JPH0464202A - Bonded magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase residual flux density by a method wherein a raw material composed of specific R-Fe-B group magnetic powder is kneaded at a temperature, where an epoxy resin is liquefied, and cured and treated, a mixture is cracked, and a curing agent in quantity required for complete curing is mixed uniformly, and pressed and cured. CONSTITUTION:An epoxy resin and a curing agent adjusted so that the degree of cure of is 20% or more, are contained at a weight ratio from 0.05% to 2.0%, the mean grain size of the remainder is 10mum or more, and mean crystal grain size in magnetic powder extends over 0.01mum to 0.5mum. A raw material consisting of the R-Fe-B group magnetic powder (R represents one kind or more of rare earth elements containing Y) is kneaded at a temperature, where the epoxy resin is liquefied, and cured and treated, a mixture is cracked and a curing agent in quantity required for complete curing is mixed uniformly. Accordingly, since the epoxy resin is liquefied, the uniform layer of the resin is formed on the surface of magnetic powder, and a complete cured film is acquired, thus preventing thermal deterioration for a prolonged term of magnetic flux.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an R-Fe-B bonded magnet (R is a rare earth element).
It is related to.

[Conventional technology]

In the bonded magnet market, ferrite-based magnetic powder has traditionally been used, but with the demand for downsizing in OA equipment and precision equipment, SmCo-based bonded magnets with high energy products have been put into practical use (Japanese Patent Publication No. 56 -31841.53-3
2330.5334640.58-36641).

R-Fe-B sintered magnets developed in recent years
46008) is widely put into practical use because of its higher residual magnetic flux density and lower price than conventional Sm--Co based sintered magnets.

However, R-Fe-B alloys do not exhibit the coercive force required for bonded magnets in a pulverized state of 1 μm or more and 1 mm or less. For this reason, an R-Fe-B optically isotropic bonded magnet with fine crystal grains of 0.5 μm or less is made using an ultra-quenching process (Japanese Patent Application Laid-Open No. 59211549.6O-207302).
It has been developed and put into practical use. In addition, R-Fe-B bonded magnets using ultra-quenching process and warm plastic working can be used as raw materials for anisotropic bonded magnets with high magnetic properties by pulverizing and mixing with resin. It has the advantage of
3-232301).

Conventionally, R-Fe-B bonded magnets are Sm-C.

It has a lower Curie point than other type bonded magnets, and can be used for applications such as automobile motors and servo motors at 150 to 180 degrees Celsius.
It has been thought that it is impossible to use it in high-temperature areas.

Therefore, the applicant invented and filed an application for R-Fe-B magnetic powder with improved heat resistance by adding elements such as Nb (
(Japanese Patent Application No. 63-250452, Japanese Patent Application No. 1-3039). Magnetic powder made from this alloy system can reduce the irreversible demagnetization rate to about 3% at 200°C, and is promising as a raw material for heat-resistant bonded magnets.

[Problem that the invention seeks to solve]

The present inventors fabricated a bonded magnet from the magnetic powder using liquid epoxy and powder epoxy, and the long-term thermal deterioration of magnetic flux (1
70'c x 1000 hours).

When using liquid epoxy (Japanese Patent Application Laid-Open No. 6O-20730
2) High residual magnetic flux density can be obtained due to the elimination of air gaps. However, it became clear that long-term thermal deterioration was significant. Due to the viscosity of epoxy, it is difficult to uniformly supply magnetic powder to the mold; hardening progresses over time, making it impossible to store large quantities of raw material powder; molded bodies are easily chipped and difficult to handle; There was a drawback that dimensional accuracy deteriorated due to expansion.

When powdered epoxy is used, storage stability and handling are good, but since the epoxy is solid when pressed, it is not possible to eliminate voids. For this reason, the residual magnetic flux density is low, oxygen and moisture easily enter, causing large long-term thermal deterioration, and moisture resistance.
It also had the disadvantage of poor corrosion resistance.

The heat-degraded bonded magnet has turned blackish,
It is thought that it underwent high-temperature oxidation. Coupling treatment is known as a method for improving the corrosion resistance of magnetic powder. JP-A-62-230008 discloses that the oxidation resistance of magnetic powder and the wettability of magnetic powder and resin can be improved by using a silane coupling agent. However, this improvement in oxidation resistance in @Ming is a general theory, and a specific method for improving oxidation resistance at high temperatures is not disclosed. Furthermore, this method has the disadvantage of poor powder feeding performance and poor dimensional accuracy. In JP-A-63-152111 and JP-A-64-41201, a coupling agent is also used to improve corrosion resistance, but there is no mention of high temperature oxidation.

Therefore, it is an object of the present invention to provide a bonded magnet raw material that has low long-term thermal deterioration of magnetic flux, high residual magnetic flux density, excellent moisture resistance, oil resistance, uniform powder feeding, long-term storage stability, and dimensional accuracy. .

[Means for solving problems]

The present inventor achieved the above object by uniformly and thinly coating the entire surface of the magnetic powder with a liquid epoxy resin having a high degree of curing. By using an epoxy resin with a high degree of hardening, we succeeded in obtaining a bonded magnet with little adhesion between magnetic particles. A completely cured film was obtained and the long-term thermal deterioration of magnetic flux was significantly improved.

Specifically, the following technical means were used to achieve the above objective.

That is, the weight ratio of the epoxy resin and the curing agent adjusted so that the degree of curing is 20% or more is 0.05% or more.2. 0
% or less, and the remainder is R-Fe-B magnetic powder (R is one or more types including Y The above purpose is achieved by kneading the raw materials (rare earth elements) at a temperature where the epoxy resin becomes liquid, curing the mixture, crushing the mixture, and uniformly mixing the amount of curing agent required for complete curing. Achieved. By making the epoxy resin into a liquid state, a uniform resin layer is formed on the surface of the magnetic powder, which is convenient for achieving the object of the present invention. If it becomes a gel rather than a liquid, it becomes difficult to uniformly coat the magnetic particles.

It is desirable to have a modified layer treated with a coupling agent at the interface between the R-Fe-B magnetic powder and the epoxy resin used in the method.

Furthermore, in order to improve the strength of the magnet and to improve its water resistance and oil resistance, it is desirable to impregnate it with a resin, a low melting point metal, or water glass after pressing and curing. Furthermore, mixing microcapsules containing powdered epoxy resin or liquid epoxy resin in an amount of 3 wt % or less based on the total amount of magnetic particles before pressing has a similar effect.

Further, the present invention provides a compression-molded bond magnet raw material made of R-Fe-B magnetic powder (R is one or more rare earth elements including Y) and an epoxy resin, in which the average particle size of the R-Fe-B magnetic powder is 10 ILm. or more, and the average crystal grain size in the magnetic powder is 0.
．． 0.01 μm or more and 0.5 μm or less, the amount of epoxy resin is 0.05% or more and 2.0% or less by weight, and the epoxy resin has a hardening degree of 20% or more and covers substantially the entire surface of the magnetic powder. To provide magnetic powder for a real magnet, which is characterized by: It is desirable to have a modified layer treated with a coupling agent at the interface between the R-Fe-B magnetic powder and the epoxy resin.

The present invention also provides a compression-molded bonded magnet raw material made of R-Fe-B magnetic powder (R is one or more rare earth elements including Y) and an epoxy resin, in which the average particle size of the R-Fe-B magnetic powder is 10 μm. The average crystal grain size within the magnetic powder is 0.
0.01 μm or more and 0.5 μm or less, the amount of epoxy resin is 0.05% or more and 2.0% or less by weight, and the epoxy resin has a hardening degree of 20% or more and covers substantially the entire surface of the magnetic powder. To provide a bonded magnet characterized by:

It is desirable that the magnet has a modified layer treated with a coupling agent at the interface between the R-Fe-B thread magnetic powder and the epoxy resin. In addition, the coupling agent may be γ-aminopropyl trimethoxysilane, N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane, β-
One type or a mixture of two or more types selected from (3,4-epoxycyclohexyl)-dityltrimethoxysilane, γ-glycidoxypropyl trimethoxysilane, and γ-N-phenylaminopropyl trimethoxysilane. Yes, the amount added to the magnetic powder is 0.05% or more by weight1. More preferably, it is 0% or less. If the amount added to the magnetic powder is less than 0.05% or 5% by weight, the coupling effect will be small because it will be difficult to uniformly supply the magnetic powder to the surface of the magnetic powder. Moreover, if the amount added exceeds 1.0%, the adhesive strength with the epoxy resin will decrease, which is undesirable because the tensile strength of the product will decrease. Especially 0.2% or more.
When it is less than 4%, the strength of the magnet increases.

Furthermore, the present invention provides a bonded magnet impregnated with a resin, a low melting point metal, or water glass after pressing and curing in order to improve the strength of the magnet, water resistance, and oil resistance. 3. Similar objects The present invention provides a bonded magnet in which magnetic particles coated with epoxy resin are bonded to each other with 3 wt % or less of epoxy resin added to the total amount of magnetic particles before pressing.

The above R-Fe-B magnetic powder, RvFewCox13yM
z (R is one or more rare earth elements including Y, M is Ga,
Zn, Si, Al, Nb, Ta, W, Ti, Zr, Hf
, one or more of the elements consisting of Mo, P, C, Cu, and Ni and unavoidable impurities), and 10≦v≦1
6, W=lQQ-qx-y-z, O≦x≦30.4≦y
It is desirable that ≦11.0 x Z≦3.

Further, it is preferable that the epoxy resin is one type or a mixture of two or more types selected from bisphenol A type epoxy, nophorac type epoxy, polyfunctional epoxy, and glycidyl type epoxy.

Further, it is preferable that the curing agent added at the time of crosstalk is mainly diaminodiphenylmethane or 4.4'' diaminodiphenyl sulfone.

In addition, aluminum stearate, zinc stearate, calcium stearate, as lubricants in the epoxy resin,
Contains one or a mixture of two or more selected from molten wax, silicone surfactant, and alcohol lubricant, and has a blending ratio of 1 wt% or more with respect to the epoxy resin.1
It is desirable that it be 0 wt% or less. If it is less than 1 wt%, the lubrication effect is insufficient and mutual adhesion of magnetic particles occurs. 10w
If it exceeds t%, a strong film of residual lubricant will be formed on the surface of the magnetic powder, which will reduce the wettability of the magnetic powder with the epoxy resin, resulting in a decrease in the strength of the bonded magnet, which is undesirable.

Further, the curing agent for complete curing is a powder of one type or a mixture of two or more types selected from an imidazole type curing agent, an amine type curing agent, or a trifluoroboric acid compound.

Further, according to the present invention, an anisotropic bonded magnet with a good degree of orientation can be obtained.

In the present invention, the R-Fe-B magnetic powder has R2 as the main phase.
It means magnetic powder having Fe14B or R2(Fe, Co)14B. By rapidly cooling molten metal using a molten metal quenching method such as the single roll method, twin roll method, or ultrasonic gas atomization method, it is possible to create alloy powder that is in an amorphous state or has fine crystals. .

The reason for determining the desirable composition range in the present invention is as follows. When the amount of R (one type or combination of two or more types of rare earth elements including Y) is less than 10 at%, sufficient coercive force cannot be obtained because rare earth-rich components are not present at grain boundaries. When R exceeds 16 at%, the amount of the main phase decreases, and coarse crystal grains exceeding 0.5 μm are likely to occur, resulting in a decrease in residual magnetic flux density. Therefore, it was set as 10≦R≦16. In particular, when 10≦R≦13, it is possible to simultaneously achieve high residual magnetic flux density and coercive force, which is desirable.

When the amount of B is 4 at% or less, Nd, which is the main phase of the water-based magnet,
The 2Fe14B phase is not completely formed, and both the residual magnetic flux density and coercive force are low. Furthermore, when the amount of B exceeds 11 at %, the residual magnetic flux density decreases due to the appearance of phases that are unfavorable in terms of magnetic properties.

Therefore, the amount of B was set to 4≦y≦11. A particularly preferred range for energy product and coercive force is 5≦y≦7.

Although the Curie point improves by adding CO, the anisotropy constant of the main phase decreases, making it impossible to obtain a high coercive force. Therefore, the amount of CO was set to 30 at% or less.

Additional elements include Ga, Zn, Si, Al, Nb, Ta
, W, Ti, Zr, Hf, Mo, P, C1Cu, and Ni are selected for the following reasons.
, Zn, Si, Al, Nb, Ta, W, Ti, Zr, H
f, %o, and P are effective in improving coercive force. Addition of more than 3 at% significantly reduces coercive force. C mixed into the raw material during the reduction process of rare earth elements and boron does not reduce the coercive force as long as it is 3 at% or less. Cu and Ni improve corrosion resistance without significantly changing magnetic properties. Ga also has the effect of improving corrosion resistance.

By heat-treating this alloy powder in the range of 550'C to 750'C in an inert gas or vacuum, the average crystal grain size is 0.01 μm or more. Magnetically isotropic magnetic powder of 5 μm or less can be obtained. However, if the rapid cooling rate can be appropriately controlled, this heat treatment step can be omitted. Here, magnetic isotropy refers to a phenomenon in which the residual magnetic flux density does not change depending on the measurement direction, and corresponds to the random distribution of easy magnetization directions. The anisotropic bonded magnetic powder is obtained by subjecting the isotropic magnetic powder to plastic deformation of 50% or more at a temperature of 600°C or more and less than 900°C. As the method of plastic deformation, known hot working methods such as upsetting, rolling, and extrusion can be used. Since the easy magnetization directions of anisotropic bonded magnets are aligned, it is possible to realize a higher residual magnetic flux density than that of isotropic bonded magnets.

The average grain size varies greatly depending on the composition (particularly the amount of rare earth) and plastic working conditions (heating rate, working temperature, working time, etc.). In the present invention, the average crystal grain size was determined from the number of crystal grains crossing a straight line drawn on a photograph of a fracture surface. The reason for specifying the average crystal grain size is as follows. If the average crystal grain size is less than 0.01 μm, the coercive force required for a heat-resistant bonded magnet cannot be obtained. When the average crystal grain size exceeds 0.5 μm, the coercive force decreases and the absolute value of the temperature coefficient of the coercive force increases, resulting in large thermal demagnetization at high temperatures. In order to reduce thermal demagnetization at high temperatures in isotropic bonded magnets, the average crystal grain size should be set to 0.03 μm or more and 0.2 μm.
It is even more desirable to do the following:

The magnetic powder after heat treatment is an aggregate of the above-mentioned microcrystals, several mm in size.
It has a size of These are usually ground to 10 μm or more and 1 mm or less in order to facilitate powder feeding. The reason for specifying the average particle size is as follows. When the average particle size is less than 10 μm, the residual magnetic flux density decreases because the density decreases. In addition, the magnetic powder is oxidized by pulverization, the coercive force of the bonded magnet and the squareness of the demagnetization curve deteriorate, and thermal demagnetization at high temperatures increases. When the average particle size exceeds 1 mm, it is difficult to feed powder into a narrow cavity, but it can be used depending on the application.

The magnetic powder is cross-wired and hardened together with an epoxy resin, a hardening agent, and a lubricant, and then crushed. With this operation,
The epoxy resin covers substantially the entire surface of the magnetic powder. If the amount of epoxy resin is less than 0.05%, it cannot be used as a bonded magnet because it has no effect of adhering magnetic particles. In addition, when the amount of epoxy resin exceeds 2.0%, agglomeration of magnetic particles occurs after crosstalk, the magnetic particles are destroyed during crushing, and a new surface appears, and the epoxy resin on the surface of the magnetic particles peels off, resulting in oxidation of the magnetic particles. occurs, resulting in significant long-term thermal deterioration of magnetic flux. In the case of anisotropic bonded magnetic powder, the magnetic particles are not sufficiently oriented even when a magnetic field is applied due to agglomeration of the magnetic particles. Further, the degree of curing of the epoxy resin is defined as the value obtained by dividing the weight of the curing agent actually mixed by the weight of the curing agent necessary and sufficient to completely cure the epoxy resin. If the degree of curing is less than 20%, a complete cured film cannot be obtained even if a curing agent is added later, and the long-term thermal deterioration of the magnetic flux is significant.

It is more desirable that the degree of curing is 30% or more.

If more curing agent is added than is necessary for complete curing, the coating remains hard and long-term thermal deterioration of the magnetic flux does not worsen.

The epoxy resin is usually one type or a mixture of two or more types selected from hisphenol A type epoxy, novolak type epoxy, polyfunctional epoxy, and glycidyl type epoxy. In particular, one type or a mixture of two or more types selected from hisphenol A type epoxy and glycidyl type epoxy give good results. The epoxy resin only needs to have enough fluidity to uniformly cover the surface of the magnetic particles at the crosstalk temperature, and does not necessarily need to be liquid at room temperature. As the curing agent, general curing agents such as amine type, imidazole, trifluoroboric acid compound, etc. can be used alone or in combination of two or more types. In particular, amine-based curing agents such as diaminodiphenylmethane and 4.4" diaminodiphenyl sulfone, which can achieve a state called B stage, are industrially desirable. The reason for this is that the change in viscosity during crosstalk is small. However, Depending on the usage conditions, acid anhydrides absorb water and become acidic, which can cause magnetic particles to rust. However, non-hopyromellitic acid shows good long-term thermal deterioration of magnetic flux. Crosstalk causes the resin to flow. It is necessary to sufficiently cover the magnetic particle surface with the temperature. Since the magnetic particle surface is uniformly coated with resin, long-term thermal deterioration of the magnetic flux is improved. To improve the chemical affinity between the resin and the magnetic particle. It is preferable to react the silane-based coupling agent with the magnetic powder or mix it with the resin in advance.As stated on page 5 of Nippon Unicar's technical data ``NUc Silicone Silane Coupling Agent'',
γ-aminopropyl trimethoxysilane, N-β-(
aminoethyl)-γ-aminopropyl trimethoxysilane, β-(3,4-epoxycyclohexyl)-dityltrimethoxysilane, γ-glycidoxypropyl trimethoxysilane and γ-N-phenylaminopropyl.
Silane coupling agents with strong affinity for epoxy resins, such as trimethoxysilane, give good results.

If the amount added to the magnetic powder is less than 0.05% by weight, it is difficult to uniformly supply it to the surface of the magnetic powder, resulting in a small coupling effect. Moreover, if the amount added exceeds 1.0%, the adhesive strength with the epoxy resin will decrease, which is undesirable because the tensile strength of the product will decrease. Especially 0.2%
The strength of the magnet increases when it is less than 0.4%.

In addition, the lubricant added at the time of crosstalk to prevent adhesion between magnetic particles is one or two types selected from aluminum stearate, zinc stearate, calcium stearate, molten wax, silicone surfactant, and alcohol lubricant. It is a mixture of more than one type, and it is desirable that the blending ratio to the epoxy resin is 1 wt% or more and 10 wt% or less. Aluminum stearate, zinc stearate, and calcium stearate may cause blistering due to moisture absorption, so they are used in applications where moisture resistance is not strictly required. Examples of silicone surfactants include dimethylpolysiloxane and compounds of polyalkylene oxide and methylpolysiloxane. Alcohol-based lubricants are lubricants that have ○H groups in their side chains, and examples include 0ctad
ecil-3-(3',5'-di-tert-bu
tyl-4'-hydroxypheni 1)p
ropionate, Tetrakis [methy
lene-3-(3°, 5'-di-tert-bu
tyl-4'-hydroxyphenyl)pro
pionate] methane, etc. If the blending ratio of these lubricants to the epoxy resin is less than 1 wt%, there is no effect of suppressing adhesion between magnetic particles. Mixing ratio is 10w
If it exceeds t%, the fracture strength of the bonded magnet after complete hardening will drop significantly, requiring careful handling, which is impractical. A particularly preferable range is 2 wt% or more and 6 wt% or less.

The reaction between the resin and the curing agent by heating may be carried out simultaneously with the kneading or after the kneading, but it is necessary to allow the reaction to occur sufficiently.

The cured film thus formed prevents the resin from peeling off due to friction between magnetic particles during mechanical friction such as crushing or pressing, and reduces the generation of new surfaces due to destruction of magnetic particles. This not only improves high-temperature oxidation, but also helps suppress rust caused by moisture. The coupling treatment is preferably used to strengthen the adhesion between the magnetic powder and the cured film.

The curing agent for complete curing is a powder of one type or a mixture of two or more types selected from an imidazole type curing agent, an amine type curing agent, or a trifluoroboric acid compound,
It is desirable that the average particle size is 30 μm or less. When the average particle size exceeds 30 μm, it is difficult to mix uniformly during compounding.

By subjecting the magnetic powder to appropriate heat treatment, an isotropic bonded magnet having a coercive force at room temperature of 9 kOe or more and 15 kOe or less and an energy product after molding of 7 MGOe or more and less than 12 MGOe can be obtained.

Or the coercive force at room temperature is 10kOe or more 25ko
e or less, and the energy product after molding is 12 M G
It is possible to obtain an anisotropic bonded magnet with a diameter of Oe or more and 250 μm or less. However, anisotropic bonded magnets require compression molding in a magnetic field.

〔Example〕

Example 1 Composition formula N d 12.5 Fe bal B6.5N
A master alloy was prepared by melting raw materials weighed to b 1.5 (expressed as atomic %, the same applies hereinafter) in an Ar atmosphere using a high-frequency melting furnace. The master alloy was placed in a transparent quartz nozzle with a hole at the bottom and set on a Cu roll. After the chamber containing the roll was evacuated, Ar gas was introduced to a temperature of 760 Torr. After remelting the master alloy using high frequency, the circumferential speed was 25 m/s using an Ar pressure of 250 g/cm2.
The molten metal was spouted onto the rolls rotated by EC. The molten metal was rapidly cooled and solidified into flakes. The average thickness was 21 μm, and the coercive force was 0.4 and ○e.

The obtained flakes were held at 650° C. for 1 hour in an Ar atmosphere and then cooled in a furnace. The average crystal grain size of the obtained flakes was 0.06 μm. This flake was crushed to 250 μm or less, ○, 3 wt% of γ-glycidoxypropyl trimethoxysilane was added and mixed uniformly with a mixer, and then 9
The mixture was kept at 0° C. for 3 hours to obtain dried silane coupling-treated magnetic powder. This was supplied to a crosstalk machine maintained at 100'C. Epoxy resin (Epicoat 807 manufactured by Yuka Shell Epoxy Co., Ltd.), powder curing agent (diaminodiphenylmethane (
DDM)) and an alcohol-based lubricant (DR-28 manufactured by Adeka Argus) were mixed in a weight ratio of 100:10:3 (corresponding to a hardening degree of 33%), held at 100°C, and
After confirming that DM was dissolved in the resin, it was supplied to the mixer.

The resin ratio was varied in several steps from 0.05% to 3.0% by weight. After kneading these with Yuoo'c, they were semi-hardened at 120°C. Resin amount 2. 0%
The following mixtures hardly aggregated even when the temperature was lowered to room temperature. On the other hand, in mixtures with a resin content of 2.5% or more, agglomeration of magnetic particles was observed, and the particles were passed through a 500 μm sieve after being crushed.

6 parts by weight of 2-methyl-4-ethylimidazole fine powder was added to the crushed powder based on 100 parts by weight of the epoxy resin, and the mixture was mixed for 10 minutes in a V-type mixer to obtain a raw material for a bonded magnet.

This raw material is heated to a diameter of 12.5 mm at a pressure of 7 tons/cm2.
A bonded magnet was produced by molding to a height of 8.3 mm and curing at 170° C. for 2 hours. Table 1 shows the characteristics of the obtained bonded magnet. Energy product (BH) m
ax was tentatively measured in a magnetic field of 25 kOe. The coercive forces iHc of these magnets are all 13.3 to i4.
It was in the 0kOe range. Thermal demagnetization is performed by
After magnetization in a magnetic field of 5 and ○e, it was held at 170°C for 1000 hours, and the decrease in magnetic flux was determined by the amount of decrease in magnetic flux when the temperature was returned to room temperature.

Resin amount (wt%) 0.0 OoO O81 0, 3 0, 6 92, 50 Table 1 (BH)max Thermal demagnetization (MGOe) (%) 8, 0 7.8 7.6 7.5 7.5 6.7 5.8 5.2 4.9 7.2 18° Comparative Example Samples 2 to 8 of the present invention have a higher energy product (BH) max than Sample 9.10, and the epoxy resin Since the coating is not damaged, it has excellent long-term thermal demagnetization of magnetic flux.

Furthermore, although Comparative Example 1 had a large (BH)max, the resin layer was so thin that the adhesive force acting between the magnetic particles was weak, and the magnet collapsed during the experiment.

Example 2 A magnet raw material was produced in the same manner as Sample 5 except for the amount of curing agent used. The degree of curing of the epoxy resin was defined as the value obtained by dividing the weight of the effect agent actually mixed by the weight of the curing agent necessary and sufficient to completely cure the epoxy resin. The results are shown in Table 2. The table also shows the aggregation of magnetic particles after crosstalk.

(The following is a blank space) Table 2 Slightly Yes No No 9.8 6.8 4.7 By setting the degree of curing to 20% or more in Samples 12 to 16, a bonded magnet raw material with less adhesion between magnetic particles was realized. It is considered that sample 11 of the comparative example had large thermal demagnetization because the coating was damaged during crushing due to agglomeration of magnetic particles. Additionally, the excess curing agent found in Samples 15 and 16 has a small adverse effect on thermal demagnetization.

Example 3 A magnet was produced in the same manner as Sample 6 except that the average particle size was changed. Table 3 shows the average particle size and thermal demagnetization.

Table 3 Energy Product Bonded magnets were produced in the same manner as in Example 6 except for changing the diameter. Table 4 shows the energy product and heat resistance temperature. The heat-resistant temperature in this experiment was defined as the temperature at which 5% demagnetization occurred when the temperature was maintained for 1 hour.

Table 4 Samples other than sample 17 showed good characteristics, and it can be seen that it is sufficient to grind them to a size of μm or more.

Example 4 The heat treatment temperature of the quenched flakes was varied to increase the average crystal grain size from 0.01 μm to 0.01 μm. It can be seen that by setting the thickness to 5 μm or less, a high (BH)max and heat resistance temperature can be obtained.

Example 5 A magnet raw material was prepared in the same manner as Sample 6 except for the type and amount of the silane coupling agent used. The results are shown in Table 5. The coupling agents used in samples 32 to 35 were γ-aminopropyl trimethoxysilane and N-β, respectively.
-(aminoethyl)-γ-aminopropyl trimethoxysilane, β-(3,4-epoxycyclohexyl)-
Dityltrimethoxysilane, γ-N-phenylaminopropyl trimethoxysilane, and 36 to 39 are γ
-Glycidoxyprobyl trimethoxysilane, 40 is an example in which no coupling treatment is performed.

(Leaving space below) Table 5 Trial usage amount (BH) max Thermal demagnetization notes 7.47.1 1゜1゜7.0 6゜4゜For coupling agents of 4゜ or more, it is necessary to sacrifice a large amount of energy product. It has the effect of reducing thermal demagnetization without causing
5% or more1. It is desirable to use 0% or less.

Example 6 A bonded magnet was prepared in the same manner as Sample 7 and impregnated with various substances. The energy product did not change with impregnation.

Table 6 shows the results of thermal demagnetization.

Table 6 Test/substance name Thermal demagnetization Notes Resin 421 Epoxy resin 43, Polysiloxane 44: Polyorganosilsesquioxane 45'5n-Pb eutectic alloy 5.4 46Zn-5n co-product alloy 5.4 47" Water glass 6. 3 7.8 6.8 4.8 Mix with powdered epoxy (samples 48 to 50) and microcapsule epoxy resin (samples 51 to 53, trade name Scotch Grip 2451) and press to create bonded magnets. The results are shown in Table 7. Samples 54 and 55 are comparative examples in which magnetic powder was mixed as it was with powdered epoxy and microcapsules.

Table 7 Test: Usage amount (BH) max Material (wt%) (MGOe) 481.0 7,3 49'2.0 7.1 503.0 6.9 Thermal demagnetization Notes (%n 4.9 0. 1 5.6 Each substance except acrylic resin is desirable because it improves the strength without significantly worsening the demagnetization rate.

Example 7 When magnetic powder for bonded magnets was prepared in the same manner as Sample 14 and mixed with powdered epoxy or microcapsule epoxy, it can be seen that the demagnetization rate was greatly reduced by applying the coating treatment according to the present invention. . Further, in the present invention, by later mixing epoxy, the transverse rupture strength of the product can be improved by 3 kgf/mm, 2, which is desirable.

Trial Composition Remaining Table 8 (at%) (B) Ri■ax Demagnetization Rate Example 8 Magnets with different compositions were created. The magnetic properties are shown in Table 8. In addition, the average crystal grain size is 0゜03~0.2μ in all cases.
It was within the range of m.

(Left below) Example 9 The composition formula is Nd12. IFebalco3B6.5Mx
(M is an additive element), and a magnet was created in the same manner as Sample 7 except that the additive element was changed. The magnetic properties are shown in Table 9. In addition, the average crystal grain size is 0.02 to 0.02.
It was within the range of 1 μm.

(Margin below) Table 9 Trial 1 added element Hc Demagnetization rate notes I a n i I a r f M.

1D, 3 12.7 14.1 13, O 11,9 13,9 15,2 14,3 12,9 It can be seen that all the additives have the effect of increasing the coercive force and decreasing the demagnetization rate.

It has achieved a high Lugie product and a good demagnetization rate.

Example 10 A magnet was prepared in the same manner as Sample 7 except for the type of epoxy resin (all manufactured by Yuka Shell Epoxy Co., Ltd.) used and the amount of curing agent used. The results are shown in Table 10.

Table 10 Example 11 A magnet raw material was prepared in the same manner as Sample 51 except for the type and amount of the curing agent mixed first. Energy product and moisture resistance (
Table 11 shows the rusting after epoxy electrodeposition coating and 100 hours at 50°C and 90%RH.

Table 11 Trial Curing Agent (BH) max Moisture Resistance A particularly high energy product can be achieved by using diaminodiphenylmethane or 4.4 diaminodiphenyl sulfone as an energy curing agent of 7 MGOe or more for any resin. Methylnadic anhydride rusts in a short period of time in high temperature and humidity conditions, so it is preferable not to use it as a hardening agent in applications that require moisture resistance.

% or more and 10% or less, a bonded magnet raw material with less adhesion between magnetic particles and high strength is realized.

Example 12 A magnet raw material was produced in the same manner as Sample 8 except for the lubricant used. The results are shown in Table 12. However, the magnet strength was determined from the fracture strength when the side surface of the cylinder was compressed in parallel.

Table 12 Test lubricant Magnet strength of magnetic powder Notes Example 1
3 A magnet raw material was prepared in the same manner as Sample 6 except for the type and all of the lubricants mixed first. The results are shown in Table 13.

Table 13 Test I lubricant usage amount Moisture resistance 99 10
None 1.3:1 10 Silicone surfactant 1. 010
Alcohol-based lubricant 3.0 Addition amount of lubricant to epoxy resin is 1wt stearic acid-based lubricant:
No rust was observed, but small blisters were observed here and there on the coating film.

Depending on the application, it may be possible to use it without any interlayer.

Example 14 A magnet was produced in the same manner as Sample 51 except that the magnetic powder was changed to NdXFebalco6B6Gay anisotropic magnetic powder and a magnetic field of 15 koe was applied during compression molding. Table 1 characteristics
4. Note that sample 110 is a comparative example prepared using the same resin formulation as sample 9.

Table 14 Test Xy (BH)max Moisture resistance can be changed and high (BH)max can be achieved.

In addition, since the magnetic powder is coated, good moisture resistance can be achieved at the same time.

〔Effect of the invention〕

As described above, the bonded magnet according to the present invention has a high residual magnetic flux density, little thermal demagnetization, and excellent moisture resistance.
Industrially useful.

Claims (17)

[Claims] (1) Epoxy resin containing a curing agent adjusted to have a degree of curing of 20% or more by weight of 0.05% or more and 2.0%
R-Fe-B magnetic powder (R is one or more types including Y After kneading raw materials consisting of rare earth elements) at a temperature where the epoxy resin becomes liquid, curing treatment, crushing the mixture, uniformly mixing the amount of curing agent required for complete curing, pressing and curing. A method for manufacturing a bonded magnet characterized by: (2) The method for manufacturing a bonded magnet according to claim 1, further comprising a modified layer treated with a coupling agent at the interface between the R-Fe-B magnetic powder and the epoxy resin. (3) The method for manufacturing a bonded magnet according to claim 1, further comprising impregnating the bonded magnet with a resin, a low melting point metal, or water glass after curing. (4) The method for manufacturing a bonded magnet according to claim 1, wherein microcapsules containing powdered epoxy resin or liquid epoxy resin in an amount of 3 wt% or less based on the total amount of magnetic particles are mixed before pressing. (5) In the compression-molded bond magnet raw material made of R-Fe-B magnetic powder (R is one or more rare earth elements including Y) and epoxy resin, the average particle size of the R-Fe-B magnetic powder is 10
μm or more, and the average crystal grain size within the magnetic powder is 0.01 μm
0.5μm or more, and 0.05% or more by weight2
．． Magnetic powder for a bonded magnet, characterized in that substantially the entire surface of the magnetic powder is coated with an epoxy resin having a hardness of 0% or less and a hardness of 20% or more. (6) The magnetic powder for a bonded magnet according to claim 3, further comprising a modified layer treated with a coupling agent at the interface between the R-Fe-B magnetic powder and the epoxy resin. (7) In a compression molded bonded magnet made of R-Fe-B magnetic powder (R is one or more rare earth elements including Y) and epoxy resin, the average particle size of the R-Fe-B magnetic powder is 10 μm.
The average crystal grain size in the magnetic powder is 0.01 μm or more and 0.5 μm or less, and the amount of epoxy resin is 0.01 μm or more in weight ratio.
1. A bonded magnet characterized in that substantially the entire surface of magnetic powder is covered with an epoxy resin having a hardening degree of 20% or more and having an epoxy resin content of 0.05% or more and 2.0% or less. (8) The bonded magnet according to claim 7, further comprising a modified layer treated with a coupling agent at the interface between the R-Fe-B magnetic powder and the epoxy resin. (9) The coupling agent is γ-aminopropyl trimethoxysilane, N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, One type or a mixture of two or more types selected from γ-glycidoxypropyl trimethoxysilane and γ-N-phenylaminopropyl trimethoxysilane, and the amount added to the magnetic powder is 0.05% or more by weight. The bonded magnet according to claim 8, characterized in that the content is 1.0% or less. (10) The bonded magnet according to claim 7, characterized in that it is impregnated with a resin, a low melting point metal, or water glass. (11) 3wt added to the total amount of magnetic powder before pressing
8. The bonded magnet according to claim 7, wherein the epoxy resin adheres to each other magnetic particles coated with the epoxy resin. (12) R-Fe-B magnetic powder is R_vFe_wCo_
xB_yM_z (R is one or more rare earth elements including Y, M is Ga, Zn, Si, Al, Nb, Ta, W, Ti
, Zr, Hf, Mo, P, C, Cu, and one or more elements consisting of Ni and unavoidable impurities), 1
0≦v≦16, w=100-u-x-y-z, 0≦x≦30, 4≦y≦
8. The bonded magnet according to claim 7, wherein 11,0<z≦3. (13) The epoxy resin is bisphenol A epoxy,
8. The bonded magnet according to claim 7, wherein the bonded magnet is one type or a mixture of two or more types selected from novolak type epoxy, polyfunctional epoxy, and glycidyl type epoxy. (14) The bonded magnet according to claim 7, wherein the curing agent added during kneading is mainly diaminodiphenylmethane or 4,4' diaminodiphenylsulfone. (15) The epoxy resin contains one or a mixture of two or more selected from aluminum stearate, zinc stearate, calcium stearate, molten wax, silicone surfactants, and alcohol lubricants as a lubricant, and the epoxy resin The blending ratio to the resin is 1wt% or more10
8. The bonded magnet according to claim 7, wherein the bonded magnet is less than or equal to wt%. (16) The curing agent for complete curing is a powder of one type or a mixture of two or more types selected from an imidazole type curing agent, an amine type curing agent, or a trifluoroboric acid compound, and the average particle size is 30 μm or less. The bonded magnet according to claim 7, characterized in that: (17) Claim 7 characterized by being magnetically anisotropic.
Bonded magnets as described in .