Tert-butyl acetate: Non-HAP solvent for high-solids epoxy formulations.

Xylene is the traditional diluent solvent for formulating epoxy/amine paints used in protective coatings and linings. Currently, it is under regulatory pressure because it is on the hazardous air pollutant (HAP) list and it is also a volatile organic compound (VOC). Ketones and acetate esters are powerful solvents, but their use is limited by their reaction with the amine curatives before paint application. Tert-butyl acetate (t-BAc) proposed as a VOC-exempt solvent, is a nonreactive, non-HAP solvent suitable for both the epoxy resin and amine curative sides of a two-component epoxy system. Molecular modeling predicts very low reactivity of the t-BAc ester functionality with amine nucleophiles as a result of steric hindrance. Long-term aging studies with amine curatives in t-BAc solutions confirm these theoretical results. Kinetics of the reaction of amines with t-BAc and its n-butyl acetate isomer support the view that steric hindrance plays a major role in amine solution stability. [ABSTRACT FROM AUTHOR]