Preparation and cationic electrodeposition of amine—functional epoxy resins



2-Ethylhexanol-blocked toluene diisocyanate (2-EH-blocked TDI) modified resin was first prepared from epoxy resin and 2-EH partially blocked TDI and subsequently reacted with di(2-methylisobutylketiminoethyl)amine to obtain ketimine-terminated resins. These ketimine-terminated resins were hydrolyzed and partially neutralized with acetic acid to give macrocations. The resulting cationic resins were dissolved in suitable solvents and mixed with deionized water to form various emulsions. The formation of a stable emulsion is strongly dependent on the pH value of the emulsion and the amount of solvent added. Electrodeposition of the emulsion produced films of amine-terminated and 2-EH-blocked TDI modified epoxy resins on the surface of a cathode. Factors such as the pH value of the emulsion, the content of organic solvents, the amount of 2-EH-blocked TDI, applied voltage, and electrodeposition time on the electrodeposition properties (such as deposition yield and throwing power of the resins) were investigated. Moreover, the deposited film could be thermally cured to have a crosslinked structure. It was found that a temperature above 160°C is required to crosslink the deposited resins.