abstract |
A polyethylene naphthalate fiber manufactured by a process comprising the steps of: (A) melt rolling of a solid phase polymerized polyethylene 2,6-naphthalate wafer containing ethylene 2,6-naphthalate units above 85 mol% and a silica compound in an amount of 50 to 1000 ppm and with an intrinsic viscosity of 0.70-1.20, to make a melt wound thread; (B) passage of the melt wound thread through a delayed cooling zone and a cooling zone to solidify the thread; (C) retraction of the wire at a rate such that the undrawn wire has a birefringence of 0.001-0.1; and (D) subjecting the non-wire drawing to a multiphase wire drawing in a total wire drawing ratio of at least 1.5 and at a wire drawing temperature of 50-250 ° C; and wherein the polyethylene naphthalate fiber has some properties of (1) an intrinsic viscosity of 0.60-1.10, (2) a toughness of 8.0-11 g / d, (3) an elongation of 6.0-15%, (4) a birefringence of at least 0.35, (5) a density of 1,355-1,368, (6) a melting point of 267-280 ° C, and (7) a contraction of 1- 5%. |