01 Disperse dye dyeing migration
Polyester dyed with disperse dyes can produce a thermal migration phenomenon during high-temperature treatment (such as setting), which is post-dye migration. The phenomenon of thermal migration is caused by residual additives in the outer layer of the fiber. Under high temperature or long-term storage conditions, additives can attract and dissolve dyes and move dyes to the fiber surface. The remaining additives mainly come from the following two aspects:
1. Antistatic agents added during spinning and weaving.
2. Antistatic agents, penetrants, anti-pollution agents and softeners added during dyeing and post-processing.
The auxiliaries added during spinning, weaving and dyeing should be basically washed during the production process. The remaining additives on the fiber during post-processing are the main ones.
02 Problems caused by thermal migration of disperse dyes
Thermal migration of disperse dyes can cause a series of effects, such as changes in color and light, and Contamination of other fabrics, decreased rubbing fastness, decreased fastness to washing and perspiration, decreased fastness to dry cleaning and light fastness, etc. Thermal migration is related to the processing temperature and time. Thermal migration phenomenon has no absolute relationship with the sublimation fastness of the dye.
Thermal migration phenomenon is a redistribution phenomenon of disperse dyes in two-phase solution (fiber and additives). Therefore, all additives that can dissolve disperse dyes, regardless of their ionicity and chemical structure, can produce thermal migration. If there is no second phase solution, there will be no thermal migration phenomenon; if the second phase solution is weakly soluble in the dye , the thermal migration phenomenon will also weaken accordingly.
It has been found from production practice that non-ionic surfactants, which are widely used, are the cause of thermal migration of dyes. Generally, the instability of disperse dyes in nonionic surfactants is closely related to temperature, but the different chemical structures of various dyes are also related to stability. For example, Disperse Blue 58 can be completely decomposed in a non-ionic surfactant at 130°C in 5 minutes. Under the same conditions, Disperse Orange 20 only decomposes 10% in 30 minutes.
03 Methods to prevent thermal migration
1. All additives remaining on the fiber before dyeing, regardless of whether they can cause thermal migration of the dye, should be removed Divide.
2. The auxiliaries used in the dyeing process should be removed after dyeing.
3. The additives used in post-dyeing treatment, such as softeners, penetrants, antistatic agents, antifouling agents, etc., must be carefully selected. Only those products that will not cause thermal migration can be used.
4. When finishing resin, not only the sublimation property of disperse dyes must be considered, but also the commonly used penetrant JFC must be washed away after finishing.
Check whether there is thermal migration in the dyed fabric. Dimethylformamide (DMF) can be used as a solvent and the fabric is put into the water for 3 minutes. Any dye that migrates to the fiber surface should be able to peel off in DMF. in, while the dye in the fiber does not peel off. The migration amount can also be measured using a colorimetric method, still using dimethylformamide as the solvent, and processing in the boiling state for 5-10 minutes. Eventually, all the dye on the fiber will peel off.
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