PURPOSE: An aromatic polyamide having a specific structural unit and an intrinsic viscosity higher than a specified value is spun and heat drawn at a high ratio to produce the titled fiber used in tire cords, because of its high solubility in solvents, good formability, high strength and high Young's modulus.
CONSTITUTION: An aromatic polyamide consisting of structural units of formula I, II, and III (Ar1, Ar2, and Ar3 are divalent aromatic carbon ring group strethcing bond chains coaxially or in paralley, aromatic heterocyclic ring binding with the ring atoms locating on the maximum interval positions; X is CH2, SO2, CO, S) or of formula I and III wherein the content of formula I is 10W80mol% and formula II is 20W40mol% and the intrinsic viscosity is higher than 20 is made into fiber. Then, the fiber is heat drawn at 300W600°C by more than 4 times the original length to produce the objective fiber of higher than 10g/d tensile strength and higher than 300g/d initial modulus at room temperature.
SASAKI HIDEHARU
MERA HIROSHI
SAWAKI TOORU
AOKI AKIHIRO
