Improving the Barrier Properties of Paper to Moisture, Air, and Grease with Nanocellulose-Based Coating Suspensions

Abstract

Food packaging manufacturers often resort to lamination, typically with materials which are neither non-biodegradable nor biobased polymers, to confer barrier properties to paper and cardboard. The present work considers a greener solution: enhancing paper’s resistance to moisture, grease, and air by aqueous coating suspensions. For hydrophobization, a combined approach between nanocellulose and common esterifying agents was considered, but the water vapor transmission rate (WVTR) remained excessively high for the goal of wrapping moisture-sensitive products (>600 g m−2 d−1). Nonetheless, oil-repellant surfaces were effectively obtained with nanocellulose, illite, sodium alginate, and/or poly(vinyl alcohol) (PVA), reaching Kit ratings up to 11. Regarding air resistance, mineral-rich coatings attained values above 1000 Gurley s. In light of these results, nanocellulose, minerals, PVA, pullulan, alginate, and a non-ionic surfactant were combined for multi-purpose coating formulations. It is hypothesized that these materials decrease porosity while complementing each other’s flaws, e.g., PVA succeeds at decreasing porosity but has low dimensional stability. As an example, a suspension mostly constituted by nanocellulose, sizing agents, minerals and PVA yielded a WVTR of roughly 100 g m−2 d−1, a Kit rating of 12, and an air resistance above 300 s/100 mL. This indicates that multi-purpose coatings can be satisfactorily incorporated into paper structures for food packaging applications, although not as the food contact layer.

Stabilization of Beeswax-In-Water Dispersions Using Anionic Cellulose Nanofibers and Their Application in Paper Coating

“…Given this dependence on the concentration of nanofibers, it is reasonable to state that this agent is the main contributor to the air barrier properties. Nonetheless, in previous works, coating suspensions consisting only of TOCNFs attained a lesser improvement [ 45 , 51 ]. Hence, glycerol played an important role, acting on nanofibers as a plasticizer and easing their even distribution onto paper.…”

Biomaterials for Drug Delivery and Human Applications

“…The last member of this classification is polyethylene (PE), a non-biodegradable polymer [198,199]. It is used in various applications, including plastic bags and containers; polypropylene (PP) is another common non-biodegradable polymer used in products such as packaging, automotive parts, and textiles; polyvinyl chloride (PVC) is a versatile synthetic polymer but is not biodegradable.…”

Advances in Cellulose-Based Packaging Films for Food Products

“…Hence, films made from cellulose micro/nano fibrils are known to have low thermal expansion coefficient, high transparency and good mechanical characteristics [24]. Cellulose nanofibril films may even show better oxygen and water vapor barrier ability than some petroleum-based polymers [25]. Furthermore, mechanical properties are important for handling and packaging applications to interpret the durability and sustainability of materials.…”