Plate comprising a glass or glass-ceramic substrate with a coating and its use

Abstract

Plate (10) comprising a glass or glass-ceramic substrate (100) with a top side (101) and a bottom side (102) and a coating (20), wherein the glass or glass-ceramic is transparent and uncolored, wherein the coating (20) is arranged in at least one region (30) of the glass or glass-ceramic substrate (100) on at least one side (101, 102) of the glass or glass-ceramic substrate (100), wherein the coating (20) comprises a pigment comprising pigment particles, wherein the plate (10) in the at least one region (30) of the glass or glass-ceramic substrate (100) in which the coating (20) is arranged, an L* value of at least 70, measured against a white tile through the glass or glass-ceramic substrate (100), a light transmittance between at least 0.1% and 8% and a spectral transmittance PvK for electromagnetic radiation of at least 55% at 1600 nm wavelength each based on a thickness of the glass or glass-ceramic substrate (100) of 4 mm, has.

Description

Field of the invention

[0001] The invention relates generally to a plate, in particular a cover plate, comprising a glass or glass-ceramic substrate with a top side and a bottom side and a coating, and to the use of such a plate. Background of the invention

[0002] Plates, especially cover plates, comprising a glass or glass-ceramic substrate are often provided with coatings. A cover plate is understood to be a disc-shaped body that separates two areas from each other. For example, a cover plate as part of an electronic component (the first area) can cover electronic components of this component and protect them from mechanical and environmental influences from the environment (i.e., the second area).

[0003] A coating on such a plate, for example, a cover plate, can serve purely functional purposes, for example, as a conductive coating, or be applied for more aesthetic reasons, such as to create a specific color impression. However, a compromise between functional and more aesthetic considerations is usually necessary.

[0004] This is particularly the case when the glass or glass-ceramic substrate is transparent and uncolored. In this case, the panel typically includes at least one coating intended to at least obscure the view of the area behind the panel. In addition to this primarily aesthetic function, the coating generally has a number of additional requirements depending on the panel's application.

[0005] If, for example, the plate is used to cover electronic components of a component, it may be necessary for a coating which is intended to at least make it difficult to see these components, to interact with these electronic components in a certain way or to be designed in such a way that it does not have a disruptive influence on their function.

[0006] For example, it is known to use capacitive touch sensors. A coating applied to a plate covering such touch sensors must therefore not only fulfill a transparency-reducing function and possibly exhibit a specific color coordinate, but must also exhibit only low conductivity, at least in the areas where touch sensors are installed.

[0007] Possible further requirements for such coatings concern the resistance to materials used, for example, for bonding components, or the impermeability of the coating.

[0008] Special requirements exist for coatings applied to a display area of ​​a panel. For example, European patent application EP 1 867 613 A1 describes a coating formed from a fired precious metal preparation and having an electrical sheet resistance of more than 1 MΩ / m. 2 This coating enables the color display of light sources arranged under a viewing window (i.e., in a display area) and simultaneously allows the use of capacitive touch sensors. However, such coatings are very expensive due to the precious metal content.

[0009] European patent application EP 2 223 900 A1 proposes another coating for a display area of ​​a glass or glass-ceramic panel. The proposed coating is obtained from a sol-gel ink and preferably comprises pigments and fillers in addition to alkyl silicates. The coatings proposed in EP 2 223 900 A1 do not contain any precious metal and are therefore significantly cheaper to produce.

[0010] Although the coatings described in EP 2 223 900 A1 offer a number of advantages and, for example, enable the use of touch sensors, they also have a number of disadvantages. In particular, it has been shown that the described layers are not suitable for use with optical sensors for detecting the temperature of cookware. Furthermore, the use of multi-color or multi-color display elements with the prior-art coatings is difficult. In particular, the prior-art layers exhibit rather low brightness.

[0011] Furthermore, the pigment content in the coatings according to EP 2 223 900 A1 results in significant scattering. The scattering of the coatings varies in intensity.

[0012] German patent DE 10 2018 122 020 B3 relates to a glass or glass-ceramic article that is at least partially coated with a nanoscale layer comprising a metallic material. The nanoscale layer does not comprise a pigment.

[0013] The German patent application DE 10 2010 032 113 A1 relates to transparent or transparent colored lithium aluminum silicate glass ceramics.

[0014] European patent EP 2 614 099 B1 relates to a polyurethane coating with low transmission in the wavelength range of visible light for display areas on glass, glass-ceramic or plastic molded bodies, in particular for display areas of cooking surfaces or control panels of household appliances.

[0015] There is therefore a need for plates, for example cover plates, comprising a glass or glass-ceramic substrate and a coating with a homogeneous, light color impression, in which infrared sensors arranged in the area of ​​the plate in which the coating is arranged can be used to detect the temperature of cookware.

[0016] The object of the invention is therefore to provide a plate, in particular a cover plate, comprising a glass or glass-ceramic substrate and a coating that overcomes or at least mitigates the aforementioned weaknesses of the prior art. A further aspect of the invention relates to the use of such a plate.

[0017] The object is achieved by the subject matter of the independent claims. Preferred and specific embodiments are found in the dependent claims.

[0018] The disclosure thus relates to a plate, in particular a cover plate, comprising a glass or glass-ceramic substrate with a top side and a bottom side and a coating, wherein the glass or glass-ceramic is transparent and uncolored, wherein the coating is arranged in at least one region of the glass or glass-ceramic substrate on at least one side of the glass or glass-ceramic substrate, wherein the coating comprises a pigment comprising pigment particles, wherein the plate in the at least one region of the glass or glass-ceramic substrate in which the coating is arranged, an L* value of at least 70, preferably at least 75, measured against a white tile through the glass or glass-ceramic substrate, a light transmittance between at least 0.1% and 8% and a spectral transmittance PvK for electromagnetic radiation of at least 55% at 1600 nm wavelength, each based on a thickness of the glass or glass-ceramic substrate of 4 mm, has.

[0019] A design of a plate, in particular a cover plate, has a number of advantages.

[0020] The design of the glass or glass ceramic as a transparent, uncolored material ensures that display elements can be perceived in true color, thus increasing operator safety. Furthermore, sufficient illumination is ensured even with only a low energy input.

[0021] The design of the coating in such a way that it includes a pigment allows for flexible adjustment of the coating's optical properties. The use of very expensive preparations containing precious metals is not necessary. Furthermore, this offers the advantage that the complex recovery of the precious metal during plate recycling is not necessary.

[0022] Because coatings according to embodiments of the plate according to the disclosure comprise a pigment, they are light-scattering coatings. This means that when determining the optical properties of a plate in which a coating comprising a pigment is arranged in a region of a surface of a glass or glass-ceramic substrate, scattering must also be taken into account. In particular, with regard to the transmission in this region of a plate according to embodiments of the disclosure, it is noteworthy that the total transmission results from direct or directed transmission and scattered or diffuse transmission.Unlike prior art panels, such as those described in EP 1 867 613 A1, where the transmission of electromagnetic radiation in the visible light range is adjusted in particular by the absorption of a coating and the scattering of the layer is so small that it does not need to be taken into account, in the present case it is less the absorption of the coating that is relevant, but in particular the ratio of the proportions of directed light and scattered light.

[0023] In other words, the use of a pigment makes it possible to create a coating that is scattering due to its pigment content, thus making it difficult to see through the panel. However, this does not necessarily increase the absorption of electromagnetic radiation in the coating.

[0024] This is particularly evident in the fact that the panel, in the at least one area in which the coating is arranged, has an L* value of at least 70, preferably at least 75, measured against a white tile through the glass or glass-ceramic substrate. The L* value, also called luminance, describes the brightness of a color in the CIELAB color space with values ​​from 0 to 100. In other words, the coating is a light coating. The value is obtained in a remission measurement against a white tile. The measuring device used is preferably the Spectrophotometer CM-700d from Konica-Minolta (SCI 10°, D65) or a Datacolor CHECK II Plus.

[0025] In particular, in the at least one region in which the coating is arranged, the plate has an a* value and a b* value with a value |a*| and |b*| of at most 10, preferably at most 8, particularly preferably at most 6. The values ​​of a* and b* describe the chromaticity of a color in the CIELAB color space. Colors close to the values ​​a* = 0 = b* are perceived as achromatic, i.e., as a grayscale.

[0026] A bright coating, i.e. a coating which has only a low, if any, absorption of electromagnetic radiation in the visible light range, i.e. from 380 nm to 780 nm, is particularly advantageous in combination with a substrate comprising a transparent, uncolored glass or a transparent, uncolored glass ceramic. In particular, such a bright coating, preferably with low chroma, enables the most color-fast representation of display elements through the glass or glass ceramic and the coating. In this way, user safety can be improved, as multi-color display elements can be used. This makes it possible, for example, to differentiate a dangerous state of a cooking appliance from a normal state by using a special warning color (e.g. red) for a display element and to visually mark it accordingly.

[0027] This is further supported by the fact that the plate has a light transmittance of at least 0.1% to 8% in the area of ​​the glass or glass-ceramic substrate in which the coating is arranged.

[0028] Within the scope of the present disclosure, the specified measured values ​​for transmission and / or scattering always refer to the observation of an area of ​​a plate in which only a coating according to the present disclosure and the glass or glass-ceramic substrate are arranged. It is certainly possible for the plate according to the present disclosure to have further coatings, for example decorative coatings (such as markings of functional areas) or functional coatings. Such further coatings can be arranged on the same side of the glass or glass-ceramic substrate as the coating according to the present disclosure and, for example, also completely or partially overlap with the coating according to the present disclosure, for example overlaying or underlaying this coating.However, such additional coatings may further influence the resulting, for example, optical properties of the plate and are therefore not taken into account in the context of the present disclosure when determining the transmittances, unless expressly stated otherwise.

[0029] The bright color location of the coating according to the present disclosure is advantageous, among other things, because in this way, a combination with bright, opaque coatings, such as those used, for example, as so-called underside coatings of cooking surfaces, ensures a particularly homogeneous color impression of the resulting panel. In particular, the combination of such a panel with IR cooking sensors and / or multi-color or multi-color display elements can not only increase operating comfort, but also further improve operator safety, since multi-color displays, which, for example, indicate the status of a cooking appliance, are particularly visible in this way.

[0030] For the purposes of this disclosure, the part of the electromagnetic spectrum visible to humans (visible light) is understood to be the wavelength range between 380 nm and 780 nm, as defined by DIN 5031-7. The range of electromagnetic radiation with wavelengths from 780 nm to 1 mm is referred to as infrared radiation. A further distinction is made between the IR-A range from 780 nm to 1400 nm, the IR-B range from 1400 nm to 3000 nm, and the IR-C range from 3000 nm to 1 mm.

[0031] The light transmittance is determined here according to DIN EN 410. A measuring arrangement is used in which the sample to be measured—here, the area of ​​a plate comprising a glass or glass-ceramic substrate in which the coating is arranged according to embodiments of the disclosure—is arranged in the sample chamber. The sample to be measured is located in the beam path between the light source and the integrating sphere at a specific distance from the entrance of the sphere. This distance is selected such that the entrance of the sphere defines an aperture angle of 2°. The value obtained in this way corresponds to the direct transmission component. The described measuring arrangement is used in the context of the present disclosure for both the light transmittance and the spectral transmittance PiP. This arrangement is also referred to as "PiP" or "sample in the sample chamber" in the context of the present disclosure.

[0032] The light transmittance measured in PiP configuration is a measure of the opacity of the panel. The lower the light transmittance, the more opaque the panel. Since adequate opacity is an essential characteristic of the panel, the light transmittance must be determined in PiP configuration and must not exceed 8%.

[0033] According to the present disclosure, the plate is designed such that, in the region in which the coating is arranged on the glass or glass-ceramic substrate, seeing through the plate to elements arranged behind the plate is at least made more difficult due to scattering. At the same time, however, the plate is designed such that, in this region, the plate is semi-transparent. This means that, in this region, it is possible to perceive, for example, illuminated elements in the switched-on state through the plate. For example, these illuminated or display elements can be LEDs, in particular LED 7-segment displays.

[0034] Furthermore, the plate is designed in such a way that the plate has a spectral transmittance PvK of at least 55% at a wavelength of 1600 nm in the area of ​​the glass or glass-ceramic substrate which is covered with the coating.

[0035] In other words, the plate according to the present disclosure has a relatively high transmission in the near infrared range. This is the total transmission, i.e. comprising both the directed and the scattered transmission, which is determined by measurement in a measuring arrangement in which the sample to be measured is arranged directly at the entrance of an integrating sphere. This arrangement is also referred to in the present disclosure as “PvK” or “sample in front of sphere”. A sensor for detecting the transmitted light component is attached to an exit of the integrating sphere arranged laterally at an angle of 90° to the beam path. This measuring arrangement therefore detects both the directly transmitted component and the scattered transmitted component of the light. The value measured in this way is referred to as the spectral transmittance PvK.

[0036] The spectral transmittance is a measure of the light-tightness of the plate. In principle, a plate can, for example, have a low light transmittance (PiP) and a high spectral transmittance PvK in the visible range. Such a plate would be opaque, but not light-tight, and would therefore be translucent or translucent. However, since the PvK value, as the total transmittance, always includes the PiP component of the transmission, a plate cannot have a low PvK and a high PiP value at the same time. If a plate is light-tight, i.e., opaque, it is consequently also opaque. For a non-scattering sample, the spectral transmittance PvK and the spectral transmittance PiP are identical.

[0037] According to one embodiment, the plate is designed such that in the wavelength range from 380 nm to 780 nm, the spectral transmittance PvK at a specific wavelength is always higher, preferably at least 1% higher, particularly preferably at least 2% higher, and particularly preferably at least 4% higher, than the spectral transmittance PiP at the same wavelength. At least 1% higher means that the difference between the spectral transmittance PvK and the spectral transmittance PiP at a specific wavelength is at least 1%. In other words, the scattering at this wavelength in the sense of the scattering coefficient described below is Fig. 6 and Fig. 7 at least 1%.

[0038] This means that the plate is only truly opaque in the region of the glass or glass-ceramic substrate in which the coating is arranged according to embodiments of the disclosure if an element, the view of which is to be reduced or even completely prevented through the plate, is not only arranged behind this plate as seen from the viewer, but also at a distance from it. However, if the element were pressed against the plate in such a design, it would be visible from the front.

[0039] At wavelengths of less than 400 nm, for example, glass ceramic absorbs light significantly, so that scattering is lower in this range, since scattering is defined in the context of the present disclosure as the scattered portion of the transmission.

[0040] For elements designed as IR sensors, typical distances to the plate range from 1 mm to several centimeters.

[0041] Since optical temperature sensors do not contain imaging optics, their functionality is determined solely by the total transmittance, i.e., the PvK value. It doesn't matter whether the total transmittance has a high PiP component in the infrared range or not, as long as the PvK value is sufficiently high.

[0042] The spectral transmittance refers to the value of the transmission at a single wavelength according to the definition in DIN 5036-1.

[0043] A high transmission in the near infrared range as provided according to the present disclosure is advantageous because it enables the use of various optoelectronic IR sensors, such as those used for measuring the temperature of the bottom of cookware in cooking hobs.

[0044] For the purposes of this disclosure, the following definitions apply: A glass is understood to be a material which is obtained from a melt and which is amorphous, in particular X-ray amorphous.

[0045] A glass-ceramic is understood to be a material obtained from a precursor glass by a controllable, particularly controlled, crystallization. In particular, the crystallization of the glass to form a glass-ceramic, also referred to as ceramization, can include the steps of nucleation and nucleus growth.

[0046] Such a glass-ceramic can, for example, contain the following components in wt.% on an oxide basis: Li2O 2.5 to 5.5 Σ (Na2O + K2O) 0.1 to less than 4 MgO 0 to 3 Σ (CaO + SrO + BaO) 0 to 5 ZnO 0 to 4 B2O3 0 to 3 Al2O3 16 to 26 SiO2 58 to 72 TiO2 1.5 to 5.5 ZrO2 0 to 2.5 SnO2 0.1 to less than 0.7 Σ (TiO2 + ZrO2 + SnO2) 3 to 6.5 P2O5 0 to 5 Fe2O3 0 to 0.025

[0047] In the context of the present disclosure, a glass or a glass ceramic which is transparent and uncolored is understood to mean a glass or a glass ceramic which has no coloration in the visible light range of the electromagnetic spectrum, but rather a neutral color location, and which also has only a low absorption of electromagnetic radiation in the visible light range of the electromagnetic spectrum from 380 nm to 780 nm, i.e. a light transmittance of at least 80%, and which also has only very low scattering.

[0048] In contrast to a transparent, uncolored material, the present disclosure thus refers to a material which, although transparent, has a high absorption of electromagnetic radiation in the visible light range of the electromagnetic spectrum, as well as a material which has a strong scattering of electromagnetic radiation in the visible light range of the electromagnetic spectrum.

[0049] Transparent materials are thus in contrast to, for example, opaque or translucent materials. Uncolored materials are in contrast to materials that exhibit strong absorption in the visible light range. Of course, a material can be both highly scattering and highly absorbent. In this case, a material thickness of 4 mm is used with regard to scattering, absorption, and / or opacity or translucency.

[0050] A transparent, uncolored glass-ceramic preferably contains no coloring compounds, except for unavoidable traces, such as V2O5, CoO, MoO3, MnO2, Cr2O3, CeO2, and Nd2O3. Unavoidable traces refer to a component content of no more than 500 ppm.

[0051] Where reference is made to optical properties of materials and / or products in the context of this disclosure, this refers, unless expressly stated otherwise, to a material thickness of 4 mm.

[0052] A plate is understood to be a product in which the lateral dimension in a first spatial direction of a Cartesian coordinate system is at least one order of magnitude smaller than the lateral dimensions in the two other spatial directions perpendicular to the first spatial direction. This first lateral dimension is referred to as the thickness in the context of the present disclosure, and the lateral dimensions in the two other spatial directions are referred to as the length and width. The length and width can be of the same order of magnitude.

[0053] The length and width of the panel determine the main surfaces or main areas of the panel. These are the top and bottom of the panel. The top side of the panel is the main area of ​​the panel which faces the user during operational use. The bottom side is the main area of ​​the panel which faces away from the user during operational use. During operational use, the panel can essentially be arranged lying down, for example resting horizontally on a base. However, if the panel is arranged upright, for example vertically, the "top side" of the panel is understood to be the front side of the panel - facing the user - and the bottom side is understood to be the back side of the panel - facing away from the user.The top and bottom of the plate are essentially parallel to each other.

[0054] For the purposes of the present disclosure, a pigment is understood to be a coloring agent or colorant comprising particles, so-called "pigment particles," wherein these particles are insoluble in a surrounding medium and impart a visually perceptible impression, for example, a color impression and / or an effect, to the medium. Pigment particles have lateral dimensions, for example, diameters, of up to 100 µm or even 200 µm, for example, although the exact lateral dimensions can vary depending on the intended use. The geometric shape of the particles can also vary greatly.

[0055] In the context of the present disclosure, a substrate is understood to be a product, for example a plate, whose surface is to be treated, for example by applying a coating. In particular, a substrate is thus to be understood as a base for a coating applied thereto. The coating can also completely envelop the substrate. However, it is also possible for the coating to be applied only to one area of ​​the surface, for example, only to one of the main surfaces of the substrate, or even only to an area of ​​one of the main surfaces.

[0056] In the context of the present disclosure, a coating is understood to mean a layer of material which has been applied to a surface by means of a coating process.

[0057] If, within the scope of the present disclosure, pigments are described in which the pigment particles comprise a substrate and a coating, the substrate comprised by the pigment particle is referred to as the "pigment substrate" and the coating comprised by the pigment particle is referred to as the "pigment coating." In contrast, the glass or glass-ceramic substrate comprised by the plate and the coating arranged in at least one region of the glass or glass-ceramic substrate on at least one side of the glass or glass-ceramic substrate are referred to as the "coating."

[0058] Pigment substrates and glass or glass-ceramic substrates differ not only in their composition but also in their spatial dimensions. In particular, pigment particles—and thus also the pigment substrate and the pigment coating—have significantly smaller dimensions (e.g., a significantly smaller thickness, width, and length) than the glass or glass-ceramic substrate. This also applies correspondingly to the coating arranged in at least one area of ​​the glass or glass-ceramic substrate on at least one side of the glass or glass-ceramic substrate: This coating has significantly larger dimensions than the pigment coating.

[0059] If, within the scope of the present disclosure, the term "maximum lateral dimension" is used to describe the spatial and physical extent of a pigment particle, this may mean, for example, in the case of a pigment formed from platelet-shaped pigment particles, that only the length of the pigment particle is specified, provided the pigment particle is formed as a platelet with an approximately rectangular base area. If, in this case, for example, the maximum lateral dimension is specified as "10 µm to 60 µm," this would mean that this pigment is formed from pigment particles that have a length of, for example, 10 µm. The width in this case may, for example, be only 5 µm, but not more than 10 µm.However, it is also possible for the platelets to be cylindrical or approximately cylindrical in shape, such that the maximum lateral dimension describes the diameter of this (very thin) cylinder. Commercially available effect pigments comprising platelet-shaped pigment particles are generally defined in terms of their size by specifying the diameter of the platelet, i.e., the surface diameter of a main surface. In the context of the present application, this manufacturer's specification regarding the particle size is understood to be equal to the maximum lateral dimension of the particle specified in the context of the present application, for example, the diameter of a main surface of the particle.Unless expressly stated otherwise, the diameter of the particle in the context of the present disclosure is not understood to mean the so-called equivalent diameter of a particle usually stated for color pigments, which, however, for spherical particles corresponds to the diameter of the maximum lateral dimension stated here.

[0060] According to one embodiment of the disclosure, the pigment particles comprised by the pigment comprise a pigment substrate and a pigment coating, wherein the pigment substrate comprises an oxidic material and is preferably platelet-shaped. Preferably, the pigment substrate comprises SiO2 and / or Al2O3. Particularly preferred is an embodiment in which the pigment substrate comprises silicate glass and / or a layered silicate.

[0061] A silicate glass is a glass containing SiO2. A layered silicate is a crystalline solid containing SiO2.

[0062] In the context of the present disclosure, a platelet-shaped formation is understood to mean a formation of a particle which has two main surfaces which are aligned essentially parallel to one another in such a way that the straight lines formed by the normal vectors of the main surfaces enclose an angle of no more than 10°, preferably no more than 5°. These main surfaces are determined by lateral dimensions in the two spatial directions of a Cartesian coordinate system, which are perpendicular to the third spatial direction, the thickness of the particle. These lateral dimensions perpendicular to the thickness are often also referred to as length and width, where the length is generally the maximum lateral dimension and the width can be less than the length but is at least as great as the thickness.In a special case of platelet-shaped particles, the length and width can be equal, so that the main surface assumes a square or even round shape. In the latter case, the maximum lateral dimension could also be referred to as the diameter of the particle.

[0063] The maximum lateral dimension of the particle in the two spatial directions of a Cartesian coordinate system perpendicular to the thickness is at least twice, preferably at least five times, and particularly preferably at least ten times the thickness.

[0064] The ratio of the maximum lateral dimension to the thickness is also referred to as the aspect ratio of the particle. A platelet-shaped particle with two essentially parallel main surfaces is therefore understood to mean that the aspect ratio is at least 2, preferably at least 5, and particularly preferably at least 10. Aspect ratios of pigment particles that are particularly suitable for coatings are generally no more than 200.

[0065] In other words, according to this embodiment, the pigment particles are formed as a coated product.

[0066] Such an embodiment is advantageous because it allows the properties of the coating to be adjusted particularly easily. For example, it is possible for the pigment particles to be designed in such a way that the pigment coating ensures or will ensure particularly good compatibility between the other components of the coating, such as the matrix, the binder, or fillers. Alternatively or additionally, however, it is also possible for the pigment coating to influence the optical properties of the pigment or the pigment particles comprised by the pigment, for example by specifically adjusting a color location and / or the composition of the pigment coating.Of course, it is also possible that the same measure, for example the targeted adjustment of the composition of the pigment coating, can influence both the compatibility between the pigment and other components of the coating and the optical properties.

[0067] For example, a black color impression of a pigment can be achieved by a pigment coating that includes Fe3O4, which can also influence the interaction with the matrix of the coating, for example, leading to faster setting of the binder.

[0068] It has been shown that the possible platelet-shaped formation of the pigment substrate - correspondingly, the pigment particle as such is also platelet-shaped - can be particularly advantageous for the formation of well-adhering, scratch-resistant layers.

[0069] Preferably, the platelets are positioned parallel to the surface of the glass or glass-ceramic substrate.

[0070] The pigment substrate preferably further comprises an oxidic material. This serves, on the one hand, to ensure sufficient temperature stability of the coating of the glass or glass-ceramic substrate and, accordingly, also of the plate of the present disclosure.

[0071] Advantageously, the pigment substrate comprises SiO2 and / or Al2O3. In particular, the pigment substrate can consist entirely or partially of SiO2 or Al2O3. However, it is also possible for the pigment substrate to comprise SiO2 and / or Al2O3 only to a certain extent, for example, 10 wt.%, 50 wt.%, or 90 wt. SiO2 and Al2O3 are thermally and chemically very stable materials and are therefore suitable for the production of products that exhibit high temperature resistance. Furthermore, these materials are transparent in the visible light range of electromagnetic radiation and also exhibit sufficient transmission for electromagnetic radiation in the infrared range, particularly in the near infrared range.

[0072] Particularly preferred is an embodiment of the plate in which the pigment substrate comprises a silicate glass and / or a layered silicate. Since the plate comprises a glass or glass-ceramic substrate, the compatibility of the coating with the glass or glass-ceramic substrate can be further improved by configuring the pigment substrate to comprise a silicate glass and / or a layered silicate, particularly with regard to the adhesion and scratch resistance of the coating to the glass or glass-ceramic substrate.

[0073] In particular, the layered silicate can be formed as mica, for example as muscovite, in particular as light, uncoloured mica.

[0074] According to a further embodiment, the pigment particles have a maximum lateral dimension, for example a diameter of a main surface, between at least 5 µm and at most 25 µm.

[0075] This means, for example, that the length or width of the pigment particle is between at least 5 µm and at most 25 µm. If the platelet is approximately round, the maximum lateral dimension can also be understood as the diameter of a main surface of the pigment particle, which in this case is between at least 5 µm and at most 25 µm. The thickness of the pigment particles is generally at or below 1 µm. Therefore, according to one embodiment of the plate, particularly preferred aspect ratios of pigment particles are between at least 5 and at most 50.

[0076] Pigment particles with larger lateral dimensions lead to strong scattering of electromagnetic radiation, especially in the infrared range, and are therefore unfavorable.

[0077] If the coating is applied by means of a screen printing process, it is also advantageous to use pigments in which the pigment particles have a maximum lateral dimension, for example a diameter of a main surface, of at most 25 µm, because in this way the use of screens with a finer mesh side and thus the production of both thinner layers and finer structures is possible.

[0078] According to a further preferred embodiment of the plate, the pigment or pigment particles comprise less than 1 wt.% Fe2O3 and / or less than 1 wt.% SnO2. According to a further embodiment of the plate, the pigment or pigment particles are particularly preferably free of Fe2O3 except for unavoidable traces. Unavoidable traces here mean a content of Fe2O3 due to always occurring impurities and are at most 500 ppm.

[0079] Fe2O3 generally causes a material to color in the visible light range of electromagnetic radiation. A Fe2O3 content of more than 1 wt.% would therefore, on the one hand, lead to a color cast of the pigment particles and thus also of the coating, which is detrimental to the most accurate color representation of display elements below the area of ​​the plate where the coating is located. Furthermore, Fe2O3 absorbs in the IR range of the electromagnetic spectrum. This has a correspondingly adverse effect on transmission in this range and thus on the use of certain sensors.

[0080] Preferably, the pigment or pigment particles are free of Fe2O3 except for unavoidable traces. Preferably, the pigment or pigment particles contain at most 500 ppm of Fe2O3.

[0081] SnO2 also absorbs electromagnetic radiation across the entire wavelength range from 500 nm to 2500 nm. For this reason, the SnO2 content of the pigment or pigment particles is advantageously limited to a maximum of less than 1 wt.%.

[0082] According to a further embodiment of the plate, the coating comprises at most 1 wt.% graphite.

[0083] Graphite is a component of coatings that is used, for example, to adjust the color coordinate, but also to achieve sufficient scratch and abrasion resistance of the coating and / or to adjust its conductivity. Furthermore, graphite also acts as a lubricant and distributes very well into the gaps that arise in the coating between the stacked platelet-shaped pigment particles. Therefore, graphite also increases the impermeability of the layer. As explained above, however, a light color coordinate of the coating is advantageous for the most unadulterated representation of display elements. Furthermore, such a design also means that when the coating is combined with another coating, such as a light, opaque coating, a homogeneous overall impression of the panel can be achieved.This is aesthetically preferable, but given that color representations of a device's malfunction are more noticeable in such a homogeneous surface, such a design also increases the operator safety of a device that includes such a plate. Since graphite is highly absorbent, the graphite content must be limited to create a bright coating and achieve a homogeneous, bright color impression of the plate. The conductivity of the coating should also be as low as possible to enable the use of capacitive touch sensors.

[0084] According to a further embodiment of the disclosure, the light transmittance of the plates in the region of the glass or glass-ceramic substrate in which the coating is arranged is at least 0.5%, preferably at least 1%. This is advantageous for further improving operator safety, as it allows for the realization of a sufficiently bright user interface. Preferably, the light transmittance should be less than 5%, particularly preferably less than 4%. Otherwise, elements arranged beneath the plate may still be disturbingly visible.

[0085] According to yet another embodiment of the disclosure, the spectral transmittance PvK of the plate in the region of the glass or glass-ceramic substrate in which the coating is arranged is at least 30%, preferably at least 45%, and particularly preferably at least 50%, in the wavelength range between 1 µm and 2 µm at each wavelength, particularly preferably at least 60%, preferably at least 65%, at a wavelength of 1600 nm. This is advantageous for the use of certain infrared sensors, in particular InGaAs-based optoelectronic infrared sensors. These are particularly sensitive in the wavelength range of electromagnetic radiation between 1 µm and 2 µm.

[0086] Infrared sensors with high sensitivity in the range between 1 µm and 2 µm can be used, for example, as IR cooking sensors. They can also be used in interfaces for optical data communication. Such interfaces are used, for example, for communication between household appliances, such as between a cooking appliance and an extractor hood. Alternatively or additionally, a service interface can also be equipped with such an infrared sensor so that a technician on-site can, for example, read error data from a defective appliance or transmit corrected settings to the appliance.

[0087] A cooking sensor is a sensor for detecting the operating status of a cooking appliance or for monitoring a cooking process. In particular, this includes a sensor for measuring the temperature of the bottom of cookware.

[0088] According to one embodiment of the plate, the spectral transmittance PvK of the plate for electromagnetic radiation in the region of the glass or glass-ceramic substrate in which the coating is arranged is at least 30%, preferably at least 35% and particularly preferably at least 40% at at least one wavelength in the wavelength range between 850 nm and 1000 nm, preferably at a wavelength of 940 nm.

[0089] Such a plate design is particularly preferable when silicon-based infrared sensors are to be used. These are used, for example, in so-called time-of-flight sensors for contactless input devices for gesture or proximity control, such as the VL6180X from ST Microelectronics. The spectral range between 850 nm and 1000 nm is particularly relevant here. High transmission in this wavelength range is particularly advantageous for gesture control, because gestures can then be detected at a greater distance from the outside of the separating element, in this case the plate. Other applications of silicon-based infrared sensors include receivers for signals from remote controls or communication interfaces for optical data transmission for communication between household appliances or for service interfaces.

[0090] According to a further embodiment of the plate, the light scattering of the plate in the region of the glass or glass-ceramic substrate in which the coating is arranged is less than 15% at 400 nm and / or the scattering of the plate for electromagnetic radiation at 800 nm is less than 35%. According to this embodiment, the light scattering in the visible spectral range is thus as low as possible, as is the case at 800 nm, i.e., immediately above the visible spectral range.

[0091] Such a design means that, for example, so-called 7-segment displays can be displayed sharply, i.e. they can be easily perceived by a viewer through the plate.

[0092] According to a further preferred embodiment of the plate, the spectral transmittance PvK of the plate for electromagnetic radiation in the region of the glass or glass-ceramic substrate in which the coating is arranged is at least 10%, preferably at least 20% and particularly preferably at least 30% and at most 50% in the wavelength range between 3.25 µm and 4.25 µm at at least one wavelength.

[0093] Such a design is particularly advantageous when the plate is used, for example, as a cover plate or separating element that is exposed to high thermal loads during operation. This can be the case, for example, when the plate is used as a cover plate in a cooking appliance, i.e. as a so-called hotplate. Such a design is particularly advantageous when bolometers are to be used as temperature sensors for detecting the temperature of the bottom of a cooking vessel. A hot cooking vessel behaves approximately like a blackbody radiator. When used properly, temperatures in the range of approximately 50 °C to approximately 200 °C occur at the bottom of the cooking vessel. In the case of improper use, for example when heating an empty cooking vessel or when the liquid in a cooking vessel has completely evaporated, significantly higher temperatures can arise. This can also result in an increased risk of fire.In the temperature range of proper and, above all, improper use, the base of the cooking vessel emits a significant amount of thermal radiation, including in the spectral range from 3.25 µm to 4.25 µm. Therefore, a design of the plate in which the spectral transmittance PvK of the plate for electromagnetic radiation in the region of the glass or glass-ceramic substrate in which the coating is arranged is at least 10%, preferably at least 20%, and particularly preferably at least 30% and at most 50% for at least one wavelength in the wavelength range between 3.25 µm and 4.25 µm leads to increased detection efficiency of such a sensor. Using such a temperature sensor, excessive heating of both the plate and the area surrounding the plate can be prevented. For example, this makes faster cooking possible and reduces the energy consumption of a cooking appliance.Furthermore, such a design can also enable improved cooking, since the energy transfer to a cooking vessel—depending on its precise design—is also more direct, thus enabling a more direct response of the food to the cooking appliance's power control. In any case, this increases the operational reliability of the cooking appliance.

[0094] Furthermore, using IR cooking sensors, it is possible to at least partially automate cooking processes. For this purpose, an IR sensor can be designed as part of a household appliance's control circuit, which can be used, for example, to maintain a specific temperature of a cookware for a preset time or to vary it in a targeted manner. Such partial automation can also serve to increase operational safety, as deviations from proper use can be quickly detected and countermeasures can be taken.

[0095] According to a further embodiment of the plate comprising a glass or glass-ceramic substrate and a coating, the plate comprises a further coating, wherein the further coating is arranged in at least one region of the glass or glass-ceramic substrate on at least one side of the glass or glass-ceramic substrate, preferably on the same side as the coating. The further coating comprises a pigment comprising pigment particles. In the at least one region of the glass or glass-ceramic substrate in which the further coating is arranged, the plate has a light transmittance of between at least 0.001% and at most 2%, preferably between at least 0.01% and at most 1%. The further coating has a recess, which preferably forms a window, wherein the coating is arranged at least partially or over the entire surface at least in the region of the recess of the further coating.The color difference ΔE of the color locations of the coating and the further coating in the CIELAB color space, measured through the glass or glass-ceramic substrate, is in the range from more than 0 to 5, preferably in the range from more than 0 to 4, particularly preferably in the range from more than 0 to 2 and in particular in the range from more than 0 to 1. In the context of the present disclosure, a window is a recess with an area having a size of at least 0.1 cm. 2 , preferably at least 0.5 cm 2 and particularly preferably at least 1 cm 2 and are usually no larger than 100 cm 2 on.

[0096] In this embodiment, the optical properties and transmittances of the plate are also expressly determined for areas in which not only the glass or glass-ceramic substrate and a first coating are applied, but also a further coating.

[0097] According to this embodiment, it is possible for the coating and the further coating to at least partially overlap, i.e. to be superimposed or subordinate to one another, for example in an edge region of a recess, such as a window.

[0098] The color difference ΔE is given by the following formula: ΔE=(L1*−L2*)+(a1*−a2*)+(b1*−b2*)2.

[0099] Such a design of the plate is advantageous because it creates a particularly homogeneous color impression, which, for example, improves the perceptibility of displays indicating a malfunction of an appliance, such as a cooking appliance, since color differences are more easily perceived in a homogeneously colored plate.

[0100] In general, the color difference ΔE can be understood as a measure of the difference in a color impression. The larger this value, the more clearly the color locations differ. If the ΔE between two color locations is more than 5, the color locations are assessed as different colors. A value between 4.0 and 5.0 already represents a significant color difference that is rarely tolerated. At values ​​between 2.0 and 4.0, the color difference is perceived but generally tolerated. Values ​​between 1.0 and 2.0 represent a slight color difference. At values ​​between 0.5 and 1.0, the color difference is only noticeable to a trained eye. At values ​​between 0.0 and 0.5, the color difference is almost imperceptible.

[0101] The additional coating may be a coating that is, in particular, a thicker and therefore less translucent variant of the coating. In particular, the additional coating may comprise the same pigments as the coating, but may, for example, contain a lower binder content.

[0102] It is also possible for the further coating to be obtained from an application material, such as a printing ink, which comprises the same pigments, possibly also in corresponding mixing ratios, as the application material with which the coating is obtained, and which also comprises a comparable binder content, but the two application materials, such as printing inks or pastes, are different. However, in this case, the application material, such as the printing ink or paste, from which the further coating results, contains less solvent.

[0103] A further coating comprising the same pigments as Example 1, wherein the coating material, here a printing ink, contained less solvent and a thicker screen was used during application - here the screen printing process - results in a thicker layer with a correspondingly lower transmission.

[0104] The following color values ​​are obtained for such a layer: L* = 70.8, a* = -1.1, b* = 3.9. The light transmittance is approximately 1%.

[0105] According to yet another embodiment of the plate, the coating is arranged in at least one region of the underside of the glass or glass-ceramic substrate. The plate comprises a functional coating which is not in direct contact with a main surface (i.e., the top or bottom) of the glass or glass-ceramic substrate. The functional coating preferably comprises a pigment comprising pigment particles. The functional coating is applied to the coating and / or the further coating at least in a partial region. The light transmittance of the plate in the region in which the functional coating is arranged is between a minimum of 10 -5% and at most 0.5%, preferably at most 0.1%. The functional coating has a recess which forms a window, wherein the coating is preferably arranged at least partially or over its entire area in the region of the recess and wherein furthermore the recess in the functional coating and the recess in the further coating preferably overlap one another at least partially, wherein the functional coating, measured on the surface of the functional coating, preferably has an L* value of more than 40, preferably more than 50 and particularly preferably more than 60.

[0106] In this embodiment, too, the optical properties and transmittances of the plate are expressly determined for areas in which not only the glass or glass-ceramic substrate and a first coating are applied, but also a further coating.

[0107] According to a further embodiment, the functional coating is a masking and / or sealing layer. In this case, a light transmittance of approximately 0.1% can be achieved with a further coating having a pigmentation according to Example 1, but obtained from a coating material containing less solvent.

[0108] If the functional coating is applied to another coating with color values ​​L* = 70.8, a* = - 1.1, b* = 3.9 and a resulting light transmittance of approximately 1% for this additional coating, a ΔE of 1.55 results between the area in which the coating and the area in which the additional coating and a functional coating, such as a sealant, are applied.

[0109] A sealing layer is a layer that is impermeable in the sense that it acts as a barrier against the entry and passage of fluids such as water, oil, and / or water vapor, or other aqueous liquids. A masking layer is a layer that significantly reduces the transmission of visible light.

[0110] The present disclosure further relates to a cooking appliance comprising a plate according to embodiments of the present disclosure, as well as the use of a plate according to embodiments of the present disclosure as a cover plate or partition plate or as a partition element, for example as a viewing window in an oven, or as a cooking plate in a cooking appliance, as a fireplace viewing window, as a radiator cover or as a housing component of electronic devices such as mobile phones. Examples

[0111] The invention is further explained below with reference to figures and examples. They show: Fig. 1 to 5 transmission spectra in different wavelength ranges for a comparative example and an example of a plate according to the present disclosure as well as for two uncoated substrates comprising glass and glass ceramic, respectively, Fig. 6 and Fig. 7 Scattering spectra in different wavelength ranges for a comparative example and an example of a plate according to the present disclosure, and Fig. 8 is a schematic representation of a plate according to an embodiment.

[0112] In the figures, the transmission spectra of identical or corresponding glass or glass-ceramic plates are each designated by the same reference number.

[0113] Semitransparent coatings comprising effect pigments are known from the prior art, for example from documents EP 1 867 613 A1 and EP 2 223 900 A1. Such semitransparent coatings comprise mixtures of binders, various effect pigments, graphite, and fumed silica. Alkyl silicates, in particular, can be used as binders. Fumed silica can be used as a filler and rheology additive.

[0114] Effect pigments are pigments, i.e. colorants, which comprise particles and impart an effect to a medium, for example a coating material or a resulting coating, for example a so-called "metallic effect", as is known, for example, from car paints. This "metallic effect" can be promoted or further enhanced by a platelet-shaped formation of the pigment particles. The effect pigments can also impart an additional color impression to a medium, for example a coating material or a coating resulting from the coating material. In the simplest form, such effect pigments can be formed, for example, as metallic particles, for example as metallic platelets, for example as aluminum platelets.

[0115] However, the prior art documents primarily describe effect pigments in which the pigment substrate is a layered silicate, specifically mica, preferably uncolored mica. Metallic pigment substrates or metallic effect pigments are particularly unsuitable for semitransparent layers because they are opaque.

[0116] Mica-based phyllosilicates, which are suitable for use in so-called "semi-transparent" coatings, are available, for example, under the "Iriodin" brand from Merck KGaA. The use of Iriodin® 103, 111, 123, and 323 is described.

[0117] The Iriodin® 100 series pigments are pigments in which the pigment coating is preferably uncolored in the visible light range of the electromagnetic spectrum. These are therefore pigments which, on their own, create a white or silvery coating appearance. For example, Iriodin® 103 is also referred to as "rutile sterling silver." This optical coating appearance is particularly created by a pigment coating comprising a material which is non-absorbent in the visible spectral range and has a high refractive index. Examples of materials which such a pigment coating can comprise or from which such a pigment coating can consist are, in particular, TiO2 and SnO2, with TiO2 generally being chosen as the main component or even the sole component of such a pigment coating.

[0118] The Iriodin® 300 series, such as Iriodin® 323, on the other hand, generally have a pigment coating that exhibits a certain inherent color. Accordingly, Iriodin® 323, described for transparent coatings, is also known as "Royal Gold Satin," and thus exhibits a yellowish-gold color appearance. This color appearance is unfavorable for producing a semi-transparent coating that is as light as possible and preferably also color-neutral, which enables the most authentic color perception possible, and should therefore be avoided. The color appearance is particularly due to the fact that the pigment coating of Iriodin® 323 comprises a significant amount of Fe2O3. As already explained above, the high Fe2O3 content of this pigment alone makes its use in the coatings of panels according to the present disclosure unfavorable.In the context of the present disclosure, a significant content is defined as a content which is more than 10% by weight.

[0119] However, it has been shown that the use of these pigments known for semi-transparent coatings, in particular Iriodin® 103, 111, 123, and 323, is disadvantageous, especially when addressing applications that place high demands on the transmission of panels provided with coatings comprising such semi-transparent coatings, for example, to improve operator safety and / or operator comfort. For example, the coatings described in the prior art have the disadvantage that they have a relatively low overall transmission in the near infrared, particularly in the range between 1000 nm and 2000 nm, and are therefore unsuitable, for example, for use with IR cooking sensors.

[0120] For example, document EP 1 867 613 A1 shows in the Fig. 4 The scattering of two layers containing effect pigments in the wavelength range from 300 nm to 900 nm. The scattering of these layers at 850 nm is less than 40%.

[0121] The lightest and most color-neutral layer known from the prior art corresponds to layer D according to document EP 2 223 900 A1. It has a color value L* of 67.2 and, in addition to the binder and filler silica and graphite, comprises the effect pigments Iriodin® 111 and 103. Fig.Figure 4 of EP 2 223 900 A1 shows the transmission spectra for the layers B, C, D and E described therein in an arrangement for determining the total transmission, i.e. the spectral transmittance PvK in the range from 300 nm to 1000 nm. In the range from 850 nm to 1000 nm, the transmission for coatings B, D and E is less than 40%. For sample C, the transmission is higher in this range, but Fig.6 of EP 2 223 900 A1, when showing the corresponding scattering spectra for coatings B, C, and D, shows that C has high scattering in the visible range, amounting to approximately 16% at 400 nm and overall between approximately 10% and approximately 30%. Lines B and D show that the corresponding panels coated in this way have lower scattering in the coated areas of approximately 6% at 400 nm and approximately 5% to 15% across the entire wavelength range of visible light. This means that coating C, with more than 5%, has a light transmittance (PiP) that is too high to effectively prevent vision through the panel. The other coatings, on the other hand, have too low a transmission in the infrared range beyond 1,000 nm and are therefore not suitable for use with corresponding sensors for detecting the temperature of the bottom of cooking vessels. All layers have an L* value of less than 70.

[0122] Although the coatings described above allow the use of IR touch sensors at 940 nm, these coatings are not bright enough and therefore result in comparatively high energy consumption if sufficient visibility of display elements is desired or required, particularly to ensure operator safety.

[0123] The following table compares Example D according to EP 2 223 900 A1, a comparative example exhibiting similar optical properties in the visible light range of the electromagnetic spectrum as Example D, and an example of a coating according to a particularly preferred embodiment of the disclosure. The layer according to the comparative example has the same binder, but the pigmentation differs. A glass-ceramic substrate with a thickness of 4 mm was used as the substrate in each case.

[0124] From the comparison of the properties of plates according to the example of the present disclosure as well as according to the comparative example and example D, it is clear that it is possible, by changing the composition of the coating, namely here the pigmentation, to leave the optical properties of a plate comprising a glass or glass-ceramic substrate in the region in which a coating is arranged essentially unchanged in the visible spectral range, but at the same time to increase the transmission in the near IR range. Table 1 Comparison of plates comprising coatings according to the prior art and according to the embodiment of the disclosure Characteristic Example D according to EP 2 223 900 A1 Comparison example Example 1 Binder [wt.%] 58,1 73,1 72,6 Iriodin 111 [wt.%] 25,3 2,9 0 Iriodin 103 [wt.%] 8,1 14,4 0 Iriodin 323 [wt.%] 0 2,9 0 Iriodin 119 [wt.%] 0 0 21,8 Graphite [wt.%] 3,3 1,8 0,9 Silica [wt.%] 5,2 4,9 4,7 Layer thickness [µm] 7,5 7,0 4,5 Spectral transmittance at 940 nm 38,7 % 37,6 % 44,1 % Suitability for IR touch sensors Yes Yes Yes Suitability for temperature sensors at 1600 nm No No Yes Suitability for capacitive sensors Yes Yes Yes Color values ​​white tile L* 67,2 69,0 77,3 a* 0,52 0,3 -0,5 b* 4,72 8,9 6,0 Transparency sufficiently reduced Yes Yes Yes Sufficiently permeable for display elements Yes Yes Yes Scattering at 400 nm 6% 10% 12% Scattering at 800 nm 26% 28% 32%

[0125] This is also confirmed by the attached Fig.1. This shows the comparison of the transmission spectra of the comparative example with those of the example according to the present disclosure in the wavelength range from 0 nm to 2500 nm, wherein the spectral transmittance PiP (i.e. measured in a PiP arrangement) and the spectral transmittance PvK (i.e. measured in a PvK measuring arrangement) are compared with one another. The transmission curves according to the present disclosure are shown in solid lines, while those according to the comparative example are shown in dashed lines. The curves of the total transmission (corresponding to the spectral transmittance PvK) are designated by the reference numerals 1 (for the transmission according to the present disclosure) and 2 (comparative example), and those for the direct transmission (spectral transmittance PiP) are designated by reference numerals 3 (for the plate according to the present disclosure) and 4 (comparative example).

[0126] Surprisingly, it has been shown that, due to the modified pigmentation, the direct transmission of the plate according to the present disclosure, in particular, in the region in which the coating is arranged, is virtually unchanged in the visible spectral range (380 nm to 780 nm wavelength of electromagnetic radiation), but increased in the infrared, particularly in the range from 1000 nm to 2000 nm wavelength. Both samples have a light transmittance of approximately 3%, which can be adjusted, for example, via the layer thickness of the coating.

[0127] This is also illustrated by the transmission spectra according to Fig.4. Here, the transmittance PvK and the spectral transmittance PiP for the 380 nm to 780 nm wavelength range of electromagnetic radiation are plotted against the wavelength. The spectral transmittance PiP is almost identical for the example according to the present disclosure and the comparative example, and spectra 3 and 4 are almost identical.

[0128] In this way, a plate can be obtained comprising a glass or glass ceramic substrate with a top side and a bottom side and a coating, wherein the glass or glass ceramic is transparent and uncolored, wherein the coating is arranged in at least one region of the glass or glass ceramic substrate on at least one side of the glass or glass ceramic substrate, wherein the coating comprises a pigment, and wherein the plates have, in the at least one region of the glass or glass ceramic substrate in which the coating is arranged, an L* value of at least 70, preferably at least 75, measured against a white tile, a light transmittance between at least 0.1% and 8% and a spectral transmittance for electromagnetic radiation of at least 55% at a wavelength of 1600 nm, in each case based on a thickness of the glass or glass ceramic substrate of 4 mm.

[0129] According to a particularly preferred embodiment, the pigment comprises a pigment substrate and a pigment coating, wherein the pigment substrate is preferably platelet-shaped and comprises an oxidic material, namely SiO2 and Al2O3. In this case, the pigment substrate is in the form of a layered silicate. In general, however, it is also possible for the pigment substrate to be a SiO2 or Al2O3 platelet, or to comprise a silicate glass, or to be in the form of a platelet made of a silicate glass. For example, in order to achieve a particularly good match of thermal expansion coefficients between the coating of the plate and the glass or glass-ceramic substrate, it may be advantageous to select a pigment comprising a specific pigment substrate, for example made of silicate glass. The optical properties of the resulting coating can also be influenced by the choice of pigment substrate.For example, coatings with pigments that comprise mica particles, such as mica flakes (i.e., flakes made of layered silicates), as a pigment substrate generally have a so-called "satin-matt" appearance, whereas pigment substrates made of silicate glass tend to produce more strongly reflective effects in the coating, for example, in the form of a strong sparkle. This also means, however, that the covering effect of the effect pigments can vary depending on the pigment substrate. The skilled person will therefore select the pigment to achieve the desired light transmittance and, if necessary, adjust the composition of the coating, for example, by skillfully adapting the fillers and other components.

[0130] The example according to the present disclosure comprises a coating which does not comprise any of the effect pigments described for semitransparent coatings according to the prior art. Instead, a pigment was used which - pigment particles with a maximum lateral dimension of at least 5 µm and at most 25 µm, and - less than 1 wt.% Fe2O3 and / or - less than 1 wt% SnO2.

[0131] A particularly suitable pigment, which is also encompassed by the coating of the plate according to the example of the present disclosure, is Iriodin® 119. This is an effect pigment comprising 56 wt.% mica, 43 wt.% TiO2, and less than 1 wt.% SnO2. The maximum lateral dimension is between at least 5 µm and at most 25 µm. The pigment substrate here is thus formed as mica particles, more precisely as mica platelets. Iriodin® 119 thus comprises pigment particles comprising a platelet-shaped pigment substrate.

[0132] A pigment such as Iriodin® 119, i.e. a pigment with a low SnO2 content of less than 1 wt.% and comprising pigment particles with a maximum lateral dimension of pigment substrate or pigment particles between at least 5 µm and at most 25 µm, is particularly suitable for producing a coating for a plate, for example a cover plate, such as a so-called cooking plate as a cover for a cooking appliance, which, in the region of the plate in which the coating is arranged, has a low light transmittance with, at the same time, high IR transparency, in particular in the range between 780 nm and 2500 nm, and additionally a high L* value.

[0133] Furthermore, the coating here contains less than 1% by weight of graphite. It is important to note that the graphite content of such coatings cannot usually be reduced arbitrarily. For example, it would be possible to achieve a particularly light color impression of a coating by not adding any graphite to the coating. However, graphite not only acts as a color-imparting component of such a coating, but also improves the adhesion and scratch resistance of the coating. Furthermore, graphite also acts as a lubricant and is distributed very well into the gaps that arise in the coating between the stacked platelet-shaped pigment particles. It therefore also increases the impermeability of the coating. It is therefore advantageous if the coating has at least a certain graphite content. However, this is limited.

[0134] In Fig. 2 and Fig.3 are the transmission spectra of the plate according to the example for the wavelength range from 850 nm to 1000 nm ( Fig. 2) and from 1000 nm to 2000 nm ( Fig. 3). The total transmittance, i.e., the transmittance PvK, is shown in each case. As already explained above, the total transmittance includes the portions of directly transmitted electromagnetic radiation and the portions of scattered transmitted radiation. Thus, the difference between the measured transmittance values ​​from "PvK" measurements and "PiP" measurements corresponds to the scattered portion of the transmittance.

[0135] The total transmission, i.e. the spectral transmittance PvK, is therefore always more than 40% in the wavelength range between 850 nm and 1000 nm for the plate according to the example, as can be seen from the transmission spectrum 1 of the Fig. 2, in the wavelength range between 1000 nm and 2000 nm it is always more than 50%, see Fig. 3, transmission spectrum 1. The values ​​of the spectral transmittance PvK for the comparison example, which is designated with 2, are each significantly lower.

[0136] The proportion of scattered light or scattered electromagnetic radiation at a wavelength is calculated, as explained above, from the difference between the “PvK” and “PiP” measured values.

[0137] According to a further preferred embodiment of the plate, the spectral transmittance PvK of the plate for electromagnetic radiation in the region of the glass or glass-ceramic substrate in which the coating is arranged is at least 10%, preferably at least 20% and particularly preferably at least 30% and at most 50% in the wavelength range between 3.25 µm and 4.25 µm at at least one wavelength.

[0138] Fig.Figure 5 shows spectra of the spectral transmittance PiP in the spectral range from 250 nm to 4750 nm. Transmission spectrum 3 shows the spectral transmittance PiP for Example 1 as an embodiment. At 3750 nm, the spectral transmittance PiP is 26%. The spectral transmittance PvK cannot be lower than the spectral transmittance PiP and therefore lies between 26% and the value of the uncoated glass-ceramic, indicated here with the transmission spectrum 5. The values ​​​​in each case refer to a thickness of the substrate under consideration of 4 mm. For the uncoated glass-ceramic, the spectral transmittance PiP is approximately equal to the spectral transmittance PvK due to the lower scattering.

[0139] Comparing transmission spectra 3 and 5, it can be seen that the coating reduces the transmission at 3.25 µm by a factor of 2.

[0140] 6 denotes the transmission spectrum of an uncoated glass with a thickness of 4 mm and a composition corresponding to the glass Borofloat 33. At a wavelength of 3.25 µm, the glass substrate has a spectral transmittance PiP of 30%, which should be reduced to approximately 15% with a coating according to Example 1.

[0141] A comparison of the scattering of a plate comprising a glass or glass-ceramic substrate with a top side and a bottom side and a coating according to the present disclosure with a comparative example Fig. 6 and Fig. 7.

[0142] In Fig.6 plots the scattering in the range from 300 nm to 900 nm, thus encompassing the visible light range. Curve 7 denotes the scattering in the at least one region of at least one side of the glass-ceramic substrate in which the coating is arranged, for a plate according to Example 1 of the present disclosure, and curve 8 denotes the scattering for a plate according to the comparative example. The values ​​are each based on a substrate thickness of 4 mm.

[0143] The scattering at a specific wavelength was determined as the difference between the spectral transmittance PvK and the spectral transmittance PiP. With reference to Fig.4, curve 5 is the difference between curve 1 and curve 3; curve 8 is the difference between curve 2 and curve 4. It can be seen that the scatter at 400 nm for the plate according to the example is less than 15% and at 800 nm less than 35%.

[0144] Fig. Figure 7 shows scattering spectra 7 and 8 again, but here determined in the range from 300 to 2500 nm.

[0145] Additionally, it has been shown that the color coordinate of a panel according to the invention exhibits high thermal stability. When exposed to a temperature of 400 °C for 75 hours, the color coordinate of Example 1 changed by only ΔE < 1.5 compared to the color coordinate given in Table 1.

[0146] Fig. Figure 8 shows a schematic and not to scale representation of a plate 10 according to an embodiment.

[0147] The plate 10 comprises a glass or glass-ceramic substrate 100 with a top side 101 and a bottom side 102, as well as a coating 20, wherein the glass or glass-ceramic is transparent and uncolored. The coating 20 is arranged in at least one region 30 of the glass or glass-ceramic substrate 100 on at least one side of the glass or glass-ceramic substrate 100 and comprises a pigment comprising pigment particles. The plate 10 has, in the at least one region 30 of the glass or glass ceramic substrate 100, an L* value of at least 70, preferably at least 75, measured against a white tile through the glass or glass ceramic substrate 100, a light transmittance between at least 0.1% and 8% and a spectral transmittance PvK for electromagnetic radiation of at least 55% at 1600 nm wavelength, in each case based on a thickness of the glass or glass ceramic substrate 100 of 4 mm.

[0148] Furthermore, the plate 10 here comprises a further coating 21. The further coating 21 is arranged in at least one region 31 of the glass or glass-ceramic substrate 100 on at least one side of the glass or glass-ceramic substrate 100, preferably on the same side as the coating 20. The further coating 21 comprises a pigment comprising pigment particles. In the at least one region 31 of the glass or glass-ceramic substrate 100 in which the further coating 21 is arranged, the plate 10 has a light transmittance of between at least 0.001% and at most 2%, preferably between at least 0.01% and at most 1%, wherein the further coating 21 has a recess 41, which preferably forms a window. The coating 20 is at least partially arranged in the region of the recess 41 of the further coating 21.It is possible and may be preferred for the coating 20 to fill the entire region 41, as schematically illustrated here. Furthermore, the coating 20 may also overlap completely or partially with the coating 21, for example in an edge region. It is also possible for not the entire region of the recess 41 to be covered with the coating 20. The color difference ΔE of the color locations of the coating 20 and the further coating 21 in the CIELAB color space, measured through the glass or glass-ceramic substrate 100, is in the range from more than 0 to 5, preferably in the range from more than 0 to 4, particularly preferably in the range from more than 0 to 2, and in particular in the range from more than 0 to 1.

[0149] Here, the coating 20 is arranged in at least one region of the glass or glass-ceramic substrate 100 on the underside 102 of the glass or glass-ceramic substrate 100. The plate 10 further comprises a functional coating 22, which is not in direct contact with one of the main surfaces 101, 102 of the glass or glass-ceramic substrate 100. The functional coating 22 preferably comprises a pigment comprising pigment particles. The functional coating is applied at least in a partial region to the coating 20 and / or the further coating 21, here to the further coating 21. The light transmittance of the plate 10 in the region 32 in which the functional coating 22 is arranged is between a minimum of 10 -5% and at most 0.5%, preferably at most 0.1%. The functional coating 22 has a recess 42 which forms a window, wherein the coating 20 is preferably arranged at least partially or over its entire area in the region of the recess 42. The functional coating 42, measured on the surface of the functional coating 42, preferably has an L* value of more than 40, preferably more than 50, and particularly preferably more than 60. Here, the recess 42 in the functional coating 22 and the recess 41 in the further coating 21 overlap one another at least partially.

[0150] Preferably, the functional coating 21 is a masking and / or a sealing layer. List of reference symbols 1 Curve of the spectral transmittance PvK of Example 1 2 Curve of the spectral transmittance PvK of the comparison example 3 Curve of the spectral transmittance PiP of Example 1 4 Curve of the spectral transmittance PiP of the comparison example 5 Curve of the spectral transmittance PiP of an uncoated, transparent, uncolored glass-ceramic 6 Curve of the spectral transmittance PiP of an uncoated, transparent, uncolored glass 7 Curve of the scatter of Example 1 8 Curve of the dispersion of the comparison example 10 plates 100 glass or glass-ceramic substrate 101 Top side of the glass or glass-ceramic substrate 102 Underside of the glass or glass-ceramic substrate 20 Coating 21 additional coating 22 functional coating 30 Area of ​​the plate in which the coating 20 is arranged 31 Area of ​​the plate in which the further coating 21 is arranged 32 Area of ​​the plate in which the functional coating 22 is arranged 41 Recess in the further coating 21 42 Recess in the functional coating 22

Claims

[1] Plate (10) comprising a glass or glass-ceramic substrate (100) with a top side (101) and a bottom side (102) and a coating (20), wherein the glass or glass-ceramic is transparent and uncolored, wherein the coating (20) is arranged in at least one region (30) of the glass or glass-ceramic substrate (100) on at least one side (101, 102) of the glass or glass-ceramic substrate (100), wherein the coating (20) comprises a pigment comprising pigment particles, wherein the plate (10) in the at least one region (30) of the glass or glass-ceramic substrate (100) in which the coating (20) is arranged, an L* value of at least 70, measured against a white tile through the glass or glass-ceramic substrate (100), a light transmittance between at least 0.1% and 8% and a spectral transmittance PvK for electromagnetic radiation of at least 55% at 1600 nm wavelength each based on a thickness of the glass or glass-ceramic substrate (100) of 4 mm, has. [2] Plate (10) according to claim 1, wherein the pigment particles comprise a pigment substrate and a pigment coating, wherein the pigment substrate comprises an oxidic material [3] Plate (10) according to claim 2, wherein the pigment particles have a maximum lateral dimension between at least 5 µm and at most 25 µm. [4] Plate (10) according to one of claims 1 to 3, wherein the pigment particles are free of Fe2O3 except for unavoidable traces. [5] Plate (10) according to one of claims 1 to 4, wherein the coating (20) comprises at most 1 wt.% graphite. [6] Plate (10) according to one of claims 1 to 5, wherein the light transmittance of the plate (10) in the region (30) of the glass or glass-ceramic substrate (100) in which the coating (20) is arranged is at least 0.5%. [7] Plate (10) according to one of claims 1 to 6, wherein the spectral transmittance PvK of the plate (10) in the region (30) of the glass or glass-ceramic substrate (100) in which the coating (20) is arranged is at least 30% at each wavelength in the wavelength range between 1 µm and 2 µm. [8] Plate (10) according to one of claims 1 to 7, wherein the spectral transmittance PvK of the plate (10) for electromagnetic radiation in the region (30) of the glass or glass-ceramic substrate (100) in which the coating (20) is arranged is at least 30% at at least one wavelength in the wavelength range between 850 nm and 1000 nm. [9] Plate (10) according to one of claims 1 to 8, wherein the light scattering of the plate (10) in the region (30) of the glass or glass-ceramic substrate (100) in which the coating (30) is arranged is less than 15% at 400 nm and / or the scattering of the plate (10) for electromagnetic radiation at 800 nm is less than 35%. [10] Plate (10) according to one of claims 1 to 9, wherein the spectral transmittance PvK of the plate (10) for electromagnetic radiation in the region (30) of the glass or glass-ceramic substrate (100) in which the coating (20) is arranged is at least 10% in the wavelength range between 3.25 µm and 4.25 µm at at least one wavelength. [11] Plate (10) according to one of claims 1 to 10, wherein the plate (10) comprises a further coating (21), wherein the further coating (21) is arranged in at least one region (31) of the glass or glass-ceramic substrate (100) on at least one side (101, 102) of the glass or glass-ceramic substrate (100), wherein the further coating (21) comprises a pigment comprising pigment particles, wherein the plate (10) in the at least one region (31) of the glass or glass-ceramic substrate (100) in which the further coating (21) is arranged has a light transmittance of between at least 0.001% and at most 2%, preferably between at least 0.01% and at most 1%, wherein the further coating (21) has a recess (41), wherein the coating (20) is arranged at least partially or over the entire surface at least in the region of the recess (41) of the further coating (21), wherein the color difference ΔE of the color locations of the coating (20) and the further coating (21) in the CIELAB color space, measured through the glass or glass-ceramic substrate (100), is in the range from more than 0 to 5. [12] Plate (10) according to one of claims 1 to 11, wherein the coating (20) is arranged in at least one region (300) of the glass or glass-ceramic substrate (100) on the underside (102) of the glass or glass-ceramic substrate (100), wherein the plate (10) comprises a functional coating (22) which is not in direct contact with a main surface (101, 102) of the glass or glass-ceramic substrate (100), wherein the functional coating (22) is applied to the coating (20) and / or the further coating (21) at least in a partial area, wherein the light transmittance of the plate (10) in the region (32) in which the functional coating (22) is arranged is between at least 10 -5% and at most 0.5%, wherein the functional coating (22) has a recess (42) which forms a window. [13] Plate (10) according to claim 12, wherein the functional coating (22) is a masking and / or a sealing layer. [14] Cooking appliance comprising a plate (10) according to any one of claims 1 to 13. [15] Use of a plate (10) according to one of claims 1 to 13 as a cover or separating plate, or as a cooking plate in a cooking appliance, or as a fireplace viewing window, or as a radiator cover or as a housing component of electronic devices.

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