Film Properties and Formulation Considerations for Corrosion Resistance

The mechanisms by which organic coatings protect metal surfaces from corrosion have received a significant amount of study in both academia and industry, with significant disagreement over which is of primary importance. Three of the most commonly highlighted film properties influencing corrosion resistance are barrier properties (water and O2 permeability), adhesion, and electrochemical impedance. Discrepancies between studies may arise for a number of reasons including differences in polymer chemistries, test methods, and conditions.

In order to develop a mechanistic model specific to a particular chemistry, a focused study of 21 styrenated acrylic resins in clear formulations was conducted in an effort to correlate film properties with corrosion resistance on flat, bare, cold rolled steel. The implications of formulation choices, e.g. pigment volume concentration (PVC) and extender particle size, were also investigated. The findings of these studies were then leveraged into development of a next generation, styrenated acrylic direct to metal (DTM) resin capable of being formulated at < 50g/L VOC.

Presented at the Eastern Coatings Show, May 15-17, 2017