THICK DIAMETER POLYVINYL ALCOHOL-BASED FIBER AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a polyvinyl alcohol(PVA)-based fiber having a thick diameter and a high cross-sectional circularity and useful for a fabric and a reinforcing material for civil engineering and construction and the like by carrying out dry spinning of a hydrous chip containing a vinyl alcohol-based polymer from a spinning hole into a gas and producing the fiber under specific conditions. SOLUTION: A hydrous chip containing a vinyl alcohol-based polymer is subjected to dry spinning from a spinning hole into a gas and the resultant filament is continuously dried by using a roller-type dryer under the temperature conditions of <=180 deg.C until the moisture content of the filament attains 0.5-4 wt.%/PVA. The dried filament flattened by pressing thereof against a roller in the drying step is then subjected to dry hot drawing at 215-250 deg.C at >=5 times to suddenly foam the moisture contained in the filament under tension. Thereby, the fiber cross section is rounded to produce a PVA-based fiber having >=300 d monofilament fineness, >=80% cross-sectional circularity and >=2.8 g/d strength.