WO2015012301A1

WO2015012301A1 - Toughened glass and glass for toughening

Info

Publication number: WO2015012301A1
Application number: PCT/JP2014/069427
Authority: WO
Inventors: 浩佑川本; 隆村田
Original assignee: 日本電気硝子株式会社
Priority date: 2013-07-24
Filing date: 2014-07-23
Publication date: 2015-01-29
Also published as: CN105102388A; TW201509853A; JP6597950B2; CN112979159A; KR102309860B1; KR20160034241A; TWI618683B; JP2015042607A

Abstract

A toughened glass having a compressive stress layer on the surface, characterized by having a glass composition which comprises, in mol%, 50 to 80% of SiO₂, 10 to 30% of Al₂O₃, 0 to 6% of B₂O_3,5 to 25% of Na₂O and 0 to 10% of MgO, and which is substantially free from As₂O₃, Sb₂O₃, PbO and F.

Description

Tempered glass and tempered glass

The present invention relates to tempered glass and glass for tempering, and particularly tempered glass and glass for tempering suitable for glass substrates for mobile phones, digital cameras, PDAs (portable terminals), solar cells, etc. About.

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

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

In recent years, the use of tempered glass for exterior parts such as digital signage, mice and smartphones has increased.

The main required properties of tempered glass include (1) high mechanical strength, (2) high scratch resistance, (3) light weight, and (4) low cost. In particular, in smartphone applications, there is an increasing demand for weight reduction, that is, thickness reduction.

JP 2006-83045 A

However, if the conventional tempered glass is made thinner, the internal tensile stress becomes excessive, and there is a possibility that fragments will be scattered when the tempered glass is broken or that the tempered glass will self-destruct. Therefore, there is a limit to increase the mechanical strength of the tempered glass by increasing the compressive stress value and thickness of the compressive stress layer. Therefore, it is effective to suppress surface damage on the tempered glass as much as possible, and to suppress a decrease in mechanical strength.

Scratches attached hard reinforced glass, as that is the cracking incidence low reinforcing glass, B ₂ O ₃ high-containing glass has been proposed. However, it is difficult to obtain high tempering characteristics with B ₂ O ₃ high content glass.

Furthermore, as the B ₂ O ₃ content increases, the strain point of the reinforcing glass tends to decrease. The low strain point tempering glass has a problem that the tempering characteristics are easily changed by the temperature change of the KNO ₃ molten salt. In particular, when the reduction in thickness is promoted, there is a problem that the amount of warpage of the tempered glass increases due to slight variations in the tempering characteristics in the tempered glass surface. In order to solve this problem, it is necessary to strictly control the tempering characteristics in the surface of the tempered glass, and in that respect, increasing the strain point of the tempered glass is effective.

Therefore, the present invention has been made in view of the above circumstances, and its technical problem is that the crack generation rate is low even when B ₂ O ₃ is not excessively contained, and the strengthening characteristics and strain points are sufficiently high. It is to create a tempered glass and a tempered glass that are high and suitable for thinning.

As a result of various studies, the present inventors have found that the above technical problem can be solved by strictly regulating the glass composition, and propose the present invention. That is, the tempered glass of the present invention is a tempered glass having a compressive stress layer on the surface, and has a glass composition of mol%, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O _3. It contains 0 to 6%, Na ₂ O 5 to 25%, MgO 0 to 10%, and is substantially free of As ₂ O ₃ , Sb ₂ O ₃ , PbO and F. Here, “substantially does not contain As ₂ O ₃ ” means that the addition of an impurity level is allowed although As ₂ O ₃ is not actively added as a glass component. Specifically, As _This refers to the case where the content of ₂ O ₃ is less than 0.1 mol%. By "substantially free of Sb ₂ O _3", but not added actively Sb ₂ O ₃ as a glass component, a purpose to allow addition of the impurity level, specifically, Sb ₂ O ₃ When the content of is less than 0.1 mol%. “Substantially no PbO” means that although PbO is not actively added as a glass component, the addition of an impurity level is allowed. Specifically, the content of PbO is 0.1 mol%. Refers to the case of less than. “Substantially no F” means that F is not actively added as a glass component, but allows the addition of an impurity level. Specifically, the content of F is 0.1 mol%. Refers to the case of less than.

The tempered glass of the present invention has a glass composition of mol%, SiO ₂ 50-80%, Al ₂ O ₃ 12-18%, B ₂ O ₃ 0-3%, Na ₂ O 12-18%, K _2. It contains 0 to 2% of O, 0.1 to 4% of MgO, and 0 to 2% of CaO, and has a molar ratio of Na ₂ O / Al ₂ O ₃ of 0.6 to 1.6.

The tempered glass of the present invention preferably has a crack generation rate of 80% or less before the tempering treatment. Here, the “crack occurrence rate” indicates a value measured as follows. First, in a constant temperature and humidity chamber maintained at a humidity of 30% and a temperature of 25 ° C., a Vickers indenter set to a load of 1000 gf is driven into the glass surface (optical polishing surface) for 15 seconds, and 15 seconds later, it is generated from the four corners of the indentation. Count the number of cracks (maximum 4 per indentation). Thus, after indenting 50 times and calculating | requiring the total number of crack generation, it calculates | requires by the formula of (total number of crack generation / 200) x100.

In the tempered glass of the present invention, it is preferable that the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, and the thickness of the compressive stress layer is 10 μm or more and 60 μm or less. Here, the “compressive stress value of the compressive stress layer” and the “thickness of the compressive stress layer” are observed when the sample is observed using a surface stress meter (for example, FSM-6000 manufactured by Toshiba Corporation). A value calculated from the number of interference fringes and their intervals.

The tempered glass of the present invention preferably has a strain point of 590 ° C. or higher. Here, “strain point” refers to a value measured based on the method of ASTM C336.

The tempered glass of the present invention preferably has a liquidus temperature of 1250 ° C. or lower. Here, “liquid phase temperature” means that after passing through a standard sieve 30 mesh (500 μm), the glass powder remaining on 50 mesh (300 μm) is put in a platinum boat and kept in a temperature gradient furnace for 24 hours, The boat is taken out and set to the highest temperature at which devitrification (crystal foreign matter) is observed inside the glass by microscopic observation.

The tempered glass of the present invention preferably has a liquidus viscosity of 10 ^4.5 dPa · s or more. Here, “liquid phase viscosity” refers to a value obtained by measuring the viscosity at the liquid phase temperature by a platinum ball pulling method.

The tempered glass of the present invention preferably has a temperature at a viscosity of 10 ^4.0 dPa · s of 1400 ° C. or lower. Here, “temperature at a viscosity of 10 ^4.0 dPa · s” refers to a value measured by a platinum ball pulling method.

When the tempered glass of the present invention is brought into contact with an alumina refractory for 48 hours at a viscosity of 10 ^4.5 dPa · s, it is preferable that the devitrification crystal generated at the contact interface is 1 piece / mm ² or less.

The tempered glass of the present invention preferably has a flat plate shape.

The tempered glass of the present invention preferably has a thickness of 0.3 to 2.0 mm.

The tempered glass of the present invention is preferably formed by an overflow down draw method. Here, the “overflow down draw method” is a method in which the molten glass overflows from both sides of the molded refractory, and the molten glass overflows and joins at the lower end of the molded refractory, and is stretched downward to form a glass plate. It is a manufacturing method. In the overflow down draw method, the surface to be the surface of the glass plate is not in contact with the surface of the molded refractory, and is molded in a free surface state. For this reason, the glass plate which is unpolished and has a good surface quality can be manufactured at low cost.

The tempered glass of the present invention is preferably used for a touch panel display.

The tempered glass of the present invention is preferably used for a cover glass of a mobile phone.

The tempered glass of the present invention is preferably used for a cover glass of a solar cell.

The tempered glass of the present invention is preferably used as a protective member for a display.

The tempered glass of the present invention has a glass composition of mol%, SiO ₂ 50-80%, Al ₂ O ₃ 12-18%, B ₂ O ₃ 0-3%, Na ₂ O 12-18%, K _2. O 2-2%, MgO 0.1-4%, CaO 0-2%, molar ratio Na ₂ O / Al ₂ O ₃ is 0.6-1.6, substantially As ₂ O ₃ , Sb ₂ O ₃ , PbO and F are not contained, the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, the thickness of the compressive stress layer is 10 μm or more and 60 μm or less, When the point is 590 ° C. or higher, the liquid phase temperature is 1250 ° C. or lower, the liquid phase viscosity is 10 ^4.5 dPa · s or higher, and the alumina refractory is contacted at a viscosity of 10 ^4.5 dPa · s for 48 hours. The devitrification crystal generated at the contact interface is 1 piece / mm ² or less, and the thickness is 0.3 to 2.0. It is mm and is flat plate shape.

The glass for strengthening of the present invention has a glass composition of mol%, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-6%, Na ₂ O 5-25%, MgO It is characterized by containing 0 to 10% and substantially not containing As ₂ O ₃ , Sb ₂ O ₃ , PbO and F.

The glass for strengthening of the present invention preferably has a crack generation rate of 80% or less.

The tempered glass of the present invention has a thickness of 0.3 to 2.0 mm, the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, and the thickness of the compressive stress layer is 10 μm or more and 60 μm or less. The strain point is 590 ° C. or more, and the crack generation rate is 80% or less.

The glass for strengthening of the present invention has a thickness of 0.7 to 2.0 mm, a compressive stress value of the compressive stress layer of 1000 MPa or more, a thickness of the compressive stress layer of 40 μm or more, and a strain point of 590 ° C. or more. The crack occurrence rate is 80% or less.

The tempered glass of the present invention preferably has a ΔCS of 100 MPa or less. Here, “ΔCS” is a compressive stress value CS ₄₀₀ when immersed in KNO ₃ molten salt at 400 ° C. for 4 hours and a compressive stress value CS ₄₃₀ when immersed in KNO ₃ molten salt at 430 ° C. for 4 hours. And the value calculated by the equation: ΔCS = CS ₄₀₀ −CS ₄₃₀ .

The tempered glass of the present invention has a compressive stress layer on its surface. As a method for forming a compressive stress layer on the surface, there are a physical strengthening method and a chemical strengthening method. The tempered glass of the present invention is preferably made by a chemical tempering method. The chemical strengthening method is a method in which alkali ions having a large ion radius are introduced into the surface of glass by ion exchange treatment at a temperature below the strain point of the glass. If the compressive stress layer is formed by the chemical strengthening method, even if the glass is thin, the compressive stress layer can be properly formed. The tempered glass does not break easily like the physical tempering method.

In the tempered glass of the present invention, the reason why the content range of each component is limited is shown below. In addition, in description of the containing range of each component,% display points out mol%, unless there is particular notice.

SiO ₂ is a component that forms a network of glass. The content of SiO ₂ is preferably 50 to 80%, 55 to 76%, 56 to 75%, 57 to 73%, 58 to 72% or 59 to 71%, particularly preferably 60 to 70%. When the content of SiO ₂ is too small, vitrification becomes difficult, and the thermal expansion coefficient becomes too high, and the thermal shock resistance tends to be lowered. On the other hand, if the content of SiO ₂ is too large, the meltability and moldability tend to be lowered, and the thermal expansion coefficient becomes too low, making it difficult to match the thermal expansion coefficient of the surrounding materials.

Al ₂ O ₃ is a component that increases ion exchange performance, strain point, and Young's modulus, and is a component that decreases the crack generation rate. The content of Al ₂ O ₃ is 10 to 30%. When the content of Al ₂ O ₃ is too small, resulting is a possibility which can not be sufficiently exhibited ion exchange performance. If the content of Al ₂ O ₃ is too small, there is a fear that the crack occurrence rate becomes higher. Therefore, the preferred lower limit range of Al ₂ O ₃ is 10% or more, 10.5% or more, 11% or more, 11.5% or more, 12% or more, 12.5% or more, 13% or more, 14% or more, It is 14.5% or more, 15% or more, 15.5% or more, 16.0% or more, or 16.1% or more, particularly 16.3% or more. On the other hand, if the content of Al ₂ O ₃ is too large, devitrified crystals are likely to precipitate on the glass, making it difficult to form a glass plate by the overflow downdraw method or the like. When a glass plate is formed by the overflow down draw method, spinel devitrification crystals are likely to precipitate at the interface with the alumina refractory. Further, if the content of Al ₂ O ₃ is too large, the thermal expansion coefficient becomes too low, making it difficult to match the thermal expansion coefficient of the surrounding material, and also reducing the acid resistance, making it difficult to apply to the acid treatment step. Further, the high-temperature viscosity becomes high, and the meltability tends to be lowered. Therefore, the preferable upper limit range of Al ₂ O ₃ is 25% or less, 20% or less, 19% or less, 18.5% or less, 18% or less, or 17.5% or less, particularly 17% 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. B ₂ O ₃ is a component that lowers the crack generation rate and improves scratch resistance. However, if the content of B ₂ O ₃ is too large, it becomes difficult to obtain high strengthening properties, the thickness of the compressive stress layer becomes particularly small, and coloring of the glass surface called burnt occurs due to ion exchange. Or water resistance tends to decrease. Therefore, the preferred range of B ₂ O ₃ is 0-6%, 0-5%, 0-4%, 0-3.5%, 0-3%, 0-2.5%, 0-2%, 0 to 1.5% or 0 to 1%, especially 0 to less than 1%.

Na ₂ O is an ion exchange component, and is a component that lowers the high temperature viscosity and improves the meltability and moldability. Na ₂ O is also a component for improving devitrification resistance and reaction devitrification with a molded body refractory, particularly alumina refractory. When Na ₂ O content is too small, or reduced meltability, lowered coefficient of thermal expansion tends to decrease the ion exchange performance. Therefore, a preferable lower limit range of Na ₂ O is 5% or more, 7% or more, more than 7%, 8% or more, 9% or more, 10% or more, or 11% or more, particularly 12% or more. On the other hand, when the content of Na ₂ O is too large, the thermal expansion coefficient becomes too high, the thermal shock resistance is lowered, and it becomes difficult to match the thermal expansion coefficient of the surrounding materials. Further, when the content of Na ₂ O is too large, or too low the strain point lacks component balance of the glass composition, rather devitrification resistance may decrease. Therefore, the preferable upper limit range of Na ₂ O is 25% or less, 23% or less, 21% or less, 20% or less, 19.5% or less, 19% or less, 18.5% or less, 18.2% or less, 18 % Or less or 17.5% or less, particularly 17% or less.

If the molar ratio Na ₂ O / Al ₂ O ₃ is too small, the meltability is lowered, the devitrification resistance is lowered, or the reaction devitrification property with the molded body refractory, particularly the alumina refractory is lowered. Further, the component balance of the glass composition is lacking, and the ion exchange performance is likely to be lowered. Therefore, the preferable lower limit range of the molar ratio Na ₂ O / Al ₂ O ₃ is 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 0.95 or more, or 0. 98 or more, especially 1.00 or more. On the other hand, if the molar ratio Na ₂ O / Al ₂ O ₃ is too large, the ion exchange performance may be lowered or the crack generation rate may be increased. Therefore, the preferable upper limit range of the molar ratio Na ₂ O / Al ₂ O ₃ is 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1. 4 or less, 1.3 or less, 1.2 or less, 1.18 or less, 1.15 or less or 1.13 or less, particularly 1.1 or less.

A suitable content of B ₂ O ₃ + Na ₂ O—Al ₂ O ₃ is −1.7 to 2.7%, 0 to 2.55% or 0.5 to 2.4%, in particular 0.8 to 2.2%. In this way, it becomes easy to optimize the meltability, strain point, ion exchange performance and crack generation rate. “B ₂ O ₃ + Na ₂ O—Al ₂ O ₃ ” is obtained by subtracting the content of Al ₂ O ₃ from the total amount of B ₂ O ₃ and Na ₂ O.

K ₂ O is a component that promotes ion exchange, and is a component that tends to increase the thickness of the compressive stress layer among alkali metal oxides. K ₂ O is a component that lowers the high-temperature viscosity to improve the meltability and moldability, and further improves the devitrification resistance. However, if the content of K ₂ O is too large, the thermal expansion coefficient becomes too high, and the thermal shock resistance is lowered or it is difficult to match the thermal expansion coefficient of the surrounding materials. If the content of K ₂ O is too large, or the strain point excessively lowers, lacking component balance of the glass composition, rather devitrification resistance tends to decrease. Therefore, the preferable upper limit range of K ₂ O is 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, particularly 2% or less. Is less than. Incidentally, when adding K ₂ O, the preferred amount is 0.1% or more, 0.5% or more, more than 1% or 1.5% or more, particularly 2% or more. When the addition of K ₂ O is avoided as much as possible, the preferred content of K ₂ O is 0 to 1% or 0 to less than 1%, particularly 0 to 0.05%.

MgO is a component that lowers the viscosity at high temperature, increases meltability and moldability, and increases the strain point and Young's modulus. Among alkaline earth metal oxides, MgO is a component that has a large effect of improving ion exchange performance. is there. Therefore, the preferable lower limit range of MgO is 0% or more, 0.1% or more, 0.5% or more, 1% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, or 3 .5% or more, particularly 3.7% or more. However, if the content of MgO is too large, the density and thermal expansion coefficient tend to be high, and the glass tends to be devitrified. In particular, when an alumina refractory is used as a molded product refractory, an overflow down draw When a glass plate is formed by this method, spinel devitrification crystals are likely to precipitate at the interface with the alumina refractory. Therefore, a preferable upper limit range of MgO is 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less, particularly 4% or less.

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

Li ₂ O is an ion exchange component, and is a component that lowers the high-temperature viscosity to increase the meltability and moldability, and also increases the Young's modulus. Furthermore, Li ₂ O generally has a large effect of increasing the compressive stress value among alkali metal oxides, but in a glass system containing 7% or more of Na ₂ O, the content of Li ₂ O is extremely large. If it becomes, there exists a tendency for a compressive stress value to fall rather. In addition, when the content of Li ₂ O is too large, in addition to the liquid phase viscosity being reduced and the glass being easily devitrified, the thermal expansion coefficient is too high, and the thermal shock resistance is reduced, It becomes difficult to match the thermal expansion coefficient of the surrounding material. Furthermore, if the content of Li ₂ O is too large, the low-temperature viscosity is excessively decreased, stress relaxation is likely to occur, and the compressive stress value may be decreased. Meanwhile, hard reinforcing glass scratched, i.e. as glass for a low reinforcing crack occurrence rate, Li ₂ O-rich glass has been proposed. However, with KNO ₃ molten salt, the ion exchange treatment the Li ₂ O-rich glass, Li ions are easily mixed in KNO ₃ molten salt. When KNO ₃ molten salt mixed with Li ions is used, there arises a problem that the strengthening characteristics of the strengthening glass become insufficient. Therefore, the preferred content of Li ₂ O is 0-2%, 0-1.7%, 0-1.5%, 0-1%, 0-1%, 0-0.5%, 0- 0.3% or 0 to 0.1%, in particular 0 to 0.05%.

CaO is a component that has a large effect of reducing melt viscosity and moldability, and increasing the strain point and Young's modulus by reducing high temperature viscosity without lowering devitrification resistance compared to other components. is there. However, if the content of CaO is too large, the density and thermal expansion coefficient become high, the balance of the components of the glass composition is lacking, and the devitrification resistance tends to be lowered, the ion exchange performance is lowered, There is a tendency to easily deteriorate the exchange solution. Therefore, the preferred content of CaO is 0-6%, 0-5%, 0-4%, 0-3.5%, 0-3%, 0-2% or 0-1%, especially 0-0. .5%.

SrO is a component that lowers the viscosity at high temperature to increase meltability and moldability, and increases the strain point and Young's modulus. However, if its content is too large, the ion exchange reaction tends to be inhibited. As a result, the density and the coefficient of thermal expansion increase, and the glass tends to devitrify. Therefore, the preferred content of SrO is 0-2%, 0-1.5%, 0-1%, 0-0.5% or 0-0.1%, especially 0-0.1%. .

BaO is a component that lowers the high-temperature viscosity to increase meltability and moldability, and increases the strain point and Young's modulus. However, when there is too much content of BaO, an ion exchange reaction will become easy to be inhibited, and also a density and a thermal expansion coefficient will become high, or glass will become devitrified easily. Therefore, the preferred content of BaO is 0-6%, 0-3%, 0-1.5%, 0-1%, 0-0.5% or 0-0.1%, especially 0-0. Less than 1%.

ZnO is a component that enhances ion exchange performance, and is a component that is particularly effective in increasing the compressive stress value. ZnO is a component that lowers the high temperature viscosity without lowering the low temperature viscosity. However, when the content of ZnO is too large, the glass tends to undergo phase separation, the devitrification resistance decreases, the density increases, or the thickness of the compressive stress layer decreases. Therefore, the preferred content of ZnO is 0-6%, 0-5% or 0-3%, especially 0-1%.

The preferred content of B ₂ O ₃ + MgO + ZnO is 0.03 to 3.94%, 0.1 to 3.8%, 0.5 to 3.7% or 1 to 3.5%, in particular 2 to 3. 4%. In this way, it becomes easy to optimize the meltability, devitrification resistance and the thickness of the compressive stress layer. “B ₂ O ₃ + MgO + ZnO” is the total amount of B ₂ O ₃ , MgO and ZnO.

TiO ₂ is a component that enhances ion exchange performance and a component that lowers the high-temperature viscosity. However, if its content is too large, the glass tends to be colored or devitrified. Therefore, the content of TiO ₂ is preferably 0 to 4.5%, 0 to less than 1% or 0 to 0.5%, particularly preferably 0 to 0.3%.

ZrO ₂ is a component that remarkably improves the ion exchange performance and a component that increases the viscosity and strain point in the vicinity of the liquid phase viscosity. However, if its content is too large, the devitrification resistance may be significantly reduced. There is also a possibility that the density becomes too high. Therefore, the preferred content of ZrO ₂ is 0 to 5%, 0 to 4% or 0 to 3%, particularly 0.001 to 2%.

SnO ₂ is a component that enhances the ion exchange performance, but if its content is too large, devitrification resistance tends to decrease. Therefore, the preferred content of SnO ₂ is 0-3%, 0.01-3%, 0.05-3% or 0.1-3%, especially 0.2-3%.

P ₂ O ₅ is a component that enhances ion exchange performance, and in particular, a component that increases the thickness of the compressive stress layer. However, when the content of P ₂ O ₅ is too large, or glass phase separation, the water resistance tends to decrease. Accordingly, the preferable content of P ₂ O ₅ is 0 to 10%, 0 to 3% or 0 to 1%, particularly 0 to 0.5%.

As a clarifier, one or two or more selected from the group of Cl, SO ₃ and CeO ₂ (preferably the group of Cl and SO ₃ ) may be added in an amount of 0 to 3%.

From the viewpoint of simultaneously enjoying the clarification effect and the effect of improving the ion exchange performance, the preferred content of SnO ₂ + SO ₃ + Cl is 0.01 to 3%, 0.05 to 3% or 0.1 to 3%, particularly 0 .2 to 3%. “SnO ₂ + SO ₃ + Cl” is the total amount of SnO ₂ , Cl and SO ₃ .

A suitable content of Fe ₂ O ₃ is less than 1000 ppm (less than 0.1%), less than 800 ppm, less than 600 ppm or less than 400 ppm, in particular less than 300 ppm. Further, the Fe ₂ O ₃ content is regulated within the above range, and the molar ratio Fe ₂ O ₃ / (Fe ₂ O ₃ + SnO ₂ ) is set to 0.8 or more or 0.9 or more, particularly 0.95 or more. It is preferable to regulate. In this way, the transmittance (400 to 770 nm) at a plate thickness of 1 mm is easily improved (for example, 90% or more).

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

The tempered glass of the present invention preferably contains substantially no As ₂ O ₃ , Sb ₂ O ₃ , PbO, and F as a glass composition from the environmental consideration. Moreover, environmental considerations, it is also preferable to contain substantially no Bi ₂ O _3. “Substantially no Bi ₂ O ₃ ” means that the addition of an impurity level is allowed, although Bi ₂ O ₃ is not actively added as a glass component. Specifically, Bi ₂ O ₃ When the content of is less than 0.05%.

In the tempered glass of the present invention, it is possible to appropriately select a suitable content range of each component to obtain a suitable glass composition range. Among them, particularly preferable glass composition ranges are as follows.
(1) As a glass composition, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-6%, Na ₂ O 5-25%, MgO 0-10% in mol%. Contains substantially no As ₂ O ₃ , Sb ₂ O ₃ , PbO and F.
(2) As a glass composition, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-6%, Na ₂ O 5-25%, MgO 0-10% in mol%. It contains 0 to 5% of CaO and substantially does not contain As ₂ O ₃ , Sb ₂ O ₃ , PbO and F.
(3) As a glass composition, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-6%, Na ₂ O 5-25%, K ₂ O 0-10 in mol%. %, MgO 0 to 10%, CaO 0 to 5%, and substantially free of As ₂ O ₃ , Sb ₂ O ₃ , PbO and F.
(4) As a glass composition, mol%, SiO ₂ 50-80%, Al ₂ O ₃ 12-18%, B ₂ O ₃ 0-3%, Na ₂ O 12-18%, K ₂ O 0-2 %, MgO 0.1 to 4%, CaO 0 to 2%, and substantially free of As ₂ O ₃ , Sb ₂ O ₃ , PbO and F.
(5) As a glass composition, SiO ₂ 50-80%, Al ₂ O ₃ 12-18%, B ₂ O ₃ 0-3%, Na ₂ O 12-18%, K ₂ O 0-8 in mol%. %, MgO 0.1-4%, CaO 0-2%, and the molar ratio Na ₂ O / Al ₂ O ₃ is 0.6-1.6, substantially As ₂ O ₃ , Sb ₂ O ₃ , PbO and F are not contained.

For example, the tempered glass of the present invention preferably has the following characteristics.

The tempered glass of the present invention 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, 700 MPa or more, 800 MPa or more, 900 MPa or more, 950 MPa or more, 1000 MPa or more, 1100 MPa or more, 1150 MPa or more, 1200 MPa or more, 1250 MPa or more or 1300 MPa or more, particularly preferably 1350 MPa or more. The greater 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, the tensile stress inherent in the tempered glass becomes extremely high, and the dimensional change before and after the tempering process may increase. For this reason, the compressive stress value of the compressive stress layer is preferably 1500 MPa or less or 1450 MPa or less, and particularly preferably 1400 MPa or less. If the content of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , MgO, ZnO in the glass composition is increased or the content of SrO, BaO is decreased, the compressive stress value tends to increase. Further, if 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, 25 μm or more, 30 μm or more, 35 μm or more, or 40 μm or more, and particularly preferably 45 μm or more. As the thickness of the compressive stress layer increases, the tempered glass is less likely to break even if the tempered glass is deeply damaged, and the variation in mechanical strength is reduced. On the other hand, the larger the compressive stress layer is, the more difficult it is to cut the tempered glass. Further, the tensile stress inherent in the tempered glass becomes extremely high, and there is a possibility that the dimensional change becomes large before and after the tempering treatment. For this reason, the thickness of the compressive stress layer is preferably 80 μm or less or 70 μm or less, particularly preferably 60 μm or less. Note that if the content of K ₂ O or P ₂ O _{5 in} the glass composition is increased or the content of SrO or BaO is decreased, the thickness of the compressive stress layer tends to increase. Moreover, if 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 increase.

The internal tensile stress value is preferably 150 MPa or less, 140 MPa or less, 130 MPa or less, 120 MPa or less, 110 MPa or less, 100 MPa or less, 90 MPa or less or 80 MPa or less, particularly preferably 70 MPa or less. If the internal tensile stress value is too high, the tempered glass tends to self-break due to physical collision or the like. On the other hand, if the internal tensile stress value is too low, it is difficult to ensure the mechanical strength of the tempered glass. The internal tensile stress value is preferably 1 MPa or more, 5 MPa or more, or 7 MPa or more, and particularly preferably 10 MPa or more. The internal tensile stress can be calculated by the following formula 1.

[Formula 1]
CT = (CS × DOL) / [t−2 × DOL]
[CT: Internal tensile stress (MPa)]
[CS: Compressive stress value of compressive stress layer (MPa)]
[DOL: thickness of compressive stress layer (μm)]
[T: Thickness (μm)]

Density is preferably 2.6 g / cm ³ or less, 2.55 g / cm ³ or less, 2.50 g / cm ³ or less, 2.48 g / cm ³ or less, or 2.46 g / cm ³ or less, particularly preferably 2. 45 g / cm ³ or less. The smaller the density, the lighter the tempered glass. In addition, 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 decreased. As a result, the density tends to decrease.

The strain point is preferably 550 ° C or higher, 580 ° C or higher, 590 ° C or higher, 600 ° C or higher, 610 ° C or higher, 615 ° C or higher, 620 ° C or higher, 625 ° C or higher, 630 ° C or higher, 640 ° C or higher, or 650 ° C or higher. Especially preferably, it is 660 degreeC or more. The higher the strain point, the harder the change in strengthening characteristics due to the temperature change of the KNO ₃ molten salt. In particular, even if the thickness is reduced, it is easy to strictly control the in-plane reinforcing characteristics. In addition, if the content of B ₂ O ₃ and the alkali metal oxide in the glass composition is increased, the strain point tends to be lowered, and conversely, if the content of SiO ₂ and Al ₂ O ₃ is increased, the strain point is reduced. It becomes easy to rise.

The temperature at a viscosity of 10 ^4.0 dPa · s is preferably 1400 ° C. or lower. The lower the temperature at a viscosity of 10 ^4.0 dPa · s, the less the burden on the forming equipment, the longer the life of the forming equipment, and the easier it is to reduce the manufacturing cost of tempered glass. If the content of alkali metal oxide, alkaline earth metal oxide, ZnO, B ₂ O ₃ , TiO ₂ is increased or the content of SiO ₂ , Al ₂ O ₃ is decreased, 10 ^4.0 dPa · s The temperature in viscosity tends to decrease.

The temperature at a viscosity of 10 ^2.5 dPa · s is preferably 1700 ° C. or lower, 1680 ° C. or lower or 1650 ° C. or lower, particularly preferably 1600 ° C. or lower. The lower the temperature at a viscosity of 10 ^2.5 dPa · s, the lower the temperature melting becomes possible, and the burden on glass manufacturing equipment such as a melting kiln is reduced and the bubble quality is easily improved. That is, the lower the temperature at a viscosity of 10 ^2.5 dPa · s, the easier it is to reduce the manufacturing cost of tempered glass. Here, the “temperature at a viscosity of 10 ^2.5 dPa · s” can be measured by, for example, a platinum ball pulling method. The temperature at a viscosity of 10 ^2.5 dPa · s corresponds to the melting temperature. Further, if the content of alkali metal oxide, alkaline earth metal oxide, ZnO, B ₂ O ₃ , TiO _{2 in} the glass composition is increased or the content of SiO ₂ , Al ₂ O ₃ is decreased, The temperature at a viscosity of 10 ^2.5 dPa · s tends to decrease.

The thermal expansion coefficient is preferably 50 to 100 × 10 ⁻⁷ / ° C., 70 to 100 × 10 ⁻⁷ / ° C. or 75 to 95 × 10 ⁻⁷ / ° C., particularly preferably 80 to 90 × 10 ⁻⁷ / ° C. is there. If the thermal expansion coefficient is regulated within the above range, the glass is less likely to be damaged by thermal shock, so that the time required for preheating before the tempering treatment and cooling after the tempering treatment can be shortened. As a result, the manufacturing cost of tempered glass can be reduced. Further, if the thermal expansion coefficient is regulated within the above range, it becomes easy to match the thermal expansion coefficient of the peripheral member such as a metal or an organic adhesive, and peeling of the peripheral member can be prevented. Increasing the content of alkali metal oxides and alkaline earth metal oxides in the glass composition increases the thermal expansion coefficient, conversely reducing the content of alkali metal oxides and alkaline earth metal oxides. If it does, a thermal expansion coefficient will become low. Here, “thermal expansion coefficient” refers to a value obtained by measuring an average thermal expansion coefficient in a temperature range of 25 to 380 ° C. using a dilatometer.

The liquidus temperature is preferably 1300 ° C. or lower, 1280 ° C. or lower, 1250 ° C. or lower, or 1230 ° C. or lower, particularly preferably 1200 ° C. or lower. In addition, devitrification resistance and a moldability improve, so that liquidus temperature is low. Also, increase the content of Na ₂ O, K ₂ O, B ₂ O _{3 in} the glass composition or decrease the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO _2. In this case, the liquidus temperature tends to decrease.

The liquid phase viscosity is preferably 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 or more, 10 ^{It is 5.7} dPa · s or more or 10 ^5.8 dPa · s or more, particularly preferably 10 ^6.0 dPa · s or more. In addition, devitrification resistance and a moldability improve, so that liquid phase viscosity is high. Moreover, if 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 decreased, the liquidus viscosity Tends to be high.

The Young's modulus is preferably 65 GPa or more, 69 GPa or more, 71 GPa or more, or 75 GPa or more, and particularly preferably 77 GPa or more. The higher the Young's modulus, the harder the tempered glass bends. When used for 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 deformation amount of the tempered glass becomes smaller. As a result, it becomes easy to prevent the tempered glass from coming into contact with the liquid crystal element located on the back surface and causing a display defect. In addition, the higher the Young's modulus, the smaller the amount of deformation with respect to the stress generated during the strengthening process, so that the dimensional change before and after the strengthening process can be reduced.

The crack occurrence rate before the tempering treatment, that is, the crack occurrence rate of the reinforcing glass is preferably 99% or less, 98% or less, 95% or less, 90% or less, 85% or less, 80% or less, 70% or less, 60%. Hereinafter, it is 50% or less or 40% or less, particularly preferably 30% or less. The lower the crack occurrence rate, the harder the surface of the tempered glass is, so that the mechanical strength of the tempered glass is less likely to decrease and the mechanical strength is less likely to vary.

The devitrification crystal generated at the contact interface when contacted with an alumina refractory with a viscosity of 10 ^4.5 dPa · s for 48 hours is preferably 1 piece / mm ² or less, 0.1 piece / mm ² or less, 0.01 piece / Mm ² or less or 0.001 piece / mm ² or less, particularly preferably 0.0001 piece / mm ² or less. In this way, when an alumina refractory is used as the molded refractory and a glass plate is formed by the overflow downdraw method, the glass is less likely to devitrify at the refractory interface, and mass production becomes possible.

The tempered glass of the present invention preferably has a flat plate shape. If it does in this way, it becomes easy to apply to the glass substrate of a mobile phone, a digital camera, PDA (portable terminal), a solar cell cover glass, or a display, especially a touch panel display. In addition, in order to improve the designability, the shape which has a bending part and / or a curved part may be sufficient as the tempered glass of this invention. Such a shape can be formed by applying heat to the glass and deforming it, and can also be formed by pouring molten glass into a mold and pressing it as necessary.

In the tempered glass of the present invention, the thickness (in the case of a flat plate shape) is preferably 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, or 0.8 mm or less. Especially preferably, it is 0.7 mm or less. On the other hand, if the thickness is too thin, it is difficult to obtain a desired mechanical strength. Therefore, the thickness is preferably 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, or 0.4 mm or more, and particularly preferably 0.5 mm or more.

Since the tempered glass of the present invention has small in-plane variation in tempering characteristics, various functional films can be suitably formed on the surface. As a functional film, for example, a transparent conductive film for imparting conductivity, an antireflection film for reducing reflectance, and an antiglare function are imparted to enhance visibility or improve writing quality with a touch pen or the like. An anti-glare film for preventing adhesion of fingerprints and an antifouling film for imparting water repellency and oil repellency are preferred. The transparent conductive film functions as an electrode for a touch sensor, and is preferably formed on the surface to be the display device side, for example. As the transparent conductive film, for example, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), or the like is used. In particular, ITO is preferable because of its low electric resistance. ITO can be formed by, for example, a sputtering method. Further, FTO and ATO can be formed by a CVD (Chemical Vapor Deposition) method. The antireflection film is formed on the surface to be the viewer side. Moreover, when there exists a space | gap between a touchscreen and tempered glass (cover glass), it is preferable to form an anti-reflective film also on the surface which should become the back surface side (the side opposite to the display device side) of tempered glass. The antireflection film is preferably, for example, a dielectric multilayer film in which a low refractive index layer having a relatively low refractive index and a high refractive index layer having a relatively high refractive index are alternately laminated. The antireflection film can be formed by, for example, a sputtering method, a CVD method, or the like. The antiglare film is formed on the surface to be the observer side when using tempered glass as a cover glass. The antiglare film preferably has an uneven structure. The uneven structure may be an island structure that partially covers the surface of the tempered glass. Moreover, it is preferable that the concavo-convex structure does not have regularity. Thereby, an anti-glare function can be enhanced. The antiglare film can be formed, for example, by applying a light-transmitting material such as SiO ₂ by a spray method and drying it. When the tempered glass is used as a cover glass, the antifouling film is formed on the surface to be the observer side. The antifouling film preferably contains a fluoropolymer containing silicon in the main chain. As the fluorine-containing polymer, a polymer having a —O—Si—O— unit in the main chain and a water-repellent functional group containing fluorine in the side chain is preferable. The fluorine-containing polymer can be synthesized, for example, by dehydrating condensation of silanol. When forming an antireflection film and an antifouling film, it is preferable to form an antifouling film on the antireflection film. Furthermore, when forming an anti-glare film, it is preferable to first form an anti-glare film and then form an antireflection film and / or an antifouling film thereon.

In the tempered glass of the present invention, it is possible to obtain a suitable tempered glass by appropriately selecting a suitable content range and suitable characteristics of each component. Among them, particularly preferable tempered glass is as follows.
(1) As a glass composition, mol%, SiO ₂ 50 to 80%, Al ₂ O ₃ 12 to 19%, B ₂ O ₃ 0 to 3%, Na ₂ O 12 to 19%, K ₂ O 0 to 8 %, MgO 0.1 to 3%, CaO 0 to 2%, the molar ratio Na ₂ O / Al ₂ O ₃ is 0.6 to 1.6, substantially As ₂ O ₃ , Sb ₂ O ₃ , PbO and F are not contained, the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, the thickness of the compressive stress layer is 10 μm or more and 60 μm or less, and the strain point is 620 ° C. When the liquid phase temperature is 1250 ° C. or lower, the liquid phase viscosity is 10 ^4.5 dPa · s or higher, and the alumina refractory is contacted at a viscosity of 10 ^4.5 dPa · s for 48 hours, it is generated at the contact interface. Devitrified crystal is 1 piece / mm ² or less, thickness is 0.3 to 2.0 mm, flat plate Shape.

The glass for strengthening of the present invention has a glass composition of mol%, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-6%, Na ₂ O 5-25%, MgO It contains 0 to 10% and substantially does not contain As ₂ O ₃ , Sb ₂ O ₃ , PbO and F. Therefore, the technical characteristics (preferable characteristics, preferable component ranges, etc.) of the tempered glass of the present invention overlap with the technical characteristics of the tempered glass of the present invention. It is described in the column. Therefore, detailed description of the overlapping portion is omitted.

In the tempered glass of the present invention, ΔCS is preferably 100 MPa or less, 80 MPa or less or 60 MPa or less, particularly preferably 40 MPa or less. In this way, the variation in the strengthening characteristics due to the variation in the strengthening temperature is reduced, and the warpage during the strengthening process can be suppressed to a small level.

When the glass for strengthening of the present invention is immersed in KNO ₃ molten salt at 430 ° C. for 4 hours, the compressive stress value of the compressive stress layer on the surface is 300 MPa or more, 400 MPa or more, 500 MPa or more, 600 MPa or more, 700 MPa or more, 800 MPa or more. 900 MPa or more, 950 MPa or more, 1000 MPa or more, 1100 MPa or more, 1150 MPa or more, 1200 MPa or more, 1250 MPa or more or 1300 MPa or more, particularly preferably 1350 MPa or more, and the thickness of the compressive stress layer is 10 μm or more, 15 μm or more 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, or 40 μm or more, preferably 45 μm or more.

In the tempered glass of the present invention, it is possible to obtain a suitable tempered glass by appropriately selecting a suitable content range and suitable characteristics of each component. Among them, particularly preferred tempering glasses are as follows.
(1) As a glass composition, SiO ₂ 50-80%, Al ₂ O ₃ 10-30%, B ₂ O ₃ 0-6%, Na ₂ O 5-25%, MgO 0-10% in mol%. Contains, substantially no As ₂ O ₃ , Sb ₂ O ₃ , PbO and F, and the crack generation rate is 80% or less.
(2) The thickness is 0.3 to 2.0 mm, the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, the thickness of the compressive stress layer is 10 μm or more and 60 μm or less, and the strain A point is 620 degreeC or more, and a crack generation rate is 80% or less.
(3) The thickness is 0.7 to 2.0 mm, the compressive stress value of the compressive stress layer is 1000 MPa or more, the thickness of the compressive stress layer is 40 μm or more, the strain point is 620 ° C. or more, and cracks are generated. The rate is 80% or less, and ΔCS is 100 MPa or less.

In the ion exchange treatment, the temperature of the KNO ₃ molten salt is preferably 390 to 550 ° C., the ion exchange time is preferably 0.5 to 10 hours, and particularly preferably 1 to 8 hours. If it does in this way, it will become easy to form a compressive stress layer appropriately. Incidentally, the reinforcing glass of the present invention has a glass composition described above, without using a mixture of KNO ₃ molten salt and NaNO ₃ molten salt, increasing the compressive stress value and thickness of the compression stress layer Can do.

The tempered glass (tempering glass) of the present invention can be produced as follows.

First, a glass raw material prepared so as to have the above glass composition is put into a continuous melting furnace, heated and melted at 1500 to 1700 ° C., clarified, fed into a molding apparatus, shaped into a flat plate shape, etc. The glass for reinforcement | strengthening can be produced by cooling.

It is preferable to adopt an overflow down draw method as a method of forming into a flat plate shape. The overflow downdraw method is a method capable of producing a large number of high-quality glass plates and easily producing a large glass plate. Furthermore, in the overflow downdraw method, alumina or zirconia is used as the molded body refractory. The tempered glass of the present invention has good compatibility with alumina and zirconia, particularly alumina (it is difficult to react with the molded body to generate bubbles and blisters).

In addition to the overflow downdraw method, various molding methods can be employed. For example, a forming method such as a float method, a downdraw method (slot down method, redraw method, etc.), a rollout method, a press method, or the like can be employed.

Next, tempered glass can be produced by tempering the obtained tempered glass. The time for cutting the tempered glass into a predetermined dimension may be before the tempering treatment or after the tempering treatment.

As the reinforcing treatment, an ion exchange treatment is preferable. The conditions for the ion exchange treatment are not particularly limited, and an optimum condition may be selected in consideration of the viscosity characteristics, application, thickness, internal tensile stress, dimensional change, and the like of the glass. For example, the ion exchange treatment can be performed by immersing in KNO ₃ molten salt at 390 to 550 ° C. for 1 to 8 hours. In particular, when K ions in the KNO ₃ molten salt are ion exchanged with Na components in the glass, a compressive stress layer can be efficiently formed on the surface of the glass.

Hereinafter, the present invention will be described based on examples. The following examples are merely illustrative. The present invention is not limited to the following examples.

Tables 1 to 12 show examples of the present invention (sample Nos. 1 to 68).

Each sample in the table was prepared as follows. First, glass raw materials were prepared so as to have the glass composition in the table, and were melted at 1600 ° C. for 21 hours using a platinum pot. Thereafter, the obtained molten glass was poured onto a carbon plate and formed into a flat plate shape. Various characteristics were evaluated about the obtained glass plate.

The density ρ is a value measured by the well-known Archimedes method.

The strain point Ps and the annealing point Ta are values measured based on the method of ASTM C336.

The softening point Ts is a value measured based on the method of ASTM C338.

The temperature at a high temperature viscosity of 10 ^4.0 dPa · s, 10 ^3.0 dPa · s, 10 ^2.5 dPa · s is a value measured by a platinum ball pulling method.

The thermal expansion coefficient α is a value obtained by measuring an average thermal expansion coefficient in a temperature range of 25 to 380 ° C. using a dilatometer.

The Young's modulus E is a value measured by a well-known resonance method.

The liquid phase temperature TL is passed through a standard sieve 30 mesh (500 μm), the glass powder remaining on 50 mesh (300 μm) is put in a platinum boat and kept in a temperature gradient furnace for 24 hours, and then the platinum boat is taken out. By observation, the highest temperature at which devitrification (crystal foreign matter) was observed inside the glass was set.

The liquid phase viscosity log η _TL is a value obtained by measuring the viscosity of the glass at the liquid phase temperature by a platinum ball pulling method.

First, in a constant temperature and humidity chamber maintained at a humidity of 30% and a temperature of 25 ° C., a Vickers indenter set to a load of 1000 gf was driven into the glass surface (optical polishing surface) for 15 seconds, and 15 seconds later, The number of cracks generated from the four corners is counted (maximum 4 for each indentation), and this operation is repeated 50 times in total to obtain the total number of cracks generated, then (total number of cracks generated / 200) × 100 It is the value calculated by the formula.

The compatibility with alumina refractories was evaluated as follows. Each sample was kept in contact with the alumina refractory at a viscosity of 10 ^4.5 dPa · s for 48 hours, and then the contact interface between each sample and the alumina refractory was observed to determine the number density of devitrified beads (pieces / mm ² ) Was measured.

As is clear from Tables 1 to 12, sample no. Nos. 1 to 68 had a density of 2.46 g / cm ³ or less, a strain point of 601 ° C. or more, and a crack generation rate of 68% or less, and were suitable as a tempered glass material, that is, a tempered glass. Further, since the liquid phase viscosity is 10 ^5.2 dPa · s or more and the compatibility with the alumina refractory is good, it can be formed into a flat plate shape by the overflow down draw method, and the temperature at a viscosity of 10 ^2.5 dPa · s is 1702. Since it is below ℃, it is considered that a large amount of glass plates can be produced at low cost. In addition, although the glass composition in the surface layer of glass is microscopically different before and after the tempering treatment, the glass composition is not substantially different when viewed as the whole glass.

Next, after optical polishing was performed on both surfaces of each sample, ion exchange treatment was performed by immersing in KNO ₃ molten salt at 400 ° C. for 4 hours. The surface of each sample was washed after the ion exchange treatment. Subsequently, the compressive stress value (CS ₄₀₀ ) and thickness (DOL ₄₀₀ ) of the surface compressive stress layer are calculated from the number of interference fringes observed using a surface stress meter (FSM-6000 manufactured by Toshiba Corporation) and the distance between the interference fringes. did. In the calculation, the refractive index of each sample was set to 1.50 and the optical elastic constant was set to 30 [(nm / cm) / MPa].

Further, after performing optical polishing on both surfaces of each sample, ion exchange treatment was performed by immersing in KNO ₃ molten salt at 430 ° C. for 4 hours. The surface of each sample was washed after the ion exchange treatment. Subsequently, the compressive stress value (CS ₄₃₀ ) and thickness (DOL ₄₃₀ ) of the surface compressive stress layer are calculated from the number of interference fringes observed using a surface stress meter (FSM-6000 manufactured by Toshiba Corporation) and the distance between the interference fringes. did. In the calculation, the refractive index of each sample was set to 1.50 and the optical elastic constant was set to 30 [(nm / cm) / MPa].

For each sample, ΔCS was calculated from the equation: ΔCS = CS ₄₀₀ −CS ₄₃₀ .

As is clear from Tables 1 to 12, sample no. From 1 to 68, CS ₄₃₀ was 1114 MPa or more, DOL ₄₃₀ was 38 μm or more, and ΔCS was small.

The tempered glass and the tempered glass of the present invention are suitable as a glass substrate for a mobile phone, a digital camera, a PDA or other cover glass, or a touch panel display. The tempered glass and the tempered glass of the present invention are used for applications requiring high mechanical strength in addition to these applications, such as window glass, magnetic disk substrates, flat panel display substrates, and solar cell cover glasses. Application to cover glass for solid-state imaging devices and tableware can be expected.

Claims

A tempered glass having a compressive stress layer on the surface, and the glass composition is SiO 2 50-80%, Al 2 O 3 10-30%, B 2 O 3 0-6%, Na 2 O 5 in mol%. A tempered glass containing ˜25%, MgO 0˜10%, and substantially free of As 2 O 3 , Sb 2 O 3 , PbO and F.
The glass composition is SiO 2 50-80%, Al 2 O 3 12-18%, B 2 O 3 0-3%, Na 2 O 12-18%, K 2 O 0-2%, MgO in mol%. A tempered glass comprising 0.1 to 4%, CaO 0 to 2%, and having a molar ratio Na 2 O / Al 2 O 3 of 0.6 to 1.6.
The tempered glass according to claim 1 or 2, wherein a crack occurrence rate before the tempering treatment is 80% or less.
The compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, and the thickness of the compressive stress layer is 10 µm or more and 60 µm or less. The tempered glass described.
The tempered glass according to any one of claims 1 to 4, wherein the strain point is 590 ° C or higher.
The tempered glass according to any one of claims 1 to 5, wherein the liquidus temperature is 1250 ° C or lower.
The tempered glass according to any one of claims 1 to 6, wherein the liquid phase viscosity is 10 4.5 dPa · s or more.
The tempered glass according to any one of claims 1 to 7, wherein the temperature at a viscosity of 10 4.0 dPa · s is 1400 ° C or lower.
9. The devitrification crystal generated at the contact interface when contacting with an alumina refractory for 48 hours at a viscosity of 10 4.5 dPa · s is 1 piece / mm 2 or less. Tempered glass as described in 2.
The tempered glass according to any one of claims 1 to 9, which has a flat plate shape.
The tempered glass according to any one of claims 1 to 10, wherein the thickness is 0.3 to 2.0 mm.
The tempered glass according to any one of claims 1 to 11, which is formed by an overflow downdraw method.
The tempered glass according to any one of claims 1 to 12, which is used for a touch panel display.
The tempered glass according to any one of claims 1 to 12, which is used for a cover glass of a mobile phone.
The tempered glass according to any one of claims 1 to 12, which is used for a cover glass of a solar cell.
The tempered glass according to any one of claims 1 to 12, which is used as a protective member for a display.
The glass composition is SiO 2 50-80%, Al 2 O 3 12-18%, B 2 O 3 0-3%, Na 2 O 12-18%, K 2 O 0-2%, MgO in mol%. 0.1 to 4%, CaO 0 to 2%, molar ratio Na 2 O / Al 2 O 3 is 0.6 to 1.6, substantially As 2 O 3 , Sb 2 O 3 , It does not contain PbO and F, the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, the thickness of the compressive stress layer is 10 μm or more and 60 μm or less, and the strain point is 590 ° C. or more. The liquid phase temperature is 1250 ° C. or less, the liquid phase viscosity is 10 4.5 dPa · s or more, the crack generation rate before the strengthening treatment is 80% or less, and the viscosity of 10 4.5 dPa · s is used as an alumina refractory. When contacted for 48 hours, the number of devitrified crystals generated at the contact interface is 1 / mm 2 or less. A tempered glass having a thickness of 0.3 to 2.0 mm and a flat plate shape.
As a glass composition, it contains SiO 2 50-80%, Al 2 O 3 10-30%, B 2 O 3 0-6%, Na 2 O 5-25%, MgO 0-10% in mol%. A tempered glass characterized by substantially not containing As 2 O 3 , Sb 2 O 3 , PbO and F.
The tempered glass according to claim 18, wherein a crack occurrence rate is 80% or less.
The thickness is 0.3 to 2.0 mm, the compressive stress value of the compressive stress layer is 900 MPa or more and 1500 MPa or less, the thickness of the compressive stress layer is 10 μm or more and 60 μm or less, and the strain point is 590. A tempered glass having a crack generation rate of 80% or less at a temperature of not lower than ° C.
The thickness is 0.7 to 2.0 mm, the compressive stress value of the compressive stress layer is 1000 MPa or more, the thickness of the compressive stress layer is 40 μm or more, the strain point is 620 ° C. or more, and the crack occurrence rate is 80 Glass for tempering characterized by being less than or equal to%.
The tempered glass according to any one of claims 18 to 21, wherein ΔCS is 100 MPa or less.