Overview of polyester coloring

dyeing

In high temperature and high pressure dyeing, the dyeing process of polyester fiber with disperse dyes can be divided into the following stages:

(1) In the dye solution, the disperse dye gradually approaches the fiber interface with the flow of the dye solution. At this stage, the properties and states of the disperse dye are basically independent. The dissolved dye molecules and suspended dye particles all flow with the dye solution, and the transfer rate is determined by the flow rate of the solution.

(2) As there is a dynamic boundary layer on the fiber surface that is not easy to flow, when the disperse dyes enter the dynamic boundary layer and are close to the fiber interface, they approach the fiber mainly by their own diffusion. In this stage, the transfer velocity is not only related to the flow velocity of the solution, but also related to the diffusion velocity of the disperse dye. Therefore, the dissolved dye molecules are much faster than the suspension and aggregate diffusion, and the solubility and dispersion state of the disperse dye have a great impact on the transfer velocity of this stage.

(3) After the disperse dyes are close to the fiber interface and the molecular force between them is large enough, the disperse dyes are quickly absorbed by the fiber surface. The transfer rate at this stage is mainly determined by the structure and properties of the fiber and dye molecules, as well as the properties of the interfacial solution. Among them, the solubility and dispersion state of dyes have a great influence, the ultra-high solubility of dyes and the greater the effect of dye molecules and fibers, the faster the adsorption rate.

(4) After the disperse dye is adsorbed to the fiber surface, a concentration difference or internal and external dye chemical potential difference will be generated in the fiber, and the dye will diffuse into the fiber interior, where the diffusion rate is mainly determined by the fiber chemistry and microstructure, and also related to the dye molecular structure and concentration. Fiber amorphous zone content is higher, the pore is large or free volume content is more, dye solubility is high, diffusion speed is fast, therefore, the dye diffusion speed of this stage is directly related to the degree of swelling or plasticization of fiber, disperse dye in the fiber concentration. High degree of swelling or plasticization, fiber