JPH07122418A - Resin-bonded magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide the title resin-bonded magnet having high strength, density and performances and the manufacturing method thereof. CONSTITUTION:The title resin-bonded magnet is molded out of a magnet composition comprising a mixture of coupled magnetic particles, a thermosetting resin or themoplastic resin and an additive. Through these procedures, the title resin coupled magnet having high strength, density and performances can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to small motors, actuators, encoders used in electronic devices,
The present invention relates to a resin-bonded magnet used for a sensor and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventional resin-bonded magnets are prepared by directly mixing a magnetic powder of an inorganic material and a thermosetting resin of an organic material or a thermosetting resin and an additive, granulating and sizing, and then preparing a magnet composition. As a result, it is directly filled in the mold of the molding machine, compressed and molded,
It was used as a magnet after heat curing. Molding can be performed in a magnetic field, and by orienting the easy axis of magnetization of the magnetic powder in the magnetic field direction,
It is possible to manufacture a magnet having high magnetic characteristics. When a thermoplastic resin is used, a magnetic powder of an inorganic material and a thermoplastic resin of an organic material or a thermoplastic resin and an additive are mixed in a molten state, once solidified and then crushed, and molded as a magnet composition. It is charged into the heating and melting section of the machine and filled into the mold in the state of being heated and melted until sufficient fluidity is obtained again, cooled and solidified and then taken out and used as a magnet, or it is also fed into the mold in the state of being heated and melted. The magnet was passed through this mold and cooled to solidify. Similar to the case of the thermosetting resin, an anisotropic magnet is obtained by applying a magnetic field to the peripheral portion of the molding die using a magnetic circuit during molding and orienting the magnet composition while molding.

[0003]

However, the above-mentioned prior art has the following problems.

(1) In the case of a resin-bonded magnet using a thermosetting resin, a magnetic powder of an inorganic material and a thermosetting resin of an organic material or a thermosetting resin and an additive are directly mixed. For inorganic and organic materials, density, elastic modulus, coefficient of thermal expansion,
Since the surface energies and the like are greatly different, the adhesion at the interface is very poor, and the affinity between the magnetic powder and the thermosetting resin or the additive is weakened. Therefore, if such a magnet composition is used as a raw material for compression molding, only a molded product having a low strength can be obtained.
It also has low density and poor performance.

(2) In the case of a resin-bonded magnet using a thermoplastic resin, magnetic powder of an inorganic material and thermoplastic resin of an organic material or a thermoplastic resin and an additive are mixed in a molten state and once solidified. It is then crushed to obtain a magnet composition.
Similar to the above, even if mixed in the molten state, the inorganic material and the organic material have very different density, elastic modulus, thermal expansion coefficient, surface energy, etc., so the adhesiveness at the interface is very poor, and the magnetic powder and thermosetting resin or The affinity with additives becomes weak. For this reason, even if injection molding or extrusion molding is performed using such a magnet composition as a raw material, only a molded product having weak strength can be obtained. It also has low density and poor performance. Further, they are not uniformly mixed in a molten state, resulting in variations in density and performance, and deterioration in durability of melting equipment such as screws, cylinders and plungers.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a resin-bonded magnet having high strength, high density and high performance, and a method for manufacturing the same.

[0007]

A resin-bonded magnet and a method for producing the same according to the present invention comprises a resin-bonded magnet comprising magnetic powder and a thermosetting resin, or magnetic powder, a thermosetting resin and an additive. The resin-bonded magnet is characterized in that the magnetic powder is subjected to a coupling treatment.

A resin-bonded magnet made of magnetic powder and a thermoplastic resin, or a resin-bonded magnet made of magnetic powder, a thermoplastic resin and an additive is characterized in that the magnetic powder is subjected to a coupling treatment. To do.

[0009]

According to the present invention, by subjecting the magnetic powder to the coupling treatment, the affinity between the magnetic powder of the inorganic material and the thermosetting resin, the thermoplastic resin, the additive, etc. of the organic material is improved, and the magnetic property is improved. The strength, density, and performance of the resin-bonded magnet made of powder and thermosetting resin or the resin-bonded magnet made of magnetic powder, thermosetting resin, and additive are improved. Further, the strength, density, and performance are also improved in the resin-bonded magnet composed of magnetic powder and thermoplastic resin, or the resin-bonded magnet composed of magnetic powder, thermoplastic resin and additive.

[0010]

EXAMPLES The present invention will now be described in detail based on examples.

(Embodiment 1) A process chart of the present invention is shown in FIG. For the magnetic powder, for example, an Sm ₂ Co ₁₇ alloy is solution heat-treated and then an aging heat treatment is performed. This alloy is crushed with a crusher or the like, and further pulverized. The fine powder is subjected to a coupling treatment in order to improve the affinity with the thermosetting resin. The chemical formula of the coupling agent is H ₂ NCH ₂ CH ₂ CH ₂
Si (OCH ₂ CH ₃ ) ₃ → (RO) ₃ SiR ′, and RO is hydrolyzed to give a silanol group (Si—O).
H) is a triethoxy group (functional group), and R'is an amino group (organic functional group) that improves the affinity with the resin. The silane coupling agent forms a silanol group (Si-OH) in the presence of water and has a bond with the surface (-OH) of the magnetic powder. On the other hand, a group with a strong affinity for resin (R ')
To join.

As a result, the magnetic powder and the resin are crosslinked.
The coupling agent is diluted with ethyl alcohol, mixed with the magnetic powder, and the ethyl alcohol is volatilized. The solvent used here is not limited to ethyl alcohol, and any organic solvent such as methyl alcohol or methyl ethyl ketone may be used. Next, 110 ° C x 30
Curing process is performed in minutes. The thermosetting resin and, if necessary, an additive are weighed and mixed in the magnetic powder thus treated with the coupling treatment.

Examples of the thermosetting resin include ethylenically unsaturated polyester resin, epoxy resin and phenol resin. As additives, metallic soap (zinc stearate, sodium stearate, lithium stearate, calcium stearate, etc.), wax,
Lubricants such as higher fatty acids, peroxides, oleic acid and the like. After mixing, the mixture is kneaded with a sand mill or the like, granulated with a pelletizer, and sized with a shifter and a sieve. The magnet composition thus prepared is directly filled in a mold of a molding machine, taken out after compression molding, and cured. The characteristics when molded in a magnetic field are shown in Table 1 in comparison with the conventional example.

[0014]

[Table 1]

As described above, according to the present invention, the strength is dramatically improved, and the density and the performance are also improved.

(Embodiment 2) A process chart of the present invention is shown in FIG. For the magnetic powder, for example, an Sm ₂ Co _17- based alloy is subjected to solution heat treatment, followed by aging heat treatment. This alloy is crushed with a crusher or the like, and further pulverized. This fine powder is subjected to a coupling treatment in order to improve the affinity with the thermoplastic resin. The thermoplastic resin and, if necessary, additives are weighed and mixed in a desired mixing ratio. After mixing, the mixture is kneaded by heating it with a kneader such as a roll mill or an extruder to a temperature at which the thermoplastic resin melts or higher. Furthermore, it is crushed to a size that can be easily put into a molding machine to create a compound. Here, examples of the thermoplastic resin include plastics such as polyamide (PA) and polyphenylene sulfide (PPS), elastomers such as chlorinated polyethylene, synthetic rubber, and liquid crystal polymer. As additives, metal soaps (zinc stearate, sodium stearate, lithium stearate, calcium stearate, etc.), waxes, lubricants such as higher fatty acids, silicone oil, peroxides,
Oleic acid or the like was used. As the coupling agent, a titanate-based coupling agent, a silane-based coupling agent, or the like is effective. The magnet composition thus prepared is charged into the heating and melting section of the injection molding machine.

The magnet composition is heated and kneaded again in the cylinder portion of the molding machine to be in a molten state.

The molten magnet composition is cast by a screw into a mold cavity attached to a molding machine. The magnet composition in the cavity is uniformly cooled and solidified, and then taken out by a material removing device. The characteristics when molded in a magnetic field are shown in Table 2 in comparison with the conventional example.

[0019]

[Table 2]

As described above, according to the present invention, the strength is dramatically improved, and the density and the performance are also improved.

(Embodiment 3) A process diagram of the present invention is shown in FIG. The magnetic powder is, for example, Nd ₁₄ Fe ₈₁ B ₅ which is an isotropic magnet thin strip obtained by the quenching method into a bulk shape by hot pressing, and then anisotropic by a die upset method. The magnetized magnet is crushed with a crusher or the like, and further pulverized. The fine powder is subjected to a coupling treatment in order to improve the affinity with the thermosetting resin. The chemical formula of the coupling agent is H ₂ NCH ₂ CH ₂ CH ₂ S
i (OCH ₂ CH ₃ ) ₃ → (RO) ₃ SiR ′, and RO is hydrolyzed to produce a silanol group (Si—O).
H) is a triethoxy group (functional group), and R'is an amino group (organic functional group) that improves the compatibility with the resin.

The silane coupling agent forms a silanol group (Si-OH) in the presence of water, and the surface of the magnetic powder (-O
It has a bond with H). On the other hand, it is bound to the resin by a group (R ′) having a strong affinity. As a result, the magnetic powder and the resin are crosslinked. The coupling agent is diluted with ethyl alcohol, mixed with the magnetic powder, and the ethyl alcohol is volatilized. Next, curing treatment is performed at 110 ° C. for 30 minutes. The solvent used here is not limited to ethyl alcohol, and any organic solvent such as methyl alcohol or methyl ethyl ketone may be used. The thermosetting resin and, if necessary, an additive are weighed and mixed in the magnetic powder thus treated with the coupling treatment. Here, examples of the thermosetting resin include ethylenically unsaturated polyester resin, epoxy resin, and phenol resin. Examples of the additives include metallic soaps (zinc stearate, sodium stearate, lithium stearate, calcium stearate, etc.), waxes, lubricants such as higher fatty acids, peroxides, and oleic acid. After mixing, the mixture is kneaded with a sand mill or the like, granulated with a pelletizer, and sized with a shifter and a sieve. The magnet composition thus prepared is directly filled in a mold of a molding machine, taken out after compression molding, and cured. Table 3 shows the characteristics when molded in a non-magnetic field in comparison with the conventional example.

[0023]

[Table 3]

As described above, according to the present invention, the strength is dramatically improved, and the density and the performance are also improved.

(Embodiment 4) A process diagram of the present invention is shown in FIG. The magnetic powder is, for example, Nd ₁₄ Fe ₈₁ B ₅ which is an isotropic magnet thin strip obtained by the quenching method into a bulk shape by hot pressing, and then anisotropic by a die upset method. It is a crushed magnet. The magnetic powder thus obtained is subjected to a coupling treatment in order to improve the affinity with the thermoplastic resin. The thermoplastic resin and, if necessary, additives are weighed and mixed in a desired mixing ratio. After mixing, roll mill,
It is kneaded by heating it with a kneader such as an extruder to a temperature at which the thermoplastic resin is melted or higher. Furthermore, it is crushed to a size that can be easily put into a molding machine to create a compound. Here, examples of the thermoplastic resin include plastics such as polyamide (PA) and polyphenylene sulfide (PPS), elastomers such as chlorinated polyethylene, synthetic rubber, and liquid crystal polymer. As additives, metal soaps (zinc stearate, sodium stearate, lithium stearate, calcium stearate, etc.), waxes, lubricants such as higher fatty acids, silicone oil, peroxides,
Oleic acid or the like was used. As the coupling agent, a titanate-based coupling agent, a silane-based coupling agent, or the like is effective. The magnet composition thus prepared is charged into the heating and melting section of the injection molding machine. The magnet composition is heated and kneaded again in the cylinder portion of the molding machine to be in a molten state.
This molten magnet composition is cast by a screw into a mold cavity attached to a molding machine. The magnet composition in the cavity is uniformly cooled and solidified, and then taken out by a material removing device. Table 4 shows the characteristics when molded in a non-magnetic field in comparison with the conventional example.

[0026]

[Table 4]

As described above, according to the present invention, the strength is dramatically improved, and the density and the performance are also improved.

Although the present invention has been described with reference to the specific embodiments, it should not be construed that the present invention is limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, the magnetic powder may be ferrite powder. The coupling agent may be a silane coupling agent or a titanate coupling agent. Further, the coupling method was explained by the vapor method in which the coupling agent is once dissolved in an organic solvent and mixed with the magnetic powder, and then the solvent is volatilized, but the coupling agent is directly mixed with a thermosetting resin or a thermoplastic resin. Alternatively, a blending method of mixing with magnetic powder may be used.

[0029]

As described above, according to the resin-bonded magnet and the method for manufacturing the same of the present invention, a resin-bonded magnet having high strength, density and performance can be obtained.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a resin-bonded magnet of the present invention.

FIG. 2 is a manufacturing process diagram of the resin-bonded magnet of the present invention.

Claims (3)

[Claims] 1. A resin-bonded magnet comprising a magnetic powder and a thermosetting resin, or a resin-bonded magnet comprising a magnetic powder, a thermosetting resin and an additive, wherein the magnetic powder is subjected to a coupling treatment. A characteristic resin-bonded magnet. 2. A resin-bonded magnet composed of magnetic powder and a thermoplastic resin, or a resin-bonded magnet composed of magnetic powder, a thermoplastic resin and an additive, wherein the magnetic powder is subjected to a coupling treatment. Resin-bonded magnet that does. 3. The method for manufacturing the resin-bonded magnet according to claim 1.