Effect of Fiber Structure on Edge-Wicking in a Highly Sized Paper

摘要

Coffee edge-wicking testing was conducted on two groups of highly sized cup stock manufactured at two mills with similar manufacture processes, but with vastly different local fiber sources. Although the Hercules Size Test (HST) indicated similar internal size levels between the two types of board, the edge-wicking behavior was noticeably different. Analysis of fiber structure revealed that the board with more edge-wicking had fibers with thicker fiber walls, which kept the fiber lumen more open after pressing and drying on a paper machine. It was demonstrated that liquid penetration through voids between fibers in a highly sized paper board was limited, because the fiber surface was well protected by the presence of sufficient sizing agent. Nevertheless, freshly exposed fiber walls and lumens at the cut edge of the sheet were not protected by sizing material, which facilitated edge-wicking. The correlation between fiber structure and edge-wicking behavior was highlighted in this work to inspire development of novel sizing strategies which protect the freshly cut edge of the sheet from edge-wicking.