1) Scratches and fluffing of fabrics
In the airflow dyeing process, the fabric runs relatively fast. When it enters the nozzle and cloth guide tube, although it comes into contact with the dye liquor, it is not completely surrounded by the dye liquor like overflow dyeing. Therefore, a large friction force is generated between the fabric surface and the pipe wall, which may scratch the fabric surface in severe cases.
The fluffing or pilling of fabrics is mostly caused by external mechanical effects (stretching, friction), in addition to the high fiber strength and flexural resistance of fabrics and the large exposed yarn surface area (such as knitted fabrics). Therefore, the current solution is to improve the manufacturing accuracy of the inner surface of the equipment, and take measures such as appropriately reducing the fabric running speed and adding smoothing agents to eliminate or improve it.
2) Creases in the fabric
The airflow dyeing machine usually has a faster fabric speed, and its purpose is to increase the exchange frequency between the fabric and the dye liquor to ensure level dyeing; at the same time, it shortens the relatively static stagnation time of the fabric in the fabric storage and avoids creases in the fabric. Some light, thin, high-count and high-density filament fabrics are prone to scratches when the cloth speed is too fast; and creases will occur when the cloth speed is slow. In this case, it is necessary to find a suitable cloth speed.
The reason for the creases (longitudinal) that may appear in some knitted fabrics is that the knitted fabrics form large internal stresses during the weaving process. If the external warp tension is too large, warp creases will easily occur, and the warp creases will occur during the first time. It is formed during water processing (such as pre-treatment). In the subsequent dyeing process, the amount of dye adsorbed on the creases is different, forming marks of different shades. To avoid or reduce this phenomenon, during the pre-processing process, the air volume must be matched with the linear speed of the fabric lifting roller, so that the fabric has an expansion process after leaving the fabric guide tube, constantly changing the position of the bundle, so that the folding point can be quickly Expand. As long as the fabric does not form permanent creases after undergoing this process once, it will not form creases again during subsequent processing.
3) The color fastness of the fabric is reduced
When dyed with reactive dyes, the color fastness indicators of fabrics after air-flow dyeing are higher than those of ordinary overflow dyeing, which has also been confirmed by most good dyeing factories. However, some dyeing factories, especially those that have not really mastered airflow dyeing machines, have experienced a decrease in dye fastness. In fact, this is completely caused by not designing the dyeing process according to the characteristics of the airflow dyeing machine, but simply applying the process of the ordinary overflow dyeing machine. Analyzing the reason, the main reason is that the dyeing process takes too long, and the level dyeing time is mistakenly thought to be insufficient. As a result, the dye that has formed a chemical bond with the fiber is broken again, and is not effectively and fully removed during washing. Therefore, it is very important to develop a process suitable for air-flow dyeing, especially the time control. It must be considered that the same dye and the fabric to be dyed are dyed with the same color. The time for air-flow dyeing is shorter than that of ordinary overflow dyeing, because the fabric and the fabric are dyed with the same color. The frequency of dye liquor exchange is high and the time required to complete the same number of exchanges is short.
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