Wrinkles, that is, creases or chicken paw prints, have always been a difficult problem to solve in the dyeing and finishing of chemical fiber or cotton knitted fabrics, especially elastic knitted fabrics containing spandex. In view of the high elasticity and ductility of spandex itself, it is difficult to solve It is more likely to produce or form new wrinkles during processing. In severe cases, it is difficult to meet the requirements even after repairs, which will have a certain impact and loss on the product quality and efficiency of the factory.
Causes of wrinkles
The main reason why ammonia-containing elastic knitted fabrics form wrinkles is because when the fabric in the cylinder is folded and squeezed when the temperature rises and cools too quickly, the fibers shrink unevenly in a short time, and the coils will shift and deform to form wrinkles; At the same time, during the processing and post-styling of the fabric after it comes out of the vat, if the temperature of the fabric itself is too high or the cooling is not enough, and the spandex shrinks before it rebounds and is stacked for a long time, it will also easily lead to wrinkles.
Precaution
1. Strengthen pre-treatment equipment and operations: Whether ammonia-containing elastic fabrics are refined in open width or rope form, the synchronization between the equipment guide rollers must be strengthened or improved to prevent the fabric surface from being pulled and squeezed, and finally washed with room temperature water to prevent Wrinkles will occur if the temperature is overheated and the fabric is piled up too much, too high, or for too long.
2. Strictly control the pre-setting process: Pre-setting can prevent curling, wrinkling and stabilize the door width. Without affecting the elasticity and feel of the spandex, a slightly higher temperature can be used for shaping. For example, polyester and spandex can be controlled at 190-195 ℃, nylon ammonia 185-190 ℃, cotton ammonia 180-185 ℃, the vehicle speed is generally 15-20m. At the same time, keep the fabric surface flat to prevent shrinkage and wrinkles.
3. Adjust the nozzle pressure and lifting roller speed during dyeing: coordinate the two according to the weight of the fabric to prevent tangling, pressing the cylinder, and blocking the cloth. If necessary, increase the bath ratio, reduce the amount of baths, and add baths. Add anti-wrinkle agent or increase cloth speed, etc.
4. Control the heating and cooling speed: Strictly operate according to the computer program settings, strengthen process discipline, control the temperature not to exceed 1-1.5°C/min, and prevent excessive speed from causing fiber aggregation and shrinkage to cause a large number of wrinkles.
5. Doing a good job in post-shaping can effectively reduce the dropping temperature, and appropriately raising the setting temperature can help eliminate wrinkles and slight wrinkles in the previous process. Generally, depending on the type, the controlled temperature of chemical fibers can be 10-20°C lower than the predetermined temperature, and that of cotton can be lowered by 20-30°C. At the same time, it is best to blow cold air and cool down the cooling roller at the cloth outlet to ensure that the cloth surface is below 50°C, otherwise the temperature will be lower than the predetermined temperature. Heat pressing can create new wrinkles.
6. In addition, if the unwinding loose cloth in the front line is left for too long, the spandex shrinks and wrinkles are formed on the edge of the cloth. It must be booked in time to avoid it, including dehydration after dyeing. More than 2-3 hours.
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