1)What are the advantages of epoxy paints over alkyd paints, apart from better corrosion resistance?
2)In what scenario is it advisable to move on from alkyd to epoxy coatings?
3)What are the challenges involved in such a move?
Alkyds
Alkyds are widely used of the synthetic resins used on a variety of steel surfaces where extra barrier protection was deemed necessary. Alkyds are essentially modified polyesters that are synthesized by the reaction of polyhydric alcohols with polybasic acids. These are filled with aluminum and used on a variety of steel surfaces where extra barrier protection is required. The aluminum pigments, tend to be drawn to the surface of the film under surface tension where they orient themselves laterally to the substrate. Wiping with a dry cloth sometimes releases the unbound aluminum flake from these films onto the cloth. Leafing efficiency of the stearic acid coated aluminum flakes is reduced by some low surface energy chemical species. This is achieved by stripping the coating from the pigments or by lowering the surface energy of the binder below that of the pigment.
Epoxy
The aluminum pigments present in epoxy systems do not leaf as they do in alkyds. The aluminum platelets are more randomly distributed throughout the coating thickness, and lie at all levels of the film, presumably well separated by resinous binder.
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