l. The more water-soluble groups contained in the water-soluble reactive dye molecules of the dye, the more favorable the dye dissolution and dyeing during the dyeing process, and of course, is also advantageous to the washing of floating colors. However, after the dyeing is completed, the "excellent water-soluble group" becomes an unfavorable factor for wet rubbing fastness. This is due to the presence of water-soluble groups, which tends to increase the tendency of the dye molecules to dissolve out of cellulose and dissolve in water. The better the water solubility, the easier the dye is to be disconnected from the fibers. In order to solve this contradiction, after the dyeing is completed, the water-soluble group can be closed by a fixing agent to improve the wet rubbing fastness of the dyed fabric. Type D Sintered Mesh,Expanded Metal Mesh Screen,Sintered Metal Sheet,Metal.Mesh Screen YingKaiMo Metal Net Co.,Ltd. , https://www.ykmmetalnet.com
2. Dye Directness The directness of the dye is mainly related to the size of the molecular weight of the dye, the strength of the polarity, the regularity of the structure, the active groups and their position. The higher the molecular weight, the stronger the polarity, and the better the regularity of the structural morphology, the higher the directness of the dye molecules and the worse the diffusion performance. The dyes are more likely to accumulate on the surface of the fabric and do not easily diffuse into and transfer to the interior of the fiber. Causes too much floating color. If the directness is too low, the fixation rate will be affected. Therefore, the directness of reactive dyes is preferably medium. The size of the directness can be measured from the Rf value and the osmotic test.
3. The reactive groups of the active groups are different, and the stability of the covalent bond formed with the fibers is also different. In general, the higher the reactivity of the active group, the worse the stability after bonding. Different reactive groups, and the formation of covalent bonds with the fiber acid and alkali stability. The ester bond formed by reaction of X-type s-triazine reactive dyes with fibers is poor in acid resistance, and when exposed to acidic gases and moisture, it easily causes breakage of dyes and fibers; the reaction of KN-type vinyl sulfone dyes with fibers is etherified. Bonding, acid hydrolysis is more stable, but it is easy to cause the covalent bond between dye and fiber in the alkaline medium. M, ME reactive dyes with dual active groups have higher acid and alkali stability, but the pH value of the fabric surface can be kept at neutrality. Therefore, controlling the pH value of the cloth surface of the finished color cloth is also important for the wet rubbing fastness of the fabric.