Stripe coloring technology

Stripe coloring technology

dyeing

During high temperature and high pressure dyeing, the dyeing process of disperse dyes on polyester fibers can be divided into the following stages:

(1) The disperse dyes gradually approach the fiber interface with the flow of the dye solution in the dye solution. At this stage, the properties and states of the disperse dyes are basically irrelevant. The dissolved dye molecules and the suspended dye particles flow with the dye solution. Depends on the solution flow rate.

(2) Since there is a dynamic boundary layer that is not easy to flow on the surface of the fiber, when the disperse dye enters the dynamic boundary layer and approaches the fiber interface, it mainly relies on its own diffusion to approach the fiber. The transfer speed at this stage is not only related to the flow rate of the solution, but also to the diffusion speed of the disperse dyes. Therefore, the dissolved dye molecules diffuse much faster than the suspensions and aggregates. The solubility and dispersion state of the disperse dyes affect the transfer speed at this stage. have a greater impact. High strength polyester yarn

(3) When the disperse dyes are close to the fiber interface and the molecular force between them is large enough, the disperse dyes are quickly adsorbed on the fiber surface. The transfer speed at this stage is mainly determined by the structure and properties of the fibers and dye molecules, and is also related to the properties of the interfacial solution. Among them, the solubility and dispersion state of the dye have a great influence. The high solubility of the dye and the greater the interaction between the dye molecule and the fiber, the faster the adsorption speed.

(4) After the disperse dye is adsorbed to the fiber surface, a concentration difference or chemical potential difference between the inner and outer dyes will be generated in the fiber, and the dye will diffuse into the fiber. The diffusion speed here mainly depends on the fiber chemistry and microstructure, and also with the dye molecules. structure and concentration. The content of the amorphous region of the fiber is high, the pores or free volume content are large, the dye solubility is high, and the diffusion speed is fast. Therefore, the dye diffusion speed at this stage is directly related to the degree of fiber swelling or plasticization, and the concentration of disperse dyes in the fiber. . The degree of swelling or plasticization is high, the concentration of disperse dyes in the outer layer of the fiber is high, and the diffusion is fast.

The dyeing speed depends not only on the structure of the dye and the fiber, but also on the solubility of the dye in the solution and the degree of swelling or plasticization of the fiber during dyeing.

Polyester fiber is a hydrophobic synthetic fiber. The molecular structure of polyester lacks active groups that can combine with dyes like cellulose or protein fibers. Polyester molecules are arranged relatively closely, and there are only small voids in the fiber. When it is lower, the molecular thermal motion changes its position to a small extent. Under wet conditions, polyester fibers will not swell violently to increase the voids like cotton fibers, and it is difficult for dye molecules to penetrate into the fibers. . Therefore, increasing the degree of plasticization of the fiber will help the dyeing. In addition, the solubility of disperse dyes in water is very low, and the dyes in the dye liquor are dispersed in the dye bath in the form of suspension by a large amount of dispersants. 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 multi-faceted, 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 rate of disperse dyes in the fiber;

(4) Improve the dispersion stability of dyes.

The auxiliaries used in general high-pressure high-pressure dyeing of polyester fibers contain carriers for plasticizing fibers, surfactants for solubilizing disperse dyes or stabilizing dye suspensions, etc. Dyeing auxiliaries play a very important role in polyester fiber dyeing.

Counter-dyeing: Polyester fibers and filament fabrics have strong hydrophobicity, and the usual dyes and dyeing methods are almost impossible to dye, only disperse dyes can be used, but the whole process of such dyeing can be completed under high temperature and high pressure .