The key to the success of batik printing with one bath dyeing of reactive dyes and chrysophanol is to control the hydrolysis of reactive dyes. The hydrolysis degree of reactive dyes is mainly related to the structure of dyes, the pH value of dye solution, temperature and time. Therefore, the following points should be paid attention to when underprinting:
(1) K-type reactive dyes with low hydrolysis degree in alkaline medium should be selected for reactive dyes.
(2) The caustic soda for dissolving tryptophan should be controlled at the lower limit, and the total amount of caustic soda should not exceed 59/L.
(3) Reactive dyestuffs should be added before use, and cold water should be added as much as possible to reduce the temperature of dyeing solution, generally less than 50 C. The dyeing solution should be used with matching and should not be placed for a long time.
(4) No baking soda is added in the dyeing solution, because the free alkali in the dyeing solution is enough to meet the needs of fixing reactive dyes. In addition, because the reactive dyes are fixed by steaming after printing, and most of the color bases are not steaming resistant, in order to prevent the color change of ice dyes, it is necessary to add anti-icing salt Sl09/L0 to the pulp, which has a light and ugly active ground color and no reactive dyes in the printing color, to use fast steaming.
