JP2876088B2 - Ferrite / resin composite composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention aims to provide a ferrite / resin composite composition having high magnetic permeability and excellent fluidity.

The main application of the ferrite / resin composite composition according to the present invention is a bonded magnetic material, and it is used as a core material for induction coils of various electronic devices such as computers, communication devices and consumer devices, a magnetic core material for transformers, and a magnetic material for electromagnetic shielding. Used for sheets and the like.

[Conventional technology]

As is well known, bond magnetic materials are smaller, thinner, and more compact than sintered magnetic materials because of their superior dimensional accuracy, workability, and fragility.
There is an advantage that even a product having a complicated shape can be easily mass-produced. In recent years, with the development of electronics, demands for weight reduction, downsizing and precision making use of these advantages have been further strengthened.

In general, a bonded magnetic material is manufactured by kneading a magnetic material powder and a resin such as nylon or phenol, and then compressing or injection molding to obtain a molded body.

As the magnetic material powder, Mn-Zn ferrite, Ni
Oxide-based materials such as Zn-based ferrite are used, and usually the main raw materials, such as Fe ₂ O ₃ , MnO, ZnO, and NiO, are mixed and mixed in advance in a wet or dry manner so as to have a desired composition. ,
It is obtained by a method in which granulation is carried out after granulating to a diameter of about several mm to several tens of mm, followed by baking, and then pulverization to a size of about several μm to several hundred μm.

It is required that the magnetic permeability of the bond magnetic material be as large as possible, and recently, with the demand for higher performance of the bond magnetic material, the demand has been increasing.

By the way, recently, as the performance of the bonded magnetic material has been improved, the demand for a compact, thinned, and complicated shaped product has been increasingly increased. In order to satisfy this requirement, it is important that the ferrite-resin composite composition be easily filled over the details of the mold, and for that purpose, the fluidity of the ferrite-resin composite composition is required. It is required to be excellent.

[Problems to be solved by the invention]

Ferrite-resin composite compositions having high magnetic permeability and excellent fluidity are currently the most demanded, but Mn-Zn ferrite and Ni-Zn ferrite particles according to the above-mentioned conventional methods. Ferrite-resin composite compositions obtained using powders have not yet sufficiently satisfied these properties. This fact will be described below.

The magnetic permeability and fluidity of the ferrite / resin composite composition
It mainly depends on the characteristics of the ferrite particle powder blended in the resin composition constituent base material. That is, the magnetic permeability of the ferrite-resin composite composition tends to increase as the magnetic permeability of the ferrite particles to be compounded increases, and the fluidity of the ferrite-resin composite composition is determined by the flow rate of the ferrite particles to be compounded. The smaller the average particle diameter and the smoother the surface of the particles, the better. The magnetic permeability of the ferrite particle powder is closely related to the average particle diameter, and as the average particle diameter increases, the magnetic permeability increases, and thus the magnetic permeability of the ferrite-resin composite composition also increases. When the average particle diameter of the particle powder increases, the fluidity of the ferrite / resin composite composition tends to deteriorate.

Ferrite particle powder obtained by the conventional method,
Due to the manufacturing method, the crystal grains grew hugely to several hundred μm and became non-uniform.Moreover, the crystal grains contained many vacancies. The presence of the vacancies reduced the magnetic permeability, and as a result, only particles having a small magnetic permeability were obtained. Further, since the shape of the particles becomes angular particles by pulverization, ferrite particles having excellent fluidity have not been obtained. By the way, looking at the relationship between the magnetic permeability and the average particle diameter of the ferrite particle powder obtained by the conventional method, generally when the average particle diameter is about 100 μm, the magnetic permeability is about 18 and the average particle diameter is 200
In the case of about μm, the magnetic permeability is about 23.

Therefore, in order to obtain a ferrite-resin composite composition having a high magnetic permeability and excellent fluidity, a ferrite particle powder to be compounded has a large magnetic permeability and an appropriate degree that does not hinder the fluidity. Average particle size of the size, especially 20
It is required that the surface is as small as 0 μm or less and the surface is as smooth as possible.

Therefore, the present invention provides ferrite particles having a high magnetic permeability and excellent fluidity, because the ferrite particle powder to be compounded has a large magnetic permeability, has an appropriate size, and is as smooth as possible. -To obtain a resin composite composition as a technical subject.

[Means for solving the problem]

The technical problem can be achieved by the present invention as described below.

That is, the present invention provides a ferrite / manganese / zinc ferrite spherical particle powder having an average particle diameter of 20 to 150 μm, which is formed by crystal grains having an average particle diameter of 5 to 15 μm, which is blended in a resin composition constituent base material. A resin composite composition,
The ferrite / resin composite composition has a magnetic permeability of 25 or more and has excellent fluidity.

Next, various conditions for implementing the present invention will be described.

In the present invention, manganese having an average particle diameter of 20 to 150 μm, which is formed by crystal grains having an average particle diameter of 5 to 15 μm.
Zinc ferrite spherical particle powder is 4 when converted to Fe ₂ O ₃
7 to 58 mol% of iron oxide or hydrated iron oxide powder and MnO
Manganese oxide in an amount of 22 to 30 mol% when converted to
With one or more powders of manganese compounds selected from manganese dioxide, manganese trioxide and manganese carbonate
A ferrite-forming mixed powder comprising zinc oxide powder in an amount of 15 to 32 mol% in terms of ZnO is added to water containing 0.2 to 1.0% by weight of a surfactant based on the weight of the ferrite forming mixed powder. Dispersed and mixed in a slurry concentration of 40-60
After preparing a water-dispersed slurry by weight and spray-drying to obtain spherical granules having an average particle diameter of 25 to 180 μm, the granules are fired in a temperature range of 1150 to 1350 ° C. in nitrogen gas. Obtained by

Ferrite particles used in the present invention, Fe ₂ O ₃ 47~58
It consists of ferrite particles having a composition expressed by mol%, MnO22 to 30 mol%, and ZnO15 to 32 mol%. Ferrite particles having a composition in this range can be used as a ferrite material for a bonded magnetic material. In this case, the magnetic permeability becomes low, which is not preferable for practical use.

As an iron oxide powder which is one of the starting materials, α-Fe ₂ O
₃ , γ-Fe ₂ O ₃ or Fe ₃ O ₄ etc., and as the iron oxide hydroxide powder, α-FeOOH, β-FeOOH, γ-FeOOH or the like can be used. Most preferred is α-Fe ₂ O ₃ .

The ferrite particle powder in the present invention has an average particle size of 5
Average particle size of 20 formed by crystal grains of ~ 15 μm
It must be a manganese-zinc ferrite spherical particle powder of ~ 150 µm. If it is less than 20 μm, the particle growth becomes insufficient, which is not preferable. If it exceeds 150 μm, crystal grains grow abnormally, and vacancies tend to remain, leading to a decrease in magnetic permeability, which is not preferable.

In order to obtain the above-mentioned ferrite particle powder in the present invention, it is necessary to control the average particle diameter of the granulated product before firing in the range of 25 to 180 μm.

For this purpose, the mixed powder for ferrite formation should be 0.2-1.0
% By weight (based on the weight of the mixed powder for ferrite formation) in water containing a surfactant.
After preparing a 40-60% by weight aqueous dispersion slurry, the slurry must be spray dried. When the slurry concentration is less than 40% by weight, the spray drying efficiency is deteriorated and the productivity is reduced. When the slurry concentration is more than 60% by weight, supply becomes difficult and spray drying becomes impossible.

As the surfactant, an alkali metal salt of an anionic surfactant usually used as a dispersant for an aqueous dispersion slurry,
Amine salts, ammonium salts or lower fatty acid salts of cationic surfactants, hydrochlorides, etc. can be used, and the amount used is 0.2 to the weight of the ferrite-forming mixed powder in consideration of the spherical shape of the obtained ferrite particle powder. ~ 1.0% by weight is preferred.

Firing is performed in a temperature range of 1150 to 1350 ° C. in nitrogen gas. 11
When the temperature is lower than 50 ° C., ferrite is insufficiently generated and a crystal having a large crystal grain cannot be obtained. If the temperature exceeds 1350 ° C,
It is not preferable because abnormal growth of crystal grains is promoted, and nonuniform and many vacancies are generated.

The manganese-zinc ferrite spherical particle powder in the present invention is a silane coupling agent, a titanium coupling agent, an aluminum-based coupling agent, and a zirco-aluminate-based agent, which are usually used as surface treatment agents for improving various properties such as dispersibility. It may be coated in advance with a coupling agent such as a coupling agent or a surfactant such as a cationic, anionic or nonionic surfactant.

The mixing ratio of the manganese / zinc ferrite spherical particle powder in the present invention can be used in the range of 90 to 95 parts by weight with respect to 5 to 10 parts by weight of the resin composition constituting base material. Considering magnetic susceptibility and fluidity,
92 to 94 parts by weight is preferable based on 6 to 8 parts by weight of the resin composition constituting base material.

The resin composition constituting base material of the present invention contains a resin and, if necessary, a plasticizer, a lubricant, an antioxidant, and the like.

As the resin, thermoplastic resins such as polystyrene resin, polyethylene resin, AS resin, ABS resin, vinyl chloride resin, EVA resin, PMMA resin, polyamide resin, polypropylene resin EEA resin and PPS resin which are usually used for resin compositions , Phenolic resin, urea resin, melamine resin,
Thermosetting resins such as alkyd resins, epoxy resins, and polyurethane resins can be used.

The ferrite-resin composite composition according to the present invention can be used in any method such as a compression molding method and an injection molding method.
Since it has excellent fluidity, it is particularly preferably used for injection molding.

[Action]

First, the most important point in the present invention is that the average particle size is 5%.
Average particle size of 20 formed by crystal grains of ~ 15 μm
Ferrite / resin composite composition in which manganese / zinc ferrite spherical particle powder of ~ 150 μm is blended in the resin composition constituent base material has a large magnetic permeability of the manganese / zinc ferrite spherical particle powder blended. Due to this fact, the magnetic permeability is as large as 25 or more.

Since the manganese-zinc ferrite spherical particle powder in the present invention is a particle having an appropriate size and a spherical surface having a smooth surface, a ferrite-resin composite containing the manganese-zinc ferrite spherical particle powder is blended. The composition is
It has excellent fluidity.

Regarding the reason why the magnetic permeability of the manganese / zinc ferrite spherical particle powder blended in the present invention is large, the present inventor has found that the crystal grains are uniform and have an appropriate size, and the presence of pores is small. I believe it is due to

〔Example〕

 Next, the present invention will be described with reference to Examples and Comparative Examples.

The magnetic permeability of the ferrite particle powder in the following Examples and Comparative Examples was obtained by granulating a mixture of 20 parts by weight of ferrite particle powder and 1 part by weight of an aqueous polyvinyl alcohol solution.
Using 1 ton / at a pressure of cm ² the outer diameter 36Mmfai × inner diameter 24 mm × green compact obtained by press molding the cylindrical height of 10mm as a sample, In addition, the magnetic permeability of the ferrite resin composite composition, the powder A molded body composed of a ferrite resin composite composition having the same size as the molded body was used as a measurement sample, and each measurement sample was wound 40 times with a winding (0.25 mmφ) and an impedance analyzer 4194A (Yokogawa / Hewlett / This is a value measured under the condition of a frequency of 1 MHz using Packard Co., Ltd.).

<Production of Manganese Zinc Ferrite Particle Powder> Examples 1 to 6 Comparative Examples 1 to 7; Example 1 41.92 kg of iron oxide (α-Fe ₂ O ₃ ) and 11.44 kg of manganese oxide
And 8.63 kg of zinc oxide, and Fe ₂ O ₃ : 52.4 mol%, Mn
A ferrite-forming mixed powder having a composition of O: 26.4 mol% and ZnO: 21.2 mol% was prepared. Then, the mixture was treated with ammonium polycarboxylate (SN Dispersant 5468).
0.3% by weight (manufactured by San Nopco Co., Ltd.) (based on the weight of the mixed powder for forming ferrite) was dissolved in 60 l of an aqueous solution. The slurry concentration in the aqueous solution was 50.8% by weight. Subsequently, the slurry is spray-dried to give an average particle size of 110 μm.
m was obtained.

The obtained granules were fired at a temperature of 1340 ° C. for 3 hours to form ferrite, thereby obtaining ferrite particles for a bonded magnetic material comprising manganese / zinc ferrite spherical particles.

The magnetic permeability of the obtained ferrite particle powder for a bond magnetic material was 32.5, and as a result of observation with a scanning electron microscope photograph shown in FIG. 1, the average particle diameter formed by crystal grains having an average particle diameter of 14.8 μm was obtained. It was a manganese / zinc ferrite spherical particle of 94 μm, and it was confirmed that the particle had few pores.

Examples 2 to 6, Comparative Examples 1 to 7 Except that the composition ratio of the mixed powder for ferrite formation, the type and amount of the surfactant, the concentration of the mixed slurry for ferrite formation, the size of the granulated material, and the firing temperature were variously changed. In the same manner as in Example 1, ferrite particle powder was obtained.

Table 1 shows the main production conditions and the characteristics of the ferrite particles at this time.

The iron oxide raw material in Example 3 was Fe ₃ O ₄ , the manganese raw material in Example 4 was manganese trioxide, and the surfactant in Example 5 was sodium polycarboxylate (Nopcosanto K). San Nopco) was used.

In Comparative Example 7, a granulated material of about 5 mm was prepared by a conventional method without spray-drying the ferrite-forming mixed powder, and the granulated product was fired in a temperature range of 1300 ° C., and then the fired product was pulverized. As a result, ferrite particle powder having an average particle diameter of 46.0 μm and having many pores was obtained.

<Production of Ferrite / Resin Composite Composition> Examples 7 to 11 Comparative Examples 8 to 11; Example 7 190 g of ferrite particle powder obtained in Example 1 (corresponding to 95 parts by weight based on the composition), ethylene -Vinyl acetate copolymer resin Evaflex 250 (density 0.95g / cc)
10 g (corresponding to 5.0 parts by weight of the composition) and 0.2 g of zinc stearate (corresponding to 0.1 part by weight of the composition) of Plastmill 30C- (manufactured by Mitsui Polychemicals, Inc.)
Using a 150 (manufactured by Toyo Seiki Co., Ltd.), the mixture was kneaded at a temperature of 110 ° C. for 15 minutes to obtain a kneaded product.

After granulating the obtained kneaded material to form a granulated product having an average particle size of about 3 mm, under a pressure of 1.5 ton / cm ² , press-molding was performed at a temperature of 75 ° C., and an outer diameter of 36 mmφ × an inner diameter of 24 mmφ × a height of 10 mm Was obtained. The molded article has a smooth surface as a result of the ferrite resin composition being sufficiently filled to the corner details,
In addition, the circumferential portions of the upper and lower surfaces of the cylindrical shape also formed complete circles, and there was no missing or deformation.

 The magnetic permeability of this molded product was 30.6.

Examples 8 to 11, Comparative Examples 8 to 11 Same as Example 7 except that the type and amount of ferrite particle powder, the type and amount of resin, the type and amount of additive, and the kneading temperature and time were variously changed. Thus, a ferrite / resin composite composition was obtained.

 Table 2 shows the main manufacturing conditions and characteristics at this time.

As in the case of the ferrite-resin composition obtained in Example 7, the ferrite-resin composition obtained by using the ferrite-resin composition obtained in Examples 8 to 11 had As a result of sufficient filling of the details, the surface was smooth, and the circumferences of the cylindrical upper and lower surfaces also formed complete circles, and were not missing or deformed.

The molded body manufactured using the ferrite-resin composition obtained in Comparative Example 8 and Comparative Example 11 has irregularities on the surface,
In addition, a part of the circumference of the upper surface and the lower surface of the cylindrical shape was missing or deformed.

[Effects of the Invention] The ferrite-resin composite composition according to the present invention is, as described in the preceding examples, due to the large magnetic permeability of the ferrite particle powder blended in the resin composite constituting base material. Thus, the magnetic permeability is large, especially 25 or more, and the ferrite particle powder has an appropriate size, and has excellent fluidity due to its surface having a smooth spherical shape. Therefore, it is suitable as a ferrite / resin composition currently required.

Since the ferrite / resin composite composition according to the present invention has a large magnetic permeability, it is expected to be used as an electromagnetic wave absorbing material and an electromagnetic wave shielding material.

[Brief description of the drawings]

1 to 6 are scanning electron microscope photographs (× 65
0), FIG. 1 is Example 1, FIG. 2 is Example 2 and FIG. 3 is a scanning electron micrograph showing the particle structure of the ferrite particle powder obtained in Example 4, and FIG. 3, Figure 5
FIG. 6 is a scanning electron micrograph showing the particle structure of the ferrite particle powder obtained in Comparative Example 7, and FIG.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C08K 3/00-3/40 C08K 7/00-7/28 H01F 1 / 113,1 / 37

Claims (1)

(57) [Claims] 1. A ferrite / resin in which a manganese / zinc ferrite spherical particle powder having an average particle diameter of 20 to 150 μm formed by crystal grains having an average particle diameter of 5 to 15 μm is blended in a resin composition constituting base material. A ferrite / resin composite, wherein the ferrite / resin composite composition has a magnetic permeability of 25 or more, and has excellent fluidity.
Resin composite composition.