JPS60220920A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To enable to increase the filling amount of magnet powder as well as to improve its orientation property and to obtain a highly efficient resin-bonded magnet by a method wherein the magnet powder with its surface covered with a lubricant and a thermosetting resin are mixed and a press molding is performed on the mixture in a magnetic field. CONSTITUTION:A lubricant, such as aliphatic carboxylic acid, aliphatic family carboxylic acid ester, resin carboxylic acid amide and so forth, is coated on the surface of rare earth magnet powder consisting of a lanthanum family metal and a transition metal. At this time, the amount of the lubricant, which is used for the coating, is selected at a ratio of 0.05-0.6wt% to that of the magnet powder in consideration of strength, heat resistance and so forth, and the lubricant is coated while being made to disperse in solvent. After the coating was over, the solvent along is made to heat-evaporate. After that, 20wt% of epoxy resin is added to this magnet powder, both is mixed and the mixture is molded by press in a magnetic field. According to such a way, the friction between the powder and the resin and the friction between the powder-powder at the time of press molding are lowered, the filling amount of the magnet powder is increased and the residual magnetic flux density and the square type property are improved. Accordingly, a high energy product is obtained.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for producing a permanent magnet obtained by press-molding a mixture of magnet powder coated with a lubricant and a thermosetting resin in a magnetic field. .

[Prior art]

Permanent magnets can be roughly divided into two types: sintered type and resin bonded type.
There are two types. A feature of sintered magnets is their high energy product. On the other hand, resin bonded magnets are divided into two types depending on whether a thermosetting resin or a thermoplastic resin is used for the bonding resin. Permanent magnets using thermoplastic resin have excellent mechanical strength, but the maximum energy product (hereinafter abbreviated as BE > max) is '7~8 (MGoe) even when rare earth magnet powder is used and is 7'c. Permanent magnets using thermosetting resin are
Because it requires less resin, its (BH > max) is more than twice that of magnets using thermoplastic resin, and it is currently attracting a lot of attention due to its good mechanical properties and ease of molding. Resin-bonded permanent magnets using curable resin (hereinafter simply referred to as resin-bonded permanent magnets) are conventionally made by simply kneading magnet powder crushed to an appropriate particle size and thermosetting resin. The material had the drawbacks of low density and magnetic performance that was still considerably lower than that of sintered magnets, so it was not used in applications that required high performance.

〔the purpose〕

The present invention aims to improve the performance of the resin-bonded magnet by coating the surface of the magnet powder with a lubricant in order to improve the above drawbacks.

〔overview〕

When a lubricant is coated on the surface of the magnet powder, this lubricant layer formed on the powder surface reduces the powder-resin and powder-powder friction that occurs during press molding, increasing the amount of magnet powder packed and improving orientation. This improves the performance of the magnet.

The lubricants coated on the surface of the magnet powder include aliphatic carboxylic acids, aliphatic carboxylic acid esters, and aliphatic carboxylic acid amides.

The Ich formula of this aliphatic carboxylic acid is generally represented by ROOOH, where R represents a hydrocarbon group f. In addition to saturated hydrocarbon groups such as alkyl groups in E, unsaturated hydrocarbon groups containing double bonds, hydrocarbon groups in which the hydrogen atom is replaced with a hydroxyl group (-OH), and Some have cyclic hydrocarbon groups. Also carboxyl group (-000H)
It also includes aliphatic dicarboxylic acids with two fs. Typical of these are caprylic acid, pelargonic acid,
These include myrinutic acid, palmitic acid, stearic acid, behenic acid, oleic acid, erucic acid, linoleic acid, linoleic acid, golulic acid, sabinic acid, lycylic acid, and tabusic acid.

Aliphatic carboxylic acid esters can be synthesized from the above-mentioned aliphatic carbonic acids and alcohols, and have the general formula ROOOR'. R' here represents an alkyl group.

There are many types of aliphatic carboxylic acid esters, including methyl esters, ethyl esters, and butyl esters of aliphatic carboxylic acids. Typical examples include methyl laurate, ethyl myristate, methyl stearate, trimethyl stearate, methyl oleate, and ethyl oleate.

Aliphatic carboxylic acid amide has a hydroxyl group (
-OH) is substituted with an amino group (-NH2), and is represented by the general formula R(!ON H2. Typical substances include caprylic acid amide, myristic acid amide, stearic acid amide, and oleic acid amide. Examples include amides.

On the other hand, the magnet powder used is a rare earth magnet powder of UR2TM+7 series, and the lanthanum metal element La containing R, Y,
ce, pr, Nd, Sm, zu,
Gd, Tb, Dy, HO, Br.

TM represents one type or a combination of two or more of Tm, Yb, and Lu, and TM represents a transition metal. This R2T
MI7-based magnet powder has higher magnetic performance than Sm0oy, alnico, and ferrite magnet powder, so it can be said to be suitable for resin-bonded magnets.

The appropriate amount of lubricant to be coated on the surface of the magnet powder is 0.05 to 0.6% by weight based on the magnet powder, and 0.05% by weight.
If it is less than % by weight, sufficient lubricity will not be obtained,
If it exceeds 0.6% by weight, the strength and heat resistance of the molded product will decrease. Furthermore, there are two methods for coating the surface of the magnet powder, as follows.

(α) Solvent slurry method In this method, the lubricant is dissolved in a suitable solvent (if it is liquid, it is mixed), then the magnet powder is dispersed in this solution,
A method of coating the surface of magnet powder with lubricant by evaporating the solvent while stirring.

(b) Direct cross-mixing method A method in which a lubricant is added to magnet powder and the system is mechanically coated using a cross-mixer (wheel-type mixer, blade-type mixer, etc.).

In both methods (a,) and (b), it is possible to quickly form a uniform coating layer by heating, reducing pressure, etc.

The permanent magnet of the present invention and its manufacturing method include forming a coating layer of a lubricant on the surface of magnetic powder, and then applying an epoxy resin to the surface of the magnetic powder.
It is characterized in that it can be obtained by adding the mixture in an amount of 4.0% by weight to cross-wire, and press-molding the cross-wire in a magnetic field.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples.

(Example 1) Sm(Coo, 6., Cu(,, CnFe(,, 3z
ro, o16)7. An alloy with a composition of 'g is melted in a high-frequency melting furnace to produce Inboratora. This ingot is subjected to solution treatment and heat treatment such as aging treatment, and then this ingot is ground in a ball mill to a size of about 2 to 80 μm. The obtained powder is coated with 15% by weight of the lubricant fO shown in Table 1 using a solvent slurry method. Thereafter, 2.0% by weight of epoxy resin is added to this powder, cross-mixing is performed, and the kneaded product is press-molded in a magnetic field. The magnetic performance of this molded article is shown in Table 2.

From Tables 1 and 2, samples 1 to 5 have significantly improved magnetic performance compared to the comparative example. This is because the density of the compact increases due to the lubricity of the aliphatic carboxylic acid, resulting in an improvement in residual magnetic flux density (hereinafter abbreviated as BT), and squareness 5Q (=H/1Hc), which represents the degree of orientation. This is due to the fact that the Thus, it can be said that aliphatic carboxylic acids are effective as lubricants in improving the performance of resin-bonded permanent magnets.

Table 2 (Example 2) Table 4 shows the magnetic performance of permanent magnets molded in the same manner as in Example 1 using aliphatic carboxylic acid esters shown in Table 6 as lubricants.

Also in the fourth case, compared to the comparative example, the magnet of the present invention has Bτ, S
It can be seen that both Q and Q are high. It can be said that aliphatic carboxylic acid esters are also effective as lubricants in improving the performance of resin-bonded permanent magnets.

Table 4 (Example 3) Table 6 shows the magnetic performance of permanent magnets molded in the same manner as in Example 1 using the aliphatic carboxylic acid amides shown in Item 5 as lubricants.

It can be seen from Tables 5 and 6 that the magnets of the present invention have higher magnetic performance than the conventional magnets. It can be said that aliphatic carboxylic acid amide is effective in improving the magnetic performance of resin-bonded permanent magnets.

Table 6 (Example 4) Using oleic acid as a lubricant and using an alloy shown by the composition formula in Table 7 as a magnet alloy, permanent magnets were manufactured in the same manner as in Example 1 and by the conventional method (without lubricant). Figure 1 shows the magnetic performance of the manufactured permanent magnet.

From FIG. 1, it can be seen that the magnet of the present invention has higher performance than the conventional method even if the magnet alloy is changed.

〔effect〕

As explained above, it can be said that the present invention overcomes the low performance that was a drawback of resin-bonded permanent magnets, and makes it possible to mass-produce high-performance resin-bonded magnets.

[Brief explanation of the drawing]

Figure 1 compares the magnetic performance of permanent magnets manufactured by the method of the present invention and by the conventional method when the magnetic alloy is scented.

Claims (1)

[Scope of Claims] (1) A method for producing a permanent magnet obtained by covering the surface of a magnet powder with a lubricant, kneading the magnet powder and a thermosetting resin, and then press-molding the mixed wire in a magnetic field. (2. Claims [ffl! In paragraph (1),
A method for producing a permanent magnet, characterized in that the lubricant used is an aliphatic carboxylic acid, an aliphatic carboxylic acid ester, or an aliphatic carboxylic acid amide. (6) In Paragraph 1 of the scope of the % Kozuki Blue Request, it is specified that R2TMI7-based magnet powder (coated with one or more lanthanum metal elements including RViY and TMld transition metal) is used as the magnet powder. Characteristic permanent magnet manufacturing method.