JPH0541328A - Manufacture of flexible bonded magnet - Google Patents

Abstract

PURPOSE:To perform a high-temperature heating on a sheetlike magnet material without generating a trouble, such as an air forming, by a method wherein after the sheetlike magnet material is preheated under specified conditions, a heat treatment is performed on the material. CONSTITUTION:A sheetlike magnet material obtained by a rolling process is preheated and thereafter, a heat treatment is performed on the material. The preheating is for making water content, gas or the like being contained unavoidably in the material diverge to the outside by a preheating process. Temperature conditions and time conditions in this preheating process are respectively set on the conditions of 30 to 70 deg.C and the conditions of 6 hours or longer. At this time, the air is previously restrained from being caught in the material as much as possible. On the other hand, temperature conditions and time conditions in the heat treatment process subsequent to the preheating are respectively set on the conditions of 125 to 180 deg.C and the conditions of 60 to 80 minutes and the material is left to stand in a heating device formed by laminating vertically iron plates in three steps or a constant temperature bath consisting of a vapor can or the like, for example, for 60 to 180 minutes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flexible bonded magnet incorporated in a rotating electric machine or the like.

[0002]

2. Description of the Related Art Conventionally, various bond magnets have been developed which are relatively inexpensive and have good magnetic characteristics. For example, Japanese Unexamined Patent Publication No. 59-2111549 proposes a bonded magnet obtained by solidifying rare earth-iron-boron magnetic powder with an adhesive, and Japanese Unexamined Patent Publication No. 61-17436.
Japanese Unexamined Patent Publication No. 4 (1994) proposes a plastic magnet obtained by mixing misch metal-transition metal-boron magnetic powder with a binder. Further, JP-A-63-274114 and JP-A-63-287003 propose a plastic magnet using a mixture of rare earth magnet powder and ferrite magnet powder, and JP-A-2-22803. Proposes a bonded magnet formed by mixing rare earth magnet powders. Also, JP-A-63-181649
The publication discloses a flexible magnet using ferrite magnetic particles.

Such a bonded magnet is made by dispersing magnetic powder in a binder resin by kneading, and its manufacturing method is described in, for example, JP-A-60-164313. According to the manufacturing method disclosed in this publication, the magnetic powder and the silane coupling agent are mixed little by little in the binder resin, and kneading is performed using a mixing roll. The obtained kneaded product is once crushed and then rolled into a sheet. The sheet-shaped magnet material is subjected to heat treatment with water vapor, whereby strains generated in the rolling process are removed or vulcanization is performed.

[0004]

However, when the above-described heat treatment is applied to a flexible bonded magnet, air bubbles may be generated in the bonded magnet, and it may not be possible to commercialize the bonded magnet. This is because moisture, gas, and the like, which are inevitably contained in the bonded magnet, expand due to the heat treatment, and as a result, a dimensional error in the plate thickness direction occurs during cutting, or magnetization is performed. There is a risk of causing problems such as popping-out of the magnet when it is hit.

Therefore, an object of the present invention is to provide a method for manufacturing a flexible bonded magnet, which is capable of favorably heat-treating a flexible bonded magnet.

[0006]

In order to achieve the above object, a method for producing a flexible bonded magnet according to the present invention is a flexible bond in which magnetic powder is dispersed in a binder resin having flexibility. In the magnet manufacturing method, at least
The step of kneading the magnetic powder and the binder resin, the step of rolling the kneaded product obtained in the above step into a sheet, the step of preheating the sheet-shaped magnet material under predetermined conditions, and the preheating The method includes a step of subjecting the sheet-shaped magnet material to a heat treatment, and a step of cutting the sheet-shaped magnet material after the heat treatment.

[0007]

In the means having such a structure, the sheet-shaped magnet material is preheated before the heat treatment step is started, and the sheet-shaped magnet material is unavoidably included in the sheet-shaped magnet material by this preheating step. Moisture, gas, etc. that have been dispersed are released to the outside in advance. Therefore, in the heat treatment process, the generation of bubbles is suppressed.

A more specific structure of the above means is described in
The case where a transition metal-boron magnetic powder is used will be described as an example. First, a predetermined magnetic powder is obtained by the ultraquenching method.
The jet casting method is an example of the ultra-quenching method. In this jet casting method, an ingot-shaped magnetic alloy is housed in a pan and the alloy is melted by a high frequency wave or the like in an inert environment. The magnetic alloy in a molten state is poured into a pool of water with a nozzle and dropped through a nozzle onto a rotating wheel. The rotating wheel is cooled by water, where rapid cooling takes place. The rapidly cooled magnetic alloy is solidified into ribbon-shaped magnetic powder, drops downward, and is collected in a container.

Here, when the rare earth-transition metal magnetic powder is used, one or more kinds of lanthanoids are used as the rare earth, and the transition metals are Fe, Co, and
One or more of Ni are used. The rare earth-transition metal magnetic powder can contain boron to form a rare earth-transition metal-boron (RTB) magnetic powder. Specifically, Nd-Fe-B based magnetic powders are Nd-Fe-B, Nd-Fe-Co-B, (Nd, Pr).
-Fe-B, (Nd, Pr) -Fe-Co-B and the like are used, and (Ce, La) -Fe-B magnetic powder is (Ce, L).
a) -Fe-B, (Ce, La) -Fe-Co-B, MM-Fe-
B, MM-Fe-Co-B, etc., and Sm-Co
Examples of magnetic powders include Sm-Co, Sm-Co-Fe, Sm-
Co-Mn or the like is used.

Next, as shown in FIG. 1, the magnetic powder is weighed so as to be 55 to 96% by weight based on the whole magnet. The magnetic powder content is set to 96% by weight or less with respect to the entire magnet because when the ratio of the magnetic powder is higher than 96% by weight, the amount of the binder with respect to the magnetic powder becomes insufficient and the magnetic force of the magnet itself. This is because the strength of the binder is reduced and the magnet collapses, or the magnet becomes too hard and lacks flexibility, so that it cannot be incorporated into a product. On the other hand, the magnetic powder is set to 55% by weight or more based on the whole magnet because if the ratio of the magnetic powder is less than 55% by weight, the magnetic force becomes insufficient and the usefulness of the rare earth magnetic powder for high magnetic force is lost. Is. When the magnetic powder is 92% by weight or more with respect to the entire magnet, the filling rate of the magnetic powder can be increased to prevent the magnet from being deformed and the rigidity of the magnet required for incorporating into the product can be obtained.

At this time, the rare earth-transition metal-boron system (R
In the case of using -TB) magnetic powder, it is preferable to pulverize the magnetic powder to a fine powder having a median diameter of 78 µm or less, for example, 42 µm, in order to obtain the filling rate. The magnetic powder is adjusted by using a ball mill, a roll or the like.

In particular, when the required magnetic force of the magnet is set to be small, the amount of the magnetic powder to be charged may be too small to reach a predetermined filling rate. In that case, non-magnetic powder such as white carbon may be used as a reinforcing material in a binder (described later) together with the magnetic powder. By using such a mixed filler, it is possible to increase the so-called filler filling rate in the magnet to a required value, thereby improving the deformability of the magnet and increasing the rigidity of the magnet. The range of the filling rate at this time is 73 to 50% by volume with respect to the total amount of the filler including the magnetic powder and the mixed filler, and particularly when the rare earth-transition metal-boron (RTB) magnetic powder is used. , 71 to 13% by volume, and the range of the mixed filler is 60 to 2% by volume.

As the non-magnetic mixed filler, chemically or physically stable powder such as talc, carbon black, carbon fiber or ferrite powder can be used in addition to the white carbon described above. The particle size of the mixed filler is 70 μm or less in median diameter.

Further, when Nd-Fe-B type magnetic powder is used as the magnetic powder, it is preferable to use (Ce, La) -Fe-B type magnetic powder instead of the above-mentioned non-magnetic mixed filler. This is because the magnet using the Nd-Fe-B system magnetic powder is difficult to vulcanize (described later) and it is difficult to obtain the required rigidity. Rare earths that are easy to vulcanize-
When a transition metal-boron (R-T-B) magnetic powder is mixed, vulcanization is promoted to the inside of the magnet, the rigidity of the magnet is increased, and the deformation of the magnet can be prevented. Mixed rare earth-transition metal-boron system (RT-
B) As magnetic powder, (Ce, La) -Fe-B, misch metal-Fe-B, etc. can be adopted.

As for the mixing ratio of the magnetic powders, any ratio can be adopted as long as the residual magnetic flux density Br is 6300 G or less. In particular, Nd-Fe-
When the B magnetic powder and the (Ce, La) -Fe-B system magnetic powder are mixed, the (Ce, La) -Fe-B system magnetic powder is blended in an amount of 5% by weight or more with respect to the entire magnetic powder. If so, it is possible to obtain a predetermined rigidity.

Next, a predetermined amount of rust preventive agent and epoxy main agent are mixed to form an oxide film, an epoxy resin film and a rust preventive film (film forming step). That is, first, an inert gas is injected into the mixing device, and the air in the mixing device is gas-substituted so that the oxygen concentration becomes 0.08 to 3%. A ball mill, a V type blender, a double cone type blender or the like is used as the mixing device. As the inert gas, argon gas (Ar), nitrogen gas (N _2), carbon dioxide (CO
₂ ) etc. are used.

The rare earth-transition metal magnetic powder, the epoxy main agent and the rust preventive agent are charged into the mixing apparatus thus gas-replaced, and the mixing is carried out for about 2 hours. In the mixing, first, a small amount of oxygen remaining in the mixing device forms an oxide film on the surface of the magnetic powder, and further an epoxy resin film and a rust preventive film are formed thereon. The oxygen concentration is set to 0.08% to 3% because if the oxygen concentration is less than 0.08%, the oxide film cannot be formed or the formed oxide film is extremely thin. This is because if the concentration exceeds 3%, there is a danger of ignition due to oxygen.

As the epoxy main agent, one or more of bisphenol-based, phenoxy-based, novolac-based, polyphenol-based, polyhydroxybenzene-based or derivatives thereof are used, and rust inhibitor sorbitan monooleate. And a mixture of mineral oil or synthetic oil.

The magnetic powder on which the oxide film, the epoxy resin film and the rust preventive film are formed is taken out and weighed.
It is kneaded with a flexible binder resin by a pressure kneader for several minutes (kneading step). At this time, a curing agent and a curing accelerator for the epoxy resin are added. The curing agent and the curing accelerator are added at this stage in order to prevent the magnetic powder from being hardened immediately after the mixture of the magnetic powders is taken out. Through such a kneading step, the rare earth-transition metal magnetic powder is almost uniformly dispersed in the flexible binder resin.

As the flexible binder resin at this time, natural rubber (NR) and isoprene rubber (I
R), budadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene rubber (EPR), ethylene-vinyl acetate rubber (EV)
A), nitrile rubber (NBR), acrylic rubber (A
R), urethane rubber (UR) and the like are used alone or in combination of two or more. That is, these binder resins are so-called ternary rubbers, and have a non-polar rubber component (eg IIR) and a highly polar rubber component (eg NB).
R) is a rubber component containing halogen (for example, CR)
Are mixed well through. A rubber component having no polarity has difficulty in oil resistance and weather resistance, and a rubber component having a strong polarity is extremely hard and requires addition of an extender oil or a plasticizer. Therefore, if both rubber components are mixed through a halogen-containing rubber component, the rubber components that make up the difficulties of the respective rubber components are easily mixed, and the oil resistance and weather resistance are improved. is there.

As the rubber component containing halogen, chloroprene rubber (CR), hypalon (CSM),
Those containing chlorine such as chlorinated polyethylene are used alone or in combination of two or more. In this case, the halogen-containing rubber component should be set to 15% by weight or less, preferably 6.2% by weight or less, based on the weight of the entire binder resin. When the rubber component containing halogen exceeds 15% by weight of the total weight of the binder resin, chlorine gas (Cl ₂ ) or hydrochloric acid gas (HCl) is generated. For example, in the case of a motor, a commutator This is because it causes corrosion, rust of magnets and core rust. Also, the rubber component containing halogen is 6.2% of the total weight of the binder resin.
If the content exceeds 50% by weight, the magnet becomes too hard and becomes brittle, lacking flexibility, making it impossible to incorporate it in the product, or easily breaking by external force or its own magnetic force. Because.

Examples of the curing agent include polyamines such as aliphatic polyamines and aromatic polyamines, acid anhydrides such as phthalic anhydride, polyamide resins, polysulfide resins, amine complexes such as boron trifluoride, and synthetic resins such as phenolic resins. One kind or two or more kinds of the initial condensate or derivatives thereof are used. As the curing accelerator, amines such as trisdimethylaminomethylphenol, imidazoles such as 1-isobutyl-2-methylimidazole, and one or more of these derivatives are used.

In this kneading step, the pressure kneader is cooled, and kneading is carried out at a temperature of 95 ° C. or lower, preferably 50 to 60 ° C. With this temperature setting,
The risk of ignition in the kneading process is avoided. That is, if kneading is carried out at a temperature higher than 95 ° C, there is a danger of ignition due to heat generation, and at 40 ° C or lower, rubber is not plasticized sufficiently and sufficient kneading cannot be carried out.

The magnet material as a kneaded product obtained by the above kneading step is taken out from the pressure type kneader and immediately divided into small lots of 10 kg or less. Each of these subdivided magnet materials is enclosed and stored in an airtight container, and is left as it is until the temperature of the magnet material drops to room temperature (preservation step). The heat release during this storage step avoids the risk of ignition.

The magnet material as a kneaded material, which has been sufficiently radiated by the above-mentioned storage step, is taken out and has a particle size of 5 mm.
It is crushed into the following sizes (crushing process). This crushing process is performed using argon gas (Ar), nitrogen gas (N ₂ ), carbon dioxide gas (CO
₂ ) is performed under cooling by the flow of an inert gas such as
The temperature condition is set to 95 ° C. or lower. A rotary blade or the like is used for crushing. That is, in this crushing step, air cooling with an inert gas is performed, and crushing can be performed in the atmosphere.

Then, the pulverized material obtained in the pulverizing step is rolled by a roll or the like to obtain a sheet-shaped bond magnet (sheet forming step). At this time, the surface temperature of the rolling roll is maintained at 20 to 80 ° C., whereby the tensile strength of the sheet-shaped magnet material is favorably maintained in the rollable range and the oxidation of the magnetic powder is suppressed. The deterioration of magnetic characteristics is prevented.

In this case, particularly in a magnet using a rare earth-transition metal-boron (R-T-B) magnetic powder, a filler such as magnetic powder so that the density after rolling is 4.9 to 5.8. It is necessary to adjust the filling rate. This is because if the density of the magnet is smaller than 4.9, the rigidity of the magnet will be insufficient and it will be easily deformed, making it impossible to incorporate it in the product. If it exceeds, brittleness of the magnet becomes large and cracks and the like are likely to occur, which causes a problem such as the magnet collapsing due to magnetization.

Further, the sheet-shaped magnet material obtained by the above rolling step is preheated and then heat-treated. This is because the preheating step causes the moisture, gas, and the like that are unavoidably contained in the sheet-shaped magnet material to diffuse to the outside.
The temperature condition and time condition in this preheating step are 30 ° C.
It is set to ˜70 ° C. and 6 hours or more. At this time, entrapment of air in the sheet-shaped magnet material is suppressed as much as possible in advance.

On the other hand, the temperature condition and time condition in the heat treatment step after preheating are set to 125 to 180 ° C. and 60 to 180 minutes, and the sheet-shaped magnet material is formed by stacking iron plates in upper and lower three stages, for example. It is left to stand for 60 to 180 minutes in a constant temperature bath consisting of a heating device or a steam can. When vulcanization is performed by this, a predetermined tensile strength is imparted. Also at this time, the entrainment of air in the sheet-shaped magnet material is suppressed in advance as much as possible. In the case of performing such high temperature heating, water and gas in the sheet-shaped magnet material have been diffused in advance by the above-described preheating step, so that the sheet-shaped magnet material may have problems such as air foaming during the heating step. It never happens.

During this heating, the heating temperature is 180 ° C.
If the temperature exceeds 125 ° C, the oxidation of the magnetic powder becomes remarkable and the magnetic properties deteriorate, and if the heating temperature is 125 ° C or lower, the vulcanization does not proceed and the required tensile strength cannot be obtained. For the same reason, heating time of 60 to 180 minutes is required.

The sheet-shaped magnet material which has been subjected to the heat treatment is cut into a suitable size to obtain a sheet-shaped magnet. After cutting, the sheet-shaped magnet material is cut at 100 to 180 ° C. and 20 to 18 ° C. in a constant temperature bath.
The heat treatment is performed again under the condition of 0 minutes. The re-heat treatment after cutting accelerates vulcanization not only from the original surface but also from the cut surface, so that the rigidity of the magnet is enhanced. In this reheat treatment step, the inside of the thermostatic chamber is made to be an inert atmosphere such as an N ₂ gas atmosphere, so that oxidation of the sheet-shaped magnet material is prevented. When the inside of the constant temperature bath is not made an inert atmosphere, a means such as wrapping the periphery with aluminum foil is provided so that the surface of the sheet-shaped magnet material is not exposed to the atmosphere as much as possible.

In the case of the rare earth-transition metal-boron (R-T-B) magnetic powder, the sheet-shaped magnet material after the above reheat treatment has a Shore hardness D of 45 ° or more and a tensile strength. It is made over 4.5Kg / mm ² . Also, the amount of bending is within 60 mm. Here, the amount of deflection is 2.55 mm x 2.45 mm in cross-sectional dimension and 205.5 mm in length dimension.
The base of 50 mm of the test piece molded in the size and shape of was fixed on a horizontal table, and the amount by which the free end of this test piece was bent by its own weight after 15 seconds was measured at an ambient temperature of 15 to 25 ° C. Define. If it is not within the range of heating temperature conditions as described above, it may cause deterioration of magnetic properties (when it exceeds the temperature range), or vulcanization does not proceed (when it falls below the temperature range), decrease of hardness, tensile strength. This causes a decrease in strength and an increase in the amount of bending.

The sheet magnet thus obtained is magnetized in a predetermined direction. At this time, when the rolled surface of the magnet using the rare earth-transition metal-boron (R-T-B) magnetic powder is magnetized, the surface magnetic flux density is set to 350 G to 1400 G. ,
When magnetizing a magnet using rare earth-transition metal-boron (R-T-B) magnetic powder on a surface orthogonal to the rolling surface, the surface magnetic flux density is in the range of 40G to 1400G.
Done The case where the rolling surface is magnetized is, for example, the case where the main surface is magnetized for driving a motor,
Further, the case where the magnetization is performed on the plane orthogonal to the rolling surface is, for example, the case where it is performed as the FG magnetization for motor rotation detection.

When the surface magnetic flux density exceeds 1400 G and is magnetized, the binder in the magnet overcomes the magnetic force and cannot fix the magnetic powder, and the magnet collapses. On the other hand, in the case where the rolled surface is subjected to main magnetization for driving a motor, for example, if the surface magnetic flux density is 350 G or less, the magnetic flux density is too small and the rare earth-transition metal-
The usefulness of using a boron (RTB) magnetic powder is lost. This is because it is sufficient for the magnet having a magnetic flux density of 350 G or less to use the ferrite-based magnetic powder, which has a low production cost. Further, when FG magnetization for motor rotation detection is performed on the plane orthogonal to the rolling surface, if the surface magnetic flux density is 40 G or less, the magnetic flux density is too small and the required F
The G waveform cannot be obtained.

[0038]

EXAMPLES Examples of the present invention will be described in detail below. Example 1 As the magnetic powder, M manufactured by General Motors was used.
N was crushed in advance by a wet ball mill to adjust the particle size.
d-Fe-B magnetic powder was used. Since this magnetic powder is a magnetic powder having a particle size of 2 mm or less when it is formed by the ultra-quenching method, it was pulverized to have a particle size of 78 μm or less. As a rust preventive agent, Kao's Leodol SP-O
10 was used, and Epicoat 828 manufactured by Yuka Shell Co., Ltd. was used as the epoxy main agent.

Then, in a ball mill container, magnetic powder,
Epoxy main agent, rust preventive agent and alumina balls were added, and the air in the container was replaced with N ₂ gas so that the oxygen concentration was 1.2%, and then mixed for 1 hour to oxidize the surface of the magnetic powder. A film, an epoxy resin film and an anticorrosive film were formed.

Next, the mixture thus obtained and the rubber binder were kneaded together with a curing agent and a curing accelerator in a pressure kneader for 7 minutes. As the above-mentioned hardening agent and hardening accelerator, YH-30 manufactured by Yuka Shell Co., Ltd.
2 and IBMI-12 were used.

Further, the obtained kneaded product was subdivided into small lots of 4 kg each, put in a vinyl bag, immediately tied at the mouth, and then stored in a closed container. Then, leave it for an appropriate time, take out the kneaded product from the closed container, and use a pulverizer to obtain a particle size of about 2.6 m.
It was crushed to about m. For the crusher, Urai 140 made by Horai Iron Works
A rotary blade type was used.

Rolling was performed while maintaining the surface temperature of the rolling roll used to obtain the sheet at about 50 ° C. to obtain a sheet-shaped magnet material. Then, after preheating the sheet magnet material under a temperature condition of about 50 ° C. for about 8 hours,
The rubber binder was vulcanized by heating to about 170 ° C.
Then, it was cut into a predetermined size to obtain a flexible sheet magnet.

The formulations in this example are shown in Table 1 below.

[Table 1] Nd-Fe-B magnetic powder in the above table is
It is set to 94.5% by weight. It was confirmed that according to such a compounding example, a sufficient magnetic force necessary for, for example, a motor can be obtained without causing the magnet to collapse due to the magnetic force.

In the kneading step of this example, it was confirmed that the activity of the surface of the magnetic powder was lowered by the rust-preventive coating formed in advance, and that air entrapment into the material hardly occurred. Further, the kneaded product is crushed into a predetermined small particle size under a flow of an inert gas by a crushing process,
From this, it was confirmed that air entrapment hardly occurs in the next rolling step.

In the rolling process, since the surface of the rolling roll was maintained at a predetermined temperature, the tensile strength of the sheet-like magnet was maintained well within the rollable range, and the oxidation of the magnetic powder was suppressed to suppress the magnetic force. There was no deterioration of the characteristics.

It was further confirmed that in the subsequent high-temperature heating, defects such as air bubbling did not occur in the sheet-shaped magnet material. If the heating temperature exceeds 180 ° C,
Oxidation of the magnetic powder became remarkable and the magnetic properties were deteriorated. When the heating temperature was 125 ° C. or lower, the vulcanization did not proceed and the predetermined tensile strength could not be obtained.

Further, in this example, since the epoxy resin was charged and mixed in the mixing step, and the epoxy resin film was formed on the magnetic powder there, air entrapment was further reduced. Similar effects and advantages were obtained by adding the epoxy resin in the kneading step.

The magnetic characteristics of the magnet obtained in this example are as follows: Br = 5.5 [KG], iHc = 9.9 [kOe], bHc = 4.5 [k]
Oe] and (BH) max = 6.2 [MGOe]. Further, when the obtained magnet was left in an atmosphere of 60 ° C. and 90% RH for 80 hours, no rust was observed on the surface. Further with brush D
When used as a driving magnet for a C motor, 60 ° C, 2
No corrosion occurred in the brush material (Ag-Pd) and the commutator material (Ag-Cd) even after continuous rotation for 00 hours.

[0051] As Example 2 ━━━━ magnetic _{powder, MM 14 (Fe 0. 9} Co 0. 1) 79 B 7
An alloy of the following composition was made into an ultra-quenched ribbon by the single roll method, and was crushed by a wet ball mill and the particle size was adjusted. As a rust preventive, Leodol SP-O10 manufactured by Kao
And a mixed solution of Anderol 456 manufactured by Tenneco Chemicals, Inc. of the United States were used. A sheet-like flexible magnet was obtained in the same manner as in Example 1 described above.

Also in the kneading step according to this example, it was confirmed that the activity of the surface of the magnetic powder was lowered by the rust-preventive coating formed in advance and that air was hardly entrained in the material. Further, this kneaded product was crushed into a predetermined small particle size under the flow of an inert gas in the crushing process, so that air entrapment hardly occurred in the subsequent rolling process.

Also in the rolling step, the surface temperature of the rolling roll was maintained at a predetermined value and a predetermined tensile strength was obtained. Further, the oxidation of the magnetic powder was similarly suppressed, and the magnetic characteristics were not deteriorated. Even in the next high-temperature heating, the sheet-shaped magnet material did not cause problems such as air foaming.

The magnetic characteristics of the magnet obtained in Example 2 were Br = 4.6 [KG], iHc = 7.0 [kOe], bHc = 3.0.
It was 1 [kOe] and (BH) max = 4.0 [MGOe]. Further, when the obtained magnet was left in an atmosphere of 60 ° C. and 90% RH for 80 hours, no rust was observed on the surface. Furthermore, when used as a driving magnet for a brushed DC motor, 60
Brush material (Ag-Pd) even after continuous rotation for 200 hours at ℃
No corrosion occurred on the commutator material (Ag-Cd).

As described above, it was confirmed that the sheet-shaped flexible bonded magnet according to the present invention is preferably attached to a rotating electric machine and used. As the magnetic powder, the same action and effect can be obtained by using ferrite magnetic powder in addition to rare earth-transition metal-boron magnetic powder. If a metal powder having a high magnetic permeability such as iron powder or an iron alloy is used instead of the permanent magnet powder, a flexible high magnetic permeability material can be formed.

[0056]

As described above, in the method for manufacturing a flexible bonded magnet according to the present invention, the sheet-shaped magnet material is preheated under predetermined conditions and is unavoidably contained in the sheet-shaped magnet material. Since the sheet-shaped magnet material is heat-treated after diffusing moisture and gas that are contained in the material to the outside,
It is possible to perform high temperature heating without causing problems such as air bubbling, and it is possible to satisfactorily commercialize a flexible bonded magnet while significantly improving the yield.

[Brief description of drawings]

FIG. 1 is a flow chart showing a manufacturing process of a flexible bonded magnet according to the present invention.

Claims (2)

[Claims] 1. A method for producing a flexible bonded magnet in which magnetic powder is dispersed in a binder resin having flexibility, the flexible bonded magnet comprising at least the following steps. Production method. (a) A step of kneading the magnetic powder and the binder resin. (b) A step of rolling the kneaded product obtained in the above step into a sheet. (c) A step of preheating a magnet material rolled into a sheet under predetermined conditions. (d) A step of applying heat treatment to the preheated sheet-shaped magnet material. (e) A step of cutting the sheet-shaped magnet material after the heat treatment. 2. The method for manufacturing a flexible bonded magnet according to claim 1, wherein the temperature condition and the time condition in the preheating step are set to 30 ° C. to 70 ° C. and 6 hours or more, respectively, and the temperature in the heat treatment step is set. A method for producing a flexible bonded magnet, characterized in that the conditions and time conditions are set to 125 ° C. to 180 ° C. and 60 minutes or more, respectively.