JP2021095616A - Bond magnet - Google Patents

Abstract

To provide a bond magnet excellent in not only magnetic characteristics but also mechanical physical properties.SOLUTION: A bond magnet includes magnetic powder treated with a coupling agent having an alicyclic structure, and a cured product of a thermosetting resin having an alicyclic structure.SELECTED DRAWING: None

Description

The present invention relates to a bonded magnet.

Patent Document 1 discloses a bonded magnet composed of a magnetic powder and a polymerizable monomer. Further, it is disclosed that the magnetic powder is surface-treated with a known surface treatment agent such as a coupling agent.

JP-A-2009-155545

An object of the present invention is to provide a bonded magnet having excellent mechanical properties as well as magnetic properties.

The bonded magnet according to one aspect of the present invention includes a magnetic powder treated with a coupling agent having an alicyclic structure and a cured product of a thermosetting resin having an alicyclic structure.

The bonded magnet according to one aspect of the present invention is excellent not only in magnetic properties but also in mechanical properties.

Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. In this specification, the term "process" is used not only for an independent process but also for the term "process" as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. included.

The bond magnet of the present embodiment includes a magnetic powder treated with a coupling agent having an alicyclic structure and a cured product of a thermosetting resin having an alicyclic structure. Since the thermosetting resin having an alicyclic structure has a lower viscosity than the conventional thermosetting resin having a polar group such as an epoxy resin or a phenol resin, the filling rate of the magnetic powder in the produced bond magnet is increased. be able to. Further, the coupling agent having an alicyclic structure can suppress an increase in viscosity when the coupling-treated magnetic powder and the resin are mixed, as compared with the conventional coupling agent having a polar group, and the obtained bond magnet can be suppressed. The filling rate of the magnetic powder inside can be increased. Further, the coupling agent having an alicyclic structure is likely to be directly bonded to a thermosetting resin having an alicyclic structure, and a cured product having a high crosslink density can be obtained. From these, it is considered that the mechanical properties are improved as well as the magnetic characteristics.

The material of the magnetic powder is not particularly limited, and examples thereof include SmFeN-based, NdFeB-based, and SmCo-based rare earth magnetic materials. Among them, SmFeN-based magnetic powder is preferable in terms of heat resistance and that it does not contain rare metals.

Examples of the SmFeN-based magnetic powder include a nitride composed of a rare earth metal Sm having _{a Th 2} Zn _17- type crystal structure and a general formula of Sm _x Fe _100-xy N _{y, iron Fe, and nitrogen N.} Be done. Here, it is preferable that x is 8.1 atomic% or more and 10 atomic% or less, y is 13.5 atomic% or more and 13.9 atomic% or less, and the balance is mainly Fe.

The SmFeN magnetic powder can be produced by the method disclosed in JP-A-11-189811. The NdFeB-based magnetic powder can be produced by the HDDR method disclosed in International Publication No. 2003/85147. The SmCo-based magnetic powder can be produced by the method disclosed in Japanese Patent Application Laid-Open No. 08-260883.

The average particle size of the magnetic powder is preferably 10 μm or less, more preferably 6 μm or less, and further preferably 4 μm or less from the viewpoint of magnetic properties. If it exceeds 10 μm, the coercive force of the magnetic powder tends to be significantly reduced due to the increase in crystal grain size. The average particle size is measured as a particle size corresponding to a cumulative volume of 50% from the small particle size side in the particle size distribution.

The magnetic powder can be treated with phosphoric acid. By the phosphoric acid treatment, a passivation film having a PO bond is formed on the surface of the magnetic powder.

The phosphoric acid treatment is carried out by reacting a phosphoric acid treatment agent with a magnetic powder. Examples of the phosphoric acid treatment agent include phosphates such as orthophosphoric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, zinc phosphate, calcium phosphate, and hypophosphite. Examples thereof include inorganic phosphoric acid such as phosphoric acid, hypophosphite type, pyrophosphate and polyphosphoric acid type, organic phosphoric acid and salts thereof.

The magnetic powder is preferably subjected to a silica treatment treated with an alkyl silicate from the viewpoint of protection from oxidation at the stage of producing the molded product and oxidation during use of the obtained molded product. The alkyl silicate is represented by the following general formula, and among them, methyl silicate or ethyl silicate is preferable.
Si _n O _(n-1) (OR) _{(2n + 2)}
(R is an alkyl group and n is an integer of 1-10.)

In the silica treatment, a silica film can be formed by mixing the above-mentioned alkyl silicate and the water required for hydrolyzing the silicate with the magnetic powder and heat-treating in an inert gas atmosphere. Examples of the water required for hydrolyzing the silicate include acidic aqueous solutions such as acetic acid aqueous solution, sulfuric acid and phosphoric acid aqueous solution, and basic aqueous solutions such as ammonia water, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution. The mixing amount of the alkyl silicate is preferably 1 part by weight or more and 4 parts by weight or less, and more preferably 1.5 parts by weight or more and 2.5 parts by weight or less with respect to 100 parts by weight of the magnetic powder.

The magnetic powder is treated with a coupling agent having an alicyclic structure. The treatment is preferably performed after the silica treatment has been performed. By treating with the coupling agent, the wettability with the thermosetting resin can be improved and the mechanical strength of the bond magnet can be improved.

The coupling agent having an alicyclic structure is not particularly limited as long as it has an alicyclic structure, but those having no polar group are preferable. Examples of the alicyclic structure include a monocyclo ring, a bicyclo ring, and a tricyclo ring, and a bicyclo ring is preferable. Examples of such a coupling agent include 2- (bicyclo [2.2.1] hepta-5-en-2-yl) ethyltrimethoxysilane as a silane coupling agent having a norbornene skeleton which is a bicyclo ring. -(Bicyclo [2.2.1] hepta-5-en-2-yl) ethyltriethoxysilane, 2- (bicyclo [2.2.1] hepta-5-en-2-yl) trimethoxysilane, 2- (Bicyclo [2.2.1] hepta-5-en-2-yl) triethoxysilane, 2- (bicyclo [2.2.1] hept-2-enyl) ethynyltrimethoxysilane, 2- (Vicyclo [2.2.1] hept-2-enyl) ethynyltriethoxysilane, 2- (bicyclo [2.2.1] hepta-5-en-2-yl) hexyltrimethoxysilane, 2-( Bicyclo [2.2.1] hepta-5-en-2-yl) hexyltriethoxysilane and the like can be mentioned. These coupling agents may be used alone or in combination of two or more. Among them, a coupling agent having a norbornene skeleton is more preferable in terms of compatibility with a thermosetting resin, slipperiness of the magnetic powder surface, heat resistance, etc., and 2- (bicyclo [2.2.1] hepta-5). -En-2-yl) ethyltrimethoxysilane and 2- (bicyclo [2.2.1] hepta-5-en-2-yl) ethyltriethoxysilane are more preferred.

The treatment with a coupling agent having an alicyclic structure is performed by mixing the above-mentioned coupling agent with the magnetic powder together with the water required for hydrolyzing the coupling agent and heat-treating in an inert gas atmosphere. A coating of the coupling agent can be formed. Examples of the water required for hydrolyzing the coupling agent include acidic aqueous solutions such as acetic acid aqueous solution, sulfuric acid and phosphoric acid aqueous solution, and basic aqueous solutions such as ammonia water, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution. The mixing amount of the coupling agent having an alicyclic structure is preferably 0.1 part by weight or more and 2 parts by weight or less, and more preferably 0.2 parts by weight or more and 1.2 parts by weight or less with respect to 100 parts by weight of the magnetic powder. .. If it is less than 0.1 parts by weight, the effect of the coupling agent is small, and if it exceeds 2 parts by weight, the magnetic properties tend to deteriorate due to the aggregation of the magnetic powder.

The magnetic powder treated with a coupling agent having an alicyclic structure further improves the lubricity, reduces the frictional force acting between the particles during compression molding, and highly fills the magnetic powder in the molded product. It is preferable to treat with a coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms. The alkyl group or alkenyl group preferably has 10 or more and 24 or less carbon atoms. Here, if the number of carbon atoms of the alkyl group or the alkenyl group is less than 8, the imparting of lubricity is insufficient, and if the number of carbon atoms is larger than 24, the viscosity of the treatment liquid increases remarkably, which tends to make uniform coating difficult. is there.

Examples of the coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms include a silane coupling agent, a phosphate coupling agent, and a hydrogen phosphite coupling agent. These coupling agents may be used alone or in combination of two or more. Here, the coupling agent has two or more different groups in the molecule, one having a group acting with an inorganic material and the other having a group acting with an organic material.

Examples of the silane coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms are those represented by the following general formula. Specific examples include decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and octyltriethoxysilane. Examples thereof include silane, and among them, octadecyltriethoxysilane and octyltriethoxysilane are preferable.
(R ¹ ) _x Si (OR ² ) _(4-x)
(R ¹ is an alkyl group represented by C _n H _{2n + 1 or an alkenyl group represented by C n} H _2n-1 , n is an integer of 8 to 24, and R ² is an alkyl represented by C _m H _{2 m + 1.} It is a group, m is an integer of 1 to 4, and x is an integer of 1 to 3.)
The group that acts on the organic material in the silane coupling agent refers to, for example, a group in which a silicon atom and a carbon atom are directly bonded to each other, which is R ¹ in the above formula, and the group that acts on the inorganic material is OR ² . ..

Examples of the phosphate coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms include those represented by the following general formula. Specific examples include didecyl acid phosphate, isodecyl acid phosphate, isotridigicyl acid phosphate, lauryl acid phosphate, oleyl acid phosphate, stearyl acid phosphate, isostearyl acid phosphate, tetracocil acid phosphate and the like. But oleyl acid phosphate is preferred.
(R ¹ O) _x PO (OH) _(3-x)
(R ¹ is an alkyl group represented by C _n H _{2n + 1 or an alkenyl group represented by C n} H _2n-1 , n is an integer of 8 to 24, and x is an integer of 1 to 2.)
Note that group which acts as the organic material in phosphate coupling agent, in the above formula is R ^{1 O,} groups which act as inorganic material is OH.

Examples of the hydrogen phosphite coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms include those represented by the following general formula. Specific examples include didecyl hydrogen phosphite, dilauryl hydrogen phosphite, diorail hydrogen phosphite, and the like, and among them, diorail hydrogen phosphite is preferable.
(R ¹ O) ₂ POH
(R ¹ is an alkyl group represented by C _n H _{2n + 1 or an alkenyl group represented by C n} H _2n-1 , and n is an integer of 10 to 24.)
The group that acts on the organic material in the hydrogen phosphite coupling agent is R ¹ O in the above formula, and the group that acts on the inorganic material is OH.

In the treatment with a coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms, the above-mentioned coupling agent is mixed with the magnetic powder together with the water required for hydrolyzing the coupling agent and is inert. A coating of the coupling agent can be formed by heat treatment in a gas atmosphere. Examples of the water required for hydrolyzing the coupling agent include acidic aqueous solutions such as acetic acid aqueous solution, sulfuric acid and phosphoric acid aqueous solution, and basic aqueous solutions such as ammonia water, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution. The mixing amount of the coupling agent is preferably 0.01 part by weight or more and 1 part by weight or less, and more preferably 0.05 part by weight or more and 0.5 part by weight or less with respect to 100 parts by weight of the magnetic powder. If it is less than 0.01 part by weight, sufficient lubricity cannot be imparted to the magnetic powder, and if it is 1 part by weight or more, the mechanical strength of the obtained molded product is impaired.

The thermosetting resin having an alicyclic structure is not particularly limited as long as it has an alicyclic structure, and examples thereof include a thermosetting monomer and a thermosetting prepolymer. Examples of the alicyclic structure include a monocyclo ring, a bicyclo ring, and a tricyclo ring. Examples of the thermosetting monomer include a norbornene-based monomer, an epoxy-based monomer, a phenol-based monomer, an acrylic-based monomer, and a vinyl ester-based monomer.

Norbornene-based monomers include tricyclo [5.2.1.0 ^2,6 ] deca-3,8-diene (dicyclopentadiene) and tricyclo [5.2.1.0 ^2,6 ] decane-3-ene. , Bicyclo [2.2.1] hepta-2,5-diene (2,5-norbornadiene), bicyclo [2.2.1] hepta-2-ene (2-norbornene), bicyclo [3.2.1] ] Octa-2-ene, 5-ethylidene-2-norbornene, bicyclo [2.2.1] hepto-5-ene-2,3-dicarboxylic acid anhydride, 5-vinylbicyclo [2.2.1] hepta -2-ene, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] Dodeca-4-en and the like can be mentioned. Thermocurable prepolymers include epoxy resin, phenol resin, melamine resin, guanamine resin, unsaturated polyester, vinyl ester resin, diallyl phthalate resin, silicone resin, alkyd resin, furan resin, acrylic resin, and urea having an alicyclic structure. Examples thereof include resins and allyl carbonate resins. Examples of the thermosetting polymer include a polyurethane resin having an alicyclic structure, a polyimide resin, and a polyester resin.

The viscosity of the thermosetting resin is not particularly limited, but is preferably 200 mPa · S or less, more preferably 100 mPa · S or less, further preferably 50 mPa · S or less, and most preferably 15 mPa · S or less. If it exceeds 200 mPa · S, the magnetic powder and the thermosetting resin are not sufficiently familiar with each other, and there is a tendency for molding failure.

A thermosetting resin initiator and a curing agent can be blended together with the thermosetting resin. Examples of the initiator include Grubbs catalysts, dihalogens, azo compounds and the like. Examples of the curing agent include amine-based curing agents, acid anhydride-based curing agents, polyamide-based curing agents, imidazole-based curing agents, phenol resin-based curing agents, polypeptide-based curing agents, polysulfide resin-based curing agents, and organic acid hydrazide-based curing agents. Examples thereof include a curing agent and an isocyanate-based curing agent. Examples of the amine-based curing agent include diaminodiphenyl sulfone, meta-phenylenediamine, diaminodiphenylmethane, diethylenetriamine, and triethylenetetramine.

The method for producing the bonded magnet of the present invention is not particularly limited, but a mixing method for curing the composition obtained by mixing the above-mentioned magnetic powder and the above-mentioned thermosetting resin, or the above-mentioned thermosetting Examples thereof include an impregnation method in which the above-mentioned magnetic powder is impregnated with the sex resin and then cured.

The mixing method preferably includes a step of mixing the magnetic powder and the thermosetting resin, a step of filling the mixture in a mold and compressing the mixture while magnetically aligning the mixture, and a heat treatment step of heat-treating the compression molded body. ..

In the impregnation method, the magnetic powder is compressed while being magnetically oriented to obtain a first molded product, and the first molded product is brought into contact with a thermosetting resin and then compressed to obtain a second molded product. It is preferable to include a second compression step and a heat treatment step of heat-treating the second molded product. When the first molded product obtained by compressing the magnetic powder while magnetically orienting and the thermosetting resin are brought into contact with each other and then compressed and heat-treated to cure the thermosetting resin, the filling rate and orientation of the magnetic powder are obtained. It is considered that the rate increases and the magnetic properties of the bonded magnet improve.

<First compression step>
In the first compression step, the magnetic powder is compressed while being magnetically oriented to obtain a first molded product. The first compression step may be performed not only once but also a plurality of times.

The magnitude of the external magnetic field applied for magnetic orientation is not particularly limited, but is preferably 0.5 T or more, and more preferably 1 T or more. Below 0.5T, the magnet tends to be unable to be sufficiently oriented.

In the first compression step, the structure of the mold used is not particularly limited, and for example, an external mold, an inner plate installed in the external mold, a punch for applying from the vertical direction, and an external mold are held. For example, a mold composed of a spring for the purpose. A mold having an inner plate is preferable so that excess thermosetting resin can be easily removed in the second compression step. The size of the mold is not particularly limited, but it is preferable that the volume of the molded product is 0.1 cm ³ or more and 10 cm ³ or less so that excess thermosetting resin can be easily removed.

The magnitude of the pressure applied to the mold is not particularly limited, but is preferably 0.1 ton / cm ² or more and less than 4 ton / cm ^{2, and} more preferably 0.5 ton / cm ² or more and less than 2 ton / cm ^2. If it is less than 0.1 ton / cm ² , the rearrangement of the magnetic powder does not proceed and the filling rate of the magnetic powder in the second molded product tends to decrease. At 4 ton / cm ² or more, the first molded product is impregnated with resin. When it is made to be impregnated sufficiently, it tends to be poorly molded.

<Second compression step>
In the second compression step, the first molded product and the thermosetting resin are brought into contact with each other and then compressed to obtain a second molded product. When the average particle size of the magnetic powder used is as small as 10 μm or less, it is bulky and the filling rate is low. In the first compression step, when the magnet is sufficiently magnetically oriented and then brought into contact with a thermosetting resin and compressed, excess thermosetting resin is removed, the filling rate and orientation rate of the magnetic powder increase, and the bond magnet is used. The magnetic properties of the are improved.

The method of bringing the thermosetting resin into contact with the first molded product is not particularly limited, and the first molded product existing in the mold may be impregnated with, for example, a thermosetting resin. The amount of the thermosetting resin to be brought into contact is not particularly limited, but is preferably 0.25 times or more and 2 times or less, and more preferably 0.5 times or more and 1.5 times or less the volume of the molded product. If it is less than 0.25 times, the first molded product cannot be sufficiently impregnated with the thermosetting resin, resulting in molding failure. If it exceeds 2 times, the resin and magnetic powder overflow from the mold and the yield decreases. At the same time, the overflowing material tends to have to be removed.

The magnitude of the pressure applied in the second compression step is not particularly limited, but it is preferably equal to or higher than the compression pressure in the first compression step in terms of producing a magnet having a higher filling. Specifically, 4 tons / cm ² or more and 11 tons / cm ² or less is preferable, and 6 tons / cm ² or more and 10 tons / cm ² or less is more preferable. If it is less than 4 tons / cm ² , the filling rate of the magnetic powder cannot be sufficiently increased, and if it ^{exceeds 11 tons / cm 2} , the coercive force tends to decrease.

In the second compression step, magnetic orientation can be performed in the same manner as in the first compression step. In the case of magnetic orientation, the magnitude of the applied external magnetic field is not particularly limited, and the magnitude of the external magnetic field in the first compression step can be applied as it is.

<Heat treatment process>
The heat treatment temperature is not particularly limited, but is preferably 100 ° C. or higher and 150 ° C. or lower, and more preferably 110 ° C. or higher and 130 ° C. or lower. If the temperature is lower than 100 ° C., the curing of the resin does not proceed sufficiently and the strength becomes insufficient.

The heat treatment time is not particularly limited, but is preferably 1 minute or more and 120 minutes or less, and more preferably 3 minutes or more and 60 minutes or less. If it is less than 1 minute, the curing of the resin does not proceed sufficiently and the strength becomes insufficient, and if it exceeds 120 minutes, the resin tends to be oxidized by air and the strength tends to be insufficient.

After the heat treatment is completed, the inner plate and the punch are pulled out from the mold, the bonded magnet molded body is taken out, and magnetization can be performed by applying a pulse magnetic field in the orientation direction.

The magnetizing magnetic field is preferably 1T or more and 36T or less, and more preferably 3T or more and 12T or less. If it is less than 1T, the magnet cannot be sufficiently magnetized and the residual magnetic flux density cannot be obtained. If it exceeds 36T, the heat shock due to the heat generated at the time of magnetization is too large, and the magnet breaks.

The ratio of the magnetic powder contained in the bond magnet, that is, the filling rate is not particularly limited, but is preferably 71% by volume or more, and more preferably 72% by volume or more. If it is less than 71% by volume, it tends to be impossible to obtain a sufficient residual magnetic flux density.

The coercive force of the bond magnet is not particularly limited, but is preferably 1020 kA / m or more, and more preferably 1150 kA / m or more. Below 1020 kA / m, demagnetization tends to occur when used in a powerful motor or the like.

The residual magnetic flux density of the bond magnet is not particularly limited, but is preferably 0.75 T or more, and more preferably 0.8 T or more. If it is less than 0.75T, it tends to be impossible to draw out sufficient torque when it is used for a motor or the like.

The orientation rate of the magnetic flux of the bond magnet is preferably 80% or more, more preferably 81% or more. When it is 80 or more, the residual magnetic flux density becomes high. Here, the orientation rate is obtained by dividing the residual magnetic flux density of the bond magnet by the product of the residual magnetic flux density of the magnetic powder and the volume filling rate of the bond magnet.

The bending strength of the bond magnet is preferably 30 MPa or more, more preferably 60 MPa or more. Here, the bending strength is a value measured according to JIS K7171 using a test piece of 80 mm × 10 mm × 3 mm.

Hereinafter, examples will be described. Unless otherwise specified, "%" is based on weight.

Manufacturing example 1
[Alkyl silicate treatment process]
300 g of SmFeN magnetic powder (average particle size 3 μm) and _{7.5 g of ethyl silicate (Si 5} O ₄ (OEt) ₁₂ ) were added to the mixer and mixed for 5 minutes in a nitrogen atmosphere. Subsequently, 0.8 g of ammonia water having a pH of 11.7 was added, mixed for 5 minutes, and heat-treated at 180 ° C. under reduced pressure for 10 hours to obtain an SmFeN-based anisotropic magnetic powder having a silica thin film formed on the surface. ..

[Surface treatment step 1]
300 g of silica-treated magnetic powder and 1.5 g of an aqueous acetic acid solution having a pH of 4 were added to the mixer, and the mixture was mixed in a nitrogen atmosphere for 5 minutes. Subsequently, as the coupling agent A, 2- (bicyclo [2.2.1] hepta-5-en-2-yl) ethyltrimethoxysilane (silane coupling agent X-88-351 manufactured by Shin-Etsu Chemical Co., Ltd.) 3 g was added and mixed for 5 minutes in a nitrogen atmosphere. The mixture was taken out and heat-treated at 100 ° C. for 5 hours under reduced pressure to obtain a SmFeN-based anisotropic magnetic powder having a coating layer formed of the coupling agent A on a silica film (magnetic powder 1).

Manufacturing example 2

[Surface treatment step 2]
300 g of SmFeN magnetic powder having a coating layer formed from the coupling agent A obtained in Production Example 1 and 1.5 g of an aqueous acetic acid solution having a pH of 4 were added to the mixer and mixed for 5 minutes in a nitrogen atmosphere. Subsequently, a mixed solution of 0.5 g of octadecyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.5 g of ethanol was added as the coupling agent B, and the mixture was mixed in a nitrogen atmosphere for 5 minutes. Heat treatment was performed at 100 ° C. under reduced pressure for 5 hours to obtain an SmFeN-based anisotropic magnetic powder (magnetic powder 2) having a coating layer formed of the coupling agent A and the coupling agent B on the surface.

Manufacturing example 3
Coupling with coupling agent A on the surface in the same manner as in Production Example 2 except that octyltriethoxysilane was used as the coupling agent B in the surface treatment step 2 of Production Example 2. An SmFeN-based anisotropic magnetic powder (magnetic powder 3) having a coating layer formed from the agent B was obtained.

Manufacturing example 4
In the surface treatment step 2 of Production Example 2, the coupling agent A and the coupling agent were used on the surface in the same manner as in Production Example 2 except that oleyl acid phosphate was used as the coupling agent B instead of octadecyltriethoxysilane. An SmFeN-based anisotropic magnetic powder (magnetic powder 4) having a coating layer formed from B was obtained.

Production example 5
In the surface treatment step 2 of Production Example 2, the coupling agent A and the cup were formed on the surface in the same manner as in Production Example 2 except that diorail hydrogen phosphite was used as the coupling agent B instead of octadecyltriethoxysilane. An SmFeN-based anisotropic magnetic powder (magnetic powder 5) having a coating layer formed from the ring agent B was obtained.

Production example 6
In the surface treatment step 1 of Production Example 2, vinyltrimethoxysilane is used as the coupling agent A instead of 2- (bicyclo [2.2.1] hepta-5-en-2-yl) ethyltrimethoxysilane. An SmFeN-based anisotropic magnetic powder (magnetic powder 6) having a coating layer formed of the coupling agent A and the coupling agent B on the surface was obtained in the same manner as in Production Example 2.

Production example 7
In the surface treatment step 1 of Production Example 2, vinyltrimethoxysilane is used as the coupling agent A instead of 2- (bicyclo [2.2.1] hepta-5-en-2-yl) ethyltrimethoxysilane. Then, in the surface treatment step 2, a coating layer formed of the coupling agent A and the coupling agent B was formed on the surface in the same manner as in Production Example 2 except that octyltriethoxysilane was used instead of the octadecyltriethoxysilane. An SmFeN-based anisotropic magnetic powder (magnetic powder 7) having the above was obtained.

Example 1
First compression step SmFeN-based anisotropic magnetic powder having a coating layer formed of a coupling agent A on its surface, which was produced in Production Example 1 in a non-magnetic cemented carbide mold provided with a 5 mm square cavity. 0.8 g of magnetic powder 1) was filled, upper and lower punches were attached, and compression was performed at a compression pressure of 1 ton / cm ^{2 in} a 1 T orientation magnetic field to obtain a first molded product.

Second compression step Subsequently, the upper punch is removed, and dicyclopentadiene monomer (viscosity 3 mPa · s, density 1.02 g / cc) and dichloro [1,3-bis (2,3) as a reaction initiator are added to the first molded product. A mixed solution of 6-isopropylphenyl) -2-imidazolidinilidene] (2-isopropylphenylmethylene) ruthenium (III) was added dropwise in an amount of 0.1 g and held for 30 seconds. The upper punch was attached again, and the mixture was compressed at a compression pressure of 8 ton / cm ^{2 in} a 1T orientation magnetic field to impregnate the dicyclopentadiene monomer and discharge excess mixed solution components to obtain a second molded product. ..

Heat treatment step The second molded product was subsequently heated at 120 ° C. for 15 minutes in a compressed state to obtain a bonded magnet. The density, volume filling rate, coercive force, residual magnetic flux density, orientation rate, and bending strength of the obtained bond magnet were measured by the methods shown below. The results are shown in Table 1.

<Density and volume filling rate>
The density of the bonded magnet was calculated by measuring the dimensions and weight. The volume filling factor was calculated by applying the density calculated from the calibration curve of the magnetic powder filling factor and the magnet density prepared based on the densities of the magnetic powder and the resin.

<Residual magnetic flux density, coercive force and orientation rate>
The SmFeN magnetic powder is packed in a sample container together with the paraffin wax, the paraffin wax is melted by a dryer, and then the magnetic domains that are easily magnetized are aligned by a 2T orientation magnetic field. This magnetic field oriented sample is pulse-magnetized with a magnetizing magnetic field of 6T, and the residual magnetic flux density (T) and coercive force iHc (kA / m) are measured using a VSM (vibration sample type magnetic field meter) with a maximum magnetic field of 2T. As a result, the residual magnetic field density of the SmFeN magnetic powder was 1.317T, and the coercive force was 1300 kA / m. Further, when the residual magnetic flux density (T) and the coercive force iHc (kA / m) of the manufactured bond magnet were measured using a BH tracer, the residual magnetic flux density of the magnet was 0.70 T and the coercive force was 1080 kA / m. there were. Therefore, the orientation ratio was 0.75 (T) / (0.703 × 1.317 (T)) × 100 = 76.0%.

<Bending strength>
The measurement was performed using a test piece of 80 mm × 10 mm × 3 mm according to JIS K7171.

Examples 2-6
Table 1 shows the use of the SmFeN-based anisotropic magnetic powder (magnetic powder 2) having a coating layer formed of the coupling agent A and the coupling agent B on the surface and the compression pressure in the first compression step. The same procedure as in Example 1 was carried out except that the conditions were changed to the above conditions, and a bonded magnet was produced.

Example 7
0.8 g of magnetic powder (magnetic powder 2) of SmFeN produced in Production Example 2, 0.05 g of dicyclopentadiene monomer (viscosity / 25 ° C.: 3 mPa · s, density: 1.02 g / cc) as a binder component, and a reaction initiator. As a mixture, 0.002 g of dichloro [1,3-bis (2,6-isopropylphenyl) -2-imidazolidinilidene] (2-isopropylphenylmethylene) ruthenium (III) was mixed in a dairy pot. This mixture is filled in a non-magnetic cemented carbide mold provided with a 5 mm square cavity, and then compressed by applying a compression pressure ^{of 8 ton / cm 2 in the vertical direction of the mold while applying a 1T alignment magnetic field.} At the same time, the excess binder component was discharged, and the bonded magnet was obtained by heating at 120 ° C. for 15 minutes in that state. Table 1 shows the results of the obtained bond magnet density, volume filling rate, coercive force, residual magnetic flux density, orientation rate, and bending strength.

Examples 8-10 and Comparative Examples 1-2
A bonded magnet was produced in the same manner as in Example 1 except that the magnetic powder was changed to that shown in Table 1.

From Table 1, as shown in Examples 1 to 10, the bonded magnet containing the magnetic powder treated with the coupling agent having an alicyclic structure and the cured product of the thermosetting resin having an alicyclic structure has magnetic characteristics. The bending strength became a very high value while maintaining the above. On the other hand, as shown in Comparative Examples 1 and 2, the bonded magnet containing the magnetic powder not treated with the coupling agent having an alicyclic structure and the cured product of the thermosetting resin having an alicyclic structure has a bending strength. It was very low. Further, the bonded magnet containing the coupling agent having an alicyclic structure of Examples 2 to 10 and the magnetic powder treated with the coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms is described in Example 1. The residual magnetic flux density is higher than that of a bonded magnet containing a magnetic powder treated with a coupling agent having an alicyclic structure and not treated with a coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms. It got higher.

Since the bonded magnet of the present invention is excellent in mechanical properties as well as magnetic characteristics, it can be suitably applied to applications such as motors.

Claims (10)

A bond magnet containing a magnetic powder treated with a coupling agent having an alicyclic structure and a cured product of a thermosetting resin having an alicyclic structure. The bond magnet according to claim 1, wherein the thermosetting resin is a thermosetting monomer or a thermosetting prepolymer. The bond magnet according to claim 2, wherein the thermosetting monomer is a norbornene-based monomer. The bond magnet according to claim 3, wherein the norbornene-based monomer is dicyclopentadiene. The bond magnet according to claim 1, wherein the alicyclic structure in the coupling agent having an alicyclic structure has a norbornene skeleton. The bond magnet according to claim 5, wherein the norbornene skeleton is a bicyclo ring. The bond magnet according to any one of claims 1 to 6, wherein the magnetic powder is a magnetic powder further treated with a coupling agent having an alkyl group or an alkenyl group having 8 or more and 24 or less carbon atoms. The bond magnet according to any one of claims 1 to 7, wherein the proportion of the magnetic powder is 71% by volume or more. The bond magnet according to any one of claims 1 to 8, wherein the magnetic powder is an SmFeN-based magnetic powder. The bond magnet according to any one of claims 1 to 9, wherein the bending strength is 30 MPa or more.