Alkali-free glass plate

Abstract

Provided is an inexpensive alkali-free glass plate having excellent productivity and a sufficiently high strain point and Young's modulus.　The alkali-free glass plate is characterized by having a glass composition, in mol%, of 65 to 73% SiO2, 10 to 15% Al2O3, 0 to 5% B2O3, 0 to 0.5% Li2O+Na2O+K2O, 0.1 to 8% MgO, 0 to 10% CaO, 0 to 6% SrO, 0 to 5% BaO, 8 to 25% MgO+CaO+SrO+BaO, 0.0001 to 10% Y2O3, with the mol% ratio of (MgO+CaO+SrO+BaO) / Al2O3 being 0.5 to 2, the mol% ratio of (CaO+SrO) / Y2O3 being 0.1 to 12, the mol% ratio of SiO2 / (MgO+CaO+SrO+BaO) being 2.8 to 9, and the mol% ratio of (B2O3+BaO) / MgO being 0 to 2.

Description

Alkali-free glass plate

[0001] This invention relates to alkali-free glass plates, and more particularly to alkali-free glass plates suitable for organic EL displays and magnetic recording media.

[0002] Electronic devices such as organic EL displays are thin, offer excellent video display capabilities, and consume low power, making them suitable for applications such as flexible devices and mobile phone displays.

[0003] Glass plates are widely used as substrates for organic EL displays. Glass plates for this application are mainly required to have the following characteristics: (1) To prevent the diffusion of alkali ions into the semiconductor material formed during the heat treatment process, they should contain almost no alkali metal oxides, i.e., alkali-free glass (glass with an alkali metal oxide content of 0.5 mol% or less in the glass composition); (2) To reduce the cost of the glass plates, they should be formed by the overflow down-draw method, which makes it easy to improve surface quality, and should have excellent productivity, especially excellent meltability and devitrification resistance; (3) To reduce thermal shrinkage of the glass plate in the LTPS (low temperature poly silicon) process and oxide TFT process, they should have a high strain point.

[0004] Furthermore, magnetic recording media such as magnetic disks and optical disks are used in various information devices.

[0005] Glass plates are widely used as substrates for magnetic recording media, replacing conventional aluminum alloy substrates. In recent years, to meet the need for even higher recording density, magnetic recording media using energy-assisted magnetic recording methods, i.e., energy-assisted magnetic recording media, have been investigated. Energy-assisted magnetic recording media also use glass plates, and a magnetic layer or the like is deposited on the surface of the glass plate. In energy-assisted magnetic recording media, ordered alloys with a large magnetic anisotropy coefficient Ku (hereinafter referred to as "high Ku") are used as the magnetic material for the magnetic layer.

[0006] Japanese Patent Publication No. 2012-106919 Japanese Patent Publication No. 2021-086643

[0007] Incidentally, OLED devices are also widely used in OLED televisions. There is a strong demand for larger and thinner OLED televisions, and the demand for high-resolution displays such as 8K is also increasing. Therefore, glass plates for these applications need to be large and thin, yet possess thermal dimensional stability that can withstand the demands of high resolution. Furthermore, in order to reduce the price difference between OLED televisions and LCD displays, cost reduction is required, and similarly, low cost is required for the glass plates. However, when glass plates are made larger and thinner, they become more prone to bending, which drives up manufacturing costs.

[0008] Glass sheets formed by glass manufacturers undergo processes such as cutting, annealing, inspection, and cleaning. During these processes, the glass sheets are loaded and unloaded into cassettes with multiple shelves. These cassettes are typically designed to hold the glass sheets horizontally by resting their opposing edges on shelves formed on the left and right inner surfaces. However, large, thin glass sheets have a large amount of deflection, which can cause damage when loading them into the cassette due to contact with the cassette, or make them unstable and prone to excessive shaking when unloading. Since cassettes of this type are also used by electronic device manufacturers, similar problems occur. To solve this problem, increasing the Young's modulus of the glass sheet to reduce deflection is an effective solution.

[0009] Furthermore, as mentioned above, in LTPS and oxide TFT processes for obtaining high-resolution displays, it is necessary to increase the strain point of the glass plate in order to reduce the thermal shrinkage of the large glass plate.

[0010] However, attempting to increase the Young's modulus and strain point of a glass plate disrupts the balance of the glass composition, leading to decreased productivity, particularly a significant decline in devitrification resistance and an increase in liquid-phase viscosity, making it impossible to mold using the overflow down-draw method. Furthermore, decreased meltability and higher glass molding temperatures tend to shorten the lifespan of the molded product. As a result, the cost of raw glass plates skyrockets.

[0011] Furthermore, glass plates for magnetic recording media are required to have high rigidity (in other words, a high Young's modulus) to prevent significant deformation during high-speed rotation. In detail, in a disk-shaped magnetic recording medium, information is written and read along the direction of rotation while the magnetic head moves radially and the medium rotates at high speed around a central axis. In recent years, the rotation speed to increase the writing and reading speed has been increasing from 5400 rpm to 7200 rpm, and even to 10000 rpm. However, in disk-shaped magnetic recording media, positions for recording information are assigned in advance according to the distance from the central axis. Therefore, if the glass plate deforms during rotation, the magnetic head will shift position, making accurate reading difficult.

[0012] In recent years, the Dynamic Flying Height (DFH) mechanism has been incorporated into magnetic heads to significantly reduce the gap between the recording / playback element of the magnetic head and the surface of the magnetic recording medium (i.e., reduce the amount of levitation), thereby achieving even higher recording densities. The DFH mechanism is a mechanism that provides a heating element, such as a tiny heater, near the recording / playback element of the magnetic head, causing thermal expansion only around the element towards the surface of the medium. By incorporating such a mechanism, the distance between the magnetic head and the magnetic layer of the medium is reduced, making it possible to pick up signals from smaller magnetic particles and achieve higher recording densities. On the other hand, because the gap between the recording / playback element of the magnetic head and the surface of the magnetic recording medium becomes extremely small, for example, less than 2 nm, there is a risk that the magnetic head may collide with the surface of the magnetic recording medium even with a slight impact. This tendency becomes more pronounced at higher rotation speeds. Therefore, at high rotation speeds, it is important to prevent the bending and fluttering (i.e., fluttering) of the glass plate that can cause this collision.

[0013] Furthermore, in order to increase the degree of regularization (i.e., regularity) of the magnetic layer and achieve a higher Ku value, the substrate including the glass plate may be heat-treated at a high temperature of about 800 °C during or before and after the formation of the magnetic layer. Since this heat treatment temperature needs to be increased as the recording density increases, higher heat resistance than that of conventional glass plates for magnetic recording media, that is, a higher distortion point, is required. In addition, after the formation of the magnetic layer, laser irradiation may be performed on the substrate including the glass plate. Such heat treatment and laser irradiation also aim to increase the annealing temperature and coercive force of the magnetic layer including an FePt-based alloy or the like.

[0014] However, as described above, when attempting to increase the Young's modulus and distortion point of the glass plate, the balance of the glass composition is disrupted, productivity decreases, particularly the devitrification resistance significantly decreases, and the liquid-phase viscosity increases, making it impossible to form by the overflow down-draw method. In addition, the melting property deteriorates, the forming temperature of the glass becomes higher, and the life of the formed body tends to be shortened. As a result, the raw material cost of the glass plate soars.

[0015] Therefore, the present invention was conceived in view of the above circumstances, and its technical problem is to provide an alkali-free glass plate that is excellent in productivity and has a sufficiently high distortion point and Young's modulus at a low cost.

[0016] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by an alkali-free glass plate satisfying a predetermined composition.

[0017] (1) The alkali-free glass plate of the present invention has, as a glass composition, in mol%, SiO ２ 65 to 73%, Al ２ O ３ 10 to 15%, B ２ O ３ 0 to 5%, Li ２ O + Na ２ O + K ２ O 0 to 0.5%, MgO 0.1 to 8%, CaO 0 to 10%, SrO 0 to 6%, BaO 0 to 5%, MgO + CaO + SrO + BaO 8 to 25%, Y ２ O ３ containing 0.0001 to 10%, and the mol% ratio (MgO + CaO + SrO + BaO) / Al２ O ３ 0.5-2, mol% ratio (CaO+SrO) / Y ２ O ３ 0.1-12, mol% ratio SiO ２ / (MgO+CaO+SrO+BaO) 2.8-9, mol% ratio (B ２ O ３ It is characterized by being +BaO) / MgO 0 to 2. Here, "Li ２ O + Na ２ O+K ２ "O" is Li ２ O, Na ２ O and K ２ This refers to the total amount of oxygen. "MgO + CaO + SrO + BaO" refers to the total amount of MgO, CaO, SrO, and BaO. "(MgO + CaO + SrO + BaO) / Al ２ O ３ " is the total amount of MgO, CaO, SrO, and BaO in Al ２ O ３ This is the value obtained by dividing by the mol% content. (CaO + SrO) / Y ２ O ３ " is the total amount of CaO and SrO Y ２ O ３ This is the value obtained by dividing by the mol% content. ２ / (MgO+CaO+SrO+BaO) is SiO ２ This is the value obtained by dividing the mol% content by the total amount of MgO, CaO, SrO, and BaO. (B ２ O ３ "+BaO) / MgO" is B ２ O ３ This is the value obtained by dividing the total amount of BaO by the mol% content of MgO. Note that "alkali-free glass" as used in this invention refers to Li ２ O + Na ２ O+K ２ This refers to glass with an oxygen content of 0.5 mol% or less.

[0018] (2) The alkali-free glass plate of the present invention, in the configuration of (1) above, has a glass composition of SiO in mol%. ２ 65-73%, Al ２ O ３ 10-15%, B ２O ３ 0-2%, Li ２ O + Na ２ O+K ２ O 0-0.5%, MgO 1-8%, CaO 0-10%, SrO 0-6%, BaO 0-5%, MgO+CaO+SrO+BaO 8-25%, Y ２ O ３ It contains 0.1-5% of the substance, in mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ 0.8 to 1.5, mol% ratio (CaO+SrO) / Y ２ O ３ 1 to 10, mol% ratio SiO ２ / (MgO+CaO+SrO+BaO) 3-6, mol% ratio (B ２ O ３ The ratio of (BaO) / MgO is preferably 0 to 0.9.

[0019] (3) The alkali-free glass plate of the present invention, in any of the configurations of (1) to (2) above, has a glass composition of mol% SnO ２ It is preferable that it contains 0.001 to 1%.

[0020] (4) The alkali-free glass plate of the present invention, in any of the configurations (1) to (3) above, has a glass composition of As ２ O ３ and Sb ２ O ３ It is preferable that it substantially does not contain As. ２ O ３ and Sb ２ O ３ "Substantially does not contain As ２ O ３ and Sb ２ O ３ This refers to cases where the content of each substance is 0.05 mol% or less.

[0021] (5) The alkali-free glass plate of the present invention, in any of the configurations (1) to (4) above, has an average thermal expansion coefficient of 28 × 10 in the temperature range of 30 to 380°C. －７ ~60 x 10 －７It is preferable that the coefficient of thermal expansion is / °C. Here, the "average thermal expansion coefficient in the temperature range of 30 to 380°C" can be measured with a dilatometer.

[0022] (6) In any of the configurations (1) to (5) above, the alkali-free glass plate of the present invention preferably has a Young's modulus of 80 GPa or more. Here, "Young's modulus" refers to the value measured by the bending resonance method. Note that 1 GPa is approximately 101.9 kgf / mm ２ It corresponds to this.

[0023] (7) The alkali-free glass plate of the present invention has a specific Young's modulus of 29 GPa / g·cm in any of the configurations (1) to (6) above. ３ The above is preferable. Here, "specific Young's modulus" is the value obtained by dividing Young's modulus by density.

[0024] (8) In any of the configurations (1) to (7) above, the alkali-free glass plate of the present invention preferably has a strain point of 740°C or higher. Here, "strain point" refers to the value measured according to the ASTM C336 method.

[0025] (9) In any of the configurations (1) to (8) above, the alkali-free glass plate of the present invention preferably has an annealing point of 790°C or higher. Here, "annealing point" refers to a value measured according to the ASTM C336 method.

[0026] (10) In any of the above configurations (1) to (9), the alkali-free glass plate of the present invention preferably has a liquidus temperature of 1360°C or less. Here, "liquidus temperature" refers to the temperature at which crystals precipitate after the glass powder that has passed through a standard 30-mesh (500 μm) sieve and remained in a 50-mesh (300 μm) sieve is placed in a platinum boat and held in a temperature gradient furnace for 24 hours.

[0027] (11) The alkali-free glass plate of the present invention has a liquid phase viscosity of 10 in any of the configurations (1) to (10) above. ３．９ It is preferable that the viscosity is dPa·s or higher. Here, "liquid-phase viscosity" refers to the viscosity of the glass at the liquid-phase temperature and can be measured by the platinum ball pulling method.

[0028] (12) The alkali-free glass plate of the present invention preferably used in an organic EL device in any of the configurations (1) to (11) above.

[0029] (13) The alkali-free glass plate of the present invention preferably used in a magnetic recording medium in any of the configurations (1) to (12) above.

[0030] (14) The alkali-free glass plate of the present invention has, as a glass composition, in mol%, SiO ２ 65 to 73%, Al ２ O ３ 10 to 15%, B ２ O ３ 0 to 5%, Li ２ O + Na ２ O + K ２ O 0 to 0.5%, MgO 0.1 to 8%, CaO 0 to 10%, SrO 0 to 6%, BaO 0 to 5%, MgO + CaO + SrO + BaO 8 to 25%, Ln ２ O ３ containing 0.0001 to 10%, mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ 0.5 to 2, mol% ratio (CaO + SrO) / Ln ２ O ３ 0.1 to 12, mol% ratio SiO ２ / (MgO + CaO + SrO + BaO) 2.8 to 9, mol% ratio (B ２ O ３ + BaO) / MgO 0 to 2 is preferable. Here, "Ln ２ O ３ " means Sc ２ O ３ , Y ２ O ３ , La ２ O ３ , Nd ２ O ３ , Pm ２ O ３ , Sm ２ O ３ , Eu ２ O ３ , Gd ２ O ３ , Tb ２ O ３ , Dy２ O ３ Ho ２ O ３ Er ２ O ３ , Tm ２ O ３ Yb ２ O ３ Lu ２ O ３ This is the total amount of oxides containing one or more of the following: (CaO + SrO) / Ln ２ O ３ " is the total amount of CaO and SrO Ln ２ O ３ This is the value obtained by dividing by the mol% content.

[0031] According to the present invention, it is possible to provide alkali-free glass plates with excellent productivity and sufficiently high strain point and Young's modulus at a low cost.

[0032] The alkali-free glass plate of the present invention has a glass composition of mol% SiO ２ 65-73%, Al ２ O ３ 10-15%, B ２ O ３ 0-5%, Li ２ O + Na ２ O+K ２ O 0-0.5%, MgO 0.1-8%, CaO 0-10%, SrO 0-6%, BaO 0-5%, MgO+CaO+SrO+BaO 8-25%, Y ２ O ３ It contains 0.0001 to 10%, in mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ 0.5-2, mol% ratio (CaO+SrO) / Y ２ O ３ 0.1-12, mol% ratio SiO ２ / (MgO+CaO+SrO+BaO) 2.8-9, mol% ratio (B ２ O ３The compound is characterized by having a concentration of 0 to 2 (+BaO) / MgO. The reasons for limiting the content of each component as described above are explained below. In the explanation of the content of each component, percentages represent mol% unless otherwise specified. Unless otherwise specified, the lower limit indicates that the value is greater than or equal to that value, and the upper limit indicates that the value is less than or equal to that value.

[0033] SiO ２ SiO is a component that forms the framework of glass. ２ If the SiO content is too low, the density tends to increase, making the glass more prone to bending. Therefore, ２ The lower limit is preferably 65%, more preferably 65.2%, even more preferably 65.4%, even more preferably 65.6%, even more preferably 65.8%, even more preferably 66%, even more preferably 66.2%, even more preferably 66.4%, even more preferably 66.6%, even more preferably 66.8%, even more preferably 67%, even more preferably 67.2%, even more preferably 67.4%, even more preferably 67.6%, even more preferably 67.8%, even more preferably 68%, even more preferably 68.1%, even more preferably 68.2%, even more preferably 68.4%, even more preferably 68.6%, even more preferably 68.8%, even more preferably 69%, even more preferably 69.2%, even more preferably 69.4%, even more preferably 69.6%, even more preferably 69.8%, even more preferably 70%, even more preferably 70.2%, even more preferably 70.3%, even more preferably 70.4%, and most preferably 70.5%. ２ If the content is too high, the Young's modulus decreases, the high-temperature viscosity increases, the amount of heat required for melting increases, and the melting cost skyrockets. ２ Undissolved raw materials may form, potentially leading to a decrease in yield. Furthermore, devitrified crystals such as cristobalite may easily precipitate, leading to a decrease in liquid-phase viscosity. Therefore, SiO ２ The upper limit of the amount is preferably 73%, more preferably 72.8%, even more preferably 72.6%, even more preferably 72.4%, even more preferably 72.2%, even more preferably 72%, even more preferably 71.8%, even more preferably 71.6%, and most preferably 71.4%.

[0034] Al ２ O ３ Al is a component that forms the framework of glass, increases Young's modulus, and further increases the strain point. ２ O ３ If the content of Al is too low, the Young's modulus tends to decrease, and the strain point also tends to decrease. Therefore, Al ２ O ３ The lower limit of the amount is preferably 10%, more preferably 10.2%, even more preferably 10.4%, even more preferably 10.6%, even more preferably 10.8%, even more preferably 10.9%, even more preferably 11%, even more preferably 11.2%, even more preferably 11.4%, even more preferably 11.6%, even more preferably 11.8%, even more preferably 12%, even more preferably 12.2%, even more preferably 12.4%, even more preferably 12.6%, and most preferably 12.8%. On the other hand, Al ２ O ３ If the content is too high, devitrified crystals such as mullite tend to precipitate, and the liquid phase viscosity tends to decrease. Therefore, Al ２ O ３ The upper limit of the amount is preferably 15%, more preferably 14.8%, even more preferably 14.6%, even more preferably 14.4%, even more preferably 14.2%, even more preferably 14%, even more preferably 13.9%, even more preferably 13.8%, even more preferably 13.7%, even more preferably 13.5%, and most preferably 13.4%.

[0035] B ２ O ３ It has the effect of improving meltability and resistance to devitrification. Therefore, B ２ O ３ The lower limit is preferably 0%, more preferably greater than 0%, even more preferably 0.001%, even more preferably 0.01%, even more preferably 0.05%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.3%, even more preferably 0.4%, even more preferably 0.5%, even more preferably 0.6%, even more preferably 0.7%, even more preferably 0.8%, even more preferably 0.9%, and most preferably 1%. On the other hand, B ２ O ３If the content is too high, the Young's modulus and strain point tend to decrease. Therefore, B ２ O ３ The upper limit of the amount is preferably 5%, more preferably 4.8%, even more preferably 4.6%, even more preferably 4.4%, even more preferably 4.2%, even more preferably 4%, even more preferably 3.8%, even more preferably 3.6%, even more preferably 3.4%, even more preferably 3.2%, even more preferably 3%, even more preferably 2.8%, even more preferably 2.6%, even more preferably 2.4%, even more preferably 2.2%, even more preferably 2%, even more preferably 1.8%, and most preferably 1.6%.

[0036] Li ２ O, Na ２ O and K ２ O is a component that is inevitably mixed in from the glass raw material, and the lower limit of its total amount is preferably 0%, more preferably 0.001%, even more preferably 0.005%, even more preferably 0.008%, and most preferably 0.01%. On the other hand, Li ２ O, Na ２ O and K ２ The upper limit of O is preferably 0.5%, more preferably 0.1%, even more preferably 0.09%, even more preferably 0.08%, even more preferably 0.06%, and most preferably 0.05%. ２ O, Na ２ O and K ２ If the total amount of O is too high, there is a risk that alkali ions will diffuse into the semiconductor material formed during the heat treatment process. ２ O, Na ２ O and K ２ The upper and lower limits for the content of each component of O are as stated above.

[0037] MgO is a component that significantly increases Young's modulus among alkaline earth metal oxides. It is also a component that improves meltability. The lower limit of the amount of MgO is preferably 0%, more preferably greater than 0%, even more preferably 0.01%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.3%, even more preferably 0.5%, even more preferably 0.7%, even more preferably 0.9%, even more preferably 1%, even more preferably 1.2%, even more preferably 1.5%, and most preferably 2%. On the other hand, if the MgO content is too high, devitrified crystals such as mullite tend to precipitate, and the liquid phase viscosity tends to decrease. Therefore, the upper limit of MgO is preferably 8%, more preferably 7.8%, even more preferably 7.6%, even more preferably 7.4%, even more preferably 7.2%, even more preferably 7%, even more preferably 6.8%, even more preferably 6.6%, even more preferably 6.4%, even more preferably 6.2%, even more preferably 6%, even more preferably 5.8%, even more preferably 5.6%, and most preferably 5.5%.

[0038] CaO is a component that significantly increases meltability by lowering high-temperature viscosity without lowering the strain point. It is also a component that increases Young's modulus. If the CaO content is too low, meltability tends to decrease. Therefore, the lower limit of CaO is preferably 0%, more preferably 0.1%, even more preferably 0.2%, even more preferably 0.4%, even more preferably 0.5%, even more preferably 0.6%, even more preferably 0.8%, even more preferably 1%, even more preferably 1.2%, even more preferably 1.4%, even more preferably 1.6%, even more preferably 1.8%, even more preferably 2%, even more preferably 2.2%, even more preferably 2.4%, even more preferably 2.6%, and most preferably 2.8%. On the other hand, if the CaO content is too high, the coefficient of thermal expansion tends to increase. Therefore, the upper limit of CaO is preferably 10%, more preferably 9.8%, even more preferably 9.6%, even more preferably 9.4%, even more preferably 9.2%, even more preferably 9%, even more preferably 8.8%, even more preferably 8.6%, even more preferably 8.4%, even more preferably 8.2%, even more preferably 8%, even more preferably 7.8%, even more preferably 7.6%, even more preferably 7.4%, even more preferably 7.2%, and most preferably 7%.

[0039] SrO is a component that enhances devitrification resistance, lowers high-temperature viscosity without reducing the strain point, and improves meltability. It is also a component that suppresses the decrease in liquid phase viscosity. Therefore, the lower limit of SrO is preferably 0%, more preferably greater than 0%, even more preferably 0.01%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.3%, even more preferably 0.5%, even more preferably 0.7%, even more preferably 0.8%, even more preferably 1%, even more preferably 1.2%, even more preferably 1.4%, even more preferably 1.5%, even more preferably 1.7%, even more preferably 1.8%, and most preferably 2%. On the other hand, if the SrO content is too high, the coefficient of thermal expansion tends to increase. Therefore, the upper limit of SrO is preferably 6%, more preferably 5.8%, even more preferably 5.6%, even more preferably 5.4%, even more preferably 5.2%, even more preferably 5%, even more preferably 4.9%, even more preferably 4.8%, even more preferably 4.7%, and most preferably 4.5%.

[0040] BaO is a component that enhances resistance to devitrification. Therefore, the lower limit of BaO is preferably 0%, more preferably more than 0%, even more preferably 0.01%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.3%, even more preferably 0.5%, even more preferably 0.7%, even more preferably 0.8%, even more preferably 1%, even more preferably 1.2%, even more preferably 1.4%, even more preferably 1.5%, even more preferably 1.7%, even more preferably 1.8%, and most preferably 2%. On the other hand, if the BaO content is too high, the coefficient of thermal expansion tends to increase. Therefore, the upper limit of BaO is preferably 6%, more preferably 5.8%, even more preferably 5.6%, even more preferably 5.4%, even more preferably 5.2%, even more preferably 5%, even more preferably 4.9%, even more preferably 4.8%, even more preferably 4.7%, and most preferably 4.5%.

[0041] MgO, CaO, SrO, and BaO are components that enhance meltability. If the content of MgO + CaO + SrO + BaO is too low, meltability tends to decrease. Therefore, the lower limit of the amount of MgO + CaO + SrO + BaO is preferably 8%, more preferably 8.1%, even more preferably 8.2%, even more preferably 8.4%, even more preferably 8.6%, even more preferably 8.8%, even more preferably 9%, even more preferably 9.2%, even more preferably 9.4%, even more preferably 9.5%, even more preferably 9.6%, even more preferably 9.8%, even more preferably 10%, even more preferably 10.2%, and most preferably 10.5%. On the other hand, if the content of MgO + CaO + SrO + BaO is too high, the density increases, and the glass becomes more prone to bending. Therefore, the upper limit of MgO + CaO + SrO + BaO is preferably 25%, more preferably 24.5%, even more preferably 24%, even more preferably 23.5%, even more preferably 23%, even more preferably 22.5%, even more preferably 22%, even more preferably 21.5%, even more preferably 21%, even more preferably 20.5%, and most preferably 20%.

[0042] Mol% ratio (MgO+CaO+SrO+BaO) / Al ２ O ３ This is an important component ratio for ensuring resistance to devitrification, lowering the coefficient of thermal expansion, and increasing meltability. (mol% ratio: (MgO + CaO + SrO + BaO) / Al ２ O ３ If the ratio is too small, the devitrification resistance decreases, the high-temperature viscosity increases, and the meltability decreases, which tends to increase the manufacturing cost of glass plates. Therefore, the mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ The lower limit is preferably 0.5, more preferably 0.6, even more preferably 0.7, even more preferably 0.8, even more preferably 0.9, and most preferably 1. On the other hand, the mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ If the ratio is too large, the coefficient of thermal expansion tends to increase. Therefore, the mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３The upper limit is preferably 2, more preferably 1.9, even more preferably 1.8, even more preferably 1.7, even more preferably 1.6, even more preferably 1.5, even more preferably 1.4, and most preferably 1.3.

[0043] MgO+CaO+SrO+BaO-Al ２ O ３ This is an important parameter for reducing the coefficient of thermal expansion and increasing meltability while ensuring resistance to devitrification. MgO + CaO + SrO + BaO - Al ２ O ３ If the ratio is too small, the devitrification resistance decreases, the high-temperature viscosity increases, and the meltability decreases, which tends to increase the manufacturing cost of glass plates. Therefore, MgO + CaO + SrO + BaO - Al ２ O ３ The lower limit is preferably -2%, more preferably -1.5%, even more preferably -1.2%, even more preferably -1.1%, even more preferably -1%, even more preferably -0.8%, even more preferably -0.5%, even more preferably -0.3%, even more preferably 0%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.5%, even more preferably 0.8%, and most preferably 1%. On the other hand, MgO + CaO + SrO + BaO - Al ２ O ３ If the coefficient of thermal expansion is too large, it tends to increase. Therefore, MgO + CaO + SrO + BaO - Al ２ O ３ The upper limit is preferably 8%, more preferably 7.5%, even more preferably 7%, even more preferably 6.5%, even more preferably 6%, even more preferably 5.5%, even more preferably 5%, even more preferably 4.5%, even more preferably 4%, even more preferably 3.8%, even more preferably 3.7%, even more preferably 3.6%, even more preferably 3.5%, even more preferably 3.4%, even more preferably 3.3%, even more preferably 3.2%, even more preferably 3.1%, and most preferably 3%. MgO + CaO + SrO + BaO - Al ２ O ３ " is calculated from the total amount of MgO, CaO, SrO, and BaO, and Al ２ O ３ This value is obtained by subtracting the mol% content.

[0044] Mol% ratio SiO ２ The ratio of (MgO + CaO + SrO + BaO) is important for increasing meltable properties and strain point. (mol% ratio SiO) ２ If the ratio of (MgO + CaO + SrO + BaO) is too small, the strain point tends to decrease. Therefore, the mol% ratio of SiO ２ The lower limit of / (MgO+CaO+SrO+BaO) is preferably 2.8, more preferably 3, even more preferably 3.2, even more preferably 3.4, even more preferably 3.6, even more preferably 3.7, even more preferably 3.8, even more preferably 3.9, even more preferably 4, even more preferably 4.1, even more preferably 4.2, even more preferably 4.3, and most preferably 4.4. On the other hand, mol% ratio SiO ２ If the ratio of (MgO + CaO + SrO + BaO) is too large, solubility tends to decrease. Therefore, mol% ratio SiO ２ The upper limit of / (MgO+CaO+SrO+BaO) is preferably 9, more preferably 8.8, even more preferably 8.6, even more preferably 8.4, even more preferably 8.2, even more preferably 8, even more preferably 7.8, even more preferably 7.6, even more preferably 7.4, even more preferably 7.2, even more preferably 7, even more preferably 6.8, even more preferably 6.6, even more preferably 6.4, even more preferably 6.2, even more preferably 6, even more preferably 5.8, even more preferably 5.6, and most preferably 5.5.

[0045] Mol% ratio (B ２ O ３ The ratio of (BaO) / MgO is an important component ratio for improving resistance to devitrification. (mol% ratio (B) ２ O ３ If the ratio of (BaO) / MgO is too small, the resistance to devitrification tends to decrease. Therefore, the mol% ratio (B ２ O ３The lower limit of (BaO) / MgO is preferably 0, more preferably greater than 0, even more preferably 0.01, even more preferably 0.02, even more preferably 0.04, even more preferably 0.06, even more preferably 0.08, even more preferably 0.1, even more preferably 0.12, even more preferably 0.14, even more preferably 0.16, even more preferably 0.18, even more preferably 0.2, even more preferably 0.21, even more preferably 0.22, even more preferably 0.25, and most preferably 0.3. On the other hand, the mol% ratio (B ２ O ３ If the ratio of (BaO) / MgO is too large, the coefficient of thermal expansion tends to increase. Therefore, the mol% ratio (B ２ O ３ The upper limit of (BaO) / MgO is preferably 2, more preferably 1.9, even more preferably 1.8, even more preferably 1.7, even more preferably 1.6, even more preferably 1.5, even more preferably 1.4, even more preferably 1.3, even more preferably 1.2, even more preferably 1.1, even more preferably 1, even more preferably 0.98, even more preferably 0.97, even more preferably 0.96, even more preferably 0.95, even more preferably 0.94, even more preferably 0.93, even more preferably 0.92, even more preferably 0.91, even more preferably 0.9, even more preferably 0.89, even more preferably 0.88, even more preferably 0.87, even more preferably 0.86, and most preferably 0.85.

[0046] Y ２ O ３ This is a component that increases Young's modulus and improves meltability. ２ O ３ If the content is too low, the melting properties tend to decrease. Therefore, Y ２ O ３The lower limit of the amount is preferably 0.0001%, more preferably 0.001%, even more preferably 0.002%, even more preferably 0.004%, even more preferably 0.006%, even more preferably 0.008%, even more preferably 0.01%, even more preferably 0.02%, even more preferably 0.04%, even more preferably 0.06%, even more preferably 0.08%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.4%, even more preferably 0.6%, even more preferably 0.8%, and most preferably 1%. ２ O ３ If the content is too high, the resistance to devitrification tends to decrease. Therefore, Y ２ O ３ The upper limit of is preferably 10%, more preferably 9.5%, even more preferably 9%, even more preferably 8.5%, even more preferably 8%, even more preferably 7.5%, even more preferably 7%, even more preferably 6.5%, even more preferably 6%, even more preferably 5.5%, even more preferably 5%, even more preferably 4.8%, even more preferably 4.6%, even more preferably 4.4%, even more preferably 4.2%, even more preferably 4%, even more preferably 3.8%, even more preferably 3.6%, even more preferably 3.4%, even more preferably 3.2%, and most preferably 3%. ２ O ３ Other than Ln ２ O ３ If Y is an essential component, ２ O ３ The content can be 0%.

[0047] Mol% ratio (CaO+SrO) / Y ２ O ３ This is an important component ratio for increasing strain point and devitrification resistance. mol% ratio (CaO + SrO) / Y ２ O ３ If the ratio is too small, the resistance to devitrification tends to decrease. Therefore, the mol% ratio (CaO + SrO) / Y ２ O ３The lower limit is preferably 0.1, more preferably 0.2, even more preferably 0.4, even more preferably 0.6, even more preferably 0.8, even more preferably 1, even more preferably 1.5, even more preferably 2, even more preferably 2.5, even more preferably 2.7, even more preferably 3, even more preferably 3.1, even more preferably 3.2, even more preferably 3.4, even more preferably 3.6, even more preferably 3.8, and most preferably 4. On the other hand, the mol% ratio (CaO + SrO) / Y ２ O ３ If the ratio is too large, the strain point tends to decrease. Therefore, the mol% ratio (CaO + SrO) / Y ２ O ３ The upper limit is preferably 12, more preferably 11, even more preferably 10, even more preferably 9, even more preferably 8.8, even more preferably 8.5, even more preferably 8.2, even more preferably 8, even more preferably 7.8, even more preferably 7.5, even more preferably 7.2, even more preferably 7, even more preferably 6.8, even more preferably 6.6, even more preferably 6.4, even more preferably 6.2, and most preferably 6.

[0048] Ln ２ O ３ This component increases Young's modulus and improves meltability. Ln ２ O ３ If the content is too low, the melting properties tend to decrease. Therefore, Ln ２ O ３ The lower limit is preferably 0.0001%, more preferably 0.001%, even more preferably 0.002%, even more preferably 0.004%, even more preferably 0.006%, even more preferably 0.008%, even more preferably 0.01%, even more preferably 0.02%, even more preferably 0.04%, even more preferably 0.06%, even more preferably 0.08%, even more preferably 0.1%, even more preferably 0.2%, even more preferably 0.4%, even more preferably 0.6%, even more preferably 0.8%, and most preferably 1%. On the other hand, Ln ２ O ３ If the content is too high, the resistance to devitrification tends to decrease. Therefore, Ln ２ O ３The upper limit of the amount is preferably 10%, more preferably 9.5%, even more preferably 9%, even more preferably 8.5%, even more preferably 8%, even more preferably 7.5%, even more preferably 7%, even more preferably 6.5%, even more preferably 6%, even more preferably 5.5%, even more preferably 5%, even more preferably 4.8%, even more preferably 4.6%, even more preferably 4.4%, even more preferably 4.2%, even more preferably 4%, even more preferably 3.8%, even more preferably 3.6%, even more preferably 3.4%, even more preferably 3.2%, and most preferably 3%.

[0049] Mol% ratio (CaO+SrO) / Ln ２ O ３ This is an important component ratio for increasing strain point and devitrification resistance. (mol% ratio: (CaO + SrO) / Ln ２ O ３ If the ratio is too small, the resistance to devitrification tends to decrease. Therefore, the mol% ratio (CaO + SrO) / Ln ２ O ３ The lower limit is preferably 0.1, more preferably 0.2, even more preferably 0.4, even more preferably 0.6, even more preferably 0.8, even more preferably 1, even more preferably 1.5, even more preferably 2, even more preferably 2.5, even more preferably 2.7, even more preferably 3, even more preferably 3.1, even more preferably 3.2, even more preferably 3.4, even more preferably 3.6, even more preferably 3.8, and most preferably 4. On the other hand, the mol% ratio (CaO + SrO) / Ln ２ O ３ If the ratio is too large, the strain point tends to decrease. Therefore, mol% ratio (CaO + SrO) / Ln ２ O ３ The upper limit is preferably 12, more preferably 11, even more preferably 10, even more preferably 9, even more preferably 8.8, even more preferably 8.5, even more preferably 8.2, even more preferably 8, even more preferably 7.8, even more preferably 7.5, even more preferably 7.2, even more preferably 7, even more preferably 6.8, even more preferably 6.6, even more preferably 6.4, even more preferably 6.2, and most preferably 6.

[0050] A suitable glass composition range can be obtained by appropriately combining the preferred content ranges of each component, but among these, in order to optimize the effect of the present invention, the glass composition is set to mol% of SiO ２ 65-73%, Al ２ O ３ 10-15%, B ２ O ３ 0-2%, Li ２ O + Na ２ O+K ２ O 0-0.5%, MgO 1-8%, CaO 0-10%, SrO 0-6%, BaO 0-5%, MgO+CaO+SrO+BaO 8-25%, Y ２ O ３ It contains 0.1-5% of the substance, in mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ 0.8 to 1.5, mol% ratio (CaO+SrO) / Y ２ O ３ 1 to 10, mol% ratio SiO ２ / (MgO+CaO+SrO+BaO) 3-6, mol% ratio (B ２ O ３ It is particularly preferable that the ratio of (BaO) / MgO is 0 to 0.9.

[0051] In addition to the above components, the following components may be added as optional components. However, from the viewpoint of effectively enjoying the effects of the present invention, the total amount of other components is preferably 2% or less, and particularly preferably 1% or less.

[0052] SnO ２ This component has a good clarifying effect in the high-temperature range, as well as increasing the strain point and reducing high-temperature viscosity. SnO ２ The content is preferably 0 to 1%, 0.001 to 1%, 0.01 to 0.5%, and particularly preferably 0.05 to 0.3%. SnO ２ If the content is too high, SnO ２ Devitrified crystals of SnO are more likely to precipitate. ２ If the content is less than 0.001%, it will be difficult to enjoy the above effects.

[0053] As stated above, SnO ２While is suitable as a clarifying agent, as long as the glass properties are not impaired, SnO ２ Instead, or SnO ２ Along with F, SO ３ Metal powders such as C, Al, or Si can be added in amounts up to 5% each (preferably up to 1%, particularly preferably up to 0.5%). In addition, CeO can be used as a clarifying agent. ２ F and other compounds can also be added up to 2% each (preferably up to 1%, and especially preferably up to 0.5%).

[0054] As a clarifying agent, ２ O ３ Sb ２ O ３ This is also effective. However, As ２ O ３ Sb ２ O ３ It is a component that increases the environmental burden. Also, As ２ O ３ These are components that reduce solarization resistance. Therefore, it is preferable that the alkali-free glass plate of the present invention substantially does not contain these components.

[0055] Cl is a component that promotes the initial melting of glass batches. Furthermore, the addition of Cl can enhance the action of clarifying agents. As a result, melting costs can be reduced while extending the lifespan of the glass manufacturing furnace. However, if the Cl content is too high, the strain point tends to decrease. Therefore, the Cl content is preferably 0-2%, more preferably 0.0005-1%, and particularly preferably 0.001-0.5%. As a raw material for introducing Cl, alkaline earth metal oxides such as strontium chloride, or raw materials such as aluminum chloride can be used.

[0056] Fe ２ O ３ Fe is a component that is inevitably mixed in from the glass raw materials and is also a component that reduces electrical resistivity. ２ O ３ The upper limit of the content is preferably 0.05%, 0.03%, and particularly preferably 0.01%. Fe ２ O ３If the content is too high, the electrical resistivity of the molten glass increases, making electromelting difficult. ２ O ３ The lower limit of the content is not particularly limited and may be 0%, but if it is too low, raw material costs tend to increase, so it is preferably 0.001%, and particularly preferably 0.002%.

[0057] P ２ O ５ This component increases the strain point and is also capable of significantly suppressing the precipitation of devitrified crystals of alkaline earth aluminosilicates such as anorthite. However, P ２ O ５ When a large amount of P is included, the glass becomes more prone to phase separation. ２ O ５ The content is preferably 0 to 2%, more preferably 0 to 1.5%, even more preferably 0 to 0.5%, even more preferably 0 to 0.3%, even more preferably less than 0 to 0.1%, and particularly preferably less than 0 to 0.01%.

[0058] TiO ２ It is a component that lowers high-temperature viscosity and increases meltability, as well as a component that suppresses solarization, but TiO ２ If a large amount of TiO is included, the glass will become colored and its transmittance will easily decrease. ２ The content is preferably 0 to 2%, more preferably 0.0005 to 1%, even more preferably 0.001 to 0.5%, and particularly preferably 0.005 to 0.1%.

[0059] ZnO is a component that increases Young's modulus. However, if a large amount of ZnO is included, the glass becomes more prone to devitrification and the strain point tends to decrease. The ZnO content is preferably 0 to 2%, more preferably 0 to 1.5%, even more preferably 0 to 1%, even more preferably 0 to 0.8%, even more preferably 0 to 0.5%, and particularly preferably less than 0 to 0.5%.

[0060] ZrO ２ This is a component that increases Young's modulus. However, ZrO ２ If a large amount of ZrO is included, the glass becomes more prone to devitrification. ２The content is preferably 0 to 2%, more preferably 0.0005 to 1%, even more preferably 0.001 to 0.5%, and particularly preferably 0.005 to 0.1%.

[0061] MOO ３ It is a component that absorbs ultraviolet light (light with a wavelength of 200-300 nm). Also, MoO ３ This is a component that reduces the water content in the glass. In particular, when the raw material batch is melted by electric melting and heating, MoO ３ By including this, the amount of water in the glass can be further reduced. When the amount of water in the glass decreases, the liquid-phase viscosity and strain point increase, improving the glass's resistance to devitrification and heat resistance. MoO ３ The lower limit of is preferably 0.00001%, more preferably 0.00005%, even more preferably 0.0001%, even more preferably 0.0002%, even more preferably 0.0003%, even more preferably 0.0004%, and particularly preferably 0.001%. On the other hand, MoO ３ If the content is too high, it reduces the transmittance of ultraviolet light, which tends to lower the yield, especially in the laser delamination process, within the display manufacturing process. Therefore, MoO ３ The upper limit of the amount is preferably 0.01%, more preferably 0.008%, even more preferably 0.006%, even more preferably 0.005%, even more preferably 0.004%, and particularly preferably 0.003%.

[0062] The alkali-free glass plate of the present invention preferably has the following characteristics.

[0063] The average coefficient of thermal expansion in the temperature range of 30 to 380°C is preferably 28 × 10⁻⁶. －７ ~60 x 10 －７ / ℃, 30×10 －７ ~55 x 10 －７ / ℃, 31 × 10 －７ ~54 x 10 －７ / ℃, 32×10 －７ ~53 x 10 －７ / ℃, 33 × 10 －７ ~52 x 10 －７ / ℃, particularly preferably 35 × 10 －７ ~51 x 10 －７The temperature is / °C. This makes it easier to match the thermal expansion coefficient of Si used in TFTs.

[0064] The Young's modulus is preferably 80 GPa or higher, 80.5 GPa or higher, 81 GPa or higher, 81.5 GPa or higher, 82 GPa or higher, 82.3 GPa or higher, 82.5 GPa or higher, 82.8 GPa or higher, 83 GPa or higher, 83.3 GPa or higher, 83.5 GPa or higher, 83.8 GPa or higher, and particularly preferably 84 to 120 GPa. If the Young's modulus is too low, defects caused by the bending of the glass plate are more likely to occur.

[0065] The specific Young's modulus is preferably 29 GPa / g·cm ３ Above, 29.5GPa / g・cm ３ Above, 30GPa / g・cm ３ Above, 30.5GPa / g・cm ３ Above, 31GPa / g・cm ３ Above, 31.3GPa / g・cm ３ Above, 31.5GPa / g・cm ３ In particular, 32 to 39 GPa / g·cm is preferred. ３ Therefore, if the Young's modulus is too low, problems caused by the bending of the glass plate are more likely to occur.

[0066] The strain point is preferably 740°C or higher, 743°C or higher, 745°C or higher, 748°C or higher, 750°C or higher, 753°C or higher, and particularly preferably 755 to 820°C. In this way, thermal shrinkage of the glass plate can be suppressed in the LTPS process.

[0067] The annealing point is preferably 790°C or higher, 795°C or higher, 800°C or higher, 803°C or higher, 805°C or higher, 808°C or higher, and particularly preferably 810°C to 900°C. In this way, thermal shrinkage of the glass plate can be suppressed in the LTPS process.

[0068] The upper limit of the liquidus temperature is preferably 1360°C or lower, 1350°C or lower, 1340°C or lower, 1330°C or lower, 1320°C or lower, 1310°C or lower, 1300°C or lower, 1290°C or lower, and particularly preferably 1280°C or lower, while the lower limit is preferably 1100°C or higher, 1120°C or higher, 1140°C or higher, 1150°C or higher, and particularly preferably 1160°C or higher. This makes it easier to prevent the formation of devitrified crystals during glass manufacturing, which can reduce productivity. Furthermore, it makes it easier to form using the overflow down-draw method, which improves the surface quality of the glass plate and reduces the manufacturing cost of the glass plate. Note that the liquidus temperature is an indicator of devitrification resistance, and the lower the liquidus temperature, the better the devitrification resistance.

[0069] The lower limit of the liquid phase viscosity is preferably 10 ３．９ dPa·s or higher, 10 ４．０ dPa·s or higher, 10 ４．１ dPa·s or higher, 10 ４．２ dPa·s or higher, 10 ４．３ dPa·s or higher, particularly preferably 10 ４．５ It is dPa·s or higher, and the upper limit is 10 ７．４ dPa・s or less, 10 ７．２ dPa・s or less, 10 ７．０ dPa·s or less, particularly preferably 10 ６．０ The viscosity is dPa·s or less. This makes devitrification less likely to occur during molding, making it easier to mold using the overflow downdraw method. As a result, it is possible to improve the surface quality of the glass plate and reduce the manufacturing cost of the glass plate. Note that liquid-phase viscosity is an indicator of devitrification resistance and moldability; the higher the liquid-phase viscosity, the better the devitrification resistance and moldability.

[0070] High temperature viscosity 10 ２．５ The temperature at dPa·s is preferably 1700°C or lower, 1680°C or lower, 1650°C or lower, and particularly preferably 1500 to 1600°C. High-temperature viscosity 10 ２．５ If the temperature at dPa·s is too high, it becomes difficult to melt the glass batch, and the manufacturing cost of the glass plates increases. ２．５ The temperature in dPa·s corresponds to the melting temperature, and the lower this temperature, the better the meltability.

[0071] The β-OH value is an indicator of the water content in the glass, and lowering the β-OH value can raise the strain point. Furthermore, even with the same glass composition, a smaller β-OH value results in a smaller thermal shrinkage rate at temperatures below the strain point. The β-OH value is preferably 0.55 / mm or less, 0.5 / mm or less, 0.45 / mm or less, 0.4 / mm or less, 0.35 / mm or less, 0.3 / mm or less, and particularly preferably 0.25 / mm or less. However, if the β-OH value is too low, the meltability tends to decrease. Therefore, the β-OH value is preferably 0.01 / mm or more, and particularly preferably 0.03 / mm or more.

[0072] The following methods can be used to lower the β-OH value: (1) Select raw materials with low water content. (2) Add components that lower the β-OH value (Cl, SO) to the glass. ３ (3) Add (etc.). (4) Reduce the amount of moisture in the furnace atmosphere. (5) N in the molten glass. ２ (5) Use a small melting furnace. (6) Increase the flow rate of molten glass. (7) Use an electromelting method.

[0073] Here, "β-OH value" refers to the value obtained by measuring the transmittance of glass using FT-IR and using the following formula.

[0074] β-OH value = (1 / X) log １０ (T １ / T ２ ) X: Plate thickness (mm) T １ :Reference wavelength 3846cm －１ Transmittance (%) in T ２ Hydroxyl group absorption wavelength: 3600 cm －１ Minimum transmittance in the vicinity (%)

[0075] The alkali-free glass plate of the present invention is preferably formed by the overflow downdraw method. The overflow downdraw method is a method of manufacturing a glass plate by allowing molten glass to overflow from both sides of a heat-resistant trough-shaped structure, and then stretching and forming the overflowed molten glass downwards while it is brought together at the lower end of the trough-shaped structure. In the overflow downdraw method, the surface that will become the surface of the glass plate does not come into contact with the trough-shaped refractory material and is formed in a free surface state. Therefore, it is possible to manufacture glass plates with an unpolished, forged surface with good surface quality at low cost, and thinning is also easy.

[0076] The alkali-free glass plate of the present invention may also be formed by the float process. In this way, large glass plates can be manufactured inexpensively.

[0077] When the alkali-free glass plate of the present invention is used in a magnetic recording medium, it is preferable that the surface is polished. Polishing the glass surface can reduce the overall plate thickness deviation TTV. As a result, the magnetic film can be properly formed, making it suitable as a substrate for a magnetic recording medium. On the other hand, when used in an organic EL device, it is preferable that the surface is a forged surface (i.e., an unpolished surface) formed by the overflow downdraw method.

[0078] In the alkali-free glass plate of the present invention, the plate thickness is not particularly limited, but when used in organic EL devices, a thickness of less than 0.7 mm, 0.6 mm or less, less than 0.6 mm, and particularly 0.05 to 0.5 mm is preferred. The thinner the plate thickness, the lighter the organic EL device can be made. The plate thickness can be adjusted by the flow rate and plate drawing speed during glass manufacturing. On the other hand, when used in magnetic recording media, the plate thickness is preferably 1.5 mm or less, 1.2 mm or less, 0.2 to 1.0 mm, and particularly preferably 0.3 to 0.9 mm. If the plate thickness is too thick, etching to the desired plate thickness is required, which may increase processing costs.

[0079] In the alkali-free glass plate of the present invention, when used in an organic EL device, the average surface roughness Ra of the surface is preferably 1.0 nm or less, 0.5 nm or less, and particularly preferably 0.2 nm or less. If the average surface roughness Ra of the surface is large, it becomes difficult to accurately pattern electrodes and the like in the display manufacturing process, which increases the probability of circuit electrodes breaking or short-circuiting, making it difficult to guarantee the reliability of the display and the like. Here, "average surface roughness Ra of the surface" refers to the average surface roughness Ra of the main surface (i.e., both surfaces) excluding the end face, and can be measured, for example, by an atomic force microscope (AFM).

[0080] When the alkali-free glass plate of the present invention is used as a substrate for an organic EL television display panel or as a carrier for manufacturing organic EL display panels, it is preferable that its shape is rectangular.

[0081] The alkali-free glass plate of the present invention is suitable as a substrate for magnetic recording media, particularly energy-assisted magnetic recording media. To increase the degree of orderliness (i.e., regularity) of the magnetic layer and achieve a high Ku content, the substrate is heat-treated at a high temperature of approximately 800°C during or before / after deposition of the magnetic layer. The alkali-free glass plate of the present invention possesses properties that can withstand such heat treatment. Furthermore, the alkali-free glass plate of the present invention can withstand the impacts associated with the high rotation of the magnetic recording media. The alkali-free glass plate of the present invention is processed into a disk shape by cutting or other processing. In this case, it is preferable that a circular opening is formed in the center.

[0082] The present invention will be described below based on examples. Note that the following examples are merely illustrative. The present invention is not limited in any way to the following examples.

[0083] Tables 1 to 5 show examples of the present invention (samples No. 1 to 38).

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] First, glass batches prepared with glass raw materials to achieve the glass composition shown in the table were placed in a platinum crucible and melted at 1600-1680°C for 24 hours. During the melting of the glass batches, a platinum stirrer was used to stir and homogenize them. 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 obtained sample, the average thermal expansion coefficient CTE, density ρ, Young's modulus E, specific Young's modulus E / ρ, strain point Ps, annealing point Ta, softening point Ts, and high-temperature viscosity 10 were recorded in the temperature range of 30-380°C. ４ Temperature and high-temperature viscosity at dPa·s 10 ３ Temperature and high-temperature viscosity at dPa·s 10 ２．５ Temperature, liquidus temperature TL, and liquidus viscosity (i.e., viscosity at liquidus temperature TL) in dPa·s log １０ We evaluated ηTL.

[0090] The average thermal expansion coefficient CTE in the temperature range of 30 to 380°C is the value measured using a dilatometer.

[0091] The density ρ is a value measured by the well-known Archimedes method.

[0092] Young's modulus E refers to the value measured using a well-known resonance method.

[0093] The relative Young's modulus E / ρ is the value obtained by dividing Young's modulus by density.

[0094] The strain point Ps, annealing point Ta, and softening point Ts were measured according to the ASTM C336 and C338 methods.

[0095] High temperature viscosity 10 ４ dPa·s, 10 ３ dPa·s, 10 ２．５ The temperature in dPa·s was measured using the platinum ball pulling method.

[0096] The liquidus temperature TL is the temperature at which crystals precipitate after the glass powder that passes through a standard 30-mesh (500 μm) sieve and remains in a 50-mesh (300 μm) sieve is placed in a platinum boat and held in a temperature gradient furnace for 24 hours.

[0097] liquidus viscosity log １０ ηTL is the viscosity of the glass at the liquidus temperature TL, measured using the platinum ball pulling method.

[0098] As is clear from the table, since the glass composition of samples No. 1 to 38 is restricted to a predetermined range, the Young's modulus is 86 GPa or higher, the strain point is 760°C or higher, the liquidus temperature is 1328°C or lower, and the liquidus viscosity is 10 ４．１ The strain is greater than dPa·s. Therefore, samples No. 1 to 38 exhibit excellent productivity and achieve the desired strain point and Young's modulus.

[0099] The alkali-free glass plate of the present invention is suitable as a substrate for organic EL devices, particularly for display panels for organic EL televisions, and as a carrier for manufacturing organic EL display panels. In addition, the alkali-free glass plate of the present invention is suitable as a substrate for displays such as liquid crystal displays, a cover glass for image sensors such as charge-coupled devices (CCDs) and 1:1 proximity solid-state image sensors (CIS), a substrate and cover glass for solar cells, and a substrate for organic EL lighting. Furthermore, because the alkali-free glass plate of the present invention has a sufficiently high strain point and Young's modulus, it is also suitable as a glass substrate for magnetic recording media.

Claims

1. As a glass composition, in mol%, SiO ２ 65 - 73%, Al ２ O ３ 10 - 15%, B ２ O ３ 0 - 5%, Li ２ O + Na ２ O + K ２ O 0 - 0.5%, MgO 0.1 - 8%, CaO 0 - 10%, SrO 0 - 6%, BaO 0 - 5%, MgO + CaO + SrO + BaO 8 - 25%, Y ２ O ３ 0.0001 - 10% is contained, and the mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ is 0.5 - 2, the mol% ratio (CaO + SrO) / Y ２ O ３ is 0.1 - 12, the mol% ratio SiO ２ / (MgO + CaO + SrO + BaO) is 2.8 - 9, and the mol% ratio (B ２ O ３ + BaO) / MgO is 0 - 2. A soda - lime - free glass sheet is characterized by the above.

2. The glass composition is SiO2 in mol%. ２ 65-73%, Al ２ O ３ 10-15%, B ２ O ３ 0-2%, Li ２ O + Na ２ O+K ２ O 0-0.5%, MgO 1-8%, CaO 0-10%, SrO 0-6%, BaO 0-5%, MgO+CaO+SrO+BaO 8-25%, Y ２ O ３ It contains 0.1-5% of the substance, in mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ 0.8 to 1.5, mol% ratio (CaO+SrO) / Y ２ O ３ 1 to 10, mol% ratio SiO ２ / (MgO+CaO+SrO+BaO) 3-6, mol% ratio (B ２ O ３ The alkali-free glass plate according to claim 1, characterized in that the ratio of (BaO) / MgO is 0 to 0.

9.

3. The glass composition is mol% SnO ２ The alkali-free glass plate according to claim 1 or 2, characterized by containing 0.001 to 1%.

4. As for the glass composition, As ２ O ３ and Sb ２ O ３ The alkali-free glass plate according to claim 1 or 2, characterized in that it substantially does not contain [the specified substance].

5. The average coefficient of thermal expansion in the temperature range of 30 to 380°C is 28 × 10⁻⁶. －７ ~60 x 10 －７ The alkali-free glass plate according to claim 1 or 2, characterized in that it is / ℃.

6. The alkali-free glass plate according to claim 1 or 2, characterized in that the Young's modulus is 80 GPa or higher.

7. The relative Young's modulus is 29 GPa / g·cm. ３ The alkali-free glass plate according to claim 1 or 2, characterized in that it is as described above.

8. The alkali-free glass plate according to claim 1 or 2, characterized in that its strain point is 740°C or higher.

9. The alkali-free glass plate according to claim 1 or 2, characterized in that its annealing point is 790°C or higher.

10. The alkali-free glass plate according to claim 1 or 2, characterized in that the liquidus temperature is 1360°C or lower.

11. Liquid phase viscosity is 10 ３．９ The alkali-free glass plate according to claim 1 or 2, characterized in that it has a dPa·s or higher.

12. The alkali-free glass plate according to claim 1 or 2, characterized in that it is used in an organic EL device.

13. The alkali-free glass plate according to claim 1 or 2, characterized in that it is used in a magnetic recording medium.

14. The glass composition is SiO2 in mol%. ２ 65-73%, Al ２ O ３ 10-15%, B ２ O ３ 0-5%, Li ２ O + Na ２ O+K ２ O 0-0.5%, MgO 0.1-8%, CaO 0-10%, SrO 0-6%, BaO 0-5%, MgO+CaO+SrO+BaO 8-25%, Ln ２ O ３ It contains 0.0001 to 10%, in mol% ratio (MgO + CaO + SrO + BaO) / Al ２ O ３ 0.5-2, mol% ratio (CaO+SrO) / Ln ２ O ３ 0.1-12, mol% ratio SiO ２ / (MgO+CaO+SrO+BaO) 2.8-9, mol% ratio (B ２ O ３ A non-alkali glass plate characterized by having a ratio of +BaO) / MgO 0 to 2.

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