Glass

Abstract

Glass according to the present invention is characterized by having a glass composition containing, by mass%: 50-70% of SiO2; 15-25% of Al2O3; 1-5% of B2O3; 0-0.5% of Li2O+Na2O+K2O; 0-5% of MgO; 0-10% of CaO; 0-5% of SrO; and 0-10% of BaO.

Description

Glass

[0001] The present invention relates to glass, and more particularly to glass used for an alkali-free glass plate suitable for an organic EL display.

[0002] 2. Description of the Related Art Electronic devices such as organic EL displays are thin, have excellent moving image display capabilities, and consume low power, and are therefore used in applications such as flexible devices and displays for mobile phones.

[0003] Glass plates are widely used as substrates for organic electroluminescence (EL) displays. Glass plates for this application are primarily required to have the following properties: (1) They must contain almost no alkali metal oxides, i.e., be alkali-free glass (the content of alkali metal oxides in the glass composition must be 0.5% by mass or less), in order to prevent alkali ions from diffusing into the semiconductor material formed in the heat treatment process; (2) They must be highly productive, particularly in terms of melting properties and devitrification resistance, in order to reduce the cost of the glass plate; and (3) They must have a high strain point in order to reduce thermal shrinkage of the glass plate in the LTPS (low temperature polysilicon) process.

[0004] Japanese Patent Application Laid-Open No. 2022-116123

[0005] Organic EL devices are also widely used in organic EL televisions. The panel size of organic EL televisions is significantly larger than that of mobile products. It is expected that there will be a growing demand for larger and thinner glass plates in the future. The larger and thinner the glass plate, the more likely it is to warp, which increases the likelihood of various defects occurring.

[0006] Glass sheets formed by glass manufacturers undergo processes such as cutting, annealing, inspection, and cleaning. During these processes, the glass sheets are loaded into and removed from cassettes with multiple shelves. This cassette is usually designed so that opposing edges of the glass sheet can be placed on shelves formed on the left and right inner surfaces and held horizontally. However, large, thin glass sheets tend to bend significantly, so when the glass sheet is loaded into the cassette, part of the glass sheet may come into contact with the cassette and be damaged, or when the glass sheet is removed, it may swing significantly and become unstable. Cassettes of this type are also used by electronic device manufacturers, and similar problems occur.

[0007] Furthermore, as organic EL devices become larger and thinner, the glass plate becomes more likely to bend, which can cause the image surface of an organic EL television to appear distorted. Also, as the definition increases, the thickness of the metal film formed on the glass substrate must be increased, and the stress generated in the film makes the glass more susceptible to deformation.

[0008] To solve this problem, it is effective to increase the Young's modulus of the glass plate to reduce the amount of deflection.

[0009] Furthermore, as described above, in the LTPS process, it is necessary to increase the strain point of the glass sheet in order to reduce the thermal shrinkage of the glass sheet.

[0010] However, attempts to increase the Young's modulus and strain point of a glass sheet disrupt the balance of the glass composition, resulting in a decrease in meltability and devitrification resistance, which in turn tends to reduce the productivity of the glass sheet, resulting in a rise in the cost of the glass sheet raw material.

[0011] The present invention has been made in view of the above circumstances, and its technical object is to provide a glass which is excellent in productivity and has a sufficiently high strain point and Young's modulus.

[0012] As a result of repeated various experiments, the present inventors have found that the above technical problems can be solved by strictly controlling the glass composition, and have proposed this as the present invention. ２ 50-70%, Al ２ O ３15-25%, B ２ O ３ 1-5% Li ２ O + Na ２ O+K ２ It is characterized by containing 0 to 0.5% of O, 0 to 5% of MgO, 0 to 10% of CaO, 0 to 5% of SrO, and 0 to 10% of BaO. ２ O + Na ２ O+K ２ "O" is Li ２ O, Na ２ O and K ２ It refers to the total mass % content of O.

[0013] The glass of the present invention contains, in mass %, SiO ２ 57-62.5%, Al ２ O ３ 17-19.5%, B ２ O ３ It is preferable that the composition contains 1.1 to 2.8% of MgO, 2 to 5% of MgO, 3.7 to 6% of CaO, 0 to 4.5% of SrO, 0 to 8% of BaO, and 17.5% or more of MgO + CaO + SrO + BaO, with a mass percent ratio of MgO / CaO of 0.68 or more. Here, "MgO + CaO + SrO + BaO" refers to the total mass percent contents of MgO, CaO, SrO, and BaO. The "mass percent ratio MgO / CaO" is the value obtained by dividing the mass percent content of MgO by the mass percent content of CaO.

[0014] In addition, the glass of the present invention has a mass % ratio (MgO+CaO+SrO+BaO) / Al ２ O ３ It is preferable that the mass % ratio (MgO+CaO+SrO+BaO) / Al is 0.70 to 1.70. ２ O ３ " is the total mass% content of MgO, CaO, SrO and BaO in percent by weight of Al ２ O ３ The value was calculated by dividing the content by mass%.

[0015] The glass of the present invention preferably has a Young's modulus of 78 GPa or more, a strain point of 680°C or more, and a liquidus temperature of 1450°C or less. "Young's modulus" refers to a value measured by a bending resonance method. 1 GPa is approximately 101.9 kgf / mm２ The "strain point" refers to a value measured based on the method of ASTM C336. The "liquidus temperature" refers to the temperature at which crystals precipitate when a glass powder that passes through a 30 mesh (500 μm) standard sieve and remains on a 50 mesh (300 μm) sieve is placed in a platinum boat and held in a temperature gradient furnace for 24 hours.

[0016] The glass of the present invention further contains SnO ２ It is preferable that the content be 0.001 to 1 mass %.

[0017] The glass of the present invention preferably has a strain point of 690° C. or higher.

[0018] The glass of the present invention preferably has a Young's modulus of more than 80 GPa.

[0019] The glass of the present invention has an average thermal expansion coefficient of 30×10 in the temperature range of 30 to 380° C. －７ ~50 x 10 －７ / ° C. Here, the "average thermal expansion coefficient in the temperature range of 30 to 380° C." can be measured with a dilatometer.

[0020] The glass of the present invention has a liquidus viscosity of 10 ４．５ The viscosity is preferably dPa·s or more. Here, the "liquidus viscosity" refers to the viscosity of glass at the liquidus temperature, and can be measured by the platinum sphere pull-up method.

[0021] The glass of the present invention is preferably used in an organic EL device.

[0022] The glass of the present invention has a glass composition containing, in mass %, SiO ２ 50-70%, Al ２ O ３ 15-25%, B ２ O ３ 1-5% Li ２ O + Na ２ O+K ２It is preferable that the composition contains 0 to 0.5% of O, 0 to 5% of MgO, 0 to 10% of CaO, 0 to 10% of SrO, and 0 to 10% of BaO. It is also preferable that the composition contains 15 to 30% of MgO, CaO, SrO, and BaO, with a mass % ratio of MgO / CaO being 0.68 or more. Furthermore, it is preferable that the composition contains SiO. ２ 57-62.5%, Al ２ O ３ 17-19.5%, B ２ O ３ It is preferable that the alloy contains 1.1 to 2.8% of As, 2 to 5% of MgO, 3.7 to 6% of CaO, 0 to 4.5% of SrO, 0 to 8% of BaO, and 17.51 ​​to 25% of MgO+CaO+SrO+BaO. ２ O ３ , Sb ２ O ３ It is more preferable that the composition does not contain any of the following. The reasons for limiting the content of each component as described above are as follows. In the explanation of the content of each component, % indicates % by mass unless otherwise specified.

[0023] SiO ２ is a component that forms the skeleton of glass. ２ If the content of SiO is too low, the thermal expansion coefficient becomes high and the density increases. ２ The lower limit of the amount of SiO is 50%, preferably 54%, more preferably 56%, more preferably 57%, even more preferably 58.5%, even more preferably 59.0%, and most preferably 59.5%. ２ If the content is too high, the Young's modulus decreases, the viscosity at high temperatures increases, the amount of heat required for melting increases, the melting cost increases, and the SiO ２ There is a risk that defects will occur due to undissolved raw materials, which will cause a decrease in yield. In addition, devitrified crystals such as cristobalite will be more likely to precipitate, which will lead to a decrease in liquidus viscosity. Therefore, SiO ２ The upper limit of the amount is 70%, preferably 65%, more preferably 62.5%, more preferably 62.1%, even more preferably 61.7%, even more preferably 61.4%, and most preferably 61.2%.

[0024] Al ２ O ３is a component that forms the skeleton of the glass, increases the Young's modulus, and also increases the strain point. ２ O ３ If the content of Al is too small, the Young's modulus is likely to decrease and the strain point is likely to decrease. ２ O ３ The lower limit of Al is 15%, preferably 16%, more preferably 17%, more preferably 17.3%, even more preferably 17.6%, and most preferably 17.9%. ２ O ３ If the content of Al is too high, devitrified crystals such as mullite tend to precipitate, and the liquidus viscosity tends to decrease. ２ O ３ The upper limit of the amount is 25%, preferably 22%, more preferably 19.5%, more preferably 18.8%, even more preferably 18.6%, and most preferably 18.5%.

[0025] In mass % ratio, SiO ２ / Al ２ O ３ is preferably 2.8 to 4.0, more preferably 3.0 to 3.9, even more preferably 3.2 to 3.6, and particularly preferably 3.3 to 3.5. ２ / Al ２ O ３ If SiO is too small, the strain point and / or devitrification resistance tend to decrease. ２ / Al ２ O ３ If the value is too large, the Young's modulus and / or melting property tend to decrease. ２ / Al ２ O ３ " is SiO ２ The mass% content of Al ２ O ３ This refers to the value obtained by dividing by the mass% content of the material.

[0026] B ２ O ３ is a component that enhances melting property and devitrification resistance. ２ O ３ If the content of B is too small, the melting property and the resistance to devitrification tend to decrease. ２ O ３The lower limit of B is 1%, preferably 1.1%, more preferably 1.3%, more preferably 1.5%, even more preferably 1.6%, and most preferably 1.7%. ２ O ３ If the content of B is too high, the Young's modulus and strain point tend to decrease. ２ O ３ The upper limit of the amount of is 5%, preferably 3.5%, more preferably 2.8%, more preferably 2.3%, even more preferably 2.1%, and most preferably 2.0%.

[0027] In mass % ratio, Al ２ O ３ / B ２ O ３ is preferably 4 to 19, more preferably 6 to 12, even more preferably 10.5 to 7, and particularly preferably 8.5 to 10.0. ２ O ３ / B ２ O ３ If is too small, the Young's modulus is likely to decrease. ２ O ３ / B ２ O ３ If "Al" is too large, the resistance to devitrification is likely to decrease. ２ O ３ / B ２ O ３ " is Al ２ O ３ The mass% content of B ２ O ３ This refers to the value obtained by dividing by the mass% content of the material.

[0028] Li ２ O + Na ２ O+K ２ O(Li ２ O, Na ２ O and K ２ The total mass % content of Li and O is 0 to 0.5%, preferably 0 to 0.2%, and more preferably 0 to 0.15%. ２ O, Na ２ O.K. ２ The individual content of O is preferably 0 to 0.5%, more preferably 0 to 0.1%, further preferably 0 to 0.05%, and most preferably 0 to 0.03%. ２O, Na ２ O and K ２ If the total amount of O is too large, there is a risk that alkali ions will diffuse into the semiconductor material formed in the heat treatment step.

[0029] Among alkaline earth metal oxides, MgO is a component that significantly increases Young's modulus. If the MgO content is too low, the melting property and Young's modulus tend to decrease. Therefore, the lower limit of MgO content is 0%, preferably 1.5%, more preferably 2%, more preferably 2.5%, even more preferably 3%, even more preferably 3.5%, even more preferably 3.8%, and most preferably 4.1%. On the other hand, if the MgO content is too high, devitrified crystals such as mullite tend to precipitate, and the liquidus viscosity tends to decrease. Therefore, the upper limit of MgO content is 5%, preferably less than 5%, more preferably 4.8%, more preferably less than 4.8%, even more preferably 4.7%, and most preferably less than 4.7%.

[0030] In mass % ratio, (Al ２ O ３ + MgO) / B ２ O ３ is preferably 4 to 23, more preferably 5 to 12, even more preferably 6 to 11, and particularly preferably 7.5 to 10.5. (Al ２ O ３ + MgO) / B ２ O ３ If is too small, the Young's modulus is likely to decrease. ２ O ３ + MgO) / B ２ O ３ If "(Al)" is too large, the resistance to devitrification is likely to decrease. ２ O ３ + MgO) / B ２ O ３ " is Al ２ O ３ The total mass% content of MgO is B ２ O ３ This refers to the value obtained by dividing by the mass% content of the material.

[0031] CaO is a component that reduces high-temperature viscosity and significantly improves meltability without lowering the strain point. It also increases Young's modulus. If the CaO content is too low, meltability tends to decrease. Therefore, the lower limit of CaO is 0%, preferably 1.5%, more preferably 3%, more preferably 3.7%, even more preferably 4.3%, even more preferably 4.5%, and most preferably 4.7%. On the other hand, if the CaO content is too high, the thermal expansion coefficient may become unduly high. Therefore, the upper limit of CaO is 10%, preferably 8%, more preferably 7%, more preferably 6%, even more preferably 5.7%, and most preferably 5.4%.

[0032] In terms of mass percent, the lower limit of the MgO / CaO content is preferably 0.18, more preferably 0.50, even more preferably 0.60, even more preferably 0.68, even more preferably 0.74, even more preferably 0.75, and most preferably 0.77. This makes it possible to effectively reduce the high-temperature viscosity while improving the Young's modulus of the glass. On the other hand, if this ratio is too large, the composition balance will be disrupted, making mullite and cordierite crystals more likely to precipitate, which may hinder mass production of the glass. Therefore, the upper limit of the MgO / CaO content is preferably 1.9, more preferably 1.4, even more preferably 1.3, more preferably 1.2, even more preferably 1.15, even more preferably 1.1, and most preferably 1.05.

[0033] SrO is a component that improves devitrification resistance and also reduces high-temperature viscosity and improves meltability without lowering the strain point. It also suppresses a decrease in liquidus viscosity. If the SrO content is too low, it becomes difficult to achieve the above-mentioned effects. Therefore, the lower limit of SrO is 0%, preferably 0.3%, more preferably 0.7%, more preferably 1.0%, even more preferably 1.3%, even more preferably 1.5%, even more preferably 1.7%, and most preferably 2.0%. On the other hand, if the SrO content is too high, the thermal expansion coefficient and density tend to increase. Therefore, the upper limit of SrO is 5%, preferably 4.5%, more preferably 4%, more preferably 3.5%, and most preferably 3.0%.

[0034] BaO is a component that improves devitrification resistance. If the BaO content is too low, it becomes difficult to obtain the above-mentioned effects. Therefore, the lower limit of BaO content is 0%, preferably 0.2%, more preferably 0.5%, more preferably 1%, more preferably 1.3%, and most preferably 1.5%. On the other hand, if the BaO content is too high, the Young's modulus tends to decrease and the thermal expansion coefficient and density tend to increase. Therefore, the upper limit of BaO content is preferably 10%, more preferably 9%, more preferably 8%, even more preferably 7%, and most preferably 6.5%.

[0035] If the total amount of MgO, CaO, SrO, and BaO is too small, the melting property tends to decrease. Therefore, the lower limit of the total amount of MgO, CaO, SrO, and BaO (RO) is preferably 12%, more preferably 15%, even more preferably 16.5%, more preferably 17.5%, even more preferably 18.2%, and most preferably 18.5%. On the other hand, if the total amount of MgO, CaO, SrO, and BaO is too large, the thermal expansion coefficient and density tend to increase. Therefore, the upper limit of the total amount of MgO, CaO, SrO, and BaO is preferably 30%, more preferably 25%, more preferably 22%, even more preferably 20%, and most preferably 19%.

[0036] Alkaline earth metal oxides (RO) are very important components for increasing the strain point, devitrification resistance, and melting property. If the amount of alkaline earth metal oxides is small, the strain point will rise, but if the amount of Al is small, the strain point will rise. ２ O ３ Therefore, the total amount of alkaline earth metal oxides (MgO + CaO + SrO + BaO) and Al ２ O ３ The ratio of the contents of MgO, CaO, SrO, and BaO is very important. Specifically, the ratio by mass is (MgO + CaO + SrO + BaO) / Al. ２ O ３ When this value is large, the melting property and formability are improved, but the strain point tends to decrease, and conversely, when this value is small, the strain point tends to increase, but the melting property and formability tend to decrease. ２ O ３The preferred lower limit of (MgO+CaO+SrO+BaO) / Al is preferably 0.60, more preferably 0.70, even more preferably 0.80, more preferably 0.85, and even more preferably 0.90. ２ O ３ The upper limit of the amount is preferably 1.70 or less, more preferably 1.50, more preferably 1.40, even more preferably 1.30, and still more preferably 1.20.

[0037] If the total amount of SrO and BaO is too small, devitrification resistance and melting property tend to decrease. Therefore, the lower limit of the total amount of SrO and BaO is preferably 0%, more preferably 4.0%, more preferably 5.0%, even more preferably 5.5%, and most preferably 6.5%. On the other hand, if the total amount of SrO and BaO is too large, the Young's modulus tends to decrease and the thermal expansion coefficient and density tend to increase. Therefore, the upper limit of the total amount of SrO and BaO is preferably 12.5%, more preferably 11.0%, more preferably 10.5%, even more preferably 10.0%, even more preferably 9.8%, and most preferably 9.5%.

[0038] The lower limit of (CaO-MgO)-(SrO-BaO) is preferably -2.0%, more preferably -1.0%, more preferably 0%, even more preferably 1.0%, even more preferably 2.0%, and most preferably 2.5%. This makes it possible to improve devitrification resistance and facilitate the design of highly productive glass. On the other hand, if (CaO-MgO)-(SrO-BaO) becomes too large, the Young's modulus decreases and the density increases. Therefore, the upper limit is preferably 12%, more preferably 11%, more preferably 10%, even more preferably 9%, even more preferably 8%, and most preferably 7%. Here, "(CaO-MgO)-(SrO-BaO)" is the mass% content obtained by subtracting the mass% content of BaO from the mass% content of SrO, from the mass% content of MgO subtracted from the mass% content of CaO.

[0039] In terms of mass %, (MgO + CaO) / (SrO + BaO) is preferably 0.5 to 3, more preferably 0.68 to 2.5, and particularly preferably 0.9 to 2.0. If (MgO + CaO) / (SrO + BaO) is too small, the Young's modulus is likely to decrease. On the other hand, if (MgO + CaO) / (SrO + BaO) is too large, the devitrification resistance is likely to decrease. Note that "(MgO + CaO) / (SrO + BaO)" refers to the value obtained by dividing the total mass % content of MgO and CaO by the total mass % content of SrO and BaO.

[0040] In addition to the above components, the following components may be added as optional components. Note that, from the viewpoint of accurately enjoying the effects of the present invention, the content of components other than the above components is preferably 10% or less in total, and particularly preferably 5% or less.

[0041] ZnO is a component that improves meltability. However, if a large amount of ZnO is contained, the glass is likely to devitrify and the strain point is likely to decrease. The ZnO content is preferably 0 to 5%, more preferably 0 to 3%, even more preferably 0 to 2%, and particularly preferably 0 to less than 1%.

[0042] TiO ２ is a component that reduces high-temperature viscosity and increases melting property, and also suppresses solarization. ２ If a large amount of TiO is contained, the glass becomes colored and the transmittance tends to decrease. ２ The content is preferably 0 to 2.5%, more preferably 0.0005 to 1%, even more preferably 0.001 to 0.5%, and particularly preferably 0.005 to 0.1%.

[0043] Y ２ O ３ , Nb ２ O ５ , La ２ O ３ Y has the effect of increasing the strain point, Young's modulus, etc. The total amount and individual contents of these components are preferably 0 to 5%, more preferably 0 to 1%, and particularly preferably 0 to 0.5%. ２ O ３ , Nb ２ O ５ , La ２ O３ If the total amount or the individual contents of are too high, the density and raw material costs tend to increase.

[0044] SnO ２ is a component that has a good fining effect in the high temperature range, and also a component that increases the strain point and reduces the high-temperature viscosity. ２ The content of SnO is preferably 0 to 1%, 0.001 to 1%, more preferably 0.01 to 0.5%, and particularly preferably 0.05 to 0.3%. ２ If the content is too high, SnO ２ Devitrification crystals of SnO are likely to precipitate. ２ If the content is less than 0.001%, it becomes difficult to obtain the above effects.

[0045] As mentioned above, SnO ２ is suitable as a fining agent, but F, SO are not suitable as a fining agent as long as the glass properties are not impaired. ３ , C, or metal powders such as Al and Si can be added in amounts up to 5% (preferably up to 1%, particularly preferably up to 0.5%). ２ etc. can also be added up to 5% (preferably up to 1%, particularly preferably up to 0.5%).

[0046] As a fining agent, As ２ O ３ , Sb ２ O ３ However, from an environmental viewpoint, it is preferable that the glass of the present invention contains substantially no of these components, that is, less than 0.05% of these components. ２ O ３ When it is contained, the solarization resistance tends to decrease.

[0047] Cl is a component that promotes the initial melting of a glass batch. Furthermore, adding Cl can promote the action of a fining agent. As a result, melting costs can be reduced while the life of a glass manufacturing furnace can be extended. However, if the Cl content is too high, the strain point tends to decrease. Therefore, the Cl content is preferably 0 to 3%, more preferably 0.0005 to 1%, and particularly preferably 0.001 to 0.5%. As a source for introducing Cl, a chloride of an alkaline earth metal oxide such as strontium chloride, or a source such as aluminum chloride can be used.

[0048] Fe ２ O ３ is a component that is mixed in as a raw material impurity and reduces the electrical resistivity. ２ O ３ The content of Fe is preferably 0 to 300 ppm by mass, more preferably 80 to 250 ppm by mass, and particularly preferably 100 to 200 ppm by mass. ２ O ３ If the content is too low, the raw material cost tends to rise. ２ O ３ If the content is too large, the electrical resistivity of the molten glass increases, making it difficult to carry out electric melting.

[0049] The glass of the present invention preferably has the following properties:

[0050] The average thermal expansion coefficient in the temperature range of 30 to 380°C is preferably 30 x 10 －７ ~50 x 10 －７ / °C, more preferably 32 x 10 －７ ~48 x 10 －７ / °C, more preferably 33 x 10 －７ ~45 x 10 －７ / °C, more preferably 34 x 10 －７ ~44 x 10 －７ / °C, particularly preferably 35 x 10 －７ ~44 x 10 －７ / ° C. This makes it easier to reduce pattern misalignment during TFT fabrication.

[0051] The Young's modulus is preferably 78 GPa or more, more preferably greater than 78 GPa, still more preferably greater than 80 GPa, and particularly preferably from 81 to 90 GPa. If the Young's modulus is too low, defects caused by bending of the glass plate are likely to occur.

[0052] The strain point is preferably 680° C. or higher, more preferably higher than 680° C., still more preferably 690° C. or higher, and particularly preferably 700 to 900° C. In this way, thermal shrinkage of the glass sheet can be suppressed in the LTPS process.

[0053] The liquidus temperature is preferably 1450°C or lower, more preferably less than 1210°C, even more preferably 1200°C or lower, and particularly preferably 1190°C or lower. This makes it easier to prevent devitrification crystals from occurring during glass production, which can reduce productivity. Furthermore, since the glass is easier to form using the overflow downdraw method, it is easier to improve the surface quality of the glass sheet and reduce the manufacturing cost of the glass sheet. The liquidus temperature is an index of devitrification resistance, and the lower the liquidus temperature, the better the devitrification resistance.

[0054] The liquidus viscosity is preferably 10 ４．１８ dPa·s or more, more preferably 10 ４．３ dPa·s or more, more preferably 10 ４．５ dPa·s or more, more preferably 10 ５．０ dPa·s or more, more preferably 10 ５．２ dPa·s or more, particularly preferably 10 ５．３

[0033] In this way, devitrification is less likely to occur during forming, and thus forming by the overflow downdraw method becomes easier, thereby making it possible to improve the surface quality of the glass sheet and reduce the manufacturing cost of the glass sheet. The liquidus viscosity is an index of devitrification resistance and formability, and the higher the liquidus viscosity, the more improved the devitrification resistance and formability.

[0055] High temperature viscosity 10 ２．５ The temperature at viscosity dPa·s is preferably 1650°C or less, more preferably 1600°C or less, even more preferably 1580°C or less, and particularly preferably 1560°C or less.２．５ If the temperature at high viscosity 10 dPa·s is too high, it becomes difficult to melt the glass batch, and the manufacturing cost of the glass plate increases. ２．５ The temperature at dPa·s corresponds to the melting temperature, and the lower this temperature is, the better the melting property is.

[0056] β-OH is an index indicating the amount of water in glass, and reducing β-OH can increase the strain point. Furthermore, even when the glass composition is the same, a smaller β-OH results in a smaller thermal shrinkage at temperatures below the strain point. β-OH is preferably 0.30 / mm or less, more preferably 0.25 / mm or less, more preferably 0.20 / mm or less, even more preferably 0.15 / mm or less, and particularly preferably 0.10 / mm or less. If β-OH is too small, meltability tends to decrease. Therefore, β-OH is preferably 0.01 / mm or more, particularly 0.03 / mm or more.

[0057] The following methods can be used to reduce β-OH: (1) Select raw materials with low water content. (2) Add components (Cl, SO) that reduce β-OH in the glass. ３ (3) To reduce the amount of moisture in the furnace atmosphere. (4) To reduce the amount of N in the molten glass. ２ (5) Use a small melting furnace. (6) Increase the flow rate of molten glass. (7) Use an electric melting method.

[0058] Here, "β-OH" refers to a value obtained by measuring the transmittance of glass using FT-IR and using the following mathematical formula 1.

[0059] [Math. 1] β-OH=(1 / X)log(T １ / T ２ ) X: Plate thickness (mm) T １ :Reference wavelength 3846cm －１ Transmittance (%) at T ２ : Hydroxyl group absorption wavelength 3600 cm －１ Minimum transmittance (%) in the vicinity

[0060] The glass of the present invention is preferably in the form of a sheet and formed by the overflow downdraw method. The overflow downdraw method is a method for producing a glass sheet by overflowing molten glass from both sides of a heat-resistant trough-shaped structure, and drawing the overflowed molten glass downward while joining at the lower end of the trough-shaped structure. In the overflow downdraw method, the surface that will become the surface of the glass sheet does not contact the trough-shaped refractory and is formed in a free surface state. Therefore, an unpolished glass sheet with good surface quality can be produced inexpensively, and thinning is easy.

[0061] In addition to the overflow downdraw method, it is also possible to form a glass sheet by, for example, a downdraw method (such as a slot-down method) or a float method.

[0062] When the glass is in a plate shape, the thickness is not particularly limited, but is preferably less than 0.7 mm, more preferably 0.6 mm or less, even more preferably 0.5 mm or less, and particularly preferably 0.4 mm or less. The thinner the plate thickness, the more lightweight the organic EL device can be. The plate thickness can be adjusted by the flow rate, plate drawing speed, etc. during glass production.

[0063] The glass of the present invention is preferably used for organic EL devices, particularly organic EL televisions. In the use of organic EL televisions, a plurality of devices are fabricated on a glass plate, which is then cut into individual devices to reduce costs (so-called multi-panel cutting). The glass of the present invention has a low liquidus temperature and a high liquidus viscosity, making it easy to form large glass plates, and can accurately meet such requirements.

[0064] The present invention will be described below based on examples. Note that the following examples are merely illustrative and the present invention is not limited to the following examples.

[0065] Tables 1 to 29 show examples of the present invention (samples Nos. 1 to 283).

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[0093]

[0094]

[0095] First, a glass batch prepared by blending glass raw materials to obtain the glass composition shown in the table was placed in a platinum crucible and melted at 1600 to 1650°C for 24 hours. When melting the glass batch, the mixture was stirred using a platinum stirrer to homogenize it. Next, the molten glass was poured onto a carbon plate, formed into a plate shape, and then slowly cooled at a temperature near the annealing point for 30 minutes. For each of the obtained samples, the average coefficient of thermal expansion CTE, density ρ, strain point Ps, annealing point Ta, softening point Ts, and high-temperature viscosity 10 in the temperature range of 30 to 380°C were measured. ４．５ Temperature at dPa·s, high temperature viscosity 10 ４．０ Temperature at dPa·s, high temperature viscosity 10 ３ Temperature at dPa·s, high temperature viscosity 10 ２．５ Temperature in dPa s, liquidus temperature TL, and viscosity log at liquidus temperature TL １０ The ηTL and Young's modulus E were evaluated.

[0096] The average coefficient of thermal expansion CTE in the temperature range of 30 to 380° C. is a value measured with a dilatometer.

[0097] The density ρ is a value measured by the well-known Archimedes method.

[0098] The strain point Ps, annealing point Ta, and softening point Ts are values ​​measured based on the methods of ASTM C336 and C338.

[0099] High temperature viscosity 10 ４．５ dPa·s, 10 ４ dPa·s, 10 ３ dPa·s, 10 ２．５ The temperature at dPa·s is a value measured by the platinum sphere pull-up method.

[0100] The liquidus temperature TL is the temperature at which crystals precipitate when a glass powder that passes through a standard 30 mesh (500 μm) sieve and remains on a 50 mesh (300 μm) sieve is placed in a platinum boat and held in a temperature gradient furnace for 24 hours.

[0101] liquidus viscosity log １０ ηTL is the viscosity of the glass at the liquidus temperature TL measured by the platinum ball pull-up method.

[0102] The Young's modulus E is a value measured by a well-known resonance method. The specific Young's modulus E / ρ is a value obtained by dividing the Young's modulus E by the density ρ.

[0103] As is clear from Tables 1 to 29, Samples No. 1 to 283 have glass compositions regulated within a predetermined range, and have Young's modulus of 80.3 GPa or more and strain points of 707°C or more. ２．５ The temperature at dpa·s is 1609°C or less, the liquidus temperature is 1285°C or less, and the liquidus viscosity is 10 ４．１８ Since the viscosity is dPa s or more, productivity is good, thermal shrinkage in the LTPS process can be reduced, and defects due to bending are unlikely to occur even when the film is made larger and thinner. Therefore, Samples No. 1 to 283 are suitable for use as substrates for organic EL devices.

[0104] The glass of the present invention is suitable as a substrate for organic EL devices, particularly organic EL televisions, and is also suitable as a substrate for flat panel displays such as liquid crystal displays, cover glass for image sensors such as charge-coupled devices (CCDs) and life-size proximity solid-state image sensors (CISs), substrates and cover glass for solar cells, substrates for organic EL lighting, etc.

Claims

1. The glass composition, by mass%, is SiO ２ 50-70%, Al ２ O ３ 15-25%, B ２ O ３ 1-5%, Li ２ O+Na ２ O+K ２ A glass comprising 0-0.5% O, 0-5% MgO, 0-10% CaO, 0-5% SrO, and 0-10% BaO.

2. The glass composition, by mass%, is SiO ２ 57-62.5%, Al ２ O ３ 17-19.5%, B ２ O ３ 2. The glass according to claim 1, comprising 1.1-2.8% MgO, 2-5% MgO, 3.7-6% CaO, 0-4.5% SrO, 0-8% BaO, and 17.5% or more of MgO+CaO+SrO+BaO, with a mass percentage ratio of MgO / CaO being 0.68 or more.

3. Mass % ratio (MgO+CaO+SrO+BaO) / Al ２ O ３ 3. The glass according to claim 1, wherein the refractive index is 0.70 to 1.

70.

4. The glass according to claim 1 or 2, characterized in that it has a Young's modulus of 78 GPa or more, a strain point of 680°C or more, and a liquidus temperature of 1450°C or less.

5. Furthermore, SnO ２ 3. The glass according to claim 1, further comprising 0.001 to 1 mass % of 6. The glass according to claim 1 or 2, characterized in that it has a strain point of 690°C or higher.

7. The glass according to claim 1 or 2, characterized in that the Young's modulus is higher than 80 GPa.

8. The average thermal expansion coefficient in the temperature range of 30 to 380°C is 30 x 10 －７ ~50 x 10 －７ 3. The glass according to claim 1, wherein the temperature is 0.15 to 100° C.

9. Liquidus viscosity is 10 ４．５ 3. The glass according to claim 1, wherein the viscosity is ≥ 100 dPa·s.

10. The glass according to claim 1 or 2, which is used in an organic EL device.

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