JP2001185410A - Resin-bonded magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-bonded magnet, which is able to resolve a defect of the magnet using a polyamide resin and has a superior magnetic characteristics and adhesion characteristic. SOLUTION: In the resin-bonded magnet, containing magnetic power having rare earth element and a polyamide resin as its main component, having water content of 0.03 wt.% or more and having a carboxyl group structure which is modified its amino-terminal group of a polyamide resin by a chemical component containing a carboxy group. A functional group in the chemical compound having a carboxy group is desirable to contain at least two or more carboxy group.

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 and adhesive properties.

[0002]

2. Description of the Related Art Magnets are small motors, audio equipment, OA
It is used for various purposes such as equipment. The resin-bonded magnet is formed by filling a thermoplastic resin such as a polyamide resin or a polyphenylene sulfide resin as a binder and filling them with magnetic powder. It is difficult to obtain brittle, thin-walled or complicated-shaped magnets manufactured by the sintering method, and high shrinkage during sintering is as large as 15 to 20%. The disadvantage is not the resin-bonded magnet.

[0003]

However, conventional resin-bonded magnets have insufficient magnetic properties, especially for products of complex shapes which are difficult to mold. In addition, when a polyamide resin is used as the binding resin, there is a problem in adhesiveness with other materials at the time of assembling parts into a motor or the like.

Accordingly, an object of the present invention is to eliminate the drawbacks of conventional thermoplastic resin-bonded magnets, particularly magnets using a polyamide resin, and to provide a resin-bonded magnet having particularly excellent adhesive properties.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have modified the method of modifying the terminal amino group of the polyamide resin, the type of molecular weight, additives, etc., and the content of water by changing the content. And completed the present invention.

That is, the resin-bonded magnet of the present invention is a resin-bonded magnet mainly comprising a magnetic powder containing a rare earth element and a polyamide resin, wherein the terminal amino group of the polyamide resin has a carboxyl group. It is characterized by having a terminal carboxyl group structure modified with a compound to be contained.

It is desirable that the functional group in the carboxyl group-containing compound contains at least two or more carboxyl groups. As the compound containing a carboxyl group, for example, a dicarboxylic acid compound or a tricarboxylic acid compound can be selected.

It is desirable that the compound containing a carboxyl group is a compound having 1 to 10 carbon atoms excluding the carboxyl group.

The residual amount of the terminal amino group after the modification is 1
Desirably, it is not more than 00 mmol / kg.

The number average molecular weight of the terminal amino group-modified polyamide resin is desirably 4,000 to 20,000.

As the polyamide resin, for example, nylon 11 or nylon 12 can be selected.

In the resin-bonded magnet of the present invention, 0.03
Contains at least water by weight.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic powder containing a rare earth powder used in the present invention has an anisotropic magnetic field (HA) of 50 kOe or more,
If a rare earth element is included in the constituent elements, those usually used can be used. For example, rare earth cobalt system,
Magnetic powders such as rare earth-iron-boron and rare earth-iron-nitrogen are exemplified.

In particular, when an Nd-Fe-B-based alloy powder obtained by a liquid quenching method or an Sm-Fe-N-based alloy powder is used, high filling of, for example, 95% by weight or more is possible, and particularly excellent. A resin-bonded magnet having magnetic properties can be obtained.

The effect of the present invention is particularly large when a magnetic powder containing an iron element is used, and the ratio of high magnetic properties including remarkable improvement in the formability is remarkable.

Nd-Fe- obtained by the liquid quenching method
Since the B-based magnetic powder has a unique scale-like shape, it is preferable to grind it with a jet mill, a ball mill, or the like. The preferred particle size of these magnetic powders is 20 on average.
It is 0 μm or less, particularly preferably 100 μm or less on average.

These magnetic powders can of course be used as they are, but it is desirable to coat the surfaces with various surface treatment agents in order to minimize oxidation deterioration during kneading and molding.

Materials that can be surface-treated include silane coupling agents, titanium coupling agents, aluminum coupling agents, phosphoric acid surface treatment agents, chromic acid surface treatment agents, zinc phosphate surface treatment agents, and phosphoric acid. Phosphoric acid-based and phosphate-based surface treating agents such as manganese-based surface treating agents, iron phosphate-based surface treating agents, and calcium phosphate surface treating agents.

In particular, by treating the surface of the magnetic powder in advance with a phosphoric acid-based surface treatment agent or a phosphate-based surface treatment agent to form a composition in a later step, it is possible to minimize the decrease in magnetic properties. .

An organosiloxane-based surface film, a mixed surface film of an organosiloxane and an organosilica sol,
Mixed surface film of organosiloxane and acrylic monomer, polyorganosilsesquioxane (ladder type organosiloxane polymer) surface film, hexamethyldisilazane surface film, polysilazane (perhydropolysilazane), silicon oxide, etc. The use of a magnetic powder on which a single or mixed inorganic coating film is formed makes it possible to minimize the decrease in magnetic properties.

The resin-bonded magnet of the present invention is characterized in that a polyamide resin in which a terminal amino group is modified to a carboxyl group is used.

The polyamide resin before modification includes, for example, 6 nylon, 6, 6 nylon, 11 nylon, 12 nylon, 6, 12 nylon, and aromatic nylon. In addition, these copolymers and random copolymers with other monomers, block copolymers, graft copolymers, end group-modified products with other substances, and two or more of these thermoplastic resins The system in a blend etc. is also mentioned.

Of these, nylon 11 and nylon 12 are preferred from the viewpoint of moldability.

In the conventional polyamide resin, the special reactivity with the iron group contained in the magnetic powder to be mixed significantly changes the melt viscosity of the composition during heat-kneading or injection molding, resulting in impaired moldability. However, these modifications can be greatly improved by modifying the terminal amide group.

After the modification, the residual amount of terminal amide groups is 10
0 mmol / kg or less, more preferably,
It is 50 mmol / kg or less. When the amount of the remaining terminal amide group is larger than these amounts, the reaction with the magnetic powder, particularly the magnetic powder containing iron element becomes remarkable, which causes an increase in melt viscosity and a decrease in fluidity.

The carboxyl-containing compounds used for the modification include dicarboxylic compounds such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid and fumaric acid, and aromatic compounds such as phthalic acid and naphthalenedicarboxylic acid. And the like dicarboxylic compounds. This compound is preferably linear. Further, the number of carbon atoms excluding the carboxyl group of this compound is desirably 1 or more and 10 or less. If the number of carbon atoms is less than 1, no effect of improving moldability is obtained. Invite.

The average molecular weight of the modified polyamide resin is preferably from 4,000 to 20,000. 4000
If it is less than 2,000, the strength of the molded article is remarkably reduced, and practicality is lacking. If it exceeds 20,000, the moldability deteriorates.

The shape of the modified polyamide resin is not particularly limited, such as powder, beads, pellets, etc., but powder is desirable from the viewpoint of uniform mixing with the magnetic powder.

The amount to be added is preferably from 5 to 50 parts by weight, preferably from 8 to 20 parts by weight, more preferably from 8 to 15 parts by weight, based on 100 parts by weight of the magnetic powder. Is more preferred. When the addition amount of the polyamide resin is less than 5 parts by weight based on 100 parts by weight of the magnetic powder, the moldability is remarkably reduced, and a desired resin-bonded magnet cannot be obtained. If the amount exceeds 50 parts by weight, desired magnetic properties cannot be obtained.

The resin-bonded magnet according to the present invention is characterized in that, in addition to the above-mentioned magnet powder and modified polyamide resin, the molded resin-bonded magnet compact contains a certain amount of water or more.

As a method for containing moisture, for example, a method in which the resin-bonded magnet is left in a constant-temperature and constant-humidity tank maintained at a constant humidity and temperature for a predetermined time can be used. The amount of water to be contained must be at least 0.03% by weight of the weight of the resin-bound magnet. If the content is less than this, the bonding strength at the time of bonding to another material component in a subsequent step will be weak. In order to sufficiently obtain the effects of the present invention, it is desirable that the content is preferably 0.05% by weight or more, more preferably 0.08% by weight or more.

In addition to these essential components, resins other than polyamide resins, lubricants for plastic molding, various stabilizers and the like can be optionally contained.

Resins other than polyamide resins that can be added include polyethylene resins, polypropylene resins, polybutene resins, polymethylpentene resins, ethylene-vinyl acetate copolymer resins, ethylene-ethacrylate copolymer resins, ethylene-methacrylate copolymer resins, Chlorinated polyethylene resins, including polyolefins such as partially oxidized polyethylene resins and their copolymer resins, polyethylene terephthalate resins, polybutylene terephthalate resins,
Polyacetal resin, polycarbonate resin, polyphenylene oxide resin, polyarylate resin, polysulfone resin, polyamideimide resin, polyphenylene sulfide resin, cellulose acetate, cellulose acetate butyrate,
Polystyrene resin, polybutadiene resin, polyacrylonitrile resin, styrene-butadiene copolymer resin, styrene-acrylonitrile copolymer resin, acrylonitrile-butadiene-styrene copolymer resin, acrylate-styrene-acrylonitrile resin, chlorinated polyethylene-
Acrylonitrile-styrene copolymer resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polymethyl methacrylate resin, polybutyl methacrylate resin, polytetrafluoroethylene resin, ethylene-polytetrafluoroethylene copolymer resin and the like. Can be

Examples of the lubricant include monocarboxylic saturated fatty acids such as propionic acid, butyric acid, valeric acid, lauric acid, palmitic acid, stearic acid and behenic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid and the like. Dicarboxylic saturated fatty acids, acrylic acid, linoleic acid, monocarboxylic unsaturated fatty acids such as oleic acid,
Maleic acid, dicarboxylic unsaturated fatty acids such as fumaric acid and the like, and the compounds thereof include, for example, calcium stearate, barium stearate,
Fatty acid metal salts (metal soaps) such as magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate, 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 acid amide, distearyladipamide, ethylenebisoleic acid Fatty acid amides such as amide, dioleyl adipamide, N-stearyl stearamide, fatty acid esters such as butyl stearate, paraffin wax, liquid paraffin, poly Chirenwakkusu, polypropylene wax, ester wax, carnauba wax such as micro wax, ethylene glycol, alcohols such as stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and polyethers consisting modification thereof,
Polysiloxanes such as dimethylpolysiloxane and 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. Body.

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]], bis (1,2,2,6,6-pentamethyl-4-piperidyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate ), Antioxidants such as phenolic, phosphite, thioether and the like.

In addition to the above, pigments, various modifiers for plastics, compatibilizers and the like may be added as needed, but the composition after final kneading is JIS K 7210.
It is preferable that the flow value Q of the molten composition at a load of 30 kgf and a measurement temperature of 250 ° C. is 50 ml / sec or more when the die B is used according to the “flow test method (reference test)”.

In the present invention, the method of mixing these components before forming the magnet is not particularly limited. For example, a mixer 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, a single-screw extruder, a twin-screw extruder or the like.

These can be obtained in the form of powder, beads, pellets or a mixture thereof by mixing the respective components, but pellets are preferable in terms of easy handling. The magnet precursor composition obtained here is molded by various thermoplastic resin molding machines, preferably an injection molding machine or an extrusion molding machine, and can be obtained as a desired resin-bonded magnet.

[0039]

The present invention will now be described more specifically with reference to examples and comparative examples. The details, test methods, and evaluations of each component used in the examples and comparative examples will be described, but the examples are not limited thereto without departing from the spirit of the present invention.

A magnet was manufactured with the following materials and methods and evaluated. The following materials were used for the magnetic powder. -Magnetic powder 1: Nd-Fe-B-based magnetic powder (average particle diameter 100 m) (trade name: MQP-B, manufactured by Magnequench International Co., Ltd.)-Magnetic powder 2: Sm-Fe-N-based magnetic powder (trade name: SmFeN alloy, manufactured by Sumitomo Metal Mining Co., Ltd.) Magnetic powder 3: Strontium ferrite magnet powder (trade name: MA-951, manufactured by Toda Kogyo Co., Ltd.)

Next, the production method and evaluation method of each molded product will be described. Preparation of Nylon with Modified End Group Nylon 12 (UBE3014U) 1 manufactured by Ube Industries, Ltd.
A predetermined dicarboxylic acid compound (here, malonic acid) was added to 00 parts by weight, and the mixture was charged into a universal mixer and reacted at 250 ° C. in a nitrogen atmosphere at 1.3 atm for 3 hours. After cooling, a desired nylon was obtained. . The remaining terminal amino group was identified by a terminal group quantification method by a titration method. The number average molecular weight was calculated by the GPC method.

Mixing and preparation of resin-bonded magnet molding composition A predetermined resin is added to each of the coated magnetic powders in a predetermined ratio (each part by weight). Parts were added to each of the specified amounts, and thoroughly mixed and stirred in a planetary mixer.

The obtained mixture was subjected to a 20 mmφ single extruder (L / D = 25, CR = 2.0, rotation speed = 20 rpm).
m, 5mmφ strand die, cylinder temperature 200 ~
The mixture was extruded at 230 ° C. and a die temperature of 200 ° C., and was made into a 5 mmφ × 5 mm pellet compound for a resin-bonded magnet by a hot cut pelletizer.

Injection molding These pellet compounds were processed by a magnetic injection molding machine (J-20MII) manufactured by Nippon Steel Works Co., Ltd.
A 15 mm cylinder and a 6 mm × 15 mm × 2 mm test resin-bonded magnet were used under the same conditions (forming temperature 220 to 230 ° C.,
Molding was performed at a mold temperature of 100 to 120 ° C.), and the obtained magnet molded products were evaluated by the methods described below.
In addition, only when SmFeN-based magnet powder is used,
Molding was performed in a mold in a magnetic field of kOe.

Evaluation Methods Magnetic Property Evaluation 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 self-recording magnetometer. Tables 1 to 6 show the results of the coercive force (iHc) among the magnetic characteristics.
It is shown in the table.

Evaluation of Adhesive Strength Two pieces (one set) of 6 mm × 15 mm × 2 mm shape test pieces were bonded with a cyanoacrylate adhesive so that only a 6 mm × 7 mm portion was overlapped, and after 24 hours, Shimadzu Corporation 2) Non-overlapping parts on both sides were grasped by an autograph, and tensile shear was applied at 1 mm / min, and the strength at the time of breaking was observed. Five sets of tests were performed for one sample, the average value was determined, and relative values were calculated with the value of “Comparative Example 2” taken as 100 and compared. The results are shown in Tables 1 to 6.

Measurement of water content After various moisture absorption treatments were performed on 20 pieces of a 6 mm × 15 mm × 2 mm sample, only 10 of the pieces were treated as 1
The sample was allowed to stand in an oven at 10 ° C. in an atmosphere of about 10 ⁻² Torr for 24 hours, and the change in weight before and after that time was defined as the water content, the water content was calculated, and the average value was obtained. Table 1 to Table 6 show the results.
Shown in

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

[Table 6]

The magnets of the examples of the present invention are superior in both magnetic properties and adhesive strength as compared with the comparative examples.

[0055]

As described above, the resin-bonded magnet of the present invention uses a magnetic powder and a polyamide resin in which a terminal amino group is modified to a carboxyl group to provide a resin-bonded magnet having more excellent magnetic properties. Can be provided.

Claims (8)

[Claims] 1. A resin-bonded magnet comprising a magnetic powder containing a rare earth element and a polyamide resin as main components, wherein a terminal amino group of the polyamide resin is modified with a compound containing a carboxyl group. A resin-bonded magnet having a base structure. 2. The resin-bonded magnet according to claim 1, wherein the functional group in the carboxyl group-containing compound contains at least two or more carboxyl groups. 3. The resin-bonded magnet according to claim 1, wherein the compound having a carboxyl group is a dicarboxylic acid compound or a tricarboxylic acid compound. 4. The resin-bonded magnet according to claim 1, wherein the compound having a carboxyl group is a compound having 1 to 10 carbon atoms excluding the carboxyl group. 5. The method according to claim 1, wherein the remaining amount of the terminal amino group after the modification is 100
2 mmol / kg or less.
5. The resin-bonded magnet according to any one of 4. 6. The resin-bonded magnet according to claim 1, wherein the polyamide resin having a terminal amino group modified has a number average molecular weight of 4,000 to 20,000. 7. The polyamide resin is 11 nylon,
Or 1 and 12 nylon.
7. The resin-bonded magnet according to any one of claims 6 to 6. 8. The resin-bonded magnet according to claim 1, wherein the resin-bonded magnet contains 0.03% by weight or more of water.