Analysis of Common Problems in Dyeing Polyester and Nylon Woven Socks

Dyeing is a key link in the production process of polyester and nylon woven socks, and its quality directly affects the appearance and market competitiveness of the product. Due to the differences in the chemical structure and physical properties of polyester and nylon fibers, the dyeing of polyester and nylon woven socks faces many challenges. This article will explore the common problems in the dyeing of polyester and nylon woven socks and provide corresponding solutions.

1. Principles and characteristics of dyeing polyester and nylon woven socks
Polyester and nylon are both hydrophobic fibers, but their molecular structures and properties are different. Polyester has a regular macromolecular structure, high crystallinity, high strength and wear resistance; nylon macromolecules contain polar groups such as amino and carboxyl groups, and have good elasticity and hygroscopicity. When dyeing, polyester mainly uses disperse dyes, while nylon often uses acid dyes or neutral dyes.

2. Common Problems in Dyeing Polyester and Nylon Woven Socks
(I) Color Difference Problem
Color difference between the two components of polyester and nylon: Due to the different chemical structures of polyester and nylon, the dyeing rate and affinity of disperse dyes on the two fibers are different, resulting in color difference between the two components of polyester and nylon. For example, during the dyeing process, polyester fibers usually have a higher affinity for disperse dyes than nylon fibers, which makes the polyester part darker and the nylon part lighter, resulting in uneven color.
Front-to-back color difference: In batch production, due to fluctuations in the temperature, time, dye concentration and other factors of the dyeing equipment, it is easy to cause front-to-back color differences between different batches of polyester-nylon interwoven socks. If the temperature control of the dyeing vat is inaccurate or the amount of dye added is inaccurate, the color of the dyed socks may be different from the standard sample.
(II) Color fastness problem
Poor washing color fastness: Polyester-nylon interwoven socks are prone to fading after washing. This is mainly due to the fact that the binding force of disperse dyes on polyester and nylon fibers is not strong enough, and the soap washing after dyeing is not sufficient. When the socks are subjected to friction and water impact during the washing process, the dye molecules are easy to fall off the fiber surface, making the color of the socks lighter.
Low sunlight color fastness: Under the action of light, the color of polyester-nylon interwoven socks will gradually fade. This is because disperse dyes will undergo photochemical reactions under ultraviolet light, causing changes in the molecular structure of the dye, thereby changing the color. Especially for some light-colored socks, the problem of sun color fastness is more obvious.
(III) Uneven dyeing problem
Uneven dyeing caused by fiber structure differences: The cross-sectional morphology and surface structure of polyester and nylon fibers are different, which affects the adsorption and diffusion of dyes on the fibers. The surface of polyester fiber is relatively smooth, while the surface of nylon fiber is relatively rough, which makes the distribution of dyes on the two fibers uneven, resulting in uneven dyeing.
Uneven dyeing caused by insufficient pretreatment: If the pretreatment of polyester-nylon interwoven socks before dyeing is insufficient, such as inadequate refining, the oil and impurities on the fiber surface are not completely removed, which will affect the adsorption and diffusion of the dye, resulting in uneven dyeing. For example, the oil on the fiber surface will hinder the contact between the dye molecules and the fiber, causing color spots or blocks to appear on the dyed socks.
(IV) Color fastness problem
Poor friction fastness: During the use of polyester-nylon interwoven socks, the surface color is easily worn due to friction. This is mainly due to the fact that the dye does not adhere strongly enough to the fiber surface and the fiber has poor wear resistance. When the socks rub against other objects, the dye molecules are easily shed from the fiber surface, making the color of the socks dim.
Low sweat fastness: When the human body sweats, polyester-nylon interwoven socks are prone to low sweat fastness. This is because the acid and alkali substances in the sweat will affect the binding force between the dye and the fiber, causing the dye to fall off the fiber. At the same time, impurities such as salt in the sweat will also have a certain effect on the dye, causing the color to change.

3. Solutions to the dyeing problem of polyester-nylon interwoven socks

(I) Solution to the color difference problem
Reasonable selection of dyes: Select disperse dyes with similar affinity for polyester and nylon to reduce the color difference between the two components. At the same time, the dye ratio can be adjusted according to different color requirements to make the color of polyester and nylon more coordinated.
Strict control of dyeing process: During the dyeing process, the process parameters such as dyeing temperature, time, and dye concentration must be strictly controlled to ensure that the dyeing conditions of each batch are consistent. The use of automated dyeing equipment can improve the accuracy and stability of dyeing, thereby reducing the color difference before and after.
(II) Solution to the problem of color fastness
Auxiliary treatment to improve dyeing fastness: The use of appropriate auxiliaries, such as fixing agents, anti-migration agents, etc., can improve the binding force of dyes on fibers, thereby improving color fastness. For example, fixing agents can form chemical bonds with dye molecules to make dyes more firmly attached to fibers, thereby improving water washing fastness and sunlight fastness.
Optimize post-dyeing treatment process: Strengthen the soaping and washing processes after dyeing to ensure that the dye residue is fully washed. At the same time, appropriate post-treatment processes, such as drying and stretching, can be used to improve the color fastness and feel of socks.
(III) Solution to the problem of uneven dyeing
Improve the pre-treatment process: Strengthen the pre-treatment of polyester-nylon interwoven socks to ensure that oil stains, impurities, etc. on the fiber surface are completely removed. Select appropriate scouring agents and desizing agents to improve the effect of pre-treatment. For example, a scouring agent containing surfactants and alkali agents can be used to fully scour the fibers to make the fiber surface clean and smooth, which is conducive to the adsorption and diffusion of dyes.
Optimize dyeing process and equipment: The use of appropriate dyeing process and equipment, such as high temperature and high pressure dyeing machines, can improve the uniformity of dyeing. At the same time, during the dyeing process, the dye solution should be fully circulated and stirred so that the dye molecules can be evenly in contact with the fibers, thereby reducing the uneven dyeing phenomenon.
(IV) Solution to the problem of dyeing fastness
Improve the wear resistance of fibers: Through appropriate post-finishing processes, such as softening finishing and anti-pilling finishing, the wear resistance and anti-pilling properties of polyester-nylon interwoven socks can be improved, thereby indirectly improving the dyeing fastness. For example, softening finishing can make the fiber surface smoother and reduce the shedding of dyes during friction.
Select suitable dyes and auxiliaries: Select dyes with better fastness properties and use suitable auxiliaries, such as anti-staining agents, antioxidants, etc., to improve the dyeing fastness. For example, anti-staining agents can prevent dyes from staining other parts during friction, thereby improving friction fastness.

4. Summary
There are many common problems in the dyeing process of polyester-brocade interwoven socks, such as color difference, color fastness, uneven dyeing, etc. These problems not only affect the appearance quality of the product, but also may affect its market competitiveness. These problems can be effectively solved and the dyeing quality of polyester-brocade interwoven socks can be improved by rationally selecting dyes, optimizing dyeing processes, improving pre-treatment and post-treatment processes, etc.