JP2002043109A - Surface treatment method of rare earth-iron-nitrogen magnetic power and plastic magnet formed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide rare earth-iron-nitrogen magnetic powder and to enable a plastic magnet formed of the magnetic powder to be improved in oxidation resistance, weather resistance, and magnetic characteristics. SOLUTION: A phosphate compound is mixed into rare earth-iron-nitrogen magnetic powder, so as to enable P which originates from phosphate to be within a range of from 0.05 to 3 pts.wt. with respect to the magnetic powder of 100 pts.wt., and the mixture is dried out. The surfaces of the magnetic particles are covered with the phosphate compound, and then the magnetic particles covered with the phosphate compound are thermally treated at a temperature range of from 130 to 300 deg.C in an oxygen-containing atmosphere in a surface treatment method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a rare earth-iron-nitrogen magnetic powder with a phosphoric acid compound, and relates to a technique for improving the heat resistance, magnetic properties and the like of the magnetic powder.

[0002]

2. Description of the Related Art A plastic magnet is also called a bonded magnet, and a magnetic powder (magnetic powder) is mixed with a thermoplastic resin such as a polyamide resin or a polyphenylene sulfide resin, a thermosetting resin such as an epoxy resin or a polyimide resin as a binder. It is formed by performing necessary processing.
Ferrite has been used as a magnetic powder for plastic magnets, but fine powder of rare earth magnets having high crystal magnetic anisotropy has been used as magnetic powder.

[0003] In the production of plastic magnets, they are exposed to high temperatures during kneading or molding of magnetic powder and resin. Rare earth magnet powder is a metal alloy unlike ferrite, and is very easily oxidized because it contains a rare earth element in its constituent components. Therefore, there is a very serious problem that the rare earth plastic magnet is easily oxidized in the manufacturing process and the magnetic properties of the resulting rare earth plastic magnet are significantly deteriorated.

To cope with such a problem, techniques for improving heat resistance by coating a rare earth magnet powder with a phosphoric acid or phosphate compound are disclosed in Japanese Patent Application Laid-Open Nos. 60-240105 and 61-253302. JP-A-63-28109, JP-A-11-135314, JP-A-2000-
No. 58312. However, these phosphate coatings are not sufficient in adhesiveness to magnetic powder, denseness of the coating, and the like. In particular, the application to a plastic magnet using a rare earth-iron-nitrogen based magnetic powder having a large specific surface area is still insufficient.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide an oxidation resistance, a weather resistance, and a magnetic property of a plastic magnet using a rare earth-iron-nitrogen based magnetic powder. And so on.

[0006]

Means for Solving the Problems The present inventor has made it possible to stabilize the magnetic powder by coating the surface of the magnetic powder with a phosphoric acid compound densely and with good adhesive strength, thereby improving the performance of the plastic magnet. As a result of intensive studies on the coating method, the present invention was completed.

That is, the present invention provides a rare earth-iron-nitrogen based magnetic powder in which P derived from phosphoric acid of a phosphoric acid compound is in a range of 0.05 to 3 parts by weight based on 100 parts by weight of the magnetic powder. After mixing and drying, and coating the particle surface with a phosphoric acid compound, 130-
It is characterized by heating at a temperature in the range of 300 ° C.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The rare earth-iron-nitrogen based magnetic powder of the present invention is a rare earth iron-nitrogen based alloy powder represented by the composition formula of RxFeyNz, where R represents one or more rare earth elements, and x represents 0.03 to 0.30, y is 0.55 to 0.9
2, z is in the range of 0.05 to 0.15 (provided that x +
y + z does not exceed 1) applies to alloy powders. The rare earth element R is preferably used because Sm is particularly excellent in magnetic properties. When R is Sm, magnetic powder having a target composition of Sm2Fe17N3 is most preferable in terms of magnetic properties. The magnetic powder
An alloy powder comprising such a rare earth metal, iron and nitrogen, wherein the powder has an average particle diameter of 10 μm or less and a particle diameter in the range of 0.40 to 1.80 times the average particle diameter. It is prepared so as to account for at least 80% by weight of the composition. In order to improve the magnetic properties, especially the coercive force, the average particle size is preferably small, and the average particle size is 3 μm in view of the balance with the residual magnetization.
In the following, 1-2 μm is particularly preferred.

As the magnetic powder used in the present invention, an ordinary method for producing a rare earth-iron-nitrogen based magnetic powder can be applied. For example, a method of melting a rare earth metal and iron to form an ingot, pulverizing the ingot and then nitriding, or mixing Ca in a mixture of a rare earth oxide powder and an iron powder, heating at a high temperature, performing reduction diffusion, and then nitriding Each of the methods has the effect of improving the heat resistance, oxidation resistance, rust prevention and magnetic properties of the present invention, but the latter is superior.

The phosphoric acid compound in the present invention is not limited to orthophosphoric acid, but is an inorganic or organic compound containing a functional group such as metaphosphoric acid, pyrophosphoric acid, triphosphoric acid or tetraphosphoric acid in the compound. Has hydrogen that can be ionized.
Accordingly, metal phosphates are excluded, but metal phosphates in which a metal is partially replaced with hydrogen are included.

Among the above-mentioned phosphoric acid compounds, a type in which the reaction between the rare earth-iron-nitrogen magnetic powder and the aqueous solution of the phosphoric acid compound progresses relatively slowly can be preferably used. That is, the phosphoric acid compound is dissolved in water to prepare an aqueous solution having a pH of 2. 5 g of the desired magnetic powder is added to 10 g of this aqueous solution.
Was added and the mixture was stirred and mixed for 30 minutes.
0)), and the rate of change r = (pH (30) -2) / 2 × 100 is calculated, and it is preferable to use a phosphoric acid compound that is less than 5%. .

As the value of r increases, the rate of precipitation of the phosphate compound also increases, and the precipitated phosphate compound particles tend to aggregate. When the degree of this aggregation increases,
The adhesion between the magnetic powder and the phosphate decreases, the coating on the surface of the magnetic powder particles becomes coarse, and the gaps increase. As a result, the effect of the phosphoric acid compound, such as oxidation resistance, decreases. In addition, a steric hindrance caused by the phosphoric acid compound requires a large orientation magnetic field for the orientation of the production of the magnetic powder bonded magnet, and when the degree of aggregation is further increased, the magnetic particles are also aggregated between the magnetic particles, making the orientation more difficult. Accordingly, the phosphoric acid compound has a rate of change r of preferably less than 5%, more preferably less than 4%, and most preferably 2%.
It is as follows.

As a phosphoric acid compound in which r is less than 5%,
Lauryl phosphate, stearyl phosphate, 2-ethylhexyl phosphate, isodecyl phosphate, butyl phosphate, monoisopropyl phosphate, propyl phosphate, aminotrimethylene phosphonic acid, hydroxymethyl acrylate acid phosphate, hydroxymethyl methacrylate acid phosphate, (2- (Hydroxyethyl) acrylate acid phosphate and (2-hydroxyethyl) methacrylate acid phosphate.

The amount of the magnetic powder to be added to the obtained aqueous solution of the phosphoric acid compound is such that P derived from the phosphoric acid of the phosphate group contained in the phosphoric acid compound is 0.05 to 3 parts by weight based on 100 parts by weight of the magnetic powder. It is mixed with the magnetic powder so as to be in the range. In the case of 0.05 parts by weight or less, even if iron on the surface of the magnetic powder and the rare earth element react with hydrogen ions and are ionized, there is a shortage of a phosphoric acid compound for stabilizing the ions. No effect can be expected. If the amount is more than 3 parts by weight, the cost increases and unnecessary phosphoric acid compounds are precipitated on the surface of the magnetic powder, and the filling property of the magnetic substance is reduced.

The surface of the magnetic powder thus obtained is
Coated with a phosphate compound. Although the problem of heat resistance is improved to some extent by this, it is practically impossible to coat the surface of the magnetic powder with a phosphoric acid compound without gaps, and active iron atoms or rare earth metal atoms are present in the gaps. This becomes a so-called active point. When such a magnetic powder is mixed with a thermoplastic resin and kneaded at, for example, 250 ° C., oxidation progresses from the active point to the inside of the magnetic powder, resulting in a significant decrease in magnetic properties. Cause, and furthermore, cause degradation of the resin.

An important feature of the present invention is that the above-described process of inactivating the active sites that induce the deterioration of the plastic magnet before kneading with the resin is performed. That is, by performing the heat treatment at a temperature in the range of 100 to 300 ° C. in an atmosphere containing oxygen, the active points are oxidized and inactivated.

The present invention will be described with reference to FIGS. These are subjected to a phosphoric acid treatment using stearyl phosphoric acid as a phosphoric acid-based compound, and then water is removed.
Diagram plotting the relationship between coercive force (iHc) and heating time of a magnetic powder obtained by subjecting a rare earth-iron-nitrogen-based magnetic powder vacuum-dried at 2 ° C. for 2 hours to a heat treatment (O 2 = 20%) in air. It is. The solid line is the magnetic powder itself that has been subjected to the heat treatment, and the dotted line is the characteristic as a result of performing a heat resistance test on the magnetic powder. Here, the heat resistance test was conducted by placing the magnetic powder in a heating vessel and placing it in the atmosphere.
Heating at 50 ° C. for 30 minutes. When the magnetic powder is finished into a bonded magnet, the magnetic powder is degraded by heat and physical stress in the kneading process. Among the tests, only the thermal damage can be separated and inspected.

In FIGS. 2 to 6, the heat treatment temperatures are 100 ° C., 150 ° C., 200 ° C., 250 ° C., and 300 ° C., respectively.
° C, the coercive force was 16 max.
kOe is almost reached. The time to reach this maximum is 8 hours at 100 ° C, 4 hours at 150 ° C, 20 hours.
It takes 2 hours at 0 ° C., 1 hour at 250 ° C., and 0.5 hour at 300 ° C.

In the case where the heat treatment was performed under the heating condition (temperature and time) which almost reached the maximum value of 16 kOe, the holding power did not decrease by the heat resistance test.

On the other hand, as shown in FIG.
In the case where the heat treatment was performed at 0 ° C., the coercive force did not reach the maximum value no matter how long the heating was performed. As a result of the heat resistance test, a decrease in coercive force is observed.

Further, as shown in FIG. 7, the heat treatment at 320 ° C. has a high coercive force where the heating time is extremely short, but the maximum value of the coercive force reached at 100 to 300 ° C. It cannot reach 16 kOe, and the coercive force tends to decrease over time. As a result of the heat resistance test, a decrease in coercive force is observed.

Therefore, in the present invention, the heating after the phosphoric acid treatment is required to be in the range of 100 ° C. to 300 ° C.
A temperature in the range of 250 ° C. is preferred from the standpoint of ease of manufacture using a heat treatment. The optimum heat treatment condition is that the holding power hardly decreases (less than several percent) even after the heat resistance test in the above temperature range.

The above experimental results show that the oxidation reaction of the active point of the magnetic powder by oxygen is incomplete at a temperature lower than 100 ° C. Conversely, when the magnetic powder is heated at a temperature higher than 300 ° C., the active point on the surface of the magnetic powder particle is insufficient. In addition, it can be estimated that oxidation proceeds from the active point to the inside of the magnetic powder, and the magnetic properties of the magnetic powder have deteriorated, and as a result, the coercive force has decreased.

Although only the coercive force has been described above, the remanent magnetization σr did not fluctuate to 130 emu / g.

The present invention will be described with reference to FIGS. These are treated with a phosphoric acid treatment, and after removing moisture, vacuum-dried at 150 ° C. for 2 hours to a rare earth-iron-nitrogen-based magnetic powder.
%, 5%, 20%, 50%, 80%, and 100% are plots showing the relationship between the coercive force (iHc) of the magnetic powder obtained and the heating temperature. The heating time was 2 hours in each case. The solid line is the magnetic powder itself that has been subjected to the heat treatment, and the dotted line is the characteristic as a result of performing a heat resistance test on the magnetic powder.

9 to 13, the oxygen atmospheres are 5%, 20% (in air), 50%, 80%, 10%, respectively.
In the case of 0%, the coercive force almost reaches the maximum value of 16 kOe. When the O2 concentration is 5%, around 320 ° C., when the O2 concentration is 20%, around 200 ° C., when the O2 concentration is 50%, around 160 ° C., when the O2 concentration is 80%, around 130 ° C.,
When the O2 concentration is 100%, the maximum value of 16
It has almost reached 0 kOe. However, when O2 is 0%, the coercive force does not reach the maximum value no matter how high the temperature.

In the case where the heat treatment was performed under the heating conditions (O2 concentration and heating temperature) that reached the maximum value of 16 kOe, no decrease in the holding power due to the heat resistance test was observed.

If the O2 concentration is very small, the effect of the heat treatment can be confirmed by heating at a high temperature for a long period of time. However, the heating cost is increased, which is uneconomical and not very suitable. Conversely, when O2 is 100%, the maximum coercive force is relatively difficult to control because the heating temperature is limited to a very narrow range around 100 ° C. From these results, the oxygen concentration is preferably 5% or more, and more preferably 20%.
８０80%.

In the present invention, the effect of the heat treatment is improved by vacuum drying before the heat treatment. FIG. 14 shows the effect on the coercive force and the residual magnetization when the drying conditions in the pre-process of the heat treatment are changed. Those dried in vacuum at 150 ° C. have the highest coercive force of 16 kOe. Without vacuum drying
The coercive force is reduced to 15 kOe when dried at 90 ° C. in the air, and the coercive force is 9.2 when heat-treated without drying.
It is remarkably reduced to kOe. 7kO after heat resistance test
e.

The magnetic powder obtained by the above-described method was mixed with additives such as thermoplastic resin (12 nylon), a coupling agent, and a lubricant, kneaded at about 250 ° C., molded to produce a plastic magnet, and compared. However, even when kneaded and molded at a high temperature, the magnetic powder did not undergo oxidative deterioration, and the magnetic properties of the molded product did not deteriorate from the properties of the magnetic powder. The magnetic properties reflected the tendency of the magnetic properties of the magnetic powder after the heat test.

Further, the coercive force of the magnetic powder is 16 kO, which is the highest value.
The plastic magnet showing a value of about e has an initial demagnetization rate of 1 at 100 ° C. in the atmosphere when the permeance coefficient is 2.
% Or less.

When a plastic magnet is produced using the magnetic powder of the present invention, a resin commonly used as a binder for a rare earth magnet is used, and a thermoplastic resin, a thermosetting resin,
At least one of an elastomer, a thermoplastic elastomer, etc.
Species or two or more can be used.

As the thermoplastic resin, 12-nylon,
Polyamide resin such as 6,12-nylon, 4,6-nylon, 6,10-nylon, nylon 6T, nylon MXD6, aromatic nylon, 11-nylon, amorphous nylon, copolymer nylon, polyethylene, high density Olefin resins such as polyethylene, low-density polyethylene and polypropylene Iomer resins such as ethylene-iomer resins, EEA resins such as ethylene-ethyl acrylate copolymer, acrylonitrile-acryl rubber-styrene copolymer resins, acrylonitrile-styrene copolymer resins Acrylonitrile-based resins such as acrylonitrile-butadiene-styrene copolymers, acrylonitrile-chlorinated polyethylene-styrene copolymers, polyvinyl-based resins such as ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, and acetate fibers. Polyethylene resin, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexylfluoropropylene copolymer, tetrafluoroethylene / ethylene polymer, fluorine such as polyvinylidene fluoride, polyvinyl fluoride Resin, polymethyl methacrylate, acrylic resin such as ethylene / ethyl acrylate resin, polyurethane resin, aromatic polyester resin, polyacetal, polycarbonate, polysulfone, polybutylene terephthalate, polyethylene terephthalate, polyarylate, polyphenylene oxide,
Polyphenyl sulfide, polyoxypendylene, polyether ketone, polyether sulfone, polyether imide, polyamide imide, polyimide, polyallyl ether nitrile, polybenzimidal, polyaramid, polyester amide, wholly aromatic amide, semi-aromatic At least one kind or two or more kinds of engineering plastics such as liquid crystal resins such as amides and super engineering plastics can be used.

Examples of the thermosetting resin include epoxy resin, phenol resin, amide special resin, epoxy-modified phenol resin, unsaturated polyester resin, xylene resin, urea resin, melanin resin, silicone resin, alkyd resin, furan resin, and thermosetting resin. At least one kind such as a curable acrylic resin and a thermosetting fluororesin can be used.

As the elastomer, natural rubber, nitrile / butyl rubber, polyisoprene rubber, silicon rubber,
Fluororubber, thermoplastic urethane elastomer such as ester, special ester ether, caprolactone, adipate, carbonate, lactone, etc., olefin thermoplastic elastomer, styrene thermoplastic elastomer, styrene / butadiene heat At least one or two or more thermoplastic elastomers such as a thermoplastic elastomer, a polyamide-based thermoplastic elastomer, a polyester-based thermoplastic elastomer, a nitrile-based thermoplastic elastomer, a hydrogenated SBS-based thermoplastic elastomer, and a fluorine-based thermoplastic elastomer can be used.

In the present invention, the wettability between the magnetic powder and the resin,
A coupling agent can be used for the purpose of improving the strength of the magnet. The coupling agent is selected according to the type of the resin.

As coupling agents that can be used in the present invention, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxy Propyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ- Mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethylenedisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octane Decyl [3- (trimethoxythryl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltris (βmethoxyethoxy ) Silane, vinyltriethoxysilane, β-
(3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyl Dimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, oleidopropyltriethoxysilane, γ-isocyanatopropyltriethoxysilane, polyethoxydimethylsiloxane, polyethoxymethylsiloxane, bis ( Trimethoxysilylpropyl)
Amine, bis (3-triethoxysilylpropyl) tetrasulfane, γ-isocyanatopropyltrimethoxysilane, vinylmethyldimethoxysilane, 1,3,5
-N-tris (3-trimethoxysilylpropyl) isocyanurate, t-butylcarbamate trialkoxysilane, N- (1,3-dimethylbutylidene) -3-
Silane coupling agents such as (triethoxysilyl) -1-propanamine, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl (N-aminoethyl-aminoethyl) titanate, isopropyl tris (dioctyl pyrophosphate) ) Titanate, tetraisopropylbis (dioctylphosphite) titanate,
Tetraisopropyl titanate, y tetraoctyl bis (trioctyl phosphite) titanate, isopropyl trioctyl titanate, isopropyl tri (dioctyl phosphate), isopropyl dimethacrylate isostearyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra (2, 2-
Titanate cups such as diallyloxymethyl-1-butyl) bis (di-tridecylphosphite) titanate, bis (dioctylpyrophosphate) oxyacetate titanate, isopropylisostearoyldiacryl titanate, and bis (dioctylpyrophosphate) ethylene titanate Examples include a ring agent and an aluminum-based coupling agent such as acetoalkoxyaluminum diisopropylate. At least one or two or more of these coupling agents can be used. The addition amount is 0.01% by weight to 10% by weight. 0.01% by weight
In the following, the effect of the coupling agent is small, and at 10% by weight or more, the magnetic properties of the rare earth magnetic powder and the rare earth magnet are reduced due to aggregation of the rare earth similar powder.

In the present invention, an antioxidant can be added for the purpose of preventing the deterioration of the binder resin due to the heat history during kneading and molding. As an antioxidant, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4)
-Hydroxyphenyl) propionate], 1,6-hexanenediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4
-Bis- (n-octylthio) -6- (4-hydroxy-
3,5-di-t-butylalinino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate] 2,2-thio-diethylenebis [3- (3
5-di-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2 thiobis (4-methyl-6-t-butylphenol) ),
N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydroxycinamide), 3,5
-Di-butiru-4-hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl 2,4,6-tris (3,5-di-t-butyl-4-
Hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxy) Phenyl) propionyl] hydrazine, decamethylenedicarboxylic acid disalicyloylhydrazide, N, N-dibenzal, N, N-bis (3,5-di-t-butyl-4-hydroxyhydrocinnamate,
Tris (2,4-di-t-butylphenyl) phosphite, 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (3,5-di-butyl-4)
-Hydroxyphenyl) propionates, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2-t-butyl-6- (3'-t-butyl-5 '
-Methyl-2'hydroxybenzyl) -4-methylphenyl acrylate, 4,4'-butylidene-bis- (3
-Methyl-6-t-butylphenol, 4,4'-thiobis (3-methyl-6-t-butylphenol), 1,
3,5-tris (4-t-butyl-3-hydroxy-
2,6-dimethylbenzyl) isocyanurate, tetrakis [methylene-3- (3,5′-di-t-butyl-
4'-hydroxyphenyl) propionate] methane,
3,9-bis [2- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-
Dimethylethyl) 2,4,8,10-tetraoxaspiro [5,5] undecane, N, N'-diallyl-p-phenylenediamine, diauryl-3,3'-thiodipropionate, dimyristyl-3,3 '-Thiodipropineate, pentaerythritol-tetrakis (β-laurylthiopropionate), ditridecyl-3,3'-
Thiodipropionate, 2-mercaptobenzimidazal, thiophenylphosphite, tris (2,4-
Di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4′biphenylenephosphonite, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-
Di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole,
2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, poly [{6- (1,1,3,3)
3- (tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5- Bis (1,2,2,6,6-pentamethyl-4-piperidyl) di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, N, N'-bis (3-aminopropyl) Ethylenediamine-2,4-bis [N-butyl-
N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4 -Methoxybenzophenone, 2
-Hydroxy-4-octoxybenzophenone, 2,
2'-di-hydroxy-4-methoxybenzophenone,
2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- [2'hydroxy-3'-
(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2- [2′-hydroxy-3′-t-butyl-5 ′ -Methylphenyl] -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-t-butylphenyl] benzotriazole, 2- [2'-hydroxy-5'-t-octylphenyl] benzo Triazole, 2- [2′-hydroxy-3 ′, 5′-di-t-amylphenyl] benzotriazole, 1,2,3-benzotriazole, tolyltriazole, tolyltriazoleamine salt, tolyltriazole potassium salt, 3-
(N-salicyloyl) amino-1,2,4-triazole, 2,4-di-t-butylphenyl-3 ′, 5′-dibutyl-4′-hydroxybenzoate, nickel dibutyldithiocarbamate, 1,1 -Bis- (4-hydroxyphenyl) cyclohexane, styrenated phenol, N.P. N′-diphenyl-p-phenylenediamine,
N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine, 2,2,4-trimethyl-
1,2-dihydroquinoline polymer, 6-ethoxy-2,
2,4-trimethyl-1,2-dihydroquinoline, phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4 ′-(α, α
-Dimethylbenzyl) diphenylamine, p- (p-toluenesulfonylamide) diphenylamine, N, N '
-Di-2-naphthyl-p-phenylenediamine, N-phenyl-N '-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, 2,6-di-t-butyl-4-ethyl Phenol, 2,2′-methylene-bis- (4-ethyl-6-butylphenol),
4,4'-butylidenebis (3-methyl-6-t-butylphenol), 2,5-di-t-amylhydroquinone, 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, 2-mercaptomethylbenzimidazole zinc Salt, nickel diethyldithiocarbamate, nickel dibutyldithiocarbamate, 1,
3-bis (dimethylaminopropyl) -2-thiourea,
Examples include tributylthiourea, tris (nonylphenyl) phosphite, dilauryl thiodipropionate, and special wax.

These antioxidants may be used alone or in combination of two or more as necessary. A high synergistic effect can be obtained by using a primary antioxidant and a secondary antioxidant in combination. These antioxidants are stable at the processing temperature, and it is important to appropriately select them in consideration of the reactivity with the magnetic powder, the resin, and other additives. The addition amount is suitably from 0.01 to 5% by weight based on the total amount of the magnetic powder and the binder. If the amount of the antioxidant exceeds 5%, it is not appropriate because the slip property in the molten state is reduced and the mechanical strength of the bonded magnet is remarkably reduced. When the amount is 0.01% or less, the antioxidant effect on the binder resin hardly appears.

In the present invention, a lubricant can be added for the purpose of reducing the melt viscosity and improving the injection moldability. Usable lubricants include waxes such as paraffin wax, liquid paraffin, polyethylene wax, ester wax, polyethylene wax, polypropylene wax, ketone wax, carnauba, micro wax, stearic acid, 12-oxystearic acid, lauric acid, capric acid Fatty acids such as zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, lithium stearate, strontium stearate, sodium stearate, potassium stearate, sodium oleate, zinc laurate, calcium laurate , Barium laurate, zinc linoleate, calcium linoleate,
Zinc 2-ethylhexoate, Lead benzoate, Para-tert-butyl zinc benzoate, Barium para-tert-butyl benzoate, Stearyl acid phosphite, Magnesium stearyl acid phosphite, Aluminum stearyl acid phosphite, Calcium stearyl acid phosphite, Zinc Metal soaps such as stearyl acid phosphite, barium stearyl acid phosphite, zinc behenyl acid phosphite, stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, hydroxystearic acid amide, ethylenebishydroxy Stearic acid amide, methylene bis stearic acid amide,
Ethylenebisstearic acid amide, ethylenebisisostearic acid amide, hexamethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N-N'-
Dioleyl adipamide, N, N'-dioleyl sebacamide, m-xylylene bisstearic acid amide, N, N'-diisostearyl isophthalic amide,
Ethylene bislauric amide, ethylene bisoleic amide, ethylene biscapric amide, ethylene biscaprylic amide, distearyl adipamide,
Dioleyl adipamide, N-stearyl stearamide, N-oleyl stearamide, N-stearyl erucamide, N-12 hydroxystearyl stearamide, N-12 hydroxystearyl oleamide, methylol stearamide, Fatty acid amides such as methylol behenamide, N-butyl-N'-stearyl urea, N-phenyl-N'-stearyl urea, N-stearyl-N'-stearyl urea, xylylene bisstearyl urea, toluylene bis stearyl urea Substituted ureas such as hexamethylene bisstearyl urea, diphenylmethane bisstearyl urea, diphenylmethane bis lauryl urea, cetyl 2-ethylhexanoate, methyl cocoate, methyl laurate, isopropyl myristate, Michin isopropyl, 2-ethylhexyl palmitate, palm fatty acid methyl, tallow fatty acid methyl, myristate octyldodecyl, methyl stearate, butyl stearate, stearic acid 2-
Ethylhexyl, isotridecyl stearate, methyl caprate, methyl methyl myristate, methyl oleate, isobutyl oleate, octyl oleate, lauryl oleate, oleyl oleate, myristyl myristate, hexyldecyl myristate, stearyl stearate, 2-oleate Fatty acid esters such as ethylhexyl, decyl oleate, octyldodecyl oleate, octyldodecyl behenate, behenyl behenate, octyldodecyl erucate, isobutyl oleate, sorbitan monostearate, sorbitan distearate,
Alcohols such as ethylene glycol, stearyl alcohol and behenyl alcohol; polyethers such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; polysiloxanes such as silicone oil and silicone grease;
Examples include fluorine compounds such as fluorine-based grease and fluorine-containing resin powder. One or two or more of these lubricants can be used. If the amount is too small, the effect of improving the fluidity is small, and if the amount is too large, the mechanical strength of the plastic magnet becomes extremely small, making it unsuitable for practical use. Therefore, the amount of addition is 0.1 to the total amount of the magnetic powder and the binder.
It is preferably from 0.01 to 5% by weight.

[0041]

EXAMPLE As for magnetic powder, 10 kg of Sm2Fe17N3 (average particle size by FSSS method, 3.0 μm), 860 g of hydroxymethyl methacrylate acid phosphate and stearyl phosphoric acid (100 wt. Of the phosphoric acid compound in an amount of 1 part by weight) and dissolved in 20 kg of pure water to obtain a phosphoric acid compound aqueous solution.

An aqueous solution of a phosphoric acid compound and 10 kg of magnetic powder are mixed and stirred for 30 minutes to separate the treated solution into solids and liquids. The solids are charged into a heating vessel capable of evacuating and dried in vacuum at 150 ° C. for 2 hours. After that, an oxidation treatment is performed by heating at 200 ° C. in the air for 2 hours.

The magnetic properties of the magnetic powder were determined by filling the magnetic powder into a sample case together with paraffin wax, melting the paraffin wax with a drier, aligning the axes of easy magnetization with an orientation magnetic field of 20 kOe, and subjecting the sample to pulse magnetization with a magnetization magnetic field of 40 kOe. Was measured for magnetic properties with a VSM (vibrating sample magnetometer) having a maximum magnetic field of 20 kOe. As a result of the measurement, σr = 1
It showed a value of 31 emu / g, iHc = 15.9 kOe.

The heat resistance of the obtained magnetic powder was 100%. Here, the heat resistance is determined by the coercive force iHc of the magnetic powder before heating when the magnetic powder is put in a heating vessel and heated at 250 ° C. for 30 minutes in the atmosphere.
It was defined as the percentage of the value divided by (0).

The rust-preventing property of the magnetic powder is as follows.
The state of rust generation after being placed in a 5% container and left for 20 days was visually observed and tested, and no rust was generated.

300 g of the obtained Sm2Fe17N3 magnetic powder
Then, 3 g of tetramethoxysilane and 1 g of water are added and mixed with a mixer. The mixture is heated at 200 ° C. in a vacuum to form a silicon oxide film on the particle surface. Next, 1.5 g of a silane coupling agent γ-aminopropyltriethoxysilane and 3.6 g of a liquid obtained by mixing ethanol and water at a ratio of 10: 1 are added by spraying, and mixed with a mixer for 1 minute in nitrogen gas. Next, the magnetic powder is taken out and subjected to a heat treatment at 90 ° C. for 30 minutes under reduced pressure to obtain a magnetic powder subjected to a coupling treatment. For 92 parts by weight of the magnetic powder subjected to the coupling treatment,
12 nylon as resin (A170 manufactured by Daicel Huls)
9P) and 3.0 parts by weight of copolymerized nylon (EMS
3.0 parts by weight of Japan Corporation (Grillon C) was added (resin ratio = 5: 5), and as an antioxidant,
0.5 parts by weight of N, N-bis {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl} hydrazine (manufactured by Ciba Geigy), and m-xylylene bisstearic acid amide as a lubricant. 0.5 parts by weight were added, and the mixture obtained by mixing for 5 minutes with a mixer was kneaded at 220 ° C. by a biaxial kneader to obtain compound pellets.

The obtained compound was subjected to an orientation magnetic field of 7 kO.
e, Injection molding while maintaining the temperature of the nozzle and the cylinder at 210 ° C. to form a 10φ × 7t axially-oriented, columnar bonded magnet molded body. The obtained bonded magnet molded body is
After magnetization with T, BH tracer (manufactured by Riken Denshi, BHU-60
20) As a result of measuring the VSM magnetic characteristics in Br), Br = 7.8
kG and iHc = 15.9 kOe. Also, 100
The initial demagnetization rate of the flux in the air at ℃ was 0.5%.

[0048]

As described above, according to the present invention,
The oxidation resistance, rust prevention and magnetic properties of the rare earth-iron-nitrogen based magnetic powder can be improved, and the magnetic properties of a plastic magnet using the same can be improved.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 8).
0 ° C heating)

FIG. 2 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 1).
00 ° C heating)

FIG. 3 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 1).
50 ℃ heating)

FIG. 4 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 2).
00 ° C heating)

FIG. 5 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 2).
50 ℃ heating)

FIG. 6 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 3).
00 ° C heating)

FIG. 7 is a characteristic diagram showing the relationship between coercive force and heating time (atmosphere 3).
20 ℃ heating)

FIG. 8 is a characteristic diagram showing a relationship between a coercive force and a heating temperature (O2:
N2 = 0: 100)

FIG. 9 is a characteristic diagram showing the relationship between coercive force and heating temperature (O2:
N2 = 5: 95)

FIG. 10 is a characteristic diagram (O) showing the relationship between coercive force and heating temperature.
2: N2 = 20: 80)

FIG. 11 is a characteristic diagram (O) showing the relationship between the coercive force and the heating temperature.
2: N2 = 50: 50)

FIG. 12 is a characteristic diagram (O) showing the relationship between the coercive force and the heating temperature.
2: N2 = 80: 20)

FIG. 13 is a characteristic diagram (O) showing the relationship between coercive force and heating temperature.
2: N2 = 100: 0)

FIG. 14 is a characteristic diagram showing the effect of drying conditions on coercive force and residual magnetization.

Continued on the front page F-term (reference) 4K018 AA27 AB10 BC12 BC28 KA46 4K026 AA02 AA23 BA08 BB10 CA16 CA26 DA03 DA11 DA15 EB11 5E040 AA03 AA19 BB04 BB05 BB06 BC01 CA01 HB11 HB14 NN05 NN17

Claims (3)

[Claims] 1. A rare earth-iron-nitrogen-based magnetic powder is mixed with P derived from phosphoric acid of a phosphoric acid-based compound in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the magnetic powder, and dried. A method for surface treating rare earth-iron-nitrogen based magnetic powder, comprising coating a particle surface with a phosphoric acid-based compound and then heating in a temperature range of 130 to 300 ° C in the air or in an atmosphere containing oxygen. 2. The method according to claim 1, wherein the aqueous solution of the phosphoric acid compound and the magnetic powder are mixed, and the solid content obtained by solid-liquid separation is charged into a heating vessel capable of evacuating and dried in a temperature range of 100 to 160 ° C. Item 4. The surface treatment method of rare earth-iron-nitrogen based magnetic powder according to item 1. 3. A rare earth-iron-nitrogen based magnetic powder obtained by the surface treatment method according to claim 1;
A plastic magnet, wherein at least one of a thermosetting resin, an elastomer, and a thermoplastic elastomer is mixed.