JPS58156513A - Carbon powder having thickly grown fine carbon cilia - Google Patents

Abstract

PURPOSE:A globular particulate carbon material like aegagropila, useful as a reinforcing material in preparing a composite material comprising a resin, metal, inorganic material, etc. as a parent material, having thickly grown fire carbon cilia on the surface. CONSTITUTION:A particulate carbon material having >=100 grown carbon cilia having <=10mu average fiber diameter per mm.<2> surface area on the surface of nearly spherical particulate carbon. The carbon material is prepared by heating a sulfur-containing carbon substrate (e.g., carbonized powder obtained by calcining fine powder of sulfonated polystyrene at high temperature) in an atmosphere of a carbon source(e.g., lower hydrocarbon such as methane, propylene, etc.) at about 700-1,500 deg.C, growing carbon formed by the thermal decomposition on the carbon substrate in a gaseous phase. When a carbon substrate containing no sulfur is used, sulfur (compound)(e.g., H2S) may be added to the atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the following method:
It relates to a carbon material with a sea gall-like (or cone-like or cone-like) shape that is made of densely packed microscopic carbon cilia with high strength and high elastic modulus produced by a vapor phase growth method using thermal decomposition of hydrocarbons.

First, the present inventors prepared hydrocarbons in a non-oxidizing atmosphere at 70%
It has been discovered that carbon fibers with high strength and high modulus of elasticity can be produced in high yield by coexisting sulfur or sulfur compounds during thermal decomposition at 0-1500''C (Japanese Patent Laid-Open No. 56-1189
Publication No. 13). In particular, when a polyaromatic compound such as naphthalene or anthracene is used as a carbon source and a vapor phase growth reaction is carried out in the presence of sulfur or sulfur compounds, carbon fibers can be produced at a high yield of 10 to several 10%. We showed that it can be obtained with The present inventors further selected a fine granular or fine powder carbon material as the substrate of the vapor grown carbon fiber, and used hydrocarbons such as carbon monoxide, methane, ethane, ethylene, acetylene, chlorofluorinated carbon, and benzene. When thermal decomposition is performed at 700-1500°C in the coexistence of sulfur or sulfur compounds using lower hydrocarbons with a relatively small number of carbon atoms, it has excellent performance and uses as described below, especially We have discovered that a microcarbon material with a cone-like (or seaweed-like or cone-like) consistency can be produced, which is ideal as a (dispersion) reinforcing material for composite materials made of plastics, metals, and inorganic materials.

Carbon fibers are produced by the so-called vapor phase growth method by thermal decomposition of hydrocarbons. It is well known that this phenomenon occurs when benzene vapor is thermally decomposed in a reducing atmosphere such as H2 at ℃. It is also known that the tensile strength and elastic modulus of the carbon fibers obtained in this way are approximately between those of carbon fibers obtained by firing organic polymer fibers such as polyacrylonitrile, rayon, and pitch. There is. Therefore, carbon fiber produced by vapor phase growth is also seen as a promising reinforcing material for composite materials, but the carbon yield of the production method is low and it has not yet been commercialized.

The present inventors have discovered a method for producing sea bile-like carbon microparticles in which microscopic vapor-grown carbon cilia with excellent tensile strength and elastic modulus are grown on the surface of a microscopic carbon substrate at a very high production density. Ta. These carbon materials can be used as (dispersed) reinforcing materials for composite materials with plastics, metals, and inorganic materials as base materials, and can not only exhibit both particle and fiber reinforcement properties at the same time, but also have excellent adhesion between the base material and the reinforcing material. It is clear that they are far superior to simple carbon particles in terms of properties.

As the inventors have already described in Japanese Patent Application Laid-Open No. 56-118913, carbon fibers grown on the surface of a heat-resistant substrate by thermally decomposing hydrocarbons in the coexistence of sulfur or sulfur compounds are The diameter usually ranges from 10 to 100 μm,
Generally, for example, the substrate has a thickness of several μm to several 100 μm.
When using carbon grains having a diameter of , carbon fibers having a diameter approximately between or larger than the diameter of the carbon grains are produced.

Therefore, the fiber diameter is too large for carbon cilia having a form and specifications suitable for the purpose of the present invention. Furthermore, the length of the produced fibers reaches several lengths, sometimes several tens of crons, which is excessive compared to the size of the carbon particles as the base material. Therefore, even if it is possible to produce fibers with relatively small diameters and lengths, the number of carbon fibers produced per carbon grain is only a few to a few dozen. The reinforced carbon material for composite materials of the present invention has 100 to 1000 microcilia with an average diameter of 10 μm or less per carbon grain with an average particle size of several μm to several 100 μm (average production density of carbon They are sea bile-like minute carbon grains that are densely grown at a ratio of 100 carbon fibers or more per 1 ad of grain surface area. The present inventors completed the present invention as a result of continued exploration and research regarding experimental conditions for various carbon materials with the aim of producing a reinforced carbon material for composite materials having such a form and specifications.

The production of the reinforced carbon material for composite materials of the present invention was made possible because the following basic requirements were met. In other words, in order to increase the production density of carbon fibers on the surface of a carbon substrate by the vapor phase growth method, the yield of carbon cilia must be extremely high, and the diameter and length of each carbon cilia must be appropriately large compared to the carbon substrate. It must be. With respect to the yield of carbon fiber produced by the vapor phase growth method, the measured value of the yield itself is not clear in the conventional production method, and this fact shows that the yield of the conventional production method is extremely low.

The present inventors have demonstrated that when hydrocarbons are pyrolyzed on various carriers at 700-1500°C in the presence of sulfur and sulfur compounds even without the coexistence of transition metals such as iron, the carbon yield is lower than that of conventional methods. has found a way to produce carbon fiber in a very advanced manner.

The present inventors applied this method to various carbon substrates, and found that when the surface of the substrate after a reaction using a relatively lower hydrocarbon as a carbon source was observed with a scanning electron microscope, an average diameter of Carbon cilia with a length of 10 μm or less and an average length of 100-150 μm were densely grown.

In other words, carbon cilia having the form and specifications of the present invention cannot be densely grown on the surface of various carbon substrates by conventional methods, but the method of the present invention can be achieved by thermally decomposing hydrocarbons in the coexistence of sulfur or sulfur compounds. It has become possible to grow dense carbon cilia with specific shapes and specifications.

There are no restrictions on the type of hydrocarbon used as a carbon source under the production conditions of the present invention, including methane, ethane, acetin/
Various hydrocarbons are used, ranging from aliphatic hydrocarbons such as , ethylene, and propylene to aromatic hydrocarbons such as benzene, toluene, cyclohexane, naphthalene, and anthracene. It's convenient. Generally, halogen has an inhibitory effect on the growth of carbon fibers, so it is desirable to use a hydrocarbon that does not contain halogen.

There are no particular conditions to limit the type of carbon substrate used in the present invention, but when the sea bile carbon fine particles of the present invention are used as a reinforcing material for composite materials, the carbon substrate may be a carbon substrate such as glassy carbon. Suitable are hard carbon, such as activated carbon powder, or various thermosetting resins such as carbonic acid resin, particularly carbonized powder obtained by firing fine particles of melphonated polystyrene at high temperatures.

At this time, with carbon materials containing sulfur, it is not necessary to add metal particles such as iron or non-metal particles such as silicon as a support, but with carbon substrates that do not contain sulfur, these particles are added as a support and at the same time, the material is carbonized. It is effective to mix and add sulfur or a sulfur compound to hydrogen gas.

It goes without saying that these particulate additives may be added in the form of a fine powder or in the form of a vapor of a metal carbonyl or organometallic compound mixed into the raw hydrocarbon gas.

A scanning electron micrograph of a cross section of a carbon substrate on which the carbon cilia of the present invention are formed shows that the carbon cilia are not directly formed on the surface of the carbon substrate, but are instead of precipitated carbon deposited on the substrate. It shows that the layer is grown to a thickness of 2-5 μm. Since no pores were observed between this precipitated carbon layer and the substrate, it is considered that the adhesion of the carbon cilia to the carbon substrate has sufficient strength for practical use. In addition, a cross-sectional photograph of the carbon cilia itself shows that the carbon cilia consist of regularly concentric carbon layer planes parallel to the fiber axis, and the interlayer distance (l
oo2 is 3.46 to 3.48^.

Since the length of the carbon cilia of the present invention is usually about several tens of micrometers, its tensile strength and elastic modulus cannot be measured with a common tensile tester, but in general, the strength of carbon fibers increases as the diameter becomes smaller. Since the carbon cilia of the present invention exhibits a tendency to increase exponentially, the carbon cilia of the present invention with an average diameter of several micrometers have a higher strength than the relatively large and long carbon fibers with a relatively large diameter produced on a general substrate by a conventional method. It is inferred that it exhibits excellent tensile strength and elastic modulus.

It is clear that the carbonaceous sea bile particles of the present invention have a larger surface area per unit weight, that is, a larger specific surface area than carbon particles of the same weight. In addition, the aggregate has an appropriate porosity without being tightly packed, and can be used as a support for various metal catalysts to improve catalytic activity and facilitate catalytic reactions. It is a material suitable for various uses such as door materials. In this way, a carbon material with a special shape that can exhibit unique performance is a completely new and completely unknown material.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Example-1 5% divinylbenzene and styrene copolymer fine grain 4
Add a mixture of 1130 ml of fuming sulfur containing 60 g of 17 K So and 30 mJ of sulfuric acid and heat at 90°C with stirring.
Allowed time to react. The obtained sulfonated polystyrene was heated in a porcelain reaction tube under nitrogen gas flow at a heating rate of 1°C/min.
The temperature was raised to 1000°C and held for 5 hours to perform firing and carbonization. (
Figure 1) The particle size obtained in this way is 90-140.
μm hard carbon has sulfur 3.33wt% and ash content 0-05
According to fluorescence X-ray analysis and atomic absorption spectrometry, the ash content was mostly Si and p, and no Fe was detected. A mullite boat (width 16 mm,
(length 150mm), inner diameter 25m5 length 1ooO+
After inserting the tube into the center of a quartz reaction tube, the tube was kept at 1000° C., and a propylene gas mixture having a concentration of 25 vol. 1% was supplied together with hydrogen gas at a rate of 4 oml/min. After 2 hours, sea bile-like carbon fine particles as shown in FIG. 2 were obtained. The average production density of carbon cilia densely grown on the surface of these fine particles is 400 to 450 cilia per particle (13,000 to 14,000 cilia per liter of surface area of carbon particles).The average diameter of each fiber is 5.0 μm, and the average length is 120 μm. Met. BE again
Specific surface area of raw carbon fine particles measured by T method: 10-1
5 d/9 is about 60 rr after carbon cilia are packed? /g
It increased to

Example 2 A commercially available sulfo/group-containing cation exchange resin (Amberly Ii'L-120) was converted into hydrogen form and calcined under the same conditions as Example 1 in a nitrogen gas atmosphere to obtain a The hard carbon with a grain size of 500 to 600 μm (Figure 3) contains sulfur 2.
It contained 89 wt tchi and ash content 0.10 tc, and no iron content was detected in the ash. Propylene was flowed over the carbon particles to generate carbon cilia under the same operation and conditions as in Example 1. As shown in FIG. 4, sea bile-like carbon fine grains with cilia having an average diameter of 4.6 μm, a length of 9-0 μm, and a production density of 500 to 550 cilia/grain (650 cilia/-) were obtained.

Reference example-1 C manufactured by Kureha Chemical Industry Co., Ltd. with a particle size of 130 to 170 μm
arbon mlcro balloon (Figure 5) is a soft carbon particle with a small sulfur content of 0.88 wt%, unlike the carbon particles used in Examples 1 and 2.
The ash content was 0.65 wt% and no iron was detected.

Propylene was flowed over these carbon particles under the same operation and conditions as in Example 1, but as shown in Figure 6, the particle surfaces were only covered with film-like and soot-like carbon, and no carbon cilia were observed. There wasn't.

Example 3 The activated carbon fine powder manufactured by Wako Tsumugi Co., Ltd. was used as the carbon substrate, and benzene vapor was used as the hydrocarbon to form dense carbon cilia. The results are shown in FIG. First, the activated carbon was crushed and sieved, and the fine particles having a particle size of 500 to 1200 μm were washed with a mixed solution of concentrated hydrochloric acid and hydrofluoric acid (1:1) to sufficiently remove impurities.

Next, the activated carbon particles were immersed in a 0.5 mol/l ferric nitrate solution, separated and dried, and further soaked in a hydrogen atmosphere for 5 mol/l.
Heat treatment was performed at 00°C for 1 hour and at 1100°C for 1 hour. Through this treatment, iron-supported activated carbon with an iron content of 0.82 wt% was obtained. The particle size distribution of iron in this case is 330-1
100^ (average particle size is 660^).

Using this iron-supported activated carbon (0.29 g) as a carbon substrate, carbon cilia were produced using substantially the same equipment and operation as in Example 1. However, using benzene vapor as the hydrocarbon,
．． 1 vat%, hydrogen 85.4 vol%, H2S
A mixed gas of 2-5 vol % was supplied onto the carbon substrate at a flow rate of 40 il/min, and thermal decomposition was performed at 1100° C. for 30 minutes. As shown in Figures 7 and 8, there are 5 to 5 carbon cilia with a fiber diameter of 0.1 to 2 μm and a length of several 100 μm.
A chestnut-shaped dispersion reinforced material was obtained which was produced at a very high production density of 10 x 10' pieces/-.

Reference Example-2 Example 3 and activated carbon fine particles were not impregnated with iron, and the activated carbon fine particles from which impurities were removed were used as a carbon base as they were, and H2
401 liters of hydrogen gas containing 12.1 vol 1% of hydrogen gas without adding S! Pass through at a flow rate of /min 1
When thermally decomposed at 100°C for 30 minutes, fibers with a larger diameter of 10 to 15 μm1 were found on the surface of activated carbon particles compared to Example 3.
Carbon fibers with a length of 1 to 5 crn were produced at a very low density of 20 to 40/-, and the entire surface of the activated carbon was not covered with carbon cilia.

Next, the activated carbon fine particles impregnated with 0.82 wt% iron of Example 3 are used as a carbon base, and H3S is added in the same manner. knee
t'l < 12. Hydrogen gas with a benzene concentration of l vol '4 was passed through at a flow rate of 4 Q mJ/min.
Pyrolysis was carried out at °C for 30 minutes. In this case, the density of carbon cilia produced was approximately twice as high as that in the case where no iron was impregnated, but similarly it was not possible to grow them densely enough to cover the entire surface of the activated carbon.

[Brief explanation of the drawing]

Figure 1 is a scan of the fine carbon particles used as the raw material in Example 1, and Figure 2 is a scan of one sea bile-like carbon fine particle obtained by thermally decomposing propylene on the fine carbon particle shown in Figure 1 and densely covered with carbon cilia. Electron micrograph. Figure 3 is a scan of the fine carbon particles that were the raw material used in Example 2, and Figure 4 is a scan of one sea bile-like carbon particle obtained by thermally decomposing propylene on the fine carbon particle in Figure 3 to form dense carbon cilia. Electron micrograph. FIG. 5 is a scanning electron micrograph showing the state when propylene is thermally decomposed on the fine carbon particles of the raw material used in Reference Example 1, and FIG. 6 is a photograph showing the state when propylene is thermally decomposed on the fine carbon particles of FIG. FIG. 7 and FIG. 8 are scanning electron micrographs of the cone-shaped carbon fine powder obtained by thermally decomposing benzene on the activated carbon fine powder of Example 3 and densely growing carbon cilia.

Claims (1)

[Claims] Carbon powder densely populated with micro carbon cilia, characterized in that micro carbon cilia with an average diameter of 10 μm or less are produced on the surface of spherical or non-spherical micro carbon powder at a high density of 9,100 or more per surface area. body.