A fiber made from a polyester containing 2-20 mole % of a comonomer component represented by general formula (1); yarns wherein the above fibers are used, i.e., blended yarns composed of filaments with different shrinkage percentages, yarns of core-sheath type, and blended staple yarns; and composite fibers containing the polyester as a component. The invention fiber has a low birefringence and excellent dyeability and bathochromic effect. Further it has, depending on the stretching conditions, not only a high shrinkage percentage but also a high shrinkage force and remarkably excellent lightfastness, thus being useful as a substitute for conventional high-shrinkage fibers. In formula (1) R₁ to R₁₀ represent each a group selected from an ester-forming functional group, hydrogen and alkyl, provided one or two of them is (are) ester-forming functional group(s); and x is 0 or 1 and y is an integer satisfying the condition of 1 ≦ x+y ≦ 3.
一种由含有 2-20 摩尔%由通式(1)表示的共聚单体成分的聚酯制成的纤维;使用上述纤维的纱线,即由不同收缩率的长丝组成的混纺纱线、包芯纱线和混纺短纤纱线;以及含有聚酯成分的复合纤维。本发明的纤维具有低双折射、出色的染色性和变色效果。此外,根据拉伸条件的不同,本发明的纤维不仅收缩率高,而且收缩力大,耐光性极佳,可替代传统的高收缩纤维。在式 (1) 中,R₁ 至 R₁₀ 各代表一个选自
酯类形成官能团、氢和烷基的基团,条件是其中一个或两个是
酯类形成官能团;x 是 0 或 1,y 是满足 1 ≦ x+y ≦ 3 条件的整数。