Lignin Based Polyacids to Substitute Fossil-Based Materials in Coatings Formulations

Coatings provide protection against moisture, can improve fire resistance properties and simultaneously act as decoration. The aim of this work is to develop sustainable bio-based polyacids to substitute fossil-based materials in polyester and alkyd resin coatings. A sustainable process aims for reduced energy use, efficient resource use, minimal waste production and utilization of renewable and non-toxic products. However, very few commercial options and technologies for biobased materials are currently available.

Lignin, a renewable side stream from pulp mills and biorefineries, is currently underutilized. However, it has a high potential to provide not only higher economic returns, but also environmental benefits by substituting fossil-based coating formulations. The LigniOx technology, where lignin is oxidized by O2 under alkaline conditions, produces water-soluble polymeric lignin by increasing its anionic charge. These oxidized lignins have successfully been applied as concrete plasticizers and versatile dispersants. Currently, the LigniOx process conditions were adjusted to produce lignin based polyacids at high yield. The target is to obtain low molecular fractions of lignin polyacids for alkyd coatings. The high molar mass fraction is utilized as dispersants for coating formulations.

The development of sustainable alternative for synthetic polyacids for coatings using the LigniOx process also supports the feasibility and commercialization of other end-use applications developed and tested for the LigniOx lignins as well as aids in reaching the European target of carbon neutrality.