RECENT ADVANCES IN AQUEOUS 2-COMPONENT SYSTEMS FOR HEAVY-DUTY METAL PROTECTION

Although waterborne coatings have successfully replaced their solventb orne counterparts in a variety of areas, their use generally has been limited to applications with relatively modest performance requirement s. Recently, advances in technology have allowed for the design of wat erborne coatings with performance suitable for more demanding applicat ions. The emergence of two-component waterborne polyurethane coatings exemplifies this trend. These coatings can provide performance similar to that of solventborne 2-pack urethanes, but with much lower VOC. Th e chemistry of these coatings is discussed, in light of its relevance to some of the technical challenges, e.g., pot life and CO2-gassing in thick films, unique to these systems. The use of 2-pack waterborne ur ethane topcoats in combination with low VOC waterborne acrylic/epoxy p rimers and intermediate coats is also described. Such multiple coat sy stems offer the promise of long term corrosion protection in severe in dustrial and marine environments, coupled with very low VOC. (C) 1997 Elsevier Science S.A.