2025

Lankinen Kai; Merabtene Mahdi; Saukkonen Esa; Leminen Ville

Increasing concerns regarding plastic waste and its impact on the environment have prompted a global trend to replace plastic films with fiber-based packaging solutions. Though the heat-sealing of polyolefin films provides a simple approach for realizing flexible packaging, paper does not have the natural attributes required for such applications. Therefore, paper sealability must be achieved by other means such as coating or varnishing. This study accordingly investigated the basics of imparting heat-sealability to packaging paper using overprint varnish applied with a lab coater simulating flexographic printing. The sealing and grease resistance properties of the resulting paper were compared with those of commercially available polyethylene dispersion-coated paper and oriented polypropylene/polyethylene laminate. The results confirmed that sufficient capabilities were realized using the proposed method; though the varnished paper exhibited a lower seal strength than the reference plastic films, it exhibited adequate properties for package sealing regardless of applied temperature. These observations were subsequently discussed to inform recommendations for further investigation and development.