Color change after styling: In production, it is often encountered that polyester or polyester-containing fabrics have normal color and light after being dyed out of the vat, but then the color and light do not match after finishing in the next process, resulting in discoloration or local spots or strips. Color stains, decreased fastness, and other phenomena. In mild cases, such problems can be repaired through re-repair, but in severe cases, it is difficult to meet the requirements even after re-repair. This will have a certain impact on the normal production, delivery time, quality, and efficiency of the factory. and losses. The following is a brief explanation of its causes and preventive measures for the reference of peers.
Cause analysis
Thermal migration of polyester after dyeing with disperse dyes The phenomenon is the key to the above problems. Thermal migration is a common property of disperse dyes.
It refers to the fact that part of the dye migrates from the inside of the fiber to the surface of the fiber through the fiber capillary due to the action of dry heat or hot and humid air during high-temperature setting, resulting in the accumulation of dye on the surface of the fiber. And redistribution, the presence of additives and surfactants including residues on the cloth will aggravate its occurrence.
Since this thermal migration is mainly related to the structure of the dye itself, and disperse dyes with different structures have different thermal migration properties and are also very different from each other, so During post-finishing and high-temperature styling, especially when using silicone oil and antistatic, it contains a certain amount of surfactants. When these additives are unevenly adsorbed on the cloth surface, including uneven PH on the cloth surface, the above-mentioned problems will occur. The so-called color flowers, discoloration, and fastness decrease are a series of problems such as friction, washing, staining, etc. This phenomenon often manifests itself as one or several coexistences, which brings insurmountable hidden dangers and hazards to the dyeing quality.
Preventive measures
1. First, choose a product with low thermal migration and similar disperse dyes. Because these dyes have larger molecular weight structures and greater affinity with polyester fibers, they are difficult to migrate from the inside of the fiber to the surface.
2. When selecting color matching dyes, try to use the same type or high-temperature dyes, because different types of dyes have different thermal migration ratios, sublimation fastnesses, and high-temperature dyes. The sublimation fastness of the type is higher. Although the thermal migration fastness of the dye is not consistent with the sublimation fastness, the high-temperature dye has less sublimation of the dye under higher temperature setting, and the corresponding color light stability is also better.
3. The finishing process adopts a gentler process. The darker the color, the more the dye will migrate. The higher the temperature, the greater the impact on migration. In order to ensure the setting effect In this case, depending on the variety, a temperature of 150°C or lower can be used to avoid or reduce dye migration.
4. When choosing a finishing softener, try to use emulsifier-free hydrophilic silicone oil or self-emulsifying block silicone oil, and this type of silicone oil has good stability and color. It has low discoloration and yellowing, and has a better preventive effect on dye migration.
5. Strengthen the reduction cleaning after dyeing, especially for dark colors. The floating color must be fully cleaned to ensure its own fastness. At the same time, try to use acidic cleaning. If using alkali, When using the protective powder process, it must be neutralized, because some dyes are more sensitive to PH, and some will turn blue to purple after high-temperature treatment when PH>6, and some of this color change is irreversible or even irreversible. build.
Summary
In short, through the above measures and reasonable preparation, As for the processing and dyeing process, I believe that a series of quality problems such as color flowers, color change and decrease in fastness after finishing and shaping can be controlled within the scope of our requirements. </p
