JPH09180919A - Rare-earth bonded magnet, its composition and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare-earth bonded magnet having excellent moldability, magnetic characteristics and high mechanical strength making the best use of the advantages of extrusion molding. SOLUTION: The rare-earth bonded magnet is a magnet which is extrusion molded, and it contains rare-earth magnet powder and thermoplastic resin. The content of the rare-earth magnet powder is 78.1 to 83mol%. For example, an Sm-Co alloy, an R-Fe-B alloy (R indicates at least a kind selected from Y-containing rare-earth elements) and Sm-Fe-N alloy or the material properly mixed them are used as the rare-earth magnet powder. For example, liquid crystal polymer and PPS are used as the thermoplastic resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rare earth bonded magnet, a composition for a rare earth bonded magnet, and a method for producing a rare earth bonded magnet.

[0002]

2. Description of the Related Art A rare earth bonded magnet is manufactured by press-molding a mixture (compound) of rare earth magnet powder and a binder resin (organic binder) into a desired magnet shape. , Compression molding method, injection molding method and extrusion molding method are used.

In the compression molding method, the compound is filled in a press mold, and the molded product is compression-molded to obtain a molded body, which is then heated to cure a thermosetting resin which is a binding resin to produce a magnet. Is the way to do it. Compared to other methods, this method allows molding even with a small amount of binding resin,
The amount of resin in the obtained magnet is small, which is advantageous for improving the magnetic characteristics, but the degree of freedom in the shape of the magnet is small.

The extrusion molding method is a method of extruding a heated and melted compound from a mold of an extrusion molding machine, solidifying it by cooling, cutting it into a desired length, and forming a magnet.
In this method, there is a large degree of freedom with respect to the shape of the magnet, and there is an advantage that thin and long magnets can be easily manufactured, but in order to secure the fluidity of the melt during molding,
It is necessary to increase the addition amount of the binder resin compared to that of the compression molding method, and therefore, the resin amount in the obtained magnet is large,
There is a drawback that the magnetic properties are degraded.

The injection molding method is a method in which the compound is heated and melted, and the melt is injected into a mold in a state of having sufficient fluidity to mold it into a predetermined magnet shape. With this method, the degree of freedom with respect to the shape of the magnet is greater than that of the extrusion molding method, and in particular, there is an advantage that a magnet with a different shape can be easily manufactured. However, since the flowability of the melt at the time of molding is required to be higher than that of the extrusion molding method, the addition amount of the binder resin needs to be increased more than that of the extrusion molding method, and therefore, In addition, there is a drawback that the amount of resin in the magnet is large and the magnetic properties are further deteriorated.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to obtain the moldability of a small amount of binder resin while taking advantage of the advantages of extrusion molding.
It is an object of the present invention to provide a rare earth bonded magnet having excellent magnetic properties, a composition for a rare earth bonded magnet capable of obtaining such a magnet, and a method for producing the rare earth bonded magnet.

[0007]

This and other objects are achieved by the present invention which is defined below as (1) to (14).

(1) A rare earth bonded magnet produced by extrusion molding using a composition for a rare earth bonded magnet containing the rare earth magnet powder and a thermoplastic resin, the content of the rare earth magnet powder in the rare earth bonded magnet. But 78.1-8
A rare earth bonded magnet characterized by being 3 vol%.

(2) The rare earth bonded magnet according to the above (1), which has a porosity of 2 vol% or less.

(3) The thermoplastic resin has a melting point of 40.
The rare earth bonded magnet according to the above (1) or (2), which has a temperature of 0 ° C. or less.

(4) The rare earth bonded magnet according to any one of (1) to (3), wherein the thermoplastic resin is polyamide, liquid crystal polymer or polyphenylene sulfide.

(5) The rare earth magnet powder contains a rare earth element mainly containing Sm and a transition metal mainly containing Co as basic components. Rare earth bonded magnet.

(6) The rare earth magnet powder is R (where R is at least one of rare earth elements containing Y).
The rare earth bonded magnet according to any one of the above (1) to (4), which has a transition metal mainly composed of Fe, and B as basic components.

(7) The rare earth magnet powder contains a rare earth element containing Sm as a main component, a transition metal containing Fe as a main component, and an interstitial element containing N as a main component. ) To (4) The rare earth bonded magnet according to any one of (4) to (4).

(8) The rare earth magnet powder is a mixture of at least two of the rare earth magnet powders described in (5), (6) and (7) above.
The rare earth bonded magnet according to any one of (4) to (4).

(9) The rare earth bonded magnet according to any one of the above (1) to (8), which has a magnetic energy product (BH) max of 8 MGOe or more when molded in a non-magnetic field.

(10) The rare earth bonded magnet according to any one of (1) to (8) above, which has a magnetic energy product (BH) max of 12 MGOe or more when molded in a magnetic field.

(11) A composition for a rare earth bond magnet, which comprises rare earth magnet powder, a thermoplastic resin, and an antioxidant and is used for extrusion molding, wherein the rare earth magnet powder in the composition for the rare earth bond magnet is Content of 77.6-82.
A composition for a rare earth bonded magnet, which is 5 vol%.

(12) A composition for a rare earth bond magnet, which comprises rare earth magnet powder, a thermoplastic resin, and an antioxidant and is used for extrusion molding, wherein the thermoplastic resin in the composition for the rare earth bond magnet is used. The total content of the antioxidant and the antioxidant is 15.0 to 22.4 vol%, a rare earth bonded magnet composition.

(13) The content of the antioxidant in the rare earth bonded magnet composition is 2.0 to 12.0 vol%.
The composition for a rare earth bonded magnet according to the above (11) or (12), which is

(14) The composition for rare earth bonded magnet according to any one of the above (11) to (13) is kneaded, and the kneaded product is molded into a magnet shape by an extrusion molding method. Manufacturing method of rare earth bonded magnet.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The rare earth bonded magnet, the composition for rare earth bonded magnet, and the method for producing the rare earth bonded magnet of the present invention will be described in detail below.

First, the rare earth bonded magnet of the present invention will be described. The rare earth bonded magnet of the present invention is manufactured by extrusion molding and contains the following rare earth magnet powder and a binder resin made of a thermoplastic resin. Furthermore, it is preferable to contain the following antioxidants.

1. Rare earth magnet powder The rare earth magnet powder is preferably made of an alloy containing a rare earth element and a transition metal. In particular, the following [1]-
[4] is preferred.

[1] A rare earth element mainly containing Sm and C
Those containing a transition metal mainly containing o as a basic component (hereinafter,
Sm-Co based alloy).

[2] R (where R is at least one of rare earth elements including Y), a transition metal mainly containing Fe, and B as basic components (hereinafter, R-Fe-B)
System alloy).

[3] A rare earth element mainly composed of Sm and F
A transition metal mainly composed of e and an interstitial element mainly composed of N (hereinafter, referred to as Sm-Fe-N-based alloy).

[4] A mixture of at least two of the compositions [1] to [3]. In this case, it is possible to have the advantages of each magnet powder to be mixed, and it is possible to easily obtain more excellent magnetic characteristics.

Typical examples of Sm-Co alloys include SmCo ₅ and Sm ₂ TM ₁₇ (where TM is a transition metal).

Typical R-Fe-B alloys are Nd-Fe-B alloys, Pr-Fe-B alloys, and N-Fe-B alloys.
Substitution of d-Pr-Fe-B based alloy, Ce-Nd-Fe-B based alloy, Ce-Pr-Nd-Fe-B based alloy, and some of Fe in these with other transition metals such as Co and Ni The ones that have been made are listed.

[0031] Typical examples of the Sm-Fe-N based alloy was prepared by nitriding the Sm ₂ Fe ₁₇ alloy Sm ₂ Fe
₁₇ N ₃ .

The rare earth elements in the magnet powder include Y, La, Ce, Pr, Nd, Pm, Sm, Eu,
Examples thereof include Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and misch metal, and one or more of these may be included. The transition metal may be F
e, Co, Ni, etc. are mentioned, and these can be contained 1 type or 2 types or more. Further, in order to improve magnetic properties, B, Al, Mo,
Cu, Ga, Si, Ti, Ta, Zr, Hf, Ag, Z
It may also contain n and the like.

The average particle size of the magnet powder is not particularly limited, but is preferably about 0.5 to 50 μm, and 1 to 30.
It is more preferably about μm. Further, in order to obtain a good moldability at the time of extrusion molding with a small amount of a binder resin as described later, it is preferable that the particle size distribution of the magnet powder is dispersed to some extent (varies). Thereby, the porosity of the obtained bonded magnet can also be reduced. In the case of the above [4], the average particle size may differ depending on the composition of the magnet powder to be mixed.

The method for producing the magnet powder is not particularly limited,
For example, an alloy ingot is produced by melting and casting, and the alloy ingot is crushed to an appropriate particle size (classified), and a quenched ribbon manufacturing apparatus used to manufacture an amorphous alloy is used to form a ribbon. Quenched flakes (a collection of fine polycrystals) may be produced, and the flakes (ribbons) may be pulverized to an appropriate particle size (further classified), or any other material obtained.

The content of such rare earth magnet powder is 7
It is about 8.1 to 83 vol%, especially 79.5 to 83
It is preferably about vol%, and more preferably about 81 to 83 vol%. If the content of the magnet powder is too small, the magnetic properties (especially the magnetic energy product) cannot be improved, and if the content of the magnet powder is too large, the content of the binding resin becomes relatively small, so the extrusion The fluidity at the time of molding decreases, making molding difficult or impossible.

2. Binding resin (binder) As the binding resin (binder), a thermoplastic resin is used. When a thermosetting resin such as an epoxy resin which has been conventionally used as a binding resin is used,
Since the fluidity during molding is poor, the moldability is poor, the porosity of the magnet is increased, and the mechanical strength and corrosion resistance are low,
When a thermoplastic resin is used, such a problem is solved. Further, the thermoplastic resin can be selected in a wide range depending on its type, copolymerization and the like, for example, one in which moldability is emphasized, one in which heat resistance and mechanical strength are emphasized.

As the thermoplastic resin which can be used, for example, polyamide (eg nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), thermoplastic polyimide , Liquid crystal polymers, polyphenylene oxide, polyphenylene sulfide, polyolefins such as polyethylene and polypropylene, modified polyolefins,
Examples thereof include polyethers, polyacetals, and the like, and copolymers, blends, and polymer alloys containing these as the main components, and one or more of these can be used as a mixture.

Among them, those mainly composed of a liquid crystal polymer and polyphenylene sulfide are preferred from the viewpoint of polyamide and heat resistance improvement because the moldability in extrusion molding is more remarkable and the mechanical strength is strong. Of these, those mainly containing polyamide or polyphenylene sulfide are particularly preferable. Further, these thermoplastic resins are also excellent in kneading property with magnet powder and uniformity of kneading.

The thermoplastic resin used has a melting point of 400.
It is preferably not higher than 300C, more preferably not higher than 300C. If the melting point exceeds 400 ° C,
The temperature at the time of molding rises, and the magnet powder or the like is easily oxidized.

The average molecular weight (degree of polymerization) of the thermoplastic resin used to further improve the fluidity and moldability
Is preferably about 10,000 to 60,000,
It is more preferably about 12,000 to 30,000.

3. Antioxidant The antioxidant is an oxide (deterioration, deterioration) of the rare earth magnet powder or an oxidation of the binding resin (the metal component of the rare earth magnet powder acts as a catalyst when mixing the composition for the rare earth bonded magnet described later). Caused by) are added in the composition to prevent the above. The addition of this antioxidant is
It contributes to prevent the oxidation of rare earth magnet powder and to improve the magnetic properties of the magnet, and also contributes to the improvement of thermal stability at the time of kneading and molding of the composition for rare earth bonded magnet, thus reducing the amount of binder resin. And plays an important role in ensuring good moldability.

This antioxidant volatilizes or deteriorates in an intermediate step such as kneading or molding of the composition for a rare earth bonded magnet, so that a part thereof is produced in the manufactured rare earth bonded magnet. It exists in a residual state. Therefore, the content of the antioxidant in the rare earth bonded magnet is relative to the amount of the antioxidant added in the composition for the rare earth bonded magnet,
For example, it is about 10 to 90%, particularly about 20 to 80%.

The antioxidant may be any one as long as it can prevent or suppress the oxidation of the rare earth magnet powder and the like, and examples thereof include amine compounds, amino acid compounds, nitrocarboxylic acids, hydrazine compounds and cyan compounds. A chelating agent that forms a chelate compound with respect to metal ions, particularly Fe component, such as sulfide, is preferably used. It goes without saying that the type, composition and the like of the antioxidant are not limited to these.

In such a rare earth bonded magnet of the present invention, the porosity is preferably 2 vol% or less,
It is more preferably 1.5 vol% or less. Porosity is 2
If it exceeds vol%, the mechanical strength and corrosion resistance of the magnet may decrease depending on other conditions such as the composition and content of the magnet powder and the composition of the thermoplastic resin.

In the rare earth bonded magnet of the present invention as described above, the composition of the magnet powder, the large content of the magnet powder, etc.
Even an isotropic magnet has excellent magnetic properties.

That is, the rare earth bonded magnet of the present invention is
In the case of those molded in a non-magnetic field, the magnetic energy product (B
H) max is preferably 8 MGOe or more, more preferably 10 MGOe or more. Further, in the case of molding in a magnetic field, the magnetic energy product (BH) max is preferably 12 MGOe or more, more preferably 14 MGOe or more.

The shape of the rare earth bonded magnet of the present invention,
The size and the like are not particularly limited, and for example, regarding the shape, any shape such as a columnar shape, a prismatic shape, a cylindrical shape, an arc shape, a flat plate shape, and a curved plate shape can be used, and the size thereof is large. It can be of any size, from small to very small.

Next, the composition for rare earth bonded magnet of the present invention will be explained.

The rare earth bonded magnet composition of the present invention is mainly composed of the above-mentioned rare earth magnet powder, the above-mentioned thermoplastic resin, and the above-mentioned antioxidant.

In this case, the content (addition amount) of the rare earth magnet powder in the composition for rare earth bonded magnets is 77.6-8.
It is preferably about 2.5 vol%, 79 to 82.5
It is more preferable to set it to about vol%, and 80.5 to 82.
It is more preferable to set the content to about 5 vol%. If the content of the magnet powder is too small, the magnetic properties (especially the magnetic energy product) cannot be improved, and if the content of the magnet powder is too large, the content of the binding resin becomes relatively small, so the extrusion The fluidity at the time of molding decreases, making molding difficult or impossible.

The content (addition amount) of each of the thermoplastic resin and the antioxidant in the composition for a rare earth bonded magnet is such that the type, composition, molding temperature, pressure, etc. of the thermoplastic resin and the antioxidant are molded. It varies depending on various conditions such as conditions, shape and size of the molded product. In order to improve the magnetic properties of the obtained rare earth bonded magnet, the amount of the thermoplastic resin added to the composition for a rare earth bonded magnet is preferably as small as possible within the range where kneading and molding are possible.

The amount of the antioxidant added to the rare earth bonded magnet composition is preferably about 2.0 to 12.0 vol%, and about 3.0 to 10.0 vol%. Is more preferable. In this case, the addition amount of the antioxidant is preferably about 10 to 150%, more preferably about 25 to 90% with respect to the addition amount of the binder resin.

In the present invention, it goes without saying that the amount of the antioxidant added may be not more than the lower limit value of the above range, or may be no addition.

If the amount of the thermoplastic resin added to the composition for rare-earth bonded magnets is too small, the viscosity of the kneaded material when kneading the composition for rare-earth bonded magnets will increase and the kneading torque will increase, resulting in heat generation of the magnet powder. If the amount of antioxidants added is small, the oxidation of magnet powder cannot be sufficiently suppressed and the viscosity of the kneaded product (resin melt) increases. As a result, the moldability is poor, and a magnet with low porosity and high mechanical strength cannot be obtained.
Further, if the amount of the thermoplastic resin added is too large, the moldability is good, but the content of the binder resin in the obtained magnet is large and the magnetic properties are deteriorated.

On the other hand, when the amount of the antioxidant added to the composition for rare earth bonded magnet is too small, the antioxidant effect is small, and when the content of the magnet powder is large, the oxidation of the magnet powder or the like is sufficiently suppressed. Can't do it. Further, when the amount of the antioxidant added is too large, the amount of resin is relatively decreased, and the mechanical strength of the molded product tends to be lowered.

As described above, if the amount of the thermoplastic resin added is relatively large, the amount of the antioxidant added can be reduced. Conversely, if the amount of the thermoplastic resin added is small, the amount of the antioxidant added is small. It is necessary to increase the amount.

Therefore, the total amount of the thermoplastic resin and the antioxidant added in the rare earth bonded magnet composition is 15.0 to.
It is preferably 22.4 vol%, and 15.0 to 20.
5 vol% is more preferable, and 15.0 to 18.5
More preferably, it is vol%. When the content is in such a range, it contributes to improvement of fluidity and moldability during extrusion molding, and prevention of oxidation of magnet powder and the like, and a magnet having low porosity, high mechanical strength and high magnetic properties can be obtained.

In addition, the rare earth bonded magnet composition may include, for example, a plasticizer (eg, stearate, fatty acid) that plasticizes the binding resin, a lubricant (eg, silicone oil, various waxes, fatty acids), if necessary. , Various inorganic lubricants such as alumina, silica, and titania), and various additives such as molding aids can also be added.

Since the addition of the plasticizer improves the fluidity at the time of molding, the same characteristics can be obtained with a smaller amount of the binder resin added, which is preferable. The same applies to the addition of a lubricant. The addition amount of the plasticizer is preferably about 0.1 to 2.0 vol%, and the addition amount of the lubricant is 0.2 to 2.
It is preferably about 5 vol%.

Next, a method of manufacturing the rare earth bonded magnet of the present invention will be described. The method for producing a rare earth bonded magnet of the present invention is performed as follows using the composition for a rare earth bonded magnet described above.

A rare earth bonded magnet composition (mixture) containing rare earth magnet powder, a thermoplastic resin, and an antioxidant is sufficiently kneaded alone or by using a kneader attached to an extruder. At this time, the kneading temperature is preferably about 150 to 350 ° C.

The obtained kneaded product (compound) is heated in a cylinder of an extrusion molding machine to a temperature equal to or higher than the melting temperature of the thermoplastic resin and melted. Is, for example, 10 to 20 kOe) and is extruded from the die of the extruder. At this time, the material temperature in the cylinder is preferably about 20 to 330 ° C., and the extrusion speed is
0.1 to 10 mm / sec is preferable, and the mold temperature is 20
About 0 to 350 ° C. is preferable.

The molded body is cooled and solidified when it is extruded from a die, for example. The extruded long molded body is appropriately cut to obtain a rare earth bonded magnet having a desired shape and size.

The cross-sectional shape of the rare earth bonded magnet is determined by selecting the shape of the die (inner die and outer die),
It can be easily manufactured even if it is thin or has an irregular cross section. Also, a long magnet can be manufactured by adjusting the cutting length of the molded body.

By the method as described above, the flexibility of the magnet shape is wide, the flowability and the moldability are excellent even with a small amount of resin, the dimensional accuracy is high, and the continuous production is possible.
A rare earth bonded magnet suitable for mass production can be manufactured.

Needless to say, the kneading conditions and molding conditions are not limited to those in the above range.

[0067]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described.

(Examples 1 to 12, Comparative Examples 1 and 2) Six kinds of rare earth magnet powders having the following compositions:
The following three types of thermoplastic resins (bonding resins) A, B and C,
Prepare N, N-diphenyloxamide (chelating agent) as an antioxidant, fatty acid as a lubricant, and metallic soap as a plasticizer, and mix them in a predetermined combination and amount shown in Table 1 below. A composition for a rare earth bonded magnet was obtained.

Quenched Nd ₁₂ Fe ₈₂ B ₆ powder (average particle size =
18 μm) Quenched Nd ₈ Pr ₄ Fe ₈₂ B ₆ powder (average particle size = 17 μm
m) Quenched Nd ₁₂ Fe ₇₈ Co ₄ B ₆ powder (average particle size = 19μ
m) Sm (Co _0.604 Cu _0.06 Fe _0.32 Zr _0.016 ) _8.3 powder (average particle size = 21 μm) Sm ₂ Fe ₁₇ N ₃ powder (average particle size = 2 μm) Anisotropy according to HDDR method Nd ₁₃ Fe ₆₉ Co ₁₁ B ₆ Ga
₁ powder (average particle size = 28 μm) A. Polyamide (nylon 12), melting point: 175 ° C. B.I. Liquid crystal polymer, melting point: 180 ° C. Polyphenylene sulfide (PPS), melting point: 2
80 ° C. Next, each composition for rare earth bonded magnets shown in Table 1 was sufficiently kneaded by using a screw-type kneader to produce a compound, and then extruded by an extruder using the compound, A rare earth bonded magnet was manufactured.

The kneading conditions and molding conditions at this time are shown in Tables 2 and 3 below. Also, the shape, dimensions, and
The composition, appearance (visual observation), and various properties are shown in Tables 4, 5, and 6 below.

The mechanical strengths shown in Tables 4 to 6 are obtained by separately extruding a test piece having an outer diameter of 15 mm and a height of 3 mm in the absence of a magnetic field under the conditions shown in Tables 2 and 3. Was evaluated by the shear punching method.

The corrosion resistances shown in Tables 4 to 6 are 80 ° C. and 9 ° C. in a constant temperature and humidity chamber for the obtained rare earth bonded magnets.
An accelerated test was performed under the condition of 0% RH, and the time until rust was generated was evaluated in four grades of ⊚, ○, Δ and ×.

(Comparative Example 3) The compositions for rare earth bonded magnets shown in Table 1 were sufficiently kneaded using a screw type kneader to produce a compound, which was then injection molded using an injection molding machine. Then, a rare earth bonded magnet was manufactured.

The kneading conditions and molding conditions at this time are shown in Table 3 below. Also, the shape, size, composition of the obtained magnet,
The appearance (visual observation) and various properties are shown in Table 6 below.

(Comparative Example 4) Magnet powder and epoxy resin (thermosetting resin) were mixed in the ratio shown in Table 1 below, and this mixture was kneaded at room temperature. The compound obtained was shown in Table 3 below. Compression molding (press molding) was performed under the conditions, and the molded body was heat-treated at 150 ° C. for 1 hour to cure the resin to obtain a rare earth bonded magnet.

The shape, dimensions, composition, appearance (visual observation) and various properties of the obtained magnet are shown in Table 6 below.

The mechanical strength shown in Table 6 was obtained by separately subjecting a test piece having an outer diameter of 15 mm and a height of 3 mm to compression molding under the conditions shown in Table 3 in the absence of a magnetic field, and using the test piece to perform a shear punching method. evaluated. The corrosion resistance was evaluated in the same manner as above.

[0078]

[Table 1]

[0079]

[Table 2]

[0080]

[Table 3]

[0081]

[Table 4]

[0082]

[Table 5]

[0083]

[Table 6]

As shown in each table, the rare earth bonded magnets of Examples 1 to 12 all have low porosity, excellent formability, magnetic characteristics (magnetic energy product), corrosion resistance, and high mechanical strength. It was confirmed to be a thing.

On the other hand, in the rare earth bonded magnet of Comparative Example 1, the content of the rare earth magnet powder was too large, so that the composition for the rare earth bonded magnet could not be kneaded.

Further, in Comparative Example 2, since the antioxidant and the lubricant were added, it was possible to knead the composition for a rare earth bonded magnet, but since the content of the rare earth magnet powder was too large, the extrusion molding was performed. Moldability was poor.

In Comparative Example 3, injection molding was impossible because the fluidity required for injection molding could not be ensured.

In Comparative Example 4, the resin exudes on the outer surface of the magnet, which is abnormal.

[0089]

As described above, according to the present invention, while the advantages of extrusion molding that the magnet has a large degree of freedom in shape and size, high dimensional accuracy, and suitable for mass production,
It is possible to provide a rare earth bonded magnet having a small amount of binding resin, excellent moldability and corrosion resistance, high mechanical strength, and excellent magnetic properties.

In particular, these characteristics are superior to the rare earth bonded magnet manufactured by injection molding.

Claims (14)

[Claims] 1. A rare earth bonded magnet produced by extrusion molding using a composition for a rare earth bonded magnet containing rare earth magnet powder and a thermoplastic resin, wherein the content of the rare earth magnet powder in the rare earth bonded magnet is ,
A rare earth bonded magnet characterized in that it is 78.1 to 83 vol%. 2. The rare earth bonded magnet according to claim 1, which has a porosity of 2 vol% or less. 3. The rare earth bonded magnet according to claim 1, wherein the thermoplastic resin has a melting point of 400 ° C. or lower. 4. The rare earth bonded magnet according to claim 1, wherein the thermoplastic resin is polyamide, liquid crystal polymer or polyphenylene sulfide. 5. The rare earth bonded magnet according to claim 1, wherein the rare earth magnet powder contains a rare earth element mainly containing Sm and a transition metal mainly containing Co as basic components. . 6. The rare earth magnet powder is R (provided that R
Is at least one of rare earth elements including Y), and Fe
The rare earth bonded magnet according to any one of claims 1 to 4, which comprises a transition metal mainly containing B and B as a basic component. 7. The rare earth magnet powder contains a rare earth element mainly containing Sm, a transition metal mainly containing Fe, and an interstitial element mainly containing N as a basic component. 4. The rare earth bonded magnet according to any one of 4 above. 8. The rare earth bonded magnet according to claim 1, wherein the rare earth magnet powder is a mixture of at least two of the rare earth magnet powders according to claims 5, 6 and 7. . 9. The rare earth bonded magnet according to claim 1, which has a magnetic energy product (BH) max of 8 MGOe or more when molded in a non-magnetic field. 10. The magnetic energy product (BH) max when molded in a magnetic field is at least 12 MGOe.
The rare earth bonded magnet according to any one of 1. 11. A composition for a rare earth bond magnet, which comprises rare earth magnet powder, a thermoplastic resin, and an antioxidant and is subjected to extrusion molding, wherein the rare earth magnet powder in the composition for the rare earth bond magnet is Content is 77.6-82.5 vol%, The composition for rare earth bonded magnets characterized by the above-mentioned. 12. A composition for a rare earth bond magnet, which comprises rare earth magnet powder, a thermoplastic resin, and an antioxidant and is subjected to extrusion molding, wherein the thermoplastic resin in the composition for the rare earth bond magnet is The total content with the antioxidant is 15.0 to 22.4.
A composition for a rare earth bonded magnet, characterized in that it is vol%. 13. The composition for a rare earth bonded magnet according to claim 11, wherein the content of the antioxidant in the composition for a rare earth bonded magnet is 2.0 to 12.0 vol%. 14. A rare earth bonded magnet, characterized by kneading the composition for a rare earth bonded magnet according to claim 11 and molding the kneaded material into a magnet shape by an extrusion molding method. Production method.