Adhesive for high frequency dielectric heating, structure and method for manufacturing the structure

Abstract

The present invention provides an adhesive for high-frequency dielectric heating, which contains a thermoplastic resin (A), wherein the thermoplastic resin (A) contains a styrene copolymer resin (a1), wherein the content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is 40% by volume or more and 100% by volume or less, and the content of the styrene monomer unit in the styrene copolymer resin (a1) is 10% by mass or more and 90% by mass or less, and the tensile elastic modulus of the adhesive for high-frequency dielectric heating is 20 MPa or more, and the dielectric properties (tanδ / ε'r) of the adhesive for high-frequency dielectric heating are 0.005 or more. (tanδ is the dielectric loss tangent at 23°C and a frequency of 40.68 MHz, and ε'r is the relative dielectric constant at 23°C and a frequency of 40.68 MHz).

Description

Technical Field

[0001] The present invention relates to an adhesive for high-frequency dielectric heating, a structure, and a method for manufacturing the structure. Background Art

[0002] As a method of bonding a plurality of adherends to produce a laminate, for example, a method of sandwiching an adhesive between adherends and performing dielectric heating, induction heating, ultrasonic welding, or laser welding has been proposed.

[0003] For example, Patent Document 1 discloses that a resin blend of a polyolefin resin and a styrene copolymer resin is thermally melt bonded to a surface sheet having a film layer containing silicon dioxide. Furthermore, the film layer described in Patent Document 1 comprises, relative to 100 parts by mass of the polyolefin resin, a resin blend containing 50 parts by mass of the styrene copolymer resin and 5 parts by mass of silicon dioxide.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-148839 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In the top sheet disclosed in Patent Document 1, the content of the styrene copolymer resin in the resin blend contained in the film layer is small. Therefore, for example, when the top sheet disclosed in Patent Document 1 is joined to an adherend containing a styrene resin, it is difficult to join the top sheet and the adherend in a short time, and the adhesion of the top sheet to the adherend is insufficient.

[0009] In addition, existing adhesives containing styrene-based resins still have room for further improvement in strength properties such as fracture toughness.

[0010] The object of the present invention is to provide a high-frequency dielectric heating adhesive containing a styrene resin that can achieve short-time bonding and has improved fracture toughness, as well as a structure bonded to an adherend using the high-frequency dielectric heating adhesive and a method for manufacturing the structure.

[0011] Solution to the problem

[0012] According to one embodiment of the present invention, there is provided an adhesive for high-frequency dielectric heating, wherein the adhesive for high-frequency dielectric heating contains a thermoplastic resin (A), the thermoplastic resin (A) contains a styrene copolymer resin (a1), the content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is greater than 40% by volume and less than 100% by volume, the content of the styrene monomer unit in the styrene copolymer resin (a1) is greater than 10% by mass and less than 90% by mass, the tensile elastic modulus of the adhesive for high-frequency dielectric heating is greater than 20 MPa, and the dielectric properties (tanδ / ε'r) of the adhesive for high-frequency dielectric heating are greater than 0.005.

[0013] (tanδ is the dielectric loss tangent at 23°C and a frequency of 40.68MHz,

[0014] ε'r is the relative dielectric constant at 23°C and a frequency of 40.68 MHz.)

[0015] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the adhesive for high-frequency dielectric heating further include a dielectric filler (B) that generates heat when a high-frequency electric field is applied.

[0016] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the dielectric filler (B) is at least one selected from the group consisting of zinc oxide, silicon carbide, titanium oxide, and barium titanate.

[0017] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, it is preferred that the flow start temperature of the high-frequency dielectric heating adhesive be 80° C. or higher and 250° C. or lower.

[0018] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, the styrene-based copolymer resin (a1) is preferably a styrene-based elastomer.

[0019] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, the styrene-based copolymer resin (a1) is preferably a hydrogenated resin.

[0020] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the thermoplastic resin (A) further contains a thermoplastic resin (a2) different from the styrene-based copolymer resin (a1).

[0021] In the high-frequency dielectric heating adhesive of one embodiment of the present invention, the content of the styrene-based copolymer resin (a1) is preferably 20% by volume or more and 98% by volume or less based on the entire high-frequency dielectric heating adhesive.

[0022] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, it is preferable that the high-frequency dielectric heating adhesive is used while a high-frequency electric field of 3 MHz to 300 MHz is applied.

[0023] In the high-frequency dielectric heating adhesive of one embodiment of the present invention, the high-frequency dielectric heating adhesive is preferably an adhesive for joining one or more adherends, and at least one of the one or more adherends contains a resin having an aromatic ring.

[0024] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, the resin having an aromatic ring is preferably a styrene-based resin.

[0025] In the adhesive for high-frequency dielectric heating according to one aspect of the present invention, it is preferable that the adhesive for high-frequency dielectric heating is an adhesive sheet.

[0026] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, it is preferred that the adhesive sheet have a thickness of 5 μm or more and 2000 μm or less.

[0027] According to one aspect of the present invention, there is provided a structure in which one or more adherends are joined by the adhesive for high-frequency dielectric heating according to one aspect of the present invention.

[0028] According to one embodiment of the present invention, a method for manufacturing a structure can be provided, the method comprising: a process of configuring a high-frequency dielectric heating adhesive of one embodiment of the present invention on one or more adherends; and a process of applying a high-frequency electric field of greater than 3 MHz and less than 300 MHz to the high-frequency dielectric heating adhesive to join the adherends.

[0029] According to one embodiment of the present invention, there can be provided a high-frequency dielectric heating adhesive containing a styrene-based resin that can achieve short-time bonding and has improved fracture toughness, as well as a structure to which an adherend is bonded by the high-frequency dielectric heating adhesive and a method for manufacturing the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A This is a schematic cross-sectional view showing an example of the adhesive for high-frequency dielectric heating according to the present embodiment.

[0031] Figure 1B This is a schematic cross-sectional view showing another example of the adhesive for high-frequency dielectric heating according to the present embodiment.

[0032] Figure 1C This is a schematic cross-sectional view showing another example of the adhesive for high-frequency dielectric heating according to the present embodiment.

[0033] Figure 2 This is a schematic cross-sectional view showing an example of a structure according to the present embodiment.

[0034] Figure 3 This is a schematic cross-sectional view showing another example of the structure of this embodiment.

[0035] Figure 4 This is a schematic diagram for explaining an example of a high-frequency dielectric heating process using the high-frequency dielectric heating adhesive and the dielectric heating device according to the present embodiment.

[0036] Explanation of symbols

[0037] 10, 20...adhesive layer, 11...first surface, 21...second surface, 30...substrate, 40...intermediate layer, 100, 200...structure, 1A, 1B, 1C...adhesive for high-frequency dielectric heating, 50...dielectric heating device, 51...first high-frequency electric field applying electrode, 52...second high-frequency electric field applying electrode, 53...high-frequency power source, 110, 210...first adherend, 120, 220...second adherend DETAILED DESCRIPTION

[0038] [Adhesive for high frequency dielectric heating]

[0039] The high-frequency dielectric heating adhesive of the present embodiment contains a thermoplastic resin (A). The thermoplastic resin (A) contains a styrene copolymer resin (a1). The content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is greater than 40% by volume and less than 100% by volume. The content of the styrene monomer unit in the styrene copolymer resin (a1) is greater than 10% by mass and less than 90% by mass. In addition, the tensile modulus of the high-frequency dielectric heating adhesive of the present embodiment is greater than 20 MPa. In addition, the dielectric properties (tanδ / ε'r) of the high-frequency dielectric heating adhesive of the present embodiment are greater than 0.005.

[0040] (tanδ is the dielectric loss tangent at 23°C and a frequency of 40.68MHz,

[0041] ε'r is the relative dielectric constant at 23°C and a frequency of 40.68 MHz.)

[0042] <Thermoplastic resin (A)>

[0043] The thermoplastic resin (A) includes a styrene copolymer resin (a1). The thermoplastic resin (A) may include a thermoplastic resin (a2) different from the styrene copolymer resin (a1), or may not include the thermoplastic resin (a2). The thermoplastic resin (a2) will be described later.

[0044] (Styrene copolymer resin (a1))

[0045] In the high-frequency dielectric heating adhesive of the present embodiment, the content of the styrene copolymer resin (a1) relative to the entire thermoplastic resin (A) is 40% by volume or more and 100% by volume or less on a volume basis.

[0046] When the content of the styrene copolymer resin (a1) relative to the total thermoplastic resin (A) is 40 volume % or more, for example, when the high-frequency dielectric heating adhesive is joined to an adherend containing a resin having an aromatic ring, it is easy to improve the adhesion between the adherend and the high-frequency dielectric heating adhesive of this embodiment.

[0047] The content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is preferably 45% by volume or more, more preferably 50% by volume or more, further preferably 55% by volume or more, and still further preferably 60% by volume or more, based on volume.

[0048] The upper limit of the content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is not particularly limited, and for example, on a volume basis, it may be less than 100% by volume, 95% by volume or less, 92% by volume or less, or 90% by volume or less.

[0049] When the content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is 45% by volume or more, for example, when the thermoplastic resin (A) is bonded to an adherend containing a resin having an aromatic ring, the adhesiveness to the adherend is likely to be further improved.

[0050] The content of the styrene copolymer resin (a1) is preferably 20% by volume or more, more preferably 30% by volume or more, further preferably 40% by volume or more, and further preferably 50% by volume or more, based on the volume of the entire high-frequency dielectric heating adhesive.

[0051] The content of the styrene-based copolymer resin (a1) is preferably 98% by volume or less, more preferably 95% by volume or less, based on the volume of the entire high-frequency dielectric heating adhesive.

[0052] When the content of the styrene copolymer resin (a1) is 20% by volume or more based on the total high-frequency dielectric heating adhesive, for example, when bonding to an adherend containing a resin having an aromatic ring, the adhesion to the adherend is easily further improved.

[0053] When the content of the styrene copolymer resin (a1) is 98% by volume or less based on the total volume of the high-frequency dielectric heating adhesive, the dielectric properties of the high-frequency dielectric heating adhesive are easily improved, and the adhesiveness to the adherend is easily improved.

[0054] In the high-frequency dielectric heating adhesive of the present embodiment, the amount of the styrene-based monomer units contained in the styrene-based copolymer resin (a1) is 10% by mass or more and 90% by mass or less on a mass basis.

[0055] When the content of the styrene monomer unit in the styrene copolymer resin (a1) is 10% by mass or more, for example, the adhesiveness of the high-frequency dielectric heating adhesive to an adherend containing a resin having an aromatic ring can be easily improved, and the heat resistance in the assumed actual use environment can also be easily improved.

[0056] When the content of styrene monomer units in the styrene copolymer resin (a1) is less than 90 mass%, it is easy to improve the fracture toughness of the high-frequency dielectric heating adhesive. Therefore, for example, when the high-frequency dielectric heating adhesive of this embodiment is used to join adherends and an impact is applied to the structure, it is easy to prevent the structure from being destroyed.

[0057] The content of the styrene monomer unit in the styrene copolymer resin (a1) is preferably 15% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, further preferably 30% by mass or more, further preferably 40% by mass or more, further preferably 50% by mass or more, based on mass.

[0058] The content of the styrene monomer unit in the styrene copolymer resin (a1) is preferably 80% by mass or less, more preferably 70% by mass or less, based on mass.

[0059] When the content of the styrene monomer unit in the styrene copolymer resin (a1) is 15% by mass or more, for example, when the resin is bonded to an adherend containing a resin having an aromatic ring, the adhesiveness to the adherend can be more easily improved.

[0060] When the content of the styrene-based monomer unit in the styrene-based copolymer resin (a1) is 80% by mass or less, it is easier to improve the fracture toughness of the adhesive for high-frequency dielectric heating.

[0061] Here, in this specification, the styrene copolymer resin refers to a resin obtained by copolymerizing a styrene monomer and other monomers. That is, the styrene copolymer resin includes a styrene monomer unit and other monomer units different from the styrene monomer unit. The styrene monomer refers to a monomer having a styrene skeleton.

[0062] In the present specification, a styrene-based resin is a resin having a styrene skeleton, and refers to at least one of a styrene-based homopolymer resin (a homopolymer containing a styrene-based monomer unit) and a styrene-based copolymer resin (a copolymer containing a styrene-based monomer unit).

[0063] Examples of the styrene copolymer resin (a1) include resins obtained by copolymerizing a styrene monomer such as α-methylstyrene or β-methylstyrene with an aliphatic monomer (a monomer having an aliphatic compound skeleton). The styrene copolymer resin may be a hydrogenated styrene resin (hydrogenated resin) obtained by hydrogenating a copolymer resin of a styrene monomer and an aliphatic monomer.

[0064] The styrene-based copolymer resin (a1) is preferably a styrene-based elastomer.

[0065] In the present specification, the styrene-based copolymer resin (a1) includes a styrene-based elastomer.

[0066] When styrene copolymer resin (a1) is styrene elastomer, it is easy to further improve the fracture toughness of high-frequency dielectric heating adhesive. As styrene elastomer, styrene-conjugated diene copolymer and styrene-olefin copolymer etc. can be cited. As a specific example of styrene-conjugated diene copolymer, it can be listed: unhydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene / butylene-styrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer (SIS), styrene-ethylene / isoprene-styrene copolymer; hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene / propylene-styrene copolymer (SEPS) and styrene-ethylene / butylene-styrene copolymer (SEBS) etc. Styrene elastomer can be a hydrogenated substance (hydrogenated resin) or an unhydrogenated substance.

[0067] The styrene copolymer resin (a1) is preferably a hydrogenated resin, more preferably a hydrogenated resin of a styrene elastomer. When the styrene copolymer resin (a1) is a hydrogenated resin, it is not easy to be reduced due to ozone degradation, and it is easy to improve the weather resistance of the adhesive for high-frequency dielectric heating. By improving weather resistance, for example, the decrease in fracture toughness over time is suppressed.

[0068] The styrene copolymer resin (a1) may be used alone or in combination of two or more. For example, it may be at least one selected from styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), and styrene-ethylene / butylene-styrene copolymer (SEBS). Among them, the styrene copolymer resin (a1) preferably includes styrene-ethylene / butylene-styrene copolymer (SEBS).

[0069] (Thermoplastic resin (a2))

[0070] The thermoplastic resin (a2) is a component that can be contained in the thermoplastic resin (A) as needed. The content of the thermoplastic resin (a2) in the thermoplastic resin (A) is 0 volume % or more and 60 volume % or less on a volume basis.

[0071] When the thermoplastic resin (A) contains the thermoplastic resin (a2), the content of the thermoplastic resin (a2) in the thermoplastic resin (A) is preferably more than 0 volume %, more preferably 5 volume % or more, further preferably 8 volume % or more, and further preferably 10 volume % or more on a volume basis.

[0072] When the thermoplastic resin (A) contains the thermoplastic resin (a2), the content of the thermoplastic resin (a2) in the thermoplastic resin (A) is preferably 55% by volume or less, more preferably 50% by volume or less, further preferably 45% by volume or less, and even more preferably 40% by volume or less, based on volume.

[0073] When the content of the thermoplastic resin (a2) exceeds 0% by volume, heat resistance is easily imparted to the adhesive for high-frequency dielectric heating.

[0074] When the content of the thermoplastic resin (a2) is 55% by volume or less, the content of the styrene copolymer resin (a1) in the thermoplastic resin (A) increases, so that, for example, when joining to an adherend containing a resin having an aromatic ring, it is easier to improve the adhesion to the adherend.

[0075] The type of the thermoplastic resin (a2) is not particularly limited. When the thermoplastic resin (a2) is a resin different from the styrene copolymer resin (a1), one type may be used alone or two or more types may be used in combination.

[0076] As described above, the thermoplastic resin (a2) is a resin different from the styrene copolymer resin (a1). Therefore, in the present embodiment, the styrene copolymer resin (a1) is not included in the styrene resin as the thermoplastic resin (a2). Hereinafter, in the description of the thermoplastic resin (a2), the styrene resin as the thermoplastic resin (a2) is sometimes referred to as a styrene resin (a3) ​​for convenience.

[0077] For example, from the viewpoint of easy melting and heat resistance, the thermoplastic resin (a2) is preferably at least one selected from polyolefin resins, polyolefin resins having polar parts, styrene resins (a3), polyacetal resins, polycarbonate resins, polyacrylic resins, polyamide resins, polyimide resins, polyvinyl acetate resins, phenoxy resins, polyester resins, polyphenylene sulfide resins and polyphenylene ether resins.

[0078] Among the resins exemplified above, the thermoplastic resin (a2) is more preferably a polyolefin resin or a polyphenylene ether resin, and is further preferably a polyolefin resin. When the thermoplastic resin (a2) is a polyolefin resin or a polyphenylene ether resin, the compatibility with the styrene copolymer resin (a1) increases, and it is easy to obtain a high bonding strength. In addition, when the thermoplastic resin (a2) is a polyolefin resin, the high-frequency dielectric heating adhesive is easily melted when a high-frequency electric field is applied, so it is easy to obtain a high bonding strength.

[0079] In this specification, polyolefin resins include polyolefin resins having polar sites and polyolefin resins having no polar sites. When the presence or absence of polar sites is specified, it is described as polyolefin resins having polar sites or polyolefin resins having no polar sites.

[0080] The thermoplastic resin (a2) is preferably a polyolefin resin having a polar part. The thermoplastic resin (a2) may be a polyolefin resin having no polar part.

[0081] Polyolefin resin

[0082] Examples of polyolefin resins as thermoplastic resins (a2) include resins formed from homopolymers such as polyethylene, polypropylene, polybutene and polymethylpentene, and α-olefin resins formed from copolymers of monomers selected from ethylene, propylene, butene, hexene, octene and 4-methylpentene. The polyolefin resins as thermoplastic resins (a2) may be a single resin or a combination of two or more resins.

[0083] ·Polyolefin resins with polar parts

[0084] The polar part in the polyolefin resin having a polar part is not particularly limited as long as it can impart polarity to the polyolefin resin. The polyolefin resin having a polar part is preferred because it exhibits high adhesion to the adherend. In addition, by making the adhesive for high-frequency dielectric heating contain a polyolefin resin having a polar part as the thermoplastic resin (a2), it is easy to improve the dielectric properties and increase the adhesion to the adherend, which is preferred.

[0085] The polyolefin thermoplastic resin having a polar part may be a copolymer of an olefin monomer and a monomer having a polar part. In addition, the polyolefin thermoplastic resin having a polar part may be a resin obtained by introducing a polar part into a polyolefin resin obtained by polymerization of an olefin monomer by modification such as addition reaction.

[0086] There is no particular restriction on the type of olefin monomer constituting the polyolefin resin having a polar part. Examples of the olefin monomer include ethylene, propylene, butene, hexene, octene and 4-methyl-1-pentene. The olefin monomer may be used alone or in combination of two or more.

[0087] The olefin monomer is preferably ethylene or propylene from the viewpoint of excellent mechanical strength and stable adhesive properties.

[0088] The structural unit derived from olefin in the polyolefin-based resin having a polar part is preferably a structural unit derived from ethylene or propylene.

[0089] Examples of the polar site include a hydroxyl group, a carboxyl group, a vinyl acetate structure, and an acid anhydride structure, etc. Examples of the polar site include an acid-modified structure introduced into a polyolefin-based resin by acid modification, etc.

[0090] The acid-modified structure as a polar part is a part introduced by acid-modifying a thermoplastic resin (e.g., a polyolefin resin). As the compound used when acid-modifying a polyolefin resin, an unsaturated carboxylic acid derivative component derived from any one of an unsaturated carboxylic acid, an anhydride of an unsaturated carboxylic acid, and an ester of an unsaturated carboxylic acid can be cited. In this specification, a polyolefin resin having an acid-modified structure is sometimes referred to as an acid-modified polyolefin resin.

[0091] Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0092] Examples of the anhydride of unsaturated carboxylic acid include anhydrides of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, and citraconic anhydride.

[0093] Examples of the esters of unsaturated carboxylic acids include esters of unsaturated carboxylic acids such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl itaconate, diethyl itaconate, dimethyl citrate, diethyl citrate and dimethyl tetrahydrophthalate.

[0094] Styrene resin (a3)

[0095] The styrene resin (a3) ​​as the thermoplastic resin (a2) may be a homopolymer of a styrene monomer (polystyrene: PS), and examples thereof include a homopolymer of styrene, a homopolymer of α-methylstyrene, and a homopolymer of β-methylstyrene.

[0096] PS may be a general-purpose polystyrene resin (GPPS resin) or a high-impact polystyrene resin (HIPS resin). The high-impact polystyrene resin (HIPS resin) is a resin containing a GPPS resin and a rubbery elastomer.

[0097] Polyphenylene ether resin

[0098] The polyphenylene ether resin as the thermoplastic resin (a2) may be, for example, a homopolymer resin of polyphenylene ether or a copolymer resin of polyphenylene ether. Alternatively, it may be a polymer alloy of a polyphenylene ether resin and a resin other than the polyphenylene ether resin, that is, a modified polyphenylene ether resin.

[0099] <Dielectric filler (B)>

[0100] The adhesive for high-frequency dielectric heating of the present embodiment may contain the dielectric filler (B), or may not contain the dielectric filler (B) as long as target dielectric properties can be obtained.

[0101] The dielectric filler (B) is a filler that generates heat when a high-frequency electric field is applied. The high-frequency electric field is an electric field whose direction is reversed at a high frequency.

[0102] The dielectric filler (B) is preferably a filler that generates heat when a high-frequency electric field in the frequency range of 3 MHz to 300 MHz is applied. The dielectric filler (B) is preferably a filler that generates heat when a high-frequency electric field in the frequency range of 3 MHz to 300 MHz is applied, for example, a frequency of 13.56 MHz, 27.12 MHz or 40.68 MHz.

[0103] The dielectric filler (B) is preferably zinc oxide, silicon carbide (SiC), anatase titanium oxide, barium titanate, barium zirconate titanate, lead titanate, potassium niobate, rutile titanium oxide, hydrated aluminum silicate, hydrated aluminum silicate of alkali metals and other inorganic materials having water of crystallization, or hydrated aluminum silicate of alkaline earth metals and other inorganic materials having water of crystallization, etc., alone or in combination of two or more thereof.

[0104] The dielectric filler (B) is preferably at least one selected from zinc oxide, silicon carbide, barium titanate, and titanium oxide, and more preferably at least one selected from zinc oxide, barium titanate, and titanium oxide.

[0105] Among the dielectric fillers exemplified, the dielectric filler (B) is further preferably zinc oxide in terms of the rich variety, various shapes and sizes that can be selected, and the ability to improve the bonding properties and mechanical properties of the high-frequency dielectric heating adhesive in accordance with the purpose. By using zinc oxide as the dielectric filler (B), a colorless high-frequency dielectric heating adhesive can be obtained. Among dielectric fillers, the density of zinc oxide is small. Therefore, when the adherend is joined using a high-frequency dielectric heating adhesive containing zinc oxide as a dielectric filler (B), the total weight of the joint is not easy to increase compared to the case where an adhesive containing other dielectric fillers is used. Among ceramics, the hardness of zinc oxide is not too high, so it is not easy to damage the manufacturing device of the high-frequency dielectric heating adhesive. Since zinc oxide is an inactive oxide, even if it is combined with a thermoplastic resin, the damage to the thermoplastic resin is small.

[0106] The titanium oxide as the dielectric filler (B) is preferably at least one of anatase titanium oxide and rutile titanium oxide, and is more preferably anatase titanium oxide from the viewpoint of excellent dielectric properties.

[0107] The volume content of the dielectric filler (B) in the adhesive for high-frequency dielectric heating is preferably 5 volume % or more, more preferably 8 volume % or more, and even more preferably 10 volume % or more.

[0108] The volume content of the dielectric filler (B) in the adhesive for high-frequency dielectric heating is preferably 50 volume % or less, more preferably 40 volume % or less, further preferably 35 volume % or less, and further preferably 25 volume % or less.

[0109] When the volume content of the dielectric filler (B) in the high-frequency dielectric heating adhesive is 5 volume % or more, the heat generation property is improved, and the high-frequency dielectric heating adhesive and the adherend are easily firmly bonded.

[0110] By making the volume content of the dielectric filler (B) in the high-frequency dielectric heating adhesive 50% or less by volume, it is possible to prevent the strength of the adhesive from being reduced, and as a result, it is possible to prevent the reduction in bonding strength by using the adhesive. In addition, when the high-frequency dielectric heating adhesive of the present embodiment is an adhesive sheet, by making the volume content of the dielectric filler (B) in the adhesive sheet 50% or less by volume, it is easy to obtain flexibility as a sheet and it is also easy to prevent the reduction in toughness, so that it is easy to process the high-frequency dielectric heating adhesive sheet into a desired shape in a later process.

[0111] It should be noted that, when the adhesive for high-frequency dielectric heating of the present embodiment contains a thermoplastic resin (A) and a dielectric filler (B), the volume content of the dielectric filler (B) is preferably 5% by volume or more, more preferably 8% by volume or more, and further preferably 10% by volume or more relative to the total volume of the thermoplastic resin (A) and the dielectric filler (B). The volume content of the dielectric filler (B) is preferably 50% by volume or less, more preferably 40% by volume or less, further preferably 35% by volume or less, and further preferably 25% by volume or less relative to the total volume of the thermoplastic resin (A) and the dielectric filler (B).

[0112] The volume average particle size of the dielectric filler (B) is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more.

[0113] The volume average particle size of the dielectric filler (B) is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less.

[0114] When the volume average particle size of the dielectric filler (B) is 1 μm or more, the adhesive for high-frequency dielectric heating exhibits high heat generation performance when a high-frequency electric field is applied, and the adhesive layer and the adherend can be firmly bonded in a short time.

[0115] By making the volume average particle size of the dielectric filler (B) less than 30 μm, the high-frequency dielectric heating adhesive exhibits high heat generation performance when a high-frequency electric field is applied, and the adhesive layer and the adherend can be firmly bonded in a short time. In addition, when the high-frequency dielectric heating adhesive of this embodiment is an adhesive sheet, by making the volume average particle size of the dielectric filler (B) less than 30 μm, the strength of the high-frequency dielectric heating adhesive sheet can be prevented from decreasing.

[0116] The volume average particle size of the dielectric filler (B) is measured by the following method: The particle size distribution of the dielectric filler (B) is measured by a laser diffraction / scattering method, and the volume average particle size is calculated based on the results of the particle size distribution measurement in accordance with JIS Z 8819-2:2001.

[0117] <Additives>

[0118] The adhesive for high-frequency dielectric heating of the present embodiment may contain additives or may not contain additives.

[0119] When the high-frequency dielectric heating adhesive of the present embodiment includes additives, the additives include, for example, tackifiers, plasticizers, waxes, colorants, antioxidants, ultraviolet absorbers, antibacterial agents, coupling agents, viscosity modifiers, organic fillers, and inorganic fillers, etc. The organic fillers and inorganic fillers as additives are different from the dielectric fillers.

[0120] Thickeners and plasticizers can improve the melting characteristics and adhesive characteristics of adhesives for high-frequency dielectric heating.

[0121] Examples of the tackifier include rosin derivatives, polyterpene resins, aromatic modified terpene resins, hydrogenated aromatic modified terpene resins, terpene phenol resins, coumarone-indene resins, aliphatic petroleum resins, aromatic petroleum resins, and hydrogenated aromatic petroleum resins.

[0122] As plasticizers, for example, petroleum-based process oils, natural oils, dibasic acid dialkyl esters, and low molecular weight liquid polymers can be cited. As petroleum-based process oils, for example, paraffin-based process oils, cycloparaffin-based process oils, and aromatic-based process oils can be cited. As natural oils, for example, castor oil and tall oil can be cited. As dibasic acid dialkyl esters, for example, dibutyl phthalate, dioctyl phthalate, and dibutyl adipate can be cited. As low molecular weight liquid polymers, for example, liquid polybutene and liquid polyisoprene can be cited.

[0123] When the high-frequency dielectric heating adhesive of the present embodiment contains an additive, the content of the additive in the high-frequency dielectric heating adhesive is usually preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more, based on the total amount of the high-frequency dielectric heating adhesive. In addition, the content of the additive in the high-frequency dielectric heating adhesive is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less.

[0124] The high-frequency dielectric heating adhesive of the present embodiment preferably does not contain a solvent. The high-frequency dielectric heating adhesive that does not contain a solvent is less likely to cause a VOC (Volatile Organic Compounds) problem caused by the adhesive used for bonding to an adherend.

[0125] The high-frequency dielectric heating adhesive of the present embodiment preferably does not contain carbon or carbon compounds with carbon as the main component (for example, carbon black, etc.) and conductive substances such as metals. The high-frequency dielectric heating adhesive of the present embodiment preferably does not contain, for example, carbon steel, α iron, γ iron, δ iron, copper, iron oxide, brass, aluminum, iron-nickel alloy, iron-nickel-chromium alloy, carbon fiber and carbon black.

[0126] In the case where the high-frequency dielectric heating adhesive of the present embodiment contains a conductive substance, the content of the conductive substance in the adhesive is preferably 7 mass % or less, more preferably 6 mass % or less, further preferably 5 mass % or less, further preferably 1 mass % or less, further preferably 0.1 mass % or less, each independently based on the total amount of the adhesive.

[0127] The content of the conductive substance in the adhesive is particularly preferably 0 mass %.

[0128] When the content of the conductive substance in the adhesive is 7% by mass or less, it is easy to prevent the problem of carbonization of the bonding portion and the adherend due to electrical insulation breakdown during dielectric heating treatment.

[0129] In the adhesive for high-frequency dielectric heating of this embodiment, the total content of the thermoplastic resin (A) and the dielectric filler (B) is preferably 80 mass % or more, more preferably 90 mass % or more, further preferably 93 mass % or more, further preferably 95 mass % or more, further preferably 99 mass % or more.

[0130] <Characteristics of adhesives for high-frequency dielectric heating>

[0131] Next, the characteristics of the high-frequency dielectric heating adhesive according to the present embodiment will be described.

[0132] (Tensile elastic modulus)

[0133] The tensile modulus of the high-frequency dielectric heating adhesive of the present embodiment will be described. The tensile modulus of the high-frequency dielectric heating adhesive of the present embodiment is 20 MPa or more.

[0134] When the tensile elastic modulus of the high-frequency dielectric heating adhesive is less than 20 MPa, the high-frequency dielectric heating adhesive is easily damaged when an impact is applied to the structure when the high-frequency dielectric heating adhesive is joined to the adherend. In addition, the high-frequency dielectric heating adhesive has low operability and low processability when joining the high-frequency dielectric heating adhesive to the adherend.

[0135] The upper limit of the tensile modulus of the high-frequency dielectric heating adhesive is not particularly limited, and may be, for example, 2000 MPa or less. If the tensile modulus of the high-frequency dielectric heating adhesive is too high, for example, the processability may be reduced when the high-frequency dielectric heating adhesive is cut into a given size in advance.

[0136] The tensile elastic modulus of the high-frequency dielectric heating adhesive of the present embodiment is preferably 50 MPa or more, more preferably 100 MPa or more, further preferably 200 MPa or more, further preferably 500 MPa or more, further preferably 750 MPa or more, further preferably 1000 MPa or more.

[0137] The tensile elastic modulus of the high-frequency dielectric heating adhesive of the present embodiment is preferably 1900 MPa or less, more preferably 1800 MPa or less, and even more preferably 1500 MPa or less.

[0138] If the tensile modulus of the high-frequency dielectric heating adhesive is 50 MPa or more, it is easier to suppress the destruction of the high-frequency dielectric heating adhesive even if an impact is applied to the structure when the high-frequency dielectric heating adhesive is joined to the adherend. In addition, the high-frequency dielectric heating adhesive has higher operability and processability when joining the high-frequency dielectric heating adhesive to the adherend.

[0139] When the tensile elastic modulus of the high-frequency dielectric heating adhesive is 1900 MPa or less, the processability is higher when a structure obtained by bonding the high-frequency dielectric heating adhesive to an adherend is cut into a predetermined size in advance.

[0140] (Tensile elongation at break)

[0141] In the adhesive for high-frequency dielectric heating of the present embodiment, the tensile elongation at break is preferably 5% or more, more preferably 10% or more, and even more preferably 20% or more.

[0142] In the high-frequency dielectric heating adhesive of this embodiment, the tensile elongation at break is preferably 1500% or less, more preferably 1000% or less, further preferably 750% or less, further preferably 500% or less, further preferably 200% or less, further preferably 100% or less.

[0143] If the tensile elongation at break of the high-frequency dielectric heating adhesive is 5% or more, the high-frequency dielectric heating adhesive is not easily damaged even if an impact is applied to the structure when the high-frequency dielectric heating adhesive is joined to the adherend. In addition, the high-frequency dielectric heating adhesive has high operability when joining the high-frequency dielectric heating adhesive to the adherend. It is easy to process.

[0144] When the tensile elongation at break is 1500% or less, processing is facilitated when the adhesive for high-frequency dielectric heating is cut into a given size in advance.

[0145] In this specification, the tensile modulus of the adhesive for high-frequency dielectric heating can be measured in accordance with JIS K 7161-1:2014 and JIS K 7127:1999.

[0146] In addition, in this specification, the tensile elongation at break of the adhesive for high-frequency dielectric heating can be measured in accordance with JIS K7161-1:2014 and JIS K 7127:1999.

[0147] (Dielectric properties)

[0148] The dielectric property (tan δ / ε'r) of the high-frequency dielectric heating adhesive of the present embodiment will be described. The dielectric property (tan δ / ε'r) of the high-frequency dielectric heating adhesive of the present embodiment is 0.005 or more.

[0149] (tanδ is the dielectric loss tangent at 23°C and a frequency of 40.68MHz,

[0150] ε'r is the relative dielectric constant at 23°C and a frequency of 40.68 MHz.)

[0151] When the dielectric property of the high-frequency dielectric heating adhesive is 0.005 or more, the high-frequency dielectric heating adhesive easily generates heat during dielectric heating treatment, and the high-frequency dielectric heating adhesive and the adherend can be firmly bonded in a short time.

[0152] The dielectric property of the adhesive for high-frequency dielectric heating of the present embodiment is more preferably 0.008 or more, and further preferably 0.010 or more.

[0153] When the dielectric property of the high-frequency dielectric heating adhesive of the present embodiment is 0.008 or more, the high-frequency dielectric heating adhesive generates heat more easily during dielectric heating treatment, and the high-frequency dielectric heating adhesive and the adherend can be firmly bonded in a short time.

[0154] The upper limit of the dielectric properties of the high-frequency dielectric heating adhesive of the present embodiment is not particularly limited. The dielectric properties of the high-frequency dielectric heating adhesive of the present embodiment may be, for example, less than 0.1, less than 0.08, or less than 0.05. The dielectric properties of the high-frequency dielectric heating adhesive may, for example, satisfy a range of greater than 0.005 and less than 0.1.

[0155] When the dielectric property of the adhesive for high-frequency dielectric heating is 0.1 or less, overheating can be easily suppressed, and damage to the portion where the adherend and the adhesive for high-frequency dielectric heating are in contact is less likely to occur.

[0156] The dielectric property (tan δ / ε'r) is a value obtained by dividing the dielectric loss tangent (tan δ) measured using an impedance material device or the like by the relative dielectric constant (ε'r) measured using an impedance material device or the like.

[0157] The dielectric loss tangent (tan δ) and relative dielectric constant (ε′r), which are dielectric properties of the adhesive for high-frequency dielectric heating, can be measured simply and accurately using an impedance material analyzer.

[0158] It should be noted that the details of the method for measuring the dielectric properties of the adhesive for high-frequency dielectric heating and the adherend are as follows. First, a measuring sheet of the adhesive for high-frequency dielectric heating is obtained. When it is necessary to obtain a measuring sheet from a structure, a measuring sheet of uniform thickness is obtained by cutting or cutting from the structure. In the case where a sheet is not formed, for example, in a granular state, a measuring sheet is obtained by forming a sheet using a hot press or the like. The thickness of the measuring sheet is, for example, greater than 10 μm and less than 2 mm. For the sheet obtained in this way, the relative dielectric constant (ε'r) and the dielectric loss tangent (tanδ) are respectively measured at a frequency of 40.68 MHz at 23°C using an RF impedance / material analyzer E4991A (manufactured by Agilent), and the values ​​of the dielectric properties (tanδ / ε'r) are calculated.

[0159] (Flow start temperature)

[0160] In the high-frequency dielectric heating adhesive of the present embodiment, the flow start temperature is preferably 80° C. or higher, more preferably 100° C. or higher, further preferably 120° C. or higher, and further preferably 140° C. or higher.

[0161] In the high-frequency dielectric heating adhesive of the present embodiment, the flow start temperature is preferably 250° C. or lower, more preferably 220° C. or lower, further preferably 200° C. or lower, and further preferably 180° C. or lower.

[0162] When the flow start temperature of the adhesive for high-frequency dielectric heating is 80° C. or higher, a structure produced using the adhesive for high-frequency dielectric heating can easily obtain heat resistance in daily life.

[0163] When the flow start temperature of the high-frequency dielectric heating adhesive is 250° C. or less, it is easy to prevent the time required to melt the high-frequency dielectric heating adhesive from being prolonged during bonding, and it is also easy to obtain the bonding strength between the high-frequency dielectric heating adhesive and the adherend.

[0164] The flow start temperature can be measured by the method described in the section of Examples described later.

[0165] <Method of adhesive for high frequency dielectric heating>

[0166] The shape of the high-frequency dielectric heating adhesive of the present embodiment is not particularly limited, and is preferably in the form of a sheet. That is, the high-frequency dielectric heating adhesive of the present embodiment is preferably an adhesive sheet (sometimes referred to as a high-frequency dielectric heating adhesive sheet). By making the high-frequency dielectric heating adhesive an adhesive sheet, the time of the manufacturing process of the structure can be further shortened.

[0167] In one embodiment, the high-frequency dielectric heating adhesive of the present embodiment is composed of only one adhesive layer, and the adhesive layer is formed by the high-frequency dielectric heating adhesive sheet of the present embodiment. In the case where the high-frequency dielectric heating adhesive is a high-frequency dielectric heating adhesive sheet formed by only one adhesive layer, the adhesive layer itself is equivalent to the high-frequency dielectric heating adhesive sheet, and therefore, the morphology and characteristics of the high-frequency dielectric heating adhesive sheet are equivalent to the morphology and characteristics of the adhesive layer. The high-frequency dielectric heating adhesive sheet is preferably formed by only a single adhesive layer. The high-frequency dielectric heating adhesive of the present embodiment is preferably a high-frequency dielectric heating adhesive sheet formed by only a single adhesive layer. As a result, the thickness of the high-frequency dielectric heating adhesive sheet can be thinned, and the high-frequency dielectric heating adhesive sheet can be simply molded.

[0168] The high-frequency dielectric heating adhesive of this embodiment is not limited to the high-frequency dielectric heating adhesive sheet formed by only one adhesive layer. In other forms of high-frequency dielectric heating adhesive, it is sometimes a high-frequency dielectric heating adhesive sheet composed of multiple layers. In this case, a method in which layers other than the adhesive layer are stacked can also be cited.

[0169] The adhesive sheet for high-frequency dielectric heating is sometimes formed of only one adhesive layer having high-frequency dielectric heating adhesiveness. Therefore, in this specification, the terms "adhesive sheet for high-frequency dielectric heating" and "adhesive layer" can be used interchangeably depending on the situation.

[0170] Figure 1A , Figure 1B and Figure 1C The schematic diagrams illustrate a plurality of aspects of the high-frequency dielectric heating adhesive according to the present embodiment.

[0171] Figure 1A The illustrated high-frequency dielectric heating adhesive 1A is an adhesive sheet composed of only a single adhesive layer 10 .

[0172] Figure 1B The adhesive 1B for high-frequency dielectric heating shown is an adhesive sheet having an adhesive layer 10 and a substrate 30 supporting the adhesive layer 10. The adhesive layer 10 has a first surface 11. The substrate 30 is not particularly limited as long as it is a component that can support the adhesive layer 10. The substrate 30 can be, for example, a resin sheet containing at least one resin selected from polyolefin resins, polyester resins, acetate resins, ABS resins, polystyrene resins, and vinyl chloride resins. As polyolefin resins, polyethylene resins, polypropylene resins, etc. can be cited. As polyester resins, polybutylene terephthalate resins, polyethylene terephthalate resins, etc. can be cited. The substrate 30 may contain a dielectric filler (B). The dielectric filler (B) in the adhesive layer 10 and the dielectric filler in the substrate 30 are the same or different from each other.

[0173] Figure 1C The high-frequency dielectric heating adhesive 1C shown is an adhesive sheet having an intermediate layer 40 arranged between an adhesive layer 10 and an adhesive layer 20. The high-frequency dielectric heating adhesive 1C has a first surface 11 and a second surface 21 on the opposite side of the first surface 11. In the high-frequency dielectric heating adhesive 1C, the adhesive layer 10 only needs to satisfy the conditions of the adhesive layer of the high-frequency dielectric heating adhesive sheet of the present embodiment. In one embodiment, the adhesive layer 10 and the adhesive layer 20 are layers of the same composition and properties. In one embodiment, the adhesive layer 20 is a layer of high-frequency dielectric heating adhesive that is different from the adhesive layer 10 in at least any aspect of the composition and properties. In one embodiment, the adhesive layer 20 is a layer of a general adhesive, which is not a layer of high-frequency dielectric heating adhesive. In this case, the non-high frequency dielectric heating adhesive layer 20 may be, for example, a layer of a drying-curing adhesive that dries and cures by evaporation of water or a solvent, or a layer of an adhesive made of an adhesive (pressure-sensitive adhesive).

[0174] (thickness)

[0175] When the high-frequency dielectric heating adhesive of this embodiment is an adhesive sheet formed by only one adhesive layer, the thickness of the adhesive sheet of this embodiment is preferably 5 μm or more, more preferably 10 μm or more, further preferably 30 μm or more, and particularly preferably 50 μm or more.

[0176] When the thickness of the adhesive sheet is 5 μm or more, the heat generation when high frequency is applied to the adhesive sheet in contact with the adherend is improved, so it is easy to firmly bond the adhesive sheet and the adherend in a short time. In addition, when bonding with the adherend, the adhesive sheet easily follows the unevenness of the adherend and is easy to show bonding strength.

[0177] When the adhesive sheet has a multilayer structure composed of a plurality of layers, the thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, further preferably 30 μm or more, and further preferably 50 μm or more.

[0178] When the adhesive sheet for high-frequency dielectric heating is a multilayer sheet, if the thickness of the adhesive layer is 5 μm or more, the adhesive layer easily follows the irregularities of the adherend during bonding to the adherend, and the adhesive strength is easily exhibited.

[0179] The upper limit of the thickness of the adhesive sheet is not particularly limited. The thicker the thickness of the adhesive sheet, the higher the weight of the overall structure obtained by bonding the adhesive sheet and the adherend. Therefore, the adhesive sheet is preferably a thickness in a range that is not problematic in practical use, such as processability and operability. Also considering the practicality and formability of the adhesive sheet for high-frequency dielectric heating, the thickness of the adhesive sheet of the present embodiment is preferably less than 2000 μm, more preferably less than 1000 μm, and further preferably less than 600 μm. Whether it is a structure formed by only one layer of adhesive layer or any case of a multilayer structure formed by multiple layers including an adhesive layer, the upper limit of the thickness of the preferred adhesive sheet is the above value.

[0180] Compared with the case of using a liquid adhesive that needs to be applied, the adhesive sheet as an adhesive for high-frequency dielectric heating is easy to handle and has high workability when joining to an adherend.

[0181] In addition, the thickness of the adhesive sheet used as the adhesive for high-frequency dielectric heating can be appropriately controlled. Therefore, the adhesive sheet can also be applied to the roll-to-roll method, and the adhesive sheet can be processed into any area and shape according to the bonding area with the adherend and the shape of the adherend by punching, etc. Therefore, from the perspective of the manufacturing process, the advantages of the adhesive sheet used as the adhesive for high-frequency dielectric heating are also significant.

[0182] The high-frequency dielectric heating adhesive of the present embodiment is preferably used by applying a high-frequency electric field in the so-called short-wave to ultra-short-wave frequency band (for example, above 3 MHz and below 300 MHz). When a high-frequency electric field in this frequency band is applied, the heating depth is deep, and therefore, the heat generation property is improved when high frequency is applied. Therefore, even when the thickness of the high-frequency dielectric heating adhesive is thick, it is easy to firmly bond the adhesive sheet and the adherend in a short time. The high-frequency dielectric heating adhesive of the present embodiment is preferably used for bonding with one or more adherends. The adherend will be described later.

[0183] As an index of the fracture toughness of the adhesive for high-frequency dielectric heating according to the present embodiment, for example, right-angle tear strength can be cited.

[0184] In the adhesive for high-frequency dielectric heating of this embodiment, the right-angle tear strength is preferably 15 N / mm or more, more preferably 20 N / mm or more, further preferably 25 N / mm or more, further preferably 30 N / mm or more, further preferably 40 N / mm or more, further preferably 50 N / mm or more.

[0185] When the right-angle tear strength of the high-frequency dielectric heating adhesive of this embodiment is 15 N / mm or more, for example, even if a strong impact is applied to a structure obtained by bonding the high-frequency dielectric heating adhesive and an adherend, destruction of the structure is easily suppressed.

[0186] The upper limit of the right-angle tear strength of the adhesive for high-frequency dielectric heating of the present embodiment is not particularly limited, and may be, for example, 200 N / mm or less, or 100 N / mm or less.

[0187] <Method for producing adhesive for high-frequency dielectric heating>

[0188] The high-frequency dielectric heating adhesive of the present embodiment can be manufactured, for example, by mixing the above-mentioned components. In the case where the high-frequency dielectric heating adhesive of the present embodiment is an adhesive sheet, for example, the above-mentioned components can be premixed, kneaded using a known kneading device such as an extruder and a hot roll, and manufactured using a known molding method such as extrusion molding, calendering molding, injection molding, and cast molding.

[0189] [Adherent]

[0190] The material of the adherend is not particularly limited and may be any of an organic material and an inorganic material (including a metal material, etc.), or may be a composite material of an organic material and an inorganic material.

[0191] The material of the adherend is preferably an organic material. As the organic material of the material of the adherend, for example, plastic materials and rubber materials can be cited. As plastic materials, for example: polypropylene resin, polyethylene resin, epoxy resin, polyurethane resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polycarbonate resin (PC resin), polyamide resin (nylon 6 and nylon 66, etc.), polyester resin (polyethylene terephthalate (PET resin) and polybutylene terephthalate resin (PBT resin)), polyacetal resin (POM resin), polymethyl methacrylate resin, and styrene resin (polystyrene resin, etc.), etc. As rubber materials, styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPR), and silicone rubber, etc. can be cited. In addition, the adherend can be a foaming material of an organic material.

[0192] The inorganic material of the material of the adherend can be glass material, cement material, ceramic material, and metal material. In addition, the adherend can be a composite material of fiber and the above-mentioned plastic material, that is, fiber reinforced plastics (FRP). The plastic material in the fiber reinforced resin is, for example, selected from polypropylene resin, polyethylene resin, polyurethane resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polycarbonate resin (PC resin), polyamide resin (nylon 6 and nylon 66, etc.), polyester resin (polyethylene terephthalate (PET resin) and polybutylene terephthalate resin (PBT resin)), polyacetal resin (POM resin), polymethyl methacrylate resin, and polystyrene resin. The fiber in the fiber reinforced resin can be, for example, glass fiber, Kevlar fiber, and carbon fiber.

[0193] The conductivity of the adherend is preferably low.

[0194] When one or more adherends are joined using the high-frequency dielectric heating adhesive of the present embodiment, the one or more adherends are made of the same material or different materials. Among the one or more adherends, the material of at least one adherend preferably contains a thermoplastic resin as a main body. In this specification, "containing as a main body" means that the object substance contains the most relative to the whole. For example, it means that the content ratio of the object substance is 50% by mass or more as a proportion of the whole.

[0195] In the case where the material of at least one of more than one adherends includes a thermoplastic resin as the main body, it is preferred that at least one adherend includes a resin having an aromatic ring. The resin having an aromatic ring is a resin containing an aromatic ring in the molecule, and examples thereof include: aromatic polyester resins (e.g., polyethylene terephthalate (PET resin)), aromatic polycarbonate resins (aromatic PC resins), polyphenylene sulfide resins (PPS resins), polyphenylene ether resins (PPE resins), and styrene resins (e.g., polystyrene resins), etc. Among them, the resin having an aromatic ring is preferably a styrene resin. That is, the material of the adherend is preferably a styrene resin, and more preferably a styrene resin as the main body. When the adherend includes a styrene resin, the adhesion when joined with the high-frequency dielectric heating adhesive of the present embodiment is excellent. In the case where more than two adherends are joined, the more than two adherends may include the same resin with an aromatic ring, or may include different resins with an aromatic ring. For example, more than two adherends may both include styrene resins. In the case where two or more adherends both contain styrene resins, the two or more adherends may contain the same styrene resins as each other, or may contain different styrene resins. The styrene resin used as the material of the adherend may include the same resins as those described in the above-mentioned styrene copolymer resin (a1) and thermoplastic resin (a2). Among the exemplified resins, a homopolymer of a styrene monomer (polystyrene: PS) is preferably included. Relative to the entire thermoplastic resin contained in the adherend, on a mass basis, the adherend more preferably contains 50% by mass or more of a resin having an aromatic ring, further preferably contains 60% by mass or more, further preferably contains 70% by mass or more, and particularly preferably contains 80% by mass or more. When the material of the adherend includes a styrene resin, an aromatic polyester resin, an aromatic polycarbonate resin, a polyphenylene sulfide resin, or a polyphenylene ether resin, the adherend preferably contains 50% by mass or more of the resin, more preferably 60% by mass or more, further preferably 70% by mass or more, and further preferably 80% by mass or more, based on mass, relative to the entire thermoplastic resin contained in the adherend.

[0196] The shape of the adherend is not particularly limited. In the case where the high-frequency dielectric heating adhesive of the present embodiment is an adhesive sheet, the adherend preferably has a surface that can be bonded to the adhesive sheet, preferably in the form of a sheet or a plate. In the case where a plurality of adherends are bonded to each other, the shapes and sizes of these adherends may be the same or different.

[0197] [Structure]

[0198] The structure of the present embodiment includes the high-frequency dielectric heating adhesive of the present embodiment, and one or more adherends. In the structure of the present embodiment, one or more adherends are joined by the high-frequency dielectric heating adhesive of the present embodiment. The structure of the present embodiment is preferably a structure (for example, a laminate) formed by stacking more than one adherend sandwiched by the high-frequency dielectric heating adhesive. In addition, the structure of the present embodiment can be a structure formed by stacking more than two adherends sandwiched by the high-frequency dielectric heating adhesive. Below, the situation in which the structure of the present embodiment has two adherends is described with reference to the accompanying drawings.

[0199] Figure 2 Schematic cross-sectional view of a structure 100 as an example of this embodiment is shown in FIG.

[0200] The structure 100 includes a first adherend 110 and a second adherend 120, and an adhesive 1A for high-frequency dielectric heating, and the adhesive 1A for high-frequency dielectric heating is arranged between the first adherend 110 and the second adherend 120. The structure 100 is a laminated body in which the first adherend 110, the adhesive 1A for high-frequency dielectric heating, and the second adherend 120 are laminated in sequence. The first adherend 110 and the second adherend 120 have the same dimensions in the thickness direction and the same dimensions in the length direction. In the structure 100, the first adherend 110, the adhesive 1A for high-frequency dielectric heating, and the second adherend 120 are arranged at positions where the central portions in the length direction of each are aligned.

[0201] Figure 3 Schematic cross-sectional view of a structure 200 as another example of the present embodiment is shown in FIG.

[0202] The structure 200 includes a first adherend 210 and a second adherend 220, and a high-frequency dielectric heating adhesive 1A, and the high-frequency dielectric heating adhesive 1A is arranged between the first adherend 210 and the second adherend 220. The structure 200 is a laminated body in which the first adherend 210, the high-frequency dielectric heating adhesive 1A, and the second adherend 220 are laminated in sequence. The first adherend 210 and the high-frequency dielectric heating adhesive 1A have the same size in the length direction. The size in the thickness direction and the size in the length direction of the second adherend 220 are larger than the size of the first adherend 210. The first adherend 110 and the high-frequency dielectric heating adhesive 1A are arranged at a position where both ends in the length direction are aligned. The first adherend 110, the high-frequency dielectric heating adhesive 1A, and the second adherend 220 are arranged at a position where one end in each length direction is aligned.

[0203] In the case where the structure of the present embodiment is a laminate, the material of the adherend in the laminate is preferably an organic material. In the case where the laminate has more than two adherends, the adherends may be made of the same material or different materials. For more than two adherends in the laminate, it is preferred that the material of at least one adherend contains a thermoplastic resin as a main body. Thermoplastic resins used as the material of the adherend may be resins having aromatic rings (for example, styrene resins) and the like. The resins having aromatic rings used as the material of the adherend may include the resins exemplified above. In addition, the styrene resins used as the material of the adherend may include the same resins as those described in the above-mentioned styrene copolymer resin (a1) and thermoplastic resin (a2). For example, in Figure 2 In the case of the structure 100, the materials of the first adherend 110 and the second adherend 120 as the outermost layers are preferably organic materials. In the case where the materials of the first adherend 110 and the second adherend 120 are organic materials, at least one of the first adherend 110 and the second adherend 120 preferably contains a resin having an aromatic ring (for example, a styrene-based resin). Figure 3 The same applies to the first adherend 210 and the second adherend 220 in the structure 200 .

[0204] In the structure of this embodiment, the arrangement position and thickness of the high-frequency dielectric heating adhesive are not limited to Figure 2 and Figure 3 The position and thickness shown.

[0205] In the structure of this embodiment, the shape, size, and number of the adherends are not limited to Figure 2 and Figure 3 The shapes, sizes and quantities shown.

[0206] The structure of this embodiment is not limited to Figure 2 and Figure 3 The structure is formed by laminating two adherends as shown in the figure with an adhesive for high-frequency dielectric heating interposed therebetween.

[0207] [Method for manufacturing structure]

[0208] The method for manufacturing a structure of the present embodiment includes: a process of configuring the high-frequency dielectric heating adhesive of the present embodiment on one or more adherends; and a process of applying a high-frequency electric field to the high-frequency dielectric heating adhesive to join one or more adherends. The frequency of the applied high-frequency electric field is, for example, greater than 3 MHz and less than 300 MHz. In the case of joining two or more adherends and the high-frequency dielectric heating adhesive of the present embodiment to manufacture a structure, the method for manufacturing a structure of the present embodiment includes: a process of configuring the high-frequency dielectric heating adhesive of the present embodiment between two or more adherends; and a process of applying a high-frequency electric field to the high-frequency dielectric heating adhesive to join two or more adherends. In this case, the frequency of the applied high-frequency electric field is, for example, also greater than 3 MHz and less than 300 MHz.

[0209] In the method for manufacturing a structure of the present embodiment, preferably, two or more adherends and a high-frequency dielectric heating adhesive are arranged between the electrodes of the dielectric heating device, and the two or more adherends and the high-frequency dielectric heating adhesive are pressurized by the electrodes and a high-frequency electric field is applied. By applying pressure and a high-frequency electric field by the electrodes, it is easy to manufacture the structure in a shorter time.

[0210] According to the manufacturing method of the high-frequency dielectric heating adhesive using the present embodiment, only a predetermined portion can be locally heated from the outside by a dielectric heating device. Therefore, even when the adherend is a large and complex three-dimensional structure or a thick and complex three-dimensional structure, and high dimensional accuracy is required, the manufacturing method of the high-frequency dielectric heating adhesive using the present embodiment is effective.

[0211] Hereinafter, as an example of a method for producing a structured body according to the present embodiment, a method of bonding two or more adherends using the adhesive for high-frequency dielectric heating according to the present embodiment will be described, but the present invention is not limited to this method.

[0212] The bonding method according to one aspect of the present embodiment includes the following steps P1 and P2.

[0213] Process P1

[0214] Step P1 is a step of arranging the high-frequency dielectric heating adhesive of the present embodiment between two or more adherends. When manufacturing a laminated body as a structure of the present embodiment, in step P1, for example, the adherends and the high-frequency dielectric heating adhesive are alternately arranged, and two or more adherends are laminated with the high-frequency dielectric heating adhesive sandwiched therebetween.

[0215] The high-frequency dielectric heating adhesive is preferably sandwiched between the adherends in a manner that allows the adherends to be joined to each other. The high-frequency dielectric heating adhesive may be sandwiched between a portion of the adherends, between multiple locations between the adherends, or between the entire surface of the adherends. From the perspective of increasing the bonding strength between the adherends, the high-frequency dielectric heating adhesive is preferably sandwiched between the entire joining surfaces of the adherends.

[0216] In addition, as a method of sandwiching the high-frequency dielectric heating adhesive between a portion of the adherends, a method of arranging the high-frequency dielectric heating adhesive in a frame shape along the periphery of the bonding surface between the adherends and sandwiching the high-frequency dielectric heating adhesive between the adherends can be cited. By arranging the high-frequency dielectric heating adhesive in a frame shape, the bonding strength between the adherends can be obtained, and the structure can be made lighter than when the high-frequency dielectric heating adhesive is arranged on the entire bonding surface.

[0217] In addition, according to a method of sandwiching a portion of the high-frequency dielectric heating adhesive between the adherends, the amount of high-frequency dielectric heating adhesive used can be reduced and the size can be reduced. Therefore, compared with the case where the high-frequency dielectric heating adhesive is arranged on the entire joint surface, the high-frequency dielectric heating treatment time can be shortened.

[0218] Process P2

[0219] Step P2 is a step of applying a high-frequency electric field to the high-frequency dielectric heating adhesive disposed between the adherends in step P1 to join two or more adherends. In one embodiment, the frequency of the applied high-frequency electric field is greater than 3 MHz and less than 300 MHz. For example, a high-frequency electric field can be applied to the high-frequency dielectric heating adhesive by using a dielectric heating device.

[0220] (Dielectric Heating Device)

[0221] Figure 4 Schematic diagrams for explaining high-frequency dielectric heating treatment using the high-frequency dielectric heating adhesive and the dielectric heating device according to the present embodiment are shown in FIG.

[0222] Figure 4 The dielectric heating device 50 shown includes a first high-frequency electric field applying electrode 51 , a second high-frequency electric field applying electrode 52 , and a high-frequency power source 53 .

[0223] The first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 are arranged opposite to each other. The first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 have a pressurizing mechanism. By using the pressurizing mechanism of the electrodes (the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52) of the dielectric heating device 50, it is also possible to pressurize and apply a high-frequency electric field to two or more adherends and the high-frequency dielectric heating adhesive arranged between the electrodes.

[0224] Figure 4 The structure 100 is manufactured using a dielectric heating device 50 (see Figure 2 The dielectric heating device 50 can be used to apply pressure to the first adherend 110, the high-frequency dielectric heating adhesive 1A, and the second adherend 120 between the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52.

[0225] When a pair of plate electrodes, in which the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 are parallel to each other, is configured, such an electrode arrangement may be referred to as a parallel plate type.

[0226] The high-frequency electric field is preferably applied using a parallel-plate type high-frequency dielectric heating device. In the case of a parallel-plate type high-frequency dielectric heating device, the high-frequency electric field penetrates the high-frequency dielectric heating adhesive located between the electrodes, so that the high-frequency dielectric heating adhesive can be heated as a whole, and the adherend and the high-frequency dielectric heating adhesive can be bonded in a short time. In addition, in the case of manufacturing a laminated body as a structure, it is preferred to use a parallel-plate type high-frequency dielectric heating device.

[0227] A high frequency power source 53 for applying a high frequency electric field of, for example, about 13.56 MHz, about 27.12 MHz, or about 40.68 MHz is connected to the first high frequency electric field applying electrode 51 and the second high frequency electric field applying electrode 52 .

[0228] like Figure 4 As shown, the dielectric heating device 50 performs dielectric heating treatment by means of the high-frequency dielectric heating adhesive 1A sandwiched between the first adherend 110 and the second adherend 120. In addition to the dielectric heating treatment, the dielectric heating device 50 also joins the first adherend 110 and the second adherend 120 by a pressurization treatment using the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52. It should be noted that, in the case of not performing a pressurization treatment, two or more adherends may be joined by, for example, squeezing only by the high-frequency dielectric heating adhesive or the self-weight of the adherends.

[0229] When a high-frequency electric field is applied between the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52, the high-frequency dielectric heating adhesive 1A absorbs high-frequency energy. As a result, the thermoplastic resin component in the high-frequency dielectric heating adhesive 1A melts, and the first adherend 110 and the second adherend 120 can be firmly bonded even in a short-time treatment.

[0230] It should be noted that, when the high-frequency dielectric heating adhesive 1A contains a dielectric filler (not shown), the dielectric filler dispersed in the adhesive component absorbs high-frequency energy. Therefore, the dielectric filler functions as a heat source, and the thermoplastic resin component is melted by the heat generated by the dielectric filler, so that the first adherend 110 and the second adherend 120 can be firmly bonded even in a short-term treatment.

[0231] Since the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 have a pressurizing mechanism, they also function as a pressurizing device. Therefore, by applying pressure in the compression direction by the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 and heating and melting the high-frequency dielectric heating adhesive 1A, the first adherend 110 and the second adherend 120 can be more firmly bonded. It should be noted that in the description of the manufacturing method of the structure, the manufacturing method is listed. Figure 2 The case of the structure 100 shown is described as an example, but the present invention is not limited to this example.

[0232] (High frequency dielectric heating conditions)

[0233] The high-frequency dielectric heating conditions can be changed appropriately, but are preferably the following conditions.

[0234] The output power of the high-frequency electric field is preferably 10 W or more, more preferably 30 W or more, further preferably 50 W or more, and even more preferably 80 W or more.

[0235] The output power of the high-frequency electric field is preferably 50,000 W or less, more preferably 20,000 W or less, further preferably 15,000 W or less, further preferably 10,000 W or less, further preferably 1,000 W or less.

[0236] When the output power of the high-frequency electric field is 10 W or more, it is possible to prevent the problem that the temperature is difficult to rise during the dielectric heating treatment, and thus it is easy to obtain good bonding strength.

[0237] When the output power of the high-frequency electric field is 50000 W or less, it is easy to prevent the disadvantage that the temperature control becomes difficult due to the dielectric heating treatment.

[0238] The high-frequency electric field is preferably applied for a time period of 1 second or longer.

[0239] The application time of the high-frequency electric field is preferably 300 seconds or less, more preferably 240 seconds or less, further preferably 180 seconds or less, further preferably 120 seconds or less, further preferably 90 seconds or less, and particularly preferably 50 seconds or less.

[0240] When the high-frequency electric field is applied for 1 second or longer, it is possible to prevent the problem that the temperature is difficult to rise during the dielectric heating treatment, and thus it is easy to obtain good adhesive strength.

[0241] When the application time of the high-frequency electric field is 300 seconds or less, it is easy to prevent disadvantages such as a decrease in the manufacturing efficiency of the structure, an increase in the manufacturing cost, and thermal degradation of the adherend.

[0242] The frequency of the high-frequency electric field to be applied is more preferably 1 kHz or higher, more preferably 1 MHz or higher, more preferably 3 MHz or higher, further preferably 5 MHz or higher, and further preferably 10 MHz or higher.

[0243] The frequency of the applied high-frequency electric field is preferably 300 MHz or less, more preferably 100 MHz or less, further preferably 80 MHz or less, and further preferably 50 MHz or less. Specifically, the industrial frequency bands 13.56 MHz, 27.12 MHz, or 40.68 MHz allocated by the International Telecommunication Union can also be used for the manufacturing method and bonding method based on high-frequency dielectric heating of this embodiment.

[0244] [Effects of this embodiment]

[0245] The present embodiment is that the adhesive for high-frequency dielectric heating has a thermoplastic resin (A) containing a styrene copolymer resin (a1), and the tensile elastic modulus satisfies a specific lower limit, so the strength characteristics of the adhesive for high-frequency dielectric heating are improved. In addition, when the adherend contains a styrene resin, it can be more firmly bonded to the adherend. In addition, the dielectric properties of the adhesive for high-frequency dielectric heating of the present embodiment satisfy the above-mentioned lower limit, so more than one adherend can be firmly bonded together in a short time. According to the present embodiment, a structure to which more than one adherend is bonded by the adhesive for high-frequency dielectric heating and a method for manufacturing the structure can be improved. According to the method for manufacturing the structure, a structure to which more than one adherend is bonded can be manufactured in a short time.

[0246] The high-frequency dielectric heating adhesive of this embodiment has excellent fracture toughness. Therefore, by using the high-frequency dielectric heating adhesive of this embodiment, the strength of the structure formed by bonding the high-frequency dielectric heating adhesive and the adherend is reduced less even when a strong impact is applied. As a structure, for example, assuming that Figure 3When a structure 200 is subjected to an impact bond strength test, a high impact bond strength can be expected. This is because, for example, when cracks exist in the high-frequency dielectric heating adhesive, cracks generated in the structure are unlikely to grow from the cracks as a starting point.

[0247] Compared with ordinary adhesives, adhesives for high-frequency dielectric heating are superior in water resistance and moisture resistance.

[0248] The high-frequency dielectric heating adhesive of this embodiment is locally heated by applying a high-frequency electric field. Therefore, according to the high-frequency dielectric heating adhesive of this embodiment, it is easy to prevent the entire adherend from being damaged during bonding with the adherend.

[0249] [Variations of Embodiments]

[0250] The present invention is not limited to the above-described embodiments, and the present invention may include modifications and improvements within the scope that can achieve the purpose of the present invention.

[0251] The high-frequency dielectric heating treatment is not limited to the dielectric heating device in which the electrodes are arranged opposite to each other as described in the above embodiment, and a grid electrode type high-frequency dielectric heating device may also be used. The grid electrode type high-frequency dielectric heating device has a grid electrode, and the grid electrode is alternately arranged with electrodes of a first polarity and electrodes of a second polarity that are opposite to the first polarity electrodes at regular intervals on the same plane. It should be noted that in the figure, for simplicity, an example of using a dielectric heating device in which the electrodes are arranged opposite to each other is shown.

[0252] Example

[0253] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples at all.

[0254] [Preparation of Adhesive for High-Frequency Dielectric Heating] (Examples 1 to 5 and Comparative Examples 1 to 4)

[0255] Materials for preparing an adhesive (adhesive sheet) for high-frequency dielectric heating were premixed in the composition shown in Table 1. In Table 1, the adhesive sheet for high-frequency dielectric heating is referred to as an adhesive sheet.

[0256] The premixed material is supplied to the hopper of a 30 mm φ twin-screw extruder, and the barrel setting temperature and the die temperature are appropriately adjusted according to the type of thermoplastic resin (A), and the premixed material is melt-kneaded. The melt-kneaded material is cooled, and then the material is cut to produce granular pellets. Next, the produced granular pellets are put into the hopper of a single-screw extruder equipped with a T-die, and the barrel temperature and the die temperature are appropriately adjusted according to the type of thermoplastic resin (A), and a film-like molten kneaded product is extruded from the T-die, and cooled by a cooling roller, thereby producing sheet-like high-frequency dielectric heating adhesives (adhesive sheets for high-frequency dielectric heating) with a thickness of 400 μm of Examples 1 to 5 and Comparative Examples 1 to 4, respectively.

[0257] The description of the thermoplastic resin (A) and the dielectric filler (B) shown in Table 1 is as follows. In Table 1, the content of the styrene-based monomer unit is expressed as st monomer amount.

[0258] - Thermoplastic resin (A) -

[0259] Styrene copolymer resin (a1)

[0260] SEBS-1: Styrene-ethylene / butylene-styrene copolymer (manufactured by Asahi Kasei Corporation, trade name "TUFTECH 1043", content of styrene monomer units: 67% by mass)

[0261] SEBS-2: Styrene-ethylene / butylene-styrene copolymer (manufactured by Asahi Kasei Corporation, trade name "TUFTECH 1053", content of styrene monomer units: 29% by mass)

[0262] SEBS-3: Styrene-ethylene / butylene-styrene copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name "Espolex SB-2400")

[0263] SBS: Styrene-butadiene-styrene copolymer (manufactured by Asahi Kasei Corporation, trade name "Tufprene 126S", content of styrene monomer units 40% by mass)

[0264] SIS: Styrene-isoprene-styrene copolymer (manufactured by Zeon Co., Ltd., trade name "Quintac 3390", content of styrene monomer units: 48% by mass)

[0265] SEBS-1, SEBS-2 and SEBS-3 are hydrogenated products of styrene copolymer resins, while SBS and SIS are unhydrogenated products of styrene copolymer resins.

[0266] Other thermoplastic resins (a2)

[0267] GPPS: general-purpose polystyrene resin (manufactured by PS Japan Co., Ltd., trade name "HF77", content of styrene monomer units: 100% by mass)

[0268] Random PP: Random polypropylene resin (manufactured by Prime Polymer Co., Ltd., trade name "Prime Polypro J705UG", content of styrene monomer units 0 mass %)

[0269] -Dielectric filler (B)-

[0270] ZnO: zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name “LP-ZINC11”).

[0271] (Volume average particle size of dielectric filler)

[0272] The particle size distribution of the dielectric filler was measured by laser diffraction / scattering method. Based on the results of the particle size distribution measurement, the volume average particle size was calculated in accordance with JIS Z 8819-2: 2001. The calculated volume average particle size of zinc oxide (ZnO) was 11 μm.

[0273] Adhesive

[0274] A sheet of general-purpose polystyrene resin (manufactured by Kyoei Plastics Co., Ltd., product name “Dialite PS 201B-W1001”).

[0275] [Evaluation of adhesives for high-frequency dielectric heating]

[0276] The adhesive (adhesive sheet) for high-frequency dielectric heating was evaluated as shown below. The evaluation results are shown in Table 2.

[0277] (Tensile elastic modulus, tensile elongation at break)

[0278] The produced high-frequency dielectric heating adhesive sheet was cut into test pieces with a length of 150 mm (TD direction) and a width of 15 mm (MD direction). The test piece was clamped with the chuck of the testing machine, and the tensile modulus (MPa) and the tensile elongation at break (%) at 23 ° C were measured according to JIS K 7161-1: 2014 and JIS K 7127: 1999. The tensile modulus (MPa) and the tensile elongation at break (%) were measured using a tensile testing machine (Autograph AG-IS500N, manufactured by Shimadzu Corporation). The distance between the chucks was set to 100 mm. The tensile speed in the measurement of the tensile modulus (MPa) and the tensile elongation at break (%) was set to 200 mm / min.

[0279] (Dielectric properties)

[0280] The produced high-frequency dielectric heating adhesive sheet was cut into a size of 30 mm in length and 30 mm in width. For the cut high-frequency dielectric heating adhesive sheet, the dielectric material test fixture 16453A (made by Agilent) was installed in the RF impedance / material analyzer E4991A (made by Agilent), and the relative dielectric constant (ε'r) and dielectric loss tangent (tanδ) were measured by the parallel plate method at 23°C and a frequency of 40.68MHz. The value of the dielectric property (tanδ / ε'r) was calculated based on the measurement results.

[0281] (Flow start temperature)

[0282] The flow start temperature of the produced high-frequency dielectric heating adhesive sheet was measured using a descending rheometer (manufactured by Shimadzu Corporation, model "CFT-100D"). The load was set to 5 kg, a die with a hole shape of φ2.0 mm and a length of 5.0 mm was used, and a barrel with an inner diameter of 11.329 mm was used. The temperature of the measured sample was increased at a heating rate of 10°C / min, and the measurement was performed in a measurement temperature range of 30°C to 300°C. The stroke displacement velocity (mm / min) that changed with the temperature increase was measured, and a temperature dependence curve of the stroke displacement velocity of the sample was obtained. The flow start temperature is read from the curve. In this curve, the temperature at which the stroke displacement velocity starts to rise again after the peak obtained on the low temperature side is taken as the flow start temperature.

[0283] (Right-angle tear strength)

[0284] By punching the produced high-frequency dielectric heating adhesive sheet, a test piece with the shape and size specified in JIS K 7128-3:1998 was collected. The tear strength (right-angle tear strength) based on the right-angle method of the high-frequency dielectric heating adhesive sheet was measured according to the JIS standard. The right-angle tear strength was measured using a tensile testing machine (Autograph AG-IS 500N, manufactured by Shimadzu Corporation). The clamping part of the above-mentioned test piece was installed in the fixture of the testing machine, stretched at a tensile speed of 200mm / min, and the maximum load F (N) was read. The right-angle tear strength T (N / mm) is calculated based on the value obtained by dividing the maximum load F by the thickness d (mm) of the test piece (right-angle tear strength T = maximum load F / thickness d of the test piece).

[0285] (Weather resistance test)

[0286] A test piece having the same shape and size as the above-mentioned right-angle tear strength test piece was prepared separately for weather resistance test. The prepared test piece was subjected to weather resistance test using an ultra-accelerated weather resistance tester (EYESUPER UV TESTER SUV-W161 manufactured by Iwasaki Electric Co., Ltd.). The test conditions were as follows: a metal halide lamp was used, and the illumination was set to 90 mW / cm 2 The irradiation time was set to 48 hours, the back sheet temperature during irradiation was set to 63° C., and the relative humidity in the room was set to 70% RH. The above-mentioned right-angle tear test was carried out using the irradiated test piece.

[0287] It should be noted that, for Example 4 and Example 5, the test pieces were deteriorated due to the weathering test, so the right-angle tear test after the weathering test could not be performed. In addition, for Comparative Examples 2, 3 and 4, since the evaluation of the adhesiveness described later was F, the right-angle tear test after the weathering test was not performed.

[0288] (Adhesion)

[0289] First, the prepared high-frequency dielectric heating adhesive (adhesive sheet) was cut into a size of 25 mm in length and 12.5 mm in width. As adherends, two of the above-mentioned polystyrene resin sheets were prepared, each cut into a size of 25 mm in length, 100 mm in width, and 2 mm in thickness. The adhesive sheets cut into the above-mentioned sizes were arranged between the two adherends and stacked.

[0290] Next, the adherend and the adhesive sheet stacked in this way were fixed between two electrodes of a high-frequency dielectric heating device (manufactured by Yamamoto Vinita Co., Ltd., product name "YRP-400T-A"). In the fixed state, a high-frequency electric field was applied under the following high-frequency application conditions to bond the high-frequency dielectric heating adhesive sheet to the adherend, thereby preparing a test piece for evaluating adhesion. The pressure applied when applying the high-frequency electric field is the initial setting value of the pressure applied to the adhesive sheet.

[0291] ·High frequency electric field application conditions

[0292] Frequency: 40.68MHz

[0293] Output power: 250W

[0294] Application time: 20 seconds

[0295] Pressing pressure: 0.52MPa

[0296] For the obtained test piece, the tensile shear force (unit: MPa) as the adhesive force was measured. The tensile shear force was measured using a universal tensile testing machine (Instron 5581). The tensile speed during the measurement of the tensile shear force was set to a tensile speed of 100 mm / min. The tensile shear force was measured in accordance with JIS K 6850:1999.

[0297] The adhesiveness of the produced test pieces for adhesiveness evaluation was evaluated according to the following criteria.

[0298] A: The bonding strength is 1 MPa or more, or the bond is broken by the adherend.

[0299] F: The bonding strength is less than 1 MPa, or peeling occurs at the interface between the adhesive sheet and the adherend.

[0300] The bonding strength of the test pieces for evaluation was 1 MPa or more in all cases.

[0301]

[0302]

[0303] The results of adhesion and right-angle tear strength of each example are superior to those of each comparative example. The above results show that the high-frequency dielectric heating adhesive of this embodiment can achieve short-time bonding and can obtain a high-frequency dielectric heating adhesive with improved fracture toughness.

Claims

1. An adhesive for high-frequency dielectric heating, comprising a thermoplastic resin (A) and a dielectric filler (B) that generates heat by applying a high-frequency electric field, The thermoplastic resin (A) comprises a styrene copolymer resin (a1), The content of the styrene copolymer resin (a1) in the thermoplastic resin (A) is 40% by volume or more and 100% by volume or less, The content of the styrene monomer unit in the styrene copolymer resin (a1) is 10% by mass or more and 90% by mass or less, The volume content of the dielectric filler (B) in the high-frequency dielectric heating adhesive is 5 volume % or more and 50 volume % or less, The tensile elastic modulus of the high-frequency dielectric heating adhesive is 20 MPa or more. The dielectric property (tanδ / ε'r) of the high-frequency dielectric heating adhesive is greater than 0.

005. tanδ is the dielectric loss tangent at 23°C and a frequency of 40.68MHz. ε'r is the relative dielectric constant at 23°C and a frequency of 40.68 MHz.

2. The adhesive for high-frequency dielectric heating according to claim 1, wherein: The dielectric filler (B) is at least one selected from zinc oxide, silicon carbide, titanium oxide and barium titanate.

3. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The high-frequency dielectric heating adhesive has a flow start temperature of 80° C. or higher and 250° C. or lower.

4. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The styrene copolymer resin (a1) is a styrene elastomer.

5. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The styrene copolymer resin (a1) is a hydrogenated resin.

6. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The thermoplastic resin (A) further includes a thermoplastic resin (a2) different from the styrene-based copolymer resin (a1).

7. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The content of the styrene-based copolymer resin (a1) is 20% by volume or more and 98% by volume or less based on the total volume of the high-frequency dielectric heating adhesive.

8. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The high-frequency dielectric heating adhesive is used by applying a high-frequency electric field of 3 MHz to 300 MHz.

9. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The high-frequency dielectric heating adhesive is an adhesive used to join one or more adherends. Among the one or more adherends, at least one adherend contains a resin having an aromatic ring.

10. The adhesive for high-frequency dielectric heating according to claim 9, wherein: The resin having an aromatic ring is a styrene resin.

11. The adhesive for high-frequency dielectric heating according to claim 1 or 2, wherein: The adhesive for high-frequency dielectric heating is an adhesive sheet.

12. The adhesive for high-frequency dielectric heating according to claim 11, wherein: The adhesive sheet has a thickness of 5 μm or more and 2000 μm or less. 13 . A structure comprising one or more adherends joined to each other via the adhesive for high-frequency dielectric heating according to claim 1 .

14. A method for manufacturing a structure, the method comprising: A step of disposing the high-frequency dielectric heating adhesive according to any one of claims 1 to 12 on one or more adherends; as well as A step of applying a high-frequency electric field of 3 MHz to 300 MHz to the high-frequency dielectric heating adhesive to bond the adherends.

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