Patent ID: 7163742

Claim:
A polytrimethylene terephthalate preoriented yarn package, comprising preoriented yarn formed of poly (trimethylene terephthalate) having an intrinsic viscosity of from 0.7 to 1.3 dl/g and having at least 95 mole % of trimethylene terephthalate repeating unit and 5 mole % or less of another ester-repeating unit, and that is accumulated to form a layer of wound yarn weighing 2 kg or more and satisfying the following conditions (1) to (4): (1) a difference in diameter between edge portions of the package and a middle portion being in a range from 0 to 5 mm; (2) a difference in thermal shrinkage of the yarn accumulated at the edge portions and that of the yarn accumulated at the middle portion of the package is 0.01 cN/dtex or less; (3) a U % value, a variation in yarn size measured while the preoriented yarn is unreeled from the package is 1.5% or less, and a variation coefficient of period of yarn size variation is 0.4% or less; and (4) the preoriented yarn has a heat of crystallization of 10 J/g or less as measured by a differential scanning calorimetry and a crystalline orientation degree of from 80 to 95%.