Compound and bonded magnet

Abstract

Provided is a compound containing: magnetic particles; an epoxy resin; a phenoxy resin; and a resin composition containing a curing agent. Also provided is a bonded magnet containing: magnetic particles; an epoxy resin; a phenoxy resin; and a cured product of a resin composition containing a curing agent.

Description

Compound and bonded magnets

[0001] This disclosure relates to compound and bonded magnets.

[0002] Bonded magnets, which contain magnetic particles and resin, have an advantage over sintered magnets in terms of their greater freedom in shape. Thermosetting resins are the main resins used in bonded magnets. For example, Patent Document 1 discloses a method for manufacturing bonded magnets using epoxy resin and phenol novolac resin.

[0003] Patent No. 7298804

[0004] Depending on the environment in which bonded magnets are used, water resistance may be required. Therefore, one aspect of this disclosure is to provide a bonded magnet with excellent water resistance.

[0005] The inventors have discovered that by using phenoxy resin in addition to conventionally used epoxy resin as the resin in bonded magnets, water resistance can be improved.

[0006] This disclosure includes the following aspects: [1] A compound comprising magnetic particles and a resin composition comprising an epoxy resin, a phenoxy resin, and a curing agent. [2] The compound according to [1], wherein the weight-average molecular weight of the phenoxy resin is 10,000 or more. [3] The compound according to [1] or [2], wherein the resin composition further comprises a phenolic resin. [4] The compound according to [3], wherein the phenoxy resin content is 30 parts by mass or more per 100 parts by mass of the total mass of the epoxy resin and the phenolic resin. [5] The compound according to [3] or [4], wherein the curing agent comprises an imidazole compound. [6] The compound according to any one of [1] to [5], wherein the magnetic particles comprise an Sm-Fe-N permanent magnet. [7] A bonded magnet comprising magnetic particles and a cured product of a resin composition comprising an epoxy resin, a phenoxy resin, and a curing agent. [8] The bonded magnet according to [7], wherein the weight-average molecular weight of the phenoxy resin is 10,000 or more. [9] The bonded magnet according to [7] or [8], wherein the resin composition further comprises a phenolic resin.

[10] The bonded magnet according to [9], wherein the phenoxy resin content is 30 parts by mass or more per 100 parts by mass of the total mass of the epoxy resin and the phenolic resin.

[11] The bonded magnet according to [9] or

[10] , wherein the curing agent comprises an imidazole compound.

[12] The bonded magnet according to any one of [7] to

[11] , wherein the magnetic particles comprise an Sm-Fe-N permanent magnet.

[0007] According to one aspect of this disclosure, it is possible to provide a bonded magnet with excellent water resistance.

[0008] This is a schematic diagram showing a cross-section of particles constituting a compound according to one embodiment of the present disclosure. This is a schematic diagram showing a cross-section of a bonded magnet according to one embodiment of the present disclosure.

[0009] The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below.

[0010] One embodiment of the present disclosure is a compound containing magnetic particles and a resin composition comprising an epoxy resin, a phenoxy resin, and a curing agent.

[0011] The compound may be in powder, tablet, or paste form. The magnetic particles in the compound may be coated with a resin composition. The compound may also be a mixture of magnetic particles and a solid resin composition.

[0012] Figure 1 is a schematic diagram showing a cross-section of particles constituting a compound according to one embodiment of the present disclosure. The particles 1 constituting the compound include magnetic particles 10 and a resin composition 12. In Figure 1, the magnetic particles 10 are coated with the resin composition 12.

[0013] The magnetic particles may be composed of permanent magnets. The permanent magnets may be samarium-cobalt (Sm-Co) permanent magnets, neodymium-iron-boron (Nd-Fe-B) permanent magnets, samarium-iron-nitrogen (Sm-Fe-N) permanent magnets, iron-cobalt (Fe-Co) permanent magnets, or Al-Ni-Co permanent magnets (alnico magnets). Preferably, the magnetic particles include samarium-iron-nitrogen (Sm-Fe-N) permanent magnets.

[0014] The magnetic particles may be composed of a soft magnetic material. The soft magnetic material may contain at least one metal selected from the group consisting of pure iron and iron-containing alloys. The iron-containing alloy may be at least one selected from the group consisting of, for example, Fe-Cr alloys (stainless steel), Fe-Ni-Cr alloys (stainless steel), Fe-Si alloys, Fe-Si-Al alloys (Sendust), Fe-Ni alloys (Permalloy), Fe-Cu-Ni alloys (Permalloy), Fe-Cr-Si alloys (electromagnetic stainless steel), and Fe-Ni-Mn-C alloys (Invar). The soft magnetic material may be amorphous. The soft magnetic material may be an Fe amorphous alloy. The magnetic particles composed of the soft magnetic material may be composed of amorphous iron or carbonyl iron.

[0015] Magnetic particles may contain multiple types of metallic elements. In addition to the above elements, magnetic particles may further contain at least one element selected from the group consisting of base metal elements, noble metal elements, transition metal elements, and rare earth elements. Magnetic particles may further contain at least one element selected from the group consisting of copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), oxygen (O), beryllium (Be), phosphorus (P), boron (B), and silicon (Si).

[0016] The average particle size of the magnetic particles may be 0.1 μm or more, 1 μm or more, or 2 μm or more, and may be 30 μm or less, 20 μm or less, or 10 μm or less.

[0017] The average particle size of magnetic particles is defined as the particle size (D50) at which the cumulative volume distribution curve reaches 50% when plotted from the smallest diameter side in the particle size distribution. The average particle size is measured using a laser diffraction particle size analyzer.

[0018] The compound may contain one type of magnetic particle, or multiple types of magnetic particles. The compound may contain multiple types of magnetic particles that differ in average particle size. The shape of the magnetic particles is not particularly limited. The magnetic particles may be, for example, spherical, flattened, or needle-shaped.

[0019] Magnetic particles may be surface-treated with one or more surface treatment agents. Examples of surface treatment agents used include silane coupling agents, titanate coupling agents, aluminate coupling agents, and zirconate coupling agents.

[0020] Examples of silane coupling agents include 8-methacryloxyoctyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0021] The magnetic particle content may be 70% by mass or more, or 80% by mass or more, and 96% by mass or less, or 95.5% by mass or less, based on the total amount of the compound.

[0022] Examples of epoxy resins include biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur atom-containing epoxy resins, novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins, copolymer epoxy resins of naphthols and phenols, epoxidized aralkyl-type phenolic resins, bisphenol-type epoxy resins, glycidyl ether-type epoxy resins of alcohols, cyclopentadiene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl-type or methylglycidyl-type epoxy resins, alicyclic epoxy resins, orthocresol novolac-type epoxy resins, hydroquinone-type epoxy resins, thioether-type epoxy resins, trimethylolpropane-type epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid.

[0023] The epoxy equivalent of the epoxy resin may be 100 g / eq or more, 130 g / eq or more, 150 g / eq or more, 200 g / eq or more, or 400 g / eq or more. From the viewpoint of further improving the water resistance of the bonded magnet, the epoxy equivalent of the epoxy resin may be 700 g / eq or less, 600 g / eq or less, 550 g / eq or less, 500 g / eq or less, 250 g / eq or less, or 200 g / eq or less. The epoxy equivalent is the mass of epoxy resin containing one equivalent of epoxy groups. The epoxy equivalent can be measured in accordance with JIS K7236.

[0024] The epoxy resin content may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, 41% by mass or more, 43% by mass or more, 45% by mass or more, 60% by mass or more, or 63% by mass or more, based on the total amount of the resin composition. From the viewpoint of further improving the water resistance of the bonded magnet, the epoxy resin content may be 80% by mass or less, 70% by mass or less, based on the total amount of the resin composition, and preferably 63% by mass or less, 55% by mass or less, 50% by mass or less, 45% by mass or less, 43% by mass or less, or 41% by mass or less.

[0025] The resin composition includes a phenoxy resin to improve the water resistance of the bonded magnet. Examples of phenoxy resins include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, and bisphenol S type phenoxy resin.

[0026] The weight-average molecular weight of the phenoxy resin may be 10,000 or more, 20,000 or more, 30,000 or more, or 50,000 or more, and may be 200,000 or less, 100,000 or less, or 80,000 or less.

[0027] Note that the weight-average molecular weight is measured using GPC (Gel Permeation Chromatography) and converted using a calibration curve based on standard polystyrene. An example of the measurement conditions for weight-average molecular weight is shown below.

[0028] Instrument name: HLC-8320 (manufactured by Tosoh Corporation) Column: TSKgel SuperMultipore HZ-M (3 tubes) (manufactured by Tosoh Corporation) Detector: HLC-8320 (manufactured by Tosoh Corporation) RI Column temperature: 40°C Eluent: A solvent in which the target of measurement dissolves can be selected. Examples of solvents include tetrahydrofuran. Flow rate: 0.35 mL / min Standard substance: Polystyrene

[0029] The phenoxy resin content may be 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 26% by mass or more, 30% by mass or more, 33% by mass or more, or 36% by mass or more, based on the total amount of the resin composition, from the viewpoint of further improving the water resistance of the bonded magnet. The phenoxy resin content may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, 33% by mass or less, 30% by mass or less, or 25% by mass or less, based on the total amount of the resin composition.

[0030] If the resin composition further contains a phenolic resin (details will be described later), the phenoxy resin content may be 10 parts by mass or more, 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 45 parts by mass or more, 50 parts by mass or more, or 55 parts by mass or more, based on 100 parts by mass of the total mass of the epoxy resin and the phenolic resin. The phenoxy resin content may be 80 parts by mass or less, 70 parts by mass or less, 65 parts by mass or less, 60 parts by mass or less, 55 parts by mass or less, 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, or 35 parts by mass or less, based on 100 parts by mass of the total mass of the epoxy resin and the phenolic resin.

[0031] The resin composition contains a curing agent. The curing agent may include imidazole compounds, hydrazide compounds, boron trifluoride-amine complexes, sulfonium salts, amineimides, polyamine salts, dicyandiamides, etc. From the viewpoint of further improving the curing rate of the resin composition, the curing agent preferably contains an imidazole compound. Examples of imidazole compounds include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole (4-methyl-2-phenylimidazole), 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-aminopropyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-cyanoethyl-2-phenylimidazole, etc.

[0032] The curing agent may be a latent curing agent. A latent curing agent is, for example, a microcapsule-type curing agent in which the above-mentioned curing agent is coated with a coating layer. Examples of materials constituting the coating layer include polymers such as polyurethane and polyester, thin metal films such as nickel and copper, and calcium silicate.

[0033] The curing agent content may be 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.39% by mass or more, 0.45% by mass or more, 0.56% by mass or more, or 1.5% by mass or more, based on the total amount of the resin composition, from the viewpoint of further improving the curing speed of the resin composition. The curing agent content may be 4% by mass or less, 3% by mass or less, 2.5% by mass or less, 1% by mass or less, 0.8% by mass or less, 0.55% by mass or less, 0.45% by mass or less, or 0.38% by mass or less, based on the total amount of the resin composition.

[0034] The resin composition may further contain a phenolic resin to further improve the heat resistance (mechanical strength at high temperatures) of the bonded magnet. In the compound according to this embodiment, the resin composition may further contain a phenolic resin, and the curing agent may contain an imidazole compound.

[0035] Examples of phenolic resins include aralkyl phenolic resins, dicyclopentadiene phenolic resins, salicylaldehyde phenolic resins, novolac phenolic resins, copolymer phenolic resins of benzaldehyde phenol and aralkyl phenolic resins, paraxylylene and / or metaxylylene-modified phenolic resins, melamine-modified phenolic resins, terpene-modified phenolic resins, dicyclopentadiene-modified naphthol resins, cyclopentadiene-modified phenolic resins, polycyclic aromatic ring-modified phenolic resins, biphenyl-modified phenolic resins, triphenylmethane-modified phenolic resins, and the like. In this specification, resins that fall under both epoxy resins and phenolic resins are classified as epoxy resins.

[0036] The hydroxyl equivalent weight of the phenolic resin may be 30 g / eq or more, 50 g / eq or more, or 70 g / eq or more, and may be 300 g / eq or less, 200 g / eq or less, or 150 g / eq or less. The hydroxyl equivalent weight is the mass of the resin containing 1 equivalent of hydroxyl groups. The hydroxyl equivalent weight can be measured by neutral titration (in accordance with JIS K0070:1992).

[0037] The weight average molecular weight of the phenolic resin may be 100 or more, 200 or more, 300 or more, or 400 or more, and may be 3000 or less, 2000 or less, or 1000 or less. The method for measuring the weight average molecular weight of the phenolic resin may be the same as the method for measuring the weight average molecular weight of the above-mentioned phenoxy resin.

[0038] From the perspective of further improving the heat resistance (mechanical strength at high temperatures) of the bonded magnet or further improving the water resistance, the content of the phenolic resin may be 5% by mass or more, 10% by mass or more, 13% by mass or more, 20% by mass or more, 22% by mass or more, 23% by mass or more, or 24% by mass or more based on the total amount of the resin composition. The content of the phenolic resin may be 40% by mass or less, 35% by mass or less, 30% by mass or less, 24% by mass or less, 23% by mass or less, 22% by mass or less, or 18% by mass or less based on the total amount of the resin composition.

[0039] The resin composition may contain other resins other than epoxy resin, phenoxy resin and phenolic resin. Examples of other resins include bismaleimide resin, polyimide resin, polyamideimide resin, acrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, etc. The content of other resins may be 0.1% by mass or more and 1% by mass or less based on the total amount of the resin composition.

[0040] The resin composition may contain additives. Examples of additives include curing accelerators (curing catalysts), flame retardants, waxes (lubricants), and organic solvents.

[0041] Examples of organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, ethyl acetate, and xylene. One or more organic solvents may be used. The content of the organic solvent may be 0.1% by mass or more, and 1% by mass or less, based on the total amount of the resin composition.

[0042] The content of the resin composition may be 3.6% by mass or more, or 4% by mass or more, and may be 10% by mass or less, or 8% by mass or less, based on the total amount of the compound.

[0043] The content of the resin composition may be 4 parts by mass or more, or 4.2 parts by mass or more, and 10 parts by mass or less, or 7 parts by mass or less, per 100 parts by mass of magnetic particles.

[0044] Next, a method for manufacturing the compound described above will be explained. The compound may be obtained by a manufacturing method comprising a first step of dispersing magnetic particles and a resin composition in an organic solvent, and a second step of removing the organic solvent after the first step. The compound may also be obtained by a manufacturing method comprising a first step, a second step, and a third step of pulverizing the solid obtained after the first and second steps.

[0045] Although organic solvents are used in the compound manufacturing method described above, the compound may be manufactured without using organic solvents. In other words, the compound may be obtained by a process of mixing magnetic particles and a resin composition without using organic solvents. The magnetic particles and the resin composition may be mixed in a sealed container.

[0046] The compound described above is suitably used in the manufacture of bonded magnets. A method for manufacturing a bonded magnet according to one embodiment may include a step of molding the compound (molding step). This step may be a step of molding the compound by compression. When compressing, for example, in this step the compound placed in the mold is compressed. The molding pressure may be 500 MPa or more, 700 MPa or more, or 980 MPa or more, and may be 2500 MPa or less, or 2000 MPa or less.

[0047] The molding process may be carried out while heating. The heating temperature may be 80°C or higher, or 120°C or higher, and 250°C or lower, or 170°C or lower. The heating time may be 5 minutes or more, or 7 minutes or more, and 4 hours or less, or 1 hour or less.

[0048] The molding process may be carried out while applying a magnetic field. Examples of the applied magnetic field include a static magnetic field (a continuous, constant magnetic field) and a pulsed magnetic field (a pulsed magnetic field). The strength of the static magnetic field may be 0.5 T or more, 1 T or more, or 2 T or more, and may be 3 T or less, or 2.5 T or less. The strength of the pulsed magnetic field may be 4 T or more, or 8 T or more, and may be 20 T or less, or 12 T or less. The number of times the pulsed magnetic field is applied may be one or two or more times.

[0049] A method for manufacturing a bonded magnet according to one embodiment may further include a step of cooling the bonded magnet after the molding step (cooling step). The cooling temperature may be 0°C or higher, or 5°C or higher, and 30°C or lower, or 25°C or lower. The cooling method may be natural cooling.

[0050] A method for manufacturing a bonded magnet according to one embodiment may further include a step of demagnetizing the bonded magnet (demagnetization step) after performing a molding step while applying a magnetic field. The demagnetization step may be performed after the cooling step or simultaneously with the cooling step. The demagnetization step may be performed by applying a magnetic field in the opposite direction to the magnetic field applied in the molding step. The details of the magnetic field applied in the demagnetization step may be the same as the details of the magnetic field applied in the molding step described above.

[0051] A method for manufacturing a bonded magnet according to one embodiment may further include a step of curing the epoxy resin in the obtained molded body (thermosetting step) after the molding step, cooling step, or demagnetization step. As the thermosetting of the epoxy resin progresses, the bulk density, mechanical strength, and residual magnetic flux density of the bonded magnet tend to increase further.

[0052] The method for manufacturing bonded magnets according to this embodiment may further include a step of magnetizing the bonded magnets (magnetization step) after the demagnetization step, or after the demagnetization step and the thermosetting step. The details of the magnetic field applied in the magnetization step may be the same as the details of the magnetic field applied in the molding step described above.

[0053] One embodiment of the present disclosure is a bonded magnet containing a cured product of the compound described above. In other words, one embodiment of the present disclosure is a bonded magnet containing magnetic particles and a cured product of the resin composition described above, which includes an epoxy resin, a phenoxy resin, and a curing agent. Figure 2 is a schematic diagram showing a cross-section of a bonded magnet 2 according to one embodiment. The bonded magnet 2 contains magnetic particles 10 and a cured product 22 of the resin composition.

[0054] The bulk density of the bonded magnets is set at 6 g / cm³ from the viewpoint of further increasing the residual magnetic flux density or further increasing the mechanical strength. ３ More than 6.02 g / cm³ ３ The above is sufficient. The bulk density of the bonded magnet is 10 g / cm³. ３ The following, or 8 g / cm³ ３ The following is acceptable:

[0055] The magnetization direction of each magnetic particle in the bonded magnet may be random or oriented. The bonded magnet may be isotropic or anisotropic.

[0056] The present disclosure will be described in more detail below based on the examples. The examples described below are representative examples of the present disclosure and the present disclosure is not limited to these examples.

[0057] (Example 1) A resin solution was obtained by mixing 100 parts by mass of epoxy resin 1 (product name "YX4000", manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 192 g / eq), 50 parts by mass of phenoxy resin (product name "YP-50", manufactured by Nippon Steel Chemical & Material Co., Ltd., weight-average molecular weight: 70000), 3 parts by mass of curing agent 1 (polyurethane-based latent curing agent, product name "HX3088", manufactured by Asahi Kasei Corporation), and an organic solvent (a mixture of toluene and ethyl acetate). Sm was added to the resin solution. ２ Fe１７ N ３ 2,860 parts by mass of an Sm—Fe—N-based alloy powder (spherical magnet powder, average particle size 3 μm) containing a main phase composed of N was added and dispersed. After dispersion, the resin solution was dried at 60° C. for 2 hours to obtain a compound.

[0058] Approximately 2 g of the obtained compound was supplied into the mold of a molding device. The capacity of the mold was 7 mm in length, 7 mm in width, and 7 mm in height. As the molding device, a hydraulic press device (product name “TM-MPH10525-10A2TM type”, manufactured by Tamagawa Seisakusho Co., Ltd.) was used, and heat compression was performed under the conditions of a heating temperature of 150° C., a pressure of 1,800 MPa, and a compression time of 10 minutes. After heat compression, the mold was cooled to room temperature to obtain a bonded magnet. The bulk density of the bonded magnet was 6.05 g / cm ３ It was.

[0059] (Example 2) Phenol resin (product name “HP-850”, manufactured by Resonaak Co., Ltd., hydroxyl equivalent: 108 g / eq, weight average molecular weight: 560) was further mixed, and instead of curing agent 1, curing agent 2 (2-ethyl-4-methylimidazole, product name “2E4MZ”, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was mixed. A bonded magnet was obtained in the same manner as in Example 1 except that the mixing amounts of the respective components were changed to the mixing amounts described in Table 1. The bulk density of the bonded magnet was 6.03 g / cm ３ It was.

[0060] (Examples 3, 4, 5) Instead of epoxy resin 1, epoxy resin 2 (product name “HP-4770”, manufactured by DIC Corporation, epoxy equivalent: 204 g / eq) was mixed. A bonded magnet was obtained in the same manner as in Example 2 except that the mixing amounts of the respective components were changed to the mixing amounts described in Table 1. The bulk densities of the bonded magnets were 6.05 g / cm ３ (Example 3), 6.04 g / cm ３ (Example 4), 6.03 g / cm ３ (Example 5), respectively.

[0061] (Example 6) A bonded magnet was obtained in the same manner as in Example 2, except that epoxy resin 3 (product name "EP1050", manufactured by DIC Corporation, epoxy equivalent: 470 g / eq) was mixed in place of epoxy resin 1, and the mixing amounts of each component were changed to the mixing amounts shown in Table 1. The bulk density of the bonded magnet was 6.04 g / cm³. ３ That was the case.

[0062] (Comparative Example 1) A bonded magnet was obtained in the same manner as in Example 1, except that phenoxy resin was not mixed. The bulk density of the bonded magnet was 6.01 g / cm³. ３ That was the case.

[0063] (Comparative Example 2) A bonded magnet was obtained in the same manner as in Example 2, except that phenoxy resin was not mixed. The bulk density of the bonded magnet was 6.00 g / cm³. ３ That was the case.

[0064] (Comparative Example 3) A bonded magnet was obtained in the same manner as in Example 3, except that phenoxy resin was not mixed. The bulk density of the bonded magnet was 6.01 g / cm³. ３ That was the case.

[0065] (Comparative Example 4) A bonded magnet was obtained in the same manner as in Example 6, except that phenoxy resin was not mixed. The bulk density of the bonded magnet was 6.00 g / cm³. ３ That was the case.

[0066] <Crushing Strength> The bonded magnets of Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to compression pressure from the height direction using a universal compression tester (Shimadzu Corporation, AG-10TBR) at a temperature of 25°C. The crushing strength (MPa) was calculated from the maximum value of the compression pressure at which the bonded magnet broke. The results are shown in Table 1.

[0067] <Water Resistance Test> Bonded magnets of Examples 1-6 and Comparative Examples 1-4 were immersed in water at 25°C for 3 days. After immersion, the crushing strength of each bonded magnet was measured using the same method as described above, and the percentage decrease in crushing strength of the bonded magnet due to immersion was calculated. The results are shown in Table 1. The percentage decrease was calculated using the following formula: Percentage decrease (%) = (Crushing strength before immersion - Crushing strength after immersion) / (Crushing strength before immersion) × 100

[0068]

[0069] 1...Particles constituting the compound, 2...Bonded magnet, 10...Magnetic particles, 12...Resin composition, 22...Cured product of the resin composition.

Claims

1. A compound containing magnetic particles and a resin composition comprising epoxy resin, phenoxy resin, and a curing agent.

2. The compound according to claim 1, wherein the weight-average molecular weight of the phenoxy resin is 10,000 or more.

3. The compound according to claim 1, wherein the resin composition further comprises a phenolic resin.

4. The compound according to claim 3, wherein the content of the phenoxy resin is 30 parts by mass or more with respect to 100 parts by mass of the total mass of the epoxy resin and the phenolic resin.

5. The compound according to claim 3, wherein the curing agent comprises an imidazole compound.

6. The compound according to claim 1, wherein the magnetic particles include an Sm-Fe-N permanent magnet.

7. A bonded magnet containing magnetic particles and a cured product of a resin composition comprising epoxy resin, phenoxy resin, and a curing agent.

8. The bonded magnet according to claim 7, wherein the weight-average molecular weight of the phenoxy resin is 10,000 or more.

9. The bonded magnet according to claim 7, wherein the resin composition further comprises a phenolic resin.

10. The bonded magnet according to claim 9, wherein the content of the phenoxy resin is 30 parts by mass or more with respect to 100 parts by mass of the total mass of the epoxy resin and the phenolic resin.

11. The bonded magnet according to claim 9, wherein the curing agent comprises an imidazole compound.

12. The bonded magnet according to claim 7, wherein the magnetic particles include an Sm-Fe-N permanent magnet.

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