Glass plate and method for producing same

Abstract

To provide a novel glass plate which can be used for a substrate or a window material of a high-frequency device and has small propagation loss and transmission loss in a high-frequency band.SOLUTION: The glass plate has a dielectric loss tangent of tan δ A at the 10GHz and a glass-transition temperature of Tg °C, and satisfies (tan δ 100-tan δ A) ≥ 0.0004, wherein tan δ 100 is a dielectric loss tangent when the glass plate is heated to (Tg + 50) °C and then cooled to (Tg - 150) °C at a rate of 100 °C / min.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a glass plate and a method for producing the same. [Background technology]

[0002] It has become commonplace to use devices that use radio waves, such as radar and mobile phones, in vehicles including automobiles and indoors in buildings. In particular, in recent years, there has been active development of devices that use radio waves in the high frequency band (microwave to millimeter wave), more specifically in the gigahertz frequency band, for example, in the 3 to 300 GHz range.

[0003] Circuit boards used in such radio wave-utilizing equipment for high frequency applications (hereinafter referred to as "high frequency devices") generally use insulating substrates such as resin substrates, ceramic substrates, glass substrates, etc. Insulating substrates used in high frequency devices are required to reduce transmission loss due to dielectric loss, conductor loss, etc. in order to ensure characteristics such as the quality and strength of high frequency signals.

[0004] On the other hand, glass sheets used as window materials for vehicles such as automobiles and buildings have been required to have high visible light transmittance, high ultraviolet and solar radiation shielding performance, and good visual appearance. Patent Document 1 discloses ultraviolet and infrared absorbing glass made of soda-lime-silica glass having a specific composition. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2002-348143 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in view of the fact that millimeter-wave radars will be installed inside vehicles such as automobiles and that electronic devices will be used inside buildings, the glass sheets used as window materials for these devices will also be required to have reduced propagation loss and transmission loss, just as insulating substrates for high-frequency devices are.

[0007] Therefore, an object of the present invention is to provide a novel glass plate that can be used as a substrate or window material for high-frequency devices and has small propagation loss and transmission loss in high-frequency bands, and a method for producing the same. [Means for solving the problem]

[0008] The present invention relates to the following: A glass plate having a dielectric loss tangent tanδA at 1.10 GHz and a glass transition temperature Tg°C, The glass plate satisfies (tanδ100-tanδA)≧0.0004 when the dielectric loss tangent at 10 GHz is tanδ100 after heating the glass plate to (Tg+50)°C and then cooling it to (Tg-150)°C at a rate of 100°C / min. The relative permittivity at 2.10 GHz is εrA, 2. The glass plate according to 1, wherein, when the temperature of the glass plate is increased to (Tg+50)°C and then decreased to (Tg-150)°C at a rate of 100°C / min, the relative dielectric constant at 10 GHz is defined as εr100, and the relationship between the dielectric constant and the dielectric constant at 10 GHz is 0.95≦(εr100 / εrA)≦1.05. 3. The area of ​​the main surface is 350 cm 2 3. The glass plate according to 1 or 2 above. 4. The glass plate according to any one of 1 to 3 above, which has a dielectric loss tangent of 0.009 or less at 4.10 GHz. 5. The glass plate according to any one of 1 to 4 above, which has a relative dielectric constant of 6.8 or less at 5.10 GHz. 6. The glass plate according to any one of 1 to 5 above, wherein the difference in dielectric loss tangent at 10 GHz between any two points spaced apart by 6.40 mm or more is 0.0005 or less. 7. The glass plate according to any one of 1 to 6 above, wherein the difference in relative permittivity at 10 GHz between any two points spaced apart by 7.40 mm or more is 0.05 or less. 8. The glass plate according to any one of 1 to 7 above, which contains 30 to 85% of SiO2 in terms of mole percentage based on oxides. 9. In mole percentage based on oxide, SiO2 57-70% Al2O3 5-15% B2O3 15-24% Al2O3+B2O320~40% Al2O / (Al2O3+B2O3) 0.1~0.45 MgO 0-10% CaO 0-10% SrO 0-10% BaO 0-10% Li2O 0~5% Na2O 0-5% K2O 0-5%, and R2O (R = alkali metal) 0-5% 9. The glass plate according to any one of 1 to 8 above, comprising: 10. In mole percentage based on oxide, SiO2 55-80% Al2O30-15% SiO2+Al2O355~90% B2O3 0-15% MgO 0-20% CaO 0-20% SrO 0-15% BaO 0-15% MgO+CaO 0~30% MgO+CaO+SrO+BaO 0~30% Li2O 0~20% Na2O 0-20% K2O 0-20%, and R2O (R = alkali metal) 0-20% 9. The glass plate according to any one of 1 to 8 above, comprising: 11. The glass plate according to any one of 1 to 9 above, which is used as a substrate for a high-frequency device that handles high-frequency signals of 3.0 GHz or higher. 12. The glass plate according to any one of 1 to 8 and 10 above, which is used as a window material. 13. A method for producing the glass plate according to any one of 1 to 12 above, comprising: A melting and forming process in which the molten glass obtained by melting glass raw materials is formed into a sheet. a temperature-reducing step of reducing the temperature of the molten glass formed into a plate shape to a temperature of (Tg-300)°C or lower relative to the glass transition temperature Tg (°C) to obtain a raw glass plate; a heat treatment step in which the obtained glass plate is heated from a temperature of not more than (Tg-300)°C to a range of (Tg-100)°C to (Tg+50)°C without exceeding (Tg+50)°C, and then cooled again to not more than (Tg-300)°C; The heat treatment step is carried out once or twice or more times, One heat treatment step is a period from when the temperature of the glass plate exceeds (Tg-300)°C, passes through a maximum temperature Temax°C in the range of (Tg-100)°C to (Tg+50)°C, and then drops to (Tg-300)°C or lower again. During the entire heat treatment process, the total time during which the temperature of the glass plate is in the range of (Tg-100)°C to (Tg+50)°C is equal to or longer than K (minutes) expressed by the following formula (1), where Tmax°C is the maximum temperature of the glass plate during the entire heat treatment process: a method for producing a glass plate, wherein, in each of the heat treatment steps, when a time from the last time at which the temperature starts to decrease from the maximum temperature Temax °C in the heat treatment step to the time at which the temperature finally passes (Tg-110) °C is defined as t1 (minutes), the following formula (2) is satisfied: K=[{(Tg+50)-Tmax} / 10]+15 Formula (1) {Temax-(Tg-110)} / t1≦10 Equation (2) 14. The method for producing a glass plate according to 13, wherein, in each heat treatment step, the temperature of the glass plate is lowered from the maximum temperature Temax°C and, after initially falling below (Tg-110)°C, does not again exceed (Tg-110)°C. 15. In each of the heat treatment steps, any two times between the last time when the temperature starts to decrease from the maximum temperature Temax ° C. for each of the heat treatment steps and the last time when the temperature passes through (Tg-110) ° C. are designated as t2 (minutes), t3 (minutes), and t2 <t3とするとき、 The difference between the time t2 and the time t3 is 1 minute or more, 15. The method for producing a glass plate according to 13 or 14 above, wherein the temperature of the glass plate at t2 is Te2 and the temperature of the glass plate at t3 is Te3, and the following formula (3) is satisfied: (Te2-Te3) / (t3-t2)≦10 Formula (3) 16. The method for producing a glass plate according to any one of 13 to 15 above, wherein the average temperature-lowering rate from (Tg+50)°C to (Tg-100)°C in the temperature-lowering step is more than 10°C / min. 17. The method for producing a glass plate according to any one of the above 13 to 16, wherein the average temperature lowering rate in the temperature lowering step is 10 to 1000° C. / min. [Effects of the Invention]

[0009] The glass sheet according to the present invention exhibits low absorption of electromagnetic waves in the high-frequency band and achieves high transmittance. By using such a glass sheet for a circuit board, it is possible to provide a practical high-frequency device such as an electronic device with reduced propagation loss and transmission loss. Furthermore, by using the glass sheet as a window material for a vehicle such as an automobile or a building, electromagnetic waves can be propagated without significant attenuation when a millimeter-wave radar is installed inside the vehicle or when electronic devices are used inside the building. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified as desired without departing from the gist of the present invention. Furthermore, the symbol "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. Furthermore, the symbol "%" indicating the composition of the glass sheet is a value expressed as a mole percentage based on oxides, unless otherwise specified.

[0011] <Glass plate> The glass plate according to this embodiment has a dielectric loss tangent tanδA at 10 GHz and a glass transition temperature Tg°C. When the glass plate is heated to (Tg+50)°C and then cooled to (Tg-150)°C at a rate of 100°C / min, the dielectric loss tangent tanδ100 satisfies the relationship (tanδ100-tanδA)≧0.0004.

[0012] The dielectric loss tangent of a glass sheet (hereinafter sometimes referred to simply as "tan δ") is a value expressed as ε" / ε' using the complex dielectric constant, where ε' is the relative permittivity and ε" is the dielectric loss. The smaller the value of tan δ, the less electromagnetic wave absorption in that frequency band and the higher the transmittance that can be achieved.

[0013] In this specification, the dielectric loss tangent and the relative dielectric constant are values ​​measured at a measurement frequency of 10 GHz according to the method specified in IEC61189-2-721(2015).

[0014] Generally, the value of tan δ can be adjusted by changing the glass composition. However, the present invention has discovered a method for adjusting the value of tan δ without changing the glass composition. This makes it possible to obtain glass with a smaller value of tan δ than conventional glass, even if the composition is the same.

[0015] When manufacturing glass, varying the cooling rate can produce glass with different densities. Specifically, a fast cooling rate results in a low-density (coarse) glass state, while a slow cooling rate results in a high-density (dense) glass state. It has been found that the density of this glass state correlates with the value of tan δ in the high-frequency band.

[0016] In other words, if the density of the glassy state is high and dense, the transmittance of electromagnetic waves in the high frequency band can be increased (absorption can be reduced), and the value of tan δ in the high frequency band becomes small. Note that the high frequency band in this specification usually refers to 3.0 GHz or higher, particularly 3.5 GHz or higher, but the actual verification was carried out at 10 GHz.

[0017] The glass plate according to this embodiment has a smaller value of tan δA in the high frequency band than conventional glass plates of the same composition. This can be determined by the value of (tan δ100 - tan δA) described above. That is, when a glass plate having a dielectric dissipation factor tan δA at 10 GHz is heated to (Tg + 50) °C and then cooled to (Tg - 150) °C at a rate of 100 °C / min, if the value of tan δ100 is larger than the value of tan δA [(tan δ100 - tan δA) > 0], the glass plate is obtained at a cooling rate slower than 100 °C / min, and exhibits a high density and high transmittance.

[0018] Furthermore, by satisfying the relationship that the value of (tanδ100 - tanδA) is 0.0004 or greater [(tanδ100 - tanδA) ≥ 0.0004], the value of tanδA is sufficiently smaller than that of conventional glass sheets of the same composition, and it can be said that the glass exhibits high transmittance to electromagnetic waves in the high frequency band.

[0019] Thus, it is sufficient for the tan δA of the glass plate to satisfy the relationship (tan δ100-tan δA)≧0.0004, but to exhibit even higher transmittance, (tan δ100-tan δA)≧0.0005 is preferred, and (tan δ100-tan δA)≧0.0006 is even more preferred.

[0020] The upper limit of (tan δ100-tan δA) is not particularly limited, but in order to shorten the heat treatment time and improve productivity, it may be (tan δ100-tan δA)≦0.001, (tan δ100-tan δA)≦0.0008, (tan δ100-tan δA)≦0.0007, or (tan δ100-tan δA)≦0.0006.

[0021] The difference in dielectric loss tangent tanδ at 10 GHz between any two locations on the glass plate that are 40 mm or more apart is preferably 0.0005 or less, more preferably 0.0004 or less, and even more preferably 0.0003 or less. When the difference in dielectric loss tangent tanδ is 0.0005 or less, it can be said that the in-plane distribution of the dielectric loss tangent is small, and it can be said that the glass plate is homogeneous with no unevenness in the temperature drop rate, which is preferable. Here, "any two locations that are 40 mm or more apart" refers to any two locations that are 40 mm or more apart on the same plane.

[0022] There is no particular lower limit to the difference in dielectric loss tangent tan δ at 10 GHz between any two points on the glass plate that are 40 mm or more apart, but it may be 0.0001 or more.

[0023] The relative dielectric constant εrA of the glass plate at 10 GHz when the glass plate is heated to (Tg+50)°C and then cooled to (Tg-150)°C at a rate of 100°C / min, where εr100 is the relative dielectric constant at 10 GHz, preferably satisfies the relationship 0.95≦(εr100 / εrA)≦1.05, and the value expressed by (εr100 / εrA) is more preferably 0.98 or more, even more preferably 0.99 or more. Also, it is more preferably 1.03 or less, even more preferably 1.02 or less, and particularly preferably 1.01 or less.

[0024] Unlike the value of tan δA, the relative dielectric constant εr of the resulting glass plate remains almost constant even if the temperature drop rate during production is changed. This allows for reduction of device loss without significantly changing the high-frequency device design.

[0025] The difference in the relative dielectric constant εrA at 10 GHz between any two locations on the glass plate that are 40 mm or more apart is preferably 0.05 or less, more preferably 0.04 or less, and even more preferably 0.03 or less. When the difference in the relative dielectric constant εrA is 0.05 or less, the in-plane distribution of the relative dielectric constant is small, and the temperature drop rate is uniform, resulting in a homogeneous glass plate, which is preferable. The lower limit of the difference in the relative dielectric constant εrA at 10 GHz between any two locations on the glass plate that are 40 mm or more apart is not particularly limited, but may be 0.01 or more.

[0026] A glass plate having such properties can be preferably used as a substrate or window material for high-frequency devices, and the high-frequency device is more preferably a high-frequency device that handles high-frequency signals of 3.0 GHz or higher, particularly 3.5 GHz or higher.

[0027] The glass plate preferably contains 30 to 85% SiO2 in terms of mole percentage based on oxides. As a substrate for a high frequency device, alkali-free glass is more preferable, and as a window material, soda-lime glass is more preferable. Specific preferred glass compositions for each application are as follows:

[0028] When the glass plate is used as a substrate for a high frequency device, it is more preferable that the glass plate has the following composition expressed in mole percentage based on oxides. SiO2 57-70% Al2O3 5-15% B2O3 15-24% Al2O3+B2O320~40% Al2O / (Al2O3+B2O3) 0.1~0.45 MgO 0-10% CaO 0-10% SrO 0-10% BaO 0-10% Li2O 0~5% Na2O 0-5% K2O 0-5%, and R2O (R = alkali metal element) 0-5%

[0029] Each composition will be explained below. SiO2 is a network-forming substance, and a content of 57% or more is preferable because it can improve glass-forming ability and weather resistance and suppress devitrification. The SiO2 content is more preferably 58% or more, even more preferably 60% or more, and even more preferably 61% or more. Also, a SiO2 content of 70% or less is preferable because it can improve the melting property of the glass. The SiO2 content is more preferably 68% or less, even more preferably 66% or less, even more preferably 65% ​​or less, particularly preferably 64% or less, and most preferably 63% or less.

[0030] Al2O3 is a component that is effective in improving weather resistance, improving Young's modulus, suppressing phase separation of glass, and reducing the thermal expansion coefficient. An Al2O3 content of 5% or more is preferable because the effects of including Al2O3 can be fully obtained. An Al2O3 content of 6% or more is more preferable, 7% or more is even more preferable, and 8% or more is even more preferable. An Al2O3 content of 15% or less is also preferable because the melting properties of the glass are good. The content is more preferably 14% or less, more preferably 13% or less, and even more preferably 12% or less.

[0031] B2O3 is a component that improves solubility, and its content is preferably 15% or more. Since it is also a component that can reduce the dielectric loss tangent in the high frequency range, its content is more preferably 16% or more, even more preferably 17% or more, and even more preferably 17.5% or more. On the other hand, from the viewpoint of obtaining good chemical resistance, the B2O3 content is preferably 24% or less, more preferably 23% or less, and even more preferably 22% or less.

[0032] From the viewpoint of the meltability of the glass, the total content of Al2O3 and B2O3 (Al2O3 + B2O3) is more preferably 20% or more, and particularly preferably 25% or more. From the viewpoint of improving the low dielectric loss of the glass sheet while maintaining the meltability of the glass, the total content is preferably 40% or less, more preferably 37% or less, even more preferably 35% or less, and particularly preferably 33% or less.

[0033] MgO is a component that increases Young's modulus without increasing specific gravity, and by increasing the specific modulus of elasticity, it can alleviate problems with deflection and improve fracture toughness, thereby increasing glass strength. Furthermore, MgO also improves solubility, preventing the thermal expansion coefficient from becoming too low. Although MgO is not necessary, if it is included, the content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 1% or more, and even more preferably 2% or more. Furthermore, in order to prevent an increase in the devitrification temperature, the MgO content is preferably 10% or less, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, particularly preferably 6% or less, particularly preferably 5% or less, particularly preferably 4% or less, and most preferably 3% or less.

[0034] Among alkaline earth metals, CaO is the second most important component in increasing the specific modulus after MgO and does not excessively lower the strain point. It also improves solubility, similar to MgO. Furthermore, compared to MgO, CaO is less likely to increase the devitrification temperature. CaO need not be present, but if present, its content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, even more preferably 1% or more, and particularly preferably 2% or more. To prevent devitrification during glass production by preventing the average thermal expansion coefficient from becoming too high and by suppressing an increase in the devitrification temperature, its content is preferably 10% or less, more preferably 8% or less, even more preferably 7% or less, even more preferably 6% or less, especially preferably 5% or less, particularly preferably 4% or less, and particularly preferably 3% or less.

[0035] SrO is a component that improves the meltability without increasing the devitrification temperature of the glass. SrO need not be contained, but if contained, it is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, even more preferably 1% or more, and particularly preferably 2% or more. Furthermore, in order to prevent the specific gravity from becoming too high and the average thermal expansion coefficient from becoming too high, the SrO content is preferably 10% or less, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, particularly preferably 6% or less, particularly preferably 5% or less, especially preferably 4% or less, particularly preferably 3% or less, and most preferably 2.5% or less.

[0036] BaO is a component that improves the meltability without increasing the devitrification temperature of the glass. BaO does not need to be contained, but if it is contained, it is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 1% or more, and particularly preferably 2% or more. Furthermore, since the specific gravity increases, the Young's modulus decreases, the relative dielectric constant increases, and the average thermal expansion coefficient becomes too large, the content is preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, and even more preferably 3% or less.

[0037] ZnO is a component that improves chemical resistance, but it is prone to phase separation and may increase the devitrification temperature. Therefore, the ZnO content is preferably 0.1% or less, more preferably 0.05% or less, even more preferably 0.03% or less, even more preferably 0.01% or less, and particularly preferably substantially free. Substantially free of ZnO means, for example, less than 0.01%.

[0038] The molar ratio represented by {Al2O3 / (Al2O3+B2O3)} is preferably 0.1 or more from the viewpoints of improving acid resistance, suppressing phase separation, and producing a glass with excellent uniformity. Furthermore, from the viewpoint of improving Young's modulus, the molar ratio is more preferably 0.3 or more, even more preferably 0.33 or more, even more preferably 0.35 or more, and particularly preferably 0.38 or more. Furthermore, from the viewpoint of reducing dielectric loss in the high frequency range of 10 GHz or more, preferably above 30 GHz, the molar ratio is preferably 0.45 or less, more preferably 0.4 or less, even more preferably 0.35 or less, and even more preferably 0.3 or less.

[0039] When the contents of Al2O3, MgO, CaO, SrO, and BaO, expressed as mole percentages on an oxide basis, are [Al2O3], [MgO], [CaO], [SrO], and [BaO], respectively, the value expressed by {[Al2O3]-([MgO]+[CaO]+[SrO]+[BaO])} is preferably greater than -3, more preferably -2 or greater, even more preferably -1 or greater, and particularly preferably -0.5 or greater, from the viewpoint of acid resistance. Furthermore, from the viewpoint of suppressing devitrification of the glass, the value expressed by {[Al2O3]-([MgO]+[CaO]+[SrO]+[BaO])} is preferably less than 2, more preferably 1.5 or less, even more preferably 1.0 or less, and particularly preferably 0.5 or less.

[0040] The molar ratio of the contents represented by {(SrO+BaO) / RO} is preferably 0.64 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and particularly preferably 0.8 or more, from the viewpoints of lowering the surface devitrification temperature and improving the productivity of the glass. Furthermore, since the raw materials for SrO and BaO are expensive, the molar ratio is preferably 0.85 or less, more preferably 0.8 or less, from the viewpoint of reducing the raw material costs. Here, RO represents the total amount of MgO, CaO, SrO, and BaO.

[0041] R2O represents the total amount of alkali metal oxides. Examples of alkali metal oxides include Li2O, Na2O, K2O, Rb2O, and Cs2O. Of the alkali metal oxides, Rb2O and Cs2O are rarely contained in glass, so R2O usually refers to the total content of Li2O, Na2O, and K2O (Li2O + Na2O + K2O).

[0042] Although alkali metal oxides are not necessarily contained, they do not require excessive raw material purification, and they can achieve practical glass meltability and glass sheet productivity, while also adjusting the thermal expansion coefficient of the glass sheet. Therefore, when they are contained, the total (RO) content is preferably 0.001% or more, more preferably 0.002% or more, even more preferably 0.003% or more, and particularly preferably 0.005% or more. Furthermore, in order to improve the low dielectric loss of the glass sheet, the total content is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, even more preferably 0.2% or less, particularly preferably 0.1% or less, and particularly preferably 0.05% or less.

[0043] As alkali metal oxides, the content of Li2O is preferably 0 to 5%, more preferably 0.1% or more, even more preferably 0.2% or more, and more preferably 4% or less, and even more preferably 3% or less. The content of Na2O is preferably 0 to 5%, more preferably 0.1% or more, even more preferably 0.2% or more, and more preferably 4% or less, and even more preferably 3% or less. The content of K2O is preferably 0 to 5%, more preferably 0.1% or more, even more preferably 0.2% or more, and more preferably 4% or less, and even more preferably 3% or less.

[0044] In addition to the above, Fe may be contained to reduce the resistance in the melting temperature range, for example, the resistance at 1500°C. When Fe is contained, the content is preferably 0.01% or more, and more preferably 0.05% or more, calculated as Fe2O3. However, if the Fe content is too high, the transmittance in the visible range may decrease, so the Fe content is preferably 1% or less, more preferably 0.5% or less, and even more preferably 0.1% or less, calculated as Fe2O3.

[0045] The β-OH value, which is an index of the water content in glass, is set to 0.05 mm because the resistance value is low in the temperature range where glass raw materials are melted, for example, around 1500 ° C, which is suitable for melting glass by electrical heating. -1 More than 0.1mm is preferable. -1 More than 0.2 mm is more preferable. -1 More preferably, 0.3 mm or more -1 In order to reduce bubble defects in the glass, the β-OH value is preferably 1.0 mm or more. -1 Less than 0.8mm is preferable -1 Less than 0.6mm is preferable. -1 Less than 0.5 mm is more preferable. -1 The following are particularly preferred: In this specification, the β-OH value is determined by measuring the absorbance of a glass sample at a wavelength of 2.75 to 2.95 μm, and determining the maximum absorbance value β max The value was calculated by dividing by the thickness (mm) of the sample.

[0046] In order to improve the clarity of the glass sheet, the glass may contain at least one component selected from the group consisting of SnO2, Cl, and SO3. The total content of these components (SnO2 + Cl + SO3) may be 0.01 to 1.0 mass% expressed as mass percentage when the total content of SiO2, Al2O3, RO, and R2O (SiO2 + Al2O3 + RO + R2O) is taken as 100% expressed as mass percentage on an oxide basis. The total content is preferably 0.80 mass% or less, more preferably 0.50 mass% or less, and even more preferably 0.30 mass% or less. The total content is preferably 0.02 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.10 mass% or more.

[0047] To improve the acid resistance of the glass, the glass may contain at least one component (hereinafter referred to as "trace component") selected from the group consisting of Sc2O3, TiO2, ZnO2, Ga2O3, GeO2, Y2O3, ZrO2, Nb2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3, and Lu2O3. However, if the content of the trace component is too high, the glass becomes less uniform and phase separation becomes more likely. Therefore, the total content of the trace components, expressed as mole percentages based on oxides, is limited to 1.0% or less. The glass may contain only one or more of the above-mentioned trace components.

[0048] F may be contained for the purposes of improving solubility, lowering the strain point, lowering the glass transition temperature, lowering the annealing point, etc. However, in order to prevent an increase in bubble defects in the glass, the content is preferably 1 mass% or less expressed as a mass percentage when the total content of SiO2, Al2O3, RO, and R2O (SiO2 + Al2O3 + RO + R2O) is taken as 100% expressed as a mass percentage on an oxide basis.

[0049] When the glass plate is used as a window material, it is more preferable that the composition be as follows, expressed in mole percentage based on oxides. SiO2 55-80% Al2O30-15% SiO2+Al2O355~90% B2O3 0-15% MgO 0-20% CaO 0-20% SrO 0-15% BaO 0-15% MgO+CaO 0~30% MgO+CaO+SrO+BaO 0~30% Li2O 0~20% Na2O 0-20% K2O 0-20%, and R2O (R = alkali metal element) 0-20%

[0050] Each composition will be explained below. SiO2 and Al2O3 are components that contribute to improving Young's modulus, making it easier to ensure the strength required for window materials for architectural and automotive applications. In order to ensure weather resistance and prevent thermal cracking due to an excessively large average linear expansion coefficient, the SiO content is preferably 55% or more, more preferably 57% or more, even more preferably 60% or more, even more preferably 63% or more, particularly preferably 65% ​​or more, particularly preferably 68% or more, and most preferably 70% or more. In order to prevent an increase in viscosity during glass melting and to facilitate glass production, the SiO content is preferably 80% or less, more preferably 78% or less, even more preferably 75% or less, and most preferably 74% or less.

[0051] Al2O3 is a component that ensures weather resistance and prevents thermal cracking due to an excessively large average linear expansion coefficient. Al2O3 does not have to be contained, but if it is contained, it is preferably 0.01% or more, more preferably 0.05% or more, and even more preferably 0.1% or more. It also prevents an increase in viscosity during glass melting and prevents the glass viscosity from increasing to 10%. 2 The temperature at which the glass viscosity becomes 10 dPa·s (hereinafter referred to as T2) 4 In order to facilitate the production of glass by keeping the temperature at which the viscosity becomes dPa s (hereinafter referred to as T4) low, and to improve the radio wave transmission properties, the content is preferably 15% or less, more preferably 10% or less, even more preferably 5% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0052] The total content of SiO2 and Al2O3 (SiO2 + Al2O3) is preferably 55 to 90% in order to obtain good radio wave transmittance. Furthermore, in order to ensure weather resistance and prevent the average linear expansion coefficient from becoming too large, the total content is more preferably 57% or more, even more preferably 60% or more, even more preferably 65% ​​or more, particularly preferably 70% or more, and most preferably 72% or more. Furthermore, in order to maintain low T2 and T4 and facilitate glass production, the total content is more preferably 85% or less, even more preferably 80% or less, even more preferably 78% or less, and particularly preferably 75% or less.

[0053] B2O3 is a component that improves meltability and glass strength, and also increases radio wave transmittance. However, it can also lead to deterioration of glass quality by volatilizing alkali elements during melting and molding. In addition, excessive B2O3 content reduces the average linear expansion coefficient, making physical strengthening difficult. Therefore, the B2O3 content is preferably 15% or less, more preferably 10% or less, even more preferably 8% or less, even more preferably 5% or less, particularly preferably 3% or less, particularly preferably 1% or less, and most preferably substantially free. Here, "substantially free" means that B2O3 is not included except when mixed in as an unavoidable impurity.

[0054] MgO is a component that promotes the melting of glass raw materials and improves weather resistance. On the other hand, in order to prevent devitrification and increase radio wave transmittance, the MgO content is preferably 20% or less, more preferably 15% or less, even more preferably 8% or less, even more preferably 4% or less, particularly preferably 1% or less, and most preferably 0.5% or less, and may not be contained at all.

[0055] CaO, SrO and BaO are components that can reduce the dielectric loss tangent of the glass and also improve the melting property of the glass, and one or more of these may be contained.

[0056] CaO does not have to be contained, but if contained, the dielectric loss of the glass is reduced, which in turn improves the radio wave transmittance, and the solubility can also be improved (reduced T2 and T4), so its content is preferably 3% or more, more preferably 6% or more, even more preferably 8% or more, even more preferably 10% or more, and particularly preferably 11% or more. Also, in order to avoid an increase in the specific gravity of the glass and to maintain low brittleness and strength, its content is preferably 20% or less, and in order to further reduce brittleness, it is more preferably 15% or less, even more preferably 14% or less, even more preferably 13% or less, and particularly preferably 12% or less.

[0057] In order to avoid an increase in the specific gravity of the glass and maintain low brittleness and strength, the SrO content is preferably 15% or less, more preferably 8% or less, even more preferably 3% or less, and even more preferably 1% or less, and it is particularly preferable that SrO is substantially not contained. Here, "substantially not containing SrO" means that SrO is not contained except when mixed in as an unavoidable impurity.

[0058] In order to avoid an increase in the specific gravity of the glass and maintain low brittleness and strength, the content of BaO is preferably 15% or less, more preferably 5% or less, even more preferably 3% or less, even more preferably 2% or less, particularly preferably 1% or less, and most preferably substantially free of BaO. Here, "substantially free of BaO" means that BaO is not contained except when mixed in as an unavoidable impurity.

[0059] The total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) may be 0% (none), but from the viewpoints of lowering the glass viscosity during production, lowering T2 and T4, or increasing the Young's modulus, it is preferably more than 0%, more preferably 0.5% or more, even more preferably 5% or more, even more preferably 8% or more, particularly preferably 10% or more, and most preferably 11% or more. Also, from the viewpoint of improving weather resistance, the total content is preferably 30% or less, more preferably 17% or less, even more preferably 16% or less, even more preferably 15% or less, particularly preferably 14% or less, and most preferably 13% or less.

[0060] Furthermore, in order to prevent devitrification during glass melting or molding, which would lead to deterioration in glass quality, the total content of MgO and CaO (MgO+CaO) is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, even more preferably 15% or less, and particularly preferably 13% or less. Although the total content may be 0% (none), in order to prevent the glass viscosity from becoming too high during melting and molding, which would make production difficult, the total content is preferably 1% or more, more preferably 2% or more, even more preferably 5% or more, even more preferably 8% or more, and particularly preferably 10% or more.

[0061] Li2O is a component that improves the meltability of glass and also facilitates increasing the Young's modulus, contributing to improving the strength of the glass. Although Li2O is not necessary, its inclusion enables chemical strengthening and may also be effective in increasing radio wave transmittance. Therefore, when Li2O is contained, its content is preferably 0.1% or more, more preferably 1% or more, even more preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. Furthermore, since devitrification or phase separation may occur during glass production, making production difficult, its content is preferably 20% or less, more preferably 16% or less, even more preferably 12% or less, even more preferably 8% or less, particularly preferably 7% or less, and most preferably 6.5% or less.

[0062] Na2O and K2O are components that improve the meltability of glass, and by including at least one of them in an amount of 0.1% or more, T2 can be easily controlled to 1750°C or less and T4 to 1350°C or less. Furthermore, if the total content of Na2O and K2O is low, the average linear expansion coefficient cannot be increased, which may prevent thermal strengthening. Furthermore, by including both Na2O and K2O, weather resistance can be improved while maintaining meltability. Furthermore, it may also be effective in increasing radio wave transmittance.

[0063] Although Na2O does not have to be contained, its inclusion enables chemical strengthening in addition to the above, so its content is preferably 0.1% or more, more preferably 1% or more, even more preferably 3% or more, even more preferably 5% or more, and particularly preferably 6% or more. Also, in order to prevent the average linear expansion coefficient from becoming too large and making the steel more susceptible to thermal cracking, its content is preferably 20% or less, more preferably 16% or less, even more preferably 14% or less, even more preferably 12% or less, particularly preferably 10% or less, and most preferably 8% or less.

[0064] Although KO is not necessarily contained, its inclusion provides the above-mentioned effects, and therefore its content is preferably 0.1% or more, more preferably 0.9% or more, even more preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. Furthermore, in order to prevent the average linear expansion coefficient from becoming too large, which would make the material more susceptible to thermal cracking, and to prevent a decrease in weather resistance, its content is preferably 20% or less, more preferably 16% or less, even more preferably 14% or less, even more preferably 12% or less, particularly preferably 10% or less, and most preferably 8% or less. Furthermore, from the viewpoint of radio wave transmittance, a high radio wave transmittance can be obtained by keeping the KO content within the above range.

[0065] By setting the contents of NaO and KO within the above ranges, the average thermal expansion coefficient can be adjusted to a desired value, making the material suitable for use as a window material that is compatible with other components such as black ceramics and interlayer films.

[0066] R2O represents the total amount of alkali metal oxides. Among alkali metal oxides, Rb2O and Cs2O are rarely contained in glass, so R2O usually refers to the total content of Li2O, Na2O, and K2O (Li2O + Na2O + K2O).

[0067] Although alkali metal oxides are not necessarily contained, they are components that reduce the glass viscosity during glass production and lower T2 and T4. Therefore, their total content is preferably more than 0%, more preferably 1% or more, even more preferably 5% or more, even more preferably 6% or more, particularly preferably 8% or more, especially preferably 10% or more, particularly preferably 11% or more, and particularly preferably 12% or more. Furthermore, from the viewpoint of improving weather resistance, their total content is preferably 20% or less, more preferably 19% or less, even more preferably 18.5% or less, even more preferably 18.0% or less, particularly preferably 17.5% or less, and most preferably 17.0% or less.

[0068] When an alkali metal oxide is contained, Na2O is preferably contained, and the molar ratio (Na2O / R2O) is preferably 0.01 or more and more preferably 0.98 or less in order to fully obtain the effect of lowering the dielectric tangent. The molar ratio is more preferably 0.05 or more, even more preferably 0.1 or more, particularly preferably 0.2 or more, particularly preferably 0.3 or more, and most preferably 0.4 or more. The molar ratio is more preferably 0.8 or less, even more preferably 0.7 or less, particularly preferably 0.6 or less, and most preferably 0.55 or less.

[0069] When an alkali metal oxide is contained, it is also preferable to contain KO, and the molar ratio represented by (KO / RO) is more preferably 0.01 or more and more preferably 0.98 or less in order to fully obtain the effect of increasing radio wave transmittance. The molar ratio is more preferably 0.05 or more, even more preferably 0.1 or more, particularly preferably 0.2 or more, particularly preferably 0.3 or more, and most preferably 0.4 or more. The molar ratio is more preferably 0.8 or less, even more preferably 0.6 or less, and particularly preferably 0.55 or less.

[0070] The product of the total content of alkali metal oxides (RO, %) and the MgO content (%) (RO × MgO, %) 2 ) is preferably low in order to increase radio wave transmittance. (R2O × MgO) is 100% 2Less than 80% is preferred 2 The following is more preferable, 66% 2 Even better, 60% 2 The following is even more preferable: 50% 2 The following is especially preferred: 40% 2 The following is especially preferred: 30% 2 In addition, from the viewpoint of improving the productivity of glass, 1% or less is most preferable. 2 More than 3% is preferable 2 More than 5% is preferable. 2 The following is even more preferred:

[0071] ZrO2 is a component that reduces the viscosity of glass during melting, promotes melting, and improves heat resistance and chemical durability. On the other hand, if the content is too high, the liquidus temperature may rise. Therefore, the ZrO2 content is preferably 5% or less, more preferably 2.5% or less, even more preferably 2% or less, more preferably 1% or less, particularly preferably 0.5% or less, and particularly preferably substantially not contained. Here, "substantially not contained" means that ZrO2 is not contained except when mixed in as an unavoidable impurity.

[0072] Of the above components, the total content represented by (SiO2 + Al2O + MgO + CaO + SrO + BaO + Li2O + Na2O + KO) is preferably 85% or more, more preferably 88% or more, even more preferably 90% or more, even more preferably 92% or more, especially preferably 95% or more, particularly preferably 98% or more, and most preferably 99.5% or more, because this allows the glass plate to be produced from readily available glass raw materials and also makes it easier to ensure the weather resistance of the glass plate. Furthermore, the total content may be 100%, but is more preferably 99.9% or less in consideration of the addition of colorants, fining agents, etc. to the glass plate.

[0073] In order to improve the clarity of the glass sheet, the glass may contain at least one component selected from the group consisting of SnO2, Cl, and SO3. The total content of these components (SnO2 + Cl + SO3) may be 0.01 to 1.0 mass% expressed as mass percentage when the total content of the main components SiO2, Al2O3, RO, and RO (SiO2 + Al2O3 + RO + RO) expressed as mass percentage on an oxide basis is 100%. The total content is preferably 0.80 mass% or less, more preferably 0.50 mass% or less, and even more preferably 0.30 mass% or less. The total content is preferably 0.02 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.10 mass% or more.

[0074] When a glass plate is used as a substrate for a high-frequency device, the glass plate has the following preferred glass transition temperatures Tg, T2, T4, devitrification temperature, Young's modulus, acid resistance, alkali resistance, expansion coefficient (average expansion coefficient), strain point, density, plate thickness, and main surface area.

[0075] The glass transition temperature Tg is preferably 580°C or higher, more preferably 600°C or higher, from the viewpoint of preventing deformation of the substrate during the manufacturing process of the high-frequency device. Furthermore, from the viewpoint of facilitating the manufacture of the glass plate, it is preferably 750°C or lower, more preferably 720°C or lower. The glass transition temperature Tg is a value measured in accordance with JIS R 3103-3:2001.

[0076] T2 is preferably 1950° C. or lower, more preferably 1700° C. or lower, from the viewpoint of facilitating the production of glass sheets, and is preferably 1500° C. or higher from the viewpoint of reducing convection of molten glass and preventing damage to glass melting equipment.

[0077] T4 is preferably 1350°C or lower, more preferably 1300°C or lower, from the viewpoint of protecting the manufacturing equipment. In addition, T4 is preferably 1100°C or higher, from the viewpoint that if the amount of heat brought into the forming equipment by the glass decreases, it is necessary to increase the amount of heat input into the forming equipment. It should be noted that T2 and T4 are values ​​measured using a rotational high-temperature viscometer.

[0078] The devitrification temperature is preferably 1350°C or lower, and more preferably 1300°C or lower, from the viewpoint that the temperature of the components of the forming equipment can be lowered during the forming of the glass sheet and the life of the components can be extended. The lower limit of the devitrification temperature is not particularly limited, but may be 1000°C or higher, or 1050°C or higher. The devitrification temperature is determined by placing crushed glass particles in a platinum dish, heat-treating the particles for 17 hours in an electric furnace controlled at a constant temperature, and observing the heat-treated sample with an optical microscope. The average value of the maximum temperature at which crystals precipitate on the surface and inside of the glass and the minimum temperature at which crystals do not precipitate is thus obtained.

[0079] The Young's modulus is preferably 50 GPa or more, more preferably 55 GPa or more, in order to suppress the amount of deflection when the glass plate is subjected to the manufacturing process of a high-frequency device. The upper limit of the Young's modulus is not particularly limited, but may be 100 GPa or less. The Young's modulus is a value measured by an ultrasonic pulse Young's modulus measuring device.

[0080] Acid resistance refers to the amount of glass components dissolved per unit surface area when a glass plate is immersed in an acid solution (6 wt% HNO3 + 5 wt% H2SO4, 45°C) for 170 seconds. The amount of dissolved glass components that indicates acid resistance is 0.05 g / cm2 in order to avoid damaging the surface when cleaning the glass surface with an acid solution. 2 Preferably less than 0.03 g / cm 2 The lower limit of the amount of elution is not particularly limited, but is preferably 0.001 g / cm. 2 It may be more than that.

[0081] Alkali resistance refers to the amount of glass components dissolved per unit surface area when a glass plate is immersed in an alkaline aqueous solution (1.2 wt% NaOH, 60°C) for 30 minutes. The amount of dissolved glass components that indicates alkali resistance is 0.10 g / cm2, which is the minimum required to avoid damaging the surface when cleaning the glass surface with an alkaline solution. 2 Preferably less than 0.08 g / cm 2 The lower limit of the amount of elution is not particularly limited, but is preferably 0.001 g / cm. 2 It may be more than that.

[0082] The expansion coefficient is the average thermal expansion coefficient measured by a thermal dilatometer in the temperature range of 50 to 350°C. The average thermal expansion coefficient is set to 20 x 10 in order to more appropriately adjust the difference in thermal expansion coefficient with other materials when constructing a semiconductor package or the like as a high-frequency device. -7 (K -1 ) or more is preferable, and 25 × 10 -7 (K -1 ) or more is more preferable. In addition, the average thermal expansion coefficient is 60×10 -7 (K -1 ) or less is preferable, 50 × 10 -7 (K -1 ) or less is more preferable.

[0083] The strain point is preferably 500° C. or higher, more preferably 550° C. or higher, from the viewpoint of heat resistance. Also, from the viewpoint of ease of relaxation, it is preferably 800° C. or lower. The strain point is a value measured in accordance with JIS R 3103-2 (2001).

[0084] The density is 2.8g / cm to make it lightweight. 3 The lower limit of the density is not particularly limited, but is preferably 2.0 g / cm 2 The density is a value measured by Archimedes' method.

[0085] The plate thickness is preferably 0.05 mm or more, more preferably 0.1 mm or more, and even more preferably 0.3 mm or more in terms of ensuring the strength of the substrate, and is preferably 2.0 mm or less, more preferably 1.5 mm or less, even more preferably 1.0 mm or less, even more preferably 0.7 mm or less, and particularly preferably 0.5 mm or less in terms of reducing thickness, size, improving production efficiency, etc.

[0086] When a glass plate is used as a substrate for a high-frequency device, the area of ​​the main surface of the glass plate is 80 cm 2 More than 350cm is preferable. 2 More than 500cm is preferable. 2 More preferably, 1000 cm 2 More preferably, 1500 cm 2More than 2000cm is more preferable, and 2 More than 2500cm 2 More than 3000cm 2 More than 4000cm 2 More than 6000cm 2 More than 8000cm 2 More than 12000cm 2 More than 16000cm 2 More than 20000cm 2 More than 25000cm 2 On the other hand, the area of ​​the main surface of the substrate is usually 5,000,000 cm 2 Even with such an area, the in-plane distribution of the dielectric loss tangent is small, and the glass plate is homogeneous. Therefore, it can be suitably used for manufacturing high-frequency devices over a large area, which has not been possible with conventional methods, and for windows that transmit high frequencies. The area of ​​the main surface of the substrate is more preferably 100,000 cm. 2 Less than or equal to 80,000 cm 2 or less, more preferably 60,000 cm 2 Below 50000 cm, particularly preferably 2 More preferably, 40,000 cm 2 Below 30000 cm, most preferably 2 The following is the result.

[0087] When the glass sheet is used as a window material, the glass transition temperatures Tg, T2, T4, devitrification temperature, Young's modulus, acid resistance, alkali resistance, expansion coefficient (average expansion coefficient), strain point, density, sheet thickness, and area of ​​the main surface of the glass sheet are preferably as follows: The methods for measuring each physical property are the same as those for the case of use as the above-mentioned high-frequency device substrate.

[0088] The glass transition temperature Tg is preferably 500° C. or higher, more preferably 520° C. or higher, from the viewpoint of bending the glass, and is preferably 620° C. or lower, more preferably 600° C. or lower, from the viewpoint of air-cooling tempering.

[0089] T2 is preferably 1550° C. or lower, more preferably 1480° C. or lower, from the viewpoint of facilitating the production of glass sheets, and is preferably 1250° C. or higher from the viewpoint of reducing convection of molten glass and preventing damage to glass melting equipment.

[0090] T4 is preferably 1200°C or lower, more preferably 1100°C or lower, from the viewpoint of protecting the manufacturing equipment. In addition, T4 is preferably 900°C or higher, from the viewpoint that if the amount of heat brought into the forming equipment by the glass decreases, it is necessary to increase the amount of heat input into the forming equipment.

[0091] The devitrification temperature is preferably 1100°C or lower, and more preferably 1000°C or lower, from the viewpoint that the temperature of components in the forming equipment can be lowered during forming of the glass sheet and the life of the components can be extended. The lower limit of the devitrification temperature is not particularly limited, but may be 900°C or higher.

[0092] The Young's modulus is preferably 50 GPa or more, more preferably 55 GPa or more, in order to suppress the amount of deflection. The upper limit of the Young's modulus is not particularly limited, but may be 100 GPa or less.

[0093] Acid resistance is achieved by limiting the elution amount shown above to 0.1 g / cm3 in order to prevent the surface from being damaged when cleaning the glass surface with an acid solution. 2 Preferably less than 0.05 g / cm 2 The lower limit of the amount of elution is not particularly limited, but is preferably 0.001 g / cm. 2 It may be more than that.

[0094] Alkali resistance is achieved by limiting the amount of elution shown above to 0.20 g / cm3 in order to prevent the surface from being roughened when cleaning the glass surface with an alkaline solution. 2 Preferably less than 0.10 g / cm 2 The lower limit of the amount of elution is not particularly limited, but is preferably 0.001 g / cm. 2 It may be more than that.

[0095] As mentioned above, the average thermal expansion coefficient in the temperature range of 50 to 350°C is used. The average thermal expansion coefficient is set to 60 x 10 -7 (K -1 ) or more is preferable, and 70 × 10 -7 (K -1 ) or more is more preferable. In addition, if the average thermal expansion coefficient is too large, the material will be vulnerable to thermal shock. -7 (K -1 ) or less is preferable, 110 × 10 -7 (K -1 ) or less is preferred.

[0096] The strain point is preferably 450° C. or higher, more preferably 500° C. or higher, from the viewpoint of heat resistance. Also, from the viewpoint of ease of relaxation, it is preferably 700° C. or lower. The strain point is a value measured in accordance with JIS R 3103-2 (2001).

[0097] The density is set at 2.8 g / cm because the larger the density, the heavier it becomes and the more difficult it becomes to handle when transporting. 3 The lower limit of the density is not particularly limited, but is preferably 2.0 g / cm 2 It may be more than that.

[0098] The thickness is preferably 1.0 mm or more, more preferably 1.5 mm or more, in order to ensure the rigidity required for the window material, and is preferably 6.0 mm or less, more preferably 5.0 mm or less, in order to reduce the weight.

[0099] When glass sheets are used as window materials, the area of ​​the main surface of the glass sheet is 350 cm 2 More than 500cm is preferable. 2 More preferably, 1000 cm 2 More preferably, 1500 cm 2 More than 2000cm is more preferable, and 2 More than 2500cm 2 More than 3000cm 2 More than 4000cm 2 More than 6000cm 2 More than 8000cm 2 More than 12000cm2 More than 16000cm 2 More than 20000cm 2 More than 25000cm 2 The above is particularly preferred.

[0100] On the other hand, the area of ​​the main surface of the window material is usually 6,000,000 cm 2 Even with such a large area, the in-plane distribution of the dielectric loss tangent is small, and the glass plate is homogeneous. Therefore, it can be suitably used for manufacturing large-area high-frequency devices and windows that transmit high frequencies, which were previously unrealizable. To ensure the homogeneity of the glass plate, it is better to keep the area of ​​the main surface as small as possible, so the area of ​​the main surface of the window material should preferably be 100,000 cm 2 Less than or equal to 80,000 cm 2 or less, more preferably 60,000 cm 2 Below 50000 cm, particularly preferably 2 More preferably, 40,000 cm 2 Below 30000 cm, most preferably 2 The following is the result.

[0101] It is preferable that both tan δA and εrA are small. This makes it possible to apply the film to large-area high-frequency devices and windows that transmit high frequencies, which were previously unrealizable. Tan δA is preferably 0.009 or less, more preferably 0.008 or less, 0.007 or less, 0.006 or less, 0.005 or less, even more preferably 0.004 or less, particularly preferably 0.0035 or less, even more preferably 0.003 or less, and most preferably 0.0025 or less.

[0102] Although there is no particular restriction on the lower limit of tan δA, from the viewpoint of the practicality of manufacturing glass sheets, it is 0.0001 or more, more preferably 0.0004 or more, even more preferably 0.0006 or more, even more preferably 0.0008 or more, and most preferably 0.001 or more. εrA is preferably 6.8 or less, more preferably 6.5 or less, 6.0 or less, 5.5 or less, 5.2 or less, 4.9 or less, even more preferably 4.7 or less, particularly preferably 4.5 or less, even more preferably 4.4 or less, and most preferably 4.3 or less.

[0103] The lower limit of εrA is not particularly limited, but from the viewpoint of the practicality of producing glass plates, it is 3.5 or more, more preferably 3.6 or more, even more preferably 3.7 or more, particularly preferably 3.8 or more, even more preferably 3.9 or more, and most preferably 4.0 or more.

[0104] <Glass plate manufacturing method> The method for producing a glass plate according to this embodiment includes, in this order, a melting and forming step of melting glass raw materials to form molten glass into a plate; a cooling step of cooling the molten glass formed into the plate to a temperature equal to or lower than the glass transition temperature Tg (°C) by (Tg-300)°C to obtain a raw glass plate; and a heat treatment step of heating the obtained raw glass plate from a temperature equal to or lower than (Tg-300)°C to a range of (Tg-100)°C to (Tg+50)°C without exceeding (Tg+50)°C, and then cooling it again to (Tg-300)°C or lower. The heat treatment step is carried out once, twice, or three or more times. One heat treatment step is the period from when the temperature of the glass plate exceeds (Tg-300)°C, passes through a maximum temperature Temax°C in the range of (Tg-100)°C to (Tg+50)°C, and then drops back to (Tg-300)°C or below. During the entire heat treatment process, the total time during which the temperature of the glass plate is in the range of (Tg-100)°C to (Tg+50)°C is equal to or longer than K (minutes) as expressed by the following formula (1), where Tmax°C is the maximum temperature of the glass plate during the entire heat treatment process. In each heat treatment step, when the time from the last time when the temperature starts to decrease from the maximum temperature Temax °C to the time when the temperature finally passes (Tg-110) °C is defined as t1 (minutes), the following formula (2) is satisfied. K=[{(Tg+50)-Tmax} / 10]+15 Formula (1) {Temax-(Tg-110)} / t1≦10 Equation (2) This gives the glass plate described above in <Glass Plate>.

[0105] (Melting and molding process) In the melting and forming step, the molten glass obtained by melting the glass raw materials is formed into a sheet shape, and any conventionally known method can be used, and is not particularly limited. An example of such a method is shown below.

[0106] Glass raw materials are prepared so as to have the composition of the target glass sheet, and the raw materials are continuously charged into a melting furnace and heated preferably to about 1450 to 1750° C. to obtain molten glass.

[0107] The raw materials can also be oxides, carbonates, nitrates, sulfates, hydroxides, chlorides, and other halides. If the molten glass comes into contact with platinum during the melting or fining process, minute platinum particles may dissolve into the molten glass and become mixed into the resulting glass sheet as foreign matter. However, the use of a nitrate raw material has the effect of preventing the formation of platinum foreign matter.

[0108] As the nitrate, strontium nitrate, barium nitrate, magnesium nitrate, calcium nitrate, etc. can be used. It is more preferable to use strontium nitrate. The particle size of the raw material can be appropriately selected from raw materials with a large particle size of several hundred μm so that no undissolved residue remains, to raw materials with a small particle size of about several μm so that no scattering occurs during raw material transportation and no aggregation occurs as secondary particles. Granules can also be used. The moisture content of the raw material can also be appropriately adjusted to prevent scattering of the raw material. The oxidation-reduction degree of β-OH and Fe (redox {Fe 2+ / (Fe 2+ +Fe 3+ )}) and other dissolution conditions can also be adjusted appropriately.

[0109] Next, a fining step may be performed to remove bubbles from the obtained molten glass. The fining step may be performed by applying a degassing method under reduced pressure, or by heating to a temperature higher than the melting temperature of the raw materials. SO3 or SnO2 may be used as a fining agent.

[0110] The SO3 source is preferably a sulfate of at least one element selected from Al, Li, Na, K, Mg, Ca, Sr, and Ba. Alkali metal sulfates are more preferred, with Na2SO4 being particularly preferred due to its significant bubble-enhancing effect and good initial solubility. Alternatively, alkaline earth metal sulfates may be used, with CaSO4·2H2O, SrSO4, and BaSO4 being more preferred due to their significant bubble-enhancing effect.

[0111] As a fining agent in the degassing method under reduced pressure, a halogen such as Cl or F is preferably used. The Cl source is preferably a chloride of at least one element selected from Al, Mg, Ca, Sr, and Ba, more preferably an alkaline earth metal chloride, and among these, SrCl2·6H2O and BaCl2·2H2O are particularly preferred because they have a significant effect of increasing bubble size and are less prone to deliquescence.

[0112] The F source is preferably a fluoride of at least one element selected from Al, Na, K, Mg, Ca, Sr, and Ba, more preferably an alkaline earth metal fluoride, and among these, CaF2 is more preferred because it has a significant effect of increasing the solubility of the glass raw materials.

[0113] Tin compounds, such as SnO2, generate O2 gas in molten glass. In molten glass, SnO2 is reduced to SnO at temperatures above 1450°C, generating O2 gas and causing bubbles to grow larger. When glass sheets are manufactured, glass raw materials are heated to approximately 1450 to 1750°C to melt them, which effectively increases the size of bubbles in the molten glass.

[0114] Next, the molten glass, preferably the molten glass from which bubbles have been removed in the refining step, is subjected to a forming step in which the molten glass is formed into a sheet to obtain a glass ribbon.

[0115] As the forming step, a known method for forming glass into a plate can be applied, such as a float method in which molten glass is poured onto a molten metal such as tin to form a plate and obtain a glass ribbon, an overflow downdraw method (fusion method) in which molten glass is made to flow downward from a trough-shaped member, or a slit downdraw method in which molten glass is made to flow down through a slit. The molten glass may be subjected to the subsequent cooling step as it is without being formed into a plate.

[0116] (Temperature cooling process) The molten glass obtained in the forming step is cooled to a temperature of (Tg-300)°C or less relative to the glass transition temperature Tg (°C) to obtain a raw glass plate. The average cooling rate is not particularly limited, and any average cooling rate can be used. However, for example, to prevent devitrification of the glass, a rate of 10°C / min or more is preferred, and 40°C / min or more is more preferred. Furthermore, to avoid generating distortion in the glass during the cooling step, a rate of 1000°C / min or less is preferred, and 100°C / min or less is more preferred. Furthermore, the average cooling rate from (Tg+50)°C to (Tg-100)°C is preferably more than 10°C / min, and more preferably 15°C / min or more.

[0117] The average cooling rate refers to an average value determined from the refractive index when the cooling rates at the center and edge of the glass sheet are different. The cooling rates at the center and edge can be measured from the refractive index.

[0118] (Heat treatment process) After the temperature-lowering step, the obtained raw glass plate is subjected to a heat treatment in which the temperature is raised from the temperature of (Tg-300)° C. or lower to a range of (Tg-100)° C. to (Tg+50)° C. without exceeding (Tg+50)° C., and then lowered to (Tg-300)° C. or lower. This heat treatment step may be carried out once, twice, or three or more times.

[0119] One heat treatment process lasts from when the temperature of the glass plate exceeds (Tg-300)°C, passes through a maximum temperature Temax°C in the range of (Tg-100)°C to (Tg+50)°C, and then drops back to below (Tg-300)°C.

[0120] In one heat treatment step, the rate of temperature increase from exceeding (Tg-300)°C until the temperature reaches the range of (Tg-100)°C to (Tg+50)°C is not particularly limited. Furthermore, the temperature may be repeatedly increased and decreased, or may be maintained at a constant temperature until the temperature reaches the range of (Tg-100)°C to (Tg+50)°C.

[0121] During the entire heat treatment process, the total time during which the temperature of the glass plate is within the range of (Tg-100)°C to (Tg+50)°C is equal to or longer than K (minutes) as expressed by the following formula (1), where Tmax°C is the maximum temperature of the glass plate during the entire heat treatment process. K=[{(Tg+50)-Tmax} / 10]+15 Formula (1)

[0122] Here, when the heat treatment process is performed two or more times, the total time during which the temperature of the glass plate is within the range of (Tg-100)°C to (Tg+50)°C refers to the total time during the first heat treatment process during which the temperature of the glass plate is within the range of (Tg-100)°C to (Tg+50)°C and the time during the second and subsequent heat treatment processes. If the total time during which the temperature of the glass plate is within the range of (Tg-100)°C to (Tg+50)°C is K (minutes) or more, the radio wave transmittance is improved.

[0123] The total time during which the temperature of the glass plate is in the range of (Tg-100)°C to (Tg+50)°C is preferably (K+5) minutes or more, more preferably (K+10) minutes or more. There is no particular upper limit, but to improve productivity, it is preferably (K+60) minutes or less, more preferably (K+45) minutes or less, and even more preferably (K+30) minutes or less.

[0124] The temperature profile of the glass plate is not particularly limited as long as the total time within the range of (Tg-100)°C to (Tg+50)°C is K (minutes) or more. That is, during one heat treatment step, the temperature may be repeatedly increased and decreased, for example, by increasing the temperature to the range of (Tg-100)°C to (Tg+50)°C, decreasing the temperature to a temperature above (Tg-300)°C but below (Tg+50)°C, and then increasing the temperature again to the range of (Tg-100)°C to (Tg+50)°C. Alternatively, the temperature may be maintained at a constant value.

[0125] The lower limit of the temperature range is set to (Tg - 100)°C in order to improve radio wave transmittance, but is preferably at least (Tg - 90)°C, and more preferably at least (Tg - 80)°C. The upper limit of the temperature range is set to (Tg + 50)°C in order to prevent deformation of the glass, but is preferably at most (Tg + 40)°C, and more preferably at most (Tg + 35)°C.

[0126] In each heat treatment step, when the time from the last time when the temperature starts to decrease from the maximum temperature Temax°C in each step to the time when the temperature finally passes (Tg-110)°C is defined as t1 (minutes), the following formula (2) is satisfied. Note that when the heat treatment step is performed once, Temax°C and the Tmax°C are the same. When the heat treatment step is performed twice or more times, the highest temperature of the two or more Temax°C is the Tmax°C. {Temax-(Tg-110)} / t1≦10 Equation (2)

[0127] The temperature profile of the glass plate may vary, including the aforementioned heating to the range of (Tg - 100)°C to (Tg + 50)°C, followed by cooling to a temperature above (Tg - 300)°C but below (Tg + 50)°C, and then heating back up to the range of (Tg - 100)°C to (Tg + 50)°C, as well as temperature variations caused by heating and cooling within the range of (Tg - 100)°C to (Tg + 50)°C, and maintaining a constant temperature within the range of (Tg - 100)°C to (Tg + 50)°C.

[0128] In such various temperature profiles, the last time when the temperature starts to decrease from the maximum temperature Temax °C means the time when the maximum temperature Temax °C is reached only once. Also, in the case of reaching it two or more times, it means the time of the last occurrence. Further, in the case of maintaining at the maximum temperature Temax °C for a certain period of time, it means the last time when such maintenance ends.

[0129] The same applies to the time when it last passes through (Tg - 110) °C. That is, after the last time when the temperature starts to decrease from the maximum temperature Temax °C, during the period until the temperature decreases to (Tg - 300) °C or lower, the temperature increase or decrease may be repeated, or it may be maintained at a constant temperature. When the number of times of passing through (Tg - 110) °C is 1 during the period of decreasing to (Tg - 300) °C or lower, the time when it last passes through (Tg - 110) °C is the time when it passes through (Tg - 110) °C. When the temperature increases again above (Tg - 110) °C after passing through (Tg - 110) °C once and then decreases again, it means the time when it passes through (Tg - 110) °C when finally decreasing. Also, in the case of maintaining at (Tg - 110) °C for a certain period of time, it means the last time when such maintenance ends.

[0130] The temperature profiles in the heat treatment steps other than those described above are not particularly limited.

[0131] In each cycle of the heat treatment step, it is preferable from the viewpoint of shortening the manufacturing process that after the temperature of the glass substrate decreases from the maximum temperature Temax °C and first falls below (Tg - 110) °C, it does not exceed (Tg - 110) °C again.

[0132] Also, in each cycle of the heat treatment step, when any two times between the last time when the temperature starts to decrease from the maximum temperature Temax °C for each cycle and the time when it last passes through (Tg - 110) °C are t2 (minutes) and t3 (minutes) and t2 < t3, the time difference between t2 and t3 is preferably 1 minute or more. And when the temperature of the glass substrate at t2 is Te2 and the temperature of the glass substrate at t3 is Te > 3, it is preferable to satisfy the following formula (3). (Te2-Te3) / (t3-t2)≦10 Equation (3)

[0133] The above formula (3) means that the temperature drop rate at time t1 is not too fast, and satisfying the relationship of formula (3) is preferable because it allows a sufficient heat treatment time to be secured.

[0134] The value represented by (Te2-Te3) / (t3-t2) is more preferably equal to or less than 9, and even more preferably equal to or less than 8. The lower limit is not particularly limited, but may be equal to or greater than 0.1 so as to prevent the time required for producing the glass plate from becoming too long.

[0135] In the final heat treatment step, when the temperature is lowered from the maximum temperature Temax°C to (Tg-300)°C or lower, the average temperature lowering rate at the center of the glass plate is VC (°C / min) and the average temperature lowering rate at the edges is VE (°C / min), so that the resulting glass plate will be homogeneous. The closer the ratio VC / VE is to 1, the better. Specifically, the ratio is preferably 0.8 or higher, more preferably 0.9 or higher, and is preferably 1.2 or lower, more preferably 1.1 or lower, and most preferably 1.

[0136] The raw glass plate whose temperature has been lowered to (Tg-300)°C or lower in the heat treatment step is then lowered to room temperature (for example, to 50°C or lower), thereby obtaining the glass plate according to this embodiment.

[0137] The conditions for cooling to room temperature are not particularly limited, but for example, the average cooling rate from (Tg-300)°C to 50°C is preferably 0.5°C / min or more and 50°C / min or less. Alternatively, natural cooling may be performed without temperature control.

[0138] The method for manufacturing a glass plate is not limited to the above-described embodiment, and any modifications or improvements that can achieve the object of the present invention are included in the present invention.

[0139] For example, when producing a glass plate, the glass may be formed into a plate shape by a press molding method in which molten glass is directly formed into a plate shape. After the glass plate is obtained, any treatment or processing such as air-cooling tempering treatment, chemical tempering treatment, polishing, etc. may be performed.

[0140] In melting and refining glass raw materials, not only a melting tank made of a refractory material but also a crucible made of platinum or an alloy containing platinum as a main component (hereinafter referred to as a "platinum crucible") may be used as the melting tank and / or refining tank.

[0141] In the melting process when using a platinum crucible, raw materials are prepared so as to have the composition of the resulting glass plate, and the platinum crucible containing the raw materials is heated in an electric furnace, preferably to about 1450° C. to 1700° C. A platinum stirrer is then inserted and the mixture is stirred for 1 to 3 hours to obtain molten glass.

[0142] In the forming step in the manufacturing process of a glass plate using a platinum crucible, the molten glass can be poured onto, for example, a carbon plate or into a mold to form a plate or block.

[0143] By using the glass plate thus obtained as a substrate for a high-frequency device, the propagation loss of the high-frequency signal can be reduced and the characteristics of the high-frequency signal, such as quality and strength, can be improved. Therefore, a substrate made of the glass plate can be suitably used for high-frequency devices that handle high-frequency signals of 3.0 GHz or higher, and can also be suitably used for high-frequency devices that handle signals in various high-frequency bands, such as 3.5 GHz or higher, 10 GHz or higher, 30 GHz or higher, and 35 GHz or higher.

[0144] Examples of high-frequency devices include, but are not limited to, high-frequency devices (electronic devices) such as semiconductor devices used in communication devices such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices, surface acoustic wave (SAW) devices, radar components such as radar transceivers, and antenna components such as liquid crystal antennas.

[0145] In addition to the above, the glass sheet is also suitable as a window material for vehicles such as automobiles and buildings. That is, high-frequency devices that handle the above-mentioned high-frequency signals are sometimes installed inside vehicles, such as millimeter-wave radar. They are also often used inside buildings, such as communication equipment and base stations. Therefore, reducing the propagation loss of high-frequency signals in the window material is also very useful.

[0146] When a glass plate is used as a window material, the glass plate may be a glass plate formed into a flat shape by, for example, a float method or a fusion method, or may be a bent glass plate formed by forming the flat glass plate into a curved shape by gravity forming, press forming, or the like, and may be arbitrarily deformed and used depending on the installation location.

[0147] The glass constituting the glass plate is not particularly limited and may be soda-lime glass, aluminosilicate glass, alkali-free glass, or the like, and may be appropriately selected depending on the intended use. Furthermore, the glass may be tempered glass having a compressive stress layer on the glass surface and a tensile stress layer inside the glass. As the tempered glass, either chemically tempered glass or air-cooled tempered glass (physically tempered glass) can be used. [Example]

[0148] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0149] [Example 1 to Example 4] Glass raw materials having the composition shown as Composition 1 in Table 1 were placed in a platinum crucible and melted in an electric furnace at 1650°C for 3 hours to obtain molten glass. During melting, a platinum stirrer was inserted into the platinum crucible and the mixture was stirred for 1 hour to homogenize the glass. The molten glass was poured onto a carbon plate and formed into a plate (melting and forming process). The plate-shaped molten glass was then placed in an electric furnace at a temperature of approximately (Tg+50)°C, and after maintaining the temperature for 1 hour, the temperature was lowered to room temperature at an average rate of 1°C / min to obtain a raw glass plate (cooling down process).

[0150] Next, the temperature was increased to 630°C at a rate of 10°C / min and maintained at 630°C for the time shown in "Maintaining time (min)" in Table 2. Thereafter, the temperature was decreased from 630°C to (Tg-300)°C in an electric furnace at the average temperature decrease rate shown in Table 2, and then the glass was allowed to cool naturally to room temperature to obtain a glass plate (heat treatment step). Examples 1 to 3 are working examples, and Example 4 is a comparative example.

[0151] The physical properties of the obtained glass plate were measured as follows. The results, along with the compositions, are shown in Tables 1 and 2. In the tables, blanks for composition indicate that no intentional addition was made, and blanks for physical properties indicate that no measurements were made.

[0152] [Glass transition temperature Tg (℃)] The glass transition temperature was measured using a thermal dilatometer (manufactured by MAC, model number TD5000SA) in accordance with JIS R 3103-3:2001.

[0153] [T2, T4 (℃)] The viscosity of the glass was measured, and T2 and T4 were calculated. Specifically, the viscosity of the glass was measured using a rotational high-temperature viscometer (Opto Enterprise Co., Ltd., RVM-550) in accordance with ASTM C965-96 (2002). The viscosity of the glass was corrected using MIST717a as a standard sample, and T2 and T4 were calculated.

[0154] [Devitrification temperature] The devitrification temperature was determined by placing crushed glass particles in a platinum dish, heat treating them for 17 hours in an electric furnace controlled at a constant temperature, and then observing the heat-treated sample with an optical microscope (Nikon, model ME600) to determine the average value of the maximum temperature at which crystals precipitate on the surface and inside of the glass and the minimum temperature at which crystals do not precipitate.

[0155] Young's Modulus The Young's modulus was measured using an ultrasonic pulse Young's modulus measuring device (Olympus Corporation, 38DL-PAUS) in accordance with JIS R 1602 (1995).

[0156] [Acid resistance] Acid resistance was measured by immersing a glass sample in an acid solution (6 wt% HNO3 + 5 wt% H2SO4, 45°C) for 170 seconds and measuring the amount of glass components dissolved per unit surface area (mg / cm 2 ) was evaluated.

[0157] [Alkali resistance] Alkali resistance was evaluated by immersing a glass sample in an alkaline aqueous solution (1.2 wt% NaOH, 60°C) for 30 minutes and measuring the amount of glass components dissolved per unit surface area (mg / cm 2 ) was evaluated.

[0158] [Average thermal expansion coefficient] The thermal expansion coefficient in the temperature range of 50 to 350°C was measured using a TMA (manufactured by MAC, model number TD5000SA) in accordance with JIS R 3102 (1995). From the results, the average value of the linear expansion coefficients in the range of 50 to 350°C was calculated as the average thermal expansion coefficient.

[0159] [Distortion point] The strain point was measured in accordance with JIS R 3103-2 (2001).

[0160] [density] The density was measured in accordance with JIS Z 8807 (2012).

[0161] [Dielectric tangent tanδ] The dielectric loss tangent tanδA at 10 GHz of the obtained glass plate was measured by the SPDR method using a 10 GHz resonator (manufactured by OWED, 10 GHz resonator) in accordance with IEC 61189-2-721(2015).

[0162] The glass plate was also heated to (Tg+50)°C and cooled to (Tg-150)°C at a rate of 100°C / min, and then the dielectric loss tangent tanδ100 at 10 GHz was similarly measured. In the table, Δtanδ indicates the value of (tanδ100-tanδA).

[0163] [Relative permittivity εr] The relative permittivity εrA of the obtained glass plate at 10 GHz was measured by the SPDR method using a 10 GHz resonator (manufactured by OWED, 10 GHz resonator) in accordance with IEC 61189-2-721(2015).

[0164] The glass plate was also heated to (Tg+50)°C and cooled to (Tg-150)°C at a rate of 100°C / min, and then the relative dielectric constant εr100 at 10 GHz was similarly measured.

[0165] [Table 1]

[0166] [Table 2]

[0167] [Examples 5 to 8] Glass plates were obtained in the same manner as in Example 1, except that glass raw materials having the composition shown as Composition 2 in Table 1 were used, and that in the subsequent heat treatment step, the temperature was increased to 597°C at a rate of 10°C / min, held at 597°C for the time shown in "Holding time (min)" in Table 3, and then cooled in an electric furnace to (Tg-300)°C at an average cooling rate shown in Table 3. Examples 5 to 7 are working examples, and Example 8 is a comparative example.

[0168] The physical properties of the obtained glass plate were measured under the same conditions as in Example 1. The results are shown in Tables 1 and 3 together with the composition.

[0169] [Table 3]

[0170] [Examples 9 to 12] Glass plates were obtained in the same manner as in Example 1, except that glass raw materials having the composition shown as Composition 3 in Table 1 were used, and that in the subsequent heat treatment step, the temperature was increased to 653°C at a rate of 10°C / min, held at 653°C for the time shown in "Holding time (min)" in Table 4, and then cooled in an electric furnace to (Tg-300)°C at an average cooling rate shown in Table 4. Examples 9 to 11 are working examples, and Example 12 is a comparative example.

[0171] The physical properties of the obtained glass plate were measured under the same conditions as in Example 1. The results are shown in Tables 1 and 4 together with the composition.

[0172] [Table 4]

[0173] [Examples 13 to 16] Glass plates were obtained in the same manner as in Example 1, except that glass raw materials having the composition shown as Composition 4 in Table 1 were used, and that in the subsequent heat treatment step, the temperature was increased to 675°C at a rate of 10°C / min, held at 675°C for the time shown in the "Holding time (min)" column in Table 5, and then cooled in an electric furnace to (Tg-300)°C at the average cooling rate shown in Table 5. Examples 13 to 15 are working examples, and Example 16 is a comparative example.

[0174] The physical properties of the obtained glass plate were measured under the same conditions as in Example 1. The results are shown in Tables 1 and 5 together with the composition.

[0175] [Table 5]

[0176] [Examples 17 to 20] Glass plates were obtained in the same manner as in Example 1, except that glass raw materials having the composition shown as Composition 5 in Table 1 were used, and that in the subsequent heat treatment step, the temperature was increased to 760°C at a rate of 10°C / min, held at 760°C for the time shown in the "Holding time (min)" column in Table 6, and then cooled in an electric furnace to (Tg-300)°C at the average cooling rate shown in Table 6. Examples 17 to 19 are working examples, and Example 20 is a comparative example.

[0177] The physical properties of the obtained glass plate were measured under the same conditions as in Example 1. The results are shown in Tables 1 and 6 together with the composition.

[0178] [Table 6]

[0179] [Examples 21 to 24] Glass plates were obtained in the same manner as in Example 1, except that glass raw materials having the composition shown as Composition 6 in Table 1 were used, and that in the subsequent heat treatment step, the temperature was increased to 760°C at a rate of 10°C / min, held at 760°C for the time shown in the "Holding time (min)" column in Table 7, and then cooled in an electric furnace to (Tg-300)°C at the average cooling rate shown in Table 7. Examples 21 to 23 are working examples, and Example 24 is a comparative example.

[0180] The physical properties of the obtained glass plate were measured under the same conditions as in Example 1. The results are shown in Tables 1 and 7 together with the composition.

[0181] [Table 7]

[0182] [Examples 25 to 28] Glass plates were obtained in the same manner as in Example 1, except that glass raw materials having the composition shown as Composition 7 in Table 1 were used, and that in the subsequent heat treatment step, the temperature was increased to 700°C at a rate of 10°C / min, held at 700°C for the time shown in the "Holding time (min)" column in Table 8, and then cooled in an electric furnace to (Tg-300)°C at the average cooling rate shown in Table 8. Examples 25 to 27 are working examples, and Example 28 is a comparative example.

[0183] The physical properties of the obtained glass plate were measured under the same conditions as in Example 1. The results are shown in Tables 1 and 8 together with the composition.

[0184] [Table 8]

[0185] [Examples 29 to 31] Glass raw materials having the composition shown as composition 4 in Table 1 were used and formed into a plate shape using a glass melting furnace and forming equipment (melting and forming process). Thereafter, the plate-shaped molten glass heated to 700°C was cooled to room temperature at an average cooling rate of 50°C / min using slow cooling equipment, to obtain a raw glass plate measuring 37cm x 47cm and 1.1mm thick (cooling step).

[0186] Next, the temperature was increased at 10°C / min to Tmax°C in Table 9, and the glass sheets were held at Tmax°C for the time shown in the "Holding time (min)" column in Table 9, and then the temperature was decreased in the electric furnace to (Tg-300)°C at the average temperature decreasing rate shown in Table 9. Examples 29 to 31 are working examples.

[0187] The temperature of the electric furnace was adjusted so that the ratio of VC / VE was 1.1 or less, where VC (°C / min) is the average cooling rate at the center of the glass plate and VE (°C / min) is the average cooling rate at the edge of the glass plate. Here, the edge of the glass plate refers to a position 10 cm from the edge of the glass plate.

[0188] The dielectric constant and dielectric loss tangent of the obtained glass plate were measured under the same conditions as in Example 1, except that measurements were taken at four locations, approximately at the center and near the corners of the plate, and the maximum and minimum values ​​were recorded. The results are shown in Table 9.

[0189] Table 9 also shows the minimum value of Δtanδ and the maximum value of εr100 / εrA. Table 9 also shows the difference in tanδA at the two locations with the largest difference in tanδA, and the difference in εrA at the two locations with the largest difference in εrA, out of four locations near the center and corners of the plate.

[0190] [Table 9]

[0191] [Example 32 to Example 34] Glass raw materials having the composition shown as composition 6 in Table 1 were used and formed into a plate shape using a glass melting furnace and forming equipment (melting and forming process). Thereafter, the plate-shaped molten glass at 800°C was cooled to room temperature at an average cooling rate of 800°C / min using slow cooling equipment, to obtain a raw glass plate of 37cm x 47cm and 1.1mm thick (cooling step).

[0192] Next, the temperature was increased at 10°C / min to Tmax°C in Table 10, and the glass plates were held at Tmax°C for the time shown in the "Holding time (min)" column in Table 10, and then the temperature was decreased in the electric furnace to (Tg-300)°C at the average temperature decreasing rate shown in Table 10, in the same manner as in Example 1, except that the glass plates were obtained. Examples 32 to 34 are working examples.

[0193] The temperature of the electric furnace was adjusted so that the ratio of VC / VE was 1.1 or less, where VC (°C / min) is the average cooling rate at the center of the glass plate and VE (°C / min) is the average cooling rate at the edge of the glass plate. Here, the edge of the glass plate refers to a position 10 cm from the edge of the glass plate.

[0194] The relative permittivity and dielectric loss tangent of the obtained glass plate were measured under the same conditions as in Example 1, except that measurements were taken at approximately the center of the plate and four locations near the corners, and the maximum and minimum values ​​were recorded. The results are shown in Table 10.

[0195] Table 9 shows the minimum value of Δtanδ and the maximum value of εr100 / εrA. Table 10 also shows the difference in tanδA at the two locations with the largest difference in tanδA, and the difference in εrA at the two locations with the largest difference in εrA, out of four locations near the center and corners of the plate.

[0196] [Table 10]

[0197] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on April 12, 2019 (Patent Application No. 2019-76423), June 28, 2019 (Patent Application No. 2019-120828), and November 27, 2019 (Patent Application No. 2019-214690), all of which are incorporated by reference in their entireties. All references cited herein are incorporated by reference in their entireties.

Claims

1. A glass plate having a dielectric loss tangent of tanδA at 10 GHz and a glass transition temperature of Tg°C, The glass plate satisfies (tan δ100-tan δA)≧0.0004, where tan δ100 is the dielectric loss tangent at 10 GHz when the glass plate is heated to (Tg+50)°C and then cooled to (Tg-150)°C at a rate of 100°C / min.

2. The relative permittivity at 10 GHz is εrA, The glass plate according to claim 1, wherein the glass plate is heated to (Tg+50)°C and then cooled to (Tg-150)°C at a rate of 100°C / min, and the relative dielectric constant at 10 GHz is defined as εr100, and the relationship 0.95≦(εr100 / εrA)≦1.05 is satisfied.

3. The area of ​​the main surface is 350 cm ２ The glass plate according to claim 1 or 2.

4. The glass plate according to any one of claims 1 to 3, which has a dielectric loss tangent at 10 GHz of 0.009 or less.

5. The glass plate according to any one of claims 1 to 4, which has a relative dielectric constant at 10 GHz of 6.8 or less.

6. The glass plate according to any one of claims 1 to 5, wherein a difference in dielectric loss tangent at 10 GHz between any two points that are 40 mm or more apart is 0.0005 or less.

7. The glass plate according to any one of claims 1 to 6, wherein a difference in relative dielectric constant at 10 GHz between any two points that are 40 mm or more apart is 0.05 or less.

8. In terms of mole percentage based on oxide, SiO ２ The glass plate according to any one of claims 1 to 7, containing 30 to 85% of

9. In mole percentage based on oxides, Yes ２ 57~70% Al ２ O ３ 5~15% B ２ O ３ 15~24% Al ２ O ３ +B ２ O ３ 20~40% Al ２ O / (Al ２ O ３ +B ２ O ３ ) 0.1~0.45 MgO 0-10% CaO 0-10% SrO 0-10% BaO 0-10% Li ２ O 0~5% Na ２ O0~5% K ２ O 0-5%, and R ２ O (R = alkali metal) 0-5% The glass plate according to any one of claims 1 to 8, comprising:

10. In mole percentage based on oxides, Yes ２ 55~80% Al ２ O ３ 0~15% SiO ２ +Al ２ Oh ３ 55~90% B ２ O ３ 0~15% MgO 0-20% CaO 0-20% SrO 0-15% BaO 0-15% MgO+CaO 0-30% MgO+CaO+SrO+BaO 0-30% Li ２ O 0~20% Na ２ O0~20% K ２ O 0-20%, and R ２ O (R = alkali metal) 0-20% The glass plate according to any one of claims 1 to 8, comprising:

11. The glass plate according to any one of claims 1 to 9, which is used as a substrate for a high-frequency device that handles high-frequency signals of 3.0 GHz or more.

12. The glass plate according to any one of claims 1 to 8 and 10, which is used as a window material.

13. A method for producing a glass plate according to any one of claims 1 to 12, a melting and forming process in which the molten glass obtained by melting the glass raw materials is formed into a sheet; a temperature-reducing step of reducing the temperature of the molten glass formed into a plate shape to a temperature of (Tg-300)°C or lower relative to the glass transition temperature Tg (°C) to obtain a raw glass plate; a heat treatment step in which the obtained raw glass plate is heated from a temperature of not more than (Tg-300)°C to a temperature in the range of (Tg-100)°C to (Tg+50)°C without exceeding (Tg+50)°C, and then cooled again to not more than (Tg-300)°C; The heat treatment step is carried out once or twice or more times, One heat treatment step is a period from when the temperature of the glass plate exceeds (Tg-300)°C, passes through a maximum temperature Temax°C in the range of (Tg-100)°C to (Tg+50)°C, and then drops to (Tg-300)°C or lower again. the total time during which the temperature of the glass plate is in the range of (Tg-100)°C to (Tg+50)°C throughout the heat treatment process is equal to or longer than K (minutes) expressed by the following formula (1), where Tmax°C is the maximum temperature of the glass plate throughout the heat treatment process: In each of the heat treatment steps, when the time from the last time at which the temperature starts to decrease from the maximum temperature Temax ° C. in each of the heat treatment steps to the time at which the temperature finally passes (Tg-110) ° C. is defined as t1 (minutes), the following formula (2) is satisfied. K=[{(Tg+50)-Tmax} / 10]+15 Formula (1) {Temax-(Tg-110)} / t1≦10 Formula (2)

14. 14. The method for manufacturing a glass plate according to claim 13, wherein, in each heat treatment step, the temperature of the raw glass plate is lowered from the maximum temperature Temax ° C. and, after initially falling below (Tg-110) ° C., does not exceed (Tg-110) ° C. again.

15. In each heat treatment step, any two times between the last time when the temperature starts to decrease from the maximum temperature Temax ° C. in each heat treatment step and the last time when the temperature passes through (Tg-110) ° C. are defined as t2 (minutes) and t3 (minutes), and t2<t3: The time difference between t2 and t3 is 1 minute or more, The method for manufacturing a glass plate according to claim 13 or 14, wherein the following formula (3) is satisfied, where Te2 is the temperature of the glass plate at t2 and Te3 is the temperature of the glass plate at t3: (Te2-Te3) / (t3-t2)≦10 Formula (3)

16. The method for producing a glass plate according to any one of claims 13 to 15, wherein an average temperature decreasing rate from (Tg + 50) ° C. to (Tg - 100) ° C. in the temperature decreasing step is more than 10 ° C. / min.

17. The method for manufacturing a glass plate according to any one of claims 13 to 16, wherein an average temperature decreasing rate in the temperature decreasing step is 10 to 1000°C / min.

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