Process for preparing non-round cross-sectional polyester yarn

摘要

A method for producing a polyester fiber is provided to improve the degree of non-circular shape and decrease the shrinkage rate of the polyester fiber, by regulating the length of a delay cooling part and the distance between a cold air-ejecting surface and a filament, optimizing a spinneret, and applying super-high speed spinning. A polyester fiber having a noncircular cross-section is produced by using a spinning process of a highly oriented yarn at a spinning rate of no less than 5,000m/min, wherein the polyester fiber has a fineness of 1-5 denier. In producing the polyester fiber, firstly, a polyethyleneterephthalate polymer is melted and spun by using a spinneret having eight slits. The melted and spun stuff is passed through a delay cooling part of no more than 20 mm, and then passed through a cooling part. The delay cooling part is installed rightly below the spinneret. In the cooling part, the maximum distance between a cold air-ejecting surface and a filament is regulated to 2-30 mm. Each slit of the spinneret satisfies the following conditions: 1.2=8ÎC+0.2mm, theta=60‹-120‹, the number of wings is eight, wherein A is a length of a major-axis slit(mm), B is a length of a minor-axis slit of a center part(mm), C is a width of the slit(mm), D is a length of a minor-axis slit of an outer part(mm), and theta is a sloping angle of the minor-axis slit of the outer part with respect to the major-axis slit.