Development and characterization of biodegradable water- and oil-resistant coatings based on derivatized cellulose, sodium alginate, and shellac for paper-based packaging.

As environmental awareness grows, developing non-toxic, environmentally friendly, and biodegradable water- and oil-resistant coating layers using bio-based materials for paper-based packaging has become a key field of research. In this work, sodium alginate (SA) and sodium carboxymethyl cellulose (CMC) were used as the oil-resistant coating layer, while shellac (LAC) and ethyl cellulose (EC) formed the water-resistant coating layer, to produce a water- and oil-resistant coated paper. The effect of the mass ratio of these materials on performance was analyzed, demonstrating that the interaction between SA and CMC enhances the compactness of coating, thereby improving oil resistance. Similarly, the addition of LAC to EC increases coating compactness, which improves water resistance. The resulting coated paper has excellent water resistance (Cobb value: 3.42 g/m) and oil resistance (Kit rating: 12/12) and shows no leakage after holding hot water and hot oil for 30 min, indicating good resistance to both. Additionally, the coated paper demonstrates good mechanical properties, thermal stability, biodegradability and recyclability. The materials used are widely available and low-cost, and the preparation method is straightforward, making this research highly valuable for advancing paper-based packaging materials.