JPS61210698A - Heterogenous medium wave reflection preventing material - 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 [Technical Field of the Invention] The present invention relates to a heterogeneous wave reflection prevention material that is used by being attached to the surface of an object that reflects radio waves in the air and sound waves in water.

[Prior art]

As a medium for wireless communication, radio waves are used in the air, and sound waves are used in water. However, these media have drawbacks such as diffuse reflection when there are obstacles such as offshore structures or ships near the communication path, which can cause ghosts and noise on the receiver and interfere with communication. .

For this reason, conventional practice has generally been to attach radio wave absorbing materials to the parts of such obstacles that are exposed in the air, and to attach sound absorbing materials to the parts submerged in water.

However, if this obstacle has a part that is submerged in the sea or exposed in the air, that part needs to have the function of both sound absorption and radio wave absorption in the different media of water and air. , these materials that can absorb radio waves and sound absorb, because the frequencies of sound waves and radio waves are significantly different.
No proposals have been made to date.

[Purpose of the invention]

The present invention relates to objects that reflect radio waves and sound waves (such as iron, wood, FRP, etc.) that can act as radio wave absorbing materials in the air and as sound absorbing materials in water.
The purpose of the present invention is to provide a material for preventing the reflection of waves in different media, which is used by being attached to the surface of materials (concrete, stone, etc.).

[Structure of the invention]

Therefore, in the present invention, an outer layer and an inner layer made of a rubber compound or a synthetic resin compound are integrally laminated, the outer layer contains conductive carbon, and the inner layer has a
The gist of the present invention is a heterogeneous wave reflection preventing material characterized by containing a filler having a particle size of 500 mesh.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory cross-sectional view of an example of the different-medium wave reflection preventing material of the present invention. In this figure, a different medium wave reflection preventing material 1 is formed by integrally laminating an outer layer 2 made of a rubber compound or a synthetic resin compound and an inner layer 3 made of a rubber compound or a synthetic resin compound. In order to laminate the outer layer 2 and the inner layer 3, they may be attached to each other using a suitable adhesive. Outside N
2 may have a single layer or multiple layers. In addition, the inner layer 3 here includes a top layer 3a, a first intermediate layer 3b, and a second intermediate layer 3c.
Although it is composed of four layers including +bottom layer 3d, it is sufficient to have at least one layer.

When using this different medium wave reflection preventing material 1, for example, an adhesive may be applied to the lower surface of the bottom layer 3d and the applied surface may be attached to the surface of the reflective object 4. In addition, the reflective object 4
After first pasting the bottom layer 3d on the surface of the second intermediate layer 3c,
, the first intermediate layer 3b.

The uppermost layer 1i3a and the outer layer 2 may be sequentially laminated.

(1) The outer layer 2 functions as a transmissive layer that takes in sound waves without reflecting them, and an absorption layer that absorbs radio waves without reflecting them. In order to prevent sound waves from being reflected, the specific acoustic impedance of water (in the case of seawater, the impedance (ρ
c) = 1.5 x 105 g/-.S). For this reason,
The outer layer 2 is made of a rubber compound or synthetic resin compound in which a vulcanizing agent or the like is added to rubber or synthetic resin, and the outer layer 2 has ρc=l. 3～2゜3X'
It was configured to take a value of l05g/c+a-s, which is very close to that of seawater (for reference, in the case of air: ρc = 40g/cJ-s, and in the case of steel: (I C = 4.6 Xl06g/ctA-s)
Note that this value of ρC can be obtained by appropriately selecting the ingredients and amounts of the rubber compound or synthetic resin compound.

Examples of the rubber used here include chloroprene rubber (CR) and nitrile rubber (NBR). Among these rubbers, CR is preferably used in consideration of processability and adhesiveness.

In addition, synthetic resins include, for example, vinyl chloride resin, Borie≠
These are thermoplastic resins such as polyurethane, or thermosetting resins such as phenol resins, epoxy resins, melamine resins, and polyester resins.

The outer layer 2 further contains conductive carbon. This is to improve radio wave absorption ability.

The conductive carbon is, for example, a powder of high structure carbon blank such as acetylene black or furnace black. In the case of acetylene carbon, the amount of conductive carbon contained is 30 to 60 parts by weight per 100 parts by weight of rubber or synthetic resin. This is because if the amount is less than 30 parts by weight, the mixture will have no electrical conductivity, while if it exceeds 60 parts by weight, the effect of the mixture will hardly change and processing will become difficult.

The thickness of this outer layer 2 is about 1 to 20 m.

(2) The inner layer N3 functions as a sound absorbing layer that absorbs sound waves. For this reason, it is made of a rubber compound or a synthetic resin compound and has a relatively large amount of filler inside. That is, sound absorption is achieved by converting and consuming sound wave energy into shear deformation in the vicinity of the filler. This is because medium particles on the same wavefront have different vibration velocities, and the relative velocities between these adjacent particles of different materials cause shear deformation and consume vibration energy. here,
The specific gravity of the filler is not specified, but the specific gravity is 2.0.
It is preferable that it is above.

This filler is shown as powder 5 in FIGS. 1 and 2.

The powder 5 is metal powder or inorganic powder with a particle size of 20 to 500 mesh. Examples of the metal powder include ferrite powder, aluminum powder, zinc powder, and copper oxide powder. Also,
Examples of the inorganic powder include calcium carbonate powder and mica powder.

The inner layer 3 contains at least one of these metal powders or inorganic powders.
It contains more than one type. The content thereof is not particularly limited, but may be at least 5 parts by weight per 100 parts by weight of rubber or synthetic resin.

Note that although most of the radio waves are absorbed by the outer layer 2, the radio waves that are partially transmitted enter the inner N3. Therefore, when using metal powder, it is preferable to increase the amount to about 300 to 400 parts by weight, which causes dimagnetic absorption of radio waves. That is, the inner layer 3 can completely absorb the radio waves that have passed through the inner layer 3 to some extent. In this case, 3
If it is less than 0.00 parts by weight, the radio wave absorption performance of the compound will be lost,
On the other hand, if it exceeds 400 parts by weight, the processability of the blend will deteriorate.

The thickness of this inner layer 3 is about 1 to 100H.

FIG. 3 is an example of the different medium wave reflection prevention material of the present invention,
As detailed in FIG. 1, the outer layer 2 made of rubber or a synthetic resin compound and the inner layer 3 made of a rubber or synthetic resin compound are integrally laminated. Both the outer layer and the inner layer are composed of one layer each, and the outer N2 functions as a transmission layer that takes in sound waves without reflecting them, and an absorption layer that absorbs radio waves without reflecting them. The inner layer 3 is a sound wave absorbing layer, is made of a rubber compound or a synthetic resin compound, contains the powder 5 described above, and absorbs sound energy. At this time, as described in Example 1 and described above, when the amount of metal powder mixed is increased, dimagnetic absorption occurs with respect to the incident radio waves, and the radio wave absorbability is improved. In addition, the particle size of the metal powder is preferably 100 to 500 mesh for sound absorption effect.

〔Effect of the invention〕

As explained above, according to the present invention, since the outer layer 2 and the inner layer 3 are configured as described above, they can function as a radio wave absorbing material and a sound absorbing material.

Therefore, the heterogeneous wave reflection preventing material of the present invention can be used both in the air and underwater.

Examples are shown below.

Example 1 8'' A sheet with a thickness of 10++n was made using the usual rubber product processing method using the following formulation A, and this sheet was heated at 160°C
The outer layer 2 was prepared by vulcanization by hot pressing for 30 minutes.

Compound A Chloroprene rubber 100 parts by weight Acetylene carbon 40 parts by weight Process oil
10 parts by weight anti-aging agent 1.5 parts by weight lubricant 2 parts by weight acid acceptor
4 parts by weight vulcanizing agent 5
Part by weight Vulcanization accelerator 0.5 part by weight
Inner N3 was prepared by hot press molding at 160°C for 30 minutes using the following formulation B.

The press used is controlled so that the product thickness is 3 mm.

Blend B Chloroprene rubber 100 parts by weight Furnace carbon 30 parts by weight Ferrite powder
310 parts by weight (200 mesh) Plasticizer 15 parts by weight Anti-aging agent
2 parts by weight Vulcanizing agent 4 parts by weight The above outer layer 2 and inner layer 3 were attached to the surface of the reflective object 4 via an adhesive. In this case, first, four plies of inner layer sheets (total thickness: 32 tm) were sequentially attached to the reflective object 4, and then one ply of outer layer sheets (total thickness: 10 m) was attached. As a result, radio wave absorption/sound absorption material (total thickness of 42m)
was gotten.

The radio wave and sound wave absorption performance of this product was as follows.

The measurement was performed by irradiating this product with waves of a certain frequency (radio waves or sound waves) at a certain intensity, and determining the return loss (dB) from the strength of the waves reflected from the product. Measurement results: Sound wave reflection loss in water: Frequency 10-300
It showed an effect of 10 dB or more at KH2, and 10 dB or more at radio wave reflection loss in the air: frequencies 8 to 12 GH2.

Example 2 SotoN2 was prepared by the blending method described in Example 1. However, the sheet thickness was 2. Inner layer 3 was prepared into a 2-inch thick sheet by heating and pressing in a mold at 160° C. for 30 minutes using the following formulation.

Compound C Chloroprene rubber 100 parts by weight Furnace carbon 30 parts by weight Mica powder (100 mesh) 10 parts by weight Plasticizer 15 parts by weight Anti-aging agent 2 parts by weight Vulcanizing agent
4 parts by weight of the obtained sheet outer layer 211 thickness,
Paste the inner layer 2 on the surface of the opposite object 4 in order, total 4
Atsushi Omo's thin-layer radio wave/sound wave absorber was obtained.

The absorption performance of this product was as follows.

■Sound wave reflection loss in water 2 frequencies 50~3゜0KH
10dB or more at 2, Radio wave return loss in the air:
It showed an effect of 10 dB or more at frequencies 8 to 1'2 GH2.

Example 3 The same method as in Example 1 was carried out except that the formulation B was replaced with the following formulation.

Compound D Chloroprene rubber 100 parts by weight Furnace carbon 40 parts by weight Plasticizer
16 parts by weight Anti-aging agent 3 parts by weight added
The absorption performance of this product containing 5 parts by weight of sulfur agent was as follows.

■Sound wave reflection loss in water: Frequency 10~1°OKH
10dB or more at 2, Radio wave return loss in the air:
It showed an effect of 10 dB or more at frequencies 8 to 12 GH2.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of an example of the different-medium wave reflection prevention material of the present invention, and FIG. 2 is an explanatory cross-sectional view taken along the line A--A. FIG. 3 shows another cross-sectional view of the different medium wave reflection preventing material of the present invention. 1... Different medium wave reflection prevention material, 2... Outer layer, 3...
・Inner layer, 4... Reflective object, 5... Powder. Agent Patent Attorney Nobuo Ogawa - Figure 2 Figure 3

Claims (1)

[Claims] An outer layer and an inner layer made of a rubber compound or a synthetic resin compound are integrally laminated, and the outer layer contains conductive carbon, and the inner layer is made of metal powder or inorganic powder with a particle size of 20 to 500 mesh. A foreign wave antireflection material characterized by containing at least one type of.