Thermoplastic multilayer adhesive film

Abstract

The present invention addresses the problem of obtaining a thermoplastic multilayer adhesive film capable of adhering to each other adherends that are otherwise difficult to adhere with one adhesive in a manner such that the adhesive strength is high so that sufficient tensile shear adhesive strength and 90-degree peel adhesive strength can be exhibited. As a solution, provided is a thermoplastic multilayer adhesive film having the following resin layer A and the following resin layer B, resin layer A: a layer containing a carboxylic acid-modified polyolefin and / or ionomer, and resin layer B: a layer containing a polymer and a crosslinking agent, the polymer is one or more selected from the group consisting of a carboxyl-modified styrene-butadiene copolymer, a carboxyl-modified acrylonitrile-styrene-butadiene copolymer, and a carboxyl-modified methyl methacrylate-butadiene copolymer.

Description

Technical Field

[0001] The invention relates to a thermoplastic multilayer adhesive film. Background Art

[0002] As described in Patent Document 1, in order to achieve good adhesion to two adherends when sandwiched between two adherends formed of different materials, an adhesive resin laminate is known, which includes: a layer containing a modified polyolefin resin and an epoxy crosslinking agent and a layer containing a polyolefin-based resin. It is also known that the obtained laminate has a high peel strength when subjected to T-peeling.

[0003] Such sheet adhesives for bonding different types of materials are known, but according to the invention described in Patent Document 1, the adhesive strength is limited to the extent that the peel strength can be measured by T-peeling, and for example, the adhesive strength is not sufficient to cause cohesive failure between layers in the adhesive resin laminate after bonding. In addition, it is difficult to thermally bond ABS resin, polycarbonate resin, acrylic resin, and vinyl chloride resin as adherends.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-131553 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The technical problem of the present invention is to obtain a thermoplastic multilayer adhesive film that can heat-melt and thermally bond adherends that are difficult to bond with a single adhesive in a manner that exhibits a high adhesive strength sufficient to exhibit tensile shear adhesive strength and 90-degree peel adhesive strength.

[0009] Solutions for solving problems

[0010] The present inventors have conducted intensive studies to solve the above-mentioned technical problems, and as a result, have found that the problems can be solved by the following means, thereby completing the present invention.

[0011] 1. A thermoplastic multilayer adhesive film comprising the following resin layer A and the following resin layer B.

[0012] Resin layer A: a layer containing a carboxylic acid-modified polyolefin and / or an ionomer.

[0013] Resin layer B: a layer containing a polymer and a crosslinking agent, wherein the polymer is at least one selected from a carboxyl-modified styrene-butadiene copolymer, a carboxyl-modified acrylonitrile-styrene-butadiene copolymer, and a carboxyl-modified methyl methacrylate-butadiene copolymer.

[0014] 2. The thermoplastic multilayer adhesive film according to 1, wherein the crosslinking agent contained in the resin layer B is a crosslinking agent containing an oxazoline group or a carbodiimide group.

[0015] 3. The thermoplastic multilayer adhesive film according to 1 or 2, wherein the total content of the carboxylic acid-modified polyolefin and the ionomer in the resin layer A is 8.0% by weight or more.

[0016] 4. The thermoplastic multilayer adhesive film according to any one of 1 to 3, wherein in the resin layer B, the content of the crosslinking agent is 1.0 to 80.0 parts by weight relative to a total of 100 parts by weight of one or more selected from the group consisting of a carboxyl-modified styrene-butadiene copolymer, a carboxyl-modified acrylonitrile-styrene-butadiene copolymer, and a carboxyl-modified methyl methacrylate-butadiene copolymer.

[0017] 5. A laminated body obtained by heat-bonding the following adherend A to the surface of the resin layer A and heat-bonding the following adherend B to the surface of the resin layer B of the thermoplastic multilayer adhesive film according to any one of 1 to 4.

[0018] Adherend A: at least one selected from metal, polypropylene resin, polyethylene resin, polyamide resin and thermosetting resin.

[0019] Adherend B: at least one selected from ABS resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin and amorphous polyester resin.

[0020] 6. A bonding method, wherein the following adherend A is overlapped on the surface of the resin layer A of the thermoplastic multilayer adhesive film described in any one of 1 to 5, and the following adherend B is overlapped on the surface of the resin layer B, and the resin layers A and B are heated and melted to perform thermal bonding.

[0021] Adherend A: at least one selected from metal, polypropylene resin, polyethylene resin, polyamide resin and thermosetting resin.

[0022] Adherend B: at least one selected from ABS resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin and amorphous polyester resin.

[0023] 7. A method comprising: a step of overlapping the following adherend A on the surface of the resin layer A of the thermoplastic multilayer adhesive film as described in any one of 1 to 6, heating and bonding, and after this step, a step of forming a layer formed by the following adherend B melted by heating on the surface of the resin layer B of the thermoplastic multilayer adhesive film.

[0024] Alternatively, the method includes: a step of overlapping the following adherend B on the surface of the resin layer B of the thermoplastic multilayer adhesive film as described in any one of 1 to 6, heating and bonding, and after this step, a step of forming a layer formed by the following adherend A heated and melted on the surface of the resin layer A of the thermoplastic multilayer adhesive film.

[0025] Adherend A: at least one selected from metal, polypropylene resin, polyethylene resin, polyamide resin and thermosetting resin.

[0026] Adherend B: at least one selected from ABS resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin and amorphous polyester resin.

[0027] 8. A method for producing a thermoplastic multilayer adhesive film, wherein an aqueous composition containing the following latex and a crosslinking agent is applied to a resin layer A composed of a layer containing a carboxylic acid-modified polyolefin or ionomer and subjected to surface treatment as required, and the water is dried at a temperature at which the resin layer A does not soften or melt to form a resin layer B, wherein the latex is one or more selected from a carboxyl-modified styrene-butadiene copolymer latex, a carboxyl-modified acrylonitrile-styrene-butadiene copolymer latex and a carboxyl-modified methyl methacrylate-butadiene copolymer latex.

[0028] Effects of the Invention

[0029] According to the present invention, a thermoplastic multilayer adhesive film can be obtained, which can bond adherends that are difficult to be thermally bonded by a film-like or sheet-like adhesive with a high adhesive force that can exhibit sufficient tensile shear adhesive strength. In addition, the following effects can be achieved: a method for producing a thermoplastic multilayer adhesive film and a method for bonding with a strong adhesive force using a thermoplastic multilayer adhesive film can be obtained. DETAILED DESCRIPTION

[0030] The present invention is based on a thermoplastic multilayer adhesive film, which has a resin layer A and a resin layer B, each serving as an adhesive layer.

[0031] When the thermoplastic multilayer adhesive film is formed by laminating one resin layer A and one resin layer B, the adherend A can be laminated and bonded on the resin layer A side, and the adherend B can be laminated and bonded on the resin layer B side.

[0032] <Resin layer A>

[0033] The resin layer A in the present invention is a layer containing a carboxylic acid-modified polyolefin and / or an ionomer.

[0034] In the resin layer A, the carboxylic acid-modified polyolefin and the ionomer may be used by appropriately mixing ethylene-based resins, propylene-based resins, and butene-based resins.

[0035] The total content of the carboxylic acid-modified polyolefin and the ionomer in the resin layer A is 8.0 wt % or more, preferably 25.0 wt % or more, more preferably 40.0 wt % or more, and further preferably 50.0 wt % or more. When the total content of the carboxylic acid-modified polyolefin and the ionomer is less than 8.0 wt %, it is difficult to obtain adhesion to the adherend A, and interfacial peeling with the resin layer B is likely to occur, making it difficult to obtain the expected adhesive strength (sufficient adhesion may not be obtained).

[0036] The thickness of the resin layer A is preferably 7 μm or more, more preferably 20 μm or more, and further preferably 40 μm or more, and is preferably 250 μm or less, more preferably 150 μm or less, and further preferably 100 μm or less.

[0037] (Carboxylic acid modified polyolefin)

[0038] Carboxylic acid-modified polyolefin is a material obtained by graft polymerization of an unsaturated carboxylic acid or its anhydride on a base polyolefin. As the base polyolefin, at least one selected from ethylene resins, propylene resins and butene resins can be listed, and preferably at least one selected from ethylene resins and propylene resins can be listed.

[0039] The ethylene resin as the base polyolefin of the carboxylic acid-modified polyolefin may be, for example, at least one selected from low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ultra-high-density polyethylene, and copolymers of ethylene and other monomers (for example, ethylene / vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / acrylate copolymer, ethylene / methacrylate copolymer, ethylene / butene-1 copolymer, ethylene / propylene / butene-1 copolymer, ethylene / α-olefin copolymer having 3 to 12 carbon atoms, ethylene / non-conjugated diene copolymer, etc.).

[0040] When the adherend A has a low melting point such as low-density polyethylene, the carboxylic acid-modified polyolefin used in the present invention is preferably a material having a melting point equal to or lower than that of the adherend A, such as an LDPE substrate or an EVA substrate.

[0041] Examples of the propylene resin as the base polyolefin of the carboxylic acid-modified polyolefin include at least one selected from random polypropylene, block polypropylene, homopolypropylene, and copolymers of propylene and other monomers.

[0042] Examples of the butene-based resin as the base polyolefin of the carboxylic acid-modified polyolefin include at least one selected from polybutene-1 and a copolymer of butene-1 and an α-olefin.

[0043] As unsaturated carboxylic acids for carboxylic acid modification of polyolefins, for example, maleic acid, itaconic acid, fumaric acid, acrylic acid, and methacrylic acid can be cited. As derivatives of the above unsaturated carboxylic acids, maleic acid monoesters, maleic acid diesters, maleic anhydride, itaconic acid monoesters, itaconic acid diesters, itaconic anhydride, fumaric acid monoesters, fumaric acid diesters, fumaric anhydride, 1,2,3,6-tetrahydrophthalic acid, methylene succinic acid, citraconic acid, citraconic anhydride, alkyl acrylates such as methyl acrylate, and alkyl methacrylates such as methyl methacrylate can be cited. Among them, maleic anhydride and derivatives of maleic anhydride are preferred from the viewpoint of adhesion. As unsaturated carboxylic acids, one or a mixture of two or more thereof can be used.

[0044] The acid modification amount of the carboxylic acid-modified polyolefin (the amount of the structural unit derived from the grafted unsaturated carboxylic acid or unsaturated carboxylic acid derivative) depends on the type of the grafted unsaturated carboxylic acid or unsaturated carboxylic acid derivative. For example, in the case of maleic anhydride, it is preferably 0.01% by weight or more, more preferably 1.0% by weight or more, from the viewpoint of adhesion. On the other hand, from the viewpoint of film forming properties, it is preferably 10.0% by weight or less, more preferably 5.0% by weight or less.

[0045] The method for obtaining the carboxylic acid-modified polyolefin is not limited, and for example, the following method can be used: a resin composition comprising 100 parts by weight of a polyolefin, 0.05 to 5 parts by weight of an unsaturated carboxylic acid and / or an unsaturated carboxylic acid derivative, and 0.05 to 5 parts by weight of an organic peroxide is melt-kneaded, and the unsaturated carboxylic acid and / or an unsaturated carboxylic acid derivative is grafted onto the polyolefin.

[0046] Examples of the organic peroxide include diisopropylbenzene peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxide)hexyne-3,1,3-bis(tert-butylperoxide isopropyl)benzene, 1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxide)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl perbenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butyl cumene peroxide. As the above-mentioned component, 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane and 2,5-dimethyl-2,5-di(tert-butylperoxide)hexyne-3-yl are preferred from the viewpoint of adhesiveness. As the above-mentioned component, one kind or a mixture of two or more kinds thereof may be used.

[0047] The amount of the organic peroxide to be added is 0.05 parts by weight or more, preferably 0.2 parts by weight or more, and more preferably 0.5 parts by weight or more, relative to 100 parts by weight of the polyolefin, from the viewpoint of adhesion. In addition, from the viewpoint of controlling the decrease in melt viscosity during acid modification, it is 5 parts by weight or less, preferably 4 parts by weight or less, and more preferably 3 parts by weight or less.

[0048] Examples of the carboxylic acid-modified polypropylene-based resin include BYNEL manufactured by Dow Chemical, UMEX manufactured by Sanyo Chemical Co., Ltd., ADMER manufactured by Mitsui Chemicals, Inc., and MODIC manufactured by Mitsubishi Chemical Co., Ltd.

[0049] As the carboxylic acid-modified polypropylene resin, for example, there can be listed: substances formed by introducing carboxyl groups into propylene homopolymers; copolymers (including block copolymers and random copolymers) of propylene and other small amounts of α-olefins (for example, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene, etc.). Among polypropylenes, polypropylene with a melting point that is not too high is preferred, preferably below 165°C, more preferably below 155°C, and further preferably below 145°C. In addition, from the perspective of heat resistance, it is preferably above 125°C. As such a polypropylene resin, for example, a propylene homopolymer with high stereoregularity (the isotactic pentad fraction is generally 96 mol% or more, preferably 98 mol% or more) can be listed. As the above-mentioned polypropylene resin, one or a mixture of two or more thereof can be used.

[0050] Examples of carboxylic acid-modified polyethylene resins include ADMER manufactured by Mitsui Chemicals, MODIC manufactured by Mitsubishi Chemical, OREVAC and LOTADER manufactured by SKFP, and BYNEL manufactured by Dow Chemical. Generally, carboxylic acid-modified polyethylene resins have a lower melting point than carboxylic acid-modified polypropylene resins, and thus can be melted and thermally bonded at a lower temperature.

[0051] (Ionomer)

[0052] Ionomers are special resins in which the carboxyl groups of ethylene-methacrylic acid copolymers and ethylene-acrylic acid copolymers are neutralized with metal ions such as sodium, zinc, and potassium. When the ionomer is melted by heating during thermal bonding, the ionic bonds between the carboxyl groups and the metal ions are relaxed and activated, thereby reacting with the crosslinking agent contained in the resin layer B.

[0053] The polymer having a carboxyl group may be a polymer having a carboxyl group obtained by copolymerizing an unsaturated carboxylic acid monomer with other monomers. In addition, it may be the above-mentioned carboxylic acid-modified polyolefin. In addition, one ionomer may be used, or multiple ionomers may be used.

[0054] Examples of such unsaturated carboxylic acid monomers include (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, and itaconic anhydride.

[0055] In addition, as other monomers, (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, isooctyl (meth)acrylate, and diethyl maleate, vinyl esters such as vinyl acetate and vinyl propionate, and olefins such as ethylene, propylene, and butene can be used.

[0056] Furthermore, as the metal ion that forms a salt with the carboxyl group of the polymer having a carboxyl group and constitutes an ionomer, ions of alkali metals such as lithium, sodium, potassium, and divalent metals such as magnesium, calcium, zinc, cobalt, nickel, copper, and lead are preferred. Alkali metal ions are particularly preferred.

[0057] As the ionomer, for example, there is HIMILAN manufactured by DOW-MITSUIPOLY CHEMICALS.

[0058] (Other resins)

[0059] The resin layer A may contain other resins other than carboxylic acid-modified polyolefins and non-ionomers within a range that does not impair the effects of the present invention. Examples of such resins include polyolefin resins such as the above-mentioned ethylene resins, propylene resins, and butene resins.

[0060] As these polyolefin-based resins, various polyolefins shown as the base polymer of the above-mentioned carboxylic acid-modified polyolefin may be used as they are without being modified with carboxylic acid.

[0061] When the resin layer A contains these other resins, the content of the other resins is preferably 92% by weight or less, and more preferably 50% by weight or less, based on the entire resin layer A.

[0062] <Resin layer B>

[0063] (Carboxyl-modified styrene-butadiene copolymer, carboxyl-modified acrylonitrile-styrene-butadiene copolymer and carboxyl-modified methyl methacrylate-butadiene copolymer)

[0064] The resin layer B in the present invention is a layer containing one or more polymers selected from the group consisting of carboxyl-modified styrene-butadiene copolymers, carboxyl-modified acrylonitrile-styrene-butadiene copolymers, and carboxyl-modified methyl methacrylate-butadiene copolymers.

[0065] The resin layer B is a layer of a resin containing a copolymer obtained by modifying a copolymer containing styrene and / or butadiene as main monomer components with a carboxyl group. The copolymer may also be obtained by further copolymerizing styrene and / or butadiene with acrylonitrile.

[0066] Furthermore, the resin may be a copolymer containing a monomer copolymerizable with an alkyl (meth)acrylate such as methyl (meth)acrylate and ethyl (meth)acrylate; an olefin such as ethylene and propylene; (meth)acrylamide; a vinyl aromatic compound; or a conjugated diene compound such as butadiene.

[0067] This copolymer is a copolymer modified with a carboxyl group, and may also be a copolymer obtained by copolymerizing a monomer having a carboxyl group such as (meth)acrylic acid.

[0068] The carboxyl-modified styrene-butadiene copolymer, carboxyl-modified acrylonitrile-styrene-butadiene copolymer and carboxyl-modified methyl methacrylate-butadiene copolymer contained in the resin layer B are resins different from the carboxylic acid-modified polyolefin or ionomer contained in the resin layer A.

[0069] Carboxyl-modified styrene-butadiene copolymer, carboxyl-modified acrylonitrile-styrene-butadiene copolymer and carboxyl-modified methyl methacrylate-butadiene copolymer are preferably supplied in the form of latex, and are also preferably supplied in the form of aqueous solution or aqueous dispersion. The coating liquid used to form the resin layer B is preferably aqueous. If it is in the form of latex, it is easy to increase the concentration of the resin compared to when it is a solution, and it is easy to mix when mixing the crosslinking agent aqueous solution, and the workability is excellent. Therefore, it is easy to form a resin layer B in which the crosslinking agent is uniformly dispersed. In addition, the resin phase is originally separated from the aqueous phase, so heating and drying when forming the resin layer B can be performed earlier. The formed resin layer B is formed by the resin of the dispersed resin particles derived from the latex and the crosslinking agent uniformly present therein, and the crosslinking agent is also uniformly present inside the resin on the surface of the resin layer B that is in contact with the resin layer A.

[0070] It should be noted that in latex, in order to improve the film strength when the film is made, a crosslinking agent (such as an internal crosslinking agent such as a vulcanizing agent that acts on the double bonds of the copolymer) for crosslinking the resin and the groups other than the carboxyl group is sometimes contained. The crosslinking agent originally contained in such latex can be contained separately from the following crosslinking agent. In addition, the latex can also contain a neutralizing agent and a surfactant.

[0071] As the latex of the above-mentioned carboxyl-modified styrene-butadiene copolymer, carboxyl-modified acrylonitrile-styrene-butadiene copolymer and carboxyl-modified methyl methacrylate-butadiene copolymer, it can be selected from latex SB and PCL manufactured by JSR Corporation, NALSTAR and SMARTTEX manufactured by NIPPON A&L, Nipol of SBRLATEX manufactured by Nippon ZEON Corporation, Nipol of NBR LATEX, LACSTAR manufactured by DIC Corporation, and the like.

[0072] The thickness of the resin layer B is preferably 2 μm or more, more preferably 10 μm or more, and further preferably 13 μm or more, and is preferably 200 μm or less, more preferably 100 μm or less, and further preferably 50 μm or less.

[0073] (Crosslinking agent)

[0074] The resin layer B contains a crosslinking agent that can react with the carboxyl groups of the resins contained in the resin layer A and the resin layer B.

[0075] At this time, as an aqueous crosslinking agent composition, when the resin constituting the resin layer B is in the form of a latex, an aqueous solution, or an aqueous dispersion as an aqueous dispersed copolymer resin, when a crosslinking agent is added thereto, it is desirable that the crosslinking agent itself is also a crosslinking agent in the form of an aqueous solution, an aqueous emulsion, or an aqueous dispersion. Moreover, one or more of the three types of crosslinking agents in the form of an aqueous solution, an aqueous emulsion, and an aqueous dispersion can be used. In particular, it is more preferred to use a crosslinking agent in the form of an aqueous solution and a crosslinking agent in the form of an aqueous dispersion. The mixing ratio of the solid content of the crosslinking agent in the form of an aqueous solution and the crosslinking agent in the form of an aqueous dispersion is preferably 2:8 to 8:2, more preferably 3:7 to 7:3, and further preferably 4:6 to 6:4.

[0076] Furthermore, it is desirable to add a large amount of crosslinking agent to the resin layer B to such an extent that it can crosslink not only the carboxyl groups contained in the resin layer B but also the carboxyl groups contained in the resin layer A. Crosslinking in the resin layer B is performed by heating during film formation and drying during coating. The formed resin layer B forms a crosslinked structure in the layer. At the same time, a large amount of unreacted crosslinking agent is contained in the resin layer B. This unreacted crosslinking agent reacts with the resin in the resin layer A or crosslinks the interface between the resin layer A and the resin layer B by heating when bonding with the subsequent adherend, and a crosslinking reaction also proceeds in the resin layer B.

[0077] During thermal bonding, both the resin layer A and the resin layer B need to be melted, softened, and liquidized by heating.

[0078] By heating during thermal bonding, the carboxyl groups of the resin layer A and the resin layer B react with the unreacted crosslinking agent in the resin layer B, thereby significantly improving the interface strength and obtaining a very strong tensile shear bonding strength.

[0079] It should be noted that, when a plurality of cross-linking agents having different cross-linking temperatures are used in combination, in order to exert the adhesiveness when the resin layer B is laminated on the resin layer A, the resin layer B is cured by heating at a low temperature with the cross-linking agent having a low cross-linking temperature. Next, an adherend is overlapped on the resin layer B side of the laminate of the formed resin layer A and the resin layer B, and the laminate is heated at a high temperature to cross-link the cross-linking agent having a high cross-linking temperature. Thus, the adherend can be laminated on the resin layer B side.

[0080] Furthermore, a plurality of cross-linking agents having different weight average molecular weights and equivalent weights of each reactive group may be used in combination.

[0081] As such a cross-linking agent, a cross-linking agent that can react with a carboxyl group is preferably a cross-linking agent containing an oxazoline group, a carbodiimide group, an isocyanate group, an epoxy group, an amino group, an organic metal salt, etc. Wherein, preferably there is an oxazoline group and / or a carbodiimide group. Thus, compared with the situation of adopting a cross-linking agent with an isocyanate group, an epoxy group, an amino group, an organic metal salt, etc., the coating property is better.

[0082] In the resin layer B, the content of the crosslinking agent is preferably 1.0 parts by weight or more, more preferably 2.5 parts by weight or more, and further preferably 4.0 parts by weight or more, relative to a total of 100 parts by weight of one or more selected from the group consisting of carboxyl-modified styrene-butadiene copolymer, carboxyl-modified acrylonitrile-styrene-butadiene copolymer, and carboxyl-modified methyl methacrylate-butadiene copolymer. In addition, it is preferably 80.0 parts by weight or less, more preferably 40.0 parts by weight or less, further preferably 30.0 parts by weight or less, and most preferably 20.0 parts by weight or less. In the case where the amount of the crosslinking agent contained is as small as less than 1.0 parts by weight, the interface strength with the resin layer A is reduced, thereby possibly reducing the tensile shear bonding strength, or causing an adverse effect on the coating properties.

[0083] On the other hand, when the amount of the crosslinking agent is more than 80.0 parts by weight, interfacial peeling may occur between the adherend B and the tensile shear adhesive strength may decrease.

[0084] (Oxazoline-containing cross-linking agent)

[0085] The oxazoline group-containing crosslinking agent is a compound having an oxazoline group, and among them, a polymer containing an oxazoline group is preferred. The polymer is obtained by homopolymerizing an addition-polymerizable oxazoline group-containing monomer or copolymerizing it with other monomers.

[0086] The oxazoline group-containing polymer is preferably an acrylic polymer which is a copolymer of an addition-polymerizable oxazoline group-containing monomer and a (meth)acryloyl group-containing monomer. The acrylic polymer in the oxazoline group-containing polymer may have a polyoxyalkylene chain.

[0087] As such a cross-linking agent containing oxazoline groups, as the monomer containing oxazoline groups of the addition polymerization, can be listed: 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline etc., can use one or two or more mixtures thereof. Among these, 2-isopropenyl-2-oxazoline is also easy to obtain industrially, is preferred. These addition polymerization monomers containing oxazoline groups can use only one, also can use two or more monomers.

[0088] As other monomers, any monomer that can be copolymerized with the addition polymerizable oxazoline group-containing monomer may be used. Examples of such monomers include: (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and its salts (the salts are sodium salts, potassium salts, ammonium salts, tertiary amine salts, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated amides such as acrylamides such as (meth)acrylamide, N-alkyl (meth)acrylamide, and N,N-dialkyl (meth)acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; α,β-unsaturated monomers containing halogen such as vinyl chloride, vinylidene chloride, and vinyl fluoride; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, etc.

[0089] As the alkyl group in these alkyl (meth)acrylates and unsaturated amides, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, and cyclohexyl may be used.

[0090] In addition, as other monomers, monomers having polyoxyalkylene chains can also be used. As monomers having polyoxyalkylene chains, for example, esters formed by adding polyoxyalkylene chains to hydrocarbon groups of unsaturated carboxylic acid esters such as (meth)acrylates are preferred. Here, polyoxyalkylene chains are preferably polyoxymethylene, polyoxyethylene, polyoxypropylene, and polyoxybutylene. The repeating units of the polyoxyalkylene chains are preferably in the range of 3 to 100, for example.

[0091] The other monomers used in the oxazoline compound may be used alone or in combination of two or more.

[0092] The amount of the oxazoline group of the oxazoline compound is preferably 0.5 to 10 mmol / g, more preferably 1 mmol / g or more, further preferably 3 mmol / g or more, and most preferably 4 mmol / g or more. In addition, it is more preferably 9 mmol / g or less, further preferably 8 mmol / g or less, and most preferably 6 mmol / g or less. By using it in the above range, it is easy to improve the durability of the coating film.

[0093] (Carbodiimide group-containing cross-linking agent)

[0094] The carbodiimide group-containing crosslinking agent is a compound having two or more carbodiimide groups. The polymer is obtained by homopolymerizing an addition-polymerizable carbodiimide group-containing monomer or copolymerizing it with other monomers.

[0095] The carbodiimide group-containing cross-linking agent preferably has a high weight average molecular weight, for example, preferably 1,000 or more, more preferably 2,000 or more, and further preferably 3,000 or more.

[0096] If the molecular weight of the carbodiimide group-containing crosslinking agent is too small, the hydrolysis resistance tends to decrease.

[0097] The carbodiimide equivalent of the carbodiimide group-containing cross-linking agent is preferably 50 or more, more preferably 100 or more, further preferably 200 or more, and most preferably 300 or more. In addition, it is preferably 800 or less, more preferably 700 or less, further preferably 600 or less, and most preferably 500 or less. The carbodiimide equivalent refers to the chemical formula weight per 1 mol of the carbodiimide group.

[0098] Within this range, the crosslinking agent shows good dispersibility in the composition for forming the resin layer B, especially in the aqueous dispersion containing the latex. Moreover, the drying film-forming temperature is set to 80°C or higher, and the reaction is not easy at a temperature below 80°C, and the reactivity can be reliably improved under the thermal bonding conditions (heating to 150-200°C). In addition, the pot life at a temperature around room temperature can be made into a sufficient period.

[0099] The crosslinking agent containing a carbodiimide group is obtained by a known method. As a known method, a diisocyanate compound is subjected to carbodiimidization in the presence of a known catalyst. In this case, a hydroxyl-containing compound can be reacted as an end-capping agent before, during, or after the carbodiimidization.

[0100] The diisocyanate compound as a raw material is not particularly limited, and the raw material is used to obtain a cross-linking agent containing a carbodiimide group by such a method. Examples of the diisocyanate compound include: chain aliphatic diisocyanate compounds such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate; aromatic diisocyanate compounds such as toluene diisocyanate, diphenylmethane diisocyanate, and 2,4,6-triisopropylbenzene-1,3-diisocyanate; and aliphatic diisocyanate compounds containing aromatic groups such as xylylene diisocyanate and 1,3-bis(2-isocyanato-2-propyl)benzene.

[0101] (Aqueous dispersion for forming resin layer B)

[0102] In the present invention, as the aqueous dispersion for forming the above-mentioned resin layer B, an aqueous dispersion containing the following latex and a cross-linking agent is used, wherein the latex is one or more selected from carboxyl-modified styrene-butadiene copolymer latex, carboxyl-modified acrylonitrile-styrene-butadiene copolymer latex and carboxyl-modified methyl methacrylate-butadiene copolymer latex.

[0103] In order to improve the coating property of the aqueous dispersion, an aqueous thickener may be added to the aqueous dispersion to adjust the viscosity as needed. As the aqueous thickener, an alkaline thickener, an associative thickener, or an aqueous thixotropic agent may be used to adjust the viscosity to a coating machine. For example, an aqueous thixotropic agent such as THIXOL K-1000 manufactured by Kyoeisha Chemical Co., Ltd., which is formed of a copolymer containing a carboxylic acid, may be used.

[0104] Furthermore, the minimum film-forming temperature of the aqueous dispersion for forming the resin layer B is preferably 30 to 99°C.

[0105] <Common matters between resin layer A and resin layer B>

[0106] (Additives, etc.)

[0107] The resin layer A and the resin layer B of the thermoplastic multilayer adhesive film of the present invention may independently contain near-infrared absorbing materials such as carbon black, graphene, graphite, diiminium salt, aminium salt, cyanine compound, phthalocyanine compound, dithiol metal complex, naphthoquinone compound, azo compound, talc, etc., as a result, they can be bonded by heating through irradiation with infrared rays such as laser.

[0108] The thermoplastic multilayer adhesive film of the present invention may contain inorganic fillers and nucleating agents such as talc, calcium carbonate, sepiolite, boehmite, bentonite, silica, titanium oxide, zinc oxide, glass beads, and metal fibers such as aluminum / nickel / copper in order to improve the rigidity and crystallization temperature of the film.

[0109] Organic anti-blocking agents such as acrylic beads may be used to prevent adhesion to the thermoplastic multilayer adhesive film of the present invention. Unlike inorganic anti-blocking agents, the use of organic anti-blocking agents does not increase the ash content.

[0110] The thermoplastic multilayer adhesive film may or may not contain a pigment or a conductive filler for the purpose of imparting conductivity.

[0111] In the thermoplastic multilayer adhesive film of the present invention, a tackifier may or may not be added, and may not be added when adhesion is not required. In addition, a plasticizer and other various cross-linking agents may or may not be added. Moreover, the resin layer A and the resin layer B are not foams, and do not contain a foaming agent for heating and foaming.

[0112] A resin film or the like having an easily removable surface may be attached to one or both sides of the thermoplastic multilayer adhesive film of the present invention before use. In this case, when in use, the resin film may be peeled off to expose the surface composed of the thermoplastic multilayer adhesive film of the present invention and then attached to the surface of an adherend.

[0113] In addition, in the thermoplastic multilayer adhesive film of the present invention, if the resin layer A is disposed on both sides of the resin layer A, the so-called intermediate layer may not be provided, or an arbitrary intermediate layer may be provided. In addition, it can also be used for the following purpose: the thermoplastic multilayer adhesive film of the present invention is laminated / bonded on both sides of the substrate sheet to form a total of five layers.

[0114] Furthermore, it is preferred that the resin layer A and the resin layer B of the thermoplastic multilayer adhesive film of the present invention are both continuous layers in the bonding region where bonding is intended. For example, the resin layer B is not formed only on a portion of one surface of the resin layer A. However, for example, when the resin layer B is configured to have a pattern such as dots or lines, the resin layer B melts and liquefies during heating and melting during thermal bonding, thereby forming a pattern configuration in which the entire layer is wet without omission, but the present invention is not limited to this.

[0115] In a part of the layers of the obtained laminate, a colorant is not intentionally contained to lose transparency. When a thermoplastic multilayer adhesive film in which resin layers B are laminated on both sides of a resin layer A is used as the thermoplastic multilayer adhesive film of the present invention, and when transparent amorphous resins as adherend B are laminated on the surfaces of the resin layer B respectively, the interface between the resin layer B and the adherend B can be made transparent.

[0116] (Manufacturing method)

[0117] As a method for producing the thermoplastic multilayer adhesive film of the present invention, first, the resin layer A can be obtained by a known method for obtaining a sheet-shaped molded product such as melt extrusion from a T-die, a circular die, etc., followed by cooling and solidification.

[0118] Next, in order to form a resin layer B on one side of the resin layer A, an aqueous dispersion is applied to one side of the resin layer A as a raw material of the resin layer B, which contains the following latex and a cross-linking agent, wherein the latex is one or more selected from carboxyl-modified styrene-butadiene copolymer latex, carboxyl-modified acrylonitrile-styrene-butadiene copolymer latex and carboxyl-modified methyl methacrylate-butadiene copolymer latex.

[0119] The coating method may be any known method capable of coating an aqueous dispersion, and any method such as a gravure roll coater, a rod coater, a die coater, a roll, a spray coater, a curtain coater, dipping, a brush coater, a knife coater, etc. may be used.

[0120] When the resin layer B is coated with an aqueous dispersion, the surface of the resin layer A may be subjected to corona discharge treatment, plasma discharge treatment, UV / ozone treatment, flame treatment, primer treatment, etc. in advance for the purpose of improving the surface wettability of the resin layer A.

[0121] When the resin layer B is formed on both sides of the resin layer A, the formation of the resin layer B on one side described above is also performed on the other side of the resin layer A.

[0122] After the resin layer B is formed by coating the surface of the resin layer A with the aqueous dispersion, the heating temperature for drying the coated layer needs to be a temperature at which the resin layer A does not soften.

[0123] For example, when the melting point of resin layer A is 110°C, the drying temperature of the layer formed from the aqueous dispersion for forming resin layer B is set to 80 to 85°C, and the drying time is set to about 2 to 4 minutes. When the melting point of resin layer A is 130°C, the drying temperature of the layer formed from the aqueous dispersion for forming resin layer B is set to 90 to 95°C, and the drying time is set to about 1 to 2 minutes.

[0124] It should be noted that, for the purpose of improving the surface wettability of at least one surface of the molded resin layer A and / or the surface of the resin layer B after formation, the surface of the thermoplastic multilayer adhesive film may be subjected to corona discharge treatment, plasma discharge treatment, UV / ozone treatment, flame treatment, etc.

[0125] (Bonding method)

[0126] Adherend A and adherend B are laminated on both surfaces of the thermoplastic multilayer adhesive film of the present invention, respectively, and heated by any method, thereby adhering adherend A and adherend B. At this time, the heating temperature is set to be higher than the reaction temperature of the crosslinking agent contained in the resin layer B. In this way, deformation of the adherend can be suppressed, and the carboxyl groups contained in the resin layer A and the resin layer B react with the crosslinking agent to form a crosslinked structure.

[0127] At this time, the temperatures of the adherends A and B during bonding can be lower than their melting points or softening points, and only the thermoplastic multilayer adhesive film can be melted while the adherends A and B are not melted or softened, thereby forming the above-mentioned cross-linked structure.

[0128] Furthermore, the adherend A or the adherend B layer may be formed by heating to a temperature higher than the melting point of at least one of the adherend A and the adherend B.

[0129] The bonding using the thermoplastic multilayer adhesive film of the present invention includes the following cases: the heating temperature condition during bonding is the case where both adherends are not melted and the case where at least one of the two adherends is melted. In the latter case, the following method can be used: overlapping the following adherend A on the surface of the resin layer A of the thermoplastic multilayer adhesive film, performing a heating and bonding process, and after the process, forming a layer formed by the heated and molten adherend B on the surface of the resin layer B of the thermoplastic multilayer adhesive film; overlapping the following adherend B on the surface of the resin layer B of the thermoplastic multilayer adhesive film, performing a heating and bonding process, and after the process, forming a layer formed by the heated and molten adherend A on the surface of the resin layer A of the thermoplastic multilayer adhesive film. At this time, the heated and molten adherend B and adherend A can be adherends formed by injection molding or casting molding on a single side of the thermoplastic multilayer adhesive film disposed in the molding die. In addition, it can also be an adherend formed by extrusion molding. It should be noted that, when the adherend A is metal, the following process is not performed: the metal is melted and supplied to one side of the thermoplastic multilayer adhesive film disposed in the molding die to form a layer. When the adherend A is metal, it is limited to the following method: the adherend A is overlapped on the surface of the resin layer A of the thermoplastic multilayer adhesive film, and the process of heating and bonding is performed, and after the process, a layer formed by the heated and melted adherend B is formed on the surface of the resin layer B of the thermoplastic multilayer adhesive film.

[0130] There is no limitation on the heating method during bonding, and any method can be used according to the characteristics of the adherend. For example, hot plate pressing, high-frequency dielectric heating bonding, resistance heating bonding, high-frequency induction heating bonding, infrared heating bonding, laser heating bonding, autoclave heating bonding, thermal lamination, ultrasonic heating bonding, vibration heating bonding, friction heating bonding, air hot pressing, pulse heating bonding, double belt press heating bonding, insert molding heating bonding, vacuum forming heating bonding, etc. can be used.

[0131] In this bonding process, the crosslinking agent present in the resin layer B crosslinks the resin constituting the resin layer B, further crosslinks the resin constituting the resin layer A, and crosslinks the resins constituting the resin layer A and the resin layer B with each other, thereby firmly bonding these layers.

[0132] It should be noted that, in the case of a thermoplastic multilayer adhesive film composed of three or more layers with resin layer A on both sides and resin layer B on the inner layer, or in the case of a thermoplastic multilayer adhesive film composed of three or more layers with resin layer B on both sides and resin layer A on the inner layer, adherend A and adherend B can be overlapped on both sides, respectively, and heated by the above-mentioned method for bonding. In addition, resin layer A itself can be a multilayer film with resin layer A on both sides, and resin layer B itself can be a multilayer film with resin layer B on both sides.

[0133] (Laminated body)

[0134] The laminate in the present invention is a laminate formed by bonding two adherends, an adherend A and an adherend B, via the thermoplastic multilayer adhesive film of the present invention. Adherend A and adherend B are respectively formed of the following materials as long as they are not deteriorated by conditions such as heating during bonding. In addition, it is preferred that the heating temperature during bonding is adjusted according to the materials so that adherend A and adherend B do not melt together during the bonding process.

[0135] The adherend A bonded to the resin layer A is formed by one or more materials selected from the following materials: steel plates such as galvanized steel plates; metals such as iron, aluminum, titanium, copper, zinc, tin, and magnesium alloys; non-metals such as pottery and ceramics; crystalline thermoplastic resins such as polypropylene resins, polyethylene resins, and polyamide resins; and thermosetting resins such as polyurethane resins, epoxy resins, and phenolic resins.

[0136] The adherend B bonded to the resin layer B is formed of one or more materials selected from the group consisting of ABS resin, polycarbonate resin, (meth)acrylic resin, polyvinyl chloride resin, and amorphous resins such as amorphous polyester resin.

[0137] The shapes of the adherend A and the adherend B can be independently selected from any shapes such as sheets, films, plates, rods, irregular shapes, fibers, fiber products, woven fabrics, and nonwoven fabrics.

[0138] The adherend A and the adherend B may each independently contain, in the case of a resin, a resin reinforced with carbon fiber or glass fiber, various colorants, extender pigments, plasticizers, and other known additives that may be contained in a resin composition.

[0139] The obtained laminate can be used in the following fields: automotive interior and exterior decoration parts, electrical appliances, housings of smartphones / tablet terminals / PCs, housings of home appliances, industrial equipment, daily necessities such as shoes and sandals, furniture, and other fields in which the materials of the above-mentioned adherends A and B have been used in the past.

[0140] The tensile shear adhesive strength of the laminate is preferably 4.5 MPa or more, more preferably 7.0 MPa or more, further preferably 10.0 MPa or more, and most preferably 12.0 MPa or more.

[0141] The higher the tensile shear bond strength, the stronger the bonded structure is maintained.

[0142] The 90-degree peel strength of the laminate is preferably 100 N / 25 mm or more, more preferably 150 N / 25 mm or more, further preferably 200 N / 25 mm or more, and most preferably 250 N / 25 mm or more.

[0143] The higher these tensile shear adhesive strength and 90-degree peel adhesive strength are, the stronger the bonded structure is maintained.

[0144] Example

[0145] Hereinafter, the present invention will be described in more detail with reference to Examples.

[0146] It should be noted that the embodiment is only one aspect of the invention, and the present invention is not limited thereto.

[0147] After fully kneading the materials according to the compounding components in Table 1 below (the properties of each component are described in Table 2), resin layers A1 to A7 (all 80 μm thick) were obtained by extrusion molding. Thereafter, the surface coated with the aqueous dispersion for forming the resin layer B was subjected to corona discharge treatment. For example, the resin layer A2 was formed from 20 parts by weight of maleic acid-modified polyethylene, 30 parts by weight of linear low-density polyethylene as other components, and 50 parts by weight of ethylene-1-hexene elastomer.

[0148] On the other hand, each component is fully stirred in a manner to become the compounding components shown in Table 3 (the characteristics of each component are recorded in Table 4), thereby obtaining an aqueous dispersion for forming resin layers B1 to B20. Table 3 records the compounding amount of latex and crosslinking agent including the solvent and the solid content amount excluding the solvent. In addition, the solid content weight parts of the crosslinking agent relative to 100 parts by weight of the copolymer solid content in the latex are recorded as the solid content ratio. Regarding B16 and B17, the weight of the polycarbodiimide solid content derived from the polycarbodiimide aqueous solution of the crosslinking agent as a whole is the same as the weight of the polycarbodiimide solid content derived from the polycarbodiimide aqueous dispersion.

[0149] As the cross-linking agent in Table 3 below, a polyvalent carbodiimide aqueous solution (concentration 40 wt% (CARBODILITE manufactured by Nisshinbo Chemical Co., Ltd.)), a polyvalent carbodiimide dispersion (concentration 40 wt% (CARBODILITE manufactured by Nisshinbo Chemical Co., Ltd.)), an oxazoline group-containing polymer aqueous solution (concentration 25 wt% (EPOCROS manufactured by Nippon Shokubai Co., Ltd.)), an oxazoline group-containing emulsion (concentration 40 wt% (EPOCROS manufactured by Nippon Shokubai Co., Ltd.)), a water-soluble epoxy resin aqueous solution (concentration 60 wt% (RIKABOND manufactured by Chuo Rika Kogyo Co., Ltd.)), an aqueous blocked isocyanate aqueous solution (concentration 25 wt% (MEIKANATE manufactured by Meisei Chemical Co., Ltd.)), and a titanium-based organic metal salt aqueous solution (concentration 44 wt% (ORGATIX manufactured by Matsumoto Fine Chemical Co., Ltd.) were used.

[0150] The resin layers A1 to A7 were adjusted to have a size of A4. On one side of each, an aqueous dispersion for forming the resin layers B1 to B20 was applied to form the thermoplastic multilayer adhesive films of Examples 1 to 26 and Comparative Examples 1 to 12 in Tables 6 to 8.

[0151] The A4-sized resin layers A1 to A7 were fixed on a glass plate with tape. The aqueous dispersion for forming the resin layers B1 to B20 was applied to the surfaces of the resin layers A1 to A7 using a Meyer bar (#16) to a thickness of 15 to 20 μm after drying.

[0152] The resin layers A1 to A7 coated with the aqueous dispersion for forming the resin layers B1 to B20 are placed in a dryer and heated and dried at 80 to 95° C. for 1 to 4 minutes.

[0153] The coating properties of the dried resin layers B1 to B20 were evaluated based on the following criteria.

[0154] ◎: Good.

[0155] ○: Slightly blurred and cracked.

[0156] △: There are large cracks.

[0157] ×: Stickiness, unevenness, and shrinkage cavities are present.

[0158] [Table 1]

[0159]

[0160] [Table 2]

[0161]

[0162] [Table 3]

[0163]

[0164] [Table 4]

[0165]

[0166] (Determination method of tensile shear bond strength)

[0167] The thermoplastic multilayer adhesive film and adherends A and B were bonded as described below so as to form the combinations shown in Tables 6 and 7 below, thereby obtaining respective laminates.

[0168] Each thermoplastic multilayer adhesive film of the embodiment and the comparative example was sandwiched between adherend A and adherend B. Then, heat bonding was performed using a hot plate press (CYPT-50 manufactured by Shinto Kogyo Co., Ltd.). At this time, adherend A was bonded to the surface on the resin layer A (a) side, and adherend B was bonded to the surface on the resin layer B (b) side.

[0169] It should be noted that, in adherends A and B, the test piece of 6-nylon with glass fiber added was 2.0 mm (thickness) × 20 mm (width) × 100 mm (length), the test piece of ABS resin was 3.0 mm (thickness) × 20 mm (width) × 75 mm (length), and the test piece of GA steel plate (galvanized-iron alloy) was 0.8 mm (thickness) × 20 mm (width) × 75 mm (length).

[0170] Each thermoplastic multilayer adhesive film used is 20 mm (width) × 10 mm (length), and the bonding area (200 mm 2 ) is based on bonding over the entire surface of the thermoplastic multilayer adhesive film.

[0171] Table 5-1 shows the thermal bonding conditions used to measure the tensile shear bond strength in the examples and comparative examples shown in Tables 6 and 7. In Table 5-1, for example, upper 235°C / lower 65°C means that the adherend A side is heated at 235°C and the adherend B side is heated at 65°C, and pressure 0.4 MPa means that the pressure applied to the adherends A and B and the thermoplastic multilayer adhesive films therebetween during thermal bonding is 0.4 MPa.

[0172] The tensile shear bond strength (MPa) of each laminated body was measured at 25° C. using a tensile elongation tester (Autograph: AGS-X manufactured by Shimadzu Corporation). The unbonded ends of adherend A and adherend B were clamped with a clamp, adherend A was fixed, and the clamp clamping adherend B was stretched in the longitudinal direction of adherend B at a tension rate of 100 mm / min.

[0173] During stretching, the strength at which cohesive failure of the bonded portion, failure of any adherend, or interfacial peeling occurred at the bonded portion was obtained, and this strength was divided by the bonded area to obtain the tensile shear bond strength (MPa).

[0174] [Table 5-1]

[0175]

[0176] (90 degree peel strength measurement method)

[0177] The thermoplastic multilayer adhesive film and adherends A and B were bonded as described below so as to form the combinations shown in Tables 6 and 7 below, thereby obtaining respective laminates.

[0178] Each thermoplastic multilayer adhesive film of the embodiment and the comparative example was sandwiched between adherend A and adherend B. Then, heat bonding was performed using a hot plate press (CYPT-50 manufactured by Shinto Kogyo Co., Ltd.). At this time, adherend A was bonded to the surface on the resin layer A (a) side, and adherend B was bonded to the surface on the resin layer B (b) side.

[0179] In the adherends A and B, the test piece of ABS resin was 3.0 mm (thickness)×25 mm (width)×130 mm (length), and the test piece of aluminum was 0.5 mm (thickness)×25 mm (width)×130 mm (length).

[0180] Each thermoplastic multilayer adhesive film used is 25 mm (width) × 80 mm (length), and the bonding area (2000 mm 2 ) is based on bonding on the entire surface of the thermoplastic multilayer adhesive film. At this time, each thermoplastic multilayer adhesive film is 50 mm shorter than the length of the adherend A and the adherend B, so after bonding, the ends of the adherend A and the adherend B extend from each thermoplastic multilayer adhesive film.

[0181] Table 5-2 shows the thermal bonding conditions used to measure the 90-degree peel strength in the examples and comparative examples shown in Table 8. In Table 5-2, for example, upper 185°C / lower 50°C means that the adherend A (0.5 mm thick aluminum plate) side is heated at 185°C and the adherend B (3 mm thick ABS resin) side is heated at 50°C, and pressure 1.0 MPa means that the pressure applied to the adherends A and B and the thermoplastic multilayer adhesive films therebetween during thermal bonding is 1.0 MPa.

[0182] For each laminated body produced, the 90-degree peel strength (N / 25mm) was measured at 25°C using a high-strength elongation tester (Autograph: AGS-X manufactured by Shimadzu Corporation). The unbonded end of the adherend A was bent upward by 90 degrees, and the end was clamped by the upper clamp of the Autograph. While the bent portion was kept at 90 degrees, the upper clamp was lifted at a speed of 100mm / min, and the strength at the time of cohesive failure at the bonding site, failure of any adherend, or interfacial peeling at the bonding site was taken as the 90-degree peel strength (N / 25mm).

[0183] [Table 5-2]

[0184]

[0185] [Table 6]

[0186]

[0187] [Table 7]

[0188]

[0189] [Table 8]

[0190]

[0191] According to the examples described in Tables 6 and 7, in order to achieve a sufficiently strong tensile shear bonding strength, 6-nylon with glass fiber added can be bonded to ABS resin, and GA steel plate can be bonded to ABS resin. For example, the results of measuring the tensile shear bonding strength showed that according to Examples 4 and 8, interfacial peeling at the interface between the resin layer A or B and any adherend and cohesive failure in the resin layer A and / or the resin layer B coexisted. Moreover, when the tensile shear bonding strength exceeded 12.0 MPa, cohesive failure mainly occurred.

[0192] In contrast, when bonding was performed by only one of the resin layers as in Comparative Examples 1, 2, 7, and 8, the tensile shear bonding strength was extremely low. In addition, in Comparative Example 9, in which the resin used in the resin layer A was not the resin of the present invention, sufficient tensile shear bonding strength could not be obtained. In addition, according to Comparative Example 3, in which the resin layer B did not contain a crosslinking agent, and Comparative Examples 4 to 6, in which the resin layer B containing a resin other than the resin of the present invention was used, the coating property when the resin layer B was provided was poor and sufficient tensile shear bonding strength could not be obtained. In addition, according to Comparative Example 10, in which the layer was obtained only from a polycarbodiimide aqueous solution, sufficient tensile shear bonding strength could not be obtained.

[0193] Generally, the linear expansion coefficients of the combination of metal and resin are greatly different, so the adherends after thermal bonding are easily peeled off. According to Examples 21 to 26 as examples of the present invention recorded in Table 8, even in such a case of bonding an aluminum plate to an ABS resin, a high bonding strength is obtained. In particular, according to Examples 22 and 23 using a crosslinking agent obtained by mixing a polycarbodiimide aqueous solution and a polycarbodiimide aqueous dispersion, a stronger 90-degree peel bonding strength is achieved compared to Examples 21 and 23 to 26 using only one of them.

[0194] Similarly, according to Comparative Examples 11 and 12 obtained only from the polyvalent carbodiimide aqueous solution and only from the polyvalent carbodiimide aqueous dispersion, sufficient 90-degree peel strength could not be obtained.

Claims

1. A thermoplastic multilayer adhesive film, wherein: It has the following resin layer A and the following resin layer B, Resin layer A: a layer containing carboxylic acid-modified polyolefin and / or ionomer, Resin layer B: a layer containing a polymer and a crosslinking agent, wherein the polymer is at least one selected from a carboxyl-modified styrene-butadiene copolymer, a carboxyl-modified acrylonitrile-styrene-butadiene copolymer, and a carboxyl-modified methyl methacrylate-butadiene copolymer.

2. The thermoplastic multilayer adhesive film according to claim 1, wherein: The crosslinking agent contained in the resin layer B is a crosslinking agent containing an oxazoline group or a carbodiimide group.

3. The thermoplastic multilayer adhesive film according to claim 1 or 2, wherein: In the resin layer A, the total content of the carboxylic acid-modified polyolefin and the ionomer is 8.0% by weight or more.

4. The thermoplastic multilayer adhesive film according to claim 1 or 2, wherein: In the resin layer B, the content of the crosslinking agent is 1.0 to 80.0 parts by weight based on 100 parts by weight of a total of one or more selected from the group consisting of carboxyl-modified styrene-butadiene copolymers, carboxyl-modified acrylonitrile-styrene-butadiene copolymers, and carboxyl-modified methyl methacrylate-butadiene copolymers.

5. A laminated body, which is formed by heat-bonding the following adherend A to the surface of the resin layer A of the thermoplastic multilayer adhesive film according to claim 1 or 2, and heat-bonding the following adherend B to the surface of the resin layer B, respectively, Adherend A: at least one selected from metal, polypropylene resin, polyethylene resin, polyamide resin and thermosetting resin, Adherend B: at least one selected from ABS resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin and amorphous polyester resin.

6. A bonding method, wherein: The following adherend A is overlapped on the surface of the resin layer A of the thermoplastic multilayer adhesive film according to claim 1 or 2, and the following adherend B is overlapped on the surface of the resin layer B, and the resin layer A and the resin layer B are heated and melted to perform thermal bonding, Adherend A: at least one selected from metal, polypropylene resin, polyethylene resin, polyamide resin and thermosetting resin, Adherend B: at least one selected from ABS resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin and amorphous polyester resin.

7. A method comprising: A step of overlapping the adherend A described below on the surface of the resin layer A of the thermoplastic multilayer adhesive film according to claim 1 or 2, heating and bonding, and after this step, a step of forming a layer composed of the adherend B described below melted by heating on the surface of the resin layer B of the thermoplastic multilayer adhesive film, or, The method comprises: a step of overlapping the following adherend B on the surface of the resin layer B of the thermoplastic multilayer adhesive film according to claim 1 or 2, heating and bonding, and after this step, a step of forming a layer formed of the following adherend A melted by heating on the surface of the resin layer A of the thermoplastic multilayer adhesive film, Adherend A: at least one selected from metal, polypropylene resin, polyethylene resin, polyamide resin and thermosetting resin, Adherend B: at least one selected from ABS resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin and amorphous polyester resin.

8. A method for producing a thermoplastic multilayer adhesive film, wherein: On a resin layer A composed of a layer containing a carboxylic acid-modified polyolefin or ionomer and subjected to surface treatment as needed, an aqueous composition containing the following latex and a cross-linking agent is applied, and the water is dried at a temperature at which the resin layer A does not soften or melt to form a resin layer B. The latex is one or more selected from carboxyl-modified styrene-butadiene copolymer latex, carboxyl-modified acrylonitrile-styrene-butadiene copolymer latex and carboxyl-modified methyl methacrylate-butadiene copolymer latex.

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