JPH01272827A - Method for carrying out continuous graphitization treatment and apparatus therefor - Google Patents

Abstract

PURPOSE:To obtain a graphite whisker, by continuously and intermittently passing a carbonaceous fiber packed in a heat resistant vessel into a high- temperature area and subjecting a vapor growth carbon fiber having substantially powdery form to graphitization treatment. CONSTITUTION:A vapor growth carbon fiber is packed into a container 10 made of graphite and carried into an inert gas-replacing front chamber and degassed through a gas valve 22 and an inert gas is charged therein. The container 10 carried into a chamber 30 for work fixing is supported with a supporter 32 for fixing and successively transferred into a chamber 34 for graphitization treatment, passed into an effective heating area 36 and transferred through a carrying chamber 40 and preliminary chamber 44 into an inert gas- replacing rear chamber 50. The chamber 50 is degassed through a gas valve 52 and an inert gas is charged therein to replace the vapor in the chamber by the inert gas and the container 10 is carried into a conveyor and a graphite whisker being contents of the container is taken out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to graphitization treatment of carbon fibers, and more particularly, to continuous graphitization treatment of vapor-grown carbon fibers that are substantially in the form of powder. The present invention relates to a method and apparatus for producing graphite whiskers.

[Conventional technology]

Carbon lIi navy blue is a type of fibrous material that is mostly composed of carbon element, and is grown as a single crystal from the gas phase by growing a single crystal in a carbon arc under high pressure inert gas or by pyrolysis of hydrocarbon gas. It is produced by growing organic Il fibers or by carbonizing organic Il fibers. The most widely used method is carbonization of I1m miscellaneous materials, and the starting materials used include cellulose fibers, rayon fibers, acrylonitrile-based II miscellaneous materials, and the like. When these are heated to a temperature of about 800° C. in the absence of air and moisture, carbon fibers are formed, and when these are further heated to about 3000° C., graphite fibers are formed. Carbon fibers and graphite fibers have extremely high strength and stiffness, making them useful for example in composite materials.
) is used as a plastic resin reinforcing agent in making.

The constituent carbon atoms in the carbon fiber exist as graphite-type hexagonal hexagonal plate-shaped flat crystals, and six carbon rings are connected to form a layered structure. When carbon fibers are further heated to form graphite fibers, this basic layered structure remains the same, but the distance between the layers, that is, the interplanar spacing, becomes smaller.
It becomes a more detailed structure. For example, vapor grown carbon fiber (V
apor Growth Carbon Fiber,
VGCF) has a lattice spacing of 3.48 people, but when this is subjected to graphitization treatment, the lattice spacing becomes 3.354 people.

Generally, if the interplanar spacing is 3.36 Å or less, it can be considered to be essentially graphite, but the degree of graphitization reflected in this interplanar spacing is only correlated with the processing temperature if graphitization treatment is carried out for a certain period of time. do. In other words, if we consider the degree of graphitization as a function of treatment time, the degree of graphitization will increase with time from the start of treatment, but after a certain period of time it will reach a saturation value, and the degree of graphitization will continue to increase even after a certain amount of time has elapsed. does not change, and the saturation value at this time is defined only by the processing temperature. As the processing temperature is increased, the spacing at the time when the saturation value is reached decreases, for example, at 2000°C, 2500°C, and 3000°C, it becomes 3.42 people, 3.37 people, and 3.36 people, respectively.

Since the time required to reach the saturation value is usually several minutes, maintaining the carbon tan at a given temperature for several minutes is sufficient to obtain graphitized fibers with the desired degree of graphitization.

In conventional batch-type graphitization processing, it takes about 3 hours from the start of operation to reach the processing temperature of around 3000°C, and after processing for several minutes at the practically required temperature, it takes about 6 hours again to reach the processing temperature of around 3000 ° C. Since graphitization was performed after the temperature was returned to room temperature, the temperature raising and cooling steps required a large amount of time and were extremely inefficient. In order to eliminate these drawbacks, various methods and apparatuses have been devised for continuously graphitizing fibrous carbon fibers. Since the fiber-shaped material has a continuous long linear structure, it is relatively easy to achieve continuous processing. However, it is not possible to carry out continuous graphitization of carbon fiber whiskers with a length of about 2 to 2000 meters or materials that are substantially in the form of powder, such as VGCF, using the same concept as continuous graphitization of fibrous materials. Can not.

Graphite whiskers are materials with extremely high strength and rigidity that can be used to manufacture graphite whisker-reinforced plastic composite materials, and it is desired to realize a method and apparatus for efficiently manufacturing them from vapor-grown carbon fibers. .

[Problem to be solved by the invention]

An object of the present invention is to provide a method and apparatus for producing graphite whiskers by continuously and efficiently graphitizing vapor-grown carbon fibers that are substantially in the form of powder.

[Means to solve the problem]

According to the present invention, there is provided a continuous graphitization treatment method characterized by passing carbonaceous fibers filled in a heat-resistant container continuously or intermittently through a high-temperature zone.

It is preferable that the carbonaceous fiber is vapor grown fiber (VGCF), PAN-based carbon 1iAM, rayon-based carbon fiber, or pitch-based carbon fiber, and it is preferable that the high-temperature zone is an inert gas atmosphere. It is suitable if it is 1500 degreeC - 3500 degreeC, and it is suitable if the heat-resistant container is a container made from graphite.

Furthermore, according to the present invention, when producing graphite whiskers by continuously graphitizing vapor-grown carbon fibers substantially in the form of powder, a hollow cylindrical graphite container is filled with vapor-grown carbon fibers. Then, 41 tons of vapor-grown carbon was added to the chamber before inert gas replacement.
A hollow cylindrical graphite container filled with I# is brought in, the air is removed and the pre-inert gas replacement chamber is made substantially evacuated, and then an inert gas is introduced to replace the gas phase with the inert gas. , a graphitization method in which a plurality of hollow cylindrical graphite containers filled with vapor-grown carbon fibers are heated and maintained at a temperature that allows graphitization treatment in an inert gas atmosphere. Hollow cylindrical graphite containers filled with vapor-grown carbon fibers are brought in one after another intermittently at predetermined time intervals from the entrance of the processing chamber, and the graphitization process is performed to convert the vapor-grown carbon fibers into graphite whiskers and graphitize them. A hollow cylindrical graphite container filled with graphite whiskers, which is carried out from the graphitization processing chamber outlet at the same time as the transport to the processing chamber entrance, is carried into the chamber after inert gas replacement under an inert gas atmosphere. The graphite whiskers are removed from the container after the hollow cylindrical graphite container filled with graphite whiskers is removed from the inert gas purging chamber into which an inert gas can be introduced after the interior is evacuated. A method for continuously graphitizing vapor grown carbon fibers is provided.

Further, according to the present invention, there is provided an apparatus for producing graphite whiskers by continuously graphitizing vapor-grown carbon fibers substantially in the form of powder, the apparatus comprising a plurality of hollow spaces filled with vapor-grown carbon fibers. a filling means consisting of a cylindrical graphite container; a carrying means for transporting the hollow cylindrical graphite container filled with vapor-grown carbon fibers into an inert gas replacement chamber where inert gas replacement is performed;
A hollow cylindrical graphite container is housed at the entrance of a graphitization processing chamber under an inert gas atmosphere, and is equipped with a vacuum means capable of removing air and creating a vacuum inside, and an inert gas introduction means capable of introducing an inert gas. A hollow cylindrical graphite container filled with vapor-grown carbon fibers is intermittently transferred from the inert gas preplacement chamber to the graphitization treatment chamber at predetermined time intervals. A carrying means for successively carrying the materials into the chamber, a vibrator-shaped graphitization processing chamber in which a plurality of hollow cylindrical graphite containers filled with vapor-grown carbon fibers can slide, and a heating means for heating the graphitization processing chamber. and a maintenance means for maintaining the graphitization chamber under an inert gas atmosphere, and a graphitization treatment means for converting vapor-grown carbon III into graphite whiskers;
The hollow cylindrical graphite container filled with graphite whiskers, which is carried out from the graphitization processing chamber outlet at the same time as the transport to the graphitization processing chamber entrance, is transported to the inert gas replacement chamber where inert gas replacement is performed. A hollow cylindrical graphite comprising a conveyance means, a vacuum means which is located at the outlet of a graphitization processing chamber under an inert gas atmosphere and can remove air to create a vacuum inside, and an inert gas introduction means which can introduce an inert gas. The present invention is characterized by comprising an inert gas replacement means consisting of an inert gas replacement chamber for storing the manufactured container, and a transport means for transporting the hollow cylindrical graphite container filled with graphite whiskers from the inert gas replacement chamber. A continuous graphitization treatment apparatus for vapor-grown carbon fiber is provided.

[Effect]

Carbon with the continuous graphitization treatment of the present invention! The graphitization chamber, where IH is graphitized and converted into graphite fibers, is heated by an appropriate heating means and maintained at a predetermined temperature, but the temperature distribution within the graphitization chamber is highest near the center of the chamber. The temperature gradually decreases from the maximum temperature near the center as it approaches the inlet and outlet of the processing chamber. As mentioned above, in order to obtain the desired degree of graphitization, it is sufficient to maintain the carbon fiber for several minutes at the necessary treatment temperature, which is uniquely determined in correlation to the degree of graphitization. Graphite whiskers with the desired degree of graphitization can be obtained by maintaining the vicinity of the central portion at a necessary processing temperature and allowing the vapor-grown carbon fibers to remain in this portion for several minutes. A hollow cylindrical graphite container is filled with vapor-grown carbon fibers, and the hollow cylindrical graphite container is placed in a vibrator-shaped graphitization chamber that can slide inside. When hollow cylindrical graphite containers filled with miscellaneous materials are transported one after another at predetermined time intervals, the time intervals between the transports are set so that the hollow cylindrical graphite containers filled with vapor-grown carbon fibers achieve the desired degree of graphitization. By setting the graphitization chamber to remain for at least several minutes near the center of the processing chamber, which is maintained at the processing temperature required for Carbon I! Various continuous graphitization treatments can be performed.

〔Example〕

The present invention will be described in more detail below with reference to the accompanying drawings, but the present invention is not limited only to the following examples.

FIG. 1 shows a vertical cross-sectional view of essential parts of a continuous graphitization treatment apparatus constructed according to the present invention. In FIG. 1, 10 is a hollow cylindrical graphite container, 12 is a carry-in arm, 14 is a carry-in cylinder, 16 is a valve cylinder, 18 is an inert gas exchange front chamber, 20 is a stepping motor, 22 is a gas valve, 24
is a linear motor, 26 is a gate valve, 28 is a gas valve, 30 is a workpiece fixing chamber, 32 is a fixing support, 34 is a graphitization processing chamber, 36 is an effective heating zone, 38 is a gas valve, 40 is a transfer chamber, 42 is a gate valve,
44 is a preliminary chamber, 46 is a clamp cylinder, 48
50 is a gate valve, 50 is an inert gas replacement chamber, 52 is a gas valve, 54 is a valve cylinder, 56 is an unloading cylinder,
58 is a carry-out arm, and 60 is a conveyor.

Vapor grown carbon! Hollow cylindrical graphite container filled with miscellaneous materials 1
0 with the rotary carry-in arm 12 and move it to the inert gas replacement front chamber 1.
8 and carried into the inert gas pre-substitution chamber 18 by a vertically moving carrying means driven by a carrying cylinder 14, and the sealing valve is moved by the valve cylinder 16 before inert gas substitution. The entry opening of chamber 18 is sealed. As graphite container support and movement means provided in the inert gas replacement chamber 18, for example, a rotary disk 62 rotated by a stepping motor 20 is provided, and a plurality of graphite containers are supported on the rotary disk and rotated by a predetermined angle. It is preferable to move it. The inert gas replacement front chamber 18 has a gate valve 2
6 is closed, the gas is degassed through the gas valve 22 to create a vacuum, and then an inert gas such as nitrogen is introduced to replace the gas phase with the inert gas.

The graphite container that has been moved to a predetermined position is transported to the workpiece fixing chamber 30 at predetermined time intervals using vertical movement means driven by the linear motor 24 and timed to the opening and closing of the gate valve 26 . The graphite containers are supported by a fixing support 32 provided in the workpiece fixing chamber 30 to ensure that the containers filled with carbon fibers are sequentially transferred to the graphitization processing chamber 34. The graphitization processing chamber 34 has a vibe-like shape in which the hollow cylindrical graphite container 10 can slide,
For example, by heating with a high frequency coil, an effective heating zone 36 whose temperature is set to a desired degree of graphitization is formed near the center thereof. The time interval between the introduction of the graphite containers is adjusted so that the residence time of the containers in the effective heating zone is sufficient to effect graphitization at the set temperature, which is usually around 5 minutes.

Graphite containers were transported to the graphitized Miyahito [1].
It is carried out from the outlet of the graphitization processing chamber in a sequential manner and transferred to the conveyance chamber t.
<, Move to 40. Note that the workpiece fixing chamber 30, the graphitization processing chamber 34, and the transfer chamber 40 are maintained under an inert gas atmosphere via gas valves 28 and 38.

The container filled with graphite mi resulting from the graphitization process is passed through the gate valve 42 to the preliminary chamber 44 by a vertical moving means driven by the clamping cylinder 46, and then transferred to the inert gas post-substitution chamber 50. The inert gas post-substitution chamber 50 is opened by closing the gate valve 48 and moving the valve using the valve cylinder 54.
The outlet section of the graphite container is opened, and the graphite container is moved to a predetermined position by vertical moving means driven by the unloading cylinder 56.

It is grabbed by the carry-out arm 58 and moved to the conveyor 60. The valve is moved by the valve cylinder 54 to seal the discharge outlet, and the gas is degassed through the gas valve 52, and after creating a vacuum, an inert gas is introduced to replace the gas phase with the inert gas. Graphite whiskers are obtained by removing the contents of the graphite container carried by the conveyor 60. Examples are shown in Table 1 below.

Table 1 black place [ place [ surface [ place [ The container was filled with 30g of VGCF.

As a comparative example, Table 2 shows a comparative example in which a patch system was subjected to graphitization treatment.

Table 2 [Effects of the Invention] According to the present invention, vapor-grown carbon fibers substantially in the form of powder are continuously and efficiently graphitized to stably produce graphite whiskers with a desired degree of graphitization. can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a main part of a continuous graphitization treatment apparatus constructed according to the present invention. 10...Hollow cylindrical graphite container 12...Carry-in arm 14...Carry-in cylinder 1
6...Valve cylinder 18...Inert gas replacement chamber 20...Stepping motor 22...Gas valve 24...Linear motor 2
6...Gate valve 28...Gas valve 30.
... Workpiece fixing chamber 32... Fixing support 34... Graphitization processing chamber 3
6... Effective heating zone 38... Gas valve 40.
・・Transport chamber 42・・Goo 1~Valve 44・
・Preliminary chamber 46 ・Clamp cylinder 48 ・Gate valve 50 ・Chamber after inert gas replacement

Claims (7)

[Claims] (1) A continuous graphitization method characterized by passing carbonaceous fibers filled in a heat-resistant container continuously or intermittently through a high-temperature zone. (2) Carbon fiber is vapor grown carbon fiber (VGCF) PA
2. The continuous graphitization method according to claim 1, wherein the carbon fiber is N-based carbon fiber, rayon-based carbon fiber, or pitch-based carbon fiber. (3) The continuous graphitization method according to claim 1, wherein the high temperature zone is an inert gas atmosphere. (4) The continuous graphitization treatment method according to claim 1, wherein the high temperature zone is 1500°C to 3500°C. (5) The continuous graphitization method according to claim 1, wherein the heat-resistant container is a graphite container. (6) When manufacturing graphite whiskers by continuously graphitizing vapor-grown carbon fibers that are substantially in the form of powder, the vapor-grown carbon fibers are filled into a hollow cylindrical graphite container, and the vapor-grown carbon fibers are inert. A hollow cylindrical graphite container filled with vapor-grown carbon fibers is carried into the pre-gas replacement chamber, the air is removed to make the inert gas pre-replacement chamber substantially evacuated, and then an inert gas is introduced and the gas is removed. The phase is replaced with an inert gas, and the container has a pipe-like shape in which a plurality of hollow cylindrical graphite containers filled with vapor-grown carbon fibers can slide, and graphitization treatment can be performed in an inert gas atmosphere. Hollow cylindrical graphite containers filled with vapor-grown carbon fibers are brought in one after another intermittently at predetermined time intervals from the entrance of the graphitization chamber heated and maintained at a certain temperature, and the graphitization process is carried out to convert the vapor-grown carbon fibers into graphite. The hollow cylindrical graphite container filled with graphite whiskers, which are converted into whiskers and carried out from the graphitization processing chamber outlet at the same time as the transport to the graphitization processing chamber entrance, is replaced with inert gas under an inert gas atmosphere. Graphite is removed from the container after the hollow cylindrical graphite container filled with graphite whiskers is transported into the rear chamber and the hollow cylindrical graphite container filled with graphite whiskers is removed from the inert gas replacement chamber. A method for continuous graphitization of vapor-grown carbon fiber, characterized by removing whiskers. (7) An apparatus for producing graphite whiskers by continuously graphitizing vapor-grown carbon fibers substantially in the form of powder, the device being made of a plurality of hollow cylinders of graphite filled with vapor-grown carbon fibers. A filling means consisting of a container, a carrying means for transporting the hollow cylindrical graphite container filled with vapor-grown carbon fibers into an inert gas replacement chamber where inert gas replacement is performed, and graphitization treatment under an inert gas atmosphere. It consists of an inert gas replacement front chamber that houses a hollow cylindrical graphite container, which is equipped with a vacuum means that is located at the entrance of the chamber and can remove air to create a vacuum inside, and an inert gas introduction means that can introduce an inert gas. an inert gas replacement means, and a transport means for intermittently transporting hollow cylindrical graphite containers filled with vapor-grown carbon fibers from the inert gas pre-replacement chamber to the graphitization processing chamber one after another at predetermined time intervals; A pipe-shaped graphitization processing chamber in which a plurality of hollow cylindrical graphite containers filled with vapor-grown carbon fibers can slide, a heating means for heating the graphitization processing chamber, and an inert gas a graphitization treatment means for converting the vapor-grown carbon fiber into graphite whiskers, which is comprised of a maintenance means for maintaining the vapor-grown carbon fibers in an atmosphere; and graphitization treatment means, which is carried out from the graphitization treatment chamber outlet at the same time as the graphitization treatment chamber is delivered to the graphitization treatment chamber entrance. A transport means for transporting a hollow cylindrical graphite container filled with whiskers to a post-inert gas replacement chamber for inert gas replacement, and a transport means for removing air at the outlet of the graphitization processing chamber under an inert gas atmosphere. An inert gas replacement means comprising an inert gas replacement chamber for housing a hollow cylindrical graphite container, which is equipped with a vacuum means capable of creating a vacuum inside and an inert gas introduction means capable of introducing an inert gas; 1. An apparatus for continuous graphitization of vapor-grown carbon fibers, comprising a carrying means for carrying out a hollow cylindrical graphite container filled with graphite whiskers from a post-substitution chamber.