POLYETHYLENE NAPHTHALATE FIBER AND METHOD FOR PRODUCTION THEREOF

摘要

Disclosed is a polyethylene naphthalate fiber for use as an industrial material showing less fatigue in a complex. The polyethylene naphthalate fiber comprises an ethylene-2,6-naphthalate unit in an amount of 80% or more and has a strength of 6 cN/dtex or more or an elongation at secondary yield point of 8% or less. Also disclosed is a method for producing the polyethylene naphthalate fiber by melting and stretching polyethylene naphthalate to produce a fiber, and stretching the fiber, which is characterized by conducting the pre-stretching at a fiber temperature of 80 to 120°C and a pre-stretch tension of 0.05 to 0.3 N/dtex, conducting a first stretching at a fiber temperature of 130 to 180°C and a drawing tension of equal to or lower than the prestretch tension, repeating the stretching until the draw ratio reaches 5 times or greater, and finally conducting heat stretching at a stretch ratio of 0 to 2%.