Oriented polyamide fiber and process for producing same

摘要

There are disclosed oriented polyamide fiber which comprises at least 20% by weight of a crystalline polyamide or a copolymerized polyamide each produced by polymerizing a monomer containing m-xylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component each in an amount of at least 70 mol% (A) and which has a Young's modulus of at least 400 kgf/mm<2>, a loop strength of at least 4.5 gf/D, a knot tensile strength of at least 3.5 gf/D and a roundness of from 97 to 100%; and a process for producing oriented polyamide fiber which comprises the steps of melting a polyamide resin comprising at least 20% by weight of the above crystalline polyamide or copolymerized polyamide (A); spinning the molten resin through a spinneret; pulling the spun product into a coolant bath placed beneath the face of the spinneret to produce non-oriented yarn; and thereafter orienting the non-oriented yarn to a draw ratio of from 2.5 to 8.0 at a temperature not lower than the Tg of the polyamide and not higher than the melting point thereof, wherein the draft ratio is from 1.0 to 3.0, and the temperature of the coolant bath (T) satisfies the relational expression: Tg - 30