New eco-friendly coating formulations to improve strength and physical properties of recycled paper boards for sustainable packaging applications

This research work emphasizes the applicability of eco-friendly clay-based coating formulation on recycled paperboards to improve strength properties. Two new clay-based coating formulations were prepared using china clay (F1) and montmorillonite clay (F2) as the main constituents and acronal, sorbitol, and ammonia as other additives. The coating was performed using K bar coater at three different thicknesses (4, 10, and 15 µm). The strength and physical properties of recycled paperboard coated with formulations F1 and F2 were compared. It was found that the strength properties of recycled paperboards coated with formulation F1 were higher, and the physical properties (porosity and cobb) were lower than formulation F2. Scanning electron microscopy (SEM) analysis indicated reducing pores and unevenness on the surface of recycled paperboards when coated with formulation F1. The atomic force microscopy (AFM) images of the recycled paperboards coated with formulation F1 revealed improved surface smoothness for a coating thickness of 4 µm.