Compounds, varnishes, bonded magnets and motors

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

[Technical Field]

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

[0002] A bonded magnet is a molded body made by mixing magnetic particles with binders such as resin components and processing them 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 motors for automobiles, general home appliances, communication and audio equipment, medical equipment, general industrial equipment, etc. On the other hand, these motors are expected to have higher rotation speeds in anticipation of higher output, and bonded magnets that are subjected to strong centrifugal forces tend to be required to have 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6606908 Summary of the Invention [Problem to be solved by the invention]

[0005] Bonded magnets are molded by applying heat and pressure to a composite material called a "compound" made by mixing magnetic particles with binders such as resin components. Compression molding compounds use thermosetting resins as their resin components, which provide excellent heat resistance. However, the curing reaction of the resin components continues even during storage, often resulting in storage stability issues. Compression molding requires heating to accelerate the curing reaction of the thermosetting resin, but the magnetic particles in the compound are sensitive to heat, and in a heated environment, the surface of the magnetic particles oxidizes, easily resulting in a deterioration of magnetic properties. Therefore, there is a demand for a compound that has high fixing strength to metal members even when the thermosetting resin is reacted under low temperature conditions (for example, 150° C. or less). 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. [Means for solving the problem]

[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 calorific curve of the compound at a heating rate of 2°C / min, and (Y) is 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, and (X) and (Y) satisfy the following formulas (1) and (2): 100≦(X)≦200 (1) (X)-(Y)≧3 (2) <2> The curing agent (D) includes a capsule-type curing agent. <1> The compound described in <3> The content of the curing agent (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). <1> or <2> The compound described in <4> The core component of the curing agent (D) is solid. <2> or <3> The compound described in <5> The curing agent (D) includes an amine-epoxy adduct. <1> ~ <3> 1. The compound according to any one of the preceding items. <6> The amine-epoxy adducts include an adduct of an imidazole compound and a bisphenol A type epoxy resin. <5> The compound described in <7> Also contains a curing agent (B) <1> ~ <6> 1. The compound according to any one of the preceding items. <8> 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). <7> The compound described in <9> The epoxy resin (A) contains a structure represented by the following formula (A1): <1> ~ <8> 1. The compound according to any one of the preceding items.

[0009] [ka]

[0010] (In formula (A1), R1 to R3 each independently represent 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 includes a group reactive with the curing agent (D), and R1 to R3 may be the same or different from one another.) <10> The epoxy resin (A) contains a structure represented by the following formula (A2): <1> ~ <9> 1. The compound according to any one of the preceding items.

[0011] [ka]

[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 greater. 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 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). <1> ~ <10> 1. The compound according to any one of the preceding items. <12> The magnetic particles (C) are rare earth magnetic particles. <1> ~ <11> 1. The compound according to any one of the preceding items. <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> Also contains a curing agent (B) <13> The compound described in <15> 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. <13> or <14> The compound described in <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> <1> ~ <15> 2. A bonded magnet obtained by molding and curing the compound according to any one of claims 1 to 11. <18> <17> A motor including the bonded magnet according to claim 1. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 shows a test piece for fixation strength. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following 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 practiced by appropriately modifying it within the scope of its gist.

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

[0018] <Embodiment A> The compound of embodiment A is a compound comprising an epoxy resin (A), magnetic particles (C), and a curing agent (D), In differential scanning calorimetry, the peak temperature of the heat curve at a compound temperature rise rate of 2°C / min is (X). When the compound is pressurized at 200 MPa for 5 minutes and the temperature rise rate is 2°C / min, the peak temperature of the heat curve 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 comprises an epoxy resin (A), magnetic particles (C), and a curing agent (D). The mixture of epoxy resin (A) and curing agent (D) (hereinafter referred to simply as the "resin composition") undergoes a curing reaction upon heat treatment, and not only does it bond strongly to the magnetic particles (C), but it also exhibits high fixing strength to metal components.

[0020] (Formula (1)) The compound of embodiment A is In differential scanning calorimetry, when the temperature of the compound at the peak of the exothermic curve at a temperature rise rate of 2°C / min 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 reasons for this are 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 caused by heating the compound. The exothermic peak temperature (X) can be regarded as an index showing the reactivity of the resin composition. If the value of (X) is 100 or more, the curing reaction of the resin composition will not proceed during storage of the compound (usually at 40°C or below), improving the storage stability of the compound. On the other hand, if the value of (X) is 200 or less, the resin composition will sufficiently cure even when heated under low-temperature conditions (for example, 150°C or below), improving the fixing strength to the metal member. 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. As a method for controlling the exothermic peak temperature (X), there is a method for adjusting the exothermic peak temperature (X) by changing the type and amount of the curing agent.

[0022] (Formula (2)) The compound of embodiment A is In differential scanning calorimetry, the peak temperature of the heat release curve at a compound heating rate of 2°C / min is (X). When the compound is pressurized at 200 MPa for 5 minutes and the temperature rise rate is 2°C / min, the peak temperature of the heat curve 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 involves the following steps: (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 high levels of both storage stability and fixing strength when cured at low temperatures. Specifically, this can be achieved by (1) suppressing the reactivity of the resin composition during compound preparation and storage, and (2) increasing the reactivity of the resin composition during compression molding of the compound and (3) heat curing of the molded product. As a method for arbitrarily controlling the reactivity of a resin composition, (2) the pressure (usually 200 MPa or more) that the compound receives in the mold cavity during the compression molding process of the compound can be used to increase the reactivity of the resin composition.

[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 amount of magnetic particles added.

[0027] As mentioned above, the value of (X)-(Y) can be controlled by, for example, using 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 comprises an epoxy resin. The epoxy resin is not limited to the following, but examples thereof include biphenyl type epoxy resins, stilbene type epoxy resins, diphenylmethane type epoxy resins, sulfur atom-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, glycidyl ethers of paraxylylene and / or metaxylylene modified phenolic resins, and the like. 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 olefin bonds with peracids 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] [ka]

[0030] (In formula (A1), R1 to R3 each independently represent 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 includes a group reactive with the curing agent (D), and R1 to R3 may be the same or different from one another.)

[0031] [ka] (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 greater. 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] [ka]

[0034] (In formula (A1), R1 to R3 each independently represent 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 includes a group reactive with the curing agent (D), and R1 to R3 may be the same or different from one another.)

[0035] [ka] (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 greater. 1 and G 2is 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.)

[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] [ka]

[0038] (In formula (A1), R1 to R3 each independently represent 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 includes a group reactive with the curing agent (D), and R1 to R3 may be the same or different from one another.)

[0039] [ka] (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 greater. 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, for example, 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, 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, and Epicron HP-6000. Examples of such surfactants include Clon HP-6000 and N500P-2 (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-502H, EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, and BREN-10S (trade names manufactured by Nippon Kayaku Co., Ltd.), and YX-4000, YX-4000H, YL4121H, and YX-8800 (trade names manufactured by Mitsubishi Chemical Corporation).

[0042] The epoxy resin (A) in embodiment A preferably comprises 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 the epoxy resin. The content of the epoxy resin that is solid at room temperature is preferably 100% by mass or less, and more preferably 99% by mass or less, based on the total amount of the epoxy resin. When the epoxy resin satisfies the above-mentioned constitution, the value of (X)-(Y) can be easily controlled within a desired range, which increases the fixing strength during low-temperature curing and also suppresses blocking of the compound.

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

[0044] The epoxy resin content is preferably 0.5% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 2% by mass to 10% by mass, based on 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 mechanical strength.

[0045] <Curing agent (B)> The compound of embodiment A preferably includes a curing agent (B) that is different from 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 phenol resin is preferably a novolac type phenol resin from the viewpoint of increasing 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 constituting novolac phenolic resins include phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. Examples of naphthols constituting novolac phenolic resins include α-naphthol, β-naphthol, and dihydroxynaphthalene. Examples of aldehydes constituting 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, relative to 1 equivalent of the epoxy group in the epoxy resin. When the ratio of active groups 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 comprises 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 constitution, it becomes easy to control the value of (X) - (Y) within a desired range, and the fixing strength during low-temperature curing can be increased and blocking of the compound can be suppressed.

[0052] The content of the 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, based on the total volume of the compound. By ensuring that the content of the curing agent (B) satisfies the above range, the mechanical strength of the bonded magnet can be increased. The content of the 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, based on the total mass of the compound. By keeping the content of the curing agent (B) within this range, it is possible to achieve both good mechanical strength of the bonded magnet.

[0053] <Magnetic particles (C)> The compound of embodiment A includes magnetic particles. The magnetic particles may be used singly or in combination of two or more types. When two or more types of magnetic particles are mixed, the two or more types of magnetic particles may be mixed and used, differing in alloy composition, particle size (particle size distribution), shape, properties (isotropy, anisotropy), surface treatment, etc.

[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 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 magnetic particles.

[0055] The magnetic particles of embodiment A are preferably rare earth magnetic particles. Rare earth magnetic particles have superior coercive force and magnetic flux density compared to other magnetic particles, and can increase the magnetic force of bonded magnets, 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, which is 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 perspective 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 according to 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 more preferably 1 μm or more and 20 μm or less. The fine particles can increase the filling amount of magnetic particles, thereby improving the magnetic properties. The average particle size and particle size distribution of the magnetic particles are measured using a laser diffraction particle size distribution measuring device (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 includes 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 adduct compounds such as amine-epoxy adducts and amine-urea adducts, capsule-type curing agents obtained by coating these compounds, and curing agents adsorbed on porous bodies. From the viewpoint of the 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 the 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, the shell constituting the capsule-type curing agent preferably contains a synthetic resin. The core is preferably solid at room temperature from the viewpoint of storage stability, but is not limited to the following. 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 to contain an amine-epoxy adduct, and it is more preferable to contain 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] The isocyanate compound is not limited to the following, but examples thereof include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aliphatic triisocyanates, and polyisocyanates. Examples of the aliphatic diisocyanate include, but are not limited to, ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. 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, and 1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane. 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 the aliphatic triisocyanate include, but are not limited to, 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyl octane, and 1,3,6-triisocyanate methyl hexane. 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, and aromatic amines. 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 the compound having at least one hydroxyl group include alcohol compounds and phenol compounds. 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 alcohol, methyl glycerin ... Examples of the polyhydric alcohols 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, which are 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 alcohols, secondary alcohols, 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 polyphenols such as catechol, resorcinol, hydroquinone, bisphenol A, bisphenol F, pyrogallol, phloroglucin, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol. From the viewpoint of latency and solvent resistance, the compounds having at least one hydroxyl group are preferably polyhydric alcohols and polyhydric phenols, 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 (isocyanate group in the isocyanate compound):(active hydrogen in the active hydrogen compound) (equivalent ratio) is preferably in the range of 1:0.1 to 1:1000.

[0082] Examples of imidazole compounds 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, per 100 parts by mass of epoxy resin (A). By ensuring that 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 the 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 the epoxy resin (A). By ensuring that the content of the 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 compound's releasability 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-hydroxystearic acid, calcium ricinoleate, stearamide, oleamide, erucamide, behenamide, palmitamide, lauric amide, hydroxystearamide, methylene bisstearamide, ethylene bisstearamide, ethylene bislauric amide, distearyl adipamide, ethylene bisoleamide, dioleyl adipamide, N-stearyl stearamide, N-oleyl stearamide, N-stearyl erucamide, methylol stearamide, methylol behenamide, 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, which can further increase the adhesion between the resin composition and the surfaces of the magnetic particles, thereby further increasing the strength of the bonded magnet. Examples of the coupling agent include coupling agents of silane-based compounds such as epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, and vinylsilane; coupling agents of titanium-based compounds; coupling agents of aluminum chelates; and coupling agents of 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 consist of one type of particle, or may 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, which 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. The inclusion of a flame retardant can improve the fire resistance of the compound. 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 that constitutes the magnetic particles is coated with the varnish, thereby obtaining 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 that are preferred are 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), and the curing agent (D) is an encapsulated curing agent. The compound of embodiment B preferably comprises a curing agent (B) that is different from the hardener (D). The core component of the curing agent (D) is solid and preferably comprises an amine-epoxy adduct.

[0094] Details of specific examples, preferred specific 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 the details of specific examples, preferred specific examples, preferred contents, preferred aspects, etc. of the epoxy resin (A), curing agent (B), magnetic particles (C), and curing agent (D) in embodiment A described above. Details of the curing agent (D), such as specific examples, preferred specific examples, preferred content, and preferred aspects, are the same as the details of the curing agent (D), such as specific examples, preferred specific examples, preferred content, and preferred aspects, in embodiment A described above. <Varnish> The varnish of this embodiment is a varnish containing an epoxy resin (A), a curing agent (B), a curing agent (D), and an organic solvent (E), where 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 compound for bonded magnets, which will be described later.

[0095] <Compound manufacturing method> The method for producing the compound of this embodiment is not particularly limited, but examples include a method of mixing the resin composition at a temperature above the melting point (hereinafter simply referred to as "melt mixing"), and a method of dissolving the resin composition in a solvent and mixing it (hereinafter simply referred to as "dissolution mixing").

[0096] The melt mixing may be carried out by the following method. The compound raw materials (epoxy resin, curing agent, magnetic particles, and other additives) are thoroughly mixed in a mixer to obtain a mixed powder of the compound raw materials. The obtained mixed powder of the compound raw materials is heated and mixed at a temperature equal to or higher than the softening temperature of the resin composition, and the solid matter is crushed as needed to obtain the compound. The heating and mixing temperature varies depending on the type and amount of the resin composition, but is preferably from 40° C. to 140° C., and more preferably from 60° C. to 120° C. By heating and mixing within the above temperature range, the curing reaction of the resin composition can be suppressed while improving the dispersibility of the materials in the compound. The mixing device is not particularly limited, but for example, a heat kneader can be used. In this case, the dispersibility of the 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. A resin composition solution (varnish) is obtained by dissolving the raw materials of the resin composition, such as epoxy resin and curing agent, in an organic solvent. Magnetic particles are added to the resin composition solution to disperse the magnetic particles in the resin composition solution, and the organic solvent is then removed from the solution containing the magnetic particles and 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, and more preferably 40°C or less.

[0099] <Manufacturing method of bonded magnets> The bonded magnet of this embodiment is a bonded magnet obtained by molding and hardening a compound. The compound is filled into a mold and then compressed to produce a green body. The higher the molding pressure, the higher the density of the bonded magnet, but the more likely the magnetic particles are to 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 hardens, 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 hardened. Furthermore, from the viewpoint of suppressing oxidation of the magnetic particle surface, low-temperature hardening and short-time hardening are preferred. The hardening temperature is, for example, preferably 200°C or less, more preferably 180°C or less, and even more preferably 150°C or less. The hardening 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 heat treatment of the compact. The bonded magnet of this embodiment can be preferably used for a motor. The motor of this embodiment includes the bonded magnet of this embodiment. [Example]

[0102] Hereinafter, the present embodiment will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to the following 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] [Table 1]

[0105] (Hardening 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] [Table 2]

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

[0108] [Table 3]

[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] [Table 4]

[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 in a 1:1 mixed solvent of n-butanol and toluene at 80°C. After that, excess amine was distilled off together with the solvent under reduced pressure, and a solid block curing agent 1 was obtained at 25°C. Block-shaped curing agent 1 was roughly crushed to about 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). Next, the crushed material was classified using an air classifier "Turbo Classifier" (manufactured by Nisshin Engineering Inc.) to obtain a curing agent (D-1) that was solid 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 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 an encapsulated curing agent (D-2) dispersed in the epoxy resin.

[0113] [Preparation of bonded magnet compound] Example 1 A resin solution was prepared by mixing 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 in a 300 mL eggplant flask and stirring for an additional 30 minutes. 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 in the evaporator was then reduced to 0.1 MPa or less, completely removing the solvent from the flask. During the solvent removal process, the following steps were repeated several times in order to thoroughly remove the solvent: reducing the pressure in the flask, restoring the flask to normal pressure, and loosening the aggregated contents in the flask. After the solvent was removed, 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 in a vacuum dryer at room temperature for 8 hours. After drying, the aggregated mixture was coarsely pulverized to obtain a bonded magnet compound (CPD-1). The resulting bonded magnet compound was subjected to 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 that shown in Table 5. Evaluation was 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 vessel, and the mixture was stirred and mixed using a planetary 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 mixed by stirring with a rotation-revolution 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 using a DSC measuring device, Q2000, manufactured by TA Instruments, from 25 to 250°C at 2°C / min to obtain calorimetry curves. For the obtained calorimetry curves, the exothermic peak temperature at which the calorific value 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 calorimetry curves for the samples, and the exothermic peak temperature at which the heat generation was greatest was taken 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) The bonded magnet compounds of each example and comparative example were filled into a powder molding die (manufactured by LabNect Co., Ltd.) with a diameter of 10.0 mm, and pressed at 200 MPa for 1 minute to mold a pellet with a thickness of 1.0 mm. The pellets were 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 heated and pressed using a hydraulic molding machine TM-10 (manufactured by Toho Machinery Co., Ltd.) to prepare test specimens. The heating conditions for the hydraulic molding machine were 150°C for 30 minutes and the compression conditions were 200 MPa. The fixed position of the pellets relative to the test specimen is shown in Figure 1. The obtained test specimens were subjected to 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 fixed surface of the test specimen broke and the test specimen separated. The maximum load at which the specimen separated was divided by the adhesive area to obtain the fixation strength. A, B, and C ranks were considered passing. <Evaluation criteria> A: Fixing strength is 1200N / mm 2 That was all. B: Fixing strength is 1000N / mm 2 More than 1200N / mm 2 It was less than. C: Fixing strength is 800N / mm 2 More than 1000N / mm 2 It was less than. D: Fixing strength is 600N / mm 2 More than 800N / mm 2 It was less than. E: Fixing strength is 600N / 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 it, 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 it, the fixing strength reduction rate was calculated using the following formula (3) and used as an index of storage stability. Fixing strength reduction rate = Fixing strength to steel plate after 7 days at 40°C / Fixing strength to steel plate × 100 (3) A, B, and C ranks were considered passing. <Evaluation criteria> A: The reduction in the fixing strength to the steel plate was less than 10.0%. B: The rate of decrease in fixing strength to the steel plate was 10.0% or more and less than 15.0%. C: The reduction rate of the fixing strength to the steel plate was 15.0% or more and less than 20.0%. D: The reduction rate of the fixing strength to the steel plate was 20.0% or more and less than 25.0%. E: The reduction rate of the fixing strength to the steel plate was 25.0% or more.

[0121] (Blocking property) The 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. A and B ranks were considered passing. <Evaluation criteria> A: No change was observed in the particle size of the compound. B: The compound was seen to be united, but it came apart when touched with the fingers. C: The compound was seen to be united and could not be loosened even when touched with fingers. D: The compound had united 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] [Table 5]

[0124] [Table 6]

[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, where (X) is the exothermic peak temperature of the calorific curve at a heating rate of 2°C / min of the compound and (Y) is the exothermic peak temperature of the calorific curve at a heating rate of 2°C / min after the compound is pressurized at 200 MPa for 5 minutes, Examples using compounds in which (X) and (Y) satisfy formulas (1) and (2) respectively, had excellent storage stability and showed high fixing strength to metal members even when the thermosetting resin was subjected to a curing reaction under low-temperature conditions. On the other hand, the comparative examples in which (X)-(Y) was less than 3 had poor storage stability and poor fixing strength to the metal member when the thermosetting resin was subjected to a curing reaction 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), In differential scanning calorimetry, the heat generation peak temperature of the heat curve of the bonded magnet compound at a heating rate of 2°C / min is (X), When the heat generation peak temperature of the heat curve at a temperature rise rate of 2°C / min after the bonded magnet compound is pressurized at 200 MPa for 5 minutes is defined as (Y), A bonded magnet compound in which (X) and (Y) satisfy the following formulas (1) and (2). 100≦(X)≦200 (1) (X)-(Y)≧3 (2) <2> The epoxy resin (A) includes an epoxy resin that is solid at room temperature, The content of the epoxy resin is 50% by mass or more based on the total amount of the epoxy resin. <1> 2. The bonded magnet compound according to claim 1. <3> The curing agent (B) includes a curing agent that is solid at room temperature, The content of the curing agent is 50% by mass or more based on the total amount of the curing agent. <1> or <2> 2. The bonded magnet compound according to claim 1. <4> The content of the magnetic particles (C) is 40% by volume or more and 95% by volume or less based on the total volume of the bonded magnet compound. <1> ~ <3> 10. The bonded magnet compound according to any one of claims 1 to 9. <5> The magnetic particles (C) are rare earth magnetic particles. <1> ~ <4> 10. The bonded magnet compound according to any one of claims 1 to 9. <6> The curing accelerator (D) contains a microcapsule-type latent accelerator. <1> ~ <5> 10. The bonded magnet compound according to any one of claims 1 to 9. <7> 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). <1> ~ <6> 10. The bonded magnet compound according to any one of claims 1 to 9. <8> A bonded magnet compound comprising an epoxy resin (A), a curing agent (B), magnetic particles (C), and a curing accelerator (D), A bonded magnet compound, 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. [Industrial Applicability]

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

[0129] 1 pellet 2 steel plate

Claims

1. A compound comprising an epoxy resin (A), magnetic particles (C), and a curing agent (D), In differential scanning calorimetry, the exothermic peak temperature of the calorie curve at a temperature rise rate of 2 ° C. / min of the compound is (X), When the compound is pressurized at 200 MPa for 5 minutes and then the exothermic peak temperature of the calorific curve at a temperature rise rate of 2°C / min is defined as (Y), A compound in which (X) and (Y) satisfy the following formulas (1) and (2). 100≦(X)≦200...(1) (X)-(Y)≧3...(2)

2. 10. 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. 3. The compound of claim 2, wherein the core component of the curing agent (D) is a solid.

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

6. 6. The compound of claim 5, wherein the 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 curing agent (B) includes a curing agent that is solid at room temperature, The compound according to claim 7, wherein 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): 【Chemistry 1】 (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.)

10. The compound according to claim 1, wherein the epoxy resin (A) comprises a structure represented by the following formula (A2): 【Chemistry 2】 (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.)

11. The epoxy resin (A) includes an epoxy resin that is solid at room temperature, The compound according to claim 1, wherein 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. 2. The compound according to claim 1, wherein the magnetic particles (C) are rare earth magnetic particles.

13. A bonded magnet obtained by molding and curing the compound according to any one of claims 1 to 12.

14. A motor including the bonded magnet of claim 13.

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