Oxazolidone ring-containing epoxy resin

An oxazolidone ring-containing aqueous resin prepared by a process comprising the steps of:

• reacting an oxazolidone ring-containing epoxy resin (a) having a structure of the formula:
• wherein R3 represents a residue excluding epoxy groups of diepoxide, X represents a residue excluding isocyanate groups of polyurethane diisocyanate, and n represents an integer of 1 to 5;
• and wherein X has a structure of the formula:
• wherein R1 represents a residue excluding isocyanate groups of diisocyanate, R2 represents a residue excluding hydroxyl groups of diol, and m represents an integer of 2 to 10,
• with at least one first active hydrogen compound (b) selected from the group consisting of monoalcohol, diol, monocarboxylic acid, and dicarboxylic acid to partially open the ring of the epoxy groups present in the oxazolidone ring-containing epoxy resin (a);
• and
• allowing the resulting product to react with a second active hydrogen compound having an ionic group (c) to open the ring of the rest of the epoxy groups.