In this study, commercially available softwood lignin was esterified with tall oil fatty acid (TOFA) and studied as barrier material in fibre-based packaging material. The lignin was esterified to different degrees of substitution and the chemical analyses of the resulting samples were carried out by FTIR, TMAH thermochemolysis GC–MS, 31P NMR and SEC. After functionalization, the thermoplastic properties of the lignin were enhanced as shown by DSC. The novel thermoplastic lignin samples were applied with a bar coater forming an even coating on the paperboard substrate. The WVTR of the paperboard (840 g/m2 × 24 h) could be reduced to 260 g/m2 × 24 h with a TOFA lignin ester double coating of 3.9 g/m2. Furthermore, a decrease in OTR value was observed for the TOFA lignin ester as well as the TOFA coated paperboard samples. In contrast to the TOFA coating, the modified lignin coatings exhibited a high and stable contact angle (80° for 2 min). The coating material did not affect the tensile strength of the paperboard. According to the results, the demonstration of the conversion of lignin into a value added product has been shown. Furthermore, the novel coating material shows promising properties for the development as sustainable barrier material in fibre-based packaging material to replace oil-based barriers.
- barrier properties