Easy-disassemblable resin composition, structure including cured product of easy-disassemblable resin composition, method for disassembling structure, and method for recycling material constituting structure

Abstract

To provide an easy-disassemblable resin composition that allows enhancement of resource recyclability through easy disassembly of a cured product.SOLUTION: The easy-disassemblable resin composition of the present invention contains a thermosetting resin and a thermally expandable filler having a core-shell structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an easily dismantlable resin composition, a structure comprising a cured product of the easily dismantlable resin composition, a method for dismantling a structure, and a method for recycling materials constituting the structure. [Background technology]

[0002] In recent years, the automotive industry has been actively promoting the electrification of vehicles in order to address global climate change and realize a carbon-neutral society. The neodymium magnets used in many of the motors of these electric vehicles contain rare elements known as rare earths, such as neodymium and dysprosium. However, there are concerns about the uneven distribution of rare earth resources and price fluctuations due to supply and demand imbalances, and the burden on the ecosystem caused by mining and refining them makes reducing their use a challenge. Therefore, the automotive industry is focusing on technology related to the reuse of rare earths as a way to make effective use of resources.

[0003] For example, it is known to remove, disassemble, and reuse magnets from motors that could not be installed in automobiles that did not meet shipping standards. Furthermore, for example, Patent Document 1 discloses a method in which the rotor is heated to the higher of the Curie temperature or the ashing temperature of the adhesive, and then vibrations are applied to the metal plate on the end face of the rotor such that the metal plate resonates, thereby removing the adhesive and the magnets from the holes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-216777 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional technology disclosed in Patent Document 1, the process of extracting rare earth elements from motor magnets requires manual disassembly and extraction of the magnets, leaving room for improvement in terms of simplifying the process and reducing recycling costs. Also, when attempting to dismantle motors and other components using chemicals, there are concerns about contamination by the chemicals.

[0006] As a result of intensive research conducted by the present inventors to solve this problem, they discovered that it is effective to use a thermally expandable filler with a core-shell structure when dismantling a cured resin composition used for fixing a rotor, etc. Furthermore, they found that controlling the adhesion of the resin composition to copper affects the dismantling properties of the cured resin composition, and devised a new index. [Means for solving the problem]

[0007] The present invention provides the following easily dismantlable resin composition, a structure including a cured product of the easily dismantlable resin composition, a method for dismantling a structure, and a method for recycling materials constituting the structure.

[0008] [1] An easily dismantlable resin composition containing a thermosetting resin and a thermally expandable filler having a core-shell structure. [2] An easily dismantlable resin composition containing a thermosetting resin, wherein the adhesion strength ratio (S2 / S1) measured by the following procedure a is 0.95 to 1.05, and the adhesion strength ratio (S3 / S1) is less than 0.020. [Step a] The easily dismantlable resin composition was molded onto a copper substrate under conditions of 175°C, 6.9 MPa, and 120 seconds, and then post-cured at 175°C for 4 hours to obtain a test piece a. Using test piece a, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300 μm / sec. The adhesion strength [N / mm 2 ] to S1 [N / mm 2 ]. In addition, after heating the test piece a at 180°C for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300µm / sec. The adhesion strength [N / mm 2 ] to S2 [N / mm 2 ]. In addition, after heating the test piece a at 300°C for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300µm / sec. The adhesion strength [N / mm 2 ] to S3 [N / mm 2 ]. [3] The easily dismantlable resin composition according to [1] or [2], The easily dismantlable resin composition, wherein the expansion starting temperature of the thermally expandable filler is equal to or higher than the molding temperature of the easily dismantlable resin composition. [4] The easily dismantlable resin composition according to any one of [1] to [3], The easily dismantlable resin composition, wherein the thermally expandable filler encapsulates a volatile substance or a low-boiling substance. [5] The easily dismantlable resin composition according to any one of [1] to [4], An easily dismantlable resin composition, wherein the content of the thermally expandable filler is 1 to 20% by mass based on the total amount of the easily dismantlable resin composition. [6] The easily dismantlable resin composition according to any one of [1] to [5], The easily dismantlable resin composition, wherein the thermosetting resin contains an epoxy resin. [7] The easily dismantlable resin composition according to any one of [1] to [6], An easily dismantlable resin composition further comprising a curing agent. [8] The easily dismantlable resin composition according to [7], The easily dismantlable resin composition, wherein the curing agent comprises a phenol-based curing agent. [9] The easily dismantlable resin composition according to any one of [1] to [8], An easily dismantlable resin composition in the form of powder, granules, or tablets.

[10] A cured product of the easily dismantlable resin composition according to any one of [1] to [9].

[11] In the cured product according to

[10] , The cured product contains a thermally expandable filler having a core-shell structure.

[12] A structure comprising a cured product of the easily dismantlable resin composition according to any one of [1] to [9].

[13] A method for dismantling a structure according to

[12] , A method for dismantling a structure, comprising the step of heating the structure to dismantle the cured product of the easily dismantlable resin composition.

[14] A method for recycling materials constituting the structure according to

[12] or

[13] , a step of heating the structure to dismantle the cured product of the easily dismantlable resin composition; and recovering said material from said structure. [Effects of the Invention]

[0009] According to the present invention, the cured product of the easily dismantled resin composition containing a thermosetting resin can be easily dismantled, thereby improving the recyclability of materials constituting a structure including the cured product of the easily dismantled resin composition. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view showing an example of a rotor. [Figure 2] FIG. 2 is a cross-sectional view showing the rotor shown in FIG. [Figure 3] 1 is a cross-sectional view showing an example of a motor in a direction perpendicular to a rotation axis direction. [Figure 4] FIG. 4 is a vertical cross-sectional view of the motor shown in FIG. 3 taken along the rotation axis. [Figure 5] FIG. 4 is an enlarged view of the periphery of a slot in the motor shown in FIG. 3. [Figure 6] FIG. 1 is a cross-sectional view showing an example of a power module. DETAILED DESCRIPTION OF THE INVENTION

[0011] In this specification, the notation "a to b" in the description of a range of values ​​means a to b, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass to 5% by mass." Furthermore, the lower and upper limits of a range of values ​​can be arbitrarily combined with the lower and upper limits of other ranges of values.

[0012] Unless otherwise specified, each of the components and materials exemplified in this specification may be used alone or in combination of two or more.

[0013] Hereinafter, embodiments of the present invention will be described in detail.

[0014] 1.Easily disassembled resin composition The easily dismantlable resin composition of the first embodiment contains a thermosetting resin and a thermally expandable filler (C) having a core-shell structure. As a result, when a cured product obtained by encapsulating other materials using the easily dismantlable resin composition of this embodiment is subsequently heated, the adhesion is reduced, and the cured product can be easily dismantled with a weak force. As a result, the load on the encapsulated materials is reduced, and the quality of the materials is maintained, thereby improving reusability.

[0015] Here, conventionally, a core-shell structured thermally expandable filler (C) is known as a filler that expands upon heating. In contrast, the present inventors have discovered that when a cured product of an easily dismantlable resin composition containing the core-shell structured thermally expandable filler (C) of this embodiment is heated, the cured product itself barely expands, its volume remains nearly constant, while the adhesion of the cured product decreases, resulting in easy dismantling. While the details of this are unclear, it is believed that the thermally expandable filler (C) contained in the resin composition of this embodiment does not expand due to heat during curing, maintaining the core-shell structure within the cured product, but then attempts to expand when heated to dismantle the cured product, thereby increasing the internal pressure of the cured product. As a result, it is presumed that the expansion pressure of the thermally expandable filler (C) dispersed within the cured product causes cracks to form around it, resulting in easy dismantling of the cured product.

[0016] In addition, as a second embodiment, an easily dismantlable resin composition containing a thermosetting resin has an adhesion strength ratio (S2 / S1) of 0.95 to 1.05 and an adhesion strength ratio (S3 / S1) of less than 0.020, as measured by the following procedure a. [Step a] The easily dismantlable resin composition was molded onto a copper substrate under conditions of 175°C, 6.9 MPa, and 120 seconds, and then post-cured at 175°C for 4 hours to obtain a test piece a. Using test piece a, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300 μm / sec. The adhesion strength [N / mm 2 ] to S1 [N / mm 2 ]. In addition, after heating the test piece a at 180°C for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300µm / sec. The adhesion strength [N / mm 2 ] to S2 [N / mm 2 ]. In addition, after heating the test piece a at 300°C for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300µm / sec. The adhesion strength [N / mm 2 ] to S3 [N / mm 2 ].

[0017] That is, as shown in step a, by controlling the adhesion between the cured product of the easily dismantlable resin composition and the copper substrate using the adhesion strength under specified temperature conditions as an index, a cured product with good adhesion can be obtained, while also obtaining good ease of dismantling of the cured product. Although the details of the reason for this are not clear, it is thought that by controlling the thermal behavior of the easily dismantlable resin composition containing a thermosetting resin, the balance between adhesion and ease of dismantling is improved.

[0018] The adhesion strength ratio (S2 / S1) measured by the procedure a is 0.95 to 1.05, preferably 0.96 to 1.03, and more preferably 0.97 to 1.02. The adhesion strength ratio (S3 / S1) measured by the procedure a is less than 0.020, preferably 0.010 or less, and more preferably 0.008 or less. Here, in step a, the adhesion strength S1 assumes the initial structure obtained using the easily dismantlable resin composition, the adhesion strength (S2) obtained by heating at 180°C for 30 minutes assumes the conditions under which the structure will be used, and the adhesion strength (S3) obtained by heating at 300°C for 30 minutes assumes the heat treatment when the structure is dismantled. Therefore, by setting the adhesion strength ratio (S2 / S1) within the above numerical range, good adhesion can be obtained during use of the structure obtained using the easily dismantlable resin composition. Also, by setting the adhesion strength ratio (S3 / S1) to the above upper limit or less, the adhesion of the structure obtained using the easily dismantlable resin composition can be reduced by heat treatment, thereby making it easy to dismantle.

[0019] The adhesive strength (S2) measured by procedure a is preferably 3.0 N / mm 2 in order to obtain good adhesiveness when the cured product is used. 2 More preferably, it is 4.0 N / mm 2 or more, and more preferably 5.0 N / mm 2 More preferably, 6.0 N / mm 2 That's all. The upper limit of the adhesion strength (S2) is not particularly limited.

[0020] The adhesive strength (S3) measured by procedure a is preferably 3.0 N / mm 2 More preferably, it is 2.0 N / mm 2 or less, and more preferably 1.0 N / mm 2 More preferably, it is 0.4 N / mm or less. 2 The following is the result. The lower limit of the adhesion strength (S3) is not particularly limited, and the specimen may already be peeled from the copper substrate before the adhesion strength is measured. In other words, the test piece is intended to peel from the copper substrate during heating at 300°C for 30 minutes. In this case, the adhesion strength (S3) is 0 N / mm 2 and the adhesion strength ratio (S3 / S1) is also 0.

[0021] The easily dismantlable resin compositions of the first embodiment and the second embodiment will be collectively described as this embodiment below.

[0022] The term "easily dismantlable" means that the cured product obtained by thermosetting the easily dismantlable resin composition of this embodiment can be easily or naturally crushed or separated without applying high stress to the cured product, for example, by heating the cured product to generate cracks. For example, easy dismantling is achieved by easily peeling the cured product of the easily dismantlable resin composition of this embodiment from the materials in the cured product (such as encapsulated materials).

[0023] The easily dismantlable resin composition satisfying each parameter obtained in the above step a can be realized by selecting the various components constituting the easily dismantlable resin composition and adjusting the contents thereof, etc. Specific examples include controlling the curability of the thermosetting resin (A) and the curing agent (B), selecting the thermally expandable filler (C), and adjusting the content thereof, etc.

[0024] Hereinafter, the components contained in the easily dismantlable resin composition (hereinafter also referred to as "resin composition") of this embodiment will be described.

[0025] [Thermosetting resin (A)] The resin composition of the present embodiment contains a thermosetting resin (A). Examples of the thermosetting resin (A) include one or more selected from phenolic resins, epoxy resins, phenoxy resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, melamine resins, silicone resins, cyanate resins, maleimide resins, cyanate resins, and acrylic resins. These thermosetting resins can be any monomer, oligomer, or polymer having two or more reactive functional groups in one molecule, and their molecular weights and molecular structures are not particularly limited.

[0026] The epoxy resin may be any monomer, oligomer, or polymer having two or more epoxy groups in one molecule, and the molecular weight and molecular structure thereof are not particularly limited. Specific examples of the epoxy resin include novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins and bisphenol F-type epoxy resins; aromatic glycidylamine-type epoxy resins such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, diaminodiphenylmethane-type glycidylamine, and aminophenol-type glycidylamine; hydroquinone-type epoxy resins; biphenyl-type epoxy resins; stilbene-type epoxy resins; triphenolmethane-type epoxy resins; triphenolpropane-type epoxy resins; and alkyl-modified triphenols.

[0033] Examples of the epoxy resin include one or more selected from the group consisting of phenol methane type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene-modified phenol type epoxy resins, naphthol type epoxy resins, naphthalene type epoxy resins, naphthylene ether type epoxy resins, aralkyl type epoxy resins such as phenol aralkyl type epoxy resins having a phenylene and / or biphenylene skeleton, and naphthol aralkyl type epoxy resins having a phenylene and / or biphenylene skeleton, and aliphatic epoxy resins such as vinylcyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diepoxy adipide. Among these, the thermosetting resin (A) is preferably an epoxy resin.

[0027] The content of the thermosetting resin (A) is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 30% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less, based on the total amount of the resin composition. By setting the content of the thermosetting resin (A) to the above lower limit or more, the flowability and moldability of the resin composition can be more effectively improved. On the other hand, by setting the content of the thermosetting resin (A) to the above upper limit or less, the curability can be improved and a good cured product can be obtained.

[0028] [Hardening agent (B)] The resin composition of this embodiment may contain a curing agent (B). The curing agent (B) is selected depending on the type of thermosetting resin (A) and is not particularly limited as long as it reacts with the thermosetting resin (A). Specific examples of the curing agent (B) include polyaddition-type curing agents, catalyst-type curing agents, and condensation-type curing agents.

[0029] Specific examples of the curing agent (B) include phenolic curing agents, amines, polyoxystyrenes such as polyparaoxystyrene, alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA), and acid anhydrides including aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA), polymercaptan compounds such as polysulfides, thioesters, and thioethers, isocyanate compounds such as isocyanate prepolymers and blocked isocyanates, and organic acids such as carboxylic acid-containing polyester resins.

[0030] Specific examples of the phenolic curing agent include one or more selected from novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, naphthol novolac resin, aminotriazine novolac resin, novolac resin, and trisphenylmethane-type phenol novolac resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; aralkyl-type resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; bisphenol compounds such as bisphenol A and bisphenol F; and resol-type phenolic resins. From the viewpoint of curability, the hydroxyl group equivalent of the phenolic resin-based curing agent is preferably, for example, 90 g / eq or more and 250 g / eq or less.

[0031] Specific examples of the amines include one or more selected from aliphatic polyamines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylenediamine (MXDA); aromatic polyamines such as diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diaminodiphenylsulfone (DDS); polyamine compounds including dicyandiamide (DICY) and organic acid dihydralazides; alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA); and acid anhydrides including aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA).

[0032] In this embodiment, when an epoxy resin is used as the thermosetting resin (A), it is preferable to combine it with a phenol-based curing agent as the curing agent (B).

[0033] The content of the curing agent (B) is preferably 5 to 30 parts by mass, more preferably 10 to 20 parts by mass, based on 100 parts by mass of the thermosetting resin (A).

[0034] The contents of the thermosetting resin (A) and the curing agent (B) are appropriately set depending on the thermosetting resin (A) and the curing agent (B). For example, the phenolic curing agent as the curing agent (B) and the epoxy resin as the thermosetting resin (A) are adjusted so that the equivalent ratio (EP) / (OH) of the number of epoxy groups (EP) in the total thermosetting resin to the number of phenolic hydroxyl groups (OH) in the total phenolic resin is preferably 0.8 or more and 1.6 or less, more preferably 0.9 or more and 1.3 or less, and even more preferably 1.0 or more and 1.2 or less. When the equivalent ratio is within the above range, the curing characteristics of the resulting resin composition of this embodiment can be improved.

[0035] [Thermal expansion filler (C)] The thermally expandable filler (C) is a substance containing a volatile expanding agent inside the shell of a core-shell structure. The volatile expanding agent is a substance that generates gas at temperatures below the softening point of the shell. When the thermally expandable filler (C) is heated, the volatile expanding agent becomes gaseous and escapes to the outside (wetting and spreading), while the shell softens (or melts). In this embodiment, the volatile expansion agent and shell component of the thermally expandable filler (C) attempt to expand within the cured product, increasing the internal pressure, reducing adhesion around the thermally expandable filler (C), causing cracks to form within the cured product, and resulting in easy disassembly.

[0036] The thermally expandable filler (C) preferably has an average particle size (D50) measured with a laser diffraction particle size distribution analyzer of 1 μm or more and 200 μm or less, more preferably 3 μm or more and 100 μm or less, and even more preferably 5 μm or more and 50 μm or less. When the average particle size (D50) of the thermally expandable filler (C) is within the above range, the resin composition can have good moldability.

[0037] The expansion starting temperature of the thermally expandable filler (C) is preferably equal to or higher than the molding temperature of the resin composition, specifically, preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher. That is, since the expansion starting temperature of the thermally expandable filler (C) is equal to or higher than the molding temperature of the resin composition, the thermally expandable filler (C) can exist without expanding in a molded product (cured product) obtained using the resin composition. As a result, when the molded product (cured product) is subsequently heated, the thermally expandable filler (C) can be expanded, and the cured product can be easily disassembled. On the other hand, the expansion starting temperature of the thermally expandable filler (C) is preferably 800°C or lower, more preferably 700°C or lower, and even more preferably 600°C or lower, in order to reduce the thermal load when the cured product is disassembled.

[0038] The maximum expansion temperature of the thermally expandable filler (C) is preferably equal to or higher than the molding temperature of the resin composition, specifically, preferably 165°C to 500°C, more preferably 180°C to 450°C, and even more preferably 200°C to 300°C. By setting the maximum expansion temperature of the thermally expandable filler (C) to the above lower limit or higher, the molded product (cured product) tends to be easily dismantled. On the other hand, by setting the maximum expansion temperature of the thermally expandable filler (C) to the above upper limit or lower, the thermal load during dismantling of the cured product can be reduced.

[0039] The expansion start temperature and maximum expansion temperature of the thermally expandable filler (C) can be measured, for example, using DMA as follows. Specifically, 0.5 mg of the thermally expandable filler (C) is placed in an aluminum cup with a diameter of 6.0 mm and a depth of 4.8 mm, an aluminum lid is placed on top of the thermally expandable filler (C), and the sample height is measured while a force of 0.01 N is applied from above using a pressure probe. In this state, the sample is heated from 20°C to 300°C at a heating rate of 10°C / min, and the displacement of the pressure probe in the vertical direction is measured. The temperature at which displacement in the positive direction begins can be regarded as the expansion start temperature (°C) of the thermally expandable filler (C), and the temperature at which the maximum displacement is shown can be regarded as the maximum expansion temperature (°C) of the thermally expandable filler (C). In the resin composition according to this embodiment, by setting the expansion start temperature and maximum expansion temperature of the thermally expandable filler (C) within the above-mentioned ranges, a good cured product can be obtained when used, and the cured product can be easily disassembled.

[0040] The maximum expansion ratio of the thermally expandable filler (C) is preferably 3 times or more, more preferably 10 times or more, even more preferably 20 times or more, particularly preferably 30 times or more, and even more preferably 50 times or more. The maximum expansion ratio indicates the maximum increase in the volume of the particle group compared to the volume before thermal expansion when the particle group of the thermally expandable filler (C) in an unexpanded state is heated and expanded and the volume of the particle group is measured. By setting the maximum expansion ratio of the thermally expandable filler (C) to the above-mentioned range, the adhesiveness of the cured product can be further reduced.

[0041] [Volatile leavening agent] In the thermally expandable filler (C) according to this embodiment, the volatile expanding agent is, for example, a linear hydrocarbon such as ethane, ethylene, propane, propene, butane, isobutane, butene, isobutene, pentane, isopentane, neopentane, hexane, heptane, octane, nonane, decane, dodecane, undecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, or nonadecane; Branched hydrocarbons such as isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, isododecane, 3-methylundecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, isohexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isononadecane, and 2,6,10,14-tetramethylpentadecane Examples of volatile expanding agents include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cyclododecane, cyclotridecane, hexylcyclohexane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, and octadecylcyclohexane; petroleum ether; halides thereof; chlorofluorocarbons such as CClF, CClF, CClF, and CClF-CClF; fluorine-containing compounds such as hydrofluoroethers; tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane; and compounds that thermally decompose to produce gas upon heating. These volatile expanding agents may be used alone or in combination of two or more. Furthermore, it is preferable that the volatile expanding agent contains a hydrocarbon.

[0042] Among these, the volatile expanding agent preferably includes at least one selected from propane, butane, pentane, hexane, heptane, isobutane, isopentane, isohexane, isoheptane, isooctane, cyclopentane, cyclohexane, and petroleum ether, and more preferably includes isobutane.

[0043] The volatile expanding agent preferably contains a hydrocarbon having a boiling point of -30° C. or higher and 175° C. or lower, and more preferably contains a hydrocarbon having a boiling point of -20° C. or higher and 150° C. When the boiling point of the volatile expanding agent is within the above range, the heating temperature of the cured product can be adjusted, reducing the load on the material.

[0044] [shell] In the thermally expandable filler (C), the shell in the core-shell structure preferably contains a thermoplastic resin. When the shell contains a thermoplastic resin, the thermally expandable filler (C) can soften (melt) when the cured product is heated, thereby reducing the adhesion of the cured product.

[0045] The thermoplastic resin is preferably a polymer having at least one structural unit selected from the group consisting of structural units derived from vinylidene chloride, structural units derived from nitrile monomers, structural units derived from (meth)acrylic acid ester monomers, structural units derived from monomers having an amide group, polymethacrylimide structural units having a nitrile group and a carboxyl group, in which at least a portion of these functional groups are cyclized by heating or the like, and structural units derived from monomers having a glycidyl group in the molecule. Examples of the monomer include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and dicyclopentenyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and isobornyl methacrylate; acrylonitrile, methacrylonitrile, vinylidene chloride, vinyl chloride, styrene, acrylic acid, methacrylic acid, vinyl acetate, α-methylstyrene, chloroprene, neoprene, and butadiene. When the thermoplastic resin contains the polymer of the above embodiment, the shell of the thermally expandable filler (C) can obtain good heat resistance and gas barrier properties in the resin composition, and can also obtain flexibility and elasticity.

[0046] From the viewpoint of selecting a thermoplastic resin having low reactivity with the epoxy resin contained in the resin composition of this embodiment, it is more preferable that the thermoplastic resin contains a structural unit derived from vinylidene chloride and a structural unit derived from a (meth)acrylic acid ester monomer. Polymerization These polymerizable monomers can be used alone or in combination of two or more. The vinylidene chloride (co)polymer may be a (co)polymer obtained using vinylidene chloride alone or a mixture of vinylidene chloride and a vinyl monomer copolymerizable therewith as the polymerizable monomer. Examples of the monomer copolymerizable with vinylidene chloride include acrylonitrile, methacrylonitrile, methacrylic acid esters, acrylic acid esters, styrene, acrylic acid, methacrylic acid, and vinyl acetate. The (meth)acrylonitrile (co)polymer may be a (co)polymer obtained using (meth)acrylonitrile alone or a (co)polymer obtained using (meth)acrylonitrile and a vinyl monomer copolymerizable therewith as the polymerizable monomer. Examples of the vinyl monomer copolymerizable with (meth)acrylonitrile include vinylidene chloride, acrylic acid esters, methacrylic acid esters, styrene, acrylic acid, methacrylic acid, and vinyl acetate. This allows for solvent resistance and foamability at high temperatures to be achieved.

[0047] Examples of commercially available products of the thermally expandable filler (C) include Matsumoto Microsphere (registered trademark) manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., Advancel manufactured by Sekisui Chemical Co., Ltd., Kureha Microsphere (manufactured by Kureha Chemical Industry Co., Ltd.), Dieform manufactured by Dainichiseika Color & Chemicals Co., Ltd., Expancel (registered trademark) manufactured by Axon Nobel, Styrodia manufactured by JSP, Heat Pole manufactured by JSP, Clear Pole manufactured by JSP, and Kanepearl manufactured by Kaneka Corporation.

[0048] The content of the thermally expandable filler (C) is, for example, preferably 0.1 mass% or more and 40 mass% or less, more preferably 1 mass% or more and 30 mass% or less, and even more preferably 2 mass% or more and 20 mass% or less, relative to 100 mass% of the total solid content of the resin composition. By adjusting the content of the thermally expandable filler (C) to the above lower limit or more, it is possible to improve the ease of dismantling of the cured product while maintaining good moldability of the resin composition. By setting the content of the thermally expandable filler (C) to the above upper limit or less, it becomes possible to obtain good dismantling properties of the cured product and also to improve the moldability of the resin composition.

[0049] [Inorganic filler (D)] The resin composition of the present embodiment may contain an inorganic filler (D) other than the thermally expandable filler (C).

[0050] The inorganic filler (D) is used to increase the mechanical strength and to impart heat resistance, flame retardancy, etc. depending on the intended use of the cured product.

[0051] Specific examples of the inorganic filler (D) include silicates such as talc, calcined clay, uncalcined clay, mica, and glass; oxides such as fused silica, spherical silica, crushed silica, titanium oxide, and boehmite; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates or sulfites such as barium sulfate, calcium sulfate, and calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; nitrides such as aluminum nitride, boron nitride, silicon nitride, and carbon nitride; and titanates such as strontium titanate and barium titanate. These may be used alone or in combination of two or more.

[0052] The average particle size D50 of the inorganic filler (D) is preferably 0.01 μm or more and 75 μm or less, more preferably 0.5 μm or more and 40 μm or less, and even more preferably 1 μm or more and 30 μm or less. By setting the average particle size of the inorganic filler within the above range, the filling property is improved. The average particle size D50 can be the average particle size converted into volume (cumulative 50%) using a commercially available laser particle size distribution analyzer.

[0053] The content of the inorganic filler (D) is appropriately set depending on the application, but is preferably 20 to 85 mass % relative to the total amount of the resin composition, more preferably 40 to 75 mass %, and even more preferably 50 to 70 mass %. By adjusting the content of the inorganic filler (D) to the above lower limit or more, the shelf life and curability of the cured product can be improved. On the other hand, by adjusting the content of the inorganic filler (D) to the above upper limit or less, the resin composition can have good flowability and can effectively improve moldability.

[0054] [Coupling agent] When the resin composition of this embodiment contains the thermally expandable inorganic filler (C) or the inorganic filler (D), it may contain a coupling agent, which can suppress aggregation of the thermally expandable inorganic filler (C) and the inorganic filler (D) and provide good fluidity.

[0055] As the coupling agent, known coupling agents such as various silane-based compounds such as epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, and vinylsilane, titanium-based compounds, aluminum chelates, and aluminum / zirconium-based compounds can be used.

[0056] More specifically, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-anilinopropyltrimethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-[bis(β-hydroxyethyl)]aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl) silane coupling agents such as -γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-(β-aminoethyl)aminopropyldimethoxymethylsilane, N-(trimethoxysilylpropyl)ethylenediamine, N-(dimethoxymethylsilylisopropyl)ethylenediamine, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilane, vinyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine hydrolysate;Examples of titanate-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl - aminoethyl) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridodecyl benzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, and tetraisopropyl bis (dioctyl phosphite) titanate. These may be used alone or in combination of two or more.

[0057] The content of the coupling agent is not particularly limited, but is preferably 0.05% by mass or more and 3% by mass or less, and more preferably 0.1% by mass or more and 2% by mass or less, based on the entire resin composition. By adjusting the content of the coupling agent to the above lower limit or more, the dispersibility of the inorganic filler (D) in the resin composition can be improved. By adjusting the content of the coupling agent to the above upper limit or less, the flowability of the resin composition can be improved, and moldability can be improved.

[0058] [Curing accelerator] The resin composition of the present embodiment may contain a curing accelerator. The curing accelerator typically accelerates the reaction between the thermosetting resin (A) and the curing agent (B).

[0059] Specific examples of the curing accelerator include phosphorus atom-containing compounds such as organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, or adducts of phosphonium compounds and silane compounds; amidine compounds such as 1,8-diazabicyclo(5,4,0)undecene-7 and imidazole; nitrogen atom-containing compounds such as tertiary amines such as benzyldimethylamine, amidinium salts, or ammonium salts; and phenolic compounds such as phenol, bisphenol A, nonylphenol, and 2,3-dihydroxynaphthalene. Examples of the organic phosphines include triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine triphenylborane, 1,2-bis-(diphenylphosphino)ethane, etc. These may be used alone or in combination of two or more.

[0060] The content of the curing accelerator is appropriately set depending on the application, but is preferably 0.1 to 1 mass %, and more preferably 0.2 to 5 mass %, based on the total amount of the resin composition. By setting the content of the curing accelerator to be equal to or greater than the above lower limit, the resin composition can be appropriately cured. On the other hand, by setting the content of the curing accelerator to be equal to or less than the above upper limit, the molten state can be prolonged, and the low-viscosity state can be prolonged.

[0061] [Hydroxyl group-containing cyclic compound] When the resin composition of this embodiment contains a curing accelerator, it may contain a compound in which a hydroxyl group is bonded to each of two or more adjacent carbon atoms constituting an aromatic ring (hereinafter also referred to as a "hydroxyl group-containing cyclic compound"). This makes it possible to suppress reactions during melt-kneading of the resin composition, even when a phosphorus atom-containing curing accelerator without latency is used as the curing accelerator, and a stable resin composition can be obtained. Furthermore, the hydroxyl group-containing cyclic compound also has the effect of reducing the melt viscosity of the resin composition and improving its flowability.

[0062] The hydroxyl group-containing cyclic compound may be a monocyclic compound represented by the following general formula (5) or a polycyclic compound represented by the following general formula (6). These compounds may have a substituent other than a hydroxyl group.

[0063] [ka]

[0064] In general formula (5), one of R15 and R19 is a hydroxyl group, and the other is a hydrogen atom, a hydroxyl group, or a substituent other than a hydroxyl group. R16, R17, and R18 are each a hydrogen atom, a hydroxyl group, or a substituent other than a hydroxyl group.

[0065] [ka]

[0066] In general formula (6), one of R20 and R26 is a hydroxyl group, and the other is a hydrogen atom, a hydroxyl group, or a substituent other than a hydroxyl group. R21, R22, R23, R24, and R25 are hydrogen atoms, a hydroxyl group, or a substituent other than a hydroxyl group.

[0067] Specific examples of the monocyclic compound represented by the general formula (5) include catechol, pyrogallol, gallic acid, gallic acid esters, and derivatives thereof. Specific examples of polycyclic compounds represented by general formula (6) include 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, and derivatives thereof. Among these, compounds in which a hydroxyl group is bonded to each of two adjacent carbon atoms constituting an aromatic ring are preferred because of the ease of controlling fluidity and curability. Furthermore, when considering volatilization during the kneading process, it is more preferable to use a compound in which the mother nucleus is a naphthalene ring, which has low volatility and high weighing stability. In this case, the hydroxyl group-containing cyclic compound can be, specifically, a compound having a naphthalene ring, such as 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, and derivatives thereof. These hydroxyl group-containing cyclic compounds may be used alone or in combination of two or more.

[0068] The content of the hydroxyl group-containing cyclic compound is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more, relative to 100% by mass of the total resin composition. When the content of the hydroxyl group-containing cyclic compound is within the above range, the resin composition can be sufficiently reduced in viscosity and has improved flowability. Furthermore, the content of the hydroxyl group-containing cyclic compound is preferably 2% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.5% by mass or less, relative to 100% by mass of the total resin composition. When the content of the hydroxyl group-containing cyclic compound is within the above range, there is little risk of a decrease in the curability of the resin composition or a decrease in the physical properties of the cured product.

[0069] Furthermore, the resin composition of the present embodiment may further contain various additives, such as flame retardants; colorants such as carbon black; release agents such as natural waxes, synthetic waxes, higher fatty acids or metal salts thereof, paraffin, and polyethylene oxide; stress reducing agents such as silicone oil and silicone rubber; ion scavengers such as hydrotalcites or hydrous oxides of elements selected from magnesium, aluminum, bismuth, titanium, and zirconium; adhesion promoters such as thiazoline, diazole, triazole, triazine, and pyrimidine; and antioxidants.

[0070] The flame retardant may be an inorganic flame retardant. Specific examples of inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, zinc borate, zinc molybdate, phosphazene, and carbon black. One or more of the above specific examples can be blended as the flame retardant. Among these, aluminum hydroxide is preferred from the viewpoint of achieving flame retardancy and easy dismantling.

[0071] Furthermore, aluminum hydroxide decomposes when exposed to high temperatures, and therefore, when a structure using the resin composition of the present embodiment containing aluminum hydroxide is heated to 200°C or higher, the structure can be destroyed from the inside by the dehydration of the aluminum hydroxide, and the structure can be easily disassembled.

[0072] The lower limit of the aluminum hydroxide content is preferably 1% by mass or more relative to the total amount of the resin composition in order to obtain flame retardancy, and is preferably 10% by mass or more, and more preferably 12% by mass or more, in order to obtain not only flame retardancy but also easy dismantling properties. On the other hand, the upper limit of the aluminum hydroxide content can be appropriately set depending on the application of the resin composition, and may be, for example, 60 mass % or less.

[0073] In order to obtain the easy dismantling property due to the aluminum hydroxide while maintaining good moldability of the resin composition, the total content of the thermally expandable inorganic filler (C), the inorganic filler (D), and the aluminum hydroxide is preferably 50 to 90 mass%, more preferably 55 to 80 mass%, and even more preferably 60 to 70 mass%, relative to the total amount of the resin composition, in order to maintain good moldability.

[0074] [Method of producing resin composition] Next, a method for producing the resin composition of this embodiment will be described. The method for producing the resin composition of this embodiment is not particularly limited, but may involve, for example, mixing the thermosetting component and any other optional components using a mixer or the like, followed by melt-heating and kneading at approximately 90 to 120°C using a heated kneader, heated roll, extruder, or the like. The resulting kneaded mixture is then cooled and pulverized to obtain a powdery or granular resin composition. If necessary, the resin composition may be compressed into tablets after pulverization, or may be formed into a sheet by, for example, vacuum lamination or compression molding after pulverization.

[0075] Alternatively, for example, the thermosetting component and other optional components may be dissolved, mixed, and stirred in a solvent using various mixers such as those employed in ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill dispersion, high-speed shear dispersion, or rotation-revolution dispersion, to prepare a varnish-like resin composition. Specific examples of the solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, heptane, cyclohexane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, cellosolve-based solvents, carbitol-based solvents, anisole, and N-methylpyrrolidone. The solvents may be used alone or in combination of two or more.

[0076] 2.Cured product / structure The cured product of this embodiment is obtained by curing the above-mentioned easily dismantlable resin composition, and contains a thermally expandable filler (C) having a core-shell structure dispersed in a thermosetting resin. That is, the thermally expandable filler (C) maintains its core-shell structure in the cured product. In other words, the easily dismantlable resin composition does not substantially expand during the molding process (curing process) of the easily dismantlable resin composition. As a result, by heating the cured product, the volatile expansion agent and shell component of the thermally expandable filler (C) can be expanded, resulting in an increase in the internal pressure of the cured product, a decrease in adhesion around the thermally expandable filler (C), and the occurrence of cracks within the cured product, making the cured product easily dismantlable. The phrase "not substantially expanded" means that the core-shell structure is not deformed by the expansion of the thermally expandable filler (C).

[0077] The presence of the thermally expandable filler (C) with a core-shell structure in the cured product can be confirmed by observing the cross section of the cured product with a scanning electron microscope (SEM).

[0078] The structure of this embodiment includes a cured product of the easily dismantlable resin composition. The cured product can be obtained by thermally curing the resin composition of this embodiment at 100 to 200°C for 10 to 900 seconds.

[0079] The structure can be widely applied to, for example, composite materials for transportation equipment such as automobiles, trains, ships, and aircraft; semiconductor devices equipped with semiconductor chips, semiconductor elements, and printed wiring boards; composite materials for factory equipment such as work robots; electronic devices such as electric circuit display devices, information and communication terminals, light-emitting diodes, physical batteries, and chemical batteries; composite materials for civil engineering and construction; and composite materials for sports and recreation. Among these, composite materials for transportation equipment such as automobiles and semiconductor devices are preferred due to the importance of addressing environmental issues. Specific examples of semiconductor devices include those comprising a semiconductor element and an encapsulant that encapsulates the semiconductor element, the encapsulant being made of a cured product of the resin composition of this embodiment. The encapsulation method is not particularly limited, and known methods can be used. In particular, it is preferable to apply the present invention to rotors, stators, and power modules, the details of which will be described later.

[0080] <Rotor> The rotor of this embodiment comprises a cured product of the easily dismantlable resin composition described above. The cured product can be obtained by thermally curing the resin composition of this embodiment at 100 to 200°C for 10 to 900 seconds.

[0081] An example of the rotor of this embodiment will be described below. Fig. 1 is a plan view showing a rotor 100 according to this embodiment. Fig. 2 is a cross-sectional view showing the rotor 100 shown in Fig. 1. Note that Figs. 1 and 2 are schematic views showing the rotor 100, and the configuration of the rotor 100 according to this embodiment is not limited to that shown in Figs. 1 and 2.

[0082] The rotor 100 includes a rotor core 110, a magnet 120, and a fixing member 130. A hole 150 is formed in the rotor core 110. The magnet 120 is inserted into the hole 150. The fixing member 130 is provided in a space 140 between the hole 150 and the magnet 120. The fixing member 130 is formed using the above-mentioned easily dismantlable resin composition.

[0083] The rotor 100 according to this embodiment constitutes a motor to be mounted on, for example, an automobile, etc. The motor includes the rotor 100 and a stator provided around the rotor 100. The stator is composed of a stator core and a coil wound around the stator core. 2, the rotor 100 is attached to a rotating shaft 170. The rotation generated by the rotor 100 is transmitted to the outside via the rotating shaft 170.

[0084] The rotor core 110 has a through hole for inserting the rotary shaft 170. The rotor core 110 is fixed to the rotary shaft 170 inserted into the through hole. The shape of the rotor core 110 is not particularly limited, but may be, for example, a circle or a polygon when viewed from above. 2, rotor core 110 is formed by laminating a plurality of thin magnetic steel sheets 112. Electromagnetic steel sheets 112 are made of, for example, iron or an iron alloy.

[0085] 2, end plates 118a and 118b are provided at both axial ends of rotor core 110. That is, end plate 118a is provided on top of stacked electromagnetic steel sheets 112. End plate 118b is provided below stacked electromagnetic steel sheets 112. End plate 118a and end plate 118b are fixed to rotating shaft 170 by, for example, welding.

[0086] 1, a plurality of holes 150 are provided in the rotor core 110. The plurality of holes 150 are arranged in the rotor core 110 so as to be point-symmetric with respect to the axis of the rotary shaft 170. As shown in FIG. 1, in the rotor 100 of this embodiment, a plurality of hole groups, each consisting of, for example, two adjacent hole groups 150, are arranged along the periphery of the rotating shaft 170. The plurality of hole groups are arranged, for example, so as to be spaced apart from one another. The two holes 150 that make up one hole group are arranged, for example, in a V-shape in plan view. In this case, the two holes 150 that make up one hole group are arranged, for example, so that their opposing ends are located on the rotating shaft 170 side. Furthermore, the two holes 150 that make up one hole group are arranged, for example, so as to be spaced apart from one another.

[0087] <Stator> The stator of this embodiment includes a cured product of the easily dismantlable resin composition described above. The cured product is obtained by thermally curing the resin composition of this embodiment at 100 to 200°C for 10 to 900 seconds.

[0088] Fig. 3 is a schematic cross-sectional view perpendicular to the rotational axis direction of motor 101. Fig. 4 is a schematic cross-sectional view of motor 101 in the rotational axis direction. Fig. 5 is an enlarged view of the periphery of the slot (area X in Fig. 3), and is a schematic cross-sectional view of the portion where coil 9 protrudes from the end of slot 8.

[0089] The motor 101 includes a case 1, and a rotor 2, a stator 4, and a coil 9 housed inside the case 1.

[0090] The case 1 is configured to have a cylindrical portion 1a and side plate portions 1b, 1c that close both axial ends of the cylindrical portion 1a. The case 1 can be made of a material such as an aluminum alloy (cast metal product), a resin material, or a combination thereof.

[0091] As shown in Fig. 3, the rotor 2 is housed inside the case 1. As shown in Fig. 4, a rotary shaft 3 is attached to the center of the rotor 2 as an output shaft. Both ends of the rotary shaft 3 are supported by the side plate portions 1b and 1c via bearings 3a. This allows the rotor 2 to rotate freely around the rotary shaft 3.

[0092] Permanent magnets 5 are installed inside the rotor 2. Specifically, as shown in Fig. 3, multiple (eight in this example) permanent magnets 5 are arranged at equal intervals on the same circumference. At this time, the magnetic poles of adjacent permanent magnets 5 are set to be different from each other.

[0093] 4, a cylindrical stator 4 is disposed and fixed on the inner periphery of the cylindrical portion 1a so as to surround the outer periphery of the rotor 2. A minute gap (air gap) is provided between the inner periphery of the stator 4 and the outer periphery of the rotor 2.

[0094] Stator core 41 is formed by stacking multiple electromagnetic steel sheets in the axial direction and closely fixing them together. When viewed from the axial end as shown in FIG. 3, it has a ring-shaped yoke portion 6 and multiple teeth portions 7 extending from yoke portion 6 toward rotor 2 (the inner periphery). The multiple teeth portions 7 are arranged at equal intervals in the circumferential direction. In this example, as shown in FIG. 3, 24 teeth portions 7 are provided. Slots 8 are provided between each tooth portion 7. The teeth portions 7 are also provided with a thin resin layer 50 formed by wrapping a resin composition around them to cover them.

[0095] The coil 9 is a U-shaped rectangular wire wound so as to straddle the tooth portion 7 and be housed in two spaced-apart slots 8. Here, the coil 9 is housed in a distributed winding in a liner member 20 arranged in the slot 8 (FIG. 3). The coil 9 has a first coil end and a second coil end. The first coil end protrudes to one axial side of the stator core 41. The second coil end protrudes to the other axial side of the stator core 41. In other words, the coil 9 has a pair of coil ends that protrude from both axial sides of the stator core 41. The coil 9 is formed using a conductive wire made of a conductor such as copper, aluminum, or iron.

[0096] The teeth 7 are provided to correspond to the permanent magnets 5 of the rotor 2 described above, and by sequentially exciting each coil 9, the rotor 2 rotates due to attraction and repulsion with the corresponding permanent magnets 5.

[0097] The teeth 7 are tapered, with a larger circumferential width on the outer periphery and a smaller width on the inner periphery. Teeth tips 71 are formed at the inner periphery end of the teeth 7, facing each other in the circumferential direction so as to reduce the width of the slots 8.

[0098] The slots 8 are spaces between adjacent teeth 7, and as shown in Fig. 5, are arranged so that wall surfaces 72 of teeth 7 that face each other in the radial direction are parallel to each other. The space between the tooth tips 71 forms the inner peripheral opening of the slots 8. The slots 8 are provided with multiple coils 9 arranged on the outer peripheral side (the yoke portion 6 side) and a resin sealing portion 65 arranged on the inner peripheral side (the tooth tip 71 side).

[0099] 5, the resin sealing portion 65 is provided on the inner circumferential side (tooth tip end 71 side) of the slot 8. The resin sealing portion 65 may be provided by insert molding, or may be provided as a separate component. The resin material used for the resin sealing portion 65 is the above-mentioned easily dismantlable resin composition.

[0100] In one embodiment, the resin encapsulation portion 65 is provided so as to cover the coil 9 only within the slot 8 . In another embodiment, the resin sealing portion 65 is provided to cover the coil 9 in the slot 8 and also to cover one of the pair of coil ends, in other words, to cover only one of the first and second coil ends. In yet another embodiment, the resin sealing portion 65 is provided so as to cover the coil 9 in the slot 8 and also to cover both of the pair of coil ends, in other words, to cover both the first and second coil ends.

[0101] <Power module> Fig. 6 is a cross-sectional view showing the configuration of a power module (semiconductor device) 100 according to this embodiment. The power module 100 shown in Fig. 6 includes a semiconductor element 21 mounted on a substrate 30, and a sealing material 51 that seals the semiconductor element 21.

[0102] A lead frame is used as the substrate 30. The lead frame is made of metal, for example, copper.

[0103] The semiconductor element 21 is a power semiconductor element, and preferably a power semiconductor element that satisfies any one of the following conditions (a) to (d). (a) Semiconductor devices with a power consumption of 2.0 W or more (b) a semiconductor element made of one or more semiconductors selected from the group consisting of SiC, GaN, Ga2O3, and diamond; (c) Semiconductor element with a voltage of 1.0 V or more (d) Power density is 10 W / cm 3 The above semiconductor elements

[0104] The power consumption of semiconductor element 21 is, for example, 2.0 W or more, as specified in the above condition (a), preferably 3.0 W or more, and may be, for example, 4.0 W or less. The voltage of semiconductor element 21 is, for example, 1.0 V or more, which satisfies the above-mentioned condition (c), and is preferably 3.0 V or more, and may be, for example, 5.0 V or more. The voltage of semiconductor element 21 may also be, for example, 100 V or less. The power density of the semiconductor element 21 is, for example, 10 W / cm 2 under the above-mentioned condition (d). 3 More than 20 W / cm 3 or more, and for example, 30 W / cm 3 The power density of the semiconductor element 21 may be, for example, 200 W / cm 3 It may be the following: Furthermore, the semiconductor element 21 can operate in a high temperature environment of, for example, 200° C. or higher, preferably 260° C. or higher.

[0105] The semiconductor element 21 is preferably a power semiconductor element provided on the substrate 30, and includes one or more electronic components selected from the group consisting of a rectifier diode, a power transistor, a power MOSFET, an insulated gate bipolar transistor (IGBT), a thyristor, a gate turn-off thyristor (GTO), and a triac.

[0106] The semiconductor element 21 is mounted on, for example, a die pad 32 of a substrate 30 and is electrically connected to outer leads 34 via wires 40 .

[0107] The encapsulant 51 encapsulates the semiconductor element 21 so as to cover the other surface of the semiconductor element 21 opposite to the surface facing the substrate 30. The encapsulant 51 of this embodiment is made of a cured product of the above-mentioned easily dismantlable resin composition. The encapsulant 51 can be formed, for example, by encapsulating the easily dismantlable resin composition using a known method such as transfer molding or compression molding.

[0108] 3.Disassembly method The method for dismantling a structure of the present embodiment includes a step of heating the structure to dismantle the cured product of the easily dismantlable resin composition. The cured material can be disassembled by heating, eliminating the need for mechanical tools to destroy the cured material. In addition, the expansion of the cured material due to heating is suppressed, reducing the load on the material due to internal stress.

[0109] The heating temperature can be set appropriately depending on the type of thermally expandable inorganic filler (C), etc., but from the viewpoint of improving ease of dismantling, it is preferably set to the expansion start temperature of the thermally expandable inorganic filler (C) or higher, specifically, preferably 250°C or higher, more preferably 300°C or higher, and the temperature may be further increased depending on the use of the structure or from the viewpoint of shortening the time until dismantling. Specifically, if the structure is a rotor, the temperature may be set to 350°C or higher to accommodate demagnetization of the magnet. On the other hand, the heating temperature is preferably 600°C or lower, more preferably 500°C or lower, from the viewpoint of reducing the thermal load on the structure and the environmental load.

[0110] The heating method is not particularly limited, and any known method can be used.

[0111] 4.Recycling methods The recycling of this embodiment is a method for recycling materials that constitute the above-mentioned structure, and includes a step of heating the structure to dismantle the cured product of the easily dismantlable resin composition, and a step of recovering the materials from the structure. This allows the materials used in the structure to be reused. The process of dismantling the hardened product is the same as the method described above in the dismantling method.

[0112] Furthermore, the method for recovering materials from a structure is not particularly limited as long as it does not degrade the quality of the material. For example, a method may be used in which the structure is destroyed together with the hardened material that has become brittle due to dismantling, and the material is recovered.

[0113] When the structure is a rotor, the material recovered from the rotor is not particularly limited as long as it is heat-resistant, and examples thereof include metals (electromagnetic steel sheets) and permanent magnets.

[0114] When the structure is a stator, the material recovered from the stator is not particularly limited as long as it is heat-resistant, and examples thereof include coils and metals (electromagnetic steel sheets).

[0115] When the structure is a power module, the material recovered from the power module is not particularly limited as long as it is heat-resistant, and examples thereof include metallic lead frames.

[0116] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted. [Example]

[0117] Next, the present invention will be described in detail with reference to examples, but the content of the present invention is not limited to the examples.

[0118] <Preparation of Resin Composition> The raw materials shown below were mixed at the solid content ratios shown in Table 1 to obtain mixtures. Mixing was carried out at room temperature using a Henschel mixer. The resulting mixture was then roll-kneaded at 90 to 120°C to obtain a kneaded product. The resulting kneaded product was cooled and then pulverized to obtain each resin composition.

[0119] [Raw materials] (Epoxy resin (A)) Epoxy resin: Orthocresol novolac epoxy resin (Nippon Kayaku Co., Ltd., EOCN-1020-55) (Hardening agent (B)) Hardener: Novolac phenolic resin (Sumitomo Bakelite Co., Ltd., PR-HF-3) (Thermal expansion filler (C)) Thermally expandable filler 1: Matsumoto Microspheres, "FN-105D" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd. (average particle size 35-45 μm, expansion start temperature 120-135°C, maximum expansion temperature 175-185°C) Thermally expandable filler 2: Matsumoto Microsphere, Matsumoto Yushi Pharmaceutical Co., Ltd. "FN-190SSD" (average particle size 10-15 μm, expansion start temperature 155-165°C, maximum expansion temperature 210-220°C) Thermally expandable filler 3: Matsumoto Microsphere, Matsumoto Yushi Pharmaceutical Co., Ltd. "F-260D" (average particle size 20-35 μm, expansion start temperature 190-200°C, maximum expansion temperature 250-260°C) (Inorganic filler (D)) Inorganic filler 1: Fused crushed silica (FMT-05, manufactured by Fumitec Co., Ltd.) (average particle size 4.7 μm) Inorganic filler 2: Fused spherical silica (manufactured by Denka Co., Ltd., FB-560) (average particle size 31 μm) Inorganic filler 3: Fused spherical silica (manufactured by Denka Co., Ltd., FB-105) (average particle size 10.6 μm) (others) Silane coupling agent 1: N-phenyl-3-aminopropyltrimethoxysilane (Toray Dow Corning Co., Ltd., CF-4083) Curing accelerator: Triphenylphosphine (K.I. Chemicals, PP-360) Colorant: Carbon black (Mitsubishi Chemical Corporation, Carbon #5) Ion scavenger: Magnesium hydroxide carbonate hydrate (Kyowa Chemical Industry Co., Ltd., DHT-4H) Wax: Synthetic wax (Clariant Chemicals, WE-4) Flame retardant: Aluminum hydroxide (Sumitomo Chemical Co., Ltd., CL-303) Low-stress agent: Silicone oil (FZ-3730, manufactured by Toray Dow Corning)

[0120] <Evaluation and measurement> (1) Adhesion strength The adhesion strengths S1, S2, and S3 were measured according to the following procedure a. The results are shown in Table 1. [Step a] The easily dismantlable resin composition was molded onto a copper substrate under conditions of 175°C, 6.9 MPa, and 120 seconds, and then post-cured at 175°C for 4 hours to obtain test piece a. Using test piece a, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300 μm / sec. The adhesion strength [N / mm 2 ] to S1 [N / mm 2 ]. In addition, after heating the test piece a at 180°C for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300µm / sec. The adhesion strength [N / mm 2 ] to S2 [N / mm 2 ]. In addition, after heating the test piece a at 300°C for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300µm / sec. The adhesion strength [N / mm 2 ] to S3 [N / mm 2 ].

[0121] (2) SEM observation Each of the obtained easily dismantlable resin compositions was molded onto a nickel plate at 175°C, 6.9 MPa, and for 120 seconds, and then post-cured at 175°C for 4 hours to obtain a test specimen. The test piece was cut in the center, and the cross section was observed with a scanning electron microscope (SEM) and evaluated according to the following criteria. ◯: A thermally expandable filler with a core-shell structure was confirmed. ×: No thermally expandable filler of the core-shell structure was observed, or the core-shell structure was present but the internal gas had escaped.

[0122] (3) Expansion rate The expansion rate (%) was calculated according to the following procedure b and evaluated based on the following criteria. The results are shown in Table 1. [Step b] The easily dismantlable resin composition was molded under conditions of 175°C, 9.8 MPa, and 120 seconds, and then post-cured at 175°C for 4 hours to obtain test piece b (length 10 mm, width 80 mm, thickness 4 mm). Test piece b was heated at 300°C for 30 minutes, and then its vertical and horizontal lengths were measured. The percentage change (%) relative to the vertical length of test piece b before heating and the percentage change (%) relative to the horizontal length of test piece b before heating were calculated, and the average of the percentage changes (%) was taken as the expansion coefficient (%). (standard) ○: Expansion rate is less than 1% ×: Expansion rate exceeds 1%

[0123] (4)Easy disassembly Each of the obtained easily dismantlable resin compositions was molded onto a nickel plate at 175°C, 6.9 MPa, and for 120 seconds, and then post-cured at 175°C for 4 hours to obtain a test specimen. Furthermore, the test pieces were heated at 300°C for 30 minutes, cooled to room temperature, and evaluated for ease of dismantling according to the following criteria. (standard) ◯: The cured product of the test piece was peeled off from the nickel plate. ×: The cured test piece did not peel off from the nickel plate.

[0124] In Examples 1 to 4, a core-shell structure of the thermally expandable filler was confirmed by SEM observation, and easy dismantling was achieved despite the low expansion coefficient. This is thought to be because the thermally expandable filler (C) maintained the core-shell structure and did not expand in the cured product (Examples 1 and 4), or only partially expanded (Examples 2 and 3), but by expanding upon subsequent heating, it was possible to increase the internal pressure of the cured product, thereby realizing the easy dismantling of the cured product.

[0125] [Table 1] [Explanation of symbols]

[0126] 1 case 1a cylindrical part 1b side plate part 2 rotors 3 rotation axes 3a bearing 4 stator 5 permanent magnets 6 Yoke 7 teeth part 8 slots 9 coils 20 Liner material 21 semiconductor elements 30 boards 32 die pad 34 outer lead 40 wire 41 stator core 50 resin layers 51 Encapsulating material 65 Resin sealing part 71 Teeth tip 72 walls 100 rotors 200 Power Module 101 Motor 110 rotor core 118a end plate 118b end plate 120 magnets 130 Fixing member 140 separation part 150 holes 170 rotation shaft

Claims

1. An easily dismantlable resin composition comprising a thermosetting resin and a thermally expandable filler having a core-shell structure.

2. An easily dismantlable resin composition containing a thermosetting resin, wherein the adhesive strength ratio (S2 / S1) measured by the following procedure a is 0.95 to 1.05, and the adhesive strength ratio (S3 / S1) is less than 0.

020. [Step a] The easily dismantlable resin composition was molded onto a copper substrate at 175°C, 6.9 MPa, and for 120 seconds, and then post-cured at 175°C for 4 hours to obtain a test piece a. Using the test piece a, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300 μm / sec. The adhesion strength [N / mm ２ ] to S1 [N / mm ２ ] Further, after heating the test piece a at 180° C. for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300 μm / sec. The adhesion strength [N / mm ２ ] to S2 [N / mm ２ ] Further, after heating the test piece a at 300° C. for 30 minutes, the shear adhesion to the copper substrate was measured at room temperature at a rate of 300 μm / sec. The adhesion strength [N / mm ２ ] to S3 [N / mm ２ ]

3. The easily dismantlable resin composition according to claim 1 or 2, The easily dismantlable resin composition, wherein the expansion starting temperature of the thermally expandable filler is equal to or higher than the molding temperature of the easily dismantlable resin composition.

4. The easily dismantlable resin composition according to claim 1 or 2, The easily dismantlable resin composition, wherein the thermally expandable filler encapsulates a volatile substance or a low-boiling substance.

5. The easily dismantlable resin composition according to claim 1 or 2, The easily dismantlable resin composition has a content of the thermally expandable filler of 1 to 20% by mass relative to the total amount of the easily dismantlable resin composition.

6. The easily dismantlable resin composition according to claim 1 or 2, The easily dismantlable resin composition, wherein the thermosetting resin contains an epoxy resin.

7. The easily dismantlable resin composition according to claim 1 or 2, An easily dismantlable resin composition further comprising a curing agent.

8. The easily dismantlable resin composition according to claim 7, The easily dismantlable resin composition, wherein the curing agent comprises a phenol-based curing agent.

9. The easily dismantlable resin composition according to claim 1 or 2, An easily dismantlable resin composition in the form of powder, granules, or tablets.

10. A cured product of the easily dismantlable resin composition according to claim 1 or 2.

11. The cured product according to claim 10, The cured product contains a thermally expandable filler having a core-shell structure.

12. A structure comprising a cured product of the easily dismantlable resin composition according to claim 1 or 2.

13. The method for dismantling a structure according to claim 12, A method for dismantling a structure, comprising the step of heating the structure to dismantle the cured product of the easily dismantlable resin composition.

14. A method for recycling materials constituting the structure according to claim 12, comprising: a step of heating the structure to dismantle the cured product of the easily dismantlable resin composition; and recovering said material from said structure.

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