JP2011052277A - Rare-earth-iron-based magnet powder for bond magnet and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rare-earth-iron-based magnet powder for a bond magnet, which is superior in the moldability of a composition prepared from the powder for the bond magnet, and in mechanical strength of the bond magnet, and to provide a production method therefor. <P>SOLUTION: The rare-earth-iron-based magnet powder has a film containing Fe, P, O and RE (RE is a rare earth element) with a film thickness of 100 nm or less on its surface. The amount of Fe which exists in the film in a metallic state is 2.0% or less when the amount is determined by measuring Fe2p<SB>3/2</SB>spectrum on the surface of the magnet powder with an X-ray photoelectron spectroscopy apparatus and then calculating the amount based on the area of the obtained spectrum profile. The film is formed by bringing the magnet powder into contact with a treatment liquid containing phosphoric acid, and then heating and drying the wet film at a particular temperature. The amount of Fe in the metallic state is reduced by the operation of repeating the treatment of contacting phosphoric acid and the heating and drying treatment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rare earth-iron-based magnet powder for bonded magnets and a method for producing the same, and more particularly, a rare earth-iron-based magnet for bonded magnets having excellent formability and mechanical strength of bonded magnets when used as a bonded magnet composition. The present invention relates to a powder and a manufacturing method thereof.

  In recent years, ferrite magnets, alnico magnets, rare earth magnets, and the like have been incorporated and used as motors and sensors 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 thermoplastic resins such as polyamide resins and polyphenylene sulfide resins, or epoxy resins, bis-maleimide triazine resins, unsaturated polyester resins, vinyl esters when used in combination with curing agents. Since thermosetting resins such as resins are used as binders and can be easily manufactured by filling them with magnet powder, new applications are being developed.

  Among such bonded magnets, in particular, a bonded magnet using an iron-based magnet powder containing a rare earth element has a large load on the kneader when producing a composition obtained by mixing and kneading a magnet powder and a resin binder. Viscosity may increase. For this reason, when such a composition is to be molded by an injection molding method, an extrusion molding method, a compression molding method, or the like, the moldability is poor and it is difficult to obtain a good molded product. This is mainly because the binder resin is denatured by the catalytic action of the magnet powder, and can be mitigated by subjecting the magnetic powder to various surface treatments.

  As the surface treatment, for the purpose of preventing rust in a conventional high temperature and high humidity environment, for example, by forming a coating film such as a thermosetting resin on the surface of the molded body, rusting is suppressed, or the surface of the molded body It has been proposed to suppress rusting by applying a coating treatment with a phosphate-containing paint (for example, see Patent Document 1).

  As for the surface treatment on the powder surface, chemical conversion treatment such as phosphate treatment or chromate treatment is performed (for example, see Patent Document 2), and a polymer film is formed (for example, see Patent Document 3). Furthermore, techniques such as metal plating (see, for example, Patent Document 4) have also been proposed.

  Such a surface treatment also has an effect of suppressing not only rusting but also resin modification. However, in order to obtain a sufficient effect by forming a film, it is necessary to make the film thickness about several tens of μm. With such a thick film, the volume fraction of the material that exhibits magnetic characteristics decreases, and the magnetic characteristics Will be reduced. In addition, in the above method, since fine powders also aggregate when forming a film, it is difficult to align the direction of easy magnetization in the case of anisotropic magnet powder, and the magnetic properties of the magnet compact It was inevitable that there was a decline.

  Conventionally, when magnet powder is coated to a film thickness of nm level, a method of adding phosphoric acid to the grinding solvent and grinding the magnet powder to produce rare earth and iron phosphates on the powder surface has been studied. (For example, refer to Patent Document 5). According to this method, the film thickness of the magnet powder to be produced is small, so the decrease in magnetic properties and agglomeration of the fine powder due to the nonmagnetic phase are alleviated, but the effect of suppressing the denaturation of the binder resin is not sufficient, and the composition In some cases, the fluidity and viscosity of the product changed, and the moldability was still impaired. Furthermore, stress concentration due to thermal strain during molding and insufficient affinity with the binder resin overlap with the interface with the binder resin, resulting in problems such as low mechanical strength of the molded body as a bond magnet and destruction during processing. It was.

  In recent years, in the manufacture of motors for home appliances, automobile sensors and motors, it is necessary to transport by ship to assemble parts overseas, and the use environment and transport environment become more severe, and the size of the equipment has been reduced. There has been a demand for magnet powder that can solve the problems and has excellent magnetic properties.

JP 2000-208321 A Japanese Patent Laid-Open No. 1-14902 JP-A-4-257202 Japanese Patent Laid-Open No. 7-142246 JP 2002-124406 A

  The object of the present invention is to provide a rare earth-iron-based magnet powder for bonded magnets and a method for producing the same, which is excellent in formability and mechanical strength of bonded magnets when used as a bonded magnet composition in view of the above-mentioned problems of the prior art. There is to do.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that a rare earth element-iron-based magnet powder having a film containing Fe, P, O, RE (RE is a rare earth element) having a film thickness of 100 nm or less. In this case, by reducing the amount of iron Fe present as a metal state on the powder surface to a specific value or less, when this magnet powder is used as a bonded magnet composition, the moldability is excellent and the obtained molding is obtained. It was found that the mechanical strength of the product can be improved. In order to obtain such a magnet powder, a solution containing phosphoric acid and a rare earth-iron-based magnet powder are brought into contact with each other, followed by heat treatment in a temperature range of 100 to 300 ° C. in a non-oxidizing atmosphere. The present rare earth-iron-based magnet powder was again brought into contact with a solution containing phosphoric acid, and then found to be efficiently manufactured by heat treatment in a non-oxidizing atmosphere at a temperature range of 80 to 200 ° C., thereby completing the present invention. It came to do.

That is, according to the first aspect of the present invention, in the rare earth element-iron-based magnet powder having a coating film containing Fe, P, O, RE (RE is a rare earth element) having a film thickness of 100 nm or less on the surface, When the amount of Fe present in the metal state is calculated based on the area of the spectrum profile obtained after measuring the Fe2p _3/2 spectrum on the surface of the magnet powder with an X-ray photoelectron spectrometer, it is 2.0% or less. There is provided a rare earth-iron-based magnet powder for bonded magnets.

Further, according to the second invention of the present invention, in the first invention, the amount of Fe present in the metal state in the coating is first measured by the X-ray photoelectron spectrometer, and the binding energy is 705 eV to 720 eV. The base line of the Fe2p _3/2 spectrum profile obtained in the range is set by the Shirley method, the waveform P1 of iron Fe in the metal state, the waveform P2 of the iron Fe oxide form, another oxide of iron Fe The waveform P3 is divided into three waveforms, and then the areas of the respective waveforms P1, P2, and P3 are calculated, and the waveform area of the waveform P1 of the iron Fe in the metal state with respect to the sum of these three waveform areas A rare earth-iron-based magnet powder for bonded magnets is provided which is characterized in that it is determined as a percentage of
According to the third invention of the present invention, in the first invention, the rare earth-iron-based magnet powder is NdFeB-based, Sm ₂ (Co, Fe, Cu, M) _17- based, or SmFeN-based. A rare earth-iron-based magnet powder for bonded magnets is provided. Note that M in the Sm ₂ (Co, Fe, Cu, M) ₁₇ system corresponds to any element of Mn, Zr, or Hf.

On the other hand, according to a fourth invention of the present invention, according to any one of the first to third inventions, a first method of bringing a solution containing phosphoric acid into contact with a rare earth-iron-based magnet powder in a pulverization vessel or a stirring vessel. Step 2, a second step of heat-treating the contact-treated rare earth-iron magnet powder in a non-oxidizing atmosphere at a temperature range of 100 to 300 ° C., the heat-treated rare earth-iron magnet powder again with phosphoric acid A third step of contacting the solution containing the mixture in a stirring vessel, and a fourth step of sequentially heating the contact-treated rare earth-iron-based magnet powder in a non-oxidizing atmosphere at a temperature range of 80 to 200 ° C. Thus, a method for producing a rare earth-iron-based magnet powder, characterized in that a film with a reduced amount of Fe present in a metallic state is formed on the surface of the rare earth-iron-based magnet powder, is provided.
According to a fifth aspect of the present invention, in the fourth aspect, the solution containing phosphoric acid contains one or more alcohols selected from ethanol or 2-propanol (IPA) as the organic solvent. A method for producing a rare earth-iron-nitrogen based magnet powder for a bonded magnet is provided.

The rare earth-iron-based magnet powder for bonded magnets of the present invention is a rare earth element-iron-based magnet powder having a film containing Fe, P, O, RE (RE is a rare earth element) having a film thickness of 100 nm or less. The amount of Fe present in the state is reduced to 2.0% or less when calculated based on the area of the spectrum profile obtained after measuring the Fe2p _3/2 spectrum on the surface of the magnet powder with an X-ray photoelectron spectrometer. Therefore, the moldability of the composition for bonded magnets is excellent, and the mechanical strength of the obtained molded product can be improved.
Therefore, since the rare earth element-iron-based magnet powder of the present invention is extremely useful in a wide range of fields such as general home appliances, communication / acoustic equipment, medical equipment, general industrial equipment, etc., its industrial value is very high. high.

It is a chart when the Fe2p _3/2 profile of the magnet powder film obtained by the surface treatment with the conventional phosphoric acid solution and the profile are separated into waveforms. It is a chart when the profile of the magnet powder obtained by repeatedly performing the surface treatment with the phosphoric acid solution with respect to the magnet powder surface-treated with the phosphoric acid solution according to the present invention and the profile are separated into waveforms.

  Hereinafter, the rare earth-iron-based magnet powder for bonded magnet of the present invention and the production method thereof will be described. The rare earth-iron-based magnet powder for bonded magnets of the present invention may hereinafter be referred to as surface-coated magnet powder.

1. Surface-coated magnet powder In the surface-coated magnet powder of the present invention, a film having a thickness of 100 nm or less made of Fe, P, O, RE (RE is a rare earth element) is formed on the surface of a magnet powder made of an iron-based magnet alloy containing a rare earth element. When the amount of Fe present in a metallic state in the coating is calculated based on the area of the spectrum profile obtained after measuring the Fe2p _3/2 spectrum on the magnet powder surface with an X-ray photoelectron spectrometer 2.0% or less.

The type of the magnetic powder to be coated on the surface is not particularly limited as long as it is a powder of an iron-based magnet alloy containing a rare earth element. For example, various magnetic powders such as NdFeB, Sm ₂ (Co, Fe, Cu, M) ₁₇ and SmFeN can be used.
Examples of rare earth elements include Sm, Nd, Pr, Y, La, Ce, and Gd, and these can be used alone or as a mixture. Among these, those containing 5 to 40 atomic% of Sm or Nd and 50 to 90 atomic% of Fe are particularly preferable. The SmFeN alloy powder production method includes a casting method and a reduction diffusion method. In the present invention, the reduction diffusion method is particularly suitable.
The iron-based magnet powder containing a rare earth element may be mixed with various magnet powders such as ferrite and alnico, which are raw materials for bonded magnets and compacted magnets.

  In the present invention, a magnet powder made of an iron-based magnet alloy containing a rare earth element is brought into contact with a treatment liquid containing phosphoric acid, and then heated and dried at a specific temperature, and the contact treatment with the phosphoric acid and the heating and drying treatment are repeated. As a result, a film having a specific thickness including Fe, P, O, and RE (RE is a rare earth element) is formed on the surface. The thickness of this film is an average of 100 nm or less, and when it exceeds 100 nm, the magnetic properties deteriorate. If the average thickness is less than 1 nm, the moldability is not improved so much, and therefore it is preferably 10 to 90 nm. The film thickness of the inorganic-organic composite coating can be confirmed from an electron micrograph of a cross section of the iron-based magnet powder containing a rare earth element that has been coated.

In the present invention, the amount of Fe present in a metallic state in the coating is measured and evaluated by an X-ray photoelectron spectrometer (XPS) as follows.
First, the Fe2p _3/2 spectrum is measured with a monochrome X-ray source (AlKα ray). Next, by using the analysis software (spectrum processing) built in XPS for the spectrum profile obtained in the range of binding energy of 705 eV to 720 eV, a profile baseline is set based on the Shirley method, and the waveform of iron Fe in the metallic state The waveform is divided into three waveforms: P1, a waveform P2 in the form of iron Fe oxide, and a waveform P3 in another oxide form of iron Fe. Then, the area of each waveform of P1, P2, and P3 is calculated, and the waveform area of the waveform P1 of the iron Fe in the metallic state with respect to the sum of these three waveform areas is obtained as a percentage.

In the case of a magnet powder obtained by a conventional surface treatment method using a phosphoric acid solution, a chart as shown in FIG. 1 was obtained when the coating was subjected to waveform separation of the Fe2p _3/2 profile using an X-ray photoelectron spectrometer. So far, it has been clearly shown that a magnet powder obtained by a surface treatment method using a phosphoric acid solution is formed with a coating composed of at least two kinds of forms of iron Fe in a metallic state and a form containing an oxide of iron Fe. It has become. In FIG. 1, the waveform of iron Fe in the metal state is P1, and the waveforms of oxide forms of iron Fe are P2 and P3. There are iron oxides such as FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , and FeOOH in the form of iron-Fe oxide, and some of them are considered to be complex oxides with rare earth elements, carbon, and hydrogen. It is done.

Thereafter, the respective waveform areas of P1, P2, and P3 were calculated, and when the waveform area of the waveform P1 of the iron Fe in the metallic state with respect to the sum of these three waveform areas was obtained, the area percentage exceeded 3%.
As a result of further investigation, when using a magnetic powder in which the percentage of the waveform P1 of the iron Fe in the metal state exceeds 2.0%, the torque when kneading with the binder resin is high, and the fluidity Q value of the resulting composition Is known to decrease. Further, the mechanical strength of the bonded magnet obtained by molding the composition is lowered.

On the other hand, when the surface treatment with a phosphoric acid solution is further performed on the powder according to the present invention, the obtained magnet powder is obtained by separating the coating from the Fe2p _3/2 profile with an X-ray photoelectron spectrometer. A chart as shown in FIG. 2 was obtained. It can be seen that the iron Fe in the metal state cannot be visually observed, and is composed of only the waveform P2 of the iron Fe oxide form and the waveform P3 of the iron Fe oxide form different from P2. The reason for the disappearance of the metallic iron Fe waveform has not yet been completely clarified, but it is presumed that the iron iron in the metallic state has changed to an oxide of iron Fe by repeating the phosphoric acid treatment. Thereafter, the respective waveform areas of P1, P2, and P3 are calculated in the same manner, and the waveform area of the iron Fe (P1) in the metallic state with respect to the total of these three waveform areas is obtained, the area percentage is 0.1%. Met.
As a result of further investigation, when a magnetic powder having a corrugated area ratio of metallic iron Fe (P1) of 2.0% or less is used, the torque when kneading with the binder resin is lowered, and the fluidity of the resulting composition It has been found that the Q value increases and the mechanical strength of the bonded magnet obtained by molding the composition increases.

  The rare earth-iron-based magnet powder for bonded magnets preferably has a P content of 0.1% by weight or more in the case of NdFeB, and the P content in the case of SmFeN is 0.5%. A weight percent or more is preferred. Further, in both NdFeB magnets and SmFeN magnets, the C content is preferably 0.1% by weight or less, and the H content is preferably 0.1% by weight or less.

2. Method for producing surface-coated magnet powder The iron-based magnet powder containing a rare earth element of the present invention is subjected to a contact treatment in a first step of bringing a solution containing phosphoric acid into contact with a rare earth-iron-based magnet powder in a pulverization vessel or a stirring vessel. A second step of heat-treating the rare earth-iron-based magnet powder in a non-oxidizing atmosphere at a temperature range of 100 to 300 ° C., the heat-treated rare earth-iron-based magnet powder again with a solution containing phosphoric acid and a stirring vessel A rare earth-iron by sequentially performing a third process in which the contact is performed, and a fourth process in which the contact-treated rare earth-iron-based magnet powder is heat-treated in a non-oxidizing atmosphere in a temperature range of 80 to 200 ° C. A film having a reduced amount of Fe present in a metallic state is formed on the surface of the system magnet powder.

(First step)
The first step is a step of bringing a solution containing phosphoric acid into contact with a rare earth-iron-based magnet powder in a pulverization vessel or a stirring vessel.
Examples of the solution containing phosphoric acid used in the present invention include orthophosphoric acid that reacts with a metal compound to form a metal phosphate, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, linear polyphosphoric acid, cyclic metaphosphoric acid. Phosphoric acid is mentioned. Ammonium phosphate, ammonium magnesium phosphate, and the like can also be used. Among phosphoric acids, orthophosphoric acid exhibits a preferable performance because it is easy to react with the above metal compound and to form a protective film on the surface of the magnet powder containing rare earth metal as a component. . These compounds may be used alone or in combination of a plurality of types, and are usually mixed with an organic solvent, a chelating agent, a neutralizing agent and the like to form a treating agent.
The organic solvent is not particularly limited, and alcohols such as isopropyl alcohol, ethanol and methanol, lower hydrocarbons such as pentane and hexane, aromatics such as benzene, toluene and xylene, ketones, and mixtures thereof are used. However, ethanol and isopropyl alcohol are particularly preferable from the viewpoint of safety.

Phosphoric acid is added in an optimum amount according to the particle size, surface area, etc. of the magnet powder. Usually at 0.1 to 2 mol / kg as _H 3 PO ₄ with respect to the magnet powder (powder weight per), preferably 0.15~1.5mol / kg, more preferably 0.2~0.4mol / Kg. If the amount of phosphoric acid added is less than 0.1 mol / kg, the surface of the magnet powder will not be sufficiently coated, so that the salt water resistance will not be improved. descend. When it exceeds 2 mol / kg, the reaction with the magnet powder occurs vigorously and the magnet powder is dissolved. The concentration of phosphoric acid is not particularly limited, and phosphoric anhydride, 50-99% phosphoric acid aqueous solution, or the like is used.

Thereafter, if the magnet powder is NdFeB-based or Sm ₂ (Co, Fe, Cu, M) _17- based, it is stirred in a treatment liquid containing phosphoric acid. In the case of SmFeN, it is preferable to stir while pulverizing.
The stirring time and pulverization time vary depending on the size of the apparatus, the particle size of the magnetic powder to be treated and the amount of treatment, and cannot be defined unconditionally, but are preferably 0.1 to 3 hours in a treatment solvent having a predetermined phosphoric acid concentration. Is 0.1 to 2 hours. If the time is less than 0.1 hour, a phosphate film having a sufficient thickness is not formed on the surface of the magnet powder, and if it exceeds 3 hours, the magnet powder tends to aggregate, which is not preferable. In the method of the present invention, by adding an appropriate amount of phosphoric acid at the time of pulverization of the magnet alloy powder, a coating film is formed on the surface of the magnet powder by a mechanochemical action, so that the drying time can be shortened.

(Second step)
The second step is a step of subsequently heat-treating the rare earth-iron-based magnet powder in an inert gas or in a vacuum at a temperature range of 100 to 300 ° C.
Here, the magnet powder obtained in the first step is obtained as an alloy powder cake in a slurry containing a large amount of treatment liquid. The liquid content of the slurry is preferably 5 to 30% by weight, and more preferably the slurry is treated and adjusted in the solid-liquid separator so as to be 10 to 30% by weight. For the heat treatment, a mixer type dryer, a processed product stationary type box type dryer, or the like can be used. A mixer type dryer is preferred.

The heat treatment atmosphere may be a non-oxidizing atmosphere, and when an inert gas is used, a nitrogen atmosphere or an argon atmosphere can be used. Moreover, although it depends on the apparatus to be used, it is preferable that the pressure at the start of temperature rise is 70 kPa to 100 kPa in absolute pressure, and the pressure after evaporation of dehydrated ethanol and the pressure in the drying operation are 5 kPa or less in absolute pressure.
The heat treatment temperature is set to a temperature range of 100 to 300 ° C. When the heat treatment temperature is less than 100 ° C. or exceeds 300 ° C., metallic iron remains on the surface treatment film, and the formability of the bonded magnet composition and the mechanical strength of the molded product are not improved. In particular, when the temperature is less than 100 ° C., the denseness of the surface-treated film is insufficient, and the amount of carbon and hydrogen contained in the magnet powder is large, so that the coercive force is lowered.
The heat treatment time varies depending on the size of the apparatus, the particle size of the magnetic powder to be treated, the amount of treatment, and the like, and cannot be defined generally, but it is desirable that the heat treatment time be as short as possible. For example, when processing 50 kg of magnetic powder with a 100 liter stirring type dryer, the time is within 3 hours, particularly within 2 hours. The longer the heat treatment time, the lower the magnetic properties. However, if it is shorter than 10 minutes, a stable phosphate coating may not be formed.

(Third process)
The third step is a step of bringing the rare earth-iron-based magnet powder obtained in the second step into contact with a solution containing phosphoric acid again in a stirring vessel.
The rare earth-iron-based magnet powder obtained in the second step is pulverized in the treatment liquid to which phosphoric acid has been added, and a phosphate film is formed on the surface. Since the fine powder is aggregated with each other by magnetic force or the like, the fluidity is poor. For this reason, it is treated again with an organic solvent to which phosphoric acid is added, and a coating treatment is performed on the contact surface of the magnet powder.

The kind of phosphoric acid is not particularly limited as in the first step, and commercially available phosphoric acid can be used. The amount of phosphoric acid added is generally unrelated because it is related to the particle size, surface area, and the like of the magnet powder after pulverization, but is usually 0.03 to 1 mol / kg, more preferably 0 to the magnet powder. 0.05 to 0.5 mol / kg is preferable. If it is less than 0.03 mol / kg, the surface treatment of the magnet powder is not sufficiently performed, so that the fluidity of the compound is not improved. However, if it exceeds 1 mol / kg, the magnetic properties of the bonded magnet may deteriorate.
The treatment time is 1 to 60 minutes, preferably 5 to 30 minutes in an organic solvent having a predetermined phosphoric acid concentration. If it is less than 1 minute, the surface of the magnet powder is not uniformly coated with a phosphate coating having a sufficient thickness, and if it exceeds 60 minutes, the fluidity is not greatly improved.

(Fourth process)
The fourth step is a step of heat-treating the rare earth-iron-based magnet powder obtained in the third step in a temperature range of 80 to 200 ° C. in an inert gas or vacuum.
Here, the heat treatment conditions such as the heating atmosphere are the same as those in the second step except for the treatment temperature. The treatment temperature may be higher or lower than the temperature in the second step as long as it is in the temperature range of 80 to 200 ° C. When the treatment temperature is less than 80 ° C. or exceeds 200 ° C., metallic iron remains on the surface treatment film, and the formability of the bonded magnet composition and the mechanical strength of the molded product are not improved. In particular, when the temperature is less than 80 ° C., the denseness of the surface-treated film is insufficient, and the amount of carbon and hydrogen contained in the magnet powder is large, so that the coercive force is lowered.
As described above, in the present invention, the magnet powder is brought into contact with the treatment liquid containing phosphoric acid, and then a heat drying treatment is performed at a specific temperature to form a film, and the contact treatment with the phosphoric acid and the heat drying treatment are repeated. As a result, the amount of Fe in the metal state is reduced.

3. Bonded Magnet Resin Composition A bonded magnet composition is obtained by mixing the rare earth-iron-based magnet powder with a resin binder.

The type of the resin binder is not particularly limited, and may be various thermoplastic resins alone or a mixture, or various thermosetting resins alone or a mixture, and their physical properties and properties may be within a range where desired characteristics can be obtained. There is no particular limitation.
The thermoplastic resin is not particularly limited as long as it functions as a binder for the magnet powder, and a conventionally known one can be used. Specific examples include 6 nylon, 6-6 nylon, 11 nylon, 12 nylon, 6-12 nylon, aromatic nylon, polyamide resins such as modified nylon partially modified from these molecules, and linear polyphenylene sulfide. Resin, cross-linked polyphenylene sulfide resin, semi-cross-linked polyphenylene sulfide resin, low density polyethylene, linear low density polyethylene resin, high density polyethylene resin, ultrahigh molecular weight polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, ethylene- Ethyl acrylate copolymer resin, ionomer resin, polymethylpentene resin, polystyrene resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polyvinyl chloride resin, polyvinylidene chloride Fatty, polyvinyl acetate resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyvinyl formal resin, methacrylic resin, polyvinylidene fluoride resin, polytrifluoroethylene chloride resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, ethylene- Tetrafluoroethylene copolymer resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, polytetrafluoroethylene resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene oxide resin, polyallyl ether allyl Sulfone resin, polyethersulfone resin, polyetheretherketone resin, polyarylate resin, aromatic polyester resin, cellulose acetate resin, resin-based elastomer Mer, and the like, random copolymers of these homopolymers and other species monomer, block copolymers, graft copolymers, and end groups modified products with other substances. Particularly preferred are polyamide resins such as 6 nylon, 6-6 nylon, 11 nylon, 12 nylon, 6-12 nylon, aromatic nylon, and modified nylon obtained by partially modifying these molecules.

The compounding quantity of a thermoplastic resin is 5-50 weight part normally with respect to 100 weight part of magnet powder, Preferably it is 5-30 weight part, More preferably, it is 5-15 weight part. When the blending amount of the thermoplastic resin is less than 5 parts by weight, the kneading resistance (torque) of the composition is increased, the fluidity is lowered, and it becomes difficult to mold the magnet. The magnetic characteristics cannot be obtained. Various coupling agents, lubricants, various stabilizers, and the like can be blended in order to improve the heat fluidity and the like of the composition for bonded magnets as long as the object of the present invention is not impaired.
Various mixers, kneaders, and extruders can be used to mix and knead the magnet alloy powder and the resin binder.

  The composition for bonded magnets is excellent in fluidity measured based on the melt index MI method test method. The fluidity is specifically determined by using a melt indexer manufactured by Toyo Seiki Co., Ltd., and when the resin binder is polyamide, the heating temperature is 250 ° C., the load is 21.6 kg, and the die is 2.1 mm in diameter × The fluidity (cc / sec) is evaluated from the time required for a compound having a predetermined weight to pass through a thickness of 8 mm. It can be said that the obtained composition for bonded magnets having a fluidity value of 0.1 cc / sec or more is practically preferable.

4). Bond magnet The bonded magnet resin composition can be manufactured by molding by a molding method such as an injection molding method, a compression molding method, an extrusion molding method, or an injection press molding method.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited at all by these Examples.

(1) Component magnet powder:
SmFeN alloy powder (coarse powder) [Sumitomo Metal Mining Co., Ltd. average particle size: 30 μm]
NdFeB alloy powder [Magnequen International, MQP-B, average particle diameter: 47 μm]
Treatment liquid:
・ 85% orthophosphoric acid aqueous solution [manufactured by Kanto Chemical Co., Inc.]
Binder resin:
・ Polyamide (PA12, manufactured by Ube Industries)

(2) Evaluation method (2-1) Amount of metallic Fe on the surface of the magnet powder The surface-treated magnet powder was fixed tightly on a conductive tape, and then an X-ray photoelectron spectrometer (XPS, ESCALAB220i-XL manufactured by VG Scientific). The state was analyzed. Focusing on the Fe2p _3/2 spectrum as an analysis of the state of iron, the analysis area was set to φ0.6 mm so that average information on the sample surface could be obtained. The Fe2p _3/2 spectrum profile obtained in the range of binding energies of 705 eV to 720 eV is set based on the Shirley method by spectrum processing, which is analysis software built in the XPS, and a metallic state iron is set. The waveform is divided into three waveforms: a waveform P1 of Fe, a waveform P2 of an oxide form of iron Fe, and a waveform P3 of another oxide form of iron Fe. Thereafter, the respective waveform areas of P1, P2, and P3 are calculated. The percentage of the corrugated area of the corrugated P1 of iron Fe in the metallic state relative to the sum of these three corrugated areas was determined.
As for the waveform separation, as an initial value for the spectrum processing, a center value 707.4 eV and a half-value width 1.06 eV for P1, a center value 711.2 eV and a half-value width 3.02 eV for P2, and a center value 713 for P3. 0.0 eV and a half width of 5.3 eV are input, and thereafter, the following processing is executed in the software. That is, the difference in intensity at the binding energy is calculated for the combined waveform of the separated waveforms and the actually measured waveform, and the center value and the half width are obtained so that this difference is minimized. The spectrum processing calculates a percentage of the area of the waveform P1 of Fe in the metallic state with respect to the sum of the waveform areas of P1, P2, and P3 corresponding to the value width.

(2-2) Fluidity (Melt Index MI Method)
Using a Toyo Seiki Co., Ltd. melt indexer, a heating temperature of 250 ° C, a load: 21.6 kg, a die: 2.1 mm in diameter x 8 mm in thickness From the time required for a compound to pass through a predetermined weight, The fluidity (cc / sec) was evaluated.

[Examples 1-5, Comparative Examples 1-6]
As a first step, 3 kg of SmFeN alloy powder was pulverized to a mean particle size of 2.0 μm using a medium stirring mill in a mixed solution of 4 kg of dehydrated ethanol and a treatment liquid having an amount shown in Table 1. Here, the average particle diameter is calculated on a volume basis by measuring the particle size distribution with a laser diffraction particle size distribution analyzer HELOS & RODOS manufactured by Sympatec. Note that the amount of the treatment liquid corresponds to 0.3 mol / kg with respect to the magnet powder.
Next, as a second step, the pulverized slurry is put into a mixer, a nitrogen atmosphere is maintained as a non-oxidizing atmosphere, and the temperature is increased at an absolute pressure of 70 kPa, and the temperature shown in Table 1 is reached in 2 hours. And was held for 2 hours for further drying. Since dehydrated ethanol evaporates during the temperature rise, when the evaporation was completed, the pressure became 5 kPa, and the drying operation was performed while maintaining this pressure.
As a third step, the amount of treatment liquid shown in Table 1 was dispersed in 3 kg of dehydrated ethanol, added to the cooled magnet powder, and stirred for 30 minutes. Note that the amount of the treatment liquid corresponds to 0.1 mol / kg with respect to the magnet powder.
Subsequently, as the fourth step, a nitrogen atmosphere is maintained as a non-oxidizing atmosphere, temperature increase is started at a pressure of 70 kPa, the temperature shown in Table 1 is reached in 2 hours, and the temperature is further maintained for 2 hours for drying. did. Since dehydrated ethanol evaporates during the temperature rise, when the evaporation was completed, the pressure became 5 kPa, and the drying operation was performed while maintaining this pressure.
The magnet powder collected after cooling was subjected to elemental analysis by qualitative analysis of the surface film with an X-ray photoelectron spectrometer for the film component, and the amount of metallic Fe on the surface of the magnet powder was determined.
The results are shown in Table 1. As for Comparative Example 1, an example of waveform separation is shown in FIG. 1, and Example 1 is shown in the figure. About these magnet powders, when the thickness of the surface film was confirmed with the transmission electron microscope, the film thickness was 10-50 nm about all the samples containing a comparative example.
Next, the obtained magnet powder was mixed with a binder resin and kneaded for 30 minutes with a lab plast mill to obtain a bonded magnet composition. Next, this composition was injection molded to obtain a 40 × 8 × 2 mm molded product, and the bending strength by three-point bending was evaluated. Table 1 shows the magnetic powder ratio, the binder resin, and the kneading temperature, which are the weight ratio of the magnet powder in the kneaded product. Table 1 also shows the kneading torque after 30 minutes of kneading, the fluidity Q value of the obtained composition, the temperature of injection molding, and the bending strength of the obtained molded body.

[Examples 6 to 8, Comparative Examples 7 to 11]
As a first step, 3 kg of NdFeB alloy powder was stirred for 30 minutes using a mixer in a mixed solution of 4 kg of dehydrated ethanol and the treatment liquid shown in Table 2. Note that the amount of the treatment liquid corresponds to 0.3 mol / kg with respect to the magnet powder. Next, as the second step, operations other than the temperatures described in Table 2 were performed in the same manner as the second step described in [Examples 1 to 5, Comparative Examples 1 to 6].
As a third step, the treatment liquid shown in Table 1 was dispersed in 3 kg of dehydrated ethanol, added to the cooled magnet powder, and stirred for 30 minutes. Note that the amount of the treatment liquid corresponds to 0.1 mol / kg with respect to the magnet powder. Subsequently, as the fourth step, operations other than the temperatures described in Table 2 were performed in the same manner as the fourth step described in [Examples 1 to 5, Comparative Examples 1 to 6]. In addition, about the comparative example 11, the process of a 1st process to a 4th process is not performed.
A qualitative analysis of the surface coating and the amount of metallic Fe were determined with an X-ray photoelectron spectrometer for the magnet powder collected after cooling. The results are shown in Table 2. Moreover, about these magnet powders, when the thickness of the surface film was confirmed with the transmission electron microscope, about samples other than the comparative example 11, the film thickness was 10-90 nm.
Next, the obtained magnet powder was mixed with a binder resin and kneaded with a lab plast mill for 30 minutes to obtain a bonded magnet composition. Next, this composition was injection molded to obtain a 40 × 8 × 2 mm molded product, and the bending strength by three-point bending was evaluated. Table 2 shows the magnetic powder ratio, binder resin, and kneading temperature of the kneaded product. Table 2 also shows the kneading torque after 30 minutes of kneading, the fluidity Q value of the obtained composition, the temperature of injection molding, and the bending strength of the obtained molded body.

"Evaluation"
In the case of SmFeN magnet powder, the example in which the Fe amount in the metal state is 2.0% or less is smaller in the kneading torque than the comparative example in which the Fe amount in the metal state exceeds 2.0%. Since the Q value indicating the property is increased, the moldability is improved, the bending strength of the molded body is increased, and the mechanical strength is also increased.
In the case of NdFeB magnet powder, the relationship between the example in which the Fe amount in the metal state is 2.0% or less and the comparative example in which the Fe amount in the metal state exceeds 2.0% is the same as that of the above-described SmFeN magnet powder. Same as the case.

Claims (5)

In a rare earth element-iron-based magnet powder having a film containing Fe, P, O, RE (RE is a rare earth element) with a film thickness of 100 nm or less on the surface, the amount of Fe present in a metallic state in the film is determined by the surface of the magnet powder. After measuring the Fe2p _3/2 spectrum with an X-ray photoelectron spectrometer, it is 2.0% or less when calculated based on the area of the obtained spectrum profile. Magnet powder. The amount of Fe present in a metallic state in the coating is first measured using the Fe2p _3/2 spectrum profile obtained by measuring the X-ray photoelectron spectrometer in the range of binding energy of 705 eV to 720 eV based on the Shirley method. A baseline is set and separated into three waveforms: a waveform P1 of iron Fe in a metallic state, a waveform P2 of an oxide form of iron Fe, and a waveform P3 of another oxide form of iron Fe, and then P1, P2 The bond magnet according to claim 1, wherein the area of each waveform of P3 is calculated and determined as a percentage of the waveform area of the waveform P1 of iron Fe in a metallic state with respect to the sum of these three waveform areas. Rare earth-iron-based magnet powder. Rare earth - iron magnet powder, NdFeB _{series, Sm 2 (Co, Fe,} Cu, M) 17 type, or rare earth bonded magnet according to claim 1, characterized in that the SmFeN system - iron-based magnetic powder .   A first step of bringing a solution containing phosphoric acid into contact with a rare earth-iron-based magnet powder in a pulverization vessel or a stirring vessel, the contact-treated rare earth-iron-based magnet powder at a temperature of 100 to 300 ° C. in a non-oxidizing atmosphere The second step of heat treatment in the range, the third step of bringing the heat-treated rare earth-iron-based magnet powder into contact with the solution containing phosphoric acid again in a stirring vessel, the contact-treated rare earth-iron-based magnet powder By sequentially performing a fourth step of heat treatment in a temperature range of 80 to 200 ° C. in a non-oxidizing atmosphere, a coating with a reduced amount of Fe present in a metallic state is formed on the surface of the rare earth-iron-based magnet powder. It forms, The manufacturing method of the rare earth-iron type magnet powder in any one of Claims 1-3 characterized by the above-mentioned.   The rare earth-iron-nitrogen based magnet for bonded magnets according to claim 4, wherein the solution containing phosphoric acid contains one or more alcohols selected from ethanol or 2-propanol (IPA) as the organic solvent. Powder manufacturing method.

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