JP6435610B2 - High refractive index glass - Google Patents

Description

  The present invention relates to a high refractive index glass, for example, an organic EL device, and particularly to a high refractive index glass suitable for 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.

  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 contain a large amount of expensive heavy metals and have a low liquid phase viscosity, so that they are difficult to form into a flat plate shape and are not suitable for mass production.

  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 a high liquidus viscosity without containing a large amount of expensive heavy metals.

As a result of intensive studies, the inventor has found that the above technical problem can be solved by regulating the glass composition range and the glass characteristics to a predetermined range, and proposes the present invention. That is, the high refractive index glass of the present invention is, as a glass composition, by mass%, SiO ₂ 26 to 70%, B ₂ O ₃ 4.5 to 35%, MgO + CaO + SrO + BaO + ZnO 10 to 48%, BaO 10 to 31%, LiO _{2 O + Na 2 O + K} 2 contain O 0-.29%, and a refractive index _{n d} is equal to or is from 1.51 to 2.0. Here, “MgO + CaO + SrO + BaO + ZnO” is the total amount of MgO, CaO, SrO, BaO and ZnO. “Li ₂ O + Na ₂ O + K ₂ O” is the total amount of Li ₂ O, Na ₂ O and K ₂ O. “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.

Secondly, in the high refractive index glass of the present invention, the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 30.5 to 80% by mass. By doing so, since the components forming the glass network structure increase, it becomes easy to form into a flat plate shape. Here, “SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ” is the total amount of SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ .

Third, the high refractive index glass of the present invention preferably has a mass ratio SiO ₂ / B ₂ O ₃ of 1.2 to 20. If it does in this way, devitrification resistance will improve and a liquid phase viscosity can be raised.

Fourthly, the high refractive index glass of the present invention is substantially free of PbO, and 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 9 mass. % Or less is preferable. In this way, it is possible to reduce the batch cost while considering environmental requirements. Here, “substantially free of” means that the inclusion of an explicit component is avoided as much as possible, but the inclusion of an impurity level is allowed, and specifically, the content of the explicit component Is less than 0.5% (preferably less than 0.1%, especially less than 0.05%). “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 ₂ Refers to the total amount of O ₅ and WO ₃ .

Fifth, it is preferable that the high refractive index glass of the present invention does not substantially contain an alkali metal oxide. In this way, it is not necessary to form a passivation film such as a SiO ₂ film, and the manufacturing cost can be reduced.

Sixth, the high refractive index glass of the present invention preferably has a liquidus viscosity of 10 ^3.0 dPa · s or more. Here, “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. “Liquid phase temperature” refers to the temperature at which crystals precipitate 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. It is a measured value

  Seventh, the high refractive index glass of the present invention is preferably formed by a float process.

  Eighth, the high refractive index glass of the present invention is preferably formed by a roll-out method or an updraw method.

  Ninthly, the lighting device of the present invention includes the above-described high refractive index glass.

  Tenth, the organic EL lighting of the present invention is characterized by comprising the above-described high refractive index glass.

  The reason why the content range of each component is limited as described above in the high refractive index glass of the present invention 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 26 to 70%. When the content of SiO ₂ 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 is preferably 26% 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, 53% or less, 51% or less, 48% or less, 45% or less, particularly 43% or less.

The content of B ₂ O ₃ is preferably 4.5 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, 30% or less, 25% or less, 20% or less, 18% or less, and particularly 16% 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 4.5% or more, 6% or more, 8% or more, 9% or more, particularly 10% or more.

Weight ratio _SiO 2 _/ B 2 _{O 3} is 1.2 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 value of the mass ratio SiO ₂ / B ₂ O ₃ is preferably 1.2 or more, 1.4 or more, 1.6 or more, 1.8 or more, 2.0 or more, 2.2 or more. 4 or more, particularly 2.5 or more. On the other hand, if 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 of the mass ratio SiO ₂ / B ₂ O ₃ is preferably 20 or less, 15 or less, 10 or less, 5 or less, 4.0 or less, 3.8 or less, 3.6 or less, 3.4 or less, 3.2 or less, particularly 3.0 or less.

  The content of MgO + CaO + SrO + BaO + ZnO is preferably 10 to 48%, 20 to 47%, 25 to 46%, 30 to 45%, 32 to 42%, particularly 34 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. In addition, when there is too much content of MgO + CaO + SrO + BaO + ZnO, there exists a possibility that a density and a thermal expansion coefficient may rise unduly, and when there is too little content of MgO + CaO + SrO + BaO + ZnO, a refractive index, devitrification resistance, and a meltability will fall easily.

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, 1.5 or more, 1.8 or more, particularly 2 or more, and the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ The upper limit is preferably 6 or less, 5 or less, 4.5 or less, particularly 4 or less. If the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is too large, the density and the thermal expansion coefficient may be unreasonably increased. If the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is too small, refraction will occur. Rate, devitrification resistance, and meltability tend to decrease.

  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 of the mass ratio CaO / B ₂ O ₃ is preferably 1 or more, 2 or more, 2.5 or more, 3 or more, particularly 3.5 or more, and the upper limit of the mass ratio CaO / B ₂ O ₃ . The value is preferably 10 or less, 8 or less, 7 or less, 6 or less, in particular 5.5 or less.

  When the SrO content increases, the refractive index increases and the viscosity near the liquidus temperature can be increased, 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. Therefore, the content of SrO is preferably 20% or less, 15% or less, 13% or less, and particularly 12% or less. In addition, when the content of SrO decreases, the refractive index and meltability tend to decrease. Therefore, the content of SrO is preferably 0.1% or more, 1% or more, 3% or more, 5% or more, 7% or more, 8% or more, and particularly 10% or more.

  BaO is a component that increases the refractive index of alkaline earth metal oxides without extremely reducing the viscosity of the glass. 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, the balance of a glass composition will be missing and devitrification resistance will fall easily. Therefore, the content of BaO is preferably 31% or less, 28% or less, 26% or less, 24% or less, 22% or less, particularly 20% or less. However, 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 content of BaO is preferably 10% or more, 11% or more, 12% or more, 13% or more, 14% or more, 15% or more, particularly 16% or more.

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 value of the mass ratio BaO / B ₂ O ₃ is preferably 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, particularly 1 or more, and the mass The upper limit 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 or less, particularly 2.5 or less. If the mass ratio BaO / B ₂ O ₃ is too large, the liquid phase viscosity tends to decrease, and if the mass ratio BaO / B ₂ O ₃ content is too small, the refractive index tends to decrease.

  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. However, 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.

Li ₂ O + Na ₂ O + K ₂ O is a component that lowers the viscosity of the glass and adjusts the coefficient of thermal expansion. However, when introduced in a large amount, the viscosity of the glass decreases too much, resulting in a high liquidus viscosity. It becomes difficult to secure. Depending on the application, it is necessary to form a passivation film such as a SiO ₂ film on the surface of the glass. Therefore, the content of Li ₂ O + Na ₂ O + K ₂ O is preferably 0.29% or less, 0.20% or less, 0.10% or less, particularly 0.05% or less, and not substantially contained. desirable. The content of Li ₂ O, Na ₂ O, and K ₂ O is preferably 0.29% or less, 0.20% or less, 0.10% or less, particularly 0.05% or less for each component. It is desirable not to contain.

  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. Incidentally, the content of Al ₂ O ₃ is reduced, lacks the balance of the glass composition, the glass is liable to devitrify reversed. 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 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, 50% or more, particularly 54% or more. is there. On the other hand, when the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ increases, the refractive index, meltability, and moldability tend to decrease. 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, 62% or less, 61% or less, particularly 60% 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.

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 content of Bi ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and WO ₃ is 9% or less, 6% or less, 3% or less, 2 for each component. % Or less, 1.5%, 1% or less, less than 1%, particularly 0.5% or less, and it is desirable not to contain substantially.

TiO ₂ is a component that effectively increases the refractive index 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 0.01 to 15%, 0.1 to 15%, 1 to 12%, 2 to 10%, 3 to 9%, particularly 3 to 8%. 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.

ZrO ₂ is a component that effectively increases the refractive index without increasing the batch cost. However, when the content of ZrO ₂ increases, the liquidus temperature tends to decrease. Therefore, the content of ZrO ₂ is preferably 0 to 10%, 0.01 to 10%, 0.1 to 8%, 0.5 to 7%, 1 to 6.5%, particularly 1.5 to 5%. %. In addition, when it is desired to suppress the generation of Zr-containing devitrification beads, the content of ZrO ₂ is preferably 5% or less, 4% or less, 3.5% or less, 3% or less, particularly 2.5% or less.

When the content of P ₂ O ₅ increases, the component balance of the glass composition is lacking and the devitrification resistance is lowered. Therefore, the content of P ₂ O ₅ is preferably 15% or less, 10% or less, 6% or less, and particularly 4% or less.

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%, 5% or less, particularly 3% or less.

  The high refractive index glass of the present invention preferably has the following characteristics.

Refractive index _{n d} is preferably 1.51 or more, 1.55 or more, 1.58 or more, 1.60 or more, particularly 1.62 or more. When the refractive index _{n d} is less than 1.51, it might become caught efficiently light by reflection ITO- glass interface. On the other hand, when the refractive index _nd increases, the balance of the glass composition is lost, and the devitrification resistance is likely to decrease. Moreover, when the refractive index _nd 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. Incidentally, introduction a large amount of heavy metal in the glass composition, after securing the devitrification resistance, but it is possible to increase the refractive index n _d, in this case, batch cost is soaring. Therefore, the refractive index _nd is preferably 2.0 or less, 1.68 or less, 1.67 or less, 1.66 or less, particularly 1.65 or less.

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. to 100 × 10 ⁻⁷ / ° C., 40 × 10 ⁻⁷ / ° C. to 90 × 10 ⁻⁷ / ° C., 50 × 10 ⁻⁷ / ℃ ~85 × ^{10 -7} / ℃, in particular ^{60 × 10 -7 / ℃ ~70 ×} 10 -7 / ℃. 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 flexibility, 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 or FTO are mismatched, the glass plate warps. It becomes easy. 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, 580 ° C. or higher, particularly 590 ° 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. Further, 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, particularly 10 ^4.5 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.

  The high refractive index glass of the present invention preferably has a flat plate shape, and the plate thickness 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, 0.00 mm or less. 5 mm or less, 0.3 mm or less, 0.2 mm or less, particularly 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, but the glass is more likely to break when the plate thickness is extremely small. Therefore, the plate thickness is preferably 10 μm or more, particularly 30 μm or more.

  When the high refractive index 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 is generated on the surface in a post-molding process such as a polishing process. Therefore, if the surface is not polished, the original mechanical strength of the glass is hardly lost, and the glass plate is difficult to break. Further, if the surface is not polished, the polishing step can be omitted, and the manufacturing cost of the glass plate can be reduced.

  In the high refractive index 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 high refractive index glass of the present invention is preferably subjected to a surface roughening treatment on one surface by HF etching, sandblasting or the like. 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 the 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. As a result, the light extraction efficiency can be increased.

  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. What is necessary is just to adjust the space | interval and depth of an uneven | corrugated shape, considering a refractive index.

If roughening 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.

  The high refractive index glass of the present invention preferably has a light scattering function by phase separation. If it does in this way, it will become easy to take out the light in a glass plate in the air, without forming a roughening process surface in one surface or sticking a light-scattering film. In the glass plate manufacturing process, the phase separation may occur at any time during melting, molding, and slow cooling, and the phase separation may be performed by separately heat-treating the glass that has not undergone phase separation. May be generated.

  Next, a method for producing the high refractive index 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 high refractive index 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.

  The high refractive index 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.

  Further, the high refractive index glass of the present invention is preferably formed by an overflow down draw 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.

  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, 2, 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 characteristics of the obtained 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, it is excellent in meltability and moldability, 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. Further, the liquid phase viscosity log ηTL indicates 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.

As apparent from Tables 1 and 2, Sample No. 1-25, even though it does not contain expensive heavy metals, refractive index n _d is high, the devitrification resistance was good.

Claims (10)

As a glass composition, in _{mass%, SiO 2 30~ 51%,} B 2 O 3 10.1~ 25%, Al 2 O 3 0~ 8%, MgO + CaO + SrO + BaO + ZnO 25 ~48%, ZnO 1 ~ 12%, CaO 1~ _{12%, SrO 5~20%, BaO} 13 ~31%, wherein the _{Li 2 O + Na 2 O +} K 2 contain O from 0 to .29%, and a refractive index _{n d} is 1.6 to 2.0 High refractive index glass. The high refractive index glass according to claim 1, wherein the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is 42 to 65 % by mass. High refractive index glass according to claim 1 or 2 weight ratio _SiO 2 _/ B 2 _{O 3} is characterized in that it is a 1.2-5. Substantially free of PbO, and _{Bi 2 O 3 + La 2 O} 3 + Gd 2 O 3 + Nb 2 O 5 + content of Ta ₂ O 5 + WO ₃ is equal to or less than 9 wt% claim 1 4. The high refractive index glass according to any one of 3.   The high refractive index glass according to any one of claims 1 to 4, which does not substantially contain an alkali metal oxide. Liquid phase viscosity is 10 < ^3.0 > dPa * s or more, The high refractive index glass in any one of Claims 1-5 characterized by the above-mentioned.   The high refractive index glass according to claim 1, wherein the high refractive index glass is formed by a float process.   The high refractive index glass according to any one of claims 1 to 6, which is formed by a rollout method or an updraw method.   An illumination device comprising the high refractive index glass according to claim 1.   An organic EL illumination comprising the high refractive index glass according to claim 1.