JPH06120018A - Bonded magnet composition and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a bonded magnet composition having improved powder fluidity without impairing magnetic characteristics by a method wherein the mixture, consisting of specific magnetic alloy powder, silicon dioxide powder, dicyandiamide powder and at least a kind of thermosetting resin, is mixed with a specific binder. CONSTITUTION:A mixture is obtained by mixing magnetic alloy powder of 100 pts.wt., silicon dioxide powder of 0.01 to 5 pts.wt., dicyandiamide powder, and at least a kind of thermosetting resin. This mixture and a binder, having the kinematic viscosity, by Gardner process, (25 deg.C) of 1X10<-3>m<2>/s or lower in 70wt.% butyl carbitol solution, are mixed and a bonded magnet composition is obtained. Moreover, the magnetic alloy powder is present in the state wherein it is sprinkled on the surface of the binder. As a result, not only the obtained magnet has excellent magnetic characteristics, but also it has very good powder fluidity characteristics, it has excellent moldability, and productivity can be improved.

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 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 bond type magnet is one in which a magnetic powder is mixed with a resin binder and press-molded. Therefore, as compared with the sintered type magnet, (1) the dimensional accuracy is high and it can be molded into a complicated shape. , (2) high uniformity of quality and performance, (3) good yield, good machinability, and the like. However, on the other hand, since a resin binder is used, there is a drawback that the magnetic characteristics of the magnet are impaired.

Recently, a bonded magnet 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 mechanical properties of the magnet. Is 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, when 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, resulting in mass productivity. There is a new problem that is greatly 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
Kinematic viscosity by a Gardner method in a 70 wt% butyl carbitol solution (comprising 100 parts by weight of magnetic alloy powder, 0.01 to 5 parts by weight of silicon dioxide powder, dicyandiamide powder, and at least one thermosetting resin) 25 ° C)
There is provided a composition for a bonded magnet, which comprises a binder having a viscosity of 1 × 10 ⁻³ m ² / s or less.

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. ^A binder having a ratio of ² / s or less is mixed, and then dicyandiamide powder is mixed with the binder, and 0.01 / 100 parts by weight of the magnetic alloy powder is mixed.
Provided is a method for producing a composition for a bonded magnet, which comprises mixing ˜5 parts by weight of silicon dioxide powder.

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

A. Magnetic Powder As the magnetic powder in the present invention, a magnetic alloy powder usually used in bonded magnets can be used,
In order to obtain a bonded magnet having more excellent magnetic properties, magnetic powders having an anisotropic magnetic field (HA) of 50 kOe or more, for example, Sm—Co ₅ system, Sm ₂ (Co, Fe, Z) are particularly preferable.
r, V) _17- based rare earth cobalt-based magnetic powder, Nd-
Fe-Co-B system, Nd-Dy-Fe-B system, Nd-F
eB-based rare earth-iron-boron magnetic powder, Sm-Fe
-N type, Nd-Fe-Ti-N type, Nd-Fe-VN
It is preferable to use a system nitride magnetic powder. Further, in the present invention, it is desirable that the particle size of the magnetic powder is 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. In this liquid quenching method, an 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 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 carrying out dry or wet pulverization using a stamp mill, a ball mill or the like after setting the average crystal grain size to 3000 Å or less.

B. Silicon dioxide powder As silicon dioxide powder, the purity is 70
It can be used without any particular problem as long as it is contained in an amount of not less than wt%. Any one can be used. Generally, particles containing 50% by weight or more of particles having a particle size of 20 μm or less and having an average particle size of 20 μm or less are suitable.
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 silicon dioxide powder is used in an amount of 0.01 to 5 parts by weight, especially 0.1% by weight per 100 parts by weight of the magnetic powder.
It is set in the range of 1 to 1 part by weight. If it is less than 0.01 parts by weight, good powder fluidity cannot be obtained, and if it is used in excess of 5 parts by weight, magnetic properties and mechanical strength are deteriorated.

C. Dicyandiamide powder As the dicyandiamide powder, if it is dicyandiamide containing 50% by weight or less of particles of 20 μm or less, there are no particular restrictions on the production method, the pulverization method, the use of the secondary aggregation preventing agent and the like. If the content of particles of 20 μm or less is greater than 50% by weight, not only the fluidity of the powder is impaired, but also the mechanical strength of the obtained bonded magnet is significantly reduced.

As such dicyandiamide powder, for example, commercially available from Yuhi Shell Epoxy Co., Ltd., trade names: Epicure DICY7, Epicure DIC
There are Y15 and trade names: CG-1200, CG-1400 and the like, which are commercially available from ACI Japan Limited. These may be used alone or in combination of two or more, depending on the type of thermosetting resin used as the binder. The amount of the dicyandiamide powder added is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin, and if it is less than 5 parts by weight, the powder fluidity is reduced, and the strength of the obtained bonded magnet is reduced. If it exceeds the range, the strength of the bond magnet obtained will decrease.

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

As the thermosetting resin which constitutes the binder, various kinds can be used, for example, glycidyl ether type, glycidyl ester type, glycidyl amine type, linear aliphatic epoxide type, aliphatic epoxide type and the like. Various epoxy resins can be illustrated. These may be used in combination of two or more as long as the above-mentioned kinematic viscosity is satisfied. The binder is 0.5 to 100 parts by weight of the magnetic powder.
It is preferably used in an amount of 5 parts by weight, especially 1 to 3 parts by weight. If it is used in an amount of more 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.

E. 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 treatment agent is used. (Coupling agent), curing accelerator (curing catalyst), etc. can be used. For example, as a typical one of the 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, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (ditridecyl) Examples thereof include phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, and acetoalkoxy aluminum diisopropylate. By mixing these by a dry method, a wet method, an integral blending method, or the like, it is possible to improve the adhesion between the magnetic powders in the obtained bonded magnet.

F. Composition for Bonded Magnet The composition for bonded magnet is obtained by mixing the above-mentioned magnetic alloy powder and a binder, then mixing this with dicyandiamide powder, and further 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,
Good powder flowability is ensured.

The mixing method of each component is not particularly limited, and it can be carried out by using a mixer such as a ribbon blender, a tumbler, a Nauter mixer, a Henschel mixer, a super mixer, or the like, for example, a wet method or a dry method. The composition for bonded magnets can be prepared using either of them. In the wet method, 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 dicyandiamide powder is mixed with this, followed by further oxidation. It is a method of mixing a silicon powder to obtain a composition. The dry method is a method in which the components other than the silicon dioxide powder and the dicyandiamide powder are collectively mixed using the above-described mixer, and then the dicyandiamide powder and the silicon dioxide powder are mixed to adjust the composition.

[0020]

In the present invention, it is extremely important to use dicyandiamide powder and silicon dioxide powder in combination with the above magnetic powder. That is, the above magnetic powder is mixed with a binder to be described later, and then dicyandiamide powder is mixed therewith, and further silicon dioxide powder is mixed. It is present (which can be confirmed by electron microscopy) and as a result it is believed that the powder flowability of the magnet composition is improved. 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 silicon dioxide powder, it has no tackiness and has extremely high fluidity. It becomes a highly powdery composition.

The above-mentioned composition for bonded magnets is press-molded using various compression molding devices, then heat-treated to harden the binder, and then, if necessary, magnetized in a magnetic field to obtain a desired bond. You can get a magnet. The press molding is usually performed under a pressure of 4 to 8 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 and the curing agent used. . Also, the magnetization in a magnetic field is
For example, it can be performed simultaneously with press molding. The bond magnet thus obtained has a high density and high magnetic properties, and is also excellent in mechanical properties such as strength.

[0022]

EXAMPLES In the following examples, the following materials were used as materials for bonded magnets. I. Magnetic powder Magnetic powder 1: Nd-Fe-B based magnet powder (trade name: MQP-B, manufactured by General Motors, USA) Anisotropic magnetic field: 70.4 kOe Magnetic powder 2: Sm-Co ₅ based magnetic powder (trade name : RCo ₅ alloy, manufactured by Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 246 kOe, average particle size 10 μm

II. Thermosetting resin i) Bisphenol A type epoxy resin (trade name: Araldite GY260, manufactured by Ciba-Geigy Co., Ltd.) ii) Bisphenol A epoxy resin (trade name: Araldite GY280, manufactured by Ciba-Geigy Co., Ltd.) iii) Cresol novolac type epoxy resin Resin (Product name: Araldite ECN1273, manufactured by Nippon Ciba Geigy Co., Ltd.)

III. Silicon dioxide powder a) Brand 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) Brand name: Syloid # 150, manufactured by Fuji Devison 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

IV. Dicyandiamide powder a) Product name: CG-1400, particle size 20 μm or less 100%, sold by ACI Japan Limited Ltd.) Product name: CG-NA, particle size 20 μm or less 50% or less, ACI Japan Limited Ltd. sales

Examples 1 to 10 and Comparative Examples 1 to 6 According to the formulations shown in Tables 1 to 3, a solution prepared by diluting a thermosetting resin 10 times with methyl ethyl ketone was added to magnetic powder, and mixed and stirred. Then, at 30 ° C., methyl ethyl ketone was completely volatilized under reduced pressure (10 ⁻¹ Torr), and then dicyandiamide powder was added according to the formulation shown in Tables 1 to 3, followed by mixing and stirring, and further adding silicon dioxide powder, and again. Mixing and stirring were performed to obtain a desired composition for bonded magnet.

In each of the compositions of the examples, the kinematic viscosity of the 70% by weight butyl carbitol solution in the composition of each example was measured by the Gardner method at 25 ° C., and the measured value was 1 × 10 ⁻³ m ^2. / S or less is ○,
Those higher than 1 × 10 ⁻³ m ² / s are marked with x, and Table 1
The results are shown in Table 3.

The powder fluidity of each composition was measured, and the results are shown in Tables 1 to 3. For the measurement of powder fluidity, the composition was molded into a mold (outer diameter 20 mmφ, inner diameter 18 mmφ, depth 35 m
After powdering m) and scraping off, the amount of powder in the mold was weighed, and the powdering amount of 3 g or more was evaluated as ◯ and less than 3 g was evaluated as x.

Each composition obtained above was fed into a press mold and press-molded at a molding surface pressure of 5.7 t / cm ² to obtain a plate sample having a length of 80 mm × a width of 10 mm × a thickness of 4 mm. (The composition using the magnetic powder 2 was molded in a magnetic field). Next, this plate-shaped sample is placed in the atmosphere at 180 ° C.
Heat treatment was performed 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,
The measurement results are shown in Tables 1 to 3. In the above table, the numerical values in the formulation are parts by weight.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

EFFECTS OF THE INVENTION The composition for bonded magnets of the present invention has the advantages that not only the magnetic properties of the resulting magnet are excellent, but also the powder flow properties are extremely good, the moldability is excellent, and the productivity is high. It is extremely 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 magnetic alloy powder of 100 parts by weight and 0.0
1 to 5 parts by weight of silicon dioxide powder, dicyandiamide powder, and at least one thermosetting resin, and 70
A composition for a bonded magnet, containing a binder having a kinematic viscosity (25 ° C.) in a wt% butyl carbitol solution by the Gardner method 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 the kinematic viscosity (25 ° C.) by a Gardner method in a 70 wt% butyl carbitol solution is 1 ×.
Mixing with a binder having a concentration of 10 ⁻³ m ² / s or less, then mixing with dicyandiamide powder, and further mixing with 0.01 to 5 parts by weight of silicon dioxide powder per 100 parts by weight of the magnetic alloy powder. A method for producing a composition for a bonded magnet, comprising: 4. 100 parts by weight of magnetic alloy powder and 0.0
1 to 5 parts by weight of silicon dioxide powder, dicyandiamide powder, and at least one thermosetting resin, and 70
A composition for a bonded magnet containing a binder having a kinematic viscosity (25 ° C.) by a Gardner method in a wt% butyl carbitol solution of 1 × 10 ⁻³ m ² / s or less is pressure-molded and then heated. A bonded magnet obtained by curing.