1. Methods and ways to improve the color fixing rate
Improving the fixation rate of reactive dyes can be considered from the selection of dyes and the dyeing process: dyes with high directness and low reactivity have a large amount of adsorption by fibers and are not easy to be hydrolyzed. Fixation rate: The temporarily soluble reactive dyes with sulfate as soluble group will become insoluble lakes and fixed on the fabric when hydrolyzed, so that the stains can be converted into fixed colors, and the fixation rate can reach 80% ~ 95% ; Multi-reactive group dyes are not easy to be hydrolyzed, and their fixation rate is very high, so they are the most used reactive dyes.
In terms of dyeing process, using lower temperature and dyeing under neutral conditions can improve the directness of dyes and reduce the hydrolysis of dyes. In the dyeing process, a small bath ratio is used, and neutral electrolytes are added to promote dyeing; appropriately prolonging the dyeing time can improve the fixing rate.
2. Ways to improve dye fastness of reactive dyes
2.1 Correct selection of dyes
Color fastness is closely related to the structural properties of dyes. The selection of dyes should consider the following points:
(1) The reactivity between the dye and the fiber is strong, so that the two are prone to covalent bonding;
(2) The fixation rate should be high;
(3) The stability of acid and alkali is better;
(4) The bond energy of the covalent bond of the dye-fiber is high, the chemical stability is better, and the bond is not easy to break;
(5) The ability of antioxidants and reducing agents is stronger;
(6) The compatibility and compatibility of color matching dyes are better.
Reactive dyes with multiple reactive groups have high fixation rate and good color fastness, which should be the first choice for dyes. In addition, some reactive dyes with good color fastness in certain aspects, such as dyes with good light fastness; dyes with high light fastness and good stability to repeated oxidative washing; suitable for continuous dyeing and high color fastness dyes, etc. Use to choose to use.
2.2 Purification of water quality
Reactive dyes can combine with calcium, magnesium ions and other heavy metal ions to form insoluble metal dyes. These metal dyes will gradually adsorb on the surface of the fiber, resulting in color spots or floating colors. These floating colors will prevent the dyes from diffusing into the fiber and reduce the dyes. Dyeing rate, and make the fabric shade variation, brightness and color fastness decreased. Therefore, it is necessary to use a water purification material that meets the dyeing requirements, or add a chelating water softener to the water before the chemical material to purify the dyeing water quality.