Analysis of discharge printing technology by baking machine manufacturer

Time：2020-11-30 16:44:51 Source：

Discharge printing has always been a traditional printing process. Reducing agent is often used for discharge printing on reactive dyed fabric. After printing, through a series of production processes such as steaming, washing and drying, the dyed fabric can get a pattern with strong contrast, clear outline, no third color or overlapping between pattern and ground color, and strong three-dimensional feeling. This kind of printing technology has long been mastered by people. The principle is to use reducing agent to destroy the conjugated system in some reactive dye chromophores under hot and humid conditions, so as to fade or color change, or directly destroy the bond between reactive dye and cotton fiber molecules to achieve discharge. This is a chemical reaction, and the reaction is carried out in the steaming process. Through hot and humid steaming, the reducing agent in the printing paste decomposes rapidly and releases the compounds with strong reducing effect, resulting in the fading of reactive dyes or the loss of bonding ability with cotton fibers. Discharge printing is lagging behind that of woven fabric. The reason is that the knitted fabric has loose structure and strong elasticity in warp and weft direction. The printing and dyeing process must be carried out in a series of loose equipment. After discharge printing, special attention should be paid to prevent the chemical agents left on the printed fabric from sticking. It is difficult to process and easy to produce defects. Therefore, the wet hot baking method is used to replace the wet hot steaming method, so that the printing and steaming processes are changed into the continuous one-step process of printing and drying, and the chemical reaction is directly completed by high-temperature baking on the printing machine. The shortening of this process is beneficial to improve the quality rate of printing and dyeing process.