Research On Pre-wetting Sizing And Its Influence On The Quality Of Cotton Yarns

Pre-wetting sizing is a new sizing process. In this process, warp should be immersed into water and be cleaned firstly. So warp is wet before it enters into size box. Pre-wetting can be achieved by a pre-wetting size box or spraying. Pre-wetting size box is used usually at home and abroad. Its advantages, improving sizing quality and saving size have been accepted by enterprises and scholars.This paper is mainly about the study on sizing effect and qualities of yarns after pre-wetting sizing through a series of experiments, including the following aspects:(1) Design four different sizing processes to size the cotton yarns and observe the soaking and coating of the sizing agent under a scanning electron microscope. Interface mechanism is studied firstly according to knowledge of interface physical chemistry to research the distribution of sizing agent after pre-wetting sizing in light of wetting property and attachment between size and yarn. (2) In light of quality indicators of sizing yarns, determine the sizing percentage, hairiness and mechanical indicators of yarns which are sized in different conditions. Through the comparison and the analysis to the experimental results, it points out that the influence of pre-wetting sizing on the quality of cotton yarns. (3) It puts forward the concept of "pre-wetting and pre-drying", which is a new thinking about sizing process.In the pre-wetting sizing process, the cotton wax and other impurity are removed from the surface of warp after the infiltration and washing in the size box with a high temperature above 85℃. As a result of it, the angleθreduces which is useful to the spreading and wetting of size. After the pressure of roller and pre-wetting in the size box, the space between fibers which is occupied by air originally has been replaced by hot water. Because there is a concentration difference between size solution and hot water, they will exchange. Thus in the radial area of yarn, the dead-end pores where the water is difficult to soak in the traditional process also exist solution. The size solution tends to be distributed more evenly in the yarns, the adhesion between fibers increases and the quality of yarns enhances.The main indicators of quality of yarns are size percentage, hairiness and mechanical property (especially is the Young's modulus). Pre-wetting process can reduce the size percentage of yarn, if the solution is added wetting agent, we should choose a proper concentration to balance the decrease of size percentage and amelioration of weaving performance. The concentration of solution is higher; the amount of hairiness is less. Pre-wetting process with a wetting agent demands a proper concentration as a high concentration of agent isn't good to reduce the amount of hairiness. The broken strength of yarn increases after pre-wetting sizing, different concentration of solution and wetting agent has different effect on Young's modulus. Since the time constraint, it doesn't research on the proper concentration.