Status quo in oil- and water-resistant paper coatings
A review paper covers a analysis of the water and oil resistance characteristics of several synthetic and naturally occurring polymers and their composites used as paper coatings for food packaging applications.
Paper coatings traditionally rely on petroleum-based compounds like fluoro-compounds, polyethylene, and waxes to alter paper properties such as wettability and oil and water transport. Despite enhancing surface water resistance, their poor recyclability and lack of biodegradability have led to decreased usage, posing threats to the environment, human health, and contributing to greenhouse gas emissions.
Additionally, the use of plastic and fossil-fuel-based materials as barrier coatings in paper-based packaging complicates recycling efforts, increasing overall costs and environmental concerns over non-biodegradable waste accumulation. With growing apprehensions about petroleum-based polymeric packaging and consumer demands for nutritious, long-lasting products, research into alternative packaging materials is gaining traction.
Conversely, innovative environmentally friendly coatings can be developed using biological polymers like polyesters, amino acids, and carbohydrates. These biopolymer coatings serve as potent oil and water protectors, offering sustainable alternatives to chemical-based coatings and preventing water transfer in food products.
However, challenges arise in manufacturing biopolymers due to characteristics such as water-holding capacity, crystallinity, and fragility, limiting their industrial applications. Hence, blending biopolymers with other polymers, fillers, and plasticisers becomes necessary to enhance coating efficacy. The combination of polymers and their modifications with various agents and fillers can produce coatings that improve paper’s water and oil resistance. Discussions also encompass different coating techniques and solvent formulations to optimise coating solutions.
