Abstract: A method includes a step of applying an aqueous 2-package type first colored paint to form an uncured first colored coating film; a step of applying an aqueous 1-package type second colored paint to form an uncured second colored coating film; a step of applying a solvent-based 2-package type clear paint to form an uncured clear coating film; and a step of heating the uncured first colored coating film, the uncured second colored coating film and the uncured clear coating film to 75 to 100° C. to simultaneously cure these films. The solvent-based 2-package type clear paint contains a hydroxyl group-containing acrylic resin and a polyisocyanate compound in a ratio of 1.5 to 2.0 equivalents of isocyanate groups in the polyisocyanate compound relative to 1 equivalent of hydroxyl groups in the hydroxyl group-containing acrylic resin.

Abstract: A method for forming a multilayer coating film, sequentially conducting step (1) of applying an aqueous 2-package type first colored paint on both a metal member and a plastic member of an automobile outer panel to form an uncured first colored coating film; step (2) of applying an aqueous 1-package type white paint on the uncured first colored coating film by step (1) to form an uncured white coating film; step (3) of applying an aqueous 1-package type interference color paint on the uncured white coating film by step (2) to form an uncured interference color coating film; step (4) of applying a solvent-based 2-package type clear paint on the uncured interference color coating film by step (3) to form an uncured clear coating film; and step (5) of heating these coating films by steps (1) to (4) at 75 to 100° C. to simultaneously cure them.

Abstract: A method includes a step of applying an aqueous 2-package type first colored paint to form an uncured first colored coating film; a step of applying an aqueous 1-package type second colored paint to form an uncured second colored coating film; a step of applying a solvent-based 2-package type clear paint to form an uncured clear coating film; and a step of heating the uncured first colored coating film, the uncured second colored coating film and the uncured clear coating film to 75 to 100° C. to simultaneously cure these films. The solvent-based 2-package type clear paint contains a hydroxyl group-containing acrylic resin and a polyisocyanate compound in a ratio of 1.5 to 2.0 equivalents of isocyanate groups in the polyisocyanate compound relative to 1 equivalent of hydroxyl groups in the hydroxyl group-containing acrylic resin.