JPH0364005A - Plastic composition containing ferrite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferrite-containing plastic composition for molding noise countermeasure parts used for noise countermeasures in various electronic devices.

[Conventional technology]

FIG. 2 is a perspective view of a conventional ferrite bead for removing high-frequency noise. In FIG. 0, 4 is a ferrite bead molded from 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 impedance in a high frequency region and has the function of absorbing and attenuating high frequency noise mixed into the signal transmitted through the lead wire 3.

[The problem that the invention attempts to solve]

Conventional ferrite beads such as those described above, which are made of ferrite-containing plastic molded bodies, have small ferrite particles and a low ferrite content, so they have little absorption and attenuation of high-frequency noise and do not have an effective attenuation effect. To increase the damping effect, the shape must be made larger.

Furthermore, if the particle size of the ferrite particles is made too large in order to increase the damping effect, the moldability and processability, which are characteristics of plastic ferrite, are lost.

The present invention was made in order to solve the above-mentioned problems, and can effectively remove high-frequency noise, as well as provide moldability and processability that are characteristic of plastic ferrite (plastic compositions containing it). An object of the present invention is to provide a ferrite-containing plastic composition.

(Means for Solving the Problems) In order to achieve the above object, the present invention appropriately selects a range 1 distribution of grain sizes of the contained ferrite.
The ferrite-containing plastic composition is prepared as follows (1), (
Configure as in 2).

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

(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
A ferrite-containing plastic composition comprising main large particles having a diameter of 2 mm and a content of 50% by weight or more based on the total soft ferrite, and several types of small particles filling the gaps between the large particles.

(Function) With the configurations (1) and (2) above, magnetic properties close to those of sintered ferrite bodies can be obtained, the packing density can be increased, and the moldability and processability of plastic ferrite can be obtained. I can do it.

(Example) The present invention will be explained in detail below based on examples.

FIG. 1 is a perspective view of a ferrite bead for removing high frequency noise, molded from a "ferrite-containing plastic composition" according to a first embodiment of the present invention.

In the figure, l is molded from the ferrite-containing plastic composition of this example, with an outer diameter of 10 m and a thickness of 3 mm.
The molded body is a ferrite bead) with 0 in the center.
A through hole 2 with a diameter of 650 mm is drilled. The through hole 2 has a 0.
A lead conductor 3 with a diameter of 3 mm is passed through it. This lead wire 3
The end of the molded body was connected to a measuring device to measure the magnetic permeability and attenuation characteristics of the molded body in a high frequency region, and the characteristics shown in Table 1 below were obtained.

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

A calcined body of nickel-zinc soft ferrite was crushed, a small amount of PVA (polyvinyl alcohol) aqueous solution was added to create granules, and the granules were fired to obtain *crystallized ferrite particles. This was classified to obtain ferrite powder with varying particle sizes. Considering the particle size and content of this ferrite powder, weigh the ferrite powder and binder plastic, select an appropriate solvent, and dissolve the weighed plastic.
The weighed ferrite powder was stirred and mixed, and then the solvent was evaporated to obtain a plastic-coated or ferrite powder. This was molded by a dry powder press method to produce a molded body with an outer diameter of 10 mm and a thickness of 3 mm. A hole with a diameter of 0.5 mm was made in the center to obtain a test molded product.

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

As shown in Group 1, the grain size of soft ferrite is 500μ
If it exceeds m, the moldability and processability will deteriorate, the characteristics as plastic ferrite will be lost, and the particle size will be 100 μm.
It can be seen that the smaller the value, the worse the magnetic permeability and attenuation.

Next, a "ferrite-containing plastic composition" according to a second embodiment of the present invention, which contains soft ferrite powder consisting of large-sized particles and several types of small-sized particles that fill 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 their magnetic permeability and attenuation characteristics in the high frequency region were measured to obtain the characteristics shown in Table 2 below.

The method for making the molded body is the same as in the first embodiment, except for the selection of the particle size of the soft ferrite powder.

The main results of measurements of the molded product passed through the lead wire are shown in Cloth 2 below.

As shown in Table 2, in the soft ferrite particle size distribution, the main maximum particle size is about 100 μm or more,
It can be seen that when this ferrite occupies about 50% by weight or more in the total ferrite, and the total ferrite content in the composition occupies 80% by weight or more, the magnetic permeability and attenuation of the molded article become large.

Moreover, the moldability and processability of plastic ferrite are not lost.

In addition, the plastics used in the present invention include thermoplastic nylon, PE (polyethylene), PP (polypropylene), PS (polystyrene), acrylic resin,
A wide range of materials can be selected from polyester resins, thermosetting epoxy resins, phenolic resins, etc. In addition, additives used include a coupling agent that improves the bond between the ferrite powder and the plastic, a mold release agent that improves the release from the mold, and a lubricant. By making the shape of the soft ferrite particles spherical, the molding density is improved. As the molding method, various molding methods such as injection molding, extrusion molding, and transfer molding can be used in addition to the powder pressing method described above.

We have explained the example of ferrite beads as an application example, but other applications include housings that utilize electromagnetic shielding effects, choke coils for noise filters, and non-magnetic resin usage fields in ferrite application parts such as transformers. Therefore, high efficiency can be achieved by molding a molded article made from the composition of the present invention.

(Effects of the Invention) As explained above, according to the present invention, in a ferrite-containing plastic composition, by controlling the range9 distribution of the average particle size of soft ferrite particles and the ferrite content, molding as plastic ferrite is possible. sex,
A ferrite-containing plastic composition can be obtained that has magnetic properties that can effectively remove high-frequency noise while maintaining processability.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a ferrite bead molded from the composition of Example 1 of the present invention, and FIG. 2 is a perspective view of a conventional ferrite bead. In the figure, 1.4 is a ferrite-containing plastic molded body. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A ferrite-containing plastic composition containing soft ferrite powder, plastic, and a small amount of additive, wherein the soft ferrite powder has an average particle size of 100 to 500 μm.
1. A ferrite-containing plastic composition, characterized in that the soft ferrite content is 80% by weight or more based on the entire composition. (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
A ferrite-containing plastic composition comprising main large-sized particles with a diameter of 2 mm and a content of 50% by weight or more based on the total soft ferrite, and several types of small-sized particles that fill the gaps between the large-sized particles. .