Synthesis and properties of a nonionic water-based epoxy curing agent

Owing to the requirement for environmental protection, water-based coatings have become a significant trend in the development of coatings. The water-based epoxy curing agent has also become a hot research topic. In this study, a B-A-B epoxy compound with a long hydrophobic alkyl chain connected to the intermediate nitrogen atom was synthesized at both ends of a molecule using ethylene glycol diglycidyl ether and 3,4-dimethoxyaniline as raw materials. Subsequently, the epoxy compound was sealed with triethylenetetramine. A nonionic, water-based epoxy resin curing agent with amino groups at both ends of the molecule was prepared. The target product structure was confirmed by infrared spectroscopy (IR), Mass spectrum (MS), and Nuclear magnetic resonance hydrogen spectroscopy ( 1 H-NMR). Additionally, through three factors and three levels of orthogonal experimental design, the optimum experimental conditions were confirmed, the optimum yield was 82.83%. The thermogravimetric analysis (TGA) indicated that the monomer exhibited a significant weight loss in the temperature range of 320–450°C. The pencil hardness, flexibility, and impact resistance of the waterborne epoxy resin coating film prepared by the non-ionic water-based epoxy curing agent reached or exceeded those of similar products at China and foreign countries.