KR20190023112A - Carbon Paper Having Hybrid Materials of Carbon Microcoils-Carbon Nanocoils - Google Patents

Abstract

The present invention relates to carbon paper comprising carbon microcoil-carbon nanocoil hybrid materials. More particularly, the present invention, by forming carbon microcoil-carbon nanocoil hybrid materials, relates to carbon microcoil-carbon nanocoil hybrid carbon paper having broadband and improved electromagnetic wave absorption performance. According to the carbon paper of the present invention, there is an effect of providing electromagnetic wave absorption performance of the broadband ranging from a low frequency to a high frequency due to the carbon microcoil-carbon nanocoil hybrid material and providing the improved electromagnetic wave absorption performance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon paper having a carbon microcoil-carbon nanocoil hybrid material,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon paper including a carbon microcoil-carbon nanocoil hybrid material, and more particularly, to a carbon paper which is formed of a carbon nanocoil-carbon microcoil hybrid material and has a broad band, Carbon nanocoil hybrid carbon paper.

The frequency of electromagnetic waves has gradually increased due to the rapid development of electronic engineering and communication engineering, such as the development of communication technology and the advancement of the propagation induction technology of mobile objects, while the intervals between electronic devices have gradually narrowed. As a result, unwanted radiation has become easier and it has become more and more common to add interference or noise to neighboring electronic equipment or to be affected by neighboring equipment.

Especially, in 5G environment mobile communication, high frequency of 10 GHz or more is used, and electromagnetic interference is severely caused. Such electromagnetic wave interference causes information loss and malfunction of electronic devices. Designing electronic equipment so as to have no electromagnetic interference or to have adequate immunity against electromagnetic interference has become an essential requirement in recent years, and there is a need for development of shielding materials and technologies for this purpose.

Electromagnetic wave shielding is a combination of external reflection, internal reflection, and absorption effect. Electromagnetic wave shielding by electromagnetic wave reflection using materials having excellent electrical conductivity such as metal nanoparticles and carbon nanotubes , And a prior patent (Publication No. 10-2017-0064216) discloses an electromagnetic wave-shielding metal / carbon hybrid particle. However, in the high frequency region of 5G in the future, a material having an electromagnetic wave absorption mechanism is absolutely necessary as a material of electromagnetic wave shielding than a material having an electromagnetic wave reflection mechanism.

Although electromagnetic wave shielding materials conventionally used include metal powder and carbon nanotubes, shielding frequency bands of respective materials are different from each other, and there is no demand for electromagnetic wave shielding materials that can be universally used in a wide band. Particularly, a carbon material having conductivity, rigidity and light weight characteristics has been attracting attention from a conventional single metal material having a high processing cost and limited formability.

Korean Patent Publication No. 10-2017-0064216

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a carbon microcoil-carbon nanocoil hybrid material having a broad band and an improved electromagnetic wave absorption performance, which is formed of a carbon nanocoil- To provide carbon paper.

To achieve the above object, the carbon paper includes a carbon microcoil and a carbon nanocoil hybrid material composed of carbon nanocoils, and has an electromagnetic wave absorption performance.

The diameter of the carbon micro-coil may be 1 μm or more and 3 μm or less.

The electromagnetic wave absorption performance may be an electromagnetic wave absorption performance of 10 GHz to 26 GHz.

The thickness of the carbon paper may be 0.5 mm or more and 3 mm or less.

Carbon paper can have flexibility.

According to the carbon paper of the present invention, the carbon microcoil-carbon nanocoil hybrid material provides an improved electromagnetic wave absorption performance in a wide band from low frequency to high frequency.

1 is an FESEM image of a material according to Comparative Examples 10, 12 and 14.
2 is a graph showing the electromagnetic wave shielding efficiency of the carbon paper according to Comparative Example 10. Fig.
Figure 3 shows an FESEM image of a carbon microcoil material.
4 shows an FESEM image of a carbon nanocoil material.
5 is a graph comparing the electromagnetic wave shielding efficiencies of carbon paper according to Examples 4 and 5 and Comparative Examples 2 and 9.
6 is a view showing the action of the carbon paper according to the first embodiment of the present invention.
7 is a graph comparing electromagnetic wave shielding efficiencies of carbon paper according to Comparative Examples 10, 12 and 14 of the present invention.
8 is a graph showing the electromagnetic wave shielding efficiency of the carbon paper according to Comparative Example 11 of the present invention.
9 is a graph comparing electromagnetic wave shielding efficiencies of carbon paper according to Comparative Examples 2 to 8 of the present invention.
10 is an image showing the flexibility of the carbon paper according to the first embodiment of the present invention.
11 is a schematic view illustrating a process of manufacturing carbon paper according to the first embodiment of the present invention.
12 is a graph comparing electromagnetic wave shielding efficiencies of carbon paper according to Example 1 and Comparative Examples 1, 2, 11, and 13 of the present invention.
13 is a graph comparing the electromagnetic wave shielding efficiencies of the carbon paper according to Example 1 and Comparative Example 2
14 is a graph comparing the electromagnetic wave shielding efficiencies of carbon paper according to Example 1 and Comparative Example 15. Fig.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings according to the present invention.

The carbon paper of the present invention includes a carbon microcoil-carbon nanocoil hybrid material composed of a carbon microcoil and a carbon nanocoil, and has an electromagnetic wave absorption performance.

When an electromagnetic wave reaches an object, the electromagnetic wave propagates through absorption, external reflection, internal reflection, and transmission mechanism. At this time, the total of the effects of not transmitting the electromagnetic wave is referred to as a shielding effectiveness (SE), and the electromagnetic wave shielding efficiency can be expressed by the sum of absorption, external reflection efficiency, internal reflection efficiency, and transmission efficiency. This expression is expressed by the following equation (1).

SE _R represents shielding efficiency by reflection, SE _A represents shielding efficiency by absorption, SE _B represents shielding efficiency by internal reflection, ρ represents volume resistivity, f represents electromagnetic wave frequency, and t represents the thickness of the shielding material.

The unit of the electromagnetic wave efficiency is decibel (dB). If the electromagnetic wave absorption mechanism is 10 dB or more, the internal reflection mechanism can be ignored. According to Equation (1), as the frequency of electromagnetic waves increases, the efficiency due to external reflection decreases and the efficiency due to absorption increases. That is, as the mobile communication evolves to 5G, the material required for electromagnetic wave shielding by progressing to higher frequencies means that a substance that absorbs electromagnetic waves is absolutely necessary.

When an electromagnetic shielding material is implemented using only metal, its application is limited due to high processing cost and limitations in moldability. Accordingly, when a carbon material having conductivity, rigidity, and light weight characteristics is incorporated to realize an electromagnetic shielding material, it can be applied to various applications, and can exhibit light weight, high moldability, and cost reduction effect compared with metals.

Among the carbon materials, the carbon nanocoils have a spiral structure like a spring, and the carbon micro-coils have a double helix structure like DNA. The helical geometry can induce currents to generate magnetic force, and the induced magnetic forces grab the electrons to absorb the electromagnetic waves.

Figures 1 (a), (b) and (c) show FESEM images of the materials of Comparative Example 12, Comparative Example 10 and Comparative Example 14, respectively. From the image, it can be seen that the carbon materials are separated from each other rather than being mixed with each other, and they appear to be aggregated together. If the carbon materials are simply mixed without hybridization to form a material, the mixed materials are not well mixed with each other and are partially isolated, which hinders the stability of the electromagnetic wave shielding efficiency. 2 also shows that the electromagnetic wave shielding efficiency of the carbon paper of Comparative Example 10 made of carbon micro-coil only in the high frequency region of 75 GHz or more is uneven due to a large variation in measurement frequency.

One way to overcome this instability and non-uniformity is to control the diameter of the carbon material. The carbon micro-coil is uniformly distributed and may have a diameter of 1 μm or more and 3 μm or less. By the uniformity, the variation of the shielding effect according to a specific frequency can be reduced. Fig. 3 (a) shows an FESEM of a general carbon microcoil, and Fig. 3 (b) shows an FESEM image of a carbon microcoil having a uniform diameter. From FIG. 3 (b), it can be seen that the diameter of the carbon micro-coil whose diameter is uniformly controlled is 1 μm or more and 3 μm or less. Figures 4 (a) - (c) show FESEM images of carbon nanocoils at different scales, respectively.

Another way to overcome these problems is to hybridize the carbon materials. Carbon microcoil - Carbon nanocoil hybridization shows better electromagnetic shielding efficiency than carbon microcoil alone. As a result, electromagnetic shielding in the low frequency region can also be achieved. Fig. 5 shows that the carbon paper of the carbon microcoil-carbon nanocoil hybrid material has higher electromagnetic wave shielding efficiency than the material made of carbon micro-coil alone.

When hybridization is carried out, electron conduction channeling is formed to improve electric conductivity. Fig. 6 (a) is a view showing a carbon micro-coil before hybridization, and Fig. 6 (b) is a figure after hybridization with a carbon micro-coil-carbon nano-coil. The red line in Fig. 6 (b) represents this electron conduction channeling. Therefore, a stable and constant electromagnetic wave shielding improvement effect can be reproducibly obtained even in a low frequency range owing to the hybridization.

The electromagnetic wave absorption performance may be an electromagnetic wave absorption performance of 10 GHz to 26 GHz. As shown in FIG. 7, it is shown that carbon paper having a mixture of various carbon materials is shielded from broadband electromagnetic waves in the case of carbon paper, which is made of only pure carbon single material. Therefore, it can be deduced that the carbon paper of the carbon microcoil-carbon nanocoil hybrid material also shields the broadband electromagnetic waves.

The thickness of the carbon paper may be 0.5 mm or more and 3 mm or less. 9 shows that the electromagnetic wave shielding efficiency increases as the thickness of the carbon paper made of a single carbon microcoil material increases. According to Equation 1, since the function related to the thickness t is a function derived from the electromagnetic wave absorption mechanism, Carbon paper made of a single carbon micro-coil material exhibits an electromagnetic wave absorption mechanism and shows excellent electromagnetic wave shielding effect in a high frequency range. Through this, carbon paper of carbon microcoil-carbon nanocoil hybrid material also exhibits electromagnetic wave absorption mechanism and it can be deduced that electromagnetic wave shielding effect is excellent in high frequency range.

Carbon paper can have flexibility. As shown in Fig. 10, the carbon paper of the present invention has flexibility that can not be realized in a metal material. The above flexibility can be achieved by mixing the carbon material with a flexible polymer resin by an ultrasonic dispersion method. Examples of the flexible polymer resin include polyamide, polyester, polyurethane, polyethylene, polyvinyl chloride, polyvinylidene fluoride, polyvinyl alcohol, polyacrylonitrile and poly Propylene-based fibers, and natural resins such as cellulose-based, protein-based, and mineral-based fibers. However, the present invention is not limited thereto.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the contents of the present invention are not limited to the following examples.

{Example}

The evaporator used was a thermal evaporator, the chemical vaporizer used RF-PECVD, the evaporator used TCVD, and the catalyst was Ni (99.7%). C ₂ H ₂ was used as the carbon coil raw material gas, and SF ₆ was used as the additive gas.

1. Example 1

Forming a catalyst layer on a ceramic substrate by using an evaporator; subjecting the formed catalyst layer to hydrogen plasma treatment using a chemical vapor deposition apparatus; introducing a raw material gas and an additive gas; Carbon nanocoil hybrid material was obtained through a step of synthesizing and hybridization by applying +/- bias voltage in a vapor deposition apparatus during the process of synthesizing the hybrid material. The overall temperature of the manufacturing process was set at 850 ° C. The above material was mixed with 78 wt% polyurethane resin by an ultrasonic dispersion method to prepare a carbon paper having a thickness of 2.0 mm including a carbon microcoil-carbon nano-coil hybrid material. The manufacturing process is briefly shown in FIG.

2. Example 2

Carbon paper containing a carbon microcoil-carbon nanocoil hybrid material was prepared in the same manner as in Example 1 except that the overall temperature of the production process was set to 750 ° C.

3. Example 3

Carbon paper containing a carbon microcoil-carbon nanocoil hybrid material was prepared in the same manner as in Example 1, except that the overall temperature of the manufacturing process was set to 650 ° C.

4. Example 4

Carbon paper containing a carbon microcoil-carbon nanocoil hybrid material was prepared in the same manner as in Example 1, except that the weight percentage of the polyurethane resin was 88 weight%.

5. Example 5

Carbon paper containing a carbon microcoil-carbon nanocoil hybrid material was prepared in the same manner as in Example 1, except that the weight percentage of the polyurethane resin was 94% by weight.

6. Comparative Example 1

Forming a catalyst layer on a ceramic substrate by using an evaporator, treating the formed catalyst layer with a hydrogen plasma treatment using a chemical vapor deposition apparatus, forming a carbon nanocoil using a deposition apparatus after injecting a raw material gas and an additive gas To obtain a carbon nanocoil material. The overall temperature of the manufacturing process was set at 850 ° C. The material was mixed with 78 wt% polyurethane resin by an ultrasonic dispersion method to prepare a carbon paper having a thickness of 2.0 mm including a carbon nanocoil material.

7. Comparative Example 2

Forming a catalyst layer on a ceramic substrate by using an evaporator, performing a hydrogen plasma treatment using the chemical vapor deposition apparatus, forming a carbon microcoil using a deposition apparatus after injecting a source gas and an additive gas To obtain a carbon microcoil material. The overall temperature of the manufacturing process was set at 850 ° C. The material was mixed with 88 wt% polyurethane resin by an ultrasonic dispersion method to prepare a carbon paper having a thickness of 2.0 mm including a carbon microcoil material.

8. Comparative Example 3

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2, except that the thickness was 1.8 mm.

9. Comparative Example 4

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2 except that the thickness was 1.6 mm.

10. Comparative Example 5

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2 except that the thickness was 1.4 mm.

11. Comparative Example 6

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2 except that the thickness was 1.2 mm.

12. Comparative Example 7

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2, except that the thickness was 1.0 mm.

13. Comparative Example 8

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2, except that the thickness was 0.8 mm.

14. Comparative Example 9

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2, except that the weight percentage of the polyurethane resin was 94% by weight.

15. Comparative Example 10

Carbon paper containing a carbon microcoil material was prepared in the same manner as in Comparative Example 2, except that the carbon microcoil material was mixed with 35.2 wt% of a polyurethane resin and 58.8 wt% of dimethyl formaldehyde by an ultrasonic dispersion method .

16. Comparative Example 11

Forming a catalyst layer on a ceramic substrate by using an evaporator, performing a hydrogen plasma treatment using the chemical vapor deposition apparatus, forming carbon nanotubes using a deposition apparatus after injecting a source gas and an additive gas To obtain a carbon nanotube material. The overall temperature of the manufacturing process was set at 850 ° C. The material was mixed with 88 wt% polyurethane resin by ultrasonic dispersion to prepare a carbon paper having a thickness of 2.0 mm including a carbon nanotube material.

17. Comparative Example 12

Carbon paper containing carbon nanotube material was prepared in the same manner as in Comparative Example 11 except that the carbon nanotube material was mixed with 35.2 wt% of polyurethane resin and 58.8 wt% of dimethyl formaldehyde by ultrasonic dispersion method .

18. Comparative Example 13

Forming a catalyst layer on a ceramic substrate using an evaporator, treating the formed catalyst layer with a hydrogen plasma treatment using a chemical vapor deposition apparatus, injecting a source gas and an additive gas, and then depositing a carbon nanocoil and a carbon nanotube Carbon nano-coils and carbon nanotubes mixed material were obtained. The overall temperature of the manufacturing process was set at 850 ° C. The material was mixed with 78 wt% polyurethane resin by ultrasonic dispersion to prepare a carbon paper having a thickness of 2.0 mm including carbon nanocoils and carbon nanotube mixed material.

19. Comparative Example 14

Forming a catalyst layer on a ceramic substrate by using an evaporator, treating the formed catalyst layer with a hydrogen plasma treatment using a chemical vaporizer, injecting a raw material gas and an additive gas, and then using a carbon micro- Carbon micro-coils and carbon nanotubes mixed material were obtained. The overall temperature of the manufacturing process was set at 850 ° C. The above material was mixed with 35.2 wt% of a polyurethane resin and 58.8 wt% of dimethylformaldehyde (DMF) by ultrasonic dispersion to prepare a carbon paper having a thickness of 2.0 mm including a carbon micro-coil and a carbon nanotube mixed material.

20. Comparative Example 15

Aluminum foil, which is widely used as a shielding material, is prepared.

The conditions of Examples 1 to 5 and Comparative Examples 1 to 15 are shown in the following table.

CMC is carbon microcoil, CNC is carbon nanocoil, CNT is carbon nanovite, and Al is aluminum. CMC-CNC indicates that CMC and CNC are hybridized, and CNC, CNT and CMC and CNT indicate that CNC, CNT, CMC and CNT are mixed, respectively.

Furtherance Manufacturing temperature (캜) Thickness (mm) PU (% by weight) DMF (wt%) Example 1 CMC-CNC 850 2.0 78 0 Example 2 CMC-CNC 750 2.0 78 0 Example 3 CMC-CNC 650 2.0 78 0 Example 4 CMC-CNC 850 2.0 88 0 Example 5 CMC-CNC 850 2.0 94 0 Comparative Example 1 CNC 850 2.0 78 0 Comparative Example 2 CMC 850 2.0 88 0 Comparative Example 3 CMC 850 1.8 88 0 Comparative Example 4 CMC 850 1.6 88 0 Comparative Example 5 CMC 850 1.4 88 0 Comparative Example 6 CMC 850 1.2 88 0 Comparative Example 7 CMC 850 1.0 88 0 Comparative Example 8 CMC 850 0.8 88 0 Comparative Example 9 CMC 850 2.0 94 0 Comparative Example 10 CMC 850 2.0 35.2 58.8 Comparative Example 11 CNT 850 2.0 88 0 Comparative Example 12 CNT 850 2.0 35.2 58.8 Comparative Example 13 CNC, CNT 850 2.0 78 0 Comparative Example 14 CMC, CNT 850 2.0 35.2 58.8 Comparative Example 15 Al - - - -

{evaluation}

The shape of the material was measured using a field emission scanning electron microscope (FESEM), the electric conductivity was measured using a four-point probe, and the electromagnetic wave shielding efficiency was measured using ASTM D4935-99.

1. Carbon nanotube material vs. Analysis of electromagnetic wave shielding efficiency of carbon microcoil material

FIGS. 8 and 9 show carbon paper of Comparative Example 11 consisting only of carbon nanotubes which is a material for advancing the reflection mechanism among the electromagnetic wave shielding mechanisms, and Comparative Examples 2 and 3, which are made of carbon microcoils, which is a material for advancing the absorption mechanism, among electromagnetic wave shielding mechanisms. 8 carbon paper of the present invention.

In the case of the carbon paper of Comparative Example 11 from 0.5 GHz to 6.0 GHz, the reflection loss (the same concept as the electromagnetic wave shielding efficiency) gradually increased from 0 dB to 8.0 dB. However, in the carbon paper of Comparative Example 11, In the case of paper, it does not show meaningful results. However, in the case of the carbon paper of Comparative Example 11, the reflection loss decreased as the frequency of the carbon paper of Comparative Example 11 went down to about 2.0 dB at a frequency of 6.0 GHz or more, and decreased to about 2.0 dB at the frequency of 15.0 GHz. On the other hand, The reflection loss increases, and it can be confirmed that the measurement value is 20 dB or more in a high frequency range of 10.0 GHz or more.

2. Analysis of electromagnetic wave shielding efficiency according to thickness of carbon paper

On the other hand, in the case of the carbon paper of Comparative Examples 2 to 8 composed only of carbon micro-coil, the reflection loss was measured according to the thickness. FIG. 9 shows that the reflection loss value measured in the high frequency region increases as the thickness of the carbon paper increases Giving. The carbon paper of Comparative Examples 2 to 8 has the same structure as that of the electromagnetic wave absorbing mechanism of Comparative Examples 2 to 8 because the function of the thickness t is derived from the electromagnetic wave absorbing mechanism only when the thickness of the carbon paper increases, And again confirms the analysis result of Evaluation 1 showing that the electromagnetic wave shielding effect is much better in the high frequency region than that of the carbon paper of Comparative Example 11 composed of only carbon nanotubes.

3. Aluminum foil vs. Analysis of carbon paper electromagnetic wave shielding efficiency

As shown in Fig. 14, the electromagnetic wave shielding efficiency of the carbon paper of Example 1 is lower than the aluminum foil of Comparative Example 15 at frequencies lower than 3.0 GHz. However, at a measurement frequency of 3.0 GHz or higher, the shielding efficiency of the carbon paper does not decrease, whereas the efficiency of the aluminum foil decreases sharply. From this, it is confirmed that carbon paper excellent in electromagnetic wave absorption mechanism at 10 GHz or higher will be very suitable as electromagnetic shielding material.

4. Single material vs. Analysis of mixed electromagnetic wave shielding efficiency

As shown in FIG. 7, the carbon paper of Comparative Example 14, in which the carbon micro-coil was mixed with the carbon nanotubes, was more excellent in the electromagnetic wave shielding efficiency than the carbon paper of Comparative Example 10 which was made of only the carbon microcoil in the low frequency region of less than 2.5 GHz, It can be seen that the carbon paper of Comparative Example 14 in which the carbon micro-coil is mixed with the carbon nanotubes is superior to the carbon paper of Comparative Example 12 which is made of carbon nanotubes only at frequencies higher than 2.5 GHz.

These results show that the carbon paper shields a wide band of electromagnetic waves in the case of carbon paper made of a mixture of carbon materials rather than carbon paper made of a pure carbon single material.

5. Single material vs. Hybrid material electromagnetic wave shielding efficiency analysis

In FIG. 5, the red line represents the electromagnetic wave shielding efficiency of the carbon paper of Examples 4 and 5, and the black line represents the electromagnetic wave shielding efficiency of the carbon paper of Comparative Examples 2 and 9. From FIG. 5, it can be seen that the carbon paper of the carbon micro-coil-carbon nano-coil hybrid material has a higher electromagnetic wave shielding efficiency over the entire measurement period (1.25 to 4.0 GHz) than the material made of carbon micro-coil alone regardless of the weight percentage of the polyurethane have.

6. Single material vs. Analysis of electromagnetic wave shielding efficiency of mixed or hybrid material

As shown in FIG. 12, the carbon paper of Comparative Example 1 made of only carbon nanocoils has poor volume resistivity as compared with the carbon paper of Comparative Example 2, which is made of only carbon microcoils. However, it can be confirmed that the carbon paper of Example 1 including the carbon microcoil-carbon nano-coil hybrid material has a lower volume resistivity than that of the carbon paper of Comparative Example 2. [ That is, it can be confirmed that the electric conductivity is improved and the electromagnetic wave shielding efficiency is increased. The carbon paper of Comparative Example 13 in which the carbon nano-coils are mixed with the carbon nanotubes also shows an increase in the electromagnetic wave shielding efficiency as compared with the carbon paper of Comparative Example 11 made of only carbon nanotubes.

These results show that the electromagnetic wave shielding efficiency is improved in the case of carbon paper made by mixing or hybridizing various carbon materials rather than carbon paper made of a pure carbon single material.

7. Analysis of electromagnetic wave shielding efficiency according to measured temperature

13, the electric conductivity of the carbon paper of Example 1 including the carbon microcoil-carbon nano-coil hybrid material, that is, the electromagnetic wave shielding efficiency was lower than that of the carbon paper of Comparative Example 2 containing a material consisting only of carbon microcoils You can see excellent. This is due to the above-described electron conduction channeling formation. It can be seen from FIG. 13 that the electric conductivity is improved with increasing temperature, and it can be seen that the materials of Examples 1 and 2 have semiconductor characteristics.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications and variations without departing from the spirit and scope of the invention. Accordingly, the appended claims should include all such modifications and changes as fall within the true spirit of the invention.

Claims (5)

Carbon microcoils; And
Carbon nanocoils;
And a carbon microcoil-carbon nano-coil hybrid material composed of the carbon microcoil-carbon nano-coil hybrid material. The method according to claim 1,
Wherein the diameter of the carbon microcoil is not less than 1 占 퐉 and not more than 3 占 퐉. The method according to claim 1,
Wherein the electromagnetic wave absorption performance is an electromagnetic wave absorption performance of 10 GHz to 26 GHz. The method according to claim 1,
And a thickness of 0.5 mm or more and 3 mm or less. The method according to claim 1,
Wherein the carbon paper has flexibility.

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