Patent ID: 6160085
Filing Date: 2000-12-12
Classification: C08G,C08L

Abstract:
A polyester comprising:1) a polymer structure comprising ethylene terephthalate units as the main component of the polymer;2) an intrinsic viscosity ranging from 0.6 to 0.9 dl/g as determined on the basis of relative viscosities measured from solutions having various concentrations prepared by dissolving a 0.25 g sample of the polymer dissolved in a solvent of 1:1 weight ratio of phenol to tetrachlorethane at 30.degree. C. in an Ubbelohde capillary viscosity tube;3) an antimony content of 0.8 to 2.0 mmol/kg;4) a temperature-rising crystallization peak temperature (Tc.sub.1) of at least 160.degree. C., and a temperature-dropping crystallization peak temperature (Tc.sub.2) of at most 170.degree. C. or non-existent, and5) a structure in which the polyester is constituted of spherulites of polyester in a number (N.sub.1) and a number (N.sub.2), wherein upon heating a specimen of the polyester from room temperature to 120.degree. C. and maintained for 10 minutes at the elevated temperature, the number (N.sub.1) of spherulites is at most 1.times.10.sup.-2 /.mu.m.sup.2 and upon cooling of a heated polyester specimen from 300.degree. C. to 200.degree. C. and maintained at 200.degree. C. for 2 minutes, the number (N.sub.2) of spherulites is at most 1.times.10.sup.-3 /.mu.m.sup.2.