JP2016056029A - Tempered glass and glass for tempering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a high refractive index glass having high liquid phase viscosity and high mechanical strength.SOLUTION: A tempered glass according to the present invention has a compressive stress layer on its surface, where the compressive stress layer is formed by ion exchange treatment, and a refractive index nis 1.55-2.00.SELECTED DRAWING: None

Description

  The present invention relates to a tempered glass and a tempered glass. For example, the present invention relates to a tempered glass and a tempered glass suitable for organic EL devices, particularly organic EL lighting.

  In recent years, displays and illuminations using organic EL light emitting elements have been attracting increasing attention. These organic EL devices have a structure in which an organic light emitting element is sandwiched between glass plates on which a transparent conductive film such as ITO is formed. In this structure, when a current flows through the organic light emitting device, holes and electrons in the organic light emitting device associate to emit light. The emitted light enters the glass plate through a transparent conductive film such as ITO, and is emitted to the outside while being repeatedly reflected in the glass plate.

JP 2007-186407 A

Incidentally, the refractive index _{n d} of the organic light emitting element is 1.8 to 1.9, the refractive index _{n d} of the ITO is 1.9 to 2.0. In contrast, the refractive index _{n d} of the glass plate is usually about 1.5. For this reason, the conventional organic EL device has a problem in that the light generated from the organic light-emitting element cannot be efficiently extracted because the reflectance increases due to the difference in refractive index at the glass plate-ITO interface.

  Therefore, it has been studied to solve the above problem by increasing the refractive index of the glass plate.

In order to increase the refractive index of the glass plate, it is necessary to decrease the contents of SiO ₂ and Al ₂ O ₃ and increase the contents of SrO, BaO and the like. However, in this case, the glass plate tends to be structurally fragile, and the glass plate tends to be damaged.

  Therefore, the present invention has been made in view of the above circumstances, and a technical problem thereof is to create a high refractive index glass having high mechanical strength.

As a result of intensive studies, the present inventor has found that the above technical problem can be solved by subjecting a predetermined glass to ion exchange treatment, and proposes the present invention. That is, the tempered glass of the present invention, characterized in that the reinforced glass having a compressive stress layer on the surface, the compressive stress layer is formed by ion exchange treatment, the refractive index n _d is 1.55 to 2.00 And Here, “refractive index n _d ” is a measured value at the d-line (wavelength 587.6 nm) of the hydrogen lamp, and can be measured with a refractive index measuring device. For example, after preparing a rectangular parallelepiped sample of 25 mm × 25 mm × about 3 mm, the temperature range from (annealing point + 30 ° C.) to (strain point−50 ° C.) is gradually increased at a cooling rate of 0.1 ° C./min. It can measure by using the refractive index measuring device KPR-2000 by Shimadzu Corporation Corp., making it cool and then making the immersion liquid which a refractive index matches penetrate between glass.

Second, the tempered glass of the present invention has a glass composition, in _{mass%, SiO 2 20~70%, Li} 2 O + Na 2 O + K 2 O 0.1~30%, to contain 4 to 40% BaO preferable. In the field of optical glass, a glass having a high refractive index may be used (for example, see Patent Document 1). However, these glasses have a low liquidus viscosity, so that they are difficult to form into a flat plate shape and are not suitable for mass production. Therefore, if the glass composition range is regulated as described above, the devitrification resistance is improved, it becomes easy to form a flat plate shape, and the refractive index and the ion exchange performance are easily improved. Here, “Li ₂ O + Na ₂ O + K ₂ O” is the total amount of Li ₂ O, Na ₂ O and K ₂ O.

Third, the tempered glass of the present invention preferably contains TiO ₂ 1 to 10 wt% in the glass composition. If it does in this way, it will become easy to obtain high refractive index glass.

  Fourth, the tempered glass of the present invention is preferably used for an illumination device.

  Fifth, the tempered glass of the present invention is preferably used for organic EL lighting.

Sixth, reinforcing glass of the present invention is a reinforced glass to be subjected to ion exchange treatment, the refractive index n _d is equal to or is from 1.55 to 2.0.

  The tempered glass of the present invention has a compressive stress layer on the surface, and the compressive stress layer is formed by ion exchange treatment. The ion exchange treatment is a method of introducing alkali ions having a large ion radius to the surface of the glass at a temperature below the strain point of the glass. If the compressive stress layer is formed by ion exchange treatment, the compressive stress layer can be properly formed even when the glass is thin, and even if the tempered glass is cut after the compressive stress layer is formed, air cooling strengthening is possible. The tempered glass does not break easily like the physical tempering method.

The tempered glass of the present invention, the refractive index _{n d} is 1.55 or more, preferably 1.58 or more, 1.60 or more, particularly 1.62 or more. When the refractive index _{n d} is less than 1.55, it might become caught efficiently light by reflection ITO- glass interface. On the other hand, when the refractive index is high, the balance of the glass composition is lacking and the devitrification resistance tends to be lowered. Further, when the refractive index becomes extremely high, the reflectance at the air-glass interface becomes high, and it becomes difficult to increase the light extraction efficiency even if the glass surface is roughened. Therefore, the refractive index _nd is preferably 2.00 or less, 1.80 or less, 1.67 or less, 1.66 or less, and particularly 1.65 or less.

Tempered glass of the present invention has a glass composition, in _{mass%, SiO 2 20~70%, Li} 2 O + Na 2 O + K 2 O 0.1~30%, preferably contains 4 to 40% BaO. The reason for limiting the content range of each component as described above will be described below. In addition, in description of the following content ranges,% display represents the mass% except the case where there is particular notice.

The content of SiO ₂ is preferably 20 to 70%. When the content of SiO ₂ decreases, it becomes difficult to form a glass network structure, and vitrification becomes difficult. In addition, the high temperature viscosity is excessively lowered, making it difficult to ensure a high liquid phase viscosity. Therefore, the content of SiO ₂ is preferably 20% or more, 25% or more, 30% or more, 32% or more, 34% or more, particularly 36% or more. On the other hand, when the content of SiO ₂ increases, the refractive index, meltability, and moldability tend to decrease. Therefore, the content of SiO ₂ is preferably 70% or less, 65% or less, 60% or less, 55% or less, 52% or less, less than 50%, 48% or less, 45% or less, particularly 43% or less.

Li ₂ O, Na ₂ O, and K ₂ O are ion exchange components, and are components that lower the high-temperature viscosity and increase the meltability and moldability. When _{Li 2 O + Na 2 O +} K 2 O content is too small, the lowered melting property and formability, or excessively decreased thermal expansion coefficient, the ion exchange performance tends to decrease. However, if the content of Li ₂ O + Na ₂ O + K 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. In addition, the strain point may be excessively decreased, or the component balance of the glass composition may be lost, and the devitrification resistance may be decreased. Therefore, the content of Li ₂ O + Na ₂ O + K ₂ O is preferably 0.1-30%, 0.5-25%, 0.8-18%, 1-15%, 1.2-10%, especially 1.5-7%.

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. However, if the content of Li ₂ O is too large, the liquid phase viscosity decreases and the glass is liable to devitrify, the thermal expansion coefficient becomes too high, and the thermal shock resistance decreases, It becomes difficult to match the thermal expansion coefficient of the surrounding material. Furthermore, the low-temperature viscosity is excessively decreased, stress relaxation is likely to occur, and the compressive stress value may be decreased. Therefore, the content of Li ₂ O is preferably 0 to 4%, 0 to 2.5%, 0 to 2%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, particularly 0. ~ 0.3%.

Na ₂ O is an ion exchange component, and is a component that lowers the high temperature viscosity and improves the meltability and moldability. When the content of Na 2 _O is too small, the lowered melting property, or excessively decreased thermal expansion coefficient, the ion exchange performance tends to decrease. Therefore, a preferable lower limit range of Na ₂ O is 0.1% or more, 0.5% or more, 1% or more, 1.5% or more, 2% or more, particularly 3% 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. In addition, the strain point may be excessively decreased, or the component balance of the glass composition may be lost, and the devitrification resistance may be decreased. Further, the ion exchange performance becomes too high, and the tempered glass may be self-destructed after the ion exchange treatment of the thin glass plate. Therefore, the preferable upper limit range of Na ₂ O is 20% or less, 15% or less, 10% or less, 8% or less, and particularly 5% or less.

K ₂ O is a component that promotes ion exchange, and is a component that tends to increase the stress depth particularly in alkali metal oxides. Moreover, it is a component which reduces high temperature viscosity and improves a meltability and a moldability. It is also a component that improves 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. In addition, the strain point may be excessively lowered or the component balance of the glass composition may be lost, and the devitrification resistance may be deteriorated. Therefore, the content of K ₂ O is preferably 0 to 4%, 0 to 2.5%, 0 to 2%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, particularly 0. ~ 0.3%.

  BaO is preferably 4 to 40%. BaO is a component that increases the refractive index of alkaline earth metal oxides without significantly reducing the viscosity. However, as the content of BaO increases, the density and thermal expansion coefficient tend to increase, and the liquid phase viscosity tends to decrease. Moreover, when there is too much content of BaO, it will become difficult to give a high compressive stress to the glass surface by an ion exchange process. Therefore, the content of BaO is preferably 40% or less, 36% or less, 32% or less, 30% or less, 28% or less, particularly 26% or less. On the other hand, when the content of BaO decreases, it becomes difficult to obtain a desired refractive index and it is difficult to ensure a high liquid phase viscosity. Therefore, the BaO content is preferably 4% or more, 10% or more, 12% or more, 16% or more, and particularly 18% or more.

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

The content of Al ₂ O ₃ is preferably 0 to 20%. When the content of Al ₂ O ₃ is increased, devitrified crystals are likely to precipitate on the glass, the liquid phase viscosity is liable to be lowered, and the refractive index is liable to be lowered. Therefore, the content of Al ₂ O ₃ is preferably 20% or less, 15% or less, 10% or less, 8% or less, particularly 6% or less. On the other hand, when the content of Al ₂ O ₃ decreases, the ion exchange performance tends to be lowered. Therefore, the content of Al ₂ O ₃ is preferably 0.1% or more, 0.5% or more, 1% or more, 3% or more, 4% or more, particularly 5% or more.

The content of B ₂ O ₃ is preferably 0 to 35%. When the content of B ₂ O ₃ increases, the refractive index and Young's modulus tend to decrease. Therefore, the content of B ₂ O ₃ is preferably 35% or less, 25% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 10% or less. Incidentally, the content of B ₂ O ₃ is reduced, the liquid phase temperature tends to decrease. Therefore, the content of B ₂ O ₃ is preferably 0.1% or more, 1% or more, 2% or more, 4% or more, particularly 5% or more.

The content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is 30.5 to 80%. When the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ decreases, it becomes difficult to form a glass network structure and vitrification becomes difficult. Further, the viscosity of the glass is excessively lowered, and it becomes difficult to ensure a high liquid phase viscosity. Therefore, the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 30.5% or more, 35% or more, 40% or more, 42% or more, 46% or more, 48% or more, particularly 50% or more. is there. On the other hand, when the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ increases, the meltability and moldability tend to be lowered. Furthermore, it becomes difficult to obtain a glass having a high refractive index as defined in the present invention. Therefore, the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 57% or less, particularly 55% or less. Here, “SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ” refers to the total amount of SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ .

Weight ratio _SiO 2 _/ B 2 _{O 3} 1 to 20 is preferred. When the mass ratio _SiO 2 _/ B 2 _{O 3} is decreased, the viscosity is decreased, the liquidus viscosity tends to decrease. Therefore, the lower limit range of the mass ratio SiO ₂ / B ₂ O ₃ is preferably 1 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, particularly 4 or more. Meanwhile, the mass ratio _SiO 2 _/ B 2 _{O 3} is increased, the devitrification resistance is decreased, the liquidus viscosity tends to decrease. Therefore, the upper limit range of the mass ratio SiO ₂ / B ₂ O ₃ is preferably 20 or less, 15 or less, 10 or less, 8 or less, particularly 6 or less. Here, “SiO ₂ / B ₂ O ₃ ” indicates a value obtained by dividing the content of SiO _{2 by} the content of B ₂ O ₃ .

When the mass ratio BaO / B ₂ O ₃ is regulated within a predetermined range, both a high refractive index and a high liquid phase viscosity can be achieved at a high level. Therefore, the lower limit range of the mass ratio BaO / B ₂ O ₃ is preferably 0.5 or more, 1.5 or more, 1.8 or more, 2 or more, 2.1 or more, particularly 2.3 or more, and the mass. The upper limit range of the ratio BaO / B ₂ O ₃ is preferably 5 or less, 4.5 or less, 4 or less, 3.5 or less, 3.2 or less, particularly 3 or less. Here, “BaO / B ₂ O ₃ ” indicates a value obtained by dividing the content of BaO by the content of B ₂ O ₃ .

TiO ₂ is a component that effectively increases the refractive index and ion exchange performance without increasing the batch cost. However, when the content of TiO ₂ is increased, the glass is colored or the devitrification resistance is easily lowered. Therefore, the content of TiO ₂ is preferably 1 to 10%, 2 to 8%, particularly 3 to 7%. Incidentally, the content of TiO ₂ increases, easily increases generation of Zr-containing devitrifying stones. Therefore, when it is desired to suppress the generation of Zr-containing devitrification beads, the content of TiO ₂ is preferably 6% or less, 5.5% or less, 5% or less, 4.5% or less, and particularly 4% or less.

  MgO is a component that increases the Young's modulus and decreases the high-temperature viscosity. However, when MgO is contained in a large amount, the refractive index tends to decrease or the liquidus temperature increases, and devitrification resistance increases. Tend to decrease, and the density and thermal expansion coefficient tend to increase. Therefore, the content of MgO is preferably 10% or less, 5% or less, 3% or less, 2% or less, particularly 1% or less.

  When the content of CaO increases, the density and thermal expansion coefficient tend to increase. When the content is excessive, the balance of the glass composition is lost and the devitrification resistance tends to decrease. Therefore, the content of CaO is preferably 12% or less, 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, particularly 3% or less. Note that when the content of CaO decreases, the refractive index, meltability, and Young's modulus tend to decrease. Therefore, the content of CaO is preferably 0.1% or more, 0.5% or more, 1% or more, particularly 2% or more.

When the mass ratio CaO / B ₂ O ₃ is regulated within a predetermined range, the devitrification resistance is easily improved. Therefore, the lower limit value of the mass ratio CaO / B ₂ O ₃ is preferably 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, particularly 0.3 or more, and the mass ratio CaO / The upper limit value of B ₂ O ₃ is preferably 1 or less, 0.8 or less, 0.7 or less, 0.6 or less, particularly 0.5 or less. Here, “CaO / B ₂ O ₃ ” is a value obtained by dividing the content of CaO by the content of B ₂ O ₃ .

  When the SrO content increases, the refractive index increases, but the density and thermal expansion coefficient tend to increase. On the other hand, when the SrO content is excessive, the balance of the glass composition is lacking and the devitrification resistance tends to be lowered. Moreover, it becomes difficult to give a high compressive stress to the glass surface by the ion exchange treatment. Therefore, the content of SrO is preferably 20% or less, 15% or less, 13% or less, and particularly 12% or less. When the SrO content is reduced, the refractive index and meltability are likely to be lowered, and in the composition system of the present invention, the viscosity in the vicinity of the liquidus temperature is lowered, making it difficult to obtain a high liquidus viscosity. Therefore, the content of SrO is preferably 0.1% or more, 1% or more, 3% or more, 5% or more, 7% or more, 9% or more, and particularly 10% or more.

  When the ZnO content increases, the density and thermal expansion coefficient increase, the component balance of the glass composition is lacking, the devitrification resistance decreases, the high temperature viscosity decreases too much, and a high liquid phase viscosity is ensured. It becomes difficult to do. Therefore, the content of ZnO is preferably 15% or less, 12% or less, 10% lower, 8% or less, 6% or less, particularly 4% or less. On the other hand, when the content of ZnO decreases, it becomes difficult to ensure a high liquid phase viscosity. Therefore, the content of ZnO is preferably 0.1% or more, 0.5% or more, 1% or more, more than 1%, 1.5% or more, 2% or more, 2.5% or more, particularly 3% or more. It is.

  The content of MgO + CaO + SrO + BaO + ZnO is preferably 10 to 50%, 20 to 47%, 25 to 45%, 30 to 43%, 35 to 41%, particularly 37 to 40%. In this way, high refractive index, devitrification resistance, meltability, low density, and low thermal expansion coefficient can be achieved at a high level. Here, “MgO + CaO + SrO + BaO + ZnO” is the total amount of MgO, CaO, SrO, BaO and ZnO.

When the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is regulated within a predetermined range, high refractive index, devitrification resistance, meltability, low density, and low thermal expansion coefficient can be achieved at a high level. Therefore, the lower limit value of the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is preferably 1 or more, 2.5 or more, 3.5 or more, particularly 4 or more, and the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ The upper limit value is preferably 7 or less, 6.5 or less, 6 or less, particularly 5.5 or less. Here, “(MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ ” refers to a value obtained by dividing the total amount of MgO, CaO, SrO, BaO and ZnO by the content of B ₂ O ₃ .

ZrO ₂ is a component that effectively increases the refractive index and ion exchange performance without increasing the batch cost. However, if the content of ZrO ₂ increases, Zr-containing devitrification will easily occur, and the liquidus temperature will tend to decrease. Therefore, the content of ZrO ₂ is preferably 0 to 10%, 0.01 to 10%, 0.1 to 5%, 0.5 to 4%, 1 to 3.5%, particularly 1.5 to 2%. .5%.

TiO ₂ and ZrO ₂ are components that effectively increase the refractive index and ion exchange performance without increasing the batch cost. However, when the content of TiO ₂ + ZrO ₂ is increased, the glass is colored or the devitrification resistance is easily lowered. Therefore, the content of TiO ₂ + ZrO ₂ is preferably 0 to 20%, 1 to 15%, 2 to 12%, 3 to 10%, 4 to 9%, particularly 5 to 6%. Here, “TiO ₂ + ZrO ₂ ” refers to the total amount of TiO ₂ and ZrO ₂ .

The content of P ₂ O ₅ is preferably 0 to 15%. P ₂ O ₅ is a component that forms a network and maintains the component balance of the glass composition. Therefore, the content of P ₂ O ₅ is preferably 0.01% or more, 0.1% or more, 0.4% or more, 0.6% or more, 0.8% or more, particularly 1% or more. However, when the content of P ₂ O ₅ increases, the component balance of the glass composition is lacking, and the devitrification resistance decreases. Therefore, the content of P ₂ O ₅ is preferably 15% or less, 10% or less, 6% or less, 4% or less, and particularly 2% or less.

  PbO is a component that lowers the high temperature viscosity, but it is preferable that it is not substantially contained from an environmental viewpoint. Here, “substantially does not contain” refers to the case where the content of the explicit component is 0.1% or less.

Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ is a component that increases the refractive index, but is a component that increases the batch cost. Therefore, the content of Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ is preferably 9% or less, 6% or less, 3% or less, 2% or less, 1.5 %, 1% or less, less than 1%, especially 0.5% or less is preferable, and it is desirable that it is not substantially contained. The contents of Bi ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ and WO ₃ are 9% or less, 6% or less, 3% or less, 2% or less, respectively. , 1.5%, 1% or less, less than 1%, particularly 0.5% or less, and it is desirable not to contain substantially. Here, “Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ ” means Bi ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Nb ₂ O ₅ , Ta _It refers to the total amount of ₂ O ₅ and WO ₃ .

As a fining agent, 0 to 3% of one or two 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 and F, in particular As ₂ O ₃ , are preferably not substantially contained from an environmental viewpoint. In particular, Sb ₂ O ₃ , SnO ₂ , SO ₃ and Cl are preferable as the fining agent. The content of Sb ₂ O ₃ is preferably 0 to 1%, 0.01 to 0.5%, particularly 0.05 to 0.4%. The content of SnO ₂ is preferably 0 to 1%, 0.01 to 0.5%, particularly 0.05 to 0.4%. The content of SnO ₂ + SO ₃ + Cl is preferably 0 to 1%, 0.001 to 1%, 0.01 to 0.5%, especially 0.01 to 0.3%. Here, “SnO ₂ + SO ₃ + Cl” refers to the total amount of SnO ₂ , SO ₃ and Cl.

  In addition to the above components, other components can be added. The amount added is preferably 10% or less, 5% or less, particularly 3% or less.

  The tempered glass of the present invention preferably has the following characteristics.

The density is preferably 5.0 g / cm ³ or less, 4.8 g / cm ³ or less, 4.5 g / cm ³ or less, 4.3 g / cm ³ or less, 3.7 g / cm ³ or less, particularly 3.5 g / cm ³ or less. cm ³ or less. In this way, the device can be reduced in weight. The “density” can be measured by a known Archimedes method.

The thermal expansion coefficient at 30 to 380 ° C. is preferably 30 × 10 ⁻⁷ / ° C. or more and 100 × 10 ⁻⁷ / ° C. or less, 40 × 10 ⁻⁷ / ° C. or more, and 90 × 10 ⁻⁷ / ° C. or less. It is 50 × 10 ⁻⁷ / ° C. or more and 85 × 10 ⁻⁷ / ° C. or less, particularly 60 × 10 ⁻⁷ / ° C. or more and 82 × 10 ⁻⁷ / ° C. or less. In recent years, in an organic EL device such as organic EL lighting and an organic EL display, and a dye-sensitized solar cell, the glass plate may be required to be flexible from the viewpoint of enhancing design elements. In order to increase the flexibility of the glass plate, it is necessary to reduce the thickness of the glass plate. In this case, if the thermal expansion coefficients of the glass plate and the transparent conductive film such as ITO, FTO, etc. are mismatched, the glass The board tends to warp. Therefore, if the thermal expansion coefficient at 30 to 380 ° C. is in the above range, such a situation can be easily prevented. The “thermal expansion coefficient at 30 to 380 ° C.” can be measured with a dilatometer or the like.

  The strain point is preferably 500 ° C. or higher, 540 ° C. or higher, 560 ° C. or higher, particularly 580 ° C. or higher. If it does in this way, it will become difficult to heat-shrink a glass plate by the high temperature heat processing in the manufacturing process of a device. “Strain point” refers to a value measured based on the method described in ASTM C336-71.

The temperature at 10 ^2.0 dPa · s is preferably 1000 ° C. or higher, 1100 ° C. or higher, particularly 1130 ° C. or higher. In this way, since the molding temperature can be increased, devitrification during molding can be easily prevented.

The liquidus temperature is preferably 1200 ° C. or lower, 1150 ° C. or lower, 1130 ° C. or lower, 1100 ° C. or lower, 1050 ° C. or lower, 1030 ° C. or lower, particularly 1000 ° C. or lower. The liquid phase viscosity is preferably 10 ^3.0 dPa · s or more, 10 ^3.5 dPa · s or more, 10 ^4.0 dPa · s or more, 10 ^4.2 dPa · s or more, 10 ^4.6 dPa or more. S or more, 10 ^5.0 dPa · s or more, particularly 10 ^5.2 dPa · s or more. If it does in this way, it will become difficult to devitrify glass at the time of shaping | molding, and it will become easy to shape | mold a glass plate by the float method etc. Here, the “liquid phase temperature” is obtained by passing the standard sieve 30 mesh (500 μm) and putting the glass powder remaining in 50 mesh (300 μm) into a platinum boat and holding it in a temperature gradient furnace for 24 hours to precipitate crystals. Refers to the value of the measured temperature. “Liquid phase viscosity” refers to a value obtained by measuring the viscosity of glass at the liquid phase temperature by a platinum ball pulling method.

  The tempered glass of the present invention preferably has a flat plate shape, and the thickness thereof is preferably 1.5 mm or less, 1.3 mm or less, 1.1 mm or less, 0.8 mm or less, 0.6 mm or less, 0.5 mm. Below, it is 0.3 mm or less, 0.2 mm or less, especially 0.1 mm or less. The smaller the plate thickness, the higher the flexibility and the easier it is to produce a lighting device with excellent design. However, when the plate thickness is extremely small, the glass plate tends to break. Furthermore, if the plate thickness becomes extremely small, the internal tensile stress becomes excessive, and the glass plate is liable to self-break. Therefore, the plate thickness is preferably 10 μm or more, particularly 30 μm or more.

  When the tempered glass of the present invention has a flat plate shape, at least one surface is preferably unpolished. 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 glass surface in a post-molding process such as a polishing process. Therefore, if the glass surface is unpolished, the original mechanical strength of the glass is hardly lost, and the glass plate is difficult to break. Further, if the glass surface is unpolished, the polishing step can be omitted, so that the manufacturing cost of the glass plate can be reduced.

  In the tempered glass of the present invention, the surface roughness Ra of at least one surface (however, the effective surface) is preferably 10 mm or less, 5 mm or less, 3 mm or less, particularly 2 mm or less. When the surface roughness Ra is larger than 10 mm, the quality of ITO formed on the surface is lowered and it is difficult to obtain uniform light emission. Here, “surface roughness Ra” refers to a value measured by a method based on JIS B0601: 2001.

  The tempered glass of the present invention preferably has a roughened surface formed on one surface. The surface roughness Ra of the roughened surface is preferably 10 mm or more, 20 mm or more, 30 mm or more, particularly 50 mm or more. If the roughened surface is on the side in contact with air such as organic EL lighting, the roughened surface has a non-reflective structure, so that the light generated in the organic light emitting layer is difficult to return to the organic light emitting layer. The light extraction efficiency can be increased.

  The time for forming the roughened surface may be after the ion exchange treatment, but is preferably before the ion exchange treatment from the viewpoint of mechanical strength. What is necessary is just to adjust the space | interval and depth of the uneven | corrugated shape of a roughened surface, considering a refractive index.

  As a method for forming the roughened surface, a sandblasting process, an etching process using an HF solution, or the like is preferable from the viewpoint of processing efficiency.

  A roughened surface may be formed on one surface by thermal processing such as repressing. In this way, an accurate non-reflective structure can be formed on one surface.

If roughening treatment is performed by an atmospheric pressure plasma process, a uniform roughened surface can be formed on one surface, and the surface state of the other surface can be maintained in a smooth state. Moreover, it is preferable to use a gas containing F (for example, SF ₆ , CF ₄ ) as a source of the atmospheric pressure plasma process. In this way, since plasma containing HF gas is generated, the efficiency of the roughening treatment is improved.

  In addition, when forming a non-reflective structure on the surface at the time of shaping | molding, the same effect can be enjoyed even if it does not roughen. Moreover, you may affix the light-scattering film which has an uneven | corrugated shape on one surface.

  Next, a method for producing the tempered glass of the present invention will be exemplified. First, glass raw materials are prepared so as to obtain a desired glass composition, and a glass batch is prepared. Next, the glass batch is melted and refined, and then formed into a desired shape. Thereafter, it is processed into a desired shape.

  The tempered glass of the present invention is preferably formed by a float process. In this way, a glass plate having a good surface quality can be manufactured at low cost and in large quantities. Further, it becomes easy to increase the size of the glass plate.

  Moreover, it is preferable that the glass for reinforcement | strengthening of this invention is shape | molded by the overflow downdraw method. In this way, it is possible to manufacture a glass plate that is unpolished and has good surface quality at a low cost and in large quantities. Further, it becomes easy to increase the size and thickness of the glass plate.

  Furthermore, the tempered glass of the present invention is preferably formed by a roll-out method or an updraw method. If it does in this way, it will become easy to control devitrification at the time of fabrication.

  Next, the tempered glass can be produced by subjecting the obtained tempered glass to an ion exchange treatment. The time for cutting the tempered glass to a predetermined size may be before the ion exchange treatment or after the ion exchange treatment.

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 a KNO ₃ molten salt at 390 to 550 ° C. for 1 to 24 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 glass surface.

  Hereinafter, based on an Example, this invention is demonstrated in detail. The following examples are merely illustrative. The present invention is not limited to the following examples.

  First, after preparing a glass raw material so that it might become a glass composition of Table 1, the obtained glass batch was supplied to the glass melting furnace, and it melted at 1300-1400 degreeC for 7 hours. Next, the obtained molten glass was poured onto a carbon plate and formed into a flat plate shape, and then a predetermined slow cooling treatment was performed. Finally, various properties of the obtained reinforcing glass plate were evaluated.

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

  Thermal expansion coefficient (alpha) is the value which measured the average thermal expansion coefficient in 30-380 degreeC using the dilatometer. As a measurement sample, a cylindrical sample having a diameter of 5 mm × 20 mm (the end surface is R-processed) was used.

  The strain point Ps is a value measured based on the method described in ASTM C336-71. In addition, heat resistance becomes high, so that the strain point Ps is high.

  The annealing point Ta and the softening point Ts are values measured based on the method described in ASTM C338-93.

The temperatures at high temperature viscosities of 10 ^4.0 dPa · s, 10 ^3.0 dPa · s, 10 ^2.5 dPa · s, and 10 ^2.0 dPa · s are values measured by the platinum ball pulling method. In addition, meltability and a moldability improve, so that these temperatures are low.

  The liquid phase temperature TL passes through a standard sieve 30 mesh (500 μm), and the glass powder remaining in 50 mesh (300 μm) is placed in a platinum boat and held in a temperature gradient furnace for 24 hours to measure the temperature at which crystals precipitate. It is the value. The liquid phase viscosity log ηTL is a value obtained by measuring the viscosity of the glass at the liquid phase temperature by a platinum ball pulling method. The higher the liquidus viscosity and the lower the liquidus temperature, the better the devitrification resistance and moldability.

Refractive index _{n d} is a value measured using a refractive index measuring apparatus KPR-2000 of Shimadzu Corporation, which is a measure of hydrogen lamp d-line (wavelength 587.6 nm). In the measurement, after preparing a rectangular parallelepiped sample of 25 mm × 25 mm × about 3 mm, it is gradually cooled at a cooling rate such that the temperature range from (Ta + 30 ° C.) to (Ps−50 ° C.) is 0.1 ° C./min. Treatment was followed by infiltration of the immersion liquid with matching refractive index between the glasses.

Next, sample No. After performing optical polishing on both surfaces of the reinforcing glass plates according to 1 to 4, ion exchange treatment was performed by immersing in 430 ° C. KNO ₃ molten salt for 24 hours. After the ion exchange treatment, the surface of each sample was washed to obtain tempered glass.

  Subsequently, sample No. About the tempered glass board concerning 2, crack incidence was evaluated. That is, a tempered glass plate was placed on the stage of a Vickers hardness tester, and a diamond-shaped diamond indenter was pressed against the surface of the tempered glass plate with a load of 30 g for 15 seconds. Then, the number of cracks generated from the four corners of the indentation was counted by 15 seconds after unloading, and the ratio with respect to the maximum number of cracks (4) that could be generated was determined and used as the crack generation rate. The crack occurrence rate was measured 10 times under the same load, and the average value was obtained. As a result, the crack occurrence rate of the unstrengthened glass plate (strengthening glass plate) was 67.5%, but the crack occurrence rate of the tempered glass plate was 35%.

  Sample No. Also about the tempered glass board concerning 1, 3, and 4, it is estimated that a crack generation rate falls by an ion exchange process.

Claims (6)

In tempered glass having a compressive stress layer on the surface,
Compressive stress layer is formed by ion exchange treatment, tempered glass having a refractive index n _d is equal to or is from 1.55 to 2.00. 2. The tempered glass according to claim 1, wherein the glass composition contains, by mass%, SiO ₂ 20 to 70%, Li ₂ O + Na ₂ O + K ₂ O 0.1 to 30%, BaO 4 to 40%. . The tempered glass according to claim 1, wherein 1 to 10% by mass of TiO ₂ is contained in the glass composition.   It uses for an illuminating device, Tempered glass in any one of Claims 1-3 characterized by the above-mentioned.   It uses for organic electroluminescent illumination, Tempered glass in any one of Claims 1-4 characterized by the above-mentioned. A tempered glass for ion exchange treatment,
Reinforced glass having a refractive index _{n d} is equal to or is from 1.55 to 2.0.