Cashew Phenol Modified Lignosulfonate Strategy for the Preparation of High-performance Dye Dispersants.

Lignin-based dye dispersants (LDD), as one of the most common lignin resource end-application product, is difficult to meet the rapidly developing needs of modern fiber dyeing due to their inherent structural defects. The efficient upgrading and modification of LDD is of great significance to the value-added application of lignin resources and the expansion of LDD sinking market. In this study, using industrial kraft lignin as raw material, cashew phenol was introduced into lignosulfonate in the form of CC bonds by ingenious utilizing the structural characteristics of lignin disordered condensation. Aromatic ring in cashew phenol could provide sufficient sulfonic acid group grafting sites, while C₁₅ fatty chain could enhance steric hindrance effect. In the dispersibility test, the dispersing power showed 99.09 %, and the low/high temperature dispersion (LTD/HTD) were 5 s/4 and 6 s/4, respectively, higher than the dispersibility level of LDD in the market, has great commercial value and industrial potential. Combined with FTIR, ¹H NMR, GPC and ICP, the structural properties of lignin were analyzed in detail, and the degree of sulfonation-condensation was balanced-optimized. The CC bond condensation process between cashew phenol and lignin was revealed, and the mechanism of action on dye particles was elucidated.