It is well known that the spandex fiber can be dyed with disperse dyes and acid dyes, but the fastness of these two dyes is poor. Most experiments have proved that reactive dyes for nylon and disperse cationic dyes basically do not leave color on the spandex. Does this indicate that the two dyes are not suitable for spandex dyeing? In fact, it is not so. With the catalysis of the appropriate auxiliaries, reactive dyes for nylon can be used for the dyeing of the spandex, and its fastness and depth are better. The following is a detailed analysis.
1. There are few pure spandex fabrics in the market, so the dyeing of spandex is relatively unfamiliar to us. Pure spandex fabrics can be used in conjunction with low elastic fabrics or inelastic fabrics, which can increase the elasticity and resilience of fabrics. And when the elastic fabric is stretched or pressed, if the color of spandex fiber is not consistent with the filament, there will be the problem of the color leakage of the spandex, which requires the dyeing of spandex.
2. For light color dyeing of the spandex, acidic dye or disperse dye can be used in acidic bath conditions. Under the condition of using the same dye dosage, disperse dyes have better fastness than acidic dyes on the spandex, but different disperse dyes have different fastness on the spandex. In general, if the dye dosage is less than 0.5%, disperse dyes can be adopted.
3. Spandex fiber is high elastic fiber. Considering that dyeing spandex for a long time under a high temperature will lead to elastic failure, it is generally dyed below 100℃. What's more,spandex is not resistant to alkali, and disperse dyes and acid dyes are suitable for dyeing in acidic conditions. In general, the dyeing of spandex is conducted in acidic conditions with a pH of about 5.
4. A variety of dyes, with suitable auxiliaries as mediums, can be used to dye the spandex fiber. This kind of auxiliaries in the market is called spandex coloring agent or spandex colorant, which is mainly used for the dying of reactive dyes for nylon and acid dyes on spandex, which generally boast amphoteric ion properties. The action principle is rough as follows: Under acidic conditions, the amide bond and other groups in the spandex ionize, with a positive charge, which may have a reaction with the spandex colorant. Then fixing agent is fixed in the spandex because the spandex colorant contains amino positive ions, the dye and spandex colorant can also be combined.
5. General rules of the fastness after the dyeing of spandex: Wash > sweat stain (acid) > soaking, and the fastness of web rubbing is far better than that of dry rubbing.