Spray application of polysaccharide-based barrier coatings on paper and board

Description

Paper and board are well-established materials in packaging applications due to their high recycling rate and biodegradability. Because of the hydrophilic and porous nature of paper, modifications are necessary to achieve desired barrier properties. Especially in food packaging applications, barriers against gases, grease and oil are required. In conventional packaging these barrier properties are often achieved by the application of layers made from non-renewable materials such as plastics or metal films.
However, these composite materials pose a significant problem for the environment and for the recyclability of fiber-based packaging materials. Naturally occurring biopolymers, such as alginate and chitosan, have shown to be good oxygen and oil barriers which can be applied on paper substrates. Still, the application of these polysaccharides poses several challenges to state-of-the-art paper coating equipment because of the difference in properties compared to conventional paper coating materials. For instance, these biopolymers usually have a significantly higher viscosity already at low solids content.
The research objective is to evaluate the potential of spray application of polysaccharides to overcome some of the difficulties conventional paper and board coating methods have when applying these new materials. Coating results and barrier properties in general depend strongly on the solution properties, the base paper substrate as well as the drying process. Therefore, one approach to optimize the spray application is to adapt the base paper. Selected polysaccharide-based and a synthetic reference material are applied by spray coating on four different base papers and the resulting barrier properties are compared to samples coated with a film press representing a conventional paper coating unit. Different drying methods are also compared to prevent defects in the barrier coating caused by the drying process. We also evaluate the application of the spray coated barrier on the wet web during paper production to allow multi-layering, to save drying energy and to potentially enable an installation in existing industrial processes.
Whilst several challenges remain, our results show that spray applications of polysaccharide-based barrier materials are a promising way to apply high viscous biopolymer solutions on paper for food packaging applications.

Period	18 Mar 2024
Event title	ACS Spring 2024: Many Flavors of Chemistry
Event type	Conference
Location	New Orleans & Hybrid, United States, LouisianaShow on map
Degree of Recognition	International