Chemistry of inorganic compounds – Carbon or compound thereof – Elemental carbon
Reexamination Certificate
2002-10-15
2003-11-04
Le, H. Thi (Department: 1773)
Chemistry of inorganic compounds
Carbon or compound thereof
Elemental carbon
C423S447100, C423S447400, C423S447900, C428S304400, C428S313300
Reexamination Certificate
active
06641792
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a hollow carbon fiber, a hollow carbon particle, a production method thereof, and composite of the fiber and resin.
The hollow carbon fiber represented by a carbon nano-tube is several nm to several hundred nm in diameter and several nm to several dozen nm in length, and the wall thereof is cylindrical in form and is made of several to several dozen graphite walls (layers).
Such a hollow carbon fiber has attracted attention for such conspicuous characteristics as mechanical strength, hydrogen storage properties and electric field discharge properties, and studies have been made on its practical application.
Japanese Patent NO. 2845675 discloses a method in which carbon is coagulated subsequent to its evaporation by arc discharge in an inactive atmosphere; Japanese Application Patent Laid-Open Publication NO. 109310/2000 discloses a method in which at least one of X-rays, microwaves and ultrasonic waves are applied to carbon material including —C° C— and/or —C═C—; and Japanese Application Patent Laid-Open Publication NO. 95509/2000 discloses a method wherein a carbon nano-tube is made to grow by contact between carbon vapor and a non-magnetic transition metal.
In any of these production methods, however, the yield of the intended carbon nano-tube is low, and the by-product of carbonaceous material similar to carbon black and amorphous carbon cannot be avoided. When a metallic catalyst is used, it is necessary to refine the reaction products, and a metallic catalyst cannot be removed completely by refining, with the result that the aforementioned hydrogen storage properties and electric field discharge properties are reduced. Such disadvantages cannot be avoided in the prior art.
Further, the aforementioned production methods are practically incapable of controlling the number of wall layers, the diameter and the length of the hollow carbon tube represented by a carbon nano-tube. It has been very difficult to attain a uniform shape and uniform characteristics.
A hollow carbon particle represented by fullerene is several nm to several hundred nm in diameter, and the wall comprises several nm to several dozen graphite layers, including a five-membered ring or seven-membered ring.
Hollow carbon particles have attracted attention for such conspicuous characteristics as mechanical strength, hydrogen storage properties and electric field discharge properties, and studies have been made on its practical application. In the conventional method of its production, carbon is coagulated subsequent to its evaporation by arc discharge in an inactive atmosphere, and it is then separated and refined.
However, the yield of fullerene is low, and the by-product of carbonaceous material similar to carbon black and amorphous carbon cannot be avoided. Further, separation and refining using a solvent, such as benzene, are essential, and a remarkable reduction in productivity has been unavoidable.
Further, the aforementioned production methods are practically incapable of controlling the number of wall layers, the diameter and the length of the hollow carbon particles represented by fullerene.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems involved in the aforementioned known method of production of a hollow carbon fiber represented by a carbon nano-tube obtained therefrom, and hollow carbon particles.
The present invention provides a method of manufacture of a hollow carbon fiber and a hollow carbon particle, which allows the number of wall layers, the diameter and the length of the hollow carbon particles to be controlled, and ensures a uniform shape and uniform characteristics.
What is more, the present invention provides a hollow carbon fiber and its method of production, characterized by comparatively easy mass production, since it does not use a metallic catalyst; hence, it does not require a step of refining and elimination thereof.
The present invention also provides a hollow carbon fiber and its method of production, characterized by comparatively easy mass production with almost no generation of by-products, separation or refining by a solvent.
The following is a summary of aspects of the present invention:
(1) A method of production of a hollow carbon fiber comprising a step of baking and carbonization of polymer particles having a volume of 100 mm
3
or smaller after deforming.
(2) A method of production of a hollow carbon fiber according to the aforementioned aspect (1), characterized by deforming the aforementioned polymer particles by heating.
(3) A method of production of a hollow carbon fiber according to the aforementioned aspect (1) characterized by deforming polymer particles with mechanical force.
(4) A method of production of a hollow carbon fiber according to the aforementioned aspect 1, characterized by deforming polymer particles using irradiation of electromagnetic waves.
(5) A method of production of a hollow carbon fiber according to the aforementioned aspect (1), characterized by deforming polymer particles by any one or a combination of the methods described according to the aforementioned aspects (2) to (4).
(6) A method of production of a hollow carbon fiber according to the aforementioned aspect (1), characterized in the fact that the diameter of a polymer particle is 5 to 5000 times that of a hollow carbon fiber as a final product.
(7) A method of production of a hollow carbon fiber according to aspect (1), characterized in the fact that one or both ends of the fiber are closed.
(8) A method of production of a hollow carbon fiber according to aspect (1), characterized in the fact that the aspect ratio (length/diameter) of the fiber is 1 or more.
(9) A method of production of a hollow carbon fiber according to aspect (1), characterized in that the diameter and length of a fiber are controlled by the volume of polymer particles.
(10) A method of production of a hollow carbon fiber according to aspect (1), characterized by a step of producing polymer particles by a combination of polymers disappearing due to thermal decomposition and carbon precursor polymers.
(11) A method of production of a hollow-carbon fiber according to aspect (10), characterized by a step of producing a micro-capsule from polymers disappearing due to thermal decomposition and carbon precursor polymers, and baking the aforementioned micro-capsule subsequent to melting and spinning.
(12) A method of production of a hollow carbon fiber according to aspect (10), characterized in the fact that the difference between the softening temperature of polymers disappearing due to thermal decomposition and that of carbon precursor polymers does not exceed 100 degrees Celsius.
(13) A method of production of a hollow carbon fiber according to aspects (10) or (11), characterized in the fact that the ratio between inner and outer diameters of the aforementioned hollow carbon fiber is controlled by a ratio of the thickness between the layer of polymers disappearing due to thermal decomposition and that of carbon precursor polymers.
(14) A method of production of a hollow carbon fiber according to aspects (10) or (11), characterized in the fact that the number of layers of the aforementioned hollow carbon fiber is controlled by a ratio of the thickness between the layer of polymers disappearing due to thermal decomposition and that of carbon precursor polymers.
(15) A method of production of a hollow carbon fiber according to aspects (10) or (11), characterized by using polymers wherein the residual carbon percentage of polymers disappearing due to thermal decomposition does not exceed 10 percent by weight and that of carbon precursor polymers does not exceed 15 percent by weight.
(16) A method of production of a hollow carbon fiber according to aspect (11), characterized in the fact that the aforementioned micro-capsules are prepared by an interfacial chemical technique.
(17) A method of production of a hollow carbon fiber according to aspect (11), characterized in the fact that the aforementioned micro-capsules a
Hirai Osamu
Kokaji Kazumi
Taguchi Noriyuki
Takeda Shinji
Antonelli Terry Stout & Kraus LLP
Hitachi Chemical Company Ltd.
Le H. Thi
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