JP6175742B2 - High refractive index glass - Google Patents

Description

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

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

JP 2007-149460 A

  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 ITO is 1.9 to 2.0. On the other hand, the refractive index nd of the glass substrate is usually about 1.5. For this reason, the conventional organic EL device has a problem that it has a high reflectance due to the difference in refractive index at the glass substrate-ITO interface, and the light generated from the organic light emitting element cannot be extracted efficiently.

With respect to the above problem, the light extraction efficiency can be improved by increasing the refractive index nd of the glass substrate. However, when a large amount of rare metal oxide such as La ₂ O ₃ , Nb ₂ O ₅ , Gd ₂ O ₃ is added to the glass composition in order to increase the refractive index nd of the glass substrate, the devitrification resistance is likely to be lowered. In addition, mass production becomes difficult and the cost of raw materials increases.

  Therefore, the present invention has a technical problem to create a high refractive index glass that matches the refractive index nd of organic light emitting devices and ITO, has high devitrification resistance, and can prevent a rise in raw material costs. .

As a result of intensive studies, the present inventors have found that the above technical problem can be solved by regulating the content range and refractive index of each component to a predetermined range, and propose the present invention. is there. That is, the high refractive index glass of the present invention is, as a glass composition, in mass%, SiO ₂ 10 to 55%, B ₂ O _{30 to} 5 %, SrO 0.001 to 35%, TiO ₂ 1 to 12%, _{ZrO 2 + TiO 2 1 ~30%} , La 2 O 3 0~2%, La 2 O 3 + Nb 2 O 5 0~ containing 5% weight ratio BaO / SrO is 0 to 40, the weight ratio _SiO 2 / SrO Is 0.1 to 40, and the refractive index nd is 1.55 to 2.3. Here, “ZrO ₂ + TiO ₂ ” refers to the total amount of ZrO ₂ and TiO ₂ . “La ₂ O ₃ + Nb ₂ O ₅ ” refers to the total amount of La ₂ O ₃ and Nb ₂ O ₅ . “Refractive index nd” can be measured with a commercially available refractive index measuring device. For example, after a rectangular parallelepiped sample of 25 mm × 25 mm × about 3 mm is prepared, the temperature range from (Ta + 30 ° C.) to (strain point−50 ° C.) Is measured by using a refractive index measuring instrument KPR-2000 manufactured by Shimadzu Corporation in a state where an immersion liquid in which the refractive index is matched is infiltrated between the glasses at a cooling rate of 0.1 ° C./min. Is possible. “Strain point” refers to a value measured based on ASTM C336-71.

The high refractive index glass of the present invention preferably has a liquidus viscosity of 10 ^3.0 dPa · s or more. Here, “liquid phase viscosity” refers to a value obtained by measuring the viscosity of glass at the liquid phase temperature by a platinum ball pulling method. “Liquid phase temperature” refers to the temperature at which crystals precipitate after passing through a standard sieve 30 mesh (500 μm), 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 high refractive index glass of the present invention is preferably plate-shaped. Here, “plate shape” is not interpreted in a limited way, and includes a film shape with a small plate thickness, for example, a film-shaped glass placed along a cylinder, and an uneven shape is formed on one surface. Including.

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

The high refractive index glass of the present invention preferably has a temperature at 10 ⁴ dPa · s of 1250 ° C. or lower. Here, “temperature at 10 ^4.0 dPa · s” refers to a value measured by a platinum ball pulling method.

The high refractive index glass of the present invention preferably has a strain point of 650 ° C. or higher.

The high refractive index glass of the present invention is preferably used for an illumination device.

The high refractive index glass of the present invention is preferably used for organic EL lighting.

The high refractive index glass of the present invention is preferably used for an organic EL display.

The high refractive index glass of the present invention is, as a glass composition, in mass%, SiO ₂ 10 to 55%, B ₂ O _{30 to} 5 %, SrO 0.001 to 35%, ZnO 0 to 12%, TiO ₂ 1 to 1 % . _{12%, ZrO 2 + TiO 2} 1 ~30%, La 2 O 3 0~2%, La 2 O 3 + Nb 2 O 5 0~5%, Li 2 O + Na 2 O + K 2 contain O 0%, by weight The ratio BaO / SrO is 0 to 20, the mass ratio SiO ₂ / SrO is 0.1 to 20, the mass ratio (MgO + CaO) / SrO is 0 to 20, the refractive index nd is 1.58 or more, and the liquid phase viscosity is 10. It is characterized by being ^3.5 dPa · s or more and a strain point of 670 ° C. or more. Here, “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. “MgO + CaO” refers to the total amount of MgO and CaO.

The high refractive index glass of the present invention is, as a glass composition, in mass%, SiO ₂ 10 to 50%, Al ₂ O ₃ 0.5 to 20%, B ₂ O ₃ 0 to 5 %, CaO 0 to 10%, _{SrO 0.001~35%, BaO 0~30%,} 0~4% ZnO, TiO 2 1~12%, ZrO 2 + TiO 2 1 ~30%, La 2 O 3 0~2%, La 2 O 3 + Nb ₂ O ₅ 0-5%, Li ₂ O + Na ₂ O + K ₂ O 0-2%, mass ratio BaO / SrO is 0-20, mass ratio SiO ₂ / SrO is 1-15, mass ratio (MgO + CaO) / The SrO is 0 to 20, the refractive index nd is 1.6 or more, the liquid phase viscosity is 10 ^4.0 dPa · s or more, and the strain point is 670 ° C. or more.

In the high refractive index glass of the present invention, the content of B ₂ O ₃ is preferably 0 to 3% by mass.

In the high refractive index glass of the present invention, the MgO content is preferably 0 to 3% by mass.

In the high refractive index glass of the present invention, the content of ZrO ₂ + TiO ₂ is preferably 1 to 20% by mass.

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

  The reason why the content range of each component is limited as described above in the high refractive index glass of the present invention will be described below. In addition, in description of the following content ranges,% display represents the mass% except the case where there is particular notice.

The content of B ₂ O ₃ is preferably 0 to 5 %. When the content of B ₂ O ₃ increases, the refractive index nd and Young's modulus tend to decrease. Therefore, a preferable upper limit range of B ₂ O ₃ is 4 % or less, 3% or less, less than 2%, 1% or less, particularly less than 1%.

  The SrO content is preferably 0.001 to 35%. SrO is a component having a large effect of increasing the refractive index nd while relatively suppressing devitrification among alkaline earth metal oxides. However, when the content of SrO increases, the refractive index nd, density, and thermal expansion coefficient increase, and the component balance of the glass composition is lacking, and the devitrification resistance tends to decrease. Therefore, the preferable upper limit range of SrO is 30% or less, 25% or less, 20% or less, 15% or less, 12% or less, 10% or less, and particularly 8% or less. A preferable lower limit range of SrO is 0.01% or more, 0.1% or more, 1% or more, 2% or more, 3% or more, 3.5% or more, particularly 4% or more.

The content of TiO ₂ + ZrO ₂ is preferably 1 to 30%. When the content of TiO ₂ + ZrO ₂ increases, the devitrification resistance tends to be lowered, and the density and the thermal expansion coefficient may become too high. On the other hand, when the content of TiO ₂ + ZrO ₂ decreases, the refractive index nd tends to decrease. Therefore, the preferable upper limit range of TiO ₂ + ZrO ₂ is 25% or less, 20% or less, 18% or less, 15% or less, 14% or less, particularly 13% or less. A preferable lower limit range of TiO ₂ + ZrO ₂ is 3 % or more, 5% or more, 6% or more, particularly 7% or more.

The content of TiO ₂ is preferably 1 to 12 %. TiO ₂ is a component that increases the refractive index nd. However, when the content of TiO ₂ increases, the density and thermal expansion coefficient become too high, the devitrification resistance tends to decrease, or the transmittance tends to decrease. Therefore, a suitable upper limit range of TiO ₂ is 8 % or less. A suitable lower limit range of TiO ₂ is 3 % or more.

The content of ZrO ₂ is preferably 0 to 30%. ZrO ₂ is a component that has a large effect of increasing the refractive index nd and increasing the viscosity near the liquidus temperature. However, when the content of ZrO ₂ increases, the density and the density become too high, and the devitrification resistance is liable to decrease. Therefore, the preferable upper limit range of ZrO ₂ is 15% or less, 10% or less, 7% or less, and particularly 6% or less. A suitable lower limit range of ZrO ₂ is 0.001% or more, 0.01% or more, 0.5% or more, 1% or more, 2% or more, particularly 3% or more.

The content of La ₂ O ₃ + Nb ₂ O ₅ is preferably 0 to 5 %. When the content of _{La 2 O 3 + Nb 2 O} 5 is increased, but easily refractive index nd is higher, and the content is multi Kunar, lacks component balance of the glass composition, the devitrification resistance is lowered, There is a risk that the raw material cost will rise and the glass production cost will rise. In particular, in applications such as lighting, an inexpensive glass is required, so that the raw material cost is not increased. Therefore, a suitable lower limit range of La ₂ O ₃ + Nb ₂ O ₅ is 3 % or less, 2% or less, 1% or less, 0.5% or less, particularly 0.1% or less.

La ₂ O ₃ is a component that increases the refractive index nd. When the content of La ₂ O ₃ increases, the devitrification resistance tends to decrease, and the density and thermal expansion coefficient may become too high. Therefore, the content of La ₂ O ₃ is preferably 2 % or less, 1% or less, 0.5% or less, and particularly preferably 0.1% or less.

Nb ₂ O ₅ is a component that increases the refractive index nd. When the content of Nb ₂ O ₅ increases, the devitrification resistance tends to decrease, and the density and thermal expansion coefficient may become too high. Therefore, the content of Nb ₂ O ₅ is preferably 5 % or less, 2% or less, 1% or less, 0.5% or less, particularly preferably 0.1% or less.

Mass ratio _{(La 2 O 3 + Nb 2} O 5) / (ZrO 2 + TiO 2) 0 to 30 is preferred. As the mass ratio (La ₂ O ₃ + Nb ₂ O ₅ ) / (ZrO ₂ + TiO ₂ ) is larger, it is possible to increase the refractive index nd while suppressing a decrease in devitrification resistance. If too much, the balance of the components of the glass composition is lost, devitrification resistance is lowered, and the raw material cost is too high. Therefore, the preferable upper limit range of the mass ratio (La ₂ O ₃ + Nb ₂ O ₅ ) / (ZrO ₂ + TiO ₂ ) is 20 or less, 10 or less, 5 or less, 2 or less, 1 or less, 0.1 or less, especially 0. 01 or less.

  The mass ratio BaO / SrO is 0-40. If the mass ratio BaO / SrO is too large, the devitrification resistance may decrease, or the density and the thermal expansion coefficient may become too high. On the other hand, if the mass ratio BaO / SrO is too small, the refractive index nd may be reduced, or the component balance of the glass composition may be lost, and the devitrification resistance may be reduced. Therefore, a preferable upper limit range of the mass ratio BaO / SrO is 30 or less, 20 or less, 10 or less, 8 or less, and particularly 5 or less. A preferable lower limit range of the mass ratio BaO / SrO is 0.1 or more, 0.5 or more, 1 or more, 2.5 or more, particularly 3 or more.

  BaO is a component that increases the refractive index nd without extremely reducing the viscosity of the glass among alkaline earth metal oxides, and its content is preferably 0 to 40%. When the content of BaO increases, the refractive index nd, density, and thermal expansion coefficient tend to increase. However, when the content of BaO exceeds 40%, the component balance of the glass composition is lacking, and the devitrification resistance tends to decrease. Therefore, the preferable upper limit range of BaO is 35% or less, 32% or less, 30% or less, 29.5% or less, 29% or less, and particularly preferably 28% or less. However, 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 lower limit range of BaO is 0.5% or more, 1% or more, 2% or more, 5% or more, 10% or more, 15% or more, 17% or more, 20% or more, 23% or more, particularly 25%. The above is preferable.

Weight ratio _SiO 2 / SrO is 0.1 to 40. If the mass ratio SiO ₂ / SrO is too large, the refractive index nd tends to decrease. On the other hand, if the mass ratio SiO ₂ / SrO is too small, the devitrification resistance tends to decrease, and the density and the thermal expansion coefficient may become too high. Therefore, a preferable upper limit range of the mass ratio SiO ₂ / SrO is 30 or less, 20 or less, 15 or less, 10 or less, 9 or less, and particularly 8 or less. A preferable lower limit range of the mass ratio SiO ₂ / SrO is 0.5 or more, 1 or more, 2 or more, 2.5 or more, particularly 3 or more.

The content of SiO ₂ is preferably 10 to 55 %. 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. Thus, the content of SiO ₂ is 3% or less, 52% or less, 50% or less, 49% or less, 48% or less, particularly preferably 45%. On the other hand, when the content of SiO ₂ decreases, it becomes difficult to form a glass network structure, and vitrification becomes difficult. Further, the viscosity of the glass is excessively lowered, and it becomes difficult to ensure a high liquid phase viscosity. Thus, the content of SiO ₂ is 1 to 5% or more, 20% or more, 25% or higher, 30% or more, 35% or more, particularly 40% or more.

The content of Al ₂ O ₃ is preferably 0 to 20%. When the content of Al ₂ O ₃ is increased, devitrified crystals are likely to be precipitated on the glass, the liquid phase viscosity is likely to be lowered, and the refractive index nd is liable to be lowered. Therefore, the preferable upper limit range of Al ₂ O ₃ is 15% or less, 10% or less, 8% or less, and particularly 6% or less. Incidentally, the content of Al ₂ O ₃ is reduced, lacks component balance of the glass composition, the glass is liable to devitrify reversed. Therefore, a preferable lower limit range of Al ₂ O ₃ is 0.1% or more, 0.5% or more, 1% or more, particularly 3% or more.

  The content of MgO is preferably 0 to 10%. MgO is a component that increases the refractive index nd, Young's modulus, and strain point, and also decreases the high-temperature viscosity. However, when a large amount of MgO is added, the liquidus temperature increases and the devitrification resistance decreases. Or the density and thermal expansion coefficient may become too high. Therefore, a suitable upper limit range of MgO is 5% or less, 3% or less, 2% or less, 1.5% or less, 1% or less, particularly 0.5% or less.

  The content of CaO is preferably 0 to 10%. When the content of CaO increases, the density and the thermal expansion coefficient tend to be high, and when the content of CaO is too large, the component balance of the glass composition is lacking and the devitrification resistance tends to decrease. Therefore, the preferable upper limit range of CaO is 9% or less, particularly 8.5% or less. Note that when the content of CaO decreases, the meltability decreases, the Young's modulus decreases, and the refractive index nd tends to decrease. Therefore, the preferable lower limit range of CaO is 0.5% or more, 1% or more, 2% or more, 3% or more, particularly 4% or more.

  The mass ratio (MgO + CaO) / SrO is preferably 0-20. When the mass ratio (MgO + CaO) / SrO increases, it is possible to reduce the density of the glass and reduce the high-temperature viscosity while maintaining a high refractive index nd, but the liquidus temperature tends to be high, and the high liquidus It becomes difficult to maintain the viscosity. Therefore, a suitable upper limit range of the mass ratio (MgO + CaO) / SrO is 10 or less, 8 or less, 5 or less, 3 or less, 2 or less, particularly 1 or less.

  The content of ZnO is preferably 0 to 12%. When the content of ZnO increases, the density and thermal expansion coefficient become too high, the balance of the composition of the glass composition is lacking, the devitrification resistance is lowered, the high temperature viscosity is lowered too much, and the high liquidus viscosity is increased. It becomes difficult to secure. Therefore, the preferable upper limit range of ZnO is 8% or less, 4% or less, 2% or less, 1% or less, 0.5% or less, 0.1% or less, particularly 0.01% or less.

The content of La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ is preferably 0 to 10%. When the content of La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ increases, the refractive index nd tends to increase. However, when the content exceeds 10%, the glass composition lacks the component balance and is devitrification resistant. There is a risk that the manufacturing cost of the glass will rise due to a decrease in properties or a rise in raw material costs. In particular, in applications such as lighting, an inexpensive glass is required, so that the raw material cost is not increased. Therefore, a suitable lower limit range of La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ is 9% or less, 8% or less, 5% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, In particular, it is 0.1% 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. 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, the preferable upper limit range of Gd ₂ O ₃ is 8% or less, 4% or less, 2% or less, 1% or less, 0.5% or less, 0.1% or less, particularly 0.01% or less.

The content of Li ₂ O + Na ₂ O + K ₂ O is preferably 0 to 15%. Li ₂ O + Na ₂ O + K ₂ O is a component that lowers the viscosity of the glass and adjusts the thermal expansion coefficient. However, when a large amount of Li ₂ O + Na ₂ O + K ₂ O is added, the viscosity of the glass decreases. Thus, it becomes difficult to ensure a high liquid phase viscosity. Therefore, the preferable upper limit range of Li ₂ O + Na ₂ O + K ₂ O is 10% or less, 5% or less, 2% or less, 1.5% or less, 1% or less, 0.5% or less, particularly 0.1% or less. is there.

As a fining agent, 0 to 3% of one or two or more selected from the group of As ₂ O ₃ , Sb ₂ O ₃ , CeO ₂ , SnO ₂ , F, Cl, and SO ₃ can be added. However, As ₂ O ₃ , Sb ₂ O ₃ , and F, particularly As ₂ O ₃ and Sb ₂ O ₃ , it is preferable to refrain from using them as much as possible from an environmental viewpoint, and each content is 0.1%. Less than is preferable. Considering the above points, SnO ₂ , SO ₃ , and Cl are preferable as the fining agent. In particular, the SnO ₂ content is preferably 0 to 1%, 0.01 to 0.5%, particularly preferably 0.05 to 0.4%. The content of SnO ₂ + SO ₃ + Cl is preferably 0 to 1%, 0.001 to 1%, 0.01 to 0.5%, and particularly preferably 0.01 to 0.3%. Here, “SnO ₂ + SO ₃ + Cl” refers to the total amount of SnO ₂ , SO ₃ , and Cl.

  PbO is a component that lowers the high temperature viscosity, but it is preferable to refrain from using it as much as possible from the environmental viewpoint, and its content is preferably 0.5% or less, and more preferably less than 1000 ppm (mass).

Bi ₂ O ₃ is a component that lowers the high temperature viscosity, but it is preferable to refrain from using it as much as possible from the environmental viewpoint, and its content is preferably 0.5% or less, more preferably less than 1000 ppm (mass). .

  Of course, it is possible to construct a suitable glass composition range by combining preferred ranges of each component, but among them, particularly preferred from the viewpoint of refractive index nd, devitrification resistance, production cost, etc. The glass composition range is as follows.

  In the high refractive index glass of the present invention, the refractive index nd is 1.55 or more, preferably 1.58 or more, 1.6 or more, 1.63 or more, 1.65 or more, particularly 1.66 or more. When the refractive index nd is less than 1.55, the reflectance at the ITO-glass interface increases, and light cannot be extracted efficiently. On the other hand, when the refractive index nd exceeds 2.3, the reflectance at the air-glass interface increases, and it becomes difficult to increase the light extraction efficiency even if the glass surface is roughened. Therefore, the refractive index nd is preferably 2.3 or less, 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 liquidus temperature is preferably 1200 ° C. or lower, 1150 ° C. or lower, 1130 ° C. or lower, 1110 ° C. or lower, 1090 ° C. or lower, 1070 ° C. or lower, particularly 1050 ° C. or lower. Further, the liquid phase viscosity is 10 ^3.0 dPa · s or more, 10 ^3.5 dPa · s or more, 10 ^3.8 dPa · s or more, 10 ^4.0 dPa · s or more, 10 ^4.1 dPa · s or more. It is preferably 10 ^4.2 dPa · s or more, particularly preferably 10 ^4.3 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 glass process.

  The high refractive index glass of the present invention is preferably plate-shaped. The thickness is preferably 1.5 mm or less, 1.3 mm or less, 1.1 mm or less, 0.8 mm or less, 0.6 mm or less, 0.5 mm or less, 0.3 mm or less, particularly 0.2 mm or less. The smaller the plate thickness, the higher the flexibility and the easier it is to improve the design of the lighting device. However, when the plate thickness becomes extremely small, the glass plate is easily broken. Therefore, the plate thickness is preferably 10 μm or more, particularly 30 μm or more.

  The high refractive index glass of the present invention is preferably formed by a float process. In this way, it is possible to manufacture a glass plate that is unpolished and has good surface quality at a low cost and in large quantities.

  In addition to the float method, for example, a downdraw method (overflow downdraw method, slot downdraw method, redraw method, etc.), rollout method, or the like can be employed as a method for forming a glass plate.

  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 by 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.

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

  In addition, when forming a non-reflective structure on the glass surface at the time of shaping | molding, the same effect can be enjoyed even if it does not roughen.

In the high refractive index glass of the present invention, the density is 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. In particular, 3.5 g / cm ³ or less is preferable. If it does in this way, glass will be reduced in weight and a device can be reduced in weight. The “density” can be measured by a known Archimedes method.

In the high refractive index glass of the present invention, the thermal expansion coefficient is 30 × 10 ^{−7 to} 100 × 10 ⁻⁷ / ° C., 40 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C., 60 × 10 ^{−7 to} 85 × 10. ⁻⁷ / ° C., 65 × 10 ⁻⁷ to 80 × 10 ⁻⁷ / ° C., 68 × 10 ^{−7 to} 78 × 10 ⁻⁷ / ° C., particularly 70 × 10 ^{−7 to} 78 × 10 ⁻⁷ / ° C. are preferable. In recent years, in an organic EL lighting, an organic EL device, and a dye-sensitized solar cell, a flexible glass plate is required from the viewpoint of enhancing design elements. In order to increase the flexibility of the glass plate, it is necessary to reduce the thickness of the glass plate. In this case, the thermal expansion coefficients of the glass plate and the transparent conductive film such as ITO, FTO, etc. are inconsistent. The glass plate tends to warp. Further, when an organic EL display using an oxide TFT is manufactured, if the thermal expansion coefficients of the oxide TFT and the glass plate are mismatched, the glass plate is warped or the oxide TFT film is cracked. May enter. Therefore, if the thermal expansion coefficient is in the above range, such a situation can be easily prevented. Here, the “thermal expansion coefficient” refers to an average value in a temperature range of 30 to 380 ° C., and can be measured, for example, with a dilatometer.

  In the high refractive index glass of the present invention, the strain point is preferably 630 ° C. or higher, 650 ° C. or higher, 670 ° C. or higher, 690 ° C. or higher, particularly 700 ° C. or higher. If it does in this way, it will become difficult to heat-shrink glass by the high temperature heat processing in the manufacturing process of a device. In particular, when an organic EL display is manufactured using an oxide TFT or the like, a heat treatment of about 600 ° C. is necessary to stabilize the quality of the oxide TFT. If the strain point is regulated as described above, In this heat treatment, the thermal shrinkage of the glass can be reduced.

In the high refractive index glass of the present invention, the temperature at 10 ^2.5 dPa · s is preferably 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 glass excellent in foam quality will be easy to be obtained, and the manufacture efficiency of a glass plate will improve.

In the high refractive index glass of the present invention, the temperature at 10 ^4.0 dPa · s is 1250 ° C. or lower, 1200 ° C. or lower, 1150 ° C. or lower, 1110 ° C. or lower, particularly 1060 ° C. or lower. In this way, the molding temperature can be lowered in the molding by the float method. As a result, low-temperature operation becomes possible, and the refractory used in the molded part has a long life, and the manufacturing cost of the glass plate is likely to decrease.

  If the manufacturing method of the high refractive index glass of this invention is illustrated, a glass raw material will be first prepared and a glass batch will be produced so that it may become a desired glass composition. Next, after the glass batch is melted and clarified, the obtained molten glass is formed into a desired shape. Then, if necessary, an annealing process is performed to process 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.

Table 1-4, specimen No. 1 to 19 are shown.

  First, after preparing a glass raw material so that it might become a glass composition of Tables 1-4, the obtained glass batch was supplied to the glass melting furnace, and it fuse | melted at 1500-1600 degreeC for 4 hours. Next, after the obtained molten glass was poured out on a carbon plate and formed into a plate shape, a predetermined annealing treatment was performed. Finally, various characteristics of the obtained glass plate were evaluated.

  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 based on ASTM C336-71. In addition, heat resistance becomes high, so that the strain point Ps is high.

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

The temperature at 10 ^4.0 dPa · s, the temperature at 10 ^3.0 dPa · s, and the temperature at 10 ^2.5 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), puts the glass powder remaining in 50 mesh (300 μm) into a platinum boat, holds it in a temperature gradient furnace for 24 hours, and then measures the temperature at which crystals precipitate. It is the value. Further, the liquidus viscosity log ₁₀ ηTL indicates 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.

  Refractive index nd is 25 mm × 25 mm × about 3 mm cuboid sample, and then annealed in the temperature range from (Ta + 30 ° C.) to (Ps−50 ° C.) at a cooling rate of 0.1 ° C./min. The value measured with a refractive index measuring instrument KPR-2000 manufactured by Shimadzu Corporation using an immersion liquid having a matching refractive index.

  Sample No. After preparing a glass raw material so that it might become the glass composition of 3 described, the obtained glass batch was thrown into the continuous kiln, and it fuse | melted at the temperature of 1500-1600 degreeC. Subsequently, the obtained molten glass was molded by a float process to obtain a glass plate having a thickness of 0.5 mm.

  Sample No. After preparing a glass raw material so that it might become the glass composition of 4th, the obtained glass batch was thrown into the continuous kiln, and it fuse | melted at the temperature of 1500-1600 degreeC. Subsequently, the obtained molten glass was molded by a float process to obtain a glass plate having a thickness of 0.5 mm.

  Sample No. After preparing a glass raw material so that it might become the glass composition of 6th, the obtained glass batch was thrown into the continuous kiln, and it fuse | melted at the temperature of 1500-1600 degreeC. Subsequently, the obtained molten glass was molded by a float process to obtain a glass plate having a thickness of 0.5 mm.

Claims (11)

As a glass composition, in _{mass%, SiO 2 10~50%, Al} 2 O 3 0.5~20%, B 2 O 3 0~5%, CaO 0~10%, SrO 2~35%, BaO 10~ _{40%, TiO 2 1~12%,} ZrO 2 0.001~15%, ZrO 2 + TiO 2 3 ~ 25%, La 2 O 3 0~2%, La 2 O 3 + Nb 2 O 5 0~5%, Li ₂ O + Na ₂ O + K ₂ O 0 to 0.1% is contained, the mass ratio BaO / SrO is 0.5 to 20, the mass ratio SiO ₂ / SrO is 1 to 15, and the refractive index nd is 1.55. A high refractive index glass having a refractive index of 2.3. Furthermore, the high refractive index glass of claim 1 in which the content of B ₂ O ₃ is characterized in that it is a 0-3% by weight. Furthermore, MgO content is 0-3 mass%, The high refractive index glass of Claim 1 or 2 characterized by the above-mentioned. 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. 10 ^4.0 high refractive index glass according to claims 1 to 5 Temperature in dPa · s is equal to or is 1250 ° C. or less. The high refractive index glass according to any one of claims 1 to 6 , wherein the strain point is 650 ° C or higher. High refractive index glass according to any one of claims 1 to 7, characterized by using the lighting device. The high refractive index glass according to claim 8 , which is used for organic EL lighting. High refractive index glass according to any one of claims 1 to 7, characterized by using the organic EL display. A method for producing the high refractive index glass according to any one of claims 1 to 10 ,
A method for producing a high refractive index glass, which is formed into a plate shape by a float method or a downdraw method.