E-glass

Abstract

The present invention relates to an alkali-free glass, the strain point of the alkali-free glass is above 650 °C, and the average thermal expansion coefficient in the range of 50 °C to 350 °C is 30×10 ‑7 / °C to 45×10 ‑7 / °C, the temperature T 2 when the glass viscosity reaches 10 2 dPa·s is 1500 °C to 1800 °C. Expressed in mole % based on oxides, the alkali-free glass contains: SiO 2 : 62% to 70%, Al 2 O 3 : 9% to 16%, B 2 O 3 : 0 to 12%, MgO: 3% to 10%, CaO: 4% to 12%, SrO: 0 to 6%, Fe 2 O 3 : 0.001% to 0.04%, and MgO + CaO + SrO + BaO is 12% to 25%, and the β-OH value of the alkali-free glass is 0.35 / mm to 0.85 / mm.

Description

[0001] This application is a divisional application of a Chinese patent application with an application date of April 23, 2019 and an application number of 201980027779.7. Technical Field

[0002] The present invention relates to an alkali-free glass. More specifically, it relates to an ultraviolet-transmissive alkali-free glass suitable as a glass substrate used in various electronic device products or in the manufacturing process, or for supporting a glass substrate. Background Art

[0003] In recent years, the demand for glass substrates with high ultraviolet transmittance has been increasing. Examples of such substrates include: glass substrates in liquid crystal flat panel displays and the like having a structure obtained by bonding two glass substrates using an ultraviolet curable resin, and manufacturing support glass substrates for organic light emitting diodes (OLEDs) (e.g., flexible OLEDs including a polyimide layer) laminated on a support glass substrate. In the latter example, after the manufacturing process of the OLED, the adhesive layer on the support glass substrate is made non-adhesive by ultraviolet irradiation, and thus the support glass substrate is peeled off from the OLED. For devices characterized by light weight, thinness, or flexibility, such support glass substrates are useful for ensuring the necessary strength during the manufacturing process.

[0004] When these glass substrates contain alkali metal oxides, the alkali metal ions diffuse into the thin films formed on the substrates, deteriorating the film characteristics. Therefore, these glass substrates are required to be alkali-free glasses that substantially do not contain alkali metal ions.

[0005] Patent Documents 1 to 3 describe alkali-free glass substrates having an ultraviolet transmittance of 40% to 85% or 50% to 85% at a wavelength of 300 nm converted to a thickness of 0.5 mm.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2014 / 175215

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2006-36625

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2006-36626 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] Generally, mass-produced glass contains iron from raw materials and the manufacturing process. Iron exists in the glass as Fe 2+ or Fe3+ exists in the form of, especially Fe 3+ has absorption in the range below 300 nm in wavelength. Therefore, in order to improve the ultraviolet transmittance of an alkali-free glass (hereinafter, also simply referred to as "glass"), it is possible to consider reducing the iron content in the glass. However, when reducing the iron content of the glass, the infrared absorption amount of Fe 2+ decreases, resulting in an increase in the thermal conductivity of the glass. Thus, when manufacturing glass by heating a glass blank with the thermal rays of a burner flame in a kiln, the temperature distribution of the molten glass blank in the kiln becomes smaller, so the convection velocity decreases, and the bubble quality and homogeneity of the final product are likely to deteriorate. This is because the clarification (removal of bubbles) and the achievement of homogeneity depend on the existence of sufficient convection.

[0013] The subject of the present invention is to provide an alkali-free glass that has a high ultraviolet transmittance and can appropriately adjust the thermal conductivity.

[0014] Means for solving the problem

[0015] The present inventor found that by increasing the β-OH of the glass, infrared absorption is increased, that is, the thermal conductivity is reduced, while maintaining a low iron content and a high ultraviolet transmittance. However, when the thermal conductivity is excessively reduced, the molten glass blank at the bottom of the kiln is supercooled and it is difficult to flow. Therefore, it is important to control the thermal conductivity within an optimal range by adjusting the iron content and β-OH.

[0016] The following embodiments are included in the present invention. [1]

[0018] An alkali-free glass, wherein the strain point of the alkali-free glass is 650 °C or higher, the average thermal expansion coefficient in the range of 50 °C to 350 °C is 30×10 -7 / °C to 45×10 -7 / °C, the temperature T 2 when the glass viscosity reaches 10 2 is 1500 °C to 1800 °C,

[0019] Expressed in mol% on an oxide basis, the alkali-free glass contains:

[0020] SiO 2 : 62% to 70%,

[0021] Al 2 O 3 : 9% to 16%,

[0022] B 2 O 3 : 0 to 12%,

[0023] MgO: 3% to 10%,

[0024] CaO: 4% to 12%,

[0025] SrO: 0 to 6%,

[0026] Fe 2 O 3 : 0.001% to 0.04%, and

[0027] MgO + CaO + SrO + BaO is 12% to 25%, and

[0028] The β-OH value of the alkali-free glass is 0.35 / mm to 0.85 / mm. [2]

[0030] For the alkali-free glass described in [1], wherein the value of the alkali-free glass represented by the following formula A is 7 to 30,

[0031] Formula A:

[0032] (3.119×10 -4 T 2 2 -0.2014T 2 -17.38)[Fe 2 O 3 +(6.434×10 -7 T 2 2 +0.0144T 2 -7.842)[β-OH]

[0033] In formula A, [Fe 2 O 3 is the value of the total iron in terms of mol% of Fe 2 O 3 , and [β-OH] is the value expressed in units of / mm. [3]

[0035] For the alkali-free glass described in [1] or [2], wherein the effective thermal conductivity of the alkali-free glass at the temperature T 2 when the glass viscosity reaches 10 2 dPa·s is 40 W / (m·K) to 65 W / (m·K). [4]

[0037] For the alkali-free glass described in any one of [1] to [3], wherein the transmittance of the alkali-free glass converted to a plate thickness of 0.5 mm at a wavelength of 300 nm is 50% or more. [5]

[0039] The alkali-free glass according to any one of [1] to [4], wherein the alkali-free glass is in the shape of a glass plate and has a thickness of 0.05 mm to 3 mm. [6]

[0041] A method for manufacturing an alkali-free glass, which is a method for manufacturing the alkali-free glass according to any one of [1] to [5], wherein the method for manufacturing the alkali-free glass includes a step of forming molten glass by the float method or the fusion method. [7]

[0043] A display panel, wherein the display panel has the alkali-free glass according to any one of [1] to [5]. [8]

[0045] A semiconductor device, wherein the semiconductor device has the alkali-free glass according to any one of [1] to [5]. [9]

[0047] An information recording medium, wherein the information recording medium has the alkali-free glass according to any one of [1] to [5].

[0048] Advantages of the Invention

[0049] The alkali-free glass of the present invention has a high ultraviolet transmittance and a thermal conductivity adjusted to a desired value. Therefore, it is possible to provide a high-quality alkali-free glass that can be efficiently manufactured by heating means such as a burner flame and is suitable as a glass substrate or a support glass substrate for various electronic devices such as thin-film displays and organic electroluminescence. Detailed Embodiments

[0050] In the present embodiment, the "alkali-free" glass means a glass that substantially does not contain alkali metal oxides such as Na 2 O and K 2 O. "Substantially does not contain" means that this component is not added except for substances inevitably contained as impurities. In the present invention, substantially not containing alkali metal oxides means, for example, that the content of alkali metal oxides is 0.5% or less, preferably 0.2% or less, more preferably 0.1% or less, more preferably 0.08% or less, further preferably 0.05% or less, and most preferably 0.03% or less (mol% based on oxides).

[0051] The alkali-free glass according to the present embodiment, in addition to SiO that forms the glass skeleton 2 、Al 2 O 3In addition, it further contains a specified amount of a metal oxide component. Hereinafter, the content of each component in the alkali-free glass according to the present embodiment will be described on the basis of oxides. Hereinafter, unless otherwise specified, "%" means "mol%".

[0052] SiO 2 has a content of 62% to 70%. SiO 2 is preferably 63% or more, more preferably 64% or more, still more preferably 65% or more, and particularly preferably 65.5% or more. When the content of SiO 2 is less than the lower limit value, there is a tendency that the strain point is low, the thermal expansion coefficient and the specific gravity become high, and the hydrofluoric acid resistance deteriorates. It should be noted that hydrofluoric acid and buffered hydrofluoric acid (BHF: a mixture of hydrofluoric acid and ammonium fluoride) are chemicals commonly used in etching processes related to semiconductor formation and thinning. On the other hand, the content of SiO 2 is preferably 69% or less, more preferably 68.5% or less, still more preferably 68% or less, and particularly preferably 67.5% or less. When the content of SiO 2 exceeds the upper limit value, there is a tendency that the temperature (T 2 ) at which the glass viscosity reaches 10 2 Poise (dPa·s) becomes high, the melting property deteriorates, and the devitrification temperature rises.

[0053] Al 2 O 3 has a content of 9% to 16%. Al 2 O 3 is preferably 10% or more, more preferably 10.5% or more, still more preferably 10.8% or more, and particularly preferably 11% or more. When the content of Al 2 O 3 is less than the lower limit value, there is a tendency that phase separation control becomes difficult, the strain point decreases, and the thermal expansion coefficient becomes high. On the other hand, the content of Al 2 O 3 is preferably 15% or less, more preferably 14% or less, still more preferably 13.8% or less, and particularly preferably 13.5% or less. When the content of Al 2 O 3 exceeds the upper limit value, there is a tendency that T 2 rises, resulting in deteriorated melting property and also a high devitrification temperature.

[0054] B 2 O 3 has a content of 0 to 12%. B 2 O 3 is not an essential component, but B 2 O 3To make the melting reactivity of the glass during manufacturing good, lower the devitrification temperature, and improve the BHF resistance, it can contain B 2 O 3 。B 2 O 3 The content of B 2 O 3 is preferably 0.5% or more, more preferably 0.8% or more, further preferably 1% or more, and particularly preferably 1.2% or more. On the other hand, the content of B 2 O 3 is preferably 11% or less, more preferably 10% or less, further preferably 9% or less, and particularly preferably 8.5% or less. When the content of B 2 O 3 exceeds the upper limit value, there is a tendency for the strain point to decrease.

[0055] The content of MgO is 3% - 10%. The content of MgO is preferably 4% or more, more preferably 4.5% or more, further preferably 5% or more, and particularly preferably 5.5% or more. Compared with other alkaline earths, MgO has the effects of improving the melting property, reducing the specific gravity, and improving the hydrofluoric acid resistance without increasing the thermal expansion coefficient. However, when its content is less than the lower limit value, it is difficult to fully obtain these effects. On the other hand, the content of MgO is preferably 9.7% or less, more preferably 9.5% or less, further preferably 9.3% or less, and particularly preferably 9.1% or less. When the content of MgO exceeds the upper limit value, the devitrification temperature may become high.

[0056] The content of CaO is 4% - 12%. The content of CaO is preferably 4.2% or more, more preferably 4.5% or more, further preferably 4.7% or more, and particularly preferably 5% or more. Among the alkaline earths, CaO, second only to MgO, also has the characteristics of not increasing the thermal expansion coefficient and not greatly reducing the strain point, and also improves the melting property like MgO. When its content is less than the lower limit value, it is difficult to fully obtain these effects. On the other hand, the content of CaO is preferably 11.5% or less, more preferably 11% or less, further preferably 10.5% or less, and particularly preferably 10% or less. When the content of CaO exceeds the upper limit value, there is a tendency for the thermal expansion coefficient to become high. In addition, when the content of CaO exceeds the upper limit value, the devitrification temperature may become high.

[0057] The content of SrO is 0 to 6%. In order to improve the meltability during glass manufacturing without increasing the devitrification temperature of the glass, SrO can be contained. The content of SrO is preferably 0.1% or more, more preferably 0.5% or more, further preferably 1% or more, and particularly preferably 1.2% or more. On the other hand, the content of SrO is preferably 5.8% or less, more preferably 5.5% or less, further preferably 5.3% or less, and particularly preferably 5.0% or less. When the content of SrO is greater than the upper limit value, there is a tendency for the specific gravity and thermal expansion coefficient to increase and the hydrofluoric acid resistance to deteriorate.

[0058] BaO is not an essential component, but in order to improve the meltability without increasing the devitrification temperature of the glass, BaO can be contained. However, when a large amount of BaO is contained, there is a tendency for the specific gravity to increase and the average thermal expansion coefficient to become too large. Therefore, the content of BaO is preferably 1% or less, more preferably 0.5% or less, further preferably 0.1% or less. It is particularly preferred that BaO is substantially not contained.

[0059] The total amount of alkaline earth metal oxides in the alkali-free glass according to the present embodiment, that is, MgO + CaO + SrO + BaO (hereinafter also referred to as "RO"), is 12% to 25%. RO is preferably 13% or more, more preferably 14% or more, further preferably 15% or more, and particularly preferably 15.5% or more. When RO is less than the lower limit value, the meltability of the glass deteriorates. In addition, when RO is less than the lower limit value, the devitrification temperature may increase. On the other hand, RO is preferably 23% or less, more preferably 21% or less, further preferably 20.5% or less, and particularly preferably 20% or less. When RO is greater than the upper limit value, there is a tendency for the strain point to decrease, the specific gravity to increase, the thermal expansion coefficient to increase, and the hydrofluoric acid resistance to decrease.

[0060] The content of iron in the alkali-free glass according to the present embodiment is Fe 2 O 3 converted to 0.001% to 0.04%. Fe 2 O 3 is preferably 0.002% or more, more preferably 0.003% or more, further preferably 0.0035% or more, and particularly preferably 0.004% or more. In addition, Fe 2 O 3 is preferably 0.03% or less, more preferably 0.02% or less, further preferably 0.018% or less, and particularly preferably 0.016% or less.

[0061] As described above, the content of Fe 2 O 3 contributes to the reduction of the ultraviolet transmittance. Therefore, it is considered that in the glass where ultraviolet transmittance is required, Fe 2 O3 The content of [substance] is set to a low content. However, when reducing the Fe content in the glass 2 O 3 content, the infrared absorption ability also decreases as a result, leading to an increase in thermal conductivity. In this embodiment, a detailed study was conducted on the balance with β-OH described later, and as a result, the above Fe 2 O 3 content range was found.

[0062] For the glass according to this embodiment, in addition to the above components, in order to improve its meltability, fining property, formability, etc., ZrO 2 , ZnO, SO 3 , F, Cl, and SnO 2 may be contained singly or in combination in a total amount of 2% or less, preferably 1% or less, more preferably 0.5% or less.

[0063] On the other hand, in order not to deteriorate the characteristics of a thin film such as a metal or an oxide provided on the surface of the glass plate, the glass according to this embodiment preferably substantially does not contain P 2 O 5 . In addition, in order to make the glass easily recyclable, it preferably substantially does not contain PbO, As 2 O 3 , Sb 2 O 3 .

[0064] The β-OH value, which is an index of the water content, of the alkali-free glass according to this embodiment is 0.35 / mm to 0.85 / mm. The β-OH value is preferably 0.40 / mm or more, more preferably 0.45 / mm or more, further preferably 0.48 / mm or more, and particularly preferably 0.50 / mm or more. In addition, the β-OH value is preferably 0.8 / mm or less, more preferably 0.77 / mm or less, further preferably 0.75 / mm or less, and particularly preferably 0.7 / mm or less.

[0065] When the β-OH value is increased, the thermal conductivity can be reduced without reducing the ultraviolet transmittance. However, when the thermal conductivity is excessively reduced, the above-mentioned drawbacks may also occur. The inventors analyzed the contribution degrees of both in the reduction of the thermal conductivity near the melting temperature by using combinations of different iron amounts and β-OH values, and found the above β-OH value range that is particularly suitable for the manufacture of high-ultraviolet-transmittance alkali-free glass.

[0066] The β-OH value in the alkali-free glass can be adjusted by methods known to those skilled in the art. For example, the β-OH value can be adjusted higher by using a hydroxide as a glass raw material (especially a supply source of Mg or Ca) or by increasing the water vapor partial pressure or dew point of the melting atmosphere.

[0067] The strain point of the non-alkali glass according to the present embodiment is 650 °C or higher. When the strain point is lower than 650 °C, thermal shrinkage occurs during the heat treatment required in the manufacture of electronic devices, which may lead to a reduction in the yield. The strain point is preferably 655 °C or higher, more preferably 660 °C or higher, further preferably 663 °C or higher, and particularly preferably 665 °C or higher. When the strain point is too high, the temperature of the forming device needs to be increased accordingly, and the life of the forming device tends to be reduced. Therefore, the strain point is preferably 770 °C or lower, more preferably 750 °C or lower, further preferably 740 °C or lower, and particularly preferably 730 °C or lower.

[0068] The average thermal expansion coefficient of the non-alkali glass according to the present embodiment in the range of 50 °C to 350 °C is 30×10 -7 / °C to 45×10 -7 / °C. The average thermal expansion coefficient in the range of 50 °C to 350 °C is preferably 33×10 -7 / °C or more, more preferably 35×10 -7 / °C or more, further preferably 36×10 -7 / °C or more, and particularly preferably 37×10 -7 / °C or more. For example, in the manufacture of the TFT side substrate of a flat panel display, sometimes a gate metal film such as copper and a gate insulating film such as silicon nitride are sequentially laminated on the non-alkali glass. However, when the average thermal expansion coefficient is less than the lower limit value, the difference in the expansion rate between the gate insulating film and the glass becomes too small. Therefore, the effect of eliminating the warping of the glass caused by the formation of the gate metal film by the gate insulating film is reduced. As a result, problems such as an increase in the warping of the substrate, poor conveyance, or a large pattern deviation during exposure may occur. On the other hand, the average thermal expansion coefficient in the range of 50 °C to 350 °C is preferably 43×10 -7 / °C or less, more preferably 42×10 -7 / °C or less, further preferably 40×10 -7 / °C or less, and particularly preferably 39×10 -7 / °C or less. The glass with an average thermal expansion coefficient below the upper limit value has strong thermal shock and can achieve a high yield.

[0069] The temperature T 2 at which the viscosity of the non-alkali glass according to the present embodiment reaches 10 2 Poise (dPa·s) is 1500 °C to 1800 °C. T 2 is preferably 1550 °C or higher, more preferably 1570 °C or higher, more preferably 1580 °C or higher, and particularly preferably 1600 °C or higher. When T 2When it is less than the lower limit value, it is possible that the melting temperature of the glass deviates from the fining temperature, resulting in poor fining property of the glass. In addition, when T 2 is less than the lower limit value, erosion of the melting furnace caused by the low-viscosity molten liquid is likely to occur, and the life of the manufacturing apparatus may be shortened. On the other hand, T 2 is preferably 1750 °C or lower, more preferably 1730 °C or lower, further preferably 1700 °C or lower, and particularly preferably 1660 °C or lower. When T 2 is greater than the upper limit value, the meltability of the glass is poor and a high temperature is required, thus increasing the burden on the manufacturing apparatus.

[0070] The viscosity of the alkali-free glass according to the present embodiment reaches 10 4 Poise (dPa·s) at temperature T 4 is preferably 1400 °C or lower, more preferably 1370 °C or lower, further preferably 1350 °C or lower, and particularly preferably 1320 °C or lower. Glass having these T 4 is suitable for forming by the float process. When T 4 is high, it is possible to greatly shorten the life of the shell structure of the float kiln and the heater.

[0071] The alkali-free glass according to the present embodiment preferably has an effective thermal conductivity of 40 W / (m·K) to 65 W / (m·K) for the glass when the viscosity reaches 10 2 dPa·s at temperature T 2 . The effective thermal conductivity at T 2 is more preferably 45 W / (m·K) or more, further preferably 50 W / (m·K) or more, and particularly preferably 55 W / (m·K) or more. In addition, the effective thermal conductivity of the glass at T 2 is more preferably 63 W / (m·K) or less, further preferably 60 W / (m·K) or less, and particularly preferably 57 W / (m·K) or less.

[0072] The effective thermal conductivity refers to the thermal conductivity measured by the steady-state method (J. Am. Cer. Soc. 44, 1961, pp. 333-339), and is sometimes also referred to as "apparent thermal conductivity". By having the above effective thermal conductivity at temperature T 2 , the best convection velocity is generated during glass melting by heating, the heating becomes efficient, and thus a glass product with excellent bubble quality and homogeneity can be provided.

[0073] The value represented by formula A of the alkali-free glass according to the present embodiment is preferably 7 to 30.

[0074] Formula A:

[0075] (3.119×10 -4 T2 2 -0.2014T 2 -17.38)[Fe 2 O 3 +(6.434×10 -7 T 2 2 +0.0144T 2 -7.842)[β-OH]

[0076] Herein, [Fe 2 O 3 is the value of the mole % of the total iron converted to Fe 2 O 3 , and [β-OH] is the value expressed in units of / mm.

[0077] The above formula A is derived by analyzing in detail how much each of the amount of Fe 2 O 3 and the value of β-OH contributes to the reduction of the thermal conductivity at different temperatures.

[0078] The value represented by formula A is an index indicating how much the thermal conductivity is reduced compared to the case of an alkali-free glass containing neither moisture nor iron. The larger the value of formula A, the greater the reduction in the thermal conductivity. The value of formula A is more preferably 10 or more, further preferably 12 or more, and particularly preferably 14 or more. In addition, the value of formula A is more preferably 25 or less, further preferably 20 or less, and particularly preferably 17 or less.

[0079] Preferably, the transmittance of the alkali-free glass according to this embodiment converted to a plate thickness of 0.5 mm at a wavelength of 300 nm is 50% or more. Thereby, the ultraviolet transmittance suitable for use as a substrate or a support substrate for various electronic devices is ensured. The above transmittance is more preferably 60% or more, further preferably 70% or more, and particularly preferably 80% or more.

[0080] The alkali-free glass according to this embodiment is preferably in the shape of a glass plate. The thickness of the glass plate is preferably 3 mm or less, more preferably 2 mm or less, more preferably 1.5 mm or less, further preferably 1.2 mm or less, and particularly preferably 0.8 mm or less. In addition, the thickness of the glass plate is preferably 0.05 mm or more, more preferably 0.1 mm or more, more preferably 0.15 mm or more, further preferably 0.2 mm or more, and particularly preferably 0.3 mm or more.

[0081] The alkali-free glass according to the present embodiment can be manufactured by appropriately combining methods known to those skilled in the art. For example, raw materials of the above components are formulated so as to have the above-specified composition, continuously fed into a melting furnace, and heated to 1500°C to 1800°C for melting to obtain molten glass. The obtained molten glass is formed into a glass ribbon with a specified plate thickness by a forming device, and the glass ribbon is slowly cooled and then cut.

[0082] The manufacturing method of the glass and glass plate of the present embodiment is not particularly limited, and various methods can be applied. For example, raw materials of each component are formulated so as to have a target composition, and they are heated and melted in a glass melting furnace. The glass is homogenized by bubbling, stirring, adding fining agents, etc., and formed into a glass plate with a specified thickness by methods such as the float process, pressing process, fusion process, or down-draw process. After slow cooling, processing such as grinding and polishing can be performed as needed to obtain a glass substrate with a specified size and shape. By using the fusion process, the average cooling rate near the glass transition temperature becomes faster, and when the obtained glass plate is further thinned by hydrofluoric acid etching treatment, the surface roughness of the glass plate on the surface of the side where the etching treatment is performed becomes smaller.

[0083] From the viewpoint of stably producing large-sized sheet glass (for example, one side is 1800 mm or more), the float process is preferably used.

[0084] A large-sized substrate refers to a glass plate with at least one side being 1800 mm or more. As a specific example, a glass plate with a long side of 1800 mm or more and a short side of 1500 mm or more is preferred. The alkali-free glass of the present embodiment more preferably uses a glass plate with at least one side being 2400 mm or more, for example, a glass plate with a long side of 2400 mm or more and a short side of 2100 mm or more, further preferably uses a glass plate with at least one side being 3000 mm or more, for example, a glass plate with a long side of 3000 mm or more and a short side of 2800 mm or more, particularly preferably uses a glass plate with at least one side being 3200 mm or more, for example, a glass plate with a long side of 3200 mm or more and a short side of 2900 mm or more, and most preferably uses a glass plate with at least one side being 3300 mm or more, for example, a glass plate with a long side of 3300 mm or more and a short side of 2950 mm or more.

[0085] Next, a display panel according to an embodiment of the present invention will be described.

[0086] The display panel of the present embodiment has the alkali-free glass of the above embodiment as a glass substrate. As long as it has the alkali-free glass of the above embodiment, the display panel is not particularly limited and can be various display panels such as a liquid crystal display panel and an organic electroluminescence display panel.

[0087] Taking the case of a thin-film transistor liquid crystal display (TFT-LCD) as an example, the thin-film transistor liquid crystal display has: a display surface electrode substrate (array substrate) on which a gate electrode line and an oxide layer for gate insulation are formed on its surface, and a pixel electrode is formed on the surface of the oxide layer, and a color filter substrate on which an RGB color filter and a counter electrode are formed on its surface, and a liquid crystal material is sandwiched between the array substrate and the color filter substrate that are paired with each other to form a cell. In addition to such cells, the liquid crystal display panel also includes other components such as a peripheral circuit. The liquid crystal display panel of the present embodiment uses the alkali-free glass of the above embodiment in at least one of a pair of substrates constituting the cell.

[0088] Next, a semiconductor device according to an embodiment of the present invention has the alkali-free glass of the above embodiment as a glass substrate. Specifically, for example, it has the alkali-free glass of the above embodiment as a glass substrate for an image sensor such as MEMS, CMOS, CIS, etc. In addition, it has the alkali-free glass of the above embodiment as a protective glass for a display device for projection use, for example, a protective glass for LCOS (liquid crystal on silicon).

[0089] Next, an information recording medium according to an embodiment of the present invention has the alkali-free glass of the above embodiment as a glass substrate. Specifically, for example, it has the alkali-free glass of the above embodiment as a glass substrate for a magnetic recording medium or an optical disc. As the magnetic recording medium, for example, there are an energy-assisted magnetic recording medium and a perpendicular magnetic recording medium.

[0090] Examples

[0091] Hereinafter, the embodiments of the present invention will be described in more detail by way of examples and comparative examples, but the present invention is not limited to these examples.

[0092] The raw materials of each component were formulated so that the glass composition became the target composition shown in Tables 1 and 2 (unit: mol%), and melted for 6 hours at a temperature of 1650 °C using a platinum crucible while stirring with a stirrer. After melting, it was poured onto a carbon plate, held at the glass transition temperature +30 °C for 60 minutes, and then cooled to room temperature at a rate of 1 °C per minute. The obtained alkali-free glass was mirror-polished to form a glass plate, and various evaluations were carried out. Examples 1 to 4, 7 to 10 are examples of the present invention, and Examples 5, 6, 11, 12 are comparative examples.

[0093] The X-ray intensity of each component on the surface of the glass obtained above was measured using an X-ray fluorescence device (XRF) (manufactured by Rigaku Corporation, ZSX100e) and quantitatively analyzed to confirm the composition.

[0094] The average coefficient of thermal expansion in the range of 50°C to 350°C (unit: ×10 -7 / °C) was measured according to the method specified in JIS R3102 (1995) using a differential thermal dilatometer (TMA). The strain point (unit: °C) was measured according to the method specified in JIS R3103-2 (2001) by the fiber elongation method. The T 2 and T 4 were measured using a rotational viscometer. For the thermal conductivity, the effective thermal conductivity of the glass (hereinafter, also referred to as Keff) was measured according to the steady-state method (J. Am. Cer. Soc. 44, 1961, pp. 333-339).

[0095] After melting the glass of each example at temperature T 2 using a crucible for measuring effective thermal conductivity to prepare a glass melt, the effective thermal conductivity (Keff) of the glass at temperature T 2 was evaluated.

[0096] The effective thermal conductivity (Keff) was obtained by separately measuring the following parameters and using Equation B: the thermal conductivity of the crucible containing the glass melt was set as Kr, the thickness of the bottom surface of the crucible was set as dr, the depth of the glass melt in the crucible was set as dg, the temperature of the glass melt surface was set as Ts, the temperature of the inner bottom surface of the crucible at the interface of the glass melt and the inner bottom surface of the crucible was set as Tb, and the temperature of the outer bottom surface of the crucible on the outer bottom surface of the crucible was set as Tr.

[0097] Equation B: Keff = Kr{(Tb - Tr) / (Ts - Tb)}(dg / dr)

[0098] The thermal conductivity Kr of the crucible was obtained by separately measuring the thickness dr of the bottom surface of the crucible, the depth dg of the glass melt, the temperature Ts of the glass melt surface, the interface temperature Tb of the glass melt and the inner bottom surface of the crucible, and the temperature Tr of the outer bottom surface of the crucible using glasses 1 and 2 with known effective thermal conductivities shown in Table 3 and using Equation B.

[0099] The ultraviolet transmittance was measured according to ISO-9050:2003 using a Hitachi spectrophotometer U-4100. The transmittance converted to a plate thickness of 0.5 mm at a wavelength of 300 nm was obtained.

[0100] The β-OH value was obtained as follows: the double-sided mirror polishing of the glass sample was performed so that the plate thickness became 0.70 mm to 2.0 mm, and then the transmittance was measured using FT-IR in the range of wavenumbers 4000 cm -1 to 2000 cm -1 . The transmittance at a wavenumber of 4000 cm -1 was set as τ 1[%], set the minimum value of the transmittance near the wave number 3600 cm -1 to τ 2 [%], set the plate thickness of the glass to X [mm], and calculated the β-OH value according to the following formula. It should be noted that the plate thickness of the glass sample was adjusted so that τ 2 fell within the range of 20% to 60%.

[0101] β-OH [mm -1 = (1 / X) log 10 (τ 1 / τ 2 )

[0102] Table 1

[0103]

[0104] Table 2

[0105]

[0106] Table 3

[0107] Glass 1 Glass 2 <![CDATA[SiO 2 > 71.3 69.3 <![CDATA[Al 2 O 3 > 1.0 1.1 CaO 9.1 9.0 MgO 5.7 6.9 <![CDATA[Sodium 2 O]]> 12.5 12.8 <![CDATA[K 2 O]]> 0.3 0.5 <![CDATA[TiO 2 > 0.022 0.015 <![CDATA[Fe 2 O 3 > 0.031 0.449 Co 0 0.0233 Se 0 0.0023 Cr 0 0.0040 Effective thermal conductivity (1600 °C) [W / (m·K)] 119.0 19.7 Effective thermal conductivity (1500 °C) [W / (m·K)] 87.4 17.4 Effective thermal conductivity (1400 °C) [W / (m·K)] 62.8 15.2 Effective thermal conductivity (1300 °C) [W / (m·K)] 45.2 12.9 Effective thermal conductivity (1200 °C) [W / (m·K)] 34.5 10.7 Effective thermal conductivity (1100 °C) [W / (m·K)] 30.7 8.4

[0108] As shown in Tables 1 and 2, the contents of the respective components of the glasses of Examples 1 to 4 and 7 to 10, particularly Fe 2 O 3 and the β-OH value are within the specified ranges, and while maintaining a high ultraviolet transmittance, a moderate low thermal conductivity is ensured. Therefore, these glasses can be made into alkali-free glasses with excellent bubble quality and homogeneity. The physical properties suitable for use as substrates or support substrates for various electronic devices are also ensured.

[0109] In contrast, the glasses of Examples 5 and 11 have a high content of Fe 2 O 3 , so the thermal conductivity is low. On the other hand, the necessary ultraviolet transmittance cannot be ensured. The glasses of Examples 6 and 12 achieved a high ultraviolet transmittance through low iron content, but the thermal conductivity became too high. The glasses of Examples 6 and 12 have a high thermal conductivity, and the bubble quality and homogeneity of the final products are poor. It can be understood that this shortcoming of the glasses of Examples 6 and 12 is compensated for by the β-OH value in the glasses of Examples 1 to 4 and 7 to 10.

[0110] The present invention has been described in detail and with reference to specific embodiments, but various changes or modifications can be made without departing from the spirit and scope of the present invention, which will be obvious to those skilled in the art.

[0111] This application is based on Japanese Patent Application 2018-086580 filed on April 27, 2018, the content of which is incorporated herein by reference.

[0112] Industrial applicability

[0113] The alkali-free glass according to the embodiment of the present invention can be used for various applications including all electronic devices, and is particularly suitable for applications that require high ultraviolet transmittance, such as thin display devices, glass substrates for organic electroluminescent devices, or supporting glass substrates.

Claims

1. An alkali-free glass, wherein, The strain point of the non-alkali glass is above 650 °C, and the average thermal expansion coefficient in the range of 50 °C to 350 °C is 30×10 -7 / °C to 45×10 -7 / °C. The temperature T 2 when the glass viscosity reaches 10 2 dPa·s is 1500 °C to 1800 °C. expressed in mol% based on oxides, the alkali-free glass comprises: SiO 2 : 62% to 70%, Al 2 O 3 : 9% - 16%, B 2 O 3 : 0.5 to 12%, MgO: 5.6% to 10%, CaO: 4% to 10%, SrO: 0.1 to 6%, Fe 2 O 3 : 0.001% to 0.04%, MgO + CaO + SrO + BaO is 15.6% to 20.5%, the value of the alkali-free glass represented by the following formula A is 7 to 30, Formula A: (3.119×10 -4 T 2 2 -0.2014T 2 -17.38)[Fe 2 O 3 +(6.434×10 -7 T 2 2 +0.0144T 2 -7.842)[β-OH] In formula A, [Fe 2 O 3 is the value of the mole percentage of total iron converted to Fe 2 O 3 , and [β-OH] is the value expressed in units of / mm.

2. The alkali-free glass according to claim 1, wherein, the β-OH value of the alkali-free glass is 0.35 / mm to 0.85 / mm.

3. The alkali-free glass according to claim 1 or 2, wherein, The temperature T at which the glass viscosity of the E-glass reaches 10 2 dPa·s has an effective thermal conductivity of 40 W / (m·K) to 65 W / (m·K). 2 ​ 4. The alkali-free glass according to claim 1 or 2, wherein, the transmittance of the alkali-free glass converted to a plate thickness of 0.5 mm at a wavelength of 300 nm is 50% or more.

5. The alkali-free glass according to claim 1 or 2, wherein, the alkali-free glass is in the shape of a glass plate and has a thickness of 0.05 mm to 3 mm.

6. A method for manufacturing an alkali-free glass, which is a method for manufacturing the alkali-free glass according to claim 1 or 2, wherein, the method for manufacturing the alkali-free glass comprises a step of forming molten glass by a float process or a fusion process.

7. A display panel, wherein, the display panel has the alkali-free glass according to claim 1 or 2.

8. A semiconductor device, wherein, the semiconductor device has the alkali-free glass according to claim 1 or 2.

9. An information recording medium, wherein, the information recording medium has the alkali-free glass according to claim 1 or 2.

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