JPH10326707A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition whose permeability is proper, whose electric insulating property is high and whose withstand voltage is excellent by a method wherein a soft ferrite powder is at leat one kind of magnetic- substance powder selected from a group composed of an Ni-Zn-based ferrite powder, an Mg-Zn-based ferrite powder and a Cu-based ferrite powder and the void ratio of the magnetic powder is set at a specific % or lower. SOLUTION: A soft ferrite powder is a compound MO.Fe2 O3 by ferric oxide Fe2 O3 and by bivalent metal oxide MO, and it is classified into an Mn-Zn-based ferrite, an Mg-Zn-based ferrite, an Ni-Zn-based ferrite, a Cu-based ferrite, a Cu-Zn-based ferrite, a Cu-Zn-Mg-based ferrite, a Cu-Ni-Zn-based ferrite and the like according to the kind of the bivalent letal oxide. As the soft ferrite powder, at least one kind of magnetic powder selected from a group composed of an Ni-Zn-based ferrite powder, an Mg-Zn-based ferrite powder and a Cu-based ferrite powder. As the soft ferrite powder, the magnetic powder whose void ratio is at 5% or lower is used. The void ratio is to be set preferably at 4% or lower, more preferably at 3% or lower and much more preferably at 2% or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition obtained by dispersing a magnetic powder of a soft ferrite in a synthetic resin, and more particularly to a resin composition having a proper magnetic permeability and a high electric insulating property, and having a high resistance to electric power. The present invention relates to a magnetic powder-containing resin composition having excellent voltage.

[0002]

In general, compounds of the metal oxide of the second iron and divalent oxidation (MO · Fe ₂ O ₃₎ is a large soft magnetic material of the magnetic permeability is called the soft (soft) ferrite I have. Soft ferrite is manufactured by powder metallurgy and is hard and lightweight. Among soft ferrites, Ni-Zn
Series ferrite, Mg-Zn series ferrite, and Cu series ferrite have high electric resistivity, and therefore have a feature of high magnetic permeability in a high frequency band, and a sintered body thereof includes a deflection yoke, a high frequency transformer, It is used as a material for magnetic heads and the like.

[0003] Soft ferrite has the disadvantage of being brittle, but taking advantage of its high electrical resistance, a soft magnetic composite material obtained by dispersing the powder in a synthetic resin is used for choke coils, rotary transformers, line filters, and the like. New applications are being developed as electromagnetic wave shielding materials (EMI shielding materials) and the like. Soft magnetic composite material is a resin composition in which soft ferrite powder is dispersed in a synthetic resin, and various molding methods generally applied in the field of synthetic resin, for example, injection molding, extrusion molding, compression molding, and the like, It can be molded into a molded article of a desired shape.

[0004] However, despite the fact that soft ferrite shows a high electric resistance (electrical insulation) in a sintered state, a resin composition in which powder obtained by pulverizing the soft ferrite is dispersed in a synthetic resin having a high electric insulation has a problem. There is a problem that they do not exhibit high electrical resistance as expected from their electrical properties. That is, a molded article formed using a resin composition containing a synthetic resin and a soft ferrite powder has a problem that electric insulation is low and the original electric insulation of soft ferrite is significantly impaired. Therefore, when the resin composition is applied to a power supply device component such as a line filter which requires a withstand voltage of 1500 V or more, there is a problem in that the resin composition generates heat during use or during a test and becomes unusable.

Conventionally, as a method for increasing the electric resistance of a resin composition containing a synthetic resin and a soft ferrite powder, for example, a resin composition containing a Ni-based ferrite powder or a Mg-based ferrite powder and a crystalline thermoplastic resin is used. Heat-treating a molded article formed from a thermoplastic resin at a temperature equal to or higher than the glass transition point of the thermoplastic resin and lower than the melting point thereof (JP-A-8-19)
9001), a method using a magnetic powder having an oxide layer formed on the surface thereof (JP-A-8-213226),
A method using a magnetic powder having a specific particle size distribution (JP-A-9-63827) has been proposed.

By the above methods (1) and (2), the withstand voltage of the resin composition containing the magnetic substance powder can be greatly improved from the conventional level. However, in the method (1), since the molded body is subjected to a heat treatment at a high temperature for a long time, thermal deformation may occur, and the dimensional accuracy of the molded body may be a problem. In addition, in the method (1), when the synthetic resin and the magnetic powder are melt-kneaded or molded, the magnetic powder is crushed, and the oxide layer (insulating layer) formed on the surface is destroyed. There was a problem. In the above method, a magnetic material powder having a specific particle size distribution is used, and therefore, depending on the application, it is necessary to use a low-modulus agent for lowering the modulus of elasticity of the resin composition. There was a case where the property decreased.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin composition containing a magnetic powder, which has an appropriate magnetic permeability, a high electric insulation and a high withstand voltage. The present inventors have conducted intensive studies to overcome the problems of the prior art, and as a result, in a resin composition containing a synthetic resin and a soft ferrite powder, Ni-Zn ferrite, Mg -Using at least one type of magnetic powder selected from the group consisting of Zn-based ferrite and Cu-based ferrite, and further reducing the porosity of the magnetic powder so as to have an appropriate magnetic permeability. In addition, they have found that a resin composition having a significantly improved withstand voltage can be obtained, and based on the findings, have completed the present invention.

[0008]

According to the present invention, there is provided a resin composition containing a synthetic resin and a soft ferrite powder, wherein the soft ferrite powder comprises a Ni--Zn ferrite;
A resin composition comprising at least one magnetic powder selected from the group consisting of Mg-Zn ferrite and Cu ferrite, and having a porosity of 5% or less. Is provided.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The soft ferrite is a ferric oxide (Fe ₂ O ₃₎ and a divalent metal oxide (MO) and the compound _{(MO · Fe 2 O 3)} , a divalent metal oxide Mn-Zn, Mg-Zn, Ni-Zn, C
u-based, Cu-Zn-based, Cu-Zn-Mg-based, Cu-Ni
-Classified into various ferrites such as Zn-based. In the present invention, at least one magnetic powder selected from the group consisting of Ni-Zn ferrite, Mg-Zn ferrite, and Cu ferrite is used as the soft ferrite powder.

The Ni—Zn ferrite is represented by the general formula (N
iO) x (ZnO) y · Fe ₂ O ₃ means a composition having a composition represented by Ni, but a part of Ni is replaced by Cu, Mg, Co, Mn.
And other divalent metals. Ni
-The Zn-based ferrite may be one to which other additives are added as long as the original properties are not impaired. Ni- in which the content of iron oxide is adjusted to suppress the precipitation of hematite
Zn-based ferrite is particularly preferred. The Mg—Zn ferrite is represented by the general formula (MgO) x (ZnO) y · Fe ₂ O ₃
Which has a composition represented by
It may be replaced by another divalent metal such as i, Cu, Co, Mn. The Mg-Zn-based ferrite may be one to which other additives are added as long as the original properties are not impaired. In order to suppress the precipitation of hematite, Mg-Zn ferrite in which the content of iron oxide is adjusted is particularly preferable.

[0011] Cu-based ferrite is represented by the general formula (CuO)
A substance having a composition represented by Fe ₂ O _3, but may be a substance in which a part of Cu is replaced with another divalent metal such as Ni, Zn, Mg, Co, and Mn. Cu-based ferrite is
Other additives may be added as long as the original characteristics are not impaired. In order to suppress the precipitation of hematite, Cu-based ferrite in which the content of iron oxide is adjusted is particularly preferable. Ni-Zn ferrite used in the present invention, Mg-
Zn-based ferrite and Cu-based ferrite can be obtained by a known method. Representative of these ferrite raw materials are Fe ₂ O ₃ , MnO ₂ , MnCO ₃ , CuO, N
Metal oxide or metal carbonate such as iO, MgO, ZnO and the like. Typical methods for producing soft ferrite include a dry method, a coprecipitation method, and a spray pyrolysis method.

In the dry method, raw materials such as oxides and carbonates of the above-mentioned elements are calculated so as to have a predetermined mixing ratio, mechanically mixed, fired, and pulverized. In the dry method, it is preferable that the raw material mixture is preliminarily calcined and pulverized into fine particles, granulated into granules, further calcined, and then pulverized again to obtain a soft ferrite powder. In the coprecipitation method, a strong alkali is added to an aqueous solution of a metal salt to precipitate a hydroxide, which is oxidized to obtain fine ferrite powder. After granulation, the ferrite powder is fired and then pulverized. In the spray pyrolysis method, an aqueous solution of a metal salt is thermally decomposed to obtain a particulate oxide. After being granulated, the oxide powder is fired and then pulverized. The fired ferrite is pulverized by a hammer mill, a rod mill, a ball mill, or the like to obtain a ferrite powder having a target particle size.

In the present invention, in order to suppress the porosity of the magnetic substance powder, a method of firing at a high temperature exceeding 1200 ° C. is preferable. Further, in order to suppress the porosity, there is a method in which an additive that promotes the solid phase reaction is used in combination. Such additives include copper compounds such as copper oxide. In the present invention, Ni-Zn based ferrite, Mg-Zn
At least one magnetic powder selected from the group consisting of a ferrite and a Cu ferrite and having a porosity of 5% or less is used. When a magnetic material powder having a large porosity is dispersed in a synthetic resin, it is difficult to obtain a resin composition having excellent withstand voltage. The porosity is preferably 4% or less, more preferably 3% or less, and further preferably 2% or less. By lowering the porosity of the magnetic powder, the withstand voltage of a molded product obtained from the resin composition can be generally 3000 V or higher, preferably 3500 V or higher, more preferably 5000 V or higher. Porosity of 1
% Or less, an excellent withstand voltage exceeding 5000 V can be obtained.

The mixing ratio of the magnetic powder is 100
300 to 2000 parts by weight, preferably 400 to 1500 parts by weight, more preferably 500 to 10 parts by weight with respect to parts by weight.
00 parts by weight. If the mixing ratio of the magnetic powder is too small, it is difficult to obtain a resin composition having sufficient magnetic permeability. If the mixing ratio is too large, the fluidity of the resin composition is reduced and molding becomes difficult. The average particle size of the magnetic powder is 10 μm
It is preferably at least 1 mm. If the average particle size of the magnetic powder is too small, it is difficult to obtain sufficient magnetic permeability, and the withstand voltage also decreases, such being undesirable. If the average particle size of the magnetic substance powder is too large, abrasion of the molding machine proceeds extremely and molding becomes difficult, which is not preferable.
The average particle size of the magnetic powder is preferably 15 to 750 μm.
m, more preferably 20 to 100 μm.

The synthetic resin used in the present invention includes, for example, polyolefins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ionomer; nylon 6, nylon 66, nylon 6/66, nylon 46, nylon 12, and the like. Polyamide; Polyarylene sulfide such as polyphenylene sulfide, polyphenylene sulfide ketone, polyphenylene sulfide sulfone; Polyester such as polyethylene terephthalate, polybutylene terephthalate, wholly aromatic polyester; Polyimide resin such as polyimide, polyether imide, polyamide imide; Polystyrene Resins such as styrene, acrylonitrile-styrene copolymer; polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer , Chlorine-containing vinyl resins such as chlorinated polyethylene; poly (meth) acrylates such as polymethyl acrylate and polymethyl methacrylate; acrylonitrile resins such as polyacrylonitrile and polymethacrylonitrile; tetrafluoroethylene / perfluoro Fluororesins such as alkyl vinyl ether copolymers, polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymers, polyvinylidene fluoride; silicone resins such as polydimethylsiloxane; polyphenylene oxide; polyether ether ketone; polyether ketone; Engineering plastics such as polyarylate, polysulfone, polyethersulfone; polyacetal, polycarbonate, polyvinyl acetate, polyvinyl Various thermoplastic resins such as lumar, polyvinyl butyral, polybutylene, polyisobutylene, polymethylpentene, butadiene resin, polyethylene oxide, oxybenzoyl polyester, and polyparaxylene resin; thermosetting resins such as epoxy resin, phenol resin and unsaturated polyester resin Resins; elastomers such as ethylene propylene rubber, polybutadiene rubber, styrene butadiene rubber, and chloroprene rubber; thermoplastic elastomers such as styrene-butadiene-styrene block copolymer; and mixtures of two or more of these. Among them, polyolefins such as polyethylene and polypropylene, polyamides, polyarylene sulfides such as polyphenylene sulfide, and epoxy resins are particularly preferable from the viewpoint of moldability.

The resin composition of the present invention may contain various fillers such as fibrous fillers and non-fibrous (plate, granular, powder, spherical) fillers in order to improve mechanical properties and heat resistance. Material can be included. In the resin composition of the present invention,
If necessary, various additives such as a flame retardant, an antioxidant, and a coloring agent can be blended. The resin composition of the present invention can be produced by uniformly mixing the components. For example, a resin composition can be produced by mixing predetermined amounts of the magnetic powder and the synthetic resin by a mixer such as a Henschel mixer and melt-kneading.
The resin composition of the present invention can be formed into a molded article having a desired shape by various molding methods such as injection molding, extrusion molding, and compression molding. The molded body thus obtained is
It has excellent magnetic permeability and withstand voltage, for example,
It can be applied to a wide range of applications such as coils, transformers, line filters, and electromagnetic wave shielding materials.

[0017]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to only these examples. The measuring methods of various physical properties are as follows. (1) Measurement method of withstand voltage A disc-shaped electrode is brought into contact with both sides of a 0.8 mm thick plate-shaped molded product, and cut off at a measurement temperature of 23 ° C. using a pressure tester TOS5050 manufactured by Kikusui Electronics Corporation. cut
off) The current was 1 mA, and the maximum AC voltage that could be applied for 60 seconds was determined. (2) Method of measuring magnetic permeability Measured according to JIS C2561. (3) Average particle diameter of magnetic substance powder Two cups of the powder sample were taken with a microspatula, placed in a beaker, and an anionic surfactant (SN Dispersat 54) was added.
After adding 1 to 2 drops of (68), the powder sample was kneaded with a rod having a rounded tip so as not to be crushed. Using this sample, the average particle diameter was measured with a Nikkiso Co., Ltd. Microtrac FRA particle size analyzer 9220 type. (4) Method of Measuring Porosity of Magnetic Powder A plate-shaped molded product having a thickness of 0.8 mm was polished until the cross section of the magnetic powder was visible. JEOL scanning electron microscope JSM
The cross section of the magnetic substance powder was observed using -630F. 1
The cross section of zero magnetic powder was observed, and the porosity inside the magnetic powder was calculated using an image processing apparatus JED-2100 manufactured by JEOL Ltd. based on the area.

Example 1 MgO (10.9% by weight),
ZnO (14.8% by weight), CuO (1.2% by weight),
MnO (3.2% by weight), CaO (0.16% by weight),
SiO ₂ (0.07% by weight), NiO (0.06% by weight), Bi ₂ O ₃ (0.3% by weight), PbO (0.01% by weight), Fe ₂ O ₃ (69.3% by weight) ) Was calcined at 1000 ° C., then pulverized, and then granulated using a spray dryer according to a conventional method. The obtained granules were fired at 1350 ° C. for about 3 hours, and cooled to room temperature over about 8 hours to obtain a sintered body of Mg—Zn ferrite. This sintered body is pulverized with a hammer mill and has an average particle diameter of 47 μm.
Was obtained. The specific gravity of the obtained powder was 4.6. Powder of the obtained Mg-Zn ferrite 17.2k
g, polyphenylene sulfide (Kureha Chemical Industry; 31
The melt viscosity at 0 ° C. and a shear rate of 1000 / sec is about 20.
2.8 kg (Pa · s) were weighed and mixed with a 20 L Hensyl mixer. Further, the obtained mixture is 280-33
The mixture is fed to a twin-screw extruder set at 0 ° C, melt-kneaded,
A pellet composition was obtained.

The obtained composition was supplied to an injection molding machine (JW / 75E manufactured by Nippon Steel Works), and the cylinder temperature was set to 280-3.
A 10 mm × 130 mm × 0.8 mm plate-shaped molded product was obtained at 10 ° C., an injection pressure of about 1000 kgf / cm ² , and a mold temperature of about 160 ° C. When the withstand voltage of the obtained molded product was measured, it was over 5000 V. The obtained plate-like molded product was polished, and the porosity in the magnetic material powder was measured with a scanning electron microscope. As a result, the porosity in the magnetic material was 1%. Further, the obtained composition was injected into an injection molding machine (PS-1 made by Nissei Resin).
0E), a cylinder temperature of 280 to 310 ° C., an injection pressure of about 1000 kgf / cm ² , and a mold temperature of about 160 ° C.
, A toroidal core was formed. When the magnetic permeability was measured using the obtained toroidal core, it was 17.5.

Example 2 A raw material mixture having the same composition as in Example 1 was fired at a temperature of 1250 ° C. for 3 hours and gradually cooled to room temperature over 8 hours to obtain a sintered body of Mg—Zn ferrite. Mg-Z was obtained from the obtained sintered body in the same manner as in Example 1.
An n-type ferrite powder was obtained. The average particle size of the obtained powder was 50 μm. Hereinafter, the same operation as in Example 1 was performed. Table 1 shows the obtained results.

Example 3 MgO (11.0% by weight),
ZnO (15.2% by weight), CuO (0.45% by weight), MnO (3.0% by weight), CaO (0.16% by weight), SiO ₂ (0.15% by weight), NiO (0. 2% by weight), WO ₃ (0.03% by weight), PbO (0.01% by weight)
Wt.) And Fe ₂ O ₃ (69.8 wt.%) Were calcined at 1000 ° C., pulverized, and then granulated using a spray dryer according to a conventional method. The obtained granules were fired at 1350 ° C. for about 3 hours and cooled to room temperature over about 8 hours to obtain a sintered body of Mg—Zn ferrite. This sintered body is pulverized with a hammer mill and has an average particle size of 4
A powder of 4 μm was obtained. Hereinafter, the same operation as in Example 1 was performed. Table 1 shows the results.

Comparative Example 1 A mixture having the same composition as in Example 1 was fired at a temperature of 1200 ° C. for 3 hours and gradually cooled to room temperature over 8 hours to obtain a Mg—Zn ferrite sintered body.
This sintered body is pulverized with a hammer mill and has an average particle diameter of 40 μm.
m were obtained. Hereinafter, the same operation as in Example 1 was performed. Table 1 shows the results.

Comparative Example 2 A mixture having the same composition as in Example 3 was fired at a temperature of 1250 ° C. for 3 hours and gradually cooled to room temperature over 8 hours to obtain a sintered body of Mg—Zn ferrite.
This sintered body is pulverized by a hammer mill and has an average particle diameter of 45 μm.
m were obtained. Hereinafter, the same operation as in Example 1 was performed. Table 1 shows the results.

[0024]

[Table 1]

[0025]

According to the manufacturing method of the present invention, Ni-Zn
By using at least one type of magnetic powder selected from the group consisting of ferrite, Mg—Zn ferrite, and Cu ferrite, and setting the porosity of the magnetic powder to 5% or less, an appropriate A resin composition having magnetic permeability and remarkably improved withstand voltage is provided. Therefore, the resin composition of the present invention can be suitably applied to molded articles requiring a high withstand voltage, such as coils, transformers, and line filters, by utilizing the properties of excellent magnetic permeability and withstand voltage.

Claims (4)

[Claims] 1. A resin composition containing a synthetic resin and a soft ferrite powder, wherein the soft ferrite powder is Ni
-Zn ferrite, Mg-Zn ferrite, and C
A resin composition comprising at least one magnetic powder selected from the group consisting of u-based ferrites and having a porosity of 5% or less. 2. The resin composition according to claim 1, which comprises 300 to 2,000 parts by weight of magnetic powder based on 100 parts by weight of the synthetic resin. 3. The resin composition according to claim 1, wherein the average particle size of the magnetic powder is 10 μm or more and 1 mm or less. 4. The resin composition according to claim 1, wherein the synthetic resin is a polyolefin, a polyamide, a polyphenylene sulfide, or an epoxy resin.