JPH0258352B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a carbon material containing boron and chlorine,
and a method for producing highly conductive carbon materials. [Prior Art] Conventionally, an organic boron compound monomer consisting of carbon, hydrogen, and boron is thermally decomposed on a substrate, and then
A method of obtaining a conductive graphite material by heat treatment is known. (Special application 1986-152678
Publication No.). In addition, chlorine has the effect of acting as a dehydrogenating agent when carbonizing organic polymers by firing, and it is known that the yield of carbon materials improves when carbonizing polymers in which hydrogen has been replaced with chlorine. ing. (PL Walker, Jr. ed. Chemistry and
Physics of Carbon, volume 7, pp328-332,
Published in 1971). [Problems to be Solved by the Invention] However, the method described in Japanese Patent Application No. 152,678/1980 has a slow deposition rate when depositing gas on a substrate by thermal decomposition, and also requires heat treatment. There were problems in that the conductivity and degree of carbonization of the carbon material were insufficient after treatment. Regarding chlorine, it is known that chlorine is effective in reducing the carbonization start temperature and improving carbon yield by promoting dehydrogenation. Nothing is known about its effects, especially its cocatalytic effect with boron. Furthermore, Japanese Patent Laid-Open No. 61-222116 describes doping with boron or the like when forming a deposited film using a compound containing carbon and halogen. However, this technique produced amorphous carbon. Furthermore, in Japanese Patent Application Laid-Open No. 61-170570,
A technique is described in which a carbon film is formed by plasma discharge using hydrocarbon gas as a raw material, and then heat-treated at 2000°C or higher. However, even this technique was insufficient in terms of conductivity and degree of graphitization. Furthermore, Japanese Patent Publication No. 11325/1983 discloses a technique for co-depositing boron when pyrolytic graphite is vapor-deposited using methane or natural gas; The purpose of this method was to significantly reduce the level of residual stress in the body, but it was not possible to obtain graphite with sufficiently high conductivity. The present invention relates to a method for producing a carbon material in which productivity is improved due to a high deposition rate of a carbon layer, and a carbon material (especially fiber) having higher conductivity and graphitization degree at the same heat treatment temperature as conventional ones. The purpose is to provide a manufacturing method for. [Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. "(1) In a method of manufacturing a carbon layer on a base material,
The main monomer gas is an organic boron compound containing chlorine or a mixed gas consisting of boron trichloride and aromatic hydrocarbons at a temperature of 1000 to 2000°C.
A method for producing a carbon material, characterized by thermal decomposition on a base material at a pressure of 1 to 200 mmHg. (2) In a method for producing a carbon layer on a substrate, an organic boron compound containing chlorine or a mixed gas consisting of boron trichloride and an aromatic hydrocarbon is used as the main monomer gas, at a temperature of 1000 to 2000°C, and a partial pressure of 1 to pyrolyzed onto the substrate at 200 mmHg, then
A method for producing carbon materials characterized by heat treatment at a temperature of 2000°C or higher. In the present invention, the base material may be in any shape such as fiber, molded body, plate, film, or sheet. A particularly preferred base material is carbon fiber. This is because fibrous carbon can be produced when carbon fiber is used as the base material. As carbon fibers, fibers of 10 mm or more are used, and of course continuous fibers are also used. The continuous fibers may be monofilament or multifilament. The carbon fiber may be of any type, such as polyacrylonitrile type or pitch type. Usually, those having a single yarn diameter of about 5 to 20 μm are used. The conductive carbon layer referred to in the present invention is a carbon layer made of a compound whose main component is carbon, in which a structure has been developed in which surfaces composed of six-membered ring carbons bonded by sp ² bonds are bonded by van der Waals bonds. Miller index (002) using X-ray diffraction method
The interplanar spacing obtained from the measurement of the diffraction line shown is
It is a carbon layer consisting of a compound characterized by having a thickness of 3.360 Å or less. In the present invention, first, a chemical vapor deposition method is used as a method for depositing a carbon material containing boron and chlorine on a base material. That is, the carbon layer is deposited by heating the base material while stopping or continuously moving it to thermally decompose the monomer gas on the base material.
Thermal decomposition temperature depends on the monomer gas used, but
-2000°C, preferably 1200-1700°C. Below 1000°C, the carbon layer deposition rate becomes significantly slow. Moreover, if the temperature exceeds 2000°C, thread breakage tends to occur due to abnormally high temperature caused by reaction heat when a fibrous base material is used, which is not preferable. The gas to be thermally decomposed is preferably a gas whose main component is an organic boron compound containing chlorine, or a gas whose main components are boron trichloride and an aromatic hydrocarbon.
When a gas whose main component is an organic boron compound containing chlorine is used, the yield of carbon is improved and the deposition rate is faster than when an organic boron compound consisting only of carbon, hydrogen, and boron is used. This is because not only is the speed increased, but also a carbon material that can be more easily graphitized can be obtained. As the organic compound containing chlorine, ethyl boron dichloride and diethyl boron chloride are more preferable. This is because it has a vapor pressure suitable for use in chemical vapor deposition.
In addition, when using a gas whose main components are boron trichloride and aromatic hydrocarbons as a monomer gas, carbonization is easier than when using an organic boron compound consisting only of carbon, hydrogen, and boron. Materials are obtained. However, the degree of carbonization and conductivity are inferior to those using organic boron compounds containing chlorine. Any aromatic hydrocarbon may be used, but benzene is preferred. In the thermal decomposition of monomer gas, the partial pressure of monomer gas is 1
Perform within the range of ~200mmHg. If the partial pressure exceeds 200mmHg, by-products tend to be generated, and 1mmHg
This is because if the amount is less than that, the deposition rate becomes significantly slow. In particular, when using an organic boron compound containing chlorine, a partial pressure of the organic boron compound is preferably used in a range of 1 to 100 mmHg. More preferably 2
A range of ~30mmHg is good. Thermal decomposition can be carried out in the presence of nitrogen or argon, and if necessary, also in the presence of hydrogen. The thermal decomposition time varies depending on the type of monomer gas used, partial pressure, and thermal decomposition temperature, but is usually about several minutes to several tens of minutes. In order to form a more homogeneous carbon layer, it is preferable to lower the partial pressure of the monomer gas as much as possible within a preferred range and lengthen the thermal decomposition time. The thickness of the carbon layer can be adjusted by controlling the monomer gas partial pressure, thermal decomposition temperature, and thermal decomposition time. In particular, in order to obtain a flexible and highly conductive material using a fibrous base material, the thickness is preferably about 10 to 200 μm. In addition, when providing carbon fiber as a base material in the form of a multifilament, flexibility tends to be lost as the single fibers are bound together by the deposited carbon layer. In order to obtain a carbonaceous material, it is preferable to slow down the layer formation rate as much as possible. The carbon material obtained by the above method can be used as a drum, prepreg, heat-resistant plate, etc. The carbon layer-covered carbon material obtained by the above method is then heat-treated to obtain a carbon material having a highly conductive carbon layer. The heat treatment temperature at this time is preferably 2000°C or higher and 2900°C or lower. More preferably 2300
~2700℃ is good. The heat treatment time is preferably 5 to 60 minutes. It is also possible to intercalate an electron-donating or electron-accepting substance into the carbon material obtained by the above method in order to obtain a material with higher conductivity. The method is described, for example, in "Carbon", published by the Carbon Materials Society, vol. 111, p. 171 (1982).
It is described in. Examples of electron-donating or electron-accepting substances include alkali metals such as potassium and cesium, halogen gases such as chlorine and bromine,
Halogen compounds such as ICl, metal halides such as CuCl ₂ and FeCl ₂ , acids such as nitric acid, sulfuric acid, and AsF ₅ , and intermetallic compounds such as alkali metal-mercury and mercury-bismuth are used, but they are inexpensive. , and nitric acid is most preferred since the product is stable. By the production method according to the present invention described above, a carbon material containing boron and chlorine and a highly conductive carbon material can be obtained. [Example] Comparative Example 1 Carbon fiber (Thornel-P75, manufactured by UCC, USA) was attached to a fixed electrode, and triethylboron was heated at a partial pressure of 3 mmHg under reduced pressure to 1350°C.
A carbon layer was deposited on the carbon fibers. Ten
The diameter of the fibers obtained with a reaction time of minutes was 50 μm. Example 1 Carbon fiber (Thornel-P75, manufactured by UCC, USA) was attached to a fixed electrode, and diethyl boron chloride was heated at a partial pressure of 3 while heating with electricity to 1350°C under reduced pressure.
mmHg was introduced and a carbon layer was deposited on the carbon fiber. The diameter of the fiber obtained with a reaction time of 10 minutes is
It was 60 μm. Example 2 In the same manner as in Example 1, ethyl boron dichloride was introduced at a partial pressure of 3 mmHg to deposit a carbon layer on the carbon fibers. The diameter of the fibers obtained with a reaction time of 10 minutes was 65 μm. Comparative Example 2 Base material carbon fiber (Thornel, manufactured by UCC, USA)
−P75) in an argon atmosphere with a diameter of 15 mm and a total length of 45 cm.
Two metal rollers were used to run continuously through a quartz reaction tube, and while heating the benzene with electricity to 1500°C through the rollers, the benzene was heated at a partial pressure of 10 mmHg.
and a carbon layer was deposited on the carbon fibers. The fibers thus obtained were heated at 2500 °C in an argon stream.
Heat treatment was performed at ℃ for 30 minutes. The diameter of the obtained fibers was 90 μm. When the electrical conductivity at room temperature was measured by the DC four-terminal method, it was 1.6×10 ³ S/cm. Comparative Example 3 After depositing a carbon layer in the same manner as in Comparative Example 2, the fibers were heat-treated at 2700°C for 30 minutes in an argon stream, and the conductivity at room temperature of the resulting fiber was measured to be 2.1×10 ³ It was S/cm. Comparative Example 4 Base material carbon fiber (Thornel, manufactured by UCC, USA)
−P75) in an argon atmosphere with a diameter of 15 mm and a total length of 45 cm.
Two metal rollers were used to run continuously through a quartz reaction tube, and triethylboron was heated at a partial pressure of 3 mm while being electrically heated to 1350°C by the rollers.
Hg was introduced and a boron-containing carbon layer was deposited on the carbon fiber. The fibers thus obtained were heat treated at 2500°C for 30 minutes in an argon stream.
The diameter of the obtained fibers was 100 μm. When the electrical conductivity was measured at room temperature using the DC four-terminal method,
It was 3.1×10 ³ S/cm. Comparative Example 5 After depositing a carbon layer in the same manner as in Comparative Example 4, the fibers were heat-treated at 3000°C for 30 minutes in an argon stream, and the conductivity at room temperature of the resulting fiber was measured to be 4.9×10 ³ It was S/cm. Example 3 Carbon fiber as a base material (Thornel, manufactured by UCC, USA)
−P75) in an argon atmosphere with a diameter of 15 mm and a total length of 45 cm.
Diethyl boron chloride was introduced at a partial pressure of 3 mmHg through two metal rollers that were continuously run through the quartz reaction tube, and heated to 1350°C through the rollers. A carbon layer was deposited on the carbon fiber. The fibers thus obtained were heat treated at 2500°C for 30 minutes in an argon stream. The diameter of the resulting fiber is
It was 120 μm. When the electrical conductivity at room temperature was measured by the DC four-terminal method, it was 6.5×10 ³ S/cm. Fibers obtained in Comparative Example 2 or Comparative Example 5 with a heat treatment temperature of 2500°C, fibers obtained in Comparative Example 5 with a heat treatment temperature of 2700°C, and fibers obtained in Comparative Example 5 with a heat treatment temperature of 3000°C. It has a higher electrical conductivity than fibers. Example 4 In the same manner as in Example 3, ethyl boron dichloride was introduced at a partial pressure of 3 mmHg to deposit a carbon layer containing boron and chlorine on the carbon fibers. The fibers thus obtained were heat treated at 2500°C for 30 minutes in an argon stream. The diameter of the resulting fiber is
It was 130 μm. When the electrical conductivity at room temperature was measured by the DC four-terminal method, it was 7.5×10 ³ S/cm. Example 5 In the same manner as in Example 3, a mixed gas consisting of benzene at a partial pressure of 10 mmHg and boron trichloride at a partial pressure of 10 mmHg was introduced to deposit a carbon layer containing boron and chlorine on the carbon fiber. The fibers thus obtained were heat treated at 2500°C for 30 minutes in an argon stream. The diameter of the obtained fibers was 60 μm. When the electrical conductivity at room temperature was measured by the DC four-terminal method, it was 5.0×10 ³ S/cm. Example 6 The carbon fibers obtained in Comparative Example 2, Comparative Example 4, and Example 4 were subjected to X-ray diffraction using Cu-Kα rays using a wide-angle X-ray diffractometer manufactured by Rigaku Denki Co., Ltd. Measured by transmission method. The results are shown in FIG. In FIG. 1, a represents the result obtained in Comparative Example 2, b represents the result obtained in Comparative Example 4,
c indicates the carbon fiber obtained in Example 4. Further, Table 1 shows the interlayer spacing obtained from the (002) diffraction line position, and Table 2 shows the crystallite size (c-axis direction) obtained from the (002) diffraction line width.

【table】

[Table] As shown, it can be seen that the highly conductive carbon fiber according to the present invention has a small interlayer spacing, a large crystallite size, and a high degree of graphitization. Example 7 The carbon fibers obtained in Comparative Example 2, Comparative Example 4, and Examples 3, 4, and 5 were manufactured by Jobin-
Using a Yvon laser Raman microprobe, we measured the Raman spectrum of the side of the fiber from 1200 to 1200.
Measured in a range of 1800 cm ^-1 . The results are shown in FIG. In FIG. 2, a indicates the carbon fiber obtained in Comparative Example 2 (using benzene as a monomer and heat-treated at 2500° C.). b is the carbon fiber obtained in Comparative Example 5 (triethyl boron is used as a monomer and heat treated at 2500°C)
shows. c indicates the carbon fiber obtained in Example 3 (using diethyl boron chloride as a monomer and heat-treated at 2500°C). d indicates the carbon fiber obtained in Example 4 (using ethyl boron dichloride as a monomer and heat-treated at 2500°C). e is the carbon fiber obtained in Example 5 (the monomer is a mixed gas consisting of benzene and boron trichloride,
heat treated at 2500℃). Literature (F.Tuinstra & JLKoenig, J.
Chem.Physics53(3)1126(1870). ), 1590
Peak A at cm ^-1 is assigned to graphite, and peak B at 1370 cm ^-1 is assigned to amorphous carbon. Therefore, the smaller the intensity ratio IB/IA between the intensity IA of peak A and the intensity IB of peak B, and the narrower the half-width of peak A, the higher the degree of graphitization. Table 3 shows the intensity ratio IB/IA obtained from Raman spectroscopy of the carbon fibers obtained in Comparative Examples 2 and 4 and Examples 3, 4, and 5, and Table 4 shows the half-value width of peak A.

【table】

[Table] Thus, it can be seen that the highly conductive carbon fiber according to the present invention has a high degree of graphitization. [Effects of the Invention] The present invention provides a method for producing a carbon material with improved productivity due to an improvement in the deposition rate of the carbon layer, and a method for producing a carbon material (especially fiber) having high conductivity and a degree of graphitization. can be provided.

[Brief explanation of drawings]

FIG. 1 shows the results of X-ray diffraction measurements using Cu-Kα rays of various carbon fibers using a wide-angle X-ray diffractometer manufactured by Rigaku Denki Co., Ltd. using a transmission method. A shows the spectrum of the carbon fiber obtained in Comparative Example 2, b shows the spectrum of Comparative Example 4, and c shows the spectrum of each carbon fiber obtained in Example 4. Figure 2 shows various types of carbon fibers being processed using a laser Raman microprobe manufactured by Jobin-Yvon, France.
The results of measuring the Raman spectrum of the side surface of the fiber in the range of 1200 to 1800 cm ^-1 are shown. The spectra of the carbon fibers obtained in a are Comparative Example 2, b are Comparative Example 4, c are Example 3, d are Example 4, and e are Example 5.

Claims (1)

[Claims] 1. A method for producing a carbon layer on a substrate, using an organic boron compound containing chlorine or a mixed gas consisting of boron trichloride and an aromatic hydrocarbon as the main monomer gas, at a temperature of 1000 to 2000°C, Pressure 1~
A method for producing carbon materials characterized by pyrolysis on a substrate at 200 mmHg. 2. The method for producing a carbon material according to claim 1, wherein the organic boron compound containing chlorine is at least one selected from ethyl boron dichloride and diethyl boron chloride. 3. The method for producing a carbon material according to claim 1, wherein the pressure is 1 to 100 mmHg. 4. The method for producing a carbon material according to claim 1, wherein the aromatic hydrocarbon is benzene. 5. The method for producing a carbon material according to claim 1, wherein the base material is carbon fiber. 6 In a method for producing a carbon layer on a substrate, an organic boron compound containing chlorine or a mixed gas consisting of boron trichloride and an aromatic hydrocarbon is used as the main monomer gas at a temperature of 1000 to 2000°C and a pressure of 1 to
A method for producing a carbon material, characterized by pyrolysis on a base material at 200 mmHg, and then heat treatment at a temperature of 2000°C or higher. 7. The method for producing a carbon material according to claim 6, wherein the organic boron compound containing chlorine is at least one selected from ethyl boron dichloride and diethyl boron chloride. 8. The method for producing a carbon material according to claim 6, wherein the pressure is 1 to 100 mmHg. 9. The method for producing a carbon material according to claim 6, wherein the aromatic hydrocarbon is benzene. 10. The method for producing a carbon material according to claim 6, wherein the base material is carbon fiber. 11. The method for producing a carbon material according to claim 6, wherein the heat treatment is performed at 2300 to 2800°C.