Convertibility and Water Resistance of Wax-based Spray Coating with the Addition of Polylactic Acid

Abstract

Petroleum-based plastic coatings are used to create moisture barriers and heat-sealable layers on paperboard. Despite their good convertibility and barrier properties, the use of sustainable biobased polymer coatings as alternatives has attracted interest due to environmental concerns. In this study, the convertibility and water resistance of bio-based multilayered coating composed of biowax and polylactic acid (PLA) were investigated. Convertibility of the coatings was studied through heat-sealing experiments and by evaluating their durability when they were subjected to high stresses during creasing and folding. Surface imaging was performed to evaluate film formation and coating integrity. The wettability and water absorption properties of the coatings were also investigated. Different coating compositions resulted in different film formation processes, surface appearances, and water absorption. The presence of wax in a coating increased its hydrophobicity and reduced its water absorption already with the smallest addition in the coating. However, a high wax content in the coating caused defects in the coating layer, whereas the addition of PLA increased the convertibility of the coated material. This indicates that water resistance, heat sealability, and convertibility can be simultaneously achieved by optimizing the composition of wax and PLA coatings.

Keywords

• bio-based coating
• convertibility
• heat sealing
• water resistance