Patent ID: 7078096

Claim:
A process for producing a polyester fine false twist textured yarn composed of a polyester and having a single filament fineness of 0.6 dtex or below and a total number of single filaments of 100 to 400 and satisfying the following (i) to (l): (i) a total crime ratio TC of 2 to 5%, (j) a shrinkage percentage in boiling water FS of 2.5 to 4.5%, (k) a breaking strength of 3.0 cN/dtex or above and (l) a breaking elongation of 15 to 45%, 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 and 400 and a birefringence of 0.03 to 0.06 to simultaneous draw-false texturing and producing the false twist textured yarn, the process further comprising subjecting 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.