JP6608643B2 - Resin compound for Nd-Fe-B based bonded magnet, Nd-Fe-B based bonded magnet and method for producing the same - Google Patents

Description

  The present invention relates to a resin compound for an Nd—Fe—B based bonded magnet, an Nd—Fe—B based bonded magnet using the same, and a method for producing the same.

The rare earth bonded magnet refers to a magnet prepared by mixing rare earth magnetic powder such as neodymium (Nd) and samarium (Sm) and a binder (binder material) such as a resin composition and molding the mixture into a predetermined shape. . Among them, the Nd—Fe—B based bonded magnet is excellent in magnet characteristics and is a typical rare earth bonded magnet.
Rare earth bonded magnets have a greater (higher) shape freedom than sintered ferrite magnets, are easy to form in various shapes such as thin ring shapes, have high dimensional accuracy, and have excellent mechanical properties. There is a feature that chipping is difficult to occur. Therefore, rare earth bonded magnets are widely used in automobiles, general household appliances, communication / acoustic equipment, medical equipment, general industrial equipment, and the like.

  A rare earth bonded magnet is manufactured by compression molding a composite powder obtained by mixing a binder material such as a resin composition, which is called “compound”, and rare earth magnetic powder. The particle size of the magnetic powder used for the compound is adjusted to increase the packing density.

  The technical problem of rare earth bonded magnets used for applications requiring heat resistance, particularly Nd-Fe-B based bonded magnets, is that the binder material is softened when used in a high temperature environment, whereby Nd-Fe-B based bonded magnets are used. That is, the mechanical strength of the steel is significantly reduced. In order to solve such technical problems, for example, binder materials described in Patent Documents 1 to 3 are known as conventional techniques. In patent document 1, what contains an epoxy resin and polybenzimidazole by a fixed ratio is used as a binder material. Thereby, the mechanical strength of the rare earth bonded magnet at a high temperature can be improved. In Patent Document 2, a dihydrobenzoxazine compound and a mixture of a dihydrobenzoxazine compound and an epoxy resin or a phenol resin are used as a binder material. Thereby, the mechanical strength of the rare earth bonded magnet at a high temperature can be improved. Further, in Patent Document 3, polyamideimide is used as a binder material. Thereby, the mechanical strength of the rare earth bonded magnet at high temperature can be improved.

JP-A-8-273916 JP 2001-214054 A JP 2004-31786 A

  The inventors have studied various binder materials described in Patent Documents 1 to 3 for Nd-Fe-B bond magnets, but the studied binder materials are inferior in storage stability. No binder material satisfying both the mechanical strength at high temperature and the storage stability was found from among the binder materials described in 1).

Generally, in an epoxy resin curing system using a thermosetting curing agent, the curing reaction rarely proceeds relatively easily (for example, when an aromatic polyamine is selected), and in most cases, In order to increase the hardness and strength of the resin composition by increasing the speed of the curing reaction, a curing accelerator is used in combination. As a result of investigations by the inventors, it has been found that the curing characteristics required for Nd-Fe-B based magnet bonded magnets with phosphorus-based catalysts such as amines and triphenylphosphine, and general curing accelerators such as sulfonium salts. Even if it can be satisfied, it has been found that the pot life (long-term storage stability) of the resin composition in the compound is insufficient. In particular, when a compound stored in a high temperature and high humidity environment is used, the flowability of the powder decreases due to blocking between the compound particles in which the compound adheres to the surface of the Nd-Fe-B magnetic powder particles. It has been found that molding failure occurs, and the desired curing characteristics of the resin composition and the desired mechanical strength of the bonded magnet cannot be obtained.
Therefore, the present invention provides an Nd-Fe-B bond magnet resin compound having good storage stability in a high temperature and high humidity environment, and an Nd-Fe-B system produced using the bond magnet resin compound. An object of the present invention is to provide a bonded magnet and a manufacturing method thereof.

As a result of intensive studies, the inventors of the present invention obtained a resin composition comprising an epoxy resin (A), a curing agent (B) and a curing accelerator (C), and a bonded magnet powder (D). In the resin compound for Nd-Fe-B bond magnets contained, the storage stability of the resin compound for bond magnets in a high-temperature and high-humidity environment is dramatically improved by using a predetermined curing accelerator. The present invention has been completed. That is, the present invention is as follows.
[1] A resin composition comprising an epoxy resin (A), a curing agent (B), and a curing accelerator (C), and an Nd—Fe—B based magnetic powder (D) for bonded magnets, A resin compound for Nd—Fe—B based bonded magnets, wherein the accelerator (C) is at least one of borate and borane compounds.
[2] The resin compound for Nd—Fe—B bond magnets according to [1], wherein the borate of the curing accelerator (C) is a borate represented by the following general formula (1).
X ⁺ B ⁻ (R) ₄ (1)
(In the formula (1), B represents boron, X represents at least one of alkylphosphonium salt, arylphosphonium salt, imidazole or imidazole derivative salt, tertiary amine salt and quaternary ammonium salt, and R represents an alkyl group. , One selected from the group consisting of an aryl group and a fluoro group.)
[3] The resin compound for an Nd—Fe—B bond magnet according to [1], wherein the borane compound of the curing accelerator (C) is a borane compound represented by the following general formula (2).
Y ・ B (R) ₃ (2)
(In the formula (2), B represents boron, Y represents at least one of an alkyl phosphine, aryl phosphine, imidazole or imidazole derivative and tertiary amine, and R represents a group consisting of an alkyl group, an aryl group and a fluoro group. Indicates one type to be selected.)
[4] The content of the curing accelerator (C) is 0.000001 parts by mass or more and 0.6 parts by mass or less with respect to 100 parts by mass of the Nd—Fe—B based magnetic powder (D) for bonded magnets. The resin compound for Nd—Fe—B based bond magnets according to any one of [1] to [3].
[5] In any one of the above [1] to [4], the epoxy resin is at least one selected from the group consisting of a phenol novolac epoxy resin, a cresol novolac epoxy resin, and a naphthol novolac epoxy resin. The resin compound for Nd-Fe-B type bonded magnets as described.
[6] The resin compound for an Nd—Fe—B based bonded magnet according to any one of the above [1] to [4], wherein the epoxy resin has a salicylaldehyde novolak structure.
[7] The curing agent (B) is a phenol resin, and the ratio of the active group in the curing agent (B) that reacts with the epoxy group of the epoxy resin (A) to 1 equivalent of the epoxy group of the epoxy resin (A) is 0.00. 5. The resin compound for Nd—Fe—B based bond magnet according to any one of [1] to [6], which is 5 or more and 1.5 or less.
[8] An Nd—Fe—B bond magnet using the Nd—Fe—B bond magnet resin compound according to any one of [1] to [7].
[9] First step of preparing a resin composition by mixing an epoxy resin (A), a curing agent (B), and a curing accelerator (C) dissolved in a solvent, Nd—Fe—B magnetism for bonded magnets A second step of mixing the powder (D) with the resin composition and drying to produce a resin compound for an Nd-Fe-B bond magnet, compression molding the resin compound for an Nd-Fe-B bond magnet, An Nd—Fe—B based bond comprising a third step of producing a compression molded body and a fourth step of heat treating the compression molded body, wherein the curing accelerator (C) is at least one of a borate and a borane compound Magnet manufacturing method.

  According to the present invention, a Nd—Fe—B based bonded magnet resin compound having good storage stability in a high temperature and high humidity environment, and the Nd—Fe—B based bonded magnet resin compound produced using the Nd—Fe—B based bonded magnet resin compound. It is possible to provide a —Fe—B based bonded magnet and a method for producing the Nd—Fe—B based bonded magnet.

The resin compound for Nd-Fe-B bond magnets of the present invention comprises a resin composition comprising an epoxy resin (A), a curing agent (B) and a curing accelerator (C), and Nd-Fe for bonded magnets. -B type | system | group magnetic powder (D), and a hardening accelerator (C) is at least 1 sort (s) of a borate and a borane compound.
Hereinafter, the components of the Nd—Fe—B bonded magnet compound of the present invention, the manufacturing method, and the necessary items as the Nd—Fe—B bonded magnet will be described in order.

[Resin composition]
As described above, the resin composition used for the resin compound for Nd-Fe-B bond magnets of the present invention is obtained by blending an epoxy resin (A), a curing agent (B), and a curing accelerator (C). It is. The resin composition functions as a binder material that binds the Nd—Fe—B based magnetic powder (D) for bonded magnets constituting the Nd—Fe—B based bonded magnet, and serves as a source of mechanical strength. The surface of the Nd—Fe—B based magnetic powder (D) for bonded magnet is coated with the resin composition by mixing the resin composition and the Nd—Fe—B based magnetic powder (D) for bonded magnet. In addition, the resin composition may coat | cover the whole surface of Nd-Fe-B type magnetic powder (D) for bonded magnets, or may partially cover the surface of Nd-Fe-B type magnetic powder (D) for bonded magnets. May be coated. The resin composition covering the surface of the Nd—Fe—B based magnetic powder (D) for the bonded magnet is obtained when the resin compound for the Nd—Fe—B based bonded magnet is compression molded in a mold. The gap between the Nd—Fe—B magnetic powder (D) for use is filled, and the magnetic powders are bound together. And a resin composition produces the firm coupling | bonding between Nd-Fe-B type magnetic powder (D) for bond magnets through the subsequent heating process.

(Epoxy resin (A))
The epoxy resin (A) used for the resin composition of the resin compound for Nd-Fe-B bond magnets of the present invention is not particularly limited as long as it is an epoxy resin having two or more epoxy groups in one molecule. Specific examples of the epoxy resin (A) include, for example, a biphenyl type epoxy resin, a stilbene type epoxy resin, a diphenylmethane type epoxy resin, a sulfur atom-containing type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, and a naphthol novolak type. Novolak type epoxy resins such as epoxy resins, dicyclopentadiene type epoxy resins, salicylaldehyde novolac type epoxy resins and other salicylaldehyde type epoxy resins, epoxides of aralkyl type phenol resins, copolymerized epoxy resins of naphthols and phenols, Bisphenol type epoxy resin, glycidyl ether type epoxy resin of alcohol, glycidyl ether type epoxy of paraxylylene and / or metaxylylene modified phenolic resin Glycidyl ether type epoxy resin of fat, terpene modified phenol resin, cyclopentadiene type epoxy resin, glycidyl ether type epoxy resin of polycyclic aromatic ring modified phenol resin, glycidyl ether type epoxy resin of naphthidene ring-containing phenol resin, glycidyl ester type epoxy resin , Glycidyl type or methyl glycidyl type epoxy resin, alicyclic epoxy resin, halogenated phenol novolac type epoxy resin, hydroquinone type epoxy resin, trimethylolpropane type epoxy resin and olefin bond by oxidizing with peracid such as peracetic acid. Examples thereof include linear aliphatic epoxy resins obtained. These may be used alone or in combination of two or more.

  The epoxy resin (A) is preferably a biphenyl type epoxy resin from the viewpoint of water resistance, solvent resistance and oil resistance. Examples of commercially available biphenyl type epoxy resins include YX-4000, YX-4000H, YL-6121H, and YX7399 manufactured by Japan Epoxy Resin Co., Ltd.

  The epoxy resin (A) is preferably at least one selected from the group consisting of a phenol novolac epoxy resin, a cresol novolac epoxy resin, and a naphthol novolac epoxy resin from the viewpoint of high temperature mechanical strength. Among these epoxy resins (A), commercially available products include, for example, ESCN-190, ESCN-195 manufactured by Sumitomo Chemical Co., Ltd., and phenol novolac epoxy resin (N-- manufactured by DIC Corporation). 730A, N-740, N-770, N-775, N-740-80M, N-770-70M, N-865, N-865-80M), a phenol novolac type epoxy resin manufactured by Mitsubishi Chemical Corporation ( 152, 154, 157S70), cresol novolac type epoxy resin (N-660, N-665, N-670, N-673, N-680, N-690, N-695, N-665-EXP, N-672) -EXP, N-655-EXP-S, N-662-EXP-S, N-665-EXP-S, N-670-EXP-S, N-685-EXP-S, N 673-80M, N-680-75M, N-690-75M), and the like. These may be used alone or in combination of two or more.

  As one of the necessary characteristics of the Nd—Fe—B based bond magnet resin compound, there is good flowability of the Nd—Fe—B based bond magnet resin compound (powder). The epoxy resin (A) is preferably a salicylaldehyde novolak type epoxy resin from the viewpoint of achieving both good flowability and excellent curing characteristics of the Nd-Fe-B based bond magnet resin compound. The salicylaldehyde novolac type epoxy resin is, for example, an epoxy resin represented by the following general formula (3). Examples of commercially available epoxy resins represented by the following general formula (3) include, for example, “EPPN-5001H” (epoxy equivalent: 162 g / eq. Or more, 172 g, manufactured by Nippon Kayaku Co., Ltd.). / eq., softening point 51 ° C. or more and 57 ° C. or less), EPPN-501HY (epoxy equivalent 163 g / eq. or more and 175 g / eq., softening point 57 ° C. or more and 63 ° C. or less), EPPN-502H (epoxy equivalent) 158 g / eq. Or more and 178 g / eq. Or less, softening point 60 ° C. or more and 72 ° C. or less), EPPN-503 (epoxy equivalent 170 g / eq. Or more and 190 g / eq. Or less, softening point 80 ° C. or more and 100 ° C. or less) Examples thereof include 1032H60 manufactured by Mitsubishi Chemical Corporation.

（式（３）中、Ｒ¹及びＲ^２は、それぞれ独立して、炭素数１以上１８以下の１価の有機基を示し、それぞれ全てが同一でも異なっていてもよく、ｉは０以上３以下の整数、ｋは０以上４以下の整数、ｎは０以上２０以下の整数、小数又は帯小数を示し、ｉ及びｋはそれぞれ全て同一でも異なっていてもよい。）

(In Formula (3), R ¹ and R ² each independently represent a monovalent organic group having 1 to 18 carbon atoms, and each may be the same or different, and i is 0 to 3 The following integers, k is an integer of 0 or more and 4 or less, n is an integer of 0 or more and 20 or less, a decimal number or a band decimal number, and i and k may be all the same or different.

(Curing agent (B))
From the viewpoint of heat resistance, the curing agent (B) used for the resin composition of the resin compound for Nd—Fe—B bond magnets of the present invention is preferably a phenol resin. The curing agent (B) is a type that cures at low temperatures to room temperature such as aliphatic polyamines, polyaminoamides, and polymercaptan, and aromatic polyamines, acid anhydrides, phenol novolac resins, and dicyandiamide (DICY). It is classified as a heat-curing type that does not cure. In general, an epoxy resin cured with a low-temperature to room-temperature curing type curing agent has a low glass transition point and becomes a soft cured product, which is not preferable for the use of the present invention. Therefore, the curing agent (B) is preferably a heat curing type curing agent, and more preferably a phenol novolac resin. By using a phenol novolac resin as the curing agent (B), a cured resin product having a high glass transition point can be obtained, so that an Nd—Fe—B based bonded magnet having excellent heat resistance and mechanical strength can be produced.

  Examples of the phenol resin curing agent include a compound having two phenolic hydroxyl groups in one molecule, an aralkyl type phenol resin, a dicyclopentadiene type phenol resin, a salicylaldehyde type phenol resin, a novolac type phenol resin, and a benzaldehyde type phenol. Copolymerized phenol resin with aralkyl type phenol, paraxylylene and / or metaxylylene modified phenol resin, melamine modified phenol resin, terpene modified phenol resin, dicyclopentadiene type naphthol resin, cyclopentadiene modified phenol resin, polycyclic aromatic ring modified phenol resin , Biphenyl type phenol resin, triphenylmethane type phenol resin, and phenol resin obtained by copolymerizing two or more of these. These may be used alone or in combination of two or more. Examples of the compound having two phenolic hydroxyl groups in one molecule include resorcin, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenol.

  Examples of the phenol novolak resin include phenols such as phenol, cresol, xylenol, resorcin, catechol, bisphenol A, bisphenol F, phenylphenol and aminophenol, and / or naphthols such as α-naphthol, β-naphthol and dihydroxynaphthalene. And those obtained by condensation or cocondensation of aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and salicylaldehyde with an acidic catalyst. Examples of commercially available phenol novolac resins include Tamanol 758 and 759 manufactured by Arakawa Chemical Co., Ltd., and HP-850N manufactured by Hitachi Chemical Co., Ltd. These may be used alone or in combination of two or more.

  In the resin composition of the resin compound for Nd-Fe-B bond magnet of the present invention, the active group in the curing agent (B) that reacts with the epoxy group with respect to 1 equivalent of the epoxy group in the epoxy resin (A). The ratio of (for example, phenolic hydroxyl group) is preferably 0.5 or more and 1.5 or less, more preferably 0.7 or more and 1.0 or less. When the ratio of the active groups is 0.5 or more and 1.5 or less, the curing rate of the resin composition is increased, the glass transition temperature of the obtained cured product is increased, or a sufficient elastic modulus is obtained. It can suppress that the intensity | strength of the resin molded product after hardening falls.

(Curing accelerator (C))
The curing accelerator (C) used in the resin composition of the resin compound for Nd-Fe-B bond magnets of the present invention is at least one of borate and borane compounds. Thereby, the resin compound for bond magnets with favorable storage stability in a high-temperature, high-humidity environment can be obtained. Here, the high temperature and high humidity environment is, for example, an environment where the temperature is 40 ° C. and the relative humidity is 90%. The curing accelerator (C) may be a borate and a borane compound, and the curing accelerator (C) may be a borate or a borane compound.

From the viewpoint of better storage stability in a high temperature and high humidity environment, the curing accelerator (C) borate used in the resin composition of the resin compound for Nd—Fe—B based bond magnet of the present invention is preferably It is a borate represented by the following general formula (1).
X ⁺ B ⁻ (R) ₄ (1)
(In the formula (1), B represents boron, X represents at least one of alkylphosphonium salt, arylphosphonium salt, imidazole or imidazole derivative salt, tertiary amine salt and quaternary ammonium salt, and R represents an alkyl group. , One selected from the group consisting of an aryl group and a fluoro group.)

  By using the borate of the general formula (1) as the curing accelerator (C), the mechanical strength of the Nd—Fe—B based bonded magnet is further improved and the Nd—Fe—B based bonded magnet of the present invention is used. The storage stability of the resin compound in a high temperature and high humidity environment is further improved.

  In general, when an imidazole-based curing accelerator is used, an epoxy resin alone tends to cause a curing reaction. In addition, when a phosphine-based curing accelerator is used, although the epoxy resin is not cured alone, the catalytic activity may be reduced or deactivated before the Claisen rearrangement reaction proceeds due to the reaction between the epoxy resin and the phosphine. is there. In contrast, the borate used as the curing accelerator (C) of the present invention has low catalytic activity for single curing of the epoxy resin and does not lose catalytic activity until around 200 ° C. where the Claisen rearrangement reaction proceeds. For this reason, the borate represented with the said General formula (1) can be used conveniently as a hardening accelerator (C).

The alkylphosphonium salt of X in the general formula (1) is preferably a phosphonium salt having 3 or 4 alkyl groups. Each alkyl group is independently preferably an alkyl group of _C 2 _{-C 20,} more preferably an alkyl group of _C 4 _{-C 16.} The arylphosphonium salt is preferably a phosphonium salt having 3 or 4 phenyl groups which may be substituted.

The alkyl group of R in the above general formula (1) is preferably a C _{2 to} C ₂₀ alkyl group, and more preferably a C _{4 to} C ₁₆ alkyl group. The aryl group of R in the general formula (1) is preferably a phenyl group which may be substituted.

  Specific examples of the borate represented by the general formula (1) used as the curing accelerator (C) in which X is an alkylphosphonium salt or an arylphosphonium salt include, for example, tetraphenylphosphonium tetra-p-tolylborate. , Tetra-n-butylphosphonium tetrafluoroborate, n-hexadodecyltri-n-butylphosphonium tetrafluoroborate, tetraphenylphosphonium tetrafluoroborate, tetra-n-butylphosphonium tetraphenylborate, tetraphenylphosphonium tetraphenylborate, tetra Phenylphosphonium tetra-4-methylphenylborate, tetraphenylphosphonium tetra-4-fluorophenylborate, tri-tert-butylphosphonium tetraphenyl Rate and tri -tert- butyl phosphonium tetrafluoroborate, and the like. These may be used alone or in admixture of two or more. However, some of these borates are excellent in storage stability but poor in solubility in the resin, and for example, some borates need to be used after reacting in advance with a curing agent (B) or the like. Some of these borates generate benzene gas by thermal decomposition when heated to 200 ° C. or higher. From the viewpoints of environment and solubility, the borate represented by the general formula (1) used as the curing accelerator (C) is preferably tetraphenylphosphonium tetra-p-tolylborate or tetra-n-butylphosphonium tetraphenylborate. And at least one selected from the group consisting of tetraphenylphosphonium tetraphenylborate and tri-tert-butylphosphonium tetrafluoroborate.

  As specific examples of the borate represented by the general formula (1) used as the curing accelerator (C), X is a salt of an imidazole or an imidazole derivative, a tertiary amine salt, or a quaternary ammonium salt. (A) 2-ethyl-4-methyl-imidazole tetraphenylborate, (b) 1,8-diazabicyclo [5.4.0] undecene-7-tetraphenylborate, (c) 1,5-diazabicyclo [4. 3.0] Nonene-5-tetraphenylborate, (d) tetrabutylammonium tetraphenylborate and the like. In addition to exhibiting a curing accelerating action equivalent to that of the tetraphenylphosphonium tetraphenylborate, X is an imidazole or imidazole derivative salt, a tertiary amine salt, or a quaternary ammonium salt. The borate represented by the general formula (1) used as a curing accelerator (C) in which X is a salt of imidazole or an imidazole derivative, a tertiary amine salt, or a quaternary ammonium salt is preferable from the viewpoint of particularly excellent properties. Is at least one selected from the group consisting of (c) 1,5-diazabicyclo [4.3.0] nonene-5-tetraphenylborate and (d) tetrabutylammonium tetraphenylborate.

なお、上記式（ａ）の「Ｍｅ−」はメチル基を示し、「Ｅｔ−」はエチル基を示し、上記式（ｄ）の「Ｂｕ−」はブチル基（ＣＨ_３（ＣＨ_２）_３−）を示す。

In the above formula (a), “Me-” represents a methyl group, “Et—” represents an ethyl group, and “Bu—” in the above formula (d) represents a butyl group (CH ₃ (CH ₂ ) ₃ — ).

Further, from the viewpoint of better storage stability in a high temperature and high humidity environment, the curing accelerator (C) borane used in the resin composition of the resin compound for Nd-Fe-B rare earth bonded magnets of the present invention. The compound is preferably a borane compound represented by the following general formula (2).
Y ・ B (R) ₃ (2)
(In the formula (2), B represents boron, Y represents at least one of an alkyl phosphine, aryl phosphine, imidazole or imidazole derivative and tertiary amine, and R represents a group consisting of an alkyl group, an aryl group and a fluoro group. Indicates one type to be selected.)

The alkylphosphine of Y in the general formula (2) is preferably a phosphine having three alkyl groups. Each alkyl group is independently preferably an alkyl group of _C 2 _{-C 20,} more preferably an alkyl group of _C 4 _{-C 16.} The aryl phosphine is preferably a phosphine having three phenyl groups which may be substituted.

The alkyl group of R in the general formula (2) is preferably a C _{2 to} C ₂₀ alkyl group, and more preferably a C _{4 to} C ₁₆ alkyl group. The aryl group of R in the general formula (2) is preferably a phenyl group which may be substituted.

  Specific examples of the borane compound represented by the general formula (2) used as the curing accelerator (C) in which Y is alkylphosphine or arylphosphine include, for example, triphenylphosphine tri-p-tolylborane, tri- n-butylphosphine trifluoroborane, n-hexadodecyldi-n-butylphosphine trifluoroborane, triphenylphosphine trifluoroborane, tri-n-butylphosphine triphenylborane, triphenylphosphine triphenylborane, triphenylphosphine tri Examples include -4-methylphenylborane, triphenylphosphine tri-4-fluorophenylborane, tri-tert-butylphosphine triphenylborane, tri-tert-butylphosphine trifluoroborane, and the like. These may be used alone or in admixture of two or more. However, some of these borane compounds are excellent in storage stability but poor in solubility in the resin, and for example, there are some which need to be used after reacting in advance with the curing agent (B) or the like. Some of these borane compounds generate benzene gas by thermal decomposition when heated to 200 ° C. or higher. From the viewpoints of environment and solubility, the borane compound represented by the general formula (2) used as the curing accelerator (C) is preferably triphenylphosphine tri-p-tolylborane, tri-n-butylphosphine triphenylborane. And at least one selected from the group consisting of triphenylphosphine triphenylborane and tri-tert-butylphosphine trifluoroborane.

  Specific examples of the borane compound represented by the general formula (2) used as the curing accelerator (C) in which Y is an imidazole, an imidazole derivative or a tertiary amine salt include (e) 2-ethyl -4-methyl-imidazole triphenylborane, (f) 1,8-diazabicyclo [5.4.0] undecene-7-triphenylborane, (g) 1,5-diazabicyclo [4.3.0] nonene- Examples thereof include 5-triphenylborane. From the viewpoint of not only exhibiting a curing accelerating action equivalent to that of the above-mentioned tetraphenylphosphonium tetraphenylborate but also being particularly excellent in solubility and thermal stability in the above borane compound in which Y is an imidazole, an imidazole derivative or a tertiary amine. The borane compound represented by the general formula (2) used as a curing accelerator (C) in which Y is imidazole or an imidazole derivative or a tertiary amine is preferably (g) 1,5-diazabicyclo [4.3. 0] Nonene-5-triphenylborane.

  There is no restriction | limiting in particular if the compounding quantity of the hardening accelerator (C) in the compound for bonded magnet resins of this invention can achieve the hardening acceleration effect. However, from the viewpoint of improving the curability and fluidity at the time of moisture absorption of the resin composition, the blending amount of the curing accelerator (C) is preferably 0.000001 with respect to 100 parts by mass of the bonded magnet powder (D). It is not less than 0.6 parts by mass and more preferably not less than 0.001 parts by mass and not more than 0.3 parts by mass. In addition, the above-mentioned listed hardening accelerator (C) may be used independently and may be used in combination of 2 or more type. Moreover, you may use hardening accelerators other than the above-mentioned listed hardening accelerator (C) with the above-mentioned listed hardening accelerator (C).

  In the resin compound for Nd—Fe—B bond magnet of the present invention, boron (or boron compound) derived from the curing accelerator (C) is present. The boron content in the Nd—Fe—B based bonded magnet resin compound of the present invention can be measured as follows. The Nd—Fe—B based bonded magnet resin compound of the present invention is burned at a high temperature in an oxygen atmosphere. Then, the combustion gas is passed through the water, and the boron in the combustion gas is trapped in the water. Trapped boron in water exists as borate ions in water. The concentration of boric acid in water can be measured using a chelate resin that adsorbs borate ions. The concentration of boric acid in water can also be measured by ICP emission spectroscopic analysis. And based on the measured density | concentration of the boric acid in water, boron content in the resin compound for Nd-Fe-B type bond magnets of this invention is computable. Further, as a method for quantifying boron derived from a curing accelerator in a resin compound for Nd-Fe-B bond magnets, Nd- for magnets in a resin compound for Nd-Fe-B bond magnets with a strong acid such as aqua regia is used. There is also a method of analyzing a boron component by dissolving Fe-B magnetic powder and analyzing the recovered (boron-containing) insoluble matter by solid-state NMR analysis.

(Nd-Fe-B magnetic powder for bonded magnets (D))
The Nd—Fe—B based magnetic powder (D) for bonded magnets used in the resin compound for Nd—Fe—B based bonded magnets of the present invention is a powder for neodymium / iron / boron based magnets. An excellent bonded magnet can be produced by the excellent magnetic properties of the Nd-Fe-B magnet and the high heat resistance and high adhesive strength of the resin composition.

  The shape of the Nd—Fe—B based magnetic powder (D) for bonded magnets is preferably a flat shape (for example, the shape aspect ratio of the powder particles = the minor axis / the major axis is 0.3 or less). When the Nd—Fe—B based magnetic powder (D) for bonded magnets having a flat shape is used, the Nd—Fe—B based magnetic powder (D) for bonded magnets can be easily laminated during compression molding of the compound. Nd-Fe-B has high density and high mechanical strength because it becomes difficult to form voids and resin pools between Nd-Fe-B-based magnetic powders (D) for bonded magnets at the time of molding. -Based bonded magnets can be manufactured.

The average particle diameter (D ₅₀ ) of the Nd—Fe—B based magnetic powder (D) for bond magnet is preferably 20 μm or more and 300 μm or less, and more preferably 40 μm or more and 250 μm or less. The particle size distribution of the Nd—Fe—B based magnetic powder (D) for bonded magnets can be measured by a particle size distribution measuring device (instrumental analysis) such as weight measurement by sieving or laser diffraction, for example.

(Storage stability)
The resin compound for Nd—Fe—B based bonded magnets of the present invention has excellent storage stability by using the curing accelerator (C). The storage stability of the resin compound for Nd—Fe—B based bond magnet described in this specification is Nd—Fe—B based on a resin compound for Nd—Fe—B based bond magnet stored for a predetermined time. Resin compound for Nd-Fe-B bond magnets (for example, Nd-Fe-B bond immediately after fabrication) with very short storage time and crushing strength and bending strength of bonded magnet (compact after heat treatment) It can be evaluated by comparing the crushing strength and the bending strength of an Nd—Fe—B based bonded magnet (compact molded body after heat treatment) produced using a resin compound for magnets. An Nd-Fe-B bond magnet produced using the Nd-Fe-B bond magnet resin compound even if the Nd-Fe-B bond magnet resin compound is stored in a harsh environment for a long time. When the crushing strength and the bending strength do not decrease, it can be said that the storage stability is high. Assuming a practical environment, for example, even if the Nd—Fe—B bond magnet resin compound is stored for about 5 days in a high temperature and high humidity environment of 40 ° C./90% RH, Nd—Fe—B bond If the crushing strength and bending strength of the magnet do not change, it is predicted that no practical problems will occur. Furthermore, even if the resin compound for Nd-Fe-B bond magnets is stored for about two weeks in a high temperature and high humidity environment of 40 ° C / 90% RH, the crushing strength and the bending strength of the Nd-Fe-B bond magnets are not reduced. If there is no change, it is predicted that no problem will occur even in a mass production process in which a large amount of Nd-Fe-B bonded magnet resin compound is produced and stored for a long period of time.

(Other ingredients)
As long as the effect of the present invention is not impaired, the Nd—Fe—B based bonded magnet resin compound of the present invention includes an epoxy resin (A), a curing agent (B), a curing accelerator (C), and A compounding component other than the Nd—Fe—B based magnetic powder (D) for the bond magnet can be included. For example, the Nd—Fe—B bonded magnet resin compound of the present invention is at least one compounding component selected from the group consisting of a coupling agent, a flow aid (metal oxide), a flame retardant, and an internal lubricant. Can further be included.

(Coupling agent)
The resin compound for Nd-Fe-B bond magnets of the present invention can further enhance the adhesion between the resin composition and the magnetic powder surface by including a coupling agent. The strength can be further increased. Examples of the coupling agent include coupling agents for silane compounds such as epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane and vinyl silane, coupling agents for titanium compounds, coupling agents for aluminum chelates, and aluminum. / Zirconium-based compound coupling agents and the like.

(Flow aid)
The resin compound for Nd—Fe—B based bonded magnets of the present invention can further improve the fluidity of the resin compound for Nd—Fe—B based bonded magnets by further including a flow aid. Examples of the flow aid include inexpensive silica (for example, Aerosil), alumina that has better thermal conductivity than silica, and the like. In addition, the flow aid includes inorganic fine particles such as calcium carbonate, kaolin clay, titanium oxide, barium sulfate, zinc oxide, aluminum hydroxide, magnesium hydroxide, talc and mica. From the viewpoint of suppressing a decrease in strength of the Nd—Fe—B based bonded magnet, the average particle diameter (D ₅₀ ) of the flow aid is preferably 100 nm or less, and more preferably 10 nm or less.

(Flame retardants)
The resin compound for Nd—Fe—B based bonded magnet of the present invention can further improve the fire resistance of the resin compound for Nd—Fe—B based bonded magnet by further including a flame retardant. From the viewpoint of environmental safety, recyclability, molding processability and low cost, the flame retardant is preferably a brominated flame retardant, a phosphorus flame retardant, a hydrated metal compound flame retardant, a silicone flame retardant, a nitrogen-containing compound, It is at least one selected from the group consisting of hindered amine compounds, organometallic compounds and aromatic engineering plastics.

(Internal lubricant)
The resin compound for Nd-Fe-B bond magnets of the present invention can further reduce damage to the mold in compression molding of the resin compound for Nd-Fe-B bond magnets by further including an internal lubricant. . The internal lubricant is not particularly limited as long as it is a lubricant used in powder metallurgy. Examples of the internal lubricant include metal soaps such as zinc stearate, magnesium stearate, lithium stearate, and calcium stearate, wax lubricants such as long chain hydrocarbons, EBS (ethylene bis stearamide), and polyethylene. Can be mentioned. Also, instead of or in combination with the resin compound for Nd-Fe-B bond magnets of the present invention, a dispersion liquid of an internal lubricant is applied to the inner wall surface of the die die (the wall surface in contact with the punch). Also good.

(Content of resin composition)
The content of the resin composition with respect to the total of the resin composition and the Nd-Fe-B magnetic powder (D) for bonded magnet in the resin compound for Nd-Fe-B bonded magnet of the present invention is the resin composition and bonded magnet. Preferably they are 0.2 mass% or more and 10 mass% or less with respect to the total amount of Nd-Fe-B type magnetic powder for use, More preferably, they are 0.4 mass% or more and 5 mass% or less. By setting it as such content, the high intensity | strength of a Nd-Fe-B type bond magnet and the magnetic characteristic of a Nd-Fe-B type bond magnet can be made compatible.

(Glass transition temperature of cured resin composition)
From the viewpoint of obtaining an excellent Nd—Fe—B based bonded magnet with little decrease in strength even under severe conditions at high temperatures, the glass transition temperature of the cured resin composition is preferably 150 ° C. or higher. More preferably, it is 200 ° C. or higher. In the present specification, the glass transition temperature is a temperature at which tan δ peaks in dynamic viscoelasticity measurement.

[Nd-Fe-B bond magnet]
The Nd—Fe—B based bonded magnet of the present invention uses the Nd—Fe—B based bonded magnet resin compound of the present invention.

(Retention rate of elastic modulus of Nd-Fe-B bond magnet)
From the viewpoint that an Nd—Fe—B based bonded magnet having excellent heat resistance can be obtained, the Nd— of the present invention at 150 ° C. with respect to the elastic modulus of the Nd—Fe—B based bonded magnet of the present invention at 50 ° C. The retention rate of the elastic modulus of the Fe—B based bonded magnet is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more. Examples of methods for measuring the elastic modulus include a method of measuring a three-point bending test at temperatures of 50 ° C. and 150 ° C., a method of measuring an elastic modulus of 50 ° C. and 150 ° C. by dynamic viscoelasticity measurement, and the like. . The elastic modulus retention rate of the Nd—Fe—B based bond magnet is the same as that of the Nd—Fe—B based bond magnet of the present invention at 150 ° C. The Nd—Fe—B based bonded magnet of the present invention at 50 ° C. The value calculated by dividing by the modulus of elasticity is expressed as a percentage.

(Relative density of Nd-Fe-B bond magnet)
From the viewpoint that an Nd—Fe—B based bonded magnet having excellent magnetic properties can be obtained, the relative density of the Nd—Fe—B based bonded magnet of the present invention is the true density of the Nd—Fe—B based magnetic powder. On the other hand, it is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more.

(Crushing strength of Nd-Fe-B bond magnet)
From the viewpoint that an Nd—Fe—B bond magnet having high mechanical strength at a high temperature can be obtained, the crushing strength of the Nd—Fe—B bond magnet of the present invention at a temperature of 150 ° C. is preferably 100 MPa or more. Yes, more preferably 150 MPa or more, still more preferably 200 MPa or more.

[Method for producing Nd—Fe—B based bonded magnet]
The manufacturing method of the Nd-Fe-B bond magnet of the present invention is a first method of preparing a resin composition by mixing an epoxy resin (A), a curing agent (B) and a curing accelerator (C) dissolved in a solvent. Step 2, Nd—Fe—B based magnetic powder (D) for bonded magnet is mixed with resin composition and dried to produce Nd—Fe—B based bonded magnet resin compound, Nd—Fe— It includes a third step of compression-molding the resin compound for the B-based bonded magnet to produce a compression-molded body, and a fourth step of heat-treating the compression-molded body. And the hardening accelerator (C) used at a 1st process is at least 1 sort (s) of a borate and a borane compound.

(First step)
As described above, in the first step, the epoxy resin (A), the curing agent (B), and the curing accelerator (C) dissolved in the solvent are mixed to prepare a resin composition. For example, a mixer is used for mixing them. By dissolving the epoxy resin (A) in a solvent, the surface of the Nd—Fe—B based magnetic powder (D) for bonded magnets can be uniformly coated with the resin composition in the second step described later. The curing accelerator (C) used in the first step is at least one of borate and borane compounds.

(solvent)
If the solvent used at the 1st process of the manufacturing method of the Nd-Fe-B system bonded magnet of the present invention can dissolve an epoxy resin (A), a hardening agent (B), and a hardening accelerator (C), There is no particular limitation. For example, the solvent includes acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene and xylene. In consideration of workability, the solvent is preferably a liquid at room temperature and a boiling point of 60 ° C. or higher and 150 ° C. or lower.

(Second step)
As described above, in the second step, the Nd—Fe—B based magnetic powder (D) for bonded magnets is mixed with the resin composition and dried to produce a resin compound for Nd—Fe—B based bonded magnets. For the mixing and drying, for example, a mixing shaker, a tumbler mixer, a V-type mixer, a double cone type mixer, a ribbon type mixer, a Nauter mixer, a Henschel mixer, a super mixer, and the like can be used.

(Third step)
As described above, in the third step, the Nd—Fe—B based bonded magnet resin compound is compression molded to produce a compression molded body. The higher the pressure at the time of compression molding, the higher the magnetic flux density and the higher strength Nd—Fe—B based bonded magnet can be obtained. For example, the molding pressure at the time of compression molding is preferably 500 MPa or more and 2500 MPa or less. Further, from the viewpoint of mass productivity and mold life, the molding pressure at the time of compression molding is preferably 1400 MPa or more and 2000 MPa or less. From the viewpoint that an Nd—Fe—B based bonded magnet having good magnetic properties and high mechanical strength can be produced, the density of the compression molded body is determined as follows. Nd—Fe—B based magnetic powder for bonded magnet (D) The true density is preferably 75% or more and 86% or less, more preferably 80% or more and 86% or less.

(Fourth process)
As described above, in the fourth step, the compression molded body is heat treated. Thereby, the resin composition in a compression molding body can be hardened completely. Therefore, the heat treatment temperature is not particularly limited as long as the temperature can sufficiently cure the thermosetting resin. For example, the heat treatment temperature is preferably 150 ° C. or higher and 300 ° C. or lower, more preferably 175 ° C. or higher and 250 ° C. or lower. Moreover, in order to suppress the oxidation of the Nd—Fe—B based magnetic powder (D) for bonded magnets, the heat treatment can be performed in an inert atmosphere. In addition, when the heat treatment temperature is higher than 300 ° C., oxidation of the Nd—Fe—B based magnetic powder (D) for bond magnets or deterioration of the cured product of the resin composition occurs due to a trace amount of oxygen inevitable in production. Sometimes. From such a viewpoint, the heat treatment temperature is preferably 300 ° C. or lower. From the above viewpoint, the heat treatment temperature holding time is preferably 1 minute to 4 hours, and more preferably 5 minutes to 1 hour.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

[Resin composition]
Resin composition used for resin compound for Nd-Fe-B bond magnet for the purpose of grasping the curing characteristics of resin compound for Nd-Fe-B bond magnet before evaluating Nd-Fe-B bond magnet Thermal analysis of the product and heat resistance evaluation of the cured product were performed. Table 1 shows the composition and evaluation results of the resin composition used in the test. In addition, the unit of the compounding quantity of each component in Table 1 is a mass part.

(Thermal analysis and heat resistance evaluation)
The thermal characteristics of the obtained resin composition were evaluated using a differential scanning calorimeter (trade name: DSC7, manufactured by PERKIN ELMER). The analysis was performed under a N ₂ atmosphere at a temperature rising rate of 10 ° C./min, and the exothermic peak temperature and the calorific value of each resin composition were measured. These measurements were performed on the resin composition immediately after compounding and the resin composition stored for 5 days in a high temperature and high humidity environment of 40 ° C./90% RH. The value calculated by subtracting the calorific value of the resin composition stored for 5 days in a high-temperature and high-humidity environment of 40 ° C./90% RH from the calorific value of the resin composition immediately after compounding is the heat value of the resin composition immediately after compounding. The calorific value reduction rate was calculated by dividing by the amount.
Moreover, the weight loss at the time of high temperature was measured using the differential thermothermal weight simultaneous measurement apparatus (TG-DTA, EXSTAR6000, Hitachi High-Tech Science Co., Ltd.), and the heat resistance parameter | index was obtained. The measurement was performed by measuring a change in weight when an Al pan was filled with a sample (about 10 mg or more and about 20 mg or less) and heated from 25 ° C. to 500 ° C. at a heating rate of 10 ° C./min in an N ₂ atmosphere. The weight reduction rate was calculated based on the mass of the sample at the time. The results of these thermal analyzes are summarized in Table 1.

(Preparation of resin composition)
The resin composition used for the above-mentioned evaluation of thermal characteristics was produced as follows.
A salicylaldehyde type epoxy resin (epoxy equivalent 168 g / eq., Softening point 64 ° C., Nippon Kayaku Co., Ltd., trade name EPPN-502H) was used as the epoxy resin (A). In addition, phenol novolac resin (hydroxyl equivalent: 106 g / eq., Manufactured by Hitachi Chemical Co., Ltd., trade name: HP-850N) was used as the curing agent (B). The following curing accelerators (C-1 to 10) were used as the curing accelerator (C). Furthermore, 800 parts by mass of 2-butanone was used as a solvent for dissolving the epoxy resin (A) with respect to 100 parts by mass of the epoxy resin (A). These raw materials were mixed in a plastic container at a blending ratio shown in Table 1, and stirred at a rotation speed of 40 min ⁻¹ with a mix rotor. After stirring for 1 hour, the obtained resin solution was concentrated, and the solvent was sufficiently removed by reducing the pressure using a vacuum pump (attainment pressure: about 6.7 × 10 ⁻² Pa). Thus, the resin compositions 1-10 were produced.

(1) Curing accelerator C-1: Tetraphenylphosphonium tetra-p-tolylborate (Hokuko Chemical Co., Ltd., product name TPP-MK, melting point 247-250 ° C.)
(2) Curing accelerator C-2: Tetraphenylphosphonium tetraphenylborate (Hokuko Chemical Co., Ltd., product name TPP-K, melting point 304-306 ° C.)
(3) Curing accelerator C-3: Triphenylphosphine triphenylborane (manufactured by Hokuko Chemical Co., Ltd., product name TPP-S, melting point 210-213 ° C.)
(4) Curing accelerator C-4: Tetra-n-butylphosphonium tetraphenylborate (manufactured by Nippon Chemical Industry Co., Ltd., product name PX-4PB melting point 230 ° C.) was used.
(5) Curing accelerator C-5: Tri-tert-butylphosphonium tetraphenylborate (manufactured by Tokyo Chemical Industry Co., Ltd., melting point 239 ° C.)
(6) Curing accelerator C-6: Tetrabutylammonium tetraphenylborate (manufactured by Tokyo Chemical Industry Co., Ltd., melting point 235 ° C.)
(7) Curing accelerator C-7: 1,5-diazabicyclo [4.3.0] nonene-5-tetraphenylborate (product name DBNK, melting point 130 ° C., manufactured by Hokuko Chemical Co., Ltd.)
(8) Curing accelerator C′-8: Triphenylphosphine (Hokuko Chemical Co., Ltd., product name TPP, melting point 80 ° C.)
(9) Curing accelerator C′-9: 2-cyanoethyl-4-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., product name 2PZ-CN, melting point 57 ° C.) was used.
(10) Curing accelerator C′-10: 1,8-diazabicyclo [5,4,0] undec-7-ene (manufactured by San Apro Co., Ltd., product name DBU)

[Evaluation results of resin composition]
From Table 1, the resin compositions 1-7 which used the borate or borane compound as a hardening accelerator (C) are compared with the resin compositions 8-10 which do not use the borate or borane compound as a hardening accelerator (C). In all cases, there was little decrease in the calorific value of the resin composition stored for 5 days in a high temperature and high humidity environment of 40 ° C./90% RH. From this, even if the resin compositions 1 to 7 are stored for 5 days in a high temperature and high humidity environment of 40 ° C./90% RH, the curing of the resin compositions 1 to 7 hardly progresses, but the resin compositions 8 to 10 are When the resin compositions 8 to 10 are stored for 5 days in a high-temperature and high-humidity environment of 40 ° C./90% RH, curing is considered to proceed gradually.
In the resin compositions 1 to 7, even when the resin composition was heated to a high temperature of 200 ° C. and 250 ° C., the weight reduction rate was small. On the other hand, in the resin compositions 8 to 10, when the resin composition was heated to a high temperature of 200 ° C. and 250 ° C., the weight reduction rate was very large. Since the resin compositions 1 to 10 are cured at 200 ° C. and 250 ° C., the heat resistance of the cured products of the resin compositions 1 to 7 is higher than that of the cured products of the resin compositions 8 to 10. It can be said that it is superior to sex.
Since the epoxy resin (A) and the curing agent (B) of the resin compositions 1 to 10 are the same, these differences between the resin compositions 1 to 7 and the resin compositions 8 to 10 are the curing accelerator (C). Depends on whether or not is a borate or borane compound. Therefore, it has been found that by using borate or a borane compound as the curing accelerator (C), the storage stability of the resin composition is improved and the heat resistance of the cured product of the resin composition is also improved.

[Nd-Fe-B bond magnet]
The Nd—Fe—B based bonded magnets of Examples 1 to 7 and Comparative Examples 1 to 3 were produced, and the density and crushing strength were measured for the produced Nd—Fe—B based bonded magnets.

(Preparation of resin compound for Nd-Fe-B bond magnet)
Salicylaldehyde novolak type epoxy resin (epoxy equivalent 168 g / eq., Softening point 64 ° C., Nippon Kayaku Co., Ltd., trade name EPPN-502H) was used as the epoxy resin (A). In addition, phenol novolac resin (hydroxyl equivalent: 106 g / eq., Manufactured by Hitachi Chemical Co., Ltd., trade name: HP-850N) was used as the curing agent (B). Furthermore, said hardening accelerator (C-1-10) was used as a hardening accelerator (C). Further, Nd—Fe—B powder (manufactured by Moricope Magnequench, trade name MQP-B, average particle size: 100 μm) was used as powder (D) for bond magnet. Furthermore, 30 parts by mass of 2-butanone was used as a solvent for dissolving the epoxy resin (A) with respect to 100 parts by mass of the bonded magnet powder. These raw materials were put into a eggplant-shaped flask having a volume of 300 mL at a blending ratio shown in Table 2, and stirred at 25 ° C. in an evaporator for about 30 minutes. Subsequently, the inside of the evaporator is depressurized, the agglomerated bonded magnet resin compound is taken out from the eggplant-shaped flask, and the pressure is reduced using a vacuum pump (attainment pressure: about 6.7 × 10 ⁻² Pa), so that the solvent is sufficient Removed. After removing the solvent, the agglomerated bonded magnet resin compound was coarsely pulverized, and coarse particles were removed with a 100 mesh sieve to adjust the particle size.

(Preparation of Nd-Fe-B bond magnet)
Next, 0.3 parts by mass of calcium stearate as an internal lubricant was mixed with the resin compound for Nd—Fe—B based bonded magnet immediately after 100 parts by mass, and the mixture was stirred for about 1 hour with a V-type mixer. . The obtained resin compound for bonded magnets containing an internal lubricant was molded into a cylindrical compression molded body having an outer diameter of 11.3 mm and a height of 8 mm at a molding pressure of 2000 MPa using a hydraulic press. The obtained cylindrical compression molded body was heated for 10 minutes at a temperature of 200 ° C. in a nitrogen gas (N ₂ ) atmosphere to prepare a test piece of an Nd—Fe—B based bonded magnet. Similarly, a test piece of an Nd—Fe—B based bond magnet was prepared for a resin compound for an Nd—Fe—B based bonded magnet stored for 5 days in an environment of 40 ° C./90% RH.

(Crushing strength test)
Using a universal compression tester (manufactured by Shimadzu Corporation, trade name: AG-10TBR), applying a compression pressure from the height direction to each of the above test pieces, the test piece was destroyed by the compression pressure. The crushing strength (MPa) was calculated from the maximum value of the compression pressure. Table 2 summarizes the results of the crushing strength of the Nd—Fe—B based bonded magnet. In addition, Nd- preserved for 5 days in an environment of 40 ° C./90% RH with respect to the crushing strength of the Nd—Fe—B based bonded magnet prepared using the resin compound for the Nd—Fe—B based bonded magnet immediately after fabrication. The storage stability of the Nd-Fe-B bond magnet resin compound was examined from the strength reduction rate of the crushing strength of the Nd-Fe-B bond magnet produced using the Fe-B bond magnet resin compound. It shows that the storage stability of the resin compound for Nd-Fe-B based bonded magnets is worse as the strength reduction rate is larger. When the strength reduction rate is a negative value, the Nd—Fe—B based bonded magnet of the Nd—Fe—B based bonded magnet is stored when the resin compound for Nd—Fe—B based bonded magnet is stored for 5 days in an environment of 40 ° C./90% RH. This is a case where the crushing strength is high.

Table 2 below shows the composition of the resin compound powder for Nd-Fe-B bond magnets and the density and crushing strength test results of the obtained Nd-Fe-B bond magnets.

The Nd—Fe—B based bond magnets of Examples 1 to 7 all have a crushing strength even when the Nd—Fe—B based bond magnet resin compound is stored for 5 days in an environment of 40 ° C./90% RH. There was little decrease in. In particular, Example 4 in which tetra-n-butylphosphonium tetraphenylborate was used as the curing accelerator (C), the resin compound for Nd—Fe—B based bonded magnet was placed in an environment of 40 ° C./90% RH for 5 days. On the contrary, the crushing strength was increased by storage. Furthermore, when Examples 1-7 are compared, Example 7 which consists of a 5-membered heterocyclic compound has a somewhat large intensity | strength fall. On the other hand, Example 3 using a borane compound (triphenylphosphine triphenylborane) was found to have a low absolute value of the crushing strength, although the strength decrease was small. These results are consistent with the DSC measurement results in Table 1.
On the other hand, the Nd—Fe—B bond magnets of Comparative Examples 1 to 3 had a large reduction in the crushing strength, and the storage stability of the resin compound for bond magnets was poor. Considering the results in Table 1, this is considered to be due to the poor storage stability of the resin composition. With such a resin compound for Nd—Fe—B bond magnets with poor storage stability, it becomes difficult to produce Nd—Fe—B bond magnets.

  The resin compound for Nd—Fe—B based bonded magnet of the present invention is excellent in storage stability. Therefore, by using the Nd-Fe-B bonded magnet resin compound of the present invention, the Nd-Fe-B bonded magnet resin compound is stored at high temperature and high humidity. A decrease in strength of the system bond magnet can be suppressed. Further, the Nd—Fe—B based bonded magnet produced using the Nd—Fe—B based bonded magnet resin compound of the present invention has high mechanical strength and good heat resistance. By using such a resin compound for Nd-Fe-B bond magnets, it becomes possible to stably provide high-performance Nd-Fe-B bond magnets that are excellent in heat resistance even at high temperatures and high humidity. , Its industrial value is high.

Claims (9)

A resin composition comprising an epoxy resin (A), a curing agent (B) and a curing accelerator (C), and an Nd-Fe-B magnetic powder (D) for a bond magnet,
The curing accelerator (C) is a volley preparative represented by the following general formula (1), a resin compound for Nd-Fe-B based bonded magnet.
X ⁺ B ⁻ (R) ₄ (1)
(In the formula (1), B represents boron, X represents at least one of arylphosphonium salt, imidazole or imidazole derivative salt, and quaternary ammonium salt, and R consists of an alkyl group, an aryl group, and a fluoro group. 1 type selected from the group.) 2. The resin compound for an Nd—Fe—B based bonded magnet according to claim 1, wherein X in the general formula (1) is at least one of an arylphosphonium salt and a quaternary ammonium salt. The resin compound for Nd-Fe-B bond magnets according to claim 1 or 2, wherein X in the general formula (1) is an arylphosphonium salt.   Content of the said hardening accelerator (C) is 0.000001 mass part or more and 0.6 mass part or less with respect to 100 mass parts of Nd-Fe-B type magnetic powder (D) for bonded magnets. 4. The resin compound for Nd—Fe—B based bonded magnet according to any one of 3 above.   The Nd-Fe according to any one of claims 1 to 4, wherein the epoxy resin is at least one selected from the group consisting of a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, and a naphthol novolak type epoxy resin. -Resin compound for B-based bonded magnet.   The resin compound for Nd-Fe-B bond magnets according to any one of claims 1 to 4, wherein the epoxy resin has a salicylaldehyde novolak type structure. The curing agent (B) is a phenol resin,
The ratio of the active group in the curing agent (B) that reacts with the epoxy group of the epoxy resin (A) to 1 equivalent of the epoxy group of the epoxy resin (A) is 0.5 or more and 1.5 or less. The resin compound for Nd-Fe-B type bond magnets of any one of -6.   An Nd—Fe—B based bonded magnet using the resin compound for an Nd—Fe—B based bonded magnet according to claim 1. First step of preparing a resin composition by mixing an epoxy resin (A), a curing agent (B), and a curing accelerator (C) dissolved in a solvent, Nd-Fe-B magnetic powder for bond magnet (D ) Is mixed with the resin composition and dried to produce a Nd—Fe—B based bonded magnet resin compound, and the Nd—Fe—B based bonded magnet resin compound is compression molded and compressed. and a fourth step of heat-treating the third step of preparing a molded body, and the compression molded body, wherein the curing accelerator (C) is a volley preparative represented by the following general formula (1), inter-Nd Manufacturing method of Fe-B type bonded magnet.
X ⁺ B ⁻ (R) ₄ (1)
(In the formula (1), B represents boron, X represents at least one of arylphosphonium salt, imidazole or imidazole derivative salt, and quaternary ammonium salt, and R consists of an alkyl group, an aryl group, and a fluoro group. 1 type selected from the group.)