METHOD FOR PRODUCTION OF A COATED, CHEMICALLY PRESTRESSED GLASS SUBSTRATE HAVING ANTI-FINGERPRINT PROPERTIES AND PRODUCED GLASS SUBSTRATE

Abstract

The invention relates to a method for producing a coated, chemically prestressed glass substrate having anti-fingerprint properties. The method includes: applying at least one functional layer to a glass substrate; chemically prestressing the coated glass substrate by an ion exchange, where existing smaller alkali metal ions are exchanged for larger alkali metal ions, and are enriched in the glass substrate and the at least one functional layer; activating the surface of the at least one functional layer, where if more than one functional layer is present the surface of the outermost or uppermost layer is activated, the activating including one of several alternatives; and applying an amphiphobic coating to the at least one functional layer of the glass substrate, where, as a result of the activation process, the functional layer interacts with the amphiphobic coating.

Claims

1. A method for producing a coated, chemically prestressed glass substrate having anti-fingerprint properties, comprising: applying at least one functional layer onto a glass substrate to form a coated glass substrate; chemically pre-stressing said coated glass substrate by an ion exchange, wherein existing smaller alkali metal ions are exchanged for larger alkali metal ions and are enriched in said glass substrate and said at least one functional layer; activating a surface of said at least one functional layer, wherein if said at least one functional layer comprises a plurality of functional layers a surface of an outermost or uppermost layer is activated, wherein said activating comprises one of the following alternatives: 1) treating said surface of said at least one functional layer with an alkaline aqueous solution and subsequent washing with water; 2) treating said surface of said at least one functional layer with an acidic aqueous solution and subsequent washing with water; 3) treating said surface of said at least one functional layer with an alkaline aqueous solution and subsequent washing with water, treating said surface of said at least one functional layer with an acidic aqueous solution following said treatment with said alkaline aqueous solution and subsequent washing with water; 4) washing said surface of said at least one functional layer with an aqueous washing solution containing at least one tenside and subsequent rinsing with water; 5) washing said surface of said at least one functional layer with water; 6) one of alternatives 1, 2, 3, and 4 combined with ultrasonic cleaning; 7) treating said surface of said at least one functional layer with oxygen-plasma; and 8) one of alternatives 1, 2, 3, 4, 5, and 6 combined with oxygen-plasma treatment; and applying an amphiphobic coating onto said at least one functional layer of said glass substrate, whereby said at least one functional layer interacts with said amphiphobic coating as a result of said activating.

2. The method according to claim 1, wherein said alkaline aqueous solution has a pH value above 9 and contains at least one of sodium and potassium ions.

3. The method according to claim 1, wherein at least one of said treating steps comprises at least one of spreading, infusion, spraying, and dipping said coated glass substrate in said respective solution for a defined time period at a temperature between 20 C. and a boiling point of said respective solution.

4. The method according to claim 1, wherein said acidic aqueous solutions includes at least one of an inorganic acid and an organic acid.

5. The method according to claim 1, wherein said at least one functional layer comprises an inorganic layer defining at least one of an optically effective layer, an antireflective layer, an antiglare layer, an antidazzle layer, an anti-scratch layer, a conductive layer, a cover layer, an adhesion promoting layer, a protective layer, an abrasion resistant layer, a photocatalytic layer, an antimicrobial layer, a decorate layer, a colored layer, and an electrochromic layer.

6. The method according to claim 1, wherein said chemical pre-stressing comprises one of: dipping said coated glass substrate in a substance containing at least one of potassium, rubidium, and cesium; vapor deposition; and temperature-activated diffusion.

7. The method according to claim 6, wherein said chemical pre-stressing comprises dipping said coated glass substrate into a solution containing antimicrobially effective ions and at least one of potassium, rubidium, and cesium.

8. The method according to claim 1, wherein said at least one functional layer one of comprises and consists of an Si-compound, wherein if said at least one functional layer comprises a plurality of functional layers then an outermost or uppermost layer one of comprises and consists of an Si-compound.

9. The method according to claim 8, wherein said Si-compound comprises at least one of: a silicon oxide; SiO.sub.x with x being less than or equal to 2; SiOC; SiON; SiOCN; Si.sub.3N.sub.4; SiO.sub.x combined with a volume of hydrogen, wherein x is less than or equal to 2; and a silicon mixed oxide including a mixture of one silicon oxide with one oxide of at least one of aluminum, tin, magnesium, phosphorus, cerium, zircon, titanium, cesium, barium, strontium, niobium, zinc, boron and magnesium fluoride.

10. The method according to claim 1, wherein said at least one functional layer is applied at a thickness of greater than 1 nm.

11. The method according to claim 1, wherein said at least one functional layer comprises an antireflective coating.

12. The method according to claim 11, wherein said antireflective coating consists of a single layer comprising at least one of a metal oxide, a fluorine doped metal oxide, a metal fluoride, a silicon-oxide, a fluorine doped SiO.sub.2, a fluorine doped quartz glass, a magnesium fluoride silicon oxide, and a silicon mixed oxide.

13. The method according to claim 11, wherein said antireflective coating comprises a plurality of layers, wherein said plurality of layers alternate one of: high refractive layers and low refractive layers; and medium refractive layers, high refractive layers, and low refractive layers.

14. The method according to claim 13, wherein each of said plurality of layers comprises or consists of at least one of titanium oxide, niobium oxide, tantalum oxide, cerium oxide, hafnium oxide, silicon oxide, magnesium fluoride, aluminum oxide, zircon oxide, yttrium oxide, gadolinium oxide, and silicon nitrate, said antireflective coating having a thickness of 50 nm to 100 m.

15. The method according to claim 1, further comprising drying said coated glass substrate after said activating.

16. The method according to claim 1, wherein said glass substrate is a lithium aluminum silicon glass comprising the following in weight-%: TABLE-US-00013 SiO.sub.2 55-69; Al.sub.2O.sub.3 19-25; Li.sub.2O 3-5; Sum Na.sub.2O + K.sub.2O 0-30; Sum MgO + CaO + SrO + BaO 0-5; ZnO 0-4; TiO.sub.2 0-5; ZrO.sub.2 0-3; Sum TiO.sub.2 + ZrO.sub.2 + SnO.sub.2 2-6; P.sub.2O.sub.5 0-8; F 0-1; and B.sub.2O.sub.3 0-2.

17. The method according to claim 1, wherein said glass substrate is a soda lime-silicon glass comprising the following in weight-%: TABLE-US-00014 SiO.sub.2 40-80; Al.sub.2O.sub.3 0-6; B.sub.2O.sub.3 0-5; Sum Li.sub.2O + Na.sub.2O + K.sub.2O 5-30; Sum MgO + CaO + SrO + BaO + ZnO 5-30; Sum TiO.sub.2 + ZrO.sub.2 0-7; and P.sub.2O.sub.5 0-2.

18. The method according to claim 1, wherein said glass substrate is a borosilicate glass comprising the following in weight-%: TABLE-US-00015 SiO.sub.2 60-85; Al.sub.2O.sub.3 1-10; B.sub.2O.sub.3 5-20; Sum Li.sub.2O + Na.sub.2O + K.sub.2O 2-16; Sum MgO + CaO + SrO + BaO + ZnO 0-15; Sum TiO.sub.2 + ZrO.sub.2 0-5; and P.sub.2O.sub.5 0-2.

19. The method according to claim 1, wherein said glass substrate is an alkali-aluminosilicate glass comprising the following in weight-%: TABLE-US-00016 SiO.sub.2 40-75; Al.sub.2O.sub.3 10-30; B.sub.2O.sub.3 0-20; Sum Li.sub.2O + Na.sub.2O + K.sub.2O 4-30; Sum MgO + CaO + SrO + BaO + ZnO 0-15; Sum TiO.sub.2 + ZrO.sub.2 0-15; and P.sub.2O.sub.5 0-10.

20. The method according to claim 1, wherein said glass substrate is a low alkali-aluminosilicate glass comprising the following in weight-%: TABLE-US-00017 SiO.sub.2 50-75; Al.sub.2O.sub.3 7-25; B.sub.2O.sub.3 0-20; Sum Li.sub.2O + Na.sub.2O + K.sub.2O 1-4; Sum MgO + CaO + SrO + BaO + ZnO 5-25; Sum TiO.sub.2 + ZrO.sub.2 0-10; and P.sub.2O.sub.5 0-5.

21. The method according to claim 1, wherein said glass substrate is a siliceous glass comprising the following in weight-%: TABLE-US-00018 SiO.sub.2 10-90; Al.sub.2O.sub.3 0-40; B.sub.2O.sub.3 0-80; Na.sub.2O 1-30; K.sub.2O 0-30; CoO 0-20; NiO 0-20; Ni.sub.2O.sub.3 0-20; MnO 0-20; CaO 0-40; BaO 0-60; ZnO 0-40; ZrO.sub.2 0-10; MnO.sub.2 0-10; CeO 0-3; SnO.sub.2 0-2; Sb.sub.2O.sub.3 0-2; TiO.sub.2 0-40; P.sub.2O.sub.5 0-70; MgO 0-40; SrO 0-60; Li.sub.2O 0-30; Li.sub.2O + Na.sub.2O + K.sub.2O 1-30; SiO.sub.2 + B.sub.2O.sub.3 + P.sub.2O.sub.5 10-90; Nd.sub.2O.sub.5 0-20; V.sub.2O.sub.5 0-50; Bi.sub.2O.sub.3 0-50; SO.sub.3 0-50; and SnO 0-70, wherein the content of SiO.sub.2+P.sub.2O.sub.5+B.sub.2O.sub.3 is 10-90 weight-%.

22. The method according to claim 1, wherein said glass substrate is a lead glass comprising the following in weight-%: TABLE-US-00019 PbO 20-80; SiO.sub.2 20-60; K.sub.2O 0-10; Na.sub.2O 1-10; BaO 0-20; SrO 0-20; Al.sub.2O.sub.3 0-10; CaO 0-10; F.sub.2O.sub.3 0-1; Sb.sub.2O.sub.3 0-1; ZnO 0-20; B.sub.2O.sub.3 0-20; and ZrO.sub.2 0-10.

23. The method according to claim 1, wherein said glass substrate comprises at least one of a colored oxide, a rare earth oxide, and a refining agent.

24. The method according to claim 1, wherein said glass substrate is one of a glass ceramic and a ceramized glass of a starting glass comprising the following in weight-%: TABLE-US-00020 Li.sub.2O 3.2-5.0; Na.sub.2O 0-1.5; K.sub.2O 0-1.5; Sum Na.sub.2O + K.sub.2O 0.2-2.0; MgO 0.1-2.2; CaO 0-1.5; SrO 0-1.5; BaO 0-2.5; ZnO 0-1.5; Al.sub.2O.sub.3 19-25; SiO.sub.2 55-69; TiO.sub.2 1.0-5.0; ZrO.sub.2 1.0-2.5; SnO.sub.2 0-1.0; Sum TiO.sub.2 + ZrO.sub.2 + SnO.sub.2 2.5-5.0; and P.sub.2O.sub.5 0-3.0

25. The method according to claim 1, wherein said glass substrate is one of a glass ceramic and a ceramizable glass of a starting glass comprising the following in weight-%: TABLE-US-00021 Li.sub.2O 3-5; Na.sub.2O 0-1.5; K.sub.2O 0-1.5; Sum Na.sub.2O + K.sub.2O 0.2-2; MgO 0.1-2.5; CaO 0-2; SrO 0-2; BaO 0-3; ZnO 0-1.5; Al.sub.2O.sub.3 15-25; SiO.sub.2 50-75; TiO.sub.2 1-5; ZrO.sub.2 1-2.5; SnO.sub.2 0-1.0; Sum TiO.sub.2 + ZrO.sub.2 + SnO.sub.2 2.5-5; and P.sub.2O.sub.5 0-3.0.

26. The method according to claim 1, wherein said glass substrate is one of a glass ceramic and a ceramizable glass of a starting glass comprising the following in weight-%: TABLE-US-00022 Li.sub.2O 3-4.5; Na.sub.2O 0-1.5; K.sub.2O 0-1.5; Sum Na.sub.2O + K.sub.2O 02.-2; MgO 0-2; CaO 0-1.5; SrO 0-1.5; BaO 0-2.5; ZnO 0-2.5; B.sub.2O.sub.3 0-1; Al.sub.2O.sub.3 19-25; SiO.sub.2 55-69; TiO.sub.2 1.4-2.7; ZrO.sub.2 1.3-2.5; SnO.sub.2 0-0.4; Sum TiO.sub.2 + SnO.sub.2 less than 2.7; P.sub.2O.sub.5 0-3; and Sum ZrO.sub.2 + 0.87 (TiO.sub.2 + SnO.sub.2) 3.6-4.3.

27. The method according to claim 1, wherein said glass substrate is a glass ceramic containing one of high quartz mixed crystals and keatite mixed crystals as the predominant crystals phase, wherein a crystal size of said crystals is less than 70 nm.

28. The method according to claim 1, wherein said amphiphobic coating includes at least one layer comprising at least one of a layer on a fluorine basis, a fluororganic compound, a perfluorohydrocarbon, a perfluoropolyether, at least one silane, an alkyl-containing silane, and a fluoroalkyl-containing silane.

29. The method according to claim 1, wherein one of a textured layer and a patterned layer is located between said at least one functional layer and said glass substrate, wherein said one of a textured layer and a patterned layer has a roughness in the range of 5 nm to 5 m.

30. A coated, chemically prestressed glass substrate, produced according to the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0194] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0195] FIG. 1 is a schematic illustration of a coated glass substrate formed according to an exemplary embodiment of the present invention;

[0196] FIG. 2 is a diagram illustrating the breaking strength by a double ring test according to DIN EN 1288-5 (by excluding marginal influences) for a soda lime silicate glass K1 that is not chemically prestressed, a chemically prestressed soda lime silicate glass K2 with an antireflective coating, have a chemically prestressed soda lime silicate glass K3 with an antireflective coating, and an amphiphobic coating formed according to an exemplary embodiment of the present invention; and

[0197] FIG. 3 is a diagram wherein a reflection of a soda lime silicate glass that was not produced according to the invention is compared with an embodiment of a soda lime silicate glass produced according to the present invention.

[0198] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0199] FIG. 1 is a schematic illustration of a coated glass substrate formed according to an exemplary embodiment of the present invention.

[0200] A glass substrate 10, which can also be textured, is coated according to an exemplary method in a first step with at least one functional layer 20. Within the scope of the invention, this can be any desired functional coating, representing one layer or several layers. In the illustrated example, this is an antireflective coating comprising three layers with a medium refractive, high refractive and low refractive layer-system. A different functional coating can be present in one or more layers.

[0201] Glass substrate 10 can also be coated on both sides (not illustrated).

[0202] In a second step, glass substrate 10, together with functional coating 20, is chemically prestressed. This can occur in a conventional manner. For example, glass substrate 10 that is coated with the antireflective layer system 20 and that has a thickness, for example, of 1.1 mm is subjected to an ion exchange through dipping into an ion exchange bath, using potassium ions as the replacement ions for Na- and/or Li-ions, whereby immersion occurs for a sufficient duration at an appropriate temperature such that the potassium ions replace the existing Na- and/or Li-ions. Depending on the glass composition and the type of coating, the relevant parameters are established. For aluminosilicate and boroaluminosilicate glasses a penetration depth of, for example, DoL20 m can be obtained and for soda-lime silicate glasses a penetration depth of DoL5 m can be obtained. The ion exchange occurs on the coated side of glass substrate 10 through the antireflective layer system 20.

[0203] Subsequently, the activation process, with which the uppermost layer or outermost surface of functional coating 20 is treated, is performed. For this purpose, an NaOH-containing aqueous solution is sprayed onto the uppermost or outermost layer of the illustrated exemplary antireflective coating 20 and is subsequently washed with deionized water. The treatment duration and temperature are not particularly limited if the treated layer is not touched. Exemplary treatment times range from a few minutes, for example 0.1 minutes to 30 minutes. Exemplary treatment temperatures range from ambient temperature to boiling temperature of water, for example 20 C. to 95 C. The treatment temperature is selected from the stated range and is then maintained for the duration of the treatment. Other activation alternatives, as previously described, are also possible.

[0204] An amphiphobic coating 30 is subsequently applied onto antireflective coating 20 in a fourth step. This can, for example, be one or several layers on fluorine basis, or one or more silane-containing layers. Other known amphiphobic layers are also possible. The amphiphobic layer typically has a thickness in the range of 1 to 10 nm, such as 1 to 4 nm or 1 to 2 nm. As a result of amphiphobic coating 30, the glass article displays reduced adhesion of fingerprints and effortless removability of same. The amphiphobic surface is covalent and contributes to the fact that fingerprints and contaminations or dirt cannot easily adhere, so that a transfer of oils and contaminants from fingers onto the glass surface is minimized. The amphiphobic surface of the product further improves the removability of fingerprints while contaminations are minimized and the number of cleaning procedures are reduced. A reduction in the number and frequency of the cleaning procedures also reduces the possibility of damage to the glass surface caused by cleaning.

[0205] Due to activation, the surface of antireflective coating 20 interacts with amphiphobic coating 30, so that the amphiphobic coating possesses greater long-term stability and so that the beneficial properties of the amphiphobic coatingsuch as the anti-fingerprint characteristicare maintained over a considerably longer tie than without the activation process.

[0206] Due to the combination of chemical prestressing and subsequent activation of the coated glass substrate, the amphiphobic coating applied onto the coated glass substrate herewith displays a considerably greater long-term stability than would be achieved without activation of glass substrate and coating. As previously described, the properties of the amphiphobic coating are also positively influenced.

[0207] It was noted that, even if the content of alkali ions in the glass substrate and the uppermost layer is high, the amphiphobic coating is nevertheless long-term stable. The number of active bonding sites, for example of active SiOH-groups, is probably high enough due to one of the described activation variations in order to interact with the amphiphobic coating. Therefore, when activating the surface of the uppermost or outermost functional layer, already a very limited removal of alkali ions is sufficient to activate the surface of the functional layer in a sufficient manner.

[0208] FIG. 2 is a diagram wherein the breaking strength values are expressed in MPa for a soda lime silicate glass K1 that is not chemically prestressed; a chemically prestressed soda lime silicate glass K2 with an antireflective coating; and a chemically prestressed soda lime silicate glass K3 with an antireflective coating; and an amphiphobic coating formed according to an exemplary embodiment of the present invention. The stated breaking strength values were determined through a double ring test according to DIN EN 1288-5 (by excluding marginal influences) and through calculation according to DIN EN 12337-2. The calculation is based on a Weibull distribution. The test sizes were 1001004 mm.sup.2. Glasses K1, K2 and K3 have the same composition.

[0209] The prestressed, coated glasses formed according to the present invention have an increase in strength compared to glasses having the same composition but that were not prestressed; an increase in strength by a factor of at least 2 was achieved. The beneficial properties of the exemplary glass substrate K3 that are achieved with chemical prestressing are therefore not negatively impacted by the forming method.

[0210] FIG. 3 is a diagram wherein the reflective behavior of a soda lime silicate glass that was not produced according to the present invention is compared with a soda lime silicate glass produced according to the present invention. The reflection is protracted in % against the wavelength in nm.

[0211] Two soda lime silicate glasses with the same composition were usedone was produced with a method according to the present invention while the other one was not. The broken line shows the reflection of a chemically prestressed soda lime silicate glass with an antireflective (AR) coating, which is not according to the reflection. The solid line shows the reflection of a chemically prestressed soda lime silicate glass that, after chemical prestressing underwent a surface activation and was subsequently provided with an amphiphobic coating (according to the present invention).

[0212] FIG. 3 therefore shows, that the optical properties of the glass substrate that is produced according to the present invention are changed only very slightly.

[0213] Neutral Salt Spray Test (NSS-Test) for Evaluation of the Properties of the Amphiphobic Coating

[0214] In order to substantiate that the substrates produced according to the present invention have better properties, especially long-term properties, if the surface is activated prior to coating with the amphiphobic coating, the substrates underwent testing. To obtain a measure for the long-term durability, a contact angle measurement was performed after a long-lasting NSS-test (neutral salt spray test according to DIN EN 1096-2:2001-05).

[0215] For the herein illustrated test results, deionized water was used as the measuring fluid. The error tolerance of the measurement results is 3.

[0216] The neutral salt spray test in which the coated glass samples were exposed to a neutral salt water atmosphere for 21 days at constant temperature proved to be an especially challenging test. The saltwater spray mist causes stress in the coating. The glass samples are placed in a specimen holder, so that the samples form an angle with the vertical of 155. The neutral salt solution was produced by dissolving pure NaCl in deionized water, so that a concentration of 505 g/l at 252 C. was achieved. The salt solution was atomized via an appropriate nozzle in order to produce the salt spray mist. The operating temperature of the test chamber was 352 C.

[0217] Before the test and after 504 hours of test time, the contact angle to water was measured to characterize the stability of the hydrophobic property.

[0218] The amphiphobic coating used in the current example was Optool AES4-E by Daikin Industries Ltd., a perfluoroether with terminal silane residue.

[0219] An AR-coating produced in a Sol-Gel process was used as the functional layer. The glasses were dipped and cured at 500 C.

[0220] For this purpose, the glass piece was first provided with a three-layer Sol-Gel coating in the embodiment of a medium refractive, high refractive and low refractive layer-system with the aforementioned properties. Then it was prestressed in a potassium-containing salt melt. The surface was subsequently activated and immediately thereafter provided with an amphiphobic coating.

[0221] The layers wee specifically produced as follows:

[0222] Production of Stock Solution SiO.sub.2:

103 ml tetra-ethoxy-silane were added to 218 ml ethanol. The solution was then mixed with 65 ml H.sub.2O and hydrolyzed with acetic acid. The solution was subsequently mixed with 608 ml ethanol and stopped with hydrochloric acid. This stock solution could be used directly as coating solution.

[0223] Production of Stock Solution TiO.sub.2 (Amorphous):

109 g of an amorphous TiO.sub.2 precursor powder was added to 802 g ethanol and 89 g 15 pentanediol.

[0224] For the synthesis of the TiO.sub.2 precursor powder, 1 mol titanium-tetra-ethylate was mixed with 1 mol acetylacetone and was subsequently hydrolyzed with 5 mol H.sub.2O. P-toluene sulfonic acid could optionally be added to the hydrolysis water. After removal of the solvent, the powder was dried for five hours at 125 C. The amorphous precursor powder had a titanium oxide content of approximately 58 weight-%.

1. Solutionmedium refractive layer
Coating solution C comprised a mixture of stock solution SiO.sub.2 and stock solution TiO.sub.2 (amorphous) at a ratio of weight-% of the oxides of 75:25.
2. Solutionhigh refractive layer

Stock Solution TiO.SUB.2..

[0225] 3. Solutionlow refractive layer
While stirring, 60.5 ml silicic acid tetra-ethyl-ester, 30 ml distilled water and 11.4 g 1M nitric acid were added to 125 ml ethanol. After the addition of water and nitric acid, the solution was stirred for 10 minutes, whereby the temperature did not exceed 40 C. If required, the solution had to be cooled. The solution was then diluted with 675 ml ethanol. After 24 hours, 10.9 g Al(NO.sub.3).sub.39 H.sub.2O, dissolved in 95 ml ethanol and 5 ml acetylacetone were added to this solution.

[0226] For the first Sol-Gel layer that was applied directly onto the suitable glass substrate, coating solution 1 was applied. The applied Sol-Gel layer was dried for 15 minutes at 125 C. and cured. Subsequently, a Sol-Gel layer from coating solution 2 was applied and dried. Then, a Sol-Gel layer from coating solution 3 was applied and again dried.

[0227] After drying of the last applied layer, the thereby obtained layer package was cured for 15 minutes at 470 C.

[0228] The results are summarized in the following table 1:

TABLE-US-00011 TABLE 1 Contact angle measurement in [] Surface after 504 h stress Before NSS- neutral salt-spray Glass Activation [mN/m] Test test (NSS) 1. Soda lime-silicate 38 115 70 glass prestressed 2. Aluminosilicate glass 40 117 68 prestressed 3. Soda lime-silicate 42 115 95 glass with functional layers prestressed 4. Aluminosilicate 40 114 96 glass with functional layers prestressed 5. Soda lime-silicate Aqueous potassium- 58 116 115 glass phosphate solution with functional layers pH 10.5; 2 min @ 50 C. not prestressed aqueous citric acid solution pH 2.5; 2 min@ 40 C. Deionized water 0.5 min@ 20 C. 6. Aluminosilicate glass Aqueous potassium- 58 118 116 with functional layers phosphate solution not prestressed pH 10.5; 2 min @ 50 C. aqueous citric acid solution pH 2.5; 2 min@ 40 C. Deionized water 0.5 min@ 20 C. 7. Soda lime-silicate Aqueous potassium- 58 115 115 glass phosphate solution with functional layers pH 10.5; 2 min @ 50 C. prestressed aqueous citric acid solution pH 2.5; 2 min@ 40 C. Deionized water 0.5 min@ 20 C. 8. Aluminosilicate glass Aqueous potassium- 56 117 116 with functional layers phosphate solution prestressed pH 10.5; 2 min @ 50 C. aqueous-citric acid solution pH 2.5; 2 min@ 40 C. Deionized water 0.5 min@ 20 C. 9. Soda lime-silicate Deionized water 58 115 110 glass 30 min @ 60 C. with functional layers prestressed 10. Aluminosilicate Deionized water 58 115 113 glass 30 min @ 60 C. with functional layers prestressed 11. Soda lime-silicate Ultrasound cleaning: 30-40 kHz 60 116 113 glass with aqueous sodium functional layers hydroxide solution not prestressed pH 10.8; 10 min @ 60 C. Deionized water 2 min@ 20 C. 12. Aluminosilicate Ultrasound cleaning: 30-40 kHz 60 117 116 glass aqueous sodium with functional layers hydroxide solution prestressed pH 10.8; 10 min @ 60 C. Deionized water 2 min@ 20 C. In table 1: Glasses # 1 and 2 did not have functional layer, were not activated, but are prestressed. Glasses # 3 and 4 have functional layers, were not activated, but are prestressed. Glasses # 5 and 6 have functional layers, were activated, but are not prestressed. Glasses # 7 to 12 have functional layers, were activated and are prestressed, i.e., are glass substrates produced according to the present invention.

[0229] In the examples, the antireflective coating and the anti-fingerprint coating applied thereupon are simply referred to as functional layers.

[0230] Above table 1 illustrates that the glass substrates produced according to the present invention (#7 to 12) show practically no change in the contact angle after 504 hours test time, whereas the glass substrates that are not produced according to the present invention (#1 to 4) have clear changes in the contact angle. Glass substrates #5 and 6, which are not produced according to the present invention, are not chemically prestressed and are therefore not scratch resistant and break resistant to the desired extent. The contact angle serves as a measure of whether or not the properties can be maintained following a stress test in the form of the neutral salt spray test. The NSS test is known to be one of the most critical tests for such stresses. It reflects the stresses that occur, for example, during touching with fingerprints. The salt content of the finger sweat is a typical influence for layer failure. The long-term durability is a crucial characteristic for this.

[0231] As demonstrated by the consistent contact angle, as determined within the scope of the measurement accuracy, the activation process according to the present invention provides the glass substrates with a clear improvement of the long-term durability that are not obtained with known glass substrates.

[0232] With the above glass substrates, the values for the compressive stress (CS) and the depth of penetration (DoL) were moreover determined with measuring device FSM6000 based on the optical properties of the glass plates. The CS- and DoL value were measured for 5 samples and the average value was used. In table 2 below, the values are stated and a comparison regarding the visual degree of reflection pvA is given.

TABLE-US-00012 TABLE 2 CS [MPa] CS [MPa] DoL [m] DoL [m] R [%] R [%] Before After Before After Before After Glass # activation activation activation activation activation activation 7 432 (+/4) 438 (+/6) 12.2 (+/0.9) 12.1 (+/0.7) 0.73 0.72 8 755 (+/8) 754 (+/6) 35 (+/2.1) 35 (+/1.1) 0.76 0.75 9 444 (+/6) 443 (+/8) 11.9 (+/0.5) 12.0 (+/0.6) 0.69 0.65 10 751 (+/6) 749 (+/8) 33 (+/1.1) 33 (+/0.7) 0.81 0.80 11 439 (+/3) 441 (+/4) 12.2 (+/0.9) 12.1 (+/0.7) 0.71 0.72 12 750 (+/2) 753 (+/6) 36 (+/1.7) 36 (+/1.1) 0.79 0.78

[0233] The values in Table 2 demonstrate that chemical prestressing, characterized by the compressive stress (CS) and the depth of penetration (DoL), is not being negatively influenced by the activation process; the beneficial properties of the glass substrates remain intact. The values of the degree of reflection before and after activation moreover show that also the beneficial optical properties were not negatively affected by the activation process.

[0234] The present invention therefore provides a coated glass substrate within a unique combination of properties.

[0235] While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.