Etherification to improve the performance of lignosulfonate as dye dispersant

Lignosulfonates (SLs) are widely used as dye dispersants. However, they have some disadvantages, including poor high temperature dispersibility and severe fiber staining resulting from the abundant phenolic hydroxyl content in the SL molecules. In this work, etherified lignosulfonates (ESLs) were obtained by using epichlorohydrin to reduce the content of phenolic hydroxyl while increasing the molecular weight. ESLs with lighter color can reduce fiber staining rate by 52% due to whitening by the epichlorohydrin process. The lower adsorption capacity of ESLs onto the surface of fibers can reduce the fiber staining effect, owing to the lower phenolic hydroxyl content. The ESLs also exhibit superior high temperature stability to SL because of their higher adsorption capacity and more rigid adsorption films.