JP2000173810A - Magnetic anisotropic bond magnet and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve orientation by a method wherein slurry composed of rare earth/ iron/nitrogen based magnet material powder, liquid state thermosetting resin and organic solvent is wet-molded in magnetic field by a compression molding method, and the molded member is held at a temperature higher than or equal to a boiling point of organic solvent and lower than a curing start temperature of liquid state thermosetting resin, subjected to desolvation and heated and cured. SOLUTION: In a magnetic anisotropic bond magnet, nitride magnet powder as magnet powder wherein mean powder grain diameter is about 15 μm, powder grain diameter distribution is 0.5-30 μm, composition of at.% is Sm9.1Fe77.3N13.6 is pulverized to fine powder wherein powder grain diameter distribution is in a range of 0.5-30 μm and mean powder grain diameter is 1.9 μm, with a jet mill and by wet ball mill crushing. Liquid state epoxy resin of 2.6 wt.%, hardener of 2.6 wt.% and methyl ethyl ketone of 2.6 wt.% are mixed with the magnet fine powder of 100 wt.%. Stirring and kneading are performed, and a slurry state is obtained. After this slurry is wet compression-molded in magnetic field, the molded member is heated for one hour at 85 deg.C, and subjected to desolvation and further to thermosetting treatment for two hours at 170 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth / iron / nitrogen based magnetically anisotropic bonded magnet having greatly improved magnetic field orientation and a method of manufacturing the same.

[0002]

2. Description of the Related Art The mainstream of magnetic powder frequently used in rare-earth bonded magnets is a magnetic isotropic magnetic powder having an Nd ₂ Fe ₁₄ B type intermetallic compound as a main phase. This magnetic isotropic magnet powder is prepared by melting a raw material alloy containing Nd, Fe, and B as main components and having a predetermined composition, then rapidly quenching by a molten metal quenching method to produce an amorphous alloy, and then performing heat treatment at an appropriate temperature. Thereby, the average crystal grain size is set to 0.01 to 0.5 μm. In addition, as a magnetic anisotropic magnet powder having a Nd ₂ Fe ₁₄ B type intermetallic compound as a main phase, a raw material alloy blended with the above-mentioned predetermined composition is melted and cast by a strip casting method, a high frequency melting method, or the like, and a predetermined amount is cast. There is a magnetic anisotropic magnet powder obtained by obtaining an alloy having a composition and a grain size, then pulverizing the alloy to an appropriate size, and then refining the crystal while giving anisotropy by a so-called HDDR method. Alternatively, there is a magnet powder that is anisotropically imparted by subjecting a thin piece of the amorphous alloy to hot pressing or the like and then hot-pressing and densifying it, and then performing plastic working such as upsetting in the warm state. .

[0003] With the recent downsizing of rare earth bonded magnet applied products, rare earth bonded magnets used for such products are necessarily required to have smaller dimensions and higher magnetic properties. For example, a CD-ROM for a spindle motor that constitutes a hard disk of a computer
Downsizing for motors of drive units and for rotating equipment such as DVDs (digital video discs) in the future.
There is an extremely strong demand for higher performance, and there is a strong demand for a rare earth bonded magnet that can satisfy this demand. The rare-earth bonded magnets for rotating equipment are mainly ring-shaped, and are subjected to specific magnetization depending on the application and mounted on a predetermined magnetic circuit.

A rare-earth bonded magnet containing a magnetic isotropic rare-earth magnet powder containing a Nd ₂ Fe ₁₄ B-type intermetallic compound as a main phase is easy to mold and has a high degree of freedom in magnetization, so that it is generally easy to use. Are better. However, since magnetic anisotropy is not provided, the magnet-applied products often do not meet the requirements for miniaturization and high performance.

As a candidate satisfying the requirements for downsizing and high performance of the magnet application products, a magnetic anisotropic rare earth magnet powder containing the above-mentioned Nd ₂ Fe ₁₄ B type intermetallic compound as a main phase is blended. Although there is an anisotropic bonded magnet, it has the following problems. First, in a molding step in a magnetic field for imparting magnetic anisotropy, for example, 30 to 50 kOe is required to sufficiently orient magnetic anisotropic magnet powder having Nd ₂ Fe ₁₄ B type intermetallic compound as a main phase. A very strong applied magnetic field strength (alignment magnetic field strength) is required. However, rare earth bonded magnets used in practical use have various various shapes such as a simple block shape, a ring shape, an arc segment shape, and a tortoise shape. In addition to these various rare-earth bonded magnets,
Various magnetic anisotropies suitable for practical use, such as polar anisotropy and radial anisotropy, are provided according to the respective applications. But,
In order to impart these various magnetic anisotropies, 30 to 50
Ensuring a very high applied magnetic field strength of kOe involves difficulties in industrial production. For example, when manufacturing a ring-shaped radial anisotropic rare earth bonded magnet, an applied magnetic field is passed in the radial (outer diameter) direction from a ferromagnetic core provided on the inner diameter side of a cavity of a molding die corresponding to the ring shape of the molded body. Although it is necessary, the cross-sectional area of the ferromagnetic core on the inner diameter side, which plays a part of the magnetic circuit for generating the applied magnetic field, cannot be increased due to restrictions on the mold structure. The magnetic core is magnetically saturated, resulting in 3
It is difficult to obtain a high applied magnetic field strength of 0 to 50 kOe. Therefore, Nd _{2 in} the compound
There is a problem that a sufficient applied magnetic field strength for arranging the rare earth magnet powder having the Fe ₁₄ B type intermetallic compound as a main phase in the radial direction cannot be obtained. The problem of insufficient applied magnetic field strength is a general problem as well as a polar magnet with an anisotropic ring shape or a segment magnet having radial or polar anisotropy. Further, there is a problem that bond magnets having insufficient orientation (defective) due to insufficient applied magnetic field strength are difficult to demagnetize after being magnetized. In order to improve the magnetic field orientation,
JP-A-9-199363 discloses a molding method in which a heated mold is filled with a mixture substantially consisting of a rare earth magnet powder having magnetic anisotropy and a thermosetting resin, and a maximum magnetic field is applied when the resin liquefies. is suggesting. According to this proposal, it is reported that the coercive force of the rare earth magnet powder is reduced, the magnetic field orientation is improved, and magnetic properties close to the original potential of the rare earth magnet powder are obtained. However, this proposal has a problem that in addition to the complexity of heating the mold, it takes time to liquefy the binder resin and the molding tact time is inferior.

In recent years, researches on rare earth / iron / nitrogen magnet powders have been conducted as rare earth magnet powders for bond magnets which replace the above-mentioned conventional Nd-Fe-B magnet powders. This magnet powder has a magnetization mechanism belonging to a nucleation type and has an average particle size of several μm. Molding raw material (compound) obtained by binding this rare earth / iron / nitrogen magnet powder with resin
The anisotropic bonded magnet can be obtained by performing injection molding in a magnetic field at, for example, 180 to 250 ° C. In this case, the coercive force of the rare-earth / iron / nitrogen-based magnet powder in the compound is reduced by heating as in the proposal of JP-A-9-199363, and the ratio of the binder resin is large, so that the compound has relatively good orientation. Things are obtained. However, in the case of injection molding in a magnetic field, about 20 to 50% by volume of resin is added to secure the fluidity of the compound, so that the filling ratio of rare earth / iron / nitrogen based magnet powder becomes relatively low. It is difficult to obtain a higher performance anisotropic bonded magnet.

Next, an anisotropic bonded magnet is produced by a conventional compression molding method in a magnetic field using a compound having a higher filling ratio of rare earth / iron / nitrogen magnet powder than the compound for injection molding in a magnetic field. In this case, good orientation cannot be provided with a practical orientation magnetic field strength of about 3 to 10 kOe,
There is a problem that a rare-earth bonded magnet having high magnetic properties cannot be obtained. In this regard, as a result of a detailed investigation by the present inventors, the following findings were obtained. Conventionally kneading using a twin-screw kneader heated to an appropriate temperature to obtain the compound,
It is difficult to evenly cover the surface of a rare earth / iron / nitrogen magnet powder having a large specific surface area (small powder particle size) with a binder resin, and this tendency is due to the rare earth / iron / nitrogen magnets for the binder resin. This is remarkable in compression molding compounds having a high powder ratio. When the conventional compression molding is performed under the above-mentioned practical orientation magnetic field strength, in addition to the deterioration factor of the magnetic field orientation due to the high viscosity of the binder resin, the rare-earth / iron / nitrogen-based material not covered with the binder resin is used. The mutual contact between the magnet powders becomes remarkable, and the orientation of the finally obtained bonded magnet is greatly reduced.

[0008]

Accordingly, an object of the present invention is to provide good anisotropy even at a practically low intensity of the orientation magnetic field, and achieve a higher residual magnetic flux density (Br) and a higher maximum energy product (( Rare earth, iron,
An object of the present invention is to provide a nitrogen-based magnetic anisotropic bonded magnet and a method for manufacturing the same.

[0009]

According to the present invention, which solves the above-mentioned problems, a rare-earth / iron / nitrogen-based magnet material powder exhibiting magnetic anisotropy is cured by using a liquid thermosetting resin and a curing start temperature of the liquid thermosetting resin. Into a mixed solution comprising an organic solvent having a lower boiling point than to form a slurry, and using the slurry at a temperature lower than the boiling point of the organic solvent (for example, room temperature) by a compression molding method in a wet magnetic field, The obtained molded body is kept at a temperature equal to or higher than the boiling point of the organic solvent and less than the curing start temperature of the liquid thermosetting resin, and after desolvation, is heated and cured, and if necessary, is subjected to coining or sizing to obtain a molded body density. This is a method for producing a magnetically anisotropic bonded magnet that enhances. In order to cover the surface of rare earth / iron / nitrogen based magnet material powder with magnetic anisotropy with liquid thermosetting resin almost uniformly,
It is preferable to form a slurry by stirring.

[0010] Liquid thermosetting resins have a high viscosity at room temperature, but when diluted with an organic solvent, have many useful effects. Since the viscosity of the liquid mixture composed of the liquid thermosetting resin and the organic solvent decreases due to the contribution of the organic solvent, the liquid mixture can almost completely cover the surface of the magnet powder. At the same time, the mixed solution penetrates into the inside, and finally the binding effect can be enhanced. Further, for example, since a slurry can be formed at room temperature by using a simple stirring device without heating, kneading equipment cost can be reduced, and kneading (resin coating) can be easily performed. A particularly useful effect is that by forming the slurry, in the wet compaction process in a magnetic field, the magnetic field orientation deterioration factors such as the direct contact between the magnet powders and the constraint due to the high viscosity of the binder resin can be greatly reduced. As described above, since the surfaces of the individual magnet powder particles are almost uniformly coated with the resin and are in a low-viscosity slurry state, the individual magnet powder particles can be favorably formed at room temperature with a low orientation magnetic field strength of 3 to 10 kOe. Can be oriented. Therefore, a rare earth / iron / nitrogen based magnetically anisotropic bonded magnet having higher Br and higher (BH) max than before can be obtained. Further, in the compression molding process in a wet magnetic field, the mixed solution oozes out of the molded body in the middle of molding, so that it has a kind of lubricating effect and can improve mold galling. The organic solvent is selected to have a rust-preventing action in order to prevent oxidation of the rare earth / iron / nitrogen based magnetic material powder.
Since the organic solvent remains inside the molded body, the solvent is removed at a temperature equal to or higher than the boiling point of the organic solvent and lower than the curing start temperature of the liquid thermosetting resin. After desolvation, since the organic solvent escapes, it substantially consists of the above-mentioned magnet powder and epoxy resin.
Subsequently, a magnetic anisotropic bonded magnet of the present invention can be obtained by performing a heat curing treatment. Heating conditions under which the solvent removal and the heat curing can be performed simultaneously may be selected. Alternatively, a higher Br and (B
H) A magnetically anisotropic bonded magnet having max is obtained. The coining or sizing treatment is performed by introducing the desolvation treatment into the cavity of the compression molding die having no magnetic field, and applying a pressure higher than the pressure of the compression molding in the wet magnetic field once or twice or more, This is a step of increasing the density by adding a short time (usually 1 second or less). The voids after the organic solvent has escaped by coining or sizing can be filled to some extent, but they cannot be completely eliminated. Therefore, the magnetic anisotropic bonded magnet obtained by the present invention has a high Br
And has a high (BH) max and necessarily has a porosity of 5 to 22% by volume.

The rare earth / iron / nitrogen based magnetic material powder exhibiting the magnetic anisotropy is R _α T _100-α-β N _β , wherein R is one or more of rare earth elements including Y. T necessarily contains Sm, T is Fe or Fe and Co), and α and β are atomic percentages, each having a composition represented by 5 ≦ α ≦ 20 and 5 ≦ β ≦ 30. As the magnet powder, for example, Th
₂ Zn ₁₇ type, Th ₂ Ni ₁₇ type, Sm-T-N magnet alloy powder either to the magnet main phase of crystal structure of the TbCu ₇ (T is Fe or Fe and Co) be used it can. Preferably, the R content is between 5 and 20% in atomic percent. If it is less than 5%, the coercive force is greatly reduced. 20
%, The saturation magnetization decreases and Br decreases significantly. It is permissible for R to contain one or more rare earth elements including Y inevitably. However, in order to secure a coercive force (iHc) of 5 KOe or more, R
The ratio is 50% or more in atomic percentage, more preferably 90%.
As described above, it is ideal that R = Sm except for inevitable impurities. Nitrogen is preferably from 5 to 30% by atomic percentage. If it is less than 5%, the magnetic anisotropy becomes small, and the coercive force is greatly reduced. When it exceeds 30%, magnetic anisotropy,
Since the saturation magnetization is small, a practical magnet material cannot be formed. In the present invention, some of Sm and Fe are replaced with Co, Ni, Ti, Cr, Mn, Zn, Cu, Zr,
Nb, Mo, Ta, W, Ru, Rh, Hf, Re, Os
Or Ir. The amount of these additives is Co
Except for about 10 atomic% or less based on the total amount of Sm and Fe. If it is more than this, the saturation magnetization becomes small, which is not preferable. In the case of Co substitution, the decrease in saturation magnetization is small, and substitution is possible in the range of 0.1 to 70 atomic% with respect to the Fe amount, and an effect of increasing the Curie temperature is obtained.
It is also possible to partially replace N with C, P, Si, S, Al, or the like. The addition amount is about 1 to the N content.
It is not more than 0 atomic%, and an addition amount larger than this is not preferable because the coercive force decreases.

In the present invention, the liquid thermosetting resin is an epoxy resin, and the organic solvent has a boiling point of 130 ° C.
It is practical to use less than a ketone. Although the present invention can be constituted by a powdery epoxy resin, a liquid thermosetting resin can produce a mixed solution in a much shorter time in consideration of solubility in an organic solvent. As a suitable organic solvent soluble in the liquid epoxy resin, one or more of ketones called polar solvents such as acetone, methyl ethyl ketone and butyl ethyl ketone are desirable. The reason is that there is little evaporation around room temperature and a boiling point exists near the curing start temperature of the binder resin. Since there are various types of liquid thermosetting epoxy resins depending on the use environment, the curing start temperature cannot be determined steadily.
Those having a curing start temperature of 40 ° C. are preferred.

In the present invention, the particle size distribution is 0.5 to 30 μm.
m, and and _{R α T 100-α- β N} β, (R always includes one or two or more kinds Sm of rare earth elements including Y, T is Fe or Fe and Co), α, β Is a magnetic field substantially consisting of a magnetically anisotropic rare-earth / iron / nitrogen-based magnet material powder having a composition represented by 5 ≦ α ≦ 20 and 5 ≦ β ≦ 30 in atomic percentage and a thermosetting resin. An isotropic bonded magnet having a porosity of 5 to 22% and a porosity of 20 to 20%.
Maximum energy product of 10 MGOe or more at (° C) ((B
H) max) high performance magnetic anisotropic bonded magnet. The magnetic anisotropic bonded magnet of the present invention is manufactured by using a compression molding method in a wet magnetic field.

In the present invention, pulverization is performed to prepare a mother alloy powder to be subjected to the nitriding treatment or to pulverize the powder after the nitriding treatment. This pulverization can be efficiently performed by a hammer mill, a disk mill, a vibration mill, an attritor, a jet mill or the like maintained in an inert gas atmosphere. continue,
A high saturation magnetization and a high anisotropic magnetic field are imparted by subjecting the pulverized master alloy powder for nitriding to a nitriding treatment. In the nitriding treatment, the master alloy powder for nitriding is mixed with a nitrogen gas, a mixed gas of nitrogen and hydrogen, an ammonia gas, or a reducing mixed gas containing ammonia (for example, a mixed gas of ammonia and hydrogen, a mixed gas of ammonia and nitrogen, and a mixed gas of ammonia and ammonia). Argon mixed gas) atmosphere (in the air stream)
This is performed by heating and holding at 300 to 650 ° C. × 0.1 to 30 hours. 300 ° C x less than 0.1 hour and 650 ° C
If it exceeds 30 hours, it is difficult to obtain the one having the above-mentioned optimum nitrogen content. The master alloy powder for nitriding contains hydrogen inevitably irrespective of the presence or absence of nitriding treatment. However, when exposed to a nitriding gas containing hydrogen, the final
Contains 0 atomic% hydrogen. It is preferable that the powder particle size distribution is 0.5 to 30 μm so that the mother alloy powder for nitriding is nitrided to the core. If the thickness exceeds 30 μm, the core that is not nitrided increases, and the magnetic properties deteriorate. If the thickness is less than 0.5 μm, the oxidation is remarkable, and the magnetic characteristics are deteriorated. After that, nitriding, grinding, slurrying, compression molding in a wet magnetic field, desolvation,
Heat curing and, if necessary, coining (sizing) are performed sequentially. In the present invention, 0.5% by weight of a known surface modifier such as a silane-based or titanium-based coupling agent is previously added to the magnet powder or the liquid thermosetting resin to be slurried.
The following addition is preferable for improving the binding strength and the magnetic properties. If the surface modifier is added in an amount exceeding 0.5 wt%, the magnetic properties deteriorate.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

First, a description will be given of good orientation at a low orientation magnetic field strength realized by slurrying. (Example 1) The average powder particle diameter is about 15 μm as a magnet powder.
The powder particle size distribution is 0.5 to 30 μm and at%
A nitrided magnet powder having a composition of Sm _9.1 Fe _77.3 N _13.6 was prepared. Subsequently, the powder is finely pulverized by a jet mill to an average powder particle size of 4.0 μm, and further finely pulverized by wet ball mill pulverization using hexane, and the powder particle size distribution is in the range of 0.5 to 30 μm and the average powder is A fine powder having a particle size of 1.9 μm was obtained. The reason for combining jet mill pulverization and wet ball mill pulverization is that jet mill pulverization can provide fine powder having a sharp particle size distribution in the range of 0.5 to 30 μm, but reducing the average powder particle size to less than 4 μm is industrial. With production difficulties. Also, only by wet ball mill pulverization, very fine submicron fine particles of less than 0.5 μm are often generated. 2.6 parts by weight of the liquid epoxy resin and 2.
6 parts by weight of a curing agent (DDS: diaminodiphenylsulfone) and, as an organic solvent, the same weight (2.6 parts by weight) of a liquid epoxy resin as methyl ethyl ketone (boiling point 79.
5 ° C.). In the stirring and kneading, a liquid mixture of the liquid epoxy resin, DDS and methyl ethyl ketone adjusted to the respective weight ratios described above was prepared in advance, and then the magnet powder was added, and the mixture was stirred for 20 minutes to form a slurry. Using this slurry, an orientation magnetic field strength of 5, 10 kOe, 6 ton / cm ²
Compression molding in a wet magnetic field at a molding pressure of The obtained molded body was heated and held at 85 ° C. for 1 hour to remove the solvent, and then heat-cured at 170 ° C. for 2 hours to obtain a magnetic anisotropic bonded magnet of the present invention. Table 1 shows the results of evaluating the density, porosity, and magnetic properties of the obtained bonded magnet. Magnetic properties were measured at 20 ° C. The porosity was defined by the following equation.

[0017]

Porosity = (theoretical density−actual density) / (theoretical density) × 100 (%)

[0018]

[Table 1]

Example 2 A bonded magnet of the present invention was prepared and evaluated in the same manner as in Example 1 except that the orientation magnetic field strength was changed to 10 kOe. Table 1 shows the results of the evaluation. (Comparative Examples 1 and 2) Using the same magnet powder as in Example 1,
As described below, a magnetic anisotropic bonded magnet of a comparative example was prepared by a dry compression molding method in a magnetic field using a compound obtained under conventional kneading conditions, and evaluated. The magnet powder 1
2.6 parts by weight of a liquid epoxy resin and 2.6 parts by weight of a curing agent (DDS) were mixed and mixed with 00 parts by weight, and then heated and kneaded by a biaxial kneader. Since the pellets of the kneaded material by this twin-screw kneader are rich in viscosity, the
After heat treatment at 1 ° C. for 1 hour, the mixture was pulverized into a compound. Next, the orientation magnetic field strength is 5, 10 kOe, 6 ton /
Compression molding was performed in a dry magnetic field at a molding pressure of cm ² . After molding,
A heat hardening treatment was performed at 170 ° C. for 2 hours to obtain a bonded magnet of a comparative example. Thereafter, the results of evaluation in the same manner as in Example 1 are shown in Table 1. (Comparative Example 3) MQP-B material (MQP-B) manufactured by US MQI (Magnequench International) as a magnet powder
Slurry, wet compression molding, desolvation, and heat curing were performed in the same manner as in Example 1 except that the material was an Nd-Fe-B-based isotropic magnet powder produced by a melt quenching method. A bonded magnet of a comparative example was obtained. The wet compression molding was performed without a magnetic field. Table 1 shows the evaluation results of the obtained bonded magnets.
Shown in (Comparative Example 4) MQP-B material (MQP-B) manufactured by US MQI (Magnequench International), Inc. as a magnet powder
Kneading with a twin-screw kneader, compounding, dry compression molding in the same manner as in Comparative Example 1 except that the material is an Nd—Fe—B-based isotropic magnet powder produced by a melt quenching method. Heat curing was performed to obtain a bonded magnet of a comparative example. The dry compression molding was performed without a magnetic field. Table 1 shows the evaluation results of the obtained bonded magnets. (Comparative Examples 5 and 6) MQA-T material (MQA-MQ) manufactured by US MQI (Magnequench International), Inc. as a magnet powder
-T material is an Nd-Fe-B-based anisotropic magnet powder produced by an HDDR method), except that a slurry was formed in the same manner as in Example 1 or Example 2, and wet compression was performed in a magnetic field. Molding, solvent removal, and heat curing were performed to obtain a bonded magnet of a comparative example. Table 1 shows the evaluation results of the obtained bonded magnets. (Comparative Examples 7 and 8) MQA-T material (MQA) manufactured by US MQI (Magnequench International), Inc. as a magnet powder
-T material is an Nd-Fe-B-based anisotropic magnet powder produced by the HDDR method), except that kneading and compounding with a twin-screw kneader were performed in the same manner as in Comparative Example 1 or Comparative Example 2. The resultant was subjected to compression molding in a dry magnetic field and heat curing to obtain a bonded magnet of a comparative example. Table 1 shows the evaluation results of the obtained bonded magnets. From Table 1, it can be seen that Examples 1 and 2 have higher Br and higher (BH) ma than those of Comparative Examples 1 to 8.
It can be seen that it has x and has a large porosity exceeding 15%. In this way, a slurry having a high Br and (BH) max of 12 MGOe or more was obtained at a low orientation magnetic field strength of 5 to 10 kOe by slurrying. Further, from a related study, a high Br of 10 MGOe or more at a low orientation magnetic field strength of 3 kOe or more,
It was confirmed that (BH) max was obtained.

Example 3 A compact was obtained by performing compression molding in a wet magnetic field in the same manner as in Example 1 except that the pressing force in the wet magnetic field compression molding was set to 3 ton / cm ² . Next, the molded body was desolvated at 80 ° C. for 1 hour, and then subjected to a heat treatment at 120 ° C. for 1 hour to slightly cure the binder resin. Next, the effect of performing a coining (sizing) process on the bonded magnet sample will be described below. As a coining process, any one of the bonded magnet samples is put into a mold cavity of a dry compression molding machine having no magnetic field, and then 4 to 10 ton / c.
Each time, a pressure of about 0.3 seconds was applied once in a molding pressure range of m ² to increase the density. Coining treatment (densification) in each of the above pressure ranges was heated and cured at 170 ° C. for 2 hours to obtain a bonded magnet of the present invention. FIG. 1 shows an example of the correlation between the pressure of the coining, the porosity, and the maximum energy product. FIG. 1 shows that the porosity can be effectively reduced (the maximum energy product can be improved) by coining. However, considering the occurrence of breakage of the molding die, etc.
Coining exceeding ton / cm ² is not preferable for industrial production. When the porosity exceeds 22%, the following Comparative Example 9
, The significant difference from the maximum energy product of the Nd—Fe—B-based bonded magnet almost disappears. Therefore, the porosity is 5 to 22%,
More preferably 5 to 20%, particularly preferably 5 to 10%
Is good. (Comparative Example 9) The pressing force of compression molding in a wet magnetic field was 3 ton /
Compression molding was performed in a wet magnetic field in the same manner as in Comparative Example 5 except that the pressure was set to cm ² to obtain a molded body. Next, the molded body was heated at 80 ° C. for 1 hour.
After removing the solvent for one hour, a heat treatment was further performed at 120 ° C. for one hour to slightly cure the binder resin. Next, the result of subjecting the bonded magnet sample to a coining (sizing) treatment under the same conditions as in Example 3 is shown in FIG. As shown in FIG. 1, a lower (BH) max was obtained than in Example 3.

(Embodiment 4) Using the slurry prepared in Embodiment 1, a cavity having an outer diameter of 25 mm and an inner diameter (core outer diameter) of 22 mm can be provided with symmetrical 8-pole polar anisotropy. Molding in a wet magnetic field at a molding pressure of 3 ton / cm ² by a compression molding machine equipped with a magnetic anisotropic mold with a magnetic field coil (the orientation magnetic field strength in the direction of imparting polar anisotropy is about 5 kOe).
A polar anisotropic symmetrical 8-pole ring-shaped bonded magnet molded body (outside diameter 25 mm, inside diameter 22 mm, thickness 1.5 mm) was obtained. After the molded body was heated to an appropriate temperature to remove the solvent, it was coined at a pressure of 8 ton / cm ² using a compression molding machine with no magnetic field, and then heated and cured to obtain a polar anisotropic bonded magnet according to the present invention. . The porosity of this bonded magnet was in the range of 5 to 22%. Next, the magnetization of the bonded magnet along the direction of imparting polar anisotropy (magnetizing magnetic field strength: about 5 kOe) was performed, and the result of measuring the surface magnetic flux density is shown in FIG. 2, the surface magnetic flux density of the symmetric octupole-pole anisotropic ring bond magnet of the present invention is a very high value of 2600-2650G. (Example 5) A magnetic anisotropic mold with a magnetic field coil having a cavity having an outer diameter of 25 mm and an inner diameter (core outer diameter) of 22 mm and capable of imparting radial anisotropy using the slurry prepared in Example 1. (The orientation magnetic field strength in the direction of imparting radial anisotropy is about 5 kOe.) Molding is performed in a wet magnetic field at a molding pressure of 3 ton / cm ² with a compression molding machine installed, and a radially anisotropic ring-shaped bonded magnet molded product (outer diameter 25 mm, an inner diameter of 22 mm, and a thickness of 1.5 mm). After heating the molded body to an appropriate temperature to remove the solvent, use a compression molding machine without a magnetic field for 8 tons.
Coining was performed at a pressure of / cm ² , followed by heat curing to obtain a radially anisotropic bonded magnet according to the present invention. The porosity of this bonded magnet was in the range of 5 to 22%. Next, symmetrical 8-pole polar anisotropic magnetization (magnetization magnetic field of about 5 kO
After performing e), the surface magnetic flux density was measured. As a result, good results substantially equivalent to those in FIG. 2 were obtained. (Comparative Example 10) The compound of Comparative Example 4 was used and the molding machine of Example 4 was used without a magnetic field and 8 ton / cm ^2.
Dry compression molding at a molding pressure of 25 mm in outer diameter and 22 mm in inner diameter
Thus, a bonded magnet molded body having a thickness of 1.5 mm and a thickness of 1.5 mm was obtained. Next, after performing a heat curing treatment, symmetric 8-pole anisotropic magnetization was performed under the same conditions as in Example 4, and the results of measuring the surface magnetic flux density are shown in FIG. 2, the surface magnetic flux density of the polar anisotropic bonded magnet of this comparative example was a low value of about 1700 G.

According to the studies related to Examples 4 and 5, according to the present invention, the orientation magnetic field strength of 3 to 50 mm in inner diameter is about 3 mm.
Rare earths produced under conditions limited to 10 kOe
An iron / nitrogen-based bonded magnet having a corresponding outer diameter of 4 to 51
mm, a radially anisotropic ring shape having a dimension of 50 mm or less in thickness, or a symmetric or asymmetric polar anisotropic ring shape of 4 to 16 poles, or a radially anisotropic arc segment shape corresponding to the dimensions, or The surface magnetic flux density of a polar anisotropic arc segment having a size corresponding to the dimension may be preferably 2300 G or more, more preferably 2600 G or more, and particularly preferably 3000 G or more.

The ratio of the thermosetting resin in the bonded magnet of the present invention is not particularly limited. For example, the ratio of the liquid thermosetting resin in the molding compound is 0.5 to 20 watts.
It is good to be t%. If it exceeds 20 wt%, the superiority of high Br and high (BH) max over conventional injection molded products is lost. If it is less than 0.5% by weight, the binding strength is greatly reduced.

In the above, the examples of the application for compression molding have been described. However, it is expected that the superiority of the present invention can be realized even for the application for injection molding having a relatively low mixing ratio of magnet powder.

According to the present invention, the crystal structure phase of ThMn ₁₂ type is used as the main phase of the magnet, and Nd _{5 to 10} T in atomic%.
_bal N ₃ to 13 and a magnetic alloy powder having a powder particle size distribution of 0.5 to 30 μm (T is F
e or Fe and Co) to obtain a higher B
r, it is also possible to realize a magnetic anisotropic bonded magnet by a compression molding method in a wet magnetic field having a high (BH) max. When Nd deviates from 5 to 10 atomic% and N deviates from 3 to 13 atomic%, a higher Br and a higher (BH) than the conventional injection molded product are obtained.
It is difficult to secure the superiority of max.

[0026]

As described above, according to the present invention, it is possible to provide a rare earth / iron / nitrogen based magnetically anisotropic bonded magnet exhibiting good orientation even at a low orientation field strength and a method for producing the same. .

[Brief description of the drawings]

FIG. 1 Pressure and porosity during coining, (BH) max
FIG. 4 is a diagram showing an example of the correlation of FIG.

FIG. 2 is a diagram showing an example of a surface magnetic flux density waveform of the magnetic anisotropic bonded magnet of the present invention.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01F 1/053 B22F 3/02 R 7/02 3/10 B 41/02 H01F 1/04 A (72) Inventor Okajima Hiroshi 5200 Sankajiri, Kumagaya-shi, Saitama F-term in the Magnetic Materials Research Laboratories, Hitachi Metals, Ltd. 4K018 BB04 CA04 CA07 CA33 DA03 DA11 FA02 KA46 5E040 AA03 AA19 BB05 CA01 HB05 HB06 NN01 NN06 NN14 NN17 NN18 5E062 CD04 CE04CG01

Claims (6)

[Claims] 1. A liquid mixture of a rare-earth / iron / nitrogen-based magnetic material powder exhibiting magnetic anisotropy and a liquid thermosetting resin and an organic solvent having a boiling point lower than the curing start temperature of the liquid thermosetting resin. Into a slurry, and the slurry is subjected to wet molding by a compression molding method in a wet magnetic field, and the obtained molded body is at a temperature equal to or higher than the boiling point of the organic solvent and lower than the curing start temperature of the liquid thermosetting resin. A method for producing a magnetically anisotropic bonded magnet, characterized by increasing the density of a compact by carrying out coining or sizing as necessary, after removing the solvent while maintaining the temperature of the solvent. 2. The method for producing a magnetically anisotropic bonded magnet according to claim 1, wherein the magnet is molded in a wet magnetic field at room temperature. 3. The composition of a rare earth / iron / nitrogen based magnetic material powder exhibiting magnetic anisotropy is R _α T _{100−α−β} N _β , (R
Is one or more of the rare earth elements containing Y, and Sm
Wherein T is Fe or Fe and Co), and α and β are each in atomic percentage and 5 ≦ α ≦ 20 and 5 ≦ β ≦ 30. The magnetic anisotropic bonded magnet according to claim 1 or 2, wherein Production method. 4. The magnetic anisotropic bonded magnet according to claim 1, wherein the rare earth / iron / nitrogen based magnetic material powder exhibiting magnetic anisotropy has a particle size distribution of 0.5 to 30 μm. Production method. 5. The method for producing a magnetically anisotropic bonded magnet according to claim 1, wherein the liquid thermosetting resin is an epoxy resin, and the organic solvent is a ketone having a boiling point of less than 130 ° C. 6. The particle size distribution is 0.5 to 30 μm, and R _α T _{100-α -β} N _β , wherein R is at least one kind of rare earth element including Y and always contains Sm , T is F
e or Fe and Co), α and β are each an atomic percentage and a magnetically anisotropic rare-earth / iron / nitrogen-based magnet material powder having a composition represented by 5 ≦ α ≦ 20 and 5 ≦ β ≦ 30, and thermosetting. A magnetic anisotropic bonded magnet consisting essentially of a conductive resin, having a porosity of 5 to 22%, and having a maximum energy product ((BH) max) of 10 MGOe or more at 20 ° C. Magnetic anisotropic bonded magnet.