Ascorbic acid ester in ambient temperature cure coatings

Ascorbic acid was reacted with t-butyl acetoacetate under relatively mild conditions to obtain a multifunctional β-ketoester. 1H-NMR spectroscopy and elemental analysis showed that the high-yield desired product was obtained and with a degree of substitution between 2 and 3. This β-ketoester was used to make a simple coatings mixture, which was, in turn, used to coat metal panels. Crosslinking was attempted using multifunctional amines, but this proved to be too rapid for any reasonable films to be made. Michael addition with multifunctional acrylates proved to be controllable by adjusting the catalyst level. The films obtained proved to have high levels of solvent resistance, high hardness, good gloss, and low impact strength. Gel content measurements and large increases in the glass transition temperature (T g) of the cured films indicated that high levels of crosslinking have been obtained.