Cold -rolled pile staining, usually ethylene dyes. This is because the active base of the ethylene -type active dye is commonly used, which is very sensitive to alkali. In an alkaline bath, the reaction can be quickly disappeared, and the ethylene radon (-so2ch = CH2) with strong chemical activity can be generated. This has a strong ability to react.
It is worth noting that the cold-rolled pile method is dyed and the dye solution is too alkaline (pH = 12 ~ 13), which is far more than the best solid pH range (10.5-11) of the optimal solid pH of the medium temperature-type active dye. Therefore, although dyeing is down at room temperature (5 ~ 30 ° C) conditions, the hydrolysis rate of dyes is still too fast.
The reason is that in the dye bath in PH = 11, the CELL-O-concentration of cellulose fiber is the highest, and the concentration of OHF is the lowest. At this time, the reaction between dyes and fiber is far faster than the hydrolyzed response between dyes and water. Therefore, the dye is high, the hydrolysis rate is low, and the color is deep. In the dye bath in PH> 1, the higher the concentration of Cell-O- because the stronger the alkali is, the higher the concentration of Cell-O-. Therefore, the dye-fiber is relatively slow, and the hydrolysis response of dyes-water interval is relatively fast. Therefore, ethylene -type active dyes have poor hydrolysis stability in cold dye solution. In particular, it is particularly sensitive to dyeing temperature (referring to the temperature of the flushing and the reaction temperature of the cloth). Even if the temperature fluctuates within the range of room temperature (5 ~ 30 ° C), the hydrolysis rate of the dye has changed significantly. For example, the active blue 50g/LPH = 13.26,15 ℃ is placed for 10 minutes, and the hydrolysis rate is 0.94%. Place 10 minutes at 30 ° C, and the hydrolysis rate is 7.82%. RGB50g/L, pH = 13.5,15 ° C for 10 minutes, hydrolysis rate is 4.34%. Place 10 minutes at 30 ° C, and the hydrolysis rate is 32.72%.
It can be seen that cold staining and the level of dyeing temperature are also the key factor that affects the shades of color. Moreover, it is most beneficial to improving the color of the dyeing and dyeing with lower temperature soaking and stacking. It is not appropriate to deliberately improve the dye temperature.
The natural room temperature is soaked and stacked. Due to the small temperature difference between the inside and outside of the cloth roll or the cloth roll, the color is more consistent, and the dyeing quality is the most stable.
With lower temperature staining, the pH value of the dye bath should be appropriately increased, and the reaction time of the stacking should be extended appropriately. Because the dyeing temperature, the pH value of the dyeing bath, and the stacking time are the three decisive factor of dyeing the cold rolling pile method. There is extremely close interdependent balance between the three. That is, the warm temperature is low, the pH value should be high, and the stacking time should be long; the temperature of the dyeing is high, the pH value should be low, and the stacking time should be short. As long as the three are balanced and produce the best complementarity, the best dyeing effect can be obtained.