Synthesis, characterization and development of high performance siloxane-modified epoxy paints

Diglycidyl ether of bisphenol A (DGEBA) epoxy was modified with hydroxyl-terminated poly dimethyl siloxane (HPDMS), through ring opening addition polymerization reaction. The structural elucidation of the siloxane-modified epoxy resin (ESR) was carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. The physico-chemical characterization of the synthesized resin (ESR) was done by standard methods. DGEBA and ESR, were subjected to paint formulation with the help of TiO2, Fe2O3 and lemon chrome pigments. The formulated paint systems were cured at room temperature with polyamide (PA) used as curing agent. The DGEBA–PA and siloxane-modified epoxy–polyamide (ESR–PA) paints were applied on mild steel strips. The physico-mechanical and anticorrosive performance of the coated panels was evaluated by standard methods. Thermal analysis of DGEBA–PA, epoxy siloxane/PA systems was carried out by thermogravimetric analysis (TGA). The effect of siloxane incorporation and the role of PA as a curing agent on the coating properties of these paint systems was also investigated. The ESR–PA system was found to exhibit good thermal and corrosion resistance performance.