The Effect of Coating Temperature on the Mechanical and Adhesive Properties of Polypropylene-Coated Kraft and Duplex Papers

This study explores the impact of coating temperature on the mechanical and adhesive properties of Polypropylene (PP)-coated Kraft and Duplex papers, with a focus on sustainable packaging applications. PP coatings were applied at three different temperatures, 150°C, 200°C, and 230°C, using a hot press method. The mechanical properties, including tensile strength and peel strength, as well as the surface morphology of the coated papers, were evaluated. The results revealed that both the tensile and peel strength significantly improved as the coating temperature increased, with the best performance observed at 230°C. For the Kraft paper, the tensile strength increased from 2,548.1 kPa at 150°C to 2,748.8 kPa at 230°C, while the peel strength increased from 122.6 N to 151.5 N. The duplex paper showed a similar trend, with the tensile strength rising from 1,570.0 kPa at 150°C to 1,836.8 kPa at 230°C and the peel strength increasing from 107.9 N to 132.1 N. The Scanning Electron Microscopy (SEM) analysis revealed that higher temperatures resulted in more uniform PP coatings, leading to improved adhesion. These findings suggest that the reduced polymer viscosity at higher temperatures enhances the polymer penetration, improving the bonding to paper fibers. This study highlights the potential of temperature optimization to enhance the performance of PP-coated papers, contributing to the development of sustainable packaging materials.