Laminated glass for vehicles

Abstract

The present invention relates to a laminated glass for a vehicle, the laminated glass comprising: a first glass sheet having a convex first main surface and a concave second main surface; an intermediate film; and a second glass sheet having a convex third main surface and a concave fourth main surface. The first glass sheet has a sheet thickness of 3.1-5.0 mm and comprises a float glass having a surface compressive stress value of 20 MPa or greater when subjected to a physical reinforcement treatment. The second glass sheet has a sheet thickness of 0.4-1.3 mm and comprises a chemically reinforced float glass.

Description

Laminated glass for vehicles

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

[0002] BACKGROUND ART Laminated glass, which is formed by laminating a pair of glass sheets with an interlayer film interposed therebetween, is widely used as a glass member for a vehicle or the like.

[0003] When laminated glass for vehicles is used as, for example, automobile door glass, it is required to have high rigidity while also being lightweight. Therefore, a thin glass plate is used as one of the glass plates constituting the laminated glass and is subjected to a chemical strengthening treatment, thereby achieving weight reduction and ensuring rigidity.

[0004] As examples of such laminated glass, Patent Documents 1 and 2 disclose laminated glass for automobiles that employ a thin, chemically strengthened glass as the second glass sheet disposed on the interior side. These laminated glass for automobiles are manufactured by a technique called hot bending, in which the first glass sheet and the second glass sheet are heated to near the softening point of the glass in a stacked state and bent. More specifically, gravity bending and press forming methods are disclosed. In this way, the first glass sheet and the second glass sheet are bent simultaneously.

[0005] International Publication No. WO 2018 / 131280 International Publication No. WO 2018 / 131281

[0006] However, when a first glass sheet and a second glass sheet having different thicknesses are simultaneously bent by a hot bend, the difference in thickness causes a difference in the ease of bending of the glass sheets. The greater the difference in thickness between the glass sheets, the greater the difference in the ease of bending of the glass sheets. As a result, it has been found that during the bending process, a portion of the main surface of one glass sheet may come into contact with a portion of the main surface of the other glass sheet, causing distortion.

[0007] In addition to the above, it has been found that if two glass sheets are simultaneously bent and cooled using a hot bend and then subjected to a physical tempering treatment, the cooling rate of the opposing main surfaces of the two glass sheets becomes slower than that of the other main surface, and tempering by the physical tempering treatment is not effectively achieved.

[0008] Therefore, an object of the present invention is to provide a laminated glass for vehicles which has two glass plates with a specific difference in thickness, has excellent strength, and is prevented from generating distortion.

[0009] The present inventors have found that the above-mentioned problems can be solved by successively subjecting a thick first glass sheet disposed on the exterior side of the vehicle to bending forming by hot bending and physical strengthening treatment, and separately subjecting a thin second glass sheet disposed on the interior side of the vehicle to chemical strengthening treatment and bending forming called cold bending, thereby completing the present invention.

[0010] That is, one aspect of the present invention relates to the following: [1] A laminated glass for a vehicle, comprising a first glass plate, a second glass plate, and an interlayer film interposed between the first glass plate and the second glass plate, wherein the first glass plate has a first main surface and a second main surface opposing each other, the second main surface being located on the interlayer film side, the second glass plate has a third main surface and a fourth main surface opposing each other, the third main surface being located on the interlayer film side, the first glass plate is curved so that the first main surface side is convex and the second main surface side is concave, the first glass plate is made of float glass that has been physically strengthened, the thickness of the first glass plate is 3.1 to 5.0 mm, the first main surface and the second main surface of the first glass plate each have a surface compressive stress value of 20 MPa or more, the second glass plate is curved so that the third main surface side is convex and the fourth main surface side is concave, and the second glass plate is made of float glass that has been chemically strengthened. The laminated glass for vehicles, wherein the second glass sheet has a thickness of 0.4 to 1.3 mm. [2] The laminated glass for vehicles according to [1] above, wherein the surface compressive stress values ​​of the third main surface and the fourth main surface of the second glass sheet are each 400 to 900 MPa. [3] The laminated glass for vehicles according to [1] or [2] above, wherein the compressive stress layer depths of the third main surface and the fourth main surface of the second glass sheet are each 40 μm or less. [4] The laminated glass for vehicles according to any one of [1] to [3] above, wherein the second glass sheet has a tin content in the third main surface that is higher than the tin content in the fourth main surface. [5] The laminated glass for vehicles according to any one of [1] to [4] above, wherein the second glass sheet has a tin content in the fourth main surface that is higher than the tin content in the third main surface. [6] The matrix composition of the second glass sheet, expressed in mass percentage on an oxide basis, is: SiO ２ :60~80%, Al ２ O ３ : 1-8%, Na ２ O: 5-20%, K ２[7] The laminated glass for vehicles according to any one of [1] to [5], which satisfies the following compositional formulas: O: 0 to 5%, MgO: 4 to 12%, and CaO: 0 to 5%. [7] The laminated glass for vehicles according to [6], wherein the second glass sheet has a surface compressive stress value of 500 to 700 MPa on the third principal surface and the fourth principal surface, and a compressive stress layer depth of 40 μm or less on the third principal surface and the fourth principal surface of the second glass sheet. [8] The matrix composition of the second glass sheet, expressed in mole percentage on an oxide basis, is: SiO ２ :62~68%, Al ２ O ３ : 6-12%, Na ２ O: 9-17%, K ２ O: 0 to 7%, MgO: 7 to 13%, and ZrO ２ : Meets 0 to 0.8%, Na ２ O and K ２ The total content of O is ２ O ３ [9] The laminated glass for vehicles according to any one of [1] to [5], wherein the difference between the content of SiO and the content of SiO in the second glass sheet is less than 10%. [9] The laminated glass for vehicles according to [8], wherein the surface compressive stress values ​​of the third principal surface and the fourth principal surface of the second glass sheet are each 500 to 900 MPa, and the compressive stress layer depths of the third principal surface and the fourth principal surface of the second glass sheet are each 28 μm or more.

[10] The matrix composition of the second glass sheet, expressed in mass percentage on an oxide basis, is: SiO ２ :60~80%, Al ２ O ３ : 1-8%, Na ２ O: 5-20%, K ２

[11] The laminated glass for vehicles according to any one of [1] to [5], wherein the second glass sheet has a surface compressive stress value of 500 to 900 MPa on the third principal surface and a compressive stress layer depth of 20 μm or less on the fourth principal surface.

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

[11] , wherein the first glass sheet is bent by hot bending so that the first principal surface side is curved convexly and the second principal surface side is curved concavely, and the second glass sheet is bent by cold bending so that the third principal surface side is curved convexly and the fourth principal surface side is curved concavely.

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

[12] , wherein the difference in plate thickness between the first glass plate and the second glass plate is 2.0 mm or more.

[14] The laminated glass for a vehicle according to any one of [1] to

[13] , which is used as a door glass for an automobile.

[15] The laminated glass for a vehicle according to any one of [1] to

[14] , wherein the first glass plate is disposed on the vehicle exterior side and the second glass plate is disposed on the vehicle interior side.

[0011] According to the present invention, it is possible to provide a laminated glass for vehicles which has two glass plates with a specific difference in thickness, has excellent strength, and is prevented from generating distortion.

[0012] Fig. 1 is a schematic cross-sectional view of a laminated glass for vehicles according to one embodiment of the present invention. Fig. 2 is a graph showing the displacement and generated stress of Examples 2-1 to 2-9. Fig. 3 is a graph showing the rigidity of Examples 2-1 to 2-9.

[0013] Hereinafter, embodiments of the present invention will be described in detail. In this specification, with respect to the drawings, components and parts that perform the same function may be described by using the same reference numerals, and duplicated descriptions may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of an actual product.

[0014] In this specification, the term "base composition of glass" refers to the composition of a region not affected by ion exchange during chemical strengthening, i.e., the composition in a region deeper than the compressive stress layer depth of chemically strengthened glass, except in cases where extreme ion exchange has been performed. In this specification, the term "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. In this specification, "mass %" and "wt %" are synonymous.

[0015] <<Laminated Glass for Vehicles>> As shown in FIG. 1 , a laminated glass for vehicles 10 according to this embodiment (hereinafter sometimes simply referred to as "laminated glass") includes a first glass plate 11, a second glass plate 12, and an interlayer film 13 interposed between the first glass plate 11 and the second glass plate 12. The first glass plate 11 is a physically tempered float glass having a pair of opposing first and second main surfaces 11a and 11b, and a thickness of 3.1 to 5.0 mm. The second main surface 11b is located on the side of the interlayer film 13. The first glass plate 11 is curved so that the first main surface 11a side is convex and the second main surface 11b side is concave. The first main surface 11a and the second main surface 11b each have a surface compressive stress value CS of 20 MPa or more. On the other hand, the second glass plate 12 is a chemically strengthened float glass having a pair of opposing third and fourth principal surfaces 12a and 12b, and has a thickness of 0.4 to 1.3 mm. The third principal surface 12a is located on the side of the interlayer film 13. The second glass plate 12 is curved so that the third principal surface 12a side is convex and the fourth principal surface 12b side is concave.

[0016] In the laminated glass 10 according to this embodiment, the first glass sheet 11 has a thickness of 3.1 mm or more, and the second glass sheet 12 has a thickness of 1.3 mm or less, with a difference in thickness of 1.8 mm or more between the two glass sheets. It has been found that when such a difference in thickness exists, for example, when the first glass sheet 11 and the second glass sheet 12 are stacked in this order on a lower forming ring mold and simultaneously bent using a hot bend, a portion of the second major surface 11b of the first glass sheet 11 and a portion of the third major surface 12a of the second glass sheet 12 may come into contact, resulting in point-like distortion. Specifically, the thinner second glass sheet 12 is more likely to deform and sag downward than the thicker first glass sheet 11, resulting in increased contact pressure with the release agent disposed between the first glass sheet 11 and the second glass sheet 12. The release agent may then be transferred to a portion of the third major surface 12a of the second glass sheet 12, remaining as point-like distortion on the second glass sheet 12 even after bending, resulting in a poor appearance.

[0017] Furthermore, when two glass sheets are bent and continuously physically tempered using the heating of a hot bend, the first main surface 11 a of the first glass sheet 11 can be cooled at a desired cooling rate. On the other hand, the second main surface 11 b of the first glass sheet 11 faces the third main surface 12 a of the second glass sheet 12, and therefore can only be cooled at a rate slower than the desired cooling rate. As a result, the desired strength cannot be obtained, and a surface compressive stress value of 20 MPa or more cannot be achieved.

[0018] In contrast, if the first glass plate 11 is bent alone using a hot bend while undergoing physical strengthening treatment, both the first main surface 11a and the second main surface 11b are cooled at the desired cooling rate, and high strength can be achieved, with both surface compressive stress values ​​being 20 MPa or more.

[0019] Furthermore, the second glass sheet 12 is thinned to reduce its weight. By setting the thickness to 1.3 mm or less, it can be easily cold bent to achieve the desired shape, and its rigidity can be increased without increasing the weight of the laminated glass 10. For example, a laminated glass 10 having a first glass sheet 11 thickness of 3.5 mm and a second glass sheet 12 thickness of 0.5 mm has higher rigidity than a laminated glass having a first glass sheet thickness of 2.0 mm and a second glass sheet thickness of 2.0 mm, despite the same total thickness and total weight of the laminated glass 10. Furthermore, due to its thinness, the second glass sheet 12 can be chemically strengthened rather than physically strengthened to achieve the desired strength. Furthermore, since no release agent is used, point-like distortion does not occur in the second glass sheet 12.

[0020] Whether the laminated glass 10 according to the present embodiment is formed by overlapping the first glass sheet 11 and the second glass sheet 12 and simultaneously bending them by hot bending, or by bending the first glass sheet 11 by hot bending and the second glass sheet 12 by cold bending, can be determined by separating and removing the first glass sheet 11 and the second glass sheet 12 from the laminated glass 10 and observing the difference in their curvatures. Specifically, if the radius of curvature of the first glass sheet 11 is smaller than the radius of curvature of the second glass sheet 12, it can be determined that the first glass sheet 11 was bent by hot bending and the second glass sheet 12 was bent by cold bending.

[0021] <First Glass Sheet> The first glass sheet 11 in this embodiment is a float glass having a sheet thickness of 3.1 to 5.0 mm, which is thicker than the second glass sheet 12. The pair of opposing main surfaces of the first glass sheet 11 are curved such that the first main surface 11a is convexly curved and the second main surface 11b is concavely curved, and the second main surface 11b is positioned on the interlayer film 13 side. Here, it is preferable that the first main surface 11a side faces the exterior of the vehicle.

[0022] The first glass sheet 11 has a thickness of 3.1 mm or more, which is a thickness that allows it to be subjected to a physical tempering treatment. Therefore, the first glass sheet 11 is a physically tempered float glass, and the first main surface 11 a and the second main surface 11 b each have a surface compressive stress value of 20 MPa or more.

[0023] By setting the surface compressive stress value of not only the first main surface 11a but also the second main surface 11b to 20 MPa or more, excellent strength as a laminated glass for a vehicle can be achieved. For example, when the laminated glass 10 according to this embodiment is used as an automobile door glass, a strong impact is applied to the exposed edge of the laminated glass 10 when opening and closing a sashless door without a window frame or with the door glass open. Even in such cases, if the surface compressive stress value of both main surfaces is 20 MPa or more, good strength that will not break the door glass can be achieved.

[0024] The surface compressive stress values ​​of the first main surface 11a and the second main surface 11b may each be 20 MPa or more, preferably 20 to 200 MPa. From the viewpoint of achieving good strength, the surface compressive stress values ​​are each 20 MPa or more, preferably 30 MPa or more, and more preferably 50 MPa or more. There are no particular upper limits, but the value that can be achieved by physical strengthening treatment may be, for example, 200 MPa or less or 150 MPa or less.

[0025] In this embodiment, the first glass plate 11 can be bent independently by hot bending and physically strengthened using the heat generated during the bend process. Therefore, although the surface compressive stress values ​​of the first and second main surfaces 11a and 11b do not need to be identical, the first and second main surfaces 11a and 11b can have the same or similar compressive stress profiles. Therefore, the difference in the surface compressive stress values ​​between the first and second main surfaces 11a and 11b is, for example, 20 MPa or less, or may be 15 MPa or less, or 10 MPa or less. Furthermore, the difference in the surface compressive stress values ​​may be zero.

[0026] In this embodiment, the thickness of the first glass plate 11 is 3.1 to 5.0 mm, preferably 3.1 to 4.0 mm. From the viewpoints of the rigidity, sound insulation, and durability against impacts such as flying stones of the laminated glass, the thickness is 3.1 mm or more, preferably 3.5 mm or more, and may be 4.0 mm or more. From the viewpoint of weight reduction, the thickness is 5.0 mm or less, preferably 4.0 mm or less, and may be 3.5 mm or less.

[0027] The thickness of the first glass plate 11 may be constant over the entire surface, or may vary from place to place as necessary, such as by gradually decreasing. When the thickness is not constant, the thickness of the thickest part is defined as the thickness of the first glass plate 11.

[0028] In this embodiment, the shape of the main surface of the first glass plate 11 may be a curved shape having a curvature over the entire surface or a portion thereof. The curved shape may be a single curved shape that is curved only in one direction, either the up-down direction or the left-right direction, or a complex curved shape that is curved in both the up-down direction and the left-right direction. When the first glass plate 11 has a complex curved shape, the radius of curvature in the up-down direction and the left-right direction may be the same or different.

[0029] The shape of the main surface of the first glass plate 11 is suitably selected to fit the window opening of the vehicle in which it will be installed. For example, from the viewpoint of vehicle use, the first glass plate 11 in this embodiment preferably has a curved surface shape in which the first main surface 11 a side is convex and the second main surface 11 b side is concave.

[0030] The radius of curvature R of the first glass plate 11 is preferably, for example, 500 to 100,000 mm, and when used as a door glass for an automobile, it is more preferably 1,000 to 10,000 mm.

[0031] In this embodiment, the first glass sheet 11 is a float glass, which is preferable from the viewpoint of mass production of uniform glass sheets.

[0032] Float glass is a glass sheet manufactured by the float process. The tin content of both main surfaces of float glass differs due to the manufacturing process. Specifically, the surface on which the glass ribbon that will become the glass sheet comes into contact with the tin bath during the manufacturing process, i.e., the bottom surface, has a higher tin content. On the other hand, the other surface, i.e., the top surface, does not come into contact with the tin bath, so the tin content is zero or at least less than the tin content of the bottom surface.

[0033] Either the first main surface 11 a or the second main surface 11 b of the first glass plate 11 may be the bottom surface. This is because a physical tempering treatment is used as the tempering treatment for the first glass plate 11 and the plate thickness is as large as 3.1 mm or more, so that the effect of a difference in the tin content is extremely small.

[0034] Physical tempering, also known as air-cooling tempering, is a method of forming a compressive stress layer by thermally tempering a glass sheet. A glass sheet subjected to such physical tempering treatment is sometimes called physically tempered glass or physically tempered glass sheet. Specifically, this method involves uniformly heating a glass sheet to a temperature near its softening point and then rapidly cooling it, thereby generating compressive stress on the surface of the glass sheet due to the temperature difference between the surface and the interior of the glass sheet.

[0035] Physical tempering generates compressive stress uniformly across the entire surface of the glass plate, resulting in the formation of a compressive stress layer of uniform depth across the entire main surface of the glass plate. Physical tempering is more suitable for strengthening thick glass plates than chemical tempering. Physical tempering is also a less expensive method than chemical tempering.

[0036] The composition of the first glass plate 11 in this embodiment is not particularly limited as long as it is physically strengthened float glass, and examples thereof include soda-lime glass, borosilicate glass, aluminosilicate glass, alkali-free glass, quartz glass, etc. From the viewpoints of formability and production costs, soda-lime glass is preferred.

[0037] Soda lime glass is made of SiO ２ , Na ２The specific composition is not particularly limited as long as it contains O and CaO. For example, the glass may have the following oxide-based mass percentage content: (Composition 1) SiO ２ :60-80%, Na ２ Glass containing O: more than 0% and CaO: 6 to 14%. (Composition 2) SiO ２ :65~75%, Al ２ O ３ : 0-5%, Na ２ O: 5-20%, K ２ O: 0 to 5%, MgO: 0 to 7%, CaO: 6 to 13%, and (Na ２ O+K ２ O): Glass that fills 5-20%.

[0038] In the above composition 1 or composition 2, Al ２ O ３ Also preferred is a glass having a content of less than 1%.

[0039] The annealing point of the first glass plate 11 in this embodiment is not particularly limited, but is typically about 550° C. In this specification, the annealing point is the temperature at which the viscosity of the glass reaches 10 １３ This refers to the temperature at which the viscosity becomes dPa·s, and can be adjusted by the glass composition, etc.

[0040] The softening point of the first glass plate 11 in this embodiment is not particularly limited, but is typically about 750° C. In this specification, the softening point is the temperature at which the viscosity of the glass reaches 10 ７．６５ This refers to the temperature at which the viscosity becomes dPa·s, and can be adjusted by the glass composition, etc.

[0041] <Second Glass Sheet> The second glass sheet 12 in this embodiment is a float glass and has a thickness of 0.4 to 1.3 mm, which is thinner than the first glass sheet 11. The pair of opposing main surfaces of the second glass sheet 12 are curved such that the third main surface 12a side is convex and the fourth main surface 12b side is concave, and the third main surface 12a is positioned on the interlayer film 13 side. Here, it is preferable that the fourth main surface 12b is positioned to face the vehicle interior side.

[0042] Since the second glass sheet 12 has a thickness of 1.3 mm or less, it is subjected to a chemical tempering process rather than a physical tempering process, which gives it sufficient strength as a glass sheet constituting a laminated glass for a vehicle. Therefore, the second glass sheet 12 is a chemically tempered float glass.

[0043] The surface compressive stress values ​​of the third main surface 12a and the fourth main surface 12b are preferably 400 to 900 MPa. From the viewpoint of achieving good strength, the surface compressive stress values ​​are preferably 400 MPa or more, more preferably 500 MPa or more, even more preferably 600 MPa or more, and may be 700 MPa or more. The upper limit is not particularly limited, but from the viewpoint of the balance between compressive stress and tensile stress, it is preferably 900 MPa or less, more preferably 800 MPa or less, and may be 700 MPa or less. The surface compressive stress value can be adjusted by the glass composition, the time for chemical strengthening treatment, the chemical strengthening treatment temperature, the type of molten salt, and the like.

[0044] The second glass plate 12 in this embodiment can be chemically strengthened by a conventionally known method. Therefore, although the surface compressive stress values ​​of the third and fourth main surfaces 12a and 12b do not need to be identical, the third and fourth main surfaces 12a and 12b can have the same or similar compressive stress profiles. Therefore, the difference in the surface compressive stress values ​​between the third and fourth main surfaces 12a and 12b is, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less. While the lower limit of the difference in the surface compressive stress values ​​is not particularly limited, the second glass plate 12 is float glass, and differences in the tin content between the two main surfaces result in differences in the way stress is applied. Therefore, differences in the surface compressive stress values ​​between the two main surfaces are likely to occur.

[0045] The compressive stress layer depth DOL (depth of layer) of the third main surface 12a and the fourth main surface 12b is not particularly limited, but is preferably 50 μm or less, and preferably 2 to 40 μm. From the viewpoint of obtaining sufficient strength, the compressive stress layer depth is preferably 2 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, particularly preferably 20 μm or more, and may be 28 μm or more, or may be 30 μm or more. Furthermore, from the viewpoint of shortening the chemical strengthening treatment time, the compressive stress layer depth is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 35 μm or less, and may be 30 μm or less, or may be 20 μm or less. The compressive stress layer depth can be adjusted by the glass composition, the time for chemical strengthening treatment, the chemical strengthening treatment temperature, the type of molten salt, etc.

[0046] In this embodiment, the third main surface 12a and the fourth main surface 12b of the second glass plate 12 each preferably have a surface compressive stress value of 400 to 900 MPa and a compressive stress layer depth of 50 μm or less. In another aspect, the surface compressive stress value is more preferably 500 to 700 MPa and a compressive stress layer depth of 40 μm or less. In another aspect, the surface compressive stress value is more preferably 500 to 900 MPa and a compressive stress layer depth of 28 μm or more. In another aspect, the surface compressive stress value is more preferably 500 to 900 MPa and a compressive stress layer depth of 20 μm or less.

[0047] In this embodiment, the thickness of the second glass sheet 12 is 0.4 to 1.3 mm, preferably 0.7 to 1.1 mm. From the viewpoint of ensuring the rigidity of the laminated glass, the thickness is 0.4 mm or more, preferably 0.5 mm or more, and more preferably 0.7 mm or more. From the viewpoint of weight reduction, the thickness is preferably 1.3 mm or less, more preferably 1.1 mm or less, and may be 0.7 mm or less.

[0048] The thickness of the second glass plate 12 may be constant over the entire surface, or may vary from place to place as necessary, such as gradually decreasing. When the thickness is not constant, the thickness of the thickest part is defined as the thickness of the second glass plate 12.

[0049] Furthermore, as described above, the thickness of the first glass sheet 11 is 3.1 to 5.0 mm, and therefore the difference in thickness between the first glass sheet 11 and the second glass sheet 12 is at least 1.8 mm. Due to this difference, when the first glass sheet 11 and the second glass sheet 12 are stacked and simultaneously bent by hot bending, as described above, distortion may occur due to contact between the first glass sheet 11 and the second glass sheet 12. In addition, the difference in thickness makes bending difficult.

[0050] Thus, the greater the difference in thickness between the first glass sheet 11 and the second glass sheet 12, the more likely the problems of the present invention will occur, and at the same time, the more likely the effects of the present invention will be achieved. From the viewpoint of suitably achieving the effects of the present invention, the difference in thickness between the first glass sheet 11 and the second glass sheet 12 is 1.8 mm or more, preferably 2.0 mm or more, and more preferably 2.4 mm or more. Furthermore, the upper limit of the difference in thickness is at most 4.6 mm, and from the viewpoint of controlling the shape of the first glass sheet 11 as laminated glass after bending and forming it, the difference is preferably 4.3 mm or less, and more preferably 3.3 mm or less. Examples of combinations of the thicknesses of the first glass sheet 11 and the second glass sheet 12 that result in a difference in thickness within the above range include a combination of 3.1 mm or more and 1.1 mm or less, and a combination of 3.5 mm or more and 1.1 mm or less.

[0051] In this embodiment, the shape of the main surface of the second glass plate 12 may be a curved shape having a curvature over the entire surface or a portion thereof. The curved shape may be a single curved shape that is curved only in one direction, either the up-down direction or the left-right direction, or a complex curved shape that is curved in both the up-down direction and the left-right direction. When the second glass plate 12 has a complex curved shape, the radius of curvature in the up-down direction and the left-right direction may be the same or different.

[0052] The shape of the main surface of the second glass plate 12 is appropriately selected to fit the window opening of the vehicle in which it will be installed. For example, from the viewpoint of vehicle applications, it is preferable that the second glass plate 12 in this embodiment has a curved shape in which the third main surface 12a side is convex and the fourth main surface 12b side is concave. That is, it is more preferable that the first glass plate 11 has a convex shape on the first main surface 11a side and a concave shape on the second main surface 11b side, and that the second glass plate 12 has a convex shape on the third main surface 12a side and a concave shape on the fourth main surface 12b side.

[0053] The radius of curvature R of the second glass plate 12 may be, for example, about 10,000 mm.

[0054] The difference in curvature between the first glass plate 11 and the second glass plate 12 is set to 0.001 mm from the viewpoint of facilitating lamination and pressure bonding of the two glass plates. －１ Preferably, 0.0007 mm or less －１ More preferably, 0.0004 mm or less －１ The following is even more preferred:

[0055] In this embodiment, the second glass sheet 12 is a float glass, which is preferable from the viewpoint of mass production of uniform glass sheets.

[0056] As mentioned above, float glass has different tin contents on its two main surfaces. When such glass is chemically strengthened, the top surface, which has a lower tin content, is more susceptible to stress due to ion exchange than the bottom surface, which has a higher tin content. As a result, the glass is more likely to warp, with the top surface being convex and the bottom surface being concave. The thinner the thickness of the second glass sheet 12, the more pronounced the warpage.

[0057] As described above, the second glass plate 12 in this embodiment preferably has a curved surface shape in which the third main surface 12a is convex and the fourth main surface 12b is concave. Here, the second glass plate 12 may be positioned so that the tin content in the third main surface 12a is greater than the tin content in the fourth main surface 12b. This means that the top surface with a lower tin content is positioned as the fourth main surface 12b. This improves the strength of the entire laminated glass 10.

[0058] On the other hand, the second glass 12 in this embodiment may be arranged so that the tin content in the third major surface 12 a is lower than the tin content in the fourth major surface 12 b. This means that the top surface with the lower tin content is arranged as the third major surface 12 a. This allows the top surface, which is convex, to be positioned on the third major surface 12 a side, which is curved convexly, thereby improving productivity when manufacturing the laminated glass 10.

[0059] The second glass plate 12 is a glass plate that has been chemically strengthened. A glass plate that has been chemically strengthened in this manner may be referred to as chemically strengthened glass or a chemically strengthened glass plate. Chemical strengthening is a process in which alkali metal ions with a small ionic radius on the glass surface are exchanged with alkali metal ions with a larger ionic radius by ion exchange at a temperature below the glass transition point, thereby forming a compressive stress layer on the glass surface. Specifically, this is a method in which Li ions on the glass surface are ion-exchanged with Na ions, or Na ions on the glass surface are ion-exchanged with K ions. In this embodiment, from the viewpoint of production costs, it is preferable that the second glass plate 12 be chemically strengthened glass in which Na ions on the glass surface are ion-exchanged with K ions.

[0060] Chemical strengthening treatment can be performed by known methods. One example is the ion exchange method. In the ion exchange method, a glass plate is immersed in a treatment solution, and ions with a small ionic radius contained in the glass are exchanged for ions with a large ionic radius, thereby generating compressive stress on the glass surface. An example of the treatment solution is a molten salt containing potassium nitrate as an inorganic salt. By immersing glass containing Na ions in the molten salt, the Na ions on the glass surface are exchanged for K ions in the molten salt.

[0061] The composition of the second glass plate 12 in this embodiment is not particularly limited as long as it is float glass containing an alkali metal for chemical strengthening treatment, but examples thereof include aluminosilicate glass, soda-lime glass, etc. From the viewpoint of improving strength, aluminosilicate glass is preferred. Furthermore, from the viewpoint of ease of forming a glass ribbon in the float process, soda-lime glass is preferred.

[0062] The base composition of the second glass plate 12 in this embodiment is expressed in terms of mass percentage based on oxides: SiO ２ :60~80%, Al ２ O ３ : 1-8%, Na ２ O: 5-20%, K ２ It is preferable that the following contents are satisfied: O: 0 to 5%, MgO: 4 to 12%, and CaO: 0 to 5%.

[0063] In addition to the above, B ２ O ３ : 0 to 4%, BaO: 0 to 5%, and Fe ２ O ３ It is more preferable that one or more of the following be further satisfied: 0.002 to 0.04%.

[0064] Each component will be described below.

[0065] SiO ２ is a component that contributes to improving Young's modulus, thereby making it easier to ensure the strength required for vehicle applications, etc. ２ The content of is preferably 60 to 80%. From the viewpoints of reducing the specific gravity of the glass, ensuring weather resistance and chemical durability, and suppressing an increase in the average linear expansion coefficient to suppress thermal cracking of the glass, the content is preferably 60% or more, more preferably 63% or more, even more preferably 65% ​​or more, and may be 68% or more, or may be 70% or more. Furthermore, from the viewpoints of ease of glass production and formability by suppressing an increase in viscosity during glass melting, the content is preferably 80% or less, more preferably 79% or less, and even more preferably 78% or less.

[0066] Al ２ O ３Al is a component that reduces non-bridging oxygen in the glass by adopting a tetrahedral structure in which an alkali metal is coordinated, thereby improving weather resistance, discoloration resistance, and chemical durability. Furthermore, Al does not increase the average linear expansion coefficient too much, thereby suppressing thermal cracking of the glass and facilitating chemical strengthening treatment using ion exchange. ２ O ３ The content of Al is preferably 1 to 8%. ２ O ３ From the viewpoint of preferably obtaining the above-mentioned effect by Al ２ O ３ The content is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, may be 5% or more, or may be 6.5% or more. From the viewpoint of ease of glass production and formability by suppressing an increase in viscosity during glass melting, the content is preferably 8% or less, more preferably 6% or less, and even more preferably 5% or less.

[0067] B ２ O ３ is a component that controls the optical properties of the glass, reduces the specific gravity of the glass, and also contributes to improving the strength and meltability of the glass. ２ O ３ The content of is preferably 0 to 4%. ２ O ３ may not be included, but B ２ O ３ From the viewpoint of preferably obtaining the above-mentioned effect by B ２ O ３ In order to prevent deterioration in glass quality due to volatilization of alkali metal elements during glass melting and forming, and from the viewpoint of acid resistance and alkali resistance, the content is preferably 4% or less, more preferably 2% or less, and even more preferably 1% or less.

[0068] Na ２ O is a component that improves the meltability of glass. It also increases the Young's modulus, contributes to the linear expansion coefficient of glass, and improves the formability of glass by reducing its viscosity. Furthermore, it increases the strength of glass through chemical strengthening treatment by ion exchange with K ions. Na ２The content of O is preferably 5 to 20%. ２ From the viewpoint of suitably obtaining the above-mentioned effects of O, the content is preferably 5% or more, more preferably 8% or more, still more preferably 10% or more, may be 14% or more, or may be 16.5% or more. Moreover, from the viewpoint of suppressing thermal cracking of the glass and improving the tarnish resistance by reducing the linear expansion coefficient, the content is preferably 20% or less.

[0069] K ２ O is a component that improves the meltability of glass. It also increases the Young's modulus, contributes to the linear expansion coefficient of glass, and improves the moldability of glass by reducing its viscosity. ２ The content of O is preferably 0 to 5%. ２ It may not contain O, but K ２ From the viewpoint of preferably obtaining the above-mentioned effect of O, K ２ When O is contained, the content is preferably more than 0%, more preferably 1% or more, may be 1.5% or more, or may be 2% or more. From the viewpoint of suppressing an increase in the linear expansion coefficient and specific gravity, the content is preferably 5% or less.

[0070] MgO is a component that promotes the melting of glass raw materials and improves weather resistance, discoloration resistance, and Young's modulus. The MgO content is preferably 4 to 12%. Here, from the viewpoint of meltability and Young's modulus, the content is preferably 4% or more, may be 7% or more, or may be 10% or more. Furthermore, from the viewpoint of suppressing devitrification of the glass and an increase in viscosity during melting, the content is preferably 12% or less, more preferably 10% or less, and even more preferably 8% or less.

[0071] CaO is a component that improves the meltability of glass raw materials. The CaO content is preferably 0 to 5%. Here, from the viewpoints of meltability and formability, the content, when CaO is contained, is preferably 0.5% or more, more preferably 1% or more, and even more preferably 2% or more. Furthermore, from the viewpoints of avoiding an increase in the density of the glass, suppressing low brittleness, and maintaining strength, the content is preferably 5% or less, more preferably 4.5% or less, and even more preferably 4% or less.

[0072] BaO is a component that improves the meltability of glass raw materials. On the other hand, it may increase the specific gravity of the glass or reduce the brittleness of the glass, resulting in a decrease in the strength of the glass. Therefore, BaO may not be contained, and its content is preferably, for example, 0 to 5%. Here, BaO may not be contained, but if it is contained, from the viewpoints of meltability and formability, the content is preferably more than 0%, more preferably 0.1% or more. Furthermore, from the viewpoint of maintaining strength, the content is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less.

[0073] Fe ２ O ３ may be contained to impart heat-shielding properties. ２ O ３ The content of Fe in this specification is preferably 0.002 to 0.04%. ２ O ３ The content of FeO, which is an oxide of divalent iron, and Fe, which is an oxide of trivalent iron ２ O ３ Here, Fe means the total amount of iron, including ２ O ３ When Fe is contained, from the viewpoint of heat-shielding properties, the content is preferably 0.002% or more, more preferably 0.005% or more, and even more preferably 0.01% or more. Furthermore, from the viewpoint of meltability during glass production and high transmittance in the visible range, if the content is 0.002% or more, the glass can be suitably used in applications where heat-shielding properties are required. ２ O ３ The content of is preferably 0.04% or less, more preferably 0.03% or less, and further preferably 0.02% or less.

[0074] The second glass plate 12 in this embodiment may contain other components in addition to those described above. When other components are contained, the total content thereof is preferably 1% or less.

[0075] Other components include, for example, Li ２ O, SrO, ZrO ２ , Y ２ O ３ , TiO ２ , CeO ２ , Nd ２ O ５ , GaO２ , 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.

[0076] The annealing point of the second glass plate 12 in this embodiment is not particularly limited, but is typically about 578°C.

[0077] The softening point of the second glass plate 12 in this embodiment is not particularly limited, but is typically about 766°C.

[0078] Another base composition of the second glass plate 12 in this embodiment is, in terms of mole percentage on an oxide basis, SiO ２ :62~68%, Al ２ O ３ : 6-12%, Na ２ O: 9-17%, K ２ O: 0 to 7%, MgO: 7 to 13%, and ZrO ２ : Meets 0 to 0.8%, Na ２ O and K ２ The total content of O is ２ O ３ It is preferable that the difference between the contents of is less than 10%.

[0079] The second glass plate satisfying the above-described matrix composition may have, for example, a surface compressive stress value of 500 to 900 MPa on each of the third and fourth main surfaces, and a compressive stress layer depth of 28 μm or more on each of the third and fourth main surfaces of the second glass plate.

[0080] Another base composition of the second glass plate 12 in this embodiment is, in terms of mole percentage on an oxide basis, SiO２ :62~66%, Al ２ O ３ : 6-12%, Na ２ O: 9-17%, K ２ O: 0 to 7%, and MgO: 7 to 13%, and ZrO ２ : Meets 0 to 0.8%, Na ２ O and K ２ The total content of O is ２ O ３ It is preferable that the difference between the contents of is less than 10%.

[0081] Another base composition of the second glass plate 12 in this embodiment is, in terms of mole percentage on an oxide basis, SiO ２ :64-68%, Al ２ O ３ : 6-11%, Na ２ O: 12-17%, K ２ O: 0 to 6%, MgO: 7 to 12%, and ZrO ２ : Meets 0 to 0.8%, Na ２ O and K ２ The total content of O is ２ O ３ It is preferable that the difference between the contents of is less than 10%.

[0082] Another base composition of the second glass plate in this embodiment is, in terms of mass percentage based on oxides, SiO ２ :60~80%, Al ２ O ３ : 1-8%, Na ２ O: 5-20%, K ２ It is preferable that the following contents are satisfied: O: 0 to 5%, MgO: 0 to 7%, and CaO: 3 to 10%.

[0083] The second glass plate satisfying the above-described matrix composition may have, for example, a third main surface and a fourth main surface each having a surface compressive stress value of 500 to 900 MPa, and a compressive stress layer depth of the third main surface and the fourth main surface of the second glass plate each being 20 μm or less.

[0084] Another base composition of the second glass plate in this embodiment is, in terms of mass percentage based on oxides, SiO２ :60~80%, Al ２ O ３ : 3-8%, Na ２ O: 5-20%, K ２ It is more preferable that the following contents are satisfied: O: 0 to 5%, MgO: 0 to 7%, and CaO: 3 to 10%.

[0085] <Interlayer Film> In this embodiment, the interlayer film 13 is interposed between the first glass plate 11 and the second glass plate 12. The first glass plate 11 and the second glass plate 12 are firmly bonded together via the interlayer film 13. Furthermore, even if an object collides with the laminated glass 10, the interlayer film 13 can absorb the impact.

[0086] The interlayer film 13 in this embodiment may be any interlayer film that has been conventionally used in laminated glass for vehicles.

[0087] Examples of organic resins constituting the intermediate film 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 poly Examples of the suitable polyvinyl vinyl resin include polyvinyl formal (PVF), polyvinyl alcohol (PVAL), vinyl acetate resin (PVAc), ionomer (IO), polymethylpentene (PMP), 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 more preferred from the viewpoint of providing sound insulation.

[0088] The thickness of the interlayer film 13 is preferably 0.5 to 3 mm. From the viewpoints of impact absorption and sound insulation, the thickness is preferably 0.5 mm or more. From the viewpoint of suppressing a decrease in visible light transmittance, the thickness is preferably 3 mm or less, more preferably 2.8 mm or less, and even more preferably 2.6 mm or less. The thickness of the interlayer film 13 may be uniform over the entire surface, or may vary from place to place as necessary.

[0089] In this embodiment, it is preferable that the difference between the linear expansion coefficient of the interlayer film 13 and the linear expansion coefficients of the first glass sheet 11 and the second glass sheet 12 is small. This is to prevent poor appearance due to cracking or warping of the glass sheets when producing the laminated glass 10.

[0090] In this embodiment, the interlayer film 13 may be a film formed from the above resin, or may be an adhesive layer containing an adhesive. The adhesive is not particularly limited, but examples thereof include acrylic adhesives and silicone adhesives. When the adhesive layer is used as the interlayer film 13, a heating step is not required in the process of joining the first glass plate 11 and the second glass plate 12. Therefore, the cracking and warping described above can be suppressed.

[0091] <Other Layers> The laminated glass 10 according to this embodiment may include any other layer in addition to the first glass plate 11, the second glass plate 12, and the interlayer film 13, as long as the effects of the present invention are not impaired. Examples of other layers include a coating layer that imparts water-repellent properties, hydrophilic properties, anti-fogging properties, etc., an infrared reflective film, a black ceramic layer, etc.

[0092] The arrangement of the other layer is not particularly limited, and may be, for example, provided on at least one surface of the laminated glass 10, i.e., on the first major surface 11a of the first glass plate 11 or the fourth major surface 12b of the second glass plate 12. Alternatively, the other layer may be provided on the second major surface 11b of the first glass plate 11 or the third major surface 12a of the second glass plate 12.

[0093] The laminated glass 10 may further include a black ceramic layer or the like for the purpose of concealing the attachment portion to the frame or the wiring conductors, etc. In this case, the black ceramic layer may be provided in a strip shape along part or all of the peripheral edge of the laminated glass 10.

[0094] <Shape> In the laminated glass 10 according to this embodiment, there are no particular limitations on the shape of the first glass sheet 11 or the second glass sheet 12. For example, when the laminated glass 10 is used as an automobile door glass, the area of ​​the main surface of at least one of the first glass sheet 11 and the second glass sheet 12 is 250,000 to 4,000,000 mm ２ Here, the above area is set to 250,000 mm depending on the vehicle type. ２ or more, 450,000 mm ２ It may be more than 900,000 mm ２ In addition, from the viewpoint of ease of handling, uniformity of temperature distribution during heating, dimensional accuracy after bending, bending formability, etc., the above area is 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:

[0095] The overall thickness of the laminated glass 10 of this embodiment is not particularly limited, but is preferably, for example, 4.5 to 10 mm. From the viewpoint of achieving good strength, the thickness is preferably 4.5 mm or more, more preferably 4.8 mm or more, even more preferably 5.0 mm or more, even more preferably 5.1 mm or more, particularly preferably 5.2 mm or more, and most preferably 5.3 mm or more. From the viewpoint of weight reduction, the thickness is preferably 10 mm or less, more preferably 9.0 mm or less, even more preferably 8.0 mm or less, even more preferably 7.0 mm or less, particularly preferably 6.5 mm or less, and most preferably 6.0 mm or less.

[0096] The thickness of the laminated glass 10 of this embodiment may be constant over the entire surface, or may vary from place to place as needed, such as by gradually tapering. If the thickness is not constant, the thickness at the thickest point is taken as the thickness of the entire laminated glass 10.

[0097] <Applications> The laminated glass 10 according to the present embodiment is used in vehicles, and is preferably used in automobiles, and more preferably used as vehicle door glass. When the vehicle door glass is a sashless glass that requires greater rigidity, the laminated glass 10 according to the present embodiment is particularly suitable.

[0098] <<Method for Manufacturing Laminated Glass>> The method for manufacturing the laminated glass 10 according to this embodiment is not particularly limited as long as it can produce the laminated glass described in the above <<Laminated Glass for Vehicles>>. The manufacturing method according to this embodiment includes, for example, the following steps: preparing float glass A having a thickness of 3.1 to 5.0 mm, bending the float glass A by hot bending, physically strengthening the bent float glass A, preparing float glass B having a thickness of 0.4 to 1.3 mm, chemically strengthening the float glass B, laminating the chemically strengthened float glass B on the physically strengthened and bent float glass A via an interlayer film, and bending the laminated glass by cold bending, and bonding the chemically strengthened and bent float glass B to the physically strengthened and bent float glass A via an interlayer film.

[0099] Of the above steps, the step of hot bending the float glass A and the step of physically strengthening the bent float glass A are preferably carried out continuously from the viewpoint of productivity.

[0100] The float glass A having a thickness of 3.1 to 5.0 mm may be commercially available, manufactured, or processed. When manufacturing or processing the float glass, a conventionally known method can be used.

[0101] The float glass A is bent by a hot bend. The temperature at this time is, for example, when the viscosity η of the glass sheet is 10 ７．６５ It can be determined based on the softening point, which is the temperature at which the viscosity reaches dPa·s.

[0102] The physical tempering treatment of float glass A can be carried out by a conventionally known method. Specifically, a uniformly heated glass sheet is rapidly cooled from a temperature near the softening point, and compressive stress is generated on the glass surface due to the temperature difference between the glass surface and the glass interior. The heating temperature and the rapid cooling rate may be appropriately set according to the desired physical properties. However, by using the heating in the bending process and rapid cooling after bending, bending and physical tempering can be carried out continuously.

[0103] The float glass B having a thickness of 0.4 to 1.3 mm may be commercially available, manufactured, or processed. When manufacturing or processing the float glass B, a conventionally known method can be used.

[0104] A conventionally known method can be used for chemical strengthening treatment of the float glass B. Specifically, when Na ions on the surface of the float glass B are ion-exchanged with K ions, the float glass B is immersed in a molten salt containing a potassium salt. Examples of the potassium salt contained in the molten salt include potassium nitrate, potassium sulfate, and potassium carbonate. Of these, potassium nitrate is preferred. The molten salt may contain one type of potassium salt or two or more types of potassium salts.

[0105] The conditions such as the concentration and temperature of the molten salt, and the time for immersing the glass may be appropriately determined according to the desired physical properties.

[0106] From the viewpoint of production costs, it is preferable to bend the float glass B by cold bending. Cold bending is a method of elastically deforming glass without heating it to a specific temperature.

[0107] The process of bonding, via an interlayer, float glass B that has been chemically strengthened and bent to float glass A that has been physically strengthened and bent, can be carried out, for example, by laminating float glass A, interlayer film, and float glass B in this order and then subjecting them to pressure bonding using an autoclave, etc. The pressure, temperature, time, and other conditions of the pressure bonding process can be appropriately set according to the desired properties.

[0108] Alternatively, a laminated glass may be obtained by laminating float glass A and float glass B, inserting an interlayer film therebetween, and subjecting them to pressure bonding.

[0109] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0110] <<Preparation of First Glass Plate: Glass Plate A (Glasses A1-A2)>> A 3.5 mm thick float glass having the glass composition (unit: mass %) shown in Table 1 was processed, and the resulting float glass plate was heated to 690°C, bent using a downward forming ring mold, and then rapidly cooled to room temperature to obtain physically tempered Glass A1. The resulting Glass A1 had a complex curved shape that was curved in two directions. Of the pair of opposing main surfaces of Glass A1, the convexly curved side was designated the first main surface, and the concavely curved side was designated the second main surface.

[0111] Glass A2 was produced in the same manner as Glass A1, except that the thickness of the float glass was 4.0 mm. The obtained Glass A2 had a complex curved shape that was curved in two directions.

[0112] <<Preparation of Second Glass Plate: Glass Plate B (Glass B1 to Glass B3)>> Float glasses having a thickness of 1.1 mm and having the glass compositions (units: mass %) shown in Table 1 were each processed, and each of the resulting float glass plates was subjected to a chemical strengthening treatment by immersing it in molten salt at 450° C. for 2 hours. The potassium salt contained in the molten salt was potassium nitrate, and its content was 95 mass %.

[0113]

[0114] Examples 1-1 to 1-6: Preparation of Laminated Glasses 1 to 6 Glasses A1 and A2, a 0.76 mm-thick PVB interlayer, and glasses B1 to B3 were laminated in this order. Glasses B1 to B3 were then cold-bent using a temporary fastening device, a preliminary pressure-bonding device, and an autoclave. Each of the resulting glasses B1 to B3 had a complex curved shape, with curvature in two directions. Of the pair of opposing main surfaces of each of glasses B1 to B3, the convexly curved side was designated the third main surface, and the concavely curved side was designated the fourth main surface. The second main surfaces of glasses A1 and A2 were in contact with the PVB interlayer, and the PVB interlayer was in contact with the third main surface of each of glasses B1 to B3. Then, a pressure-bonding process was performed in an autoclave at 1 MPa, 100°C, and for 30 minutes, yielding laminated glasses 1 to 6. That is, laminated glass 1 in Example 1-1 is composed of glass A1, a PVB interlayer, and glass B1, laminated glass 2 in Example 1-2 is composed of glass A1, a PVB interlayer, and glass B2, laminated glass 3 in Example 1-3 is composed of glass A1, a PVB interlayer, and glass B3, laminated glass 4 in Example 1-4 is composed of glass A2, a PVB interlayer, and glass B1, laminated glass 5 in Example 1-5 is composed of glass A2, a PVB interlayer, and glass B2, and laminated glass 6 in Example 1-6 is composed of glass A2, a PVB interlayer, and glass B3.

[0115] <Evaluation> <Surface compressive stress value, compressive stress layer depth> Before preparing the laminated glass, the surface compressive stress values ​​of both main surfaces of each of Glasses A1 to A2 and Glasses B1 to B3 were measured using a scattered light photoelastic stress meter (Orihara Seisakusho, SLP-2000) and a glass surface stress meter (Orihara Seisakusho, FSM). The compressive stress layer depth was also measured for both main surfaces of each of Glasses B1 to B3. The results are shown in Table 2. As described above, the convex surfaces of Glasses A1 to A2 are the first main surfaces, the concave surfaces are the second main surfaces, and the convex surfaces of Glasses B1 to B3 are the third main surfaces and the concave surfaces are the fourth main surfaces.

[0116] <Distortion> The presence or absence of distortion in the obtained laminated glasses 1 to 6 was visually evaluated using an inspection light source unit (arctruth 230VILS, manufactured by Ushio Inc.) As a result, it was confirmed that all the laminated glasses were free of distortion.

[0117]

[0118] Example 2-1 to Example 2-9: Study on the Difference in Thickness Between the First Glass Plate and the Second Glass Plate The thickness of the first glass plate was t1 (mm), the thickness of the second glass plate was t2 (mm), and the first and second glass plates were overlapped and a constant load was applied. The displacement, generated stress, and rigidity were examined by varying the thickness of the first glass plate (t1) and the thickness of the second glass plate (t2) as shown in Table 3. Specifically, a static study was conducted using the plate small deformation bending theory under the condition that the two glass plates were in the same deformation state and were not constrained to each other. Here, for a constant load, the displacement is inversely proportional to the cube of the plate thickness, and for the same displacement, the generated stress is proportional to the plate thickness. The standard for the displacement, generated stress, and rigidity was the case of a single plate with a plate thickness of 4 mm (Example 2-1). Furthermore, the composition of the first glass plate and the second glass plate in all examples was the same, and differences in the type of glass did not affect the displacement, generated stress, and rigidity. Furthermore, the presence or absence of physical strengthening treatment and chemical strengthening treatment does not affect rigidity.

[0119] In the above study, it is assumed that no interlayer film is present between the first glass sheet and the second glass sheet, and further that the first glass sheet and the second glass sheet are flat. Here, if the constraint between the first glass sheet and the second glass sheet by the interlayer film cannot be ignored due to low temperatures or high-speed loading, the differences in the amount of displacement, generated stress, and rigidity compared to the above-mentioned standards will all be even smaller. Therefore, assuming that no interlayer film is present is the largest estimate of the difference. Furthermore, if the first glass sheet and the second glass sheet are curved rather than flat, the change in rigidity due to sheet thickness will tend to be smaller due to geometric rigidity. Therefore, assuming that they are flat is the largest estimate of the difference.

[0120] The results of the above investigation are shown in Table 3 and in FIGS.

[0121]

[0122] From the results of Examples 2-1 to 2-9, even if the total thickness of the first glass plate and the second glass plate, i.e., the total weight, is the same, it was confirmed that the rigidity is increased by making the thickness of the first glass plate (t1) and the thickness of the second glass plate (t2) different. Specifically, compared to Example 2-8, in which t1 = t2 = 2.6 mm and the total thickness is 5.2 mm, t1 ≠ t2, and the total thickness is smaller in Example 2-2 (total thickness 4.7 mm) and Example 2-3 (total thickness 4.5 mm), the rigidity was higher. Furthermore, compared to Example 2-9, in which t1 = t2 = 2.3 mm and the total thickness is 4.6 mm, Example 2-5 (t1 = 3.5 mm, t2 = 1.1 mm), which has the same total thickness, had a higher rigidity. Furthermore, compared to the above Example 2-9, Example 2-2 (t1 = 4.0 mm, t2 = 0.7 mm), Example 2-3 (t1 = 4.0 mm, t2 = 0.5 mm), and Example 2-6 (t1 = 3.5 mm, t2 = 0.7 mm), which had total thicknesses similar to or less than 4.7 mm, 4.5 mm, and 4.2 mm, respectively, and where t1 ≠ t2, had higher rigidity, and in particular, Examples 2-2 and 2-3 had rigidity that was 2.5 times or more higher than that of Example 2-9. Note that, since Examples 2-2, 2-3, 2-5, and 2-6 actually have an interlayer film interposed between the two glass plates, they have better sound insulation than the single-pane Example 2-1.

[0123] From the above results, it was confirmed that the laminated glass for vehicles according to this embodiment has excellent strength and can prevent the occurrence of distortion by having two glass plates with a specific difference in thickness, with the first glass plate being a physically strengthened float glass having a specific thickness and the second glass plate being a chemically strengthened float glass having a specific thickness. It was also confirmed that the specific difference in thickness between the two glass plates can increase the rigidity of the laminated glass.

[0124] 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 present invention. This application is based on a Japanese patent application (Patent Application No. 2024-072662) filed on April 26, 2024, the contents of which are incorporated herein by reference.

[0125] REFERENCE SIGNS LIST 10 (vehicle) laminated glass 11 first glass plate 11a first main surface 11b second main surface 12 second glass plate 12a third main surface 12b fourth main surface 13 interlayer

Claims

1. A laminated glass for vehicles comprising a first glass sheet, a second glass sheet, and an interlayer film interposed between the first glass sheet and the second glass sheet, wherein the first glass sheet has opposing first and second main surfaces, with the second main surface facing the interlayer film; the second glass sheet has opposing third and fourth main surfaces, with the third main surface facing the interlayer film; the first glass sheet is curved so that the first main surface side is convex and the second main surface side is concave; the first glass sheet is made of physically strengthened float glass; the thickness of the first glass sheet is 3.1 to 5.0 mm; the first main surface and the second main surface of the first glass sheet each have a surface compressive stress value of 20 MPa or more; the second glass sheet is curved so that the third main surface side is convex and the fourth main surface side is concave; and the second glass sheet is made of chemically strengthened float glass. The thickness of the second glass plate is 0.4 to 1.3 mm.

2. The laminated glass for vehicles according to claim 1, wherein the third principal surface and the fourth principal surface of the second glass plate each have a surface compressive stress value of 400 to 900 MPa.

3. The laminated glass for vehicles according to claim 1 or 2, wherein the compressive stress layer depths of the third principal surface and the fourth principal surface of the second glass plate are each 50 μm or less.

4. The laminated glass for vehicles according to claim 1 or 2, wherein the second glass sheet has a higher tin content in the third main surface than in the fourth main surface.

5. The laminated glass for vehicles according to claim 1 or 2, wherein the second glass sheet has a tin content in the fourth main surface that is greater than the tin content in the third main surface.

6. The base composition of the second glass plate is expressed as a mass percentage based on oxides: SiO ２ :60~80%, Al ２ O ３ : 1-8%, Na ２ O: 5-20%, K ２ 3. The laminated glass for vehicles according to claim 1, wherein O: 0 to 5%, MgO: 4 to 12%, and CaO: 0 to 5%.

7. The laminated glass for vehicles according to claim 6, wherein the third principal surface and the fourth principal surface of the second glass plate each have a surface compressive stress value of 500 to 700 MPa, and the third principal surface and the fourth principal surface of the second glass plate each have a compressive stress layer depth of 40 μm or less.

8. The base composition of the second glass plate is expressed in mole percentage on an oxide basis as follows: SiO ２ :62~68%, Al ２ O ３ : 6-12%, Na ２ O: 9-17%, K ２ O: 0 to 7%, MgO: 7 to 13%, and ZrO ２ : Meets 0 to 0.8%, Na ２ O and K ２ The total content of O is ２ O ３ The laminated glass for vehicles according to claim 1 or 2, wherein the difference obtained by subtracting the content of 9. The laminated glass for vehicles according to claim 8, wherein the third principal surface and the fourth principal surface of the second glass plate each have a surface compressive stress value of 500 to 900 MPa, and the third principal surface and the fourth principal surface of the second glass plate each have a compressive stress layer depth of 28 μm or more.

10. The base composition of the second glass plate is expressed as a mass percentage based on oxides: SiO ２ :60~80%, Al ２ O ３ : 1-8%, Na ２ O: 5-20%, K ２ 3. The laminated glass for vehicles according to claim 1, wherein O: 0 to 5%, MgO: 0 to 7%, and CaO: 3 to 10%.

11. The laminated glass for vehicles according to claim 10, wherein the third principal surface and the fourth principal surface of the second glass plate each have a surface compressive stress value of 500 to 900 MPa, and the third principal surface and the fourth principal surface of the second glass plate each have a compressive stress layer depth of 20 μm or less.

12. A laminated glass for vehicles according to claim 1 or 2, wherein the first glass sheet is bent by hot bending so that the first main surface side is curved convexly and the second main surface side is curved concavely, and the second glass sheet is bent by cold bending so that the third main surface side is curved convexly and the fourth main surface side is curved concavely.

13. The laminated glass for vehicles according to claim 1 or 2, wherein the difference in thickness between the first glass sheet and the second glass sheet is 2.0 mm or more.

14. The laminated glass for vehicles according to claim 1 or 2, which is used as a door glass for an automobile.

15. The laminated glass for a vehicle according to claim 1 or 2, wherein the first glass sheet is disposed on the vehicle exterior side and the second glass sheet is disposed on the vehicle interior side.

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