Polyvinyl alcohol/organic montmorillonite composite coatings applied to paper-based barrier packaging materials

With the continuous improvement of global environmental awareness, the issue of white pollution caused by plastic packaging needs to be effectively solved. Nowadays, the application of sustainable packaging materials has become a developing trend in the packaging industry. In this study, montmorillonite (MMT) was modified to obtain organic montmorillonite (OMMT), which was then combined with polyvinyl alcohol (PVA), after which glycerol, tributyl phosphate, and sodium tetraborate were added to prepare PVA/OMMT composite coatings with high barrier properties, which were successfully coated onto Kraft paper via a facile automatic coating process. Results show that the modification process can optimize the overall properties of the PVA/OMMT composite coating and endow the coated paper with outstanding barrier performance. The oxygen permeability decreased to 14.92 cm³ m^-2·24 h Pa, and the water vapor transmission rate reduced to 2.68 × 10^-12 g cm cm^-2 s^-1 Pa. This was because sodium tetraborate reacted with PVA to form a stable borate ester bond, which enhanced the water resistance of the coated paper. The modified OMMT and sodium tetraborate were combined with PVA to effectively prevent gas permeation. Additionally, the composite coatings exhibited some oil resistance, enhancing the barrier effect of the Kraft paper. These findings suggested that PVA/OMMT-coated Kraft paper had both environmental protection and high barrier properties, offering an innovative approach to developing eco-friendly packaging materials and promoting the application of barrier coatings in paper-based packaging materials.