국산 리파이너 바를 이용한 리파이닝 효과 연구

Abstract

Bleached kraft pulps with different dimensions were refined by the refiner plates designed and manufactured for this study. One pulp has a length-weighted mean fiber length of 2.90 mm and a coarseness of 15.5 mg/100 m. Another pulp has a length-weighted mean fiber length of 0.68 mm and a coarseness of 9.25 mg/100 m. The long- and thick-fiber pulp (Pulp I) was refined by the plate of coarse fillings with lower cutting edge length (CEL), and the short- and thin-fiber pulp (Pulp II) was refined by the plate of fine fillings with higher CEL. The fiber length of pulp I was sharply reduced at the beginning of refining, and, on the other hand, that of pulp II was more slowly reduced. Coarse fillings against Pulp I led to more cutting rather than fibrillation, and fine fillings against Pulp II promoted more external and internal fibrillation. Due to the dimensional characteristics, the long and coarse fibers required more refining energy in gaining the designated freeness level than did the short and thin fibers. At a given refining amount, the finer fillings led to the slower increment in tensile strength than did the coarser fillings. However, tear strength of pulp I sharply improved at first and thereafter rapidly dropped, whereas pulp II steadily increased and then gradually decreased with prolonged refining. Based on these results, more gentle refining for the pulp such as pulp II was required to obtain desirable fibrillation and energy savings, and therefore a novel manufacturing technology such as a laser technology and diffusion bonding differently from casting should be applied to develop much finer filling with the combination of high cutting edge length and hydraulic capacity.