Synthetic fibers

Abstract

The present disclosure relates to a synthetic fiber, having a loss tangent peak temperature of 100° C. or higher and 150° C. or lower, a loss tangent peak value of 0.15 or more, and a dry heat shrinkage of 5% or more and less than 15%. The present disclosure also relates to a synthetic fiber, having a loss tangent area from 30° C. to 130° C. of 4.0° C. or more and 7.5° C. or less.

1 . A synthetic fiber, having a loss tangent peak temperature of 100° C. or higher and 150° C. or lower, a loss tangent peak value of 0.15 or more, and a dry heat shrinkage of 5% or more and less than 15%. 
     
     
         2 . The synthetic fiber according to  claim 1 , having a loss tangent area from 30° C. to 130° C. of 4.0° C. or more and 7.5° C. or less. 
     
     
         3 . The synthetic fiber according to  claim 1 , wherein when a fiber cross section after dyeing to have an L* value of 20 or less is displayed as a 256-level grayscale image, an absolute value of a difference between an average pixel value of a circle that is concentric with a center of an inscribed circle and that has an area of 10% of an area of the fiber cross section and an average pixel value of an outer peripheral portion that has an area of 10% of the area of the fiber cross section is 15 or less. 
     
     
         4 . The synthetic fiber according to  claim 1 , having the loss tangent peak temperature of higher than 120° C. and 150° C. or lower. 
     
     
         5 . The synthetic fiber according to  claim 1 , having the loss tangent peak temperature of 123° C. or higher and 150° C. or lower.