Application of different non-thermal plasma discharges in a roll-to-roll platform for the compatibilization of paraffin-coated Kraft paper with water-based adhesives

Paper packaging stands out for its recyclability and biodegradability, frequently manufactured using repellent coatings to increase its durability in humid environments. However, the use of hydrophobic repellents creates obstacles for its recyclability. This work demonstrates the design and use of cold plasma technologies to improve interaction between samples of paraffin-coated Kraft paper and water-based adhesives. Different systems were prototyped, operating volumetric and surface dielectric barrier discharges (DBD) in a roll-to-roll system. The volumetric plasma generator module (vDBD) achieved a power density of 75 W/cm 3 . The surface plasma generator module (sDBD) achieved a power density of 185 W/cm 3 . The sDBD plasma showed a diffuse behavior, while vDBD plasma showed a filamentary one. SEM images indicated that vDBD treatments generate micrometric damage, while sDBD treatments are more capable of generating nanoscopic etching on the surface of the materials. The sDBD treatments showed superior effectiveness in increasing the water wettability of uncoated samples and similar effectiveness to vDBD treatment for coated samples. Coated Kraft paper samples proved more resistant to the effects of plasma due to the high molecular mobility of the paraffinic surface. T-Peel delamination tests demonstrated superior effectiveness of sDBD plasma in a roll-to-roll system for all samples. Combined sessile goniometry and XPS assays revealed hydrophobic aging mechanisms and preferential effects for the compatibility of each sample. The results indicate high effectiveness of sDBD, acting as a solution for making water-repellent lignocellulosic substrates compatible with water-based adhesives, contributing to the feasibility of environmentally friendly practices in the paper industry.