PURPOSE: To mass-produce carbon yarn having high performance at high speed by making acrylic precursor yarn containing a specific amount of boron (compound) flameproof by a flameproofing furnace of repeatedly heating and cooling and then carbonizing.
CONSTITUTION: Acrylic precursor yarn containing 0.01-10wt.% boron (compound) (preferably boric acid) is made flameproof by a flameproofing furnace of repeatedly heating and cooling in an oxidizing atmosphere (preferably in air) at 10-30 minutes and then carbonized in an inert atmosphere to give the objective yarn. The flameproofing furnace is divided into a zone to store rollers of transporting and cooling the precursor yarn and a zone of heat treating except an opening part to pass the precursor yarn and the rollers are preferably rollers which are cooled to 10-80°C lower than a heated atmosphere by introducing air into shafts and exhausting from the side of the rollers.
DAIGUUJI TSUTOMU
UNO HIROBUMI
