Laminate

Abstract

This laminate comprises thermoplastic resin sheets and separation layers, the projected area of the separation layers being equal to or greater than the projected area of the thermoplastic resin sheets.　The present invention makes it possible to provide a laminate in which blocking of the thermoplastic resin sheets can be suppressed.

Description

Laminate

[0001] The present invention relates to a laminate.

[0002] In image display devices such as in-vehicle displays, optically transparent adhesives (OCAs) are used to bond their components together (see, for example, Patent Document 1). OCAs are generally made of acrylic resins or the like, and can secure the components of the image display device while ensuring visibility. Because OCAs are a type of pressure-sensitive adhesive, they are generally stored and transported at room temperature and used in the manufacture of image display devices.

[0003] JP 2013-178332 A

[0004] In recent years, image display devices such as in-vehicle displays have been desired to have higher impact absorption and better shatterproof properties for glass and other objects than conventional devices. Therefore, the present inventors investigated the use of an interlayer filler made of a thermoplastic resin sheet containing, for example, a polyvinyl acetal resin, instead of OCA. When using thermoplastic resin sheets in existing image display device manufacturing equipment, from the standpoint of ease of handling, it is desirable to store multiple thermoplastic resin sheets cut to a predetermined size in a stacked manner and peel them off one by one when used. However, it was found that this can cause problems such as blocking between the thermoplastic resin sheets, reducing production efficiency.

[0005] Therefore, an object of the present invention is to provide a laminate that can suppress blocking of a thermoplastic resin sheet.

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that the above-mentioned problems can be solved by a laminate having a thermoplastic resin sheet and a separation layer, in which the projected area of ​​the separation layer is equal to or greater than the projected area of ​​the thermoplastic resin sheet, and have completed the present invention as described below. That is, the gist of the present invention is as follows: [1] to

[14]

[0007] [1] A laminate comprising a thermoplastic resin sheet and a separation layer, wherein the projected area of ​​the separation layer is equal to or greater than the projected area of ​​the thermoplastic resin sheet. [2] The laminate according to [1] above, wherein the separation layer is film-like. [3] The laminate according to [1] or [2] above, wherein the separation layer has a flat portion and a protrusion. [4] The laminate according to any one of [1] to [3] above, wherein the adhesive strength between the thermoplastic resin sheet and the separation layer is 0.003 N / 25 mm or more and 0.02 N / 25 mm or less. [5] The laminate according to any one of [1] to [4] above, wherein the tensile modulus of the separation layer is 2000 MPa or more and 5000 MPa or less. [6] The laminate according to any one of [1] to [5] above, wherein the separation layer is flat. [7] The laminate according to any one of [1] to [6] above, wherein the area of ​​the surface of the separation layer in contact with the thermoplastic resin sheet is equal to or greater than the area of ​​the surface of the thermoplastic resin sheet on the side in contact with the separation layer. [8] The laminate according to any one of [1] to [7] above, wherein the projected area of ​​the separation layer is 1.1 to 2 times the projected area of ​​the thermoplastic resin sheet. [9] The laminate according to any one of [1] to [8] above, wherein the center of the thermoplastic resin sheet and the center of the separation layer coincide with each other.

[10] The laminate according to any one of [1] to [9] above, wherein the thermoplastic resin sheet contains a polyvinyl acetal resin.

[11] The laminate according to any one of [1] to

[10] above, wherein the thickness of the thermoplastic resin sheet is 100 μm to 1000 μm.

[12] The laminate according to any one of [1] to

[11] above, wherein the thermoplastic resin sheet is an interlayer filler.

[13] The laminate according to any one of [1] to

[12] above, wherein the thermoplastic resin sheets and the separation layers are alternately laminated.

[14] The laminate according to any one of [1] to

[13] above, further comprising a support layer on at least one of the upper and lower ends.

[0008] According to the present invention, it is possible to provide a laminate capable of suppressing blocking of a thermoplastic resin sheet.

[0009] Fig. 1 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. Fig. 2 is a diagram schematically illustrating a region of a thermoplastic resin sheet and a separation layer. Fig. 3 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. Fig. 4 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. Fig. 5 is a cross-sectional view schematically illustrating the shape of a separation layer. Fig. 6 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. Fig. 7 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention.

[0010] The laminate of the present invention includes a thermoplastic resin sheet and a separation layer, and the separation layer has a projected area equal to or greater than the projected area of ​​the thermoplastic resin sheet. Hereinafter, the present invention will be described with reference to the drawings, but the contents of the present invention are not limited to the drawings.

[0011] FIG. 1 shows one embodiment of the laminate of the present invention. The laminate 10 of FIG. 1 includes a thermoplastic resin sheet 12 and a separation layer 11, with the separation layer 11 laminated on one side of the thermoplastic resin sheet 12. In the laminate 10, the projected area S1 of the separation layer 11 projected in the thickness direction T of the laminate is equal to or greater than the projected area S2 of the thermoplastic resin sheet 12 projected in the thickness direction T of the laminate. If the projected area S1 of the separation layer 11 is less than the projected area S2 of the thermoplastic resin sheet 12, for example, when the laminate 10 is stacked, the thermoplastic resin sheets are likely to block each other. This is thought to be because the edges of the thermoplastic resin sheets are not supported by the separation layer, causing deflection at the edges and resulting in blocking between the edges of the thermoplastic resin sheets.

[0012] Here, the projected area of ​​the separation layer corresponds to the area of ​​the region obtained by projecting the separation layer of the laminate in the thickness direction of the laminate, and the projected area of ​​the thermoplastic resin sheet corresponds to the area of ​​the region obtained by projecting the thermoplastic resin sheet of the laminate in the thickness direction of the laminate.

[0013] 2 shows a view of the laminate 10 as seen from above, and when viewed from above in the thickness direction, the region where the separation layer 11 exists (the solid line portion in FIG. 2) corresponds to the projected area S1, and the region where the thermoplastic resin sheet 12 exists (the dotted line portion in FIG. 2) corresponds to the projected area S2. From the viewpoint of suppressing blocking, it is preferable that the region where the thermoplastic resin sheet 12 exists (the dotted line portion in FIG. 2) be included within the region where the separation layer 11 exists (the solid line portion in FIG. 2) when viewed from above in the thickness direction.

[0014] The projected area S1 of the separation layer 11 is preferably 1.1 to 2 times the projected area S2 of the thermoplastic resin sheet 12. Having the projected area S1 be 1.1 times or more the projected area S2 makes it easier to suppress blocking of the thermoplastic resin sheet. Furthermore, when transporting the laminate, the end portions of the separation layer can be gripped, making it easy to hold and preventing stress from being applied to the thermoplastic resin sheet, which can cause shrinkage. Furthermore, adhesion of the thermoplastic resin sheet to a gripping tool can be suppressed, preventing wrinkles from occurring. Having the projected area S1 be 2 times or less the projected area S2 improves handleability and reduces the amount of separation layer used, thereby lowering manufacturing costs. From the above perspectives, the projected area S1 of the separation layer 11 is more preferably 1.1 to 1.8 times the projected area S2 of the thermoplastic resin sheet 12, and even more preferably 1.2 to 1.6 times.

[0015] In addition, from the viewpoint of suppressing blocking of the thermoplastic resin sheet, it is preferable that the projected area S1 of the separation layer 11 is equal to or greater than the projected area S2 of the thermoplastic resin sheet 12, while the area of ​​the surface of the separation layer 11 in contact with the thermoplastic resin sheet 12 is equal to or greater than the area of ​​the surface of the thermoplastic resin sheet 12 in contact with the separation layer 11.

[0016] The laminate of the present invention may have a plurality of thermoplastic resin sheets and / or separation layers. For example, as shown in FIG. 3, a laminate in which thermoplastic resin sheets and separation layers are alternately laminated is preferred. FIG. 3 shows a laminate 20 in which a separation layer 11a, a thermoplastic resin sheet 12a, a separation layer 11b, a thermoplastic resin sheet 12b, and a separation layer 11c are laminated in this order. Such a laminate in which thermoplastic resin sheets and separation layers are alternately laminated can be used as an adhesive for various components such as image display devices by peeling the thermoplastic resin sheets one by one during use. The total number of thermoplastic resin sheets and separation layers constituting the laminate is not particularly limited, but is, for example, 25 to 200 sheets, preferably 50 to 150 sheets.

[0017] Furthermore, in a laminate in which thermoplastic resin sheets and separation layers are alternately stacked, the multiple thermoplastic resin sheets do not have to be the same size, and the multiple separation layers do not have to be the same size. For example, as in the laminate 30 shown in Figure 4, some of the separation layers may be smaller than the other separation layers, or some of the thermoplastic resin sheets may be smaller than the other thermoplastic resin sheets. In this case, the projected area S1 of the separation layer in the present invention reflects the projected area of ​​the largest separation layer among the multiple separation layers, and the projected area S2 of the thermoplastic resin sheet in the present invention reflects the projected area of ​​the largest thermoplastic resin sheet among the multiple thermoplastic resin sheets.

[0018] In a laminate in which thermoplastic resin sheets and separation layers are alternately stacked, it is preferable that each of the multiple thermoplastic resin sheets has the same material and shape, and it is preferable that each of the multiple separation layers has the same material and shape.

[0019] The spacing layer 11 in the laminate of the present invention may be composed of only a flat portion F, as shown in the left diagram of FIG. 5 , or may have a flat portion F and protrusions P, as shown in the right diagram of FIG. 5 . The protrusions P may be formed anywhere on the flat portion F of the spacing layer 11, and the number of protrusions P may be one or more. The protrusions are preferably formed continuously so as to surround the outer periphery of one surface of the flat portion F. The height h of the protrusions is preferably 5 μm or more and 500 μm or less higher than the thickness of the thermoplastic resin sheet. Specifically, the height h of the protrusions is, for example, 105 μm or more and 1500 μm or less, preferably 110 μm or more and 1350 μm or less. By using a spacing layer having a flat portion and protrusions, a laminate 40 of the present invention can be formed, for example, as shown in FIG. 6 , which includes a spacing layer 11 having protrusions. By stacking multiple spacing layers 11, the protrusions F can form spaces, and a thermoplastic resin sheet 12 can be placed within the spaces. By appropriately adjusting the height of the protrusions F, it is also possible to prevent the upper surface of the thermoplastic resin sheet 12 from coming into contact with the separation layer 11. In this case, the separation layer 11 can be easily peeled off.

[0020] (Support Layer) FIG. 7 shows a laminate 50 having plate-shaped support layers 13 at the upper and lower ends of the laminate. Having such support layers in the laminate allows the separation layer and thermoplastic resin sheet included in the laminate to be properly supported and protected during storage, transportation, and the like. While FIG. 7 shows an embodiment in which the support layers 13 are provided at both the upper and lower ends of the laminate, the present invention is not limited to this embodiment. When using a support layer 13, the support layer 13 may be provided at at least one of the upper and lower ends of the laminate. In particular, the support layer 13 is preferably provided at both the upper and lower ends of the laminate. In addition, in the laminate 50 shown in FIG. 7, the support layer 13 is provided so as to contact the separation layer 11, but the present invention is not limited to this embodiment. The support layer 13 may be provided so as to contact the thermoplastic resin sheet 12. In particular, the support layer 13 is preferably provided so as to contact the separation layer 11 because the support layer 13 can be easily peeled off.

[0021] The size of the support layer 13 is not particularly limited, but is preferably equal to or larger than that of the separation layer 11. In other words, the projected area of ​​the support layer 13 projected in the thickness direction of the laminate is preferably equal to or larger than the projected area of ​​the separation layer projected in the thickness direction of the laminate.

[0022] The thickness of the support layer is not particularly limited, but is preferably thicker than the spacing layer. The thickness of the support layer is preferably 1 mm or more and 10 mm or less, more preferably 1.5 mm or more and 8 mm or less, and even more preferably 4 mm or more and 6 mm or less.

[0023] The support layer may be made of metal or resin, but is preferably made of resin from the viewpoint of reducing the weight of the laminate. Among resin materials, plastic cardboard is particularly preferred. Plastic cardboard is a plate-shaped material and has a hollow structure like general cardboard. Therefore, using plastic cardboard as the support layer makes it easier to reduce the weight of the laminate and transport it. Furthermore, since plastic cardboard has excellent durability, water resistance, heat insulation, etc., it can adequately protect the separation layer and thermoplastic resin sheet. The resin material constituting the plastic cardboard is not particularly limited, and resins such as polypropylene, polycarbonate, and polystyrene can be used.

[0024] (Center Point) In the laminate of the present invention, it is preferable that the center of the thermoplastic resin sheet and the center of the separation layer coincide. When one or both of the thermoplastic resin sheets and the separation layer are present, it is preferable that the centers of all the thermoplastic resin sheets coincide with the centers of all the separation layers. This makes it easier to suppress blocking of the thermoplastic resin sheet, and also improves the uniformity of the area where the laminate is gripped (the end of the separation layer), improving handleability. Here, "the centers coincide" not only means that all the center points of the thermoplastic resin sheets and the separation layers completely coincide (overlap) when viewed from above, but also includes that all the center points of the thermoplastic resin sheets and the separation layers when viewed from above are included in a circular area with a radius of 20 mm or less, preferably included in a circular area with a radius of 15 mm or less, more preferably included in a circular area with a radius of 10 mm or less, even more preferably included in a circular area with a radius of 5 mm or less, and even more preferably included in a circular area with a radius of 1 mm or less. In particular, it is particularly preferable that all the center points of the thermoplastic resin sheets and the separation layers completely coincide (overlap) when viewed from above.

[0025] (Adhesive Strength) In the laminate of the present invention, the adhesive strength between the thermoplastic resin sheet and the separation layer is preferably 0.003 N / 25 mm or more and 0.02 N / 25 mm or less, more preferably 0.005 N / 25 mm or more and 0.018 N / 25 mm or less, and even more preferably 0.007 N / 25 mm or more and 0.015 N / 25 mm or less. When the adhesive strength between the thermoplastic resin sheet and the separation layer is below the upper limit, the thermoplastic resin sheet is easily peeled from the separation layer, preventing shrinkage of the thermoplastic resin sheet due to stress during peeling. On the other hand, when the adhesive strength between the thermoplastic resin sheet and the separation layer is above the lower limit, the thermoplastic resin sheet becomes slippery, for example, when the laminate is tilted, which makes it more likely to wrinkle. The adhesive strength between the thermoplastic resin sheet and the separation layer is the 180° peel strength, which can be measured by the method described in the examples.

[0026] In the case of a laminate using a plurality of thermoplastic resin sheets and / or separation layers, there will be a plurality of interfaces between the thermoplastic resin sheets and the separation layers. In this case, it is preferable that at least one of the interfaces has an adhesive strength within the above-mentioned range, more preferably that 50% or more of the interfaces have an adhesive strength within the above-mentioned range, even more preferably that 80% or more of the interfaces have an adhesive strength within the above-mentioned range, and even more preferably that all of the interfaces have an adhesive strength within the above-mentioned range.

[0027] (Separation layer) The tensile modulus of the separation layer in the present invention is preferably 2000 MPa or more and 5000 MPa or less. When the tensile modulus of the separation layer is 2000 MPa or more, the separation layer does not bend excessively when handling the laminate, so the thermoplastic resin sheet can accommodate bending and the occurrence of wrinkles is suppressed. When the tensile modulus of the separation layer is 5000 MPa or less, the appropriate modulus of elasticity makes it easy to peel. From this perspective, the tensile modulus of the separation layer is more preferably 2300 MPa or more and 4700 MPa or less, and even more preferably 2500 MPa or more and 4500 MPa or less. The tensile modulus can be measured by the method described in the examples.

[0028] The shape of the separation layer in the present invention is not particularly limited, but is preferably film-like from the viewpoint of easy peeling. The film-like separation layer is not particularly limited, and conventionally known separators and release liners can be used. Among these, it is preferable to use a biaxially stretched film as the separation layer from the viewpoint of ease of adjustment to the desired tensile modulus and film strength. A biaxially stretched film is a film stretched in both the MD direction (machine direction) and the TD direction (transverse direction). The separation layer is preferably flat and preferably sheet-like. The separation layer preferably has a shape with no thickness deviation and preferably does not have a thickness deviation. The thickness of the separation layer is not particularly limited, but is, for example, 10 to 500 μm, preferably 50 to 200 μm. The shape of the separation layer is not particularly limited, but may be rectangular or circular. For example, in the case of a rectangular shape, the size of the separation layer may be adjusted appropriately according to the size of the thermoplastic resin sheet used within a range that satisfies the relationship between the projected areas of the separation layer and the thermoplastic resin sheet, and may be, for example, 15 mm to 40 mm longer than the longitudinal length of the thermoplastic resin sheet and 15 mm to 40 mm longer than the lateral length. In the case of a circular shape, the size of the separation layer may be, for example, 15 mm to 40 mm longer than the radius of the thermoplastic resin sheet.

[0029] The material of the separation layer in the present invention may be metal or resin, but is preferably resin. Among resins, polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate, and polyolefin-based resins such as polyethylene and polypropylene are preferred. Among them, polyester-based resins are more preferred, and polyethylene terephthalate (PET) is more preferred, from the viewpoint of ease of adjusting the tensile modulus and adhesive strength to the desired range. When a thermoplastic resin sheet containing a polyvinyl acetal resin described below is used as the thermoplastic resin sheet, using the PET as the separation layer makes it easier to adjust the tensile modulus and adhesive strength to the desired range.

[0030] (Thermoplastic Resin Sheet) The thermoplastic resin sheet in the laminate of the present invention contains a thermoplastic resin and is a sheet formed from a thermoplastic resin.

[0031] Examples of thermoplastic resins include (meth)acrylic resins, polyvinyl acetal resins, polyvinyl alcohol resins (PVA), polyolefin thermoplastic elastomers (POE), polyurethane thermoplastic elastomers (TPU), cyclic olefin resins (COP) such as cyclic olefin copolymers (COC), ionomer resins, saponified ethylene-vinyl acetate copolymers (EVOH), ethylene-methacrylic acid copolymer resins, styrene-isoprene copolymer resins, and styrene-butadiene copolymer resins. (Meth)acrylic refers to both acrylic and methacrylic. These thermoplastic resins may be used alone or in combination. Among these thermoplastic resins, polyvinyl acetal resins are preferred due to their high impact absorption and excellent shatterproof properties for glass and the like. The use of polyvinyl acetal resins as the thermoplastic resin will be described in more detail below.

[0032] (Polyvinyl acetal resin) Examples of polyvinyl acetal resins include polyvinyl acetal resins 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-butyl aldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexyl aldehyde, n-octyl aldehyde, n-nonyl aldehyde, n-decyl aldehyde, formaldehyde, acetaldehyde, and benzaldehyde. 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.

[0033] Polyvinyl alcohol (PVA), which is used as a raw material for polyvinyl acetal resins, is obtained, for example, by saponifying a polyvinyl ester such as polyvinyl acetate. The degree of saponification of polyvinyl alcohol is generally 70 to 99.9 mol%. Polyvinyl acetal resins may be used singly or in combination of two or more. The average degree of polymerization of PVA is preferably 200 or more, more preferably 500 or more, even more preferably 1000 or more, and even more preferably 1500 or more. The average degree of polymerization of PVA is preferably 5000 or less, more preferably 4000 or less, even more preferably 3500 or less, and even more preferably 2500 or less. The average degree of polymerization of polyvinyl alcohol is determined by a method in accordance with JIS K6726 "Testing Methods for Polyvinyl Alcohol."

[0034] The amount of hydroxyl groups in the polyvinyl acetal resin is preferably 15 mol% or more and 38 mol% or less. By setting the amount of hydroxyl groups to 15 mol% or more, adhesiveness and impact resistance tend to be improved. Furthermore, by setting the amount of hydroxyl groups to 38 mol% or less, excessive hardness is prevented. From the viewpoint of adhesiveness to glass members and the like, the amount of hydroxyl groups is more preferably 20 mol% or more, and even more preferably 25 mol% or more. Furthermore, the amount of hydroxyl groups is more preferably 35% 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 preferably 15 mol% or more and 38 mol% or less. Furthermore, it is more preferably 20 mol% or more, even more preferably 25 mol% or more, and even more preferably 35% or less, and even more preferably 33 mol% or less. The amount of hydroxyl groups in the polyvinyl acetal resin is the 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, expressed as a percentage. The amount of ethylene groups to which hydroxyl groups are bonded can be measured, for example, in accordance with JIS K6728 "Testing Methods for Polyvinyl Butyral."

[0035] The amount of acetal groups in the polyvinyl acetal resin is preferably 47 mol% or more and 85 mol% or less. The amount of acetal groups is more preferably 55 mol% or more, even more preferably 60 mol% or more, and more preferably 80 mol% or less, even more preferably 75 mol% or less. Note that, when the acetal groups are butyral groups and the polyvinyl acetal resin is a polyvinyl butyral resin, the amount of acetal groups refers to the degree of butyralization.

[0036] The amount of acetal groups can be determined, for example, by subtracting the amount of ethylene groups having hydroxyl groups and the amount of ethylene groups having acetyl groups from the total amount of ethylene groups in the main chain, dividing the result by the total amount of ethylene groups in the main chain to obtain a molar fraction expressed as a percentage. The amount of acetal groups (amount of butyral groups) may be calculated from the results of measurements performed, for example, according to JIS K6728 "Testing Methods for Polyvinyl Butyral."

[0037] The amount of acetyl groups in the polyvinyl acetal resin 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 amount of acetyl groups is below the upper limit, the moisture resistance of the laminate is increased. Furthermore, the amount of acetyl groups is not particularly limited, but is preferably 0.01 mol% or more, more preferably 0.1 mol% or more. The amount of acetyl groups is a molar fraction calculated by dividing the amount of ethylene groups to which acetyl groups are bonded by the total amount of ethylene groups in the main chain, expressed as a percentage. The amount of ethylene groups to which acetyl groups are bonded can be measured, for example, in accordance with JIS K6728 "Test Methods for Polyvinyl Butyral."

[0038] Polyvinyl acetal resins typically have acetal groups, hydroxyl groups, and acetyl groups in their side chains. To increase the glass transition temperature, the polyvinyl acetal resin may be an unmodified polyvinyl acetal resin that does not have any other functional groups in its side chains. Alternatively, the polyvinyl acetal resin may be a modified polyvinyl acetal resin that has a modifying group in its side chain other than an acetal group, a hydroxyl group, and an acetyl group. Examples of the modifying group include a carboxamido group (-CONHR), an acyl group other than an acetyl group (-COR), and a polyoxyalkylene group. R in each of the carboxamido group and the acyl group is a hydrocarbon group having 2 to 30 carbon atoms, preferably an alkyl group having 3 to 24 carbon atoms, and more preferably an alkyl group having 5 to 20 carbon atoms. Examples of the polyoxyalkylene group include a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group, and a group consisting of a copolymer of two or more types selected from oxyethylene, oxypropylene, and oxybutylene.

[0039] (Plasticizer) The thermoplastic resin sheet may contain a plasticizer as an additive in addition to the thermoplastic resin. By containing a plasticizer, the thermoplastic resin sheet becomes more flexible and has higher impact absorption properties.

[0040] 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. One type of plasticizer may be used alone, or two or more types may be used in combination. Among the above, organic ester plasticizers and organic ether-based plasticizers are preferred.

[0041] 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. Examples of glycols include monoalkylene glycols 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 the monobasic organic acid 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.

[0042] Specific examples of the monobasic organic acid ester 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-n-heptanoate. Examples of suitable alkyl acrylate copolymers include ethylene 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, and 1,2-butylene glycol di-2-ethylbutyrate.

[0043] 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, branched, or cyclic. 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 suitable. 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.

[0044] 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 a 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 monobasic organic acids include monobasic organic acids having 3 to 24 carbon atoms, preferably 6 to 18 carbon atoms. Specific examples of partial esters of a trihydric or higher alcohol and 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. Among the organic ester plasticizers listed above, triethylene glycol-di-2-ethylhexanoate (3GO) is particularly preferred.

[0045] Examples of organic phosphorus-based plasticizers include phosphate esters such as tributoxyethyl phosphate, isodecylphenyl phosphate, and triisopropyl phosphate. Examples of polyalkylene glycol-based plasticizers include polyethylene glycol, polypropylene glycol (PPG), poly(ethylene oxide / propylene oxide) block copolymers, poly(ethylene oxide / propylene oxide) random copolymers, and polytetramethylene glycol. Among these, polypropylene glycol is preferred.

[0046] The polyoxyalkylene ether plasticizer is an ether compound of a monohydric or polyhydric alcohol and a polyoxyalkylene. Specific examples of the polyoxyalkylene ether plasticizer 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.

[0047] 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, with triethylene glycol-di-2-ethylhexanoate (3GO) being more preferred.

[0048] When the thermoplastic resin sheet contains a plasticizer, the content of the plasticizer is not particularly limited, but is preferably 10 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the thermoplastic resin. When the content of the plasticizer is 10 parts by mass or more, the thermoplastic resin sheet becomes moderately flexible, and impact absorption can be further improved. On the other hand, when the content of the plasticizer is 100 parts by mass or less, separation of the plasticizer from the thermoplastic resin sheet is prevented. The content of the plasticizer is more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and 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.

[0049] 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.

[0050] (Other Additives) The thermoplastic resin sheet may contain other additives in addition to the above-mentioned plasticizers. Specific examples of the other additives include adhesion modifiers, moisture resistance improvers, light stabilizers, antioxidants, dispersants, ultraviolet absorbers, infrared absorbers, heat-shielding materials, pigments, dyes, fluorescent brighteners, crystal nucleating agents, antistatic agents, antiblocking agents, refractive index modifiers, and light scattering agents.

[0051] (Thickness) The thickness of the thermoplastic resin sheet is not particularly limited, but from the viewpoint of ensuring the impact absorption of image display devices and the like, it is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 380 μm or more, and is preferably 1000 μm or less, more preferably 760 μm or less.

[0052] (Shape) The thermoplastic resin sheet in the laminate of the present invention is preferably in the form of a film, from the viewpoint of being easily attached to each component constituting an image display device or the like. In this case, the thermoplastic resin sheet may be obtained, for example, by mixing a thermoplastic resin and various additives, if necessary, and molding the resulting resin composition by extrusion molding, press molding, or the like. The thermoplastic resin sheet may have a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, each layer may be molded by extrusion molding, press molding, or the like, and then laminated. For example, a method of co-extrusion using two or more extruders and attaching multi-layer 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.

[0053] Furthermore, the thermoplastic resin sheet in the laminate of the present invention is preferably used as an adhesive for bonding various components constituting an image display device or the like. Therefore, the thermoplastic resin sheet is preferably cut to a desired size suitable for bonding. The shape of the thermoplastic resin sheet is not particularly limited, but may be rectangular or circular. For example, in the case of a rectangular shape, the size of the thermoplastic resin sheet may be adjusted appropriately depending on the application, but may be, for example, approximately 50 to 400 mm in length and 50 to 400 mm in width, or may be 140 to 300 mm in length and 80 to 400 mm in width. In the case of a circular shape, the size of the thermoplastic resin sheet may be, for example, approximately 50 to 200 mm in radius.

[0054] <Applications> As described above, the laminate of the present invention can suppress blocking between thermoplastic resin sheets during storage. When in use, the thermoplastic resin sheets can be peeled (removed) one by one from the laminate. The individual thermoplastic resin sheets removed from the laminate are preferably used as interlayer fillers for bonding various components. That is, the laminate of the present invention is also a laminate comprising a separation layer and a thermoplastic resin sheet used as an interlayer filler. As described above, when the thermoplastic resin sheet contains a polyvinyl acetal resin, it exhibits excellent impact absorption and shatterproof properties. Furthermore, since it is cut to the desired size as needed, it also has excellent handleability and productivity. Below, an example will be described in which the thermoplastic resin sheet removed from the laminate of the present invention is used as an interlayer filler (an interlayer filler made of a thermoplastic resin sheet). The above interlayer filler is sometimes referred to as the interlayer filler of the present invention.

[0055] [Laminated Structure, Laminated Glass, Image Display Device] The interlayer filler of the present invention can be used to form a laminated structure comprising the interlayer filler and at least one transparent substrate. Examples of the transparent substrate include an organic material substrate and an inorganic material substrate.

[0056] Examples of organic material substrates include organic resin plates and resin films. Organic resin plates are also called organic glass plates. Examples of organic resin plates include, but are not limited to, polycarbonate plates, (meth)acrylic plates such as polymethyl methacrylate plates, polyester plates such as acrylonitrile-styrene copolymer plates, acrylonitrile-butadiene-styrene copolymer plates, and polyethylene terephthalate plates, and various organic glass plates such as 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. The organic resin plates may be subjected to appropriate surface treatments. Among the above, polycarbonate plates are preferred because of their excellent transparency and impact resistance, and (meth)acrylic plates are preferred because of their high transparency, weather resistance, and mechanical strength, with polycarbonate plates being more preferred. The thickness of the organic resin plate is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.4 mm or more, and is preferably 5.0 mm or less, more preferably 3.0 mm or less.

[0057] The resin film is not particularly limited, but examples thereof include polyester resin films such as (meth)acrylic resin film, polycarbonate film, polyethylene terephthalate (PET) film, and polyethylene naphthalate (PEN) film; polyolefin resin films such as polyethylene film and polypropylene film; cyclic polyolefin (COP) film, triacetyl cellulose (TAC) film, polyethersulfone (PES) resin film, and polyimide resin film. Furthermore, a surface layer such as a hard coat layer made of a (meth)acrylic resin may be provided on the surface of the resin film. The thickness of the resin film is not particularly limited, but is preferably 30 μm or more, more preferably 50 μm or more, and also preferably 500 μm or less, and more preferably 450 μm or less. While a relatively thick, low-flexibility, and generally unbendable material is referred to as an organic resin plate, a relatively thin, generally bendable material is generally referred to as a resin film, but these are not clearly distinguishable.

[0058] Examples of inorganic material substrates include inorganic glass plates. The inorganic glass plates are not particularly limited, but include various glass plates such as float glass, tempered glass, colored glass, polished glass, patterned glass, wired glass, lined glass, ultraviolet absorbing glass, infrared reflecting glass, infrared absorbing glass, and green glass. The inorganic glass may be subjected to surface treatment. The thickness of the inorganic glass is not particularly limited, but is preferably 0.1 mm or more, more preferably 1.0 mm or more, and is preferably 5.0 mm or less, more preferably 3.0 mm or less.

[0059] The organic material substrate or inorganic material substrate may be appropriately provided with an electrode, a sensor, or the like. The electrode is composed of a conductive layer laminated on each of the above substrates. A touch sensor may be laminated on each of the above substrates as a sensor to form a substrate with a touch sensor. The touch sensor is a sensor that detects touch input when a finger, a touch pen, or other object approaches or contacts the substrate, and is composed of a conductive layer laminated on the above substrate. When a finger, a touch pen, or other object approaches or contacts 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 particular limitation, and examples thereof include an indium tin oxide (ITO) conductive film, a tin oxide conductive film, a zinc oxide conductive film, and a polymer conductive film.

[0060] Among the above, the inorganic material substrate is preferably selected from the group consisting of an inorganic glass plate and an inorganic glass plate to which at least one of an electrode or a sensor is attached. The organic material substrate is preferably at least one selected from the group consisting of a polycarbonate plate, a (meth)acrylic plate, a PET film, a COP film, a polycarbonate film, and a film to which at least one of an electrode or a sensor is attached. Furthermore, an organic material substrate (particularly a film) on which a conductive layer such as an electrode or a sensor is laminated may have the above-mentioned hard coat layer formed on the surface opposite to the surface on which the conductive layer is provided.

[0061] The laminated structure is not particularly limited, but preferably has a multilayer structure of three or more layers, including a pair of transparent substrates selected from inorganic material substrates and organic material substrates, and an interlayer filler disposed between the pair of transparent substrates. In such a multilayer structure, the interlayer filler may be bonded to both of the pair of transparent substrates, for example, so that the pair of transparent substrates are joined via the interlayer filler.

[0062] The laminated structure may also have a structure in which another intermediate member is disposed between the pair of transparent substrates. In such a structure, an adhesive film may be disposed between each transparent substrate and the intermediate member, resulting in a multilayer structure of five or more layers. Here, the adhesive film may be adhered to each transparent substrate and the intermediate member, thereby bonding the transparent substrate and the intermediate member via the adhesive film. In the multilayer structure of five or more layers described above, the adhesive film between the transparent substrate and the intermediate member is a resin film, and at least one of them may be the interlayer filler of the present invention, but it is preferable that both be the interlayer filler of the present invention. The intermediate member may have at least one of the inorganic material substrate and the organic material substrate described above, and at least one of the inorganic material substrate and the organic material substrate may be disposed at the position where the interlayer filler of the present invention is adhered. In addition, a multilayer structure of five or more layers may have three or more transparent substrates, for example, arranged in the order of transparent substrate, transparent substrate, intermediate member, and transparent substrate, with an adhesive film disposed between each of these members. In this case, it is sufficient that one of the adhesive films is the interlayer filler of the present invention. Furthermore, the intermediate member may be a substrate with a touch sensor, as will be described later, but is not limited to this.

[0063] The laminated structure described above may constitute laminated glass, an image display device, a touch panel, or the like. In this case, the laminated glass has the interlayer filler of the present invention. The image display device has the interlayer filler of the present invention. Furthermore, the image display device may further have a cover glass and an image display panel in addition to the interlayer filler of the present invention. Furthermore, the touch panel has the interlayer filler of the present invention. Furthermore, the touch panel may further have a touch sensor, a cover glass, and an image display device. The touch panel is preferably an in-vehicle touch panel. The laminated structure described above is not limited to these.

[0064] 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, and is particularly preferably disposed below the windshield of the automobile in front of either the driver's seat or the passenger seat. In other words, the image display device is preferably disposed in a position where a conventional instrument panel would be disposed.

[0065] The laminated structure can be produced, for example, by preparing the interlayer filler of the present invention and compressing each component via the prepared interlayer filler. For example, it can be produced by stacking a transparent substrate, the interlayer filler of the present invention, and a transparent substrate in this order and compressing them together. Furthermore, when an intermediate component is provided, it can be produced, for example, by stacking a transparent substrate, an interlayer filler, an intermediate component, an interlayer filler, and a transparent substrate in this order and compressing them together.

[0066] 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.

[0067] (Adhesion Strength) The laminates prepared in each Example and Comparative Example were left at room temperature (23°C) for 6 hours. Then, a three-layer laminate, consisting of separation layer 1, thermoplastic resin sheet 1, and separation layer 2 laminated in this order, was removed from the bottom side of the laminate. The separation layer opposite the bottom side (i.e., the internal separation layer 2) was peeled from the three-layer laminate to prepare a two-layer laminate consisting of separation layer 1 and thermoplastic resin sheet 1. This was then cut into a 25 mm width to prepare a test specimen. The 180° peel strength of the test specimen was then measured. The 180° peel strength was measured using an Instron "5965 Model Universal Testing Machine" in accordance with the method of JIS K6854-2:1999. The surface of the test specimen facing the separation layer was fixed to a SUS plate using a double-sided adhesive tape (manufactured by Nitto Denko Corporation, product name: No. 501L). Next, a SUS plate was fixed to one side of the jig, and a thermoplastic resin sheet was fixed to the other side. The thermoplastic resin sheet 1 was pulled in the 180° direction at a pulling rate of 25 mm / min, and the arithmetic mean value of the peel strength (N / 25 mm) in the section from 25 mm to 125 mm from the start of the measurement was taken as the adhesive strength. The adhesive strength was measured twice, and the adhesive strength obtained from each measurement, which was the arithmetic mean value, was further averaged to determine the adhesive strength. The double-sided adhesive tape for fixing is not particularly limited, as long as it has an adhesive strength higher than the measured peel strength and does not peel at the interface between the SUS plate and the double-sided adhesive tape for fixing, or at the interface between the double-sided adhesive tape for fixing and the release layer after measurement.

[0068] (Tensile modulus) The tensile modulus of the separation layer was measured in accordance with JIS K 7161:2014. A dumbbell piece having a test section length L of 40 mm and a test section width W of 10 mm was punched out from the separation layer to prepare a measurement sample. This measurement sample was subjected to a tensile test using a tensile tester (Instron "5965 Type Universal Tester") at room temperature (23°C) and a tensile speed of 100 mm / min. The measurement was performed twice, and the arithmetic average value was used as the tensile modulus of each separation layer.

[0069] (Blocking) After production, the laminates produced in each of the Examples and Comparative Examples were allowed to stand at room temperature (25°C) for 6 hours. The laminates were then turned upside down. The thermoplastic resin sheet at the bottom when left standing was grasped to check whether it could be peeled off, and the results were evaluated based on the following criteria: A: The thermoplastic resin sheet at the bottom when left standing could be peeled off. C: The thermoplastic resin sheet at the bottom when left standing could not be peeled off.

[0070] (Ease of Holding) For the laminates prepared in each Example and Comparative Example, a three-layer laminate was removed from the top of the laminate, in which a separation layer (upper side) / a thermoplastic resin sheet / a separation layer (lower side) were stacked in this order. Then, the upper separation layer (i.e., the separation layer located at the top) was peeled off from the three-layer laminate to prepare a two-layer laminate consisting of a thermoplastic resin sheet and a separation layer (lower side). After removing the two-layer laminate, the laminates according to each Example and Comparative Example were repeatedly removed to further remove two-layer laminates consisting of a thermoplastic resin sheet on the top surface / a separation layer (lower side). Ten workers were asked to grasp and carry these two-layer laminates by the separation layer (lower side), and the ease of holding was evaluated according to the following criteria. A: 9 or more people out of 10 did not touch the thermoplastic resin sheet during transportation work. B: 6 or more but less than 9 people out of 10 did not touch the thermoplastic resin sheet during transportation work. C: 5 or more people out of 10 touched the thermoplastic resin sheet during transportation work.

[0071] (Firmness) From the laminates produced in each Example and Comparative Example, a three-layer laminate in which separation layer 1 / thermoplastic resin sheet 1 / separation layer 2 were laminated in this order was taken out from the top side of the laminate. Then, the topmost separation layer (i.e., separation layer 1 located at the top) was peeled off from the three-layer laminate to produce a two-layer laminate consisting of thermoplastic resin sheet 1 and separation layer 2. This two-layer laminate was placed on a horizontal surface with separation layer 2 facing downward. Next, both ends in the longitudinal direction (lateral direction) were lifted and lifted while being moved 40 mm toward the center. The state of the two-layer laminate at this time was observed, and the stiffness was evaluated according to the following criteria. A: No lifting occurs between the thermoplastic resin sheet and the separation layer. C: Lifting occurs between the thermoplastic resin sheet and the separation layer.

[0072] The following thermoplastic resin sheets and separation layers were used in the examples and comparative examples. <Thermoplastic Resin Sheet> PVB Film 1: 1800 ml of ion-exchanged water and 200 g of polyvinyl alcohol (average degree of polymerization 1700, degree of saponification 99 mol%) were placed in a reactor equipped with a stirrer and heated to dissolve while stirring, yielding a polyvinyl alcohol solution. Next, 30% hydrochloric acid was added as a catalyst to this solution to a hydrochloric acid concentration of 0.2% by mass. The temperature was then adjusted to 15°C, and n-butylaldehyde was added with stirring to a concentration of 10 mol%. Subsequently, n-butylaldehyde was added to a concentration of 60 mol%, resulting in the precipitation of white particulate polyvinyl butyral resin. Ten minutes after precipitation, 30% hydrochloric acid was added to a hydrochloric acid concentration of 1.8% by mass. The mixture was then heated to 53°C and aged for 2 hours at each aging temperature. The solution was then cooled and neutralized, and the polyvinyl butyral resin was washed with water and dried to obtain polyvinyl butyral resin 1 (hydroxyl group content: 30.8 mol%, degree of acetalization: 68.4 mol%, degree of acetylation: 0.8 mol%). 100 parts by mass of the obtained polyvinyl butyral resin (PVB) was kneaded and extruded with 35 parts by mass of plasticizer (triethylene glycol-di-2-ethylhexanoate: 3GO) using an extruder to produce a polyvinyl butyral film (PVB film 1) with a thickness of 380 μm. The produced polyvinyl butyral film was cut into a rectangular shape measuring 215 mm in length and 300 mm in width. PVB film 2: A polyvinyl butyral film was obtained in the same manner as PVB film 1, except that the thickness was 760 μm. The obtained polyvinyl butyral film was cut into a rectangular shape measuring 215 mm in length and 300 mm in width.

[0073] <Separation layer> PET film 1: Polyethylene terephthalate film, "Lumirror" manufactured by Toray Industries, Inc., biaxially oriented film, thickness 100 μm. Cut into a rectangle of 240 mm length and 330 mm width. PET film 2: Polyethylene terephthalate film, "Lumirror" manufactured by Toray Industries, Inc., biaxially oriented film, thickness 100 μm. Cut into a rectangle of 215 mm length and 270 mm width. PET film 3: Polyethylene terephthalate film, "Lumirror" manufactured by Toray Industries, Inc., biaxially oriented film, thickness 100 μm. Cut into a rectangle of 240 mm length and 315 mm width. PE film: Polyethylene film, "Ube Poly Sheet" manufactured by Ube Film Co., Ltd., thickness 100 μm. Cut into a rectangle of 240 mm length and 330 mm width. PP film: Polypropylene film, "Clear Holder Thin" manufactured by King Jim Co., Ltd., thickness 100 μm. It was cut into a rectangular shape measuring 240 mm in length and 330 mm in width.

[0074] [Example 1] Separation layers (PET film 1) and thermoplastic resin sheets (PVB film 1) were alternately laminated so that their centers overlapped, to obtain a laminate. The laminate consisted of 51 separation layers and 50 thermoplastic resin sheets, with both the top and bottom being separation layers. The evaluation results are shown in Table 1.

[0075] [Example 2] Separation layers (PET film 1) and thermoplastic resin sheets (PVB film 2) were alternately laminated so that their centers overlapped, to obtain a laminate. The laminate consisted of 51 separation layers and 50 thermoplastic resin sheets, with both the top and bottom being separation layers. The evaluation results are shown in Table 1.

[0076] [Example 3] Separation layers (PE films) and thermoplastic resin sheets (PVB films 1) were alternately laminated so that their centers overlapped, to obtain a laminate. The laminate consisted of 51 separation layers and 50 thermoplastic resin sheets, with both the top and bottom being separation layers. The evaluation results are shown in Table 1.

[0077] [Example 4] Separation layers (PP films) and thermoplastic resin sheets (PVB films 1) were alternately laminated so that their centers overlapped, to obtain a laminate. The laminate consisted of 51 separation layers and 50 thermoplastic resin sheets, with both the top and bottom being separation layers. The evaluation results are shown in Table 1.

[0078] [Comparative Example 1] 101 layers of thermoplastic resin sheets (PVB film 1) were laminated so that their centers overlapped to obtain a laminate. This laminate consisted of only thermoplastic resin sheets, and no separation layer was used. The evaluation results are shown in Table 1.

[0079] [Comparative Example 2] Separation layers (PET film 2) and thermoplastic resin sheets (PVB film 1) were alternately laminated so that their centers overlapped, to obtain a laminate. The laminate consisted of 51 separation layers and 50 thermoplastic resin sheets, with both the top and bottom being separation layers. The evaluation results are shown in Table 1.

[0080] [Example 5] Separation layers (PET film 3) and thermoplastic resin sheets (PVB film 1) were alternately laminated so that their centers overlapped, to obtain a laminate. The laminate consisted of 51 separation layers and 50 thermoplastic resin sheets, with both the top and bottom being separation layers. The evaluation results are shown in Table 1.

[0081]

[0082] The laminates of Examples 1 to 5 are laminates of the present invention in which the projected area of ​​the separation layer is equal to or greater than the projected area of ​​the thermoplastic resin sheet, and blocking of the thermoplastic resin sheet was suppressed. Among these, the laminates of Examples 1 to 4, in which the projected area of ​​the separation layer is 1.2 times or more the projected area of ​​the thermoplastic resin sheet, were also excellent in ease of holding. Furthermore, the laminates of Examples 1, 2, and 5, in which the tensile modulus of the separation layer is 2000 MPa or more and 5000 MPa or less, are less likely to bend, and the thermoplastic resin sheet does not slip off, thereby suppressing the occurrence of wrinkles in the thermoplastic resin sheet. In contrast, the laminate of Comparative Example 1 did not use a separation layer, and blocking of the thermoplastic resin sheet occurred. Furthermore, the laminate of Comparative Example 2, in which the projected area of ​​the separation layer is smaller than the projected area of ​​the thermoplastic resin sheet, caused blocking of the thermoplastic resin sheet.

[0083] 10, 20, 30, 40, 50 Laminate 11 Separation layer 12 Thermoplastic resin sheet 13 Support layer

Claims

1. A laminate comprising a thermoplastic resin sheet and a spacing layer, wherein the projected area of ​​the spacing layer is equal to or greater than the projected area of ​​the thermoplastic resin sheet.

2. The laminate of claim 1, wherein the spacing layer is in the form of a film.

3. The laminate according to claim 1 or 2, wherein the spacing layer has a flat portion and a protruding portion.

4. The laminate according to claim 1 or 2, wherein the adhesive strength between the thermoplastic resin sheet and the separation layer is 0.003 N / 25 mm or more and 0.02 N / 25 mm or less.

5. The laminate according to claim 1 or 2, wherein the tensile modulus of the spacing layer is 2000 MPa or more and 5000 MPa or less.

6. A laminate according to claim 1 or 2, wherein the spacing layer is flat.

7. A laminate according to claim 1 or 2, wherein the area of ​​the surface of the separation layer that contacts the thermoplastic resin sheet is equal to or greater than the area of ​​the surface of the thermoplastic resin sheet that contacts the separation layer.

8. A laminate according to claim 1 or 2, wherein the projected area of ​​the spacing layer is 1.1 times or more and 2 times or less the projected area of ​​the thermoplastic resin sheet.

9. The laminate according to claim 1 or 2, wherein the center of the thermoplastic resin sheet and the center of the spacing layer coincide with each other.

10. The laminate according to claim 1 or 2, wherein the thermoplastic resin sheet contains a polyvinyl acetal resin.

11. The laminate according to claim 1 or 2, wherein the thickness of the thermoplastic resin sheet is 100 μm or more and 1000 μm or less.

12. The laminate according to claim 1 or 2, wherein the thermoplastic resin sheet is an interlayer filler.

13. The laminate according to claim 1 or 2, wherein the thermoplastic resin sheets and the spacing layers are alternately laminated.

14. The laminate according to claim 1 or 2, further comprising a support layer on at least one of the upper and lower ends.

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