JPS63147302A - Composite material for permanent magnet and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a rare-earth plastic magnet whose magnetic characteristic is enhanced, whose mechanical strength is high and whose dimensional stability is excellent by using a composite material which is composed of a powdered magnetic intermetallic compound, a liquefied thermosetting resin material and a plasticizer, of their respective prescribed amounts, so that a load on a mold during the formation can be reduced and that the density of a molded product can be enhanced at the same time. CONSTITUTION:A composite material composed of the following three is used: a powdered magnetic intermetallic compound which is composed mainly of a rare-earth metal and a transition metal, at 50-95 vol. %; a liquefied thermosetting resin material; a plasticizer which is composed of 5-100 weight parts in relation to 100 weight parts of a solidified body of the liquefied thermosetting resin material, the latter two constituting the remaining volume percentage. After said composite material has been compressed and formed at the normal room temperature, it is hardened and solidified at the hardening temperature for said liquefied thermosetting resin material so as to obtain a formed material. As said powdered magnetic intermetallic compound, it is preferable to use a mixture of different groups of particle size ranging from 1 mum to 1 mm in diameter; as the liquefied thermosetting resin material, it is preferable to use a phenolic resin material, especially a resol-type phenolic resin material. In addition, as the plasticizer, a polyester plasticizer, a phthalate ester plasticizer, a phosphoric ester plasticizer or the like is suitable.

Description

[Detailed Description of the Invention] C. Industrial Application Field] The present invention relates to a permanent magnet material composition and a method for molding the same;
More specifically, it is made of an intermetallic compound magnetic powder mainly composed of rare earth metals and -a-transfer metals, and a liquid thermosetting resin containing a plasticizer as a binder, which has good moldability, magnetic properties, and mechanical strength. The present invention relates to a composition and a method for molding the same.

[Conventional technology and problems]

Alloy magnets whose main components are rare earth metals and transition metals (hereinafter referred to as rare earth magnets) have superior magnetic properties compared to conventional ferrite and alnico magnets.
In recent years, it has been used in a variety of fields, mainly in small motors. Such rare earth magnets are made of a sintered magnet manufactured by powder metallurgy and a plasti magnet fixed with an organic binder.
Sintered magnets are broadly classified into two types: Tsukumold magnets (hereinafter referred to as plastic magnets), but sintered magnets have the disadvantages of weak mechanical strength and poor dimensional accuracy, and to compensate for these disadvantages, plastic magnets are becoming more widely used. be.

Since such plastic magnets use synthetic resin, which is a non-magnetic material, as a binder, they have the disadvantage that their magnetic properties are inferior to those of sintered magnets. Therefore, in order to improve the magnetic properties of plastic magnets, it is necessary to increase the content of rare earth magnetic powder and increase the pressure during pressure molding to lower the porosity and improve the packing density of rare earth magnetic powder. .

However, in conventional rare earth plastic magnets, when the content of rare earth magnetic powder is high, the strength of the molded product before hardening and solidification is low, easily causing breakage and deformation, or the mechanical strength of the molded product after hardening is low. Because of this problem, if the pressurizing force is increased in order to reduce the porosity, a large load is placed on the mold during compression molding, which tends to cause damage to the mold.

[Means for solving problems]

In view of the above-mentioned problems of the prior art, the present invention aims to reduce the burden on the mold during molding, improve the magnetic properties by increasing the density of the molded product, and has high mechanical strength and dimensions. The purpose is to provide rare earth plastic magnets with excellent stability.

That is, the first aspect of the present invention is 50 to 95% intermetallic compound magnetic powder mainly composed of rare earth metals and transition metals, and the balance is a liquid thermosetting resin and the solid content of the liquid thermosetting resin is 100%.
The second aspect of the present invention is a permanent magnet material composition characterized by comprising 5 to 100 parts by weight of a plasticizer, based on the total weight of the magnetic powder. 50 to 95% by volume, with the remainder being a liquid thermosetting resin and 5 to 1 part by weight per 100 parts by weight of the solid content of the liquid thermosetting resin.
A method for molding a permanent magnet material composition, which comprises compression molding a permanent magnet material composition comprising 00 parts by weight of a plasticizer at room temperature, and then curing and solidifying it at the curing temperature of the liquid thermosetting resin. The content of each is as follows.

The intermetallic compound magnetic powder containing rare earth metals and transition metals as main components used in the present invention includes SmCo5, Sm2Co
+q, or magnetic powder known as a Nd-Fe-B alloy magnet, or other metals such as iron, zirconium, or other metals may be added to improve the magnetic properties. Among these, Co5 and Sm2CO+7-based magnetic alloys are preferred because they are industrially useful magnetic alloys in terms of oxidation resistance, low temperature coefficient, and high magnetic properties.

The intermetallic compound magnetic powder is in the form of a powder, but in order to improve the density of the compact and obtain high magnetic properties, the particle size distribution must be as wide as possible within the particle size range used. There is a need to. That is, the intermetallic compound magnetic powder that can be used in the present invention is preferably a mixture of particles with different sizes ranging from 1 μm to 11 μm. The maximum particle size in these particle groups can be appropriately selected depending on the minimum thickness of the intended molded article.

In order to obtain a composition such as the object of the present invention, it is necessary to bind the binder to the intermetallic compound magnetic powder more uniformly, and also to allow the binder itself to reduce the friction between the intermetallic compound magnetic powder during compression molding. It is important to have a role in mitigating the That is,
By using a liquid thermosetting resin as in the present invention (containing a plasticizer as a binder), the binder has a low viscosity and is not only uniformly distributed on the surface of the intermetallic compound magnetic powder, but also can be used during compression molding. Friction between intermetallic compound magnetic powders is reduced, a molded body with high packing density can be easily obtained, and magnetic properties are greatly improved. Furthermore, by using such a binder, even if the compression molding pressure is reduced, a molded product having the desired level of high density and high magnetic properties can be obtained, and the negative (U) against the molding die can be obtained. The value from an industrial point of view is sophisticated and high.

The liquid thermosetting resin used in the present invention is liquid at room temperature, and includes phenol resin, epoxy 4-1 resin, original resin + 34 resin,
Melamine resin, furan resin, unsaturated polyester resin,
Among others, phenolic resins, particularly resol type phenolic resins, are preferred.

The plasticizers used in the present invention include polyester plasticizers, phthalate ester plasticizers, epoxidized oil plasticizers, fatty acid ester plasticizers, and others, and are selected according to the type of liquid thermosetting resin used. do.

In particular, when using phenolic resin, adipic acid polyester plasticizer, phthalic acid polyester plasticizer,
Phosphate ester plasticizers, dibutyl phthalate, epoxidized soybean oil, and the like are very suitable.

The composition of the present invention is composed of an intermetallic compound magnetic powder and a liquid thermosetting resin containing a plasticizer, but if the intermetallic compound magnetic powder is less than 50% by volume, desired magnetic properties cannot be obtained.
On the other hand, if it exceeds 95% by volume, the mechanical strength decreases so much that it cannot be used practically. Furthermore, in the composition of the present invention, if the amount of plasticizer added is extremely small, the effect will not be noticeable; If a plasticizer is added, the mechanical strength of the molded product will be low (therefore, it is usually added in an amount of 5 to 100 parts by weight per 100 parts by weight of the solid content of the liquid thermosetting resin).
It is preferred to incorporate a range of parts by weight of plasticizer. Further, in order to improve the properties of the composition of the present invention, small amounts of cambling agents, lubricants, heat stabilizers, and other modifying additives may be added.

Compression molding methods such as hot pressing and cold pressing can be used to mold the composition described above, but since a liquid binder containing a plasticizer is used, the strength of the molded product after compression molding and before curing is high. Therefore, there is no need to employ a hot press that involves various operational troubles. That is, when molding the composition of the present invention, it is compressed and fixed molded at room temperature, and then cured and solidified at the curing temperature of the thermosetting resin used. By this method, it is possible to obtain a molded article with high productivity and also having good dimensional accuracy and magnetic properties. Suitable pressure conditions for compression molding are 2 to 8.
It is t/-. At a pressure of 2t/ad without grooves, the packing density achieved even with the composition of the present invention may be insufficient, and even if the pressure exceeds 8t/ad, the packing density is no longer noticeable. No significant improvement can be expected, and the burden on the mold becomes heavy, making the mold more likely to break. Furthermore, when heat-curing such a composition after molding, it is more preferable to heat-cure it in nitrogen or an inert gas in order to prevent deterioration of magnetic properties due to oxidation of the intermetallic compound magnetic powder. It is.

〔Example〕

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these in any way.

Examples 1-5 SmzCo+? 4N powder and 100 parts by weight of the solid content of the resol-type phenol resin, an adipic acid polyester plasticizer was added as shown in Table 1 (in the range of 30 to 90 parts by weight). Each composition was obtained by mixing with 20% by volume of resin.This composition was molded at room temperature under the pressure shown in Table 1 to form 1(1+nφ×
A cylindrical fixed molded body of 8 cranes was made. Thereafter, the molded body was heated and cured at 180° C. for 2 hours under nitrogen to obtain a molded body sample having a good external shape. The results of measuring the magnetic properties of the molded body samples with a B-H tracer and the density of the molded body samples are shown in Table 1, and all samples showed good values.

Examples 6 to 8 Cylindrical molded bodies were obtained in the same manner as in Example 2, except that 60 parts by weight of phthalic acid polyester, dibutyl phthalate, or phosphate ester was used instead of the adipic acid polyester plasticizer. . The results are shown in Table 1, with no chips or cracks in appearance, and good values for iffffability and density.

Comparative Example 1 A cylindrical molded body was obtained in the same manner as in Example 2, except that only the liquid resol resin was mixed without mixing the adipic acid polyester. The results are shown in Table 1, and although the external dimensions were good with no chips or cracks, the density of the molded product was low and (BH) max was small, giving unsatisfactory results.

Comparative Examples 2-3 Molding was carried out in exactly the same manner as in Example 2 except that a novolac type phenol resin was used and no plasticizer was contained.

In Comparative Example 2, the molding pressure was 2t/c+a, but the strength of the fixed molded body was extremely unsatisfactory, and no sample could be obtained for magnetic property evaluation. On the other hand, in Comparative Example 3, the molding pressure was 5t/
cJ, but the density and (BH) max of the molded product were extremely unsatisfactory, and there were many chips.

[Action and effect]

As described in detail above, according to the present invention, it is possible to provide a rare earth plastic magnet with high density, high magnetic properties, and excellent mechanical strength and dimensional accuracy with good productivity. The darning composition and the molded product obtained from it have a good balance of moldability, strength, dimensional accuracy, and magnetic properties, and can be used as precision small magnets such as field stones for small motors and correction magnets for TVs. can do.

Claims (1)

[Claims] 1. 50 to 95% by volume of intermetallic compound magnetic powder containing rare earth metals and transition metals as main components, the balance being a liquid thermosetting resin, and the solid content of the liquid thermosetting resin being 100% by weight. 5 for part
1. A permanent magnet material composition comprising ~100 parts by weight of a plasticizer. 2. The plasticizer is at least one of polyester plasticizers, phthalate plasticizers, and phosphate plasticizers.
A composition according to claim 1, wherein the species is selected. 3. The composition according to claim 1 or 2, wherein the intermetallic compound magnetic powder is a mixture of particles having different sizes in the range of 1 μm to 1 mm. 4. 50 to 95% by volume of intermetallic compound magnetic powder containing rare earth metals and transition metals as main components, the balance being a liquid thermosetting resin, and 5 parts by weight based on 100 parts by weight of the solid content of the liquid thermosetting resin.
A method for molding a permanent magnet material composition, which comprises compression molding a permanent magnet material composition comprising ~100 parts by weight of a plasticizer at room temperature, and then curing and solidifying it at the curing temperature of the liquid thermosetting resin. . 5. The molding method according to claim 4, wherein the compression molding is performed under pressure conditions of 2 to 8 t/cm^2. 6. The molding method according to claim 4, wherein the curing is carried out in nitrogen or inert gas.