PURPOSE: To obtain pitch-based flexible carbon fiber, having respective specific tensile elastic modulus and compressive breaking strain, excellent in handleability and suitable as prepreg, etc.
CONSTITUTION: Pitch-based carbon fiber, obtained by preferably melting pitch for spinning, spinning the melt through a nozzle having ≥0.5mm diameter at ≤1000P spinning viscosity, annealing the spun fiber at a temperature 40-100°C lower than the softening point for 1-24hr in an inert gas, infusibilizing the fiber and then heat-treating the infusibilized fiber in an inert gas and having ≥40tonf/ mm2 tensile elastic modulus and a positive value of a differential coefficient {d[R()-R(0)]/R(0)}/d for the rate of change in R() {[R()-R(0)]/R(0)} with respect to at 0-0.05% when the electrical resistance in applying a compressive strain in R().
HIGUCHI MASAKAZU
FURUYAMA MASATOSHI
TOMIOKA NORIO
NIPPON STEEL CHEMICAL CO
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