JPH0982513A - Resin bonded magnet and composition therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the magnetic characteristic and mechanical strength of a magnet, by making the anisotropic magnetic strength of its magnetic powder not smaller than a specific value, and by making its resin binder contains as the effective components thereof specific resins and specific hardening agents. SOLUTION: A resin bonded magnet composite comprising a magnetic powder and a resin binder, wherein the anisotropic magnetic field strength of the magnetic powder is not smaller than 50kOe and the resin binder contains as its effective components a bisphenol type epoxy resin, a novolak type epoxy resin, an aromatic amine based epoxy resin hardening agent and a third amine salt epoxy resin hardening agent. A resin bond type magnet obtained by molding pressingly this resin bonded magnet composite and by hardening thereafter in a heating way the same. Thereby, the magnet with an excellent magnetic characteristic and mechanical strength is obtained to make performance improvements possible in such wide fields as domestic electric products and communicating, acoustic and medical apparatuses, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 Rare earth permanent magnets are being applied in a wide range of fields from their excellent magnetic properties to 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.
(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. However, in order to obtain high magnetic properties, curing at low temperature is inevitable, but using a curing reaction catalyst such as a low temperature curing type curing agent or an imidazole compound deteriorates the storage property (pot life), which is a contradictory feature. have.

[0004]

In order to improve the storage characteristics (pot life) of the composition, it is necessary to use a curing agent that reacts at a high temperature, and therefore the magnetic characteristics associated with oxidative deterioration of the molded magnet and the like. The decline was a problem.

The present invention has been made in view of the above circumstances, and an object thereof is to preserve the composition (pot life), magnetic properties and mechanical strength of the obtained composition even if the curing temperature of the binder resin is kept low. The present invention provides a resin-bonded magnet composition having excellent properties, and a resin-bonded magnet obtained by the composition.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted various studies on a curing agent for an epoxy resin used as a binder of a resin-bonded magnet, and as a result, have the following objects. The present invention was completed by discovering that a resin-bonded magnet composition as described below was obtained.

That is, the resin-bonded magnet composition of the present invention comprises
In a resin-bonded magnet composition comprising a magnetic powder and a resin binder, the magnetic powder has an anisotropic magnetic field of 50 kOe.
The above is characterized in that the resin binder contains a bisphenol type epoxy resin, a novolac type epoxy resin, an aromatic amine epoxy resin curing agent, and a tertiary amine salt epoxy resin curing agent as active ingredients. .

The resin-bonded magnet of the present invention comprises a magnetic powder having an anisotropic magnetic field of 50 kOe or more, a bisphenol type epoxy resin, a novolac type epoxy resin, an aromatic amine type epoxy resin curing agent, and a third type. It is characterized in that it is obtained by press-molding a resin-bonded magnet composition containing an amine salt epoxy resin curing agent as an active ingredient, followed by heat curing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION 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, Sm-Co ₅ system, Sm ₂ (CoFeZr
V) Rare earth cobalt type such as ₁₇ type, Nd-Fe-Co-B
Rare earths such as Nd-Dy-Fe-B and Nd-Fe-B
Iron-boron system, Sm-Fe-N system, Nd-Fe-Ti-N system,
Nd-Fe-VN system nitride magnetic powder and the like can be mentioned. In any case, the particle size of the magnetic powder is usually preferably 35 mesh (JIS) or less.

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 is, for example, bisphenol A type, bisphenol F type, bisphenol AD type and other bisphenol type epoxy resins and cresol novolac type and phenol novolac type novolak type epoxy resin as the main ingredients. It is characterized by containing. Of course, these can be used in any liquid state, solid state, semi-solid state at room temperature without particular restrictions on molecular weight, molecular weight distribution, side chains and functional groups, and in some cases, a reactive diluent or a general organic solvent may be used. You may use it in the mixed state. Moreover, these epoxy resin base compounds may be used alone or in a mixture of two or more.

Further, it is difficult to specify an appropriate amount of the 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. However, it is generally 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. The mechanical strength of the resin-bonded magnet is impaired even if the amount used is more than 5 parts by weight or less than 0.1. These curing agents can be used alone or in a state of being dissolved in an organic solvent such as acetone or methyl ethyl ketone.

Examples of such aromatic amine-based curing agents include m-phenylenediamine, p, p'-diaminodiphenylmethane, p, p'-diaminodiphenylsulfone, metaxylenediamine, xylenediamine, 1,
A curing agent generally called aromatic polyamine or aromatic amine, such as 3-bis (aminomethyl) cyclohexane, can be used without restriction on molecular weight, molecular weight distribution, side chain, functional group and the like. Of course, these modified products and the like can also be used.

Further, it is difficult to define an appropriate amount of the tertiary amine salt epoxy resin curing agent because the epoxy equivalent and active hydrogen equivalent differ depending on the type of the epoxy resin and the type of the aromatic amine type curing agent. However, it is generally 0.01 to 10 per 100 parts by weight of the magnetic powder.
Preference is given to using parts by weight, in particular 0.1 to 5 parts by weight. Even if it is used in an amount larger than 5 parts by weight,
Even if it is used in a smaller amount than 1, the mechanical strength of the resin-bonded magnet is impaired. These curing agents can be used alone or in a state of being dissolved in an organic solvent such as acetone or methyl ethyl ketone.

As such a tertiary amine salt epoxy resin curing agent, a tertiary amine curing agent may be modified into a salt to suppress the activity at room temperature to raise the melting point. What you get. Examples of these curing agents include the trade name Amicure, which is commercially available from Ajinomoto Co., Inc. Generally, these can be used without restriction on molecular weight, molecular weight distribution, side chains, functional groups and the like. Of course, these modified products and the like can also be used.

Further, in addition to the above magnetic powder and resin binder, if necessary, known Si-based, Ti-based or Al-based chemically-bonded surface treatment 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, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (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, etc., and improve the adhesion between the magnet powder and the resin binder.

The resin-bonded magnet composition is 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 acetone or methyl ethyl ketone to prepare a magnetic powder. After mixing with a wet method for obtaining a composition by drying, for example, a dry method of collectively mixing the 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. But it's okay. 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 with various compression molding apparatuses, heating it to cure the binder component, 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 performed at a temperature of 130 to 160 ° C. for 1 to 4
It may be allowed to react in about time.

In the composition of the present invention, since a bisphenol type epoxy resin, a novolac type epoxy resin, an aromatic amine type epoxy resin curing agent and a tertiary amine salt epoxy resin curing agent are used as a binder resin, a magnetic powder and a resin are used. At the same time that the adhesive strength of the layer is remarkably increased, the curing reaction rate is increased and the molecular network structure after the curing reaction becomes dense, so that it is considered that excellent mechanical strength can be obtained. Further, since it hardens at a low temperature, deterioration of magnetic properties is avoided, and it is considered that a desired high magnetic property magnet can be obtained.

[0020]

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, USA) Anisotropic magnetic field: 70.4 kOe B epoxy resin-epoxy resin (I) : (Bisphenol A type epoxy resin) (Brand name: Epotote YD-013, manufactured by Tohto Kasei Co., Ltd.) ・ Epoxy resin (II): (Phenol novolac type epoxy resin) (Brand name: Araldite EPN1138, Nippon Chiba Geiger Co., Ltd.) C) Curing agent (I) i) Aromatic amine-based epoxy resin curing agent (trade name: Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) D Curing agent (II) i) Tertiary amine salt epoxy resin curing agent ( Product name: Amicure MY-24, manufactured by Ajinomoto Co., Inc. E Hardener (III) i) Other hardener (dicyandiamide) (Brand name: DICY7, oiled shell Epoxy Co., Ltd.) F curing catalyst (trade name: Curezol OR, Shikoku Chemicals Co., Ltd.)

The compositions of Examples and Comparative Examples are shown in Tables 1 to 3. The composition was adjusted by blending the amounts of the resin and the curing agent shown in Tables 1 to 3 and diluting 10 times with methyl ethyl ketone.
It was added to 100 parts by weight of magnetic powder. After stirring a mixture of magnetic powder and a solution obtained by diluting a resin or the like, at 30 ° C. for 10 ^−1.
Methyl ethyl ketone was completely evaporated under reduced pressure of Torr to obtain each composition.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

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. The obtained molded body had a rectangular parallelepiped shape with a length of 10 mm, a width of 15 mm, and a thickness of 5 mm. This molded sample was heat-treated at the temperature and time shown in the table to cure the binder resin in the sample to obtain a resin-bonded magnet sample. Next, the magnetic characteristics of these samples were measured at room temperature with a Thiophie type self-recording magnetometer. The results of (BH) _max (maximum magnetic energy product) among the magnetic properties are shown in Tables 1 to 3. Next, the same composition as described above was fed into a ring mold and press-molded at a molding surface pressure of 7 t / cm ² , and the outer diameter was φ8 mm and the inner diameter was φ.
A cylindrical shaped body having a size of 6 mm and a height of 4 mm was obtained. Each of these molded bodies was heat-treated under the same conditions to cure the binder resin in the sample and obtain a sample for ring radial crushing strength measurement. The ring radial crushing strength of the sample was set to a head speed of 10 mm / min using an autograph manufactured by Shimadzu Corporation,
Obtained at room temperature. The results are shown in Tables 1 to 3.

Further, the composition obtained above is treated at 40 ° C.
Store in an oven and measure the ring radial crushing strength after 4 months by the same method as above. Strength retention (%) = (ring radial crushing strength after 6 months)
The strength retention rate was calculated by the formula: / (ring radial crushing strength immediately after composition adjustment) × 100. The results are shown in Tables 1 to 3.

It is sufficient that the (BH) _max (maximum magnetic energy product) of the magnet is 8 MGOe or more. Further, if the ring radial crushing strength is 5.0 gf or more, the mechanical strength is sufficient. Further, it is sufficient that the storage characteristic is 95% or more. From the results of Tables 1 to 3, it can be seen that the resin-bonded magnet of the present invention is excellent in magnetic characteristics, storage characteristics, and mechanical strength.

[0029]

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 (2)

[Claims] 1. 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 comprises a bisphenol epoxy resin and a novolac epoxy resin. A resin-bonded magnet composition, comprising an aromatic amine-based epoxy resin curing agent and a tertiary amine salt epoxy resin curing agent as active ingredients. 2. A magnetic powder having an anisotropic magnetic field of 50 kOe or more, a bisphenol type epoxy resin, 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 a resin-bonded magnet containing a tertiary amine salt epoxy resin curing agent as an active ingredient, followed by heat curing.