Preparation and Properties of a Non-Ionic Amphiphilic Self-Emulsifying Waterborne Epoxy Resin via Phase Inversion Method

This study synthesized a non-ionic amphiphilic self-emulsifying waterborne epoxy resin using toluene diisocyanate (TDI), polyethylene glycol monomethyl ether (mPEG), and epoxy resin E44 as raw materials via a two-step synthesis. The waterborne epoxy resin was emulsified using the phase inversion method, and the emulsification process was investigated. The prepared emulsion was cured using a commercially available aqueous curing agent, followed by mechanical properties testing of the cured products. Results from FTIR and 1 H NMR hydrogen spectrum analyses confirmed the successful grafting of hydrophilic polyether segments onto the epoxy resin without ring-opening of epoxy groups. The optimal synthesis temperatures for the two-step process were determined as 50°C (first step) and 65°C (second step), yielding transparent and pure products. During inversion emulsification, the stirring speed was 2500 rpm, and the water addition rate was 0.03 mL/s. Emulsion stability reached its highest grade when the molecular weight of mPEG was 1000, with the smallest particle size of 109.23 nm and the lowest polydispersity index of 0.201. The cured product exhibited tensile strength of 5.43 MPa and flexural strength of 29.49 MPa, demonstrating favorable mechanical strength and flexibility.