METHOD FOR MANUFACTURING DOUBLE-LAYERED COATING FILM

To provide a method for manufacturing a double-layered coating film which has a smooth appearance even when the double layered coating film is subjected to wet-on-wet coating using an aqueous paint composition as an undercoat paint composition.SOLUTION: A method for manufacturing a double-layered coating film comprises, first, an undercoat coating film forming step for coating an object with an undercoat paint composition. Then, the undercoat coating film is coated with a topcoat paint composition in a wet-on-wet manner. After that, both coating films are simultaneously dried, forming the double-layered coating film. The undercoat paint composition is an aqueous paint composition containing an aqueous main agent (I) and an aqueous curing agent (II). The aqueous main agent (I) contains an aqueous dispersion of an epoxy resin (A). The aqueous curing agent (II) contains a polyamine compound (B), and an organic solvent (C). The polyamine compound (B) includes a polyamine compound (B1) having an active hydrogen equivalent of 100-200 g/eq inclusive and a polyamine compound (B2) having an active hydrogen equivalent of 300-900 g/eq inclusive.SELECTED DRAWING: None 【課題】下塗り塗料組成物として水性塗料組成物を用い、ウェットオンウェット塗装した場合においても、平滑な外観を有する複層塗膜の製造方法を提供する。【解決手段】被塗物上に、下塗り塗料組成物を塗装する下塗り塗装膜形成工程、前記下塗り塗装膜の上に、上塗り塗料組成物を、ウェットオンウェットで塗装した後、両塗膜を同時に乾燥させて、複層塗膜を形成する複層塗膜の製造方法であって、前記下塗り塗料組成物は、水性主剤（Ｉ）及び水性硬化剤（ＩＩ）を含む水性塗料組成物であり、前記水性主剤（Ｉ）は、エポキシ樹脂（Ａ）の水分散体を含み、前記水性硬化剤（ＩＩ）は、ポリアミン化合物（Ｂ）を含み、及び有機溶剤（Ｃ）を含み、前記ポリアミン化合物（Ｂ）は、活性水素当量が１００ｇ／ｅｑ以上２００ｇ／ｅｑ以下のポリアミン化合物（Ｂ１）及び活性水素当量が３００ｇ／ｅｑ以上９００ｇ／ｅｑ以下のポリアミン化合物（Ｂ２）を含む。【選択図】なし