Search Results

Conventional prepainted organic coatings on zinc nickel substrates consist of a dried-in-place chrome bearing pretreatment layer followed by a thin film solvent-based organic topcoat. This system is generally applied in order to provide additional corrosion protection to the brittle zinc nickel layer subsequent to forming. An improved version of this organic/metallic coating system has been developed which consists of applying a one-coat water-based chrome bearing epoxy to zinc nickel material. In addition to the production efficiencies gained by applying a one-coat prepainted system, enhancements are also realized with regard to corrosion resistance and formability characteristics. It has also been found that a novel curing technique can be utilized in order to allow for higher temperature curing of prepainted materials on bake hardenable substrates without adversely affecting mechanical properties.

Selection of a coating system for prepainted metal, whether “preprinted” or “prefinished” requires consideration of the conditions under which it will be used. Factors to be considered are: type of substrate to be painted, joining method, forming requirements, service environment, and need for repaintability. Because of the great variety of coating systems available, it is possible to tailor prepainted systems to meet the same requirements as do many postpainted parts. However, it is necessary to insure that the coaters and their coating vendors understand accurately what the systems are required to do. This paper will outline the physical and chemical characteristics of some of the coating systems available from the coil coating industry today, and describe their performance with respect to the factors mentioned above.