A study on the recycling of kraft carrier board by dry circular action pre-treatment and alkaline soaking

초록

Kraft carrier board (KCB) is a packaging material that requires strong wet strength, so sizing and wet strength agents are applied in the manufacturing process. Therefore, the kraft carrier board will not get wet and disintegrated easily during pulping. In order to solve the problem of disintegration of KCB, a circular action treatment (CAT) was used, which was designed to solve the problem of shortening of fiber length and poor dewatering caused by beating of old corrugated containers. CAT physically hits raw materials by spinning steel chains. In this study, we tried CAT to improve the disintegration efficiency of KCB. In addition, the effect of alkaline soaking of KCB on the recycling efficiency was analyzed. Untreated KCB showed low disintegration efficiency and even NaOH had little effect on it. Meanwhile, the disintegration efficiency was improved by the dry CAT, and it was further improved by introducing NaOH in soaking treatment. Fiber length and fiber width of KCB were not changed by CAT. However, the recycled sheet based on CAT treated KCB showed high bulk and bad formation due to the relatively low flexibility of CAT treated KCB fibers. Promoted efficiency of disintegration resulted in a significant decrease of shear forces at pulping stage of CAT treated KCB and so fiber flakes didn't have sufficient interfiber frictions after all. Enhancement of the defibration efficiency resulted in a significant decrease in shear force in the pulping stage of CAT treated KCB, thus the fiber flakes did not have sufficient interfiber friction. The physical properties of the recycled KCB sheet were mostly high in stock without CAT treatment. © 2019 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.

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