JP2002198239A - Method of manufacturing magnetic body, the magnetic body, and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method, by which a soft flexible magnetic body having improved electromagnetic wave shielding ability, can be manufactured. SOLUTION: In this method, the soft flexible magnetic body 1 is manufactured through molding of a raw material prepared, by kneading soft magnetic powder in a macromolecular material. At molding of the raw material, the soft magnetic powder contained in the material is oriented in a prescribed direction B, by impressing a magnetic field A upon the material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a magnetic material having flexibility and flexibility by kneading a soft magnetic powder with a polymer material, a magnetic material produced according to the production method, and The present invention relates to a cable using the magnetic material as a coating.

[0002]

2. Description of the Related Art Conventionally, as a magnetic material having flexibility and flexibility, a magnetic material produced by kneading a soft magnetic material powder such as a ferrite powder with a polymer material such as rubber or plastic and molding the same is conventionally used. Are known. This magnetic material has a high degree of freedom in processing, and is used as a cover for this electronic device, for example, in the form of a sheet to reduce the leakage of electromagnetic waves generated by the electronic device and the effect of external noise on the electronic device. Is done. For the same purpose, a signal cable or a power cable for conducting electric signals (hereinafter collectively referred to as
In some cases, it is processed and used as a coating for a “cable”.

[0003]

However, the conventional magnetic material has the following problems. That is, in the conventional magnetic material, the soft magnetic material powder is merely kneaded and molded into a polymer material, and the direction of the soft magnetic material powder is random. Therefore, the interval between the soft magnetic powders contained in the magnetic material is wide on average in any direction, and as a result, the magnetic permeability in any direction is small, and the effect of leakage of electromagnetic waves and noise is sufficiently reduced. There is a problem that it cannot be reduced. On the other hand, in recent years, since most electronic devices generate electromagnetic waves, malfunctions of other electronic devices due to electromagnetic waves leaked from the electronic devices (malfunctions due to noise), obstacles to wireless communication, and human health It is considered that there is a problem with the impact on the environment. Therefore,
In order to prevent various obstacles due to such leakage of electromagnetic waves, a magnetic material with higher shielding performance against electromagnetic waves and with flexibility and flexibility that can be processed into various shapes as a cover for electronic devices of various shapes The appearance of the body is desired.

The present invention has been made in view of the above problems, and has as its main object to provide a method for manufacturing a magnetic material having higher flexibility and flexibility with higher shielding performance against electromagnetic waves. Another object of the present invention is to provide a magnetic body having higher flexibility and flexibility in shielding performance against electromagnetic waves. Another object of the present invention is to provide a cable that can reduce leakage of electromagnetic waves and reduce mixing of external noise.

[0005]

According to a first aspect of the present invention, there is provided a method of manufacturing a magnetic material, the method comprising: kneading a soft magnetic powder with a polymer material to prepare a magnetic material; A method for producing a magnetic material having a flexibility and flexibility by molding a raw material, the method comprising: applying a magnetic field when molding the magnetic material raw material; Characterized in that the soft magnetic powder is oriented in a predetermined direction.

A magnetic material according to a second aspect of the present invention is a magnetic material having flexibility and flexibility manufactured by molding a magnetic material obtained by kneading a soft magnetic material powder into a polymer material. It is characterized in that the body powder is oriented along a predetermined direction.

According to a third aspect of the present invention, there is provided the magnetic body according to the second aspect, wherein the magnetic body is formed in a sheet shape.

According to a fourth aspect of the present invention, there is provided a cable including a core wire and a coating covering the core wire, wherein the coating is formed by shaping a magnetic material obtained by kneading a soft magnetic material powder into a polymer material. The soft magnetic material powder is made of a magnetic material having flexibility and flexibility oriented along the circumferential direction of the coating.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings, in which: a method of manufacturing a magnetic body according to the present invention, a magnetic body manufactured according to the manufacturing method, and a cable using the magnetic body as a coating; An embodiment will be described.

First, a method for manufacturing a magnetic body according to the present invention will be described with reference to FIG.

First, a polymer material (natural rubber or various synthetic rubbers such as chlorobutylene or silicon rubber) is mixed with a soft magnetic powder (sintered ferrite powder, iron powder, nickel powder, cobalt powder, or a mixture thereof). , An alloy powder of this kind of metal is kneaded to produce a magnetic material. In this case, for example, the polymer material and the soft magnetic material powder are respectively charged into the tank at a predetermined ratio, and are uniformly kneaded by stirring with stirring blades.

Subsequently, the magnetic material is molded into a desired shape using a mold or the like while applying a magnetic field, thereby producing a rubber-like magnetic material 1 having flexibility and flexibility. In this case, the soft magnetic powder is usually not a perfect spherical shape but a distorted shape, and in a state where the polymer material is not solidified, a state in which the posture and position can be freely changed in the polymer material. Have maintained. Next, a magnetic field generation by a permanent magnet, an electromagnet, an electromagnetic coil, or the like is performed so that the direction A of the line of magnetic force passing through the magnetic material (the direction of application of the magnetic field) A and the direction B of increasing the magnetic permeability in the magnetic material 1 to be manufactured match. A magnetic field is formed using the means 2. In this case, by applying an external magnetic field to the unsolidified polymer material,
Magnetic poles of different polarities are generated at both ends along the longitudinal direction, and at the same time, a force from the magnetic field acts on each magnetic pole in parallel with the direction of the magnetic field. As a result, by changing the posture and position so that each soft magnetic material powder follows the direction of the magnetic field according to the magnetic moment at that time,
The direction of each soft magnetic material powder is aligned with the direction B of the magnetic field (so-called oriented state). Thereafter, the polymer material is solidified while each soft magnetic material powder remains oriented. Thereby, a rubber-like magnetic body 1 having anisotropy in which the magnetic permeability in the specific direction B (orientation direction) is higher than the magnetic permeability in other directions, and having flexibility and flexibility is manufactured. Is done. When the magnetic body 1 is formed into a predetermined shape (for example, a column shape or a sheet shape), there are various forming methods such as injection extrusion molding and rolling molding using rollers instead of molding using a mold. Can be adopted.

Next, the coil 3 using the magnetic material 1 for the magnetic core
A description will be given of a performance comparison with the coil 3A using an unoriented magnetic material for the magnetic core. As shown in FIG.
Is composed of a winding 4 and a magnetic core 5 using the magnetic body 1, and the coil 3A is made of the same material (polymer material and soft magnetic material) as the winding 4 and the material of the magnetic body 1 at the same ratio. And a magnetic core 5A that is formed without being oriented while being used. In the performance comparison test between the two, the impedance characteristics of the coils 3 and 3A when the frequency of the alternating current conducted through the winding 4 was changed by using the magnetic cores 5 and 5A for the same winding 4 respectively were measured. did. In addition, as a comparative example, the impedance characteristics of an air-core coil composed of only the winding 4 without using a magnetic core were also measured. In this case, the winding 4
Is formed to a diameter of 9 mm by winding a tin-plated copper wire having a diameter of 0.7 mm for 5 turns, and each of the magnetic cores 5 and 5A is 22 × 6 × 5.
It is formed into a 5 mm rectangular parallelepiped. Further, the orientation direction of the magnetic core 5 was made to coincide with the direction A of the magnetic field generated in the coil 3. The measurement results are shown in FIG. 3. As shown in FIG. 3, the coil 3 using the oriented core 5 is compared with the coil 4 using the unoriented core 5 </ b> A and the air-core coil. Has a clearly high impedance over a wide frequency band. Therefore, it was confirmed that the magnetic permeability in the alignment direction was surely increased by the alignment. According to the coil 3, by manufacturing the magnetic core 5 using the magnetic body 1, a coil having a small impedance and a high impedance can be realized.

Next, an example in which the magnetic body 1 is applied to the shielding sheet 11 will be described with reference to FIG. As shown in the figure, the shielding sheet 11 was produced by molding the magnetic body 1 into a sheet shape. In this case, as an example, the shielding sheet 11 is formed by orienting the soft magnetic material powder along the direction B in FIG. According to this shielding sheet 11, since the magnetic body 1 has flexibility and flexibility, objects of various shapes can be easily covered. Therefore, for example, by covering the electronic device that radiates electromagnetic waves with the shielding sheet 11, leakage of electromagnetic waves to the outside can be reduced, and external noise can be reduced to prevent malfunction of the electronic device.

Next, an example in which the shielding sheet 11 is applied to cover a cable will be described with reference to FIG. As shown in the figure, the cable 21 was produced by winding the shielding sheet 11 around the core wire 22. According to the cable 21, it is possible to reduce the electromagnetic waves leaking from the core wire 22 and to reduce the mixing of external noise into the electric signal passing through the core wire 22. In this case, when a current is conducted to the core wire 22, a magnetic field is generated on a concentric circle centered on the core wire 22 due to the conduction of the current. For this reason, when winding the shielding sheet 11 around the core wire 22, the direction of the magnetic field generated due to the conduction of the current is made to coincide with the direction B of the orientation of the shielding sheet 11. Thereby, the shielding sheet 1
Since the magnetic permeability in the concentric direction centered on the core wire 22 in 1 increases, the impedance of the core wire 22 with respect to the conducting current increases. As a result, electromagnetic waves radiated from the core wire 22 can be suppressed. In addition, for the same reason, the impedance with respect to the external noise increases, so that the amount of the external noise mixed into the electric signal passing through the core wire 22 can be reduced.

Next, an example in which the magnetic material 1 is applied to a cable coating will be described with reference to FIG. As shown in the figure, a cable 31 using the magnetic body 1 for a coating 32 covering the core wire 22 was produced. In this case, the coating 32 was formed integrally with the core wire 22 such that the direction B of the orientation of the soft magnetic material powder in the coating 32 and the circumferential direction of the cable 31 coincided with each other. According to the cable 31, the sheath 32
Has a higher magnetic permeability in the circumferential direction than in other directions except the circumferential direction. Therefore, the cable 21
For the same reason as described above, it is possible to reduce electromagnetic waves radiated from the electric signal passing through the core wire 22 and also reduce the amount of external noise mixed into the electric signal passing through the core wire 22.

The present invention is not limited to the configuration shown in the embodiment of the present invention. For example, in the embodiment of the present invention, the shielding sheet 11 is made of the magnetic material 1 in which the orientation direction B of the shielding sheet 11 and the spreading direction (planar direction) of the shielding sheet 11 coincide with each other. By matching the thickness in the thickness direction of the shielding sheet 11, the magnetic permeability in the thickness direction can be increased. Further, the above-described cables 21 and 31 may be configured such that the core wire 22 is covered with the shielding sheet 11 or the covering 32 via an insulator.

[0018]

As described above, according to the method for manufacturing a magnetic material according to the first aspect, a magnetic field is applied during molding of the magnetic material to reduce the soft magnetic material powder contained in the magnetic material. A magnetic body having a higher magnetic permeability in a predetermined direction than the magnetic permeability in another direction can be manufactured.

According to the second aspect of the present invention, since the soft magnetic powder is oriented along a predetermined direction, the magnetic permeability in the predetermined direction is increased as compared with a non-oriented magnetic substance. be able to. Therefore, for example, when a magnetic core of a coil is formed using this magnetic material, the direction of the magnetic field generated in the coil is aligned with the orientation direction of the soft magnetic material powder contained in the magnetic core, so that non-oriented A coil having higher impedance can be manufactured as compared with a coil using the magnetic material of (1) for the magnetic core.

Further, according to the magnetic material of the third aspect,
Since it is formed in a sheet shape having flexibility and flexibility, it is possible to easily cover electronic devices and cables of various shapes that leak electromagnetic waves. As a result, the amount of leakage of electromagnetic waves can be easily and reliably reduced. be able to. This makes it possible to provide a magnetic material suitable for various EMC components.

According to the cable of the fourth aspect,
Since the direction of the magnetic field formed around the cable due to the conduction of electric current in the cable matches the orientation direction of the magnetic material used for the coating constituting the cable,
Electromagnetic waves radiated from the cable can be suppressed, and the amount of extraneous noise mixed into the electric signal passing through the cord can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a method for manufacturing a magnetic body 1 according to an embodiment of the present invention.

FIG. 2 shows a coil 3 using a magnetic core 5 made of a magnetic material 1 in which soft magnetic material powder is oriented, a coil 3A using a magnetic core 5A made of a non-oriented magnetic material, and an air-core coil. FIG. 2 is a configuration diagram of a measurement system for measuring a change in impedance of the measurement system.

FIG. 3 is a characteristic diagram showing impedance characteristics with respect to frequency for each coil measured by the measurement system shown in FIG. 2;

FIG. 4 is an external view of a shielding sheet 11 formed by molding the magnetic body 1 according to an embodiment of the present invention into a sheet shape.

FIG. 5 is an external view of a cable 21 formed by winding the shielding sheet 11 shown in FIG.

FIG. 6 is an external view of a cable 31 according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic body 2 Magnetic field generation means 3 Coil 5 Magnetic core 11 Shielding sheet 21, 31 Cable 22 Core wire 32 Coating A, B direction

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 5E041 AA11 AA14 AA17 BB03 CA01 HB17 5E062 CC04 CD05 CF01 CG02 5E321 AA21 AA23 BB31 BB33 BB44 CC16 GG05 GG07 GG09 5G313 AA10 AB05 AC07 AD03 AE08 AE09 AE10

Claims (4)

[Claims] 1. A method for manufacturing a magnetic material, comprising: kneading a soft magnetic material powder into a polymer material to produce a magnetic material, and then molding the magnetic material to produce a magnetic material having flexibility and flexibility. A method for producing a magnetic material, comprising applying a magnetic field when molding the magnetic material to orient the soft magnetic powder contained in the magnetic material in a predetermined direction. Method. 2. A magnetic material having flexibility and flexibility manufactured by molding a magnetic material obtained by kneading a soft magnetic material powder into a polymer material, wherein the soft magnetic material powder is oriented in a predetermined direction. A magnetic body characterized by being oriented along. 3. The magnetic body according to claim 2, wherein the magnetic body is formed in a sheet shape. 4. A cable having a core wire and a coating covering the core wire, wherein the coating is formed by molding a magnetic material obtained by kneading a soft magnetic material powder into a polymer material. A cable, wherein the soft magnetic powder is composed of a magnetic material having flexibility and flexibility oriented along a circumferential direction of the coating.