PURPOSE: To easily obtain the subject fiber having excellent heat-resistance and mechanical strength and useful as a raw material for composite material, a material for woven or knit fabric, etc., by spinning a specific polyether copolymer and drawing the spun fiber under a specific condition.
CONSTITUTION: The objective fiber is produced by spinning a polyether copolymer containing the recurring units of formula I and formula II at a molar ratio of the unit I of 0.15-0.35 and having a melt viscosity (zero-shear viscosity) of 8,000-50,000 poise at 400°C and drawing the obtained undrawn fiber at a temperature higher than the glass transition temperature of said polyether copolymer by 10-30% at a draw ratio of ≥1.5. The above copolymer can be produced e.g. by reacting a dihalogeno-benzonitrile with an alkali metal compound of 4,4'-biphenol in the presence of a neutral polar solvent and copolymerizing the reaction product with a 4,4'-dihalogenobenzophenone.
MURAKAMI SHIGERU
MATSUO SHIGERU
