WO2019150930A1

WO2019150930A1 - Glass

Info

Publication number: WO2019150930A1
Application number: PCT/JP2019/000856
Authority: WO
Inventors: 敦己斉藤
Original assignee: 日本電気硝子株式会社
Priority date: 2018-01-31
Filing date: 2019-01-15
Publication date: 2019-08-08
Also published as: JP2019131429A; TWI798332B; TW201934510A; JP7418947B2; JP2022105215A; TW202330418A; CN111164056A

Abstract

A glass according to the present invention is characterized by having a glass composition that contains 67-73 mol% of SiO₂, 10-15 mol% of Al₂O₃, 0-3 (exclusive of 3) mol% of B₂O₃, 0-0.5 mol% of Li₂O+Na₂O+K₂O, 0-8.5 mol% of MgO, 3.5-12mol% of CaO, 0-2.5mol% of SrO, and 1-6mol% of BaO, wherein a value obtained by dividing a strain point (°C) by the content (mol%) of Al₂O₃ is 51 or more.

Description

Glass

The present invention relates to glass, and more particularly, to a glass suitable for a carrier glass or the like used when producing an organic EL element on a substrate of an organic EL display or a polyimide substrate.

Electronic devices such as organic EL displays are thin and excellent in moving picture display and have low power consumption, so they are used for mobile phone displays and the like. In addition, organic EL displays using a polyimide substrate are lightweight and flexible, and therefore are being applied to various displays.

Glass plates are widely used as substrates for organic EL displays. And the glass plate is also used for the carrier glass used when producing an organic EL element on a polyimide substrate. The following characteristics are mainly required for glass plates for these applications.
(1) The content of the alkali metal oxide is small in order to prevent a situation where alkali ions are diffused in the semiconductor material formed in the heat treatment step.
(2) In order to reduce the cost of the glass plate, it is excellent in productivity, particularly excellent in devitrification resistance and meltability.
(3) In the manufacturing process of p-Si • TFT, the strain point is high in order to reduce the amount of heat shrinkage.

Special table 2009-525942

The required characteristic (3) will be described in detail. There is a heat treatment step of 400 to 600 ° C. in the film formation process of the p-Si • TFT, and a minute dimensional change called heat shrinkage occurs in this heat treatment step. . When the amount of heat shrinkage is large, the pixel pitch of the TFT is displaced, which causes display defects. In the case of an organic EL display, there is a possibility that a display defect may occur even if the dimensional shrinkage is about several ppm. In addition, thermal contraction becomes large, so that the heat processing temperature which a glass plate receives is high.

Further, even in the case of a carrier glass used when producing an organic EL element on a polyimide substrate, it goes through a heat treatment step at the same temperature as when producing the organic EL element on a glass plate. If the amount of heat shrinkage of the glass plate is large, the heat shrinkage is transmitted to the polyimide substrate, thereby causing a shift in the pixel pitch.

As can be seen from the above, in these applications, glass plates that are difficult to heat shrink are advantageous. As a method for reducing the amount of heat shrinkage, there is a method of performing an annealing treatment in the vicinity of an annealing point after forming a glass plate. However, since the annealing process takes a long time, the manufacturing cost of the glass plate increases.

Another method is to increase the strain point of the glass plate. As the strain point is higher, thermal shrinkage is less likely to occur in the manufacturing process of the p-Si • TFT. For example, Patent Document 1 discloses a glass plate having a high strain point.

However, a glass with a high strain point generally contains a large amount of hardly soluble SiO ₂ or Al ₂ O ₃ , and therefore has low devitrification resistance and meltability (particularly batch solubility), and is inexpensive and high quality glass. Is difficult to produce stably. Therefore, it is difficult for the glass with a high strain point to satisfy the required property (2).

The present invention has been made in view of the above circumstances, and its technical problem is to create a glass that has a small amount of thermal shrinkage in the manufacturing process of p-Si • TFT and has high devitrification resistance and high melting property. It is.

As a result of repeating various experiments, the present inventor has found that the above technical problem can be solved by strictly regulating the glass composition of low alkali glass and the relationship between Al ₂ O ₃ and strain point. This is proposed as the present invention. That is, the glass of the present invention has a glass composition of mol%, SiO ₂ 67-73%, Al ₂ O ₃ 10-15%, B ₂ O ₃ 0-3%, Li ₂ O + Na ₂ O + K ₂ O 0 0.5%, MgO 0-8.5%, CaO 3.5-12%, SrO 0-2.5%, BaO 1-6%, and the strain point (° C.) of Al ₂ O ₃ The value divided by the content (mol%) is 51 or more. Here, “Li ₂ O + Na ₂ O + K ₂ O” refers to the total amount of Li ₂ O, Na ₂ O and K ₂ O. “Strain point” refers to a value measured based on the method of ASTM C336.

The glass of the present invention has a glass composition of mol%, SiO ₂ 67-73%, Al ₂ O ₃ 10-15%, B ₂ O ₃ 0-1.3%, Li ₂ O + Na ₂ O + K ₂ O. Contains 0 to 0.5%, MgO 0 to 3.2%, CaO 3.5 to 12%, SrO 0 to 2%, BaO 3.5 to 6%, and CaO- (SrO + BaO) 3.1% As described above, the molar ratio CaO / Al ₂ O ₃ is 1.05 or less, and the molar ratio SrO / BaO is 0.03 to 0.50. Here, “CaO− (SrO + BaO)” refers to a value obtained by subtracting the total amount of SrO and BaO from the content of CaO. “CaO / Al ₂ O ₃ ” refers to a value obtained by dividing the content of CaO by the content of Al ₂ O ₃ . “SrO / BaO” refers to a value obtained by dividing the content of SrO by the content of BaO.

The glass of the present invention has a glass composition of mol%, SiO ₂ 67 to 73%, Al ₂ O ₃ 12 to 15%, B ₂ O ₃ 0 to less than 1.8%, Li ₂ O + Na ₂ O + K _2. O 0 to less than 0.5%, MgO 0 to 6%, CaO 5% or more, SrO 0 to 2%, BaO 3.5% or more, CaO- (SrO + BaO) 0.7% or more, molar ratio SrO / BaO is 0.38 or less, molar ratio (MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 1.09 to 1.70, and the value obtained by dividing the strain point (° C.) by the content (mol%) of Al ₂ O ₃ 55 or more. Here, “(MgO + CaO + SrO + BaO) / Al ₂ O ₃ ” refers to a value obtained by dividing the total amount of MgO, CaO, SrO, and BaO by the content of Al ₂ O ₃ .

The glass of the present invention has a glass composition of mol%, SiO ₂ 67-73%, Al ₂ O ₃ 10-15%, B ₂ O ₃ 0-3%, Li ₂ O + Na ₂ O + K ₂ O 0-0 It is preferable to contain 0.5%, MgO 0 to 8.5%, CaO 3.5 to 12%, SrO 0 to 2.5%, BaO 1 to 6%. The reason for defining the content range of each component as described above is shown below. In the description of the content range of each component, “%” means “mol%” unless otherwise specified.

SiO ₂ is a component that forms a glass skeleton and increases the strain point. Furthermore, it is a component that enhances chemical resistance such as hydrochloric acid. On the other hand, when the amount of SiO ₂ increases, the meltability is remarkably lowered or the HF etching rate is lowered. Therefore, the preferable lower limit range of SiO ₂ is 67% or more, 68% or more, 69% or more, particularly 70% or more, and the preferable upper limit range is 73% or less, particularly 72% or less.

Al ₂ O ₃ is a component that increases the strain point and Young's modulus. On the other hand, when Al ₂ O ₃ is increased, batch solubility at the time of initial melting is lowered, and a molding temperature is increased. The preferred lower limit range of Al ₂ O ₃ is 10% or more, 11% or more, particularly 12% or more, and the preferred upper limit range is 15% or less, 14% or less, 13% or less, particularly 12.5% or less. . In addition, when a small amount of B ₂ O ₃ is introduced to lower the meltability and molding viscosity, a relatively large amount of Al ₂ O ₃ can be introduced into the glass composition. On the other hand, when almost no B ₂ O ₃ is contained, too much Al ₂ O ₃ cannot be introduced into the glass composition. In that case, the content of Al ₂ O ₃ is preferably as small as possible.

B ₂ O ₃ is a component that improves the meltability and devitrification resistance, and is a component that lowers the molding temperature. On the other hand, when a large amount of B ₂ O ₃ is introduced, the strain point and Young's modulus also decrease. The content of B ₂ O ₃ is preferably less than 3%, 2.5% or less, 2% or less, less than 1.8%, 1.3% or less, particularly 0.8% or less.

Although the details will be described later, the introduction raw material of B ₂ O ₃ is a source of a lot of moisture in the glass. Therefore, the content of B ₂ O ₃ is preferably as small as possible from the viewpoint of reducing moisture. Furthermore, when producing a glass plate by complete electric melting without using combustion, the smaller the content of B ₂ O ₃ , the easier the glass batch to spread uniformly in the melting furnace, thereby improving the homogeneity of the molten glass. Can do.

Li ₂ O, Na ₂ O, and K ₂ O are components that increase the meltability and decrease the electrical resistivity of the molten glass, but when Li ₂ O, Na ₂ O, and K ₂ O increase, alkali ions The diffusion of the semiconductor material may cause contamination of the semiconductor material. Therefore, the total amount of Li ₂ O, Na ₂ O and K ₂ O is preferably 0 to 0.5%, 0 to less than 0.5%, 0.01 to 0.3%, 0.02 to 0.00. 2%, especially 0.03 to less than 0.1%. The content of Na ₂ O is preferably 0 to 0.3%, 0.01 to 0.3%, 0.02 to 0.2%, particularly 0.03 to less than 0.1%. The content of K ₂ O is preferably 0 to 0.3%, 0 to 0.2%, in particular 0 to less than 0.1%.

MgO is a component that increases meltability and Young's modulus. On the other hand, MgO is a component that lowers the strain point. When reducing the amount of Al ₂ O _{3 in} order to reduce the melting temperature and the molding temperature, it is necessary to introduce a large amount of SiO ₂ in order to maintain a high strain point. When a large amount of MgO is introduced in such a composition region containing a large amount of SiO ₂ , cristobalite is likely to precipitate during molding, and the strain point is likely to be lowered. Therefore, in this case, the content of MgO is preferably as low as possible. The content of MgO is preferably 0 to 8.5%, 0 to 6%, 0 to 5%, 0 to 3.2%, 0 to 3%, especially 0 to 1%. In addition, when a small amount of B ₂ O ₃ is introduced in order to lower the melting temperature and the molding temperature, the content of SiO ₂ can be relatively small, and the content of Al ₂ O ₃ can be relatively large. . In this case, it is preferable to positively introduce MgO, and the content of MgO is preferably 1 to 8.5%, 2 to 6%, particularly 2.5 to 5%.

CaO is a component that enhances meltability and batch solubility. CaO is a component that lowers the raw material cost because the introduced raw material is relatively inexpensive among alkaline earth metal oxides. Moreover, it is a component which suppresses precipitation of the devitrification crystal | crystallization containing Mg. On the other hand, when CaO increases, feldspar-based devitrification crystals (for example, anorthite) containing Ca are likely to precipitate during molding. Therefore, the content of CaO is preferably 3.5 to 12%, 4 to 11%, 5 to 11%, particularly 5.5 to 11%.

SrO is a component that makes cristobalite difficult to precipitate during molding, and a component that lowers the melting temperature without significantly reducing the strain point. On the other hand, when SrO increases, the density increases and the Young's modulus tends to decrease. Further, in a composition region where anorthite tends to precipitate as the initial phase, when SrO increases, the liquidus temperature decreases, and the productivity of the glass plate tends to decrease. Therefore, the content of SrO is preferably 0 to 2.5%, 0 to 2%, particularly 0.1 to 1.3%.

BaO is a component that suppresses precipitation of devitrified crystals such as mullite and anorthite containing Al during molding in alkaline earth metal oxides. On the other hand, when BaO increases, the density increases and the Young's modulus tends to decrease. The preferred lower limit range of BaO is 1% or more, 2% or more, 3% or more, particularly 3.5% or more, and the preferred upper limit range is 12% or less, 11% or less, 10% or less, 8% or less, particularly 6% or less.

Alkaline earth metal oxides are very important components for enhancing the strain point, devitrification resistance and meltability. When the amount of alkaline earth metal oxide is small, the strain point increases, but Al ₂ O ₃ -based devitrified crystals are likely to precipitate during molding, and the high-temperature viscosity becomes high, so that the meltability is likely to decrease. Therefore, the ratio of the total content of the alkaline earth metal oxide (MgO + CaO + SrO + BaO) and the content of Al ₂ O ₃ becomes very important. Specifically, when the molar ratio (MgO + CaO + SrO + BaO) / Al ₂ O ₃ increases, the meltability and formability are improved, but the strain point tends to decrease. Conversely, when this value decreases, the strain point increases. The meltability and moldability tend to be reduced. Therefore, the preferable lower limit range of the molar ratio (MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 0.95 or more, 1.00 or more, 1.05 or more, particularly 1.09 or more, and the preferable upper limit range is 1.70 or less. .

The molar ratio CaO / Al ₂ O ₃ is one of important indicators for maintaining a high strain point while ensuring meltability. In a composition region containing a large amount of CaO, it is important to design the composition so that the strain point does not decrease. Then, _Al 2 _{O 3} is in the alkaline earth aluminosilicate glass which is a main component to increase the strain point other than SiO _2. From these viewpoints, the molar ratio CaO / Al ₂ O ₂ is preferably 1.09 or less, 1.07 or less, 1.05 or less, particularly 0.25 to 1.05.

In order to produce a glass with a high strain point while reducing the production load, the blending ratio of the four components of the alkaline earth metal oxide is very important. From this point of view, CaO- (SrO + BaO) is preferably -3% or more, -1% or more, 0% or more, 0.7% or more, 2% or more, particularly 3.1 to 15%. When the amount of CaO- (SrO + BaO) increases, the melting temperature and the molding temperature decrease, and the productivity of the glass plate can be increased.

In the composition region containing a large amount of CaO, it is important from the viewpoint of devitrification resistance to regulate the molar ratio SrO / BaO. Specifically, in the composition region containing a large amount of CaO, anorthite tends to precipitate as the initial phase as described above. Among alkaline earth metal oxides, SrO is a component that raises the liquid phase temperature of anorthite, and BaO is a component that lowers the liquidus temperature of anorthite. Therefore, the smaller the molar ratio SrO / BaO, the lower the liquid phase temperature of anorthite. However, if SrO is not introduced at all, devitrifying crystals such as cristobalite are likely to precipitate during molding. In view of the above points, the preferred lower limit range of the molar ratio SrO / BaO is 0 or more, particularly 0.03 or more, and the preferred upper limit range is 0.70 or less, 0.63 or less, 0.50 or less, particularly 0.38 or less.

In addition to the above components, for example, the following components may be introduced.

ZnO is a component that enhances the meltability. However, when the amount of ZnO increases, the glass tends to devitrify and the strain point tends to decrease. Therefore, the content of ZnO is preferably 0 to 5%, 0 to 3%, 0 to 0.5%, particularly 0 to 0.2%.

P ₂ O ₅ is a component that lowers the liquidus temperature of the Al-based devitrified crystal. However, when P ₂ O ₅ increases, the strain point decreases, and cristobalite is likely to precipitate during molding. Therefore, the content of P ₂ O ₅ is preferably 0 to 1.5%, 0 to 1.2%, particularly 0 to less than 0.1%.

TiO ₂ is a component that lowers the high-temperature viscosity and increases the meltability, and also suppresses solarization. However, when the amount of TiO ₂ increases, the glass is colored and the transmittance tends to decrease. Therefore, the content of TiO ₂ is preferably 0 to 5%, 0 to 3%, 0 to 1%, 0 to 0.1%, particularly 0 to 0.02%.

ZrO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ , and La ₂ O ₃ have a function of increasing the strain point, Young's modulus, and the like. However, when these components increase, the density tends to increase. Therefore, the contents of ZrO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ and La ₂ O ₃ are 0 to 5%, 0 to 3%, 0 to 1%, 0 to less than 0.1%, particularly 0 It is preferably less than 0.05%. Furthermore, the total amount of Y ₂ O ₃ and La ₂ O ₃ is preferably less than 0.1%.

SnO ₂ is a component that has a good clarification action in a high temperature range, a component that increases the strain point, and a component that decreases high temperature viscosity. The content of SnO ₂ is preferably 0 to 1%, 0.001 to 1%, 0.01 to 0.5%, particularly 0.05 to 0.3%. When SnO ₂ increases, SnO ₂ devitrified crystals are likely to precipitate during molding.

As long as the glass properties are not impaired, metal powder such as F ₂ , Cl ₂ , SO ₃ , C, Al, Si or the like can be added up to 2% as a fining agent. Further, it can be added as a refining agent, also CeO _2, etc. up to 1%.

As ₂ O ₃ and Sb ₂ O ₃ are effective as fining agents, and the glass of the present invention does not completely eliminate the introduction of these components, but these components are used as much as possible from an environmental point of view. Preferably not. Further, as As ₂ O ₃ increases, the solarization resistance tends to decrease. Therefore, the content is preferably 0.1% or less, and it is desirable that the content is not substantially contained. Here, “substantially does not contain As ₂ O ₃ ” refers to the case where the content of As ₂ O ₃ in the glass composition is less than 0.05%. Further, the content of Sb ₂ O ₃ is preferably 0.2% or less, particularly preferably 0.1% or less, and it is desirable that the Sb ₂ O ₃ content is not substantially contained. Here, “substantially does not contain Sb ₂ O ₃ ” refers to a case where the content of Sb ₂ O ₃ in the glass composition is less than 0.05%.

Fe ₂ O ₃ is a component that lowers the electrical resistivity of the molten glass. The content of Fe ₂ O ₃ is preferably 0 to 0.2%, 0.001 to 0.1%, 0.005 to 0.05%, particularly 0.008 to 0.015%. When the content of Fe ₂ O ₃ is small, it becomes difficult to enjoy the effect of the above. On the other hand, when Fe ₂ O ₃ increases, the transmittance in the ultraviolet region tends to decrease, and the irradiation efficiency when using a laser in the ultraviolet region in the manufacturing process of the display tends to decrease. In addition, when performing electric melting, it is preferable to introduce Fe ₂ O ₃ positively, and in that case, the content of Fe ₂ O ₃ is 0.005 to 0.03%, 0.008 to 0.025%. In particular, 0.01 to 0.02% is preferable. Further, when it is desired to increase the transmittance in the ultraviolet region, the content of Fe ₂ O ₃ is preferably 0.020% or less, 0.015% or less, 0.011% or less, particularly 0.010% or less. .

Further, in relation to Fe ₂ O ₃ , the MgO raw material becomes the main mixing source of Fe ₂ O ₃ . Therefore, from the viewpoint of increasing the transmittance in the ultraviolet region, it is preferable to reduce the content of MgO as much as possible.

Cl has an effect of promoting the melting of the low alkali glass. If Cl is added, the melting temperature can be lowered and the action of the fining agent can be promoted. Further, Cl has an effect of lowering the β-OH value of the molten glass. However, when Cl increases, the strain point decreases and the environmental load increases. Therefore, the Cl content is preferably 0.5% or less, particularly 0.001 to 0.2%. In addition, as a raw material for introducing Cl, a raw material such as an alkaline earth metal oxide chloride such as strontium chloride or aluminum chloride can be used.

The glass of the present invention preferably has the following characteristics.

The strain point is preferably 730 ° C. or higher, 735 ° C. or higher, 740 ° C. or higher, particularly 745 ° C. or higher. If the strain point is low, the glass plate is likely to be thermally contracted in the manufacturing process of the p-Si • TFT.

In order to obtain a glass having a small amount of thermal shrinkage and high meltability in the manufacturing process of p-Si • TFT, it is important to simultaneously improve the strain point and batch solubility. On the other hand, Al ₂ O ₃ is a component that greatly reduces batch solubility. Therefore, it is important from the above viewpoint to increase the value obtained by dividing the strain point (° C.) by the content (mol%) of Al ₂ O ₃ , and the strain point (° C.) is changed to the content (mol) of Al ₂ O _3. %) Is preferably 51 or more, 53 or more, in particular 55 to 80.

The density is preferably 2.71 g / cm ³ or less, 2.69 g / cm ³ or less, 2.67 g / cm ³ or less, particularly 2.64 g / cm ³ or less. When the density is high, the specific Young's modulus increases, the glass plate is easily bent by its own weight, and when used for a substrate, the mass of the organic EL display increases.

歪 Lowering the β-OH value can increase the strain point. The β-OH value is preferably 0.30 / mm or less, 0.25 / mm or less, 0.20 / mm or less, 0.15 / mm or less, particularly 0.10 / mm or less. As the β-OH value increases, the strain point tends to decrease. If the β-OH value is excessively small, Cl in the glass may become excessive. Therefore, the β-OH value is preferably 0.01 / mm or more, particularly 0.02 / mm or more.

As a method for reducing the β-OH value, the following methods may be mentioned. (1) A glass material having a low moisture content is selected. (2) Add a component (Cl, SO ₃ or the like) that reduces the amount of moisture in the glass. (3) Reduce the amount of moisture in the furnace atmosphere. (4) N ₂ bubbling is performed in molten glass. (5) Adopt a small melting furnace. (6) Increase the flow rate of the molten glass. (7) An electric melting method is adopted.

Here, “β-OH value” refers to a value obtained by measuring the transmittance of glass using FT-IR and using the following equation.
β-OH value = (1 / X) log (T ₁ / T ₂ )
X: Glass wall thickness (mm)
T ₁ : Transmittance (%) at a reference wavelength of 3846 cm ⁻¹
T ₂ : Minimum transmittance (%) in the vicinity of a hydroxyl group absorption wavelength of 3600 cm ⁻¹

The liquidus temperature is preferably less than 1320 ° C, 1300 ° C or less, 1280 ° C or less, 1260 ° C or less, 1240 ° C or less, particularly 1220 ° C or less. When the liquidus temperature is high, devitrified crystals are precipitated during forming by the overflow down draw method or the like, and the productivity of the glass plate is lowered. The “liquid phase temperature” is obtained by passing the standard sieve 30 mesh (mesh opening 500 μm) and putting the glass powder remaining in 50 mesh (mesh opening 300 μm) in a platinum boat and keeping it in a temperature gradient furnace for 24 hours. The temperature at which the crystal (primary phase) precipitates is measured.

The liquid phase viscosity is preferably 10 ^4.5 dPa · s or more, 10 ^4.8 dPa · s or more, 10 ^5.0 dPa · s or more, 10 ^5.2 dPa · s or more, particularly 10 ^5.3 dPa · s or more. s or more. When the liquid phase viscosity is low, devitrified crystals are deposited during forming by the overflow down draw method or the like, and the productivity of the glass plate is lowered. The “liquid phase viscosity” refers to a value obtained by measuring the viscosity of glass at the liquid phase temperature by a platinum ball pulling method.

The temperature at a high temperature viscosity of 10 ^4.5 dPa · s is preferably less than 1320 ° C., 1310 ° C. or less, 1305 ° C. or less, particularly 1300 ° C. or less. The temperature at a high temperature viscosity of 10 ^4.5 dPa · s corresponds to the molding temperature in the case of molding by the overflow downdraw method. When the molding temperature becomes high, the molded body tends to undergo creep deformation, and a high-quality glass plate cannot be produced stably. Although it is possible to produce a glass plate by exchanging one that has undergone creep deformation, since the molded body is very expensive, the manufacturing cost of the glass plate increases. The “temperature at a high temperature viscosity of 10 ^4.5 dPa · s” can be measured by a platinum ball pulling method.

When the temperature at a high temperature viscosity of 10 ^2.5 dPa · s is η _2.5 and the temperature at a high temperature viscosity of 10 ^4.0 dPa · s is η _4.0 , (η _2.5 −η _4.0 ) / η _2.5 is preferably 0.158 or more, 0.163 or more, particularly 0.170 or more. The temperature at a high temperature viscosity of 10 ^2.5 dPa · s is generally an indicator of meltability, and the lower this temperature, the higher the meltability. However, if a composition is designed in pursuit of a high strain point as in the present invention, the temperature at a high temperature viscosity of 10 ^2.5 dPa · s inevitably increases. And when using a heat-resistant metal such as platinum in a clarification container (clarification pipe), with such a high melting point glass, the temperature of the clarification container (clarification pipe) can be raised from the heat resistance limit of platinum to a temperature sufficient for clarification. It becomes difficult. However, even in such a case, if the temperature change with respect to the viscosity change in the vicinity of the temperature at a high temperature viscosity of 10 ^2.5 dPa · s is large, the process window becomes wide, which is advantageous in improving the foam quality. . “(Η _2.5 −η _4.0 ) / η _2.5 ” means a temperature obtained by subtracting the temperature at the high temperature viscosity of 10 ^4.0 dPa · s from the temperature at the high temperature viscosity of 10 ^2.5 dPa · s. It is a value divided by the temperature at a high temperature viscosity of 10 ^2.5 dPa · s. The “temperature at high temperature viscosity of 10 ^2.5 dPa · s” and “temperature at high temperature viscosity of 10 ^4.0 dPa · s” can be measured by the platinum ball pulling method.

Specific modulus is preferably 29.5GPa / g · ^{cm -3} or more, 29.7GPa / g · ^{cm -3} or more, 30GPa / g · ^{cm -3} or more, 31GPa / g · ^{cm -3} or more, 31.5GPa / G · cm ⁻³ or more, particularly 32 GPa / g · cm ⁻³ or more. When the specific Young's modulus is low, the glass plate is easily bent by its own weight, and the glass plate is easily damaged during the p-Si · TFT film forming process. “Specific Young's modulus” is a value obtained by dividing Young's modulus by density. The “Young's modulus” can be measured by a known resonance method.

The etching rate by HF is preferably 0.8 μm / min or more, 0.9 μm / min or more, particularly 1.0 μm / min or more. When a glass plate is used for a substrate of a mobile terminal or the like, the glass plate is thinned by hydrofluoric acid (HF) etching. If the etching rate by HF is low, slimming takes time, which causes an increase in cost. Here, the “HF etching rate” refers to an etching depth when a mirror-polished glass surface is etched with a 10 mass% HF aqueous solution at 20 ° C. for 30 minutes.

The glass of the present invention has a flat plate shape and preferably has an overflow merging surface at the center in the thickness direction. That is, it is preferably formed by an overflow downdraw method. The overflow down draw method is a method in which molten glass overflows from both sides of a wedge-shaped refractory, and the overflowed molten glass is stretched downward and formed into a flat plate shape while joining at the lower end of the wedge shape. In the overflow down draw method, the surface to be the surface of the glass plate is not in contact with the refractory, and is formed in a free surface state. For this reason, the glass plate which is unpolished and has a good surface quality can be manufactured at low cost. Furthermore, it is easy to increase the area and thickness.

In addition to the overflow downdraw method, a glass plate can be formed by, for example, a slot down method, a redraw method, a float method, or a rollout method.

In the glass of the present invention, the thickness (in the case of a glass plate) is not particularly limited, but is preferably 1.0 mm or less, 0.7 mm or less, 0.5 mm or less, particularly 0.05 to 0.4 mm. is there. The smaller the wall thickness, the easier it is to reduce the weight of the organic EL display. The wall thickness can be adjusted by the flow rate during glass production, the forming speed (plate drawing speed), and the like.

As a method for industrially producing the glass of the present invention, the glass composition is SiO ₂ 67-73%, Al ₂ O ₃ 10-15%, B ₂ O ₃ 0-3%, Li ₂ Glass formulated to contain O + Na ₂ O + K ₂ O 0-0.5%, MgO 0-8.5%, CaO 3.5-12%, SrO 0-2.5%, BaO 1-6% The batch is put into a melting furnace and heated by energization with a heating electrode to obtain a molten glass, and the obtained molten glass is shaped into a flat plate having a thickness of 0.1 to 0.7 mm by an overflow down draw method. It is preferable to have the shaping | molding process shape | molded to glass.

The manufacturing process of a glass plate generally includes a melting process, a clarification process, a supply process, a stirring process, and a forming process. The melting step is a step of obtaining a molten glass by melting a glass batch prepared by mixing glass raw materials. The clarification step is a step of clarifying the molten glass obtained in the melting step by the action of a clarifier or the like. A supply process is a process of transferring a molten glass between each process. The stirring step is a step of stirring and homogenizing the molten glass. The forming step is a step of forming molten glass into a sheet glass. If necessary, a step other than the above, for example, a state adjusting step for adjusting the molten glass to a state suitable for molding may be introduced after the stirring step.

When industrially producing conventional low alkali glass, it is generally melted by heating with a burner flame. The burner is usually disposed above the melting kiln, and fossil fuel, specifically liquid fuel such as heavy oil, gaseous fuel such as LPG, or the like is used as the fuel. The combustion flame can be obtained by mixing fossil fuel and oxygen gas. However, in this method, since a large amount of moisture is mixed in the molten glass at the time of melting, the β-OH value tends to increase. Therefore, in producing the glass of the present invention, it is preferable to conduct current heating with a heating electrode, and melting with current heating with a heating electrode without heating with a burner combustion flame, that is, complete electric melting. Is preferred. This makes it difficult for moisture to be mixed into the molten glass during melting, so that the β-OH value is 0.30 / mm or less, 0.25 / mm or less, 0.20 / mm or less, 0.15 / mm or less, In particular, it becomes easy to regulate to 0.10 / mm or less. Furthermore, when conducting heating with a heating electrode, the amount of energy per mass for obtaining molten glass is reduced and the amount of molten volatiles is reduced, so that the environmental load can be reduced.

Furthermore, regarding this energization heating, the smaller the moisture content in the glass batch, the easier it is to reduce the moisture content in the glass plate. Then, the introduction material of B ₂ O ₃ is liable to be contaminated source of greatest moisture. Therefore, from the viewpoint of producing a low moisture glass plate, it is preferable to reduce the content of B ₂ O ₃ as much as possible. Further, the smaller the moisture content in the glass batch, the easier it is for the glass batch to spread uniformly in the melting kiln, so that it becomes easier to produce a homogeneous and high-quality glass plate.

It is preferable that the electric heating by the heating electrode is performed by applying an AC voltage to the heating electrode provided at the bottom or side of the melting kiln so as to contact the molten glass in the melting kiln. The material used for the heating electrode is preferably one having heat resistance and corrosion resistance against molten glass, for example, tin oxide, molybdenum, platinum, rhodium, etc. can be used. In particular, from the viewpoint of freedom of installation in the furnace, molybdenum Is preferred.

Since the glass of the present invention contains a small amount of alkali metal oxide, the electrical resistivity is high. Therefore, when applying current heating by the heating electrode to the low alkali glass, current flows not only in the molten glass but also in the refractory constituting the melting kiln, and the refractory constituting the melting kiln may be damaged early. is there. In order to prevent this, it is preferable to use a zirconia refractory having a high electrical resistivity, particularly a zirconia electroformed brick, as a refractory in the furnace, and a component that lowers the electrical resistivity in molten glass (glass composition) ( It is preferable to introduce a small amount of Li ₂ O, Na ₂ O, K ₂ O, Fe ₂ O _{3 and the} like, and particularly a small amount of Li ₂ O, Na ₂ O, K ₂ O and the like are introduced (for example, 0.01% by mass). As described above, it is particularly preferable to be 0.02% by mass or more. The content of Fe ₂ O ₃ is preferably 0.005 to 0.03% by mass, 0.008 to 0.025% by mass, and particularly preferably 0.01 to 0.02% by mass. Further, the content of ZrO ₂ in the zirconia refractory is preferably 85% by mass or more, particularly 90% by mass or more.

Hereinafter, the present invention will be described based on examples. However, the following examples are illustrative. The present invention is not limited to the following examples.

Tables 1 to 6 show examples of the present invention (sample Nos. 1 to 91). In the table, “NA” means not measured.

First, a glass batch in which glass raw materials were prepared so as to have the glass composition shown in the table was placed in a platinum crucible and melted at 1600 to 1650 ° C. for 24 hours. In melting the glass batch, the mixture was stirred and homogenized using a platinum stirrer. Next, the molten glass was poured onto a carbon plate, formed into a plate shape, and then annealed at a temperature near the annealing point for 1 hour. For each of the obtained samples, the density ρ, the average thermal expansion coefficient α in the temperature range of 30 to 380 ° C., the β-OH value, the strain point Ps, the annealing point Ta, the softening point Ts, and the high temperature viscosity of 10 ^4.5 dPa · s. , Temperature at high temperature viscosity 10 ^4.0 dPa · s, temperature at high temperature viscosity 10 ^3.0 dPa · s, temperature at high temperature viscosity 10 ^2.5 dPa · s, liquid phase viscosity logηatTL, Young's modulus E, rigidity G, Poisson's ratio γ, specific Young's modulus E / ρ, and HF etching rate (HF etching rate) were evaluated.

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

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

The β-OH value is a value measured by the above method.

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

The temperatures at high temperature viscosities of 10 ^4.5 dPa · s, 10 ^4.0 dPa · s, 10 ^3.0 dPa · s, and 10 ^2.5 dPa · s are values measured by the platinum ball pulling method.

The liquid phase viscosity log η at TL is a value obtained by measuring the viscosity of the glass at the liquid phase temperature TL by a platinum ball pulling method. The liquid phase temperature TL passes through a standard sieve 30 mesh (a sieve opening of 500 μm), puts the glass powder remaining in 50 mesh (a sieve opening of 300 μm) in a platinum boat, and holds it in a temperature gradient furnace for 24 hours. This is a value obtained by measuring the temperature at which crystals (initial phase) precipitate.

The Young's modulus E and the rigidity modulus G are values measured using a well-known resonance method. The Poisson's ratio is a value calculated from Young's modulus E and rigidity modulus G. Specific Young's modulus E / ρ is a value obtained by dividing Young's modulus by density.

The etching rate of HF is an etching depth when a mirror-polished glass surface is etched with a 10 mass% HF aqueous solution at 20 ° C. for 30 minutes.

As is apparent from Tables 1 to 9, the sample No. Nos. 1 to 91 have a low alkali metal oxide content, a strain point Ps of 734 ° C. or higher, a temperature at a high temperature viscosity of 10 ^2.5 dPa · s of 1693 ° C. or lower, and a liquid phase viscosity of 10 ^4.32 dPa · s. That was all. Therefore, sample no. Nos. 1 to 91 are considered to be suitable for carrier glass used when an organic EL element is produced on a substrate of an organic EL display or a polyimide substrate.

Claims

As a glass composition, SiO 2 67 to 73%, Al 2 O 3 10 to 15%, B 2 O 3 0 to less than 3%, Li 2 O + Na 2 O + K 2 O 0 to 0.5%, MgO 0 in mol%. -8.5%, CaO 3.5-12%, SrO 0-2.5%, BaO 1-6%, and the strain point (° C) divided by the Al 2 O 3 content (mol%). Glass having a measured value of 51 or more.
As a glass composition, SiO 2 67-73%, Al 2 O 3 10-15%, B 2 O 3 0-1.3%, Li 2 O + Na 2 O + K 2 O 0-0.5%, MgO 0 to 3.2%, CaO 3.5 to 12%, SrO 0 to 2%, BaO 3.5 to 6%, CaO- (SrO + BaO) is 3.1% or more, molar ratio CaO / Al 2 A glass characterized by having an O 3 of 1.05 or less and a molar ratio SrO / BaO of 0.03 to 0.50.
As glass composition, SiO 2 67-73%, Al 2 O 3 12-15%, B 2 O 3 0-1.8%, Li 2 O + Na 2 O + K 2 O 0-0.5% in mol% MgO 0-6%, CaO 5% or more, SrO 0-2%, BaO 3.5% or more, CaO- (SrO + BaO) 0.7% or more, and molar ratio SrO / BaO is 0.38 or less The molar ratio (MgO + CaO + SrO + BaO) / Al 2 O 3 is 1.09 to 1.70, and the value obtained by dividing the strain point (° C.) by the content (mol%) of Al 2 O 3 is 55 or more. Glass to do.