Mixture

Abstract

Provided is a mixture which has a long usable time in a manufacturing process, has little change in characteristics due to heating during bonded magnet molding, and has high mechanical strength even when a thermosetting resin is subjected to a curing reaction under low temperature conditions. A mixture containing an epoxy resin (A), metal element-containing particles (C), and a curing agent (D) having an imidazole structure, the curing agent (D) having an imidazole structure comprising a compound represented by formula (1) and / or a compound represented by formula (2). R1, R2, X, Y, Z, m and n are as described in the specification.

Description

Technical Field

[0001] This invention relates to mixtures. Background Technology

[0002] A molded body obtained by mixing magnetic particles with binder materials such as resin and processing them into a specified shape is called a bonded magnet. Because bonded magnets contain resin, they have a high degree of shape freedom and superior formability compared to sintered magnets. Therefore, their applications are expanding in motors used in automobiles, general household appliances, communication and audio equipment, medical equipment, and general industrial equipment.

[0003] On the other hand, for these motors, it is predicted that the motor speed will increase when high output is required, and there is a tendency to require the bonded magnets subjected to strong centrifugal forces to have high mechanical strength to suppress cracking and breakage.

[0004] Patent Document 1 discloses a resin mixture for bonding magnets, which contains epoxy resin, curing agent, curing accelerator and magnetic powder. The accelerator has borane structure and borate structure, thereby maintaining excellent stability and mechanical strength.

[0005] Patent document 2 discloses a method for manufacturing a bonded magnet. In the method for manufacturing a bonded magnet containing epoxy resin, curing agent, curing accelerator and magnet powder and using a solvent, the accelerator and the solvent meet the specified composition, thereby achieving excellent mechanical strength and a long usable time in the manufacturing process.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 6606908

[0009] Patent Document 2: Japanese Patent No. 6198633 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] The molding methods for bonded magnets are divided into compression molding and injection molding. They are often formed by applying heat and / or pressure to a composite material "compound" obtained by mixing magnetic particles and resin components as binders. Compression molding mixtures use thermosetting resins as resin components, resulting in excellent heat resistance. However, the curing reaction of the resin components occurs during mixture preparation and bonded magnet molding, often causing problems with usable time and reduced properties of the bonded magnets during the manufacturing process.

[0012] In addition, in compression molding, heating is required to promote the curing reaction of thermosetting resin. However, the magnetic particles in the mixture are not heat-resistant. Under heating conditions, the surface of the magnetic particles is oxidized, which can easily lead to a decrease in magnetic properties.

[0013] Therefore, there is a requirement for a mixture for bonding magnets that has high mechanical strength capable of suppressing the cracking of the bonded magnet, even when the thermosetting resin is reacted under low temperature conditions (e.g., below 150°C).

[0014] In contrast, although the mixture for bonding magnets containing curing accelerators with borane and borate structures, as described in Patent Document 1 above, has a certain effect on reducing the usable time and characteristics of the bonded magnets in the manufacturing process, there is room for improvement in mechanical strength when the thermosetting resin is cured at a lower temperature.

[0015] Furthermore, although the adhesive magnet mixture produced by the manufacturing method of satisfying the specified composition of accelerator and solvent as described in Patent Document 2 above has a certain effect on reducing the usable time and the characteristics of the adhesive magnet in the manufacturing process, there is room for improvement in mechanical strength when the thermosetting resin is cured at a lower temperature.

[0016] The problem to be solved by the present invention is to provide a bonded magnet mixture that has a long usable time in the manufacturing process, minimal changes in properties caused by heating during the molding of the bonded magnet, and high mechanical strength when the thermosetting resin is cured at low temperature.

[0017] Solution for solving the problem

[0018] In order to solve the above-mentioned problems, the inventors have repeatedly conducted in-depth research and found that by containing epoxy resin, curing agent, magnetic particles and curing accelerator, and wherein the curing accelerator meets the specified composition, the problems of the prior art can be solved, and thus the present invention is completed.

[0019] That is, the present invention includes the following methods.

[0020] <1> A compound comprising an epoxy resin (A), metal-containing particles (C), and a curing agent (D) having an imidazole structure.

[0021] The curing agent (D) having an imidazole structure comprises a compound represented by formula (1) and / or a compound represented by formula (2).

[0022]

[0023] In formulas (1) and (2), R1 and R2 are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, halogen atom, alkyl group with 1 to 20 carbon atoms that may have substituents, and cycloalkyl group with 6 to 20 carbon atoms that may have substituents. R1 and R2 may be the same or different, and R1 and R2 may be bonded together to form a fused ring that is not aromatic.

[0024] X is any one of the following groups: hydrogen atom, alkyl group with 1 to 20 carbon atoms that have substituted groups, alkenyl group with 2 to 20 carbon atoms that have substituted groups, aralkyl group with 7 to 20 carbon atoms that have substituted groups, and heteroarylalkyl group with 4 to 20 carbon atoms that have substituted groups.

[0025] Y and Z are each independently selected from the group consisting of hydrogen atom, halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group with 1 to 20 carbon atoms optionally having a substituent, alkoxy group with 1 to 20 carbon atoms optionally having a substituent, alkenyl group with 2 to 20 carbon atoms optionally having a substituent, aryl group with 6 to 20 carbon atoms optionally having a substituent, aryloxy group with 6 to 20 carbon atoms optionally having a substituent, and acyl group with 1 to 20 carbon atoms optionally having a substituent. Y and Z may be the same or different, and two or more Y groups or two or more Z groups may be optionally bonded to form a monocyclic or fused ring. m and n are each independently an integer from 1 to 4.

[0026] <2> according to <1> The mixture, wherein, in the curing agent (D) having an imidazole structure,

[0027] Y and Z are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, alkoxy group with 1 to 20 carbon atoms without substituents, alkyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, alkoxy group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, aryl group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, aryloxy group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, and acyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents.

[0028] <3> according to <1> or <2> The mixture, wherein, in the curing agent (D) having an imidazole structure,

[0029] The compound represented by formula (1) is any one selected from the group consisting of 2-(2-hydroxyphenyl)imidazolium, 2-(2-hydroxyphenyl)-4-methylimidazolium, 2-(2-hydroxyphenyl)-5-methylimidazolium, 4-ethyl-(2-hydroxyphenyl)-5-methylimidazolium, (2-hydroxyphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxyphenyl)-5-methylimidazolium, 2-(2-hydroxy-3-methoxyphenyl)imidazolium and 2-(2-hydroxy-5-methoxyphenyl)imidazolium;

[0030] And / or,

[0031] The compound represented by formula (2) is any one selected from the group consisting of 2-(2-hydroxyphenyl)benzimidazole, 2-(2-hydroxy-3-methoxyphenyl)benzimidazole, 2-(2-hydroxy-5-methoxyphenyl)benzimidazole, 2-(1-hydroxynaphth-2-yl)benzimidazole, 2-(2-hydroxynaphth-1-yl)benzimidazole and 2-(2-hydroxyphenyl)benzimidazole-6-carboxylic acid.

[0032] <4> according to <1> or <2> The mixture further comprises a curing agent (B) that is different from a curing agent having an imidazole structure.

[0033] <5> according to <4> The mixture, wherein the curing agent (B) different from the curing agent having an imidazole structure comprises a curing agent that is solid at room temperature (25°C), and the content of the curing agent that is solid at room temperature (25°C) is 50% by mass or more relative to the total amount of the curing agent.

[0034] <6> according to <1> or <2> The mixture wherein the metal-containing particles (C) are magnetic particles.

[0035] <7> according to <6> The mixture, wherein the magnetic particles are rare earth magnetic particles.

[0036] <8> according to <6> The mixture wherein the content of the magnetic particles is 70% by mass or more and 99.5% by mass or less relative to the total mass of the mixture.

[0037] <9> according to <6> The mixture wherein the magnetic particles have a specific surface area of ​​0.005 m². 2 / g or more and 5.0m 2 / g or less.

[0038] <10> according to <6> In the mixture, the content (mass%) of the magnetic particles relative to the total mass of the mixture is defined as (X), and the specific surface area of ​​the magnetic particles is defined as (Y).

[0039] When the content (mass%) of the curing agent (D) having an imidazole structure relative to the total mass of the mixture is set as (Z),

[0040] (X), (Y), and (Z) satisfy the following equation (γ),

[0041] 0.000010≤(Z) / (X)×(Y)≤0.30…(γ)

[0042] <11> according to <1> The mixture, wherein the epoxy resin (A) comprises a portion of the structure represented by the following formula (A1).

[0043]

[0044] (In formula (A1), R1 to R3 are each independently a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a heteroatom, or a substituent containing a halogen atom. At least one of R1 to R3 contains a reactive group that reacts with the curing agent (D) having the imidazole structure. R1 to R3 may be the same as or different from each other.)

[0045] <12> according to <1> The mixture, wherein the epoxy resin (A) comprises a portion of the structure represented by the following formula (A2).

[0046]

[0047] (In formula (A2), R) 1 R 2 It is an alkylene group having 1 to 12 carbon atoms, where m and n are each an independent integer greater than or equal to 1. G 1 and G 2 It is selected from the group consisting of hydrogen atoms, alkyl groups, aromatic groups, substituents containing heteroatoms, and substituents containing halogen atoms. G 1 and G 2 (They can choose to be the same or different from each other.)

[0048] <13> according to <1> or <2> The mixture, wherein the epoxy resin (A) comprises an epoxy resin that is solid at room temperature (25°C),

[0049] The content of the epoxy resin that is solid at room temperature (25°C) is 50% by mass or more relative to the total amount of epoxy resin.

[0050] <14> according to <1> or <2> The mixture further comprises a compound (E) represented by the following formula (3).

[0051]

[0052] In formula (3), R1 to R8 are each independently selected from the group consisting of hydrogen, alkyl, aromatic groups, substituents containing heteroatoms, and substituents containing halogen atoms. R1 to R8 may be the same or different. Furthermore, at least two of R4 to R8 may be selected to form a ring and form a fused ring with the adjacent benzene ring.

[0053] <15> A varnish comprising an epoxy resin (A), a curing agent (D) having an imidazole structure, a curing agent (B) different from the curing agent having an imidazole structure, and an organic solvent (G).

[0054] The curing agent (D) having an imidazole structure comprises a compound represented by formula (1) and / or a compound represented by formula (2).

[0055]

[0056] In formulas (1) and (2), R1 and R2 are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, halogen atom, alkyl group with 1 to 20 carbon atoms that may have substituents, and cycloalkyl group with 6 to 20 carbon atoms that may have substituents. R1 and R2 may be the same or different, and R1 and R2 may be bonded together to form a fused ring that is not aromatic.

[0057] X is any one of the following groups: hydrogen atom, alkyl group with 1 to 20 carbon atoms that have substituted groups, alkenyl group with 2 to 20 carbon atoms that have substituted groups, aralkyl group with 7 to 20 carbon atoms that have substituted groups, and heteroarylalkyl group with 4 to 20 carbon atoms that have substituted groups.

[0058] Y and Z are each independently selected from the group consisting of hydrogen atom, halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group with 1 to 20 carbon atoms optionally having a substituent, alkoxy group with 1 to 20 carbon atoms optionally having a substituent, alkenyl group with 2 to 20 carbon atoms optionally having a substituent, aryl group with 6 to 20 carbon atoms optionally having a substituent, aryloxy group with 6 to 20 carbon atoms optionally having a substituent, and acyl group with 1 to 20 carbon atoms optionally having a substituent. Y and Z may be the same or different, and two or more Y groups or two or more Z groups may be optionally bonded to form a monocyclic or fused ring. m and n are each independently an integer from 1 to 4.

[0059] <16> A type of bonded magnet, which is used to make <1> ~ <16> The mixture described in any one of the above is formed and cured.

[0060] <17> A motor comprising <16> The aforementioned bonded magnet.

[0061] The effects of the invention

[0062] According to the present invention, a mixture can be provided that has a long usable time in the manufacturing process, has minimal changes in properties due to heating during the molding of bonded magnets, and has high mechanical strength when the thermosetting resin is cured at low temperatures. Detailed Implementation

[0063] Hereinafter, a detailed description will be given of the method for carrying out the present invention (hereinafter referred to as "this embodiment").

[0064] It should be noted that the following embodiments are illustrative of the present invention, and the present invention is not limited to the following embodiments. The present invention can be appropriately modified and implemented within its scope.

[0065] In this embodiment, the numerical range represented by “~” refers to the range in which the values ​​recorded before and after “~” are respectively the minimum and maximum values.

[0066] In the numerical ranges described in this embodiment, the upper or lower limit value recorded in a certain numerical range can be replaced with the upper or lower limit value of other numerical ranges described in different stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value recorded in a certain numerical range can be replaced with the value shown in the embodiment.

[0067] In this embodiment, a combination of two or more preferred methods is a more preferred method.

[0068] In this embodiment, when there are multiple substances equivalent to each component, unless otherwise specified, the amount of each component refers to the total amount of the multiple substances.

[0069] Bonded Magnet Mixture

[0070] The mixture in this embodiment comprises epoxy resin (A), metal-containing particles (C), and curing agent (D).

[0071] The mixture of epoxy resin (A) and curing agent (D) (hereinafter referred to as the "resin composition") undergoes a curing reaction during heat treatment, forming a three-dimensional cross-link around the metal element particles (C), thus enabling the bonded magnet cured product to exhibit high mechanical strength.

[0072] <Epoxy Resin (A)>

[0073] The mixture in this embodiment contains epoxy resin.

[0074] As for epoxy resins, although not limited to the following, examples include biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-containing epoxy resins, phenolic varnish-type epoxy resins, cresol-phenolic varnish-type epoxy resins, biphenyl-phenolic varnish-type epoxy resins, and phenolic varnish-type epoxy resins such as naphthol-phenolic varnish-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins such as salicylaldehyde-phenolic varnish-type epoxy resins, copolymer epoxy resins of naphthol and phenol, epoxides of aralkyl-type phenolic resins, bisphenol-type epoxy resins, glycidyl ether-type epoxy resins of alcohols, and glycidyl ethers of p-xylene and / or m-xylene-modified phenolic resins. Epoxy resins include glycidyl ether type epoxy resins, terpene-modified phenolic resins, cyclopentadiene type epoxy resins, polycyclic aromatic ring-modified phenolic resins, naphthalene-containing phenolic resins, glycidyl ester type epoxy resins, glycidyl or methyl glycidyl type epoxy resins, alicyclic epoxy resins, halogenated phenolic varnish type epoxy resins, hydroquinone type epoxy resins, trimethylolpropane type epoxy resins, linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracetic acid or other peracids, epoxy resins containing a portion of the structure represented by formula (A1) below, and epoxy resins containing a portion of the structure represented by formula (A2) below. They can be used alone or in combination of two or more types.

[0075]

[0076] (In formula (A1), R1 to R3 are each independently a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a heteroatom, or a substituent containing a halogen atom, and at least one of R1 to R3 contains a reactive group that reacts with the curing agent (D) having the imidazole structure. R1 to R3 may be the same as or different from each other.)

[0077]

[0078] (In formula (A2), R) 1 R 2 It is an alkylene group having 1 to 12 carbon atoms, where m and n are each an independent integer greater than or equal to 1. G 1 and G 2 It is selected from the group consisting of hydrogen atoms, alkyl groups, aromatic groups, substituents containing heteroatoms, and substituents containing halogen atoms. G 1 and G 2 (They can choose to be the same or different from each other.)

[0079] From the viewpoint of improving the mechanical strength of bonded magnets, the epoxy resin preferably comprises at least one selected from the group consisting of biphenyl-type epoxy resin, o-cresol phenolic varnish-type epoxy resin, phenolic varnish-type epoxy resin, biphenyl phenolic varnish-type epoxy resin, salicylaldehyde phenolic varnish-type epoxy resin, naphthol phenolic varnish-type epoxy resin, epoxy resin comprising a portion of the structure represented by formula (A1) below, and epoxy resin comprising a portion of the structure represented by formula (A2) below. More preferably, it comprises at least one selected from the group consisting of epoxy resin comprising a portion of the structure represented by formula (A1) below and epoxy resin comprising a portion of the structure represented by formula (A2) below.

[0080]

[0081] (In formula (A1), R1 to R3 are each independently a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a heteroatom, or a substituent containing a halogen atom, and at least one of R1 to R3 contains a reactive group that reacts with the curing agent (D) having the imidazole structure. R1 to R3 may be the same as or different from each other.)

[0082]

[0083] (In formula (A2), R) 1 R 2 It is an alkylene group having 1 to 12 carbon atoms, where m and n are each an independent integer greater than or equal to 1. G 1 and G 2 It is selected from the group consisting of hydrogen atoms, alkyl groups, aromatic groups, substituents containing heteroatoms, and substituents containing halogen atoms. G 1 and G 2 (They can choose to be the same or different from each other.)

[0084] R 1 and R 2 The alkylene group having 1 to 12 carbon atoms can be either chain-like or branched. The number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 6. Examples of alkylene groups having 1 to 12 carbon atoms include: -CH2-, -CH2-CH2-, -CH(CH3)-, -CH2-CH2-CH2-, -CH2-CH(CH3)-, -CH(CH3)-CH2-, -C(CH3)2-, etc.

[0085] G 1 and G 2 The alkyl group can be chain-like or branched. The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 15, and even more preferably 1 to 10. Examples of alkyl groups include methyl, ethyl, isopropyl, butyl, isobutyl, hexyl, octyl, 2-ethylhexyl, etc.

[0086] From the viewpoint of improving the flowability of the mixture, the epoxy resin preferably contains at least one crystalline epoxy resin. Crystalline epoxy resins have a melting point and do not soften in the temperature range below the melting point, thus exhibiting excellent flowability.

[0087] Examples of crystalline epoxy resins include hydroquinone-type epoxy resins, bisphenol-type epoxy resins, thioether-type epoxy resins, biphenyl phenolic varnish-type epoxy resins, and biphenyl-type epoxy resins.

[0088] Commercially available crystalline epoxy resins include, for example, EPICLON 860, EPICLON 1050, EPICLON 1055, EPICLON 2050, EPICLON 3050, EPICLON 4050, EPICLON 7050, EPICLON HM-091, EPICLON HM-101, EPICLON N-730A, EPICLON N-740, EPICLON N-770, EPICLON N-775, EPICLON N-865, EPICLON HP-4032D, EPICLON HP-7200L, EPICLON HP-7200, EPICLON HP-7200H, EPICLON HP-7200HHH, EPICLON HP-7200HHH, EPICLON HP-4700, and EPICLON... HP-4710, EPICLON HP-4770, EPICLON HP-5000, EPICLON HP-6000 and N500P-2 (these are trade names manufactured by DIC Corporation), NC-3000, NC-3000-L, NC-3000-H, NC-3100, CER-3000-L, NC-2000-L, XD-1000, NC-7000-L, NC-7300-L, EPPN-501H, EPPN-501HY, EPPN-50 2H, EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, BREN-10S (the above are trade names manufactured by Nippon Kayaku Co., Ltd.), YX-4000, YX-4000H, YL4121H, YX-8800 (the above are trade names manufactured by Mitsubishi Chemical Co., Ltd.), etc.

[0089] In this embodiment, the epoxy resin (A) preferably includes an epoxy resin that is solid at room temperature (25°C).

[0090] The content of epoxy resin that is solid at room temperature (25°C) is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 95% by mass or more, relative to the total amount of epoxy resin. By satisfying the above-mentioned configuration with epoxy resin (A), adhesion during storage of the mixture can be suppressed.

[0091] The content of epoxy resin (A) relative to the total mass of the bonded magnet mixture is preferably 0.3% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and even more preferably 0.8% by mass or more and 10% by mass or less. By satisfying the above range for the content of epoxy resin, both the magnetic properties and mechanical strength of the bonded magnet can be taken into account.

[0092] The epoxy resin content relative to the total volume of the bonded magnet mixture is preferably 0.5 vol% or more and 40 vol% or less, more preferably 0.8 vol% or more and 30 vol% or less, and even more preferably 1.0 vol% or more and 20 vol% or less. By satisfying the above-mentioned range for the epoxy resin content, both the magnetic properties and mechanical strength of the bonded magnet can be taken into account.

[0093] <Curing agent different from curing agents with imidazole structure (B)>

[0094] The mixture in the embodiment preferably contains a curing agent (B) that is different from the curing agent (D) having an imidazole structure.

[0095] Curing agents (B) that differ from curing agents with imidazole structures include, but are not limited to, aliphatic polyamines, polyaminoamides, polythiols, aromatic polyamines, acid anhydrides, phenolic resins, dicyandiamide (DICY), etc.

[0096] From the viewpoint of improving the heat resistance of bonded magnets, the curing agent (B) that is different from the curing agent with an imidazole structure is preferably an aromatic polyamine, an acid anhydride, a phenolic resin or dicyandiamide (DICY), with phenolic resin being more preferred.

[0097] Examples of aromatic polyamines include diaminodiphenylmethane, m-phenylenediamine, diaminodiphenyl sulfone, diethyltoluenediamine, trimethylenebis(4-aminobenzoate), and polytetramethylene oxide-di-p-aminobenzoate. Commercially available aromatic polyamines can be used, such as KAYAHARD AA (manufactured by Nippon Kayaku Co., Ltd.) and ETHACUR 100 (manufactured by Mitsui FineChemical Inc.).

[0098] Examples of acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0099] Examples of phenolic resins include aralkyl-type phenolic resins, dicyclopentadiene-type phenolic resins, salicylaldehyde-type phenolic resins, phenolic varnish-type phenolic resins, copolymers of benzaldehyde-type phenol and aralkyl-type phenol, p-xylene and / or m-xylene-modified phenolic resins, melamine-modified phenolic resins, terpene-modified phenolic resins, dicyclopentadiene-type naphthol resins, cyclopentadiene-modified phenolic resins, polycyclic aromatic ring-modified phenolic resins, biphenyl-type phenolic resins, and triphenylmethane-type phenolic resins. Phenolic resins can be copolymers composed of two or more of the above-mentioned types.

[0100] From the perspective of improving the heat resistance of bonded magnets, phenolic resin is preferably a phenolic varnish type phenolic resin.

[0101] Phenolic varnish-type phenolic resins include, for example, resins obtained by condensing or co-condensing phenols and / or naphthols with aldehydes under an acidic catalyst. Examples of phenols constituting phenolic varnish-type phenolic resins include phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. Examples of naphthols constituting phenolic varnish-type phenolic resins include α-naphthol, β-naphthol, and dihydroxynaphthol. Examples of aldehydes constituting phenolic varnish-type phenolic resins include formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0102] Curing agents (B) that differ from those with an imidazole structure can, for example, be compounds having two phenolic hydroxyl groups per molecule. Examples of compounds having two phenolic hydroxyl groups per molecule include: resorcinol, catechol, bisphenol A, bisphenol F, substituted or unsubstituted biphenols, etc.

[0103] One of the above-mentioned curing agents can be used alone, or two or more can be used in combination.

[0104] The ratio of the active groups (phenolic OH groups) in the curing agent that react with the epoxy groups in the epoxy resin to the epoxy groups in the epoxy resin is preferably 0.5 to 1.5 equivalents, more preferably 0.7 to 1.4 equivalents, and even more preferably 0.8 to 1.3 equivalents.

[0105] By ensuring that the ratio of active groups in the curing agent meets the above-mentioned range, the mechanical properties and heat resistance of the bonded magnet can be improved.

[0106] The curing agent (B), which is different from the curing agent with an imidazole structure in this embodiment, is preferably a curing agent that is solid at room temperature (25°C).

[0107] The content of the curing agent that is solid at room temperature (25°C) is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 95% by mass or more, relative to the total amount of the curing agent. By satisfying the above-described configuration of the curing agent, adhesion during storage of the mixture can be suppressed.

[0108] The content of the curing agent (B), which is different from the curing agent with an imidazole structure, is preferably 0.3% by mass or more and 20% by mass or less relative to the total mass of the bonded magnet mixture, more preferably 0.5% by mass or more and 15% by mass or less, and even more preferably 0.8% by mass or more and 10% by mass or less. By ensuring that the content of the curing agent (B), which is different from the curing agent with an imidazole structure, meets the above range, it is possible to balance the magnetic properties and mechanical strength of the bonded magnet.

[0109] The content of the curing agent (B), which is different from the curing agent with an imidazole structure, is preferably 0.5 vol% or more and 40 vol% or less relative to the total volume of the bonded magnet mixture, more preferably 0.8 vol% or more and 30 vol% or less, and even more preferably 1.0 vol% or more and 20 vol% or less. By ensuring that the content of the curing agent (B), which is different from the curing agent with an imidazole structure, meets the above range, both the magnetic properties and mechanical strength of the bonded magnet can be taken into account.

[0110] <Contains metal element particles (C)>

[0111] The mixture in this embodiment contains particles containing metallic elements.

[0112] Particles containing metallic elements may contain at least one element selected from the group consisting of elemental metals, alloys, and metal compounds. Alloys may contain at least one element selected from the group consisting of solid solutions, eutectics, and intermetallic compounds. Alloys may, for example, be stainless steel (Fe-Cr alloys, Fe-Ni-Cr alloys, etc.). Metal compounds may, for example, be oxides such as ferrites. Particles containing metallic elements may contain one or more metallic elements. The metallic elements contained in the particles may, for example, be base metals, noble metals, transition metals, or rare earth elements. The metallic element contained in the particles can be, for example, at least one selected from the group consisting of iron (Fe), 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), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). The particles may also contain elements other than metallic elements. For example, the particles may contain oxygen (O), beryllium (Be), phosphorus (P), boron (B), or silicon (Si).

[0113] Metal-containing particles can be used alone or in combination of two or more. When mixing two or more metal-containing particles, particles with different compositions, particle sizes (particle size distributions), shapes, specific surface areas, properties (isotropic or anisotropic), and surface treatments can be used together.

[0114] There are no limitations on the alloy composition containing metal element particles, as long as it does not reduce the curing properties of the resin composition.

[0115] Particles containing metallic elements are preferably magnetic particles.

[0116] Magnetic particles can be, for example, samarium-cobalt (Sm-Co) alloy particles (rare earth magnetic particles), neodymium-iron-boron (Nd-Fe-B) alloy particles (rare earth magnetic particles), samarium-iron-nitrogen (Sm-Fe-N) alloy particles (rare earth magnetic particles), iron-cobalt (Fe-Co) alloy particles, Al-Ni-Co alloy particles, ferrite system magnetic particles, etc.

[0117] The magnetic particles used in this embodiment are preferably rare earth magnetic particles.

[0118] In this embodiment, rare earth magnetic particles refer to magnetic particles containing rare earth elements.

[0119] Rare earth magnetic particles exhibit superior holding force and magnetic flux density compared to other magnetic particles, and can, for example, enhance the magnetic force of bonded magnets.

[0120] The shape of the magnetic particles is not particularly limited; they can be used individually or in combination, including spherical, flat, prismatic, and needle-shaped particles. The shape of the magnetic particles can be evaluated by measuring the roundness coefficient using image processing of microscopic observations. The roundness coefficient is defined by the following formula; the higher the value, the more rounded and spherical the particles are. From the viewpoint that magnetic particles are easy to rotate in magnetic field shaping and can improve orientation, it is preferable to include at least one type of magnetic particle with a roundness coefficient of 0.60 or higher.

[0121] Circularity coefficient = (4πS / L) 2 )

[0122] Where S is the two-dimensional projected area of ​​the particle, and L is the two-dimensional projected perimeter.

[0123] The particle size (particle size distribution) of magnetic particles can be used individually or in combination, with coarse magnetic particles (hereinafter referred to as "coarse particles") and fine magnetic particles (hereinafter referred to as "microparticles").

[0124] The average particle size (D50) of the coarse particles is preferably 30 μm or more and 300 μm or less, more preferably 40 μm or more and 250 μm or less. The coarse particles have high magnetic properties, thus the magnetic properties of the bonded magnet can be adjusted according to the amount of coarse particles added.

[0125] The average particle size (D50) of the microparticles is preferably 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less. Microparticles can increase the filling amount of magnetic particles and improve magnetic properties.

[0126] The average particle size and particle size distribution of the magnetic particles were determined using a laser diffraction particle size distribution measuring device (HELOS manufactured by Japan Laser Corp.).

[0127] The specific surface area of ​​the magnetic particles is preferably 0.005 m². 2 / g or more and 5.0m 2 / g or less, more preferably 0.01m 2 / g or more and 1.5m 2 / g or less, more preferably 0.03m 2 / g or more and 1.3m 2 / g or less, particularly preferably 0.05m 2 / g or more and 1.0m 2 / g or less.

[0128] By using magnetic particles to achieve the above-mentioned structure, in addition to taking into account the magnetic properties and mechanical strength of the bonded magnet, the fluidity of the mixture can also be improved.

[0129] As a method for controlling the specific surface area of ​​magnetic particles, one approach is to adjust it by changing the shape and average particle size of the magnetic particles. When using a combination of multiple magnetic particles, the specific surface area of ​​the mixed magnetic particles can be adjusted to the range described above.

[0130] The specific surface area was measured using a BET specific surface area measuring device, with a N2 / He mixture of 30 / 70 (volume ratio) as the adsorbed gas.

[0131] It should be noted that when there are two or more types of magnetic particles, the specific surface area is calculated based on the specific surface area and content ratio of each magnetic particle, using the average value of the entire magnetic particle.

[0132] There are no particular limitations on the properties of magnetic particles; anisotropic and isotropic magnetic particles can be used individually or in combination. By using anisotropic magnetic particles to create mixtures and then shaping them using a magnetic field to orient the magnetic particles within the bonded magnet, the magnetic properties can be improved.

[0133] The magnetic particles are preferably treated with rust prevention. Rust prevention treatments include, for example, phosphoric acid treatment to form a phosphate compound layer, metal alkoxy oligomer treatment to form an organometallic compound layer, coupling treatment to form a coupling agent layer, and slow oxidation treatment to form an oxide coating. It should be noted that rust prevention treatments can be performed using a single type or in combination.

[0134] The content of magnetic particles relative to the total mass of the bonded magnet mixture is preferably 70% by mass or more and 99.5% by mass or less, more preferably 80% by mass or more and 99.0% by mass or less, and even more preferably 90% by mass or more and 98.5% by mass or less. By satisfying the above range for the content of magnetic particles, both the magnetic properties and mechanical strength of the bonded magnet can be taken into account.

[0135] <Curing agent with imidazole structure (D)>

[0136] The mixture of this embodiment contains the compound represented by formula (1) and / or the compound represented by formula (2) as a curing agent (D) having an imidazole structure.

[0137] Surprisingly, by satisfying the above-described configuration in the mixture of this embodiment, it is possible to achieve a long service life during the manufacturing process, minimal changes in properties caused by heating during the molding of bonded magnets, and high mechanical strength even when the thermosetting resin is cured at low temperatures. Such effects cannot be easily inferred from the structure of the curing agent (D) having an imidazole structure.

[0138] Furthermore, during the formation of the mixture of this embodiment, the inventors verified the effects of imidazole compounds having various structures and found that the curing agent (D) having an imidazole structure in this embodiment is the most suitable compound for imparting the above-mentioned effects. The mechanism of the above-mentioned effects is believed to be as follows.

[0139] In this embodiment, the curing agent (D) with an imidazole structure is a compound with an imidazole structure. Generally, it is known that the nitrogen atom on an imidazole compound has the ability to coordinate with metals, and it is assumed that when an imidazole compound coexists with metal-containing particles (magnetic particles), the nitrogen atom of the imidazole compound adsorbs onto the metal-containing particles (magnetic particles). Therefore, when using imidazole compounds with various structures to prepare mixtures, it is possible that the imidazole compound in the mixture will be concentrated near the surface of the metal-containing particles (magnetic particles), resulting in reduced dispersibility of the imidazole compound.

[0140] On the other hand, the compounds represented by formulas (1) and (2) have a structure in which a hydroxyphenyl group is substituted at the 2-position of the imidazole relative to the imidazole structure. It is believed that the nitrogen atom, which is the active site of the imidazole, forms an intramolecular hydrogen bond with the adjacent hydroxyphenyl group. At low temperatures (e.g., below 120°C), the nucleophilicity of the nitrogen atom on the imidazole is suppressed, resulting in uniform dispersion in the mixture. Furthermore, since the nucleophilicity of the epoxy group is also suppressed, the usable time during the manufacturing process is excellent, and the property changes during the molding of bonded magnets can also be suppressed.

[0141] Furthermore, it is speculated that during the curing of the bonded magnet (e.g., above 120°C), as the temperature of the mixture increases, the intramolecular hydrogen bonds gradually separate, and a portion of the compounds represented by formulas (1) and (2) adsorbs onto the metal-containing particles (magnetic particles). As a result, when using the compounds represented by formulas (1) and (2) to prepare the cured bonded magnet, the compounds represented by formulas (1) and (2) are dispersed throughout the mixture system, and the concentration near the surface of the metal-containing particles (magnetic particles) can be selectively increased. Therefore, while maintaining the overall curing strength of the bonded magnet, the crosslinking density near the surface of the metal-containing particles (magnetic particles) can be particularly increased.

[0142] Typically, the mechanical strength of composite materials (resin components, magnetic particles, etc.) tends to be weakest at the interface between the materials. However, it is speculated that by using the compounds represented by formulas (1) and (2), the crosslinking density at the interface increases, and high mechanical strength can be imparted when thermosetting resins are cured at low temperatures.

[0143]

[0144] In formulas (1) and (2), R1 and R2 are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, halogen atom, alkyl group with 1 to 20 carbon atoms that may have substituents, and cycloalkyl group with 6 to 20 carbon atoms that may have substituents. R1 and R2 may be the same or different, and R1 and R2 may be bonded together to form a fused ring that is not aromatic.

[0145] X is any one of the following groups: hydrogen atom, alkyl group with 1 to 20 carbon atoms that have substituted groups, alkenyl group with 2 to 20 carbon atoms that have substituted groups, aralkyl group with 7 to 20 carbon atoms that have substituted groups, and heteroarylalkyl group with 4 to 20 carbon atoms that have substituted groups.

[0146] Y and Z are each independently selected from the group consisting of hydrogen atom, halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group with 1 to 20 carbon atoms optionally having a substituent, alkoxy group with 1 to 20 carbon atoms optionally having a substituent, alkenyl group with 2 to 20 carbon atoms optionally having a substituent, aryl group with 6 to 20 carbon atoms optionally having a substituent, aryloxy group with 6 to 20 carbon atoms optionally having a substituent, and acyl group with 1 to 20 carbon atoms optionally having a substituent. Y and Z are each optionally the same or different, and two or more Y groups or two or more Z groups are optionally bonded to form a monocyclic or fused ring. m and n are each independently an integer from 1 to 4.

[0147] As described above, R1 and R2 in formula (1) are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, halogen atom, alkyl group with 1 to 20 carbon atoms with optional substituents, and cycloalkyl group with 6 to 20 carbon atoms with optional substituents. R1 and R2 are optionally bonded to form a fused ring that is not aromatic. R1 and R2 are each optionally the same or different.

[0148] The alkyl group having 1 to 20 carbon atoms can be chain-like or branched. The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 15, and even more preferably 1 to 10. Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, isopropyl, butyl, isobutyl, hexyl, octyl, 2-ethylhexyl, etc.

[0149] The number of carbon atoms in a cycloalkyl group having 6 to 20 carbon atoms is preferably 6 to 18, more preferably 6 to 15. Examples of cycloalkyl groups having 6 to 20 carbon atoms include cyclohexyl, cycloheptyl, and cyclooctyl.

[0150] Examples of non-aromatic fused rings formed by the bonding of R1 and R2 include cyclopentane, cyclohexane, and dicyclopentadiene.

[0151] In addition, the alkyl, cycloalkyl, and non-aromatic fused rings formed by the bonding of R1 and R2 may also have substituents, such as halogen atoms, hydroxyl groups, alkoxy groups, nitro groups, etc., preferably hydroxyl and alkoxy groups.

[0152] In the aforementioned formulas (1) and (2), X is any one of the following groups: hydrogen atom, alkyl group with 1 to 20 carbon atoms having a substituent, alkenyl group with 2 to 20 carbon atoms having a substituent, aralkyl group with 7 to 20 carbon atoms having a substituent, and heteroarylalkyl group with 4 to 20 carbon atoms having a substituent.

[0153] The alkyl group having 1 to 20 carbon atoms in X can be either chain-like or branched. The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 15. Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, isopropyl, butyl, isobutyl, hexyl, octyl, etc.

[0154] The alkenyl group with 2 to 20 carbon atoms in X can be chain-like or branched. The number of carbon atoms in the alkenyl group is preferably 2 to 18, more preferably 2 to 15. Examples of alkenyl groups with 2 to 20 carbon atoms include vinyl, aryl, 1-propenyl, isopropenyl, 2-butenyl, 3-butenyl, 2-pentenyl, and 2-hexenyl.

[0155] The aralkyl group with 7 to 20 carbon atoms in X can be either chain-like or branched. The number of carbon atoms in the aralkyl group is preferably 7 to 18, more preferably 7 to 15. Examples of aralkyl groups with 7 to 20 carbon atoms include benzyl, phenethyl, and naphthylmethyl.

[0156] The heteroaryl alkyl group having 4 to 20 carbon atoms as X can be either chain-like or branched, and the heteroaryl alkyl group preferably has 4 to 18 carbon atoms, more preferably 4 to 15 carbon atoms. Examples of heteroaryl alkyl groups having 4 to 20 carbon atoms include triazinemethyl, triazineethyl, 2-pyridylmethyl, 2-pyridylethyl, 3-pyridylmethyl, 3-pyridylethyl, 4-pyridylmethyl, and 4-pyridylethyl.

[0157] In addition, the aforementioned alkyl, alkenyl, aralkyl, and heteroarylalkyl groups may optionally have substituents. Examples of substituents include halogen atoms, cyano, nitro, hydroxyl, alkoxy, amino, ester, arylsulfonyl, alkylsulfonyl, and phenyl groups, with cyano, alkoxy, amino, ester, and phenyl groups being preferred.

[0158] In formulas (1) and (2) above, Y and Z are each independently selected from the group consisting of hydrogen atom, halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group with 1 to 20 carbon atoms that have substituted groups, alkoxy group with 1 to 20 carbon atoms that have substituted groups, alkenyl group with 2 to 20 carbon atoms that have substituted groups, aryl group with 6 to 20 carbon atoms that have substituted groups, aryloxy group with 6 to 20 carbon atoms that have substituted groups, and acyl group with 1 to 20 carbon atoms that have substituted groups. Two or more Y groups or two or more Z groups are each optionally bonded to form a monocyclic or fused ring. m and n are each independently integers from 1 to 4.

[0159] The alkyl groups with 1 to 20 carbon atoms in Y and Z can be either chain-like or branched. The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 15. Examples of alkyl groups with 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, octyl, 2-ethylhexyl, decyl, undecyl, etc.

[0160] The alkoxy groups with 1 to 20 carbon atoms in Y and Z can be either chain-like or branched. The carbon number is preferably 1 to 18, more preferably 1 to 15. Examples of alkoxy groups with 1 to 20 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, butoxy, hexoxy, and 2-ethylhexoxy.

[0161] The alkenyl groups with 2 to 20 carbon atoms in Y and Z can be either chain-like or branched. The number of carbon atoms in the alkenyl group is preferably 2 to 18, more preferably 2 to 15. Examples of alkenyl groups with 2 to 20 carbon atoms include vinyl, aryl, 1-propenyl, isopropenyl, 2-butenyl, 3-butenyl, 2-pentenyl, and 2-hexenyl.

[0162] The aryl group having 6 to 20 carbon atoms in Y and Z is preferably 6 to 18, more preferably 6 to 15. Examples of aryl groups having 6 to 20 carbon atoms include phenyl, naphthyl, anthraceneyl, and biphenyl.

[0163] In addition, structures that form monocyclic or fused rings by bonding two or more Y or two or more Z bonds include, for example, naphthyl and anthraceneyl.

[0164] The number of carbons in the acyl groups of Y and Z with 1 to 20 carbons is preferably 1 to 18, more preferably 1 to 15. Examples of acyl groups with 1 to 20 carbons include acetyl, benzoyl, and neopentyl.

[0165] In addition, the alkyl, alkoxy, alkenyl, aryl, aryloxy, and acyl groups mentioned above may optionally have substituents. Examples of substituents include alkyl, halogen atoms, hydroxyl, carboxyl, alkoxy, nitro, ester, and phenyl groups, with alkyl, hydroxyl, carboxyl, and alkoxy groups being preferred.

[0166] Y can be any of the ortho, meta, or para positions of the phenyl group that replaces the 2-position substituent of the imidazole. In the case of a substituent, it is preferred that the position other than the ortho position is substituted, more preferably that the position at least the meta position is substituted, and even more preferably that the meta position is substituted by a hydroxyl group or optionally by an alkoxy group having 1 to 20 carbon atoms.

[0167] In the above, Y and Z in formulas (1) and (2) are more preferably each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, alkoxy group with 1 to 20 carbon atoms without substituents, alkyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, alkoxy group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, aryl group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, aryloxy group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, and acyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents.

[0168] Furthermore, when Y and Z are independently hydroxyl, carboxyl, alkoxy group with 1 to 20 carbon atoms without substituents, alkyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl as substituents, alkoxy group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl as substituents, aryl group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl as substituents, aryloxy group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl as substituents, or acyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl as substituents, the coordination of the metal-containing particles increases, thus tending to improve the mechanical strength of the bonded magnet.

[0169] As the compound represented by the above formula (1), although not limited to the following, the following imidazole compounds can be listed.

[0170] Examples include 2-(2-hydroxyphenyl)imidazole, 2-(2-hydroxyphenyl)-4-methylimidazole, 2-(2-hydroxyphenyl)-5-methylimidazole, 4-ethyl-2-(2-hydroxyphenyl)imidazole, 5-ethyl-2-(2-hydroxyphenyl)imidazole, 4,5-dimethyl-2-(2-hydroxyphenyl)imidazole, 4-ethyl-(2-hydroxyphenyl)-5-methylimidazole, (2-hydroxyphenyl)-4-isopropyl-5-methylimidazole, 4-butyl-(2-hydroxyphenyl)-5-methylimidazole, 2-(2-hydroxy-3-methylphenyl)imidazole, 2-(2-hydroxy-3-methylphenyl)-4-methylimidazole, 2-(2-hydroxy-3-methylphenyl)-5-methylimidazole, 4-ethyl-2-(2-hydroxyphenyl)-5-methylimidazole, and 4-ethyl-2-(2-hydroxyphenyl)-5-methylimidazole. (2-hydroxy-3-methylphenyl)imidazolium, 5-ethyl-2-(2-hydroxy-3-methylphenyl)imidazolium, 4,5-dimethyl-2-(2-hydroxy-3-methylphenyl)imidazolium, 4-ethyl-(2-hydroxy-3-methylphenyl)-5-methylimidazolium, (2-hydroxy-3-methylphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxy-3-methylphenyl)-5-methylimidazolium, 2-(2-hydroxy-4-methylphenyl)imidazolium, 2-(2-hydroxy-4-methylphenyl)-4-methylimidazolium, 2-(2-hydroxy-4-methylphenyl)-5-methylimidazolium, 4-ethyl-2-(2-hydroxy-4-methylphenyl)imidazolium, 5-ethyl-2-(2-hydroxy-4-methylphenyl)imidazolium, etc.

[0171] Additionally, examples include 4,5-dimethyl-2-(2-hydroxy-4-methylphenyl)imidazolium, 4-ethyl-(2-hydroxy-4-methylphenyl)-5-methylimidazolium, (2-hydroxy-4-methylphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxy-4-methylphenyl)-5-methylimidazolium, 2-(2-hydroxy-5-methylphenyl)imidazolium, 2-(2-hydroxy-5-methylphenyl)-4-methylimidazolium, 2-(2-hydroxy-5-methylphenyl)-5-methylimidazolium, 4-ethyl-2-(2-hydroxy-5-methylphenyl)imidazolium, and 5-ethyl-2-(2-hydroxy-5-methylphenyl)imidazolium. 4,5-Dimethyl-2-(2-hydroxy-5-methylphenyl)imidazolium, 4-ethyl-(2-hydroxy-5-methylphenyl)-5-methylimidazolium, (2-hydroxy-5-methylphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxy-5-methylphenyl)-5-methylimidazolium, 2-(3-tert-butyl-2-hydroxyphenyl)imidazolium, 2-(3-tert-butyl-2-hydroxyphenyl)-4-methylimidazolium, 2-(3-tert-butyl-2-hydroxyphenyl)-5-methylimidazolium, 2-(3-tert-butyl-2-hydroxyphenyl)-4-ethylimidazolium, 2-(3-tert-butyl-2-hydroxyphenyl)-5-ethylimidazolium, etc.

[0172] Furthermore, examples include 2-(3-tert-butyl-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(3-tert-butyl-2-hydroxyphenyl)-4-ethyl-5-methylimidazole, 2-(3-tert-butyl-2-hydroxyphenyl)-4-isopropyl-5-methylimidazole, 4-butyl-2-(3-tert-butyl-2-hydroxyphenyl)-5-methylimidazole, 2-(4-fluoro-2-hydroxyphenyl)imidazole, 2-(4-fluoro-2-hydroxyphenyl)-4-methylimidazole, 2-(4-fluoro-2-hydroxyphenyl)-5-methylimidazole, 2-(4-fluoro-2-hydroxyphenyl)-4-ethylimidazole, and 2-(4-fluoro-2-hydroxyphenyl)- 5-Ethylimidazole, 2-(4-fluoro-2-hydroxyphenyl)-4,5-dimethylimidazole, 4-ethyl-2-(4-fluoro-2-hydroxyphenyl)-5-methylimidazole, 2-(4-fluoro-2-hydroxyphenyl)-4-isopropyl-5-methylimidazole, 4-butyl-2-(4-fluoro-2-hydroxyphenyl)-5-methylimidazole, 2-(4-chloro-2-hydroxyphenyl)imidazole, 2-(4-chloro-2-hydroxyphenyl)-4-methylimidazole, 2-(4-chloro-2-hydroxyphenyl)-5-methylimidazole, 2-(4-chloro-2-hydroxyphenyl)-4-ethylimidazole, 2-(4-chloro-2-hydroxyphenyl)-5-ethylimidazole, etc.

[0173] Furthermore, examples include 2-(4-chloro-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(4-chloro-2-hydroxyphenyl)-4-ethyl-5-methylimidazole, 2-(4-chloro-2-hydroxyphenyl)-4-isopropyl-5-methylimidazole, 4-butyl-2-(4-chloro-2-hydroxyphenyl)-5-methylimidazole, 2-(4-bromo-2-hydroxyphenyl)imidazole, 2-(4-bromo-2-hydroxyphenyl)-4-methylimidazole, and 2-(4-bromo-2-hydroxyphenyl)-5-methylimidazole. Imidazole, 2-(4-bromo-2-hydroxyphenyl)-4-ethylimidazole, 2-(4-bromo-2-hydroxyphenyl)-5-ethylimidazole, 2-(4-bromo-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(4-bromo-2-hydroxyphenyl)-4-ethyl-5-methylimidazole, 2-(4-bromo-2-hydroxyphenyl)-4-isopropyl-5-methylimidazole, 2-(4-bromo-2-hydroxyphenyl)-4-butyl-5-methylimidazole, 2-(2,3-dihydroxyphenyl)imidazole, etc.

[0174] Furthermore, examples include 2-(2,3-dihydroxyphenyl)-4-methylimidazole, 2-(2,3-dihydroxyphenyl)-5-methylimidazole, 2-(2,3-dihydroxyphenyl)-4-ethylimidazole, 2-(2,3-dihydroxyphenyl)-5-ethylimidazole, 2-(2,3-dihydroxyphenyl)-4,5-dimethylimidazole, 2-(2,3-dihydroxyphenyl)-4-phenylimidazole, 2-(2,3-dihydroxyphenyl)-5-phenylimidazole, and 2-(2,3-dihydroxyphenyl)-4,5- Diphenylimidazole, 2-(2,5-dihydroxyphenyl)imidazole, 2-(2,5-dihydroxyphenyl)-4-methylimidazole, 2-(2,5-dihydroxyphenyl)-5-methylimidazole, 2-(2,5-dihydroxyphenyl)-4-ethylimidazole, 2-(2,5-dihydroxyphenyl)-5-ethylimidazole, 2-(2,5-dihydroxyphenyl)-4,5-dimethylimidazole, 2-(2,5-dihydroxyphenyl)-4-phenylimidazole, 2-(2,5-dihydroxyphenyl)-5-phenylimidazole, 2-(2 5-Dihydroxyphenyl)-4,5-diphenylimidazole, 2-(2-hydroxy-4-methoxyphenyl)imidazole, 2-(2-hydroxy-4-methoxyphenyl)-4-methylimidazole, 2-(2-hydroxy-4-methoxyphenyl)-5-methylimidazole, 4-ethyl-2-(2-hydroxy-4-methoxyphenyl)imidazole, 5-ethyl-2-(2-hydroxy-4-methoxyphenyl)imidazole, 4,5-dimethyl-2-(2-hydroxy-4-methoxyphenyl)imidazole, 2-(2-hydroxy-4-methoxyphenyl)imidazole 4-(2-hydroxy-4-methoxyphenyl)-5-phenylimidazole, 4,5-diphenyl-2-(2-hydroxy-4-methoxyphenyl)imidazole, 2-(2-hydroxy-3-methoxyphenyl)imidazole, 2-(2-hydroxy-3-methoxyphenyl)-4-methylimidazole, 2-(2-hydroxy-3-methoxyphenyl)-5-methylimidazole, 4-ethyl-2-(2-hydroxy-3-methoxyphenyl)imidazole, 5-ethyl-2-(2-hydroxy-3-methoxyphenyl)imidazole, etc.

[0175] Additionally, examples include 4,5-dimethyl-2-(2-hydroxy-3-methoxyphenyl)imidazolium, 2-(2-hydroxy-3-methoxyphenyl)-4-phenylimidazolium, 2-(2-hydroxy-3-methoxyphenyl)-5-phenylimidazolium, 4,5-diphenyl-2-(2-hydroxy-3-methoxyphenyl)imidazolium, 2-(2-hydroxy-5-methoxyphenyl)imidazolium, 2-(2-hydroxy-5-methoxyphenyl)-4-methylimidazolium, 2-(2-hydroxy-5-methoxyphenyl)-5-methylimidazolium, and 4-ethyl-2-( 2-Hydroxy-5-methoxyphenyl)imidazolium, 5-ethyl-2-(2-hydroxy-5-methoxyphenyl)imidazolium, 4,5-dimethyl-2-(2-hydroxy-5-methoxyphenyl)imidazolium, 2-(2-hydroxy-5-methoxyphenyl)-4-phenylimidazolium, 2-(2-hydroxy-5-methoxyphenyl)-5-phenylimidazolium, 4,5-diphenyl-2-(2-hydroxy-5-methoxyphenyl)imidazolium, 2-(2-hydroxy-6-methoxyphenyl)imidazolium, 2-(2-hydroxy-6-methoxyphenyl)-4-methylimidazolium 2-(2-hydroxy-6-methoxyphenyl)-5-methylimidazole, 4-ethyl-2-(2-hydroxy-6-methoxyphenyl)imidazole, 5-ethyl-2-(2-hydroxy-6-methoxyphenyl)imidazole, 4,5-dimethyl-2-(2-hydroxy-6-methoxyphenyl)imidazole, 2-(2-hydroxy-6-methoxyphenyl)-4-phenylimidazole, 2-(2-hydroxy-6-methoxyphenyl)-5-phenylimidazole, 4,5-diphenyl-2-(2-hydroxy-6-methoxyphenyl)imidazole, 2-(3-ethoxy) 2-(3-ethoxy-2-hydroxyphenyl)imidazolium, 2-(3-ethoxy-2-hydroxyphenyl)-4-methylimidazolium, 2-(3-ethoxy-2-hydroxyphenyl)-5-methylimidazolium, 2-(3-ethoxy-2-hydroxyphenyl)-4-ethylimidazolium, 2-(3-ethoxy-2-hydroxyphenyl)-5-ethylimidazolium, 4,5-dimethyl-2-(3-ethoxy-2-hydroxyphenyl)imidazolium, 2-(3-ethoxy-2-hydroxyphenyl)-4-phenylimidazolium, 2-(3-ethoxy-2-hydroxyphenyl)-5-phenylimidazolium, etc.

[0176] Furthermore, examples include 4,5-diphenyl-2-(3-ethoxy-2-hydroxyphenyl)imidazolium, 2-(5-ethoxy-2-hydroxyphenyl)imidazolium, 2-(5-ethoxy-2-hydroxyphenyl)-4-methylimidazolium, 2-(5-ethoxy-2-hydroxyphenyl)-5-methylimidazolium, 2-(5-ethoxy-2-hydroxyphenyl)-4-ethylimidazolium, 2-(5-ethoxy-2-hydroxyphenyl)-5-ethylimidazolium, 4,5-dimethyl-2-(5-ethoxy-2-hydroxyphenyl)imidazolium, 2-(5-ethoxy-2-hydroxyphenyl)-4-phenylimidazolium, 2-(5-ethoxy-2-hydroxyphenyl)-5-phenylimidazolium, 4,5-diphenyl-2-(5-ethoxy-2-hydroxyphenyl)imidazolium, and 2-(4-allyl-2-hydroxy-3-methoxyphenyl) Imidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-4-methylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-5-methylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-4-ethylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-5-ethylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-4,5-dimethylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-4-phenylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-5-phenylimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)-4,5-diphenylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)imidazole, etc.

[0177] Furthermore, examples include 2-(4,6-dimethoxy-2-hydroxyphenyl)-4-methylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-5-methylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-4-ethylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-5-ethylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-4-phenylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-5-phenylimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)-4,5-diphenylimidazole, 2-(2-fluoro-5-hydroxyphenyl)imidazole, and 2-(2-fluoro-5-hydroxyphenyl)-4-methylimidazole. 2-(2-fluoro-5-hydroxyphenyl)-5-methylimidazole, 2-(2-fluoro-5-hydroxyphenyl)-4-ethylimidazole, 2-(2-fluoro-5-hydroxyphenyl)-5-ethylimidazole, 2-(2-fluoro-5-hydroxyphenyl)-4,5-dimethylimidazole, 2-(2-fluoro-5-hydroxyphenyl)-4-phenylimidazole, 2-(2-fluoro-5-hydroxyphenyl)-5-phenylimidazole, 2-(2-fluoro-5-hydroxyphenyl)-4,5-diphenylimidazole, 2-(5-fluoro-2-hydroxyphenyl)imidazole, 2-(5-fluoro-2-hydroxyphenyl)-4-methylimidazole, 2-(5-fluoro-2-hydroxyphenyl)-5-methylimidazole, 2-(5-fluoro-2-hydroxyphenyl)-4-ethylimidazole, 2-(5-fluoro-2-hydroxyphenyl)-5-ethylimidazole, etc.

[0178] Furthermore, examples include 2-(5-fluoro-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(5-fluoro-2-hydroxyphenyl)-4-phenylimidazole, 2-(5-fluoro-2-hydroxyphenyl)-5-phenylimidazole, 2-(5-fluoro-2-hydroxyphenyl)-4,5-diphenylimidazole, 2-(5-chloro-2-hydroxyphenyl)imidazole, 2-(5-chloro-2-hydroxyphenyl)-4-methylimidazole, 2-(5-chloro-2-hydroxyphenyl)-5-methylimidazole, 2-(5-chloro-2-hydroxyphenyl)-4-ethylimidazole, 2-(5-chloro-2-hydroxyphenyl)-5-ethylimidazole, 2-(5-chloro-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(5-chloro-2-hydroxyphenyl)-4-phenyl ... 2-(5-chloro-2-hydroxyphenyl)-5-phenylimidazole, 2-(5-bromo-2-hydroxyphenyl)-4,5-diphenylimidazole, 2-(5-bromo-2-hydroxyphenyl)imidazole, 2-(5-bromo-2-hydroxyphenyl)-4-methylimidazole, 2-(5-bromo-2-hydroxyphenyl)-5-methylimidazole, 2-(5-bromo-2-hydroxyphenyl)-4-ethylimidazole, 2-(5-bromo-2-hydroxyphenyl)-5-ethylimidazole, 2-(5-bromo-2-hydroxyphenyl)-4,5-dimethylimidazole, 2-(5-bromo-2-hydroxyphenyl)-4-phenylimidazole, 2-(5-bromo-2-hydroxyphenyl)-5-phenylimidazole, 2-(5-bromo-2-hydroxyphenyl)-4,5-diphenylimidazole, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)imidazole, etc.

[0179] Additionally, examples include 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-4-methylimidazole, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-5-methylimidazole, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-4-ethylimidazole, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-5-ethylimidazole, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-4,5-dimethylimidazole, and 2-(6- Fluoro-2-hydroxy-3-methoxyphenyl)-4-phenylimidazolium, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-5-phenylimidazolium, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)-4,5-diphenylimidazolium, 2-(1-hydroxynaphthyl-2-yl)imidazolium, 2-(1-hydroxynaphthyl-2-yl)-4-methylimidazolium, 2-(1-hydroxynaphthyl-2-yl)-5-methylimidazolium, 2-(1-hydroxynaphthyl-2-yl)- 4-Ethylimidazole, 2-(1-hydroxynaphth-2-yl)-5-ethylimidazole, 4,5-dimethyl-2-(1-hydroxynaphth-2-yl)imidazole, 2-(1-hydroxynaphth-2-yl)-4-phenylimidazole, 2-(1-hydroxynaphth-2-yl)-5-phenylimidazole, 4,5-diphenyl-2-(1-hydroxynaphth-2-yl)imidazole, 2-(2-hydroxynaphth-1-yl)imidazole, 2-(2-hydroxynaphth-1-yl)-4-methylimidazole 2-(2-hydroxynaphthyl-1-yl)-5-methylimidazolium, 2-(2-hydroxynaphthyl-1-yl)-4-ethylimidazolium, 2-(2-hydroxynaphthyl-1-yl)-5-ethylimidazolium, 4,5-dimethyl-2-(2-hydroxynaphthyl-1-yl)imidazolium, 2-(2-hydroxynaphthyl-1-yl)-4-phenylimidazolium, 2-(2-hydroxynaphthyl-1-yl)-5-phenylimidazolium, 4,5-diphenyl-2-(2-hydroxynaphthyl-1-yl)imidazolium, etc.

[0180] As the compound represented by formula (1), 2-(2-hydroxyphenyl)imidazolium, 2-(2-hydroxyphenyl)-4-methylimidazolium, 2-(2-hydroxyphenyl)-5-methylimidazolium, 4-ethyl-(2-hydroxyphenyl)-5-methylimidazolium, (2-hydroxyphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxyphenyl)-5-methylimidazolium, 2-(2-hydroxy-3-methoxyphenyl)imidazolium and 2-(2-hydroxy-5-methoxyphenyl)imidazolium are preferred.

[0181] As the compound represented by the above formula (2), although not limited to the following, the following imidazole compounds can be listed.

[0182] Examples include 2-(2-hydroxyphenyl)benzimidazole, 2-(2-hydroxy-3-methylphenyl)benzimidazole, 2-(2-hydroxy-4-methylphenyl)benzimidazole, 2-(2-hydroxy-5-methylphenyl)benzimidazole, 2-(3-tert-butyl-2-hydroxyphenyl)benzimidazole, 2-(4-fluoro-2-hydroxyphenyl)benzimidazole, 2-(4-chloro-2-hydroxyphenyl)benzimidazole, 2-(4-bromo-2-hydroxyphenyl)benzimidazole, 2-(2,3-dihydroxyphenyl)benzimidazole, 2-(2,5-dihydroxyphenyl)benzimidazole, 2-(2-hydroxy-4-methoxyphenyl)benzimidazole, 2-(2-hydroxy-3-methoxyphenyl)benzimidazole, and 2-(2-hydroxy-5-methoxyphenyl)benzimidazole. Zyrazoles, 2-(2-hydroxy-6-methoxyphenyl)benzimidazole, 2-(3-ethoxy-2-hydroxyphenyl)benzimidazole, 2-(5-ethoxy-2-hydroxyphenyl)benzimidazole, 2-(4-allyl-2-hydroxy-3-methoxyphenyl)benzimidazole, 2-(4,6-dimethoxy-2-hydroxyphenyl)benzimidazole, 2-(5-fluoro-2-hydroxyphenyl)benzimidazole, 2-(5-chloro-2-hydroxyphenyl)benzimidazole, 2-(5-bromo-2-hydroxyphenyl)benzimidazole, 2-(6-fluoro-2-hydroxy-3-methoxyphenyl)benzimidazole, 2-(1-hydroxynaphth-2-yl)benzimidazole, 2-(2-hydroxynaphth-1-yl)benzimidazole, 2-(2-hydroxyphenyl)benzimidazole-6-carboxylic acid, etc.

[0183] Among these, from the viewpoint that excellent solubility in epoxy resin (A) or solvent can yield a homogeneous mixture, and also has high heat resistance, as the compound represented by formula (1), it is preferable that R1 and R2 are both hydrogen atoms or have different substituents, for example more preferably 2-(2-hydroxyphenyl)imidazolium, 2-(2-hydroxyphenyl)-4-methylimidazolium, 2-(2-hydroxyphenyl)-5-methylimidazolium, 4-ethyl-(2-hydroxyphenyl)-5-methylimidazolium, (2-hydroxyphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxyphenyl)-5-methylimidazolium, 2-(2-hydroxy-3-methoxyphenyl)imidazolium and 2-(2-hydroxy-5-methoxyphenyl)imidazolium, and even more preferably 2-(2-hydroxyphenyl)imidazolium.

[0184] Furthermore, from the viewpoint of obtaining the same effect, the compounds represented by formula (2) are preferably 2-(2-hydroxyphenyl)benzimidazole, 2-(2-hydroxy-3-methoxyphenyl)benzimidazole, 2-(2-hydroxy-5-methoxyphenyl)benzimidazole, 2-(1-hydroxynaphthyl-2-yl)benzimidazole, 2-(2-hydroxynaphthyl-1-yl)benzimidazole and 2-(2-hydroxyphenyl)benzimidazole-6-carboxylic acid, and more preferably 2-(2-hydroxyphenyl)benzimidazole, 2-(2-hydroxy-3-methoxyphenyl)benzimidazole and 2-(2-hydroxy-5-methoxyphenyl)benzimidazole.

[0185] In the mixture of this embodiment, the content of the curing agent (D) having an imidazole structure is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of epoxy resin (A). By ensuring that the content of the curing agent meets the above range, the mechanical strength during low-temperature curing can be easily controlled.

[0186] Furthermore, the content of the curing agent (D) having an imidazole structure is preferably 15.0 parts by weight or less, more preferably 12.0 parts by weight or less, and even more preferably 10.0 parts by weight or less, relative to 100 parts by weight of epoxy resin (A). By ensuring that the content of the curing agent meets the above range, the storage stability of the mixture can be easily controlled.

[0187] From the viewpoint of mechanical strength, the content of the curing agent (D) having an imidazole structure (the content of the curing agent (Z) described below) is preferably less than 5.0% by mass, more preferably less than 3.0% by mass, and even more preferably less than 1.0% by mass, relative to the total mass of the mixture of this embodiment. Furthermore, from the viewpoint of the heat resistance of the bonded magnet, it is preferably more than 0.01% by mass, more preferably more than 0.03% by mass, and even more preferably more than 0.05% by mass, relative to the total mass of the mixture of this embodiment.

[0188] <Ratio of the specific surface area of ​​magnetic particles to the content of curing agent (D) with an imidazole structure>

[0189] In the bonded magnet mixture of this embodiment

[0190] Let (X) be the content (mass%) of magnetic particles (C) relative to the total mass of the bonded magnet mixture.

[0191] The specific surface area (m²) of magnetic particles (C) 2 / g) set to (Y),

[0192] When the content (mass%) of the curing agent (D) with an imidazole structure relative to the total mass of the bonded magnet mixture is set as (Z),

[0193] (X), (Y) and (Z) preferably satisfy the following equation (γ).

[0194] 0.000010≤(Z) / (X)×(Y)≤0.30…(γ)

[0195] By satisfying the above configuration, the bonding strength near the boundary between the magnetic particles and the resin composition is improved, which further enhances the mechanical strength of the bonded magnet. Furthermore, it can further suppress property changes caused by heating during the molding of the bonded magnet.

[0196] As described above, the imidazole-structured curing agent (D) of this embodiment interacts with the surface of the magnetic particles during heating, selectively increasing the concentration of the imidazole-structured curing agent (D) near the surface of the magnetic particles. Therefore, the content of the curing agent (D) relative to the total mass of the mixture is preferably adjusted to correspond to the surface area of ​​the magnetic particles. As a result, the interaction between the imidazole-structured curing agent (D) and the surface of the magnetic particles can be effectively exhibited.

[0197] The value of (X)×(Y) in formula (γ) is an index representing the specific surface area occupied by magnetic particles in the mixture. The larger the value, the larger the surface area of ​​magnetic particles in the mixture.

[0198] Furthermore, the value of (Z) / (X)×(Y) in formula (γ) is an indicator representing the ratio of the specific surface area of ​​the magnetic particles to the content of the curing agent (D) with an imidazole structure. By controlling (Z) / (X)×(Y) within a specific range, it is possible to maintain the overall curing strength of the bonded magnet while significantly increasing the crosslinking density near the surface of the metal-containing particles (magnetic particles). As a result, the mechanical strength and resistance to damp heat of the bonded magnet are improved.

[0199] In this embodiment, from the viewpoint of mechanical strength and resistance to damp heat, the value of (Z) / (X)×(Y) in formula (γ) is more preferably 0.000050≤(Z) / (X)×(Y)≤0.10, further preferably 0.00010≤(Z) / (X)×(Y)≤0.050, further preferably 0.00020≤(Z) / (X)×(Y)≤0.030, and even more preferably 0.00030≤(Z) / (X)×(Y)≤0.050.

[0200] As a method for controlling the value of (Z) / (X)×(Y), it can be adjusted by arbitrarily changing the values ​​of (X), (Y) and (Z).

[0201] <Compound (E) represented by formula (3)>

[0202] The mixture in this embodiment preferably contains the compound (E) represented by formula (3).

[0203]

[0204] In formula (1), R1 to R8 are each selected from the group consisting of hydrogen, alkyl (preferably alkyl with 1 to 50 carbon atoms), aromatic group, substituent containing heteroatoms, and substituent containing halogen atoms. R1 to R8 may be the same or different. In addition, at least two of R4 to R8 may be selected to form a ring and form a fused ring with the adjacent benzene ring.

[0205] By achieving the above-mentioned composition through the mixture, the adhesion between the metal element particles and the resin composition is improved, which further enhances the mechanical strength of the bonded magnet. Additionally, it also improves the resistance of the bonded magnet to damp heat.

[0206] The compounds represented by formula (3) above are not particularly limited, and examples include 3-phenoxy-1,2-propanediol, 3-phenoxy-1,3-propanediol, cresol glycerol ether (3-(2-methylphenoxy)-1,2-propanediol), guaiacol ether (3-(2-methoxyphenoxy)propane-1,2-diol), compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of biphenyl-type epoxy resin, compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of stilbene-type epoxy resin, compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of diphenylmethane-type epoxy resin, and compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of sulfur-containing epoxy resin. Compounds with a diol structure, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of phenolic varnish-type epoxy resins, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of phenolic varnish-type epoxy resins such as cresol and naphthol, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of dicyclopentadiene-type epoxy resins, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of salicylaldehyde-type epoxy resins such as salicylaldehyde-type varnish-type epoxy resins, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of copolymerized epoxy resins of naphthol and phenol, and aralkyl-type phenolic resins. Compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of epoxides; compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of bisphenol-type epoxy resins; compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of glycidyl ether-type epoxy resins of alcohols; compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of glycidyl ether-type epoxy resins modified with p-xylene and / or m-xylene; compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of glycidyl ether-type epoxy resins modified with terpenes; and compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy group of cyclopentadiene-type epoxy resins. Compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy groups of glycidyl ether type epoxy resins modified with polycyclic aromatic rings, compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy groups of glycidyl ether type epoxy resins containing naphthalene rings, compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy groups of glycidyl ester type epoxy resins, compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy groups of glycidyl or methyl glycidyl epoxy resins, compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy groups of alicyclic epoxy resins, and compounds with a 1,2-propanediol structure generated by ring-opening the terminal epoxy groups of halogenated phenolic varnish type epoxy resins.Compounds with a 2-propanediol structure, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of hydroquinone-type epoxy resins, compounds with a 1,2-propanediol structure formed by ring-opening of the terminal epoxy groups of trimethylolpropane-type epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracetic acid such as peracetic acid, etc.

[0207] From the viewpoint of achieving good compatibility with epoxy resin (A) and obtaining a uniform resin composition, it is preferable to include at least one compound selected from the group consisting of compounds having a 1,2-propanediol structure obtained by ring-opening the terminal epoxy groups of biphenyl-type epoxy resins, compounds having a 1,2-propanediol structure obtained by ring-opening the terminal epoxy groups of o-cresol phenolic varnish-type epoxy resins, compounds having a 1,2-propanediol structure obtained by ring-opening the terminal epoxy groups of phenolic varnish-type epoxy resins, compounds having a 1,2-propanediol structure obtained by ring-opening the terminal epoxy groups of salicylaldehyde phenolic varnish-type epoxy resins, and compounds having a 1,2-propanediol structure obtained by ring-opening the terminal epoxy groups of naphthol phenolic varnish-type epoxy resins. These compounds may be used alone or in combination of two or more.

[0208] The content of the compound represented by formula (3) relative to the total mass of epoxy resin (A) is preferably 0.00001% by mass or more, more preferably 0.0001% by mass or more, and even more preferably 0.001% by mass or more. Furthermore, the content of formula (3) relative to the total mass of epoxy resin (A) is preferably less than 20% by mass, more preferably less than 15% by mass, even more preferably less than 10% by mass, particularly preferably less than 8% by mass, even more preferably less than 7% by mass, even more preferably less than 6% by mass, even more preferably less than 5% by mass, very particularly preferably less than 3% by mass, and even more particularly preferably less than 2% by mass. The mixture of this embodiment, by containing 0.00001% by mass or more of the compound represented by formula (3), can further improve the mechanical strength and resistance to damp heat of the bonded magnet.

[0209] <Ketone compound (F)>

[0210] The mixture in this embodiment preferably contains a ketone compound (F). The mixture satisfies the above-described configuration, thereby improving the adhesion between the metal element particles and the resin composition, and further enhancing the mechanical strength and resistance to damp heat of the bonded magnet.

[0211] From the viewpoint of the Tg of the bonded magnet, the content of the ketone compound (F) relative to the total mass of the mixture is preferably less than 5.0% by mass, more preferably less than 1.0% by mass, and even more preferably less than 0.5% by mass. Furthermore, from the viewpoint of the resistance to damp heat of the bonded magnet, the content is preferably greater than 0.0001% by mass, more preferably greater than 0.0005% by mass, and even more preferably greater than 0.001% by mass, relative to the total mass of the mixture.

[0212] Examples of ketone compounds include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, acetophenone, and propylene glycol monomethyl ether acetate.

[0213] Lubricant

[0214] The mixture in this embodiment may contain a lubricant. By including a lubricant in the mixture, the fluidity and formability of the mixture are improved, as is its release properties. As a result, the shape and dimensional accuracy of the bonded magnet are improved, and structural defects in the bonded magnet are more easily suppressed.

[0215] Lubricants may be, for example, at least one selected from the group consisting of saturated fatty acids, saturated fatty acid salts, and saturated fatty acid esters. Waxes may be, for example, selected from lauric acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, arachidic acid, dodecanoic acid, behenic acid, tetracosanoic acid, wax acid, lignite, beeswax acid, calcium laurate, calcium myristicate, calcium pentadecanoate, calcium palmitate, calcium heptadecanoate, calcium stearate, calcium arachidate, calcium dodecanoate, calcium behenicate, calcium tetracosanoate, calcium wax acid, calcium lignite, calcium beeswax acid, barium laurate, etc. The mixture comprises at least one of the following groups: barium myristate, barium pentadecanoate, barium palmitate, barium heptadecanate, barium stearate, barium arachidate, barium dodecanoate, barium behenate, barium ceramide, barium ceramide, barium lignite, barium beeswax, laurate, myristate, pentadecanoate, palmitate, heptadecanate, stearate, arachidate, dodecanoate, behenate, tetracosinate, ceramide, lignite, and beeswax. The mixture may also contain waxes other than those listed above. For example, the wax may be selected from the group consisting of magnesium salts of the aforementioned saturated fatty acids, aluminum salts of the aforementioned saturated fatty acids, 12-hydroxystearic acid, calcium ricinoleate, stearamide, oleamide, erucamide, betaine, palmitamide, laurylamide, hydroxystearamide, methylene distearate, ethylene distearate, ethylene bislaurate, distearate adipamide, ethylene dioleate, dioleate adipamide, N-stearate stearamide, N-oleate stearamide, N-stearate erucamide, hydroxymethylstearamide, hydroxymethyl betaine, ethylene glycol, stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, silicone oil, silicone grease, fluorinated oil, fluorinated grease, fluorinated resin powder, paraffin wax, polyethylene wax, amide wax, polypropylene wax, ester wax, carnauba wax, and microcrystalline wax. The mixture may contain one of the aforementioned lubricants. The mixture may contain a variety of the lubricants mentioned above.

[0216] Lubricants can also be mixed into the mixture, or the dispersion of the internal lubricant can be applied to the inner wall of the mold (the wall that contacts the punch) during mixing.

[0217] <Coupled Agent>

[0218] The mixture in this embodiment may contain a coupling agent. By including a coupling agent, the adhesion between the resin composition and the surface of the metal-containing particles can be further improved, and the strength of the bonded magnet can be further improved.

[0219] Examples of coupling agents include: coupling agents of silane compounds such as epoxy silanes, mercaptosilanes, aminosilanes, alkylsilanes, ureosilanes and vinylsilanes, coupling agents of titanium compounds, coupling agents of aluminum chelates, coupling agents of aluminum / zirconium compounds, etc.

[0220] <Flow aids>

[0221] The mixture in this embodiment may contain inorganic filler as a flow aid. The inorganic filler may consist of one type of particle. The inorganic filler may be a combination of two or more types of particles.

[0222] The average particle size (D50) of the inorganic filler is preferably 1 μm or less, more preferably 500 nm or less, and even more preferably 100 nm or less. This improves the space-filling ratio of the bonded magnet.

[0223] Inorganic fillers can include, for example, inorganic microparticles such as silica, alumina, calcium carbonate, kaolin, titanium dioxide, barium sulfate, zinc oxide, aluminum hydroxide, magnesium hydroxide, talc, and mica.

[0224] Flame retardants

[0225] The mixture of this embodiment may contain a flame retardant. By containing a flame retardant, the fire resistance of the mixture can be improved. From the viewpoints of environmental safety, recyclability, processability, and low cost, the flame retardant is preferably at least one selected from the group consisting of brominated flame retardants, phosphorus-based flame retardants, hydrated metal compound flame retardants, organosilicon flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics.

[0226] <Organic Solvents (G)>

[0227] In the process of manufacturing the mixture, a varnish is prepared by dissolving the resin composition in an organic solvent (G), and this varnish is applied to the surface of each metal-containing particle constituting the metal-containing particle, thereby obtaining a homogeneous mixture. The organic solvent (G) is not limited to any solvent capable of dissolving the resin composition. For example, the organic solvent (G) can be at least one solvent selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, and xylene. Considering workability, the organic solvent (G) is preferably liquid at room temperature, and its boiling point is preferably 60°C or higher and 150°C or lower. Acetone and methyl ethyl ketone are preferred examples of such solvents.

[0228] Varnish

[0229] The varnish of this embodiment comprises an epoxy resin (A), a curing agent (D) having an imidazole structure, a curing agent (B) different from the curing agent having an imidazole structure, and an organic solvent (G). The varnish of this embodiment can be used for bonding magnets or in the process of manufacturing the mixture described later.

[0230] <Methods for preparing mixtures>

[0231] The method for manufacturing the mixture in this embodiment is not particularly limited. For example, methods for mixing resin compositions above the melting point (hereinafter referred to as "melt mixing") and methods for dissolving and mixing resin compositions in a solvent (hereinafter referred to as "dissolution mixing") can be cited.

[0232] Melt mixing can be carried out using the following methods.

[0233] A mixed powder of the raw materials (epoxy resin, metal-containing particles, a curing agent (D) with an imidazole structure, a curing agent (B) different from the curing agent with an imidazole structure, and other additives) can be obtained by thoroughly mixing the raw materials in a mixer. The resulting mixed powder of the raw materials is heated and mixed at a temperature above the softening temperature of the resin composition, and the solid matter is appropriately pulverized to obtain the mixture.

[0234] The heating and mixing temperature also depends on the type and amount of resin composition, preferably 40°C or higher and 140°C or lower, more preferably 60°C or higher and 120°C or lower. By heating and mixing within the above temperature range, the curing reaction of the resin composition can be suppressed and the dispersibility of the materials in the mixture can be improved.

[0235] There are no particular limitations on the mixing device; for example, a heated mixer can be used. In this case, the material dispersion can be controlled by changing the amount of raw materials added to the mixture.

[0236] Dissolution and mixing can be carried out using the following methods.

[0237] A solution of the resin composition is obtained by dissolving raw materials such as epoxy resin, a curing agent (D) having an imidazole structure, and a curing agent (B) different from the curing agent having an imidazole structure in an organic solvent (G). Metal-containing particles are added to the resin composition solution to disperse the magnetic particles. The organic solvent (G) is then removed from the solution containing the metal-containing particles and the resin composition by vacuum distillation and drying. As a result, the surface of the metal-containing particles is covered by the resin composition, yielding a mixture containing the metal-containing particles and the resin composition.

[0238] In the process of removing organic solvent (G) from a solution containing metal element particles and a resin composition, it is preferable to use an evaporator to remove the organic solvent (G) by vacuum distillation at room temperature while stirring the solution. The solid material obtained by vacuum distillation is further dried using a vacuum dryer or similar equipment, and then appropriately pulverized to obtain a mixture. Alternatively, instead of vacuum distillation, atmospheric distillation can be performed while stirring the solution using a kneader or similar equipment. As a drying method for the solid material obtained by distillation, the solid material can be dried, for example, by heating it to a temperature below 80°C, preferably below 60°C, and more preferably below 40°C.

[0239] <Manufacturing Methods of Bonded Magnets>

[0240] A molded body is obtained by compressing the mixture filled into a mold. Higher molding pressure results in higher density of the bonded magnet, but also makes the magnetic particles more prone to breakage. The molding pressure can be arbitrarily set according to the characteristics of the mixture and the bonded magnet.

[0241] By heat treating the molded body, the resin composition in the molded body is cured, and the magnetic particles in the molded body are bonded together by the cured resin composition, thus obtaining a bonded magnet. The heat treatment temperature of the molded body is preferably set to a temperature at which the resin composition is fully cured. Furthermore, from the viewpoint of suppressing oxidation of the surface of the magnetic particles, low-temperature curing and short-time curing are preferred. The curing temperature is preferably, for example, below 200°C, more preferably below 180°C, and even more preferably below 150°C. The curing time is preferably, for example, below 120 minutes, more preferably below 60 minutes, and even more preferably below 30 minutes.

[0242] When orienting magnetic particles, a magnetic field can be applied before molding compression, during molding compression, and during the heat treatment of the molded body. When applying a magnetic field during the heat treatment of the molded body, for example, by heating the molded body to 100°C to soften the resin composition, the orientation rate of the magnetic particles can be further increased. After magnetic field orientation, the compression pressure can be increased until the molded body reaches a specified density.

[0243] Example

[0244] The present invention will be described in more detail below with specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.

[0245] It should be noted that, unless otherwise specified, "parts" and "%" are the quality standards below.

[0246] [Bonded Magnet Mixture]

[0247] (Epoxy resin (A-1)~(A-5))

[0248] The epoxy resins (A-1) to (A-5) used in each embodiment and comparative example are shown in Table 1.

[0249] [Table 1]

[0250] (Curing agent (B-1)~(B-2))

[0251] Table 2 shows the curing agents (B-1) to (B-2) used in each embodiment and comparative example.

[0252] [Table 2]

[0253] (Contains metal element particles (C-1)~(C-2))

[0254] Table 3 shows the metal-containing particles (C-1) to (C-2) used in each embodiment and comparative example.

[0255] [Table 3]

[0256]

[0257] (filler particles (R-1)~(R-2))

[0258] The filler particles (R-1) to (R-2) used in each comparative example are shown in Table 4.

[0259] [Table 4]

[0260]

[0261] (Curing agent (D-1)~(D-4))

[0262] Table 5 shows the curing agents (D-1) to (D-4) used in each embodiment and comparative example.

[0263] [Table 5]

[0264]

[0265] (Curing agent (D'-1)~(D'-12))

[0266] The curing agents (D'-1) to (D'-12) used in each comparative example are shown in Table 6.

[0267] [Table 6]

[0268]

[0269] (The compounds (E-1) to (E-2) represented by formula (3))

[0270] The compounds (E-1) to (E-2) represented by formula (3) used in the various examples and comparative examples are shown in Table 7.

[0271] [Table 7]

[0272]

[0273] [Preparation of the Bonded Magnet Mixture]

[0274] (Example 1)

[0275] 2.0 g of epoxy resin (A-1), 1.49 g of curing agent (B-1), 0.06 g of curing agent (D-1) and 20.0 g of methyl ethyl ketone were mixed in a 300 mL round-bottom flask and stirred for 30 minutes to prepare a solution of the resin composition (resin solution).

[0276] 13.6 g of metal element particles (C-1) and 54.4 g of metal element particles (C-2) were added to a flask containing the above resin solution, and the mixture was stirred at 25°C for 30 minutes. Next, the pressure in the evaporator was reduced to below 0.1 MPa to distill off the methyl ethyl ketone (MEK) in the flask. During the distillation process, to ensure uniform removal of MEK, the pressure in the flask was repeatedly reduced, the pressure was restored to atmospheric pressure, and the aggregated contents in the flask were disassembled several times. After distillation to remove MEK, the mixture of the resin composition and magnetic particles was recovered from the flask and spread on a flat plate. The following steps were repeated several times for the mixture on the plate: vacuum drying at room temperature using a vacuum dryer, restoring the vacuum dryer to atmospheric pressure, and disassembling the aggregates. Drying was stopped when the MEK content in the mixture reached 0.05% by mass, yielding mixture (CPD-1).

[0277] The following evaluation was conducted using the above resin solution and the resulting mixture.

[0278] (Examples 2-7, Examples 9-14, Examples 16-18, Comparative Examples 1-14)

[0279] By changing the formulation to the one described in Table 8, bonded magnet mixtures (CPD-2) to (CPD-7), (CPD-9) to (CPD-14), (CPD-16) to (CPD-17) and (CPD-18) to (CPD-32) were obtained in the same manner as in Example 1.

[0280] The evaluation was conducted in the same manner as in Example 1.

[0281] (Example 8)

[0282] The formulation was changed to the formulation described in Table 8, and drying was stopped when the content of methyl ethyl ketone in the mixture reached 0.2% by mass. Otherwise, the mixture (CPD-8) was obtained in the same manner as in Example 1.

[0283] The evaluation was conducted in the same manner as in Example 1.

[0284] (Example 15)

[0285] 2.0g of epoxy resin (A-1), 1.49g of curing agent (B-1), 0.06g of curing agent (D-1), 13.6g of metal element particles (C-1), and 54.4g of magnetic particles (C-2) were mixed in a mixer to prepare a mixture of raw materials.

[0286] Using a low-speed rotating (10 rpm) kneader, the above raw material mixture is melt-mixed at 110°C for 1 minute, and the resulting melt mixture is broken up to obtain the mixture (CPD-8).

[0287] The evaluation was conducted in the same manner as in Example 1.

[0288] [evaluate]

[0289] (Specific surface area of ​​particles containing metallic elements)

[0290] The specific surface area was measured using a fully automated BET specific surface area measuring device HM model-1201 manufactured by Mounttech Co., Ltd., with a N2 / He mixture of 30 / 70 (volume ratio) as the adsorbed gas.

[0291] It should be noted that when there are two or more metal-containing particles, the specific surface area is calculated based on the specific surface area and content ratio of each metal-containing particle, using the average value of the entire metal-containing particle group.

[0292] (Varnish storage stability)

[0293] The viscosity (initial viscosity) of a freshly prepared resin solution containing epoxy resin, a curing agent (D) with an imidazole structure, and a curing agent (B) different from the curing agent with an imidazole structure was measured at room temperature (25°C). The viscosity of the resin solution after being stored at 25°C for 2 weeks was also measured. The thickening ratio of the varnish was calculated using the following mathematical formula (1). In addition, cases where the resin solution is partially or completely cured after storage and the viscosity cannot be measured are recorded as cured.

[0294] Varnish thickening ratio (times) = Viscosity after storage at 25℃ for 2 weeks / Initial viscosity ... Mathematical formula (1)

[0295] Set grades A and B as qualified.

[0296] <Evaluation Criteria>

[0297] A: The thickening ratio of the varnish is greater than 1.0 and less than 1.1.

[0298] B: The thickening ratio of the varnish is more than 1.1 times and less than 1.3 times.

[0299] C: The thickening ratio of the varnish is more than 1.3 times and less than 1.5 times.

[0300] D: The varnish thickening ratio is 1.5 times or more.

[0301] (Mechanical strength of bonded magnets)

[0302] The adhesive magnet mixture is filled into a molding die and compressed using a hydraulic molding machine at a molding pressure of 150 MPa for 1 minute to obtain a compression molded body of 4 mm × 4 mm × 4 mm. The resulting compression molded body is then heated in a constant temperature bath at 150 °C for 30 minutes to produce the adhesive magnet molded body.

[0303] The resulting bonded magnet molded body was placed in an Autograph AGS-H 5kN (manufactured by Shimadzu Corporation) and a compressive pressure was applied at a crosshead speed of 1.0 mm / min. The maximum compressive pressure at which the bonded magnet molded body broke was taken as the mechanical strength (MPa). The mechanical strength was measured at 25°C.

[0304] Set grades A and B as qualified.

[0305] <Evaluation Criteria>

[0306] A: Mechanical strength is above 120MPa.

[0307] B: Mechanical strength is above 100MPa and less than 120MPa.

[0308] C: Mechanical strength is above 80MPa and less than 100MPa.

[0309] D: Mechanical strength is less than 80MPa.

[0310] (Changes in properties caused by heating during the molding of bonded magnets)

[0311] The bonded magnet mixture was heated in a constant temperature bath at 100°C for 30 minutes (an example of the conditions for magnetic particle orientation). After heating, the mechanical strength of the bonded magnet mixture was measured. Based on the mechanical strength before and after heating, the mechanical strength retention rate was calculated by the following mathematical formula (2) as an indicator of the change in properties caused by heating during the molding of the bonded magnet.

[0312] Mechanical strength retention rate = Mechanical strength of the mixture after heating at 100℃ for 30 minutes / Mechanical strength × 100... Mathematical formula (2)

[0313] Set grades A and B as qualified.

[0314] <Evaluation Criteria>

[0315] A: The mechanical strength retention rate is above 70.0%.

[0316] B: Mechanical strength retention rate is above 60.0% and below 70.0%.

[0317] C: Mechanical strength retention rate is above 50.0% and below 60.0%.

[0318] D: Mechanical strength retention rate is less than 50.0%.

[0319] (Resistance to damp heat of bonded magnets)

[0320] The bonded magnet molded body was placed in a high temperature and high humidity environment (temperature 85℃, humidity 85%) for 7 days, and the mechanical strength was measured using the bonded magnet molded body after placement. The manufacturing method of the bonded magnet molded body is the same as the manufacturing method described in the evaluation method of mechanical strength. Based on the mechanical strength before and after placement, the mechanical strength retention rate was calculated by the following mathematical formula (3) as an indicator of resistance to damp heat.

[0321] Mechanical strength retention rate (%) = Mechanical strength after 7 days of placement in a high temperature and high humidity environment / Mechanical strength × 100... Mathematical formula (3)

[0322] Set grades A and B as qualified.

[0323] <Evaluation Criteria>

[0324] A: The mechanical strength retention rate is above 85.0%.

[0325] B: Mechanical strength retention rate is above 75.0% and below 85.0%.

[0326] C: Mechanical strength retention rate is above 65.0% and below 75.0%.

[0327] D: Mechanical strength retention rate is less than 65.0%.

[0328] The compositions of the mixtures (CPD-1 to CPD-17 and CPD-32) of [Examples 1 to 18] and the mixtures (CPD-18 to CPD-31) of [Comparative Examples 1 to 14] are shown in Table 8 below, and the evaluation results are shown in Table 9 below.

[0329] [Table 8]

[0330]

[0331] [Table 9]

[0332]

[0333] As shown in Tables 8 and 9, the examples of adhesive magnet mixtures comprising epoxy resin (A), metal element particles (C), and a curing agent (D) having an imidazole structure, wherein the curing agent (D) having an imidazole structure comprises compounds represented by formula (1) and / or compounds represented by formula (2), have a long service life in the manufacturing process, minimal changes in properties due to heating during the molding of the adhesive magnet, and exhibit high mechanical strength when the thermosetting resin is cured at low temperatures.

[0334] On the other hand, in the comparative example that does not contain metal element particles (C) and a specified curing agent (D) with an imidazole structure, there is a long usable time difference in the manufacturing process, a large change in properties caused by heating during the molding of the bonded magnet, and poor mechanical strength when the thermosetting resin is cured under low temperature conditions.

[0335] Industrial availability

[0336] The bonding magnet mixture of this embodiment is industrially applicable as a material for various bonding magnets.

Claims

1. A mixture comprising an epoxy resin (A), metal-containing particles (C), and a curing agent (D) having an imidazole structure. The curing agent (D) having an imidazole structure comprises a compound represented by formula (1) and / or a compound represented by formula (2). In formulas (1) and (2), R1 and R2 are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, halogen atom, alkyl group with 1 to 20 carbon atoms with optional substituents, and cycloalkyl group with 6 to 20 carbon atoms with optional substituents; R1 and R2 can be chosen to be the same or different, and R1 and R2 can be bonded together to form a fused ring that is not aromatic; X is any one of the following groups: hydrogen atom, alkyl group having 1 to 20 carbon atoms with substituents, alkenyl group having 2 to 20 carbon atoms with substituents, aralkyl group having 7 to 20 carbon atoms with substituents, and heteroarylalkyl group having 4 to 20 carbon atoms with substituents. Y and Z are each independently selected from the group consisting of hydrogen atom, halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group with 1 to 20 carbon atoms having a substituent, alkoxy group with 1 to 20 carbon atoms having a substituent, alkenyl group with 2 to 20 carbon atoms having a substituent, aryl group with 6 to 20 carbon atoms having a substituent, aryloxy group with 6 to 20 carbon atoms having a substituent, and acyl group with 1 to 20 carbon atoms having a substituent; Y and Z are each selected to be the same or different, and two or more Ys or two or more Zs are each selected to be bonded to form a monocyclic or fused ring; m and n are each independently an integer from 1 to 4.

2. The mixture according to claim 1, wherein, In the curing agent (D) having an imidazole structure, Y and Z are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, alkoxy group with 1 to 20 carbon atoms without substituents, alkyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, alkoxy group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, aryl group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, aryloxy group with 6 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents, and acyl group with 1 to 20 carbon atoms having hydroxyl and / or carboxyl groups as substituents.

3. The mixture according to claim 1 or 2, wherein, In the curing agent (D) having an imidazole structure, The compound represented by formula (1) is any one selected from the group consisting of 2-(2-hydroxyphenyl)imidazolium, 2-(2-hydroxyphenyl)-4-methylimidazolium, 2-(2-hydroxyphenyl)-5-methylimidazolium, 4-ethyl-(2-hydroxyphenyl)-5-methylimidazolium, (2-hydroxyphenyl)-4-isopropyl-5-methylimidazolium, 4-butyl-(2-hydroxyphenyl)-5-methylimidazolium, 2-(2-hydroxy-3-methoxyphenyl)imidazolium and 2-(2-hydroxy-5-methoxyphenyl)imidazolium; And / or, The compound represented by formula (2) is any one selected from the group consisting of 2-(2-hydroxyphenyl)benzimidazole, 2-(2-hydroxy-3-methoxyphenyl)benzimidazole, 2-(2-hydroxy-5-methoxyphenyl)benzimidazole, 2-(1-hydroxynaphth-2-yl)benzimidazole, 2-(2-hydroxynaphth-1-yl)benzimidazole and 2-(2-hydroxyphenyl)benzimidazole-6-carboxylic acid.

4. The mixture according to claim 1 or 2, further comprising a curing agent (B) different from the curing agent having an imidazole structure.

5. The mixture according to claim 4, wherein, Curing agent (B), which differs from the curing agent having an imidazole structure, comprises a curing agent that is solid at 25°C. The content of the curing agent that is solid at 25°C is 50% by mass or more relative to the total amount of curing agent.

6. The mixture according to claim 1 or 2, wherein, The metal-containing particles (C) are magnetic particles.

7. The mixture according to claim 6, wherein, The magnetic particles are rare earth magnetic particles.

8. The mixture according to claim 6, wherein, The content of the magnetic particles is more than 70% by mass and less than 99.5% by mass relative to the total mass of the mixture.

9. The mixture according to claim 6, wherein, The specific surface area of ​​the magnetic particles is 0.005 m². 2 / g or more and 5.0m 2 / g or less.

10. The mixture according to claim 6, wherein, Let (X) be the content of the magnetic particles relative to the total mass of the mixture. Let the specific surface area of ​​the magnetic particles be (Y). When the content of the curing agent (D) with the imidazole structure relative to the total mass of the mixture is set as (Z), (X), (Y), and (Z) satisfy the following equation (γ), 0.000010≤(Z) / (X)×(Y)≤0.30…(γ); The content of the magnetic particles relative to the total mass of the mixture is expressed in terms of mass%, and the content of the curing agent (D) with an imidazole structure relative to the total mass of the mixture is expressed in terms of mass%.

11. The mixture according to claim 1, wherein, The epoxy resin (A) comprises a portion of the structure represented by the following formula (A1). In formula (A1), R1 to R3 are each independently a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a heteroatom, or a substituent containing a halogen atom. At least one of R1 to R3 contains a reactive group that reacts with the curing agent (D) having the imidazole structure. R1 to R3 may be the same as or different from each other.

12. The mixture according to claim 1, wherein, The epoxy resin (A) comprises a portion of the structure represented by the following formula (A2). In equation (A2), R 1 R 2 It is an alkylene group having 1 to 12 carbon atoms, where m and n are each an independent integer greater than or equal to 1, and G 1 and G 2 G is selected from the group consisting of hydrogen atoms, alkyl groups, aromatic groups, substituents containing heteroatoms, and substituents containing halogen atoms. 1 and G 2 They can choose to be the same or different from each other.

13. The mixture according to claim 1 or 2, wherein, The epoxy resin (A) comprises an epoxy resin that is solid at 25°C. The content of the epoxy resin that is solid at 25°C is 50% by mass or more relative to the total amount of epoxy resin.

14. The mixture according to claim 1 or 2, further comprising compound (E) represented by formula (3) below, In formula (3), R1 to R8 are each independently selected from the group consisting of hydrogen, alkyl, aromatic groups, substituents containing heteroatoms and substituents containing halogen atoms. R1 to R8 may be the same or different. Furthermore, at least two of R4 to R8 may be selected to form a ring and form a fused ring with the adjacent benzene ring.

15. A varnish comprising an epoxy resin (A), a curing agent (D) having an imidazole structure, a curing agent (B) different from the curing agent having an imidazole structure, and an organic solvent (G). The curing agent (D) having an imidazole structure comprises a compound represented by formula (1) and / or a compound represented by formula (2). In formulas (1) and (2), R1 and R2 are each independently selected from the group consisting of hydrogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, halogen atom, alkyl group with 1 to 20 carbon atoms with optional substituents, and cycloalkyl group with 6 to 20 carbon atoms with optional substituents; R1 and R2 can be chosen to be the same or different, and R1 and R2 can be bonded together to form a fused ring that is not aromatic; X is any one of the following groups: hydrogen atom, alkyl group having 1 to 20 carbon atoms with substituents, alkenyl group having 2 to 20 carbon atoms with substituents, aralkyl group having 7 to 20 carbon atoms with substituents, and heteroarylalkyl group having 4 to 20 carbon atoms with substituents. Y and Z are each independently selected from the group consisting of hydrogen atom, halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group with 1 to 20 carbon atoms having a substituent, alkoxy group with 1 to 20 carbon atoms having a substituent, alkenyl group with 2 to 20 carbon atoms having a substituent, aryl group with 6 to 20 carbon atoms having a substituent, aryloxy group with 6 to 20 carbon atoms having a substituent, and acyl group with 1 to 20 carbon atoms having a substituent; Y and Z are each selected to be the same or different, and two or more Ys or two or more Zs are each selected to be bonded to form a monocyclic or fused ring; m and n are each independently an integer from 1 to 4.

16. A bonded magnet, which is formed and cured by molding the mixture according to any one of claims 1 to 16.

17. A motor comprising the bonded magnet of claim 16.

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