| 摘要 |
The invention relates to a vapor grown carbon fiber having a mean fiber diameter of 80 to 500 nm, an aspect ratio of 100 to 200 and preferably a bulk density of 0.02 g/cm<SUP>3 </SUP>or less, wherein filaments having a diameter within ±20% the mean fiber diameter occupies 65% (on a number basis) or more of the total. The production method involves thermal decomposition of a carbon source at 800 to 1,300° C. in the presence of, as a catalyst, a transition metal compound having a vapor pressure of 0.13 kPa (1 mmHg) or more at 150° C. and spraying of the carbon source and the transition metal compound in gas form toward the reactor inner wall to allow reaction to proceed. The vapor grown carbon fiber having a larger aspect ratio has excellent dispersibility, and when added in a resin, a smaller amount contributes to enhancement in electroconductivity and thermal conductivity, as compared with a case using conventional one.
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