Why Are Polyester Yarn Fabrics Prone To Color Stains?

　　After the polyester yarn knitted fabric is dyed under high temperature and high pressure, due to the high oil content of the gray fabric during weaving, the oligomers produced by the agglomeration of fibers and dye molecules will cause color stains and seriously affect the quality of the product. To control the occurrence of this problem, the analysis, discussion, and research of color stains were carried out, the specific method of controlling the problem was found, and preventive measures were proposed, which improved the product quality and increased the company's economic benefits.

　　Polyester yarn knitted fabric:

　　Polyester yarn is a hydrophobic fiber, the fiber lacks groups that can combine with dyes, and cannot be dyed with water-soluble dyes. It can only be dyed with non-ionic dispersed dyes with small molecular weight, no strong ionic water-soluble groups, and low solubility. . Polyester yarn has a compact structure and is dyed under normal pressure. It is difficult for the dye to diffuse into the fiber and dye the fiber thoroughly. Therefore, high-temperature and high-pressure dyeing are used.

　　Dyeing with dispersed dyes

　　1. Disperse dyes are carried out in a humid heat state with high temperature and pressure.

　　2. The dye is dispersed in an aqueous solution with multiple single-crystal molecules in a granular state through a dispersant. Its dyeing rate is very slow within 100 ° C. Even if it is dyed in a boiling dye bath, the dyeing rate and percentage of dyeing are not high. , so the pressure must be below 2atm (2.02×105Pa), and the temperature of the dye bath can be increased to 120-130°C. Due to the increase in temperature, the chain segments of fiber molecules move violently, and more and larger instantaneous pores are generated. At this time The diffusion of dye molecules is also accelerated, which increases the diffusion rate of dyes to the inside of the fiber and accelerates the dyeing rate until the dyes are exhausted and the dyeing is completed.

　　3. Due to the low solubility of dispersed dyes in water, the dyes in the dyeing liquid need to be dispersed in the dye bath in suspension through a large amount of dispersant when dyeing polyester yarn fibers. To achieve a better dyeing effect.

　　4. To achieve a better dyeing effect, it is usually necessary to add a certain amount of dyeing auxiliaries. The main functions of these dyeing auxiliaries in the dyeing process are:

　　Increase the solubility of disperse dyes, promote the adsorption of disperse dyes on the fiber surface, plasticize the fibers or increase the degree of swelling, accelerate the diffusion speed of disperse dyes in fibers, and improve the dispersion stability of dyes.

　　5. Generally, the auxiliaries used in high-temperature and high-pressure dyeing of polyester yarn fibers include carriers for fiber plasticization, surfactants for solubilizing disperse dyes or stabilizing dye suspensions, etc. Dyeing auxiliaries are very important for polyester yarn fiber dyeing. effect.

　　Polyester DTY yarn is prone to color stains (color spots) type

　　1 color stain

　　Most of the things that are the same as the dyed color, darker, and have the same prints have front and back sides, and sometimes there are dirty things on the stains, which can be picked off. Such color points and stains account for more than 60% of the total. Most of them appear irregularly, ranging in size from mung beans to soybeans, but in severe cases, they are as large as fingernails.

　　2 black dots

　　It is mainly concentrated in brown, including light brown, light beige, coffee, and dark brown. It is a small black color point the size of a sesame seed as if a black oil-based pen has been tapped on the cloth.

　　3 color points of the dyed color

　　Its color print is darker than the previous case, and it is not big, and sometimes it can be picked off. Generally, there are more at both ends of a vat of cloth and less in the middle.

　　These three types can be found when the dye vat is out of the cloth. When it came out, the color was slightly repaired by a repair agent, and the color was seriously changed to black.

　　4 scattered color points

　　There is also a kind of black golden spot, which is not there when the cloth is out of the cloth, but after the cloth is dried by a dryer, there will be a golden spot. This kind of yellow spot can be removed with an alkali + degreasing agent. Especially when it is changed to black, it is more likely to appear, and it is scattered on the cloth surface.