Lignocellulosic nanofibers for the reinforcement of brown line paper in industrial water systems

Abstract

The addition of nanofibrillated cellulose in paper production requires attention to its dispersion and retention during the paper forming process, and this is commonly facilitated by the use of retention agents. The performance of retention agents, which commonly have a cationic charge, is affected by the presence of dissolved and colloidal substances in the process water. In the process of paper production at an industrial level, especially when using recycled paper, there are a large amount of dissolved and colloidal substances in the water. A high proportion of these substances are negatively charged and are commonly referred to as anionic trash. Its presence increases the conductivity and charge density of the water, and this has a negative influence on the retention of cellulose nanofibers. In brown line paper production, some fibers have already been refined in at least one previous papermaking cycle. In this sense, recycled fibers have a reduced capacity to benefit from refining as they have suffered morphological damage. On the other hand, the addition of lignocellulosic nanofibers in the production of brown line paper has been found helpful to improve its properties and extend its lifespan. In this work the influence on the retention of nanofibers of different anionic trash levels in the water has been evaluated. The results showed its viability as a reinforcing agent in waters with high anionic trash content, through the addition of an anionic trash catching system.