Abstract:

Objective In order to give full play to the performance advantages of composite staple yarn, a new method of spinning staple sheath-core yarn based on ring spinning machine was developed. Meanwhile, tensile properties and abrasion resistance are important evaluation indicators of textiles, which are directly related to production efficiency and product quality. Therefore, the tensile properties and abrasion resistance of pure cotton ring-spun yarns and cotton-polyester staple sheath-core yarns and their corresponding fabrics were also compared.

Method The conventional front roller was replaced with the coaxial front roller of different diameters. The two fiber bundles were simultaneously fed into the back roller. After drafting, they were output with different speeds at the front roller nip. Under the action of spinning tension, the slow fiber bundle was output perpendicular to the front roller nip, while the fast fiber bundle was output from the front roller nip at a certain inclination angle and converged with the slow fiber bundle at the twisting point. As the twist was transferred to the spinning triangle, the slow fiber bundle was twisted around its axis, while the fast fiber bundle was spirally wrapped around the outside of the slow fiber bundle, thus forming staple sheath-core yarn.

Results The breaking strength and breaking elongation of the cotton-polyester staple sheath-core yarn are better than those of the ring-spun cotton yarn. And as the core proportion increases, the breaking strength and breaking elongation of the staple sheath-core yarn increase. This is because the tensile properties of polyester fiber are better than those of cotton fiber. As the core proportion increases, the polyester fiber content increases, so the tensile properties of the sheath-core yarn are improved. The tensile properties of staple fiber sheath-core yarn and ring-spun cotton yarn improve as the twist increases. Meanwhile, the abrasion resistance of ring-spun cotton yarn is better than that of cotton-polyester sheath-core yarn. The reason is that internal and external transfer exist between the fibers of ring-spun cotton yarn, and the binding force between fibers is strong and difficult to be extracted. While, the sheath-core yarn has an obvious layered structure, and the cohesive force between the core layer and the sheath layer is insufficient, making the fibers easier to peel off. Therefore, the abrasion resistance of cotton-polyester staple sheath-core yarn is worse than that of ring-spun cotton yarn. Similar to the law of yarn tensile properties, the tensile properties of knitted fabrics woven from polyester-cotton staple sheath-core yarns are superior to than those woven from ring-spun cotton yarns. This is because the fiber strength determines the tensile properties of the yarn, which in turn affects the tensile properties of the fabric. Therefore, an increase in the polyester fiber content is beneficial to improving the tensile breaking strength and breaking elongation of the knitted fabric. The strength loss proportion of the knitted fabric woven form ring-spun cotton yarn is much greater than that woven from sheath-core yarn fabric. This is because the strength of the sheath-core yarn is mainly provided by the core layer. During friction, the core layer is covered by the sheath layer and suffers little friction, resulting in less strength loss of the sheath-core yarn. Therefore, the strength loss proportion of the knitted fabric woven from staple sheath-core yarn is much smaller than that woven from ring-spun cotton yarn.

Conclusion A new method of spinning staple sheath-core yarn based on ring spinning machine was developed. the two fiber bundles were output at different speeds at the nip of the front roller by modifying the front roller on the ring spinning machine. Under the action of spinning tension and twisting, the slow fiber bundle was covered by the fast fiber bundle, forming a sheath-core structure. This method has the advantages of high spinning efficiency and good yarn spun properties. In addition, the tensile properties and abrasion resistance of ring-spun cotton yarn and cotton-polyester sheath-core staple fiber yarn were compared. The results show that the tensile properties of cotton-polyester staple sheath-core yarn were better than those of ring-spun cotton yarn; However, the abrasion resistance of cotton-polyester staple sheath-core yarn is worse than that of ring-spun cotton yarn; and the tensile properties of knitted fabric woven from cotton-polyester staple sheath-core yarn were better than that woven from ring-spun cotton yarn.

Key words: new spinning technology, cotton/polyester staple sheath-core yarn, coaxial front roller of different diameters, sheath-core proportion, tensile property, abrasion resistance property, weft-knitted fabric