Glass sheets, laminated glass, architectural window glass, and vehicle window glass

Abstract

The present invention pertains to a glass plate which contains or does not contain predetermined amounts of SiO2, Al2O3, B2O3, P2O5, MgO, CaO, SrO, BaO, ZnO, Li2O, Na2O, K2O, R2O, Fe2O3, and RO, satisfies B2O3-Al2O3>0.0% and 0.30<Al2O3 / RO<0.50, has a temperature T12, at which the glass viscosity is 1012 dPa∙s, of at most 730ºC, and has an average thermal expansion coefficient of at least 40×10-7 / K at 50-350ºC.

Description

[Technical Field]

[0001] This invention relates to glass plates, laminated glass, architectural window glass, and vehicle window glass. [Background technology]

[0002] In recent years, the construction of communication infrastructure using 4G LTE and 5G, as well as communication using millimeter-wave radar of 30GHz or higher, including for autonomous driving, are expected to lead to the widespread adoption of high-speed and high-capacity data communication in the future.

[0003] However, when installing such millimeter-wave radar inside vehicles or buildings and attempting to transmit millimeter-wave radio waves through window glass, conventional vehicle and building window glass is unsuitable as next-generation glass because it has low millimeter-wave transmittance. This is due to the poor dielectric properties of soda-lime glass, which is currently used in many vehicle and building window panes.

[0004] On the other hand, examples of glass with high radio wave transparency for 5G communication using millimeter waves include glass compositions such as alkali-free glass and slightly alkali glass. For example, Patent Document 1 discloses an alkali-free glass composition used in the manufacture of liquid crystal display devices. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 7-300336 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when manufacturing glass sheets that require a bending process, such as curved automotive windshields or aesthetically pleasing curved architectural window glass, using glass compositions such as alkali-free glass or slightly alkali glass, a higher temperature was required for molding compared to soda-lime glass. The glass composition disclosed in Patent Document 1 is also intended for use in the manufacture of liquid crystal display devices, and bending of a glass substrate made of this glass composition is not anticipated. Therefore, when bending such a glass substrate, high-temperature molding was required.

[0007] Furthermore, when considering the use of glass compositions such as alkali-free glass or slightly alkali glass, which have high radio wave transmittance for 5G communications including millimeter-wave radar, there was a problem in that it was difficult to incorporate air-cooling enhancement.

[0008] In view of the above problems, the present invention provides a glass plate, laminated glass, and a window glass for buildings or vehicles using the glass plate or laminated glass, which have high millimeter-wave transmittance and can be bent and formed at a low temperature. [Means for solving the problem]

[0009] The glass plate according to an embodiment of the present invention is expressed in mole percentage based on oxide, 50% ≤ SiO2 ≤ 80% 5.0% ≤ Al2O3 ≤ 10% 5.0% <B2O3≦15% 0.0% ≤ P2O5 ≤ 10% 0.0% ≤ MgO ≤ 10% 0.0% ≤ CaO ≤ 10% 0.0% ≤ SrO ≤ 10% 0.0% ≤ BaO ≤ 10% 0.0% ≤ ZnO ≤ 5.0% 0.0% ≤ Li2O ≤ 5.0% 0.0% ≤ Na2O ≤ 5.0% 0.0% ≤ K2O ≤ 5.0% 0.0% ≤ R2O ≤ 5.0% Fe2O3 ≥ 0.04% 15% ≤ RO ≤ 30% B2O3-Al2O3>0.0% 0.30 <Al2O3 / RO<0.50 It contains (R2O represents the total amount of Li2O, Na2O, and K2O, and RO represents the total amount of MgO, CaO, SrO, and BaO), Glass viscosity is 10 12 Temperature T at which dPa·s occurs 12 The temperature is below 730℃. The average coefficient of thermal expansion between 50°C and 350°C is 40 × 10⁻⁶. -7 It is greater than or equal to / K.

[0010] Furthermore, in a glass plate according to one aspect of the present invention, the temperature T 12 However, temperatures below 720°C are also acceptable.

[0011] Furthermore, in a glass plate according to one aspect of the present invention, the relative permittivity (ε) at a frequency of 10 GHz is r ) may be 6.5 or less.

[0012] Furthermore, in a glass plate according to one aspect of the present invention, the dielectric loss tangent (tanδ) at a frequency of 10 GHz may be 0.0090 or less.

[0013] Furthermore, in a glass plate according to one aspect of the present invention, when the thickness is converted to 2.00 mm, Using a D65 light source, the visible light transmittance Tv, as defined in ISO-9050:2003, may be 75% or higher.

[0014] Furthermore, in a glass plate according to one aspect of the present invention, when the thickness is converted to 2.00 mm, the total solar radiation transmittance Tts, as defined in ISO-13837:2008 convention A and measured at a wind speed of 4 m / s, may be 88% or less.

[0015] Furthermore, in a glass plate according to one aspect of the present invention, the total solar radiation transmittance Tts may be 80% or less.

[0016] Furthermore, in a glass plate according to one aspect of the present invention, expressed as a mole percentage based on oxide, 55% ≤ SiO2 ≤ 70% 6.0% ≤ Al2O3 ≤ 8.0% 7.0% ≤ B2O3 ≤ 12% 0.0% ≤ P2O5 ≤ 5.0% 2.0% ≤ MgO ≤ 7.0% 2.0% ≤ CaO ≤ 7.0% 2.0% ≤ SrO ≤ 7.0% 2.0% ≤ BaO ≤ 7.0% 0.0% ≤ ZnO ≤ 3.0% 0.04% ≤ Fe2O3 ≤ 0.50% 16% ≤ RO ≤ 25% 0.0% ≤ R²O ≤ 3.0% It may contain.

[0017] Furthermore, in one embodiment of the present invention, a glass plate may be made of air-cooled tempered glass.

[0018] The laminated glass according to an embodiment of the present invention comprises a first glass plate, a second glass plate, and an interlayer sandwiched between the first glass plate and the second glass plate, wherein at least one of the first glass plate and the second glass plate is the glass plate described above.

[0019] Furthermore, in a laminated glass according to one aspect of the present invention, the total thickness of the first glass plate, the second glass plate, and the interlayer may be 5.00 mm or less, and the visible light transmittance Tv, as defined in ISO-9050:2003 using a D65 light source, may be 70% or more.

[0020] Furthermore, in a laminated glass according to one aspect of the present invention, the total thickness of the first glass plate, the second glass plate, and the interlayer may be 5.00 mm or less, and the total solar radiation transmittance Tts, as defined in ISO-13837:2008 convention A and measured at a wind speed of 4 m / s, may be 70% or less.

[0021] Furthermore, in a laminated glass according to one aspect of the present invention, the total thickness of the first glass plate, the second glass plate, and the interlayer film may be 5.00 mm or less, and the maximum value of the radio wave transmission loss S21 when a TM wave with a frequency of 75 GHz to 80 GHz is incident on the first glass plate at an incident angle of 60° may be -4.0 dB or more.

[0022] Furthermore, in a laminated glass according to one aspect of the present invention, the total thickness of the first glass plate, the second glass plate, and the interlayer film may be 5.00 mm or less, and the maximum value of the radio wave transmission loss S21 when a TM wave with a frequency of 75 GHz to 80 GHz is incident on the first glass plate at an incident angle of 45° may be -4.0 dB or more.

[0023] Furthermore, in a laminated glass according to one aspect of the present invention, the total thickness of the first glass plate, the second glass plate, and the interlayer may be 5.00 mm or less, and the maximum value of the radio wave transmission loss S21 when a TM wave with a frequency of 75 GHz to 80 GHz is incident on the first glass plate at an incident angle of 20° may be -4.0 dB or more.

[0024] An architectural window glass according to an embodiment of the present invention has the above-mentioned glass plate.

[0025] A vehicle window glass according to an embodiment of the present invention has the above-mentioned glass plate.

[0026] Another embodiment of the present invention provides a vehicle window glass having the laminated glass described above. [Effects of the Invention]

[0027] According to the present invention, it is possible to provide glass plates, laminated glass, and architectural window glass or vehicle window glass using the glass plate or laminated glass, which have high millimeter-wave transmittance and can be bent and formed at a low temperature. [Brief explanation of the drawing]

[0028] [Figure 1]Figure 1 is a cross-sectional view of an example of laminated glass according to an embodiment of the present invention. [Figure 2] Figure 2 is a conceptual diagram showing how the laminated glass according to an embodiment of the present invention is used as window glass for a vehicle. [Figure 3] Figure 3 is an enlarged view of section S in Figure 2. [Figure 4] Figure 4 is a cross-sectional view along the YY line in Figure 3. [Modes for carrying out the invention]

[0029] Embodiments of the present invention will be described in detail below. In the following drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic representations for the purpose of clearly illustrating the present invention and do not necessarily accurately represent the size or scale of the actual product.

[0030] In this specification, evaluations such as "high / low millimeter wave radio wave transparency" refer to the radio wave transparency including quasi-millimeter waves and millimeter waves unless otherwise specified, and for example, refer to the radio wave transparency of glass to radio waves with frequencies from 10 GHz to 90 GHz.

[0031] In this specification, "substantially free" of a certain component in glass means that it is not contained except for unavoidable impurities, and that the component is not actively added. Specifically, this means that the content of each of these components in the glass is approximately 100 ppm or less, expressed in molar ppm based on oxides.

[0032] [glass plate] The glass plate according to the embodiment of the present invention is expressed in mole percentage based on oxide, 50% ≤ SiO2 ≤ 80% 5.0% ≤ Al2O3 ≤ 10% 5.0% <B2O3≦15% 0.0% ≤ P2O5 ≤ 10% 0.0% ≤ MgO ≤ 10% 0.0% ≤ CaO ≤ 10% 0.0% ≤ SrO ≤ 10% 0.0% ≤ BaO ≤ 10% 0.0% ≤ ZnO ≤ 5.0% 0.0% ≤ Li2O ≤ 5.0% 0.0% ≤ Na2O ≤ 5.0% 0.0% ≤ K2O ≤ 5.0% 0.0% ≤ R2O ≤ 5.0% Fe2O3 ≥ 0.04% 15% ≤ RO ≤ 30% B2O3-Al2O3>0.0% 0.30 <Al2O3 / RO<0.50 It contains (R2O represents the total amount of Li2O, Na2O, and K2O, and RO represents the total amount of MgO, CaO, SrO, and BaO), Glass viscosity is 10 12 Temperature T at which dPa·s occurs 12 The temperature is below 730℃. The average coefficient of thermal expansion between 50°C and 350°C is 40 × 10⁻⁶. -7 It is characterized by being greater than or equal to / K.

[0033] The following describes the composition range of each component in the glass plate of this embodiment. Unless otherwise specified, the composition range of each component is expressed as a mole percentage based on the oxide.

[0034] SiO2 is an essential component of the glass plate in this embodiment. The SiO2 content is 50% or more and 80% or less. SiO2 contributes to improving the Young's modulus, making it easier to secure the strength required for applications such as vehicles and buildings. If the SiO2 content is too low, it becomes difficult to ensure weather resistance, and the average coefficient of thermal expansion becomes too high, which may cause the glass plate to crack due to thermal stress. On the other hand, if the SiO2 content is too high, the viscosity during glass melting increases, which may make glass manufacturing difficult.

[0035] The SiO2 content in the glass plate of this embodiment is preferably 55% or more, more preferably 58% or more, even more preferably 59% or more, and particularly preferably 60% or more.

[0036] Furthermore, the SiO2 content in the glass plate of this embodiment is preferably 70% or less, more preferably 68% or less, even more preferably 66% or less, and particularly preferably 65% ​​or less.

[0037] Al2O3 is an essential component of the glass plate in this embodiment. The Al2O3 content is between 5.0% and 10%. If the Al2O3 content is too low, it becomes difficult to ensure weather resistance, and the average coefficient of thermal expansion becomes too large, which may cause the glass plate to crack due to thermal stress.

[0038] On the other hand, too much Al2O3 can increase the viscosity during glass melting, potentially making glass manufacturing difficult. When Al2O3 is included, the Al2O3 content is preferably 5.5% or more, more preferably 6.0% or more, and even more preferably 6.5% or more, in order to suppress phase separation of the glass and improve weather resistance.

[0039] The Al2O3 content is preferably 9.0% or less, more preferably 8.0% or less, and even more preferably 7.5% or less, from the viewpoint of keeping T2 low and facilitating glass manufacturing, and from the viewpoint of increasing millimeter-wave radio wave transmittance.

[0040] B2O3 is an essential component of the glass plate in this embodiment. The B2O3 content is greater than 5.0% and less than or equal to 15%. B2O3 is included to improve glass strength and millimeter-wave radio wave transmission, as well as to improve solubility.

[0041] The B2O3 content in the glass plate of this embodiment is preferably 7.0% or more, more preferably 8.0% or more, and even more preferably 9.0% or more.

[0042] On the other hand, if the content of B2O3 is too high, alkali elements are likely to volatilize during melting and forming, which may reduce the glass quality and may also reduce the acid resistance and alkali resistance. Therefore, the content of B2O3 is preferably 14% or less, more preferably 13% or less, still more preferably 12% or less, and particularly preferably 11% or less.

[0043] To increase the radio wave transmittance of millimeter waves, the total of SiO2 + Al2O3 + B2O3 in the glass plate of the present embodiment, that is, the total of the SiO2 content, the Al2O3 content, and the B2O3 content, is preferably 70% or more and 85% or less.

[0044] Furthermore, considering further making it easier to manufacture the glass by keeping the temperatures T2 and T4 of the glass plate of the present embodiment low, SiO2 + Al2O3 + B2O3 is preferably 83% or less, and more preferably 82% or less.

[0045] However, if SiO2 + Al2O3 + B2O3 is too low, the weather resistance may decrease, and the relative permittivity (ε r ) and the dielectric loss tangent (tanδ) may become too large. Therefore, SiO2 + Al2O3 + B2O3 of the glass plate of the present embodiment is preferably 75% or more, and more preferably 76% or more.

[0046] P2O5 is an optional component of the glass plate of the present embodiment. The content of P2O5 is 0.0% or more and 10% or less. P2O5 has a function of lowering the viscosity of the glass. When P2O5 is contained in the glass plate of the present embodiment, it is preferably 0.2% or more, more preferably 0.5% or more, still more preferably 0.8% or more, and particularly preferably 1.0% or more.

[0047] On the other hand, in the production of the glass plate of the present embodiment by the float method, P2O5 is likely to cause defects in the glass in the float bath. Therefore, the content of P2O5 in the glass plate of the present embodiment is preferably 5.0% or less, more preferably 4.0% or less, still more preferably 3.0% or less, and particularly preferably 2.0% or less.

[0048] MgO is an optional component of the glass plate in this embodiment. The MgO content is between 0.0% and 10%. MgO is a component that promotes the dissolution of the glass raw material and improves weather resistance and Young's modulus.

[0049] If MgO is included, it is preferably 2.0% or more, more preferably 2.5% or more, even more preferably 3.0% or more, particularly preferably 3.5% or more, and most preferably 4.0% or more.

[0050] Furthermore, if the MgO content is 10% or less, devitrification becomes less likely, and the relative permittivity (ε) r ) and the increase in dielectric loss tangent (tanδ) can be suppressed. The MgO content is preferably 7.0% or less, more preferably 6.5% or less, even more preferably 6.0% or less, particularly preferably 5.5% or less, and most preferably 5.0% or less.

[0051] CaO is an optional component of the glass plate in this embodiment and may be included in a certain amount to improve the solubility of the glass raw material. The CaO content is 0.0% or more and 10% or less. When CaO is included, 2.0% or more is preferred, 2.5% or more is more preferred, 3.0% or more is even more preferred, 3.5% or more is particularly preferred, and 4.0% or more is most preferred. This improves the solubility and moldability (decrease in T2 and T4) of the glass raw material.

[0052] Furthermore, by keeping the CaO content below 10%, an increase in glass density is avoided, maintaining low brittleness and strength. This prevents the glass from becoming brittle, and also maintains the relative permittivity (ε) of the glass. r To prevent an increase in the dielectric loss tangent (tanδ), the CaO content is preferably 7.0% or less, more preferably 6.5% or less, even more preferably 6.0% or less, particularly preferably 5.5% or less, and most preferably 5.0% or less.

[0053] SrO is an optional component of the glass plate in this embodiment and may be included in a certain amount to improve the solubility of the glass raw material. The SrO content is 0.0% or more and 10% or less. When SrO is included, 2.0% or more is preferred, 2.5% or more is more preferred, 3.0% or more is even more preferred, 3.5% or more is particularly preferred, and 4.0% or more is most preferred. This improves the solubility and moldability (decrease in T2 and T4) of the glass raw material.

[0054] Furthermore, by keeping the SrO content below 10%, an increase in glass density is avoided, maintaining low brittleness and strength. This prevents the glass from becoming brittle, and also maintains the relative permittivity (ε) of the glass. r To prevent an increase in the dielectric loss tangent (tanδ), the SrO content is preferably 7.0% or less. Furthermore, the SrO content is more preferably 6.5% or less, even more preferably 6.0% or less, particularly preferably 5.5% or less, and most preferably 5.0% or less.

[0055] BaO is an optional component of the glass plate in this embodiment and may be included in a certain amount to improve the solubility of the glass raw material. The BaO content is 0.0% or more and 10% or less. When BaO is included, 2.0% or more is preferred, 2.5% or more is more preferred, 3.0% or more is even more preferred, 3.5% or more is particularly preferred, and 4.0% or more is most preferred. This improves the solubility and moldability (decrease in T2 and T4) of the glass raw material.

[0056] Furthermore, by keeping the BaO content below 10%, an increase in glass density is avoided, maintaining low brittleness and strength. This prevents the glass from becoming brittle, and also maintains the relative permittivity (ε) of the glass. r To prevent an increase in the dielectric loss tangent (tanδ), the BaO content is preferably 7.0% or less. More preferably, the BaO content is 6.5% or less, even more preferably 6.0% or less, particularly preferably 5.5% or less, and most preferably substantially absent.

[0057] ZnO is an optional component of the glass plate in this embodiment and may be included in a certain amount to reduce the viscosity of the glass. The ZnO content is 0.0% or more and 5.0% or less. If ZnO is included, 0.10% or more is preferred, 0.50% or more is more preferred, and 1.0% or more is even more preferred.

[0058] Furthermore, by reducing the ZnO content to 5.0% or less, the dielectric constant (ε r The increase in relative permittivity (ε) and dielectric loss tangent (tanδ) can be suppressed. r To suppress increases in ) and dielectric loss tangent (tanδ), the ZnO content is preferably 3.0% or less. Furthermore, the ZnO content is more preferably 2.5% or less, and even more preferably 2.0% or less.

[0059] Li2O is an optional component of the glass plate in this embodiment. The Li2O content is between 0.0% and 5.0%. Li2O is a component that improves the solubility of glass and also contributes to improving the strength of glass by making it easier to increase Young's modulus.

[0060] The inclusion of Li2O reduces the viscosity of the glass, thereby improving the moldability of vehicle window glass, particularly windshields. When Li2O is included in the glass plate of this embodiment, 0.10% or more is preferred, 0.40% or more is more preferred, 0.60% or more is even more preferred, 0.80% or more is particularly preferred, and 1.0% or more is most preferred.

[0061] On the other hand, if the Li2O content is too high, devitrification or phase separation may occur during glass manufacturing, potentially making production difficult. Furthermore, a high Li2O content can increase raw material costs and the dielectric constant (ε) r This may cause an increase in the dielectric loss tangent (tanδ). Therefore, the Li2O content is preferably 4.0% or less, more preferably 3.5% or less, even more preferably 3.0% or less, particularly preferably 2.5% or less, and most preferably 2.0% or less.

[0062] Na2O is an optional component of the glass plate in this embodiment. The Na2O content is between 0.0% and 5.0%. By including Na2O, the viscosity of the glass is reduced, thereby improving the moldability of vehicle window glass, especially windshields.

[0063] If Na2O is included, it is preferably 0.10% or more, more preferably 0.40% or more, even more preferably 0.60% or more, particularly preferably 0.80% or more, and most preferably 1.0% or more.

[0064] On the other hand, if there is too much Na2O, the relative permittivity (ε r This causes an increase in the dielectric loss tangent (tanδ). Therefore, the Na2O content is preferably 4.0% or less, more preferably 3.5% or less, even more preferably 3.0% or less, particularly preferably 2.5% or less, and most preferably 2.0% or less.

[0065] K2O is an optional component of the glass plate in this embodiment. The K2O content is 0.0% or more and 5.0% or less. By including K2O, the viscosity of the glass is reduced, which improves the moldability of vehicle window glass, especially windshields. When K2O is included, 0.10% or more is preferred, 0.40% or more is more preferred, 0.60% or more is even more preferred, 0.80% or more is particularly preferred, and 1.0% or more is most preferred.

[0066] On the other hand, if the K2O content is too high, the relative permittivity (ε r This causes an increase in the dielectric loss tangent (tanδ). Therefore, the K2O content is preferably 4.0% or less, more preferably 3.5% or less, even more preferably 3.0% or less, particularly preferably 2.5% or less, and most preferably 2.0% or less.

[0067] R2O refers to the total content of Li2O, Na2O, and K2O. The R2O content is between 0.0% and 5.0%. If the R2O content in the glass plate of this embodiment is 5.0% or less, the moldability of vehicle window glass, especially windshields, is improved while maintaining weather resistance and millimeter-wave radio wave transmission. The R2O content of the glass plate of this embodiment is preferably 4.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, particularly preferably 1.5% or less, and most preferably 1.0% or less.

[0068] Furthermore, from the viewpoint of lowering temperatures T2 and T4 during manufacturing, or to facilitate heating by direct current application to the glass melt, it is preferable to include a small amount of R2O. In the glass plate of this embodiment, the R2O content is preferably 0.10% or more, more preferably 0.40% or more, even more preferably 0.60% or more, and particularly preferably 0.80% or more.

[0069] Fe2O3 is an essential component of the glass plate in this embodiment and is included to provide heat-shielding properties. The Fe2O3 content is 0.04% or more. The Fe2O3 content referred to here is the total amount of iron, including FeO, which is an oxide of divalent iron, and Fe2O3, which is an oxide of trivalent iron.

[0070] If the Fe2O3 content is less than 0.04%, the glass may not be suitable for applications requiring heat shielding, and it may become necessary to use expensive raw materials with low iron content for the manufacture of glass sheets. Furthermore, if the Fe2O3 content is less than 0.04%, excessive heat radiation may reach the bottom of the melting furnace during glass melting, potentially putting a load on the furnace.

[0071] The Fe2O3 content in the glass plate of this embodiment is preferably 0.10% or more, more preferably 0.13% or more, even more preferably 0.15% or more, and particularly preferably 0.17% or more.

[0072] On the other hand, if the Fe2O3 content is too high, heat transfer by radiation during manufacturing may be hindered, making it difficult to melt the raw material. Furthermore, if the Fe2O3 content is too high, a decrease in visible light transmittance may occur, making it unsuitable for vehicle window glass and the like. The Fe2O3 content is preferably 0.50% or less, more preferably 0.40% or less, even more preferably 0.30% or less, and particularly preferably 0.25% or less.

[0073] Furthermore, the amount of iron ions contained in the above Fe2O3 is 0.50 ≤ [Fe 2+ ] / ([Fe 2+ ]+[Fe 3+ It is preferable that the condition ]) ≤ 0.90 is satisfied. This makes it possible to achieve transmittance in the visible range and the near-infrared range that are suitable for vehicle glass.

[0074] Here, [Fe 2+ ], and [Fe 3+ ] refers to the Fe contained in the glass plate of this embodiment, respectively. 2+ , and Fe 3+ It means the amount of [Fe 2+ ] / ([Fe 2+ ]+[Fe 3+ ])" refers to the Fe in the glass plate of this embodiment. 2+ and Fe 3+ Fe relative to the total content 2+ This refers to the percentage of the content.

[0075] [Fe 2+ ] / ([Fe 2+ ]+[Fe 3+ ]) can be found using the following method.

[0076] After decomposing the crushed glass at room temperature with a mixed acid of hydrofluoric acid and hydrochloric acid, a certain amount of the decomposition solution is taken into a plastic container, and hydroxylammonium chloride solution is added, and the Fe in the sample solution 3+ Fe 2+ Reduce to . Then, add 2,2'-dipyridyl solution and ammonium acetate buffer and Fe 2+The color is developed. The color developing solution is diluted to a constant volume with deionized water, and the absorbance at a wavelength of 522 nm is measured using a spectrophotometer. Then the concentration is calculated from the calibration curve prepared using the standard solution and Fe 2+ Determine the quantity. Fe in the sample solution 3+ Fe 2+ Because it is reduced to this Fe 2+ The amount is "[Fe 2+ ]+[Fe 3+ ] means ".

[0077] Next, the crushed glass was decomposed at room temperature with a mixed acid of hydrofluoric acid and hydrochloric acid. Then, a certain amount of the decomposition solution was taken into a plastic container, and 2,2'-dipyridyl solution and ammonium acetate buffer were quickly added to Fe 2+ Only the color develops. The color developing solution is diluted with deionized water to a constant volume, and the absorbance at a wavelength of 522 nm is measured using a spectrophotometer. Then the concentration is calculated from the calibration curve prepared using the standard solution and Fe 2+ Calculate the quantity. This Fe 2+ The amount is [Fe in the sample] 2+ It means ].

[0078] And the above-calculated [Fe 2+ ], and [Fe 2+ ]+[Fe 3+ ] to [Fe 2+ ] / ([Fe 2+ ]+[Fe 3+ Calculate ]).

[0079] RO represents the total content of MgO, CaO, SrO, and BaO. The RO content is between 15% and 30%. If the RO content of the glass plate in this embodiment is 30% or less, the relative permittivity (ε) is maintained while maintaining weather resistance. r ) and the increase in dielectric loss tangent (tanδ) can be suppressed. The RO content in the glass plate of this embodiment is preferably 25% or less, more preferably 24% or less, even more preferably 23% or less, even more preferably 22% or less, particularly preferably 21% or less, and most preferably 20% or less.

[0080] From the perspective of reducing the temperatures T2 and T4 during manufacturing, or from the perspective of improving the formability of vehicle window glass, particularly windshield, the content of RO in the glass plate of the present embodiment is preferably 16% or more, more preferably 17% or more, and particularly preferably 18% or more.

[0081] In the glass plate of the present embodiment, the value obtained by subtracting the content of Al2O3 from the content of B2O3 (B2O3 - Al2O3) is greater than 0.0%. That is, B2O3 - Al2O3 > 0.0%. Thereby, bending and forming processing at a low temperature becomes possible as described later. B2O3 - Al2O3 is preferably 1.0% or more, more preferably 2.0% or more, and even more preferably 3.0% or more.

[0082] In the glass plate of the present embodiment, the value obtained by dividing the content of Al2O3 by the content of RO excluding the content of RO (Al2O3 / RO) is greater than 0.30 and less than 0.50. That is, 0.30 < Al2O3 / RO < 0.50. Thereby, phase separation of the glass can be suppressed, preventing the glass from becoming cloudy and reducing the viscosity of the glass.

[0083] In the glass plate of the present embodiment, Al2O3 / RO is preferably 0.32 or more, more preferably 0.35 or more, and even more preferably 0.37 or more. Also, Al2O3 / RO is preferably 0.45 or less, more preferably 0.43 or less, and even more preferably 0.41 or less.

[0084] In the glass plate of the present embodiment, the temperature T at which the glass viscosity becomes 10 12 dPa·s 12 is 730°C or lower. T 12 being 730°C or lower enables bending and forming processing at a low temperature. T 12 As a method of making T 730°C or lower, for example, a method of making the content of Al2O3 10% or less, B2O3 - Al2O3 > 0.0%, and RO ≥ 15% can be mentioned.

[0085] In the glass plate of the present embodiment, T 12The temperature is preferably 720°C or lower, more preferably 715°C or lower, even more preferably 710°C or lower, particularly preferably 705°C or lower, and most preferably 700°C or lower.

[0086] Furthermore, in terms of the firing temperature of the black ceramic printed on the windshield, T 12 A temperature of 590°C or higher is preferred, 600°C or higher is more preferred, 610°C or higher is even more preferred, and 620°C or higher is particularly preferred.

[0087] The average thermal expansion coefficient of the glass plate in this embodiment at 50°C to 350°C is 40 × 10 -7 The average thermal expansion coefficient of the glass plate in this embodiment is 40 × 10 -7 A temperature of 1 / K or higher results in good bending properties at low temperatures. This can be achieved by keeping the Al2O3 content below 10%, B2O3-Al2O3 > 0.0%, and RO ≥ 15%.

[0088] The average thermal expansion coefficient of the glass plate in this embodiment at 50°C to 350°C is 45 × 10 -7 / K or higher is preferred, 47×10 -7 / K or higher is more preferable, 50×10 -7 / K or higher is even more preferable.

[0089] On the other hand, if the average coefficient of thermal expansion of the glass plate in this embodiment becomes too large, thermal stress due to the temperature distribution of the glass plate is likely to occur during the glass plate molding process, the slow cooling process, or the windshield molding process, which may cause thermal cracking of the glass plate.

[0090] Furthermore, in this embodiment, if the average coefficient of thermal expansion of the glass plate becomes too large, the difference in expansion between the glass plate and the support member will become large, which can cause distortion and potentially lead to the glass plate cracking.

[0091] Therefore, the average thermal expansion coefficient of the glass plate in this embodiment at 50°C to 350°C is 70 × 10 -7 / K or less is acceptable, and 68 × 10 -7Preferably less than / K, 65 × 10 -7 / K or less is more preferable, 60 × 10 -7 A value of / K or less is even more preferable.

[0092] In the glass plate of this embodiment, the presence of moisture in the glass absorbs light in the near-infrared region. Therefore, it is preferable that the glass plate of this embodiment contains a certain amount of moisture in order to enhance its heat-shielding properties.

[0093] The amount of water in glass can generally be expressed by a value called the β-OH value, which is 0.050 mm. -1 The above is preferable, 0.10 mm -1 The above is more preferable, 0.15 mm -1 The above is even more preferable.

[0094] β-OH can be obtained from the transmittance of the glass measured using FT-IR (Fourier Transform Infrared Spectrophotometer) by the following formula. β-OH=(1 / X)log 10 (T A / T B )[mm -1 ] X: Sample thickness [mm] T A :Reference wave number 4000cm -1 Transmittance [%] T B Hydroxyl group absorption wavenumber 3600 cm -1 Minimum transmittance in the vicinity [%]

[0095] On the other hand, if the water content in the glass is too high, problems may arise not only when transmitting and receiving millimeter-wave radio waves, but also when using infrared irradiation equipment (such as laser radar). Therefore, the β-OH value of the glass plate in this embodiment is 0.70 mm -1 The following is preferred: 0.60 mm -1 The following is more preferable: 0.50 mm -1 The following is even more preferable: 0.40 mm -1 The following are particularly preferable.

[0096] The density of the glass plate of this embodiment is 2.4 g / cm 3 or more and 2.9 g / cm 3 or less. Further, the Young's modulus of the glass plate of this embodiment may be 60 GPa or more and 85 GPa or less. If the glass plate of this embodiment satisfies these conditions, it can be suitably used as architectural window glass, vehicle window glass, or the like.

[0097] The glass plate of this embodiment preferably contains a certain amount or more of SiO2 in order to ensure weather resistance. As a result, the density of the glass plate of this embodiment can be 2.4 g / cm 3 or more.

[0098] The density of the glass plate of this embodiment is preferably 2.5 g / cm 3 or more. When the density is 2.5 g / cm 3 or more, the sound insulation in the room and the vehicle interior is improved. Further, when the density of the glass plate of this embodiment is 2.9 g / cm 3 or less, it is less likely to become brittle and high sound insulation can be maintained. The density of the glass plate of this embodiment is preferably 2.8 g / cm 3 or less.

[0099] The glass plate of this embodiment has high rigidity due to an increase in Young's modulus and becomes more suitable for vehicle window glass and the like. The Young's modulus of the glass plate of this embodiment is preferably 70 GPa or more, more preferably 74 GPa or more, and even more preferably 76 GPa or more.

[0100] On the other hand, increasing Al2O3 or MgO to increase the Young's modulus increases the relative permittivity (ε r ) and the dielectric loss tangent (tanδ) of the glass. Therefore, the appropriate Young's modulus of the glass plate of this embodiment is 84 GPa or less, more preferably 82 GPa or less, and even more preferably 80 GPa or less.

[0101] Further, in the glass plate of this embodiment, T2 is preferably 1700 °C or less. Further, in the glass plate of this embodiment, T4 is preferably 1300 °C or less, and T4 - T L is preferably -50 °C or more.

[0102] In addition, in this specification, T2 represents the temperature at which the glass viscosity becomes 10 2 dPa·s, and T4 represents the temperature at which the glass viscosity becomes 10 4 dPa·s, and T L represents the liquidus temperature of the glass.

[0103] When T2 or T4 of the glass plate of this embodiment becomes higher than these predetermined temperatures, it becomes difficult to manufacture a large glass plate by the float method, the roll-out method, the down-draw method, or the like.

[0104] In the glass plate of this embodiment, T2 is preferably 1640°C or lower, more preferably 1600°C or lower, and even more preferably 1550°C or lower. In the glass plate of this embodiment, T4 is more preferably 1270°C or lower, even more preferably 1250°C or lower, and particularly preferably 1200°C or lower.

[0105] The lower limits of T2 and T4 of the glass plate of this embodiment are not particularly limited, but in order to maintain weather resistance and the density of the glass, typically T2 is 1300°C or higher and T4 is 900°C or higher. For the glass plate of this embodiment, T2 is preferably 1350°C or higher, more preferably 1400°C or higher. For the glass plate of this embodiment, T4 is preferably 1000°C or higher, more preferably 1050°C or higher.

[0106] Furthermore, in order to enable production by the float method, T4 - T of the glass plate of this embodiment L is preferably -50°C or higher. If this difference is less than -50°C, devitrification occurs in the glass during glass forming, and problems such as a decrease in the mechanical properties of the glass and a decrease in transparency may occur, and there is a risk that good-quality glass cannot be obtained. T4 - T of the glass plate of this embodiment L is more preferably 0°C or higher, and even more preferably +20°C or higher.

[0107] Also, for the glass plate of this embodiment, T g is preferably 550°C or higher and 700°C or lower. In addition, in this specification, Tg This represents the glass transition point of glass. g If the temperature is within this specified range, the glass can be bent under normal manufacturing conditions.

[0108] T of the glass plate in this embodiment g If the temperature is lower than 550°C, there will be no problems with moldability, but the alkali content or alkaline earth content will become too high, which can lead to problems such as reduced millimeter-wave radio wave transmission, excessive thermal expansion of the glass, and decreased weather resistance. Also, the T of the glass plate in this embodiment g If the temperature is lower than 550°C, the glass may devitrify and become impossible to mold within the molding temperature range.

[0109] T of the glass plate in this embodiment g A temperature of 570°C or higher is more preferable, 580°C or higher is even more preferable, and 600°C or higher is particularly preferable. On the other hand, T g If the temperature is too high, a high temperature will be required during the glass bending process, making manufacturing difficult. g A temperature of 670°C or lower is more preferable, 660°C or lower is even more preferable, and 650°C or lower is particularly preferable.

[0110] Furthermore, by adjusting the composition of the glass plate in this embodiment, a low dielectric loss tangent (tanδ) can be achieved, resulting in reduced dielectric loss and high millimeter-wave radio wave transmittance. Similarly, by adjusting the composition of the glass plate in this embodiment, the relative permittivity (ε) can be reduced. r This can also be adjusted to suppress radio wave reflection at the interface with the interlayer, achieving high millimeter-wave radio wave transmittance.

[0111] Furthermore, the relative permittivity (ε) of the glass plate of this embodiment at a frequency of 10 GHz r ) is preferably 6.5 or less. Relative permittivity (ε) at a frequency of 10 GHz r If the ratio is 6.5 or less, the relative permittivity (ε) with respect to the interlayer is 6.5 or less. r The difference between the two is reduced, and the reflection of radio waves at the interface with the interlayer can be suppressed.

[0112] The relative permittivity (ε) of the glass plate of this embodiment at a frequency of 10 GHz r ) is more preferably 6.4 or less, even more preferably 6.3 or less, even more preferably 6.2 or less, particularly preferably 6.1 or less, and most preferably 6.0 or less.

[0113] Furthermore, the relative permittivity (ε) of the glass plate of this embodiment at a frequency of 10 GHz r There is no particular lower limit for ), but for example, it is 5.0 or higher.

[0114] Furthermore, the dielectric loss tangent (tanδ) of the glass plate in this embodiment at a frequency of 10 GHz is preferably 0.0090 or less. If the dielectric loss tangent (tanδ) at a frequency of 10 GHz is 0.0090 or less, the radio wave transmittance can be increased.

[0115] In this embodiment, the dielectric loss tangent (tanδ) of the glass plate at a frequency of 10 GHz is more preferably 0.0080 or less, even more preferably 0.0070 or less, particularly preferably 0.0065 or less, and most preferably 0.0060 or less.

[0116] Furthermore, the lower limit of the dielectric loss tangent (tanδ) of the glass plate in this embodiment at a frequency of 10 GHz is not particularly limited, but for example, it is 0.0030 or higher.

[0117] The relative permittivity (ε) of the glass plate of this embodiment at a frequency of 10 GHz r If the dielectric loss tangent (tanδ) and the dielectric loss tangent (10 GHz to 90 GHz) meet the above ranges, high millimeter-wave radio wave transmission can be achieved even at frequencies of 10 GHz to 90 GHz.

[0118] The relative permittivity (ε) of the glass plate of this embodiment at a frequency of 10 GHz r The dielectric constant (%) and dielectric loss tangent (tanδ) can be measured, for example, by the split-post dielectric resonator method (SPDR method). For such measurements, a QWED 10 GHz nominal fundamental frequency type split-post dielectric resonator, a Keysight E8361C vector network analyzer, and Keysight 85071E option 300 dielectric constant calculation software can be used.

[0119] In this embodiment, the glass plate contains NiO, but if NiO is included, glass breakage may occur due to the formation of NiS, so the NiO content is preferably 0.010% or less. More preferably, the NiO content in the glass plate of this embodiment is 0.0050% or less, and even more preferably, it contains substantially no NiO.

[0120] The glass plate of this embodiment may contain components other than SiO2, Al2O3, B2O3, P2O5, MgO, CaO, SrO, BaO, ZnO, Li2O, Na2O, K2O, and Fe2O3 (hereinafter also referred to as "other components"), and if they are included, the total content is preferably 5.0% or less. Examples of other components include ZrO2, Y2O3, Nd2O5, GaO2, GeO2, MnO2, CoO, Cr2O3, V2O5, Se, Au2O3, Ag2O, CuO, CdO, SO3, Cl, F, SnO2, Sb2O3, etc., and may be metal ions or oxides.

[0121] Other components may be included in amounts of 5.0% or less for various purposes (e.g., clarification and coloring). If the content of other components exceeds 5.0%, it may reduce the transmission rate of millimeter-wave radio waves. The content of other components is preferably 2.0% or less, more preferably 1.0% or less, even more preferably 0.50% or less, particularly preferably 0.30% or less, and most preferably 0.10% or less. In addition, to prevent environmental impact, the content of As2O3 and PbO is preferably less than 0.0010% each.

[0122] The glass plate of this embodiment may contain Cr2O3. Cr2O3 acts as an oxidizing agent to control the amount of FeO. When the glass plate of this embodiment contains Cr2O3, its content is preferably 0.0020% or more, and more preferably 0.0040% or more.

[0123] On the other hand, Cr2O3 has a coloration to visible light, which may reduce the visible light transmittance. When the glass plate of this embodiment contains Cr2O3, the amount is preferably 1.0% or less, more preferably 0.50% or less, even more preferably 0.30% or less, and particularly preferably 0.10% or less.

[0124] The glass plate of this embodiment may contain SnO2. SnO2 acts as a reducing agent to control the amount of FeO. When the glass plate of this embodiment contains SnO2, its content is preferably 0.010% or more, more preferably 0.040% or more, even more preferably 0.060% or more, and particularly preferably 0.080% or more.

[0125] On the other hand, in order to suppress defects caused by SnO2 during the manufacturing of glass plates, the SnO2 content in the glass plates of this embodiment is preferably 1.0% or less, more preferably 0.50% or less, even more preferably 0.30% or less, and particularly preferably 0.20% or less.

[0126] The glass plate of this embodiment preferably has sufficient visible light transmittance. When converted to a thickness of 2.00 mm, the visible light transmittance Tv, as defined in ISO-9050:2003 using a D65 light source, is preferably 75% or higher. Tv is preferably 77% or higher, and more preferably 80% or higher. Also, Tv is, for example, 90% or lower.

[0127] Furthermore, the glass plate of this embodiment preferably has high heat-shielding properties. When converted to a thickness of 2.00 mm, the total solar radiation transmittance Tts, as defined in ISO-13837:2008 convention A and measured at a wind speed of 4 m / s, is preferably 88% or less. Tts is preferably 80% or less, and more preferably 78% or less. Also, Tts is, for example, 70% or more.

[0128] Furthermore, the glass plate of this embodiment preferably has low ultraviolet transmittance, and when converted to a thickness of 2.00 mm, the ultraviolet transmittance Tuv as defined in ISO-9050:2003 is preferably 50% or less. Tuv is more preferably 40% or less, and even more preferably 20% or less. Also, Tuv is, for example, 10% or more.

[0129] Furthermore, when the glass plate of this embodiment is converted to a thickness of 2.00 mm, it is defined in JIS Z 8781-4 when using a D65 light source. * -5.0 or higher is preferred, -3.0 or higher is more preferred, and -2.0 or higher is even more preferred. Also, a * It is preferably 2.0 or less, more preferably 1.0 or less, and even more preferably 0 or less.

[0130] Furthermore, when the thickness is converted to 2.00 mm, the b defined in JIS Z 8781-4 using a D65 light source * A value of -5.0 or higher is preferred, -3.0 or higher is more preferred, and -1.0 or higher is even more preferred. Also, b * The ratio is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. The glass plate of this embodiment is a * and b * Because it falls within the above range, it offers superior design qualities for architectural and vehicle window glass.

[0131] The method for manufacturing the glass plate in this embodiment is not particularly limited, but for example, a glass plate formed by the known float method is preferred. In the float method, a molten glass base is floated on a molten metal such as tin, and a glass plate with uniform thickness and width is formed by precise temperature control.

[0132] Alternatively, glass plates formed by known roll-out or down-draw methods may be used, and the surface may be polished, resulting in a glass plate with a uniform thickness.

[0133] The down-draw method is broadly divided into the slot down-draw method and the overflow down-draw method (fusion method), but both are techniques in which molten glass is continuously poured down from a molded body to form a strip-shaped glass ribbon.

[0134] The glass plate in this embodiment may be air-cooled strengthened. Air-cooled strengthened glass is a glass plate that has been heat-strengthened. Heat strengthening involves rapidly cooling a uniformly heated glass plate from a temperature near its softening point, generating compressive stress on the glass surface due to the temperature difference between the glass surface and the interior of the glass. The compressive stress is generated uniformly across the entire surface of the glass, forming a compressive stress layer of uniform depth across the entire surface of the glass. Heat strengthening is more suitable for strengthening thick glass plates than chemical strengthening.

[0135] Normally, glass with low alkali content or no alkali at all has a small average coefficient of thermal expansion, making it difficult to temper with air cooling. However, the glass plate of this embodiment has a larger average coefficient of thermal expansion than conventional glass with low alkali content or no alkali at all, making it possible to temper it with air cooling.

[0136] [Laminated glass] The laminated glass according to an embodiment of the present invention comprises a first glass plate, a second glass plate, and an interlayer sandwiched between the first glass plate and the second glass plate, wherein at least one of the first glass plate and the second glass plate is the glass plate described above.

[0137] Figure 1 shows an example of laminated glass 10 according to this embodiment. The laminated glass 10 comprises a first glass plate 11, a second glass plate 12, and an interlayer 13 sandwiched between the first glass plate 11 and the second glass plate 12.

[0138] The laminated glass 10 according to this embodiment is not limited to the configuration shown in Figure 1, and can be modified without departing from the spirit of the present invention. For example, the interlayer 13 may be formed as a single layer as shown in Figure 1, or as two or more layers. Furthermore, the laminated glass 10 according to this embodiment may have three or more glass plates, in which case an organic resin or the like may be interposed between adjacent glass plates. Hereinafter, the laminated glass 10 according to this embodiment will be described as having only two glass plates, a first glass plate 11 and a second glass plate 12, with the interlayer 13 sandwiched between them.

[0139] In the laminated glass of this embodiment, from the viewpoint of radio wave transmittance and bendability, it is preferable to use the above-mentioned glass plates for both the first glass plate 11 and the second glass plate 12. In this case, the first glass plate 11 and the second glass plate 12 may be glass plates of the same composition, or they may be glass plates of different compositions.

[0140] If one of the first glass plate 11 and the second glass plate 12 is not the type of glass plate described above, the type of glass plate is not particularly limited, and conventionally known glass plates used for vehicle windows and the like can be used. Specifically, examples include alkali aluminosilicate glass and soda-lime glass. These glass plates may or may not be colored, as long as their transparency is not impaired.

[0141] Furthermore, in the laminated glass of this embodiment, one of the first glass plate 11 and the second glass plate 12 may be alkali aluminosilicate glass containing 1.0% or more Al2O3. By using the above-mentioned alkali aluminosilicate glass for either the first glass plate 11 or the second glass plate 12, chemical strengthening becomes possible, as described later, and the strength can be increased.

[0142] From the viewpoint of weather resistance and chemical strengthening, the above-mentioned alkali aluminosilicate glass is more preferably having an Al2O3 content of 2.0% or more, and even more preferably 2.5% or more. Furthermore, since a high Al2O3 content in alkali aluminosilicate glass may reduce the millimeter-wave radio wave transmittance, the Al2O3 content is preferably 20% or less, and more preferably 15% or less.

[0143] From the viewpoint of chemical strengthening, the above alkali aluminosilicate glass preferably has an R2O content of 10% or more, more preferably 12% or more, and even more preferably 13% or more.

[0144] Furthermore, in alkali aluminosilicate glass, a high R2O content may reduce the millimeter-wave radio wave transmittance; therefore, the R2O content is preferably 25% or less, more preferably 20% or less, and even more preferably 19% or less. Here, R2O represents Li2O, Na2O, or K2O.

[0145] The alkali aluminosilicate glass mentioned above can be exemplified by the following compositions. Each component is expressed in mole percentage based on the oxide. 61% ≤ SiO2 ≤ 77% 1.0% ≤ Al2O3 ≤ 20% 0.0% ≤ B2O3 ≤ 10% 0.0% ≤ MgO ≤ 15% 0.0% ≤ CaO ≤ 10% 0.0% ≤ SrO ≤ 1.0% 0.0% ≤ BaO ≤ 1.0% 0.0% ≤ Li2O ≤ 15% 2.0% ≤ Na2O ≤ 15% 0.0% ≤ K2O ≤ 6.0% 0.0% ≤ ZrO2 ≤ 4.0% 0.0% ≤ TiO2 ≤ 1.0% 0.0% ≤ Y2O3 ≤ 2.0% 10% ≤ R2O ≤ 25% 0.0% ≤ RO ≤ 20% (R2O represents the total amount of Li2O, Na2O, and K2O, while RO represents the total amount of MgO, CaO, SrO, and BaO.)

[0146] Furthermore, in the laminated glass of this embodiment, one of the first glass plate 11 and the second glass plate 12 may be soda-lime glass. The soda-lime glass may be soda-lime glass containing less than 1.0% Al2O3. Specifically, the following glass compositions can be exemplified. 60% ≤ SiO2 ≤ 75% 0.0% ≤ Al2O3 < 1.0% 2.0% ≤ MgO ≤ 11% 2.0% ≤ CaO ≤ 10% 0.0% ≤ SrO ≤ 3.0% 0.0% ≤ BaO ≤ 3.0% 10% ≤ Na2O ≤ 18% 0.0% ≤ K2O ≤ 8.0% 0.0% ≤ ZrO2 ≤ 4.0% 0.0010% ≤ Fe2O3 ≤ 5.0%

[0147] The lower limit of the thickness of the first glass plate 11 or the second glass plate 12 is preferably 0.50 mm or more, more preferably 0.70 mm or more, even more preferably 1.00 mm or more, particularly preferably 1.20 mm or more, and most preferably 1.50 mm or more. A thickness of 0.50 mm or more for the first glass plate 11 or the second glass plate 12 is preferable from the viewpoint of impact resistance.

[0148] Furthermore, the upper limit of the thickness of the first glass plate 11 or the second glass plate 12 is preferably 3.70 mm or less, more preferably 3.50 mm or less, even more preferably 3.20 mm or less, even more preferably 3.00 mm or less, particularly preferably 2.50 mm or less, and most preferably 2.20 mm or less.

[0149] If the thickness of the first glass plate 11 or the second glass plate 12 is 3.70 mm or less, the weight of the laminated glass 10 does not become too large, which is preferable in terms of improving fuel efficiency when used in a vehicle.

[0150] Furthermore, the thicknesses of the first glass plate 11 and the second glass plate 12 may be the same or different.

[0151] In the laminated glass 10 of this embodiment, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is preferably 2.30 mm or more. Sufficient strength can be obtained with a total thickness of 2.30 mm or more. The total thickness is more preferably 2.50 mm or more, even more preferably 2.70 mm or more, even more preferably 3.00 mm or more, particularly preferably 3.50 mm or more, and most preferably 4.00 mm or more.

[0152] Furthermore, from the viewpoint of improving radio wave transparency and reducing weight, the total thickness may be 5.00 mm or less, preferably 4.90 mm or less, more preferably 4.85 mm or less, and even more preferably 4.80 mm or less.

[0153] In the laminated glass 10 of this embodiment, the thickness of the first glass plate 11 and the second glass plate 12 may be constant throughout the entire surface, or it may vary from place to place as needed, such as by forming a wedge shape in which the thickness of one or both of the first glass plate 11 and the second glass plate 12 gradually decreases.

[0154] One of the first glass plate 11 and the second glass plate 12 may be a chemically strengthened glass that has been glass-strengthened to improve its strength. A method for chemical strengthening is, for example, ion exchange. In ion exchange, the glass plate is immersed in a treatment solution (e.g., potassium nitrate molten salt) and compressed stress is generated on the glass surface by exchanging ions with small ionic radii (e.g., Na ions) for ions with large ionic radii (e.g., K ions). The compressed stress is generated uniformly across the entire surface of the glass plate, forming a compressive stress layer of uniform depth across the entire surface of the glass plate.

[0155] The magnitude of the compressive stress on the surface of the glass plate (hereinafter also referred to as surface compressive stress CS) and the depth DOL of the compressive stress layer formed on the surface of the glass plate can be adjusted by the glass composition, chemical strengthening treatment time, and chemical strengthening treatment temperature, respectively. Chemically strengthened glass can be obtained by chemically strengthening the alkali aluminosilicate glass described above.

[0156] The shapes of the first glass plate 11 and the second glass plate 12 may be flat or curved, having curvature in all or part of the surface.

[0157] If the first glass plate 11 and the second glass plate 12 are curved, they may be a single-bend shape that curves in only one direction, either vertically or horizontally, or a double-bend shape that curves in both vertically or horizontally.

[0158] If the first glass plate 11 and the second glass plate 12 have a double-curved shape, the radii of curvature in the vertical direction and the horizontal direction may be the same or different.

[0159] If the first glass plate 11 and the second glass plate 12 are curved, the radius of curvature in the vertical and / or horizontal directions is preferably 1000 mm or more.

[0160] The shape of the main surfaces of the first glass plate 11 and the second glass plate 12 is such that, for example in the case of vehicle window glass, it conforms to the shape of the window opening of the vehicle in which it is installed.

[0161] The interlayer 13 in this embodiment is sandwiched between the first glass plate 11 and the second glass plate 12. The laminated glass 10 of this embodiment, by including the interlayer 13, firmly adheres the first glass plate 11 and the second glass plate 12 and can mitigate the impact force when flying fragments collide with the glass plate.

[0162] As the interlayer 13, various organic resins commonly used in laminated glass for conventional vehicles can be used. For example, polyethylene (PE), ethylene vinyl acetate copolymer (EVA), polypropylene (PP), polystyrene (PS), methacrylic resin (PMA), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), cellulose acetate (CA), diallyl phthalate resin (DAP), urea resin (UP), melamine resin (MF), unsaturated polyester (UP), polyvinyl butyral (PVB), polyvinyl formal ( Materials such as PVF, polyvinyl alcohol (PVAL), vinyl acetate resin (PVAc), ionomer (IO), polymethylpentene (TPX), vinylidene chloride (PVDC), polysulfone (PSF), polyvinylidene fluoride (PVDF), methacrylic styrene copolymer resin (MS), polyalate (PAR), polyallyl sulfone (PASF), polybutadiene (BR), polyethersulfone (PESF), or polyetheretherketone (PEEK) can be used. Among these, EVA and PVB are preferred from the viewpoint of transparency and adhesion, and PVB is particularly preferred because it can provide sound insulation.

[0163] The thickness of the interlayer 13 is preferably 0.30 mm or more, more preferably 0.50 mm or more, and even more preferably 0.70 mm or more, from the viewpoint of impact force mitigation and sound insulation.

[0164] Furthermore, the thickness of the interlayer 13 is preferably 1.00 mm or less, more preferably 0.90 mm or less, and even more preferably 0.80 mm or less, from the viewpoint of suppressing a decrease in visible light transmittance.

[0165] Furthermore, the thickness of the interlayer 13 is preferably in the range of 0.30 mm to 1.00 mm, and more preferably in the range of 0.70 mm to 0.80 mm.

[0166] The interlayer 13 may have a uniform thickness across the entire surface, or its thickness may vary from place to place as needed.

[0167] Furthermore, if the difference in the coefficient of linear expansion between the interlayer 13 and the first glass plate 11 or the second glass plate 12 is large, cracks or warping may occur in the laminated glass 10 when it is manufactured through the heating process described later, potentially leading to a defective appearance.

[0168] Therefore, it is preferable that the difference between the coefficient of linear expansion of the interlayer 13 and the first glass plate 11 or the second glass plate 12 be as small as possible. The difference between the coefficient of linear expansion of the interlayer 13 and the first glass plate 11 or the second glass plate 12 may be expressed as the difference between the average coefficients of thermal expansion over a predetermined temperature range.

[0169] In particular, since the resin constituting the interlayer 13 has a low glass transition temperature, a predetermined average thermal expansion coefficient difference may be set within a temperature range below the glass transition temperature of the resin material. The difference in linear expansion coefficients between the first glass plate 11 or the second glass plate 12 and the resin material may also be set by a predetermined temperature below the glass transition temperature of the resin material.

[0170] Furthermore, the interlayer 13 may also be an adhesive layer containing an adhesive, and the adhesive is not particularly limited, but for example, an acrylic adhesive or a silicone adhesive can be used.

[0171] When the interlayer 13 is an adhesive layer, there is no need to go through a heating process in the bonding process between the first glass plate 11 and the second glass plate 12, so there is less risk of the above-mentioned cracking or warping occurring.

[0172] [Other layers] The laminated glass 10 of the embodiment of the present invention may include layers other than the first glass plate 11, the second glass plate 12, and the interlayer 13 (hereinafter also referred to as "other layers"), to the extent that they do not impair the effects of the present invention. For example, it may include a coating layer that provides water-repellent, hydrophilic, or anti-fogging functions, or an infrared reflective film.

[0173] The location of the other layers is not particularly limited and may be provided on the surface of the laminated glass 10, or may be provided sandwiched between the first glass plate 11, the second glass plate 12, or the interlayer 13. Furthermore, the laminated glass 10 of this embodiment may include a black ceramic layer or the like, which is arranged in a strip shape on part or all of the peripheral edge for the purpose of concealing attachment parts to frames, wiring conductors, etc.

[0174] The manufacturing method for the laminated glass 10 according to the embodiment of the present invention can be the same as that for conventionally known laminated glass. For example, by stacking a first glass plate 11, an interlayer 13, and a second glass plate 12 in this order, and then going through the steps of heating and pressurizing, a laminated glass 10 can be obtained in which the first glass plate 11 and the second glass plate 12 are joined via the interlayer 13.

[0175] The manufacturing method for the laminated glass 10 according to an embodiment of the present invention may involve, for example, a step of heating and shaping the first glass plate 11 and the second glass plate 12, followed by a step of inserting the interlayer 13 between the first glass plate 11 and the second glass plate 12, and then heating and pressurizing the interlayer. By going through such a process, the laminated glass 10 may be configured such that the first glass plate 11 and the second glass plate 12 are joined via the interlayer 13.

[0176] In the embodiment of the present invention, the laminated glass 10 has a total thickness of 5.00 mm or less for the first glass plate 11, the second glass plate 12, and the interlayer 13, and preferably the visible light transmittance Tv, as defined in ISO-9050:2003 using a D65 light source, is 70% or more. Tv is more preferably 71% or more, and even more preferably 72% or more. Also, Tv is, for example, 90% or less.

[0177] In the laminated glass 10 according to the embodiment of the present invention, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is 5.00 mm or less, and the total solar radiation transmittance Tts, as defined in ISO-13837:2008 convention A and measured at a wind speed of 4 m / s, is preferably 70% or less. By having a total solar radiation transmittance Tts of 70% or less in the laminated glass 10 according to the embodiment of the present invention, sufficient heat shielding performance can be obtained.

[0178] The above Tts is more preferably 68% or less, and even more preferably 66% or less. Also, Tts is, for example, 55% or more.

[0179] In the laminated glass 10 according to the embodiment of the present invention, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is 5.00 mm or less, and the maximum value of the radio wave transmission loss S21 when radio waves with a frequency of 75 GHz to 80 GHz are incident on the first glass plate 11 at an incident angle of 60° is preferably -4.0 dB or more.

[0180] The maximum value of the radio wave transmission loss S21 under the above conditions is preferably -3.0 dB or higher, and more preferably -2.5 dB or higher. Furthermore, the maximum value of the radio wave transmission loss S21 under the above conditions is, for example, -0.50 dB or lower.

[0181] Here, the radio wave transmission loss S21 is the relative permittivity (ε) of each material used in laminated glass. r This refers to the insertion loss derived based on the dielectric loss tangent (tanδ) (where δ is the loss angle), and the smaller the absolute value of the radio wave transmission loss S21, the higher the radio wave transmission.

[0182] Furthermore, the angle of incidence refers to the angle between the normal to the main surface of the laminated glass 10 and the direction of incidence of the radio waves.

[0183] In the laminated glass 10 according to the embodiment of the present invention, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is 5.00 mm or less, and the maximum value of the radio wave transmission loss S21 when radio waves with a frequency of 75 GHz to 80 GHz are incident on the first glass plate 11 at an incident angle of 45° is preferably -4.0 dB or more.

[0184] The maximum value of the radio wave transmission loss S21 under the above conditions is preferably -3.0 dB or higher, and more preferably -2.5 dB or higher. Furthermore, the maximum value of the radio wave transmission loss S21 under the above conditions is, for example, -0.50 dB or lower.

[0185] In the laminated glass 10 according to the embodiment of the present invention, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is 5.00 mm or less, and the maximum value of the radio wave transmission loss S21 when radio waves with a frequency of 75 GHz to 80 GHz are incident on the first glass plate 11 at an incident angle of 20° is preferably -4.0 dB or more.

[0186] The maximum value of the radio wave transmission loss S21 under the above conditions is preferably -3.0 dB or higher, and more preferably -2.5 dB or higher. Furthermore, the maximum value of the radio wave transmission loss S21 under the above conditions is, for example, -0.50 dB or lower.

[0187] The laminated glass 10 according to an embodiment of the present invention has a total thickness of 5.00 mm or less for the first glass plate 11, the second glass plate 12, and the interlayer 13, and uses a D65 light source and has a chromaticity a as defined in JIS Z 8781-4. * -8.0 or higher is preferred, -7.0 or higher is more preferred, and -6.0 or higher is even more preferred. Also, a * It is preferably 2.0 or less, more preferably 1.0 or less, and even more preferably 0 or less.

[0188] Furthermore, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is 5.00 mm or less, and the chromaticity b as defined in JIS Z 8781-4 is measured using a D65 light source. * A value of -5.0 or higher is preferred, -3.0 or higher is more preferred, and -1.0 or higher is even more preferred.

[0189] Also, b * Preferably, the value is 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less.

[0190] The glass plate of this embodiment is a * and b * Because it falls within the above range, it offers superior design qualities for architectural and vehicle window glass.

[0191] [Architectural window glass, vehicle window glass] The architectural window glass and vehicle window glass of this embodiment have the above-mentioned glass plate. Alternatively, the architectural window glass and vehicle window glass of this embodiment may be made of the above-mentioned laminated glass.

[0192] The following describes an example of using the laminated glass 10 of this embodiment as a vehicle window glass, with reference to the drawings.

[0193] Figure 2 is a conceptual diagram showing the laminated glass 10 of this embodiment being installed in an opening 110 formed at the front of the automobile 100 and used as a window glass for the automobile. The laminated glass 10 used as a window glass for the automobile may have a housing (case) 120 containing information devices, etc., attached to its inner surface to ensure the safety of the vehicle while driving.

[0194] Furthermore, the information devices housed within the housing are devices that use cameras, radar, etc., to prevent rear-end collisions and impacts with vehicles, pedestrians, obstacles, etc., in front of the vehicle, and to warn the driver of danger. Examples include information receiving devices and / or information transmitting devices, which include millimeter-wave radar, stereo cameras, infrared lasers, etc., and perform signal transmission and reception. The "signals" refer to electromagnetic waves, including millimeter waves, visible light, infrared light, etc.

[0195] Figure 3 is an enlarged view of portion S in Figure 2, and is a perspective view showing the portion where the housing 120 is attached to the laminated glass 10 of this embodiment. The housing 120 houses a millimeter-wave radar 201 and a stereo camera 202 as information devices. The housing 120, which houses the information devices, is usually mounted on the outside of the vehicle from the rearview mirror 150 and on the inside of the vehicle from the laminated glass 10, but it may be mounted on other parts as well.

[0196] Figure 4 is a cross-sectional view taken in a direction perpendicular to the horizontal line, including the YY line in Figure 3. In the laminated glass 10, the first glass plate 11 is positioned on the outside of the vehicle. As described above, the angle of incidence θ of the radio waves 300 used for communication of information devices such as millimeter-wave radar 201 to the main surface of the first glass plate 11 can be evaluated as, for example, 20°, 45°, 60°, etc. [Examples]

[0197] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0198] <Preparation of glass plates for Examples 1 to 42> The raw materials were placed in a platinum crucible and melted at 1650°C for 3 hours to obtain molten glass with the glass composition (unit: mol%) shown in Tables 1 to 4. The molten glass was poured onto a carbon plate and slowly cooled. Both sides of the resulting plate-like glass were polished to obtain a glass plate with a thickness of 2.00 mm. Examples 1 to 8 are comparative examples, and Examples 9 to 42 are examples. In Tables 1 to 4, in addition to the composition, the amounts of C, F, and SO3 added as raw materials are shown. The amounts of C, F, and SO3 represent the relative amounts (unit: mass%) of C, F, and SO3 added during the melting of the glass raw materials, relative to 100 mass% of the total glass raw materials: SiO2, Al2O3, B2O3, P2O5, MgO, CaO, SrO, BaO, ZnO, Li2O, Na2O, K2O, ZrO2, and Fe2O3.

[0199] The method for determining the values ​​shown in Tables 1 to 4 is described below. (1) Glass transition temperature (Tg): The values ​​were measured using TMA and determined according to the JIS R3103-3 standard (2001).

[0200] (2) Average thermal expansion coefficient (CTE(50-350)) between 50°C and 350°C: The values ​​were measured using a differential thermal expander (TMA) and determined according to the JIS R3102 standard (1995 edition).

[0201] (3) Viscosity: The viscosity η was measured using a rotational viscometer and was 10 2 The temperature T2 (reference temperature for solubility) at which the viscosity η becomes dPa·s is 10 4 The temperature T4 (reference temperature for moldability) at which the viscosity η is dPa·s was measured. 7.65 Temperature T when the temperature is dPa·s 7.65 The softening point was determined according to the JIS R3103-1 standard (2001). Viscosity η = 10 12 Temperature T when the temperature is dPa·s 12 The reference temperature for bendability was measured using the beam bending method.

[0202] (4) Density: A 20g glass block, free of bubbles and cut from a glass plate, was measured using the Archimedes method.

[0203] (5) Young's modulus: Measurements were taken at 25°C using the ultrasonic pulse method (Olympus, DL35).

[0204] (6) Specific permittivity (ε r ), dielectric loss tangent (tanδ): Using the Split Post Dielectric Resonator (SPDR) method manufactured by QWED, the relative permittivity (ε) of a frequency of 10 GHz was measured under conditions of slow cooling at 1°C / min. r The dielectric loss tangent (tanδ) was measured.

[0205] (7) Visible light transmittance (Tv): Tv when converted to a thickness of 2.00 mm was measured by the method defined in ISO-9050:2003 using a D65 light source. Note that Tv was measured using a spectrophotometer LAMBDA950 manufactured by Perkinelmer.

[0206] (8) Global solar transmittance (Tts): Tts when converted to a thickness of 2.00 mm was obtained by the method defined in ISO-13837:2008 convention A and measured at a wind speed of 4 m / s. Note that Tts was measured using a spectrophotometer LAMBDA950 manufactured by Perkinelmer.

[0207] (9) Ultraviolet transmittance (Tuv): Tuv when converted to a thickness of 2.00 mm was measured by the method defined in ISO-9050:2003. Note that Tuv was measured using a spectrophotometer LAMBDA950 manufactured by Perkinelmer.

[0208] (10) Chromaticity (a * , b * ): The chromaticity a * , b * defined in JIS Z 8781-4 was measured using a D65 light source.

[0209] The measurement results are shown in Tables 1 to 4. Note that in Tables 1 to 4, "-" indicates unmeasured.

[0210]

Table 1

[0211]

Table 2

[0212]

Table 3

[0213] [Table 4]

[0214] The glass plates in Examples 9 to 42, which correspond to the embodiments, have a relative permittivity (ε) at a frequency of 10 GHz. r The viscosity η was 6.5 or less, and the dielectric loss tangent (tanδ) at a frequency of 10 GHz was 0.009 or less, indicating good radio wave transmission. In addition, the viscosity η was 10 12 Temperature T when the temperature is dPa·s 12 The temperature is 730°C or lower, and the average thermal expansion coefficient between 50°C and 350°C is 40 × 10⁻⁶. -7 The temperature was above / K, indicating that bending and forming are possible at low temperatures.

[0215] On the other hand, the glass plate in Example 1, which corresponds to the comparative example, has a high R2O content, so the relative permittivity at a frequency of 10 GHz is (ε r The coefficient of dispersion () exceeded 6.5, and the dielectric loss tangent (tanδ) at a frequency of 10 GHz exceeded 0.009, indicating poor radio wave penetration.

[0216] Furthermore, the glass plate in Example 2, which corresponds to the comparative example, has B2O3-Al2O3<0.0 and Al2O3 / RO>0.50, so T 12 The temperature exceeds 730°C, and the average thermal expansion coefficient between 50°C and 350°C is 40 × 10⁻⁶. -7 The temperature was less than / K, indicating insufficient bending formability at low temperatures. Furthermore, due to the low Fe2O3 content, the total solar radiation transmittance Tts was high, resulting in poor heat shielding properties.

[0217] Furthermore, the glass plates in Examples 3 to 8, which correspond to comparative examples, showed cloudiness due to their low Al2O3 / RO ratio.

[0218] <Fabrication of laminated glass> Laminated glass products for Manufacturing Examples 1 to 17 were manufactured using the following procedure. Manufacturing Examples 1 to 2 are comparative examples, and Manufacturing Examples 3 to 17 are examples.

[0219] (Manufacturing Example 1) As the first glass plate and the second glass plate, a glass plate (Example 1) with a thickness of 2.00 mm and having the composition shown in Table 1 was used. As the interlayer film, polyvinyl butyral with a thickness of 0.76 mm was used. The first glass plate, the interlayer film, and the second glass plate were laminated in this order, and a pressure bonding treatment (1 MPa, 130 °C, 3 hours) was performed using an autoclave to produce the laminated glass of Production Example 1. The laminated glass of Production Example 1 had a total thickness of 4.76 mm for the first glass plate, the second glass plate, and the interlayer film.

[0220] (Production Examples 2 to Production Example 17) Except for the points shown in Table 5 and Table 6, laminated glasses of Production Examples 2 to Production Example 17 were produced in the same manner as in Production Example 1.

[0221] [Optical Properties] Regarding the visible light transmittance (Tv), in the same manner as above, it was measured by the method defined in ISO - 9050:2003 using a D65 light source. Regarding the total solar energy transmittance (Tts), in the same manner as above, it was measured by the method defined in ISO - 13837:2008 convention A and measured at a wind speed of 4 m / s. Regarding the ultraviolet transmittance (Tuv), in the same manner as above, it was measured by the method defined in ISO - 9050:2003. Also, regarding the chromaticity (a * , b * ), in the same manner as above, the chromaticity a * , b * defined in JIS Z 8781 - 4 was measured using a D65 light source. The results are shown in Table 5 and Table 6.

[0222] [Radio Wave Transmittance] Regarding the laminated glasses of Production Examples 1 to Production Example 17, when a TM wave with a frequency of 76 GHz, 77 GHz, 78 GHz, or 79 GHz was incident at an incident angle of 20 °, 45 °, or 60 °, the radio wave transmission loss S21 was calculated based on the relative permittivity (ε rThe values ​​were calculated based on the dielectric loss tangent (tanδ). Specifically, antennas were placed facing each other, and each of the resulting laminated glass panels was installed between them so that the incident angle was from 0° to 60°. Then, for TM waves with frequencies from 76GHz to 79GHz, the radio wave transmission loss S21 was measured at a 100mmΦ aperture, with the case without a radio wave-transparent substrate being set to 0[dB], and the radio wave transparency was evaluated according to the following criteria.

[0223] <Evaluation of radio wave transparency> A: -1.5 [dB] ≤ S21 B: -2.0 [dB] ≤ S21 < -1.5 [dB] C: -2.5[dB] ≤ S21 < -2.0[dB] D: -3.0 [dB] ≤ S21 < -2.5 [dB] E: -4.0[dB] ≤ S21 < -3.0[dB] ×: S21 < -4.0 [dB] The results are shown in Tables 5 and 6.

[0224] [Table 5]

[0225] [Table 6]

[0226] The laminated glass examples 3 to 17, which correspond to the embodiments, all had a total solar radiation transmittance Tts of 70% or less, demonstrating good heat shielding properties.

[0227] Furthermore, the laminated glass in manufacturing examples 3 to 17 exhibited excellent radio wave transmission performance, with a maximum value of -4.0 dB or higher for radio wave transmission loss S21 at incident angles of 20°, 45°, or 60° and incident frequencies of 76 GHz, 77 GHz, 78 GHz, or 79 GHz.

[0228] Thus, it was found that the laminated glass of manufacturing examples 3 to 17 has high millimeter-wave transmittance and the specified heat shielding properties.

[0229] While the laminated glass in manufacturing examples 3 to 16 all had high visible light transmittance Tv of 70% or more, indicating good performance, the laminated glass in manufacturing example 17 had a total thickness of over 5.00 mm for the first glass plate, second glass plate, and interlayer, resulting in a visible light transmittance Tv of less than 70%.

[0230] On the other hand, the laminated glass of Manufacturing Example 1, which corresponds to the comparative example, had inferior radio wave transmission loss S21, with a maximum value of less than -4.0 dB for incident frequencies of 76 GHz, 77 GHz, 78 GHz, or 79 GHz at incident angles of 20°, 45°, or 60°.

[0231] Furthermore, the laminated glass in manufacturing example 2, which corresponds to a comparative example, had a total solar radiation transmittance Tts exceeding 70%, indicating poor heat shielding performance.

[0232] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0233] This application is based on the Japanese Patent Application No. 2020-210647 filed on December 18, 2020, and its contents are incorporated herein by reference. [Explanation of symbols]

[0234] 10 Laminated glass 11. First glass plate 12. Second glass plate 13 Interlayer 100 automobiles 110 Opening 120 Housing 150 Rearview mirror 201 mm wave radar 202 Stereo Camera 300 radio waves

Claims

1. Expressed as a mole percentage based on oxides, 50%≦SiO ２ ≦80% 5.0% ≦Al ２ O ３ ≦10% 5.0%<B ２ O ３ ≦15% 0.0% ≦ P ２ O ５ ≦10% 0.0% ≤ MgO ≤ 10% 0.0% ≤ CaO ≤ 10% 3.5% ≤ SrO ≤ 10% 0.0% ≤ BaO ≤ 10% 0.0% ≤ ZnO ≤ 5.0% 0.0%≦Li ２ O≦5.0% 0.0%≦Na ２ O≦5.0% 0.0%≦K ２ O≦5.0% 0.0%≦R ２ O≦5.0% Fe ２ O ３ ≧0.04% 19.0% ≤ RO ≤ 30% B ２ O ３ -Al ２ O ３ >0.0% 0.30<Al ２ O ３ / RO<0.50 Contains (R ２ O is Li ２ O, Na ２ O, K ２ (The total amount of O is represented by RO, which represents the total amount of MgO, CaO, SrO, and BaO.) Glass viscosity is 10 １２ Temperature T at which dPa·s occurs １２ The temperature is below 730°C. The average coefficient of thermal expansion between 50°C and 350°C is 40 × 10⁻⁶. －７ / K or greater, Glass plate.

2. The temperature T １２ The glass plate according to claim 1, wherein the temperature is 720°C or lower.

3. Relative permittivity (ε) at a frequency of 10 GHz ｒ The glass plate according to claim 1 or 2, wherein the coefficient of gravity is 6.5 or less.

4. A glass plate according to any one of claims 1 to 3, wherein the dielectric loss tangent (tanδ) at a frequency of 10 GHz is 0.0090 or less.

5. A glass plate according to any one of claims 1 to 4, wherein, when the thickness is converted to 2.00 mm, the visible light transmittance Tv as defined in ISO-9050:2003 using a D65 light source is 75% or more.

6. A glass plate according to any one of claims 1 to 5, wherein, when converted to a thickness of 2.00 mm, the total solar radiation transmittance Tts, as defined in ISO-13837:2008 convention A and measured at a wind speed of 4 m / s, is 88% or less.

7. The glass plate according to claim 6, wherein the total solar radiation transmittance Tts is 80% or less.

8. Expressed as a mole percentage based on oxides, 55%≦SiO ２ ≦70% 6.0% ≦Al ２ O ３ ≦8.0% 7.0% ≦B ２ O ３ ≦12% 0.0% ≦ P ２ O ５ ≦5.0% 2.0% ≤ MgO ≤ 7.0% 2.0% ≤ CaO ≤ 7.0% 3.5% ≤ SrO ≤ 7.0% 2.0% ≤ BaO ≤ 7.0% 0.0% ≤ ZnO ≤ 3.0% 0.04% ≦Fe ２ O ３ ≦0.50% 19.0% ≤ RO ≤ 25% 0.0%≦R ２ O≦3.0% A glass plate according to any one of claims 1 to 7, comprising the same material.

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