POLYVINYLALKOHOLFASER UND VERFAHREN ZUR HERSTELLUNG DERSELBEN.

摘要

A high tenacity, high initial modulus polyvinyl alcohol fiber showing a high level of crystalline heat of fusion, characterized in that the fiber is made of polyvinyl alcohol having a degree of polymerization of not less than 1,500, has a tenacity of not less than 17 g/d and an initial modulus of elasticity of not less than 400 g/d and shows a crystalline heat of fusion of not less than 29 cal/g, and a method of producing said polyvinyl alcohol fiber comprising: (1) dissolving polyvinyl alcohol with a degree of polymerization of not less than 1,500 in a solvent capable of giving a 5 wt% polyvinyl alcohol solution and the solvent is further characterized in that the nuclear magnetic resonance spectrum measured at 50 DEG C after storage of the solution at 50 DEG C for 96 hours following preparation thereof is substantially identical with that measured at 50 DEG C immediately after preparation thereof, with peaks for the three kinds of hydroxyl groups of polyvinyl alcohol being clearly distinguishable in each nuclear magnetic resonance spectrum, (ii) forming unstretched filaments by spinning the spinning solution under conditions which satisfy the requirement Ds