Study of Mixed refining behaviors of softwood kraft pulps and hardwood kraft pulps using different bar fillings

Abstract

Mixed refining using a narrow and coarse bar filling was applied to the mixing furnishes of long fibers and short fibers. According to different bar fillings, pure HwBKP in the narrow filling showed a faster drop in freeness than the mixed furnishes, and pure SwBKP in the coarse filling showed the slowest drop, differently from the mixed furnish. The mixed furnishes with more long fibers caused their mean fiber lengths to be shorter in both plate fillings. The increase of water retention values in the mixing furnishes was more affected by the amount of short fibers in the mixed furnish, not by the plate filling types. For physical properties of paper according to co-refining, better improvement was acquired in the coarse filling rather than in the narrow filling. In particular, the amount of long fibers in the mixed furnish contributed to the better improvement of physical properties in the same refining energy regardless of the plate fillings. Finally, it could be concluded that refining of mixed furnishes preferred the coarser bar filling to the narrower bar filling in developing fiber and paper properties. ? 2018 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.