양이온화 셀룰로오스 마이크로/나노섬유와 아크릴 발수제를 이용한 판지의 배리어 코팅 연구

초록

In this study, a double-layer coating system to improve the barrier properties of linerboard was developed using either a quaternized cellulose microfiber (Q-CMF) or a quaternized cellulose nanofiber (Q-CNF) layer and a waterborne acrylic water-repellent agent (WAWR) layer. Q-CMFs and Q-CNFs were prepared from bleached hardwood kraft pulp and modified via a quaternization reaction using glycidyltrimethylammonium chloride. The cationic cellulose fibers were applied as a pre-coating layer, followed by top coating with an anionic WAWR. The effects of the degree of fibrillation on coating performance and barrier properties were systematically evaluated. The results showed that Q-CNF exhibited higher viscosity and zeta potential than Q-CMF due to its greater degree of fibrillation and larger specific surface area. In the single-layer coating system, Q-CNF formed a denser coating structure by effectively filling inter-fiber pores, resulting in superior air barrier performance. However, cellulose-only coatings exhibited limited water repellency due to the hydrophilic properties of the cellulose. In the double-layer coating system, the Q-CNF/WAWR-coated paper exhibited the best overall performance. Despite having approximately 20% lower coat weight (6.3 g/m2 ) than the Q-CMF/WAWR coating, the Q-CNF/WAWR exhibited an enhanced burst strength of 11.9 kgf/cm2 and excellent barrier properties. The air resistance increased to 545 s, approximately 12 times that of the uncoated linerboard, while the water repellency achieved the highest grade, R10. FE-SEM analysis confirmed that the Q-CNF effectively sealed the porous paper by forming a dense coating layer. Furthermore, electrostatic interactions between the cationic Q-CNF and the anionic WAWR coating improved coating adhesion and suppressed excessive penetration of the coating liquid into the paper. These results demonstrate that the Q-CNF/WAWR-based double-layer coating system is a promising, recyclable, and environmentally friendly barrier technology for food and consumer goods packaging applications.

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