Mechanism Of Fiber Staining Caused By Sulfonated Alkali Lignin And Modification To Reduce Color

So far, there are maily three types of dye dispersants in market, including sulfonated methylene naphthalene, sulfonated phenolic aldehyde condendation and lignin. With the exhaust of fossil resources and and the growing consciousness of environmental protection, the consumption of lignin-based dye dispersants increase rapidly. There are two kinds of lignin-based dye dispersants, one is lignosulfonate and the other is sulfonated alkali lignin. Compared with lignosulfonate, sulfonated alkali lignin is better in heat stability, but its color is deeper, which would not only gives sever staining on polyester fiber, but also distorts the color of dye, especially for the light dye. Therefore, it is essential to study the staining mechanism of sulfonated alkali lignin on polyester fiber and reduce their adsorption interactions and the color of sulfonated alkali lignin, which are beneficial to preparing sulfonated alkali lignin with low staining as dye dipersant.Zeta potential of sulfonated alkali lignin(SAL) and polyester fiber at different pH and the influence of solution conditions on the adsorption and staining of SAL on polyester fiber are investigated. When pH ranges from 1.0 to 12.0, the zeta potential of SAL and polyester fiber are negatively charged, indicating that electrostatic interaction doesn’t exist in the adsoption process. With pH increasing, the color of SAL is darkened, the adsorption amount and strength of SAL on polyester fiber decrease, leading to a light staining, which indicates hydrophobic interaction plays an important role in the adsorption process. With the amount of salt increases, the adsorption amount of SAL on polyester fiber increases but the adsorption strength dereases, resulting in a sever staining. With the amount of urea increases, the adsorption amount and strength of SAL on polyester fiber decrease, leading to a light staining, which indicates hydrogen bonding is also a main interaction in the adsorption process. With temperature increasing, the color of SAL is darkened, the adsorption amount and strength of SAL on polyester fiber increase, resulting in a sever stainingIn order to elimilate the staining of SAL on polyester fiber caused by adsorption, etherification is used to block the phenolic hydroxyl of SAL and reduce the adsorption caused by hydrogen bonding. After etherification, the phenolic hydroxyl and conjugated carbonyl content of SAL derease, o-quinone and methyl content increase, sulfonic content dosen’t change, and the color decreases. When used as dispersant in disperse blue 79, with the decrease of phenolic hydroxyl content, the staining of SAL decreases gradually, heat stability strengthens, dispersibility and the dye uptake have no change.In order to elimilate the staining of SAL on polyester fiber caused by color, H2O2/UV modification is used to reduce the color of SAL. After modification, the phenolic hydroxyl, o-quinone and conjugated carbonyl content of SAL derease, methyl content increases, sulfonic content dosen’t change, and the color decreases by 37.7%, in close to lignosulfonate. When used as dispersant in disperse blue 79, the staining of modified SAL decreases, dispersibility has no change, heat stability and the dye uptake slightly decrease.