How to improve the dyeing quality of overflow dyeing machine?

1. The influence of the capacity of overflow dyeing machine
Overflow dyeing machine has a very large nominal capacity, but this nominal capacity is not suitable for any fabric. Therefore, in production, it is necessary to determine the actual capacity of the overflow dyeing machine according to the thickness, width and other conditions of the fabric. For fabrics of the same width, the thinner and lighter it is, the smaller the capacity. This is because if thin fabrics are fed according to the nominal capacity, the fabric length will inevitably be too long, the cycle period during dyeing will be long, and the fabric will easily be knotted in the dyeing room due to disorder, resulting in fabric spots.

2. The influence of capstan speed and nozzle pressure
The fabric in the dyeing room is pulled into the nozzle by the capstan. The nozzle is a ring-shaped outlet, and the dye liquid is sprayed from the gap of the nozzle. With the pressure of the nozzle, the dye liquid is sprayed on the rope-shaped fabric, changing the position of the fabric folded due to accumulation in the dyeing room. The speed of the fabric is determined by the capstan speed and the nozzle pressure. In the temperature area where the fabric absorbs dye, increasing the number of cycles of the fabric, that is, increasing the running speed of the fabric, is conducive to the uniform dyeing of the fabric. When the liquid volume is constant, by increasing the dye liquid flow rate (i.e. increasing the nozzle pressure), the number of dye liquid circulations can be increased, the temperature in the dyeing machine and the uniformity of the dye distribution can be increased, the number of dye-fabric contacts can be increased, and the dyeing time can be shortened.
While increasing the fabric speed and the number of dye liquid circulations, attention should be paid to the coordination between the capstan speed and the nozzle pressure, otherwise it will directly affect the product quality. For example, if the capstan speed is too slow and the nozzle pressure is too high, the fabric speed is greater than the capstan speed, which can easily cause fabric scratches; if the capstan speed is too fast and exceeds the nozzle's ability to pass through the fabric, the fabric will accumulate at the nozzle, blocking the nozzle, causing the dyeing machine to stop running, and causing fabric spots.

3. Effect of bath ratio
The bath ratio not only affects the color of the fabric, but also affects the normal operation of the fabric in the dyeing machine. If the bath ratio is too small, the fabric will have difficulty in running, the capstan cannot smoothly lift the fabric from the dyeing room, and the fabric will run slowly. If the bath ratio is too large, the fabric will float on the water surface, easily become disordered and knotted, and the fabric will be dyed. In addition, if the bath ratio is too large, it will inevitably increase the amount of dyes and auxiliaries used, and at the same time increase the labor intensity of the ingredient operation. Therefore, the bath ratio should be determined as small as possible without affecting the operation of the fabric and ensuring the dyeing quality.

4. Effect of dyeing process
(1) The main factors affecting the overflow dyeing quality of active dyes are the dyes used and the addition method, dyeing temperature, the types, dosage and addition methods of salts and alkalis, dyeing time, dye bath ratio, etc. Among the above influencing factors, except for the addition method of dyes, salts, alkalis and bath ratio, the other factors only affect the depth of fabric color, that is, the factors affecting the fixation rate of reactive dyes.
(2) For disperse dyes. When dyeing with disperse dyes at 90℃, the heating rate can be higher, but when it is above 90℃, especially close to 130℃, the heating rate should be controlled to slowly approach the dyeing temperature to avoid uneven dyeing. The dyeing of disperse dyes is strongly affected by temperature, so in the temperature area of ​​dye absorption, increasing the number of cycles of fabric and dye solution can make the dye and temperature in the dyeing room evenly distributed, which is conducive to fabric uniform dyeing.
After dyeing is completed, the temperature should be slowly lowered to avoid fabric wrinkles caused by sudden cooling. When it drops to 100℃, rapid cooling can be used to drop to 80℃, and then overflow cleaning can be performed to further reduce the temperature in the dyeing room. If discharge and water intake are carried out at a higher temperature, it is very easy to form fabric creases, affecting the dyeing quality.