CN117295698A - Alkali-free glass plate - Google Patents

Abstract

The alkali-free glass plate of the present invention is characterized by comprising, as a glass composition, in mol%: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～15％、B ₂ O ₃ 0～3％、Li ₂ O+Na ₂ O+K ₂ 0 to 0.5 percent of O, 6 to 12 percent of MgO, 9 to 13 percent of CaO, 0 to 2 percent of SrO and 0 to 1 percent of BaO, and the mol percent ratio is SrO/SiO ₂ 0 to 0.03.

Description

Alkali-free glass plate

Technical Field

The present invention relates to an alkali-free glass plate, and more particularly, to an alkali-free glass plate suitable for organic EL displays and magnetic storage media.

Background

Electronic devices such as organic EL displays are used for flexible devices, displays for mobile phones, and the like because of their thin shape, excellent dynamic image display, and low power consumption.

As a substrate of the organic EL display, a glass plate is widely used. The glass sheet for this use is required to have the following characteristics.

(1) In order to prevent alkali ions from diffusing into the semiconductor material formed in the heat treatment step, the alkali metal oxide is hardly contained, that is, alkali-free glass (glass having an alkali oxide content of 0.5mol% or less in the glass composition),

(2) In order to reduce the price of glass sheets, the glass sheets are formed by an overflow downdraw method which is easy to improve the surface quality, and the glass sheets are excellent in productivity, particularly excellent in meltability and devitrification resistance,

(3) In LTPS (low temperature poly silicon: low temperature polysilicon) process and oxide TFT process, strain point is increased to reduce thermal shrinkage of glass plate.

In addition, with the development of information-related infrastructure technology, the demand for information storage media such as magnetic disks and optical disks has increased dramatically.

As a substrate for an information storage medium, a glass plate is widely used instead of a conventional aluminum alloy substrate. In recent years, in order to cope with the demand for higher storage density, a magnetic storage medium using an energy-assisted magnetic storage system, i.e., an energy-assisted magnetic storage medium, has been studied. For the energy-assisted magnetic storage medium, a glass plate is also used, and a magnetic layer or the like is formed on the surface of the glass plate. In the energy-assisted magnetic storage medium, as a magnetic material of the magnetic layer, an ordered alloy having a large magnetic anisotropy coefficient Ku (hereinafter, referred to as "high Ku") is used.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-106919

Patent document 2: japanese patent laid-open No. 2021-086643

Disclosure of Invention

Technical problem to be solved by the invention

However, organic EL devices are also widely developed in organic EL televisions. The organic EL television is strongly demanded to be large and thin, and the demand for high-resolution displays such as 8K is increasing. Accordingly, glass sheets for these applications are required to have a large size and a thin shape, and to have thermal dimensional stability that can meet the high resolution requirements. In addition, in the organic EL television, low cost is demanded for reducing the price difference from the liquid crystal display, and low cost is demanded for the glass plate as well. However, if the glass plate is made larger and thinner, the glass plate is likely to flex, and the manufacturing cost increases.

Glass sheets formed by glass manufacturers are subjected to cutting, annealing, inspection, cleaning, and other steps, but in these steps, the glass sheets are put into cassettes in which a multi-layered shelf is formed, and are carried out. The cassette can normally hold glass sheets in a horizontal direction by placing opposite sides of the glass sheets on shelves formed on the left and right inner surfaces, but since a large and thin glass sheet is deflected by a large amount, a part of the glass sheet is likely to be broken by contact with the cassette when the glass sheet is put into the cassette, or is likely to be largely swung and unstable when the glass sheet is carried out. This form of cartridge is also used by electronic device manufacturers and therefore suffers from the same drawbacks. In order to solve this problem, it is effective to increase the Young's modulus of the glass sheet and reduce the deflection.

In addition, as described above, in LTPS process and oxide TFT process for obtaining a high resolution display, it is necessary to increase the strain point of the glass plate in order to reduce the thermal shrinkage of the large glass plate.

However, if the young's modulus and strain point of the glass sheet are to be improved, the balance of the glass composition is impaired, the productivity is lowered, and in particular, the devitrification resistance tends to be significantly lowered, and the viscosity of the liquid phase increases, so that the glass sheet cannot be formed by the overflow downdraw method. In addition, the melting property is lowered, or the molding temperature of the glass is increased, and the life of the molded article is easily shortened. As a result, the original plate cost of the glass plate increases.

In addition, in order not to generate large deformation at the time of high-speed rotation, the glass plate for a magnetic storage medium is required to have high rigidity (young's modulus). Specifically, in a disk-shaped magnetic storage medium, a magnetic head is moved in a radial direction while rotating the medium around a central axis at a high speed, and information is written and read in the rotation direction. In recent years, the rotational speed for increasing the writing speed and the reading speed has been increased from 5400rpm to 7200rpm and further to 10000rpm, but in disk-shaped magnetic storage media, the position where information is stored is allocated in advance according to the distance from the central axis. Therefore, if the glass plate is deformed during rotation, the head position is shifted, and it is difficult to perform accurate reading.

In recent years, a DFH (Dynamic Flying Height: dynamic flying height) mechanism has been mounted on a magnetic head to greatly reduce the gap between a storage/playback element portion of the magnetic head and the surface of a magnetic storage medium (reduce the flying height), thereby achieving higher storage density. The DFH mechanism is a mechanism in which a heating unit such as a very small heater is provided near a storage/playback element unit of a magnetic head, and only the element unit periphery is thermally expanded in the medium surface direction. By providing such a mechanism, the distance between the magnetic head and the magnetic layer of the medium becomes short, and therefore, a smaller signal of the magnetic particles can be picked up, and a higher storage density can be achieved. On the other hand, since the gap between the storage/playback element portion of the magnetic head and the surface of the magnetic storage medium is extremely small, for example, 2nm or less, there is a concern that the magnetic head may collide with the surface of the magnetic storage medium even with a minute impact. The higher the rotation speed, the more remarkable the tendency. Therefore, at the time of high-speed rotation, it is important to prevent the occurrence of deflection and vibration (chatter) of the glass plate, which are the cause of the collision.

In order to increase the degree of ordering (degree of ordering) of the magnetic layer and to achieve a higher Ku, a substrate including a glass plate may be heat-treated at a high temperature of about 800 ℃ during or before or after the formation of the magnetic layer. As the storage density increases, the heat treatment temperature needs to be increased, and therefore, higher heat resistance, that is, higher strain point than the conventional glass plate for a magnetic storage medium is required. After the magnetic layer is formed, laser irradiation may be performed on a substrate including a glass plate. Such heat treatment and laser irradiation also have the purpose of increasing the annealing temperature and coercive force of the magnetic layer containing FePt-based alloy or the like.

However, when the young's modulus and strain point of the glass sheet are increased as described above, the balance of the glass composition is broken, the productivity is lowered, and particularly the devitrification resistance is significantly lowered, and the viscosity of the liquid phase is increased, so that the glass sheet cannot be formed by the overflow downdraw method. In addition, the melting property is lowered, or the molding temperature of the glass is increased, and the life of the molded article is easily shortened. As a result, the original plate cost of the glass plate increases.

Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an alkali-free glass sheet having excellent productivity and sufficiently high strain point and young's modulus.

Means for solving the problems

The present inventors have repeatedly conducted various experiments, and as a result, have found that the above technical problems can be solved by strictly restricting the glass composition of an alkali-free glass plate, and have been proposed as the present invention. That is, the alkali-free glass sheet of the present invention is characterized by comprising, in mol%, as a glass composition: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～16％、B ₂ O ₃ 0～3％、Li ₂ O+Na ₂ O+K ₂ 0 to 0.5 percent of O, 6 to 12 percent of MgO, 9 to 13 percent of CaO, 0 to 2 percent of SrO and 0 to 1 percent of BaO, and the mol percent ratio is SrO/SiO ₂ 0 to 0.03. Here, "Li ₂ O+Na ₂ O+K ₂ O "means Li ₂ O、Na ₂ O and K ₂ Total amount of O. "SrO/SiO ₂ "dividing the mole% content of SrO by SiO ₂ A mol% content of (C).

The alkali-free glass sheet of the present invention preferably has, as a glass composition, in mol%, the following components: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～16％、B ₂ O ₃ 0 to less than 1 percent, li ₂ O+Na ₂ O+K ₂ O 0～0.5%, mgO 6-12%, caO 9-13%, srO more than 0 and less than 2%, baO 0-1%, and mole% ratio SrO/SiO ₂ 0 to 0.008.

In addition, the alkali-free glass sheet of the present invention preferably contains substantially no As in the glass composition ₂ O ₃ 、Sb ₂ O ₃ . Here, "substantially no As contained ₂ O ₃ "means As ₂ O ₃ The content of (2) is 0.05mol% or less. "substantially free of Sb ₂ O ₃ "means Sb ₂ O ₃ The content of (2) is 0.05mol% or less.

The alkali-free glass sheet of the present invention preferably further contains 0.001mol% to 1mol% of SnO ₂ 。

The alkali-free glass sheet of the present invention preferably has a Young's modulus of 83GPa or more, a strain point of 730 ℃ or more, and a liquid phase temperature of 1350 ℃ or less. Herein, "Young's modulus" refers to a value measured by a bending resonance method. In addition, 1GPa corresponds to about 101.9Kgf/mm ² . "strain point" refers to a value measured based on the method of ASTM C336. The "liquidus temperature" means a temperature at which glass powder passing through a standard sieve of 30 mesh (500 μm) and remaining at 50 mesh (300 μm) is put into a platinum boat and kept in a temperature gradient furnace for 24 hours, and then crystallized.

The alkali-free glass sheet of the present invention preferably has a strain point of 735 ℃ or higher.

In addition, the alkali-free glass sheet of the present invention preferably has a Young's modulus of more than 84GPa.

The alkali-free glass sheet of the present invention preferably has an average thermal expansion coefficient of 30X 10 in a temperature range of 30 to 380 DEG C ^-7 ～50×10 ^-7 and/C. The "average thermal expansion coefficient in the temperature range of 30 to 380 ℃ may be measured by an dilatometer".

In addition, the alkali-free glass sheet of the present invention preferably has a liquid phase viscosity of 10 ^4.0 dPa.s or more. The "liquid phase viscosity" herein means a glass viscosity at a liquid phase temperature, which can be measured by a platinum ball pulling method.

In addition, the alkali-free glass sheet of the present invention is preferably used for organic EL devices.

In addition, the alkali-free glass sheet of the present invention is preferably used for magnetic storage media.

Drawings

Fig. 1 is an upper perspective view for showing a disk shape.

Symbol description

1-disc substrate

Detailed Description

The alkali-free glass plate of the present invention is characterized by comprising, as a glass composition, in mol%: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～16％、B ₂ O ₃ 0～3％、Li ₂ O+Na ₂ O+K ₂ 0 to 0.5 percent of O, 6 to 12 percent of MgO, 9 to 13 percent of CaO, 0 to 2 percent of SrO and 0 to 1 percent of BaO, and the mol percent ratio is SrO/SiO ₂ 0 to 0.03. The reason why the content of each component is limited as described above is shown below. In the description of the content of each component, unless otherwise specified, the expression% represents mol%.

SiO ₂ Is a component forming the skeleton of glass. If SiO ₂ If the content of (2) is too small, the thermal expansion coefficient becomes high and the density increases. Thus, siO ₂ The lower limit amount of the catalyst is preferably 64%, more preferably 64.2%, more preferably 64.5%, more preferably 64.8%, more preferably 65%, more preferably 65.5%, more preferably 65.8%, more preferably 66%, more preferably 66.3%, more preferably 66.5%, and most preferably 66.7%. On the other hand, siO ₂ If the content of (C) is too large, young's modulus decreases, high-temperature viscosity increases, heat required for melting increases, melting cost increases, and SiO becomes high ₂ The introduced raw material of (2) may cause dissolution residue, which may cause a decrease in yield. In addition, devitrification crystals such as cristobalite are likely to precipitate, and the viscosity of the liquid phase is likely to decrease. Thus, siO ₂ The upper limit amount of the catalyst is preferably 72%, more preferably 71.8%, more preferably 71.6%, more preferably 71.4%, more preferably 71.2%, more preferably 71%, more preferably 70.8%, more preferably 70.6%, and most preferably 70.4%％。

Al ₂ O ₃ The component forming the glass skeleton, the component increasing Young's modulus, and the component increasing strain point. If Al is ₂ O ₃ If the content of (2) is too small, young's modulus tends to be low, and strain point tends to be low. Thus, al ₂ O ₃ The lower limit amount of (c) is preferably 12%, more preferably 12.2%, more preferably 12.4%, even more preferably more than 12.4%, even more preferably 12.5%, and most preferably more than 12.5%. On the other hand, if Al ₂ O ₃ If the content of (b) is too large, devitrification crystals such as mullite tend to precipitate, and the liquid phase viscosity tends to decrease. Thus, al ₂ O ₃ The upper limit amount of the catalyst is preferably 16%, more preferably 15.8%, more preferably 15.5%, more preferably 15.3%, more preferably 15%, more preferably 14.8%, more preferably 14.6%, more preferably 14.4%, more preferably 14.2%, more preferably 14%, more preferably 13.9%, more preferably 13.8%, more preferably 13.7%, and most preferably 13.6%.

B ₂ O ₃ Not essential components, but if B is present ₂ O ₃ The effect of improving the meltability and the devitrification resistance can be obtained. Thus B ₂ O ₃ The lower limit amount of (2) is preferably 0%, more preferably more than 0%, more preferably 0.1%, even more preferably 0.2%, even more preferably 0.3%, even more preferably 0.4%, and most preferably 0.5%. On the other hand, if B ₂ O ₃ If the content of (B) is too large, young's modulus and strain point tend to be lowered. Thus B ₂ O ₃ The upper limit amount of the catalyst is preferably 3%, more preferably 2.9%, more preferably 2.8%, more preferably 2.7%, more preferably 2.6%, more preferably 2.5%, more preferably 2%, more preferably 2.8%, more preferably 2.6%, more preferably 2.4%, more preferably 2.2%, more preferably 2%, more preferably 1.8%, more preferably 1.6%, more preferably 1.4%, more preferably 1.2%, more preferably 1%, most preferably less than 1%.

Li ₂ O、Na ₂ O and K ₂ O is an inevitable component mixed from the glass raw material, and the total amount thereof is 0 to 0.5%, preferably 0 to 0.4%, more preferably 0 to 0.3%, even more preferably 0.005 to 0.2%, and most preferably 0.01 to 0.1%. If Li ₂ O、Na ₂ O and K ₂ If the total amount of O is too large, alkali ions may diffuse into the semiconductor material formed in the heat treatment step. Li ₂ O、Na ₂ O and K ₂ The individual content of O is preferably 0 to 0.5%, more preferably 0 to 0.4%, even more preferably 0 to 0.3%, even more preferably 0.005 to 0.2%, and most preferably 0.01 to 0.1%, respectively.

MgO is a component of alkaline earth metal oxide that significantly increases Young's modulus. If the MgO content is too small, the melting property and Young's modulus tend to be lowered. Therefore, the lower limit amount of MgO is preferably 6%, more preferably 6.1%, more preferably 6.3%, more preferably 6.5%, more preferably 6.6%, more preferably 6.7%, more preferably 6.8%, and most preferably 7%. On the other hand, if the MgO content is too large, devitrified crystals such as mullite are likely to precipitate, and the liquid phase viscosity is likely to decrease. Therefore, the upper limit amount of MgO is preferably 12%, more preferably 11.8%, more preferably 11.5%, more preferably 11.3%, more preferably 11%, more preferably less than 11%, more preferably 10.8%, more preferably 10.6%, more preferably 10.4%, more preferably 10.2%, more preferably 10%, and most preferably 9.8%.

In order to improve Young's modulus and devitrification resistance, the molar percentage B ₂ O ₃ MgO is an important component ratio. If the mole% ratio B ₂ O ₃ If MgO is too small, devitrification resistance is lowered, and the production cost of the glass sheet tends to increase. Thus, mole% ratio B ₂ O ₃ The lower limit of MgO is preferably 0, more preferably 0.0001, further preferably 0.001, and most preferably 0.005. On the other hand, if the mole% ratio B ₂ O ₃ If MgO is too large, young's modulus tends to be lowered. Thus, mole% ratio B ₂ O ₃ The upper limit of the ratio of/MgO is preferably 0.2, more preferably 0.1, still more preferably 0.08Further preferably 0.05, further preferably 0.03, further preferably 0.02, and most preferably 0.01. "B" is a group of ₂ O ₃ MgO is the catalyst B ₂ O ₃ A value obtained by dividing the mol% content of MgO by the mol% content of MgO.

CaO is a component that reduces high-temperature tackiness without lowering strain point and significantly improves meltability. In addition, the Young's modulus is an ingredient for improving Young's modulus. When the CaO content is too small, the meltability tends to be lowered. Therefore, the lower limit amount of CaO is preferably 9%, more preferably more than 9%, more preferably 9.1%, more preferably 9.2%, more preferably 9.3%, more preferably 9.4%, more preferably 9.5%, more preferably 9.6%, and most preferably 10%. On the other hand, if the CaO content is too large, the liquid phase temperature becomes high. Therefore, the upper limit amount of CaO is preferably 13%, more preferably 12.9%, more preferably 12.8%, more preferably 12.6%, more preferably 12.5%, further preferably 12.4%, further preferably 12.2%, and most preferably 12%.

In order to improve the devitrification resistance, the mol% ratio MgO/CaO is an important component ratio. If the molar% ratio MgO/CaO is too small, the devitrification resistance tends to be lowered. Therefore, the lower limit of the mol% ratio MgO/CaO is preferably 0.6, more preferably 0.7, still more preferably 0.8, and most preferably 0.9. On the other hand, if the molar% ratio MgO/CaO is too large, the liquid phase viscosity is lowered, and the production cost of the glass plate tends to increase. Therefore, the upper limit of the mol% ratio MgO/CaO is preferably 2.0, more preferably 1.8, still more preferably 1.6, still more preferably 1.4, and most preferably 1.2. The "molar% ratio MgO/CaO" is a value obtained by dividing the mol% content of MgO by the mol% content of CaO.

SrO is not an essential component, but if SrO is contained, the effect of improving the devitrification resistance, further reducing the high-temperature viscosity without lowering the strain point, and improving the meltability can be obtained. In addition, the composition is a component for suppressing a decrease in the viscosity of the liquid phase. If the content of SrO is too small, the above effect is hardly obtained. Therefore, the lower limit amount of SrO is preferably 0%, more preferably more than 0%, more preferably 0.1%, more preferably more than 0.1%, more preferably 0.2%, more preferably 0.3%, more preferably more than 0.3%, more preferably 0.4%, more preferably more than 0.4%, and most preferably 0.5%. On the other hand, if the content of SrO is too large, the thermal expansion coefficient and density tend to increase. Therefore, the upper limit amount of SrO is preferably 2%, more preferably less than 2%, more preferably 1.8%, more preferably 1.6%, more preferably 1.5%, more preferably 1.4%, more preferably 1.2%, more preferably 1%, more preferably less than 1%, more preferably 0.9%, more preferably less than 0.9%, more preferably 0.8%, more preferably less than 0.8%, more preferably 0.7%, more preferably less than 0.7%, more preferably 0.6%, and most preferably less than 0.6%.

BaO is not an essential component, but if BaO is contained, the effect of improving the devitrification resistance can be obtained. Therefore, the lower limit amount of BaO is preferably 0%, more preferably more than 0%, more preferably 0.1%, more preferably more than 0.1%, more preferably 0.2%, more preferably 0.3%, more preferably 0.4%, more preferably more than 0.4%, and most preferably 0.5%. On the other hand, if the content of BaO is too large, the young's modulus tends to be low, and the density tends to be high. As a result, the glass plate is more likely to flex than the young's modulus is increased. Therefore, the upper limit amount of BaO is preferably 1%, more preferably less than 1%, more preferably 0.9%, further preferably less than 0.9%, further preferably 0.8%, further preferably less than 0.8%, and most preferably 0.7%.

SrO and BaO are components that improve resistance to devitrification. The lower limit amount of sro+bao is preferably 0%, more preferably more than 0%, more preferably 0.1%, more preferably more than 0.1%, more preferably 0.2%, more preferably 0.3%, more preferably 0.4%, more preferably more than 0.4%, and most preferably 0.5%. On the other hand, if the content of sro+bao is too large, the young's modulus tends to be low, and the density tends to be high. As a result, the glass plate is more likely to flex than the young's modulus is increased. Therefore, the upper limit amount of sro+bao is preferably 2%, more preferably less than 1%, more preferably 0.9%, further preferably less than 0.9%, further preferably 0.8%, further preferably less than 0.8%, and most preferably 0.7%. Herein, "sro+bao" means the total amount of SrO and BaO.

B ₂ O ₃ SrO and BaO are components for improving the devitrification resistance. B (B) ₂ O ₃ The lower limit amount of +sro+bao is preferably 0%, more preferably more than 0%, more preferably 0.1%, more preferably more than 0.1%, more preferably 0.2%, more preferably 0.3%, more preferably 0.4%, more preferably more than 0.4%, and most preferably 0.5%. On the other hand, if B ₂ O ₃ If the +SrO+BaO content is too large, young's modulus tends to be low. Thus B ₂ O ₃ The upper limit amount of +sro+bao is preferably 2%, more preferably less than 1%, more preferably 0.9%, further preferably less than 0.9%, further preferably 0.8%, further preferably less than 0.8%, and most preferably 0.7%. Here, "B ₂ O ₃ +SrO+BaO "means B ₂ O ₃ Total amount of SrO and BaO.

In order to achieve both Young's modulus and liquid phase viscosity, the molar ratio of SrO/SiO ₂ Is an important component ratio. If the mole percent ratio is SrO/SiO ₂ If the Young's modulus is too small, the Young's modulus tends to be low. Thus, mole% ratio of SrO/SiO ₂ The lower limit of (2) is preferably 0, more preferably more than 0, still more preferably 0.001, and most preferably more than 0.001. On the other hand, if the molar percentage is SrO/SiO ₂ If the viscosity of the liquid phase is too high, the production cost of the glass sheet tends to be high. Thus, mole% ratio of SrO/SiO ₂ The upper limit of (c) is preferably 0.03, more preferably 0.02, further preferably 0.015, further preferably 0.01, further preferably less than 0.01, further preferably 0.009, further preferably less than 0.009, further preferably 0.008, and most preferably less than 0.008.

In order to achieve both Young's modulus and meltability, the molar% ratio (MgO+CaO)/(MgO+CaO+SrO+BaO) is an important component ratio. If the molar ratio (mgo+cao)/(mgo+cao+sro+bao) is too small, the young's modulus and the meltability tend to be low. Therefore, the lower limit of the molar% ratio (mgo+cao)/(mgo+cao+sro+bao) is preferably 0.6, more preferably 0.7, further preferably 0.8, further preferably 0.9, and most preferably 0.95. On the other hand, if the molar ratio (mgo+cao)/(mgo+cao+sro+bao) is too large, the liquid phase viscosity decreases, and the manufacturing cost of the glass sheet tends to increase. Therefore, the upper limit of the molar% ratio (mgo+cao)/(mgo+cao+sro+bao) is preferably 1, more preferably 0.99, further preferably 0.98, and most preferably 0.97. The "molar% ratio (mgo+cao)/(mgo+cao+sro+bao)" is a value obtained by dividing the sum of the mol% contents of MgO and CaO by the sum of the mol% contents of MgO, caO, srO and BaO.

In order to improve Young's modulus and resistance to devitrification, the molar percentage (B ₂ O ₃ +SrO+BaO)/Al ₂ O ₃ Is an important component ratio. If the molar percentage (B) ₂ O ₃ +SrO+BaO)/Al ₂ O ₃ If the glass plate is too small, devitrification resistance is reduced, and the manufacturing cost of the glass plate tends to increase. Thus, the mole% ratio (B ₂ O ₃ +SrO+BaO)/Al ₂ O ₃ The lower limit of (c) is preferably 0.001, more preferably 0.005, more preferably 0.008, more preferably 0.01, more preferably 0.02, more preferably 0.03, more preferably 0.04, and most preferably 0.05. On the other hand, if the molar percentage (B ₂ O ₃ +SrO+BaO)/Al ₂ O ₃ If the Young's modulus is too large, the Young's modulus tends to be lowered. Thus, the mole% ratio (B ₂ O ₃ +SrO+BaO)/Al ₂ O ₃ The upper limit of (c) is preferably 0.3, more preferably 0.25, further preferably 0.2, further preferably 0.15, further preferably 0.12, further preferably 0.1, and most preferably 0.09.

In order to improve Young's modulus and resistance to devitrification, the molar percentage (B ₂ O ₃ +SrO+BaO)/MgO is an important component ratio. If the molar percentage (B) ₂ O ₃ When +SrO+BaO)/MgO is too small, devitrification resistance is reduced, and the production cost of the glass sheet tends to increase. Thus, the mole% ratio (B ₂ O ₃ The lower limit of +SrO+BaO)/MgO is preferably 0.001, more preferably 0.005, more preferably 0.008, more preferably 0.01, more preferably 0.02, more preferably 0.03, more preferably 0.04, and most preferably 0.05. On the other hand, if the molar percentage (B ₂ O ₃ If +SrO+BaO)/MgO is too large, young's modulus tends to be lowered. Because ofThe molar percentage (B) ₂ O ₃ The upper limit of +SrO+BaO)/MgO is preferably 0.5, more preferably 0.4, further preferably 0.3, further preferably 0.27, further preferably 0.24, further preferably 0.22, and most preferably 0.2. "(B) ₂ O ₃ +SrO+BaO)/MgO "means that B ₂ O ₃ The total mole% content of SrO and BaO divided by the mole% content of MgO.

The preferred content ranges of the respective components may be appropriately combined as a suitable glass composition range, and the glass composition is particularly preferably, in mol%, one containing: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～16％、B ₂ O ₃ 0 to less than 1 percent, li ₂ O+Na ₂ O+K ₂ 0 to 0.5 percent of O, 6 to 12 percent of MgO, 9 to 13 percent of CaO, more than 0 and less than 2 percent of SrO, 0 to 1 percent of BaO, and the mol percent of SrO/SiO ₂ 0 to 0.008.

In addition to the above components, for example, the following components may be added as optional components. The content of the other components than the above components is preferably 10% or less, particularly preferably 5% or less, based on the total amount, from the viewpoint of reliably obtaining the effects of the present invention.

P ₂ O ₅ Is a component for increasing the strain point and is a component capable of remarkably inhibiting devitrification and crystallization of alkaline earth aluminosilicate such as anorthite. However, if P is contained in a large amount ₂ O ₅ The glass is easily split. P (P) ₂ O ₅ The content of (2) is preferably 0 to 2.5%, more preferably 0 to 1.5%, even more preferably 0 to 0.5%, even more preferably 0 to 0.3%, and particularly preferably 0 to less than 0.1%.

TiO ₂ Is a component for reducing high-temperature viscosity and improving meltability and suppressing overexposure, but if a large amount of TiO is contained ₂ The glass is colored and the transmittance is easily lowered. TiO (titanium dioxide) ₂ The content of (2) is preferably 0 to 2.5%, more preferably 0.0005 to 1%, even more preferably 0.001 to 0.5%, particularly preferably 0.005 to 0.1%.

ZnO is a component for improving Young's modulus. However, when ZnO is contained in a large amount, the glass is liable to devitrify and the strain point is liable to decrease. The content of ZnO is preferably 0 to 6%, more preferably 0 to 5%, still more preferably 0 to 4%, particularly preferably 0.001 to less than 3%.

ZrO ₂ Is a component for improving Young's modulus. However, if ZrO is contained in a large amount ₂ The glass is easily devitrified. ZrO (ZrO) ₂ The content of (2) is preferably 0 to 2.5%, more preferably 0.0005 to 1%, even more preferably 0.001 to 0.5%, particularly preferably 0.005 to 0.1%.

Y ₂ O ₃ 、Nb ₂ O ₅ 、La ₂ O ₃ Has the effects of increasing strain point, young's modulus, etc. The total amount and the individual content of these components are preferably from 0 to 5%, more preferably from 0 to 1%, even more preferably from 0 to 0.5%, particularly preferably from 0 to less than 0.5%. If Y ₂ O ₃ 、Nb ₂ O ₅ 、L ₂ O ₃ If the total amount and the individual content of (b) are too large, the density and the raw material cost tend to increase.

SnO ₂ The composition has a good clarifying effect in a high temperature region, and is a composition for increasing a strain point, and is a composition for reducing high temperature tackiness. SnO (SnO) ₂ The content of (2) is preferably 0 to 1%, 0.001 to 1%, 0.01 to 0.5%, particularly preferably 0.05 to 0.3%. If SnO ₂ Is too high, snO ₂ The devitrified crystals of (a) are likely to precipitate. In addition, if SnO ₂ If the content of (2) is less than 0.001%, the above-mentioned effects are hardly obtained.

As described above, snO ₂ Suitable as a fining agent, but can be used as a fining agent instead of SnO as long as the glass properties are not impaired ₂ Or with SnO ₂ Together add F, SO ₃ The metal powders such as C, al, si, etc. are each at most 5% (preferably at most 1%, particularly preferably at most 0.5%). In addition, ceO as a clarifying agent ₂ F, etc. may also be added to each of at most 5% (preferably at most 1%, particularly preferably at most 0.5%).

As As clarifying agent ₂ O ₃ 、Sb ₂ O ₃ Is also effective. However, as ₂ O ₃ 、Sb ₂ O ₃ Is a component that increases environmental load. In addition, as ₂ O ₃ Is a component with reduced solarization resistance. Accordingly, the alkali-free glass sheet of the present invention preferably contains substantially no such components.

Cl is a component that promotes initial melting of the glass batch. In addition, if Cl is added, the action of the clarifier can be promoted. As a result, the melting cost can be reduced, and the life of the glass manufacturing furnace can be prolonged. However, if the Cl content is too large, the strain point tends to be lowered. Therefore, the Cl content is preferably 0 to 3%, more preferably 0.0005 to 1%, particularly preferably 0.001 to 0.5%. As the raw material for introducing Cl, a raw material such as a chloride of an alkaline earth metal oxide such as strontium chloride or aluminum chloride can be used.

Fe ₂ O ₃ The component is inevitably mixed from the glass raw material, and the component is also a component which reduces the resistivity. Fe (Fe) ₂ O ₃ The content of (2) is preferably 0 to 300 mass ppm, 80 to 250 mass ppm, particularly preferably 100 to 200 mass ppm. If Fe is ₂ O ₃ If the content of (2) is too small, the raw material cost tends to increase. On the other hand, fe ₂ O ₃ When the content of (b) is too large, the electric resistivity of the molten glass increases, and it is difficult to perform electric melting.

The alkali-free glass sheet of the present invention preferably has the following characteristics.

The average thermal expansion coefficient in the temperature range of 30 to 380 ℃ is preferably 30X 10 ^-7 /℃～50×10 ^-7 /℃、32×10 ^-7 /℃～48×10 ^-7 /℃、33×10 ^-7 /℃～45×10 ^-7 /℃、34×10 ^-7 /℃～44×10 ^-7 Per DEG C, in particular 35X 10 ^-7 /℃～43×10 ^-7 and/C. In this way, it is easy to match the thermal expansion coefficient of Si used in the TFT.

The Young's modulus is preferably 83GPa or more, more than 83GPa, 83.3GPa or more, 83.5GPa or more, 83.8GPa or more, 84GPa or more, 84.3GPa or more, 84.5GPa or more, 84.8GPa or more, 85GPa or more, 85.3GPa or more, 85.5GPa or more, 85.8GPa or more, 86GPa or more, particularly more than 86GPa and 120GPa or less. If the Young's modulus is too low, a problem is likely to occur due to the deflection of the glass plate.

The Young's modulus is preferably 32 GPa/g.cm ^-3 Above, 32.5 GPa/g.cm ^-3 Above, 33 GPa/g.cm ^-3 Above, 33.3 GPa/g.cm ^-3 Above, 33.5 GPa/g.cm ^-3 Above, 33.8 GPa/g.cm ^-3 Above 34 GPa/g.cm ^-3 Above, more than 34 GPa/g.cm ^-3 Above 34.2 GPa/g.cm ^-3 Above 34.4 GPa/g.cm ^-3 The above, in particular 34.5 to 37 GPa/g.cm ^-3 . If the Young's modulus is too low, a problem is likely to occur due to the deflection of the glass plate.

The strain point is preferably 730℃or higher, 732℃or higher, 734℃or higher, 735℃or higher, 736℃or higher, 738℃or higher, particularly 740 to 800 ℃. In this way, in the LTPS process, the thermal shrinkage of the glass sheet can be suppressed.

The liquid phase temperature is preferably 1350 ℃ or lower, 1300 ℃ or lower, 1290 ℃ or lower, 1285 ℃ or lower, 1280 ℃ or lower, 1275 ℃ or lower, 1270 ℃ or lower, particularly 1260 to 1200 ℃. Thus, devitrification crystals are easily prevented from occurring during glass production, and productivity is easily prevented from being lowered. Further, since the glass sheet is easily formed by the overflow down-draw method, the surface quality of the glass sheet is easily improved, and the manufacturing cost of the glass sheet can be reduced. The lower the liquid phase temperature is an index of the devitrification resistance, the more excellent the devitrification resistance is.

The liquid phase viscosity is preferably 10 ^4.0 dPa.s or more, 10 ^4.1 dPa.s or more, 10 ^4.2 dPa.s or more, especially 10 ^4.3 ～10 ^7.0 dPa.s. In this way, devitrification is less likely to occur during molding, and thus molding by the overflow downdraw method is easier, and as a result, the surface quality of the glass sheet can be improved, and the manufacturing cost of the glass sheet can be reduced. In addition, the higher the liquid phase viscosity is an index of devitrification resistance and formability, the higher the devitrification resistance and formability.

High temperature viscosity 10 ^2.5 The temperature at dPa.s is preferably1650 ℃ or lower, 1630 ℃ or lower, 1610 ℃ or lower, and particularly 1400 to 1600 ℃. If the high temperature viscosity is 10 ^2.5 If the temperature at dPa.s is too high, it is difficult to dissolve the glass batch, and the production cost of the glass sheet increases. The high-temperature viscosity 10 ^2.5 The temperature at dPa.s corresponds to the melting temperature, and the lower the temperature is, the higher the melting property is.

The β -OH value is an index indicating the amount of moisture in the glass, and if the β -OH value is lowered, the strain point can be raised. In addition, even when the glass composition is the same, the heat shrinkage at a temperature equal to or lower than the strain point becomes smaller for those having a small β -OH value. The β -OH number is preferably 0.35/mm or less, 0.30/mm or less, 0.28/mm or less, 0.25/mm or less, particularly preferably 0.20/mm or less. If the β -OH value is too small, the meltability tends to be low. Therefore, the β -OH value is preferably 0.01/mm or more, particularly preferably 0.03/mm or more.

As a method for reducing the β -OH value, the following method can be mentioned. (1) selecting a raw material with low water content. (2) Adding a component (Cl, SO) for reducing the beta-OH value to the glass ₃ Etc.). (3) reducing the amount of moisture in the furnace atmosphere. (4) N in molten glass ₂ Bubbling. (5) A small-sized melting furnace is used. (6) increasing the flow rate of the molten glass. (7) an electric melting method is used.

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

[ number 1]

beta-OH value= (1/X) log (T ₁ /T ₂ )

X: plate thickness (mm)

T ₁ : reference wavelength 3846cm ^-1 Transmittance at site (%)

T ₂ : hydroxyl absorption wavelength 3600cm ^-1 Minimum transmittance in the vicinity (%)

The alkali-free glass sheet of the present invention is preferably formed by an overflow downdraw process. The overflow downdraw method is a method of manufacturing a glass sheet by overflowing molten glass from both sides of a heat-resistant trough-like structure, joining the overflowed molten glass at the lower end of the trough-like structure, and performing downward extension molding. In the overflow downdraw method, the surface to be the surface of the glass sheet is formed in a free surface state without being in contact with the trough-like refractory. Therefore, a glass plate having excellent surface quality without polishing can be manufactured at low cost, and thinning is easy.

The alkali-free glass sheet of the present invention is also preferably formed by float forming. Large glass sheets can be manufactured at low cost.

The alkali-free glass sheet of the present invention preferably has a polished surface. When the glass surface is polished, the overall thickness deviation TTV can be reduced. As a result, the magnetic film can be formed appropriately, and thus is suitable for a substrate of a magnetic storage medium.

In the alkali-free glass plate of the present invention, the plate thickness is not particularly limited, but in the case of being used for an organic EL device, the plate thickness is preferably less than 0.7mm, 0.6mm or less, less than 0.6mm, and particularly preferably 0.05 to 0.5mm. The thinner the plate thickness is, the lighter the organic EL device can be. The sheet thickness can be adjusted by the flow rate, the drawing speed, and the like at the time of glass production. On the other hand, when used in a magnetic storage medium, the thickness of the sheet is preferably 1.5mm or less, 1.2mm or less, 0.2 to 1.0mm, particularly 0.3 to 0.9mm. If the plate thickness is too large, the plate must be etched to a desired plate thickness, and the processing cost may increase.

The alkali-free glass plate of the present invention is preferably used for substrates of organic EL devices, particularly display panels for organic EL televisions, and carriers for manufacturing organic EL display panels. In particular, in the application of organic EL television, a plurality of devices are manufactured on a glass plate, and then each device is cut apart and cut, thereby realizing cost reduction (so-called multi-piece splicing). The alkali-free glass sheet of the present invention can be easily formed into a large glass sheet, and thus can reliably satisfy such a demand.

The alkali-free glass plate of the present invention is excellent in productivity and has a sufficiently high strain point and young's modulus, and therefore is preferably used for a substrate of a magnetic storage medium, particularly an energy-assisted magnetic storage medium. In order to increase the degree of ordering (degree of ordering) of the magnetic layer, the substrate including the glass plate is heat-treated at a high temperature of about 800 ℃ during or before forming the magnetic layer, and the impact on the substrate accompanied by high-speed rotation of the magnetic storage medium is also tolerated. The alkali-free glass plate of the present invention is processed into a disk substrate 1 shown in fig. 1 by cutting or the like. In the case of such a substrate for a magnetic storage medium, the disk substrate 1 preferably has a disk shape, and more preferably has a circular opening C formed in the center.

Examples

The present invention will be described below based on examples. The following examples are merely illustrative. The present invention is not limited in any way by the following examples.

Tables 1 to 3 show examples (sample nos. 1 to 30) of the present invention.

TABLE 1

TABLE 2

TABLE 3

First, a glass batch obtained by blending glass raw materials was put into a platinum crucible so as to have a glass composition as shown in the table, and melted at 1600 to 1650 ℃ for 24 hours. During dissolution of the glass batch, homogenization was performed by stirring with a platinum stirrer. Then, the molten glass was flowed out onto a carbon plate to be formed into a plate shape, and then annealed at a temperature near the annealing point for 30 minutes. For each sample obtained, the average coefficient of thermal expansion CTE, density ρ, young's modulus E, specific Young's modulus E/ρ, strain point Ps, annealing point Ta, softening point Ts, high temperature viscosity 10 were evaluated in the temperature range of 30 to 380 ℃ ⁴ Temperature at dPa.s, viscosity at high temperature 10 ³ Temperature at dPa.s, viscosity at high temperature 10 ^2.5 Temperature at dPa.s, liquidus temperature TL, and viscosity log10 ηTL at liquidus temperature TL.

The average coefficient of thermal expansion CTE in the temperature range of 30 to 380 ℃ is a value measured with an dilatometer.

The density ρ is a value measured by a known archimedes method.

Young's modulus E is a value measured by a known resonance method.

The specific Young's modulus E/ρ is a value obtained by dividing Young's modulus by density.

The strain point Ps, the annealing point Ta, and the softening point Ts are values measured by the methods according to ASTM C336 and C338.

High temperature viscosity 10 ⁴ dPa·s、10 ³ dPa·s、10 ^2.5 The temperature at dPa.s is a value measured by a platinum ball pulling method.

The liquidus temperature TL is a temperature at which crystals are precipitated after placing glass powder passing through a standard sieve of 30 mesh (500 μm) and remaining at 50 mesh (300 μm) in a platinum boat and holding the glass powder in a temperature gradient furnace for 24 hours.

The liquid phase viscosity log10 ηtl is a value obtained by measuring the glass viscosity at the liquid phase temperature TL by the platinum ball pulling method.

As is clear from tables 1 to 3, since the glass compositions of sample Nos. 1 to 30 are limited to the predetermined ranges, the Young's modulus is 88GPa or more, the strain point is 738℃or more, the liquid phase temperature is 1300℃or less, and the liquid phase viscosity is 10 ^4.0 dPa.s or more. Therefore, sample nos. 1 to 30 are excellent in productivity, and have sufficiently high strain points and young's modulus, and thus are suitable for substrates of organic EL devices and magnetic storage media.

Industrial applicability

The alkali-free glass plate of the present invention is suitable as a substrate for an organic EL device, particularly a display panel for an organic EL television, a carrier for manufacturing an organic EL display panel, a flat panel display substrate such as a liquid crystal display, a protective glass for an image sensor such as a Charge Coupled Device (CCD) or a solid state imaging device (CIS), a substrate for a solar cell, a protective glass, a substrate for an organic EL illumination, and the like.

The alkali-free glass plate of the present invention is also suitable as a substrate for a magnetic storage medium because of its sufficiently high strain point and young's modulus. If the strain point is high, deformation of the glass plate is less likely to occur even when heat treatment or laser irradiation is performed at a high temperature such as heat assist. As a result, when the Ku is increased, a higher heat treatment temperature can be used, and therefore, a magnetic memory device with a high memory density can be easily manufactured. In addition, if the young's modulus is high, the glass plate is less likely to flex or shake (tremble) during high-speed rotation, and therefore collision between the information storage medium and the magnetic head can be prevented.

Claims (11)

1. An alkali-free glass plate is characterized in that,

the glass composition contains, in mol%: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～16％、B ₂ O ₃ 0～3％、Li ₂ O+Na ₂ O+K ₂ 0 to 0.5 percent of O, 6 to 12 percent of MgO, 9 to 13 percent of CaO, 0 to 2 percent of SrO and 0 to 1 percent of BaO, and the mol percent ratio is SrO/SiO ₂ 0 to 0.03.

2. An alkali-free glass sheet according to claim 1, wherein,

the glass composition contains, in mol%: siO (SiO) ₂ 64～72％、Al ₂ O ₃ 12～16％、B ₂ O ₃ 0 to less than 1 percent, li ₂ O+Na ₂ O+K ₂ 0 to 0.5 percent of O, 6 to 12 percent of MgO, 9 to 13 percent of CaO, more than 0 and less than 2 percent of SrO, 0 to 1 percent of BaO, and the mol percent ratio of SrO/SiO ₂ 0 to 0.008.

3. Alkali-free glass sheet according to claim 1 or 2, characterized in that,

the glass composition is substantially free of As ₂ O ₃ 、Sb ₂ O ₃ 。

4. An alkali-free glass sheet according to any of claims 1 to 3,

the alkali-free glass plate also contains 0.001mol% to 1mol% of SnO ₂ 。

5. An alkali-free glass sheet according to any of claims 1 to 4,

the alkali-free glass plate has a Young's modulus of 83GPa or more, a strain point of 730 ℃ or more, and a liquid phase temperature of 1350 ℃ or less.

6. An alkali-free glass sheet according to any of claims 1 to 5,

the strain point of the alkali-free glass plate is over 735 ℃.

7. An alkali-free glass sheet according to any of claims 1 to 6,

the Young's modulus of the alkali-free glass sheet is higher than 84GPa.

8. An alkali-free glass sheet according to any of claims 1 to 7,

the average thermal expansion coefficient of the alkali-free glass plate in the temperature range of 30-380 ℃ is 30 multiplied by 10 ^-7 ～50×10 ^-7 /℃。

9. An alkali-free glass sheet according to any of claims 1 to 8,

the liquid phase viscosity of the alkali-free glass plate is 10 ^4.0 dPa.s or more.

10. Alkali-free glass sheet according to any of claims 1 to 9, characterized in that,

the alkali-free glass sheet is used for organic EL devices.

11. Alkali-free glass sheet according to any of claims 1 to 9, characterized in that,

the alkali-free glass sheet is used in magnetic storage media.