JPH0699588B2 - Ferrite-containing plastic composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferrite-containing plastic composition for molding a noise suppression component used for noise suppression of various electronic devices.

[Conventional technology]

FIG. 2 is a perspective view of a conventional ferrite bead for removing high frequency noise. In the figure, 4 is a ferrite bead molded with a ferrite-containing plastic composition, 2 is a through hole, and 3 is a lead wire passing through the through hole 2.

In this configuration, the ferrite bead 4 portion has an impedance in a high frequency region and has an action of absorbing and attenuating high frequency noise mixed in a signal transmitted through the lead wire 3.

[Problems to be Solved by the Invention]

The above-mentioned conventional ferrite beads formed from a ferrite-containing plastic molded product have a small ferrite particle content and a low ferrite content, so they have a small effect of absorbing and attenuating high-frequency noise, resulting in an effective attenuation effect. I can't get it. The shape must be increased to increase the damping effect.

Further, if the particle size of ferrite particles is made too large in order to enhance the damping effect, the moldability and workability characteristic of plastic ferrite are lost.

The present invention has been made to solve the above-mentioned problems, and can effectively remove high-frequency noise, and also have moldability and workability which are characteristics of plastic ferrite (containing plastic composition). It is an object to provide a ferrite-containing plastic composition.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is to appropriately select the range and distribution of the grain size of the contained ferrite.
The ferrite-containing plastic composition is
Configure as in (2).

(1) A ferrite-containing plastic composition containing soft ferrite powder, plastic, and a small amount of additives, wherein the soft ferrite powder is a single or mixed ferrite powder having an average particle size of 100 to 500 μm. A ferrite-containing plastic composition having a soft ferrite content of 80% by weight or more based on the whole.

(2) A ferrite-containing plastic composition containing soft ferrite powder, plastic, and a small amount of additives, wherein the soft ferrite powder has an average particle size of 100 μm to 2 μm.
A ferrite-containing plastic composition comprising main large-sized particles having a content of 50% by weight or more based on the entire soft ferrite in mm, and several small-sized particles filling gaps between the large-sized particles.

[Operation] With the configurations of (1) and (2), magnetic characteristics close to those of a sintered ferrite body can be obtained, the packing density can be increased, and formability and workability as a plastic ferrite can be maintained. .

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 is a perspective view of ferrite beads for removing high frequency noise, which are molded from the “ferrite-containing plastic composition” of the first embodiment of the present invention.

In the figure, 1 is a molded product (ferrite bead) having an outer diameter of 10 mm and a thickness of 3 mm molded from the ferrite-containing plastic composition of the present embodiment, and a through hole 2 having a diameter of 0.5 mm is opened in the center thereof. There is. A lead conductor 3 having a diameter of 0.3 mm is passed through the through hole 2. The end portion of the lead wire 3 was connected to a measuring instrument, and the magnetic permeability and the attenuation characteristic of the molded body in the high frequency region were measured to obtain the characteristics shown in Table 1 below.

Next, how to make this molded body will be described.

A calcined body of soft ferrite of nickel-zinc system was pulverized, a small amount of PVA (polyvinyl alcohol) aqueous solution was added to prepare granules, and the granules were fired to obtain sintered ferrite particles. This was classified to obtain ferrite powders having different particle diameters. Taking into consideration the particle size and content of this ferrite powder, weigh the ferrite powder and the binder plastic, select an appropriate solvent, dissolve the weighing plastic, stir and mix the weighed ferrite powder, and then The solvent was evaporated to give a soft ferrite powder coated with plastic. This was molded by a dry powder pressing method to form a molded body having an outer diameter of 10 mm and a thickness of 3 mm. In this central part
A hole having a diameter of 0.5 mm was opened to obtain a test molded body.

Next, as shown in FIG. 1, the lead wire 3 was passed through, and the magnetic permeability and the damping characteristic of the molded body were measured. The main measurement results are shown in Table 1 below.

As shown in Table 1, the particle size of soft ferrite is 500 μm
It is found that when the value exceeds 1.0, the formability and workability deteriorate, the characteristics as plastic ferrite are lost, and when the particle size is less than 100 μm, the magnetic permeability and the attenuation amount deteriorate.

Next, the "ferrite-containing plastic composition" of the second embodiment of the present invention containing the soft ferrite powder composed of large-sized particles and several kinds of small-sized particles filling the gaps between them will be described.

Ferrite beads similar to those shown in FIG. 1 were molded from the composition of this example, and the magnetic permeability and attenuation characteristics in the frequency region were measured, and the characteristics shown in Table 2 below were obtained.

The method of forming the molded body is the same as that of the first embodiment except that the particle size of the soft ferrite powder is selected.

Table 2 below shows the main results of the measurement of the molded body through the lead wire.

As shown in Table 2, in the soft ferrite particle size distribution, the main particle having the maximum particle size is about 100 μm or more, which accounts for about 50% by weight or more in the total ferrite,
Moreover, it can be seen that when the total ferrite content in the composition accounts for 80% by weight or more, the magnetic permeability and the attenuation amount of the molded body increase.

In addition, the formability and workability of the plastic ferrite are not lost.

The plastics used in the present invention include thermoplastic nylon, PE (polyethylene), PP (polypropylene), PS (polystyrene), acrylic resin, polyester resin, etc., and thermosetting epoxy resin, phenol resin, etc. Wide choice. Also, as additives used,
There are coupling agents that improve the bond between ferrite powder and plastics, mold release agents that improve mold release, and lubricants. The forming density is improved by making the shape of the soft ferrite particles spherical. As the molding method, various molding methods such as injection molding, extrusion molding and transfer molding can be used in addition to the above-mentioned powder pressing method.

Although the example of ferrite beads has been described as an application example, other applications include housings that utilize the electromagnetic shield effect, choke coils for noise filters, and other applications of nonmagnetic resin in ferrite application parts such as transformers. Thus, high efficiency can be achieved by molding with a molded product molded from the composition of the present invention.

〔The invention's effect〕

As described above, according to the present invention, in the ferrite-containing plastic composition, by controlling the range of the average particle size of the soft ferrite particles, the distribution and the ferrite content, the formability as plastic ferrite,
It is possible to obtain a ferrite-containing plastic composition having magnetic properties capable of effectively removing high frequency noise while maintaining processability.

[Brief description of drawings]

FIG. 1 is a perspective view of ferrite beads molded from the composition of the first embodiment of the present invention, and FIG. 2 is a perspective view of conventional ferrite beads. In the figure, 1 and 4 are ferrite-containing plastic moldings. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A ferrite-containing plastic composition comprising soft ferrite powder, plastic, and a small amount of additives, wherein the soft ferrite powder has an average particle size of 100 to 500 μm.
A ferrite-containing plastic composition which is a single or mixed ferrite powder of m and has a soft ferrite content of 80% by weight or more based on the entire composition. 2. A ferrite-containing plastic composition comprising soft ferrite powder, plastic and a small amount of additives, wherein the soft ferrite powder has an average particle size of 100 μm.
A ferrite-containing plastic characterized by comprising main large-sized particles having a content of m to 2 mm with respect to the whole soft ferrite of 50% by weight or more, and several kinds of small-sized particles filling gaps of the large-sized particles. Composition.