JP2000232010A - Resin connected type magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin connected type magnet of which not only the magnetic characteristics but also flexibility of shape, formability, and mechanic strength are made superior. SOLUTION: This is a resin connected type magnet in which a composition constituted of magnetic powder and a resin binder is formed, and this resin binder is composed of at least, one kind of unsaturated polyester resin hardened body as main components. It is desirable that the resin binder contains peroxide, which can harden at 150 deg.C or lower of its reactant, and also that the anisotropic magnetic field of the magnetic powder is 50 kOe or higher, and the particles of the magnetic powder of 50 wt.% or more has a particle diameter which is 100 μm or smaller. The resin connected type magnet is molded by a light- emitting molding method, a light-emitting compression molding method, a light- emitting press molding method, or transfer molding method.

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 having excellent magnetic properties.

[0002]

2. Description of the Related Art In recent years, ferrite magnets, alnico magnets,
Rare earth magnets and the like are used for various applications including motors. However, since these magnets are mainly produced by a sintering method, they are generally brittle, and it is difficult to obtain thin magnets or complicated shapes. Further, since the shrinkage during sintering is as large as 15 to 20%, a product having high dimensional accuracy cannot be obtained, and there is a disadvantage that post-processing such as polishing is required to increase the accuracy.

A resin-bonded magnet solves these drawbacks and opens up new applications. It is made by filling a thermoplastic resin such as a polyamide resin or polyphenylene sulfide resin as a binder and filling it with magnetic powder. It is. However, a resin magnet using a thermoplastic resin as a binder is exposed to a high temperature of 200 ° C. or more during molding, and thus has a problem that the magnetic properties, particularly the coercive force, are deteriorated, and the shape of the squareness is inevitably reduced. A resin-bonded magnet in which the rate of decrease in the magnetic properties later was suppressed low could not be obtained.

Further, there has been proposed a thermosetting resin such as an epoxy resin or a bis-maleimide triazine resin as a binder, which is filled with magnetic powder. However, since the amount of the binder is scarce, simple molding by a compression molding method has been proposed. Only the product-bonded magnet was obtained. In recent years, resin-coupled magnets used in small motors, audio equipment, OA equipment, and the like are required to have excellent magnetic properties and have complicated shapes due to the demand for miniaturization of the equipment.

[0005] The relationship between the magnetic properties and the shape of the resin-bonded magnet obtained by the conventional method is insufficient for use in the above-mentioned applications, and early improvement of the resin-bonded magnet has been desired.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a resin-coupled magnet which has a low magnetic property but can be formed into a complicated shape, which is obtained by an injection molding method using a conventional thermoplastic resin. It has high magnetic properties obtained by compression molding using thermosetting resin, but eliminates the disadvantages of resin-bonded magnets with only a simple shape, especially due to the oxidative deterioration experienced during conventional high-temperature molding. Not only has excellent magnetic properties, but also has a high degree of freedom in shape, formability, and mechanical strength. It is an object of the present invention to provide a resin-bonded magnet which exhibits excellent rust-preventing effect and improves product yield.

[0007]

Means for Solving the Problems The present inventors have conducted various studies in order to achieve the above object, and as a result, obtained a composition of a magnetic powder and an unsaturated polyester resin by an injection molding method or a transfer molding method. By molding and manufacturing, it was found that a resin-bonded magnet having excellent magnetic properties, particularly shape coercivity, formability, and mechanical strength with excellent coercive force and orientation degree was obtained, and completed the present invention. .

That is, the resin-bonded magnet of the present invention is a resin-bonded magnet formed by molding a composition comprising a magnetic powder and a resin binder, wherein the resin binder comprises at least one hardened unsaturated polyester resin. It is characterized by the following. The resin binder containing the cured unsaturated polyester resin as a main component contains a peroxide curable at a temperature of 150 ° C. or lower or a reactant thereof, and the anisotropic magnetic field (HA) of the magnetic powder is 50 kOe or more, and 50% by weight or more of the magnetic powder particles have a particle size of 1
It is preferably not more than 00 μm.

The resin-bonded magnet according to the present invention can be obtained by injection molding, injection compression molding, injection press molding or transfer molding. The resin-bonded magnet of the present invention may have its surface covered with a thermosetting resin. Any of the above-mentioned resin-bonded magnets may be pulverized again and re-mixed with a thermosetting resin or a thermoplastic resin to form a resin-bonded magnet.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As the magnetic powder used in the present invention, a magnetic powder conventionally used for a resin-bonded magnet can be used. For example, a rare-earth-cobalt-based or rare-earth-iron magnetic powder having an anisotropic magnetic field (HA) of 50 kOe or more is used. Magnetic powders such as boron-based and rare earth-iron-nitrogen based.

The present inventors have found that in the above resin-bonded magnet, the Sm-
Sm obtained by nitriding and finely pulverizing Fe-based alloy coarse powder
-Fe-N based alloy powder, also fine alloy powder was Sm-Co ₅ alloy coarse powder was finely pulverized, obtained by reduction and diffusion method, obtained by Nd-Fe-B based liquid quenching method Alloy powder, HDDR (Hydrogenatio
n-Disproportionation-Deso
It has been confirmed that a resin-bonded magnet having particularly excellent magnetic properties can be obtained by using an anisotropic Nd—Fe—B-based alloy powder obtained by the rption-recombination method. The Nd-Fe-B-based magnetic powder obtained by the liquid quenching method and the anisotropic Nd-Fe-B-based magnetic powder obtained by the HDDR method contain a large amount of relatively large particles having a peculiar shape. Therefore, it is preferable to use the powder after being pulverized by a jet mill or a ball mill. The present invention can exert a remarkable effect in a composition containing 50% by weight or more of those magnetic powders having a particle size of 100 μm or less, and an anisotropic magnetic powder which requires molding in a magnetic field rather than isotropicity. Is more remarkable in terms of alignment characteristics.

Next, the unsaturated polyester resin, which is an essential component in the present invention, cures in a mold during molding and functions as a binder for magnetic powder. Commercially available unsaturated polyester resins can be used, or two or more unsaturated polyester resins can be used in combination. As the unsaturated polyester resin, for example, a main agent obtained by preliminarily polymerizing an unsaturated polybasic acid and / or a saturated polybasic acid and a glycol to a molecular weight of about 5,000 or less to form an oligomer or a prepolymer also serves as a crosslinking agent. It is composed of monomers, a curing agent for initiating the reaction, a polymerization inhibitor for ensuring long-term storage stability, and other additives.

The unsaturated polybasic acids include, for example, maleic anhydride, fumaric acid, itaconic acid and the like. The saturated polybasic acids include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, methyltetrahydroanhydride. Examples thereof include phthalic acid, endomethylenetetrahydrophthalic anhydride, adipic acid, sebacic acid, hetic acid, and tetrabromophthalic anhydride. Examples of the glycols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,6-hexanediol, hydrogenated bisphenol A, bisphenol A propylene oxide adduct, Muneopentyl glycol, pentaerythritol diallyl ether, allyl glycidyl ether and the like.

Examples of the monomer which also serves as a crosslinking agent include vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, methyl methacrylate, and vinyl acetate; diallyl phthalate, diallyl isophthalate, triallyl isophthalate, triallyl isocyanate. Examples include allyl monomers such as nurate and diallyltetrabromophthalate, and acrylates such as phenoxyethyl acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, and 2-hydroxyethyl acrylate.

As the curing agent, a peroxide curable at a temperature of 150 ° C. or less or a reactant thereof is used. Generally, an organic peroxide is used, such as methyl ethyl ketone peroxide, cyclohexanone peroxide, or the like.
Ketone peroxides such as 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, and acetylcetone peroxide;
Trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-bis (t-butylperoxy) valerate, Peroxy ketals such as 2,2-bis (t-butylperoxy) butane, t-butyl hydroperoxyside, cumene hydroperoxyside, di-isopropylbenzene hydroperoxide, menthane hydroperoxide, 2,5- Hydroperoxides such as dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, di- Cumyl peroxide, α, α '
-Bis (t-butylperoxy-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-
Dialkyl peroxides such as butylperoxy) hexine-3, acetyl peroxide, isobutyl peroxide, octanyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,
Diacyl peroxides such as 5,5-trimethylhexanoyl peroxide, succinic acid peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and toluoyl peroxide; di-isopropylperoxydicarbonate;
2-ethylhexylperoxydicarbonate, di-n-
Propylperoxydicarbonate, bis- (4-t-butylcyclohexyl) peroxydicarbonate, di-myristylperoxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di-methoxyisopropylperoxydicarbonate, di- Peroxydicarbonates such as (3-methyl-3-methoxybutyl) peroxydicarbonate and diallylperoxydicarbonate;
t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-butylperoxyneodecanoate, cumylperoxyneodecanoate, t-butylperoxy-2-ethylhexa Noate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-
Butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, kumi Luperoxy octoate, t-hexyl peroxy neodecanoate, t-hexyl peroxy pivalate, t-butyl peroxy neo hexanoate, t-hexyl peroxy neo hexanoate, cumyl peroxy neo hexanoate Peroxyesters, acetylcyclohexylsulfonylperoxide, t-butylperoxyallyl carbonate, and the like.

The reason why a peroxide curable at a temperature of 150 ° C. or less or a reactant thereof is used as a curing agent in the present invention is that a material curable at a temperature exceeding 150 ° C. has poor magnetic properties, especially coercive force. This is because it is greatly reduced. Some of the above-mentioned organic peroxides can be used alone, but depending on the type, they can be used in a state of being diluted in a hydrocarbon solution or phthalate, or in a state of being absorbed in a solid powder. . Anyway 15
The type is not particularly limited as long as a peroxide curable at a temperature of 0 ° C. or less or a reactant thereof is used as a curing agent, but the decomposition temperature for obtaining a half-life of 10 hours is 120 ° C.
It is desirable to use an organic peroxide having the following properties, and more preferably an organic peroxide having a decomposition temperature of 40 ° C. or more and 100 ° C. or less for obtaining the same half-life. If the half-life is more than 120 ° C., the curing temperature for obtaining a sufficiently cured molded body is increased and the curing time is prolonged, so that the effect of preventing the magnetic properties of the present invention from lowering is reduced. If the temperature is lower than ° C, not only the handling of the peroxide itself becomes difficult, but also the storage properties of the resin-bound magnet pre-molding composition of the present invention become poor, resulting in a lack of productivity. However, it is needless to say that even an organic peroxide having a preferable half-life decomposing time can be used in the present invention if conditions in the molding method are adjusted.

The amount of the peroxide to be added cannot be specified because it varies depending on the dilution ratio and the amount of active oxygen, but generally, it is 0.01 to 5% by weight based on the unsaturated polyester resin.
Is added. These peroxides can be used alone or in a mixture of two or more. For example, cobalt organic acid salts such as cobalt naphthenate and cobalt octylate, and β-diketones such as acetylacetone, ethyl acetoacetate, and dimedone. , Dimethylaniline and other aromatic tertiary amines, mercaptans, phosphorus compounds such as triphenylphosphine, 2-ethylhexyl phosphite, accelerators such as quaternary ammonium salts, and azo compounds such as azobisisobutyronitrile , An aromatic carbonyl compound, a pinacon derivative and the like.

Examples of the polymerization inhibitor for ensuring long-term storage stability include p-benzoquinone, naphthoquinone, phenanthraquinone, tolquinone, 2,5-diphenyl-p-benzoquinone, and 2,5-diacetoxy-p. −
Quinones such as benzoquinone, 2,5-dicaproxy-p-benzoquinone, 2,5-diasiloxy-p-benzoquinone, hydroquinone, pt-butylcatechol;
2,5-di-t-butylhydroquinone, mono-di-t
-Butylhydroquinone, hydroquinones such as 2,5-di-t-amylhydroquinone, di-t-butyl.
Paracresol hydroquinone monomethyl ether, phenols such as alpha naphthol, organic and inorganic copper salts such as copper naphthenate, acetamidine acetate, amidines such as acetamidine sulfate,
Hydrazines such as phenylhydrazine hydrochloride and hydrazine hydrochloride, trimethylbenzylammonium chloride, laurylpyridinium chloride, cetyltrimethylammonium chloride, phenyltrimethylammonium chloride, trimethylbenzylammonium oxalate, di (trimethylbenzylammonium) oxalate, trimethylbenzylammonium Maleates, trimethylbenzylammonium tartrate, quaternary ammonium salts such as trimethylbenzylammonium glycolate, phenyl-β-naphthylamine,
Amines such as parabenzylaminophenol, di-β-naphthylparaphenylenediamine, nitrobenzene,
Nitro compounds such as trinitrotoluene and picric acid,
Oximes such as quinone dioxime and cyclohexanone oxime; polyhydric phenols such as pyrogallol, tannic acid and resorcin; amine hydrochlorides such as triethylamine hydrochloride, dimethylaniline hydrochloride, and dibutylamine hydrochloride; Species or a mixture of two or more can be used.

The one or more unsaturated polyester resin binders used in the present invention can be molded into a resin-bonded magnet by adding various additives in addition to these various components. For example, novolak or bisphenol type vinyl ester resins using epoxy resin as a raw material, phenol resin, urea resin, melamine resin, diallyl phthalate resin, epoxy resin, silicone resin, urethane resin, polyimide resin, bis maleimide triazine resin, polyamide Reactive resins such as imide resins, and for the purpose of improving moldability, for example, paraffin wax,
Waxes such as liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, microwax, fatty acids such as stearic acid, 1,2-oxystearic acid, lauric acid, palmitic acid, oleic acid, calcium stearate, stearic acid Fatty acid salts (metal soaps) such as barium, magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate, zinc 2-ethylhexoate, stearic acid amide, oleic acid Amide, erucamide, behenamide, palmitic amide, lauric amide, hydroxystearic amide, methylenebisstearic amide, ethylenebisstearyl Acid amide, ethylenebis lauric acid amide, distearyl adipic acid amide, ethylenebis oleic acid amide, dioleyl adipic acid amide, N-
Fatty acid amides such as stearyl stearic acid amide, fatty acid esters such as butyl stearate, alcohols such as ethylene glycol and stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and polyethers composed of modified products thereof, dimethylpolysiloxane , Polysiloxanes such as silicon grease, fluorine compounds such as fluorine-based oil, fluorine-based grease, and fluorine-containing resin powder; and inorganic compound powders such as silicon nitride, silicon carbide, magnesium oxide, alumina, silicon dioxide, and molybdenum disulfide. Seeds or two or more kinds can be added.

In addition to these organic additives, if necessary,
Inorganic fillers and pigments may be optionally added. Examples of the inorganic filler include ferrite magnetic powders such as strontium ferrite and barium ferrite, soft magnetic powders such as iron, high specific gravity metal powders for density adjustment such as tungsten, flame retardants such as antimony trioxide, and titanium oxide. And the like.

Each component to be mixed with the unsaturated polyester resin binder is not limited by the degree of polymerization or molecular weight, but is measured by a rotational viscosity measurement method at a molding temperature in a mixing adjustment state before adding a magnetic powder. Dynamic viscosity is 100m
It is preferable to be included in the range of Pa · s to 5000 mPa · s. In order to adjust to this viscosity, mix several types of clay and unsaturated polyester resins with different properties,
Oxides and hydroxides of divalent metals such as beryllium oxide and magnesium oxide, diisocyanates, alidiline compounds, and aluminum isopropoxide may be added. Therefore, the properties of each component constituting the unsaturated polyester resin binder are, for example, liquid at room temperature, powder, beads, pellets and the like are not particularly limited, but become liquid after mixing from the viewpoint of uniform mixing with the magnetic powder and moldability. Is desirable. Further, these resins and those having different molecular weights and properties may be mixed alone or in combination of two or more.

The viscosity of the final mixed binder mainly composed of these thermosetting resins is measured according to JIS K7117 (viscosity test method for liquid resin using a rotational viscometer). The temperature is measured in a thermostatic bath according to the temperature of the cylinder. The measured value at that time is 10
It is desirable to use a material having a pressure of 0 mPa · s to 5000 mPa · s.
Pa · s is more preferable. This dynamic viscosity is 100
If the pressure is less than mPa · s, the magnetic powder and the binder may be separated from each other during the injection molding, so that molding cannot be performed.
If it exceeds 0 mPa · s, the kneading torque will increase significantly and the fluidity will decrease, making molding difficult, so that the effects of the present invention cannot be obtained.

The amount of addition of these unsaturated polyester resin binders is more than 5 parts by weight and less than 50 parts by weight with respect to 100 parts by weight of the magnetic powder, including the respective components. , Preferably at least 7 parts by weight
It is more preferably 5 parts by weight or less, more preferably 10 parts by weight or more and 13 parts by weight or less. When the amount of the resin binder compound is 5 parts by weight or less based on 100 parts by weight of the magnetic powder,
The effect of the present invention cannot be obtained due to a significant decrease in the strength of the molded body and a decrease in fluidity during molding. If the amount is more than 50 parts by weight, desired magnetic properties cannot be obtained.

In the present invention, the mixing method of each component is not particularly limited. For example, a mixing machine such as a ribbon blender, a tumbler, a Nauta mixer, a Henschel mixer, a super mixer, or a Banbury mixer, a kneader, a roll, a kneader ruder, It is carried out using a kneader such as a screw extruder or a twin screw extruder. The composition before molding of the resin-bonded magnet of the present invention is obtained in a lump by mixing the respective components. The obtained composition is molded by a molding machine for various thermosetting resins such as an injection molding machine or a transfer molding machine, particularly preferably by an injection molding machine, and a molding machine having an additional function of injection compression molding or injection press. May be molded.

As described above, in the present invention, a resin-bound magnet is obtained by molding and curing a composition comprising a magnetic powder and a resin binder containing at least one unsaturated polyester resin as a main component. Can be. Further, in the present invention, in order to exhibit the rust-preventive effect of the obtained resin-bonded magnet, the surface of the resin-bonded magnet is epoxy resin,
It can be coated with a thermosetting resin such as bis-maleimide triazine resin. At this time, the thickness of the film to be coated is 10 to 100 from the viewpoint of maintaining the magnetic properties and the rust prevention effect.
It is preferably set to μm.

Further, in the present invention, except for the case where the thermosetting resin is coated on the surface, the resin-bonded magnet obtained as described above, in particular, a half-end portion or an extra After grinding the parts again to 200 μm or less,
Since it is possible to obtain a resin-bonded magnet by remixing with a thermosetting resin as exemplified above or a thermoplastic resin such as a polyamide resin or polyphenylene sulfide resin similar to the conventional one and molding in the same manner as above. ,
Product yield can also be greatly improved. The addition amount of the thermosetting resin or thermoplastic resin to the resin-bonded magnet pulverized material is 10 to 10 parts by weight of the pulverized material.
It is preferred to be in the range of 100 parts by weight.

[0027]

The present invention will be more specifically described below with reference to examples and comparative examples. The details of each component used in the examples and comparative examples, test methods, and evaluations are exemplified, but the present invention is not limited thereto without departing from the gist of the present invention. A resin-bonded magnet was manufactured and evaluated using the following materials and methods. The materials used are shown below.

A Magnetic powder Magnetic powder 1: Sm-Fe-N based magnetic powder (Sm-Fe-N alloy powder manufactured by Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 210 kOe, particle size 100 μm or less
Magnetic powder 2: Sm-Co based magnetic powder (trade name: RCo ₅ alloy, manufactured by Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 246 kOe, particle size 100 μm or less: 99
Magnetic powder 3: Nd-Fe-B-based magnetic powder (trade name: MQP-B, manufactured by Magnequench International Co., Ltd.) Anisotropic magnetic field: 70 kOe, 62% by weight containing a particle size of 100 μm or less. Magnetic powder 4: Nd-Fe-B-based magnetic powder (trade name: MQP-B, manufactured by Magnequench International Co., Ltd.) Anisotropic magnetic field: 70 kOe, containing 31% by weight of particle diameter of 100 μm or less

B Thermosetting Resin and Nylon 12 as Comparative Example Unsaturated Polyester Resin (UP Resin 1) (trade name: Epolac N-21B, manufactured by Nippon Shokubai Co., Ltd.) Viscosity at 25 ° C. 110 mPa · s Saturated polyester resin (UP resin 2) (trade name: Rigolac 4214, manufactured by Showa Polymer Co., Ltd.) Viscosity at 25 ° C. 3,800 mPa · s ・ Unsaturated polyester resin (UP resin 3) (trade name: Rigolac M-500D, Showa) Polymer Co., Ltd.
Viscosity at 25 ° C. 1100 mPa · s Nylon 12 (trade name: DAIAMID A-1709P, manufactured by Daicel Huls Co., Ltd.)

C Curing agent Curing agent 1: Peroxyester peroxide (t-butylperoxybenzoate) (trade name: Perbutyl Z,
Decomposition temperature for obtaining a half-life of 10 hours 104 ° C Curing agent 2: Hydroperoxide-based peroxide (p-
(Mentane hydroperoxide) (trade name: Permenta H, manufactured by NOF Corporation) Decomposition temperature of 133 ° C. for obtaining a half-life of 10 hours Curing agent 3: Hydroperoxide peroxide (cumene hydroperoxide) (Trade name: Park Mill H, manufactured by NOF Corporation) Decomposition temperature of 158 ° C to obtain a half-life of 10 hours

Next, the production method and evaluation method of each molded article were carried out as follows. 1. Adjustment of viscosity of resin binder The viscosity of each unsaturated polyester resin was adjusted by the following method. "UP Resin 1" was prepared using an evaporator.
Styrene was volatilized and reduced in a warm bath at 0 ° C. under reduced pressure to increase the viscosity to 700 mPa · s to obtain “UP resin 1 ′”.
“UP resin 2” was obtained by appropriately mixing styrene with the obtained resin and reducing the viscosity at 25 ° C. to 2500 mPa · s to obtain “UP resin 2 ′”.

2. Mixing and Preparation of Composition To a total amount of each magnetic powder, a predetermined thermosetting resin, a curing agent, and the like are added in a predetermined ratio (each part by weight). 0.5 parts by weight of calcium stearate was added, and the mixture was thoroughly mixed and stirred in a planetary mixer with a water-cooled jacket (40 rpm).
m, 30 ° C.) to obtain a composition before molding of the resin-bonded magnet. In Comparative Examples 3 and 4 in which nylon 12 was used as the resin among the compositions obtained from these, 20 m
mφ single extruder (L / D = 25, CR = 2.0, rotation speed = 20 rpm, 5 mmφ strand die, cylinder temperature 200 to 220 ° C., die temperature 100 to 150 ° C.
° C) and φ5 with a hot cut pelletizer
A resin-bonded magnet molding pellet compound of mm × 5 mm was prepared.

3. Injection molding method These compositions or compounds are molded with an injection molding machine equipped with an in-line screw type or plunger type magnetic field generator into a resin-bonded magnet for cylindrical test of φ10 mm × 15 mm at a molding temperature (cylinder temperature) of 30 to 180 ° C. Molding was performed under the conditions of a mold temperature (curing temperature) of 100 to 220 ° C., and the obtained magnet molded products were evaluated by the methods described below. In addition, Sm-Co system (magnetic powder 2) and Sm-
Only when magnetic powder of Fe-N system (magnetic powder 1) is used.
Molding was performed in a mold in a magnetic field of ２０20 kOe.

4. Each Evaluation Method 4-1 Evaluation of Magnetic Properties The magnetic properties of the resin-bonded magnet sample obtained under the above-described injection molding conditions were measured at room temperature with a thiophy-type magnetic fluxmeter. Tables 2 to 4 show the results of the coercive force, magnetization, squareness, maximum magnetic energy product, and degree of orientation among the magnetic characteristics. The degree of orientation is determined by the SMM method, that is, Δ (magnetization of resin-bonded magnet after molding) / (magnetization measured by VSM with 100% magnetic powder × volume ratio of magnetic powder of resin-bonded magnet after molding) × 100 Indicated by｝. The limit values in the conventional method are as shown in Table 1 below.

[0035]

[Table 1]

Therefore, if the value is equal to or more than the limit value shown in Table 1, it can be determined that "effective". 4-2 Mechanical strength Width 5 mm x height 2 mm x length 10 separately under the above molding conditions
JIS K as a mechanical strength
The shear punching strength was measured according to 7214 (shear test method by punching plastic). The results are shown in Tables 2 to 4 below.

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

As can be seen from Tables 2 to 4, the resin-bonded magnets of Examples 1 to 10 all have the coercive force, magnetization, squareness, maximum energy product, and orientation degree which are equal to or greater than the limit values in Table 1. Although the mechanical strength also showed an extremely high value of 64 MPa or more, Comparative Example 1 did not result in molding, and Comparative Example 2
In Comparative Examples 3 and 4, one of the magnetic properties was lower than the limit value, although the magnetic properties were almost in the vicinity of the limit value, but there was a problem as a product due to the occurrence of voids.

Next, a film of about 50 μm of an epoxy resin was formed on the surface of the resin-bonded magnet obtained in Example 1 above. On the other hand, one prepared without forming any film on the surface of the resin-bonded magnet obtained in Example 1 was prepared, and these two samples were left in a constant temperature bath at a temperature of 60 ° C. and a humidity of 95% for 100 hours to remove rust. The occurrence situation was observed, and the results are shown in Table 5 below.

[0042]

[Table 5]

As can be seen from Table 5, Example 11 in which the surface of the resin-bonded magnet was coated with the epoxy resin had a much longer rust generation time than Comparative Example 5 which had no coating, and had a sufficient rust prevention effect. Was.

Next, a description will be given of a resin-bonded magnet prepared by reusing the resin-bonded magnets according to Example 1 and Comparative Example 3. First, the resin-bonded magnets according to Example 1 and Comparative Example 3 were crushed by a plastic crusher,
The particles were sieved to a maximum particle size of 100 μm or less, and a resin-bonded magnet was prepared by the method described in 1 to 3 above, and the performance was evaluated by the method described in 4 above. Table 6 shows the results.

[0045]

[Table 6]

As can be seen from Table 6, the resin-bonded magnets obtained in Examples 12 and 13 exhibited superior magnetic properties as compared with those obtained in Comparative Examples 6 and 7.

[0047]

As described above, according to the present invention, a composition comprising a magnetic powder and an unsaturated polyester resin is produced by an injection molding method or the like, whereby the magnetic properties, the degree of freedom in shape, and the like are improved.
It is possible to provide resin-bonded magnets that are excellent in mechanical strength, etc., can further exhibit rust prevention effect, and improve product yield, for example, general home appliances, communications,
It is particularly useful in a wide range of fields, such as audio equipment, medical equipment, and general industrial equipment.

Claims (10)

[Claims] 1. A resin-bonded magnet formed by molding a composition comprising a magnetic powder and a resin binder, wherein the resin binder comprises at least one cured product of an unsaturated polyester resin as a main component. Resin-bonded magnet. 2. The resin binder containing a cured unsaturated polyester resin as a main component, which contains a peroxide curable at a temperature of 150 ° C. or lower or a reactant thereof. The resin-bonded magnet as described in the above. 3. An anisotropic magnetic field (HA) of the magnetic powder is 5
3. The method according to claim 1, wherein the pressure is 0 kOe or more.
The resin-bonded magnet as described in the above. 4. The method according to claim 1, wherein 50% by weight or more of the particles of the magnetic powder have a particle size of 100 μm or less.
4. The resin-bonded magnet according to any one of 3. 5. The composition has a viscosity at a molding temperature of 100 mPa · s to 5000 m as measured by a rotational viscometer.
The resin-bonded magnet according to any one of claims 1 to 4, wherein the magnet is in a range of Pa · s. 6. The method according to claim 1, wherein the amount of the unsaturated polyester resin added is more than 5 parts by weight and less than 50 parts by weight based on 100 parts by weight of the magnetic powder. Resin-bonded magnet. 7. The resin bond according to claim 1, wherein the peroxide is an organic peroxide having a decomposition temperature of 120 ° C. or less for obtaining a half life of 10 hours. Type magnet. 8. The molding of the composition comprising the magnetic powder and the resin binder is performed by an injection molding method, an injection compression molding method, an injection press molding method or a transfer molding method. The resin-bonded magnet according to claim 1. 9. The resin-bonded magnet according to claim 1, wherein the surface is further coated with a thermosetting resin. 10. A resin-bonded magnet, wherein the resin-bonded magnet according to claim 1 is crushed again and remixed with a thermosetting resin or a thermoplastic resin.