The boiling, bleaching and dyeing processing of knitted fabrics are generally carried out in overflow tanks. During the entire processing process, the fabrics remain in a rope-like state. The fibers are constantly bent and deformed in the dyeing machine. The original hydrogen bonds are constantly destroyed, and new hydrogen bonds are formed. Bonds are constantly formed, and sometimes the newly formed hydrogen bonds cannot be fully restored, so chicken paw prints and dead creases are formed on the surface of the fabric.
In a single-sided fabric structure, the tension of the two yarn threads is asymmetrical, and it is difficult for the fabric to recover after being wrinkled in one direction for a long time. Therefore, plain weave and sweatshirts are used in various structures. , single pique, etc. are more likely to have fine wrinkles. The generation of fine wrinkles is also closely related to the yarn count and twist. The smaller the yarn count, the higher the twist, and the greater the possibility of reversal and untwisting of the yarn. This is reflected in the problem of fine wrinkles on the cloth surface.
The general dyeing and finishing process is:
Preparing cloth → sewing → dropping into vat and boiling and bleaching → dyeing → soaping → Fix color→soften→out of the vat→dehydration→dry the cloth with a shock wave machine or air dryer, and fine wrinkles are mainly formed in the dye vat, dehydrator, and fabric stacker…
Specific responses based on forming conditions
Pre-shaping
Improving fiber proximity through pre-shaping degree and orientation. When the fabric is heat-set, the fiber microstructure and morphology change. When the fabric is set, the fabric is fully stretched and set under high temperature. The fiber shape is fixed, which reduces the chance of changes in the dye vat, which is beneficial to Reduce creases.
Eliminate internal stress before dropping the cylinder
After loosening the cloth, fully relax it in the stacking car. Gray fabrics are generally stored in warehouses, and the relative humidity in the warehouse is low. If the cloths are stacked together for a long time in a very dry state, it is easy to produce indentations. After loosening the cloths, they should be placed in a place with high humidity in the workshop to fully regain moisture. The fiber swells to a certain extent when it regains moisture, and the internal stress is partially eliminated;
It is eliminated through the J-shaped groove. After the cloth is loosened, it is allowed to pass freely through the J-shaped groove and is squeezed by the pressure roller. Or roller drafting, the original hydrogen bonds are changed, which is beneficial to eliminating internal stress;
Through open-width stretching and superheated water to reduce fabric surface creases, knitted gray fabrics generally They are all cylindrical, and the cloth surface can be fully stretched through the cloth guide ring. At the same time, steam or superheated water can be sprayed to reduce creases. When superheating water, a certain amount of penetrant and smoothing agent can be added to fully moisten the cloth.
Bleaching and dyeing
Pay attention to the dye vat capacity and arrangement When dyeing, the dyeing process should generally be reduced by 10 to 15% according to the regulations of the dye vat, and must not be overloaded. When the amount of cloth is too large, the fabric will be seriously stressed in the cloth storage tank and cannot be stretched at the nozzle, and it is easy to form indentations;
Pay attention to the heating and cooling rate. When the heating or cooling rate is too fast, the temperature of the cloth body is likely to be uneven. When it is concentrated on one point of the fiber, the fiber will have different degrees of coldness and heat, and the shrinkage will be uneven, especially When the temperature is lowered, it is easy to be suddenly cooled locally, and the shape of the plastic fibers is solidified, forming wrinkles that are difficult to eliminate. Therefore, after a high-temperature process, the temperature is generally lowered to 70°C for drainage at a rate of 1 to 1.5/min, or cold water overflows directly after the high-temperature process, and the temperature is lowered before complete drainage.
Add lubricant to the dye bath to reduce the friction between fabrics and between fabrics and machinery, thereby reducing the chance of wrinkles. However, the choice of smoothing agent must take into account stability, and Processing process compatibility and other issues to avoid other problems caused by improper lubricant selection.
Choose more advanced machinery, increase the width of the cloth storage trough, and reduce the height of the lifting drum, which will help reduce the pressure on the cloth body. When using an air cylinder, the fabric will be at the nozzle After being fully blown open by high-pressure gas, the fibers get a “rest” from the tense state, which is conducive to the elimination of internal stress.
Drying method
When the fabric is dehydrated and dried, the fabric is dried in a high centrifugal force dehydrator Medium dehydration, if the time is too long, it is easy to produce wrinkles that are difficult to eliminate. Many dyeing factories are gradually adopting the method of water-drying cloth with open width, which not only improves the efficiency of drying cloth, but also helps solve the wrinkle problem. After padding, the cylindrical fabric can be widened through the guide ring and then dried using a shock wave machine. The open-width fabric can be widened and dried using a needle chain.
How to stack cloth
When stacking cloth on the cloth truck, the weight should not be too large and the time should not be too long. , especially when storing wet cloth, generally the amount of cloth per vehicle should not exceed 300Kg, and storage out of the cylinder should not exceed 6 hours.
The problem is the result of the entire process. It cannot be solved by adding an additive. It is related to the fiber, the fabric structure, the processing technology, and the processing. It is related to the equipment. After creases appear, generally minor creases can be solved by widening and shaping with a setting machine. Stubborn ones can be returned to the tank for washing water, and the temperature can be gradually raised to 85°C and then repaired in a process test where the temperature is gradually cooled to 50°C. Or it can be reshaped by adding steam shrinkage in an industrial polishing dryer. The dyeing factory can carry out repairs according to their own equipment and crease conditions. </p
