| 摘要 |
PROBLEM TO BE SOLVED: To obtain a highly oriented undrawn polyester yarn having high orientation suppressing effect on polyester molecular chain in spinning, improved productivity, suppressed deterioration with time and excellent processing stability in false-twisting work by setting the storage modulus and the intrinsic viscosity(IV) to respectively specific levels. SOLUTION: The objective polyester yarn has a storage modulus of >=7.0×103 dyn/cm2 determined by the measurement of dynamic viscoelasticity at 250 deg.C and 2 Hz and an IV of 0.55-0.80. The highly oriented undrawn yarn has a diffraction peak characteristic to polyester by wide-angle X-ray diffraction, a birefringence of 25×10-3 to 70×10-3, a hot water shrinkage of <=30% at 70 deg.C and an aluminum content of 5-500 ppm in terms of aluminum atom. The highly oriented undrawn yarn can be produced by spinning a polyester composition incorporated with a compound of formula Al[OR1]l[OR2]m[OR3]n[R4]o (R1 to R3 are each an alkyl, an aryl or the like; R4 is an alkylacetoacetate ion or the like; (l), (m), (n) and (o) are each zero or a positive number and the sum is 3) at a spinning speed of 3,500-7,000 m/min.
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