RESEARCH ON SYNTHESIS OF EPOXY IN MICROEMULSIONS SYSTEM TO APPLY IN WATER-BASED PAINT FOR METAL

Abstract

In this study, bisphenol A epoxy resin (EEW = 938 g/eq) was reacted with excess ethylene diamine to bind two amino groups at both ends of the circuit to form epoxy amin-adduct (called adduct). Residual amine is separated from the reaction mixture to obtain an isolated adduct. After that, the amino groups (bases characteristic) at the ends of the adduct circuit will be neutralized with acetic acid to form adduct salts soluble in water. The structure of adduct salt with two hydrophilic polar ends, in the middle is an oil-like epoxy molecular circuit similar to that of a surfactant. Therefore, adduct salt acts as an emulsifier for the dispersion of another bisphenol A epoxy resin (liquid form, EEW = 187 g/eq) into the water. The result is a highly dispersed emulsion system with an emulsion size of about 0.0693-0.1000 µm (called epoxy microemulsion system). When this system is painted on metal and cured surfaces at 170 °C, adduct salt under the effect of temperature will release amine group as curing agent for liquid epoxy resin. The post-curing coating film has 100% adhesion, 6H hardness, 2 kg.m impact resistance and at 3 mm bending diameter no cracks appear on the sample surface.

Keywords: Bisphenol A epoxy resin, water paint, emulsion system, epoxy microemulsion.