JPS63160314A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To prevent a molded material from being cracked and to enhance the corrosion resistance by a method wherein, after a molding assistant selected from zinc stearate, magnesium stearate and calcium stearate, and a thermosetting resin have been added to rare-earth magnetic powder and have been mixed, they are compressed and molded. CONSTITUTION:After rare-earth magnetic powder, a molding assistant in the form of a stearic-acid-related lubricant and furthermore a thermosetting resin have been mixed, they are fed into a compression mold and are molded by being pressurized at a pressurization force of e.g., about 3-10 tons/cm<2>. As for the rare-earth magnetic powder, the rare-earth-cobalt-related magnetic powder or the rare-earth-iron-related magnetic powder is usable. As for the molding assistant, the powdery lubricant to be selected from zinc stearate, magnesium stearate and calcium stearate is used; in this case, it is especially desirable that the volume to be added is in the range of 0.05-5 wt. %. By this method, a molded material is hard to crack during a compression molding process or at a knockout after the process; the yield rate of a permanent magnet is enhanced sharply; the corrosion resistance is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a permanent magnet used for manufacturing a plastic magnet by compression molding.

(Prior Art) Conventionally, plastic magnets manufactured by compression molding using thermosetting resins such as epoxy resins are manufactured by compression molding at a pressure of about 3 to 10 tons 7'cm2 in order to obtain high magnetic properties. It was being produced.

(Problem to be Solved by the Invention) Therefore, in plastic magnets manufactured by conventional compression molding, since the plastic magnets are pressure molded under high compression pressure as described above, the The problem was that the body was prone to cracks.

Furthermore, the amount of resin added to the magnet powder for plastic magnets manufactured by pressure molding is relatively small compared to, for example, the amount of resin added to plastic magnets manufactured by injection molding.
(for example, 1 to 5% by weight), the magnet powder is not completely covered with the resin, which leads to the formation of rust in a humid environment, and there is also the problem that corrosion resistance is not necessarily good.

(Object of the Invention) This invention has been made by focusing on the above-mentioned conventional problems, and when molding a plastic magnet by compression molding, the molded body is Resistant to cracking, r#
The object of the present invention is to provide a method for manufacturing a permanent magnet that makes it possible to manufacture a plastic magnet with improved edibility.

[Structure of the Invention] (Means for Solving the Problems) A method for manufacturing a permanent magnet according to the present invention includes adding a forming aid selected from zinc stearate, magnesium stearate, and calcium stearate to rare earth magnet powder. It is characterized in that a thermosetting resin is added thereto, mixed, and then compression molded.

Examples of rare earth magnet powder to which this invention is applied include rare earth-cobalt magnet powder and rare earth-iron magnet powder.The former rare earth-cobalt magnet powder includes RM5 magnet powder, such as Sm (Co, Fe, Cus bankai)
s system, R2M,, system, such as Sm2 (Co, F
e, Cu...) 17 series, and the latter rare earth-iron based magnet powder is "1-a-β-a (F
e (N i , Mn , Co) ) ctXβM
, R is one or more rare earth elements, X is B, C
.

N, St, Pc7) one or more, M is Ti, Zr.

Hf, V, Nb, Ta, Cr, Mo, W, Al.

One or more types of Zn, Ga, In, T-text, etc., more preferably 0.60≦α≦0.85゜O × β≦0.15
．． There are examples of 0≦γ≦0.01, but there is no particular limitation.

Further, as a forming aid added to the rare earth magnet powder, a powder lubricant selected from zinc stearate, magnesium stearate, and calcium stearate is used, and the amount added in this case is 0.05 to 5% by weight. It is particularly desirable to have a range of . The reason for this is that if the amount of powder lubricant added is too small, it will not be able to sufficiently prevent cracks from forming in the molded product during compression molding or knockout after molding. On the other hand, if the amount of the stearic acid-based powder lubricant added is too large, it will not be possible to obtain a good bond between the magnet powder and the resin, the strength and magnetic properties will decrease, and the thermosetting after compression molding will deteriorate. The amount eluted during the curing process of the plastic resin becomes too large, making it difficult to handle. Taking this into consideration, it is desirable that the amount of the molding aid added be in the range of 0.05 to 5% by weight. .

In addition, when an appropriate amount of the above-mentioned molding aid is added, the molding aid melts during the curing process of the thermosetting resin after compression molding, oozes out and adheres to the surface of the molded product, and forms a protective film. It has been found that the effect of improving corrosion resistance can also be obtained because of the formation of

Then, after mixing the above rare earth magnet powder, a molding aid which is a stearic acid-based lubricant, and further a thermosetting resin, the mixture is charged into a compression mold, and the mixture is heated, for example, from 3 to 10 tons/h.
A molded article having a desired shape is obtained by compression molding with a pressure of about cm2.

Next, if necessary, for example, 1
It is more desirable to perform a curing treatment by heating at about 00 to 170° C. to improve the magnetic properties and further improve the corrosion resistance due to the stearic acid-based lubricant being eluted and adhered to the surface.

Furthermore, after the compression molding, if necessary, a thermosetting resin curing agent may be applied to the surface of the molded body to further improve the corrosion resistance of the permanent magnet.

(Example 1) 3ONd-I pulverized to a particle size of 200 lm or less after ultra-quenching
Add 5.0% zinc stearate to B-Fe rare earth magnet powder
After adding 2.0% by weight of epoxy resin as shown in Table 1 and mixing with 2.0% by weight of epoxy resin, 7 to
By compression molding with a pressure of n/cm2, the diameter is 1.
1mm.

Ten cylindrical molded bodies each having a height of 10 mm were manufactured for each sample No. 31 to No. 7.

Next, the presence or absence of cracking in each molded body was examined, and the results are shown in Table 1.

Next, the molded body was heated at 150°C for 4 hours.

After curing in a vacuum of 10 Torr, a humidity test was performed at a temperature of 50'' C2 humidity 98% 9 hours M96 HrI), and the presence or absence of rust was visually inspected. Magnetic properties ((BH)
max) was investigated. These results are also shown in Table 1.

As is clear from the results shown in Table 1, in the case of sample No. 1 in which zinc stearate was not added, cracks were observed in all of the compression molded products (10 out of 10).

Furthermore, it was confirmed that even after the wet test, rust occurred on the entire surface, resulting in a significant decrease in magnetic properties.

In the case of sample No. 12, in which 0.01% by weight of zinc stearate was added, the number of cracks in the molded products was drastically reduced to 2 out of 10, and the occurrence of rust after the wet test was also very small. The decline in magnetic properties is also much smaller,
In the case of Test Nos. 3 to 7 in which 0.05% by weight or more of zinc stearate was added, no cracking of the molded bodies was observed, and no rusting was observed after the wet test.

It should be noted that if zinc stearate is added in excess of 5.0% by weight, there is no disadvantage in terms of preventing the occurrence of cracks and rust, but if too much is added, the strength and magnetic properties tend to decrease. During the curing process of thermosetting resins (epoxy resins), the amount of zinc stearate eluted increases, making it difficult to handle and potentially causing problems in production, so it is recommended that the amount be 5.0% by weight or less. I understand.

(Example 2) After solution-treating an ingot made of 25Sm-15Fe-4Cu-2Zr-Co at 1170°C for 4 hours,
After holding at 825°C for 5 hours, cooling to 400°C at a rate of 2°C/min, aging treatment was performed by holding at 400°C for 10 hours, and then in an inert atmosphere using a show crusher and a disk crusher to obtain particles with an average particle size of 30 g. crushed to.

Next, 2.0% by weight of epoxy resin was added and mixed to the above magnetic powders, one without zinc stearate and one with 0.5% by weight of zinc stearate, and then 7 tons on 7cm2 Ten cylindrical molded bodies having a diameter of IZmm and a height of 10 mm were manufactured for each sample No. 8.9 by compression molding with a pressure of .

Next, the presence or absence of cracking in each molded body was examined, and the results are shown in Table 2.

Next, the molded body was heated at 150°C for 4 hours.

After curing in a vacuum of 10 Torr, 9
A basic spray test for 6 hours was conducted and the presence or absence of rust generation was visually examined. Furthermore, for reference, the magnetic properties ((BH)max) before and after the salt spray test were investigated. These results are also shown in Table 2.

As is clear from the results shown in Table 2, in the case of sample No. 8 in which zinc stearate was not added, cracks were observed in all of the compression molded products (10 out of 10).

Furthermore, it was confirmed that even after the salt spray test, rust occurred over the entire surface, resulting in a significant decrease in magnetic properties.

To this, 0.5% by weight of zinc stearate.

In the case of the added sample No. 089, no cracking was observed in the molded body, no rust was observed after the salt spray test, and no deterioration of magnetic properties was observed.

[Effects of the Invention] As explained above, in the method for manufacturing a permanent magnet according to the present invention, a molding aid selected from zinc stearate, magnesium stearate, and calcium stearate is added to rare earth magnet powder, and at the same time, heat curing is performed. Since permanent magnets are manufactured by adding and mixing a magnetic resin and then compression molding, when manufacturing permanent magnets by compression molding, there is no problem with the molded body during compression molding or when knocking out after compression molding. Since cracks are less likely to occur, the manufacturing yield of permanent magnets can be greatly improved, and at the same time, it is possible to produce plastic magnets with extremely excellent corrosion resistance, which is an extremely excellent effect.

Claims (3)

[Claims] (1) Permanent magnet powder characterized by adding a molding aid selected from zinc stearate, magnesium stearate, and calcium stearate to rare earth magnet powder, and adding and mixing a thermosetting resin, followed by compression molding. How to manufacture magnets. (2) The method for producing a permanent magnet according to claim (1), characterized in that the amount of the forming aid added is in the range of 0.05 to 5% by weight. (3) The method for manufacturing a permanent magnet according to claim (1) or (2), characterized in that a curing treatment is performed after compression molding.