An efficient chemical pulping method for optimal resource utilization and improved pulp properties in packaging-grade paper production

Highlights • Green wood chip with high alkali impregnation showed efficient pulping • This pulping technique required low energy input for obtaining the same kappa number • High alkali impregnated pulp (HAICK) showed more selective delignification • HAICK pulp showed better physical and mechanical properties • The hot-pressed handsheet of HAICK showed higher tensile strength • This pulp is promising to use in packaging paper production Reducing the loss of cellulosic material during pulping remains a significant challenge for the pulp and paper industry. Achieving high-kappa pulp with minimal rejects is crucial for the efficient utilization of wood resources. This study explored the application of high-alkali impregnation combined with green (non-dried) wood chips as a strategy to achieve these objectives. The results demonstrated that this method yields a pulp with a 52.3% yield, an exceptionally low reject content of 0.2%, and a kappa number of 54.2. Furthermore, the hot-pressed (250°C) hand sheets produced from the high-alkali-impregnated, high-kappa pulp (HAICK-50) exhibited an improved tensile index of 111 kN·m/kg compared to 96.9 kN·m/kg and 108 kN·m/kg for the pulp of reference cook with kappa 30 (REFCK-30) and kappa 50 (REFCK-50), respectively, highlighting the potential of this approach to improve both material efficiency and product quality in the pulping process.