Novel, Water-Based High-Performance Primers That Can Replace Metal Pretreatments and Chromate-Containing Primers

In previous research it was demonstrated that simple rinses with organofunctional silanes can be used to protect metals against various forms of corrosion. Such treatments also improve paint adhesion. However, when unpainted, the silane filsm are too thin to provide long-term corrosion protection. In this paper it will be shown that much thicker, primer-like coatings can be obtained from silanes if the silanes are mixed with organic resins and small particles, preferably nanosize. Self-priming coatings of up to 20 µm in thickness have been obtained with outstanding adhesion and corrosion protection properties. The components of such “superprimer” systems are all water-based, and they do not contain chromates or other toxic ingredients. Thus, they are environmentally friendly. This paper describes several successful superprimers and presents their performance data.