FLAT GLASS PANE

Abstract

The invention relates to a flat glass pane made of a base material, which is an alkali-containing silicate glass. The flat glass pane is characterized in that at least one surface layer is enriched with potassium and is depleted of sodium and/or lithium while an inner layer, in particular an inner layer directly adjoining the surface layer, is not enriched with potassium and is not depleted of sodium and/or lithium; and the flat glass pane has a compressive stress up to a compressive stress depth and a tensile stress starting from the compressive stress depth, wherein the tensile stress increases as the depth increases up to a tensile stress maximum arranged in the inner layer, and/or the curve of the tensile stress does not have a linear section depending on the depth, and/or the curve of the tensile stress does not have a section in which the tensile stress is constant depending on the depth.

Claims

1. A flat glass pane (7) which is made of a base material which is an alkali-containing silicate glass, or is an aluminosilicate glass, characterized in that a. at least one surface layer (10) is enriched in potassium and depleted in sodium and/or lithium, while an inner layer (11), more particularly an inner layer (11) directly bordering the surface layer (10), is not enriched in potassium and not depleted in sodium and/or lithium, and in that b. the flat glass pane (7), down to a compressive stress depth (2), has a compressive stress (3) and beyond the compressive stress depth (2) has a tensile stress (4), where the tensile stress (4) rises with increasing depth up to a tensile stress maximum disposed in the inner layer (11) and/or where the profile of the tensile stress (4) as a function of the depth has no linear portion and/or where the profile of the tensile stress (4) as a function of the depth has no portion in which the tensile stress (4) is constant.

2. The flat glass pane (7) as claimed in claim 1, characterized in that the surface layer (10) has a thickness in the range from 0.5 μm to 60 μm, more particularly in the range from 0.5 μm to 30 μm, more particularly in the range from 0.5 μm to 15 μm.

3. The flat glass pane (7) as claimed in claim 1, characterized in that the flat glass pane (7) has two surface layers (10), which more particularly are parallel to one another, and in that a. each of the two surface layers (10) is enriched in potassium and depleted in sodium and/or lithium, while an inner layer disposed between the surface layers (10) is not enriched in potassium and not depleted in sodium and/or lithium, and in that b. the flat glass pane (7) on each of both sides, down to a compressive stress depth, has a compressive stress (3) and beyond the compressive stress depth (2) has a tensile stress (4), where the tensile stress (4) rises with increasing depth up to a tensile stress maximum disposed in the inner layer (11) and/or where the profile of the tensile stress (4) as a function of the depth has no linear portion and/or where the profile of the tensile stress (4) as a function of the depth does not have a portion in which the tensile stress (4) is constant.

4. The flat glass pane (7) as claimed in claim 1, characterized in that the tensile stress maximum is disposed centrically between the surface layers (10).

5. The flat glass pane (7) as claimed in claim 1, characterized in that the tensile stress maximum is disposed eccentrically between the surface layers (10).

6. The flat glass pane (7) as claimed in claim 1, characterized in that the flat glass pane (7) has two surface layers (10), which more particularly are parallel to one another, and in that a. only a first of the two surface layers (10) is enriched in potassium and depleted in sodium and/or lithium, while the other surface layer (8) and an inner layer (11) disposed between the surface layers (10) are not enriched in potassium and not depleted in sodium and/or lithium, and in that b. the flat glass pane (7), more particularly on each of both sides, down to a compressive stress depth (2) has a compressive stress (3) and beyond the compressive stress depth (2) has a tensile stress (4), where the tensile stress (4) rises with increasing depth up to a tensile stress maximum disposed in the inner layer and/or where the profile of the tensile stress (4) as a function of the depth has no linear portion and/or where the profile of the tensile stress (4) as a function of the depth does not have a portion in which the tensile stress (4) is constant.

7. The flat glass pane (7) as claimed in claim 6, characterized in that the tensile stress maximum is disposed eccentrically between the surface layers (10)

8. The flat glass pane (7) as claimed in claim 1, characterized in that the flat glass pane has a thickness in the range from 0.03 mm to 22 mm, more particularly in the range from 0.5 mm to 10 mm or from 0.5 mm in the range to 5 mm or in the range from 0.6 mm to 3 mm or in the range from 0.68 mm to 3 mm or of 0.68 mm or in the range from 1.5 mm to 3 mm, or in that the flat glass pane has a thickness of more than 1.5 mm.

9. The flat glass pane (7) as claimed in claim 1, characterized in that the strength, more particularly a strength measured in accordance with DIN EN 1288-5, of the flat glass pane is at least 1.5 times, more particularly at least twice or at least three times or at least four times or at least five times, higher than the strength of an identical flat glass pane, more particularly of a flat glass pane of identical shape and size and identical base material, that does not have the features of the characterizing clause of claim 1.

10. The flat glass pane (7) as claimed in claim 1, characterized in that the surface layer (10) has an increased hardness by comparison with the inner layer (11) and/or in that the surface layer (10) has a Martens hardness, more particularly measured in accordance with DIN EN ISO 14577-1 under a test force of 2 N, in the range from 3500 N/mm.sup.2 to 3900 N/mm.sup.2, more particularly in the range from 3650 N/mm.sup.2 to is 3850 N/mm.sup.2.

11. The flat glass pane (7) as claimed in claim 1, characterized in that in the surface layer (10) the fraction of potassium down to a depth in the range from 0.5 μm to 10 μm is greater than the total fraction of sodium and lithium and in that the fraction of potassium beyond a depth in the range from 0.5 μm to 10 μm is smaller than the total fraction of sodium and lithium.

12. The flat glass pane (7) as claimed in claim 1, characterized in that the depletion of sodium and/or lithium in the potassium-enriched surface layer down to a depth of at least one quarter of the thickness of the surface layer is at least 50% (percent by mass).

13. The flat glass pane as claimed in claim 1, characterized in that the flat glass pane is a float glass pane or a rolled glass pane or drawn glass.

14. The flat glass pane as claimed in claim 1, characterized in that the flat glass pane is embodied as a window pane or as a display pane or as a motor vehicle pane or as a sliding roof pane or as a solar glass pane or as a greenhouse pane.

15. The flat glass pane as claimed in claim 1, characterized in that the glass material is an alkali metal-alkaline earth metal silicate glass, especially a soda-lime glass, or a borosilicate glass.

16. A display, more particularly computer display or mobile phone display, which comprises a flat glass pane as claimed in any of claim 1.

17. An electronic device, more particularly computer or tablet or mobile phone, which comprises a display as claimed in claim 16.

18. A motor vehicle which comprises a flat glass pane as claimed in claim 1.

19. The motor vehicle as claimed in claim 18, characterized in that the flat glass pane is a windshield pane or a tailgate pane or a side pane or a roof pane, more particularly of a glass roof or of a sliding glass roof or of an opening glass roof.

Description

BRIEF DESCRIPTION OF THE DRAWING VIEWS

[0044] In the drawing, the subject matter of the disclosure is represented illustratively and schematically and is described below with reference to the figures, where elements that are identical or identical in effect are usually provided with the same reference signs, even in different exemplary embodiments. Here:

[0045] FIG. 1 shows a schematic representation, not true to scale, of a first component of the stress profile 1 within a flat glass pane of the disclosure,

[0046] FIG. 2 shows a schematic representation, not true to scale, of a second component of the stress profile 1 within a flat glass pane of the disclosure,

[0047] FIG. 3 shows a first exemplary embodiment of a flat glass pane of the disclosure, and

[0048] FIG. 4 shows a second exemplary embodiment of a flat glass pane of the disclosure.

DETAILED DESCRIPTION

[0049] FIG. 1 shows a schematic representation, not true to scale, of a first component of the stress profile 1 within a flat glass pane of the disclosure that has a thickness 6. The first component of the stress profile 1 derives from the fact that initially a flat glass pane blank is produced and is heated to a primary temperature which lies at most 50 kelvins below and at most 30 kelvins above the Littleton softening point of the glass material, and is subsequently quenched to a quenching temperature which lies at least 200 kelvins and at most 550 kelvins, more particularly at least 200 kelvins and at most 450 kelvins, below the primary temperature.

[0050] In the diagram the compressive stress 3 increases, starting from the dashed zero line, toward the right, while the tensile stress 4 increases, starting from the dashed zero line, toward the left.

[0051] It is apparent that the flat glass pane 7, on each of both sides, has a compressive stress 3 which decreases toward the inside and which transitions into a tensile stress 4, which increases up to the center between the outer sides; the profile of the tensile stress as a function of the depth does not have a linear portion and as a function of the depth does not have a portion in which the tensile stress 4 is constant. In the center between the outer sides, the first component has a maximum 5 of tensile stress 4.

[0052] The first component of the stress profile 1 represented in FIG. 1, within the flat glass pane 7, is joined, reinforcing the strength of the flat glass pane 7, by a second component of the stress profile 1 within the flat glass pane, as is represented schematically in FIG. 2.

[0053] FIG. 2 shows a schematic representation, not true to scale, of a second component of the stress profile 1 within the flat glass pane, this component deriving from the fact that the two surface layers 10 are enriched in potassium and depleted in sodium and/or lithium, while the inner layer 11 directly bordering the surface layers 10 is not enriched in potassium and not depleted in sodium and/or lithium. It is apparent that the stress profile 1 of the second component in the inner layer 11 is very largely linear.

[0054] Both the first component and the second component contribute to the strength of the flat glass pane. The stress profile effective overall is therefore determined jointly by the first component and the second component, and so ultimately on each of both sides, the flat glass pane has a compressive stress 3 down to a compressive stress depth 2 and beyond the compressive stress depth 2 has a tensile stress 4, where the tensile stress 4 rises with increasing depth up to a tensile stress maximum 5 disposed in the inner layer 11 and/or where the profile of the tensile stress 4 as a function of the depth does not have a linear portion and/or where the profile of the tensile stress 4 as a function of the depth does not have a portion in which the tensile stress 4 is constant.

[0055] FIG. 3, in a cross-sectional representation, shows a first exemplary embodiment of a flat glass pane 7, which has a planar embodiment. In the enlarged representation 9 of a detail of the flat glass pane 7, the flat glass pane 7 is shown to have, on each of both sides, a surface layer 10 which is enriched in potassium and depleted in sodium and/or lithium, while an inner layer 11, more particularly directly bordering the surface layer 10, is not enriched in potassium and not depleted in sodium and/or lithium. The flat glass pane 7 has a stress profile 1 which results from the simultaneous effect of the two components represented in FIGS. 1 and 2.

[0056] FIG. 4, in a cross-sectional representation, shows a second exemplary embodiment of a flat glass pane 7 of the disclosure, which has a curved embodiment. In the enlarged representation 9 it is shown that the flat glass pane 7 has on one side a surface layer 10 which is enriched in potassium and depleted in sodium and/or lithium, while an inner layer 11, more particularly directly bordering the surface layer 10, and also the other surface layer 12 are not enriched in potassium and not depleted in sodium and/or lithium. In the case of this exemplary embodiment, the flat glass pane 7 exhibits an asymmetric stress profile 1, deriving from two asymmetric components, with the tensile stress maximum being disposed eccentrically between the outer sides of the flat glass pane 7.

LIST OF REFERENCE SIGNS

[0057] 1 Stress profile [0058] 2 Compressive stress depth [0059] 3 Compressive stress [0060] 4 Tensile stress [0061] 5 Tensile stress maximum [0062] 6 Thickness [0063] 7 Flat glass pane [0064] 8 Other surface layer [0065] 9 Enlarged representation [0066] 10 Surface layer [0067] 11 Inner layer