Laminate and image display device

Abstract

To provide a laminate capable of suppressing the amount of glass scattered when a glass member is crushed, and an image display device including the laminate.SOLUTION: The laminate 1D of the present invention includes a first plate-shaped member 2, a second plate-shaped member 4, and a thermoplastic resin sheet 3 including a thermoplastic resin disposed between the first plate-shaped member 2 and the second plate-shaped member 4, wherein the first plate-shaped member 2 is a glass member, the second plate-shaped member 4 is a glass member or an image display panel, in a plan view, the outer periphery 31 of the thermoplastic resin sheet 3 is at the same position as the outer periphery 21 of the first plate-like member 2 or extends outward with respect to the outer periphery 21 of the first plate-like member 2, and the outer periphery 31 of the thermoplastic resin sheet 3 is at the same position as the outer periphery 41 of the second plate-like member 4 or extends outward with respect to the outer periphery 41 of the second plate-like member 4. An image display device of the present invention includes the laminate of the present invention.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a laminate and an image display device including the laminate. [Background technology]

[0002] In recent years, there has been a trend toward larger display areas for in-vehicle displays. Display devices are provided with a front transparent plate (also called a "cover window") such as a transparent resin plate or glass plate to prevent damage to the image display panel due to impact from the outer surface. Conventionally, bonding materials such as acrylic pressure-sensitive adhesives, optically clear resins (OCR), and optically clear adhesives (OCA) have been used to bond the cover glass and the image display panel (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2020-533647 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as the area of ​​vehicle image display devices increases, there is an increased risk that the cover glass provided in the vehicle image display device will shatter and the glass will fly in the event of a vehicle collision, etc. However, conventional bonding members have been insufficient in suppressing the amount of glass that will fly in the event of a vehicle collision, etc.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a laminate capable of suppressing the amount of glass that scatters when a glass member is shattered, and an image display device including the laminate. [Means for solving the problem]

[0006] After extensive research, the inventors discovered that the above problem can be solved by adjusting the position of the outer periphery of the thermoplastic resin sheet relative to the position of the outer periphery of the plate-like member in the laminate, and completed the present invention as described below. That is, the present invention provides the following [1] to

[10] . [1] A thermoplastic resin sheet including a first plate-shaped member, a second plate-shaped member, and a thermoplastic resin sheet disposed between the first plate-shaped member and the second plate-shaped member, the first plate-like member is a glass member, the second plate-like member is a glass member or an image display panel, A laminate in which, in a planar view, the outer periphery of the thermoplastic resin sheet is at the same position as the outer periphery of the first plate-shaped member or extends outward relative to the outer periphery of the first plate-shaped member, and the outer periphery of the thermoplastic resin sheet is at the same position as the outer periphery of the second plate-shaped member or extends outward relative to the outer periphery of the second plate-shaped member. [2] The storage modulus of the thermoplastic resin sheet at 23°C (G'(23°C)) is 1 x 10 6 Pa or more 2×10 7 Pa or less, The storage modulus of the thermoplastic resin sheet at 100°C (G'(100°C)) is 1×10 4 Pa or more 3×10 5 The laminate according to the above [1], wherein the saturation temperature is 100°C or less. [3] The laminate according to [1] or [2] above, wherein the peel strength of the thermoplastic resin sheet to the first plate-like member is 10 N / 25 mm or more. [4] The laminate according to any one of the above [1] to [3], wherein the glass mass loss rate before and after the following collision test is 0.12% or less. (Crash test method) (1) The first plate-shaped member of the laminate is replaced with a glass plate having the same size as the first plate-shaped member and a thickness of 1.1 mm, so that the arrangement of the first plate-shaped member relative to the thermoplastic resin sheet is the same, and the second plate-shaped member of the laminate is replaced with a glass plate having the same size as the second plate-shaped member and a thickness of 1.1 mm, so that the arrangement of the second plate-shaped member relative to the thermoplastic resin sheet is the same, to prepare a test sample. (2) The initial mass of the test sample is measured. (3) The test sample is left in a thermostatic chamber set at 23°C until the temperature of the test sample reaches 23°C. (4) After placing the test sample horizontally with the first plate-shaped member on top, an iron ball with a mass of 110.69 g is dropped from a height of 9 m onto a position within a distance of 1 cm to 2 cm inward from the edge of the test sample. (5) Remove the glass plate that was peeled off by the falling iron ball. (6) After removing the glass plate that was peeled off by the falling iron ball, measure the mass of the test sample after the test. (7) The mass reduction rate (%) is calculated by subtracting the mass after the test from the initial mass and dividing the obtained value by the initial mass. [5] A laminate according to any one of the above [1] to [4], wherein the outer periphery of the thermoplastic resin sheet extends outward by a distance of 1 mm or more and 15 mm or less from the outer periphery of the plate-shaped member having a smaller projected area than the projected area of ​​the first plate-shaped member when projected in the thickness direction and the projected area of ​​the second plate-shaped member when projected in the thickness direction. [6] A laminate according to any one of [1] to [4] above, wherein, in a plan view, the outer periphery of the thermoplastic resin sheet extends outward from the outer periphery of the first plate-like member by a distance of 0 mm or more and 5 mm or less. [7] The laminate according to any one of the above [1] to [6], wherein the first plate-shaped member and the second plate-shaped member are made of inorganic glass. [8] The laminate according to any one of the above [1] to [7], wherein the thermoplastic resin is a polyvinyl acetal resin, an ethylene-vinyl acetate copolymer resin (EVA), a polyurethane resin (PU), or an ionomer resin. [9] A laminate according to any one of [1] to [8] above, wherein, in a plan view, the outer periphery of the first plate-like member, the outer periphery of the thermoplastic resin sheet, and the outer periphery of the second plate-like member are in the same position.

[10] An image display device comprising the laminate according to any one of the above [1] to [9]. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a laminate capable of suppressing the amount of glass that scatters when a glass member is shattered, and an image display device including the laminate. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1(a) is a plan view showing an example of the laminate of the present invention, and FIG. 1(b) is a cross-sectional view taken along the line AA of FIG. 1(a). [Figure 2] FIG. 2(a) is a plan view showing an example of the laminate of the present invention, and FIG. 2(b) is a cross-sectional view taken along the line AA of FIG. 2(a). [Figure 3] FIG. 3(a) is a plan view showing an example of the laminate of the present invention, and FIG. 3(b) is a cross-sectional view taken along the line AA of FIG. 3(a). [Figure 4] FIG. 4(a) is a plan view showing an example of the laminate of the present invention, and FIG. 4(b) is a cross-sectional view taken along the line AA of FIG. 4(a). [Figure 5] 5(a) to 5(c) are diagrams for explaining the method for measuring the peel strength. [Figure 6] FIG. 6 is a diagram for explaining the collision test. [Figure 7] FIG. 7(a) is a plan view showing a laminate of a comparative example, and FIG. 7(b) is a cross-sectional view taken along the line AA of FIG. 7(a). [Figure 8] FIG. 8(a) is a plan view showing a laminate of a comparative example, and FIG. 8(b) is a cross-sectional view taken along the line AA of FIG. 8(a). DETAILED DESCRIPTION OF THE INVENTION

[0009] [Laminate] The laminate of the present invention comprises a first plate-shaped member, a second plate-shaped member, and a thermoplastic resin sheet containing a thermoplastic resin disposed between the first plate-shaped member and the second plate-shaped member. The first plate-shaped member is a glass member, and the second plate-shaped member is a glass member or an image display panel. Furthermore, in a plan view, the periphery of the thermoplastic resin sheet is located at the same position as the periphery of the first plate-shaped member or extends outward from the periphery of the first plate-shaped member, and the periphery of the thermoplastic resin sheet is located at the same position as the periphery of the second plate-shaped member or extends outward from the periphery of the second plate-shaped member. This reduces the amount of glass that scatters when the glass member is shattered.

[0010] (Outer periphery) In the laminate of the present invention, in a plan view, the outer periphery of the thermoplastic resin sheet is either coaxial with the outer periphery of the first plate-like member or extends outward relative to the outer periphery of the first plate-like member, and the outer periphery of the thermoplastic resin sheet is either coaxial with the outer periphery of the second plate-like member or extends outward relative to the outer periphery of the second plate-like member. For example, as in laminate 1A shown in FIG. 1, the outer periphery 31 of thermoplastic resin sheet 3 may be coaxial with the outer periphery 21 of first plate-like member 2 and the outer periphery 41 of second plate-like member 4. As in laminate 1B shown in FIG. 2, the outer periphery 31 of thermoplastic resin sheet 3 may be coaxial with the outer periphery 21 of first plate-like member 2 and extend outward relative to the outer periphery 41 of second plate-like member 4. As in laminate 1C shown in FIG. 3, the outer periphery 31 of thermoplastic resin sheet 3 may be coaxial with the outer periphery 21 of first plate-like member 2 and extend outward relative to the outer periphery 41 of second plate-like member 4. Furthermore, as in the laminate 1D shown in Figure 4, the outer periphery 31 of the thermoplastic resin sheet 3 may extend outward relative to the outer periphery 21 of the first plate-like member 2 and may also extend outward relative to the outer periphery 41 of the second plate-like member 4. In this context, the term "same position" means that the outer periphery of the thermoplastic resin sheet is in exactly the same position as the outer periphery of the plate-like member, or that any misalignment is within 1 mm, and the amount of misalignment is preferably less than 0.5 mm, more preferably less than 0.1 mm.

[0011] Conventional optically transparent adhesives (OCA) have strong tackiness, so when conventional OCA is used to bond the first and second plate-shaped members, there is a high possibility of foreign matter being trapped. Therefore, the periphery of the first plate-shaped member and the periphery of the second plate-shaped member extend outward relative to the periphery of the OCA. Furthermore, conventional optically transparent resins (OCR) are liquid, so when conventional OCR is used, banks must be formed to prevent the OCR from leaking from the sides of the laminate. These banks are usually formed on the periphery of the first plate-shaped member and the periphery of the second plate-shaped member. As a result, the periphery of the first plate-shaped member and the periphery of the second plate-shaped member extend outward relative to the periphery of the OCR. Therefore, when conventional OCA or OCR is used, there are portions of the periphery of the first plate-shaped member and the periphery of the second plate-shaped member that are not bonded to the bonding member, and it has been found that the amount of glass that scatters when the glass members are shattered cannot be sufficiently suppressed. In contrast, in the present invention, by adopting any of the above-mentioned embodiments, the amount of glass that scatters when the glass member is shattered can be reduced. If the glass member extends, the glass member is more likely to break, increasing the amount of glass that scatters when the glass member is shattered. With the laminate of the present invention, even when the thermoplastic resin sheet is bonded at the exact edge, there is no side tack, and the amount of glass that scatters when the glass member is shattered can be reduced.

[0012] Among the above-mentioned embodiments, it is preferable that the outer periphery of the thermoplastic resin sheet is located at the same position as the outer periphery of the first plate-like member and the outer periphery of the second plate-like member. By adopting this embodiment, the handling of the laminate is improved and contamination during the formation of the laminate can be suppressed. Specifically, when nipper rolls are used to laminate the plate-like member and the thermoplastic resin, contamination of the nipper rolls can be suppressed.

[0013] Furthermore, in the present invention, when the periphery of the thermoplastic resin sheet extends beyond at least one of the periphery of the first plate-shaped member and the periphery of the second plate-shaped member, the following embodiment is preferred. That is, the periphery of the thermoplastic resin sheet preferably extends outward from the periphery of the plate-shaped member having the smaller projected area of ​​the first plate-shaped member when projected in the thickness direction and the second plate-shaped member when projected in the thickness direction by a distance of 1 mm to 15 mm. When the distance by which the periphery of the thermoplastic resin sheet extends outward from the periphery of the plate-shaped member having the smaller projected area of ​​the first plate-shaped member and the second plate-shaped member is 1 mm or more, the amount of glass scattered when the glass member is crushed is more easily reduced. From this perspective, the distance by which the periphery of the thermoplastic resin sheet extends outward from the periphery of the plate-shaped member having the smaller projected area of ​​the first plate-shaped member and the second plate-shaped member is more preferably 1.5 mm or more, and even more preferably 2.5 mm or more. Furthermore, by setting the distance by which the outer periphery of the thermoplastic resin sheet extends outward from the periphery of the plate-shaped member with the smaller projected area of ​​the first plate-shaped member and the second plate-shaped member to 15 mm or less, the amount of glass scattered when the glass member is crushed can be effectively reduced, while also reducing contamination during the formation of the laminate, such as contamination of the nipper roll as described above. From this perspective, it is preferable that the distance by which the outer periphery of the thermoplastic resin sheet extends outward from the periphery of the plate-shaped member with the smaller projected area of ​​the first plate-shaped member and the second plate-shaped member be 15 mm or less. The distance by which the outer periphery of the thermoplastic resin sheet extends outward from the periphery of the first plate-shaped member is, for example, t1 as shown in FIGS. 3 and 4, and the distance by which the outer periphery of the thermoplastic resin sheet extends outward from the periphery of the second plate-shaped member is, for example, t2 as shown in FIGS. 2 and 4. The thickness direction is the z-direction in FIGS. 1 to 4. If the extension distance is not constant throughout the entire periphery, it is taken as an average value. Furthermore, when the projected area of ​​the first plate-shaped member and the projected area of ​​the second plate-shaped member are the same, the distance by which the outer periphery of either one of the plate-shaped members extends outward may be within the above range.

[0014] Furthermore, in a plan view, it is preferable that the outer periphery of the thermoplastic resin sheet extends outward from the outer periphery of the first plate-shaped member by a distance of 0 mm to 5 mm. When the distance by which the outer periphery of the thermoplastic resin sheet extends outward from the outer periphery of the first plate-shaped member is 0 mm or more, the amount of glass that scatters when the glass member is shattered can be further reduced. When the distance by which the outer periphery of the thermoplastic resin sheet extends outward from the outer periphery of the first plate-shaped member is 5 mm or less, the laminate can be easily fitted into a housing that is sized to fit, for example, a cover glass formed by the first plate-shaped member. From this perspective, the distance by which the outer periphery of the thermoplastic resin sheet extends outward from the outer periphery of the first plate-shaped member is more preferably 0 mm to 4 mm, and even more preferably 0 mm to 3 mm. The first plate-like member is preferably disposed on the outermost surface of various devices, such as an image display device, to which the laminate is applied, and serves as a member constituting a cover glass, etc. In other words, the surface of the first plate-like member is preferably the surface on the side of the laminate that receives an impact.

[0015] (Storage modulus at 23°C) The storage modulus (G'(23°C)) of the thermoplastic resin sheet at 23°C is preferably 1 x 10 6 Pa or more 2×10 7 The storage modulus of the thermoplastic resin sheet at 23°C (G'(23°C)) is 1 x 10 6 When the storage modulus (G'(23°C)) of the thermoplastic resin sheet at 23°C is 2×10 Pa or more, the tackiness of the thermoplastic resin sheet at room temperature is suppressed, and as described above, even if the outer periphery of the thermoplastic resin sheet is in the same position as the outer periphery of the plate-like member or extends outward, it is possible to prevent the thermoplastic resin sheet from adhering to other members or foreign matter from adhering thereto. 7 When the storage modulus at 23°C (G'(23°C)) of the thermoplastic resin sheet is 1.25 × 10 Pa or less, the flexibility of the thermoplastic resin sheet can be increased. From this viewpoint, the storage modulus at 23°C (G'(23°C)) of the thermoplastic resin sheet is more preferably 1.25 × 10 6 Pa or more 1.85×10 7Pa or less, and more preferably 1.5 × 10 6 Pa or more 1.6×10 7 The storage modulus at 23°C (G'(23°C)) of the thermoplastic resin sheet can be measured by the method described in the Examples below. The storage modulus at 23°C (G'(23°C)) of the thermoplastic resin sheet can be adjusted by the type of resin constituting the thermoplastic resin sheet, the content of plasticizer, etc.

[0016] (Storage modulus at 100°C) The storage modulus of the thermoplastic resin sheet at 100°C (G'(100°C)) is preferably 1 x 10 4 Pa or more 3×10 5 The storage modulus of the thermoplastic resin sheet at 100°C (G'(100°C)) is 1 x 10 4 When the storage modulus (G'(100°C)) of the thermoplastic resin sheet at 100°C is 3 x 10 Pa or more, the thermoplastic resin sheet has a certain mechanical strength, and therefore it is easy to convey the sheet while applying tension, which makes it easy to mold the thermoplastic resin sheet by extrusion molding, for example, and improves film formability. 5 When the storage modulus G'(100°C) of the thermoplastic resin sheet at 100°C is 1.25 × 10 Pa or less, the thermoplastic resin sheet can be bonded to the plate-like member with an appropriate adhesive force by heating. From this viewpoint, the storage modulus G'(100°C) of the thermoplastic resin sheet at 100°C is more preferably 1.25 × 10 4 Pa or more 2.9×10 5 Pa or less, and more preferably 1.5 × 10 4 Pa or more 2.8×10 5 The storage modulus at 100°C (G'(100°C)) of the thermoplastic resin sheet can be measured by the method described in the Examples below. The storage modulus at 100°C (G'(100°C)) of the thermoplastic resin sheet can be adjusted by the type of resin constituting the thermoplastic resin sheet, the content of plasticizer, etc.

[0017] (peel strength) In the present invention, the peel strength of the thermoplastic resin sheet from the first plate-like member is preferably 10 N / 25 mm or more. When the peel strength of the thermoplastic resin sheet from the first plate-like member is 10 N / 25 mm or more, the glass member can be bonded to the thermoplastic resin sheet with an appropriate adhesive force, and the amount of glass that scatters when the glass member is shattered can be easily reduced. From this perspective, the peel strength of the thermoplastic resin sheet from the first plate-like member is more preferably 45 N / 25 mm or more, and even more preferably 75 N / 25 mm or more. The upper limit of the range of the peel strength of the thermoplastic resin sheet from the first plate-like member is not particularly limited, and a higher value is preferable, but it is, for example, 200 N / 25 mm or less, 150 N / 25 mm or less. The peel strength of the thermoplastic resin sheet from the first plate-like member can be measured by the method described in the Examples below. The peel strength of the thermoplastic resin sheet from the first plate-like member can be adjusted by the type of resin constituting the thermoplastic resin sheet, the content of plasticizer, etc.

[0018] (Glass mass reduction rate) In the laminate of the present invention, the glass mass loss rate before and after the following collision test is preferably 0.12% or less. If the glass mass loss rate is 0.12% or less, the amount of glass that scatters when the glass member is shattered can be further reduced. From this perspective, the glass mass loss rate is more preferably 0.10% or less, and even more preferably 0.09% or less. The lower limit of the range of the glass mass loss rate is, for example, 0.00%. The glass mass loss rate can be adjusted by the positional relationship between the periphery of the thermoplastic resin sheet and the periphery of the first plate-like member, the positional relationship between the periphery of the thermoplastic resin sheet and the periphery of the second plate-like member, the type of resin constituting the thermoplastic resin sheet, the content of plasticizer, etc.

[0019] <Crash test method> (1) A test sample is prepared by replacing the first plate-like member of the laminate with a glass plate of the same size and thickness as the first plate-like member, so that the arrangement of the first plate-like member relative to the thermoplastic resin sheet is the same, and replacing the second plate-like member of the laminate with a glass plate of the same size and thickness as the second plate-like member, so that the arrangement of the second plate-like member relative to the thermoplastic resin sheet is the same. In this case, the preparation conditions for the test sample may be as described in the Examples. (2) Measure the initial mass of the test sample. (3) The test sample is left in a thermostatic chamber set at 23°C until the temperature of the test sample reaches 23°C. (4) After placing the test sample horizontally with the first plate-shaped member on top, an iron ball with a mass of 110.69 g is dropped from a height of 9 m onto a position within a distance of 1 cm to 2 cm inward from the edge of the test sample. (5) Remove the glass plate that was torn off by the falling iron ball. (6) After removing the glass plate that was peeled off by the falling iron ball, measure the mass of the test sample after the test. (7) Subtract the mass after the test from the initial mass and divide the obtained value by the initial mass to calculate the mass reduction rate (%).

[0020] (thermoplastic resin sheet) The thermoplastic resin sheet contains a thermoplastic resin. Unlike conventional OCR, the thermoplastic resin sheet does not require a leak-preventing bank and softens upon heating, allowing it to bond a first plate-shaped member and a second plate-shaped member. Meanwhile, the adhesiveness of the thermoplastic resin sheet at room temperature is suppressed. Therefore, even when the periphery of the thermoplastic resin sheet is aligned with the periphery of the first plate-shaped member or extends outward relative to the periphery of the first plate-shaped member, and the periphery of the thermoplastic resin sheet is aligned with the periphery of the second plate-shaped member or extends outward relative to the periphery of the second plate-shaped member, the inclusion of foreign matter can be suppressed. In other words, the laminate of the present invention overcomes the problems of the need for a leak-preventing bank and the inclusion of foreign matter encountered with conventional bonding members, while simultaneously achieving a configuration in which no portions of the peripheries of the first and second plate-shaped members are not bonded to the bonding members. As a result, the amount of glass scattered when the glass member is shattered can be reduced. Examples of thermoplastic resins contained in the thermoplastic resin sheet include (meth)acrylic resins, polyvinyl acetal resins, polyvinyl alcohol resins (PVA), polyurethane resins (PU), ethylene-vinyl acetate copolymer resins (EVA), saponified ethylene-vinyl acetate copolymers (EVOH), ethylene-methacrylic acid copolymer resins, ionomer resins, isobutylene resins, styrene-isoprene copolymer resins, and styrene-butadiene copolymer resins. These thermoplastic resins may be used alone or in combination. Among these thermoplastic resins, polyvinyl acetal resins, ethylene-vinyl acetate copolymer resins (EVA), polyurethane resins (PU), and ionomer resins are preferred, with polyvinyl acetal resins being more preferred, and polyvinyl butyral resins being even more preferred, from the viewpoints of suppressing adhesion at room temperature to prevent foreign matter from adhering to the thermoplastic resin sheet and increasing adhesion strength at elevated temperatures to enable the thermoplastic resin sheet to be properly bonded to a plate-like member.

[0021] (Polyvinyl acetal resin) The polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet may be a modified polyvinyl acetal resin or an unmodified polyvinyl acetal resin. As described below, the modified polyvinyl acetal resin may have a structure (modifying group) other than an acetal group, a hydroxyl group, and an acetyl group, and preferably has the modifying group in a side chain. Polyvinyl acetal resins can be obtained by acetalizing polyvinyl alcohol with an aldehyde, and then, if necessary, reacting the polyvinyl alcohol with a modifier or subjecting the polyvinyl alcohol to a reacetylation treatment. Modified polyvinyl alcohol may also be used as the raw material for obtaining modified polyvinyl acetal resins.

[0022] <Degree of acetalization> The degree of acetalization of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably 65 mol% or more and 75 mol% or less. When the degree of acetalization of the polyvinyl acetal resin is 65 mol% or more, the polyvinyl acetal resin has fewer hydroxyl groups, and the polyvinyl acetal resin has sufficient flexibility. This further reduces the amount of glass that scatters when the glass member is crushed. Furthermore, when the degree of acetalization of the polyvinyl acetal resin is 75 mol% or less, the adhesion to transparent substrates such as glass is improved. From this perspective, the degree of acetalization of the polyvinyl acetal resin is more preferably 67 mol or more and 74 mol or less, even more preferably 68 mol or more and 73 mol or less, and even more preferably 69 mol or more and 72 mol or less. The degree of acetalization means the degree of butyralization when the acetal group is a butyral group and the polyvinyl acetal resin is a polyvinyl butyral resin.

[0023] The degree of acetalization is a molar fraction calculated by subtracting the amount of ethylene groups having hydroxyl groups bonded thereto and the amount of ethylene groups having acetyl groups bonded thereto from the total amount of ethylene groups in the main chain, and dividing the result by the total amount of ethylene groups in the main chain. The degree of acetalization (degree of butyralization) may be calculated based on the amount of ethylene groups having hydroxyl groups bonded thereto and the amount of ethylene groups having acetyl groups bonded thereto, which are calculated by the procedures described in the Examples below.

[0024] <Weight average molecular weight> The weight-average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably 220,000 or more. When the weight-average molecular weight (Mw) of the polyvinyl acetal resin is 220,000 or more, the impact resistance of the polyvinyl acetal resin can be improved. From this perspective, the weight-average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is more preferably 230,000 or more, and even more preferably 240,000 or more. Furthermore, the weight-average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably 310,000 or less. When the weight-average molecular weight (Mw) of the polyvinyl acetal resin is 310,000 or less, the thermoplastic resin sheet has sufficient flexibility, which can further reduce the amount of glass that scatters when the glass member is crushed. From this viewpoint, the weight average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is more preferably 305,000 or less, and even more preferably 300,000 or less. The weight average molecular weight (Mw) of the polyvinyl acetal resin is measured by gel permeation chromatography.

[0025] <Aldehyde> The polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably a polyvinyl acetal resin obtained by acetalizing polyvinyl alcohol (PVA) with an aldehyde. The aldehyde is not particularly limited, but generally, an aldehyde having 1 to 10 carbon atoms is suitably used. The aldehyde having 1 to 10 carbon atoms is not particularly limited, and examples thereof include n-butylaldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, formaldehyde, acetaldehyde, benzaldehyde, etc. These aldehydes may be used alone or in combination of two or more. Among the above, n-butylaldehyde, n-hexylaldehyde, and n-valeraldehyde are preferred, and n-butylaldehyde is more preferred. Therefore, the polyvinyl acetal resin is preferably a polyvinyl butyral resin.

[0026] <Polyvinyl alcohol (PVA)> Polyvinyl alcohol (PVA) can be obtained by saponifying a polyvinyl ester such as polyvinyl acetate, etc. The degree of saponification of polyvinyl alcohol is generally 70 to 99.9 mol %. The average degree of polymerization of the PVA is preferably 200 or more, more preferably 500 or more, even more preferably 1000 or more, and even more preferably 1500 or more. When the average degree of polymerization is equal to or greater than the above-mentioned lower limit, the impact resistance of the polyvinyl acetal resin can be improved. Furthermore, the average degree of polymerization of the PVA is preferably 5000 or less, more preferably 4000 or less, even more preferably 3500 or less, and even more preferably 2500 or less. When the average degree of polymerization is equal to or less than the above-mentioned upper limit, the thermoplastic resin sheet has sufficient flexibility, and as a result, the amount of glass that scatters when the glass member is crushed can be further reduced. The average degree of polymerization of polyvinyl alcohol is determined by a method conforming to JIS K6726 "Testing Method for Polyvinyl Alcohol." When two or more types of polyvinyl alcohol are used as raw materials, the average degree of polymerization of the polyvinyl alcohol can be estimated by calculation from the average degrees of polymerization of each polyvinyl alcohol.

[0027] Two or more polyvinyl alcohols having different average degrees of polymerization may be used as the polyvinyl alcohol raw material for the polyvinyl acetal resin. In this case, it is preferable to use a mixture of two or more polyvinyl alcohols as the raw material to produce the polyvinyl acetal resin by the production method described below.

[0028] <Amount of hydroxyl groups> The hydroxyl group content of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably 15 mol% or more, and preferably 38 mol% or less. By setting the hydroxyl group content to 15 mol% or more, good adhesion to plate-like members is likely to be achieved. Furthermore, by setting the hydroxyl group content to 38 mol% or less, flexibility is easily ensured, and the amount of glass scattered when the glass member is crushed can be further reduced. The amount of hydroxyl groups is more preferably 20 mol % or more, and even more preferably 25 mol % or more, and more preferably 35 mol % or less, and even more preferably 33 mol % or less. When a polyvinyl butyral resin is used as the polyvinyl acetal resin, from the same viewpoint, the amount of hydroxyl groups is 15 mol% or more, and preferably 38 mol% or less, more preferably 20 mol% or more, even more preferably 25 mol% or more, more preferably 35 mol% or less, and even more preferably 33 mol% or less. The amount of hydroxyl groups in the polyvinyl acetal resin is a molar fraction calculated by dividing the amount of ethylene groups to which hydroxyl groups are bonded by the total amount of ethylene groups in the main chain, and is expressed as a percentage. The amount of ethylene groups to which the hydroxyl groups are bonded can be measured by the procedure described in the Examples below.

[0029] <Degree of acetylation> The acetylation degree of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, and even more preferably 2 mol% or less. When the acetylation degree is below the upper limit, the moisture resistance of the thermoplastic resin sheet is increased. Furthermore, the acetylation degree is not particularly limited, but is preferably 0.01 mol% or more, more preferably 0.1 mol% or more. The degree of acetylation is a molar fraction calculated by dividing the amount of ethylene groups having acetyl groups bonded thereto by the total amount of ethylene groups in the main chain, and is expressed as a percentage. The amount of ethylene groups having acetyl groups bonded thereto can be measured by the procedure described in the Examples below.

[0030] <Modified polyvinyl acetal resin> The polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin sheet is preferably an unmodified polyvinyl acetal resin, but may also be a modified polyvinyl acetal resin. The modified polyvinyl acetal resin has a structure (modifying group) other than an acetal group, a hydroxyl group, and an acetyl group, and preferably has a modifying group on a side chain. Examples of the modifying group include those having a polyalkylene oxide structure on a side chain, and those having an alkyl group (e.g., having about 2 to 30 carbon atoms) other than an acetal group or an acetyl group on a side chain. A preferred modified polyvinyl acetal resin is a polyalkylene oxide-modified polyvinyl acetal resin, and a more preferred modified polyvinyl acetal resin is a polyethylene oxide-modified polyvinyl acetal resin. The modification amount is not particularly limited, but is, for example, about 0.1 mol % to 10 mol %. The modification amount represents the ratio of functional groups to all vinyl monomer units constituting the polyvinyl acetal resin.

[0031] (Method for producing polyvinyl acetal resin) The polyvinyl acetal resin is preferably produced by a production method including a mixing step of mixing the polyvinyl alcohol and the aldehyde, and an aging step of aging the mixture obtained in the mixing step.

[0032] In the mixing step, polyvinyl alcohol and aldehyde may be mixed according to a conventional method. In addition to polyvinyl alcohol and aldehyde, a catalyst such as an acid catalyst may be added to promote the acetalization reaction. For example, the aldehyde may be added to a mixture of polyvinyl alcohol and an acid catalyst at a low temperature of about 0 to 40°C. A solvent such as water is also typically added. When two or more types of polyvinyl alcohols are used in combination (for example, when two or more types of polyvinyl alcohols with different molecular weights are used), it is advisable to mix the two or more types of polyvinyl alcohols with an aldehyde.

[0033] The aging step is not particularly limited, but may be carried out, for example, by adding a catalyst such as an acid catalyst to the mixture (reaction mixture) obtained by the mixing step, heating the mixture to a aging temperature, and maintaining the mixture at the aging temperature for a certain period of time. In this production method, acetalization of polyvinyl alcohol proceeds in the mixing step and the aging step, thereby producing a polyvinyl acetal resin. The reaction mixture is maintained at the aging temperature for a certain period of time, and then cooled appropriately and neutralized, and may then be washed with water, dried, or the like, as necessary.

[0034] Examples of the acid catalyst added in the mixing step and the aging step include inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, etc. In the aging step, the concentration of the acid catalyst may be adjusted to, for example, about 0.5% by mass or more and 5% by mass or less, and preferably about 1% by mass or more and 2.5% by mass or less.

[0035] The aging temperature in the aging step may be relatively low, for example, 30° C. to 68° C., preferably 30° C. to 65° C., more preferably 35° C. to 60° C., and even more preferably 40° C. to 58° C. The time for which the aging temperature is maintained (aging time) may be longer than a certain period of time, for example, 75 minutes to 180 minutes, preferably 90 minutes to 150 minutes, and more preferably 100 minutes to 140° C. Setting the aging temperature and aging time within the above-mentioned desired ranges is believed to facilitate uniform distribution of hydroxyl groups within the molecule of the polyvinyl acetal resin, resulting in a soft polyvinyl acetal resin that helps to reduce the amount of glass shattered when the glass member is crushed. Furthermore, the storage modulus at 100°C (G'(100°C)) and other properties are reduced, which facilitates increasing the adhesive strength to plate-like members. However, the aging temperature and aging time of the polyvinyl acetal resin used in the present invention do not necessarily have to be within the above ranges.

[0036] (plasticizer) The thermoplastic resin sheet preferably contains a plasticizer in addition to the thermoplastic resin, which makes the thermoplastic resin sheet more flexible and further reduces the amount of glass that scatters when the glass member is crushed.

[0037] Examples of the plasticizer include organic ester plasticizers, organic phosphorus-based plasticizers such as organic phosphate ester plasticizers and organic phosphite ester plasticizers, organic ether-based plasticizers such as polyalkylene glycol-based plasticizers and polyoxyalkylene ether-based plasticizers, and alcohol-based plasticizers. The plasticizers may be used alone or in combination of two or more. Among the above, organic ester plasticizers and organic ether plasticizers are preferred.

[0038] Preferred organic ester plasticizers include monobasic organic acid esters and polybasic organic acid esters. Examples of monobasic organic acid esters include esters of glycols and monobasic organic acids. Examples of glycols include polyalkylene glycols in which each alkylene unit has 2 to 4 carbon atoms, preferably 2 or 3 carbon atoms, and the number of repeating alkylene units is 2 to 10, preferably 2 to 4. The glycol may also be a monoalkylene glycol having 2 to 4 carbon atoms, preferably 2 or 3 carbon atoms (i.e., one repeating unit). Specific examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, and butylene glycol. Examples of monobasic organic acids include organic acids having 3 to 10 carbon atoms, and specific examples thereof include butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptyl acid, n-octylic acid, 2-ethylhexyl acid, n-nonylic acid, and decylic acid.

[0039] Specific monobasic organic acids include triethylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylhexanoate, triethylene glycol dicaprylate, triethylene glycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, tetraethylene glycol di-2-ethylhexanoate, diethylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, and triethylene glycol. Di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate, diethylene glycol dicaprylate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, triethylene glycol di-2-ethylbutyrate, ethylene glycol di-2-ethylbutyrate, 1,2-propylene glycol di-2-ethylbutyrate, 1,3-propylene glycol di-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate, 1,2-butylene glycol di-2-ethylbutyrate, and the like.

[0040] Furthermore, examples of polybasic organic acid esters include ester compounds of dibasic organic acids having 4 to 12 carbon atoms, such as adipic acid, sebacic acid, and azelaic acid, with alcohols having 4 to 10 carbon atoms. The alcohols having 4 to 10 carbon atoms may be linear, have a branched structure, or have a cyclic structure. Specific examples include dibutyl sebacate, dioctyl azelaate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, dibutyl carbitol adipate, and mixed adipates. Oil-modified alkyd sebacate is also acceptable. Examples of mixed adipates include adipates prepared from two or more alcohols selected from alkyl alcohols having 4 to 9 carbon atoms and cyclic alcohols having 4 to 9 carbon atoms.

[0041] The organic ester plasticizer is not limited to the complete esters of the above-mentioned esters, but may also be a partial ester. For example, it may be a partial ester of glycol and a monobasic organic acid, or a partial ester of a dibasic organic acid and an alcohol. Specific examples include triethylene glycol-mono-2-ethylhexanoate. Furthermore, it may be a partial ester of a monobasic organic acid with a trihydric or higher alcohol such as glycerin. Examples of the monobasic organic acid include monobasic organic acids having 3 to 24 carbon atoms, preferably 6 to 18 carbon atoms. Specific examples of the partial ester of a trihydric or higher alcohol with a monobasic organic acid include a mono- or diester of glycerin and stearic acid, and a mono- or diester of glycerin and 2-ethylhexyl acid. Of the organic ester plasticizers mentioned above, triethylene glycol-di-2-ethylhexanoate (3GO) is particularly preferably used.

[0042] Examples of the organic phosphorus plasticizer include phosphoric acid esters such as tributoxyethyl phosphate, isodecylphenyl phosphate, and triisopropyl phosphate. Examples of polyalkylene glycol plasticizers include polyethylene glycol, polypropylene glycol (PPG), poly(ethylene oxide / propylene oxide) block copolymers, poly(ethylene oxide / propylene oxide) random copolymers, and polytetramethylene glycol, and among these, polypropylene glycol is preferred.

[0043] The polyoxyalkylene ether plasticizer is an ether compound of a monohydric or polyhydric alcohol and a polyoxyalkylene. Specific examples of polyoxyalkylene ether plasticizers include polyoxyethylene hexyl ether, polyoxyethylene heptyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene allyl ether, polyoxypropylene allyl ether, polyoxyethylene glyceryl ether, polyoxypropylene glyceryl ether, polyoxyethylene diglyceryl ether, polyoxypropylene diglyceryl ether (DGP), and polyoxyalkylene pentaerythritol ether. The polyoxyalkylene ether plasticizer is preferably an ether compound of a polyhydric alcohol and a polyoxyalkylene, more preferably an ether compound of glycerin or diglycerin and a polyoxyalkylene, and even more preferably an ether compound of glycerin or diglycerin and a polyoxypropylene. Examples of alcohol-based plasticizers include various polyhydric alcohols such as butanediol, hexanediol, trimethylolpropane, pentaerythritol, etc. Among these, trimethylolpropane is preferred.

[0044] The above plasticizers can be used alone or in combination of two or more. Among the above plasticizers, triethylene glycol-di-2-ethylhexanoate (3GO), polyoxypropylene diglyceryl ether (DGP) and polypropylene glycol (PPG) are preferred, and triethylene glycol-di-2-ethylhexanoate (3GO) is more preferred.

[0045] The content of the plasticizer in the thermoplastic resin sheet is not particularly limited, but is preferably 10 parts by mass or more and 100 parts by mass or less relative to 100 parts by mass of the polyvinyl acetal resin. When the content of the plasticizer is 10 parts by mass or more, the thermoplastic resin sheet becomes appropriately flexible, and the amount of glass that scatters when the glass member is crushed can be further reduced. On the other hand, if the content of the plasticizer is 100 parts by mass or less, separation of the plasticizer from the thermoplastic resin sheet is prevented. The above content of plasticizer is more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and more preferably 70 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less.

[0046] The thermoplastic resin sheet may preferably be mainly composed of a thermoplastic resin, or a thermoplastic resin and a plasticizer, and the total amount of the thermoplastic resin and the plasticizer in the thermoplastic resin sheet is usually 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more but less than 100% by mass, based on the total amount of the thermoplastic resin sheet.

[0047] (additives) The thermoplastic resin sheet may further contain additives such as an adhesion modifier, a moisture resistance improver, a light stabilizer, an antioxidant, an ultraviolet absorber, an infrared absorber, a pigment, a dye, a fluorescent brightener, a crystal nucleating agent, an antistatic agent, an antiblocking agent, a refractive index modifier, and a light scattering agent in addition to the thermoplastic resin or a thermoplastic resin and a plasticizer.

[0048] (Method of manufacturing thermoplastic resin sheet) The thermoplastic resin sheet of the present invention may be obtained, for example, by mixing a resin and, if necessary, a plasticizer and various other additives, and molding the resulting resin composition by extrusion molding, press molding, or the like.

[0049] The thermoplastic resin sheet of the present invention may be a sheet having a single layer structure or a sheet having a multilayer structure. The single-layer sheet may be made of the thermoplastic resin described above, or may be made of a resin composition containing, in addition to the thermoplastic resin, additives such as a plasticizer, an adhesion modifier, a moisture resistance improver, a light stabilizer, and an antioxidant, as necessary. The content of each additive in the resin composition for the single-layer structure may be adjusted as described above. Furthermore, when the thermoplastic resin sheet has a multilayer structure, each layer may be made of a thermoplastic resin as described above, or may be made of a resin composition containing, in addition to the thermoplastic resin, additives such as a plasticizer, an adhesion modifier, a moisture resistance improver, a light stabilizer, an antioxidant, etc. In the case of a multilayer structure, the thermoplastic resin sheet may be made of a resin composition constituting each layer, as long as the content of each component is as described above. When the thermoplastic resin sheet has a multilayer structure, it can be obtained by forming each layer by extrusion molding, press molding, or the like, and then laminating them. For example, a method of co-extrusion using two or more extruders and attaching multilayer feed blocks to the tips of the extruders is preferred. Furthermore, when multiple layers are provided and two or more layers have the same composition, two or more layers having the same composition may be extruded from a single extruder.

[0050] The thickness of the thermoplastic resin sheet of the present invention is not particularly limited, but is, for example, 100 μm to 2000 μm, preferably 200 μm to 1300 μm, and more preferably 250 μm to 1000 μm. When the thickness of the thermoplastic resin sheet is equal to or greater than the above-mentioned lower limit, the amount of glass that scatters when the glass member is crushed can be reduced, and adhesion between the first plate-like member and the second plate-like member can be easily ensured. On the other hand, when the thickness is equal to or less than the above-mentioned upper limit, the light transmittance of the thermoplastic resin sheet is improved.

[0051] (First plate-shaped member) The first plate-like member is a glass member. The glass member is not particularly limited. Examples of the glass member include organic glass and inorganic glass. Examples of organic glass include (meth)acrylic plates such as polycarbonate plates and polymethyl methacrylate plates, polyester plates such as acrylonitrile-styrene copolymer plates, acrylonitrile-butadiene-styrene copolymer plates, and polyethylene terephthalate plates, fluorine-based resin plates, polyvinyl chloride plates, chlorinated polyvinyl chloride plates, polypropylene plates, polystyrene plates, polysulfone plates, epoxy resin plates, phenolic resin plates, unsaturated polyester resin plates, and polyimide resin plates. Examples of inorganic glass include float glass plates, tempered glass, colored glass, polished glass plates, figured glass plates, wired glass plates, lined glass plates, ultraviolet-absorbing glass plates, infrared-reflecting glass plates, infrared-absorbing glass plates, and green glass. Among these, inorganic glass is preferred, and float glass plates are more preferred. By using inorganic glass, the thermoplastic resin sheet can appropriately prevent glass from scattering when the glass member is shattered.

[0052] Float glass is a type of glass produced by the float process. Float glass is produced by pouring molten glass base onto molten tin, which has a higher specific gravity than glass, and cooling the molten glass while floating on the molten tin to form a glass sheet. The bottom surface of the glass in contact with the molten tin becomes almost perfectly flat due to gravity and surface tension, while the top surface of the glass not in contact with the molten tin also becomes almost perfectly flat due to the surface tension and weight of the glass itself. Since a high tin content on the surface of float glass reduces the adhesive strength with a thermoplastic resin sheet, it is preferable that the top surface of the float glass be in contact with the thermoplastic resin sheet. The glass member may be surface-treated. Examples of inorganic glass, particularly float glass, include soda-lime glass, borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass. In the present invention, even with fragile glass, the amount of glass scattered when the glass member is broken can be reduced. From this viewpoint, soda-lime glass is preferred.

[0053] The thickness of the first plate-like member is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.5 mm or more, and is preferably 5.0 mm or less, more preferably 3.0 mm or less.

[0054] (Second plate-shaped member) The second plate-shaped member is a glass member or an image display panel. When the second plate-shaped member is a glass member, the glass member of the second plate-shaped member can be the same as the glass member of the first plate-shaped member, so a description of the glass member of the second plate-shaped member will be omitted. Therefore, when the second plate-shaped member is a glass member, it is preferable that both the first and second plate-shaped members are inorganic glass, and float plate glass is more preferable. It is also preferable that both the first and second plate-shaped members are sorter-lime glass. Furthermore, when the second plate-shaped member is float plate glass, it is preferable that the top surface of the float plate glass contacts the thermoplastic resin sheet, but the bottom surface may also contact the thermoplastic resin sheet. The second plate-shaped member may be of the same type as the first plate-shaped member, or may be a different type.

[0055] Examples of the image display panel of the second plate-like member include a liquid crystal panel, an organic EL (Electroluminescence) panel, a mini LED (Light Emitting Diode) panel, a micro LED panel, and a nano LED panel, with the liquid crystal panel being preferred among these.

[0056] The image display panel may be provided with electrodes, sensors, etc. The electrodes are formed of conductive layers laminated on the surface of the image display panel. An example of a sensor is a touch sensor. A touch sensor is a sensor that detects touch input when a finger, a touch pen, or other object approaches or touches a substrate, and is configured with a conductive layer laminated on the substrate. When a finger, a touch pen, or other object approaches or touches the substrate, an electrical change such as capacitance, current, or voltage occurs in the conductive layer, and the touch sensor detects the touch input based on this electrical change. The conductive layer is not particularly limited, and any conventionally known electrode material having transparency can be used without any particular limitation. Examples include an indium tin oxide (ITO) conductive film, a tin oxide conductive film, a zinc oxide conductive film, and a polymer conductive film.

[0057] The laminate of the present invention can be produced, for example, by preparing a thermoplastic resin sheet and pressure-bonding a first plate-shaped member and a second plate-shaped member via the prepared thermoplastic resin sheet. For example, the laminate can be produced by stacking a first plate-shaped member, a thermoplastic resin sheet, and a second plate-shaped member in this order and pressure-bonding them. During pressure-bonding, the thermoplastic resin sheet may be appropriately heated, preferably to a temperature of 60°C or higher and 160°C or lower, more preferably 70°C or higher and 150°C or lower. Furthermore, pressure-bonding may be performed under pressure or under negative pressure. The pressure bonding to obtain the laminate may be performed using a vacuum bag, an autoclave, or a press other than these. Prior to the pressure bonding, temporary pressure bonding may be performed using a vacuum bag, nipper rolls, or the like.

[0058] [Image display device] The image display device of the present invention includes the laminate of the present invention. When the second plate-like member is a glass member, the image display device may further include an image display panel, and in this case, the laminate may be laminated on the surface (image display surface side) of the image display panel. In this case, the laminate serves as a cover member for the image display panel. Furthermore, when the second plate-like member is an image display panel, the laminate may serve as an image display device. In the image display device, the first plate-shaped member of the laminate serves as a cover glass and constitutes the outermost surface. The image display device may also be housed inside a housing or the like, as appropriate. When housed inside a housing, the entire image display device may be housed inside the housing, or parts other than the first plate-shaped member may be housed inside the housing, with part or all of the first plate-shaped member (i.e., the cover glass) being disposed outside the housing.

[0059] Furthermore, the image display device may include other components than the laminate and image display panel, such as a glass member other than the first and second plate-like members, an adhesive sheet or adhesive agent other than a thermoplastic resin sheet disposed between the first and second plate-like members, or a functional film such as a touch panel sheet. A touch panel sheet is a sheet having a touch sensor disposed on a glass plate or resin film. For example, when a touch panel sheet is provided, the touch panel sheet may be disposed between the image display panel and the laminate, and the touch panel sheet may be bonded to the laminate and the image display panel with an adhesive sheet or adhesive agent.

[0060] The image display device is preferably an in-vehicle display device, and is preferably provided in the front section in front of the driver's seat. In particular, the in-vehicle display device is preferably disposed below the windshield of the automobile, in front of either the driver's seat or the passenger seat. That is, the image display device is preferably disposed in a position where a conventional instrument panel is disposed. In the present invention, the front section in front of the driver's seat may be struck by the head of an occupant in the event of a vehicle collision or the like. However, the laminate of the present invention can reduce the amount of glass that scatters when the glass member shatters, as described above, and therefore can reduce the amount of glass that scatters even if the glass member shatters due to a collision with the head of an occupant. [Example]

[0061] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The methods for measuring and evaluating the various physical properties in the present invention are as follows.

[0062] <Degree of acetalization, hydroxyl value, and degree of acetylation> Measurement of ethylene group content (mass%) with hydroxyl groups The polyvinyl acetal resin used in each example and comparative example was used as the sample. 0.4 g of sample was weighed into a 200 mL Erlenmeyer flask with a stopper. 10.0 mL of pyridine-acetic anhydride mixture was added to the sample, and the mixture was heated and sonicated in a 90°C water bath to dissolve the sample in the pyridine-acetic anhydride mixture. A reflux condenser was attached to the Erlenmeyer flask, and the mixture was heated and refluxed in the water bath for 120 minutes. After the reaction, the condenser was rinsed with 25 mL of pyridine, and the reacted sample solution was cooled to room temperature. 20 mL of 1,2-dichloroethane was added to the cooled sample solution, followed by shaking. 50 mL of water was then added, followed by shaking, and the mixture was left at room temperature for 30 minutes. The sample solution was then subjected to potentiometric titration with 0.5 mol / L (0.5 N) sodium hydroxide solution. A blank test was performed in the same manner, except that no sample was used. The content (mass %) of ethylene groups bonded to hydroxyl groups in the sample was calculated using the following formula:

number

[0063] Measurement of ethylene group content (mass%) with acetyl groups 0.4 g of sample was weighed into a 200 mL Erlenmeyer flask with a stopper. 100 mL of ethanol was added to the sample, and the sample was dissolved in ethanol by heating and ultrasonication in a water bath at 90 °C. While shaking the Erlenmeyer flask, 10 mL of 0.2 mol / L (0.2 N) sodium hydroxide was added. A reflux condenser was attached to the Erlenmeyer flask, and the mixture was heated and refluxed in a water bath for 60 minutes. After the reaction, the condenser was rinsed with 25 mL of ethanol, and the reacted sample solution was cooled to room temperature. 10 mL of 0.2 mol / L (0.2 N) hydrochloric acid was added to the cooled sample solution, shaken well, and allowed to stand at room temperature for 30 minutes. The sample solution was then subjected to potentiometric titration with 0.1 mol / L (0.1 N) sodium hydroxide solution. A blank test was performed in the same manner, except that no sample was used. The content of acetyl-bonded ethylene groups (mass%) in the sample was calculated using the following formula:

number

[0064] Measurement of the content (mass%) of ethylene groups bound to butyral groups The content (mass%) of ethylene groups bonded to butyral groups was calculated based on the following formula using the content (mass%) of ethylene groups bonded to hydroxyl groups and the content (mass%) of ethylene groups bonded to acetyl groups determined by the above-mentioned methods.

number

[0065] Hydroxyl group amount, acetylation degree, acetalization degree (butyralization degree) The hydroxyl group amount (mol %), acetylation degree (mol %), and acetalization degree (mol %) were calculated based on the following formulas using the content of ethylene groups bonded to hydroxyl groups, the content of ethylene groups bonded to acetyl groups, and the content of ethylene groups bonded to butyral groups determined by the above-mentioned methods.

number

number

number

[0066] <Weight average molecular weight> The polyvinyl acetal resin used in each example and comparative example was dissolved at a concentration of 0.05% by mass in N-methyl-2-pyrrolidone solution containing lithium bromide to a concentration of 10 mM. The solution was filtered using a syringe filter (Merck, Millex-LH 0.45 μm) and then subjected to molecular weight measurement using gel permeation chromatography (Waters, e2690). The number-average molecular weight (Mn) and weight-average molecular weight (Mw) were calculated using a molecular weight calibration curve prepared using monodisperse polystyrene standards, and the molecular weight distribution (Mw / Mn) was also determined. A Shodex GPC KF-806L column (Showa Denko K.K.) was used, and the eluent was N-methyl-2-pyrrolidone solution containing lithium bromide to a concentration of 10 mM.

[0067] <Storage modulus> The storage modulus of the thermoplastic resin sheet was calculated by measuring the dynamic viscoelastic spectrum using a DVA-200 (manufactured by IT Measurement & Control Co., Ltd.) under the following conditions: shear mode: 10 Hz, strain: 0.1%, temperature range: -100°C to 100°C, and heating rate: 10°C / min.

[0068] <Peel strength measurement> (1) Preparation of laminate for peel strength measurement A glass plate 210 (25 mm × 300 mm), a polyimide Kapton film 220 (25 mm × 300 mm, 50 μm thick, no release treatment on both sides), a thermoplastic resin sheet 230 (25 mm × 300 mm), a polyimide Kapton film 240 (25 mm × 165 mm, 50 μm thick, no release treatment on both sides), and a glass plate 250 (25 mm × 300 mm) were laminated as shown in FIG. 5( a) to produce a laminate 200. The thermoplastic resin sheet 230 and the glass plate 250 were laminated such that the side of the glass plate 250 that was not in contact with the molten tin was in contact with the thermoplastic resin sheet 230. The obtained laminate 200 was then placed in a rubber bag and subjected to vacuum suction to remove any air remaining between the glass plates 210 and 250 and the thermoplastic resin sheet 230. The bag was then pre-bonded at 80°C to obtain a pre-press-bonded laminate. Next, the pre-press-bonded laminate 200 was placed in an autoclave and pressed under conditions of 140°C and 1.3 MPa to prepare a laminate 200 for peel strength measurement. Then, since the glass plate 210 was not bonded to the thermoplastic resin sheet 230, the glass plate 210 was removed from the laminate 200 to prepare a measurement sample 201 as shown in Fig. 5(b). The glass plates 210 and 250 were soda lime float glass plates manufactured by Central Glass Co., Ltd., with a size of 25 mm x 300 mm and a thickness of 2.5 mm.

[0069] (2) Peel strength measurement Measurements were carried out in accordance with JIS K6854-2:1999 (ISO8510-2:1990) using a tensile testing machine (Instron Model 5965 Universal Testing Machine or an equivalent). 5(c), one end of the portion of the measurement sample 201 that is not bonded to the glass plate 250 is held with one jig (not shown), and the other jig (not shown) holds the adherend, the glass plate 250. In this state, the thermoplastic resin sheet was peeled off in a 180° direction at a pulling rate of 100 mm / min, and the peel strength (N / 25 mm) between the thermoplastic resin sheet and the glass surface at 23°C was measured.

[0070] <Glass mass loss rate before and after collision test> (1) Preparation of the laminate (Examples 1 to 3) As shown in FIG. 4 , a laminate was prepared by laminating a glass plate 2 and a glass plate 4 via a thermoplastic resin sheet 3 according to each example. The thermoplastic resin sheet 3 and the glass plates 2 and 4 were laminated together such that the surface of the glass plate 2 that had been in contact with the molten tin was in contact with the thermoplastic resin sheet 3, and the surface of the glass plate 4 that had not been in contact with the molten tin was in contact with the thermoplastic resin sheet 3. The resulting laminate was then placed in a rubber bag and subjected to vacuum suction to remove any air remaining between the glass plate and the thermoplastic resin sheet. The pre-bonded laminate was then pre-bonded at approximately 80°C to obtain a pre-bonded laminate. The pre-bonded laminate was then placed in an autoclave and bonded under conditions of 140°C and 1.3 MPa to prepare a laminate 1D for impact test measurement. The PVB used for the thermoplastic resin sheet was a resin described below, and the following materials were used for the glass plates 2 and 4. The thermoplastic resin sheets used were of a size such that the distances extending outward from the periphery of the thermoplastic resin sheet relative to the periphery of the glass plate 2 and the periphery of the glass plate 4 were the distances shown in Table 1. Glass plate 2: Osaka Glass Industry Co., Ltd., soda lime glass, size: 300 mm x 300 mm, thickness: 1.1 mm Glass plate 4: Osaka Glass Industry Co., Ltd., soda lime glass, size: 300 mm x 300 mm, thickness: 1.1 mm

[0071] (Comparative Examples 4 to 6) As shown in FIG. 7 , a laminate was prepared by laminating a glass plate 2 and a glass plate 4 via a thermoplastic resin sheet 3 according to each comparative example. The thermoplastic resin sheet 3 and the glass plates 2 and 4 were laminated together such that the surface of the glass plate 2 that had been in contact with the molten tin was in contact with the thermoplastic resin sheet 3, and the surface of the glass plate 4 that had not been in contact with the molten tin was in contact with the thermoplastic resin sheet 3. The resulting laminate was then placed in a rubber bag and evacuated under reduced pressure to remove any air remaining between the glass plate and the thermoplastic resin sheet. The pre-bonded laminate was then pre-bonded at approximately 80°C to obtain a pre-bonded laminate. The pre-bonded laminate was then placed in an autoclave and bonded under conditions of 140°C and 1.3 MPa to prepare a laminate 1E for impact test measurement. The PVB used for the thermoplastic resin sheet was a resin described below, and the following materials were used for the glass plates 2 and 4. The thermoplastic resin sheets used were of a size such that the distances extending outward from the periphery of the thermoplastic resin sheet relative to the periphery of the glass plate 2 and the periphery of the glass plate 4 were the distances shown in Table 1. Furthermore, when the outer periphery of the glass plate 2 and the outer periphery of the glass plate 4 extend outward relative to the outer periphery of the thermoplastic resin sheet, the extending distance is defined as the negative absolute value of the extending distance. This indicates that when the extending distance is positive, the outer periphery of the thermoplastic resin sheet 3 extends outward relative to the outer periphery of the glass plate 2 and the outer periphery of the glass plate 4, and when the extending distance is negative, the outer periphery of the glass plate 2 and the outer periphery of the glass plate 4 extend outward relative to the outer periphery of the thermoplastic resin sheet. Glass plate 2: Osaka Glass Industry Co., Ltd., soda lime glass, size: 300 mm x 300 mm, thickness: 1.1 mm Glass plate 4: Osaka Glass Industry Co., Ltd., soda lime glass, size: 300 mm x 300 mm, thickness: 1.1 mm

[0072] Examples 4 to 6 Laminates of Examples 4 to 6 were produced in the same manner as the laminates of Examples 1 to 3, except that the size of the glass plate 4 was changed from 300 mm×300 mm to 280 mm×280 mm.

[0073] (Comparative Examples 1 to 3) The laminates of Comparative Examples 1 to 3 were produced in the same manner as the laminates of Comparative Examples 4 to 6, except that the size of the glass 4 was changed from 300 mm × 300 mm to 280 mm × 280 mm, as in the laminate 1F shown in Figure 8.

[0074] (2) Impact test (2-1) The initial mass (W1) of the laminate 1D (1E, 1F) for the impact test was measured. (2-2) The laminate 1D (1E) for impact testing was left in a thermostatic chamber set at a temperature of 23°C until the temperature of the laminate 1D (1E, 1F) reached 23°C. (2-3) The laminate 1D (1E, 1F) for impact testing, a urethane rubber frame 310 (Shore A hardness 70, size: 300 mm × 300 mm, height 10 mm, width 20 mm), and a metal frame 320 (size: 360 mm × 360 mm, height 50 mm, width 50 mm) were arranged as shown in Figure 6. At this time, the glass plate 2 side of the laminate 1D (1E, 1F) for impact testing was facing up. The laminate and urethane rubber for measurement, and the urethane rubber and metal frame were bonded and fixed together with double-sided tape (manufactured by Nitto Denko Corporation, product name: Foam Butyl Rubber Double-Sided Adhesive Tape No. 541, width 20 mm) (not shown). (2-4) An iron ball 330 with a mass of 110.69 g was dropped from a height of 9 m onto a position within a distance of 1 cm to 2 cm from the edge of the laminate 1D (1E, 1F). At this time, the impact energy of the iron ball 330 on the laminate 1D (1E, 1F) was 9.78 J. (2-5) The glass plate peeled off by the falling iron ball 300 was removed from the stack 1D (1E, 1F). (2-6) After removing the glass plates that had peeled off due to the falling of the iron ball 330, the post-test mass (W2) of the laminate 1D (1E, 1F) was measured. (2-7) The mass loss rate (%) (= (W1 - W2) ÷ W1 × 100) was calculated by subtracting the mass after the test (W2) from the initial mass (W1) and dividing the result by the initial mass (W1).

[0075] <Impact test evaluation> The results of the glass mass loss rate before and after the collision test were evaluated according to the following criteria. 〇: Glass mass loss rate is 0.12% or less ×: The mass loss rate of the glass is more than 0.12%

[0076] (Preparation of polyvinyl butyral resin) The polyvinyl butyral resins used in the examples and comparative examples were prepared as follows. A reactor equipped with a stirrer was charged with 1800 ml of ion-exchanged water and 200 g of polyvinyl alcohol (average degree of polymerization 1700, degree of saponification 99 mol%), and the mixture was heated and dissolved while stirring to obtain a polyvinyl alcohol solution. Next, 30% hydrochloric acid was added as a catalyst to this solution so that the hydrochloric acid concentration was 0.2% by mass. After adjusting the temperature to 15°C, n-butylaldehyde was added with stirring so that the concentration was 10 mol%. Subsequently, n-butylaldehyde was added so that the concentration was 60 mol%, resulting in the precipitation of a white granular polyvinyl butyral resin. Ten minutes after the precipitation, 30% hydrochloric acid was added so that the hydrochloric acid concentration was 1.8% by mass. The mixture was then heated to 65°C and aged for 2 hours at each aging temperature. Next, the solution was cooled and neutralized, and then the polyvinyl butyral resin was washed with water and dried to obtain a resin (polyvinyl butyral resin).

[0077] The plasticizers, antioxidants, ultraviolet absorbers, moisture resistance improvers and adhesion modifiers used in the examples and comparative examples are as follows. (1) Plasticizer 3GO: Triethylene glycol-di-2-ethylhexanoate (2) Antioxidants BHT: 2,6-di-t-butyl-p-cresol (3) UV absorbers Tinuvin 326: 2-(2'-hydroxy-3'-t-butyl-5-methylphenyl)-5-chlorobenzotriazole, manufactured by BASF

[0078] (Preparation of thermoplastic resin sheet) 100 parts by mass of polyvinyl butyral resin (PVB) was mixed with 35 parts by mass of a plasticizer (triethylene glycol-di-2-ethylhexanoate: 3GO), 0.2 parts by mass of an antioxidant (BTH), and 0.2 parts by mass of an ultraviolet absorber (Tinuvin 326) and extruded in an extruder to produce a film-like thermoplastic resin sheet with a thickness of 380 μm.

[0079] [Table 1]

[0080] In the laminates of Examples 1 to 6 described above, when viewed in a plane, the outer periphery of the thermoplastic resin sheet 3 was either in the same position as the outer periphery of the glass plates 2 and 4 or extended outward relative to the outer periphery of the glass plates 2 and 4, so the mass loss rate of the glass in the collision test was small. On the other hand, in the laminates of Comparative Examples 1 to 3, the outer periphery of the glass plate 2 extended outward relative to the outer periphery of the thermoplastic resin sheet 3 in plan view, and therefore the mass loss rate of the glass was large in the crash test. In the laminates of Comparative Examples 4 to 6, the outer peripheries of the glass plates 2 and 4 extended outward relative to the outer periphery of the thermoplastic resin sheet 3 in plan view, and therefore the mass loss rate of the glass was large in the crash test. [Explanation of symbols]

[0081] 1, 1A to 1F laminate 2. First plate-shaped member (glass plate) 3 Thermoplastic resin sheet 4. Second plate-shaped member (glass plate) 21 Outer periphery of first plate-shaped member (glass plate) 31 Outer periphery of thermoplastic resin sheet 41 Outer periphery of second plate-shaped member (glass plate) 200 laminate 201 Measurement sample 210,250 glass plates 220,240 Polyimide Kapton Film 310,410,430 Urethane rubber frame 320,420,440 Metal frame 330 Iron Ball

Claims

1. a first plate-shaped member, a second plate-shaped member, and a thermoplastic resin sheet containing a thermoplastic resin disposed between the first plate-shaped member and the second plate-shaped member; the first plate-like member is a glass member, the second plate-like member is a glass member or an image display panel, A laminate in which, when viewed in a plane, the outer periphery of the thermoplastic resin sheet is at the same position as the outer periphery of the first plate-shaped member or extends outward relative to the outer periphery of the first plate-shaped member, and the outer periphery of the thermoplastic resin sheet is at the same position as the outer periphery of the second plate-shaped member or extends outward relative to the outer periphery of the second plate-shaped member.

2. The storage modulus of the thermoplastic resin sheet at 23°C (G'(23°C)) is 1 x 10 ６ Pa or more 2×10 ７ Pa or less, The storage modulus of the thermoplastic resin sheet at 100°C (G'(100°C)) is 1 x 10 ４ Pa or more 3×10 ５ The laminate according to claim 1, wherein the modulus is 0.05 Pa or less.

3. 3. The laminate according to claim 1, wherein the thermoplastic resin sheet has a peel strength of 10 N / 25 mm or more relative to the first plate-like member.

4. 3. The laminate according to claim 1, wherein the glass mass loss rate before and after the following collision test is 0.12% or less. (Crash test method) (1) The first plate-shaped member of the laminate is replaced with a glass plate having the same size as the first plate-shaped member and a thickness of 1.1 mm, so that the arrangement of the first plate-shaped member relative to the thermoplastic resin sheet is the same, and the second plate-shaped member of the laminate is replaced with a glass plate having the same size as the second plate-shaped member and a thickness of 1.1 mm, so that the arrangement of the second plate-shaped member relative to the thermoplastic resin sheet is the same, to prepare a test sample. (2) The initial mass of the test sample is measured. (3) The test sample is left in a thermostatic chamber set at 23°C until the temperature of the test sample reaches 23°C. (4) After placing the test sample horizontally with the first plate-shaped member on top, an iron ball with a mass of 110.69 g is dropped from a height of 9 m onto a position within a distance of 1 cm to 2 cm inward from the edge of the test sample. (5) Remove the glass plate that has been peeled off by the falling iron ball. (6) After removing the glass plate that was peeled off by the falling iron ball, the mass of the test sample after the test is measured. (7) The mass reduction rate (%) is calculated by subtracting the mass after the test from the initial mass and dividing the obtained value by the initial mass.

5. 3. The laminate according to claim 1, wherein the outer periphery of the thermoplastic resin sheet extends outward by a distance of 1 mm or more and 15 mm or less from the outer periphery of the plate-like member having a smaller projected area than the projected area of ​​the first plate-like member when projected in the thickness direction and the projected area of ​​the second plate-like member when projected in the thickness direction.

6. The laminate according to claim 1 or 2, wherein, in a plan view, the outer periphery of the thermoplastic resin sheet extends outward from the outer periphery of the first plate-like member by a distance of 0 mm or more and 5 mm or less.

7. 3. The laminate according to claim 1, wherein the first plate-shaped member and the second plate-shaped member are made of inorganic glass.

8. 3. The laminate according to claim 1, wherein the thermoplastic resin is a polyvinyl acetal resin, an ethylene-vinyl acetate copolymer resin (EVA), a polyurethane resin (PU), or an ionomer resin.

9. The laminate according to claim 1 or 2, wherein, in a plan view, the outer periphery of the first plate-like member, the outer periphery of the thermoplastic resin sheet, and the outer periphery of the second plate-like member are located at the same position.

10. An image display device comprising the laminate according to claim 1 or 2.

Images