JPS62282020A - Production of carbon fiber - Google Patents

Abstract

PURPOSE:To efficiently obtain carbon fibers hardly contaminated by soot, by feeding a carbon source compound, catalyst source compound, sulfur compound and carrier gas to a heating zone at a specific temperature or above at specific feed rates. CONSTITUTION:A carbon source compound, e.g. methane, ethane, ethylene, etc., catalyst source compound, e.g. FeCl3, etc., carrier gas, e.g. H2, He, N2, Ar, etc., and sulfur compound, e.g. methyl thiol, etc., are fed to a heating zone to produce carbon fibers. In the process, the temperature of the heating zone is set at >=1,300 deg.C and the ratio of the feed rate (g) per unit time of the carbon source compound to the feed rate (mol) per unit time of the carrier gas fed to the heating zone is set at >=0.04mol/g.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing carbon fibers, and more specifically, the present invention relates to a method for producing carbon fibers, and more specifically, the present invention relates to a method for producing carbon fibers, and more specifically, the present invention relates to a method for producing carbon fibers. The present invention relates to a method for producing carbon fibers in which fibers are produced in a heated zone space.

(Prior art) Carbon fiber has excellent properties such as high strength and high modulus of elasticity.
It is a material that has been in the spotlight in recent years as a variety of composite materials. Conventionally, carbon fibers have been mainly produced by carbonizing organic fibers, but carbon fibers produced by thermal decomposition and catalytic reactions of hydrocarbons are also known. The latter vapor-grown carbon fiber has superior crystallinity and superior crystallinity compared to the former carbon fiber.
Because it has orientation, it is expected to be used in a wide variety of fields as a composite material that has both high strength and high elastic modulus.

A general method for manufacturing carbon fibers using the vapor phase method involves spraying fine particles made of transition metals, as shown in, for example, "Kogyo Materials, July 1980 Issue, p. 109 (Endo, Koyama)". The fiber-generating base material is placed in a reaction tube of an electric furnace, and after the furnace temperature is brought to a predetermined temperature, a mixed gas of hydrocarbon and hydrogen is passed through the reaction tube to carbonize it, producing carbon fibers on the base material. be.

However, methods using such substrates have low productivity because the reaction zone is two-dimensional and the process is complicated.

On the other hand, JP-A-58-180615 describes a method in which ultrafine powder of a high-melting point metal or a compound of the metal is suspended in a hydrocarbon thermal decomposition zone. It has not been possible to find a method with excellent productivity because secondary particles are easily formed and the catalytic effect is difficult to exhibit.

On the other hand, JP-A-60-54998, JP-A-60-181
No. 311, JP-A-60-185818, JP-A-60-
No. 224815 and Japanese Unexamined Patent Publication No. 60-224816 describe a method of subjecting a mixed gas of a transition metal compound gas, a carbon source compound gas, and a carrier gas to a high-temperature reaction. However, in these methods, the amount of the transition metal compound used is much larger than the carbon source compound, and the yield is low. Further, according to the studies of the present inventors, the amount of raw materials supplied was increased in order to improve the production amount per hour (this resulted in problems such as a further decrease in the yield and the contamination of soot).

(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned problems and provide a method for producing carbon fibers that has high productivity and yield and is hardly contaminated with soot.

(Means for Solving the Problems) The present invention provides a method for producing carbon fiber by supplying a carbon source compound, a catalyst source compound, a carrier gas, and a sulfur compound to a heating zone, in which the temperature of the heating zone is increased to 1300°. C or more and the amount of carrier gas (mon) supplied to the heating zone per unit time is calculated as the amount of carbon source compound supplied per unit time (mon).
This is a method for producing carbon fiber, characterized in that OoQ 4 m o (1/g or more) is set relative to g).

The carbon source compound in the present invention is a compound that can precipitate carbon by heating to 800°C or higher, and covers carbon compounds in general. For example, CO, alkane compounds such as methane and ethane, alkene compounds such as ethylene and butadiene, alkyne compounds such as acetylene, aromatic compounds such as benzene, toluene, styrene, naphthalene and anthracene, cyclohexane, cyclopentadiene and dicyclopenta Examples include alicyclic hydrocarbon compounds such as Jen, derivatives thereof such as nitrogen, oxygen, halogen, etc., gasoline, kerosene, heavy oil, etc., and mixtures thereof may also be used.

The amount (g) of the carbon source compound supplied to the heating zone is preferably 0.5 g/β·min or more per minute per volume 11 of the heating zone, particularly 1.0 g#!・Minutes or more, 30.0 g/
7!・It is more preferable to use a branch office. If the amount supplied is too small, soot tends to be mixed in, while if it is too large, the yield tends to decrease and soot also tends to be mixed.

Catalyst source compounds in the present invention include FeCz,...
, Fe (No)4, NiCl2, Co (NO)2
Inorganic transition metal compounds such as CX, Fe (C5H5)2,
Ni (C5Hj)2, Co (Cg Hg)2, F
e (Co) 5, Fe2 (CO) 1, Ni
Examples include organic transition metal compounds such as (C0)4, and transition metal compounds such as iron acetylacetonate, iron carboxylate, iron alkoxide, iron aryloxide, nickel thioalkoxide, cobalt alkoxide, and iron thioacetate. Two or more of these catalyst source compounds may be used simultaneously. Furthermore, as a catalyst source compound, JP-A-60-54998, JP-A-60-54999, JP-A-60-181319, JP-A-60-185818, JP-A-6 (1989-1-22481)
No. 5, Japanese Patent Application Publication No. 1-224816, Japanese Patent Application Publication No. 1986-2
No. 31822, Japanese Patent Application No. 59-231967, Japanese Patent Application No. 1983
Compounds described in Japanese Patent Application No. 0-58813, Japanese Patent Application No. 60-58819, Japanese Patent Application No. 113108-1982, Japanese Patent Application No. 123201-1982, etc. may be used.

The amount (mob) of the catalyst source compound supplied to the heating zone is lX10' with respect to the mass (g) of the carbon source compound supplied.
moJ/g or more, 3 X 10-3mo It 7g or less is preferable, especially lXl0-'mol/g or more, I
1.7 g or less of X 10-3mo is more preferably used. If the supply is too low, it tends to be contaminated with soot;
If the amount is too large, the yield tends to decrease.

As the carrier gas in the present invention, H2 gas, He
Gas, N2 gas, Ne gas, Ar gas, Kr gas, CO
. Examples include gases mainly composed of gas and NH3 gas, and mixtures thereof may also be used.

In the present invention, the amount of carrier gas supplied to the heating zone per unit time (mo7 is o, relative to the amount of carbon source compound supplied per unit time (g)).

4 m o 7! /g or more. Carrier gas amount is 0.04 m o j! /g, the proportion of soot obtained increases. Carrier gas amount is 0.04 m o
A/g or more and 5゜9 m o 1/g or less are preferable, particularly 0.08 m o 172 or more and 0.25 m o 1/g or less
m o n! /g or less is more preferable.

If the amount of carrier gas is large, the yield tends to decrease.

The carrier gas used varies depending on the carbon source compound used, but is 30 VoI! % or more is preferably hydrogen gas, particularly preferably 50 VoJ% or more. If the amount of hydrogen gas is small, soot tends to get mixed in.

Examples of the sulfur compound in the present invention include hydrogen sulfide, carbon disulfide, and organic sulfur compounds, and organic sulfur compounds are particularly preferably used. Examples of organic sulfur compounds include thiols such as methylthiol, ethylthol, butylthiol, and phenylthiol; sulfides such as dimethyl sulfide, diethyl disulfide, and phenylmethyl sulfide; sulfoxides such as dimethyl sulfoxide, diethyl sulfoxide, and diphenyl sulfoxide; Sulfones such as dimethylsulfone and diethylsulfone, sulfur-containing heterocyclic compounds such as thiophene and isobenzothiophene, other sulfenic acids, sulfenic esters, sulfonic acids, sulfonic esters and their anhydrides, sulfinic acids, sulfinic acids esters,
Thiol sulfinates, thiocarbonyl compounds, thiocarboxylic acids, thiocarboxylic acid esters, dithiocarboxylic acids, sulfines, thiocarboxylic acid derivatives S-
Examples include oxides, sulfonium ylides, and sulfurans. These may be used alone or in combination of two or more.

The amount (mob) of the sulfur compound supplied to the heating zone is 1 × 10-'mo with respect to the mass (g) of the carbon source compound supplied.
487g or more and l x 10-'mo 12/g or less are preferable, especially lXl0-'mo7! /gm upper 7! X
More preferably, it is 10-'moJ/g or less. If the amount of sulfur compounds is too large or too small, there is a tendency for more soot to be mixed in.

The temperature of the heating zone in the present invention is 1300°C or higher9,
+0 for 6. - is reactor i. It is necessary to heat the inner wall temperature to 1300°C or higher. Below 1300°C, increasing the amount of raw materials (carbon source compound, catalyst source compound, carrier gas and sulfur compound) supplied to the heating zone will reduce the yield;
Also, more soot gets mixed in. Inner wall temperature is 1300~
The temperature is preferably 2100°C, and particularly preferably 1330 to 1900°C. If the inner wall temperature is too high, there is a tendency for soot to become mixed and trapped. The heating method is not particularly limited, but examples include methods such as electric furnace heating, infrared heating, plasma heating, laser heating, combustion heat utilization, and reaction heat utilization, among which electric furnace heating is convenient.

The method of supplying the carbon source compound, the catalyst source compound, the carrier gas, and the sulfur compound to the heating zone is not particularly limited. For example, each of them can be supplied as a gas, as a mixed gas, as a liquid, or as a mixture. Any method such as a method of supplying in liquid form, a method of supplying in powder form, or a combination thereof may be used. Further, the supply nozzle position and temperature are not particularly limited either.

(Effects of the Invention) According to the method of the present invention, carbon fibers containing almost no soot can be obtained in good yield. Furthermore, productivity per unit time can be greatly improved.

(Example) Examples 1 to 7, Comparative Examples 1 to 2 As shown in FIG. 1, an electric furnace 1 having a graphite heater
(length of soaking zone 85c+n) and molybdenum pipe 2 (inner diameter 6
0 m, length 2fn) was installed, and a box 3 was connected to one end of the molybdenum pipe 2. and filter 8 in box 3
was installed to collect the fibers coming out of box 3. Further, at the other end of the molybdenum tube 2, an introduction vibrator 4.5 for supplying the raw material to the heating zone and an introduction nozzle 6.7 were installed at the tip thereof.

After replacing the inside of the electric furnace 1 and the molybdenum tube 2 with nitrogen,
The inner wall temperature of the molybdenum tube 2 was set to the temperature shown in Table 1. Thereafter, the inside of the tube was replaced with hydrogen gas, and hydrogen gas was introduced from the introduction vibrator 5. Next, a solution in which a catalyst source compound and a sulfur compound were dissolved in benzene at the feed rate (8 degrees) shown in Table 1 was jetted from the introduction pipe 4 into the pipe. After introducing this Hensen's solution for 5 minutes, only hydrogen gas was introduced into the tube for another 5 minutes. These results are summarized in Table 1.

Many of the carbon fibers obtained have a diameter of 0.2μ or less,
Also, most of the shapes were straight.

Example 8.9 A molybdenum tube 2 having an inner diameter of 50 mm was installed in an electric furnace 1 (soaking zone marked 70) as shown in FIG.

The electric furnace 1 consists of a heater 11 whose outside is insulated with a heat insulating material 10 and covered with a casing 9.

The same procedure as in Example 1 was conducted except that toluene was used as the carbon source compound, ferrocene was used as the catalyst source compound, and thiophene was used as the sulfur compound. These results are shown in Table 2.

Table 2

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are sectional views of a carbon fiber manufacturing apparatus, each showing an example of a preferred embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Electric furnace, 2...Reaction container, 3...Box for storing products, 4.5...Introduction pipe, 6
．． 7...Introduction nozzle, 8...Filter.

Claims (1)

[Claims] (1) In a method for producing carbon fiber by supplying a carbon source compound, a catalyst source compound, a carrier gas, and a sulfur compound to a heating zone, the carrier gas is supplied to the heating zone per unit time to maintain the temperature of the heating zone at 1300°C or higher. The amount (mol) is 0 relative to the supply amount (g) of the carbon source compound per unit time.
．． A method for producing carbon fiber, characterized in that the carbon fiber content is 0.4 mol/g or more.