Lignin-based sustainable packaging solutions

Oil-based barrier coatings were replaced by lignin-based coatings, and packaging materials made of recycled fibers were reinforced by lignin addition. A solvent fractionation method was developed to produce pure and homogeneous lignin fractions with increased thermoplasticity compared to the starting material. Another way to successfully increase lignin's thermoplasticity was chemical modifications by esterification reactions. Lignins esterified with fatty acids formed films without any external plasticizers. Lignin fatty acid esters coatings on paper board reduced significantly water vapour and oxygen transmission rates. Barrier properties against water vapour were as good as, or even better, than those of commercial PLA (poly lactic acid). Unmodified softwood and hardwood kraft lignins precipitated on recycled fibers increased strength, bonding and water resistance of packaging materials, e.g. corrugated boards. Accordingly, at least 20% of fibers can be replaced by lignins. The carbon footprint results for two new lignin-based products indicated reductions in greenhouse gas emissions by including lignin either in the furnish to compensate fibres and gain lighter weight or as barrier material to replace oil-based barrier coatings.