JP2020100043A - Hot-melt adhesive sheet for electromagnetic induction heating, bonded structure using the same, method for manufacturing bonded structure, and peeling method - Google Patents

Abstract

To provide a hot melt adhesive sheet for electromagnetic induction heating, in which a heating position may be easily identified upon electromagnetic induction heating and which can be firmly adhered to an adherend, and to provide a bonded structure in which a laminate formed by using the adhesive sheet and the adherend are firmly adhered to each other, a method for producing a bonded structure adhered by electromagnetic induction heating, and a method for easily peeling the laminate and the adherend from each other by electromagnetic induction heating.SOLUTION: There is provided a hot melt adhesive sheet 10 for electromagnetic induction heating, which is formed by laminating a thermoplastic hot melt adhesive layer (C), a metal layer (A), and a thermosensitive coloring layer (D) in this order. The bonded structure is also provided in which a surface of the thermoplastic hot melt adhesive layer (C) of the hot melt adhesive sheet is adhered to an adherend.SELECTED DRAWING: Figure 1

Description

The present invention provides a hot melt adhesive sheet for electromagnetic induction heating, which is formed by laminating a thermoplastic hot melt adhesive layer, a metal layer, and a thermosensitive coloring layer in this order, and an adhesive structure in which the adhesive sheet and an adherend are adhered to each other. The present invention relates to an object, a method for manufacturing an adhesive structure that adheres by electromagnetic induction heating, and a method for peeling off by electromagnetic induction heating.

Since the high-growth era, concrete has been used in many industries such as construction and civil engineering. Nails and bolts have been used to bond concrete to other members. In these methods, the work is relatively easy, but since the points are bonded, the force is concentrated at one point, and it is desirable to bond the surfaces in order to disperse the force. In addition, there is a problem that the appearance is impaired because a protrusion or a buildup appears at the joint. In order to solve these problems, an epoxy adhesive is used for bonding with concrete (Patent Documents 1 and 2). However, since the epoxy adhesive takes time to cure, it must be fixed for a long time after bonding the other base material to concrete, or it will peel off if not fixed. Had problems such as. Further, when a reinforcing sheet for preventing deterioration or peeling of concrete is provided on the surface of concrete, nails, bolts, or adhesives are similarly used.

An adhesive tape has been developed as a method that does not require time to cure the adhesive (Patent Document 3). Adhesive tape has the advantage of being able to shorten the curing time, but its adhesive strength is weak, and it is difficult to put it to practical use because the adhesive strength decreases when water or heat is applied.
On the other hand, in recent years, an adhesive melting device using an electromagnetic induction heating method, an electromagnetic induction heating adhesive sheet, and the like have been developed (Patent Document 4). Electromagnetic induction heating is a method of generating an eddy current in a metal of a conductive material in a magnetic field by applying an alternating current of high frequency to a coil of an electromagnetic induction heating device to generate an eddy current. This is a heating method in which the conductive material is heated by heat. The higher the frequency of the alternating current flowing in the coil, the faster the change in the magnetic field, the larger the eddy current resulting therefrom, and the shorter the heating time. The bonding method using electromagnetic induction heating has a short curing time, and can suppress a decrease in bonding strength due to water and heat.
However, since the bonding by electromagnetic induction heating is a partial bonding method in which only the coil part is heated as described above, in order to bond a large area evenly, first ground the electromagnetic induction heating device at the first bonding point. It is necessary to repeat the operations of heating and adhering, then moving the electromagnetic induction heating device to the second adhering position, and heating and adhering again. At that time, the heated portion and the unheated portion cannot be visually discriminated from each other.Therefore, the moving distance of the electromagnetic induction heating device largely depends on the operator's discretion. There is a problem in that it is heated to cause charring, and when the moving distance is long, there are portions that are not bonded.

JP 2001-172597 A Japanese Patent Publication No. 6-13689 Japanese Unexamined Patent Publication No. 8-319462 JP 2001-262085 A

An object of the present invention is to provide a structure of an adhesive sheet by laminating a thermoplastic hot melt adhesive layer (C), a metal layer (A), and a pressure-sensitive color forming layer (D) in this order, so that the electromagnetic induction heating There is provided a hot melt adhesive sheet for electromagnetic induction heating, in which the heating position can be easily identified and the adherend and the adhesive sheet can be firmly adhered. In addition, a laminated structure (Y) formed by using the adhesive sheet and an adherend (X) are firmly adhered to each other, a method for manufacturing an adhesive structure in which they are adhered by electromagnetic induction heating, and An object of the present invention is to provide a method capable of easily peeling by electromagnetic induction heating.

That is, the present invention relates to a hot melt adhesive sheet for electromagnetic induction heating, in which a thermoplastic hot melt adhesive layer (C), a metal layer (A), and a thermosensitive coloring layer (D) are laminated in this order, and the present invention. This is solved by an adhesive structure in which the thermoplastic hot melt adhesive layer (C) surface of the electromagnetic induction heating hot melt adhesive sheet and the adherend layer (E) are adhered.

Further, the present invention relates to the hot melt adhesive sheet for electromagnetic induction heating, which has a thermosetting adhesive layer (B) between the metal layer (A) and the thermoplastic hot melt adhesive layer (C). ..

Further, the thermoplastic hot melt adhesive layer (C) relates to the hot melt adhesive sheet for electromagnetic induction heating including a mesh.

The thermosensitive coloring layer (D) also relates to the hot-melt adhesive sheet for electromagnetic induction heating, which contains a leuco dye and a developer.

The present invention also relates to an adhesive structure having a laminate (Y) formed by using the electromagnetic induction heating hot melt adhesive sheet and an adherend (X).

The adherend (X) relates to the adhesive structure having a primer layer on the surface of the adherend.

Further, the hot melt adhesive sheet for electromagnetic induction heating is heated by an electromagnetic induction heating device to bond the hot melt adhesive sheet for electromagnetic induction heating and the adherend (X) to each other. It relates to a manufacturing method.

Further, the adhesive structure is heated by an electromagnetic induction heating device to soften or melt the thermoplastic hot melt adhesive layer (C) in a solid state, and to form an adherend (X) and a laminate (Y). The present invention relates to a method for peeling.

According to the present invention, it is possible to provide an adhesive structure in which the heating position can be easily identified and the adherend (X) and the hot-melt adhesive sheet for electromagnetic induction heating are firmly adhered. Further, by using the electromagnetic induction heating device, it is possible to provide a manufacturing method capable of manufacturing these bonded structures in a short time without aging, and a method of peeling the adherend without damaging the adherend.

The typical sectional view showing an example of the hot-melt adhesive sheet for electromagnetic induction heating of the present invention. The typical sectional view showing an example of the adhesion structure of the present invention. The typical sectional view showing an example of the adhesion structure of the present invention. The typical sectional view showing an example of the adhesion structure of the present invention. The typical sectional view showing an example of the adhesion structure of the present invention.

Hereinafter, the present invention will be described in detail.

≪Hot melt adhesive sheet for electromagnetic induction heating≫
The hot-melt adhesive sheet for electromagnetic induction heating of the present invention comprises a thermoplastic hot-melt adhesive layer (C), a metal layer (A), and a thermosensitive coloring layer (D), which are laminated in this order. Adhesive structure having an adherend (X) and a laminate (Y) of a thermoplastic hot melt adhesive layer (C), a metal layer (A), and a thermosensitive coloring layer (D) by being adhered to It is used to manufacture things.
Preferably, the thermosetting adhesive layer (B) is provided between the metal layer (A) and the thermoplastic hot melt adhesive layer (C). By having the heat-cured adhesive layer (B), an adhesive sheet can be produced without wrinkles in the metal layer (A), and olefins that cannot be directly adhered to the metal layer (A), etc. Is preferable because it can be used as the thermoplastic hot melt adhesive layer (C).
Further, the thermoplastic hot melt adhesive layer (C) may include a mesh. By including the mesh in the thermoplastic hot melt adhesive layer, the strength of the adhesive sheet is increased, and peeling of the adhesive sheet can be prevented.

For example, referring to FIG. 1, the hot-melt adhesive sheet 10 for electromagnetic induction heating includes a metal layer (A), a thermoplastic hot-melt adhesive layer (C), and a thermosensitive coloring layer (D) in this order. Have in. The hot melt adhesive sheet for electromagnetic induction heating may further have other layers.

<Thermoplastic hot melt adhesive layer (C)>
The thermoplastic hot melt adhesive layer (C) of the present invention preferably has a melt viscosity at 190° C. of 10 Pa·s or more and 1000 Pa·s or less, more preferably 20 Pa·s or more and 800 Pa·s or less. When the melt viscosity at 190° C. is 1000 Pa·s or more, the adhesive does not soak into the irregularities on the surface of the adherend, and a strong adhesive force cannot be obtained. Further, when the melt viscosity at 190° C. is 10 Pa·s or less, the cohesive force inherent to the adhesive is low and a strong adhesive force cannot be obtained. Examples of the thermoplastic hot melt adhesive layer of the present invention include ABS, polyamide, polyester, polyurethane, acrylic, polycarbonate, polystyrene, polyethylene, polypropylene, poly-1-butene, polyisobutylene, polymethylpentene, and propylene-ethylene copolymer. , Ethylene-propylene-diene copolymer, ethylene/butene-1 copolymer, ethylene/octene copolymer and other polyolefins, cyclopentadiene and ethylene and/or propylene copolymer and other cyclic polyolefins, ethylene/acetic acid Polyolefins having polar groups such as vinyl copolymer (EVA), ethylene/ethyl acrylate copolymer (EEA), isobutylene/maleic anhydride copolymer, maleic anhydride modified polypropylene, maleic acid modified polypropylene, acrylic Examples thereof include acid-modified polypropylene, styrene elastomer, and acid-modified polypropylene such as rubber. From the viewpoint of adhesive strength and durability, polyethylene, maleic acid-modified polypropylene and polyamide are preferable, and polyamide is more preferable.

A tackifier or the like may be added to the thermoplastic hot melt adhesive of the present invention in order to improve the adhesiveness. The main tackifier is not particularly limited, but is a petroleum resin such as phenol resin, modified phenol resin, terpene phenol resin, xylene phenol resin, cyclopentadiene-phenol resin, xylene resin, aliphatic type, alicyclic type and aromatic type. Resin, hydrogenated aliphatic type, alicyclic type, aromatic type petroleum resin, phenol-modified petroleum resin, rosin ester resin, hydrogenated rosin ester resin, low molecular weight polystyrene type resin, terpene resin, It is preferable to include a tackifying resin such as a hydrogenated terpene resin. The tackifier resins may be used alone or in combination of two or more.

A wax or the like may be added to the thermoplastic hot melt adhesive of the present invention for the purpose of reducing the viscosity. Main waxes include, but are not limited to, carnauba wax, candelilla wax, montan wax, paraffin wax, microwax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, oxides of these waxes, ethylene-acrylic acid copolymers. , Ethylene-methacrylic acid copolymer and the like. The wax can be used alone or in combination of two or more kinds.

The thermoplastic hot-melt adhesive layer of the present invention is preferably subjected to corona treatment on the surface, and particularly low polarity polyethylene, polypropylene, etc. are prepared by applying a thermosetting adhesive to the corona-treated surface and thermally curing it. , Adhere more firmly. The corona treatment may be carried out immediately before the thermosetting adhesive is applied or the corona treatment may be carried out in advance.

The thermoplastic hot melt adhesive layer of the present invention can be suitably used in the form of a film. The thickness of the thermoplastic hot melt adhesive layer of the present invention is preferably 10 μm or more and 500 μm or less. More preferably, it is 20 μm or more and 300 μm or less. If the thickness of the thermoplastic hot melt adhesive layer is less than 10 μm or more than 500 μm, poor adhesion may occur.

If necessary, various additives can be used as additives for the thermoplastic hot melt adhesive layer. Examples thereof include colorants, antiblocking agents, inorganic fillers, antioxidants, fillers, flame retardants, plasticizers, antistatic agents, light stabilizers, ultraviolet absorbers and heavy metal deactivators.

As the colorant, conventionally known colorants such as red, blue, green and yellow can be used, and any of pigments, dyes and pigments may be used, for example, monoazo type, diazo type, azo lake type, benzimidazolone. System, perylene system, diketopyrrolopyrrole system, condensed azo system, anthraquinone system, quinacridone system, phthalocyanine system, anthraquinone system, pigment system is pigment, perylene system, monoazo system, condensed azo system, isoindolinone system, oxidation system. Examples include titanium and carbon.

Examples of the antiblocking agent include silicone, unsaturated fatty acid amides such as erucic acid amide and oleic acid amide, and saturated fatty acid amides such as stearic acid amide and behenic acid amide.

Examples of the inorganic filler include particles such as metal, metal oxide and metal hydroxide, and fibrous particles. Specifically, glass fiber, carbon fiber, calcium silicate, calcium titanate, aluminum borate fiber, glass flakes, talc, kaolin, mica, hydrotalcite, calcium carbonate, zinc carbonate, zinc oxide, monohydrogen phosphate. Calcium, wollastonite, silica, zeolite, alumina, boehmite, aluminum hydroxide, titanium oxide, silicon oxide, magnesium oxide, calcium silicate, alumina sodium silicate, magnesium silicate, carbon nano-tube, graphite, copper, silver, aluminum, nickel , Iron, calcium fluoride, mica, montmorillonite, apatite and the like.

As antioxidants, high molecular weight hindered polyhydric phenols, triazine derivatives, high molecular weight hindered phenols, dialkyl phenol sulfides, 2,2-methylene-bis-(4-methyl-6-tert-butylphenol), 4 ,4-methylene-bis-(2,6-di-tert-butylphenol), 2,6-di-tert-butylphenol-p-cresol, 2,5-di-tert-butylhydroquinone, 2,2 ,4-trimethyl-1,2-dihydroquinone, 2,2,4-trimethyl-1,2-dihydroquinone, nickel dibutyl dithiocarbamate, 1-oxy-3-methyl-4-isopropylbenzene, 4,4- Butylidene bis-(3-methyl-6-tert-butylphenol), 2-mercaptobenzimidazole and the like can be mentioned.

Examples of the filler include wet silica, aluminum hydroxide, aluminum oxide, magnesium oxide, montmorillonite, mica, smectite, organized montmorillonite, organized mica, organized smectite and the like.

Examples of the flame retardant include phosphorus-containing compound flame retardants, halogen-containing compound flame retardants, sulfonic acid metal salt flame retardants, silicon-containing compound flame retardants, and the like.

Examples of the plasticizer include phthalic acid ester-based plasticizers, polyester-based plasticizers, aliphatic dibasic acid ester-based plasticizers, aliphatic monobasic acid ester-based plasticizers, phosphoric acid ester-based plasticizers, and citric acid ester-based plasticizers. , Epoxy-based plasticizers, trimellitic acid ester-based plasticizers, tetrahydrophthalic acid ester-based plasticizers, glycol-based plasticizers, and bisphenol A alkylene oxide derivatives.

The antistatic agent may be one that is widely used as an antistatic agent for plastics, and specifically, a nonionic surfactant (for example, fatty acid ester of polyhydric alcohol, ethylene oxide adduct of alkylamine, and alkyl). Fatty acid ester of ethylene oxide adduct of amine), anionic surfactant (eg, alkylbenzene sulfonate, higher alcohol sulfate salt, etc.), cationic surfactant (eg, aliphatic amine salt, quaternary ammonium salt) Etc.), and amphoteric surfactants (eg, imidazoline type, betaine type, etc.).

Examples of the light stabilizer include hindered amine compounds and benzoate compounds.

Examples of the UV absorber include benzophenone-based UV absorbers, triazine-based UV absorbers, and benzotriazole-based UV absorbers.

Examples of the heavy metal deactivator include salicylic acid derivatives, hydrazide derivatives, oxalic acid amide derivatives, and the like.

The above additives may be used alone or in combination of two or more at an arbitrary ratio as necessary.

[mesh]
In the adhesive sheet of the present invention, the thermoplastic hot melt adhesive layer (C) may include a mesh. By including the mesh in the thermoplastic hot melt adhesive layer, the strength of the adhesive sheet is increased, and peeling of the adhesive sheet can be prevented. The mesh substrate is more preferably composed of one or more fibers selected from the group consisting of polyester fibers, polyamide fibers, vinylon fibers, carbon fibers, glass fibers or polyolefin fibers. Among these, polyester fibers, polyamide fibers, vinylon fibers, and polyolefin fibers are particularly preferable because they are light and have excellent strength. In addition, the mesh may be, for example, a mesh capable of preventing a concrete deterioration factor from entering, or a mesh capable of reinforcing concrete having a reduced strength. When the adhesive sheet is heated by an electromagnetic induction heating device, heat may damage the mesh, so a mesh having high heat resistance is particularly preferable.

The method for obtaining the thermoplastic hot melt adhesive layer containing a mesh is not particularly limited, but for example, a film-shaped thermoplastic hot melt adhesive, a mesh, and a film-shaped thermoplastic hot melt adhesive are laminated in this order. The laminate can be obtained by heat laminating and melt-integrating the thermoplastic hot melt adhesives on both sides of the mesh.

<Heat-cured adhesive layer (B)>
The adhesive sheet of the present invention has a thermosetting adhesive layer formed of a thermosetting adhesive between the metal layer (A) and the thermoplastic hot melt adhesive layer (C). Good. By having a thermosetting adhesive layer, an adhesive sheet can be produced without wrinkles in the metal layer (A), and olefins that could not be directly adhered to the metal layer (A) are thermoplastic. It is preferable because it can be used as the hot melt adhesive layer (C). The thermosetting adhesive layer of the present invention is formed, for example, by a thermosetting adhesive having a base resin containing a base agent having a functional group such as polyester resin, polyurethane resin, acrylic resin, and epoxy resin, and a curing agent. Preferably.

[Main agent]
As the polyester resin, as the acid component of the monomer composition, for example, an aromatic dibasic acid such as dimethyl terephthalic acid, terephthalic acid, isophthalic acid, and phthalic acid, succinic acid, glutaric acid, adipic acid, β-methyladipic acid, Aliphatic dibasic acids such as pimelic acid, 1,6-hexanedicarboxylic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid and hexadecanedicarboxylic acid, and ethylene glycol, 1,2 as glycol components. -Propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentadiol, 1,5-pentadiol, 3-methylpentadiol, 1,3-hexane Glycols such as diols, 1,6-hexanediol, 1,4-cyclohexanediol, hydrogenated bisphenol A, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, etc. or their residue-forming derivatives. Alternatively, it can be obtained by appropriately selecting and copolymerizing a saturated bifunctional monomer composed of an α,ω-oxy acid such as caprolactone or a residue-forming derivative thereof by a conventional method.

The polyurethane resin can be obtained by reacting a polyol such as a polyether polyol, a polyester polyol, or a polymer polyol with an isocyanate compound consisting of polyisocyanate in the excess of the polyol. Examples of the ether polyol include bisphenol A, A low molecular weight compound having two or more active hydrogens, such as ethylene glycol, propylene glycol, butylene glycol, diols such as 1,6-hexanediol, triols such as glycerin and trimethylolpropane, and amines such as ethylenediamine and butylenediamine. Polymers obtained by ring-opening polymerization of one or more alkylene oxides such as propylene oxide, ethylene oxide, and tetrahydrofuran in the presence of one or more active hydrogen compounds are mentioned.

Examples of the polyester-based polyol include polybasic acids such as adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid and succinic acid, and bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4 A polymer obtained by dehydration condensation with a polyhydric alcohol such as butanediol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, or a lactone such as ε-caprolactone or α-methyl-ε-caprolactone And a condensation product of a hydroxycarboxylic acid such as castor oil, a reaction product of castor oil and ethylene glycol, and the above polyhydric alcohol.

Examples of the polymer polyol include graft-polymerized ethylenically unsaturated compounds such as acrylonitrile, styrene, and methyl (meth)acrylate with the polyether-based polyol or polyester-based polyol, and 1,2- or 1,4- Examples thereof include polybutadiene polyol and hydrogenated products thereof.

As the polyisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, diisocyanates such as dicyclohexylmethane diisocyanate, trimer of the above diisocyanates, triisocyanates such as triphenylmethane triisocyanate, In addition, crude MDI, which is a mixture of diphenylmethane diisocyanate, triphenylmethane triisocyanate, and the like, can be used. These polyisocyanates may be used alone or in combination of two or more.
The hydroxyl group-terminated polyurethane polymer is mixed with 1 hydroxyl group so that the isocyanate group is 2 to 8 and used as the adhesive.

Any epoxy resin may be used as long as it has two or more epoxy groups in one molecule, and specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin. , Alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate epoxy resin, acrylic acid modified epoxy resin (epoxy acrylate), phosphorus-containing epoxy resin and these halogen resins (bromination Epoxy resin, etc.) and hydrogenated substances. These epoxy resins may be used alone or in combination of two or more. Brominated epoxy resins and the like are particularly effective when flame retardancy is required for the adhesive. Since the acrylic acid-modified epoxy (epoxy acrylate) has photosensitivity, it is effective in imparting photocurability to the epoxy resin composition.

[Curing agent]
The curing agent can be used without particular limitation as long as it can be used for curing the main agent, but, for example, an isocyanate curing agent, an aliphatic amine curing agent, an alicyclic amine curing agent, Examples thereof include aromatic amine type curing agents, acid anhydride curing agents, dicyandiamide, boron trifluoride amine complex salts, and imidazole compounds. These may be used alone or in combination of two or more. The compounding amount of the curing agent can be determined according to the main agent.

Examples of additives for the thermosetting adhesive layer include silane coupling agents and antioxidants.

As the silane coupling agent, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy) ) Silane, vinyltriacetylsilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptoethyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloro Examples thereof include propyltriethoxysilane and vinyltrichlorosilane.

As the antioxidant, the antioxidant used in the thermoplastic hot melt adhesive layer described above is used.

The thermosetting adhesive of the present invention may contain various solvents. For example, acetone-based compounds such as methyl ethyl ketone (MEK) and methyl isobutyl ketone, cyclic ether-based compounds such as tetrahydrofuran (THF) and dioxolane, ester-based compounds such as ethyl acetate and butyl acetate, aromatic compounds such as toluene and xylene. Examples thereof include compounds, carbitol, cellosolve, methanol, isopropanol, butanol, and alcohol compounds such as propylenechol monomethyl ether. These may be used alone or in combination of two or more.

As a method for forming the thermosetting adhesive layer, a thermosetting adhesive may be applied to the film-shaped metal layer (A) or the film-shaped thermoplastic hot melt adhesive layer, followed by drying and thermosetting. preferable. Further, from the viewpoint of preventing wrinkles from being generated in the metal layer (A), it is preferable that the thermosetting adhesive is applied to a thermoplastic hot melt adhesive film to be formed.
As a device for applying the thermosetting adhesive, a comma coater, a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater, a reverse roll coater, a blade coater, a gravure coater, a microgravure coater, etc. Can be mentioned. The coating amount of the thermosetting adhesive is preferably about 1 to 50 μm in dry film thickness, more preferably 2 to 25 μm, and further preferably 2 to 10 μm.

As the heat-cured adhesive layer, it is preferable to use polyester resin and urethane resin as the main component from the viewpoints of adhesion to the metal layer (A) and the thermoplastic hot-melt adhesive layer, heat resistance, and water resistance. Polyester resins are preferred. It is more preferable to use an aromatic polyisocyanate curing agent as the curing agent.

<Metal layer (A)>
The metal layer of the present invention is for inducing an eddy current by a high frequency magnetic flux by an electromagnetic induction heating device, and melting the thermoplastic hot melt adhesive layer by Joule heating of the metal layer to adhere it to the adherend layer. is there. The metal layer is preferably a conductive metal selected from iron, aluminum, nickel, stainless steel, zinc, lead, zinc, magnesium and alloys thereof, more preferably stainless steel, and particularly preferably aluminum.

As these metal layers, those in the form of film or metal foil can be preferably used. The thickness of the metal layer is preferably 1 μm or more and 1000 μm or less, more preferably 10 μm or more and 500 μm or less, and further preferably 20 μm or more and 100 μm or less. Within the above range, particularly rapid heat generation and optimum heat generation temperature are achieved.

<Thermal coloring layer (D)>
The thermosensitive coloring layer (D) of the present invention is a layer that develops color by heat generated when the adhesive sheet is heated by an electromagnetic induction heating device. For example, it can be composed of a binder resin, a leuco dye, and a color developing agent, and the thermosensitive color developing layer may be formed using a thermosensitive color developing layer coating liquid having a binder resin, a leuco dye, and a color developing agent. it can.

As the binder resin, for example, polyester, polyether, polycarbonate, polyurethane, acryl, epoxy, polyvinyl acetate, polyvinyl butyral, polyvinyl acetals such as polyvinyl acetoacetal, methyl cellulose, ethyl cellulose, cellulose such as cellulose acetate, polyvinyl alcohol, modified Examples thereof include synthetic rubbers such as polyvinyl alcohol, styrene/butadiene copolymer, acrylonitrile/butadiene copolymer, and methyl acrylate/butadiene copolymer. From the viewpoint of coatability and adhesion to a metal layer, polyvinyl alcohol Resin, polyester resin, polyurethane resin, acrylic resin and epoxy resin are preferable.

Examples of leuco dyes include 3,3-bis(p-dimethylaminophenyl)-phthalide, 3,3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide [crystal violet lactone], 3,3 -Bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 4,4'-bis(dimethylaminophenyl)benzhi Drill benzyl ether, N-chlorophenyl leuco auramine, Rhodamine B anilinolactam, Rhodamine B p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, benzoylleuco methylene blue, p-nitrobenzoyl leuco methylene blue, 3-methylspironaphthopyran, 3-ethylspirodinaphthopyran, 3-diethylamino-6-methyl-7-anilinofluorane, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide, 3 -Diethylamino-7-chlorofluorane, 2-(2-chlorophenylamine)-diethylaminofluorane, 2-(2-fluorophenylamino)-6-diethylaminofluorane, 2-(2-fluorophenylamino)-6 -Di-n-butylaminofluorane and the like can be mentioned. These may be used alone or in combination of two or more.

The content of the leuco dye is preferably 10 to 200 parts by mass and more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin. Within the above range, it is easy to disperse in the binder resin, and good color development can be obtained.

Examples of the color developing agent include phenol, p-methylphenol, p-tertiarybutylphenol, p-phenylphenol, α-naphthol, β-naphthol, 4,4′-isopropylidenediphenol [bisphenol A], 4,4. '-Secondary butylidene diphenol, 4,4'-cyclohexylidene diphenol, 4,4'-isopropylidene bis(2-tert-butylphenol), 4,4'-(1-methyl-n-hexylidene)diphenol, 4,4'-isopropylidene dicatechol, 4,4'-pentylidene diphenol, 4,4-isopropylidene bis(2-chlorophenol), phenyl-4-hydroxybenzoate, salicylic acid, 3-phenylsalicylic acid, 5- Methyl salicylic acid, 3,5-di-tert-butyl salicylic acid, 1-oxy-2-naphthoic acid, m-oxybenzoic acid, 4-oxyphthalic acid and the like can be mentioned. These may be used alone or in combination of two or more.

The content of the developer is preferably 50 to 1000 parts by mass, more preferably 100 to 500 parts by mass, relative to 100 parts by mass of the leuco dye. When the content of the color developer is within this range, excellent color development is achieved.

If necessary, the same additives as those mentioned above as the additives for the thermoplastic hot melt adhesive layer can be used in the heat-sensitive color forming layer (D). Examples thereof include antiblocking agents, inorganic fillers, antioxidants, fillers, flame retardants, plasticizers, antistatic agents, light stabilizers, UV absorbers, heavy metal deactivators, and the like.

The thermosensitive coloring layer (D) is prepared by, for example, uniformly dispersing or dissolving a leuco dye and a developer in a binder resin dissolved in an organic solvent or water to prepare a thermosensitive coloring layer coating solution, It can be obtained by applying the working solution to the metal layer (A) and drying. As a device for applying the thermosensitive color developing layer coating liquid, a comma coater, a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater, a reverse roll coater, a blade coater, a gravure coater, a microgravure coater, etc. Are listed. The coating amount of the heat-sensitive color forming layer (D) is preferably about 1 to 100 μm as a dry film thickness, and more preferably 3 to 20 μm.

<Method for producing hot melt adhesive sheet for electromagnetic induction heating>
The method of laminating the metal layer and the thermoplastic hot melt adhesive layer in the hot melt adhesive sheet for electromagnetic induction heating is as follows: (1) thermal lamination or electromagnetic induction heating of the metal layer and the film-shaped thermoplastic hot melt adhesive layer. And (2) a thermoplastic hot melt adhesive is heated and then directly applied to the metal layer by a die method, a spray method, a roll coater method, or the like, (3) a thermoplastic hot melt Adhesives such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone and other ketone solvents, tetrahydrofuran (THF), dioxofuran and other cyclic ether compounds, ethyl acetate, methyl acetate, butyl acetate and other ester compounds, toluene, xylene And the like, and a method of coating on a metal layer after dissolving in an organic compound such as an aromatic compound such as carbitol, cellosolve, alcohol-based compound such as methanol, isopropanol, butanol and propylene.

The thermoplastic hot melt adhesive layer can also be used as a thermoplastic hot melt film (HM film) formed into a film by heat lamination or the like together with a release film.
When the thermoplastic hot melt adhesive layer includes a glass mesh, for example, a film-shaped thermoplastic hot melt adhesive may be arranged on both surfaces of the glass mesh and used as a film by a known heat laminator or the like. ..
The release film at this time may be a conventionally known one.

For the thermosensitive coloring layer (D), for example, a coating liquid for the thermosensitive coloring layer containing the above-mentioned binder resin, leuco dye and developer is prepared, and a comma coater, a gravure coater, a die coater or the like is formed on one surface of the metal layer. It can be obtained by applying the thermosensitive color developing layer coating solution using the composition and sufficiently drying the solvent and water when the coating solution contains the solvent and water. After forming the thermosensitive coloring layer on one surface of the metal layer in advance, a thermoplastic hot melt adhesive layer may be laminated on the other surface by the above-mentioned method, or a thermoplastic hot melt adhesive layer may be formed on one surface of the metal layer. After laminating the melt adhesive layer, a thermosensitive coloring layer may be formed on the other surface.

When a thermosetting adhesive layer is provided between the metal layer and the thermoplastic hot melt adhesive layer, the thermosetting adhesive described above is added to the thermosetting hot melt adhesive layer or the metal layer. When the thermosetting adhesive is coated and the solvent is sufficiently dried, the solvent is sufficiently dried, the metal layer or the thermoplastic hot melt resin layer is pasted, and then the resin is thermoset, thereby hot-melt adhesion for electromagnetic induction heating. You can get a sheet.

<<Adhesive structure>>
The adhesive structure of the present invention comprises an adherend (X) optionally having a primer layer, and at least a metal layer (A), a thermoplastic hot melt adhesive layer (C), and a thermosensitive coloring layer (D). It can be manufactured by adhering the hot melt adhesive sheet for electromagnetic induction heating laminated in this order to the thermoplastic hot melt adhesive layer (C).
That is, the adhesive structure has a laminate (Y) formed from a hot melt adhesive sheet for electromagnetic induction heating and an adherend (X).
Specific examples of the adhesive structure of the present invention will be described later, but the present invention is not limited to these.

For example, referring to FIG. 2, the adhesive structure 20 includes an adherend (X), a thermoplastic hot melt adhesive layer (C), a metal layer (A), and a thermosensitive coloring layer (D) in this order. The laminated body (Y) which has is provided. In addition, as shown in FIG. 3, the adhesive structure has a thermosetting adhesive layer (B) between the thermoplastic hot melt adhesive layer (C) and the metal layer (A), if necessary. You may have.
Further, as shown in FIG. 4, the thermoplastic hot melt adhesive layer (C) may include a mesh between the thermoplastic hot melt adhesive layer 1 and the thermoplastic hot melt adhesive layer 2. ..
Further, as shown in FIG. 5, the adherend (X) may have a primer layer on the surface of the adherend.

<Adherend (X)>
The adherend (X) is an adherend having a primer layer if necessary. By providing the primer layer on the surface of the adherend, the adhesive strength between the adhesive sheet and the adherend can be improved, which is preferable.

[Adherend]
Concrete, wood or the like can be used for the adherend of the present invention. For example, in the case of concrete, a paste obtained by adding water to cement and mixing them together is solidified over time, and may contain fine aggregate such as sand or coarse aggregate such as gravel as aggregate. Concrete hardens due to the dissolution and precipitation reaction of cement. Cement is composed of elements such as calcium, silicon, aluminum and iron. When it comes into contact with water, the calcium ions start to dissolve and the calcium ions in the aqueous solution increase. Silicic acid (SiO ₂ ) and alumina (Al ₂ O ₃ ) which are main components exist as stable substances (polymers) in which respective ions are polymerized with each other and do not react with calcium ions. However, in cement, silicate ions and aluminum ions (alumina-ions) are relatively easy to react and exist in the form of monomers, and the surrounding calcium ions are leached out, so that they are dissolved into the solution and the calcium ions are dissolved. Cement hydrate (C—S—H: ettringite), which is difficult to dissolve in water, is generated by reacting with water molecules and water molecules, and excess calcium ions are precipitated as calcium hydroxide. The hydrate particles bond to each other and begin to harden.
The bond between particles is considered to be held by an intermolecular attractive force or a hydrogen bond, and C-S-H is a fine bond of 0.1 μm or less, unlike calcium hydroxide, and is a particle per unit volume. Since the bonding area between them is extremely large, it exhibits a high bonding force and the strength of the cured product.
The adherend of the present invention includes cement cemented with water and solidified, mortar mixed with cement, water and fine aggregate (sand), and cement, water and aggregate (fine aggregate (sand)). It is possible to use concrete, coniferous wood, hardwood, or other general timber or plywood to which timber is laminated, particle chips or MDF in which wood chips or pulp are hardened, by mixing and agglomerate with coarse aggregate (gravel).

[Primer layer]
The primer layer of the present invention is present between the adherend and the thermoplastic hot melt adhesive layer (C), and is coated with the primer even when there are cracks or irregularities on the surface of the adherend. Thus, the surface of the adherend can be easily and uniformly adjusted to improve the adhesive strength with the thermoplastic hot melt adhesive layer (C).
Examples of the resin forming the primer layer include polyurethane, epoxy, acrylic ester copolymer, styrene-butadiene rubber, ethylene vinyl acetate copolymer, emulsion such as polyamide and polyester, or latex, but polyurethane resin, Epoxy resin or acrylic resin is preferable, and acrylic resin is more preferable. These primer layer forming resins are used alone or in combination of two or more kinds. The thickness of the primer layer is preferably about 0.1 mm to 4 mm.

The primer used for the primer layer is preferably a two-liquid mixed type. It cures within several hours after coating, more preferably within several tens of minutes. In order to shorten the curing time, if it is a thermosetting resin, it may be heated, or if it is anaerobic curing, it may be used by adhering the film to the coated surface and peeling off the film after curing.

The primer used in the primer layer may be used in combination with an inorganic filler, if necessary. Examples of the inorganic filler include particles such as metal, metal oxide and metal hydroxide, and fibrous particles. Specifically, glass fiber, carbon fiber, calcium silicate, calcium titanate, aluminum borate fiber, glass flakes, talc, kaolin, mica, hydrotalcite, calcium carbonate, zinc carbonate, zinc oxide, monohydrogen phosphate. Calcium, wollastonite, silica, zeolite, alumina, boehmite, aluminum hydroxide, titanium oxide, silicon oxide, magnesium oxide, calcium silicate, alumina sodium silicate, magnesium silicate, carbon nano-tube, graphite, copper, silver, aluminum, nickel , Iron, calcium fluoride, mica, montmorillonite, apatite and the like.

The adherend (X) can be obtained by applying a resin, which is a primer, to an adherend such as concrete with a brush or a roll and sufficiently drying and curing, but not limited to this method. The coating amount of the primer resin depends on the type of concrete or thermoplastic hot melt adhesive, but is 10 g/m ² or more and 1,000 g/m ² or less, and preferably 50 g/m ² or more and 500 g/m ² or less. preferable.

<Manufacturing method of adhesive structure, peeling method>
The adhesive structure of the present invention is a known adhesion method such as thermal lamination, electromagnetic induction heating method, etc. for the adherend (X) and the thermoplastic hot melt adhesive layer (C) of the hot melt adhesive sheet for electromagnetic induction heating. It can be glued and obtained. The bonding method can be appropriately selected depending on the presence or absence of an adherend and the thickness of the adherend. Since the adhesive structure of the present invention has a metal layer, it is particularly suitable for adhesion by an electromagnetic induction heating method. There is.
In this way, an adhesive structure having the laminate (Y) formed from the electromagnetic induction heating hot melt adhesive sheet and the adherend (X) can be obtained.
Further, the adherend (X) or the laminated body (Y) is peeled off by using the electromagnetic induction heating method from the adherend (X) or the outside of the adherend (X) as in the case of the adhesion. You can

Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto. In the examples, “parts” and “%” represent “parts by mass” and “mass %”, respectively.

<Preparation of adherend (concrete)>
(Preparation of concrete 1: Cement paste)
After thoroughly mixing 70% by mass of cement and 30% by mass of tap water, the mixture was put in a wooden frame and allowed to stand for 30 days or longer to prepare concrete 1.

(Preparation of concrete 2: concrete)
After thoroughly mixing 15% by mass of cement, 30% by mass of fine aggregate (sand) and 45% by mass of coarse aggregate (gravel), 10% by mass of tap water was mixed and stirred, and then placed in a wooden frame and allowed to stand for 30 days or more. Then, concrete 2 was prepared.

<Adjustment of primer 1>
Compound A hard rock IIDK550-003RA (methacrylic ester, manufactured by Denka Corporation) and agent B hard rock IIDK550-003RB (methacrylic ester, manufactured by Denka Corporation) at a mass ratio of 1/1. Primer 1 was prepared by mixing.

<Production of adherend (X)>
(Production of adherends (X-1) to (X-3))
Using the concrete and the primer shown in Table 1, the surface of the concrete is sufficiently ground with a sander, dust on the surface, concrete dregs, etc. are removed with a vacuum cleaner, and then the primer is applied onto the concrete with a brush, The adherends (X-1) and (X-2) were obtained. After the primer 1 (acrylic type) was applied, a release-treated PET film was applied, the anaerobic reaction was promoted by blocking air, and the primer 1 was allowed to stand for 1 week or more to be sufficiently cured. In the adherend (X-3), the surface of concrete was sufficiently ground with a sander, but the primer was not applied.

<Mesh>: The materials shown below were used as the mesh.
Mesh 1: Biaxial laminated mesh CLENET E-12100 (Kurashiki Spinning Co., Ltd.)

<Preparation of thermoplastic hot melt film (HM film)>
(Thermoplastic hot melt film (HM film) 1 to 6)
Using an extrusion laminator, the thermoplastic hot-melt adhesive resin shown in Table 2 was laminated on a PET film (thickness: 25 μm) that had been subjected to a mold release while changing the film thickness, and was wound by a winding section to obtain a thermoplastic hot melt. HM films 1 to 6 having a melt adhesive layer were produced. The processing conditions are shown below.

Extrusion Laminator: 400M/M Test EXT Laminator Die Made by Musashino Kikai Resin Temperature Directly Under Die: 140-240°C (Adjusted appropriately according to MFR of resin)
Processing speed: 30 m/min T-die width: 400 mm
Cooling roll surface temperature: 20°C

(Thermoplastic hot melt film (HM film) 7)
The HM film 1, the mesh 1, and the HM film 1 obtained by the above method were laminated in this order using a pressure roll having a surface temperature of 100° C., and the HMs on both sides of the mesh 1 were bonded together. The HM film 7 was produced by integrating the film and the mesh.

<Preparation of thermosensitive coloring layer coating liquid>
(Preparation of thermosensitive coloring layer coating liquid 1)
Polyvinyl alcohol 10% aqueous solution 100 parts (binder resin), 3-diethylamino-6-methyl-7-anilinofluorane 5 parts (leuco dye), 4,4'-isopropylidenediphenol [bisphenol A] 10 parts (visible) (Coloring agent) was put in a container, glass beads having a diameter of 3 mm were added and dispersed for 60 minutes by a paint shaker, and then the glass beads were removed to prepare a thermosensitive coloring layer coating solution 1.

(Preparation of thermosensitive coloring layer coating liquid 2)
In the same manner as in the thermosensitive coloring layer coating liquid 1, except that 10 parts of 3-diethylamino-6-methyl-7-anilinofluorane and 100 parts of 4,4′-isopropylidene diphenol [bisphenol A] were used, A thermosensitive coloring layer coating solution 2 was prepared.

(Preparation of thermosensitive coloring layer coating liquid 3)
In the same manner as in the thermosensitive color developing layer coating liquid 1, except that 1 part of 3-diethylamino-6-methyl-7-anilinofluorane and 2 parts of 4,4′-isopropylidenediphenol [bisphenol A] were used, A thermosensitive color developing layer coating liquid 3 was prepared.

(Preparation of thermosensitive coloring layer coating liquid 4)
In the same manner as in the thermosensitive color developing layer coating liquid 1, except that 15 parts of 3-diethylamino-6-methyl-7-anilinofluorane and 150 parts of 4,4′-isopropylidenediphenol [bisphenol A] were used, A thermosensitive coloring layer coating solution 4 was prepared.

(Preparation of thermosensitive coloring layer coating liquid 5)
A thermosensitive color developing layer coating liquid 5 was prepared in the same manner as the thermosensitive color developing layer coating liquid 1, except that the leuco dye was 3,3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide.

<Adjustment of thermosetting adhesive>
(Adjustment of thermosetting adhesive 1)
The main agent TM-76 and the curing agent CAT-RT85 were mixed in a mass ratio of 100/7, and diluted with ethyl acetate so that the solid content was 30%.
Main agent TM-K76 (polyester resin, non-volatile content 51%, manufactured by Toyo Morton Co., Ltd.)
-Curing agent: CAT-RT85 (polyisocyanate, non-volatile content 70%, manufactured by Toyo Morton Co., Ltd.)

(Adjustment of thermosetting adhesive 2)
The main agent LIS-073-50U and the curing agent CR-001 were mixed in a mass ratio of 17/3, and diluted with ethyl acetate so that the solid content was 30%.
・Main agent LIS-073-50U (urethane resin, nonvolatile content 30%, manufactured by Toyo Morton Co., Ltd.)
Curing agent: CR-001 (aliphatic polyisocyanate, nonvolatile content 70%, manufactured by Toyo Morton Co., Ltd.)

[Example 1]
The thermoplastic hot melt adhesive layer (C-1) of the HM film 1 and an aluminum foil having a thickness of 20 μm were attached to each other using a pressure roll heated to a surface temperature of 120° C. to obtain a laminate 1a. The surface of the laminate 1a on which the HM film 1 of the aluminum foil is not laminated is coated with a gravure coater so that the film thickness after drying is 5 μm, dried, and hot for electromagnetic induction heating. A melt adhesive sheet 1 was obtained.

The release-treated PET film of the hot melt adhesive sheet 1 for electromagnetic induction heating is peeled off to expose the thermoplastic hot melt adhesive layer (C-1), and the primer layer of the adherend (X-1) and electromagnetic induction. The hot melt adhesive sheet 1 for electromagnetic induction and the adherend (X-1) were made to have a thickness of 5 mm so that the thermoplastic hot melt adhesive layer (C-1) of the hot melt adhesive sheet 1 for heating was in contact with each other. It was sandwiched between a wooden board and an electromagnetic induction heating device (all-over adhesive device manufactured by Achilles Co., Ltd.) and pressed against the wooden board, and heated at 37 kHz for 3 seconds. After the heating is finished, it is left to stand for 24 hours until the temperature returns to room temperature, and the laminated body (Y) having the constitution of the thermoplastic hot melt adhesive layer (C)/metal layer (A)/thermosensitive coloring layer (D) is adhered. An adhesive structure 1 having a body (X) was obtained.

[Examples 2 to 12, 15 to 17, Comparative Example 1]
Similar to the adhesive sheet 1 for electromagnetic induction heating, except that the thermoplastic hot melt adhesive layer (C), the metal layer (A), and the thermosensitive coloring layer (D) were changed to the materials and constitutions shown in Table 3. Electromagnetic induction heating adhesive sheets 2 to 12, 15, and 16 were obtained.

Thereafter, bonded structures 2 to 12 and 15 to 18 were obtained in the same manner as the bonded structure 1 of Example 1 except that the materials shown in Table 3 were changed.
In addition, in Example 15, one of the release-treated PET films of the HM film 7 was peeled off and used by being attached to an aluminum foil.

[Example 13]
The thermosetting adhesive 1 was applied to the HM film 1 with a gravure coater so that the applied amount was 3 to 10 g/m ² (Dry), and dried to obtain a laminate 2a. At this time, the temperature of the adhesive was heated to about 30 to 45° C., and the drying time was 80° C. for 1 minute.
Next, the surface of the HM film 1 coated with the thermosetting adhesive 1 and the aluminum foil having a thickness of 20 μm were bonded together using a pressure roll having a surface temperature of 120° C. to obtain a laminated body 2b.
On the surface of the laminated body 2b on which the HM film of the aluminum foil is not laminated, the thermosensitive coloring layer coating solution 1 is applied by a gravure coater so that the film thickness after drying is 5 μm, dried, and hot melt for electromagnetic induction heating. An adhesive sheet 13 was obtained.

After that, the thermoplastic hot melt adhesive layer (C)/thermosetting adhesive layer (B)/metal layer (in the same manner as the adhesive structure 1 of Example 1 except that the materials shown in Table 3 were changed). A laminated structure (Y) having a structure of (A)/thermosensitive coloring layer (D) and an adherend structure 13 having an adherend (X) were obtained.

[Example 14]
An electromagnetic induction heating adhesive sheet 14 was obtained in the same manner as the electromagnetic induction heating adhesive sheet 13 except that the thermosetting adhesive 1 was changed to the thermosetting adhesive 2.

Then, an adhesive structure 14 was obtained in the same manner as the adhesive structure 1 of Example 1 except that the materials shown in Table 3 were changed.

<Evaluation of bonded structure>
With respect to the obtained adhesive structure, the adhesive strength between the concrete layer and the metal layer was evaluated. The results are shown in Table 4.

[Adhesive strength (JIS K6859 compliant)]
The adhesive strength was measured by using a tensile tester (manufactured by A&A Co., Ltd., trade name RTA-100) to measure the shear strength at a peeling speed of 300 mm/min (measurement temperature: 23° C., humidity 50%). The following criteria were used for evaluation. If the evaluation is other than "C", there is no particular problem in actual use.

"A": 10 N/cm ² or more (including substrate destruction)
"B": 5 N/cm ² or more and less than 10 N/cm ² "C": less than 5 N/cm ²

[Visibility after heating]
With respect to the obtained bonded structure, the visibility of the heated portion was evaluated according to the following criteria. There is no particular problem in actual use unless the evaluation is “x”.

"○": The heated part is clearly colored and can be easily identified.
"△": The heated part is lightly colored and can be identified "x": There is no change in the heated part and it cannot be identified

[Peelability]
When each of the obtained bonded structures was heated under the same electromagnetic induction heating conditions as in the bonding step, each could be easily peeled from the adherend.

As shown in Table 3, the adhesive structure using the adhesive sheet of the present invention showed excellent adhesive strength. Further, by providing the thermosensitive coloring layer, it was confirmed that the heated portion was easy to identify and had excellent workability (Examples 1 to 17).

10 Hot Melt Adhesive Sheet for Electromagnetic Induction Heating 20 Adhesive Structure A Metal Layer (A)
B Thermosetting adhesive layer (B)
C thermoplastic hot melt adhesive layer (C)
C1 thermoplastic hot melt adhesive layer 1
C2 thermoplastic hot melt adhesive layer 2
C3 mesh D Thermosensitive coloring layer (D)
X adherend (X)
X1 Adherend X2 Primer layer Y Laminate (Y)

Claims (8)

A hot melt adhesive sheet for electromagnetic induction heating, comprising a thermoplastic hot melt adhesive layer (C), a metal layer (A), and a thermosensitive coloring layer (D) laminated in this order. The hot melt for electromagnetic induction heating according to claim 1, further comprising a thermosetting adhesive layer (B) between the metal layer (A) and the thermoplastic hot melt adhesive layer (C). Adhesive sheet. The hot melt adhesive sheet for electromagnetic induction heating according to claim 1 or 2, wherein the thermoplastic hot melt adhesive layer (C) includes a mesh. The hot-melt adhesive sheet for electromagnetic induction heating according to any one of claims 1 to 3, wherein the thermosensitive coloring layer (D) contains a leuco dye and a developer. An adhesive structure comprising a laminate (Y) formed by using the hot melt adhesive sheet for electromagnetic induction heating according to any one of claims 1 to 4, and an adherend (X). The adherend (X) has a primer layer on the surface of the adherend, The adhesive structure according to claim 5. The hot melt adhesive sheet for electromagnetic induction heating according to any one of claims 1 to 4 is heated by an electromagnetic induction heating device to bond the hot melt adhesive sheet for electromagnetic induction heating and the adherend (X). A method for manufacturing a characteristic bonded structure. The adhesive structure according to claim 5 or 6 is heated by an electromagnetic induction heating device to soften or melt the thermoplastic hot melt adhesive layer (C) in a solid state, and to laminate it with an adherend (X). A method of peeling off the body (Y).