Achieving sustainability objectives has increased in importance for those in the coatings industry. This includes the use of biobased raw materials in the production of resins. The use of biobased materials in coatings is certainly not new; shellac is based on a resin secreted from the lac bug, and some of the first polyurethane chemistry practiced was based on castor oil, both of which are still in use. The key limitation with such natural products was often performance. As application performance demands increased, more “engineered” solutions were developed based upon materials that were typically derived from petrochemicals. Today, the industry is pursuing more sustainable raw material sources that don’t compromise performance as end customers’ demand for greener products increases.
The use of dicarboxylic acids in coating applications is common, especially in the production of polyester resins via condensation polymerization, including polyester polyols for polyurethane coating applications. Aliphatic polyester polyols are typically produced based on petrochemical-derived adipic acid, which is experiencing environmental pressure due to the potential for NOx emissions. Biobased adipic acid is not currently commercially available. However, there are alternative biobased diacids available, such as the nine carbon chain diacid, azelaic acid, which can offer end products with equivalent or improved performance with the added benefit of sustainability.