| 摘要 |
<p>A polyethylene naphthalate fiber comprising ethylene naphthalate units as main repeating units. The polyethylene naphthalate fiber is characterized in that the fiber, when analyzed by X-ray wide-angle diffractometry, has a crystal volume of 100-200 nm3 and a crystallinity of 30-60%. Preferably, the fiber in X-ray wide-angle diffractometry has a maximum peak diffraction angle of 23.0-25.0° and the exothermic-peak energy as measured during cooling at a cooling rate of 10 °C/min in a nitrogen gas stream (?Hcd) is 15-50 J/g. Also provided is a process for producing the fiber, characterized in that a polymer in a molten state which contains a specific phosphorus compound is used and the spinning speed is 4,000-8,000 m/min. The process is further characterized in that the molten polymer ejected from the spinneret is passed, immediately after the ejection, through a heating spinning cylinder having a temperature higher by more than 50°C than the molten-polymer temperature and is stretched.</p> |
