DE112014002123T5 - Glass with high refractive index - Google Patents

Abstract

A high refractive index glass of the present invention contains as a glass composition, in mass percent, 25% to 60% of MgO + CaO + SrO + BaO + ZnO, 0% to 5% of CaO, and 3% to 20% of TiO 2 + ZrO 2, and has a refractive index nd of 1.51 to 1.7.

Description

Technical area

The present invention relates to a high-refractive-index glass, and more particularly to a high-refractive-index glass useful, for example, in an OLED device, particularly an OLED lighting device.

State of the art

In recent years, displays and lighting devices using an OLED light-emitting element have been receiving increasing attention. The OLED devices have a structure in which an organic light-emitting element is enclosed by glass plates on which a transparent conductive film such as an ITO film is formed. With this structure, when an electric current flows through the organic light-emitting element, holes and electrons are combined in the organic light-emitting element to emit light. The emitted light penetrates through the transparent conductive film, such as an ITO film, into the glass plate and is emitted with repeated reflection in the glass plate.

CITATION LIST

• Patent Literature 1: JP 2007-186407 A

Summary of the invention

Technical problem

The organic light-emitting element has a refractive index n _d of 1.8 to 1.9, and ITO has a refractive index n _d of 1.9 to 2.0. On the other hand, the glass plate usually has a refractive index n _d of about 1.5.

Consequently, a conventional OLED device has the problem that a difference in refractive index between the glass plate and the ITO film at its interface results in high reflection, and therefore the light emitted from the organic light-emitting element can not be efficiently extracted.

In addition, high refractive index glasses can be used in the field of optical glasses (for example, see Patent Literature 1). However, the high refractive index glass contains a large amount of expensive heavy metals and has a low liquidus viscosity. Therefore, the high refractive index glass is difficult to form into a flat glass shape, and therefore, it is not suitable for mass production.

In view of the above circumstances, the present invention has been made, and a technical object of the present invention is to provide a high refractive index glass having a high liquidus viscosity even if it does not contain a large amount of expensive heavy metals.

the solution of the problem

The inventors of the present invention have conducted detailed studies, and have consequently found that the above-mentioned technical object can be achieved by restricting glass composition and glass properties within predetermined ranges. This finding is proposed as the following first to fourth invention.

The high refractive index glass according to the first invention comprises as a glass composition, in mass percentage, 25% to 60% of MgO + CaO + SrO + BaO + ZnO, 0% to 5% of CaO and 3% to 20% of TiO ₂ + ZrO ₂ , and has a refractive index n _d of 1.51 to 2.0. Herein, the term "MgO + CaO + SrO + BaO + ZnO" refers to the total amount of MgO, CaO, SrO, BaO and ZnO. The term "TiO ₂ + ZrO ₂ " refers to the total amount of TiO ₂ and ZrO ₂ .

The "refractive index n _d " is a value at the d-line (wavelength: 587.6 nm) of a hydrogen lamp and can be measured with a refractometer. For example, the refractive index n _d may be annealed at a cooling rate of 0.1 ° C./min in a temperature range by preparing specimens each having a 25 mm by 25 mm by 3 mm rectangular parallelogram shape from (upper cooling point Ta + 30 ° C) to (lower cooling point - 50 ° C), and then measuring the refractive index with a refractometer KPR-2000, manufactured by Shimadzu Corporation, in a state where an immersion liquid having a refractive index coinciding with which matches the samples, is inserted between glasses.

In addition, a high refractive index glass according to the second invention comprises as glass composition, in mass percentage, 30% to 80% of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ , 0.1% to 20% of B ₂ O ₃ + ZnO, and 3% to 20% of TiO ₂ + ZrO ₂ , and has a refractive index n _d of 1.51 to 2.0. Herein, the term "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 . The term "B ₂ O ₃ + ZnO" refers to the total amount of B ₂ O ₃ and ZnO. The term "TiO ₂ + ZrO ₂ " refers to the total amount of TiO ₂ and ZrO ₂ . The term "refractive index n _d " is as described in the first invention.

Further, the high refractive index glass according to the third invention comprises as the glass composition 3 mass% to 20 mass% of TiO ₂ + ZrO ₂ , has a mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO of 2 to 10, and has a refractive index n _d from 1.51 to 2.0. Herein, the term "TiO ₂ + ZrO ₂ " refers to the total amount of TiO ₂ and ZrO ₂ . The term "MgO + CaO + SrO + BaO + ZnO" refers to the total amount of MgO, CaO, SrO, BaO and ZnO. The expression "(MgO + CaO + SrO + BaO + ZnO) / CaO" refers to a value obtained by dividing the content of MgO + CaO + SrO + BaO + ZnO by the content of CaO. The term "refractive index n _d " is as described in the first invention.

A high refractive index glass according to the fourth invention comprises as the glass composition, in mass percentage, 26% to 70% of SiO ₂ , 4.5% to 35% of B ₂ O ₃ , 10% to 48% of MgO + CaO + SrO + BaO + ZnO, 10% to 31% of BaO and 0% to 0.29% of Li ₂ O + Na ₂ O + K ₂ O, and has a refractive index n _d of 1.51 to 2.0. Herein, the term "MgO + CaO + SrO + BaO + ZnO" refers to the total amount of MgO, CaO, SrO, BaO and ZnO. The term "Li ₂ O + Na ₂ O + K ₂ O" refers to the total amount of Li ₂ O, Na ₂ O and K ₂ O. The term "refractive index n _d " is as described in the first invention.

It is preferable that the high refractive index glass according to the third invention comprises more than 5.0 mass% of CaO. This makes it easy to increase the meltability and the Young's modulus while maintaining the refractive index.

It is preferable that the high refractive index glass according to the first to fourth invention each comprises 0.1 mass% to 15 mass% of B ₂ O ₃ . Thus, the density and the liquidus temperature is easily reduced.

It is preferable that the high refractive index glass according to the first to fourth invention each comprises 0.01 mass% to 10 mass% of ZrO ₂ . Thus, the liquidus viscosity can be increased by raising the temperature near the liquidus temperature while increasing the refractive index.

It is preferable that the high-refractive-index glass according to the first to fourth invention comprises 0.01% by mass to 15% by mass of TiO ₂ , respectively. Thus, the refractive index can be increased.

It is preferable that the high-refractive-index glass according to the first to fourth invention is each substantially free of PbO and each has a content of Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO _{3 has} 9 mass% or less. Thus, the batch costs can be reduced taking into account the environmental requirements. Herein, the key message of the term "substantially free of" is that the admixture of a particular component is avoided as much as possible, but the contamination level admixture is allowed. To be specific, the expression refers to the case that the content of the specific component is less than 0.5% (preferably less than 0.1%).

It is preferable that the high-refractive-index glass according to the first to fourth invention each comprises 0.1 mass% to 15 mass% of ZnO. This makes it easy to reduce the liquidus temperature.

It is preferable that the high refractive index glass according to the first to fourth invention is each substantially free of an alkali metal oxide. Thus, it becomes unnecessary to form a passivation film such as a SiO ₂ film, which can reduce the manufacturing cost. Herein, the term "alkali metal oxide" includes Li ₂ O, Na ₂ O and K ₂ O.

It is preferable that the high refractive index glass according to the first to fourth invention each have a liquidus viscosity of 10 ^3.0 dPa · s or more. Thus, the glass can be easily formed by an overflow-down-draw process in a glass plate. Herein, the term "liquidus viscosity" refers to a value obtained by measuring the viscosity at its liquidus temperature by a platinum ball pull-up method. The term "liquidus temperature" refers to a value obtained by measuring a temperature at which crystals of the glass deposit after glass powder passing through a standard 30 mesh screen (500 μm) and running on a 50 μm screen. Mesh screen (300 microns) left, placed in a platinum boat and kept in a gradient oven for 24 hours.

It is preferable that the high refractive index glass according to the first to fourth invention each has a plate shape and at least one surface of each high refractive index glass has a surface roughness Ra of 10 Å or less. Herein, the term "surface roughness Ra" refers to a value obtained by measuring using a method according to JIS B0601: 2001.

It is preferable that the high refractive index glass according to the first to fourth invention is each formed by an overflow-down draw method.

The above-mentioned high refractive index glass according to the first to fourth invention may be used respectively in a lighting device, an OLED lighting device, and an OLED display.

Description of the embodiments

First invention

A high refractive index glass according to the first invention contains, as the weight composition, 25% to 60% of MgO + CaO + SrO + BaO + ZnO, 0% to 5% of CaO and 3% to 20%, and TiO ₂ + ZrO ₂ . The following describes the reasons why the content ranges of the components are limited as described above. Note that in the following description of content ranges, the term "%" refers to mass percent unless otherwise specified.

The content of MgO + CaO + SrO + BaO + ZnO is from 25% to 60%, preferably from 30% to 55%, from 32% to 50%, from 34% to 49%, from 36% to 47%, especially preferably from 38% to 45%. At the same time, high refractive index, devitrification resistance, fusibility, low density and low coefficient of thermal expansion can be achieved at a high level. Note that if the content of MgO + CaO + SrO + BaO + ZnO is excessively large, there is a risk that the density and coefficient of thermal expansion may increase disproportionately. When the content of MgO + CaO + SrO + BaO + ZnO is extremely small, the refractive index, the devitrification resistance and the meltability are lowered.

As the content of MgO + CaO increases, the glass composition loses its balance and the devitrification resistance becomes lower. Therefore, the content of MgO + CaO is preferably 12% or less, 10% or less, 8% or less, 7% or less, 6% or less, 4.6% or less, 4% or less, 3.5% or less, 3% or less, more preferably 2.5% or less. Note that the fusibility decreases as the content of MgO + CaO decreases. Therefore, the content of MgO + CaO is preferably 0.1% or more, 0.5% or more, 1% or more, particularly preferably 2% or more. Herein, the term "MgO + CaO" refers to the total amount of MgO and CaO.

MgO is a component that increases the Young's modulus, and is a component that lowers the viscosity at high temperature. However, if MgO is contained in a large amount, it decreases the refractive index and the liquidus temperature increase, with the result that the devitrification resistance decreases and the density and coefficient of thermal expansion increase. Therefore, the content of MgO is preferably 10% or less, 5% or less, 3% or less, 2% or less, 1.5% or less, 1% or less, particularly preferably 0.5% or less.

The content of CaO is from 0% to 5%. As the content of CaO increases, the density and coefficient of thermal expansion increase. If the content is more than 5%, the glass composition loses its balance and the devitrification resistance becomes lower. Therefore, the content of CaO is preferably 4.5% or less, 4% or less, 3.5% or less, 3% or less, particularly preferably 2.5% or less. Note that as the content of CaO decreases, the refractive index, meltability and Young's modulus decrease. Therefore, the content of CaO is preferably 0.1% or more, 0.5% or more, 1% or more, particularly preferably 2% or more.

The mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO is preferably 8.5 or more, 10 or more, 11.4 or more, 12 or more, from 13 to 25, from 13.5 to 21, of 14 to 19, more preferably 14.5 to 17. Thus, the refractive index and the devitrification are easily increased simultaneously. Note that the expression "(MgO + CaO + SrO + BaO + ZnO) / CaO" refers to a value obtained by dividing the content of MgO + CaO + SrO + BaO + ZnO by the content of CaO.

As the content of SrO increases, the refractive index becomes high and the viscosity around the liquidus temperature can be increased. However, the density and coefficient of thermal expansion increase. Further, if the content of SrO excessively increases, the glass composition loses its balance and the devitrification resistance becomes lower. Therefore, the content of SrO is preferably 20% or less, 15% or less, 13% or less, 12% or less, particularly preferably 11% or less. Note that the refractive index and the meltability decrease as the content of SrO decreases. 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, particularly preferably 10% or more.

Among the alkaline earth metal oxides, BaO is a component which increases the refractive index without extremely lowering the viscosity of the glass. However, as the content of BaO increases, the density and coefficient of thermal expansion tend to increase, and the liquidus viscosity becomes lower. Further, when the content of BaO is excessively increased, the glass composition loses balance and the devitrification resistance decreases. The content of BaO is therefore preferably 50% or less, 45% or less, 40% or less, 35% or less, 32% or less, 30% or less, particularly preferably 28% or less. Note that it is difficult to obtain a desired refractive index, and it is difficult to ensure a high liquidus viscosity as the content of BaO decreases. The content of BaO is therefore preferably 0.1% or more, 1% or more, 5% or more, 10% or more, 12% or more, 15% or more, 17% or more, 20% or more, 23 % or more, more preferably 25% or more.

As the content of ZnO increases, the density and coefficient of thermal expansion increase, and the glass composition loses its component balance, with the result that the devitrification strength decreases and the viscosity at high temperature excessively low, making it difficult to ensure a high liquidus viscosity , Therefore, the content of ZnO is preferably 15% or less, 10% or less, 6% or less, 4% or less, 2% or less, 1% or less, 0.5% or less, particularly preferably 0.1%. Or less. Note that it is difficult to ensure a high liquidus viscosity when the content of ZnO decreases. The content of ZnO is therefore preferably 0.1% or more, 0.1% or more, 1% or more, more than 1%, 1.5% or more, 2% or more, 2.5% or more, more preferably 3% or more.

TiO ₂ + ZrO ₂ is a component that effectively increases the refractive index without causing the batch cost to swell. However, as the content of TiO ₂ + ZrO ₂ increases, the devitrification resistance decreases. The content of TiO ₂ + ZrO ₂ is therefore from 3% to 20%, preferably from 4% to 15%, from 5% to 12%, from 5.5% to 11%, from 6% to 10%, particularly preferably from 6, 5% to 9%. Note that, in the case where the generation of Zr-containing devitrification bricks is to be suppressed, the content of TiO ₂ + ZrO _{2 is} preferably 7.5% or less, 7% or less, 6.5% or less, more preferably 6 % or less.

TiO ₂ is a component that effectively increases the refractive index without swelling the batch cost. However, if the content of TiO ₂ increases, the glass is colored and the Devitrification resistance decreases. The content of TiO ₂ is therefore preferably from 0.01% to 15%, from 0.1 to 15%, from 1% to 12%, from 2% to 11%, from 3% to 10%, from 4% to 9%, more preferably from 5% to 8%. Note that as the content of TiO ₂ increases, the production of Zr-containing devitrification pebbles is accelerated. Therefore, in the case where the generation of Zr-containing devitrifying stains is to be suppressed, the content of TiO ₂ is preferably 6% or less, 5.5% or less, 5% or less, 4.5% or less, particularly preferably 4 % Or less.

ZrO ₂ is a component that effectively increases the refractive index without causing the batch cost to swell. However, as the content of ZrO ₂ increases, the liquidus temperature decreases. Therefore, the content of ZrO _{2 is} preferably from 0% to 10%, from 0.01 to 10%, from 0.5% to 8%, from 1% to 7%, from 1.5% to 6.5%, from 2.5% to 6%, more preferably from 3% to 5.5%. Note that, in the case where the generation of Zr-containing devitrification bricks is to be suppressed, the content of ZrO _{2 is} preferably 5% or less, 4% or less, 3.5% or less, 3% or less, more preferably 2 , 5% or less.

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

The content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably from 30% to 80%. When the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ decreases, it is difficult to form a glass network structure, which leads to difficulties in glass formation. Further, the viscosity of the glass extremely lowers, and therefore, it becomes difficult to ensure a high liquidus viscosity. The content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 30% or more, 35% or more, 38% or more, 40% or more, 42% or more, 45% or more, 47% or more, 49% or more, more preferably 50% or more. On the other hand, if the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ increases, the meltability and the moldability are lowered, and the refractive index decreases. The content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is therefore preferably 80% or less, preferably 75% or less, 70% or less, 65% or less, 60% or less, 57% or less, especially preferably 55% or less. Note that the term "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 .

The mass ratio (SrO + BaO + TiO ₂ + ZrO ₂ ) / (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) is 0.1 to 3. When the mass ratio (SrO + BaO + TiO ₂ + ZrO ₂ ) / (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) decreases, it becomes difficult to increase the refractive index. The lower limit of the mass ratio (SrO + BaO + TiO ₂ + ZrO ₂ ) / (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) is therefore preferably 0.1, 0.3, 0.4, 0.5 , 0.6, 0.7, 0.8, more preferably 0.9. On the other hand, when the mass ratio (SrO + BaO + TiO ₂ + ZrO ₂ ) / (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) increases, the glass formation becomes difficult and the viscosity of the glass is greatly reduced and therefore it is difficult to ensure a high liquidus viscosity. The upper limit of the mass ratio (SrO + BaO + TiO ₂ + ZrO ₂ ) / (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) is therefore preferably 3, 2, 1.5, 1.3, 1.1 , more preferably 1. Note that the term "SrO + BaO + TiO ₂ + ZrO ₂ " refers to the total amount of SrO, BaO, TiO ₂ and ZrO ₂ .

The content of SiO ₂ is preferably from 30% to 70%. As the content of SiO ₂ decreases, it is difficult to form a glass network structure, resulting in difficult glass formation. In addition, the viscosity of the glass extremely lowers, and therefore, it is difficult to ensure a high liquidus viscosity. The content of SiO ₂ is therefore preferably 30% or more, 33% or more, 35% or more, 37% or more, 38% or more, 39% or more, particularly preferably 40% or more. On the other hand, when the content of SiO ₂ increases, the meltability, the moldability and the refractive index decrease. The content of SiO ₂ is therefore preferably 70% or less, 65% or less, 60% or less, 55% or less, 53% or less, 51% or less, less than 50%, 48% or less, 43%. or less, more preferably 41% or less.

The content of Al ₂ O ₃ is preferably 0 to 20%. As the content of Al ₂ O ₃ increases, devitrification crystals in the glass separate, the liquidus viscosity decreases, and the refractive index decreases. The content of Al ₂ O ₃ is therefore preferably 20% or less, 15% or less, 10% or less, 8% or less, particularly preferably 6% or less. Note that the glass composition loses its balance and the glass degasifies as the content of Al ₂ O ₃ decreases. The content of Al ₂ O ₃ is therefore preferably 0.1% or more, 0.5 or more, 1% or more, 3% or more, 4% or more, particularly preferably 5% or more.

The mass ratio CaO / Al ₂ O ₃ is preferably 1.15 or less, 1.1 or less, 1 or less, 0.9 or less, from 0.1 to 0.8, from 0.2 to 0.7, from 0.3 to 0.65, more preferably from 0.4 to 0.6. Thus, the devitrification resistance is improved and the glass can be easily formed into a glass plate by an overflow-down-draw method. Note that the term "CaO / Al ₂ O ₃ " refers to a value obtained by dividing the content of CaO by the content of Al ₂ O ₃ .

The content of B ₂ O ₃ is preferably 0 to 15%. As the content of B ₂ O ₃ increases, the refractive index and the Young's modulus decrease. The content of B ₂ O ₃ is therefore preferably 15% or less, 13% or less, 12% or less, 10% or less, 8% or less, particularly preferably 6% or less. Note that the liquidus temperature lowers as the content of B ₂ O ₃ decreases. The content of B ₂ O ₃ is therefore preferably 0.1% or more, 1% or more, 2% or more, 3% or more, 4% or more, particularly preferably 5% or more.

The mass ratio (B ₂ O ₃ + MgO) / CaO is preferably 1 or more, 1.3 or more, 1.5 or more, 1.6 or more, from 1.65 to 5, from 1.7 to 4, 5, from 1.8 to 4, from 1.9 to 3.5, more preferably from 2 to 3. Thus, both the devitrification resistance and the fusibility can be easily improved, and therefore the productivity of a glass plate is easily improved. Note that the expression "(B ₂ O ₃ + MgO) / CaO" refers to a value obtained by dividing the total content of B ₂ O ₃ and MgO by the content of CaO.

The mass ratio of B ₂ O ₃ / TiO ₂ is preferably from 0.1 to 50, from 0.3 to 30, from 0.5 to 20, from 0.7 to 10, from 0.8 to 5, from 0, 9 to 4, more preferably from 1 to 3. Thus, the devitrification resistance is improved and the glass can be easily formed into a glass plate by an overflow-down-draw method. Note that the term "B ₂ O ₃ / TiO ₂ " refers to a value obtained by dividing the content of B ₂ O ₃ by the content of TiO ₂ .

An alkali metal oxide is a component that lowers the viscosity of the glass, and is a component that adjusts the coefficient of thermal expansion. However, if the alkali metal oxide is added in a large amount, the viscosity of the glass excessively lowers, and therefore it becomes difficult to ensure a high liquidus viscosity. Moreover, depending on the application, it is necessary to form a passivation film on a surface of the glass, such as a SiO ₂ film. Therefore, the content of alkali metal oxide is preferably 15% or less, 10% or less, 5% or less, 2% or less, 1% or less, more preferably 0.5% or less, and desirably, the high refractive index glass is Essentially free of alkali metal oxide. Note that the contents of Li ₂ O, Na ₂ O and K ₂ O are each preferably 10% or less, 8% or less, 5% or less, 2% or less, 1% or less, more preferably 0.5% or less, and it is desirable that the high refractive index glass be substantially free of Li ₂ O, Na ₂ O and K ₂ O.

As the refining agent, one or two species selected from the group consisting of As ₂ O ₃ , Sb ₂ O ₃ , CeO ₂ , SnO ₂ , F, Cl and SO ₃ may be added in an amount of 0 to 3%. Note that, for environmental reasons, it is preferable that the high refractive index glass is substantially free of As ₂ O ₃ and F, especially As ₂ O ₃ . In particular, Sb ₂ O ₃ , SnO ₂ , SO ₃ and Cl are each preferably used as the refining agent. The content of Sb ₂ O ₃ is preferably 0% to 1%, from 0.01% to 0.5%, particularly preferably from 0.05% to 0.4%. The content of SnO ₂ is preferably from 0% to 1%, from 0.01% to 0.5%, particularly preferably from 0.05% to 0.4%. The content of SnO ₂ + SO ₃ + Cl is preferably from 0% to 1%, from 0.001% to 1%, from 0.01% to 0.5%, particularly preferably from 0.01% to 0.3%. Herein, the term "SnO ₂ + SO ₃ + Cl" refers to the total amount of SnO ₂ , SO ₃ and Cl.

PbO is a component which lowers the viscosity at high temperature, but from the environmental point of view, it is preferred that the high refractive index glass be substantially free of PbO.

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 which increases the refractive index but is also a component which 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%, more preferably 0.5% or less, and it is preferred that the high refractive index glass is substantially free of Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ . Note that 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} each 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, and it is desirable that the high refractive index glass be substantially free of Bi ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ and WO ₃ .

In addition to the above components, other components may be added. The additional amounts thereof are preferably 10%, 5% or less, more preferably 3% or less.

It is preferable that the high refractive index glass of the present invention has the following properties.

The refractive index n _d is 1.51 or more, preferably 1.55 or more, 1.57 or more, 1.58 or more, 1.60 or more, 1.62 or more, particularly preferably 1.63 or more. When the refractive index n _{d is} less than 1.55, light can not be effectively extracted because of the reflection at the interface between an ITO film and the glass. On the other hand, as the refractive index n _d increases, the glass composition loses its balance, with the result that the devitrification resistance decreases. In addition, when the refractive index n _d greatly increases, the reflection at the air-glass interface increases, and therefore, it is difficult to improve the light extraction efficiency even if the surface of the glass is subjected to a roughening treatment. Note that the refractive index n _d can be increased while the devitrification resistance is ensured when a heavy metal is added, but in this case, the batch cost increases. Therefore, the refractive index n _{d is} 2.0 or less, preferably 1.70 or less, 1.68 or less, 1.67 or less, 1.66 or less, particularly preferably 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, more preferably 3.5 g / cm ³ or less. Thus, the weight of a device can be reduced. Note that the density can be measured by a well-known Archimedes method.

The coefficient of thermal expansion at from 30 ° C to 380 ° C is preferably from 30 × 10 ^-7 / ° C to 100 × 10 ^-7 / ° C, from 40 × 10 ^-7 / ° C to 90 × 10 ^-7 / ° C, from ^{60x10 -7} / ° C to ^{85x10 -7} / ° C, from ^{65x10 -7} / ° C to ^{80x10 -7} / ° C. In recent years, in OLED devices such as an OLED lighting device or an OLED display and a dye solar cell, in some cases, from the viewpoint of improving their design elements, the glass plates have been required to be flexible. To increase the flexibility of the thickness of the glass plate must be reduced. In this case, if the coefficient of thermal expansion of the glass plate does not agree with that of the transparent conductive film, such as an ITO film or an FTO film, the glass plate is liable to warp. Thus, if the coefficient of thermal expansion at 30 to 380 ° C is regulated within the above range, such a situation as described above can be easily prevented. Note that the "coefficient of thermal expansion at 30 to 380 ° C" can be measured, for example, with a dilatometer.

The lower cooling point is preferably 500 ° C or more, 540 ° C or more, 550 ° C or more, 580 ° C or more, 590 ° C or more, 600 ° C or more, 620 ° C or more, most preferably 640 ° C or more. Thus, even if a high temperature treatment is performed during a step of manufacturing a device, the glass plate resists heat shrinkage.

The temperature at 10 ^2.0 dPa · s is preferably 1,000 ° C or more, 1,100 ° C or more, 1,130 ° C or more, 1,200 ° C or more, 1,220 ° C or more, 1,240 ° C or more, 1,250 ° C or more, more preferably 1260 ° C or more. Thus, the molding temperature is easily increased and therefore the devitrification can be easily prevented during molding.

The liquidus temperature is preferably 1,200 ° C or less, 1,150 ° C or less, 1,130 ° C or less, 1,110 ° C or less, 1,050 ° C or less, 1,030 ° C or less, more preferably 1,000 ° C or less. Further, the liquidus 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 ^4.5 dPa · S or more, 10 ^4.8 dPa · s or more, 10 ^5.0 dPa · s or more, 10 ^5.2 dPa · s or more, particularly preferably 10 ^5.3 dPa · s or more. As a result, the glass hardly peels during shaping and the glass can easily be shaped into a glass plate by an overflow-down-draw process.

The high refractive index glass of the present invention preferably has a flat plate shape and has a thickness of 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 or less, 0.3 mm or less, 0.2 mm or less, particularly preferably 0.1 mm or less. As the thickness becomes smaller, flexibility increases, and a lighting device of excellent design can be easily manufactured. If the thickness however, becomes extremely small, the glass tends to break. Therefore, the thickness is preferably 10 μm or more, more preferably 30 μm or more.

When the high refractive index glass of the present invention has a plate shape, the high refractive index glass preferably has at least one unpolished surface. The theoretical strength of glass is intrinsically very high. However, glass breaks even at much lower loads than the theoretical strength. This is because in some steps after forming the glass into a glass plate such as a polishing step, small defects are generated in the surface of the glass called Griffith cracks. Therefore, if the glass surface is not polished, the mechanical strength intrinsically exhibited by the glass is not easily deteriorated, and therefore the glass does not break easily. Further, if a glass surface is not polished, the polishing step may be omitted, and therefore the manufacturing cost of the glass plate may be reduced.

The high refractive index glass of the present invention has at least one surface (assuming that surface is an effective surface) having a surface roughness Ra of preferably 10 Å or less, 5 Å or less, 3 Å or less, more preferably 2 Å or less having. When the surface roughness Ra is more than 10 Å, the quality of an ITO film to be formed on the surface deteriorates and uniform light emission is difficult to be achieved.

The high refractive index glass of the present invention is preferably subjected to roughening treatment by HF etching, sandblasting or the like on one of its surfaces. The surface roughness Ra of the roughened surface is preferably 10 Å or more, 20 Å or more, 30 Å or more, particularly preferably 50 Å or more. When the roughened surface is disposed on the side of an OLED lighting device or the like which is brought into contact with air, the light generated in an organic light-emitting layer does not easily revert to the organic surface due to the non-reflective structure of the roughened surface. Light-emitting layer back. Consequently, the light extraction efficiency can be improved. Further, irregularities may be created in a surface by thermal operations such as re-pressing. Thus, a precise non-reflective structure can be formed in a surface. It is recommended to adjust the interval and the depth of refractive index irregularities. Further, a resin film having irregularities (having a surface roughness Ra of preferably 10 Å or more, 20 Å or more, 30 Å or more, particularly preferably 50 Å or more) may be applied on a surface of the glass.

When the roughening treatment is performed by atmospheric plasma processing, while forming a uniform non-reflective structure on one surface, the surface state of the other surface can be maintained. It is further preferred to use an F-containing gas (such as SF ₆ or CF ₄ ) as a source of atmospheric plasma processing.

Thus, a plasma containing a HF-based gas is generated, and therefore the efficiency of the roughening treatment is improved.

Note that when forming a non-reflective structure on a surface with a forming roll in the molding, the non-reflective structure can provide the same effect as that of the roughening treatment even if the roughening treatment is not performed. Further, a light scattering film having irregularities may be applied to a surface.

It is preferable that the high refractive index glass of the present invention has a light scattering function by phase separation. Thus, light in a glass plate can be easily extracted in air without forming a surface roughened on a surface or applying a light diffusing film to a surface. During the production process of the glass plate, the phase separation can be initiated in each case during melting, during shaping or during tempering. The phase separation can also be caused by separately subjecting a glass which has not undergone phase separation to a heat treatment.

Hereinafter, a method for producing the high-refractive-index glass of the present invention will be explained. First, by mixing the glass raw materials, a glass batch is prepared so that a desired glass composition is achieved. Next, the glass batch is melted, refined and then formed into a desired shape. Then the result is worked into the desired shape.

The high refractive index glass of the present invention is preferably formed by an overflow down draw method. This can cost a large number of unpolished glass plates are produced, each having a good surface quality. Furthermore, the glass plate can be easily enlarged and thinned.

As a method for molding the glass into a glass plate, in addition to the overflow-down-draw method, for example, a float method, a slot-down draw method, a re-draw method or a roll-out method can be used.

Second invention

A high refractive index glass according to the second embodiment comprises as the glass composition, in mass percentage, 30% to 80% of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ , 0.1% to 20% of B ₂ O ₃ + ZnO and 3% to 20% of TiO ₂ + ZrO ₂ . Hereinafter, the reasons why the content ranges of the components are limited as described above will be described, but the detailed description of the cases common to the high refractive index glass according to the first invention will be omitted. Note that in the following description of the content ranges, the term "%" refers to "mass%" unless otherwise specified.

The content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is from 30% to 80% and the preferable content range is the same as that of the first invention.

The preferable range of the content of each of the components SiO ₂ , Al ₂ O ₃ , and B ₂ O ₃ is the same as that of the first invention.

In order to improve both the refractive index and the devitrification resistance, the mass ratio SiO ₂ / (Al ₂ O ₃ + B ₂ O ₃ ) is preferably from 2.5 to 4.6, from 2.8 to 4.5, from 3 to 4.4, from 3.2 to 4.3, from 3.3 to 4.2, from 3.4 to 4.1, more preferably from 3.5 to 4.

From the viewpoint of ensuring a high liquidus viscosity, the content of B ₂ O ₃ + ZnO is from 0.1% to 20%, preferably from 0.5% to 18%, from 1% to 15%, from 2% to 12% , from 3% to 10%, from 3.5% to 9%, more preferably from 4% to 8%.

The preferable range of the content of ZnO is the same as that of the first invention. In order to improve both the refractive index and the devitrification resistance, the mass ratio ZnO / B ₂ O _{3 is} preferably from 0.1 to 1.2, from 0.2 to 1.2, from 0.3 to 1.1, from 0 , 4 to 1, from 0.4 to 0.9, more preferably from 0.5 to 0.8.

The preferred range of the content of TiO ₂ + ZrO ₂ is the same as that of the first invention.

The preferable content range of each of the components TiO ₂ and ZrO ₂ is the same as that of the first invention.

In order to improve both the refractive index and the devitrification resistance, the mass ratio B ₂ O ₃ / TiO _{2 is} preferably from 0.01 to 10, from 0.1 to 5, from 0.2 to 4, from 0.3 to 3, from 0.4 to 2, more preferably from 0.5 to 1.5.

In addition to the above-mentioned components, for example, the following components can be added.

The content of MgO + CaO + SrO + BaO + ZnO can be adjusted to from 25% to 60% in the same manner as in the first invention. The preferable content of MgO + CaO + SrO + BaO + ZnO is the same as that of the first invention.

As the mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO decreases, the density and coefficient of thermal expansion increase and the glass composition loses its balance and the devitrification resistance decreases as its content decreases. Therefore, the mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO is preferably 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, particularly preferably 7 or more. On the other hand, when the mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO increases, the refractive index, the meltability and the Young's are lowered Module. Therefore, the mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO is preferably 10 or less, 9.5 or less, 9 or less, 8.5 or less, 8 or less, particularly preferably 7.5 or less.

The preferred range of the content of MgO + CaO is the same as that of the first invention.

The preferable range of the content of MgO is the same as that of the first invention.

The content of CaO is preferably 12% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3.5% or less, 3% or less, more preferably 2.5% or fewer. Note that the lower limit of the content of CaO is the same as that of the first invention.

The preferable range of the content of SrO is the same as that of the first invention. The preferable range of the content of BaO is the same as that of the first invention. The preferable range of the mass ratio (SrO + BaO + TiO ₂ + ZrO ₂ ) / (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) is the same as that of the first invention.

Li ₂ O + Na ₂ O + K ₂ O is a component that lowers the viscosity of the glass, and is a component that adjusts the coefficient of thermal expansion of the glass. However, when Li ₂ O + Na ₂ O + K ₂ O is added in a large amount, the viscosity of the glass greatly lowers, and it is difficult to ensure a high liquidus viscosity. Moreover, depending on the application, it is necessary to form a passivation film on a surface of the glass, such as a SiO ₂ film. Therefore, the content of alkali metal oxide is preferably 15% or less, 10% or less, 5% or less, 2% or less, 1% or less, more preferably 0.5% or less, and desirably, the high refractive index glass is Essentially free of alkali metal oxide. Note that the contents of Li ₂ O, Na ₂ O and K ₂ O are each preferably 10% or less, 8% or less, 5% or less, 2% or less, 1% or less, more preferably 0.5% or less, and it is desirable that the high refractive index glass be substantially free of Li ₂ O, Na ₂ O and K ₂ O.

As the refining agent, the same as those of the first invention may be added. Furthermore, the content of refining agent and the like are the same as those of the first invention.

It is preferred that the high refractive index glass as in the first invention be substantially free of PbO.

The preferred range of 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 the same as that of the first invention. Further, the preferable content range of each 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} also the same as that of the first invention.

In addition to the above-mentioned components, other components may be added. The additional amounts thereof are preferably 10%, 5% or less, more preferably 3% or less.

It is preferred that the high refractive index glass of the present invention also exhibit the various properties described in the first invention (refractive index n _d , density, coefficient of thermal expansion, lower cooling point, temperature at 10 ^2.0 dPa · s, liquidus temperature, Liquidus viscosity, shape, thickness and surface roughness). Further, the working methods to impart the various characteristics and the like are the same as those of the first invention.

As a method for producing the high-refractive-index glass of the present invention, the manufacturing method described in the first invention is equally applicable.

Third invention

A high refractive index glass according to the third invention comprises as the glass composition 3 mass% to 20 mass% of TiO ₂ + ZrO ₂ , and has a mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO of 2 to 10. Hereinafter, the reasons why the content ranges of the components are limited as described above will be described, but the detailed description of the cases common to the high refractive index glass according to the first and second invention will be omitted. Note that in the following description of the content ranges, the term "%" refers to "mass%" unless otherwise specified.

The content of TiO ₂ + ZrO ₂ is from 3% to 20%, and the preferable range of the content is the same as that of the first invention.

The preferable content range of each of the components TiO ₂ and ZrO ₂ is the same as that of the first invention.

The mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO is from 2 to 10, and the preferable range of the mass ratio is the same as that of the second invention.

The preferable range of the content of MgO + CaO + SrO + BaO + ZnO is the same as that of the first invention.

The preferable range of each of the components MgO, SrO, BaO and ZnO excluding CaO is also the same as that of the first invention.

As the content of CaO decreases, the refractive index, meltability and Young's modulus decrease. The content of CaO is therefore preferably more than 5%, 6% or more, 7% or more, particularly preferably 8% or more. On the other hand, when the content of CaO increases, the density and coefficient of thermal expansion increase. If the content increases greatly, the glass composition loses its balance and the devitrification resistance decreases. Therefore, the content of CaO is preferably 15% or less, 13% or less, 12% or less, 11% or less, 10% or less, particularly preferably 9% or less.

The preferable range of the content of SiO ₂ is the same as that of the first invention.

The preferable range of the content of Al ₂ O ₃ is the same as that of the first invention.

The preferred range of the content of B ₂ O ₃ is the same as that of the first invention.

The preferred range of the mass ratio B ₂ O ₃ / TiO ₂ is the same as that of the first invention.

The mass ratio (ZnO + B ₂ O ₃ ) / TiO ₂ is preferably from 0.7 to 10, from more than 0.9 to 7, from 1 to 5, from 1.5 to 4.5, particularly preferably from 1, 8 to 3.5. Thus, the devitrification resistance is improved and the glass can be easily formed into a glass plate by an overflow-down-draw method. Note that the term "ZnO + B ₂ O ₃ " refers to the total amount of ZnO and B ₂ O ₃ . The term "(ZnO + B ₂ O ₃ ) / TiO ₂ " refers to a value obtained by dividing the total amount of ZnO and B ₂ O ₃ by the content of TiO ₂ .

The preferable range of the content of alkali metal oxide is the same as that of the first invention.

As the refining agent, the same as those of the first invention may be added. Furthermore, the content of refining agent and the like are the same as those of the first invention.

It is preferred that the high refractive index glass as in the first invention be substantially free of PbO.

The preferred range of 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 the same as that of the first invention. Further, the preferable content range of each 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} also the same as that of the first invention.

TiO ₂ - (Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ ) is preferably 0.1 or more, 0.5 or more, 1 or more, 1.5 or more, from 2 to 8, from 2.5 to 7, more preferably from 3 to 6. Thus, the refractive index is improved while the batch cost is kept low. Note that the term "TiO ₂ - (Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ )" refers to an amount obtained by subtracting 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 obtained} from the content of TiO ₂ .

In addition to the above-mentioned components, other components may be added. The additional amounts thereof are preferably 10%, 5% or less, more preferably 3% or less.

It is preferred that the high refractive index glass of the present invention also exhibit the various properties described in the first invention (refractive index n _d , density, coefficient of thermal expansion, lower cooling point, temperature at 10 ^2.0 dPa · s, liquidus temperature, Liquidus viscosity, shape, thickness and surface roughness). Further, the working methods to impart the various characteristics and the like are the same as those of the first invention.

As a method for producing the high-refractive-index glass of the present invention, the manufacturing method described in the first invention is equally applicable.

Fourth invention

A high refractive index glass according to the fourth invention comprises as the glass composition, in mass percentage, 26% to 70% of SiO ₂ , 4.5% to 35% of B ₂ O ₃ , 10% to 48% of MgO + CaO + SrO + BaO + ZnO, 10% to 31% of BaO and 0% to 0.29% of Li ₂ O + Na ₂ O + K ₂ O. The following describes the reasons why the content ranges of the components are limited as described above. however, the detailed description of the cases common to the high refractive index glass according to the first, second and third inventions will be omitted. Note that in the following description of the content ranges, the term "%" refers to "mass%" unless otherwise specified.

The content of SiO ₂ is from 26% to 70%. The content of SiO ₂ is preferably 26% or more, 30% or more, 32% or more, 34% or more, particularly preferably 36% or more. On the other hand, if the content of SiO ₂ increases, the refractive index, the meltability and the moldability are lowered. 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 preferably 43% or less.

The content of B ₂ O ₃ is from 4.5% to 35%. An upper limit for the content of B ₂ O ₃ is preferably 35%, 30%, 25%, 20%, 18%, particularly preferably 16%. A lower limit for the content of B ₂ O ₃ is preferably 4.5%, 6%, 8%, 9%, particularly preferably 10%.

The mass ratio SiO ₂ / B ₂ O ₃ is preferably from 1.2 to 20. When the mass ratio SiO ₂ / B ₂ O ₃ decreases, the viscosity decreases and the liquidus viscosity decreases. A lower limit for the mass ratio SiO ₂ / B ₂ O ₃ is therefore preferably 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, particularly preferably 2.5. On the other hand, if the mass ratio SiO ₂ / B ₂ O ₃ increases, the devitrification resistance lowers and the liquidus viscosity decreases. An upper limit for the mass ratio SiO ₂ / B ₂ O ₃ is therefore preferably 20, 15, 10, 5, 4.0, 3.8, 3.6, 3.4, 3.2, particularly preferably 3.0.

The content of MgO + CaO + SrO + BaO + ZnO is preferably from 10% to 48%, from 20% to 47%, from 25% to 46%, from 30% to 45%, from 32% to 42%, especially preferably from 34% to 40%.

When the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is controlled to fall within a predetermined range, the high refractive index, devitrification resistance, fusibility, low density and low coefficient of thermal expansion can simultaneously high level can be achieved. A lower limit for the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is therefore preferably 1, 1.5, 1.8, more preferably 2. An upper limit for the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O ₃ is furthermore preferably 6, 5, 4.5, particularly preferably 4. It should be noted that there is a risk that the density and the coefficient of thermal expansion increase disproportionately when the mass ratio ( MgO + CaO + SrO + BaO + ZnO) / B ₂ O _{3 is} extremely large. When the mass ratio (MgO + CaO + SrO + BaO + ZnO) / B ₂ O _{3 is} extremely small, the refractive index, the devitrification resistance and the meltability decrease.

The preferable range of the content of MgO is the same as that of the first invention.

The preferable range of the content of CaO is the same as that of the second invention.

When the mass ratio CaO / B ₂ O ₃ is controlled to fall within a predetermined range, the devitrification resistance is easily improved. A lower limit for the mass ratio CaO / B ₂ O ₃ is therefore preferably 1, 2, 2.5, 3, particularly preferably 3.5. An upper limit for the mass ratio CaO / B ₂ O ₃ is furthermore preferably 10, 8, 7, 6, particularly preferably 5.5.

The preferable range of the content of SrO is the same as that of the first invention.

An upper limit of the content of BaO is preferably 31%, 28%, 26%, 24%, 22%, particularly preferably 20%. A lower limit of the content of BaO is preferably 10%, 11%, 12%, 13%, 14%, 15%, particularly preferably 16%. When the mass ratio BaO / B ₂ O ₃ is controlled to fall within a predetermined range, both the high refractive index and the high liquidus viscosity can be achieved at a high level. A lower limit for the mass ratio BaO / B ₂ O ₃ is therefore preferably 0.5, 0.6, 0.7, 0.8, 0.9, particularly preferably 1. An upper limit for the mass ratio BaO / B ₂ O. ₃ is furthermore preferably 5, 4.5, 4, 3.5, 3, particularly preferably 2.5. Note that the liquidus viscosity decreases when the mass ratio BaO / B ₂ O _{3 is} extremely large. If the mass ratio BaO / B ₂ O _{3 is} extremely small, the refractive index decreases.

An upper limit of the content of ZnO is preferably 15%, 12%, 10%, 8%, 6%, particularly preferably 4%. The preferable range of a lower limit of the content of ZnO is the same as that of the first invention.

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 preferably 0.05% or less, and it is desirable in that the high refractive index glass is substantially free of Li ₂ O + Na ₂ O + K ₂ O. Note that the content of each of the components Li ₂ O, Na ₂ O and K ₂ O is 0.29% or less, 0.20% or less, 0.10% or less, more preferably 0.05% or less, and it is desirable that the high refractive index glass be substantially free of Li ₂ O, Na ₂ O, and K ₂ O.

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

The content of Al ₂ O ₃ can be adjusted to 0% to 20% as in the first invention. The preferred content of Al ₂ O ₃ is the same as that of the first invention.

The content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ can be adjusted to 30.5% to 80%. A lower limit for the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 30.5%, 35%, 40%, 42%, 46%, 50%, particularly preferably 54%. An upper limit of the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 80%, 75%, 70%, 65%, 62%, 61%, particularly preferably 60%.

It is preferable that the high refractive index glass as in the first invention is substantially free of PbO.

The preferred range of 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 the same as that of the first invention. In addition, the preferable range of the content of each of the components Bi ₂ O ₃ , La ₂ O _3, Gd ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and WO ₃ is also the same as that of the first invention.

The preferable range of the content of TiO ₂ is the same as that of the first invention.

The preferred range of the content of ZrO ₂ is the same as that of the first invention.

As the content of P ₂ O ₅ increases, the glass composition loses its balance and the devitrification resistance decreases. The content of P ₂ O ₅ is therefore preferably 15% or less, 10% or less, 6% or less, particularly preferably 4% or less.

As the refining agent, the same as those of the first invention may be added. Furthermore, the content of refining agent and the like are the same as those of the first invention.

In addition to the above-mentioned components, other components may be added. The additional amounts thereof are preferably 10%, 5% or less, more preferably 3% or less.

It is preferred that the high refractive index glass of the present invention also exhibit the various properties described in the first invention (refractive index n _d , density, coefficient of thermal expansion, lower cooling point, temperature at 10 ^2.0 dPa · s, liquidus temperature, Liquidus viscosity, shape, thickness and surface roughness). Further, the working methods to impart the various characteristics and the like are the same as those of the first invention.

Examples

example 1

Hereinafter, examples of the first invention will be described. Note that the examples given below are for illustrative purposes only. The first invention is by no means limited to the following examples.

Tabelle 2

The examples (Sample Nos. 1 to 21) of the first invention are shown in Tables 1 and 2. Table 1

Table 2

First, the glass materials were mixed so that each of the glass compositions described in Tables 1 and 2 was achieved. Thereafter, the resulting glass batch was placed in a glass melting furnace and melted at 1,400 to 1,500 ° C for 4 hours. Next, the resulting molten glass was poured on a carbon plate to form it into a flat plate shape, followed by a predetermined annealing. Finally, the resulting glass plate was examined for its various properties.

The density ρ is a value obtained by measurement using the well-known Archimedes method.

The coefficient α of the thermal expansion is a value obtained by measuring a mean coefficient of thermal expansion at 30 to 380 ° C with a dilatometer. As a measuring sample, a cylindrical sample (having end surfaces which were subjected to rounding) having a size of 5 mm in diameter by 20 mm in length was used.

The lower cooling point Ps is a value obtained by a measurement based on the method described in ASTM C336-71. Note that the heat resistance becomes higher as the lower cooling point becomes higher.

The upper cooling point Ta and the softening point Ts are values obtained by a measurement based on the method described in ASTM C338-93.

The temperatures at the 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 obtained by measurement using a platinum ball pull-up device. Procedure were obtained. Note that the lower the temperatures become, the better the meltability.

The liquidus temperature TL is a value obtained by measuring a temperature at which crystals of the glass are deposited when glass powder passing through a standard 30-mesh (500 μm) sieve is placed on a 50-mesh sieve (FIG. 300 μm), placed in a platinum boat and kept in a gradient oven for 24 hours. The liquidus viscosity logηTL is further a value obtained by measuring the viscosity of the glass at its liquidus temperature by a platinum sphere pull-up method. It should be noted that the higher the liquidus viscosity and lower the liquidus temperature, the better the devitrification resistance and moldability become.

The refractive index n _d is a value obtained by measurement with a refractometer KPR-2000 manufactured by Shimadzu Corporation, which is a measurement at the d-line (wavelength: 587.6 nm) of a hydrogen lamp. Note that, for measurement, after samples each having a 25 mm by 25 mm by 3 mm rectangular parallelogram shape were prepared, the samples were annealed at a cooling rate of 0.1 ° C / min in a temperature range from (upper cooling point Ta + 30 ° C) to (lower cooling point - 50 ° C), and then an immersion liquid having a refractive index matching that of the samples is inserted between glasses.

As can be seen from Tables 1 and 2, Samples 1 to 21 each had a high refractive index n _d and, given that they did not contain expensive heavy metals, had a satisfactory devitrification resistance.

Further, glass materials were mixed for each of the materials described in Samples Nos. 1 to 21, and then the resultant glass batch was placed in a continuous furnace and melted at a temperature of 1,300 to 1,500 ° C. Subsequently, the molten glass was shaped by an overflow-down draw method into a glass plate having a thickness of 0.7 mm. The resulting glass plate was measured for its average surface roughness Ra. As a result, the average surface roughness value was 2 Å in each case. Note that the term "surface roughness Ra" refers to a value obtained by measurement using a method according to JIS B0601: 2001.

Example 2

Hereinafter, examples of the second invention will be described. Note that the examples given below are for illustrative purposes only. The first invention is by no means limited to the following examples.

Tabelle 4

Tabelle 5

Tabelle 6

Tabelle 7

Tabelle 8

Tabelle 9

Tabelle 10

Tabelle 11

Tabelle 12

Tabelle 13

The examples (Sample Nos. 22 to 130) of the second invention are shown in Tables 3 to 13. Table 3

Table 4

Table 5

Table 6

Table 7

Table 8

Table 9

Table 10

Table 11

Table 12

Table 13

First, the glass materials were mixed so that each of the glass compositions described in Tables 3 to 13 was achieved. Thereafter, the resulting glass batch was placed in a glass melting furnace and melted at 1,400 to 1,500 ° C for 4 hours. Next, the resulting molten glass was poured on a carbon plate to form it into a flat plate shape, followed by a predetermined annealing. Finally, the resulting glass plate was examined for its various properties.

Note that the methods for measuring the density ρ, the coefficient α of the thermal expansion, the lower cooling point Ps, the upper cooling point Ta, the softening point Ts, the temperatures at the high temperature, the liquidus temperature TL, and the refractive index n _{d are the} same as those described in Example 1 according to the first invention.

As can be seen from Tables 3 to 13, Samples 22 to 130 each had a high refractive index n _d and, in view of not containing expensive heavy metals, had a satisfactory devitrification resistance.

Further, in the sample Nos. 25, 28, 30, 31, 33, 35, 39 to 41, 44, 45, 47, 56, 57, 61, 63 to 65, 70, 71, 73, 78, 82 to 85, 87, 88, 91 to 94, 99, 102 to 106, 116 and 119, respectively, mixed glass materials, and then the resulting glass batch was placed in a continuous furnace and melted at a temperature of 1300 to 1500 ° C. Subsequently, the molten glass formed by an overflow-down-draw process in a glass plate, which had a thickness of 0.7 mm. The resulting glass plate was measured for its average surface roughness Ra. As a result, the average surface roughness value was 2 Å in each case. Note that the surface roughness measurement method Ra is the same as the method described in Example 1 according to the first invention.

Example 3

In the following, examples of the third invention will be described. Note that the examples given below are for illustrative purposes only. The first invention is by no means limited to the following examples.

The examples (Sample Nos. 131 to 141) of the third invention are shown in Table 14. Table 14

First, the glass materials were mixed so as to achieve each of the glass composition described in Table 14. Thereafter, the resulting glass batch was placed in a glass melting furnace and melted at 1,400 to 1,500 ° C for 4 hours. Next, the resulting molten glass was poured on a carbon plate to form it into a flat plate shape, followed by a predetermined annealing. Finally, the resulting glass plate was examined for its various properties.

Note that the methods for measuring the density ρ, the coefficient α of the thermal expansion, the lower cooling point Ps, the upper cooling point Ta, the softening point Ts, the temperatures at the high temperature, the liquidus temperature TL, and the refractive index n _{d are the} same as those described in Example 1 according to the first invention.

As can be seen from Table 14, Samples 131 to 141 each had a high refractive index n _d and, given that they did not contain expensive heavy metals, had a satisfactory devitrification resistance.

Further, glass materials were respectively mixed for the materials described in Samples Nos. 131 to 138, 140 and 141, and then the resulting glass batch was placed in a continuous furnace and melted at a temperature of 1300 to 1500 ° C. Subsequently, the molten glass was shaped by an overflow-down draw method into a glass plate having a thickness of 0.7 mm. The resulting glass plate was measured for its average surface roughness Ra. As a result, the average surface roughness value was 2 Å in each case. Note that the surface roughness measurement method Ra is the same as the method described in Example 1 according to the first invention.

Example 4

Hereinafter, examples of the fourth invention will be described. Note that the examples given below are for illustrative purposes only. The first invention is by no means limited to the following examples.

n.b. = nicht bestimmt Tabelle 16

n.b. = nicht bestimmtThe examples (Sample Nos. 142 to 166) of the fourth invention are shown in Tables 15 and 16. Table 15

nb = not determined Table 16

nb = not determined

First, the glass materials were mixed so that each of the glass compositions described in Tables 15 and 16 was achieved. Thereafter, the resulting glass batch was placed in a glass melting furnace and melted at 1,300 to 1,400 ° C for 7 hours. Next, the resulting molten glass was poured on a carbon plate to form it into a flat plate shape, followed by a predetermined annealing. Finally, the resulting glass plate was examined for its various properties.

Note that the methods for measuring the density ρ, the coefficient α of the thermal expansion, the lower cooling point Ps, the upper cooling point Ta, the softening point Ts, the temperatures at the high temperature, the liquidus temperature TL, and the refractive index n _{d are the} same as those described in Example 1 according to the first invention.

As can be seen from Tables 15 and 16, Samples 142 to 166 each had a high refractive index n _d and, given that they did not contain expensive heavy metals, had a satisfactory devitrification resistance.

Claims (17)

High refractive index glass comprising, by mass, 25% to 60% of MgO + CaO + SrO + BaO + ZnO, 0% to 5% of CaO, and 3% to 20% of TiO ₂ + ZrO ₂ , as a glass composition, and one Having refractive index n _d of 1.51 to 2.0. High refractive index glass comprising, as a glass composition, in mass percent, 30% to 80% of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ , 0.1% to 20% of B ₂ O ₃ + ZnO, and 3% to 20% of TiO ₂ + ZrO ₂ , and having a refractive index n _d of 1.51 to 2.0. High refractive index glass comprising as a glass composition 3 mass% to 20 mass% TiO ₂ + ZrO ₂ , a mass ratio (MgO + CaO + SrO + BaO + ZnO) / CaO of 2 to 10 and a refractive index n _d of 1.51 to 2.0 has. The high refractive index glass according to claim 3, wherein the high refractive index glass comprises more than 5.0 mass% of CaO. The high refractive index glass according to any one of claims 1 to 4, wherein the high refractive index glass comprises 0.1 mass% to 15 mass% of B ₂ O ₃ . High refractive index glass comprising, by mass, as glass composition, 26% to 70% of SiO ₂ , 4.5% to 35% of B ₂ O ₃ , 10% to 48% of MgO + CaO + SrO + BaO + ZnO, 10% to 31% of BaO and 0% to 0.29% of Li ₂ O + Na ₂ O + K ₂ O, and having a refractive index n _d of 1.51 to 2.0. The high refractive index glass according to any one of claims 1 to 6, wherein the high refractive index glass comprises 0.01 mass% to 10 mass% of ZrO ₂ . The high refractive index glass according to any one of claims 1 to 7, wherein the high refractive index glass comprises 0.01 mass% to 15 mass% of TiO ₂ . The high refractive index glass according to any one of claims 1 to 8, wherein the high refractive index glass is substantially free of PbO and has a content of Bi ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO _{3 has} 9 mass% or less. The high refractive index glass according to any one of claims 1 to 9, wherein the high refractive index glass comprises 0.1 mass% to 15 mass% of ZnO. The high refractive index glass according to any one of claims 1 to 10, wherein the high refractive index glass is substantially free of an alkali metal oxide. The high refractive index glass according to any one of claims 1 to 11, wherein the high refractive index glass has a liquidus viscosity of 10 ^3.0 dPa · s or more. The high refractive index glass according to any one of claims 1 to 12, wherein the high refractive index glass has a plate shape and at least one surface of the high refractive index glass has a surface roughness Ra of 10 Å or less. The high refractive index glass according to any one of claims 1 to 13, wherein the high refractive index glass is formed by an overflow down draw method. A lighting device containing the high refractive index glass according to any one of claims 1 to 14. An OLED lighting device comprising the high refractive index glass according to any one of claims 1 to 14. OLED display containing the high refractive index glass according to any one of claims 1 to 14.