Compound

Abstract

This compound contains a magnetic powder and a resin composition. The magnetic powder is an alloy containing samarium, iron, and nitrogen. The resin composition contains an epoxy resin and one or more capsules containing an amine (curing agent). Since the capsule contains the amine, curing of the compound is suppressed during storage of the compound.

Description

Compound

[0001] The present disclosure relates to compounds.

[0002] Sm—Fe—N permanent magnets (samarium-iron-nitrogen permanent magnets) can be produced from cheaper raw materials than other rare earth magnets such as Nd—Fe—B permanent magnets (neodymium-iron-boron permanent magnets), and they have excellent magnetic properties. However, the crystal structure of Sm—Fe—N permanent magnets is prone to deterioration at high temperatures (approximately 500°C), making it difficult to produce sintered magnets from them. Therefore, Sm—Fe—N permanent magnets are used as raw materials for anisotropic bonded magnets, which can be produced by heating at low temperatures (thermal curing of thermosetting resins mixed with magnet powder) at which the crystal structure is maintained.

[0003] The raw material for anisotropic bonded magnets is a compound containing magnet powder (numerous magnet particles consisting of permanent magnets) and a thermosetting resin (see Patent Document 1 below). In manufacturing anisotropic bonded magnets, the compound is fed into a mold. The compound in the mold is heated and compressed while a magnetic field generated by a coil is applied to the compound in the mold. After the compound is heated and compressed, an anisotropic bonded magnet made from the hardened compound is manufactured. Each magnet particle in the anisotropic bonded magnet (magnetic domains in each magnet particle) is magnetized and oriented along the magnetic field.

[0004] Patent No. 7298804

[0005] If the thermosetting resin in the molded body formed in the mold is not cured sufficiently, the molded body is likely to break when it is removed from the mold. Furthermore, if the thermosetting resin in the molded body is not cured sufficiently, it is difficult to increase the bulk density of the molded body, and it is also difficult to increase the residual magnetic flux density of the final bonded magnet. The longer the molded body is heated in the mold, the more rapidly the thermosetting resin in the mold is cured. Therefore, the longer the molded body is heated and compressed in the mold, the more likely it is that damage to the molded body will be suppressed, the more likely the bulk density of the molded body will increase, and the more likely the residual magnetic flux density of the bonded magnet will increase. However, the longer the molded body is heated and compressed in the mold, the lower the productivity of the bonded magnet.

[0006] According to the inventors' research, amines (e.g., imidazoles) are curing agents that can cure epoxy resins more quickly than conventional curing agents (e.g., phenolic curing agents). However, the epoxy resin and amines in the compound tend to react with each other during storage. This means that the compound's hardening can unintentionally proceed during storage. For example, the amines can cause the epoxy resin in the compound to harden before the compound is molded (heated and compressed). As a result, it is difficult to form a dense molded body (bonded magnet) during the molding process. For these reasons, it is difficult to produce bonded magnets with high bulk density and high residual magnetic flux density from conventional compounds containing epoxy resins and amines.

[0007] An object of one aspect of the present invention is to provide a compound that inhibits hardening of the compound during storage and that increases the residual magnetic flux density of a bonded magnet produced from the compound.

[0008] For example, one aspect of the present invention relates to a compound described in any one of [1] to

[11] below.

[0009] [1] A compound comprising a magnet powder and a resin composition, wherein the magnet powder is an alloy containing samarium, iron, and nitrogen, and the resin composition includes an epoxy resin and one or more capsules containing an amine.

[0010] [2] The compound according to [1], wherein the amine includes at least one selected from imidazoles.

[0011] [3] The compound according to [1], wherein the amine is at least one selected from the group consisting of 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 1-aminopropyl-2-methylimidazole.

[0012] [4] The compound according to any one of [1] to [3], wherein the one or more capsules contain polyurethane.

[0013] [5] The compound according to any one of [1] to [3], wherein the one or more capsules contain polyurethane formed from one or more isocyanates selected from the group consisting of tolylene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene phenylene polyisocyanate, n-octadecyl isocyanate, 1,6-hexamethylene diisocyanate, cyclohexyl isocyanate, n-dodecyl isocyanate, and n-hexadecyl isocyanate.

[0014] [6] The compound according to any one of [1] to [5], wherein the epoxy resin is at least one selected from the group consisting of biphenyl-type epoxy resins, dicyclopentadiene-type epoxy resins, naphthalene-type epoxy resins, and cresol novolac-type epoxy resins.

[0015] [7] The compound according to any one of [1] to [6], which does not contain a phenol-based curing agent.

[0016] [8] The compound according to [7], wherein the phenol-based curing agent is at least one selected from the group consisting of phenolic resins and phenolic novolac resins.

[0017] [9] The compound according to any one of [1] to [8], which is in the form of a powder, a tablet, or a paste.

[0018]

[10] The compound according to any one of [1] to [9], which is a raw material for a bonded magnet.

[0019]

[11] The compound according to any one of [1] to [9], which is a raw material for an anisotropic bonded magnet in which the magnetization direction of each of the plurality of magnetic particles constituting the magnetic powder is aligned.

[0020] According to one aspect of the present invention, there is provided a compound that inhibits hardening of the compound during storage and increases the residual magnetic flux density of a bonded magnet produced from the compound.

[0021] Fig. 1 is a schematic cross-sectional view of a capsule in a compound according to one embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view of one embodiment of a bonded magnet produced from the compound.

[0022] (Outline of Compound and Bonded Magnets) Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, equivalent components are designated by equivalent reference numerals. The present invention is not limited to the following embodiments. X, Y, and Z shown in Figure 2 represent three coordinate axes that are orthogonal to each other.

[0023] The compound according to this embodiment includes a magnet powder and a resin composition. The compound may be referred to as a mixture including the magnet powder and the resin composition. The compound may be in the form of a powder, tablet, or paste at room temperature (e.g., 20°C ± 15°C). The compound according to this embodiment may be a raw material for a bonded magnet (e.g., an anisotropic bonded magnet).

[0024] The magnet powder is an alloy containing samarium (Sm), iron (Fe), and nitrogen (N). The magnet powder may be rephrased as a large number of magnet particles made of an alloy containing samarium, iron, and nitrogen. The alloy containing samarium, iron, and nitrogen may be rephrased as an Sm—Fe—N permanent magnet. The Sm—Fe—N permanent magnet may have anisotropy. In other words, each magnet particle (magnetic domain within each magnet particle) constituting the magnet powder, which is an Sm—Fe—N permanent magnet, may have an easy axis of magnetization (crystal axis) extending in one direction.

[0025] The resin composition includes at least an epoxy resin and one or more capsules (e.g., microcapsules). As shown in FIG. 1, one or more capsules 7 contain an amine 6. In other words, some or all of the amine 6 contained in the resin composition is encapsulated by one or more capsules 7. Epoxy resin is a type of thermosetting resin. An amine is a curing agent that cures epoxy resins. For example, an addition reaction between an epoxy resin (epoxy group) and an amine (amino group) may promote amine-mediated polymerization of the epoxy resin, polymerization or crosslinking between epoxy resins. Amines are superior to other curing agents (e.g., phenolic curing agents) in that they can cure epoxy resins more quickly. An amine may be referred to as a compound having at least one tertiary amino group and at least one active hydrogen group. In other words, an amine may be a tertiary amine having at least one active hydrogen group in its molecular structure. In this disclosure, amine implies imidazole. In this disclosure, one or more capsules 7 containing amine 6 are referred to as a "capsule-type curing agent."

[0026] Because the amine is encapsulated in one or more capsules, the amine and the epoxy resin are unlikely to come into contact with each other in the compound unless the capsules rupture, thereby inhibiting reaction between the amine and the epoxy resin. Therefore, by storing the compound in a state in which the capsules in the compound do not rupture, hardening of the compound (thermal hardening of the epoxy resin) during storage is inhibited. In other words, because the amine is encapsulated in one or more capsules, the properties of the compound during storage tend to be stable, and the compound can be stored in an uncured state for a long period of time.

[0027] The capsules rupture as the compound is heated or compressed during the manufacturing process of the bonded magnet (e.g., molding process). As the capsules rupture, the amine seeps out from the inside of the capsule to the outside of the capsule. As a result, the amine and the epoxy resin come into contact with each other in the compound, and the thermal curing of the epoxy resin progresses. For example, the capsules may rupture due to the thermal expansion of the amine inside the capsules during the molding process. For example, the capsules may rupture due to the pressure applied to the capsules during the molding process.

[0028] Some or all of the epoxy resin in the compound may be uncured (uncured epoxy resin). Some or all of the epoxy resin in the compound may be semi-cured (B-stage epoxy resin). Some of the epoxy resin in the compound may be uncured, and the remainder of the epoxy resin in the compound may be semi-cured. By thermally curing the epoxy resin, the multiple magnet particles contained in the compound are bound to each other by the cured epoxy resin. In other words, the epoxy resin functions as a binding material (binder) that binds the multiple magnet particles that make up the magnet powder together.

[0029] The bonded magnet according to this embodiment includes a hardened compound. The bonded magnet may consist solely of a hardened compound. For example, as shown in FIG. 2, the bonded magnet according to this embodiment may be an anisotropic bonded magnet (2A) in which the magnetization direction m of each of the multiple magnetic particles 3 that make up the magnetic powder is aligned. However, the magnetization direction of each of the multiple magnetic particles in the bonded magnet does not have to be aligned.

[0030] Phenolic curing agents are well known as a representative example of conventional curing agents for curing epoxy resins. However, contrary to conventional wisdom, compounds containing an amine but not a phenolic curing agent can be sufficiently cured in a shorter time than compounds containing both a phenolic curing agent and an amine. Furthermore, compounds containing an amine but not a phenolic curing agent can be sufficiently cured in a shorter time than compounds containing a phenolic curing agent and a conventional curing agent other than an amine (compounds without an amine). For example, the conventional curing agent other than a phenolic curing agent and an amine may be at least one curing agent selected from the group consisting of organic phosphoric acid, organic phosphate, organic boric acid, and organic borate. Furthermore, compounds containing an amine but not a phenolic curing agent can be sufficiently cured in a shorter time than conventional compounds containing a phenolic curing agent but not an amine. For these reasons, it is preferable that the compound according to this embodiment does not contain a phenolic curing agent. However, the compound according to this embodiment may contain a phenolic curing agent.

[0031] Because the melt viscosity of phenolic curing agents tends to be higher than that of epoxy resins, the melt viscosity at molding temperature T (e.g., 150°C) of a resin composition containing a phenolic curing agent as a curing agent tends to be higher than that of a resin composition not containing a phenolic curing agent. As a result, compounds containing a phenolic curing agent tend to flow less easily in a mold than compounds not containing a phenolic curing agent. Therefore, the bulk density, mechanical strength, and residual magnetic flux density of bonded magnets formed from compounds containing a phenolic curing agent tend to be lower than those of bonded magnets formed from compounds not containing a phenolic curing agent. Therefore, it is preferable that the compound according to this embodiment does not contain a phenolic curing agent, as this facilitates the flow of the compound during the molding process at molding temperature T.

[0032] Because the compound according to the present embodiment contains an amine, when the compound according to the present embodiment and another compound not containing an amine are heated at the same temperature, the epoxy resin in the compound according to the present embodiment tends to cure sufficiently in a shorter time than the epoxy resin in the other compound. As a result, the bulk density and mechanical strength of a bonded magnet (green body) formed from the compound according to the present embodiment tend to be higher than those of a bonded magnet formed from another compound. Since the remanence of a bonded magnet increases as the bulk density of a bonded magnet increases, the remanence of a bonded magnet formed from the compound according to the present embodiment tends to be higher than those of a bonded magnet formed from another compound. For example, when a bonded magnet (green body) is formed from the compound according to the present embodiment by heating and compressing it in a mold, the bulk density and mechanical strength of the bonded magnet formed in the mold tend to be sufficiently high. As a result, damage and deformation of the bonded magnet that accompanies removal from the mold is suppressed, and the bulk density, mechanical strength, and residual magnetic flux density of the final bonded magnet are likely to be increased. Because the compound according to this embodiment hardens in a shorter time than other compounds, the time required to heat and compress the compound in the mold is shorter than conventional methods, the occurrence of defective products in the molding process is suppressed, and the yield rate of bonded magnets is increased. As a result, the productivity of bonded magnets is improved.

[0033] (Compound Details) <Resin Composition Comprising Epoxy Resin and Capsule-Type Curing Agent> In the present invention, the term "resin composition" refers to the remaining portion (non-volatile components) of the compound excluding the magnet powder. The resin composition contains at least an epoxy resin and a capsule-type curing agent (one or more capsules containing an amine). For the reasons described above, it is preferable that the resin composition does not contain a phenolic curing agent. However, the resin composition may contain a phenolic curing agent. The resin composition may further contain at least one component selected from the group consisting of a coupling agent, a wax (lubricant), a reactive diluent, and a flame retardant. The compound may further contain an organic solvent in addition to the magnet powder and the resin composition. The resin composition may consist only of an epoxy resin and a capsule-type curing agent. The compound may also consist only of a magnet powder and the resin composition.

[0034] The resin composition containing the epoxy resin and capsule-type curing agent functions as a binder that binds together the multiple magnet particles that make up the magnet powder. In other words, the resin composition imparts mechanical strength to the bonded magnet produced from the compound. For example, the resin composition filled between the multiple magnet particles binds them together. Furthermore, by thermally curing the resin composition, the cured resin composition binds the multiple magnet particles together even more firmly.

[0035] The mass of the magnet powder in the compound may be expressed as Mm (unit: g). The mass of the entire resin composition in the compound may be expressed as Mr (unit: g). The content (unit: mass%) of the magnet powder in the compound may be defined as Mm / (Mm+Mr) x 100. The content (unit: mass%) of the resin composition (e.g., epoxy resin and capsule-type hardener) in the compound may be defined as Mr / (Mm+Mr) x 100. Because the bonded magnet produced from the compound tends to have high bulk density, mechanical strength, and residual magnetic flux density, the content of the magnet powder in the compound may be 90.0% by mass or more and 99.9% by mass or less, preferably 95.0% by mass or more and 99.5% by mass or less, and more preferably 96.0% by mass or more and 98.0% by mass or less. As the content of the magnetic powder increases, the bulk density and residual magnetic flux density of the anisotropic bonded magnet tend to increase. As the content of the magnetic powder decreases, the mechanical strength of the anisotropic bonded magnet tends to increase. The content of the resin composition in the compound may be 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass or more and 5% by mass or less, and more preferably 2% by mass or more and 4% by mass or less. For example, the total content of the epoxy resin and capsule-type curing agent in the compound may be 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass or more and 5% by mass or less, and more preferably 2% by mass or more and 4% by mass or less. As the content of the resin composition decreases, the bulk density and residual magnetic flux density of the anisotropic bonded magnet tend to increase. As the content of the resin composition increases, the mechanical strength of the anisotropic bonded magnet tends to increase.

[0036] For example, the amine may include at least one selected from the group consisting of imidazole, aliphatic polyamine, polyaminoamide, aromatic polyamine, and dicyandiamide (DICY). That is, the amine encapsulated in one or more capsules may be at least one selected from the group consisting of imidazole, aliphatic polyamine, polyaminoamide, aromatic polyamine, and dicyandiamide (DICY). The amine may include imidazole because it is easy to cure the epoxy resin in a short time. For example, the imidazole may be at least one selected from 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole (4-methyl-2-phenylimidazole), 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-aminopropyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, and 1-cyanoethyl-2-phenylimidazole.

[0037] The relative mass of the amine to 100 parts by mass (100 g) of epoxy resin may be 0.1 to 30 parts by mass (0.1 g to 30 g), 1 to 15 parts by mass (1 g to 15 g), or 1 to 5 parts by mass (1 g to 5 g), because this allows the compound to cure quickly and the bonded magnet produced from the compound to have increased bulk density, mechanical strength, and residual magnetic flux density. As the relative mass of the amine increases, the compound cures more quickly. As the relative mass of the amine decreases, deterioration of the compound during storage (for example, thermal curing of the epoxy resin during storage) is more likely to be suppressed.

[0038] In addition to the amine, the compound may further contain a cure accelerator, for example, at least one compound selected from the group consisting of tetra-substituted phosphonium tetra-substituted borates, polymercaptans, and acid anhydrides.

[0039] The composition of the one or more amine-containing capsules themselves is not limited, as long as the capsules can rupture upon heating or compression of the compound during the molding process. For example, the one or more amine-containing capsules themselves may contain polyurethane. Polyurethane is a polymer (urethane resin) containing a urethane bond represented by —NH—(C═O)O—. The one or more amine-containing capsules themselves may consist solely of polyurethane. Polyurethane-containing capsules are chemically stable in compounds containing epoxy resins, and polyurethane-containing capsules are unlikely to rupture unless the compound is heated and compressed. Therefore, when each amine-containing capsule itself contains polyurethane, the curing of the compound in its unprocessed state is easily inhibited, and the curing of the compound prior to the molding process is also easily inhibited. For example, polyurethane may be formed (synthesized) from one or more isocyanates (monomers). In other words, polyurethane may be a polymer of one or more isocyanates and one or more active hydrogen compounds. Isocyanate is a general term for compounds containing a partial structure represented by —N═C═O. The active hydrogen compound is a compound having active hydrogen. For example, the one or more isocyanates may be selected from the group consisting of tolylene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene phenylene polyisocyanate, n-octadecyl isocyanate, 1,6-hexamethylene diisocyanate, cyclohexyl isocyanate, n-dodecyl isocyanate, and n-hexadecyl isocyanate. For example, the active hydrogen compound may be a polyol such as a diol. An epoxy compound (e.g., bisphenol A-type epoxy resin) may be bonded to or attached to at least one of the outer surface or inner surface of the capsule.

[0040] For example, the shape of each capsule containing the amine may be approximately spherical. In other words, each capsule-type curing agent may be a spherical particle. For example, the average particle size of the capsule-type curing agent may be 0.1 μm or more and 50 μm or less, or 0.5 μm or more and 10 μm or less. When the average particle size of the capsule-type curing agent is 50 μm or less, it is easy to produce a homogeneous bonded magnet (a homogeneous cured product of the compound). For example, the average particle size of the capsule-type curing agent may be the Stokes diameter measured by a light scattering method. For example, the average capsule thickness may be 5 nm or more and 1000 nm or less, or 50 nm or more and 700 nm or less. When the average capsule thickness is 5 nm or more, the properties of the compound are likely to be stable during storage. When the average capsule thickness is 1000 nm or less, the capsules are likely to rupture when the compound is heated or compressed during the molding process. For example, the capsule thickness may be measured using a transmission electron microscope.

[0041] Specific examples of the method for producing a capsule-type curing agent may be as follows. [Specific Example A] A large number of raw material particles (solid) made of amine are dispersed in a solvent (solvent that does not dissolve the raw material particles) containing the capsule raw material (e.g., resin). After the large number of raw material particles are dispersed in the solvent, the solvent is removed or the large number of raw material particles are recovered from the solvent, thereby obtaining a large number of raw material particles covered with the capsule raw material. A large number of capsule-type curing agents are obtained by solidifying the raw material covering each raw material particle (precipitation or hardening of the resin). [Specific Example B] A large number of raw material particles made of amine are dispersed in a solvent (solvent that does not dissolve the raw material particles) containing the capsule raw material (e.g., monomer). After the large number of raw material particles are dispersed in the solvent, the solvent is removed or the large number of raw material particles are recovered from the solvent, thereby obtaining a large number of raw material particles covered with the capsule raw material. A large number of capsule-type curing agents are obtained by solidifying the raw material covering each raw material particle (polymerization of the monomer). [Specific Example C] A large number of raw material particles made of amine are dispersed in a solvent (solvent that does not dissolve the raw material particles) containing the capsule raw material (e.g., resin or monomer). After a large number of raw material particles are dispersed in a solvent, the capsule raw material on the surface of each raw material particle in the solvent solidifies (resin hardening or monomer polymerization), forming a large number of capsule-type curing agents in the solvent. If necessary, the solvent may be removed, and the capsule-type curing agent may be recovered from the solvent. [Specific Example D] A solvent (solvent that does not dissolve raw material particles) is prepared in which a reaction product (polyurethane) of an isocyanate and an active hydrogen compound is dissolved. Furthermore, a large number of raw material particles composed of an amine are dispersed in the solvent. Due to the decrease in the solubility of the reactant in the solvent and the evaporation of the solvent, a coating composed of the reactant precipitates on the surface of each raw material particle. As a result, a large number of capsule-type curing agents are formed in the solvent. [Specific Example E] A solvent (solvent that does not dissolve raw material particles) in which a large number of raw material particles composed of an amine, an isocyanate, and an active hydrogen compound are dispersed is prepared. Due to the reaction of the isocyanate and the active hydrogen compound in the solvent, a coating composed of the reactant (polyurethane) precipitates on the surface of each raw material particle. As a result, a large number of capsule-type curing agents are formed in the solvent. [Specific Example F] A solvent (solvent that does not dissolve the raw material particles) is prepared in which a large number of raw material particles made of amine, isocyanate, and an active hydrogen compound are dispersed.The isocyanate and the active hydrogen compound react on the surface (reaction field) of each raw material particle, and a reaction product (polyurethane) is generated on the surface of each raw material particle. As a result, a large number of capsule-type curing agents are formed in the solvent. If necessary, the solvent may be removed, and the capsule-type curing agent may be recovered from the solvent. For example, the solvent in which the raw material particles, the isocyanate, and the active hydrogen compound are dispersed may be a liquid epoxy resin.

[0042] For example, the epoxy resin may be one having two or more epoxy groups in one molecule. From the viewpoint of improving the heat resistance (mechanical strength at high temperatures) of the bonded magnet, the epoxy resin is preferably a heat-resistant epoxy resin such as a naphthalene-type epoxy resin.

[0043] Examples of epoxy resins include biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-containing epoxy resins, novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins, naphthalene-type epoxy resins, naphthol- and phenol-copolymerized epoxy resins, epoxidized aralkyl-type phenolic resins, bisphenol-type epoxy resins, glycidyl ether-type epoxy resins of alcohols, glycidyl ether-type epoxy resins of paraxylylene-modified phenolic resins and / or metaxylylene-modified phenolic resins, and glycidyl ether-type epoxy resins of terpene-modified phenolic resins. The epoxy resin may be at least one selected from the group consisting of 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 epoxy resins, halogenated phenol novolac-type epoxy resins, cresol novolac-type epoxy resins (orthocresol novolac-type epoxy resins), hydroquinone-type epoxy resins, trimethylolpropane-type epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with a peracid such as peracetic acid. Examples of highly crystalline epoxy resins that may be used include hydroquinone-type epoxy resins, bisphenol-type epoxy resins, thioether-type epoxy resins, and biphenyl-type epoxy resins.

[0044] The epoxy resin may be at least one selected from the group consisting of biphenyl-type epoxy resin, dicyclopentadiene-type epoxy resin, naphthalene-type epoxy resin (naphthylene ether-type epoxy resin), and cresol novolac-type epoxy resin, because the compound flows easily at molding temperature T, the magnetic particles in the compound tend to rotate due to the magnetic field during the molding process at molding temperature T, and the residual magnetic flux density of the bonded magnet produced from the compound tends to increase. The relative mass of the epoxy resin to 100 parts by mass of magnet powder may be 1 part by mass or more and 6 parts by mass or less, because the compound flows easily at molding temperature T, the magnetic particles in the compound tend to rotate due to the magnetic field during the molding process at molding temperature T, and the residual magnetic flux density of the bonded magnet produced from the compound tends to increase.

[0045] At least a portion of the epoxy resin may be a naphthalene-type epoxy resin having a naphthalene structure. Naphthalene-type epoxy resins are solid at room temperature. When the compound contains a naphthalene-type epoxy resin, the bonded magnet tends to have high mechanical strength at room temperature and high temperatures. For example, the naphthalene-type epoxy resin may be at least one epoxy resin selected from the group consisting of naphthalene diepoxy compounds, naphthylene ether-type epoxy resins, naphthalene novolac-type epoxy resins, methylene-bonded dimers of naphthalene diepoxy compounds, and methylene-bonded dimers of naphthalene monoepoxy compounds and naphthalene diepoxy compounds.

[0046] For example, the naphthalene-type epoxy resin is preferably at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin. The naphthalene-type epoxy resin is more preferably a tetrafunctional epoxy resin. When the naphthalene-type epoxy resin contained in the compound is at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin, the naphthalene-type epoxy resins are three-dimensionally crosslinked with each other as the compound is heated during the molding process, forming a strong crosslinked network. As a result, the movement of the naphthalene-type epoxy resin in the bonded magnet is suppressed at high temperatures. In other words, the glass transition temperatures of the trifunctional epoxy resin and the tetrafunctional epoxy resin are higher than the glass transition temperature of the difunctional epoxy resin. Therefore, when the naphthalene-type epoxy resin contained in the compound is at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin, the bonded magnet is likely to have high mechanical strength at high temperatures, and changes in the orientation direction of the magnet powder due to temperature increases are likely to be suppressed.

[0047] For example, a trifunctional naphthalene type epoxy resin or a tetrafunctional naphthalene type epoxy resin is HP-4700 manufactured by DIC Corporation. ＴＭ , HP-4710 ＴＭ , HP-4770 ＴＭ , EXA-5740 ＴＭ , or EXA-7311-G4 ＴＭ The naphthalene type epoxy resin contained in the compound may be a bifunctional epoxy resin. Examples of bifunctional naphthalene type epoxy resins include HP-4032 ＴＭ Or HP-4032D ＴＭ The naphthalene type epoxy resin contained in the compound powder may be a β-naphthol type epoxy resin.

[0048] The compound may contain one of the above epoxy resins. The compound may contain multiple of the above epoxy resins.

[0049] The phenolic curing agent may be at least one selected from the group consisting of phenolic resins and phenolic novolac resins.

[0050] For example, the phenolic resin may be at least one selected from the group consisting of 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, and triphenylmethane-type phenolic resins. The phenolic resin may also be a copolymer composed of two or more of the above phenolic resins.

[0051] For example, the phenol novolac resin may be a resin obtained by condensing or co-condensing phenols and / or naphthols with aldehydes under an acidic catalyst. The phenols constituting the phenol novolac resin may be at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. For example, the naphthols constituting the phenol novolac resin may be at least one selected from the group consisting of α-naphthol, β-naphthol, and dihydroxynaphthalene. The aldehydes constituting the phenol novolac resin may be at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0052] For example, the coupling agent may be any coupling agent that reacts with glycidyl groups contained in resin compositions such as epoxy resins (epoxy compounds). The coupling agent improves adhesion between the magnet particles and the resin composition, thereby improving the mechanical strength of the bonded magnet. The coupling agent that reacts with glycidyl groups may be, for example, a silane-based compound (silane coupling agent). For example, the silane coupling agent may be at least one selected from the group consisting of epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, acid anhydride silane (e.g., silane with a succinic anhydride group), methacryl silane, and vinyl silane. The compound may contain one of the above coupling agents. The compound may also contain multiple of the above coupling agents.

[0053] For example, the wax may be at least one composition selected from the group consisting of synthetic wax, saturated fatty acid, saturated fatty acid salt, and saturated fatty acid ester. Adding wax to the resin composition facilitates flow of the compound during the molding process, improving the remanence of the bonded magnet. Furthermore, due to the lubricity of the wax, the magnetic particles in the compound slide easily against each other, facilitating rotation of each magnetic particle in the molding process by a magnetic field, and aligning the easy axis of magnetization of the magnetic domains in each magnetic particle along the magnetic field. In other words, each magnetic particle is oriented so that its magnetization direction is approximately parallel to the magnetic field. As a result, the remanence of the bonded magnet is improved. For example, the wax may be at least one wax selected from the group consisting of polyethylene wax, amide wax, and montan wax. Among the waxes listed above, montan wax (montan acid ester) is preferred because it lubricates the magnetic powder during the molding process, facilitating rotation of each magnetic particle in the magnetic field, and improving the orientation of the magnetic powder. The compound may contain one type of wax from the above. The compound may contain multiple types of wax from the above.

[0054] For example, the reactive diluent may be at least one of a monoepoxy compound and a diepoxy compound. The reactive diluent may be a monofunctional epoxy resin. The reactive diluent may be, for example, at least one selected from the group consisting of alkyl monoglycidyl ether, alkyl phenol monoglycidyl ether, and alkyl diglycidyl ether. Diluting the epoxy resin with a reactive diluent tends to reduce the viscosity of the resin composition. As a result, the compound flows more easily within the mold, the compound is more easily filled into the mold without gaps, the magnetic powder is more easily packed densely within the bonded magnet, and the magnetization direction of each magnetic particle is more easily aligned along the magnetic field during the molding process. As a result, the bulk density, mechanical strength, and residual magnetic flux density of the bonded magnet manufactured from the compound tend to be increased.

[0055] To improve the recyclability, moldability, and cost of the compound, the resin composition may contain a flame retardant. For example, the flame retardant may be at least one compound 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. The compound may contain one or more of the above flame retardants.

[0056] The compound may further contain another thermosetting resin in addition to the epoxy resin. For example, the compound may further contain at least one thermosetting resin selected from the group consisting of maleimide compounds, polyimides, polyamides, and polyamideimides. A part or all of the thermosetting resin in the compound may be uncured (uncured thermosetting resin). A part or all of the thermosetting resin in the compound may be semi-cured (B-stage thermosetting resin). A part of the thermosetting resin in the compound may be uncured, and the remaining part of the thermosetting resin in the compound may be semi-cured.

[0057] The resin composition may contain, in addition to the thermosetting resin, other resins such as a thermoplastic resin, etc. For example, the resin composition may further contain at least one other resin selected from the group consisting of a polyphenylene sulfide resin, an acrylic resin, a methacrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and a silicone resin.

[0058] <Magnet Powder> As described above, the magnet powder is a powder containing an Sm—Fe—N system permanent magnet (SmFeN powder). For example, the SmFeN powder contains Sm as the main phase. ２ Fe １７ N ３ For example, at least a part of the SmFeN powder may contain Th ２ An anisotropic magnet powder containing Zn-type crystals (rhombohedral crystals) as the main phase may be used. An anisotropic magnet powder is a magnet powder in which the individual magnet particles constituting the magnet powder are single crystals, or a magnet powder in which the individual magnet particles constituting the magnet powder are composed of a large number of fine single crystal grains (magnetic domains), and the magnetization easy axis of each crystal grain is aligned in a specific direction. For example, at least a portion of the SmFeN powder is TbCu ７ The compound may be an isotropic magnet powder containing a hexagonal crystal as the main phase. Isotropic magnet powder is a magnet powder in which the individual magnet particles constituting the magnet powder are composed of a large number of fine single crystal grains (magnetic domains), and the orientation of the easy axis of magnetization of each crystal grain is disordered. In addition to the magnet powder made of an Sm—Fe—N permanent magnet, the compound may further contain powder made of another permanent magnet.

[0059] The method for producing the SmFeN powder is not limited. For example, the method for producing the SmFeN powder may include a step of forming an alloy powder containing Sm and Fe by mechanical alloying, and a step of obtaining the SmFeN powder by heating the alloy powder in nitrogen gas. The SmFeN powder may also be produced by a rapid solidification method. In the rapid solidification method, a molten alloy is supplied to the surface of a rotating water-cooled roll. As a result, the molten alloy is rapidly cooled and solidified on the surface of the water-cooled roll. The solidified alloy is pulverized to obtain the SmFeN powder. Alternatively, the SmFeN powder may be produced by an HDDR (Hydrogenation Disproportion Desorption Recombination) method.

[0060] The SmFeN powder may be, for example, a non-pulverized powder (spherical magnet powder) obtained by the build-up method of Nichia Corporation. The surface of each magnet particle constituting the SmFeN powder may be coated with an inorganic film by surface treatment. For example, the inorganic film may contain a phosphate or a silica-based compound.

[0061] Average particle size or median diameter d of SmFeN powder ５０ The average particle size or median diameter d of the SmFeN powder is preferably 0.5 μm or more and 100 μm or less, more preferably 1 μm or more and 10 μm or less, and even more preferably 2 μm or more and 3 μm or less. ５０ can be measured by a laser diffraction particle size distribution analyzer.

[0062] (Method for manufacturing compound) The method for manufacturing the compound may include a step of obtaining a compound containing magnet powder and resin composition by mixing magnet powder, a resin composition, and an organic solvent. The mass of the magnet powder and the mass of each component constituting the resin composition are adjusted to match the composition of the compound described above. The organic solvent may be removed from the compound by drying, or the organic solvent may remain in the compound.

[0063] For example, a resin solution is prepared by uniformly stirring and mixing a resin composition containing at least an epoxy resin and an encapsulated curing agent in an organic solvent. In addition to the epoxy resin and encapsulated curing agent that constitute the resin composition, the resin solution may further contain one or more components selected from the group consisting of a curing accelerator, a coupling agent, a wax, a reactive diluent, and a flame retardant.

[0064] The resin solution and the magnet powder may be stirred and mixed to obtain a compound. That is, the mixture (paste) of the resin solution and the magnet powder may be used as the compound.

[0065] As described above, mixing the resin composition and organic solvent reduces the viscosity of the resin composition. This reduction in viscosity of the resin composition makes it easier for the magnet powder and resin composition to be mixed uniformly, and for the surfaces of each magnetic particle constituting the magnet powder to be coated with the resin composition. As a result, a homogeneous compound is easily formed, the electrical insulation of the compound is easily improved, and the electrical resistivity, bulk density, mechanical strength, and residual magnetic flux density of the bonded magnet formed from the compound are easily increased. Because the above-mentioned effects attributable to the organic solvent are easily obtained, the mass of the organic solvent per 1 part by mass of epoxy resin may be 5 parts by mass or more and 100 parts by mass or less.

[0066] The organic solvent is not particularly limited as long as it is a liquid that dissolves each component of the resin composition other than the capsules (capsule-type curing agent). For example, the organic solvent may be at least one solvent selected from the group consisting of acetone, N-methylpyrrolidinone (N-methyl-2-pyrrolidone), γ-butyrolactone, dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone, methyl isobutyl ketone, toluene, and xylene.

[0067] When the capsules themselves contain polyurethane, polyurethane is easily dissolved in ketone-based solvents (e.g., acetone), and therefore each capsule is easily ruptured or liquefied by the ketone-based solvent during compound production. As the capsules rupture or liquefy, the amine seeps out from the inside of the capsule to the outside, making it easier for the amine and epoxy resin in the compound to come into contact with each other. As a result, the epoxy resin and amine in the compound are more likely to react during compound production and storage. In other words, the compound is more likely to harden during compound production and storage. For these reasons, when the capsules themselves contain polyurethane and the organic solvent used in compound production is a ketone-based solvent, it is difficult to inhibit the compound's hardening during compound production and storage. If the compound hardens during compound production and storage, the compound is already hardened before the molding process for forming a molded product from the compound is initiated. As a result, the bulk density and mechanical strength of the compact formed from the compound during the molding process are difficult to increase, and the bulk density, mechanical strength, and remanence of the final bonded magnet are also difficult to increase. If the compound has already hardened before the molding process begins, it becomes difficult to produce a bonded magnet from the compound in the first place. On the other hand, polyurethane is difficult to dissolve in non-ketone solvents. Therefore, if the capsules themselves contain polyurethane, it is preferable that the organic solvent mixed with the magnetic powder and resin composition during compound production be a non-ketone solvent, as this helps to prevent the capsules from bursting and liquefying during compound production and to prevent the compound from hardening during production and storage. For example, the non-ketone solvent may be at least one selected from the group consisting of toluene, ethyl acetate, xylene, cyclohexane, mineral spirits, n-butyl acetate, and propylene glycol monomethyl ether acetate. A non-ketone solvent may also be referred to as a solvent consisting of an organic compound without a ketone group. The ketone solvent may be rephrased as a solvent made of an organic compound having a ketone group.

[0068] After stirring and mixing the resin solution and magnet powder, the organic solvent may be removed from the resin solution to obtain a powder consisting of magnet powder and a resin composition. In other words, the powder consisting of magnet powder and a resin composition may be used as a compound. A powder obtained by pulverizing a mixture (lump) consisting of magnet powder and a resin composition may be used as a compound. As the organic solvent is removed from the resin solution, the resin composition adheres to the surface of each magnet particle that constitutes the magnet powder. The resin composition may adhere to part or the entire surface of each magnet particle. The method for removing the organic solvent from the resin solution is not particularly limited. For example, the organic solvent may be removed from the resin solution by drying the mixture of the resin solution and magnet powder. For example, the method for drying the resin solution may be vacuum drying.

[0069] A compound may be obtained by further mixing the mixture of magnet powder and resin composition with wax.

[0070] The compound may be compressed to produce a tablet made of the compound. The tablet made of the compound may be used as a raw material for a bonded magnet. The size and shape of the tablet are not particularly limited. For example, the tablet may be cylindrical.

[0071] (Method for manufacturing a bonded magnet) The method for manufacturing a bonded magnet (anisotropic bonded magnet) according to this embodiment includes at least a supplying step and a molding step. The method for manufacturing a bonded magnet may further include a cooling step, a demagnetizing step, a thermal hardening step, and a magnetizing step following the supplying step and the molding step. Each step will be described in detail below.

[0072] <Feeding Step> In the feeding step, the compound is fed into the mold (cavity). The temperature of the compound itself fed into the mold may be room temperature. The compound fed into the mold may be in the form of a powder, tablet, or paste.

[0073] <Molding Process> In the molding process, the compound in the mold is compressed while a magnetic field is applied to the compound in the mold heated to molding temperature T. Each magnetic particle in the compound is magnetized and rotated by the magnetic field H, and the easy axis of magnetization of the magnetic domain in each magnetic particle is oriented along the magnetic field. In other words, each magnetic particle 3 in the compound 2 is oriented so that the magnetization direction m of each magnetic particle 3 is approximately parallel to the magnetic field H (see Figure 2). When each magnetic particle 3 is a single crystal grain (single magnetic domain), the magnetization direction m of each magnetic particle 3 is the same as the direction in which the easy axis of magnetization of each magnetic particle 3 extends. The molding temperature T may be equal to or higher than the thermal curing temperature of the resin composition 5 containing the epoxy resin and the capsule-type curing agent. The thermal curing temperature may be rephrased as the temperature at which thermal curing of the epoxy resin begins. By thermally curing the resin composition 5 in the molding process, a molded body 2A is formed that includes the magnetic powder (plurality of magnetic particles 3) oriented along the magnetic field H and a cured product of the resin composition 5 (epoxy resin). In other words, a molded body 2A is formed that is made of a cured product of the compound 2. The magnetization direction M of the entire molded body 2A becomes approximately or completely parallel to the direction of the magnetic field H applied to the compound in the molding process.

[0074] The compact 2A may be a completed anisotropic bonded magnet. The magnetization direction of the entire anisotropic bonded magnet is approximately or completely parallel to the direction of the magnetic field H applied to the compound in the molding process, the magnetization direction M of the entire compact 2A, and the magnetization direction m of each magnetic particle 3 in the bonded magnet. The anisotropic bonded magnet can have a high remanence due to the excellent orientation of the magnetic powder. Furthermore, the mechanical strength and remanence of the anisotropic bonded magnet are increased due to the compression of the compound in the molding process (i.e., the increase in the filling rate of the magnetic powder in the compact) and the thermal hardening of the compound.

[0075] For example, the molding temperature T may be 80°C or higher and 180°C or lower, preferably 120°C or higher and 150°C or lower. If the molding temperature T is within the above range, one or more capsule-type curing agents in the compound are likely to burst. If the molding temperature T is above the above lower limit, the compound according to the present embodiment is likely to cure in a shorter time than conventional compounds not containing amines or compounds containing phenolic curing agents, and the bulk density, mechanical strength, and residual magnetic flux density of the bonded magnet formed from the compound according to the present embodiment are likely to be higher than those of conventional compounds or compounds containing phenolic curing agents. If the molding temperature T exceeds the above upper limit, the compound is likely to cure too quickly during the molding process, and the time allowed for rotation and orientation of the individual magnet particles in the compound is too short. As a result, it is difficult to orient each magnetic particle in the compound so that the magnetization direction of each magnetic particle is parallel to the magnetic field, and the remanence of the bonded magnet is likely to decrease. Furthermore, if the molding temperature T exceeds the above-mentioned upper limit, the compound is likely to harden excessively quickly during the molding process, the compound is unlikely to flow within the mold (cavity), the magnetic powder in the bonded magnet is unlikely to be densely packed, and the compound is unlikely to fill the mold (cavity) without gaps. As a result, the bulk density, mechanical strength, and remanence of the bonded magnet are likely to decrease. If the molding temperature T is too high, the Sm-Fe-N permanent magnet is likely to deteriorate, and the remanence and coercivity of the bonded magnet are likely to decrease.

[0076] For example, the time (molding time t) during which the compound in the mold is heated at molding temperature T may be 0.5 minutes or more and 15 minutes or less. Molding time t may be interpreted as the time required for the compound in the mold to sufficiently (or completely) harden. When molding time t is equal to or greater than the above-mentioned lower limit, the compound according to the present embodiment hardens more easily than conventional compounds that do not contain amines or compounds that contain phenolic curing agents. Therefore, the bulk density, mechanical strength, and residual magnetic flux density of the bonded magnet formed from the compound according to the present embodiment are likely to be higher than those of conventional compounds or compounds that contain phenolic curing agents. Even when molding time t is equal to or less than the above-mentioned upper limit (i.e., even when molding time t is short), the bulk density, mechanical strength, and residual magnetic flux density of the bonded magnet formed from the compound according to the present embodiment are likely to be higher than those of conventional compounds or compounds that contain phenolic curing agents. In other words, when the molding time t is below the upper limit value, the bulk density, mechanical strength, and residual magnetic flux density of bonded magnets formed from conventional compounds or compounds containing phenolic curing agents tend to be lower than those of bonded magnets formed from the compound according to this embodiment.

[0077] For example, the pressure (molding pressure) acting on the compound in a mold heated to molding temperature T may be 500 MPa or more and 2000 MPa or less, preferably 700 MPa or more and 2000 MPa or less, and more preferably 980 MPa or more and 2000 MPa or less. Molding pressure may be rephrased as the pressure exerted by the mold on the compound in the mold. If the molding pressure is within the above range, one or more capsule-type curing agents in the compound are likely to burst.

[0078] In the molding process, application of a magnetic field to the compound in the mold may be started before the mold is heated or before the temperature of the heated mold reaches the molding temperature T. In the molding process, application of a magnetic field to the compound in the mold may be started simultaneously with compression of the compound in the mold. Application of a magnetic field to the compound in the mold may be started earlier than compression of the compound in the mold. In the molding process, application of a magnetic field to the compound in the mold may be stopped simultaneously with the molding pressure reaching a maximum value. Application of a magnetic field to the compound in the mold may be stopped simultaneously with the completion of compression of the compound in the mold.

[0079] The magnetic field applied to the compound in the mold may be a static magnetic field (a continuous, constant magnetic field). The magnetic field may also be a pulsed magnetic field (a pulsed magnetic field). For example, the strength of the static magnetic field may be 0.5 T (tesla) or more and 2.5 T or less, preferably 1.0 T or more and 2.5 T or less, and more preferably 2.0 T or more and 2.5 T or less. For example, the time for which the static magnetic field is applied to the compound in the mold may be 0.08 minutes or more and 4 minutes or less, preferably 0.5 minutes or more and 4 minutes or less, and more preferably 1 minute or more and 4 minutes or less. For example, the strength of the pulsed magnetic field may be 4 T or more and 12 T or less, or 8 T or more and 12 T or less. The pulsed magnetic field may be applied to the compound once or multiple times.

[0080] <Cooling Process> After the molding process, a cooling process may be further carried out. In the cooling process, the mold containing the green body (bonded magnet) is cooled. For example, in the cooling process, the mold containing the green body may be cooled to room temperature. For example, the method for cooling the mold containing the green body may be natural cooling. In the cooling process, it is not necessary to apply a magnetic field to the green body in the mold. However, a magnetic field may be applied to the green body in the mold in the cooling process. The green body (bonded magnet) in the mold is more likely to solidify through the cooling process. As a result, the mechanical strength of the green body in the mold is increased, and deformation and breakage of the green body in each process after the cooling process are suppressed, making it easier to increase the mechanical strength of the bonded magnet.

[0081] <Demagnetization Step> A demagnetization step may be further performed after the molding step. The demagnetization step may be performed after the cooling step. The demagnetization step may be performed simultaneously with the cooling step. In the demagnetization step, a magnetic field (reverse magnetic field) having a direction opposite to that of the magnetic field H used in the molding step is applied to the molded body, thereby demagnetizing the molded body. Demagnetizing the molded body suppresses deformation of the molded body due to the magnetic force of the molded body itself. For example, deformation of the molded body due to the magnetic force of the molded body itself is a phenomenon in which each magnetic particle located near the surface of the molded body protrudes from the surface of the molded body together with the resin composition, and one or more protrusions containing the magnetic particles and the resin composition are formed on the surface of the molded body. When the demagnetization step is performed while the molded body is housed in a mold, deformation and damage of the molded body that accompanies removal from the mold are suppressed. In other words, the molded body may be removed from the mold after the demagnetization step. After the molding step or the cooling step, the molded body removed from the mold may be demagnetized using a separate magnetic field application device. When the demagnetization step is performed, it is preferable to perform the magnetization step described below.

[0082] <Thermal curing step> After the molding step, cooling step, or demagnetizing step, a thermal curing step may be further carried out. In the thermal curing step, the molded body is heated to a temperature equal to or higher than the thermal curing temperature of the epoxy resin. As a result, the thermal curing of the epoxy resin in the molded body progresses further, and the bulk density, mechanical strength, and residual magnetic flux density of the molded body (bonded magnet) tend to be further increased.

[0083] <Magnetic Processing> After the demagnetization processing, a magnetic processing may be further performed. After the demagnetization processing and the subsequent thermal curing processing, a magnetic processing may be further performed. In the magnetic processing, a magnetic field in the same direction as the magnetic field used in the molding processing may be applied to the compact. As a result, the compact is magnetized and becomes an anisotropic bonded magnet again.

[0084] (Analysis Method) In order to analyze and identify the composition of a bonded magnet, a sample obtained by pulverizing the bonded magnet may be analyzed. In order to analyze and identify the composition of the compound itself retroactively from the bonded magnet, a sample obtained by pulverizing the bonded magnet may be analyzed. Furthermore, the sample obtained by pulverization may be dissolved in an organic solvent, and the magnetic powder that makes up the sample may be separated from the resin composition dissolved in the organic solvent. The separated resin composition and magnetic powder may each be analyzed individually. In the case where the composition of an uncured compound is analyzed and identified, the compound may also be dissolved in an organic solvent, and the magnetic powder may be separated from the resin composition dissolved in the organic solvent. The separated resin composition and magnetic powder may each be analyzed individually. For example, each component constituting the resin composition (such as the epoxy resin and the encapsulated curing agent) may be analyzed and identified by one or more analytical methods selected from the group consisting of infrared spectroscopy (IR), nuclear magnetic resonance (NMR), mass spectrometry (MS), gas chromatography (GC), and high performance liquid chromatography (HPLC). For example, the magnet powder may be analyzed and characterized by one or more analytical methods selected from the group consisting of X-ray fluorescence analysis (XRF), inductively coupled plasma (ICP) emission spectroscopy, photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS or EDX), and mass spectroscopy. The remanence Br1 of the bonded magnet and the remanence Br2 of the magnet powder itself may satisfy the following formula 1: Br1 = Br2 × (V2 / V1) × D (1) V1 in formula 1 is the volume of the entire bonded magnet. V2 in Equation 1 is the volume of the magnetic powder itself contained in the bonded magnet.V2 / V1 corresponds to the filling rate of the magnetic powder in the bonded magnet. D in Equation 1 is the degree of orientation of the magnetic powder in the bonded magnet. Based on Equation 1 above, the degree of orientation D is expressed as Br1 / {Br2 x (V2 / V1)}. In other words, the degree of orientation D can be determined based on measurements of Br1, Br2, V1, and V2. A high degree of orientation means that the easy axis of magnetization in each magnetic particle that makes up the magnetic powder contained in the bonded magnet is aligned. In other words, a high degree of orientation means that the magnetization direction of each magnetic particle that makes up the magnetic powder contained in the bonded magnet is aligned. For example, the degree of orientation D (unit: %) of the magnetic powder in the bonded magnet may be 80% or more and 100% or less.

[0085] The present invention is not necessarily limited to the above-described embodiments. Various modifications of the present invention are possible without departing from the spirit of the present invention, and these modifications are also included in the present invention.

[0086] The present invention will be described in detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

[0087] [Capsule-type curing agent] In the following Examples 1 to 5, HX-3088 was used as the capsule-type curing agent contained in the compound. ＴＭ , HXA3792 ＴＭ , HX-3721 ＴＭ , HX-3748 ＴＭ , and HX-3742 ＴＭ Any one selected from the group consisting of: HX-3088 ＴＭ , HXA3792 ＴＭ , HX-3721 ＴＭ , HX-3748 ＴＭ , and HX-3742 ＴＭ Both of these are Novacure products manufactured by Asahi Kasei Corporation. ＴＭ All of the five capsule-type curing agents mentioned above contained a large number of capsules formed from polyurethane and an amine encapsulated in each of the capsules. Of the five capsule-type curing agents mentioned above, HX-3721 ＴＭ The capsule thickness of HX-3748 was the smallest. ＴＭThe thickness of the capsule is HX-3721 ＴＭ The thickness of the capsule was larger than that of HX-3088. ＴＭ , HXA3792 ＴＭ , and HX-3742 ＴＭ The thickness of each capsule is HX-3748 ＴＭ It was larger than the thickness of the capsule.

[0088] Example 1 An epoxy resin, a curing agent, a coupling agent, and an organic solvent were mixed to produce a solution of the resin composition (resin solution) of Example 1. The epoxy resin was a biphenyl-type epoxy resin (YX-4000H manufactured by Mitsubishi Chemical Corporation). ＴＭ ) was used. The mass of the epoxy resin was 3.5 g. The curing agent used was the above-mentioned HX-3088 (encapsulated curing agent). The relative mass of the encapsulated curing agent to 100 parts by mass of the epoxy resin was 14 parts by mass. The coupling agent used was N-phenyl-3-aminopropyltrimethoxysilane (KBM-573 manufactured by Shin-Etsu Chemical Co., Ltd.). ＴＭ ) was used. The mass of the coupling agent was 0.6 g. A mixture of toluene and ethyl acetate was used as the organic solvent. Both toluene and ethyl acetate are non-ketone solvents. The relative mass of the organic solvent to 1 part by mass of the epoxy resin was 50 parts by mass. In Table 1 below, toluene and ethyl acetate are referred to as "non-ketone."

[0089] The resin solution and the magnet powder were stirred and mixed. The mixture of the resin solution and the magnet powder was heated (dried) to remove the organic solvent, and the surface of each magnet particle constituting the magnet powder was covered with the resin composition. ２ Fe １７ N ３ The mass of the magnetic powder was 100 g.

[0090] Through the above steps, a powder (compound of Example 1) consisting of magnet powder and resin composition was produced.

[0091] An anisotropic bonded magnet was produced from the compound of Example 1 by the following method. The compound used to produce the anisotropic bonded magnet was different from the compound used in the storage test and differential scanning calorimetry (DSC) described below. In other words, the compound immediately after production was used to produce the anisotropic bonded magnet without being used in the storage test or DSC.

[0092] In the feeding step, approximately 2 g of compound was fed into the mold of the molding device. The shape of the mold (cavity) was cubic, and the capacity of the mold (cavity) was 7 mm x 7 mm x 7 mm. The molding device (hydraulic press) was TM-MPH10525-10A2TM manufactured by Tamagawa Seisakusho Co., Ltd. ＴＭ was used.

[0093] In the molding process, the compound in the mold was compressed while a static magnetic field was applied to the compound in the mold heated to molding temperature T. The molding temperature T was 150°C. The time during which the compound in the mold was heated to molding temperature T (molding time) was 10 minutes. The strength of the static magnetic field was maintained at 2.5 T. The pressure acting on the compound in the mold heated to molding temperature T (molding pressure) was maintained at 1800 MPa. A bonded magnet was formed from the compound through the above molding process. The dimensions of the bonded magnet were 7 mm length x 7 mm width x 7 mm height. In other words, the bonded magnet was cubic.

[0094] In the cooling step following the molding step, the mold containing the bonded magnet was cooled to room temperature by natural cooling. After the cooling step, the bonded magnet was removed from the mold.

[0095] (Examples 2 to 5, Comparative Examples 1 to 3) The curing agent in Example 2 was the above-mentioned HXA3792. ＴＭ The curing agent used in Example 3 was the above-mentioned HX-3721 (encapsulated curing agent). ＴＭ The curing agent used in Example 4 was the above-mentioned HX-3748 (encapsulated curing agent). ＴＭ The curing agent used in Example 5 was the above-mentioned HX-3742 (encapsulated curing agent).ＴＭ (encapsulated hardener) was used.

[0096] No capsule-type curing agent was used as a raw material for the compounds of Comparative Examples 1 to 3. In the production of the compounds of Comparative Examples 1 to 3, acetone (a ketone-based solvent) was used as the organic solvent instead of a non-ketone-based solvent.

[0097] The curing agent in Comparative Example 1 was 2-ethyl-4-methylimidazole (2E4MZ manufactured by Shikoku Chemical Industry Co., Ltd.). ＴＭ ) was used. 2-Ethyl-4-methylimidazole is a type of amine. The relative mass of 2-ethyl-4-methylimidazole to 100 parts by mass of epoxy resin was 2 parts by mass.

[0098] The curing agent in Comparative Example 2 was 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Chemical Industry Co., Ltd.). ＴＭ ) was used. 2-phenyl-4-methylimidazole is a type of amine. The relative mass of 2-phenyl-4-methylimidazole to 100 parts by mass of epoxy resin was 2 parts by mass.

[0099] The curing agent in Comparative Example 3 was a phenolic curing agent and 2-ethyl-4-methylimidazole (2E4MZ ＴＭ In Table 1 below, the phenolic curing agent is indicated as "Ph." The phenolic curing agent was a phenol novolak resin (HP-850N manufactured by Resonac Corporation). ＴＭ The relative mass of the phenolic curing agent to 100 parts by mass of the epoxy resin was 56 parts by mass. The relative mass of the 2-ethyl-4-methylimidazole to 100 parts by mass of the epoxy resin was 2 parts by mass.

[0100] With the exception of the above-mentioned items, the compounds of Examples 1 to 5 and Comparative Examples 1 to 3 were produced in the same manner as Example 1. Furthermore, with the exception of the above-mentioned items, the bonded magnets of Examples 1 to 5 and Comparative Example 3 were produced in the same manner as Example 1. As will be described later, the compounds of Comparative Examples 1 and 2 were clearly inferior to Examples 1 to 5 in that they tended to harden during storage. Therefore, it was difficult to produce bonded magnets from the compounds of Comparative Examples 1 and 2.

[0101] <Storage Test> The compounds of Examples 1 to 5 and Comparative Examples 1 to 3 were stored in the atmosphere. The temperature of each compound during storage was maintained at room temperature. The compounds of Examples 1 to 5 had not hardened after one month of storage and were in a state where they could be used as raw materials for bonded magnets. In other words, the pot life of each compound of Examples 1 to 5 was at least one month. On the other hand, the compounds of Comparative Examples 1 to 3 had already hardened after one week of storage and could no longer be used as raw materials for bonded magnets. In other words, the pot life of each compound of Comparative Examples 1 to 3 was less than one week.

[0102] <Differential Scanning Calorimetry (DSC)> Differential scanning calorimetry curve A (DSC curve A) and differential scanning calorimetry curve B (DSC curve B) were measured by the following method for each compound of Examples 1 to 5. The compounds used to measure each DSC curve were immediately after production and had not undergone the above storage test.

[0103] Each DSC curve was measured during the temperature rise process of the compound. In measuring each DSC curve, each compound was gradually heated from room temperature to 280°C. The horizontal axis of each DSC curve indicates the temperature of the compound (unit: °C). The vertical axis of the DSC curve indicates the heat flow (unit: mW) at each temperature. A positive heat flow (a positive peak in the DSC curve) indicates the heat generation of the compound. A negative heat flow (a negative peak in the DSC curve) indicates the heat absorption of the compound.

[0104] Before measuring DSC curve A, each compound was pressurized at 1000 MPa and further heated at 150°C. In any of the DSC curves A of Examples 1 to 5, no positive peak indicating heat generation associated with curing of the epoxy resin was detected. Therefore, the compounds (epoxy resins) of Examples 1 to 5 had already cured before measuring DSC curve A. In other words, the capsule-type curing agents in the compounds of Examples 1 to 5 had already ruptured due to the pressurization before measuring DSC curve A.

[0105] Before measuring DSC curve B, each compound was heated at 150°C without pressure. In all of the DSC curves B of Examples 1 to 5, a positive peak was detected near 180°C. Therefore, each compound of Examples 1 to 5 was not cured before measuring DSC curve B, and curing of each compound (epoxy resin) began during the measurement of DSC curve B. In other words, the capsule-type curing agent in each compound of Examples 1 to 5 burst due to heating (thermal expansion of the amine inside the capsule) during the measurement of DSC curve B.

[0106] The above-described differential scanning calorimetry measurements demonstrated that the capsule-type curing agents in the compounds of Examples 1 to 5 burst when pressurized or heated. Since the compounds of Comparative Examples 1 to 3 began to harden immediately after production, it was not possible to measure DSC curve A and DSC curve B for the compounds of Comparative Examples 1 to 3.

[0107] <Measurement of bulk density> The mass of each bonded magnet was measured using an electronic balance. The volume of each bonded magnet was calculated from the dimensions of the bonded magnet. The bulk density (unit: g / cm) of each bonded magnet was calculated by dividing the mass of each bonded magnet by the volume of each bonded magnet. ３ The bulk density of each of the bonded magnets of Examples 1 to 5 and Comparative Example 3 is shown in Table 1 below.

[0108] <Measurement of Residual Magnetic Flux Density> The residual magnetic flux density Br (unit: tesla) of each bonded magnet was measured. A high-sensitivity normal conducting magnet type (electromagnet type) vibrating sample magnetometer (VSM) was used to measure Br. The vibrating sample magnetometer was manufactured by Tamagawa Seisakusho Co., Ltd. The residual magnetic flux density Br of each of the bonded magnets in Examples 1 to 5 and Comparative Example 3 is shown in Table 1 below.

[0109]

[0110] For example, the compound according to one aspect of the present invention may be used as a raw material for a bonded magnet.

[0111] 2...Compound, 2A...Molded body (bonded magnet), 3...Magnetic particles (magnet powder), 5...Resin composition (epoxy resin), 6...Amine, 7...Capsule, H...Magnetic field, m...Magnetization direction of magnetic particles, M...Magnetization direction of bonded magnet.

Claims

1. A compound comprising a magnet powder and a resin composition, wherein the magnet powder is an alloy containing samarium, iron, and nitrogen, and the resin composition comprises an epoxy resin and one or more capsules containing an amine.

2. The compound according to claim 1, wherein the amine comprises at least one selected from imidazoles.

3. The compound of claim 1, wherein the amine is at least one selected from the group consisting of 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 1-aminopropyl-2-methylimidazole.

4. The compound of claim 1, wherein said one or more capsules comprise polyurethane.

5. The compound of claim 1, wherein the one or more capsules comprise a polyurethane formed from one or more isocyanates selected from the group consisting of tolylene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene phenylene polyisocyanate, n-octadecyl isocyanate, 1,6-hexamethylene diisocyanate, cyclohexyl isocyanate, n-dodecyl isocyanate, and n-hexadecyl isocyanate.

6. The compound according to claim 1, wherein the epoxy resin is at least one selected from the group consisting of biphenyl-type epoxy resins, dicyclopentadiene-type epoxy resins, naphthalene-type epoxy resins, and cresol novolac-type epoxy resins.

7. The compound according to claim 1, which does not contain a phenolic curing agent.

8. The compound according to claim 7, wherein the phenolic curing agent is at least one selected from the group consisting of phenolic resins and phenolic novolac resins.

9. The compound according to claim 1, which is a powder, tablet or paste.

10. The compound according to any one of claims 1 to 9, which is a raw material for a bonded magnet.

11. The compound according to any one of claims 1 to 9, which is a raw material for an anisotropic bonded magnet in which the magnetization direction of each of the multiple magnetic particles that make up the magnetic powder is aligned.

Images