Coating method

Abstract

The present invention provides a method for forming a coating film, comprising the steps of: (a) coating a metal panel with a cationic electrophoretic coating composition and heating the composition to form an electrophoretic coating, (b) applying to the electrophoretic coating an aqueous primer containing a polyurethane emulsion prepared by subjecting a carboxyl-containing urethane prepolymer to chain extension by water, (c) applying an intermediate coating composition to the primer surface, (d) baking the aqueous primer and the intermediate coating composition at the same time, and (e) applying a top coating composition to the cured coating and baking the composition.

Dependencies are inferred from the claim text.