Heat-welding film and bonded body using the same

Abstract

To provide a heat-welding film to ensure sufficient bonding strength even in a method for welding through a heat-welding film and to provide a related technique.SOLUTION: A heat-welding film consists of three or more layers including a core film, and two organic layers forming outermost layers. The organic layer is at least one selected from the group consisting of a polymer layer composed of a polymer of a polymerizable composition including at least one of the following (1)-(13) and a polymer layer composed of a polymer of a polymerizable composition including at least one of the following (1)-(13) and the following (14).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-weldable film suitable for easily and firmly welding the same or different types of substrates, a method for producing the same, a bonded body using the heat-weldable film, and a method for producing the same. [Background technology]

[0002] In recent years, from the perspective of reducing product weight and improving performance, the use of multi-material components has been progressing in various fields, such as automobile parts, medical equipment, and home appliances. This has created a need for technologies to join dissimilar materials, such as resin, metal, and CFRP.

[0003] The methods used to join dissimilar materials include mechanical joining, adhesive joining, and welding. Of these, welding is a particularly reliable and productive joining method. Welding is a technique that joins materials by heating them to above their melting point, applying pressure, and cooling them. Conventional welding methods include ultrasonic welding, vibration welding, heat welding, hot air welding, and induction welding.

[0004] Welding is a common joining method used to join similar thermoplastic resin materials, but depending on the welding method and the type of resin, the resulting joint strength may not be sufficient. Due to damage to the base material during welding, the resulting joint strength is often only 50-80% of the original base material strength. For this reason, improvements to welding methods are being made.

[0005] As an improved welding method, there is a technique of joining substrates via a heat-weldable film. For example, Patent Document 1 discloses a heat-weldable film made of a modified polyolefin resin composition, which is a heat-weldable film that enables adhesion of polyolefin resins, which have poor adhesive properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-210842 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technique of Patent Document 1 has a problem in that the strength of the heat-weldable film made of the modified polyolefin resin composition itself is low, and therefore sufficient bonding strength cannot be achieved.

[0008] The present invention has been made in view of the above technical background, and aims to provide a heat-sealable film and related technologies that ensure sufficient bonding strength even in a method of welding via the heat-sealable film. The related technologies mean a method for manufacturing a heat-sealable film, a bonded body using the heat-sealable film, and a method for manufacturing the same. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides the following means. In this specification, "bonding" means joining two objects together, and adhesion and welding are subordinate concepts. Adhesion means joining two adherends (objects to be bonded) together using an organic material such as tape or adhesive (thermosetting resin, thermoplastic resin, etc.), and welding means melting the surface of the adherend, such as thermoplastic resin, by heat, and joining the two objects by entanglement and crystallization caused by molecular diffusion through contact pressure and cooling.

[0010] <Heat-welding film> [1] It consists of three or more layers, The optical fiber has a core film and organic layers laminated on both sides of the core film, A heat-sealable film, wherein the organic layer is at least one selected from the group consisting of a polymer layer made of a polymer of a polymerizable composition containing at least one of the following (1) to (13), and a polymer layer made of a polymer of a polymerizable composition containing at least one of the following (1) to (13) and the following (14): (1) Combination of difunctional isocyanate compound and diol (2) Combination of a bifunctional isocyanate compound and a bifunctional amino compound (3) Combination of a bifunctional isocyanate compound and a bifunctional thiol compound (4) Combination of a difunctional epoxy compound and a diol (5) Combination of a difunctional epoxy compound and a difunctional carboxy compound (6) Combination of a bifunctional epoxy compound and a bifunctional thiol compound (7) Monofunctional radical polymerizable monomer (8) A combination of a bifunctional epoxy compound and at least one of a phenol novolac resin and a cresol novolac resin (9) A combination of at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin with a bifunctional phenol compound (10) A combination of a bifunctional thiol compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (11) A combination of a bifunctional amino compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (12) A combination of a bifunctional carboxy compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (13) A combination of a bifunctional isocyanate compound and at least one of a phenol novolac resin and a cresol novolac resin. (14) At least one of maleic anhydride modified polyolefin and chlorinated polyolefin [2] The heat-sealable film according to [1], wherein the organic layer is at least one polymer layer selected from the group consisting of a polymer layer formed by polymerizing a polymerizable composition containing at least one of (1) to (13) on the core film, and a polymer layer formed by polymerizing a polymerizable composition containing at least one of (1) to (13) and the following (14) on the core film: [3] The heat-sealable film according to [1] or [2], wherein the core film is a resin film made of at least one resin selected from the group consisting of polyvinyl chloride, polyphenylene sulfide, polyethylene terephthalate, nylon, polyvinylidene chloride, and polyimide. [4] The heat-weldable film according to [1] or [2], wherein the core film is an inorganic foil made of at least one material selected from the group consisting of aluminum, copper, and glass. <Method for manufacturing heat-sealable film> [5] A method for producing a heat-sealable film having a layer structure of three or more layers, the film having a core film and heat-sealable organic layers laminated on both sides of the core film, comprising: A method for producing a heat-sealable film, comprising polymerizing, on the core film, at least one polymerizable composition selected from the group consisting of a polymerizable composition containing at least one of the following (1) to (13), and a polymerizable composition containing at least one of the following (1) to (13) and the following (14), to form the organic layer: (1) Combination of difunctional isocyanate compound and diol (2) Combination of a bifunctional isocyanate compound and a bifunctional amino compound (3) Combination of a bifunctional isocyanate compound and a bifunctional thiol compound (4) Combination of a difunctional epoxy compound and a diol (5) Combination of a difunctional epoxy compound and a difunctional carboxy compound (6) Combination of a bifunctional epoxy compound and a bifunctional thiol compound (7) Monofunctional radical polymerizable monomer (8) A combination of a bifunctional epoxy compound and at least one of a phenol novolac resin and a cresol novolac resin (9) A combination of at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin with a bifunctional phenol compound (10) A combination of a bifunctional thiol compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (11) A combination of a bifunctional amino compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (12) A combination of a bifunctional carboxy compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (13) A combination of a bifunctional isocyanate compound and at least one of a phenol novolac resin and a cresol novolac resin (14) At least one of maleic anhydride modified polyolefin and chlorinated polyolefin [6] the polymerization is carried out on the surface-treated side of the core film; The method for producing a heat-weldable film according to [5], wherein the surface treatment is at least one selected from the group consisting of plasma treatment, corona discharge treatment, UV ozone treatment, blast treatment, polishing treatment, etching treatment and chemical conversion treatment. [7] The method for producing a heat-weldable film according to [5] or [6], wherein before forming the organic layer, the core film is treated with a solution containing at least one selected from the group consisting of the following (c1) to (c7), thereby providing functional groups on the surface of the core film: (c1) a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group. (c2) a silane coupling agent having an amino group and at least one compound selected from the group consisting of an epoxy compound and a thiol compound (c3) a silane coupling agent having a mercapto group and at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group; (c4) A silane coupling agent having a (meth)acryloyl group and a thiol compound (c5) a silane coupling agent having an epoxy group and at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having a (meth)acryloyl group and an amino group; (c6) Isocyanate compounds (c7) Thiol compounds <zygote> [8] A bonded body obtained by joining a first substrate made of one material selected from the group consisting of metals, resins, ceramics, and glass to a second substrate made of one material selected from the group consisting of metals, resins, ceramics, and glass by welding via the heat-welding film according to any one of [1] to [4]. <Method of manufacturing the bonded body> [9] A method for producing a bonded body, comprising welding a first substrate made of one material selected from the group consisting of metals, resins, ceramics, and glass to a second substrate made of one material selected from the group consisting of metals, resins, ceramics, and glass via the heat-welding film according to any one of [1] to [4], thereby integrally bonding the first substrate and the second substrate.

[10] The welding is performed by at least one method selected from the group consisting of ultrasonic welding, vibration welding, electromagnetic induction, high frequency welding, laser welding, and heat pressing. [9] A method for producing the bonded body according to claim 1. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a heat-weldable film suitable for applications in which substrates are firmly welded together, and related techniques thereof. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an explanatory diagram showing the configuration of a heat-weldable film according to one embodiment of the present invention. [Figure 2]1 is an explanatory diagram showing a configuration of a bonded body according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The heat-weldable film of the present invention and related art will now be described in detail. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate. In this specification, a polymerizable composition refers to a composition that forms a thermoplastic structure, i.e., a linear polymer structure, by a polyaddition reaction of a combination of specific bifunctional compounds in the presence of a catalyst, or by a radical polymerization reaction of specific monofunctional monomers. Unlike thermosetting resins that form a three-dimensional network with a crosslinked structure upon polymerization, a polymerizable composition hardly forms a three-dimensional network with a crosslinked structure and has thermoplastic properties.

[0014] [Heat-welding film] 1, the heat-sealable film 1 of this embodiment has a three-layer structure, with organic layers 3 on both sides of a core film 2. The organic layers 3 have the function of making the heat-sealable film heat-sealable. The layer structure of the heat-sealable film 1 of the present invention is not limited to three layers, and may be three or more layers including at least a core film 2 and an organic layer 3 as the outermost layer (i.e., the outermost surface of the heat-sealable film 1). The organic layer constituting one outermost layer and the organic layer constituting the other outermost layer may each be a polymer layer of a different polymerizable composition.

[0015] <Core film> The core film can be any existing film, such as polyvinyl chloride, polyphenylene sulfide, polyethylene terephthalate, nylon, polyvinylidene chloride, polyimide, polycarbonate, polyethersulfone, polyetheretherketone, polyethylene, polypropylene, polyethylene naphthalate, polystyrene, polyvinyl alcohol, polymethyl methacrylate, or ethylene-vinyl alcohol. The core film is preferably a resin film made of at least one resin selected from the group consisting of polyimide, polyphenylene sulfide, nylon, polyethylene terephthalate, polyvinyl chloride, and polyvinylidene chloride. By selecting at least one selected from the group consisting of polyimide, polyphenylene sulfide, and nylon, heat resistance can be improved. By selecting at least one selected from the group consisting of polyethylene terephthalate and polyvinyl chloride, strength can be improved. By selecting polyvinylidene chloride, flexibility can be improved, and conformability to the substrate can be improved. The core film may be an inorganic foil made of at least one material selected from the group consisting of aluminum, copper, and glass. The thickness of the core film is preferably 1 to 1000 μm, more preferably 5 to 500 μm, and even more preferably 5 to 250 μm.

[0016] <Organic layer> The organic layer 3 is at least one selected from the group consisting of a polymer layer made of a polymer of a polymerizable composition containing at least one of the following (1) to (13), and a polymer layer made of a polymer of a polymerizable composition containing at least one of the following (1) to (13) and the following (14): (1) Combination of difunctional isocyanate compound and diol (2) Combination of a bifunctional isocyanate compound and a bifunctional amino compound (3) Combination of a bifunctional isocyanate compound and a bifunctional thiol compound (4) Combination of a difunctional epoxy compound and a diol (5) Combination of a difunctional epoxy compound and a difunctional carboxy compound (6) Combination of a bifunctional epoxy compound and a bifunctional thiol compound (7) Monofunctional radical polymerizable monomer (8) A combination of a bifunctional epoxy compound and at least one of a phenol novolac resin and a cresol novolac resin (9) A combination of at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin with a bifunctional phenol compound (10) A combination of a bifunctional thiol compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (11) A combination of a bifunctional amino compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (12) A combination of a bifunctional carboxy compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin (13) A combination of a bifunctional isocyanate compound and at least one of a phenol novolac resin and a cresol novolac resin (14) At least one of maleic anhydride modified polyolefin and chlorinated polyolefin

[0017] In this specification, the term "comprises" in the expression "a polymerizable composition comprising at least one of (1) to (13)" means that at least one of (1) to (13) is blended as a composition raw material of the polymerizable composition. The term "comprises" in the expression "a polymerizable composition comprising at least one of (1) to (13) and (14)" means that a combination of at least one of (1) to (13) and further (14) is blended as a composition raw material of the polymerizable composition.

[0018] The blending ratio of the bifunctional isocyanate compound to the diol in (1) is preferably set so that the molar equivalent ratio of isocyanate groups to hydroxyl groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional isocyanate compound and the bifunctional amino compound in (2) is preferably set so that the molar equivalent ratio of isocyanate groups to amino groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional isocyanate compound and the bifunctional thiol compound in (3) is preferably set so that the molar equivalent ratio of isocyanate groups to thiol groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional epoxy compound to the diol in (4) is preferably set so that the molar equivalent ratio of epoxy groups to hydroxyl groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional epoxy compound and the bifunctional carboxy compound in (5) is preferably set so that the molar equivalent ratio of epoxy groups to carboxy groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional epoxy compound and the bifunctional thiol compound in (6) is preferably set so that the molar equivalent ratio of epoxy groups to thiol groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The monofunctional radical polymerizable monomer in (7) is one or more types. The blending ratio of the bifunctional epoxy compound to at least one of the phenol novolac resin and the cresol novolac resin in (8) is preferably set so that the molar equivalent ratio of hydroxyl groups to epoxy groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of at least one of the phenol novolac epoxy resin and the cresol novolac epoxy resin to the bifunctional phenol compound in (9) is preferably set so that the molar equivalent ratio of hydroxyl groups to epoxy groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional thiol compound in (10) to at least one of the phenol novolac epoxy resin and the cresol novolac epoxy resin is preferably set so that the molar equivalent ratio of epoxy groups to thiol groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional amino compound in (11) to at least one of the phenol novolac epoxy resin and the cresol novolac epoxy resin is preferably set so that the molar equivalent ratio of epoxy groups to amino groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional carboxy compound in (12) to at least one of the phenol novolac epoxy resin and the cresol novolac epoxy resin is preferably set so that the molar equivalent ratio of epoxy groups to carboxyl groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3. The blending ratio of the bifunctional isocyanate compound to at least one of the phenol novolac resin and the cresol novolac resin in (13) is preferably set so that the molar equivalent ratio of hydroxyl groups to isocyanate groups is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.

[0019] An organic layer, which is a polymer layer made of a polymer of a polymerizable composition containing (14) and at least one of (1) to (13), is particularly effective for bonding to polyolefins. The blend ratio of at least one of maleic anhydride-modified polyolefin and chlorinated polyolefin in the polymerizable composition containing (14) and at least one of (1) to (13) is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, and even more preferably 15 to 85% by mass.

[0020] (Difunctional isocyanate compound) The bifunctional isocyanate compound is a compound having two isocyanate groups, and examples thereof include diisocyanate compounds such as hexamethylene diisocyanate (HDI), tetramethylene diisocyanate, dimer acid diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI) or a mixture thereof, p-phenylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate (MDI).

[0021] (diol) The diol is a compound having two hydroxy groups, and examples thereof include aliphatic glycols such as ethylene glycol, propylene glycol, diethylene glycol, and 1,6-hexanediol, and bisphenols such as bisphenol A, bisphenol F, and bisphenol S. Among these, propylene glycol, diethylene glycol, and the like are preferred from the viewpoint of the toughness of the primer.

[0022] (Bifunctional amino compounds) The bifunctional amino compound is a compound having two amino groups, and examples thereof include bifunctional aliphatic diamines and aromatic diamines. Examples of aliphatic diamines include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-diaminobutane, 1,6-hexamethylenediamine, 2,5-dimethyl-2,5-hexanediamine, 2,2,4-trimethylhexamethylenediamine, isophoronediamine, bis(4-amino-3-methylcyclohexyl)methane, 1,3-diaminocyclohexane, and N-aminoethylpiperazine. Examples of aromatic diamines include diaminodiphenylmethane and diaminodiphenylpropane. Among these, 1,3-propanediamine, 1,4-diaminobutane, and 1,6-hexamethylenediamine are preferred from the viewpoint of primer toughness.

[0023] (Bifunctional thiol compounds) The bifunctional thiol compound is a compound having two mercapto groups in the molecule, and examples thereof include 1,4-bis(3-mercaptobutyryloxy)butane, a bifunctional secondary thiol compound (for example, KarenzMT (registered trademark) BD1 manufactured by Showa Denko K.K.).

[0024] (Difunctional epoxy compound) The bifunctional epoxy compound is a compound having two epoxy groups in one molecule, and examples thereof include aromatic epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, biphenol epoxy resin, and naphthalene bifunctional epoxy resin, and aliphatic epoxy compounds such as 1,6-hexanediol diglycidyl ether. Among these, one type may be used alone, or two or more types may be used in combination. Specific examples include Mitsubishi Chemical Corporation's "jER (registered trademark) 828," "jER (registered trademark) 834," "jER (registered trademark) 1001," "jER (registered trademark) 1004," and "jER (registered trademark) YX-4000." Other bifunctional epoxy compounds with special structures can also be used. One of these may be used alone, or two or more may be used in combination.

[0025] (Bifunctional carboxy compound) The bifunctional carboxy compound may be any compound having two carboxy groups, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, isophthalic acid, terephthalic acid, etc. Among these, isophthalic acid, terephthalic acid, adipic acid, etc. are preferred from the viewpoint of the strength and toughness of the primer.

[0026] (Monofunctional radical polymerizable monomer) The monofunctional radical polymerizable monomer is a monomer having one ethylenically unsaturated bond. Examples include styrene monomers, α-, o-, m-, and p-alkyl, nitro, cyano, amide, and ester derivatives of styrene, chlorostyrene, vinyltoluene, and divinylbenzene; and (meth)acrylic acid esters such as ethyl (meth)acrylate, methyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofuryl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, and glycidyl (meth)acrylate. One or more of the above compounds may be used. Among these, from the viewpoint of the strength and toughness of the primer, one or a combination of two or more of styrene, methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and phenoxyethyl (meth)acrylate is preferred. In order to allow the radical polymerization reaction to proceed sufficiently and form a layer derived from the desired film, the composition may contain a solvent and, if necessary, additives such as a colorant. In this case, it is preferable that the monofunctional radically polymerizable monomer is the main component among the components contained in the radically polymerizable composition other than the solvent. The main component means that the content of the monofunctional radically polymerizable monomer is 50 to 100% by mass. The content is preferably 60% by mass or more, more preferably 80% by mass or more. Suitable polymerization initiators for radical polymerization reactions include, for example, known organic peroxides and photoinitiators. Room-temperature radical polymerization initiators obtained by combining an organic peroxide with a cobalt metal salt or an amine may also be used. Examples of organic peroxides include those classified as ketone peroxides, peroxyketals, hydroperoxides, diallyl peroxides, diacyl peroxides, peroxyesters, and peroxydicarbonates. It is desirable to use photoinitiators that can initiate polymerization using ultraviolet to visible light. The radical polymerization reaction is preferably carried out by heating for 5 to 90 minutes at room temperature to 200° C., depending on the type of reactive compound, etc. In the case of photocuring, the polymerization reaction is carried out by irradiating with ultraviolet light or visible light.

[0027] (phenol novolac resin, cresol novolac resin) Specific examples of the phenol novolak resin include BRG-555, BRG-556, BRG-557, BRG-558, and CRG-951 (all manufactured by Aica Kogyo Co., Ltd.). Examples of cresol novolac resins include ortho-, meta-, and para-cresol novolacs, such as meta-para-cresol novolac LF-100, LF-110, and LF-120, ortho-cresol novolac LF-200, and para-cresol novolac LF-400 (all manufactured by Lignite Corporation).

[0028] (Bifunctional phenolic compounds) A bifunctional phenol compound is a compound having two phenolic hydroxyl groups in the molecule. Examples include various bisphenol compounds such as bisphenol A, bisphenol F, bisphenol S, bisphenol AF, 4,4'-(1-methylethylidene)bis(2-methylphenol), 4,4'-(1,3-dimethylbutylden)bisphenol, and bisphenolfluorene (manufactured by Osaka Gas Chemicals Co., Ltd.), and various biphenol compounds such as 4,4'-dihydroxydiphenyl. These compounds may be used alone or in combination of two or more.

[0029] (phenol novolac epoxy resin, cresol novolac epoxy resin) The phenol novolac epoxy resin in the phenol novolac epoxy resin and / or cresol novolac epoxy resin and bifunctional phenol compound may be a known phenol novolac epoxy resin, such as YDPN-638 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) or N-740 (manufactured by DIC Corporation). Known cresol novolac epoxy resins can also be used, including, for example, YDCN-700-7, YDCN-700-10, YDCN-704, and YDCN-704L (all manufactured by Nippon Steel Chemical & Material Co., Ltd.), N-680 (manufactured by DIC Corporation), and CNE-202 (manufactured by Changchun Group) as o-cresol novolac epoxy resins.

[0030] (Maleic anhydride modified polyolefin, chlorinated polyolefin) Examples of maleic anhydride-modified polyolefins include maleic anhydride-modified polypropylenes, which are polypropylenes graft-modified with maleic anhydride. Examples include Kayabrid 002PP, 002PP-NW, 003PP, and 003PP-NW manufactured by Kayaku Akzo Co., Ltd., and the Modic (registered trademark) series manufactured by Mitsubishi Chemical Corporation. Furthermore, SCONA TPPP2112GA, TPPP8112GA, and TPPP9212GA manufactured by BYK Co. may be used in combination as polypropylene additives functionalized with maleic anhydride. Examples of chlorinated polyolefins include Hardlen (registered trademark) 13-LP, 13-LLP, and 15-LP manufactured by Toyobo Co., Ltd., and Superchlor (registered trademark) 814HS, 390S, 803LT (toluene solution), 803L (toluene solution), and 1026 (toluene solution) manufactured by Nippon Paper Industries Co., Ltd.

[0031] The organic layer 3 (polymer layer made of a polymer of a polymerizable composition) in the present invention is composed of multiple compounds, and it is common technical knowledge for those skilled in the art that various complex reactions can occur with the involvement of multiple functional groups depending on the compounding ratio of these multiple compounds, reaction conditions, etc. For this reason, it is impossible or impractical with current technology to directly identify and comprehensively describe the specific chemical structure or properties of a polymer layer made of a polymer of a polymerizable composition. Therefore, in the present invention, the polymer layer is specified by the composition of the composition raw materials that form the polymer layer.

[0032] <Formation of organic layer> The organic layer 3 is preferably formed on the core film 2 by polymerizing at least one polymerizable composition selected from the group consisting of a polymerizable composition containing at least one of the above (1) to (13) and a polymerizable composition containing at least one of the above (1) to (13) and the following (14): When the heat-sealable film 1 has a three-layer structure (organic layer 3 / core film 2 / organic layer 3), the organic layer 3 is preferably formed on the surface of the core film 2 by polymerizing at least one polymerizable composition selected from the group consisting of a polymerizable composition containing at least one of the above (1) to (13) and a polymerizable composition containing at least one of the above (1) to (13) and the following (14): When the heat-sealable film 1 has a layer structure of four or more layers (for example, organic layer 3 / lower layer in contact with the organic layer / core film 2 / lower layer in contact with the organic layer / organic layer 3), the organic layer 3 is preferably formed by polymerizing at least one polymerizable composition selected from the group consisting of a polymerizable composition containing at least one of (1) to (13) above and a polymerizable composition containing at least one of (1) to (13) above and the following (14) on the surface of the organic layer 3 and the lower layer in contact with the organic layer of the core film 2.

[0033] The organic layer 3 is a polymerizable composition containing at least one of the above (1) to (6) and (8) to (13) other than the above (7), and can be obtained by subjecting the polymerizable composition to a polyaddition reaction in the presence of a catalyst. Suitable catalysts for the polyaddition reaction include, for example, triethylamine, tertiary amines such as 2,4,6-tris(dimethylaminomethyl)phenol, and phosphorus compounds such as triphenylphosphine. The polyaddition reaction is preferably carried out by heating at room temperature to 200°C for 5 to 120 minutes, although this depends on the composition of the composition. The organic layer 3 is preferably integrated with the core film 2 by a method of polyaddition-reacting a polymerizable composition containing at least one of (1) to (6) and (8) to (13) on the surface of the core film 2 (so-called in-situ polymerization). A bonded structure in which substrates are bonded via a heat-sealable film obtained by polyaddition-reacting the polymerizable composition on the surface of the core film 2 exhibits particularly excellent bonding strength. While the details of the mechanism are unclear, it is presumed that the main factors are the formation of some kind of chemical bond at the interface between the organic layers 3 on both sides of the heat-sealable film 1 and each substrate, and the formation of some kind of chemical bond at the interface between the core film 2 and the organic layer 3 of the heat-sealable film. However, with current technology, it is impossible or impractical to distinguish the bonded structure or the heat-sealable film from those not produced by in-situ polymerization by specifying their specific chemical structure, the state or properties of the interface. The organic layer 3 is preferably prepared by applying a solution of a polymerizable composition containing at least one of the above (1) to (6) and (8) to (13) dissolved in a solvent to both surfaces of the core film, and then polymerizing the composition by heating or the like after the solvent has evaporated.

[0034] The organic layer 3 can also be obtained by subjecting a polymerizable composition containing the above-mentioned (7) to a radical polymerization reaction. The radical polymerization reaction is preferably carried out by heating at room temperature to 200°C for 5 to 90 minutes, although this depends on the composition of the composition. In the case of photocuring, the polymerization reaction is carried out by irradiating with ultraviolet light or visible light. The organic layer 3 can also be formed by disposing an organic layer made of a polymer of a polymerizable composition containing the monofunctional radical polymerizable monomer (7) on both sides of the core film. The organic layer 3 is preferably prepared by applying the raw materials for the organic layer directly or in a solution dissolved in a solvent to both sides of the core film, and polymerizing the raw materials by heating or the like after the solvent has evaporated.

[0035] <Surface treatment> The core film 2 forming the organic layer 3 preferably has a surface that has been surface-treated.

[0036] The surface treatment improves the adhesion of the organic layer 3 to the surface of the core film by cleaning the surface of the core film, generating hydroxyl groups on the surface, or by forming fine irregularities (roughening) on ​​the surface, thereby providing an anchoring effect.

[0037] The surface treatment is preferably any one of plasma treatment, corona discharge treatment, and UV ozone treatment from the viewpoint of generating hydroxyl groups on the surface. The hydroxyl groups generated by the surface treatment serve as starting points for imparting functional groups to the surface of the core film by the functional group imparting treatment described below. When the core film is a glass foil, the surface treatment is one of the surface cleaning methods for removing organic impurities from the surface. When the core film is a metal foil such as aluminum or copper, surface treatments such as cleaning with a solvent, degreasing, blasting, and polishing such as sanding are effective. When the core film is aluminum, etching with caustic soda or the like and boehmite treatment are particularly effective. The surface properties of the core film surface-treated by the above-mentioned method may change from those immediately after the surface treatment due to the formation of an organic layer, etc. on the surface-treated surface. For this reason, it is impossible or impractical with current technology to specifically describe the surface properties of the surface-treated core film in the heat-weldable film of the present invention. The various surface treatments can be carried out by known methods, and specific examples of the treatment methods include the following.

[0038] (Plasma treatment) The plasma treatment involves creating a plasma beam using a high-voltage power supply and a rod, which is then struck against the surface of the material to excite the molecules and put them into a functional state. Examples of such a method include atmospheric pressure plasma treatment, which can impart hydroxyl groups or polar groups to the surface of the material.

[0039] (Corona discharge treatment) The corona discharge treatment is a method used to modify the surface of a polymer film, in which electrons emitted from an electrode cleave the polymer main chain or side chain of the polymer surface layer, generating radicals that generate hydroxyl groups or polar groups on the surface.

[0040] (UV ozone treatment) UV ozone treatment is a method of cleaning or modifying surfaces using the energy of short-wavelength ultraviolet light emitted from a low-pressure mercury lamp and the power of the ozone (O3) that is generated by it. In the case of glass, it is a surface cleaning method that removes organic impurities from the surface. Equipment that uses low-pressure mercury lamps is generally called a "UV ozone cleaner," "UV cleaning equipment," or "UV surface modification equipment."

[0041] (Cleaning and degreasing treatment) Examples of the cleaning or degreasing treatment using a solvent or the like include a method in which the surface of the core film is degreased by washing or wiping with an organic solvent such as acetone or toluene.

[0042] (blasting) Examples of the blasting treatment include shot blasting and sand blasting.

[0043] (Polishing process) Examples of the polishing treatment include buff polishing using a polishing cloth, roll polishing using abrasive paper (sandpaper), and electrolytic polishing.

[0044] (etching process) When the core film is made of aluminum, examples of the etching treatment include chemical etching treatments such as the alkali method, phosphoric acid-sulfuric acid method, fluoride method, chromic acid-sulfuric acid method, and iron chloride method, as well as electrochemical etching treatments such as electrolytic etching.

[0045] When the core film is made of aluminum, the etching treatment is preferably an alkali method using an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution, and particularly preferably a caustic soda method using an aqueous sodium hydroxide solution. The alkali method can be carried out, for example, by immersing the aluminum foil in an aqueous solution of sodium hydroxide or potassium hydroxide with a concentration of 3 to 20% by mass at 20 to 70°C for 1 to 15 minutes. Additives such as chelating agents, oxidizing agents, and phosphates may be added. After the immersion, it is preferable to neutralize (desmut) the foil with a 5 to 20% by mass aqueous solution of nitric acid, rinse with water, and dry it.

[0046] (chemical conversion treatment) The chemical conversion treatment is mainly to form a chemical conversion film on the surface of the core film. When the core film is made of aluminum, examples of the chemical conversion treatment that can be carried out include boehmite treatment and zirconium treatment, with boehmite treatment being particularly preferred. It is also preferable that the chemical conversion treatment is carried out after the etching treatment.

[0047] The boehmite treatment is carried out, for example, by treating an aluminum foil with hot water at about 90 to 100°C, forming a boehmite (aluminum hydrate oxide) film on the surface of the aluminum foil. Ammonia, triethanolamine, or the like may be added to the water as a reaction accelerator. For example, the boehmite treatment can be carried out by immersing the aluminum foil in hot water at 90 to 100°C containing triethanolamine at a concentration of 0.1 to 5.0% by mass for 3 seconds to 5 minutes. In the boehmite treatment, in order to form a good boehmite film, it is preferable to bake the material after the treatment with hot water or the like.

[0048] The zirconium treatment is carried out, for example, by immersing an aluminum foil in a solution containing a zirconium salt such as zirconium phosphate, and a film of a zirconium compound is formed on the surface of the aluminum foil. For example, the zirconium treatment can also be carried out by immersing the aluminum foil in a solution of a zirconium treatment chemical conversion agent such as "Palcoat 3762" or "Palcoat 3796" (both manufactured by Nihon Parkerizing Co., Ltd.) at 45 to 70°C for 0.5 to 3 minutes.

[0049] When the aluminum foil is subjected to a surface treatment, the surface treatment preferably includes one or more treatments selected from an etching treatment and a boehmite treatment.

[0050] (Functional group imparting treatment) The core film 2 on which the organic layer 3 is to be formed is preferably subjected to a treatment to provide functional groups prior to the formation of the organic layer 3 . It is preferable to provide the surface of the core film 2 with at least one functional group selected from the group consisting of the following (C1) to (C7) by the functional group providing treatment. (C1) At least one functional group derived from a silane coupling agent and selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group. (C2) A functional group generated by the reaction of an amino group derived from a silane coupling agent with at least one compound selected from the group consisting of epoxy compounds and thiol compounds. (C3) A functional group formed by the reaction of a mercapto group derived from a silane coupling agent with at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group. (C4) A functional group generated by the reaction of a (meth)acryloyl group derived from a silane coupling agent with a thiol compound (C5) A functional group formed by the reaction of an epoxy group derived from a silane coupling agent with at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having a (meth)acryloyl group and an amino group. (C6) Isocyanato group derived from isocyanate compounds (C7) Mercapto group derived from thiol compounds

[0051] The functional groups imparted to the surface of the core film 2 by the functional group imparting treatment preferably contain, among the functional groups (C1) to (C7) above, a functional group reactive with a functional group of the polymerizable composition that forms the organic layer 3 formed after the functional group imparting treatment. These functional groups may be of one type alone, or may contain two or more types. Examples of functional groups imparted to the surface of the core film 2 by the functional group imparting treatment include epoxy groups, amino groups, mercapto groups, isocyanato groups, carboxy groups, hydroxyl groups, and (meth)acryloyl groups.

[0052] Examples of the silane coupling agents having an epoxy group in (C1) and (C5) include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. Examples of the silane coupling agent having an amino group in (C1) and (C2) include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Examples of the silane coupling agents having a (meth)acryloyl group in (C1) and (C4) include 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane. Examples of the silane coupling agent having a mercapto group in (C1) and (C3) include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

[0053] The epoxy compounds in (C2) and (C3) are those other than silane coupling agents, and examples thereof include the above-mentioned bifunctional epoxy compounds.

[0054] The thiol compounds in (C2), (C4), (C5) and (C7) are, other than silane coupling agents, for example, the bifunctional thiol compounds mentioned above. The amino compounds in (C3) and (C5) are those other than silane coupling agents, and examples thereof include the above-mentioned bifunctional amino compounds. The isocyanate compounds in the functional groups (C3) and (C6) are not limited to silane coupling agents, and examples thereof include the bifunctional isocyanate compounds described above.

[0055] Examples of the compound (C3) having a (meth)acryloyl group and an epoxy group include glycidyl (meth)acrylate. Examples of the compounds (C3) and (C5) having a (meth)acryloyl group and an amino group include (meth)acrylamide.

[0056] The functional group imparting treatment can be carried out by applying a solution containing at least one selected from the group consisting of the following (c1) to (c7): (c1) a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group. (c2) a silane coupling agent having an amino group and at least one compound selected from the group consisting of an epoxy compound and a thiol compound (c3) a silane coupling agent having a mercapto group and at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group; (c4) A silane coupling agent having a (meth)acryloyl group and a thiol compound (c5) a silane coupling agent having an epoxy group and at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having an amino group and a (meth)acryloyl group; (c6) Isocyanate compounds (c7) Thiol compounds

[0057] The compounds (c1) to (c7) correspond to the functional groups (C1) to (C7) described above, respectively, and generate these functional groups. That is, by carrying out a functional group imparting treatment using a solution containing (c1), a functional group imparting treated surface 1a containing the functional group (C1) can be formed. The same applies to (c2) to (c7). For example, when a dithiol compound is reacted with an amino group in the treatment (c2), a mercapto group, which is a functional group possessed by the dithiol compound, is introduced to the terminal.Similarly, when a polyfunctional isocyanate compound is reacted with a mercapto group in the treatment (c3), an isocyanato group, which is a functional group possessed by the polyfunctional isocyanate compound, is introduced to the terminal.

[0058] It should be noted that the functional groups (C1) to (C7) react with the functional groups of the compounds constituting the organic layer 3, and therefore it is impossible to confirm their presence. Furthermore, the functional groups generated using the compounds (c1) to (c7) are not limited to a single type, and may be diverse. In light of these circumstances, in the present invention, based on the well-known technology that a predetermined functional group is generated by the reaction of a predetermined functional group with another predetermined functional group and the inference based thereon, it is assumed that a functional group-imparted surface 1a having the predetermined functional group is formed by performing a functional group imparting treatment using a compound having the predetermined functional group, and the expressions (C1) to (C7) and (c1) to (c7) are used.

[0059] The method for applying the solution in the functional group imparting treatment is not particularly limited, and for example, a dipping method, a spraying method, or the like can be used. In the case of the immersion method, for example, the core film is immersed in the solution having a concentration of about 0.5 to 50% by mass at 20 to 100°C for 1 minute to 5 days, and then removed and dried at room temperature to 100°C for 1 minute to 5 hours, thereby forming the functional group-imparting treated surface 1a. In the case of the spray method, for example, the solution having a concentration of about 0.5 to 50% by mass is sprayed onto the core film, and then dried at room temperature to 100°C for 1 minute to 5 hours, thereby forming the functional group-imparting treated surface 1a.

[0060] The functional group imparting treatment is preferably carried out after the above-described surface treatment, whereby the core film and the organic layer are more likely to be firmly bonded together due to the synergistic effect of the chemical bonding brought about by the surface treatment and the functional group imparting treatment.

[0061] [zygote] FIG. 2 shows one embodiment of the bonded structure of the present invention. The bonded structure 10 shown in FIG. 2 is formed by bonding a first substrate 4 and a second substrate 5 together by welding via the organic layers 3 on both sides of the heat-sealable film 1. The bonded structure thus obtained exhibits particularly excellent bonding strength. While the details of the mechanism are unclear, it is presumed that the main factor is the formation of some kind of chemical bond at the interface between the organic layers 3 on both sides of the heat-sealable film 1 and each substrate. However, with current technology, it is impossible or impractical to distinguish the heat-sealable film from those not produced by in situ polymerization by specifying their specific chemical structure or the state or properties of the interface. From the viewpoint of ease of handling as the heat-sealable film 1, the thickness of the heat-sealable film 1 is preferably 1 to 1000 μm for the core film 2 and 1 to 500 μm for the organic layer 3, more preferably 5 to 500 μm for the core film 2 and 5 to 200 μm for the organic layer 3, and even more preferably 5 to 250 μm for the core film 2 and 5 to 50 μm for the organic layer 3.

[0062] The first substrate 4 and the second substrate 5 are each made of one material selected from the group consisting of metal, resin, ceramic, and glass. Examples of metals include aluminum, iron, copper, magnesium, and steel, and examples of resins include thermoplastic resin, thermosetting resin, and fiber-reinforced plastic (FRP). The first substrate 4 and the second substrate 5 may be combined in any manner. The shapes of the first substrate 4 and the second substrate 5 are not particularly limited.

[0063] [Method of manufacturing the bonded body] Methods for welding the first substrate 4 and the second substrate 5 via the organic layers 3 on both sides of the heat-sealable film 1 include a method in which the heat-sealable film 1 is sandwiched between the substrates and welded by at least one method selected from the group consisting of ultrasonic welding, vibration welding, electromagnetic induction, high-frequency welding, laser welding, and heat pressing, and a method in which one organic layer of the heat-sealable film 1 and the first substrate 4 are welded in advance, and another thermoplastic resin material is molded on top of the other organic layer by injection molding. The organic layers on both sides of the core film may be the same or different, depending on the substrates to be bonded. [Example]

[0064] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples. In the following examples, the "first substrate 4" and the "second substrate 5" are collectively referred to as the bonding substrate.

[0065] <Core film> [Table 1]

[0066] <Joining base material> The following bonding substrates (width 1.0 cm, length 5 cm, thickness 2.0 mm) were prepared. PVC resin board: Takiron C.I. PVC board (transparent) PC plate: Takiron C.I. Polycarbonate Plate PC (transparent) PP Board: AS ONE Part Number 2-9221-02 Natural PP Board PE board: Hikari Polyplat PE340-1 (polyethylene, low-foam material, white) Stainless steel plate (SUS-304) Aluminum plate (A6063)

[0067] [Examples 1 to 13] <Core film surface treatment> (Core film surface treatment-1) UV ozone treatment UV ozone treatment was performed on both sides of each of the PPS, PET, PVC, and PVDC films shown in Table 1 using a tabletop surface treatment device PL16-110 manufactured by Sen Engineering Co., Ltd., irradiating both sides with ultraviolet light using a low-pressure ultraviolet lamp at an irradiation distance of 5 cm for an irradiation time of 2 minutes. (Core film surface treatment-2) Corona discharge treatment Corona discharge treatment was performed on both sides of each of the PC, PA6, and PI films shown in Table 1 using a KCT-4A manufactured by Kasuga Electric Co., Ltd., under conditions of an output of 104 W, a speed of 1 m / min, and an electrode distance of 2 mm, six times on each side. (Core film surface treatment-3) Plasma treatment + functional group addition treatment The aluminum foil and glass foil shown in Table 1 were treated to provide functional groups on both sides as follows. First, plasma treatment (atmospheric pressure plasma treatment machine FG5001 manufactured by Plasmatreat Inc., irradiation distance: 15 mm, feed rate: 5 m / min) was performed on both sides. Next, the stainless steel and aluminum foils after the surface treatment were immersed for 5 minutes in a 70°C silane coupling agent solution prepared by dissolving 0.5 g of 3-aminopropyltrimethoxysilane (KBM-903; silane coupling agent, manufactured by Shin-Etsu Silicone Co., Ltd.) in 100 g of industrial ethanol, and then removed to impart amino groups to the surfaces.

[0068] <Surface treatment of bonding substrate> The stainless steel plate (SUS-304) was degreased with acetone, and the aluminum plate (A6063) had amino groups attached to its surface using the same method as for the aluminum foil used as the core film (the method described in (Surface treatment of core film-3) above). No surface treatment was performed on the other substrates.

[0069] <Heat-welding film> (Polymerizable composition A) Polymerizable composition A was prepared by dissolving 100 g of phenol novolac epoxy resin “N-740” (manufactured by DIC Corporation), 41.6 g of bifunctional thiol compound: 1,4-bis(3-mercaptobutyryloxy)butane “Karenz MT BD1” (manufactured by Showa Denko K.K.), and 2.8 g of triphenylphosphine in 263 g of methyl ethyl ketone. (Thermal adhesive film AA) Polymerizable composition A was applied to both surfaces of the core film so that the thickness after solvent evaporation was as shown in Table 2. The solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 70°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film AA.

[0070] (Polymerizable composition B) Polymerizable composition B was prepared by mixing 100 g of polymerizable composition A with a solution prepared by dissolving 35 g of chlorinated polypropylene "Superchlorine 814HS" (manufactured by Nippon Paper Industries Co., Ltd.) in 65 g of methyl ethyl ketone. (Heat-welding film BB) Polymerizable composition B was applied to both surfaces of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 2. The solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 70°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film BB.

[0071] (Polymerizable composition C) 100 g of diphenylmethane diisocyanate, 60.8 g of propylene glycol, and 0.6 g of 2,4,6-tris(dimethylaminomethyl)phenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were dissolved in 299 g of methyl ethyl ketone to prepare a polymerizable composition C'. Next, 100 g of polymerizable composition C' was mixed with a solution prepared by dissolving 35 g of chlorinated polypropylene "Superchlorine 814HS" (manufactured by Nippon Paper Industries Co., Ltd.) in 65 g of methyl ethyl ketone to prepare polymerizable composition C'. (Thermal adhesive film CC) Polymerizable composition C was applied to both surfaces of the core film so that the thickness after solvent evaporation was the thickness shown in Table 2. The solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 100°C for 1 hour to carry out a polymerization reaction, thereby obtaining a heat-weldable film CC.

[0072] (Polymerizable composition D) Polymerizable composition D was prepared by dissolving 100 g of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bifunctional epoxy compound), 5.6 g of bisphenol A, 0.4 g of triphenylphosphine, and 196 g of methyl ethyl ketone (MEK). (Heat-welding film DD) Polymerizable composition D was applied to both surfaces of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 2, the solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 150°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film DD.

[0073] (Polymerizable composition E) Polymerizable composition E was prepared by dissolving 100 g of an epoxy resin having a fluorene skeleton, PG-100 (manufactured by Osaka Gas Chemicals Co., Ltd.), 84.3 g of a phenolic compound having a fluorene skeleton, BPEF (manufactured by Osaka Gas Chemicals Co., Ltd.), and 1.4 g of triphenylphosphine in 342 g of methyl ethyl ketone. (Heat-welding film EE) Polymerizable composition E was applied to both surfaces of the core film so that the thickness after solvent evaporation was the thickness shown in Table 2. The solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 190°C for 1 hour to carry out a polymerization reaction, thereby obtaining a heat-weldable film EE.

[0074] (Heat-welding film AB) Polymerizable composition A was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness listed in Table 2, the solvent was allowed to evaporate at room temperature for 30 minutes, and the film was left to stand on one surface of the core film at 70°C for 1 hour to carry out a polymerization reaction. Subsequently, polymerizable composition B was applied to the other surface of the core film so that the thickness after solvent evaporation would be the thickness listed in Table 2, the solvent was allowed to evaporate at room temperature for 30 minutes, and the film was left to stand on both surfaces of the core film at 70°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film AB.

[0075] (Thermal adhesive film AD) Polymerizable composition A was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness listed in Table 2. The solvent was allowed to evaporate at room temperature for 30 minutes, and the film was left to stand on one surface of the core film at 70°C for 1 hour to carry out a polymerization reaction. Subsequently, polymerizable composition D was applied to the other surface of the core film so that the thickness after solvent evaporation would be the thickness listed in Table 2. The solvent was allowed to evaporate at room temperature for 30 minutes, and the film was left to stand on both surfaces of the core film at 150°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film AD.

[0076] <Bonding of substrates and measurement of bond strength> (welding) The "bonding substrate / thermal adhesive film / bonding substrate" combinations shown in Table 2 were overlapped so that the bonding area was 1.0 cm x 0.5 cm. The overlapping state was clamped with a double clip and left to stand in a drying oven at 80°C for 10 minutes, and then returned to room temperature to obtain a bonded body.

[0077] (tensile shear strength) The resulting bonded body was left at room temperature for 5 minutes, and then subjected to a tensile shear strength test in accordance with JIS K 6850:1999 using a tensile testing machine (Universal Testing Machine Autograph "AG-IS" (Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm / min) at 23°C to measure the bond strength. The measurement results are shown in Table 2.

[0078] [Table 2]

[0079] [Comparative Examples 1 to 13] <Core film surface treatment> The core film was subjected to a surface treatment in the same manner as in Examples 1 to 13.

[0080] <Surface treatment of bonding substrate> The bonding substrate was subjected to surface treatment in the same manner as in Examples 1 to 13.

[0081] <Heat-welding film> (Thermal adhesive film A) Polymerizable composition A was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 3, the solvent was evaporated at room temperature for 30 minutes, and the film was left on one surface of the core film at 70°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film A.

[0082] (Thermal adhesive film B) Polymerizable composition B was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 3, the solvent was evaporated at room temperature for 30 minutes, and the film was left on one surface of the core film at 70°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film B.

[0083] (Thermal adhesive film C) Polymerizable composition C was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 3, the solvent was evaporated at room temperature for 30 minutes, and the film was left on one surface of the core film at 100°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film C.

[0084] (Thermal adhesive film D) Polymerizable composition D was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 3, the solvent was evaporated at room temperature for 30 minutes, and the film was left on one surface of the core film at 150°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film D.

[0085] (Thermal adhesive film E) Polymerizable composition E was applied to one surface of the core film so that the thickness after solvent evaporation would be the thickness shown in Table 3, the solvent was evaporated at room temperature for 30 minutes, and the film was left on one surface of the core film at 190°C for 1 hour to carry out a polymerization reaction, thereby obtaining heat-weldable film E.

[0086] <Bonding of substrates and measurement of bond strength> (welding) The "bonding substrate / thermal adhesive film / bonding substrate" combinations shown in Table 3 were overlapped so that the bonding area was 1.0 cm x 0.5 cm, and the overlapping state was clamped with double clips and left to stand in a drying oven at 80°C for 10 minutes, and then returned to room temperature to attempt bonding. In Comparative Examples 1 to 4 and 8 to 13, bonding was not possible.

[0087] (tensile shear strength) For those that could be bonded (Comparative Examples 5 to 7), the resulting bonded bodies were left at room temperature for 5 minutes, and then subjected to a tensile shear strength test in an atmosphere of 23°C in accordance with JIS K 6850:1999 using a tensile tester (Universal Testing Machine Autograph "AG-IS" (Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm / min) to measure the bond strength. The measurement results are shown in Table 3.

[0088] [Table 3]

[0089] [Examples 14 to 15] <Core film surface treatment> Corona discharge treatment was performed on both sides of the PI shown in Table 1. The corona discharge treatment was performed six times on each side using a KCT-4A corona discharger manufactured by Kasuga Electric Co., Ltd., under conditions of an output of 104 W, a speed of 1 m / min, and an electrode distance of 2 mm.

[0090] <Surface treatment of bonding substrate> Amino groups were imparted to the surface of the aluminum plate (A6063) using the same method as that used for the aluminum foil serving as the core film (the method described in (Surface Treatment-3) above).

[0091] <Heat-welding film> (Polymerizable composition F) Polymerizable composition F was prepared by dissolving 46.9 g of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bifunctional epoxy compound), 30.8 g of epoxy resin PG-100 having a fluorene skeleton (manufactured by Osaka Gas Chemicals Co., Ltd.), 2.89 g of bisphenol S, 19.0 g of phenol compound TAM-005 having a nitrogen atom (manufactured by Aica Kogyo Co., Ltd.), and 0.4 g of triphenylphosphine in 186 g of methyl ethyl ketone. (Heat-welding film FF) Polymerizable composition F was applied to both surfaces of the core film (PI) so that the thickness after solvent evaporation was 0 μm. The solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 150°C for 1 hour to carry out a polymerization reaction, thereby obtaining a heat-weldable film FF.

[0092] (Polymerizable composition G) Polymerizable composition G was prepared by dissolving 100 g of jER (registered trademark) 1001 (manufactured by Mitsubishi Chemical Corporation, bifunctional epoxy compound), 24.6 g of meta-para-cresol novolak LF-100 (manufactured by Lignite Corporation), and 0.5 g of triphenylphosphine in 231 g of methyl ethyl ketone. (Thermal adhesive film GG) Polymerizable composition G was applied to both surfaces of the core film (PI) so that the thickness after solvent evaporation was 0 μm. The solvent was evaporated at room temperature for 30 minutes, and the mixture was left on both surfaces of the core film at 150°C for 1 hour to carry out a polymerization reaction, thereby obtaining a heat-weldable film FF.

[0093] <Bonding of substrates and measurement of bond strength> (welding) The "bonding substrate / heat-welding film / bonding substrate" was overlapped so that the bonding area was 1.0 cm x 0.5 cm, and the overlapping state was clamped with a double clip and left to stand in a drying oven at 190°C for 10 minutes, and then returned to room temperature to obtain a bonded body.

[0094] (tensile shear strength) The resulting bonded body was left at room temperature for 5 minutes, and then subjected to a tensile shear strength test in accordance with JIS K 6850:1999 using a tensile tester (Universal Testing Machine Autograph "AG-IS" (Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm / min) at 23°C to measure the bond strength. The measurement results are shown in Table 4.

[0095] [Comparative Example 14] <Surface treatment of bonding substrate> In the same manner as in Example 14, amino groups were added to the surface of an aluminum plate (A6063).

[0096] <Bonding of substrates and measurement of bond strength> (welding) Polymerizable composition F was applied to the substrate to a thickness of 15 μm after evaporation of the solvent, and the solvent was evaporated at room temperature for 30 minutes. The coating was then left at 150°C for 1 hour to allow the polymerization reaction to occur, yielding aluminum with a thermally welded layer F. Next, the aluminum pieces with the thermal welding layer F were overlapped with each other via the thermal welding layer F so that the joint was 1.0 cm x 0.5 cm, and while overlapping, they were clamped with double clips and left to stand in a drying oven at 190°C for 10 minutes, after which they were returned to room temperature to obtain a joint.

[0097] (tensile shear strength) The bonding strength was measured in the same manner as in Example 14. The measurement results are shown in Table 4.

[0098] [Comparative Example 15] <Surface treatment of bonding substrate> In the same manner as in Example 15, amino groups were added to the surface of an aluminum plate (A6063).

[0099] <Bonding of substrates and measurement of bond strength> (welding) Polymerizable composition G was applied to the substrate to a thickness of 15 μm after evaporation of the solvent, and the solvent was evaporated at room temperature for 30 minutes. The coating was then left at 150°C for 1 hour to allow the polymerization reaction to occur, yielding aluminum with a thermally welded layer G. Next, the aluminum pieces with thermal welding layer F were overlapped with each other via thermal welding layer G so that the joint was 1.0 cm x 0.5 cm, and while overlapping, they were clamped with double clips and left to stand in a drying oven at 190°C for 10 minutes, after which they were returned to room temperature to obtain a joint.

[0100] (tensile shear strength) The bonding strength was measured in the same manner as in Example 15. The measurement results are shown in Table 4.

[0101] [Table 4]

[0102] Example 16 (Thermal adhesive film with an organic layer not polymerized in situ) A solution of 35 g of phenoxy resin YP-50S (manufactured by Nippon Steel Chemical & Material Co., Ltd.) dissolved in 65 g of MEK was applied to both sides of the PET (core film) shown in Table 1 so that the thickness after drying was 20 μm, and the film was left to dry at 70°C for 1 hour to obtain a heat-weldable film. (welding) This heat-welding film was sandwiched between two SUS-304 plates, overlapping them so that the joint was 1.0 cm x 0.5 cm. The overlapping plates were clamped with double clips and left to stand in a drying oven at 80°C for 10 minutes, then cooled to room temperature to obtain a joint. (tensile shear strength) The resulting bonded body was left at room temperature for 5 minutes, and then subjected to a tensile shear strength test in accordance with JIS K 6850:1999 using a tensile tester (Universal Testing Machine Autograph "AG-IS" (Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm / min) at 23°C to measure the bond strength. The measurement results are shown in Table 5.

[0103] Example 17 (Thermal adhesive film with an organic layer not polymerized in situ) A solution of 35 g of phenoxy resin YP-50S (manufactured by Nippon Steel Chemical & Material Co., Ltd.) dissolved in 65 g of MEK was applied to both sides of the aluminum (core film) shown in Table 1 so that the thickness after drying was 20 μm, and the film was left to dry at 70°C for 1 hour to obtain a heat-weldable film. (welding) This heat-welding film was sandwiched between two SUS-304 plates, overlapping them so that the joint was 1.0 cm x 0.5 cm. The overlapping plates were clamped with double clips and left to stand in a drying oven at 80°C for 10 minutes, then cooled to room temperature to obtain a joint. (tensile shear strength) The resulting bonded body was left at room temperature for 5 minutes, and then subjected to a tensile shear strength test in accordance with JIS K 6850:1999 using a tensile tester (Universal Testing Machine Autograph "AG-IS" (Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm / min) at 23°C to measure the bond strength. The measurement results are shown in Table 5.

[0104] [Table 5] [Industrial Applicability]

[0105] A joined body obtained by joining together the same or different types of substrates via the heat-sealable film according to the present invention can be used, for example, as automotive parts such as door side panels, bonnet roofs, tailgates, steering hangers, A-pillars, B-pillars, C-pillars, D-pillars, crash boxes, power control unit (PCU) housings, electric compressor components (inner wall portions, intake port portions, exhaust control valve (ECV) insertion portions, mount boss portions, etc.), lithium ion battery (LIB) spacers, battery cases, and LED headlamps, as well as structures for smartphones, laptops, tablet computers, smartwatches, large liquid crystal televisions (LCD-TVs), and outdoor LED lighting, but is not limited to these exemplary uses. [Explanation of symbols]

[0106] 1. Heat-sealable film 2 Core film 3 Organic layer 4. First substrate 5 Second substrate 10 zygote

Claims

1. A heat-sealable film having a layer structure of three or more layers including a core film and organic layers forming two outermost layers, The organic layer is a polymer layer formed by polymerizing a polymerizable composition containing at least one of the following (1) to (6) and (8) to (13) on the surface-treated surface of the core film: The heat-weldable film, wherein the surface treatment is at least one selected from the group consisting of plasma treatment, corona discharge treatment, UV ozone treatment, blast treatment, polishing treatment, etching treatment and chemical conversion treatment. (1) Combination of a bifunctional isocyanate compound and a diol (2) Combination of a bifunctional isocyanate compound and a bifunctional amino compound (3) Combination of a bifunctional isocyanate compound and a bifunctional thiol compound (4) Combination of a bifunctional epoxy compound and a diol (5) Combination of a difunctional epoxy compound and a difunctional carboxy compound (6) Combination of a bifunctional epoxy compound and a bifunctional thiol compound (8) A combination of a bifunctional epoxy compound and at least one of a phenol novolac resin and a cresol novolac resin. (9) A combination of at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin with a bifunctional phenol compound. (10) A combination of a bifunctional thiol compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin. (11) A combination of a bifunctional amino compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin. (12) A combination of a bifunctional carboxy compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin. (13) A combination of a bifunctional isocyanate compound and at least one of a phenol novolac resin and a cresol novolac resin.

2. 2. The heat-weldable film according to claim 1, wherein the core film is a resin film made of at least one resin selected from the group consisting of polyvinyl chloride, polyphenylene sulfide, polyethylene terephthalate, nylon, polyvinylidene chloride, and polyimide.

3. The heat-weldable film according to claim 1 , wherein the core film is an inorganic foil made of at least one material selected from the group consisting of aluminum, copper, and glass.

4. A method for producing a heat-sealable film having a layer structure of three or more layers, the film having a core film and heat-sealable organic layers laminated on both sides of the core film, comprising: On the surface-treated surface of the core film, a polymerizable composition containing at least one of the following (1) to (6) and (8) to (13) is polymerized to form the organic layer: The method for producing a heat-weldable film, wherein the surface treatment is at least one selected from the group consisting of plasma treatment, corona discharge treatment, UV ozone treatment, blast treatment, polishing treatment, etching treatment and chemical conversion treatment. (1) Combination of a bifunctional isocyanate compound and a diol (2) Combination of a bifunctional isocyanate compound and a bifunctional amino compound (3) Combination of a bifunctional isocyanate compound and a bifunctional thiol compound (4) Combination of a bifunctional epoxy compound and a diol (5) Combination of a difunctional epoxy compound and a difunctional carboxy compound (6) Combination of a bifunctional epoxy compound and a bifunctional thiol compound (8) A combination of a bifunctional epoxy compound and at least one of a phenol novolac resin and a cresol novolac resin. (9) A combination of at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin with a bifunctional phenol compound. (10) A combination of a bifunctional thiol compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin. (11) A combination of a bifunctional amino compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin. (12) A combination of a bifunctional carboxy compound and at least one of a phenol novolac epoxy resin and a cresol novolac epoxy resin. (13) A combination of a bifunctional isocyanate compound and at least one of a phenol novolac resin and a cresol novolac resin.

5. 5. The method for producing a heat-weldable film according to claim 4, wherein before forming the organic layer, the core film is treated with a solution containing at least one selected from the group consisting of the following (c1) to (c7), thereby providing functional groups on the surface of the core film. (c1) A silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group. (c2) a silane coupling agent having an amino group and at least one compound selected from the group consisting of an epoxy compound and a thiol compound; (c3) a silane coupling agent having a mercapto group and at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group; (c4) A silane coupling agent having a (meth)acryloyl group and a thiol compound (c5) a silane coupling agent having an epoxy group and at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having a (meth)acryloyl group and an amino group; (c6) Isocyanate compound (c7) thiol compounds

6. A bonded body obtained by joining a first substrate made of one material selected from the group consisting of metals, resins, ceramics, and glass and a second substrate made of one material selected from the group consisting of metals, resins, ceramics, and glass by welding via the heat-weldable film according to any one of claims 1 to 3.

7. A method for producing a bonded body, comprising welding a first substrate made of one material selected from the group consisting of metal, resin, ceramic, and glass to a second substrate made of one material selected from the group consisting of metal, resin, ceramic, and glass via the heat-welding film according to any one of claims 1 to 3, thereby integrally bonding the first substrate and the second substrate.

8. 8. The method for producing a joined body according to claim 7, wherein the welding is carried out by at least one method selected from the group consisting of ultrasonic welding, vibration welding, electromagnetic induction welding, high frequency welding, laser welding, and heat pressing.

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