JPH06333712A - Composition for resin bonded type magnet and resin-bonded type magnet - Google Patents

Abstract

PURPOSE:To realize a resin-bonded type magnet having excellent mechanical strength as magnetic characteristics by using magnetic powder having a specific anisotropic magnetic field and containing an epoxy resin having a polysulfide skeleton in a main chain and a novolak type epoxy resin in a resin binder. CONSTITUTION:Na-Fe-three group magnetic powder having an anisotropic magnetic field of 50kOe or more is used as magnetic powder. The epoxy-resin chief agents of a resin binder have two kinds of epoxy resins of an epoxy resin having a polysulfide skeleton in at least a main chain and a novolak type epoxy resin as components. An aromatic amine epoxy resin curing agent is employed as the epoxy resin curing agent of the resin binder. These compositions are press-molded by various compression molding equipments, the binder resins are cured through heat treatment, and the whole is magnetized in the magnetic field, thus acquiring a resin-bonded magnet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition which gives a resin-bonded magnet excellent in magnetic properties and radial crushing strength, and a resin-bonded magnet using the composition.

[0002]

2. Description of the Related Art Due to their excellent magnetic properties, rare earth permanent magnets are being applied in a wide range of fields including general home appliances, communication / audio equipment, medical equipment, and general industrial equipment. This rare earth permanent magnet is classified into a resin-bonded type and a sintered type. Resin-bonded magnets are magnetic powders mixed with a resin binder and press-molded, so compared to sintered magnets,
(1) It has high dimensional accuracy and can be molded into complicated shapes. (2)
There are advantages such as high uniformity of quality and performance, (3) good yield and good machinability. However, if the compounding ratio of the resin binder is increased, the mechanical strength increases and cracks and chips do not occur during assembly, but as the ratio increases, the ratio of the magnetic powder decreases and the magnetic properties of the magnet deteriorate. .

On the other hand, resin-bonded magnets used in small motors, audio equipment, office automation equipment, etc., have excellent mechanical strength, especially ring radial crushing strength, and high magnetic characteristics because of the demand for downsizing of the equipment. Is required. A resin-bonded magnet using an epoxy resin as a binder has been proposed as a material satisfying the contradictory requirements of improving the magnetic properties and the mechanical strength. When an epoxy resin is used as a binder, high magnetic properties can be obtained without significantly impairing ring radial crushing strength, heat resistance, and moldability.

[0004]

However, there is a limit to the improvement of mechanical strength when only a single epoxy resin is used, and thin molded articles and the like still have insufficient mechanical strength.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a resin-bonded magnet composition having excellent magnetic properties and mechanical strength of the obtained magnet even if the ratio of the binder resin is suppressed to a low level, And to provide a resin-bonded magnet obtained by the composition.

[0005]

In order to achieve the above object, the inventors of the present invention have conducted various studies on resins used as binders of resin-bonded magnets, and as a result, have the following resin-bonded type It was found that a composition for magnets was obtained, and the present invention was completed. That is, the resin-bonded magnet composition of the present invention is a resin-bonded magnet composition comprising magnetic powder and a resin binder, wherein the magnetic powder has an anisotropic magnetic field of 50 kOe or more, and the resin binder is mainly It is characterized in that it contains an epoxy resin having a polysulfide skeleton in its chain, a novolac type epoxy resin, and, if necessary, an aromatic amine epoxy resin curing agent. Further, the resin-bonded magnet of the present invention is characterized in that it is obtained by pressure-molding the composition for a resin-bonded magnet described above, followed by heat curing.

As the magnetic powder used in the present invention, any magnetic powder having an anisotropic magnetic field (H _A ) of 50 kOe or more can be used without particular limitation. Therefore, as long as this condition is satisfied, magnetic powders that are usually used in resin-bonded magnets can be used. For example, rare-earth cobalt-based materials such as Sm-Co ₅ series and Sm ₂ (CoFeZrV) ₁₇ series, Nd-Fe-Co- B system, Nd-Dy
-Fe-B type, Nd-Fe-B type rare earth-iron-boron type,
Sm-Fe-N system, Nd-Fe-Ti-N system, Nd-Fe-V-
N-based nitride-based magnetic powder and the like can be mentioned. In any case, the particle size of the magnetic powder is usually 35 mesh (JI
S) or less is preferable.

In the case of the rare earth-iron-boron system exemplified above as the magnetic powder, it is particularly preferable to use the alloy powder by the liquid quenching method. Liquid quenching method, the alloy of the required composition is melted by a method such as high frequency induction heating, and the resulting molten metal is sprayed onto a high-speed rotating copper or aluminum roll to be rapidly cooled to form a ribbon having a thickness of several tens of microns. By subjecting this ribbon to an appropriate heat treatment, for example, the average crystal grain size is increased to 3000.
It is a method of obtaining a magnetic powder by dry- or wet-milling with a stamp mill, a ball mill or the like after adjusting to A or less.

The epoxy resin main component of the resin binder contains at least two kinds of epoxy resins, an epoxy resin having a polysulfide skeleton in the main chain and a novolac type epoxy resin. If the first component of the epoxy resin is an epoxy resin having a polysulfide skeleton in the main chain, it can be used without any restriction on the molecular weight, the molecular weight distribution, the side chain, the functional group and the like. The second component of the epoxy resin may be a cresol novolac type or a phenol novolac type as long as it is a novolac type epoxy resin, and it can be used without any particular restrictions on the molecular weight, the molecular weight distribution, the side chain, the functional group and the like.

In addition to these epoxy resins, as the third component or more, for example, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, linear aliphatic epoxide type epoxy resin, aliphatic The epoxide type epoxy resin or the like may be used alone or in a combination of two or more, and additionally mixed and used.

The amount of the novolac type epoxy resin is 5 parts by weight or more and 950 parts by weight or less, preferably 10 parts by weight or more based on 100 parts by weight of the epoxy resin having a polysulfide skeleton in the main chain. 90
It is 0 parts by weight or less. When the amount of the novolac type epoxy resin is less than 5 parts by weight or more than 950 parts by weight, it is difficult to obtain sufficient ring radial crushing strength. The content of the binder resin in the composition of the present invention is preferably 0.5 to 5 parts by weight, and more preferably 1.0 to 3.0 parts by weight, based on 100 parts by weight of the magnetic powder.

An aromatic amine epoxy resin curing agent can be used as the epoxy resin curing agent of the resin binder. As the epoxy resin curing agent, if it is an aromatic amine type, it can be used without particular restrictions on molecular weight, molecular weight distribution, side chains, functional groups and the like. The content of the epoxy resin curing agent in the resin binder is preferably 1 to 40 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the total amount of the epoxy resin main agent. The epoxy resin or the epoxy resin curing agent can be used as it is or in a state of being dissolved in an organic solvent such as acetone or methyl ethyl ketone.

Examples of the aromatic amine curing agent include, for example,
m-phenylenediamine, p, p'-diaminodiphenylmethane, p, p'-diaminodiphenylsulfone,
Metaxylenediamine, xylenediamine, 1,3-
Any curing agent generally called aromatic polyamine or aromatic amine such as bis (aminomethyl) cyclohexane can be used, and of course, modified products thereof can also be used. It is difficult to specify an appropriate amount of the above-mentioned aromatic amine-based curing agent because the epoxy equivalent and active hydrogen equivalent differ depending on the type of epoxy resin and the type of aromatic amine-based curing agent that are configured, In particular, it is preferable to use 0.01 to 10 parts by weight, particularly 0.1 to 5 parts by weight, per 100 parts by weight of the magnetic powder. Even if used more than 5 parts by weight, 0.1
Even if used in a smaller amount, the mechanical strength of the resin-bonded magnet is impaired.

Other resin curing agents and curing accelerators may also be used. For example, as the resin curing agent, a single polyamine type curing agent, a modified polyamine type curing agent, an acid anhydride type curing agent, a polyphenol type curing agent, a polymercaptan type curing agent, an anionic polymerization curing agent, a cationic polymerization type curing agent, etc. Can be mentioned. Examples of the curing accelerator include tertiary amines, imidazoles, organic metal salts, chlorides, organic peroxides and the like. These resin curing agents and curing accelerators may be used in combination of two or more, if necessary.

Furthermore, in addition to the above magnetic powder and resin binder, known Si-based, Ti-based or Al-based chemically-bonded surface-treating agents, curing catalysts, etc. may be added alone or in combination. can do. Si-based, T
Examples of the i-type and Al-type chemically-bonded surface treatment agents (coupling agents) include vinyltriethoxysilane and γ.
-Aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N-
(Β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane, γ
-Methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, isopropyltriisostearoyl titanate, isopropyltris (dioctylpyrophosphate) titanate, isopropyltri (N-aminoethyl-aminoethyl) titanate, tetraoctylbis (ditrityl) Typical examples are decyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate, and acetoalkoxyaluminum diisopropylate. These can be mixed into the composition by, for example, a dry method, a wet method, an integral blend method, or the like,
Improves the adhesion between the magnet powder and the resin binder.

The resin-bonded magnet composition can be obtained by mixing the required components, but the mixing method is not particularly limited. For example, the organic component is dissolved in an organic solvent such as methyl ethyl ketone and mixed with the magnetic powder. After that, a wet method for obtaining a composition by drying, for example, a dry method of collectively mixing required components in a mixer such as a ribbon blender, a tumbler, a Nauter mixer, a Henschel mixer, a super mixer, or a high speed mixer may be used. . The composition thus obtained is in powder form.

The resin-bonded magnet using the above composition is obtained by press-molding the above-mentioned composition by various compression molding devices, heat-treating it to cure the binder resin, and then magnetizing it in a magnetic field. can get. Press molding of the composition is usually performed under a pressure of 4 to 8 t / cm ² , and curing of the binder resin is 0.5 to 4 at a temperature of 150 to 200 ° C. when an aromatic amine-based epoxy resin curing agent is used.
If not used for about an hour, at room temperature to 200 ° C.
The reaction may be performed for about 5 to 24 hours.

[0017]

In the composition of the present invention, as the binder resin,
Since a mixture of an epoxy resin having a polysulfide skeleton in the main chain and a novolac resin is used, a higher polymerization rate is obtained when cured than when each of these resins is used alone, and the magnetic powder It is considered that the excellent mechanical strength can be obtained because the adhesive strength of the resin layer is significantly increased.

[0018]

EXAMPLE A resin-bonded magnet composition and a magnet were manufactured and evaluated by the following materials and methods. The materials used are shown below.

A Magnetic powder-Magnetic powder 1: Nd-Fe-B magnet powder (trade name: MQP-B, manufactured by General Motors of the United States) Anisotropic magnetic field: 70.4 kOe-Magnetic powder 2: Sm-Co ₅ Magnetic powder (trade name: RCo ₅ alloy, manufactured by Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 246 kOe, average particle size 10 μm

B Epoxy resin I Epoxy resin: Epoxy resin having a polysulfide skeleton in the main chain (trade name: Flep 60, manufactured by Toray Thiokol Co., Ltd.) Epoxy resin II: cresol novolac type epoxy resin (trade name: EOCN- 1025, manufactured by Nippon Kayaku Co., Ltd.

C Curing agent-Curing agent i: Aromatic amine-based epoxy resin curing agent (trade name: HT972, manufactured by Ciba-Geigy Co., Ltd.)-Curing agent ii: Dicyandiamide

The compositions of Examples and Comparative Examples are shown in Tables 1-5. The composition was adjusted by blending the amounts of the resin and the curing agent shown in Tables 1 to 5 and diluting 10 times with methyl ethyl ketone.
It was added to 100 parts by weight of magnetic powder. In Examples 1 to 5 and Comparative Examples 1 to 3 shown in Table 1 and Table 2, dicyandiamide was used as a curing agent in an amount of 10% by weight based on the total amount of resin.
Using. After stirring the mixture of the magnetic powder and the solution obtained by diluting the resin and the like, methyl ethyl ketone was completely volatilized under reduced pressure of 30 ° C. and 10 ⁻¹ Torr to obtain each composition.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

Next, the obtained compositions of Examples and Comparative Examples were fed into a press die, and the molding surface pressure was 5.7 t / cm ^2.
It was press molded with. Example 5, Comparative Example 3, Example 10,
Also, the molding was performed in the magnetic field only when the Sm-Co ₅ magnetic powder of Comparative Example 6 was used. The obtained molded product has a length of 10 m.
It had a rectangular parallelepiped shape with m, width 15 mm, and thickness 5 mm. This molded sample was heat-treated for 1 hour to cure the binder resin in the sample and obtain a resin-bonded magnet sample. The heat treatment temperature is 185 ° C. in Examples 1 to 5 and Comparative Examples 1 to 3, and Examples 6 to 13 and Comparative Examples 4 to
In Comparative Example 6, the temperature was 145 ° C. Next, the magnetic characteristics of these samples were measured at room temperature with a Thiophie type self-recording magnetometer.
(BH) _max (maximum magnetic energy product) of magnetic characteristics
The results are shown in Tables 1 to 5.

Next, the same composition as described above was fed into a ring mold and press-molded at a molding surface pressure of 5 t / cm ² to give an outer diameter of 3
A cylindrical molded body having a diameter of 4 mm, an inner diameter of 32 mm and a height of 8 mm was obtained. Each of these molded bodies was heat-treated at atmospheric pressure for 1 hour to cure the binder resin in the sample and obtain a sample for ring radial crushing strength measurement. The heat treatment temperature is 185 ° C. in Examples 1 to 5 and Comparative Examples 1 to 3, and 145 in Examples 6 to 13 and Comparative Examples 4 to 6.
℃ was made. The ring radial crushing strength of the sample is Shimadzu Corporation.
Using an Autograph manufactured by K.K., the head speed was set to 1 mm / min and the temperature was determined at room temperature. The results are shown in Tables 1 to 5.

It is sufficient for the (BH) _max (maximum magnetic energy product) of the magnet to be 8 MGOe or more. Further, if the ring radial crushing strength is 3 gf or more, the mechanical strength is sufficient. As shown above, it can be seen that the resin-bonded magnet of the present invention has excellent magnetic properties and mechanical strength.

[0031]

Industrial Applicability The resin-bonded magnet composition of the present invention is excellent in both magnetic properties and mechanical strength of the obtained magnet, and is therefore suitable for general household appliances, communication / audio equipment, medical equipment, and general industrial equipment. It is expected that performance will be improved and its range of use will be expanded in a wide range of fields.

Claims (4)

[Claims] 1. A resin-bonded magnet composition comprising magnetic powder and a resin binder, wherein the magnetic powder has an anisotropic magnetic field of 50 kOe or more, and the resin binder is an epoxy resin having a polysulfide skeleton in the main chain. A resin-bonded magnet composition comprising a novolac type epoxy resin. 2. A resin-bonded magnet composition comprising a magnetic powder and a resin binder, wherein the magnetic powder has an anisotropic magnetic field of 50 kOe or more, and the resin binder is an epoxy resin having a polysulfide skeleton in its main chain. A resin-bonded magnet composition comprising a novolac type epoxy resin and an aromatic amine type epoxy resin curing agent. 3. A resin-bonded magnet composition containing a magnetic powder having an anisotropic magnetic field of 50 kOe or more, an epoxy resin having a polysulfide skeleton in the main chain, and a novolac type epoxy resin, after pressure molding, Resin-bonded magnet obtained by heating and curing. 4. A resin-bonded magnet containing magnetic powder having an anisotropic magnetic field of 50 kOe or more, an epoxy resin having a polysulfide skeleton in its main chain, a novolac type epoxy resin, and an aromatic amine type epoxy resin curing agent. A resin-bonded magnet obtained by press-molding a composition for pressurization and then heat-curing the composition.