Laminated glass and method for producing laminated glass

Abstract

The present invention provides a laminated glass that has excellent stone chipping resistance and pedestrian protection performance. The laminated glass according to the present invention includes: a first glass plate having a first main surface and a second main surface facing the first main surface; a second glass plate having a third main surface and a fourth main surface facing the third main surface; and an interlayer film sandwiched between the second main surface of the first glass plate and the third main surface of the second glass plate. Thickness of the first glass plate is greater than thickness of the second glass plate, and surface strength of the second main surface measured by a ring-on-ring test is 300 MPa or less.

Description

Laminated glass and method for manufacturing laminated glass

[0001] This invention relates to laminated glass and a method for manufacturing laminated glass.

[0002] With the increasing sophistication of automobiles, including autonomous driving technology, there is a growing trend to mount sensor devices that integrate multiple sensors, such as monochrome cameras and millimeter-wave radar, on the inside of the windshield (WS).

[0003] Automotive weatherstripping (WS) is relatively easily damaged by flying debris kicked up by vehicles in front while driving. When the WS is damaged, it needs to be replaced, but this replacement requires sensor calibration, which increases costs. Therefore, the WS is required to act as a cover glass for sensor equipment, meaning it needs to have high resistance to damage from flying debris.

[0004] Patent Document 1 discloses a resin composition for an interlayer of laminated glass that can provide laminated glass with high chipping resistance. Patent Documents 2 and 3 disclose glass-resin composites that can effectively attenuate the impact energy of scattered fragments.

[0005] Japanese Patent Publication No. 2020-040869, Japanese Patent Publication No. 2018-145082, Japanese Patent Publication No. 2018-177601

[0006] On the other hand, glass panels for automobiles are also required to have pedestrian protection performance. Pedestrian protection performance is an indicator that evaluates pedestrian safety, assuming a scenario in which a vehicle collides with a pedestrian while in motion. In other words, the more easily the glass breaks upon pedestrian impact, the better the pedestrian protection performance. Therefore, if the glass strength is increased too much to improve resistance to stone chip breakage, the glass will become less likely to break upon pedestrian impact, resulting in lower pedestrian protection performance and failure to meet regulations. Thus, there is a trade-off relationship between stone chip breakage resistance and pedestrian protection performance, and it has been difficult to realize glass that achieves both performance levels simultaneously.

[0007] Therefore, the present invention aims to provide laminated glass with excellent resistance to stone chip breakage and pedestrian protection performance, and a method for manufacturing said laminated glass.

[0008] One embodiment of the present invention relates to a laminated glass comprising: a first glass plate having a first main surface and a second main surface facing the first main surface; a second glass plate having a third main surface and a fourth main surface facing the third main surface; and an interlayer sandwiched between the second main surface of the first glass plate and the third main surface of the second glass plate, wherein the thickness of the first glass plate is greater than the thickness of the second glass plate, and the surface strength of the second main surface, as measured by a ring-on-ring test, is 300 MPa or less.

[0009] Another embodiment of the present invention relates to a method for manufacturing laminated glass as described above, comprising damaging the second main surface of a first glass plate having a first main surface and a second main surface facing the first main surface by wet blasting, sandblasting, and sandpaper, and stacking the first glass plate, an interlayer, and a second glass plate having a third main surface and a fourth main surface facing the third main surface in this order such that the second main surface of the first glass plate and the third main surface of the second glass plate face each other.

[0010] According to the present invention, it is possible to provide laminated glass with excellent resistance to flying debris and pedestrian protection performance.

[0011] Figure 1 is a cross-sectional view of an example of laminated glass according to an embodiment of the present invention. Figure 2 is a schematic diagram of an indenter used in a crash test. Figure 3 is a conceptual diagram showing the laminated glass according to an embodiment of the present invention used as an automobile window glass. Figure 4 is an enlarged partial perspective view of portion S in the automobile in Figure 3. Figure 5 is a cross-sectional view along the line Y-Y in Figure 4.

[0012] Embodiments of the present invention will be described in detail below. In the following drawings, components and parts that perform the same function may be denoted by the same reference numerals and described accordingly, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic representations for the purpose of clearly illustrating the present invention and do not necessarily accurately represent the size or scale of the actual product. In this specification, "mass" is synonymous with "weight".

[0013] [Laminated Glass] The laminated glass according to an embodiment of the present invention (hereinafter also referred to as "this embodiment") comprises a first glass plate having a first main surface and a second main surface facing the first main surface, a second glass plate having a third main surface and a fourth main surface facing the third main surface, and an interlayer sandwiched between the second main surface of the first glass plate and the third main surface of the second glass plate, wherein the thickness of the first glass plate is greater than the thickness of the second glass plate, and the surface strength of the second main surface measured by a ring-on-ring test is 300 MPa or less.

[0014] Figure 1 shows an example of laminated glass 10 according to this embodiment. The laminated glass 10 comprises a first glass plate 11, a second glass plate 12, and an interlayer 13 sandwiched between the first glass plate 11 and the second glass plate 12. The first glass plate 11 has a first main surface S1 and a second main surface S2 facing the first main surface S1. The second glass plate 12 has a third main surface S3 and a fourth main surface S4 facing the third main surface S3. The interlayer 13 is sandwiched between the second main surface S2 of the first glass plate 11 and the third main surface S3 of the second glass plate 12.

[0015] (Thickness of the first and second glass plates) In the laminated glass 10 according to this embodiment, it is important that the thickness of the first glass plate 11 is greater than the thickness of the second glass plate 12. The greater thickness of the first glass plate 11 than the thickness of the second glass plate 12 results in superior resistance to stone chip breakage of the laminated glass. This is because, when the laminated glass 10 is used in an automobile with the first glass plate 11 on the outside of the automobile, the glass plate positioned on the outside of the automobile is thicker than the glass plate positioned on the inside of the automobile. Compared to laminated glass with the first and second glass plates having the same thickness, the rigidity of the laminated glass can be increased, thereby improving the resistance to stone chip breakage of the laminated glass. In this specification, the thickness of the glass plate refers to the average thickness of the glass measured using a constant-pressure thickness measuring instrument.

[0016] The ratio of the thickness of the first glass plate 11 to the thickness of the second glass plate 12 (thickness of the first glass plate 11 / thickness of the second glass plate 12) is preferably 1.5 to 6.0. A ratio of 1.5 or higher improves resistance to flying stones. A ratio of 6.0 or lower improves bendability. A ratio of 1.6 or higher is more preferable, 1.7 or higher is even preferable, 1.8 or higher is even preferable, and 1.9 or higher is particularly preferable. Furthermore, a ratio of 5.9 or lower is more preferable, 5.8 or lower is even preferable, 5.7 or lower is even preferable, and 5.6 or lower is particularly preferable.

[0017] The thickness of the first glass plate 11 is preferably 2.3 to 5.0 mm. A thickness of 2.3 mm or more of the first glass plate 11 provides high resistance to flying stones. Furthermore, a thickness of 5.0 mm or less of the first glass plate 11 satisfies both bendability and pedestrian protection performance. A thickness of 2.4 mm or more is more preferable, 2.5 mm or more is even more preferable, 2.6 mm or more is even more preferable, 2.7 mm or more is particularly preferable, and 4.9 mm or less is more preferable, 4.8 mm or less is even more preferable, 4.7 mm or less is even more preferable, and 4.6 mm or less is particularly preferable.

[0018] The thickness of the second glass plate 12 is preferably 0.5 to 2.0 mm. A thickness of 0.5 mm or more for the second glass plate 12 provides excellent handling and high strength. A thickness of 2.0 mm or less for the second glass plate 12 provides excellent bendability. A thickness of 0.6 mm or more is more preferable, 0.7 mm or more is even more preferable, 0.8 mm or more is even more preferable, 1.0 mm or more is particularly preferable, 1.9 mm or less is more preferable, 1.8 mm or less is even more preferable, 1.7 mm or less is even more preferable, and 1.6 mm or less is particularly preferable.

[0019] (Surface Strength) In this embodiment, it is important that the surface strength of the second main surface S2 of the laminated glass 10, as measured by a ring-on-ring test, is 300 MPa or less. Having a surface strength of 300 MPa or less on the second main surface S2 of the laminated glass 10 provides excellent pedestrian protection performance. This is because, when the laminated glass 10 is used in an automobile with the first glass plate 11 facing the outside of the automobile, if the surface strength of the second main surface S2, which is the back surface of the pedestrian collision surface, is low, cracks originating from the second main surface S2 during a pedestrian collision are more likely to occur, thus contributing to pedestrian protection. In this embodiment, the surface strength of the second main surface S2 of the laminated glass 10 is more preferably 290 MPa or less, even more preferably 280 MPa or less, even more preferably 270 MPa or less, and particularly preferably 260 MPa or less. In the laminated glass 10 according to this embodiment, the surface strength of the second main surface S2 is preferably 100 MPa or more, more preferably 110 MPa or more, even more preferably 120 MPa or more, particularly preferably 130 MPa or more, and most preferably 140 MPa or more, from the viewpoint of improving resistance to flying stone cracks. This is because if the surface strength of the second main surface S2, which is the back surface of the pedestrian impact surface, is too low, cracks will occur originating from the second main surface S2 when a flying stone hits it, resulting in weak resistance to flying stone cracks. In other words, the surface strength of the second main surface S2 in the laminated glass 10 is preferably in the range of 100 to 300 MPa.

[0020] To achieve the above-mentioned surface strength in the laminated glass 10 according to this embodiment, methods such as damaging the second main surface S2 by wet blasting, sandblasting, or sandpaper can be used.

[0021] The surface strength of the laminated glass 10 according to this embodiment is measured by performing a ring-on-ring test as follows. First, a 50 mm square laminated glass 10 is prepared, and a 30 mm diameter lower ring is placed in the center of the fourth main surface. A 10 mm diameter upper ring is placed in the center of the first main surface, and a load is applied to the laminated glass at a displacement rate of 1 mm / min until the glass breaks. The fracture surface of the second main surface is observed, and it is assumed that the glass that broke within the upper ring in a plan view has been correctly evaluated. Then, the fracture surface of the second main surface of the first glass plate is observed, and the scratch depth of the second main surface of the first glass plate is measured, and the average scratch depth c for 10 measurement samples is determined. Using this average scratch depth c, the fracture stress is calculated from the following Griffiths formula, and this is taken as the surface strength of the second main surface.

[0022]

[0023] Here, K in the above formula ＩＣ This is the fracture toughness value of glass (MPa·m). １／２ ), Y is a shape factor of 1.78, σ ｆ This is the fracture stress (MPa).

[0024] In this embodiment, the laminated glass 10 preferably has a surface strength of 250 MPa or less on the fourth main surface S4. Having a surface strength of 250 MPa or less on the fourth main surface S4 of the laminated glass 10 provides excellent pedestrian protection. This is because if the surface strength of the fourth main surface S4, which is the back surface of the pedestrian impact surface, is low, cracks originating from the fourth main surface S4 during a pedestrian impact become more likely, thus contributing to pedestrian protection. In this embodiment, the surface strength of the fourth main surface S4 is more preferably 240 MPa or less, even more preferably 230 MPa or less, and particularly preferably 220 MPa or less. From the viewpoint of improving resistance to stone chip cracks, the surface strength of the fourth main surface S4 in this embodiment is more preferably 100 MPa or more, even more preferably 110 MPa or more, and particularly preferably 120 MPa or more. This is because if the surface strength of the fourth main surface S4, which is the back surface of the impact surface, is too low, cracks will occur originating from the fourth main surface S4 when a stone hits it, resulting in weak resistance to stone chip cracks. In other words, the surface strength of the fourth main surface S4 in the laminated glass 10 is preferably in the range of 100 to 250 MPa.

[0025] (Maximum Height Sz) In this embodiment, the laminated glass 10 preferably has a maximum height Sz of the second main surface S2 of 0.01 to 5.00 μm. Pedestrian protection performance can be enhanced by having a maximum height Sz of 0.01 μm or more for the second main surface S2 in the laminated glass 10. Also, resistance to flying stones can be enhanced by having a maximum height Sz of 5.00 μm or less for the second main surface S2 in the laminated glass 10. In this embodiment, the maximum height Sz of the second main surface S2 of 0.05 μm or more is more preferable, 0.1 μm or more is even more preferable, 0.3 μm or more is even more preferable, and 0.5 μm or more is particularly preferable. In this embodiment, the maximum height Sz of the second main surface S2 of 4.75 μm or less is more preferable, 4.60 μm or less is even more preferable, and 4.5 μm or less is particularly preferable.

[0026] To set the maximum height Sz of the second main surface S2 in the laminated glass 10 according to this embodiment to the above range, for example, a method of damaging the second main surface S2 by wet blasting, sandblasting, or sandpaper can be used.

[0027] The maximum height Sz of the second main surface S2 in the laminated glass 10 according to this embodiment is defined in ISO 25178:2021 and refers to the surface roughness when observed at 150x magnification with a laser microscope. For example, it can be measured using a laser microscope VK-X3000 manufactured by Keyence Corporation.

[0028] (Average scratch depth) In this embodiment, the average scratch depth of the second main surface S2 of the laminated glass 10 is preferably 1 to 20 μm. A high level of pedestrian protection performance can be obtained when the average scratch depth of the second main surface S2 of the laminated glass 10 is 1 μm or more. Furthermore, a pedestrian protection performance and resistance to flying stones can be achieved simultaneously when the average scratch depth of the second main surface S2 of the laminated glass 10 is 20 μm or less. In this embodiment, the average scratch depth of the second main surface S2 is more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and particularly preferably 2.5 μm or more. In this embodiment, the average scratch depth of the second main surface S2 of the laminated glass 10 is more preferably 18 μm or less, even more preferably 16 μm or less, and particularly preferably 15 μm or less.

[0029] To set the average scratch depth of the second main surface S2 in the laminated glass 10 according to this embodiment to the above range, for example, methods such as wet blasting, sandblasting, or sandpaper can be used to damage the second main surface S2.

[0030] The average scratch depth of the second main surface S2 in the laminated glass 10 according to this embodiment is determined by performing the ring-on-ring test described above, observing the fracture surface of the second main surface of the first glass plate, and measuring the scratch depth of the second main surface of the first glass plate. Ten samples are used for measurement, and the average value of their scratch depths is defined as the average scratch depth c.

[0031] (Chipping Size) The average size of the chipping on the end face of the first glass plate 11 in the laminated glass 10 according to this embodiment is preferably 40 μm or less. Having an average size of 40 μm or less of the chipping on the end face of the first glass plate 11 results in good end face machinability. The average size of the chipping on the end face of the first glass plate 11 is more preferably 38 μm or less, even more preferably 37 μm or less, and particularly preferably 35 μm or less. The average size of the chipping on the end face of the first glass plate 11 in the laminated glass 10 according to this embodiment may be 5 μm or more, may be 6 μm or more, or may be 7 μm or more. In other words, the average size of the chipping on the end face of the first glass plate 11 is preferably in the range of 5 to 40 μm.

[0032] To set the average size of the chipping on the end face of the first glass plate 11 in the laminated glass 10 according to this embodiment to the above range, examples include adjusting the grit size of the grinding wheel used for processing the end face, and adjusting the processing speed.

[0033] Here, in this embodiment, the chipping of the end face of the first glass plate 11 in the laminated glass 10 refers to the chipping that occurs at the boundary between the first main surface S1 or the second main surface S2 and the end face when the end face of the laminated glass 10 is processed into a C-chamfer shape (C0.1, angle 45°) using a #230 electroplated grinding wheel at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min. Details of the measurement method will be described later in the examples. Note that "C0.1, angle 45°" in the C-chamfer shape means that the corner of the end face of the laminated glass 10 is cut off by 0.1 mm at an angle of 45° to the end face.

[0034] In the laminated glass 10 according to the present embodiment, the average value of the chipping size of the end face of the second glass plate 12 is preferably 40 μm or less. By the average value of the chipping size of the end face of the second glass plate 12 being 40 μm or less, thermal cracking can be reduced. The average value of the chipping size of the end face of the second glass plate 12 is more preferably 38 μm or less, even more preferably 37 μm or less, still more preferably 36 μm or less, and particularly preferably 35 μm or less. In the laminated glass 10 according to the present embodiment, the average value of the chipping size of the end face of the second glass plate 12 may be 5 μm or more, may be 7 μm or more, or may be 10 μm or more. That is, the average value of the chipping size of the end face of the second glass plate 12 is preferably in the range of 5 to 40 μm.

[0035] To make the average value of the chipping size of the end face of the second glass plate 12 in the laminated glass 10 according to the present embodiment within the above range, for example, methods such as improving the mechanical properties of the glass, reducing the end face processing speed, and increasing the virtual temperature of the glass can be cited.

[0036] Here, the chipping of the end face of the second glass plate 12 in the laminated glass 10 according to the present embodiment means the chipping generated at the boundary between the third main surface S3 or the fourth main surface S4 and the end face when the end face of the laminated glass 10 is machined into a chamfered shape (C0.1, angle 45°) using an electroplated grinding wheel of #230 at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min. Details of the measurement method will be described later in the examples.

[0037] (Fracture toughness value) The fracture toughness value K of the first glass plate 11 in the laminated glass 10 according to the present embodiment ＩＣ is preferably 0.7 MPa·m １／２ or more. By the fracture toughness value K of the first glass plate 11 ＩＣ being 0.7 MPa·m １／２ or more, high spalling resistance can be realized. The fracture toughness value K of the first glass plate 11 ＩＣ is more preferably 0.71 MPa·m １／２ or more, even more preferably 0.72 MPa·m １／２ or more, and still more preferably 0.73 MPa·m １／２The above is particularly preferable. The fracture toughness value K of the first glass plate 11 in the laminated glass 10 according to this embodiment. ＩＣ From the perspective of pedestrian protection performance, it is 1.0 MPa·m １／２ The following is preferred: 0.97 MPa·m １／２ The following is more preferable: 0.95 MPa·m １／２ The following is even more preferable: namely, the fracture toughness value K of the first glass plate 11. ＩＣ The pressure range is 0.7 to 1.0 MPa·m １／２ A range of [specified range] is preferred.

[0038] The fracture toughness value K of the second glass plate 12 in the laminated glass 10 according to this embodiment. ＩＣ It is 0.72 MPa·m １／２ The above is preferable. Fracture toughness value K of the second glass plate 12 ＩＣ 0.72 MPa·m １／２ As a result of the above, the strength against impact from the fourth main surface side can be increased. Fracture toughness value K of the second glass plate 12 ＩＣ It is 0.73 MPa·m １／２ The above is more preferable, 0.74 MPa·m １／２ The above is even more preferable, 0.75 MPa·m １／２ The above is particularly preferable. The fracture toughness value K of the second glass plate 12 in the laminated glass 10 according to this embodiment. ＩＣ From the perspective of pedestrian protection performance, it is 1.0 MPa·m １／２ The following is preferred: 0.97 MPa·m １／２ The following is more preferable: 0.95 MPa·m １／２ The following is even more preferable: namely, the fracture toughness value K of the second glass plate 12. ＩＣ The pressure range is 0.72 to 1.0 MPa·m １／２ A range of [specified range] is preferred.

[0039] Fracture toughness value K of the first glass plate 11 and the second glass plate 12 in the laminated glass 10 according to this embodiment ＩＣ To set the above range, for example, SiO ２ Methods include adjusting the content of SiO, adjusting the proportion of alkaline earth metal components with low atomic numbers, and adjusting the proportion of alkali metal components with low atomic numbers. Specifically, SiO２ Since it is a component that forms a network structure, increasing its content strengthens the structure of the glass, thereby improving its fracture toughness. Furthermore, for alkaline earth metal components, the smaller the atomic number, the higher the Young's modulus, resulting in improved fracture toughness. Alkali metal components also show a similar trend as alkaline earth metal components, with smaller atomic numbers.

[0040] Fracture toughness value K ＩＣ (MPa・m １／２ ) are Young's modulus E (GPa) and surface fracture energy γ (J / m ２ It can be calculated from ) and Poisson's ratio ν (dimensionless) using the following formula.

[0041]

[0042] Furthermore, the fracture toughness value K of the first glass plate 11 and the second glass plate 12 in the laminated glass 10 according to this embodiment. ＩＣ This is measured using the Single-Edge-Precracked-Beam method (SEPB method) in accordance with JIS R1607:2015 "Test Method for Fracture Toughness of Fine Ceramics".

[0043] (Young's Modulus) In the laminated glass 10 according to this embodiment, the Young's modulus E of the first glass plate 11 is preferably 60 GPa or higher. A Young's modulus E of 60 GPa or higher of the first glass plate 11 makes it possible to obtain high resistance to flying stones. A Young's modulus E of 62 GPa or higher is more preferable, 64 GPa or higher is even more preferable, and 68 GPa or higher is particularly preferable. In the laminated glass 10 according to this embodiment, the Young's modulus E of the first glass plate 11 is more preferable to 100 GPa or less, 95 GPa or less is even more preferable, and 90 GPa or less is particularly preferable from the viewpoint of pedestrian protection performance. That is, the Young's modulus E of the first glass plate 11 is preferably in the range of 60 to 100 GPa.

[0044] In the laminated glass 10 according to this embodiment, the Young's modulus E of the second glass plate 12 is preferably 65 GPa or higher. By having a Young's modulus E of 65 GPa or higher for the second glass plate 12, it is possible to obtain high strength against impacts on the fourth main surface side. The Young's modulus E of the second glass plate 12 is more preferably 66 GPa or higher, even more preferably 67 GPa or higher, and particularly preferably 68 GPa or higher. In the laminated glass 10 according to this embodiment, the Young's modulus E of the second glass plate 12 is more preferably 100 GPa or less, even more preferably 97 GPa or less, and particularly preferably 95 GPa or less, from the viewpoint of pedestrian protection performance. That is, the Young's modulus E of the second glass plate 12 is preferably in the range of 65 to 100 GPa.

[0045] To keep the Young's modulus within the above range, adjust the types and amounts of alkaline earth metals and alkali metals, and MgO and Li ２ Increase the content of O, Y ２ O ３ , TiO ２ , ZrO ２ One possible method is to add [a certain substance]. Young's modulus can be measured by the ultrasonic pulse method based on JIS R1602:1995 "Test method for the elastic modulus of fine ceramics".

[0046] (Density) The densities r of the first glass plate 11 and the second glass plate 12 in the laminated glass 10 according to this embodiment are 2.2 to 2.8 g / cm³, respectively. ３ This is preferable. Having a density r within the above range is preferable in terms of sound insulation, bendability, and weight. The density r of the first glass plate 11 and the second glass plate 12 is 2.22 g / cm³. ３ The above is more preferable, specifically 2.25 g / cm³. ３ The above is even more preferable, and also 2.75 g / cm³. ３ The following is more preferable: 2.7 g / cm³ ３ The following are even more preferable.

[0047] The density of the first glass plate 11 and the second glass plate 12 in the laminated glass 10 according to this embodiment is measured by the Archimedes method using a bubble-free glass block of approximately 20 g cut from the glass plate.

[0048] (E / r) In the laminated glass 10 according to this embodiment, the value E / r obtained by dividing the Young's modulus E of the first glass plate 11 and the second glass plate 12 by the density r is preferably 25 to 40. When E / r is within the above range, the rigidity of the glass is increased and sufficient rigidity can be obtained. The E / r of the first glass plate 11 and the second glass plate 12 is more preferably 26 or more, even more preferably 27 or more, even more preferably 38 or less, and even more preferably 36 or less.

[0049] (Poisson's ratio) In the laminated glass 10 according to this embodiment, the Poisson's ratios of the first glass plate 11 and the second glass plate 12 are preferably 0.18 to 0.27, respectively. Having a Poisson's ratio within the above range provides excellent bendability and high rigidity. The Poisson's ratio of the first glass plate 11 and the second glass plate 12 is more preferably 0.185 or higher, even more preferably 0.19 or higher, even more preferably 0.265 or lower, and even more preferably 0.26 or lower.

[0050] The Poisson's ratios of the first glass plate 11 and the second glass plate 12 in the laminated glass 10 according to this embodiment can be measured by the ultrasonic pulse method based on JIS R1602:1995 "Test method for the elastic modulus of fine ceramics".

[0051] (Glass Transition Temperature) In the laminated glass 10 according to this embodiment, the glass transition temperature Tg of the first glass plate 11 is preferably 700°C or lower. A glass transition temperature Tg of 700°C or lower allows for high bendability. The glass transition temperature Tg of the first glass plate 11 is more preferably 690°C or lower, even more preferably 680°C or lower, and particularly preferably 670°C or lower. In the laminated glass 10 according to this embodiment, the glass transition temperature Tg of the first glass plate 11 is preferably 450°C or higher, more preferably 460°C or higher, and even more preferably 470°C or higher, from the viewpoint of glass durability and bendability. That is, the glass transition temperature Tg of the first glass plate 11 is preferably in the range of 450 to 700°C.

[0052] In the laminated glass 10 according to this embodiment, the glass transition temperature Tg of the second glass plate 12 is preferably 700°C or lower. A glass transition temperature Tg of 700°C or lower for the second glass plate 12 allows for high bendability. The glass transition temperature Tg of the second glass plate 12 is more preferably 690°C or lower, even more preferably 680°C or lower, and particularly preferably 670°C or lower. From the viewpoint of bendability, the glass transition temperature Tg of the second glass plate 12 in the laminated glass 10 according to this embodiment is preferably 470°C or higher, more preferably 475°C or higher, and even more preferably 480°C or higher. That is, the glass transition temperature Tg of the second glass plate 12 is preferably in the range of 470 to 700°C.

[0053] The glass transition temperature Tg can be measured using a differential thermal expander (TMA) in accordance with JIS R3103-3:2001.

[0054] (Average linear expansion coefficient) The average linear expansion coefficient (CTE) of the first glass plate 11 and the second glass plate 12 in the laminated glass 10 according to this embodiment at 50 to 350°C is 100 × 10⁻¹⁰ －７ It is preferable that the temperature is below / °C. The average coefficient of linear expansion is 100 × 10⁻⁶. －７ By keeping the temperature below 10°C, cracking due to thermal shock can be suppressed when the laminated glass of this embodiment is used as vehicle window glass. Furthermore, when the laminated glass of this embodiment is made into bent glass, the difference in thermal expansion due to differences in the thermal history within the plane is suppressed, resulting in bent glass with good dimensional and surface accuracy. The above average coefficient of linear expansion is 100 × 10°C. －７ Preferably below / ℃, 95 × 10 －７ / ℃ or lower is more preferable, 92 × 10 －７ A temperature of 1 / °C or lower is even more preferable, and 90 × 10 －７ A value of 30 × 10°C or lower is particularly preferable. Furthermore, from the viewpoint of suppressing cracking of the black ceramic due to the difference in thermal expansion with the black ceramic printed on the windshield, the above average linear expansion coefficient of 30 × 10°C is preferable. －７ It is preferable that the temperature is above / °C. The average coefficient of linear thermal expansion is 30 × 10⁻⁶. －７ Maintaining a temperature of 10°C or higher reduces the difference in thermal expansion with the black ceramic, thereby suppressing cracking of the black ceramic. The average coefficient of linear expansion is 35 × 10⁻⁶. －７More preferably above / ℃, 37 × 10 －７ A temperature of 38 × 10°C or higher is more preferable. －７ More preferably above / ℃, 39 × 10 －７ A temperature of 40 x 10°C or higher is particularly preferred. －７ A temperature of 1°C or higher is particularly preferable, 42 x 10 －７ A temperature of 10°C or higher is most preferable. That is, the average coefficients of linear expansion of the first glass plate 11 and the second glass plate 12 are 30 × 10⁻⁶ each. －７ / ℃~100×10 －７ A range of / °C is preferred.

[0055] In order to keep the above average coefficient of linear thermal expansion within the above range, the SiO of the glass component ２ Increase the content of R ２ O, RO, and Al ２ O ３ One method is to adjust the content of [the substance].

[0056] The above average coefficient of linear thermal expansion can be measured using a differential thermal expander (TMA) in accordance with JIS R3102:1995.

[0057] (Haze Value) The laminated glass 10 according to this embodiment preferably has a haze value of 3.0 or less. A haze value of 3.0 or less for the laminated glass 10 makes it possible to achieve both visibility and strength. The haze value of the laminated glass 10 is more preferably 2.8 or less, even more preferably 2.6 or less, and particularly preferably 2.5 or less. Furthermore, from the viewpoint of pedestrian protection performance, the haze value of the laminated glass 10 is more preferably 0.1 or more, even more preferably 0.3 or more, even more preferably 0.5 or more, and particularly preferably 1.0 or more. In other words, the haze value of the laminated glass 10 is preferably in the range of 0.1 to 3.0.

[0058] The haze value of the laminated glass 10 according to this embodiment can be measured by a haze meter.

[0059] (Resistant to flying debris cracks) In this embodiment, as shown in Figure 2, when a carbide indenter 20 weighing 1.0 g, with a tip angle of 120 degrees and a tip radius of curvature of 0.2 mm is struck perpendicularly to the surface of the first glass plate 10 on the first glass plate 11 side (the first main surface S1 in the first glass plate 11 in Figure 1) at a speed of 40 km / h, it is preferable that no cracks originating from the second main surface S2 of the first glass plate 11 occur. Details of the above impact test method will be described later in the examples.

[0060] (Composition of the first and second glass plates) At least one of the first and second glass plates in the laminated glass 10 according to this embodiment has a composition of 55 ≤ SiO2, expressed in mass % on an oxide basis. ２ ≤85 0 ≤Al ２ O ３ ≤25 0 ≤B ２ O ３ ≤20 0 ≤MgO ≤15 0 ≤CaO ≤15 0 ≤SrO ≤10 0 ≤BaO ≤10 0 ≤ZnO ≤10 0 ≤Li ２ O ≤ 5 0 ≤ Na ２ O ≤ 20 0 ≤ K ２ O ≤ 10 0 ≤ Fe ２ O ３ It is preferable to include ≤1.

[0061] The following describes the composition range of each component in the first or second glass plate (hereinafter simply referred to as "this glass plate") of this embodiment. Unless otherwise specified, the composition range of each component is expressed in mass % based on oxide. Furthermore, "substantially free" of a certain component in glass means that it is not contained except for unavoidable impurities, and that the component is not actively added. Specifically, this means that the content of each of these components in the glass is approximately 100 ppm or less.

[0062] SiO in this glass plate ２ The content is preferably 55% or more and 85% or less. ２ This contributes to improving Young's modulus, making it easier to secure the strength required for automotive applications and other uses. SiO ２If it is too little, it becomes difficult to ensure weather resistance, and the average linear expansion coefficient becomes too large, which may cause the glass plate to thermally crack. On the other hand, if ２ is too much, the viscosity during glass melting may increase, which may make glass production difficult.

[0063] In this glass plate, the content of ２ SiO is more preferably 57% or more, even more preferably 59% or more, and particularly preferably 60% or more. Also, in this glass plate, the content of ２ SiO is more preferably 83% or less, even more preferably 80% or less, and particularly preferably 78% or less.

[0064] In this glass plate, the content of ２ Al ３ O is preferably 0% or more and 25% or less. ２ Al ３ O contributes to suppressing the phase separation of the glass and improving the weather resistance. Also, it reduces the average linear expansion coefficient and makes the glass plate less likely to thermally crack. When this glass plate contains ２ Al ３ O, the content of ２ Al ３ O is more preferably 1.0% or more, even more preferably 1.2% or more, still more preferably 1.3% or more, particularly preferably 1.4% or more, and most preferably 1.5% or more. In this glass plate, the content of ２ Al ３ O is more preferably 23% or less, even more preferably 22% or less, particularly preferably 21% or less, and most preferably 20% or less from the viewpoint of keeping the temperature T １１ and T １２ of the glass low and making it easy to manufacture bent glass. Note that T １１ indicates the temperature at which the glass viscosity is 10 １１ [dPa·s], and T １２ indicates the temperature at which the glass viscosity is 10 １２ [dPa·s].

[0065] In this glass plate, the content of ２ B ３ O is preferably 0% or more and 20% or less. ２ B ３This contributes to improving glass strength and solubility. This glass plate is B ２ O ３ If it contains B ２ O ３ The content of is more preferably 0.1% or more, even more preferably 0.5% or more, particularly preferably 1% or more, and most preferably 2% or more.

[0066] On the other hand, B ２ O ３ If the content is too high, alkali elements may easily volatilize during melting and molding, which may degrade the quality of the glass and reduce its acid and alkali resistance. ２ O ３ The content of is more preferably 18% or less, even more preferably 17% or less, particularly preferably 16% or less, and most preferably 15% or less.

[0067] In this glass plate, SiO ２ +Al ２ O ３ +B ２ O ３ , that is, SiO ２ Content and Al ２ O ３ Content and B ２ O ３ The total content may be between 70% and 97%. By keeping it within the above range, the glass temperature T １１ , T １２ Adjusting the temperature makes it easier to manufacture bent glass. SiO ２ +Al ２ O ３ +B ２ O ３ It is more preferable that the amount be 96% or less, and even more preferable that it be 95% or less. However, SiO ２ +Al ２ O ３ +B ２ O ３ If there is too little of it, the weather resistance may decrease. Therefore, SiO ２ +Al ２ O ３ +B ２ O ３ It is more preferable that the amount be 71% or more, and even more preferable that it be 72% or more.

[0068] The MgO content in this glass plate is preferably 0% or more and 15% or less. MgO is a component that promotes the dissolution of glass raw materials and improves weather resistance and Young's modulus. If this glass plate contains MgO, the MgO content is more preferably 0.5% or more, and even more preferably 1% or more. Also, if the MgO content in this glass plate is 15% or less, devitrification becomes less likely. The MgO content in this glass plate is more preferably 13% or less, even more preferably 12% or less, particularly preferably 11% or less, and most preferably 10% or less.

[0069] The CaO content in this glass plate is preferably 0% or more and 15% or less. If the glass plate contains CaO, the CaO content is more preferably 0.2% or more, and even more preferably 0.3% or more. This improves the solubility of the glass raw materials and the formability of the bendable glass. Furthermore, by keeping the CaO content in this glass plate at 15% or less, an increase in the density of the glass is avoided, and low brittleness and strength are maintained. To prevent the glass from becoming brittle, the CaO content in this glass plate is more preferably 13% or less, even more preferably 12% or less, particularly preferably 11% or less, and most preferably 10% or less.

[0070] The SrO content in this glass plate is preferably 0% or more and 10% or less. If SrO is included, 0.1% or more is more preferable, and 0.3% or more is even more preferable. This improves the solubility of the glass raw materials and the formability of the bendable glass. Furthermore, by keeping the SrO content in this glass plate to 10% or less, an increase in the density of the glass is avoided, and low brittleness and strength are maintained. To prevent the glass from becoming brittle, the SrO content in this glass plate is more preferably 8% or less, even more preferably 6% or less, particularly preferably 5% or less, and most preferably substantially omitted.

[0071] The BaO content in this glass plate is preferably 0% or more and 10% or less. BaO is a component that improves the solubility of the glass raw material. If this glass plate contains BaO, the BaO content is more preferably 0.1% or more, and even more preferably 0.3% or more. Furthermore, by limiting the BaO content in this glass plate to 10% or less, an increase in glass density and a decrease in glass strength due to low brittleness can be suppressed. The BaO content in this glass plate is more preferably 8% or less, even more preferably 6% or less, particularly preferably 4% or less, and most preferably substantially absent.

[0072] The ZnO content in this glass plate is preferably 0% or more and 10% or less. ZnO is a component that improves the meltability and bendability of the glass. If ZnO is included, 0.1% or more is more preferable, and 0.3% or more is even more preferable. Furthermore, by reducing the ZnO content to 10% or less, the strength characteristics of the glass can be improved. The ZnO content is more preferably 8% or less, even more preferably 6% or less, particularly preferably 5% or less, and most preferably substantially absent.

[0073] Li in this glass plate ２ The O content is preferably 0% or more and 5% or less. ２ O is a component that improves the solubility of glass, and also contributes to increasing the strength of glass by making it easier to increase Young's modulus. Li ２ By including oxygen, the viscosity of the glass is reduced, improving the moldability of vehicle window glass, especially windshields. ２ If O is present, Li ２ The O content is more preferably 0.1% or more, even more preferably 0.3% or more, particularly preferably 0.5% or more, and most preferably 1.0% or more. On the other hand, Li ２ If the oxygen content is too high, devitrification may occur during glass manufacturing, making production difficult. Therefore, the Li content in this glass plate is important. ２ The O content is more preferably 4.7% or less, even more preferably 4.5% or less, particularly preferably 4.3% or less, and most preferably 4.2% or less.

[0074] Na in this glass plate ２ The O content is preferably 0% or more and 20% or less. ２ O is an ingredient that improves the solubility of glass. Also, Na ２ By including O, the viscosity of the glass is reduced, improving the moldability of vehicle window glass, especially windshields. ２ If O is present, Na ２ The O content is more preferably 0.5% or more, even more preferably 1.0% or more, particularly preferably 2% or more, and most preferably 2.5% or more. On the other hand, Na ２ If there is too much oxygen, the average coefficient of linear thermal expansion becomes too large, making the glass plate prone to thermal cracking. Therefore, the Na content in this glass plate is high. ２ The O content is more preferably 18% or less, even more preferably 17% or less, particularly preferably 16% or less, and most preferably 15% or less.

[0075] K in this glass plate ２ The O content is preferably 0% or more and 10% or less. ２ O is a component that improves the solubility of glass. This glass plate is K ２ If O is present, K ２ The O content is more preferably 0.1% or more, even more preferably 0.3% or more, even more preferably 0.5% or more, particularly preferably 0.7% or more, and most preferably 1.0% or more. On the other hand, K ２ If the O content is too high, the average coefficient of linear thermal expansion becomes too large, making the glass plate prone to thermal cracking. Therefore, K in this glass plate ２ The O content is more preferably 8% or less, even more preferably 6% or less, and particularly preferably 5% or less.

[0076] Fe in this glass plate ２ O ３ The content is preferably 0% or more and 1% or less. Fe ２ O ３ Fe may be included in glass to impart heat-shielding properties. ２ O ３ The content refers to the content of FeO, an oxide of divalent iron, and Fe, an oxide of trivalent iron. ２ O３ This refers to the total amount of iron, including [specific iron].

[0077] This glass plate is Fe ２ O ３ If it contains Fe ２ O ３ The content of is more preferably 0.005% or more, even more preferably 0.007% or more, even more preferably 0.01% or more, particularly preferably 0.015% or more, and most preferably 0.02% or more. On the other hand, Fe ２ O ３ If the content of is too high, the transmittance in the visible range may decrease. Therefore, the Fe content in this glass plate ２ O ３ The content of is preferably 1% or less, more preferably 0.9% or less, and even more preferably 0.8% or less.

[0078] This glass plate is made of the above SiO ２ Al ２ O ３ , B ２ O ３ , MgO, CaO, SrO, BaO, ZnO, Li ２ O, Na ２ O, K ２ O, and Fe ２ O ３ Other ingredients (hereinafter also referred to as "other ingredients") may be included, and if other ingredients are included, their total content is preferably 3% or less.

[0079] Other components include, for example, ZrO ２ , Y ２ O ３ ,TiO ２ , CEO ２ , Nd ２ O ５ GaO ２ , GeO ２ MnO ２ NiO, Cr ２ O ３ , V ２ O ５ Er ２ O ３ Au ２ O ３ Ag ２ O, CuO, CdO, MoO３ SO ３ Cl, F, SnO ２ Sb ２ O ３ These include metal ions and oxides. Other components may be included for various purposes (e.g., clarification and coloring).

[0080] (β-OH value) In the first and second glass plates in this embodiment, the presence of moisture in the glass plate increases the adhesion between the glass plate and the interlayer. Also, the moisture in the glass plate is T １１ and T １２ Because it has the effect of lowering the temperature, bending the glass plate becomes easier. For this reason, it is preferable that the first glass plate and the second glass plate in this embodiment contain a certain amount of moisture. The moisture content in the glass plate can generally be expressed by a value called the β-OH value.

[0081] In this embodiment, at least one of the first glass plate and the second glass plate has a β-OH value of 0.050 mm －１ Preferably, it should be 0.10 mm or more. －１ The above is more preferable, 0.15 mm －１ The above is even more preferable, 0.20 mm －１ The above is particularly preferable. β-OH is obtained from the transmittance of the glass measured using an FT-IR (Fourier Transform Infrared Spectrophotometer) by the following formula: β-OH = (1 / X) log １０ (T Ａ / T Ｂ ) [mm －１ ] X: Sample thickness [mm] T Ａ :Reference wave number 4000cm －１ Transmittance [%] in T Ｂ Hydroxyl group absorption wavenumber 3600 cm －１ Minimum transmittance in the vicinity [%]

[0082] On the other hand, if the moisture content in the glass plate is too high, it may affect the network structure of the glass and worsen its resistance to stone chip cracks. Therefore, the β-OH value should be 0.70 mm. －１ The following is preferred: 0.60 mm －１ The following is more preferable: 0.50 mm －１The following is even more preferable: 0.40 mm －１ The following are particularly preferable.

[0083] (Forming of glass plates) In this embodiment, the first and second glass plates are preferably float glass formed by a known float method. In the float method, molten glass material is floated on a molten metal such as tin, and glass with uniform thickness and width can be formed by precise temperature control, as well as large-area glass.

[0084] Alternatively, glass plates formed by known roll-out or down-draw methods may be used, and the surface may be polished, resulting in glass plates with uniform thickness. The down-draw method is broadly classified into the slot down-draw method and the overflow down-draw method (fusion method), but both are methods in which molten glass is continuously flowed down from a molded body to form a strip-shaped glass ribbon.

[0085] The shapes of the first and second glass plates in this embodiment are not particularly limited, but the area of ​​the main surface is 250,000 mm². ２ The above is preferable, and 450,000 mm ２ The above is more preferable, 900,000 mm ２ The above is even more preferable. If the glass plate area is within the above range, it can accommodate various vehicle types. Furthermore, if the glass plate area is too large, handling becomes difficult, the temperature distribution during heating becomes uneven, and the dimensional accuracy after bending deteriorates, increasing the difficulty of the bending process. Therefore, the main surface area should be 4,000,000 mm². ２ The following is preferable: 3,500,000 mm ２ The following is more preferable: 3,000,000 mm ２ The following are even more preferable.

[0086] The first and second glass plates in this embodiment may be glass that has undergone strengthening treatment by air cooling or chemical strengthening. The strength of the glass can be increased by performing the above treatments.

[0087] Here, air-cooled strengthening is a process that forms a compressive stress layer on the glass surface through thermal strengthening. Specifically, a uniformly heated glass plate is rapidly cooled from a temperature near its softening point, and compressive stress is formed on the glass surface due to the temperature difference between the glass surface and the inside of the glass. The compressive stress is generated uniformly across the entire surface of the glass, forming a compressive stress layer of uniform depth across the entire surface of the glass. Thermal strengthening is more suitable for strengthening thick glass plates than chemical strengthening.

[0088] Chemical strengthening is a process that forms a compressive stress layer on the glass surface by exchanging alkali metal ions with small ionic radii (typically Li ions or Na ions) on the glass surface with alkali metal ions with larger ionic radii (typically Na ions or K ions) at a temperature below the glass transition temperature. Chemical strengthening can be carried out by known methods, such as the ion exchange method. In the ion exchange method, a glass plate is immersed in a treatment solution (e.g., molten potassium nitrate), and compressive stress is generated on the glass surface by exchanging ions with small ionic radii (e.g., Na ions) contained in the glass with ions with large ionic radii (e.g., K ions). The magnitude of the compressive stress on the glass plate surface (hereinafter also called surface compressive stress CS) and the depth DOL of the compressive stress layer formed on the glass plate surface can be adjusted by the glass composition, chemical strengthening treatment time, and chemical strengthening treatment temperature, respectively.

[0089] (Bent Glass) The first glass plate and the second glass plate in this embodiment may be bent glass. The bent glass may be bent glass obtained by forming the flat first glass plate or the second glass plate into a curved shape by gravity forming or press forming or the like.

[0090] Bent glass is glass that curves with a predetermined curvature, and may be single-curved glass that curves in only one direction, either vertically or horizontally, or double-curved glass that curves in both vertically or horizontally.

[0091] It is preferable that the minimum radius of curvature of the bent glass is between 500 mm and 100,000 mm. The radius of curvature of the bent glass is calculated by shape simulation based on the amount of warpage inherent in the sample, which is determined by self-weight deflection correction using a double-sided difference mode laser displacement meter (Dyvoce manufactured by Kozu Seiki Co., Ltd.), and the radius of curvature is determined from the shape obtained from the simulation.

[0092] In the method for manufacturing bent glass, the bent glass is formed by heating and bending the flat first and second glass plates. One method for forming bent glass is to place the heated glass on a mold and press it from above with a pressing device to form the bend. Another method involves placing a flat piece of glass on a mold having a bending surface that corresponds to the desired curved surface, then transporting the mold into a heating furnace and heating the glass in the furnace to near its glass softening point. With this forming method, the glass bends along the bending surface of the mold due to its own weight as it softens, thus producing glass with the desired curved surface.

[0093] In this embodiment, bending by the above-described press means is preferred from the viewpoint of improving productivity and surface accuracy after molding. The bending method by the above-described press means is not particularly limited, and methods such as those described in International Publication No. 2016 / 093031 can be appropriately adopted. The bending method by the above-described press means will be described exemplified below.

[0094] First, the flat first and second glass plates are transported to the press area by a conveyor belt or the like. Next, in the press area, the flat first and second glass plates are heated to a temperature at which they can be bent and softened. Here, the temperature at which they can be bent is, for example, when the glass viscosity is 10 １１ The temperature T at which [dPa·s] occurs １１ That concludes the explanation. Note that the heating may also be performed using a heater in a heating furnace during the process of transporting the material to the press area via a conveyor belt, etc. Furthermore, the heating temperature (≧T) １１ The bending time under conditions that maintain the above can be set to, for example, 1 second or more.

[0095] A lower press die (female die) and an upper press die (male die) are positioned in the press area. The upper surface shape of the female die and the lower surface shape of the male die correspond to the curved shapes of the first and second glass plates that are bent in the direction of transport and perpendicular to it. The female die can move up and down between a waiting position below the transport conveyor and a pressing position above it. After the glass is transferred from the transport conveyor, the female die, with the glass placed on it, rises from a predetermined raised position to the pressing position above the transport conveyor, thereby press-forming the glass.

[0096] Next, the press-formed glass is transported to the cooling area by a transport shuttle or similar means. In the cooling area, the glass is cooled by blowing cooling air onto it.

[0097] The bent glass is formed through the above process. Although the bending of the first and second glass plates has been described above, the bending may also be performed on the laminated glass. When performing this type of bending, the first glass plate is placed face down on the mold and the process is carried out.

[0098] (Interlayer) The interlayer 13 according to this embodiment is sandwiched between the first glass plate 11 and the second glass plate 12. The laminated glass 10 of this embodiment, by including the interlayer 13, firmly adheres the first glass plate 11 and the second glass plate 12 and can mitigate the impact force when scattered fragments collide with the glass plate.

[0099] As the interlayer 13, various organic resins commonly used in laminated glass can be used. Examples of organic resins include 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), and polyvinyl phosphate. Materials such as maar (PVF), polyvinyl alcohol (PVAL), vinyl acetate resin (PVAc), ionomer (IO), polymethylpentene (TPX), vinylidene chloride (PVDC), polysulfone (PSF), polyvinylidene fluoride (PVDF), methacrylic-styrene copolymer resin (MS), polyalate (PAR), polyallyl sulfone (PASF), polybutadiene (BR), polyethersulfone (PESF), or polyetheretherketone (PEEK) can be used. Among these, EVA and PVB are preferred from the viewpoint of transparency and adhesion, and PVB is particularly preferred because it can provide sound insulation.

[0100] The thickness of the interlayer 13 is preferably 0.300 mm or more, more preferably 0.500 mm or more, and even more preferably 0.700 mm or more, from the viewpoint of impact force mitigation and sound insulation. Furthermore, the thickness of the interlayer 13 is preferably 1.00 mm or less, more preferably 0.900 mm or less, and even more preferably 0.800 mm or less, from the viewpoint of suppressing a decrease in visible light transmittance. Furthermore, the thickness of the interlayer 13 is preferably in the range of 0.300 mm to 1.00 mm, and more preferably in the range of 0.700 mm to 0.800 mm. The thickness of the interlayer 13 may be constant throughout the entire surface, or it may vary from place to place as needed. In this specification, the thickness of the interlayer refers to the thickness calculated by measuring the average thickness of the laminated glass 10 with a constant-pressure thickness measuring instrument and subtracting the average thickness of the first glass plate 11 and the average thickness of the second glass plate 12 from the average thickness of the laminated glass 10.

[0101] If the difference in the coefficient of linear expansion between the interlayer 13 and the first glass plate 11 or the second glass plate 12 is large, cracks and warping may occur in the laminated glass 10 when it is manufactured through the heating process described later, potentially causing defects in appearance. Therefore, it is preferable that the difference between the coefficient of linear expansion between the interlayer 13 and the first glass plate 11 or the second glass plate 12 be as small as possible. The difference between the coefficient of linear expansion between the interlayer 13 and the first glass plate 11 or the second glass plate 12 may be expressed as the difference between the average coefficients of linear expansion over a predetermined temperature range.

[0102] In particular, since the resin constituting the interlayer 13 has a low glass transition temperature, a predetermined average difference in linear thermal expansion coefficients may be set within a temperature range below the glass transition temperature of the resin material. The difference in linear thermal expansion coefficients between the first glass plate 11 or the second glass plate 12 and the resin material may be set by a predetermined temperature below the glass transition temperature of the resin material.

[0103] Furthermore, an adhesive layer containing an adhesive may be used as the interlayer 13. The adhesive is not particularly limited, but for example, acrylic adhesives or silicone adhesives can be used. When the interlayer 13 is an adhesive layer, there is no need to go through a heating process in the bonding process between the first glass plate 11 and the second glass plate 12, so there is less risk of the above-mentioned cracking or warping occurring.

[0104] (Total Thickness) In the laminated glass 10 of this embodiment, the total thickness of the first glass plate 11, the second glass plate 12, and the interlayer 13 is preferably 2.80 mm or more. Sufficient strength can be obtained with a total thickness of 2.80 mm or more. The total thickness is more preferably 3.00 mm or more, even more preferably 3.50 mm or more, even more preferably 4.00 mm or more, particularly preferably 4.50 mm or more, and most preferably 4.70 mm or more. Furthermore, from the viewpoint of weight reduction, the total thickness may be 6.00 mm or less, preferably 5.80 mm or less, more preferably 5.60 mm or less, and even more preferably 5.40 mm or less.

[0105] (Other Layers) The laminated glass 10 of this embodiment may include layers other than the first glass plate 11, the second glass plate 12, and the interlayer 13 (hereinafter also referred to as "other layers"), to the extent that they do not impair the effects of the present invention. For example, it may include a coating layer that provides water-repellent, hydrophilic, or anti-fogging functions, or an infrared reflective film. The position in which the other layers are provided is not particularly limited, and they may be provided on the surface of the laminated glass 10, or they may be provided so as to be sandwiched between the first glass plate 11, the second glass plate 12, or the interlayer 13. Furthermore, the laminated glass 10 of this embodiment may include a black ceramic layer or the like that is arranged in a strip shape on part or all of the peripheral edge for the purpose of concealing mounting parts to frames, wiring conductors, etc.

[0106] (Method for manufacturing laminated glass) The method for manufacturing the laminated glass 10 of this embodiment involves stacking a first glass plate 11, an interlayer 13, and a second glass plate 12 in this order, and then going through the steps of heating and pressurizing to obtain laminated glass 10 in which the first glass plate 11 and the second glass plate 12 are joined together via the interlayer 13.

[0107] The manufacturing method of the laminated glass 10 of this embodiment includes damaging the second main surface S2 of a first glass plate 11 having a first main surface S1 and a second main surface S2 facing the first main surface S1 by wet blasting, sandblasting, and sandpaper, and then laminating the first glass plate 11, the interlayer 13, and the second glass plate 12 having a third main surface S3 and a fourth main surface S4 facing the third main surface S3 in the order that the second main surface S2 of the first glass plate 11 and the third main surface S3 of the second glass plate 12 face each other. By damaging the second main surface S2 of the first glass plate 11 on the side facing the second glass plate 12, the surface strength of the second main surface S2 is set to 300 MPa or less. As a result, when the laminated glass 10 is used in a vehicle with the first glass plate 11 on the outside of the vehicle, cracks originating from the second main surface S2 that occur in the event of a pedestrian collision become more likely to occur, and the pedestrian protection performance is improved.

[0108] The scratching of the second main surface S2 of the first glass plate 11 is more preferably carried out so that the surface strength of the second main surface S2 is 290 MPa or less, even more preferably 280 MPa or less, even more preferably 270 MPa or less, and particularly preferably 260 MPa or less. Furthermore, from the viewpoint of improving resistance to stone chip cracking, the scratching of the second main surface S2 is preferably carried out so that the surface strength is 100 MPa or more, even more preferably 110 MPa or more, even more preferably 120 MPa or more, particularly preferably 130 MPa or more, and most preferably 140 MPa or more. In other words, the scratching of the second main surface S2 of the first glass plate 11 is preferably carried out so that the surface strength of the second main surface S2 is 100 to 300 MPa.

[0109] The manufacturing method for the laminated glass 10 according to this embodiment may involve, for example, a step of heating and shaping the first glass plate 11 and the second glass plate 12, followed by a step of inserting the interlayer 13 between the first glass plate 11 and the second glass plate 12, and then heating and pressurizing the interlayer. By going through such a process, the laminated glass 10 may be configured such that the first glass plate 11 and the second glass plate 12 are joined via the interlayer 13.

[0110] (Vehicle Window Glass) The laminated glass 10 of this embodiment is suitably used as vehicle window glass. An example of using the laminated glass 10 of this embodiment as vehicle window glass will be described below with reference to the drawings. Figure 3 is a conceptual diagram showing the laminated glass 10 of this embodiment installed in an opening 110 formed in front of an automobile 100 and used as an automobile window glass. The laminated glass 10 used as an automobile window glass may have a housing (case) 120 containing information devices, etc., attached to its inner surface on the vehicle side to ensure the safety of the vehicle while driving.

[0111] Furthermore, the information devices housed within the housing are devices that use cameras, radar, etc., to prevent rear-end collisions and impacts with vehicles, pedestrians, obstacles, etc., in front of the vehicle, and to warn the driver of danger. Examples include information receiving devices and / or information transmitting devices, which include millimeter-wave radar, stereo cameras, infrared lasers, etc., and transmit and receive signals. The "signals" refer to electromagnetic waves, including millimeter waves, visible light, infrared light, etc.

[0112] Figure 4 is a magnified partial perspective view of portion S in the automobile of Figure 3, showing the portion where the housing 120 is attached to the laminated glass 10 of this embodiment. The housing 120 houses a millimeter-wave radar 201 and a stereo camera 202 as information devices. The housing 120, which houses the information devices, is usually mounted on the outside of the vehicle from the rearview mirror 150 and on the inside of the vehicle from the laminated glass 10, but it may be mounted on other parts as well.

[0113] Figure 5 is a cross-sectional view taken in a direction perpendicular to the horizontal line, including the Y-Y line in Figure 4. In the laminated glass 10, it is preferable that the first glass plate 11 is positioned on the outside of the vehicle. With the above configuration, a windshield with high resistance to stone chip breakage and rigidity, as well as being lightweight and having a high aesthetic appeal with its gray color, can be realized.

[0114] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the embodiments described above, and can be modified and improved as appropriate. Furthermore, the material, shape, dimensions, number, and placement of each component in the embodiments described above are arbitrary and not limited as long as they can achieve the present invention.

[0115] As described above, the following are disclosed in this specification: [1] Laminated glass comprising: a first glass plate having a first main surface and a second main surface facing the first main surface; a second glass plate having a third main surface and a fourth main surface facing the third main surface; and an interlayer sandwiched between the second main surface of the first glass plate and the third main surface of the second glass plate, wherein the thickness of the first glass plate is greater than the thickness of the second glass plate, and the surface strength of the second main surface measured by a ring-on-ring test is 300 MPa or less. [2] Laminated glass according to [1], wherein when a carbide indenter weighing 1.0 g, with a tip angle of 120 degrees and a tip radius of curvature of 0.2 mm is struck perpendicularly to the surface of the first glass plate side of the laminated glass at a speed of 40 km / h, no cracks are generated starting from the second main surface of the first glass plate. [3] Laminated glass according to [1] or [2], wherein the surface strength of the second main surface is 290 MPa or less. [4] The laminated glass according to [1] or [2], wherein the surface strength of the second main surface is 280 MPa or less. [5] The laminated glass according to [1] or [2], wherein the surface strength of the second main surface is 270 MPa or less. [6] The laminated glass according to any one of [1] to [5], wherein the maximum height Sz of the second main surface is 0.01 to 5.00 μm. [7] The laminated glass according to any one of [1] to [6], wherein the haze value is 3.0 or less. [8] The laminated glass according to any one of [1] to [7], wherein the average scratch depth of the second main surface is 1 to 20 μm. [9] The laminated glass according to any one of [1] to [8], wherein when the end face of the laminated glass is processed into a C-chamfer shape (C0.1, angle 45°) using an electroplated grinding wheel of #230 at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min, the average size of the chips generated at the boundary between the first main surface or the second main surface and the end face is 40 μm or less.

[10] The laminated glass according to any one of [1] to [9], wherein when the end face of the laminated glass is processed into a C-chamfer shape (C0.1, angle 45°) using an electroplated grinding wheel of #230 at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min, the average size of the chips generated at the boundary between the third main surface or the fourth main surface and the end face is 40 μm or less.

[11] The laminated glass according to any one of [1] to

[10] , wherein the thickness of the first glass plate is 2.3 to 5.0 mm and the thickness of the second glass plate is 0.5 to 2.0 mm.

[12] The fracture toughness value K of the first glass plate. ＩＣ 0.7 MPa·m １／２ The laminated glass according to any one of [1] to

[11] above.

[13] The laminated glass according to any one of [1] to

[12] above, wherein the Young's modulus of the first glass plate is 60 GPa or more.

[14] The density of the first glass plate and the second glass plate is 2.2 to 2.8 g / cm³ ３ A laminated glass according to any one of [1] to

[13] above.

[15] A laminated glass according to any one of [1] to

[14] above, wherein the Poisson's ratio of the first glass plate and the second glass plate is 0.18 to 0.27.

[16] A laminated glass according to any one of [1] to

[15] above, wherein the glass transition temperature of the first glass plate is 700°C or less.

[17] At least one of the first glass plate and the second glass plate has a mass percentage on an oxide basis of 55 ≤ SiO ２ ≤85 0 ≤Al ２ O ３ ≤25 0 ≤B ２ O ３ ≤20 0 ≤MgO ≤15 0 ≤CaO ≤15 0 ≤SrO ≤10 0 ≤BaO ≤10 0 ≤ZnO ≤10 0 ≤Li ２ O ≤ 5 0 ≤ Na ２ O ≤ 20 0 ≤ K ２ O ≤ 10 0 ≤ Fe ２ O ３Laminated glass according to any one of [1] to

[16] , including ≤ 1.

[18] A method for manufacturing laminated glass according to any one of [1] to

[17] , comprising damaging the second main surface of a first glass plate having a first main surface and a second main surface facing the first main surface by wet blasting, sandblasting, and sandpaper, and stacking the first glass plate, an interlayer, and a second glass plate having a third main surface and a fourth main surface facing the third main surface in this order such that the second main surface of the first glass plate and the third main surface of the second glass plate face each other.

[0116] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0117] <Preparation of Laminated Glass> Laminated glass of Examples 1 to 13 was manufactured using the following procedure. Examples 1 to 11 are examples, and Examples 12 and 13 are comparative examples. (Example 1) [First Glass Plate] Raw materials were placed in a platinum crucible and melted at 1650°C for 3 hours to obtain molten glass with the glass composition (unit: mass%) shown in Glass 1 of Table 1. The molten glass was poured onto a carbon plate and slowly cooled. Both sides of the obtained plate-shaped glass were polished to obtain a plate-shaped first glass plate with a thickness of 2.6 mm, having a first main surface and a second main surface facing the first main surface. The second main surface of the first glass plate was roughened by wet blasting. [Second Glass Plate] Raw materials were placed in a platinum crucible and melted at 1650°C for 3 hours to obtain molten glass with the glass composition (unit: mass%) shown in Glass 1 of Table 1. The molten glass was poured onto a carbon plate and slowly cooled. The obtained plate-shaped glass was polished on both sides to obtain a second plate-shaped glass plate with a thickness of 1.3 mm, having a third main surface and a fourth main surface facing the third main surface. [Interlayer] A polyvinyl butyral with a thickness of 0.76 mm was used as the interlayer. [Laminated glass] The first glass plate, the interlayer, and the second glass plate were stacked in this order so that the second main surface of the first glass plate and the third main surface of the second glass plate faced each other, and the laminated glass of Example 1 was produced by pressing the layers together using an autoclave (1 MPa, 130°C, 3 hours).

[0118] (Examples 2 to 11, 13) Laminated glass panels for Examples 2 to 11 and 13 were manufactured in the same manner as in Example 1, except that the types and thicknesses of the first and second glass panels were changed as shown in Tables 1 and 2.

[0119] (Example 12) The types and thicknesses of the first and second glass plates were changed as shown in Tables 1 and 2, and the laminated glass of Example 12 was manufactured in the same manner as in Example 1. However, in Example 12, no damage was made to the first glass plate.

[0120] The method for determining the values ​​shown in Tables 1 and 2 is as follows: (1) Glass transition temperature Tg The glass transition temperature Tg was measured using a differential thermal expander (TMA) in accordance with JIS R3103-3:2001.

[0121] (2) Average linear expansion coefficient from 50°C to 350°C (CTE_50-350°C) The average linear expansion coefficient from 50°C to 350°C was measured using a differential thermal expander (TMA) in accordance with JIS R3102:1995.

[0122] (3) Density r The density r was measured by the Archimedes method on a 20g glass block, free of bubbles, cut from a glass plate.

[0123] (4) Young's modulus E, shear modulus G, and Poisson's ratio v Young's modulus E, shear modulus G, and Poisson's ratio v were measured at 25°C using the ultrasonic pulse method (Olympus, DL35) in accordance with JIS R1602:1995 "Test method for the elastic modulus of fine ceramics".

[0124] (5) E / r E / r is obtained by rounding the value obtained by dividing Young's modulus E by density r, which was measured using the above method, to the nearest integer.

[0125] (6) Fracture toughness value (K ＩＣ The measurement was performed using the Single-Edge-Precracked-Beam method (SEPB method) based on JIS R1607:2015 "Test Method for Fracture Toughness of Fine Ceramics".

[0126] (7) Average value of chipping size The average value of chipping size on the end face of the first glass plate was calculated by measuring the size of chipping that occurred at the boundary between the first or second main surface and the end face when the end face of each example of laminated glass was processed into a C-chamfer shape (C0.1, angle 45°) using a #230 electroplated grinding wheel at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min, and calculating the average value. The average value of chipping size on the end face of the second glass plate was calculated by measuring the size of chipping that occurred at the boundary between the third or fourth main surface and the end face when the end face of each example of laminated glass was processed into a C-chamfer shape (C0.1, angle 45°) using a #230 electroplated grinding wheel at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min, and calculating the average value.

[0127] (8) Average scratch depth of the second main surface of the first glass plate First, laminated glass of each example, with a size of 50 mm square, was prepared, and a lower ring with a diameter of 30 mm was placed in the center of the fourth main surface of the second glass plate. An upper ring with a diameter of 10 mm was placed in the center of the first main surface of the first glass plate, and a load was applied to the laminated glass at a displacement rate of 1 mm / min until the first glass plate broke. The fracture surface of the second main surface of the first glass plate was observed, and the scratch depth of the second main surface of the first glass plate was measured. Ten samples were measured, and the average value of their scratch depths was defined as the average scratch depth c. Glass that broke within the upper ring in a plan view was considered to have been correctly evaluated.

[0128] (9) RoR (Ring-on-Ring) Strength Using the average scratch depth c of the second main surface of the first glass plate obtained in (8) above, the fracture stress σ is calculated from the following Griffiths formula. ｆ The (MPa) value was calculated and used as the surface strength of the second main surface.

[0129]

[0130] (K in the above formula) ＩＣ This is the fracture toughness value of glass (MPa·m). １／２ ), Y is a shape factor of 1.78, σ ｆ This is the fracture stress (MPa).

[0131] (10) Haze value was measured using a haze meter (HZ-V3).

[0132] (11) Evaluation of Pedestrian Protection Performance Pedestrian protection performance was evaluated using the following method. It was found that pedestrian protection performance correlates with the surface strength in the RoR test. In this invention, products with an RoR strength (breaking stress) of less than 300 MPa were considered to have excellent pedestrian protection performance. Evaluation A is considered a pass, and evaluation B is considered a fail. A: Breaking strength in the RoR test is less than 300 MPa B: Breaking strength in the RoR test is 300 MPa or more

[0133] (11) Evaluation of resistance to flying debris cracks The resistance to flying debris cracks was evaluated using the following method. A carbide indenter weighing 1.0 g, with a tip angle of 120 degrees and a tip radius of curvature of 0.2 mm, was struck perpendicularly to the surface of the first glass plate (outer plate) of the laminated glass at a speed of 40 km / h. The evaluation was based on whether or not a crack originating from the second main surface of the first glass plate occurred. Evaluation A is a pass, and evaluation B is a fail. A: No crack originating from the second main surface B: Crack originating from the second main surface occurs

[0134] The results are shown in Tables 1 and 2.

[0135]

[0136]

[0137] In Examples 1 to 11, the laminated glass had a first glass plate with a thickness greater than that of the second glass plate, and the surface strength of the second main surface measured in the ring-on-ring test was 300 MPa or less, resulting in excellent pedestrian protection performance and resistance to flying debris breakage. On the other hand, the laminated glass in Example 12 had a surface strength exceeding 300 MPa measured in the ring-on-ring test, resulting in inferior pedestrian protection performance. Furthermore, the laminated glass in Example 13 had the same thickness as the first glass plate, resulting in inferior resistance to flying debris breakage.

[0138] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-155113 filed on September 9, 2024, the contents of which are incorporated herein by reference.

[0139] 10 Laminated glass 11 First glass plate 12 Second glass plate 13 Interlayer 20 Indenter 100 Automobile 110 Aperture 120 Housing 150 Rearview mirror 201 Millimeter-wave radar 202 Stereo camera 300 Radio waves S1 First main surface S2 Second main surface S3 Third main surface S4 Fourth main surface

Claims

1. Laminated glass comprising: a first glass plate having a first main surface and a second main surface facing the first main surface; a second glass plate having a third main surface and a fourth main surface facing the third main surface; and an interlayer sandwiched between the second main surface of the first glass plate and the third main surface of the second glass plate, wherein the thickness of the first glass plate is greater than the thickness of the second glass plate, and the surface strength of the second main surface measured by a ring-on-ring test is 300 MPa or less.

2. The laminated glass according to claim 1, wherein when a superhard indenter weighing 1.0 g, with a tip angle of 120 degrees and a tip radius of curvature of 0.2 mm is struck perpendicularly to the surface of the first glass plate of the laminated glass at a speed of 40 km / h, no cracks are generated in the second main surface of the first glass plate.

3. The laminated glass according to claim 1 or 2, wherein the surface strength of the second main surface is 290 MPa or less.

4. The laminated glass according to claim 1 or 2, wherein the surface strength of the second main surface is 280 MPa or less.

5. The laminated glass according to claim 1 or 2, wherein the surface strength of the second main surface is 270 MPa or less.

6. The laminated glass according to claim 1 or 2, wherein the maximum height Sz of the second main surface is 0.01 to 5.00 μm.

7. The laminated glass according to claim 1 or 2, wherein the haze value is 3.0 or less.

8. The laminated glass according to claim 1 or 2, wherein the average scratch depth of the second main surface is 1 to 20 μm.

9. The laminated glass according to claim 1 or 2, wherein when the end face of the laminated glass is processed into a C-chamfer shape (C0.1, angle 45°) using an electroplated grinding wheel of #230 at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min, the average size of the chipping that occurs at the boundary between the first main surface or the second main surface and the end face is 40 μm or less.

10. The laminated glass according to claim 1 or 2, wherein when the end face of the laminated glass is processed into a C-chamfer shape (C0.1, angle 45°) using an electroplated grinding wheel of #230 at a grinding wheel rotation speed of 10,000 rpm and a feed rate of 200 mm / min, the average size of the chipping that occurs at the boundary between the third main surface or the fourth main surface and the end face is 40 μm or less.

11. The laminated glass according to claim 1 or 2, wherein the thickness of the first glass plate is 2.3 to 5.0 mm and the thickness of the second glass plate is 0.5 to 2.0 mm.

12. Fracture toughness value K of the first glass plate. ＩＣ 0.7 MPa·m １／２ The laminated glass according to claim 1 or 2.

13. The laminated glass according to claim 1 or 2, wherein the Young's modulus of the first glass plate is 60 GPa or more.

14. The densities of the first glass plate and the second glass plate are 2.2 to 2.8 g / cm³. ３ The laminated glass according to claim 1 or 2.

15. The laminated glass according to claim 1 or 2, wherein the Poisson's ratio of the first glass plate and the second glass plate is 0.18 to 0.

27.

16. The laminated glass according to claim 1 or 2, wherein the glass transition temperature of the first glass plate is 700°C or less.

17. At least one of the first glass plate and the second glass plate contains, in terms of mass% based on oxides, 55 ≦ SiO ２ ≦ 85, 0 ≦ Al ２ O ３ ≦ 25, 0 ≦ B ２ O ３ ≦ 20, 0 ≦ MgO ≦ 15, 0 ≦ CaO ≦ 15, 0 ≦ SrO ≦ 10, 0 ≦ BaO ≦ 10, 0 ≦ ZnO ≦ 10, 0 ≦ Li ２ O ≦ 5, 0 ≦ Na ２ O ≦ 20, 0 ≦ K ２ O ≦ 10, 0 ≦ Fe ２ O ３ ≦ 1, and the laminated glass according to claim 1 or 2.

18. A method for manufacturing laminated glass according to claim 1 or 2, comprising damaging the second main surface of a first glass plate having a first main surface and a second main surface facing the first main surface by wet blasting, sandblasting, and sandpaper, and stacking the first glass plate, an interlayer, and a second glass plate having a third main surface and a fourth main surface facing the third main surface in this order such that the second main surface of the first glass plate and the third main surface of the second glass plate face each other.

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