JPH0212801A - Compound for bonding magnet and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the title compound wherein fluidity at the time of formation is excellent, and multipole anisotropy or radial anisotropy is easy to be imparted in a comparatively weak magnetic field by using material is R-TM-B base alloy powder, and is composed of surface-treated magnetic powder with a specified grain diameter and resin, and whose melt.index value is in a specified range. CONSTITUTION:The title compound is a material which is R-TM-B base alloy powder and is composed of surface-treated magnetic powder with an average grain diameter of 1-1000mum and resin, and whose melt.index value is 10-300g/10min. Where R is one or more kinds of rare earth elements containing Y. TM is Fe or one wherein a part of Fe is replaced by Co, and B is boron. For example, the above alloy powder composition is as follows; the rare earth elements R are 11-18at%, boron B is 4-11at%, transition metal TM is composed of Co less than or equal to 30at%, and the residual part is practically Fe. The surface treatment of magnetic powder is desirable to be a compound treatment using titanate system coupling agent after a processing using silane system coupling agent. Because of excellency in forming properties and the like, polyamide resin, in particular, nylon 6 and nylon 12 are preferable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a compound used for a bonded magnet,
Melt index (M) without changing the resin
I) A compound for bonded magnets whose fluidity is significantly improved by increasing the value.

[Prior Art] Compounds for bonded magnets, which are mixtures of surface-treated magnetic powder and resin, are well known (see, for example, Japanese Patent Laid-Open No. 86803/1983). The compound is a mixture obtained by mixing magnetic powder and resin and passing through 9 classifications to form pellets, and is made into a bonded magnet by a molding method such as compression molding or injection molding.

The most common type of magnetic powder is hard ferrite, but rare earth cobalt magnets have also been used in many applications that require high magnetic properties. New materials such as rare earths, transition metals, and
It is also known that boron-based (hereinafter abbreviated as R-TM-B-based) permanent magnet alloy powder is substituted (for example, JP-A-59
-211549.59-219904.60-2215
(See Publication No. 49).

Furthermore, in general, as the molecular weight of a resin decreases, its melt viscosity decreases and processability improves. However, mechanical properties and solvent resistance deteriorate. The molecular weight is expressed as the melt index (hereinafter abbreviated as MI value), which indicates the state of melt flow, and this is the melt index (hereinafter abbreviated as MI value) that indicates the state of melt flow. IQIIll
It is expressed as the number of grams extruded in 10 minutes when extruded from an orifice with a length of 8 mm and 0 mm under a load of 2160 g (see ASTM D-1238). It is known that the smaller the MI value, the larger the molecular weight, and the higher the mechanical strength, but the worse the fluidity during molding. It has also been known for a long time that it is necessary to select an MI value within an optimal range for a resin for compounding a bonded magnet (see, for example, Japanese Patent Laid-Open No. 54-9794).

[Problems to be Solved by the Invention] However, the above-mentioned bonded magnets do not necessarily have sufficient magnetic properties, and in particular, the cylindrical magnet's circumferential surface has radial or multipolar anisotropy, which is called ring anisotropy. (For example, Japanese Patent Laid-Open No. 57-199205), the magnetizing magnetic field strength was low and insufficient characteristics could be obtained.

Therefore, the purpose of the present invention is to provide a compound for bonded magnets that has good fluidity during molding and has mechanical strength comparable to conventional ones. The present invention provides a bonded magnet compound that is easily imparted with anisotropy.

[Means for Solving the Problems] The first invention of the present invention provides an R-TM-B-M alloy powder (where R is one or more rare earth elements including Y, TM
is Fe or a part of Fe.

2M is an additive element added as necessary to improve coercive force, and B is an additive element added as necessary to improve coercive force.
Al, Nb, Zr, Hf, Mo, P.

(one type or a combination of two or more types of C), which is made of surface-treated magnetic powder with an average particle size of 1 to 1000 μ weight and a resin,
Melt index value (MI value) is 10-300g/
The present invention provides a compound for bonded magnets, which is characterized by having a low content of 10%.

In the present invention, the MI value of the compound is log/10
If it is less than 300 g/10 min, the moldability will be poor and it will be difficult to obtain a complex shaped object such as a ring anisotropic magnet, and if it exceeds 300 g/10 min, the strength of the molded product will be significantly reduced.

The magnetic powder in the present invention may be produced by any conventionally known method, that is, a cast ingot may be pulverized, or a melted alloy may be pulverized into flakes by ultra-quenching, and The magnetic powder obtained in this way is molded into a molded body (no magnetic field application required), and after densification is achieved by hot pressing, plastic flow is caused by warm swaging, resulting in magnetic anisotropy. After applying, re-pulverized magnetic powder may be obtained.

The reason why the average particle size of the magnetic powder of the present invention is limited to 1 to 1000 μm is because if the average particle size is less than 1 μm, it is easy to catch fire and difficult to handle in the air, and if it exceeds 1000 μm, the thickness is 1 μm. This is because it is applicable to thin articles with a thickness of ~2 yen and is unsuitable for injection molding.

The composition of the R-TM-B-M alloy powder according to the present invention is that the rare earth element R is 11-18 at%, and the boron B is 4-11 at%. at%
, the additive element M is 3 at% or less, and the transition metal TM has Go of 3 at%.
It is preferable that the balance is substantially Fe at 0 at% or less. The reasons for limiting the composition of the magnetic powder in the present invention are as follows.

In other words, if the rare earth R is less than l lat%, there is sufficient x
If Hc is not obtained and it exceeds 18 at%, 4πIr decreases. When boron B is 4 at% undropped, the main phase R
, Fei, phase formation is not sufficient, 4πIr and xHc
Both are low. If it exceeds 11 at%, 4πIr decreases due to the appearance of a phase with unfavorable magnetic properties.

The amount of Co has a remarkable effect on raising the Curie temperature and improving thermal stability, but if it exceeds 30 at%, the anisotropy number of the main phase decreases and high xHc cannot be obtained.

Ga, Si, Al, Nb, Zr, Hf, Mo.

P and C are effective in improving the coercive force wHc, and the effect of Ga is particularly remarkable. However, if it exceeds 3 at%, 4πI
This is not preferable because it causes a decrease in r. Therefore, it is preferable that the total amount does not exceed 3 at% even when a combination is added.

In the present invention, the magnetic powder may be surface-treated with any coating agent that suppresses oxidation, such as a silane-based, titanate-based, or zircoaluminate-based coupling agent.

In particular, it is most preferable to perform a treatment with a silane coupling agent and then a composite treatment with a titanate coupling agent.

In the present invention, the resin may be any known resin such as polyamide, polyferene sulfide, polyether sulfone, etc., but polyamide resins, particularly nylon 6 and nylon 12, are preferred from the viewpoint of good moldability.

In the present invention, further improvement in moldability can be expected by adding stearamide.

The second invention of the present invention is an R-TM-B-M alloy powder (where R is one or more rare earth elements including Y, TM
is Fe or a part of Fe.

B is boron 1M is an additive element added as necessary, and Ga, Si, AM, and Nb.

One type or a combination of two or more of Zr, Hf, Mo, P, and C) is pulverized to an average particle size of 1 to 1000 μm, then subjected to surface treatment and kneaded with resin under the action of shear force to form a melt. The present invention provides a method for producing a compound for bonded magnets that provides an index value of 10 to 300 g/10 min. In particular, it is optimal to apply shear force by twin-screw extrusion.

Conventionally, it has been considered extremely difficult to balance mechanical strength and fluidity during molding. As a means to solve this problem, the present inventors have attempted to improve mechanical strength and fluidity during molding by controlling the MI value within the optimum range by kneading the same type of resin under the action of shear force. It has been discovered that a compound for bonded magnets that satisfies both requirements can be obtained. Therefore, according to the present invention, sufficient orientation can be obtained even in a weak magnetic field, especially when imparting multipolar anisotropy.

Any conventionally known method can be used to apply the shearing force, but twin-screw extrusion is particularly optimal.

[Example] (Example 1) An alloy containing 15% Nd, 77% Fe, 87% Fe, and 1% Ga in atomic percent was created by arc melting, and the peripheral speed was 30% in an Ar atmosphere.
Flake-like thin pieces were prepared by a single roll method of m/see. This flake was coarsely ground to 32 meshes or less, and a molded body having a density of 5.8 g/Co+' was produced by molding at a molding pressure of 6 tons/clI2 in the absence of a magnetic field.

Next, hot press at 2 tons/cm” to a density of 7.30 g/cm.
A compacted body of cm' was obtained. Magnetic anisotropy was then imparted by upsetting. The ratio of the height ho before upsetting to the height h after upsetting, ho/h, was chosen to be 3.8. After swaging, it was heated to 750 g/10 minutes in AQ, held for 60 minutes, and then cooled in water. The powder was then coarsely ground to obtain magnetic powder.

Next, 0.5 weight of a silane coupling agent was added to 100 weight of the obtained magnetic powder, and the mixture was mixed and stirred for 10 minutes using a high-speed mixer. After drying at 80° C. for 1 hour, 1.0 weight 2 of isopropyl tris[2(2aminoethylamino)ethoxy]titanate was added and mixed and stirred for 10 minutes using a high-speed mixer. Furthermore, the MI value is 50
A mixture was prepared by adding 8.0 weight fi 1% of nylon 12 powder of g/10 minutes and mixing with a high speed mixer. This mixture was twin-screw kneaded and extruded to give an MI value of 21.5g/10
A pellet-shaped compound for bonded magnets was obtained.

Next, injection molding was performed in an injection molding machine equipped with a mold capable of imparting 10 poles of polar anisotropy (orienting magnetic field strength of 3 KOe). The injection time is 6 seconds. The dimensions of the obtained cylindrical molded body are outer diameter φ8 x inner diameter φ2 x height 15 (mm).

When the obtained compact was anisotropically magnetized with 10 poles at a magnetic field strength of 15 KOe, the surface magnetic flux density was 2800 G.

This value is 21 for the uniaxial kneading extrusion comparative example 1).
700G is also higher than 00G.

(Comparative Example 1) A 10-pole anisotropic bonded magnet was obtained in exactly the same manner as in Example 1 except that the mixed wire extrusion method was uniaxial kneading extrusion.

(Example 2) In the same manner as in Example 1, the shear force was changed by changing the shape of the screw of the twin-screw kneading extruder, and the MI value was changed.
H) wax, crushing strength 2 surface black flux density of the molded body was measured. Here, the crushing strength of the compact was measured by the strength at which the obtained ring magnet broke when it was crushed by setting it in an Amsura testing machine. As shown in Table 1, the MI value is 10~
It can be seen that (B)I)IIIax and surface magnetic flux density are good in the range of 300 g/lo min, and the crushing strength of the molded body is also sufficient.

Table 1 (Example 3) Other conditions were the same as in Example 1, and bonded magnets were prepared using alloys with various compositions and their magnetic properties were measured. The results are shown in Table 2.

It can be seen that according to the present invention, a bonded magnet having excellent magnetic properties can be obtained.

Table 2 (1) Table 2 (Example 4) The fist shows comparative examples Bonded magnets were obtained in the same manner as in Example 1 except that the type of resin was changed. The results are shown in Table 3. It can be seen that both good surface magnetic flux density and good crushing strength can be obtained according to the present invention regardless of the type of resin.

[Effects of the Invention] According to the compound according to the present invention, a compound having good fluidity during molding and having a complicated shape can be easily obtained, and a bonded magnet with excellent mechanical strength and high surface magnetic flux density can be obtained. , it becomes easier to increase the number of units such as stepping motors and downsize them.

Claims (6)

[Claims] (1) R-TM-B alloy powder (where R is one or more rare earth elements including Y, TM is Fe or a part of Fe replaced with Co, and B is boron). Made of surface-treated magnetic powder and resin with an average particle size of 1 to 1000 μm, and has a melt index value of 10 to 300 g/10
A compound for bonded magnets, which is characterized by the fact that: (2) The composition of the R-TM-B alloy powder is such that the rare earth element R is 11 to 18 at%, boron B is 4 to 11 at%, and the transition metal TM is Co, which is 30 at% or less, and the balance is substantially Fe. The compound for bonded magnets according to claim 1, characterized in that: (3) R-TM-B-M alloy powder (where R is one or more rare earth elements including Y, TM is Fe or F
Part of e is replaced with Co, B is boron, M is Ga,
Si, Al, Nb, Zr, Hf, Mo, P, C (one type or a combination of two or more types), it is made of surface-treated magnetic powder with an average particle size of 1 to 1000 μm and a resin, and has a melt index value A compound for bonded magnets, characterized in that: 10 to 300 g/10 minutes. (4) The composition of the R-TM-B-M alloy powder is 11 to 18 at% of rare earth element R, 4 to 11 at% of boron B, 3 at% or less of additive element M, and 30 at% of Co of transition metal TM.
The compound for bonded magnets according to claim 3, wherein the balance is substantially Fe. (5) R-TM-B-M alloy powder (where R is one or more rare earth elements including Y, TM is Fe or F
A part of e is replaced with Co, B is boron, and M is an additive element added as necessary, including Ga, Si, Al, and N.
b, Zr, Hf, Mo, P, and C) to an average particle size of 1 to 1000 μm, and then subjected to surface treatment and kneaded with resin under the action of shear force. Melt index value 10-300g/10
A method for producing a compound for bonded magnets that yields the desired results. (6) The method for producing a bonded magnet compound according to (5), wherein the shearing force is applied by twin-screw extrusion.