EASILY DYEABLE POLYESTER FIBER

摘要

PROBLEM TO BE SOLVED: To provide flame-retardant polyester fiber that is disperse dye-dyeable at normal pressure and retains stabilized flame retardancy for a long period of time. SOLUTION: This invention relates to easily dyeable polyester fiber yarn constituted with a polyester copolymer fiber that satisfies the following formulas (1) and (2): (1) tanδmax>=0.20, (2) Tα<=125 deg.C (wherein tanδmax means the maximum loss tangent in the measurement of the dynamic viscoelasticity and Tαmeans the temperature at the maximum loss tangent) and the whole surface area of the fiber yarn coming into contact with the dye liquor is >=33 mm2/ m.dtex on the dyeing.