Discharge Printing Technology Of Denim

Pretreatment

Pretreatment includes desizing, soaping, brittleness prevention and discharge of black denim printing Especially important.

The original yarn of black warp and white weft denim warp is wetted with penetrant and caustic soda. After several times of dipping and rolling, the sulfide black dye is oxidized. After dyeing, it is washed warm, treated to prevent brittleness, dried, and then sized for weaving. After finishing, it is also treated with light sizing.

In addition to conventional desizing, soaping and brittleness prevention must be added to the pretreatment of black denim printing.

Black denim is characterized by customized suits with black color, and the dyeing depth is as high as lO% - l2%. When pdmgtlb is dyed at such a high concentration, the dye fixation rate is relatively low. After dyeing, warm water washing cannot clean the unfixed dyes, and there are many floating colors on the cloth. During discharge printing, numerous floating colors and discharge agents act to reduce discharge capacity, increase discharge difficulty, and thus affect discharge effect.

For this reason, black must be removed by soaping Denim Floating color on the surface to improve the discharge effect. In addition, during post press washing, the floating color concentration in the washing solution will not be too high, reducing the possibility of floating color re adhering to white and color patterns, so it is important to remove floating color before printing.

Sulphide black fabric has serious brittleness. Discharge agent JN is treated in acid medium at high temperature and humidity for a certain time to complete discharge. At the same time, it can not be customized hat to avoid serious brittleness of black denim. Therefore, the brittleness of the fabric must be prevented before printing to minimize the brittleness of the fabric.

The discharge agent JN prepared by thermal method is dissolved in hot water at about 80 ℃, added to the acid resistant paste, stirred evenly, and then added with the extraction aid S to stir and dissolve. The discharge agent JN prepared by cold method is directly put into the pulp to be stirred and dissolved, and then the extraction aid S is added to be stirred and dissolved.

The temperature of hot method is higher than that of cold method. According to general rules. If the concentration of reactants is constant, the reaction rate will increase 1-2 times for every 10 ℃ increase in temperature. In acid medium, the temperature of discharge paste exceeds 30 ℃. It will accelerate the premature and excessive decomposition of discharge agent JN, and its loss will be more than 10%. Therefore, the cold method is superior to the hot method, and its discharge pulp has low temperature, simple operation and little loss.

Preparation of paint dyeing discharge paste coating Direct printing.