| 摘要 |
PURPOSE:To obtain the titled fiber having specific birefringence, strength at break and a elongation at break, high strength, and excellent adhesivity as a reinforcing material for rubber, by subjecting an undrawn polyamide yarn to multi-stage elongation under specific condition and then to relaxation treatment. CONSTITUTION:A polyamide having a relative viscosity of 2.3-3.5 is melt-spun, and taken up under a condition to obtain an undrawn yarn having a birefringence of <=13X10<-2>. A predraft of <20% is applied between the first roller and the second roller for the feeding of the undrawn yarn, and the yarn is subjected to the first-stage drawing under the stream of super-heated steam of >=200 deg.C at a draw ratio corresponding to >=50% of the total draw ratio. Thereafter, the second-stage drawing is carried out with a non-contact heater having a temperature gradient increasing toward the outlet-side, between the first-stage drawing roller of >=100 deg.C and the second-stage roller of >=150 deg.C. The drawn yarn is subjected to the relaxation treatment at a relaxation ratio of 3-15% to obtain the objective fiber satisfying the characteristics of the formulas II-IV, and having a birefringence satisfying the formula I. |
