Easily dismantled adhesive material, article and dismantling method

Abstract

To provide an easily disassemblable adhesive material which has both excellent adhesive strength and easy disassemblability.SOLUTION: An easily disassemblable adhesive material contains a thermosetting resin and thermoexpansible particles. The thermosetting resin contains an epoxy resin, and a curing component containing either or both of a curing agent and a curing accelerator. The thermosetting resin contains a thermally dissociable compound having a thermally dissociable structure in any one form of the following (i) and (ii). (i) When the curing component contains the curing agent, either or both of the epoxy resin and the curing agent contain the thermally dissociable compound. (ii) When the curing component does not contain the curing agent, the epoxy resin contains the thermally dissociable compound.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an easily dismantlable adhesion technique. [Background technology]

[0002] An easily dismantlable adhesive material is an adhesive material that has sufficient adhesive strength according to the intended use, and also has the property of being able to reduce the adhesive strength at any time and easily peel off (dismantle). Demand for such materials is increasing for applications such as the separate collection of different materials, the repair and replacement of defective parts, and the improvement of productivity through temporary adhesion in the manufacturing process. To design an easily dismantlable adhesive material, it is necessary to reduce the adhesive strength once it has been developed. Also, unlike aging deterioration, easily dismantlable adhesive materials are required to be dismantled on demand and in a short time. Therefore, it is necessary to incorporate a mechanism for dismantling that causes a decrease in adhesive strength due to decomposition, a decrease in interfacial interaction, or a change in elastic modulus in response to an external stimuli.

[0003] As prior art relating to easily dismantlable adhesive materials, for example, Patent Documents 1 to 4 can be mentioned.

[0004] Patent Document 1 describes a dismantlable adhesive composition containing (A) an organic adhesive component such as an epoxy resin adhesive, and (B) a compound of inorganic onium ions and halogen ions. Patent Document 1 describes that when an external stimulus is applied to an adhesive structure bonded using this dismantlable adhesive composition, the compound of inorganic onium ions and halogen ions promotes thermal decomposition of the adhesive, greatly reducing or eliminating the adhesive strength. It also describes that chemical foaming agents such as thermally expandable graphite, thermally expandable resin balloons, and azodicarbonamide can be used in combination to improve dismantlability.

[0005] Patent Document 2 describes an adhesive composition that contains a reactive adhesive component and a thermally decomposable organic compound having a functional group that reacts with the reactive adhesive component and a thermally decomposable group. In this adhesive composition, the thermally decomposable organic compound has an azo group, a hydrazo group (-NH-NH-), a hydrazino group (-NHNH 2 ) and peroxide groups.

[0006] Patent Document 3 discloses a method for producing a hydrazine and / or a carboxylic acid dihydrazide and an intramolecular carboxylic acid anhydride by the reaction of -NH 2 Patent Document 3 describes an epoxy resin curing agent made of a polycarboxylic acid containing a diacylhydrazine structure, in which a carboxylic anhydride group is reacted with an acylhydrazine group in an equimolar ratio to a diacylhydrazine group. According to Patent Document 3, (i) this epoxy resin curing agent is a polycarboxylic acid having a structure in the molecule that can be easily decomposed by an oxidizing agent, so that by using it as an epoxy resin curing agent, an easily dismantled epoxy resin composition having oxidative decomposition properties can be obtained.

[0007] Patent Document 4 describes an easily dismantled adhesive that uses an epoxy resin (containing an ether bond moiety) represented by a specific general formula. According to the description in Patent Document 4, when the bonded body (cured product) of this easily dismantled adhesive is irradiated with energy, melting and decomposition proceeds from the ether bond moiety of the epoxy resin, and the bonded substrate can be easily dismantled (peeled off) from the bonded body. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2015-196793 A [Patent Document 2] JP 2013-256557 A [Patent Document 3] JP 2012-007036 A [Patent Document 4] JP 2006-111716 A Summary of the Invention [Problem to be solved by the invention]

[0009] The key point in designing an easily dismantlable adhesive material is how to achieve both high adhesive strength and long-term stability during use, and the ability to easily peel off with a small amount of force. In other words, the key points in design are that the mechanism for dismantling does not impede adhesiveness, and that the adhesive strength decreases at any time. It is often not easy to achieve both of these contradictory properties.

[0010] In view of the above, an object of the present invention is to provide an easily dismantlable adhesive material that combines excellent adhesive strength with easy dismantling properties. [Means for solving the problem]

[0011] The present invention, which solves the above-mentioned problems, is as follows.

[0012] The easily dismantlable adhesive material of the present invention is The thermosetting resin and the thermally expandable particles are included, Thermosetting resins are Epoxy resin, a curing component including one or both of a curing agent and a curing accelerator; Including, The thermosetting resin contains a thermally dissociable compound having a thermally dissociable structure in either of the following embodiments (i) or (ii). (i) When the curing component contains a curing agent, one or both of the epoxy resin and the curing agent contain a thermally dissociable compound. (ii) When the curing component does not include a curing agent, the epoxy resin includes a thermally dissociable compound.

[0013] The article of the present invention also comprises: The adhesive comprises an adherend and a cured product of the above-mentioned easily dismantlable adhesive material bonded to the adherend.

[0014] The dismantling method of the present invention further comprises: The method includes a dismantling step of heating the article to dismantle the adherend and the cured body of the easily dismantlable adhesive material. Effect of the Invention

[0015] The easily dismantlable adhesive material of the present invention significantly improves the trade-off balance between excellent practical strength and easy dismantling due to the synergistic effect of the thermal dissociation action of the thermally dissociable structure and the expansion action of the thermally expandable particles. According to the present invention, it is possible to achieve both high adhesive strength during use and easy dismantling ability that allows easy peeling with weak force. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram for explaining a conventional technique; [Diagram 2] FIG. 1 is a diagram for explaining the dismantling mechanism of an easily dismantlable adhesive material. [Diagram 3] FIG. 2 is a schematic diagram showing the microstructure in a hardened body of an easily dismantlable adhesive material. [Figure 4] FIG. 2 is a diagram for explaining the disintegration mechanism when the thermally dissociable structure is a structure formed by a Diels-Alder reaction (Diels-Alder adduct structure). [Diagram 5] FIG. 1 is a diagram showing an example in which a compound having a Diels-Alder adduct structure is used as a thermally dissociable compound. [Figure 6] FIG. 1 is a diagram for explaining thermal dissociation of a Diels-Alder adduct structure. [Figure 7] FIG. 1 is a diagram for explaining a thermally expandable microcapsule. [Figure 8] This is the 1H NMR spectrum of furfuryl glycidyl ether (FGE). [Figure 9] This is the 1H NMR spectrum of 2,2'-(methylenebis(4,1-phenylene))bis(4-((oxiran-2-ylmethoxy)methyl)-3a,4,7,7a-tetrahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione) (FDB). [Figure 10]1 is an SS curve obtained in a tensile shear test in Example 1. [Figure 11] 1 is an SS curve obtained in a tensile shear test in Comparative Example 1. [Figure 12] 1 is an SS curve obtained in a tensile shear test in Comparative Example 2. [Figure 13] 1 is a bar graph for comparing ease of dismantling in Example 1, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the description of groups (atomic groups) in this specification, when a description is made without specifying whether the group is substituted or unsubstituted, the description includes both groups having no substituents and groups having a substituent. For example, an "alkyl group" includes not only an alkyl group having no substituents (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, the term "organic group" means an atomic group obtained by removing one or more hydrogen atoms from an organic compound, unless otherwise specified. For example, a "monovalent organic group" refers to an atomic group obtained by removing one hydrogen atom from any organic compound. In this specification, the notation "to" in relation to a numerical range means greater than or equal to or less than. For example, the notation "100 to 200°C" means 100°C or higher and 200°C or lower.

[0018] [Easy to disassemble adhesive material] The easily dismantlable adhesive material of the present embodiment contains thermally expandable particles and a thermosetting resin containing a thermally dissociable compound having a thermally dissociable structure in its molecule. The easily dismantlable adhesive material of this embodiment improves the trade-off balance between excellent adhesive strength and easy dismantling due to the synergistic effect of the thermally expandable particles and the thermally dissociable compound.

[0019] Conventionally, an easily dismantlable adhesive material using thermally expandable particles has been known. As shown in FIG. 1, this is a method of promoting peeling by expanding the thermally expandable particles by heating and increasing the volume of the cured resin. However, in order to sufficiently expand the cured resin, a large amount of thermally expandable particles must be used, which tends to reduce the adhesive strength during adhesion. However, if the amount of thermally expandable particles is small, the cured resin cannot be sufficiently expanded, making it difficult to obtain sufficient ease of dismantling. In addition, particularly when the crosslink density of the cured resin is high, the expansion of the thermally expandable particles is inhibited by the dense three-dimensional network structure, making it difficult to obtain sufficient ease of dismantling.

[0020] On the other hand, the easily dismantlable adhesive material of the present embodiment can obtain excellent adhesive strength and ease of dismantling, which cannot be obtained solely by the mechanism of volume expansion of the resin cured body, due to the synergistic effect of the heat-expanding particles and the heat-dissociable compound. Specifically, when the easily dismantlable adhesive material of this embodiment is attached to an adherend and then a first heat treatment is performed, a cured body having a crosslinked structure is typically obtained. When a second heat treatment is then performed, the thermally expandable particles expand and the thermally dissociable structure of the thermally dissociable compound dissociates. The synergistic effect of the expansion of the thermally expandable particles and the dissociation of the thermally dissociable structure weakens the cured body itself sufficiently to enable easy peeling (Figure 2).

[0021] As described above, the easily dismantlable adhesive material utilizing the expansion action of the heat-expanding particles is known. In contrast, the easily dismantlable adhesive material of the present embodiment significantly improves the trade-off balance between excellent practical strength and easy dismantling due to the synergistic effect of the expansion action of the heat-expanding particles and the dissociation action of the heat-dissociable structure. By using the easily dismantlable adhesive material of the present embodiment, adhesive strength and long-term stability, as well as dismantlability that allows easy peeling with weak force, are realized.

[0022] A representative application of the dismantlable adhesive material of this embodiment includes applying the adhesive material to the surface of an adherend, performing a first heat treatment to obtain a hardened body that bonds to the adherend, and then performing a second heat treatment on the hardened body to dismantle the adherend and the hardened body.

[0023] The easily dismantlable adhesive material of the present embodiment may be a two-liquid adhesive material containing an epoxy resin and either or both of a curing agent and a curing accelerator, that is, the epoxy resin and either or both of the curing agent and the curing accelerator are filled in separate containers and mixed immediately before use. Of course, the easily dismantlable adhesive material of the present embodiment may be a one-liquid adhesive material containing these.

[0024] The components of the easily dismantlable adhesive material of this embodiment will be described below.

[0025] [Thermally dissociable compound] The thermally dissociable compound is a compound having a thermally dissociable structure in the molecule. The thermally dissociable structure refers to a structure containing a bond that dissociates when heated (hereinafter, appropriately referred to as "thermally dissociable bond"). The thermally dissociable compound may have only one thermally dissociable structure in the molecule, or may have two or more (e.g., 2 to 4) thermally dissociable structures in the molecule. By using a thermally dissociable compound having two or more thermally dissociable structures in the molecule, the ease of disassembly can be further improved. The thermally dissociable bond is preferably a covalent bond. By selecting an appropriate thermally dissociable structure, the generation of low molecular weight compounds during dissociation can be suppressed, leading to a reduction in the amount of volatile organic compounds (VOCs) generated, which is often a problem with easily dismantlable adhesive materials.

[0026] By including a thermally dissociable compound in a thermosetting resin, it is possible to provide a location in the cured body where dissociation occurs due to heat. Figure 3 is a schematic diagram of the microstructure in the cured body (thermally expandable particles are not shown). The thermally dissociable structure contained in the cured body dissociates when heated (Δ).

[0027] FIG. 4 is a diagram for explaining the dismantling mechanism when the thermally dissociable structure is a structure formed by a Diels-Alder reaction (hereinafter also referred to as a "Diels-Alder adduct structure"). Heating causes a retro-Diels-Alder reaction (r-DA reaction) to dissociate the covalent bond. Easy dismantling is achieved by the synergistic effect of this bond dissociation and the expansion of the thermally expandable particles. In other words, by providing a portion in the cured body where dissociation occurs due to heat, excellent easy dismantling can be achieved by the synergistic effect with the thermally expandable particles.

[0028] FIG. 5 shows an example in which a compound having a Diels-Alder adduct structure is used as the thermally dissociable compound. In this example, two types of epoxy resins are used, one of which has a Diels-Alder adduct structure. A cured product can be obtained by reacting these epoxy resins with a curing agent (in FIG. 5, diethylenetriamine is used as the curing agent, and it is heated at 60°C for 7 hours). The obtained cured product has a site where dissociation occurs due to heat. In this example, the two types of epoxy resins and the curing agent are considered to be distributed substantially uniformly in the cured product. It is considered that the synergistic effect of the heat-dissociable structure substantially uniformly distributed in the cured product and the thermally expandable particles weakens the entire cured product uniformly, resulting in good dismantling properties.

[0029] Incidentally, as a design policy other than uniform distribution, a design that promotes the destruction of the crosslinked structure near the interface of the cured body by introducing a thermally dissociable bond into a component that is likely to be unevenly distributed at the interface among the components in the easily dismantlable adhesive material is also conceivable. For example, a design that uses a thermally dissociable compound having a fluorine atom-containing group or a silicon atom-containing group to unevenly distribute the thermally dissociable compound at the interface of the cured body is conceivable.

[0030] FIG. 6 is a diagram for explaining the thermal dissociation of the Diels-Alder adduct structure. In FIG. 1 and R 2 each independently represents a chemical structure in the cured product. In the Diels-Alder adduct structure, for example, heat treatment at 80°C to 160°C, specifically at about 90°C to 150°C, causes a retro-Diels-Alder reaction and dissociates the covalent bond (the reaction proceeds from left to right in Figure 6). That is, the heat destroys some of the bonds that constitute the three-dimensional crosslinked structure in the cured body. This results in a decrease in the adhesive strength between the easily dismantlable adhesive material and the adherend.

[0031] The thermally dissociable structure can be one of two types: (i) An irreversible thermally dissociable structure that does not recombine even when cooled to room temperature (25°C) after being thermally dissociated. (ii) A reversible thermally dissociable structure that dissociates when heated and then reassembles when cooled to room temperature (25°C).

[0032] The thermally dissociable structure of this embodiment may be either of the above (i) or (ii). The Diels-Alder adduct structure generally corresponds to the above reversible type thermally dissociable structure (ii). When the thermally dissociable structure is the reversible type thermally dissociable structure (ii) above, even if the bond dissociation occurs due to the heat treatment (first heat treatment) when the easily dismantled adhesive material of this embodiment is thermally cured, re-bonding occurs at the stage of returning to room temperature thereafter. Therefore, the mechanical strength of the obtained cured body and the adhesive strength with the adherend can be made sufficient. On the other hand, in the heat treatment (second heat treatment) during disassembly, the heat-expanding particles expand, suppressing recombination. This is because the dissociated parts are "pulled apart" by the expansion of the heat-expanding particles. In other words, even if a reversible heat-dissociable structure is adopted as the heat-dissociable structure, the presence of the heat-expanding particles makes the reversible reaction "irreversible," and the hardened body is easily weakened sufficiently.

[0033] The preferred dissociation temperature T of the thermally dissociable structure DIS is as follows: In the case of the irreversible thermally dissociable structure of (i), the dissociation temperature T DISis preferably 90° C. or higher, more preferably 110° C. or higher. This allows a wide margin for the heat treatment conditions of the first heat treatment for obtaining a hardened body. DIS The upper limit of the temperature is preferably 260° C., and more preferably 200° C. By doing so, the energy required for dismantling can be reduced. In the case of the reversible type thermally dissociable structure (ii), even if dissociation occurs during the first heat treatment to obtain a cured body, recombination occurs when the temperature is returned to room temperature, so that the mechanical strength and adhesive strength to the adherend of the obtained cured body can be sufficient. DIS There is no problem even if the temperature is low, as long as it is higher than room temperature (for example, 30° C. or higher). Dissociation temperature T of the thermally dissociable structure in the case of a reversible type of thermally dissociable structure DIS is, for example, 40° C. or higher, preferably 80° C. or higher, more preferably 90° C. or higher, even more preferably 100° C. or higher, particularly preferably 110° C. or higher, and particularly preferably 115° C. or higher. DIS By setting the temperature at a relatively high level, the heat resistance of the hardened body before dismantling can be increased. In addition, the dissociation temperature T DIS is, for example, 260° C. or less, preferably 200° C. or less, more preferably 160° C. or less, and further preferably 150° C. or less. By doing so, it is possible to reduce the energy required for dismantling. From the viewpoint of prioritizing thermal stability before dismantling, T DIS It is preferable to select a thermally dissociable structure with a relatively large T. DIS It is preferable to select a thermally dissociable structure with a relatively small T. In other words, it is necessary to select an appropriate T taking into consideration the purpose and place of use of the easily dismantled adhesive material. DIS It is preferable to select a thermally dissociable structure having the following structure:

[0034] Dissociation temperature T of thermally dissociable structure DISRegarding the temperature, for example, the temperature at the peak position corresponding to the dissociation reaction when the thermally dissociable compound is subjected to differential scanning calorimetry at a heating rate of 10° C. / min can be used.

[0035] Specific examples of structures containing an irreversible thermally dissociable structure include a peroxide bond structure (-OO-), a tertiary ester structure (-CO-O-CRR'-, where R and R' are each independently an organic group such as an alkyl group), and a tertiary carbonate structure (-O-CO-O-CRR'-, where R and R' are each independently an organic group such as an alkyl group).

[0036] Specific examples of the structure containing a reversible thermally dissociable structure include, for example, one or more of the following (d1) to (d4). These structures are basically dissociated by heat alone without the aid of a catalyst or reactant, and the dissociation reaction also proceeds in bulk (solvent-free), so they are preferred thermally dissociable structures in this embodiment. The fact that no catalyst or reactant is required is preferable in terms of, for example, improving the storage stability of the dismantlable adhesive material before application to adhesion, and suppressing unintended deterioration of adhesiveness. (d1) Diels-Alder adduct structure (d2) Disulfide structure (d3) Imidazole-1-carboxamide structure (d4) N-heterocyclic carbene dimer structure

[0037] (d1) The Diels-Alder adduct structure has already been partially explained in Figs. 4, 5, and 6. The dissociation temperature T DIS is, for example, 80° C. to 160° C., specifically 90° C. to 150° C., and more specifically 110° C. to 130° C. The recombination temperature of the thermally dissociated Diels-Alder adduct structure is, for example, 60° C. to 80° C.

[0038] More specifically, the structure containing the thermally dissociable structure may contain any of the structures (partial structures) represented by the following general formulae (d1-1) to (d1-4). These structures are more specific examples of the Diels-Alder adduct structure of (d1) above.

[0039] [ka]

[0040] In the above general formulas (d1-1) to (d1-4), X represents a divalent or trivalent group; Y represents a divalent group; EWG stands for electron withdrawing group; Bonds represented by a combination of straight and dashed lines represent either single or double bonds; The wavy lines represent bonds to other atoms.

[0041] Examples of the divalent group of X include a linear or branched alkylene group, -O-, -S-, -NH-, -NR- (R: monovalent organic group), etc. The linear or branched alkylene group typically has 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms, and more preferably 1 carbon atom. The trivalent group of X may be, for example, a nitrogen atom. Examples of the divalent group for Y include a linear or branched alkylene group, an ether group (-O-), a sulfide group (-S-), etc. The linear or branched alkylene group typically has 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms, and more preferably 1 carbon atom. Examples of the EWG include an oxygen atom (=O), a fluorinated alkyl group, a halogeno group, a nitro group, and a cyano group.

[0042] The structures represented by general formulae (d1-1) to (d1-4) usually undergo a retro Diels-Alder reaction due to heat, and dissociate as shown in the following general formulae (d1-1') to (d1-4').

[0043] [ka]

[0044] In general formulae (d1-1') to (d1-4'), the definitions and specific examples of X, Y and EWG are the same as those in general formulae (d1-1) to (d1-4).

[0045] (d2) Regarding disulfide structures, bond dissociation occurs through the mechanism of the so-called disulfide exchange reaction. In other words, the cross-linked structure becomes weaker through the chemical reaction represented by the following reaction formula:

[0046] [ka]

[0047] In the above, R 41 From R 44 each independently represents a chemical structure in the cured product. The disulfide exchange reaction usually proceeds at about 70°C. For disulfide exchange reactions, see, for example, ACS Appl. Mater. Interfaces 2012, 4, 11, 6280-6288.

[0048] The (d3) imidazole-1-carboxamide structure can specifically be a structure represented by the following chemical formula (d3-1).

[0049] [ka]

[0050] In the above chemical formula, the wavy lines represent bonds to other atoms.

[0051] The above structure is usually thermally dissociated into an imidazole structure and an isocyanate structure at temperatures of 150°C or higher, as shown in the following chemical reaction formula. Recombination can occur at temperatures between 60°C and 70°C.

[0052] [ka]

[0053] In the above chemical formula, the wavy lines represent bonds to other atoms.

[0054] The N-heterocyclic carbene dimer structure (d4) can specifically be a structure represented by the following chemical formula (d4-1).

[0055] [ka]

[0056] In the chemical formula (d4-1), each of the four R independently represents a monovalent organic group, and the wavy lines represent bonds to other atoms. Specific examples of the monovalent organic group include alkyl groups having 1 to 6 carbon atoms.

[0057] The above structure usually undergoes thermal dissociation at a temperature of 100° C. or higher, as represented by the following chemical formula. The definitions of R and the wavy line are the same as those in chemical formula (d4-1).

[0058] [ka]

[0059] For the (d3) imidazole-1-carboxamide structure and (d4) N-heterocyclic carbene dimer structure, see MACROMOLECULES vol. 43, 6 (2010) 2643-2653.

[0060] The thermosetting resin can contain a thermally dissociable compound having a thermally dissociable structure in either of the following modes (i) or (ii). (i) When the curing component contains a curing agent, one or both of the epoxy resin and the curing agent contain a thermally dissociable compound. (ii) When the curing component does not include a curing agent, the epoxy resin includes a thermally dissociable compound.

[0061] That is, in the thermosetting resin, the epoxy resin, which is the main component constituting the cured product, or the curing agent contains a thermally dissociable compound. In the above case of (i), the thermally dissociable compound may be contained in only one of the epoxy resin and the curing agent, or may be contained in both. A preferred example is one in which the base resin contains an epoxy resin and a curing agent, and at least the epoxy resin contains a thermally dissociable compound.

[0062] [Epoxy resin] The epoxy resin in this embodiment may contain a thermally dissociable compound. The epoxy resin in this embodiment may be in any of the following forms (i) to (iii). (i) An embodiment including an epoxy resin (a1) containing a thermally dissociable structure and an epoxy resin (a2) not containing a thermally dissociable structure (ii) An embodiment including only the epoxy resin (a1) having a thermally dissociable structure (iii) An embodiment including only an epoxy resin (a2) that does not contain a thermally dissociable structure

[0063] The epoxy resin (a1) containing a thermally dissociable structure may contain only one thermally dissociable structure in the molecule, or may contain two or more (e.g., 2 to 4) thermally dissociable structures in the molecule. It is believed that the epoxy resin (a1) containing two or more thermally dissociable structures in the molecule can provide better dismantling properties.

[0064] The epoxy resin (a1) containing a thermally dissociable structure can be, for example, an epoxy resin containing one or more structures selected from the group consisting of the above-mentioned (d1) Diels-Alder adduct structure, (d2) disulfide structure, (d3) imidazole-1-carboxamide structure, and (d4) N-heterocyclic carbene dimer structure.

[0065] The epoxy resin (a1) containing a thermally dissociable structure is preferably one represented by the following general formula (a1-1).

[0066] [ka]

[0067] In general formula (a1-1), n is an integer of 2 or more, L represents a single bond or a divalent linking group. A represents an n-valent organic group containing a thermally dissociable structure.

[0068] n is preferably an integer from 2 to 6, and more preferably an integer from 2 to 4. The divalent linking group of L is not particularly limited. L may be an alkylene group, a cycloalkylene group, an arylene group, an ether group, a carbonyl group, a carboxy group (-COO or -OCO-), a sulfide group, or a divalent group formed by linking two or more groups selected from these groups. L is, for example, a divalent organic group having 1 to 10 carbon atoms. There are n L's in the general formula (a1-1), and these L's may be the same or different from each other. Examples of the thermally dissociable structure contained in A include one or more structures selected from the group consisting of the above-mentioned (d1) Diels-Alder adduct structure, (d2) disulfide structure, (d3) imidazole-1-carboxamide structure, and (d4) N-heterocyclic carbene dimer structure. A may contain only one thermally dissociable structure, or may contain two or more.

[0069] The epoxy resin (a1) containing a thermally dissociable structure is more preferably one represented by the following general formula (a1-2) or (a1-3).

[0070] [ka]

[0071] In general formulae (a1-2) and (a1-3), The definitions and specific examples of X, Y, and EWG are the same as those in the above-mentioned general formulae (d1-1) to (d1-4), except that in the general formula (a1-3), two Xs each independently represent a trivalent group (e.g., a nitrogen atom), The definition and specific examples of L are the same as those in general formula (a1-1). Each n is independently an integer of 1 or more, preferably an integer of 1 to 3, and more preferably 1 or 2.

[0072] Examples of the epoxy resin (a1) containing a thermally dissociable structure include the following. For reference, the CAS registry number of each epoxy resin is also shown. Regarding the epoxy resin with CAS registration number 1642327-20-5, the literature in which the resin is described reports that the Diels-Alder reaction proceeds at a heating temperature of 78°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 115°C. Regarding the epoxy resin with CAS registration number 630109-37-4, the literature in which the resin is described reports that the Diels-Alder reaction proceeds at a heating temperature of 75°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 95°C. Regarding the epoxy resin with CAS registration number 451456-99-8, the literature in which the resin is described reports that the Diels-Alder reaction proceeds at a heating temperature of 75°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 95°C. Regarding the epoxy resin with CAS registration number 1354635-72-5, the literature in which the resin is described reports that the Diels-Alder reaction proceeds at a heating temperature of 60°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 104°C. Regarding the epoxy resin with CAS registration number 1142408-09-0, it has been reported in the literature where the resin is described that the Diels-Alder reaction proceeds at a heating temperature of 60 °C and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 111 °C.

[0073]

Chemical formula

[0074]

Chemical formula

[0075]

Chemical formula

[0076]

Chemical formula

[0077]

Chemical formula

[0078]

Chemical formula

[0079]

Chemical formula

[0080]

Chemical formula

[0081]

Chemical formula

[0082] The synthesis method of the epoxy resin (a1) containing a thermally dissociable structure is not particularly limited. For specific examples of the synthesis method, please refer to the examples below. In addition, based on the CAS registration numbers of the specific compounds described above, the synthesis methods in the literature in which each compound is described can also be referenced.

[0083] The epoxy resin (a2) not containing a thermally dissociable structure may be any known one without particular limitation, such as glycidyl ethers of bisphenol A type, F type, S type, AD type, etc., phenol novolac type glycidyl ether, cresol novolac type glycidyl ether, bisphenol A type novolac type glycidyl ether, naphthalene type glycidyl ether, biphenol type glycidyl ether, dihydroxypentadiene type glycidyl ether, triphenylmethane type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, etc.

[0084] In addition, the epoxy resin (a2) not containing a thermally dissociable structure may be an alicyclic epoxy compound. Specifically, hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-1-methylcyclohexyl-3,4-epoxy-1-methylhexane carboxylate, 6-methyl-3,4-epoxycyclohexylmethyl-6-methyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-3-methylcyclohexylmethyl-3,4-epoxy-3-methylcyclohexane carboxylate, 3,4-epoxy-5-methylcyclohexylmethyl-3,4-epoxy-5-methylcyclohexane carboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-metadioxane, bis(3,4-epoxycyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexylcarboxylate, methylene bis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene bis(3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1-epoxyethyl-3,4-epoxycyclohexane, 1,2-epoxy-2-2-epoxyethylcyclohexane, and the like. Commercially available alicyclic epoxy compounds include, for example, the "Celloxide" series manufactured by Daicel Corporation.

[0085] [Hardening agent] The curing agent in this embodiment may contain a thermally dissociable compound. The curing agent in this embodiment may be in any of the following forms (i) to (iii). (i) An embodiment including a curing agent (b1) containing a thermally dissociable structure and a curing agent (b2) not containing a thermally dissociable structure (ii) An embodiment including only the curing agent (b1) having a thermally dissociable structure (iii) An embodiment including only a curing agent (b2) that does not contain a thermally dissociable structure

[0086] The curing agent (b1) containing a thermally dissociable structure can be, for example, a curing agent containing one or more structures selected from the group consisting of the above-mentioned (d1) Diels-Alder adduct structure, (d2) disulfide structure, (d3) imidazole-1-carboxamide structure, and (d4) N-heterocyclic carbene dimer structure.

[0087] The curing agent (b1) containing a thermally dissociable structure is preferably represented by the following general formula (b1-1).

[0088] [ka]

[0089] In general formula (b1-1), The definitions and specific examples of n, A and L are the same as those of general formula (a1-1). Z is at least one selected from the group consisting of an amino group, a hydroxy group, and a carboxy group. In general formula (b1-1), a plurality of Z may be present, and the plurality of Z may be the same or different.

[0090] The curing agent (b1) containing a thermally dissociable structure is more preferably one represented by the following general formula (b1-2) or (b1-3).

[0091] [ka]

[0092] In general formulae (b1-2) and (b1-3), the definitions and specific examples of X, Y, and EWG are the same as those in general formulae (d1-1) to (d1-4) described above, except that two Xs in general formula (b1-3) each independently represent a trivalent group (e.g., a nitrogen atom), The definition and specific examples of L are the same as those in the above general formulae (a1-1) and (b1-1). The definition and specific examples of Z are the same as those in general formula (b1-1) above. Each n is independently an integer of 1 or more, preferably an integer of 1 to 3, and more preferably 1 or 2.

[0093] Examples of the curing agent (b1) containing a thermally dissociable structure include the following. For reference, the CAS registry number of each curing agent is also shown. Regarding the curing agent with CAS registration number 1629090-33-0, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 78°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 120°C. Regarding the curing agent with CAS registration number 1629090-36-3, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 90°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 120°C. Regarding the curing agent with CAS registration number 2170611-60-4, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 65°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 150°C. Regarding the curing agent with CAS registration number 1449422-51-8, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 70°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 150°C. Regarding the curing agent with CAS registration number 1438275-50-3, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 40°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 110°C. Regarding the curing agent with CAS registration number 2131218-36-3, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 65°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 120°C. Regarding the curing agent with CAS registration number 2270969-71-4, the literature in which this is described reports that the Diels-Alder reaction proceeds at a heating temperature of 65° C. (the heating temperature for the retro-Diels-Alder reaction is not described). Regarding the curing agent having CAS registration number 2363046-97-1, the literature in which this is described reports that the Diels-Alder reaction proceeds at room temperature (the heating temperature for the retro-Diels-Alder reaction is not described). Regarding the curing agent with CAS registration number 1788898-24-7, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 60°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 90 to 97°C. Regarding the curing agent with CAS registration number 1280739-86-7, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 65°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 130°C. Regarding the curing agent with CAS registration number 107958-95-2, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 80°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 129 to 140°C. Regarding the curing agent with CAS registration number 1438275-48-9, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 40°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 110°C. Regarding the curing agent with CAS registration number 1869990-66-8, the literature in which it is described reports that the Diels-Alder reaction proceeds at a heating temperature of 70°C, and the retro-Diels-Alder reaction (i.e., thermal dissociation) proceeds at a heating temperature of 120°C.

[0094] [ka]

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[0105] As the curing agent (b2) that does not contain a thermally dissociable structure, any one can be selected. Preferred examples of the curing agent (b2) include compounds having an amino group, a carboxyl group, or a hydroxyl group as a group reactive with an epoxy group. The compound used as the curing agent is at least one polyamine compound selected from the group consisting of aliphatic polyamine compounds, aromatic polyamine compounds, and alicyclic polyamine compounds, and is preferably a polyamine compound having two or more primary amino groups.

[0106] Examples of aliphatic polyamine compounds having two or more primary amino groups include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,3-diaminobutane, 1,4-diaminobutane, diethylenetriamine, triethylenetriamine, tetraethylenepentamine, 2,2,4-trimethylhexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine.

[0107] Examples of aromatic polyamine compounds having two or more primary amino groups include m-xylylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

[0108] Examples of alicyclic polyamine compounds having two or more primary amino groups include 1,2-diaminocyclohexane, 1,4-diamino-3,6-diethylcyclohexane, isophoronediamine, menthanediamine, and 1,3-bisaminocyclohexane.

[0109] Examples of compounds other than those mentioned above include dicyandiamide, acid anhydrides, dibasic acid dihydrazides (oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, phthalic acid dihydrazide, etc.), and melamine.

[0110] When the easily dismantlable adhesive material is a one-liquid adhesive material, it is preferable to use a so-called latent curing agent as the curing agent. The latent curing agent does not react when present in the epoxy resin at room temperature, but is activated by heat treatment and starts to react. The microcapsule type latent curing agent is a particle having a shell part and a core part, and the curing agent is contained in the core part. By heat treatment at a predetermined temperature or higher, a part of the shell part breaks and the curing agent inside flows out, activating the reactivity with the epoxy group. Examples of products of the microcapsule type latent curing agent include Novacure (registered trademark) HX-3722, HX-3748, HX-3088, HX-3741, HX-3742, etc. manufactured by Asahi Kasei Corporation.

[0111] [Cure accelerator] In this embodiment, a curing accelerator may or may not be used. When using a curing accelerator, the type and amount of the curing accelerator may be appropriately selected. Examples of the curing accelerator include imidazoles, organic phosphorus compounds, organic metal salts, tertiary amines, phenol compounds, and organic acids. These may be used alone or in combination of two or more. Among these, from the viewpoint of heat resistance, at least one selected from the group consisting of organic phosphorus compounds, complexes of organic phosphorus compounds and organic boron compounds, and compounds having intramolecular polarization formed by adding a compound having a π bond to an organic phosphorus compound may be used. Examples of compounds having a π bond include maleic anhydride, quinone compounds, diazophenylmethane, and phenol resins. In addition, quaternary phosphonium salt compounds, quaternary ammonium salt compounds, fatty acid salt compounds, metal chelate compounds, and metal salt compounds may be used. Further, a latent curing accelerator such as a dihydrazide compound such as dicyandiimide or adipic acid dihydrazide, guanamic acid, melamine acid, an addition compound of an epoxy compound and an imidazole compound, an addition compound of an epoxy compound and a dialkylamine, an addition compound of an amine and a thiourea, or an addition compound of an amine and an isocyanate may be used.

[0112] [Thermal expansion particles] The thermally expandable particles that can be used in the present embodiment are not particularly limited. As described above, any thermally expandable particles can be used as long as they can provide the effect of easy dismantling due to the synergistic effect with the dissociation of the thermally dissociable structure. The thermally expandable particles are typically thermally expandable microcapsules having a polymeric shell and a core containing a volatile expansion agent.

[0113] FIG. 7 is a diagram for explaining the thermally expandable microcapsules. The shell of the thermally expandable microcapsule is usually made of a thermoplastic resin, and is preferably made of a polymer obtained by polymerizing a monomer mixture containing one or more polymerizable monomers selected from the group consisting of acrylonitrile, methacrylonitrile, and vinylidene chloride. The core in the thermally expandable microcapsules usually contains a volatile organic substance such as an organic solvent, specifically a hydrocarbon having a relatively low boiling point (liquid at 25° C.), as a volatile expansion agent. When a microcapsule having such a shell and core is heated, the shell softens and the hydrocarbon in the core vaporizes. The pressure of the vaporization causes the capsule to expand. Depending on the type of microcapsule, some known thermally expandable microcapsules can expand in volume by up to 50 to 100 times.

[0114] In this embodiment, the expansion start temperature T INI (sometimes referred to as the foaming initiation temperature) and the dissociation temperature T DIS By appropriately setting the relationship, it is possible to further enhance the synergistic effect between the bond dissociation and the expansion of the thermally expandable particles. Specifically, (T INI -T DIS ) is preferably -20°C or higher and 20°C or lower, more preferably -15°C or higher and 15°C or lower, and even more preferably -10°C or higher and 10°C or lower. INI and T DISSince the temperatures are almost the same, the heat-expanding particles expand almost simultaneously with the dissociation of the heat-dissociable structure during the heat treatment at the time of dismantling, and the hardened body is effectively weakened. This effect is particularly remarkable when a reversible heat-dissociable structure is used as the heat-dissociable structure.

[0115] The expansion start temperature T of the thermally expandable particles INI is preferably 100°C or higher and 150°C or lower, more preferably 110°C or higher and 140°C or lower, and further preferably 120°C or higher and 135°C or lower. T INI By setting the temperature to 100°C or higher, the expansion of the thermally expandable particles at the heating temperature usually used for bonding (curing reaction of the epoxy resin) is substantially suppressed, so that reliable bonding can be achieved. INI By making the temperature 100° C. or higher, the heat resistance of the hardened body before dismantling can be further improved. T INI By keeping the temperature below 150°C, energy consumption during dismantling can be reduced.

[0116] Maximum expansion temperature T of the thermal expansion particles MAX is preferably 130°C or higher and 200°C or lower, more preferably 140°C or higher and 180°C or lower, and further preferably 145°C or higher and 170°C or lower. T MAX By setting the temperature at 130°C or higher, the expansion of the heat-expanding particles at the heating temperature usually used for bonding (curing reaction of epoxy resin) is sufficiently suppressed, making it easy to perform reliable bonding. In addition, the heat resistance of the cured body before dismantling can be increased. T MAX By keeping the temperature below 200°C, energy consumption during dismantling can be reduced.

[0117] The average particle diameter of the thermally expandable particles is not particularly limited. From the viewpoint of becoming sufficiently large upon thermal expansion, ensuring sufficient adhesion, and forming a smooth cured body, the average particle diameter of the thermally expandable particles (diameter at room temperature before expansion) is, for example, 5 μm or more and 50 μm or less, preferably 10 μm or more and 40 μm or less.

[0118] Expansion start temperature T INI , maximum expansion temperature T MAX A further explanation regarding the average particle size will be provided below. When using commercially available products as thermal expansion particles, the catalog or specifications do not include the INI , T MAX If the average particle size is listed, use that value as the T INI , T MAX In this case, if the values ​​given in the catalog or specifications have a range, the center value of the range is used. For example, if the catalog says T MAX If the temperature is stated as 175 to 185°C, MAX is assumed to be 180°C. From the catalog and specifications, INI Or T MAX If it is unclear, gradually heat the thermally expandable particles while observing them with an optical microscope, and measure the point at which the particles start to expand (the inflection point) as T INI The temperature at which the diameter is maximum is T MAX The average particle size can be determined by observing the thermally expandable particles with an optical microscope at room temperature (25° C.), measuring the diameters (circle equivalent diameters) of 100 or more particles, and averaging the number of diameters to obtain the average particle size.

[0119] As the thermally expandable particles, commercially available products can be used, such as Matsumoto Microsphere (registered trademark) series from Matsumoto Yushi Seiyaku Co., Ltd. and Kureha Microsphere series from Kureha Corporation.

[0120] In one embodiment, it is preferable to select a thermally expandable particle that has a high affinity with the thermosetting resin and is distributed substantially uniformly in the cured body, which is believed to weaken the entire cured body evenly during dismantling (suppressing the occurrence of incompletely weakened spots), resulting in stable dismantling. On the other hand, in another embodiment, it is possible to select heat-expanding particles that are unevenly distributed at the air-film interface or the film-adherend interface when the easily dismantled adhesive material is applied to the surface of the adherend to form a film. This is thought to enable the dismantling mode to be controlled in an interfacial peeling manner. This also allows the amount of heat-expanding particles to be reduced, which may lead to a reduction in the raw material cost of the dismantlable adhesive material.

[0121] [Filling material] The easily dismantlable adhesive material of the present embodiment may contain a filler, which, for example, makes the thermal expansion coefficients of the cured body and the adherend about the same, suppresses stress caused by temperature changes, and ultimately leads to stable adhesive strength before dismantling. Just to be clear, the filler is a different component from the thermally expandable particles.

[0122] The filler may be an organic filler, an inorganic filler, or a combination of these. Typically, the use of an inorganic filler is preferred. Examples of organic fillers include thermoplastic resins, thermoplastic elastomers, carbon fibers, cellulose, and polyethylene polypropylene powder. Examples of inorganic fillers include fused silica, crystalline silica, alumina, talc, silicon nitride, aluminum nitride, glass fiber, asbestos fiber, boron fiber, quartz powder, mineral silicates, mica, asbestos powder, and slate powder. When a filler is used, one type may be used alone, or two or more types may be used in combination.

[0123] [Other ingredients] The easily dismantlable adhesive material of the present embodiment may contain various components in addition to the thermosetting resin and the thermally expandable particles.

[0124] For example, the easily dismantled adhesive material of the present embodiment may contain an organic solvent. In other words, the easily dismantled adhesive material of the present embodiment may be one in which the epoxy resin and the curing component are dissolved or dispersed in an organic solvent, and the thermally expandable particles are dispersed. Examples of organic solvents include ketones such as acetone, methyl ethyl ketone (MEK), cyclohexanone, etc.; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, carbitol acetate, etc.; carbitols such as cellosolve, butyl carbitol, etc.; aromatic hydrocarbons such as toluene, xylene, etc.; chlorine-based solvents such as dichloromethane, dichloroethane, etc.; dimethylformamide (DMF), dimethylacetamide, N-methylpyrrolidone, etc.

[0125] Among the above, acetone, MEK, ethyl acetate, DMF, chlorine-based solvents, etc. are preferred because they have high solubility and tend to volatilize easily. As for the organic solvent, any one of them may be used alone, or two or more of them may be used in combination.

[0126] Examples of other optional components include inorganic particles such as silica and alumina, fiber fillers such as glass fibers and carbon fibers, thermoplastic elastomers, flame retardants, and defoamers.

[0127] The easily dismantled adhesive material of the present embodiment may contain a thermosetting resin other than an epoxy resin, such as bismaleimide, etc. The easily dismantled adhesive material of the present embodiment may also contain one or more of a silane coupling agent, a thermoplastic elastomer, a rubber component, an antifoaming agent, etc.

[0128] [Ratio of each component] When a curing agent is used, the mixing ratio of the epoxy resin to the curing agent (molar ratio of epoxy resin / curing agent) is from 1 / 0.01 to 1 / 10, more preferably from 1 / 0.03 to 1 / 10, and even more preferably from 1 / 0.05 to 1 / 10. In particular, when the curing agent is a compound having active hydrogen, such as a primary amine or secondary amine, a phenolic compound, a compound having a carboxylic acid group, or a thiol compound, it is preferable to mix the molar number of epoxy groups in the epoxy resin and the molar number of active hydrogen in the curing agent so that they are close to an equivalent ratio.For example, the ratio of epoxy groups to active hydrogen (molar number of epoxy groups / molar number of active hydrogen) is preferably 1 / 0.4 to 1 / 3, more preferably 1 / 0.7 to 1 / 2, and even more preferably 1 / 0.8 to 1 / 1.5.

[0129] As described above, the thermosetting resin may contain an epoxy resin (a2) that does not contain a thermally dissociable structure. Similarly, the curing agent may contain a curing agent (b2) that does not contain a thermally dissociable structure. From the viewpoint of obtaining good dismantling properties, it is preferable that the easily dismantled adhesive material of this embodiment contains an appropriate amount of a thermally dissociable compound. Specifically, when the mass of the epoxy resin (a1) containing a thermally dissociable structure in the easily dismantlable adhesive material is Ma1, the mass of the epoxy resin (a2) not containing a thermally dissociable structure is Ma2, the mass of the curing agent (b1) containing a thermally dissociable structure is Mb1, and the mass of the curing agent (b2) not containing a thermally dissociable structure is Mb2, the value of (Ma1+Mb1) / (Ma1+Ma2+Mb1+Mb2) is, for example, 0.01 or more, preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The upper limit of this value may be 1, but from the viewpoint of cost, etc., the upper limit is, for example, 0.8, preferably 0.5.

[0130] The amount of the thermally expandable particles is, for example, 1 part by mass or more and 50 parts by mass or less, preferably 3 parts by mass or more and 40 parts by mass or less, and more preferably 5 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the thermosetting resin. When the amount of the thermally expandable particles is 1 part by mass or more, the effect of easy dismantling can be sufficiently obtained. When the amount of the thermally expandable particles is 50 parts by mass or less, the adhesive strength before dismantling can be increased. It is also possible to adjust the balance between the adhesive strength before dismantling and the easy dismantling property by adjusting the amount of the thermally expandable particles.

[0131] [Physical properties of easily dismantled adhesive materials] In the easily dismantlable adhesive material of this embodiment, the ratio of F2 to F1 (F2 / F1) measured under the following conditions is preferably 0.9 or less, more preferably 0.8 or less. There is no particular restriction on the lower limit and it may be 0, but for example, 0.01 or more or 0.1 or more is sufficient. By doing so, it is possible to achieve a high level of both high adhesive strength during use and dismantlability that allows easy peeling with weak force.

[0132] (conditions) (i) Using SUS304 as the adherend, a sample in which two adherends are bonded together with the easily dismantlable adhesive material is subjected to measurement of the tensile shear adhesive strength in accordance with JIS K 6850:1999. (ii) The shear adhesive strength of sample 1 obtained by heat-treating the easily dismantlable adhesive material under the first heat treatment condition of 60°C for 7 hours is designated as F1, and the tensile shear adhesive strength of sample 2 obtained by heat-treating the easily dismantlable adhesive material under the first heat treatment condition and then heat-treating it under the second heat treatment condition of 140°C for 15 minutes is designated as F2.

[0133] The technical significance of the value of F2 / F1 is as follows. The value of F2 / F1 indicates the ease of dismantling by heating. F2 / F1 being smaller than 1 means that the tensile shear bond strength is reduced by heat treatment under the second heat treatment conditions. In adhesive materials using thermosetting resins, heat treatment at high temperatures generally promotes crosslinking of the thermosetting resin, improving the shear bond strength of the cured body. In contrast, the tensile shear bond strength of the easily dismantled adhesive material of this embodiment is reduced by heat treatment under the second heat treatment conditions. The value of F2 / F1 indicates the degree of this reduction, and the inventor has found that this value is an index of the ease of dismantling by heating. Assuming a structure in which two adherends are bonded using the easily dismantled adhesive material of this embodiment, thermal stress remains in the adhesive material layer due to the difference in linear expansion coefficient between the adhesive material layer and the adherends. For this reason, a certain degree of peeling action is inherently generated at the interface between the adhesive material layer and the adherends. In this state, by using an adhesive material in which F2 is lower than F1, particularly (F2 / F1) is preferably 0.9 or less, more preferably 0.8 or less, it is possible to realize sufficient ease of dismantling for practical use.

[0134] [Disassembly method] The easily dismantlable adhesive material of this embodiment is used in the following process, for example: (1) attach the easily dismantlable adhesive material to the surface of the adherend; (2) then heat-harden the easily dismantlable adhesive material to obtain a hardened body in which the hardened body of the easily dismantlable adhesive material is bonded to the adherend; and (3) then heat-treat to peel off the hardened body of the easily dismantlable adhesive from the adherend and dismantle it. If the temperature conditions used for the heat-hardening in (2) above are the first temperature conditions, and the temperature conditions used for the dismantling in (3) above are the second temperature conditions, it is preferable that the second temperature conditions have a higher hardening temperature than the first temperature conditions.

[0135] The type of the adherend is not particularly limited. For example, the adherend may be made of metals such as aluminum, aluminum alloys, and SUS, plastics such as polypropylene, polyethylene, and nylon, and ceramics. The adherend may be surface-treated with a silane coupling agent or the like, or may not be surface-treated. In terms of adhesive strength and ease of dismantling, it is preferable to remove foreign matter / contamination from the surface of the adherend by cleaning the surface of the adherend before attaching the easily dismantled adhesive to the surface of the adherend.

[0136] If the curing temperature under the first temperature condition is T1 and the curing temperature under the second temperature condition is T2, the value of (T2-T1) is preferably 30°C or more, more preferably 50°C or more, and most preferably 70°C or more. By doing so, sufficient strength of the cured body and ease of dismantling can be achieved. From the viewpoint of saving energy in the dismantling process, the upper limit of the value of (T2-T1) is preferably 130°C or less, and more preferably 120°C or less. In practical terms, it is preferable that T1 is 20°C or more and 100°C or less, and T2 is 100°C or more and 250°C or less. In other words, the dissociation temperature T of the thermally dissociable structure is set so that T1 and T2 (T2-T1) are realized. DIS , the expansion start temperature T of the thermally expandable particles INI , maximum expansion temperature T MAX It is preferable to adjust the above (and therefore to select an appropriate thermally dissociable structure or thermally expandable particles).

[0137] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. Below, examples of reference forms are given. 1. The thermosetting resin and the thermally expandable particles are included, The thermosetting resin is Epoxy resin, a curing component including one or both of a curing agent and a curing accelerator; Including, The thermosetting resin is an easily dismantlable adhesive material comprising a thermally dissociable compound having a thermally dissociable structure in either of the following embodiments (i) or (ii). (i) In the case where the curing component includes a curing agent, one or both of the epoxy resin and the curing agent include a thermally dissociable compound. (ii) When the curing component does not include a curing agent, the epoxy resin includes a thermally dissociable compound. 2. 1. The easily dismantlable adhesive material according to claim 1, The thermally dissociable compound is an easily dismantlable adhesive material having any one of the following thermally dissociable structures (d1) to (d4). (d1) Diels-Alder adduct structure (d2) Disulfide structure (d3) Imidazole-1-carboxamide structure (d4) N-heterocyclic carbene dimer structure 3. 1. An easily dismantlable adhesive material according to 1. or 2. The thermally dissociable structure is a reversible thermally dissociable structure that is dissociated by heat and then recombined when cooled to 25°C, and is an easily dismantlable adhesive material. 4. An easily dismantlable adhesive material according to any one of 1. to 3., The thermally dissociable structure comprises any of the structures represented by the above general formulas (d1-1) to (d1-4), and the easily dismantlable adhesive material. In general formulae (d1-1) to (d1-4), X represents a divalent or trivalent group; Y represents a divalent group; Each EWG independently represents an electron-withdrawing group; Bonds represented by a combination of straight and dashed lines represent either single or double bonds; The wavy lines represent bonds to other atoms. 5. An easily dismantlable adhesive material according to any one of 1. to 4., The easily dismantlable adhesive material, wherein the epoxy resin contains the thermally dissociable compound. 6. An easily dismantlable adhesive material according to any one of 1. to 5., The easily dismantlable adhesive material, wherein the thermally expandable particles are thermally expandable microcapsules having a shell made of a polymer and a core containing a volatile expansion agent. 7. An easily dismantlable adhesive material according to any one of 1. to 6., The expansion start temperature of the thermally expandable particles is T INI year, The dissociation temperature of the thermally dissociable structure is T DIS When (T INI -T DIS ) is an easily dismantlable adhesive material that has a temperature range of -20℃ or higher and 20℃ or lower. 8. An easily dismantlable adhesive material according to any one of 1. to 7., The expansion start temperature T INI An easily dismantlable adhesive material having a temperature of 100°C or higher. 9. An easily dismantlable adhesive material according to any one of 1. to 8., The maximum expansion temperature T MAX An easily dismantlable adhesive material having a temperature of 130°C or higher. 10. An easily dismantlable adhesive material according to any one of 1. to 9., The easily dismantlable adhesive material is attached to the surface of an adherend, a first heat treatment is performed to obtain a hardened body that bonds to the adherend, and then a second heat treatment is performed to the hardened body to dismantle the adherend and the hardened body. 11. An article comprising an adherend and a cured body of the easily dismantlable adhesive material according to any one of 1. to 10. bonded to the adherend. 12. 11. A dismantling method comprising a dismantling step of heating the article according to claim 11 to dismantle the adherend and the cured body of the easily dismantlable adhesive material.

[0138] [Example of compounding of easy-to-dismantle adhesive material] Some examples of compounding of easily dismantlable adhesive materials are shown below. (Combination example 1) A thermosetting resin containing a compound with CAS registration number 1426573 (a Diels-Alder adduct of furfurylamine and octamethylene bismaleimide) and bisphenol A diglycidyl ether in a molar ratio of 1:2, to which a thermally expandable microcapsule (such as that used in the examples below) was added at 20% by mass relative to the thermosetting resin. (Combination example 2) A thermosetting resin having a molar ratio of [a compound having CAS registration number 1426573 (a Diels-Alder adduct of furfurylamine and octamethylene bismaleimide)]:[octamethylenediamine]:[bisphenol A diglycidyl ether]=0.1:0.9:2, to which a thermally expandable microcapsule (such as that used in the examples below) was added at 20% by mass relative to the thermosetting resin. (Combination example 3) A thermosetting resin having a molar ratio of [a compound having CAS registration number 2170611-60-4 (a Diels-Alder adduct of furfurylamine and bismaleimide diphenylmethane)]:[octamethylenediamine]:[bisphenol A diglycidyl ether] = 0.1:0.9:2, to which a thermally expandable microcapsule (such as that used in the examples below) was added at 20% by mass relative to the thermosetting resin. (Combination example 4) A thermosetting resin containing a compound with CAS registration number 1009048-76-3 (a Diels-Alder adduct of furfuryl alcohol and 2-hydroxyethylmaleimide) in a molar ratio of 1:1 (bisphenol A diglycidyl ether) to which a thermally expandable microcapsule (such as that used in the examples below) was added at 20% by mass relative to the thermosetting resin. (Combination example 5) The same as Example 1 described later, except that the amount of the thermally expandable particles was changed to 10% by mass relative to the total amount (mass) of the epoxy compounds (BADGE and FDB). (Combination example 6) The same as Example 1 described later, except that the amount of the thermally expandable particles was changed to 5% by mass relative to the total amount (mass) of the epoxy compounds (BADGE and FDB). EXAMPLES

[0139] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. It should be noted that the present invention is not limited to the Examples.

[0140] <Synthesis of epoxy resin containing thermally dissociable structure> [reagent] Epichlorohydrin (>99%, Kishida Chemical Co., Ltd.), tetrabutylammonium bromide (TBAB,>99%, Tokyo Chemical Industry Co., Ltd.), furfuryl alcohol (>97%, Wako Pure Chemical Industries, Ltd.), sodium hydroxide (>93%, Wako Pure Chemical Industries, Ltd.), 4,4'-bismaleimidediphenylmethane (>96%, Tokyo Chemical Industry Co., Ltd.), ethylene glycol diglycidyl ether (EGDGE, purity not stated, Tokyo Chemical Industry Co., Ltd.), and diethylenetriamine (DETA>98%, Tokyo Chemical Industry Co., Ltd.) were used as they were commercially available. Tetrahydrofuran (THF) was purified by distillation. Other solvents and reagents were used as they were commercially available.

[0141] [Synthesis of furfuryl glycidyl ether (FGE)] 51 g (0.55 mol) of epichlorohydrin and 3.8 g (1.18 × 10 -2 The mixture was stirred and mixed. After 15 minutes of nitrogen replacement, 49 g (0.50 mol) of furfuryl alcohol was added dropwise at room temperature over 30 minutes under a nitrogen atmosphere, and the mixture was stirred at room temperature for 2 hours. Then, approximately 80 mL of an aqueous NaOH solution prepared in advance from 40 g (1.0 mol) of NaOH was added dropwise at room temperature within 1 hour, and the mixture was stirred for 2 hours. Approximately 100 mL of diethyl ether was added to extract the organic layer, which was washed three times with approximately 50 mL of distilled water. The organic layer was then dried over anhydrous sodium sulfate, and the diethyl ether was removed using an evaporator to obtain a brown liquid. This liquid was distilled under reduced pressure in an oil bath, and a colorless, transparent liquid FGE with a base pressure of 103-105°C / 11 mmHg was isolated. The isolated FGE 1 The H NMR spectrum is shown in Figure 8. The yield and mass were 16 g and 21%. Furfuryl glycidyl ether (FGE): 1 H NMR (300 MHz, CDCl 3 ):δ 7.44-7.39(m,1H),6.38-6.31(m,2H),4.53(q,J=12.8Hz,2H),3.75(J=11.5,3.1Hz,1H),3.44(J= 11.5,5.8Hz,1H),3.16(J=5.8,4.0,2.9Hz,1H),2.80(J=9.2,4.4Hz,1H),2.61(J=5.0,2.7Hz,1H)

[0142] For reference, the above reaction scheme is shown below.

[0143] [ka]

[0144] [Synthesis of 2,2'-(methylenebis(4,1-phenylene))bis(4-((oxiran-2-ylmethoxy)methyl)-3a,4,7,7a-tetrahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione) (FDB)] 7.14 g (0.02 mol) of 4,4'-bismaleimidodiphenylmethane (bisM) was dissolved in 50 mL of distilled THF with stirring. After 15 minutes of nitrogen replacement, 6.16 g (0.04 mol) of FGE was added dropwise at room temperature under a nitrogen atmosphere and refluxed for 24 hours. The reaction solution was added dropwise to an excess amount (approximately 600 mL) of diethyl ether, and the resulting yellow-white precipitate was suction filtered and dried overnight under reduced pressure. This was purified by silica gel column chromatography (chloroform:acetone = 10:3 (v / v)), and a colorless, transparent solid, FDB, was isolated in a yield of 7.3%. The isolated FDB 1 The H NMR spectrum is shown in Figure 9. Peaks assigned to the protons (e, e', f, g) specific to the DA adduct were observed in the spectrum, and the integrated intensity ratio of the peaks assigned to each proton of FDB roughly matched the theoretical value (a:b:c:d:e:f:g:h:i:j=1.98:1.01:2.07:2.01:2.07:1.00:2.10:2.12:2.07:1.06), indicating that the synthesis and isolation of FDB had been achieved. 2,2'-(methylenebis(4,1-phenylene))bis(4-((oxiran-2-ylmethoxy)methyl)-3a,4,7,7a-tetrahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione) (FDB): 1 H NMR(300MHz,DMSO-d6): δ7.39-7.32(2H),7.15(2H),6.57(2H),5.21(1H),4.23(2H),4.08-3.98(1H),3.85 -3.75(2H),3.36-3.32(1H),3.19(1H),3.06(1H),2.74-2.68(1H),2.56-2.51(1H)

[0145] For reference, the above reaction scheme is shown below.

[0146] [ka]

[0147] The dissociation temperature of the Diels - Alder adduct structure in the above - mentioned FDB, which is determined by differential scanning calorimetry at a heating rate of 10°C / min, is 127°C.

[0148] <Preparation of Thermally Expandable Particles> Matsumoto Microsphere (registered trademark) FN - 100MD manufactured by Matsumoto Yushi - Seiyaku Co., Ltd. was used. The following table shows the general properties of this thermally expandable particle described in the company's materials.

[0149]

Table 1

[0150] <Example 1: Preparation of Adhesive Material, Evaluation of Adhesiveness and Disintegrability> Bisphenol A diglycidyl ether (BADGE), a commercially available epoxy resin, the above - obtained FDB, DETA, and the thermally expandable particle FN - 100MD were mixed in a dichloromethane / 1,2 - dichloroethane = 2 / 1 (v / v) mixed solvent. Then, a liquid adhesive material was prepared. The ratios of each component were as follows. [BADGE + FDB]:[DETA]=5:2 (molar ratio) BADGE / FDB = 70 / 30 (w / w) Amount of thermally expandable particles: 20% by mass based on the total amount (mass) of the epoxy compounds (BADGE and FDB) Amount of mixed solvent: Approximately 3.7 times the total amount (mass) of BADGE, FDB, and DETA

[0151] The evaluation of adhesiveness and disintegrability was carried out by preparing test joints as follows. For multiple evaluations, a plurality of identical test joints were prepared. (1) The above-prepared easy-to-dismantle adhesive material was dropped onto an aluminum plate or a stainless steel (SUS304) plate measuring 100 mm in length, 10 mm in width, and 1 mm in thickness, and spread over an area of ​​10 mm x 10 mm at the edge to prepare a test specimen. The amount of easy-to-dismantle adhesive material applied was set so that the adhesion amount after hardening was 6.2 mg for the aluminum plate and 6.5 mg for the stainless steel plate. (2) The mixture was dried at room temperature under reduced pressure for 3 hours, and the solvent was removed by distillation. (3) The test pieces were attached to each other over the 10 mm x 10 mm area where the easily dismantlable adhesive material was spread in (1) above, and secured in place with clips. (4) The test pieces were heated at 60° C. for 7 hours in a thermostatic chamber (first heat treatment) to harden the easily dismantlable adhesive material to bond the test pieces together, and then cooled to room temperature. In this way, a test bonded body was obtained. (5) A tensile shear test was carried out on the test joint obtained in (4) above. (6) The test joint obtained in (4) above (different from that used in (5) above) was heated at 140°C for 15 minutes (second heat treatment), cooled to room temperature, and then subjected to a tensile shear test.

[0152] The tensile shear tests in (5) and (6) above were conducted in accordance with JIS K 6850:1999 by pulling the bonded body in the vertical direction at a speed of 1 mm / min. The horizontal axis represents the pulling length (unit: mm) and the vertical axis represents the force required for pulling (unit: N) per 100 mm2 of the bonded surface area. 2 The SS curve was plotted by dividing the value by (unit: MPa).

[0153] The tensile shear test in (5) above and the tensile shear test in (6) above were performed three times each on the aluminum plate and the SUS304 plate. The SS curves obtained for the aluminum plate and the SUS304 plate are shown in Figure 10. In Figure 10, the three curves marked with an * are the SS curves obtained in the tensile shear test in (5) above, and the other three curves are the SS curves obtained in the tensile shear test in (6) above (the same applies to Figure 11 and subsequent figures). Figure 10 also lists the following values: (i) The value of the tensile shear bond strength when only the first heat treatment is performed as the heat treatment, specifically, the value of the tensile shear bond strength obtained in the tensile shear test in (5) above (average value of three tests, 4.43±0.34 MPa for aluminum, 2.50±0.20 MPa for stainless steel). (ii) The value of the tensile shear bond strength when the first heat treatment and the second heat treatment are performed as heat treatments, specifically, the value of the tensile shear bond strength obtained in the tensile shear test in (6) above (average value of three tests, 1.95±0.73 MPa for aluminum, 0.89±0.33 MPa for stainless steel). (iii) The rate of decrease (%) in the tensile shear adhesive strength, specifically, the negative value calculated by {1-(the value in (ii) above / the value in (i) above)} x 100 (-56% for aluminum, -64% for stainless steel)

[0154] As shown in Figure 10, by using an adhesive material containing FDB, a heat-dissociable compound having a heat-dissociable structure, and thermally expandable particles, a bonded body in which metal plates are bonded sufficiently strongly to each other can be obtained. In addition, by heating the bonded body at 140°C (second heat treatment), the tensile shear adhesive strength can be reduced to less than half. In other words, it is possible to achieve both high adhesive strength and dismantling ability that allows easy peeling with little force.

[0155] <Reference example: Heating temperature and ease of dismantling (heat resistance evaluation)> Except for the condition of the second heat treatment being 120°C for 60 minutes, the adhesiveness and ease of dismantling were evaluated in the same manner as in Example 1 when an aluminum plate was used as the metal plate. In this evaluation, the decrease in tensile shear adhesive strength due to the second heat treatment was 4%. In other words, the bonding strength was maintained at 96%. This suggests that disintegrability was not observed when heated at 120°C, which is lower than the dissociation temperature of the Diels-Alder adduct structure derived from FDB (130°C) and lower than the expansion onset temperature of the thermally expandable particles (125-135°C). Furthermore, from these results, it can be said that the adhesive material of Example 1 is an adhesive material with good heat resistance, in which disintegration at high temperatures of about 120°C is suppressed.

[0156] Comparative Example 1: Preparation of adhesive material, and evaluation of adhesion and ease of dismantling Comparative Example 1 is an example in which a thermally dissociable compound was used but no thermally expandable particles were used. Specifically, except that the thermally expandable particles were not added when preparing the easily dismantled adhesive material, the adhesive material was prepared and the adhesiveness and ease of dismantling were evaluated (SS curves were obtained) in the same manner as in Example 1. However, the amount of coating was set so that the adhesion amount after curing was 3.8 mg in the case of the aluminum plate and 2.8 mg in the case of the stainless steel plate.

[0157] The SS curves obtained for the aluminum plate and the stainless steel plate are shown in Figure 11. As in Figure 10, Figure 11 also shows (i) the value of the tensile shear bond strength when only the first heat treatment was performed as the heat treatment, (ii) the value of the tensile shear bond strength when the first heat treatment and the second heat treatment were performed as the heat treatment, and (iii) the rate of decrease (%) of the tensile shear bond strength.

[0158] As shown in Figure 11, when a joint was created by joining metal plates using an adhesive material that contained FDB, a thermally dissociable compound with a thermally dissociable structure, but did not contain thermally expandable particles, the tensile shear adhesive strength could not be sufficiently reduced even when the joint was heated to 140°C. It is presumed that although the Diels-Alder adduct structure derived from FDB was dissociated by heating at 140°C, it was rebonded by subsequent cooling, which is why sufficient dismantling ability was not achieved.

[0159] Comparative Example 2: Preparation of adhesive material, and evaluation of adhesion and ease of dismantling Comparative Example 2 is an example in which the thermally expandable particles were used but the thermally dissociable compound was not used. A liquid adhesive material was prepared by mixing a commercially available epoxy resin, ethylene glycol diglycidyl ether (EGDEG), DETA, and thermally expandable particles FN-100MD in a dichloromethane / 1,2-dichloroethane = 2 / 1 (v / v) mixed solvent. The ratio of each component was as follows: [EGDEG]:[DETA]=5:2 (molar ratio) Amount of thermally expansive particles: 20% by mass based on the amount (mass) of EGDEG Amount of mixed solvent: Approximately 3.7 times the total amount (mass) of EGDEG and DETA

[0160] Using the adhesive material prepared above, a bonded body was produced using aluminum plates in the same manner as in Example 1, and the adhesiveness and ease of dismantling were evaluated. The amount of coating was approximately the same as in Example 1 and Comparative Example 1. The obtained SS curves are shown in FIG. 12. In FIG. 12, as in FIGS. 10 and 11, (i) the value of the tensile shear adhesive strength when only the first heat treatment was performed as the heat treatment, and (ii) the value of the tensile shear adhesive strength when the first heat treatment and the second heat treatment were performed as the heat treatment are shown.

[0161] 12, when a bonded body was created by bonding metal plates together using an adhesive material that contained thermally expandable particles but did not contain a thermally dissociable structure, the tensile shear adhesive strength could not be reduced even when the bonded body was heated at 140° C. In particular, in the case of Comparative Example 2, it is presumed that the thermally expandable particles were hardly able to expand because the network structure in the hardened body was dense due to the use of DETA as a curing agent.

[0162] <Summary> The reduction rates of the tensile shear adhesive strength due to the second heat treatment in Example 1, Comparative Example 1, and Comparative Example 2 (where an aluminum plate was used as the metal plate) are summarized in the bar graph of Figure 13. In this bar graph, the "negative sign" of the reduction rate is not shown. It can be seen from the graph that "both" the thermal dissociation action of the thermally dissociable structure and the expansion action of the thermally expandable particles are necessary for good easy dismantling properties.

[0163] This application claims priority based on Japanese Patent Application No. 2020-102098, filed on June 12, 2020, the disclosure of which is incorporated herein in its entirety.

Claims

1. The thermosetting resin and the thermally expandable particles are included, The thermosetting resin is Epoxy resin, a curing component including one or both of a curing agent and a curing accelerator; Including, The thermosetting resin is an easily dismantlable adhesive material containing a thermally dissociable compound having a thermally dissociable structure in either of the following (i) or (ii): (i) In the case where the curing component includes a curing agent, one or both of the epoxy resin and the curing agent include a thermally dissociable compound. (ii) When the curing component does not include a curing agent, the epoxy resin includes a thermally dissociable compound. The thermally dissociable compound has (d1) a Diels-Alder adduct structure as the thermally dissociable structure, At a second temperature higher than a first temperature at which the thermosetting resin hardens, the thermal dissociation of the thermally dissociable structure and the expansion of the thermally expandable particles proceed substantially simultaneously, and the thermally expanded thermally expandable particles separate the thermally dissociated portion of the thermosetting resin; The easily dismantlable adhesive material, in which the thermally dissociated portions remain separated when the thermosetting resin is cooled to room temperature.

2. The easily dismantlable adhesive material according to claim 1, The easily dismantlable adhesive material has a reversible thermally dissociable structure that is dissociated by heat and then recombines when cooled to 25°C.

3. The easily dismantlable adhesive material according to claim 1 or 2, The thermally dissociable structure comprises any one of structures represented by the following general formulas (d1-1) to (d1-4), 【Chemistry 1】 In general formulas (d1-1) to (d1-4), X represents a divalent or trivalent group; Y represents a divalent group; Each EWG independently represents an electron-withdrawing group; Bonds represented by a combination of straight and dashed lines represent either single or double bonds; The wavy lines represent bonds to other atoms.

4. The easily dismantlable adhesive material according to any one of claims 1 to 3, The easily dismantlable adhesive material, wherein the epoxy resin contains the thermally dissociable compound.

5. An easily dismantlable adhesive material according to any one of claims 1 to 4, The easily dismantlable adhesive material comprises an epoxy resin having a thermally dissociable structure represented by the following general formula (a1-2) or (a1-3): 【Chemistry 2】 In general formulae (a1-2) and (a1-3), X represents a divalent or trivalent group; Y represents a divalent group; Each EWG independently represents an electron-withdrawing group; L represents an alkylene group, a cycloalkylene group, an ether group, a carbonyl group, a carboxy group (-COO or -OCO-), a sulfide group, or a divalent group formed by linking two or more groups selected from these groups; L′ represents a single bond or a divalent group; Bonds represented by a combination of straight and dashed lines represent either single or double bonds; Each n is independently an integer of 1 or more.

6. The easily dismantlable adhesive material according to any one of claims 1 to 5, The easily dismantlable adhesive material, wherein the thermally expandable particles are thermally expandable microcapsules having a shell made of a polymer and a core containing a volatile expansion agent.

7. The easily dismantlable adhesive material according to any one of claims 1 to 6, The expansion start temperature of the thermally expandable particles is T ＩＮＩ year, The dissociation temperature of the thermally dissociable structure is T ＤＩＳ When (T ＩＮＩ -T ＤＩＳ ) is an easily dismantlable adhesive material having a temperature of -20°C or higher and 20°C or lower.

8. The easily dismantlable adhesive material according to any one of claims 1 to 7, The expansion start temperature T ＩＮＩ The easily dismantlable adhesive material has a temperature of 100°C or higher.

9. The easily dismantlable adhesive material according to any one of claims 1 to 8, The maximum expansion temperature T ＭＡＸ The easily dismantlable adhesive material has a temperature of 130°C or higher.

10. An easily dismantlable adhesive material according to any one of claims 1 to 9, An easily dismantlable adhesive material having a ratio of F2 to F1 (F2 / F1) of 0.8 or less, as measured under the following conditions. (conditions) (i) Using SUS304 as the adherend, a sample is prepared by bonding two adherends together with the easily dismantlable adhesive material, and the tensile shear adhesive strength is measured in accordance with JIS K 6850:1999. (ii) The tensile shear adhesive strength of sample 1 obtained by heat-treating the easily dismantlable adhesive material under the first heat treatment condition of 60°C for 7 hours and then cooling to room temperature is designated as F1, and the tensile shear adhesive strength of sample 2 obtained by heat-treating the easily dismantlable adhesive material under the first heat treatment condition, then heat-treating it under the second heat treatment condition of 140°C for 15 minutes and further cooling to room temperature is designated as F2.

11. An easily dismantlable adhesive material according to any one of claims 1 to 10, The hardener comprises at least one of the following (b1) and (b2): (b1) A curing agent having a thermally dissociable structure, represented by the following general formula (b1-1): (b2) A curing agent having at least one selected from the group consisting of an amino group, a carboxyl group and a hydroxyl group as a group reactive with an epoxy group and not containing a thermally dissociable structure. 【Chemistry 3】 In general formula (b1-1), n is an integer of 2 or more, L represents a single bond or a divalent linking group; A represents an n-valent organic group containing a thermally dissociable structure, Z is at least one selected from the group consisting of an amino group, a hydroxy group, and a carboxy group; In general formula (b1-1), a plurality of Z's may be present, and the plurality of Z's may be the same or different.

12. An easily dismantlable adhesive material according to any one of claims 1 to 11, The easily dismantlable adhesive material is attached to the surface of an adherend, and a first heat treatment is performed to obtain a hardened body that bonds to the adherend, and then a second heat treatment is performed to expand the heat-expandable particles in the hardened body and dissociate the heat-dissociable structure of the heat-dissociable compound, and the hardened body is then cooled to room temperature and then dismantled from the adherend.

13. An article comprising an adherend and a cured product of the easily dismantlable adhesive material according to any one of claims 1 to 12 bonded to the adherend.

14. A dismantling method comprising: a dismantling step of heating the article according to claim 13 to dismantle the adherend and the cured body of the easily dismantlable adhesive material.

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