Surfactants play an important role in the successful completion of dyeing

2020-05-22 15:09:51

In acid bath dyeing, amino groups of silk can absorb acid, neutral, direct dyes and anionic surfactants with negative charges. At this time, anionic surfactants and dyes compete for dye bases according to their affinity. When anionic surfactants have a larger affinity, the rate of dye adsorbed by fibers slows down, which reduces the dye uptake rate of anionic dyes. As a retarder, it plays a role in retarding dye uptake, which is of great significance for neutral dyes with high dye uptake rate in the early stage. However, in the weak acid and neutral conditions, if the affinity of anionic surfactant to silk is too strong or the amount of anionic surfactant is too much, there will be too many dyes left in the dyeing bath, which is too uneconomical. Therefore, when the temperature is high, neutral salts (such as salt and sodium chloride) are often added to promote dyeing, and the dyeing will be even, and the dyes will be used as much as possible. In silk dyeing, the anionic surfactants, such as Archaean oil, pancreatin bleaching T, Sodium Alkylbenzene Sulfonate, sodium alkylsulfate, sodium fatty acid, naphthalene sulfonate formaldehyde condensate, all have strong retarding effect.

① With the participation of surfactants, the surface tension of dye solution is significantly reduced, and the wetted surface of fiber surface is greatly reduced, so that the fiber is wetted and permeated into the interior when the dye dissolves, the dyeing process is accelerated, and the dyeing time is shortened. In the dyeing process of silk fabrics, the addition of O, JFC, archaic oil, and pancreatin bleaching t all play this role.

② When dyeing insoluble or insoluble disperse dyes, azo dyes and so on, the addition of surfactants makes the dyes fully disperse and solubilize, which plays a very important role in the successful completion of dyeing. When neutral dyes and acid dyes are used to dye silk fabrics, the dyes are not easy to disperse sufficiently to form agglomerates at low temperature, which depends on surfactants with strong dispersing power.

③ The low cloud point of nonionic surfactant is harmful to dyeing, but the addition of anionic surfactant will make the cloud point rise above 100 ℃.

(4) foaming in dyeing bath is a negative function of surfactant in dyeing.