Technological reasons and treatment methods of slub silk
The production of slub yarn is basically due to craftsmanship, and less mechanically.
(1) Reasons for raw materials
①In slub silk, the slub knots are obviously harder. Observed with a 40x microscope, the large black-gray impurities can be seen more clearly. This is due to impurities in the raw material, especially elongated impurities that pass through the filter; if under a 40x microscope, the visible white impurities may be uneven dispersion of the masterbatch or unground particles in the masterbatch. It is recommended to increase the number of filters.
②The nodules of slub silk are not hard, and the nodules are soft or have transparent bright spots. Under a 40x microscope, bright spots of unmelted polymer can be clearly seen. This may be because the raw materials contain high melting point polymers or materials. Melt plasticization is not good. If the raw material contains a high melting point polymer, it is recommended to increase the extrusion temperature appropriately, but the effect cannot be seen, and the raw material can only be replaced. If the material is not melted and plasticized, it is recommended to adjust the temperature of the extruder, and the raw material can be stirred and pre-plasticized to reduce the extrusion amount, control the flow rate, etc.
③In slub silk, the nodules are not hard, and the nodules are soft or have transparent bright spots. Methods such as adjusting the temperature of the extruder were ineffective and the filaments broke frequently. The raw material model may be incorrect or the raw material melt index is unstable. Replacing raw materials is recommended.
(2) Reasons for process control
①The slub joint has no defects. The flat wire before the joint is thicker and the bamboo joint is longer than the flat wire after the joint. This is due to longitudinally non-uniform film thickness. The flat yarn after the splice is thin and stretched in advance to achieve the draft ratio. The thicker part of the back is still unstretched, forming the slub yarn. It is recommended to check the cause of the film thickness.
②The slub wire joint has no defects, the node deviates from the necking point, and the drafting point moves into the arc plate, but it is not drawn. This could be due to low draft temperatures or poor heat transfer from the arc plate. It is recommended to adjust the arc plate or oven temperature; if the stretching speed is too fast, the heat of the flat ribbon is too much, and the arc plate or oven cannot provide enough heat, it is recommended to reduce the stretching speed.
③ There are more slub yarns, which may be caused by insufficient draft ratio and insufficient stretching. It is recommended to increase the draft ratio.
④The temperature of the cooling water is high, and the recovered flat yarn is prone to produce slub yarn.
⑤ The temperature of the drying board is too high, and most of the flat yarns entering the drying board reach the stretching temperature and begin to stretch; the temperature of the hot air in the oven is uneven, and the heating is uneven, and a single flat yarn with a low heating temperature appears as a slub yarn.
⑥The raw materials are not dried, and thick filaments are prone to appear on the drawings of recycled materials.
There is too much water in the film, the water entering the flat belt of the drying plate is not equal, and the flat wire is heated unevenly, forming a slub line. It is recommended to control the amount of water carried by the membrane.
⑧ The drawing speed is too fast or too slow.
(3) Mechanical reasons
①The slub joint has no defects. Reasons other than the above may be fluctuations in the drawing tension, the flat yarn slips on the drafting roller, the instantaneous tension is insufficient and has not been drawn. Look for causes of tension fluctuations, such as draft rolls.
②The curved plate is uneven and has poor contact. Polished curved plate.
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