Lignin fractionation towards improved rosin emulsification behavior and advanced liquid packaging board sizing performance

The heterogeneity of lignin, due to its intricate chemical composition and inconsistent molecular weight distribution across various sources, would result in inconsistent materials with unpredictable characteristics, thus presenting a significant obstacle and impeding the advancement of lignin-based products. The need for innovative rosin/lignin-based sizing agents for liquid packaging board (LPB) products has yet to be fulfilled, stimulating ongoing research efforts in this area. Herein, to tackle the urgent challenge posed by the lignin inhomogeneity and its effect on sizing performance, we propose a comprehensive approach for the production of fractionated lignin-modified rosin sizing agents for liquid packaging board (LPB) with improved sizing characteristics. This study first fractionated three lignin components from wheat straw-derived lignin and utilized them as adaptable surfactants in the manufacture of cationic dispersion rosin sizing agents. The resulting agents were analyzed and evaluated for their utilization in LPB sizing process, exhibiting improved homogeneity, molecular weight, and hydrophilic group content. The obtained fractionated lignin-modified rosin sizing agents displayed outstanding sizing performance and desirable stability. Additionally, these agents enhance the mechanical and optical properties of LPB products. This study proposed a novel and valorized approach to apply lignin biomass with a fractionation and sustainable method to prepare series lignin-modified rosin sizing agents and their great potential in liquid packaging board applications.