WO2025121366A1 - Glass plate, laminate, and display device - Google Patents

Abstract

The purpose of the present invention is to provide glass capable of improving the light extraction efficiency. The glass plate has a first main surface and a second main surface facing the first main surface, has a thickness of 0.30-1.00 mm, and satisfies formulas (1) and (2) with expression as the mass percentage on an oxide basis.　(1): 0.03 ≤ (ΔSnO₂)_T ≤ 1.0; (2): 0.20 ≤ (ΔSnO₂)_B ≤ 1.5

Description

Glass plate, laminate and display device

The present invention relates to a glass plate, a laminate, and a display device.

Chemically strengthened glass is glass that has been immersed in a molten salt composition such as sodium nitrate to cause an ion exchange between the alkali ions contained in the glass and the alkali ions with a larger ionic radius contained in the molten salt composition, thereby forming a compressive stress layer on the surface of the glass.

Chemically strengthened glass is widely used in applications where strength is required. Examples of such applications include protective materials for display devices such as mobile phones, smartphones, and tablet terminals, building materials such as window glass, table tops, interiors of automobiles and airplanes, and protective materials for these (for example, Patent Document 1).

Chemically strengthened glass has an increased refractive index in the chemically strengthened area. In chemically strengthened glass in which the surface layer is ion-exchanged, the refractive index of light at the surface layer increases and tends to approach the refractive index of light at the center of the plate thickness from the surface layer to the interior (Patent Document 2).

International Publication No. 2019/070005 Japanese Patent Application Publication No. 2012-211051

When chemically strengthened glass with an ion-exchanged surface is used as a protective material for components that have light-emitting elements, such as display devices, there is an issue that the efficiency of extracting light from the light-emitting elements decreases.

The present invention was made in consideration of the above problems, and aims to provide a glass plate that can improve the light extraction efficiency.

The present inventors discovered that the light extraction efficiency can be improved by providing glass with a _SnO2 concentration distribution, and thus completed the present invention.

That is, the present invention is as follows.
1. A semiconductor device having a first main surface and a second main surface opposite to the first main surface,
The thickness is 0.30 to 1.00 mm,
A glass plate satisfying the following formulas (1) and (2) in terms of mass percentage based on oxides.
0.03≦(ΔSnO ₂ ) _T ≦1.0 (1)
0.20≦(ΔSnO ₂ ) _B ≦1.5 (2)
(ΔSnO ₂ ) _T : Value (%) obtained by subtracting [SnO ₂ concentration (%) on the first main surface] from [SnO ₂ concentration (%) on the sheet thickness center]
(ΔSnO ₂ ) _B : Value (%) obtained by subtracting [SnO ₂ concentration (%) at the center of sheet thickness] from [SnO ₂ concentration (%) at the second main surface]
2. The glass plate according to 1, wherein the value obtained by subtracting the _SnO2 concentration (%) at the first main surface from the _SnO2 concentration (%) at a depth of 100 μm from the first main surface is 0 to 0.9%, expressed in mass percentage based on oxide.
3. The glass plate according to 1 or 2, wherein the value obtained by subtracting the _SnO2 concentration (%) at a depth of 100 μm from the second main surface from the _SnO2 concentration (%) in the second main surface is 0.15 to 1.4%, expressed in mass percentage based on oxide.
4. The base composition is expressed as a mass percentage based on oxides.
_SiO2 55-75%,
7.0 to 30% Al ₂ O ₃ ,
4. The glass plate according to any one of 1 to 3 above, containing 0.01 to 13.0% of Li ₂ O.
5. The base composition is expressed as a mass percentage based on oxides.
_SiO2 55-75%,
7.0 to 30% Al ₂ O ₃ ,
0.01 to 13.0% Li ₂ O,
0-18% Na ₂ O,
_ZrO2 from 0.1 to 6.0%,
1.0 to 9.0% Y ₂ O ₃ ,
5. The glass plate according to any one of 1 to 4 above, containing 0 to 5.0% of P ₂ O ₅ .
6. The base composition is expressed as a mass percentage based on oxides.
_SiO2 60-66%,
23-27% Al ₂ O ₃ ,
3.5 to 5.0% Li ₂ O,
1.0-2.0% Na ₂ O,
K ₂ O 0.1 to 0.5%,
_TiO2 0.01-0.2%,
_ZrO2 2.5-3.5%,
5. The glass plate according to any one of 1 to 4 above, containing 0.4 to 1.0% of _SnO2 .
7. The base composition is expressed as a mass percentage based on oxides.
_SiO2 60-66%,
18-24% Al ₂ O ₃ ,
4.0 to 6.0% Li ₂ O,
0.5-1.5% Na ₂ O,
K ₂ O 0.1 to 1.5%,
_TiO2 0.01-0.2%,
_ZrO2 from 2.0 to 3.5%,
5. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of _SnO2 .
8. The base composition is expressed as a mass percentage based on oxides.
_SiO2 56-60%,
25-29% Al ₂ O ₃ ,
4.5 to 7.0% Li ₂ O,
0.3-1.0% Na ₂ O,
K ₂ O 0.1 to 0.5%,
_TiO2 0.01-0.2%,
_ZrO2 2.5-3.5%,
5. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of _SnO2 .
9. The base composition is expressed as a mass percentage based on oxides.
_SiO2 60 to 64%,
20-24% Al ₂ O ₃ ,
3.5-5.5% Li ₂ O,
0.8-1.5% Na ₂ O,
K ₂ O 0.5 to 1.0%,
_TiO2 0.01-0.2%,
_ZrO2 2.5-3.5%,
5. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of _SnO2 .
10. The base composition is expressed as a mass percentage based on oxides.
_SiO2 58-62%,
21-25% Al ₂ O ₃ ,
3.5-5.5% Li ₂ O,
0.5-1.5% Na ₂ O,
K ₂ O 0.3 to 1.5%,
_TiO2 0.01-0.2%,
5. The glass plate according to any one of 1 to 4 above, containing 2.0 to 3.0% of _ZrO2 .
11. The base composition is expressed as a mass percentage based on oxides.
_SiO2 58-62%,
21-25% Al ₂ O ₃ ,
3.5-5.5% Li ₂ O,
0.5-1.5% Na ₂ O,
K ₂ O 0.3 to 1.5%,
_TiO2 0.01-0.2%,
_ZrO2 from 2.0 to 3.5%,
5. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of _SnO2 .
12. The glass plate according to any one of 1 to 5 above, which is made of crystallized glass.
13. The glass plate according to any one of 1 to 12 above, which is a chemically strengthened glass.
14. The glass plate according to any one of 1 to 13 above, which is a float glass.
15. The glass plate according to any one of 1 to 14 above, which has a visible light transmittance of 91.0% or more when converted into a glass plate with a thickness of 0.7 mm.
16. A laminate comprising the glass plate according to any one of 1 to 15 above and a liquid crystal glass plate,
The lamination surface of the glass plate with the liquid crystal glass plate is the second main surface,
a laminate, wherein an absolute value of a difference between a refractive index of the second main surface of the glass plate measured with a prism coupler and a refractive index of the liquid crystal glass plate measured with a prism coupler is 0.001 to 0.20.
17. A display device comprising the glass plate according to any one of 1 to 15 above or the laminate according to 16 above.

The glass plate of the present invention has a refractive index distribution resulting from a specific range of _SnO2 concentration distribution, and therefore can improve the light extraction efficiency. By using the glass plate of the present invention as a protective member for a display device, the light extraction efficiency of the light emitted by the light-emitting element can be improved, and power saving can be achieved.

FIG. 1 is a diagram showing one aspect of the relationship when the horizontal axis represents the depth from the first main surface and the vertical axis represents the _SnO2 concentration in a glass plate according to one embodiment. 2A and 2B are diagrams each showing one aspect of the relationship between the depth from the first main surface of a glass plate according to one embodiment and the _SnO2 concentration. FIG. 3 is a schematic diagram of a glass manufacturing apparatus using the float process.

The glass plate of the present invention will be described in detail below based on the embodiments, but the present invention is not limited to the following embodiments, and can be modified as desired without departing from the gist of the present invention.

In this specification, "chemically strengthened glass" refers to glass after chemical strengthening treatment. Also, "glass for chemical strengthening" refers to glass before chemical strengthening treatment.

In this specification, the glass composition of glass for chemical strengthening is sometimes referred to as the base composition of chemically strengthened glass. In chemically strengthened glass, a compressive stress layer is usually formed on the glass surface due to ion exchange, so the glass composition of the non-ion-exchanged portion matches the base composition of chemically strengthened glass. Furthermore, even in the ion-exchanged portion, the concentration of components other than alkali metal oxides does not fundamentally change when expressed as mole percentage based on oxide. As will be described later, the glass composition in this specification is expressed as mass percentage based on oxide, but the change in glass components before and after ion exchange is based on mole percentage based on oxide.

In this specification, glass compositions are expressed as mass percentages based on oxides, and mass% may be simply written as %. In addition, "~" indicating a numerical range is used to mean that the numerical values written before and after it are included as the lower and upper limits.

<Glass plate>
The glass according to this embodiment has a first principal surface and a second principal surface opposite to the first principal surface, and is characterized in that it has a thickness of 0.30 to 1.00 mm and satisfies the following formulas (1) and (2) in terms of mass percentage based on oxides:
0.03≦(ΔSnO ₂ ) _T ≦1.0 (1)
0.20≦(ΔSnO ₂ ) _B ≦1.5 (2)
(ΔSnO ₂ ) _T : Value (%) obtained by subtracting [SnO ₂ concentration (%) at the first main surface] from [SnO ₂ concentration (%) at the sheet thickness center] (ΔSnO ₂ ) _B : Value (%) obtained by subtracting [SnO ₂ concentration (%) at the sheet thickness center] from [SnO ₂ concentration (%) at the second main surface]

The glass sheet according to this embodiment is preferably a glass sheet (float glass) manufactured by the float method. A float glass sheet has a bottom surface that comes into contact with the molten metal during forming, and a top surface that faces the bottom surface. In this embodiment, when the glass sheet is a float glass sheet, it is preferable that the first main surface is the top surface and the second main surface is the bottom surface.

( _SnO2 concentration)
In the glass plate according to the present embodiment, ( _ΔSnO2 ) _T , which is the value (%) obtained by subtracting [ _SnO2 concentration (%) at the first principal surface] from [ _SnO2 concentration (%) at the plate thickness center], is 0.03% or more and 1.0% or less. By making ( _ΔSnO2 ) _T 0.03% or more and 1.0% or less, a refractive index distribution can be imparted to the glass surface layer of the first principal surface, and the extraction efficiency of light emitted from the plate thickness center of the glass through the first principal surface to the outside can be improved.

From the viewpoint of further increasing the light extraction efficiency, (ΔSnO ₂ ) _T is preferably 0.05% or more, and is preferably 0.07% or more, 0.10% or more, 0.13% or more, 0.15% or more, 0.17% or more, 0.20% or more, 0.23% or more, 0.25% or more, 0.28% or more, or 0.30% or more in the following stepwise manner. In addition, (ΔSnO ₂ ) _T may be 0.40% or more, 0.45% or more, or 0.50% or more. In addition, from the viewpoint of ion exchange efficiency, (ΔSnO ₂ ) _T is preferably 0.90% or less, and is preferably 0.85% or less, 0.80% or less, 0.75% or less, 0.70% or less, 0.65% or less, 0.60% or less, 0.55% or less, or 0.50% or less in the following stepwise manner.

In the glass plate according to the present embodiment, ( _ΔSnO2 ) _B , which is the value (%) obtained by subtracting [ _SnO2 concentration (%) at the center of the plate thickness] from [ _SnO2 concentration (%) at the second main surface], is 0.20% or more and 1.5% or less. By having ( _ΔSnO2 ) _B of 0.20% or more and 1.5% or less, a refractive index distribution is provided in the glass surface layer of the second main surface, and the refractive index is made closer to that of the glass on the surface of the light-emitting component, thereby increasing the efficiency of light capture entering from the second main surface toward the center of the plate thickness, and as a result, the efficiency of light extraction from the first main surface can be improved.

From the viewpoint of further increasing the light extraction efficiency, (ΔSnO ₂ ) _B is preferably 0.25% or more, and is preferably 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, 0.45% or more, or 0.50% or more in the following stepwise manner. Also, (ΔSnO ₂ ) _B may be 0.60% or more, 0.65% or more, or 0.70% or more. Also, from the viewpoint of reducing the deformation amount when heat is applied, (ΔSnO ₂ ) _B is preferably 1.4% or less, more preferably 1.3% or less, even more preferably 1.2% or less, particularly preferably 1.1% or less, and most preferably 1.0% or less.

In the glass plate according to the present embodiment, the value obtained by subtracting the [ _SnO2 concentration (%) at the first main surface] from the [ _SnO2 concentration (%) at a depth of 100 μm from the first main surface] is preferably 0 to 0.9%. By making the value 0 to 0.9%, it is possible to provide a refractive index distribution at the first main surface and further improve the extraction efficiency of light emitted from the center of the glass plate thickness through the first main surface to the outside.

In the glass plate according to the present embodiment, from the viewpoint of further improving the light extraction efficiency, the value obtained by subtracting the [SnO ₂ concentration (%) at the first main surface] from the [SnO ₂ concentration (%) at a depth of 100 μm from the first main surface] is more preferably 0.05% or more, even more preferably 0.1% or more, and particularly preferably 0.2% or more. In addition, the value obtained by subtracting the [SnO ₂ concentration (%) at the first main surface] from the [SnO ₂ concentration (%) at a depth of 100 μm from the first main surface] may be 0.3% or more, or may be 0.4% or more. From the viewpoint of ion exchange efficiency, the value obtained by subtracting the [SnO ₂ concentration (%) at the first main surface] from the [SnO ₂ concentration (%) at a depth of 100 μm from the first main surface] is more preferably 0.8% or less, even more preferably 0.7% or less, particularly preferably 0.6% or less, and most preferably 0.5% or less. In addition, the value obtained by subtracting the [ _SnO2 concentration (%) at the first main surface] from the [ _SnO2 concentration (%) at a depth of 100 μm from the first main surface] may be 0.4% or less, 0.3% or less, or 0.2% or less.
Here, [ _SnO2 concentration (%) on the first principal surface] refers to the average tin oxide concentration in terms of _SnO2 at a depth of 10 μm from the first principal surface.

In the glass plate according to the present embodiment, the value obtained by subtracting the SnO ₂ concentration (%) at a depth of 100 μm from the second main surface from the SnO ₂ concentration (%) is preferably 0.15% or more, and is preferably 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, and 0.40% or more in a stepwise manner. In addition, in the glass plate according to the present embodiment, the value obtained by subtracting the SnO ₂ concentration (%) at a depth of 100 μm from the second main surface from the SnO ₂ concentration (%) is preferably 1.4% or less, and is preferably 1.3% or less, 1.2% or less, 1.0% or less, 0.9% or less, 0.8% or less, and 0.7% or less in a stepwise manner. By having this value within the above numerical range, a refractive index distribution is imparted to the second principal surface, thereby further increasing the efficiency of light capture entering from the second principal surface toward the center of the plate thickness, and as a result, the efficiency of light extraction from the first principal surface can be further improved.
Here, [ _SnO2 concentration (%) on the second principal surface] refers to the average tin oxide concentration in terms of _SnO2 at a depth of 10 μm from the second principal surface.

In the glass plate according to the present embodiment, from the viewpoint of further improving the light extraction efficiency, the value obtained by subtracting [SnO ₂ concentration (%) at a depth of 100 μm from the second main surface] from [SnO ₂ concentration (%) at the second main surface] is preferably 0.15% or more, and is preferably 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, or 0.40% or more in the following stepwise manner. In addition, the value may be 0.5% or more, 0.6% or more, 0.7% or more, or 0.8% or more. From the viewpoint of reducing the amount of deformation when heat is applied, the value obtained by subtracting [SnO ₂ concentration (%) at a depth of 100 μm from the second main surface] from [SnO ₂ concentration (%) at the second main surface] is preferably 1.4% or less, and is preferably 1.3% or less, 1.2% or less, 1.0% or less, 0.9% or less, 0.8% or less, or 0.7% or less in the following stepwise manner.

The _SnO2 concentration can be evaluated by XRF (X-ray Fluorescence Spectrometer). Examples of analysis conditions for the XRF method are as follows:
The amount can be determined by a calibration curve method using glass containing _SnO2 as a standard sample. The measurement device can be ZSX100 manufactured by Rigaku Corporation.
Output: Rh 50kV-72mA
Filter: OUT
Attenuator: 1/1
Slit: S4
Spectroscopic crystal: LiF (200)
Detector: PC
Peak angle (2θ/deg.): 126.790
Peak measurement time (sec): 40B.G.1.
(2θ/deg.): 124.25B. G. 2.
(2θ/deg.): 129.55B. G. 1.
Measurement time (seconds): 10B. G. 2.
Measurement time (sec): 10 PHA: 100-300
The concentration of tin oxide can also be measured using an electron probe microanalyzer (EPMA) and a wavelength dispersive X-ray detector (WDX) attached thereto. Specifically, based on the measurement results of WDX analysis using an EPMA (JXA8600, manufactured by JEOL Ltd.), divalent and tetravalent Sn is converted to tetravalent Sn.

As described later, the _SnO2 concentration distribution in the glass sheet can be adjusted in the production of the glass sheet by, for example, the rising speed, the hydrogen concentration in the air, the temperature of the molten metal bath and the dealkalization treatment, and the glass composition (for example, the _SnO2 content) during forming by the float method.

As an embodiment, FIG. 1 shows one aspect of the relationship when the horizontal axis is the depth from the first main surface and the vertical axis is the SnO ₂ concentration. In FIG. 1, t represents the sheet thickness, and t/2 represents the sheet thickness center. As shown in FIG. 1, in the glass sheet of this embodiment, in the region from the first main surface to a depth x1, the SnO ₂ concentration gradually increases to the SnO _{2 concentration at the sheet thickness center as the depth from the first main surface increases. Also, in the region from the depth x2 to the second main surface, the SnO 2 concentration} gradually increases from the concentration at the sheet thickness center as the depth from the first main surface increases.

In one embodiment of the glass plate, the depth from the first main surface to x1 (represented by a1 in FIG. 1) is preferably 1/10 or more and less than 1/2 of the plate thickness t, more preferably 1/9 or more and 1/3 or less, even more preferably 1/8 or more and 1/4 or less, and particularly preferably 1/7 or more and 1/5 or less, from the viewpoint of further improving the light extraction efficiency.

In one embodiment of the glass plate, the depth from x2 to the second main surface (represented by a2 in FIG. 1) is preferably 1/10 or more and less than 1/2 of the plate thickness t, more preferably 1/9 or more and 1/3 or less, even more preferably 1/8 or more and 1/4 or less, and particularly preferably 1/7 or more and 1/5 or less, from the viewpoint of further improving the light extraction efficiency.

In the glass plate according to one embodiment, when the horizontal axis represents the depth (mm) from the first main surface and the vertical axis represents the _SnO2 concentration (wt%), from the viewpoint of further improving the light extraction efficiency, the gradient (wt%/mm) at the depth from the first main surface to x1 is preferably 0.01 or more and 5.0 or less, more preferably 0.1 or more and 3.0 or less, even more preferably 0.2 or more and 2.0 or less, and particularly preferably 0.3 or more and 1.5 or less.

In the glass plate according to one embodiment, when the horizontal axis represents the depth (mm) from the first main surface and the vertical axis represents the _SnO2 concentration (wt%), from the viewpoint of further improving the light extraction efficiency, the gradient (wt%/mm) at the depth from x2 to the second main surface is preferably 0.01 or more and 5.0 or less, more preferably 0.1 or more and 3.0 or less, even more preferably 0.2 or more and 2.0 or less, and particularly preferably 0.3 or more and 1.5 or less.

2A and 2B each show an aspect of the relationship between the depth from the first main surface of the glass plate according to one embodiment and the _SnO2 concentration.
As shown in FIG. 2( a ), in the glass plate according to one embodiment, if (ΔSnO ₂ ) _T ≦(ΔSnO ₂ ) _B , warping of the glass is reduced, which is preferable.
As shown in FIG. 2B, the glass plate according to one embodiment is preferably such that (ΔSnO ₂ ) _T ≧(ΔSnO ₂ ) _B , since a larger refractive index difference can be created and the extraction efficiency is improved.

(composition)
The composition of the glass sheet according to this embodiment will be described below. The composition of the glass sheet will be described as the matrix composition. The matrix composition is equivalent to the composition at the center of the sheet thickness. In this specification, the glass composition is expressed in mass percentage based on oxides, and the term "%" indicates mass%.

The glass plate according to this embodiment may contain 0.10% to 2.5% SnO _2. Sn can be divalent or tetravalent, but in this specification, the concentration is expressed based on SnO _2. By having a SnO ₂ content of 0.10% or more, the glass surface layer on the first main surface and the second main surface can have a refractive index, thereby improving the light extraction efficiency. If the SnO ₂ content is too high, devitrification and coloring are likely to occur, so from the viewpoint of suppressing devitrification and coloring, the SnO ₂ content is 2.5% or less.

From the viewpoint of further improving the light extraction efficiency, the content of _SnO2 is preferably 0.15% or more, and more preferably 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, and 0.45% or more in the following stepwise manner. From the viewpoint of further suppressing devitrification and coloration, the content of _SnO2 is preferably 2.5% or less, more preferably 2.2% or less, particularly preferably 2.0% or less, and most preferably 1.8% or less.

The glass plate according to this embodiment preferably contains 55 to 75% SiO ₂ , 7.0 to 30% Al ₂ O ₃ , and 4.5 to 13.0% Li ₂ O.

More specifically, a more preferred composition of the glass plate according to this embodiment may include a composition _containing 55 to 75% _SiO2 , 7.0 to 30% _Al2O3 , 0.01 to 13.0% _Li2O , 0 to 18% _Na2O , 0.1 to 6.0% _ZrO2 , 1.0 to 9.0 _{% Y2O3} , _and 0 to 5.0% _P2O5 .

SiO ₂ is a component that forms a network structure of glass. It is also a component that increases chemical durability and can be a constituent of precipitated crystals. The content of SiO ₂ is preferably 55% or more, and is preferably 56% or more, 57% or more, 58% or more, 59% or more, 60% or more, 61% or more, and 62% or more in the following stepwise manner. The content of SiO ₂ may be 64% or more, 66% or more, or 67% or more. On the other hand, in order to improve the melting property, the content of SiO ₂ is preferably 75% or less, and is preferably 73% or less, 72% or less, 71% or less, 70% or less, 69% or less, 68% or less, 67% or less, 66% or less, 65% or less, 64% or less, 63% or less, 62% or less, 61% or less, and 60% or less in the following stepwise manner.

Al ₂ O ₃ is a component that increases the surface compressive stress due to chemical strengthening. The content of Al ₂ O ₃ is preferably 7.0% or more, and is preferably 8.0% or more, 8.5% or more, 9.0% or more, 9.5% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0% or more, 14.0% or more, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, 19.0% or more, 20.0% or more, 21.0% or more, 22.0% or more, 23.0% or more, 24.0% or more, and 25.0% or more. On the other hand, from the viewpoint of suppressing an excessively high devitrification temperature of the glass, the content of Al ₂ O ₃ is preferably 30% or less, and is stepwise increased to 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, and 18% or less.

Li ₂ O is a component that forms surface compressive stress by ion exchange, and can also be a component of precipitated crystals. The content of _{Li 2} O is preferably 0.01% or more, and is preferably 0.05% or more, 0.1% or more, 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, and 4.0% or more in the following stepwise manner. The content of Li ₂ O may be 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, or 6.5% or more. On the other hand, in order to stabilize the glass, the content of Li ₂ O is preferably 13.0% or less, and thereafter, stepwise, preferably, 12.0% or less, 11.0% or less, 10.5% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, and 5.0% or less.

Na ₂ O is a component that improves the melting property of glass. When Na ₂ O is contained, the content is preferably 0.2% or more, and is preferably 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, and 1.0% or more in the following stepwise manner. If Na ₂ O is too much, crystals are difficult to precipitate or the chemical strengthening properties are reduced, so it is preferably 18% or less, and is preferably 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, and 1.0% or less in the following stepwise manner.

K ₂ O is a component that lowers the melting temperature of glass like Na ₂ O, and may be contained. When K ₂ O is contained, the content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.3% or more, particularly preferably 0.4% or more, and most preferably 0.5% or more. If K ₂ O is too much, the chemical strengthening properties are reduced or the chemical durability is reduced, so 8.0% or less is preferable, and the following stepwise are preferable: 5.0% or less, 3.0% or less, 2.0% or less, 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, and 1.0% or less.

In the glass plate according to this embodiment, the total content Na ₂ O and K ₂ O (Na ₂ O + K ₂ O) is preferably 0% or more and 3.0% or less. From the viewpoint of improving the melting property of the glass, Na ₂ O + K ₂ O is more preferably 0.2% or more, even more preferably 0.4% or more, even more preferably 0.6% or more, particularly preferably 0.7% or more, and most preferably 0.8% or more. In addition, if Na ₂ O + K ₂ O is too high, the chemical strengthening properties are reduced or the chemical durability is reduced, so it is more preferably 2.7% or less, even more preferably 2.5% or less, even more preferably 2.3% or less, particularly preferably 2.2% or less, and most preferably 2.1% or less.

In the glass plate according to this embodiment, the total content of Li ₂ O, Na ₂ O and K ₂ O (Li ₂ O + Na ₂ O + K ₂ O) is R ₂ O, and R ₂ O is preferably 4.5% or more and 16% or less. From the viewpoint of improving the meltability of glass, R ₂ O is more preferably 5.0% or more, further preferably 6.0% or more, particularly preferably 6.5% or more, and most preferably 7.0% or more. In addition, from the viewpoint of improving chemical strengthening characteristics and chemical durability, R ₂ O is preferably 15% or less, and is preferably 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, and 7% or less in a stepwise manner.

In the glass plate according to this embodiment, from the viewpoint of enhancing chemical strengthening properties and chemical durability, K ₂ O/R ₂ O is preferably 0.20 or less, more preferably 0.15 or less, even more preferably 0.13 or less, particularly preferably 0.12 or less, and most preferably 0.11 or less. The lower limit of _{K 2} O/R ₂ O is not particularly limited, but may be, for example, 0.003 or more, 0.01 or more, 0.03 or more, 0.05 or more, or 0.10 or more.

_ZrO2 is a component that can form a crystal nucleus during crystallization treatment, and may be contained. The content of _ZrO2 is preferably 0.1% or more, and is preferably 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, and 2.5% or more in a stepwise manner. The content of _ZrO2 may be 3.0% or more. On the other hand, in order to suppress devitrification during melting, the content of _ZrO2 is preferably 6.0% or less, and is preferably 5.5% or less, 5.0% or less, 4.5% or less, 4.2% or less, 4.0% or less, 3.5% or less, and 3.0% or less in a stepwise manner.

In addition, when the total content of _Li2O , _Na2O and _K2O ( _Li2O + _Na2O + _K2O ) is _R2O , _ZrO2 / _R2O is preferably 0.1 or more, more preferably 0.2 or more, from the viewpoint of improving chemical durability. From the viewpoint of improving transparency after crystallization, _ZrO2 / _R2O is preferably 0.8 or less, more preferably 0.6 or less.

Y ₂ O ₃ is a component that makes it difficult for fragments to scatter when the chemically strengthened glass is broken, and may be contained. The content of _{Y 2} O ₃ is preferably 1.0% or more, more preferably 1.3% or more, even more preferably 1.6% or more, particularly preferably 1.9% or more, and most preferably 2.1% or more. On the other hand, in order to suppress devitrification during melting, the content of Y ₂ O ₃ is preferably 9.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, particularly preferably 6.0% or less, and most preferably 5.0% or less.

P ₂ O ₅ is not essential, but may be contained since it has the effect of promoting the phase separation of glass and promoting crystallization. When _{P 2} O ₅ is contained, the content is preferably 0.2% or more, and is preferably 0.4% or more, 0.6% or more, 0.8% or more, 1.0% or more, 1.5% or more, 2.0% or more, and 2.5% or more in a stepwise manner. On the other hand, if the content of P ₂ O ₅ is too high, phase separation occurs easily during melting, and acid resistance is significantly reduced. The content of P ₂ O ₅ is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 4.0% or less, particularly preferably 3.7% or less, and most preferably 3.5% or less.

TiO ₂ is a component that can form a crystal nucleus during crystallization treatment, and may be contained. TiO ₂ is not essential, but if it is contained, it is preferably 0.01% or more, and is preferably 0.05% or more, 0.08% or more, 0.10% or more, 0.15% or more, and 0.20% or more in the following stepwise manner. The content of TiO ₂ may be 1.0% or more, or may be 1.5% or more. On the other hand, in order to suppress devitrification during melting and to give color to the glass, the content of TiO ₂ is preferably 3.0% or less, and is preferably 0.8% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, and 0.15% or less in the following stepwise manner.

Although B ₂ O ₃ is not essential, it is a component that improves the chipping resistance of the chemically strengthened glass or chemically strengthened glass and improves the meltability, and may be contained. When _{B 2} O ₃ is contained, the content is preferably 0% or more and 3.0% or less. From the viewpoint of further improving the meltability, the content of _{B 2} O ₃ is more preferably 0.2% or more, even more preferably 0.4% or more, particularly preferably 0.6% or more, and most preferably 0.8% or more. On the other hand, in order to suppress the occurrence of striae during melting and to prevent the quality of the chemically strengthened glass from being easily separated, the content of B ₂ O ₃ is more preferably 2.0% or less, even more preferably 1.5% or less, particularly preferably 1.0% or less, and most preferably 0.8% or less.

BaO, SrO, MgO, CaO and ZnO are components that improve the meltability of glass and may be contained. When these components are contained, the total content of BaO, SrO, MgO, CaO and ZnO, BaO+SrO+MgO+CaO+ZnO, is preferably more than 0% and 3.0% or less. From the viewpoint of further improving the meltability of glass, BaO+SrO+MgO+CaO+ZnO is more preferably 0.1% or more, even more preferably 0.2% or more, particularly preferably 0.3% or more, and most preferably 0.5% or more. On the other hand, from the viewpoint of suppressing a decrease in the ion exchange rate, BaO+SrO+MgO+CaO+ZnO is preferably 2.5% or less, and thereafter, in steps, 2.0% or less, 1.8% or less, 1.5% or less, 1.0% or less, 0.8% or less, 0.6% or less, 0.4% or less, and 0.2% or less are preferable.

Among the above components, BaO, SrO and ZnO may be contained to improve the refractive index of the residual glass and bring it closer to the precipitated crystal phase, thereby improving the light transmittance of the crystallized glass and reducing the haze value. In this case, the total content of BaO+SrO+ZnO is preferably 0% or more and 1.0% or less. BaO+SrO+ZnO is more preferably 0.05% or more, even more preferably 0.10% or more, particularly preferably 0.20% or more, and most preferably 0.30% or more. On the other hand, these components may reduce the ion exchange rate. From the viewpoint of improving the chemical strengthening characteristics, BaO+SrO+ZnO is more preferably 0.8% or less, even more preferably 0.6% or less, and particularly preferably 0.5% or less. BaO+SrO+ZnO may also be 0.4% or less.

_CeO2 has the effect of oxidizing glass and may suppress coloring, so it may be contained. When _CeO2 is contained, the content is preferably 0% or more and 1.0% or less. The content of _CeO2 is more preferably 0.1% or more, even more preferably 0.2% or more, particularly preferably 0.3% or more, and most preferably 0.4% or more. When _CeO2 is used as an oxidizing agent, the content of _CeO2 is more preferably 0.8% or less, even more preferably 0.7% or less, particularly preferably 0.6% or less, and most preferably 0.5% or less in order to increase transparency.

When the glass is colored and used, coloring components may be added within a range that does not inhibit the achievement of _the desired chemical strengthening characteristics. Suitable examples of coloring components include CoO, _Co3O4 , MnO, _MnO2 , FeO, _Fe2O3 , NiO, _CuO , _Cu2O , _Cr2O3 , _V2O5 , _Bi2O3 , _SeO2 , _Se , _Er2O3 , _Nd2O3 , _Eu2O3 , and _{Pr6O11 .} The total content of _the coloring components is preferably _1.0 % or less. More preferably, _it is 0.8% or less, even more preferably 0.6 _% or less, and most preferably 0.4% or less. If it is desired to increase _the visible light transmittance of the glass, it is preferable that these components are not substantially contained.

As a fining agent for melting the glass, SO ₃ , chlorides, fluorides, etc. may be appropriately contained. It is preferable that _{As 2} O ₃ is not contained. When _{As 2} O ₃ is contained, it is preferably 0.3% or less, more preferably 0.1% or less, and most preferably not contained.

The glass composition is not particularly limited, but specific examples include the following glass compositions.
(1) Glass containing, in mass % on an oxide basis, 60-66% _SiO2 , _18.0-23 % _Al2O3 , 4.5-9.0% _Li2O , and 1.50-2.5% _SnO2 . (2) Glass containing, in mass % on an oxide basis, 60-66% _SiO2 , 7.0-18% _Al2O3 , 7-11.0% _Li2O , and _1.00-2.5 % _SnO2 . (3) Glass containing, in mass % on an oxide basis, 65-75% _SiO2 , 8.0-13% _Al2O3 , 7-11.0% Li2O, and 1.50-2.5% _SnO2 . (4) Glass containing, in mass % on an oxide basis, 65-75% _SiO2 , 8.0-13% _Al2O3 , 7-11.0% _Li2O , and 1.50-2.5% _SnO2 . (5) Glass containing, in mass % on an oxide basis, 60-66% _SiO2 , 12.0-18% _Al2O3 , 4.5-9.0% _Li2O , and 0.50-1.5% _{SnO2 .} (6) Glass containing, in mass % on an oxide basis, 60-66% _SiO2 , _23-27 % _Al2O3 , _3.5-5.0 % _Li2O , 1.0-2.0% _Na2O , 0.1-0.5% _K2O , _0.01-0.2 % _TiO2 , _2.5-3.5 % _ZrO2 , and SnO (7) Glass containing, in mass % on an oxide basis, 60-66% _SiO2 , 18-24% _Al2O3 , 4.0-6.0% _Li2O , 0.5-1.5% _Na2O , 0.1-1.5% _K2O , 0.01-0.2% _TiO2 , 2.0-3.5% _ZrO2 , and 1.5-3.0% _SnO2 . (8) Glass containing, in mass % on _an oxide basis, 56-60% _SiO2 , _25-29 % _Al2O3 , 4.5-7.0% _Li2O , 0.3-1.0% _Na2O , 0.1-0.5% _K2O , and 1.5-3.0% _TiO2 . Glass containing 0.01-0.2% _SiO2 , 2.5-3.5% _ZrO2 , and 1.5-3.0% _SnO2 (9) Glass containing, in mass % on an oxide basis, 60-64% _SiO2 , 20-24% _Al2O3 , 3.5-5.5% _Li2O , 0.8-1.5% _Na2O , 0.5-1.0% _K2O , 0.01-0.2% _TiO2 , 2.5-3.5% _ZrO2 , _and 1.5-3.0% SnO2 (10) Glass containing, in mass % on an oxide basis, 58-62% _SiO2 , _{21-25 % Al2O3} , 3.5-5.5% _Li2O , and 1.5-3.0% _Na2O Glass containing 0.5-1.5% O, 0.3-1.5% K ₂ O, 0.01-0.2% TiO ₂ , and 2.0-3.0% ZrO ₂ (11) Glass containing, in mass % on an oxide basis, 58-62% SiO ₂ , 21-25% Al ₂ O ₃ , 3.5-5.5% Li ₂ O, 0.5-1.5% Na ₂ O, 0.3-1.5% K ₂ O, 0.01-0.2% TiO _{2, 2.0-3.5% ZrO 2} , and 1.5-3.0% SnO _{2 .}

(visible light transmittance)
The glass plate according to this embodiment has a visible light transmittance of preferably 91.0% or more when converted to a thickness of 0.7 mm, so that when used as a protective member for a display device, the display screen is easily visible. The visible light transmittance is more preferably 91.2% or more, and even more preferably 91.4% or more. The higher the visible light transmittance, the more preferable it is, but it is usually 92% or less. The visible light transmittance of ordinary amorphous glass is about 90%. The visible light transmittance can be measured by a method in accordance with JIS R3106 (2019).

(Haze value)
The glass plate according to this embodiment has a haze value of preferably 0.50% or less, more preferably 0.30% or less, even more preferably 0.20% or less, particularly preferably 0.10% or less, and most preferably 0.05% or less, when measured at a thickness of 0.7 mm. The smaller the haze value, the more preferable it is. The haze value is a value measured according to JIS K7136 (2000).

In addition, when the total light visible light transmittance of a crystallized glass having a plate thickness t [mm] is T [%] and the surface reflectance of one side is R [%], the Lambert-Beer law
By using the law of t=1−R/100, the relationship T/100=(1−R/100) ² ×exp(−αt) is established using a constant α.
If α is expressed as R, T, and t, and t = 0.7 mm, then R does not change with the plate thickness, so the total light visible light transmittance _T0.7 /100 converted to 0.7 mm can be calculated as _T0.7 /100 = T/1000.7 ^/t/(1-R /100)^(1.4/t-2), where X^Y represents ^XY .

(Thickness)
The thickness of the glass plate according to this embodiment is 0.30 to 1.00 mm. The thickness is preferably 0.90 mm or less, more preferably 0.80 mm or less, even more preferably 0.70 mm or less, particularly preferably 0.65 mm or less, and most preferably 0.60 mm or less. From the viewpoint of further increasing the strength, the thickness is preferably 0.35 mm or more, more preferably 0.40 mm or more, even more preferably 0.45 mm or more, and particularly preferably 0.50 mm or more.

The shape of the glass plate according to this embodiment may be a shape other than a plate shape, depending on the product to which it is applied, its use, etc. The glass plate may also have a border shape with a different thickness around the periphery. The shape of the glass plate is not limited to this, and for example, the two main surfaces do not have to be parallel to each other, and one or both of the two main surfaces may be entirely or partially curved. More specifically, the glass plate may be, for example, a flat glass plate without warping, or a curved glass plate having a curved surface.

<<Ceramics>>
The glass plate according to the present embodiment is preferably crystallized glass. The crystallized glass is obtained by heating and crystallizing amorphous glass. The glass composition of the crystallized glass is the same as the composition of the amorphous glass before crystallization. That is, the matrix composition of the crystallized glass according to the present embodiment is the same as the composition of the glass plate according to the present embodiment described above, and the preferred composition range is also the same.

In this specification, the term "crystallized glass" refers to glass in which a diffraction peak indicating crystallization is observed by X-ray diffraction (XRD). X-ray diffraction measurement can be performed, for example, by using CuKα radiation to measure the range of 2θ from 10° to 80°. Examples of the crystals include, for example, β-spodumene crystals, lithium disilicate crystals, β-quartz crystals, lithium metasilicate crystals, and lithium phosphate crystals, which are crystals containing lithium. These crystals may form solid solutions and dissolve various elements. In particular, the elements that dissolve are alkali metals (Na, K) and alkaline earth metals (Mg, Ca, Sr, Ba), but this is not necessarily the case. In addition, examples of crystals that do not contain lithium include ZrO ₂ and solid solutions thereof. Examples of the elements that dissolve are Y, Sn, etc., but this is not necessarily the case.
The crystallized glass preferably contains β-spodumene as crystals. Since β-spodumene has a denser crystal structure than β-quartz solid solution, it is considered that when ions in the precipitated crystals are replaced with larger ions by ion exchange treatment for chemical strengthening, high compressive stress is generated, and the effect of chemical strengthening is enhanced. In addition, the crystallized glass may contain virgilite. Virgilite is also called keatite, and is a crystal expressed as LiAlSi ₂ O ₆ like β-spodumene, but has a different crystal structure.

The crystallization rate of the crystallized glass is preferably 60% or more to increase the mechanical strength, more preferably 65% or more, even more preferably 70% or more, and particularly preferably 75% or more. Also, to increase transparency, it is preferably 90% or less, more preferably 85% or less, and particularly preferably 80% or less. A small crystallization rate is also advantageous in that it is easier to heat and bend the glass.

The crystallinity rate can be calculated from the X-ray diffraction intensity using the Rietveld method. The Rietveld method is described in the "Crystal Analysis Handbook" (Kyoritsu Shuppan, 1999, pp. 492-499), edited by the Editorial Committee for the "Crystal Analysis Handbook" of the Crystallographic Society of Japan.

To increase transparency, the average particle size of the precipitated crystals in the crystallized glass is preferably 150 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, and particularly preferably 20 nm or less. The average particle size of the precipitated crystals can be determined from a transmission electron microscope (TEM) image. It can also be estimated from a scanning electron microscope (SEM) image.

<<Chemically strengthened glass>>
The glass plate according to the present embodiment is preferably a chemically strengthened glass. The chemically strengthened glass according to the present embodiment is obtained by chemically strengthening the glass plate according to the present embodiment described above. That is, the base composition of the chemically strengthened glass according to the present embodiment is the same as the composition of the glass plate according to the present embodiment described above, and the preferred composition range is also the same.

When chemically strengthened glass is in plate form, the content of alkali metal elements differs between the surface and the center in the thickness direction. On the other hand, except in cases where extreme ion exchange treatment has been performed, the glass composition in the deepest part from the surface of the chemically strengthened glass is the same as the base composition of the chemically strengthened glass. When chemically strengthened glass is in plate form, the deepest part from the glass surface is, for example, a depth of 1/2 the plate thickness t.

(Stress characteristics)
In this specification, "compressive stress layer depth (DOL)" is the depth at which the compressive stress value CS becomes zero. The surface compressive stress value CS ₀ and the compressive stress layer depth DOL can be measured using a surface stress meter [for example, a surface stress meter (FSM-6000) manufactured by Orihara Seisakusho]. The preferred plate thickness (t) and preferred shape of the chemically strengthened glass according to this embodiment are the same as the preferred plate thickness (t) and shape of the glass plate according to this embodiment described above.

The chemically strengthened glass according to this embodiment preferably has a surface compressive stress value CS ₀ of 300 MPa or more, more preferably 350 MPa or more, even more preferably 400 MPa or more, and even more preferably 450 MPa or more. The upper limit of the surface compressive stress value CS ₀ is not particularly limited, but the surface compressive stress value CS ₀ may be, for example, 1400 MPa or less.

If the compressive stress layer depth DOL of the chemically strengthened glass according to this embodiment is too large relative to the thickness t (mm), the CT may become too large, so it is preferably 0.30t or less, and more preferably 0.20t or less. From the viewpoint of improving strength, the DOL is preferably 0.10t or more, and more preferably 0.15t or more.

(reflectance)
The chemically strengthened glass according to this embodiment preferably has a reflectance of 4.4% or less on the first main surface. By having a reflectance of 4.4% or less on the first main surface, the extraction efficiency of light emitted from the center of the thickness of the glass to the outside through the first main surface can be improved. The reflectance on the first main surface is more preferably 4.3% or less, even more preferably 4.2% or less, and particularly preferably 4.1% or less.

The chemically strengthened glass according to this embodiment preferably has a reflectance of 4.4% or more at the second principal surface. With a reflectance of 4.4% or more at the second principal surface, the efficiency of capturing light entering from the second principal surface toward the center of the plate thickness can be increased, resulting in a further improvement in the efficiency of extracting light from the first principal surface. The reflectance at the second principal surface is more preferably 4.45% or more, even more preferably 4.50% or more, and particularly preferably 4.55% or more.

Reflectance can be measured using a UV-Visible spectrophotometer by installing a reflectance unit (e.g., a Perkin Elma Lambda 900 and an automatic angle variable universal reflectance accessory). In order to measure only one side, it is necessary to eliminate reflection from the surface opposite the measurement surface. This can be done, for example, by roughening the surface with a file or by installing a prism to allow light to escape.

<Application>

The glass plate according to this embodiment can be used as cover glass for mobile electronic devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet terminals. It is also useful as cover glass for electronic devices that are not intended to be portable, such as televisions (TVs), personal computers (PCs), and touch panels. It is also useful as building materials such as window glass, table tops, and the interiors of automobiles and airplanes, as well as cover glass for these (for example, vehicle-mounted cover glass).

The glass plate according to this embodiment can be bent or shaped before or after chemical strengthening to form it into a shape other than a flat plate, making it useful for applications such as enclosures with curved surfaces.

<<Method of manufacturing glass sheet>>
The method for producing a glass plate according to the present embodiment preferably includes at least the following step (1), more preferably includes at least one of the following steps (2) and (3) in addition to the step (1), and further preferably includes the following steps (1) to (3): (1) Step of producing amorphous glass (2) Step of heat-treating glass to obtain crystallized glass (3) Step of ion-exchange-treating glass to obtain chemically strengthened glass Each step will be described below.

(1) Step of Producing Amorphous Glass Amorphous glass can be produced, for example, by the following method. Glass raw materials are mixed so as to obtain glass of a desired composition, and heated and melted in a glass melting furnace. The molten glass is then homogenized by bubbling, stirring, adding a fining agent, etc., and formed into a glass plate of a predetermined thickness by a known forming method, and slowly cooled.

The preferred forming method is the float method. The float method refers to a method in which molten glass is poured onto a molten metal bath and formed into a sheet. In this specification, the upstream side of the molten metal bath refers to the side where the molten glass flows in, and the downstream side refers to the side where the glass formed into a ribbon shape is discharged.

Figure 3 shows a schematic diagram of a glass manufacturing apparatus using the float method. As shown in Figure 3, the glass manufacturing apparatus using the float method has a melting furnace 10, a float bath 20, and an annealing furnace (lehr) 30. In manufacturing glass using the float method, glass raw materials are first melted in the melting furnace 10 to obtain molten glass. The melting furnace 10 has a melting kiln 11, in which the glass raw materials 1 charged are melted to obtain molten glass 2. More specifically, the melting kiln 11 has a melting tank 12 on the upstream side and a cooling tank 13 on the downstream side, which are connected by a neck 14 (or throat), and the glass raw materials 1 are melted on the upstream side (i.e., the melting tank) to become molten glass 2, and the temperature of the molten glass 2 is adjusted on the downstream side.

Next, molten glass 2 is continuously supplied from the upstream side onto the surface of the molten metal bath 21 stored in the float bath 20 to form a glass ribbon 3. The formed glass ribbon 3 is then drawn out from the downstream end of the float bath 20 and introduced into an annealing furnace (lehr) 30 for annealing, thereby producing sheet glass. The glass ribbon 3 introduced into the lehr 30 is annealed while being transported to an annealing furnace (not shown) by a transport means such as a roller conveyor. Since the molten glass 2 on the molten metal bath 21 and the glass ribbon 3 in the lehr 30 are continuous, the transport speed (lehr speed) in the lehr 30 depends on the speed at which the molten glass 2 flows from upstream to downstream on the molten metal bath 21. Although the glass ribbon 3 in the lehr 30 is solidified, the molten glass 2 flows, so the speed of the molten glass 2 is slower than the lehr speed, and the speed of the molten glass 2 on the molten metal bath 21 tends to be faster downstream. The type of molten metal is not particularly limited, but molten tin is an example.

As described above, in this embodiment, the _SnO2 concentration distribution in the glass sheet can be adjusted by 1) the lee speed, 2) the hydrogen concentration in the air, 3) the temperature of the molten metal bath, and 4) the glass composition (e.g., the _SnO2 content) during forming by the float method. Each item will be explained below.

1) Rare speed during float forming The rare speed is preferably 20 m/h or more, more preferably 100 m/h or more, even more preferably 200 m/h or more, particularly preferably 300 m/h or more, and most preferably 400 m/h or more. If the rare speed is too high, the quality of the glass is likely to deteriorate, so the rare speed is preferably 1200 m/h or less, more preferably 1000 m/h or less, even more preferably 900 m/h or less, particularly preferably 850 m/h or less, and most preferably 800 m/h or less.

2) Hydrogen Concentration in the Atmosphere During Float Forming The hydrogen concentration in the atmosphere during float forming can be adjusted by the concentration of gas such as reducing gas or oxidizing gas supplied to the glass during float forming, the amount of gas sprayed, the main surface to be sprayed, the treatment temperature and time, etc. Examples of the gas supply include supply from a hole in the ceiling disposed at an interval from the molten metal bath 21, and spraying the gas against the glass sheet in an annealing furnace.

The reducing gas may be, for example, nitrogen gas, hydrogen gas, carbon monoxide gas, or a mixture of these. The reducing gas may contain an inert gas such as air, nitrogen, or argon as a carrier gas. The reducing gas may be supplied, for example, from a hole in the ceiling spaced apart from the molten metal bath 21. Specific examples of the reducing gas treatment conditions include a mixed gas of 0.1 to 100 cc/min and a treatment temperature of 600 to 1200°C. The mixed gas is, for example, a mixed gas of nitrogen gas and hydrogen gas, containing 80% to 99.5% by volume of nitrogen gas and 0.5% to 20% by volume of hydrogen gas.

Examples of the oxidizing gas include sulfur dioxide gas ( _SO2 gas), hydrofluoric acid gas, oxygen gas, or a mixture thereof. The oxidizing gas may contain an inert gas such as air, nitrogen, or argon as a carrier gas. The oxidizing gas may further contain water vapor. The oxidizing gas is, for example, sprayed onto the main surface of the glass plate (preferably at least the top surface, specifically, for example, only the first main surface or both the first main surface and the second main surface) in an annealing furnace. Specific examples of the treatment conditions for the oxidizing gas include a mixed gas of 0.1 to 100 cc/min and a treatment temperature of 600 to 1200°C. The mixed gas may vary, for example, in an oxygen content range of 0.5% by volume to 10% by volume or higher. In some embodiments, the mixed gas may be oxygen gas with a maximum of 100% by volume.

3) Temperature of the molten metal bath during float forming The temperature of the molten metal bath is preferably 700° C. or higher, more preferably 800° C. or higher, even more preferably 850° C. or higher, and particularly preferably 900° C. or higher. From the viewpoint of volatilization of metallic tin, the temperature is preferably 1300° C. or lower, more preferably 1250° C. or lower, even more preferably 1200° C. or lower, and particularly preferably 1150° C. or lower.

4) Glass composition The _SnO2 concentration distribution in the glass sheet can also be adjusted by adjusting the _SnO2 concentration of the matrix composition. The preferred range of the _SnO2 concentration of the matrix composition is the same as the range described above in the section <Glass sheet> (composition).

(2) Step of Heating Glass to Obtain Crystallized Glass The amorphous glass obtained by the above procedure is heat-treated (thermal treatment) to obtain crystallized glass. In this case, the heat treatment includes a multi-stage heat treatment of two or more stages. The multi-stage heat treatment means a heat treatment in which a predetermined temperature range is held for a predetermined time, and the temperature range is changed and the like is held multiple times. Specifically, the multi-stage heat treatment can be, for example, a two-stage heat treatment in which the temperature is raised from room temperature to a first treatment temperature and held for a certain time, and then the second treatment temperature, which is higher than the first treatment temperature, is held for a certain time.

When using a two-stage heat treatment, the first treatment temperature is preferably in a temperature range where the crystal nucleation rate is high for that glass composition, and the second treatment temperature is preferably in a temperature range where the crystal growth rate is high for that glass composition. In addition, it is preferable to hold the first treatment temperature for a long time so that a sufficient number of crystal nuclei are generated. By generating a large number of crystal nuclei, the size of each crystal becomes small, and highly transparent crystallized glass is obtained.

When using a two-stage heat treatment, the first treatment temperature is, for example, 550°C to 800°C, and the second treatment temperature is, for example, 850°C to 1000°C, and after being held at the first treatment temperature for 2 to 10 hours, it is held at the second treatment temperature for 2 to 10 hours.

The heating and cooling rates in each stage of heat treatment are preferably 5 to 120°C/min. A heating and cooling rate of 5°C/min or more is preferable because it allows the rate to follow the rate of crystal formation within the material. On the other hand, a heating and cooling rate of 120°C/min or less is preferable because it allows the deformation of the material to be suppressed.

The molten glass is homogenized and formed into a glass plate of a specified thickness, or the molten glass is formed into a block shape, followed by a continuous crystallization process. The crystallized glass obtained by the above procedure is ground and polished as necessary to form a crystallized glass plate.

(3) Step of Obtaining Chemically Strengthened Glass by Ion Exchange Treatment of Glass In this embodiment, the chemical strengthening treatment (ion exchange treatment) is performed by, for example, immersing the glass plate for 0.1 to 500 hours in a molten salt such as potassium nitrate heated to 360 to 600° C. The heating temperature of the molten salt is preferably 375 to 500° C., and the immersion time of the glass plate in the molten salt is preferably 0.3 to 200 hours.

Examples of molten salts for carrying out chemical strengthening treatment include nitrates, sulfates, carbonates, and chlorides. Among these, examples of nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Examples of sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Examples of carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Examples of chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These molten salts may be used alone or in combination.

In this embodiment, the processing conditions for the chemical strengthening treatment can be appropriately selected taking into consideration the properties and composition of the glass for chemical strengthening, the type of molten salt, and the chemical strengthening properties, such as the surface compressive stress and the depth of the compressive stress layer, desired for the final chemically strengthened glass.

In particular, it is preferable to perform a long-term chemical strengthening treatment on amorphous glass or crystallized glass, which has a large fracture toughness value. When an ion exchange reaction progresses due to a long-term chemical strengthening treatment, a large compressive stress is generated in the surface layer, and at the same time, a decrease in compressive stress occurs mainly near the surface due to structural relaxation, making it easier to achieve the compressive stress balance of this embodiment.

In addition, in this embodiment, the chemical strengthening treatment may be performed only once, or multiple chemical strengthening treatments (multi-stage strengthening) may be performed under two or more different conditions.

<Laminate>
The laminate according to this embodiment is a laminate including the glass plate according to the embodiment described above and a liquid crystal glass plate, wherein a first main surface of the glass plate is the outermost surface of the laminate, a second main surface of the glass plate is a lamination surface with the liquid crystal glass plate, and the absolute value of the difference between the refractive index of the second main surface of the glass plate measured with a prism coupler and the refractive index of the liquid crystal glass plate measured with a prism coupler is 0.001 to 0.20.

In the laminate according to this embodiment, the absolute value of the difference between the refractive index measured with a prism coupler on the second main surface of the glass plate and the refractive index measured with a prism coupler on the liquid crystal glass plate is preferably 0.001 to 0.20, which allows light to easily enter the glass plate from the liquid crystal glass plate and suppresses light loss.

From the viewpoint of further suppressing the loss of light entering the glass plate from the liquid crystal glass plate, the laminate according to this embodiment preferably has an absolute value of the difference between the refractive index measured with a prism coupler of the second main surface of the glass plate and the refractive index measured with a prism coupler of the liquid crystal glass plate of 0.10 or less, more preferably 0.050 or less, even more preferably 0.030 or less, and particularly preferably 0.010 or less.

In the laminate according to this embodiment, the second main surface of the glass plate is the lamination surface with the liquid crystal glass plate, but an intermediate layer may be included between the glass plate and the liquid crystal glass plate. Examples of intermediate layers include an adhesive layer, a printed layer, and a functional layer (e.g., an optical filter layer, a refractive index matching layer). In the laminate according to this embodiment, a functional layer (e.g., an anti-fouling layer, an anti-reflection layer) may be laminated on the first main surface of the glass plate.

<Display device>
The display device according to the present embodiment includes the glass plate according to the present embodiment or the laminate according to the present embodiment. Examples of the display device according to the present embodiment include a display device such as an in-vehicle car navigation system and a portable display device such as a smartphone.

The present invention will be described in more detail below using examples, but the present invention is not limited to these. Examples 1 to 20 are examples, and Examples 21 to 31 are comparative examples.

<Examples 1 to 20: Production of Glass>
Glasses were prepared by the float process so as to have the compositions shown in Tables 1 to 3 in terms of mass percentage based on oxides.
In Examples 4, 6 to 8, 10, 12, and 14, a two-stage heat treatment was carried out under the conditions shown in the table to obtain glass plates of crystallized glass.

<Examples 21 to 31: Production of Glass>
Glass raw materials were mixed to obtain the compositions shown in Tables 3 and 4 in terms of mass percentage based on oxides, and weighed out to give 400 g of glass. The mixed raw materials were then placed in a platinum crucible and placed in an electric furnace at 1500 to 1700°C, melted for about 3 hours, degassed, and homogenized.
The molten glass thus obtained was poured into a metal mold and held at a temperature about 50° C. higher than the glass transition point for 1 hour, and then cooled to room temperature at a rate of 0.5° C./min to obtain a glass block. The obtained glass block was cut and ground, and finally both sides were polished to obtain a glass plate having a thickness of 0.7 mm.
For Examples 25, 27, and 28, a two-stage heat treatment was carried out under the conditions shown in Table 4 to obtain glass plates of crystallized glass.

<Glass evaluation>
Each of the glass plates obtained above was evaluated as follows.
For each glass, the tin oxide concentration (SnO ₂ ) _T near the surface layer on the top surface (first main surface) and the tin oxide concentration (SnO ₂ ) _B near the surface layer on the bottom surface (second main surface) were evaluated.
The concentration of tin oxide was measured for the same glass plate as that used in the examples and comparative examples using an electron probe microphone analyzer (EPMA) and a wavelength dispersive X-ray detector (WDX) attached thereto. Specifically, WDX analysis was performed using an EPMA (JXA8600, manufactured by JEOL Ltd.). From the measurement results, divalent and tetravalent Sn was converted to tetravalent. Then, the tin oxide concentration in terms of SnO ₂ at a depth of 10 μm from the top surface was averaged, and this was taken as the SnO ₂ concentration (SnO ₂ ) _T at the top surface (first main surface). In addition, the tin oxide concentration in terms of SnO 2 at a depth of ₁₀ μm from the bottom surface was averaged, and this was taken as the SnO ₂ concentration (SnO ₂ ) _B at the bottom surface (second main surface). The tin oxide concentration in terms of _SnO2 at the center of the sheet thickness was also measured in the same manner, and Δ( _SnO2 ) _T and Δ( _SnO2 ) _B were calculated from these values.

Next, the refractive index of each glass was measured on the top surface (first main surface) and the bottom surface (second main surface) using a prism coupler (633 nm). The results are shown in Tables 1 to 4. The "-" in the "crystallization conditions" column indicates that no crystallization treatment was performed.

As a result, in the working examples, Examples 1 to 20, the refractive index of the bottom surface (second main surface) was greater than that of the top surface (first main surface). From this, when used as cover glass for a display, it is expected that light will easily enter the second main surface from the liquid crystal glass plate because the refractive index of the bottom surface can be made closer to the refractive index of the glass on the surface of the light-emitting component. In addition, since the glass surface layer on the top surface has a refractive index distribution, it is expected that light will easily be emitted from the center of the glass thickness through the first main surface to the outside. In other words, when used as cover glass with the bottom surface of the glass plate facing the display, it is expected that the light extraction efficiency can be further improved.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent application (Patent Application No. 2023-206284) filed on December 6, 2023, Japanese patent application (Patent Application No. 2024-163789) filed on September 20, 2024, Japanese patent application (Patent Application No. 2024-114047) filed on July 17, 2024, and Japanese patent application (Patent Application No. 2024-114101) filed on July 17, 2024, and is incorporated by reference in its entirety. In addition, all references cited herein are incorporated by reference in their entirety. In addition, all references cited herein are incorporated by reference in their entirety.

1 Glass raw material; 2 Molten glass; 3 Glass ribbon; 10 Melting furnace; 11 Melting furnace; 12 Melting tank; 13 Cooling tank; 14 Neck; 20 Float bath; 21 Molten metal bath; 22 Top roll; 23 Restrictor; 30 Lehr (lehr)

Claims (17)

A first main surface and a second main surface opposite to the first main surface,
The thickness is 0.30 to 1.00 mm,
A glass plate satisfying the following formulas (1) and (2) in terms of mass percentage based on oxides.
0.03≦(ΔSnO ₂ ) _T ≦1.0 (1)
0.20≦(ΔSnO ₂ ) _B ≦1.5 (2)
(ΔSnO ₂ ) _T : Value (%) obtained by subtracting [SnO ₂ concentration (%) on the first main surface] from [SnO ₂ concentration (%) on the sheet thickness center]
(ΔSnO ₂ ) _B : Value (%) obtained by subtracting [SnO ₂ concentration (%) at the center of sheet thickness] from [SnO ₂ concentration (%) at the second main surface] 2. The glass plate according to claim 1, wherein the value obtained by subtracting the SnO ₂ concentration (%) at the first main surface from the SnO ₂ concentration (%) at a depth of 100 μm from the first main surface is 0 to 0.9%, expressed in mass percentage based on oxide. 2. The glass plate according to claim 1, wherein the SnO ₂ concentration (%) at a depth of 100 μm from the _second main surface is 0.15 to 1.4%, expressed in mass percentage based on oxides. The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 55-75%,
7.0 to 30% Al ₂ O ₃ ,
2. The glass plate according to claim 1, containing 0.01 to 13.0% of Li ₂ O. The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 55-75%,
7.0 to 30% Al ₂ O ₃ ,
0.01 to 13.0% Li ₂ O,
0-18% Na ₂ O,
_ZrO2 from 0.1 to 6.0%,
1.0 to 9.0% Y ₂ O ₃ ,
The glass plate according to claim 4, containing 0 to 5.0% of P ₂ O ₅ . The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 60-66%,
23-27% Al ₂ O ₃ ,
3.5 to 5.0% Li ₂ O,
1.0-2.0% Na ₂ O,
K ₂ O 0.1 to 0.5%,
_TiO2 0.01-0.2%,
_ZrO2 2.5-3.5%,
The glass plate according to claim 4, containing 0.4 to 1.0% _SnO2 . The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 60-66%,
18-24% Al ₂ O ₃ ,
4.0 to 6.0% Li ₂ O,
0.5-1.5% Na ₂ O,
K ₂ O 0.1 to 1.5%,
_TiO2 0.01-0.2%,
_ZrO2 from 2.0 to 3.5%,
The glass plate according to claim 4, containing 1.5 to 3.0% _SnO2 . The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 56-60%,
25-29% Al ₂ O ₃ ,
4.5 to 7.0% Li ₂ O,
0.3-1.0% Na ₂ O,
K ₂ O 0.1 to 0.5%,
_TiO2 0.01-0.2%,
_ZrO2 2.5-3.5%,
The glass plate according to claim 4, containing 1.5 to 3.0% _SnO2 . The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 60 to 64%,
20-24% Al ₂ O ₃ ,
3.5-5.5% Li ₂ O,
0.8-1.5% Na ₂ O,
K ₂ O 0.5 to 1.0%,
_TiO2 0.01-0.2%,
_ZrO2 2.5-3.5%,
The glass plate according to claim 4, containing 1.5 to 3.0% _SnO2 . The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 58-62%,
21-25% Al ₂ O ₃ ,
3.5-5.5% Li ₂ O,
0.5-1.5% Na ₂ O,
K ₂ O 0.3 to 1.5%,
_TiO2 0.01-0.2%,
The glass plate according to claim 4, containing 2.0 to 3.0% _ZrO2 . The matrix composition is expressed as a mass percentage based on oxides.
_SiO2 58-62%,
21-25% Al ₂ O ₃ ,
3.5-5.5% Li ₂ O,
0.5-1.5% Na ₂ O,
K ₂ O 0.3 to 1.5%,
_TiO2 0.01-0.2%,
_ZrO2 from 2.0 to 3.5%,
The glass plate according to claim 4, containing 1.5 to 3.0% _SnO2 . The glass plate according to claim 1, which is glass-ceramic. The glass plate according to claim 1, which is chemically strengthened glass. The glass sheet according to claim 1, which is float glass. The glass plate according to claim 1, which has a visible light transmittance of 91.0% or more when converted to a thickness of 0.7 mm. A laminate comprising the glass plate according to claim 1 and a liquid crystal glass plate,
The lamination surface of the glass plate with the liquid crystal glass plate is the second main surface,
a laminate, wherein an absolute value of a difference between a refractive index of the second main surface of the glass plate measured with a prism coupler and a refractive index of the liquid crystal glass plate measured with a prism coupler is 0.001 to 0.20. A display device comprising the glass plate according to any one of claims 1 to 15 or the laminate according to claim 16.

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