Development of anti-corrosive paint with improved toughness using carboxyl terminated modified epoxy resin

•Modification of epoxy resin with Carboxyl terminated polyethylene glycol succinate (CTPS) to improve its toughness.•Epoxy modified with 5 wt.% CTPS (CPSE5) shows maximum elongation and highest adhesion strength among all the coating compositions.•CPSE5 coating gives long term corrosion protection among all coating compositions. Epoxy resins despite having excellent adhesion to various substrates, good corrosion and chemical resistance are less suitable for high-performance applications, as they are poor in ductility. In the present study, carboxyl terminated polyethylene glycol adipiate (CTPA) and carboxyl terminated polyethylene glycol succinate (CTPS) modifiers were synthesised and then used to modify bisphenol-A epoxy resin to raise the latter’s toughness. The study showed that in both the cases, 5 wt.% addition gave rise to the highest toughness as well as corrosion protection against salt fog and synthetic sea water exposure. However, between the two modifications the epoxy resin modified with 5 wt.% CTPS gave a better performance and so was pigmented with a mixture of zinc phosphate and red iron oxide to obtain the paint. The study showed that the epoxy resin modified with 5 wt.% CTPS + 30 vol.% pigments gave rise to the highest toughness (flexibility), adhesion and corrosion resistance when applied on to mild steel panels.