JPH07166431A - Production of carbon fiber grown in gas phase - Google Patents

Abstract

PURPOSE:To provide a process for efficiently producing a high-quality carbon fiber grown in a gas phase on an industrial scale at a low cost, in a high yield and in a short time. CONSTITUTION:This process for producing a carbon fiber grown in a gas phase comprises the first process in which a carbon compound-containing feeding material for producing a raw fiber and a metal compound are heated and the second process in which the raw fiber and a feeding material for the growth of a raw fiber, containing at least one kind selected from a group consisting of polycyclic aromatic hydrocarbon compounds and their derivatives are subjected to a heating treatment.

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 vapor-grown carbon fiber, and more particularly to a vapor-grown carbon fiber capable of producing a high-quality, vapor-grown carbon fiber with high yield and in a short time. The present invention relates to a method for producing a phase-grown carbon fiber.

[0002]

2. Description of the Related Art Vapor-grown carbon fibers are a special type of carbon fiber having a structure in which a condensed annular carbon surface is parallel to the fiber axis and has a ring-shaped structure centered on the fiber axis. It is a continuous fiber and has excellent properties such as high mechanical strength and high elasticity. Therefore, by compounding this with various matrix materials such as plastics, ceramics, rubber, and metals, composite materials suitable for a wide range of fields including materials for space aircraft, electronic / electrical materials, sports / leisure related materials, etc. In recent years, research and development for obtaining syrup have been actively conducted.

As a method for producing such a vapor-grown carbon fiber, for example, a method for efficiently producing a large amount of vapor-grown carbon fiber by reacting a metal compound as a catalyst with a hydrocarbon at a high temperature. It has been known. However, since the vapor grown carbon fiber obtained by the above method is a fine elementary fiber, it is necessary to further grow the elementary fiber in order to obtain a vapor grown carbon fiber having a sufficient size.

As a method for producing a vapor-grown carbon fiber having a practically sufficient size, conventionally, for example, a first fiber is produced in a first step, and a second fiber is grown in a thickness in a second step. A stepwise method has been proposed.

However, in the second step, in order to improve the thickness growth rate, a method of increasing the concentration of organic carbon serving as a carbon source and the reaction temperature can be considered. In this case, the vapor-grown carbon fiber obtained is obtained. There is a problem that soot is generated, and high-quality vapor-grown carbon fibers cannot be manufactured. Therefore, at present, a method for efficiently producing a vapor-grown carbon fiber having a sufficient size and high quality is not provided.

The present invention solves the above-mentioned problems, and is capable of producing a high-quality vapor-grown carbon fiber having a high yield, a high efficiency, and a sufficient size in a short time, which is industrially advantageous. It is an object of the present invention to provide a method for producing grown carbon fiber.

[0007]

As a result of intensive investigations by the present inventors in order to solve the above-mentioned problems, the present invention shows that, when a specific raw material is used for growing an elementary fiber, only a thickness growth rate is obtained. It has been found that the carbon yield can be improved without any problem, and high-quality vapor-grown carbon fibers having a sufficient size can be efficiently produced in a short time.

That is, according to the present invention, a first step of heating a raw material for producing a fiber containing a carbon compound and a metal compound to produce a fiber, a fiber produced in the first step and a polycyclic system A second step of heating at least one selected from the group consisting of aromatic hydrocarbon compounds and derivatives thereof to grow elementary fibers in the thickness direction, a method for producing vapor-grown carbon fibers, Is.

More specific embodiments of the present invention will be listed below.

A first aspect of the present invention comprises a first step of producing a raw fiber by heating a raw material for producing a raw fiber containing a carbon compound excluding a polycyclic aromatic hydrocarbon compound and a metal compound, There is a second step of heating the elemental fibers produced in this first step and at least one selected from the group consisting of polycyclic aromatic hydrocarbon compounds and their derivatives to grow the elemental fibers in the thickness direction. A second aspect of the present invention is the method for producing a vapor-grown carbon fiber, wherein the carbon compound used in the first step is a saturated aliphatic compound in the claim 1 or the first aspect. Selected from the group consisting of hydrocarbons, unsaturated aliphatic hydrocarbons, aromatic hydrocarbons (excluding polycyclic aromatic hydrocarbons), cyclic hydrocarbons, carbon monoxide and carbon dioxide. Be at least one A method for producing a vapor-grown carbon fibers, wherein, the third aspect of the invention, claim 1,
In any of the first and second aspects,
A carbon compound used in the first step is an aromatic hydrocarbon (however, excluding polycyclic aromatic hydrocarbons), which is a method for producing a vapor-grown carbon fiber. A fourth aspect is the carbon compound used in the first step according to any one of claims 1 and 1 to 3, wherein the carbon compound is at least one selected from the group consisting of benzene, toluene and xylene. It is a method for producing a vapor-grown carbon fiber, which is characterized by:
Of the vapor-grown carbon fiber according to any one of claims 1 and 1 to 4, wherein the carbon compound is subjected to a reaction with a carrier gas in the first step. A sixth aspect of the present invention is characterized in that, in any one of the first aspect and the first to fifth aspects, the metal compound used in the first step is a metallocene. A seventh aspect of the present invention is a method for producing a vapor-grown carbon fiber, wherein the metal compound used in the first step is an organic compound in any one of the first aspect and the first to sixth aspects. At least one selected from the group consisting of metal compounds, metal sulfur compounds and inorganic metal compounds, preferably organic metal compounds, and more preferably metallocene, vapor-grown carbon fibers. A method of manufacturing, the eighth of the present invention
The metal compound in the first step has a concentration of the metal compound relative to the carbon compound of 0.1 to 10 in the first step and the first to seventh modes.
A method for producing a vapor-grown carbon fiber, characterized in that the content is mol%, preferably 0.5 to 3 mol%, and a ninth aspect of the present invention is the method according to claim 1 and the first to eighth aspects. In any of the above aspects, when the carbon compound is subjected to the reaction with a carrier gas in the first step,
The concentration of the carbon compound with respect to the carrier gas is 3
It is a manufacturing method of the vapor growth carbon fiber characterized by being -30 mol%, preferably 5-10 mol%, and the 10th aspect of this invention is said claim 1 and said 1st-9th. In any one of the above modes, the heating temperature range is 500 to 1,300 ° C., preferably 1,05 as the condition for heating the raw material for forming the fiber and the metal compound in the first step.
0 to 1,200 ° C., heating time is 0.1 to 60 minutes,
The method for producing a vapor-grown carbon fiber is preferably 1 to 10 minutes, and an eleventh aspect of the present invention is the method according to any one of the first aspect and the first to tenth aspects. And a method for producing a vapor-grown carbon fiber, wherein at least one selected from the group consisting of polycyclic aromatic hydrocarbon compounds and derivatives thereof in the second step is provided together with a carrier gas. A twelfth aspect of the invention is, in any one of the above-described claim 1 and the first to eleventh aspects, the polycyclic aromatic hydrocarbon compound is naphthalene, phenanthrene, anthracene, pyrene, naphthacene, chrysene, picene, tetralin, A compound characterized by being at least one selected from the group consisting of triphenylene, perylene, benzopyrene, coronene and ovalen. A thirteenth aspect of the present invention is a method for producing a grown carbon fiber, wherein the polycyclic aromatic hydrocarbon compound is naphthalene, phenanthrene, or anthracene according to any one of the first to eleventh aspects. And at least one selected from the group consisting of these derivatives, which is a method for producing a vapor-grown carbon fiber, wherein a fourteenth aspect of the present invention is the method according to claim 1 and the first to the first. In any one of the thirteenth aspect, in the second step, the raw material for thickness growth, which is at least one selected from the group consisting of the elementary fiber obtained in the first step, a polycyclic aromatic hydrocarbon compound, and a derivative thereof. A method for producing a vapor-grown carbon fiber, which comprises heating a raw material gas obtained by gasifying an organic solvent solution containing carbon and a raw fiber, which is a fifteenth aspect of the present invention. In the fourteenth aspect, the concentration of at least one selected from the group consisting of polycyclic aromatic hydrocarbon compounds and derivatives thereof in the organic solvent solution is 1 to 80 mol%, preferably 10 to 80 mol%. And more preferably 50 to 80 mol%, a method for producing a vapor-grown carbon fiber, wherein the 16th aspect of the present invention relates to the 14th and 1st aspects.
5 is a method for producing a vapor-grown carbon fiber, characterized in that the source gas is supplied together with a carrier gas. The 17th aspect of the present invention is the method according to the 16th aspect, The concentration of at least one selected from the group consisting of polycyclic aromatic hydrocarbon compounds and their derivatives relative to the carrier gas is 0.5 to 30 mol%, preferably 1 to 10 mol%, more preferably 1 to 10 mol%. , Particularly preferably 3 to 5 mol%, a method for producing a vapor-grown carbon fiber, which is the first aspect of the present invention.
Aspect 8 is the condition for heating the elementary fibers and at least one selected from the group consisting of polycyclic aromatic hydrocarbon compounds and derivatives thereof in the aspect of any one of claims 1 and 1 to 17. As the heating temperature is 500 ~
1,300 ° C., preferably 1,050 to 1,200 ° C., heating time 1 minute to 10 hours, preferably 10 minutes to
The method for producing a vapor-grown carbon fiber is characterized in that it is 3 hours, more preferably 1 to 2 hours.

The present invention will be described in detail below.

(First Step) In the method of the present invention, in the first step, the carbon compound and the metal compound, which are the raw materials for producing the fiber, are heated to produce the fiber.

Examples of the carbon compound include, for example, JP-A-60-54998, JP-A-60-54999, JP-A-60-181319, and JP-A-60-185818.
No. 60-224815 and 60-224.
The carbon compounds described in JP-A No. 816 and JP-A No. 61-34221 can be used. Specifically, saturated aliphatic hydrocarbons such as methane and pentane, unsaturated aliphatic hydrocarbons such as pentene, hexene, octene and butadiene, aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene and anthracene. Preferred examples include cyclic hydrocarbons such as cyclopentane, cyclohexane, dicyclopentadiene, and dicyclopentadienyl, and carbon monoxide and carbon dioxide. These may be used alone or in combination of two or more. Incidentally, these carbon compounds may contain one or more atoms such as P, O, N, S, P and halogen in the molecule.

Among the above carbon compounds, aromatic hydrocarbons are preferable, aromatic hydrocarbons other than polycyclic aromatic hydrocarbon compounds are more preferable, and benzene, toluene and xylene are particularly preferable. It is a monocyclic aromatic hydrocarbon compound which may have a substituent such as.
If a polycyclic aromatic hydrocarbon compound is used as a carbon compound in the first step in which a metal compound is present, soot and amorphous carbon are produced, and such by-products are brought into the second step together with the crude fiber material. As a result, soot, amorphous carbon and the like grow as they are in the second step, which may cause an unfavorable situation in which the production rate of vapor grown carbon fibers in the product decreases.

Examples of the metal compound include organometallic compounds having a carbon bond with a metal, such as metallocene, metal carbonyl, alkyl metal, allyl complex, metal acetyl compound, π-complex and chelate type compound.
A metal compound having an oxygen bond with a metal, for example, a β-diketone metal, a β-ketoester metal compound, a metal alkoxide, a metal carboxylic acid compound, a metal sulfonate compound, a metal sulfur compound having a bond between a metal and sulfur, For example, thioalkoxide metal compounds,
And an inorganic metal compound composed of a metal and an inorganic compound,
For example, FeCl ₃ , Fe (NO) ₄ , Co (NO) ₂ C
1 and the like. The metal in these metal compounds is preferably a transition metal, and particularly preferably iron, nickel or cobalt of Group VIII of the periodic table.

The carbon compound is usually used in a gas state together with a carrier gas. If any of the carbon compounds is a solid under normal conditions, the solid carbon compound is dissolved in a suitable solvent and the solvent solution obtained is atomized to form a spray state together with the carrier gas or independently of the carrier gas. Alternatively, a solvent solution in a spray state may be supplied to the reaction tube without using any carrier gas.

Examples of the carrier gas include helium, argon, xenon, hydrogen, nitrogen, ammonia,
Examples thereof include hydrogen sulfide and nitrogen dioxide. These may be used alone or in combination of two or more. The carbon compound can be used by appropriately mixing it with other compounds as long as the object of the present invention is not impaired.

The concentration of the metal compound with respect to the carbon compound is usually 0.1 to 10 mol%, preferably 0.5 to 3 mol%. The concentration is 0.1 mol%
If it is less than 100%, the fiber may not be produced. on the other hand,
Even if it exceeds 10 mol%, there is a case where the elementary fiber is not formed. In addition, depending on the case, 0.1 mol%, 0.
Adopt a concentration range in which 5 mol% and any of the concentration values described in the examples are lower limits, and 3 mol%, 10 mol% and any of the concentration values described in the examples are upper limits. You can also

When a carrier gas is used in the first step, the concentration of the carbon compound with respect to the carrier gas is usually 3 to 30 mol%, preferably 5 to 10 mol%. If the concentration is less than 3 mol%, no fiber may be produced. On the other hand, if it exceeds 30 mol%, soot may be mixed in. In addition, depending on the case,
A concentration range in which 3 mol%, 5 mol% and any of the concentration values described in the examples are lower limit values, and 10 mol%, 30 mol% and any of the concentration values described in the example are upper limit values. Can also be adopted.

The reaction time in the first step is
It is usually 0.1 to 60 minutes, preferably 1 to 10 minutes, more preferably 2 to 5 minutes. The reaction time is
If it is less than 0.1 minutes, the production of the elementary fibers may not be sufficient. On the other hand, if it exceeds 60 minutes, the adhesion of amorphous carbon may be remarkably high and it may not be possible to obtain high-quality elementary fibers.

The heating temperature in the first step is
Usually 500 ° C to 1,300 ° C, preferably 1,050 ° C
~ 1,200 ° C. If the heating temperature is lower than 500 ° C, the formation of the elementary fibers may not be sufficient. on the other hand,
If the temperature exceeds 1,300 ° C, the amount of soot generated may increase, which may be a disadvantage.

In the first step, a reaction tube known per se if the carbon compound as the raw material for producing the elementary fiber and the metal compound can be reacted to grow the elementary fiber,
It can be carried out in a reactor, a reactor or the like.

In the above first step, the metal in the metal compound serves as a catalyst, and the elementary fiber grows in the fiber direction with this metal as the nucleus. Therefore, the obtained elementary fiber usually incorporates a metal compound at one end or both ends, and the diameter thereof is usually 0.01 to 0.5.
μm, and the aspect ratio (L / D) is usually 2 to 1
It is 10,000.

From another point of view, in this first step, the diameter is 0.01 to 0.5 μm, preferably 0.0.
It is preferable to produce a raw fiber having an aspect ratio (L / D) of 5 to 0.3 μm and usually 2 to 10,000, preferably 10 to 200. The elementary fibers thus grown in the fiber direction can be grown in the thickness direction of the elementary fibers in the next second step to obtain vapor-grown carbon fibers having a desired diameter and aspect ratio.

(Second Step) The raw fiber obtained in the first step has the diameter as described above. In order to obtain a vapor-grown carbon fiber having a diameter larger than this diameter range, it is better to further lengthen the heating time in the first step, or to increase the reaction amount of the carbon compound. In some cases, impurities such as amorphous carbon are remarkably produced, and high-quality vapor-grown carbon fibers cannot be obtained. Therefore, in the present invention, a second step described below is provided to promote the growth of the elemental fibers in the radial direction (thickness direction).

In the second step of the method of the present invention, a raw material for thickness growth containing at least one selected from the group consisting of polycyclic aromatic hydrocarbon compounds and their derivatives, and the raw material for thickness growth produced in the first step. The elemental fibers are grown by heating the elemental fibers. In the present invention, the elemental fibers supplied to the second step may be elemental fibers produced in the first step and further grown in the thickness direction.

Of course, the elemental fibers produced in the first step are further grown in the thickness direction in the first step, and then the elemental fibers are grown in the second step (the element fibers are slightly grown in the thickness direction).
When growing in the thickness direction (former), the raw fibers produced in the first step are supplied to the second step without growing in the thickness direction, and the raw fibers are moved in the thickness direction in the second step. The latter is superior when compared to the case of growing (latter).

In the first step, a complicated reaction such as generation of catalyst particles by thermal decomposition of a metal compound and formation of raw fibers using the catalyst particles proceeds. When the elemental fibers produced in the first step are grown in the thickness direction, deactivation of the catalyst particles occurs and at the same time impurities such as soot and amorphous carbon are produced. On the other hand, in the second step, carbon C on the fiber
The VD reaction takes place and is simple. However, the impurities produced in the first step may be brought into the second step, which may cause deterioration in the quality of the vapor-grown carbon fiber obtained in the second step. Further, the reason why the latter is superior to the former is considered as follows. That is,
When the raw fibers are produced in the first step, the growth of the raw fibers in the fiber direction and the thickness direction are observed. Therefore, in the first step, when the growth in the fiber direction and the growth in the thickness direction proceed at the same time, an elementary fiber having a variation in L / D is obtained, and L
This is because when L / D is increased in the thickness direction in the second step, the L / D is more and more varied, and the intended vapor-grown carbon fiber cannot be obtained.

Examples of the polycyclic aromatic hydrocarbon compound and its derivative contained in the thickness-growing raw material include:
Naphthalene, phenanthrene, anthracene, pyrene,
Examples thereof include polycyclic aromatic hydrocarbon compounds such as naphthacene, chrysene, picene, tetralin, triphenylene, perylene, benzopyrene, coronene and ovalen, and derivatives thereof. In the present invention, it is necessary that the thickness-growing raw material contains at least one selected from these groups. In addition, these may be used individually by 1 type, or may be used in combination of 2 or more type. Among these, naphthalene, phenanthrene, anthracene, and derivatives thereof are preferable.

Since the polycyclic aromatic hydrocarbon compound and its derivative are usually solid at room temperature,
In such a case, these can be used by dissolving them in an organic solvent known per se. It should be noted that the above raw material for thickness growth may be appropriately mixed with other compounds within a range not impairing the object of the present invention.

The organic solvent is not particularly limited as long as it can dissolve the polycyclic aromatic hydrocarbon compound, and preferred examples thereof include monocyclic aromatic compounds such as benzene, toluene and xylene. Hydrocarbons may be mentioned.

The concentration of the raw material for thickness growth with respect to the organic solvent is usually 1 to 80 mol%, preferably 10 to 80 mol%, and more preferably 50 to 80 mol%.
Is. If the concentration is less than 1 mol%, the thickness growth rate of the elementary fibers may not be improved. On the other hand, if it exceeds 80 mol%, a hydrocarbon compound may be precipitated.

In the second step, however, it is preferable to heat at least one selected from the group consisting of polycyclic hydrocarbon compounds or their derivatives and the fiber without using an organic solvent or the like. This is because the presence of an organic solvent or the like may generate soot and the like due to heating.

The thickness-growing raw material is usually used as a gaseous raw material gas together with a carrier gas.
The above-mentioned carrier gas can be used as the carrier gas. Further, other compounds can be appropriately mixed and used as long as the object of the present invention is not impaired.

In the second step, the concentration of the raw material for thickness growth with respect to the carrier gas is usually 0.5 to 30.
Mol%, preferably 1 to 10 mol%, more preferably 3 to 5 mol%. If the concentration is less than 0.5 mol%, the growth in the thickness direction may not be sufficient. On the other hand, if it exceeds 30 mol%, soot may occur.

The reaction time in the second step is
It is usually 1 minute to 10 hours, preferably 10 minutes to 5 hours, and more preferably 30 minutes to 3 hours. If the reaction time is less than 1 minute, the growth of the filament may be insufficient. On the other hand, if the time exceeds 10 hours, the fibers may adhere to each other.

The heating temperature in the second step is
Usually 500 ° C to 1,300 ° C, preferably 800 ° C to
It is 1,200 ° C. When the heating temperature is lower than 500 ° C, the growth of the elementary fibers may not be sufficient. on the other hand,
If the temperature exceeds 1,300 ° C., the amount of soot generated may increase and the quality of the vapor-grown carbon fiber may be deteriorated. Also, the conditions differ between hydrogen gas and nitrogen or argon, and when using hydrogen gas as the carrier gas,
Higher temperatures are preferred, and lower temperatures are preferred when nitrogen or argon is used as the carrier gas.

The second step can be carried out in a reaction tube, reactor, reaction device or the like known per se so long as the raw material for thickness growth can be reacted with the raw fibers produced in the first step. .

By the above second step, vapor grown carbon fiber having a sufficient size is produced. The diameter of the vapor grown carbon fiber is usually 0.5 to 8 μm, and the aspect ratio is usually 2 to 500. In addition, the thickness growth rate of the elementary fibers in the second step is usually 1 to 3 μm / h.

In the present invention, the first step and the second step may be continuously performed, or a pause time may be provided between them. In addition, the first step and the second
The steps may be performed in the same reactor or the like, or may be performed in different reactors or the like.

Next, the method for producing the vapor grown carbon fiber of the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an example of a method for producing a vapor grown carbon fiber of the present invention. Carrier gas supply line 3
The carrier gas supplied by the heating furnace 2 is 500 ° C. together with the raw material for raw fiber production sent from the raw material for raw fiber production tank 6 by the raw material feed pump 4 for raw fiber production.
The reaction tube 1 heated to ˜1,300 ° C. is continuously supplied for the reaction time of the above-mentioned first step, and the elementary fibers are generated in the reaction tube 1. The gas passing through the reaction tube 1 is exhausted from the exhaust line 8. Next, while maintaining the temperature in the reaction tube 1 by the heating furnace 2, the raw material tank 7 for growing the fiber is added to the reaction tube 1.
The raw material for thickness growth sent by the raw material supply pump for thickness growth 5 and the carrier gas supplied from the supply line 3 are continuously supplied for the reaction time of the second step.
The elementary fibers existing in the reaction tube 1 are grown. The gas passing through the reaction tube 1 is exhausted from the exhaust line 8.

By the above reaction, vapor-grown carbon fibers having a sufficiently large thickness are produced in the reaction tube 2.

[0044]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples.

(Example 1) When vapor-grown carbon fibers were produced under the following conditions, the yield in the second step was 40%.
And the thickness growth rate was 2 μm / h. When the product was observed by SEM, the ratio of carbon fibers was 95%. The diameter of the obtained vapor grown carbon fiber is 2
μm, and the aspect ratio was 50.

<Production conditions><< First step >> Composition of raw material for producing fiber: 0.5 g of ferrocene per 100 g of benzene Supply amount of raw material for fiber production; 2 ml / min Type and supply amount of carrier gas; Hydrogen 10 liters / minute Furnace temperature; 1050 ° C Reaction time; 1 minute << Second step >> Composition of raw material for growing fiber; 30 g of naphthalene (naphthalene / benzene) for 100 g of benzene Supply amount of raw material for growing fiber; 2 ml / Min Type and supply amount of carrier gas; hydrogen, 10 liters / min Furnace temperature; 1100 ° C Reaction time; 60 minutes (Comparative Example 1) Except that the composition of the raw material for thickness growth in the second step is changed to benzene only When vapor grown carbon fiber was produced in the same manner as in Example 1, the yield of the product was 20%.
And the thickness growth rate was 1.2 μm / h. Moreover, when the product was observed by SEM, the ratio of carbon fibers was 90%.

The vapor grown carbon fiber thus obtained had a diameter of 1.2 μm and an aspect ratio of 90.

(Comparative Example 2) Vapor grown carbon fibers were produced in the same manner as in Example 1 except that the composition of the thickness growing raw material in the second step was changed to benzene only and the furnace temperature was changed to 1150 ° C. As a result, the yield of the product was 35%, and the thickness growth rate was 1.4 μm / h. In addition, the product is SE
When observed by M, the proportion of carbon fibers was 60%.

The vapor grown carbon fiber thus obtained had a diameter of 1.4 μm and an aspect ratio of 80.

Example 2 In the second step of Example 1, creosote oil (a mixture of polycyclic aromatic hydrocarbons such as naphthalene and anthracene) was used in place of naphthalene / benzene as a raw material for growing fiber. Then, this was melted by heating at 60 ° C., the resulting melt was filtered with a filter, and the gasified product was supplied together with a carrier gas into the reaction tube. The supply amount of the raw material for growing the fiber, the kind and supply amount of the carrier gas, the furnace temperature, the reaction time, etc. are the same as those in the above-mentioned embodiment.

The yield of the obtained vapor grown carbon fiber was 86%.
The thickness growth rate was 1.7 μm / h, and the fiber ratio was 92%.

(Example 3)

[0053]

According to the present invention, it is possible to provide an industrially advantageous method for producing a vapor-grown carbon fiber, which can efficiently produce a high-quality vapor-grown carbon fiber in a high yield in a short time. it can.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a method for producing a vapor-grown carbon fiber according to the present invention.

[Explanation of sign]

DESCRIPTION OF SYMBOLS 1 ... Reaction tube, 2 ... Heating furnace, 3 ... Carrier gas supply line, 4 ... Elementary fiber production raw material supply pump,
5 ... Thickness growth raw material supply pump, 6 ... Raw material fiber production raw material tank, 7 ... Thickness growth raw material tank, 8 ...
..Exhaust lines,

Claims (3)

[Claims] 1. A first step of heating a raw material for producing an elementary fiber containing a carbon compound and a metal compound to produce an elementary fiber, an elementary fiber produced in the first step and a polycyclic aromatic hydrocarbon A second step of heating at least one selected from the group consisting of a compound and its derivative to grow the elementary fibers in the thickness direction, the method for producing a vapor-grown carbon fiber. 2. A first step in which a raw material for producing a fiber containing a carbon compound and a metal compound are heated to produce a fiber, and the fiber produced in the first step and a polycyclic aroma as the carbon compound. A second step of heating at least one selected from the group consisting of group hydrocarbon compounds and derivatives thereof to grow elementary fibers in the thickness direction, a method for producing a vapor-grown carbon fiber. . 3. The method for producing a vapor-grown carbon fiber according to claim 1, wherein the carbon compound in the first step is a carbon compound excluding a polycyclic aromatic hydrocarbon compound.