Composite fiber having favorable post-treatment processibility and method for producing the same

Abstract

The present invention provides a polytrimethylene terephthalate composite fiber characterized in that the composite fiber is a plurality of single filament which comprises two kinds of polyester components laminated to each other in a side-by-side manner or an eccentric sheath-core manner, at least one polyester component is polytrimethylene terephthalate and the composite fiber satisfies the following conditions: the content of trimethylene terephthalate cyclic dimer in polytrimethylene terephthalate is 2.5 wt % or less, the fiber-fiber dynamic friction coefficient is from 0.2 to 0.4, the degree of intermingling is from 2 to 60 point/m and/or the number of twists is from 2 to 60 T/m and the fiber size fluctuation U% is 1.5% or less.

Dependencies are inferred from the claim text.