What are the disadvantages of the reactive dyeing method?

In jet stream machine dyeing, the operation mode of the fabric is that the dyed fabric enters the nozzle through the guide roller, and the hydraulic pressure generated by the circulating pump is used to send the fabric into the cloth conveying duct, and then into the cylinder from the end of the machine, and slowly move toward the dyeing liquid. Moving forward, after reaching the machine head, it enters the nozzle through the guide roller, thus forming an endless loop.

After the fabric enters the cylinder from the tail, there are five characteristics in the process of soaking the dye solution:

①The fabric is basically in a rope state;

②About 2/3 to 3/4 of the fabric is immersed in the liquid, and 1/3 to 1/4 of the fabric is floating on the liquid surface (especially the light fabric with small weight or the fabric with poor hydrophilicity);

③ The stacking state of the fabric in the cylinder is basically unchanged, and it is relatively static;

④The fabric and the fabric are squeezed together and stacked tightly (especially when the amount of the fabric is large);

⑤The fabric stays statically in the cylinder for a long time (domestic locomotives are slower. When each tube is equipped with a cylinder of 700-800m, it usually takes 3 to 4 minutes to circulate once, especially when dyeing some delicate fabrics. , Such as nylon/cotton twill with nylon on the front, nylon/cotton straight tribute, etc.). Sometimes in order to avoid scratches, the vehicle speed is often slowed down deliberately, and the stacking time is longer.

Production practice shows that the above characteristics are one of the root causes of uneven color in jet overflow dyeing. The reason is obvious, because when the fabric is immersed in the dyeing liquid in the cylinder, the fabric is in a rope shape, squeezed and closely contacted, and stacked relatively static for a long time. In addition, part of the fabric is exposed above the liquid surface. The following problems will inevitably arise: the surface of the outer fabric has a fast renewal speed of the dye liquor, while the surface of the inner fabric has a much slower renewal speed of the dye liquor.

Due to the objective difference in the exchange and renewal speed of the dye liquor on the inner and outer surface of the fabric, the concentration of the dye liquor inside the fabric is always lower than that of the main circulating dye liquor. Therefore, when the dye uptake rate is faster or the feeding operation is improper, it is easy to cause The dye distribution is uneven and colored.