Patent ID: 6852411

Claim:
A polyester fiber comprising polyethylene terephthalate at 90 mol % or higher of a whole repeating unit in a molecular chain thereof, the fiber having an intrinsic viscosity (IV) of 0.85 dl/g or higher and simultaneously meeting the following characteristics: (a) strength 6.0 cN/dtex; (b) strength×(breaking elongation) 0.5 24.0 cN/dtex. % 0.5 ; (c) monofilament linear density≦5.0 dtex; (d) main dispersion peak temperature of loss tangent (tan δ) in the measurement of dynamic viscoelasticity at 110 Hz≦147.0° C. and (e) a birefringence of an undrawn yarn>0.08.