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.
Residual 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.
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.
Thermal migration of disperse dyes can cause a series of effects, such as color change, staining other fabrics during ironing, reduced rubbing fastness, reduced fastness to washing and perspiration, dry cleaning and light fastness. degree decrease, 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.
The method to prevent thermal migration of disperse dyes is:
(1) Any additives remaining on the fiber before dyeing should be removed regardless of whether they can cause thermal migration of the dye. net.
(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 resin finishing, 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) is used as a solvent. Put the fabric into the fabric for 3 minutes. Any dye that migrates to the fiber surface should be able to peel off in the dimethylformamide, while the dye in the fiber will not peel off. The migration amount can also be determined by colorimetric method, still using dimethylformamide as the solvent, and processing for 5-10mi in the boiling state. Eventually, all the dye on the fiber will peel off.
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