JPH02292802A - Manufacture of bonded magnet - Google Patents

Abstract

PURPOSE:To form granulated powder having improved mechanical strength and fluidity, and to make it possible to manufacture a bonded magnet having excellent magnetic characteristics and the small irregularity therein using the above-mentioned granulated powder by a method wherein thermosetting resin and unsaturated fatty acid are added to a permanent magnet powder, they are kneaded and dried up, and after the granulated powder has been molded, it is cure-treated. CONSTITUTION:Thermosetting resin and unsaturated fatty acid are added to a permanent magnet powder, they are kneaded, dried up and granulated. After the granulated powder, which is formed by three-dimensionally polymerized unsaturated fatty acid and the thermosetting resin, has been molded, a cure-treatment is conducted. For example, the quenched thin band of Nd-Fe-B-Co permanent magnet material is pulverized, 6g of epoxy resin as thermosetting resin and 1g of oleic acid as unsaturated fatty acid are added to powder of 200g which has passed through 170-mesh screen (88mum mesh opening), they are kneaded in a mortar, dried up by a drying machine at 50 deg.C for 48 hours, the powder is granulated using a granulating machine, and the granulated powder having grain size of 500mum. Then, the granulated powder is molded, a cure-treatment is conducted at 120 deg.C for one hour, and a bonded magnet is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a bonded magnet in which permanent magnet powder is bonded using a resin binder, and more specifically, the present invention relates to a method for manufacturing a bonded magnet in which permanent magnet powder is bonded using a resin binder. This article relates to a method for manufacturing bonded magnets using unsaturated fatty acids. [Prior Art] Bonded magnets, which are made by compounding permanent magnet powder with a resin binder, are conventionally known. A thermoplastic resin or a thermosetting resin is used as the resin binder. It is manufactured by various molding methods such as compression, injection, extrusion, and rolling, among which compression molding is generally used because it can produce a high energy product.

Such pound magnets have advantages such as high magnetic properties, excellent mass productivity, easy dimensional accuracy, and a large degree of freedom in shape, and are rapidly being used in a variety of applications in recent years.

In terms of improving mechanical strength and fluidity, PVA and PV
Although it is desirable to use a solvent-soluble resin such as B as a binder, it is necessary to add a large amount of resin, which results in low molding density and poor magnetic properties. Therefore, usage conditions and applications are limited.

On the other hand, pound magnets that use a thermosetting resin such as epoxy resin as a binder have the characteristic that the maximum energy product can be increased because the amount of resin is small.

This type of bonded magnet is usually made by kneading and granulating permanent 6ff stone powder, thermosetting resin, and lubricant or surface treatment agent.
It is manufactured by molding the granulated powder and then curing the resin binder contained therein.

[Problems to be Solved by the Invention] When a thermosetting resin such as an epoxy resin is used, the strength of the granulated powder is low because it is in a liquid state.

For this reason, there is a problem in that the granulated powder is destroyed by a sliding operation or the like during filling into a mold.

Additionally, this type of granulated powder before heat curing is generally sticky;
Poor liquidity. For these reasons, there is a drawback that the amount of granulated powder filled into the mold is small and uniform filling is difficult, resulting in large variations in the product.

Although these drawbacks can be improved to some extent by adding a lubricant or a surface treatment agent as described above, the results are not necessarily fully satisfactory.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, to create a granulated powder with improved mechanical strength and fluidity, and by using the same, to produce a bonded magnet with excellent magnetic properties and less variation. The purpose is to provide a method for manufacturing.

[Means for Solving the Problems] The present invention, which can solve the above-mentioned technical problems, involves adding a thermosetting resin and an unsaturated fatty acid to permanent magnet powder, kneading it, drying it, and granulating it. , is a method for producing a bonded magnet in which a granulated powder in which an unsaturated fatty acid and a thermosetting resin are three-dimensionally polymerized is molded and then cured.

Here, examples of unsaturated fatty acids include oleic acid, linoleic acid, and linolenic acid, and the addition amount thereof is sufficient to be about 0.1 to 3% based on the permanent magnet powder.

[Function] The unsaturated fatty acids present together with the thermosetting resin in the granulated powder are oxidized when exposed to air. This reacts with the thermosetting resin to form a three-dimensional polymer. For this reason, the surface of the powder particles is covered with a semi-solidified layer, and the kneaded product of the permanent magnet powder, thermosetting resin, and unsaturated fatty acid locks to generate strength. At the same time, the tackiness of the surface of the granulated powder is reduced and the fluidity is improved. This makes it possible to uniformly fill the mold with granulated powder.

[Example 1 (Granulation)] A quenched ribbon of Nd-Fe-B-Go permanent magnet material was pulverized and 200 g of powder was passed through 170 mesh iJ1 (opening 88 μm), and epoxy was added as a thermosetting resin. resin 6
g and 1 g of oleic acid as an unsaturated fatty acid were added, kneaded in a mortar, and dried in a dryer at a temperature of 50° C. for 48 hours.

This powder was granulated using a granulator (sample LA of the present invention)
. The particle size of this granulated powder was 500 to 800 μm. For comparison, the same material as above was used and granulated without drying (comparative sample 1B) (Strength of granulated powder) The maximum breaking load of the granulated powder was measured using a Pelleft hardness needle. It was measured. The results of the measurements performed 10 times are as follows.

・Sample IA of the present invention...25-30g ・Comparative sample IB...Ig or less A large difference was observed between inventive sample 18 and comparative sample IB.

(Fluidity of granulated powder) The angle of repose was measured to examine the fluidity of granulated powder. - Inventive sample IA: 32 degrees - Comparative sample IB: Poor fluidity 11 Unable to determine (filling amount and variation) Sliding feed was carried out into a ring-shaped mold with an outer diameter of 18 mmφ/inner diameter of 16 mmφ. Table 1 shows the measurement results of the average filling amount and the variation σ7 of the five feeds.

Table 1 (Molding density) The above granulated powder was molded and cured at 120° C. for 1 hour, and then the density was measured.

The measurement results are as follows.

- Sample of the present invention I A-6. 10 g/cm3・Comparative test 141B...5. 7 9 g/cm3 [
Example 2] (Granulation) Sm2Co+, 125 μm of permanent magnet powder crushed and sieved
m or less powder), 4 g of epoxy resin as a thermosetting resin and 1 g of oleic acid as an unsaturated fatty acid.
g was added, kneaded in a mortar, and dried in a dryer at a temperature of 90° C. for 1 hour. This powder was granulated using a granulator (
Invention sample 2A) The particle size of this granulated powder is 500-84
It was 0 μm. For comparison, the same material as above was used and granulated without drying (Comparative Sample 2B) (Strength of Granulated Powder) The measurement method was the same as in Example 1 above. The measurement results of the maximum breaking strength are as follows.

Invention sample 2A...20-25g ・Comparative sample 2B...1g or less (Fluidity of granulated powder) The angle of repose was measured in the same manner as in Example 1.

- Inventive sample IA: 35 degrees - Comparative sample IB: Poor fluidity (unmeasurable (filling amount and variation)) Table 2 shows the results of cutting and feeding into the mold in the same manner as in Example 1.

Table 2 (Molding density) In the same manner as in Example 1, the above granulated powder was molded, and 12
After curing at 0° C. for 1 hour, the density was measured. The measurement results are as follows.

・Sample 2A of the present invention...6. 90 g/cm'・
Comparative sample 2B...6. 5 7 g/cta3 [
Effects of the Invention] As described above, the present invention is configured such that unsaturated fatty acids are added to permanent magnet powder together with a thermosetting resin, kneaded, and granulated after drying. The unsaturated fatty acids are oxidized in the air, which reacts with the thermosetting resin to form a three-dimensional polymer. As a result, the surface of each powder particle is covered with a semi-solidified layer, so the strength of the granulated powder is improved, and the adhesiveness of the surface is reduced, so fluidity is improved. As a result, the amount of granulated powder filled into the mold becomes large and uniform, improving the magnetic properties of the product and significantly reducing variations.

Patent applicant: Fuji Electrochemical Co., Ltd.

Claims (1)

[Claims] 1. A granulated powder in which a thermosetting resin and an unsaturated fatty acid are added to permanent magnetic powder, kneaded, dried, and then granulated to form a three-dimensional polymer of the unsaturated fatty acid and the thermosetting resin. 1. A method for manufacturing a bonded magnet, which comprises molding using a bonded magnet and then performing a curing treatment.