JPH06680B2 - Carbonaceous whisker manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a carbonaceous whisker, and more particularly to a method for producing a whisker useful as a reinforcing material or a conductive material for various composite materials.

2. Description of the Related Art Since carbonaceous whiskers have high strength and high elasticity, various composite materials have been manufactured by combining them with resin materials, carbon materials, ceramics and the like. It is also known that a carbonaceous whisker is treated at high temperature to form a graphitized product, or various substances are inserted into graphite to form an intercalation compound and used as a conductive material.

As a method of producing such a carbonaceous whisker, a method of vapor-phase pyrolyzing a hydrocarbon in the presence of a transition metal catalyst is known (for example, JP-A-57-117622). However, in such a method, preparation of the catalyst and recovery of the generated whiskers are troublesome and troublesome, and there is a problem that it is difficult to obtain a homogeneous whisker. Furthermore, the carbonaceous whiskers obtained by this method have a concentric carbon hexagonal mesh plane developed parallel to the fiber axis direction, and the tip portion is closed, so that the formation of graphite intercalation compounds is difficult to proceed. It has the drawback of

DISCLOSURE OF THE INVENTION Therefore, the present invention has an object to provide a method capable of easily producing a homogeneous graphite intercalation compound and producing a carbonaceous whisker having properties suitable for use in a composite material in a high yield. did.

Means for Solving the Problems The method for producing a carbonaceous whisker of the present invention which can achieve such an object is to reduce an organosilicon compound or a mixture of an organosilicon compound and a hydrocarbon compound with a reducing compound containing a sulfur compound. Alternatively, in the vapor phase pyrolysis at a high temperature in the presence of an inert carrier gas, the molar ratio of silicon to carbon in the system is less than 0.1 and 0.005 or more, and the pyrolysis temperature is 120.
It is characterized in that the linear velocity of the gas in the reaction zone is set to 0 to 1400 ° C. and 10 cm / min or less.

As the organosilicon compound used as a raw material in the present invention, silanes or siloxanes having a silicon-carbon bond are used. Of these, examples of silanes include alkyl-substituted silanes such as triethylsilane, tetraethylsilane, and hexamethyldisilane, alkoxy-substituted silanes such as tetramethoxysilane and tetraethoxysilane, and aromatic-substituted silanes. Examples thereof include hexamethyldisiloxane, dimethylpolysiloxane, and methylphenylpolysiloxane. In addition to these, silanols such as trimethylsilanol, alkoxy-substituted siloxanes, and the like can be used, and mixtures or derivatives thereof can also be used as long as they can be gasified.

In the present invention, as the hydrocarbon compound mixed with the organosilicon compound and used as a raw material, aliphatic hydrocarbons such as methane, ethane, propane, etc., and aromatic hydrocarbons such as benzene, toluene, etc. are used. For example, it does not matter if other elements such as oxygen are included.

The sulfur compound used in the present invention behaves as a catalyst, and for example, hydrogen sulfide, mercaptans such as methyl mercaptan, ethyl mercaptan and toluenethiol, or thioethers such as diethyl sulfide and thiophene can be used. When the sulfur compound is an organic sulfur compound, it can be used by substituting a part or all of the above-mentioned hydrocarbon compound as a raw material. Further, when the sulfur compound is an organic compound containing silicon, it can be used by substituting it for at least a part of the above-mentioned organic silicon compound as a raw material. As an example of such a catalyst, for example, δ-mercaptopropyl triamine is used. Examples thereof include mercapto-modified silanes such as methoxysilane and mercapto-modified polysiloxane.

The carrier gas used in the present invention is a reducing or inert gas, and examples thereof include hydrogen, nitrogen, and argon. Among them, hydrogen is preferably used.

In the present invention, an organosilicon compound as a raw material or a mixture of the same and a hydrocarbon compound is sent to a high temperature reaction zone by a carrier gas together with a catalyst. At this time, the moles of silicon and carbon contained in the reaction gas are mixed. Ratio less than 0.1
It must be 0.005 or more. That is, when the molar ratio is 0.1 or more, silicon carbide whiskers are produced, and carbonaceous whiskers with high purity cannot be obtained. If the molar ratio is less than 0.005, more soot is produced and the whisker yield is low.

The amount of the sulfur compound used as a catalyst is not particularly limited, but if the amount is too large, the concentration of the raw material is limited. Therefore, an effective amount of 10% by volume or less, preferably 5% by volume or less in the reaction mixture is effective. It is desirable to have the amount delivered with the carrier gas or feed so that it is evenly present in the reaction mixture.

The thermal decomposition reaction in the present invention is carried out at 1200 to 1400 ° C. As a device therefor, for example, a horizontal electric furnace provided with a heat-resistant reaction tube of alumina or the like can be used, but the device is not necessarily limited to such a device.

Example 1 To an electric furnace equipped with a reaction tube having an inner diameter of 70 mm and a length of 1000 mm, hydrogen containing 3% by volume of hydrogen sulfide as a catalyst was supplied at a rate of 200 cc / min, and tetramethyldisiloxane was used as a raw material. Benzene has a Si / C molar ratio of 0.
The mixture was mixed so as to be 03, and this was supplied at a rate of 1.3 cc / hr to the evaporation section (temperature 150 ° C.) of the reaction tube. The vaporized raw material thus mixed with the carrier gas flows through the reaction tube at a rate of 205 cc / min (that is, a linear velocity of 5.3 cm / min),
It is pyrolyzed at 0 ℃ and after 1 hour of reaction, the length is 1mm.
Then, 1 g of carbonaceous whiskers having an average diameter of 0.6 μm was obtained. The gap d of the carbon hexagonal mesh surface of the obtained carbonaceous whisker
₀₀₂ , and the crystal size L _c in the C-axis direction are as shown in Table 1, and the angle formed between the crystal plane and the fiber axis is about 29.
It was °.

Example 2 The same apparatus as in Example 1 was used, except that hexamethyldisilazane and benzene were mixed as a raw material so that the Si / C molar ratio was 0.03.
When reacted for a time, the length is 1 mm or less, the average diameter is 1.0 μm
As a result, 1.2 g of carbonaceous whisker was obtained.

Comparative Example 1 A similar vaporization raw material was thermally decomposed under the same conditions as in Example 1 except that a reaction tube having an inner diameter of 22 mm and a length of 1200 mm was used. The linear velocity of the gas at this time was about 21 cm / min, soot was generated in a large amount, and only a small amount of the polymorphic whiskers was obtained.

Comparative Example 2 The reaction was carried out for 2 hours in the same manner as in Example 1 except that the thermal decomposition temperature was 1050 ° C., and 1 g of carbonaceous whiskers having a length of 5 to 30 mm and an average diameter of 15 μm was obtained.

The d ₀₀₂ and L _c of this whisker are also shown in Table 1. The crystal plane and the fiber axis were almost parallel.

From the values in Table 1, it can be seen that the carbonaceous whiskers according to the present invention are significantly crystallized.

Furthermore, regarding the carbonaceous whiskers of Example 1 and the carbonaceous whiskers of Comparative Example, 30 at 3000 ° C. under an argon gas atmosphere.
0.0025 g of these graphitized whiskers were used as a positive electrode material of a lithium secondary battery in which lithium perchlorate dissolved in propylene carbonate was used as an electrolyte and lithium was used as a negative electrode material, and charged at 2 mA for 150 minutes. After that, the discharge electric quantities were compared.

As a result, the amount of electric discharge when 2 mA discharge was performed until the discharge voltage dropped from 5.5 V to 5.3 V was 80 coulombs per 1 g of carbon in the whiskers of the comparative example, whereas the whiskers of Example 1 were Since it is 270 coulombs per 1 g of carbon, it can be seen that the activity of the carbonaceous whiskers obtained by the method of the present invention is remarkably high.

Effects of the Invention According to the method for producing a carbonaceous whisker of the present invention, there is an advantage that a carbonaceous whisker suitable as a reinforcing material or a conductive material for a composite material can be efficiently produced.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masahiro Kanda, 252 Kawashimada, Gotemba, Shizuoka Prefecture, Yazaki Parts Co., Ltd. (72) Inventor, Hitoshi Ushijima, 252, Kawashimada, Gotemba, Shizuoka, Co., Ltd. (56) References, JP 60-6054999 (JP, A)

Claims (1)

[Claims] 1. In the system for the gas phase pyrolysis of an organosilicon compound or a mixture of an organosilicon compound and a hydrocarbon compound at high temperature in the presence of a reducing or inert carrier gas containing a sulfur compound, The molar ratio of silicon to carbon is less than 0.1 and 0.005 or more, and the thermal decomposition temperature is 1200 to
A method for producing a carbonaceous whisker, wherein the temperature is set to 1400 ° C. and the linear velocity of gas in the reaction zone is set to 10 cm / min or less.