Patent ID: 6982118

Claim:
Polyester pre-oriented conjugate fiber of either a side-by-side or an eccentric sheath/core configuration in which two kinds of polyester components are adhered to each other to form a single filament, wherein at least one of the components consisting of the single filament is polytrimethylene terephthalate containing repeating units of trimethylene terephthalate of 90 mol % or more, and wherein the pre-oriented conjugate fiber is wound to form a package and satisfies the following items (1) to 5: (1) a stretching elongation Vc prior to being treated with boiling water is less than 20%, (2) an elongation at break is in a range from 60 to 120%, (3) a dry heat shrinkage stress value is in a range from 0.01 to 0.15 cN/dtex, (4) the difference in dry-heat shrinkage stress value between the conjugate fibers layered in the selvage portion and the central portion of the package is 0.05 cN/dtex or less, and (5) a yarn fineness variation value U% is 1.5% or less and a variation coefficient of a yarn fineness variation period of 0.4 or less.