JP2015035538A - Rare-earth-ferrous bond magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare earth bond magnet, excellent in magnetic flux density, having density higher than density of a compact before heat hardening.SOLUTION: The rare-earth-ferrous bond magnet formed by making a rare-earth-ferrous magnet compound containing rare-earth-ferrous magnet flakes and a thermosetting resin composition, press-molding the compound to make a compressed compact, and heat hardening the compressed compact has density higher than density of the compressed compact before heat hardening, with heating hardening of the compressed compact.

Description

  The present invention relates to a rare earth-iron based bonded magnet in which rare earth-iron based magnet flakes are bonded with a resin, and more particularly, a rare earth-iron based bonded magnet manufactured by compression molding by bonding rare earth-iron based magnetic flakes with a resin. About.

Since rare earth-iron permanent magnets have excellent magnetic properties, they are used in a wide range of fields such as general household electrical appliances, acoustic devices, medical devices, general industrial devices such as rotating devices such as motors. Among these permanent magnets, rare earth-iron based bonded magnets composed of a combination of rare earth-iron based magnetic flakes and a resin composition responsible for their bonding take advantage of the high degree of freedom in shape, and in the above usage examples This contributes to miniaturization and high performance of equipment.
The molding process of the rare earth-iron-based bonded magnet is classified into compression molding, injection molding, extrusion molding, and the like, and the resin composition to be used differs depending on these molding processes. For example, a thermosetting resin composition is used for compression molding, and a thermoplastic resin composition is used for injection molding and extrusion molding, and these are generally used depending on the application of the permanent magnet. Among them, rare earth-iron-based bonded magnets produced by a compression molding process using a thermosetting resin composition have a higher content of rare earth-iron-based magnet flakes inside permanent magnets than those by other molding processes. And a permanent magnet exhibiting higher magnetic properties can be obtained.

  On the other hand, it is known that rare earth-iron-based bonded magnets have a magnetic flux loss that does not recover even if they are exposed to a high temperature for a long period of time and then re-magnetized after returning to room temperature. This is generally called permanent demagnetization. Rare earth-iron-based bonded magnets have a primary correlation between the volume fraction of residual voids in the magnet and permanent demagnetization regardless of the production method such as injection molding or compression molding. It is known that the demagnetization factor also decreases. Furthermore, as a major factor of permanent demagnetization, moisture and oxygen taken into the air gaps inside the rare earth-iron bond magnets promote structural changes such as oxidation and corrosion of the rare earth-iron magnet flakes inside the magnet. It is known to do. In addition, in rare earth-iron based bonded magnets in which the volume fraction of rare earth-iron based magnetic flakes exceeds 80 vol%, brittle fracture of rare earth-iron based magnetic flakes that occurs during magnet densification transients due to compression molding is caused by oxidation. It means the production of a new surface of rare earth-iron magnet flakes that are prone to corrosion. Thus, reducing the residual void inside the magnet as much as possible can be regarded as an effective means for suppressing permanent demagnetization of the rare earth-iron-based bonded magnet.

  In response to the problem of reducing residual voids inside the rare earth-iron bond magnet, the present inventors, as disclosed in Non-Patent Document 1, in the rare earth-iron bond magnet obtained by compression molding, And a thermosetting resin composition comprising a solid unsaturated polyester alkyd, an allyl copolymerizable monomer and an organic peroxide, and a rare earth-iron magnet flake melt-kneaded with the resin composition. In addition, the volume fraction of the magnet material is maintained at approximately 80 vol% or more at a molding pressure of 1 GPa or less by performing compression molding of the granules at approximately room temperature, and only the residual voids are volume integrated. It has been found that a reduction in rate of less than approximately 1 vol% can be realized. The rare earth-iron bond magnet using the thermosetting resin made of the unsaturated polyester alkyd, the allyl copolymerizable monomer and the organic peroxide is a rare earth using the thermosetting resin made of an epoxy resin. -As compared with iron-based bonded magnets, it has been found that the spring back when taken out from the molding die after compression molding is suppressed, and the dimensional accuracy is excellent.

F. Yamashita, T. Suzuki, H. Komura, M. Nakano, and H. Fukunaga, “Improvement of long-term flux stability in Nd-Fe-B bonded magnet fabricated from fully-dense powder compaction technique”, Proceedings of 22nd International Workshop on Rare-Earth Permanent Magnets and their Applications, Nagasaki, 2012, p.467-470

  According to the technique disclosed in Non-Patent Document 1, it is effective for improving the dimensional accuracy by increasing the density of the rare earth-iron bond magnet and suppressing the spring back. However, when the compact after compression molding is heated and the thermosetting resin contained in the compact is thermoset to form a rare earth-iron bond magnet, the compact expands and the density decreases slightly. Therefore, the decrease in magnetic flux density cannot be avoided.

  This invention is made | formed in view of the said situation, Comprising: The problem which it is going to solve is providing a rare earth bond magnet which is high density compared with the molded object before heat-curing, and was excellent in magnetic flux density.

  As a result of intensive studies to achieve the above object, the present inventors have made the density of the rare-earth bonded magnet that is the finished product higher than that of the compression-molded body that is the form before the heat-curing. The present invention has been completed by finding that it can contribute to the realization of an excellent magnetic flux density.

  That is, the present invention creates a rare earth-iron-based magnet compound containing a rare earth-iron-based magnet flake and a thermosetting resin composition, compression-molds the compound to form a compression-molded body, and heat-cures the compression-molded body A rare earth-iron-based bonded magnet, wherein the density of the compression-molded body is higher than that of the compression-molded body before heat-curing by heat-curing the compression-molded body. The present invention relates to a bonded magnet.

In the rare earth-iron based bonded magnet of the present invention, it is preferable that the thermosetting resin composition is contained in an amount of 3 wt% to 4 wt% with respect to the rare earth-iron based magnet flake.
The thermosetting resin composition preferably contains an unsaturated polyester alkyd, an allylic copolymerizable monomer, and an organic peroxide. At this time, the unsaturated polyester alkyd (A) and the allylic It is preferable that the copolymerizable monomer (B) is contained in a mass ratio of 30 wt% ≧ B / (A + B) ≧ 20 wt%. More preferably, the unsaturated polyester alkyd (A) and the allylic copolymerizable monomer (B) are contained in a mass ratio of 30 wt% ≧ B / (A + B) ≧ 25 wt%.
The unsaturated polyester alkyd is one of a terephthalic acid unsaturated polyester resin or an isophthalic acid unsaturated polyester resin, and the allyl copolymerizable monomer is triallyl isocyanurate or trimethallyl isocyanate. It is preferable that either one of nurate is used.
Further, the compression molded body preferably has a volume fraction of residual voids contained therein of 6 vol% or more and 12 vol%.

  The rare earth-iron-based bonded magnet of the present invention is in a high-density form because the volume is contracted as compared with a compression molded body that is a form before heat curing. That is, the density of the bonded magnet after thermosetting is increased, and a magnet having an excellent magnetic flux density can be obtained.

FIG. 1 is a diagram showing a density change before and after thermosetting with respect to density before compression of the compression molded bodies of Example 1 (Sample 1 to Sample 4) and Comparative Example 1. FIG. 2 is a diagram showing a density change before and after thermosetting with respect to the density before thermosetting of the compression molded bodies of Example 2 (Sample 5 to Sample 7) and Comparative Example 1. FIG. 3 is a diagram showing density changes before and after thermosetting of the compression molded bodies of Example 3 (Sample 8 to Sample 11) and Comparative Example 1 before thermosetting. FIG. 4 is a graph showing density changes before and after thermosetting with respect to the volume fraction of residual voids before thermosetting of the compression molded body of Example 4 (Sample 3, Sample 4, Sample 6, and Sample 7).

  The rare earth-iron based bonded magnet of the present invention comprises a rare earth-iron based magnet flake and a thermosetting resin composition.

As described above, it is considered that the conventional rare earth-iron-based bonded magnet undergoes volume expansion (density reduction) when undergoing a heating process during manufacturing. One of the causes of such dimensional changes is that the thermosetting resin itself, such as the epoxy resin and unsaturated polyester resin that constitutes the bonded magnet, tends to shrink during the thermosetting process, but the residual voids slightly contained in the molded product. Since (void) expands in the heating process, the dimension of the bonded magnet after thermosetting is expected to be slightly larger than the compression molded body. In addition to this, various factors such as stress at the time of compression molding can be considered as factors of the dimensional change.
Hereinafter, each component which comprises the rare earth-iron type bonded magnet of this invention is explained in full detail.

[Rare earth-iron magnet flakes]
The rare earth-iron-based magnet flake according to the present invention is, for example, an R-Fe-B-based magnet (where R is a rare-earth element such as Ce, Pr, Nd, Gd, Tb, Dy, and Ho, including Y) or Fe R—Fe (Co) —B based magnet in which a part of is replaced with Co (where R represents the above-mentioned meaning), one of Si, Al, Nb, Zr, Hf, Mo, Ga, P, C or R-Fe-BM type magnet or R-Fe (Co) -BM type magnet using a combination of two or more (where R represents the aforementioned meaning, M is Si, Al, Nb, Zr, Hf, Mo, Ga, P, C represents one or a combination of two or more), R ₂ Fe ₁₄ B, R ₂ Fe (Co) ₁₄ B nanocrystalline structure having an alloy composition consisting of inevitable impurities (nanocrystalline) Or αFe and R ₂ Fe ₁₄
B, magnetically isotropic rare earth-iron rapidly solidified flakes including a nanocomposite with R ₂ Fe (Co) ₁₄ B (wherein R represents the aforementioned meaning) can be used. .
In addition, as the rare earth-iron-based magnet flakes, Sm-Fe-N using Sm-Fe-N-based magnet, Hf, Zr, Si, Nb, Ti, Ga, Al, Ta and C, or a combination of two or more thereof. M
Sm ₂ Fe ₁₇ having an alloy composition of '-N magnet (where M' represents one or more of Hf, Zr, Si, Nb, Ti, Ga, Al, Ta and C) and inevitable impurities Nx (x≈3) nanocrystalline structure, or αFe and Sm ₂ Fe ₁₇ Nx (
Magnetically isotropic rare earth-iron rapidly solidified flakes including nanocomposites with x≈3) can be used.

[Thermosetting resin composition]
The thermosetting resin composition according to the present invention includes an unsaturated polyester alkyd (A), an allylic copolymerizable monomer (B), and an organic peroxide.

The unsaturated polyester alkyd (A) comprises a dicarboxylic acid component and a glycol (diol) component.
The unsaturated polyester alkyd (A) according to the present invention preferably has a melting point of 80 to 120 ° C.

The dicarboxylic acid component is preferably composed of phthalic acid and fumaric acid, and phthalic acid or a derivative thereof and fumaric acid are used as raw materials. In the following description of the present specification, the term “phthalic acid” includes the meaning of “phthalic acid or a derivative thereof”, that is, includes phthalic acid, terephthalic acid, isophthalic acid, and derivatives thereof.
The use ratio of phthalic acid / fumaric acid is preferably 5/5 to 1/9, particularly 4/6 to 2/8 (molar ratio).

The glycol component is preferably 1,4-butanediol alone, or 1,4-butanediol and other glycols in combination. At this time, the ratio of 1,4-butanediol / other glycol is preferably 7/3 to 10/0, more preferably 8/2 to 9.5 / 0.5 (molar ratio).
Other glycol components used in combination with 1,4-butanediol include ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, 1, Addition of 5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, hydrogenated bisphenol A, ethylene oxide or propylene oxide of bisphenol A You can list things. Here, propylene glycol, neopentyl glycol, or dipropylene glycol can be preferably used as the other glycol component.

  Examples of the allyl copolymerizable monomer (B) according to the present invention include bifunctional monomers such as diallyl isophthalate, diallyl terephthalate, and diallyl orthophthalate, or triallyl isocyanurate and trimerene which are triazine ring compounds. And trifunctional monomers such as taryl isocyanurate. These may be used alone or in combination of two or more.

In general, the copolymerizable monomer includes a monomer having a vinyl group (CH ₂ ═CH—) and an allyl group (CH ₂ ═CH—CH ₂ — or CH ₂ ═C (CH ₃ ) —CH _2. It is classified into a monomer having-). In the latter monomer, the allyl group is stabilized by the resonance structure even when activated by the peroxide radical that is a polymerization initiator (degenerate chain transfer reaction (in the case of an allyl group)). _{: ~R · + CH 2 = CH} -CH 2 -X → ~RH + CH 2 = CH- · CH-X⇔ · CH 2 -CH = CH-X), a chain reaction of the polymerization reaction is inhibited. Due to this resonance action, the monomer having an allyl group is inactive in the normal temperature region, which is advantageous in terms of storage stability at normal temperature of a compression molded body (bonded magnet material before curing) prepared later. In addition, all of the allyl copolymerizable monomer has a high vapor pressure and hardly volatilizes. From these points as well, by using the allyl copolymerizable monomer (B), a rare earth-iron bond magnet compound having excellent storage stability at room temperature can be obtained.

  The ratio (concentration) of the unsaturated polyester alkyd (A) and the allylic copolymerizable monomer (B) is a mass ratio, preferably B / (A + B) = 20 wt% to 30 wt%, more preferably. B / (A + B) is 25 wt% or more and 30 wt% or less.

  An organic peroxide can be illustrated as a polymerization initiator concerning this invention. Examples of the organic peroxide include methyl ethyl ketone peroxide, cyclohexanone peroxide, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, p- Menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxylaurate , T-butyl peroxybenzoate and the like.

  Furthermore, in the present invention, p-benzoquinone, naphthoquinone, p-toluquinone, 2,5-diphenyl-p-benzoquinone, 2,5-acetoxy-p-benzoquinone, hydroquinone, pt-butylcatechol, 2 , 5-di-t-butylhydroquinone, di-t-butyl-p-cresol, hydroquinone monomethyl ether, and the like. These polymerization inhibitors can be used in combination of two or more. In addition, the usage-amount of a polymerization inhibitor is 0.5 mass part or less with respect to 100 mass parts of total mass of the said unsaturated polyester alkyd (A) and the said allylic copolymerizable monomer (B).

  In the present specification, the unsaturated polyester resin (resin composed of unsaturated polyester alkyd and allyl copolymerizable monomer), a thermosetting resin composition containing a polymerization initiator (organic peroxide), As long as the effects of the present invention are not impaired, a polymerization inhibitor, a coupling agent, an antioxidant, a lubricant and the like can be added as necessary.

  In the rare earth-iron based bonded magnet of the present invention, it is preferable that the thermosetting resin composition is contained in an amount of 3 wt% to 4 wt% with respect to the rare earth-iron based magnet flake.

[Production of rare earth-iron bond magnets]
The rare earth-iron-based bonded magnet of the present invention can be suitably manufactured by the method disclosed in Non-Patent Document 1 described above, and a specific procedure is described below.
First, unsaturated polyester alkyd (A) and allylic copolymerizable monomer (B) are melt-kneaded to obtain unsaturated polyester resin, and polymerization initiator (liquid or powder) and other additives are added thereto. A thermosetting resin composition is obtained by melt-kneading. Next, the thermosetting resin composition is melted using, for example, a mixing roll, and a predetermined amount of the rare earth-iron-based magnet flakes are added thereto and kneaded to obtain a melt-kneaded product, which is kneaded at room temperature. Get things.
Alternatively, unsaturated polyester alkyd (A), allyl copolymerizable monomer (B), polymerization initiator (liquid or powder), the rare earth-iron magnet flakes and other additives are mixed together in advance. For example, simultaneously with the production of a molten unsaturated polyester resin that is a copolymerizable monomer solution of the unsaturated polyester alkyd at a temperature near the melting point of the unsaturated polyester alkyd using a mixing roll, the molten resin and the rare earth -Kneading with iron-based magnet flakes is allowed.
Here, by kneading the rare earth-iron-based magnet flakes in the molten state of the thermosetting resin composition, the voids in the melt-kneaded material and further the rare-earth-iron-based bonded magnet compound described later are reduced. From this point of view, it is desirable to carry out this process in a so-called solvent-free type in which the process is carried out without a solvent.
The melt-kneading is performed by a conventional method using a kneading machine that can be used with a normal thermosetting resin molding material, such as a mixing roll, a roll mill, a kneader, or a twin-screw extruder.

Next, the obtained melt-kneaded product is cooled to room temperature, crushed, and classified to obtain a compound for a rare earth-iron bond magnet that is in the form of granules. In addition, since the melt-kneaded material concerning this invention has a viscoelastic element, the crushing by shear compression is more desirable than the crushing by the impact force using brittleness. Generally, in comparison with crushing by impact force, crushing by shearing force often has a relatively small particle size and a narrow distribution width. Specifically, it is desirable to use a crushing method such as an electric stone mill having a shear compression action in principle. At that time, the particle size of the granular rare earth-iron-based bonded magnet compound can be controlled by adjusting the gap between the driving plate and the fixed platen.
The particle size range of the rare earth-iron based bonded magnet compound according to the present invention is preferably about 53 to 500 μm, for example, in consideration of the filling property into a mold cavity such as a mold in a subsequent process.
In addition, improvement of powder fluidity related to filling of the classified rare earth-iron bond magnet compound into the mold cavity, or compression of the classified rare earth-iron bond magnet compound with the mold cavity wall surface For the purpose of reducing friction, a general external lubricant such as a higher fatty acid metal soap may be dry-mixed with the rare earth-iron bond magnet compound. In addition, when adding an external lubricant, the addition amount is preferably 0.5 parts by mass or less with respect to 100 parts by mass of the rare earth-iron-based bonded magnet compound.

Next, the rare earth-iron-based bonded magnet compound having the above-mentioned particle size adjusted is filled in the mold cavity with the rare-earth-iron-based bonded magnet compound, and the temperature below the melting point of the granule (for example, room temperature: 20 ° C. ± 15 ℃ (5-35 ℃)), the pressure above the yield stress of the thermosetting resin composition, for example, about 0.6 GPa to 1.5 GPa, for example, about uniaxial about 0.8 to 1.0 GPa To give a compression-molded body having a specific shape. Thereafter, the pressure is released, and the compression molded body is released from the mold cavity.
At this time, in the compression molded body to be obtained, the volume fraction of residual voids in the compression molded body is preferably 6 vol% or more and 12 vol% or less.

Finally, in the released compression molded body, the thermosetting resin composition (that is, unsaturated polyester resin) constituting the molded body is heat-cured to obtain a rare earth-iron bond magnet. The thermosetting treatment can be performed in the air.
For example, while the compression molded body is constrained by the support, the thermosetting resin composition constituting the compression molded body is heated and cured to produce a rare earth-iron bond magnet integrated with the support. You can also
The rare earth-iron-based bonded magnet according to the present invention and the compression-molded body before curing of the bonded magnet are advantageously and suitably manufactured through the above-described steps, but the manufacturing method is limited to these steps. It is not something.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to this.

The rare earth-iron-based magnet flakes and unsaturated polyester alkyd used in the examples are as follows.
[Rare earth-iron magnet flakes]
Nd ₁₂ Fe ₇₇ Co ₅ B ₆ (atomic%) having an alloy composition close to the Nd ₂ Fe ₁₄ B stoichiometric composition, a particle diameter of 150 μm or less (measured by a dry sieving method (JIS Z 8815)) obtained by rapidly solidifying a molten alloy Rare earth-iron magnet flakes were used.

[Unsaturated polyester alkyd]
A reactor equipped with a stirrer, a distillation pipe, a nitrogen gas introduction pipe and a thermometer was charged with 100 mol% of 1,4-butanediol and 40 mol% of dimethyl terephthalate. As a catalyst, 0.02 mol% of titanic acid tetra-n-butoxide and 0.03 mol% of antimony trioxide were charged with respect to all acid components (dimethyl terephthalate and fumaric acid described later). Transesterification was performed by raising the internal temperature to 140 ° C. and further raising the temperature to 200 ° C. over 1.5 hours to distill methanol. Next, the internal temperature was lowered to 160 ° C., 60 mol% of fumaric acid and 150 ppm of hydroquinone (based on the amount [mass] of fumaric acid charged) were charged, and the internal temperature was increased to 155 ° C. while flowing nitrogen gas at 300 mL / min. The internal temperature was raised to 160 ° C. over 0 hours, further raised to 210 ° C. over 2.5 hours, and the reaction was continued at the same temperature for 5.5 hours. During the reaction time, the nitrogen flow rate was increased to 680 mL / min during the latter 4.0 hours. After completion of the reaction, the reaction product was discharged, cooled and crystallized, and then pulverized using a Henschel mixer to obtain particulate unsaturated polyester alkyd.
In the obtained unsaturated polyester alkyd, the usage-amounts of an acid component and a glycol component are as follows. Acid component: phthalic acid / fumaric acid = 4/6 (molar ratio), glycol component: 1,4-butanediol / other glycol = 10/0 (molar ratio).
Moreover, the crushability in a Henschel mixer was good, and there was no stickiness and blocking of the crushed material.

<Compound creation procedure>
[Example 1]
The unsaturated polyester alkyd (A) and triallyl isocyanurate (B1) as the allylic copolymerizable monomer (B) are mixed at a blending ratio of B1 / (A + B1) of 10 wt%, 20 wt%, 25 wt% or It mix | blended so that it might become 30 wt%, it melt-kneaded at 90-100 degreeC, and was set as the unsaturated polyester resin. As a polymerization initiator, 1 part by mass of dicumyl peroxide was added to 100 parts by mass of the obtained unsaturated polyester resin, and the mixture was melt-kneaded at 90 to 100 ° C. to prepare a thermosetting resin composition.
Next, the rare earth-iron-based magnet flakes and the thermosetting resin composition produced as described above are melt-kneaded using an 8-inch mixing roll having a surface temperature set to 100 ° C. without solvent. A melt-kneaded product was obtained. Here, the rare earth-iron-based magnet flakes and the thermosetting resin composition were blended so that the ratio of the thermosetting resin composition was 3.0 wt% with respect to the rare-earth-iron-based magnet flakes. Subsequently, the melt-kneaded product was adjusted to a thickness of 1 mm or less using a constant speed roll mill having a surface temperature of 80 ° C., and coarsely pulverized with a Henschel mixer. Thereafter, the particles were classified into particles having a particle size of 53 to 500 μm by crushing with an electric mortar and sieving to obtain a rare earth-iron bond magnet compound used in Example 1.
Sample 1: B1 / (A + B1) = 10 wt%, ratio of thermosetting resin composition: 3.0 wt%
Sample 2: B1 / (A + B1) = 20 wt%, ratio of thermosetting resin composition: 3.0 wt%
Sample 3: B1 / (A + B1) = 25 wt%, ratio of thermosetting resin composition: 3.0 wt%
Sample 4: B1 / (A + B1) = 30 wt%, ratio of thermosetting resin composition: 3.0 wt%

[Example 2]
The unsaturated polyester alkyd (A) and the trimethallyl isocyanurate (B2) as the allylic copolymerizable monomer (B), the blending ratio: B2 / (A + B2) is 10 wt%, 20 wt% or 30 wt% It mix | blended so that it might become, and was melt-kneaded at 90-100 degreeC, and was set as the unsaturated polyester resin. As a polymerization initiator, 1 part by mass of dicumyl peroxide was added to 100 parts by mass of the obtained unsaturated polyester resin, and the mixture was melt-kneaded at 90 to 100 ° C. to prepare a thermosetting resin composition.
Next, the rare earth-iron-based magnet flakes and the thermosetting resin composition produced as described above are melt-kneaded using an 8-inch mixing roll having a surface temperature set to 100 ° C. without solvent. A melt-kneaded product was obtained. Here, the rare earth-iron-based magnet flakes and the thermosetting resin composition were blended so that the ratio of the thermosetting resin composition was 3.0 wt% with respect to the rare-earth-iron-based magnet flakes. Subsequently, the melt-kneaded product was adjusted to a thickness of 1 mm or less using a constant speed roll mill having a surface temperature of 80 ° C., and coarsely pulverized with a Henschel mixer. Thereafter, the particles were classified to 53 to 500 μm by crushing with an electric stone mill and sieving to obtain a rare earth-iron-based bond magnet compound used in Example 2.
Sample 5: B2 / (A + B2) = 10 wt%, ratio of thermosetting resin composition: 3.0 wt%
Sample 6: B2 / (A + B2) = 20 wt%, ratio of thermosetting resin composition: 3.0 wt%
Sample 7: B2 / (A + B2) = 30 wt%, ratio of thermosetting resin composition: 3.0 wt%

Example 3
The unsaturated polyester alkyd (A) and triallyl isocyanurate (B1) as the allylic copolymerizable monomer (B) are blended so that the blending ratio B1 / (A + B1) is 25 wt%. It melt-kneaded at 90-100 degreeC, and was set as the unsaturated polyester resin. As a polymerization initiator, 1 part by mass of dicumyl peroxide was added to 100 parts by mass of the obtained unsaturated polyester resin, and the mixture was melt-kneaded at 90 to 100 ° C. to prepare a thermosetting resin composition.
Next, the rare earth-iron-based magnet flakes and the thermosetting resin composition produced as described above are melt-kneaded using an 8-inch mixing roll having a surface temperature set to 100 ° C. without solvent. A melt-kneaded product was obtained. Here, the ratio of the thermosetting resin composition is 2.5 wt%, 3.0 wt%, 3.5 wt%, or 4.0 wt% with respect to the rare earth-iron magnet flakes. A system magnet flake and a thermosetting resin composition were blended. Subsequently, the melt-kneaded product was adjusted to a thickness of 1 mm or less using a constant speed roll mill having a surface temperature of 80 ° C., and coarsely pulverized with a Henschel mixer. Thereafter, the particles were classified into particles having a particle size of 53 to 500 μm by crushing with an electric stone mill and sieving to obtain a rare earth-iron-based bonded magnet compound used in Example 3.
Sample 8: Ratio of thermosetting resin composition: 2.5 wt%, B1 / (A + B1) = 25 wt%
Sample 9: Ratio of thermosetting resin composition: 3.0 wt%, B1 / (A + B1) = 25 wt%
Sample 10: Ratio of thermosetting resin composition: 3.5 wt%, B1 / (A + B1) = 25 wt% (same composition as Sample 3 above)
Sample 11: Ratio of thermosetting resin composition: 4.0 wt%, B1 / (A + B1) = 25 wt%

[Comparative Example 1]
As the thermosetting resin composition used in the comparative example, a bisphenol A novolac type epoxy resin and a bisphenol A type phenol curing agent were used. A solid bisphenol A novolak type epoxy resin and a bisphenol A type phenol curing agent are dissolved in methyl ethyl ketone to form a dissolved product. Volatilization gave a mixture. The mixture was pulverized with an electric stone mill and then classified to 355 μm or less with a sieve to obtain a rare earth-iron-based bonded magnet compound used in Comparative Example 1.
Here, the rare earth-iron-based magnet flakes and the thermosetting resin composition were blended so that the ratio of the thermosetting resin composition was 2.5 wt% with respect to the rare-earth-iron-based magnet flakes.

[Create compression molding]
Each rare earth-iron-based magnet compound of Example 1 (Samples 1 to 4), Example 2 (Samples 5 to 7), Example 3 (Samples 8 to 11) and Comparative Example 1 was formed into a mold having an inner diameter of φ10 mm. 3.3 g was filled and compression molded to a length of about 7 mm at a molding pressure of 0.6 MPa, 0.8 MPa, 1.0 MPa, or 1.2 MPa, and Example 1, Example 2, Example 3 and Comparative Example 1 A compression molded body (columnar shape) was obtained. The outer diameter dimension and length dimension of each compression molding obtained were measured with a micrometer, the mass was measured with an electronic balance, and the density (Mg / m ³ ) was calculated.

[Preparation of rare earth-iron bond magnet (thermosetting of thermosetting resin)]
The obtained compression molded body was taken out of the mold and heated in a 200 ° C. atmosphere for 15 minutes to cure the thermosetting resin, and the rare earth-irons of Example 1, Example 2, Example 3 and Comparative Example 1 were used. A bonded magnet was obtained. The outer diameter dimension and length dimension of each obtained rare earth-iron-based bonded magnet were measured with a micrometer, the mass was measured with an electronic balance, and the density (Mg / m ³ ) was calculated.

[Density change]
For each example or comparative example and molding pressure, the density increase / decrease rate (%) is as follows using the density before thermosetting (compression molding) and the density after thermosetting (rare earth-iron bond magnet). This was calculated using the following formula.
Density increase / decrease rate (%) = [(density after thermosetting−density before thermosetting) / density before thermosetting] × 100
Based on the obtained results, FIGS. 1 to 3 are diagrams showing density changes before and after thermosetting with respect to the density of the compression molded body before thermosetting.

As shown in FIG. 1, when the ratio of the thermosetting resin composition is 3.0 wt% with respect to the rare earth-iron magnet flakes, unsaturated polyester alkyd (A) and triallyl isocyanate (B1) ) When the blend of triallyl isocyanurate (B1) with respect to the total mass of 25) is 25 wt% (sample 3) or 30 wt% (sample 4), the density increase / decrease rate (%) before and after thermosetting is any molding performed this time. The pressure was also positive, and the result was that the density increased by thermosetting.

As shown in FIG. 2, when trimethallyl isocyanate (B2) is used as the allylic copolymerizable monomer (B), the composition of triallyl isocyanurate (B2): thermosetting at 30 wt% (sample 7) The density increase / decrease rate (%) before and after became positive at any of the molding pressures carried out this time, and the result was that the density increased by thermosetting.
When the content of trimethallyl isocyanurate (B1) is 20% (sample 6), the density of the compression molded body is approximately 5.85 Mg / m ³ or more, and the result is that the density starts to increase due to thermal curing. It was.

  Further, as shown in FIG. 3, the ratio of the thermosetting resin composition is 3.0 wt% (sample 9), 3.5 wt% (sample 10), 4.0 wt% (sample) with respect to the rare earth-iron-based magnet flakes. 11) When it mix | blends so that it may become, in any pressure implemented this time, the result that a density increases by thermosetting was obtained.

[Example 4]
Next, the volume fraction of residual voids (also referred to as void ratio) of each sample was calculated for Sample 3, Sample 4, Sample 6, and Sample 7 that resulted in an increase in density due to thermosetting. The density change after thermosetting with respect to the porosity (%) of the compression molded product is shown in FIG.
The volume fraction of residual voids was calculated from the following formula.
Volume fraction of residual void = 100−volume fraction of magnet powder−volume fraction of thermosetting resin Here, the volume fraction of magnet powder and the volume fraction of thermosetting resin are rare earths relative to the mass of each sample. The mixing ratio of each of the iron-based magnet flakes and the thermosetting resin composition, the true density value of the rare earth-iron-based magnet flakes (7.59 Mg / m ³ ), and the true density value of the thermosetting resin composition by the Archimedes method (1.25 Mg / m ³ : Sample 3, Sample 4) (1.26 Mg / m ³ : Sample 6, Sample 7)

  As shown in FIG. 4, the result of increasing the density by thermosetting when the porosity is in the range of 6 vol% to 12 vol% was obtained.

Claims (8)

A rare earth-iron-based magnet compound containing a rare earth-iron-based magnet flake and a thermosetting resin composition is prepared, the compound is compression-molded to form a compression-molded body, and the compression-molded body is heat-cured to form a rare earth- An iron-based bond magnet,
By the heat curing of the compression molded body, the density is higher than that of the compression molded body before the heat curing,
Rare earth-iron bond magnet. The rare earth-iron bond magnet according to claim 1, wherein the thermosetting resin composition is included in an amount of 3 wt% to 4 wt% with respect to the rare earth-iron magnet flakes. The rare earth-iron system according to claim 1 or 2, wherein the thermosetting resin composition includes an unsaturated polyester alkyd, an allylic copolymerizable monomer, and an organic peroxide. Bond magnet. The thermosetting resin composition contains the unsaturated polyester alkyd (A) and the allylic copolymerizable monomer (B) in a mass ratio of 30 wt% ≧ B / (A + B) ≧ 20 wt%. The rare earth-iron-based bonded magnet according to claim 3, characterized in that it is characterized in that The thermosetting resin composition contains the unsaturated polyester alkyd (A) and the allylic copolymerizable monomer (B) in a mass ratio of 30 wt% ≧ B / (A + B) ≧ 25 wt%. The rare earth-iron bond magnet according to claim 3, wherein The unsaturated polyester alkyd is any one of a terephthalic acid unsaturated polyester resin and an isophthalic acid unsaturated polyester resin, according to any one of claims 3 to 5. Rare earth-iron bond magnet. The rare earth element according to any one of claims 3 to 5, wherein the allylic copolymerizable monomer is either one of triallyl isocyanurate or trimethallyl isocyanurate. Iron-based bond magnet. The rare earth-iron bond magnet according to any one of claims 1 to 7, wherein the compression molded body includes residual voids at a volume fraction of 6 vol% or more and 12 vol% or less.

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