WO2017026450A1 - Glass having duv resistance - Google Patents

Abstract

The present invention pertains to glass that contains Ｆｅ_２Ｏ_３：０．００１～０．０２２％、 ＴｉＯ_２：０．０１１～０．８％ and/or ＺｒＯ_２：０．７～４．０％, and Ａｌ_２Ｏ_３：７．５～１８％, does not contain Ａｓ_２Ｏ_３, and has transmittance at a wavelength of 380-780 nm after being subjected to treatment by condition 1 of 80% or higher. (Condition 1) The glass is heat treated for one hour at (Tg + 40)°C, slowly cooled to room temperature at 0.5°C/min, and then irradiated for 10 minutes by a low-pressure mercury lamp having a wavelength of 254 nm and illuminance of 8 mW/cm².

Description

DUV resistant glass

The present invention relates to a glass having DUV (Deep UV) resistance, and more particularly to a glass having DUV resistance and excellent chemical strengthening properties.

In recent years, high-strength glass has been demanded for displays such as mobile phones or personal digital assistants (PDAs). For this reason, the glass is strengthened by chemical strengthening treatment (chemically strengthened glass). Conventionally, soda lime glass has been widely used as a glass plate for display, but its chemical strengthening properties are insufficient, and its strength is low even after chemical strengthening. Therefore, aluminosilicate glass has been developed as a glass for chemical strengthening that has high chemical strengthening characteristics and can achieve high strength.

Chemically tempered glass is useful for display applications because of its high strength, but it is required to be highly transmissive in addition to high strength in order to ensure the visibility of the display screen. Therefore, a highly permeable chemically strengthened glass in which the iron content that contributes to coloration is reduced has been studied.

As one of the factors that lower the transmittance of glass, so-called solarization is known in which the valence state of a polyvalent cation such as a transition metal ion or rare earth ion changes due to the influence of ultraviolet rays or the like, and the color of the glass changes.
In Patent Document 1, in order to increase the resistance to solarization of the glass, colored glass containing TiO ₂ is disclosed.

International Publication No. 2013/021975

High-strength glass that has been chemically strengthened (chemically strengthened glass) is subjected to various pretreatments when used for a display or the like. One example is UV ozone cleaning treatment by ultraviolet irradiation in a wavelength region called DUV (Deep UV) using a low-pressure mercury lamp, and there are cases where organic substances on the glass surface are removed or surface modification is performed.

DUV has a shorter wavelength than UV in solarization caused by sunlight.
According to the study by the present inventors, it has been found that the transmittance in a specific wavelength region of the glass is lowered by the irradiation of the DUV. As a result, when the DUV is irradiated, the transparency of the glass is impaired, and the color of the glass deteriorates depending on the region where the transmittance is reduced.

Accordingly, an object of the present invention is to provide a glass that does not lower the transmittance even when irradiated with UV on the short wavelength side such as a low-pressure mercury lamp.
In the present specification, “DUV resistance” refers to a change in transmittance before and after irradiation with a short wavelength UV of 185 nm and 254 nm using a low-pressure mercury lamp. “Solarization resistance” is intended for the transmittance change before and after UV irradiation with a main wavelength of 365 nm using a high-pressure mercury lamp. Further, the short wavelength side UV and the long wavelength side UV may be collectively referred to simply as “UV”.

As a result of intensive studies, the present inventors have found that, by adopting a specific glass composition, glass can be obtained without lowering the transmittance even when UV on the short wavelength side is irradiated. The invention has been completed.

That is, the present invention relates to the following <1> to <10>.
<1> Fe ₂ O ₃ : 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8% and ZrO ₂ : 0.7 to 4.0% in terms of mole percentage based on oxide The transmittance at a wavelength of 380 to 780 nm after the treatment under the following condition 1 is 80, including at least one of the following: Al ₂ O ₃ : 7.5 to 18%, not including As ₂ O ₃ % Glass or more.
(Condition 1) The glass was heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then irradiated with a low-pressure mercury lamp having a wavelength of 254 nm and an illuminance of 8 mW / cm ² for 10 minutes.
<2> The glass according to <1>, wherein the absorption coefficient α at a wavelength of 380 to 780 nm after the treatment under the condition 1 is 1.35 × 10 ⁻² cm ⁻¹ or less.
<3> The glass according to <1> or <2>, wherein the color tone b ^* in the chromaticity coordinates of the L ^* a ^* b ^* color system after the treatment under the condition 1 is 2.0 or less.
<4> Oxide-based molar percentage display, containing 50 to 80% SiO ₂ and containing at least one of Li ₂ O, Na ₂ O and K ₂ O, Li ₂ O, Na ₂ The glass according to any one of <1> to <3>, wherein the total Li ₂ O + Na ₂ O + K ₂ O content of O and K ₂ O is 5 to 25%.
<5> The glass according to any one of <1> to <4>, which contains substantially no coloring component other than TiO ₂ and Fe ₂ O ₃ .
<6> The glass according to any one of <1> to <5>, which contains SnO ₂ in an amount of 0.001 to 1% in terms of a molar percentage based on an oxide.
<7> SiO ₂ is contained, Li ₂ O is not contained, and the content expressed in terms of mole percentage based on oxides of Na ₂ O, K ₂ O, Al ₂ O ₃ and SiO ₂ is [2 × The glass according to any one of <1> to <6>, wherein a relationship of (Na ₂ O + K ₂ O—Al ₂ O ₃ ) / SiO ₂ ] ≦ 0.5 is satisfied.
<8> Oxide-based molar percentage display, SiO ₂ 60 to 70%, Al ₂ O ₃ 7.5 to 18%, Li ₂ O, Na ₂ O and K ₂ O at least one total 5 to 25%, MgO 0 to 15%, CaO 0 to 5%, Fe ₂ O ₃ 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8%, and ZrO ₂ : 0 7 to 4.0%, and the total content of other components is 3% or less, Li ₂ O, Na ₂ O, K ₂ O, Al ₂ O ₃ and SiO ₂ <1> to << in which the content expressed in terms of mole percentage on the basis of oxide satisfies the relationship of [2 × (Li ₂ O + Na ₂ O + K ₂ O—Al ₂ O ₃ ) / SiO ₂ ] ≦ 0.5 The glass according to any one of 7>.
<9> Oxide-based molar percentage display, SiO ₂ 63-66%, Al ₂ O ₃ 9-12%, Na ₂ O 14-17%, K ₂ O 0-1%, MgO 7 to 9%, CaO 0 to 1%, Fe ₂ O ₃ 0.001 to 0.022%, TiO ₂ 0.011 to 0.8%, and other components in total 3 % Or less of the glass according to any one of <1> to <7>.
<10> A chemically strengthened glass obtained by chemically strengthening the glass according to any one of <1> to <9>.

According to the present invention, it is possible to obtain a glass having a high transmittance before UV irradiation and which does not decrease the transmittance even when UV on the short wavelength side is irradiated. It is very useful as a chemically strengthened glass used for display applications.

FIG. 1 is a graph showing a change in transmittance spectrum when a glass of Test Example 1 (Comparative Example) is irradiated with a low-pressure mercury lamp. FIG. 2 is a graph showing the ESR spectrum change when the glass of Test Example 1 (Comparative Example) is irradiated with a low-pressure mercury lamp. FIG. 3 is a fluorescence spectrum of the glass of Test Example 6 (Comparative Example). FIG. 4 is a transmittance spectrum before and after the glass of Test Example 1 (Comparative Example) is irradiated with a low-pressure mercury lamp. FIG. 5 is a transmittance spectrum before and after the glass of Test Example 5 (Example) was irradiated with a low-pressure mercury lamp. FIG. 6 is a graph showing the change in transmittance at a wavelength of 380 nm before and after the glass is irradiated with a low-pressure mercury lamp for each TiO ₂ content in the glass. FIG. 7 is a graph showing the relationship between the TiO ₂ content in the glass and the DOL after the chemical strengthening treatment.

Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention. In this specification, when “%” is simply described, it means “mol%”, and “˜” means that it is not less than the lower limit value and not more than the upper limit value.

<Glass>
The glass according to the present invention is expressed in terms of mole percentage based on oxide, Fe ₂ O ₃ : 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8%, and ZrO ₂ : 0.7 to At least one of 4.0% and Al ₂ O ₃ : 7.5 to 18%, no As ₂ O ₃ , and a wavelength of 380 to 780 nm after performing the treatment under the following condition 1 The transmittance is 80% or more. That is, the DUV resistance is excellent.
(Condition 1) The glass was heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then irradiated with a low-pressure mercury lamp having a wavelength of 254 nm and an illuminance of 8 mW / cm ² for 10 minutes.
The glass composition can be measured by the fluorescent X-ray method, and more precisely by the wet analysis method. The glass composition will be described later.

(DUV resistance)
In this specification, the DUV resistance means that UV (DUV) with a wavelength of 100 to 280 nm is irradiated, that is, a low-pressure mercury lamp with main wavelengths of 185 nm and 254 nm, an Xe gas excimer lamp with a main wavelength of 172 nm, and an ArF excimer lamp with a main wavelength of 193 nm. This means that when a KrF excimer lamp having a main wavelength of 248 nm is irradiated, a decrease in transmittance at a wavelength of 380 to 780 nm is suppressed.
This UV irradiation on the short wavelength side is generally used for UV cleaning treatment, surface modification, UV sterilization treatment and the like of the substrate.

The DUV irradiation is performed within a range of irradiation time of 1 to 20000 seconds with an illuminance at a wavelength of 254 nm of 0.1 to 1000 mW / cm ² on the surface of the glass irradiated with light. From the aspect of reducing the processing cost, it is preferable that the irradiation time is 1 to 100 mW / cm ² and the irradiation time is 1200 seconds or less. The exposure preferably be carried out at the 10 ~ 10000mJ / cm ² condition, more preferably of 50 ~ 5000mJ / cm ² conditions.
In the present invention, in order to more accurately evaluate the DUV resistance of glass, physical properties (transmittance, absorption coefficient, DUV and UV-induced absorption, etc.) after the treatment under the following condition 1 can be evaluated. preferable.
(Condition 1) The glass was heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then irradiated with a low-pressure mercury lamp having a wavelength of 254 nm and an illuminance of 8 mW / cm ² for 10 minutes.
In addition, the illumination intensity in this specification means the illumination intensity right above a glass surface instead of the illumination intensity right under a lamp.

By performing the heat treatment under the above condition 1, the effect of the previous DUV irradiation on the glass is canceled, and the transmittance and color return to the original glass state (initial state). Therefore, the physical properties of the glass after DUV irradiation can be evaluated without variation by irradiating the short wavelength side UV under the above condition 1 after the heat treatment.

Note that the DUV resistance in this specification does not include suppression of a decrease in transmittance when a light source having a high optical power density, such as an ArF excimer laser having a main wavelength of 193 nm or a KrF excimer laser having a main wavelength of 248 nm, is used.

In the glass according to the present invention, as DUV resistance, the transmittance in the wavelength region of 380 to 780 nm before UV irradiation on the short wavelength side is T0, and the transmittance in the wavelength region of 380 to 780 nm after irradiation is T1. The DUV-induced absorption Δα at each wavelength represented by the following formula is preferably 0.095 or less, and more preferably 0.085 or less.
Δα = -ln (T1 / T0)

(Solarization resistance)
The resistance to solarization means that a decrease in transmittance at a wavelength of 380 to 780 nm is suppressed when irradiated with UV light having a wavelength of 315 to 400 nm, that is, when irradiated with a high-pressure mercury lamp having a main wavelength of 365 nm or sunlight. means.
This UV irradiation on the long wavelength side is generally used for lamination and the like with a substrate using a UV curable resin.

The UV irradiation on the long wavelength side is carried out within a range of irradiation time of 1 to 20000 seconds with an illuminance at a wavelength of 365 nm of 0.1 to 1000 mW / cm ² on the surface of the glass irradiated with light. . From the aspect of reducing the processing cost, it is preferable that the irradiation time is 1 to 100 mW / cm ² and the irradiation time is 1200 seconds or less. The exposure amount is preferably 10 to 10,000 mJ / cm ² .

In the glass according to the present invention, as solarization resistance, the transmittance in the wavelength region of 380 to 780 nm before UV irradiation on the long wavelength side is T0 ′, and the transmittance in the wavelength region of 380 to 780 nm after irradiation is T1 ′. The UV-induced absorption Δα ′ at each wavelength represented by the following formula is preferably 0.095 or less, and more preferably 0.085 or less.
Δα ′ = − ln (T1 ′ / T0 ′)

(Transparency)
The glass according to the present invention has a transmittance of 90% or more at a wavelength of 380 to 780 nm before irradiating UV to a glass having a thickness of 1 mm, preferably 90.5% or more, more preferably 91% or more, Preferably it is 91.5% or more. Further, the transmittance at a wavelength of 380 to 780 nm after irradiating a glass having a thickness of 1 mm with short wavelength side UV and / or long wavelength side UV is 80% or more, preferably 81% or more, more preferably 82% or more, more preferably 83% or more, and most preferably 84% or more.
However, the degree of change in transmittance after UV irradiation varies depending on UV irradiation conditions, glass composition, thickness, manufacturing method, and the like.
In the glass according to the present invention, the wavelength at which the transmittance is less than 1% is preferably 280 nm or less before and after irradiating the glass having a thickness of 1 mm with UV. If the wavelength exceeds 280 nm, sufficient transmittance cannot be obtained at wavelengths of 380 to 780 nm, and the color of the transmitted color of the glass may be deteriorated, such as coloring yellow.

(Absorption coefficient)
The glass according to the present invention has an absorption coefficient α of 2.35 × 10 ⁻³ cm ⁻¹ or less, preferably 1.80 × 10 ⁻³ cm ⁻¹ or less, at a wavelength of 380 to 780 nm before UV irradiation. More preferably, it is 1.25 × 10 ⁻³ cm ⁻¹ or less, and further preferably 7.00 × 10 ⁻⁴ cm ⁻¹ or less. Further, the absorption coefficient α at a wavelength of 380 to 780 nm after irradiation with UV on the short wavelength side is preferably 1.35 × 10 ⁻² cm ⁻¹ or less, more preferably 1.25 × 10 ⁻² cm ⁻¹ or less, More preferably, it is 1.12 × 10 ⁻² cm ⁻¹ or less, even more preferably 1.00 × 10 ⁻² cm ⁻¹ or less, and most preferably 8.82 × 10 ⁻³ cm ⁻¹ or less.

The absorption coefficient α of the glass can be obtained according to the following formula, assuming that the absorption at a wavelength of 780 nm is zero. Here, the reason why the absorption at a wavelength of 780 nm is regarded as zero and used as a reference is to subtract the influence of the reflection of the glass.
α = 2.303 × log (T ₇₈₀ / Ti) / d
Ti: Transmittance of measurement wavelength (%)
_T780 : Transmittance (%) at a wavelength of 780 nm
d: Glass thickness (cm)

(Transparent color)
The L ^* a ^* b ^* color system transmission color of the glass before and after being irradiated with UV on the short wavelength side is calculated from the tristimulus values X, Y, Z of the object based on JIS Z8722: 2009 from the transmittance measurement data. Then, it can be obtained by converting to the L ^* a ^* b ^* color system (D65 light source, 2-degree visual field) by the following formula.
L ^* = 116 × (Y / Yn) ^1/3 −16
a ^* = 500 × [(X / Xn) ¹ /3-(Y / Yn) ^1/3 ]
b ^* = 200 × [(Y / Yn) ¹ /3-(Z / Zn) ^1/3 ]
However, Xn = 95.02, Yn = 100, Zn = 108.82

The color tone b ^* in the chromaticity coordinates after irradiation with UV on the short wavelength side is preferably 2.0 or less, more preferably 1.8 or less, still more preferably 1.6 or less, and particularly preferably 1.0 or less. preferable.

(Chromaticity change)
The chromaticity change means a difference (change) in chromaticity of the glass before and after irradiating UV on the short wavelength side or long wavelength side, and can be evaluated by ΔE obtained by the following formula. If the change in chromaticity (value of ΔE) is large, it means that the color of the glass is poor. Therefore, it is preferable that the change in chromaticity is small.
Specifically, the chromaticity difference (chromaticity change) ΔE between before and after irradiation with UV on the short wavelength side is preferably 2 or less, more preferably 1.8 or less, and 1. 7 or less is more preferable, and 1.5 or less is most preferable.

In the above formula, L ₀ ^* , a ₀ ^* , b ₀ ^* are the values of the respective color tones in the chromaticity coordinates of the L ^* a ^* b ^* color system of the glass before UV irradiation, and L ^* , a ^{* And} b ^* are the values of the respective color tones in the chromaticity coordinates of the L ^* a ^* b ^* color system of the glass after UV irradiation.
Further, the values of each color tone can be converted from the measured data of transmittance based on JIS Z8722: 2009 based on the tristimulus values X, Y, and Z of the object, and converted from these values by the above-described formula.

(Glass composition)
The glass according to the present invention is expressed in terms of mole percentage based on oxide, Fe ₂ O ₃ : 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8%, and ZrO ₂ : 0.7 to It contains at least one of 4.0%.

By containing Fe ₂ O ₃ , the DUV resistance is increased, but the color of the glass is deteriorated. In the present invention, the content of Fe ₂ O ₃ is 0.001 to 0 by including at least one of TiO ₂ : 0.011 to 0.8% and ZrO ₂ : 0.7 to 4.0%. Even when the content is as low as 0.022%, the change in chromaticity can be reduced while maintaining high DUV resistance.
Also although TiO ₂ and Fe ₂ O ₃ is a component which can be a coloring component, it is possible to content can be almost neglected coloring in the above range to obtain a high transmittance glass.

TiO ₂ is more preferably 0.015% or more, more preferably 0.02% or more, particularly preferably 0.03% or more, and most preferably 0.05% or more, because more excellent DUV resistance can be obtained. On the other hand, 0.7% or less is more preferable, 0.6% or less is more preferable, 0.5% or less is particularly preferable, and 0.4% is more preferable in that the change in chromaticity can be further reduced and the chemical strengthening characteristics are not deteriorated. The following are most preferred.

ZrO ₂ is a component that gives excellent DUV resistance, at the same time, improves chemical durability, increases the surface compressive stress (CS) during chemical strengthening, and improves Vickers hardness after chemical strengthening. is there. When TiO ₂ is not added, the content of ZrO ₂ is preferably 0.7% or more, more preferably 0.9% or more, further preferably 1.2% or more, and most preferably 1.5% or more. On the other hand, the amount added is preferably 4.0% or less from the viewpoint of suppressing devitrification during the production of glass and preventing a reduction in the depth of compression stress layer (DOL; Depth of Layer) during chemical strengthening. % Or less is more preferable, 3% or less is more preferable, and 2.5% or less is most preferable.

TiO ₂ and ZrO ₂ are both components that improve DUV resistance, but TiO ₂ has a greater effect of improving DUV resistance than ZrO ₂ . More preferably, the glass according to the present invention contains only TiO ₂ or both TiO ₂ and ZrO ₂ .

Fe ₂ O ₃ is preferably 0.001% or more. If it is less than 0.001%, sufficient DUV resistance may not be obtained. Further, in manufacturing the glass, the amount of impurities of Fe ₂ O ₃ components other than Fe ₂ O ₃ is not necessary to use very little material, there is a possibility that the manufacturing cost is increased. Fe ₂ O ₃ is more preferably 0.0015% or more, further preferably 0.002% or more, and particularly preferably 0.0025% or more. Moreover, from the point which can reduce a chromaticity change, 0.022% or less is preferable, 0.015% or less is more preferable, 0.008% or less is further more preferable, 0.005% or less is especially preferable.

By setting Fe ₂ O ₃ and TiO ₂ in the above ranges, a highly transparent glass having excellent DUV resistance and resistance to solarization and little change in chromaticity can be obtained.

Regarding DUV resistance, SnO ₂ , MoO ₃ , Ta ₂ O ₅ , and Nb ₂ O ₅ can be used together with TiO ₂ and / or ZrO ₂ or in place of TiO ₂ and / or ZrO _2. .
When using SnO ₂ , MoO ₃ , Ta ₂ O ₅ , and Nb ₂ O ₅ , it is necessary to set optimum conditions separately in order to achieve compatibility with other characteristics such as solarization resistance and permeability. The total amount of SnO ₂ , MoO ₃ , Ta ₂ O ₅ and Nb ₂ O ₅ is preferably 0.001 to 1%, and 0.01 to 0.5% in terms of mol% based on oxide. Is more preferable.

All of these components have an absorption coefficient of 1 cm ⁻¹ or more at a wavelength of 220 nm (5.6 eV). That is, when irradiated with UV on the short wavelength side, these components absorb energy in the vicinity of a wavelength of 220 nm (5.6 eV) and suppress absorption by the glass structure itself, so that a glass structure that causes a decrease in transmittance. It is considered that the generation of defects is suppressed and the DUV resistance is improved.

The following can be considered about the details of the transmittance reduction by DUV irradiation.
FIG. 1 shows a change in transmission spectrum when a glass containing no TiO ₂ is polished to a plate thickness of 0.3 mm and then irradiated with a low-pressure mercury lamp (DUV). It can be seen that as the DUV irradiation time increases, the transmittance near the wavelength of 220 nm improves, while the transmittance near the wavelength of 400 to 500 nm decreases.
FIG. 2 shows evaluation of electron spin resonance (ESR) for the same glass as that evaluated in FIG. A peak that increases with an increase in the irradiation time of the low-pressure mercury lamp is presumed to be NBOHC (Non Bridging Oxygen Hole Center), which is a kind of glass structural defect. The ratio of the increase in peak intensity with respect to the irradiation time in FIG. 2 and the ratio of the decrease in transmittance with respect to the irradiation time in FIG. 1 correspond to about 1: 1. Therefore, the cause of the decrease in the transmittance in the visible region is NBOHC. It is believed that there is.

FIG. 3 shows a fluorescence spectrum when the glass of the present invention containing 1 mol% of TiO ₂ is excited at a wavelength of 220 nm and an excitation spectrum when monitored at an emission wavelength of 470 nm. TiO ₂ present in the form of Ti ⁴⁺ ions in the glass absorbs energy corresponding to the wavelength of 220 nm instead of the glass structure, and consumes energy absorbed by light emission (radiation transition) and thermal deactivation (non-radiation transition). Therefore, it is considered that the generation of NBOHC is suppressed. As can be seen from FIG. 3, since the glass of the present invention containing TiO ₂ is not excited at a wavelength around 365 nm and does not have absorption, it has high solarization resistance against high pressure mercury lamps and sunlight. Expected to be.

The glass according to the present invention contains 7.5 to 18% of Al ₂ O ₃ . The glass according to the present invention is, for example, an aluminosilicate glass. An aluminosilicate glass containing an alkali is suitable as a glass for chemical strengthening. The glass according to the present invention is preferably a chemically strengthened glass.

Al ₂ O ₃ has an effect of improving ion exchange performance in chemical strengthening, and in particular, has a large effect of improving a surface compressive stress (CS). It is also known as a component that improves the weather resistance of glass.

The Al ₂ O ₃ content is 7.5% or more, preferably 8% or more, more preferably 8.5% or more, further preferably 9% or more, and most preferably 9.5% or more. On the other hand, the upper limit is 18% or less, preferably 17.5% or less, more preferably 16% or less, further preferably 14% or less, and most preferably 12% or less.
When the content of Al ₂ O ₃ is 7.5% or more, a desired CS value is obtained by ion exchange, the weather resistance is improved, and the surface in contact with the tin fusion bath (bottom) in the float process The effect of suppressing the intrusion of tin from the surface) and making the glass difficult to warp during chemical strengthening, the effect of stability against changes in moisture content, and the effect of promoting alkali removal are obtained. On the other hand, when the content of Al ₂ O ₃ is 18% or less, since the devitrification temperature does not increase greatly even when the viscosity of the glass is high, it is advantageous in terms of melting and forming in a float facility, A decrease in acid resistance can be prevented.

SiO ₂ is known as a component that forms a network structure in the glass microstructure, and is a main component constituting the glass. Further, it is a component that reduces the occurrence of cracks when scratches (indentations) are made on the glass surface, or reduces the fracture rate when indentations are made after chemical strengthening. The content of SiO ₂ is preferably 50% or more, more preferably 55% or more, still more preferably 60% or more, and most preferably 63% or more. Further, the upper limit is preferably 80% or less, more preferably 75% or less, further preferably 73% or less, particularly preferably 70% or less, and most preferably 66% or less.
When the content of SiO ₂ is 50% or more, it is advantageous in terms of stability and weather resistance as glass. Moreover, an increase in thermal expansion can be suppressed by forming a network structure. On the other hand, when the content of SiO ₂ is 80% or less, it is advantageous in terms of solubility and moldability.

B ₂ O ₃ is a component that promotes melting of the glass raw material and improves the brittleness and weather resistance of the glass.
When B ₂ O ₃ is contained, the content is 1% or more, so that the fracture rate when scratches (indentations) are made after chemical strengthening can be reduced, or the meltability at high temperature is improved. To do. The content of B ₂ O ₃ is preferably 15% or less, more preferably 10% or less, and more preferably 7.5%, in order not to cause inconvenience such as generation of striae due to volatilization and furnace wall erosion. % Or less is particularly preferable. In the case where it is desired to further increase the homogeneity of the glass by suppressing the formation of striae or the like, 1% or less is preferable.

P ₂ O ₅ is a component that improves damage resistance without hindering ion exchange performance. In the case where P ₂ O ₅ is contained, a glass having a high crack extension starting load (CIL) can be obtained when the content is 2.5% or more. Further, the content of P ₂ O ₅ by 10% or less, it is possible to obtain an excellent glass in acid resistance. When it is desired to further increase the chemical durability of the glass, it is preferably 1% or less, and more preferably not contained.

Li ₂ O, Na ₂ O, and K ₂ O are all components that improve the meltability and moldability of the glass, and preferably contain at least one of them. The total Li ₂ O + Na ₂ O + K ₂ O content of Li ₂ O, Na ₂ O, and K ₂ O is preferably 5% or more, more preferably 8% or more, and even more preferably 12% or more. In order to increase the chemical durability of the glass, Li ₂ O + Na ₂ O + K ₂ O is preferably 25% or less, more preferably 22% or less, still more preferably 18% or less, and particularly preferably 15% or less.

Na ₂ O is an essential component for forming a surface compressive stress layer by ion exchange, and has the effect of deepening the DOL. Moreover, it is a component which lowers | hangs the melting temperature and devitrification temperature of glass, and improves the meltability and moldability of glass. Na ₂ O is a component that generates non-crosslinked oxygen, and the variation in chemical strengthening characteristics when the amount of moisture in the glass varies is reduced.
The Na ₂ O content is preferably 8% or more, more preferably 10% or more, still more preferably 11% or more, particularly preferably 12% or more, and most preferably 14% or more. The upper limit is preferably 22% or less, more preferably 19% or less, still more preferably 17% or less, and most preferably 15% or less.
When the content of Na ₂ O is 8% or more, a desired surface compressive stress layer can be formed by ion exchange, and fluctuations due to changes in moisture content can be suppressed. On the other hand, if the content of Na ₂ O is 22% or less, crack generation from the indentation can be avoided, sufficient weather resistance can be obtained, and the amount of intrusion of tin from the bottom surface can be suppressed during molding by the float method, It is possible to make the glass difficult to warp after the chemical strengthening treatment.

K ₂ O is an ingredient that increases the ion exchange rate, deepens the DOL, lowers the melting temperature of the glass, and increases non-crosslinked oxygen, so it may be contained in a range of 7% or less. If it is 7% or less, the DOL does not become too deep, sufficient CS is obtained, and the melting temperature of the glass can be lowered. Or avoid an increase in variation of surface compressive stress due NaNO ₃ concentration in the potassium nitrate molten salt. When it contains K ₂ O, it is preferably 5% or less, more preferably 2% or less, and particularly preferably 1% or less. On the other hand, since a small amount of K ₂ O has an effect of suppressing the amount of intrusion of tin from the bottom surface at the time of molding by the float process, it is preferably contained when molding by the float process. In this case, the content of K ₂ O is preferably 0.05% or more, more preferably 0.1% or more.

Li ₂ O excessively lowers the strain point and low-temperature viscosity to facilitate stress relaxation, and as a result, the stress value of the compressive stress layer may be lowered. Therefore, it is preferably 12% or less, more preferably 10% or less. It is particularly preferable that it is not substantially contained.

The _{Li 2 O, Na 2 O,} K 2 O but is a preferred ingredient in view of improving the chemical strengthening properties, _while, Li 2 _O, non-bridging oxygen constituting the _{Na 2 O, K 2 O (} Non- Bridging Oxygen (NBO) reduces DUV resistance. From the viewpoint of DUV resistance, less non-crosslinked oxygen is preferable, and Li ₂ O, Na ₂ O, K ₂ O represented by [2 × (Li ₂ O + Na ₂ O + K ₂ O—Al ₂ O ₃ ) / SiO ₂ ] is preferable. , Al ₂ O ₃ and SiO ₂ content are preferably 0.5 or less, more preferably 0.4 or less, still more preferably 0.35 or less, and particularly preferably 0.3 or less. Moreover, 0.02 or more is preferable from the point of a chemical strengthening characteristic, 0.05 or more is more preferable, 0.08 or more is further more preferable, 0.1 or more is especially preferable.

When Li ₂ O is not contained, it is preferable that [2 × (Na ₂ O + K ₂ O—Al ₂ O ₃ ) / SiO ₂ ] is 0.5 or less from the viewpoint of DUV resistance, The following is more preferable, 0.35 or less is further preferable, and 0.3 or less is particularly preferable. Moreover, 0.02 or more is preferable from the point of a chemical strengthening characteristic, 0.05 or more is more preferable, 0.08 or more is further more preferable, 0.1 or more is especially preferable.

MgO is a component that can stabilize the glass, improve the solubility, and reduce the alkali metal content by adding this to suppress an increase in the coefficient of thermal expansion (CTE). The content of MgO is preferably 1% or more, more preferably 2% or more. Further, the upper limit is preferably 15% or less, more preferably 12% or less. When the content of MgO is 1% or more, the CTE increase suppression effect is exhibited. On the other hand, when the content of MgO is 15% or less, the difficulty of devitrification is maintained, or a sufficient ion exchange rate is obtained.

CaO is a component that stabilizes the glass, and has the effect of improving the solubility while preventing devitrification due to the presence of MgO and suppressing an increase in CTE. The CaO content is preferably 0 to 5%, more preferably 0 to 1%. When the content of CaO is 5% or less, a sufficient ion exchange rate is obtained, and a desired DOL is obtained. Moreover, when it is desired to particularly improve the ion exchange performance in chemical strengthening, CaO is less than 1%, preferably 0.5% or less.

CaO / MgO is preferably 0.5 or less from the viewpoint of improving ion exchange performance in chemical strengthening and increasing the transmittance of the glass plate.
Further, SO 3 as a refining agent for molten _glass, chloride, fluoride or the like may also contain appropriate.

SrO may be contained as necessary, but since the effect of lowering the ion exchange rate is greater than that of MgO and CaO, SrO is not substantially contained or even if contained. The content is preferably 3% or less. In the present specification, “substantially not containing” means that the content is of the order of impurities, preferably less than 0.05%, more preferably less than 0.01%.

BaO has the greatest effect of reducing the ion exchange rate among alkaline earth metal oxides. Therefore, BaO is not substantially contained or even if contained, its content is 3% or less. Preferably there is.

When SrO or BaO is contained, the total content thereof is preferably 1% or less, more preferably less than 0.3%.

When one or more of CaO, SrO, and BaO are contained, the total content of these three components is preferably less than 3%. When the total is less than 3%, a decrease in ion exchange rate can be avoided. Typically 1% or less.

SnO ₂ is a component that makes DUV resistance better. The content of SnO ₂ is preferably 0.001% or more, more preferably 0.005% or more, still more preferably 0.01% or more, and particularly preferably 0.02% or more. On the other hand, SnO ₂ reduces the solarization resistance, so 1% or less is preferable, 0.7% or less is more preferable, 0.5% or less is more preferable, and 0.3% or less is particularly preferable.

CeO ₂ is a component that makes DUV resistance more excellent, but greatly reduces the resistance to solarization. CeO ₂ is preferably less than 0.1%, more preferably less than 0.05%, further preferably less than 0.01%, and most preferably not contained.

As ₂ O ₃ is a component that makes DUV resistance more excellent and promotes clarification of the glass batch, but has a high environmental load. Therefore, it is most preferable that As ₂ O ₃ is not substantially contained.

The glass according to the present invention is a colorless glass and is preferably used for display applications and the like. The colorless glass refers to a glass having a transmittance of 90% or more at a wavelength of 380 to 780 nm before UV irradiation. The transmittance is more preferably 90.5% or more.
When used as a glass plate for display, it is preferable that substantially no coloring components other than TiO ₂ and Fe ₂ O ₃ are contained because the transmittance is lowered.

As the coloring _{component, CoO, CuO, V 2 O} 5, Cr 2 O 3, Pr 6 O 11, CeO 2, Bi 2 O 3, Eu 2 O 3, MnO, Er 2 O 3, NiO, Nd 2 O 3 And at least one selected from the group consisting of WO ₃ , Rb ₂ O and Ag ₂ O.

Other components that may be included include SO ₃ , ZnO ₂ , Cs ₂ O, Fr ₂ O, SeO ₂ , and the like.
These can be contained in a total of 0 to 3%.

The aluminosilicate glass according to the present invention contains 50 to 80% of SiO _{2 in} terms of oxide-based mole percentage, and contains one or more of Li ₂ O, Na ₂ O and K ₂ O. The total Li ₂ O + Na ₂ O + K ₂ O content of Li ₂ O, Na ₂ O and K ₂ O is preferably 5 to 25%.

The aluminosilicate glass according to the present invention is expressed in terms of mole percentage based on oxides, and SiO ₂ is 60 to 70%, Al ₂ O ₃ is 7.5 to 18%, Li ₂ O, Na ₂ O, and K ₂ O. Any one or more total 5 to 25%, MgO 0 to 15%, CaO 0 to 5%, Fe ₂ O ₃ 0.001 to 0.022% and TiO ₂ 0.011 to 0.8 %, Or 0.7 to 4% of ZrO _2, and the total content of other components is preferably 3% or less. The content expressed in terms of mole percentages based on oxides of Li ₂ O, Na ₂ O, K ₂ O, Al ₂ O ₃ and SiO ₂ is [2 × (Li ₂ O + Na ₂ O + K ₂ O—Al ₂ O ₃ ) / SiO ₂ ] ≦ 0.5 is preferably satisfied.

The aluminosilicate glass according to the present invention is expressed in terms of mole percentages based on oxides, with SiO ₂ 63-66%, Al ₂ O ₃ 9-12%, Na ₂ O 14-17%, K ₂ O 0 Contains 1 to 1%, MgO 7 to 9%, CaO 0 to 1%, Fe ₂ O ₃ 0.001 to 0.022%, TiO ₂ 0.011 to 0.8%. The total content is preferably 3% or less.

In order to obtain high DUV resistance, Ti is preferably present in the state of Ti ⁴⁺ ions in the glass, and is preferably not present in the state of Ti ³⁺ ions. Since Ti ³⁺ ions have absorption in the visible range, the glass may be colored.

By setting the redox ratio of the glass to less than 0.550, the ratio of Ti ⁴⁺ ions in the glass can be increased. The redox ratio is preferably 0.500 or less, and more preferably 0.450 or less. It is to be noted that the redox ratio, refers to the percentage of divalent iron Fe ²⁺ to the total amount of iron Fe contained in the glass, the amount of Fe ²⁺ in the glass was quantified by bipyridyl absorptiometry, ICP emission spectrometry total Fe content It can be determined quantitatively by an analytical method. The redox ratio can also be calculated by ^obtaining the ratio of divalent iron Fe ²⁺ and trivalent iron Fe ³⁺ contained in the glass from the spectrum of the glass.

By setting the optical basicity of the glass to 0.50 or more, the ratio of Ti ⁴⁺ ions in the glass can be increased. The optical basicity is preferably 0.52 or more, and more preferably 0.54 or more. The optical basicity Λ is defined as follows.

When the glass composition represented by mol% containing an oxide as a component contains Ci mol% of the oxide of the i-th component, the optical basicity Λ is expressed by the following equation.
Λ = 1−Σ [zi · ri (γi−1) / 2γi]
In the formula, Σ indicates summing up for the subscript i. The meaning of each code is as follows.
γi = 1.36 (xi−0.26),
zi: the valence of the cation in the oxide of the i-th component,
ri: ratio of the number of cations in the oxide of the i-th component to the total number of oxygen in the “glass composition represented by mol% notation containing oxide”,
xi: Pauling electronegativity of atoms bonded to oxygen in the i-th component oxide.

Optical basicity Λ is calculated by Duffy et al. Am. Chem. Soc. , 93 (1971) 6448, which is proposed as an index of basicity of glass, and can be obtained by simple calculation from the glass composition without performing measurement or complicated analysis or calculation.

The glass according to the present invention is preferably a glass plate, and the thickness (plate thickness) of the glass plate at that time may be 0.1 to 2 mm as a whole, and 0.2 to 1 mm is rigid and lightweight. From the viewpoint of compatibility, 0.3 to 0.8 mm is particularly preferable.

The glass transition temperature (Tg) of the glass according to the present invention is, for example, 550 ° C. or higher, preferably 570 ° C. or higher, more preferably 580 ° C. or higher, and further preferably 580 to 700 ° C. . When Tg is 550 ° C. or higher, it is advantageous in terms of suppression of stress relaxation and thermal warpage during chemical strengthening treatment.
Tg can be adjusted by adjusting the total amount of SiO ₂ and Al ₂ O _{3 and} the amount of alkali metal oxide and alkaline earth oxide.

The temperature T2 at which the glass according to the present invention has a viscosity of 10 ² dPa · s is preferably 1800 ° C. or lower, more preferably 1750 ° C. or lower. Although the minimum of T2 is not specifically limited, Usually, it is 1400 degreeC or more.
The temperature T4 at which the viscosity of the glass according to the present invention is 10 ⁴ dPa · s is preferably 1350 ° C. or lower.
The liquidus temperature of the glass according to the present invention is preferably lower than T4 and more preferably 20 ° C. lower than T4 from the viewpoint of suppressing devitrification during glass forming.

The thermal expansion coefficient CTE of the glass according to the present invention is, for example, 65 × 10 ⁻⁷ to 110 × 10 ⁻⁷ / K, preferably 70 × 10 ⁻⁷ to 105 × 10 ^{− in} the temperature range of 50 to 350 ° C. ⁷ / K, more preferably 74 × 10 ⁻⁷ to 100 × 10 ⁻⁷ / K. When the CTE is 65 × 10 ⁻⁷ / K or more, it is advantageous in terms of thermal expansion matching with metals and other substances. CTE can be adjusted by adjusting the amount of alkali metal oxide and alkaline earth oxide.

The specific gravity at room temperature of the glass according to the present invention is 2.35 to 2.6 g / cm ³ , preferably 2.38 to 2.5 g / cm ³ , more preferably 2.40 to 2.48 g / cm ³ . ³ .

The Young's modulus E of the glass according to the present invention is preferably 60 GPa or more. If it is less than 60 GPa, the crack resistance and breaking strength of the glass may be insufficient. More preferably, it is 68 GPa or more. The Young's modulus is typically 90 GPa or less, and more typically 88 GPa or less.

The Poisson's ratio σ of the glass of the present invention is preferably 0.28 or less. If it exceeds 0.28, the crack resistance of the glass may be insufficient. More preferably, it is 0.25 or less. The Poisson's ratio is typically 0.15 or more, more typically 0.17 or more.

The chemical strengthening treatment of the glass according to the present invention can be performed by a generally used method. For example, the method of immersing in the molten salt containing potassium nitrate is mentioned.

The glass after chemical strengthening treatment (chemically strengthened glass) preferably has a CS of 300 to 1500 MPa, more preferably 650 to 1300 MPa. If it is less than 300 MPa, scratches are likely to occur on the surface of the glass, and there is a possibility that a practically sufficient strength cannot be obtained.
The compressive stress layer depth (DOL; Depth of Layer) is preferably 10 to 100 μm, and more preferably 15 to 90 μm. If the surface is less than 10 μm, if the surface of the glass is scratched, the depth of the scratch may exceed the DOL and the glass may be easily broken.
If CS is too large or DOL is too deep, the tensile stress value (CT; Center Tension) at the center of the glass becomes too large and may be crushed when the glass breaks. The values of CS and DOL can be measured with a surface stress meter.

<Method for producing glass plate>
The manufacturing method of the glass plate in this invention is not specifically limited, The method of shape | molding molten glass into a plate-shaped glass plate is not specifically limited. For example, appropriate amounts of various raw materials are prepared, heated to about 1500-1700 ° C and melted, and then homogenized by defoaming, stirring, etc., and the plate is obtained by a well-known float method, downdraw method (fusion method, etc.), press method Or cast into a block shape, and after slow cooling, cut into a desired size to produce a glass plate. A polishing process is performed as necessary, but it is also possible to treat the glass plate surface with a fluorine agent in addition to or instead of the polishing process.

The glass plate of the present invention is the size of a display such as a tablet PC or a smartphone or the size of a window glass of a building or a house. The glass of the present invention is generally cut into a rectangle, but other shapes such as a circle or a polygon may be used without any problem, and a glass subjected to drilling is also included.

The glass after production is expressed in terms of mole percentage based on oxide, Fe ₂ O ₃ : 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8% and ZrO ₂ : 0.7 to 4. Transmittance at a wavelength of 380 to 780 nm after treatment under the following condition 1 including at least one of 0% and Al ₂ O ₃ : 7.5 to 18%, not including As ₂ O ₃ The glass raw material is selected so that the glass is 80% or more.
(Condition 1) The glass was heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then irradiated with a low-pressure mercury lamp having a wavelength of 254 nm and an illuminance of 8 mW / cm ² for 10 minutes.

Furthermore, it is preferable to chemically treat the glass. Prior to the chemical strengthening treatment, it is preferable to perform shape processing according to the application, for example, mechanical processing such as cutting, end surface processing and drilling processing.
For example, the chemical strengthening treatment is performed by cutting the manufactured glass to a desired size to obtain a glass plate, and then preheating the glass plate to about 400 ° C., and in the molten salt, Na on the surface of the glass plate and K in the molten salt. Can be processed by ion exchange.
Further, after ion exchange in a molten salt containing a specific salt, an acid treatment and an alkali treatment may be performed to obtain a chemically strengthened glass plate having higher strength.

Examples of the molten salt for performing the ion exchange treatment include alkali nitrates such as potassium nitrate, potassium sulfate and potassium chloride, alkali sulfates and alkali chloride salts. These molten salts may be used alone or in combination of two or more. Further, a salt containing sodium may be mixed in order to adjust the chemical strengthening characteristics.

The CS of the chemically strengthened glass can be adjusted by adjusting the Na concentration, the strengthening time, and the molten salt temperature in the molten potassium nitrate salt used for ion exchange. In order to obtain higher CS, the Na concentration in the molten potassium nitrate is reduced.
DOL can be adjusted by adjusting Na concentration, strengthening time and molten salt temperature in the molten potassium nitrate salt used for ion exchange. In order to obtain a higher DOL, the temperature of the molten salt is increased.

Chemically tempered glass can be cut after chemical tempering treatment. You may chamfer the cutting edge after cutting. The chamfering may be a mechanical grinding process or a method of treating with a chemical solution such as hydrofluoric acid.

The use of the glass of the present invention is not particularly limited. Since chemically strengthened glass has high mechanical strength, it is suitable for use in places where impact due to dropping or contact with other substances is expected.

Specifically, for example, mobile phones (including multifunctional information terminals such as smartphones), PHS, PDA, tablet terminals, notebook personal computers, game machines, portable music / video players, electronic books, electronic terminals, Cover glass for display parts such as watches, cameras or GPS, and cover glass for touch panel operation monitors of these devices, cover glass for cookers such as microwave ovens and oven toasters, top plates such as electromagnetic cookers, meters, There are protection applications for machines or devices such as cover glass for instruments such as gauges and glass plates for reading parts such as copying machines or scanners.

Also, for example, window glass for vehicles, ships, airplanes, etc., household or industrial lighting equipment, signals, guide lights, cover boards for electric bulletin boards, showcases, bulletproof glass, etc. can be mentioned. Examples include a cover glass for protecting a solar cell and a glass material for condensing for increasing the power generation efficiency of the solar cell.

Also, for example, there are various glass for mirror surfaces, and further, as a substrate for information storage media such as HDDs, and as a substrate for information recording media such as CDs, DVDs, and Blu-ray discs.

In addition, for example, it can be used as a building material such as an aquarium, dishes such as dishes and cups, various cooking utensils such as bottles or chopping boards, cupboards, shelf boards and walls of refrigerators, roofs or partitions.

In addition to these uses, chemically strengthened glass produced after the chemical strengthening treatment is optimal as a glass material for display incorporated in various image display devices such as liquid crystal, plasma, and organic EL.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.
<Production of Glass Plate (Glass Mother Composition A); Test Examples 1 to 14, 16, 20 to 24>
Test Examples 2-5, 9, 14, 16, 20-24 are Examples, and Test Examples 1, 6-8, 10-13, 15 are Comparative Examples.
Generally used glass raw materials and reagents were appropriately selected so that the composition described in Table 1 or Table 2 was obtained in terms of oxide-based molar ratio, and weighed to 400 g as glass.
The weighed raw materials were mixed, put into a platinum crucible, put into a 1650 ° C. resistance heating electric furnace, melted for 3 hours, defoamed and homogenized.
The obtained glass was poured into a mold material and held at a temperature of 710 ° C. for 1 hour, and then cooled to room temperature at a rate of 0.5 ° C./min to obtain a glass block. Next, the glass block was cut and polished, and both surfaces were mirror-finished to obtain a glass plate having a thickness of 1 mm. The plate thickness of the glass plate was measured with a digital micrometer.
About the obtained glass plate of Test Example 1, a coefficient of thermal expansion (CTE) and a glass transition temperature (Tg) were measured based on JIS R 1618: 2002 using a thermal dilatometer (manufactured by Bruker Ax, TD5000SA). As a result, the Tg was 662 ° C. and the average coefficient of thermal expansion at 50 to 350 ° C. was 80 × 10 ⁻⁷ / K. Moreover, it was 2.44 g / cm < ³ > when the specific gravity of the obtained glass plate was measured by the Archimedes method.

<Manufacture of glass plate (glass mother composition B); Test Example 15 (Comparative Example)>
Generally used glass raw materials and reagents were weighed to 400 g as glass so that the composition described in Table 1 was obtained in terms of the molar ratio based on the oxide.
The weighed raw materials were mixed, put in a platinum crucible, put in a resistance heating electric furnace at 1600 ° C., melted for 3 hours, defoamed and homogenized.
The obtained glass was poured into a mold material and held at a temperature of 600 ° C. for 1 hour, and then cooled to room temperature at a rate of 0.5 ° C./min to obtain a glass block. Next, the glass block was cut and polished, and both surfaces were mirror-finished to obtain a glass plate having a thickness of 1 mm. The plate thickness of the glass plate was measured with a digital micrometer.
When the obtained glass plate was measured in the same manner as in Test Example 1, the Tg was 511 ° C., and the average linear expansion coefficient at 50 to 350 ° C. was 88 × 10 ⁻⁷ / K. Moreover, the specific gravity of the obtained glass plate was 2.50 g / cm ³ .

<Production of glass plate (glass mother composition C); Test Examples 17 to 19 (Examples)>
Generally used glass raw materials and reagents were weighed to 400 g as glass so that the composition described in Table 2 was obtained in terms of oxide-based molar ratio.
The weighed raw materials were mixed, put into a platinum crucible, put into a 1650 ° C. resistance heating electric furnace, melted for 3 hours, defoamed and homogenized.
The obtained glass was poured into a mold material, held at a temperature of 650 ° C. for 1 hour, and then cooled to room temperature at a rate of 0.5 ° C./min to obtain a glass block. Next, the glass block was cut and polished, and both surfaces were mirror-finished to obtain a glass plate having a thickness of 1 mm. The plate thickness of the glass plate was measured with a digital micrometer.
The obtained glass plate of Test Example 17 was measured in the same manner as in Test Example 1. The Tg was 604 ° C., and the average linear expansion coefficient at 50 to 350 ° C. was 98 × 10 ⁻⁷ / K. The specific gravity was 2.48 g / cm ³ .

<Production of glass plate (glass mother composition D); Test Examples 25 to 29>
Test examples 26 to 29 are examples, and test example 25 is a comparative example.
Generally used glass raw materials and reagents were weighed to 1000 g as glass so that the composition described in Table 2 was obtained in terms of oxide-based molar ratio.
The weighed raw materials were mixed, put into a platinum crucible, put into a 1650 ° C. resistance heating electric furnace, melted for 3 hours, defoamed and homogenized.
The obtained glass was poured into a mold material, held at a temperature of 680 ° C. for 1 hour, and then cooled to room temperature at a rate of 1.0 ° C./min to obtain a glass block. Next, the glass block was cut and polished, and both surfaces were mirror-finished to obtain a glass plate having a thickness of 1 mm. The plate thickness of the glass plate was measured with a digital micrometer.
The obtained glass plate of Test Example 25 was measured in the same manner as in Test Example 1. As a result, Tg was 633 ° C., and the average linear expansion coefficient at 50 to 350 ° C. was 91 × 10 ⁻⁷ / K. Moreover, the specific gravity of the obtained glass plate was 2.46 g / cm ³ .

<Glass composition>
The composition of the obtained glass plate was identified by the fluorescent X-ray method, and it confirmed that it had a desired composition.

<DUV resistance>
The transmittance of the glass before DUV irradiation and after DUV irradiation according to Condition 1 was measured. Transmittance measurement after DUV irradiation under condition 1 means that the glass is heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then the glass plate is left on the table horizontally. Then, after irradiating light from a low-pressure mercury lamp (PL 21-200 manufactured by Sen Special Light Source, main wavelengths 185 nm and 254 nm) from a position 5 cm above the glass plate for 10 minutes, the transmittance at a wavelength of 380 nm was measured. At this time, the illuminance at 254 nm at the place where the glass plate was installed was 8 mW / cm ² (measured with an illuminance meter UV-M03A and a photoreceiver UV-SD25-M10 manufactured by Oak Manufacturing Co., Ltd.). The transmittance was measured with a spectrophotometer (trade name U-4100) manufactured by Hitachi High-Technologies Corporation.
The DUV-induced absorption Δα represented by the following formula was calculated, where T0 was the transmittance at a wavelength of 380 nm before light irradiation, and T1 was the transmittance at a wavelength of 380 nm after light irradiation. Note that the transmittance at a wavelength of 380 nm is the lowest among the transmittances at a wavelength of 380 to 780 nm both before and after the DUV irradiation. Therefore, if a transmittance of a desired value or more is obtained at a wavelength of 380 nm, it can be said that a transmittance of a desired value or more is obtained even at a wavelength of 380 to 780 nm.
Δα = -ln (T1 / T0)

The results of the DUV resistance test are shown in Tables 1 and 2 as “induced absorption after low-pressure mercury irradiation (DUV resistance)”. If the DUV-induced absorption Δα is less than 0.095, it can be said that the DUV resistance is excellent.

<Solarization resistance>
The glass was heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then the glass plate was left on the table horizontally, and a high-pressure mercury lamp (QRU-2161, manufactured by Oak Seisakusho) J, the main wavelength of 365 nm) was irradiated for 10 minutes from a position 15 cm above the glass plate, and the transmittance at a wavelength of 380 nm was measured. The transmittance was measured with a spectrophotometer (trade name U-4100) manufactured by Hitachi High-Technologies Corporation.
UV-induced absorption Δα ′ represented by the following formula was calculated, where T0 ′ is a transmittance at a wavelength of 380 nm before light irradiation, and T1 ′ is a transmittance at a wavelength of 380 nm after light irradiation.
Δα ′ = − ln (T1 ′ / T0 ′)

The results of the solarization resistance test are shown in Tables 1 and 2 as “induced absorption after high-pressure mercury irradiation (solarization resistance)”. If the UV-induced absorption Δα ′ is less than 0.095, it can be said that the solarization resistance is excellent.

<Transparency>
The transmittance at a wavelength of 380 to 780 nm was measured for the glass not irradiated with UV. The measurement was performed using a spectrophotometer (trade name U-4100) manufactured by Hitachi High-Technologies Corporation. Tables 1 and 2 show the results of the transmittance measurement at 380 nm, which was the wavelength with the lowest transmittance, as “UV unirradiated 380 nm transmittance (%)”.
Further, the results of transmittance measurement at a wavelength of 380 nm measured under the conditions described in the above <DUV resistance> or <Solarization resistance> are respectively “380 nm transmittance after low-pressure mercury irradiation” or “380 nm after high-pressure mercury irradiation”. Table 1 and Table 2 show the "transmittance (%)".

If the transmittance at a wavelength of 380 nm before UV irradiation is 90% or more, and the transmittance at a wavelength of 380 nm after UV irradiation or DUV irradiation at a long wavelength side is 80% or more, the transmittance is excellent, and solarization resistance and DUV It can be said that it is excellent in tolerance.

Also, before and after irradiating DUV to a glass with a thickness of 1 mm, the wavelength at which the transmittance was less than 1% was measured. The results are shown in “UV unirradiated transmittance <1% wavelength (nm)” and “Transmittance after low-pressure mercury irradiation <1% wavelength (nm)” in Tables 1 and 2. If the wavelength at which the transmittance is less than 1% is 280 nm or less, it can be said that a sufficient transmittance can be obtained at a wavelength of 380 to 780 nm, and the color of the transmitted color of the glass does not deteriorate.

<Absorption coefficient>
Based on the transmittance at a wavelength of 380 to 780 nm obtained by the method described in the above <Transparency>, the absorption coefficient α was calculated for the glass not irradiated with UV and the glass after irradiation with the low-pressure mercury lamp. The calculation results are shown in “UV non-irradiated 380 nm absorption coefficient (cm ⁻¹ )” and “low-pressure mercury irradiated 380 nm absorption coefficient (cm ⁻¹ )” in Tables 1 and 2, respectively.
The absorption coefficient α was calculated as follows, assuming that the absorption at 780 nm was zero.
α = 2.303 × log (T ₇₈₀ / Ti) / d
Ti: Transmittance of measurement wavelength (%)
_T780 : Transmittance (%) at a wavelength of 780 nm
d: Glass thickness (cm)
If the absorption coefficient at a wavelength of 380 nm before UV irradiation is 2.35 × 10 ⁻³ cm ⁻¹ or less and the absorption coefficient at a wavelength of 380 nm after DUV irradiation is 1.35 × 10 ⁻² cm ⁻¹ or less, the DUV resistance is improved. It can be said that it is excellent.

<Transparent color>
The transmission data L ^* , a ^* , and b ^* of the glass not irradiated with UV and the glass after DUV irradiation, and the transmittance measurement data obtained by the method described in the above <Transparency> are JIS Z8722: 2009. The tristimulus values X, Y, and Z of the object color are calculated based on the above, and are calculated by converting them into the L ^* a ^* b ^* color system based on these numerical values. The results are shown in “UV unirradiated transmission color” and “Transmission color after low-pressure mercury irradiation” in Tables 1 and 2, respectively. The value of the color tone b ^* after DUV irradiation is preferably 2.0 or less.

<Chromaticity change>
A difference (chromaticity change) ΔE in the chromaticity of the glass before and after irradiation with DUV was determined by the following formula. In the formula, L ₀ ^* , a ₀ ^* , and b ₀ ^* are values of UV non-irradiation obtained in the above <transmission color>, and L ^* , a ^* , and b ^* are obtained in the above <transmission color>. The obtained value after DUV irradiation was used. The results are shown in Table 1 and Table 2 “After irradiation with low-pressure mercury and before and after irradiation ΔE”. ΔE is preferably 2 or less.

<Chemical strengthening properties>
The glass plates of Test Examples 1 to 7, 9, 10, and 12 to 15 were immersed in molten potassium nitrate salt having a concentration of 100% and a temperature of 425 ° C. for 4 hours to perform chemical strengthening treatment. The glass plates of Test Examples 25 to 29 were immersed in molten potassium nitrate having a concentration of 100% and a temperature of 425 ° C. for 6 hours to perform chemical strengthening treatment. The value of CS (MPa) and DOL (μm) of the obtained chemically strengthened glass plate was calculated as a calculated value using a surface stress meter (manufactured by Orihara Seisakusho). The results are shown in Tables 1 and 2. FIG. 7 shows the relationship between the TiO ₂ content and DOL after the chemical strengthening treatment in Test Examples 1 to 7.
As chemical strengthening characteristics, it is preferable that the CS value is 650 MPa or more and the DOL value is 15 μm or more. The reduction rate of DOL due to addition of TiO ₂ and ZrO ₂ is preferably less than 10%. In Test Examples 1 to 15 for Glass A, the DOL value (25.1 μm) of the glass in Test Example 1 was used as a reference, and the decrease rate of DOL from the reference was defined as “DOL decrease rate (%)”. The DOL reduction rate is preferably less than 10%. In Test Examples 25 to 26 of Glass D, the DOL value (35.8 μm) of the glass in Test Example 25 was used as a reference, and the DOL decrease rate from the reference was defined as “DOL decrease rate (%)”. The DOL reduction rate is preferably less than 10%.

4 and 5 show transmittance spectra before and after the glass of Test Example 1 (Comparative Example) and the glass of Test Example 5 (Example) were irradiated with a low-pressure mercury lamp, respectively. As a result, when the glass does not contain TiO ₂ , the transmittance decreases over the entire wavelength range of 380 to 780 nm, whereas the inclusion of TiO ₂ almost prevents the decrease in transmittance. It can be seen that it is excellent in DUV resistance.

Figure 6 is a transmittance change in the wavelength 380nm before and after irradiation with a low-pressure mercury lamp on the glass, is a graph representing every TiO ₂ content in the glass by including TiO ₂ 0.011% or more, a low pressure mercury It is possible to satisfactorily prevent a decrease in transmittance after lamp irradiation.
Further, although the value of DOL after the chemical strengthening according TiO ₂ content is increased tends to be low, if the content of TiO ₂ is 0.011 to 0.8%, almost the DOL when not adding equivalent It was confirmed that the value of was obtained.

Although the present invention has been described in detail and 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. This application is based on a Japanese patent application filed on August 12, 2015 (Japanese Patent Application No. 2015-159455), the contents of which are incorporated herein by reference.

According to the present invention, it is possible to obtain a glass having excellent DUV resistance and solarization resistance, and excellent chemical strengthening properties with high transmission and small color change even after UV irradiation. Therefore, even if UV of each wavelength is irradiated before using the glass, highly transparent and high-strength glass can be obtained without coloration. Useful.

Claims (10)

1. In terms of mole percentage based on oxide, at least one of Fe ₂ O ₃ : 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8%, and ZrO ₂ : 0.7 to 4.0% On the other hand, Al ₂ O ₃ : 7.5 to 18%, As ₂ O ₃ is not included, and the transmittance at a wavelength of 380 to 780 nm after performing the treatment under the following condition 1 is 80% or more. Some glass.
   (Condition 1) The glass was heat-treated at (Tg + 40) ° C. for 1 hour, slowly cooled to room temperature at 0.5 ° C./minute, and then irradiated with a low-pressure mercury lamp having a wavelength of 254 nm and an illuminance of 8 mW / cm ² for 10 minutes.
2. The glass according to claim 1, wherein the absorption coefficient α at a wavelength of 380 to 780 nm after the treatment under the condition 1 is 1.35 × 10 ⁻² cm ⁻¹ or less.
3. The glass according to claim 1 or 2, wherein the color tone b ^* in the chromaticity coordinates of the L ^* a ^* b ^* color system after the treatment under the condition 1 is 2.0 or less.
4. In terms of oxide-based molar percentage, 50 to 80% of SiO ₂ is contained, and at least one of Li ₂ O, Na ₂ O and K ₂ O is contained, and Li ₂ O, Na ₂ O and K ₂ O total _Li 2 _{O +} Na 2 O + _{K 2} O content of 5-25%, the glass according to any one of claims 1 to 3.
5. The glass according to any one of claims 1 to 4, which contains substantially no coloring component other than TiO ₂ and Fe ₂ O ₃ .
6. The glass according to any one of claims 1 to 5, comprising SnO ₂ in an amount of 0.001 to 1% in terms of a molar percentage based on an oxide.
7. The content represented by the mole percentage display based on oxides of Na ₂ O, K ₂ O, Al ₂ O ₃ and SiO ₂ containing SiO ₂ and not containing Li ₂ O is [2 × (Na ₂ The glass according to any one of claims 1 to 6, which satisfies a relationship of O + K ₂ O-Al ₂ O ₃ ) / SiO ₂ ] ≦ 0.5.
8. In terms of oxide-based molar percentage, SiO ₂ is 60 to 70%, Al ₂ O ₃ is 7.5 to 18%, and any one or more of Li ₂ O, Na ₂ O, and K ₂ O is a total of 5 to 25%, MgO 0 to 15%, CaO 0 to 5%, Fe ₂ O ₃ 0.001 to 0.022%, TiO ₂ : 0.011 to 0.8% and ZrO ₂ : 0.7 to 4.0% of at least one of the other components, and the total content of other components is 3% or less, and Li ₂ O, Na ₂ O, K ₂ O, Al ₂ O ₃ and SiO ₂ oxides The content represented by the standard molar percentage display satisfies the relationship of [2 × (Li ₂ O + Na ₂ O + K ₂ O—Al ₂ O ₃ ) / SiO ₂ ] ≦ 0.5. Glass according to item.
9. Expressed in mole percentages based on oxides, SiO ₂ 63-66%, Al ₂ O ₃ 9-12%, Na ₂ O 14-17%, K ₂ O 0-1%, MgO 7-9 %, CaO 0 to 1%, Fe ₂ O ₃ 0.001 to 0.022%, TiO ₂ 0.011 to 0.8%, and the total content of other components is 3% or less. The glass according to any one of claims 1 to 7.
10. A chemically strengthened glass obtained by chemically strengthening the glass according to any one of claims 1 to 9.

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