JP2007201113A - High intensity wave absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wave absorber with high intensity in which resin is set as a base material. <P>SOLUTION: A magnetic loss material such as magnetic powder is blended with resin reinforced by adding glass fiber or organic fiber and the wave absorber is manufactured. An addition amount of glass fiber or organic fiber is 10 to 50 vol.%. Organic fiber is either polyester or polyethylene. The percentage 5 vol.% or above of the magnetic loss material is blended. Conductive titanium oxide or a composite of conductive titanium oxide and conductive carbon black is blended. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio wave absorber that is used for prevention of interference caused by electromagnetic waves, and more particularly to a radio wave absorber that uses magnetic loss in a magnetic material.

  With the recent rapid spread of electronic devices such as mobile phones and game devices, failures due to electromagnetic waves that are considered to be caused by these electronic devices frequently occur. In particular, if an aircraft device or a medical device malfunctions due to electromagnetic interference, it may lead to a serious accident involving human life.

  The use of a radio wave absorber is one of the effective means for preventing such interference of electromagnetic waves.

  As one of the radio wave absorbers, one made of a magnetic radio wave absorber using magnetic loss is known (see, for example, Patent Document 1). This is an integrated magnetic powder such as ferrite mixed with a polymer compound such as resin, which acts on the magnetic field component of radio waves by the function of the imaginary part (magnetic loss term) of the complex permeability. Electromagnetic waves are absorbed by converting energy into heat.

However, in a magnetic wave absorber using magnetic loss, as shown in Patent Document 2, when a polymer compound such as a resin is used as a base material of a wave absorber, a connector portion of a power cord, a housing of an electronic device, etc. However, there remains a problem that the strength is insufficient to be used for the portion where the load is applied.
JP-A-6-232585 JP 2002-57485 A

  This invention is made | formed in view of such a subject, and it aims at providing the electromagnetic wave absorber with high intensity | strength and high performance.

  In order to achieve the above object, the present invention is a radio wave absorber formed by blending a magnetic loss material with a resin reinforced by adding glass fiber or organic fiber.

The addition amount of glass fiber or organic fiber is preferably 10 to 50% by volume.
As this organic fiber, polyester or polyethylene can be used.

The blending amount of the magnetic loss material is preferably 5.0% by volume or more.
Furthermore, it is preferable to mix conductive titanium oxide, which is a dielectric loss material, and conductive carbon black if desired.

  According to the invention configured as described above, it is possible to obtain a high-performance radio wave absorber having high strength reinforced by glass fibers or organic fibers.

  In the present invention, a glass fiber or an organic fiber is added to a resin serving as a base material of a radio wave absorber utilizing magnetic loss and reinforced, thereby providing a radio wave absorber with high strength and high performance.

  Moreover, in the present invention, a glass absorber or an organic fiber is added to a resin that becomes a base material of a radio wave absorber that combines dielectric loss and magnetic loss, and is strengthened by adding glass fiber or organic fiber to enhance the strength and performance. Can be provided.

Embodiments of the present invention will be described with reference to the drawings.
The radio wave absorber according to the present invention is a radio wave absorber formed by blending a magnetic loss material with a resin reinforced by adding glass fiber or organic fiber.

  For example, thermoplastic resins, thermosetting resins, various rubbers, elastomers, and the like are used as the resin serving as the base material of the radio wave absorber.

  The strength can be improved by adding glass fiber or organic fiber to such a resin. The glass fiber or the organic fiber is selected from the viewpoint that the relative dielectric constant is extremely low, that is, it is transparent to the radio wave so as not to affect the performance of the radio wave absorber.

  In addition, as organic fiber, polyester and polyethylene can be used, for example.

  By making the compounding quantity of these glass fiber or organic fiber into 10 to 50 volume%, intensity | strength can be made higher and workability can be made favorable.

  As the magnetic loss material, magnetic powder, for example, powder made of ferrite material is used. As the ferrite material, manganese-zinc, nickel-zinc, magnesium-zinc, copper-zinc, or the like can be used.

  For magnetic loss materials, if the blending amount is 5.0% by volume or more, the complex relative permeability of the material becomes an appropriate value for both the real part and the imaginary part, and the matching with the radio wave in the microwave band and the millimeter wave band is good. can do. The upper limit of the blending amount is not particularly specified, but is preferably 60% by volume or less from the viewpoint of improving workability.

  14.7% by volume of magnetic powder (Fukuda Metal's Fe-6Si-Flake, the same applies below) is added to polyamide resin (Mitsubishi Gas Chemical Reny 1091, the same applies below) reinforced with 30% glass short fiber added. A flat sample A was prepared from the injection-molded pellets.

  Further, a sample B on a flat plate was prepared from a pellet obtained by adding 20.5% by volume of magnetic powder to polyamide resin reinforced by adding 30% by volume of short glass fibers and injection molding.

  Further, Sample C on a flat plate was prepared from pellets obtained by injection molding of 6.1% by volume of conductive titanium oxide (FT-2000 made by Ishihara Sangyo) and 13.8% by volume of magnetic powder on the same base material as Sample B. .

  In addition, the compounding amount of the conductive titanium oxide and the magnetic powder in the sample C is determined to be almost the same as the compounding amount of the magnetic powder in the sample B.

  The results of measuring the magnetic permeability and the dielectric constant of these samples A, B, and C are shown in FIGS. 1 and 2, respectively. 1 and 2 are graphs in which the horizontal axis represents frequency and the vertical axis represents the values of the real part and the imaginary part of the complex relative permeability or complex relative permittivity.

  A radio wave absorber using a magnetic material as a material for radio wave absorption is designed based on characteristics of both magnetic permeability and dielectric constant.

  When a magnetic material is used as a material for a radio wave absorber, it is generally used in a frequency band where the imaginary part of the magnetic permeability is larger than the real part. The larger the value is, the thinner the wave absorber can be made.

  A flat sample A ′ having a thickness of 2.0 mm was prepared from the sample A, and a sample B ′ having a thickness of 5.8 mm was prepared from the sample B, and the results of measuring the radio wave absorption performance were shown in FIGS. Shown in 3 and 4 are graphs in which the horizontal axis represents frequency and the vertical axis represents absorption performance.

  From Fig. 3, it can be seen that the maximum value of the absorption performance of sample A 'is about 23 dB or more at around 6.0 GHz, and the frequency showing the absorption performance of 20 dB or more, which is a measure of excellent absorption performance, covers a wide range. .

  In addition, from FIG. 4, the maximum value of the absorption performance of sample B ′ is about 22 dB or more near about 1.9 GHz, and the frequency showing the absorption performance of 20 dB or more, which is a measure of excellent absorption performance, covers a wide range. I understand that.

  Therefore, it became clear that Samples A and B have excellent performance as a radio wave absorber.

  Furthermore, from FIG. 1, in sample C to which conductive titanium oxide, which is a dielectric loss material, was added, the frequency at which the imaginary part of the magnetic permeability is larger than the real part has moved to the lower frequency side than when not added, It can also be seen that the value of the imaginary part is also increased. This means that it is possible to obtain an electromagnetic wave absorber that is thinner and more effective from a lower frequency by using it in combination with a dielectric loss material than using a magnetic substance alone as in samples A and B. Is shown.

  Accordingly, FIG. 5 shows the result of producing a flat sample C ′ having a thickness of 4.0 mm from the sample C and measuring the radio wave absorption performance. FIG. 5 is a graph in which the horizontal axis represents frequency and the vertical axis represents absorption performance.

  As can be seen from FIG. 5, the maximum value of the absorption performance is about 30 dB or more around 1.94 GHz, and the frequency showing the absorption performance of 20 dB or more, which is a measure of excellent absorption performance, covers a wide range.

Therefore, it was revealed that this sample has excellent performance as a radio wave absorber.
Further, when this result is compared with FIG. 4 for the sample B, it can be seen that the frequency range showing the absorption performance of 20 dB or more is wide although the thickness of the sample is small.

  This indicates that the sample C has extremely excellent performance as a radio wave absorber.

It is a measurement result of the complex relative magnetic permeability of the electromagnetic wave absorber which concerns on this invention. It is a measurement result of the complex dielectric constant of the electromagnetic wave absorber which concerns on this invention. It is a graph which shows the electromagnetic wave absorption performance of the sample A which is an electromagnetic wave absorber which concerns on this invention. It is a graph which shows the electromagnetic wave absorption performance of the sample B which is an electromagnetic wave absorber which concerns on this invention. It is a graph which shows the electromagnetic wave absorption performance of the sample C which is an electromagnetic wave absorber which concerns on this invention.

Claims (5)

A radio wave absorber formed by adding a magnetic loss material to a resin reinforced by adding glass fiber or organic fiber. The radio wave absorber according to claim 1, wherein the glass fiber or the organic fiber is added in an amount of 10 to 50% by volume. The radio wave absorber according to claim 1, wherein the organic fiber is polyester or polyethylene. The electromagnetic wave absorber according to any one of claims 1 to 3, wherein the magnetic loss material is blended in an amount of 5.0% by volume or more. The electromagnetic wave absorber according to any one of claims 1 to 4, comprising a conductive titanium oxide or a composite of conductive titanium oxide and conductive carbon black.

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