IMPROVING BARRIER AND STRENGTH PROPERTIES OF PAPER BY MULTI-LAYER COATING WITH BIO-BASED ADDITIVES

This study aims to evaluate the application potential of water soluble chitosan derivatives and microfibrillated cellulose (MFC) as barrier and mechanical strength additives in coating formulas for packaging paper grades. Three water soluble chitosan derivatives with specific functionalities were obtained in laboratory (alkyl chitosan – ACh, quaternary chitosan – QCh and carboxymethyl chitosan – CCh) and applied on solid board surface as single component or in combination with MFC. Coated board samples were characterized in terms of water barrier properties (contact angle, Cobb 60 index), water vapour transmission rate (WVTR), tensile strength properties and surface structure (SEM images). The results have shown the ACh applied alone or in combination with MFC improves the water and water vapour barriers, the CCh improves tensile strength properties (15%-20%) and WVTR (~30%), while the QCh gives moderate effects on the water barrier and strength properties.