited as SisN4 then contains Si after the temperature treatment. x N y O z , with the oxygen content typically ranging from 0 atomic% to 35 atomic%.

[0038] The layer stack contains a dielectric barrier layer beneath the electrically conductive layer and the anti-reflective layer to prevent alkali diffusion. The barrier layer reduces or prevents the diffusion of alkali ions from the glass substrate into the layer system. Alkali ions can negatively influence the properties of the coating. Furthermore, the barrier layer, in conjunction with the anti-reflective layer, contributes advantageously to adjusting the color and reflection of the overall layer structure. The refractive index of the barrier layer is preferably at least 1.9. Particularly good results are achieved when the refractive index of the barrier layer is between 1.9 and 2.5.The barrier layer preferably contains an oxide, a nitride or a carbide, preferably of tungsten, chromium, niobium, tantalum, zirconium, hafnium, titanium, silicon or aluminum, for example oxides such as WO 5 , Nb 2 O 5 , Bi 2 O 5 , TiO 2 , Ta 2 O 5 , ZrO 2 , HfO 2 , SnO 2 , or ZnSnO x , or nitrides such as AlN, TiN, TaN, ZrN or NbN. The barrier layer particularly preferably contains silicon nitride (SisN^), with which particularly good results are achieved. The silicon nitride can be doped and, in a preferred development, is doped with aluminum (SisN^Al), with titanium (SisNzrTi), with zirconium (SisN^Zr) or with boron (SisN^B). The layer thickness of the barrier layer is, according to the invention, from 5 nm to 18 nm, particularly preferably from 10 nm to 18 nm, in particular from 12 nm to 18 nm. The barrier layer is preferably the bottommost layer of the layer stack, thus having direct contact with the substrate surface, where it can optimally develop its effect.Layer thicknesses of 5 nm to 18 nm, especially 12 nm to 18 nm, are particularly suitable, as they maintain good deformability of the wafer, for example, during subsequent bending. At the same time, the barrier layer also serves as an adhesion layer for the remaining layers on the substrate, making a layer thickness of greater than 10 nm preferable.

[0039] In an advantageous embodiment, the coating consists exclusively of layers with a refractive index of at least 1.9 or of at most 1.8, preferably at most 1.6. In a particularly preferred embodiment, the layer stack consists only of the described layers and contains no further layers.

[0040] In a preferred embodiment of the invention, the barrier layer has a layer thickness of 5 nm to 18 nm, the anti-reflective layer has a layer thickness of 5 nm to 20 nm, and the optical layer has a layer thickness of 55 nm to 75 nm. This achieves optimal optical properties with regard to reflection and coloration of the layer stack without compromising the stability or transparency of the pane. Particularly preferably, the layer stack consists only of the described layers—i.e., blocking layer, anti-reflective layer, electrically conductive layer, barrier layer, and optical layer—and contains no further layers.

[0041] In a particularly preferred embodiment of the invention, the barrier layer has a thickness of 5 nm to 18 nm, the anti-reflective layer has a thickness of 5 nm to 20 nm, and the optical layer has a thickness of 55 nm to 75 nm. At these thicknesses, only a very low degree of coloration and reflection is visually perceptible compared to conventional panes.

[0042] The inventors have surprisingly discovered that a pane with the electrically conductive layer stack according to the invention, which is adjusted so that it has a local minimum of the reflectance in the range from 360 nm to 440 nm and a local maximum of the reflectance in the range from 310 nm to 360 nm at an angle of incidence of 8°, leads to a more neutral color impression of the pane without the reflectance of the coated pane being significantly increased at the same time.

[0043] In a preferred embodiment of the invention, the reflectance of the substrate surface coated with the layer stack according to the invention is at most 10%, preferably at most 5%, in particular at most 4%. Measured with visible light radiation impinging on the coated surface of the substrate at an angle of incidence of 8°.

[0044] The local minimum of the reflectance is preferably in the range from 315 nm to 355 nm, particularly preferably from 320 nm to 350 nm. The local maximum of the reflectance is preferably in the range from 415 nm to 450 nm. These local extreme values ​​are to be understood as minimum requirements and are not intended to exclude the possibility that they are global extreme values. While in the case of the maximum of the reflectance, at least outside the visible range, spectral ranges will exist that have a higher reflectance, it is conceivable that the said local minimum of the reflectance is the global minimum in the mathematical sense.

[0045] The term "reflectance" is used in the sense of the standard DIN EN 410 - 2011-04. The reflectance always refers to the layer-side reflectance, which is measured when the coated surface of the disc faces the light source and the detector. Refractive indices are generally specified within the scope of the present invention based on a wavelength of 550 nm. Methods for determining refractive indices are known to those skilled in the art. The refractive indices specified within the scope of the invention can be determined, for example, by means of ellipsometry, whereby commercially available ellipsometers can be used. Unless otherwise stated, the specification of layer thicknesses or thicknesses refers to the geometric thickness of a layer.

[0046] The reflectance is measured at an angle of incidence of 60° or 8° (unless otherwise specified) to the interior surface normal (the surface of the substrate coated with the layer stack), which roughly corresponds to the natural viewing angle of the windshield in a vehicle. The spectral range from 380 nm to 680 nm was used to characterize the reflection properties because the viewer's visual impression is primarily determined by this spectral range.

[0047] The reflectance describes the proportion of the total incident radiation that is reflected. It is expressed as a percentage (relative to 100% incident radiation) or as a unitless number from 0 to 1 (normalized to the incident radiation). Plotted as a function of wavelength, it forms the reflection spectrum. The information on the reflectance or reflection spectrum refers to a reflection measurement with a light source that radiates uniformly in the spectral range under consideration with a normalized radiation intensity of 100%.

[0048] The occurrence of local extremes of the reflectance is crucial for the reduced visibility of fingerprints or surface contamination. These properties can fundamentally be realized through a variety of layer structure designs of the coating, and the invention is not intended to be limited to a specific layer structure. The distribution of extreme values ​​is fundamentally determined by the selection of the layer sequence, the materials of the individual layers, and the respective layer thicknesses, whereby it can be influenced by a heat treatment taking place after coating. However, certain designs have proven particularly advantageous with regard to optimized material use and other optical properties, which are presented below.

[0049] The interior emissivity of the pane according to the invention is preferably less than or equal to 45%, more preferably less than or equal to 35%, most preferably less than or equal to 25%, and in particular less than or equal to 20%. Interior emissivity refers to the measure indicating how much thermal radiation the pane emits into an interior, for example, a building or vehicle, in its installed position compared to an ideal heat radiator (a black body). For the purposes of the invention, emissivity is understood to mean the normal emissivity at 283 K according to the EN 12898 standard.

[0050] The sheet resistance of the layer stack according to the invention is preferably from 10 ohms / square to 100 ohms / square, particularly preferably from 15 ohms / square to 35 ohms / square.

[0051] The substrate is made of an electrically insulating, particularly rigid material, preferably glass or plastic. In a preferred embodiment, the substrate contains soda-lime glass, but can in principle also contain other types of glass, for example borosilicate glass or quartz glass. In a further preferred embodiment, the substrate contains polycarbonate (PC) or polymethyl methacrylate (PMMA). The substrate can be largely transparent or tinted or colored. The substrate preferably has a thickness of 0.1 mm to 20 mm, typically 2 mm to 5 mm. The substrate can be flat or curved. In a particularly advantageous embodiment, the substrate is a thermally toughened glass pane.

[0052] In a preferred embodiment of the invention, the pane has an a* value of the L*a*b* color space of at most +10, preferably at most +5, in particular at most +3, at a viewing angle α of at least 60° to the coated surface. The layers of the layer stack are therefore arranged such that the a* value of the L*a*b* color space is at most +10, preferably at most +5, in particular at most +3, at a viewing angle α of at least 60° to the coated surface. It has been found that a high a* content leads to a dominant coloration of the pane. The visually perceived coloration depends on the viewing angle α and, in the case of panes of this type, is particularly pronounced for viewing angles above 60°.

[0053] The viewing angle α is measured from a normal to the surface plane of the disc, i.e., an axis perpendicular to the surface plane of the disc. A viewing angle α of 0° represents a vertical view of one of the outer surfaces of the disc. A viewing angle α of 90° represents a horizontal view along one of the outer surfaces of the disc.

[0054] The symbols a* and b* are values ​​of the L*a*b* color space, a color model that describes all perceivable colors. L* indicates the brightness value and can have values ​​between 0 and 100, a* indicates the chromaticity and color intensity between green and red, while b* indicates the chromaticity and color intensity between blue and yellow. The more negative or positive the values ​​of b* and a* are, the more intense the hue. Values ​​close to 0 for a* and b* indicate a rather achromatic, i.e., neutral, hue.

[0055] Common measurement methods for determining a*, b*, and L* values ​​of the L*a*b* color space (CIELAB) are generally known to those skilled in the art. Common measuring instruments for determining these values ​​are commercially available, such as the Minolta CM508d spectrometer from Konica Minolta Sensing Europe BV or the Tec5 spectrometer from tec5 AG. To determine the a*, b*, and L* values ​​of the L*a*b* color space, the measurement conditions must first be established. For example, the type of light (D50, D65, A or others, see DIN 5033-7:2014-10), the standard observer (2° or 10° see DIN 5033-7:2014-10), the measuring geometry (directional or diffuse illumination see DIN 5033-7:2014-10), the measuring mode (reflection in plan view or transmission in transmitted view), the measuring points of the sample and the number of measurements must be specified.The term "standard observer" refers to the average visual acuity of the color-normally sighted population at different field sizes (DIN 5033-7:2014-10). To enable a uniform assessment, the International Commission on Illumination (CIE) defined spectral weighting functions. These weighting functions describe how a standard observer perceives color. The assessment is based on experimentally determined sensitivity curves of the long-wavelength, medium-wavelength, and short-wavelength cones of the human eye (see also DIN 5033-1:2017-10).

[0056] For example, to measure the a* value, the coated disc can be illuminated at a predetermined angle. Illuminated at a "predetermined angle," however, does not necessarily mean that the light hitting the coated disc only has the predetermined angle of incidence. For example, the coated disc can be illuminated with diffuse light, with the light hitting the coated disc at several different angles of incidence, preferably at least at an angle of 60° to 90°. A detector of a measuring device records the light reflected from the sample. The spectral intensity of the reflected light is obtained over a wavelength range from 360 nm to 830 nm. The resulting spectrum is then integrated only in the ranges that coincide with one of the sensitivity curves of the long-wave, medium-wave, and short-wave cones.In this way, the integrals for the long-wave, medium-wave, and short-wave light components are formed, which are then mathematically transformed into the a*, b*, and L* values ​​of the L*a*b* color space according to DIN 6174:2007-10. It is understood that to determine the a*, b*, and L* values, the detector captures the reflected light at a viewing angle a to the disc. A linear polarizing filter can be arranged between the detector and the sample, i.e., in the beam path of the reflected light. The angle at which the sample is illuminated can range from 0° to 90°, preferably from 0° to 80°, to the surface of the coated disc (measured from a normal to the surface plane of the disc).

[0057] The a* value is preferably measured for a standard observer of 10°. Standard illuminant D65 (average daylight at approximately 6500 Kelvin) is preferably used. The measurement mode is preferably reflection in plan view, and the coated disc is illuminated with diffuse light. The detector is preferably equipped with a linear polarizing filter.

[0058] The substrate can be transparent or semi-transparent, for example, tinted. "Transparent" in the context of the invention means a light transmission (according to ISO 9050:2003) of at least 50%, preferably at least 60%, and particularly preferably at least 70%. Semi-transparent (according to ISO 9050:2003) in the context of the invention means a light transmission of at most 50%, preferably at most 30%, and particularly preferably at most 10%.

[0059] The invention further extends to a composite pane comprising the coated pane according to the invention, a second pane and a thermoplastic intermediate layer arranged between the coated pane and the second pane.

[0060] The second pane preferably comprises a substrate or consists essentially of a substrate, which is preferably constructed like the substrate of the coated pane.

[0061] The thermoplastic intermediate layer is preferably formed as at least one thermoplastic composite film and is based on ethylene vinyl acetate (EVA), polyvinyl butyral (PVB) or polyurethane (PU) or mixtures or copolymers or derivatives thereof, particularly preferably based on polyvinyl butyral (PVB) and additionally additives known to the person skilled in the art, such as plasticizers. The thermoplastic film preferably contains at least one plasticizer. The invention also encompasses a method for producing a coated pane with an electrically conductive layer stack, wherein

[0062] (A) the substrate is provided and

[0063] (B) the barrier layer, the anti-reflective layer, the electrically conductive layer, the blocking layer and the optical layer are applied in this order as a layer stack on the surface, preferably by means of magnetron sputtering.

[0064] After the layer stack has been applied, the pane is preferably subjected to a heat treatment, which particularly improves the crystallinity of the optical layer, especially if the optical layer is a TCO layer. The heat treatment is preferably carried out at at least 300°C, particularly preferably at at least 500°C. The heat treatment, in particular, reduces the sheet resistance of the coating. Furthermore, the optical properties of the pane or substrate are significantly improved, in particular by increasing the transmission.

[0065] The heat treatment can be carried out in various ways, for example, by heating the wafer or substrate using an oven or a radiant heater. Alternatively, the heat treatment can also be carried out by irradiation with light, for example, using a lamp or laser as the light source.

[0066] In an advantageous embodiment, the heat treatment of a glass substrate takes place as part of a thermal tempering process. The heated substrate is exposed to an air stream, which rapidly cools it. Compressive stresses develop on the pane surface and tensile stresses in the pane core. This characteristic stress distribution increases the fracture strength of the glass panes. Tempering can also be preceded by a bending process.

[0067] The individual layers of the layer stack are deposited using conventional methods, preferably by magnetic field-assisted cathode sputtering (magnetron sputtering). This is particularly advantageous with regard to a simple, fast, cost-effective, and uniform coating of the substrate. Cathode sputtering takes place in a protective gas atmosphere, for example, argon, or in a reactive gas atmosphere, for example, by adding oxygen or nitrogen. However, the layers can also be applied using other methods known to those skilled in the art, for example, by vapor deposition or chemical vapor deposition (CVD), by atomic layer deposition (ALD), by plasma-enhanced chemical vapor deposition (PECVD), or by wet-chemical processes.

[0068] To select suitable materials and layer thicknesses to achieve the appropriate reflection spectrum, the specialist can, for example, use standard simulations.

[0069] The invention further encompasses the use of a pane according to the invention in buildings, in electrical or electronic devices, or in means of transport for land, air, or water traffic. The pane is preferably used as a window pane, for example, as a building window pane or as a roof pane, side window, rear window, or windshield of a vehicle, in particular a motor vehicle.

[0070] The invention is explained in more detail below with reference to drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings do not limit the invention in any way.

[0071] They show:

[0072] Fig. 1 shows a cross section through an embodiment of the pane according to the invention with electrically conductive layer stacks,

[0073] Fig. 2 shows a cross section through an embodiment of a composite pane with the pane according to the invention,

[0074] Fig. 3-5 diagrams of the reflectance R as a function of the wavelength for 4 examples according to the invention and a comparative example and

[0075] Fig. 6 Diagram with a* and b* as a function of the viewing angle a for example 1 and the comparison example.

[0076] Fig. 1 shows a cross-section through an embodiment of the pane 100 according to the invention, comprising the substrate 1 and the electrically conductive layer stack 2. The substrate 1 is, for example, a glass pane made of tinted soda-lime glass and has a thickness of 2.1 mm. The layer stack 2 is a heat-radiation-reflecting coating (low-E coating). The pane 100 is intended, for example, as the roof pane of a motor vehicle. Roof panes are typically designed as laminated glass panes, with the substrate 1 being bonded to an outer pane (not shown) via its surface facing away from the coating 2 by means of a thermoplastic film (see Figure 2).

[0077] The optical properties of the layer stack 2 are optimized such that, for a vehicle occupant, the layer stack reflects less visible light without resulting in intense coloration of the pane 100 compared to conventional panes. This is achieved according to the invention by a sequence of thin layers, which, starting from the substrate 1, consists of the following individual layers: a barrier layer 3 against alkali diffusion with a refractive index of at least 1.9, an anti-reflective layer 4 with a refractive index of at most 1.6, an electrically conductive layer 5, a blocker layer 6 for regulating oxygen diffusion with a refractive index of at least 1.9, and an optical layer 7 with a refractive index of at most 1.6.

[0078] An example of the layer sequence, including materials and layer thicknesses, is summarized in Table 1. The individual layers of the layer stack 2 were deposited, for example, by magnetic field-assisted cathode ray sputtering. The low light reflection and the reduced color impression compared to conventional panes can be achieved in particular by the precisely adjusted layer thickness of the electrically conductive layer 5 and the blocking layer 6.

[0079] Table 1 with Example 1 Fig. 2 shows a cross-sectional view of a composite pane with the pane 100 according to the invention from Fig. 1 as the inner pane and a second pane 101 as the outer pane. The composite pane is, for example, a roof pane installed in a vehicle. The electrically conductive layer stack 2 is applied to an interior-side surface IV of the substrate 1 facing the vehicle interior. The substrate has an exterior surface III facing the thermoplastic intermediate layer 102, which likewise faces the exterior environment. The second substrate 8, which is also the second pane 101, has an interior-side surface II facing the vehicle interior and an exterior surface I facing the exterior environment. The second pane 101 is, for example, 1.5 mm thick. The thermoplastic intermediate layer 102 consists, for example, of polyvinyl butyral with a plasticizer content of less than 10 percent by weight.The layer thickness of the thermoplastic intermediate layer is, for example, 0.5 mm.

[0080] Fig. 3-5 show diagrams of the reflectance R for four examples according to the invention and one comparative example. The reflectance R values ​​shown were determined by simulations using the CODE software. Fig. 3 shows Example 1 and the comparative example. Fig. 4 shows Examples 2 and 3 and the comparative example. Fig. 5 shows Examples 4 and the comparative example. The materials and layer thicknesses of layer stack 2 of Example 1 are summarized in Table 1. The materials and layer thicknesses of layer stack 2 of Examples 2 to 4 are summarized in Table 2, and those of the comparative example are summarized in Table 3.In Examples 1-4, the pane consisted of a substrate 1 made of tinted soda-lime glass with a light transmission TL of approximately 25% and the layer stack 2, which, starting from substrate 1, was constructed from a barrier layer 3, an anti-reflective layer 4, an electrically conductive layer 5, a blocking layer 6, and an optical layer 7. The layers were made of the same materials, with the layers of layer stack 2 in Examples 1-4 differing in their layer thicknesses. All panes had been subjected to a heat treatment as part of a glass bending process at approximately 650°C. Table 2.

[0081] Table 3

[0082] The comparative example shows a pane with a conventional layer stack. The comparative example differs fundamentally from the inventive examples 1 to 4 in the significantly lower layer thickness of the electrically conductive layer 5, optical layer 7, and blocking layer 6. At the same time, the layer thickness of the anti-reflective layer 4 and the barrier layer 3 is significantly higher than for the inventive examples. The reflectance R for the comparative example is in most cases in the range 350 nm to 550 nm, which is significantly higher than for the inventive examples. Light reflections in this wavelength range in particular can be irritating for viewers, for example the driver, which is why lower light reflection in this range represents a major advantage. The reflectance R shown in Figures 3 to 5 was simulated for an angle of incidence of light onto the layer stack 2 of 8°.The differences in reflectance in the wavelength range 350 nm to 550 nm between the inventive examples and the comparative example are also measurable for angles of incidence of 60°. In contrast to inventive examples 1-4, the local extremes of the reflectance R in the comparative example were not located at 310 to 360 nm (maximum) and 360 nm to 440 nm (minimum). The occurrence of the local extremes is summarized in Table 4. The values ​​of the reflectance RL shown were determined by simulations using the CODE software.

[0083] Table 4

[0084] The lower reflection peaks in the higher wavelength range compared to conventional glass reduce optical irritation for viewers. Reflections in the lower wavelength range are generally perceived as more neutral color reflections.

[0085] Figure 6 shows the a* and b* values ​​(LAB color space) for Example 1 and the Comparative Example. The a* and b* values ​​shown are plotted as a function of the viewing angle (60° to 85°) on surface IV of substrate 1 coated with layer stack 2. It can be seen that the a* values, which are particularly responsible for a dominant coloration of the pane 100, are significantly lower in Example 1 according to the invention than for the Comparative Example. The b* values ​​are similarly high on average across the viewing angles for the Comparative Example and Example 1 according to the invention. The pane 100 coated with the layer stack 2 according to the invention from Example 1 therefore makes a more color-neutral impression overall than a pane coated in the same way. List of reference symbols:

[0086] 1 substrate

[0087] 2 layer stacks

[0088] 3 Barrier layer

[0089] 4 Anti-reflective coating

[0090] 5 electrically conductive layer

[0091] 6 Blocker layer

[0092] 7 optical layer

[0093] 8 second substrate

[0094] 100 slices

[0095] 101 second disc

[0096] 102 thermoplastic intermediate layer

[0097] I outer surface of the second substrate 8

[0098] II interior surface of the second substrate 8

[0099] III outer surface of the substrate 1

[0100] IV Interior surface of the substrate 1

[0101] RL reflectance (according to DIN EN410)

Claims

Coated pane (100), comprising a substrate (1) and an electrically conductive layer stack (2) on a surface (IV) of the substrate (1), which, starting from the substrate (1), comprises at least - a dielectric barrier layer (3) against ion diffusion with a refractive index of at least 1.9 and a layer thickness of 5 nm to 18 nm, - a dielectric anti-reflection layer (4) with a refractive index of not more than 1.6, - an electrically conductive layer (5) with a layer thickness of 75 nm to 120 nm, - a dielectric blocking layer (6) for regulating oxygen diffusion with a refractive index of at least 1.9 and a layer thickness of 10 nm to 25 nm and - a dielectric optical layer (7) with a refractive index of at most 1.

6. The disc (100) according to claim 1, wherein the electrically conductive layer (5) contains a transparent conductive oxide (TCO), preferably indium tin oxide (ITO). The disc (100) according to claim 1 or 2, wherein the electrically conductive layer (5) has a layer thickness of 80 to 95 nm. The disc (100) according to any one of claims 1 to 3, wherein the anti-reflection layer (4) and / or the optical layer (7) contains at least one oxide, preferably silicon oxide, particularly preferably aluminum-doped, zirconium-doped, titanium-doped or boron-doped silicon oxide. The disc (100) according to any one of claims 1 to 4, wherein the optical layer (7) has a layer thickness of 55 nm to 75 nm, preferably 60 nm to 70 nm. Pane (100) according to one of claims 1 to 5, wherein the anti-reflection layer (4) has a layer thickness of 5 nm to 20 nm, preferably of 10 nm to 15 nm. The disc (100) according to one of claims 1 to 6, wherein the barrier layer (3) and / or the blocker layer (6) contains a metal, a nitride, or a carbide, preferably silicon nitride or silicon carbide, in particular silicon nitride. The disc (100) according to one of claims 1 to 7, wherein the barrier layer (3) has a layer thickness of 12 nm to 18 nm. The disc (100) according to one of claims 1 to 8, wherein the blocker layer (6) has a layer thickness of 12 nm to 25 nm. The disc (100) according to one of claims 1 to 9, which has a local minimum of the reflectance (R ) in the range from 360 nm to 440 nm and a local maximum of the reflectance (R ) in the range from 310 nm to 360 nm. Pane (100) according to one of claims 1 to 10, which has an emissivity over the coated surface (IV) of at most 25%, preferably at most 20%, compared to an ideal heat radiator.Pane (100) according to one of claims 1 to 11, wherein, at a viewing angle α of at least 60° onto the coated surface (I), the pane (100) has an a* value of the L*a*b* color space of at most +10, preferably at most +5, particularly preferably at most +3. A composite pane comprising. - a coated disc (100) according to one of claims 1 to 12, - a second disc (101) and - a thermoplastic intermediate layer (102) arranged between the coated pane (100) and the second pane (101). A method for producing a coated pane (100) according to any one of claims 1 to 12, wherein (A) the substrate (1) is provided and (B) the barrier layer (3), the anti-reflective layer (4), the electrically conductive layer (5), the blocking layer (6) and the optical layer (7) in this order as a layer stack (2) on the surface (I), preferably by means of Magnetron sputtering. Use of a coated pane (100) according to one of claims 1 to 12 in buildings, in electrical or electronic devices, or in means of transport for land, air, or water traffic, in particular as a window pane, for example as a building window pane or roof pane, side window, rear window, or windshield of a vehicle.

Images