Adhesion of spray primers to plasma polymer coatings

Abstract

AbstractThe adhesion failure of a primer on a plasma‐polymer‐deposited substrate surface could occur at the interface of the substrate/plasma polymer or at the interface of the plasma polymer/primer. We examined the adhesion of spray (solventborne or waterborne) primers on plasma polymer coated substrate with the substrate/plasma polymer systems in which the adhesion of the plasma polymer of trimethylsilane (TMS) to the substrate was good. Waterborne primers adhered well to quite hydrophobic plasma polymer surfaces, except the untreated surface of TMS. The plasma polymer of TMS appeared to contain a significant amount of oligomers, which were not in the three‐dimensional network of the plasma polymer coating and caused poor adhesion of primers. The plasma treatment of the deposited plasma polymer of TMS increased the adhesion characteristics of the primers dramatically. The oxygen‐plasma treatment, however, made the interface water sensitive and made the wet adhesion poor. The argon‐plasma treatment of the plasma polymer of TMS was found to be a viable process that yielded excellent adhesion of spray primers. The plasma polymer of TMS deposited by a closed system, without further plasma treatment, yielded an excellent foundation for the application of spray primers. Waterborne, nonchromated primers adhered exceedingly well and survived 8 h of boiling in water (with a scribed surface) and became virtually nonstrippable by conventional stripping agents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1443–1457, 2002