Provided is a method for forming a multilayer coating film, the method being capable of forming a high-brightness white multilayer coating film which is excellent in terms of brilliant feeling, smoothness, and weather resistance and with which white stains are suppressed. In this method for forming a multilayer coating film to form a brilliant coating film, a white multilayer coating film is formed by: sequentially applying a first coloring paint (P1), a second aqueous coloring paint (P2), a third aqueous coloring paint (P3), and a clear coat paint (P4) on a cured electrodeposition coating film formed on a steel sheet; and forming a first colored coating film, a second colored coating film, a third colored coating film, and a clear coat coating film which each have a particular composition, brightness, film thickness, and the like.

Provided is a method for forming a multilayer coating film, the method being capable of forming a high-brightness white multilayer coating film which is excellent in terms of brilliant feeling, smoothness, and weather resistance and with which white stains are suppressed. In this method for forming a multilayer coating film to form a brilliant coating film, a white multilayer coating film is formed by: sequentially applying a first coloring paint (P1), a second aqueous coloring paint (P2), a third aqueous coloring paint (P3), and a clear coat paint (P4) on a cured electrodeposition coating film formed on a steel sheet; and forming a first colored coating film, a second colored coating film, a third colored coating film, and a clear coat coating film which each have a particular composition, brightness, film thickness, and the like.

The invention relates to a composition intended for coating polymer films, making it possible to improve the adhesion between the film and a final coating, and to confer good barrier properties on the coated film. The coating composition comprises at least one acrylic and/or methacrylic polymer which has a gel content of at least 50% by weight, relative to the total weight of acrylic and/or methacryclic polymer, at least one crosslinking agent and at least one polyester comprising sulphonyloxy groups, which is water-soluble or water-dispersible.