JPH02109308A - Resin bond type permanent magnet and its manufacture - Google Patents

Abstract

PURPOSE:To enhance the anti-rusting property by forming a resin layer due to electrodeposite coating on the surface of a molding chiefly containing magnetic powder specified and a synthetic resin as the binder. CONSTITUTION:A molding is formed chiefly from a magnetic powder to be expressed as R-T-B (where R is Nd or Nd partially substituted with rare earth elements, and T is Fe or Fe partially substituted with transition metals) and a synthetic resin as the binder. This molding is dipped in a water soluble coating, and DC current is supplied between the molding and its counter electrode with the molding used as either positive or negative electrode, and thereby coatings are electrically applied to the whole molding. This is followed by heating to achieve a resin layer over the surface of molding. Thus a resin bond type permanent magnet is obtained with the anti-rusting property enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a resin-bonded magnet and a method for manufacturing the same, and more specifically to a resin-bonded magnet that prevents oxidative deterioration during use and that is suitable for mass production. The present invention relates to a method for manufacturing the magnet.

[Prior art 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, so they have been used in a wide variety of fields in recent years. However, it has the disadvantage of being easily oxidized, and this tendency is particularly noticeable in NdFe-B magnets. A resin-bonded magnet in which such rare earth magnetic powder is fixed with a synthetic resin binder has a problem in that its magnetic properties deteriorate over time due to oxidation when the environment in which it is used is a high-temperature atmosphere.

In order to overcome this problem, Japanese Patent Application Laid-Open No. 61-18480
As described in No. 4, a method has been proposed in which rare earth magnetic powder is coated with a 4M polymer resin. However, although the above method has a certain degree of oxidative deterioration prevention effect, it is difficult to say that it is fully satisfactory in practice. It is very difficult to form a film with good adhesion (
2) Practically sufficient corrosion resistance cannot be obtained due to reasons such as the resin coating film being easily separated during molding.

[Means for solving the problem] In view of the above-mentioned circumstances, the present inventors have conducted intensive research and found that after molding a mixture of rare earth magnetic powder and synthetic resin, a mixture of rare earth magnetic powder and synthetic resin is coated with a multi-machine coating to achieve uniform and adhesive properties. The present invention was completed by discovering that a good resin (8 film) is formed on the surface and the above problem is solved.

That is, the first aspect of the present invention is represented by R-T-B (R is Nd or a part thereof substituted with a rare earth element, T is Fe or a part thereof substituted with a transition metal). The present invention provides a resin-bonded permanent magnet characterized by having a resin layer formed by electrodeposition coating on the surface of a molded body consisting of a magnetic body and a synthetic 4M resin as a binder. 2 is a magnetic powder represented by RT-11', (T? is Nd or a part thereof substituted with a rare earth element, T is Fa or a part thereof substituted with a transition metal). , by immersing a molded body whose main component is a synthetic resin as a binder in a water-soluble paint, and supplying a direct current between the molded body and a counter electrode using the molded body as an anode or a cathode. Each of these describes a method for manufacturing a resin-bonded permanent magnet, which is characterized in that the entire body is electrically coated and then heated to form a resin layer on the surface of the molded body.

The magnetic powder used in the present invention is R-"1-B (R is N
d or a part thereof is replaced with a rare earth element, T is Fe
or partially substituted with a transition metal) and unavoidable impurities, and the particle size is mostly I to 5.
00 μmO) range is preferable. If it is less than 1 .mu.m, it is likely to catch fire during the manufacturing process or the magnetic properties will deteriorate due to oxidation, while if it exceeds 500 .mu.m, the filling rate will decrease and sufficient feelability will not be obtained.

, G: The synthetic resin as an antagonist used in the investigation is appropriately selected from commonly used angular plastic resins, thermosetting resins, or rubbers, taking into consideration the molding method.

Examples of thermosetting resins as binders used in the present invention include phenolic resins, epoxy resins, and melamine resins, and examples of thermoplastic resins include nylon 6 and nylon 12.
Examples include polyamides such as polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyesters, and polyphenylene sulfide.

The blending ratio of the above 11 magnetic ↑ 51 bodies and synthetic resin is as follows:
90 parts by volume of the synthetic resin for 10 to 95 parts by volume of the 451 sex substance
The plasticizer is preferably used in an amount of 0 to 10 parts by volume, and commonly used additives such as lubricants, heat stabilizers, flame retardants, and other modifiers may also be added.

Examples of methods for molding the magnetic powder and resin binder mixture used in the present invention include compression molding, injection molding, extrusion molding, and calender molding.

In the electrodeposition coating method used in the present invention, a molded product obtained by molding a mixture of magnetic powder and synthetic resin is immersed in a water-soluble paint, the molded product is used as an anode or a cathode, and the molded product is used as an anode or a cathode. This is a coating method in which a direct current is supplied between the molded body and the counter electrode, the molded body is electrically coated, and then a resin coating is formed on the surface of the molded body by heating, and the molded body is used as an anode. An anion electrodeposition coating method or a cation electrodeposition coating method using the molded body as a cathode can be employed.

The resins used in the above anionic electrodeposition coating are drying oil,
It is a polycarboxylic acid resin with a backbone of polyester, polybutadiene, epoxy ester, polyacrylic acid ester, etc., and is usually neutralized with an organic amine or a base such as caustic potash, and then turned into an aqueous solution or dispersion to produce a negative
RN.

The resin used in the above cationic electrodeposition coating is mainly a polyamino resin with a backbone of epoxy resin, acrylic resin, etc., and is usually neutralized with an organic acid and turned into an aqueous solution or dispersion to become positively charged. . Furthermore, for the purpose of improving rust prevention and reinforcing the paint film, the above resin may contain rust preventive pigments such as zinc oxide, zinc chromate, strontium chromate, red lead, or benzotriazole. It may be included.

The thickness of the electrodeposition coating film in the present invention is preferably 4 to 50 μm. If it is less than 4 μm, the i'i4 oxidation property is not sufficient, and if it exceeds 50 μm, the distance from the magnet surface becomes large, so that the magnetic force that can be effectively used is limited and sufficient magnetic properties cannot be obtained. In addition, it is also good to perform a surface treatment on the surface of the molded body before electrodeposition coating, and the surface treatment includes surface conditioning treatment such as acid treatment or alkali treatment 1, Zn, Ni, Cr.
, Cu plating treatment, zinc phosphate treatment, manganese phosphate treatment, chromic acid treatment, etc. are preferred.

〔Example〕

The present invention will be explained below with reference to Examples and Comparative Examples.
The present invention is not limited in any way by these.

Comparative Example 1 A mixture of 80% by volume of NdFeB-based powder (manufactured by General Motors) and 20% by volume of resol type phenol resin was mixed and the mixture was stirred at room temperature to produce 5 ton/cd.
The synthetic resin was cured under the conditions of 190° C. for 2 hours to obtain a ring-shaped molded product A-1 having an outer diameter of 8 shafts, an inner diameter of 6 mm, and a height of 4 1.

Comparative Example 2 Comparative Example 1 except that Nd-Fe-B, v+ Yusei Kabo was infiltrated in a solution prepared by diluting epoxy resin to 5% with methyl ethyl ketone for 4 minutes, then taken out from the solution and the resin was cured.
A ring cane molded body-2 was obtained under the same molding conditions as in Example 1.

Example The molded product obtained in the above comparative example was subjected to electrodeposition coating to obtain molded product B-f~3. The molded body was immersed in a 1% alkaline solution as an electrodeposition device +iii, and then subjected to electrodeposition coating.

"Nileclone" (trade name, manufactured by Kansai Paint Co., Ltd.) was used as the electrodeposition paint, and the electrodeposition voltage was 140V (sample B-1).
), 160V (Sample B-2), 180V (Sample B-3), and then 170°C
Heating was performed for 1 minute.

The antirust performance of the resin-bonded magnets obtained by the operations beyond the evaluation test was evaluated by the following method.

(1'l Environmental Test: Using a high-temperature high-temperature tester, the above-mentioned molded body was left standing in an atmosphere of 80° C. and 95% RH, and the appearance was inspected every 24 hours.

(2) The molded article was placed in sulfuric acid (mol/I), and bubbles generated near the outer surface were observed every 5 minutes.

The λ・F value is shown in Table 1.

No. table A-10 Δ i4, rating in Table 1 (6:! The following criteria were followed.

○ Very little rust 1 - Significant bubble formation Significant bubble formation type permanent magnet can be provided.

Patent applicant Kanebuchi Chemical] Nigyo Co., Ltd.

Claims (2)

[Claims] 1. Synthesis of magnetic powder represented by R-T-B (R is Nd or a part thereof replaced with a rare earth element, T is Fe or a part thereof replaced with a transition metal) and a binder. 1. A resin-bonded permanent magnet characterized by having a resin layer formed by electrodeposition coating on the surface of a molded body whose main constituent is resin. 2. Synthesis of magnetic powder represented by R-T-B (R is Nd or a part thereof replaced with a rare earth element, T is Fe or a part thereof replaced with a transition metal) and a binder. A molded body whose main constituent is resin is immersed in a water-soluble paint, and the entire molded body is electrically painted by using the molded body as an anode or a cathode and supplying a direct current between the molded body and a counter electrode. A method for producing a resin-bonded permanent magnet, which comprises heating the molded body after heating to form a resin layer on the surface of the molded body.