Glass pane comprising a coating applied in at least one area of at least one side of the glass pane, composite comprising such a glass pane and method for producing such a glass pane

Abstract

The present disclosure relates generally to glass panes, in particular to glass panes coated in regions which can be used, for example, for a vehicle, as well as to a composite comprising such a glass pane and to a method for producing such a glass pane.

Description

Field of the invention

[0001] The present disclosure generally relates to glass panes, in particular to partially coated glass panes that can be used, for example, for a vehicle, as well as to a composite comprising such a glass pane and a method for producing such a glass pane. The glass pane comprises a glass comprising SiO2, Na2O, and CaO. Therefore, the present disclosure also relates in particular to glass panes made of or comprising soda-lime glass. Background of the invention

[0002] Glass panes made of or comprising soda-lime glass, in particular those which are coated at least in some areas, have been known for a long time and are used, for example, in the construction industry.

[0003] However, soda-lime glass can also be advantageous for other applications, as its production takes place at lower temperatures than that of borosilicate glass, for example, and is therefore less energy-intensive and thus more cost-effective. Therefore, large-scale products, such as building window panes and exterior vehicle glazing, are often manufactured from soda-lime glass.

[0004] The use of soda-lime glass in exterior vehicle glazing, for example, has long been known. This type of glass is well-suited for laminated glazing and its use in windshields, and it exhibits sufficiently high transmission in the visible light range.

[0005] For the safety of vehicle occupants, windshields are made of laminated glass and usually have a coating in the edge region. This coating serves both to visually conceal adhesive bonds or components such as antennas, and also to protect them from UV radiation. This frame is usually arranged between the two glass panes of a laminate. The laminate also comprises a polymeric layer, i.e. a layer comprising or made of a polymer, between the two glass panes, which bonds the glass panes together. The glass panes, with the coating arranged between them in at least one area, particularly in the edge region, are placed on top of one another and bent in a thermal forming process.A polymeric layer is then placed between both panes and the curved glass panes are bonded together to finally produce a laminated glass pane (which is also referred to simply as a “laminate” in the context of the present disclosure).

[0006] Glass panes enclosed in such a composite are therefore subject to a number of requirements. Since the bending processes are thermal, the glass panes and the coating applied to them must be able to withstand these temperatures. The glass panes and the coating must be able to bond with the polymer layer in such a way that a stable bond is formed and delamination between the glass and polymer does not occur. Finally, the coating must be sufficiently optically impermeable so that components arranged in the frame area of the windshield are not disruptively visible. This prevents distraction for the driver and thus increases driving safety. Microcracks or other defects in the coating must also be avoided wherever possible or at least minimized.

[0007] In addition to the temperature resistance of the glass and coating, the aforementioned compatibility of the glass or coating with a polymeric material to form a composite, the optical density, and the minimization of potential defects, the mechanical strength, exemplified by the fracture strength, of a coated glass pane also plays a role. It is known that coatings, especially particularly adhesive coatings, can impair the strength of a glass pane. Particularly adhesive coatings such as glass-based coatings can critically reduce mechanical strength, such as fracture strength or flexural strength.This applies in principle to all glass substrates, but even more so when the uncoated substrate, in this case the uncoated glass pane, has good, sufficient but not outstanding mechanical strength, as is the case with soda-lime glass panes, unlike borosilicate glass panes. For example, when using common ceramic paints, the loss of strength can result in coated glass panes with very low strength.

[0008] So-called sol-gel coatings or sol-gel layers on glass have also been known for a long time.

[0009] While such sol-gel layers were formed as thin oxide layers in the first commercial applications, which were used in particular for the production of optically effective coating systems on glass (for example in the commercially available products Amiran®, Conturan® and Mirogard®), the potential of sol-gel materials as binders for particle-based or particulate coatings has also become increasingly apparent.

[0010] For example, the German utility model DE 20 2008 003 804 U1 describes sol-gel coatings for glass composites. For example, the coating can be formed as a porous, sol-gel-based single layer, or the coating can be constructed as a multi-layer system of layers with different refractive indices. The coatings according to DE 20 2008 003 804 U1 do not contain any pigments and are explicitly intended to improve the luminous flux through the composite system. In the form of a single layer, they can be understood as an anti-reflective coating. If the glass composite according to DE 20 2008 003 804 U1 is a two-pane composite, the sol-gel layers are also arranged on the side of the pane facing outwards, i.e., on the side facing away from the other pane of the composite.

[0011] US 2013 / 0266781 A1 describes a coating structure of pigmented coatings obtained with a sol-gel-based binder. The coating structure comprises two coatings, one of which, usually color-imparting and applied directly to the substrate, is a pigmented coating with a sol-gel-based binder. This at least one coating is porous to prevent the passage of fluids, so that a further pigmented coating with a silicone binder is applied to the at least one coating as a sealing layer. This results in a glass or glass article provided with a decorative coating system, for example, for use as a cooking surface. A composite of multiple panes is not addressed.

[0012] US 2009 / 0233082 A2 describes glass or glass-ceramic articles with a decorative coating. The decorative coating comprises at least one decorative pigment and a sol-gel binder, resulting in a ceramic-like structure of the decorative coating after curing and firing. The coating therefore also comprises a high proportion of pigment, in particular significantly more pigment than binder, based on weight. A composite is not described.

[0013] French patent application FR 3 084 355 A1 describes an enameled substrate in which the enamel layer is porous. In addition to the porous enamel layer, the substrate may have another layer, for example, a silicon-based porous sol-gel coating, which is designed as a transparent functional layer and accordingly does not contain any pigments.

[0014] US 2015 / 0225285 A2 describes a method for printing on glass. A glass substrate is first coated with an adhesion promoter, after which one or more layers are printed using an ink. After this printing, the coating or coatings can be cured. Furthermore, it is possible to apply additional layers to these coatings, for example, by laminating a film. A composite pane comprising two glass panes is not described, nor is a pigmented, sol-gel-based coating.

[0015] US 2010 / 0047556 A2 describes a decorative coating for glass or glass-ceramic articles. The decorative coating comprises platelet-shaped pigments and a solid lubricant, with a weight ratio of pigment to lubricant between 10:1 and 1:1. The applications of the articles are primarily related to cooktops. Laminated glass panes are not addressed.

[0016] US 2010 / 0028629 A2 also describes glass or glass-ceramic articles with a decorative coating. The coating comprises two coating layers, of which the layer applied to the substrate, also referred to as the sealant, contains platelet-shaped pigments and a solid lubricant, with the weight ratio of pigment to lubricant being between 10:1 and 1:1. The applications of these articles particularly concern cooktops. Laminated glass panes are not addressed.

[0017] Finally, European patent application EP 3 830 046 A1 describes an enameled substrate in which the enamel layer is porous. In addition to the porous enamel layer, the substrate may comprise further layers, for example, a silicon-based porous sol-gel coating designed as a transparent functional layer and accordingly not comprising any pigments. The sol-gel layer may, in particular, be designed as a porous, anti-reflective coating with a low refractive index of 1.3 or less.

[0018] The sol-gel layers described above are either not intended for use in a laminate, especially not as an intermediate layer of a laminate, or are not pigmented. Nor are they intended for use in composite panes, especially curved composite panes, with sufficiently high strength.

[0019] There is therefore a need for coated glass panes that at least mitigate the aforementioned weaknesses of the state-of-the-art panes and their manufacturing processes. There is also a need for a composite pane that includes such a coated glass pane. Object of the invention

[0020] The object of the invention is to provide a glass pane, in particular a partially coated glass pane for a vehicle, and a composite comprising such a glass pane, which at least partially overcome or at least mitigate the aforementioned weaknesses of the prior art. Summary of the invention

[0021] The object of the invention is achieved by the subject matter of the independent claims. Preferred and specific embodiments can be found in the description, the figures, and the dependent claims of the present disclosure.

[0022] The disclosure thus generally relates to a glass pane, in particular a partially coated glass pane, such as a partially coated glass pane for a vehicle. The glass pane generally comprises a glass comprising SiO2 and Na2O and CaO, i.e. is preferably designed as a soda-lime glass pane, and at least one coating applied in at least one region of at least one side of the glass pane. The at least one coating comprises at least one binder comprising SiO2 and at least one pigment and preferably at least one additive designed as a filler. The at least one coating comprises less than 500 ppm Bi2O3 and / or less than 500 ppm ZnO and / or less than 500 ppm B2O3 and / or less than 500 ppm of an alkali oxide, in each case based on the weight of the coating.

[0023] This design has a number of advantages.

[0024] Thus, the glass pane preferably has a flexural strength of between at least 50 MPa and at most 300 MPa, preferably at least 100 MPa and at most 300 MPa, particularly preferably at least 150 MPa, in the at least one region which has the applied at least one coating on at least one side of the glass pane.

[0025] Generally, this strength value applies to the entire glass pane, so it can also be determined, for example, on a glass pane that is not fully coated. However, it has been shown that, for glass panes according to embodiments that have a coating as described in the present disclosure, this very good strength is also maintained in the coated area.

[0026] This very good flexural strength of the coated glass pane comprising a glass comprising SiO2, Na2O, and CaO, i.e., preferably the coated soda-lime glass pane, advantageously results from the design of the at least one coating, which comprises a binder comprising SiO2, but at the same time less than 500 ppm Bi2O3 and / or less than 500 ppm ZnO, again in each case based on weight, and / or less than 500 ppm B2O3 and / or less than 500 ppm of an alkali oxide, in each case based on weight. This is due to the special design of the coating, which, according to a preferred embodiment, is designed as a sol-gel coating.

[0027] Thus, according to the present disclosure, the advantage of a glass-based coating, i.e., a coating with an inorganic, amorphous (in particular X-ray amorphous) binder, can be easily combined with the good strength of a resulting coated glass pane. The good strength of the resulting coated glass pane, which is particularly evident in the flexural strength, which preferably lies within the aforementioned limits, results in particular from the fact that the present at least one coating, although it comprises SiO2, is not designed as a glass flux-based coating and therefore can be, and preferably is, cured or baked at temperatures that are not too high, in particular compared to glass flux-based coatings. For example, with the coatings according to embodiments, temperatures of up to 400°C are sufficient for baking, for example temperatures of around 380°C.This is particularly advantageous considering the differences in the thermal expansion coefficient that arise between the coating and the substrate, in this case the glass pane, which can contribute to a reduction in strength. While a glass flux-based coating also offers the advantage of a glass-based coating with high thermal, mechanical, and / or chemical resistance—depending on the precise composition of the glass flux used—it must be fired at higher temperatures, which not only melts the glass flux itself, but also at least partially melts part of the surface of the glass substrate, forming a so-called "melting reaction zone."The melting process is not only more energy-intensive than the curing / baking of the at least one coating according to the present disclosure, but also reduces the strength of the coated glass pane compared to its initial strength due to this melting of the surface of the glass pane.

[0028] The low firing temperature of the coating according to embodiments of the disclosure is also advantageous in comparison with the firing temperature of glass flux-based coatings because the bending process, which is often required for a composite for which a glass pane according to embodiments can be used, is generally not based on the firing temperatures of the coating, but solely on the substrate and the T g (transformation temperature of the glass, glass transition temperature) of the substrate, which is lower for soda-lime glasses than for borosilicate glasses.

[0029] If soda-lime glass is used as a substrate, the maximum usable temperatures for bending the substrate, such as a windshield, are reduced to approximately 600 °C. Therefore, glass-based inks with a melting behavior below 620 °C cannot be used.

[0030] Although several glass fluxes exist that address the problem of reduced firing temperatures, particularly glass fluxes based on Bi2O3 or ZnO, the inherent strength reduction remains even in the case of soda-lime glasses, and even in glasses with higher expansion coefficients. This reduction results from partial melting of the glass surface and the tensile stress that builds up due to the mismatched expansion coefficient of the glass flux compared to the substrate during cooling of the composite after bending.

[0031] This problem can be addressed with the at least one coating according to the present disclosure, in which the coating comprises a binder comprising SiO2, which is not a glass flux. According to one embodiment, the binder according to the present disclosure can in particular be a sol-gel binder, in particular one based on SiO2, so that a coating is obtained with a binder consisting predominantly of SiO2, i.e., more than 50% by weight, preferably even more than 90% by weight. The at least one coating generally comprises the components ZnO and Bi2O3, which are characteristic of a glass flux, in amounts of less than 500 ppm each, based on weight.Nevertheless, with such a coating, the advantageous properties of a glass-based coating, in particular good thermal and chemical resistance, can be obtained while maintaining good mechanical strength of the coated glass pane.

[0032] Such a coating, comprising at least one binder comprising SiO2, which is designed as a sol-gel binder and / or filler, applied to a soda-lime glass substrate, does not melt even at temperatures required for bending the substrate, for example, a windshield. Therefore, the firing or drying of the coating on the substrate and the bending of the coated substrate can advantageously be carried out in a single step. Separate steps, preferably firing first, followed by bending, are also possible.

[0033] The flexural strength of the (coated) glass pane in the coated area is preferably at least 50%, preferably more than 75%, of the flexural strength of the uncoated glass pane. Particularly preferred and surprisingly achievable is even an improved flexural strength compared to the uncoated pane, i.e., a flexural strength of more than 100% of the flexural strength of the uncoated glass pane. Mechanical strength, such as flexural strength, is a statistical value, so that, of course, the same pane would not be tested for flexural strength before and after coating. Rather, this statement refers to tests conducted on uncoated glass panes and coated glass panes of the same composition and design.For the purposes of this disclosure, flexural strength refers to the strength of the glass pane, also known as double-ring bending tensile strength, which was determined in accordance with DIN 1288-5. For the purposes of this disclosure, the arithmetic mean is used as the strength value.

[0034] It is generally advantageous to form the binder as a compound comprising SiO2. This generally enables good chemical and thermal resistance of the binder. Such binders can generally be or comprise silicones, polysiloxanes, polysilsesquioxanes, or partial hydrolysates of siloxanes, and mixtures thereof. These binders are collectively referred to in this document as sol-gel binders. If these binders or their precursor materials contain organic components, these may remain in the resulting coating after curing and, if applicable, thermal firing, but may also be largely burned out, depending on the precise composition of the precursor materials and the respective firing procedure.

[0035] Alternatively or additionally, according to the disclosure, the at least one coating comprises less than 500 ppm of an alkali oxide. In the present disclosure, an alkali oxide is understood to mean the oxide of an alkali metal. In particular, according to one embodiment, the coating comprises less than 500 ppm of Na2O and / or K2O and / or Li2O. The ppm specification here—generally always within the scope of the present disclosure—refers to the weight.

[0036] Alternatively or additionally, the at least one coating according to the disclosure comprises less than 500 ppm of B2O3. B2O3 is a frequently used component in glass fluxes for panes, particularly used to contribute to lowering the melting temperature of the glass flux and / or to achieving the lowest possible thermal expansion of the resulting coating. The absence of this component therefore underscores the design of the at least one coating as a glass-based, but not a glass-flux-based, coating.

[0037] The at least one coating is formed as a sol-gel coating. A sol-gel binder is generally understood to be a binder in which at least one component is a component formed by a hydrolysis-condensation reaction from an organosilicon precursor, for example, obtained by the acid-catalyzed hydrolysis and condensation of compounds such as tetraethyl orthosilicate (TEOS) or related or similar compounds. There is considerable variation in the preparation of such binders, and a mixture of different precursors is also possible, for example, the addition of predominantly inorganic, particle-based sols or the addition of so-called polysiloxanes and / or silicones, all of which are subsumed under the broad term "sol-gel binder" within the scope of this disclosure.

[0038] The advantage of sol-gel binders made of or comprising SiO2 is not only their great flexibility in composition, but also their good compatibility with glass-like substrates such as glass and glass ceramics of diverse compositions. Such a binder can be particularly advantageous for glass or glass ceramic substrates with not too high thermal expansion coefficients, since this not only ensures good bonding of a coating, such as the at least one coating of the glass pane according to the disclosure, but also allows a low linear thermal expansion coefficient of the coating to be achieved by using SiO2 as a binder.

[0039] The advantage of a coating comprising a sol-gel binder is that it ensures that relatively low firing temperatures, for example less than 450°C or even lower, for example 400°C or less, are sufficient for the firing of the at least one coating.

[0040] The pane according to the present disclosure, with a sol-gel-based coating, does not reduce the mechanical strength of the soda-lime substrate, despite the very high difference in the thermal expansion coefficients of the two materials. Furthermore, it does not exhibit delamination during a subsequent bending process. The sol-gel coating can be baked at low temperatures, namely below 400°C, so that temperatures below 620°C can be used in the bending process without disadvantage.

[0041] In this way, it is then easily possible for the glass pane to have very high flexural strengths, which cannot be achieved, for example, with conventional, glass-based, particularly enamel coatings, but under certain circumstances also with silicone-based coatings. The combination of at least one coating comprising a sol-gel binder with a glass pane comprising SiO2 and B2O3 is also advantageous for this purpose. The glass pane comprises, as explained above, a so-called soda-lime glass or, in other words, is designed as a soda-lime glass pane. This type of glass material (or glass for short) is material that has a linear thermal expansion coefficient between 7 * 10- 6 / K and 12 * 10- 6 / K, preferably between 8.5 * 10- 6 / K and 9.5 * 10- 6 / K and which comprises at least 71 wt.% SiO2 to at most 75 wt.% SiO2 and / or at least 12 wt.% Na2O to at most 16 wt.% Na2O and / or at least 9 wt.% CaO to at most 15 wt.% CaO. Preferably, it does not comprise any B2O3, apart from usual impurities.

[0042] Together with the at least one coating according to embodiments, the already good strength of the glass pane can be maintained or advantageously supported and possibly even further improved.

[0043] It is generally possible for a coating to comprise multiple binders, for example, to be hybrid. For example, coatings are known that, in addition to a sol-gel component, comprise a glass flux-based component or an organic, polymer-based component. This may be necessary, for example, if certain properties cannot be achieved with a binder alone and, for example, organic components and the addition of an additional binder are required to achieve sufficient impermeability of the resulting coating.

[0044] However, this is not provided for in a preferred embodiment of the disclosure. Rather, according to this preferred embodiment, it is provided that the at least one coating comprises only a single binder, preferably a binder in the form of a sol-gel binder.

[0045] According to one embodiment, the degree of surface coverage of at least one side of the glass pane with the at least one coating is at least 10% and at most 80%, preferably at least 15% and at most 65% of the total surface of the side of the pane to which the at least one coating is applied. According to a further embodiment, however, full-surface coverage or a coverage of more than 80%, for example 90% or 95%, with the at least one coating is generally also possible. This is particularly recommended for applications in which the glass pane and / or a composite made therefrom is used not as a viewing pane, but as a cover pane.

[0046] In the context of the present disclosure, a pane is generally understood to mean a plate-shaped shaped body. A glass pane (which may be coated or uncoated) is a pane comprising or made of glass. A shaped body is plate-shaped if its spatial dimensions in one spatial direction of a Cartesian coordinate system are at least one order of magnitude smaller than the spatial dimensions in the two other spatial directions of the Cartesian coordinate system perpendicular to the first spatial direction. In other words, the thickness of the shaped body is at least one order of magnitude smaller than its length and width. The two main areas or main surfaces of the pane, i.e. those whose size is determined by length and width, are also abbreviated to simply sides in the context of the present disclosure.

[0047] The sol-gel layer exhibits opacity. According to another embodiment, the reciprocal of the opacity, the visual transmittance, is τ vis , in the at least one region of the glass pane in which the at least one coating is arranged, at most 15%, preferably at most 10%, preferably at most 7% and particularly preferably at most 5%, most preferably at most 1%. According to one embodiment, τ vis at least 0.01%, preferably at least 0.05%, and preferably at most 0.3%. These values refer to an area in which the at least one coating covers the entire surface of the glass pane.

[0048] The at least one coating can be applied to the glass pane in at least one area so that it covers the entire surface, i.e., without any interruptions in the coating, but can also be arranged, for example, in the form of a so-called dot matrix. Combinations of these variants are also possible. For example, it is also possible for a coating applied to the entire surface of the glass pane, i.e., without any interruptions in the coating, to merge into a dot matrix in the edge region of the coating, usually towards the center of the glass pane. This is, for example, a common configuration of the at least one coating, which in this case is arranged in a structured manner on the glass pane, for glass panes used in vehicle windshields.

[0049] According to a further embodiment, the glass pane is designed such that in at least one partial area or within the entire at least one area of at least one side of the glass pane, a further coating is arranged on the glass pane, preferably a glass-based coating, in particular an enamel coating.

[0050] Such a configuration can be advantageous if the advantages of a sol-gel coating are to be realized with the at least one coating, but at the same time the advantages of an enamel coating are also desired. Especially for designs in which particularly good scratch resistance of the overall layer structure is necessary and / or desired, it can therefore be advantageous to apply a further coating, for example an enamel coating, to the at least one coating, which is in particular designed as a sol-gel layer. In this case, the at least one coating, which is applied first, acts as an intermediate layer and decouples the enamel coating from the glass pane, so that very good strength values are still achieved for the glass pane.At the same time, the additional coating acts as a top layer in the area in which it covers the at least one coating applied first and can thus, for example, significantly improve the scratch and abrasion resistance of the overall layer structure.

[0051] According to a further embodiment, the at least one coating comprises between at least 15 wt.% and at most 55 wt.% binder, preferably at least 20 wt.%, particularly preferably at least 25 wt.%. This is advantageous because it achieves an optimal compromise between good mechanical resistance of the at least one coating and good covering effect and sufficient strength of the coated glass pane.

[0052] According to a further embodiment, the at least one coating comprises between at least 15 wt.% and at most 30 wt.% pigment, based on the sum of all pigments comprised by the at least one coating. This is advantageous because it allows for a good covering effect of the at least one coating, especially in a single-layer structure, i.e., a structure in which only the at least one coating is applied, at least in part, to the glass pane.

[0053] The remainder of the coating is generally formed by fillers, for example, nanoparticulate fillers made of or comprising SiO2, but also other fillers as described in the present disclosure. However, SiO2-based fillers in particular are difficult to detect, partly because they bond well with the matrix of the sol-gel binder.

[0054] The at least one coating can generally comprise only one pigment. In the context of the present disclosure, a pigment is generally understood to mean a coloring matter, in particular a ceramic coloring matter, which provides a coating with a specific color and / or a specific visual appearance, for example, a so-called "metallic" effect. Thus, in the context of the present application, the term "pigment" generally includes so-called pure color pigments, in particular so-called ceramic pigments, preferably oxide pigments. Oxidic mixed oxide pigments, for example, with a spinel structure, can be very particularly preferred.Furthermore, the term "pigment" in the context of the present disclosure also includes so-called effect pigments, for example, mica-based pigments, as well as other effect pigments, in particular effect pigments in which a platelet-shaped substrate made of an oxidic material or mica-based pigment is coated. In the context of the present application, the statement that a coating, such as the at least one coating according to embodiments, or a paste, for example, a paste according to embodiments, comprises a pigment is generally understood to mean that they comprise a particulate color body, which therefore comprises particles, these particles having the composition of the corresponding pigment.Therefore, if in the context of the present disclosure it is mentioned that a coating or a paste comprises a plurality of pigments, this is understood to mean that the coating and / or the paste comprise pigment particles of different composition, namely according to the composition of the pigments comprised by the coating / paste.

[0055] The at least one coating can comprise only a single pigment. However, it is possible and may also be preferred for the at least one coating to comprise multiple pigments. For example, it can be provided that the at least one coating comprises a white pigment and a black pigment in order to be able to compensate for any batch-related fluctuations in the color coordinates of the pigments used in the usual way. Advantageously, the at least one coating can also comprise another pigment, for example an effect pigment, because such effect pigments, often platelet-based, can have a beneficial effect on the properties of a coating, such as its smoothness / surface quality, and thus also its mechanical strength, such as scratch and abrasion resistance.

[0056] According to one embodiment, the glass of the glass pane, i.e. according to one embodiment the soda-lime glass comprised by the glass pane, has a linear thermal expansion coefficient of between 7 * 10- 6 / K and 12 * 10- 6 / K, preferably between 8.5 * 10- 6 / K and 9.5 * 10- 6 / K. This glass exhibits a relatively high thermal expansion compared to borosilicate glass. This also makes it possible to design the glass pane from one of the long-established soda-lime glasses. This is particularly advantageous because these soda-lime glasses can be produced economically at high throughputs. It is advantageous that such glasses also benefit from the advantages of this coating.

[0057] According to a further embodiment, the glass of the glass pane comprises at least 71 wt.% SiO2 to at most 75 wt.% SiO2 and / or at least 12 wt.% Na2O to at most 16 wt.% Na2O and / or at least 9 wt.% CaO to at most 15 wt.% CaO. Such glasses are easily meltable and have sufficient chemical resistance, hardness, and strength. They are therefore particularly well suited for use in areas subject to mechanical stress, in particular, for example, as a viewing window in a vehicle, for example a windshield. Such glasses are also advantageous because they offer a good compromise between good mechanical, chemical, and thermal resistance on the one hand, and good meltability on the other, without tendencies towards segregation and / or excessive viscosity of the glass melt having a disruptive effect.Glass panes made of glasses such as soda-lime glasses with a thermal expansion coefficient within the aforementioned limits and / or with the components within the aforementioned limits are therefore preferred according to embodiments of the disclosure. It is particularly preferred to combine them in a composite, for example, as a laminate, with borosilicate glass panes.

[0058] According to a further embodiment, the at least one coating has a linear thermal expansion coefficient of at least 3 * 10- 6 / K and at most 10 * 10- 6 / K, preferably less than 9 * 10- 6 / K, particularly preferably less than 7.5 * 10- 6 / K, most preferably less than 6 * 10- 6 / K. This embodiment can be advantageously combined with such designs of the glass pane in which the linear thermal expansion coefficient of the glass of the glass pane is also limited and lies between 7 * 10- 6 / K and 12 * 10- 6 / K, preferably between 8.5 * 10- 6 / K and 9.5 * 10- 6 / K. In this way, glass panes comprising a pigmented coating comprising a sol-gel binder comprising SiO2 can be obtained in a particularly simple manner, which glass panes exhibit sufficient flexural strength. However, it is generally also possible to combine coatings with linear thermal expansion coefficients within the aforementioned limits with glass panes exhibiting a different linear thermal expansion coefficient, and vice versa. In this case, however, other measures are taken to compensate for the difference in the expansion coefficient. For example, this can be achieved by a so-called adaptation layer or intermediate layer as an additional coating.

[0059] Where reference is made to the thermal expansion coefficient in this application, this refers to the linear thermal expansion coefficient α. Unless otherwise stated, this is given in the range from 20 to 300 °C. The designations α and α 20-300are used synonymously within the scope of this invention. This can be determined, in particular, for glassy materials using a method according to ISO 7991. The thermal expansion coefficient of the coating is understood to mean the resulting thermal expansion coefficient of the corresponding coating, which results from the thermal expansion coefficients of the individual components of the coating, taking into account their contribution to the coating. Where reference is made to the thermal expansion coefficient of the glass pane within the scope of this application, this always refers to the thermal expansion coefficient of the glassy material (or glass) of the glass pane (i.e., the substrate).

[0060] According to a further embodiment, the glass pane has a thickness of between at least 1 mm and at most 12 mm. This represents a good compromise between sufficient strength and a still low weight of the glass pane used, especially if the glass pane is intended to be used in a composite with another pane.

[0061] According to a further embodiment, the at least one coating is microporous and / or has at most pores with a maximum lateral dimension, for example a diameter, of 1 µm. Surprisingly, it has been found that enamel-based coatings, which enable comparable strengths of the coated glass pane with the same coverage with the at least one coating, have a significantly different pore structure. It has been shown that enamel layers, which enable at least somewhat comparable strength (although this will generally always be lower than is the case with a coating according to embodiments) of the partially coated glass pane, have a quite high porosity with pore dimensions of more than 1 µm as the maximum lateral dimension, often with maximum lateral dimensions of several micrometers. Such coatings are therefore macroporous.Such pores can then increasingly form at the interface between the coating and the glass pane, i.e., between the coating and the substrate. The structure of the coating according to embodiments, however, is significantly different and features only a few, small pores. The maximum lateral dimension of a pore is understood to be its largest extension. Typically, the pores are ellipsoidal in shape, often with only a slight deviation from a spherical shape. The maximum lateral dimension can therefore also be approximately referred to as the diameter of the pores.

[0062] According to yet another embodiment, the glass pane has an optical density of at least 1 and at most 4.5, for example, at most 3, in the at least one region in which the at least one coating is arranged, for the coating thicknesses specified above. The optical density or color density is used to characterize the absorption behavior of a coating compared to "absolute white." The denser the color layer, the less light can pass through it. The optical density is calculated using the following formula: D=log(1R) R is the reflectance. The optical density is determined using densitometers, particularly within the scope of the present disclosure in the direction perpendicular to the largest areal extent of the coating and thus the coated surface of the coated glass pane. The higher the optical density, the less permeable the coating appears. This can be achieved particularly advantageously with a high pigment content and / or through the type and amount of the selected pigments in the at least one coating, and can be achieved precisely with pigment contents closer to the upper end of the aforementioned range between 0 wt.% and 30 wt.% pigment.

[0063] A paste is preferably used to produce the coating, in particular a paste for producing a coating, which is arranged as at least one coating on glass panes according to embodiments, and is thus also suitable for producing a glass pane according to embodiments, which is arranged at least partially on at least one side of the glass pane. The paste comprises at least one binder comprising SiO2, at least one pigment, at least one medium, and preferably at least one additive in the form of a filler.The binder comprising SiO2 is designed as a sol-gel binder, comprising at least one SiO2 phase crosslinked by hydrolysis and condensation of at least one semi-organic silicon oxide precursor phase, wherein a semi-organic silicon oxide precursor phase is understood to be a silicon compound in which an organic radical, in particular an alkyl radical, is bonded to the silicon atom directly or via an oxygen bridge atom. The paste is characterized in that the binder comprises less than 500 ppm Bi2O3 and / or less than 500 ppm ZnO. According to one embodiment, the binder can also additionally contain less than 500 ppm B2O3 and / or less than 500 ppm of an alkali oxide, wherein the statements made above regarding the binder with regard to the glass pane generally also apply correspondingly to the binder of the paste.

[0064] The medium can also generally be referred to as a dispersion medium. As explained, such a paste can advantageously be used to obtain a glass pane according to embodiments.

[0065] The paste is generally designed such that the binder comprising SiO2 is formed as a sol-gel binder, comprising at least one SiO2 phase crosslinked by hydrolysis and condensation of at least one semi-organic silicon oxide precursor phase, wherein a semi-organic silicon oxide precursor phase is understood to be a silicon compound in which an organic radical, in particular an alkyl radical, is bonded to the silicon atom directly or via an oxygen bridge atom. This is particularly advantageous because it allows for great flexibility with regard to the composition of the binder, despite the restriction to essentially pure SiO2 chemistry, which means that preferably at least 90% by weight of the inorganic constituent of the binder is formed by SiO2.Such semiorganic silicon oxide precursor phases are flexibly usable and crosslinkable and can also be combined with other SiO2 precursor materials, for example, precondensed and dispersed SiO2 nanoparticles, such as those commercially known under the trade name "Levasil," or with other dispersions of nanoparticles, in particular SiO2 nanoparticles, as will be explained below. It is also possible to use precursor phases in which the silicon atom has four oxygen bridge atoms, but also those in which at least one organic radical is directly bonded to the silicon atom. As stated above, alkyl radicals are particularly preferred.An alkyl group, especially a methyl group, directly bonded to the central silicon atom can be advantageous because it provides the coating with a certain inherent impermeability and resistance to water and water vapor, while also being highly compatible with organic components, such as a laminate film. It is particularly important that a methyl group has particularly high temperature resistance and is therefore preferred. Alternatively, a phenyl group could be substituted, but this is less temperature-stable and could potentially be hazardous to health if decomposed. In general, it is preferable to have no more than two organic groups per silicon atom in the precursor to enable efficient network formation.One organic group per silicon atom is preferred, such as methyl triethoxy silicate in the precursor phase.

[0066] According to one embodiment, the paste comprises between at least 10 wt.% and at most 40 wt.%, preferably at least 15 wt.% and at most 30 wt.%, of additive, preferably a filler, based on the total weight of the paste and based on the sum of the additives, preferably fillers, comprised by the paste.

[0067] In this way, a very advantageous compromise is achieved between improving the paste properties and / or the properties of the resulting coating through the addition of fillers and achieving a dense, as dark as possible, and color-neutral color coordinate of the resulting coating. An excess of fillers can also potentially adversely affect the opacity of the pigments used.

[0068] With regard to a filler, it is understood that it is a particulate substance, i.e., comprises particles, wherein these particles have the composition of the corresponding filler. Therefore, if, within the scope of the present disclosure, a coating or paste comprises multiple fillers, this is understood to mean that the coating and / or paste comprise filler particles of different compositions, namely, corresponding to the composition of the fillers comprised by the coating / paste.

[0069] According to one embodiment, the paste comprises a filler having a linear thermal expansion coefficient between -10 * 10- 6 / K and +10 * 10- 6 / K, i.e., one that preferably has a relatively low linear thermal expansion coefficient. In particular, it can be a preferably fumed silica, generally SiO2-based particles, or graphite. Such a relatively low linear thermal expansion coefficient between -10 * 10- 6 / K and +10 * 10- 6 / K is preferably between -8 * 10- 6 / K and +5 * 10- 6 / K, particularly preferably between -6.5 * 10- 6 / K and +3* 10- 6 / K, is particularly advantageous for a binder such as that used in the at least one coating according to embodiments, namely a binder comprising SiO2. This ensures good incorporation of the filler into the coating, and this can further improve the stability of the coating, in particular of the at least one coating of the glass pane according to the present disclosure, for example with regard to scratch and / or abrasion resistance.

[0070] Fillers as components of sol-gel pastes have been known for a long time. Such fillers can influence the properties of the paste containing them, as well as the resulting coating, in a variety of ways, and in particular, improve them by, for example, improving the crosslinking of a sol-gel matrix.

[0071] It is also possible to use fillers that serve, for example, as rheology additives in a sol-gel paste, but at the same time can also be easily integrated into the resulting coating and have additional functions, such as improving the abrasion of the coating.

[0072] As stated, according to one embodiment, it is also possible for the paste to comprise a further additive, for example a filler. Preferably, in the case where the paste comprises two or three fillers, this further filler, as stated, can also preferably be a filler with a relatively low linear thermal expansion coefficient, for example, with a linear thermal expansion coefficient between -10 * 10- 6 / K and +10 * 10- 6 / K is preferably between -8 * 10- 6 / K and +5 * 10- 6 / K, particularly preferably between -6.5 * 10- 6 / K and +3* 10- 6 / K.

[0073] As also explained above, fillers with a thermal expansion coefficient in the aforementioned range can generally be particularly advantageous for developing the properties of the at least one coating and, accordingly, also the properties of the glass pane, whether as the sole filler or when multiple fillers are present. Furthermore, such fillers, particularly in the case of silica, can bring advantageous properties to the paste itself, for example by enabling or supporting the adjustment of the viscosity, for example a viscosity that is suitable for application by means of a printing process such as screen printing. Furthermore, the formation of the filler as a low-expansion filler can also be advantageous. However, it is not absolutely necessary for the filler to have a very low linear thermal expansion coefficient.As explained, the filler can indeed be graphite, which in this case has further advantages which outweigh the relatively high thermal expansion coefficient of this material compared to amorphous silica, especially when one considers that the binder itself is likely to have a rather low thermal expansion coefficient and the material of the glass pane according to one embodiment itself has a linear thermal expansion coefficient in the range between 2*10-. 6 / K and 6*10- 6 / K.

[0074] In general, as already explained above, fillers can fulfill very different functions in a paste and / or in the resulting coating. For the production of the at least one coating of the glass pane according to embodiments of the disclosure, it has been shown that it can be particularly advantageous if the paste comprises two types of fillers. Of course, the resulting coating can also comprise these two fillers, particularly in the case of high-temperature-stable fillers. However, in individual cases, and especially with relatively low filler contents, detection in the coating itself may be difficult under certain circumstances.

[0075] For example, according to one embodiment, a filler can be a silica, in particular a fumed silica. Such a configuration is advantageous because fumed silica—in other words, chemically amorphous SiO2—is not only a well-known material with readily available properties, but can also exhibit advantageous properties in a paste, for example, as a rheology additive. This eliminates the need to use, for example, organically modified rheology additives, which may be difficult to remove from the resulting coating, potentially leading to unsightly discoloration or other coating failure during subsequent use of the glass pane.Furthermore, a fumed silica remains in the coating and, due to its good integration into a sol-gel matrix based on SiO2, as is the case with the glass panes according to the present disclosure, can also further promote good crosslinking of the coating within the coating itself and also with the substrate. Since fumed silica, as amorphous SiO2, itself has only a low coefficient of thermal expansion and can also be produced in a variety of variants, the properties of the resulting coating can be specifically influenced in this way. A filler in the form of silica is therefore particularly advantageous according to one embodiment. It is precisely here that it becomes apparent that the filler is also present in the resulting coating, but in the case of a coating matrix consisting predominantly of SiO2, it is no longer detectable as such.However, the influence of the filler is reflected in the resulting advantageous properties of the coating obtained.

[0076] Another category of fillers, especially in the field of pigmented sol-gel coatings, are so-called "lubricants." A "lubricant," in the context of the present disclosure, is understood to be a solid that exhibits a "lubricating" effect analogous to that of talc. This effect arises because the filler in question, designed as a lubricant, itself has a platelet-like structure. Known and advantageous fillers used in sol-gel coatings include graphite or boron nitride. According to one embodiment, the paste preferably comprises graphite as a filler. This is also sufficiently thermally stable to be included in the resulting coating. However, it is not easily detectable, particularly due to the low atomic number of carbon, which is why it cannot be clearly visualized, for example, in an EDX analysis.

[0077] The beneficial effect of a lubricant such as graphite or boron nitride, which is reflected in the resulting good properties of the coating, is not fully understood by the inventors. However, it has been shown that such fillers with a platelet-like structure, especially with a graphite-like structure based on the crystal structure of the fillers in question, can be advantageous for the formation of particularly durable sol-gel-based coatings.

[0078] However, such lubricants also have some disadvantages. Until now, it was known that such fillers could achieve the desired properties, especially in sol-gel coatings, if a specific ratio of pigment to lubricant was present in the paste (and accordingly also in the resulting coating), ranging between 10:1 and 1:1 by weight.

[0079] In the case of graphite as a filler, this can provide some positive properties for the resulting sol-gel coatings, but it also leads to some undesirable properties. Since graphite itself is colorant, only relatively dark colors are possible for the corresponding coatings. However, it is difficult to achieve a truly dark, black color with such relatively high graphite contents. Since the pigments used in the state of the art mostly included effect pigments, the color palette using graphite as a lubricant has so far been very limited and mostly involved pastes from which light to dark gray coatings with a "metallic" effect were produced.In addition, with a very high proportion of graphite, which on the one hand was advantageous for the development of advantageous mechanical properties of the layer such as good adhesion, scratch and abrasion resistance as well as good sealing, the layer was also usually conductive, which was undesirable for certain applications.

[0080] An alternative to using graphite as a lubricant could be boron nitride, which can also be referred to as "white graphite." However, this results in the formation of a rather white or light-colored layer, which can be unfavorable for masking coatings, such as those used on the frames of glass panes intended for use as car windscreens in a composite window. Furthermore, boron nitride is expensive to produce and therefore unsuitable for energy efficiency and cost reasons.

[0081] Finally, it should be noted that wetting such a lubricant-coated coating can be difficult. While this may be advantageous for certain applications, there are concerns that an excessively high proportion of fillers designed as lubricants, as mentioned in the prior art, may be disadvantageous, particularly with regard to the subsequent lamination of a glass pane coated with a lubricant-containing coating. Therefore, there is a particular need for pastes for producing coatings for glass panes, which are used, for example, in a composite and where dark colors, especially dark black, are to be achieved.

[0082] Surprisingly, it has been found that, according to a particularly preferred embodiment, significantly smaller amounts of a lubricant than previously known can be sufficient in a paste and accordingly in a resulting at least one coating of a glass pane according to embodiments. If the filler is present as a lubricant, according to this preferred embodiment the ratio of pigment to lubricant is more than 20:1, preferably more than 30:1 and particularly preferably more than 40:1, based on the total weight of the sum of the pigments comprised in the paste or the resulting coating and the sum of the fillers formed as a lubricant, in each case based on the weight proportion of the respective constituents. In this way, not only is greater design freedom provided, for example in the provision of specific colors, for a resulting coating.Rather, this surprisingly enables both advantageous mechanical properties and still sufficient scratch resistance of a correspondingly produced coating, such as the at least one coating on a glass pane according to embodiments of the disclosure, while simultaneously avoiding the disadvantages of known layers from the prior art. In particular, the glass panes obtained in this way, comprising at least one coating, are well suited for lamination with another glass pane to form a solid composite that meets the requirements, for example, of a vehicle windscreen.

[0083] According to one embodiment, the paste comprises up to 50% by weight of a solvent, preferably a high-boiling solvent having a boiling point of at least 130°C and preferably at most 330°C, for example at most 220°C.

[0084] In particular, the solvent can be or comprise diethylene glycol monoethyl ether. This configuration is particularly advantageous for printing inks, as it creates a paste that is easy to print, for example, by screen printing, without drying out on the screen.

[0085] According to yet another embodiment, the paste comprises a solution of a cellulose, for example an ethylcellulose, preferably in a content between 5% and 10% by weight, based on the total weight of the paste. The cellulose can, for example, be dissolved in a high-boiling solvent, for example diethylene glycol monoethyl ether.

[0086] Such a paste configuration is not mentioned in the cited prior art documents. Until now, it was assumed that cellulose, which is advantageous, for example, for adjusting the viscosity of the paste, which is particularly advantageous for screen printing, cannot be used well in sol-gel-based pastes. This is because semiorganic SiO2 compounds are usually condensed under acidic conditions, meaning the pH of such a paste is relatively low, particularly below 7, and thus in the acidic range. However, cellulose decomposes in such acidic solutions, so that only pastes with a pot life of a few days could be obtained in this way.

[0087] The formation of the binder as a SiO2-comprising sol-gel binder is generally very advantageous. As explained, SiO2-comprising binders can be obtained, for example, by a hydrolysis-condensation reaction from organosilicon precursors or precursor compounds, for example, by the acid-catalyzed hydrolysis and condensation of compounds such as tetraethyl orthosilicate (TEOS) or related or similar compounds. There is considerable variation in the preparation of such binders, and a mixture of different precursors is also possible, for example, the addition of predominantly inorganic, particle-based sols or the addition of so-called polysiloxanes and / or silicones, all of which are subsumed under the broad term "sol-gel binder" in the context of this disclosure.

[0088] The advantage of sol-gel binders made of or comprising SiO2 is not only their great flexibility in composition, but also their good compatibility with glass-like substrates such as glass and glass ceramics of various compositions. Such a binder can be advantageous not only for glass or glass ceramic substrates with low thermal expansion coefficients, since this not only ensures good bonding of a coating, such as the at least one coating of the glass pane according to the disclosure, but also allows a suitable linear thermal expansion coefficient of the coating to be achieved by using SiO2 as a binder.

[0089] Pastes that can be used to obtain sol-gel-based coatings are described, for example, in US 2010 / 0028629 A2. US 2010 / 0047556 A2 also describes similarly structured sol-gel pastes. Finally, US 2009 / 0233082 A2 also describes pastes that can be used to obtain sol-gel-based coatings.

[0090] However, the coatings mentioned in the above patent applications are not suitable for the production of a glass pane according to the embodiments. Rather, the pastes described therein are intended for the production of coatings on a mostly glass-ceramic substrate with very low elongation, preferably a substrate with a linear thermal expansion coefficient of less than 2*10- 6 / K, namely LAS glass ceramics with low thermal expansion, such as those used for cooktops. The particular difficulties that arise when coating such a substrate with low expansion lead to the pastes and, accordingly, the resulting coatings having a different composition and structure than is appropriate for a glass pane according to embodiments that are also intended to be suitable for use as a glass pane in a vehicle glazing composite.

[0091] In particular, the layer systems mentioned in the above prior art documents usually comprise two layers that are applied in separate coating processes and show significant differences, particularly with regard to the ratio of individual components of the paste and - correspondingly - the resulting coating.

[0092] According to one embodiment, the paste comprises between at least 15% by weight and at most 30% by weight of pigment, based on the total weight of the paste and based on the sum of the pigments comprised in the paste. Preferably, the paste comprises at least 20% by weight of pigment.

[0093] In other words, the pigment content of the paste and, correspondingly, also of the at least one coating that can be obtained using the paste according to embodiments is significantly different from that of the known pastes. The different composition of the paste and, accordingly, of the at least one coating also leads to a different coating structure. Therefore, according to embodiments, it is also possible in the present case for the glass pane to have only a single coating, i.e., the at least one coating is the only coating.

[0094] According to one embodiment, the paste comprises between at least 8 wt.% and at most 20 wt.% binder, based on the total weight of the paste. Preferably, the paste is composed such that between 8 wt.% and 20 wt.% of the SiO2 content of the paste, based on the total weight of the paste, results from an organosilicon precursor.

[0095] In this way, sufficient adhesion between the at least one coating produced using the paste and the glass pane can be ensured. Sufficient scratch resistance can also be achieved in this way. Despite this relatively high binder content compared to known pastes or coatings resulting from such known pastes, the strength of the glass pane according to embodiments is not reduced below a critical value. This is due to the fact that the particularly strongly crosslinking component, namely the polymer-like crosslinked SiO2 framework resulting from the organosilicon precursor phase, is combined with nanoparticles. Thus, particularly high strengths of the resulting coated glass pane can be achieved according to embodiments of the disclosure.

[0096] According to one embodiment, the paste comprises at least 10 wt.% and at most 40 wt.% additive, preferably a filler, based on the total weight of the paste and based on the sum of the additives, preferably fillers, comprised by the paste.

[0097] The paste's content of additives, especially fillers, is therefore comparatively high, both in the paste itself and relative to the total amount of pigments comprised by the paste—and correspondingly by the at least one coating. According to one embodiment, at least one filler is in the form of a lubricant, in particular graphite, and the ratio of pigment to lubricant is more than 20:1, preferably more than 30:1, and particularly preferably more than 40:1, the total weight of the sum of the pigments comprised by the at least one coating and the sum of the fillers in the form of a lubricant, in each case relative to the weight fraction of the respective components.According to this embodiment, the ratio of the sum of the pigments comprised by the paste to the sum of the fillers formed as lubricants comprised by the paste corresponds to that which also occurs in the at least one coating according to one embodiment.

[0098] According to yet another embodiment, the paste comprises up to 50 wt.% of a solvent, preferably a high-boiling solvent with a boiling point of at least 150°C and preferably at most 330°C. In particular, the solvent can be or comprise diethylene glycol monoethyl ether. Such a configuration is particularly advantageous for printing inks, as it creates a paste that is easily printable, for example, by screen printing, without drying out on the screen.

[0099] According to yet another embodiment, the paste comprises cellulose, for example ethylcellulose, preferably in a content between 0.1 wt.% and 1 wt.%, based on the total weight of the paste. The cellulose can, for example, be dissolved in a high-boiling solvent, for example diethylene glycol monoethyl ether.

[0100] Such a paste configuration is not mentioned in the cited prior art documents. Until now, it was assumed that cellulose, which is advantageous, for example, for adjusting the viscosity of the paste, which is particularly advantageous for screen printing, cannot be used well in sol-gel-based pastes. This is because semi-organic SiO2 compounds are usually condensed under acidic conditions. While a pH value in the paste cannot be determined because the paste contains many organic solvents, and the concept of a pH value is not applicable to such solutions, it had been shown in known prior art pastes that cellulose decomposed, and thus only pastes with a pot life of a few days could be obtained. Surprisingly, however, it has been shown that cellulose can be used in the present pastes according to the disclosure.The inventors are not entirely clear why this is the case. It may be due to the dissolution of the cellulose in a suitable solvent, namely an ether such as diethylene glycol monoethyl ether, and the relatively low overall weight fraction of cellulose of at most 1% by weight.

[0101] The use of cellulose can be advantageous because it allows the viscosity parameters of the paste to be adjusted, resulting in a better printed image compared to the viscosity parameters of pastes without cellulose. Put simply, pastes containing cellulose have a rather "honey-like" viscosity, whereas pastes made viscous solely using silica exhibit very strong thixotropy, which can lead, for example, to an unfavorable, excessively "pixel-like" print image in a screen printing process. This can be counteracted by reducing the silica in the paste, but this can then lead to an overall viscosity that is too low and the ink "dripping" through the screen. However, these disadvantages can be mitigated in a surprisingly simple way by adding cellulose within the aforementioned limits.

[0102] The present disclosure also relates to a composite. The composite comprises a glass pane according to embodiments and another glass pane, wherein the at least one coating is preferably arranged between the two glass panes of the composite. In particular, a polymeric layer, particularly in the form of a film, can also be arranged between the two glass panes of the composite in the usual way, in order to form a laminated glass that can be used, for example, as a windshield or other vehicle glazing.

[0103] The glass pane and the additional glass pane can have the same glass composition or consist of the same glass type. Preferably, the additional glass pane consists of a different glass composition or a different glass type from the glass pane according to embodiments. It is particularly preferred that the additional glass pane is a borosilicate glass pane.

[0104] The value L* according to ISO / CIE 11664-4 “Colorimetry - Part 4: CIE 1976 L*a*b* Colour space” represents a measure of the colour location. In one embodiment, a composite comprising a glass pane according to the invention, another glass pane of the same glass type, preferably the same glass composition, with a thickness which deviates from that of the pane according to the invention by - 2.0 mm to + 2.0 mm, and a polymeric layer, preferably made of PVB, in the region in which the at least one coating covers the glass pane over its entire surface, has a value L*, measured in remission without gloss, of less than 15, preferably less than 10, particularly preferably less than 5.

[0105] In one embodiment, a composite comprising a glass pane according to the invention, another glass pane of the same glass type, preferably the same glass composition, with a thickness that differs from that of the pane according to the invention by - 2.0 mm to + 2.0 mm, and a polymeric layer, preferably made of PVB, in the region in which the at least one coating covers the glass pane completely, has a visual transmittance, τ vis , of at most 10%, preferably at most 7% and more preferably at most 5%, particularly preferably at most 1% and most preferably at most 0.5%. Examples

[0106] The invention is further illustrated below with reference to examples. The following table lists the compositions of pastes according to embodiments of the disclosure, with which coatings according to embodiments and, correspondingly, glass panes according to embodiments can be obtained.

[0107] The following Table 1 lists an exemplary composition of a SiO2-based sol as a component of the binder of the paste and, correspondingly, of the coating according to embodiments. As can be seen from the information in Table 1, this is the part of the binder of the paste that comprises a semi-organic silicon compound or is formed from such a compound by hydrolysis and condensation. Table 1: Sample weight [g] Substance name Crowd Unit molar mass 104,16 TEOS Tetraethoxysilane 0,5 mole 208,32 g / mol 178,3 MTEOS Methyltriethoxysilane 1 mole 178,3 g / mol Sample weight [g] Substance name Crowd Unit molar mass 1,78 p-TSH para-toluenesulfonic acid 0,01 mole 190,22 g / mol 9,011 H2O water 0,5 mole 18,022 g / mol

[0108] As can be seen from Table 2 below, in addition to this constituent obtained from hydrolysis and condensation of at least one semiorganic organosilicon precursor phase, further constituents can be added to the binder, i.e., the "semiorganic Si compound" or, more correctly, the binder produced from it, as described above by way of example. The binder thus obtained as a whole is understood in the context of the present disclosure as a sol-gel binder. Together with other components, such as pigments and / or fillers, the paste is then obtained, with exemplary compositions being set forth in the table below. Table 2: Paste No. 1 2 3 4 5 6 7 component [g] [g] [g] [g] [g] [g] [g] Silicone binder 6,00 Semi-organic Si compound 15,00 15,00 15,00 15,00 15,00 15,00 15,00 Nanoparticle dispersion (37%) in diethylene glycol monoethyl ether 60,00 60,00 60,00 60,00 60,00 60,00 60,00 Diethylene glycol monoethyl ether (DEGMEE) 9,73 9,73 Black pigment (Cr-Cu-Spinel) 3,00 0,00 3,00 3,00 10,00 3,00 3,00 White pigment (rutile) 0,00 2,92 0,00 0,00 0,00 0,00 0,00 Effect pigment 22,00 22,00 22,00 22,00 15,00 10,00 10,00 graphite 0,68 0,68 0,68 0,68 0,68 0,68 0,68 Soot (flame soot lamp black) 14,00 Carbon black (type Printex 95) 14,00 Silica 2,25 2,25 2,25 2,25 2,25 2,25 2,25 component [g] [g] [g] [g] [g] [g] [g] Cellulose in DEGMEE 10,00 10,00 10,00 10,00 10,00 Defoamers 0,20 0,20 0,20 0,20 0,20 0,20 0,20

[0109] The nanoparticle dispersion is a dispersion of nanoparticles, which here are SiO2 particles with an average grain size, based on the equivalent diameter in relation to the volume, of less than 1 µm, in diethylene glycol monoethyl ether, with the proportion of nanoparticles in the dispersion being 37 wt.%, based on the weight of the dispersion. Of course, it is also possible to add nanoparticles in another form, for example in the form of an aqueous sol, as is available, for example, under the trade name "Levasil." However, such a sol would have the disadvantage of a certain content of alkali oxide, in particular Na2O, and such a configuration is therefore not preferred.Preferably, the paste is therefore designed to comprise a dispersion of SiO2 nanoparticles in an organic solvent, preferably a high-boiling solvent, preferably having a boiling point of at least 130°C and preferably at most 330°C.

[0110] Carbon blacks can also be added to the paste and act as a pigment. Preferably, according to one embodiment, flame blacks can be used, for example, those with CAS No. 1333-86-4. Despite their nominally chemically identical composition to graphite, namely carbon, they are to be considered a pigment due to their precise production and the resulting different particle shape and the lower, if any, crystallinity compared to graphite and the associated different particle shape, and do not act as a lubricant within the meaning of the present disclosure. The addition of carbon black can be advantageous because it allows a particularly dense layer with a particularly black color impression to be obtained.Depending on the exact type of carbon black, the properties of the paste and also of the resulting coating can vary considerably; for example, it has been shown that Paste 7 described above, comprising a carbon black of the type "Printex 95", is difficult to remove from the screen and is therefore not easy to print.

[0111] Coatings were screen-printed onto a soda-lime glass pane using the pastes listed in the table above as numbers 1 to 6, using a fine screen (140 mesh) and a coarser screen (77 mesh). The carbon black-containing pastes were screen-printed using a 77 mesh screen.

[0112] These are thermally treated, ie dried or baked, at 380 °C for a few minutes or up to one hour, but can also be baked at higher temperatures such as 400 °C or 450 °C or, as in example A1, at 600 °C. Description of the drawings

[0113] Fig. Figure 1 is a schematic and not-to-scale representation of a laminated glass pane 10 according to an embodiment of the present disclosure. The laminated glass pane 10 comprises two panes 1, 2, wherein pane 1 and / or pane 2 is a glass pane for a vehicle according to an embodiment of the present disclosure. Preferably, pane 2 is a pane according to the present disclosure.

[0114] Preferably, a pane 1 consists of a different glass composition or a different glass type from pane 2. Particularly preferred is that pane 1 is a borosilicate glass pane. A polymeric layer 3 is arranged between the two glass panes 1, 2, as well as, here in the edge region of the composite 10, the coating 11. This is arranged on one side (not designated) of the glass pane 1 or the glass pane 2 and, within the scope of the following description, can comprise the at least one coating alone or together with the further coating as an intermediate layer.

[0115] For clarity, coating 11 has been depicted here as thick, comparable in thickness to that of the two panes 1, 2; however, as explained, this is merely for clarity. Coating 11 is generally significantly thinner than either of the two panes 1, 2 and usually also thinner than polymeric layer 3. Polymeric layer 3 can also be a film.

[0116] The composite 10 is, as can be seen, designed as a curved laminated glass pane, such as can be used as a windshield. In general, without limitation to the Fig. 1, it is also possible that the composite 10 does not comprise curved discs 1, 2, but is flat. It is also possible that the curvature of the composite 10 is just the opposite of that shown in Fig. 1. In the example of Fig.1, the glass pane 1 would be the outer side of a windshield. In any case, however, the coating 3 is arranged between the two glass panes 1, 2.

[0117] To clarify the structure of the glass pane 1 according to embodiments, this is shown in the Fig. 2 and Fig. 3 are each shown in the form of a schematic and scaled illustration. Fig. 2 shows a side view. Here, however, the glass pane 1 is not yet curved. In general, without limitation to the Fig. In the example of a glass pane 1 shown in Figure 1, it is also possible for the glass pane to be curved. However, it may be advantageous to initially use a flat, non-curved pane 1, which is then later bent, for example, using a thermal process. Here, too, for the sake of clarity, the thickness of the coating 11 is shown significantly larger than in reality.

[0118] The arrangement of disc 1 corresponds to that in Fig. 1, as stated with the exception that the disc in Fig. 2 is not bent. As can be seen, the coating 11 is formed here on the side 102 which, in the composite 10, faces the second pane 2, while the uncoated side 101 in the composite 10 faces away from the second pane 2. Not shown here is the polymeric layer 3 which, in the composite, is arranged between the pane 1 and the pane 2. It is expressly pointed out here that the polymeric layer 3 both directly contacts the side 102 of the pane and is arranged on the coating 11 arranged in the region (or regions) of the pane 1 (or the side 102 of the pane 1).

[0119] The coating 11 is arranged here in the edge area of the disc 1, in the illustration of the Fig.2 on the left and right, respectively. Here, for example, the coating may be applied in the form of a "frame."

[0120] For this purpose, reference is made to the Fig. 3, which also shows a schematic and not to scale illustration of a plan view of a pane 1 according to one embodiment. The coating 11 is designed here as a frame surrounding the edge of the pane 1, wherein the coating is initially opaque, i.e., as a layer without interruptions, and merges into the uncoated area towards the center of the pane 1 via a grid or dot pattern 111. This uncoated area is, in the case of use of the pane 1 in a composite 10, the viewing area, for example, of a windshield. Of course, it is generally possible that the frame is not as uniformly formed as schematically in Fig.3, but has bulges, for example, as is often the case with windscreens in the area of the rear-view mirrors.

[0121] In one embodiment of the disclosure, the pane 1 is provided with a coating 11 arranged on side 102 of the pane 1. The coating comprises pigments, wherein only one exemplary pigment 4 is designated here, which is a platelet-shaped pigment, i.e., a so-called effect pigment. In one embodiment, the coating matrix 5, which can also be referred to as binder 5, is quite fine-grained. It comprises SiO2 or is formed from SiO2, and the coating comprises less than 500 ppm Bi2O3 and / or less than 500 ppm ZnO and / or less than 500 ppm B2O3 and / or less than 500 ppm of an alkali oxide, in each case based on the weight. In particular, the binder also comprises 5 SiO2 and less than 500 ppm Bi2O3 and / or less than 500 ppm ZnO and / or less than 500 ppm B2O3 and / or less than 500 ppm of an alkali oxide, in each case by weight.The binder is designed as a sol-gel binder. The coating 11 and / or the binder 5 can also comprise pores 6. However, these are relatively small, so that the coating 11 is or can be microporous in particular and / or has pores with a maximum lateral dimension, for example, a diameter, of 1 µm. These are preferably arranged at the interface between the pane 1 and the coating 11, i.e., on or near the side 102 of the pane 1.

[0122] The coating 11 here also comprises at least one additive, which is preferably in the form of a filler. Preferably, the glass pane 1 in the at least one region, which is arranged here on side 102 of the glass pane 1 and in which the coating 11 is applied, has a flexural strength of between at least 50 MPa and at most 300 MPa, preferably at least 100 MPa and at most 300 MPa, particularly preferably at least 150 MPa.

[0123] In Fig. Figure 4 shows the flexural strength of soda-lime glass panes having a coating produced using a paste according to No. 6 or, as a reference, unprinted (with and without heat treatment).

[0124] The unprinted soda-lime glass is in terms of strength results in Fig.4 on the left (without heat treatment (R1)) and on the right (with heat treatment at 600 °C, i.e., as if fired (R2)) and shows the strength obtained for such unprinted glass panes in this so-called "box plot." Strength values here average slightly above 130 MPa.

[0125] This is different for the embodiment A1 with a 20 µm thick coating 11 on a 3.8 mm thick sheet of soda-lime glass according to one embodiment, namely produced by means of a paste according to No. 6, fired at 600 °C with a heating rate of 30 K / min and a holding time of 4 min, which in Fig.4. Not only is there no reduction in strength compared to the unprinted glass pane (see R1 and R2), but there is actually an increase in strength compared to the unprinted panes. In this case, values of approximately 200 MPa (average) are obtained. The box plots show the results for 13 and 14 samples (comparative examples) and for 7 samples (design example). The results were confirmed by measurements on 17 samples each (not shown).

[0126] The above-described embodiment A1 was incorporated into a composite with another glass pane made of soda-lime glass with a thickness of 2.0 mm and a PVB film with a thickness of 0.7 mm between the two panes. In the area in which the at least one coating completely covers the glass pane, the composite has an L* value, measured in remission without gloss, of 4.1 and a visual transmittance, τ, regardless of which pane faces the source. vis , from < 0.5 to. List of reference symbols 1, 2 glass pane 3 Polymeric layer 10 Laminated, laminated glass pane 11 Coating 101 Side of Disc 1 102 Side of Disc 1 111 grid or dot pattern QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2008 003 804 U1

[0010] US 2013 / 0266781 A1

[0011] US 2009 / 0233082 A2 [0012, 0089] FR 3 084 355 A1

[0013] US 2015 / 0225285 A2

[0014] US 2010 / 0028629 A2 [0016, 0089] EP 3 830 046 A1

[0017] Cited non-patent literature

[0000] ISO / CIE 11664-4 “Colorimetry - Part 4: CIE 1976

[0104]

Claims

[1] Glass pane, in particular partially coated glass pane for a vehicle, comprising a glass comprising SiO2, Na2O and CaO, comprising at least one coating applied in at least one area of at least one side of the glass pane, wherein the at least one coating at least one binder comprising SiO2, which is designed as a sol-gel binder, at least one pigment and preferably comprises at least one additive formed as a filler, and wherein preferably the glass pane in the at least one region which has the applied at least one coating on at least one side of the glass pane has a flexural strength of between at least 50 MPa and at most 300 MPa, preferably at least 100 MPa and at most 300 MPa, particularly preferably at least 150 MPa, characterized bythat the at least one coating comprises less than 500 ppm Bi2O3 and / or less than 500 ppm ZnO and / or less than 500 ppm B2O3 and / or less than 500 ppm of an alkali oxide, in each case based on the weight. [2] A glass pane according to claim 1, wherein the at least one coating comprises only a binder. [3] Glass pane according to one of claims 1 to 2, comprising at least one of the following features: - in at least one partial area or within the entire at least one area of at least one side of the glass pane, a further coating is arranged on the glass pane, preferably a glass-based coating, in particular an enamel coating, - the at least one coating comprises between at least 15% by weight and at most 55% by weight of binder, preferably at least 20% by weight, particularly preferably at least 25% by weight, - the at least one coating comprises between at least 20% by weight and at most 30% by weight of pigment, based on the sum of all pigments comprised by the at least one coating, - the glass of the glass pane has a linear thermal expansion coefficient between 7 * 10- 6 / K and 12 * 10- 6 / K, preferably between 8.5 * 10- 6 / K and 9.5 * 10- 6 / K - the glass of the glass pane comprises at least 71 wt% SiO2 to at most 75 wt% SiO2 and / or at least 12 wt% Na2O to at most 16 wt% Na2O and / or at least 9 wt% CaO to at most 15 wt% CaO, - the glass of the pane contains no B2O3 apart from normal impurities, - the at least one coating has a linear thermal expansion coefficient of at least 3 * 10- 6 / K and at most 10 * 10- 6 / K on, - the glass pane has a thickness of at least 1 mm and at most 12 mm. [4] Glass pane according to one of claims 1 to 3, wherein the at least one coating is microporous and / or has at most pores with a maximum lateral dimension, for example a diameter, of 1 µm. [5] Composite comprising a glass pane according to one of claims 1 to 4 and a further glass pane, wherein preferably the at least one coating is arranged between the glass panes. [6] Composite according to claim 5, wherein the further glass pane is a borosilicate glass pane. [7] A method for producing a glass pane of a glass pane according to one of claims 1 to 4, wherein a paste is applied to at least one side of the glass pane in at least one area and baked so that at least one coating is present in the at least one area. [8] Glass pane according to one of claims 1 to 4, produced or producible by a process according to claim 7.

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