High-frequency dielectric heating adhesive sheet

Abstract

Provided is 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 by application of a high-frequency electric field, wherein the adhesive layer (10) contains, as the thermoplastic resin (A), a silane-modified polyolefin, and the thermoplastic resin (A) has an MFR at 190°C of 2 g / 10 min or more and 50 g / 10 min or less.

Description

Technical Field

[0001] This invention relates to high-frequency dielectric heating adhesive sheets. Background Technology

[0002] In recent years, as a method for bonding objects that are usually difficult to bond together, methods such as dielectric heating treatment, induction heating treatment, ultrasonic welding treatment, or laser welding treatment have been proposed.

[0003] The bonding method when using glass as the adherend includes the techniques described below.

[0004] For example, in Patent Document 1, a thermoplastic resin composition for bonding glass to an inorganic reinforced thermoplastic resin is described, which contains a heating element that generates heat under high-frequency induction and a thermoplastic resin with a melting point of 90°C to 200°C. The thermoplastic resin is modified using a monomer containing functional groups that react with inorganic substances in the presence of moisture.

[0005] For example, Patent Document 2 describes a dielectric heating adhesive film for bonding various adherends made of the same or different materials, the dielectric heating adhesive film comprising a polyolefin resin having polar sites and dielectric fillers in a given proportion.

[0006] In addition, as another bonding method, for example, Patent Document 3 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 olefinic unsaturated silane compound with low-density polyethylene.

[0007] Existing technical documents

[0008] Patent documents

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

[0010] Patent Document 2: International Publication No. 2018 / 147352

[0011] Patent Document 3: Japanese Patent Application Publication No. 2016-068426 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] When using the thermoplastic resin composition described in Patent Document 1, the energy required for bonding with glass is high, and when using the glass bonding sheet described in Patent Document 3, the pressure holding time required for vacuum lamination for bonding with glass is long.

[0014] Although glass material is also described as an example of an adherend in Patent Document 2, it is difficult to obtain sufficient adhesion strength to glass material for the dielectric heating adhesive film described in Patent Document 2.

[0015] The purpose of this invention is to provide a high-frequency dielectric heating adhesive sheet that can bond to glass with high adhesive strength even with low energy consumption.

[0016] Problem Solving Methods

[0017] According to one aspect of the present invention, a high-frequency dielectric heating adhesive sheet can be provided, having an adhesive layer comprising at least a thermoplastic resin (A) and a dielectric material that generates heat upon application of a high-frequency electric field.

[0018] The adhesive layer described above contains a silane-modified polyolefin, which is the thermoplastic resin (A) described above.

[0019] The MFR of the above thermoplastic resin (A) at 190°C is more than 2 g / 10 min and less than 50 g / 10 min.

[0020] In one embodiment of the high-frequency dielectric heating adhesive sheet of the present invention, the softening temperature of the high-frequency dielectric heating adhesive sheet is preferably 50°C or higher.

[0021] In one embodiment of the high-frequency dielectric heating adhesive sheet of the present invention, it is preferable that the storage modulus of the high-frequency dielectric heating adhesive sheet at 20°C is 5 MPa or more.

[0022] In one aspect of the high-frequency dielectric heating adhesive sheet of the present invention, it is preferable that the peak temperature of the loss tangent of the high-frequency dielectric heating adhesive sheet is below 30°C.

[0023] In one aspect of the high-frequency dielectric heating adhesive sheet of the present invention, it is preferable that the volume content of the dielectric material in the adhesive layer is 5% or more and 50% or less.

[0024] In one embodiment of the high-frequency dielectric heating adhesive sheet of the present invention, the dielectric material is preferably dielectric filler (B).

[0025] In one aspect of the high-frequency dielectric heating adhesive sheet of the present invention, the dielectric filler (B) preferably comprises at least one selected from zinc oxide, silicon carbide, barium titanate and titanium oxide.

[0026] In one aspect of the high-frequency dielectric heating adhesive sheet of the present invention, it is preferable that the volume average particle size of the dielectric filler (B) is 1 μm or more and 30 μm or less, and the volume average particle size is determined by measuring the particle size distribution of the dielectric filler (B) by laser diffraction / scattering method, and calculated based on the particle size distribution measurement result and JIS Z 8819-2:2001.

[0027] In one embodiment of the high-frequency dielectric heating adhesive sheet of the present invention, the thickness of the high-frequency dielectric heating adhesive sheet is preferably 5 μm or more.

[0028] According to one aspect of the invention, a high-frequency dielectric heating adhesive sheet can be provided that can bond to glass with high adhesive strength even with low energy consumption. Attached Figure Description

[0029] Figure 1A This is a cross-sectional schematic diagram of a high-frequency dielectric heating adhesive sheet according to one embodiment.

[0030] Figure 1B This is a cross-sectional schematic diagram of a high-frequency dielectric heating adhesive sheet according to one embodiment.

[0031] Figure 1C This is a cross-sectional schematic diagram of a high-frequency dielectric heating adhesive sheet according to one embodiment.

[0032] Figure 2 This is a schematic diagram illustrating the high-frequency dielectric heating process using a high-frequency dielectric heating adhesive sheet and a dielectric heating device according to one embodiment.

[0033] Figure 3A This is a diagram used to illustrate the evaluation of the wetting and spreading properties of a film.

[0034] Figure 3B This is a diagram used to illustrate the evaluation of the wetting and spreading properties of a film.

[0035] Figure 3C This is a diagram used to illustrate the evaluation of the wetting and spreading properties of a film.

[0036] Symbol Explanation

[0037] 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 adhesive device, 51…first high-frequency electric field applying electrode, 52…second high-frequency electric field applying electrode, 53…high-frequency power supply, AS1…adhesive sheet, WK1…adhend, WK2…adhend. Detailed Implementation

[0038] [High-frequency dielectric heating adhesive sheet]

[0039] The high-frequency dielectric heating adhesive sheet of this embodiment has an adhesive layer containing at least a thermoplastic resin (A) and a dielectric material that heats up when a high-frequency electric field is applied. The adhesive layer contains a silane-modified polyolefin as the thermoplastic resin (A), and the medium-frequency filtration rate (MFR) of the thermoplastic resin (A) at 190°C is 2 g / 10 min or more and 50 g / 10 min or less. A high-frequency electric field refers to an electric field whose direction is reversed at high frequencies.

[0040] The dielectric material is a material that generates heat when a high-frequency electric field is applied, preferably a material that generates heat when a high-frequency electric field with a frequency range of 3 MHz or higher and 300 MHz or lower is applied. The dielectric material is preferably at least one of a dielectric resin and a dielectric filler. From the viewpoint that it is easier to suppress the deterioration of the dielectric material contained in the high-frequency dielectric heating adhesive sheet during processing, the dielectric filler (B) is more preferably used as the dielectric material.

[0041] The following description addresses the case where the high-frequency dielectric heating adhesive sheet of this embodiment includes dielectric filler (B) as the dielectric material.

[0042] <Thermoplastic Resin (A)>

[0043] The adhesive layer contains one or more thermoplastic resins (A), and at least contains a silane-modified polyolefin as the thermoplastic resin (A).

[0044] (MFR of thermoplastic resins)

[0045] The thermoplastic resin (A) has an MFR of 2 g / 10 min or more at 190°C, preferably 2.5 g / 10 min or more, and more preferably 3 g / 10 min or more.

[0046] The thermoplastic resin (A) has an MFR of 50 g / 10 min or less at 190°C, preferably 30 g / 10 min or less, and more preferably 20 g / 10 min or less.

[0047] By setting the MFR of thermoplastic resin (A) at 190°C to 2 g / 10 min or more, it exhibits excellent sheet forming properties and good wetting and spreading of the adhesive layer during bonding, thus easily achieving bond strength in a short time.

[0048] By keeping the MFR of the thermoplastic resin (A) below 50 g / 10 min at 190°C, it is easy to prevent the viscosity of the adhesive layer from becoming too low during dielectric heat treatment. When the viscosity of the adhesive layer becomes too low, it will lead to a reduction in the amount of resin between the adhered objects during bonding, making it difficult to obtain adhesive strength. However, by suppressing the decrease in viscosity, adhesive strength can be easily obtained.

[0049] When the adhesive layer contains only silane-modified polyolefin as thermoplastic resin (A), the MFR of the silane-modified polyolefin at 190°C meets the range of the MFR of the thermoplastic resin (A) at 190°C.

[0050] 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 of the thermoplastic resin mixture in the adhesive layer at 190°C satisfies the range of the MFR of the thermoplastic resin (A) at 190°C described above.

[0051] The MFR of thermoplastic resin (A) at 190°C can be determined by the method described in the items of the examples described later.

[0052] (Silane-modified polyolefin)

[0053] There are no particular limitations on silane-modified polyolefins, but they are preferably selected from at least one of the following: copolymers of silane-containing compounds and olefins, and silane-modified polyolefins obtained by graft polymerization of polyolefins containing silane-containing compounds.

[0054] The olefin copolymerized with the silyl-containing compound is preferably an α-olefin having 2 to 20 carbon atoms, for example. The α-olefin having 2 to 20 carbon atoms is preferably selected from at least one olefin chosen 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, more preferably from at least one olefin chosen from ethylene and propylene. The olefin copolymerized with the silyl-containing compound may be one or more olefins.

[0055] Examples of polyolefins that are grafted using silyl-containing compounds include homopolymers of the aforementioned olefins and copolymers of two or more olefins. Homopolymers or copolymers having monomer units derived from at least one of olefins, ethylene and propylene, are preferred. Furthermore, silane-modified polyolefins obtained by grafting a polyolefin having reactive groups using a silyl-containing compound are also preferred.

[0056] Examples of silyl-containing compounds include: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, vinyltricarboxylic acid silane, vinyltriacetylsilane, vinyltrichlorosilane, vinyltrimethylethyl ketoxime silane, vinyltriisopropoxysilane, and vinylmethyldimethoxysilane, etc.; (meth)acryloyloxymethyltrimethoxysilane and other (meth)acryloylsilanes; styrylylsilanes such as styryltrimethoxysilane, etc. It should be noted that in this specification, "(meth)acrylic acid" is used to refer to both "acrylic acid" and "methacrylic acid," and the same applies to other similar terms.

[0057] (Other thermoplastic resins)

[0058] As long as it is within the scope of achieving the purpose of this invention, the adhesive layer may also contain other thermoplastic resins different from silane-modified polyolefins, and there are no particular restrictions on other thermoplastic resins.

[0059] When the adhesive layer contains a mixture of silane-modified polyolefins and other thermoplastic resins as thermoplastic resins, the viscosity of the adhesive layer can be easily adjusted, making it easy to adapt to the processing of high-frequency dielectric heating adhesive sheets. In addition, since unwanted cross-linking reactions can be suppressed, it is easy to prevent the degradation of adhesive strength over time.

[0060] When the adhesive layer contains silane-modified polyolefin as the main component of thermoplastic resin, the adhesive layer can easily achieve high adhesion to glass.

[0061] When the adhesive layer contains silane-modified polyolefin and other thermoplastic resins, the content of silane-modified polyolefin in the thermoplastic resin (A) of 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. Furthermore, the content of silane-modified polyolefin in the thermoplastic resin (A) of the adhesive layer is preferably 100% by volume or less.

[0062] With regard to other thermoplastic resins, for example from the viewpoint of easy melting and having given heat resistance, it is preferred to select at least one 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.

[0063] In this specification, the term "other thermoplastic resins" refers to polyolefin resins, including polyolefin resins with polar sites and polyolefin resins without polar sites, and is different from silane-modified polyolefins. Where the presence or absence of polar sites in a polyolefin resin is to be specifically specified, it will be described as either polyolefin resins with polar sites or polyolefin resins without polar sites.

[0064] The adhesive layer preferably further contains a polyolefin resin with polar sites as a thermoplastic resin (A), and the polyolefin resin with polar sites is preferably an acid-modified polyolefin resin.

[0065] When the adhesive layer contains silane-modified polyolefin and polyolefin resin with polar sites, the volume ratio of silane-modified polyolefin and polyolefin resin with polar sites 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.

[0066] (Polyolefin resins)

[0067] When the adhesive layer contains a polyolefin resin as a thermoplastic resin (A), examples of such polyolefin resins include: 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. The polyolefin resin as thermoplastic resin (A) can be a single resin or a combination of two or more resins.

[0068] (Polyolefin resins with polar sites)

[0069] In polyolefin resins with polar sites, there are no particular limitations as long as the polar site can impart polarity to the polyolefin resin. Polyolefin resins with polar sites are preferred because they exhibit high adhesion to the adherend.

[0070] Polyolefin resins with polar sites can be copolymers of olefin monomers and monomers with polar sites. Alternatively, polyolefin resins with polar sites can be resins obtained by modifying olefin monomers by introducing polar sites through addition reactions or other methods to polymerize olefin polymers.

[0071] There are no particular restrictions on the types of olefin monomers that constitute polyolefin resins with polar sites. Examples of olefin monomers include ethylene, propylene, butene, hexene, octene, and 4-methyl-1-pentene. One of these olefin monomers can be used alone, or in combination of two or more.

[0072] From the perspective of excellent mechanical strength and stable bonding properties, olefin monomers are preferably at least one of ethylene and propylene.

[0073] The olefin-derived structural units in polyolefin resins with polar sites are preferably derived from ethylene or propylene.

[0074] Examples of polar sites include hydroxyl, carboxyl, epoxy, vinyl acetate structures, and anhydride structures. Examples of polar sites also include acid-modified structures introduced into polyolefin resins through acid modification.

[0075] The acid-modified structure, as a polar site, is a site introduced by acid modification of the thermoplastic resin (e.g., a polyolefin resin). Examples of compounds used in acid modification of the thermoplastic resin (e.g., a polyolefin resin) include unsaturated carboxylic acids, anhydrides derived from unsaturated carboxylic acids, and unsaturated carboxylic acid esters. In this specification, the polyolefin resin having the acid-modified structure is sometimes referred to as an acid-modified polyolefin resin.

[0076] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0077] Examples of anhydrides that are unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, and citraconic anhydride.

[0078] Examples of esters of unsaturated carboxylic acids include methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl itaconic acid, diethyl itaconic acid, dimethyl citrate, diethyl citrate, and dimethyl tetrahydrophthalate.

[0079] When the polyolefin resin (A) is a copolymer of an olefin monomer and a monomer having a polar site, the copolymer preferably contains 2% by mass or more structural units derived from the monomer having a polar site, more preferably 4% by mass or more, further preferably 5% by mass or more, and even more preferably 6% by mass or more. Furthermore, the copolymer preferably contains 30% by mass or less structural units derived from the monomer having a polar site, more preferably 25% by mass or less, further preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0080] By including more than 2% by mass of structural units derived from monomers with polar sites in the copolymer, the adhesive strength of the high-frequency dielectric heating adhesive sheet is improved. Furthermore, by including less than 30% by mass of structural units derived from monomers with polar sites in the copolymer, the excessive tackiness of the thermoplastic resin (A) can be prevented. As a result, it is easier to prevent the molding and processing of the high-frequency dielectric heating adhesive sheet from becoming difficult.

[0081] When the polyolefin resin (A) has an acid-modified structure, the acid-based modification rate 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.

[0082] When the polyolefin resin (A) has an acid-modified structure, the acid-based modification rate is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0083] When the thermoplastic resin (A) has an acid-modified structure, the adhesive strength of the high-frequency dielectric heating adhesive sheet is improved by making the acid-based modification rate 0.01% by mass or more. Furthermore, by making the acid-based modification rate 30% by mass or less, the excessive tackiness of the thermoplastic resin (A) can be prevented. As a result, it is easier to prevent the molding and processing of the high-frequency dielectric heating adhesive sheet from becoming difficult.

[0084] In this specification, the acid-based modification rate refers to the percentage of the mass of the acid-derived portion relative to the total mass of the acid-modified polyolefin.

[0085] (Maleic anhydride modified polyolefin)

[0086] The polyolefin resin (A) is more preferably an acid anhydride structure as an acid-modified structure. The acid anhydride structure is more preferably a maleic anhydride structure. The maleic anhydride structure can be a group introduced by grafting modification of the thermoplastic resin, or it can be a maleic anhydride copolymer obtained by copolymerizing monomers containing the maleic anhydride structure.

[0087] In maleic anhydride-modified polyolefins, the modification rate based on maleic anhydride is preferably in the same range as the modification rate when the polyolefin resin (A) has an acid-modified structure, and the effect obtained within this range is also the same as when the polyolefin resin (A) has an acid-modified structure.

[0088] When the maleic anhydride-modified polyolefin is a copolymer containing an olefin monomer and a monomer with a maleic anhydride structure, the proportion of structural units derived from the monomer containing the maleic anhydride structure in the copolymer is preferably in the same range as the proportion of structural units derived from the monomer with a polar site in the copolymer of an olefin monomer and a monomer with a polar site. The effect obtained within this range is also the same as when the polyolefin resin (A) is a copolymer of an olefin monomer and a monomer with a polar site.

[0089] The olefin-derived structural units in maleic anhydride-modified polyolefins are preferably derived from ethylene or propylene. That is, maleic anhydride-modified polyolefins are preferably maleic anhydride-modified polyethylene resins or maleic anhydride-modified polypropylene resins.

[0090] When the adhesive layer contains silane-modified polyolefin as the thermoplastic resin (A) and acid-modified resin as another thermoplastic resin, the acid-modified resin also has good adhesion to glass. Therefore, even if the proportion of silane-modified polyolefin in the adhesive layer decreases, the reduction in adhesive strength is easily suppressed. When the adhesive layer contains silane-modified polyolefin and acid-modified resin as the thermoplastic resin (A), the total volume content of silane-modified polyolefin and 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.

[0091] <Dielectric Filler (B)>

[0092] Dielectric filler (B) is a filler that generates heat by applying a high-frequency electric field.

[0093] The dielectric filler (B) is preferably a filler that heats up when a high-frequency electric field with a frequency range of 3 MHz or higher and 300 MHz or lower is applied. The dielectric filler (B) is preferably a filler that heats up when a high-frequency electric field with a frequency range of 3 MHz or higher and 300 MHz or lower is applied, for example, frequencies such as 13.56 MHz, 27.12 MHz, or 40.68 MHz.

[0094] (type)

[0095] The dielectric filler (B) is suitable as one or a combination of two or more of the following materials: zinc oxide, silicon carbide (SiC), anatase titanium oxide, barium titanate, barium zirconate titanate, lead titanate, potassium niobate, rutile titanium oxide, hydrated aluminum silicate, hydrated aluminosilicates of alkali metals, or hydrated aluminosilicates of alkaline earth metals.

[0096] The dielectric filler (B) preferably comprises at least one selected from zinc oxide, silicon carbide, barium titanate and titanium oxide.

[0097] Among the dielectric fillers described, zinc oxide is further preferred as it offers a wide variety of types, shapes, and sizes, and can be used to improve the bonding and mechanical properties of the high-frequency dielectric heating adhesive sheet to suit various applications. By using zinc oxide as the dielectric filler (B), a colorless high-frequency dielectric heating adhesive sheet can be obtained. Zinc oxide has a low density among dielectric fillers; therefore, when bonding adhered objects using a high-frequency dielectric heating adhesive sheet containing zinc oxide as the dielectric filler (B), the total weight of the bond is less likely to increase compared to using sheets containing other dielectric fillers. Zinc oxide has relatively low hardness in ceramics, thus minimizing damage to the manufacturing apparatus for the high-frequency dielectric heating adhesive sheet. Since zinc oxide is a non-reactive oxide, it causes minimal damage to the thermoplastic resin, even when combined with it.

[0098] Furthermore, the titanium oxide used as dielectric filler (B) is preferably at least one of anatase titanium oxide and rutile titanium oxide, and from the viewpoint of excellent dielectric properties, anatase titanium oxide is more preferred.

[0099] (volume content)

[0100] The volume content of dielectric filler (B) in the adhesive layer is preferably 5% or more, more preferably 8% or more, and even more preferably 10% or more.

[0101] The volume content of dielectric filler (B) in the adhesive layer is preferably 50% or less, more preferably 40% or less, further preferably 35% or less, and even more preferably 25% or less.

[0102] By increasing the volume content of dielectric filler (B) in the adhesive layer to 5% or more, the thermal properties are improved, making it easier to firmly bond the adhesive layer to the glass substrate.

[0103] By ensuring that the volume content of dielectric filler (B) in the adhesive layer is below 50% by volume, it is easy to obtain flexibility when fabricating the sheet and it is also easy to prevent a decrease in toughness. Therefore, it is easy to process the high-frequency dielectric heating adhesive sheet into the desired shape in subsequent processes.

[0104] It should be noted that, since the high-frequency dielectric heating adhesive sheet of this embodiment contains thermoplastic resin (A) and dielectric filler (B), the volume content of dielectric filler (B) relative to the total volume of thermoplastic resin (A) and 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 dielectric filler (B) relative to the total volume of thermoplastic resin (A) and 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.

[0105] In the above description, the volume content of the dielectric material in the adhesive layer was explained with respect to the case where the dielectric material is dielectric filler (B). However, the volume content of the dielectric material in the adhesive layer is not limited to the case where the dielectric material is dielectric filler (B). It is also suitable to have a volume content in the same range as that of dielectric filler (B) in the adhesive layer when the dielectric material is other than dielectric filler (B). That is, the volume content of the dielectric material in the adhesive layer is preferably 5% by volume or more, and preferably 50% by volume or less.

[0106] (Average particle size)

[0107] 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.

[0108] 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.

[0109] By making the volume average particle size of the dielectric filler (B) greater than 1 μm, the high-frequency dielectric heating adhesive sheet exhibits high heating performance when a high-frequency electric field is applied, and the adhesive layer can be strongly bonded to the glass substrate in a short time.

[0110] By making the volume average particle size of the dielectric filler (B) less than 30 μm, the high-frequency dielectric heating adhesive sheet exhibits high heating performance when a high-frequency electric field is applied, and the adhesive layer can be strongly bonded to the glass substrate in a short time. In addition, by making the volume average particle size of the dielectric filler (B) less than 30 μm, the strength reduction of the high-frequency dielectric heating adhesive sheet can be prevented.

[0111] The volume average particle size of the dielectric filler (B) can be determined by the following method: the particle size distribution of the dielectric filler (B) is determined by laser diffraction / scattering, and the volume average particle size is calculated based on the results of the particle size distribution determination and JIS Z 8819-2:2001.

[0112] In the high-frequency dielectric heating adhesive sheet of this embodiment, the average particle size D of the dielectric filler (B) is preferably [missing information]. F The thickness T of the adhesive layer satisfies 1 ≤ T / D F Relationships ≤2500.

[0113] T / D F Preferably 1 or more, preferably 2 or more, preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. T / D F When the value is 1 or higher, it can prevent the reduction of adhesive strength caused by the contact between the dielectric filler (B) and the adherend during bonding.

[0114] T / D F Preferably, it is 2500 or less; more preferably, 2000 or less; more preferably, 1750 or less; even more preferably, 1000 or less; further preferably, 500 or less; even more preferably, 100 or less; and even more preferably, 50 or less. T / D F When the value is below 2500, it can suppress the burden on the sheet manufacturing equipment when making high-frequency dielectric heating bonding sheets.

[0115] (additive)

[0116] The high-frequency dielectric heating adhesive sheet of this embodiment may or may not contain additives. When the high-frequency dielectric heating adhesive sheet of this embodiment is composed of multiple layers, at least any one of the multiple layers may or may not contain additives. When at least any one of the multiple layers contains additives, the adhesive layer may or may not contain additives.

[0117] When the high-frequency dielectric heating adhesive sheet of this embodiment contains additives, examples of such additives include: tackifiers, plasticizers, waxes, colorants, antioxidants, ultraviolet absorbers, antibacterial agents, coupling agents, viscosity modifiers, organic fillers, and inorganic fillers. The organic and inorganic fillers used as additives differ from the dielectric material (dielectric filler).

[0118] Tackifiers and plasticizers can improve the melting and bonding properties of high-frequency dielectric heating adhesive sheets.

[0119] Examples of tackifiers include: rosin derivatives, polyterpene resins, aromatic modified terpene resins, hydrides of aromatic modified terpene resins, terpene phenol resins, coumarone-indene resins, aliphatic petroleum resins, aromatic petroleum resins, and hydrides of aromatic petroleum resins.

[0120] Examples of plasticizers include: petroleum-based processed oils, natural oils, dialkyl diacid esters, and low molecular weight liquid polymers. Examples of petroleum-based processed oils include: paraffin-based processed oils, cycloalkane-based processed oils, and aromatic-based processed oils. Examples of natural oils include: castor oil and tall oil. Examples of dialkyl diacid esters include: dibutyl phthalate, dioctyl phthalate, and dibutyl adipate. Examples of low molecular weight liquid polymers include: liquid polybutene and liquid polyisoprene.

[0121] When the high-frequency dielectric heating adhesive sheet of this embodiment contains additives, the content of additives 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. Furthermore, the content of additives 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.

[0122] The high-frequency dielectric heating adhesive sheet of this embodiment preferably does not contain solvents. When using a solvent-free high-frequency dielectric heating adhesive sheet, the problem of VOCs (Volatile Organic Compounds) caused by the adhesive used to bond with the adhered object is less likely to occur.

[0123] The adhesive layer of the high-frequency dielectric heating adhesive sheet in this embodiment preferably does not contain carbon or carbon compounds with carbon as the main component (e.g., carbon black) and conductive materials 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 alloys, iron-nickel-chromium alloys, carbon fibers, and carbon black.

[0124] When the adhesive layer contains a conductive material, the content of the conductive material in the adhesive layer is preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.1% by mass or less, based independently on the total amount of the adhesive layer.

[0125] The content of conductive material in the adhesive layer is particularly preferably 0% by mass.

[0126] When the content of conductive material in the adhesive layer is less than 20% by mass, it is easy to prevent the electrical insulation breakdown that could lead to carbonization of the adhesive and the adhered material during dielectric heating treatment.

[0127] The total content of thermoplastic resin (A) and dielectric filler (B) in the adhesive layer of the high-frequency dielectric heating adhesive sheet of this embodiment is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 99% by mass or more.

[0128] As one embodiment of the high-frequency dielectric heating adhesive sheet, it is composed of only one layer of adhesive with high-frequency dielectric adhesion. It should be noted that the high-frequency dielectric heating adhesive sheet of the present invention is not limited to being composed of only one layer of adhesive; other embodiments of the high-frequency dielectric heating adhesive sheet may include forms with layers other than the adhesive layer stacked on top of it.

[0129] In this way, high-frequency dielectric heating adhesive sheets sometimes consist of only one layer of high-frequency dielectric adhesive layer. Therefore, in this specification, the terms "high-frequency dielectric heating adhesive sheet" and "adhesive layer" can be used interchangeably in some cases.

[0130] Figures 1A to 1C Schematic diagrams illustrating various forms of the high-frequency dielectric heating adhesive sheet of this embodiment are provided.

[0131] Figure 1A The high-frequency dielectric heating adhesive sheet 1A shown consists 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.

[0132] The high-frequency dielectric heating adhesive sheet preferably consists of only a single adhesive layer. By consisting of only a single adhesive layer, the thickness of the high-frequency dielectric heating adhesive sheet can be reduced, and it can be easily molded.

[0133] 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 to any component capable of supporting the adhesive layer 10; examples include resin films or resin sheets containing at least one resin selected from polyolefin resins such as polyethylene resin and polypropylene resin, polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin, acetate resins, ABS resin, polystyrene resin, and vinyl chloride resin. The substrate 30 may also contain a dielectric filler (B), which may be the same as or different from the dielectric filler in the substrate 30.

[0134] Figure 1CThe 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. Sometimes the adhesive layer 10 in the high-frequency dielectric heating adhesive sheet 1C is referred to as the first adhesive layer, and sometimes the adhesive layer 20 is referred to as the second adhesive layer. In a high-frequency dielectric heating adhesive sheet configured with an intermediate layer disposed between the first adhesive layer and the second adhesive layer, as long as the first adhesive layer meets the conditions of the adhesive layer of the high-frequency dielectric heating adhesive sheet of this embodiment, it is acceptable. In one embodiment, the first adhesive layer and the second adhesive layer are layers with the same composition and characteristics. In another 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 composition and characteristics. In yet another embodiment, the second adhesive layer is a layer of a general adhesive that is not a high-frequency dielectric heating adhesive layer. For example, a layer of a drying-curing type adhesive that dries and solidifies due to the evaporation of water or solvent, or a layer of an adhesive formed by an adhesive (pressure-sensitive adhesive).

[0135] <Morphology and Characteristics of High-Frequency Dielectric Heating Adhesive Sheets>

[0136] In one embodiment, the high-frequency dielectric heating adhesive sheet consists of only one adhesive layer; in another embodiment, it may consist of multiple layers. When the high-frequency dielectric heating adhesive sheet consists of only one adhesive layer, that adhesive layer itself is equivalent to the high-frequency dielectric heating adhesive sheet. Therefore, the shape and characteristics of the high-frequency dielectric heating adhesive sheet are equivalent to the shape and characteristics of the adhesive layer.

[0137] (Softening temperature)

[0138] The softening temperature of the high-frequency dielectric heating adhesive sheet in this embodiment is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher.

[0139] The softening temperature of the high-frequency dielectric heating adhesive sheet in this embodiment is preferably below 160°C, more preferably below 130°C, and even more preferably below 100°C.

[0140] By setting the softening temperature of the high-frequency dielectric heating adhesive sheet to 50°C or higher, deformation of the high-frequency dielectric heating adhesive sheet is easily suppressed when external force is applied to a joint formed by bonding glass substrates using the high-frequency dielectric heating adhesive sheet. For example, this characteristic of easily suppressing deformation of the high-frequency dielectric heating adhesive sheet is suitable for use in environments where high temperatures are easily reached. The high-frequency dielectric heating adhesive sheet with a softening temperature of 50°C or higher is suitable for applications such as those involving buildings and automobiles exposed to the outdoors.

[0141] By setting the softening temperature of the high-frequency dielectric heating adhesive sheet below 160°C, bonding strength can be easily obtained in a short time.

[0142] The softening temperature of the high-frequency dielectric heating bonded sheet can be determined by the following method. Using a descending flow tester (Shimadzu Corporation, model "CFT-100D"), under the following descending flow tester test conditions, while increasing the temperature of the test sample at a heating rate of 10°C / min, the stroke displacement velocity (mm / min) as the temperature rises is measured, and a temperature dependence graph of the stroke displacement velocity of the sample is obtained. The peak temperature obtained on the low-temperature side of this temperature dependence graph is taken as the softening temperature. The high-frequency dielectric heating bonded sheet is cut into a 3mm square sheet to obtain a test sample, and the softening temperature is determined using this test sample.

[0143] <Test Conditions for Descent Flow Tester>

[0144] • Test temperature: 190℃

[0145] • Load capacity: 5kg

[0146] • Mold: Hole shape φ2.0mm, length 5.0mm

[0147] • Barrel diameter: 11.329mm

[0148] (Energy storage modulus)

[0149] The high-frequency dielectric heating adhesive sheet of this embodiment preferably has a storage modulus of 5 MPa or more at 20°C, more preferably 10 MPa or more, and even more preferably 20 MPa or more.

[0150] The energy storage modulus of the high-frequency dielectric heating adhesive sheet in this embodiment is preferably 600 MPa or less, more preferably 400 MPa or less, further preferably 300 MPa or less, and even more preferably 200 MPa or less.

[0151] By ensuring that the energy storage modulus of the high-frequency dielectric heating adhesive sheet is above 5MPa at 20℃, the sheet will not become too soft, has self-supporting properties, and easily prevents the reduction of work efficiency when using the sheet.

[0152] By making the high-frequency dielectric heating adhesive sheet have a storage modulus of less than 600 MPa at 20°C, the sheet becomes easier to process.

[0153] The energy storage modulus of the high-frequency dielectric heating adhesive sheet at 20°C can be determined by the method described in the project of the following embodiments.

[0154] (Peak temperature of loss tangent)

[0155] The loss tangent peak temperature of the high-frequency dielectric heating adhesive sheet in this embodiment is preferably below 30°C, more preferably below 20°C, further preferably below 10°C, and even more preferably below 0°C.

[0156] The peak temperature of the loss tangent of high-frequency dielectric heating adhesive sheets is typically above -60℃.

[0157] By setting the peak loss tangent temperature of the high-frequency dielectric heating adhesive sheet to below 30°C, impact resistance in the low-temperature region can be easily obtained. Furthermore, by setting this peak loss tangent temperature to below 30°C, peeling at the interface between the adhered material and the adhesive layer caused by vibration, impact, etc., can be easily suppressed, thereby ensuring bonding strength.

[0158] The peak temperature of the loss tangent of the high-frequency dielectric heating adhesive sheet can be determined by the method described in the project of the following embodiments.

[0159] (Thickness of the high-frequency dielectric heating adhesive sheet)

[0160] The thickness of the high-frequency dielectric heating adhesive sheet in this embodiment is preferably 5 μm or more, more preferably 10 μm or more, further preferably 30 μm or more, and even more preferably 50 μm or more.

[0161] When the thickness of the high-frequency dielectric heating adhesive sheet is 5μm or more, it can easily follow the contours of the adhered object and exhibit strong adhesion when bonding with the object.

[0162] 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 even more preferably 50 μm or more.

[0163] When the high-frequency dielectric heating adhesive sheet is a multilayer structure sheet, if the thickness of the adhesive layer is 5μm or more, the adhesive layer can easily follow the unevenness of the adhered object when bonding with the adhered object, and can easily show the bonding strength.

[0164] There is no particular upper limit to the thickness of the high-frequency dielectric heating adhesive sheet. However, as the thickness of the high-frequency dielectric heating adhesive sheet increases, the overall weight of the bonded assembly also increases. Therefore, the thickness of the high-frequency dielectric heating adhesive sheet is preferably within a range that is not problematic in practical use. Considering both the practicality and moldability of the high-frequency dielectric heating adhesive sheet, its thickness is preferably 2000 μm or less, more preferably 1000 μm or less, and even more preferably 600 μm or less.

[0165] (Manufacturing method of high frequency dielectric heating adhesive sheet)

[0166] Single-layer high-frequency dielectric heating adhesive sheets can be manufactured by premixing the above-mentioned components, mixing them using known mixing equipment such as extruders and hot rollers, and using known molding methods such as extrusion molding, calendering, injection molding, and casting molding.

[0167] When the high-frequency dielectric heating adhesive sheet of this embodiment has a multilayer structure, it can be manufactured, for example, by premixing the above-mentioned components and co-extruding them using a multilayer extruder. Alternatively, a multilayer sheet can be manufactured by separately fabricating single-layer sheets of each layer constituting the high-frequency dielectric heating adhesive sheet of this embodiment (e.g., the first adhesive layer, the intermediate layer, and the second adhesive layer) and laminating multiple single-layer sheets to stack them. When laminating multiple single-layer sheets, a hot laminator can be used, for example.

[0168] 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 the molten adhesive layer onto the substrate, or by wet coating of the coating liquid obtained by dispersing or dissolving the adhesive layer composition in a solvent onto the substrate.

[0169] (How to use high-frequency dielectric heating adhesive sheet)

[0170] The high-frequency dielectric heating adhesive sheet of this embodiment can be used for bonding with the substrate. Furthermore, the high-frequency dielectric heating adhesive sheet of this embodiment can also be used for bonding various substrates together.

[0171] There are no special restrictions on the material of the adherend. The material of the adherend can be any material from organic and inorganic materials (including metals, etc.), or it can be a composite material of organic and inorganic materials.

[0172] Organic materials that can be used as the adherend can include, for example, plastic 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 (nylon 6 and nylon 66, etc.), polyester resin (polyethylene terephthalate (PET resin) and polybutylene terephthalate resin (PBT resin), etc.), polyacetal resin (POM resin), polymethyl methacrylate resin, and polystyrene resin, etc. Examples of rubber materials include: styrene-butadiene rubber (SBR), ethylene propylene rubber (EPR), and silicone rubber, etc. Additionally, the adherend can also be a foamed organic material.

[0173] Inorganic materials that can be used as the adherend can include glass, cement, ceramics, and metals. Alternatively, the adherend can be fiber-reinforced plastics (FRP), a composite material of fibers and the aforementioned plastic materials. The plastic material in the fiber-reinforced resin can be, 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), etc.), polyacetal resin (POM resin), polymethyl methacrylate resin, and polystyrene resin, etc. The fibers in the fiber-reinforced resin can include, for example, glass fibers, Kevlar fibers, and carbon fibers.

[0174] When using the high-frequency dielectric heating adhesive sheet of this embodiment to bond multiple objects together, the multiple objects may be made of the same material or different materials.

[0175] The high-frequency dielectric heating adhesive sheet of this embodiment is suitable for bonding with glass substrates. When bonding multiple substrates to each other, if at least one substrate is made of glass, the high-frequency dielectric heating adhesive sheet of this embodiment can strongly bond to the glass substrate.

[0176] The shape of the adherend is not particularly limited, but it is preferable to have a surface that allows the high-frequency dielectric heating adhesive sheet to adhere, and it is preferably sheet-like or plate-like. When multiple adherends are bonded together, these adherends may have the same shape and different dimensions.

[0177] [Adhesion Method]

[0178] The bonding method of this embodiment is a bonding method using the high-frequency dielectric heating adhesive sheet of this embodiment.

[0179] Hereinafter, as an example of the bonding method of this embodiment, an example will be given of bonding the first adherend and the second adherend using a high-frequency dielectric heating adhesive sheet consisting of a single adhesive layer. However, the present invention is not limited to this method. The material of the second adherend is also not particularly limited.

[0180] One aspect of the bonding method in this embodiment includes the following steps P1 and P2.

[0181] Process P1

[0182] Step P1 is the process of sandwiching the high-frequency dielectric heating adhesive sheet of this embodiment between the first adherend and the second adherend. In step P1, the first glass adherend is brought into contact with the first surface of the high-frequency dielectric heating adhesive sheet. Additionally, in step P1, the second adherend is brought into contact with the second surface of the high-frequency dielectric heating adhesive sheet.

[0183] A high-frequency dielectric heating adhesive sheet only needs to be sandwiched between the first and second adherends in a manner that allows them to bond. The high-frequency dielectric heating adhesive sheet can be sandwiched between a portion, multiple portions, or the entire surface of the first and second adherends. From the viewpoint of improving the adhesive strength between the first and second adherends, it is preferable to sandwich the high-frequency dielectric heating adhesive sheet with the entire adhesive surface of the first and second adherends. Alternatively, as a method of sandwiching the high-frequency dielectric heating adhesive sheet between a portion of the first and second adherends, one example is to arrange the high-frequency dielectric heating adhesive sheet in a frame shape along the outer periphery of the adhesive surface of the first and second adherends and sandwich it between the first and second adherends. By arranging the high-frequency dielectric heating adhesive sheet in a frame shape in this way, the adhesive strength between the first and second adherends can be obtained, and compared to the case where the high-frequency dielectric heating adhesive sheet is arranged on the entire adhesive surface, the joint can be made lighter. Furthermore, by using a method that sandwiches a portion of the high-frequency dielectric heating adhesive sheet between the first and second adherends, the size of the high-frequency dielectric heating adhesive sheet used can be reduced, thus shortening the high-frequency dielectric heating process time compared to the case where the high-frequency dielectric heating adhesive sheet is disposed over the entire bonding surface.

[0184] Process P2

[0185] Step P2 is a step in which a high-frequency electric field of 3MHz or more and 300MHz or less is applied to the high-frequency dielectric heating adhesive sheet sandwiched between the first and second adherends in step P1, and the first and second adherends are bonded together using the high-frequency dielectric heating adhesive sheet.

[0186] For example, a high-frequency electric field can be applied to a high-frequency dielectric heating adhesive sheet using a dielectric heating bonding device. It should be noted that in this specification, the term "dielectric heating device" is sometimes referred to as "dielectric heating bonding device" or "high-frequency dielectric heating device".

[0187] Figure 2 A schematic diagram illustrating the high-frequency dielectric heating process of the high-frequency dielectric heating adhesive sheet and dielectric heating device using this embodiment is shown.

[0188] (Dielectric heating bonding device)

[0189] Figure 2 A schematic diagram of the dielectric heating bonding device 50 is shown.

[0190] 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.

[0191] 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. Using this 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.

[0192] In the case where a pair of flat plates are configured such that the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52 are parallel to each other, such an electrode configuration is sometimes referred to as a parallel flat plate type.

[0193] The application of a high-frequency electric field is preferably performed using a parallel-plate type high-frequency dielectric heating device. When using a parallel-plate type high-frequency dielectric heating device, the high frequency penetrates the high-frequency dielectric heating adhesive sheet located between the electrodes, thus enabling the entire high-frequency dielectric heating adhesive sheet to be heated, allowing the adhered material and the high-frequency dielectric heating adhesive sheet to be bonded in a short time.

[0194] The high-frequency power supply 53, used to apply a high-frequency electric field, for example, at 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, respectively.

[0195] like Figure 2 As shown, the dielectric heating bonding apparatus 50 performs dielectric heating treatment using a high-frequency dielectric heating bonding sheet 1A sandwiched between the first adherend 110 and the second adherend 120. In addition to dielectric heating treatment, the dielectric heating bonding apparatus 50 also bonds the first adherend 110 and the second adherend 120 by applying pressure using a first high-frequency electric field application electrode 51 and a second high-frequency electric field application electrode 52. It should be noted that the first adherend 110 and the second adherend 120 can also be bonded together without applying pressure.

[0196] When a high-frequency electric field is applied between the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52, the dielectric filler (not shown) dispersed in the adhesive component in the high-frequency dielectric heating adhesive sheet 1A will absorb high-frequency energy.

[0197] The dielectric filler functions as a heat source, melting the thermoplastic resin component through its heating. Even with short-term processing, it can ultimately bond the first adherend 110 and the second adherend 120 firmly together.

[0198] 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 pressurizing devices. Therefore, by applying pressure in the compression direction using the first high-frequency electric field applying electrode 51 and the second high-frequency electric field applying electrode 52, and by heating and melting the high-frequency dielectric heating adhesive sheet 1A, a stronger bond can be achieved between the first adherend 110 and the second adherend 120.

[0199] (High-frequency dielectric heating bonding conditions)

[0200] The conditions for high-frequency dielectric heating bonding can be appropriately modified, and the following conditions are preferred.

[0201] The output power of the high-frequency electric field is preferably 10W or more, more preferably 30W or more, even more preferably 50W or more, and even more preferably 80W or more.

[0202] The output power of the high-frequency electric field is preferably 50,000W or less, more preferably 20,000W or less, even more preferably 15,000W or less, even more preferably 10,000W or less, and even more preferably 1,000W or less.

[0203] When the output power of the high-frequency electric field is above 10W, it can prevent the undesirable situation of the temperature being difficult to rise during dielectric heating treatment, thus making it easy to obtain good adhesion.

[0204] When the output power of the high-frequency electric field is below 50,000W, it is easy to prevent adverse situations where temperature control becomes difficult due to dielectric heating treatment.

[0205] The application time of the high-frequency electric field is preferably more than 1 second.

[0206] 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.

[0207] When the high-frequency electric field is applied for more than 1 second, it can prevent the undesirable situation that the temperature is difficult to rise during dielectric heating treatment, thus making it easy to obtain good adhesion.

[0208] When the application time of the high-frequency electric field is less than 300 seconds, it is easy to prevent adverse situations such as reduced manufacturing efficiency, increased manufacturing cost, and thermal degradation of the adherend formed by bonding the first and second adherends.

[0209] 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.

[0210] The frequency of the applied high-frequency electric field is preferably 300MHz or less, more preferably 100MHz or less, further preferably 80MHz or less, and even more preferably 50MHz or less. Specifically, the industrial frequency bands of 13.56MHz, 27.12MHz, and 40.68MHz allocated by the International Telecommunication Union can also be used in the high-frequency dielectric heating bonding method (bonding method) of this embodiment.

[0211] (Effects of this implementation method)

[0212] According to this embodiment, the high-frequency dielectric heating adhesive sheet can be bonded to glass with high adhesive strength even with low energy consumption.

[0213] Compared to the use of adhesives that require coating, the high-frequency dielectric heating adhesive sheet of this embodiment is easier to operate and its workability when bonding with the substrate is also improved.

[0214] The high-frequency dielectric heating adhesive sheet of this embodiment has superior water resistance and moisture resistance compared to general adhesives.

[0215] The high-frequency dielectric heating adhesive sheet of this embodiment can be heated by applying a high-frequency electric field, thus allowing for localized heating. Therefore, using the high-frequency dielectric heating adhesive sheet of this embodiment, it is easy to prevent undesirable situations such as the entire adhered object melting during bonding.

[0216] According to the bonding method using the high-frequency dielectric heating adhesive sheet of this embodiment, it is possible to locally heat only a given area from the outside using a dielectric heating adhesive device. Therefore, the bonding method using the high-frequency dielectric heating adhesive sheet of this embodiment is effective even when the adhered object is a large and complex three-dimensional structure or a thick and complex three-dimensional structure, and high dimensional accuracy is required.

[0217] Furthermore, the high-frequency dielectric heating adhesive sheet according to this embodiment allows for appropriate control of its thickness and other properties. Therefore, the high-frequency dielectric heating adhesive sheet of this embodiment can be applied to roll-to-roll applications, and it can be processed into any area and shape according to the bonding area with the adhered object and the shape of the adhered object through punching or other processes. Therefore, from a manufacturing process perspective, the high-frequency dielectric heating adhesive sheet of this embodiment also has significant advantages.

[0218] [Variations on the implementation method]

[0219] This invention is not limited to the above-described embodiments. This invention may include variations and improvements within the scope of achieving the purpose of this invention.

[0220] Examples of high-frequency dielectric heating adhesive sheets that differ from the embodiments described above include the high-frequency dielectric heating adhesive sheet described below.

[0221] [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 dielectric filler (B)) 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 polyolefin, and the second thermoplastic resin (A2) is another thermoplastic resin different from the silane-modified polyolefin.

[0222] [2] In the high-frequency dielectric heating adhesive sheet of [1] above, it is preferable that the second thermoplastic resin (A2) is a resin with an acid-modified structure.

[0223] [3] In the high-frequency dielectric heating adhesive sheet of [1] or [2] above, the second thermoplastic resin (A2) is preferably a polyolefin resin with an acid-modified structure.

[0224] In the high-frequency dielectric heating adhesive sheets described above [1] to [3], the silane-modified polyolefin and other thermoplastic resins different from the silane-modified polyolefin are, for example, the resins described in the above embodiments.

[0225] When the adhesive layer is a mixture containing silane-modified polyolefin and other thermoplastic resins as thermoplastic resins, the viscosity of the adhesive layer can be easily adjusted, making it easy to provide processing adaptability for high-frequency dielectric heating adhesive sheets. In addition, since unwanted cross-linking reactions can be suppressed, it is easy to prevent the degradation of adhesive strength over time.

[0226] The high-frequency dielectric heating adhesive sheet can have an adhesive portion. By having an adhesive portion, when the high-frequency dielectric heating adhesive sheet is sandwiched between two adherends, positional shift can be prevented, allowing it to be positioned accurately. The adhesive portion can be provided on one side or both sides of the high-frequency dielectric heating adhesive sheet. Alternatively, the adhesive portion can be provided partially relative to one side of the high-frequency dielectric heating adhesive sheet. Even without the adhesive portion, the high-frequency dielectric heating adhesive sheet can strongly bond the first adherend to the second adherend.

[0227] High-frequency dielectric heating treatment is not limited to the dielectric heating bonding device with electrodes arranged opposite each other as described in the above embodiments; a lattice electrode type high-frequency dielectric heating device can also be used. The lattice electrode type high-frequency dielectric heating device has lattice electrodes 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.

[0228] For example, in the case of manufacturing a joint body formed by bonding the end of the first adherend to the end of the second adherend, a high-frequency dielectric heating device of the grid electrode type is arranged on the side of the first adherend or the side of the second adherend to apply a high-frequency electric field.

[0229] When using a grid electrode type high-frequency dielectric heating device to bond a first adherend and a second adherend, a first grid electrode can be disposed on the side of the first adherend and a second grid electrode can be disposed on the side of the second adherend, thereby sandwiching the first adherend, the high-frequency dielectric heating adhesive sheet and the second adherend between the first grid electrode and the second grid electrode and simultaneously applying a high-frequency electric field.

[0230] When using a grid electrode type high-frequency dielectric heating device to bond a first adherend and a second adherend, a grid electrode can be disposed 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 disposed on the surface side of the other of the first adherend and the second adherend and a high-frequency electric field can be applied.

[0231] The application of the high-frequency electric field is preferably performed using a lattice electrode type high-frequency dielectric heating device. By using a lattice electrode type high-frequency dielectric heating device, the adherends can be bonded together by dielectric heating from the surface side of the first and second adherends, for example, from the side of the adherend closest to the high-frequency dielectric heating adhesive sheet, regardless of the thickness of the first and second adherends. Furthermore, the use of a lattice electrode type high-frequency dielectric heating device enables energy savings in the manufacturing of the bond.

[0232] It should be noted that the diagram illustrates a method of using a dielectric heating bonding device that aligns the electrodes to each other, for the purpose of simplification.

[0233] Example

[0234] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments at all.

[0235] [Fabrication of High-Frequency Dielectric Heating Adhesive Sheets]

[0236] (Examples 1-5 and Comparative Examples 1-4)

[0237] The materials shown in Table 1 were premixed. The premixed material was fed into the hopper of a 30mm φ twin-screw extruder. The barrel temperature was set to 180°C or higher and 200°C or lower, and the die temperature was set to 200°C. The premixed material was melt-mixed. The melt-mixed material was cooled and then cut to produce granular granules. Next, the granules were fed into the hopper of a single-screw extruder equipped with a T-die. The barrel temperature and die temperature were set to 200°C. A film-like melt-mixed compound was extruded from the T-die and cooled using a cooling roller. This produced high-frequency dielectric heating adhesive sheets with a thickness of 400μm for Examples 1-5 and Comparative Examples 1-4, respectively.

[0238] The thermoplastic resins and fillers shown in Table 1 are described below.

[0239] • Silane-modified PE1: Silane-modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "LINKLONSS732N"

[0240] • Silane-modified PE2: Silane-modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "LINKLONSF800N"

[0241] • Silane-modified PP1: Silane-modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "LINKLONPM700N"

[0242] • Silane-modified PP2: Silane-modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "LINKLONPK500N"

[0243] • m-PP: Maleic anhydride modified polypropylene, manufactured by Mitsubishi Chemical Corporation, product name "MODIC P565"

[0244] • m-PE: Maleic anhydride modified polyethylene, manufactured by Mitsubishi Chemical Corporation, product name "MODIC M545"

[0245] • EVA: Ethylene-vinyl acetate copolymer, manufactured by DuPont-Mitsui Polychemical Co., Ltd., product name "EVAFLEX EV560"

[0246] • 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".

[0247] • Iron powder: Iron powder with a volume average particle size of 10 μm

[0248] (MFR: Melt Flow Rate)

[0249] The MFR of thermoplastic resin at 190°C was measured based on JIS K 7210-1:2014 and using a descending flow tester (manufactured by Shimadzu Corporation, model "CFT-100D").

[0250] In the case of using a variety of thermoplastic resins in combination, the various resins were mixed in a twin-screw extrusion process at the ratios shown in Table 1 to produce mixed resin granules, and the MFR of the mixed resin granules was measured in the same manner as described above.

[0251] (Volume average particle size of dielectric filler)

[0252] The particle size distribution of the dielectric filler was determined by laser diffraction / scattering. Based on the particle size distribution results, the volume average particle size was calculated according to JIS Z 8819-2:2001. The calculated volume average particle size of zinc oxide (ZnO) was 11 μm, and that of iron powder was 10 μm.

[0253] [Evaluation of High-Frequency Dielectric Heating Adhesive Sheets]

[0254] The high-frequency dielectric heating adhesive sheet was evaluated as described below, and the evaluation results are shown in Table 1.

[0255] (Evaluation of wetting and spreading properties)

[0256] The wetting and spreading properties of the adhesive sheet were evaluated as an indicator of high-frequency adhesion. The fabricated high-frequency dielectric heating adhesive sheet was cut into pieces measuring 13 mm × 6.5 mm. The cut pieces were then placed between a pair of soda-lime glass sheets (25 mm × 100 mm × 3 mm (thickness)) serving as the adhesive substrates. The overlapping area of ​​the soda-lime glass sheets was 25 mm × 12.5 mm = 312.5 mm². 2 Specifically, with Figure 3A The dimensions shown, and as Figure 3BGlass substrates WK1 and WK2, along with adhesive sheet AS1 (equivalent to the fabricated high-frequency dielectric heating adhesive sheet), are arranged as shown. After this arrangement, a pair of substrates and the high-frequency dielectric heating adhesive sheet are fixed between the electrodes of a high-frequency dielectric heating device (manufactured by Yamamoto Vinita, product name "YRP-400T-A"). The area of ​​each pair of electrodes in the high-frequency dielectric heating device is set to 800 mm². 2 The pair of electrodes (40mm × 20mm) are arranged to cover the overlapping portion of the substrate (soda-lime glass). While fixed, a high-frequency electric field is applied under the following high-frequency application conditions to bond the high-frequency dielectric heating adhesive sheet to the substrate.

[0257] High-frequency application conditions

[0258] Frequency: 40.68MHz

[0259] Output power: 200W

[0260] Application time: 90 seconds

[0261] Pressure: 0.5 MPa

[0262] The pressing pressure during high-frequency application is the pressure applied to the joint between the first and second adherends.

[0263] After applying a high-frequency electric field, the percentage of the area of ​​the adhesive sheet AS1 that underwent wetting and spreading relative to the area of ​​the overlapping portion of the adhered objects WK1 and WK2 (viewed from above) was measured using image analysis software. The wetting and spreading properties of the adhesive sheet were evaluated based on the following criteria: Before application, the area of ​​the adhesive sheet accounted for 27% of the area of ​​the overlapping portion of the adhered objects.

[0264] A: The area of ​​the adhesive sheet accounts for more than 80% of the area of ​​the overlapping part of the adhered objects.

[0265] B: The area of ​​the adhesive sheet accounts for more than 55% but less than 80% of the area of ​​the overlapping portion of the adhered objects.

[0266] F: The area of ​​the adhesive sheet accounts for less than 55% of the area of ​​the overlapping portion of the adhered objects.

[0267] Figure 3C The top view shows the state after the overlapping portion of the adhered material is completely filled with resin after a high-frequency electric field is applied, and resin then seeps out from the adhered material. In this case, evaluation A is given.

[0268] (Adhesive force (tensile shear force))

[0269] The high-frequency dielectric heating adhesive sheet was cut into 25mm × 12.5mm pieces and arranged to overlap with the adherend. Otherwise, an adhesive strength evaluation test piece was prepared in the same manner as described above (wetting spread evaluation). The tensile shear force (unit: MPa) was measured using this adhesive strength evaluation test piece. The tensile shear force was measured using a universal tensile testing machine (Instron 5581, manufactured by Instron Corporation). The tensile speed was set to 10mm / min. It should be noted that "not bonded" in the tensile shear force section of the table indicates that the adherend and adhesive sheet would easily peel off before the tensile shear force measurement. Additionally, "4 <" in the table indicates a tensile shear force exceeding 4 MPa.

[0270] In addition, the failure modes of test specimens were observed to evaluate the high-frequency adhesion in the determination of tensile shear force, and the adhesion was evaluated based on the following criteria. Tensile shear force was determined based on JIS K 6850:1999.

[0271] A: Coagulation failure of high-frequency dielectric heating adhesive sheets

[0272] B: Damage to the adhered substance

[0273] F: Delamination of the interface between the high-frequency dielectric heating adhesive sheet and the adherend.

[0274] (Softening temperature)

[0275] Using a descending flow tester (Shimadzu Corporation, model "CFT-100D"), under the following descending flow tester conditions, the temperature of the test sample was increased at a rate of 10°C / min, and the stroke displacement velocity (mm / min) as a function of temperature increase was measured to obtain a temperature dependence graph of the sample's stroke displacement velocity. The peak temperature obtained on the low-temperature side of this graph was taken as the softening temperature. A 3mm square sheet of test sample was obtained by cutting a high-frequency dielectric heating adhesive sheet, and the softening temperature was measured using this test sample.

[0276] <Test Conditions for Descent Flow Tester>

[0277] • Test temperature: 190℃

[0278] • Load capacity: 5kg

[0279] • Mold: Hole shape φ2.0mm, length 5.0mm

[0280] • Barrel diameter: 11.329mm

[0281] (Storage modulus and peak temperature of loss tangent)

[0282] The storage modulus E' of the high-frequency dielectric heated adhesive sheet at 20°C was obtained by viscoelasticity measurement using a dynamic viscoelasticity measuring device (Orientec Corporation, RHEOVIBRON DDV-01FP). Specifically, a high-frequency dielectric heated adhesive sheet with a sample width of 4 mm was mounted on the dynamic viscoelasticity measuring device with a measurement interval (chuck distance) of 10 mm. The viscoelasticity of the high-frequency dielectric heated adhesive sheet was measured in a tensile mode with 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 storage modulus E' of the high-frequency dielectric heated adhesive sheet at 20°C was thus obtained.

[0283] The temperature at which the tanδ (loss modulus / storage modulus) obtained in the above viscoelasticity measurement reaches its maximum is taken as the peak temperature of the loss tangent of the high-frequency dielectric heating adhesive sheet.

[0284]

[0285] According to the high-frequency dielectric heating adhesive sheet of Examples 1 to 5, glass substrates can be bonded to each other with high adhesive strength even with low energy consumption.

Claims

1. A high-frequency dielectric heating adhesive sheet having an adhesive layer with high-frequency dielectric adhesive properties, the adhesive layer containing at least a thermoplastic resin (A) and a dielectric material that generates heat by applying a high-frequency electric field. The adhesive layer does not contain conductive materials. The volume content of the dielectric material in the adhesive layer is more than 5% by volume and less than 50% by volume. The dielectric material is dielectric filler (B). The volumetric content mentioned above is the volumetric content of dielectric filler (B) relative to the total volume of thermoplastic resin (A) and dielectric filler (B). The dielectric filler (B) is zinc oxide. The adhesive layer contains a silane-modified polyolefin as the thermoplastic resin (A). The thermoplastic resin (A) has an MFR of 2 g / 10 min or more and 50 g / 10 min or less at 190°C. The aforementioned silane-modified polyolefin is selected from at least one of the following groups: copolymers of silane-containing compounds and olefins, and silane-modified polyolefins obtained by graft polymerization of polyolefins containing silane-containing compounds. The aforementioned olefin is selected from at least one olefin chosen 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. The polyolefins grafted using silyl compounds are homopolymers of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-1-pentene, 4-methyl-1-hexene, or 4,4-dimethyl-1-pentene, or copolymers of two or more of the above-mentioned olefins. The peak temperature of the loss tangent of the adhesive layer is below 30°C.

2. The high-frequency dielectric heating adhesive sheet according to claim 1, wherein, The softening temperature of the adhesive layer is above 50°C.

3. The high-frequency dielectric heating adhesive sheet according to claim 1 or 2, wherein, The adhesive layer has a storage modulus of 5 MPa or more at 20°C.

4. The high-frequency dielectric heating adhesive sheet according to claim 1 or 2, wherein, The dielectric filler (B) has a volume average particle size of 1 μm or more and 30 μm or less. The volume average particle size is determined by measuring the particle size distribution of the dielectric filler (B) using laser diffraction / scattering, and calculated based on the results of the particle size distribution measurement and JIS Z 8819-2:2001.

5. The high-frequency dielectric heating adhesive sheet according to claim 1 or 2, wherein, The thickness of the high-frequency dielectric heating adhesive sheet is 5 μm or more.

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