Method of preparing polyester fiber for seat belt
Disclosed is a high strength polyester fiber for a seat belt, and in particular, a polyester fiber for a seat belt, which has intrinsic viscosity of 0.8 to 1.5 dl/g, tensile strength of 8.8 g/d or more, and total fineness of 400 to 1800 denier. A method of preparing the fiber is disclosed. The polyester fiber includes filaments having high strength, low modulus, and high elongation to significantly lower shrinkage, while securing excellent mechanical properties, it is possible to manufacture a seat belt having excellent impact absorption and significantly improved abrasion resistance and heat resistant strength retention, even with a woven density of 260 yarns/inch or less.
1. A method of preparing a polyester fiber for a seat belt:
melt spinning a polyester polymer having intrinsic viscosity of 0.8 dl/g or more at 270 to 310° C. to produce undrawn polyester yarn; and
drawing the undrawn polyester yarn;
wherein the drawing process is carried out after passing the undrawn yarn through a godet roller so that an oil pickup amount is 0.3% to 0.7%;
a first draw ratio is 3.5 to 4.5 and a second draw ratio is 0.9 to 1.8 in the drawing process; and
a first godet roller is operated at a temperature of 60 to 80° C. at a speed of 500 to 540 m/min, a second godet roller is operated at a temperature of 80 to 100° C. at a speed of 550 to 590 m/min, a third godet roller is operated at a temperature of 110 to 130° C. at a speed of 1800 to 2000 m/min, and a fourth godet roller is operated at a temperature of 160 to 180° C. at a speed of 2800 to 3000 m/min, in the drawing process.
2. The method according to claim 1 , wherein the oil pickup amount is 0.35% to 0.7%.