Effect of the wet-end addition of cationic cellulose nanofibril on paper strength

Abstract

Because cellulose nanofibrils (CNF) made from bleached kraft pulp are small and contain anionic carboxylic acids, papermakers can not expect a high retention of CNFs in the pa- permaking process. If the CNFs are cationic, they can be retained on the anionic cellu- losic fibers and improve the paper strength. In this study, we manufactured cationic CNFs by quaterizing the CNFs made from bleached hardwood kraft pulp (HwBKP). After the cationic CNFs were prepared, their particle size, zeta-potential, and fiber width were measured. Handsheets were made by adding cationic CNFs to the stock containing softwood bleached kraft pulp (SwBKP) and HwBKP, and the strengths of the handsheets were analyzed. The zeta-potential value of the CNFs changed from negative to positive after quaterization, but the particle size and fiber width of the CNFs did not change significantly. The CNFs improved the strength of the handsheets, linearly, and the paper strength was greater in the cationic CNF than the untreated CNF. It was concluded that cationic CNF was more effective at improving the paper strength by increasing the fiber bonds than the untreated and negative CNF. ? 2018 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.