CN117980280A

CN117980280A - Method for manufacturing a glass article having a surface that can be easily cleaned and article that can be manufactured according to the method

Info

Publication number: CN117980280A
Application number: CN202280060364.1A
Authority: CN
Inventors: Y·格努吕; E·鲁迪吉尔-沃伊特; S·M·布雷尼格; G·格罗斯
Original assignee: Schott AG
Current assignee: Schott AG
Priority date: 2021-09-07
Filing date: 2022-09-06
Publication date: 2024-05-03
Also published as: DE102021123142A1; WO2023036773A1

Abstract

It is an object of the present invention to provide a coating for glass articles, such as cooktops, which further reduces cleaning work and is stable even after prolonged high temperature action, such as in the range of 250-300 ℃. To this end, a method for producing a glass article with a surface that can be cleaned simply is proposed, wherein-the glass article (1) is provided and transferred into a vacuum chamber (5), and-a vacuum with a pressure of at most 300mbar is generated in the vacuum chamber (5), -silane is deposited on the surface (2) of the glass article (1) by evaporation of the silane in vacuum, wherein-the silane comprises linear silane molecules (7) with at least doubly chlorinated silicon atoms at one end, and wherein-after deposition, the end of the silane molecules is bonded to the surface (2) of the glass article, and wherein-the other end of the silane molecules is formed by chains with at least four perfluorinated atoms, such that the chains are directed outwards after bonding to the surface (2) of the glass article (1), and wherein the silane molecules (7) form a coating (9) in the form of a monolayer after vapor deposition.

Description

Method for manufacturing a glass article having a surface that can be easily cleaned and article that can be manufactured according to the method

Technical Field

The present invention relates generally to glass articles, particularly glass articles for use in the household or glazing field. Glass articles herein also include articles made from glass-ceramics. The invention relates in particular to glass articles provided with a coating that prevents or reduces the attachment of contaminants and thereby simplifies cleaning of the articles.

Background

Coatings that improve cleanability are known in the art. The surface so treated is also referred to as an "easy to clean" or ETC surface. Superhydrophobic and superhydrophilic coatings are generally used for this purpose. Whether a surface is hydrophobic or hydrophilic is classified according to the contact angle of water. In the superhydrophobic surface, water on the surface is formed into almost spherical water droplets due to a large contact angle. The water droplets roll over the surface and at the same time carry away the contaminants. In hydrophilic coatings, water diffuses into the film, which wets and entrains contaminants.

However, both mechanical mechanisms work well at this time only if the contaminants are not adhered or firmly attached to the surface and other mechanisms such as high temperature or mechanical cleaning are not used. The loose dust can thus be easily removed from the respectively associated surfaces by means of rainwater. Likewise, food products (e.g., ketchup) can be easily removed from household products having ETC coatings if they are not burned.

However, for glassware such as cooktops that are subjected to higher temperatures or mechanical loads, such as by scrubbing during cleaning, the effect of "easy-to-clean" can be degraded by the contact angle. The hydrophilic or hydrophobic character of the surface may be reduced or even lost due to the high temperature. The ETC coating may be rubbed off due to mechanical action. It is possible that the ETC coating reacts chemically and is subsequently removed by a cleaning agent. Eventually contaminants, such as food residues, will adhere so strongly that even ETC coatings cannot be easily removed. This situation is also exacerbated when the coating is not uniform and therefore has different contact angles depending on location.

Disclosure of Invention

It is therefore an object of the present invention to provide a coating for glass articles, such as stove tops, which further reduces cleaning work and is stable even after prolonged high temperature action, such as after 250-300 ℃. Furthermore, the coating should be very uniform and as visually insignificant as possible.

This object is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are set forth in the respective dependent claims.

The invention therefore proposes a method for producing a glass product with a surface that can be cleaned easily, wherein

-Providing and transferring the glass article into a vacuum chamber, and

-Generating a vacuum with a pressure of 300mbar maximum in a vacuum chamber, and

-Evaporating the silane in vacuo to deposit the silane on the surface of the glass article, wherein-the silane comprises linear silane molecules having at least bi-chlorinated silicon atoms at one end, and wherein-after deposition, the end of the silane molecules is bonded to the surface of the glass article, and wherein-the other end of the silane molecules is formed from chains having at least four perfluorinated atoms, in particular carbon atoms, such that the chains point outwards after bonding to the surface of the glass article, and wherein the silane molecules form a coating in the form of a monolayer after vapor deposition.

Deposition in vacuo has proven to be very effective with selected molecules for easy removal of baked or burnt foods, by which a self-organized monolayer of silane molecules is formed. It has also been found that this layer is very durable and can withstand long-term temperature loads and mechanical influences.

By means of which a glass article can be produced, which glass article has a surface on which one end of a linear silane molecule is attached, which end is formed by at least di-chlorinated silicon atoms, wherein the silane molecule forms a coating on the surface in the form of a monolayer, and wherein the other end of the silane molecule is formed by chains with at least tetra-perfluorinated atoms, in particular carbon atoms, such that the chains in the monolayer are directed outwards. The carbon atoms of the chain may also be replaced, if necessary, in whole or in part by silicon atoms.

In a particularly preferred embodiment, the glass article is configured in the form of a disk or plate. However, such a disk-shaped product can also be embodied as curved.

A glass article configured according to the present invention is suitable, for example, as a glass substrate for a cooktop. Other applications are also possible. The glazing is therefore based on good temperature resistance and is particularly suitable also as glazing for oven doors.

Drawings

The invention is described in more detail below and in accordance with the accompanying drawings. Like reference numerals designate identical or corresponding elements throughout the several views.

Fig. 1 schematically shows an apparatus for performing the method.

Fig. 2 schematically illustrates a coated glass article.

Fig. 3 schematically illustrates a coated glass article according to an embodiment.

Fig. 4 to 8 show TOF-SIMS spectra of two examples and two comparative examples.

Fig. 9 shows a measurement of the coating thickness.

Fig. 10 shows a bar graph of contact angles of various coatings that can be cleaned easily before and after temperature treatment.

Fig. 11 shows measurements of the area occupied after cleaning after baking a food product for various coatings that can be cleaned simply.

Fig. 12 is a photographic image of the surface of a glass article after baking the food and cleaning.

Fig. 13 shows a cooktop surface with glass articles.

Detailed Description

An apparatus 10 for performing a method according to the present disclosure is schematically shown in fig. 1. The apparatus 10 comprises a vacuum chamber 5 which can be evacuated by means of a vacuum pump 50. One or more glass articles 1 can be arranged in the vacuum chamber 5. A reservoir 6 comprising silane or silane molecules 7 is also provided in the vacuum chamber 5. For coating, the vacuum chamber 5 is evacuated by means of a vacuum pump 50 to a pressure of 300mbar or less. In a further development of the method, the pressure is set in the range of 1 to 300mbar, in particular in the range of 5 to 100mbar, particularly preferably in the range of 5 to 50mbar, without being limited to this example. The silane is evaporated in vacuo such that the silane molecules 7 are distributed in the vacuum chamber 5 and deposited on the surface and thereby also on the surface 2 of the glass article 1 arranged in the vacuum chamber 5. According to this embodiment, the water in the vacuum chamber 5 in the form of air humidity is removed as much as possible by means of the vacuum pump 50. The deposition is thus carried out in an anhydrous atmosphere. By anhydrous atmosphere is meant in the present invention a partial pressure of water of less than 10mbar, preferably less than 3mbar, particularly preferably less than 1mbar. In particular no water or water vapor is added during the coating process. The chlorosilanes will not hydrolyze prior to deposition on the glass surface, which would result in the formation of, for example, oligomers.

Due to the low pressure in the chamber, the silane evaporates even if the vapor pressure of the silane is low enough at room temperature. The silane molecules, although having a certain volatility in vacuum, adhere very firmly to the surface 2 of the glass article 1. In a particularly preferred embodiment, the silane molecules 7 are covalently bonded to the surface 2 of the glass article 1. Covalent bonding can be carried out in particular by means of one or more chlorine atoms bonded to the silicon atom at the end of the chain.

In order to fix and homogenize the coating of silane molecules 7 on the surface 2 of the glass article 1, in particular in order to support the formation of covalent bonds of silane molecules 7 on the surface 2, in a preferred development of the method, the glass article 1 is subjected to a temperature treatment after deposition at a temperature between 80 ℃ and 200 ℃, wherein the coating is formed into a monolayer, in particular by the temperature treatment. Tempering of the glass article 1 can be performed in the vacuum chamber 5. For this purpose, in the exemplary embodiment shown, a heating element 51 is provided which is arranged in the vacuum chamber 5. The glass article 1 can be heated under vacuum or after venting the vacuum chamber 5. It is also possible to remove the glass article 1 after coating and then temper it in a separate oven.

Fig. 2 schematically shows a glass article 1, which can be obtained by the aforementioned method. The glass article 1 comprises a glass substrate 3 having a surface 2 on which a coating 9 is deposited. The coating 9 comprises linear silane molecules 7. As schematically shown, the silane molecules have at one end at least a dichlorinated silicon atom, wherein the end of the silane molecule is bonded to the surface 2 of the glass article 1. Without being limited to the specifically illustrated examples, it is generally preferred that the silane atom at that end be fully chlorinated or trichlorinated. The other end of the silane molecule 7 is formed by a chain 70 having at least four perfluorocarbon atoms as in the example shown. The fluorinated chains of the silane molecules 7 are directed outwards or away from the surface 2 due to the end bonds located opposite. In fig. 2, the silane molecules 7 are shown entirely in the form in which they are evaporated in the vacuum chamber. But can form bonds other than those shown when bonded to a surface. Thus, covalent bonding can occur, for example, by cleavage or substitution due to the formation of Si-O bonds.

Fig. 3 shows another possible connection of silane molecules 7 to the glass surface 2. It is conceivable that the silicon atoms of the silane molecules 7 are connected to the glass surface 2 via a plurality of bonds 72, preferably via 3 bonds 72. In this case it is conceivable that these bonds 72 are covalent si—o bonds. Since a minute water layer is absorbed on the glass surface 2, the chlorine atom is replaced with an OH group. The bond 72 may be a non-covalent bond. In the example shown in fig. 3, the silane molecules 7 can also be attached to the glass surface via a plurality of, preferably three, chlorine atoms.

As shown, the silane molecules 7 are preferably formed as a monolayer. Thus, the coating 9 is very thin and not visually apparent.

According to one embodiment, the silane molecules 7 are self-organized in a monolayer. The perfluorinated alkyl chains are directed away from the glass surface 2 by a mutual repulsive interaction between the polar glass surface 2 and the perfluorinated alkyl chains 70. By this self-organization, the coating 9 having a perfluorinated surface can be obtained even in the case of a single layer by using perfluorinated silane 7. Thus, the coating 9, although formed as a single layer and thus having a low layer thickness, has a completely or at least substantially fluorinated surface which has a mutual repulsive effect.

The TOF-SIMS spectra of two examples and two comparative examples are shown in FIGS. 4-8. Fig. 4 shows here the relationship between the detected fluorine ions and silicon ions and the sputtering time. The sputtering time is a measure of the layer thickness stripped by sputtering. Thus, a signal of high sputtering time represents a large layer thickness. Curves 20 and 21 here show the intensity curves of the fluoride ions (curve 20) and the silicon ions (curve 21) of the first embodiment. In this example, a coating was deposited from the vapor phase using the method according to the invention, and then heat treated at 115 ℃ for 30 minutes. Curve 30 shows the intensity curve of the fluoride ions of the second embodiment. The manufacturing method of the second embodiment differs from the manufacturing method of the first embodiment in that the coating layer 9 is dried in air after the deposition thereof, so that the second embodiment is not subjected to a heat treatment after the coating process. Curves 40 and 41 show the intensity curves of the fluoride ion 40 or the silicon ion 41 of the first comparative example. In the first comparative example, the glass surface was coated with the same silane as in the two examples, but not in vacuum. Thus deposition is performed by wet chemical methods in the presence of water. Thus, the deposition is performed using an aqueous solution of silane or at least an aqueous solution. The deposited coating was then heat treated at 115 ℃ for 30 minutes.

In a second comparative example, in which the fluoride ion intensity profile is shown by curve 50 and the silicon ion intensity profile is shown by curve 51, the coating is also wet-chemically deposited. The second comparative example differs from the first comparative example in this case in that the air drying is carried out here only at room temperature. According to fig. 4, it is shown that the intensities of fluoride ions and silicon ions can be detected only in a relatively short sputtering time in both embodiments, and that both embodiments have a relatively thin layer thickness. Furthermore, in both embodiments the maximum intensity of the fluoride ions 20, 30 can be detected in a very short sputtering time, which decreases drastically with increasing sputtering time. Only the region of the surface of the coating 9, i.e. the region furthest from the glass surface 2, is stripped off in a short sputtering time and its ionic strength is detected.

In fig. 5, curves 20, 30, 40, 50 of fluoride ions are shown for a short sputtering time. As can be seen from fig. 5, the curves 20, 30 have their maximum values and decrease rapidly in a very short sputtering time. However, the strength of the curves 40 and 50 of the comparative example was less significantly reduced with the increase in sputtering time.

Thus, the curves 20, 30 for fluoride ions can be concluded as follows: fluorine is only present in the area near the surface of the coating 9. This shows that the coating 9 of the example is constructed as a monolayer and that the coating 9 has a self-organizing structure in which the silane molecules on the glass surface are oriented such that all perfluorinated alkyl groups are oriented in the direction of the coating surface. It can be assumed that due to the orientation of the fluorinated portion 70 of the coating and its hydrophobic nature, the silicon atoms are shielded by the fluorinated portion after the monolayer is deposited, making the already deposited silane non-polymerizable or difficult to polymerize with other silanes. Furthermore, other silanes are prevented from accumulating on the surface of the coating due to the mutual repulsive interaction of the fluorine-containing surface of the coating 9. It can also be demonstrated that the coating is formed as a single layer according to the silicon ion concentration profile 21 of the first embodiment.

The mutual repulsive interaction of the fluorine-containing coating surfaces also explains the surprisingly good properties of the coating with respect to its cleaning properties and its anti-adhesion properties in the case of very thin layer thicknesses.

In contrast, the two comparative examples show concentration curves 40, 50 of fluoride ions, which can be detected even if the sputtering time is long. In this case, the strength of the fluoride ion is only slowly decreased. This shows, on the one hand, that the layer thickness is much greater than in the example coating, and on the other hand that the fluorinated alkyl groups are distributed in the coating over a relatively large layer width. Unlike the examples, enrichment of fluorine concentration in the area of the coating near the surface appears less pronounced.

It can also be seen from the difference in the curves 40 and 50 of the two comparative examples that the concentration profile of perfluorinated alkyl groups and silicon within the coating can be affected by the heat treatment when the coating is applied by wet chemical methods. Thus, the coating of the first comparative example, which was subjected to a temperature of 115 ℃ for 30 minutes, exhibited an increase in fluorine concentration 40 in the region close to the surface, whereas silicon concentration 41 increased only when the sputtering time was long. In this case, the two concentration curves 40, 41 have approximately S-shaped curves.

In contrast, the concentration curves 20, 30 of the two embodiments do not differ, or at least do not differ significantly. This shows that the treatment at this temperature has a significantly lower effect on the orientation of the silane bonded to the glass surface.

In the second comparative example, silicon ions were detected even when the sputtering time was very low (curve 51). The concentration profile 51 is substantially constant over the measured sputtering time. Because the deposition is carried out in the presence of water, it can be assumed that at least some of the chlorosilane groups of the silane molecules 7 hydrolyze in the regions close to the surface or in regions not in contact with the glass surface, and thus the silane polymerizes within the coating.

Fig. 6 shows ion concentration curves of carbon ions of two examples (curves 23 and 33) and two comparative examples. The curve 43 corresponds here to the concentration curve of the first comparative example, in which the coating is subjected to a temperature treatment. Fig. 7 also illustrates the formation of a single layer in both embodiments.

The same applies to fig. 7 and 8. Fig. 7 shows the corresponding ion concentration curves for the chloride ions of the second example (curve 34) and the first and second comparative examples (curves 44 and 45). Fig. 8 shows a portion of the ion concentration curve shown in fig. 7 in the case of a short sputtering time. The curves 24, 34 of the two embodiments show here the maximum of the sputtering time between 10 and 20 s. This can indicate that no chlorine is contained in the outer region of the coating near the surface and that the chlorine concentration increases in the inner region of the coating.

Generally, shorter silane molecules 7 are preferred for the coating 9. In a preferred embodiment, a total of up to twelve, preferably up to nine, linearly bonded atoms in chain length and silane molecules 7 comprising terminal silicon atoms are deposited. Particularly preferred are silane molecules 7 having a total of nine atoms, i.e. terminal silicon atoms and chain lengths of eight carbon atoms attached thereto.

According to another particularly preferred embodiment, the perfluorinated chain 70 is not directly attached to the silicon chloride atom. Instead, one or more CH ₂ groups 71 may be attached to at least the terminal bischlorinated silicon atom. In the example shown, a chain of two CH ₂ groups is attached to the terminal silicon chloride atom. The chain 70 with fluorinated atoms is then linked to a chain of two CH ₂ groups. One or more CH ₂ groups 71 are advantageous to promote covalent bonding of silicon atoms or bonding of silane chloride groups on the surface 2 of the glass article 1.

In a particularly preferred embodiment, the silane comprises trichloro (1 h,2 h-perfluorooctyl) silane molecules, which are evaporated in vacuo and deposited on the surface 2 of the glass article 1 to produce the coating 9. The example shown in fig. 2 likewise shows a coating 9 consisting of trichloro (1 h,2 h-perfluorooctyl) silane molecules. The silanes preferably used have the formula C ₈H₄Cl₃F₁₃ Si.

These molecules proved to be optimal for producing a strong temperature-resistant coating 9 on glass, in particular glass containing silicate. If the chain length is too long, the bonds on the substrate may break at high temperatures. On the other hand, a shorter chain length reduces the hydrophilic character of the coating 9.

Ellipsometry of the layer thickness indicated that the coating 9 with the above-mentioned trichloro (1 h,2 h-perfluorooctyl) silane molecules had a layer thickness of 2.4 nm. This value indicates that the silane molecules actually form a monolayer. Not limited to this example, according to one embodiment, the coating 9 has a layer thickness of less than 3 nanometers.

Fig. 9 shows an ellipsometric measurement of the layer thickness of the coating 9 on the glass article 1. The measurements were recorded at 7 day intervals. Silylation is carried out between measurement points 3 and 4 according to the method described herein. The layer thickness was measured at measurement points 4 and 5, respectively, to be 2.4 nm, corresponding to a monolayer of silane molecules. UV combustion is then performed. Where the hydrocarbon portion including perfluorinated chains 70 is removed. Finally, the rest is the silicon atoms, possibly SiOx, bonded to the glass surface 2, which appears to increase slightly in layer thickness by about 0.75 nm.

In a further preferred embodiment, the glass product 1 is formed from soda lime glass or borosilicate glass. Both glasses contain SiO ₂ or silicate-containing glasses. The SiO ₂ content enables good bonding of the silane molecules 7 to the surface of the glass. Soda lime glass is particularly preferred in terms of adhesion to silane molecules. Regardless of the type of glass, it is particularly preferred that the surface 2 to which the silane molecules 7 are bonded is formed of glass of the glass substrate 3 such that the surface 2 is not formed of an interlayer composed of a material other than glass.

Other components of the glass used can influence the bonding of the silane molecules 7 on the surface 2. It has been found here that high levels of Na ₂ O in the glass composition impair the bonding, but this effect can also be brought about by co-action with other glass components if desired. In any event, in another preferred embodiment, it is generally provided that the glass article 1 is formed from a glass having a composition with a Na ₂ O content of less than 10 weight percent. Alternatively, na ₂ O may also be depleted on the surface of the glass. This is achieved, for example, by plasma treatment of the glass. Another solution is the surface substitution of sodium by potassium, which is achieved for example by chemical tempering. According to another embodiment, the glass article is chemically tempered prior to coating with silane molecules 7, wherein sodium atoms are at least partially replaced by potassium atoms on the surface 2 of the glass.

In one embodiment, the glass is a soda lime glass having the following composition expressed in weight percent:

Component (A)	(Wt.%)
		SiO₂	40-81
Al₂O₃	0-6
		B₂O₃	0-5
Li₂O+Na₂O+K₂O	5-30
		MgO+CaO+SrO+BaO+ZnO	5-30
TiO₂+ZrO₂	0-7
		P₂O₅	0-2

		CTE	5.53-9.77

As ₂O₃、Sb₂O₃、SnO₂、SO₃, cl, F and/or CeO ₂ may be added As refining agents, preferably in total amounts of 0 to 2% by weight.

In another embodiment, the glass of the glass article is borosilicate glass having the following composition in weight percent:

Component (A)	(Wt.%)
		SiO₂	60-85
Al₂O₃	0-10
		B₂O₃	5-20
Li₂O+Na₂O+K₂O	2-16
		MgO+CaO+SrO+BaO+ZnO	0-15
TiO₂+ZrO₂	0-5
		P₂O₅	0-2

		CTE	3.0-9.01

As ₂O₃、Sb₂O₃、SnO₂、SO₃, cl, F and/or CeO ₂ may also be added As refining agents, preferably in total amounts of 0 to 2% by weight.

According to another embodiment, the glass of the glass article is a glass-ceramic. Preferably, lithium aluminosilicate glass ceramics are used here, in particular for thermal applications, for example for kitchen ranges.

The coated glass articles described herein below are compared to like coated glass articles currently available on the market to investigate their properties. Generally, not limited to the example shown in fig. 4, according to one embodiment, a glass article surface 2 provided with a monolayer of silane molecules (7) in a glass article 1 according to the present disclosure has a contact angle of at least 100 ° with respect to water. In this regard, fig. 10 shows a bar graph of contact angles of different coatings that can be cleaned simply before and after temperature treatment. In particular, fig. 10 shows a bar graph of three groups (a), (b) and (c), wherein groups (a) and (b) show measurements of glass articles currently available on the market with a surface that can be cleaned easily. Group (c) characterizes the measurements obtained on the glass article 1 described herein. All glass articles herein have a surface comprising hydrophobic properties. The leftmost columns in groups (a), (b), (c), respectively, show contact angle measurements prior to any temperature treatment. The remaining columns are indicated by the corresponding temperatures and treatment durations. The upper part of the outer column is marked with a corresponding measurement of the contact angle. As can be seen from the bar graph, the contact angle decreases with the duration of the temperature and the level of the temperature. The coating 9, as described herein, always exhibits a larger contact angle than two glass articles available on the market. The contact angle in said glass article 1 after a treatment duration of 24 hours at a temperature of 250 c is thus still 10 ° greater than that of the glass article from which the measurements of group (b) were made. As can be seen from fig. 10, the characteristic of a contact angle of at least 100 ° is fulfilled in this particular example even at a temperature load of 250 ℃ for 24 hours. While the comparative examples always show a contact angle of less than 100 ° after each temperature load used.

Fig. 11 shows the results of a baking test for a coating that can be cleaned simply, which was also used for the test according to fig. 8. For this test the same amount of curd was applied on coatings (a) and (b) and coating (c) according to the present disclosure, respectively. The glass article with the curd is then heated such that the curd burns. The glass article is heated for 20 minutes to 300 ℃.

The glass article is then cleaned. This process was performed three times for each product, with the curd being applied to the same respective sites during all of the executions. Cleaning is performed by simple wiping. The numbers 1,2 and 3 above the column in fig. 11 identify this implementation. The surface where the char curd residue was also present was measured after cleaning. The columns give the area ratio of the reference relative to 100% of the occupied portion left on the uncoated glass article after cleaning, respectively. 100% thus represents the number of pixels in the camera image that represent the area that remains contaminated after baking and wiping the uncoated reference sample, rather than the area occupied before baking and wiping. The reference for 100% area occupation is shown on the left side of the graph. As can be seen from fig. 11, all articles exhibited very good cleanability after the first bake. The area ratio was zero percent in all samples, which corresponds to the baked curd being completely removed. But both comparative samples (a) and (b) showed significantly increased area ratios for the next runs 2 and 3. The area ratio of sample (a) after the third pass was 70% and the area ratio of sample (b) was about 75%. In contrast, the area ratio of sample (c) in glass article 1 manufactured according to the method disclosed herein remains correspondingly zero after all processes. This percentage relates to a reference value of 100% as determined above, which represents the area of the uncoated reference sample that was also contaminated after baking and wiping.

The cleanability of the glass article 1 disclosed herein is maintained even after multiple toasts of food, whereas the cleanability of glass articles currently available on the market is degraded very rapidly. Thus, without being limited to the example shown, in a modification the glass product 1 has a surface 2 through which the baked curd can be completely removed from the same location on the surface by wiping at least twice, preferably at least three times in sequence. Other baked goods can also be cleaned very well by simple wiping with the coating described herein. After baking the cottage cheese at 300 ℃ for 20 minutes the cottage cheese can be removed by wiping leaving only 0.32% of the occupancy. In the case of tomato paste baked under the same conditions, the remaining occupancy was 0.27%. The occupancy left in the case of curd corresponds to 0.00% of the result already discussed with reference to fig. 11. This percentage does not refer to the area previously occupied by the corresponding food, but to the area at 100% that remains contaminated after baking and wiping of the uncoated reference sample.

A photographic image of the surface of the glass article after baking the food and cleaning is shown in fig. 12. Photographing was performed on an uncoated reference and a coated glass article 1 according to the present disclosure. The photographs on the coated glass article 1 form the basis for the above-described evaluation of the occupancy cottage cheese (0.32%), tomato paste (0.27%) and curd (0.00%) remaining after baking and wiping. The photograph of fig. 12 is divided into two columns (a) and (b). Column (a) shows photographs on uncoated glass articles. Column (b) contains photographs of glass article 1 coated with a silane monolayer according to the present disclosure. The photograph represented by (i) shows the surface of the corresponding glass article after baking the cottage cheese. The photograph represented by (ii) shows the glass product after baking the tomato paste and subsequent cleaning. The photograph represented by (iii) shows the result after baking the curd and cleaning. Cleaning is performed by wiping the surface as described above. As can be seen by comparing the two series of pictures, the glass article 1 with the coating as described in the present disclosure has a very simple cleanability, since even burnt food can be almost completely removed by simple wiping.

The coating 9 according to the present disclosure has proved to be very uniform in terms of hydrophobicity. Thus, without being limited to a particular example, in one embodiment, the coating 9 has a contact angle with respect to water, which varies only by up to 3 ° with at least 10, preferably at least 20, measurement points evenly distributed on the surface. In one example, uniformity is determined by measuring contact angles at different locations of the surface 2. The contact angle was determined at 12 locations within the 150x 300mm ² area. The measurement is performed before the temperature load or after 30 minutes at a temperature load of 250 ℃. The temperature cycle was repeated five times. The average deviation of the average value of the contact angles before and after the temperature cycle is only ±2°.

A preferred application of the glass articles described herein is a cooktop. The invention is particularly suitable for a stove top or induction stove top. Fig. 13 shows a stove top 12 with a glass product 1. The glass product 1 is constructed in the form of a disk and forms a base plate which also serves as a cover for the internal components of the cooking hob (such as supply lines and control electronics). The stove top surface 12 is in particular gas-driven. For this purpose, one or more gas burners 14 are provided, which pass through openings in the glass product 1. The bracket 18 is used to place the cookware over the burner 14. In the example shown, the support 18 is fastened to this with a support leg 19 at a distance from the base plate or from the glazing 1. The stent can be variously designed. Each gas burner 14 can be ignited and regulated with an operating element 16, for example in the form of a rotary switch. At least the user-visible surface 2 of the glass article 1 is coated with a coating 9 in the form of a monolayer of silane molecules 7, enabling a simple cleaning of the burnt foodstuff from the hob surface 12.

Another preferred application of the glazing 1 is as a control panel, in particular in large household appliances. According to one embodiment, the glazing 1 is used as a control panel in a dishwasher or steamer.

The embodiments and examples described herein may naturally be combined with each other within the scope of the claims.

List of reference numerals

Claims

1. A method for manufacturing a glass article having a surface that can be cleaned easily, wherein,

-Providing a glass article (1) and transferring it into a vacuum chamber (5), and

-Generating a vacuum with a maximum pressure of 300mbar in said vacuum chamber (5), and

-Evaporating silane in said vacuum, depositing silane on the surface (2) of said glass article (1), wherein

-The silane comprises linear silane molecules (7) having at one end at least a bischlorinated silicon atom, and wherein

-After deposition, the silane molecules are bonded to the surface (2) of the glass article by means of silane functional groups, and wherein

-The other end of the silane molecule is formed by a chain with at least four perfluorinated atoms such that the chain points outwards after bonding to the surface (2) of the glass article (1), and wherein the silane molecule (7) forms a coating (9) in the form of a monolayer after vapour deposition.

2. The method according to the preceding claim, characterized in that the silane molecules (7) are covalently bonded to the surface of the glass article (1).

3. A method according to any of the preceding claims, characterized in that the pressure is set in the vacuum chamber in the range of 5 to 100mbar, preferably in the range of 5 to 50 mbar.

4. A method according to any one of claims 1 to 3, characterized in that the silane molecules (7) are covalently bonded to the surface (2) of the glass article (1) via a plurality, preferably via 2 bonds.

5. The method according to any one of the preceding claims, characterized in that after deposition the glass article (1) is subjected to a temperature treatment at a temperature between 80 ℃ and 200 ℃, wherein the coating (9) is formed as a single layer by the temperature treatment.

6. A method according to any of the preceding claims, characterized in that there are deposited atoms having a total chain length of at most twelve, preferably at most nine, linear bonds and silane molecules comprising terminal silicon atoms.

7. The method of any of the preceding claims, wherein a silane molecule is deposited wherein one or more CH ₂ groups are attached to the silane functionality.

8. The method according to any of the preceding claims, characterized in that the silane has trichloro (1 h,2 h-perfluorooctyl) silane molecules, which are evaporated in vacuo and deposited on the surface (2) of the glass article (1) to produce a coating (9).

9. Glass article (1), in particular a glass article (1) producible by a method according to any one of the preceding claims, wherein the glass article (1) has a surface (2) on which linear silane molecules (7) are attached via silane functional groups, wherein the silane molecules (7) form a coating (9) on the surface (2) in the form of a monolayer, and wherein the other end of the silane molecules is formed by chains with at least four perfluorinated atoms, such that the chains in the monolayer are directed outwards.

10. Glass article (1) according to the preceding claim, characterized in that it is formed from a soda lime glass or borosilicate glass or glass ceramic, preferably a lithium aluminosilicate glass ceramic.

11. Glass article (1) according to any one of the preceding claims, characterized in that it is formed from a glass having a composition with a Na ₂ O content of less than 10% by weight.

12. Glass article (1) according to any one of the preceding claims, characterized in that the surface (2) of the glass article provided with a monolayer of silane molecules (7) has a contact angle of at least 100 ° with respect to water.

13. A cooktop (12), in particular a cooktop or induction cooktop, comprising a glass article (1) according to any of claims 9 to 12 or a glass article (1) manufactured by a method according to any of claims 1 to 8.

14. Use of the glass article (1) according to any of claims 9 to 12 as a control panel in a household appliance, in particular as a control panel of a dishwasher or steamer.