The exploration of Michael-addition reaction chemistry to create high performance, ambient cure thermoset coatings based on soybean oil

Using Michael addition crosslinking technology, thermoset coatings were prepared from acrylated epoxidized sucrose soyate (AESS) and amine crosslinkers. AESS was synthesized from sucrose soyate, which is the sucrose ester of soybean oil fatty acids and has an average of about 12 functionalities per molecule. Due to the high functionality of AESS and fast reactivity of the amine crosslinkers, the coatings can be cured at ambient temperature (21 °C) in a relatively short period of time yielding good coatings properties. When AESS was reacted with 4′4′-methylene bis(cyclohexylamine), the acrylate group conversion was determined by FTIR to be up to 90%. It was also found that the type of solvent used in the coatings formulation affected the film formation and thus the coatings properties. The addition of 1,6-hexanediol diacrylate diluent in the formulations resulted in softer and lower Tg coatings. Using a trifunctional amine such as diethylene triamine, coatings could be prepared without the addition of any catalyst. Overall, thermosets made from AESS Michael crosslinking technology provide a highly bio-based coating system with good hardness and chemical resistance.