What is the dyeing mechanism of polyester fiber?

Polyester fiber is a hydrophobic synthetic fiber. The molecular structure of polyester lacks active groups that can combine with dyes. Polyester molecules are arranged relatively tightly, and there are only small voids in the fiber. When the temperature is low, the molecules move thermally. The range of changing its position is small, and it is difficult for the dye molecules to penetrate into the fiber. Therefore, increasing the degree of plasticization of the fiber will help the dyeing process. In addition, the solubility of disperse dyes in water is very low, and the dyes in the dyeing solution must be dispersed in the dyeing bath in suspension by a large amount of dispersant. When dyeing polyester fiber, in order to achieve better dyeing effect, it is usually necessary to add a certain amount of dyeing auxiliaries.

The functions of these dyeing auxiliaries in the dyeing process are multifaceted, mainly including:

       1. Appropriately increase the solubility of disperse dyes;

       2. Promote the adsorption of disperse dyes on the fiber surface;

       3. Plasticize the fiber or increase the degree of swelling to speed up the diffusion of disperse dyes in the fiber;

       4. Improve the dispersion stability of the dye.