Patent ID: 6955854
Filing Date: 2005-10-18
Classification: B60C,D01F,D02G,D10B,Y10T

Abstract:
1. A polyethylene naphthalate fiber produced by a method comprising the steps of: (A) melt-spinning a solid phase-polymerized polyethylene-2,6-naphthalate chip containing ethylene-2,6-naphthalate units at more than 85 mole % and a silica compound and having an intrinsic viscosity of 0.70-1.20, to produce a melt-spun yarn; (B) passing the melt-spun yarn through a retarded cooling zone and a cooling zone to solidify the yarn; (C) withdrawing the yarn at such a speed that the undrawn yarn has a birefringence of 0.001-0.1; and (D) subjecting the undrawn yarn to multi-stage drawing at a total draw ratio of at least 1.5 and a drawing temperature of 50-250 C; and wherein the polyethylene naphthalate fiber having some properties of (1) an intrinsic viscosity of 0.60-1.10. (2) a tenacity 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 of267-280 C, and (7) a shrinkage of 1-5%.