JPH10321452A - Heat resistant bonded magnet and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat resistance by conducting forming and main thermosetting treatment using generally two-layer structure compound obtained by mixing and then subjecting rare earth magnet powder and resin part to primary thermosetting treatment, by adding again and mixing resin part to the roughly milled mixture and subjecting the resultant mixture to secondary thermosetting treatment. SOLUTION: In a heat resistant bond magnet manufacturing method for binding rare earth magnet powder with a resin part mainly consisting of thermosetting resin such as epoxy resin, molding and main thermosetting treatment are conducted using a generally two-layer structure compound obtained by mixing and then subjecting the magnet powder and the resin part to primary thermosetting treatment at a temperature of 100 to 160 deg.C, next adding again and mixing resin part to the mixed material, subjecting the resultant mixture to secondary thermosetting treatment at a temperature of 80 to 150 deg.. As a result, it is possible to prevent oxidization without decreasing the density of the rare earth bond magnet and to provide good heat resistance and high magnetic characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant rare-earth bonded magnet obtained by binding rare-earth magnet powder with a thermosetting resin or the like, and a method for producing the same.
The present invention relates to improvement in heat resistance of a bonded magnet formed by bonding -TB-Nb-based magnet powder with an epoxy resin or the like.

[0002]

2. Description of the Related Art Rare earth elements (R), Fe or Fe and C
R-T- composed of a transition metal (T) such as o and boron (B)
B-based permanent magnets have attracted attention as being excellent in cost performance and having high magnetic properties. Among them, isotropic bonded magnets manufactured in combination with resin have many advantages, such as mass production of near-net products and the ability to freely select the magnetization direction, and have established a wide market as easy-to-use magnets. It is getting. These bond magnets are expected to become increasingly important in the future for automobiles and home appliances mainly in the personal computer market, and their importance will increase in the future. The magnet powder for the RTB-based isotropic bonded magnet can be obtained by a super-quenching method. The resulting quenched flakes are heat-treated at an appropriate temperature to adjust the magnetic properties to obtain a powder for a bonded magnet. Then, after this magnet powder is surface-treated, it is mixed with a resin which is considered to be optimal according to the product application at an appropriate ratio to be compounded, and a molded body of a bonded magnet is obtained by a known compression molding method, injection molding method or the like. And heat curing. Epoxy resin is a typical thermosetting resin, but since epoxy resin softens or deteriorates at a temperature equal to or higher than the glass transition temperature like other resins, it is natural to use R-T-B bonded magnet products by compression molding using epoxy resin. The use of R-T-B bonded magnets made of epoxy resin is often used under relatively mild heat-resistant conditions (for example, a heat-resistant temperature of about 150 ° C or less) in consideration of the heat-resistant reliability of products. ing.

[0003]

The heat resistance of a bonded magnet is important. For example, a bonded magnet for a spindle motor for a CD-ROM of a personal computer has a high rotation speed and a low heat generation due to the recent increase in the speed of the CD-ROM. Since it is used in an environment where there is an increasing tendency, heat resistance that is stricter than before has been required. In addition to the heat resistance required for products using bonded magnets, in the process of incorporating bonded magnets into target products, automation lines such as reflow half are often incorporated in the assembly process to save labor, for example. The temperature of the bath usually rises to around 200 ° C., and the bond magnet may be thermally demagnetized under the influence of this rise in temperature.
Therefore, heat resistance to withstand this thermal demagnetization is required. In addition, heat resistance around 180 ° C. around the engine is required for automotive applications, and long-term reliability at high temperatures is important for bonded magnets for instruments in the front panel. As described above, improvement in heat resistance up to about 180 ° C. for an RTB-based bonded magnet is expected in a wide field, and the solution has been urgently needed.

[0004] Several elemental technologies are required to increase the heat resistance of bonded magnets. In the case of the magnet powder, the problem is that the new surface is exposed due to cracks of the compact generated during compression molding, and the exposed magnet powder is most oxidized. Oxidation of the magnet powder deteriorates the properties of the bonded magnet. This problem can be suppressed to some extent by grinding and adjusting the magnet powder to a predetermined particle size in advance. However, if the pulverized particle size is too fine, the bulk density becomes small and the density of the bonded magnet molded body is reduced. Further, it is important to suppress the reaction between the magnet powder and the resin part. That is, it is necessary to increase the density in order to enhance the magnetic properties of the bonded magnet. The compound for this purpose is made slightly viscous by adjusting the degree of curing of the resin portion in order to reduce the voids in the bonded magnet molding. However, a reaction occurs at the contact with the magnet powder at the time of the compression molding, particularly at the contact surface with the new surface generated at the time of the compression molding, and the magnetic characteristics are reduced. If the heat curing is performed in an inert gas atmosphere, the oxidation of the magnet powder and the progress of the reaction with the resin can be suppressed, but when the bonded magnet product is used in the atmosphere, the reaction or oxidation will eventually progress. Conversely, it is possible to reduce the contact with the new surface by increasing the hardness before compression molding at the expense of the viscosity of the compound, but in this case, the bond magnet can reduce the irreversible demagnetization rate at high temperatures. Due to the low density, the magnetic properties deteriorate. This problem is caused not only by the RTB-based isotropic bonded magnet, but also by an RTB-based anisotropic bonded magnet or an isotropic or anisotropic filled with other known rare earth magnet powders. Rare earth bonded magnets also exist. As described above, conventionally, it has been extremely difficult to provide heat resistance while maintaining high magnetic properties.

[0005] In view of the above-mentioned conventional problems, an object of the present invention is to provide a rare earth bonded magnet having high magnetic properties and excellent heat resistance, as well as an RTB-based and RTB-Nb-based magnet. It is to obtain a heat-resistant bonded magnet stably and easily.

[0006]

Means for Solving the Problems The present inventor relates to a heat-resistant bonded magnet filled with rare earth magnet powder (for example, RTB-Nb-based magnet powder, etc.), and hardens the inside of the resin portion of the compound before compression molding. The resin composition on the front side has a low viscosity (hardening degree) with a substantially two-layer resin structure to maintain the magnetic properties without decreasing the density of the molded body of the bonded magnet and to have high heat resistance. Have been found, and the present invention has been made. That is, the present invention relates to a method for manufacturing a heat-resistant bonded magnet in which a rare-earth magnet powder is bound by a resin portion mainly composed of a thermosetting resin such as an epoxy resin, wherein the magnet powder and the resin portion are kneaded at 100 to
A primary heat-curing treatment is performed at 160 ° C., and then the kneaded material is roughly added and then kneaded by additionally adding the resin portion to the roughly kneaded material.
This is a method for manufacturing a heat-resistant bonded magnet in which molding is performed using a compound having a substantially two-layer structure obtained by performing a secondary heat-curing treatment at 80 to 150 ° C., and the main heat-curing treatment is performed. The primary heat curing temperature is set to 100 to 160 ° C. in order to advance the degree of curing of the resin portion inside the compound having a substantially two-layer structure at this stage. The reason why the resin portion is additionally added after the coarse pulverization is to prevent the resin portion constituting the outer peripheral side from undergoing the primary heat curing treatment. After molding using a compound that does not perform primary and secondary heat-curing treatments, and then performing main heat-curing to produce a bonded magnet, the resin part of the compound is cured and the viscosity is lost. Become. That is, the voids of the bonded magnet increase, and the magnetic properties and mechanical strength decrease. If the molding pressure is increased to increase the density, the compound will break during compression molding,
Because the new surface is newly exposed, it is strongly affected by oxidation. In view of this problem, in the present invention, the compound after the first heat curing is coarsely pulverized, and then the resin portion is added again to cover the surface of the compound particles with a low-viscosity resin and kneading is performed. 80-150 after this kneading
A second heat-curing treatment is performed at a temperature of ° C. to adjust the viscosity of the resin portion coated on the surface of the compound particles to facilitate powder feeding during compression molding. If the temperature is lower than 80 ° C., the degree of curing of the outer peripheral resin portion is insufficient, and if the temperature exceeds 150 ° C., the curing proceeds too much, the effectiveness of the two-layered compound is lost, and the density of the bonded magnet decreases in any case. It is not preferable.

[0007] At least one of the above-mentioned primary heat-curing treatment, secondary heat-curing treatment, and main heat-curing treatment, more preferably, the entire process is performed at 180 ° C. in an atmosphere containing 10 ppm to a substantial amount of oxygen in air. The irreversible demagnetization rate up to this point can be improved as compared with the conventional case. That is, according to the present invention, good heat resistance is obtained when the heat curing treatment twice and the heat curing treatment of the compact after compression molding are performed in an atmosphere containing 10 ppm or more of oxygen (the upper limit is in the air). Property is obtained. The conventional heat-curing treatment is performed in an argon gas, a nitrogen gas, a vacuum, or the like in order to prevent the influence of oxidation.However, in the present invention, which is intended to obtain a bonded magnet having heat resistance, the heat-curing treatment is performed with oxygen. It was concluded that conducting in the presence of a suitable amount was more effective in obtaining long-term heat-resistant reliability. When the oxygen content in the heat-curing atmosphere is less than 10 ppm, the bonded magnet properties at room temperature are high, but under the environment exposed to an oxidizing atmosphere at 180 ° C. for a long time, the influence of oxidation is large and the magnetic properties and the irreversible demagnetization rate are significantly reduced.

Further, the present invention provides a method for binding a rare earth magnet powder with a resin portion substantially comprising a mixture of a liquid glycidylamine type epoxy resin and an aromatic amine curing agent,
A heat-resistant bonded magnet in which the total amount of the resin part is 0.1 to 8% by weight based on the magnet powder. ADVANTAGE OF THE INVENTION According to this invention, when a well-known rare earth magnet powder is used, good heat resistance and high magnetic characteristics are provided.

Further, the present invention relates to an R-T-B-based alloy containing R ₂ T ₁₄ B as a main phase (R is one or more of rare earth elements including Y, for example, Nd + Dy or N
It can be composed of d + Pr or Nd + Dy + Pr. T is a magnetic powder composed of Fe or Fe and Co, and B is boron) bound with a resin part substantially composed of a mixture of a liquid glycidylamine type epoxy resin and an aromatic amine curing agent. A heat-resistant bonded magnet having a total amount of 0.1 to 8% by weight based on the magnet powder. The magnet powder, R _u T _100-UV composition in atomic percentages
B _V (R is one or more rare earth elements including Y, T is Fe or Fe and Co), and u = 8
１７17 atomic%, and v = 4-8 atomic%. When u is less than 8 atomic%, αFe is generated to make the R ₂ T ₁₄ B main phase unstable, and when it exceeds 17 atomic%, the saturation magnetization is significantly reduced. Therefore, u is preferably 8 to 17 atomic%. When v is less than 4 atomic%, the intrinsic coercive force (iHc) is significantly reduced, and when it exceeds 8 atomic%, the residual magnetic flux density (Br) is significantly reduced. Therefore, v is preferably 4 to 8 atomic%. The substitution amount of Co in the transition metal T is preferably 30 atomic% or less. If it exceeds 30 atomic%, the Curie point is improved, but the magnetic anisotropy constant of the main phase is reduced, and it is difficult to obtain a high iHc.

Further, the present invention relates to a method for preparing R _X T
_100-xyz B _y Nb _z (R is one or more of rare earth elements including Y, T is Fe or Fe and Co, B
Is boron and Nb is niobium), and x = 8 to 1
5, R-T- in the range of y = 4 to 8, z = 0.1 to 2
The B-Nb-based magnet powder is bound with a resin portion substantially composed of a mixture of a liquid glycidylamine-type epoxy resin and an aromatic amine curing agent, and the total amount of the resin portion is 0.1% with respect to the magnet powder. The heat-resistant bonded magnet is 1 to 8% by weight. It is preferable that R of the magnet powder is 8 to 15 atomic%. If R is less than 8 at%, α-Fe is generated to make the R ₂ Fe ₁₄ B phase unstable, and if it exceeds 15 at%, the saturation magnetization is significantly reduced. If Nb is less than 0.1 at%, the effect of improving the heat resistance by suppressing the coarsening of the crystal grains is not recognized, and if it exceeds 2.0 at%, the saturation magnetization is significantly reduced. If B is less than 4 atomic%, it is difficult to obtain a high intrinsic coercive force (iHc). If it exceeds 8 atomic%, the residual magnetic flux density (Br) decreases. The substitution amount of Co in the transition metal T is preferably 30 atomic% or less as described above. The bonded magnet of the present invention has an R-T-
The B-Nb-based magnet powder is bound by a characteristic resin portion, and has a feature that the irreversible demagnetization rate described later can be reduced to 5% or less.

Based on the fact that the glass transition temperature of the conventional powdery epoxy resin is at most around 150 ° C., the present inventors have conducted extensive studies using various liquid epoxy resins, and have found that the kneading and the control of the degree of curing are easy. A liquid glycidylamine type epoxy resin having a glass transition temperature of 240 to 250 ° C. lower than the Curie temperature of the RTB-Nb-based magnet powder and sufficiently high as a binder resin component; It has been found that the use of a resin part composed of a mixture with an amine curing agent is effective for improving heat resistance. And, when the total amount of the resin part is 0.1 to 8% by weight based on the magnet powder, 180 can be provided for practical use.
It has been found that good heat resistance up to ℃ and high magnetic properties can be obtained. If the total resin content of the resin part is less than 0.1% by weight, compounding is difficult, and if it exceeds 8% by weight, the density of the bonded magnet is significantly reduced. The mixing ratio of the liquid glycidylamine type epoxy resin and the aromatic amine curing agent can be appropriately selected in consideration of a desired degree of curing.

The heat-resistant bonded magnet of the present invention has a substantially two-layer structure in which a resin portion having a lower degree of curing than the resin portion binding the magnet powder in the compound before compression molding covers the surface. This is a heat-resistant bonded magnet which has a density sufficient for a bonded magnet obtained through molding to be practically used, and at the same time, suppresses the progress of oxidation of the magnet powder and maintains high magnetic properties. Since the inside of the compound having a substantially two-layer structure is hard on the inner side and rich on the outer peripheral side (the degree of hardening is lower than that of the resin part on the inner side), it is possible to increase the density at the time of molding the bonded magnet. Finally, the magnetized bond magnet having a permeance coefficient of 2 was magnetized at room temperature with a pulsed magnetic field of 50 kOe, and the amount of magnetic flux was measured at 20 ° C. The irreversible demagnetization rate was evaluated by measuring the amount of magnetic flux when the temperature returned to
% Or less, and has good heat resistance. Further, the density of the heat-resistant bonded magnet of the present invention is 5.0 g / cc or more,
In addition, the maximum energy product measured at 20 ° C. achieves 5 MGOe or more.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples. (Examples 1 to 3) N in atomic% as bonded magnet powder
with d _11.5 Fe _80.7 B ₆ MQI composition of Nb _1.8 (magnetic quenching International) made of MQP-O material was ground to an average particle size of 110μm at a bantam mill. The MQP-O material before pulverization is a magnet powder having an average crystal grain size of 0.01 to 0.5 μm having a high coercive force that can withstand practical use after being subjected to a super-quenching method, pulverization and heat treatment. The crushed particle size of the magnet powder by a bantam mill can be appropriately selected in the range of 1 to 1000 μm. To this pulverized powder, a silane coupling material manufactured by Nippon Unicar Co., Ltd. was added in an amount corresponding to 0.25% by weight to perform a surface treatment. Next, a liquid glycidylamine type epoxy resin (E630) manufactured by Yuka Shell Co., Ltd. and DDS (diaminodiphenylsulfone) as an aromatic amine curing agent
(A weight ratio of E630: DDS =
100: 43.2) was weighed so that the total amount was equivalent to 2.6% by weight relative to the surface-treated powder, and the resin mixture was divided into two portions and added to the magnetic powder or the kneaded material. Knead with a shaft kneader. First, in the first kneading, 80% by weight of the total resin part is kneaded with the magnet powder,
The obtained kneaded material was subjected to a primary heat curing treatment under the conditions shown in Table 1. The primary curing and the secondary curing in Table 1 are primary heat curing treatments,
This represents the next heat curing treatment. Subsequently, at the time of the second kneading, the remaining 20% by weight of the total amount of the resin part was added and kneaded.
Next, a heat curing treatment was performed, and then compression molding was performed without a magnetic field in a predetermined molding die. The obtained isotropic bonded magnet molded body is subjected to a main heat-curing treatment (a process of holding at 180 ° C. × 1 hour in the air, holding at 190 ° C. × 4 hours, and cooling to room temperature), and performing the heat-resistant bonded magnet of the present invention. I got The density of the bonded magnet, the magnetic properties at 20 ° C., and the irreversible demagnetization rate (α) were measured after finishing the bonded magnet into a cylindrical sample having a permeance coefficient of 2 (thickness / diameter = 0.7). The irreversible demagnetization rate (α) is determined by measuring the initial magnetic flux measured at 20 ° C. after magnetizing the sample with a pulse magnetic field of 50 kOe at room temperature, and subsequently cooling the sample to 180 ° C. × 1000 hours in the atmosphere and cooling to 20 ° C. It is a magnetic flux amount change rate obtained from the measured magnetic flux amount, and was calculated by the following equation. Irreversible demagnetization rate (α) = (initial magnetic flux at 20 ° C-180 ° C in air)
× The amount of magnetic flux of the sample returned to 20 ° C. after heating for 1000 hours) ÷
(Initial magnetic flux at 20 ° C.) × 100 (%). The results are shown in Table 1. The magnetic properties, density, and irreversible demagnetization rate (α) in each of the following examples and comparative examples were evaluated in the same manner as in Example 1.

Comparative Examples 1 to 5 A liquid glycidylamine type epoxy resin (E630) manufactured by Yuka Shell Co., Ltd. and a DDS (diamino) Diphenylsulfone) in a total amount of 2.6% by weight relative to the magnet powder (E6 in weight ratio).
30: DDS = 100: 43.2)
It was kneaded only once with a twin-screw kneader. After kneading, only the primary heat curing treatment shown in Table 1 was performed. The obtained kneaded product was directly compression-molded into a predetermined mold without a magnetic field to obtain an isotropic bonded magnet molded product. Thereafter, the main heat-curing treatment was performed in the same manner as in Example 1, and the results of evaluating each characteristic are shown in Table 1. (Comparative Example 6) The same process as in Example 1 was performed except that the secondary heat curing treatment was performed at 160 ° C for 1 hour to obtain an isotropic bonded magnet. Table 1 also shows the results of evaluating the properties of this product.

[0015]

[Table 1]

As shown in Table 1, in Examples 1 to 3 in which kneading was performed twice and primary and secondary heat curing treatments were performed, α was 5%.
And the maximum energy product (BH) max is also 6MG
Oe is exceeded. On the other hand, in Comparative Examples 1 to 3, the primary heat curing treatment temperature was low, so that the curing of the resin portion was slow, the density and Br were increased, and the maximum energy product exceeded 8 MGOe. However, iHc is slightly lower than in Examples 1 to 3, and α is particularly large. This is probably because the resin portion and the magnet powder reacted during the main heat curing. Further, in Comparative Examples 4 and 5, high iHc was obtained and α was made 5% or less, but the density was low and the maximum energy product was 5MGOe.
Is below. In addition, the secondary heat curing temperature is 150
In the case of Comparative Example 6 in which the temperature was higher than 0 ° C., the curing was excessively progressed and many gaps were formed in the bonded magnet, and the density of the bonded magnet was lowered.

The results of examining the change in magnetic properties and irreversible demagnetization rate due to the change in the total amount of resin composed of a mixture of a liquid glycidylamine type epoxy resin and an aromatic amine curing agent will be described below. (Examples 4 to 7, Comparative Example 7) As shown in Table 2, the total amount of the resin portion was changed and the second heat curing treatment was performed at 115 ° C. ×
A bonded magnet was prepared and evaluated in the same manner as in Example 1 except that the time was changed to 1 hour.

[0018]

[Table 2]

From Table 2, it can be seen that in Examples 4 to 7, the density and magnetic properties gradually decreased because the proportion of the magnet powder in the bonded magnet decreased with the increase in the total amount of the resin part. Α is as good as in Examples 1 to 3 above. In addition, if the lower limit of the total amount of the resin part is 0.1% by weight or more, the resin can be practically used.

Next, the result of examining the effect of the heat-curing atmosphere will be described. (Examples 8 to 9 and Comparative Examples 8 to 10) A bonded magnet molded body prepared in the same manner as in Example 5 except for the manufacturing process immediately before the main heat curing treatment was prepared. Next, only the atmosphere at the time of the main heating and curing was in the air (Example 8), in an argon gas having an oxygen content of 50 ppm (Example 9), in a vacuum having an oxygen content of less than 10 ppm (Comparative Example 8), and in an argon gas. (Comparative Example 9) and 180 ° C. × 1 hour in nitrogen gas (Comparative Example 10)
Subsequently, a main heat curing treatment of cooling to room temperature after heating and holding at 190 ° C. × 4 hours was performed. The results are shown in Table 3.

[0021]

[Table 3]

From Table 3, at 20 ° C., those of Comparative Examples 8 to 10 have slightly higher magnetic characteristics than those of Examples 8 and 9. However, α was determined in Examples 8 and 9 in Comparative Examples 8 to 10.
This indicates that the bonded magnet of the present invention has good heat resistance. In other words, when the main heat-curing treatment is performed in a vacuum containing less than 10 ppm of oxygen, in argon, or in a nitrogen gas, the magnetic properties at room temperature are high, but oxidization that is exposed to a high temperature for a long time in the air is strongly received. This indicates that the magnetic properties are oxidized under the environment and the magnetic properties are rapidly deteriorated. When the oxygen content of the main heat-curing atmosphere is 10 ppm or more, substantially the same results as those of Examples 8 and 9 can be obtained. In the heat-resistant bonded magnet of the present invention, the lower limit of the oxygen content of at least one of the first heat-curing treatment, the second heat-curing treatment and the main heat-curing treatment is from 10 ppm or more to the upper limit is the oxygen content equivalent to the atmosphere. It can be obtained by setting the atmosphere.

Next, FIG. 1 schematically shows a cross-sectional structure of a principal part of an ideal compound for a heat-resistant bonded magnet of the present invention. The magnet powder is bonded to a first-layer resin portion to form an inner compound, and has a substantially two-layer structure in which an outer peripheral side is covered by a second-layer resin portion. By using the compound having this structure, a heat-resistant bonded magnet having good heat resistance up to 180 ° C. and high magnetic properties can be obtained as described above.

In the above embodiment, the isotropic RTB-Nb
Rare earth bonded magnet filled with system magnet powder is described,
The same effect can be obtained in a rare-earth bonded magnet filled with isotropic or anisotropic RTB-based magnet powder and a rare-earth bonded magnet filled with anisotropic RTB-Nb-based magnet powder. Can be expected. Furthermore, these magnet powders are not only manufactured using the super-quenching method, but also have an average recrystallized particle size manufactured using the HDDR method of 0.01 to 0.5 μm.
m and the average particle size of the magnet powder is 1 to 1000 μm. Furthermore, the same effects as described above are expected for rare-earth bonded magnets filled with other known rare-earth magnet powders. Specifically, SmCo ₅ magnet powder, Sm ₂ T
M ₁₇ magnet powder (TM = Co + Fe + Cu + Zr or C
o + Fe + Cu + Hf), Nd (+ Pr) -Fe-N magnet alloy powder having a structure of ThMn ₁₂ type compound, Th
Examples include Sm-Fe-N-based magnet alloy powder and exchange spring magnet powder having a structure of ₂ Zn ₁₇ type compound and / or TbCu ₇ type compound.

[0025]

According to the present invention, the compound, which is a raw material for forming a rare-earth bonded magnet, has a substantially two-layer structure, so that the oxidation can be suppressed without lowering the density of the rare-earth bonded magnet, and the temperature up to 180.degree. A heat resistant rare earth bonded magnet having excellent heat resistance and high magnetic properties and a method for manufacturing the same can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a compound which is a raw material for forming a heat-resistant bonded magnet of the present invention.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI // C22C 38/00 303 H01F 1/08 A

Claims (7)

[Claims] 1. A method for manufacturing a heat-resistant bonded magnet comprising a rare-earth magnet powder bound by a resin portion mainly composed of a thermosetting resin, comprising: kneading the magnet powder and a resin portion; The kneaded product is then roughly pulverized, and the above resin portion is again added thereto and kneaded. Then, the kneaded product is subjected to a second heat-curing treatment, and molded using a compound having a substantially two-layer structure. And a method for producing a heat-resistant bonded magnet, which comprises performing a main heat curing treatment. 2. The method according to claim 1, wherein the first heat curing treatment is performed.
A method for producing a heat-resistant bonded magnet, wherein at least one of the secondary heat-curing treatment and the main heat-curing treatment is performed in an atmosphere containing 10 ppm to a substantial amount of oxygen in the atmosphere. 3. The method according to claim 1, wherein the first heat-curing treatment is performed at 100 to 160 ° C., and the second heat-curing treatment is performed at a temperature of 8 ° C.
A method for producing a heat-resistant bonded magnet performed at 0 to 150 ° C. 4. The rare earth magnet powder is bound by a resin portion substantially composed of a mixture of a liquid glycidylamine type epoxy resin and an aromatic amine curing agent, and the total amount of the resin portion is 0 to the magnet powder. 0.1 to 8% by weight. 5. An RTB-based alloy having R ₂ T ₁₄ B as a main phase (R is one or more of rare earth elements including Y, T is Fe or Fe and Co, B Is bonded with a resin part substantially consisting of a mixture of a liquid glycidylamine type epoxy resin and an aromatic amine curing agent, and the total amount of the resin part is 0 to the magnet powder. 0.1 to 8% by weight. In 6. atomic percentages _{R X T 100-Xyz B y} Nb
_z (R is one or more of the rare earth elements including Y, T is Fe or Fe and Co, B is boron, Nb is niobium), x = 8 to 15, y = 4-8,
The RTB-Nb-based magnet powder in the range of z = 0.1 to 2 is bound with a resin part substantially consisting of a mixture of a liquid glycidylamine type epoxy resin and an aromatic amine curing agent. A heat-resistant bonded magnet, wherein the total amount of the resin part is 0.1 to 8% by weight based on the magnet powder. 7. A heat-resistant bonded magnet comprising a rare earth magnet powder bound by a resin portion mainly composed of a thermosetting resin,
The maximum energy product at 0 ° C. is 5 MGOe or more, the density is 5.0 g / cc or more, and the heat-resistant bonded magnet formed to have a permeance coefficient of 2 is magnetized with a pulse magnetic field of 50 kOe. 10
Irreversible demagnetization rate when returning to 20 ° C after holding for 00 hours is 5
% Or less.