WO2015046116A1

WO2015046116A1 - Glass plate

Info

Publication number: WO2015046116A1
Application number: PCT/JP2014/075016
Authority: WO
Inventors: 聡史宮坂; 正信白井; 亮祐加藤; 信彰井川; 山中　一彦; 泰夫林; 史朗谷井; 丈宜三浦
Original assignee: 旭硝子株式会社
Priority date: 2013-09-25
Filing date: 2014-09-22
Publication date: 2015-04-02
Also published as: JPWO2015046116A1; TW201518221A; JP6428630B2

Abstract

The present invention relates to a glass plate in which the fluorine concentration in one of the surfaces thereof that face each other in a thickness direction is greater than that in another of said surfaces thereof, said glass plate wherein the proportion of fluorine in a surface layer, said proportion being represented by formula (I), namely the proportion of fluorine in the surface layer = F_0-3/F_0-30, is at least 0.1 but less than 0.5, and F_0-3 represented by formula (II), namely F_0-3 = [the average fluorine concentration (mol%) at depths in the range of 0-3 µm in the surface having a high fluorine concentration, said average fluorine concentration being obtained using secondary ion mass spectrometry (SIMS)]× 3, is greater than 0.02. In formula (I), F_0-3 is obtained using formula (II). In formula (I), F_0-30 is obtained using formula (III), namely F_0-30 = [the average fluorine concentration (mol%) at depths in the range of 0-30 µm in the surface having a high fluorine concentration, said average fluorine concentration being obtained using SIMS]× 30.

Description

Glass plate

The present invention relates to a glass plate.

In recent years, in flat panel display devices such as mobile phones or personal digital assistants (PDAs), personal computers, televisions, in-vehicle navigation display devices, etc., in order to enhance the protection and aesthetics of the display, the area is wider than the image display portion. A thin plate-like cover glass is disposed on the front surface of the display.

Such a flat panel display device is required to be lightweight and thin, and accordingly, a cover glass used for display protection is also required to be thin.

However, as the thickness of the cover glass is reduced, the strength decreases, and the cover glass itself may be broken due to falling in use or while carrying it, which plays the original role of protecting the display device. There is a problem that it becomes impossible.

For this reason, the conventional cover glass chemically strengthens the glass manufactured by the float process (henceforth a float glass), forms the compressive-stress layer on the surface, and has improved the scratch resistance of the cover glass. .

It has been reported that the float glass is warped after chemical strengthening and the flatness is impaired (Patent Documents 1 to 3). The warpage includes a glass surface that is not in contact with a molten metal such as molten tin (hereinafter also referred to as a top surface) and a glass surface that is in contact with the molten metal (hereinafter also referred to as a bottom surface). It is said that this is caused by the different ways of entering chemical strengthening on both sides.

The warp of the float glass increases as the chemical strengthening becomes stronger. Therefore, when the surface compressive stress is made higher than ever, particularly 600 MPa or higher in order to meet the demand for high scratch resistance, the problem of warp becomes more obvious.

Patent Document 1 discloses a glass strengthening method in which the amount of ions entering the glass during chemical strengthening is adjusted by chemically strengthening after forming a SiO ₂ film on the glass surface.

Patent Documents

2 and 3 disclose a method of reducing warpage after chemical strengthening by setting the surface compressive stress on the top surface side within a specific range.

Further, conventionally, in order to reduce the problem of warpage, chemical strengthening is performed after removing a surface heterogeneous layer by reducing the strengthening stress due to chemical strengthening or grinding or polishing at least one surface of glass. There is a solution.

US Patent Application Publication No. 2011/0293928 International Publication No. 2007/004634 Japanese Unexamined Patent Publication No. Sho 62-191449

However, in the method of chemically strengthening after forming the SiO ₂ film on the glass surface described in Patent Document 1, the preheating conditions for chemical strengthening are limited, and depending on the conditions, the film quality of the SiO ₂ film changes and warps. May be affected. Further, as described in

Patent Documents

2 and 3, the method of setting the surface compressive stress on the top surface side in a specific range has a problem from the viewpoint of the strength of the glass.

Further, the method of grinding or polishing at least one surface of the glass before chemical strengthening has a problem from the viewpoint of improving productivity, and it is preferable to omit these grinding or polishing treatments.

Furthermore, if warping occurs to some extent after chemical strengthening, the gap between the glass and the stage becomes too large when printing the black frame of the cover glass, and the glass may not be adsorbed on the stage. When used for a cover glass with an integrated touch panel, ITO (Indium Tin Oxide) or the like may be formed in a large plate state in a later process. At that time, conveyance abnormalities such as glass coming into contact with the air knife in the chemical treatment tank or cleaning tank occur, warpage increases during ITO film formation, and the ITO film formation state at the periphery of the substrate is not appropriate. , May cause problems such as peeling off. In addition, in the case of a type in which a space exists between an LCD (Liquid Crystal Display) and a cover glass to which a touch panel is attached, if the cover glass has a certain amount of warpage, uneven brightness or Newton rings may occur.

Therefore, an object of the present invention is to provide a glass plate that can effectively suppress warping after chemical strengthening and can omit or simplify the polishing treatment before chemical strengthening.

The present inventors have found that by treating the glass surface with fluorine, it is possible to suppress a difference in the way of entering the chemical strengthening between one side and the other side of the glass and to reduce the warp after the chemical strengthening. Based on this finding, the present invention has been completed.

That is, the present invention is as follows.
1. A glass plate in which the fluorine concentration on one surface facing the thickness direction is larger than the fluorine concentration on the other surface, and the surface layer fluorine ratio represented by the following formula (I) is 0.1 or more and less than 0.5, And a glass plate in which F _0-3 represented by the following formula (II) is larger than 0.02.
Surface layer fluorine ratio = F _0-3 / F _0-30 (I)
In the formula (I), F _0-3 is determined by the following formula (II).
F _0-3 = [Average fluorine concentration (mol%) by secondary ion mass spectrometry (SIMS) at a depth of 0 to 3 μm on a surface with a large fluorine concentration] × 3 (II)
In the formula (I), F _0-30 is determined by the following formula (III).
F _0-30 = [Average fluorine concentration (mol%) by SIMS at a depth of 0 to 30 μm on a surface with a large fluorine concentration] × 30 (III)
2. 2. The glass plate according to item 1 above, wherein the surface layer fluorine ratio is 0.15 or more.
3. 3. The glass plate according to 1 or 2 above, wherein the surface layer fluorine ratio is 0.15 or more and 0.4 or less.
4). 4. The glass plate as described in 3 above, wherein the surface layer fluorine ratio is 0.3 or less.
5. 5. The glass plate according to any one of items 1 to 4, which satisfies the following formula (1): Here, the fluorine concentration is an average fluorine concentration (mol%) by SIMS having a depth of 1 to 24 μm.
0.38 ≦ ΔF / ΔH ₂ O (1)
In the formula (1), ΔF is an average fluorine concentration (mol%) by SIMS at a depth of 1 to 24 μm on a surface with a low fluorine concentration from an average fluorine concentration (mol%) by SIMS at a depth of 1 to 24 μm on a surface with a high fluorine concentration. %).
In formula (1), ΔH ₂ O is an average of SIMS having a depth of 1 to 24 μm on a surface having a high fluorine concentration from an average H ₂ O concentration (mol%) of SIMS having a depth of 1 to 24 μm on a surface having a low fluorine concentration. The absolute value of the value obtained by subtracting the H ₂ O concentration (mol%).
6). 6. The glass plate according to any one of items 1 to 5, which satisfies the following formula (2). Here, the fluorine concentration is an average fluorine concentration (mol%) by SIMS having a depth of 1 to 24 μm.
5 ≦ x (2)
In the formula (2), x is the maximum depth (μm) in which the slope at an arbitrary depth x _i (μm) satisfies the following formula (3) in the fluorine concentration profile by SIMS.
[F (x _i +0.1) −F (x _i )] / 0.1 = −0.015 (3)
In formula (3), F (x _i ) represents the fluorine concentration (mol%) by SIMS at the depth x _i (μm).
7). 7. The glass plate according to any one of items 1 to 6, which is a glass plate produced by a float process.
8). 8. The glass plate according to any one of items 1 to 7, which has a thickness of 1.5 mm or less.
9. 9. The glass plate according to any one of items 1 to 8, wherein the thickness is 0.8 mm or less.
10. 10. The glass plate according to any one of items 1 to 9, wherein the surface roughness Ra is 2.5 nm or less.
11. 11. The glass plate according to any one of the preceding items 1 to 10, wherein a concave portion having a diameter of 10 nm or more does not exist on the surface having a larger fluorine concentration, or the concave portions exist at a density of 6 pieces / μm ² or less.
12 12. A glass plate obtained by chemically strengthening the glass plate according to any one of 1 to 11 above.
13. A flat panel display device provided with a cover glass, wherein the cover glass is the glass plate according to item 12 above.

The glass plate of the present invention has a surface treated with fluorine, thereby suppressing a difference in the way of chemical strengthening between one side and the other side of the glass, and a desired stress value due to chemical strengthening. Can be a value. Further, even if the polishing treatment before chemical strengthening is simplified or omitted, the warp of the glass after chemical strengthening can be reduced and excellent flatness can be obtained.

FIG. 1 is a diagram schematically showing a double-flow type injector that can be used in the present invention. FIG. 2 is a diagram schematically showing a single-flow injector that can be used in the present invention. FIG. 3 is a cross-sectional view of a flat panel display used as a cover glass for a flat panel display after chemically strengthening the chemically strengthened float glass of the present invention. FIG. 4 (a) shows a schematic explanatory diagram of a method for treating the surface of a glass ribbon by supplying a gas containing a molecule having fluorine atoms in the structure thereof by a beam in the production of a glass plate by a float method. FIG. 4B is a cross-sectional view taken along the line AA in FIG. FIGS. 5A to 5D are cross-sectional views of beams that can be adjusted by dividing the amount of gas into three in the width direction of the glass ribbon. FIGS. 6A to 6C show typical fluorine concentration profiles by SIMS of a fluorine-treated aluminosilicate glass. FIGS. 7 (a) to (c) show typical H ₂ O concentration profiles by SIMS of aluminosilicate glass. FIG. 8 shows a typical IR spectrum of an aluminosilicate glass. FIG. 9 is a diagram showing the correlation between ΔF / ΔH ₂ O and the amount of warp displacement of the glass. FIG. 10 (a) shows a typical fluorine concentration profile by SIMS of aluminosilicate glass. FIG. 10B is a diagram in which the horizontal axis represents the depth and the vertical axis represents the slope at an arbitrary point x _i represented by the formula (a). FIG.10 (c) shows the figure which expanded the dotted-line part in FIG.10 (b). FIG. 11 is an explanatory diagram of a mechanism for generating recesses by HF processing. FIG. 12 is a perspective view of the apparatus used in the example. Example 4

1. Glass plate In the present invention, the “glass plate” includes those in which molten glass is formed into a plate shape. For example, a so-called glass ribbon in a float bath is also a glass plate. The warpage after chemical strengthening of the glass plate is caused by the difference in the way of chemical strengthening on one side and the other side of the glass plate. Specifically, for example, in the case of float glass, chemical strengthening is performed on the glass surface (top surface) that is not in contact with the molten metal (usually tin) and the glass surface (bottom surface) that is in contact with the molten metal during float forming. Warping after chemical strengthening occurs due to the difference in the way of entering.

According to the glass plate of the present invention, typically, one side of the glass plate is treated with fluorine to adjust the diffusion rate of ions on one side and the other side of the glass plate, It is possible to adjust the way of chemical strengthening on the other side and the other side. Therefore, the glass plate of the present invention can reduce the warpage of the glass plate after chemical strengthening without adjusting the strengthening stress or without performing processing such as grinding and polishing before the chemical strengthening treatment.

As a mechanism that can reduce the warpage after chemical strengthening by treating the surface of the glass plate with fluorine, the following phenomenon is considered to have occurred.
(1) Relaxation is promoted by fluorine taken into the surface of the glass, and CS (compressive stress) of the surface treated with fluorine is reduced.
(2) Ion exchange is inhibited by fluorine taken into the surface of the glass, and DOL (depth of layer, compression stress depth) of the surface treated with fluorine decreases.
(3) The dealkalization of the glass occurs by the fluorine treatment.
(4) The main component of the glass surface is changed by the fluorine treatment, and Si in the glass is reduced from the glass surface as SiF ₄ or H ₂ SiF ₆ , so that the stress is changed.
(5) The warp is reduced by suppressing the dehydration from the glass surface or the intrusion of water by the fluorine treatment.

1A. Parameters defining the fluorine concentration distribution in the proper thickness direction for improving warpage Warpage due to chemical strengthening of glass is caused by the difference in how chemical strengthening is applied on the top and bottom surfaces. By adding fluorine to the glass surface layer, warpage due to chemical strengthening of the glass is improved due to various factors, but the following parameters are set for the fluorine concentration distribution added to the glass in consideration of the penetration depth at the top surface.

The glass plate of the present invention is a glass plate in which the fluorine concentration on one surface facing in the thickness direction is larger than the fluorine concentration on the other surface, and the surface layer fluorine ratio represented by the following formula (I) is 0.1 or more It is a glass plate that is less than 0.5 and F _0-3 represented by the following formula (II) is greater than 0.02.
Surface layer fluorine ratio = F _0-3 / F _0-30 (I)

In the formula (I), F _0-3 is the fluorine amount on the glass surface (depth 0 to 3 μm from the glass surface), and is determined by the following formula (II).
F _0-3 = [Average fluorine concentration (mol%) by SIMS at a depth of 0 to 3 μm on a surface with a large fluorine concentration] × 3 (II)
In the formula (I), F _0-30 is the amount of fluorine taken into the glass by the fluorine treatment, and is determined by the following formula (III).
F _0-30 = [Average fluorine concentration (mol%) by SIMS at a depth of 0 to 30 μm on a surface with a large fluorine concentration] × 30 (III)

The average fluorine concentration is calculated from the profile according to the following procedures (a1) to (a3) after measuring the fluorine concentration profile in the glass with a SIMS apparatus. 6 (a) to 6 (c) show typical fluorine concentration profiles by SIMS of a fluorine-treated aluminosilicate glass.
(A1) Measure the fluorine concentration profile by SIMS of a standard sample with a known concentration and a sample to be measured [FIG. 6A].
(A2) A calibration curve is created from the measurement results of the standard sample, and a coefficient for converting ¹⁹ F / ³⁰ Si into a fluorine concentration (mol%) is calculated [FIG. 6 (b)].
(A3) The fluorine concentration (mol%) of the sample to be measured is obtained from the coefficient calculated in step (a2). For example, the average fluorine concentration (mol%) by SIMS at a depth of 0 to 3 μm is a value obtained by integrating the fluorine concentrations at a depth of 0 to 3 μm and dividing by the depth of 3 μm [FIG. 6 (c)].
The average fluorine concentration (mol%) by SIMS at a depth of 0 to 30 μm can be obtained in the same manner.

When the surface layer fluorine ratio is 0.1 or more, the warp of the glass after chemical strengthening can be effectively suppressed. The surface layer fluorine ratio is 0.1 or more, and preferably 0.15 or more.

The surface layer fluorine ratio is less than 0.5, preferably 0.4 or less, and more preferably 0.3 or less. When the surface layer fluorine ratio is 0.4 or less, particularly 0.3 or less, the following effects (1) to (3) are remarkable and more preferable.

(1) Warpage due to chemical strengthening of glass is caused by a difference in compressive stress between both glass surfaces. In general, plate glass produced by the float process has a different composition distribution in the depth direction on the front and back surfaces. Therefore, the method of entering the compressive stress in the depth direction of the glass front and back surfaces due to chemical strengthening is also different, resulting in warping of the glass. This warpage depends on the thickness of the compressive stress layer (hereinafter referred to as DOL). On the other hand, it has been found from the examination results of the present inventors that fluorine in the glass has an effect of relieving the compressive stress generated by chemical strengthening. Therefore, by introducing fluorine into the glass surface, the above-described difference in compressive stress between the front and back surfaces of the glass can be reduced, and the warpage can be reduced. At this time, of the compressive stress generated up to the depth of DOL, stress relaxation occurs in a region up to the fluorine penetration depth. For this reason, when the fluorine penetration depth is deep, when the DOL is fluctuated, the fluctuation of the ratio of the fluorine penetration depth to the compression stress depth is small, so the fluctuation of stress relaxation is small. As a result, the fluctuation of the warpage improvement amount is also reduced. For the above reasons, when the surface layer fluorine ratio is 0.4 or less, particularly 0.3 or less by fluorine treatment, the penetration depth of fluorine into the glass is increased, and the fluorine concentration on the outermost surface of the glass is reduced. It is possible to suppress the DOL dependency of glass warpage due to strengthening.
(2) When the glass is polished or etched after the glass is subjected to fluorine treatment, fluorine on the glass surface is reduced, and the warp reduction effect after chemical strengthening due to the fluorine treatment of the glass is reduced. Even if the glass is polished or etched before chemical strengthening by making the surface layer fluorine ratio 0.4 or less, especially 0.3 or less by fluorine treatment, and increasing the penetration depth of fluorine into the glass, fluorine treatment It is possible to sufficiently ensure the effect of reducing the warpage of the glass after chemical strengthening.
(3) When the fluorine concentration on the outermost surface is increased by subjecting one surface of the glass to fluorine treatment, there is a problem that stress is relaxed only by one surface due to fluorine and CS is difficult to enter. When the surface fluorine ratio is 0.4 or less, particularly 0.3 or less by the fluorine treatment, the fluorine concentration on the outermost surface is prevented from increasing, and ΔCS (the value of CS on one surface facing the thickness direction and the other surface) The difference in the CS value of the glass) can be brought close to 0, so that the warpage due to chemical strengthening can be reduced and a glass excellent in strength can be obtained.

In order to set the surface layer fluorine ratio to 0.4 or less, particularly 0.3 or less, as will be described later, a gas or liquid containing molecules in which fluorine atoms are present in the structure (hereinafter also referred to as fluorine-containing fluid). ) Is supplied to the surface of the glass plate being conveyed, and the surface temperature of the glass plate when the surface is treated is preferably (Tg + 230 ° C.) or higher, where Tg is the glass transition temperature of the glass plate. A method of preferably (Tg + 300 ° C.) or higher is mentioned.

In addition, as a method for setting the surface layer fluorine ratio to 0.4 or less, a method of increasing the treatment time with fluorine, a method of volatilizing the surface fluorine by subjecting the glass to a heat treatment and then performing a heat treatment again, etc. Can be mentioned.

The secondary ion intensity I _M1 of the isotope M ₁ of the element M in SIMS is the primary ion intensity I _P , the sputtering rate Y of the matrix, the concentration C _{M of the} element _M (ratio to the total concentration), and the existence probability of the isotope M ₁ It is proportional to α ₁ , the secondary ionization rate β _{M of} the element M, and the transmission efficiency η (including the detection efficiency of the detector) of the mass spectrometer.
I _M1 = A · I _P · Y · C _M · α ₁ · β _M · η (Formula w)

Here, A is the ratio of the secondary ion detection area to the scanning range of the primary ion beam. In general, it is impossible to determine the absolute value for the hard beta _M determine the η devices. Therefore, η is eliminated by using a main component element or the like in the same sample as a reference element and taking a ratio with (formula w).

Here, when the reference element is R and its isotope is R _j , (formula x) is obtained.
I _M1 / I _Rj = (C _M · α ₁ · β _M ) / (C _R · α _j · β _R ) = C _M / K (Formula x)
Here, K is a relative sensitivity factor of the element M with respect to the element R.
K = ( _CR * [alpha] _j * [beta] _R ) / ([alpha] ₁ * [beta] _M ) (formula y)
In this case, the concentration of the element M is obtained from (Expression z).
C _M = K · I _M1 / I _Rj (formula z)

In the present invention, F corresponds to M ₁ and Si corresponds to R _j . Therefore, (Equation x) ratio of the intensities from the (F / Si) is equal to fluorine concentration _{C M} in divided by K. That is, F / Si is a direct indicator of fluorine concentration.

Examples of SIMS analysis conditions include the following conditions. The analysis conditions shown below are examples, and should be changed as appropriate depending on the measurement device, sample, and the like. Further, the depth of the horizontal axis of the profile in the depth direction obtained by SIMS can be obtained by measuring the depth of the analysis crater with a stylus type film thickness meter (for example, Dektak 150 manufactured by Veeco).

(Analysis conditions)
Primary ion species: Cs ⁺
Primary ion incident angle: 60 °
Primary acceleration voltage: 5 kV

More specific analysis conditions include, for example, the following conditions.
(Analysis conditions)
Measuring device: Secondary ion mass spectrometer having a quadrupole mass analyzer Primary ion species: Cs ⁺
Primary acceleration voltage: 5.0 kV
Primary ion current: 1μA
Primary ion incident angle (angle from the direction perpendicular to the sample surface): 60 °
Raster size: 200x200μm ²
Detection area: 40 × 40 μm ²
Secondary ion polarity: Electron gun for negative neutralization Use: Yes

As a secondary ion mass spectrometer having a quadrupole mass spectrometer, for example, ADEPT 1010 manufactured by ULVAC-PHI can be mentioned.

1B. Parameters for defining an appropriate fluorine addition amount for improving warpage Warpage due to chemical strengthening of glass is caused by a difference in the way of chemical strengthening on the top surface and the bottom surface. The difference in the way of chemical strengthening is largely influenced by the amount of moisture in the glass. Addition of fluorine to the glass surface layer improves the warpage due to chemical strengthening of the glass due to various factors, but considering the difference in moisture content between the top and bottom surfaces, the appropriate amount of fluorine added to the glass is as follows: Set the parameters.

The glass plate of the present invention is a glass plate in which the fluorine concentration on one surface facing in the thickness direction is larger than the fluorine concentration on the other surface, and preferably satisfies the following formula (1).
0.38 ≦ ΔF / ΔH ₂ O (1)

In the formula (1), ΔF is an average fluorine concentration (mol%) by SIMS at a depth of 1 to 24 μm on a surface with a low fluorine concentration from an average fluorine concentration (mol%) by SIMS at a depth of 1 to 24 μm on a surface with a high fluorine concentration. %). The average fluorine concentration can be obtained by the above procedure.

In formula (1), ΔH ₂ O is an average of SIMS having a depth of 1 to 24 μm on a surface having a high fluorine concentration from an average H ₂ O concentration (mol%) of SIMS having a depth of 1 to 24 μm on a surface having a low fluorine concentration. The absolute value of the value obtained by subtracting the H ₂ O concentration (mol%).

The average H ₂ O concentration (mol%) is calculated from the profile according to the following procedures (b1) to (b3) after measuring the fluorine concentration profile in the glass with a SIMS apparatus. FIGS. 7A to 7C show typical H ₂ O concentration profiles by SIMS of aluminosilicate glass.
(B1) concentration is measured of _{H 2} O concentration profiles by SIMS of the known standard samples and measuring sample [Fig. 7 (a)].
(B2) A calibration curve is created from the measurement result of the standard sample, and a coefficient for converting ¹ H / ³⁰ Si into H ₂ O concentration (mol%) is calculated [FIG. 7 (b)].
(B3) The H ₂ O concentration (mol%) of the measurement target sample is obtained from the coefficient calculated in step (b2). The average H ₂ O concentration (mol%) by SIMS at a depth of 1 to 24 μm is a value obtained by integrating the H ₂ O concentration at a depth of 1 to 24 μm and dividing by 23 [FIG. 7 (c)].
The absolute value of the difference between the values obtained by calculating the average H ₂ O concentration (mol%) by SIMS at a depth of 1 to 24 μm for both surfaces facing in the thickness direction of the glass by the steps (b1) to (b3) is ΔH ₂ O It becomes.

In the step (b2), the H ₂ O concentration in the standard sample is obtained by polishing both the top surface and the bottom surface of the sample to be measured so that there is no distribution of the H ₂ O concentration in the thickness direction of the glass. An IR spectrum of the glass is obtained using an FT-IR apparatus, and the H ₂ O concentration (mol%) is calculated from the intensity of the peak due to water in the glass. A typical IR spectrum of an aluminosilicate glass is shown in FIG.

That is, the calculation of the H ₂ O concentration C _H2O (mol%) in the glass is based on the Lambert-Beer law represented by the formula (i), d: specific gravity of glass (g / cm ³ ), Mw: average molecular weight of glass. And is obtained by equation (ii).

A _H2O = ε _H2O × C × l (i)
ε _H2O : molar extinction coefficient of H ₂ O in glass (L mol− ¹ cm ⁻¹ )
C: H ₂ O concentration in glass (mol L ⁻¹ )
l: Optical path length (cm)

As shown in FIG. 9, ΔF / ΔH ₂ O and the warp displacement amount of the glass show a correlation, and by setting 0.38 ≦ ΔF / ΔH ₂ O, the warp after chemical strengthening is effectively suppressed. Can do. ΔF / ΔH ₂ O is preferably 0.38 or more, more preferably 1 or more, and even more preferably 2 or more. If ΔF / ΔH ₂ O is less than 0.38, no significant difference is observed in the warpage displacement, which is inappropriate. Moreover, it is practically preferable that ΔF / ΔH ₂ O is 15 or less.

1C. Parameters defining the fluorine penetration depth for warpage improvement Adding fluorine to the glass surface layer improves the warpage after chemical strengthening, but the following parameters are set in consideration of the fluorine penetration depth.

The glass plate of the present invention is a glass plate in which the fluorine concentration on one surface facing in the thickness direction is larger than the fluorine concentration on the other surface, and preferably satisfies the following formula (2).
5 ≦ x (2)
In the formula (2), x is the maximum depth (μm) in which the slope at an arbitrary depth x _i (μm) satisfies the following formula (3) in the fluorine concentration profile by SIMS.
[F (x _i +0.1) −F (x _i )] / 0.1 = −0.015 (3)
In formula (3), F (x _i ) represents the fluorine concentration (mol%) by SIMS at the depth x _i (μm).

FIG. 10A shows a typical fluorine concentration profile by SIMS of a fluorine-treated aluminosilicate glass. FIG. 10B is a graph plotting the depth at the horizontal axis and the slope at an arbitrary point x _i represented by the following equation (a) on the vertical axis. In the following formula (a), F (x) represents the fluorine concentration (mol%) at the point x.
[F (x _i + Δx) −F (x _i )] / Δx (a)
When Δx is 0.1, the maximum depth x (μm) at which the slope represented by the formula (a) is −0.015 is preferably 5 or more, more preferably 10 or more. preferable. When x is less than 5, there is no significant difference in warpage displacement.

FIG. 10 (c) is an enlarged view of the dotted line portion of the graph of FIG. 10 (b). For example, in FIG. 10C, when Δx is 0.1, the maximum depth x (μm) at which the slope represented by the formula (a) is −0.015 is 6.5.

2. The manufacturing method of a glass plate The manufacturing method of the glass plate of this invention is not specifically limited, As long as it has a composition which can be strengthened by a chemical strengthening process, the thing of various compositions can be used. For example, appropriate amounts of various raw materials are prepared, heated and melted, then homogenized by defoaming or stirring, and formed into a plate shape by a well-known float method, downdraw method (for example, fusion method) or press method, After slow cooling, it is cut into a desired size and polished to produce. Among these production methods, glass produced by the float process is preferable because the improvement of warpage after chemical strengthening, which is the effect of the present invention, is particularly easily exhibited.

Specific examples of the glass plate used in the present invention include a glass plate typically made of soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, or borosilicate glass.

Among these, glass having a composition containing Al is preferable. When Al coexists with Al, it takes 4-coordination and participates in the formation of a network that becomes a glass skeleton like Si. When tetracoordinate Al increases, movement of alkali ions becomes easy, and ion exchange easily proceeds during chemical strengthening treatment.

The thickness of the glass plate is not particularly limited, and examples thereof include 2 mm, 0.8 mm, 0.73 mm, 0.7 mm, 0.56 mm, and 0.4 mm. In order to carry out, it is usually preferably 5 mm or less, more preferably 3 mm or less, further preferably 1.5 mm or less, and particularly preferably 0.8 mm or less.

Usually, the warp amount after chemical strengthening of a 0.7 mm thick glass plate is required to be 40 μm or less. When a 90 mm square glass plate has a CS of 750 MPa and a DOL of 40 μm, the amount of warpage after chemical strengthening is about 130 μm. On the other hand, the amount of warpage of the glass plate after chemical strengthening is inversely proportional to the square of the plate thickness, so the amount of warpage when the thickness of the glass plate is 2.0 mm is about 16 μm, and the warpage is substantially a problem. Never become. Therefore, the problem of warpage after chemical strengthening may occur when the thickness of the glass plate is less than 2 mm, typically 1.5 mm or less.

The composition of the glass plate of the present invention is a composition expressed in mol%, SiO ₂ is 50 to 80%, Al ₂ O ₃ is 0.1 to 25%, Li ₂ O + Na ₂ O + K ₂ O is 3 to 30%. , A glass containing 0 to 25% MgO, 0 to 25% CaO and 0 to 5% ZrO ₂ , but is not particularly limited. More specifically, the following glass compositions may be mentioned. For example, “containing 0 to 25% of MgO” means that MgO is not essential but may contain up to 25%. The glass of (i) is contained in soda lime silicate glass, and the glass of (ii) and (iii) is contained in aluminosilicate glass.
(I) A composition expressed in mol%, with SiO ₂ being 63 to 73%, Al ₂ O ₃ being 0.1 to 5.2%, Na ₂ O being 10 to 16%, and K ₂ O being 0 to 1. Glass (ii) containing 5%, MgO 5 to 13% and CaO 4 to 10%. The composition expressed as mol% is SiO ₂ 50 to 74%, Al ₂ O ₃ 1 to 10%, Na ₂ Contains 6-14% O, 3-11% K ₂ O, 2-15% MgO, 0-6% CaO and 0-5% ZrO ₂ , and contains SiO ₂ and Al ₂ O ₃ composition total 75% or less, and displayed in the total content of Na ₂ O content and _{K 2} O 12 to 25% glass (iii) mol percent total of 7 to 15% of the content of MgO and CaO 0 but the SiO ₂ 68 ~ 80%, the _{_{Al 2 O 3 4 ~ 10%}} , a Na ₂ O 5 ~ 15%, the _{K 2} O 1%, the MgO 4 ~ 15% and ZrO ₂ are compositions displaying 0-1% glass containing (iv) mol%, a SiO ₂ 67 ~ 75%, the _{_{Al 2 O 3 0 ~ 4%}} , Na ₂ O the 7 ~ 15% _{K 2} O 1-9% of MgO 6 ~ 14% and the ZrO ₂ and contains 0 to 1.5% total content of SiO ₂ and _Al 2 _{O 3} is 71 -75%, the total content of Na ₂ O and K ₂ O is 12-20%, and when containing CaO, the composition expressed in terms of glass (v) mol% whose content is less than 1%, SiO ₂ 62-72%, Al ₂ O ₃ 1-7%, Na ₂ O 13-19%, K ₂ O 0-4%, MgO 8-16%, CaO 0-6% and Glass containing 0 to 3% of ZrO ₂ and CaO / MgO of 0.5 or less

In the method for producing a glass plate of the present invention, surface treatment is performed by bringing a fluorine-containing fluid into contact with at least one surface of the glass plate or the glass ribbon. When the surface treatment is performed by bringing a fluorine-containing fluid into contact with at least one surface of the glass ribbon, the temperature of the glass ribbon is preferably 650 ° C. or higher. By setting the temperature to 650 ° C. or higher, it is possible to reduce the amount of warpage of the glass after chemical strengthening while suppressing the generation of recesses described later.

Examples of the fluorine-containing fluid include hydrogen fluoride (HF), flon (for example, chlorofluorocarbon, fluorocarbon, hydrochlorofluorocarbon, hydrofluorocarbon, and halon), hydrofluoric acid, fluorine alone, trifluoroacetic acid, and carbon tetrafluoride. , Silicon tetrafluoride, phosphorus pentafluoride, phosphorus trifluoride, boron trifluoride, nitrogen trifluoride, chlorine trifluoride and the like, but are not limited to these gases or liquids.

Among these, hydrogen fluoride, chlorofluorocarbon or hydrofluoric acid is preferable because of its high reactivity with the glass plate surface. Moreover, you may mix and use 2 or more types among these gases. Further, since the oxidizing power is too strong in the float bath, it is preferable not to use fluorine alone.

When a liquid is used, the liquid may be supplied to the glass plate surface by spray coating, for example, or may be supplied to the glass plate surface after vaporizing the liquid. Moreover, you may dilute with another liquid or gas as needed.

The fluorine-containing fluid may contain a liquid or a gas other than those liquids or gases, and is preferably a liquid or a gas that does not react with molecules having fluorine atoms at room temperature.

Examples of the liquid or gas include, but are not limited to, N ₂ , air, H ₂ , O ₂ , Ne, Xe, CO ₂ , Ar, He, and Kr. Moreover, 2 or more types of these gases can also be mixed and used.

As a gas carrier gas containing molecules having fluorine atoms in its structure, it is preferable to use an inert gas such as N ₂ or argon. Further, the gas containing a molecule having a fluorine atom in its structure may further contain SO ₂ . SO ₂ is used when a glass plate is continuously produced by a float process or the like, and has a function of preventing wrinkles from being generated on the glass due to the conveyance roller coming into contact with the glass plate in the slow cooling region. Moreover, the gas decomposed | disassembled at high temperature may be included.

Furthermore, the fluorine-containing fluid may contain water vapor or water. Water vapor can be extracted by bubbling an inert gas such as nitrogen, helium, argon, carbon dioxide in heated water. When a large amount of water vapor is required, it is also possible to take a method in which water is sent directly to the vaporizer and vaporized directly. In the following description, a case where HF gas is used as the fluorine-containing fluid will be described as an example.

Specific examples of the method for producing a glass plate of the present invention include a method for producing a glass plate represented by the float process. In the float process, a glass manufacturing apparatus having a melting furnace for melting glass raw materials, a float bath for floating glass on a molten metal (such as tin) to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon Is used to produce a glass plate.

When glass is formed on a molten metal (tin) bath, HF gas is supplied from the side not touching the metal surface to the glass plate conveyed on the molten metal bath to treat the surface of the glass plate. May be. In the slow cooling region following the molten metal (tin) bath, the glass plate is conveyed by a roller.

FIG. 4 (a) shows a schematic explanatory diagram of a method for processing a glass surface by supplying HF gas in the production of a glass plate by a float method.

In a float bath in which molten glass is floated on a molten metal (tin or the like) to form the glass ribbon 101, HF gas is blown onto the glass ribbon 101 by a beam 102 inserted into the float bath. As shown in FIG. 4A, the HF gas is preferably blown onto the glass ribbon 101 from the side where the glass ribbon 101 does not touch the molten metal surface. An arrow Ya indicates a direction in which the glass ribbon 101 flows in the float bath.

When the glass transition point is 550 ° C. or higher, the glass ribbon 101 is preferably 650-970 ° C. when the HF gas is blown onto the glass ribbon 101 by the beam 102. Further, the position of the beam 102 may be upstream or downstream of the radiation gate 103. The amount of HF gas blown onto the glass ribbon 101 is preferably 1 × 10 ⁻⁶ to 5 × 10 ⁻³ mol / cm ² of the glass ribbon.

Fig. 4 (b) shows a cross-sectional view along the line AA in Fig. 4 (a). The HF gas blown to the glass ribbon 101 by the beam 102 from the Y1 direction flows in from “IN” and flows out from the “OUT” direction. That is, it moves in the directions of arrows Y4 and Y5 and is exposed to the glass ribbon 101. The HF gas that has moved in the direction of arrow Y4 flows out from the direction of arrow Y2, and the HF gas that has moved in the direction of arrow Y5 flows out from the direction of arrow Y3.

The amount of warpage of the glass plate after chemical strengthening may change depending on the position of the glass ribbon 101 in the width direction. In such a case, it is preferable to adjust the amount of HF gas. That is, it is preferable to increase the amount of blowing HF gas at a position where the amount of warping is large, and to reduce the amount of blowing HF gas at a position where the amount of warping is small.

When the amount of warpage of the glass plate after chemical strengthening changes depending on the position of the glass ribbon 101, the structure of the beam 102 is made so that the HF gas can be adjusted in the width direction of the glass ribbon 101. The amount of warpage may be adjusted in the width direction.

As a specific example, FIG. 5A shows a cross-sectional view of a beam 102 that adjusts the amount of HF gas by dividing it into I to III in the width direction 110 of the glass ribbon 101. The gas systems 111 to 113 are divided by

partition walls

114 and 115, and HF gas is caused to flow out from the gas blowing holes 116 and sprayed onto the glass.

The arrow in Fig.5 (a) shows the flow of HF gas. The arrows in FIG. 5B indicate the flow of HF gas in the gas system 111. The arrows in FIG. 5C indicate the flow of HF gas in the gas system 112. An arrow in FIG. 5D indicates the flow of HF gas in the gas system 113.

Examples of a method for supplying a fluorine-containing fluid such as HF gas to the glass surface include a method using an injector and a method using an introduction tube.

1 and 2 are schematic views of an injector used for the surface treatment of a glass plate that can be used in the present invention. FIG. 1 is a diagram schematically showing a double-flow type injector that can be used in the present invention. FIG. 2 is a diagram schematically showing a single-flow injector that can be used in the present invention.

HF gas is discharged from the central slit 1 and the outer slit 2 toward the glass plate 20, flows on the glass plate 20 through the flow path 4, and is exhausted from the exhaust slit 5. In addition, the code | symbol 21 in FIG.1 and FIG.2 is a direction through which the glass plate 20 flows, and is parallel to the flow path 4. FIG.

When the fluorine-containing fluid supplied from the injector is a gas, the distance between the gas discharge port of the injector and the glass plate is preferably 50 mm or less.

By setting the distance to 50 mm or less, the gas can be prevented from diffusing into the atmosphere, and a sufficient amount of gas can reach the glass plate with respect to the desired gas amount. On the other hand, if the distance from the glass plate is too short, for example, when the glass plate produced by the float process is processed online, the glass plate and the injector may come into contact with each other due to the fluctuation of the glass ribbon.

Further, when the fluorine-containing fluid supplied from the injector is a liquid, there is no particular limitation on the distance between the liquid discharge port of the injector and the glass plate, and it may be arranged so that the glass plate can be processed uniformly.

The injector may be used in any manner such as double flow or single flow, and two or more injectors may be arranged in series in the flow direction of the glass plate to treat the glass plate surface. As shown in FIG. 1, the double-flow injector is an injector in which the gas flow from discharge to exhaust is equally divided in the forward direction and the reverse direction with respect to the moving direction of the glass plate.

This double-flow injector is common and is also known for use in producing low reflection glass. For example, asahi glass soda lime silicate glass (glass transition point 560 ° C.) having a thickness of 1.8 mm reheated to 600 ° C., HF gas from the central slit 1 is 1.12 SLM (liters per minute as standard gas) and a nitrogen _{(N 2)} gas was mixed gas 9SLM heated to 0.99 ° C. flow rate 64cm / s, to blow 45.5SLM the _{N 2} gas from the outer slit 2, which may be used. The surface roughness (arithmetic mean roughness) Ra of the glass surface sprayed with HF gas in this manner is 30.6 nm, and the value of x described above is 2.5 μm.

As shown in FIG. 2, the single-flow injector is an injector in which the gas flow from discharge to exhaust is fixed in either the forward direction or the reverse direction with respect to the moving direction of the glass plate. When a single-flow injector is used, it is preferable that the gas flow on the glass plate and the moving direction of the glass plate are the same in terms of airflow stability.

In addition, a fluorine-containing fluid supply port, a gas generated by reacting with an unreacted fluorine-containing fluid and a glass plate, or a gas exhaust port generated by reacting two or more kinds of gases among fluorine-containing fluids It is preferable that it exists in the surface of the same side of a glass plate.

In the present invention, the surface temperature of the glass plate when the fluorine-containing fluid is supplied to the surface of the glass plate being conveyed to treat the surface is (Tg + 50) when the glass transition temperature of the glass plate is Tg. ° C) to (Tg + 460 ° C), preferably (Tg + 150 ° C) to (Tg + 460 ° C), more preferably (Tg + 230 ° C) to (Tg + 460 ° C).

In molding in the float bath, the temperature is usually higher on the upstream side in the direction in which the glass ribbon flows. The diffusion of fluorine in the glass is more active as the temperature is higher, that is, as the viscosity is lower. Therefore, the fluorine treatment in the float bath is effective when performed upstream in order to increase the penetration depth of fluorine. Or the same effect can be acquired also by raising the temperature of the glass ribbon of a process position.

However, when processing on the upstream side, the glass ribbon may go through a process of thinning in the float bath after processing. In that case, since the penetration depth of fluorine becomes shallower with the glass ribbon, the penetration depth of fluorine in the finally obtained glass plate is shallower than the penetration depth of fluorine in the glass plate that has been processed the same downstream. There is. Therefore, when the fluorine treatment is performed in the float bath, it is not always effective to provide the treatment position significantly upstream in order to increase the fluorine penetration depth.

In order to suppress the occurrence of recesses in the glass plate and obtain the effect of improving the warp after chemical strengthening, the surface temperature of the glass plate during the fluorine treatment is preferably (Tg + 90) ° C. or higher. Regardless of the above, the surface temperature of the glass plate is preferably more than 650 ° C. When the glass plate has a surface temperature of 650 ° C. or lower and is subjected to fluorine treatment, recesses are likely to occur. In the present specification, the concave portion is a minute hole generated on the surface of a glass plate that can be visually recognized by an SEM (Scanning Electron Microscope). When the concave portion is generated in the glass plate, the strength of the glass plate is lowered.

The concave portion typically shows a shape that expands in a substantially spherical bag shape after being reduced in diameter from the surface. The diameter of such a recess represents the diameter of the constricted portion between the reduced diameter portion and the bag-like portion, and can be observed by SEM or the like. The depth of the concave portion represents the depth from the glass surface to the deepest portion of the bag-like portion, and can be measured by cross-sectional SEM observation or the like.

The concave portion in the present invention means a size or diameter of 10 nm or more, usually 20 nm or more, and typically 40 nm or less. The depth of the recess is usually 10 nm or more, and typically 150 nm or less.

If the surface having the higher fluorine concentration has recesses with a density of more than 7 / μm ² , the strength of the chemically strengthened glass plate may be lowered. Therefore, even if there are recesses, the density is preferably 6 / μm ² or less, more preferably 4 / μm ² or less, and most preferably 0 / μm ² . Note that the average interval between the recesses when the recess density is 6 / μm ² is 460 nm.

FIG. 11 shows an explanatory diagram of the mechanism of the recess generation by HF treatment. When glass is treated with HF, fluoride is generated and volatilized [FIG. 11 (a)]. When the rate of fluoride generation by the reaction of HF and glass is faster than the rate of volatilization of the generated fluoride, it is generated. The remaining fluoride remains on the treated surface [FIG. 11 (b)], and the molten fluoride grows while etching and the molten salt decreases [FIG. 11 (c)]. As a result, the final product becomes a recess. It is thought that [FIG. 11 (d)] is observed.

Regarding the gas flow rate, the case where HF is used as the fluorine-containing fluid will be described as an example. When processing a glass plate with HF, the higher the HF flow rate, the greater the warp improvement effect during the chemical strengthening treatment, which is preferable. When the total gas flow rate is the same, the higher the HF concentration, the better the warp improvement effect during the chemical strengthening treatment. Becomes larger.

When the total gas flow rate and the HF gas flow rate are constant, the longer the time for processing the glass plate, the greater the warp improvement effect during the chemical strengthening process. For example, when the glass plate surface is treated with HF gas after the glass plate is heated, the warpage after chemical strengthening is improved as the conveyance speed of the glass plate is lower. Even in facilities where the total gas flow rate and HF flow rate cannot be controlled well, the warpage after chemical strengthening can be improved by appropriately controlling the conveying speed of the glass plate.

3. Chemical strengthening Chemical strengthening is performed by ion exchange at a temperature below the glass transition point to convert an alkali metal ion (typically Li ion or Na ion) having a small ion radius on the glass surface to an alkali metal ion having a larger ion radius. This is a process of forming a compressive stress layer on the glass surface by exchanging with (typically K ions). The chemical strengthening treatment can be performed by a conventionally known method.

In the present invention, a glass plate with improved warpage after chemical strengthening can be obtained by chemically strengthening the glass plate into which fluorine has been introduced. The amount of warpage (warpage variation) of the glass plate after chemical strengthening relative to the glass plate before chemical strengthening is measured by a three-dimensional shape measuring machine (for example, manufactured by Mitaka Kogyo Co., Ltd.), or surface roughness and contour shape measurement It can be measured with a machine (for example, manufactured by Tokyo Seimitsu Co., Ltd.).

In the present invention, the improvement of warpage after chemical strengthening is evaluated by the amount of warpage displacement obtained by the following formula in the experiment under the same conditions except that the surface treatment is performed with a fluorine-containing fluid.

Warpage displacement = ΔX−ΔY
ΔX: amount of warpage change due to chemical strengthening of untreated glass plate ΔY: amount of warpage change due to chemical strengthening of treated glass plate Here, the amount of warpage change is the amount of warpage of the glass plate after chemical strengthening, and the glass plate before chemical strengthening The value obtained by subtracting the amount of warpage. The amount of change in warping is ΔX> 0. If ΔY warps in the same direction as ΔX, ΔY> 0, and if it warps in the opposite direction to ΔX, ΔY <0.

The amount of warpage change due to chemical strengthening of untreated glass sheets varies greatly depending on various conditions. That the amount of warp displacement is larger than a predetermined value means that the warp can be controlled regardless of the above-mentioned variation. Therefore, a glass plate having a warp displacement amount of a predetermined value, specifically, 10 μm or more can reduce the warp problem.

The CS (surface compressive stress) and DOL (compressive stress layer depth) of the glass plate can be measured with a surface stress meter. The surface compressive stress of the chemically strengthened glass is preferably 600 MPa or more, and the depth of the compressive stress layer is preferably 15 μm or more. By setting the surface compressive stress and the depth of the compressive stress layer of the chemically tempered glass within the above ranges, excellent strength and scratch resistance can be obtained.

4). Flat panel display device Hereinafter, after chemically strengthening the glass plate of the present invention, an example in which the chemically strengthened glass is used as a cover glass of the flat panel display device will be described. FIG. 3 is a cross-sectional view of a display device in which a cover glass is disposed. In the following description, front, rear, left and right are based on the direction of the arrow in the figure.

As shown in FIG. 3, the display device 40 includes a display panel 45 provided in the housing 15 and a cover glass 30 that covers the entire surface of the display panel 45 and surrounds the front of the housing 15.

The cover glass 30 is installed mainly for the purpose of improving the aesthetics and strength of the display device 40, preventing impact damage, and the like, and the overall shape is formed from a single plate-like glass having a substantially planar shape. As shown in FIG. 3, the cover glass 30 may be installed so as to be separated from the display side (front side) of the display panel 45 (having an air layer), and has a translucent adhesive film (FIG. (Not shown) may be attached to the display side of the display panel 45.

A functional film 41 is provided on the front surface of the cover glass 30 that emits light from the display panel 45, and a functional film 42 is provided on the rear surface on which the light from the display panel 45 is incident at a position corresponding to the display panel 45. ing. In addition, although the

functional films

41 and 42 are provided on both surfaces in FIG. 3, the

functional films

41 and 42 are not limited to this and may be provided on the front surface or the back surface, or may be omitted.

The

functional films

41 and 42 have functions such as anti-reflection of ambient light, prevention of impact breakage, electromagnetic wave shielding, near-infrared shielding, color tone correction, and / or scratch resistance improvement, and thickness and shape are used for applications. It is selected as appropriate. The

functional films

41 and 42 are formed, for example, by attaching a resin film to the cover glass 30. Or you may form by thin film formation methods, such as a vapor deposition method, a sputtering method, or CVD method.

Reference numeral 44 denotes a black layer, which is, for example, a coating formed by applying ink containing pigment particles to the cover glass 30, irradiating it with ultraviolet rays, or heating and baking it, and then cooling it. The display panel and the like cannot be seen from the outside, and the appearance is improved.

Thus, when the glass plate of the present invention is used as a cover glass for a display device, the surface roughness (arithmetic average roughness) Ra is preferably 2.5 nm or less, and more preferably 1.5 nm or less. . Thereby, it can prevent impairing the clearness of the display image of a display apparatus with a cover glass. The surface roughness Ra of the glass plate can be measured as follows based on JIS B0601 (2001). Using an AFM (Atomic Force Microscope), for example, Park Systems, XE-HDM as a measuring device, measure 3 locations at a scan size of 1 μm × 1 μm, and average the 3 locations. Ra value.

Examples of the present invention will be specifically described below, but the present invention is not limited to these.

(Composition of glass plate)
In this example, glass plates of glass materials A to C having the following composition were used.
(Glass A) In terms of mol%, SiO ₂ is 64.3%, Al ₂ O ₃ is 8.0%, Na ₂ O is 12.5%, K ₂ O is 4.0%, and MgO is 10.5. %, CaO 0.1%, SrO 0.1%, BaO 0.1% and ZrO ₂ 0.5% (glass transition temperature 604 ° C.)
(Glass B) Glass containing 68.0% of SiO ₂ , 10.0% of Al ₂ O ₃ , 14.0% of Na ₂ O and 8.0% of MgO in terms of mol% (glass transition temperature 662) ℃)
(Glass material C) In terms of mol%, SiO ₂ is 68.8%, Al ₂ O ₃ is 3.0%, Na ₂ O is 14.2%, CaO is 7.8%, MgO is 6.2%, and Glass containing 0.2% of K ₂ O (glass transition temperature 552 ° C.)
(Glass material D) In terms of mol%, SiO ₂ is 66.5%, Al ₂ O ₃ is 4.0%, Na ₂ O is 15.5%, MgO is 11.8%, and CaO is 2.1%. Glass (glass transition temperature 578 ° C)
(Glass material E) By mol%, SiO ₂ 66.9%, Al ₂ O ₃ 3.4%, Na ₂ O 15.4%, MgO 13.2% and CaO 1.1% Glass (glass transition temperature 580 ° C)

(Measurement of warpage)
Before chemical strengthening, measure the amount of warpage with a Surfcom surface roughness / contour shape measuring machine (manufactured by Tokyo Seimitsu Co., Ltd.), then chemically strengthen each glass and measure the amount of warpage after chemical strengthening in the same way. The amount of warpage displacement was calculated based on

(Surface layer fluorine ratio, ΔF / ΔH ₂ O, x)
Using the above-described secondary ion mass spectrometry, the thickness direction distributions of fluorine concentration and H ₂ O concentration were measured for the glass plates before chemical strengthening of the examples and comparative examples. Based on the measurement result, the above-mentioned surface layer fluorine ratio, ΔF / ΔH ₂ O, x was obtained.

(With or without recess)
The HF-treated surface of the glass was observed with an SEM. If one or more recesses were observed in the observation field (magnification of 50,000 to 200,000 times), it was determined that there was a recess.

(CS and DOL)
CS and DOL were measured using a surface stress meter (FSM-6000LE) manufactured by Orihara Seisakusho.

[Example 1]
HF treatment was performed in a float bath in which the glass ribbon of glass material A (Examples 1-1 to 1-16, Comparative Example 1-1) flows. The obtained glass was measured by the above-described procedure, and the surface layer fluorine ratio, ΔF / ΔH ₂ O, x was calculated.

The obtained glass with a thickness of 0.7 mm was cut into three pieces of 100 mm square, the warpage of two diagonal lines corresponding to the 90 mm square portion of the substrate was measured, and the average value was taken as the amount of warpage before strengthening. . Thereafter, the glass was immersed in KNO ₃ molten salt heated to 450 ° C. for 2 hours for chemical strengthening. Next, the warpage of two diagonal lines corresponding to the 90 mm square portion of the substrate was measured, and the warpage displacement was calculated by taking the average value as the warpage amount after strengthening.

Incidentally, Comparative Example 1-1 is a reference not subjected to HF treatment.

The results are shown in Tables 1-2. The total contact amount (mol / cm ² ) of HF in Table 1 is determined by the following equation. The processing time in the formula is the time during which the HF gas is in contact with the surface of the glass ribbon.
[HF total contact amount (mol / cm ² )] = [HF gas concentration (volume%)] / 100 × [gas flow rate (mol / s / cm ² )] × [treatment time (s)] (b)
FIG. 9 is a graph in which ΔF / ΔH ₂ O is plotted on the horizontal axis and the amount of warp displacement (μm) is plotted on the vertical axis.

As shown in Tables 1 and 2, Examples 1-1 to 1-16 in which the surface layer fluorine ratio is 0.1 or more and less than 0.5 and F _0-3 is greater than 0.02, It was found that the warpage was effectively improved. In addition, in Examples 1-1 to 1-16 and Comparative Example 1-1, no occurrence of a recess was observed.

As shown in FIG. 9, ΔF / ΔH ₂ O and the warpage displacement amount showed a correlation (y = 26.03x). In order to improve the warp after chemical strengthening, the warp displacement is preferably 10 μm or more. From the graph shown in FIG. 9, by setting ΔF / ΔH ₂ O to 0.38 or more, It was found that the warpage can be effectively improved. As shown in Tables 1 and 2, it was found that in Examples 1-1 to 1-16 in which ΔF / ΔH ₂ O was 0.38 or more, warpage after chemical strengthening was effectively improved. Further, as shown in Tables 1 and 2, in Examples 1-1 to 1-16 in which x (μm) was 5 or more, the warpage after chemical strengthening was effectively improved.

[Example 2]
Glass material B (Examples 2-1 to 2-6, Comparative Example 2-1) was prepared in the same manner as in Example 1 except that the glass material A was changed to the glass material B and the chemical strengthening treatment time was 1.5 hours. The HF treatment was performed in a float bath in which the glass ribbon of (2-2) flows. The obtained glass was measured in the same procedure as in Example 1, and the surface layer fluorine ratio, ΔF / ΔH ₂ O, x, the warpage amount before strengthening, the warpage amount after strengthening, the warpage displacement amount, and the like were calculated. In Example 2, the temperature of the glass ribbon during HF treatment is set higher than in Example 1.

Comparative Examples 2-1 and 2-2 are references not subjected to HF processing.

The results are shown in Tables 3-4.

As shown in Tables 3 to 4, Examples 2-1 to 2-6 in which the surface layer fluorine ratio is 0.1 or more and less than 0.5, and F _0-3 is larger than 0.02, It was found that the warpage was effectively improved. Note that no recess was observed in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-2.

Further, it was found that by setting ΔF / ΔH ₂ O to 0.38 or more, the warpage displacement amount is 10 μm or more, and the warpage after chemical strengthening can be effectively improved. In addition, it was found that in Examples 2-1 to 2-6 in which ΔF / ΔH ₂ O was 0.38 or more, the warpage after chemical strengthening was effectively improved. Further, in Examples 2-1 to 2-6 in which x (μm) is 5 or more, the warpage after chemical strengthening was effectively improved.

[Example 3]
The glass material A (Examples 3-1 to 3-4, HF treatment was carried out in a float bath in which the glass ribbon of Comparative Example 3-1) flows. The obtained glass was measured in the same procedure as in Example 1, and the surface layer fluorine ratio, ΔF / ΔH ₂ O, x, the warpage amount before strengthening, the warpage amount after strengthening, the warpage displacement amount, and the like were calculated.

Comparative Example 3-1 is a reference not subjected to HF processing.

Results are shown in Tables 5-6.

As shown in Tables 5 to 6, Examples 3-1 to 3-4 in which the surface layer fluorine ratio is 0.1 or more and less than 0.5 and F _0-3 is greater than 0.02 It was found that the warpage was effectively improved. In addition, in Examples 3-1 to 3-4 and Comparative Example 3-1, no occurrence of a recess was observed.

Further, it was found that by setting ΔF / ΔH ₂ O to 0.38 or more, the warpage displacement amount is 10 μm or more, and the warpage after chemical strengthening can be effectively improved. In addition, it was found that in Examples 3-1 to 3-4 in which ΔF / ΔH ₂ O was 0.38 or more, warpage after chemical strengthening was effectively improved. Further, in Examples 3-1 to 3-4 in which x (μm) is 5 or more, the warpage after chemical strengthening was effectively improved.

[Example 4]
The raw material was prepared so as to have the glass composition of glass material D (Example 4-1 and Comparative Example 4-1), melted using a crucible, processed into a size of 50 mm × 50 mm and a thickness of 0.7 mm, and a glass plate Was made. As shown in the schematic diagram of FIG. 12, the glass plate was placed in an electric furnace and the atmosphere gas was replaced with an atmosphere of 90% N ₂ and 10% H ₂ , and then the glass plate was heated to 880 ° C. The HF treatment was performed under the conditions shown below. The glass plate thus obtained was chemically strengthened by immersing it in KNO ₃ molten salt heated to 420 ° C. for 2.5 hours.
Except that the glass material D was changed to the glass material E (Example 4-2, Comparative Example 4-2), a glass plate was prepared, HF treatment, and chemical strengthening treatment were performed in the same manner as in Example 4-1.
The obtained glass plate was measured in the same procedure as in Example 1, and the results of calculating the surface layer fluorine ratio, x, the amount of warp before strengthening, the amount of warp after strengthening, the amount of warp displacement, etc. are shown in Table 7.
Comparative examples 4-1 and 4-2 are references not subjected to HF processing.

As shown in Table 7, in Examples 4-1 to 4-2 in which the surface layer fluorine ratio is 0.1 or more and less than 0.5 and F0-3 is greater than 0.02, warping after chemical strengthening is effective. It was found that it was improved. In addition, in Examples 4-1 to 4-2 and Comparative Examples 4-1 to 4-2, no recess was observed. Further, in Examples 4-1 to 4-2 in which x (μm) was 5 or more, the warpage after chemical strengthening was effectively improved.

Although the 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 invention.
In addition, this application is a Japanese patent application filed on September 25, 2013 (Japanese Patent Application No. 2013-198477) and a Japanese patent application filed on December 13, 2013 (Japanese Patent Application No. 2013-258466). Which is incorporated by reference in its entirety.

DESCRIPTION OF SYMBOLS 1 Central slit 2 Outer slit 4 Flow path 5 Exhaust slit 15 Housing | casing 20 Glass plate 30 Cover glass 40

Display apparatus

41, 42 Functional film 45 Display panel 101 Glass ribbon 102 Beam 103 Radiation gate 110 Glass ribbon width direction 111,112, 113

Gas system

114, 115 Partition 116 Gas blow hole

Claims

A glass plate in which the fluorine concentration on one surface facing the thickness direction is larger than the fluorine concentration on the other surface, and the surface layer fluorine ratio represented by the following formula (I) is 0.1 or more and less than 0.5, And a glass plate in which F 0-3 represented by the following formula (II) is larger than 0.02.
Surface layer fluorine ratio = F 0-3 / F 0-30 (I)
In the formula (I), F 0-3 is determined by the following formula (II).
F 0-3 = [Average fluorine concentration (mol%) by secondary ion mass spectrometry (SIMS) at a depth of 0 to 3 μm on a surface with a large fluorine concentration] × 3 (II)
In the formula (I), F 0-30 is determined by the following formula (III).
F 0-30 = [Average fluorine concentration (mol%) by SIMS at a depth of 0 to 30 μm on a surface with a large fluorine concentration] × 30 (III)
The glass plate according to claim 1, wherein the surface layer fluorine ratio is 0.15 or more.
The glass plate according to claim 1 or 2, wherein the surface layer fluorine ratio is 0.15 or more and 0.4 or less.
The glass plate according to claim 3, wherein the surface layer fluorine ratio is 0.3 or less.
The glass plate according to any one of claims 1 to 4, wherein the glass plate satisfies the following formula (1). Here, the fluorine concentration is an average fluorine concentration (mol%) by SIMS having a depth of 1 to 24 μm.
0.38 ≦ ΔF / ΔH 2 O (1)
In the formula (1), ΔF is an average fluorine concentration (mol%) by SIMS at a depth of 1 to 24 μm on a surface with a low fluorine concentration from an average fluorine concentration (mol%) by SIMS at a depth of 1 to 24 μm on a surface with a high fluorine concentration. %).
In formula (1), ΔH 2 O is an average of SIMS having a depth of 1 to 24 μm on a surface having a high fluorine concentration from an average H 2 O concentration (mol%) of SIMS having a depth of 1 to 24 μm on a surface having a low fluorine concentration. The absolute value of the value obtained by subtracting the H 2 O concentration (mol%).
The glass plate according to any one of claims 1 to 5, wherein the glass plate satisfies the following formula (2). Here, the fluorine concentration is an average fluorine concentration (mol%) by SIMS having a depth of 1 to 24 μm.
5 ≦ x (2)
In the formula (2), x is the maximum depth (μm) in which the slope at an arbitrary depth x i (μm) satisfies the following formula (3) in the fluorine concentration profile by SIMS.
[F (x i +0.1) −F (x i )] / 0.1 = −0.015 (3)
In formula (3), F (x i ) represents the fluorine concentration (mol%) by SIMS at the depth x i (μm).
The glass plate according to any one of claims 1 to 6, which is a glass plate produced by a float process.
The glass plate according to any one of claims 1 to 7, which has a thickness of 1.5 mm or less.
The glass plate according to any one of claims 1 to 8, wherein the thickness is 0.8 mm or less.
The glass plate according to any one of claims 1 to 9, wherein the surface roughness Ra is 2.5 nm or less.
The glass plate according to any one of claims 1 to 10, wherein a concave portion having a diameter of 10 nm or more does not exist on the surface having a larger fluorine concentration, or the concave portions exist at a density of 6 pieces / μm 2 or less.
A glass plate obtained by chemically strengthening the glass plate according to any one of claims 1 to 11.
A flat panel display device comprising a cover glass, wherein the cover glass is the glass plate according to claim 12.