PRODUCTION OF HIGH-ELASTICITY POLYESTER FIBER

PURPOSE:A polyester copolymer containing diphenyldicarboxylic acid is melt spun at a specific taking-up speed and drawn to produce the titled fiber suitably used as an industrial material, because of its high Young's modulus, strength and elongation. CONSTITUTION:A polyester copolymer with an intrinsic viscosity of 0.5-1.8, mde from (A) the acid components consisting of 45-75mol% 4,4'-diphenyldicarboxylic acid and 55-25mol% terephthalic acid and (B) the diol components mainly consisting of ethylene glycol is melt spun at a winding-up speed of more than 5,000, preferably more than 8,000m/min to give a yarn of 100-280X10 optical birefringence. Then, the resultant yarn is drawn at a 1.1-4.0 draw ratio to give the objective fiber of 280-400X10 optical firebringence. USE:Tire cored and conveyor belt.