Water-dispersion varnish for electrodeposition and process for making said water dispersion varnish

A process for preparing a water-dispersion varnish suitable for electrodeposition which comprises reacting

• The reaction product of
• A. a polyesterimide having a carboxyl group in its chain or at the terminus of the chain and having an ester group and an imide group in its repeating unit or a polyesteramideimide having a carboxyl group in its chain or at the terminus of the chain and having an ester group, an imide group and an amide group in its repeating unit and
• B. an organic compound having at least two hydroxyl groups with
• C. a polybasic acid or its anhydride in the presence or absence of a solvent yielding a modified polyesterimide or polyesteramideimide having a molecular weight of from 5,000-100,000 and an acid value of 10-100;
• dissolving said modified polyesterimide or polyesteramideimide in an organic solvent;
• dispersing said modified polyesterimide or polyesteramideimide solution in an aqueous solution containing a surfactant and a volatile base;
• and forming a water dispersion of said modified polyesterimide or polyester amideimide by passing or bubbling an inert gas through the dispersion of said modified polyesterimide or polyester amideimide solution and said aqueous solution to remove all or part of said solvent and volatile base.