Patent ID: 6623681
Filing Date: 2003-09-23
Classification: D01F

Abstract:
A method for producing intermediate yam comprising polyester fibers having the following properties (A):(1) Specific gravity 1.335-1.360, (2) Degree of crystallinity 21-26%, (3) Crystal size in terms of Miller index (010) 1.4-2.2 nm, in terms of Miller index (100) 1.4-2.5 nm and in terms of Miller index (105) 1.6-3.5, (4) Degree of crystal orientation no more than 75% in the 010 plane and no more than 85% in the 105 plane, and (5) Degree of amorphous orientation 0.15-0.4, hot water shrinkage 0 to 35% and dry heat shrinkage 0-35%, which is characterized in that highly oriented undrawn polyester yarn, obtained by melt-spinning at a take-off speed of 2500-3500 m/min, having a birefringance of 20-80Ã—10âˆ’3 is passed under a tension of 0.3Ã—10âˆ’2 g/d to 5.0Ã—10âˆ’2 g/d through a non-contact heater at a heater temperature of at least 250Â° C., and wherein 5 to 40% shrinkage is effected.