To provide a method for efficiently producing a nonconventional polylactic acid fiber exhibiting excellent high-temperature mechanical properties by new structure.
The method for producing the polylactic acid fiber comprises, in drawing a polylactic acid undrawn yarn having ≥6 nm crystal size, carrying out the drawing at ≥85°C draw temperature at ≥120°C heat treatment temperature at the draw ratio (DR) of the following range of 0.90+(elongation of the undrawn yarn/100%)≤DR≤2.0+(elongation of the undrawn yarn/100%). The method for producing the polylactic acid fiber comprises, in drawing a polylactic acid undrawn yarn having <6 nm crystal size, carrying out the drawing at ≥110°C draw ratio at ≥120°C heat treatment temperature at the draw ratio (DR) of the following range of 0.90+(elongation of the undrawn yarn/100%)≤DR≤2.0+(elongation of the undrawn yarn/100%).
SAKAI TAKAAKI
MAEDA YUHEI
