POLYVINYL ALCOHOL-BASED FIBER AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a polyvinyl alcohol-based fiber with high mechanical strength and moist heat resistance by spinning and wet drawing a polyvinyl alcohol-based polymer followed by inparting a specific cyclic acetalized product to the drawn fiber and then performing a dry heat drawing and acidic water bath treatment. SOLUTION: This polyvinyl alcohol-based fiber is obtained by the following process: a polyvinyl alcohol-based fiber produced by spinning of a polyvinyl alcohol-based polymer solution followed by wet drawing of the spun fiber is imparted with a cyclic acetalized product of an aliphatic aldehyde shown by formula I (R1 and R2 are each a 1-5C alkyl; (n) is an integer of 1-5) or formula II (R3 is a 1-5C alkyl; (n) is an integer of 1-4) (e.g. 2,4-dimethoxytetrahydrofuran) and then subjected to dry heat drawing followed by treatment under a condition satisfying the relationship: 137/C<0.05> -47<=T<=137/C<0.05> -25 (C is the sulfuric acid concentration of the aqueous solution of sulfuric acid: g/L; T is treatment temperature: deg.C). This polyvinyl alcohol-based fiber thus obtained has the following characteristics: the internal crosslink index CI and tensile strength DT satisfy the relationship: CI>=86.5-2×10<6>×(DT)<5.8> , CI>=75, and DT15 g/d.