JPH10102626A - Manufacturing method of radio wave absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond a carbon fiber bundle composed of a large number of carbon long fibers to a support material, for example, a back surface of a panel material for an outer wall of a high-rise building, at a predetermined interval from each other. Provide a way. SOLUTION: An adhesive is applied to a carbon fiber while rewinding the carbon fiber from a bobbin, and then a large number of the carbon fiber bundles are arranged in parallel with each other at a predetermined interval, and the bundles are collectively pressed against a supporting material to be bonded. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a radio wave absorber, and more particularly, to a method of using a carbon fiber bundle in which a large number of long carbon fibers are aligned in parallel to form a large number of carbon fiber bundles on a support. The present invention relates to a method of manufacturing a radio wave absorbing material bonded in parallel with each other. In this specification, the carbon fiber bundle means a plurality of carbon fibers obtained from a carbon fiber manufacturing process which are aligned in parallel and bundled with a sizing agent. Furthermore, it may mean that a plurality of these are collected and united. The radio wave absorbing material produced by the method of the present invention is used, for example, as a surface covering material for an outer wall panel of a high-rise building.

[0002]

2. Description of the Related Art As the number of high-rise buildings increases, radio wave interference of televisions frequently occurs. This is because the radio waves of television are reflected by a high-rise building. As a countermeasure, a radio wave absorbing material such as a ferrite tile is attached to the wall of the high-rise building.

[0003]

However, the method of attaching a ferrite tile to the wall of a high-rise building has several problems and cannot be said to be satisfactory. One of the problems is that ferrite tiles have a high specific gravity and the building skeleton must be reinforced to support its weight. There is also a problem that the design of the wall is restricted.

As another method for imparting radio wave absorption to the wall surface of a high-rise building, there has been proposed a method of using a carbon fiber bundle formed by collecting a large number of long carbon fibers having a large volume specific electric resistivity and binding them with a binder. (See Japanese Patent Application No. 8-62617). That is, first, tiles and other surface covering materials are laid on the bottom surface of the concrete panel formwork constituting the wall surface of the high-rise building with the back side up, and the above carbon fiber bundles are placed in parallel on it at intervals. After placing rebar parallel to the carbon fiber bundle and at a distance from each other, the concrete is poured and cured so that the rebar is completely buried. Excellent concrete panels can be manufactured. In this panel, a layer of carbon fiber bundles arranged in parallel at intervals functions as a radio wave absorption layer, and a layer of reinforcing bars arranged at a certain distance from this layer and parallel to the carbon fiber bundles. Functions as a radio wave reflection layer, and the concrete between both layers functions as a dielectric layer. In a radio wave absorber having a radio wave absorbing layer made of a carbon fiber bundle, such as a concrete panel, the carbon fiber is formed by the volume specific electric resistivity of the carbon long fiber constituting the carbon fiber bundle and the thickness of the carbon fiber bundle. It is known that there is an optimum value for the interval between bundles, and it is important to arrange carbon fiber bundles at an interval close to this optimum value in producing a concrete panel excellent in radio wave absorption. However, it is troublesome to arrange the carbon fiber bundles one by one at a predetermined interval on the facing material when manufacturing the concrete panel, and it is not preferable from the viewpoint of increasing the productivity of manufacturing the concrete panel. Usually, carbon fibers are supplied in a state in which a bundle of carbon fibers in which thousands to tens of thousands of carbon fibers are bundled is wound on a bobbin. Can be arranged in parallel.

[0005]

According to the present invention, the following steps (1) to (8) are carried out so that the carbon fiber bundles can be easily placed on the support at a predetermined interval. Can be placed and glued. (1) Arranging the support at a predetermined position (2) Rotatingly installing the required number of bobbins around the carbon fiber bundle on the bobbin support device (3) Pulling out the carbon fiber bundle from each bobbin Applying an adhesive to the carbon fiber bundle through an adhesive application device. (4) A plurality of carbon fiber bundles to which the adhesive has been applied are combined as required to produce a carbon fiber bundle in a radio wave absorber to be manufactured. Fixing to the first alignment plate so as to be equal to the interval between each other or an integer multiple thereof (5) Move the alignment plate while pulling the carbon fiber bundle,
(6) Fixing the carbon fiber bundle to the second alignment plate at the same interval as in the first alignment plate before the support (6) (2) Cutting the carbon fiber bundle so that the carbon fiber bundle on the support has a predetermined length while pulling between the two alignment plates.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail. In general, carbon fibers are produced in a state where thousands to tens of thousands of single fibers having a diameter of several μm to several tens μm are bundled. Then, such a carbon fiber bundle or a group in which a plurality of such carbon fiber bundles are further aggregated are bonded to a support to form a radio wave absorber. The thickness of the carbon fiber bundle on the support is
Usually, the total cross-sectional area of the carbon fiber constituting the carbon fiber is set to 0.
2~80mm ^2, preferably 0.8~20mm ^2.

[0007] As the support to which the carbon fiber bundle is adhered, usually, a flat plate such as a tile, a porcelain plate, a natural stone plate, or an artificial stone plate, which has been conventionally used as a surface covering material of a panel for a building outer wall, is used. . The support may consist of a single large facing, as in the case of large porcelain or artificial slabs, or a combination of a plurality of small facings, as in the case of tiles. Is also good. The size of the support is such that the length of the carbon fiber bundle adhered thereon is 40 mm.
It is preferably 0 mm or more, particularly 500 mm or more. When the length of the carbon fiber bundle on the support is short, the radio wave absorbing ability of the obtained radio wave absorbing material decreases.

In the present invention, as the support,
A flexible sheet-like material such as a woven fabric, a nonwoven fabric, a net, a blind, and the like can also be used. A radio wave absorber made by bonding a large number of carbon fiber bundles in parallel to such a flexible support can be used as it is to suspend it between walls or the like for radio wave absorption. It is used to manufacture a radio wave absorbing outer wall panel by attaching it to the back surface of a surface material of the outer wall panel (see Japanese Patent Application No. 8-79814).

The radio wave absorber manufactured by the present invention comprises a large number of carbon fiber bundles on any of the above-mentioned supports.
These are adhered in parallel with each other at predetermined intervals. The spacing between the carbon fiber bundles is determined by the thickness of the carbon fiber bundle (= the total cross-sectional area of the carbon fiber), the volume specific electrical resistivity of the carbon fiber, and the wavelength of the radio wave to be absorbed. Usually 5 to 300 mm, preferably 20 to 150 m
m.

In order to manufacture a radio wave absorbing material according to the present invention, first, a support is placed at a predetermined position. From the viewpoint of working efficiency, as shown in FIG. 1, it is preferable to arrange a plurality of supports sideways, that is, in a direction in which carbon fiber bundles are arranged in a finally obtained radio wave absorber. The bobbin around which the carbon fiber bundle is wound is rotatably installed on the bobbin support device. The number of bobbins is equal to the number of carbon fiber bundles to be bonded to the support in one operation described later. However, when several carbon fiber bundles are united and bonded to the support as one carbon fiber bundle, each carbon fiber bundle is added to the number of carbon fiber bundles bonded to the support in one operation. The number of bobbins multiplied by the number of carbon fiber bundles to be constituted is required.

When the above preparation is completed, the carbon fiber bundle is pulled out from each bobbin, and an adhesive is applied to the carbon fiber bundle via an adhesive application device. As the adhesive applying device, as shown in FIG. 1, a type in which a carbon fiber bundle is passed through an adhesive contained in a container is most simply used, but any other type such as an application roll is used. Can also be used. Examples of the adhesive include a heat-fusible adhesive such as asphalt, a thermosetting adhesive such as an epoxy resin and a phenol resin, and a water-soluble adhesive such as polyvinyl alcohol. Liquid adhesive can be used.

The carbon fiber bundle to which the adhesive has been applied is formed by combining a plurality of carbon fiber bundles into a single carbon fiber bundle, if desired, and then is arranged on the first alignment plate at a predetermined interval from each other. Fix it. Usually, it is fixed so as to have the same interval between the carbon fiber bundles in the finally obtained radio wave absorbing material, but if desired, it may be fixed at an integer multiple thereof. As the alignment plate, any plate can be used as long as it can fix a large number of carbon fiber bundles unwound from the bobbin and move them integrally. Normally, a long plate-shaped or rod-shaped member having a predetermined number of clips, for example, a number of clips, for holding and holding the carbon fiber bundle is used.

After the carbon fiber bundles are fixed on the first alignment plate, the alignment plate is moved while pulling the carbon fiber bundles, and the carbon fiber bundles are positioned on the support placed in advance.
Then, at a position just before the support, the carbon fiber bundle is fixed to the second alignment plate at the same interval as in the first alignment plate. The same as the first alignment plate can be used as the second alignment plate. Further, if the carbon fiber bundle is arranged at the same interval as the interval fixed to the alignment plate by the guide pin or the like while the carbon fiber bundle is rewound from the bobbin and sent to here, two plate-like members or Using an alignment plate composed of rod-shaped members, simply sandwiching the carbon fiber bundle between the two members, so that each carbon fiber bundle has a predetermined interval from each other,
It can be fixed to the second alignment plate.

By the above operation, the carbon fiber bundles are arranged between the two alignment plates so as to be parallel to each other at a predetermined interval, so that both the alignment plates are pulled and tension is applied to the carbon fiber bundles. Then, the carbon fiber bundle is pressed against and adhered to the support. Next, the carbon fiber bundle is cut so that the carbon fiber bundle adhered to the support has a predetermined length. Normally, it is preferable to arrange the carbon fiber bundle all over the width direction of the support. Therefore, the carbon fiber bundle is cut at both ends of the support.

Thus, one bonding operation is completed. When the carbon fiber bundle is adhered to only a part of the necessary portion of the support in one bonding operation, and when the carbon fiber bundle is disposed at an integral multiple of the arrangement interval of the carbon fiber bundle in the radio wave absorber finally obtained. In the case of bonding, the support is moved in a direction perpendicular to the bonding direction of the carbon fiber bundle, and the above operation is repeated, and finally, the carbon fiber bundle is bonded at a predetermined interval to all necessary parts of the support. So that However, in the second and subsequent bonding operations, since the end of the carbon fiber bundle is already fixed to the alignment plate, the operation of fixing the carbon fiber bundle to the first alignment plate is not performed in the above operation.

As the carbon long fibers constituting the carbon fiber bundle used in the present invention, it is necessary to use those having a large volume specific electric resistivity.
A material having a resistance of 0 ^-4 Ωcm to 10 ⁴ Ωcm is used. If a carbon fiber bundle composed of long carbon fibers having a smaller volume specific electric resistivity is used, generally no good radio wave absorption is exhibited. In addition, long carbon fibers having a volume specific electric resistivity larger than the above range are extremely unstable and fragile. The preferred volume specific electric resistivity of the carbon fiber is 10 ^-2 Ω · cm.
〜１０10 ² Ω · cm, especially 10 ⁻¹ Ω · cm to 10 ² Ω · c
m.

The long carbon fiber having such a specific volume resistivity has an optical anisotropy of 80% or more and a carbon content of 93%.
As described above, it can be manufactured by spinning a pitch having an ash content of 300 ppm or less, making it infusible, and then firing at 700 to 1000 ° C. As the raw material pitch, for example, coal-based coal tar, coal tar pitch, coal liquefaction, petroleum heavy oil, pitch, petroleum resin and its thermal polycondensation reaction product,
Carbonaceous raw materials such as a polymerization reaction product obtained by a catalytic reaction of naphthalene or anthracene are exemplified. In addition, these carbonaceous raw materials may be used after being subjected to a preliminary treatment such as a heat treatment followed by extraction of a soluble component with a solvent, a hydrogen-donating solvent, or a hydrogenation treatment in the presence of hydrogen gas. Good.

The raw material pitch contains ash (Ash component) as an insoluble substance. This is due to an optically anisotropic material which becomes a carbon fiber precursor by heating the raw material pitch. In the case of the liquid crystal pitch, it causes non-uniformity and gives a precursor of disordered structure. Further, after spinning, the fiber obtained by infusibilizing and firing produces physical defects, which adversely affects strength and elastic modulus.

Therefore, if a pitch having an ash content of usually 30 ppm or less, preferably 20 ppm or less is used at the stage of spinning, carbon fibers having high tensile strength can be obtained, and the carbon fiber bundle also serves as a reinforcing material. This is useful when used. The ash may be removed at any time before spinning, for example, at the raw material pitch stage or the spinning pitch stage. The ash may be removed by a known method. For example, there are a sedimentation method, a centrifugal separation method, a filtration method, an adsorption method, an acid, an alkali, a washing method with a solvent, and the like. May be repeated. It is also effective to add a porous inorganic substance (such as a filter aid) to increase the efficiency of removal. Industrially, it is preferable to use a sedimentation method, a centrifugal separation method, or a filtration method since continuous or large-scale treatment can be performed.

The pitch purified as described above is converted into a liquid crystal pitch having optical anisotropy according to a conventional method. The optical anisotropy ratio of the pitch used for spinning needs to be 80% or more, preferably 90% or more, and more preferably 95% or more. 80% optical anisotropy
If it is lower than the above, the strength of the carbon fiber is remarkably reduced, and if the firing temperature is increased to increase the tensile strength, the electric resistance is inevitably reduced, so that it is impossible to obtain a carbon filament having a desired high electric resistance.

The optical anisotropy ratio of the pitch is a value obtained by determining, as an area ratio, a portion showing the optical anisotropy in the pitch sample under a polarizing microscope at normal temperature. Specifically, for example, a pitch sample is crushed to a size of several mm square, and a sample piece is embedded in almost the entire surface of a resin having a diameter of about 2 cm according to a conventional method, and after polishing the surface, the entire surface is polarized. It is determined by observing under a microscope (100 times magnification) and measuring the area ratio of the optically anisotropic portion to the total surface area of the sample.

A method for producing an optically anisotropic liquid crystal pitch can also be performed by a known method. For example, the refined pitch is brought to 350-500 ° C., preferably 380-45 ° C.
At 0 ° C. for 2 minutes to 50 hours, preferably for 5 minutes to 5 hours, under an atmosphere of an inert gas such as nitrogen, argon, or steam,
Alternatively, there is a method of performing heat treatment under blowing or under reduced pressure. As another example, a method of polymerizing a condensed polycyclic hydrocarbon such as naphthalene in the presence of a catalyst such as HF / BF3, or performing a solvent separation using a solvent having a specific solubility parameter on a raw material pitch, There is a method for obtaining a desired pitch.

The carbon content of the spinning pitch is at least 93%, particularly preferably at least 95%. If the carbon content is less than 93%, as in the case of the above-mentioned ash, nitrogen, sulfur, oxygen, etc., which are foreign elements, cause a reduction in strength, and lower the tensile strength of carbon fibers. Melt spinning can be performed by a conventional method. Since the obtained pitch fiber has a low breaking strength as a single fiber, in order to prevent the generation of fluff on guides, rollers, and the like, 1,000 to 20,000 pitch fibers are bundled with a sizing agent to form a pitch fiber tow. I do. As the sizing agent, one that dissolves a part of the pitch fibers or adheres or fuses the fibers during the infusibilization treatment is required, and for example, a water emulsion of silicone oil is preferable. Further, in order to more effectively avoid fusion, inorganic fine particles such as carbon black and SiC may be added to the sizing agent.

The pitch fiber tow is heated to 160 to 400 ° C. in an oxidizing gas atmosphere to make it infusible. The obtained infusible fiber tow is calcined in an atmosphere of an inert gas such as nitrogen or argon to obtain a carbon fiber tow composed of long carbon fibers. In order to obtain the high-resistivity carbon long fiber used in the present invention, the calcination is performed at 700 to 1000 ° C., preferably 730 to 9100
It is carried out at 00 ° C, more preferably at 750-850 ° C. If the firing temperature is lower than 700 ° C., the strength and the radio wave absorption characteristics are not sufficient, and if the firing temperature exceeds 1000 ° C., only carbon fibers having low electric resistance can be obtained.

The long carbon fiber thus obtained has a high electric resistance and a property of high strength. Its volume specific electrical resistivity is 10 ^-4 Ω
· Cm or more is very easy and 10 ^-2 Ω
cm or more is not difficult. In addition, tensile strength 90
It is easy to provide mechanical strength of not less than kg / mm ^{2 and not} less than 3 ton / mm ² in tensile elasticity.
00kg / mm ² or more, more and 110 kg / mm ² or more tensile strength, 4 ton / mm ² or more, further 5ton
/ Mm ² or more. In addition, the tensile strength and the tensile elastic modulus here are based on JIS R7
601 is a value measured using a single fiber sample, and volume specific electrical resistivity is a value measured using a yarn sample according to JIS R7601.

An example of a method for producing a radio wave absorbing material according to the present invention will be described with reference to FIG.
Is unwound from the bobbin 2, the position between the carbon fiber bundles is regulated by the guide pins 3, and is introduced into the adhesive tank 5 containing the adhesive via the rollers 4. In the same way,
The adhesive adheres to the carbon fiber bundle 1 while advancing through the rollers 6 to 8. The carbon fiber bundle 1 passes through a roller 9,
After squeezing out the excess adhesive, the alignment plate 1
0 is attached. The aligning plate 10 moves on the back surface of the concrete panel covering materials 11 to 13 constituting the wall surface of the high-rise building which has been previously turned upside down while pulling the carbon fiber bundle 1, and moves the carbon fiber bundle 1 to the covering material. Position on top of 11-13. The size of the surface material is, for example, 600 × 900
〜1200 × 2400 mm. Next, the carbon fiber bundle is attached to the alignment plate 14, and the carbon fiber bundle 1 is applied to the facing material 11 while applying tension to the carbon fiber bundle 1 between the alignment plates 10 and 14.
After being pressed and bonded to 13, the cutting device 15 is operated to cut the carbon fiber bundle at the end of the facing material. Since the first bonding operation has been completed in the manner described above, the facing plates 11 to 13
Is moved upward in FIG. 1B, and a second bonding operation of moving the alignment plate 14 on the surface covering materials 11 to 13 while pulling the carbon fiber bundle is performed. By repeating this operation, the carbon fiber bundle can be easily adhered to the entire surface of the facing materials 11 to 13 at predetermined intervals. Instead of applying the adhesive to the carbon fiber bundle, an adhesive is applied in advance to the support to which the carbon fibers are bonded, or the carbon fiber bundle is pressed with an adhesive tape while the carbon fiber bundle is pressed against the support. Can be fixed to the support.

The carbon fiber bundle having the carbon fiber bundle adhered to the back surface of the facing material at a predetermined interval by the method of the present invention can be used as it is as a radio wave absorber. That is, by installing the carbon fiber bundle in the direction of arrival of the radio wave so as to be parallel to the direction of the electric field of the radio wave arriving, the radio wave can be efficiently absorbed. However, preferably, a radio wave can be more efficiently absorbed by providing a concrete portion having a reflective layer composed of a plurality of reinforcing bars parallel to the carbon fiber bundle on the back surface of the facing material. In this case, a common reinforcing bar can be used as the reinforcing layer, and the interval between the reinforcing bars is usually 25 to 200 mm, preferably 30 to 150 mm. The optimum distance (d) between the reflection layer made of reinforcing steel and the radio wave absorption layer made of the carbon fiber bundle is determined by the relative dielectric constant (ε) of concrete interposed between the two and the wavelength (λ) of the radio wave to be absorbed. ) And from
It is calculated by the following equation.

[0028]

## EQU1 ## d = λ / (4√ε)

Therefore, when the specific permittivity is increased by dispersing chopped strands of carbon fibers in the concrete, the thickness of the concrete can be reduced. Also, since concrete has a different dielectric constant depending on the water content, when the radio wave absorber according to the present invention is used for an outer wall of a high-rise building or the like, so that the water content of the concrete does not significantly change due to rainwater penetration or the like. It is preferable to mix a water repellent when placing ready-mixed concrete. This is because concrete containing a water-repellent agent has a significantly reduced absorption rate, so that a change in water content due to rainwater penetration or the like, and hence a change in relative dielectric constant is small.

One example of a method for producing a carbon fiber bundle used in the present invention is as follows. One part by weight of coal tar has a boiling point range of 240 parts.
After adding and mixing 1 part by weight of a previously hydrogenated aromatic oil at -290 ° C, a commercially available diatomaceous earth filter aid “Celite 505” (trade name, manufactured by Celite Co.) was used as a filter aid.
One part by weight is added, and filtration is performed through a candle filter having an opening of 10 μm. The obtained filtrate is heated at a temperature of 450.
C., and continuously supplied to an autoclave maintained at a hydrogen pressure of 150 kg / cm ² so that the average residence time is 60 minutes. The obtained reaction product is further filtered through a sintered filter having an opening of 0.5 μm, and the filtrate is distilled under reduced pressure to obtain a hydrogenated pitch. When the obtained hydrogenated pitch is heat-treated at 430 ° C. for 140 minutes under nitrogen gas bubbling, for example, at an optical anisotropy ratio of 100%, a Mettler softening point of 302 ° C., a carbon content of 96% by weight, and an ash content of 20 pp
A spinning pitch of about m is obtained.

Next, the spinning pitch is spun at a die temperature of 330 ° C. while being bundled with a silicone oil to obtain a continuous long pitch fiber tow having a fiber diameter of 13 μm and a number of filaments of 11,000. After the pitch fiber tow is infusibilized in air, it is fired in nitrogen gas at 800 ° C. for a residence time of 2 minutes to obtain a carbon fiber tow made of carbon long fibers. This carbon long fiber has, for example, a carbon content of 89%, a fiber diameter of 12.4 μ, a tensile strength of 100 kg / mm ² , a tensile elasticity of 5.0 ton / mm ² , and a high volume specific electric resistance of 3.5 Ω · cm. Indicates the rate. When this carbon fiber tow is directly solidified with an epoxy resin, a string-like carbon fiber bundle having a width of about 1.3 mm is obtained.

One example of manufacturing a radio wave absorber using this carbon fiber bundle is as follows: 600 × 900 × 13
A ceramic plate having a thickness of 1 mm is prepared, and a carbon fiber bundle is adhered to the back surface thereof at intervals of about 14 mm in parallel with the short side of the ceramic plate by the method of FIG. As the adhesive, a polyvinyl alcohol-based water-soluble liquid adhesive is used. Place this pottery plate in a mold with the back side facing up, and place it about 5 m thick at a position about 40 mm above the pottery plate.
A reinforcing bar assembly in which m reinforcing bars are arranged vertically and horizontally at an interval of 25 mm is installed such that one reinforcing bar is parallel to the short side of the ceramic plate. Next, the ready-mixed concrete is poured into the formwork, hardened well, cured at room temperature for about 3 weeks, and dried to obtain about 600 × 9
A radio wave absorber of 00 × 100 mm is obtained. The radio wave absorption characteristics of this radio wave absorber by the large waveguide method are shown in FIG.
And exhibits an absorption characteristic of about 22 dB at 600 MHz.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an example of an apparatus for implementing the present invention;
FIG. 1A is a front view, and FIG. 1B is a plan view (however, a cutting device is omitted in FIG. 1B).

FIG. 2 is a view showing one example of a radio wave absorber manufactured using a radio wave absorber obtained by the method of the present invention.

FIG. 3 is a view showing one example of a radio wave absorption characteristic of a radio wave absorber manufactured using the radio wave absorber obtained by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carbon fiber bundle 2 Bobbin 3 Guide pin 4 Roller 5 Adhesive tank 6 Roller 7 Roller 8 Roller 9 Roller 10 Alignment plate 11 Surface mounting material 12 Surface mounting material 13 Surface mounting material 14 Alignment plate 15 Cutting device 16 Reinforcing steel 17 Concrete

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Jin Hatashima Mitsubishi Chemical Co., Ltd. 2-5-2-2 Marunouchi, Chiyoda-ku, Tokyo

Claims (7)

[Claims] 1. A method of manufacturing a radio wave absorber in which a plurality of carbon fiber bundles comprising a plurality of carbon fibers are adhered in parallel on a support at intervals from each other, the method comprising at least the following steps: The manufacturing method characterized by the above-mentioned. (1) Arranging the support at a predetermined position (2) Rotatingly installing the required number of bobbins around the carbon fiber bundle on the bobbin support device (3) Pulling out the carbon fiber bundle from each bobbin Applying an adhesive to the carbon fiber bundle through an adhesive application device. (4) A plurality of carbon fiber bundles to which the adhesive has been applied are combined as required to produce a carbon fiber bundle in a radio wave absorber to be manufactured. Fixing to the first alignment plate so as to be equal to the interval between each other or an integer multiple thereof (5) Move the alignment plate while pulling the carbon fiber bundle,
(6) Fixing the carbon fiber bundle to the second alignment plate at the same interval as in the first alignment plate before the support (6) (2) Cutting the carbon fiber bundle so that the carbon fiber bundle on the support has a predetermined length while pulling between the two alignment plates. 2. The method for producing a radio wave absorber according to claim 1, wherein the support is a surface covering material of a building outer wall material. 3. The thickness of the carbon fiber bundle adhered on the support is 0.2 to 0.2% as the total cross-sectional area of the carbon fiber constituting the bundle.
The method for producing a radio wave absorber according to claim 1 or ² , wherein the thickness is 80 mm2. 4. A carbon fiber bundle on a support is 5 to 30
The method for producing a radio wave absorber according to any one of claims 1 to 3, wherein the bonding is performed at an interval of 0 mm. 5. The carbon fiber bundle having a volume specific electric resistivity of 1
The method for producing a radio wave absorber according to any one of claims 1 to 4, wherein a long carbon fiber of 0 ^-4 to 10 ⁴ Ω · cm is bound with a binder. 6. The carbon fiber bundle has a volume specific electric resistivity of 1
0 ^-2 ~10 ² Ω · cm manufacturing method of the radio wave absorber according to any one of claims 1 to 4, wherein the carbon filament is obtained by binding with a binding agent. 7. The apparatus according to claim 1, wherein the first alignment plate has a long plate-like or rod-like member and a holding member for holding and holding the carbon fiber bundle. A method for producing a radio wave absorbing material as described in Crab.