Method for producing polyester extra fine multi-filament yarn and polyester extra fine false twist textured yarn, polyester extra fine multi-filament yarn, and polyester extra-fine false twist textured yarn

摘要

There are provided a process for producing a polyester fine multifilament yarn having a single filament fineness of 0.9 dtex or below, a total number of single filaments of 100 to 400 and a birefringence of 0.03 to 0.06 comprising passing polymer streams of a polyester polymer melt extruded from a spinneret surface through an atmosphere wherein a distance of 0 to 40 mm from the spinneret surface is regulated to a temperature within the range of 100 to 300° C., further cooling the polymer streams and then converging the cooled filaments into a filament bundle at a position of 350 to 500 mm from the spinneret surface; a process for producing a polyester fine false twist textured yarn comprising subjecting a polyester fine multifilament yarn having a single filament fineness of 0.9 dtex or below, a total number of single filaments of 100 to 400 and a bifringence of 0.03 to 0.06 to false twist texturing, the process comprising subjecting the multifilament yarn to air interlacing so as to provide a degree of interlacing of 50 to 90 interlaced spots/m measured for the false twist textured yarn, regulating the residence time in a draw-false twisting heater of 0.052 to 0.300 second and the temperature of the running filament yarn at the outlet of the heater to a higher temperature than the glass transition temperature (Tg) of the polyester polymer by 90 to 140° C., subjecting the multifilament yarn to simultaneous draw-false twist texturing at a draw ratio of 1.40 to 1.70 times, providing the false twist textured yarn, applying a finish oil in an amount of 1.3 to 3.0% by weight based on the weight of the false twist textured yarn and winding the resulting yarn under a winding tension of 0.05 to 0.30 cN/dtex at a speed of 500 to 1200 m/min; and a process for producing the polyester fine false twist textured yarn having a single filament fineness of 0.9 dtex or below, a total number of single filaments of 100 and 400 and a birefringence of 0.03 to 0.06 comprising subjecting a polyester multifilament yarn to the simultaneous draw-false twisting and producing the false twist textured yarn, the process comprising the polyester fine multifilament yarn to air interlacing treatment before and after the simultaneous draw-false twist texturing and regulating the degree of interlacing before and after the latter air interlacing treatment to 30 to 60 interlaced spots/m and 70 to 110 interlaced spots/m, respectively.