Coatings for underwater and wet surface application

Epoxy-resin based paints generally offer very good corrosion-protective properties and are widely used in harsh environments such as the sea. They are two-pack systems, the curing agent normally used being polyamines or polyamides. Such systems find extensive use on structures exposed to dry conditions. When substrates lie under water or are constantly exposed to the wet, the above system is impracticable due to poor adhesion. For these environments, the curing agent has to be modified, and in such circumstances ketimines have been found to work. Many amines and ketones are used to obtain ketimines. The ketimine in contact with water hydrolyses, releasing a free amine, which in turn reacts with the epoxy resin and so curing takes place in situ. Reports on a study of effective ketimines in various coating system