KR20130056289A - Tempered glass, and tempered glass plate - Google Patents

Abstract

The tempered glass of the present invention is a tempered glass having a compressive stress layer on its surface, which is mol% as the glass composition, 50 to 75% SiO ₂ , 3 to 13% Al ₂ O ₃ , B ₂ O ₃ 0 to 1.5%, Li ₂ O 0-4%, Na ₂ O 7-20%, K ₂ O 0.5-10%, MgO 0.5-13%, CaO 0-6%, SrO 0-4.5%, and substantially As ₂ O ₃ , It is characterized by not containing Sb ₂ O ₃ , PbO, and F.

Description

Tempered Glass and Tempered Glass Plate {TEMPERED GLASS, AND TEMPERED GLASS PLATE}

FIELD OF THE INVENTION The present invention relates to tempered glass and tempered glass plates, and more particularly to tempered glass and tempered glass plates suitable for cell phones, digital cameras, PDAs (mobile terminals), cover glass of solar cells, or glass substrates of displays, especially touch panel displays. will be.

Devices such as mobile phones, digital cameras, PDAs, touch panel displays, large televisions, and non-contact power supplies are becoming more and more popular.

For these uses, tempered glass tempered by ion exchange treatment or the like is used (see Patent Document 1 and Non-Patent Document 1).

In particular, recently, tempered glass has been used as a display protection member of a large television. These protective members should have (1) high mechanical strength, and (2) have a liquid viscosity suitable for down-draw methods such as the overflow down draw method and the slit down draw method, float method, etc. in order to form large glass sheets in large quantities. , (3) high temperature viscosity suitable for molding, (4) reinforcement treatment can be performed at low cost and efficiently.

Japanese Patent Application Laid-Open No. 2006-83045

 Tezuro Izumiya et al., "New Glass and Its Physical Properties," First Edition, Institute for Management Systems, August 20, 1984, p.451-498

In order to raise the mechanical strength of tempered glass, it is necessary to raise the compressive stress value of a compressive stress layer. Al ₂ O ₃ as a component to increase the compressive stress value Such components are known. However, when the content of Al ₂ O ₃ is too high, the devitrification resistance decreases, and it becomes difficult to obtain liquid viscosity suitable for down draw methods such as the overflow down draw method and the slit down draw method, float method, etc. It becomes difficult to obtain a molding temperature suitable for the back.

In addition, the use of KNO ₃ dissolved salts allows ion glass treatment of large glass plates continuously and in large quantities. However, the use of KNO ₃ over time as sea salt is sea salt for this degradation for KNO ₃ there is a problem that must be frequently exchanged for the sea salt KNO _3. Since the bath exchange of KNO ₃ molten salt takes time and cost, the efficiency of ion exchange treatment falls, and the manufacturing cost of tempered glass tends to be higher.

In addition, when the large glass plate is tempered, there is a problem that warpage occurs in the tempered glass plate due to the characteristic difference between the front and back surfaces (facing surfaces) of the glass plate. Moreover, in this case, the glass plate temporarily bent by the residual stress in the planar direction during the reinforcement treatment, which causes a problem that the glass plate bends due to this. In recent years, there is a demand for thinning of the tempered glass sheet, but in this case, the problem becomes particularly remarkable.

Therefore, the technical problem of the present invention is to create a tempered glass and a tempered glass plate which have high ion exchange performance and devitrification resistance, are resistant to deterioration of KNO ₃ molten salt, and are hard to bend even when the large glass sheet is tempered. .

MEANS TO SOLVE THE PROBLEM As a result of carrying out various examinations, the present inventors find what can solve the said technical problem by strictly restricting a glass composition, and propose as this invention. That is, the tempered glass of the present invention is a tempered glass having a compressive stress layer on its surface, and SiO _{2 in} mol% as a glass composition. 50 to 75%, Al ₂ O ₃ 3 to 13%, B ₂ O ₃ 0 to 1.5%, Li ₂ O 0 to 4%, Na ₂ O 7 to 20%, K ₂ O 0.5 to 10%, MgO 0.5 to 13%, CaO 0-6%, SrO 0-4.5%, and are substantially free of As ₂ O ₃ , Sb ₂ O ₃ , PbO, and F. Here, "substantially does not contain As ₂ O ₃ " is intended to allow the case where As ₂ O ₃ is not actively added as a glass component but mixed as impurities, specifically, the content of As ₂ O ₃ is It indicates that it is less than 0.05 mol%. The term "substantially does not contain Sb ₂ O ₃ " is intended to allow the case where Sb ₂ O ₃ is not actively added as a glass component, but is mixed as impurities. Specifically, the content of Sb ₂ O ₃ is 0.05 mol%. It is less than The term "substantially does not contain PbO" is intended to permit the case where PbO is not actively added as a glass component, but is incorporated as an impurity, and specifically, the content of PbO is less than 0.05 mol%. The term "substantially does not contain F" is intended to allow the case where F is not actively added as a glass component but is mixed as an impurity, and specifically, the content of F is less than 0.05 mol%.

MEANS TO SOLVE THE PROBLEM The present inventors came to acquire the following knowledge as a result of various examination. By simultaneously regulating the content (or content ratio) of Al ₂ O ₃ and MgO, ion exchange performance and devitrification resistance can be improved. By regulating the content (or content ratio) of Al ₂ O ₃ and the alkali metal oxide at the same time, the devitrification resistance can be improved. By adding a predetermined amount of K ₂ O, the thickness of the compressive stress layer can be increased. By simultaneously regulating the content (or content ratio) of K ₂ O and Na ₂ O, the thickness of the compressive stress layer can be thickened without lowering the compressive stress value of the compressive stress layer.

In addition, if the glass composition is regulated in the above range, even if the deteriorated KNO ₃ dissolved salt is used, the compressive stress value and thickness of the compressive stress layer are not extremely reduced, so that the exchange frequency of the KNO ₃ dissolved salt can be reduced.

Secondly, the tempered glass of the present invention is a glass composition in mol% of SiO ₂ 50-75%, Al ₂ O ₃ 4-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-2%, Na ₂ O 9-18%, K ₂ O 1-8%, MgO 0.5-12%, CaO 0-3.5%, to contain _{SrO 0 ~ 3%, TiO 2} 0 ~ 0.5% is preferred.

Thirdly, the tempered glass of the present invention has a glass composition in mol% of SiO ₂ 50-75%, Al ₂ O ₃ 4-12%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na to contain _{2 O 10 ~ 17%, K} 2 O 2 ~ 7%, MgO 1.5 ~ 12%, CaO 0 ~ 3%, SrO 0 ~ 1%, TiO 2 0 ~ 0.5% is preferred.

Fourthly, the tempered glass of the present invention has a glass composition in mol% of SiO ₂ 55-75%, Al ₂ O ₃ 4-11%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 10-16%, K ₂ O 2-7%, MgO 3-12%, CaO 0-3%, SrO 0-1%, ZrO ₂ 0.5-10%, TiO ₂ 0-0.5% desirable.

Fifthly, the tempered glass of the present invention has a glass composition in mol% of SiO ₂ 55-69%, Al ₂ O ₃ 4-11%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 11-16%, K ₂ O 2-7%, MgO 3-9%, CaO 0-3%, SrO 0-1%, ZrO ₂ 1-9%, TiO ₂ It is preferable to contain 0 to 0.1%.

Sixthly, in the tempered glass of the present invention, the compressive stress value of the compressive stress layer is 300 MPa or more, and the thickness (depth) of the compressive stress layer is preferably 10 µm or more. Here, the "compressive stress value of the compressive stress layer" and the "thickness of the compressive stress layer" refer to the interference pattern observed when the sample is observed using a surface stress gauge (for example, FSM-6000 manufactured by Toshiba Corporation). It indicates the number and the value that is calculated from the interval.

Seventh, the tempered glass of the present invention preferably has a deterioration coefficient (D) of 0.01 to 0.6. Here, the deterioration coefficient (D) is - the value calculated by the formula / the compressive stress value (new KNO ₃ sea salt for) (compressive stress value (new KNO ₃ sea salt for) compressive stress value (deterioration KNO ₃ sea salt for)) Point. Here, "degraded KNO ₃ molten salt" refers to KNO ₃ molten salt containing about 1500 ppm of Na ₂ O and about 20 ppm of Li ₂ O, and can be produced by, for example, the following method. 58.7 mass% of SiO ₂ , 12.8 mass% of Al ₂ O ₃ , 0.1 mass% of Li ₂ O, 14.0 mass% of Na ₂ O, 6.3 mass% of K ₂ O, 2.0 mass% of MgO, 2.0 mass% of ZrO _2, 4.1 mass% of ZrO ₂ The glass having a glass composition of pulverized is pulverized, glass powder not passed through the sieve opening 300 µm and not passing through the sieve opening 150 µm is collected to obtain a glass powder having an average particle diameter of 225 µm. Subsequently, 95 g of this glass powder is put into a basket made of a metal mesh having a sieve opening of 100 µm. Subsequently, the glass powder is immersed in 400 ml of KNO ₃ maintained at 440 ° C. for 60 hours (the basket is shaken up and down 10 times every 24 hours). On the other hand, "New KNO ₃ for sea salt" denotes a non-service KNO ₃ sea salt for the ion exchange treatment in the past, the content of Na ₂ O 200ppm or less, Li ₂ O content refers to sea salt for 3ppm or less KNO _3.

Eighthly, the tempered glass of the present invention preferably has a liquidus temperature of 1075 ° C or lower. Here, "liquid temperature" means that after passing through a standard sieve 30 mesh (sieving opening 500 micrometers) and leaving the glass powder which remained at 50 mesh (sieving opening 300 micrometers) in a platinum boat, and maintaining in a temperature gradient 24 hours, The precipitation temperature is indicated.

Ninth, the tempered glass of the present invention preferably has a liquidus viscosity of 10 ^4.0 dPa · s or more. Here, "liquid viscosity" points out the value which measured the viscosity of the glass in liquidus temperature by the platinum ball pulling-up method.

Claim 10, the tempered glass of the present invention preferably has a temperature of not more than 1250 ℃ in 10 ^4.0 dPa · s. Here, "the temperature in 10 ^4.0 dPa * s" points out the value measured by the platinum ball pulling-up method.

Eleventh, the tempered glass of the present invention preferably has a density of 2.6 g / cm 3 or less. Here, "density" can be measured by the well-known Archimedes method.

12thly, it is preferable that the tempered glass of this invention is 65 GPa or more. Here, "Young's modulus" can be measured by a well-known resonance method or the like.

13thly, the tempered glass plate of this invention consists of the tempered glass in any one of said above, It is characterized by the above-mentioned.

14thly, it is preferable that the tempered glass plate of this invention is shape | molded by the float method.

Fifteenth, it is preferable that the tempered glass sheet of the present invention has a surface which is polished by 0.5 µm or more in the thickness direction.

16th, it is preferable that the difference ((DELTA) CS) of the compressive stress value of the compressive stress layer of the facing surface of the tempered glass plate of this invention is 50 Mpa or less. In the case of forming the glass plate by the float method, a difference occurs in the compressive stress value of the compressive stress layer formed even when the ion exchange treatment is similarly performed on the surface not in contact with the surface in contact with the molten tin, and is particularly large and thin. In the case of a tempered glass sheet, warpage tends to occur. Therefore, when (DELTA) CS is made into the said range, it becomes easy to prevent such a defect.

Seventeenth, the tempered glass sheet of the present invention is a tempered glass sheet having a compressive stress on its surface, the length of which is at least 500 mm, the width is at least 500 mm, the thickness is 0.5 to 1.5 mm, the Young's modulus is 65 GPa or more, and the compressive stress of the compressive stress layer. The value is 200 MPa or more, the thickness of the compressive stress layer is 20 µm or more, the deterioration coefficient (D) is 0.6 or less, and the difference (ΔCS) of the compressive stress values of the compressive stress layer on the opposing surface is 50 MPa or less.

Nineteenth, the tempered glass plate of the present invention is preferably used for a touch panel display.

Nineteenth, the tempered glass sheet of the present invention is preferably used for a cover glass of a cellular phone.

20thly, it is preferable that the tempered glass plate of this invention is used for the cover glass of a solar cell.

Twenty-first, the tempered glass sheet of the present invention is preferably used for a protective member of a display.

Twenty-second, the tempered glass sheet of the present invention is a tempered glass sheet having a compressive stress on the surface of 50% to 75% SiO ₂ , 4 to 12% Al ₂ O ₃ , 0 to 1% B ₂ O _{3 in} mol% as a glass composition, Li ₂ O 0 ~ 1%, Na ₂ O 10 ~ 17%, K ₂ O 2 ~ 7%, MgO 1.5 ~ 12%, CaO 0 ~ 3%, SrO 0 ~ 1%, TiO ₂ 0 ~ 0.5% The molar ratio [MgO / (MgO + CaO)] is 0.5 or more, length is 500 mm or more, width is 500 mm or more, thickness is 0.5-1.5 mm, Young's modulus is 65 GPa or more, and the compressive stress value of a compressive stress layer is 400 MPa or more, the thickness of a compressive stress layer is 30 micrometers or more, and the deterioration coefficient (D) is 0.4 or less, It is characterized by the above-mentioned.

Twenty-third, the tempered glass of the present invention is a tempered glass provided to the tempered treatment, 50 to 75% SiO ₂ , Al ₂ O _{3 in} mol% as a glass composition 3-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-4%, Na ₂ O 7-20%, K ₂ O 0.5-10%, MgO 0.5-13%, CaO 0-6%, It is characterized by containing 0-4.5% of SrO and substantially free of As ₂ O ₃ , Sb ₂ O ₃ , PbO, and F.

Twenty-fourth, the tempered glass sheet of the present invention is a tempered glass sheet provided in the tempering process, the plate thickness is 1.5 mm or less, and the maximum value Fmax of the residual stress in the planar direction with respect to the entire planar portion of the tempered glass sheet is It is characterized by being 5 MPa or less. Here, "Fmax" is a birefringent measuring device made by Uniopt Co., Ltd .: ABR-10A in a glass plate having a dimension of 500 mm x 500 mm or more (particularly 1 m x 1 m): It is the maximum value when the birefringence (unit: nm) near the outer peripheral part is measured and converted into residual stress in the planar direction. In addition, by measuring optical birefringence, that is, measuring optical path differences of orthogonal linearly polarized waves, the residual stress value in the glass plate can be estimated, and the deviation stress [F (MPa)] caused by the residual stress is F = R / It is represented by the formula of CL. In addition, "R" is an optical path difference (nm), "L" is the distance (cm) which the polarization wave passed, and "C" is a photoelastic constant (proportional constant), Usually 20-40 (nm / cm) / It becomes the value of (MPa). In addition, although the tensile stress and the compressive stress exist in the residual stress in the planar direction, the absolute values of both are evaluated above.

(Effects of the Invention)

Since the tempered glass of this invention has high ion exchange performance, even if it is a short time ion exchange process, the compressive stress value of a compressive stress layer becomes high and a compressive stress value is formed deep. For this reason, mechanical strength becomes high and the nonuniformity of mechanical strength becomes small.

Moreover, since the tempered glass of this invention is excellent in devitrification resistance, it can shape | mold efficiently by the overflow down draw method, the float method, etc. In addition, if it is an overflow down draw method, a float method, etc., a large and thin glass plate can be shape | molded in large quantities.

In addition, since the tempered glass of the present invention has a small deterioration coefficient (D), the compressive stress value and thickness of the compressive stress layer formed even after ion exchange treatment over a long period of time are less likely to decrease, thereby reducing the exchange frequency of KNO ₃ dissolved salts. Can be.

1 is data showing residual stress in the planar direction of the glass plate according to [Example 3].
2 is data showing residual stress in the planar direction of the glass plate according to [Example 4].

The tempered glass according to the embodiment of the present invention has a compressive stress layer on the surface, and as a glass composition, SiO ₂ 50 to 75%, Al ₂ O ₃ 3 to 13%, B ₂ O ₃ 0 to 1.5%, Li ₂ O 0-4%, Na ₂ O 7-20%, K ₂ O 0.5-10%, MgO 0.5-13%, CaO 0-6%, SrO 0-4.5%, substantially As ₂ O ₃ , Sb ₂ O ₃ , PbO, and F are not included. In addition, unless otherwise indicated, in description of the containing range of each component,% display shall indicate mol%.

As a method of forming a compressive stress layer on the surface, there are a physical strengthening method and a chemical strengthening method. It is preferable that the tempered glass of this embodiment is produced by the chemical strengthening method.

The chemical strengthening method is a method of introducing alkali ions having a large ion radius to the surface of the glass by ion exchange treatment at a temperature below the strain point of the glass. When the compressive stress layer is formed by chemical strengthening, the compressive stress layer can be appropriately formed even when the glass is thin, and even when the tempered glass is cut after forming the compressive stress layer, the glass is tempered like the physical strengthening method such as the wind cooling method. Is not easily destroyed.

In the tempered glass of this embodiment, the reason which limited the content range of each component as mentioned above is shown below.

SiO ₂ is a component that forms a network of glass. The content of SiO ₂ is 50 to 75%, preferably 55 to 75%, 55 to 72%, 55 to 69%, particularly 58 to 67%. If the content of SiO ₂ is too small, it becomes difficult to vitrify. Further, the thermal expansion coefficient becomes too high, and the thermal shock resistance tends to decrease. In addition, the deterioration coefficient D tends to be large. On the other hand, is apt to have a content of SiO ₂ is too large, the melting property and formability decreases. In addition, the thermal expansion coefficient becomes too low, making it difficult to match the thermal expansion coefficient of the surrounding material.

Al ₂ O ₃ is a component that increases ion exchange performance and has the highest effect of reducing the deterioration coefficient (D). It is also a component that increases distortion and Young's modulus. The content of Al ₂ O ₃ is 3 to 13%. If the content of Al ₂ O ₃ is too small, there tends to increase the degradation coefficient (D), also occurs a fear that can not sufficiently exhibit the ion exchange performance. Thus, a suitable lower limit of Al ₂ O ₃ is at least 4%, at least 4.5%, at least 5%, at least 5.5%, at least 6%, at least 7%, at least 8.5%, at least 10%, in particular at least 10.5%. On the other hand, when the content of Al ₂ O ₃ so liable to be too large, the devitrification crystals were precipitated in the glass is difficult to form the glass sheet by a float process or the like overflow down draw method. In addition, the thermal expansion coefficient becomes too low, making it difficult to match the thermal expansion coefficient of the surrounding material. Moreover, high temperature viscosity becomes high and meltability will fall easily. Therefore, a suitable upper limit range of Al ₂ O ₃ is 12.5% or less, in particular 12% or less.

B ₂ O ₃ is a component that lowers the high temperature viscosity and density, stabilizes the glass, makes it difficult to precipitate crystals, and lowers the liquidus temperature. However, when the content of B ₂ O ₃ is too large, coloring of the glass surface, referred to as geueulrim by ion exchange occurs, or water resistance is deteriorated and, liable to be thinner a thickness of the compressive stress layer. Therefore, the content of B ₂ O ₃ is 0 to 1.5%, preferably 0 to 1.3%, 0 to 1.1%, 0 to 1%, 0 to 0.8%, 0 to 0.5%, particularly preferably 0 to 0.1 %to be.

Li ₂ O is an ion exchange component, a component that lowers the viscosity at high temperature to increase meltability and formability, and increases the Young's modulus. In addition, Li ₂ O has a great effect of increasing the compressive stress value in the alkali metal oxide, but when the content of Li ₂ O is extremely high in a glass system containing 7% or more of Na ₂ O, the compressive stress value tends to decrease. There is this. In addition, when the content of Li ₂ O is too large, the liquidus viscosity is lowered and in addition makin liable to devitrification of glass is too high and the thermal expansion coefficient or the thermal shock resistance is lowered, it becomes difficult to match the coefficient of thermal expansion of the surrounding material. Moreover, low temperature viscosity may fall too much, stress relaxation will arise easily, and a compressive stress value may fall rather. In addition, the deterioration coefficient D tends to be large. Therefore, the content of Li ₂ O is 0 to 4%, preferably 0 to 2.5%, 0 to 2%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, particularly preferably 0 to 0.3% to be.

Na ₂ O is an ion exchange component, and is a component that lowers the high temperature viscosity to increase meltability and formability. In addition, Na ₂ O is also a component that improves resistance to insolubility. When the content of Na ₂ O is too small, the melting property is degraded, or, the thermal expansion coefficient is reduced, or is likely to have the ion exchange performance. Therefore, the content of Na ₂ O is at least 7%, and the suitable lower limit range is at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, in particular at least 13%. On the other hand, becomes high when the content of Na ₂ O is too large, the thermal expansion coefficient is excessively reduced or the thermal shock resistance, it is difficult to match the coefficient of thermal expansion of the surrounding material. Moreover, a strain point may fall too much, or may lack the component balance of a glass composition, and may rather fall in devitrification resistance. In addition, the deterioration coefficient D tends to be large. Therefore, the content of Na ₂ O is a suitable upper limit is not more than 20%, is 19% or less, 17% or less, particularly 16% or less.

K ₂ O is a component that promotes ion exchange, and is an ingredient that tends to thicken the compressive stress layer in an alkali metal oxide. And is a component that lowers the high-temperature viscosity to improve the meltability and moldability. It is also a component that improves the devitrification resistance. Therefore, the content of K ₂ O is 0.5% or more, a suitable lower limit is not less than, in particular more than 2% 1.5%, 1% or more. However, the high and the content of K ₂ O is too large, the thermal expansion coefficient is excessively reduced or the thermal shock resistance, it is difficult to match the coefficient of thermal expansion of the surrounding material. Moreover, there exists a tendency for a strain point to fall too much, or to lack the component balance of a glass composition, but rather to reduce devitrification resistance. Therefore, the content of K ₂ O is less than 10%, and a suitable upper limit is less than 9%, 8%, 7% or less, particularly 6% or less.

Suitable contents of Li ₂ O + Na ₂ O + K ₂ O are 10-25%, 13-22%, 15-20%, 16-20%, 16.5-20%, especially 18-20%. When the content of _{Li 2 O + Na 2 O +} K 2 O is likely to be too small, the ion exchange performance or meltable reduced if. On the other hand, when the content of _{Li 2 O + Na 2 O +} K 2 O is too large, the deterioration coefficient (D) is too large. In addition, the glass tends to devitrify, and in addition, the coefficient of thermal expansion becomes too high, whereby the thermal shock resistance is lowered, or it is difficult to match the thermal expansion coefficient of the surrounding material. Moreover, a strain point may fall too much and it may become difficult to obtain a high compressive stress value. Moreover, the viscosity near liquidus temperature may fall, and it may become difficult to ensure a high liquidus viscosity. Further, _{"Li 2 O + Na 2 O +} K 2 O " is the total amount of Li ₂ O, Na ₂ O, and K ₂ O.

In the glass in composition according to the present embodiment will be described factors when the content of _{Li 2 O + Na 2 O +} K 2 O affecting deterioration coefficient (D). In the present embodiment, it is formed a compressive stress layer on the glass surface by the mainly ion exchange of Na ion and K ion because the content of Li ₂ O is suppressed to 4% or less. When the content of Li ₂ O + Na ₂ O + K ₂ O decreases, the content of ion-exchanged components decreases, so the compressive stress value decreases, whereas the content of Li ₂ O + Na ₂ O + K ₂ O decreases. When too much, ion exchange of Na ion and K ion (formation of a compressive stress layer) is promoted, and ion exchange between Li ions and Na ions contained in KNO ₃ is more likely to occur in preference to ion exchange between Na ions and K ions. When ion exchange of Li ion and Na ion occurs, it is thought that a compressive stress value falls because tensile stress is formed.

The suitable range of molar ratio (Li ₂ O + Na ₂ O + K ₂ O) / Al ₂ O ₃ is 1-3. When the molar ratio (Li ₂ O + Na ₂ O + K ₂ O) / Al ₂ O ₃ is too large, the strain point is lowered, and the ion exchange performance tends to be lowered, or the component balance of the glass composition is poor, and the devitrification resistance tends to be lowered. . Moreover, there exists a possibility that the deterioration coefficient D may become large. However, when the molar ratio (Li ₂ O + Na ₂ O + K ₂ O) / Al ₂ O ₃ is too small, the viscosity of the glass becomes too high and the bubble quality is lowered, or the component balance of the glass composition is poor, and the devitrification resistance tends to decrease. Lose. The suitable lower limit of the molar ratio (Li ₂ O + Na ₂ O + K ₂ O) / Al ₂ O ₃ is 1 or more, 1.2 or more, 1.4 or more, 1.5 or more, 1.7 or more, in particular 1.8 or more, and the molar ratio (Li ₂ O + A suitable upper limit of Na ₂ O + K ₂ O) / Al ₂ O ₃ is 3 or less, 2.8 or less, 2.6 or less, 2.5 or less, especially 2.3 or less. In the case where the deterioration coefficient (D) is important, the lower limit of the molar ratio (Li ₂ O + Na ₂ O + K ₂ O) / Al ₂ O ₃ is preferably 1 or more, particularly preferably 1.2 or more, and the molar ratio (Li ₂ O). The upper limit of + Na ₂ O + K ₂ O) / Al ₂ O ₃ is preferably at most 3, at most 2.5, at most 2, at most 1.8, at most 1.5, particularly preferably at most 1.4. In addition, the molar ratio _{(Li 2 O + Na 2 O} + K 2 O) / Al 2 O ₃ is a preferred range of 1 to 3, 1.2 to 3, particularly preferably 1.2 to 2.5. By regulating the molar ratio (Li ₂ O + Na ₂ O + K ₂ O) / Al ₂ O ₃ and the molar ratio Na ₂ O / Al ₂ O ₃ in the above range, the devitrification resistance and the deterioration coefficient (D) can be remarkably improved. .

Suitable ranges of molar ratio K ₂ O / Na ₂ O are 0.1 to 0.8, 0.2 to 0.8, 0.2 to 0.5, in particular 0.2 to 0.4. When the molar ratio K ₂ O / Na ₂ O decreases, the thickness of the compressive stress layer tends to be thin, and when the molar ratio K ₂ O / Na ₂ O increases, the compressive stress value decreases, or the glass is devitrified due to lack of component balance of the glass composition. Easier

MgO is a component that lowers the viscosity at high temperature to increase meltability and formability, or to increase distortion and Young's modulus, and is a component having an effect of increasing ion exchange performance among alkaline earth metal oxides. Therefore, content of MgO is 0.5% or more, and a suitable lower limit range is 1% or more, 1.5% or more, 2% or more, 3% or more, 5% or more, especially 6% or more. However, when there is too much content of MgO, there exists a tendency for a density and a thermal expansion coefficient to become high, and glass to devitrify easily. Therefore, content of MgO is 13% or less, and a suitable upper limit range is 12% or less, 11% or less, 9% or less, 8% or less, 7% or less, especially 6.5% or less.

The molar ratio _{MgO / (MgO + Al 2 O} 3) is likely to be decreased when the ion exchange performance, and Young's modulus decreases. In addition, the deterioration coefficient D tends to be large. The suitable lower limit of the molar ratio MgO / (MgO + Al ₂ O ₃ ) is at least 0.05, at least 0.1, at least 0.15, at least 0.2, at least 0.25, in particular at least 0.3. On the other hand, the molar ratio _{MgO / (MgO + Al 2 O} 3) is greater teeming substantial degradation, or higher density, or the coefficient of thermal expansion is excessively high. The upper limit of the molar ratio MgO / (MgO + Al ₂ O ₃ ) is preferably at most 0.95, at most 0.9, at most 0.85, at most 0.8, at most 0.7, at most 0.6, in particular at most 0.5. Further, "MgO + Al ₂ O _3" is the total amount of MgO and Al ₂ O _3.

Compared with other components, CaO has a high effect of lowering the viscosity at high temperature without accompanied by a decrease in the devitrification resistance to increase meltability and formability, or to increase distortion and Young's modulus. The content of CaO is 0 to 6%. However, when there is too much content of CaO, there exists a tendency for a density and a thermal expansion coefficient to become high, and also to lack the component balance of a glass composition, to make glass break through easily, to deteriorate ion exchange performance, or to increase a deterioration coefficient (D). Therefore, suitable content of CaO is 0 to 5%, 0 to 4%, 0 to 3.5%, 0 to 3%, 0 to 2%, especially 0 to 1%.

After regulating MgO content in the said range, it is preferable to regulate molar ratio MgO / (MgO + CaO) to 0.5 or more, 0.55 or more, 0.6 or more, 0.7 or more, 0.8 or more, especially 0.9 or more. When molar ratio MgO / (MgO + CaO) becomes small, there exists a tendency for deterioration coefficient (D) to become large and ion exchange performance tends to fall. Moreover, when MgO content is out of the said range, it becomes difficult to smell the effect by regulating molar ratio MgO / (MgO + CaO) in addition to lacking the component balance of a glass composition, and making devitrification resistance easy to fall. In addition, "MgO + CaO" is total amount of MgO and CaO.

SrO is a component that lowers the viscosity at high temperature to increase meltability and formability, or to increase distortion and Young's modulus. Content of SrO is 0 to 6%. When there is too much content of SrO, in addition to the ion exchange reaction being easy to be inhibited, a density and a thermal expansion coefficient become high, or glass becomes easy to devitrify. Suitable content of SrO is 0 to 4.5%, 0 to 3%, 0 to 2%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, in particular 0 to 0.1%.

Tempered glass according to the present embodiment is substantially free of _{As 2 O 3, Sb 2 O} 3, PbO, F, and as the glass composition from environmental consideration.

In addition to the above components, for example, the following components may be added.

BaO is a component that lowers the viscosity at high temperature to increase meltability and formability, or to increase distortion and Young's modulus. When the content of BaO is too large, the ion exchange reaction tends to be inhibited, and in addition, the density and the coefficient of thermal expansion are increased, or the glass is easily devitrified. Suitable content of BaO is 0-6%, 0-3%, 0-1.5%, 0-1%, 0-0.5%, especially 0-0.1%.

By regulating the content of SrO + BaO, the ion exchange performance can be significantly increased. Suitable contents of SrO + BaO are 0-6%, 0-3%, 0-2.5%, 0-2%, 0-1%, in particular 0-0.2%. In addition, "SrO + BaO" is total amount of SrO and BaO.

Suitable ranges of molar ratio (CaO + SrO + BaO) / MgO are 0 to 1, 0 to 0.9, 0 to 0.8, 0 to 0.75, in particular 0 to 0.5. If the molar ratio (CaO + SrO + BaO) / MgO increases, the devitrification resistance, the ion exchange performance, the deterioration coefficient (D) increases, or the density or thermal expansion coefficient becomes excessively high. In addition, "CaO + SrO + BaO" is total amount of CaO, SrO, and BaO.

The content of MgO + CaO + SrO + BaO is preferably 0.5 to 10%, 0.5 to 8%, 0.5 to 7%, 0.5 to 6%, particularly 0.5 to 4%. If the content of MgO + CaO + SrO + BaO is too small, it is difficult to increase the meltability and the moldability. On the other hand, when there is too much content of MgO + CaO + SrO + BaO, there exists a tendency for ion exchange performance to fall in addition to a high density, a thermal expansion coefficient, or a devitrification resistance. In addition, "MgO + CaO + SrO + BaO" is a total amount of MgO, CaO, SrO, and BaO.

The mass ratio (MgO + CaO + SrO + BaO) / (Li ₂ O + Na ₂ O + K ₂ O) is preferably 0.5 or less, 0.3 or less, particularly 0.2 or less. A larger mass ratio (MgO + CaO + SrO + BaO ) / (Li 2 O + Na 2 O + K 2 O) tends to be lowered substantial covered.

TiO ₂ is a component that enhances ion exchange performance and a component that lowers the high temperature viscosity, but when the content is too large, the glass is easily colored or devitrified. Therefore, the content of TiO ₂ is preferably 0 to 3%, 0 to 1%, 0 to 0.8%, and 0 to 0.5%, particularly 0 to 0.1%.

ZrO ₂ is a component that significantly increases the ion exchange performance and increases the viscosity and strain point near the liquid viscosity, but when the content is too large, the devitrification resistance may be significantly lowered, and the density may be too high. Thus, a suitable upper limit of ZrO ₂ is at most 10%, at most 8%, at most 6%, at most 4%, at most 3%, in particular at most 1%. Moreover, when it is desired to improve ion exchange performance, the suitable lower limit of ZrO ₂ is 0.01% or more, 0.1% or more, 0.5% or more, 1% or more, particularly 2% or more.

ZnO is a component that increases ion exchange performance, and is a component that is particularly effective in increasing the compressive stress value. Moreover, it is a component which reduces high temperature viscosity, without reducing low temperature viscosity. However, when there is too much content of ZnO, there exists a tendency for glass to powder-separate, devitrification resistance, high density, or the thickness of a compressive stress layer becoming thin. Therefore, the content of ZnO is preferably 0 to 6%, 0 to 5%, and 0 to 3%, particularly 0 to 1%.

P ₂ O ₅ is a component that increases ion exchange performance, and is a component that especially thickens the compressive stress layer. However, or when the content of P ₂ O ₅ is too large, the glass phase separation, the water resistance tends to be lowered. Therefore, the content of P ₂ O ₅ is preferably 0 to 10%, 0 to 3%, and 0 to 1%, particularly 0 to 0.5%.

As a refining agent CeO _2, SnO _2, Cl, a group of SO ₃ may be one or two or more selected from (preferably the group consisting of SnO _2, Cl, SO ₃₎ adding 0 to 3%. The content of SnO ₂ + SO ₃ + Cl is preferably 0 to 1%, 0.001 to 1%, 0.01 to 0.5%, particularly 0.03 to 0.2%. In addition, "SnO ₂ + SO ₃ + Cl" is the total amount of SnO ₂ , Cl, and SO ₃ .

SnO ₂ also has an effect of increasing ion exchange performance in addition to the clarification effect. For this reason, addition of SnO ₂ can simultaneously enjoy the effect of enhancing the clarification effect and the ion exchange performance. The content of SnO ₂ is preferably 0 to 3%, 0.01 to 3%, and 0.01 to 3%, particularly 0.1 to 1%. On the other hand, when SnO ₂ is added, the glass may be colored. When it is necessary to obtain a clarification effect while suppressing the coloring of the glass, it is preferable to add SO ₃ . The content of SO ₃ is 0 to 3%, particularly preferably 0.001 to 3%. In addition, when SnO ₂ and SO ₃ coexist, coloring can be suppressed while improving ion exchange performance.

The content of Fe ₂ O ₃ is preferably less than 1000 ppm (less than 0.1%), less than 800 ppm, less than 600 ppm, less than 400 ppm, especially less than 300 ppm. Moreover, after regulating the content of Fe ₂ O _{3 in} the above range, it is preferable to regulate the molar ratio Fe ₂ O ₃ / (Fe ₂ O ₃ + SnO ₂ ) to 0.8 or more, 0.9 or more, particularly 0.95 or more. In this way, the transmittance | permeability (400 nm-770 nm) of glass in 1 mm of plate | plate thickness will become easy to improve (for example, 90% or more).

Rare earth oxides such as Nb ₂ O ₅ and La ₂ O ₃ are components that increase the Young's modulus. However, when the cost of the raw material itself is high and a large amount is added, the devitrification resistance tends to decrease. Therefore, the content of the rare earth oxide is preferably 3% or less, 2% or less, 1% or less, 0.5% or less, particularly 0.1% or less.

Transition metal elements (Co, Ni, etc.) which strongly color glass may reduce the transmittance of glass. In particular, when used in a touch panel display, when the content of the transition metal element is too large, the visibility of the touch panel display tends to be lowered. Therefore, it is preferable to select a glass raw material (including a cullet) so that content of a transition metal oxide may be 0.5% or less, 0.1% or less, especially 0.05% or less.

Tempered glass according to one embodiment of the invention preferably does not substantially contain the Bi ₂ O ₃ from environmental consideration. "Substantially contains no Bi ₂ O _3" refers to actively adding Bi ₂ O ₃ as a glass component, Although not a condition that allows the case to be incorporated as an impurity, and specifically indicate that the content of Bi ₂ O ₃ is less than 0.05mol%.

In the tempered glass of this embodiment, it is possible to select an appropriate content range of each component suitably, and to make it the suitable glass composition range. Especially, the suitable glass composition range is as follows.

(1) glass composition in mol% SiO ₂ 50-75%, Al ₂ O ₃ 4-12%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 10-17%, K ₂ O 2-7%, MgO 1.5-12%, CaO 0-3%, SrO 0-1%, TiO ₂ 0-0.5%, molar ratio MgO / (MgO + CaO) is 0.5-1,

(2) glass composition in mol% SiO ₂ 50-75%, Al ₂ O ₃ 4-12%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 10-17%, K ₂ O 2-7%, MgO 1.5-12%, CaO 0-3%, SrO 0-1%, TiO ₂ 0-0.5%, molar ratio MgO / (MgO + CaO) is 0.5-1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.2 ~ 0.85, molar ratio (CaO + SrO + BaO) / MgO is 0 ~ 0.85,

(3) glass composition in mol% SiO ₂ 55-69%, Al ₂ O ₃ 4-11%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 11-16%, K ₂ O 2-7%, MgO 3-9%, CaO 0-3%, SrO 0-1%, ZrO ₂ 1-9%, TiO ₂ 0-0.1%, containing the molar ratio MgO / (MgO + CaO ) Is 0.5 to 1,

(4) glass composition in mol% SiO ₂ 55-69%, Al ₂ O ₃ 4-11%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 11-16%, K ₂ O 2-7%, MgO 3-9%, CaO 0-3%, SrO 0-1%, ZrO ₂ 1-9%, TiO ₂ 0-0.1%, containing the molar ratio MgO / (MgO + CaO ) Is 0.5 to 1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.25 to 0.8, molar ratio (CaO + SrO + BaO) / MgO is 0 to 0.75,

(5) SiO _{2 in} mol% as glass composition 58 to 67%, Al ₂ O ₃ 4 to 11%, B ₂ O ₃ 0 to 0.5%, Li ₂ O 0 to 0.5%, Na ₂ O 11 to 16%, K ₂ O 2 to 6%, MgO 3 to 6.5%, CaO 0-3%, SrO 0-0.5%, ZrO ₂ 2-6%, TiO ₂ 0-0.1%, molar ratio MgO / (MgO + CaO) is 0.5-1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.25 ~ 0.8, molar ratio (CaO + SrO + BaO) / MgO is 0 ~ 0.75,

(6) glass composition in mol% SiO ₂ 58-67%, Al ₂ O ₃ 7-11%, B ₂ O ₃ 0-0.5%, Li ₂ O 0-0.5%, Na ₂ O 11-16%, K ₂ O 2-6%, MgO 3-6.5%, CaO 0-3%, SrO 0-0.5%, ZrO ₂ 2-6%, TiO ₂ 0-0.1%, containing the molar ratio MgO / (MgO + CaO ) Is 0.5 to 1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.25 to 0.8, and molar ratio (CaO + SrO + BaO) / MgO is 0 to 0.75.

In addition, when it is desired to obtain high ion exchange performance after reducing the density, the following glass composition range is preferable.

(7) glass composition in mol% SiO ₂ 50-75%, Al ₂ O ₃ 10-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-2%, Na ₂ O 12-20%, K ₂ O 0.5-9%, MgO 3-12%, CaO 0-6%, SrO 0-6%,

(8) glass composition in mol% SiO ₂ 55-75%, Al ₂ O ₃ 10-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-2%, Na ₂ O 13-20%, K ₂ O 1-8%, MgO 6-12%, CaO 0-6%, SrO 0-6%, ZrO ₂ 0-1%, molar ratio MgO / (MgO + CaO) is 0.5-1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.1-0.9, molar ratio (CaO + SrO + BaO) / MgO is 0-0.75,

(9) glass composition in mol% SiO ₂ 55-75%, Al ₂ O ₃ 10-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-2%, Na ₂ O 13-20%, K ₂ O 1-8%, MgO 6-12%, CaO 0-6%, SrO 0-6%, ZrO ₂ 0-1%, and the molar ratio MgO / (MgO + CaO) is 0.7-1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.25-0.6, molar ratio (CaO + SrO + BaO) / MgO is 0-0.5,

(10) glass composition in mol% SiO ₂ 55-75%, Al ₂ O ₃ 10-13%, B ₂ O ₃ 0-1%, Li ₂ O 0-2%, Na ₂ O 13-20%, K ₂ O 1-8%, MgO 6-12%, CaO 0-6%, SrO 0-6%, ZrO ₂ 0-1%, and the molar ratio MgO / (MgO + CaO) is 0.7-1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.25-0.6, molar ratio (CaO + SrO + BaO) / MgO is 0-0.5,

(11) glass composition as mol% in SiO ₂ 55-70%, Al ₂ O ₃ 10-13%, B ₂ O ₃ 0-0.1%, Li ₂ O 0-0.2%, Na ₂ O 13-20%, K ₂ O 1-8%, MgO 6-12%, CaO 0-6%, SrO 0-6%, ZrO ₂ 0-1%, molar ratio MgO / (MgO + CaO) is 0.7-1, molar ratio MgO / (MgO + Al ₂ O ₃ ) is 0.25-0.6, molar ratio (CaO + SrO + BaO) / MgO is 0- 0.5.

It is preferable that the tempered glass of this embodiment has the following characteristics, for example.

The tempered glass of this embodiment has a compressive stress layer on the surface. The compressive stress value of the compressive stress layer is preferably 300 MPa or more, 400 MPa or more, 500 MPa or more, 600 MPa or more, particularly 900 MPa or more. The larger the compressive stress value, the higher the mechanical strength of the tempered glass. On the other hand, when an extremely large compressive stress is formed on the surface, micro cracks may occur on the surface, and the mechanical strength of the tempered glass may be lowered. Moreover, there exists a possibility that the tensile stress inherent in a tempered glass may become extremely high. For this reason, the compressive stress value of the compressive stress layer is preferably 2000 MPa or less. In addition, when the content of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , MgO, and ZnO in the glass composition is increased or the content of SrO and BaO is decreased, the compressive stress value tends to increase. In addition, when the ion exchange time is shortened or the temperature of the ion exchange solution is lowered, the compressive stress value tends to increase.

The thickness of the compressive stress layer is preferably 10 µm or more, 15 µm or more, 20 µm or more, 30 µm or more, particularly 40 µm or more. The thicker the compressive stress layer is, the deeper the scratches are on the tempered glass, the less likely the tempered glass is to be broken, and the less the nonuniformity in mechanical strength. On the other hand, the thicker the compressive stress layer is, the more difficult it is to cut the tempered glass. For this reason, 500 micrometers or less are preferable for the thickness of a compressive stress layer. Moreover, when the content of K ₂ O, P ₂ O _{5 in} the glass composition is increased or the content of SrO and BaO is reduced, the thickness of the compressive stress layer tends to be thick. In addition, when the ion exchange time is lengthened or the temperature of the ion exchange solution is increased, the thickness of the compressive stress layer tends to be thick.

In the tempered glass of the present embodiment, the density is preferably 2.6 g / cm 3 or less, 2.55 g / cm 3 or less, 2.50 g / cm 3 or less, particularly 2.48 g / cm 3 or less. The smaller the density, the lighter the tempered glass can be. In addition, when the content of SiO ₂ , B ₂ O ₃ , P ₂ O _{5 in} the glass composition is increased or the content of alkali metal oxide, alkaline earth metal oxide, ZnO, ZrO ₂ , TiO ₂ is reduced, the density tends to decrease. Lose.

In the tempered glass of the present embodiment, the thermal expansion coefficient in the temperature range of 30 to 380 ° C. is 80 to 120 × 10 ⁻⁷ / ° C., 85 to 110 × 10 ⁻⁷ / ° C., and 90 to 110 × 10 ⁻⁷ / C, especially 90-105x10 <^-7> / degreeC is preferable. When the coefficient of thermal expansion is regulated in the above range, it is easy to match the coefficient of thermal expansion of members such as metals and organic adhesives, and it is easy to prevent peeling of members such as metals and organic adhesives. Here, "the thermal expansion coefficient in the temperature range of 30-380 degreeC" points out the value which measured the average thermal expansion coefficient using the expansion system. In addition, when the content of the alkali metal oxide and the alkaline earth metal oxide in the glass composition is increased, the coefficient of thermal expansion tends to be increased. On the contrary, when the content of the alkali metal oxide and the alkaline earth metal oxide is reduced, the coefficient of thermal expansion tends to decrease.

In the tempered glass of the present embodiment, the strain point is preferably 500 ° C or higher, 520 ° C or higher, 530 ° C or higher, and particularly 540 ° C or higher. The higher the strain point, the higher the heat resistance and the more difficult the compressive stress layer is to be lost when the tempered glass is heat treated. In addition, the higher the strain point, the less stress relaxation occurs during the ion exchange treatment, and therefore, the compressive stress value is more easily maintained. In addition, to increase the content of alkaline earth metal oxides in the glass _{composition, Al 2 O 3, ZrO 2} , P 2 O 5 , or, if reducing the content of the alkali metal oxide tends to be raised why dots.

Temperature in 10 ^4.0 dPa · s in the glass of the present embodiment is less than 1250 ℃, 1230 ℃, 1200 ℃ or less, less than 1180 ℃, in particular less than 1160 ℃ is preferred. The lower the temperature at 10 ^4.0 dPa · s, the less the burden on the molding equipment is, the longer the life of the molding equipment is, and as a result, the manufacturing cost of the tempered glass is easier to be reduced. Increasing the content of alkali metal oxides, alkaline earth metal oxides, ZnO, B ₂ O ₃ , TiO ₂ or reducing the content of SiO ₂ , Al ₂ O ₃ tends to lower the temperature at 10 ^4.0 dPa · s. Lose.

In the tempered glass of this embodiment, the temperature in 10 ^2.5 dPa * s is 1600 degrees C or less, 1550 degrees C or less, 1530 degrees C or less, 1500 degrees C or less, Especially 1450 degrees C or less is preferable. The lower the temperature at 10 ^2.5 dPa · s, the lower temperature melting becomes possible, the burden on glass manufacturing equipment such as a melting furnace is reduced, and the bubble quality is easily increased. That is, the lower the temperature in 10 ^2.5 dPa · s, the easier the manufacturing cost of the tempered glass becomes. In addition, the temperature in 10 ^2.5 dPa * s is corresponded to melting temperature. In addition, to increase the content of free alkali metal oxides, alkaline earth metal oxide, of the composition of ZnO, B ₂ O _3, TiO _2, or, when reducing the content of SiO _2, Al ₂ O ₃ in 10 ^2.5 dPa · s The temperature is likely to decrease.

In the tempered glass of this embodiment, liquidus temperature is 1075 degrees C or less, 1050 degrees C or less, 1030 degrees C or less, 1010 degrees C or less, 1000 degrees C or less, 950 degrees C or less, 900 degrees C or less, especially 870 degrees C or less is preferable. In addition, the lower the liquidus temperature, the better the devitrification resistance and the moldability. In addition, when the content of Na ₂ O, K ₂ O, B ₂ O _{3 in} the glass composition is increased, or the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO ₂ is reduced, the liquidus temperature is increased. It becomes easy to fall.

In the tempered glass of this embodiment, liquid phase viscosity is 10 ^4.0 dPa * s or more, 10 ^4.4 dPa * s or more, 10 ^4.8 dPa * s or more, 10 ^5.0 dPa * s or more, 10 ^5.3 dPa * s or more, 10 ^5.5 dPa * s s or more, 10 ^5.7 dPa * s or more, 10 ^5.8 dPa * s or more, in particular 10 ^6.0 dPa * s or more are preferable. In addition, the higher the liquid viscosity, the better the devitrification resistance and the moldability. In addition, when the content of Na ₂ O, K ₂ O in the glass composition is increased or the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO ₂ is reduced, the liquid phase viscosity tends to increase.

In the tempered glass of the present embodiment, the Young's modulus is preferably 65 GPa or more, 69 GPa or more, 71 GPa or more, 75 GPa or more, particularly 77 GPa or more. The higher the Young's modulus, the more difficult it is to bend the tempered glass, and when used on a touch panel display or the like, even if the surface of the tempered glass is strongly pressed with a pen or the like, the amount of deformation of the tempered glass is reduced. It is easy to prevent the situation.

In the tempered glass of the present embodiment, the deterioration coefficient (D) is preferably 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, particularly 0.05 or less. The smaller the deterioration coefficient (D), the less the compressive stress value obtained even in the case of ion exchange treatment in KNO ₃ dissolved salt deteriorated with time, and as a result, it becomes easy to reduce the manufacturing cost of tempered glass.

The tempered glass sheet according to the embodiment of the present invention is characterized by being made of the tempered glass of the above embodiment. Therefore, the technical characteristics and the suitable range of the tempered glass plate of this embodiment become the same as the technical characteristics of the tempered glass of this embodiment. The description is omitted here for convenience.

In the tempered glass sheet of the present embodiment, the difference (ΔCS) of the compressive stress values of the compressive stress layers on the opposing surfaces is preferably 50 MPa or less, 30 MPa or less, 20 MPa or less, 10 MPa or less, particularly 5 MPa or less. When ΔCS increases, warpage tends to occur in the tempered glass plate after the ion exchange treatment of the large glass plate. In order to make DELTA CS into the said range, it is preferable to grind the opposing surface of a glass plate at 0.2 micrometer or more, 0.3 micrometer or more, 0.4 micrometer or more, 0.5 micrometer or more, 1 micrometer or more, 3 micrometers or more, especially 5 micrometers or more.

In the tempered glass sheet of the present embodiment, the average surface roughness Ra of the surface is preferably 10 kPa or less, 8 kPa or less, 6 kPa or less, 4 kPa or less, 3 kPa or less, particularly 2 kPa or less. The larger the average surface roughness Ra, the lower the mechanical strength of the tempered glass sheet. Here, average surface roughness Ra points out the value measured by the method based on SEMI D7-97 "the measuring method of the surface roughness of a FFP glass substrate."

In the tempered glass sheet of the present embodiment, the length is preferably 500 mm or more and 700 mm or more, particularly 1000 mm or more, and the width is preferably 500 mm or more, 700 mm or more, particularly 1000 mm or more. When the tempered glass sheet is enlarged, it can be suitably used as a cover glass of a display unit such as a large TV.

In the tempered glass sheet of the present embodiment, the plate thickness is preferably 3.0 mm or less, 2.0 mm or less, 1.5 mm or less, 1.3 mm or less, 1.1 mm or less, 1.0 mm or less, 0.8 mm or less, particularly 0.7 mm or less. On the other hand, when plate | board thickness is too thin, it will become difficult to obtain desired mechanical strength. Therefore, the plate thickness is preferably 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, particularly 0.5 mm or more.

The tempered glass according to the embodiment of the present invention is a tempered glass provided in an ion exchange treatment, which is 50% to 75% SiO ₂ , 3 to 13% Al ₂ O ₃ , B ₂ O ₃ 0 to mol% as a glass composition. 1.5%, Li ₂ O 0-4%, Na ₂ O 7-20%, K ₂ O 0.5-10%, MgO 0.5-13%, CaO 0-6%, SrO 0-4.5%, and substantially It is characterized by not containing As ₂ O ₃ , Sb ₂ O ₃ , PbO, and F. The technical characteristics of the tempered glass of this embodiment are the same as the technical characteristics of the tempered glass and the tempered glass plate of the said this embodiment. Here, the description is omitted for convenience.

Glass for strengthening according to the present embodiment if the ion-exchanged in a KNO ₃ in 430 ℃ sea salt for a compressive stress value of the compressive stress layer on the surface over 300㎫, and also preferred that the thickness of the compressive stress layer which is more than 10㎛ In addition, the compressive stress of the surface is preferably 600 MPa or more, and the thickness of the compressive stress layer is preferably 50 µm or more, and the compressive stress of the surface is 700 MPa or more, and the thickness of the compressive stress layer is 50 µm or more. desirable.

In the ion exchange treatment, the temperature of the KNO ₃ dissolved salt is preferably 360 to 550 ° C, and the ion exchange time is preferably 2 to 10 hours, particularly 4 to 8 hours. This makes it easy to form a compressive stress layer appropriately. In addition, since the tempered glass of the present embodiment has the above glass composition, the compressive stress value of the compressive stress layer can be increased or the thickness can be increased without using a mixture of KNO ₃ dissolved salts and NaNO ₃ dissolved salts. Also deteriorated KNO ₃ Even when molten salt is used, the compressive stress value and thickness of the compressive stress layer are not extremely reduced.

In the glass plate for strengthening of this embodiment, the maximum value Fmax of the residual stress in the planar direction with respect to the entire planar portion of the glass plate is preferably 5 MPa or less, 3 MPa or less, 1 MPa or less, 0.5 MPa or less, particularly 0.1 MPa or less. Do. When the maximum value Fmax of residual stress is large, the curvature of a tempered glass plate may become large when reinforcing a large glass plate.

A glass plate for reinforcement of this embodiment is preferably formed by film-forming a film of SiO _2, TiO _2, Yes.Where, such as ITO, the AR surface. In this way, the curvature of a tempered glass plate can be reduced, even without a grinding | polishing process. Examples of the film formation method include CVD, sputtering, and spin coating. When the film is formed by sputtering, the film thickness is preferably 1 nm or more, 5 nm or more, 10 nm or more, 30 nm or more, particularly 50 nm or more. On the other hand, when film thickness is too thick, there exists a possibility that the compressive stress value of the compressive stress layer in a film surface may fall too much. Therefore, a suitable upper limit of the film thickness is 1000 nm or less, 800 nm or less, 500 nm or less, especially 300 nm or less. Moreover, it is preferable to form into a film in the part which tends to bend after a strengthening process. In addition, it is preferable that the tempered glass sheet of the present embodiment is formed by forming a film of SiO ₂ , TiO ₂ , Nesa, ITO, AR, or the like onto the surface before the tempering treatment.

The tempered glass, tempered glass, and tempered glass plate of the present embodiment can be produced as follows.

First, the glass raw materials combined so as to have the above glass composition are introduced into a continuous melting furnace, heated and melted at 1500 to 1600 ° C, clarified and then supplied to a molding apparatus, and then molded into a plate shape, and cooled to form a glass such as a plate shape. I can make it.

It is preferable to employ | adopt the float method as a method of shape | molding to plate shape. The float method is a method that can produce a glass plate in a large amount at low cost, and is a method that can easily produce a large glass plate.

In addition to the float method, various molding methods can be employed. For example, molding methods such as an overflow down draw method, a down draw method (slot down method, a reed method, etc.), a roll out method, and a press method can be adopted.

Then, tempered glass can be produced by strengthening the obtained glass. The time for cutting the tempered glass to a predetermined dimension may be before the tempering treatment, but it is advantageous in terms of cost to perform the tempering glass after the tempering treatment.

Ion exchange treatment is preferred as the reinforcement treatment. The conditions of the ion exchange treatment are not particularly limited, and an optimal condition may be selected in consideration of the viscosity characteristics, the use, the thickness, the internal tensile stress, and the like of the glass. For example, the ion exchange treatment can be carried out by dipping the glass in 1-8 hours for sea salt of KNO ₃ 400 ~ 550 ℃. In particular, ion exchange of K ions in the KNO ₃ dissolved salt with the Na component in the glass enables efficient formation of a compressive stress layer on the surface of the glass.

Example 1

Hereinafter, embodiments of the present invention will be described. In addition, the following Example is a mere illustration. The present invention is not limited to the following examples at all.

Tables 1-5 show the Example (sample No. 1-24) of this invention. In addition, "me" in a table means unmeasured.

Each sample in the table was produced as follows. First, the glass raw material was combined so that it might become the glass composition in a table | surface, and it melted at 1580 degreeC for 8 hours using the platinum pot. Then, the obtained molten glass was flowed on the carbon plate, and it shape | molded in plate shape. Various characteristics were evaluated about the obtained glass plate.

Density (rho) is the value measured by the known Archimedes method.

Thermal expansion coefficient (alpha) is the value which measured the average thermal expansion coefficient in the temperature range of 30-380 degreeC using an expansion system.

Distortion point (Ps) and slow cooling point (Ta) are the values measured based on the method of ASTMC336.

The softening point (Ts) is a value measured according to the method of ASTM C338.

The temperature in high temperature viscosity 10 ^4.0 dPa * s, 10 ^3.0 dPa * s, and 10 ^2.5 dPa * s is the value measured by the platinum ball pulling-up method.

The liquidus temperature (TL) passes through a standard sieve 30 mesh (sieve opening 500 μm), puts the glass powder remaining in the 50 mesh (sieve opening 300 μm) in a platinum boat, and is maintained for 24 hours in a temperature gradient path. It is the value which measured the temperature which precipitates.

Liquid phase viscosity is the value which measured the viscosity of the glass in liquidus temperature by the platinum ball pulling-up method.

As clearly shown in Tables 1 to 5, Sample Nos. 1 to 24 have a density of 2.54 g / cm 3 or less and a thermal expansion coefficient of 87 to 107 × 10 ^-7 / ° C., which is a material of tempered glass, that is, a tempered glass. Suited. Moreover, since the liquid viscosity is 10 ^4.5 dPa * s or more, it can be shape | molded in plate shape by the float method, and since the temperature in 10 ^2.5 dPa * s is 1622 degreeC or less, productivity is high and a large quantity of glass plates can be manufactured at low cost. I think it is. In addition, although the glass composition in the surface layer of glass differs microscopically before and behind reinforcement treatment, when it sees as the whole glass, a glass composition does not differ substantially.

Then, the ion exchange treatment was carried out by immersing 6 hours in the respective After being subjected to optical polishing on both the surfaces of the sample KNO ₃ sea salt for the 440 ℃ (New KNO ₃ for sea salt). The surface of each sample was wash | cleaned after the ion exchange process. Subsequently, the compressive stress value and thickness of the compressive stress layer on the surface were calculated from the number of interference fringes observed using a surface stress gauge (FSM-6000 manufactured by Toshiba Corporation) and the spacing. The refractive index of each sample was 1.52 and the optical elastic constant was 28 [(nm / cm) / MPa] at the time of calculation.

The deterioration coefficient (D) was calculated as follows. First, 58.7 mass% of SiO ₂ , 12.8 mass% of Al ₂ O ₃ , 0.1 mass% of Li ₂ O, 14.0 mass% of Na ₂ O, 6.3 mass% of K ₂ O, 2.0 mass% of MgO, 2.0 mass% of ZO, 4.1 mass of ZrO ₂ A glass having a glass composition of% was produced. Subsequently, this glass was pulverized, the glass powder which passed the sieve opening 300 micrometers, and did not pass through the sieve opening 150 micrometers was extract | collected, and the glass powder of average particle diameter 225 micrometers was obtained. Subsequently, the glass powder was immersed in 400 ml of KNO ₃ maintained at 440 ° C. for 60 hours (the basket was shaken up and down 10 times for 24 hours) to similarly reproduce the deteriorated KNO ₃ dissolved salt. Further, Na ₂ O contained in the deteriorated KNO ₃ for sea salt produced in this condition was above 1000ppm (mol).

During a degradation KNO ₃ for sea salt produced in this condition, by six hours immersion of each sample in 440 ℃ it was subjected to ion exchange treatment. Then, the compressive stress value and the thickness of the compressive stress layer on the surface were determined in the same manner as the above method. Degradation coefficient [D = (compression stress value (new KNO ₃ dissolution salt) -compression stress value (degradation KNO ₃ dissolution salt)) / compression from the compressive stress value (new KNO ₃ dissolution salt, deteriorated KNO ₃ dissolution salt) obtained in this way Stress value (new KNO ₃ dissolved salt)] was calculated.

As clearly shown from Tables 1 to 5, the result of performing an ion exchange process with a new KNO ₃ for sea salt for sample No.1 ~ 24 the compression stress value of the compressive stress layer on the surface is at least 730㎫, thickness 43㎛ It was above. In addition, as a result of performing an ion exchange treatment with the deteriorated KNO ₃ dissolved salt, the compressive stress value of the compressive stress layer on the surface thereof was 625 MPa or more, the thickness was 43 µm or more, and the deterioration coefficient (D) was 0.22 or less.

Example 2

After combining glass raw materials so that it might become the glass composition of sample No. 1, after melting the obtained glass batch, the glass plate was shape | molded by the float method. Then, the ion exchange treatment was carried out by 6 hours immersion of the glass plate obtained in the KNO ₃ sea salt (sea salt for new KNO ₃₎ for the 440 ℃. Then, the compressive stress value and thickness of the surface compressive stress layer were computed from the number and interference | interval of the interference pattern observed using the surface stress meter (FSM-6000 by Toshiba Corporation) with respect to a glass plate. Further, after polishing both surfaces of the glass plate by 0.2 µm, the compressive stress value and thickness of the compressive stress layer on the surface were determined from the number and the intervals of interference fringes observed using a surface stress gauge (FSM-6000 manufactured by Toshiba Corporation). Calculated. Further, after polishing both surfaces of the glass plate by 10 µm, the compressive stress value and thickness of the compressive stress layer on the surface were determined from the number and the intervals of interference fringes observed using a surface stress gauge (FSM-6000 manufactured by Toshiba Corporation). Calculated. The refractive index of the glass plate was 1.52 and the optical elastic constant was 28 [(nm / cm) / MPa] at the time of calculation. As a result, in the case of unpolishing, the difference (ΔCS) of the compressive stress value between the surface (front face) and the compressive stress layer on the back surface is 40 MPa. The difference (ΔCS) of the compressive stress value was 20 MPa, and the difference (ΔCS) of the compressive stress value between the compressive stress layer on the front surface and the back surface was not seen when both surfaces were polished by 10 µm.

Example 3

Subsequently, after combining glass raw materials so that it might become the glass composition of sample No. 1, after melting the obtained glass batch, the glass plate of 1 mm of plate | board thickness was shape | molded by the float method. At that time, temperature setting was performed so that the temperature of the tin bath inlet vicinity might be 1200 degreeC, and the temperature of the outlet vicinity might be about 700 degreeC. Subsequently, the glass plate exiting the tin bath was passed through a slow cooling furnace. The temperature is set so that the temperature near the inlet of the slow cooling furnace is about 700 ° C and the temperature near the outlet is about 100 ° C, and the temperature distribution in the plate width direction is ± 2% or less, and the temperature difference between the front and rear surfaces of the glass plate in the slow cooling furnace is ± 1. Slow cooling was performed while controlling the temperature so as to be% or less. A 1m × 1m glass plate was cut out from the obtained glass plate, and a birefringent measuring device made by Uniopt Co., Ltd .: ABR-10A was used for the copper glass plate, and the residual stress value at the lattice intersection position of 10 cm pitch and near the outer peripheral part of four sides was measured. did. The data is shown in FIG. As a result, the maximum value Fmax of the residual stress in the planar direction of the glass plate was 0.25 MPa. In addition, the bending amount of the result of the ion exchange treatment by immersing the glass plate 6 hours in a KNO ₃ sea salt (sea salt for new KNO ₃₎ for the 440 ℃ reinforced glass plate was 0.1%. From this result, when the distribution of residual stress in a planar direction was regulated, it turned out that the curvature amount of a tempered glass plate can be reduced, even without a grinding | polishing process. In addition, the curvature amount of a tempered glass plate is the value which measured the straightness per long side dimension using a laser interferometer.

Example 4

Furthermore, after combining glass raw materials so that it might become the glass composition of sample No. 1, after melting the obtained glass batch, the glass plate of 1 mm of plate | board thickness was shape | molded by the float method. At that time, temperature setting was performed so that the temperature of the tin bath inlet vicinity might be 1200 degreeC, and the temperature of the outlet vicinity might be about 700 degreeC. Subsequently, the glass plate exiting the tin bath was passed through a slow cooling furnace. The temperature is set so that the temperature near the inlet of the slow cooling furnace is about 700 ° C and the temperature near the outlet is about 100 ° C, and the temperature distribution in the plate width direction is ± 2% or less, and the temperature difference between the front and rear surfaces of the glass plate in the slow cooling furnace is ± 1. Slow cooling was performed while controlling the temperature so as to be% or less. In addition, [Example 3] and [Example 4] differ in slow cooling rate. A 1m × 1m glass plate was cut out from the obtained glass plate, and a birefringent measuring device made by Uniopt Co., Ltd .: ABR-10A was used for the copper glass plate, and the residual stress value at the lattice intersection position of 10 cm pitch and near the outer peripheral part of four sides was measured. did. The data is shown in FIG. As a result, the maximum value Fmax of the residual stress in the plane direction of the glass plate was 0.80 MPa. Moreover, subjected to ion exchange treatment by immersing the glass plate 6 hours in a KNO ₃ sea salt (sea salt for new KNO ₃₎ for the 440 ℃ result, the bending amount of the reinforced glass plates was 0.1%. From this result, when the distribution of residual stress in a planar direction was regulated, it turned out that the curvature amount of a tempered glass plate can be reduced, even without a grinding | polishing process. In addition, the curvature amount of a tempered glass plate is the value which measured the straightness per long side dimension using a laser interferometer.

Here, SO ₂ from the top and the bottom near the outlet of the tin bath is prevented so that the glass out of the tin bath is not damaged by subsequent roller conveyance. It is preferable to inject gas. When the SO ₂ gas adheres to the glass, there is an effect of eluting Na in the glass. On the other hand, if a compositional imbalance occurs on the upper and lower surfaces of the glass, it may cause bending. Therefore, SO and the _second gas is constant in the upper and lower sides of the glass, it is also preferable to ensure a constant in each of the vertical width direction. Therefore, in order to supply the SO ₂ gas by forming a slit-shaped gas ejection port extending in the width direction in each of the upper and lower portions of the glass, and forming a slit-shaped gas exhaust port extending in the width direction immediately behind the gas ejection port. desirable. The flow rate of the SO ₂ gas is set to 1 liter / min, for example.

Example 5

Subsequently, after combining glass raw materials so that it might become the glass composition of sample No. 1, after melting the obtained glass batch, the glass plate of 1 mm of plate | board thickness was shape | molded by the float method. At that time, temperature setting was performed so that the temperature of the tin bath inlet vicinity might be 1200 degreeC, and the temperature of the outlet vicinity might be about 700 degreeC. Subsequently, the glass plate exiting the tin bath was passed through a slow cooling furnace. The temperature is set so that the temperature near the inlet of the cooling furnace is about 700 ° C. and the temperature near the outlet is about 100 ° C., and the temperature distribution in the plate width direction is controlled to ± 2% or less, and the temperature of the glass plate in the cooling furnace is reduced. Slow cooling was performed while temperature control so that the temperature difference between the front and back surfaces (greater than ± 2% and less than ± 10%) became large. The resulting glass plate of 440 ℃ KNO ₃ (New KNO ₃ for sea salt), the 6 hours when immersed in a reinforced glass plate topmyeon (top face) direction with hwinda convexly about 1% (direction that is not in contact with the tin bath). At that time, the compressive stress value of the compressive stress layer on the top surface side was 15 MPa higher than the bottom face (tin bath contact surface) side. In addition, the thickness of the compressive stress layer was equivalent at the top surface and the bottom surface. Thus, after the film formation on the top surface side of the SiO ₂ film 100㎚ film thickness by a sputtering method. The obtained glass sheet of 440 ℃ KNO ₃ (New KNO ₃ for sea salt), a result of 6 hours immersion in topmyeon and compressive stress value of the bottom surface The difference was about 1 MPa or less, and the curvature amount was also reduced to 0.1%.

Industrial availability

The tempered glass and tempered glass plate of the present invention are suitable as glass substrates such as cover glass such as mobile phones, digital cameras, PDAs, or touch panel displays. Further, the tempered glass and the tempered glass sheet of the present invention are those in which high mechanical strength is required in addition to these applications, for example, window glass, substrate for magnetic disk, substrate for flat panel display, cover glass for solar cell, cover glass for solid-state image sensor, Application to tableware can be expected.

Claims (24)

As a tempered glass with a compressive stress layer on its surface: SiO _{2 in} mol% as the glass composition 50-75%, Al ₂ O ₃ 3-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-4%, Na ₂ O 7-20%, K ₂ O 0.5-10%, MgO 0.5-13%, CaO 0-6%, A tempered glass containing 0 to 4.5% of SrO and substantially free of As ₂ O ₃ , Sb ₂ O ₃ , PbO, and F. ₃ . The method of claim 1,
SiO _{2 in} mol% as glass composition 50-75%, Al ₂ O ₃ 4-13%, B ₂ O ₃ 0-1.5%, Li ₂ O 0-2%, Na ₂ O 9-18%, K ₂ O 1-8%, MgO 0.5-12%, CaO 0-3.5%, SrO 0 ~ 3%, TiO ₂ Tempered glass containing 0 to 0.5%. 3. The method according to claim 1 or 2,
SiO _{2 in} mol% as glass composition 50-75%, Al ₂ O ₃ 4-12%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 10-17%, K ₂ O 2-7%, MgO 1.5-12%, CaO 0-3%, SrO 0 ~ 1%, TiO ₂ Tempered glass containing 0 to 0.5%. The method according to any one of claims 1 to 3,
Glass composition by mol% 55 to 75% mol ₂ , Al ₂ O ₃ 4-11%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 10-16%, K ₂ O 2-7%, MgO 3-12%, CaO 0-3%, SrO 0-1%, ZrO ₂ 0.5-10%, TiO ₂ 0-0.5%, The tempered glass characterized by the above-mentioned. The method according to any one of claims 1 to 4,
SiO _{2 in} mol% as glass composition 55-69%, Al ₂ O ₃ 4-11%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 11-16%, K ₂ O 2-7%, MgO 3-9%, CaO 0-3%, SrO 0-1%, ZrO ₂ 1-9%, TiO ₂ 0-0.1%, The tempered glass characterized by the above-mentioned. 6. The method according to any one of claims 1 to 5,
The compressive stress value of a compressive stress layer is 300 Mpa or more, and the thickness of a compressive stress layer is 10 micrometers or more, The tempered glass characterized by the above-mentioned. 7. The method according to any one of claims 1 to 6,
The deterioration coefficient (D) is 0.01-0.6, tempered glass characterized by the above-mentioned. The method according to any one of claims 1 to 7,
A liquidus temperature is 1075 ° C. or less, tempered glass. The method according to any one of claims 1 to 8,
The liquid phase viscosity is 10 ^4.0 dPa · s or more, tempered glass. 10. The method according to any one of claims 1 to 9,
The temperature in 10 ^4.0 dPa * s is 1250 degreeC or less, The tempered glass characterized by the above-mentioned. 11. The method according to any one of claims 1 to 10,
A tempered glass having a density of 2.6 g / cm 3 or less. 12. The method according to any one of claims 1 to 11,
Tempered glass, the Young's modulus is 65 GPa or more. It consists of the tempered glass of any one of Claims 1-12, The tempered glass plate characterized by the above-mentioned. The method of claim 13,
A tempered glass sheet formed by molding with a float method. The method according to claim 13 or 14,
A tempered glass sheet comprising a surface which is polished by 0.5 µm or more in the thickness direction. 16. The method according to any one of claims 13 to 15,
The tempered glass sheet, wherein the difference (ΔCS) of the compressive stress values of the compressive stress layers on the surfaces facing each other is 50 MPa or less. As a tempered glass sheet having a compressive stress on the surface: 500 mm or more in length, 500 mm or more in width, 0.5 to 1.5 mm in thickness, 65 kPa or more in Young's modulus, compressive stress value of 200 MPa or more, compressive stress layer The thickness of 20 micrometers or more, the deterioration coefficient (D) of 0.6 or less, and the difference (ΔCS) of the compressive stress value of the compressive stress layer of the mutually facing surface are 50 Mpa or less, The tempered glass plate characterized by the above-mentioned. 18. The method according to any one of claims 13 to 17,
Tempered glass plate, characterized in that used in the touch panel display. 18. The method according to any one of claims 13 to 17,
A tempered glass sheet, which is used for a cover glass of a mobile phone. 18. The method according to any one of claims 13 to 17,
A tempered glass sheet, which is used for a cover glass of a solar cell. 18. The method according to any one of claims 13 to 17,
A tempered glass sheet, which is used for a protective member of a display. As a tempered glass plate having a compressive stress on the surface: SiO _{2 in} mol% as the glass composition 50-75%, Al ₂ O ₃ 4-12%, B ₂ O ₃ 0-1%, Li ₂ O 0-1%, Na ₂ O 10-17%, K ₂ O 2-7%, MgO 1.5-12%, CaO 0-3%, SrO 0-1%, TiO ₂ 0-0.5%, molar ratio MgO / (MgO + CaO) 0.5 or more, length 500 mm or more, width 500 mm or more, thickness 0.5-1.5 mm, Young's modulus 65 ㎬ or more, the compressive stress value of a compressive stress layer is 400 Mpa or more, the thickness of a compressive stress layer is 30 micrometers or more, and the deterioration coefficient (D) is 0.4 or less, The tempered glass plate characterized by the above-mentioned. As a tempered glass provided for the tempering treatment: 50% to 75% SiO ₂ , 3 to 13% Al ₂ O ₃ , 0 to 1.5% B ₂ O ₃ , Li ₂ O 0 to 4%, Na as the glass composition ₂ O 7-20%, K ₂ O 0.5-10%, MgO 0.5-13%, CaO 0-6%, SrO 0-4.5%, substantially As ₂ O ₃ , Sb ₂ O ₃ , PbO, And F-free glass for tempering. A tempering glass provided in the tempering treatment, wherein the sheet thickness is 1.5 mm or less, and the maximum value Fmax of the residual stress in the planar direction with respect to the entire planar portion of the tempering glass sheet is 5 MPa or less.

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