JPH0696923A - Composition for bond magnet and its manufacture - Google Patents

Abstract

PURPOSE:To improve the powder fluidity of a composition without spoiling its magnetic characteristic by making the composition contain magnetic alloy powder, silicon dioxide, at least one kind of thermosetting resin, and binder having a specific kinetic viscosity. CONSTITUTION:In this manufacturing method, a composition for bond magnet is manufactured in such a way that, after a binder having a <=1X10<-3>m<2>/S kinetic viscosity (at 25 deg.C) in 70wt.% Butyl Carbitol solution measured by the Gardner method is mixed with a mixture of magnetic alloy powder and one kind of thermosetting resin, silicon dioxide is mixed with the mixture at a rate of 0.01-5wt.% per 100wt.% of magnetic alloy powder. The bond magnet is obtained by press-molding the composition and hardening the molded product by heating. Therefore, the composition for bond magnet having an excellent magnetic characteristic and fluidity can be manufactured at high productivity. In addition, the bond magnet obtained from this composition becomes suitable for mass production.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bond magnet composition having excellent moldability and a bond magnet having excellent magnetic properties obtained from the composition.

[0002]

2. Description of the Related Art Rare earth permanent magnets are being used in a wide range of fields from their excellent magnetic properties to general home appliances, communication / audio equipment, medical equipment, and general industrial equipment. Among them, the bond type magnet is formed by mixing magnetic powder with a resin binder and press-molding.Therefore, as compared with the sintering type magnet, (1) dimensional accuracy is high and it can be molded into a complicated shape. It has advantages such as (2) high uniformity of quality and performance, (3) good yield and good machinability. However, on the other hand, since a resin binder is used, the magnetic properties of the magnet are impaired.

Recently, a bond obtained by using an epoxy resin which is liquid at room temperature as a resin binder, which satisfies the contradictory requirements of improving the magnetic properties and the mechanical properties of a magnet. Magnets have been proposed. That is, by using such an epoxy resin, it is possible to improve the magnetic properties of the magnet without suppressing the ratio of the resin to a low level, and it is possible to obtain a bonded magnet having good mechanical properties such as strength.

[0004]

However, if only the epoxy resin which is liquid at room temperature is used as the binder, the powder fluidity of the composition to be press-molded is lowered and the press-molding becomes difficult and the mass productivity becomes low. There is a new problem of being seriously damaged.

Therefore, an object of the present invention is to provide a composition for a bonded magnet having improved powder fluidity without impairing magnetic properties, and a method for producing the same. Another object of the present invention is to provide a bonded magnet obtained from the above composition.

[0006]

According to the present invention, 100 parts by weight of magnetic alloy powder, 0.01-5 parts by weight of silicon dioxide, and at least one thermosetting resin are used and 70% by weight of butyl carbitol is used. Provided is a composition for a bonded magnet, which contains a binder having a kinematic viscosity (25 ° C.) in a solution of 1 × 10 ⁻³ m ² / s or less by Gardner method.

Further, according to the present invention, the kinematic viscosity (25 ° C.) by the Gardner method in a 70 wt% butyl carbitol solution, which comprises magnetic alloy powder and at least one thermosetting resin, is 1 × 10 ⁻³ m. Provided is a method for producing a bond magnet composition, which comprises mixing 0.01 to 5 parts by weight of silicon dioxide powder per 100 parts by weight of the magnetic alloy powder after mixing with a binder having a ratio of ² / s or less. .

According to the present invention, there is further provided a bond magnet obtained by press-molding the composition for a bond magnet and then heat-curing the composition.

Magnetic Powder In the present invention, as the magnetic powder, a magnetic alloy powder which is usually used in bonded magnets can be used, but in order to obtain a bonded magnet having more excellent magnetic properties, it is particularly different. Magnetic powder with an anisotropic magnetic field (HA) of 50 kOe or more,
For example, rare-earth cobalt-based magnetic powders such as Sm ₁ -Co ₅ system and Sm ₂ (CoFeZrV) ₁₇ system, Nd-Fe-Co-B system, Nd-Dy- system.
Fe-B type, Nd-Fe-B type rare earth-iron-boron type magnetic powder, Sm-Fe-N type, Nd-Fe-Ti-N type, Nd-Fe-V-
It is desirable to use N-based nitride magnetic powder or the like. In the present invention, the particle size of the magnetic powder is preferably usually 35 mesh (JIS) or less.

Among the magnetic powders exemplified above, it is particularly preferable to use the rare earth-iron-boron magnetic powder obtained by the liquid quenching method. This liquid quenching method melts the alloy of the required composition by a method such as high frequency induction heating, sprays the resulting melt on a high-speed rotating copper or aluminum roll to quench it, and forms a ribbon with a thickness of several tens of microns. To do. The ribbon is subjected to an appropriate heat treatment to, for example, an average crystal grain size of 3000 Å or less, and then dry or wet pulverized using a stamp mill, a ball mill or the like to obtain the target magnetic powder.

Silicon dioxide powder In the present invention, it is extremely important to use silicon dioxide powder in combination with the above magnetic powder. That is, when the magnetic powder is mixed with a binder described later and then silicon dioxide powder is mixed therein, the silicon dioxide powder exists in a state of being sprinkled around the binder coated with the magnetic powder (this is observed by an electron microscope. As a result of this,
It is believed that the powder flowability of the magnet composition is improved.

Examples of the silicon dioxide powder include fumed silica, pyrogenic silica, precipitated silica, pulverized silica,
Any of fused silica and surface-treated silica obtained by treating the surface of these with an appropriate agent can be used, but generally contains 50% by weight or more of particles having a particle size of 20 μm or less, and has a maximum particle size of It is preferably 200 μm or less. For example, if the content of particles of 20 μm or less is less than 50% by weight, it is necessary to use an extremely large amount of silicon dioxide powder in order to improve the powder fluidity of the composition. The characteristics and mechanical strength tend to decrease.

The amount of silicon dioxide powder used is the same as that of the magnetic powder.
It is set in the range of 0.01 to 5 parts by weight, particularly 0.1 to 1 part by weight, per 100 parts by weight. If less than 0.01 parts by weight,
Good powder fluidity cannot be obtained, and when it is used in an amount larger than 5 parts by weight, magnetic properties and mechanical strength are deteriorated.

Binder At least one kind of thermosetting resin is used as the binder. In the present invention, the binder is 70
It is necessary that the kinematic viscosity (25 ° C.) in the wt% butyl carbitol solution by the Gardner method is 1 × 10 ⁻³ m ² / s or less. That is, the kinematic viscosity of the binder is 1 × 10 ^−3.
When it is higher than m ² / s, the powder fluidity of the composition for a bonded magnet is improved, but voids are apt to occur in a molded body obtained by press molding described later, and therefore the density of magnetic powder can be improved. However, the magnetic properties of the resulting bonded magnet will be unsatisfactory.

In the present invention, various kinds of thermosetting resins can be used as the binder-forming thermosetting resin, for example, various types such as glycidyl ether type, glycidyl ester type, glycidyl amine type, linear aliphatic epoxide type and the like. Examples of various imide resins such as epoxy resin, amino bismaleimide, bismaleimide triazine, imide ether, phenylated imide thiophene, silicone modified imide, and fluorine-containing imide, phenol resin, amino resin, diallyl phthalate resin, unsaturated polyester resin. You can These may be used in combination of two or more as long as the above-mentioned kinematic viscosity is satisfied.

The above-mentioned binder is preferably used in an amount of 0.5 to 5 parts by weight, particularly 1 to 3 parts by weight, per 100 parts by weight of the magnetic powder. If it is used in an amount greater than 5 parts by weight, the magnetic properties of the bonded magnet will be impaired, and if it is less than 0.5 part by weight, the mechanical strength of the bonded magnet will be impaired.

Other Components In the composition for a bonded magnet of the present invention, in addition to the above-mentioned essential components, if necessary, an additive known per se, for example, a Si-based, Ti-based or Al-based chemically bonded surface is used. A treating agent (coupling agent), a resin curing agent, a curing accelerator (curing catalyst), etc. can be used.

For example, as typical ones of the above chemical bond type surface treatment agents, 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, isopropyl tris (dioctyl pyrophosphate) titanate,
Isopropyltri (N-aminoethyl-aminoethyl)
Examples thereof include titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate, acetoalkoxy aluminum diisopropylate and the like. By mixing these by a dry method, a wet method, an integral blend method, or the like, it is possible to improve the adhesion between the magnetic powders in the obtained bonded magnet.

Examples of the resin curing agent include 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 type curing agent, and a cationic polymerization type. A hardening agent etc. can be illustrated. Examples of the curing accelerator include tertiary amines, imidazoles, organic metal salts, various chlorides, organic peroxides and the like. These resin curing agents and curing accelerators are used singly or in combination of two or more, depending on the type of thermosetting resin used as a binder.

Composition for Bonded Magnet The composition for bonded magnet of the present invention is obtained by mixing the above-mentioned magnetic alloy powder and a binder, and then mixing silicon dioxide powder. In this case, it is preferable that optional components such as various surface treatment agents, resin curing agents, and curing accelerators are mixed with the binder, and finally the silicon dioxide powder is mixed. As a result, the silicon dioxide powder is sprinkled on the surface of the binder coating the magnetic alloy powder, and good powder fluidity is secured.

The mixing method of each component is not particularly limited, for example, a ribbon blender, a tumbler, a Nauter mixer,
It can be performed using a mixer such as a Henschel mixer or a super mixer, and the composition for a bonded magnet can be prepared by using either a wet method or a dry method. The wet method is a method in which an organic component such as a thermosetting resin serving as a binder is dissolved in an appropriate organic solvent such as methyl ethyl ketone, and this is mixed with magnetic powder and dried, and then silicon dioxide powder is mixed to obtain a composition. Is. The dry method is
This is a method of preparing a composition by mixing the components other than the silicon dioxide powder all at once using the above-mentioned mixer or the like and then mixing the silicon dioxide powder. The composition for a bonded magnet thus obtained uses a thermosetting resin binder having a specific kinematic viscosity, and since the surface of the binder is sprinkled with a silicon dioxide powder, it has no tackiness and is extremely fluid. It becomes a highly powdery composition.

Bonded Magnet The above-mentioned composition for bonded magnet is obtained by press-molding using various compression-molding devices, heat treatment to harden the binder, and then magnetizing in a magnetic field, if necessary. A bonded magnet can be obtained. The press molding is usually performed under a pressure of 4.0 to 8.0 t / cm ² , and the heat treatment is generally performed at a temperature of 120 to 190 ° C. for 0.5 to 3 hours, although it varies depending on the kind of the binder used. Magnetization in a magnetic field can also be performed simultaneously with press molding, for example. The bond magnet thus obtained has a high density and high magnetic properties, and is also excellent in mechanical properties such as strength.

[0023]

EXAMPLES In the following examples, the following materials were used as materials for bonded magnets.

Magnetic powder Magnetic powder 1: Nd-Fe-B magnet powder (trade name: MQP-
B, made by US General Motors), anisotropic magnetic field: 70.4
kOe, average particle size: 200 μm Magnetic powder 2: Sm / Co ₅ system magnet powder (trade name: RCo ₅ alloy,
Sumitomo Metal Mining Co., Ltd.), anisotropic magnetic field: 246 kOe, average particle size: 10 μm

Thermosetting resin Bisphenol A type epoxy resin Product name: Araldite GY260, manufactured by Nippon Ciba Geigy Co., Ltd. (completely liquid at 25 ° C) Bisphenol A type epoxy resin Product name: Araldite GY280, manufactured by Nippon Ciba Geigy Co., Ltd. (25 ° C It is a semi-solid and has a kinematic viscosity of ^{4 to} 6.27 × 10 ^-4 m ² / s in a 70 wt% butyl carbitol solution at the same temperature. Cresol novolac type epoxy resin Product name: Araldite ECN1273, Nippon Ciba Geigy Stock Company made (solid at 25 ° C) Bismaleimide triazine resin Product name: BT3109, Mitsubishi Gas Chemical Co., Ltd. (completely liquid at 25 ° C)

Silicon dioxide powder a) Trade name: Nipseal SS-50, manufactured by Nippon Silica Industry Co., Ltd. Content of particles of 20 μm or less: 100% by weight Average particle size: 1-2 μm, maximum particle size: 10 μm b) Product name : Syloid # 150, manufactured by Fuji Davisson Chemical Co., Ltd. Content of particles of 20 μm or less: 100% by weight Average particle size: 1.4 μm, maximum particle size: 10 μm

Hardener 4,4'-diaminodiphenyl sulfone Product name: Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.

Examples 1 to 10 and Comparative Examples 1 to 4 According to the formulations shown in Tables 1 to 3, a solution prepared by diluting a thermosetting resin and a curing agent by 10 times with methyl ethyl ketone was added to magnetic powder and mixed. It was stirred. Then, at 30 ° C., methyl ethyl ketone was completely volatilized under reduced pressure (10 ⁻¹ Torr), silicon dioxide powder was added according to the formulation shown in Tables 1 to 3, and mixing and stirring were performed again.
The desired composition for bonded magnets was obtained. Incidentally, in the composition of each example, only the thermosetting resin used,
The kinematic viscosity of 70% by weight butyl carbitol solution was measured by the Gardner method at 25 ° C, and the measured value was 1 × 10 ^-3 m ² / s.
The following items are shown in Tables 1 to 3 by ◯ and those higher than 1 × 10 ⁻³ m ² / s as x. In addition, Example and Comparative Example 1,
The compositions obtained in Examples 2 and 3 were smooth and highly fluid, but the composition of Comparative Example 4 exhibited tackiness that easily aggregated. The powder fluidity of each composition was measured as follows, and the results are shown in Tables 1 to 3. Measurement of powder fluidity; mold the composition (outer diameter 20 mmφ, inner diameter 18
(mmφ, depth 35 mm) and powdered, and the amount of powder in the mold was weighed. If the amount of powder is 3g or more, ○, 2g or more, 3g
Less than was judged as Δ and less than 2 g was judged as x.

Each composition obtained above was fed into a press mold and press-molded at a molding surface pressure of 5.7 ton / cm ² to obtain a length of 80 mm.
A plate-like sample having a width of 10 mm and a thickness of 4 mm was obtained (the composition using the magnetic powder 2 was molded in a magnetic field). Next, this plate-shaped sample was heat-treated in the atmosphere at 180 ° C. for 2 hours to cure the binder in the sample to obtain a bonded magnet. The magnetic properties of the obtained bonded magnet were measured at room temperature using a Thiophy type self-recording magnetometer, and the measurement results are shown in Table 1.
~ 3.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

In the above table, the numerical values in the formulation are
Parts by weight.

[0034]

EFFECT OF THE INVENTION The composition for bonded magnets of the present invention is not only excellent in magnetic properties of the obtained magnet, but also extremely good in powder fluidity, excellent in molding workability and high in productivity. It has advantages and is very suitable for mass production.
Bonded magnets obtained from this composition are general household appliances,
The range of applications is expected to expand in a wide range of fields, including communication / audio equipment, medical equipment, and general industrial equipment.

Claims (4)

[Claims] 1. A kinematic viscosity by a Gardner method in a 70 wt% butyl carbitol solution consisting of 100 parts by weight of a magnetic alloy powder, 0.01 to 5 parts by weight of silicon dioxide powder, and at least one thermosetting resin (25 A composition for a bonded magnet containing a binder having a temperature of 1 × 10 ⁻³ m ² / s or less. 2. The composition for a bonded magnet according to claim 1, wherein the magnetic alloy powder is coated with a binder, and the silicon dioxide powder is present in a state of being sprinkled on the surface of the binder. 3. A magnetic alloy powder and at least one thermosetting resin, and a kinematic viscosity (25 ° C.) by a Gardner method in a 70 wt% butyl carbitol solution is 1 × 10 ⁻³ m.
^A method for producing a bond magnet composition, which comprises mixing 0.01 to 5 parts by weight of silicon dioxide powder per 100 parts by weight of the magnetic alloy powder after mixing with a binder having a ratio of ² / s or less. 4. A kinematic viscosity by a Gardner method consisting of 100 parts by weight of magnetic alloy powder, 0.01 to 5 parts by weight of silicon dioxide powder, and at least one thermosetting resin and in a 70% by weight butyl carbitol solution (25). A bonded magnet obtained by pressure-molding a composition for a bonded magnet containing a binder having a temperature of 1 × 10 ⁻³ m ² / s or less and then heat-curing the composition.