JPS582444B2 - Jishinzairiyoyousobutsu - Google Patents

Description

[Detailed description of the invention] The present invention relates to compositions for magnetic core materials.

More specifically, liquid rubber contains ZnO-Fe203 and general formula MO-Fe203 (M is Mn, Fe, Ni, Cu or M
a solid solution with ferrite represented by
The present invention relates to a composition for a magnetic core material having excellent moldability and processability, which contains a soft magnetic ferrite powder.

Soft magnetic ferrite has developed rapidly after the war, and has become an indispensable material, especially in the field of electronic technology.

Its characteristics are 1) high magnetic permeability, 11) high electrical resistivity, and II1) low cost.

However, since these ferrites are currently molded by sintering powder, 1) the yield and dimensional stability during molding are poor, 11) it is difficult to obtain molded products with complex shapes, and in some cases, iii) The surface oxidation during sintering is significant, so it has disadvantages such as being unsuitable for small-sized products.

An object of the present invention is to provide a soft magnetic ferrite composition that can be molded into complex shapes with good dimensional stability under mild conditions without sintering.

One of the reasons why soft magnetic ferrite is prized is that it has a high electrical resistivity (10 to 106 Ω cm), but liquid comb (1016 to 10
The electrical insulation properties are further improved by matrixing 17Ω-Cm).

The liquid rubber used in the present invention includes liquid polybutadiene, liquid polyisobrene, liquid polyisobutylene, and liquid copolymers thereof, as well as those into which hydroxyl groups, carboxyl groups, maleic anhydride groups, or isocyanate groups are introduced. A wide range of derivatives can be used.

Depending on the viscosity of the liquid rubber used, the composition of the present invention has
Its formability is affected.

For example, in rubbers with excessively low viscosity, in other words with low molecular weight, the chain length is too short for the liquid rubber to serve as a binder or matrix for the ferrite.

On the other hand, if the molecular weight is excessively high, the viscosity of the composition becomes too high, making it difficult to mold it using normal molding means.

Therefore, it goes without saying that the liquid rubber used must have an appropriate molecular weight based on preliminary experiments, depending on the type of ferrite or the molding method used.

For example, in the case of liquid polybutadiene rubber, those having an average molecular weight of 1,000 to 10,000 are preferably used.

The higher the mixing ratio of ferrite to liquid rubber, the more desirable it is from the viewpoint of magnetic properties.

For example, when liquid polybutadiene is used as the liquid rubber, a magnet composition having practical magnetic properties cannot be obtained if the mixing ratio is less than 1:1 by weight.

If the mixing ratio exceeds 10 times by weight, the viscosity of the composition becomes too high, resulting in poor flow during molding and poor moldability and processability.

The ferrite powder and liquid polybutadiene can be mixed in a conventional manner.

Next, the kneaded composition is processed using an injection molding machine, an extrusion molding machine,
By supplying to compression molding machines and calendar molding machines,
Can be molded into any shape.

The composition according to the present invention can be easily cured by adding a crosslinking agent or a vulcanizing agent during kneading.

The cured composition thus obtained has a rigidity of 1010 dynecm2) even at 300°C, and can withstand continuous use at 120°C, which is normally required when used in electrical parts, etc. I can do it.

The composition obtained according to the present invention can be widely used in fields where sintered ferrite has conventionally been used.

Specific examples include horizontal output flyback transformers for televisions, cores for deflection coils, and antenna coils for radios.

The present invention will be explained below with reference to Examples, but these Examples are not intended to limit the present invention in any way.

Examples 1 to 5 Liquid polybutadiene with an average molecular weight of 4000 (manufactured by Nippon Soda Co., Ltd., butadiene homopolymer, NISSOPB-400
0), a predetermined weight of manganese-zinc ferrite, and liquid polybutadiene, by kneading 2% dicumyl peroxide at room temperature using a colander, then extruding it into a rod shape with an extruder and cutting it. Diameter 2mm, length 5
A cylindrical chip with a diameter of mm was produced.

The chips were injection molded under the conditions of cylinder temperature 50°C, mold tolerance 20°C, and injection pressure 500 kg/cm2.
A plate-shaped test piece having a width of 50 mm and a thickness of 3 mm was obtained.

The moldability was good. A cured composition was obtained by heating the test piece at 150° C. for 3 hours.

Table 1 shows the magnetic properties of the obtained cured composition.

Examples 6-10 Instead of the liquid polybutadiene used in Examples 1-5,
Liquid polybutadiene with a molecular weight of 3000 into which terminal hydroxyl groups have been introduced (manufactured by Nippon Tsumatatsu Co., Ltd., hydroxyl group-introduced polybutadiene, N
Example 1 except that ISSO PSG-3000) was used.
A cured composition was obtained in exactly the same manner as in Example 5.

Their magnetic properties are shown in Table 2. Example 11 The following mixture was kneaded at room temperature using a mill.

Liquid polybutadiene with an average molecular weight of 6200 (Nippon Zeon Polyol 160) 12g manganese/zinc ferrite 120g sulfur
0.96g active zinc white
0.60g stearic acid
0.12g power sulfur accelerator (Mexela DM)
O. 12g vulcanization accelerator (Mexela H)
0.04g anti-aging agent (Nokrac NS#6) 0
．． 12g of the kneaded product was then molded in exactly the same manner as in Examples 1 to 5 to obtain a cured composition.

The Bm of the obtained molded product was 4062G.

Claims (1)

[Claims] 1 In liquid rubber, ZnO-Fe203 and general formula MO-F
A composition for a magnetic core material having excellent moldability and processability, characterized in that it contains soft magnetic ferrite powder which is a solid solution with ferrite represented by e203 (M is MnyFe, Ni, Cu or Mg).