Dual curing agents for optimized flame-retardancy and physico-mechanical properties of cycloaliphatic epoxy coating

Higher durability with excellent insulation properties is to be considered an important factor for the formulation of intumescent fire-retardant coating (IFR) against the external environment. In this work, two structurally different hardeners such as cycloaliphatic amine and polyamido amine were used for curing hydrogenated bisphenol-A epoxy resin (DGEHBA) to develop intumescent fire-retardant (IFR) coating for exterior applications. Initially, a differential scanning calorimetry study was carried out to estimate the curing kinetics of DGEHBA resin and the hardeners. The IFR coating was prepared by mixing fire-retardant fillers such as ammonium polyphosphate, pentaerythritol and melamine along with TiO2 pigment in DGEHBA resin. The prepared DGEHBA coating was mixed with two different hardeners individually and their combinations in different weight ratios to make a series of epoxy IFR coatings. The impact of curing on the protection ability and integrity of these coatings was evaluated by analyzing their thermal, fire retardance and physico-mechanical virtues. Furthermore, the coatings were also studied for accelerated aging in humidity, weatherometer, seawater immersion and salt spray chamber to deduce the sustainability of the coatings. We have demonstrated enhancement in both, physico-mechanical and fire-retardant properties by using the above prepared coating compositions.