Association of cellulose micro/nanofibrils and silicates for cardboard coating: Technological aspects for packaging

Paper coating with cellulose micro/nanofibrils (MFC/NFC) can improve the performance of paper packaging. However, the process cost is high due to the significant energy consumption. The objective of this work was to produce MFC/NFC with pre-treated fibers using calcium silicate (Ca2O4Si) and magnesium silicate (MgO3Si) and evaluate their performance as a coating on cardboard. For the production of MFC/NFC, pre-treatments with Ca2O4Si and MgO3Si reduced energy consumption by ∼30 %. The layers added to the cardboard reduced the water vapor permeability, mainly for the coating with 5 % MgO3Si (∼98 g mm/kPa−1day m²). These characteristics indicate that coated paperboard is suitable for packaging bread, cheese, fruit, and vegetables. Suspensions with 5 % and 10 % Ca2O4Si increased the spread of PVAc, PVOH, and printing ink. The coatings reduced the strength and stiffness of the papers by ∼50 % compared to the uncoated paper due to the wetting and drying cycles. On the other hand, there was an increase in ductility, which potentiated the paper’s formability. Optimizing application and drying techniques for MFC/NFC and silicate coating formulations can improve the mechanical and barrier properties of the coated papers for multilayer packaging.