High frequency dielectric heating adhesive sheet

Abstract

A high-frequency dielectric heating adhesive sheet (1A) having an adhesive layer (10) containing at least a thermoplastic resin (A) and a dielectric material that generates heat due to the application of a high-frequency electric field, wherein: the adhesive layer (10) contains a silane-modified polyolefin as the thermoplastic resin (A); and the MFR of the thermoplastic resin (A) at 190°C is 2-50 g / 10 min, inclusive.

Description

[Technical Field]

[0001] The present invention relates to a high frequency dielectric heating adhesive sheet. [Background technology]

[0002] In recent years, methods have been proposed for bonding adherends that are generally difficult to bond together, such as by interposing an adhesive made of a specific resin blended with a heat-generating material between the adherends and performing dielectric heating treatment, induction heating treatment, ultrasonic welding treatment, laser welding treatment, or the like. When glass is used as the adherend, the following techniques are available as adhesion methods.

[0003] For example, Patent Document 1 describes a thermoplastic resin composition for bonding glass and inorganic reinforced thermoplastic resin, which contains a heating element that generates heat by high-frequency induction and a thermoplastic resin with a melting point of 90°C to 200°C that has been modified with a monomer containing a functional group that reacts with inorganic matter in the presence of moisture.

[0004] For example, Patent Document 2 describes a dielectric heating adhesive film for adhering multiple adherends made of the same or different materials, and this dielectric heating adhesive film contains a polyolefin resin having polar moieties and a dielectric filler blended in a predetermined ratio.

[0005] As another bonding method, for example, Patent Document 3 describes a glass adhesion sheet for adhering to a glass surface by a vacuum lamination method, and this glass adhesion sheet contains a silane-modified polyethylene resin obtained by graft-polymerizing an ethylenically unsaturated silane compound to low-density polyethylene. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-097445 [Patent Document 2] International Publication No. 2018 / 147352 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-068426 Summary of the Invention [Problem to be solved by the invention]

[0007] When the thermoplastic resin composition described in Patent Document 1 is used, a large amount of energy is consumed to bond to glass, and when the glass-adhering sheet described in Patent Document 3 is used, the pressure holding time during vacuum lamination required for bonding to glass is long. Patent Document 2 also describes a glass material as an example of an adherend, but the dielectric heating adhesive film described in Patent Document 2 does not easily achieve sufficient adhesive strength to glass materials.

[0008] An object of the present invention is to provide a high-frequency dielectric heating adhesive sheet that can be bonded to glass with high adhesive strength even with little energy consumption. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a high-frequency dielectric heating adhesive sheet having an adhesive layer containing at least a thermoplastic resin (A) and a dielectric material that generates heat upon application of a high-frequency electric field, The adhesive layer contains a silane-modified polyolefin as the thermoplastic resin (A), The thermoplastic resin (A) has an MFR at 190°C of 2 g / 10 min or more and 50 g / 10 min or less, thereby providing a high-frequency dielectric heating adhesive sheet.

[0010] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the softening temperature of the high-frequency dielectric heating adhesive sheet is preferably 50°C or higher.

[0011] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the high-frequency dielectric heating adhesive sheet preferably has a storage modulus at 20° C. of 5 MPa or more.

[0012] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the loss tangent peak temperature of the high-frequency dielectric heating adhesive sheet is preferably 30°C or less.

[0013] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the volume content of the dielectric material in the adhesive layer is preferably 5% by volume or more and 50% by volume or less.

[0014] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the dielectric material is preferably a dielectric filler (B).

[0015] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the dielectric filler (B) preferably contains at least one selected from the group consisting of zinc oxide, silicon carbide, barium titanate, and titanium oxide.

[0016] In the high-frequency dielectric heating adhesive sheet according to one embodiment of the present invention, it is preferable that the volume average particle diameter of the dielectric filler (B) is 1 μm or more and 30 μm or less, and that the volume average particle diameter is determined by measuring the particle size distribution of the dielectric filler (B) by a laser diffraction / scattering method and calculating the volume average particle diameter from the results of the particle size distribution measurement in accordance with JIS Z 8819-2:2001.

[0017] In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the high-frequency dielectric heating adhesive sheet preferably has a thickness of 5 μm or more.

[0018] According to one aspect of the present invention, it is possible to provide a high-frequency dielectric heating adhesive sheet that can be bonded to glass with high adhesive strength even with low energy consumption. [Brief explanation of the drawings]

[0019] [Figure 1A] 1 is a schematic cross-sectional view of a high-frequency dielectric heating adhesive sheet according to one embodiment. FIG. [Figure 1B]1 is a schematic cross-sectional view of a high-frequency dielectric heating adhesive sheet according to one embodiment. FIG. [Figure 1C] 1 is a schematic cross-sectional view of a high-frequency dielectric heating adhesive sheet according to one embodiment. FIG. [Figure 2] FIG. 1 is a schematic diagram illustrating a high-frequency dielectric heating process using a high-frequency dielectric heating adhesive sheet and a dielectric heating device according to one embodiment. [Figure 3A] FIG. 10 is a diagram for explaining evaluation of the wetting and spreading properties of a sheet. [Figure 3B] FIG. 10 is a diagram for explaining evaluation of the wetting and spreading properties of a sheet. [Figure 3C] FIG. 10 is a diagram for explaining evaluation of the wetting and spreading properties of a sheet. DETAILED DESCRIPTION OF THE INVENTION

[0020] [High frequency dielectric heating adhesive sheet] The high-frequency dielectric heating adhesive sheet according to this embodiment has an adhesive layer containing at least a thermoplastic resin (A) and a dielectric material that generates heat when a high-frequency electric field is applied. The adhesive layer contains a silane-modified polyolefin as the thermoplastic resin (A), and the MFR of the thermoplastic resin (A) at 190°C is 2 g / 10 min or more and 50 g / 10 min or less. The high-frequency electric field is an electric field whose direction is reversed at high frequencies.

[0021] The dielectric material is a material that generates heat when a high-frequency electric field is applied, and is preferably a material that generates heat when a high-frequency electric field in the 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. From the viewpoint of easily suppressing deterioration of the dielectric material contained in the high-frequency dielectric heating adhesive sheet when the high-frequency dielectric heating adhesive sheet is processed, the dielectric material is more preferably a dielectric filler (B). Hereinafter, a case where the high-frequency dielectric heating adhesive sheet according to this embodiment contains a dielectric filler (B) as the dielectric material will be described.

[0022] <Thermoplastic resin (A)> The adhesive layer contains one or more types of thermoplastic resin (A), and contains at least a silane-modified polyolefin as the thermoplastic resin (A).

[0023] (MFR of thermoplastic resin) The MFR of the thermoplastic resin (A) at 190° C. is 2 g / 10 min or more, preferably 2.5 g / 10 min or more, and more preferably 3 g / 10 min or more. The MFR of the thermoplastic resin (A) at 190° C. is 50 g / 10 min or less, preferably 30 g / 10 min or less, and more preferably 20 g / 10 min or less. When the thermoplastic resin (A) has an MFR of 2 g / 10 min or more at 190° C., the sheet formability is excellent, and the adhesive layer wets and spreads well during bonding, making it easy to obtain bonding strength in a short time. By ensuring that the MFR of the thermoplastic resin (A) at 190°C is 50 g / 10 min or less, it is easy to prevent the viscosity of the adhesive layer from becoming too low during dielectric heat treatment. If the viscosity of the adhesive layer becomes too low, the amount of resin between the adherends decreases during bonding, making it difficult to obtain adhesive strength. However, by preventing a decrease in viscosity, it is easier to obtain adhesive strength. When the adhesive layer contains only a silane-modified polyolefin as the thermoplastic resin (A), the MFR of the silane-modified polyolefin at 190°C satisfies the above-mentioned range of MFR at 190°C of the thermoplastic resin (A). Furthermore, when the thermoplastic resin (A) in the adhesive layer is a mixture containing not only silane-modified polyolefin but also other thermoplastic resins, the MFR at 190°C of the thermoplastic resin mixture in the adhesive layer satisfies the above-mentioned range of MFR at 190°C of the thermoplastic resin (A). The MFR of the thermoplastic resin (A) at 190°C can be measured by the method described in the Examples section below.

[0024] (Silane-modified polyolefin) The silane-modified polyolefin is not particularly limited, but is preferably at least one selected from the group consisting of a copolymer of a silyl group-containing compound and an olefin, and a silane-modified polyolefin obtained by graft polymerizing a polyolefin with a silyl group-containing compound.

[0025] 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 at least one olefin selected from the group consisting of 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 the group consisting of ethylene and propylene. The olefin copolymerized with the silyl group-containing compound may be one type or two or more types. The polyolefin to be graft polymerized with a silyl group-containing compound includes a homopolymer of the above olefin and a copolymer of two or more olefins, and a homopolymer or copolymer having a monomer unit derived from at least one of ethylene and propylene is preferred. Also preferred is a silane-modified polyolefin obtained by graft polymerizing a polyolefin having a reactive group in advance with a silyl group-containing compound.

[0026] Examples of silyl group-containing compounds include vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, vinyltricarboxysilane, vinyltriacetylsilane, vinyltrichlorosilane, vinyltrismethylethylketoximesilane, vinyltriisopropenoxysilane, and vinylmethyldimethoxysilane; (meth)acrylic silanes such as (meth)acryloxymethyltrimethoxysilane; and styryl silanes such as styryltrimethoxysilane. In this specification, "(meth)acrylic" is a term used to refer to both "acrylic" and "methacrylic", and the same applies to other similar terms.

[0027] (Other thermoplastic resins) The adhesive layer may contain a thermoplastic resin other than the silane-modified polyolefin, and the type of the other thermoplastic resin is not particularly limited, as long as the object of the present invention can be achieved. When the adhesive layer contains a mixture of a silane-modified polyolefin and another thermoplastic resin as the thermoplastic resin, the viscosity of the adhesive layer can be easily adjusted, the high-frequency dielectric heating adhesive sheet can be easily made processable, and unintended crosslinking reactions can be suppressed, which helps prevent deterioration of adhesive strength over time. When the adhesive layer contains a silane-modified polyolefin as the main component of the thermoplastic resin, the adhesive layer is likely to have high adhesive strength to glass.

[0028] When the adhesive layer contains a silane-modified polyolefin and another thermoplastic resin, the content of the silane-modified polyolefin in the thermoplastic resin (A) in the adhesive layer is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 40% by volume or more. Also, the content of the silane-modified polyolefin in the thermoplastic resin (A) in the adhesive layer is preferably 100% by volume or less.

[0029] The other thermoplastic resin is preferably at least one selected from the group consisting of polyolefin-based resins, styrene-based resins, polyacetal-based resins, polycarbonate-based resins, poly(meth)acrylic-based resins, polyamide-based resins, polyimide-based resins, polyvinyl acetate-based resins, phenoxy-based resins, and polyester-based resins, for example, from the viewpoint of being easily meltable and having a predetermined heat resistance.

[0030] In this specification, the polyolefin resins referred to as "other thermoplastic resins" include polyolefin resins having polar moieties and polyolefin resins not having polar moieties, and are resins different from silane-modified polyolefins. When specifying whether or not a polyolefin resin has polar moieties, it is described as a polyolefin resin having polar moieties or a polyolefin resin not having polar moieties.

[0031] The adhesive layer preferably further contains a polyolefin resin having a polar moiety as the thermoplastic resin (A), and the polyolefin resin having a polar moiety is preferably an acid-modified polyolefin resin. When the adhesive layer contains a silane-modified polyolefin and a polyolefin-based resin having a polar moiety, the volume ratio of the silane-modified polyolefin to the polyolefin-based resin having a polar moiety in the adhesive layer is preferably 10:90 to 90:10, more preferably 20:80 to 85:15, and even more preferably 30:70 to 80:20.

[0032] (Polyolefin resin) When the adhesive layer contains a polyolefin resin as the thermoplastic resin (A), examples of the polyolefin resin include resins made of homopolymers such as polyethylene, polypropylene, polybutene, and polymethylpentene, and α-olefin resins made of copolymers of monomers selected from the group consisting of ethylene, propylene, butene, hexene, octene, and 4-methylpentene. The polyolefin resin as the thermoplastic resin (A) may be a single resin or a combination of two or more resins.

[0033] (Polyolefin resin with polar moieties) The polar moiety in the polyolefin resin having a polar moiety is not particularly limited as long as it is a moiety that can impart polarity to the polyolefin resin. Polyolefin resins having a polar moiety are preferred because they exhibit high adhesive strength to adherends. The polyolefin resin having a polar moiety may be a copolymer of an olefin monomer and a monomer having a polar moiety, or may be a resin obtained by introducing a polar moiety into an olefin polymer obtained by polymerization of an olefin monomer by modification such as an addition reaction.

[0034] The type of olefinic monomer constituting the polyolefinic resin having a polar moiety is not particularly limited. Examples of the olefinic monomer include ethylene, propylene, butene, hexene, octene, and 4-methyl-1-pentene. The olefinic monomer may be used alone or in combination of two or more. The olefin-based monomer is preferably at least one of ethylene and propylene, from the viewpoint of excellent mechanical strength and stable adhesive properties. The olefin-derived structural unit in the polyolefin-based resin having a polar moiety is preferably a structural unit derived from ethylene or propylene.

[0035] Examples of the polar moiety include a hydroxyl group, a carboxyl group, an epoxy group, a vinyl acetate structure, an acid anhydride structure, etc. Examples of the polar moiety also include an acid-modified structure that is introduced into a polyolefin resin by acid modification.

[0036] The acid-modified structure as a polar moiety is a moiety introduced by acid-modifying a thermoplastic resin (e.g., a polyolefin-based resin). Compounds used to acid-modify a thermoplastic resin (e.g., a polyolefin-based resin) include unsaturated carboxylic acid derivative components derived from unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, and esters of unsaturated carboxylic acids. In this specification, a polyolefin-based resin having an acid-modified structure may be referred to as an acid-modified polyolefin-based resin.

[0037] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0038] Examples of the acid anhydrides of unsaturated carboxylic acids include acid anhydrides of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, and citraconic anhydride.

[0039] Examples of the esters of unsaturated carboxylic acids include esters of unsaturated carboxylic acids such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl itaconate, diethyl itaconate, dimethyl citraconate, diethyl citraconate, and dimethyl tetrahydrophthalic anhydride.

[0040] When the polyolefin resin as thermoplastic resin (A) is a copolymer of an olefin monomer and a monomer having a polar moiety, the copolymer preferably contains 2% by mass or more, more preferably 4% by mass or more, even more preferably 5% by mass or more, and even more preferably 6% by mass or more of structural units derived from the monomer having a polar moiety. The copolymer preferably contains 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 15% by mass or less of structural units derived from the monomer having a polar moiety. When the copolymer contains 2% by mass or more of structural units derived from monomers having polar moieties, the adhesive strength of the high-frequency dielectric heating adhesive sheet is improved. Furthermore, when the copolymer contains 30% by mass or less of structural units derived from monomers having polar moieties, the tackiness of the thermoplastic resin (A) can be prevented from becoming too strong. As a result, it becomes easier to prevent difficulties in molding the high-frequency dielectric heating adhesive sheet.

[0041] When the polyolefin resin as the thermoplastic resin (A) 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 even more preferably 0.2% by mass or more. When the polyolefin resin as the thermoplastic resin (A) 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 even more preferably 10% by mass or less. When the thermoplastic resin (A) has an acid-modified structure, the acid modification rate of 0.01% by mass or more improves the adhesive strength of the high-frequency dielectric heating adhesive sheet. Furthermore, the acid modification rate of 30% by mass or less prevents the thermoplastic resin (A) from becoming too tacky. As a result, it becomes easier to prevent difficulties in molding the high-frequency dielectric heating adhesive sheet. In this specification, the degree of modification by acid is the percentage of the mass of the portion derived from the acid relative to the total mass of the acid-modified polyolefin.

[0042] (Maleic anhydride modified polyolefin) The polyolefin resin as the thermoplastic resin (A) preferably has an acid anhydride structure as the acid-modified structure. The acid anhydride structure is more preferably a maleic anhydride structure. The maleic anhydride structure may be a group introduced by graft-modifying a thermoplastic resin, or may be a maleic anhydride copolymer obtained by copolymerizing a monomer containing a maleic anhydride structure. In the maleic anhydride-modified polyolefin, the modification rate with maleic anhydride is preferably in the same range as the modification rate when the polyolefin resin as the thermoplastic resin (A) has an acid-modified structure, and the effects obtained by being in this range are also the same as when the polyolefin resin as the thermoplastic resin (A) has an acid-modified structure. When the maleic anhydride-modified polyolefin is a copolymer of an olefinic monomer and a monomer containing a maleic anhydride structure, the proportion of the constituent units derived from the monomer containing a maleic anhydride structure in the copolymer is preferably in the same range as the proportion of the constituent units derived from the monomer containing a polar moiety in the copolymer of an olefinic monomer and a monomer containing a polar moiety, and the effects obtained by being within this range are the same as when the polyolefin resin as the thermoplastic resin (A) is a copolymer of an olefinic monomer and a monomer containing a polar moiety.

[0043] The olefin-derived structural units in the maleic anhydride-modified polyolefin are preferably structural units derived from ethylene or propylene, i.e., the maleic anhydride-modified polyolefin is preferably a maleic anhydride-modified polyethylene resin or a maleic anhydride-modified polypropylene resin.

[0044] When the adhesive layer contains a silane-modified polyolefin as the thermoplastic resin (A) and an acid-modified resin as the other thermoplastic resin, the acid-modified resin also has good adhesion to glass, so even if the proportion of silane-modified polyolefin in the adhesive layer decreases, it is easy to suppress a decrease in adhesive strength. When the adhesive layer contains a silane-modified polyolefin and an acid-modified resin as the thermoplastic resin (A), the total volume content of the silane-modified polyolefin and the acid-modified resin in the thermoplastic resin (A) is preferably 80% by volume or more, more preferably 90% by volume or more, and even more preferably 99% by volume or more.

[0045] <Dielectric filler (B)> The dielectric filler (B) is a filler that generates heat when a high-frequency electric field 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 or more and 300 MHz or less is applied to it. The dielectric filler (B) is preferably a filler that generates heat when a high-frequency electric field in the frequency range of 3 MHz or more and 300 MHz or less is applied to it, for example, a frequency of 13.56 MHz, 27.12 MHz, or 40.68 MHz.

[0046] (kinds) The dielectric filler (B) is preferably an inorganic material having crystal water such as zinc oxide, silicon carbide (SiC), anatase type titanium oxide, barium titanate, barium titanate zirconate, lead titanate, potassium niobate, rutile type titanium oxide, hydrated aluminum silicate, hydrated aluminosilicate of an alkali metal, or an inorganic material having crystal water such as hydrated aluminosilicate of an alkaline earth metal, either alone or in combination of two or more.

[0047] The dielectric filler (B) preferably contains at least one selected from the group consisting of zinc oxide, silicon carbide, barium titanate, and titanium oxide.

[0048] Among the dielectric fillers listed above, zinc oxide is more preferred as the dielectric filler (B) because it is available in a wide variety of shapes and sizes, allowing for the adhesive and mechanical properties of the high-frequency dielectric heating adhesive sheet to be improved to suit the application. By using zinc oxide as the dielectric filler (B), a colorless high-frequency dielectric heating adhesive sheet can be obtained. Because zinc oxide has a low density among dielectric fillers, when adherends are bonded using a high-frequency dielectric heating adhesive sheet containing zinc oxide as the dielectric filler (B), the total weight of the bonded body is less likely to increase compared to when sheets containing other dielectric fillers are used. Zinc oxide is not too hard for ceramics, so it is less likely to damage the manufacturing equipment for high-frequency dielectric heating adhesive sheets. Because zinc oxide is an inert oxide, it causes less damage to thermoplastic resins when blended with them. Furthermore, the titanium oxide as the dielectric filler (B) is preferably at least one of anatase type titanium oxide and rutile type titanium oxide, and from the viewpoint of excellent dielectric properties, anatase type titanium oxide is more preferable.

[0049] (volume content) The volume content of the dielectric filler (B) in the adhesive layer is preferably 5% by volume or more, more preferably 8% by volume or more, and even more preferably 10% by volume or more. The volume content of the dielectric filler (B) in the adhesive layer is preferably 50% by volume or less, more preferably 40% by volume or less, even more preferably 35% by volume or less, and even more preferably 25% by volume or less. When the volume content of the dielectric filler (B) in the adhesive layer is 5% by volume or more, heat generation is improved and it becomes easier to firmly bond the adhesive layer to the glass adherend. By keeping the volume content of the dielectric filler (B) in the adhesive layer at 50% by volume or less, it becomes easier to obtain flexibility as a sheet and to prevent a decrease in toughness, so that the high-frequency dielectric heating adhesive sheet can be easily processed into the desired shape in subsequent processes.

[0050] Since the high-frequency dielectric heating adhesive sheet according to this embodiment contains a thermoplastic resin (A) and a dielectric filler (B), the volume content of the dielectric filler (B) relative to the total volume of the thermoplastic resin (A) and the dielectric filler (B) is preferably 5% by volume or more, more preferably 8% by volume or more, and even more preferably 10% by volume or more. The volume content of the dielectric filler (B) relative to the total volume of the thermoplastic resin (A) and the dielectric filler (B) is preferably 50% by volume or less, more preferably 40% by volume or less, even more preferably 35% by volume or less, and even more preferably 25% by volume or less.

[0051] In the above, the volume content of the dielectric material in the adhesive layer has been described as the volume content when the dielectric material is a dielectric filler (B). The volume content of the dielectric material in the adhesive layer is not limited to when the dielectric material is a dielectric filler (B), and even when the dielectric material is a dielectric material other than the dielectric filler (B), it is preferable that the volume content 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% by volume or more and 50% by volume or less.

[0052] (Average particle size) 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. 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. When the volume average particle diameter of the dielectric filler (B) is 1 μm or more, the high-frequency dielectric heating adhesive sheet exhibits high heat-generating performance when a high-frequency electric field is applied, and the adhesive layer can be firmly bonded to a glass substrate in a short time. By making the volume average particle diameter of the dielectric filler (B) 30 μm or less, the high-frequency dielectric heating adhesive sheet exhibits high heat-generating performance when a high-frequency electric field is applied, and the adhesive layer can be firmly bonded to the glass substrate in a short time. In addition, by making the volume average particle diameter of the dielectric filler (B) 30 μm or less, a decrease in the strength of the high-frequency dielectric heating adhesive sheet can be prevented.

[0053] The volume average particle diameter of the dielectric filler (B) is measured by the following method: The particle size distribution of the dielectric filler (B) is measured by a laser diffraction / scattering method, and the volume average particle diameter is calculated from the results of the particle size distribution measurement in accordance with JIS Z 8819-2:2001.

[0054] In the high-frequency dielectric heating adhesive sheet according to this embodiment, the average particle diameter D of the dielectric filler (B) F and the thickness T of the adhesive layer, and 1≦T / D F It is preferable that the relationship ≦2500 is satisfied. T / D F is preferably 1 or more, more preferably 2 or more, more preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. F If the value is 1 or more, it is possible to prevent a decrease in adhesive strength caused by contact between the dielectric filler (B) and the adherend during adhesion. T / D F is preferably 2500 or less, preferably 2000 or less, preferably 1750 or less, more preferably 1000 or less, even more preferably 500 or less, even more preferably 100 or less, and even more preferably 50 or less. F If the value is 2500 or less, the load on the sheet manufacturing apparatus can be reduced when the high frequency dielectric heating adhesive sheet is produced.

[0055] (additives) The high-frequency dielectric heating adhesive sheet according to this embodiment may or may not contain an additive. When the high-frequency dielectric heating adhesive sheet according to this embodiment is composed of multiple layers, at least one of the multiple layers may or may not contain an additive. When at least one of the multiple layers contains an additive, the adhesive layer may or may not contain an additive.

[0056] When the high-frequency dielectric heating adhesive sheet according to this embodiment contains an additive, examples of the additive include a tackifier, a plasticizer, a wax, a colorant, an antioxidant, an ultraviolet absorber, an antibacterial agent, a coupling agent, a viscosity modifier, an organic filler, an inorganic filler, etc. The organic filler and the inorganic filler as additives are different from the dielectric material (dielectric filler).

[0057] The tackifier and plasticizer can improve the melting and adhesive properties of the high frequency dielectric heating adhesive sheet. Examples of tackifiers 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. Examples of plasticizers include petroleum-based process oils, natural oils, dialkyl dibasic acids, and low-molecular-weight liquid polymers. Examples of petroleum-based process oils include paraffin-based process oils, naphthenic process oils, and aromatic process oils. Examples of natural oils include castor oil and tall oil. Examples of dialkyl dibasic acids include dibutyl phthalate, dioctyl phthalate, and dibutyl adipate. Examples of low-molecular-weight liquid polymers include liquid polybutene and liquid polyisoprene.

[0058] When the high-frequency dielectric heating adhesive sheet according to this embodiment contains an additive, the content of the additive in the high-frequency dielectric heating adhesive sheet is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on the total amount of the high-frequency dielectric heating adhesive sheet. The content of the additive in the high-frequency dielectric heating adhesive sheet is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0059] The high-frequency dielectric heating adhesive sheet according to this embodiment preferably does not contain a solvent. A solvent-free high-frequency dielectric heating adhesive sheet is less likely to cause problems with VOCs (Volatile Organic Compounds) that are caused by the adhesive used to bond the sheet to the adherend.

[0060] The adhesive layer of the high-frequency dielectric heating adhesive sheet according to this embodiment preferably does not contain conductive materials such as carbon or carbon compounds containing carbon as the main component (e.g., carbon black, etc.) and metals, etc. For example, the adhesive layer preferably does not contain carbon steel, α-iron, γ-iron, δ-iron, copper, brass, aluminum, iron-nickel alloy, iron-nickel-chromium alloy, carbon fiber, or carbon black.

[0061] When the adhesive layer contains a conductive substance, the content of the conductive substance in the adhesive layer is, independently, preferably 20 mass% or less, more preferably 10 mass% or less, even more preferably 5 mass% or less, even more preferably 1 mass% or less, and even more preferably 0.1 mass% or less, based on the total amount of the adhesive layer. It is particularly preferable that the content of the conductive material in the adhesive layer is 0% by mass. If the content of the conductive substance in the adhesive layer is 20 mass % or less, it becomes easier to prevent the problem of carbonization of the adhesive joint and the adherend due to electrical breakdown during dielectric heating treatment.

[0062] In the adhesive layer of the high-frequency dielectric heating adhesive sheet according to this embodiment, the total content of the thermoplastic resin (A) and the dielectric filler (B) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 99% by mass or more.

[0063] In one embodiment, the high-frequency dielectric heating adhesive sheet according to the present invention is composed of only one adhesive layer having high-frequency dielectric adhesive properties. However, the high-frequency dielectric heating adhesive sheet according to the present invention is not limited to an embodiment consisting of only one adhesive layer, and other embodiments of the high-frequency dielectric heating adhesive sheet include an embodiment in which layers other than the adhesive layer are laminated. In this way, a high-frequency dielectric heating adhesive sheet may consist of only one adhesive layer with high-frequency dielectric adhesive properties, and therefore, in this specification, the terms "high-frequency dielectric heating adhesive sheet" and "adhesive layer" may be interchangeable in some cases. 1A to 1C show schematic diagrams of a number of aspects of the high-frequency dielectric heating adhesive sheet according to this embodiment.

[0064] 1A 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 opposite to the first surface 11. The high-frequency dielectric heating adhesive sheet preferably consists of only a single adhesive layer, which allows the high-frequency dielectric heating adhesive sheet to be thin and easy to mold.

[0065] The high-frequency dielectric heating adhesive sheet 1B shown in FIG. 1B has an adhesive layer 10 and a substrate 30 that supports the adhesive layer 10. Like 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 material that can support the adhesive layer 10. Examples include a resin film or resin sheet containing at least one resin selected from the group consisting of polyolefin resins such as polyethylene resin and polypropylene resin, polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin, acetate resin, ABS resin, polystyrene resin, and vinyl chloride resin. The substrate 30 may 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.

[0066] The high-frequency dielectric heating adhesive sheet 1C shown in Fig. 1C 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 may be referred to as a first adhesive layer, and the adhesive layer 20 may be referred to as a second adhesive layer. In a high-frequency dielectric heating adhesive sheet having an intermediate layer disposed between the first adhesive layer and the second adhesive layer, it is sufficient that the first adhesive layer satisfies the conditions of the adhesive layers of the high-frequency dielectric heating adhesive sheet of this embodiment. In one aspect, both the first adhesive layer and the second adhesive layer are layers with the same composition and properties. In another aspect, the second adhesive layer is a high-frequency dielectric heating adhesive layer that differs from the first adhesive layer in at least one of its composition and properties. In another aspect, the second adhesive layer is a general adhesive layer that is not a high-frequency dielectric heating adhesive layer. Examples of the second adhesive layer that is not high-frequency dielectric heating adhesive include a layer of a drying and solidifying type adhesive that dries and solidifies as water or a solvent evaporates, or an adhesive layer formed from an adhesive (pressure-sensitive adhesive).

[0067] <Form and characteristics of high frequency dielectric heating adhesive sheet> In one embodiment, the high-frequency dielectric heating adhesive sheet according to this embodiment may consist of only one adhesive layer, while in another embodiment, it may consist of multiple layers. When the high-frequency dielectric heating adhesive sheet consists of only one adhesive layer, the adhesive layer itself corresponds to the high-frequency dielectric heating adhesive sheet, and the shape and characteristics of the high-frequency dielectric heating adhesive sheet correspond to the shape and characteristics of the adhesive layer.

[0068] (Softening temperature) The softening temperature of the high frequency dielectric heating adhesive sheet according to this embodiment is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. The softening temperature of the high frequency dielectric heating adhesive sheet according to this embodiment is preferably 160°C or lower, more preferably 130°C or lower, and even more preferably 100°C or lower. When a high-frequency dielectric heating adhesive sheet has a softening temperature of 50°C or higher, deformation of the high-frequency dielectric heating adhesive sheet is easily suppressed when an external force is applied to an assembly in which a glass adherend is bonded using the high-frequency dielectric heating adhesive sheet. For example, the property of easily suppressing deformation of the high-frequency dielectric heating adhesive sheet makes it suitable for use in environments where the assembly is likely to become hot. High-frequency dielectric heating adhesive sheets with a softening temperature of 50°C or higher are suitable for use in mobile objects such as buildings and automobiles that are exposed to the outdoors. If the softening temperature of the high-frequency dielectric heating adhesive sheet is 160°C or less, it becomes easier to obtain adhesive strength in a short period of time. The softening temperature of a high-frequency dielectric heating adhesive sheet can be measured by the following method. Using a drop-type flow tester (Shimadzu Corporation, model number "CFT-100D"), the temperature of the measurement sample is raised at a heating rate of 10°C / min under the following drop-type flow tester test conditions, while the stroke displacement rate (mm / min) that varies with the temperature rise is measured to obtain a temperature dependence chart of the sample's stroke displacement rate. The softening temperature is determined by the temperature dependence chart, which shows the peak temperature at the low temperature side. The high-frequency dielectric heating adhesive sheet is cut into 3 mm square flake-shaped measurement samples, and the softening temperature is measured using these samples. <Drop-type flow tester test conditions> Test temperature: 190℃ Load capacity: 5kg Die: Hole diameter φ2.0mm, length 5.0mm Cylinder diameter: 11.329mm

[0069] (storage modulus) The storage modulus at 20° C. of the high-frequency dielectric heating adhesive sheet according to this embodiment is preferably 5 MPa or more, more preferably 10 MPa or more, and even more preferably 20 MPa or more. The storage modulus at 20°C of the high-frequency dielectric heating adhesive sheet according to this embodiment is preferably 600 MPa or less, more preferably 400 MPa or less, even more preferably 300 MPa or less, and even more preferably 200 MPa or less. When the storage modulus of the high-frequency dielectric heating adhesive sheet at 20°C is 5 MPa or more, the sheet does not become too soft and has self-supporting properties, making it easy to prevent a decrease in work efficiency when using the sheet. When the storage modulus of the high-frequency dielectric heating adhesive sheet at 20°C is 600 MPa or less, the sheet becomes difficult to process. The storage modulus of the high-frequency dielectric heating adhesive sheet at 20° C. can be measured by the method described in the Examples section below.

[0070] (loss tangent peak temperature) The loss tangent peak temperature of the high-frequency dielectric heating adhesive sheet according to this embodiment is preferably 30°C or less, more preferably 20°C or less, even more preferably 10°C or less, and even more preferably 0°C or less. The loss tangent peak temperature of the high frequency dielectric heating adhesive sheet is usually -60°C or higher. When the loss tangent peak temperature of the high-frequency dielectric heating adhesive sheet is 30°C or less, it is easy to obtain impact resistance in the low temperature range. In addition, when the loss tangent peak temperature is 30°C or less, peeling at the interface between the adherend and the adhesive layer due to vibration or impact is suppressed, making it easy to ensure bonding strength. The loss tangent peak temperature of the high frequency dielectric heating adhesive sheet can be measured by the method described in the Examples section below.

[0071] (Thickness of high frequency dielectric heating adhesive sheet) The thickness of the high frequency dielectric heating adhesive sheet according to this embodiment is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 50 μm or more. If the thickness of the high-frequency dielectric heating adhesive sheet is 5 μm or more, the high-frequency dielectric heating adhesive sheet can easily conform to the irregularities of the adherend when adhering to the adherend, and adhesive strength can be easily achieved. When the high-frequency dielectric heating adhesive sheet has a multilayer structure consisting of multiple layers, the thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 50 μm or more. When the high-frequency dielectric heating adhesive sheet is a multi-layered sheet, if the thickness of the adhesive layer is 5 μm or more, the adhesive layer will easily conform to the unevenness of the adherend when adhering to the adherend, making it easier to develop adhesive strength. There is no particular upper limit to the thickness of the high-frequency dielectric heating adhesive sheet. As the thickness of the high-frequency dielectric heating adhesive sheet increases, the weight of the entire bonded body obtained by bonding the high-frequency dielectric heating adhesive sheet to the adherend also increases. Therefore, it is preferable that the high-frequency dielectric heating adhesive sheet has a thickness within a range that does not cause problems in practical use. Taking into consideration 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 even more preferably 600 μm or less.

[0072] (Method of manufacturing high frequency dielectric heating adhesive sheet) The single-layer high-frequency dielectric heating adhesive sheet can be produced by premixing the above-mentioned components, kneading them using a known kneading device such as an extruder or a heat roll, and then by a known molding method such as extrusion molding, calendar molding, injection molding, or casting molding. When the high-frequency dielectric heating adhesive sheet according to this embodiment has a multilayer structure, it can be produced, for example, by premixing the above-mentioned components and coextrusion using a multilayer extruder. Alternatively, a multilayer sheet can be produced by individually preparing single-layer sheets for each layer (e.g., the first adhesive layer, intermediate layer, and second adhesive layer) that make up the high-frequency dielectric heating adhesive sheet according to this embodiment, and then laminating multiple single-layer sheets together. When laminating multiple single-layer sheets, for example, a thermal laminator can be used. In addition, the high-frequency dielectric heating adhesive sheet according to this embodiment can also be produced by thermal extrusion coating, in which a molten adhesive layer is coated onto a substrate, or by hot melt coating, or by wet coating, in which a coating liquid in which the adhesive layer composition is dispersed or dissolved in a solvent is coated onto a substrate.

[0073] (How to use high frequency dielectric heating adhesive sheet) The high-frequency dielectric heating adhesive sheet according to this embodiment can be used to bond to an adherend, and can also be used to bond multiple adherends together. The material of the adherend is not particularly limited, and may be either an organic material or an inorganic material (including metal materials), or may be a composite material of an organic material and an inorganic material. Examples of organic materials that can be used as the adherend include plastic materials and rubber materials. Examples of plastic materials include polypropylene resin, polyethylene resin, polyurethane resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polycarbonate resin (PC resin), polyamide resin (such as nylon 6 and nylon 66), polyester resin (such as polyethylene terephthalate (PET resin) and polybutylene terephthalate resin (PBT resin)), polyacetal resin (POM resin), polymethyl methacrylate resin, and polystyrene resin. Examples of rubber materials include styrene-butadiene rubber (SBR), ethylene propylene rubber (EPR), and silicone rubber. The adherend may also be a foamed organic material. Examples of inorganic materials that can be used as the adherend include glass, cement, ceramic, and metal materials. The adherend may also be a fiber-reinforced plastic (FRP), a composite material made of fibers and the aforementioned plastic materials. The plastic material in the fiber-reinforced resin is 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 (such as nylon 6 and nylon 66), polyester resin (such as polyethylene terephthalate (PET resin) and polybutylene terephthalate resin (PBT resin)), polyacetal resin (POM resin), polymethyl methacrylate resin, and polystyrene resin. Examples of fibers in the fiber-reinforced resin include glass fiber, Kevlar fiber, and carbon fiber. When a plurality of adherends are bonded together using the high-frequency dielectric heating adhesive sheet according to this embodiment, the adherends may be made of the same material or different materials. The high-frequency dielectric heating adhesive sheet according to this embodiment can be suitably used for bonding to glass adherends. When bonding multiple adherends together, as long as at least one of the adherends is made of glass, the high-frequency dielectric heating adhesive sheet according to this embodiment can be firmly bonded to the glass adherend. The shape of the adherend is not particularly limited, but it is preferable that it has a surface to which the high-frequency dielectric heating adhesive sheet can be attached, and that it is preferably in the form of a sheet or plate. When multiple adherends are to be bonded together, the shapes and dimensions of the adherends may be the same or different from each other.

[0074] [Adhesion method] The bonding method according to this embodiment is a bonding method that uses the high-frequency dielectric heating adhesive sheet according to this embodiment. As an example of the bonding method according to this embodiment, a high-frequency dielectric heating adhesive sheet consisting of a single adhesive layer is used to bond a first adherend and a second adherend, but the present invention is not limited to this embodiment. The material of the second adherend is also not particularly limited.

[0075] The bonding method according to one aspect of this embodiment includes the following steps P1 and P2.

[0076] ·Process P1 Step P1 is a step of sandwiching the high-frequency dielectric heating adhesive sheet according to 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. Also, in step P1, the second adherend is brought into contact with the second surface of the high-frequency dielectric heating adhesive sheet.

[0077] The high-frequency dielectric heating adhesive sheet may be sandwiched between the first and second adherends so as to bond them together. The high-frequency dielectric heating adhesive sheet may be sandwiched between the first and second adherends in a portion, multiple locations, or the entire surface. To improve the adhesive strength between the first and second adherends, it is preferable to sandwich the high-frequency dielectric heating adhesive sheet over the entire adhesive surface between the first and second adherends. Another example of sandwiching the high-frequency dielectric heating adhesive sheet over a portion between the first and second adherends is to arrange the high-frequency dielectric heating adhesive sheet in a frame shape along the periphery of the adhesive surface between the first and second adherends and sandwich it between the first and second adherends. Arranging the high-frequency dielectric heating adhesive sheet in this frame shape improves adhesive strength between the first and second adherends and reduces the weight of the bonded body compared to when the high-frequency dielectric heating adhesive sheet is arranged over the entire adhesive surface. In addition, according to one embodiment in which a high-frequency dielectric heating adhesive sheet is sandwiched between a portion of the first adherend and a second adherend, the size of the high-frequency dielectric heating adhesive sheet used can be reduced, thereby shortening the high-frequency dielectric heating treatment time compared to when the high-frequency dielectric heating adhesive sheet is placed over the entire adhesive surface.

[0078] ·Process P2 Step P2 is a step of applying a high-frequency electric field of 3 MHz or more and 300 MHz or less to the high-frequency dielectric heating adhesive sheet sandwiched between the first adherend and the second adherend in step P1, thereby bonding the first adherend and the second adherend with the high-frequency dielectric heating adhesive sheet. For example, a high-frequency electric field can be applied to a high-frequency dielectric heating adhesive sheet by using a dielectric heating bonding device. In this specification, the "dielectric heating device" may also be referred to as a "dielectric heating bonding device" or a "high-frequency dielectric heating device."

[0079] FIG. 2 shows a schematic diagram illustrating a high-frequency dielectric heating treatment using the high-frequency dielectric heating adhesive sheet and dielectric heating device according to this embodiment.

[0080] (Dielectric heating bonding device) FIG. 2 shows a schematic diagram of a dielectric heating bonding apparatus 50. 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 supply 53 . 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 pressing mechanism. This pressing mechanism allows the first adherend 110, the high-frequency dielectric heating adhesive sheet 1A, and the second adherend 120 to be pressurized between the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52.

[0081] When the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 form a pair of parallel plate electrodes, this electrode arrangement is sometimes called a parallel plate type. It is also preferable to use a parallel-plate type high-frequency dielectric heating device to apply the high-frequency electric field.With a parallel-plate type high-frequency dielectric heating device, the high-frequency waves penetrate the high-frequency dielectric heating adhesive sheet located between the electrodes, so the entire high-frequency dielectric heating adhesive sheet can be heated and the adherend and the high-frequency dielectric heating adhesive sheet can be bonded in a short time.

[0082] A high frequency power supply 53 is connected to each of the first high frequency electric field applying electrode 51 and the second high frequency electric field applying electrode 52 to apply a high frequency electric field of, for example, about 13.56 MHz, about 27.12 MHz, or about 40.68 MHz. 2, the dielectric heating bonding apparatus 50 performs a dielectric heating treatment via a high-frequency dielectric heating adhesive sheet 1A sandwiched between a first adherend 110 and a second adherend 120. In addition to the dielectric heating treatment, the dielectric heating bonding apparatus 50 also bonds the first adherend 110 and the second adherend 120 by a pressure treatment using a first high-frequency electric field application electrode 51 and a second high-frequency electric field application electrode 52. Note that the first adherend 110 and the second adherend 120 may also be bonded without the pressure treatment.

[0083] When a high-frequency electric field is applied between the first high-frequency electric field application electrode 51 and the second high-frequency electric field application electrode 52, the dielectric filler (not shown) dispersed in the adhesive component of the high-frequency dielectric heating adhesive sheet 1A absorbs the high-frequency energy. The dielectric filler functions as a heat source, and the heat generated by the dielectric filler melts the thermoplastic resin component, ultimately resulting in a strong bond between the first adherend 110 and the second adherend 120, even with a short processing time.

[0084] The first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 have a pressing mechanism and therefore function as a pressing device. Therefore, the first adherend 110 and the second adherend 120 can be more firmly bonded together by the compression direction pressure applied by the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 and the heat melting of the high-frequency dielectric heating adhesive sheet 1A.

[0085] (High frequency dielectric heating bonding conditions) The high-frequency dielectric heating bonding conditions can be changed as appropriate, but the following conditions are preferred.

[0086] The output of the high frequency electric field is preferably 10 W or more, more preferably 30 W or more, even more preferably 50 W or more, and even more preferably 80 W or more. The output of the high frequency electric field is preferably 50,000 W or less, more preferably 20,000 W or less, even more preferably 15,000 W or less, even more preferably 10,000 W or less, and even more preferably 1,000 W or less. If the output of the high frequency electric field is 10 W or more, the problem of the temperature not rising easily during the dielectric heating process can be prevented, and good adhesive strength can be easily obtained. If the output of the high frequency electric field is 50,000 W or less, it is easy to prevent the problem of temperature control becoming difficult during dielectric heating treatment.

[0087] The application time of the high frequency electric field is preferably 1 second or more. The application time of the high frequency electric field is preferably 300 seconds or less, more preferably 240 seconds or less, even more preferably 180 seconds or less, even more preferably 120 seconds or less, and even more preferably 100 seconds or less. If the application time of the high frequency electric field is 1 second or more, the problem of the temperature not rising easily during the dielectric heating process can be prevented, and good adhesive strength can be easily obtained. If the application time of the high-frequency electric field is 300 seconds or less, it is easy to prevent problems such as a decrease in the production efficiency of the bonded body in which a first adherend and a second adherend are bonded, an increase in production costs, and thermal deterioration of the adherends.

[0088] The frequency of the applied high frequency electric field is preferably 1 kHz or higher, more preferably 1 MHz or higher, even more preferably 5 MHz or higher, and even more preferably 10 MHz or higher. The frequency of the applied high-frequency electric field is preferably 300 MHz or less, more preferably 100 MHz or less, even more preferably 80 MHz or less, and even more preferably 50 MHz or less. Specifically, the industrial frequency bands of 13.56 MHz, 27.12 MHz, and 40.68 MHz assigned by the International Telecommunication Union are also used in the high-frequency dielectric heating bonding method (bonding method) of this embodiment.

[0089] (Effects of this embodiment) The high-frequency dielectric heating adhesive sheet according to this embodiment can be bonded to glass with high adhesive strength even with low energy consumption.

[0090] The high-frequency dielectric heating adhesive sheet according to this embodiment is easier to handle than adhesives that require application, and workability during bonding to an adherend is improved.

[0091] The high frequency dielectric heating adhesive sheet according to this embodiment has superior water resistance and moisture resistance compared to general adhesives.

[0092] The high-frequency dielectric heating adhesive sheet according to this embodiment is heated by the application of a high-frequency electric field, which causes localized heating of the high-frequency dielectric heating adhesive sheet, making it easier to prevent the entire adherend from melting when it is bonded to the adherend.

[0093] According to the bonding method using the high-frequency dielectric heating adhesive sheet of this embodiment, it is possible to locally heat only specified locations from the outside using a dielectric heating bonding device. Therefore, the bonding method using the high-frequency dielectric heating adhesive sheet of this embodiment is effective even when the adherend is a large and complex three-dimensional structure or a thick and complex three-dimensional structure, etc., and even when high dimensional accuracy is required.

[0094] Furthermore, with the high-frequency dielectric heating adhesive sheet according to this embodiment, the thickness of the high-frequency dielectric heating adhesive sheet can be appropriately controlled. Therefore, the high-frequency dielectric heating adhesive sheet according to this embodiment can be applied to the roll-to-roll method, and the high-frequency dielectric heating adhesive sheet can be processed into any area and shape by punching or the like to match the adhesive area with the adherend and the shape of the adherend. Therefore, the high-frequency dielectric heating adhesive sheet according to this embodiment has great advantages from the viewpoint of the manufacturing process.

[0095] [Modifications of the embodiment] The present invention is not limited to the above-described embodiment, and may include modifications and improvements within the scope of achieving the object of the present invention.

[0096] As a high-frequency dielectric heating adhesive sheet according to another embodiment different from the above embodiment, for example, the following high-frequency dielectric heating adhesive sheet can be mentioned. [1] In one embodiment, the high-frequency dielectric heating adhesive sheet has an adhesive layer containing at least a thermoplastic resin (A) and a dielectric material (preferably a dielectric filler (B)) that generates heat upon application of a high-frequency electric field, the thermoplastic resin (A) containing at least a first thermoplastic resin (A1) and a second thermoplastic resin (A2), the first thermoplastic resin (A1) being a silane-modified polyolefin, and the second thermoplastic resin (A2) being another thermoplastic resin different from the silane-modified polyolefin. [2] In the high-frequency dielectric heating adhesive sheet according to [1], the second thermoplastic resin (A2) is preferably a resin having an acid-modified structure. [3] In the high-frequency dielectric heating adhesive sheet according to [1] or [2], the second thermoplastic resin (A2) is preferably a polyolefin resin having an acid-modified structure. In the high-frequency dielectric heating adhesive sheets according to the above items [1] to [3], the silane-modified polyolefin and the other thermoplastic resin different from the silane-modified polyolefin are, for example, the resins described in the above embodiments. When the adhesive layer is a mixture of a silane-modified polyolefin and another thermoplastic resin as the thermoplastic resin, the viscosity of the adhesive layer can be easily adjusted, the high-frequency dielectric heating adhesive sheet can be easily made processable, and unintended crosslinking reactions can be suppressed, which makes it easy to prevent deterioration of adhesive strength over time.

[0097] The high-frequency dielectric heating adhesive sheet may have an adhesive portion. By having an adhesive portion, it is possible to prevent misalignment when sandwiching the high-frequency dielectric heating adhesive sheet between two adherends and to position it accurately. The adhesive portion may be provided on one side of the high-frequency dielectric heating adhesive sheet or on both sides. The adhesive portion may also be provided partially on one side of the high-frequency dielectric heating adhesive sheet. Even if the high-frequency dielectric heating adhesive sheet does not have an adhesive portion, it can firmly bond a first adherend and a second adherend.

[0098] The high-frequency dielectric heating process is not limited to the dielectric heating bonding device with electrodes arranged opposite to each other as described in the above embodiment, and a grid-type high-frequency dielectric heating device may also be used. A grid-type high-frequency dielectric heating device has a grid electrode in which electrodes of a first polarity and electrodes of a second polarity opposite to the first polarity are alternately arranged at regular intervals on the same plane. For example, when producing a bonded body in which the end of a first adherend and the end of a second adherend are overlapped and bonded, a grid electrode type high-frequency dielectric heating device is placed on the first adherend side or the second adherend side to apply a high-frequency electric field.

[0099] When a first adherend and a second adherend are bonded using a grid electrode type high-frequency dielectric heating device, a first grid electrode may be placed on the first adherend side and a second grid electrode may be placed on the second adherend side, and the first adherend, high-frequency dielectric heating adhesive sheet, and second adherend may be sandwiched between the first grid electrode and the second grid electrode and a high-frequency electric field may be applied simultaneously.

[0100] When a first adherend and a second adherend are bonded using a grid electrode type high-frequency dielectric heating device, a grid electrode may be placed on one side of each of the first adherend and the second adherend, a high-frequency electric field may be applied, and then a grid electrode may be placed on the other side of each of the first adherend and the second adherend, and a high-frequency electric field may be applied.

[0101] It is also preferable to use a grid electrode type high-frequency dielectric heating device to apply the high-frequency electric field. By using a grid electrode type high-frequency dielectric heating device, the adherends can be bonded together by dielectrically heating the surface side of the first and second adherends, for example, the side closest to the high-frequency dielectric heating adhesive sheet, without being affected by the thickness of the first and second adherends. Furthermore, using a grid electrode type high-frequency dielectric heating device can achieve energy savings in the production of bonded bodies.

[0102] For the sake of simplicity, the drawings show an example in which a dielectric heating bonding device is used in which electrodes are arranged opposite each other. [Example]

[0103] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0104] [Preparation of high-frequency dielectric heating adhesive sheet] (Examples 1 to 5 and Comparative Examples 1 to 4) The materials shown in Table 1 were premixed. The premixed materials were fed into the hopper of a 30 mm diameter twin-screw extruder, and the cylinder temperature was set to 180°C or higher and 200°C or lower, and the die temperature was set to 200°C, where the premixed materials were melt-kneaded. The melt-kneaded materials were cooled and then cut to produce granular pellets. The produced granular pellets were then fed into the hopper of a single-screw extruder equipped with a T-die. The cylinder temperature was set to 200°C, the die temperature was set to 200°C, and a film-like melt-kneaded material was extruded from the T-die. The film-like melt-kneaded material was then cooled on a cooling roll to produce each of the 400 μm-thick high-frequency dielectric heating adhesive sheets according to Examples 1 to 5 and Comparative Examples 1 to 4.

[0105] The thermoplastic resins and fillers shown in Table 1 are described as follows. Silane-modified PE1: Silane-modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "Linkron SS732N" Silane-modified PE2: Silane-modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "Linkron SF800N" Silane-modified PP1: Silane-modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "Linkron PM700N" Silane-modified PP2: Silane-modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "Linkron PK500N" m-PP: Maleic anhydride modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "Modic P565" m-PE: Maleic anhydride modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "Modic M545" EVA: Ethylene vinyl acetate copolymer, manufactured by Mitsui DuPont Polychemicals Co., Ltd., product name "Evaflex EV560" Zinc oxide (ZnO): Zinc oxide with a volume average particle size of 11 μm. Manufactured by Sakai Chemical Industry Co., Ltd., product name "LP-ZINC11" Iron powder: Iron powder with a volume average particle size of 10 μm

[0106] (MFR: Melt flow rate) The MFR of the thermoplastic resin at 190°C was measured in accordance with JIS K 7210-1:2014 using a descending flow tester (manufactured by Shimadzu Corporation, model number "CFT-100D"). When a mixture of multiple thermoplastic resins was used, the multiple resins were kneaded in a twin-screw kneader in the ratios 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.

[0107] (Volume average particle size of dielectric filler) The particle size distribution of the dielectric filler was measured by laser diffraction / scattering. The volume average particle diameter was calculated from the particle size distribution measurement results in accordance with JIS Z 8819-2:2001. The calculated volume average particle diameter of zinc oxide (ZnO) was 11 μm, and the volume average particle diameter of iron powder was 10 μm.

[0108] [Evaluation of high frequency dielectric heating adhesive sheet] The high frequency dielectric heating adhesive sheet was evaluated as follows, and the evaluation results are shown in Table 1.

[0109] (Evaluation of wetting and spreading properties) As one index for evaluating high-frequency adhesiveness, the wettability and spreadability of the adhesive sheet was evaluated. The high-frequency dielectric heating adhesive sheet thus prepared was cut into a size of 13 mm x 6.5 mm. The cut high-frequency dielectric heating adhesive sheet was placed between a pair of soda-lime glass sheets (25 mm x 100 mm x 3 mm (thickness)) as adherends. The area of ​​the overlapping part of the soda-lime glass was 25 mm x 12.5 mm = 312.5 mm. 2 Specifically, a glass adherend WK1, a glass adherend WK2, and an adhesive sheet AS1 (corresponding to the high-frequency dielectric heating adhesive sheet produced) were arranged with the dimensions shown in FIG. 3A and as shown in FIG. 3B. After arranging them in this manner, the 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 ​​the pair of electrodes of the high-frequency dielectric heating device was 800 mm2 each. 2 The electrodes were placed so as to cover the overlapping portion of the adherend (soda lime glass) (40mm x 20mm). In this 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. High frequency application conditions Frequency: 40.68MHz Output: 200W Application time: 90 seconds Pressing pressure: 0.5 MPa The pressure during application of high frequency is the pressure applied to the joint between the first adherend and the second adherend.

[0110] After applying a high-frequency electric field, when viewed in plan, the area of ​​the overlapping portion of adherends WK1 and WK2 was taken as 100%, and the percentage of the area of ​​the overlapping portion that was wetted and spread by adhesive sheet AS1 was measured using image analysis software, and the wettability and spreadability of the adhesive sheet were evaluated according to the following criteria: Before application, the area ratio of the adhesive sheet to the area of ​​the overlapping portion of the adherends was 27%. A: The adhesive sheet accounts for 80% or more of the area of ​​the overlapping parts of the adherends. B: The area ratio of the adhesive sheet to the area of ​​the overlapping parts of the adherends is 55% or more but less than 80%. F: The area ratio of the adhesive sheet to the area of ​​the overlapping parts of the adherends is less than 55%. FIG. 3C is a plan view showing a state in which the overlapping portions of the adherends are completely filled in after the application of a high-frequency electric field and the resin protrudes from the adherends. In this case, the result is evaluation A.

[0111] (Adhesive strength (tensile shear strength)) Test pieces for adhesive strength evaluation were prepared in the same manner as described above (evaluation of wetting and spreading properties), except that the high-frequency dielectric heating adhesive sheet was cut to a size of 25 mm x 12.5 mm and positioned so that the adhesive sheet coincided with the overlapping portion of the adherend. Using these test pieces for adhesive strength evaluation, the tensile shear strength (unit: MPa) was measured as the adhesive strength. A universal tensile tester (Instron Corporation, product name "Instron 5581") was used to measure the tensile shear strength. The tensile speed for measuring the tensile shear strength was 10 mm / min. Note that "not bonded" in the tensile shear strength column in the table means that the adhesive sheet easily peeled off from the adherend before use in measuring the tensile shear strength. Also, "4<" in the table means that the tensile shear strength was greater than 4 MPa. Furthermore, the fracture mode of the test piece for evaluating high frequency adhesiveness in the measurement of tensile shear strength was observed, and the adhesiveness was evaluated according to the following criteria: Tensile shear strength was measured in accordance with JIS K 6850:1999. A: Cohesive failure of high frequency dielectric heating adhesive sheet B: Destruction of the adherend F: Interfacial peeling between the high-frequency dielectric heating adhesive sheet and the adherend

[0112] (Softening temperature) Using a drop-type flow tester (Shimadzu Corporation, model number "CFT-100D"), the temperature of the test sample was increased at a rate of 10°C / min under the following drop-type flow tester test conditions, while the stroke displacement rate (mm / min) that varied with the temperature increase was measured to obtain a temperature dependence chart of the sample's stroke displacement rate. The peak temperature on the low-temperature side of this chart was taken as the softening temperature. The softening temperature was measured using 3mm square flake-shaped test samples obtained by cutting the high-frequency dielectric heating adhesive sheet. <Drop-type flow tester test conditions> Test temperature: 190℃ Load capacity: 5kg Die: Hole diameter φ2.0mm, length 5.0mm Cylinder diameter: 11.329mm

[0113] (Storage modulus and loss tangent peak temperature) The storage modulus E' of the high-frequency dielectric heating adhesive sheet at 20°C was obtained by measuring its viscoelasticity using a dynamic viscoelasticity measuring device (Rheovibron DDV-01FP, manufactured by Orientec Co., Ltd.) Specifically, a 4mm wide high-frequency dielectric heating adhesive sheet was attached to the dynamic viscoelasticity measuring device with a measurement distance (distance between chucks) of 10mm, and the viscoelasticity of the high-frequency dielectric heating adhesive sheet was measured in tensile mode at a frequency of 11Hz, a strain of 0.0015, a temperature rise of 4°C / min, and a temperature range of -100°C to 130°C. The loss tangent peak temperature of the high frequency dielectric heating adhesive sheet was the temperature at the maximum point of tan δ (loss modulus / storage modulus) obtained in the above-mentioned viscoelasticity measurement.

[0114] [Table 1]

[0115] The high frequency dielectric heating adhesive sheets of Examples 1 to 5 were able to bond glass adherends together with high adhesive strength even with low energy consumption. [Explanation of symbols]

[0116] 10...adhesive layer (first adhesive layer), 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, 20...adhesive layer (second adhesive layer), 21...second surface, 30...substrate, 40...intermediate layer, 50...dielectric heating bonding device, 51...first high frequency electric field application electrode, 52...second high frequency electric field application electrode, 53...high frequency power supply, AS1...adhesive sheet, WK1...adherend, WK2...adherend.

Claims

1. A high-frequency dielectric heating adhesive sheet having an adhesive layer containing at least a thermoplastic resin (A) and a dielectric material that generates heat upon application of a high-frequency electric field, The adhesive layer contains a silane-modified polyolefin as the thermoplastic resin (A), the content of the silane-modified polyolefin in the thermoplastic resin (A) is 40% by volume or more and 100% by volume or less; the thermoplastic resin (A) has an MFR at 190°C of 2 g / 10 min or more and 50 g / 10 min or less; The frequency range of the high frequency electric field is 3 MHz or more and 300 MHz or less, The dielectric material is a dielectric filler (B), The volume content of the dielectric filler (B) in the adhesive layer is 10% by volume or more and 40% by volume or less, The dielectric filler (B) is zinc oxide, The loss tangent peak temperature of the adhesive layer is 30°C or less, The loss tangent peak temperature is the temperature at the maximum point of tan δ (loss modulus / storage modulus) obtained by measuring the viscoelasticity of the adhesive layer in a tensile mode at a frequency of 11 Hz, a strain of 0.0015, a temperature rise of 4°C / min, and a temperature range of -100°C to 130°C. High frequency dielectric heating adhesive sheet.

2. The softening temperature of the adhesive layer is 50°C or higher and 160°C or lower. The high-frequency dielectric heating adhesive sheet according to claim 1 .

3. The adhesive layer has a storage modulus of 5 MPa or more at 20°C, The storage modulus is obtained by measuring the viscoelasticity of the adhesive layer in a tensile mode at a frequency of 11 Hz, a strain of 0.0015, a temperature rise of 4°C / min, and a temperature range of -100°C to 130°C. The high-frequency dielectric heating adhesive sheet according to claim 1 or 2.

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

5. The thickness of the high-frequency dielectric heating adhesive sheet is 5 μm or more. The high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 4.

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