Process for producing carbon fibers having excellent properties

摘要

A process for producing carbon fibers by heat-treating an acrylonitrile fiber, containing or impreganted with an aminosiloxane, at a temperature of at least 150 DEG C for 0.1 second to 30 minutes so that the fiber contains 20 to 80 weight % undissolved matter upon immersing it in a 60% aqueous solution of sodium thiocyanate at 80 DEG C for 20 minutes, and then carbonizing the fiber, whereby the productivity throughout the whole process, including the step of producing the precursor fiber and the step of producing the carbon fiber, is increased and a carbon fiber having high tensile strength and high modulus of elasticity is obtained in an industrially advantageous manner.