The role of additives in polycondensation dye printing

1 Urea: It is a co-solvent and a hygroscopic agent. It can expand the fiber during steaming, which is beneficial to the penetration and diffusion of dyes. It is beneficial to improve the rubbing fastness of dyes on fabrics.
2 Thiourea: It is a fixing agent, so that the dyes are vaporized under alkaline conditions to produce intermolecular polycondensation of dyes into vulcanized polycondensates and fixed to the fibers. Fixing agent can also be used sodium sulfide, but it is not suitable for printing, because it will lead to premature condensation of the dye at room temperature, resulting in instability of the color, resulting in sedimentation, calyx and other defects.
3 Sodium bicarbonate: It is an alkali agent to facilitate the shedding of water-soluble groups of dyes and the polycondensation of dyes. If sodium carbonate is used, the alkalinity is strong and the fixation is fast. The steaming time can be shortened, but the stability of the color paste is reduced. The alkali agent must be added to the color paste before use.

Printing Paste Preparation and Cleaning Source: China Washing & Finishing Industry Information Center Published Date: 2005-12-04
The preparation of printing paste needs to be carried out according to the specified time and operating procedures, and the consistency of the paste should be ensured as much as possible. Preparation of paint printing paste is easier than dye printing paste. For special printing pastes formulated with dye printing pastes and paint printing pastes, it is necessary to consider that the pastes are easy to wash in high-speed water washing, but also to consider it with a reasonable balance of print fastness, feel and other issues, and to maximize the process requirements.

Source: China Washing & Dyeing Industry Information Center