Heat-curable adhesive sheet

Abstract

Provided is a heat-curable adhesive sheet which includes a release liner that is adherent to the adhesive surface and that, when peeled from the adhesive surface, is easy to peel off and which has excellent handleability and is less apt to suffer protrusion of the adhesive.　The heat-curable adhesive sheet 1 has a 20°C modulus G' of 150-3,000 kPa and an 80°C modulus G' of 1 kPa or greater. The heat-curable adhesive sheet 1 preferably includes an epoxy resin (a) having an epoxy equivalent of 200-800 g / eq and a rubber-modified epoxy resin (b).

Description

Thermosetting adhesive sheet

[0001] The present invention relates to a thermosetting adhesive sheet.

[0002] In recent years, for example, to bond a metal member to another member, a thermosetting double-sided pressure-sensitive adhesive sheet that hardens when heated to exert adhesive strength and firmly bond the members together has been used. Known examples of such thermosetting adhesive sheets include adhesive sheets containing a thermosetting resin and a curing agent (see, for example, Patent Documents 1 to 3).

[0003] Double-sided adhesive sheets used to bond components together usually have release liners attached to both adhesive surfaces to protect the adhesive surfaces until use. When using the double-sided adhesive sheet, first one release liner is peeled off and the exposed adhesive surface is attached to one component, and then the other release liner is peeled off and the exposed adhesive surface is attached to the other component.

[0004] JP 2012-197427 A JP 2019-39005 A JP 7-157535 A

[0005] Although thermosetting adhesive sheets cure when heated to firmly adhere to components, many of them are soft before heat curing. For this reason, when attempting to peel off one of the release liners from a double-sided thermosetting adhesive sheet in which both adhesive surfaces are protected by release liners, there is a problem that some of the adhesive may peel off while still adhering to the release liner, causing damage to the adhesive sheet interface, a phenomenon known as "unfortunate separation."

[0006] Furthermore, when one adhesive surface of a double-sided adhesive sheet is laminated to a member and then an attempt is made to peel off the release liner laminated to the other adhesive surface, the release liner may not peel off from the adhesive surface of the adhesive sheet, and the adhesive sheet may peel off from the laminated member together with the release liner, i.e., the transferability of the adhesive sheet may be poor. For this reason, a thermosetting adhesive sheet is required to have excellent handleability and to enable the release liner to be easily peeled off from a state in which it is laminated to the adhesive surface.

[0007] Furthermore, after the thermosetting adhesive sheet is attached to a member as described above, it is heated to harden the adhesive sheet and firmly adhere it to the member. However, when the members that are adherends are attached to each other via the thermosetting adhesive sheet or when the thermosetting adhesive sheet is heated to harden, the adhesive in the adhesive sheet may flow due to pressure or heat and squeeze out from between the members, i.e., glue squeezing may occur.

[0008] For this reason, thermosetting adhesive sheets are required to have excellent handleability, allowing the release liner to be easily peeled from the adhesive surface of the adhesive sheet when the release liner is peeled off, and to be less likely to cause the adhesive to squeeze out. Note that the adhesive sheets disclosed in Patent Documents 1 to 3 do not mention having all of these properties, and there is no disclosure of a thermosetting adhesive sheet having the properties satisfied by the thermosetting adhesive sheet of the present invention described below.

[0009] The present invention was conceived under these circumstances, and its object is to provide a thermosetting adhesive sheet that is easy to handle, in which the release liner is easily peeled off from the adhesive surface of the adhesive sheet when the release liner is peeled off, and that is less likely to cause the adhesive to squeeze out.

[0010]

[0006] As a result of extensive research to achieve the above object, the present inventors have found that a thermosetting adhesive sheet having a modulus of elasticity G' at 20°C and a modulus of elasticity G' at 80°C each within a specific range makes it easy to peel the release liner from the adhesive surface when it is peeled off, provides excellent handling, and is less likely to cause adhesive extrusion. The present invention was completed based on these findings.

[0011] That is, the present invention provides a thermosetting adhesive sheet having an elastic modulus G' at 20°C of 150 to 3000 kPa and an elastic modulus G' at 80°C of 1 kPa or more.

[0012] The thermosetting adhesive sheet has an elastic modulus G' at 20°C of 150 kPa or more, which means that the sheet has an appropriate hardness near room temperature before heat curing, and therefore excellent releasability when attempting to peel one release liner from a state in which release liners are bonded to both adhesive surfaces of a double-sided adhesive sheet, and is less likely to separate, resulting in excellent handleability. Furthermore, the elastic modulus G' at 20°C of 3000 kPa or less means that the thermosetting adhesive sheet has an appropriate softness near room temperature before heat curing, and therefore excellent releasability when attempting to peel the release sheet bonded to one adhesive surface of the thermosetting adhesive sheet from a state in which one adhesive surface of the thermosetting adhesive sheet is bonded to one component, and the release liner is easily peeled along the interface with the adhesive sheet, resulting in excellent handleability.

[0013] Furthermore, since the thermosetting adhesive sheet has an elastic modulus G' of 1 kPa or more at 80°C, it has sufficient hardness before thermal curing when pressure or heat is applied, so the adhesive has low fluidity and is less likely to leak out between components.

[0014] The thermosetting adhesive sheet preferably contains an epoxy resin (a) having an epoxy equivalent of 200 to 800 g / eq and a rubber-modified epoxy resin (b).

[0015] The epoxy resin (a) is preferably at least one selected from the group consisting of bisphenol-type epoxy resins, novolac-type epoxy resins, and dimer acid-modified epoxy resins.

[0016] The mass ratio of the epoxy resin (a) to the rubber-modified epoxy resin (b) is preferably 20:80 to 80:20.

[0017] The thermosetting adhesive sheet preferably contains 0.5 to 30 parts by mass of an epoxy curing agent per 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) combined.

[0018] The epoxy curing agent contains dicyandiamide, and the content of the dicyandiamide is preferably 0.5 to 20 parts by mass per 100 parts by mass of the total of the epoxy resin (a) and the rubber-modified epoxy resin (b).

[0019] The epoxy curing agent contains a urea-based compound and / or an imidazole-based compound, and the content of the urea-based compound and / or the imidazole-based compound is preferably 1 to 10 parts by mass per 100 parts by mass of the total of the epoxy resin (a) and the rubber-modified epoxy resin (b).

[0020] The thermosetting adhesive sheet preferably contains a filler.

[0021] The average particle size of the filler is preferably 7 to 50 nm.

[0022] The specific surface area of ​​the filler per 100 g of the thermosetting adhesive sheet is 600 to 6000 m 2 It is preferable that:

[0023] The thermosetting adhesive sheet is preferably used to bond members, at least one of which is made of metal.

[0024] The thermosetting adhesive sheet is preferably used to bond metal members together or a metal member and a fiber-reinforced resin member.

[0025] The thermosetting adhesive sheet of the present invention has excellent handleability, as the release liner attached to the adhesive surface can be easily peeled off from the adhesive surface when peeled off, and the adhesive is less likely to squeeze out.

[0026] 1 is a cross-sectional view of a thermosetting adhesive sheet according to one embodiment of the present invention.

[0027] [Thermosetting Adhesive Sheet] The thermosetting adhesive sheet of the present invention has an elastic modulus G' at 20°C of 150 to 3000 kPa, and an elastic modulus G' at 80°C of 1 kPa or more.

[0028] The thermosetting adhesive sheet is preferably a double-sided adhesive sheet, and more preferably a so-called "substrate-less" double-sided adhesive sheet that does not have a substrate. Substrate-less double-sided adhesive sheets are free from problems caused by using a substrate, such as interlayer fracture with the substrate, and also have excellent conformability to the adherend. The thermosetting adhesive sheet may be used as a single layer to bond components together, or multiple layers may be stacked to form a laminate of thermosetting adhesive sheets to bond components together. Alternatively, the thermosetting adhesive sheet may be used as a single-sided adhesive sheet by laminating a substrate layer to the thermosetting adhesive sheet.

[0029] Fig. 1 is a cross-sectional schematic diagram showing one embodiment of a thermosetting adhesive sheet of the present invention. The thermosetting adhesive sheet 1 shown in Fig. 1 is a double-sided adhesive sheet. Release liners 2 and 3 are attached to both adhesive surfaces of the thermosetting adhesive sheet 1, respectively.

[0030]

[0023] As described above, the elastic modulus G' at 20°C is 150 to 3000 kPa. When the elastic modulus G' at 20°C is 150 kPa or more, the thermosetting adhesive sheet before heat curing has an appropriate hardness near room temperature, and, for example, when attempting to peel one release liner from a state in which release liners are bonded to both adhesive surfaces of a double-sided adhesive sheet, the sheet exhibits excellent releasability, is less likely to separate, and is easy to handle. When the elastic modulus G' at 20°C is 3000 kPa or less, the thermosetting adhesive sheet before heat curing has an appropriate softness near room temperature, and is easy to peel from a state in which one adhesive surface of the thermosetting adhesive sheet is bonded to one member and the release sheet bonded to the other adhesive surface is peeled off, the release liner is easily peeled along the interface with the adhesive sheet, and is easy to handle.

[0031] The elastic modulus G' at 20° C. is preferably 200 kPa or more, more preferably 250 kPa or more, and the elastic modulus G' at 20° C. is preferably 2000 kPa or less, more preferably 900 kPa or less.

[0032] As described above, the thermosetting adhesive sheet of the present invention has an elastic modulus G' of 1 kPa or more at 80° C. Because the elastic modulus G' at 80° C. is 1 kPa or more, the thermosetting adhesive sheet before thermal curing has sufficient hardness when pressure or heat is applied, so the fluidity of the adhesive is low and the adhesive is less likely to squeeze out between members.

[0033] The elastic modulus G' at 80°C is preferably 3 kPa or more, more preferably 7 kPa or more, and even more preferably 10 kPa or more. The elastic modulus G' at 80°C is preferably 500 kPa or less, more preferably 300 kPa or less, and even more preferably 200 kPa or less. When the elastic modulus G' at 80°C is 500 kPa or less (particularly 200 kPa or less), the adhesive has excellent conformability to the irregularities of the adherend and excellent shear adhesive strength.

[0034] The elastic modulus G' at 20°C and the elastic modulus G' at 80°C are the elastic moduli G' of the thermosetting adhesive sheet before thermal curing. The elastic modulus G' is determined as the storage modulus at 20°C or 80°C by dynamic mechanical analysis (DMA).

[0035] In this specification, "before heat curing" refers to a state in which the thermosetting adhesive sheet has not been subjected to a curing treatment or has been partially cured so that the reactivity is less than 50%. Specifically, the reactivity of a thermosetting resin sheet is measured using a differential scanning calorimeter (DSC) to measure the amount of heat generated [J / g] when the target adhesive sheet (target) and the target heated at a temperature at which the target can be heat-cured (heated target) are heated from 0°C to 300°C at a heating rate of 10°C / min. The amount of heat generated from the target from 0°C to 300°C is defined as the "amount of heat generated from the target," and the amount of heat generated from the heated target from 0°C to 300°C is defined as the "amount of heat generated after heating." Reactivity = Amount of heat generated after heating [J / g] ÷ Amount of heat generated from the target [J / g] × 100

[0036] The thermosetting adhesive sheet has the property of being cured by heat, and therefore preferably contains a thermosetting resin.

[0037] The thermosetting resin is a resin having a thermosetting functional group. Examples of the thermosetting resin include epoxy resin, phenol resin, amino resin, unsaturated polyester resin, polyurethane resin, silicone resin, thermosetting polyimide resin, melamine resin, and alkyd resin. The thermosetting resin may be used alone or in combination of two or more.

[0038] Examples of the epoxy resin include bisphenol-type epoxy resins, hydrogenated bisphenol-type epoxy resins, spirocyclic epoxy resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins, fluorene-type epoxy resins, terpene-type epoxy resins, glycidyl ether-type epoxy resins, glycidylamine-type epoxy resins, novolac-type epoxy resins, trishydroxyphenylmethane-type epoxy resins, tetraphenylolethane-type epoxy resins, hydantoin-type epoxy resins, and trisglycidyl isocyanurate-type epoxy resins. The epoxy resin may also be a modified epoxy resin such as a dimer acid-modified epoxy resin, a urethane-modified epoxy resin, or a rubber-modified epoxy resin. The epoxy resin may be an aliphatic epoxy resin, an alicyclic epoxy resin, or an aromatic epoxy resin, with alicyclic epoxy resins and aliphatic epoxy resins being preferred.

[0039] Examples of the bisphenol-type epoxy resins include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, brominated bisphenol A-type epoxy resins, and bisphenol AF-type epoxy resins. Examples of the glycidyl ether-type epoxy resins include tris(glycidyloxyphenyl)methane and tetrakis(glycidyloxyphenyl)ethane. Examples of the glycidylamine-type epoxy resins include tetraglycidyldiaminodiphenylmethane. Examples of the novolac-type epoxy resins include cresol novolac-type epoxy resins, phenol novolac-type epoxy resins, α-naphthol novolac-type epoxy resins, brominated phenol novolac-type epoxy resins, and orthocresol novolac-type epoxy resins. Among these, from the viewpoint of excellent handleability, bisphenol-type epoxy resins, novolac-type epoxy resins, and dimer acid-modified epoxy resins are preferred as the epoxy resins, with bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, novolac-type epoxy resins, and dimer acid-modified epoxy resins being more preferred. The bisphenol epoxy resin may have a block structure of a flexible component between the bisphenol skeletons, such as a linear hydrocarbon group or an alkylene glycol group, such as an ethylene glycol group, a propylene glycol group, or a butylene glycol group.

[0040] Among the thermosetting resins, epoxy resins are preferred. The epoxy resin preferably contains an epoxy resin with an epoxy equivalent of 200 to 800 g / eq, and more preferably a rubber-modified epoxy resin. In this specification, the epoxy resin with an epoxy equivalent of 200 to 800 g / eq may be referred to as "epoxy resin (a)," and the rubber-modified epoxy resin may be referred to as "rubber-modified epoxy resin (b)." The inclusion of epoxy resin (a) provides an appropriate distance between crosslinking points in the epoxy resin (a), making it easier to achieve the elastic modulus G' at 20°C of the thermosetting adhesive sheet within the above-mentioned range. Furthermore, the inclusion of rubber-modified epoxy resin (b) together with epoxy resin (a) toughens the thermosetting adhesive sheet containing epoxy resin (a), allowing it to maintain its shape more stably. The epoxy resin (a) and the rubber-modified epoxy resin (b) may each be used singly or in combination of two or more.

[0041] The epoxy resin (a) and the rubber-modified epoxy resin (b) are different resins. For example, the epoxy resin (a) may be an epoxy resin other than the rubber-modified epoxy resin, and the epoxy equivalent of the rubber-modified epoxy resin (b) may be less than 200 g / eq or more than 800 g / eq.

[0042] (Epoxy Resin (a)) The epoxy equivalent of the epoxy resin (a) is 200 to 800 g / eq. The epoxy equivalent is preferably 200 to 500 g / eq, more preferably 200 to 400 g / eq. The epoxy equivalent may also be 400 to 750 g / eq or 500 to 700 g / eq. When the epoxy equivalent is 200 g / eq or more, the thermosetting adhesive sheet has appropriate hardness, is less likely to separate when the release liner is peeled off, and is less likely to cause adhesive extrusion. When the epoxy equivalent is 800 g / eq or less, the thermosetting adhesive sheet has appropriate softness, has excellent adhesion to the adherend when one adhesive surface of the thermosetting adhesive sheet is attached to the adherend, and is excellent in transferability when the release liner attached to the other adhesive surface is peeled off.

[0043] The epoxy resin (a) may be a solid epoxy resin at room temperature, a liquid epoxy resin at room temperature, or a semi-solid epoxy resin at room temperature. However, from the viewpoint of easily obtaining a thermosetting adhesive sheet that has excellent transferability and is less likely to extrude, a semi-solid epoxy resin is preferred. Note that "semi-solid" refers to being solid at 20°C and liquid at 40°C. Furthermore, from the viewpoint of easily obtaining a thermosetting adhesive sheet that has excellent transferability and is less likely to extrude, the epoxy resin (a) preferably has a softening point of 70°C or less. Furthermore, the epoxy resin (a) is preferably a semi-solid or an epoxy resin with a softening point of 70°C or less.

[0044] As the epoxy resin (a), from the viewpoints of excellent handleability and ease of availability, bisphenol-type epoxy resins, novolac-type epoxy resins, and dimer acid-modified epoxy resins are preferred, and bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, novolac-type epoxy resins, and dimer acid-modified epoxy resins are more preferred.

[0045] (Rubber-Modified Epoxy Resin (b)) The rubber-modified epoxy resin (b) contains a rubber component in an epoxy resin. Examples of the rubber component include butadiene rubber, acrylic rubber, silicone rubber, butyl rubber, isoprene rubber, styrene rubber, chloroprene rubber, NBR, SBR, IR, EPR, terminal carboxy-modified butadiene-acrylonitrile copolymer rubber (CTBN), and styrene-butadiene elastomers. One type of rubber component may be used alone, or two or more types may be used. Of the rubber-modified epoxy resins (b), CTBN-modified epoxy resins are preferred from the viewpoint of being able to more sufficiently toughen the thermosetting adhesive sheet.

[0046] Examples of the epoxy resin in the rubber-modified epoxy resin (b) include those mentioned above. Among them, bisphenol-type epoxy resins are preferred, and bisphenol A-type epoxy resins are more preferred.

[0047] The epoxy equivalent of the rubber-modified epoxy resin (b) is preferably 1000 to 2000 g / eq, and more preferably 1200 to 1800 g / eq. When the epoxy equivalent is within this range, the elastic modulus G' at 20°C of the thermosetting adhesive sheet is likely to be within this range. Furthermore, when the epoxy equivalent is 1000 g / eq or more, the thermosetting adhesive sheet has appropriate hardness, which makes it less likely for the release liner to separate and for the adhesive to squeeze out.

[0048] Commercially available rubber-modified epoxy resins (b) can be used. Commercially available CTBN-modified bisphenol A epoxy resins include those under the trade names "HyPoxRK84L", "HyPoxRK820", "HyPoxRA1340", "HyPoxRA16213", "HyPoxRA840", and "HyPoxRA95" (all manufactured by HUNTSMAN), and "EPR-1630" (manufactured by ADEKA Corporation). Commercially available CTBN-modified bisphenol F epoxy resins include those under the trade names "HyPoxRF1320", "HyPoxRF1341", "HyPoxRF928", and "HyPoxRF933" (all manufactured by HUNTSMAN). Commercially available CTBN-modified glycol-type epoxy resins include those sold under the trade names "HyPox RM20" and "HyPox RM22" (both manufactured by HUNTSMAN). Other commercially available rubber-modified epoxy resins (b) include those sold under the trade names "TSR-960" (manufactured by DIC Corporation), "EPR-1415-1", "EPR-2000", and "EPR-2007" (all manufactured by ADEKA Corporation, NBR-modified epoxy resins).

[0049] The mass ratio of the epoxy resin (a) to the rubber-modified epoxy resin (b) [former:latter] is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40. When the proportion of the epoxy resin (a) is 20 or more, the transferability of the thermosetting adhesive sheet is superior. When the proportion of the rubber-modified epoxy resin (b) is 20 or more, the releasability when peeling one of the release liners from the thermosetting adhesive sheet is superior.

[0050] The content of the thermosetting resin (particularly the epoxy resin) in the thermosetting adhesive sheet is preferably 60% by mass or more, more preferably 70% by mass or more, based on the total amount (100% by mass) of the thermosetting adhesive sheet. The content is preferably 95% by mass or less, more preferably 90% by mass or less. The total content of the epoxy resin (a) and the rubber-modified epoxy resin (b) is preferably within the above range.

[0051] (Epoxy Curing Agent) When the thermosetting adhesive sheet contains an epoxy resin (particularly, epoxy resin (a) and rubber-modified epoxy resin (b)) as the thermosetting resin, the thermosetting adhesive sheet preferably contains an epoxy curing agent. The epoxy curing agent promotes polymerization of epoxy groups in the epoxy resin when heated. The epoxy curing agent may be used alone or in combination of two or more types.

[0052] As the epoxy curing agent, known or conventional curing agents used for curing epoxy resins can be used, and examples thereof include urea-based compounds, amine-based compounds, acid anhydride-based compounds, amide-based compounds, hydrazide-based curing agents, imidazole-based curing agents, imidazoline-based compounds, triphenylphosphine-based compounds, thermal base generators, trihalogenborane-based compounds, carboxylic acid-based compounds, phenolic resin-based compounds, and polymercaptan-based curing agents.

[0053] Examples of urea compounds include 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), N'-phenyl-N,N-dimethylurea, 1,1'-(methyl-1,3-phenylene)bis(3,3'-dimethylurea), 3-(4-chlorophenyl)-1,1-dimethylurea, N'-[3-[[[(dimethylamino)carbonyl]amino]methyl]-3,5,5-trimethylcyclohexyl]-N,N'-dimethylurea, and 3,3'-[methylenebis-(1,3-phenylene)]bis(1,1-dimethylurea).

[0054] Examples of the amine compounds include ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, amine adducts thereof, metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

[0055] Examples of acid anhydride compounds include methyltetrahydrophthalic anhydride (4-methyltetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, etc.), methylhexahydrophthalic anhydride (4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, etc.), dodecenyl succinic anhydride, methylendomethylenetetrahydrophthalic anhydride, phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylcyclohexene dicarboxylic acid, and the like. carboxylic anhydride, pyromellitic anhydride, trimellitic anhydride, benzophenone tetracarboxylic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, 4-(4-methyl-3-pentenyl)tetrahydrophthalic anhydride, succinic anhydride, adipic anhydride, sebacic anhydride, dodecanedioic anhydride, methylcyclohexene tetracarboxylic anhydride, vinyl ether-maleic anhydride copolymer, alkylstyrene-maleic anhydride copolymer, and the like.

[0056] Examples of the amide compounds include dicyandiamide and polyamide.

[0057] Examples of the hydrazide compounds include dihydrazides such as adipic acid dihydrazide.

[0058] Examples of imidazole compounds include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like.

[0059] Examples of imidazoline compounds include methylimidazoline, 2-ethyl-4-methylimidazoline, ethylimidazoline, isopropylimidazoline, 2,4-dimethylimidazoline, phenylimidazoline, undecylimidazoline, heptadecylimidazoline, and 2-phenyl-4-methylimidazoline.

[0060] Examples of triphenylphosphine compounds include triphenylphosphine, tributylphosphine, tri(p-methylphenyl)phosphine, tri(nonylphenyl)phosphine, diphenyltolylphosphine, tetraphenylphosphonium bromide, methyltriphenylphosphonium, methyltriphenylphosphonium chloride, methoxymethyltriphenylphosphonium, and benzyltriphenylphosphonium chloride. Triphenylphosphine compounds also include compounds having both a triphenylphosphine structure and a triphenylborane structure. Examples of such compounds include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-triborate, benzyltriphenylphosphonium tetraphenylborate, and triphenylphosphinetriphenylborane.

[0061] Examples of the thermal base generator include 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) or a salt thereof, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) or a salt thereof.

[0062] Examples of trihalogen borane compounds include trichloroborane.

[0063] The epoxy curing agent is preferably a latent curing agent. Latent curing agents exert their curing action due to the heat generated during thermal curing, and therefore provide a thermosetting adhesive sheet in a state before thermal curing with excellent storage stability, adhesiveness, and transferability. The epoxy curing agent may also be a microcapsule-type curing agent.

[0064] Among the epoxy curing agents, amide-based compounds are preferred, and dicyandiamide is more preferred, from the viewpoint of increasing the adhesive strength of the thermosetting adhesive sheet after curing. Furthermore, the epoxy curing agent preferably contains a urea-based compound and / or an imidazole-based compound. Furthermore, it is particularly preferred to contain a urea-based compound and / or an imidazole-based compound in addition to the amide-based compound. The urea-based compound and the imidazole-based compound (particularly the urea-based compound) act as a curing accelerator when the epoxy resin reacts with the amide-based compound, and have the function of accelerating the reaction rate.

[0065] The content of the epoxy curing agent in the thermosetting adhesive sheet is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, even more preferably 4 to 16 parts by mass, and particularly preferably 4.5 to 15 parts by mass, per 100 parts by mass of the total epoxy resin (particularly, 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) combined). When the content is within the above range, the adhesive strength of the thermosetting adhesive sheet after curing is higher.

[0066] The content of the amide compound in the thermosetting adhesive sheet is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 10 parts by mass, per 100 parts by mass of the total epoxy resin (particularly, 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) combined). When the content is within the above range, the adhesive strength of the thermosetting adhesive sheet after curing is higher.

[0067] The content of the urea compound and / or imidazole compound in the thermosetting adhesive sheet is preferably 1 to 10 parts by mass, more preferably 1.5 to 8 parts by mass, and even more preferably 2 to 7 parts by mass, per 100 parts by mass of the total epoxy resin (particularly, per 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) combined). When the content is within the above range, the adhesive strength of the thermosetting adhesive sheet after curing is higher.

[0068] (Filler) The thermosetting adhesive sheet preferably contains a filler. The inclusion of a filler makes it easier to adjust the elastic modulus G' at 80°C of the thermosetting adhesive sheet to the above-mentioned range. Only one type of filler may be used, or two or more types may be used. Examples of fillers include inorganic fillers and organic fillers.

[0069] Examples of constituent materials for the inorganic filler include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, boron nitride, silica (crystalline silica, amorphous silica, etc.), etc. Furthermore, examples of constituent materials for the inorganic filler include simple metals such as aluminum, gold, silver, copper, nickel, etc., alloys, amorphous carbon black, graphite, etc.

[0070] Examples of the inorganic filler include the fillers of the above-mentioned constituent materials, as well as mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, dolomite, quartz, cristobalite, hollow ceramic beads, hollow glass beads, and glass beads.

[0071] Examples of materials constituting the organic filler include polymethyl methacrylate (PMMA), polyimide, polyamideimide, polyetheretherketone, polyetherimide, and polyesterimide.

[0072] The shape of the filler is not particularly limited, and may be various shapes such as spherical, flake (scale-like), dendritic, fibrous, and amorphous (polyhedral).

[0073] Of the above fillers, inorganic fillers are preferred, and silica fillers are more preferred.

[0074] The silica filler may be subjected to a surface treatment such as hydrophobic treatment. Examples of the treating agent used for the hydrophobic treatment include organic silyl compounds such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, hexamethyldisilazane, methyltrialkoxysilane, dimethyldialkoxysilane, trimethylalkoxysilane, ethyltrichlorosilane, propyltrichlorosilane, hexyltrichlorosilane, long-chain alkyltrichlorosilane, ethyltrialkoxysilane, propyltrialkoxysilane, hexyltrialkoxysilane, long-chain alkyltrialkoxysilane, methacrylsilane, fluoroalkylsilane, and perfluoroalkylsilane; and silicone compounds such as dimethylpolysiloxane (silicone oil), methylphenylpolysiloxane, methylhydrogenpolysiloxane, and amino-modified silicone.

[0075] The average particle diameter of the filler is preferably 50 nm or less, more preferably 40 nm or less. When the average particle diameter is 50 nm or less, the adhesive is less likely to extrude. The average particle diameter of the filler is preferably 7 nm or more, more preferably 10 nm or more. When the average particle diameter is 7 nm or more, the bulk density is high and handling is excellent. The average particle diameter of the inorganic filler can be determined, for example, using a photometric particle size distribution meter (for example, product name "LA-910", manufactured by Horiba, Ltd.).

[0076] The specific surface area of ​​the filler is 30 m 2 / g or more is preferable, and 100m 2 / g or more. 2 When the specific surface area of ​​the filler is 500 m / g or more, the adhesive is less likely to extrude. 2 / g or less, and more preferably 350m 2 / g or less.

[0077] The specific surface area of ​​the filler per 100 g of the thermosetting adhesive sheet is 600 to 6000 m 2is preferable, and more preferably 800 to 5000 m 2 The specific surface area is 600 m 2 When the specific surface area is 6000 m or more, the adhesive is less likely to protrude. 2 When the thickness is equal to or less than this, the adhesive layer has excellent conformability to the irregularities of the adherend and excellent shear adhesive strength.

[0078] The content of the filler in the thermosetting adhesive sheet is preferably 5 to 40 parts by mass, more preferably 6 to 35 parts by mass, and even more preferably 8 to 30 parts by mass, per 100 parts by mass of the total amount of epoxy resin (particularly, 100 parts by mass of the total of epoxy resin (a) and rubber-modified epoxy resin (b)). When the content is 5 parts by mass or more, the elastic modulus G' at 80°C of the thermosetting adhesive sheet can be increased, and adhesive extrusion can be further suppressed. When the content is 40 parts by mass or less, the transferability of the thermosetting adhesive sheet is superior.

[0079] The thermosetting adhesive sheet may contain a colorant. The colorant may be a pigment or a dye. Examples of colorants include black colorants, cyan colorants, magenta colorants, and yellow colorants. The thermosetting adhesive sheet may contain only one type of colorant, or two or more types. The content of the colorant in the thermosetting adhesive sheet is preferably 0.05 to 5% by mass, and more preferably 0.1 to 2% by mass, relative to the total amount (100% by mass) of the thermosetting adhesive sheet.

[0080] Examples of black colorants include carbon black, carbon nanotubes, graphite, copper oxide, manganese dioxide, azo pigments such as azomethine azo black, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, complex oxide black pigments, anthraquinone organic black dyes, and azo organic black dyes. Examples of carbon black include furnace black, channel black, acetylene black, thermal black, and lamp black. Examples of black colorants include C.I. Solvent Black 3, 7, 22, 27, 29, 34, 43, and 70; C.I. Direct Black 17, 19, 22, 32, 38, 51, and 71; C.I. Acid Black 1, 2, 24, 26, 31, 48, 52, 107, 109, 110, 119, 154; C.I. Disperse Black 1, 3, 10, 24; C.I. Pigment Black 1, 7, and the like.

[0081] Examples of cyan colorants include C.I. Solvent Blue 25, 36, 60, 70, 93, and 95; C.I. Acid Blue 6 and 45; C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 16, 17, 17:1, 18, 22, 25, 56, 60, 63, 65, and 66; C.I. Bat Blue 4; 60, and C.I. Pigment Green 7.

[0082] Examples of magenta colorants include C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63, 81, 82, 83, 84, 100, 109, 111, 121, and 122; C.I. Disperse Red 9; C.I. Solvent Violet 8, 13, 14, 21, and 27; C.I. Disperse Violet 1; C.I. C.I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; C.I. Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28, etc. Examples of magenta colorants include, for example, C.I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 42, 48:1, 48:2, 48:3, 48:4, 49, 49:1, 50, 51, 52, 52:2, 53:1, 54, 55, 56, 57:1, 58, 60, 60:1, 63, 63:1, 63:2, 64, 64:1, 6 C.I.7, 68, 81, 83, 87, 88, 89, 90, 92, 101, 104, 105, 106, 108, 112, 114, 122, 123, 139, 144, 146, 147, 149, 150, 151, 163, 166, 168, 170, 171, 172, 175, 176, 177, 178, 179, 184, 185, 187, 190, 193, 202, 206, 207, 209, 219, 222, 224, 238, 245; C.I. Pigment Violet 3, 9, 19, 23, 31, 32, 33, 36, 38, 43, and 50; C.I. Bat Red 1, 2, 10, 13, 15, 23, 29, and 35.

[0083] Examples of yellow colorants include C.I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162; C.I. Pigment Orange 31 and 43; C.I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, and 100, C.I. Bat Yellow 1, 3, 20, and the like.

[0084] The thermosetting adhesive sheet may contain other components in addition to the various components described above, provided that the effects of the present invention are not impaired. Examples of such other components include other curing accelerators, thermoplastic resins, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), antioxidants, antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, UV absorbers, polymerization inhibitors, flame retardants, silane coupling agents, ion trapping agents, and foil-like materials. Only one of the above other components may be used, or two or more may be used.

[0085] The thickness of the thermosetting adhesive sheet is not particularly limited, but is preferably 10 to 1000 μm, more preferably 30 to 750 μm, and even more preferably 50 to 500 μm. When the thickness is 10 μm or more, the thermosetting adhesive sheet has better adhesiveness when used to bond members together.

[0086] The thermosetting adhesive sheet is sandwiched between two sheets of AL alloy A5052 whose adhesive portions have been polished with 100-grain sandpaper, and the two adhesive surfaces are bonded together and thermally cured. The shear adhesive strength, measured at a tensile speed of 1.3 mm / min and a peel angle of 0°, is preferably 1 MPa or more, more preferably 5 MPa or more, and even more preferably 10 MPa or more. A shear adhesive strength of 1 MPa or more provides excellent adhesion between members.

[0087] The thermosetting adhesive sheet of the present invention is preferably used for bonding components together. Because the thermosetting adhesive sheet has excellent adhesion to metals, it is preferably used for bonding metal components together. It is also preferably used for bonding metal components together. The thermosetting resin sheet of the present invention also has excellent adhesion between components made of different materials. Therefore, the thermosetting adhesive sheet of the present invention is also preferably used for bonding metal components and fiber-reinforced resin components. Examples of the reinforcing fibers include known or commonly used reinforcing fibers, such as carbon fiber, glass fiber, aramid fiber, boron fiber, graphite fiber, silicon carbide fiber, high-strength polyethylene fiber, tungsten carbide fiber, and polyparaphenylenebenzoxazole fiber (PBO fiber).

[0088] The thermosetting adhesive sheet may have a release liner (separator) attached to the surface (adhesive surface) of the adhesive sheet until use. Each adhesive surface on both sides of the thermosetting adhesive sheet may be protected by two release liners, or may be protected by a single release liner with release surfaces on both sides in a rolled form (rolled body). The release liner is used as a protective material for the adhesive sheet and is peeled off when the sheet is attached to the adherend. The release liner is not necessarily required.

[0089] The release liner can be a conventional release paper, and is not particularly limited. Examples include substrates with a release treatment layer, low-adhesion substrates made of fluoropolymers, and low-adhesion substrates made of non-polar polymers. Examples of substrates with a release treatment layer include plastic films and papers surface-treated with release agents such as silicone-based, long-chain alkyl-based, fluorine-based, and molybdenum sulfide-based release agents. Examples of fluorine-based polymers in the low-adhesion substrates made of fluoropolymers include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymers, and chlorofluoroethylene-vinylidene fluoride copolymers. Examples of non-polar polymers include olefin-based resins (e.g., polyethylene, polypropylene, etc.). The release liner can be formed by known or conventional methods. The thickness of the release liner is also not particularly limited.

[0090] The thermosetting adhesive sheet can be produced, for example, by applying an adhesive composition for forming an adhesive sheet onto a release liner and, if necessary, drying and solidifying the resulting adhesive composition layer. The adhesive composition can be produced, for example, by dissolving or dispersing the various components described above, such as the epoxy resin (a), the rubber-modified epoxy resin (b), the epoxy curing agent, and the filler, in a solvent such as an organic solvent and then mixing them.

[0091] The thermosetting adhesive sheet of the present invention exhibits excellent handling properties, allowing the release liner to be easily peeled from the adhesive surface when peeled off, and is less likely to cause adhesive extrusion. Therefore, for example, when peeling off one release liner from a thermosetting adhesive sheet whose adhesive surfaces are protected by release liners, the release liner can be peeled off without causing a "sad separation" or damaging the adhesive sheet interface. Furthermore, when one adhesive surface of the thermosetting double-sided adhesive sheet is bonded to a member and then the release liner bonded to the other adhesive surface is peeled off, the adhesive sheet exhibits excellent transferability, allowing the release liner to be easily peeled off from the adhesive surface of the adhesive sheet without peeling off the adhesive sheet and the release liner from the member to which it is bonded. Furthermore, after being bonded to an adherend, the thermosetting adhesive sheet of the present invention is heated to cure the adhesive sheet and firmly adhere to the member. When adherend members are bonded together via a thermosetting adhesive sheet, or when the thermosetting adhesive sheet is heated to harden, the adhesive in the adhesive sheet is less likely to squeeze out from between the members due to pressure or heat.

[0092] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples in any way. The compositions of the components constituting the adhesive sheets in the examples and comparative examples are shown in the tables. However, in the tables, the units of the numerical values ​​representing the composition of the adhesive sheet are relative "parts by mass" within the adhesive sheet.

[0093] Example 1: To a rubber-modified epoxy resin (trade name "HyPoxRK84L" manufactured by HUNTSMAN), methyl ethyl ketone (MEK) was added to a solids content of 50 wt%, and the mixture was thoroughly stirred to obtain a rubber-modified epoxy resin solution. 80 parts by mass of the rubber-modified epoxy resin solution (40 parts by mass as rubber-modified epoxy resin), 60 parts by mass of bisphenol A epoxy resin (trade name "jER-834" manufactured by Mitsubishi Chemical Corporation), 5 parts by mass of silica filler (trade name "Aerosil RY-200" manufactured by Nippon Aerosil Co., Ltd.), 5 parts by mass of a dicyandiamide curing agent (trade name "Omicure DDA-50" manufactured by HUNTSMAN), and 2 parts by mass of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed, and MEK was added to a solids content of 45 wt%. The mixture was then stirred at 2000 rpm for 1 minute using a high-speed mixer (trade name "Homo Disper", manufactured by Primix Corporation), and further degassed at 2000 rpm for 1 minute using a planetary mixer (trade name "Awatori Rentaro", manufactured by Thinky Corporation) to prepare an adhesive composition.

[0094] Next, the adhesive composition was applied using an applicator to the release-treated surface of a 75 μm thick PET separator (two-sided separator) having a release-treated surface, so that the thickness when dried was 0.1 mm, to form an adhesive composition layer. The adhesive composition was then heated at 60°C for 10 minutes to dry off the solvent, forming an adhesive layer. The release-treated surface of a 38 μm thick PET separator (single-sided separator) having a release-treated surface was then bonded to the surface of the adhesive layer, to produce an adhesive sheet.

[0095] Examples 2 to 18 and Comparative Examples 1 to 6 Adhesive sheets were prepared in the same manner as in Example 1, except that the types and blending amounts of the various raw materials used in preparing the adhesive compositions were changed as shown in Tables 1 and 2.

[0096] The various raw materials shown in Tables 1 and 2 are as follows. (Epoxy resin (a)) jER-828: trade name "jER-828", bisphenol A type epoxy resin that is liquid at room temperature, epoxy equivalent weight 184 to 194 g / eq, manufactured by Mitsubishi Chemical Corporation jER-834: trade name "jER-834", semi-solid bisphenol A type epoxy resin, epoxy equivalent weight 230 to 270 g / eq, manufactured by Mitsubishi Chemical Corporation jER-1001: trade name "jER-1001", solid bisphenol A type epoxy resin, epoxy equivalent weight 450 to 500 g / eq, manufactured by Mitsubishi Chemical Corporation jER-872: trade name "jER-872", semi-solid dimer acid-modified epoxy resin, epoxy equivalent weight 600 to 700 g / eq, manufactured by Mitsubishi Chemical Corporation jER-157S65B80: Trade name "jER-157S65B80", solution type solid special novolac epoxy resin, epoxy equivalent 200 to 220 g / eq, manufactured by Mitsubishi Chemical Corporation jER-YX7105: Trade name "jER-YX7105", ultra-flexible epoxy resin that is liquid at room temperature, epoxy equivalent 440 to 520 g / eq, manufactured by Mitsubishi Chemical Corporation (rubber-modified epoxy resin (b)) EPR-1630: Trade name "EPR-1630", epoxy resin obtained by reacting epoxy and CTBN, epoxy equivalent 900 g / eq, manufactured by ADEKA Corporation HyPoxRK84L: trade name "HyPoxRK84L", epoxy resin obtained by reacting bisphenol A type epoxy with CTBN, epoxy equivalent 1250 to 1500 g / eq, manufactured by HUNTSMAN (epoxy curing agent) Omicure DDA-50: trade name "Omicure DDA-50", dicyandiamide, manufactured by HUNTSMAN DCMU: 3-(3,4-dichlorophenyl)-1,1-dimethylurea, manufactured by Tokyo Chemical Industry Co., Ltd. Omicure U-24M: trade name "Omicure U-24M", 1,1'-(4-methyl-1,3-phenylene)bis(3,3'-dimethylurea), manufactured by HUNTSMAN 2PHZ-PW: Trade name "2PHZ-PW", 2-phenyl-4,5-dihydroxymethylimidazole, manufactured by Shikoku Chemical Industry Co., Ltd. (filler) Aerosil RY-50: Trade name "Aerosil RY-50", hydrophobized fumed silica, specific surface area 35 to 65 m 2 / g, average particle size 40 nm, Aerosil RY-200 manufactured by Nippon Aerosil Co., Ltd.: trade name "Aerosil RY-200", hydrophobized fumed silica, specific surface area 175 to 225 m 2 / g, average particle size 12 nm, manufactured by Nippon Aerosil Co., Ltd.

[0097] <Evaluation> The adhesive sheets obtained in the Examples and Comparative Examples were evaluated as follows, and the results are shown in the table.

[0098] (1) Elastic Modulus G' The adhesive layers of the adhesive sheets prepared in the Examples and Comparative Examples were laminated to a thickness of 1 mm or more and cut to a diameter of 8 mm. Using a rheometer (product name "ARES G2", manufactured by TA Instruments), dynamic viscoelasticity was measured at a frequency of 1 Hz, a heating rate of 5°C / min, and a measurement temperature of 0 to 100°C. If the elastic modulus G' during measurement was 1 MPa or less, the measurement was discontinued even if the temperature was below 100°C. Furthermore, if the temperature at which the elastic modulus G' became 1 MPa or less was 80°C or less, the elastic modulus G' at 80°C was recorded as 1 MPa or less. In this manner, the elastic modulus G' at 20°C and 80°C was measured.

[0099] (2) Separation The adhesive sheets prepared in the Examples and Comparative Examples were cut into a piece 10 mm wide x 50 mm long. The separators were peeled from the edge at a rate of 10 mm / min, and evaluation was performed with "Good" if the adhesive remained on only one separator, and "Poor" if the adhesive remained on both separators.

[0100] (3) Transferability The adhesive sheets prepared in the Examples and Comparative Examples were cut into a width of 10 mm and a length of 50 mm. SUS304BA stainless steel washed with ethyl acetate was used as the adherend. The separator on one side of the cut adhesive sheet was peeled off, and the adhesive surface was attached to the adherend. After leaving the sheet at room temperature for 5 minutes, the adhesive was evaluated as "Good" if it remained on the adherend when the separator on the second side was peeled off, and as "Poor" if it remained on the separator on the second side or on both the adherend and the separator on the second side.

[0101] (4) Adhesive Protrusion The test pieces prepared in the above shear adhesive strength measurement were observed to check the amount of adhesive protruding from between the two adherends. Protruding adhesive of less than 1 mm was evaluated as "Good", adhesive of 1 mm or more but less than 2 mm was evaluated as "Good", adhesive of 2 mm or more was evaluated as "Poor".

[0102] (5) Shear Adhesion Strength The basic procedure was performed in accordance with JIS K6850:1999. Specifically, a 25 mm wide x 100 mm long x 1.6 mm thick Al alloy A5052 was first polished three times with 100 grit sandpaper at 45° and 135° angles along the length. The polished surface was washed with ethyl acetate and air-dried for 30 minutes to obtain an adherend. Separately, the adhesive sheets prepared in the Examples and Comparative Examples were cut into 25 mm wide x 12.5 mm long pieces. The separator on one side of the cut adhesive sheet was peeled off, and the adhesive surface was attached to an adherend. Next, the separator on the second side was peeled off and attached to another adherend. If the adhesive sheet did not transfer when the separator on the second side was peeled off, the sheet was laminated at 60°C for 10 seconds to transfer the adhesive. The two adherends were temporarily fixed at approximately 2-7 kPa. The adhesive sheet was cured by heating in a 150°C oven for 1 hour in the temporarily fixed state, and then cooled and released to prepare a test specimen. 25 mm of each end of the test specimen was fixed in the chuck of a tensile tester, and the tester was moved at a speed of 1.3 mm / min until the specimen broke. The maximum stress was taken as the shear adhesive strength.

[0103]

[0104]

[0105] As shown in Tables 1 and 2, the thermosetting adhesive sheets of the present invention were evaluated as having no peeling, excellent transferability, and excellent handleability. Furthermore, no adhesive extrusion occurred. On the other hand, when the elastic modulus G' at 80°C was low (Comparative Examples 1 and 2), adhesive extrusion was observed. When the elastic modulus G' at 20°C was high (Comparative Example 3), the sheets were evaluated as having poor transferability and poor handleability. When the elastic modulus G' at 20°C was low (Comparative Examples 2, 4 to 6), peeling occurred, and the sheets were evaluated as having poor handleability.

[0106] 1 Thermosetting adhesive sheet 2, 3 Release liner

Claims

1. A thermosetting adhesive sheet having an elastic modulus G' at 20°C of 150 to 3000 kPa and an elastic modulus G' at 80°C of 1 kPa or more.

2. 2. The thermosetting adhesive sheet according to claim 1, comprising an epoxy resin (a) having an epoxy equivalent of 200 to 800 g / eq and a rubber-modified epoxy resin (b).

3. 3. The thermosetting adhesive sheet according to claim 2, wherein the epoxy resin (a) is at least one selected from the group consisting of bisphenol-type epoxy resins, novolac-type epoxy resins, and dimer acid-modified epoxy resins.

4. 4. The thermosetting adhesive sheet according to claim 2, wherein the mass ratio of the epoxy resin (a) to the rubber-modified epoxy resin (b) is 20:80 to 80:

20.

5. 4. The thermosetting adhesive sheet according to claim 2, further comprising 0.5 to 30 parts by mass of an epoxy curing agent per 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) combined.

6. The thermosetting adhesive sheet according to claim 5, wherein the epoxy curing agent contains dicyandiamide, and the content of the dicyandiamide is 0.5 to 20 parts by mass per 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) combined.

7. The thermosetting adhesive sheet according to claim 5, wherein the epoxy curing agent contains a urea-based compound and / or an imidazole-based compound, and the content of the urea-based compound and / or the imidazole-based compound is 1 to 10 parts by mass per 100 parts by mass of the epoxy resin (a) and the rubber-modified epoxy resin (b) in total.

8. The thermosetting adhesive sheet according to any one of claims 1 to 3, further comprising a filler.

9. The thermosetting adhesive sheet according to claim 8, wherein the average particle size of the filler is 7 to 50 nm.

10. The specific surface area of ​​the filler per 100 g of the thermosetting adhesive sheet is 600 to 6000 m ２ The thermosetting adhesive sheet according to claim 8 ,

11. The thermosetting adhesive sheet according to any one of claims 1 to 3, which is used for bonding members, at least one of which is made of a metal.

12. The thermosetting adhesive sheet according to claim 11, which is used for bonding between metal members or between a metal member and a fiber-reinforced resin member.