Factors Affecting Dyeing of High Temperature and High Pressure Dyeing Machine

1. Temperature

Temperature is a key factor for high temperature and high pressure dyeing machines. Increasing the temperature can increase the dyeing % of disperse dyes. However, when the temperature reaches above 130 degrees, the dyeing percentage of most disperse dyes no longer increases significantly. If the temperature is too high, the polyester bond will be hydrolyzed, resulting in a decrease in the elasticity and strength of the fiber, and a poor shade. Therefore, 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 level dyeing property and high color yield, but also controls the pH value of the dyeing bath within the weak acid range of 5-6. The disperse dyes are quite stable, so the color is very bright. In order to make the dyes evenly absorbed by polyester, the heating rate must be strictly controlled. When the temperature rises to the specified temperature, it should be kept warm for a period of time to ensure that the dye is fully diffused and penetrated. The heat preservation dyeing time is generally 30-60 minutes, the light color can be shorter, and the dark color can be longer. After dyeing, the temperature should not be lowered too fast, otherwise it will affect the handle and cause creases.

2. pH value

Many disperse dyes will be hydrolyzed under high temperature and alkaline conditions, so it is advisable to control the high temperature and high pressure dyeing bath under acidic conditions.

3. Application of additives

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