JPH0917619A - Composition for resin bond type magnet and resin bond type magnet - Google Patents

Abstract

PURPOSE: To provide a resin bond type magnet which enables the high filling-up of magnetic powder and has excellent magnetic characteristics, moldability, and physical characteristics (especially, mechanical strength). CONSTITUTION: In composition composed of magnetic powder wherein the anisotropic magnetic field (HA) is at least 50kOe, and one or two or more kinds of polyamide resin, polyethylene-ethyl acrylate copolymer resin of 0.01-30 pts.wt. and modified silicone oil of 0.01-10 pts.wt. are added to polyamide resin of 100 pts.wt. As to the silicone oil, at least one out of end groups and/or side chains in a molecule has epoxy group and/or glycidyl ether group and/or amino group and/or carboxyl group. By heating and molding the composition, this resin bond type magnet is obtained.

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 composition, and more particularly to a composition which gives a resin-bonded magnet excellent in magnetic properties, moldability and physical properties (in particular, mechanical strength). .

[0002]

2. Description of the Related Art In recent years, ferrite magnets, alnico magnets,
Rare earth magnets are used in various applications such as motors. However, since these magnets are mainly produced by a sintering method, they are generally fragile, and it is difficult to obtain thin magnets and complicated magnets. Further, since the shrinkage at the time of sintering is as large as 15 to 20%, it is not possible to obtain a product with high dimensional accuracy, and there is a drawback that post-processing such as polishing is required to improve accuracy.

The resin-bonded magnet solves these drawbacks and opens up new applications. It uses a thermoplastic resin such as nylon as a binder and is filled with magnetic powder. However, in a resin magnet using a thermoplastic resin as a binder, when the magnetic powder is filled in an amount of 80 wt% or more, the viscosity at the time of melt molding increases rapidly and molding becomes difficult. Mechanical strength is unavoidable because molding is performed by adding lubricants for thermoplastic resins such as acid metal soaps and paraffins. Therefore, not only the expected magnetic properties were not obtained despite the filling with the magnetic powder, but also a resin-bonded magnet molded product satisfying all the moldability and mechanical strength could not be obtained.

[0004]

In recent years, small motors,
Resin-bonded magnets used for audio equipment, OA equipment, etc.
Due to the demand for miniaturization of equipment, it is required to have high magnetic properties as well as excellent moldability and physical properties (mechanical strength, etc.), but conventional magnetic powder, polyamide resin and lubricant These characteristics of resin-bonded magnets are
This is insufficient for use in the above applications, and early improvement of resin-bonded magnets has been desired.

Therefore, an object of the present invention is to solve the drawbacks of conventional polyamide resin-bonded magnets and to provide resin-bonded magnets excellent in magnetic characteristics, moldability and physical characteristics (in particular, mechanical strength). It is to provide the composition for magnets to give.

[0006]

[Means for Solving the Problems] The inventors of the present invention conducted various investigations by changing the kind and amount of the additive in order to achieve the above object, and as a result, based on 100 parts by weight of the polyamide resin, Polyethylene-ethyl acrylate copolymer resin in a proportion of 0.01 to 30 parts by weight, and at least one of the terminal groups and / or side chains in one molecule is an epoxy group and / or.
Alternatively, by adding a modified silicone oil having a glycidyl ether group and / or an amino group and / or a carboxyl group in an amount of 0.01 to 10 parts by weight, excellent magnetic properties, molding processability, and physical properties (especially mechanical properties) It was found that a resin-bonded magnet having a desired strength) was obtained, and the present invention was completed.

That is, according to the present invention, the anisotropic magnetic field (H _A ) is 5
In a composition comprising 0 kOe or more of magnetic powder and one or more polyamide resins, the proportion of the polyethylene-ethyl acrylate copolymer resin is 0.01 to 30 parts by weight with respect to 100 parts by weight of the polyamide resin. And at least one of the terminal groups and / or side chains in one molecule is an epoxy group and / or a glycidyl ether group and / or
Alternatively, a modified silicone oil having an amino group and / or a carboxyl group is added in an amount of 0.01 to 10 parts by weight, and a resin-bonded magnet composition, and the resin-bonded magnet composition. Excellent magnetic properties, molding processability, and physical properties by heat molding (especially,
It was found that a resin-bonded magnet having mechanical strength) can be obtained.

[0008]

Hereinafter, the present invention will be described in detail. The magnetic powder used in the present invention has an anisotropic magnetic field (H _A ) of 50 kO.
Magnetic powders that are generally used in resin-bonded magnets can be used as long as they are magnetic powders of e or more, and examples thereof include rare earth cobalt-based, rare earth-iron-boron-based, and rare earth-iron-nitrogen-based magnetic powders. To be

In the resin-bonded magnet composition described above, the inventors of the present invention use the above-exemplified alloy powder of the Sm-Co ₅ system by the reduction diffusion method or Sm-Fe-N system alloy powder as the magnetic powder. It has been confirmed that a resin-bonded magnet having a particularly high magnetic property such as 93 wt% or more can be obtained. The Sm-Co5 magnetic powder obtained by the reduction diffusion method is preferably pulverized by a jet mill, a ball mill or the like. The preferred particle size of these magnetic powders is 7 μm or less on average, and particularly preferably 5 μm or less on average.

Further, in the composition, the polyamide resin which is an essential component functions as a binder for the magnetic powder, and the polyamide resin used in the present invention is not particularly limited, and examples thereof include 6 nylon and 6 nylon. , 6 nylon, 11 nylon, 12 nylon, 6,12 nylon, aromatic nylon, etc., and their homopolymers, copolymers with other kinds of monomers, and end group-treated products with other substances, etc. Can be mentioned. In addition, 2 of these polyamide resins
Systems in blends of more than one type are naturally included. The melt viscosity and molecular weight of these polyamide resins are preferably as low as possible in the range where the desired mechanical strength can be obtained, and the shape is not particularly limited, such as powder, beads, and pellets, but in view of uniform mixing with magnetic powder, it is powder. Is desirable.

On the other hand, when the magnetic powder is filled in an amount of more than 95% by weight, the kneading torque and the fluidity are remarkably lowered and the molding becomes difficult, and when it is less than 80% by weight, desired magnetic properties cannot be obtained. . Therefore, the filling amount of magnetic powder is 80
It is preferably in the range of not less than 95% by weight and not more than 95% by weight.

[0012] The magnetic powder may be optionally replaced with a silane-based material.
A titanium-based or aluminum-based surface treating agent, that is, a coupling agent or the like can be used in the range of 0.1 to 3.0% by weight based on the magnetic powder. Examples of these coupling agents include silane-based vinyltriethoxysilane and γ.
-Aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane,
N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, etc. Also, titanium-based isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N- Aminoethyl-aminoethyl) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate, etc. A typical rate is a rate.

Next, the resin-bonded magnet composition of the present invention is a polyethylene-ethyl acrylate copolymer resin in addition to the above-mentioned magnetic powder and polyamide resin, without being restricted by the degree of polymerization or the molecular weight. One kind or two or more kinds may be added to the composition for use, but it is preferable to use one having a molecular weight of 10,000 or more. The shape can be used in the form of powder or pellets,
Considering the mixing and dispersibility, powdery materials are preferable.

These compounds correspond to the polyamide resin 10
It is added in a proportion of 0.01 part by weight or more and 30 parts by weight or less, preferably 0.1 part by weight or more and 15 parts by weight or less, and more preferably 1 part by weight or more and 7 parts by weight or less, relative to 0 part by weight. The compound may be mixed simultaneously with the magnetic powder and the polyamide resin. The amount of the compound added is the polyamide resin 1
If the amount is 0.01 parts by weight or less with respect to 00 parts by weight, the moldability deteriorates, and as a result, the content of magnetic powder cannot be increased, so that a magnet having high magnetic properties cannot be obtained. If the amount added is 30 parts by weight or more, desired physical properties (especially mechanical strength) cannot be obtained.

Next, in the resin-bonded magnet composition of the present invention, in addition to the above-mentioned magnetic powder and polyamide resin, at least one of terminal groups and / or side chains in one molecule is an epoxy group and / or glycidyl. It is characterized in that a modified silicone oil having an ether group and / or an amino group and / or a carboxyl group is added. These compounds are, for example, terminal glycidyl-modified silicone oil, side chain glycidyl-modified silicone oil, terminal alicyclic epoxy group-modified silicone oil, side chain alicyclic epoxy group-modified silicone oil, epoxy polyether modified silicone oil, terminal amino-modified silicone oil. , Side chain amino modified silicone oil, terminal carboxy modified silicone oil, side chain carboxy modified silicone oil, etc., and the silicone oil portion is dimethyl type, diethyl type, methyl ethyl type, methyl phenyl type. , Ethylphenyl type, diphenyl type, methylhydrogen type, ethylhydrogen type, phenylhydrogen type, dihydrogen type and the like, and these complex types can of course be used. They are,
The composition may be added alone or in combination of two or more without being restricted by the degree of polymerization or the molecular weight.

These compounds correspond to the polyamide resin 10
It is added in a proportion of 0.01 part by weight or more and 10 parts by weight or less, preferably 0.1 part by weight or more and 5 parts by weight or less, more preferably 1 part by weight or more and 3 parts by weight or less, relative to 0 part by weight. The compound may be mixed with the magnetic powder and the polyamide resin at the same time, or may be directly added to the polyamide resin in advance to cause various reactions and then mixed with the magnetic powder. The amount of the compound added is 0.0 with respect to 100 parts by weight of the polyamide resin.
When the amount is 1 part by weight or less, the molding processability is deteriorated, and as a result, the content of the magnetic powder cannot be increased, so that a magnet having high magnetic properties cannot be obtained. Further, if the addition amount is 10 parts by weight or more, desired physical properties (especially mechanical strength) cannot be obtained.

In addition to the above-mentioned components, the composition of the present invention may contain a plastic molding lubricant, various stabilizers and the like.

Examples of the lubricant include waxes such as paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, and microwax, stearic acid, 1,2-
Fatty acids such as oxystearic acid, lauric acid, palmitic acid, oleic acid, calcium stearate, barium stearate, magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate , Fatty acid salts (metal soaps) such as zinc 2-ethylhexoate, stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, lauric acid amide, hydroxystearic acid amide, methylenebisstearic acid amide, Ethylenebisstearic acid amide, ethylenebislauric amide, distearyladipamide, ethylenebisoleic amide, dioleyladipamide, N-stearylstearin Amides such as fatty acid amides, fatty acid esters, ethylene glycol and butyl stearate,
Alcohols such as stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethers composed of these modified products, dimethylpolysiloxane, polysiloxanes such as silicon grease, fluorine-based oil, fluorine-based grease,
Examples include fluorine compound such as fluorine-containing resin powder, and inorganic compound powder such as silicon nitride, silicon carbide, magnesium oxide, alumina, silicon dioxide, and molybdenum disulfide.

As the stabilizer, bis (2,2,
6,6, -Tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6, -pentamethyl-4-
Piperidyl) sebacate, 1- [2- {3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy}
-2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-
1,2,3-Triazaspiro [4,5] undecane-
2,4-dione, 4-benzoyloxy-2,2,6,
6-tetramethylpiperidine, dimethyl succinate-1-
(2-hydroxyethyl) -4-hydroxy-2,2,
6,6-Tetramethylpiperidine polycondensate, poly [[6
-(1,1,3,3-tetramethylbutyl) imino-
1,3,5-triazine-2,4-diyl] [(2,
2,6,6-Tetramethyl-4-piperidyl) imino]
Hexamethylene [[2,2,6,6-tetramethyl-4
-Piperidyl) imino]], 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl ) And other hindered amine stabilizers, as well as phenolic, phosphite, thioether and other antioxidants.

In the present invention, the mixing method of each component is not particularly limited, and examples thereof include a mixer such as a ribbon blender, a tumbler, a Nauter mixer, a Henschel mixer and a super mixer, or a Banbury mixer, a kneader, a roll, a kneader ruder and a single mixer. It is carried out using a kneader such as a twin-screw extruder or a twin-screw extruder.

The composition of the present invention can be obtained in the form of powder, beads, pellets or a mixture thereof by mixing the respective components, but pellets are preferable because they are easy to handle. The obtained composition is molded by various thermoplastic resin molding machines, preferably an injection molding machine and an extrusion molding machine.

[0022]

The present invention will be described more specifically with reference to the following examples and comparative examples. The details, test methods, and evaluations of each component used in Examples and Comparative Examples will be illustrated, but the present invention is not limited to these without departing from the spirit of the present invention.

Resin-bonded magnet compositions and magnets were produced and evaluated by the following materials and methods. The materials used are shown below.

A magnetic powder-Magnetic powder 1: SmCo ₅ type magnetic powder (trade name: RCo ₅ alloy, manufactured by Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 246 kOe-Magnetic powder 2: Nd-Fe-B type magnetic powder ( (Product name: MQP-B, manufactured by General Motors, USA) Anisotropic magnetic field: 70.4 kOe

B polyamide resin PA: 12 nylon (trade name: UBE nylon, 3014U, Ube Industries, Ltd.)

C polyethylene-ethyl acrylate (EEA) copolymer resin-EEA copolymer resin 1 (trade name: PES-220, manufactured by Nippon Unicar Co., Ltd.)-EEA copolymer resin 2 (trade name: PES-250, Japan) Unicar Co., Ltd.)

D 1 Modified silicone oil in which at least one of terminal group and / or side chain in one molecule has epoxy group and / or glycidyl ether group and / or amino group and / or carboxyl group. Silicone oil 1: side chain amino Modified dimethyl silicone oil (trade name: BY16-850, manufactured by Toray Dow Corning Silicone Co., Ltd.)-Silicone oil 2: side chain glycidyl dimethyl silicone oil (Product number: SF8413, Toray Dow Corning.
Silicone Co., Ltd.-Silicone oil 3: Carboxyl-modified dimethyl silicone oil at both ends (Product number: SF8418, Toray Dow Corning
Silicone oil: Silicone oil 4: Unmodified straight dimethyl silicone oil (Product number: SH200 oil, Toray Dow Corning Silicone)

Next, the manufacturing method and evaluation method of each molded product are as follows. 1. Mixing and preparation of composition To the total amount of each magnetic powder, a predetermined resin and each additive system are added in a predetermined ratio (each part by weight), and sufficiently mixed and stirred in a planetary mixer (40 rpm, 80 ° C). It was again dried in a vacuum oven at −760 mmHg and 120 ° C. for 24 hours.

The mixture obtained by these is 20 mmφ
Extruded with a single extruder (L / D = 25, CR = 2.0, rotation speed = 20 rpm, 5 mmφ strand die, cylinder temperature 200 ° C. to 280 ° C., die temperature 280 ° C.), and hot cut pelletizer 5 mmφ × 5 mm
A pellet compound for a resin-bonded magnet was manufactured.

2. Injection molding method These pellet compounds were used in a magnetic field injection molding machine (J-20MII) manufactured by Japan Steel Works, Ltd. (J-20MII) to measure width 5 mm x length 15
The same conditions are used for the test resin-bonded magnet of 2 mm x 2 mm (molding temperature 240-290 ° C, mold temperature 100-120 ° C).
The obtained molded magnets were evaluated by the methods described below. Incidentally, only when SmCo ₅ was used, molding was performed in a mold in a magnetic field of 15 to 20 kOe.

3. Evaluation methods (i) Mechanical strength (3-point bending strength) evaluation The bending strength of the evaluation sample obtained under the above injection molding conditions was measured using an autograph manufactured by Shimadzu Corporation at a head speed of 2 mm / min. And determined at room temperature. Table 1 shows the results
~ Shown in Table 5. If the bending strength is 5.0 kgf / mm ² or more, the mechanical strength is sufficient.

(Ii) Evaluation of fluidity (MFR) The pelletized composition obtained under the above kneading conditions was measured by a high-performance flow tester manufactured by Shimadzu Corporation (temperature: 250).
° C, Load: 30kgf, Die shape: 1mmφ × 1m
m, preheat: 120 seconds) The fluidity was measured. The results are shown in Tables 1 to 5. It has been found in the fluidity evaluation that if a fluidity of 1.5 g / min or more can be ensured, no problems will be caused in molding.

(Iii) Evaluation of Magnetic Properties The magnetic properties of the resin-bonded magnet samples obtained under the above injection molding conditions were measured at room temperature with a Thiophy type self-recording magnetometer. Tables 1 to 5 show the results of (BH) _max (maximum magnetic energy product) of the magnetic properties.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

INDUSTRIAL APPLICABILITY As described above, the resin composition for resin-bonded magnets of the present invention can be highly filled with magnetic powder, for example, 95 wt%, and has excellent magnetic properties and moldability,
We can provide resin-bonded magnets with excellent physical properties (especially mechanical strength), and applications that require all of formability, magnetic properties, and mechanical strength, such as general household appliances, communication and audio equipment, It is especially useful in a wide range of fields such as medical equipment and general industrial equipment.

Claims (2)

[Claims] 1. _A composition comprising a magnetic powder having an anisotropic magnetic field (H _A ) of 50 kOe or more and one or more polyamide resins, based on 100 parts by weight of the polyamide resin, polyethylene-ethyl. 0.01 to 30 parts by weight of the acrylate copolymer resin, and at least one of the terminal groups and / or side chains in one molecule is an epoxy group and / or a glycidyl ether group and / or an amino group and / or a carboxyl group. A composition for resin-bonded magnets, characterized in that the modified silicone oil having the formula (1) is added in an amount of 0.01 to 10 parts by weight. 2. A resin-bonded magnet obtained by heat-molding the resin-bonded magnet composition according to claim 1.