Study On The Development Of Low Torque Composite Yarns And Its Knitting Fabrics

The prevalence of multi-functional and top-quality knitted fabrics puts forward higherrequirements for its structures and properties. Spirality, the common distortion in the singleweft–knitting fabric such as plain stitch, influences not only the fabric appearance, but alsocauses cutting waste of the fabric. Many factors cause the spirality, including yarn properties,knitting and finishing processes. Among all these factors, the yarn residual torque causedduring the spinning is the fundamental one. In order to reduce yarn residual torque thusfundamentally control the spirality in single weft knitted fabrics, a new low torque Sirofilcomposite yarn with special structure was developed in this study, and the optimal spinningparameters were found. The force situation during the twisting triangle and the residual torqueequation of the low torque composite yarn were theoretically analyzed, and then themechanism of the residual torque decrease and other performance optimization werediscussed. Finally, the low torque composite yarns were used to produce low spirality singleweft knitted fabrics, then the fabric properties were examined and compared withcorresponding contrasted fabric woven with conventional ring spun yarns.The effect of the yarn linear density, yarn twist, inner yarn pre-tension and the spacingbetween the fiber fringing and the spun yarn on the composite yarns performance werediscussed. Under this test conditions, the optimal spinning parameters were determinedthrough orthogonal experiment and analysis: yarn density is18.3Tex, yarn twist is100/10cm,pre-tension of inner yarn is20cN, and the spacing is12mm.The structure of the low torque composite yarn was investigated. The mechanism of theresidual torque reduction may be interpreted as a certain proportion of residual torquecounteraction of inner yarn and composite yarn, since the inner yarn has a rotational tendencywhose direction is opposite to the composite yarn twist direction. The mechanism of otheryarn performances optimization are all associated with this special yarn structure.The results of the measurement of single weft knitted fabrics produced by using the lowtorque composite yarns and the conventional ring spun yarns show that the fabric spirality andtorsion degree can be dramatically reduced by the low torque composite yarns. Compared totheir control fabrics, the low spirality fabrics have better properties in tension strength,bursting strength, pilling resistance, wicking and etc, improving the inner and appearancequality of fabrics.