Method for manufacturing laminated glass and PVB layer, and method for manufacturing laminated glass

Abstract

The present invention suppresses a degradation in the viewability of a HUD image. This laminated glass (1) comprises: a first glass base body (12); a second glass main body (14); a reflective layer (16) provided between the first glass main body (12) and the second glass main body (14); and a PVB layer (20) which is provided between the second glass base body (14) and the reflective layer (16) and is composed of a polyvinyl butyral resin. In the laminated glass (1), the thickness (D5) of the PVB layer (20) is 2-25 μｍ, the longitudinal radius of curvature of the laminated glass (1) is no greater than 20,000 mm, the transverse radius of curvature of the laminated glass (1) is no greater than 10,000 mm, and the bubble remaining rate of the laminated glass (1) is no greater than 2%.

Description

Technical Field

[0001] The present invention relates to a laminated glass, a method for manufacturing a PVB layer, and a method for manufacturing a laminated glass.

Background Art

[0002] In recent years, the introduction of a head-up display (HUD) that reflects an image on glass such as a vehicle to display predetermined information in the driver's field of view has been progressing. For example, Patent Document 1 describes a laminated glass provided with a half mirror between an inner glass and an outer glass.

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For such a laminated glass for displaying a HUD image, suppression of a decrease in visibility of the displayed HUD image is required.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a laminated glass, a method for manufacturing a PVB layer, and a method for manufacturing a laminated glass capable of suppressing a decrease in visibility of a HUD image.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the laminated glass according to the present disclosure comprises a first glass substrate, a second glass substrate, a reflective layer provided between the first glass substrate and the second glass substrate, and a PVB layer provided between the second glass substrate and the reflective layer and formed of polyvinyl butyral resin, wherein the thickness of the PVB layer is 2 μm or more and 25 μm or less, the longitudinal radius of curvature of the laminated glass is 20,000 mm or less, the transverse radius of curvature of the laminated glass is 10,000 mm or less, and the bubble retention rate of the laminated glass is 2% or less.

[0007] To solve the above-mentioned problems and achieve the objective, the method for manufacturing a PVB layer according to the present disclosure includes the steps of: applying a coating solution, which is a liquid to which polyvinyl butyral resin is added, to the surface of a substrate on which irregularities are formed on the surface; and drying the coating solution to form a PVB layer, which is a layer of polyvinyl butyral resin, having a thickness of 30 μm or less, a maximum height Rz on the substrate side surface of 5 μm or more, and a ratio of the maximum height Rz to the thickness of less than 0.95.

[0008] To solve the above-mentioned problems and achieve the objective, the method for manufacturing laminated glass according to this disclosure involves laminating the PVB layer manufactured by the method for manufacturing the PVB layer, a reflective layer, a first glass substrate, and a second glass substrate to manufacture laminated glass. [Effects of the Invention]

[0009] According to the present invention, the decrease in the visibility of the HUD image can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of laminated glass according to this embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view of the laminated glass according to this embodiment. [Figure 3] Figure 3 illustrates the bubble retention rate. [Figure 4]Figure 4 is a diagram illustrating the manufacturing method of the PVB layer. [Figure 5] Figure 5 is a schematic diagram showing the PVB layer before lamination. [Figure 6] Figure 6 is a diagram illustrating the manufacturing method of laminated glass. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Note that the present invention is not limited to these embodiments, and if there are multiple embodiments, they may be constructed by combining these embodiments. Numerical values ​​are rounded to the nearest whole number.

[0012] (Laminated glass) Figure 1 is a schematic diagram of laminated glass according to this embodiment. The laminated glass 1 according to this embodiment shown in Figure 1 is mounted on a vehicle. Laminated glass 1 is a window member applied to the windshield of a vehicle, in other words, it is used as the front windshield of a vehicle, or in other words, as a windshield. The interior of a vehicle (inside the vehicle) refers to, for example, the interior of the vehicle where the driver's seat is located. However, the use of laminated glass 1 is not limited to the windshield of a vehicle and is arbitrary, and it can be applied to other parts of the vehicle. Hereinafter, the upper edge of the laminated glass 1 will be referred to as the upper edge portion 1a, the lower edge as the lower edge portion 1b, one side edge as the side edge portion 1c, and the other side edge as the side edge portion 1d. The upper edge portion 1a is the edge portion located on the vertically upper side when the laminated glass 1 is mounted on a vehicle. The lower edge portion 1b is the edge portion located on the vertically lower side when the laminated glass 1 is mounted on a vehicle. The side edge portion 1c is the edge portion located on one side when the laminated glass 1 is mounted on a vehicle. The side edge portion 1d is the edge portion located on the other side when the laminated glass 1 is mounted on the vehicle.

[0013] Hereinafter, among the directions parallel to the surface of the laminated glass 1, the direction from the lower edge 1b toward the upper edge 1a will be defined as the Y direction (vertical direction), and the direction from the side edge 1c toward the side edge 1d will be defined as the X direction (horizontal direction). In this embodiment, the X direction and the Y direction are orthogonal. Furthermore, the direction perpendicular to the surface of the laminated glass 1, in other words, the thickness direction of the laminated glass 1, will be defined as the Z direction. The Z direction is, for example, the direction from the outside of the vehicle toward the inside of the vehicle when the laminated glass 1 is mounted on a vehicle. Note that the X direction and the Y direction are along the surface of the laminated glass 1, but if the surface of the laminated glass 1 is curved, for example, they may be directions that are tangent to the surface of the laminated glass 1 at the center point O of the laminated glass 1. Note that the center point O is the center position of the laminated glass 1 when viewed from the Z direction.

[0014] Laminated glass 1 has a light-transmitting region A1 and a light-blocking region A2. Light-transmitting region A1 is the central part of laminated glass 1 when viewed from the Z direction and is the region that ensures the driver's field of view. Light-transmitting region A1 is the region that transmits visible light. Light-blocking region A2 is the region that is formed around light-transmitting region A1 when viewed from the Z direction. Light-blocking region A2 is the region that blocks visible light. Within light-blocking region A2, there may be a far-infrared transmitting region that transmits far-infrared light and is used to install a far-infrared camera, or a visible light transmitting region that transmits visible light and is used to install a visible light camera.

[0015] A HUD region AH is formed in the light-transmitting region A1. The HUD region AH is the region illuminated by light from a projection device (not shown), and is the region where the HUD image, which is the image projected from the projection device, is displayed. The projection device is a device that projects an image for the HUD onto the laminated glass 1, i.e., a projector. The projection device is positioned so as to overlap with the HUD region AH when viewed from the optical axis direction of the projection device. The HUD region AH is formed on the X side of the center point O, and in the example of Figure 1, it is formed on the side edge 1d side and the lower edge 1b side of the center point O. However, the position and size of the HUD region AH are arbitrary, and for example, it may be formed on the side edge 1c side of the center point O. Also, multiple HUD regions AH may be formed. Furthermore, the HUD region AH can also be described as the range in which light from the mirrors constituting the HUD is illuminated onto the windshield when the mirrors constituting the HUD, which are placed inside the vehicle, are rotated in an eyebox based on SAE-J1757-2 (2018).

[0016] The laminated glass 1 preferably has a radius of curvature in the Y direction (vertical direction) of 20,000 mm or less, and a radius of curvature in the Y direction of 4,000 mm or more. More preferably, the radius of curvature in the Y direction of the laminated glass 1 is between 6,000 mm and 20,000 mm. The laminated glass 1 preferably has a radius of curvature in the X direction (horizontal direction) of 10,000 mm or less, and a radius of curvature in the X direction of 1,000 mm or more. More preferably, the radius of curvature in the X direction of the laminated glass 1 is between 1,500 mm and 6,000 mm. Here, the radius of curvature in the Y direction refers to the radius of curvature of the curve extending in the Y direction along the surface of the laminated glass 1, and the radius of curvature in the X direction refers to the radius of curvature of the curve extending in the X direction along the surface of the laminated glass 1. It is preferable that the radius of curvature of the laminated glass 1 throughout its entire surface is within the range of the above radii of curvature. The radius of curvature is determined by measuring the shape at a predetermined pitch, for example, 20 mm pitch, across the entire surface of the laminated glass 1 and converting it to the radius of curvature in the Y or X direction.

[0017] The length of the laminated glass 1 in the Y direction, that is, the length along the Y direction from the upper edge 1a to the lower edge 1b, is preferably 200 mm to 2500 mm, preferably 200 mm to 2000 mm, and more preferably 200 mm to 1500 mm. Here, the length of the laminated glass 1 in the Y direction refers to the length in the Y direction at the longest point. The length of the laminated glass 1 in the X direction, that is, the length along the X direction from the side edge 1c to the side edge 1d, is preferably 200 mm to 2500 mm, preferably 200 mm to 2300 mm, and more preferably 200 mm to 2000 mm. Here, the length of the laminated glass 1 in the X direction refers to the length in the X direction at the longest point.

[0018] Figure 2 is a schematic cross-sectional view of the laminated glass according to this embodiment. Figure 2 is a cross-sectional view of the laminated glass 1 as seen from the Y direction. As shown in Figure 2, the laminated glass 1 has a first glass substrate 12, a second glass substrate 14, a reflective layer 16, an intermediate layer 18, a PVB layer 20, and a light-shielding layer 22. The laminated glass 1 is stacked in the Z direction in the order of the first glass substrate 12, intermediate layer 18, reflective layer 16, PVB layer 20, second glass substrate 14, and light-shielding layer 22. The laminated glass 1 displays a HUD image by reflecting light from the projection device with the reflective layer 16 formed in the HUD area AH.

[0019] (Glass substrate) The first glass substrate 12 is a glass substrate on the vehicle outer side. As the first glass substrate 12, for example, soda lime glass, aluminosilicate, organic glass can be used, but it is not limited thereto. The thickness D1 of the first glass substrate 12 is preferably 1.8 mm or more and 3.0 mm or less, and more preferably 1.9 mm or more and 2.3 mm or less. By making the thickness D1 of the first glass substrate 12 within this range, while appropriately maintaining the resistance performance against flying stones and the like, it is possible to suppress an increase in weight and a decrease in formability. The thickness D1 is the length of the first glass substrate 12 in the Z direction, and hereinafter, unless otherwise specified, the thickness refers to the length in the Z direction.

[0020] The second glass substrate 14 is a glass substrate on the vehicle inner side. As the second glass substrate 14, similar to the first glass substrate 12, for example, soda lime glass, aluminosilicate, organic glass can be used, but it is not limited thereto. The thickness D2 of the second glass substrate 14 is preferably 0.3 mm or more and 2.3 mm or less, and more preferably 0.4 mm or more and 2.0 mm or less. When the thickness of the second glass substrate 14 is 0.3 mm or more, it is easy to handle during manufacturing and assembly. By making the thickness D2 of the second glass substrate 14 within this range, it does not become thicker than the thickness D1 of the first glass substrate 12, and it is less likely to cause a mismatch when the first glass substrate 12 and the second glass substrate 1 are laminated after bending into the panel shape, and the followability to the PVB layer can be appropriately maintained.

[0021] (Reflection layer) The reflective layer 16 is provided between the first glass substrate 12 and the second glass substrate 14 in the Z direction. The reflective layer 16 is a layer that reflects the light irradiated from the projection device to the HUD region AH. The reflective layer 16 is transparent to visible light. In the present embodiment, since the light of P polarization is irradiated from the projection device, it can be said that the reflective layer 16 is a P-polarization reflection film that reflects the light of P polarization. The reflective layer 16 is formed, for example, by laminating a plurality of members such as polymers having different refractive indexes in the Z direction. The reflective layer 16 preferably has a reflectance of 5% or more for P polarization at the Brewster angle in a state where the reflective layer 16 is encapsulated in the laminated glass 1. If the reflectance of P polarization is 5% or more, the HUD image can be appropriately visually recognized. Note that the reflective layer 16 is not limited to being a P-polarization reflection film, and may be, for example, a hologram film, a scattering type transparent screen, a high-reflection film for HUD, or the like. Also, for example, the reflective layer 16 includes a first layer (for example, a quarter-wave plate) that converts the incident P polarization into circular polarization, and a second layer (for example, a cholesteric liquid crystal layer) that selectively reflects the circular polarization, and the first layer may be configured to convert the circular polarization reflected by the second layer into P polarization and emit it.

[0022] The thickness D3 of the reflective layer 16 is preferably 25 μm or more and 200 μm or less, and more preferably 40 μm or more and 100 μm or less. By making the thickness D3 within this range, the light from the projection device can be appropriately reflected and the external light can be appropriately transmitted. In the present embodiment, the reflective layer 16 is provided over the entire area of the laminated glass 1 when viewed from the Z direction, but it may be provided only in the HUD region AH, for example. That is, the reflective layer 16 may be formed at least in the HUD region AH of the entire area of the laminated glass 1.

[0023] (Intermediate layer) The intermediate layer 18 is provided between the first glass substrate 12 and the reflective layer 16 in the Z direction. The intermediate layer 18 adheres to the first glass substrate 12 on the outer surface of the vehicle and to the reflective layer 16 on the inner surface of the vehicle, thereby bonding the first glass substrate 12 and the reflective layer 16. The intermediate layer 18 is formed of PVB (Poly Vinyl Butyral), that is, polyvinyl butyral resin. Polyvinyl butyral resin is a thermoplastic resin obtained, for example, by reacting polyvinyl alcohol with n-butyraldehyde.

[0024] The thickness D4 of the intermediate layer 18 is greater than the thickness D5 of the PVB layer 20 described later. The thickness D4 of the intermediate layer 18 is preferably 0.3 mm or more and 15 mm or less, more preferably 0.3 mm or more and 3 mm or less, and even more preferably 0.7 mm or more and 1 mm or less. By keeping the thickness of the intermediate layer 18 within this range, the safety performance required for laminated glass is ensured while suppressing an increase in weight that would make handling difficult during manufacturing and assembly.

[0025] The intermediate layer 18 is not limited to being made of polyvinyl butyral resin, but may be composed of any material such as EVA (Ethylene Vinyl Acetate) or COP (Cyclo Olefin Polymer). The intermediate layer 18 may also have a coating that has the function of absorbing ultraviolet rays or infrared rays. The portion of the intermediate layer 18 corresponding to the upper edge 1a of the laminated glass 1 may be colored. The intermediate layer 18 may have three or more layers, such as a sound-insulating PVB in which a sound-insulating layer is sandwiched between layers of PVB. When the intermediate layer 18 has three or more layers, the thickness of the core layer located in the center in the thickness direction is preferably 70 μm to 130 μm, more preferably 80 μm to 120 μm, and even more preferably 90 μm to 110 μm. Setting the core layer to this thickness suppresses a decrease in the sound-insulating function of the intermediate layer 18.

[0026] (PVB layer) The PVB layer 20 is provided between the second glass substrate 14 and the reflective layer 16 in the Z direction. The PVB layer 20 has the function of bonding the reflective layer 16 and the second glass substrate 14 by adhering to the reflective layer 16 on the outer surface of the vehicle and to the second glass substrate 14 on the inner surface of the vehicle. The PVB layer 20 is made of PVB, i.e., polyvinyl butyral resin.

[0027] The thickness D5 of the PVB layer 20 is 2 μm or more and 25 μm or less, preferably 4 μm or more and 25 μm or less, and more preferably 4 μm or more and 20 μm or less. By having a thickness D5 within this range, it is possible to suppress the decrease in visibility of the HUD image, known as orange peel, while also suppressing the decrease in adhesion to the second glass substrate 14 and the reflective layer 16. Note that the thickness D5 here refers to the thickness of the PVB layer 20 when it is laminated on the laminated glass 1. As described later, the PVB layer 20 is laminated with irregularities formed on its surface, so when it is pressed by the reflective layer 16 and the second glass substrate 14 during lamination, the irregular surface deforms, and the thickness D5 when laminated falls within the above numerical range.

[0028] In this embodiment, since the reflective layer 16 is formed over the entire area, the PVB layer 20 and the intermediate layer 18 are separated by the reflective layer 16 throughout the entire area. However, if the reflective layer 16 is not formed over the entire area, the PVB layer 20 and the intermediate layer 18 may be bonded together and form a single unit in the areas where the reflective layer 16 is not formed.

[0029] (light shielding layer) The light-shielding layer 22 is provided on the inner surface of the second glass substrate 14. The light-shielding layer 22 is a layer that blocks visible light. For example, a ceramic light-shielding layer or a light-shielding film can be used as the light-shielding layer 22. For example, a ceramic layer made of conventionally known materials such as a black ceramic layer can be used as the ceramic light-shielding layer. For example, a light-shielding polyethylene terephthalate (PET) film, a light-shielding polyethylene naphthalate (PEN) film, or a light-shielding polymethyl methacrylate (PMMA) film can be used as the light-shielding film. Note that the light-shielding layer 22 is not limited to being provided on the inner surface of the second glass substrate 14, but may also be provided on the outer surface of the first glass substrate 12, or may be formed between the first glass substrate 12 and the second glass substrate 14.

[0030] The light-shielding region A2 is formed by providing a light-shielding layer 22 to the laminated glass 1. In other words, the light-shielding region A2 is the region where the light-shielding layer 22 is provided. On the other hand, the light-transmitting region A1 is the region where the glass substrates 12 and 14 do not have the light-shielding layer 22.

[0031] (Bubble retention rate) Figure 3 is a diagram illustrating the bubble retention rate. In laminated glass 1 with the above configuration, the bubble retention rate is preferably 2% or less, preferably 1% or less, and more preferably 0%. By having the bubble retention rate within this numerical range, a decrease in visibility can be suppressed. It is particularly preferable that the bubble retention rate in the HUD area AH be within this numerical range. The bubble retention rate refers to the degree to which bubbles remain in the laminated glass 1. A bubble is a bubble that exists between the first glass substrate 12 and the second glass substrate 14, for example, a bubble that remained between the PVB layer 20 and the second glass substrate 14 during the manufacturing process without being able to be degassed. Furthermore, it is preferable that the size of the individual bubbles is 2 mm or less in diameter. If the diameter of the bubbles is 2 mm or less, it will have little effect on visibility. Furthermore, it is preferable that the diameter of the bubbles is 1 mm or less. If the bubble is not circular when viewed from the Z direction, it may be treated as the diameter of the circumscribed circle of the bubble when viewed from the Z direction. In this embodiment, areas where the PVB layer 20 does not become transparent and appears cloudy due to poor adhesion between the PVB layer 20 and the second glass substrate 14 are considered to be clusters of small bubbles. Areas where the PVB layer 20 has uneven surfaces and appears hazy are also considered to be clusters of small bubbles. The area of ​​such areas is calculated and considered as the area of ​​bubbles, and the bubble retention rate is determined. Let's explain the bubble retention rate in more detail. As shown in Figure 3, a 100 mm square area at an arbitrary position on the surface of the laminated glass 1, viewed from the Z direction (in a plan view), is defined as region 1H. Light is shone onto the laminated glass 1, and the presence of bubbles in region 1H is confirmed when viewed from the Z direction. For example, the laminated glass 1 can be illuminated with a high-intensity lamp and confirmed by reflection from the bubbles, or light can be shone from the edge of the laminated glass 1 and confirmed by scattering the light from the bubbles. Alternatively, the image of the bubbles can be confirmed by shining light from the opposite side of the laminated glass 1, or the bubbles can be confirmed with a laser microscope. For example, in Figure 3, bubbles c exist in the first region 1Ha, but no bubbles exist in the second region 1Hb, which does not overlap with the first region 1Ha. In this case, the bubble retention rate of the first region 1Ha is calculated as the ratio of the area of ​​all bubbles c in region 1Ha to the area of ​​region 1Ha when viewed from the Z direction. Since there are no bubbles c in region 1Hb, the bubble retention rate is zero. Since region 1H is any region, the bubble retention rate of the laminated glass 1 as a whole will be within the above range. However, it is not necessary to measure the entire laminated glass 1 as surface 1H; only the 100mm square region with the most bubbles remaining in the entire laminated glass 1 may be measured as surface 1H. Alternatively, the HUD region AH may be used for the determination. For example, region 1Ha shown in the example in Figure 3 may overlap with the HUD region AH.

[0032] The laminated glass 1 according to this embodiment displays a HUD image by reflecting light from a projection device with a reflective layer 16. The inventors have found that if the PVB layer 20 between the reflective layer 16 and the second glass substrate 14 is thick, a phenomenon called orange peel occurs, which reduces the visibility of the HUD image. In contrast, the laminated glass 1 according to this embodiment suppresses orange peel and reduces the decrease in HUD image visibility by making the thickness D5 of the PVB layer 20 25 μm or less, while ensuring adhesion by making it 2 μm or more. Furthermore, since the bubble retention rate of the laminated glass 1 according to this embodiment is 2% or less, a decrease in the visibility of the glass can be suppressed. Moreover, in laminated glass with a double-bent shape that is curved in the X and Y directions, it is difficult to remove bubbles when laminating each component, and bubbles tend to remain. In contrast, the laminated glass 1 according to this embodiment, by providing a PVB layer 20, can properly remove bubbles during lamination and reduce the bubble retention rate.

[0033] (Method for manufacturing the PVB layer) Next, the manufacturing method for the laminated glass 1 described above will be explained. Figure 4 is a diagram illustrating the manufacturing method for the PVB layer. In this manufacturing method, as shown in Figure 4, a forming substrate B2 is prepared on a substrate B1. The forming substrate B2 has an embossed surface B2a opposite to the substrate B1. In this manufacturing method, as shown in step S10 of Figure 4, a coating liquid 20A is applied to the surface B2a of the forming substrate B2. The coating liquid 20A is a liquid in which PVB resin, which is the material for the PVB layer 20, is added as a solid component to ethanol as a solvent. Preferably, the amount of PVB resin added to the coating liquid 20A is 6% or more and 15% or less by mass ratio of the total amount of the coating liquid 20A. Note that the solvent is not limited to ethanol and may be a liquid with any component. In addition, a silane agent may be added to the coating liquid 20A as an additive. The amount of coating liquid 20A applied to the substrate B2 is set so that the thickness D5 of the PVB layer 20 when laminated on the laminated glass 1 falls within the above numerical range.

[0034] After applying the coating solution 20A to the surface B2a of the forming substrate B2, the liquid component of the coating solution 20A is removed by drying, as shown in step S12 of Figure 4, to form the PVB layer 20 before lamination onto the laminated glass 1. Before lamination, the surface 20a of the PVB layer 20 that is in contact with the surface B2a of the forming substrate B2 has irregularities (embossing). The surface 20b of the PVB layer 20 opposite to surface 20a does not need to have irregularities formed on it and may have any shape.

[0035] Figure 5 is a schematic diagram showing the PVB layer before lamination. As shown in Figure 5, the thickness of the PVB layer 20 before lamination is defined as thickness D5a. Thickness D5a refers to the thickness of the thickest part of the PVB layer 20 before lamination, or in other words, the length in the Z direction between the part that protrudes from surface 20a at the position furthest from surface 20b and the part that protrudes from surface 20b at the position furthest from surface 20a. In this case, thickness D5a is 30 μm or less, preferably 25 μm or less, and more preferably 10 μm or less. Furthermore, thickness D5a is preferably 6.2 μm or more, more preferably 6.4 μm or more, and even more preferably 6.6 μm or more. By setting thickness D5a within this numerical range, it becomes possible to set the thickness D5 after lamination within the above numerical range, thereby ensuring adhesion while suppressing a decrease in the visibility of the HUD image.

[0036] As shown in Figure 5, the thickness (height) of the portion of the PVB layer 20 with irregularities before lamination is defined as thickness D6a. Thickness D6a refers to the length in the Z direction between the portion of the PVB layer 20 surface 20a that is furthest from surface 20b and the portion of the PVB layer 20 surface 20a that is closest to surface 20b. In other words, thickness D6a can also be said to be the maximum height (maximum height roughness) Rz of surface 20a as defined in JIS B 0601. In this case, thickness D6a is 5 μm or more, and more preferably 5.4 μm or more. Furthermore, it is preferable that thickness D6a is thinner than the thickness D5 of the PVB layer 20 before lamination. By setting thickness D5a within this numerical range, irregularities can be appropriately formed, air bubbles can be appropriately removed during lamination, and the air bubble retention rate of the laminated glass 1 can be reduced. Furthermore, thicknesses D5a and D6a represent the thickness of the PVB layer 20 before lamination, under conditions where pressure higher than atmospheric pressure is not applied.

[0037] Furthermore, the ratio of thickness D6a to thickness D5a is defined as the thickness ratio. In this case, the thickness ratio is less than 0.95, more preferably 0.82 or less, and even more preferably 0.63 or less. Also, the thickness ratio is preferably 0.18 or more, more preferably 0.22 or more, and even more preferably 0.27 or more. By setting the thickness ratio within this range, it is possible to thin the PVB layer 20 while considering the deterioration of image clarity, while ensuring the thickness of the non-irregular areas and suppressing damage to the PVB layer before lamination.

[0038] Furthermore, the arithmetic mean roughness Ra of the surface 20a of the PVB layer 20 before lamination, as defined in JIS B 0601, is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 10 μm or less, and even more preferably 0.5 μm or more and 5 μm or less. By setting Ra within this range, the unevenness can be appropriately formed over the entire surface 20a, thereby reducing the rate of air bubbles remaining in the laminated glass 1. In other words, by having an arithmetic mean roughness Ra of the surface 20a of the PVB layer 20 between 0.1 μm and 10 μm, air release properties can be maintained, and the remaining uneven shape after pressing onto the glass substrate can be suppressed.

[0039] Furthermore, the shape and dimensions of the surface irregularities 20a of the PVB layer 20 before lamination will be the same as the shape and dimensions of the surface irregularities B2a of the substrate B2. Therefore, the thickness D5a, D6a, and surface roughness of the surface 20a of the PVB layer 20 before lamination, as described above, are determined by the shape and dimensions of the surface B2a of the substrate B2.

[0040] (Manufacturing method for laminated glass) Next, a method for manufacturing laminated glass 1 using the PVB layer 20 manufactured by the method described above will be explained. Figure 6 is a diagram illustrating the manufacturing method of laminated glass. In this manufacturing method, laminated glass 1 is manufactured by laminating the PVB layer 20 manufactured as described above, a reflective layer 16, a first glass substrate 12, a second glass substrate 14, and an intermediate layer 18. Specifically, as shown in step S6 of Figure 6, the surface 16a of the reflective layer 16 is brought into contact with the surface 20b of the PVB layer 20 before lamination, which is formed on the surface B2a of the forming substrate B2, thereby bonding the surface 20b and the surface 16a. As a result, the reflective layer 16 and the PVB layer 20 are bonded and laminated. When bonding the reflective layer 16 and the PVB layer 20, a pressure bonding process is used in which the reflective layer 16 and the PVB layer 20 are heated and pressurized under conditions such as a temperature of 80°C or higher, preferably 100°C or higher, and a temperature of 150°C or lower, preferably 130°C or lower, a pressure of 0.6 MPa or higher, preferably 1.0 MPa or higher, and a pressure of 3.0 MPa or lower, preferably 1.5 MPa or lower.

[0041] Next, as shown in step S22 of Figure 6, the forming substrate B2 is removed from the PVB layer 20 laminated on the reflective layer 16. This exposes the surface 20a of the PVB layer 20 with its uneven surface. Any method may be used to remove the forming substrate B2 from the PVB layer 20.

[0042] Next, as shown in step S24 of Figure 6, the laminate of the reflective layer 16 and the PVB layer 20 is laminated with the first glass substrate 12, the second glass substrate 14, and the intermediate layer 18. The surfaces 18a and 18b of the intermediate layer 18 have irregularities formed on them. The shape and dimensions of the irregularities on surfaces 18a and 18b may be arbitrary, but they may be similar in shape and dimensions to, for example, the surface 20a of the PVB layer 20. When performing the lamination, the surface 18a of the intermediate layer 18 is brought into contact with the surface 16b of the reflective layer 16 opposite to the surface 16a, and surfaces 18a and 16b are bonded together. The pressure and temperature conditions when bonding surfaces 18a and 16b may be the same as those when bonding the reflective layer 16 and the PVB layer 20. Furthermore, the surface 18b of the intermediate layer 18 opposite to the surface 18a is brought into contact with the inner surface 12a of the first glass substrate 12, thereby bonding the surfaces 18b and 12a. Also, the surface 14b of the second glass substrate 14 opposite to the inner surface 14a is brought into contact with the surface 20a of the PVB layer 20, thereby bonding the surfaces 14b and 20a. As a result, a laminate of the reflective layer 16 and the PVB layer 20 is laminated with the first glass substrate 12, the second glass substrate 14, and the intermediate layer 18. Specifically, the laminate of the intermediate layer 18, the reflective layer 16, and the PVB layer 20 is sandwiched between the first glass substrate 12 and the second glass substrate 14 to form a glass laminate. This glass laminate is then placed in a rubber bag and bonded in a vacuum with a pressure of -65kPa to -100kPa at a temperature of approximately 70°C to 130°C. Furthermore, a bonding process may be performed by heating and pressurizing under conditions such as a pressure of 0.6 MPa to 1.5 MPa and a temperature of 100°C to 150°C. In step S24, the flat first glass substrate 12 and the second glass substrate 14 may each be bent, and a laminate of the intermediate layer 18, reflective layer 16, and PVB layer 20 may be sandwiched between the bent first glass substrate 12 and the second glass substrate 14 for lamination. Alternatively, an additional PVB layer 20 may be laminated between the laminate of the reflective layer 16 and PVB layer 20 and the second glass substrate 14. Laminating multiple PVB layers 20 makes it easier to adjust the film thickness.

[0043] Thus, in step S24, after forming a laminate of the intermediate layer 18, the reflective layer 16, and the PVB layer 20, the laminate is sandwiched between the first glass substrate 12 and the second glass substrate 14, and the lamination is carried out. However, the order of lamination of each component and the conditions for lamination in step S24 are not limited to the above description and may be arbitrary.

[0044] By laminating each component in step S24, laminated glass 1 is manufactured as shown in step S26. If a light-shielding layer 22 is to be provided, the light-shielding layer 22 may be formed, and other layers may be laminated as needed.

[0045] Thus, in the manufacturing method according to this embodiment, the PVB layer 20 is made thinner before lamination, and irregularities are formed on the surface 20a, thereby suppressing a decrease in the visibility of the HUD image while ensuring adhesion and reducing the rate of air bubbles remaining in the laminated glass 1.

[0046] (Effects of this embodiment) As described above, the laminated glass 1 according to this embodiment comprises a first glass substrate 12, a second glass substrate 14, a reflective layer 16 provided between the first glass substrate 12 and the second glass substrate 14, and a PVB layer 20 provided between the second glass substrate 14 and the reflective layer 16 and formed of polyvinyl butyral resin. The laminated glass 1 has a PVB layer 20 thickness D5 of 2 μm or more and 25 μm or less, a radius of curvature in the Y direction (vertical direction) of 20,000 mm or less, a radius of curvature in the X direction (horizontal direction) of 10,000 mm or less, and a bubble retention rate of 2% or less. In the laminated glass 1 according to this embodiment, by making the thickness D5 of the PVB layer 20 thin to 25 μm or less, orange peel is suppressed and the decrease in visibility of the HUD image is suppressed, while by making it 2 μm or more, adhesion by the PVB layer 20 is ensured. Furthermore, since the laminated glass 1 according to this embodiment has a bubble retention rate of 2% or less, a decrease in the visibility of the glass can be suppressed. Moreover, in laminated glass with a double-bent shape that is curved in the X and Y directions, it is difficult for bubbles to escape when laminating each component, and bubbles tend to remain. In contrast, the laminated glass 1 according to this embodiment has a PVB layer 20, which allows for the proper removal of bubbles during lamination, thereby reducing the bubble retention rate. It should be noted that the laminated glass 1 is preferably manufactured by the manufacturing method described above, but it is not limited to the above manufacturing method and may be manufactured by any method.

[0047] Furthermore, it is preferable that the laminated glass 1 further comprises an intermediate layer 18 made of polyvinyl butyral resin, provided between the first glass substrate 12 and the reflective layer 16. The intermediate layer 18 is thicker than the PVB layer 20. In this embodiment, the laminated glass 1 can maintain appropriate strength by providing an intermediate layer 18 that is thicker than the PVB layer 20.

[0048] Furthermore, the laminated glass 1 preferably has a PVB layer 20 thickness D5 of 4 μm or more and 25 μm or less, and more preferably has a PVB layer 20 thickness D5 of 4 μm or more and 20 μm or less. This makes it possible to more effectively suppress the decrease in the visibility of the HUD image.

[0049] Furthermore, it is preferable that the laminated glass 1 has a length of 200 mm or more in the X and Y directions. By providing a PVB layer 20 to laminated glass 1 of such a large size, where air bubbles are difficult to escape, the rate of remaining air bubbles can be reduced.

[0050] Furthermore, the method for manufacturing the PVB layer according to this embodiment includes the steps of: applying a coating solution 20A, which is a liquid to which polyvinyl butyral resin is added, to the surface B2a of a substrate (forming substrate B2) on which irregularities are formed on the surface B2a; and drying the coating solution 20A to form a PVB layer 20 of polyvinyl butyral resin, in which the thickness D5a is 30 μm or less, the maximum height Rz (thickness D6a) of the substrate-side surface 20a is 5 μm or more, and the ratio of the maximum height Rz (thickness D6a) to the thickness D5a (thickness ratio) is less than 0.95. According to this manufacturing method, by setting the thickness D5a to 30 μm or less, it is possible to reduce the thickness of the PVB layer 20 after lamination, thereby suppressing a decrease in the visibility of the HUD image. In addition, by setting the maximum height Rz to 5 μm or more, appropriate irregularities can be formed on the surface 20a, thereby reducing the rate of remaining air bubbles. Furthermore, by setting the thickness ratio to less than 0.95, the thickness of the areas where no irregularities are formed can be ensured, thereby maintaining the strength of the PVB layer 20.

[0051] Furthermore, in the step of forming the PVB layer 20, it is preferable to form a PVB layer 20 with a thickness D5a of 25 μm or less. By setting the thickness D5a within this range, the decrease in the visibility of the HUD image can be effectively suppressed.

[0052] Furthermore, in the step of forming the PVB layer 20, it is preferable to form a PVB layer 20 with a maximum height Rz of 5.4 μm or more. By setting the maximum height Rz within this range, the rate of remaining air bubbles can be reduced.

[0053] Furthermore, in the step of forming the PVB layer 20, it is preferable to form a PVB layer 20 with a ratio (thickness ratio) of 0.82 or less. By keeping the thickness ratio within this range, the strength of the PVB layer 20 can be maintained.

[0054] Furthermore, the manufacturing method for the laminated glass 1 according to this embodiment involves laminating the PVB layer 20 manufactured by the above method, the reflective layer 16, the first glass substrate 12, and the second glass substrate 14 to produce the laminated glass 1. This manufacturing method suppresses the decrease in visibility of the HUD image, reduces the rate of remaining air bubbles, and maintains the strength of the PVB layer 20.

[0055] Furthermore, the manufacturing method for laminated glass 1 includes the steps of: bonding the surface 20b of the PVB layer 20 opposite to the substrate (forming substrate B2) to the reflective layer 16; removing the substrate (forming substrate B2) from the PVB layer 20 bonded to the reflective layer 16; bonding a second glass substrate 14 to the surface 20a of the PVB layer 20 opposite to the reflective layer 16; and laminating a first glass substrate 12 on the surface 16b of the reflective layer 16 opposite to the PVB layer 20. This manufacturing method suppresses a decrease in the visibility of the HUD image, reduces the rate of remaining air bubbles, and maintains the strength of the PVB layer 20.

[0056] (Examples) Examples are described below. Examples 1 to 11 evaluated the visibility and image clarity due to bubbles by varying the adhesive layer material, the thickness of the adhesive layer after lamination, the glass size (length) in the vertical and horizontal directions, the radius of curvature of the glass in the vertical and horizontal directions, and the bubble retention rate. The adhesive layer is the layer corresponding to the PVB layer 20 in this embodiment. The layers other than the adhesive layer were common to all examples. The laminated glass was constructed by laminating a first glass substrate, an intermediate layer, a reflective layer, an adhesive layer, and a second glass substrate in that order. A glass plate with a thickness of 2.0 mm and an intermediate layer with a thickness of 0.76 mm were used, and embossing was applied to create a textured surface to prevent bubbles from remaining due to the intermediate layer. For the bubble retention rate, the ratio of the area of ​​bubbles in a 100 mm square area where the most bubbles remained in the entire laminated glass was calculated as the bubble retention rate. Visibility due to air bubbles was assessed as follows: a bubble retention rate of 2% or less was marked as a success (✓), and a bubble retention rate greater than 2% was marked as a failure (✗). Image clarity was evaluated by projecting a horizontal line with a width of 0.034 degrees (=2 min) onto laminated glass at a distance of 2 m, and checking whether the "vertical distortion of the line" exceeded 0.017 degrees. A score of "good" was given if the "vertical distortion of the line" did not exceed 0.017 degrees (=1 min), and a score of "bad" was given if it exceeded 0.017 degrees (=1 min).

[0057] (Example 1) In Example 1, the laminated glass used PVB as the adhesive layer, with a thickness of 2 μm after lamination. The surface of the adhesive layer was embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, and the radius of curvature in the horizontal direction was 10000 mm. The sample had a bubble retention rate of 1%. For example, by embossing (uneven) the surface of the adhesive layer before lamination, the bubble retention rate can be reduced to 2% or less. However, embossing is not the only method that can reduce the bubble retention rate to 2% or less; any method can be used. In other words, while Example 1 and the following Examples 2 to 6 reduce the bubble retention rate by embossing, embossing is not the only method that can reduce the bubble retention rate.

[0058] (Example 2) In Example 2, the laminated glass used PVB as the adhesive layer, with a thickness of 4 μm after lamination. The surface of the adhesive layer was embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 0%.

[0059] (Example 3) In Example 3, the laminated glass used PVB as the adhesive layer, with a thickness of 8 μm after lamination. The surface of the adhesive layer was embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 0%.

[0060] (Example 4) In Example 4, the laminated glass used PVB as the adhesive layer, with a thickness of 20 μm after lamination. The surface of the adhesive layer was embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction. The radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 0%.

[0061] (Example 5) In Example 5, the laminated glass used PVB as the adhesive layer, with a thickness of 25 μm after lamination. The surface of the adhesive layer was embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 0%.

[0062] (Example 6) In Example 6, the laminated glass used PVB as the adhesive layer, with a thickness of 30 μm after lamination. The surface of the adhesive layer was embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 0%.

[0063] (Example 7) In Example 7, the laminated glass used PVB as the adhesive layer, with a thickness of 25 μm after lamination. The surface of the adhesive layer was not embossed (uneven), the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 6%.

[0064] (Example 8) The laminated glass in Example 8 was prepared using a UV-curing resin as the adhesive layer, with a thickness of 2 μm after lamination. The adhesive layer surface was not embossed (uneven), the length of the laminated glass was 200 mm in the vertical direction, the length was 200 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the bubble retention rate was 5%. Specifically, the UV-curing resin used here was a mixture of 100 parts A-TMPT (Shin-Nakamura Chemical) and 5 parts Omnirad 184 (IGM·Resins·BV). The same applies to the UV-curing resins in subsequent examples.

[0065] (Example 9) In Example 9, a UV-curing resin was used as the adhesive layer, the thickness of the adhesive layer after lamination was set to 2 μm, no embossing (unevenness) was applied to the surface of the adhesive layer, the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 6%.

[0066] (Example 10) In Example 10, a UV-curing resin was used as the adhesive layer, the thickness of the adhesive layer after lamination was set to 20 μm, no embossing (unevenness) was applied to the surface of the adhesive layer, the length of the laminated glass was 1200 mm in the vertical direction and 1600 mm in the horizontal direction, the radius of curvature in the vertical direction was 20000 mm, the radius of curvature in the horizontal direction was 10000 mm, and the sample had a bubble retention rate of 6%.

[0067] (Example 11) In Example 11, a UV-curing resin was used as the adhesive layer, the thickness of the adhesive layer after lamination was set to 4 μm, and the surface of the adhesive layer was embossed (uneven). The length of the laminated glass was set to 1200 mm in the vertical direction and 1600 mm in the horizontal direction. The radius of curvature in the vertical direction was set to 20000 mm, the radius of curvature in the horizontal direction was set to 10000 mm, and the sample had a bubble retention rate of 6%.

[0068] (Evaluation results) Table 1 shows the conditions and evaluation results for Examples 1 to 11. Examples 1 to 5 are examples, and Examples 6 to 11 are comparative examples. As shown in Examples 1 to 5, it can be seen that by setting the thickness of the adhesive layer made of PVB to 2 μm or more and 25 μm or less, and reducing the bubble retention rate, the decrease in visibility and image clarity due to bubbles can be suppressed. When the thickness of the adhesive layer was less than 2 μm, the adhesive layer broke and proper molding could not be performed. Also, in Examples 8 to 10, the bubble retention rate was greater than 2%, so a decrease in visibility due to bubbles occurred. Furthermore, UV-curing resin is at a disadvantage compared to PVB in terms of impact resistance. Also, as shown in Example 11, when embossing was applied to the UV-curing resin, the adhesion of the adhesive layer to the glass deteriorated, and it was not possible to measure the image clarity.

[0069] [Table 1]

[0070] Examples 12 to 23 evaluated image clarity, bubble retention rate, and processability by varying the adhesive layer material, the thickness of the adhesive layer before lamination, the maximum height Rz of the adhesive layer before lamination (corresponding to the thickness D6a of the embodiment), and Rz / adhesive layer thickness (corresponding to the thickness ratio of the embodiment). In each example, 100 adhesive layers were molded, and laminated glass was created using one layer that did not tear during molding and had no pattern defects, in the same manner as in Examples 1 to 11. The evaluation of image clarity was the same as in Examples 1 to 11. For the bubble retention rate, the ratio of the area of ​​bubbles in a 100 mm square area where the most bubbles remained in the entire laminated glass was calculated as the bubble retention rate to the area of ​​that area. In the evaluation of the bubble retention rate, 0% or less was marked as a circle, 2% or less as a triangle, and greater than 2% as a cross, with circles and triangles being considered pass. Processability was evaluated using the presence or absence of fracture in the adhesive layer during molding and visual inspection of gaps in the adhesive layer pattern. If two or fewer fractures or gaps were found out of 100 samples, it was marked as "no fractures or gaps" (circle); if there were 3-4 fractures or gaps, it was marked as "triangle"; if there were 5 or more fractures or gaps, it was marked as "fractures and gaps" (cross); and a circle (circle) was considered a pass. Note that a gap in the pattern refers to a portion where the peaks of the uneven surface are fractured (for example, a portion with a thickness of 80% or less compared to an adjacent peak) when peeling the adhesive layer from the substrate B2, as shown in step S22 of Figure 6. In addition, as an optional evaluation, the tensile strength was evaluated for the PVB and EVA films alone as the adhesive layer material. The tensile strength was evaluated using JIS K7161, by preparing dumbbell-shaped test pieces with a gauge length (GL) of 50 mm from the PVB and EVA films and measuring them. Note that "―" in the evaluation result indicates that evaluation was not possible (including not evaluated).

[0071] (Example 12) In Example 12, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 6.2 μm, the maximum height Rz of the adhesive layer before lamination was set to 5 μm, and the Rz / adhesive layer thickness was set to 0.8.

[0072] (Example 13) In Example 13, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 6.6 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.82.

[0073] (Example 14) In Example 14, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 8.6 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.63.

[0074] (Example 15) In Example 15, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 9.8 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.55.

[0075] (Example 16) In Example 16, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 25 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.22.

[0076] (Example 17) In Example 17, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 30 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.18.

[0077] (Example 18) In Example 18, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 35 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.16.

[0078] (Example 19) In Example 19, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 5.7 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.95.

[0079] (Example 20) In Example 20, PVB was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 9.8 μm, the maximum height Rz of the adhesive layer before lamination was set to 4 μm, and the Rz / adhesive layer thickness was set to 0.41.

[0080] (Example 21) In Example 21, the laminated glass used EVA (Ethylene Vinyl Acetate Copolymer) as the adhesive layer, with a thickness of 6.2 μm for the adhesive layer before lamination, a maximum height Rz of 5 μm for the adhesive layer before lamination, and a ratio of Rz / adhesive layer thickness of 0.8.

[0081] (Example 22) In Example 22, EVA was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 6.6 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.82.

[0082] (Example 23) In Example 23, EVA was used as the adhesive layer for the laminated glass. The thickness of the adhesive layer before lamination was set to 35 μm, the maximum height Rz of the adhesive layer before lamination was set to 5.4 μm, and the Rz / adhesive layer thickness was set to 0.16.

[0083] (Evaluation results) Table 2 shows the conditions and evaluation results for Examples 12 to 23. Examples 12 to 17 are examples, and Examples 18 to 23 are comparative examples. As shown in Examples 12 to 17 and 19, it can be seen that the decrease in image clarity can be suppressed by making the thickness of the adhesive layer before lamination, which is made of PVB, 30 μm or less. Also, as shown in Examples 12 to 18, it was found that processability can be maintained by making the Rz / adhesive layer thickness less than 0.95. In Example 20, the bubble retention rate was greater than 2%. That is, as shown in Example 20, the bubble retention rate will fail if the Rz value is less than 5 μm. Note that in Example 20, image clarity could not be evaluated due to the appearance defect caused by bubbles. Also, as shown in Examples 21 to 23, it can be seen that if the adhesive layer is made of EVA, at least one of the processability and image clarity will fail. Regarding the evaluation of tensile strength, PVB film has a tensile strength of 329 MPa, while EVA film has a tensile strength of 190 MPa. Since EVA has a lower tensile strength, processability deteriorates. It is preferable that the adhesive layer has a tensile strength of 300 MPa or higher, like PVB.

[0084] [Table 2]

[0085] Although embodiments of the present invention have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above. [Explanation of Symbols]

[0086] 1. Laminated glass 12. First glass substrate 14. Second glass substrate 16 Reflective layer 18 Middle Class 20 PVB layers

Claims

1. A first glass substrate on the exterior side of the vehicle, The second glass substrate on the inside of the vehicle, A reflective layer provided between the first glass substrate and the second glass substrate, A PVB layer made of polyvinyl butyral resin is provided between the second glass substrate and the reflective layer, Laminated glass having, The aforementioned reflective layer is a P-polarized reflective film, The thickness of the PVB layer is 2 μm or more and 25 μm or less. The vertical radius of curvature of the laminated glass is 4,000 mm or more and 20,000 mm or less, and the horizontal radius of curvature of the laminated glass is 1,000 mm or more and 10,000 mm or less. The bubble retention rate in the aforementioned laminated glass is 2% or less. Laminated glass.

2. The first glass substrate and the reflective layer are further provided with an intermediate layer made of polyvinyl butyral resin, The laminated glass according to claim 1, wherein the intermediate layer is thicker than the PVB layer.

3. In a plan view of the laminated glass, it has a region in which the reflective layer is not formed, and in that region, the PVB layer and the intermediate layer are bonded together and form a single unit. The laminated glass according to claim 2.

4. The laminated glass according to any one of claims 1 to 3, wherein the thickness of the PVB layer is 4 μm or more and 25 μm or less.

5. The laminated glass according to claim 4, wherein the thickness of the PVB layer is 4 μm or more and 20 μm or less.

6. The laminated glass according to any one of claims 1 to 5, wherein the surface of the PVB layer has irregularities.

7. The laminated glass according to any one of claims 1 to 6, wherein the diameter of the bubbles in the laminated glass related to the bubble retention rate is 2 mm or less.

8. Laminated glass according to any one of claims 1 to 7, wherein the length in the vertical and horizontal directions is 200 mm or more.

9. The process involves applying a coating solution, which is a liquid to which polyvinyl butyral resin is added, to the surface of a substrate on which irregularities are formed on the surface, The steps include: drying the coating solution to remove the liquid component of the coating solution to form a PVB layer, which is a layer of polyvinyl butyral resin, having a thickness of 30 μm or less, a maximum surface height Rz of 5 μm or more on the substrate side, and a ratio of the maximum height Rz to the thickness of less than 0.95; A method for manufacturing a PVB layer, including the following.

10. The method for manufacturing a PVB layer according to claim 9, wherein in the step of forming the PVB layer, the PVB layer having a thickness of 25 μm or less is formed.

11. A method for manufacturing a PVB layer according to claim 9 or claim 10, wherein in the step of forming the PVB layer, the PVB layer having a maximum height Rz of 5.4 μm or more is formed.

12. A method for manufacturing a PVB layer according to any one of claims 9 to 11, wherein in the step of forming the PVB layer, the PVB layer having a ratio of 0.82 or less is formed.

13. A method for manufacturing laminated glass, comprising laminating a PVB layer manufactured by the method for manufacturing a PVB layer according to any one of claims 9 to 12, a reflective layer, a first glass substrate, and a second glass substrate.

14. The steps include: bonding the surface of the PVB layer opposite to the substrate to the reflective layer; The steps include removing the substrate from the PVB layer bonded to the reflective layer, The step of bonding the second glass substrate to the surface of the PVB layer opposite to the reflective layer, The steps include laminating the first glass substrate onto the surface of the reflective layer opposite to the PVB layer, A method for manufacturing laminated glass according to claim 13, including the method described in claim 13.

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