GLARE-FREE GLASS ARTICLES AND METHOD FOR PRODUCING GLARE-FREE GLASS ARTICLES

Abstract

Glare-free glass articles and methods for producing are provided. The glass article includes a surface with an area having a roughness RMS from 10 nm to 1000 nm, a distinctness of image DOI from 30 to 70, a gloss value of less than 40 at a viewing angle of 60°, and a haze value, determined in transmission, of less than 3%. The area also has a ratio of mean height of peaks above core surface (Spk) to mean depth of valleys below core surface (Svk) that is equal to 1±0.1 within a measured surface area of more than 0.1 mm.sup.2 and less than 3 mm.sup.2.

Claims

1. A sheet-like glass article, comprising: a surface with an area having a roughness RMS from 10 nm to 1000 nm, a distinctness of image DOI from 30 to 70, a gloss value of less than 40 at a viewing angle of 60°, and a haze value, determined in transmission, of less than 3%; and a ratio of mean height of peaks above core surface (Spk) to mean depth of valleys below core surface (Svk) determined for the area that is equal to 1±0.1 within a measured surface area of more than 0.1 mm.sup.2 and less than 3 mm.sup.2.

2. The article of claim 1, wherein the area further comprises a skewness value (Ssk) that is greater than 0 determined within the measured surface area.

3. The article of claim 1, wherein the area further comprises a root mean square gradient value (Sdq) that is at least 50 μm/mm over a surface area of 0.33 mm*0.33 mm.

4. The article of claim 3, wherein the root mean square gradient value (Sdq) is at least 75 μm/mm over the surface area of 0.33 mm*0.33 mm.

5. The article of claim 3, wherein the root mean square gradient value (Sdq) is at least 70 μm/mm over an area of 1.6 mm*1.6 mm.

6. The article of claim 3, wherein the root mean square gradient value (Sdq) is at least 100 μm/mm over an area of 1.6 mm*1.6 mm.

7. The article of claim 1, wherein the area has a surface topography configured so that a skewness or asymmetry (Ssk) is greater than 0.

8. The article of claim 7, wherein the skewness or asymmetry (Ssk) is more than 1.

9. The article of claim 1, further comprising a sparkle, as determined for a display having 190 DPI, of less than 0.1.

10. The article of claim 9, wherein the sparkle is at most 0.09.

11. The article of claim 1, wherein the glass article is toughened.

12. The article of claim 1, wherein the glass article is chemically toughened.

13. The article of claim 1, further comprising a thickness between 0.1 mm and 8 mm.

14. The article of claim 1, wherein the glass article comprises glass comprising, in wt %: TABLE-US-00005 SiO.sub.2 50 to 80, Al.sub.2O.sub.3 0 to 30, B.sub.2O.sub.3 0 to 20, Li.sub.2O 0 to 15, Na.sub.2O 0 to 20, K.sub.2O 0 to 20, CaO 0 to 15, BaO 0 to 10.

15. A method for producing a sheet-like glass article, comprising: cleaning a surface of a glass sheet; applying a hydrophobizing liquid to an area of the surface so that the area has a contact angle of more than 90°; masking the area using a solution of a surface-active agent so that, in the area, droplets of the solution having a mean diameter between at least 1 m and at most 100 m are provided; and plasma etching the area using a fluorine-containing reactive gas so that the area has a roughness RMS from 10 nm to 1000 nm, a distinctness of image DOI from 30 to 70, a gloss value of less than 40 at a viewing angle of 60°, a haze value, determined in transmission, of less than 3%, and a ratio of mean height of peaks above core surface (Spk) to mean depth of valleys below core surface (Svk) that is equal to 1±0.1 within a measured surface area of more than 0.1 mm.sup.2 and less than 3 mm.sup.2.

16. The method of claim 15, wherein the step of applying the hydrophobizing liquid comprises spraying the hydrophobizing liquid and/or wherein the step of masking the area using the solution comprises spraying the solution.

17. The method of claim 15, wherein the hydrophobizing liquid comprises an alkyl perfluorocarbon silane of formula (Rf).sub.xSiX.sub.4-x, where Rf is selected from a group consisting of: a linear C.sub.6 to C.sub.30 alkyl perfluorocarbon and X is Cl or —OCH.sub.3, and x assumes values between 2 and 4, a fluoroalkyl oligosiloxane, a fluoroalkyl siloxane, a fluoroalkyl oligosiloxane, and an ethanolic solution of a fluoroalkyl oligosiloxane.

18. The method of claim 15, wherein the solution is selected from a group consisting of: an anionic surface-active agent in ethanol, an anionic surface-active agent in glycol ether, and an anionic surface-active agent in glycol ether with a concentration of the anionic surface-active agent of at least 5 wt % and at most 20 wt % based on the total weight of the solution.

19. The method of claim 15, wherein the fluorine-containing reactive gas comprises a gas comprising a compound selected from a group consisting of: CF.sub.4, CHF.sub.3, C.sub.4F.sub.8, SF.sub.6, and any combinations thereof.

20. The method of claim 15, wherein the plasma etching comprises a process selected from a group consisting of: microwave plasma etching, RF plasma etching, and reactive ion beam etching.

21. The method of claim 15, wherein the reactive gas is CF.sub.4 and the plasma etching is microwave plasma etching at a pressure of 10 mbar.

22. The method of claim 15, wherein the reactive gas is CF.sub.4 and the plasma etching is RF plasma etching at a pressure of 0.5 mbar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0114] FIGS. 1a and 1b show photographs of the surfaces of glass articles that have been masked;

[0115] FIGS. 2a and 2b show photographs of hydrophobized and then masked surfaces of glass articles;

[0116] FIGS. 3a-3c show photographs of etched surfaces of glass articles;

[0117] FIGS. 4a-4f show views of surface topographies of glass articles as obtained by white light interferometry in each case; and

[0118] FIG. 5 is a schematic diagram of a glass article according to one embodiment, not drawn to scale.

DETAILED DESCRIPTION

[0119] The invention will now be further discussed by way of examples.

Example 1

[0120] A glass article comprising aluminosilicate glass as commercially available under the designation AS 87 was first cleaned in an industrial dishwasher in order to clean the surfaces of the glass article from dirt such as grease, fingerprints, or the like. Then, a 0.25 wt % solution of a modified fluoroalkyl oligosiloxane in ethanol (1 g of fluoroalkyl oligosiloxane in 395 g of ethanol) was applied over the entire surface of the glass article. In this way, a surface of the glass article was made hydrophobic. More generally, without being limited to the example specifically described here, it is also possible that only an area of the at least one surface of the glass article is made hydrophobic, for example by covering the area or areas of the at least one surface, which are not intended to be hydrophobized. Subsequently, a 5% solution of a surfactant in ethanol and a mixture of different glycol ethers was applied to the hydrophobized surface of the glass article by spraying. Then, plasma etching was performed in a CF.sub.4-containing atmosphere in a microwave plasma at a pressure of 10 mbar.

Example 2

[0121] A glass article comprising a lithium aluminum silicate glass as commercially available under the designation LAS 80 was first cleaned in an industrial dishwasher in order to clean the surfaces of the glass article from dirt such as grease, fingerprints, or the like. Then, a 0.25 wt % solution of a modified fluoroalkyl oligosiloxane in ethanol (1 g of fluoroalkyl oligosiloxane in 395 g of ethanol) was applied over the entire surface of the glass article. In this way, a surface of the glass article was made hydrophobic. Subsequently, a 5% solution of a surfactant in ethanol and a mixture of different glycol ethers was applied to the hydrophobized surface of the glass article by spraying. Then, plasma etching was performed in a CF.sub.4-containing atmosphere in a microwave plasma at a pressure of 10 mbar.

[0122] Again, it is generally possible here that the at least one surface is not hydrophobized over its entire surface area, but only in an area of the surface.

Example 3

[0123] A glass article comprising aluminosilicate glass as commercially available under the designation AS 87 was first cleaned in an industrial dishwasher in order to clean the surfaces of the glass article from dirt such as grease, fingerprints, or the like. Then, a 0.25 wt % solution of a modified fluoroalkyl oligosiloxane in ethanol (1 g of fluoroalkyl oligosiloxane in 395 g of ethanol) was applied over the entire surface of the glass article. In this way, a surface of the glass article was made hydrophobic. Subsequently, a 5% solution of a surfactant in ethanol and a mixture of different glycol ethers was applied to the hydrophobized surface of the glass article by spraying. Then, plasma etching was performed in a CF.sub.4-containing atmosphere in an RF plasma at a pressure of 0.5 mbar.

[0124] Again, it is generally possible here that the at least one surface is not hydrophobized over its entire surface area, but only in an area of the surface.

Example 4

[0125] A glass article comprising a lithium aluminum silicate glass as commercially available under the designation LAS 80 was first cleaned in an industrial dishwasher in order to clean the surfaces of the glass article from dirt such as grease, fingerprints, or the like. Then, a 0.25 wt % solution of a modified fluoroalkyl oligosiloxane in ethanol (1 g of fluoroalkyl oligosiloxane in 395 g of ethanol) was applied over the entire surface of the glass article. In this way, a surface of the glass article was made hydrophobic. Subsequently, a 5% solution of a surfactant in ethanol and a mixture of different glycol ethers was applied to the hydrophobized surface of the glass article by spraying. Then, plasma etching was performed in a CF-containing atmosphere in an RF plasma at a pressure of 0.5 mbar.

[0126] Again, it is generally possible here that the at least one surface is not hydrophobized over its entire surface area, but only in an area of the surface.

Example 5

[0127] A glass article comprising a lithium aluminum silicate glass as commercially available under the designation LAS 80 was first cleaned in an industrial dishwasher in order to clean the surfaces of the glass article from dirt such as grease, fingerprints, or the like. Then, 1 ml of alkyl perfluorocarbon silane (e.g. trichloro(1H,1H,2H,2H-perfluorooctyl)silane) was applied. In this way, a surface of the glass article was made hydrophobic over the entire surface area. Subsequently, a solution of a surfactant in ethanol and a mixture of different glycol ethers was applied to the hydrophobized surface of the glass article by spraying. Then, plasma etching was performed in a CF-containing atmosphere in an RF plasma at a pressure of 0.5 mbar.

[0128] Again, it is generally possible here, that the at least one surface is not hydrophobized over its entire surface area, but only in an area of the surface.

[0129] FIG. 1a shows the photograph of a surface of a glass article that has been masked without previously having been hydrophobized. When a masking solution is applied, a few relatively large “islands” are resulting, with an average diameter of more than 1 mm, and adjacent thereto relatively large non-covered surface areas. This does not allow to achieve a visually inconspicuous uniform matting of a surface of a glass article, which would result in a reduction in glare of a display.

[0130] For identification of the dimensions, the scale labeled 1000 mm is indicated in the upper right corner of FIG. 1a, and the diameter of 1099.08 μm of one “island” is also indicated.

[0131] FIG. 1b, by contrast, is a photograph that shows of a surface of a glass article which was masked only after having been hydrophobized. In this way, a uniform distribution of the masking liquid or masking solution is obtained in the form of droplets with a diameter between 1 μm and 100 μm, depending on the precise spray parameters selected.

[0132] Here, two diameters of such finer applied texture features are indicated, next to the scale, in the upper right corner of FIG. 1b.

[0133] FIGS. 2a and 2b show the photographs of surfaces of glass articles which were masked after having been hydrophobized in each case. The masking shown in FIG. 2a was obtained using a hand spray gun, and the masking shown in FIG. 2b was obtained using an automatic spraying system. As can be seen, both the manual spray application and the automated spraying process in a spray-coating system lead to an even distribution of the masking solution in the form of small droplets with a diameter between 1 μm and 100 μm, and for two texture features the respective diameter is indicated. The scale is indicated at the top right.

[0134] FIGS. 3a-3c show photographs of etched surfaces of glass articles according to embodiments. The surfaces were etched for different lengths of time. The sample in FIG. 3a results from the etching step being performed for 60 seconds, in FIG. 3b for 150 seconds, and in FIG. 3c for 300 seconds.

[0135] Finally, FIGS. 4a-4f shows a comparison of surface topographies of commercially available surfaces of glass articles as obtained by wet chemical etching (FIGS. 4a and 4b) exhibiting rather large irregular texture features, in particular comprising circular or spherical dome-shaped dents. FIGS. 4a and 4b were obtained for a measured area of 0.336*0.336 mm.sup.2, whereby the same area was measured in each case, but view FIG. 4b is slightly tilted in comparison to FIG. 4a, in order to represent the topography more distinctively.

[0136] By contrast, surface topographies FIGS. 4c and 4d exhibit significantly finer and more evenly distributed texture features. FIGS. 4c and 4d were obtained for a measured area of 0.336*0.336 mm.sup.2, whereby the same area was measured in each case, but FIG. 4d is slightly tilted in comparison to FIG. 4c, in order to represent the topography more distinctively.

[0137] Finally, FIGS. 4e and 4f show measurements of surface topographies in the at least one area.

[0138] The surfaces or parameters characterizing the surfaces were determined in each case on a surface area of 0.336*0.336 mm.sup.2 (FIG. 4 a-d) or for a larger surface area of 1.6*1.6 mm.sup.2 (FIGS. 4e and 4f).

[0139] This difference between the illustrated surfaces of embodiments of the glass article can be seen from the surfaces of FIGS. 4c and 4d, as shown here by way of example, have an Ssk of greater than 0, preferably greater than 1, and a ratio of Spk to Svk equal to 1±0.1, determined for the at least one surface within a measured surface area of more than 0.1 mm.sup.2 and less than 3 mm.sup.2.

[0140] Measured values of surface parameters that further demonstrate the differences in topographies are shown in the tables below.

[0141] For an exemplary sample which is wet-chemically etched and has the typical structures obtained by wet chemical etching, and for a typical sample according to one embodiment of the present disclosure, the following values are obtained for the at least one area of the at least one surface:

TABLE-US-00002 Size of measured surface area 1.6*1.6 mm.sup.2 0.33*0.33 mm.sup.2 1.6*1.6 mm.sup.2 0.33*0.33 mm.sup.2 (FIG. 4 e) (FIG. 4 a, b) (FIG. 4 f) (FIG. 4 c, d) Sk (nm) 565 551 750 605 Spk (nm) 148 70 301 226 Svk (nm) 310 335 290 212 Spk/Svk 0.48 0.21 1.04 1.07

[0142] This effect of the difference in the measured values or values for characterizing the surface in the at least one area of the at least one surface is thereby shown to be independent of the size of the examined area, as can be seen from the above measurements by way of example.

[0143] The skewness of the surface of the reference sample as well as of the at least one region of the at least one surface according to the present application also differs, as can be seen from the following comparison:

TABLE-US-00003 Prior art (Ssk) Embodiment of present disclosure (Ssk) −0.2 to −0.9 0.03 to 0.13

[0144] Ssk refers to the skewness of the surface area as it is defined above.

[0145] In other words—as can also be seen from the surface topographies depicted in FIGS. 4a-4f—the surface structures of samples according to the prior art are dominated by “valley structures” or depressions, whereas the samples obtained according to embodiments of the present disclosure have a different configuration in the at least one area of the at least one surface, namely, as exemplified by the above measurement, dominated by peaks. This also applies independently of the size of the examined measured area. However, these are always smaller than 0 regardless of the size of the measurement area. In contrast, for the embodiments according to the present disclosure, values in the range between 0.03 and 0.13 are obtained, i.e.,—regardless of the size of the measured area—always values greater than 0.

[0146] Finally, the following table shows the parameter Sdq and the roughness RMS in the at least one region of the at least one surface:

TABLE-US-00004 Size of measured surface area 1.6*1.6 0.33*0.33 1.6*1.6 0.33*0.33 mm.sup.2 mm.sup.2 mm.sup.2 mm.sup.2 Sdq (μm/mm) 55 34 108 81 Roughness RMS 231 232 298 235 (nm)

[0147] In other words, the root mean square gradient of the surface topographies according to embodiments of the present disclosure in the at least one region of the at least one surface is greater than for surface topographies obtained by known methods. This is because the structures according to embodiments of the present disclosure are laterally narrower.

[0148] The above measurement values were obtained in accordance with ISO 25178 for three-dimensional surface profiles or in accordance with ISO 13565-2, which describes analogous values for essentially two-dimensional sections.

[0149] For larger surface areas, i.e., of 1.6*1.6 mm.sup.2, corresponding views of the surface topographies can be found in FIGS. 4e and 4f.

[0150] Finally, FIG. 5 shows a schematic diagram of a sheet-like glass article 1 according to one embodiment, not drawn to scale.

[0151] Here, the glass article 1 comprises two main faces or surfaces 11 and 12 which may also be considered as an upper surface (surface 11) and a lower surface (surface 12), here. Surface 11 includes an area 101 with a roughness RMS from 10 nm to 1000 nm, preferably a DOI from 30 to 70, a gloss value of more than 40 at a viewing angle of 60°. In a portion 110 which includes the area 101 of the at least one surface 11, the glass article has a haze value, determined in transmission, of less than 3%.

[0152] The ratio of Spk to Svk, determined for the at least one area 101 of the at least one surface 11, is equal to 1±0.1 within a measured surface area of more than 0.1 mm.sup.2 and less than 3 mm.sup.2, and/or the Ssk value, determined for the at least one area 101 of the at least one surface 11 of the glass article 1 is greater than 0, preferably determined within a measured surface area of more than 0.1 mm.sup.2 and less than 3 mm.sup.2, and/or the root mean square gradient value, Sdq, of the at least one area 101 of the at least one surface 11 is at least 50 μm/mm, preferably at least 75 μm/mm over a surface area of 0.33 mm*0.33 mm, and/or is at least 70 μm/mm, preferably at least 90 μm/mm, and most preferably at least 100 μm/mm over a surface area of 1.6 mm*1.6 mm.

[0153] The glass article 1 includes at least one further area 102 on the surface 11, in which the glare of the surface was not reduced and where, consequently, special surface features or surface topographies or surface texture as in area 101 were not produced.

[0154] The glass article 1 thus comprises a portion 110 in which at least one surface 11, 12 includes an area 101 in which a special surface texture has been produced, and a portion 120 in which no such surface texture has been produced.

LIST OF REFERENCE NUMERALS

[0155] 1 Glass article [0156] 11, 12 Surfaces or main surfaces of the glass article [0157] 101, 102 Surface areas of the glass article [0158] 110, 120 Portions of the glass article