Physical aging of thermosetting powder coatings

The physical aging behaviour of several thermosetting powder coatings has been studied in order to compare the relative stabilities of alternatives to those based on triglycidyl isocyanurate (TGIC). The aging behaviour at ambient temperature is studied by differential scanning calorimetry and is analysed by the peak shift method in order to determine the kinetic parameters of the enthalpy relaxation process. Comparison between the various systems based on carboxyl functional polyester cured with bisphenol-A epoxy resins (hybrid systems), with triglycidylisocyanurate (TGIC) and β-hydroxyalkylamide shows that the aging rate, expressed as the enthalpy loss per decade of aging time, is smallest for those based on TGIC, and hence that the performance of the alternative systems requires improvement as regards their stability.