Life Cycle Analysis of a Biobased Resin: A Case Study on Acetoacetylated Lignin Resin

Lignin is the second most abundant biopolymer found on earth. Lignin is produced as a by-product by wood and paper industries, and to a lesser extent by cellulosic biorefineries. The bulk of the lignin generated is burnt as a low value fuel. In order to commercialize cellulosic biorefineries and promote biobased economy, cellulosic fuel needs to be cost competitive and have lower environmental impacts compared to their conventional counterparts. One way of sustaining biorefinery economically and commercializing it is to valorize the by-product lignin into higher value specialty products. However, before an upgrading pathway for lignin is recommended, a full environmental assessment is needed.

One attractive route for upgrading lignin is functionalizing it for coating applications with different unique properties. The aromatic and aliphatic hydroxyl functional groups in lignin can be substituted with acetoacetate functionality to produce acetoacetylated lignin resin. This resin can then be crosslinked with amines, polyisocyanates, or melamine-formaldehyde resins to obtain thermosets. The advantage of this process is that the polyol used in synthesis acts as a reactive diluent while crosslinking, which makes the process waste free.

In our study, we investigate the environmental performance of this lignin-based resin. We use the Life Cycle Assessment (LCA) method to assess the environmental impacts of the lignin-based resin and show whether the production of this resin is more sustainable than similar conventional coatings. The insights provided by the results from this study can provide valuable inputs in broadening the concept of integrated biorefineries.