Abstract:

Objective Aiming at uneven of segment colored yarns made by three-roller and four-roller methods, coaxial double rear rollers were adopted to achieve the same linear density cotton/wool siro segment colored yarn by the method of two sets of roving at the same spindle position and equal coupled feeding. Two rovings are fed on the same position, and the drafting control condition of two rovings is consistent. The roller speed can be coupled to achieve equal fiber feeding. However, the spinning process, yarn structure and properties of cotton/wool siro segment colored yarn produced by coaxial roller spinning technology are rarely studied.

Method Cotton/wool siro segment colored yarn with constant linear density was spun on HFX-A4J ring spinning frame. Two rovings were fed into the coaxial double rear roller equally at the same position. The lengths of spinning segmentation time were 1, 2, 4, 8 s, and the mass ratio cotton to wool during spinning were 87.5/12.5, 80/20, 75/25, 62.5/37.5 and 55/45. The influences of the proportion of mass ratio cotton to wool and the segmentation time on the breaking strength, evenness and hairiness of the colored yarn were investigated. The longitudinal and sectional yarn morphologies were observed with the KH1300 three-dimensional video microscope made by Questar Ltd.

Results As is shown in the longitudinal and cross-sectional images of the yarn, the segment color effect of the yarn is more obvious with the increase of the difference in the mass ratio cotton to wool and the segmentation time. Owing to the different mass ratio cotton to wool in the adjacent two segments, the segment color effect appears in the longitudinal direction of the yarn. With the longitudinal observation results of the yarn, the longer the segmentation time is, the longer is the color segment length. Cross-sectional observations show that the cotton and wool fibers are compressed and wrapped in the yarn to form a structure similar to Yin and Yang fish of the Tai Chi pattern. When the mass ratio cotton to wool is constant, the breaking strength of the yarn decreases as the split time increases, and when the segmentation time is fixed, the yarn breaking strength decreases with the increase of the segment mass ratio cotton to wool difference. When the segment time is shorter than 2 s, the yarn breaking strength decreases slightly with the increase of segment mass ratio cotton to wool difference. When the segmentation time is more than 4 s, the breaking strength of yarn decreases greatly with the increase of segment mass ratio cotton to wool difference. The evenness of cotton/wool segment colored yarn suggested that when the mass ratio cotton to wool is constant, the evenness increases with the increase of segmentation time. When the segment ation time is fixed, the unevenness of the yarn increases with the increase of segment mass ratio cotton to wool difference. With the increase of segment time, the ratio of roller speed change transition time to segmentation time decreases, the difference between real mass ratio cotton to wool and the designed value decreases, and the CV value of yarn increases with the increase of segment mass ratio cotton to wool difference.

Conclusion As the diameter of wool fiber is thicker than cotton fiber, the total number of fibers in the cross section of yarn segment decreases with the increase of the mass ratio of wool, which reduces the breaking strength of the yarn segment and ultimately the breaking strength of the whole yarn. When the segmentation time is within 2 s and the difference of mass ratio cotton to wool is not more than 75/25, the cotton/wool segment colored yarn with weak segment color effect is produced, and the breaking strength and evenness of the yarn meet with the requirements of wearing performance. With such a yarn, woven fabric can be designed for colored patterns. This spinning method enriches the product types of existing fancy yarns. Meanwhile, under the condition of simple modification of the spinning frame, the strand-style wool-like segment color yarn is produced.

Key words: cotton/wool segment colored yarn, coaxial double roller, siro spun yarn, yarn structure, yarn property