JPH0774013A - Composition for resin-bonded magnet and resin-bonded magnet using the same - Google Patents

Abstract

PURPOSE:To improve the magnetic characteristics of magnet and ring radial crushing strength by permitting resin binder, which contains three types of epoxy resin major agents such as novolac type epoxy resin and epoxy resin provided with polysulfide skeleton in the molecule principal chain, to contain magnetic powder which has the anisotropic magnetic field of the specified value or more. CONSTITUTION:Magnetic alloy powder which is normally used for resin-bonded magnet can be used as magnetic powder. Magnetic powder with 50kOe anisotropic magnetic field (HA) or more is especially used so as to provide resin-bonded magnet of better magnetic characteristics. Epoxy resin to be used as one ingredient of the resin binder is bisphenol A epoxy resin, novolak epoxy resin and epoxy resin which has a polysulfide skeleton in the molecule principal chain. The usage without limits of molecule quantity, molecule quantity distribution, side chains and functional group is allowed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Due to their excellent magnetic properties, rare earth permanent magnets are being used in a wide range of fields including general household electric appliances, communication / audio equipment, medical equipment, and general industrial equipment. Among them, the resin-bonded magnet is one in which a magnetic powder is mixed with a resin binder and press-molded.The resin-bonded magnet can be molded into a complicated shape with high dimensional accuracy as compared with a sintered magnet, It has advantages such as (2) high uniformity of quality and performance, (3) good yield and good machinability.

However, since the resin binder is used to enhance the mechanical strength after molding, for example, the ring radial crushing strength, when the compounding ratio of the resin binder is increased, the compounding ratio of the magnetic powder is reduced accordingly, so that the magnetism of the magnet is reduced. It has the disadvantage of inferior characteristics.

On the other hand, in recent years, small motors, audio equipment, O
The resin-bonded magnets used in equipment A, etc. are required to have high magnetic properties due to the demand for miniaturization of equipment, and mechanical strength that does not cause cracks or chips during assembly, especially strength of ring radial crushing. There is. Therefore, the ratio of the resin binder cannot be made too high. It has been proposed to use an epoxy resin as a binder in order to satisfy such contradictory requirements of improving magnetic properties and improving mechanical strength. When an epoxy resin is used as a binder, it is possible to improve magnetic properties without impairing ring radial crushing strength, heat resistance, and moldability.

[0005]

However, if only a single epoxy resin is used as a binder, there is a limit to the improvement of mechanical strength. Therefore, there has been a strong demand for a resin-bonded magnet having a ring radial crushing strength that can sufficiently withstand even a thin molded product or the like in order to improve the magnetic characteristics.

Therefore, an object of the present invention is to provide a resin-bonded magnet composition which is excellent in the magnetic properties and ring radial crushing strength of the obtained magnet even if the compounding ratio of the resin binder is kept low. Another object of the present invention is to provide a resin-bonded magnet obtained from the above composition.

[0007]

According to the present invention, a resin containing a bisphenol A type epoxy resin, a novolac type epoxy resin, and three types of epoxy resin base compounds, that is, an epoxy resin having a polysulfide skeleton in the main chain of the molecule. There is provided a composition for a resin-bonded magnet, which comprises a binder or a resin binder containing the above aromatic amine-based curing agent and magnetic powder having an anisotropic magnetic field of 50 kOe or more.

Further, according to the present invention, there is provided a resin-bonded magnet obtained by press-molding the composition and then heat-curing the composition.

A. Magnetic Powder In the present invention, as the magnetic powder, a magnetic alloy powder usually used for resin-bonded magnets can be used, but in order to obtain a resin-bonded magnet with more excellent magnetic properties, among them, Anisotropy field (H _A ) is 50 kOe
The above magnetic powder, for example, Sm-Co ₅ system, Sm ₂ (C
o, Fe, Zr, V) _17- based rare earth cobalt-based magnetic powder, Nd-Fe-Co-B-based, Nd-Dy-Fe-B-based, N
Rare earth-iron-boron magnetic powder such as d-Fe-B system, Sm-F
It is desirable to use an e-N-based, Nd-Fe-Ti-N-based, Nd-Fe-VN-based nitride magnetic powder or the like. In the present invention, it is desirable that the particle size of the above magnetic powder is usually less than or equal to the total size of JIS sieve # 35.

Among the magnetic powders exemplified above, rare earth elements
As the iron-boron magnetic powder, it is particularly preferable to use the one obtained by the liquid quenching method. In this liquid quenching method, an alloy having a required composition is melted by a method such as high frequency induction heating, and the obtained molten metal is sprayed onto a high-speed rotating copper or aluminum roll to be rapidly cooled to a thickness of several tens of μm.
And the ribbon. Apply appropriate heat treatment to this ribbon,
For example, the target magnetic powder is obtained by subjecting the average crystal grain size to 3000 A or less and then performing dry or wet pulverization using a stamp mill, a ball mill or the like.

B. Resin Binder The epoxy resin used as one component of the resin binder is a bisphenol A type epoxy resin, a novolac type epoxy resin, or an epoxy resin having a polysulfide skeleton in the main chain of the molecule, particularly, the molecular weight and the molecular weight distribution. It can be used without any restrictions such as side chains and functional groups. The novolac type epoxy resin may be either cresol novolac type or phenol novolac type. In addition to these epoxy resins, as a fourth component or more, for example, a glycidyl ether type epoxy resin, a linear aliphatic epoxide type epoxy resin, an aliphatic epoxide type epoxy resin, etc., alone or in combination of two or more, added You may mix.

The components of the resin binder are used as they are or in the state of being dissolved in an organic solvent such as acetone or methyl ethyl ketone. The amount of the novolac type epoxy resin and the amount of the epoxy resin having a polysulfide skeleton in the main chain in the molecule are 5 parts by weight or more and 950 parts by weight or less, and preferably 100 parts by weight of the bisphenol A type epoxy resin, respectively. 10 parts by weight or more 90
It is 0 parts by weight or less. The amount of each epoxy resin is 5
It is difficult to obtain sufficient ring radial crushing strength when the amount is less than the weight part or when the amount is more than 950 parts by weight.

When an aromatic amine type epoxy resin curing agent is used, it is added in an amount of 1 part by weight or more and 40 parts by weight or less, preferably 10 parts by weight or more and 30 parts by weight or less, based on 100 parts by weight of the total amount of the epoxy resin main agent. The total amount of the resin binder main agent in the composition is preferably 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight, as the total amount of the epoxy resin per 100 parts by weight of the magnetic powder.

C. Other Components In addition to the above-mentioned essential components, the resin-bonded magnet composition of the present invention may optionally contain additives known per se, such as S.
An i-based, Ti-based or Al-based chemically-bonded surface treatment agent (coupling agent), a curing accelerator (curing catalyst), or the like can be used. For example, as typical ones of the chemical bond type surface treatment agent, vinyltriethoxysilane, 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 (dioctyl pyrophosphate) ) Titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (ditridecyl phosphite)
Examples thereof include titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, acetoalkoxyaluminum diisopropylate, and the like. These are the dry method,
By mixing by a wet method, an integral blend method, or the like, it is possible to improve the adhesion between the magnetic powders in the obtained resin-bonded magnet.

Examples of the curing accelerator include tertiary amines, imidazoles, organic metal salts, chlorides, organic peroxides and the like. Resin curing agents and effect accelerators
You may use it in combination of 2 or more types as needed.

D. Preparation of Composition The composition of the present invention is obtained by mixing the required components. The mixing method is not particularly limited, for example, a wet method in which an organic component is dissolved in an organic solvent such as methyl ethyl ketone, mixed with magnetic powder and then dried to obtain a composition, for example, a ribbon blender, a Nauter mixer, a Henschel mixer, a super mixer. Alternatively, a dry method in which the required components are mixed together in a mixer such as a high speed mixer may be used. The composition thus obtained is in powder form.

E. Manufacture of Magnet In the manufacture of a magnet, the composition is press-molded by various compression molding apparatuses, and then heat treatment is applied to cure the resin binder. Then, the resin-bonded magnet is obtained by magnetizing in a magnetic field. Press molding of the composition is usually
The resin binder may be cured at a pressure of 4 to 8 t / cm ² and cured at a temperature of 150 to 200 ° C. for about 0.5 to 4 hours.

[0018]

The composition of the present invention comprises, as a resin binder, a mixture of a bisphenol A type epoxy resin, a novolac type epoxy resin, an epoxy resin having a polysulfide skeleton in the main chain in the molecule and, if necessary, an aromatic amine curing agent. Since each of these components is used, a higher polymerization rate is obtained when it is cured, and the adhesive strength between the magnetic powder and the resin layer is significantly increased, compared with the case where each of these components is used alone. It is thought that strength can be obtained.

[0019]

EXAMPLE A composition for resin-bonded magnet of the present invention and a magnet using the same were produced and evaluated. In the following examples, the following materials were used.

I Magnetic powder Magnetic powder 1: Nd-Fe-B magnet powder (trade name: MQP-
B, manufactured by General Motors, USA) Anisotropic magnetic field: 70.4kOe Magnetic powder 2: Sm-Co ₅ type magnetic powder (trade name: RCo ₅ alloy, Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 246kOe, average grain Diameter 10 μm

II Epoxy resin i) Bisphenol A type epoxy resin (trade name: Epotote YD-7011, manufactured by Tohto Kasei Co., Ltd.) ii) Cresol novolac type epoxy resin (trade name:
EOCN-1025, manufactured by Nippon Kayaku Co., Ltd.) iii) Epoxy resin having a polysulfide skeleton in the main chain of the molecule (trade name: Flep 10, manufactured by Toray Thiokol Co., Ltd.)

III Hardener a) Aromatic amine epoxy resin hardener (trade name: H
T-972, manufactured by Nippon Ciba-Geigy Co., Ltd.) a) Dicyandiamide

Examples 1 to 23, Comparative Examples 1 to 4 ...
According to the formulations shown in Tables 1 to 5, each epoxy resin main agent and curing agent were diluted 10 times with methyl ethyl ketone, and this solution was added to magnetic powder and mixed and stirred. Then 3
At 0 ° C., methyl ethyl ketone was completely volatilized under reduced pressure of 10 ⁻¹ Torr to obtain a desired resin-bonded magnet composition.

Each composition obtained above was fed into a press die and press-molded at a molding surface pressure of 5.7 t / cm ² , and the length was 1 mm.
A plate-shaped pressed body having a thickness of 0 mm, a width of 15 mm and a thickness of 5 mm was obtained. The composition using the magnetic powder 2 was molded in a magnetic field. Then, press the pressed body in the atmosphere at 145 ° C.
Heat for 1 hour to cure the resin binder in the sample,
A resin-bonded magnet was obtained. The magnetic characteristics of the obtained magnet were measured at room temperature using a Thiophie type self-recording magnetometer. The measurement results of the maximum magnetic energy product ((BH) max) are shown in Tables 1 to 5. The magnetic properties of the resin-bonded magnet require that the maximum magnetic energy product be 10 MGOe or more.

Further, each composition is supplied into a press die,
By press molding at a molding surface pressure of 5 t / cm ² , a ring-shaped resin-bonded magnet having an outer diameter of 34 mm, an inner diameter of 32 mm and a height of 8 mm was obtained in the same manner as above. Next, the ring radial crushing strength of this ring-shaped magnet was crushed using an autograph manufactured by Shimadzu Corp. at a head speed of 1 mm / min at room temperature to measure the maximum breaking strength. The radial crushing strength was used. The results are shown in Tables 1 to 5. The ring radial crushing strength of the resin-bonded magnet needs to be 4 gf or more. In the above table, the numerical values in the formulation are parts by weight.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

[Table 5]

From the above results, it is understood that the resin-bonded magnet using the resin-bonded magnet composition of the present invention is excellent in both magnetic characteristics and ring radial crushing strength.

[0032]

The resin-bonded magnet composition of the present invention is excellent in magnetic properties and ring radial crushing strength of the obtained magnet, so that it can be widely applied to general household appliances, communication / audio equipment, medical equipment, and general industrial equipment. It is expected that the usage range will be expanded in the field.

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Claims (4)

[Claims] 1. A resin binder containing three kinds of epoxy resin main ingredients, a bisphenol A type epoxy resin, a novolac type epoxy resin, and an epoxy resin having a polysulfide skeleton in the main chain of the molecule, and an anisotropic magnetic field of 50 k.
A composition for a resin-bonded magnet, which contains a magnetic powder of Oe or more. 2. A resin binder containing a bisphenol A type epoxy resin, a novolac type epoxy resin, three types of epoxy resin main agents of an epoxy resin having a polysulfide skeleton in the main chain in the molecule, and an aromatic amine curing agent. And a composition for a resin-bonded magnet, which contains magnetic powder having an anisotropic magnetic field of 50 kOe or more. 3. A resin binder containing three kinds of epoxy resin base compounds, a bisphenol A type epoxy resin, a novolac type epoxy resin, and an epoxy resin having a polysulfide skeleton in the main chain in the molecule, and an anisotropic magnetic field of 50 k.
A resin-bonded magnet obtained by pressure-molding a composition for resin-bonded magnet containing a magnetic powder of Oe or more and then heating and curing the composition. 4. A resin binder containing a bisphenol A type epoxy resin, a novolac type epoxy resin, three types of epoxy resin main agents of an epoxy resin having a polysulfide skeleton in the main chain of the molecule, and an aromatic amine curing agent. And a resin-bonded magnet obtained by press-molding a composition for resin-bonded magnet containing a magnetic powder having an anisotropic magnetic field of 50 kOe or more, followed by heat curing.