Laminate

Abstract

This laminate comprises an adhesive film and a first peelable substrate provided on one surface of the adhesive film. When the peel strength between the first peelable substrate and the adhesive film is noted as A (N / 25 mm) and the peeling strength between the adhesive film and a glass plate that is attached to the surface of the adhesive film opposite to the surface in contact with the first peelable substrate is noted as B (N / 25 mm), the peel strength ratio (A / B) is 4 or more. The present invention can provide a laminate having excellent reworkability.

Description

Laminate

[0001] The present invention relates to a laminate used as an interlayer film for laminated glass, an optically transparent adhesive for displays, and the like.

[0002] Conventionally, laminated glass, which is formed by interposing an interlayer film between two glass sheets and integrating them, has been widely known. The interlayer film is often formed from plasticized polyvinyl acetal, which is a polyvinyl acetal resin blended with a plasticizer. Laminated glass is safe because it hardly shatters glass fragments even if it is broken by external impact, and is therefore widely used as window glass in vehicles such as automobiles, aircraft, buildings, etc.

[0003] Laminated glass is generally produced by arranging two glass plates with an interlayer film, and after a preliminary degassing process, heating and pressurizing the glass and the interlayer film in an autoclave (ACV) process at a temperature of about 130°C to 140°C and a pressure of about 1.3 MPa.

[0004] In recent years, there has been a demand for laminated glass incorporating a light-control film and displays with reduced glass shatter resistance. When incorporating a light-control film into laminated glass, it is known that an interlayer film is disposed between the light-control film and each glass plate, and the two glass plates and the light-control film are integrated via the interlayer film (see, for example, Patent Document 1). In addition, in display applications, an optically transparent adhesive (OCA) is sometimes used to bond various components such as a cover glass to an image display panel, and it has been considered to use an adhesive film made of a polyvinyl acetal resin or the like for the optically transparent adhesive, similar to the interlayer film.

[0005] International Publication No. 2019 / 066042

[0006] In recent years, there has been a demand for cut sheets of interlayer films. When stacking cut sheets of multiple interlayer films, it is necessary to provide interleaving sheets between the cut sheets to prevent adhesion between the cut sheets. By providing a release substrate on both sides of the interlayer film, adhesion between the cut sheets can be prevented without providing interleaving sheets between the cut sheets. In this case, after peeling off the release substrate on one side of the cut sheet, the release surface of the cut sheet is temporarily adhered to an adherend while the release substrate on the other side of the cut sheet remains attached to the cut sheet. At this time, to correct misalignment of the cut sheet, the cut sheet temporarily adhered to the adherend may be peeled off from the adherend and temporarily re-adhered to the adherend, i.e., reworking the cut sheet. In this case, if the release substrate on the other side of the cut sheet peels off, the release substrate of the cut sheet may lift or the interlayer film of the cut sheet may wrinkle. If the release substrate lifts or the interlayer film wrinkles on the cut sheet, it becomes difficult to reuse the cut sheet. Therefore, an object of the present invention is to provide a laminate with excellent reworkability.

[0007] As a result of extensive research, the present inventors have found that the above problems can be solved by setting the peel strength ratio of the peel strength when peeling the adhesive film from the releasable substrate to the peel strength when peeling the adhesive film from the glass plate within a predetermined range, and have completed the present invention as described below. That is, the present invention provides the following [1] to

[15] .

[0008] [1] A laminate comprising an adhesive film and a first releasable substrate provided on one side of the adhesive film, wherein, where A (N / 25 mm) is the peel strength between the first releasable substrate and the adhesive film and B (N / 25 mm) is the peel strength between the adhesive film and a glass plate when the adhesive film is attached to the side of the adhesive film opposite to the side in contact with the first releasable substrate, the peel strength ratio (A / B) is 4 or more. [2] The laminate according to [1] above, wherein the peel strength A is 0.5 N / 25 mm or more and 10 N / 25 mm or less. [3] The laminate according to [1] or [2] above, wherein the peel strength B is 0.1 N / 25 mm or more and 2.5 N / 25 mm or less. [4] The laminate according to any one of [1] to [3] above, wherein the adhesive film has a storage modulus (G') at 25°C of 3 MPa or more and 11.3 MPa or less. [5] The laminate according to any one of [1] to [4] above, wherein the adhesive film is made of a thermoplastic resin composition containing a thermoplastic resin. [6] The laminate according to any one of [1] to [5] above, wherein the root mean square slope Sdq of the release surface of the adhesive film after peeling off the first release substrate is 3 or more and 20 or less. [7] The laminate according to any one of [1] to [6] above, wherein the surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate is 3 μm or more and 10 μm or less. [8] The laminate according to any one of [1] to [7] above, wherein the first release substrate is at least one substrate selected from the group consisting of release film, release paper, mesh material, metal, and prepreg, and the resin constituting the release film is a polyester resin, a polyolefin resin, a polyimide resin, a fluororesin such as tetrafluoroethylene, a silicone resin, a liquid crystal polymer, a polysulfone resin, cellulose acetate, a polyamide resin, a polyether ether ketone resin, a polyether ketone ketone resin, a modified polyphenylene ether, a polyphenylene sulfide resin, a polycarbonate resin, or a polybenzimidazole resin. [9] The laminate according to any one of [1] to [8] above, wherein, in a plan view, at least a portion of the periphery of the first release substrate extends outward relative to the periphery of the adhesive film.

[10] The laminate according to any one of [1] to [9] above, further comprising a second release substrate provided on the other side of the adhesive film.

[11] The laminate according to

[10] above, wherein, when the peel strength between the second release substrate and the adhesive film is C (N / 25 mm), the peel strength C is smaller than the peel strength A.

[12] The laminate according to

[10] above, wherein the second release substrate is at least one substrate selected from the group consisting of release films, release papers, mesh materials, metals, and prepregs, and the resin constituting the release film is polyester resin, polyolefin resin, polyimide resin, fluororesin such as tetrafluoroethylene, silicone resin, liquid crystal polymer, polysulfone resin, cellulose acetate, polyamide resin, polyether ether ketone resin, polyether ketone ketone resin, modified polyphenylene ether, polyphenylene sulfide resin, polycarbonate resin, or polybenzimidazole resin.

[13] The laminate according to any one of

[10] to

[12] above, wherein, in a plan view, at least a part of the periphery of the second release substrate extends outward relative to the periphery of the adhesive film.

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

[13] above, wherein the surface roughness Rzjis of the surface of the adhesive film opposite to the surface in contact with the first release substrate is 3 μm or more and 10 μm or less.

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

[14] above, wherein the visible light transmittance of the adhesive film after all release substrates have been peeled from the laminate is less than 90%.

[0009] According to the present invention, a laminate having excellent reworkability can be provided.

[0010] Fig. 1 is a diagram illustrating one embodiment of a method for producing a laminate of the present invention. Fig. 2 is a diagram illustrating one embodiment of a method for producing a laminate of the present invention. Fig. 3 is a diagram illustrating an example of a tan δ-temperature curve.

[0011] <Laminate> The laminate of the present invention comprises an adhesive film and a first releasable substrate provided on one side of the adhesive film, and when the peel strength between the first releasable substrate and the adhesive film is A (N / 25 mm) and the peel strength between the adhesive film and a glass plate when a glass plate is attached to the side of the adhesive film opposite to the side in contact with the first releasable substrate is B (N / 25 mm), the peel strength ratio (A / B) is 4 or more. This makes it possible to suppress peeling of the releasable substrate from the adhesive film when reworking the laminate attached to an adherend.

[0012] [Peel Strength Ratio (A / B)] As described above, the laminate of the present invention has a peel strength ratio (A / B) of 4 or more. If the peel strength ratio (A / B) is less than 4, the first release substrate may peel from the adhesive film during rework of the laminate attached to an adherend. From this perspective, the peel strength ratio (A / B) is preferably 4.5 or more, more preferably 5.0 or more, even more preferably 6.0 or more, and even more preferably 7.0 or more. The upper limit of the range of the peel strength ratio (A / B) is not particularly limited, but is usually 30, preferably 25, and more preferably 20. The peel strength can be measured by the method described in the Examples below. The peel strength ratio (A / B) can also be adjusted by forming an uneven shape on the surface of the first release substrate to improve the peel strength between the first release substrate and the adhesive film. Furthermore, when the first releasable substrate has an adhesion adjusting layer described below, the adhesion can also be adjusted by the type of resin constituting the adhesion adjusting layer and the thickness of the adhesion adjusting layer.

[0013] The peel strength A is preferably 0.5 N / 25 mm or more and 10 N / 25 mm or less. When the peel strength A is 0.5 N / 25 mm or more, peeling of the first release substrate from the adhesive film can be further suppressed when reworking the laminate attached to the adherend. When the peel strength A is 10 N / 25 mm or less, the laminate is fully adhered to the adherend, and after the laminate is completely adhered to the adherend, it is easy to peel the first release substrate from the laminate. From this viewpoint, the peel strength A is more preferably 1.0 N / 25 mm or more and 6 N / 25 mm or less, even more preferably 2.0 N / 25 mm or more and 5.7 N / 25 mm or less, and even more preferably 2.3 N / 25 mm or more and 5.5 N / 25 mm or less. The peel strength A when peeling the first release substrate from the adhesive film can be adjusted by the uneven shape of the surface of the first release substrate, the type of resin of the first release substrate, etc. Furthermore, when the first releasable substrate has an adhesive strength adjustment layer described later, the peel strength A can be adjusted by the type of resin constituting the adhesive strength adjustment layer and the thickness of the adhesive strength adjustment layer. Furthermore, it can also be adjusted by adjusting the temperature of the releasable substrate in the laminating mechanism 15 described later. For example, in the configuration shown in FIG. 2 described later, the peel strength A can be increased by increasing the temperature of the first roll 35.

[0014] The peel strength B is preferably 0.1 N / 25 mm or more and 2.5 N / 25 mm or less. When the peel strength B is 0.1 N / 25 mm or more, it becomes easier to temporarily adhere the laminate to the adherend. When the peel strength B is 2.5 N / 25 mm or less, it becomes easier to rework the laminate. From this viewpoint, the peel strength A is more preferably 0.2 N / 25 mm or more and 1.2 N / 25 mm or less, even more preferably 0.25 N / 25 mm or more and 1.0 N / 25 mm or less, and even more preferably 0.27 N / 25 mm or more and 0.92 N / 25 mm or less. The peel strength B when peeling the adhesive film from the glass plate can be adjusted by the uneven shape of the surface of the adhesive film, the type of resin constituting the adhesive film, the thickness of the adhesive film, etc.

[0015] [First release substrate] The first release substrate is not particularly limited as long as it can be released from the adhesive film. Examples of the first release substrate include release film, release paper, mesh material, metal, prepreg, etc. These release substrates can be used alone or in combination of two or more. For example, a release film laminated with a mesh material or metal can also be used.

[0016] The release film may be any known resin film, and examples of the resin constituting the release film include, but are not limited to, polyester resin, polyolefin resin, polyimide resin, fluororesin such as tetrafluoroethylene, silicone resin, liquid crystal polymer, polysulfone resin, cellulose acetate, polyamide resin, polyether ether ketone resin, and polyether ketone ketone resin.

[0017] Examples of polyester resins include polyethylene terephthalate resin (PET), polyethylene terephthalate glycol resin (PETG), polybutylene naphthalate resin (PBN), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), polyhexamethylene terephthalate resin (PHT), copolymerized polyethylene terephthalate-isophthalate resin (PET / PEI), polyethylene naphthalate resin (PEN), and polylactic acid resin. Preferred polyester resins include PET, PEN, and PBN, with PET being more preferred. Examples of polyolefin resins include polyethylene resins such as ultra-high molecular weight polyethylene, high-density polyethylene, low-density polyethylene, and linear low-density polyethylene, polypropylene resin, polymethylpentene resin (PMP), and cyclic olefin resin (COP). Among these, polypropylene resin and polymethylpentene resin (PMP) are more preferred. Examples of fluororesins include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE or CTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy fluororesin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and tetrafluoroethylene-perfluoroalkoxyethylene copolymer. Among these, polytetrafluoroethylene is more preferred. Examples of polysulfone resins include polysulfone (PSU), polyphenylsulfone (PPSU), and polyethersulfone (PES). In addition to these resins, modified polyphenylene ether, polyphenylene sulfide resin, polycarbonate resin, polybenzimidazole resin, and the like can also be suitably used. Of these, polyolefin resins and polyester resins are preferred, and among these, PET, polyethylene resins, polypropylene resins (PP), and polymethylpentene resins are preferred, with PET and PP being more preferred, and PET being even more preferred.Therefore, the film substrate constituting the release film is preferably a polyolefin resin film or a polyester resin film, more preferably a PET film or a PP film, and even more preferably a PET film.

[0018] These resins may be used alone or in combination of two or more. The film substrate may be composed of a single layer or may have a multilayer structure of two or more layers. When it has a multilayer structure of two or more layers, the resins constituting each layer may be the same or different. The resin film may be a non-stretched film or a stretched film. For example, a stretched PP film is preferred from the viewpoint of heat resistance, and a biaxially stretched PP film is more preferred.

[0019] The release film preferably has an uneven surface in contact with the adhesive film, which increases the contact area between the release film and the adhesive film, thereby increasing the peel strength of the release film and making it easier to achieve a peel strength ratio (A / B) of 4 or more.

[0020] The surface shape of the release film having an uneven shape is not particularly limited, and may be a configuration in which protrusions and grooves are formed and the protrusions and grooves are regularly arranged, or a shape in which a large number of random recesses are formed. Among these, a shape in which a large number of random recesses are formed is preferred for the surface shape of the release film. This increases the contact area between the adhesive film and the release film, making it easier to increase the peel strength of the release film. Examples of methods for forming unevenness on the surface of the release film include an embossing roll method, a calendar roll method, a profile extrusion method, and a melt fracture method. Among these, embossing by the embossing roll method is preferred. In the embossing roll method, the surface of a roll used for embossing is formed with a blasting agent, and then the iron roll is vertically ground to produce an embossing roll for forming random recesses on the surface of the release film, and this embossing roll may be used.

[0021] The release film may have an adhesive strength adjusting layer, which makes it easier to adjust the peel strength when peeling the first releasable substrate from the adhesive film. The adhesive strength adjusting layer is preferably provided on the surface facing the adhesive film.

[0022] The adhesive strength adjusting layer may be a release layer that improves the releasability when peeling off the adhesive film. When the adhesive strength adjusting layer is a release layer, examples of the resin constituting the release layer include silicone resin, fluororesin, melamine resin, epoxy resin, phenolic resin, and acrylic resin. These resins can be used alone or in combination of two or more. Among these, silicone resins are preferred.

[0023] The adhesion adjusting layer may be formed from a primer of a urethane resin or a polyethylene resin, in addition to being formed from the above-mentioned resins. Among these, a urethane resin is preferred. The urethane resin primer increases the polarity of the surface of the release film, thereby improving the adhesive strength of the surface of the release film. The adhesion adjusting layer may also be formed by corona treatment or plasma treatment of the surface of the release film. By corona treatment or plasma treatment of the surface of the release film, functional groups are generated on the surface of the release film, which increases the polarity of the surface of the release film and allows the adhesive strength of the surface of the release film to be adjusted.

[0024] The thickness of the adhesion adjusting layer is preferably 0.01 μm or more and 20 μm or less, more preferably 0.05 μm or more and 10 μm or less, and even more preferably 0.08 μm or more and 5 μm or less.

[0025] The release paper may be a known release paper, preferably one having a release layer provided on at least one surface of the paper substrate. The release layer may be provided on the surface of the adhesive film. The release layer may be formed from a release agent, which may be a silicone-based release agent or a non-silicone-based release agent. In the case of a silicone-based release agent, a silicone resin may be used as the resin in the release agent. In the case of a silicone-based release agent, a silicone resin may be used as the resin in the release agent. In addition, examples of resins used in non-silicone-based release agents include fluororesins, melamine resins, epoxy resins, phenolic resins, and acrylic resins. In addition, the paper substrate used for the release paper may be one that has been treated to prevent the release agent from penetrating the base paper, such as glassine paper, seal-coated paper, PE-laminated paper, or PET-laminated paper.

[0026] Examples of mesh materials include resin mesh and metal mesh. Resin meshes may be woven or knitted fabrics made of resin fibers, or nonwoven fabrics. The resins used in the resin mesh may be any of the resins listed above for use in the release film. Examples of metal meshes include aluminum mesh, stainless steel mesh, and copper mesh. Examples of metals include metal foils such as aluminum foil, stainless steel foil, and copper foil, as well as metal plates. Metal plates may be thin and flexible, and examples include aluminum plates, stainless steel plates, and copper plates. Examples of pre-polymers include those obtained by impregnating reinforcing fibers such as glass fibers and carbon fibers with matrix resins such as epoxy resins, modified polyphenylene ether resins, polyimide resins, and polybenzoxazole resins.

[0027] The first release substrate is more preferably a release film from the viewpoint of ease of handling and further reduction in the thermal shrinkage rate.

[0028] The thickness of the first release substrate is preferably 10 μm or more and 200 μm or less. When the thickness of the first release substrate is 10 μm or more and 200 μm or less, the handling of the laminate becomes easier. From this viewpoint, the thickness of the first release substrate is more preferably 20 μm or more and 150 μm or less, and even more preferably 30 μm or more and 130 μm or less.

[0029] In a plan view, the outer periphery of the first release substrate may coincide with the outer periphery of the adhesive film, or at least a portion of the outer periphery of the first release substrate may extend outward relative to the outer periphery of the adhesive film. The portion of the first release substrate that extends outward relative to the outer periphery of the adhesive film can be grasped to easily peel the laminate temporarily adhered to the adherend from the adherend, facilitating rework, so it is preferable that at least a portion of the periphery extends outward relative to the outer periphery of the adhesive film. Furthermore, the first release substrate can be easily peeled from a laminate completely adhered to the adherend. From the viewpoint of ease of gripping the extending portion of the first release substrate, the length of the extending portion of the first release substrate in the extending direction is preferably 5 mm or more and 100 mm or less, more preferably 10 mm or more and 50 mm or less, and even more preferably 15 mm or more and 40 mm or less. It is also possible to make at least the length in the longitudinal direction of the first release substrate longer than the length in the longitudinal direction of the adhesive film, so that the portion extending from the adhesive film is provided on the first release substrate.

[0030] [Adhesive film] The adhesive film is not particularly limited as long as it is a film having adhesive properties. Examples of adhesive films include those made of a thermosetting resin composition containing a thermosetting resin, and those made of a thermoplastic resin composition containing a thermoplastic resin. The adhesive film is preferably made of a thermoplastic resin composition containing a thermoplastic resin.

[0031] (Thermoplastic Resin) Examples of the thermoplastic resin contained in the thermoplastic resin composition 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 of two or more. Among these thermoplastic resins, ethylene-vinyl acetate copolymer resins (EVA) and polyvinyl acetal resins are preferred from the viewpoint of adhesiveness, and polyvinyl acetal resins are more preferred from the viewpoint of adhesiveness to glass, with polyvinyl butyral resins (PVB) being even more preferred. The thermoplastic resins used in the thermoplastic resin composition may be used alone or in combination of two or more.

[0032] (Polyvinyl acetal resin) The polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition 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 a modifying group on a side chain. The polyvinyl acetal resin is obtained by acetalizing polyvinyl alcohol with an aldehyde and, if necessary, reacting it with a modifying agent. In addition, to obtain the modified polyvinyl acetal resin, modified polyvinyl alcohol may be used as the raw material polyvinyl alcohol.

[0033] <Degree of Acetalization> The degree of acetalization of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition 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 number of hydroxyl groups in the polyvinyl acetal resin is reduced, and the adhesive film has sufficient flexibility. When the degree of acetalization of the polyvinyl acetal resin is 75 mol% or less, the adhesion to an adherend such as inorganic glass is improved. From this viewpoint, 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. Note that 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.

[0034] The degree of acetalization is a molar fraction obtained 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, and dividing the result by the total amount of ethylene groups in the main chain, and the percentage is expressed as the molar fraction. The degree of acetalization (degree of butyralization) may be calculated from the results of measurements made, for example, according to JIS K6728 "Testing Methods for Polyvinyl Butyral."

[0035] <Weight Average Molecular Weight> The weight average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition 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 composition is more preferably 230,000 or more, even more preferably 240,000 or more, and even more preferably 260,000 or more. Furthermore, the weight average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition is preferably 310,000 or less. When the weight average molecular weight (Mw) of the polyvinyl acetal resin is 310,000 or less, the adhesive film has sufficient flexibility. Furthermore, when the adherend is glass, shattering of the glass can be more effectively suppressed. From this perspective, the weight average molecular weight (Mw) of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition is more preferably 305,000 or less, even more preferably 300,000 or less, and even more preferably 290,000 or less. The weight average molecular weight (Mw) of the polyvinyl acetal resin is measured by gel permeation chromatography. The weight average molecular weight can be measured by the following measurement method. A measurement sample is dissolved to a concentration of 0.05% by mass in an N-methyl-2-pyrrolidone solution to which lithium bromide has been added so that the concentration becomes 10 mM, and the solution is filtered using a syringe filter (Millex-LH 0.45 μm, manufactured by Merck). After filtration, measurement is performed using gel permeation chromatography (e2690, manufactured by Waters), and the molecular weight is calculated using a molecular weight calibration curve prepared using monodisperse polystyrene standard samples. The column used is Shodex GPC KF-806L (Showa Denko KK), and the eluent used is an N-methyl-2-pyrrolidone solution containing lithium bromide added to a concentration of 10 mM.

[0036] <Aldehyde> The polyvinyl acetal resin used as the thermoplastic resin in the thermoplastic resin composition 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 preferably 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 polyvinyl butyral resin (PVB).

[0037] <Polyvinyl Alcohol (PVA)> Polyvinyl alcohol (PVA), 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%. 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. When the average degree of polymerization is above the lower limit, the penetration resistance of laminated glass is improved when used in laminated glass. Furthermore, 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 "Test Method for Polyvinyl Alcohol." Furthermore, 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.

[0038] 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 produce the polyvinyl acetal resin using a mixture of two or more polyvinyl alcohols as the raw material by the production method described below. When two or more polyvinyl alcohols are used, it is preferable to use, for example, a first polyvinyl alcohol having an average degree of polymerization of 1500 or more and a second polyvinyl alcohol having an average degree of polymerization of 1000 or less. By using two or more polyvinyl alcohols having different average degrees of polymerization, the flexibility of the adhesive film can be improved. The average degree of polymerization of the first polyvinyl alcohol is preferably 1500 or more and 3500 or less, more preferably 1600 or more and 2500 or less, and even more preferably 1600 or more and 2000 or less. The average degree of polymerization of the second polyvinyl alcohol is preferably 200 or more and 1000 or less, more preferably 300 or more and 900 or less, and even more preferably 400 or more and 700 or less. When the first and second polyvinyl alcohols are used, the blending ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is not particularly limited, but the blending amount of the second polyvinyl alcohol relative to the total amount of the first and second polyvinyl alcohols is preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 40% by mass or less, even more preferably 3% by mass or more and 30% by mass or less, and still more preferably 5% by mass or more and 15% by mass or less.

[0039] <Hydroxyl Group Amount> The hydroxyl group amount of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition is preferably 15 mol% or more and preferably 38 mol% or less. By setting the hydroxyl group amount to 15 mol% or more, adhesion to the adherend is likely to be good. Furthermore, by setting the hydroxyl group amount to 38 mol% or less, flexibility is easily ensured, and the impact absorption of the thermoplastic resin composition can be further improved. The hydroxyl group amount is more preferably 20 mol% or more, and even more preferably 25 mol% or more. Furthermore, the hydroxyl group amount 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 hydroxyl group amount 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% 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 having hydroxyl groups by the total amount of ethylene groups in the main chain, and is expressed as a percentage. The amount of ethylene groups having hydroxyl groups can be measured, for example, in accordance with JIS K6728 "Testing Methods for Polyvinyl Butyral."

[0040] <Degree of Acetylation> The degree of acetylation of the polyvinyl acetal resin used as the thermoplastic resin of the thermoplastic resin composition 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 degree of acetylation is below the upper limit, the moisture resistance of the thermoplastic resin composition is improved. Furthermore, the degree of acetylation 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 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."

[0041] <Modified Polyvinyl Acetal Resin> The polyvinyl acetal resin used as the thermoplastic resin in the thermoplastic resin composition may be 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 the side chain. Examples of the modifying group include those having a polyalkylene oxide structure on the side chain, and those having an acetal group or an alkyl group other than an acetyl group (e.g., having about 2 to 30 carbon atoms) on the 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 refers to the ratio of functional groups to all vinyl monomer units constituting the polyvinyl acetal resin.

[0042] (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.

[0043] 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 polyvinyl alcohols are used in combination (for example, when two or more polyvinyl alcohols with different molecular weights are used), the two or more polyvinyl alcohols may be mixed with the aldehyde.

[0044] The aging step is not particularly limited, but may involve, for example, adding a catalyst such as an acid catalyst to the mixture (reaction mixture) obtained by the mixing step, heating to the 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 to obtain a polyvinyl acetal resin. After maintaining the reaction mixture at the aging temperature for a certain period of time, the reaction mixture may be appropriately cooled and neutralized, and then washed with water, dried, or the like, as necessary.

[0045] 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, preferably about 1% by mass or more and 2.5% by mass or less.

[0046] The aging temperature in the aging step may be relatively low, for example, from 30° C. to 68° C., preferably from 30° C. to 65° C., more preferably from 35° C. to 60° C., and even more preferably from 40° C. to 58° C. The time for which the aging temperature is maintained (aging time) may be longer than a certain time, for example, from 75 minutes to 180 minutes, preferably from 90 minutes to 150 minutes, and more preferably from 100 minutes to 140° C.

[0047] (Ethylene-vinyl acetate copolymer resin (EVA)) The ethylene-vinyl acetate copolymer resin may be a non-crosslinked ethylene-vinyl acetate copolymer resin or a high-temperature crosslinked ethylene-vinyl acetate copolymer resin. Furthermore, the ethylene-vinyl acetate copolymer resin may also be a modified ethylene-vinyl acetate resin such as a saponified ethylene-vinyl acetate copolymer or a hydrolyzed ethylene-vinyl acetate.

[0048] The ethylene-vinyl acetate copolymer resin preferably has a vinyl acetate content of 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less, as measured in accordance with JIS K6730 "Testing Methods for Ethylene-Vinyl Acetate Resins" or JIS K6924-2:1997. By adjusting the vinyl acetate content to be equal to or greater than these lower limits, the adhesion of the laminate to the adherend is enhanced. Furthermore, by adjusting the vinyl acetate content to be equal to or less than these upper limits, the breaking strength of the adhesive film is enhanced.

[0049] (Plasticizer) The thermoplastic resin composition preferably contains a plasticizer in addition to the thermoplastic resin. By containing a plasticizer in the thermoplastic resin composition, the adhesive film becomes more flexible and the impact absorption can be further improved.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 (PPG) is preferred.

[0056] 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. Among these, polyoxypropylene diglyceryl ether (DGP) is preferred. 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 the alcohol plasticizer include various polyhydric alcohols such as butanediol, hexanediol, trimethylolpropane, and pentaerythritol. Among these, trimethylolpropane is preferred.

[0057] 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.

[0058] The content of the plasticizer in the thermoplastic resin composition is not particularly limited, but is preferably 20 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the thermoplastic resin. When the content of the plasticizer is 20 parts by mass or more, the adhesive film becomes moderately flexible, and the adhesiveness of the adhesive film improves. Furthermore, the thickness change amount also tends to be large. On the other hand, when the content of the plasticizer is 70 parts by mass or less, separation of the plasticizer from the adhesive film is prevented. Furthermore, a decrease in the storage modulus can also be prevented. The content of the plasticizer is more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and more preferably 65 parts by mass or less, even more preferably 60 parts by mass or less, even more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less.

[0059] The thermoplastic resin composition may contain, in addition to the plasticizer, known additives that are used in combination with thermoplastic resins. That is, the thermoplastic resin composition may be composed of a thermoplastic resin such as a polyvinyl acetal resin, or a thermoplastic resin and a plasticizer, but may also contain additives other than the plasticizer that are blended as needed. Specific examples of additives other than the plasticizer include ultraviolet absorbers, infrared absorbers, antioxidants, light stabilizers, adhesion modifiers, colorants (pigments or dyes), fluorescent brighteners, and crystal nucleating agents.

[0060] (Storage modulus at 25°C) The storage modulus of the adhesive film at 25°C is preferably 3 MPa or more and 11.3 MPa or less. When the storage modulus of the adhesive film is 3 MPa or more, the mechanical strength of the adhesive film can be further increased. When the storage modulus of the adhesive film is 11.3 MPa or less, the flexibility of the adhesive film can be further increased. From this viewpoint, the storage modulus of the adhesive film at 25°C is more preferably 5 MPa or more and 10.0 MPa or less, and even more preferably 6.6 MPa or more and 7.3 MPa or less. The storage modulus of the adhesive film at 25°C can be measured by the method described in the Examples below. The storage modulus of the adhesive film at 25°C can be adjusted by the type of resin constituting the adhesive film, the content of plasticizer, etc.

[0061] (Root-mean-square slope Sdq) The root-mean-square slope Sdq of the release surface of the adhesive film after peeling off the first release substrate is preferably 3 or more and 20 or less. Increasing the Sdr of the first release substrate and increasing the Sdq of the adhesive film surface makes it easier for unevenness to remain during lamination, thereby increasing the peel strength between the first release substrate and the adhesive film and making it easier to achieve the peel strength ratio (A / B) of 4 or more. If the root-mean-square slope Sdq of the release surface of the adhesive film after peeling off the first release substrate is 20 or less, the pressure and temperature of the pre-press when bonding a glass plate to the release surface of the adhesive film can be reduced. From this perspective, the root-mean-square slope Sdq of the release surface of the adhesive film after peeling off the first release substrate is more preferably 5.5 or more and 20 or less, and even more preferably 6 or more and 13 or less. The root mean square slope Sdq of the release surface of the adhesive film after the first release substrate has been peeled off can be measured by the method described in the Examples below. The root mean square slope Sdq of the release surface of the adhesive film after the first release substrate has been peeled off can be adjusted by the uneven shape formed on the surface of the first release substrate.

[0062] (Surface roughness Rzjis) The surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate is preferably 3 μm or more and 10 μm or less. If the surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate is 3 μm or more, the peel strength between the first release substrate and the adhesive film can be increased, and the peel strength ratio (A / B) can be easily set to 4 or more. If the surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate is 10 μm or less, the pressure and temperature of the pre-press when bonding a glass plate to the release surface of the adhesive film can be reduced. From this viewpoint, the surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate is more preferably 3 μm or more and 9 μm or less, and even more preferably 3 μm or more and 8 μm or less. The surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate can be measured by the method described in the Examples below. Furthermore, the surface roughness Rzjis of the release surface of the adhesive film after peeling off the first release substrate can be adjusted by the uneven shape formed on the surface of the first release substrate. When a first release substrate is provided, it is advisable to peel off the first release substrate and measure the exposed surface of the adhesive film.

[0063] The surface roughness Rzjis of the surface of the adhesive film opposite to the surface that contacts the first release substrate is preferably 3 μm or more and 10 μm or less. If the surface roughness Rzjis of the surface of the adhesive film opposite to the surface that contacts the first release substrate is 3 μm or more, the tackiness is reduced, making it easier to readjust the bonding position after placement on the adherend. If the surface roughness Rzjis of the surface of the adhesive film opposite to the surface that contacts the first release substrate is 10 μm or less, the pressure and temperature of the pre-press when bonding the laminate can be reduced. From this perspective, the surface roughness Rzjis of the surface of the adhesive film opposite to the surface that contacts the first release substrate is more preferably 3.5 μm or more and 9.5 μm or less, and even more preferably 3.5 μm or more and 9.5 μm or less. The surface roughness Rzjis of the surface of the adhesive film opposite to the surface that contacts the first release substrate can be measured by the method described in the Examples below. The surface roughness Rzjis of the opposite surface may be measured directly on the exposed surface of the adhesive film when the second releasable substrate described below is not provided. Alternatively, when the second releasable substrate is provided, the second releasable substrate may be peeled off and the surface of the exposed adhesive film may be measured. Furthermore, the surface roughness Rzjis of the surface of the adhesive film opposite the surface that contacts the first releasable substrate may be adjusted by forming an uneven shape on the surface of the adhesive film by a method such as embossing.

[0064] The adhesive film preferably has an uneven shape on the surface that contacts the first release substrate. It is also preferable that the adhesive film has an uneven shape on the surface opposite to the surface that contacts the first release substrate. The shape of the surface of the adhesive film is not particularly limited, but it is preferably a shape in which random convexities are formed. When the surface of the adhesive film that contacts the first release substrate has an uneven shape, the contact area between the first release substrate and the adhesive film increases, making it easier to increase the peel strength A between the first release substrate and the adhesive film. On the other hand, when the surface opposite to the surface that contacts the first release substrate has an uneven shape, the tackiness of the surface of the adhesive film is reduced, making it easier to readjust the bonding position after placement on the adherend.

[0065] The uneven shape of the surface of the adhesive film on the first releasable substrate side may be formed by transferring the uneven shape of the surface of the first releasable substrate. Similarly, the uneven shape of the surface of the adhesive film opposite the first releasable substrate may be formed by transferring the uneven shape of the surface of the second releasable substrate described below. In addition, the uneven shape of the surface of the adhesive film (particularly the surface opposite the first releasable substrate) may be formed by embossing the adhesive film with an embossing roll.

[0066] (Visible light transmittance) The visible light transmittance of the adhesive film after all the releasable substrates are peeled from the laminate is preferably less than 90%.If the release surface of the adhesive film after peeling off the first releasable substrate has an uneven shape, light is scattered on the release surface of the adhesive film, and the visible light transmittance of the adhesive film after all the releasable substrates are peeled off from the laminate is reduced.Therefore, if an uneven shape is formed on the release surface of the adhesive film after peeling off the first releasable substrate, the visible light transmittance of the adhesive film after all the releasable substrates are peeled off from the laminate is reduced.Therefore, if the visible light transmittance of the adhesive film after peeling off all the releasable substrates from the laminate is less than 90%, the peel strength between the first releasable substrate and the adhesive film can be increased, and it is easier to make the peel strength ratio (A / B) 4 or more.In addition, if the visible light transmittance of the adhesive film after peeling off all the releasable substrates from the laminate is less than 90%, an uneven shape is formed on the adhesive film, making it easier to peel off the cut sheet temporarily adhered to the adherend from the adherend. From this viewpoint, the visible light transmittance of the adhesive film after all the releasable substrates have been peeled from the laminate is more preferably 88% or less, and even more preferably 87% or less. The lower limit of the range of the visible light transmittance of the adhesive film after all the releasable substrates have been peeled from the laminate is not particularly limited, but is usually 80%. The visible light transmittance of the adhesive film after all the releasable substrates have been peeled from the laminate can be measured by the method described in the Examples below. In addition, the visible light transmittance of the adhesive film after all the releasable substrates have been peeled from the laminate can be adjusted by the uneven shape of the surface of the adhesive film after all the releasable substrates have been peeled from the laminate. In addition, the uneven shape of the surface of the adhesive film after the release substrates have been peeled can be adjusted by adjusting the uneven shape of the surface of the release substrate that contacts the adhesive film, or by the manufacturing method described below.

[0067] (Thickness) The thickness of the adhesive film is not particularly limited, but is preferably 10 μm or more and 3 mm or less, more preferably 30 μm or more and 2 mm or less, and even more preferably 100 μm or more and 1 mm or less. When the thickness of the adhesive film is equal to or more than the above-mentioned lower limit, the impact resistance can be improved and adhesion to laminated glass members and the like can be easily ensured. On the other hand, when the thickness is equal to or less than the above-mentioned upper limit, the thickness of the laminated glass can be prevented from becoming thicker than necessary.

[0068] (Structure) The adhesive film may be a single-layer film having a single-layer structure. When the adhesive film is composed of a single layer, the adhesive film of the single-layer structure may have the composition as described above for the thermoplastic resin composition. That is, the layer constituting the single-layer adhesive film contains the above-mentioned thermoplastic resin, and may contain a plasticizer as needed, and may also contain additives other than the plasticizer as appropriate.

[0069] The adhesive film may be a multilayer film having two or more layers. Each resin layer of the multilayer film may have the composition as described above for the thermoplastic resin composition. That is, each resin layer contains a thermoplastic resin as described above for the thermoplastic resin composition, and may contain a plasticizer as needed, and additives other than the plasticizer may be appropriately blended. Preferably, each resin layer contains the polyvinyl acetal resin described above as the thermoplastic resin. Details of the thermoplastic resin, plasticizer, and additives in each resin layer of the multilayer film, and details of the content of each component, are as described above for the thermoplastic resin composition. However, the thermoplastic resin used as the basis for the content is the thermoplastic resin contained in each layer. In the multilayer film, each resin layer may have the same composition or different compositions.

[0070] The method for producing the adhesive film is not particularly limited, and it may be produced by a conventionally known method, such as extrusion molding or press molding, but it is preferable to produce it by extrusion molding, as described in detail below.

[0071] [Second Releasable Substrate] The laminate of the present invention may have no releasable substrate on the other side of the adhesive film, leaving the surface of the adhesive film exposed, or may further have a second releasable substrate on the other side of the adhesive film in addition to the first releasable substrate on one side of the adhesive film. This makes it possible to prevent the surface of the adhesive film from being scratched or foreign matter from adhering to the surface of the adhesive film before the laminate is temporarily bonded to the adherend.

[0072] (Peel strength) When the peel strength between the second releasable substrate and the adhesive film is C (N / 25 mm), the peel strength C is preferably smaller than the peel strength A. This makes it possible to prevent the adhesive film from peeling from the first releasable substrate when peeling the second releasable substrate from the laminate. From this perspective, the value obtained by subtracting the peel strength C from the peel strength A is preferably 0.1 N / 25 mm or more, more preferably 0.15 N / 25 mm or more. The upper limit of the range of the value obtained by subtracting the peel strength C from the peel strength A is not particularly limited, but is usually less than 6 N / 25 mm, for example, 5 N / 25 mm or less, 4 N / 25 mm or less, 3 N / 25 mm or less, 2 N / 25 mm or less, or 1 N / 25 mm or less.

[0073] The peel strength C is preferably within the range obtained by subtracting the peel strength C from the peel strength A. The value is not particularly limited, but is, for example, 0.5 N / 25 mm or more and 10 N / 25 mm or less, preferably 1.5 N / 25 mm or more and 5.5 N / 25 mm or less. The peel strength C when peeling the second releasable substrate from the adhesive film can be measured by the method described in the Examples below. The peel strength C when peeling the second releasable substrate from the adhesive film can be adjusted by the uneven shape of the surface of the second releasable substrate, the type of resin of the second releasable substrate, etc. When the second releasable substrate has the above-mentioned adhesive strength adjustment layer, the peel strength C can be adjusted by the type of resin constituting the adhesive strength adjustment layer. It can also be adjusted by adjusting the temperature of the releasable substrate in the lamination mechanism 15 described below. For example, in the embodiment shown in FIG. 2 described below, the peel strength C can be lower than the peel strength A by lowering the temperature of the second roll 36 below the temperature of the first roll 35.

[0074] The second release substrate is not particularly limited as long as it can be peeled from the adhesive film.Similar to the first release substrate, the second release substrate can be, for example, a release film, a release paper, a mesh material, a metal, a prepreg, etc.These release substrates can be used alone or in combination of two or more.In addition, the release film, the release paper, the mesh material, the metal, and the prepreg can be the same as those that can be used for the first release substrate, so the description of the release film, the release paper, the mesh material, the metal, and the prepreg will be omitted.

[0075] As with the first release substrate, an uneven shape may also be formed on the surface of the second release substrate. If the peel strength C is smaller than the peel strength A, the surface shape of the second release substrate is not particularly limited, and may be a configuration in which protrusions or grooves are formed, and the protrusions and grooves are regularly arranged, or a shape in which a large number of random recesses are formed. Among these, it is preferable that the surface shape of the second release substrate is a shape in which a large number of random recesses are formed. The uneven shape on the surface of the second release substrate is also transferred to the adhesive film, thereby reducing the tackiness of the release surface of the adhesive film after peeling the second release substrate, making it easier to readjust the bonding position after placing it on the adherend. If the peel strength C is smaller than the peel strength A, the uneven shape on the surface of the second release substrate is not particularly limited. Methods for forming a large number of recesses and a large number of protrusions on the surface of the second release substrate include, for example, an embossing roll method, a calender roll method, a profile extrusion method, and a melt fracture method. Among these, embossing by an embossing roll method is preferred. In the embossing roll method, the surface of a roll used for embossing is given random irregularities using a blasting agent, and then the iron roll is vertically ground to prepare an embossing roll for forming random depressions on the surface of the release film, and this embossing roll may be used.

[0076] In plan view, the outer periphery of the second release substrate may coincide with the outer periphery of the adhesive film, or at least a portion of the outer periphery of the second release substrate may extend outward relative to the outer periphery of the adhesive film. Since the portion of the second release substrate extending outward relative to the outer periphery of the adhesive film can be gripped to easily peel the second release substrate from the laminate, it is preferable that at least a portion of the outer periphery of the second release substrate extends outward relative to the outer periphery of the adhesive film. From the viewpoint of ease of gripping the extending portion of the second release substrate, the length in the extending direction of the extending portion of the second release substrate is preferably 5 mm or more and 100 mm or less, more preferably 10 mm or more and 50 mm or less, and even more preferably 15 mm or more and 40 mm or less. Note that at least the length in the longitudinal direction of the second release substrate may be longer than the length in the longitudinal direction of the adhesive film, and the portion extending from the adhesive film may be provided on the first release substrate.

[0077] <Method for producing laminate> Hereinafter, one embodiment of the method for producing a laminate of the present invention will be described. In one embodiment of the method for producing a laminate described below, a laminate is obtained by laminating a first release substrate and a second release substrate on a resin layer (adhesive film) obtained by extruding a molten thermoplastic resin composition. However, in this embodiment, the second release substrate laminated on the laminate may be appropriately peeled and removed, or a laminate may be produced in which a substrate is laminated on only one side of the resin layer (adhesive film).

[0078] The manufacturing method according to this embodiment is carried out using a manufacturing apparatus shown in Fig. 1. The manufacturing apparatus 10 in this embodiment includes an extruder 11, a mold 12, a feeding mechanism 13, a substrate heating mechanism 14, a laminating mechanism 15, an annealing section 16, a cooling mechanism 17, and a winding mechanism 18. In the manufacturing apparatus 10 in this embodiment, a laminate 25 obtained by laminating first and second release substrates 21, 22 and a resin layer 20 fed from the feeding mechanism 13 is wound into a roll by the winding mechanism 18 to obtain a roll-shaped laminate.

[0079] In the manufacturing method according to this embodiment, the processes from unwinding the first and second releasable substrates 21, 22 to winding them up by the winding mechanism 18 are carried out between rolls, so-called roll-to-roll. When the substrate, laminate, etc. are transported by roll-to-roll, the substrate and laminate may be transported by, but not particularly limited to, a pinch roll 41 or the like and guided by guide rolls 42, 43, etc. However, the pinch roll 41 and guide rolls 42, 43 shown in FIG. 1 are merely examples and are not particularly limited.

[0080] The extruder 11 is not particularly limited as long as it can melt and knead the thermoplastic resin composition, and may be a single-screw extruder with one screw inside the cylinder, or a twin-screw extruder with two screws in parallel. The thermoplastic resin composition is introduced into the extruder 11 through a raw material supply port on the upstream side of the cylinder, and is melt-kneaded by the screws inside the cylinder while being sent downstream. The melt-kneaded thermoplastic resin composition is supplied to a mold 12 connected to the extruder 11. In the mold 12, the thermoplastic resin composition is extruded from a die provided in the mold 12 into a sheet-like resin layer 20, which is then supplied to a lamination mechanism 15. The temperature at which the thermoplastic resin composition is extruded from the mold 12 (the temperature at the mold outlet) is preferably higher than the softening temperature T1 (°C) described below and at a temperature at which the tan δ of the thermoplastic resin composition is 1 or greater, more preferably at a temperature at which the tan δ is 1.5 or greater. From the viewpoint of suppressing thermal degradation of the thermoplastic resin composition, the temperature is preferably such that tan δ is 2.2 or less, and more preferably such that tan δ is 2.0 or less. When the thermoplastic resin composition is mainly composed of polyvinyl butyral, the temperature during extrusion can be, for example, about 180 to 220°C. The tan δ of the thermoplastic resin composition can be measured, for example, by viscoelasticity measurement using a dynamic viscoelasticity measuring device ("DVA-200" manufactured by IT Measurement & Control Co., Ltd.). The tan δ of the thermoplastic resin composition can be measured, for example, in shear mode under conditions of a frequency of 10 Hz and a strain of 0.02%.

[0081] In the extruder 11, the moisture content of the thermoplastic resin composition may be appropriately adjusted to appropriately adjust the moisture content of the adhesive film to be obtained. The moisture content may be adjusted, for example, by feeding a thermoplastic resin composition whose moisture content has been adjusted in advance into the extruder, or by reducing the moisture content of the thermoplastic resin composition by vacuum suction or the like from a vent of the extruder. Alternatively, the moisture content of the thermoplastic resin composition may be increased by supplying water from the raw material supply port or a moisture supply port provided separately from the raw material supply port.

[0082] In the above description, it is assumed that the thermoplastic resin composition extruded from the mold 12 is a single resin layer, but a co-extrusion method may be employed to extrude multiple resin layers. When multiple resin layers are extruded, multiple extruders may be provided and connected to the mold 12, and the thermoplastic resin composition may be extruded from the mold 12 to form multiple resin layers. In this case, the thermoplastic resin compositions constituting each resin layer may be the same or different.

[0083] The unwinding mechanism 13 includes first and second unwinding mechanisms 31 and 32. A wound body on which the first releasable substrate 21 and the second releasable substrate 22 are wound in a roll shape is attached to each of the first and second unwinding mechanisms 31 and 32. The first unwinding mechanism 31 unwinds the first releasable substrate 21 from the wound body and supplies the first releasable substrate 21 to the laminating mechanism 15. The second unwinding mechanism 32 unwinds the second releasable substrate 22 from the wound body and supplies the second releasable substrate 22 to the laminating mechanism 15. Typically, the first and second releasable substrates 21 and 22 are preferably supplied from the unwinding mechanism 13 to the laminating mechanism 15 while being guided by one or more guide rolls (not shown).

[0084] The first releasable substrate 21 and the second releasable substrate 22 may be embossed by embossing rolls 51 and 52, respectively, before being laminated on the resin layer 20. The embossing rolls 51 and 52 apply an embossed pattern to the first releasable substrate 21 and the second releasable substrate 22, respectively, between an engraved metal roll and a rubber roll. This makes it possible to impart the above-described uneven shape to the surface of the first releasable substrate and the surface of the second releasable substrate, respectively. The embossing is not particularly limited, and may be performed, for example, after being unwound from the unwinding mechanism 13 and before the resin layer 20 is laminated thereon. However, it is preferable to perform the embossing after being unwound from the unwinding mechanism 13 and before being heated by the substrate heating mechanism 14. However, it is also possible to use embossed substrates for the first releasable substrate 21 and the second releasable substrate 22, and not provide the embossing rolls 51 and 52.

[0085] Furthermore, the first releasable substrate 21 may be subjected to a surface modification treatment, such as a plasma modification treatment or a corona treatment, before being laminated on the resin layer 20. Similarly, the second releasable substrate 22 may be subjected to a surface modification treatment, such as a plasma modification treatment or a corona treatment, before being laminated on the resin layer 20.

[0086] The plasma modification treatment may be performed on the surfaces of the first and second releasable substrates 21 and 22 that are to be laminated on the resin layer 20. When the plasma modification treatment is performed on the first releasable substrate 21, the second releasable substrate 22, or both, the surfaces are modified to facilitate adhesion to the resin layer 20. For example, oxygen plasma may be used for the plasma treatment.

[0087] The surface modification treatment is not particularly limited, and may be performed, for example, after being fed from the feeding mechanism 13 and before the resin layer 20 is laminated, but is preferably performed after being fed from the feeding mechanism 13 and before being heated by the substrate heating mechanism 14. The surface modification treatment may be performed while being transported roll-to-roll as described above, and for example, the plasma treatment may be performed using a known plasma treatment device.

[0088] In this embodiment, the first and second releasable substrates 21, 22 fed from the first and second feed mechanisms 31, 32, respectively, are preferably heated by the substrate heating mechanism 14 and then supplied to the laminating mechanism 15. Specifically, the first releasable substrate 21 is preferably heated by the substrate heating mechanism 14 (i.e., before laminating the first releasable substrate 21 on the resin layer 20) to a temperature equal to or higher than the softening temperature T1 (°C) of the resin layer 20, which will be described later. By preheating the first releasable substrate 21 to a temperature equal to or higher than the softening temperature T1, the first releasable substrate 21 undergoes thermal shrinkage before being laminated on the resin layer 20. Therefore, when the first releasable substrate 21 is laminated on the extruded resin layer 20, shrinkage of the first releasable substrate 21 due to the heat of the resin layer 20, which would cause wrinkles, can be prevented. Furthermore, by the substrate heating mechanism 14, the first releasable substrate 21 is preferably heated to approximately ±20°C, and even more preferably to approximately ±15°C, relative to the temperature R1 of the resin layer 20 when the first releasable substrate 21 is laminated, as described below. The heating time for the first releasable substrate 21 in the substrate heating mechanism 14 is not particularly limited, but is, for example, 0.1 to 30 seconds, preferably 0.1 to 15 seconds. After heating in the substrate heating mechanism 14, the temperature of the first releasable substrate 21 is preferably maintained at or above the softening temperature T1 (°C) before being laminated on the resin layer 20 in the laminating mechanism 15. By laminating in this manner, the first releasable substrate 21 is prevented from shrinking due to heating by the resin layer 20 during lamination, and the occurrence of wrinkles or the like in the first releasable substrate 21 can be further prevented.

[0089] Similarly, the second releasable substrate 22 is preferably heated by the substrate heating mechanism 14 (i.e., before laminating the second releasable substrate 22 on the resin layer 20) to a temperature equal to or higher than the softening temperature T1 (°C) of the resin layer 20, which will be described later. By preheating the second releasable substrate 22 to a temperature equal to or higher than the softening temperature T1, the second releasable substrate 22 will thermally shrink before being laminated on the resin layer 20. This prevents the second releasable substrate 22 from shrinking due to the heat of the resin layer 20 and causing wrinkles when the second releasable substrate 22 is laminated on the extruded resin layer 20. The substrate heating mechanism 14 more preferably heats the second releasable substrate 22 to a temperature that is approximately ±20°C, and even more preferably ±15°C, of ​​the temperature R2 of the resin layer 20 when the second releasable substrate 22 is laminated, which will be described later. The heating time for the second releasable substrate 22 in the substrate heating mechanism 14 is not particularly limited, but is, for example, 0.1 to 30 seconds, preferably 0.1 to 15 seconds. After heating in the substrate heating mechanism 14, the second releasable substrate 22 is more preferably laminated onto the resin layer 20 while the temperature of the second releasable substrate 22 remains at or above the softening temperature T1 (°C). By laminating in this manner, the second releasable substrate 22 is prevented from shrinking due to heating by the resin layer 20 during lamination, and the occurrence of wrinkles and the like in the second releasable substrate 22 can be further prevented.

[0090] It is particularly preferable that the first and second releasable substrates 21, 22 are both heated to a temperature within the above range before being laminated on the resin layer 20, from the viewpoint of suppressing thermal shrinkage of both the first and second releasable substrates 21, 22 and preventing warping and the like. The first and second releasable substrates 21, 22 may be heated to the same temperature or to different temperatures by the substrate heating mechanism 14. By heating to different temperatures, the adhesive film made of a thermoplastic resin composition and the first releasable substrate 21 and the second releasable substrate 22 can be laminated at different temperatures. As a result, the adhesive strength between the first releasable substrate 21, the second releasable substrate 22 and the adhesive film made of a thermoplastic resin composition can be adjusted.

[0091] The substrate heating mechanism 14 is not particularly limited, and examples thereof include a heating roll and a heating space. The substrate heating mechanism 14 may heat the first and second releasable substrates 21, 22 along any of the paths along which the substrates are supplied from the unwinding mechanism 13 to the laminating mechanism 15. When a heating roll is used, the first releasable substrate 21 may be advanced along the heating roll along any of the paths. The heating space is a space heated in a high-temperature environment, and may be composed of, for example, a thermostatic bath, a heating chamber, a heating furnace, or the like. When a heating space is used, the first releasable substrate 21 may be passed through a heating space adjusted to a high-temperature environment. The second releasable substrate 22 may also be heated in the same manner as the first releasable substrate 21 by a heating space, a heating roll, or the like. The temperature inside the heating space constituting the substrate heating mechanism 14 and the temperature of the surface of the heating roll in contact with the substrate may be set appropriately so that the first and second releasable substrates 21, 22 are within the above-mentioned temperature range, specifically, the temperature may be set to be equal to or higher than the softening temperature T1 (°C) of the resin layer 20. For convenience, FIG. 1 shows a configuration in which both the first and second releasable substrates 21, 22 are heated by one substrate heating mechanism 14, but two or more substrate heating mechanisms 14 may be provided to independently heat the first and second releasable substrates 21, 22.

[0092] The laminating mechanism 15 laminates the first and second releasable substrates 21, 22 supplied from the delivery mechanism 13 onto the thermoplastic resin composition (resin layer 20) extruded from the mold 12. The laminating mechanism 15 includes, for example, first and second rolls 35, 36, as shown in FIG. 2 . The first roll 35 is a cast roll, and the first and second releasable substrates 21, 22 are laminated onto the resin layer 20 on the first roll 35. The second roll 36 is a nip roll, and is arranged at a fixed interval from the first roll 35. The first releasable substrate 21, the resin layer 20, and the second releasable substrate 22 supplied between the first roll 35 and the second roll 36 can be pressed together by applying pressure. It is preferable that the pressure applied to the second roll 36 can be controlled. By being able to control the pressure applied, it is possible to appropriately control the pressure depending on the types of the first and second releasable substrates 21, 22, the thickness of the resin layer 20, etc. The pressure of the second roll 36 can be adjusted by adjusting the distance from the first roll 35, for example.

[0093] The first and second rolls 35, 36 may both be metal rolls or rubber rolls with rubber wound around the outer periphery of a metal core, but it is preferable to use one as a metal roll and the other as a rubber roll. Using one as a metal roll and the other as a rubber roll eliminates press unevenness and enables the substrates 21, 22 to be stably laminated to the resin layer 20. Furthermore, the first and second rolls 35, 36 may each have a temperature control mechanism by flowing a fluid such as steam, oil, or water therein, or by introducing a heater or electromagnetic induction. The first and second releasable substrates 21, 22 and the resin layer 20 may be heated by a temperature control mechanism. The temperature control mechanism makes it easier to adjust the temperature during lamination of the first and second releasable substrates 21, 22 and the resin layer 20 within the desired range.

[0094] In this embodiment, the first releasable substrate 21 supplied from the unwinding mechanism 13 is supplied to the first roll 35, as shown in Fig. 2, and is transported on and along the first roll 35, and is supplied between the first and second rolls 35, 36. The second releasable substrate 22 supplied from the unwinding mechanism 13 is supplied to the second roll 36, and is transported on and along the second roll 36, and is supplied between the first and second rolls 35, 36. It is preferable that the first and second rolls 35, 36 rotate in opposite directions while the first and second releasable substrates 21, 22 are being supplied.

[0095] On the other hand, the thermoplastic resin composition (resin layer 20) extruded and melted from the mold 12 is supplied between the first and second rolls 35, 36. Then, between the first and second rolls 35, 36, a first releasable substrate 21 and a second releasable substrate 22 are laminated on both sides of the supplied resin layer 20, respectively, to obtain a laminate 25. At this time, the first releasable substrate 21 and the second releasable substrate 22 are simultaneously laminated on the resin layer 20. In this embodiment, by laminating the first and second releasable substrates 21, 22 on both sides of the resin layer 20, respectively, between the first and second rolls 35, 36, the thermal history of the laminate 25 is likely to be the same on the front and back, making it less likely to warp and further improving dimensional stability.

[0096] In this embodiment, the temperature R1 of the resin layer 20 when the first releasable substrate 21 is laminated on the resin layer 20 is preferably equal to or higher than the softening temperature T1 (°C) of the resin layer 20. The softening temperature T1 of the resin layer 20 is a temperature that satisfies the following formulas (1) and (2): T1>Tg (1) tan δ(T1+n)-tan δ(T1+n-1)>0 (n=1 to 5) (2) Note that Tg in formula (1) is the temperature at the highest maximum value on a tan δ-temperature curve that is obtained by measuring the tan δ of the resin layer 20, for example, at 0 to 240°C, and plotting the tan δ on the vertical axis and the temperature on the horizontal axis. Tg is also the glass transition temperature of the resin layer 20. T1 is an integer value and the minimum value that satisfies formulas (1) and (2). Tan δ (T1+n) is the value of tan δ at T1+n (°C). n is an integer of 1 or more and 5 or less, and formula (2) is satisfied when n is any of 1 to 5. Note that tan δ may be measured under the conditions described in the examples below.

[0097] In this embodiment, the first and second releasable substrates 21, 22 are simultaneously laminated onto the resin layer 20. Therefore, the temperature R1 of the resin layer 20 when the first releasable substrate 21 is laminated onto the resin layer 20 is the same as the temperature R2 of the resin layer 20 when the second releasable substrate 22 is laminated onto the resin layer 20.

[0098] An example of a tan δ-temperature curve is shown in FIG. 3. In the tan δ-temperature curve of the resin layer 20, as shown in FIG. 3, if the temperature is further increased from the temperature (Tg) at which the tan δ-temperature curve reaches its maximum value, tan δ decreases and then increases. The temperature at which the decrease turns to an increase is the softening temperature T1 that satisfies the above formulas (1) and (2). The softening temperature T1 of the resin layer 20 is the temperature at which the resin layer 20 begins to soften. Therefore, if the temperature of the resin layer R1 when the first releasable substrate 21 is laminated is equal to or higher than the softening temperature T1, it becomes possible to laminate the first releasable substrate 21 to the resin layer 20 with an appropriate adhesive strength. Therefore, it is possible to prevent the first releasable substrate 21 from unintentionally peeling from the resin layer 20 in subsequent processes.

[0099] Furthermore, it is more preferable that the temperature R1 of the resin layer 20 when the first releasable substrate 21 is laminated on the resin layer 20 is equal to or higher than the softening temperature T1 (°C) and a temperature at which tan δ is 0.15 or higher. At a temperature equal to or higher than T1 (°C) and at which tan δ is 0.15 or higher, the resin layer 20 starts to soften and viscosity becomes more dominant in the resin layer 20. Therefore, by making the temperature R1 higher than this temperature, the first releasable substrate 21 can be more appropriately bonded to the resin layer 20. From the above viewpoints, it is more preferable that the temperature R1 is a temperature that is equal to or higher than the softening temperature T1 of the resin layer 20 and at which tan δ is 0.19 or higher, even more preferable that it is a temperature that is equal to or higher than the softening temperature T1 and at which tan δ is 0.3 or higher, particularly preferable that it is a temperature that is equal to or higher than the softening temperature T1 and at which tan δ is 0.5 or higher, even more preferable that it is a temperature that is equal to or higher than the softening temperature T1 and at which tan δ is 0.75 or higher, and particularly preferable that it is a temperature that is equal to or higher than the softening temperature T1 and at which tan δ is 1 or higher.

[0100] Furthermore, it is more preferable that the temperature R1 of the resin layer 20 when the first releasable substrate 21 is laminated on the resin layer 20 is equal to or higher than the softening temperature T1 (°C) and is at least 50°C higher than the glass transition temperature of the resin layer 20. Even at such a temperature, the resin layer 20 begins to soften and viscosity becomes more dominant in the resin layer 20, so that by having the temperature R1 higher than this temperature, the first releasable substrate 21 can be more appropriately bonded to the resin layer 20. From the same viewpoint, it is even more preferable that the temperature is equal to or higher than the softening temperature T1 (°C), is at least 50°C higher than the glass transition temperature of the resin layer 20, and is at least a temperature that satisfies the above-mentioned value of tan δ.

[0101] Furthermore, the temperature R1 is not particularly limited, but from the viewpoint of preventing the resin layer 20 from softening or melting more than necessary when the resin layer 20 is laminated to the first releasable substrate 21 and the second releasable substrate 22, it is preferable that the temperature R1 be below a certain level. For example, a temperature that is equal to or higher than the softening temperature T1 and has a tan δ of 2 or less is preferred, and a temperature that is equal to or higher than the softening temperature T1 and has a tan δ of 1.5 or less is more preferred.

[0102] Furthermore, the thermoplastic resin composition extruded from the mold 12 is extruded at a temperature equal to or higher than the softening temperature T1, and the temperature drops after extrusion, but in this embodiment, after the extrusion of the thermoplastic resin composition, before the temperature of the thermoplastic resin composition drops below the softening temperature T1 (°C), it is preferable to laminate the first releasable substrate 21 onto the thermoplastic resin composition (resin layer 20) in the laminating mechanism 15. This allows the thermoplastic resin composition (resin layer 20) to be maintained in a softened state by the residual heat from extrusion while being transferred from the mold 12 to the laminating mechanism 15, without being heated by a separately provided heating means, and to be laminated onto the first releasable substrate 21.

[0103] In the laminating mechanism 15, the laminate 25 obtained by laminating the first and second releasable substrates 21, 22 is sent to the annealing section 16. In the annealing section 16, the laminate 25 is maintained at or above the softening temperature T1 of the thermoplastic resin composition (resin layer 20). By maintaining the laminate 25 at or above the softening temperature T1 in the annealing section 16, stress relaxation is promoted, distortion generated in the resin layer 20 during extrusion is eliminated, and shrinkage of the resin layer 20 due to subsequent cooling or the like can be prevented. The annealing section may be maintained or heated by a heating mechanism, or may be slowly cooled in a room temperature environment, etc. During slow cooling, the laminate 25 may be appropriately transported using guide rolls at room temperature, etc. However, when slowly cooled in the annealing section 16, it is preferable that the laminate 25 be slowly cooled in an environment with a temperature higher than the cooling temperature in the cooling mechanism described below. The laminate 25 is obtained by laminating at least the resin layer 20 to the first and second releasable substrates 21, 22 at or above the softening temperature T1 as described above. Therefore, the laminate 25 (particularly the resin layer 20) may be maintained at or above the softening temperature T1 from the time it is formed in the laminating mechanism 15 until it is supplied to the annealing section 16. According to this embodiment, the resin layer 20 is maintained at a temperature equal to or higher than the softening temperature T1 for a long period of time after the first and second releasable substrates 21, 22 are laminated, which further promotes stress relaxation and further prevents the resin layer 20 from shrinking due to subsequent cooling, etc. However, the temperature of the laminate 25 (particularly the resin layer 20) may be lowered to a temperature below the softening temperature T1 from the time it is formed in the laminating mechanism 15 until it is supplied to the annealing section 16.

[0104] When the annealing section 16 has a heating mechanism, the heating mechanism may be, but is not limited to, a heating roll, a heating space, or the like. When a heating roll is used, the laminate 25 formed in the laminating mechanism 15 may be supplied to the heating roll and advanced along the heating roll. The heating space is a space heated in a high-temperature environment, and may be, for example, a thermostatic bath, a heating chamber, a heating furnace, or the like. When a heating space is used, the laminate 25 may be passed through a heating space adjusted to a high-temperature environment. The temperature inside the space constituting the annealing section 16 and the temperature of the surface of the heating roll in contact with the substrate may be appropriately set so that the laminate is within the above-mentioned temperature range; specifically, the temperature may be set to be equal to or higher than the softening temperature T1 (°C) of the resin layer 20.

[0105] In the annealing section 16, from the viewpoint of appropriately relaxing stress and suppressing shrinkage during cooling by the cooling mechanism 17 described below, the laminate 25 is preferably maintained at or elevated in temperature to a temperature range equal to or higher than the softening temperature T1 of the resin layer 20 and having a tan δ of 1 or less, and even more preferably maintained at or elevated in temperature to a temperature range equal to or higher than the softening temperature T1 and having a tan δ of 0.75 or less. Specifically, for example, when the resin layer 20 is primarily composed of polyvinyl butyral, the temperature can be approximately 60 to 160°C. The time during which the laminate 25 is maintained at or above the softening temperature T1 (°C) in the annealing section 16 is not particularly limited, but is, for example, 0.1 to 360 seconds, preferably 3 to 120 seconds.

[0106] The laminate 25, which has been maintained or heated to or above the melting temperature T1 in the annealing section 16, is then sent to the cooling mechanism 17, where the laminate 25 is cooled. By cooling the laminate 25 in the cooling mechanism 17, distortion is less likely to occur during subsequent winding, and the dimensional stability of the resin layer 20 and the laminate 25 can be further improved. Note that, because the resin layer 20 is supported by the substrate during cooling in the cooling mechanism 17, shrinkage during cooling is appropriately suppressed. In particular, in this embodiment, because the substrates 21 and 22 are laminated on both sides of the resin layer 20, shrinkage can be further appropriately suppressed, and dimensional stability can be improved.

[0107] Here, from the viewpoint of making the laminate 25 less likely to be distorted in the subsequent steps, it is preferable that the laminate 25 be cooled in the cooling mechanism 17 to a temperature below the softening temperature T1 (°C) of the resin layer 20, more preferably below the glass transition temperature of the resin layer 20, even more preferably to a temperature that is 10°C or more lower than the glass transition temperature, and even more preferably to a temperature that is 20°C or more lower than the glass transition temperature. The laminate 25 may be cooled in the cooling mechanism 17 to a temperature of about room temperature (e.g., 23°C).

[0108] The cooling mechanism 17 is not particularly limited, but examples include a cooling roll and a cooling space. When a cooling roll is used, cooling is performed by moving the laminate 25 along the cooling roll after heating or warming in the annealing section 16. The cooling space is a space maintained in a low-temperature environment, and may be a space or device that maintains a temperature below that of the laminate 25 passing through, such as an air-cooled bath, a cooling chamber, or a room temperature environment. When a cooling space is used, the laminate 25 is simply passed through a cooling space adjusted to a low-temperature environment. The temperature inside the cooling space constituting the cooling mechanism 17 and the temperature of the surface of the cooling roll with which the laminate contacts, i.e., the cooling temperature, may be appropriately set so that the laminate 25 is within the above-mentioned temperature range, for example, 0°C or higher and lower than the softening temperature T1 (°C), preferably 5°C or higher and 25°C or lower. The cooling time for the laminate 25 in the cooling mechanism 17 at these temperatures is not particularly limited, but may be, for example, 0.1 to 120 seconds, preferably 0.1 to 60 seconds.

[0109] The laminate 25 cooled in the cooling mechanism 17 is wound into a roll by the winding mechanism 18, thereby obtaining a roll-shaped laminate. The winding mechanism 18 is not particularly limited, and a known winding machine may be used.

[0110] In this embodiment, the laminate 25 obtained by the above series of steps has suppressed shrinkage of the resin layer 20, and by laminating the first releasable substrate 21 and the second releasable substrate 22, dimensional changes due to residual strain in the resin layer 20 are also suppressed, making it possible to obtain a laminate 25 with high dimensional stability. Furthermore, in this embodiment, the thermoplastic resin composition (resin layer 20) extruded from the mold 12 is laminated with the first and second releasable substrates 21, 22 before being transported by rolls. Therefore, warping and other problems that occur due to roll transport are less likely to occur, making it easier to ensure the flatness of the adhesive film.

[0111] The width of the laminate 25 after cutting the edges may be adjusted before being wound by the winding mechanism 18. Furthermore, the laminate 25 may be inspected as appropriate, for example, by measuring the thickness, checking for the presence of foreign matter, measuring foreign matter such as counting the number of foreign matter and measuring its size, measuring transmittance, measuring color, etc. The edge cutting and inspection may be performed after cooling by the cooling mechanism 17 and before winding, but are preferably performed immediately before winding.

[0112] Furthermore, in the above embodiment, the moisture content of the resin layer 20 is adjusted in an extruder, but the moisture content does not have to be adjusted in an extruder. For example, the moisture content may be adjusted by a humidity control mechanism after cooling by the cooling mechanism 17. The humidity control mechanism is not particularly limited, and examples thereof include a humidity control device that maintains a constant internal humidity. For example, the moisture content of the resin layer 20 may be adjusted by passing the laminate 25 through the humidity control device. However, the humidity control device does not need to be provided separately, and the moisture content of the resin layer 20 may be adjusted by adjusting the humidity of the cooling space that constitutes the cooling mechanism to a constant value.

[0113] An embodiment of the laminate manufacturing method of the present invention is not limited to the manufacturing method using the manufacturing apparatus shown in FIG. 1 . For example, although an example has been described in which a substrate heating mechanism 14, an annealing section 16, and a cooling mechanism 17 are provided and the temperature in each mechanism or section is controlled within a predetermined range, any of these mechanisms may be omitted as appropriate. Furthermore, if the first release substrate is embossed but the second release substrate is not, the embossing roll 52 need not be provided. Furthermore, the first release substrate 21 may be transported on the first roll 35 along the first roll 35 and supplied between the first and second rolls 35, 36, and the molten thermoplastic resin composition (resin layer 20) extruded from the mold 12 may then be supplied between the first and second rolls 35, 36. The second release substrate may then be transported along the rolls on the rolls and sandwiched between the two rolls, and the second release substrate may be laminated on the adhesive film laminated with the first release substrate. Alternatively, the second releasable substrate 22 may be transported on the second roll 36 along the first roll 36 and supplied between the first and second rolls 35, 36, and then the thermoplastic resin composition (resin layer 20) extruded from the mold 12 and melted may be supplied between the first and second rolls 35, 36. The first releasable substrate may then be transported along the rolls and sandwiched between the two rolls, and the first releasable substrate may be laminated on the adhesive film laminated with the second releasable substrate. Alternatively, the laminating mechanism may include two pairs of rolls, and one of the first and second releasable substrates may be bonded to the resin layer between the first set of rolls, and then the other may be bonded to the resin layer between the second set of rolls. Alternatively, an adhesive film wound in a roll may be prepared without producing the adhesive film from the thermoplastic resin composition, and the first and second releasable substrates may be laminated onto the adhesive film unwound from the roll to produce a laminate, which may then be wound up.

[0114] <Uses of Laminate> The uses of the laminate of the present invention are not particularly limited, and the adhesive film may be used by being bonded to another adherend. The laminate of the present invention may be bonded to an adherend with the first releasable substrate still laminated on the adhesive film. Furthermore, when the laminate of the present invention has first and second releasable substrates, the second releasable substrate may be peeled off and then the adhesive film may be bonded to the adherend. The dimensional accuracy of the adhesive film of the laminate of the present invention can be further improved by peeling the first and second releasable substrates from the laminate just before bonding the laminate to the adherend, or by peeling the first releasable substrate from the laminate after bonding the laminate to the adherend.

[0115] The adherend to which the adhesive film is bonded is not particularly limited, but examples thereof include organic material substrates and inorganic material substrates. Examples of organic material substrates include organic resin plates and resin films. Organic resin plates are also called organic glass. Examples of organic glass include, but are not particularly limited to, (meth)acrylic plates such as polycarbonate plates and polymethyl methacrylate plates. The thickness of the organic glass and the inorganic glass described below (collectively sometimes referred to as glass members) is not particularly limited, but is preferably 0.1 mm or more, more preferably 1.0 mm or more, and preferably 5.0 mm or less, more preferably 3.2 mm or less.

[0116] The resin film is not particularly limited, but examples thereof include polyester resin films such as (meth)acrylic resin films, polycarbonate films, polyethylene terephthalate (PET) films, and polyethylene naphthalate (PEN) films; polyolefin resin films such as polyethylene films and polypropylene films; cyclic polyolefin (COP) films, triacetyl cellulose (TAC) films, polyethersulfone (PES) resin films, and polyimide resin films. The surface of the resin film may be provided with a surface layer such as a hard coat layer made of a (meth)acrylic resin or a coating layer containing a heat-shielding substance. The adhesive film in the laminate of the present invention may also be bonded to an adhesive film made of the thermoplastic resin composition described above. Therefore, the adhesive film of the present invention may serve as an adherend. The thickness of the resin film is not particularly limited, but is preferably 30 μm to 2 mm, more preferably 40 μm to 1 mm, and even more preferably 50 μm to 500 μm. In addition, materials that are relatively thick, have low flexibility, and generally cannot be bent are called organic resin plates, while materials that are relatively thin and generally can be bent are generally called resin films, but these are not clearly distinguished from each other.

[0117] Examples of inorganic material substrates include inorganic glass. The inorganic glass is not particularly limited, but examples include various glass plates such as float glass, tempered glass, colored glass, polished glass, patterned glass, wired glass, striped glass, ultraviolet absorbing glass, infrared reflecting glass, infrared absorbing glass, and green glass. The inorganic glass may be subjected to a surface treatment or may be provided with a surface layer such as a coating layer containing a heat-shielding substance. The adhesive film is preferably attached to the inorganic glass.

[0118] The laminate of the present invention may also be used for a functional element. The functional element may be electrically controllable. In this case, the functional element has an electrical circuit, and its operation can be switched by the flow of current or by changing the amount of current flow. Specific examples of electrically controllable functional elements include electrically controllable films and substrates such as electrically controllable flexible printed circuit boards. More specifically, examples include films or flexible printed circuit boards equipped with devices such as dimmers, coils, antennas, piezoelectric elements, LED elements, batteries, sensors such as touch sensors, switches, memories, processors, integrated circuits such as communication ICs, and display elements such as organic EL display elements and liquid crystal display elements. Furthermore, the functional element may be a glass panel in which these devices are mounted on a glass member, an image display panel in which a display element is incorporated into a glass member, or a touch panel in which a touch sensor is incorporated into a resin film or glass member. A preferred functional element is a dimmer element equipped with a dimmer. Examples of the light control element include polymer dispersed liquid crystal (PDLC), electrochromic (EC), suspended particle device (SPD), electrophoretic device, guest host liquid crystal (GHLC), etc. Furthermore, the functional element preferably includes a display element such as an organic EL display element or a liquid crystal display element.

[0119] Examples of electrically controllable films include those comprising at least a substrate film and a device provided on the substrate film, but they may also be those in which a device is disposed between two substrate films. Examples of substrate films include polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, acrylic resin films, cellulose derivative films such as triacetyl cellulose (TAC), polyethersulfone (PES) resin films, and polyimide resin films. Furthermore, in electrically controllable films, an electrode layer may be provided on the device-side surface of the substrate film. Any conventionally known electrode material may be used as the electrode layer without any particular limitation, but a transparent electrode layer is preferred.

[0120] The functional element is preferably a light-controlling film in which the device is a light-controlling body. Examples of light-controlling films include two substrate films and a light-controlling body (light-controlling layer) disposed between the two substrate films. The functional element may not be electrically controlled. Specific examples include a heat-shielding film (heat-absorbing or reflective), a color film, a polarizing plate, an optical compensation plate, or a composite. The thickness of the functional element is not particularly limited, but is, for example, about 20 μm to 2000 μm, preferably about 100 μm to 1000 μm, and more preferably about 200 μm to 800 μm. The thickness of the functional element may vary depending on the position, and in this case, the maximum thickness is meant.

[0121] The laminate of the present invention is preferably used by placing the adhesive film between two members to bond the two members, and more preferably used as an interlayer film for laminated glass by placing the adhesive film between two glass members to bond the two glass members.

[0122] Furthermore, the adhesive film in the laminate of the present invention is preferably used in an image display device, and is preferably used to bond together components constituting the image display device, such as a cover glass, a touch panel, or an image display panel. For example, when used in an image display device, the adhesive film needs to be attached to the edge of a component such as a cover glass, a touch panel, or an image display panel, so to speak, just edge. If the adhesive film protrudes from the edge of each component, that portion needs to be cut off, but cutting off the protruding portion may damage each component. By using the laminate of the present invention, the dimensional accuracy of the adhesive film can be increased, so the adhesive film can be attached to the edge of the glass plate, and there is no need to cut off the portion of the adhesive film protruding from the edge of the glass plate.

[0123] When the laminate of the present invention is used in a functional element, the adhesive film may be used to adhere the functional element to another component. Alternatively, a functional element such as a light control element may be fitted into the frame of an adhesive film formed into a frame shape to fit the functional element, and then the film may be attached to another component such as a resin film. In this case, if there is a gap between the frame of the adhesive film and the functional element, foaming may occur. However, by using the laminate of the present invention, the dimensional accuracy of the adhesive film can be improved, thereby preventing gaps from occurring between the frame of the adhesive film and the functional element.

[0124] Generally, when an adhesive film obtained by extrusion molding is thin, the dimensional stability of the thickness of the adhesive film decreases and warping occurs easily. However, the laminate of the present invention has excellent dimensional stability of the thickness and a small rate of dimensional change in the planar direction (MD or TD), and therefore the laminate of the present invention can be suitably used in applications where a thin adhesive layer is required.

[0125] The laminate of the present invention can be used for a variety of applications, including window glass for various vehicles such as automobiles and trains, ships, and airplanes, various buildings such as buildings, condominiums, detached houses, halls, and gymnasiums, machine tools for cutting and polishing, and construction machines such as shovels and cranes, and partitions inside various vehicles and buildings. Of these, applications in vehicles such as automobiles are preferred, and applications in vehicles such as laminated glass for vehicles, in-vehicle displays, and light-control roofs are more preferred.

[0126] 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.

[0127] <Peel strength between first releasable substrate and adhesive film (peel strength A)> Using an Instron "5965 type universal testing machine," a 180 ° peel test was performed in accordance with JIS K6854-2:1999 to measure the peel strength. Specifically, the laminate was cut into a width of 25 mm and a length of 150 mm. Thereafter, the second releasable substrate was peeled off, and the surface of the adhesive film from which the second releasable substrate had been peeled off was pressure-bonded to a SUS plate via a double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 501L). At this time, pressure-bonding was performed by two reciprocating strokes with a 2 kg rubber roller. The SUS plate was held with one jig of the universal testing machine, and the sample was held with the other jig, and the 180 ° peel adhesive strength was measured when peeled off at a speed of 100 mm / min at 23 ° C. The peel strength was determined as 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. The peel strength was measured twice for each sample, and the peel strengths obtained in each measurement were further averaged to determine the peel strength of that sample. The double-sided adhesive fixing tape 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 fixing tape, or at the interface between the double-sided adhesive fixing tape and the adhesive film after measurement.

[0128] <Peel strength between adhesive film and glass plate (peel strength B)> Using an Instron "5965 type universal testing machine," a 180° peel test was performed in accordance with JIS K6854-2:1999 to measure the peel strength. Specifically, the laminate was cut into a width of 25 mm and a length of 150 mm. In addition, a 3 mm thick clear float glass plate (manufactured by Central Glass Products, product number "FL 2.5") in accordance with JIS 3202 was prepared. Thereafter, the second releasable substrate was peeled off, and the surface of the adhesive film from which the second releasable substrate had been peeled was pressed onto the clear float glass plate. At this time, the pressure was applied by two reciprocating strokes with a 2 kg rubber roller. The clear float glass plate was held with one jig of the universal testing machine, and the sample was held with the other jig, and the 180° peel adhesive strength was measured when peeled off at a speed of 100 mm / min at 23 ° C. The peel strength was determined as 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. The peel strength was measured twice for each sample, and the peel strengths obtained in each measurement were further averaged to determine the peel strength of the sample.

[0129] <Surface roughness Rzjis of the release surface of the adhesive film after peeling off the second release substrate> The surface roughness Rzjis of the release surface of the adhesive film after peeling off the second release substrate was measured in accordance with JIS B-0601 (1994). Here, the measuring instrument used was a "Surfcorder SE300" manufactured by Kosaka Laboratory Co., Ltd. The cutoff value during measurement was 0.8 mm, the reference length was 0.8 mm, the measurement length was 4 mm, the preliminary length was 0.8 mm, the palpation needle feed rate was 0.5 mm / sec, and the palpation needle shape had a tip radius of 2 μm and a tip angle of 60°. The measurement was performed in an environment of 23°C and 30% RH. The laminate to be measured was left to stand in the measurement environment for at least 3 hours before measurement. The surface roughness Rzjis of the release surface of the adhesive film after peeling off the second releasable substrate was measured at three locations: the center position in the width direction of the laminate, a position 300 mm away from that center in one width direction, and a position 300 mm away from that center in the other width direction. The average value of the surface roughness Rzjis at these three locations was taken as the surface roughness Rzjis of the measured sample. When the surface roughness Rz was less than 0.2 μm, it was taken as 0 μm. When the surface roughness Rz exceeded 10 μm, the measurement was performed under the following measurement conditions: cutoff value 2.5 mm, reference length 2.5 mm, measurement length 12.5 mm, and preliminary length 2.5 mm.

[0130] <Root-mean-square slope Sdq of the release surface of the adhesive film after peeling off the second release substrate> Measurements and image processing were performed under the following conditions using a three-dimensional white light interference microscope (manufactured by BURUKER AXS, trade name "Countour GT"), and the root-mean-square slope Sdq of the release surface of the adhesive film after peeling off the second release substrate was calculated. <Measurement conditions> Measurement range: 2 mm x 2 mm, objective lens: 10x magnification, internal lens: 0.55x magnification, measured in VSI mode. <Image processing conditions> "Vision 64", the analysis software included with the device, was used. The following first to third treatments were performed as planarization treatments. That is, as the first process, a "Terms Removal (F-Operator)" process on the Analysis Toolbox was performed under the analysis condition "Tilt only (Plane Fit)." As the second process, a "Statistical Filter" process was performed under the analysis conditions "Filter type: Sigma" and "Filter size: 5." As the third process, a "data Restore" process was performed under the analysis condition "Legacy," with the RestoreEdge condition selected and the Iteration condition set to 200 (a value that allows sufficient data complementation).

[0131] <Storage modulus (G') of adhesive film at 25°C> The laminate was cut into a length of 10 mm and a width of 5 mm, the first release substrate and the second release substrate were peeled off, and the viscoelasticity of the adhesive film was measured under the following measurement conditions using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, trade name "ARES-G2"), and the storage modulus (G') was calculated. (Measurement conditions) Deformation mode: shear mode, measurement temperature: temperature decrease from 100°C to -20°C, temperature decrease rate: 3°C / min, measurement frequency: 1 Hz, strain: 1%, 8 mm parallel plate

[0132] <Visible light transmittance of adhesive film> The first releasable substrate and the second releasable substrate were peeled off from the laminate, and the solar transmittance of the adhesive film was measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by Hitachi, Ltd., product name "UH4150").

[0133] <Reworkability (Release Tape)> The laminate was cut to a width of 25 mm and a length of 150 mm. After that, the second release substrate was peeled off, and the surface of the adhesive film from which the second release substrate had been peeled was pressed against a glass plate. A release tape of 25 mm width and 30 mm length was then attached to the edge region of the first release substrate. The release tape attached to the first release substrate was gripped to peel the laminate from the glass plate. This operation was performed twice. The reworkability of the laminate was evaluated according to the following evaluation criteria. (Evaluation Criteria) A: In both attempts, the laminate could be peeled from the glass plate without the first release substrate peeling from the adhesive film. B: In one of the two attempts to peel the first release substrate, the laminate could be peeled from the glass plate without the first release substrate peeling from the adhesive film. However, in the other attempt, the first release substrate peeled from the adhesive film when peeling the laminate from the glass plate. C: When the laminate was peeled from the glass plate both times, the first releasable substrate peeled from the adhesive film.

[0134] <Reworkability (edge ​​retention)> The laminate was cut to a width of 25 mm and a length of 150 mm. Thereafter, the second releasable substrate was peeled off. Then, a portion 20 mm from the edge of the adhesive film was cut and removed. As a result, the pressure-sensitive adhesive film was 25 mm wide and 130 mm long. Thereafter, the surface of the adhesive film from which the second releasable substrate had been peeled was pressed against a glass plate. Then, the portion of the first releasable substrate where the adhesive film was not laminated was grasped, and the laminate was peeled from the glass plate. The above operation was performed twice. Then, the reworkability of the laminate was evaluated according to the following evaluation criteria. (Evaluation criteria) A: In both cases, the laminate could be peeled from the glass plate without the first releasable substrate peeling from the adhesive film. B: In one of the two peeling attempts of the first releasable substrate, the laminate could be peeled from the glass plate without the first releasable substrate peeling from the adhesive film. However, in the other case, when the laminate was peeled from the glass plate, the first releasable substrate peeled from the adhesive film. C: In both cases, when the laminate was peeled from the glass plate, the first releasable substrate peeled from the adhesive film.

[0135] The following materials were used in the examples and comparative examples. (Thermoplastic Resin) 1800 ml of ion-exchanged water and 200 g of polyvinyl alcohol A (average degree of polymerization 1700, degree of saponification 99 mol%) were placed in a reactor equipped with a stirrer, 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. The temperature was then adjusted to 15°C, and n-butylaldehyde was added to 10 mol% while stirring. Subsequently, n-butylaldehyde was added to 60 mol%, resulting in the precipitation of a white particulate polyvinyl butyral resin. Ten minutes after precipitation, 30% hydrochloric acid was added so that the hydrochloric acid concentration was 1.8% by mass. The temperature was then raised to 53°C, and the mixture was aged at this aging temperature for 2 hours. 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, hydroxyl group content 30.3 mol%, acetalization degree 68.5 mol%, acetylation degree 1.2 mol%).

[0136] The release substrates used in the Examples and Comparative Examples were as follows. Release substrate 1: PET (polyethylene terephthalate) film, manufactured by Toray Industries, Inc., trade name "Lumirror", thickness 50 μm, grade: S10, embossed (with unevenness formed to about half the depth compared to Release substrate 2). Release substrate 2: PET (polyethylene terephthalate) film, manufactured by Toray Industries, Inc., trade name "Lumirror", thickness 50 μm, grade: S10, embossed. Release substrate 3: PET (polyethylene terephthalate) film, manufactured by Toray Industries, Inc., trade name "Lumirror", thickness 75 μm, grade: T60, not embossed.

[0137] Example 1 A laminate was produced using the production apparatus 10 shown in FIG. 1. Specifically, 100 parts by mass of resin and 35 parts by mass of plasticizer (triethylene glycol-di-2-ethylhexanoate: 3GO) were supplied to an extruder 11 and melt-kneaded to produce a resin composition, and the resin composition was extruded from a mold 12 at 211 ° C. Meanwhile, first and second release substrates 21, 22 were fed from first and second feed mechanisms 31, 32. In Example 1, a release substrate 1 was used as the first release substrate 21 and the second release substrate 22. The extruded resin composition (resin layer 20) was sandwiched between two heated release substrates 21, 22 using the method shown in FIG. 2 to produce a laminate in which the resin layer (adhesive film) had a thickness of 200 μm. When the first and second substrates 21, 22 were laminated, the temperature of the cast roll 35 was 80°C, and the temperature of the nip roll 36 was 40°C, and the laminate was a laminate in which the first release substrate, the resin layer (adhesive film), and the second release substrate were laminated in this order, and the types of the first release substrate and the second release substrate in the laminate were as shown in Table 1. The laminate was wound into a roll by the winding mechanism 18, to form a roll-shaped laminate.

[0138] (Example 2) A release substrate 2 was used as the first release substrate 21 and the second release substrate 22. Specifically, 100 parts by mass of a resin and 35 parts by mass of a plasticizer (triethylene glycol-di-2-ethylhexanoate: 3GO) were supplied to an extruder 11 and melt-kneaded to prepare a resin composition, and the resin composition was extruded from a mold 12 at 211 ° C. Meanwhile, in Example 2, the first and second release substrates 21, 22 were fed from first and second feed mechanisms 31, 32, and each substrate 21, 22 was heated to 120 ° C. by a substrate heating mechanism 14 consisting of a heating roll. In Example 2, a release substrate 2 was used as the first release substrate 21 and the second release substrate 22. The extruded resin composition (resin layer 20) was sandwiched between two heated releasable substrates 21 and 22 by the method shown in Figure 2, and a laminate having a resin layer (adhesive film) thickness of 200 μm was produced. In Example 2, when laminating the first and second substrates 21 and 22, the temperature of the cast roll 35 was 120 ° C., the temperature of the nip roll 36 was 60 ° C., and the laminate was a laminate in which the first releasable substrate, the resin layer (adhesive film), and the second releasable substrate were laminated in this order, and the types of the first releasable substrate and the second releasable substrate in the laminate were substrate 1 as shown in Table 1. The laminate was wound into a roll by the winding mechanism 18 to produce a roll-shaped laminate.

[0139] Example 3 A laminate of Example 3 was produced in the same manner as in Example 1, except that the thickness of the resin layer was changed from 200 μm to 380 μm.

[0140] Example 4 A laminate of Example 4 was produced in the same manner as in Example 2, except that the thickness of the resin layer was changed from 200 μm to 380 μm.

[0141] Comparative Example 1 A laminate of Comparative Example 1 was produced in the same manner as in Example 2, except that the release substrate 3 was used as the first release substrate 21 and the second release substrate 22.

[0142] Comparative Example 2 A laminate of Example 4 was produced in the same manner as in Comparative Example 1, except that the thickness of the resin layer was changed from 200 μm to 380 μm.

[0143] The evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

[0144] The laminates of Examples 1 to 4 had a peel strength ratio (A / B) of 4 or more, and therefore were able to prevent the first releasable substrate from peeling from the adhesive film during rework of the laminate. On the other hand, the laminates of Comparative Examples 1 and 2 had a peel strength ratio (A / B) of less than 4, and therefore were unable to prevent the first releasable substrate from peeling from the adhesive film during rework of the laminate.

[0145] REFERENCE SIGNS LIST 10 Manufacturing apparatus 11 Extruder 12 Mold 13 Feed-out mechanism 14 Substrate heating mechanism 15 Laminating mechanism 16 Annealing section 17 Cooling mechanism 18 Winding mechanism 20 Resin layer 21, 22 Substrate 25 Laminate 31 First feed-out mechanism 32 Second feed-out mechanism 35 First roll 36 Second roll 41 Pinch roll 42, 43 Guide rolls 51, 52 Embossing roll

Claims

1. A laminate comprising an adhesive film and a first releasable substrate provided on one side of the adhesive film, wherein the peel strength between the first releasable substrate and the adhesive film is A (N / 25 mm), and the peel strength between the adhesive film and a glass plate when the adhesive film is attached to the side of the adhesive film opposite to the side in contact with the first releasable substrate is B (N / 25 mm), and the peel strength between the adhesive film and the glass plate is B (N / 25 mm). The laminate has a peel strength ratio (A / B) of 4 or more.

2. The laminate according to claim 1, wherein the peel strength A is 0.5 N / 25 mm or more and 10 N / 25 mm or less.

3. The laminate according to claim 1, wherein the peel strength B is 0.1 N / 25 mm or more and 2.5 N / 25 mm or less.

4. The laminate according to claim 1, wherein the adhesive film has a storage modulus (G') at 25°C of 3 MPa or more and 11.3 MPa or less.

5. The laminate according to claim 1, wherein the adhesive film is made of a thermoplastic resin composition containing a thermoplastic resin.

6. The laminate according to claim 1, wherein the root mean square slope Sdq of the release surface of the adhesive film after the first releasable substrate has been peeled off is 3 or more and 20 or less.

7. The laminate according to claim 1, wherein the surface roughness Rzjis of the release surface of the adhesive film after the first releasable substrate has been peeled off is 3 μm or more and 10 μm or less.

8. The laminate according to claim 1, wherein the first release substrate is at least one substrate selected from the group consisting of release film, release paper, mesh material, metal, and prepreg, and the resin constituting the release film is polyester resin, polyolefin resin, polyimide resin, fluororesin such as tetrafluoroethylene, silicone resin, liquid crystal polymer, polysulfone resin, cellulose acetate, polyamide resin, polyether ether ketone resin, polyether ketone ketone resin, modified polyphenylene ether, polyphenylene sulfide resin, polycarbonate resin, or polybenzimidazole resin.

9. The laminate according to claim 1, wherein, in a plan view, at least a portion of the periphery of said first releasable substrate extends outward relative to the periphery of said adhesive film.

10. The laminate according to claim 1, further comprising a second releasable substrate provided on the other side of said adhesive film.

11. A laminate according to claim 10, wherein, when the peel strength between the second releasable substrate and the adhesive film is C (N / 25 mm), the peel strength C is smaller than the peel strength A.

12. A laminate according to claim 10, wherein the second release substrate is at least one substrate selected from the group consisting of release films, release papers, mesh materials, metals, and prepregs, and the resin constituting the release film is polyester resin, polyolefin resin, polyimide resin, fluororesin such as tetrafluoroethylene, silicone resin, liquid crystal polymer, polysulfone resin, cellulose acetate, polyamide resin, polyether ether ketone resin, polyether ketone ketone resin, modified polyphenylene ether, polyphenylene sulfide resin, polycarbonate resin, or polybenzimidazole resin.

13. The laminate according to claim 8, wherein, in a plan view, at least a portion of the outer periphery of the second releasable substrate extends outward relative to the outer periphery of the adhesive film.

14. The laminate according to claim 1, wherein the surface roughness Rzjis of the surface of said adhesive film opposite to the surface in contact with said first releasable substrate is 3 μm or more and 10 μm or less.

15. The laminate according to claim 1, wherein the visible light transmittance of the adhesive film after all releasable substrates have been peeled from the laminate is less than 90%.

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