Corrosion protection properties of new UV curable waterborne urethane acrylic coatings

Abstract

Looking to the development of sustainable and low impact chemical technologies, water based paints offer significant advantage especially for in field applications, where the problem of solvent emission is really stringent. Some water based coatings are represented by alkyd and epoxy paints, capable of cross-linking either by auto-oxidation or with polyamines. Polyurethane aqueous dispersions are finding wide acceptance due to their better durability, adhesion and mechanical properties. The research presented here describes the design, application and characterisation of well defined model structures of waterborne UV curing coatings. The waterborne resins used in this work are segmented anionomeric polyurethanes functionalised with acrylic end groups: they were prepared from polytetramethylene glycol, isophorone diisocyanate, dimethylol propionic acid, and hydroxyethylacrylate. The preliminary results concerning the corrosion protection properties of the new UV curable waterborne coatings applied onto metallic substrates are very promising and were obtained by using electrochemical techniques. Water uptake is the critical process determining the corrosion performance. In particular the necessity to formulate the coating starting from higher molecular weight polytetramethylene glycol for good barrier properties is evident from the electrochemical impedance spectroscopy data.