Laminated glass

Abstract

The present invention provides a laminated glass which has excellent strength characteristics and excellent bending characteristics in a large area. The laminated glass is obtained by laminating a first glass and a second glass by means of an intermediate film. The thickness of the first glass is thicker than the thickness of the second glass by 1 mm or more, and a parameter X expressed by formula (1) X = X1 - X2(X1 = t1(PaA1,a + PbA1,b + PcA1,c), X2 = t2(PaA2,a + PbA2,b + PcA2,c)) is 0 or more. In formula (1), t1, t2, Pa, Pb, Pc, A1,a, A1,b, A1,c, A2,a, A2,b, and A2,c are as defined in the description.

Description

Laminated glass

[0001] The present invention relates to laminated glass.

[0002] As automobiles become more sophisticated, such as with autonomous driving technology, there are an increasing number of cases where sensor devices that aggregate multiple sensors, such as monochrome cameras and millimeter-wave radar, are installed on the inside of the windshield (WS). As a result, the windshield is required to act as a cover glass for the sensor devices. In other words, to ensure the reliability of the sensors, the windshield must have high strength characteristics.

[0003] Furthermore, in recent years, due to environmental considerations, automobiles without internal combustion engines (ICEs), such as electric vehicles (EVs), have become popular in Europe and the United States. Because the center of gravity of electric vehicles is lower than that of internal combustion engine vehicles, designs that use large, deeply curved glass in the windshield and roof, which increases the glass area, are preferred from a design perspective.

[0004] Laminated glass having two glass sheets and an interlayer film provided therebetween is widely used as glass for automobiles, and various studies have been conducted on it. For example, Patent Document 1 discloses laminated glass in which an outer glass sheet having a convex first surface and a concave second surface and an inner glass sheet having a convex third surface and a concave fourth surface are bonded together via an interlayer film. Patent Document 2 discloses curved laminated glass for window glass, which includes a thick glass sheet and a thin glass sheet that is thinner than the thick glass sheet, the thin glass sheet having a thickness of 0.1 to 1.6 mm and a softening point of the thin glass sheet that is 10°C or higher than the softening point of the thick glass sheet.

[0005] International Publication No. 2017 / 110782 Japanese Patent Application Laid-Open No. 2019-073423

[0006] When forming a curved laminated glass, it is economical to stack two glass sheets on top of each other, place them on a ring mold, and bend them simultaneously. To increase the strength of laminated glass, it is preferable for the ratio of the outer sheet thickness to the total thickness to be large. However, if the thickness difference between the outer and inner sheets is large, bending becomes difficult. Here, the outer sheet is the glass located on the convex side of the curved laminated glass. Achieving both the bending properties and the strength properties of the glass over a large area of ​​laminated glass for use in windshields and roofs is extremely difficult in terms of stabilizing quality, and it has been difficult to obtain good quality products.

[0007] Therefore, an object of the present invention is to provide a laminated glass having excellent bending properties and strength properties over a large area.

[0008] One embodiment of the present invention relates to a laminated glass in which a first glass sheet and a second glass sheet are laminated together with an interlayer film, in which the thickness of the first glass sheet is at least 1 mm thicker than the thickness of the second glass sheet, and a parameter X represented by the following formula (1) is at least 0:

[0009]

[0010] (In formula (1), X １ is expressed by the following formula (2), and X ２ is expressed by the following formula (3):

[0011]

[0012] (In formulas (2) and (3), t １ is the thickness (mm) of the first glass, and t ２ is the thickness (mm) of the second glass, and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A, and P ｂis the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A １，ｂ is the average absorbance of the first glass per mm in the wavelength band B, and A ２，ｂ is the average absorbance of the second glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A １，ｃ is the average absorbance of the first glass per mm in the wavelength band C, and A ２，ｃ is the average absorbance of the second glass per mm in the wavelength band C.

[0013] According to the present invention, it is possible to provide laminated glass that has excellent bending properties and strength properties over a large area.

[0014] Fig. 1 is a cross-sectional view of an example of laminated glass according to an embodiment of the present invention. Fig. 2 is a schematic diagram of an indenter used in a collision test. Fig. 3 is a conceptual diagram showing a state in which laminated glass according to an embodiment of the present invention is used as a window glass for an automobile. Fig. 4 is a partial perspective view showing an enlarged view of part S in the automobile shown in Fig. 3. Fig. 5 is a cross-sectional view taken along line Y-Y in Fig. 4.

[0015] Hereinafter, embodiments of the present invention will be described in detail. 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. The embodiments shown in the drawings are schematic to clearly explain the present invention, and do not necessarily accurately represent the size or scale of an actual product. In this specification, "mass" is synonymous with "weight."

[0016] [Laminated Glass] A laminated glass according to an embodiment of the present invention (hereinafter also referred to as "the present embodiment") is a laminated glass in which a first glass sheet and a second glass sheet are laminated together with an interlayer film, characterized in that the thickness of the first glass sheet is at least 1 mm thicker than the thickness of the second glass sheet, and a parameter X expressed by the following formula (1) is at least 0.

[0017]

[0018] (In formula (1), X １ is expressed by the following formula (2), and X ２ is expressed by the following formula (3):

[0019]

[0020] (In formulas (2) and (3), t １ is the thickness (mm) of the first glass, and t ２ is the thickness (mm) of the second glass, and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A, and P ｂ is the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A １，ｂ is the average absorbance of the first glass per mm in the wavelength band B, and A ２，ｂ is the average absorbance of the second glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A １，ｃ is the average absorbance of the first glass per mm in the wavelength band C, and A ２，ｃ is the average absorbance of the second glass per mm in the wavelength band C.

[0021] Infrared heating may be used to heat laminated glass during molding, and it is important that the infrared rays are selectively absorbed by the thicker of the two glass sheets that make up the laminated glass (the first glass of the laminated glass of this embodiment). When bending a laminated glass for use as an automobile windshield or the like, the laminated glass is processed so that the surface of the thicker first glass is convex, with the first glass facing the outside of the automobile. For example, the laminated glass is placed on a forming mold with the first glass facing downward, and the forming mold is passed through a heating furnace to be heated by infrared rays, thereby curving the laminated glass under its own weight. Because heat rays are irradiated from the thinner second glass side, it is important to design the second glass to have higher transmittance during heating. As a result of extensive research and development, the present inventors have discovered that by controlling the near-infrared transmittance characteristics of the outer and inner sheets of laminated glass, it is possible to form a laminated glass having a large area (specifically, a main surface area of ​​0.9 m2). ２ It has been found that this makes it possible to achieve both bending properties and strength properties in a bending process (such as the above). By adopting the configuration of this embodiment described above, even when bending is performed so that the first pane of glass is curved, heat ray energy can be efficiently absorbed by the first pane of glass, reducing uneven heating in the laminated glass. This reduces the thermal stress applied to the laminated glass, making it less likely to break even in large-area panes, and improving bending properties. Hereinafter, the laminated glass according to this embodiment will be described with reference to FIG. 1.

[0022] FIG. 1 is a diagram showing an example of laminated glass 10 according to this embodiment. The laminated glass 10 includes a first glass sheet 11, a second glass sheet 12, and an interlayer film 13 sandwiched between the first glass sheet 11 and the second glass sheet 12. The first glass sheet 11 has a first main surface S1 that is one of its main surfaces and a second main surface S2 that is the other main surface facing the first main surface S1. The second glass sheet 12 has a third main surface S3 that is one of its main surfaces and a fourth main surface S4 that is the other main surface facing the third main surface S3. The interlayer film 13 is sandwiched between the second main surface S2 of the first glass sheet 11 and the third main surface S3 of the second glass sheet 12.

[0023] (Thickness of First Glass and Second Glass) In the laminated glass 10 according to this embodiment, the thickness of the first glass 11 is at least 1 mm thicker than the thickness of the second glass 12. The thickness of the first glass 11 is at least 1 mm thicker than the thickness of the second glass 12, resulting in excellent impact resistance against flying objects such as pebbles. This is because, when the laminated glass 10 is used in an automobile with the first glass 11 on the exterior side of the automobile, the glass sheet arranged on the exterior side of the automobile is thicker than the glass sheet arranged on the interior side of the automobile, thereby improving the rigidity of the glass sheet on the side where scratches occur, thereby resulting in improved impact resistance of the laminated glass. Furthermore, the thickness of the first glass 11 may be at most 4.5 mm thicker than the thickness of the second glass 12. In this specification, the thickness of the glass sheet refers to the average thickness of the glass measured using a constant pressure thickness gauge.

[0024] The thickness of the first glass 11 is preferably 2.3 to 5.0 mm. When the thickness of the first glass 11 is 2.3 mm or more, high impact resistance can be obtained. Furthermore, when the thickness of the first glass 11 is 5.0 mm or less, bending molding is possible. The thickness of the first glass 11 is more preferably 2.4 mm or more, even more preferably 2.6 mm or more, even more preferably 2.8 mm or more, particularly preferably 3.0 mm or more, even more preferably 3.2 mm or more, and most preferably 3.4 mm or more. Furthermore, the thickness of the first glass 11 is more preferably 4.8 mm or less, even more preferably 4.5 mm or less, and particularly preferably 4.2 mm or less.

[0025] The thickness of the second glass sheet 12 is preferably 0.3 to 2.5 mm. When the thickness of the second glass sheet 12 is 0.3 mm or more, the bend formability of the glass can be improved and high strength properties of the laminated glass can be obtained. Furthermore, when the thickness of the second glass sheet 12 is 2.5 mm or less, the strength properties, bend formability, and weight reduction of the laminated glass can be satisfied. The thickness of the second glass sheet 12 is more preferably 0.35 mm or more, even more preferably 0.4 mm or more, particularly preferably 0.5 mm or more, more preferably 2.1 mm or less, even more preferably 2.0 mm or less, and particularly preferably 1.8 mm or less.

[0026] The ratio of the thickness of the first glass 11 to the thickness of the second glass 12 (thickness of the first glass 11 / thickness of the second glass 12) is preferably 1.1 to 17. When the ratio is 1.1 or more, the resistance to flying stones can be improved. Furthermore, when the ratio is 17 or less, the bending formability can be improved. The ratio is more preferably 1.2 or more, even more preferably 1.4 or more, more preferably 15 or less, even more preferably 13 or less, and particularly preferably 10 or less.

[0027] In the laminated glass according to this embodiment, the parameter X represented by the following formula (1) is 0 or more.

[0028]

[0029] In formula (1), X １ is the infrared light absorption parameter of the first glass, and is expressed by the following formula (2), and X ２ is the infrared light absorption parameter of the second glass, and is expressed by the following formula (3).

[0030]

[0031] In formula (2), t １ is the thickness of the first glass (mm), and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and P ｂ is the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A １，ｂ is the average absorbance of the first glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A １，ｃ is the average absorbance of the first glass per mm in the wavelength band C.

[0032] In formula (3), t ２ is the thickness of the second glass (mm), and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A, and P ｂ is the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A ２，ｂ is the average absorbance of the second glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A ２，ｃ is the average absorbance of the second glass per mm in the wavelength band C.

[0033] As shown in the above formula (1), the parameter X represents the difference in the infrared light absorption parameter between the first glass 11 and the second glass 12. In the above formula (2), X １ is the sum of the product of the average radiance at 900 K in accordance with Planck's radiation law in wavelength band A and the average absorbance of the first glass sheet 11 per 1 mm of plate thickness, the product of the average radiance at 900 K in accordance with Planck's radiation law in wavelength band B and the average absorbance of the first glass sheet 11 per 1 mm of plate thickness, and the product of the average radiance at 900 K in accordance with Planck's radiation law in wavelength band C and the average absorbance of the first glass sheet 11 per 1 mm of plate thickness, multiplied by the thickness of the first glass sheet 11, and represents the heat ray energy absorption efficiency of the first glass sheet 11. Similarly, in the above formula (3), X ２represents the heat ray energy absorption efficiency of the second glass sheet 12, calculated by multiplying the sum of the product of the average radiance at 900 K in accordance with Planck's law in wavelength band A and the average absorbance of the second glass sheet 12 per 1 mm of plate thickness, the product of the average radiance at 900 K in accordance with Planck's law in wavelength band B and the average absorbance of the second glass sheet 12 per 1 mm of plate thickness, and the product of the average radiance at 900 K in accordance with Planck's law in wavelength band C and the average absorbance of the second glass sheet 12 per 1 mm of plate thickness, by the thickness of the second glass sheet 12.

[0034] When the parameter X shown in formula (1) is 0 or greater, the heat ray energy absorption efficiency of the first pane 11 is greater than that of the second pane 12. This means that when heat rays, such as infrared heating, are irradiated from the second pane 12, the heat rays are more likely to reach the first pane 11. This allows the heat rays to pass through the second pane 12 and reach the first pane 11 without being excessively absorbed by the second pane 12. This allows the first pane to efficiently absorb heat ray energy, reducing uneven heating in the laminated glass and reducing thermal stress.

[0035] Here, wavelength band A is a wavelength band in which the radiance according to Planck's law is maximum at temperatures higher than 900 K, wavelength band B is a wavelength band in which the radiance according to Planck's law is maximum at 900 K, and wavelength band C is a wavelength band in which the radiance according to Planck's law is maximum at temperatures lower than 900 K. By checking the average radiance and average absorbance of these wavelength bands, the bending forming characteristics of the glass can be evaluated.

[0036] The absorbance indicates the degree of attenuation of the intensity of light irradiated onto a 1 mm thick glass plate, and is expressed as the common logarithm of the ratio of the transmitted light intensity to the incident light intensity, and the average absorbance is the average value of the absorbance in a specified wavelength band.

[0037] From the viewpoint of bendability, the laminated glass 10 according to this embodiment has an X １ is preferably greater than 0, more preferably 0.005 or greater, even more preferably 0.008 or greater, and particularly preferably 0.01 or greater. １is preferably 1.3 or less, more preferably 1.2 or less, even more preferably 1.1 or less, particularly preferably 1.0 or less, and most preferably 0.9 or less. That is, X １ is preferably in the range of greater than 0 and not more than 1.3, and more preferably in the range of 0.005 to 1.3.

[0038] Furthermore, from the viewpoint of bendability, the laminated glass 10 according to this embodiment has an X ２ is preferably 0.35 or less, more preferably 0.34 or less, even more preferably 0.32 or less, and particularly preferably 0.30 or less. ２ is preferably greater than 0, more preferably 0.005 or greater, even more preferably 0.01 or greater, even more preferably 0.02 or greater, and particularly preferably 0.03 or greater. That is, X ２ is preferably in the range of greater than 0 and not greater than 0.35, more preferably in the range of 0.005 to 0.35, and may be in the range of 0.01 to 0.35.

[0039] In the laminated glass 10 according to this embodiment, X is 0 or greater, preferably greater than 0, more preferably 0.01 or greater, even more preferably 0.02 or greater, and particularly preferably 0.03 or greater. From the viewpoints of visible light transmittance and bend formability, X is preferably 1.2 or less, more preferably 1.0 or less, and even more preferably 0.9 or less. That is, X is preferably in the range of 0 to 1.2.

[0040] In the laminated glass 10 according to this embodiment, it is further preferable that the parameter Y represented by the following formula (4) is 0 or greater.

[0041]

[0042] In formula (4), t １ , t ２ , P ａ , A １，ａ and A ２，ａ is the same as above, and t １ is the thickness of the first glass (mm), and t ２ is the thickness of the second glass (mm), and P ａis the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A.

[0043] As shown in the above formula (4), the parameter Y represents the difference in absorption parameter in wavelength band A between the first glass 11 and the second glass 12. When the parameter Y represented by formula (4) is 0 or greater, the formability of the glass can be further improved. The parameter Y is more preferably 0.001 or greater, even more preferably 0.002 or greater, and particularly preferably 0.003 or greater. From the viewpoint of the manufacturing characteristics of the raw glass plate, the parameter Y is preferably 0.05 or less, more preferably 0.045 or less, even more preferably 0.04 or less, and particularly preferably 0.035 or less. That is, the parameter Y is preferably in the range of 0 to 0.05.

[0044] Methods for setting the parameter X and the parameter Y in the laminated glass 10 according to this embodiment within the above ranges include a method for differentiating the colors of the first glass sheet 11 and the second glass sheet 12, and a method for differentiating the β-OH groups of the first glass sheet 11 and the second glass sheet 12 by adjusting the manufacturing atmosphere in the raw glass sheet manufacturing process.

[0045] One way to differentiate the colors of the first glass sheet 11 and the second glass sheet 12 is to make the first glass sheet more colored than the second glass sheet. In other words, the visible light transmittance of the first glass sheet may be lower than the visible light transmittance of the second glass sheet. Specifically, the first glass sheet may be colored glass and the second glass sheet may be colorless and transparent glass. The visible light transmittance is measured in accordance with JIS R 3106:2019.

[0046] One method for making the β-OH of the first glass 11 and the second glass 12 different is to make the β-OH of the first glass larger than that of the second glass. Examples of methods for making the β-OH larger include increasing the dew point temperature of the atmosphere when melting the glass and using electric melting.

[0047] (Chipping Size) In the laminated glass 10 according to this embodiment, the average size of chippings occurring at the boundary between the first main surface S1, which is one of the main surfaces of the first glass 11, or the second main surface S2, which is the other main surface opposite the first main surface S1, and the edge of the first glass 11 (hereinafter also referred to as "chippings on the edge surface of the first glass 11") is preferably 40 μm or less. The presence of chippings on the edge surface of the glass leads to cracking defects. Having an average chipping size on the edge surface of the first glass 11 of 40 μm or less improves edge workability and makes the glass less likely to break, thereby improving the strength of the glass. The average chipping size on the edge surface of the first glass 11 is more preferably 37 μm or less, even more preferably 36 μm or less, and particularly preferably 35 μm or less. The average chipping size on the edge surface of the first glass 11 in the laminated glass 10 according to this embodiment may be 10 μm or more. That is, the average size of chipping on the end face of the first glass 11 is preferably in the range of 10 to 40 μm.

[0048] Here, in the laminated glass 10 according to this embodiment, chipping occurring at the boundary between the first main surface S1 or the second main surface S2 of the first glass 11 and the edge of the first glass 11 (chipping at the edge of the first glass 11) refers to chipping occurring at the boundary between the first main surface S1 or the second main surface S2 and the edge of the first glass 11 when the edge of the laminated glass 10 is processed into a C-chamfered 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-chamfered shape means that the corner of the edge of the laminated glass 10 is cut off by 0.1 mm at an angle of 45° relative to the edge.

[0049] In order to set the average size of chipping on the edge surface of the first glass sheet 11 in the laminated glass 10 according to this embodiment within the above range, for example, methods can be used to improve the mechanical properties of the glass, slow down the edge surface processing speed, or increase the fictive temperature of the glass.

[0050] Furthermore, in the laminated glass 10 according to this embodiment, the average size of chipping occurring at the boundary between the third main surface S3, which is one of the main surfaces of the second glass pane 12, or the fourth main surface S4, which is the other main surface opposite the third main surface S3, and the edge of the second glass pane 12 (hereinafter also referred to as "chipping on the edge surface of the second glass pane 12") is preferably 35 μm or less. Having an average size of chipping on the edge surface of the second glass pane 12 of 35 μm or less improves the strength of the glass, thereby reducing cracking during the manufacturing process and improving the strength of the laminated glass as a whole. The average size of chipping on the edge surface of the second glass pane 12 is more preferably 33 μm or less, even more preferably 32 μm or less, and particularly preferably 30 μm or less. From the viewpoint of glass productivity, the average size of chipping on the edge surface of the second glass pane 12 in the laminated glass 10 according to this embodiment is more preferably 10 μm or more, even more preferably 11 μm or more, and particularly preferably 12 μm or more. That is, the average size of chipping on the end face of the second glass 12 is preferably in the range of 10 to 35 μm.

[0051] Here, in the laminated glass 10 according to this embodiment, chipping occurring at the boundary between the third main surface S3 or fourth main surface S4 of the second glass 12 and the edge surface of the second glass 12 (chipping at the edge surface of the second glass 12) refers to chipping occurring at the boundary between the third main surface S3 or fourth main surface S4 and the edge surface of the second glass 12 when the edge surface of the laminated glass 10 is processed into a C-chamfered 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.

[0052] In order to keep the average size of chipping on the edge surface of the second glass 12 in the laminated glass 10 according to this embodiment within the above range, for example, a method of reducing the edge surface processing speed can be mentioned.

[0053] (Fracture toughness value) The fracture toughness value K of the first glass 11 in the laminated glass 10 according to this embodiment ＩＣ is 0.70 MPa m １／２ The fracture toughness value K of the first glass 11 is preferably ＩＣ is 0.70 MPa m １／２ By satisfying the above, not only can high resistance to flying stones be achieved, but also thermal cracking caused by uneven heat distribution during the manufacturing process can be reduced. ＩＣ is 0.71 MPa m １／２ More preferably, 0.72 MPa m １／２ More preferably, 0.73 MPa m １／２ The above is particularly preferable. ＩＣ is 1.0 MPa m from the viewpoint of the manufacturing characteristics of the raw plate. １／２ Preferably, 0.95 MPa m or less １／２ More preferably, 0.93 MPa m or less １／２ More preferably, the fracture toughness value K of the first glass 11 is: ＩＣ is 0.70 to 1.0 MPa m １／２ The range is preferred.

[0054] The fracture toughness value K of the second glass 12 in the laminated glass 10 according to this embodiment ＩＣ is 0.70 MPa m １／２ The fracture toughness value K of the second glass 12 is preferably equal to or greater than 100%. ＩＣ is 0.70 MPa m １／２ By satisfying the above, high strength characteristics can be achieved. ＩＣ is 0.71 MPa m １／２ More preferably, 0.72 MPa m １／２ More preferably, 0.73 MPa m １／２ The above is particularly preferable. ＩＣ is 1.0 MPa m from the viewpoint of the manufacturing characteristics of the glass raw material plate. １／２ Preferably, 0.95 MPa m or less １／２ More preferably, 0.93 MPa m or less１／２ More preferably, the fracture toughness value K of the second glass 12 is: ＩＣ is 0.70 to 1.0 MPa m １／２ The range is preferred.

[0055] The fracture toughness value K of the first glass sheet 11 and the second glass sheet 12 in the laminated glass 10 according to this embodiment ＩＣ In order to make it fall within the above range, for example, SiO ２ The method for adjusting the content of the alkali metal component is to adjust the proportion of the alkali metal component having a small atomic number, or to adjust the proportion of the alkali metal component having a small atomic number. ２ Since is a component that forms a network structure, increasing the content strengthens the glass structure, thereby improving fracture toughness. Furthermore, the smaller the atomic number of the alkaline earth metal component, the higher the Young's modulus, and as a result, the higher the fracture toughness. The smaller the atomic number of the alkali metal component, the same tendency as that of the alkaline earth metal component is observed.

[0056] Fracture toughness value K ＩＣ (MPa m １／２ ) is Young's modulus E (GPa), surface fracture energy γ (J / m ２ ) and Poisson's ratio ν (unitless) using the following formula:

[0057]

[0058] Furthermore, the fracture toughness values ​​K of the first glass pane 11 and the second glass pane 12 in the laminated glass 10 according to this embodiment are ＩＣ is measured using a pre-crack introduction fracture test method (SEPB method: Single-Edge-Precracked-Beam method) based on JIS R1607:2015 "Fracture toughness test method for fine ceramics".

[0059] (Young's Modulus) The Young's modulus E of the first glass 11 in the laminated glass 10 according to this embodiment is preferably 60 GPa or more. Having a Young's modulus E of 60 GPa or more enables the realization of high mechanical properties. The Young's modulus E of the first glass 11 is more preferably 61 GPa or more, even more preferably 62 GPa or more, even more preferably 64 GPa or more, particularly preferably 68 GPa or more, and most preferably 70 GPa or more. The Young's modulus E of the first glass 11 in the laminated glass 10 according to this embodiment is preferably 100 GPa or less, from the viewpoints of the manufacturing characteristics of the raw glass and thermal stress generated due to temperature non-uniformity during heating. The Young's modulus E of the first glass 11 is more preferably 97 GPa or less, even more preferably 95 GPa or less, even more preferably 93 GPa or less, and particularly preferably 90 GPa or less. That is, the Young's modulus E of the first glass 11 is preferably in the range of 60 to 100 GPa.

[0060] The Young's modulus E of the second glass 12 in the laminated glass 10 according to this embodiment is preferably 60 GPa or more. Having a Young's modulus E of 60 GPa or more enables the realization of high mechanical properties. The Young's modulus E of the second glass 12 is more preferably 61 GPa or more, even more preferably 62 GPa or more, even more preferably 64 GPa or more, particularly preferably 68 GPa or more, and most preferably 70 GPa or more. The Young's modulus E of the second glass 12 in the laminated glass 10 according to this embodiment is preferably 100 GPa or less, from the viewpoints of the manufacturing characteristics of the raw glass and thermal stress generated due to temperature non-uniformity during heating. The Young's modulus E of the second glass 12 is more preferably 97 GPa or less, even more preferably 95 GPa or less, even more preferably 93 GPa or less, and particularly preferably 90 GPa or less. That is, the Young's modulus E of the second glass 12 is preferably in the range of 60 to 100 GPa.

[0061] In order to set the Young's modulus within the above range, the type and amount of alkaline earth metal and alkali metal are adjusted, and MgO and Li ２ Increase the O content, ２ O ３ , TiO ２ , ZrO ２The Young's modulus can be measured by an ultrasonic pulse method based on JIS R1602:1995 "Testing method for elastic modulus of fine ceramics."

[0062] (Density) The density r of the first glass 11 and the second glass 12 in the laminated glass 10 according to this embodiment is 2.1 to 2.8 g / cm ３ When the density r is in the above range, the glass has good strength characteristics and bend formability, and the vehicle weight can be reduced, resulting in excellent product characteristics. The density r of the first glass 11 and the second glass 12 is 2.1 g / cm ３ More than 2.15 g / cm ３ More preferably, 2.8 g / cm ３ Preferably, 2.7 g / cm or less ３ The following is more preferred:

[0063] The density of the first glass sheet 11 and the second glass sheet 12 in the laminated glass 10 according to this embodiment is measured by the Archimedes method using a glass block of about 20 g containing no bubbles cut out from a glass plate.

[0064] (E / r) In the laminated glass 10 according to this embodiment, the value E / r obtained by dividing the Young's modulus E by the density r of each of the first glass pane 11 and the second glass pane 12 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. E / r of the first glass pane 11 and the second glass pane 12 is more preferably 26 or more, even more preferably 27 or more, and more preferably 38 or less, even more preferably 36 or less.

[0065] (Poisson's ratio) The Poisson's ratio of each of the first glass sheet 11 and the second glass sheet 12 in the laminated glass 10 according to this embodiment is preferably 0.18 to 0.27. Having a Poisson's ratio within this range results in excellent strength characteristics and bend formability. The Poisson's ratio of the first glass sheet 11 and the second glass sheet 12 is more preferably 0.19 or more, even more preferably 0.20 or more, and is more preferably 0.265 or less, even more preferably 0.26 or less.

[0066] The Poisson's ratio of the first glass sheet 11 and the second glass sheet 12 in the laminated glass 10 according to this embodiment can be measured by an ultrasonic pulse method based on JIS R1602:1995 "Testing method for elastic modulus of fine ceramics."

[0067] (Glass transition temperature) The glass transition temperature Tg of the first glass pane 11 in the laminated glass 10 according to this embodiment is preferably 700°C or lower. When the glass transition temperature Tg of the first glass pane 11 is 700°C or lower, the bend formability is excellent. The glass transition temperature Tg of the first glass pane 11 is more preferably 680°C or lower, even more preferably 660°C or lower, and particularly preferably 650°C or lower. In view of the weather resistance and stability of the glass, the glass transition temperature Tg of the first glass pane 11 in the laminated glass 10 according to this embodiment is preferably 420°C or higher, more preferably 450°C or higher, and even more preferably 470°C or higher. That is, the glass transition temperature Tg of the first glass pane 11 is preferably in the range of 420 to 700°C.

[0068] The glass transition temperature Tg of the second glass pane 12 in the laminated glass 10 according to this embodiment is preferably 720°C or lower. Having a glass transition temperature Tg of 720°C or lower results in excellent bend formability. The glass transition temperature Tg of the second glass pane 12 is more preferably 700°C or lower, even more preferably 680°C or lower, and particularly preferably 670°C or lower. From the viewpoints of bend formability and glass stability, the glass transition temperature Tg of the second glass pane 12 in the laminated glass 10 according to this embodiment is preferably 450°C or higher, more preferably 470°C or higher, and even more preferably 500°C or higher. That is, the glass transition temperature Tg of the second glass pane 12 is preferably in the range of 450 to 720°C.

[0069] The glass transition temperature Tg can be measured using a differential thermal dilatometer (TMA) in accordance with JIS R3103-3:2001.

[0070] (Average Coefficient of Linear Expansion) The average coefficient of linear expansion (CTE) of the first glass 11 and the second glass 12 in the laminated glass 10 according to this embodiment at 50 to 350°C is 100 × 10 －７ / °C or less. The average linear expansion coefficient is preferably 100 x 10－７ / °C or less, cracking due to heat shock can be suppressed when the laminated glass of this embodiment is used as a window glass for a vehicle. Furthermore, when the laminated glass of this embodiment is used as a curved glass, the difference in thermal expansion due to the difference in thermal history within the surface can be suppressed, and curved glass with good dimensional and surface accuracy can be obtained. －７ / °C or less, and 95 x 10 －７ / °C or less is more preferable, and 92 × 10 －７ / °C or less is more preferable, and 90 x 10 －７ / °C or less. From the viewpoint of suppressing cracking of the black ceramic due to the difference in thermal expansion between the black ceramic printed on the windshield and the black ceramic, the average linear expansion coefficient is preferably 70 x 10 －７ / °C or more. －７ / °C or more, the difference in thermal expansion with the black ceramic is small, and cracking of the black ceramic can be suppressed. －７ / °C or more is more preferable, and 74 x 10 －７ / °C or more is more preferable, and 76 x 10 －７ / °C or more, and 78 x 10 －７ / °C or more is particularly preferred, and 80 x 10 －７ / °C or more is particularly preferred, and 82 x 10 －７ / °C or more. That is, the average linear expansion coefficient of the first glass 11 and the second glass 12 at 50 to 350°C is 70×10 －７ / ℃~100×10 －７ / °C range is preferred.

[0071] In order to set the average linear expansion coefficient within the above range, the SiO ２ Increase the content of R ２ O, RO and Al ２ O ３ The method for adjusting the content of

[0072] The average linear expansion coefficient can be measured using a differential thermal dilatometer (TMA) in accordance with JIS R3102:1995.

[0073] (Resistance to Stone-Flying Breakage) As shown in FIG. 2 , when a super steel indenter 20 weighing 1.0 g, having a tip angle of 120 degrees, and a tip curvature radius of 0.2 mm is collided perpendicularly with the surface of the laminated glass 10 facing the first pane 11 (the first main surface S1 of the first pane 11 in FIG. 1 ) at a speed of 40 km / h, the size of a crack originating from the second main surface S2 of the first pane 11 is preferably less than 8 mm, and more preferably no crack occurs.

[0074] (Composition of First Glass and Second Glass) At least one of the first glass and the second glass in the laminated glass 10 according to this embodiment has a composition, expressed as mass % 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 ３ It is preferred that ≦1.

[0075] The composition range of each component in the first glass or second glass (hereinafter simply referred to as the present glass plate) of this embodiment will be described below. The composition range of each component will be expressed in mass % based on the oxide unless otherwise specified. Furthermore, when a glass is "substantially free" of a component, it means that the component 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.

[0076] SiO in this glass plate ２ The content of SiO is preferably 55% or more and 85% or less. ２ contributes to improving the Young's modulus, making it easier to ensure the strength required for automobile applications, etc. ２If the content of SiO is too low, it becomes difficult to ensure weather resistance, and the average linear expansion coefficient becomes too large, which may cause thermal cracking of the glass plate. ２ If the amount is too large, the viscosity of the glass increases when melted, which may make it difficult to manufacture the glass.

[0077] SiO in this glass plate ２ The content of SiO in the present glass plate is more preferably 57% or more, further preferably 59% or more, and particularly preferably 60% or more. ２ The content is more preferably 82% or less, further preferably 80% or less, and particularly preferably 78% or less.

[0078] Al in this glass plate ２ O ３ The content of Al is preferably 0% or more and 25% or less. ２ O ３ This contributes to improving the strength and stability of the glass. ２ O ３ When it contains Al ２ O ３ The content of Al is more preferably 0.3% or more, further preferably 0.5% or more, particularly preferably 0.7% or more, and most preferably 1.0% or more. ２ O ３ If the content of Al is too high, the viscosity of the glass increases during melting, which may make it difficult to manufacture the glass. ２ O ３ The content of １１ , T １２ From the viewpoint of keeping T low and facilitating the production of bent glass, it is more preferably 23% or less, further preferably 20% or less, particularly preferably 17% or less, and most preferably 15% or less. １１ is a glass viscosity of 10 １１ indicates the temperature in [dPa s], and T １２ is a glass viscosity of 10 １２ The temperature is shown in [dPa·s].

[0079] B in this glass plate ２ O ３ The content of is preferably 0% or more and 20% or less. ２ O３ This glass plate contributes to improving the glass strength and meltability. ２ O ３ When it contains B ２ O ３ The content is more preferably 1% or more, further preferably 2% or more, particularly preferably 3% or more, and most preferably 5% or more.

[0080] On the other hand, B ２ O ３ If the content of B in the glass plate is too high, the alkali element is likely to volatilize during melting and forming, which may result in a deterioration in glass quality and a decrease in acid resistance and alkali resistance. ２ O ３ The content is more preferably 19% or less, further preferably 18% or less, particularly preferably 17% or less, and most preferably 16% or less.

[0081] In this glass plate, SiO ２ +Al ２ O ３ +B ２ O ３ , i.e., SiO ２ Content and Al ２ O ３ Content and B ２ O ３ The total content may be 65% or more and 97% or less. By setting it in the above range, the temperature T １１ , T １２ This makes it easier to manufacture bent glass. ２ +Al ２ O ３ +B ２ O ３ is more preferably 96% or less, and even more preferably 95% or less. ２ +Al ２ O ３ +B ２ O ３ If the amount is too small, the weather resistance may be reduced. ２ +Al ２ O ３ +B ２ O ３ is more preferably 68% or more, and even more preferably 70% or more.

[0082] The content of MgO in the present glass plate is preferably 0% or more and 15% or less. MgO is a component that promotes the melting of glass raw materials and improves weather resistance and Young's modulus. When the present glass plate contains MgO, the content of MgO is more preferably 0.5% or more, and even more preferably 1.0% or more. Furthermore, if the content of MgO in the present glass plate is 15% or less, devitrification is less likely to occur. The content of MgO in the present 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.

[0083] The CaO content in the present glass plate is preferably 0% or more and 15% or less. When the present 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 meltability of glass raw materials and the formability of bent glass. Furthermore, by setting the CaO content in the present glass plate to 15% or less, an increase in the density of the glass is avoided, and low brittleness and strength are maintained. In order to prevent the glass from becoming brittle, the CaO content in the present glass plate is more preferably 14% or less, even more preferably 13% or less, particularly preferably 12% or less, and most preferably 10% or less.

[0084] The SrO content in the present glass plate is preferably 0% or more and 10% or less. When SrO is contained, it is more preferably 0.1% or more, and even more preferably 0.2% or more. This improves the meltability of glass raw materials and the formability of bent glass. Furthermore, by setting the SrO content in the present glass plate to 10% or less, an increase in the density of the glass is avoided, and low brittleness and strength are maintained. In order to prevent the glass from becoming brittle, the SrO content in the present glass plate is more preferably 8% or less, even more preferably 6% or less, particularly preferably 5% or less, and most preferably substantially no SrO is contained.

[0085] The content of BaO in the present glass plate is preferably 0% or more and 10% or less. BaO is a component that improves the melting property of glass raw materials. When the present glass plate contains BaO, the content of BaO is more preferably 0.1% or more, and even more preferably 0.2% or more. Furthermore, by setting the content of BaO in the present 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 content of BaO in the present glass plate is more preferably 7% or less, even more preferably 5% or less, particularly preferably 3% or less, and most preferably substantially no BaO is contained.

[0086] The ZnO content in the present glass plate is preferably 0% or more and 10% or less. ZnO is a component that improves the melting property of glass raw materials. When ZnO is contained, it is more preferably 0.1% or more, and even more preferably 0.2% or more. Furthermore, by making the ZnO content 10% or less, the devitrification properties of the glass are improved. The ZnO content is more preferably 8% or less, even more preferably 6% or less, particularly preferably 4% or less, and most preferably substantially none.

[0087] Li in this glass plate ２ The content of O is preferably 0% or more and 5% or less. ２ O is a component that improves the meltability of glass, and also makes it easier to increase the Young's modulus, thereby contributing to improving the strength of the glass. ２ By incorporating O, the viscosity of the glass is reduced, and therefore the formability of window glass for vehicles, particularly windshields, etc. is improved. ２ When O is contained, Li ２ The O content is more preferably 0.1% or more, further preferably 0.3% or more, particularly preferably 0.4% or more, and most preferably 0.5% or more. ２ If the content of O is too high, devitrification may occur during glass production, making production difficult. ２ The O content is more preferably 4.5% or less, further preferably 4.3% or less, particularly preferably 4.2% or less, and most preferably 4.0% or less.

[0088] Na in this glass plate ２ The content of O is preferably 0% or more and 20% or less. ２ O is a component that improves the melting property of glass. ２ By including O, the viscosity of the glass is reduced, and therefore the formability of the glass for vehicle window glass, particularly windshield, is improved. ２ When O is contained, Na ２ The O content is more preferably 1% or more, further preferably 1.5% or more, particularly preferably 2.0% or more, and most preferably 2.5% or more. ２ If the amount of O is too large, the average linear expansion coefficient becomes too large, and the glass plate is prone to thermal cracking. ２ The O content is more preferably 19% or less, further preferably 18% or less, particularly preferably 17% or less, and most preferably 15% or less.

[0089] K in this glass plate ２ The content of O is preferably 0% or more and 10% or less. ２ O is a component that improves the melting property of glass. ２ When O is contained, K ２ The O content is more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.3% or more, particularly preferably 0.4% or more, and most preferably 0.5% or more. ２ If the content of O is too high, the average linear expansion coefficient becomes too large, and the glass plate is prone to thermal cracking. ２ The O content is more preferably 9% or less, further preferably 8% or less, and particularly preferably 7% or less.

[0090] Fe in this glass plate ２ O ３ The content of Fe is preferably 0% or more and 1% or less. ２ O ３ can be contained in order to impart heat insulating properties to the glass. ２ O ３ The content of FeO, which is an oxide of divalent iron, and Fe, which is an oxide of trivalent iron ２ O３ This refers to the total amount of iron, including

[0091] The glass plate is Fe ２ O ３ When containing Fe ２ O ３ The content of Fe in the glass plate is more preferably 0.01% or more, further preferably 0.02% or more, even more preferably 0.03% or more, particularly preferably 0.04% or more, and most preferably 0.05% or more. ２ O ３ The content is more preferably 0.9% or less, further preferably 0.8% or less, particularly preferably 0.6% or less.

[0092] The glass plate is made of the above-mentioned 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 The composition may contain components other than those mentioned above (hereinafter also referred to as "other components"), and when other components are contained, the total content thereof is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less.

[0093] 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, MoO ３ , S.O. ３, Cl, F, SnO ２ , Sb ２ O ３ These may be metal ions or oxides. Other components may be contained for various purposes (for example, fining and coloring).

[0094] (β-OH value) In the first glass and the second glass of the present embodiment, when moisture is present in the glass sheet, the adhesion between the glass sheet and the interlayer film is increased. １１ and T １２ This has the effect of lowering the β-OH value, which makes it easier to bend the glass sheet. Therefore, it is preferable that the first glass and the second glass in this embodiment contain a certain amount of moisture. The moisture content in the glass sheet can generally be expressed by a value called the β-OH value.

[0095] In this embodiment, at least one of the first glass and the second glass has a β-OH value of 0.050 mm －１ It is preferable that the thickness is 0.10 mm or more. －１ More preferably, 0.15 mm or more －１ More preferably, 0.20 mm or more －１ The above is particularly preferable. β-OH can be 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 [%] at T Ｂ : Hydroxyl group absorption wave number 3600 cm －１ Minimum transmittance in the vicinity [%]

[0096] On the other hand, if the amount of water in the glass sheet is too large, it may affect the network structure of the glass and reduce the resistance to chipping by stones. －１ Preferably, 0.60 mm or less －１ More preferably, 0.50 mm or less －１ More preferably, 0.40 mm or less－１ The following are particularly preferred:

[0097] (Forming of Glass Sheets) The first glass and the second glass in this embodiment are preferably float glasses formed by, for example, a known float process. In the float process, a molten glass base is floated on a molten metal such as tin, and strict temperature control is performed to form glass with uniform thickness and sheet width, and also to obtain glass with a large area.

[0098] 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.

[0099] The shapes of the first and second glass sheets in this embodiment are not particularly limited, but the area of ​​the main surface is preferably 250,000 mm ２ More than 450,000 mm is preferable. ２ More preferably, 900,000 mm or more ２ The above is even more preferable. When the area of ​​the glass sheet is within the above range, it can be used for various vehicle models. Furthermore, if the area of ​​the glass sheet is too large, the glass sheet becomes difficult to handle, the temperature distribution during heating becomes uneven, and the dimensional accuracy after bending becomes poor, which increases the difficulty of bending. Therefore, the area of ​​the main surface is set to 4,000,000 mm ２ Preferably, less than 3,500,000 mm ２ More preferably, 3,000,000 mm or less ２ The following is even more preferred:

[0100] The first glass sheet and the second glass sheet in this embodiment may be glass sheets that have been subjected to tempering treatment such as air-cooling tempering or chemical tempering, which can increase the strength of the glass sheets.

[0101] Here, air-cooling tempering is a process for forming a compressive stress layer on the glass surface by thermal tempering. Specifically, a uniformly heated glass sheet 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 glass interior. The compressive stress is generated uniformly over the entire glass surface, and a compressive stress layer of uniform depth is formed over the entire glass surface. Thermal tempering is more suitable for tempering thick glass sheets than chemical tempering.

[0102] Chemical strengthening is a process in which alkali metal ions with a small ionic radius (typically Li ions or Na ions) on the glass surface are replaced with alkali metal ions with a larger ionic radius (typically Na ions or K ions) by ion exchange at a temperature below the glass transition point, thereby forming a compressive stress layer on the glass surface. The chemical strengthening process can be carried out by a known method, such as ion exchange. The ion exchange process involves immersing a glass plate in a treatment solution (e.g., potassium nitrate molten salt) and exchanging ions with a small ionic radius (e.g., Na ions) contained in the glass for ions with a large ionic radius (e.g., K ions), thereby generating compressive stress on the glass surface. The magnitude of the compressive stress on the glass plate surface (hereinafter also referred to as 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.

[0103] (Bent Glass) The first glass and the second glass in this embodiment may be bent glass, which may be formed by shaping the flat first glass or the flat second glass into a curved shape by gravity forming, press forming, or the like.

[0104] Bent glass is glass that curves at a predetermined curvature, and may be single-curved glass that curves in only one direction, either up and down or left and right, or double-curved glass that curves in both up and down and left and right directions.

[0105] The minimum radius of curvature of the bent glass is preferably 500 mm or more and 100,000 mm or less. The radius of curvature of the bent glass is calculated by performing a shape simulation on a sample using a laser displacement meter (Dyvoce manufactured by Kohzu Seiki Co., Ltd.) based on the amount of warp inherent to the sample determined by weight deflection correction in a double-sided differential mode, and the radius of curvature is determined from the shape obtained by the simulation.

[0106] In the method for producing bent glass, the flat first glass or second glass is heated and bent to form bent glass. Examples of methods for forming bent glass include a method in which heated glass is placed on a forming mold and pressed from above with a press to bend it. Another method involves placing flat glass on a forming mold having a bending surface corresponding to the desired curved surface, transporting the forming mold in this state into a heating furnace, and heating the glass in the heating furnace to near the glass softening point. According to this forming method, the glass curves along the bending surface of the forming mold due to its own weight as it softens, thereby producing glass with the desired curved surface.

[0107] In this embodiment, bending by the press means is preferred from the viewpoint of improving productivity and improving surface accuracy after forming. The bending method by the press means is not particularly limited, and for example, the method described in International Publication No. 2016 / 093031 can be appropriately adopted. Hereinafter, the bending method by the press means will be described as an example.

[0108] First, the flat-shaped first glass and second glass are transported to a press area by a transport conveyor or the like. Then, in the press area, the flat-shaped first glass and second glass are heated to a temperature at which they can be bent and softened. Here, the bendable temperature is, for example, a temperature at which the glass viscosity is 10 １１ [dPa s] Temperature T １１ The heating may be performed by a heater in a heating furnace during the process of transporting the material to the pressing area on a transport conveyor or the like. １１ The bending time under the condition of maintaining the above condition can be set to, for example, 1 second or more.

[0109] A lower press mold (female mold) and an upper press mold (male mold) are arranged at predetermined positions in the press area, and the upper surface shape of the female mold and the lower surface shape of the male mold correspond to the curved shapes of the first glass and the second glass to be bent in the conveying direction and the perpendicular direction. The female mold can be raised and lowered between a standby position below the conveyor and a press position above it, and after the glass is transferred from the conveyor, the female mold, with the glass placed on it, is raised from a predetermined raised position to a press position above the conveyor, thereby press-forming the glass.

[0110] Next, the press-formed glass is transported to a cooling area by a transport shuttle, etc. In the cooling area, the glass is cooled by blowing cooled air onto it, etc.

[0111] The above steps result in the formation of bent glass. While the above has described bending the first glass and the second glass, the first glass and the second glass may be simultaneously bent to reduce the difference in shape between the first glass and the second glass. When performing such bending, the first glass is placed face down in a forming mold and processed.

[0112] (Interlayer film) The interlayer film 13 according to this embodiment is sandwiched between the first glass pane 11 and the second glass pane 12. By including the interlayer film 13, the laminated glass 10 according to this embodiment can firmly bond the first glass pane 11 and the second glass pane 12 together and can also absorb the impact force when flying fragments collide with the glass panes.

[0113] Various organic resins that are commonly used in conventional laminated glass can be used for the interlayer film 13. 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 hol. Examples of materials that can be used include marl (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), and polyetheretherketone (PEEK). 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.

[0114] From the viewpoints of impact absorption and sound insulation, the thickness of the interlayer film 13 is preferably 0.300 mm or more, more preferably 0.500 mm or more, and even more preferably 0.700 mm or more. Furthermore, from the viewpoint of suppressing a decrease in visible light transmittance, the thickness of the interlayer film 13 is preferably 1.00 mm or less, more preferably 0.900 mm or less, and even more preferably 0.800 mm or less. Furthermore, the thickness of the interlayer film 13 is preferably in the range of 0.300 mm to 1.00 mm, more preferably 0.700 mm to 0.800 mm. The thickness of the interlayer film 13 may be uniform across the entire surface or may vary from location to location as necessary. Note that the thickness of the interlayer film in this specification refers to the thickness calculated by measuring the average thickness of the laminated glass 10 using a constant-pressure thickness gauge and subtracting the average thickness of the first glass pane 11 and the average thickness of the second glass pane 12 from the average thickness of the laminated glass 10.

[0115] 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. The difference in linear expansion coefficient between the interlayer film 13 and the first glass sheet 11 or the second glass sheet 12 may be expressed as the difference between the average linear expansion coefficients in a predetermined temperature range.

[0116] In particular, since 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 within a temperature range equal to or lower than the glass transition point of the resin material. 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 at a predetermined temperature equal to or lower than the glass transition point of the resin material.

[0117] Alternatively, an adhesive layer containing an adhesive may be used as the interlayer film 13. The adhesive is not particularly limited, but an acrylic adhesive, a silicone adhesive, or the like may be used. When the interlayer film 13 is an adhesive layer, a heating step is not required in the process of joining the first glass plate 11 and the second glass plate 12, and therefore the risk of the above-mentioned cracking or warping occurring is reduced.

[0118] (Total Thickness) In the laminated glass 10 of this embodiment, the total thickness of the first glass 11, the second glass 12, and the interlayer film 13 is preferably 2.9 mm or more. A total thickness of 2.9 mm or more maintains the impact resistance and bend formability of the laminated glass. The total thickness is more preferably 3.5 mm or more, and even more preferably 4.0 mm or more. From the viewpoint of ensuring sufficient strength, it is even more preferably 4.1 mm or more, even more preferably 4.2 mm or more, particularly preferably 4.5 mm or more, especially preferably 4.6 mm or more, and most preferably 4.7 mm or more. Furthermore, from the viewpoint of weight reduction, the total thickness may be 8.5 mm or less, preferably 8.0 mm or less, more preferably 7.5 mm or less, even more preferably 6.5 mm or less, even more preferably 6.4 mm or less, particularly preferably 6.3 mm or less, and most preferably 6.2 mm or less. In other words, the total thickness of the laminated glass 10 is preferably in the range of 2.9 to 8.5 mm, and a thickness appropriate for the intended use, size, etc. can be selected.

[0119] (Other Layers) The laminated glass 10 of this embodiment may include layers other than the first glass pane 11, the second glass pane 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 imparts water-repellent properties, hydrophilic properties, anti-fogging properties, or an infrared-reflective film. The location of the other layers is not particularly limited, and the other layers may be provided on the surface of the laminated glass 10, or may be sandwiched between the first glass pane 11, the second glass pane 12, or the interlayer film 13. The laminated glass 10 of this embodiment may also include a black ceramic layer or the like arranged in a strip shape along part or all of its peripheral edge for the purpose of concealing the attachment portion to a frame or the wiring conductors.

[0120] (Method for manufacturing laminated glass) The laminated glass 10 of this embodiment 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 in this order and then subjecting them to a heating and pressurizing process, a laminated glass 10 can be obtained in which the first glass sheet 11 and the second glass sheet 12 are bonded together via the interlayer film 13.

[0121] The method for manufacturing the laminated glass 10 according to this embodiment 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 configured such that the first glass sheet 11 and the second glass sheet 12 are joined together via the interlayer film 13.

[0122] (Vehicle window glass) The laminated glass 10 of this embodiment is suitably used as a vehicle window glass. Hereinafter, an example of using the laminated glass 10 of this embodiment as a vehicle window glass will be described with reference to the drawings. FIG. 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 attached to its surface on the interior side of the vehicle, the housing 120 housing an information device or the like to ensure the driving safety of the vehicle.

[0123] The information device housed in the housing is a device that uses a camera, radar, etc. to prevent rear-end collisions with vehicles ahead, pedestrians, obstacles, etc., and to alert the driver to danger. For example, it is an information receiving device and / or information transmitting device, etc., and includes millimeter-wave radar, stereo cameras, infrared lasers, etc., which send and receive signals. The "signal" refers to electromagnetic waves including millimeter waves, visible light, infrared light, etc.

[0124] 4 is an enlarged partial perspective view of the S portion of the automobile in FIG. 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 housing the information devices is usually attached on the outer side of the vehicle relative to the rearview mirror 150 and on the inner side of the vehicle relative to the laminated glass 10, but may also be attached to other portions.

[0125] 5 is a cross-sectional view taken along line Y-Y in FIG. 4 and perpendicular to the horizontal line. It is preferable that the first glass 11 of the laminated glass 10 be positioned on the vehicle exterior side. This configuration allows for a lightweight, gray-colored windshield with high stone chip resistance and rigidity.

[0126] The present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and modifications and improvements can be made as appropriate. In addition, the material, shape, size, number, and location of each component in the above-described embodiments are arbitrary and not limited as long as the present invention can be achieved.

[0127] As described above, this specification discloses the following: [1] Laminated glass in which a first glass sheet and a second glass sheet are laminated together with an interlayer film, the thickness of the first glass sheet being at least 1 mm thicker than the thickness of the second glass sheet, and the parameter X shown in the following formula (1) being at least 0:

[0128]

[0129] (In formula (1), X １ is expressed by the following formula (2), and X ２ is expressed by the following formula (3):

[0130]

[0131] (In formulas (2) and (3), t １ is the thickness (mm) of the first glass, and t ２ is the thickness (mm) of the second glass, and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A, and P ｂis the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A １，ｂ is the average absorbance of the first glass per mm in the wavelength band B, and A ２，ｂ is the average absorbance of the second glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A １，ｃ is the average absorbance of the first glass per mm in the wavelength band C, and A ２，ｃ is the average absorbance of the second glass per mm in the wavelength band C. [2] The laminated glass according to [1] above, wherein a parameter Y represented by the following formula (4) is 0 or greater:

[0132]

[0133] (In formula (4), t １ , t ２ , P ａ , A １，ａ and A ２，ａ is the same as above.) [3] X in the formula (1) １ [4] The laminated glass according to the above [1] or [2], wherein X in the formula (1) is 0.005 to 1.3. ２ [5] The laminated glass according to the above [3], wherein X in the formula (1) is 0.005 to 0.35. ２[6] The laminated glass according to any one of [1] to [5] above, wherein, when an edge of the laminated glass is processed into a C-chamfered shape (C0.1, angle 45°) using a #230 electroplated grindstone at a grindstone rotation speed of 10,000 rpm and a feed rate of 200 mm / min, the average size of chipping generated at the boundary between one main surface of the first glass and the other main surface opposite to the one main surface of the first glass and the edge of the first glass is 40 μm or less. [7] The laminated glass according to any one of [1] to [6], wherein, when the edge of the laminated glass is processed into a C-chamfered 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, the average size of chipping generated at the boundary between one main surface of the second glass or the other main surface opposite to the one main surface and the edge of the second glass is 35 μm or less. [8] The laminated glass according to any one of [1] to [7], wherein the thickness of the first glass is 2.3 to 5.0 mm, and the thickness of the second glass is 0.3 to 2.5 mm. [9] The first glass has a fracture toughness of 0.70 MPa m １／２

[10] The laminated glass according to any one of [1] to [9], wherein the Young's modulus of the first glass is 60 GPa or more.

[11] The laminated glass according to any one of [1] to [9], wherein the density of the first glass and the second glass is 2.1 to 2.8 g / cm ３

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

[11] above, wherein the Poisson's ratios of the first glass and the second glass are 0.18 to 0.27.

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

[12] above, wherein the glass transition temperature of the first glass is 700°C or lower.

[14] At least one of the first glass and the second glass has a SiO content, expressed in mass% 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 ３ The laminated glass according to any one of [1] to

[13] above, comprising ≦1.

[0134] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0135] <Preparation of Laminated Glass> Laminated glasses of Examples 1 to 13 were prepared according to the following procedure. Examples 1 to 11 are working examples, and Examples 12 and 13 are comparative examples.

[0136] Example 1 [First Glass] Raw materials were placed in a platinum crucible and melted at 1650°C for 3 hours to obtain molten glass, so as to obtain the glass composition (unit: mass%) shown in Glass 1 in 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 3.3 mm thick plate-shaped first glass having a first main surface and a second main surface opposite the first main surface. [Second Glass] Raw materials were placed in a platinum crucible and melted at 1650°C for 3 hours to obtain the glass composition (unit: mass%) shown in Glass 8 in 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 0.7 mm thick plate-shaped second glass having a third main surface and a fourth main surface opposite the third main surface. [Interlayer film] A 0.76 mm thick polyvinyl butyral was used as the interlayer film. [Laminated glass] The first glass, the interlayer film, and the second glass were laminated in this order, with the second main surface of the first glass facing the third main surface of the second glass, and pressure bonding was performed using an autoclave (1 MPa, 130°C, 3 hours) to produce the laminated glass of Example 1. The first glass was the outer sheet, and the second glass was the inner sheet.

[0137] (Examples 2 to 13) Laminated glasses of Examples 2 to 13 were produced in the same manner as in Example 1, except that the types and thicknesses of the first glass and the second glass were changed as shown in Tables 1 and 2.

[0138] The method for determining the values ​​shown in Tables 1 and 2 is described below.

[0139] (1) Glass Transition Temperature Tg The glass transition temperature Tg was measured using a differential thermal dilatometer (TMA) in accordance with JIS R3103-3:2001.

[0140] (2) Average Coefficient of Linear Expansion from 50° C. to 350° C. (CTE_50-350° C.) The average coefficient of linear expansion from 50° C. to 350° C. was measured using a differential thermal dilatometer (TMA) in accordance with JIS R3102:1995.

[0141] (3) Density r The density r was measured by Archimedes' method using a glass block of about 20 g containing no bubbles cut out from a glass plate.

[0142] (4) Young's modulus E, modulus of rigidity G, and Poisson's ratio v Young's modulus E, modulus of rigidity G, and Poisson's ratio v were measured at 25°C by an ultrasonic pulse method (Olympus, DL35) based on JIS R1602:1995 "Testing method for elastic modulus of fine ceramics."

[0143] (5) E / r E / r is expressed as an integer by rounding off the value obtained by dividing Young's modulus E by density r, using Young's modulus E and density r measured by the above method.

[0144] (6) Fracture toughness value (K ＩＣ ) Based on JIS R1607:2015 "Fracture toughness test method for fine ceramics", it was measured using a pre-crack introduction fracture test method (SEPB method: Single-Edge-Precracked-Beam method).

[0145] (7) Average chipping size The average chipping size on the edge of the first glass was determined by using a #230 electroplated grindstone at a grindstone rotation speed of 10,000 rpm and a feed rate of 200 mm / min to process the edge of the laminated glass of each example into a C-chamfered shape (C0.1, angle 45°). The size of the chipping occurring at the boundary between the first or second main surface and the edge was measured with a digital microscope, and the average value was calculated. The average chipping size on the edge of the second glass was determined by using a #230 electroplated grindstone at a grindstone rotation speed of 10,000 rpm and a feed rate of 200 mm / min to process the edge of the laminated glass of each example into a C-chamfered shape (C0.1, angle 45°). The size of the chipping occurring at the boundary between the third or fourth main surface and the edge was measured with a digital microscope, and the average value was calculated.

[0146] (8) Measurement of Absorbance Two types of glass samples with different thicknesses, a 2.0 mm glass sample and a 0.2 mm glass sample, were prepared according to the composition shown in Table 1. For each glass sample, the average absorbance of the glass in wavelength band A of 2.55 to 2.65 μm, wavelength band B of 2.7 to 3.0 μm, and wavelength band C of 3.4 to 3.9 μm was calculated from the internal transmittance of the glass measured using an FT-IR (Fourier transform infrared spectrophotometer). The average absorbance was calculated by averaging the values ​​measured every 1 nm in the specified wavelength region.

[0147] (9) Parameter X, Parameter Y Using the average absorbances of the first glass and the second glass in wavelength band A of 2.55 to 2.65 μm, wavelength band B of 2.7 to 3.0 μm, and wavelength band C of 3.4 to 3.9 μm measured in (8) above, parameter X was determined from the following formula (1), and parameter Y was determined from the following formula (4).

[0148]

[0149] (In formula (1), X １ is expressed by the following formula (2), and X ２ is expressed by the following formula (3):

[0150]

[0151] (In formulas (2) and (3), t１ is the thickness of the first glass (mm), and t ２ is the thickness of the second glass (mm), and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A, and P ｂ is the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A １，ｂ is the average absorbance of the first glass per mm in the wavelength band B, and A ２，ｂ is the average absorbance of the second glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A １，ｃ is the average absorbance of the first glass per mm in the wavelength band C, and A ２，ｃ is the average absorbance of the second glass per mm in the wavelength band C.

[0152]

[0153] (In formula (4), t １ , t ２ , P ａ , A １，ａ and A ２，ａ is the same as above.)

[0154] (10) Evaluation of Stone Chip Breaking Resistance Stone chipping resistance was evaluated by the following method. A 1.0 g ultra-steel indenter with a tip angle of 120 degrees and a tip curvature radius of 0.2 mm was collided perpendicularly with the surface of the first glass (outer panel) side of the laminated glass at a speed of 40 km / h, and the resistance was judged by the size of cracks that occurred starting from the second main surface of the first glass. Note that evaluation A is acceptable, and evaluation B is unacceptable. [Evaluation Criteria] A: The size of the crack that occurred was less than 8 mm. B: The size of the crack that occurred was 8 mm or more.

[0155] (11) Evaluation of distortion of laminated glass According to the standard of visual inspection by see-through at the time of product shipment, distortion defects that are visible to the driver in light of a limit sample of product defects were judged as distortion defects, and were evaluated based on the following criteria. Note that evaluation A is pass, and evaluation B is fail. [Evaluation criteria] A: Distortion defects cannot be judged by visual inspection. B: Distortion defects are judged by visual inspection.

[0156] The results are shown in Tables 1 and 2.

[0157]

[0158]

[0159] In the laminated glasses of Examples 1 to 11, the thickness of the first glass was 1 mm or more greater than the thickness of the second glass, and the parameter X was 0 or greater. The laminated glasses of Examples 1 to 11 were free of distortion defects and had both bending properties and strength properties. Among them, Examples 1 to 10 also had excellent resistance to stone chipping. On the other hand, the laminated glasses of Examples 12 and 13 were unable to achieve both bending properties and strength properties.

[0160] 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 thereto without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2024-155112) filed on September 9, 2024, the contents of which are incorporated herein by reference.

[0161] REFERENCE SIGNS LIST 10 Laminated glass 11 First glass 12 Second glass 13 Interlayer 20 Indenter 100 Automobile 110 Opening 120 Housing 150 Rearview mirror 201 Millimeter wave radar 202 Stereo camera 300 Radio wave S1 First principal surface S2 Second principal surface S3 Third principal surface S4 Fourth principal surface

Claims

1. A laminated glass in which a first glass sheet and a second glass sheet are laminated with an interlayer film, wherein the thickness of the first glass sheet is at least 1 mm thicker than the thickness of the second glass sheet, and the parameter X shown in the following formula (1) is 0 or greater. (In formula (1), X １ is expressed by the following formula (2), and X ２ is expressed by the following formula (3): (In formulas (2) and (3), t １ is the thickness (mm) of the first glass, and t ２ is the thickness (mm) of the second glass, and P ａ is the average radiance of the wavelength band A of 2.55 to 2.65 μm at 900 K according to Planck's radiation law, and is 0.2139 (J / s m ２ sr m), and A １，ａ is the average absorbance of the first glass per mm in the wavelength band A, and A ２，ａ is the average absorbance of the second glass per mm in the wavelength band A, and P ｂ is the average radiance of the wavelength band B of 2.7 to 3.0 μm at 900 K according to Planck's radiation law, and is 0.2315 (J / s m ２ sr m), and A １，ｂ is the average absorbance of the first glass per mm in the wavelength band B, and A ２，ｂ is the average absorbance of the second glass per mm in the wavelength band B, and P ｃ is the average radiance of the wavelength band C of 3.4 to 3.9 μm at 900 K according to Planck's radiation law, and is 0.2321 (J / s m ２ sr m), and A １，ｃ is the average absorbance of the first glass per mm in the wavelength band C, and A ２，ｃ is the average absorbance of the second glass per mm in the wavelength band C.

2. The laminated glass according to claim 1, wherein the parameter Y shown in the following formula (4) is 0 or greater. (In formula (4), t １ , t ２ , P ａ , A １，ａ and A ２，ａ is the same as above.) 3. X in the formula (1) １ The laminated glass according to claim 1 or 2, wherein the σ is 0.005 to 1.

3.

4. X in the formula (1) ２ The laminated glass according to claim 3, wherein the σ is 0.005 to 0.

35.

5. X in the formula (1) ２ The laminated glass according to claim 1 or 2, wherein the σ is 0.01 to 0.

35.

6. The laminated glass according to claim 1 or 2, wherein, when the edge of the laminated glass is processed into a C-chamfered 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, the average size of chipping generated at the boundary between the edge of the first glass and one main surface of the first glass or the other main surface opposite to the one main surface is 40 μm or less.

7. The laminated glass according to claim 1 or 2, wherein, when the edge of the laminated glass is processed into a C-chamfered 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, the average size of chipping generated at the boundary between the edge of the second glass and one main surface of the second glass or the other main surface opposite to the one main surface is 35 μm or less.

8. The laminated glass according to claim 1 or 2, wherein the thickness of the first glass sheet is 2.3 to 5.0 mm, and the thickness of the second glass sheet is 0.3 to 2.5 mm.

9. The fracture toughness of the first glass is 0.70 MPa m １／２ The laminated glass according to claim 1 or 2, wherein 10. The laminated glass according to claim 1 or 2, wherein the Young's modulus of the first glass is 60 GPa or more.

11. The density of the first glass and the second glass is 2.1 to 2.8 g / cm ３ The laminated glass according to claim 1 or 2, 12. The laminated glass according to claim 1 or 2, wherein the Poisson's ratio of the first glass and the second glass is 0.18 to 0.

27.

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

14. At least one of the first glass and the second glass has, in mass % on an oxide basis, 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 3. The laminated glass of claim 1 or 2, comprising:

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