PURPOSE: To obtain the subject filament having excellent strength and abrasion resistance and low variation ratio of knotting strength by heat-treating a polyvinylidene fluoride single filament having a specific double refractive index at a temperature lower than melting point of the polymer and heat-treating the single filament at high temperature in a high-temperature inert gas for a short time under tension.
CONSTITUTION: A polyvinylidene fluoride monofilament having ≥25×10-3 double refractive index is heat-treated in a liquid or inert gas heated to 50°C to a temperature lower than melting point of the polymer for 1-30sec in relaxing ratio of 3-15% and then heat-treated at high temperature for short time under tension in an inert gas heated to 530-1000°C or heated and drawn in ≤1.2 times draw ratio at high temperature for short time to provide the objective polyvinylidene fluoride monofilament having high tensile strength and knotting strength and low variation ratio of knotting strength and high abrasion resistance and remarkably improved in impact knotting strength and useful for aquatic raw material of fishing line, fishing net, lever net, etc., raw material for reinforcement of rubber belt and transportation of sling, rope, etc., engineering raw material of fence, prevention of dropping stone, etc.
NAKADA HIDEO
SATO TAKUJI
