High barrier sustainable co-polymerized coatings

The goal of this project was to determine the most promising co-polymerized (COP) coating for paperboard for protection against gas and water vapor transmission. The driving force for this was to create a coating that will significantly slow the permeation of water and water vapor through the paperboard, while retaining its mechanical properties. This was accomplished by creating high barrier co-polymerized coatings. This study focuses on the use of modified high shape factor engineered (HSFE) clays. In this study, acrylic co-monomers have been polymerized in the presence of three different, finely dispersed HSFE clays, to prepare the co-polymerized coatings. The wet coating structure was studied using Brookfield and Hercules Hi-Shear viscometers, water retention, and dispersion stability. The dry coating structure was studied using WYKO White Light Interferometry and burn out tests. The cylindrical laboratory coater (CLC)-coated samples were then tested for gas and water vapor permeability. Additionally, the optical and surface properties were determined. The CLC-coated board samples showed almost zero gas permeability and a significant reduction in water vapor transmission rate (water vapor permeability). The water vapor permeability was reduced up to 90% reflecting a one order of magnitude decrease in comparison to a commercially coated sample. The co-polymerized coating with high shape factor and thinner platelet clay displayed the lowest water vapor permeability and the best optical and surface properties, thereby making it the most promising barrier coating for solid bleached sulfate paperboard.