Effect of surface treatments of titanium dioxide pigments on the cure of polyester/triglycidyl isocyanurate powder coatings

Titanium dioxide pigments will typically have an inorganic surface coating based on a blend of alumina and silica and an organic treatment. Both the organic and inorganic treatments can influence the cure characteristics of polyester powder coatings. This paper attempts to explore the connectivity between the nature of the coating and the cure behavior of a typical heat-cured epoxidized isocyanurate formulation. It is found that a high silica:alumina content in the inorganic pacification layer significantly retards the cure process, but is influenced by the nature of the organic treatment. The organic surface treatment may accelerate or retard the initial cure process and gelation times. Elemental analysis indicates that some of the pigments studied have a significantly higher zirconium content and exhibited enhanced cure rates compared with those with the lower zirconium content. This paper illustrates the potential effects of different grades of titanium dioxide on the cure of polyester powder coatings.