JPH0359115A - Production of carbon fiber by vapor-phase method - Google Patents

Abstract

PURPOSE:To obtain the title fiber having high strength, high elasticity and high electrical conductivity and high corrosion resistance free from admixture of carbonaceous chain material by using a condensed polycyclic aromatic compound dissolved in benzene (derivative) as a raw material hydrocarbon. CONSTITUTION:A condensed polycyclic aromatic compound (derivative) having 2-4 rings is dissolved in benzene (derivative) and used as a raw material hydrocarbon to give the objective fiber.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing carbon fiber using a vapor phase method.

[Prior Art] Conventionally, typical methods for producing carbon fibers include a method of carbonizing organic fibers such as polyacrylonitrile, and a method of recirculating pitch after melt-spinning.

On the other hand, there is a method for manufacturing vapor-grown carbon fiber that uses a hydrocarbon compound as a raw material and pyrolyzes it in the vapor phase to produce filamentous carbon.Those produced by this method have high strength, high elasticity, high conductivity, It has excellent properties such as high corrosion resistance.

The production of vapor-grown carbon fiber involves scattering catalyst particles of metal or metal compound onto a substrate made of porcelain such as alumina or graphite, introducing this into a reactor, and then producing carbon fibers on the substrate. A method for extracting
103528, JP-A-52-107329, JP-A-60-27700, etc.) are known.

Furthermore, in recent years, a method has been developed in which a metal or metal compound catalyst and a hydrocarbon raw material are supplied to a high-temperature reactor, and the reaction is carried out in the presence of the catalyst (for example, JP-A-58-180615,
JP-A-60-54998, JP-A-60-231821
etc.) were developed. According to this method, since a substrate or the like is not required, the productivity is excellent and it is possible to obtain vapor-grown carbon fibers on an industrial scale.

In these conventional methods, hydrogen, argon, etc. are used as a carrier gas, and the raw material hydrocarbons are aliphatic hydrocarbons such as methane and ethane, and aromatic hydrocarbons mainly having one ring, such as benzene or benzene derivatives. A group hydrocarbon or a condensed polycyclic aromatic compound such as naphthalene having two or more rings is used.

[Problem to be solved by the invention] By the way, the method for industrially producing vapor-grown carbon fiber is 1.
It is necessary to strictly control the reaction conditions, such as the amount of carrier gas aeration and the amount of raw material gas supplied (e.g., Japanese Patent Application Laid-open No. 63-219630), and even if these are strictly carried out, complete fibrous formation may occur. It was difficult to obtain vapor grown carbon fiber. The difficulty in obtaining fibrous materials in the production of vapor-grown carbon fibers is, for example, as disclosed in Japanese Patent Application Laid-Open No. 61-32.
This is due to the fact that carbonaceous chains such as those disclosed in No. 507 are often mixed in. The contamination of carbon chains not only impedes the product value of the vapor-grown carbon fiber itself, but also, for example, when composited with resin, the carbon chains act as foreign substances and may not exhibit sufficient physical properties. Not only is this not possible, but in extreme cases, the properties of the composite itself may be deteriorated. Furthermore, attempting to mechanically separate such carbonaceous chain bodies from the obtained vapor-grown carbon fibers not only complicates the manufacturing process but also increases costs, which is not preferable.

Therefore, as mentioned above, it is necessary to strictly control the mixing ratio of the carrier gas and the raw material hydrocarbon in the reactor. Regarding the supply method of feedstock hydrocarbons, gaseous hydrocarbons such as methane and ethane can be accurately measured using a flow meter, and liquid hydrocarbons such as benzene can be supplied in a fixed amount using a metering pump. be. By the way, condensed polycyclic aromatic raw materials such as naphthalene and anthracene are solid at room temperature, and are generally supplied after being vaporized. In the case of vaporization in this manner, quantitative supply is not carried out, and as a result, only vapor-grown carbon fibers with irregular fiber shapes mixed with, for example, carbonaceous chain particles are obtained.

SUMMARY OF THE INVENTION The present invention aims to solve these problems and to obtain a vapor-grown carbon fiber containing only fibrous material without contamination of carbonaceous chain bodies.

[Means to solve 11g] The present inventors have found that there is no contamination of carbonaceous chain bodies.

In order to obtain high quality vapor grown carbon fiber with excellent fibrous properties,
It was discovered that a distant relative can be achieved by using a specific raw material and supplying it quantitatively to the reactor, leading to the present invention.

That is, the gist of the present invention is to use a fused polycyclic aromatic compound having 2 to 4 rings or a derivative of the compound as the first component of the hydrocarbon raw material, and to dissolve '7seizo into the first component. By mixing and using a monomer derivative as a solvent, it is possible to obtain high-quality vapor-grown carbon fibers that are free from contamination with carbonaceous chain bodies. Examples of the fused polycyclic aromatic compound having 2 to 4 rings used in the present invention include naphthalene and its derivatives α-methylnaphthalene, β-methylnaphthalene, 2,
3-Dimethylnaphthalene, or anthracene and anthracene derivatives, phenanthrene and phenanthrene derivatives, as well as naphthacene.

Examples include pyrene and derivatives of the compound.

Further, examples of the second component that dissolves the above compound include benzene, toluene, xylene, and the like.

In general, the mechanism of gas-phase carbon fiber production is that the raw material hydrocarbon is thermally decomposed to become atomic carbon, which comes into contact with a reduced and purified metal catalyst, and the carbon atoms diffuse on the surface of the catalyst metal, or dissolve into the catalyst metal. death.

It is said that a graphite structure is formed through catalytic action, forming a fibrous carbonaceous substance. Here, it is said that many aliphatic and aromatic hydrocarbons can be used as the raw material hydrocarbon.1 The present inventors found that there is a difference between the type of raw material hydrocarbon and the morphology and structure of the produced carbon fiber. We found that there is a close relationship, and that these are caused by the structure and thermodynamic properties of the raw materials. The structure of the raw material hydrocarbon is classified into ITI aliphatic or aromatic, or whether it is a saturated compound or an unsaturated compound, and its thermodynamic properties are whether it is an exothermic reaction at one reaction source level. It is classified as an endothermic reaction. For example, methane and ethane, which are aliphatic saturated hydrocarbons, have an endothermic reaction at the reaction temperature, while aromatic hydrocarbons such as benzene and naphthalene have an exothermic reaction. The present inventors focused on the basic structure and thermodynamic properties of hydrocarbons, and as a result of intensive research, we found that the fiber morphology and fiber structure of vapor-grown carbon fibers are aromatic hydrocarbons that exhibit exothermic reactions. I found something nice.

Among aromatic hydrocarbons, condensed polycyclic aromatic hydrocarbons are particularly preferred as the raw material hydrocarbon. However, since fused polycyclic aromatic hydrocarbons are usually solid at room temperature and have vaporizability, there are many obstacles to quantitatively supplying them to a reactor. In order to solve this problem, it is optimal to select a liquid aromatic hydrocarbon such as benzene or a benzene derivative that dissolves the fused polycyclic aromatic compound, and also a liquid aromatic hydrocarbon such as benzene or a benzene derivative. As the condensed polycyclic aromatic compound that dissolves in the liquid aromatic hydrocarbon, those having 2 to 4 rings are most suitable. For example, when benzene is used as a solvent and naphthalene is used as a polycyclic aromatic hydrocarbon, naphthalene is dissolved in benzene at 30%
It is possible to dissolve wt%. Furthermore, when anthracene is used, it can be dissolved in an amount of about 20 wt%. In this manner, by dissolving the fused polycyclic aromatic compound in a solvent, it becomes easy to supply the fused polycyclic aromatic compound in a quantitative manner to the reactor.

To explain further, if a raw material that satisfies these conditions is selected, it is possible to obtain a vapor-grown carbon fiber that is only in the form of fibers without any contamination of carbonaceous chain bodies, and is sufficiently satisfactory from the structural point of view. Fibers with developed graphite properties are obtained. The reason why these excellent vapor-grown carbon fibers are obtained is not clear, but it is thought to be due to the structural unit of carbon when subjected to the catalytic action of fine metal particles. That is, the structural unit that undergoes catalytic action is expected to be a monomer or polymer of an aromatic compound, rather than an atomic carbon or a linear carbon compound. Although some of these condensed polycyclic aromatic compounds decompose thermally, they tend to generate aromatic radicals and easily become abundant, and as a type of aromatic polymer, thermodynamically stable graphite undergoes catalytic action. It is expected that the structure will eventually become wl, male-shaped. The reason why aromatic compounds are preferable to aliphatic hydrocarbons is thought to be that aromatic polymers having thermodynamically stable aromatic rings as a skeleton can be obtained with high probability. Furthermore, the exothermic reaction of the raw materials is expected to serve as a driving force to maintain the temperature necessary for the reaction and to promote the catalytic action.

In the present invention, the metal fine particles include conventionally known Fe,
A compound that generates fine particles by decomposing a compound containing these metals such as Co, Ni, and ferrocene is used, and the generation temperature is also the same as before, but in particular, it is 1100°C to 130°C.
The temperature is preferably 0° C., and in addition to forming fine fibers in space, it is also possible to form relatively long fibers over a long period of time on a substrate.

The present invention will be explained in more detail below with reference to Examples.

[Example 1 FIG. 1 shows a diagram of the apparatus used in this example.

Naphthalene was dissolved in benzene to adjust the naphthalene concentration to 30% by weight, and ferrocene was mixed at a ratio of 2% by weight with respect to the mixed solution, and the mixture was poured into a raw material supply tank 1. followed by 120
4 in a reactor with an inner diameter of 80 mm maintained at 0°C and hydrogen bubbled through at a rate of 20 liters per minute by a flow meter 3.
Then, the feed pump 2 was used to feed the raw material at a rate of Log per minute. After 1 minute had elapsed since the IJK material was supplied, the reaction was stopped, the reactor 4 was cooled, and the carbonaceous product was taken out from the box 5. In the figure, 6 is a filter, and 7 is a gas outlet. Weighing the carbon fiber produced, it is 62
g, and the yield based on the amount of raw material supplied was 62% by weight. Furthermore, when this bioacid was observed with a scanning electron microscope,
The diameter is 0. The fibers were of good quality, measuring 3 μm to 0.5 μm and having a length of 500 μm or more, with no contamination of carbonaceous chain bodies.

In addition, when this fiber was subjected to X-ray diffraction according to the Gakushin method,
The diffraction angle of the (OO2) plane is 26. Engineering.

It was a fiber with excellent graphitic properties.

[Comparative Example 1] Using the apparatus shown in FIG. 1, the same reaction as in Example 1 was carried out except that only benzene was used as the raw material. Carbon yield was 45 gw. In addition, observation using a scanning electron R mirror shows that it contains many carbonaceous chains, and X&! Diffraction revealed a mixture with peaks at diffraction angles of 25.0 and 25.4 degrees.

[Comparative Example 2] The same reaction as in Example 1 was carried out using the apparatus shown in FIG. 1, except that n-hexane was used as the raw material. The carbon yield was extremely low at 2%, and observation using a 1M scanning electron microscope revealed only carbonaceous chains and no fibers.

[Effects of the Invention] The vapor-grown carbon fiber, which is fibrous only and is not mixed with carbonaceous chain bodies, has an excellent reinforcing effect and can be expected to be used in a variety of fields.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus for manufacturing vapor-grown carbon fiber of the present invention. Engineering: raw material tank, 4: reactor, 6: filter

Claims (1)

[Claims] In a method for producing carbon fiber by a gas phase method, a fused polycyclic aromatic compound or a fused polycyclic aromatic compound derivative having 2 to 4 rings is used as a raw material hydrocarbon by dissolving it in benzene or a derivative thereof. A method characterized by: