Laminated glass for vehicles

Abstract

The present invention pertains to a laminated glass for a vehicle, said laminated glass comprising a first glass sheet, a second glass sheet and an intermediate film sandwiched between the first glass sheet and the second glass sheet, wherein: the total thickness of the first glass sheet, the second glass sheet and the intermediate film is 4.0 mm or more; the first glass sheet is formed of a borosilicate glass containing, in terms of oxide by molar percentage, 1.0% or more of B2O3; and when a radio wave (TM wave) with a frequency of 79[GHz] is made incident at an incident angle of 60° to the first glass sheet, the transmission property S21 is -4.0 [dB] or more.

Description

[Technical Field]

[0001] The present invention relates to a laminated glass for a vehicle. [Background technology]

[0002] In recent years, in addition to communications using microwave and millimeter wave wavelengths, there has been a trend toward the expansion of high-speed, large-capacity communications infrastructure, such as 4G LTE and 5G, and the bands in use are expanding from the 3 GHz band to the 5-80 GHz band. Antennas with good directionality and reception sensitivity are therefore required, including for these frequency bands. Furthermore, Vehicle-to-Everything (V2X) is expected to be used for vehicle-to-vehicle and road-to-vehicle communications, and is being deployed for a variety of purposes, such as the use of the 5.9 GHz band in ETC in Europe.

[0003] To perform such high-frequency band communications, an in-vehicle radar (millimeter-wave radar) installed inside a vehicle emits radio waves at a frequency of, for example, 76.5 GHz. Such millimeter-wave radio waves are significantly reflected by ordinary vehicle glass, particularly the windshield. For this reason, a radar window made of a resin with a lower dielectric constant than glass is provided in part of the windshield to reduce reflection loss when the radar passes through the radar window and increase the transmittance of transmitted and received waves (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-181480 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the configuration of Patent Document 1 improves millimeter-wave radar transparency, it has the drawback of requiring more complicated windshield processing.It also has the drawback of impairing the quality required of a windshield, such as reducing its strength against external impacts such as flying stones while driving (hereinafter referred to as chipping resistance or flying stone strength).

[0006] The present invention provides a laminated glass for vehicles that satisfies the required quality for strength required of conventional windshields, has a simple structure, and is excellent in transmittance of radio waves in high frequency bands such as those used by millimeter wave radar. [Means for solving the problem]

[0007] A laminated glass for vehicles according to an embodiment of the present invention includes a first glass plate, a second glass plate, and an interlayer film sandwiched between the first glass plate and the second glass plate, wherein the total thickness of the first glass plate, the second glass plate, and the interlayer film is 4.0 mm or more, the first glass plate is borosilicate glass containing 1.0% or more B2O3 expressed as an oxide-based mole percentage, and the laminated glass for vehicles has a transmission characteristic S21 of -4.0 dB or more when TM radio waves with a frequency of 79 GHz are incident on the first glass plate at an incident angle of 60°.

[0008] In addition, in the laminated glass for vehicles according to one aspect of the present invention, the transmission characteristic S21 may be −3.1 dB or more when a TM wave having a frequency of 79 GHz is incident on the first glass plate at an incident angle of 67.5°.

[0009] In addition, in the laminated glass for vehicles according to one aspect of the present invention, the transmission characteristic S21 may be −2.0 dB or more when a TM wave having a frequency of 28 GHz is incident on the first glass plate at an incident angle of 0° to 70°.

[0010] In addition, in the laminated glass for vehicles according to one aspect of the present invention, the transmission characteristic S21 may be −0.28 dB or more when a TM wave having a frequency of 28 GHz is incident on the first glass plate at an incident angle of 67.5°.

[0011] In addition, in the laminated glass for vehicles according to one aspect of the present invention, the transmission characteristic S21 may be −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident on the first glass plate at an incident angle of 45°.

[0012] In addition, in the laminated glass for vehicles according to one aspect of the present invention, the transmission characteristic S21 may be −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident on the first glass plate at an incident angle of 20°.

[0013] In the laminated glass for vehicles according to one aspect of the present invention, the first glass plate may be thicker than the second glass plate.

[0014] In the laminated glass for vehicles according to one aspect of the present invention, the first glass plate may have a thickness of 2.50 mm or more.

[0015] In the laminated glass for vehicles according to one aspect of the present invention, the second glass plate may have a thickness of 1.50 mm or less.

[0016] In the laminated glass for vehicles according to one aspect of the present invention, the second glass sheet may be alkali aluminosilicate glass containing 1.0% or more Al2O3 expressed as mole percentage based on oxides.

[0017] In the laminated glass for vehicles according to one aspect of the present invention, the second glass plate may be chemically strengthened glass.

[0018] In the laminated glass for vehicles according to one aspect of the present invention, the second glass sheet may be soda-lime glass containing less than 1.0% Al2O3 in terms of mole percentage based on oxides.

[0019] In the laminated glass for vehicles according to one aspect of the present invention, the second glass sheet may be borosilicate glass containing 1.0% or more B2O3 expressed as a mole percentage based on oxides.

[0020] In the laminated glass for vehicles according to one aspect of the present invention, the borosilicate glass of at least one of the first glass sheet and the second glass sheet may have the following composition expressed in mole percentage based on oxides: 80%≦SiO2+Al2O3+B2O3≦98% 60%≦SiO2≦90% 0%≦Al2O3≦10% 1.0%≦B2O3≦25% 1.0%≦R2O≦10% 0%≦RO≦9.0% 0≦Li2O / R2O≦1.0 0≦Na2O / R2O≦0.90 0≦K2O / R2O≦0.70 (RO represents the total amount of LiO, NaO, and KO, and RO represents the total amount of MgO, CaO, SrO, and BaO.)

[0021] In the laminated glass for vehicles according to one aspect of the present invention, the borosilicate glass of at least one of the first glass sheet and the second glass sheet may have the following composition expressed in mole percentage based on oxides: 72%≦SiO2+Al2O3+B2O3≦98% 55%≦SiO2≦80% 0%≦Al2O3≦20% 1.0%≦B2O3≦25% 0%≦R2O≦5.0% 0%≦RO≦25% (RO represents the total amount of LiO, NaO, and KO, and RO represents the total amount of MgO, CaO, SrO, and BaO.)

[0022] In the laminated glass for vehicles according to one aspect of the present invention, the alkali aluminosilicate glass of the second glass plate may have the following composition expressed in mole percentage on an oxide basis: 61%≦SiO2≦77% 1.0%≦Al2O3≦20% 0%≦B2O3≦10% 0%≦MgO≦15% 0%≦CaO≦10% 0%≦SrO≦1.0% 0%≦BaO≦1.0% 0%≦Li2O≦15% 2.0%≦Na2O≦15% 0%≦K2O≦6.0% 0%≦ZrO2≦4.0% 0%≦TiO2≦1.0% 0%≦Y2O3≦2.0% 10≦R2O≦25 0≦RO≦20 (RO represents the total amount of LiO, NaO, and KO, and RO represents the total amount of MgO, CaO, SrO, and BaO.)

[0023] In the laminated glass for vehicles according to one aspect of the present invention, the interlayer film may be polyvinyl butyral.

[0024] In the laminated glass for vehicles according to one aspect of the present invention, the thickness of the interlayer film may be in the range of 0.30 mm to 1.0 mm.

[0025] Furthermore, the laminated glass for vehicles according to one aspect of the present invention may be one that does not generate cracks of 5.0 mm or more when struck by a pin under the following measurement conditions. <Measurement conditions> ·Collision speed V: 40 [km / h] ·Collision angle β:90[°] Pin: Carbide pin Pin weight: 1.2g Pin tip angle: 90° Pin tip radius: 0.2 mm Planar size of laminated glass sample: 300mm x 300mm Number of replicate tests: 10 [Effects of the Invention]

[0026] The laminated glass for vehicles according to the embodiment of the present invention has high strength and excellent transmittance of radio waves in high frequency bands such as millimeter wave radar. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a cross-sectional view of an example of a laminated glass for vehicles according to an embodiment of the present invention. [Figure 2] Fig. 2(A) is a schematic diagram showing a method for an impact resistance test for evaluating chipping resistance, and Fig. 2(B) is a photograph showing an example of a crack that occurred in a laminated glass after the impact resistance test. [Figure 3] FIG. 3 is a conceptual diagram showing a state in which the laminated glass for vehicles according to the embodiment of the present invention is used as a window glass for an automobile. [Figure 4] FIG. 4 is an enlarged view of the S portion in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line YY in FIG. [Figure 6] FIG. 6 is a graph showing the results of simulation of the transmission characteristics (S21) of the TM wave of frequency F [GHz] incident at an incident angle of 60° for the laminated glass of the example, calculated in the range of 10 [GHz]≦F [GHz]≦90 [GHz]. [Figure 7] FIG. 7 is a graph showing the results of simulation of the transmission characteristics (S21) of the TM wave of frequency F [GHz] incident at an incident angle of 67.5° for the laminated glass of the example, calculated in the range of 10 [GHz]≦F [GHz]≦90 [GHz]. [Figure 8] FIG. 8 is a graph showing the results of calculations performed by simulation of the transmission characteristics (S21) of TM waves with a frequency F of 79 [GHz] incident at an incident angle of 0° to 70° for the laminated glass of the example. [Figure 9] FIG. 9 is a graph showing the results of calculations performed by simulation of the transmission characteristics (S21) of TM waves with a frequency F of 28 [GHz] incident at an incident angle of 0° to 70° for the laminated glass of the example. [Figure 10] FIG. 10 is a graph showing the results of simulation of the transmission characteristics (S21) of the TM wave of frequency F [GHz] incident at an incident angle of 60° for the laminated glass of the example, calculated in the range of 10 [GHz]≦F [GHz]≦90 [GHz]. [Figure 11] FIG. 11 is a graph showing the results of simulation of the transmission characteristics (S21) of TM waves of frequency F [GHz] incident at an incident angle of 60° for a laminated glass of another example, calculated in the range of 10 [GHz]≦F [GHz]≦90 [GHz]. [Figure 12] FIG. 12 is a graph showing the results of simulation of the transmission characteristics (S21) of the TM wave of frequency F [GHz] incident at an incident angle of 67.5° for the laminated glass of the example, calculated in the range of 10 [GHz]≦F [GHz]≦90 [GHz]. [Figure 13] FIG. 13 is a graph showing the results of simulation of the transmission characteristics (S21) of TM waves with a frequency of F [GHz] incident at an incident angle of 67.5° for a laminated glass of another example, calculated within the range of 10 [GHz]≦F [GHz]≦90 [GHz]. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described in detail. In addition, in the following drawings, components and parts that perform the same function may be described with the same reference numerals, and duplicated descriptions may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of an actual product.

[0029] In this specification, unless otherwise specified, evaluations such as "high / low millimeter wave radio wave transmittance" refer to radio wave transmittance including quasi-millimeter waves and millimeter waves, and mean the radio wave transmittance of a laminated glass for a vehicle for frequencies of, for example, 10 GHz to 90 GHz.

[0030] Furthermore, in this specification, unless otherwise specified, the laminated glass for vehicles according to the embodiment of the present invention will be described as being arranged such that, when the laminated glass for vehicles is installed in a vehicle, the first glass plate is arranged on the outside (vehicle exterior side) of the vehicle and the second glass plate is arranged on the inside (interior side) of the vehicle.

[0031] A laminated glass for vehicles (hereinafter simply referred to as laminated glass) according to an embodiment of the present invention includes a first glass sheet, a second glass sheet, and an interlayer film sandwiched between the first and second glass sheets, with the total thickness of the first glass sheet, second glass sheet, and interlayer film being 4.0 mm or more. The first glass sheet is borosilicate glass containing 1.0% or more B2O3, expressed as an oxide-based mole percentage. The laminated glass for vehicles exhibits a transmission characteristic S21 of -4.0 dB or more when a TM wave with a frequency of 79 GHz is incident on the first glass sheet at an incident angle of 60°.

[0032] The laminated glass for vehicles may have a transmission characteristic S21 of -3.1 dB or greater when a TM wave having a frequency of 79 GHz is incident from the first glass plate side at an incident angle of 67.5°. Furthermore, the transmission characteristic S21 may be -2.0 dB or greater when a TM wave having a frequency of 28 GHz is incident from the first glass plate side at an incident angle of 0 to 70°. Furthermore, the transmission characteristic S21 may be -0.28 dB or greater when a TM wave having a frequency of 28 GHz is incident from the first glass plate side at an incident angle of 67.5°.

[0033] Furthermore, the transmission characteristic S21 of the laminated glass for vehicles may be -4.0 dB or more when TM waves with a frequency of 79 GHz are incident from the first glass plate side at an incident angle of either 20° or 45° or both.

[0034] [Laminated glass for vehicles] 1 is a diagram showing an example of a laminated glass for vehicles 10 according to an embodiment of the present invention. The laminated glass for vehicles 10 includes a first glass plate 11, a second glass plate 12, and an interlayer film 13 sandwiched between the first glass plate 11 and the second glass plate 12.

[0035] The laminated glass for vehicles 10 according to this embodiment is not limited to the embodiment shown in Fig. 1 and can be modified within the scope of the present invention. For example, the interlayer film 13 may be formed of one layer as shown in Fig. 1, or may be formed of two or more layers. The laminated glass for vehicles 10 according to this embodiment may have three or more glass sheets, and in that case, an organic resin or the like may be interposed between adjacent glass sheets.

[0036] Hereinafter, the laminated glass 10 for vehicles according to the embodiment will be described as having only two glass plates, a first glass plate 11 and a second glass plate 12, with an interlayer film 13 sandwiched between them.

[0037] In the laminated glass 10 for vehicles according to this embodiment, the first glass sheet 11, the second glass sheet 12, and the interlayer film 13 have a total thickness of 4.0 mm or more. A total thickness of 4.0 mm or more ensures sufficient strength, improving the chipping resistance of the windshield and increasing the rigidity of the vehicle.

[0038] The total thickness is preferably 4.2 mm or more, more preferably 4.4 mm or more, and even more preferably 4.6 mm or more. From the viewpoint of improving radio wave transmittance and reducing weight, the total thickness is preferably 13 mm or less, more preferably 12 mm or less, even more preferably 10 mm or less, still more preferably 8.0 mm or less, particularly preferably 6.0 mm or less, and most preferably 5.0 mm or less.

[0039] In the laminated glass 10 for vehicles according to this embodiment, the first glass plate 11 is a borosilicate glass containing 1.0% or more B2O3 expressed as a mole percentage based on oxides.

[0040] Borosilicate glass has high resistance to flying stones and excellent radio wave transmission properties, so by using borosilicate glass for first glass plate 11, laminated glass 10 has high resistance to flying stones and can have improved radio wave transmission properties.

[0041] Borosilicate glass is an oxide-based glass whose main component is silicon dioxide and also contains boron. The boron component in borosilicate glass is boron oxide (a general term for boron oxides such as diboron trioxide (B2O3)), and the percentage of boron oxide in the glass is expressed in B2O3 equivalents. Similarly, the main components in glass are expressed as oxides such as SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, LiO2, Na2O, and K2O, and their percentages are expressed on an oxide basis.

[0042] In this embodiment, borosilicate glass refers to oxide-based glass containing silicon dioxide as the main component and containing 1.0% or more B2O3 expressed as a mole percentage based on the oxides.

[0043] In addition, in the laminated glass for vehicles 10 according to this embodiment, it is preferable that the transmission characteristic S21 is −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident from the first glass plate 11 side at an incident angle of 60°.

[0044] Furthermore, it is preferable that the laminated glass for vehicles 10 according to this embodiment has a transmission characteristic S21 of −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident from the first glass plate 11 side at an incident angle of either 20° or 45° or both.

[0045] In the laminated glass for vehicles 10 according to this embodiment, the above-mentioned transmission characteristic (S21) is also the characteristic when radio waves of the same frequency are incident at the same angle from the second glass sheet 12 side. In this specification, the transmission characteristic (S21) of the laminated glass for vehicles 10 will be described in terms of the case where millimeter waves of a predetermined frequency are incident from the first glass sheet 11 side.

[0046] When a millimeter-wave radar device installed inside a vehicle communicates with the outside of the vehicle through the windshield, the angle at which radio waves are incident on, for example, the windshield surface varies depending on the structure of the window glass, the communication target, the elevation angle of the millimeter-wave radar's direction of travel, etc.

[0047] However, for a typical automobile, when considering the inclination angle of the windshield relative to the horizontal plane, the incidence angle of the millimeter-wave radar incident on the windshield surface can be set at approximately 60° as a guideline. In this case, the millimeter wave can be, for example, a TM wave of 79 GHz, and the S21 parameter (also called the transmission characteristic S21 or simply S21) is important as an indicator of the millimeter-wave transmittance of automobile window glass. In addition, millimeter waves are also useful for evaluating the transmission characteristic S21 at an incidence angle near 60° (for example, 67.5°).

[0048] Depending on the type of vehicle, the angle of incidence of the millimeter-wave radar incident on the windshield surface may be around 20° or 45°. Therefore, it is useful to evaluate the S21 characteristics for these angles of incidence in the same way, so as to apply it to vehicles with windshields with different installation angles.

[0049] In the evaluation of the transmission characteristic S21, the millimeter wave radar is assumed to travel in a direction parallel to the horizontal plane.

[0050] The transmission characteristic S21 is the relative dielectric constant ε of each material used in the laminated glass. r and the dielectric loss tangent tanδ (δ is the loss angle), and the smaller the absolute value of the transmission characteristic S21, the higher the radio wave transmittance.

[0051] The laminated glass 10 for vehicles according to this embodiment preferably has a transmission characteristic S21 of −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident on the first glass plate 11 at an incident angle of 60°.

[0052] In addition, in the laminated glass 10 for vehicles, when a TM wave having a frequency of 79 [GHz] is incident on the first glass plate 11 at an incident angle of 60°, the transmission characteristic S21 is preferably −3.0 [dB] or more, more preferably −2.5 [dB] or more, even more preferably −2.0 [dB] or more, and particularly preferably −1.8 [dB] or more.

[0053] Further, the upper limit of the transmission characteristic S21 under the above conditions is not particularly limited, but is, for example, −0.50 [dB] or less.

[0054] In addition, in the laminated glass for vehicles 10 according to this embodiment, the transmission characteristic S21 when a TM wave having a frequency of 79 [GHz] is incident on the first glass plate 11 at an incident angle of 67.5° is preferably −3.1 [dB] or more.

[0055] Furthermore, in the laminated glass 10 for vehicles, when a TM wave having a frequency of 79 [GHz] is incident on the first glass plate 11 at an incident angle of 67.5°, the transmission characteristic S21 is more preferably −2.5 [dB] or more, even more preferably −2.0 [dB] or more, and particularly preferably −1.8 [dB] or more.

[0056] Furthermore, the upper limit of the transmission characteristic S21 under the above conditions is not particularly limited, but is, for example, −0.50 [dB] or less.

[0057] The laminated glass 10 for vehicles according to this embodiment preferably has a transmission characteristic S21 of −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident on the first glass plate 11 at an incident angle of 20°.

[0058] In addition, in the laminated glass 10 for vehicles, when a TM wave having a frequency of 79 [GHz] is incident on the first glass plate 11 at an incident angle of 20°, the transmission characteristic S21 is preferably −3.0 [dB] or more, more preferably −2.5 [dB] or more, even more preferably −2.0 [dB] or more, and particularly preferably −1.8 [dB] or more.

[0059] Furthermore, the upper limit of the transmission characteristic S21 under the above conditions is not particularly limited, but is, for example, −0.50 [dB] or less.

[0060] Furthermore, the laminated glass 10 for vehicles according to this embodiment preferably has a transmission characteristic S21 of −4.0 dB or more when a TM wave having a frequency of 79 GHz is incident on the first glass plate 11 at an incident angle of 45°.

[0061] In addition, in the laminated glass 10 for vehicles, when a TM wave having a frequency of 79 [GHz] is incident on the first glass plate 11 at an incident angle of 20°, the transmission characteristic S21 is preferably −3.0 [dB] or more, more preferably −2.5 [dB] or more, even more preferably −2.0 [dB] or more, and particularly preferably −1.8 [dB] or more.

[0062] Furthermore, the upper limit of the transmission characteristic S21 under the above conditions is not particularly limited, but is, for example, −0.50 [dB] or less.

[0063] In addition, in the laminated glass for vehicles 10 according to this embodiment, the transmission characteristic S21 of a TM wave having a frequency of 28 [GHz] incident on the first glass sheet 11 is also useful as an index of the millimeter wave transmittance of the window glass of an automobile. Note that this evaluation is also performed under the condition that the direction of the main lobe in wireless communication at a frequency of 28 [GHz] travels in a direction parallel to the horizontal plane.

[0064] In the laminated glass 10 for vehicles according to this embodiment, the transmission characteristic S21 when a TM wave having a frequency of 28 [GHz] is incident on the first glass plate 11 at an incident angle of 0° to 70° is preferably −2.0 [dB] or more.

[0065] Furthermore, in the laminated glass 10 for vehicles, when a TM wave having a frequency of 28 [GHz] is incident on the first glass plate 11 at an incident angle of 0° to 70°, the transmission characteristic S21 is more preferably −1.5 [dB] or more, even more preferably −1.0 [dB] or more, and particularly preferably −0.70 [dB] or more.

[0066] Furthermore, the upper limit of the transmission characteristic S21 under the above conditions is not particularly limited, but is, for example, −0.30 [dB] or less.

[0067] In addition, in the laminated glass for vehicles 10 according to this embodiment, the transmission characteristic S21 when a TM wave having a frequency of 28 GHz is incident on the first glass plate 11 at an incident angle of 67.5° is preferably −0.28 dB or more.

[0068] Furthermore, in the laminated glass 10 for vehicles, when a TM wave having a frequency of 28 GHz is incident on the first glass plate 11 at an incident angle of 67.5°, the transmission characteristic S21 is preferably −0.24 dB or more, and more preferably −0.20 dB or more.

[0069] Furthermore, the upper limit of the transmission characteristic S21 under the above conditions is not particularly limited, but is, for example, −0.10 [dB] or less.

[0070] Furthermore, because the first glass plate 11 is made of borosilicate glass, the laminated glass 10 has high strength against external impacts. The strength of the laminated glass 10 can be evaluated, for example, by an impact resistance test shown in Figure 2(A).

[0071] Specifically, under the following measurement condition 1, pin P is collided with a sample laminated glass at an impact speed V of 40 km / h and an impact angle β of 90°, as shown in Figure 2(A). The strength of the laminated glass can be evaluated by determining whether a crack of 5.0 mm or longer occurs in the laminated glass. If no crack of 5.0 mm or longer occurs, the strength of the laminated glass can be evaluated as high.

[0072] Here, the length of the crack refers to the maximum length of the straight-line distance in the horizontal direction from the start point to the end point of the crack, when the crack occurs perpendicular to the thickness direction of the glass, i.e., in the horizontal direction of the dent caused by the collision, as shown in Figure 2 (B), with the center of the dent (point of impact) as the start point and the tip of the crack as the end point.

[0073] <Measurement condition 1> ·Collision speed V: 40 [km / h] ·Collision angle β:90[°] Pin: Carbide pin Pin weight: 1.2g Pin tip angle: 90° Pin tip radius: 0.2 mm Planar size of laminated glass sample: 300mm x 300mm Number of replicate tests: 10

[0074] Alternatively, evaluation can be performed by impacting a pin against the laminated glass under the following measurement condition 2, and measuring the impact speed V [km / h] of the pin when a crack of 5.0 [mm] in length occurs in the laminated glass.

[0075] <Measurement condition 2> ·Collision speed V: 40, 60 [km / h] ·Collision angle β:90[°] Pin: Carbide pin Pin weight: 1.2g Pin tip angle: 90° Pin tip radius: 0.2 mm Planar size of laminated glass sample: 300mm x 300mm Number of replicate tests: 10

[0076] Here, there is a linear relationship between the impact speed V and the crack length. Therefore, by measuring the crack length at an impact speed V of 40 [km / h] and the crack length at an impact speed V of 60 [km / h], it is possible to calculate the pin impact speed V [km / h] at which the crack length becomes 5.0 [mm].

[0077] In the laminated glass for vehicles 10 according to this embodiment, the impact speed V at which a crack length of 5.0 mm is measured in the impact resistance test is preferably 45 km / h or more, more preferably 50 km / h or more, and even more preferably 55 km / h or more. If the impact speed V is 45 km / h or more, high strength can be achieved against external impacts such as flying stones while driving.

[0078] Hereinafter, each of the components constituting the laminated glass for vehicles 10 according to this embodiment will be described in detail.

[0079] [First glass plate, second glass plate] The first glass plate 11 is made of borosilicate glass containing 1.0% or more B2O3 in terms of mole percentage based on oxides. As described above, borosilicate glass has high strength and excellent millimeter wave transmittance.

[0080] Preferably, both the first glass plate 11 and the second glass plate 12 are made of the above borosilicate glass. More preferably, the first glass plate 11 and the second glass plate 12 are made of borosilicate glass having the same composition.

[0081] From the viewpoint of improving the strength against chipping stones and improving millimeter wave transmittance by realizing a low dielectric constant and a low dielectric loss tangent, the borosilicate glass in this embodiment preferably contains 2.0% or more, more preferably 5.0% or more, and even more preferably 7.0% or more of B2O3 expressed as mole percentage on an oxide basis.

[0082] Furthermore, if the borosilicate glass contains too much B2O3, the acid resistance and alkali resistance may decrease, and in the case of an alkali-containing composition, the alkali element may be more likely to volatilize during melting and molding, which may result in a deterioration in glass quality. Therefore, borosilicate glass should contain 22% or less of B2O3, preferably 20% or less, and more preferably 15% or less.

[0083] The borosilicate glass in this embodiment preferably contains a small amount of alkali components (that is, oxides of alkali metals such as lithium, sodium, and potassium) from the viewpoint of improving millimeter wave transmittance.

[0084] For example, borosilicate glass preferably contains 10% or less of alkali components in total, expressed as mole percentage on an oxide basis, more preferably 7.0% or less, even more preferably 5.0% or less, particularly preferably 4.0% or less, and most preferably 3.0% or less. Also, borosilicate glass with a total alkali content of 0.10% or less (alkali-free glass) can be preferably used.

[0085] In the borosilicate glass of the present embodiment, the contents of the alkali components and components other than B2O3 are not particularly limited. For example, the contents of the respective components expressed as mole percentages based on oxides are as follows: 50%≦SiO2≦90% 0%≦Al2O3≦20% 0%≦MgO≦15% 0%≦CaO≦15% 0%≦SrO≦10% 0%≦BaO≦10% 0%≦RO≦25% (RO represents the total amount of MgO, CaO, SrO, and BaO) It is preferable to satisfy the following.

[0086] Furthermore, as the borosilicate glass in this embodiment, for example, glasses having the following compositions (hereinafter also referred to as "composition A," "composition B," and "composition C") can be used. Details of the glass of composition A and the glass of composition B (composition C) will be described below.

[0087] (Glass of composition A) The glass of composition A is a glass in which the content of each component expressed as a mole percentage based on oxide satisfies the following relationship: 80%≦SiO2+Al2O3+B2O3≦98% 60%≦SiO2≦90% 0%≦Al2O3≦10% 1.0%≦B2O3≦25% 1.0%≦R2O≦10% 0%≦RO≦9.0% 0≦Li2O / R2O≦1.0 0≦Na2O / R2O≦0.90 0≦K2O / R2O≦0.70 (RO represents the total amount of LiO, NaO, and KO, and RO represents the total amount of MgO, CaO, SrO, and BaO.) The glass of composition A will be described in detail below.

[0088] The specific gravity of the glass of composition A is preferably 2.0 or more and 2.5 or less. The Young's modulus of the glass of composition A is preferably 50 GPa or more and 80 GPa or less. The average linear expansion coefficient of the glass of composition A from 50°C to 350°C is 25×10 -7 / K or higher, 90×10 -7 / K or less. If the glass of composition A satisfies these conditions, it can be suitably used as laminated glass for vehicles.

[0089] The glass of composition A preferably contains a certain amount of SiO2 or more to ensure weather resistance, and as a result, the specific gravity of the glass of composition A can be 2.0 or more. The specific gravity of the glass of composition A is preferably 2.1 or more.

[0090] Furthermore, if the specific gravity of the glass of composition A is 2.5 or less, the glass is less likely to become brittle and is lightweight. The specific gravity of the glass of composition A is preferably 2.4 or less.

[0091] The glass of composition A has a high Young's modulus and therefore has high rigidity, making it more suitable for use as window glass for automobiles, etc. The Young's modulus of the glass of composition A is preferably 55 GPa or more, more preferably 60 GPa or more, and even more preferably 62 GPa or more.

[0092] On the other hand, increasing the amount of Al2O3 or MgO to increase the Young's modulus increases the dielectric constant and dielectric loss tangent of the glass, so the appropriate Young's modulus for glass of composition A is 75 GPa or less, preferably 70 GPa or less, and more preferably 68 GPa or less.

[0093] Furthermore, the glass of composition A is preferable because the small average linear expansion coefficient suppresses the generation of thermal stress due to the temperature distribution in the glass plate, making the glass plate less susceptible to thermal cracking.

[0094] The average linear expansion coefficient of the glass of composition A from 50°C to 350°C is preferably 20 × 10 -7 / K or more, more preferably 25×10 -7 / K or more, and more preferably 28×10 -7 / K or higher.

[0095] On the other hand, if the average linear expansion coefficient of the glass of composition A becomes too large, thermal stress due to the temperature distribution in the glass sheet is likely to occur during the glass sheet forming process, annealing process, or windshield forming process, which may result in thermal cracking of the glass sheet. Also, if the average linear expansion coefficient of the glass of composition A becomes too large, the difference in expansion between the glass sheet and supporting members, etc., becomes large, which may cause distortion and lead to cracking of the glass sheet.

[0096] The average linear expansion coefficient of glass of composition A from 50 to 350°C is 45 × 10 -7 / K or less is preferable, and 40×10 -7 / K or less, and more preferably 38×10 -7 / K or less, and more preferably 36×10 -7 / K or less, and particularly preferably 34×10 -7 / K or less, and most preferably 32×10 -7 / K or less.

[0097] In addition, in the glass of composition A, T2 is preferably 1900°C or less. In addition, in the glass of composition A, T4 is preferably 1350°C or less, and T4-T Lis preferably -50°C or higher.

[0098] In this specification, T2 is the glass viscosity of 10 2 (dPa·s), and T4 is the temperature at which the glass viscosity is 10 4 (dPa s), and T L represents the liquidus temperature of the glass.

[0099] When T2 or T4 of the glass of composition A exceeds these predetermined temperatures, it becomes difficult to produce large glass plates by the float method, roll-out method, down-draw method or the like.

[0100] The glass of composition A preferably has a T2 of 1850°C or less, more preferably 1800°C or less.

[0101] The glass of composition A has a T4 of more preferably 1300°C or less, and further preferably 1250°C or less.

[0102] There are no particular lower limits for T2 and T4 of the glass of composition A, but in order to maintain weather resistance and glass specific gravity, T2 is typically 1200°C or higher and T4 is typically 800°C or higher.

[0103] The T2 of the glass of composition A is preferably 1300°C or higher, more preferably 1400°C or higher.

[0104] The T4 of the glass of composition A is preferably 900°C or higher, more preferably 1000°C or higher.

[0105] Furthermore, in order to enable production by the float process, T4-T of glass of composition A was L is preferably −50° C. or more. If this difference is less than −50° C., devitrification occurs in the glass during glass molding, causing problems such as a decrease in the mechanical properties and transparency of the glass, making it difficult to obtain high-quality glass.

[0106] T4-T of glass of composition A Lis more preferably 0°C or higher, and further preferably +20°C or higher.

[0107] In addition, the glass of composition A is T g It is preferable that the temperature is 400°C or higher and 650°C or lower. g represents the glass transition temperature of the glass. g If the temperature is within this specified range, the glass can be bent within the normal manufacturing conditions. g If the T is lower than 400°C, there will be no problem with formability, but the alkali content or alkaline earth content will be too high, which will tend to cause problems such as excessive thermal expansion of the glass and reduced weather resistance. g If the temperature is lower than 400°C, the glass may devitrify in the forming temperature range and become unable to be formed.

[0108] T of glass of composition A g is more preferably 450°C or higher, further preferably 470°C or higher, and particularly preferably 490°C or higher.

[0109] On the other hand, T g If T is too high, high temperatures are required during glass bending, making manufacturing difficult. g The temperature is more preferably 600°C or lower, and further preferably 550°C or lower.

[0110] Furthermore, glass with composition A can have a low tan δ by adjusting the composition, which reduces dielectric loss and enables high millimeter-wave transmittance. Similarly, glass with composition A can have its relative permittivity adjusted by adjusting the composition, which suppresses radio wave reflection at the interface with the interlayer film and enables high millimeter-wave transmittance.

[0111] Furthermore, the relative dielectric constant at 10 GHz of the glass of composition A is preferably 6.00 or less. If the relative dielectric constant at 10 GHz is 6.00 or less, the difference in relative dielectric constant with the interlayer film becomes small, and reflection of radio waves at the interface with the interlayer film can be suppressed.

[0112] The relative dielectric constant at 10 GHz of the glass of composition A is more preferably 5.50 or less, further preferably 5.00 or less, further preferably 4.75 or less, particularly preferably 4.50 or less, and most preferably 4.40 or less.

[0113] The lower limit of the relative dielectric constant at 10 GHz of the glass of composition A is not particularly limited, but is, for example, 3.80 or more.

[0114] Furthermore, the dielectric loss tangent at 10 GHz of the glass of composition A is preferably 0.010 or less. If the dielectric loss tangent at 10 GHz is 0.010 or less, radio wave transmittance can be increased.

[0115] The dielectric loss tangent at 10 GHz of the glass of composition A is more preferably 0.0090 or less, further preferably 0.0085 or less, further preferably 0.0080 or less, particularly preferably 0.0075 or less, and most preferably 0.0070 or less.

[0116] The lower limit of the dielectric loss tangent at 10 GHz of the glass of composition A is not particularly limited, but is, for example, 0.0030 or more.

[0117] If the relative permittivity and dielectric loss tangent of the glass at 10 GHz satisfy the above ranges, high millimeter wave transmittance can be achieved even at 10 to 90 GHz.

[0118] The dielectric constant and dielectric loss tangent of glass at 10 GHz can be measured, for example, by the split post dielectric resonator method (SPDR method) using a QWED split post dielectric resonator with a nominal fundamental frequency of 10 GHz, a Keysight E8361C vector network analyzer, and Keysight 85071E Option 300 dielectric constant calculation software.

[0119] Furthermore, the glass of composition A has an SiO2 content of 60% or more and 90% or less, expressed as mole percentage based on oxides.

[0120] Furthermore, the glass of composition A has an Al2O3 content of 0% or more and 10% or less.

[0121] The SiO2 and Al2O3 in the glass of composition A contribute to improving the Young's modulus, making it easier to ensure the strength required for automotive applications, architectural applications, etc. If the glass of composition A contains too little Al2O3 and / or SiO2, it becomes difficult to ensure weather resistance, and the average linear expansion coefficient becomes too large, which may cause the glass sheet to crack due to heat. If the glass of composition A contains too much Al2O3 and / or SiO2, the viscosity of the glass during melting may increase, making glass manufacturing difficult. Furthermore, if the glass of composition A contains too much Al2O3, the millimeter wave transmittance may also decrease.

[0122] The SiO2 content of the glass of composition A is preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more.

[0123] The SiO2 content of the glass of composition A is preferably 88% or less, more preferably 86% or less, even more preferably 84% or less, and particularly preferably 82% or less.

[0124] The Al2O3 content in the glass of composition A is preferably 0.10% or more, more preferably 0.50% or more, and even more preferably 1.0% or more, in order to suppress phase separation of the glass and improve weather resistance.

[0125] The Al2O3 content in the glass of composition A is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less, from the viewpoints of keeping T2 low to facilitate glass production and of increasing millimeter wave transmittance.

[0126] The B2O3 content in the glass of composition A may be 1.0% or more and 25% or less. As mentioned above, B2O3 is added to improve the glass strength and millimeter wave transmittance, and also contributes to improving the meltability.

[0127] The B2O3 content of the glass of composition A is preferably 5.0% or more, more preferably 7.0% or more, and even more preferably 9.0% or more.

[0128] On the other hand, if the B2O3 content in the glass of composition A is too high, alkali elements tend to volatilize during melting and molding, which may result in a deterioration in glass quality. Also, if the B2O3 content in the glass of composition A is too high, the acid resistance and alkali resistance may decrease. The B2O3 content in the glass of composition A is preferably 20% or less, more preferably 15% or less, even more preferably 13% or less, and particularly preferably 11% or less.

[0129] In order to improve millimeter wave transmittance, the total of SiO2+Al2O3+B2O3, that is, the total content of SiO2, Al2O3 and B2O3 in the glass of composition A, should be 80% or more and 98% or less.

[0130] Furthermore, in order to keep the temperatures T2 and T4 of the glass of composition A low and to facilitate the production of the glass, SiO2+Al2O3+B2O3 is preferably 97% or less, and more preferably 96% or less.

[0131] However, if the glass of composition A contains too little SiO2+Al2O3+B2O3, the weather resistance may decrease and the relative dielectric constant and dielectric loss tangent may become too large. Therefore, the SiO2+Al2O3+B2O3 content of the glass of composition A is preferably 85% or more, and more preferably 90% or more.

[0132] The content of MgO in the glass of composition A may be set to 0% or more and 9.0% or less. MgO is a component that promotes the melting of glass raw materials and improves weather resistance and Young's modulus.

[0133] The glass of composition A may contain MgO, and when it does, the content is preferably 0.10% or more, more preferably 0.50% or more, and even more preferably 1.0% or more.

[0134] If the glass of composition A has an MgO content of 9.0% or less, it is less susceptible to devitrification and can suppress increases in the relative dielectric constant and dielectric loss tangent. The MgO content of the glass of composition A is preferably 8.0% or less, more preferably 6.0% or less, even more preferably 4.0% or less, particularly preferably 3.0% or less, and most preferably 2.0% or less.

[0135] The glass of composition A may contain certain amounts of CaO, SrO, and / or BaO to improve the meltability of the glass raw materials. The CaO content may be 0% or more and 9.0% or less. The SrO content of the glass of composition A may be 0% or more and 3.0% or less. The BaO content of the glass of composition A may be 0% or more and 3.0% or less.

[0136] In the glass of composition A, the content of CaO, SrO, and / or BaO, if present, is preferably 0.10% or more, more preferably 0.50% or more, and even more preferably 1.0% or more, which improves the meltability and formability of the glass raw materials (reduction in T2 and T4).

[0137] In the glass of composition A, by limiting the CaO content to 9.0% or less, the SrO content to 3.0% or less, and the BaO content to 3.0% or less, an increase in the specific gravity of the glass is avoided and low brittleness and strength are maintained.

[0138] In order to prevent the glass from becoming brittle and to prevent an increase in the relative dielectric constant and dielectric loss tangent of the glass, the CaO content in the glass of composition A is preferably 8.0% or less, more preferably 6.0% or less, even more preferably 4.0% or less, particularly preferably 3.0% or less, and most preferably 2.0% or less.

[0139] The SrO content in the glass of composition A is more preferably 2.0% or less, further preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably substantially zero.

[0140] The BaO content in the glass of composition A is more preferably 2.0% or less, further preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably substantially no BaO is contained.

[0141] The expression "substantially free of" a certain component in glass means that the component is not actively added, except in cases where it is unavoidably mixed in as an impurity.

[0142] In this specification, "RO" represents the total content of MgO, CaO, SrO, and BaO. The glass of composition A has an RO content of 0% or more and 9.0% or less. If the RO content of the glass of composition A is 9.0% or less, the weather resistance is improved and increases in the relative dielectric constant and dielectric loss tangent can be suppressed.

[0143] The RO in the glass of composition A is preferably 8.0% or less, more preferably 6.0% or less, even more preferably 4.0% or less, particularly preferably 3.0% or less, and most preferably 2.0% or less.

[0144] Furthermore, from the viewpoint of lowering the temperatures T2 and T4 during production or from the viewpoint of increasing the Young's modulus, the glass of composition A may contain RO. When the glass of composition A contains RO, the RO content is preferably 0.10% or more, more preferably 0.50% or more, and particularly preferably 1.0% or more.

[0145] The Li2O content in the glass of composition A may be 0% or more and 10% or less. Li2O is a component that improves the meltability of the glass, and also contributes to increasing the Young's modulus and improving the strength of the glass. By including Li2O in the glass of composition A, the viscosity of the glass decreases, improving the formability of the windshield.

[0146] When Li2O is contained in the glass of composition A, the content may be 0.10% or more, preferably 1.0% or more, more preferably 2.0% or more, and even more preferably 3.0% or more.

[0147] On the other hand, if the glass of composition A contains too much Li2O, devitrification or phase separation may occur during glass production, making production difficult. Furthermore, if the glass of composition A contains too much Li2O, it may increase raw material costs and cause increases in the relative permittivity and dielectric loss tangent. Therefore, the Li2O content in the glass of composition A is preferably 8.0% or less, more preferably 7.0% or less, even more preferably 6.0% or less, and particularly preferably 5.0% or less.

[0148] The content of Na2O in the glass of composition A may be 0% or more and 10% or less. Na2O is a component that improves the meltability of the glass, and it is more preferable to include 0.10% or more of either or both. This makes it easier to keep the T2 of the glass of composition A at 1900°C or less and the T4 at 1350°C or less. Furthermore, by including Na2O in the glass of composition A, the viscosity of the glass is reduced, thereby improving the formability of the windshield.

[0149] The Na2O content in the glass of composition A is preferably 0.50% or more, more preferably 1.0% or more, and even more preferably 2.0% or more.

[0150] On the other hand, if the glass of composition A contains too much Na2O, it not only increases the relative permittivity and dielectric loss tangent, but also makes the average linear expansion coefficient too large, making the glass sheet more susceptible to thermal cracking. The Na2O content of the glass of composition A is preferably 8.0% or less, more preferably 6.0% or less, even more preferably 4.0% or less, and most preferably 3.0% or less.

[0151] The content of K2O in the glass of composition A may be 0% or more and 10% or less. In the glass of composition A, K2O is a component that improves the melting property of the glass, and it is preferable that the content of K2O be 0.10% or more. This makes it easier to keep the T2 of the glass of composition A at 1900°C or less and the T4 at 1350°C or less.

[0152] The K2O content in the glass of composition A is more preferably 0.30% or more, and even more preferably 0.60% or more.

[0153] On the other hand, if the K2O content in the glass of composition A is too high, it will cause an increase in the relative dielectric constant and dielectric loss tangent, and will also cause the average linear expansion coefficient to become too large, making the glass sheet more susceptible to thermal cracking. The K2O content in the glass of composition A is preferably 8.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, particularly preferably 2.0% or less, and most preferably 1.0% or less.

[0154] The glass of composition A is more preferable because it can improve weather resistance while maintaining solubility by containing all of Li2O, Na2O, and K2O, and can also be expected to have the effect of increasing millimeter wave transmittance.

[0155] In glass of composition A, if the content of Li2O, Na2O, and / or K2O is low, the viscosity of the glass increases, which may make it impossible to form a windshield. By adjusting the content of Li2O, Na2O, and / or K2O to the above-mentioned specified amounts, glass of composition A can be used as a window material that also has good compatibility with other components. Furthermore, by adjusting the content of Li2O, Na2O, and / or K2O to the above-mentioned ranges, glass of composition A can achieve high millimeter-wave transmittance.

[0156] In this specification, "R2O" represents the total amount of alkali metal oxides. This usually means the sum of the contents of Li2O, Na2O, and K2O. The R2O content of the glass of composition A is 1.0% or more and 10% or less. If the R2O content of the glass of composition A is 10% or less, the weather resistance is improved.

[0157] The R2O content of the glass of composition A is preferably 8.0% or less, more preferably 7.0% or less, even more preferably 6.0% or less, and particularly preferably 5.0% or less.

[0158] Furthermore, from the viewpoint of lowering temperatures T2 and T4 during production or for facilitating heating by direct application of electricity to the glass melt, it is preferable for the glass to contain a trace amount of R2O. The R2O content in the glass of composition A is preferably 1.0% or more, more preferably 2.0% or more, even more preferably 3.0% or more, and particularly preferably 4.0% or more.

[0159] In order to improve weather resistance and millimeter wave transmittance, the Na2O / R2O ratio in the glass of composition A is set to between 0 and 0.90. If the Na2O / R2O ratio in the glass of composition A is too small or too large, the effects of improving weather resistance and millimeter wave transmittance may not be fully achieved.

[0160] When Li2O is contained, the lower limit of Na2O / R2O in the glass of composition A is preferably 0.010 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more.

[0161] Furthermore, when the glass of composition A does not contain Li2O, the lower limit of Na2O / R2O should be slightly larger than when Li2O is contained, and is preferably 0.010 or more, more preferably 0.20 or more, and even more preferably 0.40 or more.

[0162] In the glass of composition A, when Li2O is contained, the upper limit of Na2O / R2O is preferably 0.80 or less, more preferably 0.60 or less, and even more preferably 0.40 or less.

[0163] Furthermore, when the glass of composition A does not contain Li2O, the upper limit of Na2O / R2O should be slightly larger than when Li2O is contained, and is preferably 0.90 or less, more preferably 0.70 or less, and even more preferably 0.55 or less.

[0164] The K2O / R2O ratio in the glass of composition A is set to 0 or more and 0.70 or less in order to improve weather resistance and millimeter wave transmittance. If the K2O / R2O ratio is too small or too large, the effect of improving millimeter wave transmittance may not be fully achieved.

[0165] When Li2O is contained, the lower limit of K2O / R2O in the glass of composition A is preferably 0.010 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more.

[0166] Furthermore, when the glass of composition A does not contain Li2O, the lower limit of K2O / R2O is preferably slightly larger than when Li2O is contained, and is preferably 0.010 or more, more preferably 0.20 or more, and even more preferably 0.40 or more.

[0167] In the glass of composition A, when Li2O is contained, the upper limit of K2O / R2O is preferably 0.70 or less, more preferably 0.60 or less, and even more preferably 0.40 or less.

[0168] Furthermore, when the glass of composition A does not contain Li2O, the upper limit of K2O / R2O should be slightly larger than when Li2O is contained, and is preferably 0.70 or less, and more preferably 0.60 or less.

[0169] In the glass of composition A, the Li2O / R2O ratio may be set to 0 or more and 1.0 or less in order to improve weather resistance and millimeter wave transmittance. Li2O has the effect of improving millimeter wave transmittance compared to Na2O and K2O, and from the viewpoint of this effect, a larger Li2O / R2O ratio is preferable.

[0170] When Na2O and / or K2O is contained in the glass of composition A, the lower limit of Li2O / R2O is preferably 0.010 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more.

[0171] Furthermore, the upper limit of Li2O / R2O in the glass of composition A is preferably 1.0 or less, more preferably 0.90 or less, and even more preferably 0.80 or less, from the viewpoint of improving weather resistance and suppressing phase separation.

[0172] The content of Fe2O3 in the glass of composition A may be 0.0010% or more and 1.0% or less. If the content of Fe2O3 in the glass of composition A is less than 0.0010%, it may not be usable for applications requiring heat insulation. Furthermore, it may be necessary to use expensive raw materials with low iron content to manufacture glass sheets. Furthermore, if the content of Fe2O3 in the glass of composition A is less than 0.0010%, there is a risk that more heat radiation than necessary will reach the bottom of the melting furnace during glass melting, placing a strain on the melting furnace.

[0173] The content of Fe2O3 in the glass of composition A is preferably 0.0030% or more, more preferably 0.010% or more, even more preferably 0.050% or more, and particularly preferably 0.10% or more.

[0174] On the other hand, if the Fe2O3 content in the glass of composition A exceeds 1.0%, heat transfer by radiation may be hindered during production, making it difficult for the raw materials to melt. Furthermore, if the Fe2O3 content in the glass of composition A is too high, the light transmittance in the visible range may decrease, making the glass unsuitable for use as window glass for automobiles.

[0175] The content of Fe2O3 in the glass of composition A is preferably 0.50% or less, more preferably 0.30% or less, and even more preferably 0.20% or less.

[0176] Furthermore, the glass of composition A may contain TiO2. If it does contain TiO2, the content should be 0.0010% or more and 5.0% or less. For example, if the glass of composition A does not contain TiO2, a bubble layer may form on the surface of the molten glass during the production of glass sheets. This prevents the temperature of the molten glass from rising, making it difficult to refine, and reducing productivity. Therefore, in order to thin or eliminate the bubble layer formed on the surface of the molten glass, a titanium compound may be supplied as an antifoaming agent to the bubble layer formed on the surface of the molten glass. The titanium compound is incorporated into the molten glass and exists as TiO2.

[0177] The TiO2 content of the glass in composition A is preferably 0.0050% or more. In addition, TiO2 has an absorption property in the ultraviolet region, so it is preferable to add it when it is desired to cut ultraviolet light. In this case, the TiO2 content may be preferably 0.050% or more, and may further be 0.10% or more.

[0178] On the other hand, if the TiO2 content is too high, the liquidus temperature may rise, which may cause devitrification. Furthermore, the TiO2 content may absorb light in the visible range, resulting in yellow coloration. Therefore, the TiO2 content in the glass of composition A is preferably 5.0% or less, more preferably 0.50% or less, even more preferably 0.20% or less, and particularly preferably 0.10% or less.

[0179] When water is present in the glass of composition A, the glass absorbs light in the near-infrared region, reducing the transmittance of light in that region. This can cause problems when transmitting and receiving millimeter-wave radio waves and when using infrared emitting devices (such as laser radar).

[0180] The water content in glass can generally be expressed as the β-OH value. The β-OH value of glass with composition A is 0.70 mm -1 Preferably less than 0.60mm -1 Less than 0.50mm is more preferable -1 Less than 0.40 mm is more preferable. -1The following is particularly preferred: β-OH is obtained from the transmittance of the glass measured using an FT-IR (Fourier transform infrared spectrophotometer) by the following formula:

[0181] 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 wave number 3600cm -1 Minimum transmittance in the vicinity [%]

[0182] As mentioned above, glass of composition A absorbs light in the near-infrared region when water is present in the glass. Therefore, in order to improve the heat insulation properties, the β-OH value of composition A is set to 0.050 mm. -1 More than 0.10mm is preferable. -1 More preferably, 0.15 mm or more -1 The above is even more preferable.

[0183] (Glass of composition B and composition C) Glass with composition B has a total content of SiO2, B2O3, and Al2O3 of 72% or more, expressed as mole percentages based on the oxides of each component. Using glass with composition B makes it easier to ensure glass strength, and is particularly preferable because it increases resistance to chipping caused by flying stones. Furthermore, using composition B is preferable because it maintains high millimeter wave transmittance.

[0184] Furthermore, as the glass of composition B, a glass (also referred to as "composition C") in which the content of each component expressed as mole percentage based on oxide satisfies the following relationship is more preferable. 72%≦SiO2+Al2O3+B2O3≦98% 55%≦SiO2≦80% 0%≦Al2O3≦20% 1.0%≦B2O3≦25% 0%≦R2O≦5.0% 0%≦RO≦25% (RO represents the total amount of LiO, NaO, and KO, and RO represents the total amount of MgO, CaO, SrO, and BaO.) A more preferable composition range for the glass of composition C will be explained in detail below.

[0185] As described above, the glass of composition C has a content of SiO2+Al2O3+B2O3 of 72% or more and 98% or less.

[0186] If the SiO2+Al2O3+B2O3 content of glass with composition C is less than 72%, the network components that make up the glass will be reduced, making the glass more susceptible to cracks. Furthermore, the cracks that do occur may be more likely to extend over a longer distance, and millimeter-wave transmittance may also be reduced.

[0187] The content of SiO2+Al2O3+B2O3 in the glass of composition C is preferably 74% or more, more preferably 76% or more, even more preferably 78% or more, particularly preferably 80% or more, and most preferably 82% or more.

[0188] On the other hand, if the glass of composition C has too much network component, the temperatures for melting the glass and for forming the glass become too high, which may make it difficult to manufacture a glass sheet. Therefore, the content of SiO2 + Al2O3 + B2O3 in the glass of composition C is preferably 97% or less, more preferably 94% or less, even more preferably 90% or less, and particularly preferably 88% or less.

[0189] The SiO2 content in the glass of composition C is preferably 55% or more from the viewpoints of improving millimeter wave transmittance, suppressing cracking in the glass, and making it difficult for cracks that do occur to extend in distance. The SiO2 content in the glass of composition C is more preferably 57% or more, even more preferably 59% or more, particularly preferably 61% or more, and most preferably 63% or more.

[0190] On the other hand, if the SiO2 content in the glass of composition C is too high, the temperatures for melting the glass and for forming the glass become too high, which may make it difficult to manufacture a glass plate. Therefore, the SiO2 content in the glass of composition C is preferably 80% or less, more preferably 75% or less, even more preferably 70% or less, particularly preferably 68% or less, and most preferably 66% or less.

[0191] The glass of composition C may contain Al2O3 to improve Young's modulus and weather resistance. The Al2O3 content in the glass of composition C is preferably 5.0% or more, more preferably 6.0% or more, even more preferably 7.0% or more, particularly preferably 8.0% or more, and most preferably 10% or more.

[0192] On the other hand, if the Al2O3 content in the glass of composition C is too high, the viscosity during glass melting may increase, making glass production difficult, the relative permittivity and dielectric loss tangent may increase, reducing millimeter wave transmittance, and devitrification may occur. Therefore, the Al2O3 content in the glass of composition C may be 20% or less, preferably 18% or less, more preferably 16% or less, even more preferably 14% or less, particularly preferably 13% or less, and most preferably 12% or less.

[0193] As mentioned above, B2O3 is added to the glass of composition C to improve meltability, improve the glass's anti-stone strength, and increase millimeter wave transmittance. The B2O3 content of the glass of composition C is 1.0% or more and 25% or less.

[0194] On the other hand, if the B2O3 content in the glass of composition C is too high, components in the glass tend to volatilize during melting and molding, which may result in a deterioration in the quality of the glass. Therefore, the B2O3 content in the glass of composition C is preferably 23% or less, more preferably 21% or less, even more preferably 19% or less, still more preferably 17% or less, still more preferably 15% or less, particularly preferably 13% or less, and most preferably 11% or less.

[0195] The content of B2O3 in the glass of composition C is preferably 2.0% or more, more preferably 4.0% or more, even more preferably 5.0% or more, particularly preferably 6.0% or more, and most preferably 7.0% or more.

[0196] In order to improve the millimeter wave transmittance, the SiO2+Al2O3 content of the glass of composition C, ie, the total of the SiO2 content and the Al2O3 content, is 65% or more and 85% or less.

[0197] To increase millimeter wave transmittance and to further consider keeping temperatures T2 and T4 low to facilitate glass production, the SiO2 + Al2O3 content is preferably as low as possible, with 84% or less being preferred. In the glass of composition C, the SiO2 + Al2O3 content is more preferably 83% or less, even more preferably 82% or less, still more preferably 81% or less, particularly preferably 80% or less, and most preferably 79% or less.

[0198] However, if the content of SiO2+Al2O3 in the glass of composition C is too low, the Young's modulus and weather resistance may decrease, and the average linear expansion coefficient may become too large. Therefore, the content of SiO2+Al2O3 in the glass of composition C is preferably 68% or more, more preferably 69% or more, even more preferably 70% or more, still more preferably 72% or more, particularly preferably 74% or more, and most preferably 75% or more.

[0199] The glass of composition C preferably has an Al2O3 / B2O3 ratio of 7.0 or less. When the Al2O3 / B2O3 ratio in the glass of composition C is 7.0 or less, millimeter wave transmittance can be further increased, which is preferable. Furthermore, when the Al2O3 / B2O3 ratio in the glass of composition C is 7.0 or less, the glass is more easily melted, which reduces the viscosity of the glass during production and makes it easier to keep T2 at 1750°C or less and T4 at 1350°C or less.

[0200] The value of Al2O3 / B2O3 in the glass of composition C is preferably 6.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 2.0 or less.

[0201] From the viewpoint of improving acid resistance and alkali resistance, the Al2O3 / B2O3 value in the glass of composition C is preferably 0.10 or more, more preferably 0.50 or more, even more preferably 0.80 or more, still more preferably 1.0 or more, particularly preferably 1.3 or more, and most preferably 1.4 or more.

[0202] The glass of composition C may contain a small amount of R2O from the viewpoint of lowering the temperatures T2 and T4 during production or to facilitate heating by directly passing current through the glass melt. The inclusion of R2O in the glass of composition C reduces the viscosity of the glass, improving the formability of the windshield. In this case, the R2O content of the glass of composition C is preferably 0.0010% or more, more preferably 0.0050% or more, even more preferably 0.0070% or more, still more preferably 0.010% or more, particularly preferably 0.020% or more, and most preferably 0.030% or more.

[0203] On the other hand, in the glass of composition C, if the R2O content is too high, the millimeter wave transmittance may decrease. Therefore, the R2O content should be 5.0% or less, preferably 2.0% or less, more preferably 1.5% or less, even more preferably 1.0% or less, still more preferably 0.50% or less, particularly preferably 0.20% or less, and most preferably 0.10% or less.

[0204] Li2O, Na2O, and K2O are components that improve the meltability of the glass, and it is preferable that the glass of composition C contain at least 0.0010% of any one or both / all of these components. The content of Na2O in the glass of composition C is preferably 0% or more and 5.0% or less.

[0205] The content of Na2O in the glass of composition C is more preferably 0.0050% or more, further preferably 0.010% or more, particularly preferably 0.020% or more, and most preferably 0.030% or more.

[0206] On the other hand, if the glass of composition C contains too much Na2O, the millimeter wave transmittance may decrease. The Na2O content in the glass of composition C is more preferably 3.0% or less, even more preferably 2.0% or less, still more preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably 0.20% or less.

[0207] The content of K2O in the glass of composition C is preferably 0.0050% or more, more preferably 0.010% or more, even more preferably 0.020% or more, and particularly preferably 0.030% or more.

[0208] On the other hand, if the glass of composition C contains too much KO, the millimeter wave transmittance may decrease. The KO content in the glass of composition C is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably 0.20% or less.

[0209] Glass of composition C is more preferable because it maintains solubility while improving weather resistance by containing both Na2O and K2O, and is also expected to have the effect of increasing millimeter wave transmittance. By adjusting the content of Na2O and / or K2O to the above-mentioned specified amounts, glass of composition C can be used as a window material that also has good compatibility with other components. Furthermore, by adjusting the content of Na2O and / or K2O to the above-mentioned ranges, glass of composition C can achieve high millimeter wave transmittance.

[0210] The Li2O content in the glass of composition C is preferably 0% or more and 5.0% or less. Li2O is a component that improves the meltability of the glass, facilitates increasing the Young's modulus, contributes to improving the strength of the glass, and is also expected to have the effect of increasing the millimeter wave transmittance.

[0211] When Li2O is contained in the glass of composition C, the content is preferably 0.0010% or more, more preferably 0.0020% or more, and even more preferably 0.0030% or more.

[0212] On the other hand, if the Li2O content in the glass of composition C is too high, devitrification or phase separation may occur during glass production, making production difficult. Therefore, the Li2O content in the glass of composition C is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably 0.20% or less.

[0213] When an alkali is contained, the Na2O / R2O ratio in the glass of composition C should be 0 or more and 0.90 or less in order to improve weather resistance and millimeter wave transmittance. If the Na2O / R2O ratio is too small or too large, the effects of improving weather resistance and millimeter wave transmittance may not be sufficiently obtained.

[0214] When Li2O is contained in the glass of composition C, the lower limit of Na2O / R2O is preferably 0.010 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more.

[0215] Furthermore, when the glass of composition C does not contain Li2O, the lower limit of Na2O / R2O is preferably slightly larger than when Li2O is contained, and is preferably 0.010 or more, more preferably 0.20 or more, and even more preferably 0.40 or more.

[0216] When an alkali is contained, the upper limit of Na2O / R2O in the glass of composition C is preferably 0.80 or less, more preferably 0.60 or less, and even more preferably 0.40 or less, when Li2O is contained.

[0217] Furthermore, when the glass of composition C does not contain Li2O, the upper limit of Na2O / R2O should be slightly larger than when Li2O is contained, and is preferably 0.90 or less, more preferably 0.70 or less, and even more preferably 0.55 or less.

[0218] When an alkali is contained, the K2O / R2O ratio in the glass of composition C should be 0 or more and 0.70 or less in order to improve weather resistance and millimeter wave transmittance. If the K2O / R2O ratio is too small or too large, the effect of improving millimeter wave transmittance may not be sufficiently obtained.

[0219] When Li2O is contained, the lower limit of K2O / R2O in the glass of composition C is preferably 0.010 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more.

[0220] Furthermore, when the glass of composition C does not contain Li2O, the lower limit of K2O / R2O is preferably slightly larger than when Li2O is contained, and is preferably 0.010 or more, more preferably 0.20 or more, and even more preferably 0.40 or more.

[0221] In the glass of composition C, when Li2O is contained, the upper limit of K2O / R2O is preferably 0.70 or less, more preferably 0.60 or less, and even more preferably 0.40 or less.

[0222] Furthermore, when the glass of composition C does not contain Li2O, the upper limit of K2O / R2O should be slightly larger than when Li2O is contained, and is preferably 0.70 or less, and more preferably 0.60 or less.

[0223] When an alkali is contained, the Li2O / R2O ratio in the glass of composition C may be set to 0 or more and 1.0 or less in order to improve weather resistance and millimeter wave transmittance. Li2O has the effect of improving millimeter wave transmittance compared to Na2O and K2O, and a larger Li2O / R2O ratio is preferable.

[0224] When Na2O and / or K2O is contained in the glass of composition C, the lower limit of Li2O / R2O is preferably 0.010 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more.

[0225] Furthermore, the upper limit of Li2O / R2O in the glass of composition C is preferably 1.0 or less, more preferably 0.90 or less, and even more preferably 0.80 or less, from the viewpoint of improving weather resistance and suppressing phase separation.

[0226] The glass of composition C may also contain RO, which represents the total content of MgO, CaO, SrO, and BaO, in order to improve weather resistance and suppress devitrification and phase separation during the production of glass sheets.

[0227] The RO content in the glass of composition C is preferably 1.0% or more, more preferably 5.0% or more, even more preferably 7.0% or more, still more preferably 9.0% or more, particularly preferably 11% or more, and most preferably 13% or more.

[0228] On the other hand, if the RO content in glass of composition C is too high, devitrification may occur. Furthermore, as the relative permittivity and dielectric loss tangent increase, millimeter wave transmittance may also decrease. Therefore, the RO content should be 25% or less. The RO content in glass of composition C is preferably 22% or less, more preferably 20% or less, even more preferably 19% or less, particularly preferably 18% or less, and most preferably 17% or less.

[0229] The content of MgO in the glass of composition C may be 0% or more and 20% or less. MgO is a component that promotes the melting of glass raw materials and improves weather resistance and Young's modulus.

[0230] The content of MgO in the glass of composition C is preferably 0.10% or more, more preferably 1.0% or more, even more preferably 2.0% or more, particularly preferably 3.0% or more, and most preferably 4.0% or more.

[0231] If the MgO content in the glass of composition C is 20% or less, devitrification is unlikely to occur. Furthermore, if the MgO content in the glass of composition C is too high, the relative permittivity and dielectric loss tangent increase, which may result in a decrease in millimeter wave transmittance. Therefore, the MgO content is preferably 15% or less, more preferably 10% or less, even more preferably 8.0% or less, particularly preferably 7.0% or less, and most preferably 6.0% or less.

[0232] The CaO content in the glass of composition C is preferably 0% or more and 20% or less. CaO is a component that promotes the melting of glass raw materials and also contributes to suppressing devitrification.

[0233] The CaO content in the glass of composition C is preferably 0.10% or more, more preferably 1.0% or more, even more preferably 2.0% or more, particularly preferably 3.0% or more, and most preferably 4.0% or more.

[0234] If the CaO content in the glass of composition C is 20% or less, devitrification is unlikely to occur. Furthermore, if the CaO content in the glass of composition C is too high, the relative permittivity and dielectric loss tangent increase, which may result in a decrease in millimeter wave transmittance. Therefore, the CaO content is preferably 15% or less, more preferably 10% or less, even more preferably 8.0% or less, particularly preferably 7.0% or less, and most preferably 6.0% or less.

[0235] The SrO content in the glass of composition C is preferably 0% or more and 20% or less. SrO is a component that promotes the melting of glass raw materials and also contributes to suppressing devitrification.

[0236] The SrO content in the glass of composition C is preferably 0.10% or more, more preferably 1.0% or more, even more preferably 2.0% or more, particularly preferably 3.0% or more, and most preferably 4.0% or more.

[0237] If the SrO content in the glass of composition C is 20% or less, devitrification is unlikely to occur. Furthermore, if the SrO content in the glass of composition C is too high, the Young's modulus may decrease and the millimeter wave transmittance may decrease due to an increase in the relative permittivity and dielectric loss tangent. Therefore, the SrO content is preferably 15% or less, more preferably 10% or less, even more preferably 8.0% or less, particularly preferably 7.0% or less, and most preferably 6.0% or less.

[0238] The content of BaO in the glass of composition C is preferably 0% or more and 10% or less. BaO is a component that promotes the melting of glass raw materials and also contributes to suppressing devitrification.

[0239] The content of BaO in the glass of composition C is preferably 0.010% or more, more preferably 0.020% or more, further preferably 0.030% or more, and particularly preferably 0.040% or more.

[0240] If the BaO content in the glass of composition C is 10% or less, the glass is less susceptible to devitrification and weather resistance can be maintained. Furthermore, if the BaO content in the glass of composition C is too high, the Young's modulus may decrease and the millimeter wave transmittance may decrease due to an increase in the relative dielectric constant and dielectric loss tangent. Therefore, the BaO content is preferably 8.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably 0.10% or less.

[0241] The Fe2O3 content in the glass of composition C is preferably 0.0010% or more and 1.0% or less. If the Fe2O3 content in the glass of composition C is less than 0.0010%, it may not be usable for applications requiring heat insulation. Furthermore, it may be necessary to use expensive raw materials with low iron content to manufacture glass sheets. Furthermore, if the Fe2O3 content in the glass of composition C is less than 0.0010%, more heat radiation than necessary may reach the bottom of the melting furnace during glass melting, which may place a strain on the melting furnace.

[0242] The content of Fe2O3 in the glass of composition C is preferably 0.0030% or more, more preferably 0.010% or more, even more preferably 0.050% or more, and particularly preferably 0.10% or more.

[0243] On the other hand, if the Fe2O3 content in the glass of composition C exceeds 1%, heat transfer by radiation may be hindered during production, making it difficult for the raw materials to melt. Furthermore, if the Fe2O3 content in the glass of composition C is too high, the transmittance of light in the visible range may decrease, making the glass unsuitable for use as window glass for automobiles.

[0244] The content of Fe2O3 in the glass of composition C is preferably 0.50% or less, more preferably 0.30% or less, and even more preferably 0.20% or less.

[0245] The glass of composition C may contain TiO2. If it does, the content is preferably 0.0010% or more and 5.0% or less.

[0246] For example, if the glass of composition C does not contain TiO2, a bubble layer may form on the surface of the molten glass during the production of glass sheets. This prevents the temperature of the molten glass from rising, making it difficult to refine, and reducing productivity. Therefore, in order to thin or eliminate the bubble layer formed on the surface of the molten glass, a titanium compound can be added as an antifoaming agent to the bubble layer formed on the surface of the molten glass. The titanium compound is incorporated into the molten glass and exists as TiO2.

[0247] The TiO2 content of the glass in composition C is preferably 0.0050% or more. In addition, TiO2 has an absorption property in the ultraviolet region, so it is preferable to add it when it is desired to cut ultraviolet light. In this case, the TiO2 content may be preferably 0.050% or more, and may further be 0.10% or more.

[0248] On the other hand, if the TiO2 content is too high, the liquidus temperature may rise, which may cause devitrification. Furthermore, the TiO2 content may absorb light in the visible range, resulting in yellow coloration. Therefore, the TiO2 content in the glass of composition C is preferably 5.0% or less, more preferably 0.50% or less, even more preferably 0.20% or less, and particularly preferably 0.10% or less.

[0249] Furthermore, glass with composition C can have a low tan δ by adjusting the composition, which reduces dielectric loss and enables high millimeter-wave transmittance. Similarly, the relative dielectric constant can be adjusted by adjusting the composition, suppressing the reflection of radio waves at the interface with the interlayer film and enabling high millimeter-wave transmittance.

[0250] Furthermore, the relative dielectric constant at 10 GHz of the glass of composition C is preferably 6.50 or less. If the relative dielectric constant at 10 GHz is 6.50 or less, the difference in relative dielectric constant with the interlayer film becomes small, and reflection of millimeter waves at the interface with the interlayer film can be suppressed.

[0251] The relative dielectric constant at 10 [GHz] of the glass of composition C is more preferably 6.00 or less, further preferably 5.75 or less, and particularly preferably 5.50 or less.

[0252] The lower limit of the relative dielectric constant at 10 GHz of the glass of composition C is not particularly limited, but is, for example, 4.50 or more.

[0253] Furthermore, the dielectric loss tangent at 10 GHz of the glass of composition C is preferably 0.0080 or less. If the dielectric loss tangent at 10 GHz is 0.0080 or less, the millimeter wave transmittance can be increased.

[0254] The dielectric loss tangent at 10 [GHz] of the glass of composition C is more preferably 0.0075 or less, further preferably 0.0070 or less, further preferably 0.0065 or less, particularly preferably 0.0060 or less, and most preferably 0.0055 or less.

[0255] The lower limit of the dielectric loss tangent at 10 GHz of the glass of composition C is not particularly limited, but is, for example, 0.0020 or more.

[0256] If the relative permittivity and dielectric loss tangent of the glass at 10 GHz satisfy the above ranges, high millimeter wave transmittance can be achieved even at 10 GHz to 90 GHz.

[0257] The relative dielectric constant and dielectric loss tangent of the glass at 10 GHz can be measured by the above-mentioned method.

[0258] Glass of composition C absorbs light in the near-infrared region when water is present in the glass, which reduces the transmittance of light in the near-infrared region, which can cause problems when transmitting and receiving millimeter-wave radio waves and when using infrared irradiating devices (such as laser radar).

[0259] The water content in glass can generally be expressed as the β-OH value. The β-OH value of glass with composition C is 0.70 mm -1 Preferably less than 0.60mm -1 Less than 0.50mm is more preferable -1 Less than 0.40 mm is more preferable. -1 The following is particularly preferred: β-OH can be obtained from the transmittance of glass measured using an FT-IR (Fourier transform infrared spectrophotometer) by the following formula:

[0260] β-OH=(1 / X)log10 (T A / T B ) [mm -1 ] X: sample thickness [mm] T A :Reference wave number 4000cm -1 Transmittance [%] T B : Hydroxyl group absorption wave number 3600cm -1 Minimum transmittance in the vicinity [%]

[0261] As mentioned above, glass of composition C absorbs light in the near-infrared region when water is present in the glass. Therefore, in order to improve the heat insulation properties, the β-OH value of composition C is set to 0.050 mm. -1 More than 0.10mm is preferable. -1 More preferably, 0.15 mm or more -1 More preferably, 0.20 mm or more -1 The above is particularly preferred.

[0262] The specific gravity of the glass of composition C is preferably 2.1 or more and 2.8 or less. The Young's modulus of the glass of composition C is preferably 50 GPa or more and 90 GPa or less. The average linear expansion coefficient of the glass of composition C from 50°C to 350°C is 30×10 -7 / K or higher, 60×10 -7 If the glass of composition C satisfies these conditions, it can be suitably used as a laminated glass for vehicles.

[0263] The glass of composition C preferably contains a certain amount of SiO2 or more to ensure weather resistance, and as a result, the specific gravity of the glass of composition C can be 2.1 or more. The specific gravity of the glass of composition C is preferably 2.2 or more. If the specific gravity of the glass of composition C is 2.8 or less, it is less likely to become brittle and is lightweight. The specific gravity of the glass of composition C is preferably 2.7 or less, more preferably 2.6 or less.

[0264] The glass of composition C has a high Young's modulus and therefore has high rigidity, making it more suitable for use as automotive window glass, etc. The Young's modulus of the glass of composition C is preferably 55 GPa or more, more preferably 60 GPa or more, even more preferably 65 GPa or more, particularly preferably 68 GPa or more, and most preferably 70 GPa or more.

[0265] On the other hand, in order to suppress thermal cracking of the glass plate, a low Young's modulus is preferable, and the Young's modulus of the glass of composition C is preferably 85 GPa or less, more preferably 82 GPa or less, even more preferably 80 GPa or less, particularly preferably 78 GPa or less, and most preferably 77 GPa or less.

[0266] Furthermore, the glass of composition C is preferable because the small average linear expansion coefficient suppresses the generation of thermal stress due to the temperature distribution in the glass plate, making the glass plate less susceptible to thermal cracking.

[0267] The average linear expansion coefficient of the glass of composition C from 50°C to 350°C is preferably 20 × 10 -7 / K or more, more preferably 30×10 -7 / K or more, and more preferably 35×10 -7 / K or higher.

[0268] On the other hand, if the average linear expansion coefficient becomes too large, thermal stress due to the temperature distribution in the glass sheet is likely to occur during the glass sheet forming process, annealing process, or windshield forming process, which may cause thermal cracking of the glass sheet. Furthermore, the difference in expansion between the glass sheet and a supporting member or the like becomes large, which may cause distortion and lead to cracking of the glass sheet.

[0269] The average linear expansion coefficient of the glass of composition C from 50°C to 350°C is preferably 55 x 10 -7 / K or less, and more preferably 50×10 -7 / K or less, and more preferably 45×10 -7 / K or less, and more preferably 43×10-7 / K or less, and particularly preferably 41×10 -7 / K or less, and most preferably 40×10 -7 / K or less.

[0270] The glass of composition C preferably has a T2 of 1750°C or less. The glass of composition C preferably has a T4 of 1350°C or less. The glass of composition C preferably has a T4-T L is preferably −50° C. or higher.

[0271] When T2 or T4 of the glass of composition C exceeds these predetermined temperatures, it becomes difficult to produce a large plate by a float method, a roll-out method, a down-draw method, or the like.

[0272] For the glass of composition C, T2 is more preferably 1700°C or less, and further preferably 1670°C or less.

[0273] T4 is more preferably 1300°C or lower, and further preferably 1250°C or lower.

[0274] Although there are no particular restrictions on the lower limits of T2 and T4 of the glass of composition C, in order to maintain weather resistance and glass specific gravity, T2 is typically 1500°C or higher and T4 is typically 1100°C or higher.

[0275] The T2 of the glass of composition C is preferably 1550° C. or higher, more preferably 1600° C. or higher. The T4 of the glass of composition C is preferably 1150° C. or higher, more preferably 1200° C. or higher.

[0276] Furthermore, in order to enable production by the float process, T4-T of glass of composition C was L is preferably −50° C. or more. If this difference is less than −50° C., devitrification occurs in the glass during glass molding, causing problems such as a decrease in the mechanical properties and transparency of the glass, making it difficult to obtain high-quality glass.

[0277] T4-T of glass of composition C L is more preferably 0°C or higher, and further preferably +20°C or higher.

[0278] In addition, the glass of composition C has T g The temperature is preferably 550°C or higher and 750°C or lower. g If the T of glass of composition C is within this predetermined temperature range, the glass can be bent within the range of normal manufacturing conditions. g If the temperature is lower than 550°C, there will be no problem with formability, but problems such as a decrease in weather resistance will be likely to occur. g If the temperature is lower than 550°C, the glass may become devitrified in the forming temperature range and become unable to be formed.

[0279] T of glass of composition C g is more preferably 600°C or higher, further preferably 620°C or higher, and particularly preferably 630°C or higher.

[0280] On the other hand, T g If T is too high, high temperatures are required during glass bending, making manufacturing difficult. g is more preferably 740°C or less, further preferably 730°C or less, and particularly preferably 720°C or less.

[0281] In the first glass plate 11 and the second glass plate 12 according to this embodiment, in any of the above-mentioned embodiments, that is, the glass of composition A, composition B, and composition C, the NiO content is preferably 0.01% or less.

[0282] The glass plate according to the present embodiment may contain components other than SiO2, Al2O3, B2O3, R2O, RO, TiO2, and Fe2O3 (hereinafter also referred to as "other components"), and if contained, the total content thereof is preferably 5.0% or less.

[0283] Examples of other components include ZrO2, Y2O3, Nd2O5, P2O5, GaO2, GeO2, CeO2, MnO2, CoO, Cr2O3, V2O5, Se, Au2O3, Ag2O, CuO, CdO, SO3, Cl, F, SnO2, and Sb2O3, and they may be metal ions or oxides.

[0284] The glass plate according to this embodiment has a NiO content of 0.010% or less, and the total content of other components is more preferably 5.0% or less, even more preferably 3.0% or less, particularly preferably 2.0% or less, and most preferably 1.0% or less.

[0285] In the first glass plate 11 and the second glass plate 12 according to this embodiment, if NiO is contained, NiS may be generated, which may cause glass breakage, so the NiO content is preferably 0.010% or less. The NiO content in the glass plate according to this embodiment is more preferably 0.0050% or less, and it is even more preferable that NiO is substantially not contained.

[0286] Other components may be contained in an amount of up to 5.0% for various purposes (e.g., clarification and coloring). If the content of other components exceeds 5.0%, there is a risk of reducing millimeter wave transmittance. 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.

[0287] In order to prevent environmental impact, the contents of As2O3 and PbO are preferably each less than 0.0010%.

[0288] CeO2 acts as an oxidizing agent, making it possible to control the amount of FeO and to block ultraviolet light. When the first glass plate 11 and the second glass plate 12 according to this embodiment contain CeO2, the content is preferably 0.0040% or more, more preferably 0.010% or more, even more preferably 0.050% or more, and particularly preferably 0.10% or more.

[0289] On the other hand, in order to improve productivity, the CeO2 content in the glass plate in this embodiment is preferably 1.0% or less, more preferably 0.50% or less, and even more preferably 0.30% or less.

[0290] Cr2O3 acts as an oxidizing agent, and can control the amount of FeO. When the first glass plate 11 and the second glass plate 12 according to this embodiment contain Cr2O3, the content thereof is preferably 0.0020% or more, and more preferably 0.0040% or more.

[0291] On the other hand, Cr2O3 has a color in the visible range, which may reduce the visible light transmittance. When the glass plate according to this embodiment contains Cr2O3, the content 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.

[0292] SnO acts as a reducing agent, enabling the amount of FeO to be controlled. When the first glass plate 11 and the second glass plate 12 according to this embodiment contain SnO, the 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.

[0293] On the other hand, in order to suppress defects due to SnO2 during glass plate production, the SnO2 content in the first glass plate 11 and the second glass plate 12 according to 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.

[0294] Furthermore, P2O5 is likely to cause defects in the glass in the float bath when the first glass sheet 11 and the second glass sheet 12 according to this embodiment are manufactured by the float process. Therefore, the content of P2O5 in the first glass sheet 11 and the second glass sheet 12 according to this embodiment is preferably 1.0% or less, more preferably 0.10% or less, even more preferably 0.050% or less, and particularly preferably less than 0.010%.

[0295] Furthermore, in the laminated glass 10 according to an embodiment of the present invention, when both the first glass sheet 11 and the second glass sheet 12 are borosilicate glass, at least one of the first glass sheet 11 and the second glass sheet 12 is preferably borosilicate glass having the above composition A, B, or C.

[0296] More preferably, at least the first glass plate 11 is made of borosilicate glass having composition A, B or C above.

[0297] More preferably, both the first glass plate 11 and the second glass plate 12 are made of borosilicate glass having the composition A, B or C described above.

[0298] If the second glass plate 12 is not made of borosilicate glass, the type of the glass plate is not particularly limited, and any conventional glass plate used for automobile windowpanes can be used. Specific examples include alkali aluminosilicate glass and soda-lime glass. These glass plates may be colored to the extent that their transparency is not impaired.

[0299] In an embodiment of the present invention, the first glass sheet 11 may be the borosilicate glass, and the second glass sheet 12 may be an alkali aluminosilicate glass containing 1.0% or more Al2O3, expressed as an oxide-based mole percentage. By using the alkali aluminosilicate glass for the second glass sheet 12, chemical strengthening becomes possible, as described below, and strength can be increased. Another advantage of alkali aluminosilicate glass is that it is easier to chemically strengthen than borosilicate glass.

[0300] From the viewpoint of weather resistance and chemical strengthening, the alkali aluminosilicate glass preferably contains 2.0% or more Al2O3, expressed as an oxide-based mole percentage, and even more preferably 2.5% or more.

[0301] Furthermore, in alkali aluminosilicate glass, if the content of Al2O3 is high, there is a risk of the millimeter wave transmittance decreasing, so the content is preferably 20% or less, and more preferably 15% or less.

[0302] From the viewpoint of chemical strengthening, the alkali aluminosilicate glass preferably contains 10% or more of R2O expressed as mole percentage on an oxide basis, more preferably 12% or more, and even more preferably 13% or more.

[0303] Furthermore, in alkali aluminosilicate glass, if the R2O content is high, there is a risk of a decrease in millimeter wave transmittance, so the R2O content is preferably 25% or less, more preferably 20% or less, and even more preferably 19% or less.

[0304] Specific examples of the alkali aluminosilicate glass include glasses having the following compositions: Each component is expressed in mole percentage based on oxide. <Composition D> 61%≦SiO2≦77% 1.0%≦Al2O3≦20% 0%≦B2O3≦10% 0%≦MgO≦15% 0%≦CaO≦10% 0%≦SrO≦1.0% 0%≦BaO≦1.0% 0%≦Li2O≦15% 2.0%≦Na2O≦15% 0%≦K2O≦6.0% 0%≦ZrO2≦4.0% 0%≦TiO2≦1.0% 0%≦Y2O3≦2.0% 10%≦R2O≦25% 0%≦RO≦20% (RO represents the total amount of LiO, NaO, and KO, and RO represents the total amount of MgO, CaO, SrO, and BaO.)

[0305] The soda-lime glass may also contain less than 1.0% Al2O3 in mole percent on an oxide basis. Specific examples of the glass include those with the following compositions, where each component is expressed as a mole percentage on an oxide basis: <Composition E> 60%≦SiO2≦75% 0%≦Al2O3<1.0% 2.0%≦MgO≦11% 2.0%≦CaO≦10% 0%≦SrO≦3.0% 0%≦BaO≦3.0% 10%≦Na2O≦18% 0%≦K2O≦8.0% 0%≦ZrO2≦4.0% 0.0010%≦Fe2O3≦5.0%

[0306] The thickness of first glass sheet 11 is preferably 2.50 mm or more. When first glass sheet 11 has a thickness of 2.50 mm or more, the strength of laminated glass 10 against stone chipping can be improved while maintaining high millimeter wave transmittance.

[0307] The thickness of the first glass plate 11 is preferably 2.60 mm or more, more preferably 2.70 mm or more, even more preferably 2.80 mm or more, still more preferably 2.90 mm or more, particularly preferably 3.00 mm or more, and most preferably 3.10 mm or more.

[0308] The upper limit of the thickness of the first glass sheet 11 is preferably 10.0 mm or less, preferably 8.00 mm or less, more preferably 6.00 mm or less, even more preferably 5.00 mm or less, still more preferably 4.00 mm or less, particularly preferably 3.80 mm or less, and most preferably 3.50 mm or less. A thickness of 10.0 mm or less for the first glass sheet 11 prevents the mass of the laminated glass 10 from becoming too large, which is preferable in terms of improving the fuel efficiency of the vehicle.

[0309] The thickness of the second glass sheet 12 is preferably 1.50 mm or less. When the thickness of the second glass sheet 12 is 1.50 mm or less, high millimeter wave transmittance can be maintained, and the mass of the laminated glass 10 does not become too large, which is preferable in terms of improving the fuel efficiency of the vehicle.

[0310] The thickness of the second glass plate 12 is preferably 1.30 mm or less, more preferably 1.20 mm or less, even more preferably 1.10 mm or less, still more preferably 1.00 mm or less, particularly preferably 0.900 mm or less, and most preferably 0.800 mm or less.

[0311] The lower limit of the thickness of the second glass sheet 12 is preferably 0.100 mm or more, more preferably 0.300 mm or more, and more preferably 0.500 mm or more. When the thickness of the second glass sheet 12 is 0.100 mm or more, cracks can be prevented when an object hits the laminated glass 10 from the inside of the vehicle.

[0312] The first glass sheet 11 and the second glass sheet 12 may have the same thickness or different thicknesses. In particular, it is preferable that the first glass sheet 11 is thicker than the second glass sheet 12. This increases the strength of the first glass sheet 11, which is disposed on the outside of the vehicle, in the laminated glass 10, and improves resistance to flying debris such as flying stones while the vehicle is traveling.

[0313] Furthermore, the difference in thickness between the first glass sheet 11 and the second glass sheet 12 improves the incidence angle dependency of millimeter-wave radio waves. In other words, the millimeter-wave transmittance of the laminated glass 10 can be maintained at a high level regardless of the angle of incidence of the millimeter-wave radio waves on the first glass sheet 11. This is presumably because the difference in thickness between the first glass sheet 11 and the second glass sheet 12 in the laminated glass 10 changes the phase of the radio waves at the interface between the interlayer film and the glass, thereby changing the reflection characteristics.

[0314] When the first glass plate 11 and the second glass plate 12 have different thicknesses, the thickness of the first glass plate 11 is preferably at least 1.00 mm thicker than the thickness of the second glass plate 12, more preferably at least 1.50 mm thicker, even more preferably at least 2.00 mm thicker, and particularly preferably at least 2.30 mm thicker. Within the above range, the incidence angle dependency of millimeter wave transmittance is improved.

[0315] Furthermore, when the first glass sheet 11 and the second glass sheet 12 have different thicknesses, the thickness of the first glass sheet 11 is preferably 9.50 mm or less thicker than the thickness of the second glass sheet 12, more preferably 9.00 mm or less thicker, even more preferably 7.00 mm or less thicker, still more preferably 5.00 mm or less thicker, particularly preferably 4.00 mm or less thicker, and most preferably 3.00 mm or less thicker. This makes it possible to suppress optical distortion due to the quality of the glass when the laminated glass 10 is formed.

[0316] In the laminated glass 10, the thickness of the first glass sheet 11 and the second glass sheet 12 may be constant over the entire surface, or may vary from place to place as needed, such as forming a wedge shape in which the thickness of one or both of the first glass sheet 11 and the second glass sheet 12 varies.

[0317] The first glass sheet 11 and the second glass sheet 12 are preferably glass sheets formed by, for example, the well-known float process, in which molten glass base is floated on a molten metal such as tin, and then formed into glass sheets of uniform thickness and width through strict temperature control.

[0318] Alternatively, the glass sheet may be formed by a known roll-out method or down-draw method, and may be a glass sheet having a polished surface and a uniform thickness. Here, the down-draw method is broadly divided into a slot down-draw method and an overflow down-draw method (fusion method), and both are techniques in which molten glass is continuously allowed to flow down from a forming body to form a band-shaped glass ribbon.

[0319] The second glass plate 12 may also be chemically strengthened glass that has been tempered to improve its strength. Chemical strengthening methods include, for example, ion exchange. In the ion exchange method, the glass plate is immersed in a treatment liquid (e.g., potassium nitrate molten salt) to exchange ions with small ionic radii (e.g., Na ions) contained in the glass for ions with large ionic radii (e.g., K ions), thereby generating compressive stress on the glass surface. The compressive stress is generated uniformly over the entire surface of the glass plate, and a compressive stress layer of uniform depth is formed over the entire surface of the glass plate.

[0320] The magnitude of the compressive stress on the surface of the glass sheet (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 sheet can be adjusted by the glass composition, chemical strengthening treatment time, and chemical strengthening treatment temperature, respectively. Examples of chemically strengthened glass include those obtained by chemically strengthening the above-mentioned alkali aluminosilicate glass.

[0321] The first glass plate 11 and the second glass plate 12 may have a flat shape or may have a curved shape having a curvature over the entire surface or a part thereof.

[0322] When the first glass plate 11 and the second glass plate 12 are curved, they may be curved in a single curve in either the vertical or horizontal direction, or in a multiple curve in both the vertical and horizontal directions.

[0323] When the first glass sheet 11 and the second glass sheet 12 have a compound curved shape, the radius of curvature in the vertical direction and the horizontal direction may be the same or different.

[0324] When 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.

[0325] The shapes of the main surfaces of the first glass plate 11 and the second glass plate 12 are adapted to fit the window openings of the vehicle in which they are to be installed.

[0326] [Interlayer] The interlayer film 13 according to the embodiment of the present invention is sandwiched between the first glass sheet 11 and the second glass sheet 12. The vehicle laminated glass 10 according to the embodiment of the present invention includes the interlayer film 13, which firmly bonds the first glass sheet 11 and the second glass sheet 12 together and also reduces the impact force when flying debris hits the glass sheets.

[0327] Various organic resins that are commonly used in laminated glass for automobiles can be used as the interlayer film 13. 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 ( 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), polyarate (PAR), polyallylsulfone (PASF), polybutadiene (BR), polyethersulfone (PESF), polyetheretherketone (PEEK), etc. Among these, EVA and PVB are preferred from the viewpoints of transparency and adhesion, and PVB is particularly preferred because it can impart sound insulation properties.

[0328] From the viewpoint of impact force absorption and sound insulation, the thickness of the intermediate film 13 is preferably 0.30 mm or more, more preferably 0.50 mm or more, and even more preferably 0.70 mm or more.

[0329] Moreover, from the viewpoint of suppressing a decrease in visible light transmittance, the thickness of the intermediate film 13 is preferably 1.0 mm or less, more preferably 0.90 mm or less, and even more preferably 0.80 mm or less.

[0330] The thickness of the intermediate film 13 is preferably in the range of 0.30 mm to 1.0 mm, and more preferably in the range of 0.70 mm to 0.80 mm.

[0331] The thickness of the intermediate film 13 may be constant over the entire surface, or may vary from place to place as required.

[0332] If the difference in linear expansion coefficient between the interlayer film 13 and the first glass sheet 11 or the second glass sheet 12 is large, cracks or warping may occur in the laminated glass 10 when the laminated glass 10 is produced through the heating step described below, which may result in poor appearance. Therefore, it is preferable that the difference in linear expansion coefficient between the interlayer film 13 and the first glass sheet 11 or the second glass sheet 12 is as small as possible.

[0333] The difference in the linear expansion coefficient between the interlayer film 13 and the first or second glass plate 11 or 12 may be expressed as the difference in the average linear expansion coefficient between them in a predetermined temperature range. In particular, because the resin constituting the interlayer film 13 has a low glass transition point, a predetermined difference in the average linear expansion coefficient may be set in a temperature range below the glass transition point of the resin material.

[0334] The difference in the linear expansion coefficient between the first glass sheet 11 or the second glass sheet 12 and the resin material may be set by a predetermined temperature that is equal to or lower than the glass transition point of the resin material.

[0335] The intermediate film 13 may 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.

[0336] When interlayer film 13 is an adhesive layer, there is no need to go through a heating step in the process of joining first glass plate 11 and second glass plate 12, and therefore there is little risk of the above-mentioned cracking or warping occurring.

[0337] [Other layers] The laminated glass 10 according to the embodiment of the present invention may include layers other than the first glass sheet 11, the second glass sheet 12, and the interlayer film 13 (hereinafter also referred to as "other layers"), provided that the effects of the present invention are not impaired. For example, the laminated glass 10 may include a coating layer that provides water-repellent properties, hydrophilic properties, anti-fogging properties, or the like, or an infrared-reflecting film.

[0338] The positions at which the other layers are provided are not particularly limited, and they may be provided on the surface of the laminated glass 10, or may be provided so as to be sandwiched between the first glass sheet 11, the second glass sheet 12, or the interlayer film 13.

[0339] The laminated glass 10 of this embodiment may also be provided with a black ceramic layer or the like arranged in a strip shape along part or all of the periphery for the purpose of concealing the attachment portion to the frame or the wiring conductors.

[0340] The laminated glass 10 for vehicles according to the embodiment of the present invention can be manufactured by a method similar to that used for conventionally known laminated glass. For example, by laminating a first glass sheet 11, an interlayer film 13, and a second glass sheet 12, and then applying heat and pressure, a laminated glass 10 is obtained in which the first glass sheet 11 and the second glass sheet 12 are bonded together via the interlayer film 13.

[0341] The method for manufacturing the laminated glass for vehicles 10 according to the embodiment of the present invention may, for example, include a step of heating and shaping the first glass sheet 11 and the second glass sheet 12, followed by a step of inserting the interlayer film 13 between the first glass sheet 11 and the second glass sheet 12 and applying heat and pressure. By going through these steps, the laminated glass 10 may be formed in which the first glass sheet 11 and the second glass sheet 12 are joined together via the interlayer film 13.

[0342] An example of the case where the laminated glass 10 of this embodiment is used as a window glass for an automobile will be described below with reference to the drawings.

[0343] 3 is a conceptual diagram showing a state in which the laminated glass 10 of this embodiment is attached to an opening 110 formed in the front of an automobile 100 and used as a window glass of the automobile. The laminated glass 10 used as a window glass of an automobile may have a housing (case) 120, which houses an information device or the like, attached to its surface on the interior side of the vehicle to ensure safe driving of the vehicle.

[0344] The information devices housed in the housing are devices that use cameras, radars, etc. to prevent rear-end collisions with vehicles ahead, pedestrians, obstacles, etc., and to alert the driver to danger. Examples include information receiving devices and / or information transmitting devices, which include millimeter-wave radar, stereo cameras, infrared lasers, etc., and send and receive signals. The "signals" in question are electromagnetic waves, including millimeter waves, visible light, infrared light, etc.

[0345] 4 is an enlarged view of portion S in FIG. 3, and is a perspective view showing the portion of the laminated glass 10 of this embodiment where the housing 120 is attached. The housing 120 houses a millimeter-wave radar 201 and a stereo camera 202 as information devices. The housing 120 housing the information devices is usually attached on the vehicle exterior side of the rearview mirror 150 and on the vehicle interior side of the laminated glass 10, but may also be attached to other portions.

[0346] Fig. 5 is a cross-sectional view taken along line YY in Fig. 4 and perpendicular to the horizontal line. The first glass sheet 11 of the laminated glass 10 is disposed on the vehicle exterior side. As described above, the incident angle θ of radio waves 300 used for communication between information devices such as millimeter-wave radar 201 and the main surface of the first glass sheet 11 can be evaluated at angles such as 60°, 67.5°, 20°, and 45°. [Example]

[0347] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0348] [Test Example 1] The laminated glasses of Examples 1 to 49 were produced according to the following procedure. Examples 1 to 48 correspond to working examples, and Example 49 corresponds to a comparative example. In all of the examples, the first glass plate, interlayer film, and second glass plate all had a size of 300 mm square.

[0349] <Preparation of Glass Plates 1 to 12> Twelve types of glass plates, Glasses 1 to 12, were obtained so as to have the glass compositions (unit: mol%) shown in Table 1. Specifically, molten glass was formed into a band-shaped glass ribbon by the float method or the fusion method, and the glass ribbon was gradually cooled while being transported horizontally. After that, rectangular glass substrates were cut out from the glass ribbon cooled to near room temperature to obtain the glass plates. The obtained glass plates were then cut and edge-processed to obtain glass plates with a size of 300 mm square. The specific gravity, Young's modulus, average linear expansion coefficient from 50°C to 350°C, T2, T4, and T L , glass transition temperature T g , relative permittivity ε at 10[GHz] r and dielectric tangent tanδ are shown in Table 1. In Table 1, "-" means that the data was not measured.

[0350] <Making laminated glass> (Example 1) The first glass plate was made of borosilicate glass (Glass 1) having a thickness of 3.20 mm and the composition shown in Table 1. The second glass plate was made of soda lime glass (Glass 7) having a thickness of 0.700 mm and the composition shown in Table 1. The interlayer film was made of polyvinyl butyral having a thickness of 0.76 mm. The first glass plate, the interlayer film, and the second glass plate were laminated in this order and subjected to a pressure bonding treatment (1 MPa, 130°C, 3 hours) using an autoclave to produce the laminated glass of Example 1. The laminated glass of Example 1 had a total thickness of 4.66 mm for the first glass plate, the second glass plate, and the interlayer film.

[0351] (Examples 2 to 49) Except for the points shown in Tables 2 to 7, the laminated glasses of Examples 2 to 49 were produced in the same manner as in Example 1. Glasses 8 to 12 (tempered) were chemically tempered under the following conditions.

[0352] [Glass 8 (Tempered)] The chemical strengthening treatment of Glass 8 was carried out under the following conditions. The plate-shaped glass pieces were immersed in molten potassium nitrate heated to 425°C for 1.5 hours to impart chemical strengthening. Under these conditions, the surface compressive stress obtained was approximately 800 MPa, and the depth of the stress layer (DOL) was 25 μm.

[0353] [Glass 9 (Tempered)] The chemical strengthening treatment of Glass 9 was carried out under the following conditions. The plate-shaped glass pieces were immersed in molten potassium nitrate heated to 425°C for 1.5 hours to impart chemical strengthening. Under these conditions, the surface compressive stress obtained was approximately 760 MPa, and the depth of the stress layer (DOL) was 13 μm.

[0354] [Glass 10 (tempered)] The chemical strengthening treatment of Glass 10 was carried out under the following conditions. The plate-shaped glass pieces were chemically strengthened by immersing them in molten potassium nitrate heated to 425°C for 4.0 hours. Under these conditions, the surface compressive stress obtained was approximately 900 MPa, and the depth of the stress layer (DOL) was 35 μm.

[0355] [Glass 11 (Tempered)] The chemical strengthening treatment of glass 11 was carried out under the following conditions: the plate-shaped glass piece was immersed in molten sodium nitrate heated to 450°C for 2.5 hours, and then immersed in a molten salt mixture of 98% potassium nitrate and 2% sodium nitrate heated to 425°C for 1.5 hours to impart chemical strengthening. Under these conditions, the surface compressive stress obtained was approximately 700 MPa, and the depth of the stress layer (DOL) was 120 μm.

[0356] [Glass 12 (Tempered)] The chemical strengthening treatment of glass 12 was carried out under the following conditions: the plate-shaped glass piece was immersed in molten sodium nitrate heated to 410°C for 2.1 hours, and then immersed in a molten salt mixture of 99% potassium nitrate and 1% sodium nitrate heated to 440°C for 1.0 hour to impart chemical strengthening. Under these conditions, the surface compressive stress obtained was approximately 900 MPa, and the depth of the stress layer (DOL) was 120 μm.

[0357] [Chipping resistance] The chipping resistance of the laminated glasses of Examples 1 to 49 was evaluated according to the following (1) and (2).

[0358] (1) Whether or not cracks have occurred Evaluation was performed by determining whether a crack of 5.0 mm or more occurred in the laminated glass when a pin was struck against the laminated glass under the following measurement condition 1. Here, the crack length c refers to the maximum horizontal linear distance from the start point to the end point of a crack that occurs perpendicular to the thickness direction of the glass, i.e., in the horizontal direction of a dent made by the impact, as shown in Figure 2(B), for example, when the center of the dent (point of impact) is taken as the starting point and the tip of the crack is taken as the end point. Specifically, the evaluation was carried out by the impact resistance test shown in (A) of Figure 2. Measurement conditions 1 were as follows.

[0359] <Measurement condition 1> ·Collision speed V: 40 [km / h] ·Collision angle β:90[°] Pin: Carbide pin Pin weight: 1.2g Pin tip angle: 90° Pin tip radius: 0.2 mm Planar size of laminated glass sample: 300mm x 300mm Number of replicate tests: 10

[0360] <Evaluation> 〇: No cracks of 5.0 mm or more occurred ×: Cracks of 5.0 mm or more occurred

[0361] The results are shown in Tables 2 to 7.

[0362] (2) Collision speed Evaluation can also be made by impacting a pin against the laminated glass under the following measurement condition 2, and measuring the impact speed V [km / h] of the pin when a crack length of 5.0 [mm] occurs in the laminated glass.

[0363] <Measurement condition 2> ·Collision speed V: 40, 60 [km / h] ·Collision angle β:90[°] Pin: Carbide pin Pin weight: 1.2g Pin tip angle: 90° Pin tip radius: 0.2 mm Planar size of laminated glass sample: 300mm x 300mm Number of replicate tests: 10

[0364] Here, since there is a linear relationship between the impact speed V and the crack length, the impact speed V [km / h] of the pin at which the crack length becomes 5.0 [mm] was calculated by measuring the crack length at an impact speed V of 40 [km / h] and at an impact speed V of 60 [km / h]. The results are shown in Tables 2 to 7. In Tables 2 to 7, "-" indicates that the measurement was not performed.

[0365] [Radio transparency] For the laminated glasses of Examples 1 to 49, the transmission characteristics (S21) of TM waves with a frequency F of 79 [GHz] incident at angles of incidence of 60°, 20°, and 45° were measured using the relative dielectric constant ε r and the dielectric loss tangent tanδ (δ is the loss angle) were calculated by simulation.

[0366] Specifically, the antennas were placed facing each other, and each laminated glass was placed between them so that the angles of incidence were 60°, 20°, and 45°. The transmission characteristics (S21) of TM waves with a frequency of 79 GHz were measured at a 100 mm diameter opening, with the value of 0 dB being the case when there was no radio wave-transmitting substrate, and the radio wave transmission was evaluated according to the following criteria. <Evaluation of radio wave transparency> A:-1.8[dB]≦S21 B:-2.0[dB]≦S21<-1.8[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 2 to 7. In Tables 4 to 7, the radio wave transmittance ratings of "A to E" indicate that S21 is -4.0 [dB] or higher, but it has not been determined which of A to E the rating applies to.

[0367] For Examples 3, 7, 17 to 20, and 49, the transmission characteristics (S21) of TM waves with a frequency of F [GHz] incident at an incident angle of 60° or 67.5° were calculated by simulation within the range of 10 [GHz] ≦ F [GHz] ≦ 90 [GHz]. r S21 was calculated based on the dielectric tangent tanδ. The results are shown in Figures 6 and 7.

[0368] Furthermore, for Examples 3, 7, 17 to 20, and 49, the transmission characteristics (S21) when the incident angle was set to 0° to 70° for TM waves of 79 [GHz] or 28 [GHz] were calculated by simulation. In the simulation, the relative dielectric constant ε r S21 was calculated based on the dielectric tangent tanδ. The results are shown in Figures 8 and 9.

[0369] [Table 1]

[0370] [Table 2]

[0371] [Table 3]

[0372] [Table 4]

[0373] [Table 5]

[0374] [Table 6]

[0375] [Table 7]

[0376] From the above results, all of the laminated glasses of Examples 1 to 48 had good chipping resistance.

[0377] The laminated glasses of Examples 1 to 48 also had good radio wave transmittance, with transmission characteristics S21 of -4.0 dB or more when TM radio waves with a frequency of 79 GHz were incident at angles of incidence of 60° and 45°.The laminated glasses of Examples 1 to 16 and 18 to 48 also had good radio wave transmittance, with transmission characteristics S21 of -4.0 dB or more when TM radio waves with a frequency of 79 GHz were incident at an angle of incidence of 20°.

[0378] Tables 2 to 7 do not show the results when TM waves with a frequency of 79 GHz were incident at an incident angle of 67.5°, but the transmission characteristics (S21) were at the same level as those at an incident angle of 60°. In particular, the transmission characteristics S21 of the laminated glasses of Examples 1 to 48 were -3.1 dB or higher, demonstrating good radio wave transmittance.

[0379] Furthermore, as shown in Figs. 7 and 8, the laminated glasses of Examples 3, 7, and 17 to 20 had a transmission characteristic S21 of -3.1 dB or more, particularly -1.8 dB or more, when a TM wave with a frequency of 79 GHz was incident at an incident angle of 67.5°, and thus had good radio wave transmittance.

[0380] Furthermore, as shown in Figure 8, it was found that the laminated glasses of Examples 3, 7, and 19, which have different thicknesses between the first and second panes, have small angle dependency in the transmission characteristic S21 when a TM wave with a frequency of 79 [GHz] is incident. For Examples 3 and 17, laminated glasses were actually produced according to the conditions in Tables 2 and 4, and measurements of a TM wave with a frequency of 79 [GHz] were performed while changing the angle of incidence. As a result, characteristics similar to the simulation results in Figure 8 were obtained.

[0381] 9, the laminated glasses of Examples 3, 7, and 17 to 20 had a transmission characteristic S21 of -2.0 dB or more when a TM wave with a frequency of 28 GHz was incident at an incident angle of 0 to 70 degrees. In particular, the laminated glasses of Examples 17 and 18 had a transmission characteristic S21 of -0.28 dB or more when a TM wave with a frequency of 28 GHz was incident at an incident angle of 67.5 degrees.

[0382] On the other hand, the laminated glass of Example 49 had poor chipping resistance.

[0383] The laminated glass of Example 49 had poor radio wave transmittance, with transmission characteristics S21 of less than -4.0 [dB] when TM radio waves with a frequency of 79 [GHz] were incident at incident angles of 60°, 20°, and 45°. Furthermore, as shown in Fig. 7 etc., the laminated glass of Example 49 had transmission characteristics S21 of less than -3.1 [dB] when TM radio waves with a frequency of 79 [GHz] were incident at an incident angle of 67.5°.

[0384] [Test Example 2] <Making laminated glass> (Examples 50-63) Laminated glasses of Examples 50 to 63 were produced in the same manner as in Example 1 of Test Example 1, except that the first glass plate and the second glass plate were changed as shown in Table 8. Examples 50 to 63 are all examples of working examples.

[0385] [Radio transparency] For the laminated glasses of Examples 50 to 63, the transmission characteristics (S21) of TM waves with a frequency of F [GHz] incident at an incident angle of 60°, 20°, 45°, or 67.5° were calculated by simulation within the range of 10 [GHz] ≦ F [GHz] ≦ 90 [GHz]. In the simulation, the relative dielectric constant ε r and the dielectric loss tangent tan δ. The transmission characteristic (S21) of the TM wave incident at an incident angle of 60° and having a frequency F of 79 [GHz] was evaluated in the same manner as in Test Example 1. The results are shown in Table 8 and Figures 10 to 13.

[0386] [Table 8]

[0387] As shown in Table 8 and Figures 10 and 11, the laminated glasses of Examples 50 to 63 had a transmission characteristic S21 of -4.0 [dB] or more when TM radio waves with a frequency of 79 [GHz] were incident at an incident angle of 60°, and had good radio wave transmittance.

[0388] Furthermore, as shown in Table 8, the laminated glasses of Examples 52 to 56 and 59 to 63 had a transmission characteristic S21 of -4.0 dB or more when TM waves with a frequency of 79 GHz were incident at an incident angle of 20°, demonstrating good radio wave transmittance.

[0389] Furthermore, as shown in Table 8, the laminated glasses of Examples 52, 53, 55, and 59 to 63 had a transmission characteristic S21 of -4.0 dB or more when TM radio waves with a frequency of 79 GHz were incident at an incident angle of 45°, demonstrating good radio wave transmittance.

[0390] Furthermore, as shown in Figures 10 and 11, the laminated glasses of Examples 51 to 56 and 58 to 63 had a transmission characteristic S21 of -3.1 dB or more when a TM wave with a frequency of 79 GHz was incident at an incident angle of 67.5°, and had good radio wave transmittance.

[0391] Regarding chipping resistance, the laminated glasses of Examples 50 to 63 have thicker first glass plates than the laminated glasses of Examples 1 to 48 in Test Example 1, and therefore are considered to have chipping resistance equal to or better than that of the laminated glasses of Examples 1 to 48.

[0392] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0393] This application is based on a Japanese patent application (Patent Application No. 2020-081159) filed on May 1, 2020, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0394] 10. Laminated glass for vehicles 11 First glass plate 12 Second glass plate 13 Interlayer 100 Automobiles 110 Opening 120 Housing 150 rearview mirror 201 Millimeter wave radar 202 Stereo Camera 300 Radio Waves

Claims

1. A first glass plate; A second glass plate; a laminated glass for a vehicle having an interlayer film sandwiched between the first glass plate and the second glass plate, the total thickness of the first glass plate, the second glass plate, and the interlayer film is 4.0 mm or more; The first glass plate has a molar percentage of B based on oxides. ２ O ３ a borosilicate glass containing 1.0% or more of the transmission characteristic S21 of the laminated glass for vehicles when a TM wave having a frequency of 79 GHz is incident on the first glass sheet at an incident angle of 60° is −4.0 dB or more; The laminated glass for vehicles, wherein the first glass sheet has a composition A shown below in mole percentage on an oxide basis. Composition A: 85%≦SiO2+Al2O3+B2O3≦98% 60%≦SiO 2 ≦90% 0%≦Al2O3≦10% 1.0%≦B2O3≦25% 1.0%≦R2O≦10% 0%≦RO≦9.0% 0≦Li2O / R2O≦1.0 0≦Na2O / R2O≦0.90 0≦K2O / R2O≦0.70 (R 2 O represents the total amount of Li 2 O, Na 2 O, and K 2 O, and RO represents the total amount of MgO, CaO, SrO, and BaO.) 2. The laminated glass for vehicles according to claim 1, wherein in said composition A, 0.0010%≦Fe 2 O 3 ≦1.0% is satisfied in terms of mole percentage based on oxides.

3. A laminated glass for vehicles as described in claim 1 or 2, wherein in composition A, 0%≦BaO≦2.0% is satisfied in terms of mole percentage based on oxides.

4. A laminated glass for vehicles as described in any one of claims 1 to 3, wherein the relative dielectric constant of the first glass plate at 10 GHz is 6.00 or less.

5. A first glass plate; A second glass plate; a laminated glass for a vehicle having an interlayer film sandwiched between the first glass plate and the second glass plate, the total thickness of the first glass plate, the second glass plate, and the interlayer film is 4.0 mm or more; the first glass plate is a borosilicate glass containing 1.0% or more of B 2 O 3 in terms of mole percentage based on oxides; the transmission characteristic S21 of the laminated glass for vehicles when a TM wave having a frequency of 79 GHz is incident on the first glass sheet at an incident angle of 60° is −4.0 dB or more; The composition of the first glass sheet is composition C shown below in mole percentage on an oxide basis. Composition C: 82%≦SiO2+Al2O3+B2O3≦98% 55%≦SiO 2 ≦80% 0%≦Al2O3≦20% 1.0%≦B2O3≦25% 0%≦R 2 O≦5.0% 0%≦RO≦25% (R 2 O represents the total amount of Li 2 O, Na 2 O, and K 2 O, and RO represents the total amount of MgO, CaO, SrO, and BaO.) 6. The laminated glass for vehicles according to claim 5, wherein in composition C, the molar percentages based on oxides are 63%≦SiO 2 ≦80%, 0.0010%≦R 2 O ≦5.0%, and 0.0010%≦Fe 2 O 3 ≦1.0%.

7. The laminated glass for vehicles according to claim 5 or 6, wherein in composition C, 0%≦BaO≦1.0% expressed in mole percentage on an oxide basis.

8. A laminated glass for vehicles described in any one of claims 5 to 7, wherein the relative dielectric constant of the first glass plate at 10 GHz is 6.00 or less.

9. 9. The laminated glass for vehicles according to claim 1, wherein a transmission characteristic S21 when a TM wave having a frequency of 79 GHz is incident on the first glass plate at an incident angle of 67.5° is −3.1 dB or more.

10. 10. The laminated glass for vehicles according to claim 1, wherein a transmission characteristic S21 when a TM wave having a frequency of 28 GHz is incident on the first glass plate at an incident angle of 0° to 70° is −2.0 dB or more.

11. 11. The laminated glass for vehicles according to claim 1, wherein a transmission characteristic S21 when a TM wave having a frequency of 28 GHz is incident on the first glass plate at an incident angle of 67.5° is −0.28 dB or more.

12. 12. The laminated glass for vehicles according to claim 1, wherein a transmission characteristic S21 when a TM wave having a frequency of 79 GHz is incident on the first glass plate at an incident angle of 45° is −4.0 dB or more.

13. 13. The laminated glass for vehicles according to claim 1, wherein a transmission characteristic S21 when a TM wave having a frequency of 79 GHz is incident on the first glass plate at an incident angle of 20° is −4.0 dB or more.

14. The laminated glass for a vehicle according to any one of claims 1 to 13, wherein the first glass plate is thicker than the second glass plate.

15. 15. The laminated glass for a vehicle according to claim 14, wherein the first glass plate has a thickness of 2.50 mm or more.

16. 16. The laminated glass for a vehicle according to claim 14 or 15, wherein the second glass plate has a thickness of 1.50 mm or less.

17. The second glass plate contains Al in mole percentage on an oxide basis. ２ O ３ The laminated glass for vehicles according to any one of claims 14 to 16, which is an alkali aluminosilicate glass containing 1.0% or more of

18. The laminated glass for a vehicle according to claim 17, wherein the second glass sheet is a chemically strengthened glass.

19. The second glass plate contains Al in mole percentage on an oxide basis. ２ O ３ The laminated glass for vehicles according to any one of claims 14 to 16, which is soda lime glass containing less than 1.0% of

20. The second glass plate has a molar percentage of B based on oxides. ２ O ３ The laminated glass for vehicles according to any one of claims 14 to 16, which is a borosilicate glass containing 1.0% or more of

21. 19. The laminated glass for vehicles according to claim 17 or 18, wherein the alkali aluminosilicate glass of the second glass sheet has a composition shown below in mole percentage on an oxide basis: 61%≦SiO ２ ≦77% 1.0%≦Al ２ O ３ ≦20% 0%≦B ２ O ３ ≦10% 0%≦MgO≦15% 0%≦CaO≦10% 0%≦SrO≦1.0% 0%≦BaO≦1.0% 0%≦Li ２ O≦15% 2.0%≦Na ２ O≦15% 0%≦K ２ O≦6.0% 0%≦ZrO ２ ≦4.0% 0%≦TiO ２ ≦1.0% 0%≦Y ２ O ３ ≦2.0% 10≦R ２ O≦25 0≦RO≦20 (R ２ O is Li ２ O, Na ２ O.K. ２ RO represents the total amount of MgO, CaO, SrO, and BaO.

22. The laminated glass for vehicles according to any one of claims 1 to 21, wherein the interlayer film is polyvinyl butyral.

23. The laminated glass for vehicles according to any one of claims 1 to 22, wherein the thickness of the interlayer film is in the range of 0.30 mm to 1.0 mm.

24. The laminated glass for vehicles according to any one of claims 1 to 23, which does not generate cracks of 5.0 mm or more when impacted with a pin under the following measurement conditions: <Measurement conditions> ・Collision speed V: 40 [km / h] ・Collision angle β: 90 [°] Pin: Carbide pin Pin weight: 1.2 g ・Pin tip angle: 90° Pin tip radius: 0.2 mm ・Size of laminated glass sample in plan view: 300 [mm] x 300 [mm] Number of repeated tests: 10 times

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