Glass or glass ceramic plate including at least one coating film arranged on one surface and manufacturing method thereof

Abstract

To provide a coated glass or a glass ceramic plate having scratch resistance and having very excellent scratch resistance and very excellent oil resistance as a single layer, and usable as a cover plate of cooking wares and a manufacturing method thereof.SOLUTION: In a glass or a glass ceramic plate including a coating film arranged on at least one surface of a glass or a glass-ceramic substrate, the coating film has a thickness of at least 10 μm, the coating film has, in a region of the glass or the glass ceramic plate, where only the coating film is arranged on the glass or the glass-ceramic substrate, a scratch resistance in an examination according to DIN-ISO 1518-1 of over 7 N, and an oil resistance obtained as a chromaticity change ΔE represented by a specific formula measured via the glass or the glass-ceramic substrate of under 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention generally relates to a coated glass or glass-ceramic plate that can be used, for example, as a cover plate for cooking appliances. In particular, the present invention relates to a glass or glass-ceramic plate comprising a coating disposed on at least one surface of a glass or glass-ceramic substrate, and a method for manufacturing the same. The coating comprises an organosilicon matrix and a pigment, has scratch resistance, and has very excellent scratch resistance and very excellent oil resistance as a single layer.

Background Art

[0002] Coated glass or glass-ceramic plates have been used for many years as cover plates for cooking appliances (for example, known as "cooktops" of "ranges"). In recent years, cover plates containing glass or glass-ceramic, comprising a transparent glass or glass-ceramic material and a coating applied to one side of the corresponding glass or glass-ceramic substrate to prevent the material from being seen through, have been developed. Such coatings face away from viewers and users when the cooking appliance is installed and are generally also referred to as bottom coats or back coats.

[0003] These bottom or back coats are exposed to various requirements during assembly and operation, but since they are disposed on the back or bottom surface of the plate, they also have a decisive influence on the impact resistance, which is important during operation and use. Here, the impact resistance refers to the strength of the plate to withstand mechanical loads "from above" or "from the front", and when the coated plate is used as a cover plate for a range, it can be visualized by sometimes carelessly placing cooking utensils downwards.

[0004] Particularly in the case of a low-expansion substrate, a so-called "thermal mismatch", i.e., a difference in thermal expansion, will necessarily occur between the substrate and the coating film applied to this substrate. Therefore, in the case of a back coating, particularly a coating film with excellent adhesion and / or abrasion resistance, cracks may be induced in the substrate (e.g., due to a high baking temperature and the mismatch that occurs when the coated substrate is cooled to room temperature), which can reduce the mechanical durability of the substrate. Thus, tensile stresses acting on the substrate, such as those caused by an object placed on a plate, e.g., a load from above by a cooking utensil, can easily lead to the malfunction of the substrate due to fracture. For this reason, particularly when a substrate with relatively low ductility, such as a specific glass-ceramic or glass, is used, the use of a glass-based coating film as a "back coating" or "bottom coating" that is particularly excellent in adhesion and abrasion resistance and also satisfies other requirements regarding sealing and cleanability well by itself has not been established.

[0005] Therefore, particularly as the back or bottom coating, a coating film with lower adhesion than conventional glass-based coating films is used. For example, silicone-based coating films and silicon-based sol-gel binders have been proposed. In the case of such coating films, since a melting reaction zone as in the case of conventional glass-based coating films is not formed, for this reason alone, the risk of crack formation is relatively low. However, this has the drawback that the adhesion of this layer also becomes low. In order to ensure the strength of a plate covered with such a coating film, it is often further advantageous for the coating film to be particularly porous up to the substrate. However, the lower surface or back surface of the cover plate comes into contact with fluid media very often, such as adhesive residues, water vapor, or even oil, or in the case of a cover plate used in a stove operated by a gas burner, spilled food reaching the lower surface of the cover plate through the holes of the gas burner. Therefore, this porosity is particularly disadvantageous. Another drawback of the porous layer is usually its low abrasion resistance. The corresponding coating film is described, for example, in German Patent Application Publication No. 102008031428.

[0006] For this reason, often another coating film is arranged on the first layer that is actually colored and visible through the substrate by the user, and this is also called a "sealant". This second coating film often has a different composition from the first coating film and may require different baking conditions. Also, the first coating film and the second coating film may have different color densities. This is particularly disadvantageous when the first coating film has a very light color and the second coating film has a very dark color. In this case, the first coating film must be applied particularly thickly, otherwise, the second coating film will be slightly visible through the first coating film, and the color density will change. The corresponding coating film is described, for example, in German Patent Application Publication No. 102008031426.

[0007] Furthermore, the combination of the colored layer and the sealant layer means an additional application process and heat treatment process, and thus is disadvantageous both from an economic perspective and from the perspective of the product's CO2 balance.

[0008] For example, European Patent No. 1730085 describes a plate made of glass or glass ceramic and having a colored coating film in at least one region of at least one surface, wherein the coating film contains at least one polysiloxane resin that substantially does not contain a carbon-free material, and the coating film has a filler content of 10 to 60% by volume. The drawback is that the coating film described in this patent document substantially does not contain carbon, because in such a manner, it is not possible to obtain a coating film having sufficient sealing properties, particularly with respect to the durability against the passage of oil.

[0009] International Publication No. 2005 / 092810 describes a method for enhancing the strength of a glass or glass ceramic plate. A colored coating film having high durability against the passage of oil is not described.

[0010] JP-T-2011 / 216457 discloses a plate including a glass or glass-ceramic substrate, the plate having a bottom coat including different coating films. In particular, the color-forming coating film 3 has a different configuration from the heat-resistant resin layer 4, and further, another resin layer 5 for further improving the performance of the first resin layer 4 may be further provided. Therefore, the described plate has a very complex layer structure where processes such as sputtering and even glass-based coating films may be used.

[0011] JP-B-6231066 describes a manufactured article in which a coating film containing a silicone resin having an alkyl chain that may be branched is applied to a glass or glass-ceramic substrate. This method is disadvantageous because these organic components require baking at a fairly high temperature, for example, around 350 °C. However, with such a method, a coating film having both sealing properties and scratch resistance cannot be produced because a porous layer is formed by the combustion of the organic components.

[0012] Also, JP-A-206024 describes a coated glass plate including two different configuration coating films, a decorative coating film and a light-shielding coating film. The decorative coating film further contains another metal oxide such as MnO and / or CoO in addition to SiO2 as an essential component.

[0013] JP-T-2019 / 519458 discloses a coating film on a glass or glass-ceramic plate including a silicone binder and a nano pigment. The scratch resistance and sealing properties of the coating film are not mentioned.

[0014] EP-A-3511631 describes a multilayer structure including a first decorative layer and a second heat-resistant resin layer. This layer contains pigments with a very small particle size. The resin layer may be directly applied to the substrate. The oil resistance of the coating film is not mentioned.

[0015] European Patent Application Publication No. 3222595 describes a stove device including a layer element that is partially translucent. Oil tightness and scratch resistance are not mentioned.

[0016] International Publication No. 2020 / 122069 describes a cooktop including a heat-resistant resin layer. This contains in particular flaky inorganic fillers containing aluminum oxide. Again, oil resistance is not mentioned.

[0017] In other words, existing glass or glass-ceramic plates with a coated back surface are demanding and costly to manufacture. Therefore, there is a need for a glass or glass-ceramic plate that at least partially alleviates the disadvantages of the prior art described above. Similarly, a manufacturing method thereof is also needed.

[0018] Problem of the Invention The problem of the present invention lies in providing a glass or glass-ceramic plate including at least one coating film disposed on at least one surface, which at least partially alleviates the disadvantages of the prior art, and a manufacturing method thereof.

[0019] Summary of the Invention This problem is solved by the subject matter of the independent claims. Preferred and special embodiments are the subject matter of the dependent claims as well as the present specification and drawings of the present disclosure.

[0020] Accordingly, the present disclosure relates to a glass or glass-ceramic plate comprising a glass or glass-ceramic substrate and a coating film comprising an organosilicon matrix and a pigment disposed on at least one surface of the glass or glass-ceramic substrate. The coating film has a thickness of at least 10 μm, preferably at most 80 μm. The coating film has a scratch resistance of more than 7 N, preferably at most 30 N, determined in a test according to DIN ISO 1518-1, in a region of the glass or glass-ceramic plate where only the coating film is disposed on the glass or glass-ceramic substrate, and an oil resistance of less than 1, preferably less than 0.5, particularly preferably less than 0.3, very particularly preferably less than 0.2, most preferably less than 0.1, determined as a chromaticity change ΔE when measured through the glass or glass-ceramic substrate, where the chromaticity change ΔE is L * a * b * in the color system by the following formula:

Equation

[0021] Here, chromaticity 1 refers to the chromaticity of the glass or glass-ceramic plate measured through the glass or glass-ceramic substrate before loading with the colored oil, and chromaticity 2 refers to the chromaticity after loading with the colored oil.

[0022] The test is preferably carried out as follows: The coloring of the oil is preferably carried out with a blue dye such as sold under the trade name Orasol Blue 855. This is a dye generally consisting of a copper-phthalocyanine complex and is also known as C.I. Solvent Blue 70 (CAS number 12237-24-0). For this purpose, first 0.5 g of the powdered dye is dissolved in 10 ml of isopropanol. Next, a commercially available oil, such as sunflower oil, is poured into this solution to make 50 ml.

[0023] The composition ranges of commercially available sunflower oils suitable for the test are in the following list (see also de.wikipedia.org / wiki / Sonnenblumenoel from May 4, 2022):

Table 1

[0024] Next, test specimens are prepared. These are test pieces with a minimum size of 80×80 mm made of coated glass or glass-ceramic plates. 2 Advantageously, the test pieces contain only the substrate and the coating film to be tested. The chromaticity of the coating film is measured before loading, but through the substrate. Next, 2 ml of the edible oil colored as described above, advantageously commercially available sunflower oil, is applied to the coating film, and the sample to which the colored oil has been applied is heat-treated in an oven at 150°C for 3 hours. Then, the chromaticity of the coating film is measured again through the substrate. This measurement of chromaticity is performed using a color difference meter for each of the CIE-L * a * b * color space system. Next, the chromaticity change ΔE is determined from the measured values before and after loading. It is also possible to measure the chromaticity at untreated and oil-treated locations of the sample and determine the chromaticity change therefrom, which may also be preferred for larger samples. This is possible because the heat treatment temperature of 150°C is too low to cause a chromaticity change in the coating film itself quickly enough. Therefore, the chromaticity of the untreated location coincides with the chromaticity before treatment within the measurement accuracy range. To eliminate the possibility of errors and artifacts, it is also possible to heat-treat a reference sample together, thereby avoiding artifacts in case of foreign matter contamination of the sample in the oven itself, for example.

[0025] Generally, it may be advantageous to proceed as follows: Place a ring, preferably made of or containing commercially available stainless steel, preferably with an inner diameter of 40 mm, on the surface of the plate / substrate on which the coating film is disposed. The outer diameter may be, for example, 57 mm, and it should be understood that the exact dimensions of the outer diameter are merely illustrative. This ring functions particularly as a boundary to prevent the disorderly leakage of oil. Next, add 2 ml of colored oil to this ring, preferably by dropping using a pipette. Then, cover the ring, for example, with a watch glass to prevent the rapid evaporation of the oil. Next, place the sample to which the colored oil has been applied in a laboratory oven and then heat it to 150 °C. Hold this temperature of 150 °C for 3 hours. After the sample has cooled, remove the ring and the cover, and remove the residual oil still present on the surface of the coating film, for example, with a cellulose cloth.

[0026] Preferably, the oil after heat treatment is still liquid and does not show viscosity. If it is viscous, it is presumed that the temperature of the oven is too high.

[0027] Next, turn the sample over and evaluate it from the substrate side. First, evaluate it visually. Further, CIEL * a * b * Measure the chromaticity using a color difference meter in the CIELab color system. For this purpose, measure the chromaticity at the untreated part and the treated part of the test piece, and calculate the chromaticity change ΔE according to the above sample. Further, preferably, also record an untreated reference sample together.

[0028] Preferably, use a CM700d type device, a spectrophotometer manufactured by Konica Minolta, to measure the chromaticity at a light type D65 and an observation angle of 10°. The measurement aperture MAV and the measurement setting SCI can be used. Since the test piece has high opacity, the measurement is independent of the background, that is, it is not important whether the measurement is performed against a black calibration plate or a white calibration plate.

[0029] Within the scope of the present disclosure, it is understood that a plate is a shaped body whose thickness is at least one order of magnitude smaller than its length and width. Further, a glass or glass-ceramic plate within the scope of the present disclosure is understood to be a manufactured article comprising a glass or glass-ceramic substrate, where the glass or glass-ceramic substrate itself is plate-shaped. Unlike the glass or glass-ceramic substrate, the glass or glass-ceramic plate further comprises at least one coating film and can thus also be understood as a processed substrate. The three-dimensional dimensions and surfaces of the glass or glass-ceramic substrate and those of the glass or glass-ceramic plate are substantially identical to each other, but it should be noted here that, strictly speaking, the thickness of the glass or glass-ceramic plate is greater than the thickness of the (uncoated) glass or glass-ceramic substrate by the thickness of the coating film. However, this is negligible within the measurement accuracy for the normal mm-range thicknesses of the glass or glass-ceramic plates / substrates considered herein.

[0030] The configuration of a glass or glass-ceramic plate as described above has many advantages.

[0031] The coating film is herein configured as a coating film containing an organosilicon matrix and a pigment, and thus as a concealing or at least partially concealing coating film. A concealing or at least partially concealing coating film (or layer) is understood within the scope of the present disclosure to be a coating film that at least reduces the transmission of light. This can be attributed, on the one hand, to the coating film containing a pigment, i.e., a colorant, preferably a temperature-stable and / or ceramic colorant, which reduces the transmission of light by absorption and / or scattering. On the other hand, since the coating film has a thickness of at least 10 μm, the concealing effect of the coating film can also be attributed to its thickness. It is understood that within the scope of the present disclosure, the colorants include not only colored pigments but also effect pigments, and the effect pigments do not necessarily exhibit color by themselves and may be formed, for example, as pure silver metallic pigments (corresponding to, for example, so-called "true pearl metallic pigments"). Generally, these effect pigments that do not necessarily exhibit color by absorption themselves are included in the general term "colorant" within the scope of the present disclosure.

[0032] Thus, even when using pigments or coating films that do not inherently have a particularly strong concealing effect, a concealing effect can be achieved because they are, for example, coating films based on transparent flakes as effect pigments (such as true pearl metallic pigments, for example, those commercially available under the trade name "Iriodin") or coating films containing a large amount of such pigments. Here, the high layer thickness of at least 10 μm and the pigment contained in the coating film advantageously interact with each other, ensuring a sufficient concealing effect of the coating film.

[0033] Pearlescent pigments are generally understood to be mica-based effect pigments. In particular, mica may be present in flake form and may be coated, whereupon the coating itself may be a non-absorbent coating, for example a coating consisting of or containing TiO2. In this way, for example, a dull silver sheen can be achieved. It is also possible to cause an interference effect by having such pearlescent pigments included in a plurality of coatings. In this case, for example, a specific color impression can be realized by reflection. It is also possible to use a coating material that exhibits a certain inherent color, such as Fe2O3. In this case, the resulting pearlescent pigment has a light color tone but is still not a concealing absorbent pigment. For example, pearlescent pigments having yellow or gold hues are known. Other color hues, such as purple, are also possible in principle.

[0034] Pearlescent pigments are also referred to as mica pigments within the scope of the present disclosure.

[0035] The coating contains an organosilicon matrix in addition to at least one pigment. The organosilicon matrix is understood to be a coating matrix obtained from an organosilicon precursor material, which may also be referred to as a "binder". Known organosilicon precursor materials include, for example, TEOS (tetraethyl orthosilicate), TMOS (tetramethyl orthosilicate) or their organically modified derivatives (m-TEOS, methyltriethyl orthosilicate, DMDEOS, dimethyldiethyl orthosilicate, phenyltriethyl orthosilicate, etc.). Silicones and polysiloxanes are also considered possible components of the organosilicon binder within the scope of the present disclosure. Here, in particular, the organosilicon binder according to the present disclosure can in particular contain a plurality of precursor materials. In particular, it is possible for the binder to contain a sol-gel component and a polysilsesquioxane component or a silicone resin component.

[0036] The coating film is configured to have scratch resistance by itself, that is, it has a scratch resistance of more than 7 N in a test conforming to DIN-ISO 1518-1 as a single layer on a glass or glass-ceramic substrate.

[0037] Generally, within the scope of the present disclosure, the material layer applied to the substrate by the coating step is referred to as a coating film or layer.

[0038] A single layer is understood to be a coating film or layer of the same composition within the scope of the present disclosure. Here, the coating film can be applied in a plurality of coating steps or in a single coating step. For example, a single layer within the scope of the present disclosure can also be obtained by two or more consecutive coating processes, such as double printing. This can be advantageous, for example, in the case of a coating film with a very low hiding power where only a low layer thickness can be obtained in a single coating process, such as screen printing. Such a coating film can also be interpreted as containing two partial layers of the same composition. In this case, advantageously, at least one or more additional coating steps can be carried out after the first coating step, such as the first printing, so that a sufficiently thick coating film is obtained as a whole. Here, it is also possible to carry out intermediate steps, such as heat fixing of the preceding coating film, after the coating step, but this is not absolutely necessary.

[0039] Unlike a single layer, within the scope of the present disclosure, there are a plurality of layers (or coating films) containing material layers having different compositions, for example, with respect to the type of pigment or binder used. The binder may also be referred to as a binder phase or matrix within the scope of the present disclosure, which is particularly applicable when referring to a cured coating film rather than a paste.

[0040] The coating film of the present invention on a glass or glass-ceramic plate also exhibits very excellent durability in the oil test.

[0041] Within the scope of the present disclosure, the oil test is understood to be a test for examining the permeability of a coating film to oil. The visibility of a fluid that penetrates into the coating film and then through the coated substrate is a difficult problem, particularly in the case of a coating film containing, for example, effect pigments. This is because, depending on the detailed composition of the coating film, particularly when the coating film contains effect pigments, it has been found that the penetration of the fluid can only be visually recognized at certain angles, partially. This is different from the case of a coating film formed as a pure "body coating material", that is, a coating film that does not contain or contains only very little effect pigment. In this case, for example, when water penetrates into the pores of the coating film, it can be very easily visually recognized because the pores become filled and the color appears darker.

[0042] Therefore, the inventors have developed the above-described test method for testing the sealing property of a coating film, and in this method, oil mixed with a dye as described above is used. If the sealing property of the coating film is not sufficient, the oil, together with the added dye, penetrates into the pores of the coating film and can be perceived visually on the "opposite side", that is, on the side of the coating film adjacent to the substrate, in the form of a color change implemented by measuring the chromaticity before and after the loading of the colored oil. Here, the chromaticity change ΔE is 2 or less, preferably even smaller, and particularly preferably imperceptible, in the coating film according to the embodiment. Thus, the coating film is considered to have sufficient sealing property.

[0043] Such an embodiment in which the single layer has both scratch resistance and non - permeability has not been known in the prior art. Conventionally, it has been considered that at least two coating films with different compositions depending on, for example, the content of pigments and binders and the difference in baking conditions are required. The first coating film directly disposed on the substrate is porous, especially by baking at high temperatures, and the second coating film disposed on the first coating film is sealing. In this case, in particular, baking by heat at a high temperature exceeding 300 °C or 350 °C is omitted. Thus, such known glass or glass - ceramic plates of the prior art are so - called two - layer systems, including first and second coating films that must be adapted to each other with respect to their composition, baking conditions, and, if necessary, the resulting color impression. Only in this way was it possible to guarantee sufficient scratch resistance, sufficient sealing, and sufficient mechanical strength of the glass or glass - ceramic plate under the use conditions.

[0044] The inventors presume that the fact that the single layer of the present disclosure has scratch resistance and sealing properties at the same time is due to the special configuration of the binder used. Therefore, the coating agent used for manufacturing the glass or glass - ceramic plate according to the embodiment includes a binder containing at least two organosilicon precursors or precursors. One organosilicon precursor is a silicone resin, especially a commercially available silicone resin, and the other organosilicon precursor is a sol - gel hydrolysis product. In addition to the binder, the coating agent further includes at least one pigment.

[0045] This configuration is highly advantageous. This is because by using the sol-gel hydrolysis product of an organosilicon compound or a mixture of organosilicon compounds, it is very easy to adjust the advantageous properties of the pigment coating film that is not too strong but has sufficient adhesion strength. However, as already shown, such a coating film is not suitable for forming a single layer on a glass or glass-ceramic substrate for use as a back or bottom coat. This is because these layers are over-baked and thus too porous, so they do not exhibit self-sealing properties (i.e., the very excellent oil resistance according to the present disclosure), or they are only dried without baking, so their temperature stability is insufficient. This is because when the cooking appliance equipped with this is operated later, i.e., under a heat load, baking occurs, and thus the sealing property of the coating film deteriorates over time. Also, the coating film without baking does not have excellent adhesion strength and therefore does not have sufficient scratch resistance.

[0046] However, now it has surprisingly become very easily possible to provide a glass or glass-ceramic plate including a coating film having scratch resistance and sealing properties even when implemented as a single layer.

[0047] According to one embodiment of the glass or glass-ceramic plate, in the glass or glass-ceramic plate, the flexural strength measured by the double-ring method in accordance with EN 1288-5 is at least 140 MPa (when determined as the arithmetic mean value over the entire sample of at least two samples), preferably at most 250 MPa. Thereby, the mechanical stability of the glass or glass-ceramic plate is advantageously supported. According to one embodiment, the glass or glass-ceramic plate has a 5% fractile of flexural strength of at least 100 MPa, and preferably at least 18 samples are used to determine the 5% fractile.

[0048] According to one embodiment, in a glass or glass-ceramic plate, the impact resistance measured by a ball drop test in accordance with UL 858 is at least 45 cm, preferably at least 60 cm, preferably at least 70 cm, preferably at least 80 cm, particularly preferably at least 90 cm, when determined as the arithmetic mean value over the entire sample of at least two samples, where the impact resistance is determined for a coating disposed on the lower surface of the glass or glass-ceramic plate. Further, according to one embodiment, in a glass or glass-ceramic plate, the impact resistance measured by a ball drop test in accordance with UL 858 is at least 35 cm, preferably at least 40 cm, particularly preferably at least 45 cm or more at the 5% fractile. Also, for the measurement of the impact resistance, the coating is disposed on the lower surface of the sample, i.e., a load is applied to the upper surface of the sample or the glass or glass-ceramic plate by the impact (or the ball drop in the test), and the coating according to the embodiment is disposed on the surface of the sample / glass or glass-ceramic plate on the opposite side.

[0049] As already explained, the lower surface of the glass or glass-ceramic plate is understood to be the surface of the plate that faces away from the operator / viewer / user during the operation and use of the plate. For example, it is possible and even preferable to provide protrusions on the lower surface, because by doing so, particularly high strength, and particularly impact resistance of the plate can be set. However, it may be provided that both surfaces of the plate are smoothed, because this makes it easier, in particular, to incorporate display elements below the plate as components of the control elements of the device equipped with the plate.

[0050] According to a further embodiment of the glass or glass-ceramic plate, the glass or glass-ceramic plate has a light transmittance of less than 0.08%, preferably less than 0.04%, particularly preferably less than 0.02% measured in accordance with DIN 5036 Part 1 in the region where the coating film is disposed. The light transmittance data preferably relates to the region where only the coating film according to the embodiment is disposed on the glass or glass-ceramic substrate.

[0051] Thus, in other words, the coating film is formed to be substantially opaque or concealing.

[0052] This can be advantageously assisted by an appropriate ratio of pigment to binder in the coating film. According to an embodiment of the glass or glass-ceramic plate, the ratio of pigment to binder in the coating film is 0.8 to 1.3, preferably 1:1 to 1:2.5, particularly preferably 1:1.3 to 1:2, based on the weight ratio respectively. In this way, a good concealing effect of the coating film is advantageously ensured. Furthermore, in this way, it is also possible to configure the glass or glass-ceramic plate so as to obtain both high strength and sufficient adhesion strength of the coating film.

[0053] When referring to the ratio of "pigment to binder" within the scope of the present disclosure, the total amount of pigments contained in the coating film is always intended herein. Here, the pigment is understood to be a colored body containing particles, particularly an inorganic colored body, preferably a ceramic, i.e., an inorganic non-metallic colored body. For example, in order to adjust a specific color and / or one of the other properties of the coating film, the coating film can contain, and may be necessary to contain, a plurality of pigments, for example, pigments having different colors or color shades. In this case, the numerical value of the pigment-binder ratio is with respect to the sum of the pigments contained in the coating film, i.e., the total pigment ratio.

[0054] According to a further embodiment, the coating film contains an effect pigment, and the ratio of the effect pigment to the total pigment ratio is 50 wt% to 100 wt%, preferably 70 wt% to 100 wt%, particularly preferably 88 wt% to 98 wt%.

[0055] The construction of a coating film containing at least one effect pigment is usually carried out to adjust a specific appearance ("metallic coating"). However, it has been found that effect pigments can also perform other functions within the coating film. This is because the generally flaky formation of many effect pigments, such as so-called nacreous pigments, can further assist in the formation of advantageous properties of the coating film, such as high abrasion resistance. Therefore, advantageously, the proportion of the effect pigment relative to the total pigment proportion may be provided to be not too low, for example, at least 50% by weight, advantageously at least 70% by weight, particularly preferably at least 88% by weight.

[0056] Generally, it is possible for a coating film as a coloring body - or in the special case of an effect pigment, a coating film as an "effect body" - to contain only one effect pigment, and thus the proportion of the effect pigment relative to the total pigment proportion can also be 100% by weight. However, there may be cases where it is advantageous and preferable for its content to be less, for example, only 98% by weight. This is particularly the case when the effect pigment itself does not exhibit color, for example, in the case of a pure "silver-white" nacreous pigment. In this case, that is, setting a sufficiently high optical density of the coating film - in other words, making the coating film "opaque" - can be achieved simply by making the layer thickness very thick. Therefore, in order to enhance the hiding effect of the coating film, it may be advantageous to further add at least one additional pigment that exhibits color by absorption and / or scattering or, if necessary, a plurality of other pigments. Also, in order to achieve a specific color impression, particularly a dark color, in addition to the effect pigment, it may be advantageous for at least one additional pigment, particularly an absorption pigment or a white pigment, to be included in the coating film.

[0057] Naturally, it is also possible for the coating film not to contain an effect pigment.

[0058] As described above, the coating film according to the embodiment is formed as a single layer and is already formed to have both scratch resistance and sealing properties as a single layer.

[0059] The fact that the coating film is formed as a single layer does not mean that the glass or glass-ceramic plate according to the embodiment must contain only a single coating film on the surface of the plate on which the coating film is also disposed. It is possible that one or more additional coating films are disposed on that surface, and in some cases it may be preferable for various reasons. However, the additional coating film does not determine the characteristics of the first coating film, and may be applied, for example, as a functional layer for the operation of electronic components or the like. In this case, the advantageous characteristics of the coating film can be determined in the region of the glass or glass-ceramic plate where no additional coating film is disposed between the substrate and the coating film or on the coating film itself, and only the coating film itself is disposed.

[0060] In this way, the inventors have first opened up the possibility of providing a coating film that is suitable as an undercoat or backcoat even when it is a single layer. As described, this is advantageously made possible by specially configuring the coating agent so that the coating agent contains two organosilicon precursors. Here, the inventors presume that the addition of the silicone resin plays a role in ensuring sufficient sealing properties.

[0061] Therefore, according to one aspect, the present invention also provides a method for manufacturing a glass or glass-ceramic plate according to an embodiment of the present disclosure, comprising: - providing a glass or glass-ceramic substrate; - providing a coating agent containing a pigment and a binder containing two organosilicon precursors, wherein one of the organosilicon precursors is a silicone resin and the other organosilicon precursor is a sol-gel hydrolysis product; - applying the coating agent to one side of the glass or glass-ceramic substrate to form a coating film, preferably by a printing method; - baking the coating film at a temperature of at least 200°C and at most 400°C for at least 10 minutes and at most 120 minutes, preferably at a temperature of at least 250°C and at most 330°C for at least 30 minutes and at most 90 minutes, particularly at most 60 minutes, and particularly preferably at a temperature of at least 300°C and at most 320°C for at least 30 minutes and at most 60 minutes relates to a method comprising

[0062] Such a method not only enables the production of a glass or glass ceramic plate according to an embodiment, but also has the advantage of facilitating process control. In particular, according to the method of the present disclosure, since only a single layer is now applied, that is, there is no need to store the inventory of various pastes in terms of logistics, the logistics cost related to production is significantly reduced. And when the desired color tone of the coating film is very thin, in some cases, there is no need to consider the change in chromaticity from above, that is, through the substrate, due to the application of a darker but sealing layer on top of the initially light-colored coating film. Because in exactly this combination, it could have happened before that if the first layer was not sufficiently opaque or was transparent, the chromaticity of the first coating film would change due to the darker back printing.

[0063] According to a further aspect of the present disclosure, the present invention further relates to a glass or glass ceramic plate manufactured by or at least manufacturable by the method according to an embodiment.

Examples

[0064] The following table shows, as an example, the compositions of three coating agents or pastes from which a glass or glass ceramic plate according to an embodiment can be obtained.

[0065]

Table 2

[0066] The exemplary paste composition according to the above table contains, as solid components, in addition to the filler, a plurality of nacreous pigments, a white pigment, and graphite as a dark component here. The proportions of these components are variable and are used here in particular to achieve a particularly preferred chromaticity. Therefore, it is also possible to use other nacreous pigments or only one. As the white pigment, for example, TiO2 can be used. The general composition range of the coating agent or paste for manufacturing a glass or glass-ceramic plate according to the embodiment is summarized below:

Table 3

[0067] Regarding the pigments, namely the white pigment, nacreous pigment, and other pigments (in particular, absorption pigments such as spinel, i.e., including oxide-based pigments with particularly high thermal stability), the totals are shown respectively. Thus, the paste or coating agent can contain only one nacreous pigment or a plurality, in which case the total of all nacreous pigments contained in the coating agent is at most 53.9% by weight. Therefore, the coating agent can contain only one white pigment or a plurality, and in that case, the total of all white pigments is within the aforementioned limits, and the same applies to other pigments.

[0068] Furthermore, in addition to the nacreous pigment, other effect pigments may be included. However, the total of the nacreous pigment and other effect pigments shall not exceed 53.9% by weight. The other effect pigments can be based on, for example, Al2O3, SiO2, or borosilicate glass flakes and can have different coating films. By using such effect pigments, both a color impression and additional effects such as a glitter effect or a metallic effect can be achieved.

[0069] An example of the composition for producing a sol-gel hydrolysis product is shown in the following table:

Table 4

[0070] Silane was charged, and p-toluenesulfonic acid was dissolved in water and added. After stirring for 1 hour, the obtained ethanol was distilled off.

[0071] [Table 5]

[0072] The present invention will be further described below with reference to the drawings. [Brief Description of the Drawings]

[0073]

Figure 1

Figure 2

Figure 3

[0074] Figure 1a shows a scanning electron microscope image of a prior art glass or glass-ceramic plate 10 including a coating film 2 configured as a two-layer system. The glass or glass-ceramic plate 10 is formed here as a glass-ceramic plate, that is, in this case, it includes a substrate 1 containing glass-ceramic. As can be clearly seen, the coating film 2 includes two different layers (or sub-layers) 22, 21. One layer 21 is arranged so as to face the substrate 2 and is a color-forming layer, and the other layer 22 is arranged on the first layer 21. In Figure 1a, a boundary line (or interface) 23 between the first layer 21 and the second layer 22 is schematically drawn. As can be seen from the scanning electron microscope image of Figure 1a, the second sealing layer 22 has a different microstructure, for example, it has a matrix 221 formed in a granular shape rather than the matrix 211 of the layer 21.

[0075] In contrast, a glass or glass-ceramic plate 10 according to an embodiment of the present disclosure is also formed as a glass-ceramic plate here, that is, it is formed as a glass-ceramic plate including a base material 1 containing a glass-ceramic and a coating film 2. The coating film 2 is formed here as a double layer in the form of a paste having the same composition printed twice, and as a result, a coating film including two sub-layers is obtained accordingly. As described, such a coating film 2 is called a single layer within the scope of the present disclosure because the two sub-layers forming it have the same composition. Here, the two sub-layers having the same composition have very good adhesion to each other because their compositions are the same, and it is difficult to distinguish them in the scanning electron microscope image of FIG. 1b.

[0076] In contrast to this, there is a two-layer system with different compositions in which layers 21 and 22 are present, as illustrated in FIG. 1a.

[0077] FIG. 2 shows a photographic image of a sample of a glass or glass-ceramic plate 10 for explaining oil resistance. The back surface of the coating film 2 of different plates 10 is shown in FIG. 2b, and the same plate 10 can be seen in FIG. 2a, but here the plate is photographed with the base material 1 facing upward, that is, facing the viewer.

[0078] In FIG. 2b, the residue of the coloring oil can still be clearly seen on the back surface of the test piece (a bluish stain, a dark shadow in the monochrome photograph). In FIG. 2a, the samples are shown in the same order as in the photograph of FIG. 2a, but there is an obvious difference in the appearance of the oil here: the sample on the left has a clearly visible stain, which means that there is also a large change in chromaticity corresponding to it, but the stain on the central sample is very difficult to visually recognize. In the sample on the right, in contrast to the other two samples, the stain can no longer be seen through the base material. This can also be proven by the corresponding measurement of chromaticity in the comparison between the treated and untreated ones, and it is known here that the chromaticity difference ΔE is less than 2, and here it is even as small as 0.22.

[0079] Figure 3 shows two photographic images of a test piece on which a scratching test, in particular DIN-ISO 1518-1, has been carried out. For this purpose, a test tip is drawn with a defined contact (defined by the contact force) on the surface of the coating, particularly preferably in the area where only the coating has been applied to the substrate.

[0080] This test is, within the scope of the present disclosure, - considered to be a pass if the trace of the test needle is not visible to an obstructive extent from above, i.e., when viewed through the substrate, or - if no peeling of the coating has occurred. is considered to be a pass.

[0081] It is advantageous that the trace of the test needle is not visible from above, i.e., through the substrate. This is particularly important in coatings containing effect pigments. Because, as can be seen from the trace of the test in Figure 3a, in the case of a coating having a so-called "metallic effect", even before the coating visibly peels off, damage to the layer that can be visually perceived through the substrate may occur. The inventors assume that this can be attributed to the "crushing" of the effect pigment, and thus, in the visual impression through the substrate, a difference between the unloaded coating and the area of the coating having the trace of the test is assumed to be perceptible. However, this occurs, if at all, only after applying a load of 7 N or more, which is much later than in the case of the plates according to the embodiments, as opposed to the plates of the prior art.

[0082] Thus, the coating has a scratch resistance of more than 7 N, preferably up to a maximum of 30 N, in a test according to DIN-ISO 1518-1 in the area of a glass or glass-ceramic plate where only the coating is disposed on the glass or glass-ceramic substrate.

[0083] Advantageously, the scratch resistance can also be more than 16 N, for example up to 17 N or even up to 18 N, particularly when considering delamination. Thus, according to one embodiment, it is possible to set the scratch resistance to 16 N or more, i.e., according to this embodiment, no delamination occurs at the mentioned load in the scratching test.

[0084] However, too high scratch resistance is correlated with too good adhesion of the layer, which may lead to a significant decrease in the mechanical durability of the plate. Therefore, in the case of a coating film (bottom coat or back coat) that is supposed to be disposed on the surface of the plate turned away from the user, this is disadvantageous. Accordingly, according to one embodiment, the scratch resistance of the coating film is at most 30 N.

[0085] Here, within the scope of the present disclosure, the expression "in the region of the glass or glass-ceramic plate where only the coating film is disposed on the glass or glass-ceramic substrate" is generally understood to refer to the surface on which the coating film is disposed in this case. On the other side of the plate, another coating film, such as a ceramic decoration for cooking zone marking, may be further applied. However, as can be easily understood by those skilled in the art, for the scratch resistance and also the oil resistance of the coating film, only the adhesion of the coating film to the substrate or its inherent sealing property is important, and of course, not the further coating film such as the top decoration disposed on the opposite side of the plate as required.

Explanation of Reference Numerals

[0086] 1 Glass or glass-ceramic substrate 10 Glass or glass-ceramic plate 2 Coating film 21, 22 Sub-layers of 2 23 Boundary line / interface between 21 and 22 211 Matrix, binder phase of 21 221 Matrix, binder phase of 22

Claims

1. A glass or glass-ceramic plate comprising a glass or glass-ceramic substrate and a coating film containing an organosilicon matrix and a pigment disposed on at least one surface of the glass or glass-ceramic substrate, wherein the coating film has a thickness of at least 10 μm, preferably at most 80 μm, and the coating film has a scratch resistance of more than 7 N, preferably at most 30 N, in a test according to DIN-ISO 1518-1 in a region of the glass or glass-ceramic plate where only the coating film is disposed on the glass or glass-ceramic substrate, and an oil resistance of less than 1, preferably less than 0.5, particularly preferably less than 0.3, very particularly preferably less than 0.2, most preferably less than 0.1, determined as a color change ΔE when measured through the glass or glass-ceramic substrate, where the color change ΔE is L ＊ a ＊ b ＊ in the colorimetric system by the following formula: 【Number 1】 A glass or glass-ceramic plate provided by [

1. ].

2. The glass or glass-ceramic plate according to Claim 1, having a flexural strength of at least 140 MPa, preferably at most 250 MPa, measured by the double-ring method in accordance with EN 1288-5 when determined as the arithmetic mean value over the entire sample of at least two samples.

3. The glass or glass-ceramic plate according to Claim 1 or 2, having an impact resistance of at least 45 cm, advantageously at least 60 cm, advantageously at least 70 cm, advantageously at least 80 cm, particularly preferably at least 90 cm, measured by a ball-drop test in accordance with UL 858 when determined as the arithmetic mean value over the entire sample of at least two samples, where the impact resistance is determined for a coating disposed on the lower surface of the glass or glass-ceramic plate.

4. The glass or glass-ceramic plate according to any one of Claims 1 to 3, having a light transmittance of less than 0.08%, preferably less than 0.04%, particularly preferably less than 0.02%, measured in accordance with DIN 5036 Part 1 in the region where the coating is disposed.

5. The glass or glass-ceramic plate according to any one of Claims 1 to 4, wherein the ratio of pigment to binder in the coating is 1:0.8 to 1:3, advantageously 1:1 to 1:2.5, particularly preferably 1:1.3 to 1:2, based on the respective weight ratios.

6. The glass or glass-ceramic plate according to any one of Claims 1 to 5, wherein the coating contains an effect pigment, and the ratio of the effect pigment to the total pigment ratio is 50% by weight to 100% by weight, preferably 70% by weight to 100% by weight, particularly preferably 88% by weight to 98% by weight.

7. A method for manufacturing a glass or glass-ceramic plate, in particular the glass or glass-ceramic plate according to any one of Claims 1 to 6, comprising: - providing a glass or glass-ceramic substrate - Provide a coating agent comprising a pigment and a binder containing two organosilicon precursors, wherein one organosilicon precursor is a silicone resin and the other organosilicon precursor is a sol-gel hydrolysis product, step; - Apply the coating agent to one side of the glass or glass-ceramic substrate to form a coating film, preferably by a printing method; - Bake the coating film at a temperature of at least 200°C and up to 400°C for at least 10 minutes and up to 120 minutes, preferably at a temperature of at least 250°C and up to 330°C for at least 30 minutes and up to 90 minutes, particularly up to 60 minutes, particularly preferably at a temperature of at least 300°C and up to 320°C for at least 30 minutes and up to 60 minutes A method comprising.

8. The ratio of the sol-gel hydrolysis product to the silicone resin in the coating agent is 1:0.2 to 1:0.02, preferably 1:0.09 to 1:0.035 by weight, according to the method of claim 7.

9. A glass or glass-ceramic plate produced or producible by the method according to claim 7 or 8, particularly according to any one of claims 1 to 6.

Images