Improved curing performances of epoxy resin by a structure-controllable self-emulsifying curing agent

Curing agent is one of the indispensable components in waterborne epoxy resin system. However, its applications are seriously limited by the inferior emulsifying performances. By introducing hydrophilic segment, the curing agent can well emulsify the epoxy resin latex and thus improves the mechanical strength of cured film. In the present work, a structure-controllable self-emulsifying epoxy curing agent containing polyether segments was synthesized and characterized by FTIR and 1H NMR spectra. Then, effect of synthesis conditions on the performances of curing agent was studied, including the reactant ratio, reaction temperature and time. To improve the heat stability of curing agent and dispersion ability of epoxy resin latex, 5 wt% of HAc (to -NH) was applied as a neutralization agent. From the size of curing agent and epoxy resin latex measured by dynamic light scattering (DLS), it is found that the polyether segment in the curing agent remarkably affects the self-emulsifying and emulsifying abilities. The curing kinetics of liquid epoxy resin (E-51) in the presence of curing agent was studied by differential scanning calorimetry (DSC), and the curing process of cured film was observed by light microscope. Compared with the commercial one, the curing agent exhibits better construction and mechanical properties, which indicates that it possesses great potentials in the application of architectural and industrial coatings.