Extraction of lignin from Eucalyptus and Casuarina wood chips and coating on paperboard for sustainable food packaging applications

The increasing demand for sustainable and biodegradable food packaging materials has encouraged the use of lignin-based coatings. In this work, lignin was extracted from Eucalyptus and Casuarina wood chips (in the ratio of 1:1) as a byproduct of the kraft pulping process and applied as a coating material. To improve its performance, lignin was blended with acrylic latex, a binder for pigment. The coating was applied on 160 gsm paperboard using a laboratory bar coater and dried in a hot-air oven at 105°C. The coated paperboard was tested for its physical and mechanical properties. To understand the effect of Lignin, sheets coated with acrylic latex also studied. The resulting paper had a GSM of 160.9 and a coat weight of 0.71 g/m². The tensile strength and stiffness (GM) were measured as 11667 N/m and 41 mN respectively. Cobb60 value is 20.1 g/m², the burst strength reached 560.1 kPa also exhibited an opacity of 99.99%. In addition, shade and colour difference were also analysed. Overall, the results indicate that lignin can be effectively utilized as a bio-based coating material, providing an eco-friendly material that has prominent light stopping and UV absorbing ability than conventional polymer coatings for sustainable packaging applications.