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Why does the application of disperse or direct blended dyes sometimes produce color spots, but sometimes no?

This problem is universal in the actual production of high temperature and high pressure jet overflow dyeing machine. It is mainly caused by improper control of dyeing process and improper use of additives. To prevent this problem, we generally need to pay attention to the following three points:

1.When dyeing, high-temperature leveling agent (for polyester) and detergent with low foam and high cloud point (for cotton or viscose) should be added at the same time, which can effectively prevent the possible color flower formed by the above two dyes.
2.The direct blend dye itself contains a certain amount of electrolyte, however, Electrolytes (NaCl or Na2SO4) still need to be added to promote dyeing, especially direct dyes with salt effect. However, the excessive amount of electrolytes in the dyeing bath will affect the stability of disperse dyes and form color flowers. Therefore, it can be added after the dyeing is basically completed and the temperature drops to about 85 ~ 90% (when there is no pressure in the machine), and then heat preservation dyeing for about 20min. This not only does not affect the stability of disperse dyes, but also ensures that the direct blended dyes have sufficient lifting force, and can reduce the residual amount of dyes in the dyeing residue, which is conducive to wastewater treatment.
3.In the control of the overall dyeing process curve, it should also be noted that after the temperature rises to 130% (0.18 MPa) for thermal insulation dyeing for 30 ~ 45 minutes and the temperature drops to 85 ℃, it is necessary to continue thermal insulation dyeing for about 20 minutes to make the direct blended dyes achieve transparent dyeing, so as to significantly improve the reproducibility of dyeing.

In addition, in order to completely prevent this situation, the influence of fabric pretreatment effect and dyeing water cannot be ruled out.

Post time: Mar-15-2022