Process for producing textured polyester yarn

Claim 1

In a process for producing textured textile yarn fron undrawn continuous filament yarn by first drawing the yarn without texturing the yarn and then air-jet texturing the drawn yarn to form a bulky yarn having crunodal surface loops; the improvement for producing polyester textured yarn having a boil-off shrinkage of less than 3.5 percent without heating the yarn after the yarn is drawn, which comprises continuously feeding to the drawing step a spin-oriented polyester yarn characterized by a break elongation of 70 to 180 percent, a birefringence value of at least 0.025, a crystallinity of less than 30 percent, and a relative viscosity of at least 18, drawing the spin-oriented polyester yarn at 1.3 to 2.0 draw ratio while heating the yarn with a heater at a temperature from 180° to about 210° C and feeding the drawn yarn directly to an air jet at 8 to 35 percent overfeed without additional heating, jet texturing the yarn with the air jet to form crunodal surface loops in the yarn, and packaging the resulting textured yarn at a package speed (P) greater than the take-off speed (T) from the air jet, the value of (T-P)/P (100) being from -1 to -10 percent.