JPH06204017A - Resin bond type magnet - Google Patents

Abstract

PURPOSE:To provide a resin bond type magnet of high cost performance by effectively kneading magnetic powder and resin which constitute a resin bond type magnet and by providing granular powder which can be filled into a molding die stably and surely. CONSTITUTION:Thermosetting resin containing two or more kinds of setting agents of different setting velocities are used as a binder of resin bond type magnet. Thereby, although resin is in the state of low viscosity and high kneading efficiency during kneading, a part of fast setting velocity thereof sets as time goes by passing through kneading and granule manufacturing processes, and strength of granule is raised and charge property to a die can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-bonded magnet.

[0002]

2. Description of the Related Art At present, resin-bonded magnets produced by compression molding are generally made of epoxy resin as a binder. In order to use an epoxy resin as a binder, a curing agent that cures the resin is required, which includes amine curing agents, polyamide curing agents, acid and acid anhydride curing agents, imidazole curing agents, etc. There is. These curing agents are used properly according to the characteristics such as the control of the curing speed of the resin, the mechanical strength of the cured product, the electrical properties, the heat resistance, and the chemical resistance. When used as a binder, the epoxy resin used as the base Generally, one type of curing agent is generally used.

Epoxy resin may be liquid at room temperature, solid, or an intermediate thereof, but when it is used as a binder in the production of compression molded magnets, it is judged from the magnetic properties of the magnet. As far as possible, it is considered best to use liquid resin. This is because the resin acts as a lubricant when the magnetic powder containing the resin is put into the molding die and molded, so that the density of the molded body becomes high.

When the liquid epoxy resin is used, the magnetic powder and the epoxy resin are kneaded for a long time in a shearing device such as a roll mill or a kneader. The obtained powder after addition of resin has agglomeration between powders and stickiness due to resin, and it is not possible to fill the powder immediately after kneading into the molding die as it is and mold it. It is necessary to be able to fill the mold.

However, the problem here is the strength of the granules. If the strength is weak, the granules will be broken during the filling work into the mold and the filling cannot be done as expected. In other words, the granules need some strength. In this case, it is the viscosity of the epoxy resin that gives the strength of the granules. If the viscosity is high, the strength increases and it is possible to obtain granules that are not easily broken. Granules break when filling the mold. Therefore, even if it is called a liquid epoxy resin, it is necessary to use an epoxy resin having a somewhat high viscosity. However, it is a very difficult work to knead a high-viscosity epoxy resin and magnetic powder and to uniformly disperse them throughout the magnetic powder so that a sufficient lubricating action can be obtained during molding.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem, and its object is to use an epoxy resin resin containing two or more kinds of curing agents as a binder for a resin-bonded rare earth magnet. This is to provide a resin-bonded magnet with high molding efficiency and high density.

[0007]

The present invention is characterized in that an epoxy resin resin containing two or more kinds of curing agents is used as a binder for a resin-bonded rare earth magnet.

The curing reaction when an amine-based curing agent is used as the curing agent is as follows.

[0009]

[Chemical 1]

[0010]

[Chemical 2]

[0011]

[Chemical 3]

In terms of reaction rate, the reaction of Chemical formula 1 is the fastest, and ethylenediamine, 1,3 diaminopropane, 1,
In the case of an aliphatic primary amine such as 4-diaminobutane or hexamethylenediamine, it cures at room temperature. On the other hand, acid anhydrides such as dodecenyl succinic anhydride, (DDSA), methyltetrahydrophthalic anhydride (Me-THPA), methylhexahydrophthalic anhydride (Me-HHPA), and phthalic anhydride (PA) are used as curing agents. In that case, since it does not cure at room temperature, it must be heated to a temperature of 100 ° C. or higher.

(Epoxy resin handbook: Nikkan Kogyo Shimbun) When a primary amine is used as a curing agent, the reaction amount thereof is defined by the amount of active hydrogen contained in the amine as shown in Chemical formula 1. Therefore, when a small amount of primary amine is added to all epoxy groups in the epoxy resin, a curing reaction occurs by leaving it at room temperature for several hours. However, this means that a resin containing an uncured component is obtained due to a partial curing reaction, which can be regarded as a state in which the viscosity of the resin is increased. Next, an acid anhydride is added to cure the remaining epoxy groups. However, this does not cure at room temperature and needs to be heated in order to cure it, and at room temperature it is in the same state as a high-viscosity epoxy resin. That is, by using a primary amine and an acid anhydride together as a curing agent, it is possible to obtain a resin that has a low viscosity immediately after the addition of the curing agent and has increased viscosity in a few hours, and has no viscosity change thereafter.

Since the resin bond has a resin containing a curing agent having a different curing rate as a binder for the magnet, the magnetic powder and the resin are in a low viscosity state when kneaded, and the kneading property is good, and when granulated. Due to the partial curing reaction, a high viscosity state is achieved, and the strength of the granules is strengthened, enabling stable filling in the mold.

The present invention will be described in detail below with reference to examples.

[0016]

【Example】

(Example 1) A rare earth magnet cast alloy of Sm2Co17 type was crushed by a jaw crusher, a pin mill and a ball mill in a nitrogen atmosphere, and classified by a sieve having an opening of 150 µm. Epicoat 827 (trade name of Yuka Shell Epoxy Co., Ltd.) and diethylenetriamine 0.5 phr, Me-THPA8 were added to the obtained powder of 150 μm or less (average particle size 40 μm).
2.5 wt% of 0 phr of the mixed solution was added. After addition
Knead for 1 hour with a kneader, and use an extruder and rectifier for about 0.5 m
m granules were obtained. Granules immediately after production, after 6H, after 24H,
The compressive fracture strength after 72H was measured. The results are shown in Table 1. The value is the load required for breaking (g).

Further, after the kneading, the dispersion of the filling property was compared for the molding powder having the outer diameter of 16 mm, the inner diameter of 14 mm, and the filling depth of 15 mm with the granulated powder of 24H. The filling property was determined by putting the granular powder in a ring having a diameter of 40 mm, and reciprocating the filling process twice on the mold, and judging by the weight of the powder entering the mold every five times. For comparison, the same experiment was carried out as a conventional method using a granular method using an epoxy resin not containing diethylenetriamine.

The results are shown in Table 2.

[0019]

[Table 1]

[0020]

[Table 2]

As can be seen from Table 1, the addition of the amine-based curing agent increased the strength of the granules after about 6 hours to about 1.6 times that of the product without the granules. In addition, it can be seen from Table 2 that the packing property is stable due to the increased strength of the granules.

(Embodiment 2) Nd-Fe by the quenched ribbon method
B-type rare earth magnet powder (average particle size 95 μm) was crushed by a jaw crusher, a pin mill and a ball mill in a nitrogen atmosphere, and classified by a sieve having an opening of 150 μm. 2.0 wt% of a mixture of Epicoat 827 (trade name of Yuka Shell Epoxy Co., Ltd.), 0.4 phr of triethylenetetramine and 130 phr of dodecenyl succinic anhydride was added to the obtained powder of 150 μm or less (average particle diameter of 32 μm). . After the addition, the mixture was kneaded with a kneader for 1 hour, and granules of about 0.5 mm were obtained with an extruder and a rectifier. Granules immediately after production, after 6H, 2
The compressive fracture strength after 4H and 72H was measured. The results are shown in Table 3. The value is the load required for breaking (g).

Further, after the kneading, the dispersion of the filling property was compared with the molding powder having the outer diameter of 16 mm, the inner diameter of 14 mm and the filling depth of 15 mm with the granulated powder of 24H. The filling property was determined by putting the granular powder in a ring having a diameter of 40 mm, and reciprocating the filling process twice on the mold, and judging by the weight of the powder entering the mold every five times. For comparison, the same experiment was carried out for the conventional method in which the epoxy resin not containing triethyltetramine was also used to make a granule.

The results are shown in Table 4.

[0025]

[Table 3]

[0026]

[Table 4]

As can be seen from Table 3, by adding the amine-based curing agent, the strength of the granules after 6 hours was about 1.5 times that of the product without the granules. In addition, it can be seen from Table 4 that the packing property was stable due to the increased strength of the granules.

(Embodiment 3) Nd-Fe by the quenching ribbon method
B-type rare earth magnet powder (average particle size 95 μm) was crushed by a jaw crusher, a pin mill and a ball mill in a nitrogen atmosphere, and classified by a sieve having an opening of 150 μm. 2.0 wt% of a mixture of Epicoat 827 (trade name of Yuka Shell Epoxy Co., Ltd.), 0.4 phr of triethylenetetramine and 130 phr of dodecenyl succinic anhydride was added to the obtained powder of 150 μm or less (average particle diameter of 32 μm). . After the addition, the mixture was kneaded with a kneader for 1 hour, and then kneaded with an extruder and a rectifier to about 0.
5 mm granules were obtained. Granules immediately after production, 6H, 24H
Then, the compressive fracture strength after 72H was measured. The results are shown in Table 5. The value is the load required for breaking (g).

After kneading, the outer diameter of the granulated powder of 24H is 16
A resin-bonded magnet having an inner diameter of 14 mm, an inner diameter of 14 mm and a thickness of 5 mm was molded and the density was measured. For comparison, the same experiment was carried out for a conventional method in which granules were formed using Epicoat 834 (trade name of Yuka Shell Epoxy Co., Ltd.) as a base resin.

The results are shown in Table 6.

[0031]

[Table 5]

[0032]

[Table 6]

As can be seen from Table 5, the strength of the granules became about 1.7 times after 6 hours by the addition of the amine-based curing agent as compared with immediately after the production. Further, it can be seen from Table 6 that the density of the molded product is higher in the present invention having a lower resin viscosity during kneading.

[0034]

INDUSTRIAL APPLICABILITY As described above, the use of the present invention makes it possible to obtain a raw material granule powder for a resin-bonded magnet which can be highly densified and has an excellent filling property, and as a result, a resin-bonded magnet having a high cost performance You can get a magnet.

Claims (4)

[Claims] 1. A resin-bonded magnet, wherein a thermosetting resin containing two or more kinds of curing agents having different curing rates is used as a binder in the production of the resin-bonded magnet. 2. The resin-bonded magnet according to claim 1, wherein a rare earth magnet alloy is used as a magnet raw material. 3. The resin-bonded magnet according to claim 1, wherein an alloy containing a rare earth metal and iron as a main component is used as the rare earth magnet alloy. 4. The resin-bonded magnet according to claim 1, wherein the rare earth magnet alloy is an alloy containing a rare earth metal, iron and nitrogen as main components.