Life Cycle Environmental Impact Considerations in the Design of Novel Biobased Polyurethane Coatings

Substituting fossil-based with biobased chemical building blocks can potentially decrease the environmental impact of polyurethane (PU) coating production. This study applies life cycle assessment methods in the early development of three processes that incorporate biobased elements into PU coating production: a fully biobased coating made with organosolv lignin (OSL) and a biobased cross-linker from vanillic acid (VA) and two hybrid coatings made with a fossil-based cross-linker and either OSL or depolymerized OSL. Coatings with biobased elements had impacts of 1.5, 2.6, and 19.9 kg CO2eq/kgcoating for coatings made with OSL, depolymerized OSL, and the fully biobased coating, respectively. Emissions are mostly associated with the fossil-based cross-linker in hybrid coatings and with solvents and heat needed for the production of the biomass-derived cross-linker. While this study demonstrates that the use of biobased compounds in hybrid coatings can reduce the environmental impacts of PU coatings in comparison to fossil-based versions, additional development of biobased cross-linkers and research into end-of-life scenarios are needed to further reduce the environmental impacts of biobased PU coating production.