Representative effects of valley beater and disk refiner on pulp fibers

Refining or beating is adopted to improve bonding ability of pulp fibers thereby forming a strong and uniform paper sheet. The refining effects on pulp fibers include fiber shortening and fines generation as well as internal and external fibrillation. In general, we have been using a laboratory Valley beater instead of refiner in order to estimate refining effects on pulp fibers. Since the Valley beater is different from a disk refiner in refining mechanism, we needed to understand their representative results using the same pulp fibers. For refining of long fibered pulp, the Valley beater created shorter mean fiber length and more fines than did the disk refiner equipped with a wide bar width. On the other hand, for refining of short fibered pulp, the disk refiner equipped with a narrow bar width generated longer mean fiber length and fewer fines than did the Valley beater. For strength properties, the Valley beater contributed to better development of sheet strength than did the disk refiner. In conclusion, it must be kept in mind that the amount of refining depends upon pulp types, refiner types, plate bar pattern, stock consistency, and so on.