Plate containing glass or glass-ceramic, manufacturing method thereof as well as use thereof

Abstract

To provide a glass plate or glass-ceramic plate having an excellent printed image in a non-contact printing method as well as a manufacturing method thereof.SOLUTION: The object is to provide a glass or plate comprising a glass-ceramic, having two mutually opposite side surfaces and a peripheral edge surface, the flatness of the plate being less than or equal to 0.1% of a lateral dimension, and at least one side has an average surface roughness Rz,average less than 0.5 μm in at least one region, and the standard deviation of the surface roughness σRz is less than 0.1 μm, and further in at least one region on at least one side of the plate, the plate comprising a coating arranged in at least two different sub-areas, the at least two sub-areas being spaced apart from each other by at least 3 cm, the ruggednesses of the coating in both sub-areas differ from each other by at most 10%, the object is solved by the plate.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention generally relates to plates comprising glass or glass ceramic, especially those at least partially covered with a coating, to a method for producing such plates and their use.

[0002] In particular the invention relates to a plate comprising a glass or glass ceramic, especially a lithium aluminium silicate glass or a lithium aluminium silicate glass ceramic, comprising a coating. [Background technology]

[0003] Coated glass or glass-ceramic plates have been known for a long time and have been used for many years, for example as cover plates for cooking devices (also called "cooktops" or "cooking surfaces"). Usually, such plates are provided with at least one coating. For example, plates are known which comprise a body-colored substrate, on the side facing the user (also called "upper side" or "front side") of which a so-called cooking area marking is applied. The printing of logos is also known. Furthermore, plates are also known which comprise a non-body-colored substrate, which is applied with a so-called "underside coating". Depending on the exact configuration of such a plate, different coatings can be combined with one another on different sides of such a plate.

[0004] As the application method, printing method is usually used.Here, the prior art is especially screen printing, which allows high throughput in the production of printed plates.However, the disadvantage is that these plates always have to be printed in the same way, and different printing colors require different method steps.

[0005] As an alternative, inkjet printing is therefore becoming increasingly important: in this way the production of such plates is in principle more flexible: for example smaller series can now be produced.

[0006] However, practice has shown that, for reasons that are as yet unknown, print quality in screen printing is generally better than in inkjet printing.

[0007] EP3346876 A1 describes a method for making a slab with a minimum area of ​​0.7 m for a kitchen block. 2 and a large-area working plate with a substrate diagonal flatness of less than 0.1%. However, the quality of the printing is not discussed here. No mention is made of inkjet printing. The surface roughness of the working plate, which is related to the quality of the inkjet printing, is also not discussed.

[0008] US 2019 / 128534 A2 describes a glass-ceramic plate for kitchen furniture with a small flatness ("flatness") of less than 0.1% on the diagonal. However, again, no mention is made of print quality or inkjet printing. The surface roughness of this work plate, which is related to the quality of the inkjet printing, is also not considered.

[0009] Japanese patent application JP2015 / 176753 A describes a polished surface for a plate used as a cooktop, although the quality of the applied decoration is not discussed here, but rather the focus is on the reflectivity or gloss of the surface and the visual impression of the reverse side printing.

[0010] Said prior art documents do not address the improvement of printed images, especially during non-contact printing, for example with inkjet printing.

[0011] Therefore, there is a need for a glass or glass-ceramic plate having a good printed image in a non-contact printing process, such as inkjet printing, and a method for producing the same. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent Application Publication No. 3346876 [Patent Document 2] US Patent Application Publication No. 2019 / 128534 [Patent Document 3] JP 2015-176753 A Summary of the Invention [Problem to be solved by the invention]

[0013] The object of the present invention is to provide a plate comprising a substrate made of glass or glass ceramic and at least one coating, which at least partially reduces the above-mentioned problems of the prior art. There is also a corresponding need for a method for producing such a plate. [Means for solving the problem]

[0014] Summary of the Invention The problem of the present invention is solved by the subject matter of the independent claims. Preferred and particular embodiments are set out in the dependent claims as well as in the description and drawings of the present disclosure.

[0015] Accordingly, the present disclosure provides a glass or plate, including a glass ceramic, having two mutually opposing side surfaces and a peripheral edge surface, the flatness of the plate being less than or equal to 0.1% of a lateral dimension, and at least one side having an average surface roughness R z,平均 0.5 μm or less, and the standard deviation of said surface roughness σ Rzis less than 0.1 μm, and further comprising a coating disposed in at least two different sub-areas of at least one region on at least one side of the plate, said at least two sub-areas being spaced at least 3 cm from each other, and wherein the ruggedness of the coating in both sub-areas differs from each other by a maximum of 10%.

[0016] Such an arrangement has many advantages.

[0017] Because good flatness and roughness of the plate at the same time allows for good printing quality of the coating, for example in inkjet printing. Very good printing quality is especially shown in the so-called "roughness" of the corresponding coating. Advantageously, the roughness according to one embodiment can be determined according to ISO 24790.

[0018] Roughness is a measure for the image quality of a printed image, describing for example the sharpness of so-called edges. A method for determining roughness is explained in more detail in FIG.

[0019] The flatness of the plate is preferably 0.1% or less of the lateral dimension of the plate, preferably the maximum lateral dimension. For example, according to one embodiment, the corresponding lateral dimension of the plate can be the diagonal of a rectangular plate, where diagonal is generally understood to be the diagonal of the face of the plate, i.e. the diagonal of the main face (or side) of the plate.

[0020] In general, within the scope of this disclosure, a lateral dimension is understood as a measure of the length of a plate. In the scope of this application, a plate is generally understood as an object whose dimensions in two directions of a Cartesian coordinate system are at least an order of magnitude greater than the dimensions in a third spatial direction perpendicular to both first spatial directions. In other words, the thickness of a plate is at least an order of magnitude smaller than its length and width. The length and width of a plate generally identify the main faces (as opposed to the peripheral edge faces, which have only a small proportion of the total surface area of ​​the plate) for rectangular plates. However, a lateral dimension in the sense of this disclosure is in particular the diagonal of the face, which is also referred to as the diagonal within the scope of this application. It is then the maximum lateral dimension of a generally rectangular plate. For the case of non-rectangular plates, for example, the diameter can be substituted for the length, width or diagonal and can be referred to as the corresponding lateral dimension.

[0021] Advantageously, the average surface roughness R z,平均 and the standard deviation of said surface roughness σ Rz is the roughness R at nine points on the plate. z , said points being spaced apart from one another by at least 5 cm, advantageously at least 10 cm, and particularly preferably at least 15 cm, and are determined by determining the arithmetic mean value and the standard deviation from the nine measured values. Particularly preferably, R z is determined in accordance with ISO 4827 by measuring and evaluating the profile of the line with a contact stylus device.

[0022] This flatness is advantageous because it allows homogeneous application and coating in printing, and therefore small and fine structures can also be printed with high quality. But it is also advantageous because it can increase the mounting stability of the plate. It has also been shown that such an arrangement can improve the visibility of the display, because the uniform surface with the smallest possible thickness variation in the plate greatly minimizes the brightness difference in the display. This is particularly advantageous in the case of body-colored materials, where the thickness variation is exponentially expressed through the transmittance characteristic.

[0023] Advantageously, this can be combined with the plate being constructed very smooth, i.e. not very rough and flat on at least one side, but also with both side surfaces being arranged parallel to one another. Thus, according to one embodiment, it can be provided that the side surfaces are preferably arranged parallel to one another. An arrangement is understood as parallel if the normal angles to the side surfaces form an angle of 5° or less with respect to one another, advantageously 2° or less, and particularly preferably 0° within the scope of normal manufacturing and measurement tolerances.

[0024] If a protrusion is formed on one side of the plate, the plane presented by the tip of the protrusion is taken to determine the normal angle.

[0025] The inventor further believes that in this way the processing of the plate in general is also improved: the improved flatness and roughness generally improves the dimensional stability of the plate, but at the same time it is also easier to handle and can for example be better glued.

[0026] According to one embodiment, the plate may have a thickness of 2 mm to 6 mm, which is particularly advantageous for the use of the plate as a cover plate in a cooking device, since in this way a good compromise can be made between a thickness as small as possible, which is advantageous for the cooking start-up behavior, and a sufficient strength of the plate (which is necessarily necessary for such an application and which is greater the greater the plate thickness).

[0027] In general, the flatness and roughness of the plates according to the present disclosure are advantageous for all coating types and methods, however, it is particularly advantageous for inkjet printed coatings.

[0028] Flatness thus determines the minimum distance to the printhead in non-contact inkjet printing. It has been shown that, especially for non-contact printing, the distance between the printhead and the substrate to be printed is very important for a good printed image. Now, if the flatness is more than 0.1%, height differences of up to 600 μm can occur (for example for a diagonal of 60 cm). Thus, the distance between the printhead and the substrate may not be enough for the droplets to actually separate and form completely after leaving the printhead. This can be very important, especially when the distance between the printhead and the substrate is small, for example only 1 mm. It is certainly theoretically possible to correct this by in-line measurement of the plate-printhead distance and by adjusting the height according to the measured distance of the printhead. However, this implies a large mechanical effort. However, this can be avoided by using a smooth and flat substrate as targeted.

[0029] The small flatness allows for a defined spacing of the droplets, which leads to better print control and repeatable droplet placement, which also allows for improved resolution of the printed image.

[0030] It has been found that, especially in the case of inkjet printing, it is important that the distance between the substrate and the print head is precisely maintained; only then is it ensured that the droplet shape or printing color of the printing ink used is optimally formed. It is therefore important to maintain a minimum distance between the print head and the substrate, which can be about 1.5 mm. However, depending on the printing machine, smaller distances, for example 1 mm, are also possible. Below said minimum distance, the droplet morphology cannot be optimally formed, at least approximately spherical.

[0031] On the other hand, if the spacing between the print head and the substrate becomes too large, this can result in deflection of the droplets so that they do not land where they are supposed to on the substrate and / or the formation of so-called satellites, which leads to a decrease in edge sharpness and possibly even holes in the printed image.

[0032] Both of these lead to unstable and blurred print images, respectively. This is particularly difficult when different print images are applied between areas of the substrate, and the print images are printed with different sharpness at different locations on the plate due to lack of flatness and roughness.

[0033] According to one embodiment, the coating comprises a glass flux and / or is formed as an enamel. Preference is given to a coating comprising a glass flux and / or formed as an enamel and comprising at least one pigment. Particularly preferably, the at least one pigment has an equivalent diameter d 50 The pigment particles do not contain pigment particles having a primary particle size of more than 1.0 μm, particularly preferably having an equivalent diameter d 90 It does not contain pigment particles having a primary particle size greater than 2.5 μm as specified.

[0034] Such configurations are particularly advantageous, since coatings containing glass fluxes or coatings formed as enamels are particularly thermally stable and also adhere well to glassy surfaces, such as glass surfaces or glass ceramic surfaces. For example, such coatings can be configured such that the coating or the glass flux contained in the coating and the material of the substrate are intimately bonded during firing, due to the formation of so-called "molten reaction zones". In this way, such coatings can also be configured so that they can be used as upper decorations, for example on so-called cooking surfaces. Such upper decorations, which are used, for example, for printing logos or for marking cooking areas, must also withstand partly very harsh cleaning conditions (with so-called glass scrapers) as well as conditions of use (for example wear due to the movement of cooking utensils, partly under thermal load).

[0035] Within the scope of the present disclosure, a coating comprising a glass flux is understood to mean a coating having at least one glassy component, for example produced from a paste comprising glass powder. Within the scope of the present disclosure, such coatings are also referred to as "enamels", especially when the glass flux is at least partially melted, especially during firing.

[0036] In principle, it is possible for the coating arranged on the substrate to only comprise a glass flux. In this case, it can also be understood or referred to as a "glaze". In general, however, it is possible and in fact preferred for the coating to comprise at least one pigment in addition to the glass flux or to be formed as an enamel comprising at least one pigment. In this way, the visibility of the marking is increased, which can increase, for example, the safety of the user of a cooking device equipped with such a plate. On the other hand, depending on the type of pigment, the mechanical resistance of the coating can also be increased, for example, if particularly wear-resistant pigments are used.

[0037] Suitable glass fluxes may have a composition based on, for example, SiO2 and B2O3, or based on Bi2O3 and SiO2, where "based on" means that these components make up at least 50% by weight of the composition.

[0038] Further examples for glass fluxes based on SiO2 and B2O3 are given below.

[0039] Two examples of suitable glass fluxes based on Bi2O3 and SiO2 are given in the table below.

[0040] [Table 1]

[0041] By pigment is meant here a colorant comprising solid particles. In particular, pigments can be configured according to the present disclosure as ceramic colorants. By "ceramic" is meant within the scope of the present disclosure an inorganic, non-metallic substance. This is advantageous, since ceramic colorants have high temperature resistance, which is essential in particular for the applications addressed here.

[0042] It may furthermore be advantageous if the primary particle size of the pigment particles, i.e. the particles contained in the colorant, is correspondingly limited as indicated above. This is advantageous for coating by inkjet printing without nozzle clogging. Furthermore, the use of fine pigment particles also simplifies the printing of microstructures and can therefore be used here with particular advantage, since due to the high smoothness and flatness of the plate according to the present disclosure, such microstructures can now be particularly well represented.

[0043] In particular, it is also possible for the plate to be formed as a double-sided smooth plate, which is understood in particular that none of the sides of the plate are formed with protrusions. A double-sided smooth plate can be particularly advantageous if a high-resolution display is to be arranged under the plate. In particular, the low roughness and low roughness of the plate are particularly well suited for such a configuration and can therefore also be well combined with a high-resolution display.

[0044] Alternatively, in particular when a particularly high strength of the plate is necessary or advantageous, it is also possible for one side of the plate to be smooth and the opposite side to be formed with protrusions, in which case the coating is arranged on the smooth side of the plate. In this case, the side of the plate with the protrusions is formed as the underside. The structure with protrusions can at least partially reduce possible mechanical damage of the glass or glass ceramic material with respect to its effect on the strength of the plate. This also makes the plate easier to handle.

[0045] According to one embodiment, the plate comprises a glass ceramic, said glass ceramic advantageously having at least one of the following characteristics: The glass ceramic is body-colored; The glass ceramic does not include a surface region that is vitrified on at least one side. has.

[0046] The construction of the plate in a form comprising glass ceramics is particularly advantageous, since glass ceramics, in particular so-called lithium aluminum silicate glass ceramics, have high strength and a low coefficient of thermal expansion and therefore sufficient temperature difference resistance so that they can be used particularly advantageously in cooking appliances.

[0047] Suitable glass-ceramics can be produced using a variety of fining agents, thus, for example, glass-ceramics refined with As2O3, Sb2O3, SnO2, CeO2 or combinations thereof are suitable.

[0048] For example, glass ceramics having the following composition in wt. % based on the oxides are suitable: [Table 2]

[0049] Such glass ceramics may also contain up to 2% by weight of further components, especially in the form of impurities.

[0050] It can be advantageous for the glass ceramic to be body-colored, since in this way the glass ceramic is sufficiently opaque by itself to mask structural elements of the cooking device arranged behind the plate, in particular without the mandatory need for a masking layer on the side facing the user or on the opposite side.

[0051] According to a further embodiment, the plate comprises a glass ceramic, which does not comprise a surface region formed in a vitrified state on at least one side. In this way, it has been shown that a particularly smooth and only slightly rough surface on at least one side can be achieved. This can be achieved in particular when at least one side of the plate is ground and polished.

[0052] According to a further preferred embodiment of the plate, it has an improved blurring of the region around the characters. This value describes the number of defects or satellites of the ink / printing ink droplets around the deposited droplet or printed image. This value is improved in the case of the plate according to the present disclosure, especially since the plate has a lower roughness or a higher smoothness. The droplets can thus be deposited uniformly in a contactless manner and the deflection of the droplets will be significantly less.

[0053] The present disclosure also relates to a method for producing a plate comprising glass or glass ceramic, in particular a plate according to an embodiment of the present disclosure, said method comprising the following steps: providing a plate comprising glass or glass ceramic, in particular said plate may comprise lithium aluminium silicate glass or lithium aluminium silicate glass ceramic, preferably said plate has a thickness of 2 to 6 mm, said plate being formed in particular in a flat form, i.e. having two mutually facing, preferably parallel, side surfaces and a peripheral edge surface, grinding at least one side of said plate; a polishing step of at least one side of said plate, advantageously the previously ground side, printing on at least one side of the plate, preferably on the previously ground and / or polished side, in at least two different partial areas of at least one area of ​​at least one side of the plate, in which a coating is arranged in the at least two different partial areas, the at least two partial areas being spaced apart from one another by at least 3 cm, advantageously by at least 9 cm and particularly preferably by at least 15 cm, advantageously the printing can be carried out using a non-contact printing method, advantageously by inkjet printing, baking the coating Includes.

[0054] The baking can be carried out in a number of known ways. For example, the baking can be carried out in an oven, in particular an oven for thermal strengthening of glass or for ceramification of glass ceramics. Here, in particular, a tunnel oven can be used. The baking temperature can be more than 650°C, more than 700°C or even more than 750°C.

[0055] In addition, however, optical methods can also be used, such as laser radiation, in particular using a CO2 laser, a flash lamp ("photonic flash sintering") or short wave infrared (KIR radiation).

[0056] The method according to the embodiment can furthermore for example be carried out in such a way that, for example, so-called green glass is printed, which is then converted into glass ceramic during firing (so-called first firing).

[0057] However, it may be preferable that the glass ceramic is already printed. It may already be ground and polished before ceramming. However, it may also be possible and preferable to carry out the grinding and polishing steps only after conversion to glass ceramic. This may be advantageous, in particular, since it allows a high dimensional stability of the plate. Since ceramming necessarily involves size changes (e.g. shrinkage) in the glass ceramic, the high surface quality with favorable smoothness of the plate may be reduced by ceramming, since the temperatures required therein are accompanied by size changes (e.g. shrinkage) in the glass ceramic. It is also possible that the surface roughness increases during ceramming due to the adaptation of oxidizing impurities and / or softened glass bodies to the substrate plate. This can be avoided by adjusting the good surface properties of the plate by grinding and polishing only after ceramming. In this case, the coating is baked in a so-called second firing, whereby lower temperatures than in the first firing are also possible.

[0058] According to one embodiment of the method, the coating comprises a glass flux and / or is formed as an enamel. Preferably, the coating comprises a glass flux and / or is formed as an enamel and further comprises at least one pigment, where particularly preferably the at least one pigment has an equivalent diameter d 50 The pigment particles do not contain pigment particles having a primary particle size of more than 1.0 μm, particularly preferably having an equivalent diameter d 90 It does not contain pigment particles having a primary particle size greater than 2.5 μm as specified.

[0059] According to one embodiment, the plate comprises glass, in particular green glass, and the baking of the coating is carried out during a ceramming stage, in which the glass is converted into a glass ceramic.

[0060] According to a further preferred embodiment, said plate comprises a glass ceramic and the baking of the coating is carried out in a second firing.

[0061] The present disclosure also relates to a plate comprising a glass or glass ceramic, advantageously a plate comprising a glass or glass ceramic according to an embodiment of the present disclosure, a plate comprising a glass or glass ceramic produced or producible in a method according to an embodiment.

[0062] The present disclosure also relates to the use of the plate according to the embodiment and / or manufactured by the method according to the embodiment as a cooking surface. By cooking surface is understood within the scope of the present disclosure a plate used as a cover plate in a cooking device. Such a cooking surface may also be synonymously referred to as a cooking plate. By cooking device is understood within the scope of the present disclosure an apparatus for cooking food by means of heat, in particular a so-called cooktop on which a cooking utensil is placed. [Brief description of the drawings]

[0063] [Figure 1] FIG. 13 is a schematic diagram for explaining roughness. [Diagram 2] FIG. 1 is a schematic, not-to-scale, top view of a plate according to one embodiment. [Diagram 3] FIG. 2 is a schematic, not-to-scale, side view of a plate according to an embodiment. [Figure 4] FIG. 2 is a schematic, not-to-scale, side view of a plate according to an embodiment. EXAMPLES

[0064] The present invention will be further described below with reference to examples and comparative examples.

[0065] Example 1 Body: Colored, ceramicized glass-ceramic material (600 x 600 mm2 ) was subjected to a two-stage removal process.

[0066] The first step was a coarse abrasive removal using a rotating pad (d = 15 cm) saturated with a CeO2 suspension. 50 The values ​​were between 2 and 2.5 μm. The process was carried out until the flatness of the plate was less than 0.1% of the plate diagonal (i.e. less than 600 μm in this case).

[0067] After the target value of flatness is reached, the roughness R is reduced by localized heating using a CO2 laser with a spatial wavelength range of 100 μm. Z,平均 The initial roughness was reduced until it was less than 0.5 microns.

[0068] The polished surface was then printed with a post-fireable flux using an inkjet printer. The printing ink was then baked in a baking process at a maximum temperature of 750°C for 45 minutes.

[0069] The print or printed image then had very little deviation in print quality across the plate (raggedness 22.26 μm for a line with width 300 μm).

[0070] The composition of the plates is given in the table below: [Table 3]

[0071] The composition of the glass flux is given in the table below: [Table 4]

[0072] The printing ink or inks used for printing were composed as follows: Glass flux 1 2.98% by mass Black pigment CuCr2O4 1.05% by mass White pigment TiO2 0.87% by mass Dipropylene glycol methyl ether 62.71% by mass Additive 1 2.09% by mass Additive 2 0.30% by weight.

[0073] Additive 1 is poly(oxy-1,2-ethanediyl), α-methyl-ω-phosphate. Additive 2 is polyether modified polymethylsiloxane.

[0074] Using this printing ink, the effective linear thermal expansion coefficient α 20-300,有効 9.15×10 -6 / K is achieved.

[0075] Example 2: Body: Colored, ceramicized glass-ceramic material (600 x 600 mm 2 ) was subjected to a two-stage removal process.

[0076] The first step was a coarse abrasive removal using a rotating pad (d = 15 cm) saturated with a CeO2 suspension. 50 The values ​​were between 2 and 2.5 μm. The process was carried out until the flatness of the plate was less than 0.1% of the plate diagonal (i.e. less than 600 μm in this case).

[0077] After the target flatness was reached, ion beam figuring (IBF) was used to measure the roughness R Z,平均 Further material was removed until the thickness was less than 0.5 μm.

[0078] The polished surface was then printed with a post-fireable flux using an inkjet printer. The printing ink was then baked in a baking process at a maximum temperature of 750°C for 45 minutes.

[0079] The print or printed image then had very little deviation in print quality across the plate (raggedness 29.04 μm for a line with a width of 300 μm).

[0080] The composition of the glass-ceramic material used is given in the table below: [Table 5]

[0081] The composition of the glass flux used is given in the table below: [Table 6]

[0082] The printing ink / inks used were composed as follows: Glass flux 1 2.98% by mass Black pigment CuCr2O4 1.05% by mass White pigment TiO2 0.87% by mass Dipropylene glycol methyl ether 62.71% by mass Additive 1 2.09% by mass Additive 2 0.30% by weight.

[0083] Additive 1 is poly(oxy-1,2-ethanediyl), α-methyl-ω-phosphate. Additive 2 is polyether-modified polymethylsiloxane. Using this, the resulting effective linear thermal expansion coefficient α for the glass particles and pigment particles contained in the printing ink was 20-300,有効 9.15×10 -6 / K is achieved.

[0084] Example 3: Green glass material (600 x 600 mm 2 ) was subjected to a two-stage removal process.

[0085] The first step was a coarse abrasive removal using a rotating pad (d = 15 cm) saturated with a CeO2 suspension. 50 The values ​​were between 2 and 2.5 μm. The process was carried out until the flatness of the plate was less than 0.1% of the plate diagonal (i.e. less than 600 μm in this case).

[0086] After the target value of flatness is reached, the roughness R is reduced by localized heating using a CO2 laser with a spatial wavelength range of 100 μm. Z,平均 The initial roughness was reduced until it was less than 0.5 microns.

[0087] The polished surface was then printed with a post-fireable flux using an inkjet printer. The printing ink was then baked in a baking process at a maximum temperature of 750°C for 45 minutes.

[0088] The print or printed image then had very little deviation in print quality across the plate (raggedness 23.02 μm for a line with width 300 μm).

[0089] After printing, the printed substrate was subjected to a ceramming process to convert it into a glass-ceramic.

[0090] Comparative Example 1 In the case of Comparative Example 1, the flatness is good but the roughness is poor, i.e. high. This leads to a large change in the roughness of the printed image, as shown below.

[0091] Body: Colored, ceramicized glass-ceramic material (600 x 600 mm 2 ) was subjected to only one-step removal process.

[0092] This step consisted of a coarse abrasive removal using a rotating pad (d = 15 cm) saturated with a CeO2 suspension. 50 The values ​​were between 2 and 2.5 μm. The process was carried out until the flatness of the plate was less than 0.1% of the plate diagonal (i.e. less than 600 μm in this case).

[0093] After the flatness target was reached, no further polishing was performed. Z,平均 was 0.7 μm.

[0094] The polished surface was then printed with a post-fireable flux using an inkjet printer. The printing ink was then baked in a baking process at a maximum temperature of 750°C for 45 minutes.

[0095] The print or printed image then had deviations in print quality across the plate (raggedness 45.3 μm for a line with width 300 μm).

[0096] The composition of the plates is given in the table below: [Table 7]

[0097] The composition of the glass flux is given in the table below: [Table 8]

[0098] The printing ink or inks used for printing were composed as follows: Glass flux 1 2.98% by mass Black pigment CuCr2O4 1.05% by mass White pigment TiO2 0.87% by mass Dipropylene glycol methyl ether 62.71% by mass Additive 1 2.09% by mass Additive 2 0.30% by weight.

[0099] Additive 1 is poly(oxy-1,2-ethanediyl), α-methyl-ω-phosphate. Additive 2 is polyether modified polymethylsiloxane.

[0100] Using this printing ink, the effective linear thermal expansion coefficient α 20-300,有効 9.15×10 -6 / K is achieved.

[0101] Comparative Example 2 In the case of Comparative Example 2, the flatness is poor, but the plate roughness is good, i.e. small, which leads to poor roughness of the printed image, as shown below.

[0102] Body: Colored, ceramicized glass-ceramic material (600 x 600 mm 2 ) was subjected to a one-step removal process.

[0103] No grinding process was performed to achieve flatness, which was 789 μm.

[0104] The plate is locally heated using a CO2 laser with a spatial wavelength range of 100 μm to obtain a roughness R Z,平均 The initial roughness was reduced until it was less than 0.5 microns.

[0105] The polished surface was printed with a second-fireable flux using an inkjet. Due to the poor flatness, the printhead spacing had to be changed during printing to avoid damaging the printhead. This caused the droplets generated by the printhead to have different path lengths relative to the substrate. The printed ink was baked in a baking process with a maximum temperature of 750°C for 45 minutes.

[0106] The print or printed image then had a deviation in print quality across the plate (raggedness 62.8 μm for a line with width 300 μm).

[0107] The composition of the plates is given in the table below: [Table 9]

[0108] The composition of the glass flux is given in the table below: [Table 10]

[0109] The printing ink or inks used for printing were composed as follows: Glass flux 1 2.98% by mass Black pigment CuCr2O4 1.05% by mass White pigment TiO2 0.87% by mass Dipropylene glycol methyl ether 62.71% by mass Additive 1 2.09% by mass Additive 2 0.30% by weight.

[0110] Additive 1 is poly(oxy-1,2-ethanediyl), α-methyl-ω-phosphate. Additive 2 is polyether modified polymethylsiloxane.

[0111] Using this printing ink, the effective linear thermal expansion coefficient α 20-300,有効 9.15×10 -6 / K is achieved.

[0112] Description of the drawings The invention is further explained below with the aid of the drawings.

[0113] FIG. 1 is a schematic diagram for explaining roughness.

[0114] FIG. 2 is a schematic, not-to-scale, top view of a plate according to one embodiment.

[0115] 3 and 4 are respective side views of a plate according to the embodiment, which are schematic and not to scale.

[0116] In FIG. 1, three schematic diagrams a), b) and c) are used to explain rajedness and the principles that identify it.

[0117] Figures 1a) and 1b) show two printed images, of which the one shown in 1a) has only low raggedness and the one shown in 1b) has high raggedness. "Raggedness" literally means "splitting" and can be understood as a measure of the quality of a printed image, in particular of the sharpness of its edges. High raggedness means low edge sharpness and vice versa.

[0118] In Fig. 1a) and Fig. 1b) we see an enlargement of two "line prints". In Fig. 1b), which has a large "raggedness", partly individual droplets are still clearly discernible, since they were not sufficiently bled for a homogeneous image. Edge sharpness is only slightly formed, and partly holes in the printed image are discernible.

[0119] In contrast, the image in FIG. 1a) has a clearly improved edge sharpness, which also corresponds to a smaller roughness.

[0120] Fig. 1c) shows a schematic enlarged printed image of the "line". First, we select a region that is prominent here with respect to line width 1, and fit both edges of said line with straight lines, respectively. These two straight lines, which represent the boundaries of the "ideal line", are shown in the diagram of Fig. 1c) as schematic white lines on the black printed image.

[0121] Based on both these lines the standard deviation of the actual border of the printed image on both sides of the ideal line is then determined, as shown diagrammatically in position 2 of FIG. 1c).

[0122] Roughness is the arithmetic mean of the standard deviations on one side, here the "left", and on the other side, here the "right".

[0123] Advantageously, the plate according to one embodiment is configured such that the roughness in both partial regions differs from one another by at most 10%. Advantageously, the ratio of the roughness R1 in one partial region to the roughness R2 in the second partial region, i.e. the R1 / R2 value, is 0.5 to 2, advantageously 0.75 to 1.5, particularly preferably 0.9 to 1.1.

[0124] FIG. 2 is a schematic and not to scale view of a plate 3 according to one embodiment. The plate 3 comprises a glass or a glass ceramic. The glass can in particular be a lithium aluminum silicate glass, and the glass ceramic can be a lithium aluminum silicate glass ceramic. Advantageously, the plate 3 has a thickness of 2 to 6 mm. The plate has two mutually opposite, advantageously parallel, side surfaces (only the side surface 31 is visible here), as well as a peripheral edge surface 33. The flatness of the plate 3 is less than or equal to 0.1% of a lateral dimension 5, which here is for example the diagonal of the rectangularly configured plate 3. Advantageously, the lateral dimension 5 considered is the maximum lateral dimension of the plate 3, which can for example be the diameter of a circular plate 3.

[0125] On at least one side of the plate 3, here side 31, this has at least one region, here region 311, an average surface roughness R z,平均 0.5 μm or less, and the standard deviation of said surface roughness σ Rz is less than 0.1 μm. Advantageously, R z,平均 and the standard deviation of said surface roughness σ Rz is the roughness R at nine points on plate 3. z , said points being spaced apart from one another by at least 5 cm, advantageously at least 10 cm, and particularly preferably at least 15 cm, and are determined by determining the arithmetic mean value and the standard deviation from the nine measured values, and particularly preferably R z is determined by measuring and evaluating the profile of the line with a contact stylus in accordance with ISO 4827.

[0126] Roughness R z Also referred to as the roughness depth, it describes the maximum height difference along the centerline in a given measurement area.

[0127] Furthermore, the plate 3 comprises a coating 4 which is arranged in at least two different partial areas 3101, 3102 of an area 311 of at least one side 31 of the plate 3. Here, for example, the coating 4 is formed as a cooking area marking, i.e. in the form of four rings which are applied to the side 31. The area 311 comprises, for example, one of these cooking area markings.

[0128] In principle, it is possible for the area 311 to include the entire surface of the side 31. In particular, it is also possible for the partial areas 3101 and 3102 of the area 311 to relate to the marking of different cooking areas.

[0129] The ruggedness of the coating 4 in both partial regions 3101 and 3102 differs from one another by a maximum of 10%, said ruggedness being advantageously specified in accordance with ISO 24790.

[0130] Advantageously, according to one embodiment, the coating 4 may be an inkjet printed coating.

[0131] 3 shows a schematic and not to scale side or cross-sectional view of a plate 3 according to one embodiment. The plate 3 comprises a glass or a glass ceramic, in particular a lithium-aluminum silicate glass or a lithium-aluminum silicate glass ceramic, and has a thickness d which is preferably between 2 mm and 6 mm. The thickness of the plate 3 is generally understood to be the distance between the two side surfaces 31, 32 of the plate 3. The two side surfaces 31, 32 of the plate 3 face each other and are preferably arranged parallel to each other within the measurement accuracy as shown in the diagram of FIG. 3.

[0132] An arrangement is understood as parallel if the normal angles to the side surfaces 31, 32 form an angle of less than 5° with respect to one another, advantageously less than 2° and very particularly preferably 0° within the bounds of normal manufacturing and measurement tolerances.

[0133] If one side 31, 32 of the plate 3 is formed with protrusions, the plane provided by the tips of the protrusions is taken to determine the normal angle, which is shown more diagrammatically below with the aid of FIG.

[0134] Also shown in FIG. 3 is a peripheral edge surface 33 of the plate 3 .

[0135] At least the side 31, in particular on which the coating 4 is arranged, has a small average roughness R of less than 0.5 μm in at least one region 311. z,平均 and the standard deviation of the surface roughness σ Rz is configured to be less than 0.1 μm.

[0136] The plate 3 further comprises a coating 4 arranged in at least two different partial regions 3101, 3102 of the at least one region 311. The at least two partial regions 3101, 3102 are spaced apart from one another by at least 3 cm, advantageously by at least 9 cm and particularly preferably by at least 15 cm, and the ruggedness of the coating 4 in both partial regions 3101, 3102 differs from one another by a maximum of 10%, advantageously said ruggedness being specified in accordance with ISO 24790.

[0137] It may be intended that side 32 is also formed as a very smooth and / or very even surface. However, it may also be possible and in fact preferred that only the side facing the user or operator during operation of the device, for example a so-called cooktop, here side 31, has a particularly good roughness and flatness. In particular, it may be intended that the region 311 of side 31 of plate 3 includes the entire surface of side 31, i.e. in other words the entire side 31 is formed as a very smooth and flat surface. In this way, it is thus possible to achieve a uniformly good printed image over the entire side 31, in particular also in non-contact printing methods, for example inkjet printing.

[0138] If the side 32 of the plate 3 opposite the side 31 configured as the upper side is not configured as smooth and flat as the side 31, it can be provided that said side 32 is formed with protrusions, for example. Advantageously, this can be combined, for example, with the plate 3 comprising a colored glass ceramic, since in this case the protrusions are not visible in an undesirable way due to the inherent coloring of the glass ceramic contained in the plate 3. Such an arrangement can be advantageous in particular if a particularly good strength of the plate 3 is desired.

[0139] Fig. 4 shows a schematic and not to scale view of a side view of a plate 3 according to one embodiment. The plate 3 has a side 31 which has a very good flatness and a very small average roughness depth, i.e. is formed very smoothly. The side 31 is formed as the upper side, i.e. is defined as facing towards the user during the operational use of the device, for which the plate 3 is used as a cover plate (for example a so-called cooktop). On the side 31 of the plate 3, in two partial areas 3101, 3102 of the area 311, which have at least good flatness and smoothness, respectively, a coating 4 is arranged, which can be applied in particular by a non-contact printing method, for example inkjet printing. For example in general, and without being limited to the example of the plate 3 specifically shown here, the coating 4 can be formed both as a marking of the cooking area and also as a logo. In particular, the coating 4 can be formed as a coating based on a glass flux or can contain a glass flux or can be formed as an enamel, and it can furthermore be possible, and in fact it can be preferred, that the coating 4 is formed as a coating based on a glass flux (or contains a glass flux) or is formed as an enamel and further comprises at least one pigment, in particular a ceramic pigment. The at least one pigment preferably has an equivalent diameter d 50 The pigment particles do not contain pigment particles having a primary particle size of more than 1.0 μm, particularly preferably having an equivalent diameter d 90 It does not contain pigment particles having a primary particle size greater than 2.5 μm as specified.

[0140] The plate 3 is now formed in such a way that the side 32 opposite to the side 31 of the plate is formed with a protrusion, in the schematic and not to scale view of Fig. 4, whereby both opposite sides 31, 32 are now formed parallel to each other. To specify this, the normal angles on both sides 31, 32, as shown diagrammatically in Fig. 4, i.e. the angle n 31 and n 32In the case of the side 32 having a protrusion, a surface 32a shown as a dashed line in the schematic cross-sectional view of FIG. 4 is identified, which is given by the tip of the protrusion. The normal angle to this surface is then the normal angle n of the side 32. 32 It is adopted as.

[0141] As can be seen from the schematic diagram in FIG. 4, normals onto both sides 31, 32 are parallel to each other within the measurement accuracy range, so that sides 31, 32 are also formed parallel to each other within the measurement accuracy range. [Explanation of symbols]

[0142] 1 Line width 2. Misalignment of printed image from edge 3 Plate 31, 32 Plate side 32a: A plate or side 32 having a protrusion 33 Peripheral edge faces 311 Side 31 Area 3101, 3102, subarea of ​​311 4. Coating 5.3 Horizontal dimensions n 31 , n 32 Normal angles on 31 and 32

Claims

1. A plate comprising glass or glass ceramic, particularly lithium aluminum silicate glass or lithium aluminum silicate glass ceramic, having a thickness of 2 mm to 6 mm, and having two mutually opposing, preferably parallel, side surfaces and a peripheral edge surface, The flatness of the plate is 0.1% or less of the lateral dimension of the plate, for example, the diagonal, and At least one side has an average surface roughness R in at least one region. z,平均 Having a surface roughness of less than 0.5 μm, and the standard deviation of the surface roughness σ Rz It is less than 0.1 μm, To have an advantage, R z,平均 and the standard deviation σ of the surface roughness Rz The roughness R z The θ is measured at nine points on the plate, each of which is spaced at least 5 cm, preferably at least 10 cm, and particularly preferably at least 15 cm apart from one another, and is determined by determining the arithmetic mean and standard deviation from these nine measurements, and particularly preferably R z This is identified by measuring and evaluating the line profile using a contact stylus device in accordance with ISO 4827. The plate further includes a coating disposed in at least two different sub-regions of at least one region on at least one side of the plate, wherein the at least two sub-regions are spaced apart from each other by at least 3 cm, preferably at least 9 cm, and particularly preferably at least 15 cm, and the raggedness of the coating differs from each other by up to 10% in both sub-regions, preferably the raggedness being specified in accordance with ISO 24790.

2. The plate according to claim 1, wherein the coating is an inkjet-printed coating.

3. The coating comprises a glass flux and / or is formed as an enamel, preferably a coating comprising a glass flux and / or formed as an enamel and comprising at least one pigment, particularly preferably the at least one pigment having an equivalent diameter of d 50 It does not contain pigment particles having a primary particle size greater than 1.0 μm, which is specified as a value, and is particularly preferably of an equivalent diameter d 90 The plate according to claim 1, which does not contain pigment particles having a primary particle size greater than 2.5 μm, which is specified as a value.

4. The plate is formed as a smooth plate on both sides, and in particular, neither side of the plate is formed with protrusions, or The plate is formed such that one side is smooth and the opposite side has a projection, and the coating is placed on the smooth side of the plate. The plate according to claim 1.

5. The plate comprises a glass ceramic and, advantageously, has at least one of the following features: - The glass ceramic is formed with the main body colored. - The glass ceramic does not include a surface region formed as glass on at least one side. A plate according to claim 1, having the following features.

6. A method for manufacturing a plate containing glass or glass ceramic, preferably the plate according to any one of claims 1 to 5, comprising the following steps: - A step of preparing a plate comprising glass or glass ceramic, particularly lithium aluminum silicate glass or lithium aluminum silicate glass ceramic, having a thickness of 2 to 6 mm, and having two mutually opposing, preferably parallel, side surfaces and a peripheral edge surface. - The step of grinding at least one side of the plate, - The step of polishing at least one side of the plate, - A step of printing on at least one side of the plate in at least two different sub-regions of at least one region on at least one side of the plate, wherein the coating is placed in the at least two different sub-regions, the at least two sub-regions are spaced apart from each other by at least 3 cm, preferably at least 9 cm, and particularly preferably at least 15 cm, and the printing is preferably done using a non-contact printing method, preferably using inkjet printing. - The step of baking the aforementioned coating. The method, including the method described above.

7. At least one of the following characteristics: ・ The coating contains a glass flux and / or is formed as an enamel, preferably a coating containing a glass flux and / or formed as an enamel and containing at least one pigment, particularly preferably the at least one pigment does not contain pigment particles having a primary particle size greater than 1.0 μm specified as the d 50 value, especially particularly preferably does not contain pigment particles having a primary particle size greater than 2.5 μm specified as the d 90 value, - The plate includes glass, particularly green glass, and the coating is baked during the ceramicization step, which converts the glass into glass ceramic. The plate contains glass ceramic, and the coating is baked in a secondary firing. The method according to claim 6, characterized by the above.

8. A plate comprising glass or glass ceramic, manufactured or manufacturable according to the method of claim 6.

9. Use of the plate described in claim 1 as a cooking surface.

10. Use of a plate manufactured according to the method of Claim 6 as a cooking surface.

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