JPH10237415A - Electromagnetic wave shielding composition and electromagnetic wave shielding plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave shielding compsn. which can attenuate or intercept electromagnetic waves radiated by electric appliances (e.g. a portable telephone) and to provide an electromagnetic wave shielding plate prepd. by using the same. SOLUTION: This compsn. is prepd. by mixing a main component comprising 10-90wt.% silicone resin and 90-10wt.% baked ceramic with an aluminum powder and/or a stainless metal powder or is prepd. by mixing a main component comprising 10-90wt.% silicone resin and 90-10wt.% baked ceramic with a paint and an aluminum powder and/or a stainless metal powder. The shielding plate is prepd. by forming the compsn. into a thin plate with a thickness of 0.5-2.0mm and, if necessary, sticking an aluminum foil to one side of the thin plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding composition and an electromagnetic wave shielding plate for attenuating or blocking electromagnetic waves generated from electric equipment used everyday such as a portable telephone.

[0002]

2. Description of the Related Art Conventionally, as a material having the ability to block neutrons, 0.4 to 5.5% of boron and 0.1% of magnesium are used.
A neutron blocking aluminum alloy material is known in which an aluminum alloy consisting of 3 to 2.0%, silicon 0.2 to 1.8% and the remaining aluminum is used as a core material and pure aluminum skin is integrally provided on both surfaces of the core material. (Japanese Patent Publication 54
-88819). Further, a flame-retardant silicon composition having X-ray blocking ability, characterized in that a metal composition such as tungsten oxide is contained in a silicon composition containing platinum or a platinum compound as a flame retardant, has been proposed. (Japanese Unexamined Patent Publication No. 55-66799).

[0003] In these proposals, an aluminum alloy material is effective for blocking neutrons, and tungsten oxide,
This is based on the fact that titanium oxide and the like are effective.
These have been proposed as reactor shielding materials, silicon rubber compounds and the like.

[0004]

On the other hand, effective shielding means against electromagnetic waves generated from a short-wave transmission device built in a cellular phone, other household electric appliances, etc., which have spread rapidly in recent years, are still proposed. Absent. However, there is concern that electromagnetic waves emitted from mobile phones may have a considerable effect on human health, including the possibility of carcinogenicity.Therefore, it is important to protect the human body from electromagnetic waves emitted from mobile phones. A proposal for a member that can be made is desired.

[0005] At present, an apron, a filter, and the like are provided on the market under the advertisement of "capable of shielding electromagnetic waves". However, tests by consumer organizations have shown that these tools, although capable of blocking electric fields, have little ability to block electromagnetic waves.
In other words, there have been few proposals for effective measures to prevent damage from electromagnetic waves beforehand, and indirect measures such as "away from electrical appliances that generate electromagnetic waves as much as possible" and "reducing the use time and frequency of electrical appliances" Only measures have been proposed. Since the electromagnetic waves generated from mobile phones are generated from a position very close to the human brain, effective measures are required, but unfortunately, electromagnetic waves generated from mobile phones are Humans are almost defenseless (unshielded).

[0006]

Means for Solving the Problems The inventor of the present invention has obtained, as a result of numerous experiments, the knowledge that fired ceramics are effective in shielding electromagnetic waves or attenuating and absorbing electromagnetic waves. The present invention has been completed.

That is, the present application proposes an invention of an electromagnetic wave shielding composition and an electromagnetic wave shielding plate using the same, wherein the invention of the electromagnetic wave shielding composition comprises 10 to 90% by weight of a silicon resin and a fired ceramic. 90 to 10% by weight
And aluminum powder and / or stainless steel powder mixed with a main material obtained by mixing the above. In the above, the mixing ratio of the aluminum powder and / or the stainless steel powder to the main material composed of the silicon resin and the fired ceramic may be 3 to 10% by weight of the latter with respect to the main material. Also,
Here, when the aluminum powder and the stainless steel powder are mixed simultaneously with the main material, the aluminum powder and the stainless steel powder are mixed with aluminum powders 10 to 9
0% by weight and 90 to 10% by weight of stainless steel powder can be mixed.

Another electromagnetic wave shielding composition proposed by the present invention comprises a mixture of 10 to 90% by weight of a silicon resin and 90 to 10% by weight of a fired ceramic, and paint, aluminum powder and / or It is produced by mixing with stainless steel powder. Here, the mixing ratio of the paint and the aluminum powder and / or the powder of the stainless steel to the main material composed of the silicon resin and the fired ceramic can be set to 3 to 10% by weight based on the main material. . Here, when the paint and aluminum powder are mixed with the main material, or when the paint and the stainless metal powder are mixed, 10 to 90% by weight of the paint is mixed with the aluminum powder or the stainless metal. In the case where paint, aluminum powder and stainless steel powder are simultaneously mixed with the main material, paint and aluminum powder are mixed. The powder of stainless steel is a mixture of 10 to 80% by weight of paint, 10 to 80% by weight of aluminum powder, and 10 to 80% by weight of powder of stainless metal.

In the above, the stainless metal powder is one or more of platinum powder, platinum compound powder, stainless steel powder, titanium powder and magnesium powder, and the fired ceramic is granite, basalt, One or more kinds of sand are baked at 650 ° C. to 1200 ° C. for 6 hours or more, and cooled to room temperature.
It is produced by performing at least one step of firing at 0 ° C. for at least 6 hours and cooling to room temperature.

In the case of producing the above-mentioned electromagnetic wave shielding composition of the present invention, the main material is a silicone resin 10 to 9
Although it is composed of 0% by weight and 90 to 10% by weight of the fired ceramics, if each amount is less than 10% by weight, it is not preferable because the electromagnetic wave shielding ability rapidly decreases. On the other hand, when the respective amounts exceed 90% by weight, it is not preferable because even when the electromagnetic wave shielding plate of the present invention is used for a mobile phone, even the sound tends to be cut off.

In order to exhibit higher electromagnetic wave shielding ability, it is preferable that the main material is composed of 30 to 70% by weight of silicone resin and 70 to 30% by weight of fired ceramics.

The electromagnetic wave shielding composition of the present invention comprises (a) an aluminum powder, (b) a powder of stainless steel, (c) a mixture of aluminum powder and stainless steel powder, and (d) paint and aluminum powder. And (e) a mixture of paint and stainless steel powder, or (f) a mixture of paint, aluminum powder and stainless steel powder, mixed with the main material. It is generated. In any case, excellent electromagnetic wave shielding ability is exhibited, but in the order of excellent electromagnetic wave shielding ability, a mixture of paint, aluminum powder, and stainless steel powder is mixed with the main material. The following is a case where a mixture of paint and aluminum powder or a mixture of paint and stainless steel powder is mixed with the main material. Then
When the mixture of the aluminum powder and the stainless steel powder is mixed with the main material, the aluminum powder and the stainless steel powder are individually mixed. That is, when the paint is not mixed, the electromagnetic wave shielding ability (attenuating the electromagnetic waves,
Or the ability to absorb electromagnetic waves) is reduced by 20 to 10%.

In the present invention, the main material may include aluminum powder, stainless steel powder, a mixture of aluminum powder and stainless steel powder, a mixture of paint and aluminum powder, and a paint and stainless steel powder. And the mixture of paint, aluminum powder and stainless metal powder, the ratio of the latter being 3 to 10% by weight based on the main material. This is because if it is less than 3% by weight, the electromagnetic wave shielding ability is undesirably reduced. On the other hand, if it exceeds 10% by weight, when the electromagnetic wave shielding plate of the present invention is used in a mobile phone, even a sound tends to be blocked, which is not preferable.

In the case where aluminum powder and stainless steel powder are mixed simultaneously with the above-mentioned main material, the aluminum powder is 10 to 90% by weight, and the stainless steel powder 90% by weight.
The mixing is performed at a ratio of about 10% by weight to 10% by weight. This is because, when the respective amounts are less than 10% by weight, the electromagnetic wave shielding ability is lowered, which is not preferable. On the other hand, if it exceeds 90% by weight, when the electromagnetic wave shielding plate of the present invention is used for a mobile phone, even a sound tends to be blocked, which is not preferable.

Further, when the paint and aluminum powder or stainless metal powder are mixed with the main material, the paint and aluminum powder or stainless metal powder are mixed with 10 to 90% by weight of paint and aluminum. The powder or stainless steel powder is mixed at a ratio of 90 to 10% by weight.
If it is less than this, the electromagnetic wave shielding ability is lowered, which is not preferable. On the other hand, if it exceeds 90% by weight, when the electromagnetic wave shielding plate of the present invention is used for a mobile phone, even a sound tends to be blocked, which is not preferable.

When the paint, the aluminum powder and the stainless steel powder are mixed simultaneously with the main material, the paint, the aluminum powder and the stainless steel powder may be 10 to 80% by weight of the paint, Aluminum powder is mixed at a ratio of 10 to 80% by weight and stainless steel powder at a ratio of 10 to 80% by weight. However, when each amount is less than 10% by weight, the electromagnetic wave shielding ability is reduced. This is not desirable. On the other hand, if it exceeds 80% by weight, when the electromagnetic wave shielding plate of the present invention is used for a mobile phone, even a sound tends to be blocked, which is not preferable.

The fired ceramics constituting the main material may be one or more of granite, basalt and sand.
After firing at 0 ° C to 1200 ° C for 6 hours or more and cooling to room temperature, firing at 650 ° C to 1200 ° C for 6 hours or more and cooling to room temperature is performed at least once more. But the firing temperature is 650 ° C ~
The reason why the temperature was set to 1200 ° C. was to stabilize the physical properties of the material, and the step of cooling to room temperature after firing was performed twice or more because the material (such as granite) was used.
This is to equalize the relationship between the various components therein.

Next, an electromagnetic wave shielding plate proposed by the present invention is obtained by molding the above-mentioned electromagnetic wave shielding composition into a thin plate. Alternatively, it is obtained by layering an aluminum foil on one surface of the thin plate thus formed.

The thin electromagnetic wave shielding plate is 0.5 to 2 m.
A thickness of about m is sufficient, and this is formed into a shape and size (area) suitable for attachment to an electric device (for example, a mobile phone) which is required to shield electromagnetic waves. Can be used by attaching (for example, pasting) to an electromagnetic wave generating portion of the device.

In addition to forming the above-described electromagnetic wave shielding composition into a thin plate to obtain an electromagnetic wave shielding plate, an electromagnetic wave shielding plate is formed by coating an aluminum foil on one surface of the thin electromagnetic wave shielding plate. Can also. For example, the electromagnetic wave shielding plate is formed by laminating one surface of the thin electromagnetic wave shielding plate using aluminum as a foil. Even if the aluminum foil is not layered, sufficient electromagnetic wave shielding ability is exhibited. However, the electromagnetic wave shielding ability (electromagnetic wave absorbing ability) of about 40 to 50% is better when the aluminum foil is layered than when it is not. Increase.

According to the electromagnetic wave shielding composition of the present invention described above, electromagnetic waves can be shielded with high efficiency and reliability.
Alternatively, it can be attenuated.

Further, since this electromagnetic wave shielding composition has a high electromagnetic wave shielding ability, an effective electromagnetic wave shielding plate can be provided by forming it into a thin plate member having a thickness of about 0.5 mm to 2 mm.

Conventionally, aprons and filters provided on the market as having the ability to shield electromagnetic waves include:
Although there was an effect of removing the electric field, electromagnetic waves could hardly be blocked, but according to the electromagnetic wave shielding plate of the present invention, 66.1% at a distance of 5 cm from the mobile phone,
An epoch-making effect that an 85.5% electromagnetic wave attenuation rate can be achieved at a distance of 30 cm is exhibited.

Note that the electromagnetic wave attenuation rate in this specification is:
It is calculated as follows.

Electromagnetic wave attenuation rate = {1-10 ^{(AB) / 20} } × 100 (where A and B are measured when electromagnetic waves (unit: dBμV) are measured under the same measurement conditions, and A is The measured value when the electromagnetic wave shielding plate of the present invention is attached to an electric device that generates electromagnetic waves, and B is the measured value when the electromagnetic wave shielding plate of the present invention is not attached to an electric device that generates electromagnetic waves.) Once the electromagnetic wave shielding ability of the electromagnetic wave shielding composition and the electromagnetic wave shielding plate starts to exert its ability, it is semi-permanently maintained.

Since the thin electromagnetic wave shielding plate is flexible (has flexibility), it can be mounted along any surface shape of an electric device having any surface shape. . Therefore, a thin electromagnetic wave shielding plate can be attached to an electric device by a known attaching means (adhesive or the like) to efficiently attenuate or shield electromagnetic waves generated from the electric device.

Further, when the electromagnetic wave shielding plate of the present invention is attached to a mobile phone, not only can the electromagnetic waves generated from the mobile phone be blocked, but also the noise can be greatly suppressed to clear the call. There is also a secondary effect of being able to make calls on a mobile phone more comfortable.

[0028]

Embodiment 1 Hereinafter, a preferred embodiment of the present invention will be described.

A main material was formed by mixing 50% by weight of a silicon resin and 50% by weight of a fired ceramic. The fired ceramic used here is a basalt fired at 1000 ° C. for 8 hours, cooled to room temperature, fired again at 1000 ° C. for 8 hours, and cooled to room temperature.

5% by weight of aluminum powder was mixed with the above prepared main material to obtain an electromagnetic wave shielding composition of the present invention. In the same manner, 5% by weight of stainless steel powder, 5% by weight of a mixture of aluminum powder and stainless steel powder (mixed by 50% by weight), 5% by weight of a mixture of paint and aluminum powder (5
5% by weight of a mixture of paint and stainless steel powder (mixed by 50% by weight), 5% by weight of a mixture of paint and aluminum powder and 33.3% by weight of a mixture of paint, aluminum powder and stainless steel powder ) Was mixed at 5% by weight to obtain an electromagnetic wave shielding composition of the present invention. Thus, six kinds of electromagnetic wave shielding compositions were prepared. In addition,
The paint used here is a commercially available water-based paint.

These electromagnetic wave shielding compositions were formed into a thin plate having a thickness of 1 mm by pressure.
cm, a width of 5 mm, and a thickness of 1 mm. This was attached near the 800 MHz mobile phone antenna. When an electromagnetic wave was measured at a position 30 cm away from the speaker of the mobile phone in a state in which the mobile phone antenna was extended and talking, the attenuation rate of the electromagnetic wave was 78 compared to the case where the electromagnetic wave shielding plate was not attached. % To 90
%.

The greatest attenuation effect (electromagnetic wave shielding effect) was obtained when a mixture of paint, aluminum powder and stainless steel powder was mixed with the main material, and the attenuation effect (electromagnetic wave shielding effect) was small. In this case, aluminum powder alone or stainless steel powder alone was mixed with the main material.

Further, when the call state was confirmed, noise was reduced as compared with the case where the electromagnetic wave shielding plate was not attached, and the call was able to be performed more favorably.

[0034]

[Embodiment 2] A case where the electromagnetic wave shielding plate of the present invention is used by attaching it to a portable telephone. This will be described with reference to FIGS.

A main material was formed by mixing 50% by weight of a silicon resin and 50% by weight of a fired ceramic. The fired ceramics used here were obtained by firing granite at 1000 ° C. for 7 hours, cooling to room temperature, firing again at 1000 ° C. for 7 hours, and cooling to room temperature.

A mixture of paint and platinum powder was added to and mixed with the main material at a ratio of 6% by weight to obtain an electromagnetic wave shielding composition of the present invention. Here, a commercially available water-based paint was used as the paint, and the paint and platinum powder were 8
It was mixed at a ratio of 0% to 20% by weight.

The electromagnetic wave shielding composition thus produced was subjected to pressure molding to obtain a thin electromagnetic wave shielding plate 4 having a thickness of 2 mm.

An aluminum foil 5 was layered on one surface of the electromagnetic wave shielding plate 4, an adhesive layer 6 was applied to the outside of the aluminum foil 5, and a release paper 7 was stuck thereon to form the electromagnetic wave shielding plate 2. .

In order to attach the electromagnetic wave shielding plate 2 to the mobile phone 1, a desired size, for example, a length of 11 cm and a width of 5 cm
mm, the release paper 7 is peeled off, and attached to a position near the antenna 3 of the mobile phone, for example, as shown in FIG.

The size of the electromagnetic wave shielding plate 2 can be appropriately determined according to the size of an electric device which is a target object of electromagnetic wave shielding, the size of an electromagnetic wave generating portion, the frequency of an electromagnetic wave, and the like. For example, a frequency of 800 MHz or 1.
When used for a 9 GHz mobile phone, the length is 11 cm,
It can be used in the size of 4mm in width, and frequency 1.5G
Hz for mobile phones, length 7cm, width 4m
m.

The thickness is not limited to 2 mm, but a thickness of 2 mm is sufficient as an electromagnetic wave shielding ability, so that it is not particularly necessary to further increase the thickness.
On the other hand, if the thickness is too small, the electromagnetic wave shielding ability is reduced. Therefore, it is preferable that the thickness is at least 0.5 mm.

[0042]

[Test Example 1] The release paper 7 of the electromagnetic wave shielding plate 2 manufactured in Example 2 was peeled off, and as shown in FIG.
After attaching it near the antenna of the 53MHz mobile phone,
The electromagnetic waves during the call were measured. The electromagnetic wave measurement location is
Near the center of the speaker 8, 5 cm away, 3
The measurement was performed at a position separated by 0 cm. The results are shown below.

Distance from mobile phone 5 cm 30 cm When electromagnetic wave shielding plate 2 is attached 63.2 dbμV 45.7 dbμV When electromagnetic wave shielding plate 2 is not attached 72.6 dbμV 62.5 dbμV Electromagnetic wave attenuation 66.1% 85.5% In the experiment, the electromagnetic wave shielding plate 2 was attached to the mobile phone 1 as shown in FIG. 1, while the measurement of the electromagnetic wave was performed near the center of the speaker 8 at a distance of 5 cm or 30 cm from the mobile phone. That is, the measurement was performed in a state where the electromagnetic wave shielding plate 2 was not interposed between the mobile phone and the electromagnetic wave measurement position. Nevertheless, since the electromagnetic wave attenuation as described above was confirmed, the electromagnetic wave shielding composition and the electromagnetic wave shielding plate of the present invention absorb the generated electromagnetic wave rather than shielding the electromagnetic wave, and Is attenuated to prevent electromagnetic waves from leaking to the outside world.

It should be noted that for about 30 minutes immediately after the electromagnetic wave shielding plate 2 of the present invention was attached to the portable telephone, attenuation of electromagnetic waves could not be confirmed so much. The electromagnetic wave shielding composition and the electromagnetic wave shielding plate of the present invention are considered to be unable to sufficiently exhibit the ability to attenuate electromagnetic waves for a certain period of time after electromagnetic waves are started to be generated from the attached electric device, that is, for about 30 minutes. . However, if the ability to attenuate electromagnetic waves comes to be exhibited about 30 minutes after the wearing, the ability is maintained forever.

[0045]

According to the electromagnetic wave shielding composition of the present invention described above, electromagnetic waves can be shielded or attenuated with high efficiency and reliably.

Further, since this electromagnetic wave shielding composition has a high electromagnetic wave shielding ability, an effective electromagnetic wave shielding plate can be provided by molding it into a thin plate member having a thickness of about 0.5 mm to 2 mm.

Further, when the electromagnetic wave shielding plate of the present invention is attached to a mobile phone, not only can the electromagnetic waves generated from the mobile phone be blocked, but also the noise can be greatly suppressed to clear the call. There is also a secondary effect of being able to make calls on a mobile phone more comfortable.

[Brief description of the drawings]

FIG. 1 is a perspective view of a portable telephone equipped with an electromagnetic wave shielding plate of the present invention.

FIG. 2A is a perspective view of an electromagnetic wave shielding plate of the present invention.
(B) is a partial cross-sectional enlarged view of the electromagnetic wave shielding plate of the present invention illustrated in (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mobile phone 2, 4 Electromagnetic wave shielding plate 5 Aluminum foil 6 Adhesive layer 7 Release paper

Claims (15)

[Claims] An aluminum powder and / or a stainless metal powder is mixed with a main material obtained by mixing 10 to 90% by weight of a silicon resin and 90 to 10% by weight of a fired ceramic. A characteristic electromagnetic wave shielding composition. 2. An aluminum powder and / or 3-10% by weight ratio with respect to a main material obtained by mixing 10-90% by weight of a silicon resin and 90-10% by weight of a fired ceramic.
An electromagnetic wave shielding composition produced by mixing a stainless steel powder. 3. The aluminum powder and the stainless metal powder are mixed at a ratio of 10 to 90% by weight of the aluminum powder and 90 to 10% by weight of the stainless metal powder. An electromagnetic wave shielding composition. 4. The electromagnetic wave according to claim 1, wherein the stainless metal powder is one or more of platinum powder, platinum compound powder, stainless steel powder, titanium powder, and magnesium powder. Shielding composition. 5. The fired ceramic is granite, basalt,
One or more kinds of sand are calcined at 650 ° C. to 1200 ° C. for 6 hours or more, and cooled to room temperature.
Firing at 00 ° C. for 6 hours or more and cooling to room temperature,
The electromagnetic wave shielding composition according to claim 1, wherein the composition is produced by performing at least one time. 6. An electromagnetic wave shielding plate obtained by molding the electromagnetic wave shielding composition according to any one of claims 1 to 5 into a thin plate shape. 7. The electromagnetic wave shielding composition according to claim 1, wherein the composition is formed into a thin plate, and an aluminum foil is layered on one surface of the formed thin plate. Electromagnetic wave shielding plate. 8. A mixture obtained by mixing a paint and aluminum powder and / or stainless steel powder with respect to a main material obtained by mixing 10 to 90% by weight of a silicon resin and 90 to 10% by weight of a fired ceramic. An electromagnetic wave shielding composition, comprising: 9. A paint and aluminum powder and / or stainless steel powder are added in an amount of 3 to 10% by weight based on a main material obtained by mixing 10 to 90% by weight of a silicon resin and 90 to 10% by weight of a fired ceramic. %. An electromagnetic wave shielding composition produced by mixing at a ratio of 0.1%. 10. The paint and aluminum powder or stainless metal powder are mixed at a ratio of 10 to 90% by weight of paint and 90 to 10% by weight of aluminum powder or stainless metal powder. 10. The electromagnetic wave shielding composition according to 8 or 9. 11. The paint is mixed with aluminum powder and stainless steel powder at a ratio of 10 to 80% by weight of paint, 10 to 80% by weight of aluminum powder, and 10 to 80% by weight of stainless steel powder. The electromagnetic wave shielding composition according to claim 8 or 9, wherein the composition is characterized in that: 12. The electromagnetic wave according to claim 8, wherein the stainless metal powder is one or more of platinum powder, platinum compound powder, stainless steel powder, titanium powder, and magnesium powder. Shielding composition. 13. The fired ceramic is obtained by firing one or more of granite, basalt, and sand at 650 ° C. to 1200 ° C. for 6 hours or more and cooling to room temperature.
The electromagnetic wave shielding composition according to claim 8, wherein the composition is fired at 1200 ° C. for 6 hours or more and cooled to room temperature at least once more. 14. An electromagnetic wave shielding plate obtained by molding the electromagnetic wave shielding composition according to claim 8 into a thin plate shape. 15. An electromagnetic wave shielding, wherein the electromagnetic wave shielding composition according to claim 8 is formed into a thin plate, and an aluminum foil is layered on one surface of the formed thin plate. Board.