Analysis of common problems in textile sizing

1 Causes of yarn hairiness and improvement measures The hairiness of yarn can be divided into three categories: original yarn hairiness (primary hairiness), sizing hairiness (secondary hairiness), and regenerated hairiness (hairiness produced by weaving). 1.1 Original yarn hairiness The cause of formation of original yarn hairiness has been deeply studied by scholars. In the spinning process, the fibers in the twisting triangle are subjected to the dual action of tension and twisting force, resulting in centripetal force. The fiber repeatedly transfers inside and outside, so that one or both ends of the fiber are exposed outside the yarn body, and finally hairiness is formed. 1.1.1 The law of change The hairiness of the original yarn starts from spinning and increases from the winding. Both long hairiness and short hairiness will increase exponentially after warp winding, as shown in Table 1. 1.1.2 Distribution law For bobbins, the hairiness is the most for small yarns, the least for middle yarns, and slightly more for large yarns; 1 mm Short hairiness of ～2 mm is the main component of yarn hairiness, which is less harmful. Although the proportion of hairiness above 3 mm is not high, it is very harmful to weaving production. JC 14.8 tex ring spinning bobbin has 1 mm hairiness, 2 mm hairiness, 3 mm hairiness, 4 mm hairiness, 5 mm hairiness, 6 mm hairiness, 7 mm hairiness, and 8 mm hairiness. The results are 482.06 pieces/10 m, 81.53 pieces/10 m, 22.19 pieces/10 m, 9.53 pieces/10 m, 4.86 pieces/10 m, 2.39 pieces/10 m, 1.49 pieces/10 m, 0.49 pieces/10 m. It can be seen that as the length of hairiness increases, the hairiness of the bobbin yarn decreases sharply. 1.2 Sizing hairiness Sizing hairiness (secondary hairiness) refers to the harmful long hairiness that is produced during the sizing process and is sizing. These sizing harmful hairs have two characteristics. One is that as the amount of PVA and the sizing rate increase, the degree of harm to weaving also increases. The second is that the sizing rate of sizing hairiness is greater than that of yarn. Observing from the microscope, the sizing rate of hairiness is estimated to be 1 to 2 times the weight of the hairiness. Sometimes, the end of the hairiness will form a pellet-like slurry. That is to say, The starched hairiness is more harmful. 1.2.1 Reasons for the formation of improper selection of slurry, not following the principle of 'similar compatibility'. The size has poor adhesion to the yarn, and the size film is not wear-resistant and has poor integrity. In the slurry formulation, the compatibility is unreasonable, and the tear strength and toughness of the serosa film are too high (especially a large amount of PVA with complete alcoholysis is used). In this way, it is easy to cause the resistance of sizing to dry and skein, the interface between the sizing film and the yarn is broken, the sizing film is broken, and the sizing hairiness and falling objects are generated. The sizing rate is too high or too low. If the sizing rate is too high, it increases the resistance of dry splitting; if the sizing rate is too low, the sizing fluid cannot fit the hairiness. At the same time, attention should be paid to that the ratio of sizing liquid to yarn penetration and covering should be suitable for the sizing requirements of the variety. Excessive penetration and insufficient penetration will have a negative impact. The dryness of the sizing yarn is also the cause of the hairiness of the sizing yarn. The sizing regained dryness, the sizing film became brittle, the adhesion and softness would decrease, and the sizing was severely dropped during dry splitting, which increased the hairiness of the sizing. 1.2.2 Improvement measures The selection of slurry must first be based on the principle of 'similar compatibilityThe wrong size is selected, not to mention the reduction of hairiness, even the quality of the size is difficult to guarantee. Secondly, the adhesiveness of the size is very important. Without good adhesiveness, there will be no good abrasion resistance. Without good abrasion resistance, sizing hairiness and regenerated hairiness (generated by weaving friction) are inevitable. Attention should also be paid to the film-forming properties of the slurry. The non-film-forming slurry is not recommended as the main slurry. It is possible to use a small amount appropriately. When the slurry is compatible, it is necessary to consider that the tear strength of the slurry film should not be too high, otherwise the splitting resistance will be large, so it is necessary to carefully choose PVA with different polymerization degrees and alcoholysis degrees. Choosing the amount of PVA carefully is an important principle for making good use of PVA and reducing the hairiness of sizing. In the case of conditions, less use of PVA has a good effect on reducing hairiness. The size of the sizing rate should be determined according to the specific conditions of the enterprise through experiments, and the appropriate proportion of slurry penetration and covering should be considered. The proportion is not specified, only the range. Because the size of the sizing rate can only be compared with the same varieties of the company, this is the most realistic. The sizing regain will increase the dry hairiness, and the wet regain will decrease. Everyone has this experience. According to the environmental conditions of the company's weaving workshop and the seasonal climate, a slightly larger regain will help reduce hairiness and falling objects. 1.2.3 Other experience wet splitting to protect the serosa. This is an effective experience recognized by the sizing industry, even if it is pre-drying without stratification, wearing a wet slicing rod is effective in reducing the resistance of dry slicing. Layered pre-bake, the effect is remarkable. Layered pre-drying can reduce the coverage coefficient of the sizing during drying, can effectively ensure the integrity of the sizing film, and reduce the hairiness of the sizing. The surface of the drying cylinder is coated with a PTFE anti-sticking layer. Reduce the peeling force between the drying cylinder and the sizing, make the sizing film complete, and reduce the hairiness of the sizing. High-pressure sizing is used.