Resin compositions, electronic devices, rotors, and motors

Abstract

To provide a resin composition with improved thermal conductivity. [Solution] A resin composition that can be used in one or more molding methods selected from the group consisting of transfer molding, compression molding and injection molding, comprising a thermosetting resin and alumina fibers.

Description

[Technical Field]

[0001] This invention relates to resin compositions, electronic devices, rotors, and motors. [Background technology]

[0002] Thermally conductive resin compositions are used as encapsulants for electronic components. Furthermore, thermally conductive resin compositions are used as fixing materials for securing magnets in holes in structures such as rotors. Examples of technologies relating to resin compositions having thermal conductivity include the technology described in Patent Document 1.

[0003] Patent Document 1 describes a thermally conductive resin composition that can form a cured product with excellent low-temperature curability and handling properties, as well as excellent thermal conductivity, and includes the following components (A) to (C). (A) Epoxy resin (B) Adduct-type latent curing agent that is solid at 25°C (C) A mixture of the following components (C1) to (C3), wherein the mass ratio of component (C1) to component (C3) is 0.14 to 1.0, and the mass ratio of component (C2) to component (C3) is 0.25 to 1.5; (C1) Thermally conductive powder with an average particle size of 0.01 μm or more and less than 2 μm (C2) Thermally conductive powder with an average particle size of 2 μm or more and less than 20 μm (C3) Thermally conductive powder with an average particle size of 20 μm or more and less than 150 μm. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-078170 [Overview of the project] [Problems that the invention aims to solve]

[0005] This invention provides a resin composition with improved thermal conductivity. [Means for solving the problem]

[0006] The inventors diligently conducted research to achieve the above objectives. As a result, they discovered that the thermal conductivity of the resin composition can be improved by including alumina fibers, and thus completed the present invention.

[0007] [1] A resin composition that can be used in one or more molding methods selected from the group consisting of transfer molding, compression molding, and injection molding, Thermosetting resin and Alumina fibers and, A resin composition containing the following: [2] The resin composition according to [1] above, wherein the alumina fibers contain α-alumina. [3] The resin composition according to [2] above, wherein the α-alumina content is 50.0% by mass or more when the total amount of alumina fibers is taken as 100% by mass. [4] A resin composition according to any of [1] to [3] above, wherein the average fiber length of the alumina fibers according to the method described below (Method 1) is 10 μm or more and 1000 μm or less. (Method 1) After dissolving the above resin composition in acetone to remove the resin components, a sample is obtained by dispersing the insoluble matter on a glass plate. For the above sample, the filler in the insoluble matter is photographed using an optical microscope, and the fiber length of the alumina fibers is measured using an image analysis device. The average fiber length (μm) is defined as the average value Lv of the fiber length of 100 of the above alumina fibers, based on the volume of the fibers in the following formula (1), starting with the longest fiber length. Lv = Σ(L × v) / Σv ... Equation (1) Here, Σ represents a set, L represents the length of each alumina fiber, and v represents the volume of each alumina fiber. [5] The resin composition according to any one of [1] to [4] above, wherein the average fiber diameter of the alumina fiber is 0.1 μm or more and 20 μm or less according to Method A (profile method) of JIS R 3420:2013. [6] The resin composition according to any one of [1] to [5] above, wherein the content of the alumina fiber is 1.0% by mass or more and 40.0% by mass or less when the total solid content of the resin composition is 100% by mass. [7] The resin composition according to any one of [1] to [6] above, wherein the thermosetting resin contains an epoxy resin. [8] The resin composition according to [7] above, wherein the epoxy resin contains one or more selected from the group consisting of phenol novolac type epoxy resin, cresol novolac type epoxy resin, and biphenyl type epoxy resin. [9] The resin composition according to any one of [1] to [8] above, wherein the content of the thermosetting resin is 1.0% by mass or more and 40.0% by mass or less when the total solid content of the resin composition is 100% by mass.

[10] The resin composition according to any one of [1] to [9] above, further comprising a curing agent.

[11] The resin composition according to

[10] above, wherein the curing agent contains a phenolic resin-based curing agent.

[12] The resin composition according to

[10] or

[11] above, wherein the content of the curing agent is 1.0% by mass or more and 10.0% by mass or less when the total solid content of the resin composition is 100% by mass.

[13] The resin composition according to any one of [1] to

[12] above, further comprising an inorganic filler (excluding the above alumina fiber).

[14] The resin composition according to

[13] above, wherein the inorganic filler contains one or more selected from the group consisting of silica, alumina particles, kaolin, talc, clay, mica, rock wool, wollastonite, glass powder, glass flakes, glass beads, glass fibers, silicon carbide, silicon nitride, aluminum nitride, calcium carbonate and calcium sulfate.

[15] The resin composition according to

[13] or

[14] above, wherein the content of the inorganic filler is 50.0% by mass or more and 90.0% by mass or less when the total solid content of the resin composition is 100% by mass.

[16] The resin composition according to any one of [1] to

[15] above, which is in powder form, granular form or tablet form.

[17] The resin composition according to any one of [1] to

[16] above, wherein the flexural strength by the following (Method 2) is 10 MPa or more and 300 MPa or less. (Method 2) Using a transfer molding machine, the resin composition is injection molded under the conditions of a mold temperature of 175 °C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a molded product having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. For the obtained molded product, the flexural strength is measured at an ambient temperature of 25 °C in accordance with JIS K 6911:2006.

[18] The resin composition according to any one of [1] to

[17] above, wherein the flexural modulus by the following (Method 3) is 1.0 GPa or more and 100.0 GPa or less. (Method 3) Using a transfer molding machine, the resin composition is injection molded under the conditions of a mold temperature of 175 °C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a molded product having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. For the obtained molded product, the flexural modulus is measured at an ambient temperature of 25 °C in accordance with JIS K 6911:2006.

[19] The storage elastic modulus E' at 25 °C by the following (Method 4) 25 The resin composition according to any one of [1] to

[18] above, which is 1.0 GPa or more and 100.0 GPa or less. (Method 4) Using a transfer molding machine, the above resin composition was injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of the obtained test specimen was measured at 25°C using a dynamic viscoelasticity analyzer under the conditions of tensile mode and frequency of 10 Hz.

[20] Storage modulus E' at 260°C according to the method (Method 5) below 260 A resin composition according to any of the above [1] to

[19] , wherein the pressure is 0.1 GPa or more and 10.0 GPa or less. (Method 5) Using a transfer molding machine, the above resin composition was injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of the obtained test specimen was measured at 260°C using a dynamic viscoelasticity analyzer under the conditions of tensile mode and frequency of 10 Hz. [twenty one] A resin composition according to any of the above [1] to

[20] , wherein the glass transition temperature according to the following method (6) is 70°C or higher and 300°C or lower. (Method 6) Using a transfer molding machine, the above resin composition was injected and molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The tanδ of the obtained test specimen was measured using a dynamic viscoelasticity analyzer under the conditions of a heating rate of 5°C / min, a frequency of 10 Hz, and a load of 800 g, and the temperature at the peak of tanδ was read as the glass transition temperature. [twenty two] A resin composition according to any one of the above [1] to

[21] , which can be used for encapsulating electronic components. [twenty three] A resin composition according to any one of the above [1] to

[21] , which can be used to seal the coils of a stator core. [twenty four] A resin composition according to any one of the above [1] to

[21] , which can be used to fix a magnet in the hole of a rotor core. [twenty five] The device comprises an electronic component and a sealing material for sealing the electronic component, An electronic device wherein the sealing material includes a cured product of any of the resin compositions described in [1] to

[21] above.

[26] It comprises a rotor core having a hole, a magnet in the hole, and a fixing material for fixing the magnet in the hole, A rotor in which the fixing material includes a cured product made from any of the resin compositions described in [1] to

[21] above.

[27] A motor having the rotor described above

[26] . [Effects of the Invention]

[0008] According to the present invention, a resin composition with improved thermal conductivity can be provided. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Unless otherwise specified, the numerical range "A to B" represents A or greater and B or less.

[0010] <Resin composition> The resin composition of this embodiment is a resin composition that can be used in one or more molding methods selected from the group consisting of transfer molding, compression molding, and injection molding, and comprises a thermosetting resin and alumina fibers.

[0011] The resin composition of this embodiment can improve thermal conductivity. This is because alumina fibers have excellent thermal conductivity, and their fibrous nature allows for the efficient formation of heat conduction paths within the resin composition.

[0012] The resin composition of this embodiment can be used in one or more molding methods selected from the group consisting of transfer molding, compression molding, and injection molding, and is preferably used in transfer molding. The conditions in transfer molding are not particularly limited, but for example, the mold temperature is 150°C to 250°C, and the pressure when injecting the molten resin composition into the mold is 5.0 MPa to 15.0 MPa. The temperature at which the resin composition melts can be considered to be the same as the mold temperature.

[0013] The resin composition of this embodiment is preferably in powder, granular, or tablet form, from the viewpoint of improving the balance between handling and moldability.

[0014] The following describes each component used in the resin composition of this embodiment.

[0015] [Thermosetting resin] The resin composition of this embodiment includes a thermosetting resin. From the viewpoint of further improving thermal conductivity, the thermosetting resin preferably includes one or more selected from the group consisting of epoxy resin, phenolic resin, bismaleimide resin, benzoxazine resin, urea resin, melamine resin, etc., unsaturated polyester resin, polyurethane resin, diallyl phthalate resin, silicone resin, cyanate resin, polyimide resin, polyamideimide resin, and benzocyclobutene resin. From the viewpoint of further improving the balance of performance of thermal conductivity, fluidity, and the mechanical properties of the cured resin composition, it more preferably includes an epoxy resin.

[0016] The epoxy resins of this embodiment are preferably novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins, from the viewpoint of further improving the balance of performance in thermal conductivity, fluidity and the mechanical properties of the cured resin composition; 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; alkyl-modified triphenolmethane-type epoxy resins; triazine nucleus-containing epoxy resins; dicyclo The epoxy resin comprises one or more selected from the group consisting of pentadiene-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 alicyclic epoxy resins such as vinylcyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diepoxy adipade. More preferably, it comprises one or more selected from the group consisting of phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and biphenyl-type epoxy resins, which can further improve the balance of performance in terms of thermal conductivity, fluidity, and the mechanical properties of the cured resin product.

[0017] The phenolic resin of this embodiment preferably includes one or more types selected from the group consisting of novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin, and resol-type phenolic resins.

[0018] In the resin composition of this embodiment, the content of thermosetting resin is preferably 1.0% to 40.0% by mass, more preferably 2.0% to 30.0% by mass, even more preferably 3.0% to 25.0% by mass, even more preferably 4.0% to 20.0% by mass, and even more preferably 4.5% to 17.0% by mass, when the total solid content of the resin composition is considered as 100% by mass, from the viewpoint of further improving the balance of performance of thermal conductivity, fluidity, and the mechanical properties of the cured resin composition.

[0019] [Alumina fiber] The resin composition of this embodiment contains alumina fibers. From the viewpoint of further improving thermal conductivity, the alumina fibers preferably include one or more selected from the group consisting of α-alumina, θ-alumina, γ-alumina, and δ-alumina, and more preferably include α-alumina.

[0020] When the resin composition of this embodiment contains α-alumina, the α-alumina content is preferably 50.0% by mass or more and 100% by mass or less, more preferably 60.0% by mass or more and 100% by mass or less, even more preferably 70.0% by mass or more and 100% by mass or less, even more preferably 80.0% by mass or more and 100% by mass or less, even more preferably 90.0% by mass or more and 100% by mass or less, and even more preferably 95.0% by mass or more and 100% by mass or less, when the total amount of alumina fibers is considered to be 100% by mass, from the viewpoint of further improving thermal conductivity.

[0021] In the resin composition of this embodiment, the lower limit of the average fiber length of the alumina fibers according to the following (Method 1) is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 40 μm or more, even more preferably 50 μm or more, even more preferably 60 μm or more, even more preferably 70 μm or more, and even more preferably 75 μm or more, from the viewpoint of further improving the balance of performance between thermal conductivity and the mechanical properties of the cured resin composition. Furthermore, the upper limit of the average fiber length of the alumina fibers is not particularly limited, but from the viewpoint of improving the fluidity of the resin composition, it may be 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or 300 μm or less. In other words, the average fiber length of the alumina fibers is preferably 10 μm to 1000 μm, more preferably 20 μm to 900 μm, even more preferably 30 μm to 800 μm, even more preferably 40 μm to 700 μm, even more preferably 50 μm to 600 μm, even more preferably 60 μm to 500 μm, even more preferably 70 μm to 400 μm, and even more preferably 75 μm to 300 μm, from the viewpoint of further improving the balance of performance in terms of thermal conductivity, mechanical properties of the cured resin composition, and fluidity of the resin composition.

[0022] (Method 1) After dissolving the above resin composition in acetone to remove the resin components, a sample is obtained by dispersing the insoluble matter on a glass plate. For the above sample, the filler in the insoluble matter is photographed using an optical microscope, and the fiber length of the alumina fibers is measured using an image analysis device. The average fiber length (μm) is defined as the average value Lv of the fiber length of 100 of the above alumina fibers, based on the volume of the fibers in the following formula (1), starting with the longest fiber length. Lv = Σ(L × v) / Σv ... Equation (1) Here, Σ represents a set, L represents the length of each alumina fiber, and v represents the volume of each alumina fiber.

[0023] In the resin composition of this embodiment, the lower limit of the average fiber diameter of alumina fibers according to Method A (contour method) of JIS R 3420:2013 is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1.0 μm or more, even more preferably 3.0 μm or more, and even more preferably 5.0 μm or more, from the viewpoint of further improving the balance of performance between thermal conductivity and the mechanical properties of the cured resin composition. Furthermore, while the upper limit of the average fiber diameter of the alumina fibers is not particularly limited, from the viewpoint of improving the fluidity of the resin composition, it may be 20 μm or less, 18 μm or less, 15 μm or less, 13 μm or less, or 10 μm or less. In other words, the average fiber diameter of the alumina fibers is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 18 μm, even more preferably 1.0 μm to 15 μm, even more preferably 3.0 μm to 13 μm, and even more preferably 5.0 μm to 10 μm, from the viewpoint of further improving the balance of performance in thermal conductivity, mechanical properties of the cured resin composition, and fluidity of the resin composition.

[0024] In the resin composition of this embodiment, the alumina fiber content is preferably 1.0% to 40.0% by mass, more preferably 2.0% to 35.0% by mass, even more preferably 3.0% to 30.0% by mass, and even more preferably 4.0% to 25.0% by mass, when the total solid content of the resin composition is considered to be 100% by mass, from the viewpoint of further improving the balance between thermal conductivity and the mechanical properties of the cured resin composition.

[0025] [Hardening agent] The resin composition of this embodiment preferably includes a curing agent, from the viewpoint of further improving the balance of performance in terms of thermal conductivity, moldability, and the mechanical properties of the cured resin composition.

[0026] The curing agent of this embodiment preferably comprises one or more selected from the group consisting of phenolic resin curing agents, amine curing agents, acid anhydride curing agents, and mercaptan curing agents, and more preferably comprises a phenolic resin curing agent, from the viewpoint of further improving the balance of performance of thermal conductivity, moldability, and mechanical properties of the cured resin composition.

[0027] The phenolic resin curing agent of this embodiment preferably comprises one or more selected from the group consisting of phenolic novolac resins, cresol novolac resins, and other phenols such as phenol, cresol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, aminophenol, α-naphthol, β-naphthol, and dihydroxynaphthalene, and formaldehyde or ketones under an acidic catalyst; phenolic aralkyl resins having a phenylene skeleton synthesized from the above-mentioned phenols and dimethoxyp-xylene or bis(methoxymethyl)biphenyl; phenolic aralkyl resins having a biphenylene skeleton; and phenolic resins having a trisphenylmethane skeleton. More preferably, it comprises one or more selected from the group consisting of phenolic novolac resins and cresol novolac resins.

[0028] The amine-based curing agent of this embodiment preferably comprises one or more selected from the group consisting of aliphatic polyamines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylylenediamine (MXDA); aromatic polyamines such as diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diaminodiphenylsulfone (DDS); and polyamine compounds such as dicyandiamide (DICY) and organic acid dihydrarazine.

[0029] The acid anhydride-based curing agent of this embodiment preferably comprises one or more selected from the group consisting of alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), and maleic anhydride; and aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), benzophenonetetracarboxylic acid (BTDA), and phthalic anhydride.

[0030] The mercaptan-based curing agent of this embodiment preferably comprises one or more selected from the group consisting of trimethylolpropanetris(3-mercaptobutyrate) and trimethylolethanetris(3-mercaptobutyrate).

[0031] In the resin composition of this embodiment, the curing agent content is preferably 1.0% to 10.0% by mass, more preferably 1.0% to 9.0% by mass, even more preferably 1.5% to 8.0% by mass, even more preferably 2.0% to 7.0% by mass, and even more preferably 2.5% to 6.0% by mass, when the total solid content of the resin composition is considered as 100% by mass, from the viewpoint of further improving the balance of performance of thermal conductivity, moldability, and the mechanical properties of the cured resin composition.

[0032] [Curing accelerator] The resin composition of this embodiment preferably includes a curing accelerator, from the viewpoint of further improving the balance of performance in terms of thermal conductivity, moldability, and the mechanical properties of the cured resin composition.

[0033] In the resin composition of this embodiment, the curing accelerator can be any substance that promotes the crosslinking reaction with the thermosetting resin and curing agent, and any substance used in general resin compositions can be used. Among these, the curing accelerator preferably includes one or more selected from the group consisting of imidazole-based curing accelerators; phosphorus-based catalysts such as tetraphenylphosphonium-2,3-dihydroxynaphthalate; diazabicycloalkenes such as 1,8-diazabicyclo(5,4,0)undecene-7 and their derivatives; organophosphines such as triphenylphosphine and methyldiphenylphosphine; and tetra-substituted phosphonium / tetra-substituted borates such as tetraphenylphosphonium / tetraphenylborate.

[0034] The imidazole-based curing accelerator of this embodiment is preferably imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl- It comprises one or more selected from the group consisting of 2-phenylimidazolium trimelate, 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4-methylimidazolyl(1')]-ethyl-s-triazine, isocyanuric acid adducts of 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, isocyanuric acid adducts of 2-phenylimidazole, isocyanuric acid adducts of 2-methylimidazole, 2-phenyl-4,5-dihydroxydimethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

[0035] In the resin composition of this embodiment, the content of the curing accelerator is preferably 0.01% to 3.0% by mass, more preferably 0.03% to 2.5% by mass, even more preferably 0.05% to 2.0% by mass, even more preferably 0.08% to 1.0% by mass, and even more preferably 0.10% to 0.5% by mass, when the total solid content of the resin composition is considered to be 100% by mass, from the viewpoint of further improving the balance of performance of thermal conductivity, moldability, and the mechanical properties of the cured resin composition.

[0036] [Inorganic filler] The resin composition of this embodiment preferably includes an inorganic filler (excluding the alumina fibers mentioned above) from the viewpoint of further improving the balance of performance in terms of thermal conductivity, fluidity, and the mechanical properties of the cured resin composition.

[0037] The inorganic filler of this embodiment preferably includes fused silica such as fused crushed silica and fused spherical silica, silica such as crystalline silica, fumed silica or precipitated silica, alumina particles (excluding alumina fibers), kaolin, talc, clay, mica, rock wool, wollastonite, glass powder, glass flakes, glass beads, glass fibers, silicon carbide, silicon nitride, aluminum nitride, aluminosilicate, graphite, titanium dioxide, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, sulfur It comprises one or more selected from the group consisting of barium acid, cellulose, aramid, wood, and pulverized powder obtained by crushing cured phenolic resin molding materials or epoxy resin molding materials, more preferably comprising one or more selected from the group consisting of silica, alumina particles, kaolin, talc, clay, mica, rock wool, wollastonite, glass powder, glass flakes, glass beads, glass fibers, silicon carbide, silicon nitride, aluminum nitride, calcium carbonate, and calcium sulfate, and even more preferably comprising one or more selected from the group consisting of silica, alumina particles, wollastonite, and glass beads.

[0038] Average particle diameter D in the volume-based particle size distribution of inorganic fillers, measured by laser diffraction scattering particle size distribution analysis. 50 From the viewpoint of further improving the balance of performance in thermal conductivity, fluidity, and the mechanical properties of the cured resin composition, the particle size is preferably 0.01 μm to 100 μm, more preferably 0.1 μm to 50 μm, and even more preferably 0.3 μm to 30 μm. Average particle size D of inorganic filler 50For example, the measured value at 50% of the cumulative volume-based particle size distribution obtained by the laser diffraction scattering measurement method using a laser diffraction particle size distribution analyzer (SALD-7000, manufactured by Shimadzu Corporation) can be used.

[0039] Furthermore, in the resin composition of this embodiment, from the viewpoint of further improving the balance of performance between thermal conductivity, fluidity, and the mechanical properties of the cured resin composition, the inorganic filler is preferably of average particle size D 50 It contains two or more different types of inorganic fillers.

[0040] In the resin composition of this embodiment, the inorganic filler content is preferably 50.0% to 90.0% by mass, more preferably 53.0% to 89.0% by mass, even more preferably 55.0% to 88.0% by mass, even more preferably 58.0% to 87.0% by mass, and even more preferably 60.0% to 86.0% by mass, when the total solid content of the resin composition is considered as 100% by mass, from the viewpoint of further improving the balance of performance of thermal conductivity, fluidity, and the mechanical properties of the cured resin composition.

[0041] [Other ingredients] The resin composition of this embodiment may optionally contain a silane coupling agent, a colorant, an ion scavenger, an adhesion aid, a stress reducer, a mold release agent, an antioxidant, and the like.

[0042] (Silane coupling agent) The resin composition of this embodiment may contain a silane coupling agent from the viewpoint of further improving the adhesion between the thermosetting resin and the alumina fibers. The resin composition of this embodiment may contain known silane coupling agents, but preferably contains one or more selected from the group consisting of epoxysilane, aminosilane, ureidosilane, and mercaptosilane.

[0043] The epoxysilane of this embodiment preferably comprises one or more selected from the group consisting of γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The aminosilane of this embodiment preferably includes one or more selected from the group consisting of primary aminosilanes such as γ-aminopropyltriethoxysilane and γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-phenylγ-aminopropyltriethoxysilane, N-phenylγ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-6-(aminohexyl)3-aminopropyltrimethoxysilane, and N-(3-(trimethoxysilylpropyl)-1,3-benzenedimethanane. The ureidosilane of this embodiment preferably comprises one or more selected from the group consisting of γ-ureidopropyltriethoxysilane and hexamethyldisilazane. The mercaptosilane of this embodiment preferably comprises one or more selected from the group consisting of γ-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfide, and bis(3-triethoxysilylpropyl)disulfide. Furthermore, the silane coupling agent in this embodiment may be formulated after undergoing a hydrolysis reaction in advance.

[0044] When the resin composition of this embodiment contains a silane coupling agent, the content of the silane coupling agent in the resin composition of this embodiment is preferably 0.01% by mass or more and 1.00% by mass or less, more preferably 0.02% by mass or more and 0.75% by mass or less, even more preferably 0.03% by mass or more and 0.50% by mass or less, and even more preferably 0.04% by mass or more and 0.30% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

[0045] (Coloring agent) The resin composition of this embodiment may contain a colorant. The resin composition of this embodiment may contain known colorants as the colorant. The colorant of this embodiment preferably contains one or more selected from the group consisting of carbon black, red iron oxide, and titanium dioxide.

[0046] If the resin composition of this embodiment contains a coloring agent, the amount of coloring agent in the resin composition of this embodiment is preferably 0.01% by mass or more and 1.00% by mass or less, more preferably 0.10% by mass or more and 0.50% by mass or less, and even more preferably 0.20% by mass or more and 0.30% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

[0047] (Ion scavenger) The resin composition of this embodiment may contain an ion scavenger. The resin composition of this embodiment may contain known ion scavengers as the ion scavenger. The ion scavenger of this embodiment preferably contains one or more selected from the group consisting of hydrotalcite, bismuth oxide, and yttrium oxide.

[0048] When the resin composition of this embodiment contains an ion scavenger, the content of the ion scavenger in the resin composition of this embodiment is preferably 0.01% by mass or more and 0.50% by mass or less, more preferably 0.05% by mass or more and 0.30% by mass or less, and even more preferably 0.10% by mass or more and 0.20% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

[0049] (Adhesion enhancer) The resin composition of this embodiment may contain an adhesion aid. The resin composition of this embodiment may contain known adhesion aids. The adhesion aid of this embodiment preferably includes one or more selected from the group consisting of amides such as 2-hydroxy-N-1H-1,2,4-triazole-3-yl-benzamide and triazine compounds such as the compound represented by the following chemical formula (14).

[0050] [ka]

[0051] In the above chemical formula (14), R represents an aliphatic chain having 1 to 15 carbon atoms.

[0052] If the resin composition of this embodiment contains an adhesion aid, the content of the adhesion aid in the resin composition of this embodiment is preferably 0.01% by mass or more and 0.50% by mass or less, more preferably 0.02% by mass or more and 0.30% by mass or less, and even more preferably 0.03% by mass or more and 0.10% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

[0053] (Stress-reducing agent) The resin composition of this embodiment may contain a low-stress agent. The resin composition of this embodiment may contain a known low-stress agent. The low-stress agent of this embodiment preferably comprises one or more selected from the group consisting of silicone oil, silicone resin, silicone rubber, polyisoprene, polybutadiene such as 1,2-polybutadiene and 1,4-polybutadiene, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polychloroprene, poly(oxypropylene), poly(oxytetramethylene) glycol, polyolefin glycol, thermoplastic elastomer such as poly-ε-caprolactone, polysulfide rubber, and fluororubber, and more preferably comprises one or more selected from the group consisting of silicone oil, silicone resin, silicone rubber, and thermoplastic elastomer.

[0054] When the resin composition of this embodiment contains a low-stress agent, the content of the low-stress agent in the resin composition of this embodiment is preferably 0.10% by mass or more and 5.00% by mass or less, more preferably 0.50% by mass or more and 4.00% by mass or less, even more preferably 0.75% by mass or more and 3.00% by mass or less, and even more preferably 1.00% by mass or more and 2.00% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

[0055] (Release agent) The resin composition of this embodiment may contain a mold release agent. The resin composition of this embodiment may contain a known mold release agent. The mold release agent of this embodiment preferably contains one or more selected from the group consisting of natural waxes, carnauba wax, montanic acid esters, ethylene glycol montanate esters, reaction products of alkenes and carboxylic acid anhydrides and alcohols, higher fatty acids such as stearic acid and zinc stearate or their metal salts, carboxylic acid amides such as erucic acid amide, paraffin and polyethylene oxide.

[0056] If the resin composition of this embodiment contains a release agent, the content of the release agent in the resin composition of this embodiment is preferably 0.01% by mass or more and 3.00% by mass or less, more preferably 0.10% by mass or more and 2.00% by mass or less, and even more preferably 0.15% by mass or more and 1.50% by mass or less, when the total solid content of the resin composition is taken as 100% by mass.

[0057] [Physical properties of resin compositions] In the resin composition of this embodiment, the bending strength obtained by the following (Method 2) is preferably 10 MPa to 300 MPa, more preferably 20 MPa to 275 MPa, even more preferably 30 MPa to 250 MPa, even more preferably 40 MPa to 225 MPa, even more preferably 50 MPa to 200 MPa, and even more preferably 60 MPa to 175 MPa, from the viewpoint of further improving the performance balance of the mechanical properties of the cured product of the thermally conductive resin composition.

[0058] (Method 2) Using a transfer molding machine, the above resin composition was injected under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a molded product with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The bending strength of the obtained molded product was measured in accordance with JIS K 6911:2006 at an ambient temperature of 25°C.

[0059] In the resin composition of this embodiment, the flexural modulus obtained by the following method (3) is preferably 1.0 GPa or more and 100.0 GPa or less, more preferably 3.0 GPa or more and 90.0 GPa or less, even more preferably 5.0 GPa or more and 80.0 GPa or less, even more preferably 8.0 GPa or more and 60.0 GPa or less, and even more preferably 10.0 GPa or more and 50.0 GPa or less, from the viewpoint of further improving the performance balance of the mechanical properties of the cured product of the thermally conductive resin composition.

[0060] (Method 3) Using a transfer molding machine, the above resin composition was injected under the conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a molded product with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The flexural modulus of the obtained molded product was measured in accordance with JIS K 6911:2006 at an ambient temperature of 25°C.

[0061] In the resin composition of this embodiment, the storage modulus E' at 25°C is determined by the following method (Method 4). 25 From the viewpoint of further improving the performance balance of the mechanical properties of the cured product of the thermally conductive resin composition, the preferred range is 1.0 GPa to 100.0 GPa, more preferably 3.0 GPa to 80.0 GPa, even more preferably 5.0 GPa to 60.0 GPa, even more preferably 8.0 GPa to 40.0 GPa, and even more preferably 10.0 GPa to 35.0 GPa.

[0062] (Method 4) Using a transfer molding machine, the above resin composition was injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of the obtained test specimen was measured at 25°C using a dynamic viscoelasticity analyzer under the conditions of tensile mode and frequency of 10 Hz.

[0063] In the resin composition of this embodiment, the storage modulus E' at 260°C is determined by the following method (Method 5). 260From the viewpoint of further improving the performance balance of the mechanical properties of the cured product of the thermally conductive resin composition, the thermal conductivity is preferably 0.1 GPa or more and 10.0 GPa or less, more preferably 0.3 GPa or more and 8.0 GPa or less, even more preferably 0.5 GPa or more and 6.0 GPa or less, even more preferably 0.8 GPa or more and 4.0 GPa or less, and even more preferably 1.0 GPa or more and 3.0 GPa or less.

[0064] (Method 5) Using a transfer molding machine, the above resin composition was injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of the obtained test specimen was measured at 260°C using a dynamic viscoelasticity analyzer under the conditions of tensile mode and frequency of 10 Hz.

[0065] In the resin composition of this embodiment, the glass transition temperature according to the following (Method 6) is preferably 70°C to 300°C, more preferably 80°C to 275°C, even more preferably 90°C to 250°C, even more preferably 100°C to 230°C, and even more preferably 110°C to 210°C, from the viewpoint of further improving the performance balance of the mechanical properties of the cured product of the thermally conductive resin composition.

[0066] (Method 6) Using a transfer molding machine, the above resin composition was injected and molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The tanδ of the obtained test specimen was measured using a dynamic viscoelasticity analyzer under the conditions of a heating rate of 5°C / min, a frequency of 10 Hz, and a load of 800 g, and the temperature at the peak of tanδ was read as the glass transition temperature.

[0067] In measuring the physical properties of the resin composition of this embodiment, a transfer molding machine such as the KTS-15, manufactured by Kotaki Seiki Co., Ltd., can be used. Furthermore, a dynamic viscoelasticity measuring instrument such as the DMA-6100, manufactured by Hitachi High-Tech Corporation, can be used.

[0068] [Method for producing resin compositions] The resin composition of this embodiment can be manufactured by uniformly mixing the above components in a mixer or blender such as a tumbler mixer or Henschel mixer to a predetermined content, and then kneading while heating in a kneader, roll mixer, disper mixer, adi-homogenizer mixer, or planetary mixer. The temperature during kneading must be within a temperature range in which no curing reaction occurs, and although it depends on the composition of the resin composition, it is preferable to melt-knead at around 70 to 150°C. After kneading, the mixture may be cooled and solidified, and the kneaded material may be processed into a powder, granules, or tablet form.

[0069] One method for obtaining a powdered resin composition is to grind a mixture using a grinding device. Alternatively, the mixture may be formed into a sheet and then ground. Examples of grinding devices include hammer mills, stone mills, and roll crushers.

[0070] As a method for obtaining a granular or tablet-shaped resin composition, for example, a granulation method such as the hot-cut method can be used, in which a small-diameter die is installed at the outlet of a kneading device, and the molten kneaded material discharged from the die is cut to a predetermined length with a cutter or the like. In this case, after obtaining a granular or tablet-shaped resin composition by a granulation method such as the hot-cut method, it is preferable to degas the resin composition before its temperature drops too much.

[0071] [Uses of resin compositions] The resin composition of this embodiment has improved thermal conductivity and can therefore be used for encapsulating electronic components. Examples of electronic components include semiconductor elements, small sensors, wiring boards, integrated circuits, large integrated circuits, transistors, thyristors, diodes, solid-state image sensors, ceramic capacitors, chip resistors, and microcomputers.

[0072] Furthermore, since the resin composition of this embodiment has improved thermal conductivity, it can be used to seal the coils of the stator core. A stator core has multiple teeth, around which coils are wound. At this time, it is necessary to insulate the coils from the stator core, and this insulation can be achieved by interposing a sealing resin composition. The resin composition of this embodiment can be applied in the process of interposing this resin composition. By using the resin composition of this embodiment as a sealing material, it becomes possible to enlarge the stator core and produce multiple cores simultaneously.

[0073] Furthermore, since the resin composition of this embodiment has improved thermal conductivity, it can be used to fix magnets in the holes of the rotor core. The permanent magnets are fixed to the rotor core by inserting them into holes provided in the rotor core and filling the space between the holes and the permanent magnets with a resin composition. The resin composition of this embodiment can be used in the process of filling with the resin composition. By using the resin composition of this embodiment as a sealing material, it becomes possible to enlarge the rotor core and produce multiple cores simultaneously.

[0074] <Electronic equipment> The electronic device of this embodiment comprises an electronic component and a sealing material for sealing the electronic component, wherein the sealing material includes a cured product of the resin composition of this embodiment. Examples of such electronic devices include semiconductor devices applied to memory and logic elements such as dual in-line packages (DIP), plastic-leaded chip carriers (PLCC), quad-flat packages (QFP), low-profile quad-flat packages (LQFP), small outline packages (SOP), small outline J-lead packages (SOJ), thin small outline packages (TSOP), thin quad-flat packages (TQFP), tape carrier packages (TCP), ball grid arrays (BGA), chip-size packages (CSP), matrix array package ball grid arrays (MAPBGA), and chip-stacked chip-size packages; semiconductor devices equipped with power elements such as power transistors; and automotive electronic control units such as engine control units or electronic control units.

[0075] <Rotor> The rotor of this embodiment comprises a rotor core having a hole, a magnet in the hole, and a fixing material for fixing the magnet in the hole, wherein the fixing material includes a cured product made from the resin composition of this embodiment.

[0076] The term "hole" refers to a hole formed perpendicular to the surface direction of the rotor core, and may or may not be a through hole. The rotor core may have at least one hole, or it may have multiple holes.

[0077] The shape of the hole in plan view is not particularly limited and can be, for example, rectangular or circular. Preferably, the shape of the hole in plan view is a rounded shape such as a circle, from the viewpoint of suppressing stress concentration and further improving the strength of the rotor.

[0078] The method for manufacturing the rotor is not particularly limited, but preferably includes a step of inserting a fixing material containing a cured product made of the resin composition into the holes of the rotor core by transfer molding the resin composition of this embodiment. The preferred conditions for transfer molding of the resin composition at this time are as described above.

[0079] <motor> The motor of this embodiment is equipped with the rotor of this embodiment. The motor of this embodiment may further include a shaft, bearings, stator, bracket, etc., in addition to the rotor of this embodiment.

[0080] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0082] <Examples, Comparative Examples> For each example and comparative example, the resin composition was prepared as follows. First, the components shown in Table 1 were mixed using a mixer. Next, the resulting mixture was roll-kneaded, cooled, and pulverized to obtain a powdered resin composition.

[0083] Details of each component in Table 1 are as follows. Furthermore, the formulations shown in Table 1 indicate the content (mass%) of each component when the total solid content of the resin composition is considered to be 100% by mass.

[0084] <Inorganic filler> Inorganic filler 1: Alumina particles (average particle size D 50 :27μm) Inorganic filler 2: Alumina particles (average particle diameter D 50 : 20 μm) Inorganic filler 3: Alumina particles (average particle diameter D 50 : 2.7 μm) Inorganic filler 4: Fused spherical silica (average particle diameter D 50 : 23.9 μm) Inorganic filler 5: Fused spherical silica (average particle diameter D 50 : 12.5 μm) Inorganic filler 6: Fused spherical silica (average particle diameter D 50 : 0.6 μm) Inorganic filler 7: Fumed silica Inorganic filler 8: Precipitated silica (VN3, manufactured by Tosoh Silica Corporation) Inorganic filler 9: Glass fiber (fiber length: 3 mm, fiber diameter: 10 μm) Inorganic filler 10: Aluminosilicate (AST 1360-012, manufactured by HPF) Inorganic filler 11: Wollastonite​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Thermosetting resin 2: Orthocresol novolac type epoxy resin (CNE195LB, manufactured by Changchun Artificial Resin Co., Ltd.) Thermosetting resin 3: Biphenyl-type epoxy resin (YX4000HK, manufactured by Mitsubishi Chemical Corporation) Thermosetting resin 4: Biphenyl-type epoxy resin (YL6677, manufactured by Mitsubishi Chemical Corporation)

[0088] <Hardening agent> Hardener 1: Phenolic novolac type resin (PR-51470, manufactured by Sumitomo Bakelite Co., Ltd.) Hardener 2: Phenol novolac type resin (PR-51714, manufactured by Sumitomo Bakelite Co., Ltd.) Hardener 3: Phenol novolac type resin (PR-55617, manufactured by Sumitomo Bakelite Co., Ltd.)

[0089] <Curing accelerator> Curing accelerator 1: 2-phenyl-4,5-dihydroxymethylimidazole Curing accelerator 2: Tetraphenylphosphonium-2,3-dihydroxynaphthalate

[0090] <Coloring agent> Coloring agent 1: Carbon black

[0091] <Ion scavenger> Ion scavenger 1: Magnesium aluminum hydroxide carbonate hydrate

[0092] <Adhesion enhancer> Adhesion aid 1: 2-hydroxy-N-1H-1,2,4-triazole-3-yl-benzamide Adhesion aid 2: The compound represented by the following chemical formula (14) (R represents an aliphatic chain with 1 to 15 carbon atoms, and this compound is a mixture of these).

[0093] [ka]

[0094] <Low stress agent> Low-stress agent 1: Thermoplastic elastomer Low-stress agent 2: Silicone resin Low stress agent 3: Silicone oil

[0095] <Release agent> Release agent 1: Synthetic wax (reaction product of 1-alkene (C>10) and maleic anhydride condensate with stearyl alcohol) Release agent 2: Ethylene glycol montanoate Release agent 3: Montanate ester Release agent 4: Carnauba wax Release agent 5: Stearic acid Release agent 6: Erucic acid amide

[0096] Here, the average particle size of the inorganic filler was measured using a laser diffraction scattering method with a laser diffraction particle size distribution analyzer (Shimadzu Corporation, model number: SALD-7000) at a cumulative value of 50% of the volume-based particle size distribution.

[0097] Furthermore, the average fiber diameter of the alumina fibers was measured using Method A (contour method) of JIS R 3420:2013.

[0098] [Table 1]

[0099] <Evaluation of physical properties> The following physical properties were measured for the resin compositions obtained in each example and comparative example.

[0100] (Spiral Flow Gel Time) Using a transfer molding machine (manufactured by Kotaki Seiki Co., Ltd., part number: KTS-15), the resin compositions of each example and comparative example were injected into a spiral flow measurement mold conforming to ANSI / ASTM D 3123-72 under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds. The flow length was measured and defined as the spiral flow. In addition, the time from the start of injection until the resin composition cured and ceased to flow was measured and defined as the gel time. The results are shown in Table 2.

[0101] (Thermal conductivity) Using a transfer molding machine (manufactured by Kotaki Seiki Co., Ltd., model number: KTS-15), the resin compositions of each example and comparative example were injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain test specimens with a length of 10 mm, a width of 10 mm, and a thickness of 1 mm. Next, the thermal conductivity (W / (m·K)) in the thickness direction of the test specimens was measured using the laser flash method. The results are shown in Table 2.

[0102] (Bending strength) Using a transfer molding machine (manufactured by Kotaki Seiki Co., Ltd., model number: KTS-15), the resin compositions of each example and comparative example were injected and molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain molded articles with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The bending strength of the obtained molded articles was measured in accordance with JIS K 6911:2006 at an ambient temperature of 25°C. The results are shown in Table 2.

[0103] (Flexural modulus) Using a transfer molding machine (manufactured by Kotaki Seiki Co., Ltd., model number: KTS-15), the resin compositions of each example and comparative example were injected and molded under the conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain molded articles with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The flexural modulus of the obtained molded articles was measured in accordance with JIS K 6911:2006 at an ambient temperature of 25°C. The results are shown in Table 2.

[0104] (Average fiber length) After dissolving the resin compositions of each example and comparative example in acetone to remove the resin components, samples were obtained by dispersing the insoluble matter on a glass plate. For these samples, the fillers in the insoluble matter were photographed using an optical microscope, and the fiber length of the alumina fibers was measured using an image analysis device. The average fiber length (μm) was defined as the average of the fiber lengths of 100 alumina fibers, based on the volume of each fiber, as shown in the following formula (1). The results are shown in Table 2. Lv = Σ(L × v) / Σv ... Equation (1) Here, Σ represents a set, L represents the length of each alumina fiber, and v represents the volume of each alumina fiber.

[0105] (Storage modulus E') 25 and E' 260 ) Using a transfer molding machine (Kotaki Seiki Co., Ltd., part number: KTS-15), the resin compositions of each example and comparative example were injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain test specimens with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of elasticity of the obtained test specimens was measured at 25°C and 260°C using a dynamic viscoelasticity analyzer (Hitachi High-Tech Corporation, part number: DMA-6100) in tensile mode and at a frequency of 10 Hz, and the storage modulus E' was determined. 25 and E' 260 The results are shown in Table 2.

[0106] (Glass transition temperature) Using a transfer molding machine (KOTAKI SEIKI Co., Ltd., model number: KTS-15), the resin compositions of each example and comparative example were injection molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain test specimens with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. For the obtained test specimens, tanδ was measured using a dynamic viscoelasticity analyzer (Hitachi High-Tech Corporation, model number: DMA-6100) under the conditions of a heating rate of 5°C / min, a frequency of 10 Hz, and a load of 800 g, and the temperature at the peak of tanδ was read as the glass transition temperature. The results are shown in Table 2.

[0107] Table 2

Claims

1. A resin composition that can be used in one or more molding methods selected from the group consisting of transfer molding, compression molding, and injection molding, Thermosetting resin and Alumina fibers and, A resin composition containing the following:

2. The resin composition according to claim 1, wherein the alumina fibers contain α-alumina.

3. The resin composition according to claim 2, wherein the α-alumina content is 50.0% by mass or more when the total amount of alumina fibers is 100% by mass.

4. The resin composition according to any one of claims 1 to 3, wherein the average fiber length of the alumina fibers obtained by the following method (Method 1) is 10 μm or more and 1000 μm or less. (Method 1) After dissolving the resin composition in acetone to remove the resin components, a sample is obtained by dispersing the insoluble matter on a glass plate. The filler in the insoluble matter of the sample is photographed using an optical microscope, and the fiber length of the alumina fibers is measured using an image analysis device. The average fiber length (μm) is defined as the average value Lv of the fiber length of 100 alumina fibers, based on the volume of the fibers in the following formula (1), starting with the longest fiber. Lv=Σ(L×v) / Σv...Formula (1) Here, Σ represents a set, L represents the length of each alumina fiber, and v represents the volume of each alumina fiber.

5. The resin composition according to any one of claims 1 to 3, wherein the average fiber diameter of the alumina fibers according to method A (contour method) of JIS R 3420:2013 is 0.1 μm or more and 20 μm or less.

6. The resin composition according to any one of claims 1 to 3, wherein the content of the alumina fibers is 1.0% by mass or more and 40.0% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

7. The resin composition according to any one of claims 1 to 3, wherein the thermosetting resin includes an epoxy resin.

8. The resin composition according to claim 7, wherein the epoxy resin comprises one or more selected from the group consisting of phenol novolac type epoxy resin, cresol novolac type epoxy resin, and biphenyl type epoxy resin.

9. The resin composition according to any one of claims 1 to 3, wherein the content of the thermosetting resin is 1.0% by mass or more and 40.0% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

10. The resin composition according to any one of claims 1 to 3, further comprising a curing agent.

11. The resin composition according to claim 10, wherein the curing agent comprises a phenolic resin-based curing agent.

12. The resin composition according to claim 10, wherein the content of the curing agent is 1.0% by mass or more and 10.0% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

13. The resin composition according to any one of claims 1 to 3, further comprising an inorganic filler (excluding the alumina fibers).

14. The resin composition according to claim 13, wherein the inorganic filler comprises one or more selected from the group consisting of silica, alumina particles, kaolin, talc, clay, mica, rock wool, wollastonite, glass powder, glass flakes, glass beads, glass fibers, silicon carbide, silicon nitride, aluminum nitride, calcium carbonate, and calcium sulfate.

15. The resin composition according to claim 13, wherein the content of the inorganic filler is 50.0% by mass or more and 90.0% by mass or less, when the total solid content of the resin composition is considered to be 100% by mass.

16. A resin composition according to any one of claims 1 to 3, which is in the form of a powder, granules, or tablets.

17. A resin composition according to any one of claims 1 to 3, wherein the bending strength by the method described below (Method 2) is 10 MPa or more and 300 MPa or less. (Method 2) Using a transfer molding machine, the resin composition is injected under the conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a molded product with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The bending strength of the obtained molded product is measured in accordance with JIS K 6911:2006 at an ambient temperature of 25°C.

18. A resin composition according to any one of claims 1 to 3, wherein the flexural modulus of elasticity by the method described below (Method 3) is 1.0 GPa or more and 100.0 GPa or less. (Method 3) Using a transfer molding machine, the resin composition is injected under the conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a molded product with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The flexural modulus of the obtained molded product is measured in accordance with JIS K 6911:2006 at an ambient temperature of 25°C.

19. Storage modulus E' at 25°C according to the method (Method 4) described below. ２５ A resin composition according to any one of claims 1 to 3, wherein the pressure is 1.0 GPa or more and 100.0 GPa or less. (Method 4) Using a transfer molding machine, the resin composition was injected and molded under the conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of the obtained test specimen was measured at 25°C using a dynamic viscoelasticity analyzer in tensile mode and at a frequency of 10 Hz.

20. Storage modulus E' at 260°C according to the method (Method 5) below ２６０ The resin composition according to any one of claims 1 to 3, wherein the pressure is 0.1 GPa or more and 10.0 GPa or less. (Method 5) Using a transfer molding machine, the resin composition was injected and molded under the conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The storage modulus of the obtained test specimen was measured at 260°C using a dynamic viscoelasticity analyzer in tensile mode and at a frequency of 10 Hz.

21. The resin composition according to any one of claims 1 to 3, wherein the glass transition temperature according to the method (6) below is 70°C or more and 300°C or less. (Method 6) Using a transfer molding machine, the resin composition is injected and molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 180 seconds to obtain a test specimen with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The tanδ of the obtained test specimen is measured using a dynamic viscoelasticity analyzer under the conditions of a heating rate of 5°C / min, a frequency of 10 Hz, and a load of 800 g, and the temperature at the peak of tanδ is read as the glass transition temperature.

22. A resin composition according to any one of claims 1 to 3, which can be used for encapsulating electronic components.

23. A resin composition according to any one of claims 1 to 3, which can be used to seal the coils of a stator core.

24. A resin composition according to any one of claims 1 to 3, which can be used to fix a magnet in a hole in a rotor core.

25. The device comprises an electronic component and a sealing material for sealing the electronic component, An electronic device wherein the sealing material includes a cured product of the resin composition described in any one of claims 1 to 3.

26. It comprises a rotor core having a hole, a magnet in the hole, and a fixing material for fixing the magnet in the hole, A rotor wherein the fixing material includes a cured product made from the resin composition described in any one of claims 1 to 3.

27. A motor comprising the rotor described in claim 26.

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