JP2002151314A - Method of manufacturing bonded magnet and the bonded magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing bonded magnet with which a bonded magnet having superior magnetic characteristics can be manufactured, and to provide the bonded magnet. SOLUTION: The bonded magnet is manufactured, by kneading magnet powder with a material containing a binder and molding the kneaded product. The kneading is performed, while the magnet powder is pulverized, so that the mean particle diameter of the powder after kneading becomes smaller than that of the powder before kneading. It is preferable that the magnet powder be pulverized to satisfy the relation 0.1<=D1/D0<=0.9 (where D0 (μm) and D1 (μm) respectively denotes the mean particle diameters of the powder before and after kneading). It is also preferable that the mean particle diameter D0 be adjust before kneading to 10-1,200 μm and the mean particle diameter D1 after kneading to 1-500 μm. In addition, it is also preferable that the kneading be conducted in an inert gas atmosphere and that an antioxidant be mixed in the material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a bonded magnet and a bonded magnet.

[0002]

2. Description of the Related Art In order to reduce the size of a motor or the like, it is desired that the magnetic flux density (in substantial permeance) of a magnet used in the motor be high. Factors that determine the magnetic flux density of the bonded magnet include the magnetization value of the magnet powder and the content (content) of the magnet powder in the bonded magnet. Therefore, when the magnetization of the magnet powder itself is not so high, a sufficient magnetic flux density cannot be obtained unless the content of the magnet powder in the bonded magnet is increased.

[0003] When the particle size of the magnet powder in the bonded magnet is large, it is difficult to increase the content of the magnet powder, and the formability of the bonded magnet is reduced. For this reason, conventionally, finely pulverized magnet powder has been used in the production of bonded magnets. However, when the magnet powder thus finely pulverized is used for manufacturing a bonded magnet, the magnet powder is easily oxidized and deteriorated in the pulverizing step, the manufacturing step of the bonded magnet, and the like. For this reason, satisfactory magnetic characteristics may not be obtained in spite of the high content of the magnet powder in the obtained bonded magnet.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a bonded magnet and a bonded magnet capable of providing a magnet having excellent magnetic properties.

[0005]

This and other objects are achieved by the present invention which is defined below as (1) to (22).

(1) A method for producing a bonded magnet, comprising: a step of kneading a material containing magnet powder and a binder to obtain a kneaded material; and a step of molding the kneaded material to obtain a molded body. The kneading is performed while pulverizing the magnet powder so that the average particle diameter of the magnet powder after the kneading is smaller than the average particle diameter of the magnet powder before the kneading. Manufacturing method of bonded magnet.

(2) a step of producing a magnet powder, a step of kneading a material containing the magnet powder and a binder to obtain a kneaded material, and a step of molding the kneaded material to obtain a molded body. A method for manufacturing a bonded magnet, wherein the magnet powder is manufactured such that the average particle size is larger than the final average particle size, and the final average particle size is obtained by the kneading. A method for producing a bonded magnet.

(3) When the average particle size of the magnet powder before kneading is D ₀ [μm] and the average particle size of the magnet powder after kneading is D ₁ [μm], the following formula (I) The method for producing a bonded magnet according to the above (1) or (2), which satisfies the condition (1).

0.1 ≦ D ₁ / D ₀ ≦ 0.9 (I) (4) Any one of the above (1) to (3), wherein the material contains an antioxidant. Of manufacturing bonded magnets.

(5) The method for producing a bonded magnet according to any one of the above (1) to (4), wherein the average particle diameter of the magnet powder before the kneading is 10 to 1200 μm.

(6) The method for producing a bonded magnet according to any one of the above (1) to (5), wherein the average particle size of the magnet powder after completion of the kneading is 1 to 500 μm.

(7) The bond magnet according to any one of (1) to (6), wherein the kneading is performed by applying a kneading energy of 0.07 to 3.5 kWh per liter of the material. Production method.

(8) The method for producing a bonded magnet according to any one of the above (1) to (7), wherein the content of the magnet powder in the material is 50 to 95 vol%.

(9) The method for manufacturing a bonded magnet according to any one of the above (1) to (8), wherein the kneading is performed in an inert gas atmosphere.

(10) The method for producing a bonded magnet according to any one of the above (1) to (9), wherein the kneading is performed using a continuous twin-screw extruder or a continuous twin-screw roll.

(11) The method for producing a bonded magnet according to any one of the above (1) to (10), wherein the molding is performed by any one of compression molding, extrusion molding, and injection molding.

(12) The method for producing a bonded magnet according to any one of the above (1) to (11), wherein the magnet powder contains a rare earth element.

(13) The magnet powder is R-TM-B
Alloys (where R is at least one rare earth element, T
The method for producing a bonded magnet according to any one of the above (1) to (12), wherein M is a transition metal mainly composed of Fe).

(14) The method for producing a bonded magnet according to any one of the above (1) to (13), wherein the magnet powder has a composite structure having a hard magnetic phase and a soft magnetic phase.

(15) Each of the hard magnetic phase and the soft magnetic phase has an average crystal grain size of 1 to 100 nm.
The method for producing a bonded magnet according to the above (14), wherein

(16) The method according to any one of the above (1) to (15), wherein the binder contains a thermoplastic resin or a thermosetting resin.

(17) The method for producing a bonded magnet according to any one of the above (1) to (16), wherein the kneading is performed at a temperature equal to or higher than the softening point of the binder.

(18) A bonded magnet manufactured by the manufacturing method according to any one of (1) to (17).

(19) Density of 4.0 to 8.0 Mg / m
^3. The bonded magnet according to the above (18), which is ³ .

(20) The intrinsic coercive force H _cJ at room temperature is 40
(18) or (1), which is 0 to 1500 kA / m.
The bonded magnet according to 9).

(21) Maximum magnetic energy product (BH)
(18) to (2) wherein _max is 50 kJ / m ³ or more.
0) The bonded magnet according to any one of the above.

(22) The bonded magnet according to any one of (18) to (21), wherein the absolute value of the irreversible demagnetization rate (initial demagnetization rate) is 8% or less.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a bonded magnet and an embodiment of a bonded magnet according to the present invention will be described in detail.

[Alloy composition of magnet powder] First, the alloy composition of the magnet powder in the present invention will be described.

The alloy composition may be any, but preferably contains a rare earth element. Examples of such a magnet powder include the following [1]-
And the like having the composition of [3].

[1] A rare earth element mainly composed of Sm and C
a transition metal mainly composed of o (hereinafter, referred to as a basic component)
Sm-Co alloy).

[2] R (where R is at least 1
Rare earth elements) and transition metals (TM) mainly composed of Fe
And B as basic components (hereinafter referred to as an R-TM-B alloy).

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

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

Representative R-TM-B alloys include Nd-Fe-B alloys, Pr-Fe-B alloys, and N-Fe-B alloys.
d-Pr-Fe-B-based alloy, Nd-Dy-Fe-B-based alloy, Ce-Nd-Fe-B-based alloy, Ce-Pr-Nd-
Fe-B alloys, in which some of Fe is Co, N
and those substituted with another transition metal such as i.

[0036] Typical examples of the Sm-Fe-N based alloy, Sm ₂ Fe ₁₇ was prepared by nitriding the Sm ₂ Fe ₁₇ alloy
Sm-Zr-Fe-C having N ₃ and TbCu ₇ type phase as main phase
o-N based alloys. However, these Sm-Fe
In the case of an -N-based alloy, N is generally introduced as an interstitial atom by preparing a quenched ribbon, subjecting the obtained quenched ribbon to an appropriate heat treatment, and nitriding.

As R (rare earth element), Y, La, C
e, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
Examples include y, Ho, Er, Tm, Yb, Lu, dymium, and misch metal, and one or more of these may be included.

Examples of the TM include Fe, Co, Ni and the like, and one or more of these can be contained.
Among them, it is particularly preferable to use an R-TM-B alloy.

By using the magnet powder having such an alloy composition, particularly excellent magnetic properties can be obtained when the obtained kneaded material is used for manufacturing a bonded magnet described later.

[Constitutional Structure] The magnet powder may be composed of a composite structure having a soft magnetic phase and a hard magnetic phase.

This composite structure (nanocomposite structure)
Is a pattern (model) in which the soft magnetic phase 10 and the hard magnetic phase 11 are, for example, as shown in FIG. 1, FIG. 2 or FIG.
And the thickness and particle size of each phase exist at the nanometer level. Then, the soft magnetic phase 10 and the hard magnetic phase 11 are adjacent to each other (including the case where they are adjacent via the grain boundary phase), and a magnetic exchange interaction occurs.

The average crystal grain size of each phase is preferably from 1 to 100 nm, more preferably from 5 to 50 nm. If the average crystal grain size of each phase is less than the lower limit, the influence of exchange interaction between crystal grains becomes too strong, magnetization reversal becomes easy, and coercive force may deteriorate. on the other hand,
If the average crystal grain size of each phase exceeds the above upper limit, coarsening of the crystal grain size and the influence of exchange interaction between the crystal grains become weaker, so that the magnetic flux density, coercive force, squareness, and maximum energy The product may deteriorate.

It should be noted that the patterns shown in FIGS. 1 to 3 are merely examples, and the present invention is not limited to these patterns.
In the pattern shown in (1), the soft magnetic phase 10 and the hard magnetic phase 11 may be reversed.

Since the direction of the magnetization of the soft magnetic phase is easily changed by the action of an external magnetic field, if it is mixed with the hard magnetic phase, the magnetization curve of the entire system has a step in the second quadrant of the BH diagram. It becomes a "snake-shaped curve". However, when the size of the soft magnetic phase is sufficiently small, the magnetization of the soft magnetic material is sufficiently strongly restricted by the coupling with the magnetization of the surrounding hard magnetic material, and the entire system behaves as a hard magnetic material.

The magnet having such a composite structure (nanocomposite structure) mainly has the following features 1) to 5).
have.

1) In the second quadrant of the BH diagram (JH diagram),
The magnetization reversibly springs back (also referred to as a "spring magnet" in this sense). 2) Good magnetization and can be magnetized with a relatively low magnetic field. 3) The temperature dependence of the magnetic properties is smaller than in the case of the hard magnetic phase alone. 4) Changes in magnetic properties with time are small. 5) The magnetic properties do not deteriorate even when finely pulverized.

In the above-described alloy composition, the hard magnetic phase and the soft magnetic phase are as follows, for example.

Hard magnetic phase: R ₂ TM ₁₄ B system Soft magnetic phase: TM (particularly α-Fe, α- (Fe, C
o)) or the compound phase of TM and B

[Production of Magnet Powder] The magnet powder may be produced by any method, but is preferably produced by quenching a molten alloy. The molten alloy is quenched and solidified. More preferably, it is produced by pulverizing the quenched ribbon (ribbon) obtained. Hereinafter, an example of the method will be described.

FIG. 4 is a perspective view showing an example of the configuration of an apparatus for manufacturing a magnet material by a quenching method using a single roll (a quenched thin strip manufacturing apparatus). FIG. FIG. 4 is a cross-sectional side view showing a state near a collision site with the vehicle.

As shown in FIG. 4, a quenched ribbon manufacturing apparatus 1
Includes a cylindrical body 2 capable of storing a magnet material, and a cooling roll 5 that rotates in the direction of arrow 9A in the figure with respect to the cylindrical body 2. A nozzle (orifice) 3 for injecting molten metal of a magnet material (alloy) is formed at a lower end of the cylindrical body 2.

On the outer periphery of the cylindrical body 2 near the nozzle 3,
A heating coil 4 is arranged, and the inside of the cylinder 2 is heated (induction heating) by applying, for example, a high frequency to the coil 4 to bring the magnet material in the cylinder 2 into a molten state.

The cooling roll 5 comprises a base 51 and a surface layer 52 forming a peripheral surface 53 of the cooling roll 5.

The constituent material of the base 51 may be the same material as the surface layer 52 and may be integrally formed, or may be formed of a different material from the surface layer 52.

The constituent material of the base portion 51 is not particularly limited, but is made of a metal material having a high thermal conductivity such as copper or a copper-based alloy so that the heat of the surface layer 52 can be dissipated more quickly. Is preferred.

The surface layer 52 is preferably made of a hard material from the viewpoint of durability. Also, the surface layer 52
Is preferably made of a material having a thermal conductivity equal to or lower than that of the base 51. Specific examples of the surface layer 52 include, for example, Zr, Sb, Ti, Ta, P
Examples include a thin metal layer or metal oxide layer of d, Pt, or an alloy containing these, a ceramic, and the like. As ceramics, for example, Al ₂ O ₃ , SiO ₂ , TiO ₂ , T
oxide ceramics such as i ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , barium titanate and strontium titanate; AlN;
Si ₃ N ₄ , TiN, BN, ZrN, HfN, VN, Ta
Nitride ceramics such as N, NbN, CrN, Cr ₂ N, graphite, SiC, ZrC, Al ₄ C ₃ , CaC
_2. Non-oxide ceramics such as carbide ceramics such as WC, TiC, HfC, VC, TaC, NbC,
Alternatively, a composite ceramic in which two or more of these are arbitrarily combined is exemplified. Among these, it is particularly preferable to include a nitride-based ceramic.

The quenched ribbon manufacturing apparatus 1 is installed in a chamber (not shown), and operates in a state where the chamber is preferably filled with an inert gas or other atmospheric gas. In particular, the atmosphere gas is preferably an inert gas such as an argon gas, a helium gas, or a nitrogen gas in order to prevent the quenched ribbon 8 from being oxidized.

In the quenched ribbon manufacturing apparatus 1, a magnet material (alloy) is put in a cylindrical body 2, heated by a coil 4 and melted.
When the molten metal 6 is discharged from the nozzle 3, as shown in FIG. 5, the molten metal 6 collides with the peripheral surface 53 of the cooling roll 5, forms a paddle (pool) 7, and then rotates around the rotating cooling roll 5. It is rapidly cooled and solidified while being dragged by the surface 53, and the quenched ribbon 8 is formed continuously or intermittently. The roll surface 81 of the quenched ribbon 8 formed in this way eventually separates from the peripheral surface 53 and advances in the direction of arrow 9B in FIG. In FIG. 5, the solidification interface 71 of the molten metal is indicated by a dotted line.

The suitable range of the peripheral speed of the cooling roll 5 varies depending on the composition of the molten alloy, the wettability of the peripheral surface 53 to the molten metal 6, and the like.
It is preferably 60 m / sec, more preferably 5 to 40 m / sec. If the peripheral speed of the cooling roll 5 is too slow, the thickness t of the quenched ribbon 8 increases, depending on the volume flow rate of the quenched ribbon 8 (the volume of the molten metal discharged per unit time), and the crystal grain size increases. Conversely, if the peripheral speed of the cooling roll 5 is too high, most of the cooling roll 5 has an amorphous structure,
In either case, improvement in magnetic properties cannot be expected even if heat treatment is applied thereafter.

The obtained quenched ribbon 8 may be subjected to at least one heat treatment in order to promote recrystallization of the amorphous structure and homogenize the structure. The condition of this heat treatment is, for example, at 400 to 900 ° C.
It can be about 0.5 to 300 minutes.

The heat treatment is performed under vacuum or reduced pressure (for example, 1 × 10 ⁻¹ to 1 × 1) in order to prevent oxidation.
0 ^-6 Torr), or nitrogen gas, argon gas, such as inert gas such as helium gas, preferably carried out in a non-oxidizing atmosphere.

The quenched ribbon 8 is pulverized to obtain magnet powder. The method of pulverization is not particularly limited, and the pulverization can be performed using various pulverizing devices such as a ball mill, a vibration mill, a jet mill, and a pin mill, and a crushing device. In this case, the pulverization is performed under vacuum or reduced pressure (for example, 1 × 10 ⁻¹ to 1 × 10 ⁻⁶ T) to prevent oxidation.
orr) or in a non-oxidizing atmosphere such as in an inert gas such as nitrogen gas, argon gas, helium gas or the like.

The obtained magnet powder may be subjected to a heat treatment for the purpose of, for example, removing the influence of the strain introduced by pulverization and controlling the crystal grain size. The condition of this heat treatment is, for example, 350 to 850 ° C.
Thus, it can be set to about 0.5 to 300 minutes.

This heat treatment is performed under vacuum or reduced pressure (for example, 1 × 10 ⁻¹ to 1 × 1) in order to prevent oxidation.
0 ^-6 Torr), or nitrogen gas, argon gas, such as inert gas such as helium gas, preferably carried out in a non-oxidizing atmosphere.

In particular, when N is contained in the alloy composition,
Is introduced by, for example, a nitriding treatment. This nitriding treatment is performed, for example, in a nitrogen gas atmosphere at 350 to 650.
The heat treatment can be carried out at a temperature of about 0.1 to 200 hours. The heat treatment (nitriding treatment) may be performed for the purpose of controlling the crystal grain size as described above.

The nitriding treatment may be performed after the quenched ribbon is pulverized, or may be performed before the pulverization.

The introduction of N is not limited to the heat treatment (nitriding). For example, N may be introduced by a solid phase reaction using ammonia or a nitrogen compound as a raw material.

At this time, the magnet powder is pulverized so that its average particle size is larger than the final average particle size in the kneaded material described later. As a result, the resulting magnetic powder has a small specific surface area per unit weight, and is unlikely to cause a decrease in magnetic properties due to oxidation or the like. As a result, the magnetic properties of the resulting bonded magnet are excellent. Further, since it is not necessary to finely crush the quenched ribbon 8, the manufacturing process of the magnet powder can be simplified.

The average particle size of the magnetic powder thus produced is not particularly limited, but is preferably from 10 to 1200 μm, more preferably from 25 to 500 μm, and further preferably from 40 to 250 μm. preferable.

If the average particle size of the magnet powder is less than the above lower limit, the specific surface area per unit weight of the magnet powder becomes large, so that the magnetic properties of the magnet powder are liable to be deteriorated due to oxidation deterioration and the like. Further, since the activity of the powder is increased, there is a case where handling of the magnet powder becomes difficult, for example, the risk of ignition or the like is increased.

On the other hand, when the average particle size of the magnet powder exceeds the above upper limit, the powder having a large particle size may not be sufficiently pulverized at the time of kneading and powder having a large particle size may remain, and the moldability of the bonded magnet may be reduced. is there. For this reason, it becomes difficult to increase the content of the magnet powder in the bonded magnet, and sufficient magnetic properties may not be obtained. Further, the mechanical strength and the like of the obtained bonded magnet may be reduced.

In order to obtain better moldability during molding of the bonded magnet, 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 be reduced, and as a result, when the content of the magnet powder in the bonded magnet is the same, the density and mechanical strength of the bonded magnet can be further increased. And the magnetic properties can be further improved.

Although the single-roll method has been described as an example of the quenching method, a twin-roll method may be employed. In addition, it may be manufactured by an atomizing method such as a gas atomizing method, a rotating disk method, a melt extraction method, or the like. Such a quenching method is effective for improving the magnetic properties of the bonded magnet, particularly the coercive force, since the metal structure (crystal grains) can be refined. Further, a magnet powder manufactured by a mechanical alloying (MA) method or the like can also be used.

For the production of a bonded magnet described later, one or more of the above-mentioned magnet powders can be used in combination.

[Binder] Next, the binder will be described.

The binder may be any binder, but preferably contains a thermoplastic resin or a thermosetting resin.

Examples of the thermoplastic resin include polyamide (eg, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), thermoplastic polyimide , Liquid crystal polymers such as aromatic polyesters, polyphenylene oxide, polyphenylene sulfide, polyethylene, polypropylene, polyolefins such as ethylene-vinyl acetate copolymer, modified polyolefins, polyesters such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, and the like. Ether, polyetheretherketone, polyetherimide, polyacetal, etc.
Alternatively, copolymers, blends, polymer alloys, and the like mainly containing these may be used, and one or more of these may be used as a mixture. In addition, a mixture of similar resins having different molecular weights, melting points, and the like can also be used.

Among these, polyamides and liquid crystal polymers and polyphenylene sulfides are preferred because they have particularly excellent moldability and high mechanical strength, and therefore, from the viewpoint of improving heat resistance. These thermoplastic resins are also excellent in kneadability with magnet powder.

Depending on the type and copolymerization of such a thermoplastic resin, it is possible to select a wide range of thermoplastic resins, for example, those giving importance to moldability and those giving importance to heat resistance and mechanical strength. There is an advantage.

On the other hand, examples of the thermosetting resin include various epoxy resins such as bisphenol type, novolak type, and naphthalene type, phenol resin, urea resin, melamine resin, polyester (unsaturated polyester) resin, polyimide resin, and silicone resin. , Polyurethane resins, and the like, and one or more of these can be used as a mixture. In addition, a mixture of similar resins having different molecular weights, melting points, and the like can also be used.

Of these, the moldability is particularly excellent, the mechanical strength is high, and the heat resistance is excellent.
Epoxy resins, phenol resins, polyimide resins and silicone resins are preferred, and epoxy resins are particularly preferred.
In addition, these thermosetting resins are excellent in kneading property and uniformity of kneading with the magnet powder in a softened state.

The thermosetting resin used (uncured)
May be liquid at room temperature or solid (powder) as long as a softened state can be obtained before curing.

When a thermosetting resin is used, a curing agent may be contained in the binder. Examples of the curing agent include amine-based and acid anhydride-based curing agents.
Among them, imidazole-based compounds, which are one type of amine-based compounds, are particularly preferable.

In the binder, for example, various additives (antioxidants, lubricants, thinners, curing accelerators, etc.)
And other components other than the resin.

[Kneading of Magnet Powder and Binder] A kneaded product is manufactured by kneading a material containing the above-described magnet powder and binder.

In the present invention, the kneading is performed while pulverizing the magnet powder (grain size adjustment) so that the average particle size of the magnet powder after the kneading is smaller than the average particle size of the magnet powder in the material before kneading. While doing). That is, the magnet powder is pulverized at the time of kneading so that the final (target) is obtained.
It will have an average particle size.

As described above, when grinding the magnet powder while kneading the materials, the binder covers the magnet powder,
The contact between the magnet powder and the air is extremely reduced, and oxidation degradation or the like is unlikely to occur in a portion or the like that newly becomes the surface of the magnet powder. For this reason, the bonded magnet manufactured using the kneaded material obtained in this way has higher magnetic characteristics than the bonded magnet manufactured using the finely ground magnet powder in advance.

Also, by grinding the magnet powder while kneading the material, the binder immediately comes into contact with the new surface of the magnet powder, so that there is no intervening substance such as moisture between the magnet powder and the binder. Adhesion with the binder is improved. As a result, the surface of the magnet powder is sufficiently coated with the binder.

As a result, the fluidity of the obtained kneaded material is improved, and the moldability into a bonded magnet becomes excellent. That is, even when the amount of the binder in the material is relatively small, the obtained kneaded material has excellent moldability, and a bonded magnet having a desired shape can be easily manufactured.

The resulting bonded magnet is excellent in corrosion resistance, heat resistance, mechanical strength, and the like.

As described above, in the present invention, kneading is performed so that the average particle diameter of the magnet powder after the kneading is smaller than the average particle diameter in the material before kneading. When the average particle diameter is D ₀ [μm] and the average particle diameter of the magnetic powder after the kneading is D ₁ [μm], the following formula (I) is obtained.
Is preferably satisfied.

0.1 ≦ D ₁ / D ₀ ≦ 0.9 (I) It is more preferable that the formula (II) is satisfied instead of the formula (I), and that the formula (III) is satisfied. Is more preferred.

0.2 ≦ D ₁ / D ₀ ≦ 0.8 (II) 0.3 ≦ D ₁ / D ₀ ≦ 0.6 (III) D ₁ / D ₀ is such that When the value is within the range, the moldability of the bonded magnet becomes particularly excellent. Further, the corrosion resistance, heat resistance, mechanical strength and the like of the obtained bonded magnet are improved.

The average particle diameter D ₁ of the magnet powder after completion of the kneading is as follows:
Although not particularly limited, it is preferably from 1 to 500 μm, more preferably from 20 to 200 μm.

If the average particle diameter D ₁ of the magnet powder after the completion of the kneading is less than the above lower limit, the energy required for kneading becomes large and the kneading tends to be excessive. As a result, a decomposition reaction or the like of the resin proceeds, and the moldability into a bonded magnet and the magnetic properties of the obtained bonded magnet may be reduced.

On the other hand, the average particle diameter D of the magnet powder after the kneading is completed.
_{If 1} exceeds the above upper limit, the effect of pulverizing the magnet powder while kneading is low, and the moldability into a bonded magnet may be reduced. For this reason, it becomes difficult to increase the content of the magnet powder in the bonded magnet, and sufficient magnetic properties may not be obtained in some cases. Moreover, the corrosion resistance, heat resistance, mechanical strength, and the like of the obtained bonded magnet may be reduced.

The content of the magnet powder in the material is not particularly limited, but is preferably from 50 to 95 vol%, more preferably from 60 to 90 vol%. When the content of the magnet powder in the material is less than the lower limit, when the obtained kneaded material is used for manufacturing a bonded magnet,
There is a possibility that the magnetic properties as a bonded magnet cannot be sufficiently obtained. On the other hand, if the content of the magnet powder in the material exceeds the upper limit, the content of the binder becomes relatively small, and the mechanical strength of the bonded magnet may be reduced.

It is preferable that the material contains an antioxidant. This makes it possible to more effectively prevent the oxidative deterioration of the magnet powder during kneading and the like, and as a result, the resulting bonded magnet has particularly excellent magnetic properties and the like.

As the antioxidant, any antioxidant can be used as long as it can prevent or suppress the oxidation of the magnet powder and the like. Examples thereof include amine compounds, amino acid compounds, nitrocarboxylic acids, hydrazine compounds, cyanide compounds, sulfide compounds and the like. Chelating agents that form chelating compounds for metal ions, particularly Fe components, such as substances.

When such an antioxidant is added, the content of the antioxidant in the material should be 0.2 to 3 wt%.
And more preferably 0.5 to 2 wt%.

In the material, if necessary, for example, a plasticizer (for example, a fatty acid salt such as zinc stearate,
Various additives such as fatty acids such as oleic acid), lubricants (eg, silicone oil, various waxes, fatty acids, various inorganic lubricants such as alumina, silica, titania), and other molding aids can be added.

The ratio (D ₁ / D ₀ ) of the average particle diameter of the magnet powder before and after kneading the materials can be determined, for example, by adjusting various conditions such as energy given to the materials and kneading time during kneading. , Can be controlled.

The kneading is performed at a rate of 0.07 to 1 / L of the material.
It is preferably performed by applying energy of 3.5 kWh, and more preferably performed by applying energy of 0.5 to 2 kWh.

However, the kneading energy E [kWh / L] per liter of the material is E ₁ [kWh], the power consumption of the kneading apparatus during kneading, E ₀ [kWh], the power consumption of the kneading apparatus during idling. Assuming that the volume of the material is V [L], it is obtained as E = (E ₁ −E ₀ ) / V.

By kneading the material by giving such energy, the magnet powder in the material is appropriately pulverized while being covered with the binder, and has a suitable particle size distribution. For this reason, the obtained kneaded material contains fine magnet powder with little oxidation deterioration or the like. Therefore, a bonded magnet manufactured using such a kneaded material has excellent magnetic properties.

Further, by applying the energy as described above and kneading the materials, the adhesion between the magnet powder and the binder is also improved. For this reason, the obtained kneaded material has excellent moldability into a bonded magnet. Further, a bonded magnet manufactured using such a kneaded material has excellent corrosion resistance, heat resistance, mechanical strength, and the like.

The kneading energy E per liter of the material is
By setting [kWh / L] to a value in such a range, for example, even when the binder is composed of two or more components, the obtained kneaded material is sufficiently uniformly mixed with the magnetic powder and the binder. They can be mixed.

A kneading apparatus is usually used for kneading the materials. Examples of the kneading device for performing kneading include a kneader or a batch type triaxial roll, a continuous twin screw extruder, a continuous twin screw roll, a wheel mixer, a blade type mixer and the like. Twin screw extruders and continuous twin screw rolls are preferred. By using such a kneading apparatus, the production process can be easily made into a line, and the productivity of the kneaded material and the bonded magnet is improved.

The kneading is preferably performed at a temperature higher than the softening point of the binder. As a method for measuring the softening point, the ring and ball method defined by JIS K 7234, AS
The Mettler method specified by TMD3461 is known. In particular, when the softening point of the binder is T ° C., the kneading is preferably performed at T to (T + 100) ° C. However, when the binder contains a thermosetting resin, the upper limit of the temperature of the material during kneading is preferably lower than the temperature at which the binder starts to cure. By kneading the materials at such a temperature, the adhesion between the magnet powder and the binder in the kneaded material is further improved.

When the binder contains two or more components, the term “softening point” as used herein refers to the softening point of the component having the softening point measured for the mixed binder.

The kneading is preferably performed in an atmosphere of an inert gas such as an argon gas, a helium gas or a nitrogen gas in order to prevent the magnet powder from being oxidized and deteriorated. The kneaded material thus obtained is, for example, if necessary,
It may be pelletized. The average particle size of the pellets is, for example, about 0.05 to 10 mm.

[Production of Bonded Magnet] The kneaded product (including pellets) produced as described above is molded according to the purpose to produce a bonded magnet.

As described above, the kneaded material contains magnet powder which is less oxidatively degraded and is finely pulverized. Therefore, the bonded magnet obtained by molding such a kneaded material has high magnetic properties.

Examples of the method for forming a bonded magnet include compression molding (press molding), extrusion molding, injection molding and the like. According to these molding methods, the kneaded material is molded into a desired shape in a magnetic field or without a magnetic field. When the binder contains a thermosetting resin, it is cured by heating or the like after molding.

Here, of the three molding methods, compression molding can be performed with a smaller amount of binder than other methods, so that the content of magnet powder in the bonded magnet can be increased. This is advantageous for improving the magnetic properties.

However, in the conventional bonded magnet, particularly when the amount of the binder is reduced, unevenness occurs and the adhesiveness between the binder and the magnet powder is reduced. There were problems such as a decrease in corrosion resistance, heat resistance, and mechanical strength of the magnet.

On the other hand, in the present invention, as described above, the magnet powder and the binder are uniformly mixed without sufficient unevenness, and the surface of the magnet powder is coated with the binder with sufficient adhesion. Therefore, even when the amount of the binder is small, the kneaded material has excellent moldability. Further, the bonded magnet obtained by molding the kneaded material has excellent corrosion resistance, heat resistance, mechanical strength, and the like.

Therefore, according to the present invention, even when the amount of the binder in the kneaded material is small, excellent moldability can be obtained. Can be included.

[0119] The density of the bonded magnet ρ is not particularly limited, and is preferably about 4.0~8.0Mg / m ^3, more preferably about 5.5~8.0Mg / m ^3.

The shape and dimensions of the bonded magnet are not particularly limited. For example, the shape of the bonded magnet may be any shape such as a column, a prism, a cylinder (ring), an arc, a flat plate, and a curved plate. And any size, from large to very small.

The bond magnet of the present invention preferably has a coercive force (intrinsic coercive force at room temperature) H _cJ of about ₄₀₀ to 1500 kA / m, more preferably about 500 to 1000 kA / m. When the coercive force is less than the lower limit,
For example, when a bonded magnet is used for a motor, the demagnetization when a reverse magnetic field is applied becomes remarkable depending on the use or the like, and the heat resistance at high temperatures is poor. On the other hand, when the coercive force exceeds the upper limit, the magnetization decreases. Therefore, by _setting the coercive force _HcJ to a value within the above range, even when a sufficient magnetizing magnetic field cannot be obtained in a case where a bonded magnet (particularly, a cylindrical magnet) is multipolar magnetized, etc. Good magnetization can be achieved, sufficient magnetic flux density can be obtained, and a high-performance bonded magnet, particularly a bonded magnet for motors can be provided.

The bonded magnet preferably has a maximum magnetic energy product (BH) _max of 50 kJ / m ³ or more, more preferably 60 kJ / m ³ or more, and more preferably 75 kJ / m ³ or more.
More preferably, it is kJ / m ³ or more. If the maximum magnetic energy product (BH) _{max of the} bonded magnet is less than 50 kJ / m ³ , when used for a motor, sufficient torque cannot be obtained depending on its type and structure.

It is preferable that the absolute value of the irreversible demagnetization rate (initial demagnetization rate) of the bonded magnet when it is kept in an environment of 100 ° C. × 1 hour and then returned to room temperature is 8% or less. More preferably, it is 5% or less. Thereby, a bonded magnet having excellent thermal stability (heat resistance) can be obtained.

[0124]

Next, specific examples of the present invention will be described.

(Example 1) In the following manner,
Alloy composition _{(Nd 0.8 Pr 0.2) 8.9 Fe} bal. Co 7 .0 B
A magnet powder represented by _5.8 Dy _0.8 Mn _0.5 was obtained.

First, Nd, Pr, Fe, Co, B, Dy
Each raw material of Mn and Mn was weighed to cast a mother alloy ingot, and a sample was cut out from the ingot.

A quenched ribbon manufacturing apparatus 1 having the configuration shown in FIGS. 4 and 5 was prepared, and the sample was placed in a quartz tube provided with a nozzle (circular orifice: orifice diameter 0.6 mm) 3 at the bottom. After evacuating the inside of the chamber containing the quenched ribbon manufacturing apparatus 1, an inert gas (argon gas) is used.
Was introduced into the atmosphere at a desired temperature and pressure.

As the cooling roll 5, one having a surface layer 52 made of VN and having a thickness of about 7 μm on the outer periphery of a copper base 51 (diameter 200 mm) was used.

Thereafter, the ingot sample in the quartz tube was melted by high-frequency induction heating, and the injection pressure of the molten metal (the sum of the internal pressure of the quartz tube and the pressure applied in proportion to the liquid level in the cylinder 2 and the atmosphere) Pressure difference) and the peripheral speed of the cooling roll were adjusted to produce a quenched ribbon. The average thickness of the quenched ribbon obtained at this time was 18 μm.

After the obtained quenched ribbon was roughly pulverized, it was subjected to a heat treatment at 680 ° C. for 300 seconds in an argon gas atmosphere to obtain a magnet powder. The average particle size (D
₀ ) was 167.8 μm. The average particle size (D ₀ ) of the magnet powder was determined by classifying the magnet powder with a test sieve.
It was determined from the weight.

In order to analyze the phase constitution of the obtained magnet powder, a diffraction angle of 20 ° to 60 ° using Cu-Kα was used.
X-ray diffraction was performed at. From the diffraction pattern, the diffraction peaks of the R ₂ (Fe.Co) ₁₄ B type phase as the hard magnetic phase and the α- (Fe, Co) type phase as the soft magnetic phase can be confirmed.
Observation by a transmission electron microscope (TEM) confirmed that a composite structure (nanocomposite structure) was formed.

Using the magnetic powder thus obtained, 10 kinds of kneaded materials (sample No.
1 to No. 10) was manufactured.

Magnet powder: 84 vol%, cresol novolak type epoxy resin (softening point: 83.5 ° C.): 15.
3 vol% and 2-methylimidazole (curing agent):
0.6 vol% and wax (lubricant): 0.1 vol
% Was put into the kneading apparatus. As a kneading device, a continuous twin-screw roll with grooves or a continuous twin-screw extruder was used.

Thereafter, the materials were kneaded in the air.
The material temperature during kneading was 100 ° C. At this time, as shown in Table 1, the kneading energy E per liter of the material was varied from 0.07 to 3.5 kWh / L to thereby obtain 10 kinds of kneaded materials (sample Nos. 1 to N).
o. 10) was manufactured.

The sample No. Eleven kneaded materials were produced as follows. Magnet powder: 84 vol%, cresol novolak type epoxy resin (softening point 83.5 ° C): 15.3 vol%
And 2-methylimidazole (curing agent): 0.6 vol
% And a wax (lubricant): 0.1 vol%, and acetone were charged into a kneading apparatus. In addition, a raikai machine was used as a kneading device.

Then, with the material temperature kept at 80 ° C.
The kneaded material was obtained by kneading the materials and evaporating the acetone. At this time, the kneading energy E per liter of the material was 0.003 kWh. The kneading of the materials was performed in the air.

The sample No. 1 was prepared except that the content of the magnet powder in the material was 80 vol%. 8 in the same manner as in the kneaded material of Sample No. 8. Twelve kneaded materials were produced.

[0138] In addition, except that the content of the magnet powder in the material was set to 80 vol%, the sample No. In the same manner as in the kneaded material of Sample No. 11, Thirteen kneaded materials were produced.

The sample No. Fourteen kneaded materials were produced as follows. After coarsely pulverizing the above-described quenched ribbon, a heat treatment is performed at 680 ° C. for 300 seconds in an argon gas atmosphere, and further pulverized in the air using a pulverizer (tilsonator) to obtain an average particle diameter (D _0). ) 76.
2 μm magnet powder was obtained.

Magnet powder: 84 vol%, cresol novolak type epoxy resin (softening point: 83.5 ° C.): 15.
3 vol% and 2-methylimidazole (curing agent):
0.6 vol% and wax (lubricant): 0.1 vol
%, And acetone were charged into a kneading apparatus. In addition, a raikai machine was used as a kneading device.

Then, with the material temperature kept at 80 ° C.
The kneaded material was obtained by kneading the materials and evaporating the acetone. At this time, the kneading energy E per liter of the material was 0.003 kWh. The kneading of the materials was performed in the air. Table 1 summarizes the production conditions of these kneaded materials.

Further, a part of each kneaded material thus obtained was taken out, and the average particle diameter (D ₁ ) of the magnet powder in the kneaded material was measured as follows.

A sufficient amount of acetone was added to the partially removed kneaded material to dissolve the binder, wax and curing agent. Thereafter, the solution was filtered to separate the magnet powder. After sufficiently washing and drying this magnet powder, it was classified using a sieve, and the weight average particle size was measured. Note that these operations were performed in an argon gas atmosphere.
For each sample, indicating the average particle diameter D ₁ of the after kneading in Table 1.

[0144]

[Table 1]

Next, the sample no. 1 to No. Using the kneaded material of No. 14, 200 columnar bonded magnets were manufactured as follows.

First, the kneaded material obtained as described above was pulverized into pellets having an average particle size of about 0.5 mm, and the pellets were weighed and filled into a mold of a press device, and were cooled at room temperature. Pressure of 140 kg / cm ² by bi-directional pressing
For compression molding (in the absence of a magnetic field). Release from molding die,
The epoxy resin was heated and cured at 70 ° C. × 2 hours to obtain a cylindrical bonded magnet having a diameter of 10 mm and a height of 7 mm.

In the same manner, for sample no. 1 to N
o. Using the kneaded material of No. 14, 30 mm outside diameter x 28 m inside diameter
200 cylindrical (ring-shaped) bonded magnets each measuring mx 5 mm in height were manufactured.

Note that the sample No. 1 to No. 10, N
o. 12-No. While the bonded magnet according to No. 14 could be manufactured with excellent moldability, sample No. 1
In the bonded magnet according to No. 1, a rough portion was observed near the center in the height direction.

The bonded magnets thus obtained were measured and evaluated as described below.

<Evaluation of Magnetic Characteristics> The columnar bonded magnet obtained as described above was subjected to a magnetic field strength of 3.2 MA.
/ M, and a maximum applied magnetic field of 2.0 was measured with a direct current magnetic flux meter (manufactured by Toei Kogyo Co., Ltd., TRF-5BH).
Magnetic properties (intrinsic coercive force H _cJ , maximum magnetic energy product (BH) _max ) were measured at MA / m. The temperature at the time of measurement was 2
It was 3 ° C (room temperature).

<Evaluation of Heat Resistance> Next, a heat resistance test was performed. The heat resistance of the columnar bonded magnet is 100 ° C x
After being kept in an environment for one hour, the irreversible demagnetization rate (initial demagnetization rate) when the temperature was returned to room temperature was measured and evaluated. The smaller the absolute value of the irreversible demagnetization rate (initial demagnetization rate), the better the heat resistance (thermal stability).

<Evaluation of Corrosion Resistance> Next, a corrosion resistance test was performed. Cylindrical bonded magnets (200 each) at 80 ° C, 8
It was put in a constant temperature and humidity chamber of 0 RH% and left for 300 hours. After standing, the rusting rate was determined by counting the number of rusting bond magnets.

<Evaluation of Molded Appearance> The cylindrical (ring-shaped) bonded magnets were evaluated for their molded appearance in accordance with the following four-grade criteria. A: The appearance is very good. ：: The appearance is excellent. Δ: The appearance is slightly inferior. X: Poor appearance.

<Evaluation of mechanical strength> Cylindrical (ring)
Of these bonded magnets (200 each) were measured for their radial crushing strength. The radial crushing strength is measured according to JIS Z 250
7 was carried out. The density ρ of each bonded magnet was measured by the Archimedes method.

Table 2 shows the results. The mechanical strength of each bonded magnet is shown in Sample No. 14 shows the relative strength when the radial crushing strength of the bonded magnet according to No. 14 is set to 100.

[0156]

[Table 2]

As is clear from Table 2, the sample No.
1 to No. 10, No. 12 (all of the present invention) have magnetic properties (specific coercive force H _cJ ,
Excellent in maximum magnetic energy product (BH) _max ), heat resistance (thermal stability), corrosion resistance, molded appearance, and mechanical strength. Among them, sample N having a large content of magnet powder
o. 1 to No. In the bonded magnet according to No. 10, particularly excellent magnetic properties are obtained.

On the other hand, the sample No. 11, No.
Bond magnet No. 13 (comparative example) is inferior in heat resistance, corrosion resistance and mechanical strength. This corresponds to sample no. 11,
No. In the bonded magnet according to No. 13, since the magnet powder is not pulverized at the time of kneading, the average particle size (D ₁ ) of the magnet powder after kneading is large, and the adhesion between the magnet powder and the binder is insufficient. It is thought that it is. Moreover, in this way, if the average particle diameter D ₁ of the magnet powder after kneading is large, it is difficult to increase the content of the magnetic powder in the bonded magnet. Therefore, in the sample No. having a large content of the magnet powder, The bonded magnet of No. 13 is inferior in the molded appearance and in spite of the large content of the magnet powder, is also inferior in the magnetic properties.

The sample No. The bonded magnet of Comparative Example 14 (Comparative Example) is excellent in molding appearance, but has magnetic properties (specific coercivity H _cJ , maximum magnetic energy product (B
H) _max ), poor heat resistance (thermal stability), corrosion resistance and mechanical strength.

The sample No. The inferior magnetic properties of the bonded magnet No. 14 are considered to be due to the following reasons.

Sample No. The kneaded product of No. 14 was prepared by previously pulverizing magnet powder (average particle diameter (D ₀ ): 76.2 μm).
m). For this reason, the magnetic properties of this magnet powder are deteriorated due to oxidation deterioration or the like. Therefore, the sample No. manufactured using such a magnet powder was used. It is considered that the bonded magnet No. 14 also has low magnetic properties.

The sample No. The bond magnet according to No. 14 is inferior in heat resistance (thermal stability), corrosion resistance and mechanical strength because the kneading of the materials was carried out under such conditions that the magnet powder was not crushed. This is probably because the adhesion to the binder was insufficient.

(Example 2) The alloy composition was (Sm _0.75 Zr _0.25 ) ₁₀ Fe _bal Co _8.5 Ti by the method described below.
A magnet powder represented by _1.0 Mn _1.0 N ₁₂ B _1.5 was obtained.

First, Sm, Zr, Fe, Co, Ti, M
n, B raw materials are weighed to cast a mother alloy ingot,
A sample was cut from this ingot.

A quenched ribbon manufacturing apparatus 1 having the structure shown in FIGS. 4 and 5 was prepared, and the sample was placed in a quartz tube provided with a nozzle (circular orifice) 3 at the bottom. After evacuating the inside of the chamber in which the quenched ribbon manufacturing apparatus 1 was housed, an inert gas (argon gas, helium gas) was introduced to obtain an atmosphere of a desired temperature and pressure.

After that, the ingot sample in the quartz tube was melted by high-frequency induction heating, and the injection pressure of the molten metal (the sum of the internal pressure of the quartz tube and the pressure applied in proportion to the liquid level in the cylinder 2) A quenched ribbon was prepared by adjusting the peripheral pressure of the cooling roll and the peripheral pressure of the cooling roll.

After the obtained quenched ribbon was roughly pulverized, a heat treatment was performed at 720 ° C. for 15 minutes in an argon gas atmosphere. Furthermore, in order to adjust the particle size, a crusher (raikai machine)
And pulverized in an argon gas to obtain an average particle size (D ₀ ) 1
A powder of 17.3-305.0 μm was obtained.

The thus obtained powder was subjected to a heat treatment (nitriding treatment) at 450 ° C. for 20 hours in a nitrogen gas atmosphere to obtain a magnet powder having the above composition.

To analyze the phase constitution of the obtained magnet powder, the diffraction angle (2θ) was set to 20 using Cu-Kα.
X-ray diffraction was performed in the range of ° to 80 °. From the diffraction pattern, it was confirmed that the TbCu ₇ type phase was present as the main phase.

Using these magnet powders, seven kinds of kneaded materials (sample Nos. 15 to 2) were prepared as follows.
1) was manufactured.

Magnet powder: 84 vol%, cresol novolak type epoxy resin (softening point: 83.5 ° C.): 15.
3 vol% and 2-methylimidazole (curing agent):
0.6 vol% and wax (lubricant): 0.1 vol
% Was put into the kneading apparatus. As a kneading device, a continuous twin-screw roll with grooves or a continuous twin-screw extruder was used.

Thereafter, the material temperature was set to 100 ° C., and the materials were kneaded to obtain seven kinds of kneaded materials (sample No. 1).
15-No. 21) was prepared. At this time, the kneading energy E per liter of the material was 0.07 as shown in Table 3.
Various changes were made between ５5.0 kWh / L. The kneading of the materials was performed in a nitrogen gas atmosphere. Table 3 summarizes the production conditions of these kneaded materials.

Further, the average particle size (D ₁ ) of the magnet powder in the kneaded material (sample Nos. 15 to 21) thus obtained was measured in the same manner as in Example 1. Table 3 shows the average particle size (D ₁ ) of each sample after kneading.

[0174]

[Table 3]

Using the kneaded material thus obtained,
In the same manner as in Example 1, a cylindrical bond magnet and a cylindrical bond magnet were manufactured. The sample No. 15-N
o. All of the bonded magnets No. 21 could be manufactured with excellent moldability.

Further, various measurements and evaluations of these bonded magnets were performed in the same manner as in Example 1. Table 4 shows the results.

[0177]

[Table 4]

As is clear from Table 4, the sample No.
15-No. The bonded magnets according to _No. 21 (the present invention) all have magnetic properties (intrinsic coercive force H _cJ , maximum magnetic energy product (BH) _max ), heat resistance (thermal stability), corrosion resistance, molded appearance and mechanical strength. Are better.

Example 3 Six kinds of kneaded materials (samples No. 22 to No. 27) were prepared as follows using the magnet powder (average particle size 167.8 μm) obtained in Example 1.
Was manufactured.

The magnet powder and nylon 6 (softening point: 215
° C), nylon 12 (softening point 160 ° C), and tocopherol (an antioxidant) were charged into a kneading apparatus. In addition, a continuous twin screw extruder was used as a kneading device.

Thereafter, the materials were kneaded in an argon gas atmosphere. The material temperature during kneading was 210 ° C. At this time, as shown in Table 7, the kneading energy E per liter of the material was varied in a range of 0.07 to 3.5 kWh / L, and the magnet powder in the material, nylon 6, and nylon 12 were mixed. By varying the compounding ratio of the six kinds of kneaded materials (samples No. 22 to No. 2)
7) was manufactured. The compounding ratio of the antioxidant in the material was 4.0 vol%.

Using the magnet powder having an average particle diameter D ₀ of 117.3 μm obtained in Example 2, six kinds of kneaded materials (samples No. 28 to No. 33) were produced as follows. did.

Magnetic powder, nylon 6, nylon 1
2. A material composed of tocopherol (an antioxidant) was charged into a kneading apparatus. In addition, a continuous biaxial roll with grooves was used as a kneading device.

Thereafter, the materials were kneaded in an argon gas atmosphere. The material temperature during kneading was 210 ° C. At this time, as shown in Table 7, the kneading energy E per liter of the material was varied in a range of 0.07 to 3.5 kWh / L, and the magnet powder in the material, nylon 6, and nylon 12 were mixed. By changing the compounding ratio of the various types, six kinds of kneaded materials (samples No. 28 to No. 3)
3) was manufactured. The compounding ratio of the antioxidant in the material was 4.0 vol%. Table 5 summarizes the production conditions for these kneaded materials.

Further, a part of each kneaded material thus obtained was taken out, and the average particle diameter (D ₁ ) of the magnet powder in the kneaded material was measured as follows.

To a part of the kneaded product, a sufficient amount of chloral hydrate was added to dissolve the binder and the antioxidant. Thereafter, the solution was filtered to separate the magnet powder. After sufficiently washing and drying this magnet powder, it was classified using a sieve, and the weight average particle size was measured. Note that these operations were performed in an argon gas atmosphere.
For each sample, indicating the average particle diameter D ₁ of the kneaded in Table 5.

[0187]

[Table 5]

Then, using these kneaded materials, 200 columnar bonded magnets were manufactured as follows.

First, the kneaded material obtained as described above was pulverized into a granular material having an average particle size of about 0.5 mm. Next, the granulated material is weighed, filled into a mold of a press device, and compression-molded (without a magnetic field) at a mold temperature of 210 ° C. and a pressure of 50 kg / cm ² , and has a columnar shape of 10 mm in diameter × 7 mm in height. Was obtained.

In the same manner, for sample no. 22 ~
No. Using a kneaded material of 33, an outer diameter of 30 mm and an inner diameter of 28
200 cylindrical (ring-shaped) bonded magnets each having a size of 5 mm × 5 mm in height were manufactured. The sample No.
22-No. Each of the bonded magnets No. 33 was able to be manufactured with excellent moldability.

Various measurements and evaluations were performed on the bonded magnet thus obtained in the same manner as in Example 1.
Table 6 shows the results.

[0192]

[Table 6]

As is clear from Table 6, the sample No.
22-No. All of the bonded magnets according to the present invention 33 (invention) have _improved magnetic properties (specific coercive force H _cJ , maximum magnetic energy product (BH) _max ), heat resistance (thermal stability), corrosion resistance, molded appearance and mechanical strength. Are better.

A bonded magnet of the present invention was manufactured and subjected to various measurements and evaluations in the same manner as in Example 3 except that the bonded magnet was manufactured by extrusion. As a result, the same results as described above were obtained.

A bonded magnet of the present invention was manufactured and subjected to various measurements and evaluations in the same manner as in Example 3 except that the bonded magnet was manufactured by injection molding. The same results as described above were obtained.

[0196]

As described above, according to the present invention, the following effects can be obtained.

The kneading of the magnet powder is performed while the magnet powder is pulverized such that the average particle diameter of the magnet powder after kneading is smaller than the average particle diameter of the magnet powder in the material before kneading. It is possible to effectively prevent and suppress the oxidative deterioration of the powder. For this reason, the bonded magnet manufactured using the kneaded material obtained in this way has higher magnetic characteristics than the bonded magnet manufactured using the finely ground magnet powder in advance.

Further, by crushing the magnet powder while kneading the material, the adhesion between the magnet powder and the binder is improved, and the surface of the magnet powder is coated with the binder.

Therefore, excellent moldability can be obtained even when the amount of binder in the kneaded material is relatively small.

The obtained bonded magnet has corrosion resistance,
A bonded magnet with excellent heat resistance, mechanical strength, etc.

By adjusting conditions such as kneading energy, kneading temperature, and content of the magnet powder, the ratio of the average particle size of the magnet powder before and after kneading the material can be controlled. In addition, by appropriately adjusting the ratio of the average particle size of the magnet powder before and after kneading the material, the moldability into a bonded magnet, and the corrosion resistance, heat resistance, mechanical hardness, and the like of the obtained bonded magnet are further improved. can do.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of a composite structure (nanocomposite structure) in a magnet powder of the present invention.

FIG. 2 is a diagram schematically illustrating an example of a composite structure (nanocomposite structure) in the magnet powder of the present invention.

FIG. 3 is a diagram schematically showing an example of a composite structure (nanocomposite structure) in the magnet powder of the present invention.

FIG. 4 is an apparatus for manufacturing a magnet material (a quenched ribbon manufacturing apparatus).
It is a perspective view which shows the example of a structure of.

5 is a cross-sectional side view showing a state near a collision site of a molten metal with a cooling roll in the apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quenched ribbon manufacturing apparatus 2 Cylindrical body 3 Nozzle 4 Coil 5 Cooling roll 51 Base 52 Surface layer 53 Peripheral surface 6 Molten 7 Paddle 71 Solidification interface 8 Quenched ribbon 81 Roll surface 9A Arrow 9B Arrow 10 Soft magnetic phase 11 Hard magnetic phase

Continued on the front page F term (reference) 4K018 AA11 AA27 BA18 BB04 BB06 BC13 BD01 CA09 CA30 CA32 GA04 KA46 5E040 AA04 AC05 BB04 BB05 BD00 CA01 HB00 HB05 HB07 HB19 NN04 NN06 NN12 NN14 NN15 NN17 5E062 CC02 CD02 CE02

Claims (22)

[Claims] 1. A method for producing a bonded magnet, comprising: a step of kneading a material containing a magnet powder and a binder to obtain a kneaded material; and a step of molding the kneaded material to obtain a molded body. The kneading is performed while pulverizing the magnet powder so that the average particle diameter of the magnet powder after the kneading is smaller than the average particle diameter of the magnet powder before the kneading. Manufacturing method of magnet. 2. A bond comprising: a step of producing a magnet powder; a step of kneading a material containing the magnet powder and a binder to obtain a kneaded product; and a step of forming the kneaded product to obtain a molded body. A method for manufacturing a magnet, wherein the magnet powder is manufactured so that the average particle size is larger than the final average particle size, and the final average particle size is obtained by the kneading. Manufacturing method of a bonded magnet. 3. When the average particle size of the magnet powder before kneading is D ₀ [μm] and the average particle size of the magnet powder after kneading is D ₁ [μm], the following formula (I) is used. The method for producing a bonded magnet according to claim 1, wherein the method satisfies the following. 0.1 ≦ D ₁ / D ₀ ≦ 0.9 (I) 4. The method according to claim 1, wherein the material contains an antioxidant. 5. The method for producing a bonded magnet according to claim 1, wherein the average particle size of the magnet powder before the kneading is 10 to 1200 μm. 6. The method according to claim 1, wherein the average particle size of the magnet powder after the completion of the kneading is 1 to 500 μm. 7. The method according to claim 7, wherein the kneading is performed at a rate of 0.1 to 1 L of the material.
The method for producing a bonded magnet according to any one of claims 1 to 6, wherein the method is performed by applying a kneading energy of 07 to 3.5 kWh. 8. The method according to claim 1, wherein the content of the magnet powder in the material is 50 to 95 vol%. 9. The method according to claim 1, wherein the kneading is performed in an inert gas atmosphere. 10. The method for producing a bonded magnet according to claim 1, wherein the kneading is performed using a continuous twin-screw extruder or a continuous twin-screw roll. 11. The method according to claim 1, wherein the molding is performed by any one of compression molding, extrusion molding, and injection molding. 12. The method according to claim 1, wherein the magnet powder contains a rare earth element. 13. The magnet powder is an R-TM-B alloy (where R is at least one rare earth element, and TM is F
The method for producing a bonded magnet according to any one of claims 1 to 12, comprising a transition metal mainly composed of e. 14. The method for producing a bonded magnet according to claim 1, wherein the magnet powder has a composite structure having a hard magnetic phase and a soft magnetic phase. 15. The method according to claim 14, wherein the hard magnetic phase and the soft magnetic phase each have an average crystal grain size of 1 to 100 nm. 16. The method according to claim 1, wherein the binder includes a thermoplastic resin or a thermosetting resin. 17. The method according to claim 1, wherein the kneading is performed at a temperature equal to or higher than a softening point of the binder. 18. A bonded magnet manufactured by the manufacturing method according to claim 1. Description: 19. The bonded magnet according to claim 18, having a density of 4.0 to 8.0 Mg / m ³ . 20. An intrinsic coercive force H _cJ at room temperature of ₄₀₀ to 1
20. The bonded magnet according to claim 18 or 19, which is 500 kA / m. 21. The bonded magnet according to claim 18, wherein a maximum magnetic energy product (BH) _max is 50 kJ / m ³ or more. 22. The bonded magnet according to claim 18, wherein the absolute value of the irreversible demagnetization rate (initial demagnetization rate) is 8% or less.