EP4605351A1 - Disc coated with an electrically conductive layer stack - Google Patents

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

Disc coated with electrically conductive layer stack

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.

Glass panes with transparent, electrically conductive coatings are well known. The glass panes can thus be given a function without significantly impairing the view through the pane. Such coatings are used, for example, as heatable coatings or coatings that reflect heat radiation on window panes for vehicles or buildings.

The interior of a vehicle or a building can heat up considerably in summer when the ambient temperature is high and there is intense direct sunlight. If, however, the outside temperature is lower than the temperature inside, 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 a high degree to prevent cooling through the window panes.

Coatings that reflect heat radiation (so-called low-E coatings) reflect a significant portion of solar radiation, particularly in the infrared range, which leads to reduced heating of the interior in summer. The coating also reduces the emission of long-wave heat radiation from a heated window into the interior. It also reduces the radiation of heat from the interior into the outside environment when the outside temperature is low in winter.

To be effective, the heat radiation-reflecting coating must be placed on 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 rules out the use of corrosion-prone coatings, for example those based on silver. Coatings based on transparent conductive oxides (TCO), for example Indium tin oxide (ITO). 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 with reflective properties in relation to thermal radiation, wherein fingerprints on the electrically conductive layer are less visible due to a special layer structure.

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.

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

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.

Windows with a low-E coating should 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 usually applied to windows in the automotive sector. If the entire surface of a window has been pre-coated with a low-E coating, there may be problems with the adhesion of the screen print to the window. This may 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.

Another common problem that occurs with low-E coatings in connection with windows, especially tinted windows, is increased light reflection and a coloring of the window due to the coating, which depends on the viewing angle. High reflection and a coloring of the window can have a distracting or aesthetically disturbing effect on the viewer, which can also pose a safety risk, especially when the window is used as a vehicle window. In generic windows, the color neutrality and light reflection depend on the viewing angle. reciprocally. This means that the coated pane has a lower light reflection but a stronger color and vice versa.

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.

The object of the present invention is achieved by a coated pane according to claim 1. Preferred embodiments emerge from the subclaims.

The pane according to the invention comprises a substrate and an electrically conductive layer stack on a surface of the substrate. The layer stack has, starting from the substrate, in the following order:

- 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,

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

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

- 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

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

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 a high color. However, users may find high reflection and/or color irritating and disturbing. It can also pose a safety risk if, for example, light is reflected too strongly on a window in a car or traffic signs outside the car are perceived incorrectly (for example, a red sign takes on a greenish-reddish color when viewed through the window). The tint of the window depends on the viewing angle. In particular, flat viewing angles of 60° to 85° to the surface of the window lead to a strong color when viewed through or reflected. These flat viewing angles occur particularly in Windscreens (flat installation angle) and roof windows (flat viewing angle for passengers sitting in the back) in vehicles. The inventors found that the dominant color component, which is largely responsible for the visually highly perceptible coloring in generically coated windows, is due to high positive a* values of the LAB color space. High positive a* values have an effect on visual perception by giving the window a red tint.

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 from radiating into the interior (IR components of solar radiation and in particular the thermal radiation of the window itself) and also to prevent heat from radiating out of the interior. In principle, however, the layer stack can also fulfill other functions, for example as a heatable coating if it is electrically contacted so that it is heated as a result of an electric current flow.

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. In the sense of the invention, the interior-side surface is understood to mean the surface that is intended to face the interior when the pane is installed. This is particularly advantageous with regard to thermal comfort in the interior. The layer stack according to the invention can particularly effectively reflect the heat radiation emitted by the entire pane in the direction of the interior at high outside temperatures and in the presence of sunlight, at least in part. At low outside temperatures, the layer stack can effectively reflect the heat radiation emitted from the interior and thus reduce the effect of the cold pane as a heat sink. Usually, the surfaces of a glazing are numbered from the outside to the inside, so that the interior surface of single glazing is referred to as “side 2” and of double glazing (for example laminated glass or insulating glass) as “side 4”. Alternatively, the layer stack can also be placed on the outside surface of the substrate. This can be particularly useful in the architectural field, for example as an anti-condensation coating on a window pane.

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

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 other layers and can be specifically adjusted by their design. In this context, so-called anti-reflective layers and optical layers, which have a lower refractive index than the electrically conductive layer and are arranged above and below it, have a particular influence. The anti-reflective layers, which interact with optical layers, can increase the transmission through the pane and reduce the reflectivity, in particular 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).

The layer stack according to the invention is transparent, so it does not noticeably restrict visibility 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.

If a first layer is arranged above a second layer, this means in the sense 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 in the sense 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 arranged 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.

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 data transmission, for example. The coated portion of the substrate surface is preferably at least 80%, in particular at least 90%.

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 preferred in principle. The compounds described in the context of the present invention, in particular oxides, nitrides and carbides, can in principle be stoichiometric, substoichiometric or superstoichiometric, even if the stoichiometric molecular formulas are mentioned for the sake of better understanding.

The electrically conductive layer preferably has a refractive index of 1.7 to 2.3. In an 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 a low specific resistance and a low scatter in terms of the surface 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 (SnÜ2:F) or antimony-doped tin oxide (SnO2:Sb).

The thickness of the electrically conductive layer is from 75 nm to 120 nm, particularly preferably from 75 nm to 100 nm, particularly preferably from 80 nm to 95 nm. This achieves particularly good results in terms of electrical conductivity at at the same time, 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.

In an advantageous embodiment, the layer thickness of the dielectric anti-reflective layer is preferably from 5 nm to 50 nm, preferably from 5 nm to 30 nm, particularly preferably from 5 nm to 20 nm, very particularly 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 10 nm to 15 nm. This finding was unexpected and surprising for the inventors.

When we talk 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 along with any impurities or dopants. The specification of layer thicknesses or thicknesses refers, unless otherwise stated, 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.

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 coloring 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.

In a particularly advantageous embodiment, the layer stack has further anti-reflective layers and/or optical layers.

Anti-reflective coatings and optical coatings provide particularly advantageous optical properties for the pane. They reduce the degree of reflection and thereby increase the transparency of the pane and ensure 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 can contain dopants and is preferably doped with aluminum (SiO2:Al), with boron (SiO2:B), with titanium (SiO2:Ti) or with zirconium (SiO2:Zr). Alternatively, the layers can also contain aluminum oxide (Al2O3), for example.

In a particularly advantageous embodiment, the optical layer is the topmost layer of the layer stack. It is therefore at the greatest distance from the substrate surface and is the final layer of the layer stack that is exposed, accessible and touchable by people. Additional layers, in particular with a higher refractive index than the anti-reflective layer, above the anti-reflective layer would change the optical properties and could reduce the desired effect.

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, coloring and conductivity. The production of the pane typically includes a temperature treatment, for example a thermal tempering process, whereby oxygen can diffuse to the conductive layer and oxidize it. The layer stack according to the invention comprises a dielectric blocker layer between the electrically conductive layer and the optical 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, particularly preferably 12 nm to 20 nm, very particularly 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 with lower layer thicknesses of the blocker layer, overoxidation of the layer material can occur during the temperature treatment. Overoxidation can reduce the electrical conductivity and emissivity-reducing effect of the layer stack. With the layer thickness ranges mentioned for the blocker layer, the conductivity and emissivity-reducing effect could be stabilized. This improvement was surprising and unexpected for the inventors. The dielectric blocking layer for regulating oxygen diffusion contains at least one metal, a nitride or a carbide. The blocking layer can contain, for example, 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 have doping 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 _x N _y O _z after the temperature treatment, with the oxygen content typically being from 0 atomic % to 35 atomic %.

The layer stack contains a dielectric barrier layer against alkali diffusion beneath the electrically conductive layer and beneath the anti-reflective layer. The barrier layer reduces or prevents the diffusion of alkali ions from the glass substrate into the layer system. Alkali ions can have a negative effect on the properties of the coating. Furthermore, the barrier layer, in conjunction with the anti-reflective layer, makes a beneficial contribution 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 s, Nb 2 O s, Bi 2 O s, 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^, which achieves particularly good results. The silicon nitride can have doping 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 bottom layer of the layer stack, so it has direct contact with the substrate surface, where it can optimally develop its effect. Layer thicknesses of 5 nm to 18 nm, in particular from 12 nm to 18 nm are suitable. This is particularly useful because it allows the pane to retain its good deformability, for example when it is subsequently bent. At the same time, the barrier layer also serves as an adhesive layer for the other layers on the substrate, which is why a layer thickness of more than 10 nm is preferred.

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 layers described and contains no further layers.

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 in terms of reflection and coloring of the layer stack without compromising the stability or transparency of the pane. The layer stack particularly preferably consists only of the layers described, i.e. blocking layer, anti-reflective layer, electrically conductive layer, barrier layer and optical layer, and does not contain any further layers.

In a particularly 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. With these layer thicknesses, only a very low coloration and degree of reflection is visually perceptible compared to conventional panes.

The inventors have surprisingly recognized 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.

In a preferred embodiment of the invention, the reflectance of the surface of the substrate 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 incident on the coated surface of the substrate at an angle of incidence of 8°.

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. The said local extreme values are to be understood as a minimum requirement and should not exclude the case that these 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.

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

The reflectance is measured at an angle of incidence of 60° or 8° (unless otherwise stated) to the interior surface normal (surface of the substrate coated with the layer stack), which corresponds approximately to the natural viewing angle on the window in a vehicle. The spectral range from 380 nm to 680 nm was used to characterize the reflection properties because the optical impression of a viewer is primarily shaped by this spectral range.

The reflection factor describes the proportion of the total incident radiation that is reflected. It is given in % (based on 100% incident radiation) or as a unitless number from 0 to 1 (normalized to the incident radiation). Plotted as a function of the wavelength, it forms the reflection spectrum. The information on the degree of reflection or the reflection spectrum refers to a reflection measurement with a light source that radiates evenly in the spectral range under consideration with a normalized radiation intensity of 100%.

The occurrence of local extremes of the degree of reflection is crucial for the reduced visibility of fingerprints or surface contamination. These properties can in principle be achieved through a variety of designs of the layer structure of the coating, and the invention is not intended to be limited to a specific layer structure. In principle, the extreme value distribution is 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 temperature treatment that takes place after coating. However, certain designs have also proven to be particularly advantageous with regard to optimized material use and other optical properties, which are presented below.

The interior emissivity of the pane according to the invention is preferably less than or equal to 45%, particularly preferably less than or equal to 35%, very particularly preferably less than or equal to 25%, in particular less than or equal to 20%. Interior emissivity refers to the measure that indicates how much heat radiation the pane emits in the installed position into an interior, for example a building or a vehicle, compared to an ideal heat radiator (a black body). In the sense of the invention, emissivity is understood to mean the normal emissivity at 283 K according to the EN 12898 standard.

The surface 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.

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. The substrate contains in a further preferred embodiment, polycarbonate (PC) or polymethyl methacrylate (PMMA). The substrate can be largely transparent or also 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 tempered glass pane.

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 a of at least 60° on 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 a of at least 60° on the coated surface. It has been found that a high a* proportion leads to a dominant coloring of the pane. The visually perceived coloring depends on the viewing angle a and, in the case of panes of this type, is particularly clearly pronounced for viewing angles above 60°.

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

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

Common measurement methods for determining a*, b* and L* values of the L*a*b* color space (CIELAB) are generally known to the expert. Common measuring instruments for determining are commercially available and include 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 defined. 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 measurement geometry (directed or diffuse illumination see DIN 5033-7:2014-10), the measurement mode (reflection in front view or transmission in back view), the measurement points of the sample and the number of measurements must be defined. The term "normal observer" refers to the average visual acuity of the color-normally sighted population at different field sizes (DIN 5033-7:2014-10). In order to enable a uniform assessment, the International Commission on Illumination (CIE) defined spectral evaluation functions. The evaluation functions describe how a normal observer perceives color. The evaluation is based on experimentally determined sensitivity curves of the long-wave, medium-wave and short-wave cones of the human eye (see also DIN 5033-1:2017-10).

For example, to measure the a* value, the coated disk can be illuminated at a predetermined angle. Illuminated at a "predetermined angle", however, does not necessarily mean that the light hitting the coated disk only has an angle of incidence of the predetermined angle. For example, the coated disk can be illuminated with diffuse light, with the light hitting the coated disk at a number of different angles of incidence, preferably at least at an angle of 60° to 90°. A detector in 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 spectrum obtained is then only integrated in the areas 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 in accordance with DIN 6174:2007-10. It is understood that to determine the a*, b* and L* values, the detector records the reflected light at the 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 be from 0° to 90°, preferably from 0° to 80° to the surface of the coated pane (measured from a normal to the surface plane of the pane).

Preferably, the a* value is measured for the standard observer of 10°. The standard light D65 (average daylight with approx. 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.

The substrate can be transparent or semi-transparent, for example tinted. "Transparent" in the sense 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 sense of the invention means a light transmission of at most 50%, preferably at most 30% and particularly preferably at most 10%.

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.

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

The thermoplastic intermediate layer is preferably designed 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 includes a method for producing a coated pane with an electrically conductive layer stack, wherein

(A) the substrate is provided and

(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.

After the layer stack has been applied, the pane is preferably subjected to a temperature treatment which improves the crystallinity of the optical layer, particularly if the optical layer is a TCO layer. The temperature treatment is preferably carried out at at least 300°C, particularly preferably at at least 500°C. The temperature treatment reduces the surface resistance of the coating in particular. In addition, the optical properties of the pane or the substrate are significantly improved, in particular the transmission is increased.

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

In an advantageous embodiment, the temperature treatment in the case of a glass substrate takes place as part of a thermal tempering process. The heated substrate is exposed to an air stream, which causes it to cool quickly. Compressive stresses form on the surface of the pane and tensile stresses in the pane core. The characteristic stress distribution increases the breaking strength of the glass panes. Tempering can also be preceded by a bending process.

The individual layers of the layer stack are deposited using methods known per se, 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. The 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. The layers can also be deposited using other methods that are The layers can be applied using 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 vapor deposition (PECVD) or by wet-chemical methods.

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

The invention also includes the use of a pane according to the invention in buildings, in electrical or electronic devices or in means of transport for traffic on land, in the air or on water. 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.

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

Show it:

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

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

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

Fig. 6 Diagram with a* and b* depending on the viewing angle a for example 1 and the comparison example.

Fig. 1 shows a cross section through an embodiment of the pane 100 according to the invention with 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, for example, designed as Roof pane of a motor vehicle. Roof panes are typically designed as laminated glass panes, with the substrate 1 being connected to an outer pane (not shown) via its surface facing away from the coating 2 by means of a thermoplastic film (see Figure 2).

The optical properties of the layer stack 2 are optimized in such a way that the layer stack reflects less visible light for a vehicle occupant without causing an intense coloration of the pane 100 in comparison 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 blocking 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.

An example of the layer sequence with 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 lower 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 blocker layer 6.

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 that is installed in a vehicle. The electrically conductive layer stack 2 is applied to an interior surface IV of the substrate 1 facing the vehicle interior. The substrate has an exterior surface III facing the thermoplastic intermediate layer 102, which also faces the external environment. The second substrate 8, which is also the second pane 101, has an interior surface II facing the vehicle interior and an exterior surface I facing the external 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.

Fig. 3-5 show diagrams of the reflectance R for four examples according to the invention and a comparative example. The values of the reflectance R 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 the layer stack 2 of example 1 are summarized in table 1. The materials and layer thicknesses of the layer stack 2 of examples 2 to 4 are summarized in Table 2, those of the comparative example 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 about 25% and the layer stack 2, which was built up from substrate 1 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, whereby the layers of the layer stack 2 of examples 1-4 differ in their layer thicknesses. All panes had been subjected to a temperature treatment as part of a glass bending process at about 650°C. Table 2

Table 3

The comparative example shows a pane with a conventional layer stack. The comparative example differs fundamentally from the inventive examples 1 to 4 due to the significantly lower layer thickness of the electrically conductive layer 5, optical layer 7 and block 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. In most cases, the reflectance R for the comparative example is 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 observers, for example the driver, which is why lower light reflection in this range is a great advantage. The reflectance R shown in Figures 3 to 5 was simulated for an angle of incidence of light on the layer stack 2 of 8°. The differences in the reflectance in the wavelength range 350 nm to 550 nm of the inventive examples compared to the comparative example can also be measured for angles of incidence of 60°. In contrast to the 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.

Table 4

The lower reflection maxima in the higher wavelength range compared to conventional panes reduces optical irritation for viewers. Reflections in the lower wavelength range are generally perceived as more neutrally colored reflections.

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

1 substrate

2 layer stack

3 Barrier layer

4 Anti-reflective coating

5 electrically conductive layer

6 Blocker layer

7 optical layer

8 second substrate

100 slice

101 second disc

102 thermoplastic intermediate layer

I outer surface of the second substrate 8

II interior surface of the second substrate 8

III outer surface of the substrate 1

IV Interior surface of the substrate 1

RL Reflectance (according to DIN EN410)

Claims

Patent 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), has 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 - comprises a dielectric optical layer (7) with a refractive index of at most 1.6. Disc (100) according to claim 1, wherein the electrically conductive layer (5) contains a transparent conductive oxide (TCO), preferably indium tin oxide (ITO). Disc (100) according to claim 1 or 2, wherein the electrically conductive layer (5) has a layer thickness of 80 to 95 nm. Disc (100) according to one of claims 1 to 3, wherein the anti-reflective 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. Disc (100) according to 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-reflective layer (4) has a layer thickness of 5 nm to 20 nm, preferably 10 nm to 15 nm. 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. 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. 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. 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 a of at least 60° on 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. 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 disc (100) and the second disc (101). Method for producing a coated disc (100) according to 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 traffic on land, in the air or on water, 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.