Examination of the surface and interfacial properties of an epoxide-urethane resin for surface coatings

Electrodepositable paints are used in the auto industry to provide the majority of the protection against corrosion to mild steel car body shells. They are generally epoxy/blocked isocyanate resins systems which are applied by action of an electropotential between the car and an anode. Upon heating to 175°C the blocked isocyanate deblocks, and crosslinking occurs predominantly via the formation of urethane and urea linkages. The aim of the project was to gain a better understanding of the factors which may affect the adhesion of the electrocoat resin polymer to a steel surface, to investigate possible replacements for the tin catalyst currently used, and to develop a quantitative mechanical test for paint adhesion. This was achieved by employing various analytical techniques including Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and mechanical testing. [Continues.]