POLYESTER THICK-AND-SHIN YARN AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a polyester thick-and-thin yarn capable of imparting the difference of heat shrinkage to space between undrawn part and drawn part and forming a fabric expressing hand feeling characteristic of thick-and-thin thin yarn, e.g. swelling feeling, stiffness or fine crepe while keeping levelness in apparent dyeing state. SOLUTION: This polyester thick-and-thin yarn distributes undrawn part in a range of 0.5 to 50 numbers per cm in the length direction of each monofilament and has <=0.15vol.% uneven dyeing of yarn and <=1.5% uneven fineness of yarn. The yarn is obtained by subjecting a polyester multifilament undrawn yarn having >=12×10<-3> but <=50×10<-3> birefringence to false twisting in draw ratio of >=-1.03 but <=+1.30 at <=120 deg.C heater temperature and then drawing the twisted yarn at a glass transition temperature of the undrawn yarn finally in a draw ratio smaller than a natural draw ratio.