The characteristics of rotor (rotor spun) yarn and its main differences from ring spun yarn include seven aspects: strength, evenness, wear resistance, elasticity, etc., which are described as follows:
Strong
Due to the large number of bent, looped, folded, and wrapped fibers in rotor yarns, and the poor degree of fiber transfer between the inner and outer layers, when the yarn is subjected to external forces, the unevenness of fiber breakage is relatively severe, and due to the short contact length between the fiber and the fiber, the fiber is prone to slip when subjected to external forces, so the strength of rotor yarns is lower than that of ring spun yarns. When spinning cotton; The strength of rotor spun yarn is about 10-20% lower than that of ring spun yarn; When spinning chemical fibers, it is about 20-30% lower.
Evenness of stripe
Rotor spinning does not require roller drafting, and therefore does not generate mechanical and drafting waves that ring spun yarn has. However, if there are hard impurities embedded in the coagulation tank, periodic irregularities equal to the circumference of the spinning cup can also occur. In addition, if the carding roller winds around the flower, has poor fiber separation, or has irregular movement of fibers, it can also cause uneven evenness of coarse and fine knots. However, in general, the carding roller has a strong carding effect, has a good fiber separation, and has fewer defects such as fiber seed chips and cotton strands, which is conducive to evenness of evenness. In addition, there is a unifying effect in the condensation process of rotor spinning. Therefore, the evenness of rotor yarns is more uniform than that of ring spun yarns. The average Ubbelohde unevenness of medium to high quality rotor yarns is 11 to 12%, some of which are lower than 10%, while that of ring spun yarns is 12 to 13%.
In addition, when raw cotton passes through the front spinning machine, it has a strong function of opening and removing impurities, and there is a lot of impurities removed, especially through the spinner with a impurity removal device. At the same time, due to the separation of fibers and impurities in the spinning cup, a small portion of dust and neps are left in the spinning cup, so the rotor yarn is relatively clean and has fewer yarn defects. The number of yarn defects in rotor yarns is only 1/4 to 1/3 of that in ring spun yarns.
Abrasion resistance
The abrasion resistance of yarns is not only related to the uniformity of the yarn itself, but also closely related to the yarn structure. "Because ring spun yarn fibers exhibit regular spiral threads, when repeatedly rubbed, the spiral fibers gradually become axial fibers, causing the entire yarn to lose twist and disintegrate and quickly break.". The outer layer of the rotor yarn is wrapped with irregular winding fibers, so the rotor yarn is not easy to disintegrate, and thus has good wear resistance. Generally, the abrasion resistance of rotor yarns is 10-15% higher than that of ring spun yarns. As for the abrasion resistance of rotor spun yarn, due to its rough surface and good adhesion between yarns, rotor spun yarn has better abrasion resistance than ring spun yarn.
elastic
Spinning tension and twist are the main factors that affect yarn elasticity. Generally speaking, the spinning tension is high and the yarn elasticity is poor; High twist and good yarn elasticity. Due to high spinning tension, fibers tend to exceed the elastic deformation range, and it is difficult for fibers in the yarn to slide after spinning, resulting in poor elasticity. The yarn has a large twist and a large inclination angle of the fiber. When stretched, it exhibits spring-like elongation, so it has good elasticity. Rotor yarn belongs to low tension spinning and has more twist than ring spun yarn, so rotor yarn has better elasticity than ring spun yarn.
twist
Generally, the twist of rotor yarn is about 20% more than that of ring spun yarn, which will cause difficulties in some post processing. For example, the processing of certain pile fabrics is more difficult. At the same time, high twist makes the yarn feel hard, affecting the feel of the fabric. Therefore, it is necessary to study measures to reduce the twist of rotor yarn while ensuring a certain single yarn strength and yarn breakage.
Fluffiness
The bulkiness of the yarn is expressed by the specific volume (c ㎡/g). Due to the poor straightness and irregular arrangement of the fibers in the rotor yarn, the tension on the yarn during twisting is relatively small, and the outer layer is wrapped with winding fibers, so the structure of the rotor yarn is fluffy. Generally, the specific volume of rotor spun yarn is about 10-15% higher than that of ring spun yarn.
Dyeability and pulp absorption
Due to the fluffy structure of the rotor yarn, which has strong water absorption, the rotor yarn has good dyeing and sizing properties. The use of dyes can be reduced by 15-20%, and the size concentration can be reduced by 10-20%.
