JP4300999B2 - Highly weather-resistant magnet powder, method for producing the same, and resin composition for rare earth bonded magnet using the same - Google Patents

Description

  The present invention relates to a highly weather-resistant magnet powder, a method for producing the same, and a resin composition for a rare earth bonded magnet using the same, and more particularly, when a magnetic alloy powder is pulverized, the surface is coated with a phosphate and organometallic compound coating. The present invention relates to a highly weather-resistant magnet powder capable of improving the weather resistance of a rare-earth bonded magnet by coating, a manufacturing method thereof, and a resin composition for a rare-earth bonded magnet using the same.

  In recent years, ferrite magnets, alnico magnets, rare earth magnets, and the like have been incorporated and used as motors in various products including general household electrical appliances, communication / acoustic equipment, medical equipment, and general industrial equipment. Although these magnets are mainly manufactured by a sintering method, they are fragile and difficult to be thinned, so it is difficult to mold them into complex shapes. Also, since they shrink by 15 to 20% during sintering, the dimensional accuracy cannot be increased. Post-processing such as polishing is required, and there are significant restrictions in terms of application.

  In contrast, bonded magnets (resin-bonded magnets) are thermosetting such as polyamide resins, thermoplastic resins such as polyphenylene sulfide resins, or epoxy resins, bis-maleimide triazine resins, unsaturated polyester resins, and vinyl ester resins. Since it can be easily manufactured by using a resin as a binder and filling it with magnet powder, new applications are being developed.

  When a bonded magnet is produced by kneading transition metal magnet alloy powder containing rare earth elements with a resin binder, a magnet is required to form a thin and complex shape into a bonded magnet with high strength and good dimensional accuracy. It is necessary to pulverize the alloy powder to about several μm to several tens of μm. Grinding is carried out in an inert gas or an organic solvent, but the magnet alloy powder after grinding is extremely active, and since it rapidly oxidizes when exposed to the air and deteriorates its magnetic properties, a slight amount of oxygen is inactivated after fine grinding. A method of introducing into an active atmosphere and gradual oxidation is employed.

  However, when a bonded magnet is produced from the magnetic alloy powder thus obtained and the time change of the coercive force of the magnet powder is examined, it remains relatively good at a decrease of about −2% after 24 hours under the condition of 80 ° C. drying. Under the condition of 80 ° C. and 90% RH, deterioration of −50% or more occurs after 24 hours. This is because the thermosetting resin is cured at 150 to 200 ° C. after injection molding or compression molding of the kneaded product of the resin binder and the magnet alloy powder at 200 to 300 ° C. in the bond magnet manufacturing process, so that the powder has a high temperature. Although it is considered that it is exposed to the atmosphere, even when only the powder is heated, the same deterioration cannot be avoided.

  On the other hand, the phosphate coating on the magnet alloy powder is said to improve heat resistance. After the magnet alloy powder is pulverized in an organic solvent, orthophosphoric acid is added in the absence of water to form a phosphate coating on the surface. Thus, a technique for improving the heat resistance of the magnet alloy powder has been proposed (see Patent Document 1).

Such a treatment can improve the heat resistance of the magnet alloy powder, but the coercive force decrease rate after being exposed to high temperature and high humidity of 60 to 80 ° C. and 80 to 95% RH for 24 hours is untreated powder. It was 40% or more of the same level and was not satisfactory.
The reason for this is that when phosphoric acid is added after pulverizing the magnet alloy powder, the reaction with the magnet alloy powder takes a short time of less than 2 minutes, so the water-insoluble phosphate coating formed on the surface is close to a monomolecular layer. It is considered that this is a very thin film of a phosphoric acid metal compound, and when the magnetic powder aggregates, the entire surface of the powder cannot always be completely protected.

Therefore, when a bonded magnet is formed using a magnet powder having a phosphate coating obtained by a conventional method, the aggregation of the magnet powder is released, and the metal surface not covered with phosphate is exposed, or the powder The film formed on the surface of the magnet powder may be damaged by rubbing.
Such a bonded magnet is easily affected by oxidation from a defect portion of the phosphate coating in a high humidity environment that is practically important. In particular, the magnet alloy powder showing a nucleation-type coercive force manifestation mechanism such as a samarium-iron-nitrogen alloy magnet has a problem that the coercive force is remarkably lowered when such a region is generated. It was.

  Therefore, it has been studied to coat the surface of the magnetic powder with an aluminum coupling agent, titanate coupling agent, etc., and the magnetic powder obtained by the surface treatment and a resin containing an unsaturated polyester resin and a vinyl ester resin A resin composition for resin-bonded magnets containing a binder as a main component has been proposed (see Patent Document 2). According to such a resin composition for a resin-bonded magnet, it is possible to obtain a magnet that is excellent not only in magnetic properties but also in shape flexibility, moldability, and mechanical strength.

  Also, prepare a solution for surface treatment in which a predetermined amount of phosphoric acid compound is dissolved in an alcoholic organic solvent, mix and stir this with magnetic powder, and then dry, and then dissolve a predetermined amount of alkoxysilane monomer in the organic solvent. It is described that the surface-coated magnet powder is obtained by the same treatment with the coating solution thus obtained (see Patent Document 3). According to such a resin composition for a resin-bonded magnet, since the alkoxysilane coupling agent is surface-coated on the phosphate compound, the magnetic properties are better than that of the phosphate compound alone, and the shape A resin-bonded magnet composition for rubber magnets having flexibility and excellent rust resistance, moldability, mechanical strength, flexibility, heat resistance and the like can be obtained.

As a result, it was confirmed that the phosphate compound and the coupling agent have equivalent functions as a surface coating treatment agent, but the weather resistance is sufficiently improved when exposed to a high temperature and high humidity environment for a long time of 300 hours or more. I couldn't say.
In recent years, bond magnets for small motors, acoustic equipment, and OA equipment have been strongly demanded for resin compositions for bond magnets that have excellent magnetic properties and a high degree of freedom in form of downsizing equipment. However, there are no conventional bonded magnets that satisfy both of these conditions, and the appearance of rare earth-iron-based magnet powders excellent in weather resistance and resistant to rusting, and bonded magnets using the same has been desired.
JP-A-4-21702 JP 2001-185411 A JP 2003-86410 A

  The object of the present invention is to further improve the weather resistance of rare earth-iron-based magnet powder used for rare earth bonded magnets in view of the above-mentioned problems of the prior art, and store the magnet powder for a long period of time at 80 ° C. and 90% RH. Another object of the present invention is to provide a highly weather-resistant magnet powder with little deterioration in coercive force, a method for producing the same, and a resin composition for a rare earth bonded magnet using the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor did not subject the rare earth-iron-based magnet alloy powder that had been pulverized to surface treatment with a phosphoric acid-based compound, but phosphoric acid-based materials. While pulverizing the magnet alloy powder in an organic solvent containing the compound, the surface of the pulverized magnet powder is coated with phosphate and an organometallic compound by having a specific coupling agent in addition to the phosphoric acid compound. As a result, a magnetic powder suitable for manufacturing a bonded magnet having good magnetic properties, flexibility in shape, and excellent rust resistance, formability, mechanical strength, flexibility, and heat resistance. As a result, the present invention was completed.

That is, according to the first invention of the present invention, in the method for producing a rare earth-iron-based magnet powder having a phosphate coating formed on the surface by a phosphate coating treatment, a phosphate compound is dissolved in an organic solvent. While the magnetic coarse powder is finely pulverized in the solution, the coupling agent is further added to the surface of the pulverized magnetic powder by adding a coupling agent represented by the general formula (1) to the solution. Hydrolyzed to form a phosphate film bonded to phosphate. At that time, the amount of phosphoric acid compound used is 0.1 to 2 mol / kg with respect to the weight of the magnet coarse powder, and the coupling agent is used. The amount is 0.05 to 5 wt% with respect to the weight of the magnet coarse powder, and the pH of the pulverized solution after the pulverization is allowed to stand is 4.0 or less. In an atmosphere of inert gas or vacuum, Process for producing a high weather resistance magnetic powder is provided, which comprises drying at a temperature of One 100 to 400 ° C..
R _(mn) -MX _(n) (1)
(In the formula, R is one or more organic groups having a hydrocarbon group or a functional group, X is a hydrolyzable group, M is any metal element selected from Si, Al, Ti, or Zr. When R contains two or more kinds of organic groups, the organic groups may be the same or different, m is the number of M bonds, and n is an integer of 2 to 4, and n is an integer of 1 to 4. Is shown.)

According to the second aspect of the present invention, in the method for producing a rare earth-iron-based magnet powder having a phosphate coating formed on the surface by a phosphate coating treatment, the phosphoric acid compound and the general formula (1) are used. By pulverizing the coarse magnet powder in a solution or dispersion in which the coupling agent is dissolved or dispersed together in an organic solvent, the coupling agent is hydrolyzed on the surface of the pulverized magnet powder. Then, a phosphate film bonded to the phosphate is formed. At that time, the amount of the phosphoric acid compound used is 0.1 to 2 mol / kg with respect to the weight of the magnet coarse powder, and the amount of the coupling agent used is , 0.05-5 wt% with respect to the weight of the magnet coarse powder, and the pH of the pulverized solution after pulverization is allowed to stand is 4.0 or less, and then the pulverized solution is made inert. 100 or 4 in an atmosphere of gas or vacuum Process for producing a high weather resistance magnetic powder is provided, which comprises drying at a temperature of 0 ° C..
R _(mn) -MX _(n) (1)
(In the formula, R is one or more organic groups having a hydrocarbon group or a functional group, X is a hydrolyzable group, M is any metal element selected from Si, Al, Ti, or Zr. When R contains two or more kinds of organic groups, the organic groups may be the same or different, m is the number of M bonds, and n is an integer of 2 to 4, and n is an integer of 1 to 4. Is shown.)

On the other hand, according to the third invention of the present invention, it is a highly weather-resistant magnet powder obtained by the production method of the first or second invention, and is a magnet when exposed to an environment of 80 ° C. and 90% RH for 300 hours. Provided is a highly weather-resistant magnet powder characterized in that the coercive force deterioration of the powder is 20% or less.

Moreover, according to 4th invention of this invention, the resin composition for rare earth bond magnets obtained by mixing the highly weather-resistant magnet powder of 3rd invention with a resin binder is provided.

  In the present invention, since the rare earth-iron-based magnet alloy powder is pulverized and simultaneously subjected to a surface treatment by the phosphoric acid compound and the coupling agent, no heat is generated even if the aggregate after pulverization / drying is crushed, Therefore, handling of the magnetic powder when kneading with the resin binder becomes easy. In addition, it can prevent deterioration of the magnetic properties due to oxidation and heat generation, so that the weather resistance of the magnet powder can be improved, and the weather resistance after molding into a bonded magnet using the magnet powder is also higher than when using the conventional powder. Therefore, it is possible to provide a bonded magnet having high weather resistance.

Hereinafter, the highly weather-resistant magnet powder of the present invention, its production method, and the resin composition for rare earth bonded magnets using the same will be described in detail.
The highly weather-resistant magnet powder of the present invention has a specific phosphate coating on the surface of a rare earth magnet such as a rare earth-iron-based magnet powder.

1. Magnet powder In the present invention, a rare earth-iron magnet powder such as a rare earth-cobalt, rare earth-iron-boron, rare earth-iron-nitrogen magnet powder, etc. can be used as a rare earth magnet as a raw material. Of these, rare earth-iron-nitrogen based magnet powder is preferred.

  As the rare earth elements, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy) , Holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

  On the other hand, iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn) are mentioned as an iron-type element, 1 type (s) or 2 or more types are selected from these groups. In addition to this, iron-based elements may contain any of Cr, V, or Cu.

In addition to the main component of the magnetic powder, those containing at least one element selected from B, Si, N, Zr, Al, or Ti are preferable. In addition, C, P, Ca, Zn, Ga, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Re, Os, Ir, Pt, or Au can be included. One or more selected from C, Al, Si, P, Ca, Ti, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Re, Os, Ir, Pt, or Au When the content is 7% by weight or less, the heat resistance of the magnetic powder can be improved.
Examples of rare earth elements include Sm, Nd, Pr, Y, La, Ce, Gd and the like, and they can be used alone or as a mixture. Among these, in particular, Sm or Nd is 5 to 40 at. %, Fe 50-90 at. % Content is preferred.

  The method for producing the rare earth-iron-based magnetic powder is not particularly limited and may be a reduction diffusion method, a melt casting method, a powder sintering method, or the like, but in the present invention, the reduction diffusion method is desirable.

Next, the process for producing a rare earth-iron magnet alloy by the reduction diffusion method will be described in detail.
(1) Reduction diffusion First, a rare earth oxide powder, a transition metal powder, and a reducing agent are blended to prepare a raw material mixture. If necessary, other raw material powders may be blended.

  The rare earth oxide powder is any one or more oxides of lanthanoid elements including Y, for example, at least one or more selected from the group of Y, La, Ce, Pr, Nd, and Sm. An oxide is mentioned. When at least one of these is combined with at least one oxide selected from the group consisting of Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb, the magnetic properties can be improved. In particular, when an oxide of Pr, Nd, or Sm is used, the magnetic properties of the magnet become extremely high. The rare earth element content in the rare earth-iron alloy is preferably 14 to 27 wt% from the viewpoint of magnetic properties.

  Examples of the transition metal powder include iron, cobalt, manganese, and nickel. Iron is preferable in terms of magnetic characteristics. Iron is an essential component of the rare earth-iron-based alloy powder, but a part thereof may be substituted with one or more of Co or Ni for the purpose of improving temperature characteristics and corrosion resistance without impairing magnetic characteristics. Although the thing of the particle size distribution close | similar to the particle size of a target product can be used, it is preferable that it is a particle size of 10-100 micrometers, for example. The transition metal powder used as a raw material is generally produced by an atomizing method, an electrolytic method, or the like.

  As the reducing agent, Li and / or Ca, or an alkali metal or alkaline earth metal element composed of at least one selected from these elements and Na, K, Rb, Cs, Mg, Sr, or Ba can be used. By containing 0.001 to 0.1 wt% of these alkali metal or alkaline earth metal elements in the crystal phase of the alloy powder, the time required for the nitriding treatment can be shortened. The particle size of the reducing agent is preferably 5 mm or less.

If the content of the alkali metal or alkaline earth metal element is less than 0.001 wt%, the treatment effect is small, and if it exceeds 0.1 wt%, the magnetic properties of the rare earth-iron-based magnet alloy, particularly the magnetization, is lowered, which is not preferable.
When these reducing agents are used, the input amount, the powder properties of the reducing agent and the rare earth oxide, the mixed state of various raw material powders, the temperature and time of the reduction diffusion reaction are carefully controlled. Among the reducing agents, metal Li or Ca is preferable in terms of handling safety and cost, and Ca is particularly preferable.

  Other raw material powders include Ti, V, Cr, Mn, Cu, Sb, Ge, Zr, Nb, Mo, Hf, Ta, W, Al, Si or C, and contain at least one of them. By doing so, the crystal structure is stabilized and the magnetic characteristics after nitriding can be improved. However, if the content is too large, the magnetic properties, particularly the saturation magnetization, is lowered, so that the content is preferably 12 wt% or less.

  The above rare earth oxide powder raw material, the transition metal powder raw material whose particle size is adjusted in the range of 10 to 100 μm, and other raw material powders are weighed and mixed, and further an amount sufficient to reduce the rare earth element After adding and mixing the reducing agent, the mixture is heated to a temperature above the temperature at which the reducing agent melts in a non-oxidizing atmosphere (an atmosphere in which oxygen is not substantially present), and the target rare earth-iron alloy is The temperature is raised to a temperature at which it does not melt, and is fired. This makes it possible to synthesize the rare earth-iron-based alloy in which the rare earth element diffuses into the transition metal using the exothermic temperature at the time of reduction while the rare earth oxide is reduced to the rare earth element.

  Since the melting point of Ca is 838 ° C. (boiling point is 1480 ° C.), the heat treatment is performed in a temperature range of about 1000 to 1200 ° C. and heated for 5 to 15 hours. Under these conditions, the reducing agent dissolves but does not become vapor, so that it can be processed efficiently.

(2) Nitriding treatment Next, the rare earth-iron alloy is cooled to room temperature. The reaction product (roasted product) containing the rare earth-iron alloy obtained by the reduction diffusion method can be subjected to hydrogen treatment under specific conditions after evacuation. The cooled roasted product is poured into pure water, and stirring and decantation are repeated until the hydrogen ion concentration (pH) becomes 10 or less. Then, acetic acid is added to water until the pH is about 5, and stirring is performed in this state. Thereafter, the obtained rare earth-iron alloy is dried to form a powder.

  In order to improve the nitriding rate of the rare earth-iron-based alloy powder, it is usually desirable to use particles of about 106 μm or less. In the nitriding treatment, the degree of nitriding differs depending on the size of the alloy powder (particles), and if a large particle having a particle size exceeding about 106 μm is used, nitriding does not proceed and the inside of the particle remains unnitrided and becomes magnetized. This is because sometimes the magnetization and coercive force are lowered. Therefore, when an undisintegrated lump remains in the rare earth-iron-based alloy powder, further pulverization is necessary. On the other hand, when the particle size is smaller than 30 μm, nitriding proceeds too much and the desired crystal phase breaks and becomes amorphous, and when magnetized, the coercive force is reduced, so that it is not crushed.

  The atmosphere for nitriding is an atmosphere containing nitrogen or ammonia, and ammonia is preferably used as a mixed gas with hydrogen. The mixing ratio of ammonia and hydrogen is not particularly limited, but is 10 to 70:30 to 90, preferably 30 to 60:40 to 70. Outside this range and too little ammonia, the efficiency of nitriding is reduced.

  The nitriding treatment is performed at a temperature of 300 to 650 ° C, preferably 350 to 600 ° C. If it is less than 300 ° C., it takes time for the nitriding reaction, and if it exceeds 650 ° C., the magnetic properties are affected, which is not preferable. The processing time required for nitriding is not particularly limited, but may be 5 to 10 hours.

2. Phosphoric acid compound Phosphoric acid compound is used for the surface treatment of the above-mentioned magnet powder, and heats and dries the finely pulverized magnet powder slurry to form a phosphate film. It is a compound that increases the binding strength with the binder and increases the weather resistance of the magnet powder.

Examples of phosphoric acid compounds include phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, linear polyphosphoric acid, and cyclic metaphosphoric acid.
In addition, ammonium phosphate, ammonium phosphate, etc., zinc phosphates that form hopites, phosphoferrites, etc. on the surface of magnet powder, zinc phosphates that form scholzeite, phosphophyllites, hopites, etc., manganese hulio Examples thereof include compounds that form films such as manganese phosphates that form light, iron heuriolite, etc., iron phosphates composed of strenite, hematite, and the like. The above phosphoric acid compound is usually mixed with a chelating agent, a neutralizing agent or the like to form a treating agent.

  In the present invention, a particularly preferred phosphoric acid compound is phosphoric acid. The reason why phosphoric acid is preferred is that the compatibility with the coupling agent is high, and the magnetic powder can be once dissolved by the acid component to reprecipitate the phosphoric acid compound film on the surface.

  The thickness of the phosphate coating formed on the surface of the magnet powder using the phosphoric acid compound is preferably 5 to 100 nm, and particularly preferably 8 to 80 nm. If the film thickness is less than 5 nm, a film may not be formed on a part of the powder. If the film thickness exceeds 100 nm, the density of the powder is lowered, and the magnetic properties and mechanical strength are lowered.

3. Coupling agent In the present invention, in order to form a phosphate coating on the surface of the magnet powder, a coupling agent is used during pulverization. The coupling agent is heated and dried after coating the magnet powder and fixed as a coating.

Any coupling agent may be used as long as it is represented by the following general formula (1).
R _(mn) -MX _(n) (1)
(In the formula, R is one or more organic groups having a hydrocarbon group or a functional group, X is a hydrolyzable group, M is any metal element selected from Si, Al, Ti, or Zr. When R contains two or more kinds of organic groups, the organic groups may be the same or different, m is the number of bonds of M, an integer of 2-4, and n is an integer of 1-4. Show.)

  Here, the hydrocarbon group is an alkyl group having 1 to 15 carbon atoms, an allyl group, or an aryl group, and these may be linear, branched, or cyclic. In addition, the functional organic group has a functional substituent in a part of the hydrocarbon group, and the substituent includes a vinyl group, a methacryloxy group, an epoxy group, a glycidoxy group, an amino group, a mercapto group. Etc. The structure of the organic group may be linear, branched or cyclic. On the other hand, the hydrolyzable group is an alkoxy group having 1 to 5 carbon atoms, a glycol group, or the like.

  A preferred hydrocarbon group is an alkyl group having 1 to 10 carbon atoms, and an organic group having functionality is a methacryloxy group, an epoxy group, a glycidoxy group, a functional substituent in a part of the hydrocarbon group, Those having an amino group are preferred. On the other hand, the hydrolyzable group preferably has an alkoxy group having 1 to 4 carbon atoms, and examples of the alkoxy group include methoxy, ethoxy and propoxy. It is preferable that m, which is the number of bonds of M, is 3 or 4, and n is 3 or 4.

  The coupling agent must contain any metal element of Si, Al, Ti, or Zr as an essential component, and at least one bond of the metal element must have a hydrolyzable group. Specific examples include those marketed as silane coupling agents, aluminum coupling agents, titanate coupling agents, and zirconate coupling agents.

Silane coupling agents include methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, heptyltrimethoxysilane, and n-decyltrimethoxysilane. , Vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyl Trimethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, benzyltrimethoxysilane, phenyltrimethoxysilane Lan, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, heptyltriethoxysilane, n-decyltriethoxysilane, phenyltriethoxysilane, Vinyltriethoxysilane, γ-methacryloxypropyltriethoxysilane, β- (3,4 epoxycyclohexyl) ethyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltriethoxysilane, N-β ( Aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane, γ-mercaptopropyltriethoxysilane, benzylto Trialkoxy silane such as tetraethoxysilane,
Dimethyldimethoxysilane, methylethyldimethoxysilane, methylpropyldimethoxysilane, methylbutyldimethoxysilane, ethylpropyldimethoxysilane, ethylbutyldimethoxysilane, diethyldimethoxysilane, ethylpropyldimethoxysilane, ethylbutyldimethoxysilane, ethylheptyldimethoxysilane, ethylhexyldimethoxy Silane, ethyloctyldimethoxysilane, dipropyldimethoxysilane, propylbutyldimethoxysilane, propylhexyldimethoxysilane, propylheptyldimethoxysilane, propyloctyldimethoxysilane, butylpentyldimethoxysilane, butylhexyldimethoxysilane, butylheptyldimethoxysilane, dihexyldimethoxysilane , Hexyl octyl Methoxysilane, hexyldecyldimethoxysilane, dioctyldimethoxysilane, diheptyldimethoxysilane, didecyldimethoxysilane, diphenyldimethoxysilane, divinyldimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylethyldimethoxysilane, γ -Methacryloxypropylbutyldimethoxysilane, β- (3,4 epoxycyclohexyl) ethylmethyldimethoxysilane, β- (3,4 epoxycyclohexyl) ethylpropyldimethoxysilane, β- (3,4 epoxycyclohexyl) ethylethyldimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylethyldimethoxysilane, γ-methacryloxypropylpropyldi Toxisilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylpropyldimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (Aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropylethyldimethoxysilane, N-β (aminoethyl) γ-aminopropylpropyldimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylethyldimethoxysilane, γ-aminopropylpropyldimethoxysilane, N-phenyl-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropylethyldimethoxysilane, N-phenyl-γ- Minopropylpropyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, benzylmethyldimethoxysilane, dimethyldiethoxysilane, methylethyldiethoxysilane, methylpropyldiethoxysilane, methylbutyldiethoxysilane, ethylpropyldiethoxysilane, ethylbutyl Diethoxysilane, diethyldiethoxysilane, ethylpropyldiethoxysilane, ethylbutyldiethoxysilane, ethylheptyldiethoxysilane, ethylhexyldiethoxysilane, ethyloctyldiethoxysilane, dipropyldiethoxysilane, propylbutyldiethoxysilane, Propylhexyldiethoxysilane, propylheptyldiethoxysilane, propyloctyldiethoxysilane, butylpentyldiethoxy Lan, butylhexyldiethoxysilane, butylheptyldiethoxysilane, dihexyldiethoxysilane, hexyloctyldiethoxysilane, hexyldecyldiethoxysilane, dioctyldiethoxysilane, diheptyldiethoxysilane, didecyldiethoxysilane, diphenyl Diethoxysilane, divinyldiethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylethyldiethoxysilane, γ-methacryloxypropylbutyldiethoxysilane, β- (3,4 epoxy cyclohexyl) ethylmethyl Diethoxysilane, β- (3,4-epoxycyclohexyl) ethylpropyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethylethyldiethoxysilane, γ-methacryloxyp Propylmethyldiethoxysilane, γ-methacryloxypropylethyldiethoxysilane, γ-methacryloxypropylpropyldiethoxysilane, γ-glycidoxymethyldiethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ- Glycidoxypropylethyldiethoxysilane, γ-glycidoxypropylpropyldiethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropylethyldiethoxy Silane, N-β (aminoethyl) γ-aminopropylpropyldiethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylethyldiethoxysilane, γ-aminopropylpropyldiethoxysilane, N-phenyl-γ -Aminopropylmethyl Dialkoxysilanes such as diethoxysilane, N-phenyl-γ-aminopropylethyldiethoxysilane, N-phenyl-γ-aminopropylpropyldiethoxysilane, γ-mercaptopropylmethyldiethoxysilane, benzylmethyldiethoxysilane, etc. ,
Trimethylmethoxysilane, dimethylethylmethoxysilane, dimethylpropylmethoxysilane, dimethylbutylmethoxysilane, diethylpropylmethoxysilane, diethylbutylmethoxysilane, triethylmethoxysilane, diethylpropylmethoxysilane, diethylbutylmethoxysilane, diethylheptylmethoxysilane, diethylhexyl Methoxysilane, diethyloctylmethoxysilane, tripropylmethoxysilane, dipropylbutylmethoxysilane, dipropylhexylmethoxysilane, dipropylheptylmethoxysilane, dipropyloctylmethoxysilane, dibutylpentylmethoxysilane, dibutylhexylmethoxysilane, dibutylheptylmethoxy Silane, trihexyl methoxysilane, dihexyl octyl Methoxysilane, dihexyldecylmethoxysilane, trioctylmethoxysilane, triheptylmethoxysilane, tridecylmethoxysilane, trivinylmethoxysilane, γ-methacryloxydipropylmethylmethoxysilane, γ-methacryloxypropyldiethylmethoxysilane, γ- Methacryloxypropyldibutylmethoxysilane, β- (3,4 epoxycyclohexyl) ethyldimethylmethoxysilane, β- (3,4epoxycyclohexyl) ethyldipropylmethoxysilane, β- (3,4 epoxycyclohexyl) ethyldiethylmethoxysilane, γ-methacryloxypropyldimethylmethoxysilane, γ-methacryloxypropyldiethylmethoxysilane, γ-methacryloxypropyldipropylmethoxysilane, γ-glycidoxy Cypropyldimethylmethoxysilane, γ-glycidoxypropyldiethylmethoxysilane, γ-glycidoxypropyldipropylmethoxysilane, N-β (aminoethyl) γ-aminopropyldimethylmethoxysilane, N-β (aminoethyl) γ -Aminopropyldiethylmethoxysilane, N-β (aminoethyl) γ-aminopropyldipropylmethoxysilane, γ-aminopropyldimethylmethoxysilane, γ-aminopropyldiethylmethoxysilane, γ-aminopropyldipropylmethoxysilane, N- Phenyl-γ-aminopropyldimethylmethoxysilane, N-phenyl-γ-aminopropyldiethylmethoxysilane, N-phenyl-γ-aminopropyldipropylmethoxysilane, γ-mercaptopropyldimethylmethoxysilane, benzine Dimethylmethoxysilane, trimethylethoxysilane, dimethylethylethoxysilane, dimethylpropylethoxysilane, dimethylbutylethoxysilane, diethylpropylethoxysilane, diethylbutylethoxysilane, triethylethoxysilane, diethylpropylethoxysilane, diethylbutylethoxysilane, diethylheptylethoxy Silane, diethylhexylethoxysilane, diethyloctylethoxysilane, tripropylethoxysilane, dipropylbutylethoxysilane, dipropylhexylethoxysilane, dipropylheptylethoxysilane, dipropyloctylethoxysilane, dibutylpentylethoxysilane, dibutylhexylethoxysilane , Dibutyl heptyl ethoxysilane, trihexyl ethoxy Silane, dihexyloctylethoxysilane, dihexyldecylethoxysilane, trioctylethoxysilane, triheptylethoxysilane, tridecylethoxysilane, trivinylethoxysilane, γ-methacryloxydipropylmethylethoxysilane, γ-methacryloxypropyldiethylethoxy Silane, γ-methacryloxypropyldibutylethoxysilane, β- (3,4 epoxycyclohexyl) ethyldimethylethoxysilane, β- (3,4 epoxycyclohexyl) ethyldipropylethoxysilane, β- (3,4 epoxycyclohexyl) ethyl Diethylethoxysilane, γ-methacryloxypropyldimethylethoxysilane, γ-methacryloxypropyl diethylethoxysilane, γ-methacryloxypropyldipropyl eth Xysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyldiethylethoxysilane, γ-glycidoxypropyldipropylethoxysilane, N-β (aminoethyl) γ-aminopropyldimethylethoxysilane, N- β (aminoethyl) γ-aminopropyldiethylethoxysilane, N-β (aminoethyl) γ-aminopropyldipropylethoxysilane, γ-aminopropyldimethylethoxysilane, γ-aminopropyldiethylethoxysilane, γ-aminopropyldi Propylethoxysilane, N-phenyl-γ-aminopropyldimethylethoxysilane, N-phenyl-γ-aminopropyldiethylethoxysilane, N-phenyl-γ-aminopropyldipropylethoxysilane, γ-mercaptopropyldimethyl Le silane, include such things alkoxysilane such as benzyl dimethyl ethoxy silane, the organic Shiranmonoma - may be used alone or in combination of two or more.

Preferred as the silane coupling agent is a trialkoxy silane having a linear alkyl group having 3 to 10 carbon atoms and a functional group having 1 to 4 carbon atoms. For example, γ-aminopropyltrimethoxysilane, phenyltrimethoxysilane, butyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, phenyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyl Dimethoxysilane, diphenyldimethoxysilane, γ-glycidoxymethyldiethoxysilane, diphenyldiethoxysilane and the like are preferable.
In addition to the above, hexamethyldisilazane and the like are known as silane coupling agents. However, such a silane coupling agent is not preferable because it does not have a hydrolyzable group.

Examples of the aluminum coupling agent include alkoxyaluminum chelates. Specific examples include acetoalkoxyaluminum diisopropylate.
The alkyl group of the aluminum coupling agent is linear or branched having 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms, and may contain a cyclohexyl ring, a vinyl group, or a phenyl group. Specific examples include acetoalkoxyaluminum diisopropylate and the like, and are marketed as “trade name: Preneact AL-M”. Aluminum-based coupling agents can be used alone or in combination of two or more.

  As titanate coupling agents, commercially available, for example, isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl) titanate, isopropyl tris (dioctyl pyrophosphate) titanate. Tetraisopropyl bis (dioctyl phosphite) titanate, tetraisopropyl titanate, tetrabutyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, Isopropyltridodecylbenzenesulfonyl titanate, isopropyltri (dioctylphosphate) titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyldimethacrylisostearoyl titanate, tetra (2, 2-di Ryloxymethyl-1-butyl) bis (ditridecyl phosphite) titanate, isopropyl tricumylphenyl titanate, bis (dioctylpyrophosphate) oxyacetate titanate, isopropylisostearoyl diacryl titanate -G

Of these, isopropyl triisostearoyl titanate is commercially available as “trade name: Preneact KRTTS”, and tetraoctylbis (ditridecylphosphite) titanate is commercially available as “trade name: Preneact KR46B” and can be easily obtained. .
Among these, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl triisostearoyl titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl phosphite) titanate. Especially preferred are bis (dioctylpyrophosphate) oxyacetate titanate. These titanate coupling agents can be used alone or in combination.

  Examples of the zirconate-based coupling agent include tetra-isopropyl zirconate, tetra-tertiary butyl zirconate, tetra-normal butyl zirconate, and derivatives thereof that are generally commercially available. These zirconate coupling agents can be used alone or in combination.

  Of the silane coupling agents, aluminum coupling agents, titanate coupling agents, and zirconate coupling agents, silane coupling agents are particularly preferable. These may be used alone or in combination with different types of coupling agents.

  The film thickness of the film made of phosphate formed on the magnet powder using the coupling agent is preferably 10 to 200 nm, particularly preferably 8 to 150 nm. If the film thickness is less than 10 nm, a film may not be formed on a part of the powder. If the film thickness exceeds 200 nm, the density of the powder decreases and the magnetic properties and mechanical strength decrease, which is not preferable.

4). Surface treatment method The highly weather-resistant magnet powder of the present invention is a surface treatment by adding a phosphoric acid compound and a specific coupling agent to an organic solvent when the rare earth-iron magnet alloy powder is pulverized by a pulverizer. It is manufactured by a method of heating and drying under specific conditions.

(1) Fine pulverization of coarse magnet powder The rare earth-iron-based magnet alloy coarse powder obtained by the reduction diffusion method or the like is put into a pulverized solution (phosphoric acid compound dissolved in an organic solvent). Finely pulverize using a pulverizer such as a bead mill or a medium stirring mill. A coupling agent is also added to the grinding solution.

  When an attritor is used, the magnet coarse powder is mixed with a grinding medium (diameter 2 to 10 mm) such as an iron ball in a grinding solution, and pulverized at a rotational peripheral speed of about 0.3 to 3.0 m / sec. . When using a medium stirring mill for fine pulverization, the diameter of the pulverization media (silicon nitride balls, zirconia balls, etc.) is about 0.3 to 3 mm, and the rotational peripheral speed is 5 to 50 m / sec. Just pulverize for a minute.

  There is no restriction | limiting in particular as an organic solvent, Usually, alcohols, such as ethanol or isopropyl alcohol, lower hydrocarbons, such as ketones and hexane, aromatics, such as toluene, or a mixture thereof is used. Of these, ethanol or isopropyl alcohol is particularly preferable.

In this step, when the rare earth-iron-based magnet powder is pulverized by a bead mill, a medium stirring mill or the like, a phosphoric acid compound and a coupling agent are present together with an organic solvent.
When a coupling agent is added while the rare earth-iron-based magnet alloy powder is pulverized with an attritor or the like in a pulverized solution containing a phosphoric acid compound and an organic solvent, even if a new surface is generated on the aggregated particles by pulverization, It reacts with a phosphoric acid compound and a coupling agent, and a film made of a stable phosphate is formed on the particle surface. Moreover, even if the pulverized magnet fine powder is then aggregated by the magnetic force, the contact surface is already stabilized, and corrosion does not occur due to crushing.

In the present invention, in order to present a phosphoric acid compound and a coupling agent in an organic solvent, phosphate-based compound and the coupling agent are both because eventually it becomes a predetermined concentration, during the grinding be added in one portion May be gradually added. The coupling agent may be added to the pulverized powder slurry immediately before pulverization. Furthermore, the order of addition is preferably that after adding the phosphoric acid compound and proceeding the pulverization, the coupling agent is added and the pulverization is continued.

  Although the usage-amount of a phosphoric acid type compound changes with the kinds and density | concentration, it shall be 0.1-2 mol / kg with respect to this magnet alloy powder weight. Furthermore, it is preferable to set it as 0.2-1.0 mol / kg. Thus, a phosphoric acid compound film having a thickness of about 5 to 100 nm can be formed on the magnet powder. When the addition amount is less than 0.1 mol / kg, the film is not sufficiently formed, and when it exceeds 2 mol / kg, the density of the magnet powder is lowered, and the magnetic properties and mechanical strength are lowered.

  The amount of the coupling agent used is preferably 0.05 to 5 wt% with respect to the weight of the magnet powder to be pulverized. If the amount is less than 0.05 wt%, sufficient surface treatment cannot be performed, and oxidation occurs and heat is generated while being taken out into the atmosphere and dried. On the other hand, if the content is 5 wt% or more, unreacted magnetic powder remains, and the remainder reduces the density of the bonded magnet, resulting in a decrease in magnetic properties, which is not preferable.

By making a phosphoric acid compound and a coupling agent present in the pulverized solution at the time of pulverization, these react with the elements constituting the magnet, such as rare earth elements and iron dissolved during pulverization, and are coated on the magnet powder as phosphates. . Although the phosphate film is formed in a short time, this reaction is completed, and in order to form a phosphate film having a sufficient film thickness, depending on the type of the phosphoric acid compound, the coupling agent, etc., 30 to Crushing and stirring for 180 minutes, preferably 60 to 150 minutes are required.
After completion of the pulverization and coating of the present invention, it is preferable to measure the pH in a state where the pulverized solution is allowed to stand in order to confirm whether the phosphoric acid coating has been performed normally. In that case, the pH is preferably 4.0 or less. If it exceeds 4.0, the amount of phosphoric acid added is insufficient or the stirring capacity of the pulverizer is insufficient, so that phosphoric acid is not uniformly distributed to the pulverized powder, and the coating is performed uniformly. There is a possibility that it is not.

  In the present invention, instead of subjecting the magnet powder that has been pulverized to surface treatment as conventionally performed, an organic solvent containing a phosphoric acid compound is mixed with the rare earth-iron-based magnet alloy powder and pulverized. In the meantime, the surface of the magnetic powder is coated by adding a specific coupling agent, but the reason for adopting this method is that after adding the phosphoric acid compound after pulverizing the magnetic alloy powder, A phosphate coating that is insoluble in water is formed on the surface of the magnet alloy powder, but since the reaction takes a short time of less than 2 minutes, it is a very thin film of a phosphate metal compound close to a monomolecular layer. This is because the entire surface of the powder cannot be completely protected.

When a bonded magnet is formed using a magnet powder having a phosphate coating obtained by a conventional method, the magnet powder is agglomerated and the metal surface not covered with phosphate is exposed or the powder is rubbed. As a result, the film formed on the surface of the magnet powder is damaged.
Such a bonded magnet is easily affected by oxidation from a defect portion of the phosphate coating in a high humidity environment that is practically important. In particular, in a magnetic alloy powder showing a nucleation-type coercive force generation mechanism such as a samarium-iron-nitrogen alloy magnet, the coercive force tends to be remarkably lowered when such a region occurs in part. .

  According to the present invention, by using an appropriate amount of a phosphoric acid compound and the above-mentioned coupling agent at the time of pulverization of the magnetic powder, a coating made of phosphate with a mechanochemical effect on the surface of the magnetic powder while suppressing aggregation of the magnetic powder. No special conditions other than the presence of an inert gas or vacuum in the drying after the surface treatment are possible, and the drying time can be shortened and obtained. Even if the magnetic powder is exposed to an environment of 80 ° C. and 90% RH for 300 hours or more, the coercive force is hardly deteriorated and the weather resistance can be greatly improved.

  The mechanism by which the weather resistance of the obtained magnet powder is improved when the phosphoric acid compound and the coupling agent are present simultaneously during the pulverization of the magnet powder is not clear, but generally the wettability to the magnet powder is higher than that of the phosphoric acid compound. It can be presumed that the phosphoric acid compound was uniformly dispersed and reacted with the surface of the magnet powder to which an excellent coupling agent was bonded to form a denser phosphate film. In addition, it is considered that the coupling agent is hydrolyzed and bonded to the phosphate coating (the surface of the magnetic powder) by the acid component and water molecules generated at the stage where the phosphate coating is formed. It is presumed that a magnetic powder having excellent weather resistance is obtained by a chain reaction of this phosphate film formation reaction and coupling reaction.

(3) Heat-drying In the present invention, as described above, during the pulverization of the rare earth-iron-based magnet alloy coarse powder, it is coated with a phosphoric acid compound and a coupling agent, and then magnet fine powder (pulverized slurry) Is heated and dried, and uniformly fixed on the surface as a stable phosphate coating.
That is, the pulverized slurry composed of the magnetic alloy fine powder and the organic solvent is filtered to separate the organic solvent, if necessary, and then supplied to a drying apparatus, and heated to a specific temperature and dried in a specific atmosphere.

  When the atmosphere is heated, if the atmosphere gas contains a large amount of oxygen, the finely magnetized magnet may be burned. Therefore, a vacuum or an inert gas such as nitrogen or argon is used as the atmosphere gas. It is preferable. In consideration of production cost, it is particularly preferable to use argon or nitrogen, and the oxygen concentration in the atmospheric gas is preferably 5% or less, more preferably 3% or less.

  The heating temperature needs to be 100 ° C. or higher, preferably 100 to 400 ° C. A more preferable temperature is 150 ° C to 250 ° C. When the temperature is lower than 100 ° C., the drying does not proceed sufficiently and the formation of a stable surface film is inhibited. On the other hand, if the temperature exceeds 400 ° C., the coercive force is considerably lowered because of thermal damage to the magnet powder. Therefore, it is important to perform heat treatment within the above range in order to obtain a highly weather-resistant magnet powder.

The drying device (dryer) is not particularly limited, and a spray-drying device can be used in addition to a stirring-type dryer in which the slurry is heated under reduced pressure while stirring, a stationary electric furnace, and the like.
In the case of a spray-drying apparatus, an apparatus composed of a main body having a cylindrical body at the top and an inverted conical shape at the bottom, a cyclone disposed downstream thereof, a bag filter, and the like is preferable. A disk-shaped rotating body (atomizer) for receiving the pulverized slurry is placed on the top plate at the upper part of the main body, and a pipe for introducing a heated air current is connected to the outer periphery of the atomizer. Further, downstream of the bag filter, a heat exchanger (economizer) for cooling the heated airflow and utilizing waste heat, a heat medium cooler, and the like are installed.

In the drying apparatus, first, a heated air stream heated by an electric heater is supplied from a pipe to an atomizer at the upper part of the main body.
The heated airflow passes through the filter and the electric heater and is introduced into the drying device, and becomes atmospheric gas in the main body. Nitrogen or an inert gas is preferably used as the heating airflow, and nitrogen is particularly preferable in consideration of production costs. The air volume of the heated air flow varies depending on the size of the apparatus main body, the processing amount of the pulverized slurry, etc., but is, for example, 50 to 200 Nm ³ / h, preferably 70 to 150 Nm ³ / h.

  Next, the atomizer is rotated by a motor, and pulverized slurry is supplied from the pump into the atomizer from the top of the main body. When the slurry falls on the atomizer, it is ejected into the hot air of the heated airflow from the gap formed on the side surface of the atomizer, and is heated and dried by the hot air while being dispersed. The dried magnet powder collides with the inner wall of the apparatus main body, and aggregation is released by the impact. The fallen fine powder is collected by a cyclone, and the vaporized solvent is cooled by a condenser and collected as a liquid.

  The rotational peripheral speed of the atomizer (disk) depends on the type, size and other conditions of the apparatus, but is preferably 30 m / sec or more, particularly 30 to 70 m / sec. If it is less than 30 m / sec, a sufficient dispersion force cannot be applied to the magnet powder, so that the deaggregation effect is not improved and drying is insufficient, which is not preferable. On the other hand, even if the rotational peripheral speed exceeds 70 m / sec, there is no significant change in the dispersion state, and depending on the apparatus, it becomes difficult to perform steady operation by approaching the capacity limit.

  In the agitation type dryer conventionally used for drying the pulverized slurry, the magnet powder is pressed against the side wall of the apparatus and becomes easy to be fixed, so post-processing is required. The phosphates on the surface may come into contact and aggregate. However, if the slurry is sprayed using a spray-type dryer having an atomizer, the magnet powder can be completely dried, and thereafter, even if the powder comes into contact with each other, the conventional fixation and aggregation do not occur.

  By the way, in the conventional gradual oxidation method, since it was necessary to carefully introduce a small amount of oxygen at the time of drying in order to prevent oxidation of the magnet powder, it was necessary to take a long time for drying. This has also been a factor in increasing manufacturing costs. In addition, when the time-dependent change in the magnetic properties of the obtained magnetic powder is examined, a relatively large coercive force is maintained in an environment at 80 ° C. in a dry state, but only 24 hours in an environment at 80 ° C. and 90% RH. The coercive force was degraded by about 60% when left untreated.

  On the other hand, in the present invention, since an appropriate amount of a phosphoric acid compound and a coupling agent are present in the organic solvent at the time of pulverization, a surface film can be formed on the surface of the magnet powder with a mechanochemical effect while suppressing aggregation of the magnet powder, Other than using an inert gas or vacuum as the drying atmosphere, no special conditions are required, and the drying time can be shortened. Further, the coercive force of the obtained powder hardly deteriorates even when exposed to an environment of 80 ° C. and 90% RH for 300 hours, and not only has good weather resistance as a powder, but also mixed with a resin. If a bonded magnet is manufactured, extremely high coercive force is exhibited.

Surface particle size distribution of the magnet powder are uniformly coated with phosphate film, the cumulative volume percent particle diameter _{D 50} of 1 to 5 [mu] m, in particular 2-4 [mu] m, and _(D 20 _{-D 70)} particle diameter width, i.e. grain radial width of the cumulative volume percent particle diameter D ₂₀ and D ₇₀ is 5μm or less, preferably becomes 4μm or less, the particle size distribution does not change even after subsequent drying process.

When the average particle size D ₅₀ is less than 1 μm, aggregation cannot be suppressed. On the other hand, when it exceeds 5 μm, not only the magnetic properties are deteriorated, but also the moldability is deteriorated when the bond magnet is formed. Moreover, it is not preferable that the particle size distribution (D ₂₀ -D ₇₀ ) particle size width exceeds 5 μm because aggregation cannot be suppressed.

  The rare earth-iron-based magnet powder of the present invention is uniformly coated with a phosphate coating, and its dispersibility is high and aggregation is suppressed. It becomes possible to manufacture a bonded magnet having high (Br), squareness (Hk), and coercive force (iHc). The magnet powder has excellent magnetic properties such as a residual magnetic flux density of 1.3 T (13 kG) or more, a squareness of 480 kA / m (6 kOe) or more, and a coercive force of 800 kA / m (10 kOe) or more.

5. Resin binder In the present invention, the resin binder used in the production of the resin composition for rare earth bonded magnet is not particularly limited as long as it functions as a binder for magnetic powder, and is a thermosetting resin binder. Alternatively, a thermoplastic resin binder is used.

The type of the thermosetting resin is not particularly limited as long as it is cured in the mold during molding and serves as a binder for the magnetic powder.
Examples thereof include at least one resin selected from the group consisting of unsaturated polyester resins having radical polymerization reactivity, vinyl ester resins, urethane (meth) acrylate resins, and polyester (meth) acrylate resins.

  The unsaturated polyester resin is a radically polymerizable heat comprising an unsaturated polyester obtained by a polycondensation reaction between a polyhydric alcohol and a saturated polybasic acid and / or an unsaturated polybasic acid, and a monomer copolymerizable with the ester. A general term for curable resins.

Here, the polyhydric alcohol is not particularly limited, and examples thereof include hydrogenated bisphenol A, hydrogenated bisphenol F, bisphenol A propylene oxide adduct, bisphenol F propylene oxide adduct, and hydrogenated bisphenol S. Ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,6-hexanediol, dibromoneopentyl glycol, pentaerythritol diallyl ether, allyl glycidyl ether, etc. Can be mentioned.
These polyhydric alcohols may be used alone or in combination of two or more. In the present invention, those containing a polyhydric alcohol having a bisphenol skeleton, hydrogenated bisphenol A, hydrogenated bisphenol F or the like in at least a part of the molecular structure are more preferred.

  Saturated polybasic acids include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, adipic acid, sebacic acid, het acid, tetrabromophthalic anhydride, etc. Can be mentioned.

  Examples of the unsaturated polybasic acid include maleic anhydride, fumaric acid, itaconic acid and the like, but are not particularly limited. These dibasic acids may be used alone or in combination of two or more.

The vinyl ester resin can be obtained, for example, by addition reaction of an epoxy compound and an unsaturated monobasic acid.
The epoxy compound used as a raw material for the vinyl ester resin is not particularly limited as long as it is a compound having at least one epoxy group in the molecule.
Specifically, for example, an epibis type glycidyl ether type epoxy resin obtained by a condensation reaction of bisphenols such as bisphenol A and bisphenol S and epihalohydrin; phenol, cresol, novolak which is a condensate of bisphenol and formalin; Novolac type glycidyl ether type epoxy resin obtained by condensation reaction with epihalohydrin; glycidyl ester type epoxy resin obtained by condensation reaction of tetrahydrophthalic acid, hexahydrophthalic acid, benzoic acid and epihalohydrin; Glycidyl ether type epoxy resin obtained by condensation reaction with amine; Amine-containing glycidyl obtained by condensation reaction of hydantoin or cyanuric acid with epihalohydrin Ether type epoxy resins.
Moreover, the compound which has an epoxy group in a molecule | numerator by addition reaction with these epoxy resins, polybasic acids, and / or bisphenols may be sufficient. Only one kind of these epoxy compounds may be used, or two or more kinds may be appropriately mixed.

  In the present invention, among these, those containing at least polyhydric alcohol having a bisphenol skeleton, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like are more preferable.

  Although it does not specifically limit as unsaturated monobasic acid, Specifically, acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, etc. are mentioned. Moreover, you may use half esters, such as maleic acid and itaconic acid. Furthermore, these compounds are combined with polyvalent carboxylic acids such as fumaric acid, itaconic acid and citraconic acid, saturated monovalent carboxylic acids such as acetic acid, propionic acid, lauric acid and palmitic acid, and saturated polyvalent carboxylic acids such as phthalic acid. You may use together an acid or its anhydride, and compounds, such as a saturated or unsaturated alkyd whose terminal group is a carboxyl group. These unsaturated monobasic acids may use only 1 type and may mix 2 or more types suitably.

  The urethane (meth) acrylate resin is not particularly limited. For example, after reacting a polyisocyanate with a polyhydroxy compound or a polyhydric alcohol, a hydroxyl group-containing (meth) acrylic compound and, if necessary, Accordingly, it can be obtained by reacting a hydroxyl group-containing allyl ether compound. Moreover, after reacting a hydroxyl group-containing (meth) acrylic compound with a polyhydric 551-roxy compound or a polyhydric alcohol, a polyisocyanate may be further reacted.

  Specifically, the polyisocyanate used as a raw material for the urethane (meth) acrylate resin is 2,4-tolylene diisocyanate and its isomer, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene. Examples include diisocyanate, dicyclohexylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate.

  The polyhydric alcohols used as raw materials for the urethane (meth) acrylate resin are specifically ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 2-methyl. -1,3-propanediol, 1,3-butanediol, adducts of bisphenol A and propylene oxide or ethylene oxide, 1,2,3,4-tetrahydroxybutane, glycerin, trimethylolpropane, 1,3-propane Diol, 1,2-cyclohexane glycol, 1,3-cyclohexane glycol, 1,4-cyclohexane glycol, para-xylene glycol, bicyclohexyl-4,4′-diol, 2,6-de Ring recall, 2,7-decalin glycol, and the like, but not particularly limited. Only one kind of these polyhydric alcohols may be used, or two or more kinds may be appropriately mixed.

Furthermore, examples of the polyhydroxy compound used as a raw material for the urethane (meth) acrylate resin include polyester polyol and polyether polyol.
Specifically, glycerin ethylene oxide adduct, glycerin propylene oxide adduct, glycerin tetrahydrofuran adduct, glycerin ethylene oxide propylene oxide adduct, trimethylolpropane ethylene oxide adduct, trimethylolpropane propylene oxide adduct, trimethylolpropane tetrahydrofuran adduct, Trimethylolpropane ethylene oxide propylene oxide adduct, pentaerythritol ethylene oxide adduct, pentaerythritol propylene oxide adduct, pentaerythritol tetrahydrofuran adduct, pentaerythritol ethylene oxide propylene oxide adduct, dipentaerythritol ethylene oxide adduct, dipentaerythritol propylene oxide adduct Dipentaerythritol tetrahydrofuran adduct, but dipentaerythritol ethylene oxide-propylene oxide adducts, and the like, are not particularly limited. Only one kind of these polyhydroxy compounds may be used, or two or more kinds may be appropriately mixed.

  The hydroxyl group-containing (meth) acrylic compound used as a raw material for the urethane (meth) acrylate resin is not particularly limited, but is preferably a hydroxyl group-containing (meth) acrylic ester, specifically 2-hydroxyethyl (meth) acrylate. , 2-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, di (meth) acrylate of tris (hydroxyethyl) isocyanuric acid, penta Examples include erythritol tri (meth) acrylate. Only one kind of these hydroxyl group-containing (meth) acrylic compounds may be used, or two or more kinds may be appropriately mixed.

  Specific examples of the hydroxyl group-containing allyl ether compound used as a raw material for the urethane (meth) acrylate resin include ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, triethylene glycol monoallyl ether, and polyethylene glycol monoallyl. Ether, propylene glycol monoallyl ether, dipropylene glycol monoallyl ether, tripropylene glycol monoallyl ether, polypropylene glycol monoallyl ether, 1,2-butylene glycol monoallyl ether, 1,3-butylene glycol monoallyl ether, hexylene Glycol monoallyl ether, octylene glycol monoallyl ether, trimethylolpropane diallyl ether, glyceride Nji allyl ethers, pentaerythritol triallyl ether, and the like, but is not particularly limited. Only one kind of these hydroxyl group-containing allyl ether compounds may be used, or two or more kinds may be appropriately mixed.

  Furthermore, the polyester (meth) acrylate resin is not particularly limited, and can be obtained, for example, by reacting a (meth) acrylic compound with an end of an unsaturated or saturated polyester. As a raw material of polyester, the same compound as the compound illustrated as a raw material of unsaturated polyester resin can be used, for example. As the (meth) acrylic compound used as a raw material for the polyester (meth) acrylate resin, in addition to the unsaturated monobasic acid such as (meth) acrylic acid, the same compound as the raw material for the urethane (meth) acrylate resin may be used. it can.

In addition, as the polyester (meth) acrylate resin, oligomers based on polyfunctional acrylic acid esters and methacrylic acid esters can be used without any particular limitation.
Specific examples include alkyl-modified dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. For oligomers based on polyfunctional acrylic acid esters and methacrylic acid esters used, see There is a detailed description in the publication “UV / EB Curing Handbook-Raw Materials” (pages 11 to 66).

These unsaturated polyester resins, vinyl ester resins, urethane (meth) acrylate resins, and polyester (meth) acrylate resins can be blended with a copolymerizable monomer.
Examples of the copolymerizable monomer include (I) vinyl monomers such as styrene, vinyl toluene, α-methyl styrene, methyl methacrylate, vinyl acetate, (II) diallyl phthalate, diallyl maleate, diallyl isophthalate, diallyl. Allyl monomers such as terephthalate, triallyl isophthalate, triallyl isocyanurate, diallyl tetrabromophthalate, (III) acrylics such as phenoxyethyl acrylate, 1,6-hexanediol acrylate, trimethylpropane triacrylate, 2-hydroxyethyl acrylate Examples include acid esters. These copolymerizable monomers may be used alone or in combination of two or more, and the amount of the monomer added is not particularly limited.
The shape of the resin is not particularly limited, such as powder, beads, pellets, etc., but a powder that can be uniformly mixed with the magnetic powder is desirable.

  Among these, unsaturated polyester resin or vinyl ester resin is preferable. Although not limited by the degree of polymerization or the molecular weight, a resin that is liquid at a temperature of 150 ° C. or lower and has a viscosity at 25 ° C. of 5000 mPa · s or lower is preferable from the viewpoint of moldability.

The organic peroxide is generally a curing agent that is blended in a thermosetting resin having radical polymerization reactivity and initiates the reaction of the thermosetting resin raw material.
Examples of the organic peroxide include (I) ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, and acetyl seton peroxide. Oxides, (II) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4 -Peroxyketals such as bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, (III) t-butylhydroperoxide, cumene hydroperoxide, di-isopropylbenzene Hydro Hydroperoxides such as -oxide, menthane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, (IV) di-t -Butyl peroxide, t-butyl cumyl peroxide, di-cumyl peroxide, α, α'-bis (t-butylperoxy-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butyl Peroxy) hexane, dialkyl peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, (V) acetyl peroxide, isobutyl peroxide, octanonyl peroxide, deca Noyl peroxide, Lauroyl peroxide, 3,5,5-trimethyl Diacyl peroxides such as xanoyl peroxide, succinic acid peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, toluoyl peroxide, (VI) di-isopropyl peroxydicarbonate, di-2-ethylhexyl Peroxydicarbonate, di-n-propylperoxydicarbonate, bis- (4-tert-butylcyclohexyl) peroxydicarbonate, di-myristylperoxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di -Peroxydicarbonates such as methoxyisopropylperoxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, diallylperoxydicarbonate, (VII) t-butylperoxyacetate , T-butylperoxyisobutyrate, t-butylperoxypivalate, t-butylperoxyneodecanoate, cumylperoxyneodecanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy -3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoyl) Peroxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, cumylperoxyoctoate, t-hexylperoxyneodecanoate, t-hexylperoxypivalate, t-butylpero Xineohexanoate, t-hexylperoxyneohexanoate, cumylpe Carboxy peroxy esters and the like Neo hexanoate, (VIII) acetyl cyclohexyl sulfonyl Lupe Loki side, t- butyl Perot carboxymethyl allyl carbonate.

The amount of these organic peroxides to be added varies depending on the dilution rate and the amount of active oxygen, and thus cannot be specified in general, but is preferably 0.05 to 10 parts by weight with respect to 100 parts by weight of the thermosetting resin.
The organic peroxide can be used singly or in a mixed system of two or more, but in order to ensure a longer pot life of the finally obtained resin-bonded magnet composition, a peroxyketal system is used. It is very preferable to use any one of dialkyl peroxides alone.

  In order to increase the pot life during storage of the resin-bonded magnet composition, an N-oxyl compound can be added. N-oxyls are nitrogen-containing cyclic compounds such as 5-membered pyrrolidine compounds and 6-membered piperidine compounds.

  In the system containing the magnetic powder as in the present invention, not only the redox reaction but also a complicated reaction with a thermosetting resin having a radical polymerization reactivity or styrene occurs in combination with this, and the acceleration effect is extremely high. In addition, the pot life is significantly shorter than that of a normal transition metal simple substance composition. When an N-oxyl compound is added to such a composition containing a magnetic powder, a radical curing agent, and a thermosetting resin, it functions extremely effectively in suppressing the effect of such special reaction, and the pot life is reduced. Can be long.

  As a 5-membered ring pyrrolidine compound, the molecular chain end of the compound is represented by the following general formula (2):

In formula (2), X ₁ and X ₂ each independently represent a hydrogen atom, —OR ₅ group, —OCOR ₆ group or —NR ₇ R ₈ group, and R ₁ , R ₂ , R ₃ , R ₄ Each independently represents an alkyl group having 1 or more carbon atoms, and R ₅ , R ₆ , R ₇ and R ₈ are each independently a compound represented by a hydrogen atom or an alkyl group having 1 to 16 carbon atoms. .

  As a 6-membered piperidine compound, the end of the molecular chain of the compound is represented by the following general formula (3):

In the above formula (3), X ₃ , X ₄ and X ₅ each independently represent a hydrogen atom, —OR ₁₃ group, —OCOR ₁₄ group or —NR ₁₅ R ₁₆ group, and R ₉ , R ₁₀ , R ₁₁ and R ₁₂ each independently represents an alkyl group having 1 or more carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms), and R ₁₃ , R ₁₄ , R ₁₅ and R ₁₆ are each independently hydrogen. A compound represented by an atom or an alkyl group having 1 to 16 carbon atoms (preferably an alkyl group having 1 to 12 carbon atoms).

  Further, as the N-oxyl compound, in addition to the above, the molecular chain terminal is represented by the following general formula (4):

However, in the formula (4), R ₁₇ and R ₁₈ may each independently be a compound having a structure represented by an alkyl group having 4 or more carbon atoms.

As the N-oxyls, a 6-membered piperidine compound represented by the formula (3) is preferable.
For example, di-t-butylnitroxyl, 1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol, 1-oxyl- 2,2,6,6-tetramethylpiperidin-4-yl-acetate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate, 1-oxyl-2 , 2,6,6-tetramethylpiperidin-4-yl-stearate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-4-t-butylbenzoate, bis (1-oxyl) -2,2,6,6-tetramethylpiperidin-4-yl) succinic acid ester, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipic acid ester Bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butyl Malonic acid ester, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) Isophthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexa Hydroterephthalate, N, N′-bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide, N- (1-oxyl-2,2,6,6-teto Methylpiperidin-4-yl) caprolactam, N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) dodecylsuccinimide, 2,4,6-tris-N-butyl-N- Examples include (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) -s-triazine, but are not particularly limited. Only one kind of these N-oxyls may be used, or two or more kinds may be appropriately mixed.

Among these, in the above formula (3), X ₃ , X ₄ , and X ₅ each independently represent a hydrogen atom, —OH group, —COOH group, —OCOR ₁₄ group, or —NH ₂ group, R ₉ , R ₁₀ , R ₁₁ , R ₁₂ are each an N-oxyl compound having a structure in which each independently represents an alkyl group having 1 to 3 carbon atoms, and R ₁₄ is an alkyl group having 1 to 10 carbon atoms. is there.

  Such compounds include 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl or bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate Is mentioned. 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl can be represented by the following general formula (5).

General formula (5)

  These N-oxyls compounds are those having a reactivity with an alkyl radical and further reacting with a peroxy radical among the stabilizers, or having a reactivity with an alkyl radical after reacting with a peroxy radical. Is preferred. By such a reaction, it is considered that the pot life of the resin composition can be secured longer. A representative example of a compound having reactivity with a peroxy radical after reaction with an alkyl radical is 2,2,6,6-tetramethyl-4-hydroxypiperidine-1- represented by the general formula (4). It is oxyl.

  The amount of the N-oxyl compound added varies depending on the type and cannot be defined uniformly, but is 0.1 to 10 parts by weight, preferably 0.1 to 100 parts by weight of the thermosetting resin. 3 to 5 parts by weight. If the amount added is less than 0.1 parts by weight, sufficient pot life cannot be secured. On the other hand, when the amount is more than 10 parts by weight, it is not desirable because the density of the molded body is reduced and the surface is roughened.

  Resin binders include phenol, polymerization inhibitor, low shrinkage agent, reactive resin, reactive diluent, unreactive diluent, modifier, thickener, lubricant, depending on the application of the resin bonded magnet. Release agents, UV absorbers, flame retardants, stabilizers, inorganic fillers, pigments, and the like can be added.

  In general, in the case of a thermosetting resin having radical polymerizability, a polymerization inhibitor is added for the purpose of increasing the viscosity during storage of the resin itself, delaying gelation and maintaining a long storage period. There is no particular problem even if the polymerization inhibitor is added to ensure long-term storage.

Furthermore, a low shrinkage agent can be added for the purpose of suppressing curing shrinkage during radical polymerization curing.
The low shrinkage agent is a resin capable of preventing shrinkage during molding or preventing the reinforcing agent from floating on the surface of the molded product. For example, a polymerizable monomer solution of acrylic and styrene resins, thermoplastic nylon, polyethylene Resin powder, polyvinyl chloride resin powder, three-dimensional acrylic resin powder and styrene resin powder. These 1 type (s) or 2 or more types can be mixed and used. Since excessively adding a low shrinkage agent often causes a decrease in strength, it is 0.1 to 75 parts by weight, more preferably 0.5 to 50 parts by weight with respect to 100 parts by weight of the thermosetting resin. .

  On the other hand, examples of the thermoplastic resin binder include 6 nylon, 66 nylon, 11 nylon, 12 nylon, 612 nylon, aromatic nylon, polymerized fatty acid polyamide block copolymer, and polymerized fatty acid polyetheresteramide block copolymer. Polymers, polyamide resins such as modified nylon partially modified or copolymerized with these molecules, linear polyphenylene sulfide resin, crosslinked polyphenylene sulfide resin, semi-crosslinked polyphenylene sulfide resin, low density polyethylene, linear low Density polyethylene resin, high density polyethylene resin, ultra high molecular weight polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, ionomer resin, polymethylpentene resin, police Resin resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyvinyl formal resin, methacrylic resin, polyvinyl fluoride Vinylidene fluoride resin, poly (trifluoroethylene chloride) resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, ethylene-tetrafluoroethylene copolymer resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, polytetra Fluoroethylene resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene oxide resin, polyallyl ether allyl sulfone tree , Polyether sulfone resin, polyether ether ketone resin, polyarylate resin, aromatic polyester resin, cellulose acetate resin, the above-mentioned resin-based elastomers, etc., random copolymerization with these monopolymers and other monomers Examples thereof include a polymer, a block copolymer, a graft copolymer, and a terminal group-modified product with another substance.

  Among these, 11 nylon, 12 nylon and their modified nylon, nylon elastomer, polymerized fatty acid based polyamide block copolymer, or polymerized fatty acid based polypolymer are used because of various properties of the obtained molded product and ease of production thereof. The use of an ether ester amide block copolymer is preferred. It is naturally possible to blend two or more of these thermoplastic resins.

  The melt viscosity and molecular weight of these thermoplastic resins are desirably lower within a range where desired mechanical strength can be obtained, and although depending on other conditions, the number average molecular weight is 100,000 or less, particularly 50,000 or less. Preferably there is. Although the shape as a raw material is not particularly limited, such as powder, beads, pellets, etc., powder form is desirable in view of uniform mixing with magnetic powder.

6). Rare earth bonded magnet composition The rare earth bonded magnet composition of the present invention is obtained by mixing the resin binder with the above-mentioned rare earth-iron-based magnet powder with improved weather resistance.

(1) Mixing of resin binder In order to produce a composition for a rare earth bonded magnet, a rare earth magnet powder is mixed with a resin binder and kneaded.
As the rare earth magnet powder, not only anisotropic magnet powder but also isotropic magnet powder is targeted, but it is preferable to use magnet powder having an anisotropic magnetic field (HA) of 4000 kA / m (50 kOe) or more. The rare earth-iron-based magnetic powder preferably has an average particle diameter of 1 to 100 μm from the viewpoint of the melt fluidity of the obtained bonded magnet resin composition, the orientation of the magnetic powder, the filling rate, and the like. The average particle size is preferably 1 to 50 μm, and more preferably 1 to 10 μm.

  The rare earth-iron-based magnet powder may be mixed with various magnet powders that are usually raw materials for bonded magnets, such as ferrite magnet powder and alnico magnet powder, in accordance with the required magnetic properties. Although not only anisotropic magnets but also isotropic magnet powders can be mixed, it is preferable to use magnet powders having an anisotropic magnetic field (HA) of 4.0 MA / m (50 kOe) or more. A magnet powder containing 30% by weight or more, particularly 50% by weight or more of a magnet powder having a particle size of 100 μm or less is preferable.

  The blending amount of the resin binder is not particularly limited, but is 1 to 50 parts by weight, preferably 3 to 50 parts by weight with respect to 100 parts by weight of the bonded magnet resin composition. Furthermore, 5 to 30 parts by weight, particularly 7 to 20 parts by weight is more preferable. If the resin binder is less than 1 part by weight, not only will the kneading torque increase and fluidity will be lowered, making the molding difficult, but the magnetic properties will be insufficient. Since characteristics cannot be obtained, it is not preferable.

What is necessary is just to melt-knead this resin composition for bond magnets, after mix | blending the following additives and fillers with the resin composition for bond magnets as needed.
A resin-bound magnet composition in which a resin binder and additives are blended with magnetic powder is mixed by a known method. The mixing method is not particularly limited. For example, a blender such as a ribbon blender, a tumbler, a nauter mixer, a Henschel mixer, a super mixer, a planetary mixer, or a banbury mixer, a kneader, a roll, a kneader ruder, a single screw extruder, two A kneader such as a screw extruder is used. In the case of a thermosetting resin, it is preferable to use a mixer having a low shearing force and a cooling function so that curing does not proceed due to shearing heat generated during mixing.

(Additive)
The bonded magnet resin composition includes a reactive diluent, an unreactive diluent, a thickener, a lubricant, a mold release agent, an ultraviolet absorber, a flame retardant, and various other stabilizers as long as the object of the present invention is not impaired. An agent or the like can be blended.

Examples of the reactive diluent include styrene, fatty acid diglycidyl ether, ethylene glycol glycidyl ether, phenyl glycidyl ether, and glycerin polyglycidyl ether.
Examples of the unreactive diluent include alcohols such as ethanol and isopropanol.

Examples of the thickener include beryllium oxide, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and zinc oxide.
Examples of the lubricant include waxes such as paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, and micro wax, stearic acid, 1,2-oxystearic acid, lauric acid, palmitic acid, oleic acid, and the like. Fatty acids such as fatty acids, calcium stearate, barium stearate, magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate, zinc 2-ethylhexoate (metal soaps) ), Stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, lauric acid amide, hydroxystearic acid amide, methylene bis-stear Fatty acid amides such as acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, distearyl adipic acid amide, ethylene bis oleic acid amide, dioleyl adipic acid amide, N-stearyl stearic acid amide, butyl stearate, etc. Fatty acid esters, alcohols such as ethylene glycol and stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethers made from these modified products, polysiloxanes such as dimethylpolysiloxane and silicon grease, fluorine-based oils Fluorine compounds such as 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.
The blending amount of the lubricant is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the magnetic powder.
Examples of the mold release agent include zinc stearate and a system in which this is mixed with other metal stearates.

Examples of the ultraviolet absorber include benzophenone series such as phenyl salicylate, p-tert-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 3-2′-dihydroxy-4-methoxybenzophenone; 2 Benzotriazoles such as-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ', 5'-ditert-butylphenyl) benzotriazole; oxalic anilide derivatives and the like It is done.
Examples of the flame retardant include antimony trioxide, sodium antimonate, organic bromine compounds, chlorinated paraffin, and chlorinated polyethylene.

As stabilizers, 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-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-butyl In addition to hindered amine stabilizers such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, phenolic, phosphite, thioether antioxidants, etc. One or more of these can be used.
The compounding amount of the stabilizer is usually 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight with respect to the total amount of the magnetic powder.

These additives are appropriately selected according to the type of thermoplastic resin binder and the type of magnetic powder, and the amount of the additive is not particularly limited, but is usually 100 parts by weight of the resin composition for bonded magnets. On the other hand, the total amount is preferably 0.1 to 20 parts by weight, particularly preferably 0.1 to 3 parts by weight.
Although the shape of the resin composition for bond magnets can be in the form of powder, beads, pellets, or a mixture thereof, a pellet (or lump) is desirable from the viewpoint of ease of handling.

(filler)
In the present invention, a filler having a large reinforcing effect such as mica, whisker, talc, carbon fiber, or glass fiber can be appropriately added to the bonded magnet resin composition as long as the object of the present invention is not hindered. . That is, when the magnetic properties required for the bonded magnet are relatively low and the amount of magnetic powder filled is relatively small, the mechanical strength of the bonded magnet tends to be low. In such a case, in order to supplement the mechanical strength Fillers such as mica and whiskers can be added.
The type and blending amount of these fillers are not particularly limited and may be appropriately selected according to the required properties of the bond magnet.

The bonded magnet resin composition can produce a bonded magnet by any of an injection molding method, a compression molding method, an extrusion molding method, an injection compression molding method, an injection press molding method, a transfer molding method, or a rolling molding method. Among these, a preferable molding method is an injection molding method.
For injection molding, after adding 7.5 to 11 wt% of a resin binder to 89.0 to 92.5 wt% of rare earth-iron-based magnet powder, a biaxial kneader or the like is used at 200 to 250 ° C. Knead. Thereafter, a resin composition (pellet) for a rare earth bonded magnet having a diameter of, for example, about 5 mm × 5 mm is produced by a hot cut pelletizer or the like.
If a rare earth-iron-nitrogen alloy powder is used as a magnet powder and the surface is treated with a pulverized solution containing a phosphoric acid compound and a coupling agent, the resin binder can be highly filled at a rate of 90% by weight or more. A bonded magnet having excellent high weather resistance can be obtained.

  Hereinafter, although an example and a comparative example are given and explained concretely, the present invention is not limited at all by these examples.

Highly weather-resistant magnet powder was produced using the following materials.
A Magnetic powder (Sm—Fe—N-based magnetic powder: substantially magnetic coarse powder of Sm ₂ Fe ₁₇ N ₃ produced using the following reduction diffusion method, average particle size of 100 μm or more)

1.53 kg of electrolytic iron with a purity of 99.9% and a particle size of about 50 μm or less, 0.75 kg of samarium oxide powder (Sm ₂ O ₃ ) with a purity of 99% and an average particle size of 43 μm, and granular metallic calcium with a purity of 95.0% 0.3 kg was mixed using a V blender.
The obtained mixture was put into a cylindrical stainless steel container and subjected to heat treatment at 950 ° C. for 8 hours under an argon gas atmosphere. Next, the roasted product was cooled and poured into pure water in a beaker, and stirring and decantation were repeated until the hydrogen ion concentration pH became 10 or less. Acetic acid was added to water until the pH was 5 (hereinafter referred to as “acidic aqueous solution pH value”), and the mixture was stirred for 10 minutes in this state. Stirring was performed by rotating a glass screw with a motor. Finally, moisture was removed and dried to obtain an alloy powder.
Next, the inside of the furnace is set to a pure nitrogen atmosphere with a flow rate of 100 ml / min, the above alloy powder is placed in the soaking part, the temperature is increased to 485 ° C. at a rate of temperature increase of 10 ° C./min, and maintained for 24 hours. A powder was obtained.

B Surface treatment agent-Phosphoric acid compound 85% phosphoric acid aqueous solution (trade name Phosphoric acid, manufactured by Kanto Chemical Co., Inc.)
・ Silane coupling agent
γ-aminopropyltrimethoxysilane (manufactured by Nihon Unicar Company, also referred to as silane 1)
Vinyltriethoxysilane (manufactured by Nihon Unicar Company, also referred to as silane 2)
・ Titanate coupling agents
Isopropyltris (dioctyl pyrophosphate) titanate
(Ajinomoto Co., also referred to as titanate 1)

The characteristics and performance of the magnetic alloy powder obtained in the experiment were measured and evaluated by the following methods.
(1) Observation of coating and analysis of coating composition The phosphate coating formed on the surface of the obtained magnet powder was observed with FE-TEM (field emission transmission electron microscope), and the coating composition was EDX (energy dispersive X). Line spectroscopy analyzer).
(2) Weather resistance of magnet powder The magnet powder was exposed to a constant temperature and humidity chamber at 80 ° C. and 90% RH for 300 hours, and then the magnetic properties (coercivity) of the magnet powder were measured to evaluate the weather resistance.
(3) Magnetic property evaluation The magnetic property (coercive force) of the sample was measured at room temperature with a thiophye self-recording magnetometer.

Example 1
10 kg of the magnetic alloy coarse powder obtained by the reduction diffusion method was charged into a medium stirring mill containing 4 kg of φ0.5 mm silicon nitride balls and 10 kg of ethanol (solvent). After adding 0.3 mol / kg of 85% phosphoric acid aqueous solution to 1 kg of alloy powder in the solvent and grinding for 1 hour, 0.2 wt% of γ-aminopropyltrimethoxysilane was further added to the above pulverized product. Milled for another 30 minutes. The medium stirring mill was operated at a rotational peripheral speed of 10 m / sec to finely pulverize the magnet alloy. Thereafter, the pH was measured while the pulverized solution was allowed to stand.
After fine pulverization, the pulverized slurry was heated from room temperature to 150 ° C. in vacuum and then dried for 1 hour to obtain magnet powder. The thickness of the coating was 3-5 μm.
This powder did not generate heat even when taken out into the atmosphere, and the coercive force deterioration was 18% from the result after 300 hours of the weather resistance test. The results are shown in Tables 1 and 2.

(Example 2)
In the same manner as in Example 1, after pulverizing phosphoric acid in ethanol containing 0.3 mol / kg based on the weight of the magnet powder, 0.2 wt% γ-aminopropyltrimethoxysilane was further added to the pulverized product. And then pulverized and heat-treated at 150 ° C. for 1 hour in argon.
After the weather resistance test, almost no change in coercive force was observed.

(Example 3)
After the magnet powder was pulverized under the same conditions as in Example 2, the heat treatment was performed at 150 ° C. in nitrogen for 1 hour. After the weather resistance test, almost no change in coercive force was observed.

(Example 4)
After the magnet powder was pulverized under the same conditions as in Example 2, the heat treatment was performed in nitrogen at 200 ° C. for 1 hour. After the weather resistance test, almost no change in coercive force was observed.
In heat treatment, it is inevitable that very small amounts of oxygen and moisture are present in nitrogen, and when the same magnetic powder is used, the coercive force after 1 hour is usually less likely to deteriorate at 150 ° C. than at 200 ° C. . However, since the formed film is denser and stronger at 200 ° C., it is considered that the coercive force after 300 hours does not change.

(Example 5)
It was produced in the same manner as in Example 2 except that it was pulverized in ethanol containing 0.4 mol / kg of phosphoric acid with respect to the magnet powder weight, and heat-treated at 150 ° C. for 1 hour in argon gas. After the weather resistance test, almost no change in coercive force was observed.

(Example 6)
Heat treatment was performed in argon gas at 150 ° C. for 1 hour in the same manner as in Example 2 except that phosphoric acid was pulverized in ethanol containing 0.2 mol / kg of magnet powder weight. After the weather resistance test, no change in coercive force was observed.

(Example 7)
In place of the silane monomer of the coupling agent, isopropyl tris (dioctyl pyrophosphate) titanate was 0.2 wt% with respect to the weight of the magnet powder, and heat treatment was performed at 130 ° C. as in Example 2. It was manufactured by the method. After the weather resistance test, almost no change in coercive force was observed.

(Example 8)
Instead of the coupling agent silane monomer, vinyltriethoxysilane was made 0.2 wt% with respect to the weight of the magnet powder, and the heat treatment was carried out at 130 ° C. in the same manner as in Example 2. After the weather resistance test, almost no change in coercive force was observed.

Example 9
While pulverizing the magnet powder in ethanol containing 0.3 mol / kg of phosphoric acid with respect to the weight of the magnet powder, 5 wt% of 0.2 wt% γ-aminopropyltrimethoxysilane in the pH range of 3.4 to 3.7 was obtained. The powder was pulverized while being added in portions, and dried in vacuum at 150 ° C. to obtain magnet powder.
This powder did not generate heat even when taken out into the atmosphere, and the result after 300 hours of the weather resistance test was a coercive force deterioration of 15%.

(Example 10)
Magnet powder is pulverized in a solvent in which 0.2 wt% of γ-aminopropyltrimethoxysilane is previously added and dissolved in ethanol containing 0.3 mol / kg of phosphoric acid with respect to the weight of the magnet powder. The temperature was raised to 150 ° C. and dried for 1 hour to obtain magnet powder.
The powder did not generate heat even when taken out into the atmosphere, and the coercive force deterioration was 20% from the result after 300 hours of the weather resistance test.

(Comparative Example 1)
The magnet powder was pulverized in ethanol containing no phosphoric acid and then dried in vacuum at room temperature. When this magnet powder was taken out into the atmosphere, oxidation progressed and heat was generated. The coercive force was not measured because it was demagnetized due to oxidation.

(Comparative Example 2)
The magnet powder was pulverized in ethanol containing 0.1 mol / kg of phosphoric acid with respect to the magnet powder weight, and then dried in vacuum at room temperature. When this magnet powder was taken out into the atmosphere, oxidation progressed and heat was generated. The coercive force was not measured because it was made nonmagnetic.

(Comparative Example 3)
After magnet powder was pulverized in ethanol, oxygen was gradually introduced and dried in vacuum at room temperature. The coercive force deteriorated to 71% after the weather resistance test.

(Comparative Example 4)
An attempt was made to pulverize the magnetic powder in ethanol containing 2.1 mol / kg of phosphoric acid with respect to the weight of the magnetic powder.

(Comparative Example 5)
The magnet powder was pulverized in ethanol containing 0.3 mol / kg of phosphoric acid with respect to the weight of the magnet powder, and then dried at 300 ° C. in vacuum. The coercive force hardly changed over time before and after the weather resistance test, but the initial coercive force itself was small.

(Comparative Example 6)
After pulverizing the magnet powder in ethanol, phosphoric acid was added at 0.3 mol / kg based on the weight of the magnet powder, and the mixture was stirred and dried at room temperature in a vacuum. The coercive force deterioration after the moisture resistance test was 30%.

(Comparative Example 7)
After the magnet powder was pulverized in ethanol containing no phosphoric acid as in Comparative Example 1, 0.2 wt% γ-aminopropyltrimethoxysilane was added to the pulverized product, and the pulverized product was uniformly stirred. And coated with magnetic powder. Then, it was dried at room temperature in vacuum. As a moisture resistance test, the sample was exposed to a constant temperature and humidity chamber of 80 ° C. × 90% RH, but could not be evaluated due to heat generation in 1 hour.

In Examples 1 to 10, since the surface treatment was carried out while pulverizing the magnet coarse powder in the presence of a phosphoric acid compound and a coupling agent, a stable phosphate coating can be formed, and it can be maintained even if exposed to high temperature and high humidity for a long time. The magnetic force hardly decreased.
However, in Comparative Examples 1 to 7, since the surface treatment was performed on the magnetic coarse powder under the condition that neither the phosphoric acid compound or the coupling agent was present or any of them, a good phosphate coating could not be formed. When exposed to high temperature and high humidity for a long time, the coercive force significantly decreased.

Claims (4)

In a method for producing a rare earth-iron-based magnet powder having a phosphate coating formed on a surface thereof by a phosphate coating treatment,
While pulverizing the coarse magnet powder in a solution in which a phosphoric acid compound was dissolved in an organic solvent, the powder was further pulverized by adding a coupling agent represented by the general formula (1) to the solution. The coupling agent is hydrolyzed on the surface of the magnet powder to form a phosphate film in which the phosphate is bonded to the phosphate, and the amount of the phosphoric acid compound used is 0.1 to 0.1% of the weight of the magnet coarse powder. 2 mol / kg, the amount of the coupling agent used is 0.05 to 5 wt% with respect to the weight of the magnet coarse powder, and the pH in a state where the pulverized solution after pulverization is allowed to stand is 4.0. A method for producing a highly weather-resistant magnet powder, characterized in that the pulverized solution is dried in an inert gas or vacuum atmosphere at a temperature of 100 to 400 ° C.
R _(mn) -MX _(n) (1)
(In the formula, R is one or more organic groups having a hydrocarbon group or a functional group, X is a hydrolyzable group, M is any metal element selected from Si, Al, Ti, or Zr. When R contains two or more kinds of organic groups, the organic groups may be the same or different, m is the number of M bonds, and n is an integer of 2 to 4, and n is an integer of 1 to 4. Is shown.) In a method for producing a rare earth-iron-based magnet powder having a phosphate coating formed on a surface thereof by a phosphate coating treatment,
The magnet is pulverized by finely pulverizing the coarse magnet powder in a solution or dispersion in which the phosphoric acid compound and the coupling agent represented by the general formula (1) are dissolved or dispersed in an organic solvent. On the surface of the powder, the coupling agent is hydrolyzed to form a phosphate film in which the phosphate is bonded to the phosphate. At this time, the amount of the phosphoric acid compound used is 0.1 to 2 mol / wt based on the weight of the magnet coarse powder. kg, and the amount of the coupling agent used is 0.05 to 5 wt% with respect to the weight of the magnet coarse powder, and the pH in a state where the pulverized solution is allowed to stand after pulverization is 4.0 or less. A method for producing a highly weather-resistant magnet powder, characterized in that the ground solution is then dried under an atmosphere of an inert gas or vacuum and at a temperature of 100 to 400 ° C.
R _(mn) -MX _(n) (1)
(In the formula, R is one or more organic groups having a hydrocarbon group or a functional group, X is a hydrolyzable group, M is any metal element selected from Si, Al, Ti, or Zr. When R contains two or more kinds of organic groups, the organic groups may be the same or different, m is the number of M bonds, and n is an integer of 2 to 4, and n is an integer of 1 to 4. Is shown.) The highly weatherable magnet powder obtained by the production method according to claim 1 or 2 , wherein the coercive force deterioration of the magnet powder when exposed to an environment of 80 ° C and 90% RH for 300 hours is 20% or less. Highly weather-resistant magnet powder characterized by A resin composition for a rare earth bonded magnet obtained by mixing the highly weather-resistant magnet powder according to claim 3 with a resin binder.