Abstract:

In order to enhancing the dye fixation rate of reactive dye in pad-steam dyeing process, the influence of the fabric heating rate on the dyeing properties of reactive dye was investigated to search the method of salt-free dyeing with high fixation rates. The temperature of fabric in the steaming process was calculated using the thermal conductivity and volumetric heat capacity measured. The influence of dye liquor composition and fabric pickup on the variation of fabric temperature was investigated. Besides, the colour performance and fastness of the dyed fabrics as well as the dye fixation rates were studied. The results indicate that the fabric heating rates are increased by adding the Na2SO4 into padding solutions, thereby enhancing K/S value and dye fixation rate. However, it does not meet requirements of the salt-free dyeing. Increasing the pickup resulted in increasing the thermal conductivity and volumetric heat capacity of fabrics, but decreasing the temperature of fabric. The K/S values of dyed fabrics and the dye fixation rates increased as the fabric pickups decreased, which is substantially in accordance with the variation of the fabric heating rates. The phenomenon confirmed that enhancing fabric heating rates is conducive to improving the dyeing properties of reactive dye. Reducing the fabric pickup can increase the fabric heating rates, which is an effective way to realize salt-free dyeing in pad-steam dyeing.

Key words: cotton fabric, reactive dye, salt-free dyeing, heating rate, dye fixation rate