Compound, varnish, bond magnet, and motor

Abstract

The compound contains an epoxy resin (A), magnetic particles (C), and a curing agent (D). In differential scanning calorimetry of the compound, (X) and (Y) satisfy formula (1) and formula (2), where (X) is a heating vertex temperature of a heat quantity curve at a temperature increase rate of 2°C / min of the compound, and (Y) is a heating vertex temperature of a heat quantity curve at a temperature increase rate of 2°C / min after the compound is pressurized at 200 MPa for 5 minutes. 100 ≤ (X) ≤ 200 … (1) (X) - (Y) ≥ 3 … (2)

Description

Compounds, varnishes, bonded magnets and motors

[0001] The present invention relates to a compound, a varnish, a bonded magnet, and a motor.

[0002] A bonded magnet is a molded body made by mixing magnetic particles with a binder such as a resin component and processing it into a specific shape. Because bonded magnets contain resin components, they have a high degree of freedom in shape and are more moldable than sintered magnets, so they are increasingly being used in motor applications such as automobiles, general home appliances, communication and audio equipment, medical equipment, and general industrial equipment. However, these motors are expected to have higher rotation speeds in anticipation of higher output, and bonded magnets, which are subject to strong centrifugal forces, tend to require high fixing strength to metal components.

[0003] Patent Document 1 discloses a resin compound for bonded magnets containing an epoxy resin, a curing agent, a curing accelerator, and magnetic powder, in which the accelerator has a borane structure and a borate structure, resulting in a resin compound for bonded magnets with excellent storage stability and mechanical strength.

[0004] Patent No. 6606908

[0005] Bonded magnets are molded by applying heat and pressure to a composite material (compound) obtained by mixing magnetic particles with binders such as resin components. Compression molding compounds contain thermosetting resins, which provide excellent heat resistance. However, the curing reaction of the resin components progresses even during storage, often resulting in storage stability issues. Furthermore, compression molding requires heating to accelerate the curing reaction of the thermosetting resin. However, the magnetic particles in the compound are sensitive to heat, and in a heated environment, their surfaces oxidize, resulting in a deterioration of their magnetic properties. Therefore, there is a demand for compounds that can maintain high bonding strength to metal components even when the thermosetting resin is reacted at low temperatures (e.g., below 150°C). In contrast, compounds containing curing accelerators having a borane structure and a borate structure as described in the above document have a certain effect on storage stability, but when the thermosetting resin is cured under lower temperature conditions, there is room for improvement in the fixing strength to the metal member.

[0006] The problem to be solved by the present invention is to provide a compound which has excellent storage stability and exhibits high fixing strength to metal members even when the thermosetting resin is subjected to a curing reaction under low temperature conditions.

[0007] As a result of extensive research into solving the above-mentioned problems, the inventors have discovered that the above-mentioned problems of the conventional technology can be solved by using a compound that contains an epoxy resin, magnetic particles, and a curing agent, and whose calorific curve obtained by differential scanning calorimetry satisfies a predetermined relationship, and have thus completed the present invention.

[0008] The present invention includes the following aspects. <1> A compound comprising an epoxy resin (A), magnetic particles (C), and a curing agent (D), wherein, in differential scanning calorimetry, (X) is the exothermic peak temperature of a calorimetry curve of the compound at a heating rate of 2°C / min, and (Y) is the exothermic peak temperature of the calorimetry curve of the compound at a heating rate of 2°C / min after pressurizing the compound at 200 MPa for 5 minutes, where (X) and (Y) satisfy the following formulas (1) and (2): 100≦(X)≦200 (1) (X)-(Y)≧3 (2) <2> The compound according to <1>, wherein the curing agent (D) comprises a capsule-type curing agent. <3> The compound according to <1> or <2>, wherein the content of the curing agent (D) is 0.1 parts by mass or more and 15.0 parts by mass or less per 100 parts by mass of the epoxy resin (A). <4> The compound according to <2> or <3>, wherein the core component of the curing agent (D) is solid. <5> The compound according to any one of <1> to <3>, wherein the curing agent (D) contains an amine-epoxy adduct. <6> The compound according to <5>, wherein the amine-epoxy adduct contains an adduct of an imidazole compound and a bisphenol A-type epoxy resin. <7> The compound according to any one of <1> to <6>, further containing a curing agent (B). <8> The compound according to <7>, wherein the curing agent (B) contains a curing agent that is solid at room temperature, and the content of the curing agent that is solid at room temperature is 50 mass% or more relative to the total amount of the curing agent (B). <9> The compound according to any one of <1> to <8>, wherein the epoxy resin (A) contains a structure represented by the following formula (A1):

[0009]

[0010] (In formula (A1), R １ ~R ３ 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 R １ ~R ３ At least one of the groups contains a reactive group with the curing agent (D), and R １ ~R ３may be the same or different.) <10> The compound according to any one of <1> to <9>, wherein the epoxy resin (A) contains a structure represented by the following formula (A2):

[0011]

[0012] (In formula (A2), R １ , R ２ is an alkyl group having 1 to 12 carbon atoms, and m and n are each independently an integer of 1 or more. １ and G ２ is one selected from the group consisting of a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom. １ and G ２ may be the same or different.)

[0013] <11> The compound according to any one of <1> to <10>, wherein the epoxy resin (A) contains an epoxy resin that is solid at room temperature, and the content of the epoxy resin that is solid at room temperature is 50 mass% or more relative to the total amount of the epoxy resin (A). <12> The compound according to any one of <1> to <11>, wherein the magnetic particles (C) are rare earth magnetic particles. <13> A compound comprising an epoxy resin (A), magnetic particles (C), and a curing agent (D), wherein the curing agent (D) is a capsule-type curing agent. <14> The compound according to <13>, further comprising a curing agent (B). <15> The compound according to <13> or <14>, wherein the core component of the curing agent (D) is solid, and the curing agent (D) contains an amine-epoxy adduct, and the amine-epoxy adduct contains an adduct of an imidazole compound and a bisphenol A-type epoxy resin. <16> A varnish comprising an epoxy resin (A), a curing agent (B), a curing agent (D), and an organic solvent (E), wherein the curing agent (D) comprises a capsule-type curing agent, the core component of the curing agent (D) is solid, and the curing agent (D) comprises an amine-epoxy adduct, the amine-epoxy adduct comprising an adduct of an imidazole compound and a bisphenol A-type epoxy resin. <17> A bonded magnet obtained by molding and curing the compound according to any one of <1> to <15>. <18> A motor comprising the bonded magnet according to <17>.

[0014] According to the present invention, it is possible to provide a compound which has excellent storage stability and exhibits high fixing strength to metal members even when the thermosetting resin is subjected to a curing reaction under low temperature conditions.

[0015] FIG. 1 shows a test piece for fixation strength.

[0016] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0017] Compound The compound of the present embodiment includes embodiment A and embodiment B. Each embodiment will be described below.

[0018] <Embodiment A> The compound of embodiment A is a compound containing an epoxy resin (A), magnetic particles (C), and a curing agent (D), wherein, in differential scanning calorimetry, when the exothermic peak temperature of the calorific curve of the compound at a heating rate of 2°C / min is (X), and the exothermic peak temperature of the calorific curve of the compound at a heating rate of 2°C / min after pressurizing the compound at 200 MPa for 5 minutes is (Y), (X) and (Y) satisfy the following formulas (1) and (2): 100≦(X)≦200 (1) (X)-(Y)≧3 (2)

[0019] The compound of embodiment A contains an epoxy resin (A), magnetic particles (C), and a curing agent (D). The mixture of the epoxy resin (A) and the curing agent (D) (hereinafter simply referred to as the "resin composition") undergoes a curing reaction upon heat treatment, and in addition to being strongly bonded to the magnetic particles (C), it also exhibits high fixing strength to metal members.

[0020] (Formula (1)) In the compound of embodiment A, when the exothermic peak temperature of the calorie curve at a temperature rise rate of 2°C / min in differential scanning calorimetry is defined as (X), (X) satisfies the following formula (1): 100≦(X)≦200 (1)

[0021] By satisfying the above-mentioned requirements, a compound can be obtained that has excellent storage stability and exhibits high fixing strength to metal members even when the thermosetting resin is cured under low-temperature conditions. The reason for this is considered as follows. The exothermic peak in differential scanning calorimetry is derived from the heat of reaction of the curing reaction of the resin composition due to heating of the compound. Furthermore, the exothermic peak temperature (X) can be regarded as an index indicating the reactivity of the resin composition. If the value of (X) is 100 or more, the curing reaction of the resin composition does not progress during storage of the compound (usually at 40°C or less), improving the storage stability of the compound. On the other hand, if the value of (X) is 200 or less, the resin composition cures sufficiently even when heated under low-temperature conditions (e.g., 150°C or less), improving the fixing strength to metal members. Therefore, the compound is required to satisfy formula (1). From the viewpoint of achieving both storage stability and fixing strength during low-temperature curing, the value of the exothermic peak temperature (X) is preferably 110≦(X)≦190, more preferably 120≦(X)≦180, and particularly preferably 130≦(X)≦170. Methods for controlling the exothermic peak temperature (X) include a method of adjusting the exothermic peak temperature (X) by changing the type and amount of the curing agent added.

[0022] (Formula (2)) In the compound of embodiment A, when the exothermic peak temperature of the calorific curve at a temperature rise rate of 2°C / min in differential scanning calorimetry is (X), and the exothermic peak temperature of the calorific curve at a temperature rise rate of 2°C / min after pressurizing the compound at 200 MPa for 5 minutes is (Y), (X) and (Y) satisfy the following formula (2): (X) - (Y) ≥ 3 (2)

[0023] By satisfying the above-mentioned constitution, a compound having excellent storage stability and exhibiting high fixing strength to metal members even when reacted with a thermosetting resin under low temperature conditions can be obtained. The reason for this is considered as follows.

[0024] The manufacturing process for bonded magnets using thermosetting resins proceeds in the following order: (1) preparation and storage of the compound, (2) compression molding of the compound, and (3) thermal curing of the molded body. By arbitrarily controlling the reactivity of the resin composition in each step, it is possible to achieve both high levels of storage stability and high-level fixing strength during low-temperature curing. Specifically, this can be achieved by suppressing the reactivity of the resin composition during (1) preparation and storage of the compound, and increasing the reactivity of the resin composition during (2) compression molding of the compound and (3) thermal curing of the molded body. One method for arbitrarily controlling the reactivity of the resin composition is to increase the reactivity of the resin composition by utilizing the pressure (usually 200 MPa or more) that the compound experiences in the mold cavity during (2) the compression molding step of the compound.

[0025] The value of (X) - (Y) in formula (2) is an index showing the change in reactivity of the resin composition before and after applying pressure to the compound at 200 MPa for 5 minutes, and a larger value indicates an improvement in the reactivity of the resin composition after applying pressure. Therefore, the compound of embodiment A is required to satisfy formula (2).

[0026] In embodiment A, from the viewpoint of achieving both storage stability and fixing strength during low-temperature curing, the value of (X)-(Y) in formula (2) is preferably (X)-(Y)≧5, more preferably (X)-(Y)≧7, and even more preferably (X)-(Y)≧10, when compared at the same added amount of magnetic particles.

[0027] As mentioned above, one method for controlling the value of (X)-(Y) is to use, for example, a capsule-type curing agent to improve reactivity when pressure is applied. The value can also be adjusted by the type of epoxy resin and curing agent; for example, the value tends to increase when solid components are included as the epoxy resin and curing agent. Additionally, the value tends to increase when the amount of magnetic particles added is increased.

[0028] <Epoxy Resin (A)> The compound of embodiment A contains an epoxy resin. Examples of the epoxy resin include, but are not limited to, biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-containing epoxy resins, novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and naphthol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins such as salicylaldehyde novolac-type epoxy resins, copolymer-type epoxy resins of naphthols and phenols, epoxidized products of aralkyl-type phenolic resins, bisphenol-type epoxy resins, glycidyl ether-type epoxy resins of alcohols, and glycidyl ethers of paraxylylene and / or metaxylylene-modified phenolic resins. Examples of epoxy resins include glycidyl ether type epoxy resins, glycidyl ether type epoxy resins of terpene-modified phenolic resins, cyclopentadiene type epoxy resins, glycidyl ether type epoxy resins of polycyclic aromatic ring-modified phenolic resins, glycidyl ether type epoxy resins of naphthalene ring-containing phenolic resins, glycidyl ester type epoxy resins, glycidyl or methylglycidyl type epoxy resins, alicyclic type epoxy resins, halogenated phenol novolac type epoxy resins, hydroquinone type epoxy resins, trimethylolpropane type epoxy resins, linear aliphatic epoxy resins obtained by oxidizing an olefin bond with a peracid such as peracetic acid, epoxy resins containing a structure represented by the following formula (A1), and epoxy resins containing a structure represented by the following formula (A2). These may be used alone or in combination of two or more.

[0029]

[0030] (In formula (A1), R １ ~R ３ 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 R １ ~R ３ At least one of the groups contains a reactive group with the curing agent (D), and R １ ~R ３ may be the same or different from each other.

[0031] (In formula (A2), R １ , R ２ is an alkyl group having 1 to 12 carbon atoms, and m and n are each independently an integer of 1 or more. １ and G ２ is one selected from the group consisting of a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom. １ and G ２ may be the same or different.)

[0032] From the viewpoint of increasing the mechanical strength of the bonded magnet, the epoxy resin preferably contains at least one selected from the group consisting of biphenyl-type epoxy resins, orthocresol novolac-type epoxy resins, phenol novolac-type epoxy resins, salicylic aldehyde novolac-type epoxy resins, naphthol novolac-type epoxy resins, epoxy resins containing a structure represented by the following formula (A1), and epoxy resins containing a structure represented by the following formula (A2).

[0033]

[0034] (In formula (A1), R １ ~R ３ 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 R １ ~R ３ At least one of the groups contains a reactive group with the curing agent (D), and R １ ~R ３ may be the same or different from each other.

[0035] (In formula (A2), R １ , R ２ is an alkyl group having 1 to 12 carbon atoms, and m and n are each independently an integer of 1 or more. １ and G ２ is one selected from the group consisting of a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom. １ and G ２may be the same or different.)

[0036] From the viewpoint of increasing the fixing strength to the metal member, the epoxy resin more preferably contains an epoxy resin containing a structure represented by the following formula (A1) or an epoxy resin containing a structure represented by the following formula (A2):

[0037]

[0038] (In formula (A1), R １ ~R ３ 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 R １ ~R ３ At least one of the groups contains a reactive group with the curing agent (D), and R １ ~R ３ may be the same or different from each other.

[0039] (In formula (A2), R １ , R ２ is an alkyl group having 1 to 12 carbon atoms, and m and n are each independently an integer of 1 or more. １ and G ２ is one selected from the group consisting of a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom. １ and G ２ may be the same or different.)

[0040] From the viewpoint of enhancing the fluidity of the compound, the epoxy resin preferably contains at least one crystalline epoxy resin. Crystalline epoxy resins have a melting point and do not soften at temperatures below the melting point, thereby exhibiting excellent fluidity.

[0041] Examples of crystalline epoxy resins include hydroquinone type epoxy resins, bisphenol type epoxy resins, thioether type epoxy resins, and biphenyl type epoxy resins. Commercially available crystalline epoxy resins include Epicron 860, Epicron 1050, Epicron 1055, Epicron 2050, Epicron 3050, Epicron 4050, Epicron 7050, Epicron HM-091, Epicron HM-101, Epicron N-730A, Epicron N-740, Epicron N-770, and Epicron N- 775, Epicron N-865, Epicron HP-4032D, Epicron HP-7200L, Epicron HP-7200, Epicron HP-7200H, Epicron HP-7200HH, Epicron HP-7200HHH, Epicron HP-4700, Epicron HP-4710, Epicron HP-4770, Epicron HP-5000, Epicron Cron HP-6000 and N500P-2 (all trade names of 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-502H, Examples thereof include EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, and BREN-10S (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.), and YX-4000, YX-4000H, YL4121H, and YX-8800 (all of which are trade names manufactured by Mitsubishi Chemical Corporation).

[0042] The epoxy resin (A) in embodiment A preferably contains an epoxy resin that is solid at room temperature. The content of the epoxy resin that is solid at room temperature is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 95% by mass or more, based on the total amount of epoxy resin. The content of the epoxy resin that is solid at room temperature is preferably 100% by mass or less, more preferably 99% by mass or less, based on the total amount of epoxy resin. When the epoxy resin satisfies the above-mentioned configuration, it becomes easier to control the value of (X) - (Y) within a desired range, which enables the fixing strength during low-temperature curing to be increased and also suppresses blocking of the compound.

[0043] The epoxy resin content is preferably 1% by volume or more and 35% by volume or less, more preferably 3% by volume or more and 30% by volume or less, and even more preferably 5% by volume or more and 25% by volume or less, based on the total volume of the compound. By keeping the epoxy resin content within this range, the bonded magnet can achieve both good magnetic properties and good mechanical strength.

[0044] The epoxy resin content is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 2% by mass or more and 10% by mass or less, relative to the total mass of the compound. By keeping the epoxy resin content within this range, the bonded magnet can achieve both good magnetic properties and good mechanical strength.

[0045] <Curing Agent (B)> The compound of embodiment A preferably contains a curing agent (B) different from the curing agent (D). Examples of the curing agent include, but are not limited to, aliphatic polyamines, polyaminoamides, polymercaptans, aromatic polyamines, acid anhydrides, phenolic resins, and dicyandiamide (DICY).

[0046] From the viewpoint of increasing the heat resistance of the bonded magnet, it is preferable to use aromatic polyamines, acid anhydrides, phenolic resins, and dicyandiamide (DICY) as the curing agent, and among these, it is more preferable to use phenolic resins.

[0047] Examples of phenolic resins include aralkyl-type phenolic resins, dicyclopentadiene-type phenolic resins, salicylaldehyde-type phenolic resins, novolac-type phenolic resins, copolymerized phenolic resins of benzaldehyde-type phenols and aralkyl-type phenols, paraxylylene- and / or metaxylylene-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, triphenylmethane-type phenolic resins, etc. The phenolic resin may be a copolymer composed of two or more of the above.

[0048] The phenolic resin is preferably a novolac phenolic resin from the viewpoint of improving the heat resistance of the bonded magnet. Examples of novolac phenolic resins include resins obtained by condensing or co-condensing phenols and / or naphthols with aldehydes under an acidic catalyst. Examples of phenols that constitute novolac phenolic resins include phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. Examples of naphthols that constitute novolac phenolic resins include α-naphthol, β-naphthol, and dihydroxynaphthalene. Examples of aldehydes that constitute novolac phenolic resins include formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0049] The curing agent may be, for example, a compound having two phenolic hydroxyl groups in one molecule, such as resorcinol, catechol, bisphenol A, bisphenol F, or substituted or unsubstituted biphenol.

[0050] The curing agent may be used alone or in combination of two or more of the above. The ratio of the active group (phenolic OH group) in the curing agent that reacts with the epoxy group 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, per equivalent of the epoxy group in the epoxy resin. By ensuring that the ratio of the active group in the curing agent satisfies the above range, the mechanical properties and heat resistance of the bonded magnet can be improved.

[0051] The curing agent (B) in embodiment A preferably contains a curing agent that is solid at room temperature. The content of the curing agent that is solid at room temperature is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 95% by mass or more, based on the total amount of the curing agent (B). When the curing agent (B) satisfies the above-mentioned configuration, it becomes easier to control the value of (X) - (Y) within a desired range, which increases the fixing strength during low-temperature curing and also suppresses blocking of the compound.

[0052] The content of curing agent (B) is preferably 1% by volume or more and 35% by volume or less, more preferably 3% by volume or more and 30% by volume or less, and even more preferably 5% by volume or more and 25% by volume or less, relative to the total volume of the compound. By ensuring that the content of curing agent (B) satisfies the above range, the mechanical strength of the bonded magnet can be increased. The content of curing agent (B) is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 2% by mass or more and 10% by mass or less, relative to the total mass of the compound. By ensuring that the content of curing agent (B) satisfies the above range, the mechanical strength of the bonded magnet can be improved.

[0053] <Magnetic Particles (C)> The compound of embodiment A contains magnetic particles. The magnetic particles may be used alone or in combination of two or more types. When two or more types of magnetic particles are mixed, two or more types of magnetic particles having different alloy compositions, particle sizes (particle size distribution), shapes, properties (isotropy, anisotropy), surface treatments, etc. may be mixed and used.

[0054] The alloy composition of the magnetic particles is not limited as long as it does not deteriorate the curing properties of the resin composition. Examples of the magnetic particles that can be used include 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, and ferrite magnet particles.

[0055] The magnetic particles of embodiment A are preferably rare earth magnetic particles. Rare earth magnetic particles have superior coercivity and magnetic flux density compared to other magnetic particles, and can increase the magnetic force of a bonded magnet, for example.

[0056] The shape of the magnetic particles is not particularly limited, but spherical, flat, prismatic, needle-shaped magnetic particles, etc. can be used alone or in combination. The shape of the magnetic particles can be evaluated by the circularity coefficient measured by image processing of images observed under a microscope. The circularity coefficient is a value defined by the following formula, and the higher the value, the more rounded the particles are and the closer they are to a sphere. From the viewpoint of facilitating rotation of the magnetic particles during magnetic field molding and improving orientation, it is preferable to include at least one type of magnetic particle with a circularity coefficient of 0.70 or more.

[0057] The magnetic particles may have a particle size (particle size distribution) of either coarse magnetic particles (hereinafter simply referred to as "coarse particles") or fine magnetic particles (hereinafter simply referred to as "fine particles"), and these may be used alone or in combination.

[0058] The average particle size (D50) of the coarse particles is preferably 30 μm or more and 300 μm or less, and more preferably 40 μm or more and 250 μm or less. Because the coarse particles have high magnetic properties, the magnetic properties of the bonded magnet can be adjusted depending on the amount of coarse particles added. The average particle size (D50) of the fine particles is preferably 0.5 μm or more and 30 μm or less, and preferably 1 μm or more and 20 μm or less. The fine particles can increase the filling amount of magnetic particles, thereby improving magnetic properties. The average particle size and particle size distribution of the magnetic particles are measured using a laser diffraction particle size distribution analyzer (HELOS, manufactured by Nippon Laser Co., Ltd.).

[0059] The properties of the magnetic particles are not particularly limited, but anisotropic magnetic particles and isotropic magnetic particles can be used alone or in combination. By preparing a compound using anisotropic magnetic particles and then orienting the magnetic particles in the bonded magnet compact by magnetic field molding, the magnetic properties can be improved.

[0060] The magnetic particles are preferably subjected to anti-rust treatment. Examples of anti-rust treatment include phosphate 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 gradual oxidation treatment to form an oxide film. The anti-rust treatment may be performed using a single type of treatment or a combination of multiple types of treatments.

[0061] The content of the magnetic particles is preferably 40% by volume or more and 95% by volume or less, more preferably 45% by volume or more and 90% by volume or less, and even more preferably 50% by volume or more and 85% by volume or less, based on the total volume of the compound. When the content of the magnetic particles satisfies the above range, it becomes easier to control the value of (X) - (Y) in formula (2).

[0062] <Curing Agent (D)> The compound of embodiment A contains a curing agent (D). The curing agent (D) is not limited to the following, but is preferably a latent curing agent, for example, from the viewpoint of achieving both storage stability and fixing strength during low-temperature curing.

[0063] Examples of latent curing agents include, but are not limited to, imidazole compounds, amine-based adducts such as amine-epoxy adducts and amine-urea adducts, capsule-type curing agents formed by coating these compounds, and curing agents adsorbed on porous materials. From the viewpoint of a balance between storage stability and reactivity, the curing agent (D) preferably contains an amine-epoxy adduct, and more preferably contains an adduct of an imidazole compound and a bisphenol A-type epoxy resin. The curing agent (D) may be at least one selected from the group consisting of imidazole compounds and amine-based adduct compounds. In the compound of embodiment A, from the viewpoint of achieving both storage stability and fixing strength during low-temperature curing, the curing agent (D) preferably contains a capsule-type curing agent.

[0064] The capsule-type hardener exhibits high stability due to the shielding effect of the capsule membrane, preventing the hardener components from diffusing into the epoxy resin and hardener during compound storage. Meanwhile, during the pressure molding process of the compound, the capsule membrane is destroyed by the application of pressure to the compound, allowing the hardener components to diffuse into the epoxy resin. This increases the fixing strength during low-temperature hardening. The effects of the present invention can be realized by the multiple magnetic powder particles compressing the microcapsules, destroying the capsule membrane.

[0065] The capsule-type curing agent preferably has a structure in which the surface of a core containing a curing agent is covered with a shell containing a synthetic resin and / or an inorganic oxide. Among these, from the viewpoints of the stability of the film constituting the shell and the ease of destruction when heated and pressurized, it is preferable that the shell constituting the capsule-type curing agent contains a synthetic resin. The core is not limited to the following, but is preferably solid at room temperature from the viewpoint of storage stability. For example, a solid imidazole compound, or an amine-based adduct compound such as an amine-epoxy adduct or an amine-urea adduct can be used. Among these, from the viewpoint of the balance between storage stability and reactivity, it is preferable that the core contains an amine-epoxy adduct, and more preferably contains an adduct of an imidazole compound and a bisphenol A-type epoxy resin.

[0066] Examples of synthetic resins contained in the shell include, but are not limited to, epoxy resins, phenol resins, polyester resins, polyethylene resins, nylon resins, polystyrene resins, urethane resins, etc. Among these, epoxy resins, phenol resins, and urethane resins are preferred as the synthetic resin from the viewpoint of the balance between the stability of the film constituting the shell and its destructibility upon heating and pressure application.

[0067] Epoxy resins used for the shell include, but are not limited to, epoxy resins having two or more epoxy groups, resins produced by the reaction of an epoxy resin having two or more epoxy groups with a compound having two or more active hydrogens, and reaction products of a compound having two or more epoxy groups with a compound having one active hydrogen and a carbon-carbon double bond. Among these, from the viewpoint of stability, reaction products of a compound having two or more epoxy groups with a compound having two or more active hydrogens are preferred, and reaction products of an amine curing agent and an epoxy resin having two or more epoxy groups are particularly preferred.

[0068] Examples of phenolic resins include, but are not limited to, phenol-formaldehyde polycondensates, cresol-formaldehyde polycondensates, resorcinol-formaldehyde polycondensates, bisphenol A-formaldehyde polycondensates, and polyethylene polyamine-modified phenol-formaldehyde polycondensates.

[0069] Examples of polyester resins include, but are not limited to, ethylene glycol-terephthalic acid-polypropylene glycol polycondensates, ethylene glycol-butylene glycol-terephthalic acid polycondensates, and terephthalic acid-ethylene glycol-polyethylene glycol polycondensates.

[0070] Examples of polyethylene resins include, but are not limited to, ethylene-propylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, and ethylene-vinyl acetate-acrylic acid copolymers.

[0071] Examples of nylon resins include, but are not limited to, adipic acid-hexamethylenediamine polycondensate, sebacic acid-hexamethylenediamine polycondensate, and p-phenylenediamine-terephthalic acid polycondensate.

[0072] Examples of polystyrene resins include, but are not limited to, styrene-butadiene copolymers, styrene-butadiene-acrylonitrile copolymers, acrylonitrile-styrene-divinylbenzene copolymers, and styrene-propenyl alcohol copolymers.

[0073] Examples of urethane resins include, but are not limited to, isocyanate monomers such as butyl isocyanate, cyclohexyl isocyanate, octadecyl isocyanate, phenyl isocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate, or condensates thereof, or polycondensates of polymers thereof with monoalcohols or polyhydric alcohols. Among these, urethane resins, which are addition polymers obtained by adding monoisocyanates or polyhydric isocyanates to monoalcohols or polyhydric alcohols, are preferred.

[0074] Examples of inorganic oxides include, but are not limited to, boron oxide, boron compounds such as boric acid esters, silicon dioxide, calcium oxide, etc. Among these, boron oxide is preferred from the viewpoints of the stability of the film constituting the shell and the ease of destruction when heated.

[0075] From the viewpoint of the balance between the storage stability and curability of the compound of embodiment A, the shell preferably contains at least one reaction product selected from the group consisting of an isocyanate compound, an active hydrogen compound, a curing agent for an epoxy resin, an epoxy resin, and an amine compound.

[0076] Examples of isocyanate compounds include, but are not limited to, aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aliphatic triisocyanates, polyisocyanates, etc. Examples of aliphatic diisocyanates include, but are not limited to, ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, etc. Examples of alicyclic diisocyanates include, but are not limited to, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,4-isocyanatocyclohexane, 1,3-bis(isocyanatomethyl)-cyclohexane, 1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane, etc. Examples of aromatic diisocyanates include, but are not limited to, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, and 1,5-naphthalene diisocyanate. Examples of aliphatic triisocyanates include, but are not limited to, 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, and 1,3,6-triisocyanatomethylhexane. Examples of polyisocyanates include, but are not limited to, polymethylene polyphenyl polyisocyanate and polyisocyanates derived from diisocyanate compounds. Examples of polyisocyanates derived from diisocyanate compounds include isocyanurate-type polyisocyanates, biuret-type polyisocyanates, urethane-type polyisocyanates, allophanate-type polyisocyanates, and carbodiimide-type polyisocyanates.

[0077] Examples of active hydrogen compounds include, but are not limited to, water, compounds having at least one primary amino group and / or secondary amino group, compounds having at least one hydroxyl group, etc. These active hydrogen compounds may be used alone or in combination of two or more.

[0078] Examples of compounds having at least one primary amino group and / or secondary amino group include, but are not limited to, aliphatic amines, alicyclic amines, aromatic amines, etc. Examples of aliphatic amines include, but are not limited to, alkylamines such as methylamine, ethylamine, propylamine, butylamine, and dibutylamine; alkylenediamines such as ethylenediamine, propylenediamine, butylenediamine, and hexamethylenediamine; polyalkylenepolyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; and polyoxyalkylenepolyamines such as polyoxypropylenediamine and polyoxyethylenediamine. Examples of alicyclic amines include, but are not limited to, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, and isophoronediamine. Examples of aromatic amines include, but are not limited to, aniline, toluidine, benzylamine, naphthylamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

[0079] Examples of compounds having at least one hydroxyl group include alcohol compounds, phenol compounds, etc. Examples of alcohol compounds include, but are not limited to, methyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, dodecyl alcohol, stearyl alcohol, eicosyl alcohol, allyl alcohol, crotyl alcohol, propargyl alcohol, cyclopentanol, cyclohexanol, benzyl alcohol, cinnamyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diglyceryl ether, methyl ... Examples of the alcohol compound include monoalcohols such as ethylene glycol monobutyl; polyhydric alcohols such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butanediol, 1,4-butanediol, hydrogenated bisphenol A, neopentyl glycol, glycerin, trimethylolpropane, and pentaerythritol; and polyhydric alcohols such as compounds having two or more secondary hydroxyl groups per molecule, obtained by reacting a compound having at least one epoxy group with a compound having at least one hydroxyl group, carboxyl group, primary amino group, secondary amino group, or thiol group. These alcohol compounds may be primary, secondary, or tertiary alcohols. Examples of phenolic compounds include, but are not limited to, monophenols such as carbolic acid, cresol, xylenol, carvacrol, motil, and naphthol, and polyhydric phenols such as catechol, resorcinol, hydroquinone, bisphenol A, bisphenol F, pyrogallol, phloroglucin, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol. From the viewpoints of latency and solvent resistance, these compounds having at least one hydroxyl group are preferably polyhydric alcohols and polyhydric phenols, and more preferably polyhydric alcohols.

[0080] The reaction conditions for preparing the reaction product of at least one selected from the group consisting of an isocyanate compound, an active hydrogen compound, an epoxy resin curing agent, an epoxy resin, and an amine compound contained in the shell constituting the capsule-type curing agent as described above are not particularly limited. For example, the reaction is usually carried out at a temperature in the range of −10° C. to 150° C. for a reaction time of 10 minutes to 100 hours.

[0081] When an isocyanate compound and an active hydrogen compound are used to prepare the reaction product contained in the shell, the compounding ratio, expressed as an equivalent ratio of (isocyanate group in the isocyanate compound):(active hydrogen in the active hydrogen compound), is preferably in the range of 1:0.1 to 1:1000.

[0082] Examples of the imidazole compound include, but are not limited to, imidazoles such as imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-aminoethyl-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, and 1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole; and compounds obtained by reacting these imidazoles with at least one selected from the group consisting of carboxylic acid compounds, sulfonic acid compounds, urea compounds, isocyanate compounds, and epoxy resins.

[0083] Examples of the amine-based adduct compound include compounds obtained by reacting at least one selected from the group consisting of carboxylic acid compounds, sulfonic acid compounds, urea compounds, isocyanate compounds, and epoxy resins with an amine-based curing agent. The above-mentioned curing agents may be used alone or in combination of two or more.

[0084] In the compound of embodiment A, the content of curing agent (D) 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). When the content of curing agent (D) satisfies the above range, it is easy to control the fixing strength during low-temperature curing within an appropriate range. Furthermore, the content of curing agent (D) is preferably 15.0 parts by mass or less, more preferably 12.0 parts by mass or less, and even more preferably 10.0 parts by mass or less, relative to 100 parts by mass of epoxy resin (A). When the content of curing agent (D) satisfies the above range, it is easy to control the storage stability of the compound of embodiment A within an appropriate range.

[0085] <Lubricant> The compound of embodiment A may contain a lubricant. By including a lubricant in the compound, the flowability and moldability of the compound are improved, and the releasability of the compound is improved. As a result, the accuracy of the shape and dimensions of the bonded magnet is improved, and structural defects of the bonded magnet are more likely to be suppressed.

[0086] The lubricant 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. The wax may be, for example, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, heneicosylic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, calcium laurate, calcium myristate, calcium pentadecylate, calcium palmitate, calcium margaric acid, calcium stearate, calcium arachidic acid, calcium heneicosylate, calcium behenate, calcium lignocerate, calcium cerotic acid, calcium montanic acid, calcium melissic acid, barium laurate, barium myristate, pentadecyl The compound may be at least one selected from the group consisting of barium ester, barium palmitate, barium margarate, barium stearate, barium arachidate, barium heneicosylate, barium behenate, barium lignocerate, barium cerotate, barium montanate, barium melissate, laurate, myristate, pentadecylate, palmitate, margarate, stearate, arachidate, heneicosylate, behenate, lignocerate, cerotate, montanate, and melissate. The compound may contain waxes other than those mentioned above.For example, the wax may be at least one selected from the group consisting of magnesium salts of the saturated fatty acids, aluminum salts of the saturated fatty acids, 12-oxystearic acid, calcium ricinoleate, stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, lauric acid amide, hydroxystearic acid amide, methylene bisstearic acid amide, ethylene bisstearic acid amide, ethylene bislauric acid amide, distearyl adipamide, ethylene bisoleic acid amide, dioleyl adipamide, N-stearyl stearic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid amide, methylol behenic acid amide, ethylene glycol, stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, silicone oil, silicone grease, fluorine-based oil, fluorine-based grease, fluorine-containing resin powder, paraffin wax, polyethylene wax, amide wax, polypropylene wax, ester wax, carnauba wax, and microwax. The compound may contain one of the lubricants listed above. The compound may contain multiple of the lubricants listed above.

[0087] Instead of or in addition to blending the lubricant into the compound, a dispersion of the internal lubricant may be applied to the inner wall surface of the die (the wall surface that comes into contact with the punch).

[0088] <Coupling Agent> The compound of embodiment A may contain a coupling agent. By including a coupling agent, it is possible to further increase the adhesion between the resin composition and the surface of the magnetic particles, and further increase the strength of the bonded magnet. Examples of coupling agents include coupling agents for silane-based compounds such as epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, and vinylsilane; coupling agents for titanium-based compounds; coupling agents for aluminum chelates; and coupling agents for aluminum / zirconium-based compounds.

[0089] <Flow Aid> The compound of the present invention may contain an inorganic filler as a flow aid. The inorganic filler may be composed of one type of particle. The inorganic filler may also be a combination of two or more types of particles. 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 can increase the space filling rate of the bonded magnet.

[0090] Examples of inorganic fillers include inorganic fine particles such as silica, alumina, calcium carbonate, kaolin clay, titanium oxide, barium sulfate, zinc oxide, aluminum hydroxide, magnesium hydroxide, talc, and mica.

[0091] <Flame Retardant> The compound of embodiment A may contain a flame retardant. By containing a flame retardant, the fire resistance of the compound can be improved. From the viewpoints of environmental safety, recyclability, moldability, and low cost, the flame retardant is preferably at least one selected from the group consisting of bromine-based flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics.

[0092] <Organic Solvent (E)> In the compound manufacturing process, a varnish is prepared by dissolving the resin composition in an organic solvent, and the surface of each magnetic particle constituting the magnetic particles is coated with the varnish to obtain a uniform compound. The organic solvent is not limited as long as it is a solvent that can dissolve the resin composition. The organic solvent may be, for example, at least one solvent selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, and xylene. In consideration of workability, the organic solvent is preferably liquid at room temperature, and the boiling point of the organic solvent is preferably 60°C or higher and 150°C or lower. Examples of such solvents include acetone and methyl ethyl ketone.

[0093] <Embodiment B> The compound of embodiment B (hereinafter also simply referred to as "compound") is a compound containing an epoxy resin (A), magnetic particles (C), and a curing agent (D), where the curing agent (D) is a capsule-type curing agent. The compound of embodiment B preferably contains a curing agent (B) that is different from the curing material (D). The core component of the curing agent (D) is solid and preferably contains an amine-epoxy adduct.

[0094] Specific examples, preferred examples, preferred contents, preferred aspects, etc. of the epoxy resin (A), curing agent (B), magnetic particles (C), and curing agent (D) are the same as those of the epoxy resin (A), curing agent (B), magnetic particles (C), and curing agent (D) in the above-described embodiment A. Specific examples, preferred examples, preferred contents, preferred aspects, etc. of the curing agent (D) are the same as those of the curing agent (D) in the above-described embodiment A. <Varnish> The varnish of this embodiment contains an epoxy resin (A), a curing agent (B), a curing agent (D), and an organic solvent (E), wherein the curing agent (D) contains a capsule-type curing agent, and the core component of the curing agent (D) is solid and contains an amine-epoxy adduct. The varnish of this embodiment may be used for bonded magnets and can be used in the process of producing a bonded magnet compound described below.

[0095] <Method for Producing Compound> The method for producing the compound of the present embodiment is not particularly limited, and examples thereof include a method of mixing the resin composition at a temperature equal to or higher than the melting point (hereinafter simply referred to as "melt mixing") and a method of dissolving the resin composition in a solvent and mixing the same (hereinafter simply referred to as "dissolution mixing").

[0096] Melt mixing may be performed by the following method. A mixed powder of compound raw materials (epoxy resin, curing agent, magnetic particles, and other additives) is obtained by thoroughly mixing the compound raw materials in a mixer. The obtained mixed powder of compound raw materials is heated and mixed at a temperature above the softening temperature of the resin composition, and solids are crushed as needed to obtain a compound. The heating and mixing temperature depends on the type and amount of resin composition, but is preferably 40°C or higher and 140°C or lower, and more preferably 60°C or higher and 120°C or lower. Heating and mixing within the above temperature range can suppress the curing reaction of the resin composition while improving the dispersion of materials in the compound. The mixing device is not particularly limited, but a heated kneader, for example, can be used. In this case, the dispersion of materials can be controlled by changing the amount of compound raw materials added.

[0097] The dissolution and mixing may be carried out by the following method. The raw materials of the resin composition, such as epoxy resin and curing agent, are dissolved in an organic solvent to obtain a solution (varnish) of the resin composition. The magnetic particles are added to the resin composition solution to disperse the magnetic particles in the resin composition solution, and then the organic solvent is removed from the solution containing the magnetic particles and the resin composition by vacuum distillation and drying. As a result, the surfaces of the magnetic particles are coated with the resin composition, and a compound consisting of the magnetic particles and the resin composition is obtained.

[0098] In the step of removing the organic solvent from the solution containing the magnetic particles and the resin composition, it is preferable to use an evaporator to distill off the organic solvent under reduced pressure at room temperature while stirring the solution. The solid obtained by distillation under reduced pressure is further dried using a vacuum dryer or the like, and then the solid is appropriately pulverized to obtain a compound. Instead of distillation under reduced pressure, distillation under normal pressure may be performed while stirring the solution using a kneader or the like. The solid obtained by distillation may be dried, for example, by heating the solid at 80°C or less, preferably 60°C or less, more preferably 40°C or less.

[0099] <Method for manufacturing bonded magnet> The bonded magnet of this embodiment is a bonded magnet made by molding and hardening a compound. A molded body is obtained by compression molding the compound filled into a mold. The higher the molding pressure, the higher the density of the bonded magnet, but the more likely it is that the magnetic particles will crack. The molding pressure can be set as desired to suit the characteristics of the compound and the bonded magnet.

[0100] By heat treating the molded body, the resin composition in the molded body is cured, and the magnetic particles in the molded body are bound to each other by the cured resin composition, resulting in a bonded magnet. The heat treatment temperature for the molded body is preferably set to a temperature at which the resin composition is sufficiently cured. Furthermore, from the viewpoint of suppressing oxidation of the magnetic particle surface, low-temperature curing and short-time curing are preferred. The curing temperature is, for example, preferably 200°C or less, more preferably 180°C or less, and even more preferably 150°C or less. The curing time is, for example, preferably 120 minutes or less, more preferably 60 minutes or less, and even more preferably 30 minutes or less.

[0101] When orienting the magnetic particles, a magnetic field may be applied before and during compaction, and during heat treatment of the compact. The bonded magnet of this embodiment can be preferably used for motors. The motor of this embodiment includes the bonded magnet of this embodiment.

[0102] The present embodiment will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to these examples and comparative examples. In the following, "parts" and "%" are by mass unless otherwise specified.

[0103] [Bonded Magnet Compound] (Epoxy Resins (A-1) to (A-7)) Table 1 shows the epoxy resins (A-1) to (A-7) used in each of the Examples and Comparative Examples.

[0104]

[0105] (Curing Agents (B-1) to (B-3)) Table 2 shows the epoxy resins (B-1) to (B-3) used in each of the Examples and Comparative Examples.

[0106]

[0107] (Magnetic Particles (C-1) to (C-2)) Table 3 shows the magnetic particles (C-1) to (C-2) used in each of the examples and comparative examples.

[0108]

[0109] (Hardening Agents (D-1) to (D-5)) Table 4 shows the magnetic particles (D-1) to (D-5) used in each of the Examples and Comparative Examples.

[0110]

[0111] <Production Example of Curing Agent (D-1)> One equivalent of epoxy resin (A-3) and one equivalent of 2-methylimidazole (converted to active hydrogen) were reacted at 80°C in a 1:1 mixed solvent of n-butanol and toluene. The excess amine was then distilled off together with the solvent under reduced pressure, yielding a solid block curing agent 1 at 25°C. The block curing agent 1 was roughly crushed to particles of approximately 0.1 to 2 mm using a crusher "Rotoplex" (manufactured by Hosokawa Micron Corporation), and the resulting crushed material was pulverized using an air jet mill (manufactured by Nisshin Engineering Inc., CJ25 model). The crushed material was then classified using an air classifier "Turbo Classifier" (manufactured by Nisshin Engineering Inc.) to yield a solid curing agent (D-1) at 25°C.

[0112] <Production Example of Curing Agent (D-2)> 100 parts by mass of epoxy resin (A-3), 100 parts by mass of epoxy resin (A-4), 100 parts by mass of curing agent (D-1), and 10 parts by mass of an encapsulating agent (MR-200, manufactured by Nippon Polyurethane Co., Ltd.) were added, dispersed, and mixed, and then reacted at 25°C to 55°C for 5 hours and at 60°C for 48 hours to obtain a capsule-type curing agent (D-2) dispersed in the epoxy resin.

[0113] [Preparation of Bonded Magnet Compound] (Example 1) 4.0 g of epoxy resin (A-1), 3.17 g of curing agent (B-1), 0.3 g of curing agent (D-2), and 33.0 g of methyl ethyl ketone were mixed in a 300 mL eggplant flask and stirred for an additional 30 minutes to prepare a solution of a resin composition (resin solution). The curing agent (D-2) used contained 0.1 g of capsule-type curing agent, 0.1 g of epoxy resin (A-3), and 0.1 g of epoxy resin (A-4).

[0114] 67.5 g of magnetic particles (C-1) were added to the eggplant flask containing the resin solution and stirred at 25°C for 30 minutes. The pressure inside the evaporator was then reduced to 0.1 MPa or less, completely distilling off the solvent from the flask. During the solvent distillation process, the following operations were repeated several times in this order to thoroughly remove the solvent: reducing the pressure inside the flask, restoring the pressure inside the flask to normal pressure, and loosening the aggregated contents inside the flask. After distilling off the solvent, the mixture of resin composition and magnetic particles was recovered from the flask and spread on a flat plate. The mixture on the plate was dried at room temperature for 8 hours in a vacuum dryer. After drying, the aggregated mixture was coarsely pulverized to obtain a bonded magnet compound (CPD-1). The resulting bonded magnet compound was used to perform the following evaluations.

[0115] (Examples 2 to 17, Comparative Examples 2 to 10) Bonded magnet compounds (CPD-2) to (CPD-17) and (CPD-19) to (CPD-27) were obtained in the same manner as in Example 1, except that the formulation was changed to the formulation shown in Table 5. Evaluations were carried out in the same manner as in Example 1.

[0116] (Comparative Example 1) 4.10 g of epoxy resin (A-3), 3.10 g of curing agent (B-2), and 0.1 g of curing agent (D-1) were placed in a plastic stirring container, and this was stirred and mixed using a centrifugal mixer ("ARE-310" manufactured by Thinky Corporation) to obtain a resin composition. 65.5 g of magnetic particles (C-1) were added to the above resin composition, and the mixture was stirred and mixed using the centrifugal mixer to obtain a bonded magnet compound (CPD-17). Evaluation was carried out in the same manner as in Example 1.

[0117] [Evaluation] (Exothermic peak temperatures (X) and (Y) in differential scanning calorimetry) The bonded magnet compounds obtained in the examples and comparative examples were measured from 25 to 250°C at 2°C / min using a DSC measuring device Q2000 manufactured by TA Instruments, to obtain calorimetry curves. For the obtained calorimetry curves, the exothermic peak temperature at which the heat release was greatest was taken as (X).

[0118] Similarly, the bonded magnet compounds obtained in the examples and comparative examples were pressurized at 200 MPa for 5 minutes to obtain calorie curves for the samples, and the exothermic peak temperature at which the heat generation amount reached a maximum was designated as (Y). The bonded magnet compounds were pressed using a powder molding die (manufactured by LabNect Co., Ltd.) with a diameter of φ10.0 mm, and the resulting pellets were broken up to obtain measurement samples. The pellets had a thickness of 1.0 mm.

[0119] (Fixing strength to steel plate) A powder molding die (manufactured by LabNect Co., Ltd.) with a diameter of φ10.0 mm was filled with the bond magnet compound of each example and comparative example, and a pressure of 200 MPa was applied for 1 minute to form a pellet with a thickness of 1.0 mm. The resulting pellet was sandwiched between two standard test plates (SPCC-SB, 1.6 mm x 25 mm x 100 mm, manufactured by Nippon Test Panel Co., Ltd.) and hot-pressed using a hydraulic molding machine TM-10 (manufactured by Toho Machinery Co., Ltd.) to prepare a test specimen. The heating conditions for the hydraulic molding machine were 150 °C for 30 minutes, and the compression conditions were 200 MPa. The fixing position of the pellet relative to the test specimen is shown in Figure 1. The obtained test pieces were measured using an autograph tester (AGX-5kNX, manufactured by Shimadzu Corporation) at a load cell of 5 kN and a speed of 5 mm / min to measure the maximum load at which the fixing surface of the test piece broke and the test piece separated. The maximum load at which the test piece separated was divided by the adhesive area to determine the fixing strength. Ranks A, B, and C were rated as passing. <Evaluation criteria> A: Fixing strength of 1200 N / mm ２ B: Fixing strength was 1000 N / mm or more. ２ More than 1200N / mm ２ C: Fixing strength was less than 800 N / mm ２ More than 1000N / mm ２ D: Fixing strength was less than 600 N / mm ２ More than 800N / mm ２ E: Fixing strength was less than 600 N / mm ２ It was less than.

[0120] (Storage Stability) The bonded magnet compound (CPD-1) was left in a 40°C environment for 7 days, and after leaving, the bonded magnet compound (CPD-1) was used to measure the fixing strength to a steel plate. Based on the fixing strength to the steel plate before and after leaving, the fixing strength reduction rate was calculated from the following formula (3) and used as an index of storage stability. Fixing strength reduction rate = Fixing strength to steel plate after leaving at 40°C for 7 days / Fixing strength to steel plate × 100 (3) Ranks A, B, and C were rated as passing. <Evaluation Criteria> A: The fixing strength reduction rate to the steel plate was less than 10.0%. B: The fixing strength reduction rate to the steel plate was 10.0% or more and less than 15.0%. C: The fixing strength reduction rate to the steel plate was 15.0% or more and less than 20.0%. D: The fixing strength reduction rate to the steel plate was 20.0% or more and less than 25.0%. E: The fixing strength reduction rate to the steel plate was 25.0% or more.

[0121] (Blocking properties) Bonded magnet compound (CPD-1) was left in a 40°C environment for 7 days, and the change in particle size of the compound before and after leaving it was evaluated. Ranks A and B were considered to be passing. <Evaluation criteria> A: No change in particle size of the compound was observed. B: Coalescence of the compound was observed, but it broke apart when touched with a finger. C: Coalescence of the compound was observed, but it did not break apart when touched with a finger. D: The compound had coalesced into blocks.

[0122] The compositions of the bonded magnet compounds (CPD-1 to CPD-17) of Examples 1 to 17 and the bonded magnet compounds (CPD-18 to CPD-27) of Comparative Examples 1 to 10 are shown in Table 5 below, and the evaluation results are shown in Table 6 below.

[0123]

[0124]

[0125] As shown in Tables 5 and 6, when a compound containing an epoxy resin (A), magnetic particles (C), and a curing agent (D) is used in differential scanning calorimetry, the exothermic peak temperature of the calorific curve at a heating rate of 2°C / min is (X), and the exothermic peak temperature of the calorific curve at a heating rate of 2°C / min after pressurizing the compound at 200 MPa for 5 minutes is (Y), the examples in which (X) and (Y) satisfy formulas (1) and (2) respectively exhibited excellent storage stability and high fixing strength to metal members even when the thermosetting resin was cured under low-temperature conditions. On the other hand, the comparative examples in which (X) - (Y) was less than 3 exhibited poor storage stability and also poor fixing strength to metal members when the thermosetting resin was cured under low-temperature conditions.

[0126] The present invention may include the following embodiments. <1> A bonded magnet compound comprising an epoxy resin (A), a curing agent (B), magnetic particles (C), and a curing accelerator (D), wherein, in a differential scanning calorimetry measurement, when the exothermic peak temperature of the calorific curve of the bonded magnet compound at a heating rate of 2°C / min is (X), and when the exothermic peak temperature of the calorific curve of the bonded magnet compound at a heating rate of 2°C / min after pressurizing the bonded magnet compound at 200 MPa for 5 minutes is (Y), (X) and (Y) satisfy the following formulas (1) and (2): 100≦(X)≦200 (1) (X) - (Y)≧3 (2) <2> The bonded magnet compound according to <1>, wherein the epoxy resin (A) includes an epoxy resin that is solid at room temperature, and the content of the epoxy resin is 50 mass% or more relative to the total amount of epoxy resins. <3> The bonded magnet compound according to <1> or <2>, wherein the curing agent (B) contains a curing agent that is solid at room temperature, and the content of the curing agent is 50% by mass or more relative to the total amount of curing agent. <4> The bonded magnet compound according to any one of <1> to <3>, wherein the content of the magnetic particles (C) is 40% by volume or more and 95% by volume or less relative to the total volume of the bonded magnet compound. <5> The bonded magnet compound according to any one of <1> to <4>, wherein the magnetic particles (C) are rare earth magnetic particles. <6> The bonded magnet compound according to any one of <1> to <5>, wherein the curing accelerator (D) contains a microcapsule-type latent accelerator. <7> The bonded magnet compound according to any one of <1> to <6>, wherein the content of the curing accelerator (D) is 0.1 parts by mass or more and 15.0 parts by mass or less relative to 100 parts by mass of the epoxy resin (A). <8> A bonded magnet compound comprising an epoxy resin (A), a curing agent (B), magnetic particles (C), and a curing accelerator (D), wherein the curing accelerator (D) is a microcapsule-type latent accelerator.

[0127] The disclosure of Japanese Patent Application No. 2020-106880, filed on July 13, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0128] The compound of the present invention has industrial applicability as a material for various bonded magnets.

[0129] 1 Pellets 2 Steel plate

Claims

1. A compound comprising an epoxy resin (A), magnetic particles (C), and a curing agent (D), wherein, in a differential scanning calorimetry measurement, when the exothermic peak temperature of a heat curve of the compound at a heating rate of 2°C / min is (X), and when the exothermic peak temperature of the heat curve of the compound at a heating rate of 2°C / min after pressurizing the compound at 200 MPa for 5 minutes is (Y), (X) and (Y) satisfy the following formulas (1) and (2): 100≦(X)≦200... (1) (X)-(Y)≧3... (2) 2. The compound of claim 1, wherein the curing agent (D) comprises an encapsulated curing agent.

3. The compound according to claim 1, wherein the content of the curing agent (D) is 0.1 parts by mass or more and 15.0 parts by mass or less per 100 parts by mass of the epoxy resin (A).

4. The compound according to claim 2, wherein the core component of the hardener (D) is a solid.

5. The compound of claim 1, wherein the curing agent (D) comprises an amine-epoxy adduct.

6. The compound of claim 5, wherein said amine-epoxy adducts comprise an adduct of an imidazole compound and a bisphenol A type epoxy resin.

7. The compound of claim 1 further comprising a curing agent (B).

8. The compound according to claim 7, wherein the curing agent (B) contains a curing agent that is solid at room temperature, and the content of the curing agent that is solid at room temperature is 50 mass% or more based on the total amount of the curing agent (B).

9. The compound according to claim 1, wherein the epoxy resin (A) comprises a structure represented by the following formula (A1): (In formula (A1), R １ ~R ３ are each independently a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a heteroatom, or a substituent containing a halogen atom; R １ ~R ３ At least one of the groups contains a reactive group with the curing agent (D), and R １ ~R ３ may be the same or different.) 10. The compound according to claim 1, wherein the epoxy resin (A) comprises a structure represented by the following formula (A2): (In formula (A2), R １ , R ２ is an alkyl group having 1 to 12 carbon atoms, and m and n are each independently an integer of 1 or more. １ and G ２ is one selected from the group consisting of a hydrogen atom, an alkyl group, an aromatic group, a substituent containing a heteroatom, and a substituent containing a halogen atom. １ and G ２ may be the same or different.) 11. The compound according to claim 1, wherein the epoxy resin (A) contains an epoxy resin that is solid at room temperature, and the content of the epoxy resin that is solid at room temperature is 50 mass% or more based on the total amount of the epoxy resin (A).

12. The compound according to claim 1, wherein said magnetic particles (C) are rare earth magnetic particles.

13. A compound comprising an epoxy resin (A), magnetic particles (C), and a curing agent (D), wherein the curing agent (D) is an encapsulated curing agent.

14. The compound of claim 13, further comprising a curing agent (B).

15. The compound according to claim 13, wherein the core component of the curing agent (D) is a solid, the curing agent (D) comprises an amine-epoxy adduct, and the amine-epoxy adduct comprises an adduct of an imidazole compound and a bisphenol A type epoxy resin.

16. A varnish comprising an epoxy resin (A), a curing agent (B), a curing agent (D), and an organic solvent (E), wherein the curing agent (D) comprises a capsule-type curing agent, a core component of the curing agent (D) is solid, the curing agent (D) comprises an amine-epoxy adduct, and the amine-epoxy adduct comprises an adduct of an imidazole compound and a bisphenol A type epoxy resin.

17. A bonded magnet obtained by molding and curing the compound according to any one of claims 1 to 15.

18. A motor including the bonded magnet according to claim 17.

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