PURPOSE: To obtain the titled aqueous dispersion capable of improving performance by adding to an anionic electrodeposition coating material, by emulsifying a resin composition containing a specific maleinized oil, etc., and water-insoluble thermosetting crosslinking agent in a specific proportion in an aqueous medium and heating the resultant emulsion at a specific temperature.
CONSTITUTION: A resin composition containing (A) a maleinized polybutadiene resin having negative charge in water in an amount of 100pts.wt. based on solid and (B) a water-insoluble thermosetting crosslinking agent capable of self-crosslinking and/or crosslinking with the component (A) by condensation or addition reaction, preferably melamine resin in an amount of 10W250pts.wt. based on solid is emulsified in an aqueous medium, preferably water and the resultant emulsion is heated at a temperature above the crosslinking temperature of the component (B), preferably under ordinary pressure. The heated emulsion is then added to an anionic electrodeposition coating material to afford the aimed dispersion capable of matting and improving performance of electrodeposition films.