JP6016064B2 - High refractive index glass - Google Patents

Description

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

  In recent years, displays using organic EL light-emitting elements and illumination (hereinafter referred to as organic EL display, organic EL illumination) have attracted more and more attention. These organic EL devices have a structure in which an organic light emitting element is sandwiched between substrates (glass plates) on which a transparent conductive film (for example, ITO, FTO, etc.) 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 the transparent conductive film, and is emitted to the outside while being repeatedly reflected in the glass plate.

  By the way, the refractive index nd of the organic light emitting device is 1.8 to 1.9, and the refractive index nd of the transparent conductive film is 1.9 to 2.0. On the other hand, the refractive index nd of the glass plate is usually about 1.5. For this reason, the conventional organic EL device has a high reflectance due to the difference in the refractive index at the interface between the glass plate and the transparent conductive film. Therefore, there is a problem that light generated from the organic light emitting element cannot be efficiently extracted to the outside. It was.

  When high refractive index glass is used as the glass plate, the difference in refractive index at the glass plate-transparent conductive film interface can be reduced.

  As high refractive index glass, optical glass used in an optical lens or the like is known. For optical lenses and the like, optical glass is used that is heat-treated again into droplet glass that has been formed into a spherical shape by a droplet molding method or the like, and press-molded into a predetermined shape. Although this optical glass has a high refractive index nd, it has a low liquidus viscosity, so if it is not molded by a droplet molding method or the like with a high cooling rate, the glass will be devitrified during molding. Therefore, in order to solve the above problem, it is necessary to improve the devitrification resistance of the high refractive index glass.

  By the way, with a thin and large organic EL display or the like, a glass plate having a small plate thickness and a large area is required. In order to obtain such a glass plate, it is necessary to form by a float method or a down draw method (overflow down draw method, slot down draw method). However, since the conventional high refractive index glass has a low liquidus viscosity, it cannot be formed by the float method or the downdraw method, and it has been difficult to reduce the thickness and size. Even in organic EL lighting, there is a demand for an increase in size and thickness.

On the other hand, when an oxide, particularly La ₂ O ₃ , Nb ₂ O ₅ , Gd ₂ O ₃ is added to the glass composition, the refractive index nd of the glass plate can be increased while suppressing a decrease in the liquid phase viscosity to some extent. . However, such a rare metal oxide has a problem that the raw material cost is high. When a large amount of rare metal oxide is added to the glass composition, the devitrification resistance is lowered, and it becomes difficult to form the glass plate, and the acid resistance is lowered.

  Furthermore, an etching process using an acid exists in the manufacturing process of an organic EL display or the like. If the acid resistance of the glass plate is low, the glass plate is eroded and becomes cloudy in this etching process. When the glass plate becomes cloudy, the transmittance of the glass plate is lowered, and it becomes difficult to increase the definition of the display.

Therefore, the present invention is consistent with the refractive index nd of the organic light emitting device and the transparent conductive film despite the low content of rare metal oxides (particularly La ₂ O ₃ , Nb ₂ O ₅ , Gd ₂ O ₃ ). Moreover, the technical problem is to create a high refractive index glass having good devitrification resistance and acid resistance.

As a result of intensive studies, the present inventors have found that the above technical problem can be solved by regulating the glass composition range to a predetermined range, and propose the present invention. That is, the high refractive index glass of the present invention is, as a glass composition, in mass%, SiO ₂ 35 to 60%, B ₂ O ₃ 1 to 15%, Al ₂ O ₃ 0 to 15%, Li ₂ O 0 to 1. % , Na ₂ O 0 to 1 %, K ₂ O 0 to 1 %, Li ₂ O + Na ₂ O + K ₂ O 0 to 1 %, CaO 0 to 11%, SrO 2 to 25%, BaO 0.1 to 3.5 _{%, MgO + CaO + SrO +} BaO + ZnO 20~ 50%, TiO 2 0.0001~20%, ZrO 2 0.0001 ~20%, La 2 O 3 0~2.5%, the _{2 O 3 + Nb 2 O 5} 0~ 8% La And the refractive index nd is 1.55 to 2.3. Here, “MgO + CaO + SrO + BaO + ZnO” refers to the total amount of MgO, CaO, SrO, BaO, and ZnO. “La ₂ O ₃ + Nb ₂ O ₅ ” refers to the total amount of La ₂ O ₃ and Nb ₂ O ₅ . The “refractive index nd” can be measured with a refractive index measuring device. For example, a cuboid sample of 25 mm × 25 mm × about 3 mm is prepared, and then from (annealing point Ta + 30 ° C.) to (strain point Ps−50 ° C.). By annealing the temperature range at a cooling rate of 0.1 ° C./min and then infiltrating an immersion liquid having a matching refractive index nd between the glasses, using a refractive index measuring device KPR-200 manufactured by Kalnew. It can be measured. “Slow cooling point Ta” refers to a value measured by the method described in ASTM C338-93. “Strain point Ps” refers to a value measured by the method described in ASTM C336-71.

High refractive index glass of the present _{invention, SiO 2 35 ~60%, B} 2 O 3 1 ~15%, Al 2 O 3 0~15%, MgO + CaO + SrO + BaO + ZnO 20~ 50%, TiO 2 0.0001~20%, ZrO ₂ Contains 0.0001-20 %. If it does in this way, devitrification resistance can be improved, raising refractive index nd.

High refractive index glass of the present _{invention, La 2 O 3 + Nb 2} O 5 0~ containing 8%. If it does in this way, while being able to reduce raw material cost, it becomes easy to improve devitrification resistance and acid resistance.

The high refractive index glass of the present invention contains Li ₂ O 0 to 1% , Na ₂ O 0 to 1 %, K ₂ O 0 to 1 %. If it does in this way, acid resistance will improve and it will become difficult for a glass to become cloudy by the elution of an alkaline component in the etching process by an acid.

  The high refractive index glass of the present invention has a refractive index nd of 1.55 to 2.3. If it does in this way, it will become easy to match | combine with the refractive index nd of an organic light emitting element or a transparent conductive film, and the light generated from the organic light emitting element can be efficiently taken out outside.

In here, _{"Li 2 O + Na 2 O +} K 2 O " _means, Li 2 O, refers to the total amount of _Na 2 O, and _{K 2} O.

  The high refractive index glass of the present invention is preferably plate-shaped. If it does in this way, it will become easy to apply to the substrate of various devices, such as an organic EL display, organic EL lighting, and an organic thin film solar cell. Here, “plate shape” is not limitedly interpreted, and includes a film shape with a small plate thickness, such as glass in a film shape installed along a cylinder, and an uneven shape is formed on one surface. Including things.

The high refractive index glass of the present invention preferably has a liquidus viscosity of 10 ^3.0 dPa · s or more. Organic EL lighting or the like has a problem that the current density at the time of current application changes due to a slight difference in the surface smoothness of the glass plate, causing unevenness in illuminance. Further, when the glass surface is polished in order to improve the surface smoothness of the glass plate, there arises a problem that the processing cost increases. Therefore, when the liquidus viscosity is in the above range, it becomes easy to form a glass plate by an overflow down draw method or the like, and as a result, it becomes easy to produce a glass plate with good surface smoothness even if not polished. 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 on 50 mesh (300 μm) into a platinum boat and holding it in a temperature gradient furnace for 24 hours Refers to the measured value. The “overflow down draw method” is a method in which molten glass overflows from both sides of a heat-resistant bowl-shaped structure, and the overflowed molten glass joins at the lower end of the bowl-shaped structure and is stretched downward to form a glass plate. This is a molding method.

  The high refractive index glass of the present invention is preferably formed by a float method or a downdraw method. Here, the “down draw method” includes an overflow down draw method, a slot down draw method, and the like.

  The high refractive index glass of the present invention preferably has an unpolished surface on at least one surface, and the surface roughness Ra of the surface is preferably 10 mm or less. Here, “surface roughness Ra” refers to a value measured by a method based on JIS B0601: 2001.

High refractive index glass of the present invention has a glass composition, in _{mass%, SiO 2 35 ~60%,} B 2 O 3 1~15%, Al 2 O 3 0~15%, Li 2 O 0~ 1%, Na ₂ O 0 to 1 %, K ₂ O 0 to 1 %, Li ₂ O + Na ₂ O + K ₂ O 0 to 1 %, CaO 0 to 11%, SrO 2 to 25%, BaO 0.1 to 3.5%, _{MgO + CaO + SrO + BaO +} ZnO 20~ 50%, TiO 2 0.0001~20%, ZrO 2 0.0001 ~20%, La 2 O 3 0~2.5%, containing _{2 O 3 + Nb 2 O 5} 0~ 8% La . The reason for limiting the content range of each component as described above will be described below. In addition, in description of the containing range of each component,% represents the mass% unless there is particular notice.

The content of SiO ₂ is 35 60%. When the content of SiO ₂ is increased, the meltability and moldability are liable to be lowered, and the refractive index nd is liable to be lowered. Therefore, the upper limit of the content of SiO ₂ is 60% or less, preferably 50% or less, 48% or less, 45% or less, and particularly 43% or less. On the other hand, when the content of SiO ₂ decreases, it becomes difficult to form a glass network structure, and vitrification becomes difficult. In addition to the fact that the viscosity of the glass is excessively lowered and it is difficult to ensure a high liquid phase viscosity, the acid resistance is likely to be lowered. Therefore, the lower limit of the content of SiO ₂ is 35% or more, preferably 3 8% or more, particularly preferably 40% or more.

The content of B ₂ O ₃ is 1 to 15%. When the content of B ₂ O ₃ increases, the Young's modulus tends to decrease, and the strain point tends to decrease. Furthermore, the component balance of the glass composition is impaired, and in addition to the resistance to devitrification being easily lowered, the acid resistance is easily lowered. Therefore, the upper limit of the content of B ₂ O ₃ is 15% or less, preferably 10% or less, 8% or less, and particularly 6% or less. On the other hand, when the content of B ₂ O ₃ decreases, the glass liquid phase viscosity tends to decrease. Therefore, a suitable lower limit content of B ₂ O ₃ is 1% or more, 1.5% or more, 2% or more, 3% or more, particularly 4% or more.

The mass ratio _B 2 _O 3 / SiO ₂ is preferably 0-1 is. When the mass ratio B ₂ O ₃ / SiO ₂ increases, it becomes difficult to ensure a high liquid phase viscosity, and chemical resistance tends to decrease. Therefore, the preferable upper limit range of the mass ratio B ₂ O ₃ / SiO ₂ is 1 or less, 0.5 or less, 0.2 or less, 0.15 or less, particularly 0.13 or less. On the other hand, when the mass ratio B ₂ O ₃ / SiO ₂ is reduced, the component balance of the glass composition is impaired, the devitrification resistance is liable to decrease. Therefore, the preferable lower limit range of the mass ratio B ₂ O ₃ / SiO ₂ is 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, and particularly 0.10 or more.

The content of Al ₂ O ₃ is 0 to 15%. When the content of Al ₂ O ₃ is too large, balance of components the glass composition is impaired, the devitrification resistance is liable to decrease. Moreover, acid resistance tends to decrease. Therefore, the upper limit of the content of Al ₂ O ₃ is 15% or less, preferably 10% or less, 8% or less, and particularly 6% or less. On the other hand, when the content of Al ₂ O ₃ decreases, the viscosity of the glass is excessively lowered, and it is difficult to ensure a high liquid phase viscosity. Therefore, a suitable lower limit content of Al ₂ O ₃ is 0.5% or more, 1% or more, 2% or more, particularly 4% or more.

The content of Li ₂ O is 0 to 1% . When the content of Li ₂ O increases, the liquid phase viscosity tends to decrease and the strain point tends to decrease. In addition, the glass tends to become cloudy due to the elution of alkali components in the acid etching step. Therefore, the upper limit of the content of Li ₂ O is 1% or less , preferably less than 1 %, and it is desirable not to contain it substantially. Here, “substantially does not contain Li ₂ O” refers to a case where the content of Li ₂ O in the glass composition is less than 1000 ppm (mass).

The content of Na ₂ O is 0 to 1 %. When the content of Na ₂ O increases, the liquid phase viscosity tends to decrease and the strain point tends to decrease. In addition, the glass tends to become cloudy due to the elution of alkali components in the acid etching step. Therefore, the upper limit of the content of Na ₂ O is 1 % or less, preferably less than 1 %, and it is desirable that it is not substantially contained. Here, “substantially does not contain Na ₂ O” refers to a case where the content of Na ₂ O in the glass composition is less than 1000 ppm (mass).

The content of K ₂ O is 0 to 1 %. When the content of K ₂ O increases, the liquid phase viscosity tends to decrease and the strain point tends to decrease. In addition, the glass tends to become cloudy due to the elution of alkali components in the acid etching step. Therefore, the upper limit of the content of K ₂ O is 1 % or less, preferably less than 1 %, and it is desirable that the content is not substantially contained. Here, “substantially does not contain K ₂ O” refers to a case where the content of K ₂ O in the glass composition is less than 1000 ppm (mass).

The content of Li ₂ O + Na ₂ O + K ₂ O is preferably 0 to 1 %. When the content of Li ₂ O + Na ₂ O + K ₂ O increases, the liquid phase viscosity tends to decrease, and the strain point tends to decrease. In addition, the glass tends to become cloudy due to the elution of alkali components in the acid etching step. Therefore, the upper limit of the content of Li ₂ O + Na ₂ O + K ₂ O is 1 % or less , preferably less than 1%, and it is desirable not to contain substantially. Here, "substantially free of _{Li 2 O + Na 2 O +} K 2 O ", the content of _{Li 2 O + Na 2 O +} K 2 O in the glass composition refers to a case of less than 1000 ppm (by weight).

  The content of MgO is preferably 0 to 20%. MgO is a component that raises the refractive index nd, Young's modulus, and strain point and lowers the high-temperature viscosity. However, when MgO is contained in a large amount, the liquidus temperature rises and devitrification resistance is reduced. There is a risk that the density or thermal expansion coefficient becomes too high. Therefore, the preferable upper limit content of MgO is 20% or less, 10% or less, particularly 6% or less. On the other hand, when the content of MgO decreases, the meltability decreases, the Young's modulus decreases, and the refractive index nd tends to decrease. Therefore, a suitable lower limit content of MgO is 0.1% or more, 0.5% or more, 1% or more, 1.5% or more, 2% or more, particularly 3% or more.

  The content of CaO is preferably 0 to 11%. When the content of CaO is increased, the density and the thermal expansion coefficient are likely to be increased, and the balance of components of the glass composition is impaired, and the devitrification resistance is likely to be lowered. Therefore, the preferable upper limit content of CaO is 11% or less, 9.5% or less, and particularly 8% or less. On the other hand, when the content of CaO decreases, the meltability decreases, the Young's modulus decreases, and the refractive index nd tends to decrease. Therefore, a suitable lower limit content of CaO is 0.5% or more, 1% or more, and particularly 2% or more.

  The SrO content is preferably 2 to 25%. When the content of SrO increases, the refractive index nd, density, and thermal expansion coefficient tend to increase, and the balance of the components of the glass composition is impaired, and devitrification resistance tends to decrease. Therefore, the preferable upper limit content of SrO is 25% or less, 18% or less, 14% or less, and particularly 12% or less. On the other hand, when the content of SrO decreases, the meltability tends to decrease and the refractive index nd tends to decrease. Therefore, a suitable lower limit content of SrO is 2% or more, 5% or more, 7% or more, particularly 9% or more.

BaO is a component that increases the refractive index nd without drastically reducing the viscosity of glass among alkaline earth metal oxides, and its content is preferably 0.1 to 35 %. When the content of BaO is increased, the refractive index nd, the density, and the thermal expansion coefficient are likely to be increased, and the balance of components of the glass composition is impaired, so that the devitrification resistance is likely to be lowered. Therefore, the preferable upper limit content of BaO is 35% or less, 34% or less, and particularly 33% or less. On the other hand, when the content of BaO decreases, it becomes difficult to obtain a desired refractive index nd and it is difficult to ensure a high liquid phase viscosity. Therefore, the preferable upper limit content of BaO is 0.1% or more, 1% or more, 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, 23% or more, particularly 25% or more. .

  The content of ZnO is preferably 0 to 20%. ZnO is a component that increases the refractive index nd and strain point, and is a component that lowers the high temperature viscosity. However, when ZnO is added in a large amount, the liquidus temperature rises and devitrification resistance decreases, The density and thermal expansion coefficient may be too high. Therefore, the suitable upper limit content of ZnO is 20% or less, 10% or less, 5% or less, 3% or less, and particularly 1% or less.

The content of MgO + CaO + SrO + BaO + ZnO is 20 to 50 %. When the content of MgO + CaO + SrO + BaO + ZnO increases, the density and thermal expansion coefficient tend to increase, and the component balance of the glass composition is impaired, and devitrification resistance tends to decrease. Therefore, the upper limit of the content of MgO + CaO + SrO + BaO + ZnO is 50% or less, preferably 4 8% or less, especially 45%. On the other hand, when the content of MgO + CaO + SrO + BaO + ZnO decreases, the glass becomes unstable. Therefore, the lower limit of the content of MgO + CaO + SrO + BaO + ZnO is 20% or more, preferably 30% or more, 35% or more, particularly 40% or more.

TiO ₂ is a component that increases the refractive index nd, and its content is 0.0001 to 20%. However, when the content of TiO ₂ is increased, the component balance of the glass composition is impaired, and the devitrification resistance is easily lowered. Moreover, when the transmittance is reduced and the present invention is applied to an organic EL display, there is a possibility that the light emission efficiency is lowered. Therefore, the upper limit of the content of TiO ₂ is 20% or less, preferably 10% or less, 7% or less, particularly 5% or less. On the other hand, when the content of TiO ₂ decreases, it becomes difficult to obtain a desired refractive index nd. Therefore, the lower limit of the content of TiO ₂ is 0.0001% or more, preferably 0.001% or more, 0.01% or more, 0.02% or more, 0.05% or more, 0.1% or more, 1% or more, particularly 2% or more.

ZrO ₂ is a component that increases the refractive index nd, and its content is 0.0001 to 20%. However, when the content of ZrO ₂ increases, the component balance of the glass composition is impaired, and the devitrification resistance is likely to decrease. Therefore, the upper limit of the content of ZrO ₂ is 20% or less, preferably 10% or less, 7% or less, particularly 5% or less. On the other hand, when the content of ZrO ₂ decreases, it becomes difficult to obtain a desired refractive index nd. Therefore, the preferred lower limit content of ZrO ₂ is 0.001% or more, 0.01% or more, 0.02% or more, 0.05% or more, 0.1% or more, 1% or more, particularly 2% or more. is there.

La ₂ O ₃ is a component that increases the refractive index nd, and its content is preferably 0 to 2.5 %. When the content of La ₂ O ₃ is increased, the density and the thermal expansion coefficient are likely to be increased, and devitrification resistance and acid resistance are likely to be decreased. Moreover, raw material cost rises and the manufacturing cost of a glass plate tends to rise. Therefore, a suitable upper limit content of La ₂ O ₃ is 2 . 5% or less, particularly 1% or less.

Nb ₂ O ₅ is a component that increases the refractive index nd, and its content is preferably 0 to 10%. When the content of Nb ₂ O ₅ increases, the density and thermal expansion coefficient tend to increase, and devitrification resistance tends to decrease. Moreover, raw material cost rises and the manufacturing cost of a glass plate tends to rise. Therefore, a suitable upper limit content of Nb ₂ O ₅ is 10% or less, 5% or less, 3% or less, particularly 1% or less.

The content of Gd ₂ O ₃ is preferably 0 to 10%. Gd ₂ O ₃ is a component that increases the refractive index nd. However, if the content of Gd ₂ O ₃ increases, the density and thermal expansion coefficient become too high, the glass composition component balance is lacking, and devitrification resistance is reduced. It becomes difficult to secure a high liquid phase viscosity because the viscosity is lowered or the high temperature viscosity is excessively lowered. Therefore, a suitable upper limit content of Gd ₂ O ₃ is 10% or less, 5% or less, 3% or less, particularly 1% or less.

The content of La ₂ O ₃ + Nb ₂ O ₅ is 0 to 8 %. When the content of La ₂ O ₃ + Nb ₂ O ₅ is increased, the density and the thermal expansion coefficient are likely to be increased, the devitrification resistance is likely to be lowered, and further, it is difficult to ensure a high liquid phase viscosity. Moreover, raw material cost rises and the manufacturing cost of a glass plate tends to rise. Therefore, the upper limit of the content of La ₂ O ₃ + Nb ₂ O ₅ is 8 % or less, preferably 5 % or less, 3% or less, 1% or less, 0.5% or less, particularly 0.1% or less. .

  The total content of rare metal oxides is preferably 0 to 10%. When the content of the rare metal oxide is increased, the density and the thermal expansion coefficient are likely to be increased, and the devitrification resistance and the acid resistance are liable to be lowered, so that it is difficult to ensure a high liquid phase viscosity. Moreover, raw material cost rises and the manufacturing cost of a glass plate tends to rise. Therefore, the preferable upper limit content of the rare metal oxide is 10% or less, 5% or less, 3% or less, and particularly 1% or less.

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

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, it is preferable to refrain from using As ₂ O ₃ , Sb ₂ O ₃ , and F as much as possible from an environmental viewpoint, and each content is preferably less than 0.1%. Considering the above points, SnO ₂ , SO ₃ , Cl, and CeO ₂ are preferable as the fining agent.

The content of SnO ₂ is preferably 0 to 1%, 0.001 to 1%, particularly 0.01 to 0.5%.

The content of SO ₃ is preferably 0 to 1%, 0 to 0.5%, 0.001 to 0.1%, 0.005 to 0.1%, 0.01 to 0.1%, especially 0. 0.01-0.05%. As a material for introducing SO ₃ , sodium sulfate may be used. Moreover, you may use the raw material containing a sulfuric acid.

  The content of Cl is preferably 0 to 1%, 0.001 to 0.5%, particularly 0.01 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.

The content of CeO ₂ is preferably 0 to 6%. When the content of CeO ₂ is increased, the devitrification resistance is likely to be lowered. Therefore, the preferable upper limit content of CeO ₂ is 6% or less, 5% or less, 3% or less, 2% or less, particularly 1% or less. On the other hand, when CeO ₂ decreases, the effect as a clarifier becomes poor. Therefore, the preferable lower limit content of CeO ₂ is 0.001% or more, 0.005% or more, 0.01% or more, 0.05% or more, particularly 0.1% or more.

  PbO is a component that lowers the high-temperature viscosity, but it is preferable to refrain from using it as much as possible from an environmental point of view. The content of PbO is preferably 0.5% or less, and desirably not substantially contained. Here, “substantially does not contain PbO” refers to a case where the content of PbO in the glass composition is less than 1000 ppm (mass).

  In addition, it is possible to construct | assemble a suitable glass composition range combining the suitable containing range of each component.

  In the high refractive index glass of the present invention, the refractive index nd is 1.55 or more, preferably 1.58 or more, 1.60 or more, particularly 1.63 or more. If the refractive index nd is less than 1.55, light cannot be extracted efficiently due to reflection at the transparent conductive film-glass plate interface. On the other hand, when the refractive index nd is higher than 2.3, the reflectance at the air-glass plate interface increases, and it is difficult to extract light to the outside even if the glass surface is roughened. Therefore, the refractive index nd is 2.3 or less, preferably 2.2 or less, 2.1 or less, 2.0 or less, 1.9 or less, particularly 1.75 or less.

In the high refractive index glass of the present invention, 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. cm ³ or less, 3.5 g / cm ³ or less, particularly 3.4 g / cm ³ or less. In this way, the device can be reduced in weight.

In the high refractive index glass of the present invention, the thermal expansion coefficient at 30 to 380 ° C. is preferably 45 × 10 ^{−7 to} 110 × 10 ⁻⁷ / ° C., 50 × 10 ^{−7 to} 100 × 10 ⁻⁷ / ° C., 60 × 10 ^{−7 to} 95 × 10 ⁻⁷ / ° C., 65 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C., 65 × 10 ^{−7 to} 85 × 10 ⁻⁷ / ° C., especially 67 × 10 ⁻⁷ to 80 × 10 ⁻⁷ / ° C. In recent years, in an organic EL device or the like, flexibility may be imparted to a glass plate from the viewpoint of increasing design elements. In order to increase the flexibility of the glass plate, it is necessary to reduce the thickness of the glass plate. In this case, if the thermal expansion coefficients of the glass plate and the transparent conductive film are mismatched, the glass plate is likely to warp. Become. Therefore, if the thermal expansion coefficient at 30 to 380 ° C. is in the above range, such a situation can be easily prevented.

  In the high refractive index glass of the present invention, the strain point is preferably 600 ° C. or higher, particularly 630 ° C. or higher. In a device such as an organic thin film solar cell, when a transparent conductive film is formed, the higher the temperature, the higher the transparency and the lower the electrical resistance film can be formed. However, since conventional high refractive index glass has insufficient heat resistance, it has been difficult to achieve both transparency and low electrical resistance. Therefore, when the strain point is within the above range, in a device such as an organic thin film solar cell, both transparency and low electrical resistance can be achieved, and the glass is less likely to be thermally contracted by heat treatment in the device manufacturing process.

In the high refractive index glass of the present invention, the temperature at 10 ^2.5 dPa · s is preferably 1450 ° C. or lower, 1400 ° C. or lower, 1350 ° C. or lower, 1300 ° C. or lower, 1250 ° C. or lower, particularly 1200 ° C. or lower. If it does in this way, since meltability will improve, the manufacturing efficiency of glass will improve.

In the high refractive index glass of the present invention, the liquidus temperature is preferably 1200 ° C. or lower, 1150 ° C. or lower, 1130 ° C. or lower, 1110 ° C. or lower, 1090 ° C. or lower, 1050 ° C. or lower, 1050 ° C. or lower, 1040 ° C. or lower, 1000 ° C. Hereinafter, it is 980 degrees C or less especially. The liquid phase viscosity is preferably 10 ^3.5 dPa · s or more, 10 ^3.8 dPa · s or more, 10 ^4.0 dPa · s or more, 10 ^4.2 dPa · s or more, 10 ^4.4 dPa or more. S or more, 10 ^4.6 dPa · s or more, 10 ^4.8 dPa · s or more, particularly 10 ^5.0 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 or the overflow downdraw method.

  The high refractive index glass of the present invention is preferably plate-shaped. Further, the thickness (in the case of a plate shape) is preferably 1.5 mm or less, 1.3 mm or less, 1.1 mm or less, 0.8 mm or less, 0.6 mm or less, 0.5 mm or less, 0.3 mm or less. 0.2 mm or less, particularly 0.1 mm or less. The smaller the thickness, the higher the flexibility and the easier it is to produce a lighting device with excellent design. However, when the thickness is extremely small, the glass tends to break. Therefore, the thickness is preferably 10 μm or more, particularly 30 μm or more.

  When the high refractive index glass of the present invention is plate-shaped, it is preferable that at least one surface has an unpolished surface (particularly, the entire effective surface of at least one surface is unpolished). The theoretical strength of glass is inherently very high, but breakage often occurs even at a stress much lower than the theoretical strength. This is because a small defect called Griffith flow occurs on the glass surface in a post-molding process such as a polishing process. Therefore, if the glass surface is unpolished, the mechanical strength of the original glass is hardly impaired, and thus the glass is difficult to break. Further, since the polishing step can be simplified or omitted, 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 the unpolished 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 the transparent conductive film formed on the surface is lowered, and it becomes difficult to obtain uniform light emission.

  The high refractive index glass of the present invention is preferably formed by a down draw method, particularly an overflow down draw method. In this way, it is possible to produce a glass plate that is unpolished and has good surface quality. The reason is that, in the case of the overflow down draw method, the surface to be the surface is not in contact with the bowl-shaped refractory and is molded in a free surface state. The structure and material of the bowl-shaped structure are not particularly limited as long as desired dimensions and surface accuracy can be realized. Further, there is no particular limitation on the method for applying force to the molten glass in order to perform downward stretching. For example, a method may be adopted in which a heat-resistant roll having a sufficiently large width is rotated and stretched in contact with the molten glass, or a plurality of pairs of heat-resistant rolls are only near the end face of the molten glass. You may employ | adopt the method of making it contact and extending | stretching. In addition to the overflow downdraw method, a slot downdraw method can be employed as the downdraw method. If it does in this way, it will become easy to produce a glass plate with small board thickness. Here, the “slot down draw method” is a method of forming a glass plate by drawing and forming molten glass from a substantially rectangular gap while drawing it downward.

  The high refractive index glass of the present invention is preferably formed by a float process. In this way, a large glass plate can be produced at a low cost and in large quantities.

  In addition to the above molding method, for example, a redraw method, a float method, a roll-out method, or the like can be employed.

  The high refractive index glass of the present invention is preferably subjected to a roughening treatment on one surface by HF etching, sand blasting 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 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. Moreover, you may give uneven | corrugated shape to the glass surface (for example, heat processing, such as repress). In this way, an accurate reflection structure can be formed on the glass surface. What is necessary is just to adjust the space | interval and depth of an uneven | corrugated shape, considering the refractive index nd. Furthermore, you may affix the resin film which has an uneven | corrugated shape on the glass surface.

Further, if the surface roughening process is performed by an atmospheric pressure plasma process, the surface state of one surface can be maintained and the surface roughening process can be uniformly performed on the other surface. 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.

  Furthermore, a method of forming an uneven shape on one surface at the time of molding is also preferable. In this case, a separate roughening process becomes unnecessary, and the efficiency of the roughening process is improved.

  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.

  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.

  Tables 1-8 show Sample No. 1 to 37 are shown.

  First, after preparing a glass raw material so that it might become a glass composition as described in a table | surface, the obtained glass batch was supplied to the glass melting furnace, and it fuse | melted at 1500 degreeC for 4 hours. Next, the obtained molten glass was poured onto a carbon plate, formed into a plate shape, and then subjected to a predetermined annealing treatment. Finally, various characteristics of the obtained glass plate were evaluated.

  The refractive index nd is a 25 mm × 25 mm × about 3 mm cuboid sample, and the temperature range from (annealing point Ta + 30 ° C.) to (strain point Ps−50 ° C.) is a cooling rate of 0.1 ° C./min. This is a value measured by a refractive index measuring instrument KPR-2000 manufactured by Shimadzu Corporation while an immersion liquid in which the refractive index nd matches is permeated between the glasses.

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

  A thermal expansion coefficient 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 by 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 by 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, 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 liquidus viscosity log ₁₀ ηTL is a value obtained by measuring the viscosity of glass at the liquidus 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.

  The HCl resistance was evaluated by the following method. First, after both surfaces of each glass sample were optically polished, a part thereof was masked, and then chemical treatment was performed under the following conditions. After the chemical treatment, the mask was removed, and the level difference between the mask portion and the erosion portion was measured with a surface roughness meter, and the value was taken as the erosion amount. The HCl resistance (erosion amount) is evaluated as “X” when the erosion amount exceeds 20 μm, and “◯” when the erosion amount is 20 μm or less. For HCl resistance (appearance), after both surfaces of each glass sample are optically polished and treated with chemicals under the following conditions, the surface of the glass sample is visually observed to become cloudy, rough, or cracked Is evaluated as “×”, and no change is evaluated as “◯”.

  The treatment conditions for HCl resistance (erosion amount) are immersed in a 10% by mass HCl aqueous solution at 80 ° C. for 24 hours, and the treatment conditions for HCl resistance (appearance) are immersed in a 10% by mass HCl aqueous solution at 80 ° C. for 24 hours. It is.

As is apparent from the table, sample No. 1 to 36 substantially did not contain an alkali component and a rare metal oxide, had a refractive index nd of 1.623 or more, and had good acid resistance. Sample No. 1, 5, 8-18, 20, 24-26, and 28-36 had a liquidus viscosity of ^103.4 dPa · s or more. Furthermore, sample no. Since Nos. 1 to 12 have a low refractive index nd and a low density, the device can be reduced in weight. Moreover, since it approximates the thermal expansion coefficient of the transparent conductive film, it is expected that the warpage of the glass plate can be suppressed. Sample No. Since 1-6 and 8-36 have a high strain point, it is thought that the thermal contraction of the glass in the manufacturing process of a device can be suppressed. On the other hand, sample No. No. 37 contained a large amount of rare metal oxide in the glass composition, so that the density was high and the acid resistance was low.

The high refractive index glass of the present invention has a refractive index nd of 1.55 or more and a high liquidus viscosity. And from a viewpoint of raw material cost, it is possible to remove a rare metal oxide from the glass composition, and from an environmental viewpoint, it is also possible to remove As ₂ O ₃ , Sb ₂ O _{3 and the} like from the glass composition. Therefore, the high refractive index glass of the present invention is suitable for an organic EL device substrate, particularly an organic EL lighting substrate. The high refractive index glass of the present invention includes a flat panel display substrate such as a liquid crystal display, a cover glass of an image sensor such as a charge coupled device (CCD) and a 1 × close proximity solid-state imaging device (CIS), and a substrate for a solar cell. Etc. can also be used.

Claims (7)

As a glass composition, in _{mass%, SiO 2 35~60%, B} 2 O 3 1~15%, Al 2 O 3 0~15%, Li 2 O 0~1%, Na 2 O 0~1%, K _{2 O 0~1%, Li 2 O} + Na 2 O + K 2 O 0~1%, CaO 0~11%, SrO 2~25%, BaO 0.1~35%, MgO + CaO + SrO + BaO + 20~50% ZnO, TiO 2 0.0001 _{~20%, ZrO 2 0.0001~20%,} La 2 O 3 0~2.5%, La 2 O 3 + Nb 2 O 5 containing 0-8% and the refractive index nd of 1.55 to 2. 3. A high refractive index glass characterized by being 3. The high refractive index glass according to claim 1 , comprising 3% by mass or more of B ₂ O ₃ . High refractive index glass according to claim 1 or 2, characterized in that it comprises MgO 1 mass% or more. The high refractive index glass according to any one of claims 1 to 3 , wherein the glass has a plate shape. Liquid phase viscosity is 10 < ^3.0 > dPa * s or more, The high refractive index glass as described in any one of Claim 1 thru | or 4 characterized by the above-mentioned. The high refractive index glass according to any one of claims 1 to 5 , wherein the glass has an unpolished surface on at least one surface, and the surface roughness Ra of the surface is 10 mm or less. It is a manufacturing method of the high refractive index glass as described in any one of Claims 1 thru | or 6 , Comprising:
A method for producing a high refractive index glass, which is formed into a plate shape by a float method or a downdraw method.