Preparation method for emulsifier, emulsifier, aqueous epoxy resin dispersion and formulation method

An aqueous epoxy resin dispersion, comprising an ionic active emulsifier prepared by reacting sulfamic acid and/or sulfamate as a first reaction raw material with an epoxy resin to obtain the ionic active emulsifier, wherein the molecule of the ionic active emulsifier comprises at least one epoxy group from the epoxy resin and at least one sulfonic acid or sulfonate group from the first reaction raw material, and at least one non-ionic active emulsifier, wherein the total content of sulfonic acid groups and sulfonate groups of the ionic active emulsifier is 1.46 wt % to 50 wt % of the total solid mass in the aqueous epoxy resin dispersion;

• wherein the non-ionic active emulsifier is prepared by a method consisting essentially of:
• mixing a polyether-anhydride reactant whose molecule comprises at least one carboxyl group with an epoxy resin whose molecule comprises at least two epoxy groups, and carrying out a ring-opening reaction using the carboxyl group(s) of the polyether-anhydride reactant and the epoxy groups of the epoxy resin to obtain the non-ionic active emulsifier, wherein the molar ratio of the total amount of epoxy groups of the epoxy resin to the total amount of carboxyl group(s) of the polyether-anhydride reactant is at least 1:1.