Glass sheet and method of manufacturing the same

Abstract

Provided is a novel glass sheet that can be used as a substrate or window material for high-frequency devices and has a low propagation loss or transmission loss in a high-frequency band. The glass sheet is a glass sheet having a dielectric loss tangent tan delta A at 10 GHz and a glass transition temperature Tg (°C), and satisfies (tan delta 100 - tan delta A) >= 0.0004 when the dielectric loss tangent is set to tan delta 100 upon heating the glass sheet to (Tg + 50) °C and then cooling it to (Tg - 150) °C at a rate of 100 °C / min.

Description

[0001] This application is a divisional application of Chinese patent application number 202080028313.1 (the original application was entitled "Glass Plate and Method of Manufacturing Thereof", and the original application was filed on April 7, 2020). Technical Field

[0002] This invention relates to glass plates and methods for manufacturing them. Background Technology

[0003] Devices that utilize radio waves, such as vehicles like automobiles, radar used indoors in buildings, and mobile phones (hereinafter referred to as "radio wave utilization devices"), are examples of such devices. In particular, there is a recent surge in the development of radio wave utilization devices that utilize high-frequency bands (microwaves to millimeter waves), and more specifically, gigahertz bands, such as the 3 to 300 GHz region.

[0004] The circuit boards used in such high-frequency radio wave utilization devices (hereinafter referred to as "high-frequency devices") are generally insulating substrates such as resin substrates, ceramic substrates, and glass substrates. In order to ensure the quality, strength, and other characteristics of high-frequency signals, the insulating substrates used in high-frequency devices are required to reduce transmission losses based on dielectric loss, conductor loss, etc.

[0005] On the other hand, glass panels used as window materials in automobiles and other vehicles, as well as buildings, require high visible light transmittance, high ultraviolet and solar shading performance, and good visual appeal. Patent Document 1 discloses an ultraviolet and infrared absorbing glass made of a sodium-calcium-silicon glass with a specific composition.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2002-348143 Summary of the Invention

[0009] However, given the use of millimeter-wave radar in vehicles such as cars and electronic equipment in buildings, the glass panels used as window materials for these applications are required to have reduced propagation and transmission losses, just like the insulating substrates for high-frequency devices.

[0010] Therefore, the object of the present invention is to provide a new glass plate and its manufacturing method that can be used as a substrate and window material for high-frequency devices and has low propagation loss and transmission loss in the high-frequency band.

[0011] The present invention relates to the following solutions.

[0012] 1. A glass plate having a dielectric loss tangent of tanδA at 10 GHz and a glass transition temperature of Tg℃.

[0013] When the dielectric loss tangent of the glass plate is heated to (Tg+50)℃ and then cooled to (Tg-150)℃ at a rate of 100℃ / min, and is set to tanδ100, (tanδ100-tanδA)≥0.0004.

[0014] 2. The glass plate according to 1 above, wherein the relative permittivity at 10 GHz is εrA.

[0015] When the relative permittivity of the glass plate at 10 GHz is set to εr100, which is the result of heating the glass plate to (Tg+50)℃ and then cooling it to (Tg-150)℃ at a rate of 100℃ / min, the following condition is satisfied: 0.95≤(εr100 / εrA)≤1.05.

[0016] 3. The glass plate according to 1 or 2 above, wherein the area of ​​the main surface is 350 cm². 2 above.

[0017] 4. The glass plate according to any one of 1 to 3 above, wherein the dielectric loss tangent at 10 GHz is 0.009 or less.

[0018] 5. The glass plate according to any one of 1 to 4 above, wherein the relative permittivity at 10 GHz is 6.8 or less.

[0019] 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 at least 40 mm apart is 0.0005 or less.

[0020] 7. The glass plate according to any one of 1 to 6 above, wherein the difference in the relative permittivity at 10 GHz between any two points spaced at least 40 mm apart is 0.05 or less.

[0021] 8. The glass plate according to any one of 1 to 7 above, wherein it contains 30 to 85% SiO2, expressed as a molar percentage based on oxides.

[0022] 9. The glass plate according to any one of claims 1 to 8 above, wherein,

[0023] Expressed as a molar percentage based on oxides, it contains:

[0024] SiO2 57-70%,

[0025] Al2O3 5-15%,

[0026] B2O3 15-24%,

[0027] Al2O3 + B2O3 20-40%,

[0028] Al2O / (Al2O3+B2O3)0.1~0.45,

[0029] MgO 0-10%,

[0030] CaO 0-10%,

[0031] SrO 0-10%,

[0032] BaO 0-10%,

[0033] Li2O 0-5%,

[0034] Na2O 0-5%,

[0035] K2O 0-5%, and

[0036] R₂O (R = alkali metal) 0–5%.

[0037] 10. The glass plate according to any one of claims 1 to 8 above, wherein,

[0038] Expressed as a molar percentage based on oxides, it contains:

[0039] SiO2 55-80%,

[0040] Al2O3 0-15%,

[0041] SiO2 + Al2O3 55–90%,

[0042] B2O3 0-15%,

[0043] MgO 0-20%,

[0044] CaO 0-20%,

[0045] SrO 0-15%,

[0046] BaO 0-15%,

[0047] MgO + CaO 0-30%,

[0048] MgO + CaO + SrO + BaO 0–30%,

[0049] Li2O 0-20%,

[0050] Na2O 0-20%,

[0051] K2O 0-20%, and

[0052] R₂O (R = alkali metal) 0–20%.

[0053] 11. The glass plate according to any one of 1 to 9 above is used as a substrate for a high-frequency device that processes high-frequency signals above 3.0 GHz.

[0054] 12. The glass plate according to any one of 1 to 8 and 10 above is used as a window material.

[0055] 13. A method for manufacturing a glass plate, comprising the following steps in sequence:

[0056] The melting and forming process involves melting the glass raw material and then forming the molten glass into a plate shape.

[0057] The cooling process involves cooling the molten glass, which has been formed into a plate shape, to a temperature below (Tg-300)°C relative to the glass transition temperature Tg (°C) to obtain a glass preform.

[0058] The heat treatment process involves heating the obtained glass blank from a temperature below (Tg-300)℃ to a range of (Tg-100)℃ to (Tg+50)℃ without exceeding (Tg+50)℃, and then cooling it again to below (Tg-300)℃.

[0059] Performing the above heat treatment process once or twice or more,

[0060] One of the above heat treatment processes involves the glass blank being heated to a temperature exceeding (Tg-300)℃, then subjected to a maximum temperature Temax℃ within the range of (Tg-100)℃ to (Tg+50)℃, until the temperature falls below (Tg-300)℃ again.

[0061] In the entire heat treatment process described above, the total time during which the temperature of the glass blank is in the range of (Tg-100)℃~(Tg+50)℃ is greater than or equal to K (minutes) of the highest temperature Tmax℃ of the glass blank in the entire heat treatment process described above, expressed by the following formula (1).

[0062] In each of the above heat treatment processes, if the time from the last moment of cooling down from the highest temperature Temax℃ to the moment when (Tg-110)℃ is set as t1 (minutes), the following equation (2) is satisfied.

[0063] K = [{(Tg+50)-Tmax} / 10]+15 Equation (1)

[0064] {Temax-(Tg-110)} / t1≤10 Equation (2)

[0065] 14. The method for manufacturing a glass plate according to 13 above, wherein, in each of the above heat treatment processes, after the temperature of the glass blank plate drops from the highest temperature Temax℃ and first falls below (Tg-110)℃, it will not exceed (Tg-110)℃ again.

[0066] 15. The method for manufacturing a glass plate according to 13 or 14 above, wherein, in each of the above heat treatment steps, any two moments from the last moment of cooling down from the highest temperature Temax℃ until the moment when (Tg-110)℃ is finally passed are set as t2 (minutes) and t3 (minutes), and t2<t3.

[0067] The difference between time t2 and time t3 mentioned above is more than 1 minute.

[0068] When the temperature of the glass blank at t2 is set to Te2 and the temperature of the glass blank at t3 is set to Te3, the following equation (3) is satisfied.

[0069] (Te2-Te3) / (t3-t2)≤10 Formula (3)

[0070] 16. The method for manufacturing a glass plate according to any one of 13 to 15 above, wherein the average cooling rate from (Tg+50)℃ to (Tg-100)℃ in the cooling process exceeds 10℃ / minute.

[0071] 17. The method for manufacturing a glass plate according to any one of 13 to 16 above, wherein the average cooling rate in the cooling process is 10 to 1000°C / minute.

[0072] The glass plate according to the present invention exhibits low absorption of high-frequency electromagnetic waves, enabling high transmittance. By using such a glass plate as a circuit board, practical high-frequency devices such as electronic devices can be provided with reduced propagation and transmission losses. Furthermore, by using this glass plate as window material in vehicles such as automobiles and buildings, electromagnetic waves can be propagated without significant attenuation when millimeter-wave radar is installed inside vehicles or when electronic devices are used in buildings. Detailed Implementation

[0073] The present invention will now be described in detail, but it is not limited to the embodiments described below and can be implemented in any way without departing from the spirit of the invention. Furthermore, the "~" indicating a numerical range is used to mean that the values ​​before and after it are both lower and upper limits. Also, unless otherwise specified, the "%" indicating the composition of the glass plate is a value expressed as a molar percentage based on oxides.

[0074] <Glass Plate>

[0075] In this embodiment, the dielectric loss tangent of the glass plate at 10 GHz is tanδA, and the glass transition temperature is Tg℃. When the dielectric loss tangent of the glass plate is set to tanδ100 when it is heated to (Tg+50)℃ and then cooled to (Tg-150)℃ at 100℃ / min, the relationship (tanδ100-tanδA)≥0.0004 is satisfied.

[0076] The dielectric loss tangent of a glass plate (hereinafter sometimes simply referred to as "tanδ") is a value expressed using the complex permittivity as ε” / ε', where ε' is the relative permittivity and ε” is the dielectric loss. The smaller the value of tanδ, the less electromagnetic wave absorption occurs in its frequency band, enabling high transmittance.

[0077] It should be noted that in this specification, the dielectric loss tangent and relative permittivity are values ​​measured at a frequency of 10 GHz according to the method specified in IEC 61189-2-721 (2015).

[0078] Generally, the value of tanδ can be adjusted by changing the glass composition. However, this invention has discovered a method to adjust the value of tanδ without changing the glass composition. Therefore, even with the same composition, glass with a smaller tanδ value can be obtained than before.

[0079] In glass manufacturing, varying the cooling rate yields glass with different densities. Specifically, a rapid cooling rate results in a low-density (coarse) glass state, while a slow cooling rate results in a high-density (dense) glass state. It is known that the density of this glass state is related to the value of tanδ in the high-frequency band.

[0080] That is, if the density of the glass state is high and dense, the transmittance of electromagnetic waves in the high-frequency band can be increased (reducing absorption), and the value of tanδ in the high-frequency band becomes smaller. It should be noted that the high-frequency band in this specification is generally above 3.0 GHz, especially above 3.5 GHz, and the actual verification was carried out at 10 GHz.

[0081] The glass plate of this embodiment has a smaller tanδA value at high frequencies than conventional glass plates of the same composition. This can be determined by the value of (tanδ100 - tanδA) mentioned above. That is, if a glass plate with a dielectric loss tangent of tanδA at 10 GHz is heated to (Tg + 50) °C and then cooled to (Tg - 150) °C at a rate of 100 °C / min, the value of tanδ100 is greater than the value of tanδA [(tanδ100 - tanδA) > 0], then the glass plate is a glass plate obtained at a cooling rate of less than 100 °C / min, has a high density, and exhibits high transmittance.

[0082] Furthermore, by satisfying the relationship that (tanδ100-tanδA) is greater than or equal to 0.0004 [(tanδ100-tanδA)≥0.0004], it can be said that compared with the glass plates of the same composition in the past, the value of tanδA is small enough to show high transmittance to electromagnetic waves in the high-frequency band.

[0083] Thus, the tanδA of the glass plate only needs to satisfy the relationship (tanδ100-tanδA)≥0.0004, but in order to show further high transmittance, it is preferable that (tanδ100-tanδA)≥0.0005, and even more preferably (tanδ100-tanδA)≥0.0006.

[0084] There is no specific upper limit for (tanδ100-tanδA), but in order to shorten the heat treatment time and improve productivity, it can be (tanδ100-tanδA)≤0.001, (tanδ100-tanδA)≤0.0008, (tanδ100-tanδA)≤0.0007, or (tanδ100-tanδA)≤0.0006.

[0085] The difference in the dielectric loss tangent tanδ at 10 GHz between any two points 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. If the difference in the 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 to be a homogeneous glass plate without uneven cooling rates, which is therefore preferred. Here, "any two points 40 mm or more apart" refers to any two points on the same plane that are 40 mm or more apart.

[0086] The lower limit of the difference of dielectric loss tangent tanδ at 10 GHz between any two points more than 40 mm apart on the glass plate is not particularly limited and can be greater than 0.0001.

[0087] When the relative permittivity at 10 GHz is set to εr100 when the glass plate is heated to (Tg+50)℃ and then cooled to (Tg-150)℃ at a rate of 100℃ / min, the relative permittivity εrA of the glass plate 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, and even more preferably 0.99 or more. Furthermore, it is more preferably 1.03 or less, even more preferably 1.02 or less, and particularly preferably 1.01 or less.

[0088] Unlike the value of tanδA, the relative permittivity εr of the glass plate can be obtained with approximately the same value even if the cooling rate during manufacturing is changed. Therefore, it is possible to reduce device losses without significantly altering the design of high-frequency devices.

[0089] The difference in relative permittivity εrA at 10 GHz between any two points spaced at least 40 mm apart on the glass plate is preferably 0.05 or less, more preferably 0.04 or less, and even more preferably 0.03 or less. If the difference in relative permittivity εrA is 0.05 or less, the in-plane distribution of the relative permittivity is small, resulting in a homogeneous glass plate without uneven cooling rates, which is therefore preferable. The lower limit of the difference in relative permittivity εrA at 10 GHz between any two points spaced at least 40 mm apart on the glass plate is not particularly limited and can be 0.01 or more.

[0090] Glass plates with such properties are preferred for use as substrates and window materials for high-frequency devices, and are even more preferred for high-frequency devices that process high-frequency signals above 3.0 GHz, especially above 3.5 GHz.

[0091] The glass plate preferably contains 30-85% SiO2, expressed as a molar percentage based on oxides. Alkali-free glass is more preferred as a substrate for high-frequency devices, and soda-lime glass is more preferred as a window material.

[0092] The specific preferred glass compositions for each application are as follows.

[0093] When a glass plate is used as a substrate for a high-frequency device, the following composition is more preferably expressed as a molar percentage based on oxides.

[0094] SiO2 57-70%

[0095] Al2O3 5-15%

[0096] B2O3 15-24%

[0097] Al2O3 + B2O3 20-40%

[0098] Al₂O / (Al₂O₃+B₂O₃) = 0.1–0.45

[0099] MgO 0-10%

[0100] CaO 0-10%

[0101] SrO 0-10%

[0102] BaO 0-10%

[0103] Li2O 0-5%

[0104] Na2O 0-5%

[0105] K2O 0-5%, and

[0106] R2O (R = alkali metal element) 0-5%

[0107] The following is an explanation of each component.

[0108] SiO2 is a network-forming material. If its content is 57% or more, it provides good glass-forming ability and weather resistance, and also suppresses devitrification, making it preferred. More preferably, the SiO2 content is 58% or more, further preferably 60% or more, and even more preferably 61% or more. Furthermore, if the SiO2 content is 70% or less, it provides good glass solubility, making it preferred. More preferably, it is 68% or less, further preferably 66% or less, even more preferably 65% ​​or less, particularly preferably 64% or less, and most preferably 63% or less.

[0109] Al2O3 is a component that improves weather resistance, increases Young's modulus, suppresses phase separation in glass, and reduces the coefficient of thermal expansion. A content of 5% or more of Al2O3 is preferred as it provides sufficient benefits. More preferably, the content is 6% or more, further preferably 7% or more, and even more preferably 8% or more. Furthermore, a content of 15% or less of Al2O3 results in good glass solubility and is therefore preferred. More preferably, the content is 14% or less, further preferably 13% or less, and even more preferably 12% or less.

[0110] B2O3 is a component that improves solubility, and its content is preferably 15% or more. Furthermore, this component is also capable of reducing the dielectric loss tangent in the high-frequency region; therefore, its content is more preferably 16% or more, further 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 content of B2O3 is preferably 24% or less, more preferably 23% or less, and even more preferably 22% or less.

[0111] From the viewpoint of glass solubility, the total content of Al2O3 and B2O3 (Al2O3 + B2O3) is more preferably 20% or more, particularly preferably 25% or more. Furthermore, from the viewpoint of maintaining glass solubility while improving the low dielectric loss of the glass sheet, the total content is preferably 40% or less, more preferably 37% or less, further preferably 35% or less, and particularly preferably 33% or less.

[0112] MgO is a component that increases Young's modulus without increasing specific gravity, thereby increasing specific elastic modulus, reducing flexural problems, increasing fracture toughness, and thus improving glass strength. Furthermore, MgO also improves solubility and prevents the coefficient of thermal expansion from becoming too low. MgO may be absent, but when present, it is preferably 0.1% or more, more preferably 0.2% or more, further preferably 1% or more, and even more preferably 2% or more. From the viewpoint of suppressing the rise in devitrification temperature, the MgO content is preferably 10% or less, more preferably 9% or less, further preferably 8% or less, even more preferably 7% or less, even more preferably 6% or less, particularly preferably 5% or less, especially preferably 4% or less, and most preferably 3% or less.

[0113] CaO is a component that, among alkaline earth metals, has the characteristic of increasing the specific elastic modulus second only to MgO without excessively lowering the strain point, and also improves solubility similarly to MgO. Furthermore, this component also has the characteristic of not easily increasing the devitrification temperature compared to MgO. CaO may be absent, but when CaO is present, it is preferably 0.1% or more, more preferably 0.2% or more, further preferably 0.5% or more, even more preferably 1% or more, and particularly preferably 2% or more. In addition, from the viewpoint of preventing the average coefficient of thermal expansion from becoming too high and suppressing the rise of devitrification temperature to prevent devitrification during glass manufacturing, its content is preferably 10% or less, more preferably 8% or less, further preferably 7% or less, even more preferably 6% or less, even more preferably 5% or less, particularly preferably 4% or less, and especially preferably 3% or less.

[0114] SrO is a component that does not raise the devitrification temperature of glass and improves its solubility. SrO may be absent, but when present, it is preferably 0.1% or more, more preferably 0.2% or more, further preferably 0.5% or more, even more preferably 1% or more, and particularly preferably 2% or more. Furthermore, from the viewpoint of not causing excessive specific gravity and suppressing excessively high average coefficient of thermal expansion, its content is preferably 10% or less, more preferably 9% or less, further preferably 8% or less, even more preferably 7% or less, even more 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.

[0115] BaO is a component that does not raise the devitrification temperature of glass and improves its solubility. BaO may be absent, but when present, it is preferably 0.1% or more, more preferably 0.2% or more, further preferably 1% or more, and particularly preferably 2% or more. Furthermore, from the perspective of increasing specific gravity, decreasing Young's modulus, increasing relative permittivity, and causing excessively large average coefficient of thermal expansion, its content is preferably 10% or less, more preferably 8% or less, further preferably 5% or less, and even more preferably 3% or less.

[0116] ZnO is a component that improves chemical resistance; however, there are concerns about its tendency to separate into phases and its increased 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, and even more preferably 0.01% or less, and particularly preferably substantially non-existent. "Substantially non-existent" means, for example, less than 0.01%.

[0117] From the viewpoint of improving acid resistance and suppressing phase separation to achieve excellent glass homogeneity, the molar ratio expressed as {Al2O3 / (Al2O3+B2O3)} is preferably 0.1 or higher. Furthermore, from the perspective of improving Young's modulus, this molar ratio is more preferably 0.3 or higher, even more preferably 0.33 or higher, even more preferably 0.35 or higher, and particularly preferably 0.38 or higher. Additionally, from the perspective of reducing dielectric loss in high-frequency regions such as 10 GHz and above, preferably above 30 GHz, the molar ratio is preferably 0.45 or lower, more preferably 0.4 or lower, even more preferably 0.35 or lower, and even more preferably 0.3 or lower.

[0118] When the molar percentages of Al2O3, MgO, CaO, SrO, and BaO, expressed as oxide-based values, are respectively set as [Al2O3], [MgO], [CaO], [SrO], and [BaO], from the perspective of acid resistance, the value expressed by {[Al2O3]-([MgO]+[CaO]+[SrO]+[BaO])} is preferably greater than -3, more preferably -2 or more, even more preferably -1 or more, and particularly preferably -0.5 or more. Furthermore, from the perspective of suppressing glass devitrification, 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.

[0119] From the perspective of reducing surface devitrification temperature and improving glass production efficiency, the molar ratio of the content expressed as {(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. Furthermore, since the raw material prices of SrO and BaO are high, from the viewpoint of reducing raw material prices, the molar ratio is preferably 0.85 or less, even more preferably 0.8 or less. Here, RO represents the total amount of MgO, CaO, SrO, and BaO.

[0120] R2O represents the total amount of alkali metal oxides. Examples of alkali metal oxides include Li2O, Na2O, K2O, Rb2O, and Cs2O. Since the presence of Rb2O and Cs2O among alkali metal oxides in glass is rare, R2O usually refers to the total content of Li2O, Na2O, and K2O (Li2O + Na2O + K2O).

[0121] The glass may not contain alkali metal oxides, but by including alkali metal oxides, practical glass melt properties and glass sheet productivity can be obtained without excessive raw material refining, and the coefficient of thermal expansion of the glass sheet can be adjusted. Therefore, when alkali metal oxides are included, the total (R₂O) content is preferably 0.001% or more, more preferably 0.002% or more, further preferably 0.003% or more, and particularly preferably 0.005% or more. In addition, from the perspective of improving the low dielectric loss of the glass sheet, the total content is preferably 5% or less, more preferably 3% or less, further preferably 1% or less, even more preferably 0.2% or less, even more preferably 0.1% or less, and particularly preferably 0.05% or less.

[0122] As an alkali metal oxide, the content of Li₂O is preferably 0-5%, more preferably 0.1% or more, even more preferably 0.2% or more, and further preferably 4% or less, even more preferably 3% or less. The content of Na₂O is preferably 0-5%, more preferably 0.1% or more, even more preferably 0.2% or more, and further preferably 4% or less, even more preferably 3% or less. The content of K₂O is preferably 0-5%, more preferably 0.1% or more, even more preferably 0.2% or more, and further preferably 4% or less, even more preferably 3% or less.

[0123] In addition to the above, Fe may be included to reduce the resistivity in the melting temperature region, for example, the resistivity at 1500°C. When Fe is included, it is preferably 0.01% or more, more preferably 0.05% or more, calculated as Fe2O3. However, if the Fe content is too high, there is a concern that the transmittance in the visible region will decrease. Therefore, 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.

[0124] From the perspective of reducing the resistance value in the temperature range where glass raw materials are melted, such as around 1500°C, making it suitable for melting glass by electric heating, the β-OH value, which is an indicator of the moisture content in the glass, is preferably 0.05 mm. -1 The above, more preferably 0.1mm -1 The above is further preferred to be 0.2mm. -1 The above, especially preferred, is 0.3mm. -1 That's all. Furthermore, from the perspective of reducing bubble defects in the glass, a β-OH value of 1.0 mm is preferred. -1 The following is more preferably 0.8mm -1 Hereinafter, 0.6mm is further preferred. -1 The following is particularly preferred: 0.5mm -1 the following.

[0125] It should be noted that the β-OH value in this specification is obtained by measuring the absorbance of a glass sample for light with wavelengths of 2.75–2.95 μm and setting the maximum absorbance β as the denominator. max The value is obtained by dividing by the thickness (mm) of the sample.

[0126] To improve the clarity of the glass plate, it may contain at least one component selected from SnO2, Cl, and SO3. When the total content of SiO2, Al2O3, RO, and R2O (SiO2+Al2O3+RO+R2O) is set to 100% as a mass percentage based on oxides, their total content (SnO2+Cl+SO3) can be 0.01 to 1.0% by mass. The total content is preferably 0.80% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less. Furthermore, the total content is preferably 0.02% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.10% by mass or more.

[0127] To improve the acid resistance of the glass, it may also contain at least one component selected from Sc2O3, TiO2, ZnO2, Ga2O3, GeO2, Y2O3, ZrO2, Nb2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3, and Lu2O3 (hereinafter referred to as "trace components"). However, if the content of trace components is too high, the homogeneity of the glass will decrease and phase separation will easily occur. Therefore, the total content of trace components, expressed as a molar percentage based on oxides, shall be 1.0% or less. It may contain only one of the above-mentioned trace components, or it may contain two or more.

[0128] For purposes such as improving solubility, lowering strain point, lowering glass transition temperature, and lowering slow cooling point, it may also contain F. However, in order to prevent an increase in bubble defects in the glass, when the total content of SiO2, Al2O3, RO, and R2O (SiO2+Al2O3+RO+R2O) is set to 100% by mass based on oxides, its content by mass percentage is preferably 1% or less.

[0129] When glass plates are used as window materials, the composition is expressed as a molar percentage based on oxides, and more preferably as follows.

[0130] SiO2 55-80%

[0131] Al2O3 0–15%

[0132] SiO2 + Al2O3 55–90%

[0133] B2O3 0-15%

[0134] MgO 0-20%

[0135] CaO 0-20%

[0136] SrO 0-15%

[0137] BaO 0-15%

[0138] MgO + CaO 0–30%

[0139] MgO + CaO + SrO + BaO 0–30%

[0140] Li2O 0-20%

[0141] Na2O 0-20%

[0142] K2O 0-20%, and

[0143] R₂O (R = alkali metal element) 0–20%

[0144] The following is an explanation of each component.

[0145] SiO2 and Al2O3 are components that help improve Young's modulus, thus easily ensuring the strength required for window materials used in architectural, automotive, and other applications.

[0146] From the perspective of ensuring weather resistance and preventing excessive thermal cracking due to an excessively high average coefficient of linear expansion, the SiO2 content is preferably 55% or more, more preferably 57% or more, further preferably 60% or more, even more preferably 63% or more, even more preferably 65% ​​or more, particularly preferably 68% or more, and most preferably 70% or more. Furthermore, from the perspective of preventing increased viscosity during glass melting and facilitating glass manufacturing, its content is preferably 80% or less, more preferably 78% or less, further preferably 75% or less, and most preferably 74% or less.

[0147] Al2O3 is a component that ensures weather resistance and prevents thermal cracking due to an excessively high average coefficient of linear expansion. It can be omitted, but when present, it is preferably 0.01% or more, more preferably 0.05% or more, and even more preferably 0.1% or more. Furthermore, to prevent an increase in viscosity during glass melting, the glass viscosity is set to 10. 2 The temperature (hereinafter referred to as T2) of dPa·s, and the glass viscosity are 10 4 From the perspective of keeping the temperature (hereinafter referred to as T4) low (dPa·s) to facilitate glass manufacturing, and further from the perspective of ensuring good radio wave transmission characteristics, its 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.

[0148] From the perspective of obtaining good radio wave transmittance, the total content of SiO2 and Al2O3 (SiO2+Al2O3) is preferably 55% to 90%. Furthermore, from the perspective of ensuring weather resistance and preventing the average coefficient of linear expansion from becoming too large, the total content is more preferably 57% or more, further preferably 60% or more, even more preferably 65% ​​or more, particularly preferably 70% or more, and most preferably 72% or more. In addition, from the perspective of keeping T2 and T4 low and facilitating glass manufacturing, the total content is more preferably 85% or less, further preferably 80% or less, even more preferably 78% or less, and particularly preferably 75% or less.

[0149] B2O3 is a component that improves solubility, glass strength, and electromagnetic transmittance. However, it is also a component where alkali elements tend to volatilize during melting and forming, potentially leading to a deterioration in glass quality. Furthermore, if present in excess, its average coefficient of linear expansion decreases, 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, even more preferably 3% or less, particularly preferably 1% or less, and most preferably substantially absent. Here, "substantially absent" means that B2O3 is not present except in cases where it is unavoidably introduced as an impurity.

[0150] MgO is a component that promotes the melting of glass raw materials and improves weather resistance. On the other hand, from the perspective of preventing devitrification and improving radio wave transmittance, the content of MgO is preferably 20% or less, more preferably 15% or less, further preferably 8% or less, even more preferably 4% or less, particularly preferably 1% or less, most preferably 0.5% or less, or may be absent.

[0151] CaO, SrO, and BaO are components that can reduce the dielectric loss tangent of glass and improve its solubility; one or more of them may be present.

[0152] The glass may be free of CaO, but when CaO is present, its content is preferably 3% or more, more preferably 6% or more, further preferably 8% or more, even more preferably 10% or more, and particularly preferably 11% or more, to reduce the dielectric loss of the glass and thus increase its radiometric transmittance, as well as to improve its solubility (reducing T2 and T4). Furthermore, to avoid increasing the specific gravity of the glass and to maintain low brittleness and strength, its content is preferably 20% or less, and to further reduce brittleness, it is more preferably 15% or less, further preferably 14% or less, even more preferably 13% or less, and particularly preferably 12% or less.

[0153] From the perspective of avoiding an increase in glass specific gravity and maintaining low brittleness and strength, the SrO content is preferably 15% or less, more preferably 8% or less, further preferably 3% or less, even more preferably 1% or less, and particularly preferably substantially free of SrO. Here, substantially free of SrO means free of SrO except in cases where it is unavoidably mixed in as an impurity.

[0154] From the perspective of avoiding an increase in glass specific gravity and maintaining low brittleness and strength, the BaO content is preferably 15% or less, more preferably 5% or less, further 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 free of BaO except in cases where it is unavoidably mixed in as an impurity.

[0155] The total content of MgO, CaO, SrO, and BaO (MgO+CaO+SrO+BaO) can be 0% (not contained), but from the perspective of reducing glass viscosity during manufacturing, reducing T2 and T4, or increasing Young's modulus, it is preferable to be more than 0%, more preferably 0.5% or more, further preferably 5% or more, even more preferably 8% or more, particularly preferably 10% or more, and most preferably 11% or more. Furthermore, from the perspective of improving weather resistance, the total content is preferably 30% or less, more preferably 17% or less, further preferably 16% or less, even more preferably 15% or less, particularly preferably 14% or less, and most preferably 13% or less.

[0156] Furthermore, to prevent devitrification during glass melting and forming, which would lead to a 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. Alternatively, the total content may be 0% (not containing any MgO), but from the perspective of preventing excessively high glass viscosity during melting and forming, which would make manufacturing difficult, it 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.

[0157] Li₂O is a component that improves the solubility of glass and easily increases Young's modulus, thus contributing to improved glass strength. While Li₂O may not be present, its presence allows for chemical strengthening and can sometimes improve electromagnetic transmittance. Therefore, when Li₂O is present, its content is preferably 0.1% or more, more preferably 1% or more, further preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. Furthermore, due to concerns about devitrification or phase separation during glass manufacturing, making manufacturing difficult, its content is preferably 20% or less, more preferably 16% or less, further preferably 12% or less, even more preferably 8% or less, particularly preferably 7% or less, and most preferably 6.5% or less.

[0158] Na₂O and K₂O are components that improve the solubility of glass. By containing at least 0.1% of either one, it is easy to suppress T₂ to below 1750°C and T₄ to below 1350°C. However, if the combined content of Na₂O and K₂O is low, there are concerns that the average coefficient of linear expansion cannot be increased, hindering thermal strengthening. Therefore, by including both Na₂O and K₂O, weather resistance can be improved while maintaining solubility. Furthermore, it is sometimes effective in improving radio wave transmittance.

[0159] It may not contain Na2O, but by including Na2O, in addition to the effects mentioned above, chemical strengthening can be achieved. Therefore, its content is preferably 0.1% or more, more preferably 1% or more, further preferably 3% or more, even more preferably 5% or more, and particularly preferably 6% or more. In addition, from the viewpoint of preventing the average coefficient of linear expansion from becoming too large and easily causing thermal cracking, its content is preferably 20% or less, more preferably 16% or less, further preferably 14% or less, even more preferably 12% or less, particularly preferably 10% or less, and most preferably 8% or less.

[0160] It may be possible to omit K2O, but the aforementioned effects can be achieved by including K2O. Therefore, its content is preferably 0.1% or more, more preferably 0.9% or more, further preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. Furthermore, from the perspective of preventing the average coefficient of linear expansion from becoming too large and thus easily causing thermal cracking, and preventing a decrease in weather resistance, its content is preferably 20% or less, more preferably 16% or less, further preferably 14% or less, even more preferably 12% or less, particularly preferably 10% or less, and most preferably 8% or less. It should be noted that from the viewpoint of radio wave transmittance, high radio wave transmittance can also be obtained by keeping the K2O content within the above range.

[0161] Thus, by setting the content of Na2O and K2O within the aforementioned range, the average coefficient of thermal expansion can be adjusted to the desired value, making it suitable as a window material with good integration with other components such as black ceramics and intermediate films.

[0162] R2O represents the total amount of alkali metal oxides. The presence of alkali metal oxides such as Rb2O and Cs2O in glass is rare; therefore, R2O usually refers to the total content of Li2O, Na2O, and K2O (Li2O + Na2O + K2O).

[0163] It may also be free of alkali metal oxides, but alkali metal oxides reduce the viscosity of glass during manufacturing and lower the content of T2 and T4. Therefore, their total content is preferably more than 0%, more preferably 1% or more, further preferably 5% or more, even more preferably 6% or more, even more preferably 8% or more, particularly preferably 10% or more, particularly preferably 11% or more, and particularly preferably 12% or more. In addition, from the viewpoint of improving weather resistance, the total content is preferably 20% or less, more preferably 19% or less, further 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.

[0164] When alkali metal oxides are included, Na₂O is preferred. From the perspective of sufficiently reducing the dielectric loss tangent, the molar ratio expressed as (Na₂O / R₂O) is more preferably 0.01 or more, and even more preferably 0.98 or less. The molar ratio is further preferably 0.05 or more, even more preferably 0.1 or more, even more preferably 0.2 or more, particularly preferably 0.3 or more, and most preferably 0.4 or more. Furthermore, this molar ratio is further 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.

[0165] When alkali metal oxides are included, K₂O is preferably also included. From the perspective of fully obtaining the effect of improving radio wave transmittance, the molar ratio expressed as (K₂O / R₂O) is more preferably 0.01 or more, and even more preferably 0.98 or less. The molar ratio is further preferably 0.05 or more, even more preferably 0.1 or more, even more preferably 0.2 or more, particularly preferably 0.3 or more, and most preferably 0.4 or more. In addition, this molar ratio is further preferably 0.8 or less, even more preferably 0.6 or less, and particularly preferably 0.55 or less.

[0166] From the perspective of improving electromagnetic wave transmittance, the product of the total content of alkali metal oxides (R2O, %) and the content of MgO (%) (R2O×MgO, %) 2 The preferred concentration is reduced. (R₂O×MgO) is preferably 100%. 2 The following is preferred: 80% 2 The following is a further preferred value of 66%. 2 The following is a further preferred option: 60%. 2 The following is a further preferred option: 50%. 2 The following is particularly preferred: 40%. 2 The preferred value is 30%. 2 The following. Furthermore, from the perspective of improving glass production efficiency, 1% is preferred. 2 The above, more preferably 3%, is preferred.2 The above is further preferred to be 5%. 2 the following.

[0167] 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, there are concerns about an increase in the liquidus temperature. 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 non-existent. Here, substantially non-existent means that ZrO2 is not present except in cases where it is unavoidably mixed in as an impurity.

[0168] From the perspective of being able to manufacture glass sheets using readily available glass raw materials and easily ensuring the weather resistance of the glass sheets, the total content of the above-mentioned components, expressed as (SiO2+Al2O+MgO+CaO+SrO+BaO+Li2O+Na2O+K2O), is preferably 85% or more, more preferably 88% or more, further preferably 90% or more, even more preferably 92% or more, even more preferably 95% or more, particularly preferably 98% or more, and most preferably 99.5% or more. Alternatively, the total content may be 100%, but considering the addition of colorants, clarifying agents, etc., to the glass sheet, it is more preferably 99.9% or less.

[0169] To improve the clarity of the glass plate, it may contain at least one component selected from SnO2, Cl, and SO3. When the total content of the main components SiO2, Al2O3, RO, and R2O (SiO2+Al2O3+RO+R2O) is set to 100% as a mass percentage based on oxides, their total content (SnO2+Cl+SO3) can be 0.01 to 1.0% by mass. The total content is preferably 0.80% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less. Furthermore, the total content is preferably 0.02% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.10% by mass or more.

[0170] The preferred configurations for glass plates used as substrates for high-frequency devices are as follows: glass transition temperature Tg, T2, T4, devitrification temperature, Young's modulus, acid resistance, alkali resistance, coefficient of thermal expansion (average coefficient of thermal expansion), strain point, density, plate thickness, and area of ​​the main surface.

[0171] From the perspective of preventing substrate deformation during the fabrication process of high-frequency devices, the glass transition temperature Tg is preferably 580°C or higher, more preferably 600°C or higher. Furthermore, from the perspective of facilitating the manufacture of the glass plate, it is preferably 750°C or lower, more preferably 720°C or lower. It should be noted that the glass transition temperature Tg is a value measured according to JIS R 3103-3:2001.

[0172] From the perspective of facilitating the manufacture of glass sheets, T2 is preferably below 1950°C, more preferably below 1700°C. Furthermore, from the perspective of reducing convection of molten glass and minimizing damage to glass melting equipment, T2 is preferably above 1500°C.

[0173] From the perspective of protecting the manufacturing equipment, T4 is preferably below 1350°C, and more preferably below 1300°C. Furthermore, if the heat introduced into the forming equipment by the glass decreases, it is necessary to increase the heat input into the forming equipment; therefore, T4 is preferably above 1100°C.

[0174] It should be noted that T2 and T4 are values ​​measured using a rotary high-temperature viscometer.

[0175] From the perspective of reducing the component temperature of the forming equipment and extending the component life during glass plate forming, the devitrification temperature is preferably below 1350°C, and more preferably below 1300°C. Furthermore, the lower limit of the devitrification temperature is not particularly limited and can be above 1000°C or above 1050°C. It should be noted that the devitrification temperature is the average of the highest temperature at which crystals precipitate on the glass surface and inside the glass, and the lowest temperature at which crystals do not precipitate, observed through an optical microscope after heat treatment of 17 hours in an electric furnace at a controlled temperature with crushed glass particles placed in a platinum dish.

[0176] From the perspective of suppressing the amount of deflection during the manufacturing process of supplying glass plates to high-frequency devices, the Young's modulus is preferably 50 GPa or higher, more preferably 55 GPa or higher. Furthermore, there is no particular upper limit to the Young's modulus, and it can be 100 GPa or lower. It should be noted that the Young's modulus is a value measured using an ultrasonic pulse Young's modulus measuring device.

[0177] Acid resistance refers to the amount of glass component leached per unit surface area when a glass plate is immersed in an acidic aqueous solution (6 wt% HNO3 + 5 wt% H2SO4, 45°C) for 170 seconds. To prevent surface roughness during cleaning with acid solutions, the preferred leaching amount for acid resistance is 0.05 g / cm³. 2 The following is a further preferred value: 0.03 g / cm³ 2 The lower limit of dissolution is not specifically limited and can be above 0.001 g / cm2.

[0178] Alkali resistance refers to the amount of glass component leached per unit surface area when a glass plate is immersed in an alkaline aqueous solution (1.2 wt% NaOH, 60°C) for 30 minutes. To prevent surface roughness during cleaning with an alkaline solution, the leaching amount, indicating alkali resistance, is preferably 0.10 g / cm³. 2 The following is a further preferred value: 0.08 g / cm³ 2 The following is a general rule regarding the lower limit of dissolution; it is not specifically defined and can be 0.001 g / cm³. 2 above.

[0179] The coefficient of thermal expansion is the average value measured by a dilatometer over a temperature range of 50–350°C. From the perspective of more appropriately adjusting the difference in thermal expansion coefficients with other components when used in semiconductor packaging for high-frequency devices, an average coefficient of thermal expansion of 20 × 10⁻⁶ is preferred. -7 (K -1 ) or more, preferably 25×10 -7 (K -1 The above is also true. Furthermore, the average coefficient of thermal expansion is preferably 60 × 10⁻⁶. -7 (K -1 ) or less, preferably 50×10 -7 (K -1 )the following.

[0180] From the perspective of heat resistance, the strain point is preferably 500°C or higher, more preferably 550°C or higher. Furthermore, from the perspective of ease of mitigation, it is preferably 800°C or lower. The strain point is a value measured according to JIS R 3103-2 (2001).

[0181] For lightweight design, a density of 2.8 g / cm³ is preferred. 3 The lower limit of density is not specifically defined and can be 2.0 g / cm³. 2 The above should be noted. The density is a value determined using the Archimedes method.

[0182] From the perspective of ensuring the strength of the substrate, the board 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 addition, from the perspective of thinning, miniaturization, and improved production efficiency, it 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.

[0183] When a glass plate is used as a substrate for high-frequency devices, the area of ​​the main surface of the glass plate is preferably 80 cm². 2 The above, preferably 350cm 2The above, preferably 500cm 2 The above, preferably 1000cm 2 The above, preferably 1500cm 2 The above and the following are particularly preferred to be 2000cm. 2 Above, 2500cm 2 Above, 3000cm 2 Above, 4000cm 2 Above, 6000cm 2 Above, 8000cm 2 Above, 12000cm 2 Above, 16000cm 2 Above, 20000cm 2 Above, 25000cm 2 That's all. On the other hand, the area of ​​the main surface of the substrate is typically preferably 5,000,000 cm². 2 Below. Even with this area, the in-plane distribution of the dielectric loss tangent is small, and the glass plate is homogeneous. Therefore, it can be applied to the manufacture of large-area high-frequency devices, which was previously impossible, and windows that allow high frequencies to pass through. The area of ​​the main surface of the substrate is more preferably 100,000 cm². 2 Below, 80000cm is more preferred. 2 The following is a further preferred value: 60000cm 2 The following is particularly preferred: 50000cm 2 The following is a further preferred size: 40000cm 2 The optimal value is 30000cm. 2 the following.

[0184] The preferred configurations for the glass plates used as window materials are as follows: glass transition temperature Tg, T2, T4, devitrification temperature, Young's modulus, acid resistance, alkali resistance, coefficient of thermal expansion (average coefficient of thermal expansion), strain point, density, plate thickness, and area of ​​the main surface. It should be noted that the methods for measuring each property are the same as those used for measuring the properties of the substrates used in the aforementioned high-frequency devices.

[0185] From the viewpoint of glass bending, the glass transition temperature Tg is preferably 500°C or higher, more preferably 520°C or higher. Furthermore, from the perspective of air-cooling strengthening, it is preferably 620°C or lower, more preferably 600°C or lower.

[0186] From the perspective of facilitating the manufacture of glass sheets, T2 is preferably below 1550°C, and more preferably below 1480°C. Furthermore, from the perspective of reducing convection of molten glass and minimizing damage to glass melting equipment, T2 is preferably above 1250°C.

[0187] From the perspective of protecting the manufacturing equipment, T4 is preferably below 1200°C, and more preferably below 1100°C. Furthermore, if the heat introduced into the forming equipment by the glass decreases, it is necessary to increase the heat input into the forming equipment; therefore, T4 is preferably above 900°C.

[0188] From the perspective of reducing the component temperature of the forming equipment and extending the component life during glass sheet forming, the devitrification temperature is preferably below 1100°C, and more preferably below 1000°C. Furthermore, the lower limit of the devitrification temperature is not particularly limited and can be above 900°C.

[0189] From the perspective of suppressing deflection, the Young's modulus is preferably 50 GPa or higher, more preferably 55 GPa or higher. Furthermore, there is no particular upper limit to the Young's modulus, and it can be 100 GPa or lower.

[0190] Regarding acid resistance, to prevent surface roughness when cleaning the glass surface with acid solutions, the leaching amount described above is preferably 0.1 g / cm³. 2 The following is a further preferred value: 0.05 g / cm³ 2 The following applies. Additionally, there is no specific limit to the lower limit of dissolution; it can be 0.001 g / cm³. 2 above.

[0191] Regarding alkali resistance, to prevent the glass surface from becoming rough when cleaned with alkaline solutions, the leaching amount mentioned above is preferably 0.20 g / cm³. 2 The following is a further preferred value: 0.10 g / cm³ 2 The following applies. Additionally, there is no specific limit to the lower limit of dissolution; it can be 0.001 g / cm³. 2 above.

[0192] Similarly, the coefficient of thermal expansion is used as the average value over a temperature range of 50–350°C. From the perspective of facilitating air-cooling enhancement, an average coefficient of thermal expansion of 60 × 10⁻⁶ is preferred. -7 (K -1 ) or above, more preferably 70×10 -7 (K -1 The above is true. Furthermore, if the average coefficient of thermal expansion is too large, it will not withstand thermal shock; therefore, a coefficient of 130 × 10⁻⁶ is preferred. -7 (K -1 Below 110×10, the preferred size is 110×10. -7 (K -1 )the following.

[0193] From the perspective of heat resistance, the strain point is preferably 450°C or higher, more preferably 500°C or higher. Furthermore, from the perspective of ease of mitigation, it is preferably 700°C or lower. The strain point is the value measured according to JIS R 3103-2 (2001).

[0194] If the density increases, the weight becomes heavier, making handling more difficult. Therefore, a density of 2.8 g / cm³ is preferred. 3 The following is a separate point. Additionally, there is no specific lower limit for density; it can be 2.0 g / cm³. 2 above.

[0195] From the perspective of ensuring the rigidity of the window material, the thickness is preferably 1.0 mm or more, and more preferably 1.5 mm or more. Furthermore, from the perspective of weight reduction, it is preferably 6.0 mm or less, and more preferably 5.0 mm or less.

[0196] When using glass panels as window materials, the preferred area of ​​the main surface of the glass panel is 350 cm². 2 The above, preferably 500cm 2 The above, preferably 1000cm 2 The above, preferably 1500cm 2 The above and the following are particularly preferred to be 2000cm. 2 Above, 2500cm 2 Above, 3000cm 2 Above, 4000cm 2 Above, 6000cm 2 Above, 8000cm 2 Above, 12000cm 2 Above, 16000cm 2 Above, 20000cm 2 Above, 25000cm 2 above.

[0197] On the other hand, the area of ​​the main surface of the window material is usually 6,000,000 cm². 2 The following applies. 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 is suitable for manufacturing large-area high-frequency devices and windows that allow high-frequency transmission, which were previously impossible. To ensure the homogeneity of the glass plate, controlling the area of ​​the main surface is appropriate; therefore, the area of ​​the main surface of the window material is more preferably 100,000 cm². 2 Below, 80000cm is more preferred. 2 The following is a further preferred value: 60000cm 2 The following is particularly preferred: 50000cm 2 The following is a further preferred size: 40000cm2 The optimal value is 30000cm. 2 the following.

[0198] Both tanδA and εrA are preferably small. This allows for applications in large-area high-frequency devices and windows that allow high frequencies to pass through, which were previously impossible to achieve. tanδA is preferably 0.009 or less, more preferably 0.008 or less, 0.007 or less, 0.006 or less, 0.005 or less, further 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.

[0199] Regarding the lower limit of tanδA, there is no particular limitation. From the viewpoint of practicality in glass plate manufacturing, it is preferably 0.0001 or higher, more preferably 0.0004 or higher, even more preferably 0.0006 or higher, even more preferably 0.0008 or higher, and most preferably 0.001 or higher. εrA is preferably 6.8 or lower, and subsequently more preferably 6.5 or lower, 6.0 or lower, 5.5 or lower, 5.2 or lower, 4.9 or lower, even more preferably 4.7 or lower, particularly preferably 4.5 or lower, even more preferably 4.4 or lower, and most preferably 4.3 or lower.

[0200] There is no particular limitation on the lower limit of εrA. From the point of view of the practicality of glass plate manufacturing, it is 3.5 or more, more preferably 3.6 or more, further preferably 3.7 or more, particularly preferably 3.8 or more, further preferably 3.9 or more, and most preferably 4.0 or more.

[0201] <Methods for manufacturing glass plates>

[0202] The glass plate manufacturing method of this embodiment includes the following steps in sequence: a melting and forming step, in which glass raw materials are melted and the resulting molten glass is formed into a plate shape; a cooling step, in which the molten glass formed into a plate shape is cooled to a temperature below (Tg-300)°C relative to the glass transition temperature Tg (°C) to obtain a glass blank; and a heat treatment step, in which the obtained glass blank is heated from a temperature below (Tg-300)°C to a range of (Tg-100)°C to (Tg+50)°C without exceeding (Tg+50)°C and then cooled again to below (Tg-300)°C.

[0203] Perform the above heat treatment process once, twice, or three or more times.

[0204] The above heat treatment process involves the glass blank being heated to a temperature exceeding (Tg-300)℃, then passing through a maximum temperature Temax℃ within the range of (Tg-100)℃ to (Tg+50)℃, until it falls below (Tg-300)℃ again.

[0205] In the entire heat treatment process described above, the total time during which the temperature of the glass blank is in the range of (Tg-100)℃~(Tg+50)℃ is more than or equal to K (minutes) of the highest temperature Tmax℃ of the glass blank used in the entire heat treatment process described above, expressed by the following formula (1).

[0206] In each of the above heat treatment processes, if the time from the last moment of cooling down from the highest temperature Temax℃ to the moment when (Tg-110)℃ is set as t1 (minutes), the following equation (2) is satisfied.

[0207] K = [{(Tg+50)-Tmax} / 10]+15 Equation (1)

[0208] {Temax-(Tg-110)} / t1≤10 Equation (2)

[0209] Thus, the glass plate described in the above-mentioned "Glass Plate" can be obtained.

[0210] (Melting and molding processes)

[0211] The melting and forming process involves melting glass raw materials and forming the resulting molten glass into a plate shape. However, conventionally known methods can be used, and there are no particular limitations. An example is shown below.

[0212] Glass raw materials are prepared in a manner that constitutes the target glass plate. The raw materials are continuously fed into a melting furnace and preferably heated to about 1450-1750°C to obtain molten glass.

[0213] Raw materials can also include oxides, carbonates, nitrates, sulfates, hydroxides, chlorides, and other halides. In cases where molten glass comes into contact with platinum during the melting and refining processes, tiny platinum particles may dissolve into the molten glass and become foreign matter mixed into the resulting glass sheet. However, the use of nitrate raw materials can prevent the formation of platinum foreign matter.

[0214] As nitrates, strontium nitrate, barium nitrate, magnesium nitrate, and calcium nitrate can be used. Strontium nitrate is preferred. The raw material particle size can be appropriately adjusted, ranging from larger particles of several hundred μm that do not produce melting residue to smaller particles of several μm that do not scatter during transport and do not agglomerate into secondary particles. Granulated materials can also be used. To prevent raw material scattering, the moisture content of the raw material can be appropriately adjusted. The redox degree of β-OH and Fe (redox ratio {Fe...}) can also be appropriately adjusted. 2+ / (Fe 2+ +Fe 3+It is used under melting conditions such as )})

[0215] Next, a clarification process can be performed to remove air bubbles from the resulting molten glass. This clarification process can be carried out using a defoaming method performed under reduced pressure, or by setting a temperature higher than the melting temperature of the raw material. SO3 or SnO2 can be used as the clarifying agent.

[0216] The preferred source of SO3 is a sulfate selected from at least one element chosen from Al, Li, Na, K, Mg, Ca, Sr, and Ba. Alkali metal sulfates are more preferred, especially Na2SO4, which has a significant bubble-generating effect and good initial solubility. Alkali earth metal sulfates are also acceptable, with CaSO4·2H2O, SrSO4, and BaSO4 being more preferred as they have a significant bubble-generating effect.

[0217] Halogens such as Cl or F are preferred as clarifying agents in defoaming processes carried out under reduced pressure.

[0218] As a Cl source, chlorides selected from at least one element from Al, Mg, Ca, Sr and Ba are preferred, and chlorides of alkaline earth metals are more preferred. Among them, SrCl2·6H2O and BaCl2·2H2O have a significant effect on increasing bubbles and have low deliquescence, and are therefore particularly preferred.

[0219] As the source of fluoride, it is preferably a fluoride selected from at least one element selected from Al, Na, K, Mg, Ca, Sr and Ba, and more preferably an alkaline earth metal fluoride, wherein CaF2 has a significant effect on increasing the solubility of glass raw materials, and is more preferably a fluoride.

[0220] Tin compounds, represented by SnO2, generate O2 gas in molten glass. In molten glass, SnO2 is reduced to SnO at temperatures above 1450°C, producing O2 gas, which increases the size of bubbles and promotes their growth. During glass sheet manufacturing, the glass raw material is heated to approximately 1450–1750°C for melting, thus allowing the bubbles in the molten glass to grow more effectively.

[0221] Next, a forming process is carried out to form a glass ribbon by shaping molten glass, preferably molten glass in which bubbles have been removed by a clarification process, into a plate shape.

[0222] As a forming process, known methods for forming glass into sheet shapes can be applied, such as the float glass method, which involves pouring molten glass onto molten metals like tin to form a sheet, the overflow pull method (melting method), which involves pouring molten glass downwards from a gutter-shaped component, and the slit pull method, which involves pouring molten glass downwards from a slit.

[0223] It should be noted that the molten glass can also be supplied directly to the subsequent cooling process without being formed into a plate.

[0224] (Cooling process)

[0225] The molten glass obtained in the above forming process is cooled to a temperature below (Tg-300)°C relative to the glass transition temperature Tg (°C) to obtain a glass preform. The average cooling rate is not particularly limited and any average cooling rate can be used, but for example, from the perspective of preventing glass devitrification, a rate of 10°C / min or more is preferred, and 40°C / min or more is more preferred. Furthermore, from the perspective of preventing strain in the glass during the cooling process, a rate of 1000°C / min or less is preferred, and 100°C / min or less is more preferred. Additionally, the average cooling rate from (Tg+50)°C to (Tg-100)°C is preferably greater than 10°C / min, and more preferably 15°C / min or more.

[0226] It should be noted that the average cooling rate refers to the average value calculated from the refractive index when the cooling rates of the central part and the ends of the glass plate are different. It should also be noted that the cooling rates of the central part and the ends can be determined separately from the refractive index.

[0227] (Heat treatment process)

[0228] After the above cooling process, the obtained glass blank is subjected to heat treatment, which involves heating from a temperature below (Tg-300) to a range of (Tg-100) to (Tg+50)℃ without exceeding (Tg+50)℃, and then cooling down to below (Tg-300)℃. This heat treatment process may be performed once, twice, or more than three times.

[0229] The first heat treatment process involves the glass blank being heated to a temperature exceeding (Tg-300)℃, then passing through a maximum temperature Temax℃ within the range of (Tg-100)℃ to (Tg+50)℃, until it falls below (Tg-300)℃ again.

[0230] In a single heat treatment process, there is no particular limitation on the heating rate from (Tg-300)℃ until it reaches the range of (Tg-100)℃~(Tg+50)℃. Furthermore, before reaching the range of (Tg-100)℃~(Tg+50)℃, repeated heating and cooling can be performed, or the temperature can be maintained at a certain level.

[0231] In the overall heat treatment process, the total time during which the temperature of the glass blank is in the range of (Tg-100)℃~(Tg+50)℃ is more than or equal to the highest temperature Tmax℃ of the glass blank in the overall heat treatment process, expressed by the following formula (1) in K (minutes).

[0232] K = [{(Tg+50)-Tmax} / 10]+15 Equation (1)

[0233] Here, when there are two or more heat treatment processes, the total time for the glass blank temperature to remain within the range of (Tg-100)℃~(Tg+50)℃ refers to the sum of the time for the first heat treatment process and the time for subsequent heat treatment processes within the range of (Tg-100)℃~(Tg+50)℃. If the total time for the glass blank temperature to remain within the range of (Tg-100)℃~(Tg+50)℃ is K (minutes) or more, the electromagnetic wave transmittance is improved.

[0234] The total time for which the temperature of the glass blank is in the range of (Tg-100)℃ to (Tg+50)℃ is preferably (K+5) minutes or more, more preferably (K+10) minutes or more. There is no particular upper limit, but for good 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.

[0235] The temperature distribution of the glass blank is not particularly limited as long as the total time within the range of (Tg-100)℃ to (Tg+50)℃ is K (minutes) or more. That is, the temperature can be raised to the range of (Tg-100)℃ to (Tg+50)℃ during one heat treatment process, then cooled to a temperature exceeding (Tg-300)℃ but less than (Tg+50)℃, and then raised again to the range of (Tg-100)℃ to (Tg+50)℃, and so on, and the heating and cooling can be repeated. Alternatively, the temperature can be maintained at a certain level.

[0236] To improve radio wave transmittance, the lower limit of the above-mentioned temperature range is (Tg-100)℃, preferably (Tg-90)℃ or higher, and more preferably (Tg-80)℃ or higher. Furthermore, to prevent glass deformation, the upper limit of the temperature range is (Tg+50)℃, preferably (Tg+40)℃ or lower, and more preferably (Tg+35)℃ or lower.

[0237] In each heat treatment process, if the time from the last moment of cooling down from the highest temperature Temax℃ to the moment when (Tg-110)℃ is set as t1 (minutes), the following equation (2) is satisfied. It should be noted that when there is one heat treatment process, Temax℃ is the same as Tmax℃ mentioned above. When there are two or more heat treatment processes, the highest temperature among the two or more Temax℃ is Tmax℃ mentioned above.

[0238] {Temax-(Tg-110)} / t1≤10 Equation (2)

[0239] The temperature distribution of glass blanks varies. In addition to the above-mentioned cases where the temperature is raised to the range of (Tg-100)℃~(Tg+50)℃ and then cooled to a temperature exceeding (Tg-300)℃ but less than (Tg+50)℃, and then raised again to the range of (Tg-100)℃~(Tg+50)℃, there are also cases where the temperature changes due to raising or lowering the temperature within the range of (Tg-100)℃~(Tg+50)℃, and cases where the temperature is maintained at a certain level within the range of (Tg-100)℃~(Tg+50)℃, etc.

[0240] In these various temperature distributions, if the maximum temperature Temax℃ is reached only once, the last moment when the temperature begins to drop from the maximum temperature Temax℃ refers to that moment. Furthermore, if it is reached more than once, it refers to the moment of the last drop. Moreover, if the maximum temperature Temax℃ is maintained for a certain period, it refers to the last moment when that maintenance ends.

[0241] The same applies to the moment when the temperature finally crosses (Tg-110)℃. That is, the temperature can be repeatedly raised or lowered from the final moment of cooling from the highest temperature Temax℃ until it drops below (Tg-300)℃, or it can be maintained at a certain temperature. If the temperature crosses (Tg-110)℃ once during the cooling process below (Tg-300)℃, the moment when the temperature finally crosses (Tg-110)℃ refers to the moment when it crosses (Tg-110)℃. If the temperature rises again after crossing (Tg-110)℃ once, exceeds (Tg-110)℃, and then drops again, the moment when the temperature finally crosses (Tg-110)℃ during the final cooling process refers to the moment when the temperature finally crosses (Tg-110)℃. Furthermore, if the temperature is maintained at (Tg-110)℃ for a certain period, the moment when the maintenance ends refers to the final moment when the temperature is maintained at that temperature.

[0242] There are no particular limitations on the temperature distribution in heat treatment processes other than those mentioned above.

[0243] In each heat treatment process, from the perspective of shortening the manufacturing process, it is preferable that the temperature of the glass blank drops from the highest temperature Temax℃ and first falls below (Tg-110)℃, and then does not exceed (Tg-110)℃ again.

[0244] In addition, in each heat treatment process, any two times from the last moment of cooling down from the highest temperature Temax℃ to the moment when (Tg-110)℃ is set as t2 (minute) and t3 (minute), and t2<t3, the time difference between t2 and t3 is more than 1 minute, and the temperature of the glass blank at t2 is set as Te2, and the temperature of the glass blank at t3 is set as Te3, preferably satisfying the following formula (3).

[0245] (Te2-Te3) / (t3-t2)≤10 Formula (3)

[0246] In the above formula (3), it means that the cooling rate at the above time t1 will not be too fast. By satisfying the relationship of formula (3), sufficient heat treatment time can be ensured, and therefore it is preferred.

[0247] The value represented by (Te2-Te3) / (t3-t2) is more preferably 9 or less, and even more preferably 8 or less. The lower limit is not particularly limited, but can be 0.1 or more to prevent the time spent manufacturing the glass sheet from becoming too long.

[0248] In the final heat treatment process, when the average cooling rate of the central portion of the glass blank, which is cooled from the highest temperature Temax °C to below (Tg-300) °C, is set as VC ( °C / min), and the average cooling rate of the ends is set as VE ( °C / min), the closer the ratio expressed by VC / VE is to 1, the better from the perspective of making the obtained glass plate more homogeneous. Specifically, it is preferably 0.8 or more, more preferably 0.9 or more, and preferably 1.2 or less, more preferably 1.1 or less, and most preferably 1.

[0249] The glass plate of this embodiment is obtained by directly cooling the glass blank, which has been cooled to below (Tg-300)°C during the heat treatment process, to room temperature (e.g., to below 50°C).

[0250] There are no particular limitations on the conditions for cooling to room temperature. For example, the average cooling rate from (Tg-300)℃ to 50℃ is preferably 0.5℃ / min or more, and preferably 50℃ / min or less. Alternatively, natural cooling can be carried out without temperature management.

[0251] It should be noted that the method for manufacturing the glass plate is not limited to the above-described embodiments, and variations and improvements within the scope of achieving the purpose of the present invention are included in the present invention.

[0252] For example, when manufacturing glass sheets, a pressure molding method can be used to directly form molten glass into a sheet shape. Furthermore, after obtaining the glass sheets, they can undergo any treatment or processing, such as air-cooling strengthening, chemical strengthening, and grinding.

[0253] In the melting and refining of glass raw materials, melting tanks and / or refining tanks can be made of refractory materials or crucibles made of platinum or platinum-based alloys (hereinafter referred to as "platinum crucibles").

[0254] The melting process using a platinum crucible involves preparing the raw materials in a manner that constitutes the composition of the resulting glass plate. The platinum crucible containing the raw materials is heated in an electric furnace, preferably to approximately 1450°C to 1700°C. Then, a platinum stirrer is inserted and stirred for 1 to 3 hours to obtain molten glass.

[0255] In the forming process of manufacturing glass plates using platinum crucibles, molten glass can also be poured onto, for example, a carbon plate or a mold frame to form a plate or block.

[0256] By using the glass plate obtained in this way as a substrate for high-frequency devices, the propagation loss of high-frequency signals can be reduced, thereby improving the quality, strength, and other characteristics of high-frequency signals. Therefore, the substrate made of this glass plate is suitable for high-frequency devices that process high-frequency signals above 3.0 GHz, as well as high-frequency devices that process signals in various high-frequency bands such as 3.5 GHz and above, 10 GHz and above, 30 GHz and above, and 35 GHz and above.

[0257] As for high-frequency devices, there are no particular limitations. Examples include high-frequency devices (electronic devices) such as semiconductor devices used in communication devices such as mobile phones, smartphones, portable information terminals, and Wi-Fi devices; surface acoustic wave (SAW) devices; radar components such as radar transceivers; and antenna components such as liquid crystal antennas.

[0258] In addition to the above, this glass panel is also suitable as a window material for vehicles such as automobiles and buildings. That is, high-frequency devices that process the aforementioned high-frequency signals are sometimes installed inside vehicles, such as millimeter-wave radar. Furthermore, it is frequently used inside buildings, such as for communication equipment and base stations. Therefore, reducing the propagation loss of high-frequency signals in the aforementioned window material is also very useful.

[0259] When glass is used as a window material, in addition to glass sheets formed into flat shapes by means of float glass or melting glass, glass sheets can also be formed into curved shapes by means of gravity forming or pressure forming to produce curved glass sheets, which can be deformed arbitrarily according to the installation location.

[0260] Furthermore, the glass used to form the glass sheet is not particularly limited to soda-lime glass, aluminosilicate glass, or alkali-free glass; it can be selected appropriately depending on the application. Moreover, it can also be a tempered glass with a compressive stress layer on the glass surface and a tensile stress layer inside the glass. Both chemically strengthened glass and air-cooled strengthened glass (physically strengthened glass) can be used as tempered glass.

[0261] Example

[0262] The present invention will be specifically described below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0263] [Example 1~Example 4]

[0264] The glass raw material, which will be represented by composition 1 in Table 1, is added to a platinum crucible and heated in an electric furnace at 1650°C for 3 hours to melt it, obtaining molten glass. During melting, a platinum stirrer is inserted into the platinum crucible and stirred for 1 hour to homogenize the glass. The molten glass is then poured onto a carbon plate and shaped into a plate (melting and shaping process).

[0265] Subsequently, the plate-shaped molten glass is placed in an electric furnace at a temperature of approximately (Tg+50)℃ and maintained at that temperature for 1 hour. Then, it is cooled to room temperature at an average cooling rate of 1℃ / minute to obtain a glass blank (cooling process).

[0266] Next, the temperature was increased to 630°C at a rate of 10°C / minute, and held at 630°C for the time specified in "Holding Time (minutes)" in Table 2. Then, the temperature was lowered from 630°C to (Tg-300)°C in an electric furnace at the average cooling rate specified in Table 2, and then allowed to cool naturally until it reached room temperature, thus obtaining the glass plate (heat treatment process). Examples 1-3 are exemplary cases, and Example 4 is a comparative example.

[0267] The physical properties of the obtained glass plate were determined by the following operations.

[0268] The results and composition are shown together in Tables 1 and 2. In the tables, blank columns for composition indicate that no additions were made, and blank columns for physical properties indicate that no measurements were taken.

[0269] [Glass transition temperature Tg (°C)]

[0270] The glass transition temperature was measured using a thermal dilatometer (MAC, model TD5000SA) according to JIS R 3103-3:2001.

[0271] [T2, T4 (°C)]

[0272] The viscosity of the glass was determined, and T2 and T4 were calculated. Specifically, the viscosity of the glass was determined according to ASTM C965-96 (2002) using a rotational high-temperature viscometer (OPTKIGYO, RVM-550). As a standard sample, the viscosity of the glass was calibrated using MIST717a, and T2 and T4 were calculated.

[0273] [Devitrification temperature]

[0274] To determine the devitrification temperature, crushed glass particles are placed in a platinum dish and heat-treated in an electric furnace at a controlled temperature for 17 hours. The average of the highest temperature at which crystals precipitate on the surface and inside the glass and the lowest temperature at which crystals do not precipitate is obtained by observing the heat-treated sample under an optical microscope (Nikon ME600).

[0275] Young's modulus

[0276] Young's modulus was measured using an ultrasonic pulse Young's modulus measuring device (Olympus, 38DL-PAUS) according to JIS R 1602 (1995).

[0277] [Acid Resistance]

[0278] For acid resistance, the glass sample was immersed in an acidic aqueous solution (6 wt% HNO3 + 5 wt% H2SO4, 45°C) for 170 seconds, and the leaching amount of glass components per unit surface area (mg / cm²) was evaluated. 2 ).

[0279] [Alkali resistance]

[0280] For alkali resistance, the glass sample was immersed in an alkaline aqueous solution (1.2 wt% NaOH, 60°C) for 30 minutes, and the leaching amount of glass component per unit surface area (mg / cm²) was evaluated. 2 ).

[0281] Average thermal expansion coefficient

[0282] The coefficient of thermal expansion in the temperature range of 50–350 °C was determined using a TMA (manufactured by MAC, model TD5000SA) according to JIS R 3102 (1995). The average value of the linear expansion coefficient in the range of 50–350 °C was then calculated as the average coefficient of thermal expansion.

[0283] [Strain Point]

[0284] The strain point was determined according to JIS R 3103-2 (2001).

[0285] [density]

[0286] Density was determined according to JIS Z 8807 (2012).

[0287] [Dielectric loss tangent tanδ]

[0288] The dielectric loss tangent tanδA of the obtained glass plate at 10 GHz was measured using the SPDR method with a 10 GHz resonator (manufactured by OWED Corporation) according to IEC 61189-2-721 (2015).

[0289] In addition, the dielectric loss tangent tanδ100 of the glass plate after heating it to (Tg+50)℃ and cooling it to (Tg-150)℃ at 100℃ / min was also measured at 10 GHz.

[0290] In the table, Δtanδ represents the value of (tanδ100-tanδA).

[0291] [Relative permittivity εr]

[0292] The relative permittivity εrA of the obtained glass plate at 10 GHz was determined by SPDR method using a 10 GHz resonator (manufactured by OWED Corporation) according to IEC 61189-2-721 (2015).

[0293] In addition, the relative permittivity εr100 of the glass plate after being heated to (Tg+50)℃ and cooled to (Tg-150)℃ at 100℃ / min was also measured at 10 GHz.

[0294] [Table 1]

[0295] Table 1

[0296]

[0297] [Table 2]

[0298] Table 2

[0299]

[0300] [Example 5~Example 8]

[0301] Using glass raw materials with the composition indicated as composition 2 in Table 1, in the subsequent heat treatment process, the temperature was increased to 597°C at 10°C / min, and held at 597°C for the time specified in "Holding Time (minutes)" in Table 3. The temperature was then decreased to (Tg-300)°C in an electric furnace at the average cooling rate specified in Table 3. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 5 to 7 are exemplary examples, and Example 8 is a comparative example.

[0302] The physical properties of the obtained glass plates were measured under the same conditions as in Example 1. The results and compositions are shown in Tables 1 and 3.

[0303] [Table 3]

[0304] Table 3

[0305]

[0306] [Example 9~Example 12]

[0307] Using glass raw materials with the composition indicated as composition 3 in Table 1, in the subsequent heat treatment process, the temperature was increased to 653°C at 10°C / min, and held at 653°C for the time specified in "Holding Time (minutes)" in Table 4. The temperature was then decreased in an electric furnace at the average cooling rate specified in Table 4 to (Tg-300)°C. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 9 to 11 are exemplary examples, and Example 12 is a comparative example.

[0308] The physical properties of the obtained glass plates were measured under the same conditions as in Example 1. The results and compositions are shown in Tables 1 and 4.

[0309] [Table 4]

[0310] Table 4

[0311]

[0312] [Example 13~Example 16]

[0313] Using glass raw materials with the composition indicated as composition 4 in Table 1, in the subsequent heat treatment process, the temperature was increased to 675°C at 10°C / min, and held at 675°C for the time specified in "Holding Time (minutes)" in Table 5. The temperature was then decreased to (Tg-300)°C in an electric furnace at the average cooling rate specified in Table 5. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 13 to 15 are exemplary examples, and Example 16 is a comparative example.

[0314] The physical properties of the obtained glass plates were measured under the same conditions as in Example 1. The results and compositions are shown in Tables 1 and 5.

[0315] [Table 5]

[0316] Table 5

[0317]

[0318] [Example 17~Example 20]

[0319] Using glass raw materials with the composition indicated as composition 5 in Table 1, in the subsequent heat treatment process, the temperature was increased to 760°C at 10°C / min, and held at 760°C for the time specified in "Holding Time (minutes)" in Table 6. The temperature was then decreased to (Tg-300)°C in an electric furnace at the average cooling rate specified in Table 6. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 17 to 19 are exemplary cases, and Example 20 is a comparative example.

[0320] The physical properties of the obtained glass plates were measured under the same conditions as in Example 1. The results and compositions are shown in Tables 1 and 6.

[0321] [Table 6]

[0322] Table 6

[0323]

[0324] [Example 21~Example 24]

[0325] Using glass raw materials with the composition indicated as composition 6 in Table 1, in the subsequent heat treatment process, the temperature was increased to 760°C at 10°C / min, and held at 760°C for the time specified in "Holding Time (minutes)" in Table 7. The temperature was then decreased in an electric furnace at the average cooling rate specified in Table 7 to (Tg-300)°C. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 21 to 23 are exemplary examples, and Example 24 is a comparative example.

[0326] The physical properties of the obtained glass plates were measured under the same conditions as in Example 1. The results and compositions are shown in Tables 1 and 7.

[0327] [Table 7]

[0328] Table 7

[0329]

[0330] [Example 25~Example 28]

[0331] Using glass raw materials with the composition indicated as composition 7 in Table 1, in the subsequent heat treatment process, the temperature was increased to 700°C at 10°C / min, and held at 700°C for the time specified in "Holding Time (minutes)" in Table 8. The temperature was then decreased to (Tg-300)°C in an electric furnace at the average cooling rate specified in Table 8. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 25 to 27 are exemplary examples, and Example 28 is a comparative example.

[0332] The physical properties of the obtained glass plates were measured under the same conditions as in Example 1. The results and compositions are shown in Tables 1 and 8.

[0333] [Table 8]

[0334] Table 8

[0335]

[0336] [Example 29~Example 31]

[0337] Using glass raw materials with the composition shown as component 4 in Table 1, the glass is formed into plates through a glass melting furnace and forming equipment (melting and forming processes).

[0338] Subsequently, the molten glass, which will be in the form of a plate at 700°C, is cooled to room temperature at an average cooling rate of 50°C / minute through a slow cooling device, resulting in a glass blank plate of 37cm×47cm and 1.1mm thickness (cooling process).

[0339] Next, the temperature was increased to Tmax℃ in Table 9 at a rate of 10℃ / min, and held at Tmax℃ for the time specified in the "Holding Time (minutes)" section of Table 9. The temperature was then decreased to (Tg-300)℃ in an electric furnace at the average cooling rate specified in Table 9. Otherwise, the glass plate was obtained in the same manner as in Example 1. Examples 29 to 31 are examples.

[0340] It should be noted that when the average cooling rate of the central part of the glass blank is set to VC (°C / min) and the average cooling rate of the ends is set to VE (°C / min), the furnace temperature is adjusted such that the ratio expressed by VC / VE is 1.1 or less. Here, the ends of the glass blank refer to the position 10cm from the end of the glass blank.

[0341] The relative permittivity and dielectric loss tangent of the obtained glass plate were measured under the same conditions as in Example 1. Measurements were taken at four locations near the approximate center and corners of the plate, and their maximum and minimum values ​​were recorded. The results are shown in Table 9.

[0342] In addition, the minimum value of Δtanδ and the maximum value of εr100 / εrA are shown in Table 9. Furthermore, Table 9 shows the differences in tanδA and εrA at the two locations with the largest differences in tanδA among the four locations near the approximate center and corners of the plate.

[0343] [Table 9]

[0344] Table 9

[0345]

[0346] [Example 32~Example 34]

[0347] Using glass raw materials that are represented by composition 6 in Table 1, the glass is formed into plates through a glass melting furnace and forming equipment (melting and forming processes).

[0348] Subsequently, the molten glass, which will be in the form of a plate at 800°C, is cooled to room temperature at an average cooling rate of 800°C / minute through a slow cooling device, resulting in a glass blank plate of 37cm×47cm and 1.1mm thickness (cooling process).

[0349] Next, the temperature was increased to Tmax℃ in Table 10 at a rate of 10℃ / min, and held at Tmax℃ for the time specified in the "Holding Time (minutes)" section of Table 10. The temperature was then decreased in an electric furnace to (Tg-300)℃ at the average cooling rate specified in Table 10. Otherwise, a glass plate was obtained in the same manner as in Example 1. Examples 32 to 34 are examples.

[0350] It should be noted that when the average cooling rate of the central part of the glass blank is set to VC (°C / min) and the average cooling rate of the ends is set to VE (°C / min), the furnace temperature is adjusted such that the ratio expressed by VC / VE is 1.1 or less. Here, the ends of the glass blank refer to the position 10cm from the end of the glass blank.

[0351] The relative permittivity and dielectric loss tangent of the obtained glass plate were measured under the same conditions as in Example 1. Measurements were taken at four locations near the approximate center and corners of the plate, and their maximum and minimum values ​​were recorded. The results are shown in Table 10.

[0352] In addition, the minimum value of Δtanδ and the maximum value of εr100 / εrA are shown in Table 9. Furthermore, the differences in tanδA and εrA at the two locations with the largest differences in tanδA and εrA at the two locations with the largest differences in εrA among the four locations near the approximate center and corners of the plate are shown in Table 10.

[0353] [Table 10]

[0354] Table 10

[0355]

[0356] The invention has been described in detail with reference to specific methods, but various changes and modifications can be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. It should be noted that this application is based on, in its entirety, Japanese patent applications filed April 12, 2019 (Japanese Patent Application No. 2019-76423), June 28, 2019 (Japanese Patent Application No. 2019-120828), and November 27, 2019 (Japanese Patent Application No. 2019-214690). Furthermore, all references cited herein are incorporated herein by reference in their entirety.

Claims

1. A glass plate, obtained by melting glass raw materials and cooling the molten glass, which is then formed into a plate shape, to a temperature below (Tg-300) °C relative to the glass transition temperature Tg (°C). Expressed as a molar percentage based on oxides, it contains: SiO2 57-70%, Al2O3 5-15%, B2O3 15-24%, Al2O3 + B2O3 20-40% 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 0–5%, where R = alkali metal. The average cooling rate from (Tg+50)℃ to (Tg-100)℃ exceeds 10℃ / minute. The relative permittivity at 10 GHz is εrA. When the relative permittivity at 10 GHz is set to εr100, after the glass plate is heated to (Tg+50)℃ and then cooled to (Tg-150)℃ at a rate of 100℃ / min, the following condition is satisfied: 0.95 ≤ (εr100 / εrA) ≤ 1.

05. If the dielectric loss tangent at 10 GHz is defined as tanδA, and the dielectric loss tangent at 10 GHz is defined as tanδ100 when the glass plate is heated to (Tg+50)℃ and then cooled to (Tg-150)℃ at a rate of 100℃ / min, then (tanδ100-tanδA)≥0.0004. The manufacturing method of the glass plate includes the following steps in sequence: The melting and forming process involves melting the glass raw material and then forming the molten glass into a plate shape. The cooling process involves cooling the molten glass, which has been formed into a plate shape, to a temperature below (Tg-300) °C relative to the glass transition temperature Tg (°C) to obtain a glass preform. The heat treatment process involves heating the obtained glass blank from a temperature below (Tg-300)℃ to a range of (Tg-100)℃ to (Tg+50)℃ without exceeding (Tg+50)℃, and then cooling it again to below (Tg-300)℃. Perform the heat treatment process once or twice or more. The first heat treatment process involves the glass blank being heated to a temperature exceeding (Tg-300)℃, then subjected to a maximum temperature Temax℃ within the range of (Tg-100)℃ to (Tg+50)℃, until it falls below (Tg-300)℃ again. In the entire heat treatment process, the total time during which the temperature of the glass blank is in the range of (Tg-100)℃~(Tg+50)℃ is greater than or equal to K using the highest temperature Tmax℃ of the glass blank in the entire heat treatment process, expressed by the following formula (1), where K is in minutes. In each of the aforementioned heat treatment processes, if the time from the last moment of cooling down from the highest temperature Temax℃ until the moment when (Tg-110)℃ is finally passed is t1, then the following equation (2) is satisfied, where the unit of t1 is minutes. If the maximum temperature Temax℃ is reached only once, the final moment of cooling from that temperature refers to the moment when cooling began at that temperature. If the maximum temperature Temax℃ is reached two or more times, the final moment of cooling from that temperature refers to the moment of the last instance of cooling from that temperature. Furthermore, if the maximum temperature Temax℃ is maintained for a certain period of time, the final moment of cooling from that temperature refers to the moment when that maintenance period ends. K = [{(Tg + 50) - Tmax} / 10] + 15 Equation (1) {Temax-(Tg-110)} / t1≤10 Equation (2).

2. The glass plate according to claim 1, wherein, The area of ​​the main surface of the glass plate is 350 cm². 2 above.

3. The glass plate according to claim 1 or 2, wherein, The dielectric loss tangent at 10GHz is below 0.

009.

4. The glass plate according to claim 1 or 2, wherein, The relative permittivity at 10 GHz is below 6.

8.

5. The glass plate according to claim 1 or 2, wherein, The difference in dielectric loss tangent at any two locations more than 40 mm apart at 10 GHz is less than 0.0005.

6. The glass plate according to claim 1 or 2, wherein, The difference in relative permittivity at 10 GHz between any two points more than 40 mm apart is less than 0.

05.

7. The glass plate according to claim 1 or 2, which is used as a substrate for a high-frequency device that processes high-frequency signals above 3.0 GHz.

8. The glass plate according to claim 1 or 2, which is used as a window material.

9. A method for manufacturing a glass plate, comprising the steps described in claim 1 or 2, wherein the steps are as follows: The melting and forming process involves melting the glass raw material and then forming the molten glass into a plate shape. The cooling process involves cooling the molten glass, which has been formed into a plate shape, to a temperature below (Tg-300) °C relative to the glass transition temperature Tg (°C) to obtain a glass preform. The heat treatment process involves heating the obtained glass blank from a temperature below (Tg-300)℃ to a range of (Tg-100)℃ to (Tg+50)℃ without exceeding (Tg+50)℃, and then cooling it again to below (Tg-300)℃. Perform the heat treatment process once or twice or more. The first heat treatment process involves the glass blank being heated to a temperature exceeding (Tg-300)℃, then subjected to a maximum temperature Temax℃ within the range of (Tg-100)℃ to (Tg+50)℃, until it falls below (Tg-300)℃ again. In the entire heat treatment process, the total time during which the temperature of the glass blank is in the range of (Tg-100)℃~(Tg+50)℃ is greater than or equal to K using the highest temperature Tmax℃ of the glass blank in the entire heat treatment process, expressed by the following formula (1), where K is in minutes. In each of the aforementioned heat treatment processes, if the time from the last moment of cooling down from the highest temperature Temax℃ until the moment when (Tg-110)℃ is finally passed is t1, then the following equation (2) is satisfied, where the unit of t1 is minutes. If the maximum temperature Temax℃ is reached only once, the final moment of cooling from that temperature refers to the moment when cooling began at that temperature. If the maximum temperature Temax℃ is reached two or more times, the final moment of cooling from that temperature refers to the moment of the last instance of cooling from that temperature. Furthermore, if the maximum temperature Temax℃ is maintained for a certain period of time, the final moment of cooling from that temperature refers to the moment when that maintenance period ends. K = [{(Tg + 50) - Tmax} / 10] + 15 Equation (1) {Temax-(Tg-110)} / t1≤10 Equation (2).

10. The method for manufacturing a glass plate according to claim 9, wherein, In each of the heat treatment processes, after the temperature of the glass blank drops from the highest temperature Temax℃ and first falls below (Tg-110)℃, it will not exceed (Tg-110)℃ again.

11. The method for manufacturing a glass plate according to claim 9 or 10, wherein, In each of the aforementioned heat treatment processes, any two moments from the last moment of cooling down from the highest temperature Temax℃ until the moment when (Tg-110)℃ is finally reached are designated as t2 and t3, and t2<t3. The units of t2 and t3 are minutes. The difference between time t2 and time t3 is more than 1 minute. When the temperature of the glass blank at t2 is set to Te2 and the temperature of the glass blank at t3 is set to Te3, the following equation (3) is satisfied. (Te2-Te3) / (t3-t2)≤10 Equation (3).

12. The method for manufacturing a glass plate according to claim 9 or 10, wherein, The average cooling rate in the cooling process is 10 to 1000°C / minute.

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