Functionalization of epoxy resin and the performance of the resultant magnesium-rich primer

Abstract

A magnesium (Mg)-rich primer can provide cathodic protection for an aluminum (Al) alloy due to the lower potential of Mg. However, the Mg-rich primer prepared by simple blends shows poor flexibility and impact resistance. In this paper, bisphenol-A type epoxy resin E-20 was graft modified by hydroxyl silicon oil (HS), amino silane coupling agent and diphenyl-methane-diisocyanate (MDI) by three different ways. Then Mg-rich primer was prepared by direct blends of modified resins. Results indicate that the introduction of siloxane groups could improve the comprehensive performance of the coating especially the flexibility and impact resistance. Furthermore, Mg-rich primer prepared from MDI modified epoxy resin even possesses excellent salt spray and aging resistance.