Working principle of high temperature and high pressure dyeing machine

1. Temperature

Temperature is a key factor in high temperature and high pressure dyeing. Increasing the temperature can improve the dyeing % of disperse dyes. However, when the temperature is as high as 130 degrees or more, the dyeing percentage of most disperse dyes no longer increases significantly. If the temperature is too high, the polyester ester bond will be hydrolyzed, which will lead to the elasticity and decrease of the fiber, and the color difference. Therefore, the high temperature and high pressure dyeing is generally limited to no more than 145 degrees. Generally, the dyeing temperature is controlled between 125-130 degrees. Dyeing at this temperature not only has good levelness and high color yield, but also controls the PH value of the dye bath within the weak acid range of 5-6. Disperse dyes are quite stable, so the color is very bright. In order to make the dye evenly absorbed by polyester, the heating rate must be strictly controlled. When the temperature rises to the specified temperature, the dyeing should be kept for a period of time to ensure sufficient dispersion and penetration of the dye. The insulation dyeing time is generally 30-60 minutes, the light color can be shorter, and the dark color can be longer. After dyeing, the cooling should not be too fast, otherwise it will affect the hand feel and form creases.

2. PH value

Many disperse dyes will be hydrolyzed under high temperature and alkaline conditions, so high temperature and high pressure dye baths are suitable for controlling acidic conditions.

3. The use of additives

During high temperature and high pressure dyeing, in order to make the dyes stably disperse in the dye bath, and at the same time to achieve a leveling effect, an appropriate amount of dispersant and leveling agent can be added to the dye bath.