JPH1048368A - Electromagnetic wave protection material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave protection material capable of reducing the effect of electromagnetic wave generating from various electric appliances on human body. SOLUTION: Clay with ignition loss of 20 to 70% containing ferrous and ferric of which contents are larger in the ferrous than in the ferric and containing also nitrogen is prepared. Desirably clay is that ignition loss is 30 to 50%, the content of the ferrous is 2 to 10% and the content of the ferric is 0.5 to 4% (provifrf that the content of the ferric is not larger than the content of ferrous) and the content of nitrogen is 100 to 1000ppm. Clay of this kind is produced in Uenohara area in Yamanashi prefecture. This clay is sintered on 700 to 1500 deg.C to obtain ceramics as an electromagnetic protection material. The sintering is desired to be done shutting out oxygen. If only this material is placed between various electric appliances and a human body, the effects of electromagnetic wave on human body can be reduced and human body is protected from various health effects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various electrical products (including electronic products) used in homes, offices and the like.
Also, the present invention relates to an electromagnetic wave protection material or an electromagnetic wave protection material used to block electromagnetic waves leaking from various electronic products.

[0002]

2. Description of the Related Art It is well known that electromagnetic waves leaking from electrical products, power transmission lines, and the like cause electromagnetic interference to other electrical products such as televisions, radios, and computers. In order to block such an electromagnetic wave, it is also known that an electromagnetic wave shielding material made of an aluminum foil or the like is used to cover a component or the like that causes the electromagnetic wave in an electric product. However, in recent years, it is feared that weak electromagnetic waves leaking from electrical products in normal use and not causing electromagnetic interference to other electrical products may adversely affect the human body. Have been. For example, it has been reported in other countries that electromagnetic waves generated from power lines, mobile phones or computers in normal use may cause health hazards such as childhood leukemia, headache, and skin pain. (The magazine "SAPIO 1995.5.22").

In order to remove such incentives, it is considered that a conventionally used electromagnetic wave shielding material made of aluminum foil or the like may be used to cover transmission lines, mobile phones, computers and the like. However, aside from power lines, mobile phones and computers cannot be covered entirely with electromagnetic shielding. This is because, if the display unit and the dial unit of the mobile phone, the screen of the computer, and the like are covered with the electromagnetic wave shielding material, the functions of the mobile phone and the like are impaired, and normal use becomes impossible. Further, the conventional electromagnetic wave shielding material mainly protects against an electric field, but does not sufficiently protect against a magnetic field.

[0004]

SUMMARY OF THE INVENTION Therefore, the present inventors have developed a technique that does not cover the entire surface of an electric product that generates electromagnetic waves.
They were looking for a substance that could protect electromagnetic waves (especially magnetic fields) simply by being in the vicinity of the electrical product. as a result,
Coincidentally, one of the inventors has already filed Japanese Patent Application No. Hei 7-28802.
The present inventors have found that a ceramic water detergent applied for a patent as No. 7 exhibits a unique electromagnetic wave protection performance suitable for the above-mentioned purpose, and arrived at the present invention.

[0005]

That is, the present invention has a loss on ignition of 20 to 70%, contains ferrous iron and ferric iron, and the content of ferrous iron is higher than that of ferric iron. The present invention relates to an electromagnetic wave protection material characterized by being obtained by sintering a large amount of nitrogen-containing clay at 700 to 1500 ° C., and an electromagnetic wave protection material using the electromagnetic wave protection material.

[0006] The electromagnetic wave shielding material according to the present invention is obtained by sintering a specific clay at 700 to 1500 ° C. As described in the specification of Japanese Patent Application No. 7-288027, the specific clay is a clay produced in Uenohara-cho, Yamanashi Prefecture (hereinafter referred to as "Uenohara clay"). This clay has a feature that the ignition loss is large as compared with other clays. The reason why the ignition loss is large is not clear, but it is considered that the content of the organic substance is relatively large. The measuring method of the loss on ignition is as follows. That is, the produced clay is dried at 110 ° C. for 5 hours to remove free water. Dry clay weight (X
After measuring g), the mixture is heated in an electric furnace at 500 ° C. until a constant weight is obtained (until no change in weight is observed). Assuming that the weight of the clay at the constant weight is (Yg), it is calculated by the following equation: loss on ignition (%) = [(X−Y) / X] × 100.

[0007] The loss on ignition of Uenohara clay is in the range of 30 to 50%, but in the present invention, clay having a range of about 20 to 70% can be used. Clays with a loss on ignition of less than 20% often do not provide protection against electromagnetic waves. On the other hand, if the ignition loss exceeds 70%, the content of the inorganic substance is reduced, and when the ceramic is sintered, the compressive strength and the bending strength are not sufficient, and it is difficult to handle. In particular, the burning loss is 30 to 30%, similar to Uenohara clay.
Preferably it is in the range of 50%.

[0008] The clay used in the present invention contains ferrous and ferric irons. And the content of ferrous iron is larger than the content of ferric iron. General clays contain only ferric iron and do not contain ferrous iron (for example, kaolin), but contain ferrous and ferric but have a higher ferric content. (Eg, clay from Shigaraki, Shiga, clay from Kutani, Ishikawa, clay from Unzen, Nagasaki). That is, the feature of the clay used in the present invention is that the content of ferrous iron is larger than the content of ferric iron. Thus, it is considered that the relatively large amount of ferrous iron causes the electromagnetic wave to exert a unique effect on it. It is to be noted that ferrous iron is generally contained in clay in the form of FeO, and ferric iron is generally contained in clay in the form of Fe ₂ O ₃ .

The contents of ferrous iron and ferric iron are preferably in the following proportions. That is, the content is preferably 2 to 10% of ferrous iron and 0.5 to 4% of ferric iron. However, as described above, the clay used in the present invention is based on the premise that the content of ferrous iron is larger than the content of ferric iron. When the content of ferrous iron is less than 2%, there is a tendency that it is difficult to exert a good protective action against electromagnetic waves. At present, it is difficult to find a clay having a ferrous content exceeding 10%. When the content of ferric iron exceeds 4%, the content of ferrous iron tends to be relatively small. Further, the content of ferric iron may be less than 0.5%, but usually some amount of ferric iron is inevitably mixed. In addition,% mentioned here is calculated on the basis of the weight of the dry clay used in the present invention, and means% by weight. The specific method of measuring the contents of ferrous iron and ferric iron is as follows. That is, after the clay is dried in the same manner as when measuring the loss on ignition, the amount of ferrous iron is measured by the potassium permanganate method (acidity of sulfuric acid), and the content% of ferrous iron is measured. In addition, ferric iron is measured by a reduction method based on the SnCl ₂ method, and the content of ferric iron is measured.

Most preferably, the ratio of the contents of ferrous and ferric (ferric / ferrous) is about 0.4 ± 0.1. Of course, in the present invention, (ferric / ferrous) <1
Should be fine, but the most preferable is 0.4 ±
It is 0.1. Clays with such a ratio exhibit a unique effect on electromagnetic waves.

The clay used in the present invention contains nitrogen (nitrogen atom). This nitrogen is considered to be derived from organic substances contained in the clay. Although it is not clear what kind of action nitrogen in clay plays, it can be estimated as follows. That is, when this clay is sintered, nitrogen becomes a gas (a gas having nitrogen atoms as constituent atoms, for example, NH ₃ or N ₂ ), and a large number of pores are formed in the obtained sintered body (ceramic). it is conceivable that. The pores serve to increase the surface area of the ceramic, and it is considered that the increased surface area has some effect on electromagnetic waves.

[0012] The nitrogen content in the clay used in the present invention is preferably 100 to 1000 ppm. If the nitrogen content is less than 100 ppm, the amount of nitrogen gas generated when the clay is sintered is small, and the resulting ceramic tends not to have many pores. At present, clays having a nitrogen content exceeding 1000 ppm are hard to find. Here, ppm mentioned here is calculated based on the weight of the dry clay used in the present invention, and means ppm by weight. The nitrogen content was measured using the Kjeldahl method after drying the clay in the same manner as when measuring the loss on ignition.

As described above, the ignition loss, ferrous content,
A representative example of a clay having a ferric content and a nitrogen content is a clay produced from the Uenohara district of Yamanashi prefecture. Uenohara clay has a burning loss of 30-50% and a ferrous iron content of 2-1.
0%, ferric content 0.5-4%, nitrogen content 1
00 to 1000 ppm. And the content of ferric iron does not become larger than the content of ferrous iron. In the present invention, it is possible to use clay other than Uenohara clay, but at present, no clay having performance comparable to Uenohara clay has been found. In the future, clays with performance comparable to Uenohara clay may be discovered, but as long as such clays have the composition described in claim 1, they are within the scope of the present invention. Should be recognized. Clays used in the present invention such as Uenohara clay include, in addition to the above-mentioned ferrous, ferric and nitrogen,
Various clay components contained in ordinary clay are contained. For example, SiO ₂ , Al ₂ O ₃ , TiO ₂ , Ca
O, MgO, K ₂ O, Na ₂ O, etc. are contained in an arbitrary amount (one or more components may be 0% by weight).

Next, the above-mentioned clay is formed into a predetermined shape and sintered. The sintering temperature is 700-1500
° C. If the sintering temperature is lower than 700 ° C., sintering becomes poor, and it becomes difficult to obtain ceramics having sufficient compressive strength and bending strength. Although the sintering temperature may be 1500 ° C. or higher, it is wasteful in terms of energy. The sintering time may be any time as long as the obtained ceramic has a predetermined strength. Generally, it is preferably about 1 to 10 hours, and most preferably about 5 hours.

At the time of sintering, other kinds of clay may be mixed in addition to the above-mentioned clay. The other kind of clay is a clay not having the composition described in claim 1, such as kaolin, clay, bentonite, clay from Shigaraki, Shiga, clay from Kutani, Ishikawa, clay from Unzen, Nagasaki, and the like. Is used. The amount of the other clay is preferably less than 50% by weight,
Most preferably, it is less than about 15% by weight. When the amount of the other kind of clay is increased, the effect of electromagnetic wave protection aimed at by the present invention tends to decrease.

In the sintering, it is preferable that the sintering is performed while oxygen is cut off. It is thought that by blocking oxygen, ferrous iron in the clay used in the present invention can be prevented from being oxidized to ferric iron. However, even in the case of sintering in the presence of oxygen, ferrous iron is less likely to change to ferric iron, since placing clay in a flame (oxidizing flame or reducing flame) makes it difficult for oxygen to contact the clay. Become. Therefore, the sintering in the present invention may be performed in the presence of oxygen. It is also preferable to perform sintering in a reducing atmosphere. For example, sintering may be performed while flowing hydrogen gas.
Also at this time, ferrous iron is not easily changed to ferric iron, which is preferable. Further, the sintering may be performed under an inert atmosphere.
For example, sintering may be performed while flowing nitrogen gas. Also at this time, ferrous iron is not easily changed to ferric iron, which is preferable.

When sintering the clay of the present invention, the form may be any form. For example, it may be in any form such as a fine powder, a sphere, a cylinder, a triangle, a quadratic prism, a spheroid, a regular hexahedron, and a fiber. When the electromagnetic wave protection material is used as it is, a rod-like shape such as a cylinder, a triangular prism, or a quadratic prism is preferable. When the electromagnetic wave protection material is mixed with a synthetic resin, a fine powder or a spherical shape is preferable. . Further, the size may be any size. When a rod-shaped material is used, the length is 10 to 70
what cross section of about ² size 1~10cm in cm are common. When a fine powder or a spherical powder is used, a powder having an average particle size of about 0.1 to 1000 μm is generally used. Surprisingly, when the clay of the invention is sintered, its volume increases. For example, 3mm in diameter
When the spherical clay is sintered, the resulting ceramic has a diameter of 6 mm. The reason for this is not clear, but at the time of sintering, the organic substance in the clay decomposes into a gas and diffuses outside, so the pressure of this gas causes the clay to expand and sinter in that state It is thought that it is from. In the present invention, the sintered clay may be used as it is, or a material obtained by sintering and pulverizing may be used as the material.

The ceramic obtained by sintering is extremely suitable as an electromagnetic wave shielding material. That is, the electromagnetic waves (particularly the magnetic field) generated from the electric product are reduced only by placing the ceramic near the electric product. This point will be demonstrated by examples described later. The method of using the electromagnetic wave protection material according to the present invention may be placed in the vicinity of an electric appliance, or may be attached to a human body, and any method may be used. in short,
What is necessary is just to make it exist between the electric product which is an electromagnetic wave generation source, and a human body.

Further, the electromagnetic wave protection material according to the present invention may be used as it is, or may be mixed or adhered to a synthetic resin or the like and used as an electromagnetic wave protection material. The latter can be used by mixing an electromagnetic wave protection material into a synthetic fiber or attaching an electromagnetic wave protection material to the surface of a synthetic fiber, and using a woven or woven garment (for example, an apron) as the electromagnetic wave protection material. May be. Also, after mixing the electromagnetic wave protection material into the synthetic resin, this synthetic resin is formed into a film to form a film, and this film is used as an electromagnetic wave protection material.
It may be stuck on the surface of an electric appliance. Alternatively, an electromagnetic wave protection material may be mixed in a paint containing a synthetic resin, and the paint may be used to print on the surface of clothes or electric appliances. It is particularly preferable that the electromagnetic wave protection material is used as an electromagnetic wave protection material by mixing or adhering it to an arbitrary portion of a synthetic resin sheet such as a knitted fabric, a nonwoven fabric, or a film. In addition, an arbitrary part here means
As described above, in the sense of including various aspects such as mixing in synthetic fibers, adhering to the surface of synthetic fibers, mixing in films, and printing on the surface of clothes made of knitted fabric or the like. I'm using

[0020]

【Example】

Example 1 A clay produced in the Uenohara district of Yamanashi prefecture was prepared. This clay had the following composition. The loss on ignition 30-50% ferrous content 2-10% ferric content from 0.5 to 4% nitrogen content 100~1000ppm other clay component balance the clay, such as SiO _2, and kneaded by a kneader High And earth. This high soil is extruded into a cylindrical shape using an Ek Pelleter,
Cut to length. Put this in a hot air dryer,
After drying at a temperature of 105 ° C. for 5 hours, it was placed in a firing furnace to cut off oxygen, and fired at 1200 ° C. for 5 hours, and the clay was sintered to obtain a rod-shaped ceramic having a circular cross section. This rod-shaped ceramic had a diameter of 1 cm and a length of 50 cm, and this rod-shaped ceramic was used as an electromagnetic wave protection material.

On the other hand, the Trinitron TV manufactured by Sony Corporation was turned on, and the magnetic field generated from the TV was measured at a position 30 cm away from the TV screen. The magnetic field strength at this position was 43 milligauss. The magnetic field was measured using a commercially available magnetic field meter (tradename: TRACER micro ELF, manufactured by Radiation Technology Inc.).

At a position 40 cm below the television screen,
The magnetic field was measured by placing the above-mentioned electromagnetic wave protection material prepared in advance. As a result, the strength of the magnetic field was 0.1 milligauss. As can be seen from the above, the electromagnetic wave protection material according to the first embodiment is only placed near the electromagnetic wave generation source, and the intensity of the magnetic field that spreads around the source is extremely reduced.

In addition, as a result of examining the state of ions in the air using an ion checker (manufactured by Kobe Denpa Co., Ltd.) in place of the above-mentioned magnetic field meter, if there is no electromagnetic wave protection material, the ion checker Swings to +, and when the electromagnetic wave protection material is present, the ion checker swings to-. In addition, the ion checker
It is generally sold as a device for measuring the state of ions in the air, and a swing to + indicates that the air is undesired for the human body (for example, the air is dirty). ,-Indicates that the air condition is favorable for the human body (for example, the air is clean).

Example 2 Using the same high earth as used in Example 1, a sphere was formed using a marmellaizer, and then dried and sintered in the same manner as in Example 1 to obtain a diameter of 5 mm. Spherical ceramics were obtained. This spherical ceramic was used as an electromagnetic wave protection material.

On the other hand, at a position 1 m away from the same television screen used in Example 1, the magnetic field generated from the television was measured by the same method as in Example 1. The magnetic field strength at this location ranged from 2 to 10 milligauss.
Then, 50 pieces of the above-mentioned electromagnetic wave protection materials prepared in advance were placed in a dish at the same position as in the case of Example 1, and the magnetic field was measured. As a result, the strength of the magnetic field became 0.1 milligauss or less. The state of air was examined using the ion checker used in Example 1. When the electromagnetic wave protection material was not present, the ion checker oscillated to +, and when the electromagnetic wave protection material was present, the ion checker was used. Fell to-.

Example 3 Using the high earth used in Example 1, fine powdery ceramics having an average particle size of 2 μm were obtained. This fine powdery ceramic 3
20 parts by weight of water-soluble maleated polybutadiene
Was added to 100 parts by weight of an aqueous solution containing, and dispersed using a homomixer to obtain a dispersion. After immersing the polyester raw yarn in this dispersion liquid, it was introduced into a dryer and heat-treated to obtain a polyester yarn having fine powdery ceramics adhered to the surface. The polyester yarn was knitted by a conventional method to produce underwear (undershirt). In addition, this underwear serves as an electromagnetic wave protection material.

This undergarment is used by workers who are particularly tired among workers who regularly use word processors and computers.
One month later, everyone answered that they could work comfortably. The measurement with a magnetic field meter or an ion checker was performed by such a sensory test because it was difficult to perform the measurement accurately because the underwear was in close contact with the human body.

Example 4 Fine powdery ceramics used in Example 3 were added to 100 parts by weight of an aqueous solution containing 30% by weight of a 10% acryl-modified water-soluble polyester resin (manufactured by Goo Chemical Industry Co., Ltd., plus coat). 5 parts by weight were added, and further 0.05 parts by weight of a basic dye was added, followed by sufficient stirring to obtain a dyeing liquor. Apply this dye solution to the surface of an acrylic nitrile sports shirt.
An image of a rectangular solid of 30 cm in width and 10 cm in length was printed by screen printing, and then heat-treated for printing.

A sports shirt with this print (this is an electromagnetic wave protection material) was worn on 10 word processors and computer workers in the same manner as in Example 3, and the work was continued. A month later, everyone answered that they could work comfortably.

Example 5 Using the high earth used in Example 1, a fine powdery ceramic having an average particle size of 1 μm was obtained. This fine powdery ceramic 3
0 parts by weight was put into 100 parts by weight of a polyvinylidene chloride resin melted by heating, kneaded with a Banbury mixer, and then passed through an extruder to produce a raw resin. This raw material resin was extruded from a slit die having a slit width of 20 μm, and immediately subjected to uniaxial stretching at a stretching ratio of 3 in the machine direction to obtain a film (this film is an electromagnetic wave protective material). Using this film, various electric appliances as electromagnetic wave generation sources were covered, and before and after covering, the strength of the magnetic field was measured with a magnetic field meter. Moreover, when covering with a film, the number of films was covered in the range of 1 to 5 and measured. The results were as shown in Table 1. When each electric product is covered with a film-made electromagnetic wave protection material, it is not necessary to cover the whole of each electric product but to use a portion that needs to be opened to the outside when the electric product is used (for example, an air suction port of an air conditioner,
Except for the air outlet, switch, etc.), other parts were covered.

[0031]

[Table 1] In addition, the measurement with the magnetic field meter
The test was performed at a position 30 cm away from each electric product. However, for a mobile phone, the measurement was performed by bringing a magnetic field meter into contact with the mobile phone. Further, it is needless to say that the magnetic field of each electric product is measured while the power is turned on and in use.

As can be seen from the results of Examples 1 and 2,
The electromagnetic wave protection materials according to the first and second embodiments reduce the strength of the magnetic field that propagates to the vicinity only by placing the material near the electromagnetic wave generation source. Further, as can be seen from the results of Examples 3 and 4, if the electromagnetic wave protection material made of a knitted or woven fabric to which the electromagnetic wave protection material is mixed or adhered is worn on the human body, the influence of the magnetic field on the human body can be avoided. Further, as can be seen from the results of Example 5, when various electric appliances are covered with the film-made electromagnetic wave shielding material mixed with the electromagnetic wave shielding material, the influence of the magnetic field from each electric appliance can be reduced.

[0033]

As described above, the electromagnetic wave protection material and the electromagnetic wave protection material according to the present invention can be obtained by simply placing the electromagnetic wave protection material between various electric products which are electromagnetic wave generation sources and the human body. The effect of the magnetic field generated from the human body on the human body can be prevented. That is, since the electromagnetic wave protection material (material) according to the present invention does not need to cover the entirety of various electrical products, it is sufficient that the electrical products remain in a usable state and can be present at any location. Without interfering with product functionality
This has the effect of reducing the effects of electromagnetic waves generated therefrom. And, by reducing the influence of the electromagnetic wave, there is an effect that the human body can be protected from various health damages caused by the electromagnetic wave generation source.

Claims (7)

[Claims] 1. A clay which has a loss on ignition of 20 to 70%, contains ferrous and ferric and has a higher ferrous content than ferric content, and a nitrogen-containing clay. 700-1
An electromagnetic wave protection material obtained by sintering at 500 ° C. 2. The ignition loss is 30 to 50%, the ferrous content is 2 to 10%, and the ferric content is 0.5 to 4% (however, the ferric content is An electromagnetic wave protection material obtained by sintering a clay having a nitrogen content of 100 to 1000 ppm at 700 to 1500 ° C. 3. A clay produced in the Uenohara district of Yamanashi prefecture,
An electromagnetic wave protection material obtained by sintering at 00 to 1500 ° C. 4. A clay produced in the Uenohara district of Yamanashi prefecture, having a loss on burning of 30 to 50% and a ferrous iron content of 2 to 2.
10%, the ferric content is 0.5 to 4% (however, the ferric content is not larger than the ferrous content), and the nitrogen content is 100 to 1000 ppm. An electromagnetic wave protection material obtained by sintering clay at 700 to 1500 ° C. 5. A mixed clay obtained by mixing a clay described in any one of claims 1 to 4 with another clay,
An electromagnetic wave protection material obtained by sintering at 1500 ° C. 6. The electromagnetic wave protection material according to claim 1, wherein when sintering at 700 to 1500 ° C., sintering is performed while blocking oxygen. 7. A sheet-like electromagnetic wave protection material, wherein the electromagnetic wave protection material according to any one of claims 1 to 6 is mixed or attached to an arbitrary portion of a synthetic resin sheet-like material. .