PITCH MATERIALS

摘要

A pitch material useful for the manufacture of carbon fibres has an optically anisotropic phase content of at least 80% by weight, a pyridine-insoluble matter content of from 30 to 70% by weight, a number average molecular weight of from 1000 to 1400 and a softening point of from 330 to 380 DEG C. This pitch material may be obtained by a two step heat treatment performed on a starting pitch comprising a petroleum-based residual oil freed from light oily matter. The first step is performed at 400 to 460 DEG C under a pressure of 5 to 50 mmHg and the second step is performed at 450 to 500 DEG C for 0.2 to 30 minutes under a pressure of 0.1 to 5 mmHg. The heat treatment is preferably performed in a film evaporator.