In the dyeing of polyester and its blended knitted fabrics, printing and dyeing workers put forward the problem of the use of dyes, mainly the discoloration of disperse dye polyester. For example, the hue of disperse red FB changes to purple, and the hue of disperse deep blue H-GL changes to brown. Disperse Red FB has a bright hue and good dyeability, but when metal ions such as copper and iron are present in the dye bath, it will combine with the dye to form a metal complex structure, making the dyed shade bluish and purple, and poor dyeability.
In addition, certain metal ions in the dye bath can trigger redox reactions under acidic and high temperature environments, destroying the structure of the dye, and directly causing no coloring.
The solution is:
①Add a chelating dispersant to the dye bath to complex the metal ions in the water so that it does not affect the structure of the dye.
② Disperse red ACE with similar hue can be used instead, the latter is more stable than the former.
Disperse dark blue H-GL is (CI. Disperse Blue 79). Because of its deep dyeing and sublimation fastness, it has been used for a long time, but occasionally the problem of large color light deviation occurs. This is mainly due to the fact that the disperse dark blue H-GL is very sensitive to the pH value of the dyeing bath. Generally, the pH value of the dyeing bath is controlled at 4.5-5, and the pH value is greater than 7, and the color light will change greatly, from reddish to brown, or even change. It is khaki with a great drop in depth. Preventive measures: The amount of acetic acid used for dyeing must be accurate, and the dyeing bath ratio must be strictly controlled.