| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyethylene naphthalate fiber and to provide a method for producing the fiber and to provide a polyethylene naphthalate fiber cord for industrial materials by using the fiber. SOLUTION: In the polyethylene naphthalate fiber containing≥80% ethylene-2,6-naphthalate unit, the strength is≥6cN/dtex and elongation in the secondary yield point is≤8%. The method for producing the polyethylene naphthalate fiber includes pre-stretching of a fiber so as to satisfy conditions in which the fiber temperature is 80°C to 120°C and pre-stretch tension is 0.05-0.3 N/dtex between a take-up roller and a first drawing roller, carrying out first stretching of the fiber under conditions in which the fiber temperature is 130°C to 180°C and the stretching tension is not higher than pre-stretching tension, setting total drawing magnification including the subsequent drawing to≥5 times and finally carrying out tense heat treatment of the fiber at a stretch ratio of 0-2%. COPYRIGHT: (C)2008,JPO&INPIT
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