Stained

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 dyeing solution in the dyeing solution. At this stage, the nature and state of the disperse dyes are basically irrelevant. The dissolved dye molecules and suspended dye particles are the same with the dyeing solution and the transfer speed Determined by the solution flow rate.China polyester FDY Yarns Suppliers

(2) Since there is a dynamic boundary layer that is not easy to flow on the fiber surface, when the disperse dye enters the dynamic boundary layer and approaches the fiber interface, it will approach the fiber mainly by its own diffusion. 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 dye. Therefore, the dissolved dye molecules diffuse much faster than the suspension and aggregates. The solubility and dispersion state of the disperse dye affect the transfer speed of this stage. Have a greater impact. High-strength polyester yarn

(3) When the disperse dye is close to the fiber interface and the molecular force between them is large enough, the disperse dye is quickly absorbed by 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 nature of the interface solution. Among them, the solubility and dispersion state of the dye have a greater impact. The higher the solubility of the dye and the greater the interaction between dye molecules and fibers, the faster the adsorption speed.

(4) After the disperse dye is adsorbed on the fiber surface, there will be a concentration difference or chemical position difference between the inner and outer dyes in the fiber, and the dye will diffuse into the fiber. The diffusion speed here is mainly determined by the fiber chemistry and microstructure, as well as the dye molecule. Structure and concentration are related. Fiber has a higher content of amorphous regions, large pores or more free volume, high dye solubility, and fast diffusion. Therefore, the dye diffusion rate at this stage is directly related to the degree of swelling or plasticization of the fiber and the concentration of disperse dye in the fiber . The degree of swelling or plasticization is high, and the concentration of disperse dye in the outer fiber layer is high, and the diffusion is fast.

In addition to the dyeing speed is determined by the structure of the dye and fiber, it is also related to 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 bind to dyes like cellulose or protein fibers. Polyester molecules are arranged relatively tightly, and there are only small voids in the fiber. When it is lower, the thermal motion of the molecule changes its position to a smaller extent. Under humid conditions, the polyester fiber will not increase the gap through violent swelling like cotton fiber, and it is difficult for 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 auxiliary. The functions of these dyeing auxiliaries in the dyeing process are multifaceted, mainly:

(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.

The general auxiliaries used in high-tamp and high-pressure dyeing of polyester fibers contain carriers that plasticize fibers, surfactants that solubilize disperse dyes or stabilize dye suspensions, etc. The dyeing auxiliaries play a very important role in dyeing polyester fibers.

Re-dyeing: Polyester fiber and filament fabrics have strong hydrophobicity. The usual dyes and dyeing methods can hardly be dyed. They can only be dyed with disperse dyes, but the whole process of such dyeing can only be completed under high temperature and high pressure. .

Industrial application

Polyester is widely used in the manufacture of clothing and industrial products. Due to its long-term flame retardancy, flame-retardant polyester has a wide range of applications. In addition to its irreplaceable role in industrial textiles, architectural interior decoration, and vehicle interior decoration, it also plays a lot of roles in the field of protective clothing. According to the national standards for flame-retardant protective clothing, metallurgy, forestry, chemical, petroleum, and fire protection departments should use flame-retardant protective clothing. The number of people who should use flame-retardant protective clothing in China is more than one million, and the market potential of flame-retardant protective clothing is huge. In addition to pure flame-retardant polyester, it can produce flame-retardant, waterproof, oil-repellent, anti-static and other multi-functional products according to the special requirements of users. For example, waterproof and oil-repellent finishing of flame-retardant polyester fabric can improve the functionality of flame-retardant clothing; use flame-retardant polyester and conductive fiber to produce antistatic flame-retardant fabric; use flame-retardant fiber and high-performance fiber for blending and interweaving , Can produce high-performance flame-retardant fabrics; use flame-retardant fiber blended with cotton, viscose and other fibers to improve the comfort of protective clothing and reduce secondary burns.