JPS63120407A - Manufacture of plastic magnet - Google Patents

Abstract

PURPOSE:To obtain a plastic magnet having a high degree of orientation in a magnetic field of relatively low intensity, by supplying a compound consisting of magnetic powder and a plastic resin binder to a magnetic field press molding machine after premagnetizing it and press molding the compound while orientating it with the magnetic field. CONSTITUTION:A compound consisting of magnetic powder and a plastic resin binder is premagnetized and supplied to a magnetic field press molding machine, by which the compound is press molded while orientated in the magnetic field. For example, a rare earth magnet having an inflection point of 5 kOe in an initial magnetization curve is crushed into powder with a grain size of 10-30 mum. 4 parts by weight of liquid epoxy resin, 0.2 parts by weight of oxidizing catalyst and 15 parts by weight of aceton are added to 100 parts by weight of the powder and they are stirred and mixed well. The mixture is then dried under a reduced pressure at about 50 deg.C to remove aceton and a compound is obtained. This compound is magnetized by pulse magnetic field of 30 kOe, and then press molded under a pressure of 1000 kg/cm<2> while it is orientated with the magnetic field, at a magnetic field intensity of 5-15 kOe. The magnet, after demagnetized, is taken out of the molds and heated in an oven at a temperature of 150 deg.C so as to accelerate hardening thereof.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a plastic magnet made of magnet powder and a plastic resin binder by magnetically oriented press molding, and the orientation rate of the plastic magnet is significantly increased. The purpose is to provide improved molded products.

(Prior Art and Problems) Conventionally, as a method for manufacturing a plastic magnet using 1 m stone powder, a method has been known in which a mixture consisting of the powder and a plastic resin binder is press-molded in a magnetic field at room temperature.

In this case, it was not possible to obtain a high orientation rate for the plastic magnet, and efforts were made to increase the magnetic field strength during press molding, but this had its limits and the device structure was complicated to increase the magnetic field strength. In addition, there are other problems such as high cost, and there has been a demand for improvements in the manufacturing method of plastic magnets.

(Structure of the Invention) As a result of intensive research on the magnetic field strength during magnetic field orientation press molding, the present inventors obtained a plastic magnet with a high orientation rate with a relatively low magnetic field strength, without requiring a high magnetic field strength as in the past. It was very successful.

That is, the gist of the present invention is a method for manufacturing a Plus Deck magnet, in which a compound consisting of magnet powder and a plastic resin binder is magnetized in advance, then supplied to a magnetic field press molding machine, and then subjected to magnetic field orientation press molding.

The present invention will now be described in detail.

The magnetic powder used in the present invention is RCo 5*R2
These include CO17 (in the formula, R represents an upper class element) type outer class magnet and ferrite magnet, but in particular, as shown in Figure 1, the inflection point in the initial magnetization curve is 3 KOe.
More effective against the above, R2C017
suitable for the type.

Next, as the plastic resin binder of the present invention,
Thermosetting resins such as epoxy resins, polyester resins, silicone resins, melamine resins, polyethylene resins,
Thermoplastic resins such as polypropylene resin, polyvinyl chloride resin, nylon resin, thermoplastic polyester resin, polycarbonate resin, polyacetal resin, and fluororesin are used.

In the present invention, the magnetic powder and the plastic resin binder may be thoroughly mixed to obtain a bound shape.
At this time, if necessary, use aromatic compounds such as benzene, l-luene, and xylene, ketone compounds such as acetone and methyl ethyl carbon, alcohol compounds such as methyl alcohol, ethyl alcohol, and propyl alcohol, methyl acetate, and acetic acid. Organic solvents such as esters such as ethyl can be used.

The mixing ratio of the magnet powder and the plastic resin binder is not particularly limited, but from the viewpoint of orientation rate, it is 20 parts by weight or less of the plastic resin binder per 100 parts by weight of the magnet powder,
Preferably it is in the range of 2 to 10 parts by weight. In addition, when an organic solvent is used, it is preferable to remove the organic solvent by heat drying or vacuum drying.

The thermoplastic resin described above can be in the form of granules, powder, or flakes without any restrictions, and may be heated as appropriate when mixed with magnet powder. The temperature may vary depending on the type of resin, but generally the temperature may be higher than the softening temperature or pour point of the resin.

In the present invention, the compound consisting of the magnet powder and plastic resin binder obtained above is magnetized in advance and oriented in a mechanical manner, but the magnetic field strength in this case is 1.
The amount should be 5 KOe or more, preferably 20 KOe or more.Next, the pre-magnetized compound is supplied to a magnetic field press molding machine, and then magnetic field oriented press molding is performed.
In this case, the magnetic field strength is 15 KOe or less, preferably in the range of 3 to 15 KOe, and the applied pressure is 100 to 15 KOe.
Range of 4000Kg/crn', preferably 300-2
000Kg/crrf.

In addition, during press molding, it is possible to heat or cool as necessary, and the molded product obtained after press molding may be further heat-treated. Since the product uses a pre-magnetized compound during magnetic field orientation press molding, it has the advantage of having higher magnetic properties, especially higher orientation rate, than conventional products.

According to the method of the present invention, the magnetically oriented press molding machine uses a pre-magnetized compound, so it is possible to lower the magnetic field strength than conventional ones, which eliminates undue burden on the equipment structure and improves productivity. This has the advantage of contributing to improvement.

Next, an example will be given.

Example 1 A rare earth magnet (with an inflection point of 5 KOe in the initial magnetization curve)
Shin-Etsu Chemical Co., Ltd. product name R-30) with plain particle size 10
It was ground to a powder of ~30 Ji, m. To 100 parts by weight of this powder were added 4 parts by weight of liquid epoxy resin (trade name: Ebiko 828, manufactured by Shell Kagaku Co., Ltd.), 0.2 parts by weight of a curing catalyst (trade name: C17Z, manufactured by Shikoku Kasei Co., Ltd.), and 15 parts by weight of acetone. After thorough stirring and mixing, acetone was removed by drying under reduced pressure at about 50°C to obtain a compound.

This compound was magnetized with a pulsed magnetic field of 30 KOe and then subjected to magnetic field orientation press molding.

The pressure in press molding was lOOOKg/am'', and the magnetic field strength was 5KOe, 7.5KOe, 10KOe, and 15KOe, respectively, and magnetically oriented press molding was carried out.
No.

Plastic magnets 1 to 6 were obtained. Next, this plastic magnet was demagnetized, taken out from the mold, and heated in an oven at 150° C. for 1 hour to accelerate curing. The properties of this plastic magnet were measured and the results are shown in Table 1.

For comparison, the results of samples without preliminary magnetization treatment and with magnetic field strengths of 0.10 and 15 KOe during molding are also listed in the same table as comparative and reference examples.

Example 2 A clay magnet SmCO5 with a plain particle size of lO~301Lm
ground into powder. To 100 parts by weight of this powder, 4 parts by weight of liquid 1-boxy resin (trade name: Epicoat 828 manufactured by Shell Chemical Co., Ltd.), and 4 parts by weight of a curing agent (trade name: C17Z, manufactured by Shikoku Kasei Co., Ltd.)
After adding 0.2 parts of acetone and 15 parts of acetone and thoroughly stirring and mixing, the acetone was removed by drying under reduced pressure at about 50°C to obtain a compound.

After magnetizing this compound with a pulsed magnetic field of 30 KOe, it was subjected to magnetic field orientation press molding.

Pressure during press molding is 1000 Kg/ern'
Then, a magnet was produced by magnetic field orientation press molding 17 with a magnetic field strength of 10 KOe, which was demagnetized, taken out from the mold, and heated 17 in an oven at 150° C. for 1 hour to accelerate hardening.

The properties of this plastic magnet were measured and the results are shown in Table 2 together with Comparative Example 1.2.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram showing a dynamic magnetization curve and a hysteresis curve of a magnet. Patent Applicant: Shin-Etsu Chemical Co., Ltd. Procedural Amendment December 10, 1985 [1] Indication of the case Patent Application No. 267267, filed in 1988 2. Name of the invention Method for manufacturing plastic magnets 3. Person making the amendment Case and Relationships Patent applicant name (206) Shin-Etsu Chemical Co., Ltd. 4. Agent “spontaneous” 6. Column 7 of “Detailed description of the invention” of the specification to be amended, Contents of the amendment

Claims (1)

[Scope of Claims] 1. A method for producing a plastic magnet, which comprises magnetizing a compound consisting of magnet powder and a plastic resin binder in advance, supplying it to a magnetic field press molding machine, and then carrying out magnetic field orientation press molding. 2. The method for manufacturing a plastic magnet according to claim 1, wherein the magnet powder has an inflection point of 3 KOe or more in the initial magnetization curve.