JPH0564442B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a ferromagnetic resin composition having high heat resistance. [Prior Art] Due to the high magnetic performance and good mechanical properties of resin-bonded rare earth permanent magnets, the production volume thereof has increased significantly in recent years. However, resin-bonded magnets are significantly inferior to sintered magnets in terms of heat resistance. For example, in the case of a system consisting of SmCo ₅ and epoxy resin,
Its usable temperature is 80℃, and the Curie point (Tc)
Even in the case of a system of Sm ₂ TM ₁₇ (TM is a transition metal mainly composed of cobalt) and epoxy resin, the usable temperature is only 120°C. For this reason, resin-bonded magnets have not been used until now in industrial motors, automobile parts, and other applications that require heat resistance. [Purpose] The present invention solves these problems,
The purpose is to provide a resin bonded rare earth permanent magnet having high heat resistance. [Summary] In general, changes in φ ₀ (open magnetic flux) of permanent magnets are classified into the following three types from the viewpoint of phenomena. (1) Reversible change If the state changes, the magnetic flux will change accordingly, but when the state returns, it will return to its original value. (2) Irreversible change Demagnetization that occurs when the magnetization in the direction of magnetization is reversed for various reasons, and returns to its original value when re-magnetized. (3) Permanent demagnetization Demagnetization that occurs due to physical or chemical changes and cannot be restored by re-magnetization. If a resin bonded magnet is left in high temperature for a long time,
As the adhesive force of the resin decreases, the bonding force between the resin and the magnet powder decreases, which may disturb the orientation of the magnet, or the resin itself deteriorates or decomposes, and the gas generated at that time damages the magnet powder. As a result, irreversible change and permanent demagnetization are greater than in sintered magnets. The structural formulas of poly-P-vinylphenol (hereinafter abbreviated as PHP) and brominated poly-P-vinylphenol used in the present invention are shown below. Poly-P-vinylphenol Brominated poly-P-vinylphenol The cured product obtained by blending PHP into an epoxy resin and curing it with heat has a glass transition point of over 200℃, and the adhesive strength does not decrease much at high temperatures. When used in bonded magnets, it can be said that irreversible changes and permanent demagnetization of the magnet can be kept low. Moreover, brominated poly-P-vinylphenol has flame retardancy, and it is also possible to improve the flame retardance of resin-bonded magnets. Combined with the great adhesion and good mechanical properties of epoxy resins, this
PHP-epoxy resin adhesives are highly suitable for resin-bonded magnets. [Examples] Hereinafter, the present invention will be described in detail based on Examples. Example 1 An alloy having a composition of Sm (Co _0.672 Cu _0.08 Fe _0.22 Zr _0.028 ) _8.2 is melted in Ar gas using a low frequency solution furnace. The alloy was liquefied at 1160°C for 10 hours, 800°C
Aging treatment for 4 hours at ℃. The alloy is then ground into powder with a particle size of 2 μm to 80 μm using a ball mill. 2% by weight of the resin having the composition shown in Table 1 was added to the magnet powder described above, and the mixture was kneaded using a kneader and then compression molded in a magnetic field. This molded body
Heate at 150°C for 1 hour to obtain a permanent magnet. (However, in Table 1, Epicote 828 represents epoxy resin, Resin M, MB represents PHP manufactured by Maruzen Co., Ltd. and its brominated product, and TTA represents triethylenetetramine.)

[Table] The obtained magnet was subjected to magnetic measurement using a B-H tracer and then processed into a cylindrical shape of φ10×7 mm. This sample is magnetized using the pulse method, and then left in a constant temperature bath at 150°C for 1000 hours. The thermal demagnetization test was conducted by measuring the total magnetic flux using the measuring device shown in FIG. In addition, the permeance coefficient of this sample is L/D=7/ since the anisotropy direction is 7 mm from the long axis direction.
10=0.7 and permeance coefficient=Bd/Hd≒2
becomes. Table 2 shows the irreversible demagnetization rate, and Table 3 shows the magnetic performance.

【table】

[Table] The table shows that the magnetic performance of the magnet of the present invention is almost the same as that of the comparative example, but the irreversible demagnetization rate is greatly improved. Example 2 FIG. 2 is a graph showing the magnetic performance and irreversible demagnetization rate when the amount of magnet powder packed into the resin of Sample 1 in Table 1 was changed. The magnet manufacturing method and testing method are the same as in Example 1. From the figure, below 90%, the magnetic performance mainly decreases,
Above 99%, it became difficult to mold the magnet. At this time, the coercive force did not change even if the filling amount of magnet powder was changed. Example 3 A permanent magnet is manufactured in the same manner as in Example 1. However, the resin used was Sample 1 to which zinc stearate was added as a metal soap. When zinc stearate is added to resin, its amount and magnetic performance,
The relationship with irreversible demagnetization rate is shown in FIG. Incidentally, even when zinc stearate was added, the coercive force did not change. Example 4 The alloy used in Example 1 is melted, solution treated, aged and ground in the same manner. 5% by weight of an adhesive having the composition of Sample 1 and Sample 2 shown in Table 1 is added to the obtained powder and kneaded. Table 5 shows the irreversible demagnetization rate and magnetic performance of the magnet obtained by transfer molding this kneaded material under the conditions shown in Table 4.

[Table] After 30 seconds of curing, the sample was taken out and post-cured at 170°C for 2 hours.

〔effect〕

As described above, the present invention has the effect of greatly improving the heat resistance of resin-bonded magnets.

[Brief explanation of the drawing]

Figure 1 shows the magnetic flux detection device used in the thermal demagnetization test used in the present invention. 1... Magnet sample, 2... Coil, 3... Measurement case (A), 4... Measurement case (B), 5... Digital magnetometer, Figure 2 shows the amount of magnet powder packed and magnetic performance. , a graph showing the relationship between irreversible demagnetization rate. Figure 3 is a graph showing the amount of zinc stearate added, the magnetic performance of the magnet, and the irreversible demagnetization rate.

Claims (1)

[Scope of Claims] 1. A ferromagnetic material comprising a mixture of at least one of poly-P-vinylphenol or brominated poly-P-vinylphenol, a thermosetting resin made of an epoxy resin, and rare earth magnet powder. Resin composition. 2 Add metal soap to the thermosetting resin as a lubricant.
The ferromagnetic resin composition according to claim 1, wherein the ferromagnetic resin composition is added in an amount of 10% by weight or less. 3. The ferromagnetic resin composition according to claim 1 or 2, wherein the rare earth magnet powder is 90 to 99% by weight, and the remainder is the thermosetting resin.