Adhesive for high-frequency dielectric heating

Abstract

Provided is an adhesive (adhesive sheet 1A) for high-frequency dielectric heating, which contains at least a thermoplastic resin (A) and a dielectric filler (B) that generates heat by application of a high-frequency electric field, the thermoplastic resin (A) including at least a first thermoplastic resin (A1) and a second thermoplastic resin (A2), the first thermoplastic resin (A1) being a silane-modified thermoplastic resin, and the second thermoplastic resin (A2) being a silane-modified thermoplastic resin. The second thermoplastic resin (A2) is a non-silane-modified thermoplastic resin.

Description

[0001] This application is a divisional application of an application with an application date of June 25, 2021, application number 202180047055.6, and invention name “Adhesive for high-frequency dielectric heating”. Technical Field

[0002] The present invention relates to an adhesive for high-frequency dielectric heating. Background Art

[0003] In recent years, as a method of bonding adherends that are usually difficult to bond, methods have been proposed, such as sandwiching an adhesive made of a heat-generating material blended in a given resin between the adherends and performing dielectric heating treatment, induction heating treatment, ultrasonic welding treatment, or laser welding treatment.

[0004] As a bonding method when using glass as an adherend, there are the following techniques.

[0005] For example, in Patent Document 1, as a thermoplastic resin composition for bonding glass to an inorganic reinforced thermoplastic resin, there is described a thermoplastic resin composition containing a heating element that generates heat under high-frequency induction and a thermoplastic resin having a melting point of 90°C to 200°C, wherein the thermoplastic resin is modified using a monomer containing a functional group that reacts with an inorganic substance in the presence of water.

[0006] In addition, as another bonding method, for example, Patent Document 2 describes a glass bonding sheet for bonding to a glass surface by vacuum lamination, the glass bonding sheet comprising a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound and a low-density polyethylene.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2002-097445

[0010] Patent Document 2: Japanese Patent Application Publication No. 2016-068426 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] When the thermoplastic resin composition described in Patent Document 1 is used, the energy consumption required for bonding to glass is large, and when the glass adhesive sheet described in Patent Document 2 is used, the pressure holding time required for bonding to glass during vacuum lamination is long. In addition, it is also required that the composition and sheet used for bonding to glass do not decrease in adhesive strength during storage after production until use.

[0013] An object of the present invention is to provide an adhesive for high-frequency dielectric heating that can be bonded to glass with high bonding strength even with low energy consumption and is unlikely to experience a decrease in bonding strength over time.

[0014] Solutions to the problem

[0015] According to one embodiment of the present invention, there is provided an adhesive for high-frequency dielectric heating, which contains at least a thermoplastic resin (A) and a dielectric material that generates heat by applying a high-frequency electric field, wherein the thermoplastic resin (A) contains at least a first thermoplastic resin (A1) and a second thermoplastic resin (A2), the first thermoplastic resin (A1) is a silane-modified thermoplastic resin, and the second thermoplastic resin (A2) is a thermoplastic resin that is not silane-modified.

[0016] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the first thermoplastic resin (A1) is a silane-modified polyolefin-based resin.

[0017] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the second thermoplastic resin (A2) is a non-silane-modified polyolefin-based resin.

[0018] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, the second thermoplastic resin (A2) preferably has a polar site.

[0019] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the polar site of the second thermoplastic resin (A2) is an acidic site.

[0020] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, it is preferred that the polar part of the second thermoplastic resin (A2) is an acid anhydride structure.

[0021] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the first thermoplastic resin (A1) is mainly composed of ethylene or propylene.

[0022] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the second thermoplastic resin (A2) is mainly composed of ethylene or propylene.

[0023] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, it is preferred that the main composition of the first thermoplastic resin (A1) and the main composition of the second thermoplastic resin (A2) are the same.

[0024] In the high-frequency dielectric heating adhesive of one embodiment of the present invention, the volume content of the first thermoplastic resin (A1) in the thermoplastic resin (A) contained in the high-frequency dielectric heating adhesive is preferably 15 volume % or more and 80 volume % or less.

[0025] In the high-frequency dielectric heating adhesive according to one embodiment of the present invention, the thermoplastic resin (A) preferably has an MFR at 190° C. of 2 g / 10 min or more and 50 g / 10 min or less.

[0026] In the high-frequency dielectric heating adhesive according to one aspect of the present invention, it is preferred that the volume content of the dielectric material in the high-frequency dielectric heating adhesive is 5 volume % or more and 50 volume % or less.

[0027] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the dielectric material is a dielectric filler (B).

[0028] In the adhesive for high-frequency dielectric heating according to one embodiment of the present invention, it is preferred that the dielectric filler (B) includes at least one selected from the group consisting of zinc oxide, silicon carbide, barium titanate, and titanium oxide.

[0029] In one embodiment of the high-frequency dielectric heating adhesive of the present invention, the volume average particle size of the dielectric filler (B) is preferably greater than or equal to 1 μm and less than or equal to 30 μm, and the volume average particle size is a volume average particle size obtained by measuring the particle size distribution of the dielectric filler (B) by a laser diffraction / scattering method and calculated based on the results of the particle size distribution measurement and based on JIS Z 8819-2:2001.

[0030] The adhesive for high-frequency dielectric heating according to one embodiment of the present invention is preferably an adhesive sheet.

[0031] According to one embodiment of the present invention, it is possible to provide an adhesive for high-frequency dielectric heating that can be bonded to glass with high bonding strength even with low energy consumption and in which the adhesive strength is unlikely to decrease over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1A The diagram is a cross-sectional view of a high-frequency dielectric heating adhesive sheet according to an embodiment.

[0033] Figure 1B The diagram is a cross-sectional view of a high-frequency dielectric heating adhesive sheet according to an embodiment.

[0034] Figure 1C The diagram is a cross-sectional view of a high-frequency dielectric heating adhesive sheet according to an embodiment.

[0035] Figure 2This is a schematic diagram for explaining a high-frequency dielectric heating process using a high-frequency dielectric heating adhesive sheet and a dielectric heating device according to one embodiment.

[0036] Figure 3A It is a schematic perspective view showing an example of the form of a molded body according to one embodiment.

[0037] Figure 3B It is a schematic perspective view showing an example of the form of a molded body according to one embodiment.

[0038] Figure 3C It is a schematic perspective view showing an example of the form of a molded body according to one embodiment.

[0039] Explanation of symbols

[0040] 10…adhesive layer (first adhesive layer), 10D…first part, 10E…first part, 10F…first part, 11…first surface, 12…second surface, 110…first adherend, 120…second adherend, 1A…high-frequency dielectric heating adhesive sheet, 1B…high-frequency dielectric heating adhesive sheet, 1C…high-frequency dielectric heating adhesive sheet, 1D…molded body, 1E…molded body, 1F…molded body, 20…adhesive layer (second adhesive layer), 20D…second part, 20E…second part, 20F…second part, 21…second surface, 30…substrate, 40…intermediate layer, 50…dielectric heating adhesive device, 51…first high-frequency electric field applying electrode, 52…second high-frequency electric field applying electrode, 53…high-frequency power supply. DETAILED DESCRIPTION

[0041] [Adhesive for high frequency dielectric heating]

[0042] The high-frequency dielectric heating adhesive of this embodiment contains at least a thermoplastic resin (A) and a dielectric material that generates heat by applying a high-frequency electric field. The thermoplastic resin (A) contains at least a first thermoplastic resin (A1) and a second thermoplastic resin (A2). The first thermoplastic resin (A1) is a silane-modified thermoplastic resin, and the second thermoplastic resin (A2) is another thermoplastic resin different from the silane-modified thermoplastic resin.

[0043] A high-frequency electric field refers to an electric field that reverses direction at high frequencies.

[0044] The dielectric material is a material that generates heat by applying a high-frequency electric field, and is preferably a material that generates heat when a high-frequency electric field with a frequency range of 3 MHz or more and 300 MHz or less is applied. The dielectric material is preferably at least one of a dielectric resin and a dielectric filler (B). From the viewpoint of easily suppressing the degradation of the dielectric material contained in the high-frequency dielectric heating adhesive sheet when processing the high-frequency dielectric heating adhesive sheet, the dielectric material is more preferably a dielectric filler (B).

[0045] Hereinafter, a case where the high-frequency dielectric heating adhesive sheet of the present embodiment includes a dielectric filler (B) as a dielectric material will be described.

[0046] <Thermoplastic resin (A)>

[0047] In the present embodiment, the high-frequency dielectric heating adhesive contains at least two thermoplastic resins (A). In the present embodiment, the high-frequency dielectric heating adhesive contains at least a first thermoplastic resin (A1) and a second thermoplastic resin (A2).

[0048] In the present embodiment, the first thermoplastic resin (A1) is a silane-modified thermoplastic resin. The silane-modified thermoplastic resin as the first thermoplastic resin (A1) is not particularly limited as long as it is a silane-modified thermoplastic resin, and is preferably at least one selected from the group consisting of a copolymer of a silyl-containing compound and a thermoplastic resin, and a silane-modified thermoplastic resin obtained by graft polymerization of a thermoplastic resin using a silyl-containing compound.

[0049] In the present embodiment, the second thermoplastic resin (A2) is a thermoplastic resin that is not modified by silane. The second thermoplastic resin (A2) is not particularly limited as long as it is a thermoplastic resin that is not modified by silane.

[0050] The adhesive for high-frequency dielectric heating containing a silane-modified thermoplastic resin as the thermoplastic resin (A) easily obtains high adhesion to glass. However, the adhesive for high-frequency dielectric heating containing only a silane-modified thermoplastic resin as the thermoplastic resin is prone to reduced adhesion. The reduction in adhesion is considered to be caused by the cross-linking reaction between the reactive groups of the silane-modified thermoplastic resin that occurs over time due to the silane-modified thermoplastic resin's easy water absorption.

[0051] In the case where the high-frequency dielectric heating adhesive contains not only a silane-modified thermoplastic resin but also a thermoplastic resin that is not modified by silane as a thermoplastic resin, the undesirable decrease in adhesion over time can be suppressed. It can be considered that since the high-frequency dielectric heating adhesive of the present embodiment also contains a thermoplastic resin that is not modified by silane, the reactive groups are kept away from each other while suppressing the high-frequency dielectric heating adhesive from absorbing water, making the cross-linking reaction difficult to proceed. In addition, in the case where the high-frequency dielectric heating adhesive contains a silane-modified thermoplastic resin and a thermoplastic resin that is not modified by silane, it is easy to adjust the viscosity of the high-frequency dielectric heating adhesive, and it is easy to give the high-frequency dielectric heating adhesive processing adaptability.

[0052] The thermoplastic resins in the first thermoplastic resin (A1) and the second thermoplastic resin (A2) are preferably each independently at least one selected from the group consisting of polyolefin resins, styrene resins, polyacetal resins, polycarbonate resins, poly(meth)acrylic resins, polyamide resins, polyimide resins, polyvinyl acetate resins, phenoxy resins, and polyester resins, for example, from the viewpoint of being easily melted and having a given heat resistance.

[0053] The thermoplastic resin in the silane-modified thermoplastic resin is preferably a polyolefin resin. That is, the first thermoplastic resin (A1) is preferably a silane-modified polyolefin resin. When the first thermoplastic resin (A1) is a silane-modified polyolefin, it has excellent formability, and is easy to melt under high-frequency dielectric heating, and it is easy to obtain a high-frequency dielectric heating adhesive with high adhesion. It should be noted that the formability of the high-frequency dielectric heating adhesive indicates the ease of processing the high-frequency dielectric heating adhesive into a desired form (for example, a sheet or a molded body). In this specification, the high-frequency dielectric heating adhesive of this embodiment in the form of an adhesive sheet is sometimes referred to as a high-frequency dielectric heating adhesive sheet.

[0054] The thermoplastic resin in the thermoplastic resin not modified by silane is preferably a polyolefin resin. That is, the second thermoplastic resin (A2) is preferably a polyolefin resin not modified by silane. When the second thermoplastic resin (A2) is a polyolefin resin not modified by silane, it has excellent formability, is easily melted under high-frequency dielectric heating, and is easy to obtain a high-frequency dielectric heating adhesive with high adhesion. Since polyolefin itself has high hydrophobicity, the polyolefin resin not modified by silane also shows a significant effect in suppressing the decrease of adhesive performance over time.

[0055] More preferably, the first thermoplastic resin (A1) is a silane-modified polyolefin resin, and the second thermoplastic resin (A2) is a polyolefin resin that is not modified by silane. Silane-modified polyolefin resins have excellent compatibility with polyolefin resins that are not modified by silane. Therefore, by containing silane-modified polyolefin resins and polyolefin resins that are not modified by silane, it is easier to obtain an adhesive for high-frequency dielectric heating that has excellent moldability, high adhesiveness, and is not prone to a decrease in adhesive performance over time.

[0056] The silane-modified polyolefin resin is not particularly limited, and is preferably at least one selected from the group consisting of a copolymer of a silyl-containing compound and an olefin, and a silane-modified polyolefin obtained by graft-polymerizing a polyolefin with a silyl-containing compound.

[0057] The olefin copolymerized with the silyl group-containing compound is preferably, for example, an α-olefin having 2 to 20 carbon atoms, and the α-olefin having 2 to 20 carbon atoms is preferably, for example, at least one olefin selected from ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-pentene, and more preferably at least one olefin selected from ethylene and propylene. The olefin copolymerized with the silyl group-containing compound may be one kind or two or more kinds.

[0058] As the polyolefin graft polymerized by the silyl-containing compound, homopolymers of the above-mentioned olefins and copolymers of two or more olefins can be cited, preferably homopolymers or copolymers having monomer units derived from at least one of ethylene and propylene. In addition, silane-modified polyolefins prepared by graft polymerizing a polyolefin having a reactive group by the silyl-containing compound in advance are also preferred.

[0059] As the silyl group-containing compound, there can be cited: vinyl silanes such as vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tripropoxysilane, vinyl triisopropoxysilane, vinyl tributoxysilane, vinyl triphenoxysilane, vinyl triphenyloxysilane, vinyl trimethylenedioxysilane, vinyl propionyloxysilane, vinyl triacetoxysilane, vinyl tricarboxyl silane, vinyl triacetyl silane, vinyl trichlorosilane, vinyl trimethyl ethyl ketoxime silane, vinyl triisopropenyloxysilane, and vinyl methyl dimethoxysilane; (meth) acryl silanes such as (meth) acryloxymethyl trimethoxysilane; styryl silanes such as styryl trimethoxysilane, etc. It should be noted that in this specification, "(meth) acrylic acid" is a description adopted when both "acrylic acid" and "methacrylic acid" are represented, and the same applies to other similar terms.

[0060] The polyolefin resins in the first thermoplastic resin (A1) and the second thermoplastic resin (A2) are also preferably resins composed of homopolymers such as polyethylene, polypropylene, polybutene and polymethylpentene, and α-olefin resins composed of copolymers of monomers selected from ethylene, propylene, butene, hexene, octene and 4-methylpentene.

[0061] The main component of the first thermoplastic resin (A1) is preferably ethylene or propylene from the viewpoint of obtaining an adhesive for high-frequency dielectric heating having excellent mechanical strength, high moldability, and stable adhesive properties.

[0062] The main component of the second thermoplastic resin (A2) is preferably ethylene or propylene from the viewpoint of obtaining an adhesive for high-frequency dielectric heating having excellent mechanical strength, high moldability, and stable adhesive properties.

[0063] In this specification, the "main component of the thermoplastic resin" refers to the repeating unit with the largest content in the polymer among the repeating units contained in the polymer, for example, when the thermoplastic resin is a polymer derived from a single monomer, the monomer unit (repeating unit) is the "main component of the thermoplastic resin". When the thermoplastic resin is a copolymer, the repeating unit with the largest content in the polymer is the "main component of the thermoplastic resin". When the thermoplastic resin is a copolymer, in the copolymer, the "main component of the thermoplastic resin" is a repeating unit (monomer unit) with a content of 30% by mass or more, a repeating unit with a content of more than 30% by mass in one embodiment, a repeating unit with a content of 40% by mass or more in another embodiment, and a repeating unit with a content of 50% by mass or more in another embodiment. In addition, when the thermoplastic resin is a copolymer, the repeating units with the largest content may be two or more.

[0064] It is preferred that the main composition of the first thermoplastic resin (A1) and the main composition of the second thermoplastic resin (A2) are the same.

[0065] For example, when the first thermoplastic resin (A1) is a silane-modified polypropylene containing 50% by mass or more of propylene units as repeating units, and the second thermoplastic resin (A2) is also a maleic anhydride-modified polypropylene containing 50% by mass or more of propylene units as repeating units, the main component (repeating unit) of the first thermoplastic resin (A1) and the main component (repeating unit) of the second thermoplastic resin are both propylene, and the main components of the first thermoplastic resin (A1) and the second thermoplastic resin are the same.

[0066] By making the main composition of the first thermoplastic resin (A1) and the main composition of the second thermoplastic resin (A2) the same, the compatibility between the first thermoplastic resin (A1) and the second thermoplastic resin (A2) is improved, and the reactive groups of the first thermoplastic resin (A1) are more easily separated from each other.

[0067] The volume content of the first thermoplastic resin (A1) in the thermoplastic resin (A) contained in the high-frequency dielectric heating adhesive is preferably 15 volume % or more, more preferably 25 volume % or more, and further preferably 40 volume % or more.

[0068] The volume content of the first thermoplastic resin (A1) in the thermoplastic resin (A) contained in the high-frequency dielectric heating adhesive is preferably 80 volume % or less, more preferably 70 volume % or less, and further preferably 60 volume % or less.

[0069] When the volume content of the first thermoplastic resin (A1) in the thermoplastic resin (A) is 15 volume % or more, adhesion to glass can be easily obtained.

[0070] When the volume content of the first thermoplastic resin (A1) in the thermoplastic resin (A) is 80 volume % or less, storage stability is easily obtained.

[0071] The volume content of the second thermoplastic resin (A2) in the thermoplastic resin (A) contained in the high-frequency dielectric heating adhesive is preferably 20 volume % or more, more preferably 30 volume % or more, and even more preferably 40 volume % or more.

[0072] The volume content of the second thermoplastic resin (A2) in the thermoplastic resin (A) contained in the high-frequency dielectric heating adhesive is preferably 85 volume % or less, more preferably 75 volume % or less, and further preferably 60 volume % or less.

[0073] When the volume content of the second thermoplastic resin (A2) in the thermoplastic resin (A) is 20% by volume or more, the storage stability of the adhesive for high-frequency dielectric heating can be easily obtained.

[0074] By setting the volume content of the second thermoplastic resin (A2) in the thermoplastic resin (A) to 85 volume % or less, it is easy to prevent a decrease in adhesion to glass.

[0075] The total volume content of the first thermoplastic resin (A1) and the volume content of the second thermoplastic resin (A2) in the thermoplastic resin (A) contained in the high-frequency dielectric heating adhesive is 100% by mass or less.

[0076] The volume ratio of the first thermoplastic resin (A1) to the second thermoplastic resin (A2) in the adhesive for high-frequency dielectric heating is preferably 15:85 to 80:20, more preferably 25:75 to 70:30, and even more preferably 40:60 to 60:40.

[0077] The second thermoplastic resin (A2) preferably has a polar part. Examples of the polar part include hydroxyl, carboxyl, epoxy, acryloyl, acetoxy, sulfo, phospho, phenol, vinyl acetate structure, and anhydride structure. The polar part may be introduced into the resin by copolymerization or by modification. Thermoplastic resins having polar parts are preferred because they show high adhesion to adherends. The second thermoplastic resin (A2) is preferably a polyolefin resin having a polar part.

[0078] When the adhesive for high-frequency dielectric heating contains a first thermoplastic resin (A1) and a second thermoplastic resin (A2) having a polar portion, the volume ratio of the first thermoplastic resin (A1) to the second thermoplastic resin (A2) having a polar portion in the adhesive for high-frequency dielectric heating is preferably 15:85 to 80:20, more preferably 25:75 to 70:30, and further preferably 40:60 to 60:40.

[0079] The polar part of the second thermoplastic resin (A2) is also preferably an acidic part. More preferably, the second thermoplastic resin (A2) is a polyolefin resin having an acidic part. Examples of the acidic part of the second thermoplastic resin (A2) include a carboxyl group, a sulfonic group, a phospho group, a phenolic group, and an acid anhydride structure. By providing the second thermoplastic resin (A2) with an acidic part, it is possible to suppress the reduction in adhesive performance caused by a reduction in the proportion of the silane-modified thermoplastic resin in the adhesive for high-frequency dielectric heating.

[0080] The second thermoplastic resin (A2) is also preferably a resin having an acid-modified structure as a polar part, and more preferably a polyolefin resin having an acid-modified structure. 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 thermoplastic resin (e.g., a polyolefin resin), there can be cited: unsaturated carboxylic acid, an acid anhydride derived from an unsaturated carboxylic acid, and an unsaturated carboxylic acid ester of any compound. In this specification, a polyolefin resin having an acid-modified structure is sometimes referred to as an acid-modified polyolefin resin.

[0081] As unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, etc. are mentioned, for example.

[0082] As an anhydride of an unsaturated carboxylic acid, anhydrides of unsaturated carboxylic acids, such as maleic anhydride, itaconic anhydride and citraconic anhydride, etc. are mentioned, for example.

[0083] Examples of the ester of unsaturated carboxylic acid 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.

[0084] (Polyolefin resin having polar part)

[0085] 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 adhesive strength to an adherend.

[0086] The polyolefin resin having a polar part may be a copolymer of an olefin monomer and a monomer having a polar part. Alternatively, the polyolefin resin having a polar part may be a resin obtained by introducing a polar part into an olefin polymer obtained by polymerizing an olefin monomer through modification such as an addition reaction.

[0087] 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.

[0088] From the viewpoint of obtaining an adhesive for high-frequency dielectric heating having excellent mechanical strength and stable adhesive properties, the olefin-based monomer is preferably at least one of ethylene and propylene.

[0089] 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.

[0090] When the polyolefin resin as the second thermoplastic resin (A2) is a copolymer of an olefin monomer and a monomer having a polar site, the copolymer preferably contains 2% by mass or more of a structural unit derived from a monomer having a polar site, more preferably 4% by mass or more, further preferably 5% by mass or more, and further preferably 6% by mass or more. In addition, the copolymer preferably contains 30% by mass or less of a structural unit derived from a monomer having a polar site, more preferably 25% by mass or less, further preferably 20% by mass or less, and further preferably 15% by mass or less.

[0091] By making the copolymer contain 2% by mass or more of the structural unit derived from the monomer having the polar part, the bonding strength of the adhesive for high-frequency dielectric heating is improved. In addition, by making the copolymer contain 30% by mass or less of the structural unit derived from the monomer having the polar part, the viscosity of the second thermoplastic resin (A2) can be suppressed from becoming too strong. As a result, it is easy to prevent the molding process of the adhesive for high-frequency dielectric heating from becoming difficult.

[0092] When the polyolefin resin as the second thermoplastic resin (A2) is a copolymer of an olefin monomer and a monomer having an acidic part, the proportion of the structural units derived from the monomer having an acidic part in the copolymer is preferably in the same range as the proportion of the structural units derived from the monomer having a polar part in the case of a copolymer of an olefin monomer and a monomer having a polar part, and the effect obtained within this range is also the same as in the case where the polyolefin resin as the second thermoplastic resin (A2) is a copolymer of an olefin monomer and a monomer having a polar part.

[0093] When the polyolefin resin as the second thermoplastic resin (A2) has an acid-modified structure, the modification rate with acid is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more.

[0094] When the polyolefin resin as the second thermoplastic resin (A2) has an acid-modified structure, the modification rate with acid is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less.

[0095] When the second thermoplastic resin (A2) has an acid-modified structure, the bonding strength of the adhesive for high-frequency dielectric heating is improved by making the modification rate based on the acid to be 0.01% by mass or more. In addition, by making the modification rate based on the acid to be 30% by mass or less, the viscosity of the second thermoplastic resin (A2) can be prevented from becoming too strong. As a result, it is easy to prevent the molding process of the adhesive for high-frequency dielectric heating from becoming difficult.

[0096] In the present specification, the modification ratio based on acid refers to the percentage of the mass of the portion derived from the acid relative to the total mass of the acid-modified polyolefin.

[0097] The acidic part of the second thermoplastic resin (A2) is preferably an anhydride structure. More preferably, the second thermoplastic resin (A2) is a polyolefin resin having an anhydride structure. By making the second thermoplastic resin (A2) have an anhydride structure, the interaction with the dielectric filler (B) can be suppressed, thereby suppressing the torque increase and gelation when the high-frequency dielectric heating adhesive is sheet-formed.

[0098] The acid anhydride structure is more preferably a maleic anhydride structure. The maleic anhydride structure may be a group introduced by graft modification of a thermoplastic resin, or may be a maleic anhydride copolymer obtained by copolymerizing a monomer containing a maleic anhydride structure.

[0099] In the maleic anhydride-modified polyolefin, the modification rate based on maleic anhydride is preferably in the same range as the modification rate when the polyolefin resin as the second thermoplastic resin (A2) has an acid-modified structure, and the effect obtained within this range is also the same as when the polyolefin resin as the second thermoplastic resin (A2) has an acid-modified structure.

[0100] In the case where the maleic anhydride-modified polyolefin is a copolymer comprising an olefin monomer and a monomer having a maleic anhydride structure, the ratio of the structural unit derived from the monomer having a maleic anhydride structure in the copolymer is preferably in the same range as the ratio of the structural unit derived from the monomer having a polar part in the case where it is a copolymer of an olefin monomer and a monomer having a polar part. The effect obtained within this range is also the same as in the case where the polyolefin resin as the second thermoplastic resin (A2) is a copolymer of an olefin monomer and a monomer having a polar part.

[0101] The structural unit derived from olefin in the maleic anhydride-modified polyolefin is preferably a structural unit derived from ethylene or propylene. That is, the maleic anhydride-modified polyolefin is preferably a maleic anhydride-modified polyethylene resin or a maleic anhydride-modified polypropylene resin.

[0102] (MFR of thermoplastic resin)

[0103] The MFR of the thermoplastic resin (A) at 190° C. is preferably 2 g / 10 min or more, more preferably 2.5 g / 10 min or more, and even more preferably 3 g / 10 min or more.

[0104] The MFR of the thermoplastic resin (A) at 190° C. is preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, and even more preferably 20 g / 10 min or less.

[0105] When the MFR of the thermoplastic resin (A) at 190° C. is 2 g / 10 min or more, excellent sheet moldability is achieved and the wet spread of the adhesive for high-frequency dielectric heating during bonding is good, so that bonding strength can be easily obtained in a short time.

[0106] By making the MFR of the thermoplastic resin (A) at 190°C 50 g / 10 min or less, it is easy to prevent the viscosity of the high-frequency dielectric heating adhesive from becoming too low during the dielectric heating treatment. When the viscosity of the high-frequency dielectric heating adhesive becomes too low, the amount of resin between the adherends will decrease during bonding, making it difficult to obtain bonding strength, but by preventing the viscosity from decreasing, it is easy to obtain bonding strength.

[0107] The MFR of the thermoplastic resin (A) at 190° C. can be measured by the method described in the section of Examples described later.

[0108] <Dielectric filler (B)>

[0109] The dielectric filler (B) is a filler that generates heat by application of a high-frequency electric field.

[0110] 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.

[0111] (type)

[0112] The dielectric filler (B) is suitably one of the following materials alone or in combination of two or more thereof: zinc oxide, silicon carbide (SiC), anatase titanium oxide, barium titanate, barium zirconate titanate, lead titanate, potassium niobate, rutile titanium oxide, hydrated aluminum silicate, inorganic materials having water of crystallization such as hydrated aluminum silicates of alkali metals, or inorganic materials having water of crystallization such as hydrated aluminum silicates of alkaline earth metals.

[0113] The dielectric filler (B) preferably includes at least one selected from zinc oxide, silicon carbide, barium titanate, and titanium oxide.

[0114] Among the dielectric fillers exemplified, zinc oxide is further preferred as the dielectric filler (B) because of its rich variety, various shapes and sizes, and the ability to improve the bonding properties and mechanical properties of the high-frequency dielectric heating adhesive in accordance with the intended use. By using zinc oxide as the dielectric filler (B), a colorless high-frequency dielectric heating adhesive can be obtained. Among dielectric fillers, zinc oxide has a low density. Therefore, when the adherend is bonded using a high-frequency dielectric heating adhesive containing zinc oxide as the dielectric filler (B), the total weight of the bonded body is less likely to increase compared to the case where an adhesive containing other dielectric fillers is used. Zinc oxide has a low hardness among ceramics, and therefore, 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.

[0115] 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.

[0116] (Volume content)

[0117] 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.

[0118] 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.

[0119] When the volume content of the dielectric filler (B) in the adhesive for high-frequency dielectric heating is 5 volume % or more, the heat generation property is improved, and the adhesive for high-frequency dielectric heating and a glass adherend can be firmly bonded easily.

[0120] By setting the volume content of the dielectric filler (B) in the high-frequency dielectric heating adhesive to 50 volume % or less, it is easy to obtain flexibility when made into a sheet and to prevent a decrease in toughness. Therefore, it is easy to process the high-frequency dielectric heating adhesive into a desired shape in subsequent steps.

[0121] It should be noted that, in the adhesive for high-frequency dielectric heating of the present embodiment, since the thermoplastic resin (A) and the dielectric filler (B) are included, 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).

[0122] In the above, as the volume content of the dielectric material in the adhesive layer, the volume content in the case where the dielectric material is the dielectric filler (B) is described. However, the volume content of the dielectric material in the adhesive layer is not limited to the case where the dielectric material is the dielectric filler (B), and in the case of a dielectric material other than the dielectric filler (B), it is also suitable to be in the same range as the volume content of the dielectric filler (B) in the adhesive layer. That is, the volume content of the dielectric material in the adhesive layer is preferably 5 volume % or more and preferably 50 volume % or less.

[0123] (Average particle size)

[0124] 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.

[0125] 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.

[0126] When the volume average particle size of the dielectric filler (B) is 1 μm or more, the high-frequency dielectric heating adhesive exhibits high heat generation performance when a high-frequency electric field is applied, and the high-frequency dielectric heating adhesive can be strongly bonded to a glass adherend in a short time.

[0127] 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 high-frequency dielectric heating adhesive can be strongly bonded to a glass adherend in a short time. In addition, 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 can be prevented from decreasing.

[0128] The volume average particle size of the dielectric filler (B) can be measured by the following method: The particle size distribution of the dielectric filler (B) is measured by 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.

[0129] When the adhesive for high-frequency dielectric heating of the present embodiment is an adhesive sheet (high-frequency dielectric heating adhesive sheet), it is preferable that the average particle size D of the dielectric filler (B) is 0.1-0.2mm. F The thickness T of the high frequency dielectric heating adhesive sheet satisfies 1≤T / D F Relationship ≤2500.

[0130] T / D F It is preferably 1 or more, preferably 2 or more, preferably 5 or more, more preferably 10 or more, and further preferably 20 or more. T / D F When the ratio is 1 or more, it is possible to prevent a decrease in bonding strength due to contact between the dielectric filler (B) and the adherend during bonding.

[0131] T / D F It is preferably 2500 or less, preferably 2000 or less, preferably 1750 or less, more preferably 1000 or less, further preferably 50 or less, further preferably 100 or less, and further more preferably 50 or less. T / D F When the molecular weight is 2500 or less, the burden on the sheet manufacturing apparatus when producing the high-frequency dielectric heating adhesive sheet can be suppressed.

[0132] (additive)

[0133] The high-frequency dielectric heating adhesive of the present embodiment may contain additives or may not contain additives. In the case where the high-frequency dielectric heating adhesive of the present embodiment is a high-frequency dielectric heating adhesive sheet composed of multiple layers, at least any one of the multiple layers may contain additives or may not contain additives. In the case where at least any one of the multiple layers contains additives, the adhesive layer containing the high-frequency dielectric heating adhesive in the multiple layers may contain additives or may not contain additives.

[0134] 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 material (dielectric filler).

[0135] Thickeners and plasticizers can improve the melting characteristics and bonding characteristics of adhesives for high-frequency dielectric heating.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] The high-frequency dielectric heating adhesive of the present embodiment preferably does not contain a solvent. When a high-frequency dielectric heating adhesive containing no solvent is used, the problem of VOC (Volatile Organic Compounds) caused by the adhesive used for bonding to the adherend is less likely to occur.

[0140] The high-frequency dielectric heating adhesive of this 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 adhesive layer preferably does not contain, for example, carbon steel, α iron, γ iron, δ iron, copper, brass, aluminum, iron-nickel alloy, iron-nickel-chromium alloy, carbon fiber and carbon black.

[0141] When 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 20 mass % or less, more preferably 10 mass % or less, further preferably 5 mass % or less, further preferably 1 mass % or less, and further preferably 0.1 mass % or less, each independently based on the total amount of the adhesive.

[0142] The content of the conductive substance in the adhesive is particularly preferably 0 mass %.

[0143] When the content of the conductive substance in the adhesive is 20% by mass or less, it is easy to prevent the problem of carbonization of the bonded portion and the adherend due to electrical insulation breakdown during dielectric heating treatment.

[0144] The total content of the thermoplastic resin (A) and the dielectric filler (B) in the high-frequency dielectric heating adhesive of the present embodiment is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 99% by mass or more.

[0145] <Form and characteristics of adhesive for high-frequency dielectric heating>

[0146] The form of the high-frequency dielectric heating adhesive of this embodiment is not particularly limited, for example, a sheet or a molded body. In this specification, a molded body is not a sheet. A sheet generally refers to a sheet material with a uniform thickness of less than 1 mm, less than 2 mm, or less than 5 mm.

[0147] (High frequency dielectric heating adhesive sheet)

[0148] The high-frequency dielectric heating adhesive of the present embodiment is preferably an adhesive sheet (high-frequency dielectric heating adhesive sheet). The high-frequency dielectric heating adhesive sheet of the present embodiment is composed of only one adhesive layer in one embodiment, and the adhesive layer is formed by the high-frequency dielectric heating adhesive of the present embodiment. In another embodiment, it is sometimes composed of multiple layers. In the case where the high-frequency dielectric heating adhesive sheet is composed of only one adhesive layer, the adhesive layer itself is equivalent to the high-frequency dielectric heating adhesive sheet, and therefore, the form and characteristics of the high-frequency dielectric heating adhesive sheet are equivalent to the form and characteristics of the adhesive layer.

[0149] As one form of the high-frequency dielectric heating adhesive sheet of this embodiment, it is composed of only a high-frequency dielectric adhesive adhesive layer. It should be noted that the high-frequency dielectric heating adhesive sheet is not limited to the form of only a bonding layer. As other forms of the high-frequency dielectric heating adhesive sheet, a form in which layers other than the bonding layer are stacked can also be listed.

[0150] As described above, a high-frequency dielectric heating adhesive sheet is sometimes composed of only a high-frequency dielectric adhesive layer. Therefore, in this specification, the terms "high-frequency dielectric heating adhesive sheet" and "adhesive layer" are sometimes interchangeable.

[0151] Figure 1A to Figure 1C The schematic diagrams illustrate various forms of the high-frequency dielectric heating adhesive sheet according to the present embodiment.

[0152] Figure 1A The high-frequency dielectric heating adhesive sheet 1A shown is composed of only a single adhesive layer 10. The high-frequency dielectric heating adhesive sheet 1A has a first surface 11 and a second surface 12 on the opposite side to the first surface 11.

[0153] The high-frequency dielectric heating adhesive sheet is preferably composed of only a single adhesive layer. By only being composed of a single adhesive layer, the thickness of the high-frequency dielectric heating adhesive sheet can be reduced and molding can be performed simply.

[0154] Figure 1B The high-frequency dielectric heating adhesive sheet 1B shown has an adhesive layer 10 and a substrate 30 supporting the adhesive layer 10. Similar to the high-frequency dielectric heating adhesive sheet 1A, the adhesive layer 10 has a first surface 11. The substrate 30 is not particularly limited as long as it is a member capable of supporting the adhesive layer 10, and examples thereof include: a resin film or resin sheet containing at least one or more resins selected from polyolefin resins such as polyethylene resins and polypropylene resins, polyester resins such as polybutylene terephthalate resins and polyethylene terephthalate resins, acetate resins, ABS resins, polystyrene resins, and vinyl chloride resins. The substrate 30 may also contain a dielectric filler (B), and the dielectric filler (B) in the adhesive layer 10 and the dielectric filler in the substrate 30 may be the same or different from each other.

[0155] Figure 1C The high-frequency dielectric heating adhesive sheet 1C shown has an adhesive layer 10, an adhesive layer 20, and an intermediate layer 40 disposed between the adhesive layer 10 and the adhesive layer 20. The high-frequency dielectric heating adhesive sheet 1C has a first surface 11 and a second surface 21 opposite to the first surface 11. The adhesive layer 10 in the high-frequency dielectric heating adhesive sheet 1C is sometimes referred to as a first adhesive layer, and the adhesive layer 20 is sometimes referred to as a second adhesive layer. In a high-frequency dielectric heating adhesive sheet having an intermediate layer arranged between a first adhesive layer and a second adhesive layer, as long as the first adhesive layer satisfies the conditions of the adhesive layer of the high-frequency dielectric heating adhesive sheet of this embodiment, in one embodiment, the first adhesive layer and the second adhesive layer are layers of the same composition and properties, in one embodiment, the second adhesive layer is a high-frequency dielectric heating adhesive layer that is different from the first adhesive layer in at least one aspect of the composition and properties, in one embodiment, the second adhesive layer is a layer of a general adhesive that is not a high-frequency dielectric heating adhesive layer, and the second adhesive layer that is not a high-frequency dielectric heating adhesive is, for example, a layer of a drying-setting adhesive that dries and solidifies upon evaporation of water or a solvent, or a layer of an adhesive formed by an adhesive (pressure-sensitive adhesive).

[0156] Thickness of high frequency dielectric heating adhesive sheet

[0157] The thickness of the high-frequency dielectric heating adhesive sheet of the present embodiment 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.

[0158] When the thickness of the high-frequency dielectric heating adhesive sheet is 5 μm or more, the high-frequency dielectric heating adhesive sheet can easily follow the irregularities of the adherend when bonding to the adherend, and can easily exhibit bonding strength.

[0159] When the high-frequency dielectric heating adhesive sheet has a multilayer structure composed of multiple 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.

[0160] When the high-frequency dielectric heating adhesive sheet is a multi-layered sheet, when 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.

[0161] The upper limit of the thickness of the high-frequency dielectric heating adhesive sheet is not particularly limited. Since the thickness of the high-frequency dielectric heating adhesive sheet increases, the weight of the entire joint body obtained by bonding the high-frequency dielectric heating adhesive sheet to the adherend also increases. Therefore, the high-frequency dielectric heating adhesive sheet is preferably a thickness within a range that does not cause problems in practical use. In addition, considering the practicality and formability of the high-frequency dielectric heating adhesive sheet, the thickness of the high-frequency dielectric heating adhesive sheet is preferably 2000 μm or less, more preferably 1000 μm or less, and further preferably 600 μm or less.

[0162] Compared with the case of using a liquid adhesive that requires coating, the adhesive sheet as an adhesive for high-frequency dielectric heating is easy to handle and the workability when joining to an adherend is also improved.

[0163] In addition, for the adhesive sheet used as the adhesive for high-frequency dielectric heating, the sheet thickness 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 adhesive sheet used as the adhesive for high-frequency dielectric heating also has significant advantages.

[0164] (Molding body)

[0165] The adhesive for high-frequency dielectric heating of the present embodiment is also preferably a molded body. The form of the molded body of the present embodiment is not particularly limited. Figure 3A to Figure 3C What is shown is a stereoscopic schematic diagram showing an example of the form of the molded body of the present embodiment. The molded body of the present embodiment may be a molded body consisting of a single part obtained by molding the high-frequency dielectric heating adhesive of the present embodiment, or may be a molded body consisting of multiple parts. For example, there may be a molded body having a first part formed of the high-frequency dielectric heating adhesive (first material) of the present embodiment, and a second part formed of a second material that is a material different from the first material of the first part.

[0166] Figure 3A The molded body 1D shown is in the shape of a cube and has a first portion 10D and a second portion 20D having a larger volume than the first portion 10D.

[0167] Figure 3B The shape of the molded body 1E shown is also a cube. The positions and proportions of the first parts of the molded body 1D and the molded body 1E in the cube are different. In the molded body 1D, the first part 10D is connected to the entire bottom surface of the second part 20D. On the other hand, in the molded body 1E, the first part 10E is located at the corner of the cube and connected to the second part 20E.

[0168] The molded body of this embodiment may also have a plurality of first parts. For example, Figure 3C The molded body 1F shown has a second portion 20F which is hollow and substantially cylindrical and partially cut out in the axial direction, and two first portions 10F which are in contact with the two cutout end surfaces of the second portion 20F. The number of first portions in the molded body is not limited to two, and may be three or more.

[0169] The form of the molded article of the present invention is not limited to the examples shown in the molded articles 1D, 1E, and 1F. In addition, in the examples shown in the molded articles 1D, 1E, and 1F, the first part and the second part are directly connected together, but the present invention is not limited to the form in which the first part and the second part are directly connected together, and the first part and the second part may also be connected together via other parts (for example, the third part, etc.).

[0170] In the molded body of the present embodiment, the second portion is formed of the second material.

[0171] The second material is not particularly limited. The second material preferably includes at least one material selected from, for example, an organic material, an inorganic material, and a natural source material. Examples of organic materials include thermoplastic resins and thermosetting resins. Examples of inorganic materials include ceramics, glass, and metals. Examples of natural source materials include wood, paper, leather, and stone.

[0172] In the molded body of the present embodiment, the first material is different from the second material. The first material is different from the second material means that all the components contained in the first material are inconsistent with all the components contained in the second material. For example, when the first material is a material containing a silane-modified thermoplastic resin (first thermoplastic resin (A1)), another thermoplastic resin different from the silane-modified thermoplastic resin (second thermoplastic resin (A2)), and zinc oxide, and the second material is a material containing only the silane-modified thermoplastic resin, since the second material does not contain other thermoplastic resins and zinc oxide, the first material and the second material are inconsistent in all components, and the first material and the second material are different.

[0173] (Method for producing adhesive for high-frequency dielectric heating)

[0174] The high-frequency dielectric heating adhesive of the present embodiment can be produced by, for example, mixing the above-mentioned components.

[0175] When the high-frequency dielectric heating adhesive of the present embodiment is an adhesive sheet, its manufacturing method is not particularly limited, and it can be manufactured, for example, as described below. The single-layer high-frequency dielectric heating adhesive sheet can be manufactured by premixing the above-mentioned components, kneading them using a known kneading device such as an extruder and a hot roll, and using a known molding method such as extrusion molding, calendering molding, injection molding, and cast molding.

[0176] When the high-frequency dielectric heating adhesive sheet of the present embodiment is a multilayer structure, for example, the above-mentioned components can be premixed and manufactured by a co-extrusion method using a multilayer extruder. In addition, the single-layer sheets of each layer (for example, the first adhesive layer, the intermediate layer, and the second adhesive layer) constituting the high-frequency dielectric heating adhesive sheet of the present embodiment can be separately made, and the multiple single-layer sheets can be laminated to make them stacked, thereby manufacturing a multilayer structure sheet. When laminating the multiple single-layer sheets, for example, a heat laminator is used.

[0177] In addition, the high-frequency dielectric heating adhesive sheet of this embodiment can also be manufactured by hot extrusion coating or hot melt coating of applying a molten adhesive layer to a substrate, or by wet coating of a coating liquid obtained by dispersing or dissolving the adhesive layer composition in a solvent on a substrate.

[0178] When the adhesive for high-frequency dielectric heating of the present embodiment is a molded body, the production method is not particularly limited, and it can be produced, for example, as follows.

[0179] When the molded product of the present embodiment is a molded product composed of a single part obtained by molding the adhesive for high-frequency dielectric heating (first material), it can be produced by a single-color molding method.

[0180] The molded body of this embodiment is Figure 3A to Figure 3C In the case of a multi-color molded body having multiple parts such as the molded body shown in the figure, it can be manufactured by using multiple materials (for example, the first material and the second material) by a multi-color molding method. In addition, a molded body consisting of a single part obtained by molding the high-frequency dielectric heating adhesive (first material) can be embedded in another molded body to manufacture a multi-color molded body.

[0181] Furthermore, a multi-color molded body can be manufactured by insert molding using a first molded body formed of one of the first material and the second material and the other of the first material and the second material.

[0182] For example, when the second material is made of metal or ceramic, the molded body of this embodiment can be manufactured by preparing a second portion made of metal or ceramic in a desired shape in advance and insert molding the second portion and the first material.

[0183] In addition, for example, the molded body of this embodiment can be manufactured by using one of the first material and the second material to form a first molded body by injection molding or compression molding, and using the other of the first material and the second material and the first molded body by insert molding.

[0184] For example, the first molded body may be molded by injection molding or compression molding using the second material, and the first molded body may correspond to the second portion, and then the molded body may be manufactured by insert molding using the first material and the first molded body. The portion made of the first material formed by insert molding corresponds to the first portion.

[0185] (How to use the adhesive for high-frequency dielectric heating)

[0186] The high-frequency dielectric heating adhesive of this embodiment can be used for bonding to an adherend. In addition, the high-frequency dielectric heating adhesive of this embodiment can also be used for bonding a plurality of adherends to each other.

[0187] The material of the adherend is not particularly limited and may be any material of an organic material or an inorganic material (including a metal material, etc.), or may be a composite material of an organic material and an inorganic material.

[0188] 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, 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, etc. As rubber materials, styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPR), and silicone rubber, etc. can be cited. In addition, the adherend can also be a foaming material of an organic material.

[0189] Inorganic materials as the material of the adherend include glass materials, cement materials, ceramic materials, and metal materials. In addition, the adherend can also be a fiber reinforced resin (Fiber Reinforced Plastics, FRP) as a composite material of fiber and the above-mentioned plastic material. The plastic material in the fiber reinforced resin is, for example, at least one selected from the group consisting of 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 includes, for example, glass fiber, Kevlar fiber, and carbon fiber.

[0190] When a plurality of adherends are bonded to each other using the adhesive for high-frequency dielectric heating of the present embodiment, the plurality of adherends may be made of the same material or different materials.

[0191] The high-frequency dielectric heating adhesive of this embodiment can be suitably used for bonding to glass adherends. When bonding multiple adherends, if at least one of the adherends is made of glass, the high-frequency dielectric heating adhesive of this embodiment can be strongly bonded to the glass adherend.

[0192] The shape of the adherend is not particularly limited, but preferably has a surface to which the high-frequency dielectric heating adhesive can be attached, and is preferably in the form of a sheet or plate. When multiple adherends are bonded to each other, the shapes and sizes of these adherends may be the same or different.

[0193] [Bonding method]

[0194] The bonding method of the present embodiment is a bonding method using the adhesive for high-frequency dielectric heating of the present embodiment.

[0195] Hereinafter, as an example of the bonding method of this embodiment, a method of bonding the first adherend and the second adherend using a high-frequency dielectric heating adhesive sheet composed of a single adhesive layer is described, but the present invention is not limited to this method. The material of the second adherend is not particularly limited.

[0196] The bonding method according to one aspect of the present embodiment includes the following steps P1 and P2.

[0197] Process P1

[0198] Step P1 is a step of sandwiching the high-frequency dielectric heating adhesive sheet of this embodiment between a first adherend and a second adherend. In step P1, the first adherend made of glass is brought into contact with the first surface of the high-frequency dielectric heating adhesive sheet. In addition, in step P1, the second adherend is brought into contact with the second surface of the high-frequency dielectric heating adhesive sheet.

[0199] The high-frequency dielectric heating adhesive sheet can be sandwiched between the first adherend and the second adherend in a manner that can bond the first adherend to the second adherend. The high-frequency dielectric heating adhesive sheet can be sandwiched between a portion, multiple portions or the entire surface of the first adherend and the second adherend. From the viewpoint of improving the bonding strength between the first adherend and the second adherend, it is preferred to sandwich the high-frequency dielectric heating adhesive sheet with the entire bonding surface of the first adherend and the second adherend. In addition, as a method of sandwiching the high-frequency dielectric heating adhesive sheet between the first adherend and the second adherend, a method of configuring the high-frequency dielectric heating adhesive sheet in a frame shape and sandwiching it between the first adherend and the second adherend along the periphery of the bonding surface of the first adherend and the second adherend can be cited. By configuring the high-frequency dielectric heating adhesive sheet in a frame shape like this, the bonding strength between the first adherend and the second adherend can be obtained, and the joint body can be made lighter than the case where the high-frequency dielectric heating adhesive sheet is configured on the entire bonding surface. In addition, by utilizing a method in which a portion of the high-frequency dielectric heating adhesive sheet is sandwiched between the first adherend and the second adherend, the size of the high-frequency dielectric heating adhesive sheet used can be reduced. Therefore, the high-frequency dielectric heating treatment time can be shortened compared to a case in which the high-frequency dielectric heating adhesive sheet is arranged on the entire bonding surface.

[0200] Process P2

[0201] Step P2 is a step of applying a high frequency electric field of 3 MHz to 300 MHz to the high frequency dielectric heating adhesive sheet interposed between the first adherend and the second adherend in step P1 to bond the first adherend and the second adherend using the high frequency dielectric heating adhesive sheet.

[0202] For example, a high-frequency electric field can be applied to the high-frequency dielectric heating adhesive sheet by using a dielectric heating bonding device. It should be noted that in this specification, a "dielectric heating device" may be referred to as a "dielectric heating bonding device" or a "high-frequency dielectric heating device".

[0203] Figure 2 A schematic diagram for explaining a high-frequency dielectric heating process using the high-frequency dielectric heating adhesive sheet and the dielectric heating device according to the present embodiment is shown.

[0204] (Dielectric heating bonding device)

[0205] Figure 2 A schematic diagram of a dielectric heating bonding device 50 is shown.

[0206] The dielectric heating bonding device 50 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 .

[0207] 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, the first adherend 110, the high-frequency dielectric heating adhesive sheet 1A and the second adherend 120 can be pressurized between the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52.

[0208] 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.

[0209] The application of the high-frequency electric field is also preferably performed 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 sheet located between the electrodes, thereby being able to heat the entire high-frequency dielectric heating adhesive sheet, and the adherend and the high-frequency dielectric heating adhesive sheet can be bonded in a short time.

[0210] A high frequency power source 53 for applying a high frequency electric field with a frequency of 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 .

[0211] like Figure 2 As shown, the dielectric heating bonding device 50 performs dielectric heating treatment by means of the high-frequency dielectric heating adhesive sheet 1A sandwiched between the first adherend 110 and the second adherend 120. In addition, in addition to the dielectric heating treatment, the dielectric heating bonding device 50 also bonds the first adherend 110 and the second adherend 120 by a pressure 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 the first adherend 110 and the second adherend 120 may be bonded together by, for example, pressing based on the self-weight of the adhesive sheet and the adherends without performing the pressure treatment. It should be noted that the first adherend 110 and the second adherend 120 may be bonded together without performing the pressure treatment.

[0212] 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 , a dielectric filler (not shown) dispersed in the adhesive component of the high-frequency dielectric heating adhesive sheet 1A absorbs high-frequency energy.

[0213] The dielectric filler functions as a heat source, and the heat generated by the dielectric filler melts the thermoplastic resin component, so that the first adherend 110 and the second adherend 120 can be firmly bonded together even in a short treatment time.

[0214] 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 sheet 1A, a stronger bonding between the first adherend 110 and the second adherend 120 can be achieved.

[0215] (High frequency dielectric heating bonding conditions)

[0216] The high-frequency dielectric heating bonding conditions can be changed appropriately, but are preferably the following conditions.

[0217] 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.

[0218] 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.

[0219] 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, so that good adhesive strength is easily obtained.

[0220] 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.

[0221] The high-frequency electric field is preferably applied for a time period of 1 second or longer.

[0222] 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, and further preferably 100 seconds or less.

[0223] 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.

[0224] 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 joined body formed by bonding the first adherend and the second adherend, an increase in the manufacturing cost, and thermal degradation of the adherends.

[0225] The frequency of the high-frequency electric field to be applied is preferably 1 kHz or higher, more preferably 1 MHz or higher, further preferably 5 MHz or higher, and further preferably 10 MHz or higher.

[0226] 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, and 40.68 MHz allocated by the International Telecommunication Union can also be used for the high-frequency dielectric heating bonding method (bonding method) of this embodiment.

[0227] (Effects of this embodiment)

[0228] The high-frequency dielectric heating adhesive of this embodiment can bond to glass with high bonding strength even with low energy consumption. Furthermore, the high-frequency dielectric heating adhesive of this embodiment is an adhesive that is less likely to decrease in bonding strength over time and has excellent long-term storage properties.

[0229] The adhesive for high-frequency dielectric heating according to the present embodiment is superior in water resistance and moisture resistance compared to general adhesives.

[0230] The high-frequency dielectric heating adhesive of this embodiment can be heated by applying a high-frequency electric field, so the high-frequency dielectric heating adhesive is locally heated. Therefore, the high-frequency dielectric heating adhesive of this embodiment can easily prevent the entire adherend from melting when bonding to the adherend.

[0231] According to the bonding method using the high-frequency dielectric heating adhesive of the present embodiment, it is possible to locally heat only a given portion from the outside using a dielectric heating bonding 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 bonding method using the high-frequency dielectric heating adhesive of the present embodiment is effective.

[0232] [Variations of Embodiments]

[0233] 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.

[0234] The high-frequency dielectric heating adhesive sheet may have an adhesive portion. By having an adhesive portion, when the high-frequency dielectric heating adhesive sheet is sandwiched between the adherends, positional displacement can be prevented and the sheet can be configured at an accurate position. The adhesive portion may be provided on one side of the high-frequency dielectric heating adhesive sheet or on both sides. In addition, the adhesive portion may also be provided locally relative to the surface of the high-frequency dielectric heating adhesive sheet. Even in the case where the high-frequency dielectric heating adhesive sheet does not have an adhesive portion, the first adherend and the second adherend can be firmly bonded.

[0235] The high-frequency dielectric heating treatment is not limited to the dielectric heating bonding 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 at regular intervals on the same plane.

[0236] For example, when manufacturing a bonded body in which the ends of a first adherend and a second adherend are overlapped and bonded, a grid electrode type high-frequency dielectric heating device is arranged on the first adherend side or the second adherend side to apply a high-frequency electric field.

[0237] When a grid electrode type high-frequency dielectric heating device is used to bond a first adherend to a second adherend, a first grid electrode can be arranged on the first adherend side and a second grid electrode can be arranged on the second adherend side, so that the first adherend, the high-frequency dielectric heating adhesive and the second adherend are sandwiched between the first grid electrode and the second grid electrode and a high-frequency electric field is applied simultaneously.

[0238] When a grid electrode type high-frequency dielectric heating device is used to bond a first adherend to a second adherend, a grid electrode can be arranged on the surface side of one of the first adherend and the second adherend and a high-frequency electric field can be applied, and then a grid electrode can be arranged on the surface side of the other of the first adherend and the second adherend and a high-frequency electric field can be applied.

[0239] The high-frequency electric field is preferably applied using a grid electrode type high-frequency dielectric heating device. By using a grid electrode type high-frequency dielectric heating device, the adherends can be bonded to each other by performing dielectric heating from the surface side of the first adherend and the second adherend, for example, from the side of the adherend that is close to the high-frequency dielectric heating adhesive, without being affected by the thickness of the first adherend and the second adherend. In addition, by using a grid electrode type high-frequency dielectric heating device, energy saving can be achieved in the manufacture of the joint body.

[0240] It should be noted that, for the sake of simplicity, the drawings illustrate an example of a method using a dielectric heating bonding device in which electrodes are arranged to face each other.

[0241] Example

[0242] 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.

[0243] [Manufacturing of adhesive for high-frequency dielectric heating]

[0244] (Examples 1 to 5 and Comparative Examples 1 to 2)

[0245] The materials shown in Table 1 were premixed. The premixed materials were supplied to the hopper of a 30 mm φ twin-screw extruder, the barrel setting temperature was set to 180°C or higher and 200°C or lower, and the die temperature was set to 200°C, and the premixed materials were melt-kneaded. The melt-kneaded material was cooled, and then the material was cut to produce granular pellets. Next, the produced granular pellets were put into the hopper of a single screw extruder equipped with a T-die, and the barrel temperature was set to 200°C and the die temperature was set to 200°C. A film-like molten kneaded material was extruded from the T-die, and cooled using a cooling roller, thereby producing sheet-like high-frequency dielectric heating adhesives (high-frequency dielectric heating adhesive sheets) with a thickness of 400 μm of Examples 1 to 5 and Comparative Examples 1 to 2, respectively.

[0246] The thermoplastic resins and fillers shown in Table 1 are described below.

[0247] Silane-modified PP: Silane-modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "LINKLON PM700N"

[0248] Silane-modified PE: Silane-modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "LINKLON SS732N"

[0249] ·m-PP: Maleic anhydride-modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "MODIC P565"

[0250] PP: Polypropylene, manufactured by Prime Polymer Co., Ltd., product name: "Prime Polypro F-744NP"

[0251] ·m-PE: Maleic anhydride-modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "MODIC M545"

[0252] Zinc oxide (ZnO): Zinc oxide having a volume average particle size of 11 μm. Made by Sakai Chemical Industry Co., Ltd., product name “LP-ZINC11”

[0253] (MFR: Melt Flow Rate)

[0254] The MFR of the thermoplastic resin at 190° C. was measured based on JIS K 7210-1:2014 using a falling flow tester (manufactured by Shimadzu Corporation, model “CFT-100D”).

[0255] When a plurality of thermoplastic resins were used in mixture, the plurality of resins were twin-screw kneaded at the ratio shown in Table 1 to prepare mixed resin pellets, and the MFR of the mixed resin pellets was measured in the same manner as above.

[0256] (Volume average particle size of dielectric filler)

[0257] The particle size distribution of the dielectric filler was measured by a laser diffraction / scattering method. The volume average particle size was calculated based on the results of the particle size distribution measurement in accordance with JIS Z 8819-2: 2001. The calculated volume average particle size of zinc oxide (ZnO) was 11 μm.

[0258] [Evaluation of high frequency dielectric heating adhesive sheets]

[0259] The high-frequency dielectric heating adhesive sheet was evaluated as follows. The evaluation results are shown in Table 1.

[0260] (Adhesion strength (tensile shear strength))

[0261] Adhesion strength (tensile shear force) was evaluated as one index for evaluating high-frequency adhesion.

[0262] The produced high-frequency dielectric heating adhesive sheet was cut into a size of 25mm×12.5mm. The cut high-frequency dielectric heating adhesive sheet was arranged between soda-lime glass (25mm×100mm×3mm (thickness)) as a pair of adherends (the first adherend and the second adherend) in a manner consistent with the overlapping portion of the adherends. After such an arrangement, a pair of adherends and the high-frequency dielectric heating adhesive sheet were fixed between the electrodes of a high-frequency dielectric heating device (manufactured by Yamamoto Vinita Co., Ltd., product name "YRP-400T-A"). The area of ​​a pair of electrodes of the high-frequency dielectric heating device is set to 800mm respectively. 2 The pair of electrodes were arranged to cover the overlapping portion of the adherend (soda lime glass) (=40 mm×20 mm). 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, and a test piece for evaluating the adhesive strength was prepared.

[0263] The prepared high-frequency dielectric heating adhesive sheet was separately stored under high temperature and high humidity conditions for a long period of time (stored at 50° C. and 95% RH for 1 week), and then a test piece for evaluating adhesive strength was prepared in the same manner as above.

[0264] ·High frequency application conditions

[0265] Frequency: 40.68MHz

[0266] Output power: 150W

[0267] Application time: 20 seconds

[0268] Pressing pressure: 0.5MPa

[0269] The pressing force during high frequency application is a pressure applied to the bonding portion between the first adherend and the second adherend.

[0270] The test piece made of the high-frequency dielectric heating adhesive sheet before long-term storage under high temperature and high humidity conditions was used as the test piece before the promotion test, and the test piece made of the high-frequency dielectric heating adhesive sheet after long-term storage was used as the test piece after the promotion test. The tensile shear force (unit: MPa) as the bonding force was measured using these test pieces. The tensile shear force was measured using a universal tensile testing machine (Instron company, product name "Instron5581"). The tensile speed in the measurement of the tensile shear force was set to 10mm / min. It should be noted that ">4.0" in the table indicates that the tensile shear force exceeds 4.0MPa. The tensile shear force was measured based on JIS K 6850:1999.

[0271]

[0272] Since the high-frequency dielectric heating adhesive sheets of Examples 1 to 5 contain silane-modified thermoplastic resins and non-silane-modified thermoplastic resins as thermoplastic resins, they can join glass adherends to each other with high bonding strength with very little energy consumption. The tensile shear force before the promotion test is high and the tensile shear force after the promotion test is also above the same level. The adhesive strength does not decrease over time and the long-term storage property is high.

[0273] Since the high-frequency dielectric heating adhesive sheet of Comparative Example 1 contains a silane-modified thermoplastic resin as a thermoplastic resin, the tensile shear force before the promotion test is high. However, the high-frequency dielectric heating adhesive sheet of Comparative Example 1 does not contain a thermoplastic resin that is not modified by silane, and the tensile shear force after the promotion test is greatly reduced. As such, the high-frequency dielectric heating adhesive sheet of Comparative Example 1 is an adhesive sheet whose adhesive force is easily reduced over time and has low long-term storage properties.

[0274] The high-frequency dielectric heating adhesive sheet of Comparative Example 2 did not contain a silane-modified thermoplastic resin as a thermoplastic resin, and therefore did not adhere to glass.

Claims

1. An adhesive for high-frequency dielectric heating, comprising at least a thermoplastic resin (A) and a dielectric material that generates heat by applying a high-frequency electric field, The thermoplastic resin (A) includes at least a first thermoplastic resin (A1) and a second thermoplastic resin (A2), The first thermoplastic resin (A1) is a silane-modified thermoplastic resin, The second thermoplastic resin (A2) is a thermoplastic resin that is not modified with silane, The second thermoplastic resin (A2) has a polar part.

2. The adhesive for high-frequency dielectric heating according to claim 1, wherein: The polar part of the second thermoplastic resin (A2) is an acidic part.

3. The adhesive for high-frequency dielectric heating according to claim 2, wherein: The polar part of the second thermoplastic resin (A2) is an acid anhydride structure.

4. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The first thermoplastic resin (A1) is a silane-modified polyolefin resin.

5. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The second thermoplastic resin (A2) is a polyolefin resin that is not modified with silane.

6. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The first thermoplastic resin (A1) is mainly composed of ethylene or propylene.

7. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The second thermoplastic resin (A2) is mainly composed of ethylene or propylene.

8. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The main composition of the first thermoplastic resin (A1) is the same as the main composition of the second thermoplastic resin (A2).

9. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The volume content of the first thermoplastic resin (A1) in the thermoplastic resin (A) contained in the adhesive for high-frequency dielectric heating is 15 volume % or more and 80 volume % or less.

10. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The thermoplastic resin (A) has an MFR at 190° C. of 2 g / 10 min or more and 50 g / 10 min or less.

11. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The volume content of the dielectric material in the high-frequency dielectric heating adhesive is 5 volume % or more and 50 volume % or less.

12. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The dielectric material is a dielectric filler (B).

13. The adhesive for high-frequency dielectric heating according to claim 12, wherein: The dielectric filler (B) includes at least one selected from zinc oxide, silicon carbide, barium titanate, and titanium oxide.

14. The adhesive for high-frequency dielectric heating according to claim 12, wherein: The volume average particle size of the dielectric filler (B) is 1 μm or more and 30 μm or less, The volume average particle size is a volume average particle size calculated based on the particle size distribution measurement results of the dielectric filler (B) by a laser diffraction / scattering method and in accordance with JIS Z 8819-2:2001.

15. The adhesive for high-frequency dielectric heating according to any one of claims 1 to 3, wherein The adhesive for high-frequency dielectric heating is an adhesive sheet.

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