| 摘要 |
PURPOSE:To provide the titled fiber produced by high-speed spinning at a winding speed higher than a specific level and having an unevenness of birefringence along the fiber cross-section direction falling within a specific range, uniform cross-section structure, decreased orientation unevenness in the cross-section of fiber and remarkably improved passability in post-treatment step and dyeing speck. CONSTITUTION:The objective fiber having an unevenness of birefringence along the fiber cross-section direction falling within the range specified by formula [DELTAn is average birefringence of polyethylene terephthalate fiber; delta(DELTAn) is difference between the maximum value and the minimum value of birefringence distribution along the cross-section of polyethylene terephthalate fiber] and uniform cross-section structure can be produced by using a polyethylene terephthalate of [eta]=0.75 as a high molecular weight component and a polyethylene terephthalate of [eta]=0.65 as low molecular weight polymer as a core and the low molecular weight polymer as a sheath using a nozzle having a ore/sheath structure at 290 deg.C and winding the spun fiber at a winding speed of as high as >=3,000m/min.
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