What are the reasons and solutions for windprinting of polyester fabrics?

Posted by Admin ---14 Feb 2022

Wind print generally refers to a coloring defect produced in the drying and storage process of printed and dyed fabrics. The cause of windmarks on fabrics is mainly related to dyes. Usually, a few vat dyes, Naphtol dyes, some vinyl sulfone reactive dyes and most direct dyes can produce windmarks due to their poor fastness to sunlight and oxidation. Because some reactive dyes are highly sensitive to alkali, if the cloth surface is not cleaned with alkali after coloring, windmarks will easily occur when the pH value is large T8 (such as reactive turquoise KN-G, reactive bright orange G, etc.) . Polyester fabrics are also prone to windmarks during the dyeing and finishing process. However, the root causes and solutions for windmarks are rarely reported.

Polyester fabric is not easy to produce windmark during continuous production (long car production line), but it is easy to produce windmark in intermittent production (high temperature and high pressure overflow coloring). The wind print of polyester fabric is mostly produced in the link after the fabric is dehydrated and opened and before it is set, and the location appears in the reciprocating fold and print when the stacker is stored. In severe cases, dozens of lines will appear in the weft direction, and the spacing is exactly the spacing of the reciprocating folding of the natural cotton cloth. Compared with the normal colored blank, the windmark will appear red, white or dark gray stripes in the weft direction of almost the entire width of the door. What is difficult to understand is that it cannot be seen before it is set, and it will be generated after it is set.

For example, the non-staple polyester woven fabric or polyester knitted fabric, its technological process is: coloring → post-processing → dehydration → opening → setting → fabric inspection. After the opening of such fabrics, they are placed to be shaped. The reciprocating folds are exposed to air, and the flow of air causes the moisture in these parts to evaporate and dry first. Due to the capillary effect, free water from other parts will rush to the reciprocating fold. However, a small amount of antistatic agents, lubricants added during spinning and weaving, leveling agents and cleaning agents added during coloring and post-treatment will still remain in the cloth and free water carried by the cloth, and most of these auxiliaries For non-ionic additives. Similar to the principle of dye migration, when free water flows to the reciprocating folds that are first evaporated and air-dried, the residual additives dissolved in free water also flock to the reciprocating folds. With the further volatilization of water, the concentration of additives in the reciprocating fold is bound to be much higher than that in other parts.