JPH06204067A - Manufacture of bonded magnet - Google Patents

Abstract

PURPOSE:To provide the manufacture of a bonded magnet, which can easily and economically manufacture the bonded magnet having excellent magnetic properties without marring the mechanical strength. CONSTITUTION:The manufacture of a bonded magnet has a liquid addition process and a molding process. In the liquid addition process, the material powder consisting of mixture of magnetic powder and thermosetting resin is heated, and then liquid-form matter is added. In the molding process, a molded item is gotten by molding mixed powder where liquid substance is added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded magnet manufacturing method, and more particularly to a compression molded bond magnet manufacturing method.

[0002]

2. Description of the Related Art Permanent magnets are used in a wide range of fields from various electrical products to small precision equipment and actuators, and are one of the important electrical and electronic materials. Due to the recent demand for miniaturization and high efficiency of equipment, high-performance permanent magnets are required. In response to these demands, the demand for permanent magnets with high characteristics has grown rapidly over the last few years.
Permanent magnets are roughly classified into sintered magnets and bonded magnets. Bonded magnets have the advantage that sintered magnets such as those listed below cannot be obtained. Recently, the demand for various actuators has rapidly increased. ing. The advantages are as follows. (1) A thin shape can be easily obtained. (2) Less likely to be chipped as compared to a sintered magnet. (3) Excellent mass productivity.

The bonded magnets having such advantages can be roughly classified into molding methods, compression molding methods, injection molding methods, and extrusion molding methods. Among them, the compression molding method has a larger filling amount of the magnet powder in the molded body as compared with the other molding methods, so that a bonded magnet having high magnetic characteristics can be obtained. Conventionally, a method of manufacturing a bonded magnet by compression molding uses ferrite-based, SmCo-based, and NdFeB-based magnet powders as permanent magnet powders, mixes a thermosetting resin as a binder with the permanent magnet powders, and then mixes the mixed powders. It was a method of compression molding immediately after filling the mold with a mold. If compression molding is performed in a magnetic field, a bonded magnet having anisotropy can be manufactured.

[0004]

However, in the above-mentioned method for producing a bonded magnet by compression molding, the filling rate of the magnetic powder in the molded body cannot be increased sufficiently, and in particular, an anisotropic magnet for applying a magnetic field during molding is used. In this case, since the magnetic field orientation of the powder was poor, only compression-molded bonded magnets with low magnet characteristic values could be obtained.

Further, in order to solve the above-mentioned drawbacks, a method of adding a solid lubricant such as stearic acid to the mixed powder has been proposed, but generally, the mechanical strength of the compression molded magnet is remarkably lowered. Therefore, the method of adding a solid lubricant such as stearic acid was not a preferable method.

[0006] Therefore, a technical object of the present invention is to provide a method of manufacturing a bond magnet which can easily and inexpensively manufacture a bond magnet having excellent magnet characteristics without impairing mechanical strength.

[0007]

In order to obtain a compression-molded bonded magnet having excellent magnet characteristics, the inventors of the present invention heat a raw material powder, then add a liquid substance at room temperature and then mold it. As a result, they have found that the magnet characteristics of the bonded magnet are improved, and the present invention has been completed.

According to the present invention, in a method for producing a bonded magnet, a liquid adding step of adding a liquid substance after heating a raw material powder consisting of a mixture of magnetic powder and a thermosetting resin, and a step of adding the liquid substance. And a molding step of molding the added mixed powder to obtain a molded body. Here, in the present invention, rare earth magnet powder such as SmCo-based magnet powder and NdFeB magnet powder can be used as the magnetic powder.

In the present invention, the liquid substance added to the raw material powder is at least one of hydrocarbons, alcohols, esters, ethers, halides and ketones, and the raw material powder is heated. By doing so, the magnetic properties are remarkably improved. This is done by heating and adding a liquid substance between the magnetic powder and the magnetic powder,
This is because the frictional resistance between the magnetic powder and the thermosetting resin or between the thermosetting resin and the thermosetting resin decreases.

Further, when comparing the liquid substance used in the present invention with a solid lubricant such as stearic acid, since the liquid substance is a liquid, it does not remain in the molded body after curing, and it is Has the advantage that it has no adverse effect.

In the present invention, the amount of the liquid substance added to the raw material powder is arbitrary, but if it is too much, it is economically disadvantageous, and preferably 0 to the raw material powder.
It is 100% by weight (excluding 0).

[0012]

EXAMPLES The present invention will be described in more detail with reference to examples.

Example 1 A magnetic powder having a particle size of 25
SmCo-based alloy powder of 0 μm or less was used. Further, as the thermosetting resin, a powdery epoxy resin having a particle size of 100 μm or less at room temperature was used. The magnetic powder and the epoxy resin were mixed at a weight ratio of 97: 3. In order to make the mixing as uniform as possible, first dissolve the epoxy resin in acetone to form an acetone solution, add this magnetic powder to the solution, stir thoroughly, and dry at room temperature, then mix this mixed powder with 250 μm. It was crushed as follows. Then, this crushed powder was filled in a mold. Mold size is 1.2cm × 1.2
cm × L. The filling amount was 10.0 g. Next, after heating the powder to 100 ° C. in the mold, acetone of 0, 25, 50, 100, 150, 200 wt% was added to the powder. After that, about 1.6 MA / m (20 kO
Molding was carried out in the magnetic field of e) at a pressure of 5.0 ton / cm ² .
The molded bodies were held at 150 ° C. for 1 hour to cure the epoxy resin.

The relationship between the magnetic properties of the bonded magnet and the amount of acetone added at that time is shown in FIG. The comparative example is under the condition that acetone is not added.

From FIG. 1, it was found that the magnetic characteristics were improved by adding acetone to the raw material powder.
However, it was also found that the magnet characteristics were saturated at 15.7 MGOe (125.0 kJ / m ³ ) with 100% by weight of the raw material powder.

Next, the bending strength of the bonded magnet obtained in Example 1 was investigated. The relationship between the bending strength of these bonded magnets and the amount of acetone added is shown in Table 1 below.

[0017]

[Table 1]

As shown in Table 1, it was found that the bending strength was weakened when the amount of acetone added (% by weight) was 100% or more, but was less than that, the bending strength was sufficient. .

(Example 2) Using the same magnetic powder and epoxy resin as in Example 1, the same mixed powder as in Example 1 was prepared and crushed to obtain a sample powder. Next, 10.0 g of this sample powder is heated to 30 ° C, 60 ° C, 100 ° C,
0 (no addition), 25, 50, 100, 15 for each
After adding 0,200% by weight of isopropanol, 5.0 ton / cm in a magnetic field of about 1.6 MA / m (20 kOe).
Molded at a pressure of ² . The molded bodies were held at 150 ° C. for 1 hour to cure the epoxy resin to obtain bonded magnets. The relationship between the magnetic properties of the obtained bonded magnet and the amount of isopropanol added is shown in FIG.

From FIG. 2, it is recognized that the magnetic characteristics are improved by heating the mixed powder and adding isopropanol.

(Example 3) Using the same magnetic powder and epoxy resin as in Example 1, the same mixed powder as in Example 1 was prepared and crushed to obtain a sample powder. Next, 10.0 g of this sample powder was heated to 100 ° C., and the following 10 kinds of liquids were added to each 100% by weight of the powder to perform compression molding. The types of liquid are silicone oil, paraffin oil, hexane, methanol, methyl acetate, ethyl ether, carbon tetrachloride, chloroform (hexane):
(Methanol) = 1: 1 (hexane) :( acetone) =
It was a 1: 1 mixed solution. The compression molding condition is about 1.
It was 5.0 tons / cm ² in a magnetic field of 6 MA / m (20 kOe). These molded bodies were held at 150 ° C. for 1 hour to cure the epoxy resin to obtain bonded magnets. The bending strength and magnet characteristics of these bonded magnets are shown in Table 2 below.

[0022]

[Table 2]

From Table 2 above, by adding at least one of hydrocarbons, alcohols, esters, ethers, ketones and halides to the powder and compression molding, the magnetic properties can be remarkably improved. found. still,
Although the above-mentioned Table 2 shows combinations of up to two kinds of liquids, it can be easily inferred that similar effects can be obtained even if three kinds or more.

(Example 4) Neodymium, iron, boron (Nd-
2 parts by weight of an epoxy resin was added to 98 parts by weight of (Fe-B) based magnetic powder (MO-1 manufactured by GM), and they were sufficiently mixed and dispersed. The resulting mixture was compression molded under the conditions shown in Table 3 below at a pressure of 6 t / cm ² using a mold having an outer diameter of 20 mm × an inner diameter of 17 mm × L. The molded product was heat-cured at 150 ° C. for 1 hour. As Comparative Example (b), the same treatment as in Example 4 except that the heat treatment was not performed at the time of molding, and Comparative Example (c) in which the heat treatment and the liquid addition were not performed were also performed as in Example 4. With respect to the same treatment, various characteristics were measured in the same manner as in Example 4. The results are shown in Table 3 below.
It is understood that the method according to Example 4 of the present invention has the highest molded product density and is excellent in magnetic characteristics.

[0025]

[Table 3]

[0026]

As described above, according to the present invention, a bonded magnet having high magnet characteristics can be provided easily and inexpensively without impairing the mechanical strength, which is extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a magnet characteristic of a molded body obtained by heating a raw material powder of a bonded magnet according to Example 1 of the present invention to 100 ° C. and adding acetone, and an addition amount of acetone to be added. .

FIG. 2 is a graph showing the magnet characteristics of a molded body formed by heating raw material powder of a bonded magnet according to Example 2 of the present invention to 30 ° C., 60 ° C., and 100 ° C., and adding isopropyl alcohol to the molded body. It is a figure which shows the relationship with quantity.

Claims (4)

[Claims] 1. A method for producing a bonded magnet, comprising a step of adding a liquid substance after heating a raw material powder made of a mixture of magnetic powder and a thermosetting resin, and adding the liquid substance. And a molding step of molding a mixed powder to obtain a molded body. 2. The method for manufacturing a bonded magnet according to claim 1, wherein the liquid substance is at least one of hydrocarbons, alcohols, esters, ethers, halides and ketones. A method for manufacturing a bonded magnet. 3. The bond magnet manufacturing method according to claim 1, wherein the amount of the liquid substance is 0 to 100% by weight (not including 0) with respect to the weight of the raw material powder. Magnet manufacturing method. 4. The method for producing a bonded magnet according to claim 1, wherein the heating temperature of the raw material powder is in the range of 30 to 150 ° C.