JP5546058B2 - Tempered glass, tempered glass and method for producing tempered glass - Google Patents

Description

  The present invention relates to tempered glass, and more particularly to tempered glass suitable for exterior parts such as mobile PCs. The present invention relates to glass, and more particularly to glass for strengthening suitable for exterior parts such as mobile PCs.

  Mobile phones equipped with a touch panel are widely used, and glass reinforced by ion exchange or the like (so-called tempered glass) is being used as a cover glass for mobile phones. Since tempered glass has higher mechanical strength than unstrengthened glass, it is suitable for this application (see Patent Document 1 and Non-Patent Document 1).

  In recent years, touch panels are being installed in applications other than mobile phones, and depending on the application, exterior parts having a specific shape, for example, a curved shape, are required. In order to apply tempered glass to these uses, it is necessary to process the tempered glass into a specific shape, for example, a curved shape. The tempered glass having a specific shape can be prepared by first forming molten glass to produce a flat plate-shaped glass, etc., and then deforming the glass into a specific shape by thermal processing, followed by a tempering treatment (Patent Document 2). 3).

  Therefore, these tempered glasses are required to have characteristics such as excellent mechanical processability, that is, a low softening point, in addition to high mechanical strength.

JP 2006-83045 A US Pat. No. 7,168,047 JP 2001-247342 A

Tetsuro Izumiya et al., “New Glass and its Properties”, first edition, Management System Research Institute, Inc., August 20, 1984, p. 451-498

  If the compressive stress value of the compressive stress layer formed on the surface is increased and the thickness of the compressive stress layer is increased, the mechanical strength of the tempered glass can be increased.

However, it is difficult to increase the thickness of the compressive stress layer and lower the softening point while increasing the compressive stress value of the compressive stress layer. In order to increase the thickness of the compressive stress layer while increasing the compressive stress value of the compressive stress layer, it is necessary to introduce components that improve ion exchange performance such as Al ₂ O ₃ into the glass composition. This is because when the element is introduced, the softening point increases.

  Then, this invention makes it a technical subject to obtain the tempered glass which has specific shape, for example, curved surface shape, by creating the tempered glass with a low softening point, having high mechanical strength.

As a result of various studies, the present inventor has found that if the β-OH value is appropriately controlled, the softening point can be lowered while optimizing the compressive stress value and thickness of the compressive stress layer, and is proposed as the present invention. To do. That is, the tempered glass of the present invention is a tempered glass having a compressive stress layer on the surface, and the glass composition is SiO ₂ 45 to 75%, Al ₂ O ₃ 5 to 30%, Li ₂ O + Na _{2 in} mass%. It contains O + K ₂ O 0.1-30 % , BaO 0-0.8% and β-OH value is 0.3-1 / mm, and it is heat-processed from flat glass to shapes other than flat glass It is characterized by being made. Here, the “β-OH value” refers to a value obtained by measuring the transmittance of glass using FT-IR and using Equation 1 below.

The β-OH value is determined by (1) selecting a raw material having a high water content (for example, a hydroxide raw material), (2) adding water to the raw material, and (3) a component for reducing the water content in the glass (Cl , SO ₃ etc.) is reduced or not used. (4) Adopting oxygen combustion at the time of melting, or introducing water vapor directly into the melting furnace to increase the amount of water in the furnace atmosphere. (5) Steam bubbling is performed in the molten glass, (6) the glass is melted in a large melting furnace, (7) the flow rate of the molten glass is decreased, and the like.

  The tempered glass of the present invention is preferably heat-processed from a flat glass, and the flat glass is preferably formed by an overflow down draw method.

  The tempered glass of the present invention is preferably ion-exchanged, and the compressive stress layer has a compressive stress value of 50 MPa or more and the compressive stress layer has a thickness of 10 μm or more. Here, “compressive stress value of compressive stress layer” and “thickness of compressive stress layer” are the values obtained by observing the number of interference fringes and their intervals using a surface stress meter, and calculating the compressive stress value and thickness of the surface. It is.

  The tempered glass of the present invention preferably has a softening point of 900 ° C. or lower. Here, the “softening point” refers to a value measured based on the method of ASTM C338.

  The tempered glass of the present invention preferably has a strain point of 400 ° C. or higher. Here, the “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 1200 ° C. or lower. Here, the “liquid phase temperature” refers to a temperature gradient furnace in which glass is crushed, passed through a standard sieve 30 mesh (a sieve opening of 500 μm), and glass powder remaining in a 50 mesh (a sieve opening of 300 μm) is placed in a platinum boat. It is the value which measured the temperature which hold | maintains for 24 hours and crystal | crystallization precipitates.

The tempered glass of the present invention preferably has a liquidus viscosity of 10 ⁴ dPa · s or more. Here, the “liquid phase viscosity” is a value obtained by measuring the viscosity of the glass at the liquid phase temperature by a platinum ball pulling method.

The tempered glass of the present invention preferably has a thermal expansion coefficient of 50 to 110 × 10 ⁻⁷ / ° C. Here, the “thermal expansion coefficient” is a value measured with a dilatometer, and shows an average value in a temperature range of 30 to 380 ° C.

  The tempered glass of the present invention preferably has a curved portion.

  The tempered glass of the present invention preferably has a stepped shape portion.

Reinforced glass of the present invention has a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, BaO 0~0 It is preferable that it contains 0.8% and has a β-OH value of 0.3 to 1 / mm, and is thermally processed from a flat glass to a shape other than a flat plate.

  The reinforcing glass of the present invention is preferably heat-processed from flat glass.

  The tempered glass of the present invention is preferably heat-processed from a flat glass, and the flat glass is preferably formed by an overflow down draw method.

  The tempered glass of the present invention preferably has a softening point of 900 ° C. or lower.

  The tempered glass of the present invention preferably has a strain point of 400 ° C. or higher.

  The tempered glass of the present invention preferably has a liquidus temperature of 1200 ° C. or lower.

The tempered glass of the present invention preferably has a liquidus viscosity of 10 ⁴ dPa · s or more.

The tempered glass of the present invention preferably has a thermal expansion coefficient of 50 to 110 × 10 ⁻⁷ / ° C.

  The tempered glass of the present invention preferably has a curved portion.

  The tempered glass of the present invention preferably has a stepped shape portion.

  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 preferably forms a compressive stress layer 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 glass surface by ion exchange at a temperature below the strain point. If the compressive stress layer is formed by the chemical strengthening method, the ion exchange treatment can be performed even if the glass is thin, and a desired mechanical strength can be obtained. Furthermore, if the compressive stress layer is formed by a chemical tempering method, unlike a physical tempering method such as an air cooling tempering method, even if the tempered glass is cut after the tempering treatment, the tempered glass is not easily broken.

  In order to produce tempered glass, it is necessary to perform a tempering treatment after the molten glass is formed into a predetermined shape. As described above, the strengthening process is desirably performed by an ion exchange process. The ion exchange treatment can be performed, for example, by immersing the glass in a potassium nitrate solution at 400 to 550 ° C. for 1 to 8 hours. What is necessary is just to select optimal conditions for the ion exchange conditions in consideration of the viscosity characteristics of glass, application, plate thickness, internal tensile stress, and the like.

  In the tempered glass of the present invention, the lower limit range of the β-OH value is 0.3 / mm or more, 0.32 / mm or more, 0.34 / mm or more, 0.35 / mm or more, 0.4 / mm. Or more, 0.45 / mm or more, 0.5 / mm or more, 0.55 / mm or more, particularly preferably 0.6 / mm or more, and the upper limit is 1 / mm or less, 0.9 / mm or less, 0.8 / mm or less, especially 0.7 / mm or less is preferable. If the β-OH value is less than 0.3 / mm, it is difficult to lower the softening point, and it is difficult to perform heat processing, or even if heat processing can be performed, the burden on the mold increases. As a result, the manufacturing cost of tempered glass increases. On the other hand, if the β-OH value is greater than 1 / mm, the glass network is likely to be damaged, so that the stress is easily relaxed and it is difficult to increase the mechanical strength of the tempered glass. That is, if the glass network is damaged, the compressive stress of the compressive stress layer is easily relaxed during the ion exchange process, and it is difficult to increase the compressive stress value of the compressive stress layer.

In the tempered glass of the present invention, it is preferable to use aluminum hydroxide, zirconium oxide hydrate or the like. In this way, the β-OH value can be increased while promoting the solubility of the glass batch. In order to improve the ion exchange performance, it is necessary to increase the raw materials of Al ₂ O ₃ , ZrO ₂ , TiO _{2 and} the like which are difficult to dissolve. However, if these raw materials are increased, Al ₂ O ₃ which is difficult to dissolve, etc. Tends to flow out as undissolved material. However, if aluminum hydroxide, zirconium oxide hydrate, or the like is used, the solubility of the glass batch can be increased, and generation of undissolved spots such as Al ₂ O ₃ that is difficult to dissolve can be prevented.

In the tempered glass of the present invention, the compressive stress value of the compressive stress layer is preferably 50 MPa or more, 100 MPa or more, 300 MPa or more, 500 MPa or more, 600 MPa or more, particularly 700 MPa or more. As the compressive stress value of the compressive stress layer increases, the mechanical strength of the tempered glass increases. On the other hand, when an extremely large compressive stress is formed on the surface, microcracks are generated on the surface, and conversely, the mechanical strength of the tempered glass may be reduced. Further, if an excessively large compressive stress is formed on the surface, the inherent tensile stress may become extremely high. Therefore, the compressive stress of the compressive stress layer is preferably 1300 MPa or less. In order to increase the compressive stress value of the compressive stress layer, the content of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , MgO, ZnO in the glass composition is increased, the content of SrO, BaO is decreased, and ion exchange is performed. What is necessary is just to shorten time or to lower the ion exchange temperature.

When the tempered glass is mounted on the touch panel, the end user has more opportunities to trace the surface of the tempered glass with his / her finger. Therefore, the mechanical strength of the tempered glass is likely to decrease due to surface scratches or the like. In order to maintain the mechanical strength of the tempered glass, it is effective to increase the thickness of the compressive stress layer. In the tempered glass of the present invention, the thickness of the compressive stress layer is preferably 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, particularly 60 μm or more. As the thickness of the compressive stress layer increases, the tempered glass is more difficult to break even if the tempered glass is deeply damaged. On the other hand, when the thickness of the compressive stress layer is too large, it becomes difficult to cut the tempered glass. Therefore, the thickness of the compressive stress layer is preferably 200 μm or less. In order to increase the thickness of the compressive stress layer, the content of Al ₂ O ₃ , K ₂ O, TiO ₂ , ZrO ₂ , MgO, ZnO in the glass composition is increased, the content of SrO, BaO is decreased, What is necessary is just to lengthen ion exchange time or raise ion exchange temperature.

  In the tempered glass of the present invention, the internal tensile stress value calculated by the following formula 2 is preferably 200 MPa or less, 150 MPa or less, 100 MPa or less, particularly 50 MPa or less. The smaller the internal tensile stress value, the lower the probability that the tempered glass will break due to internal defects. However, if the internal tensile stress value is too small, the compressive stress value and thickness of the compressive stress layer on the surface will decrease. Since it becomes small, the internal tensile stress value is preferably 1 MPa or more, 10 MPa or more, and particularly preferably 15 MPa or more.

The tempered glass of the present invention contains, as a glass composition, by mass%, SiO ₂ 45 to 75%, Al ₂ O ₃ 0 to 30%, Li ₂ O + Na ₂ O + K ₂ O 0.1 to 30%. The reason why the glass composition range is regulated as described above in the tempered glass of the present invention will be described below.

SiO ₂ is a component that forms a glass network, and the content thereof is 45 to 75%, preferably 50 to 70%, more preferably 50 to 63%, still more preferably 52 to 63%, and particularly preferably 52. ~ 60%. If the SiO ₂ content is too large, the meltability and moldability will be lowered, and the thermal expansion coefficient will be too low, making it difficult to match the thermal expansion coefficient of the surrounding materials. On the other hand, if the content of SiO ₂ is too small, it becomes difficult to vitrify, the thermal expansion coefficient becomes too high, and the thermal shock resistance tends to be lowered.

Al ₂ O ₃ is a component that improves ion exchange performance, and is a component that increases the strain point and Young's modulus, and its content is 5 to 30%. When the content of Al ₂ O ₃ is too large, devitrification crystal glass is easily precipitated, the moldability tends to decrease, it becomes difficult to mold the glass flat plate shape, especially an overflow down draw method and the like. Also, if the content of Al ₂ O ₃ is too large, the thermal expansion coefficient will be too low and it will be difficult to match the thermal expansion coefficient of the surrounding materials, or the high temperature viscosity will be too high, making it difficult to melt the glass. . Furthermore, the softening point becomes high, the temperature of thermal processing becomes too high, and particularly the temperature at the time of press molding becomes too high, which may promote deterioration of the mold. On the other hand, when the content of Al ₂ O ₃ is too small, resulting is a possibility which can not be sufficiently exhibited ion exchange performance. Judging from the above viewpoint, the upper limit range of Al ₂ O ₃ is 25% or less, 23% or less, 22% or less, 20% or less, 19% or less, 18% or less, 17% or less, particularly 16.5%. The following is preferred. The lower limit range of Al ₂ O ₃ is preferably 10% or more, 12% or more, 13% or more, and particularly preferably 14% or more.

Li ₂ O + Na ₂ O + K ₂ O is an ion exchange component, and is a component that lowers the high-temperature viscosity and improves meltability and moldability. If there is too much Li ₂ O + Na ₂ O + K ₂ O, in addition to the glass becoming more devitrified, the thermal expansion coefficient becomes too high, the thermal shock resistance is lowered, or the thermal expansion coefficient of the surrounding material is matched. It becomes difficult. _Further, when the _{Li 2 O + Na 2 O +} K 2 O is too large, the strain point excessively lowers, it may become difficult to increase the compression stress value. _Further, when the _{Li 2 O + Na 2 O +} K 2 O is too large, there are cases where the viscosity is lowered in the vicinity of the liquidus temperature, it is difficult to ensure a high liquidus viscosity. Therefore, the content of Li ₂ O + Na ₂ O + K ₂ O is 30% or less, preferably 25% or less, particularly preferably 20% or less. On the other _hand, there is a case where the _{Li 2 O + Na 2 O +} K 2 O is too small, or decreased the ion exchange performance and meltability, softening point becomes unduly high. Therefore, the content of Li ₂ O + Na ₂ O + K ₂ O is 0.1% or more, preferably 8% or more, 10% or more, 13% or more, and particularly preferably 15% or more.

Li ₂ O is an ion exchange component, and is a component that lowers the high-temperature viscosity and improves the meltability and moldability. Li ₂ O is a component that improves the Young's modulus. Furthermore, Li ₂ O has a high effect of increasing the compressive stress value among alkali metal oxides. However, if the content of Li ₂ O is too large, the liquid phase viscosity is lowered and the glass is liable to be devitrified, the thermal expansion coefficient is too high, and the thermal shock resistance is lowered. 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, particularly the strain point, is excessively decreased, stress relaxation is likely to occur, and conversely, the compressive stress value may be decreased. Therefore, the content of Li ₂ O is 0 to 10%, 0 to 8%, 0 to 6%, 0 to 4%, 0 to 3%, 0 to 2%, 0 to 1%, 0 to 0.5%. In particular, 0 to 0.1% is preferable.

Na ₂ O is an ion exchange component, is a component that lowers the high temperature viscosity and improves meltability and moldability, and is a component that improves devitrification resistance, and its content is 0 to 20%, 8 to 16%, 8 to 15%, 9 to 15%, 10 to 15%, 11 to 15%, particularly 12 to 15% are preferable. When the content of Na 2 _O is too large, the thermal expansion coefficient becomes too high, the thermal shock resistance becomes difficult to match or decreased, the thermal expansion coefficient with those of peripheral materials. Further, when the content of Na 2 _O is too large, or the strain point is lowered, component balance of the glass composition is impaired, devitrification resistance conversely tends to decrease. On the other hand, when the content of Na ₂ O is too small, the meltability is lowered, the thermal expansion coefficient is lowered too much, the softening point becomes too high, or the ion exchange performance tends to be lowered.

K ₂ O is a component that improves ion exchange performance, and has a high effect of increasing the thickness of the compressive stress layer among alkali metal oxides. K ₂ O is a component that lowers the high-temperature viscosity and improves the meltability and moldability. Furthermore, K ₂ O is also a component that improves devitrification resistance. When the content of K 2 _O is too large, the thermal expansion coefficient becomes too high, the thermal shock resistance becomes difficult to match or decreased, the thermal expansion coefficient with those of peripheral materials. If the content of K 2 _O is too large, or the strain point is lowered, component balance of the glass composition is impaired, devitrification resistance conversely tends to decrease. In view of the above point, the content of _{K 2} O is preferably 0%, _{K 2} O of the upper range is 8% or less, 7% or less, 6% or less, more preferably in particular _{5%, K} 2 O The lower limit range is more preferably 0.1% or more, 0.5% or more, 1% or more, particularly 2% or more in consideration of the thickness of the compressive stress layer.

  In addition to the above components, the following components can be added to the glass composition.

B ₂ O ₃ is a component that has the effect of lowering the liquidus temperature, the high-temperature viscosity, and the density, and improves the ion exchange performance, particularly the compressive stress value, and its content is 0 to 10%, 0 to 5%. 0 to 3%, particularly 0 to 2% is preferable. When the content of B ₂ O ₃ is too large, or scorch is generated on the surface by ion exchange, or water resistance is lowered, the liquidus viscosity may be decreased. In particular, in the tempered glass of the present invention, when an alkali metal oxide is contained in the glass composition, if the content of B ₂ O ₃ is too large, the B ₂ O ₃ component and the alkali component in the glass are melted at the time of melting. There is a risk that the refractory will be eroded significantly and the life of the kiln will be shortened. Further, the content of B ₂ O ₃ is too large, the thickness of the compressive stress layer tends to decrease.

  MgO + CaO + SrO + BaO (total amount of MgO, CaO, SrO, BaO) is a component that lowers the high-temperature viscosity to increase meltability and moldability, and increases the strain point and Young's modulus, and its content is 0 to 15%. 0 to 10%, 0 to 6%, particularly 0 to 5% is preferable. However, when there is too much content of MgO + CaO + SrO + BaO, there exists a tendency for a density and a thermal expansion coefficient to become high too much, devitrification resistance to fall, or ion exchange performance to fall.

  MgO is a component that lowers the viscosity at high temperature to increase the meltability and formability, and increases the strain point and Young's modulus. Especially in alkaline earth metal oxides, the effect of improving ion exchange performance is high. It is a component, and its content is preferably 0 to 10%, 0 to 6%, 0 to 4%, particularly preferably 0 to 3%. However, when there is too much content of MgO, a density and a thermal expansion coefficient will become high too much, or it will become easy to devitrify glass.

  CaO is a component that lowers the high-temperature viscosity to increase meltability and moldability, and increases the strain point and Young's modulus. Further, among the alkaline earth metal oxides, it is a component having a relatively high effect of improving the ion exchange performance, and its content is 0 to 10%, 0 to 8%, 0 to 6%, particularly 0 to 3%. Is preferred. However, if the content of CaO is too large, the density and thermal expansion coefficient become too high, the glass tends to devitrify, the component balance of the glass composition is impaired, and conversely the ion exchange performance decreases. There is.

  The content of SrO + BaO (total amount of SrO and BaO) is 0 to 5%, 0 to 3%, 0 to 2.5%, 0 to 2%, 0 to 1%, particularly preferably 0 to 0.1%. If the content of SrO + BaO is regulated within this range, the ion exchange performance can be effectively improved. In addition, since SrO + BaO has the effect | action which inhibits an ion exchange reaction, when SrO + BaO is excessive, it will become difficult to raise the mechanical strength of tempered glass.

SrO is a component that lowers the high-temperature viscosity to increase the meltability and moldability, and increases the strain point and Young's modulus, and its content is preferably 0 to 5%. BaO is lowering the high temperature viscosity, to enhance the meltability and the formability, or to enhance the strain point and the Young's modulus, and the content thereof is from 0 0.8%. When there is too much content of SrO and BaO, in addition to the tendency for ion exchange performance to fall, a density and a thermal expansion coefficient will become high too much, or it will become easy to devitrify glass. In particular, the SrO content is desirably 3% or less, 2% or less, 1% or less, 0.5% or less, and particularly preferably 0.1% or less. The BaO content is 0 . 5% or less, especially 0.1% or less is desirable.

When the value obtained by dividing MgO + CaO + SrO + BaO by the total amount of Li ₂ O + Na ₂ O + K ₂ O, that is, the value of (MgO + CaO + SrO + BaO) / (Li ₂ O + Na ₂ O + K ₂ O), the tendency to decrease devitrification resistance appears. Therefore, the value of mass fraction (MgO + CaO + SrO + BaO) / (Li ₂ O + Na ₂ O + K ₂ O) is preferably 0.5 or less, 0.4 or less, and particularly preferably 0.3 or less.

  ZnO is a component that improves the ion exchange performance, particularly a component that increases the compressive stress value, and a component that decreases the high temperature viscosity without decreasing the low temperature viscosity, and its content is 0 to 10%, 0 -5%, 0-3%, especially 0-1% are preferred. However, when the content of ZnO is too large, the glass tends to phase-divide, the devitrification resistance decreases, or the density tends to increase.

ZrO ₂ is a component that significantly improves the ion exchange performance and increases the viscosity and strain point in the vicinity of the liquid phase viscosity, and its content is 0 to 10%, 0 to 9%, 0.001 to 8%, 0.01 to 7%, 1 to 7%, 2 to 7%, 3 to 6%, particularly 3 to 5% are preferable. When the content of ZrO ₂ is too high, there are cases where the devitrification resistance is extremely lowered.

TiO ₂ is a component that improves ion exchange performance and a component that lowers the high-temperature viscosity, but if its content is too large, the glass is colored or the devitrification resistance is reduced, so its content The amount is preferably 1% or less, 0.5% or less, and particularly preferably 0.1% or less.

P ₂ O ₅ is a component that improves ion exchange performance, particularly a component that increases the thickness of the compressive stress layer, and its content is 0 to 8%, 5% or less, 4% or less, 2% or less, 0.5% or less, especially 0.1% or less is preferable. However, when the content of P ₂ O ₅ is too large, or glass phase separation, the water resistance tends to lower.

As a fining agent, 0 to 3% of one or more selected from the group of As ₂ O ₃ , Sb ₂ O ₃ , CeO ₂ , SnO ₂ , F, Cl, and SO ₃ can be added. However, As ₂ O ₃ , Sb ₂ O ₃ , F, particularly As ₂ O ₃ , Sb ₂ O ₃ are preferably refrained from use as much as possible from an environmental point of view, and each content is less than 0.1% Is preferred. Preferred fining agents _are SnO 2, _SO 3, Cl. The SnO ₂ content is preferably 0 to 1%, 0.01 to 0.5%, particularly preferably 0.05 to 0.4%. When the content of SnO ₂ is more than 1%, the devitrification resistance tends to decrease. The content of SO ₃ is 0 to 0.1%, 0.0001 to 0.1%, 0.0003 to 0.08%, 0.0005 to 0.05%, particularly 0.001 to 0.03%. preferable. When the content of SO ₃ is more than 0.1%, SO ₃ is reboiled at the time of melting, and the bubble quality tends to be lowered. The Cl content is preferably 0 to 0.5%, 0.001 to 0.1%, 0.001 to 0.09%, 0.001 to 0.05%, particularly preferably 0.001 to 0.03%. . If the Cl content is more than 0.5%, it becomes difficult to increase the β-OH value, and the metal wiring is easily corroded when a metal wiring pattern or the like is formed on the tempered glass.

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

  Since transition metal oxides such as Co and Ni are components that strongly color the glass and lower the transmittance, the content thereof is 0.5% or less, 0.1% or less, particularly 0.05% or less. It is desirable to adjust the amount of the glass raw material and / or cullet used so that the content is within the range.

PbO and Bi ₂ O ₃ are preferably used as little as possible from the environmental viewpoint, and their content is preferably less than 0.1%.

In the tempered glass of the present invention, the strain point is preferably 450 ° C. or higher, 460 ° C. or higher, 480 ° C. or higher, particularly 500 ° C. or higher. The higher the strain point, the better the heat resistance, and the compressive stress layer is less likely to disappear even if the tempered glass is heat-treated. In addition, when the strain point is high, stress relaxation is unlikely to occur during the ion exchange process, and thus a high compressive stress value is easily obtained. Furthermore, when the strain point is high, the temperature-decreasing rate can be increased in the temperature-decreasing step after the thermal processing, so that the process time of the thermal processing can be shortened and the productivity can be increased. In order to increase the strain point, the content of the alkali metal oxide in the glass composition is reduced, particularly the content of Li ₂ O is reduced, or the alkaline earth metal oxide, Al ₂ O ₃ , ZrO ₂ , P it may be increased content of ₂ O _5.

  In the tempered glass of the present invention, the softening point is 900 ° C or lower, 880 ° C or lower, 860 ° C or lower, 850 ° C or lower, 840 ° C or lower, 830 ° C or lower, 820 ° C or lower, 800 ° C or lower, 780 ° C or lower, 770 ° C or lower, In particular, 760 ° C. or lower is preferable. The lower the softening point, the better the heat processing at a low temperature. Also, the lower the softening point, the less the burden on the mold when press molding. The deterioration of a mold is often caused by a so-called oxidation reaction in which a metal material used for the mold reacts with oxygen in the atmosphere. When such an oxidation reaction occurs, a reaction product is formed on the surface of the mold, and it may be impossible to press-mold into a predetermined shape. Further, when an oxidation reaction occurs, ions in the glass may be reduced and foaming may occur. The lower the press molding temperature, that is, the lower the softening point, the more the oxidation reaction can be suppressed. Further, the lower the softening point, the lower the upper limit value of the press molding / thermal processing temperature can be reduced, so that the time for the subsequent annealing step can be shortened.

In the tempered glass of the present invention, the temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s is 1600 ° C. or lower, 1550 ° C. or lower, 1500 ° C. or lower, 1450 ° C. or lower, 1430 ° C. or lower, 1420 ° C. or lower, particularly 1400 ° C. or lower. preferable. The lower the temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s, the smaller the burden on the production equipment such as the melting furnace during melting, and the higher the bubble quality of the glass. That is, the lower the temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s, the cheaper the glass can be produced. The temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s corresponds to the melting temperature, and the lower the temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s, the more the glass can be melted at a low temperature. it can. In order to reduce the temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s, the content of alkali metal oxide, alkaline earth metal oxide, ZnO, B ₂ O ₃ , TiO ₂ is increased, or SiO ₂ , the content of al ₂ O ₃ may be reduced.

The tempered glass of the present invention, the density is 2.7 g / cm ³ or less, 2.6 g / cm ³ or less, in particular 2.55 g / cm ³ or less. The smaller the density, the lighter the glass. Here, “density” refers to a value measured by the well-known Archimedes method. In order to reduce the density, the content of SiO ₂ , P ₂ O ₅ , B ₂ O _{3 in} the glass composition is increased, or alkali metal oxide, alkaline earth metal oxide, ZnO, ZrO ₂ , TiO ₂ What is necessary is just to reduce content.

The tempered glass of the present invention, the thermal expansion coefficient of ^{50~110 × 10 -7 / ℃, 70~110} × 10 -7 / ℃, 75~105 × 10 -7 / ℃, especially 80 to 105 × ^{10 -7} / ° C is preferred. When the thermal expansion coefficient is in the above range, it becomes easy to match the thermal expansion coefficient of a member such as a metal or an organic adhesive, and it is possible to prevent peeling of the member such as a metal or an organic adhesive. Increasing the content of alkali metal oxides and alkaline earth metal oxides in the glass composition increases the thermal expansion coefficient, and conversely the alkali metal oxides and alkaline earth metal oxides in the glass composition. If the content is reduced, the thermal expansion coefficient is lowered.

In the tempered glass of the present invention, the liquidus temperature is preferably 1200 ° C. or lower, 1050 ° C. or lower, 1000 ° C. or lower, 950 ° C. or lower, 900 ° C. or lower, particularly 860 ° C. or lower. To lower the liquidus temperature, the content of Na ₂ O, K ₂ O, B ₂ O _{3 in} the glass composition is increased, or Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO _2. The content of can be reduced.

In the tempered glass of the present invention, the liquid phase viscosity is 10 ^4.0 dPa · s or more, 10 ^4.5 dPa · s or more, 10 ^5.0 dPa · s or more, 10 ^5.2 dPa · s or more, 10 ^{5. 3} dPa · s or more, 10 ^5.5 dPa · s or more, 10 ^5.7 dPa · s or more, 10 ^5.8 dPa · s or more, and particularly preferably 10 ^6.0 dPa · s or more. To increase the liquid phase viscosity, increase the content of Na ₂ O, K ₂ O in the glass composition, or decrease the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO ₂ do it. In addition, devitrification resistance and a moldability improve, so that liquid phase viscosity is high. Also, the lower the liquidus temperature, the better the devitrification resistance and the moldability. That is, the higher the liquid phase viscosity or the lower the liquid phase temperature, the more difficult it is for crystals to precipitate out of the glass, so heat processing can be performed at a low temperature.

A suitable content range and a suitable characteristic value of each component can be appropriately selected to obtain a preferred embodiment. Among these, the following aspect is more preferable for the tempered glass of the present invention.
(1) in _mass%, it contains _{SiO 2 45~75%, Al 2 O} 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, the 0 to 0.8% BaO, beta- OH value is 0.3-1 / mm,
(2) in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, B 2 O 3 0~4%, Li 2 O + Na 2 O + K 2 O 0.1~30%, BaO 0~0 .8% , β-OH value of 0.3-1 / mm,
(3) _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, B 2 O 3 0~5%, Li 2 O + Na 2 O + K 2 O 0.1~30%, BaO 0~0 .8% , β-OH value of 0.3-1 / mm,
(4) in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, B 2 O 3 0~5%, Li 2 O + Na 2 O + K 2 O 0.1~30%, Cl 0~0 0.1 % , BaO 0-0.8% , β-OH value 0.3-1 / mm,
(5) in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, B 2 O 3 0~5%, Li 2 O + Na 2 O + K 2 O 0.1~30%, Cl 0~0 0.01 % , BaO 0 to 0.8% , β-OH value 0.2 to 1 / mm,
(6) _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, Cl 0~0.01%, BaO 0~0. Containing 8% , β-OH value of 0.3-1 / mm,
(7) in _{mass%, SiO 2 50~75%, Al} 2 O 3 10~20%, B 2 O 3 0~5%, Li 2 O 0~10%, Na 2 O 10~20%, K 2 O 1~10%, CaO 0.1~10%, SrO 0~5%, BaO 0~ 0.8%, TiO 2 0~0.5%, containing 0~0.01% Cl, β-OH The value is 0.3-1 / mm,
(8) in _{mass%, SiO 2 50~60%, Al} 2 O 3 12~18%, B 2 O 3 0~3%, Li 2 O 0~1%, Na 2 O 10~20%, K 2 O 1~7%, CaO 0.1~10%, SrO 0~5%, BaO 0~ 0.8%, TiO 2 0~0.5%, containing 0~0.04% Cl, β-OH The value is 0.3-1 / mm,
(9) in _{mass%, SiO 2 50~60%, Al} 2 O 3 12~18%, B 2 O 3 0~3%, Li 2 O 0~1%, Na 2 O 10~20%, K 2 O 1~7%, CaO 0.1~10%, SrO 0~5%, BaO 0~ 0.8%, TiO 2 0~0.5%, containing 0~0.04% Cl, β-OH The value is 0.45 to 1 / mm.

  When used as an exterior part, the thickness of the tempered glass is 0.3 mm or more, 0.5 mm or more, 0.7 mm or more, 1.0 mm or more, 1.3 mm or more, particularly 1 in order to maintain the mechanical strength of the tempered glass. 0.5 mm or more is preferable. When used as a substrate, the thickness of the tempered glass is preferably 3.0 mm or less, 1.5 mm or less, 0.7 mm or less, 0.5 mm or less, particularly 0.3 mm or less in order to reduce the weight of the tempered glass.

  The tempered glass of the present invention preferably has an unpolished surface, and the average surface roughness (Ra) of the unpolished surface is preferably 10 mm or less, 5 mm or less, and particularly preferably 2 mm or less. When used as an exterior component, such a surface shape can impart an appropriate gloss to the tempered glass. “Average surface roughness (Ra)” refers to a value measured by a method based on SEMI D7-97 “Measurement method of surface roughness of FPD glass substrate”. The theoretical strength of glass is inherently very high, but breakage often occurs even at a stress much lower than the theoretical strength. This is because a small defect called Griffith flow occurs on the surface of the glass in a process after molding of the molten glass, such as a polishing process. Therefore, if the surface is unpolished, the mechanical strength of the original glass is hardly impaired, and the glass is difficult to break. If the entire surface (excluding the cut surface) is unpolished, the glass becomes more difficult to break. Further, if the surface is not polished, the polishing step can be omitted, and the manufacturing cost of the tempered glass can be reduced. In the tempered glass of the present invention, a chamfering process or the like may be applied to the cut surface in order to prevent a situation from breaking to the cut surface. In addition, if the molten glass is formed by the overflow down draw method, it is possible to obtain a flat glass having unpolished and good surface accuracy.

The tempered glass of the present invention is heat-processed into a shape other than a flat plate shape from a flat plate glass . If it does in this way, the tempered glass of a specific shape can be produced easily, and cost reduction of exterior parts can be achieved.

  The tempered glass of the present invention has a shape other than a flat plate shape, and preferably has a curved surface shape, an uneven shape, a corrugated shape, a stepped shape, and the like. If it does in this way, special shape exterior parts can be applied to a device provided with a touch panel.

  The tempered glass of the present invention is prepared by putting a glass batch prepared so as to have a predetermined glass composition into a continuous melting furnace, heating and melting at 1500 to 1600 ° C., clarifying, and then supplying the molten glass to a molding apparatus. Can be produced by forming and slowly cooling.

Various molding methods can be employed in the tempered glass of the present invention. For example, a molding method such as a down draw method (overflow down draw method, slot down method, redraw method, etc.), a float method, or a roll out method can be employed .

  The tempered glass of the present invention is preferably formed into a flat glass by an overflow down draw method. By doing so, it is possible to produce a flat plate-shaped glass that is unpolished and has good surface quality. The reason is that in the case of the overflow downdraw method, the surface to be the surface of the glass is not in contact with the bowl-like refractory and is molded in a free surface state. Here, the overflow down draw method is a flat plate shape in which molten glass is overflowed from both sides of a heat-resistant bowl-shaped structure, and the molten glass overflowed is joined at the lower end of the bowl-shaped structure and stretched downward. It is a method of manufacturing the glass. The structure and material of the bowl-shaped structure are not particularly limited as long as the dimensions and surface accuracy of the glass are in a desired state and a desired quality can be realized. Further, a force may be applied to the glass by any method in order to perform downward stretching. For example, a method may be adopted in which a heat-resistant roll having a sufficiently large width is rotated and stretched in contact with glass, or a plurality of pairs of heat-resistant rolls are contacted only near the end face of the glass. It is also possible to adopt a method of stretching by stretching.

Reinforced glass of the present invention has a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, BaO 0~0 .8% and a β-OH value of 0.3 to 1 / mm, and is heat-processed from a flat glass to a shape other than a flat plate. If it does in this way, thermal workability can be improved, improving ion exchange performance. Moreover, the glass for reinforcement | strengthening of this invention can be equipped with the technical characteristics (A suitable glass composition range, a suitable characteristic, a remarkable effect, etc.) similar to the tempered glass of this invention. Here, the description is omitted for convenience. A method of manufacturing a tempered glass of the present invention, as a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, A flat reinforcing glass is produced so that it contains BaO 0 to 0.8% and the β-OH value is 0.3 to 1 / mm, and the reinforcing glass is made into a shape other than the flat shape. After heat processing, a tempered glass is obtained by forming a compressive stress layer on the surface by ion exchange treatment.

  Hereinafter, based on an Example, this invention is demonstrated in detail. Tables 1 and 2 show Sample No. 1-8 are shown.

Each sample in the table was prepared as follows. First, a glass batch or the like is prepared so that the glass composition and β-OH value in the table are obtained (for example, the ratio of the oxide raw material to the hydroxide raw material is changed as the raw material for introducing Al ₂ O ₃ ). Then, it was melted at 1580 ° C. for 8 hours using a platinum pot. Next, the molten glass was poured out on a carbon plate, formed into a flat plate shape, and then optically polished. Various characteristics were evaluated about the obtained glass.

  The β-OH value was obtained by using the above mathematical formula 1 by measuring the transmittance of the glass using FT-IR.

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

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

The temperature corresponding to the high temperature viscosity of 10 ⁴ dPa · s, 10 ³ dPa · s, and 10 ^2.5 dPa · s is a value measured by a platinum ball pulling method.

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

  The thermal expansion coefficient is a value measured with a dilatometer, and shows an average value in a temperature range of 30 to 380 ° C.

  The liquid phase temperature is obtained by crushing glass, passing through a standard sieve 30 mesh (a sieve opening of 500 μm), putting the glass powder remaining at 50 mesh (a sieve opening of 300 μm) in a platinum boat, and keeping it in a temperature gradient furnace for 24 hours. The value at which the temperature at which crystals precipitate is measured.

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

The obtained glass was immersed in a KNO ₃ tank maintained at 440 ° C. for 8 hours to perform ion exchange treatment. After the ion exchange treatment, the compressive stress value and thickness of the compressive stress layer were measured. The compressive stress value and thickness of the compressive stress layer were calculated by observing the number of interference fringes and their intervals using a surface stress meter (FSM-6000 manufactured by Toshiba Corporation). In the calculation, the refractive index of each sample was 1.52, and the optical elastic constant was 28 [(nm / cm) / MPa].

  As is clear from Tables 1 and 2, as the β-OH value increases, the softening point decreases and thermal processing becomes easier, and as a result, it becomes easier to obtain a tempered glass having a specific shape.

  In the preparation of each sample in the table, for the convenience of explanation of the present invention, molten glass was poured out, formed into a flat plate shape, and then optically polished before ion exchange treatment. When manufacturing, it is preferable to form a flat glass by an overflow down draw method or the like and omit the polishing treatment, and it is preferable to perform an ion exchange treatment after the glass is heat-processed into a specific shape.

  The tempered glass of the present invention can be used for a cover glass of a mobile phone, a digital camera, a PDA, a touch panel display, etc., taking advantage of its excellent thermal processability, and exterior parts such as a mobile phone, a mobile PC, a pointing device, It is particularly suitable for exterior parts having a shape other than a flat plate shape. In addition to these uses, the tempered glass of the present invention is used for applications requiring high mechanical strength, such as window glass, magnetic disk substrates, flat panel display substrates, solar cell substrates and cover glasses, Application to cover glass for solid-state imaging devices and tableware can be expected.

Claims (22)

It is a tempered glass having a compressive stress layer on its surface, and the glass composition is SiO ₂ 45 to 75%, Al ₂ O ₃ 5 to 30%, Li ₂ O + Na ₂ O + K ₂ O 0.1 to 30% by mass%. , BaO 0 to 0.8% , β-OH value is 0.3 to 1 / mm, and is heat-treated from a flat glass to a shape other than a flat plate. Glass.   The tempered glass according to claim 1, wherein the flat glass is formed by an overflow downdraw method.   3. The tempered glass according to claim 1, wherein the tempered glass is ion-exchanged and has a compressive stress value of 50 MPa or more and a compressive stress layer thickness of 10 μm or more.   Softening point is 900 degrees C or less, Tempered glass in any one of Claims 1-3 characterized by the above-mentioned.   The tempered glass according to any one of claims 1 to 4, wherein the strain point is 400 ° C or higher.   Liquid phase temperature is 1200 degrees C or less, Tempered glass in any one of Claims 1-5 characterized by the above-mentioned. Liquid phase viscosity is 10 < ⁴ > dPa * s or more, Tempered glass in any one of Claims 1-6 characterized by the above-mentioned. A thermal expansion coefficient is 50-110x10 < ^-7 > / degreeC, Tempered glass in any one of Claims 1-7 characterized by the above-mentioned.   The tempered glass according to claim 1, which has a curved surface portion.   The tempered glass according to claim 1, comprising a stepped shape portion. As a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, containing 0 to 0.8% BaO, and A tempered glass having a β-OH value of 0.3 to 1 / mm and being thermally processed from a flat glass to a shape other than a flat glass. The tempered glass according to claim 11, wherein the flat glass is formed by an overflow downdraw method.   The glass for tempering according to claim 11 or 12, wherein a softening point is 900 ° C or less.   The tempered glass according to claim 11, wherein the strain point is 400 ° C. or higher.   Liquidus temperature is 1200 degrees C or less, Glass for strengthening in any one of Claims 11-14 characterized by the above-mentioned. Liquid phase viscosity is 10 < ⁴ > dPa * s or more, Tempering glass in any one of Claims 11-15 characterized by the above-mentioned. A thermal expansion coefficient is 50-110x10 < ^-7 > / degreeC, The glass for reinforcement | strengthening in any one of Claims 11-16 characterized by the above-mentioned.   The tempered glass according to claim 11, which has a curved surface portion.   The tempered glass according to claim 11, comprising a stepped shape portion. As a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 5 ~30%, Li 2 O + Na 2 O + K 2 O 0.1~30%, containing 0 to 0.8% BaO, and After producing a flat plate-shaped tempered glass so that the β-OH value is 0.3 to 1 / mm, after heat-processing the tempered glass into a shape other than the flat plate shape, by ion exchange treatment, A method for producing tempered glass, comprising forming a compressive stress layer on a surface to obtain tempered glass.   The method for producing tempered glass according to claim 20, wherein the tempered glass is thermally processed so as to have a curved surface portion.   The method for producing tempered glass according to claim 20 or 21, wherein the heat-processing is performed so as to have a stepped shape portion.