What is Discharge Printing?

What is Discharge Printing?

One of the printing methods. On the dyed fabric, the paste containing reducing agent or oxidizing agent is printed to destroy the ground color and partially expose white ground or colored patterns.

There are many ground color dyes that can be used as discharge dyes, such as insoluble azo dyes, reactive dyes, direct dyes and so on. Since the vat dye itself is in the medium of a strong base reducing agent, it is most suitable as the color discharge dye in the ground color discharge dyeing of the above-mentioned dyes. The discharge printing process is complicated, prone to defects and high cost. However, the effect of discharge is better than that of anti-dye printing, with clear contours and no white edges. Because this printing method mostly uses carved white powder, it is also called carved printing.

The process of printing ground-colored fabrics with a color paste containing a discharge agent is called discharge printing. Discharge printing can achieve two effects: white discharge and color discharge. Discharge printing fabrics have full color, fine and precise patterns, and clear contours, but they are expensive, long and complicated in production processes, and occupy a large area of equipment, so they are mostly used for high-end printed fabrics. All kinds of dyes containing azo groups will break bonds under the action of strong reducing agents, which will decolorize them.

The discharge agent is mainly a strong reducing agent, kaolin, in addition, it also includes a discharge aid and an alkali agent.

In order to improve the discharge effect, a discharge aid is often added to the discharge printing paste. Anthraquinone and whitening agent W are generally used, of which anthraquinone is widely used.