| 摘要 |
PROBLEM TO BE SOLVED: To provide a latent crimping thick-and-thin polyester yarn developing soft touch and bulky feeling as well as stretch performance by the development of crimp. SOLUTION: The latent crimping thick-and-thin polyester yarn has a birefringence of 40×10-3 to 70×10-3 at the thick part and 80×10-3 to 130×10-3 at the thin part. The birefringence in the cross-section of the filament of the thin part is deviated from the center of filament and the difference of the birefringence values between the outer layer and the inner layer is 20×10-3 to 50×10-3. The yarn can be produced e.g. by using an apparatus shown in the figure, applying an aqueous liquid to the yarn at a point upstream of the thinning end point of the yarn by 5-20 cm to effect anisotropic cooling and setting the spinning speed to 2,000-4,000 m/min, the drawing temperature to the glass transition point or below and the draw ratio to 1.1-2.3.
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