Patent ID: 10697066

Abstract:
An object of the present invention is to provide a method for forming a multilayer coating film, the method capable of achieving excellent finished appearance and excellent corrosion resistance without affecting electrodeposition coatability even when a part or all of the water-washing step is omitted after chemical conversion treatment, and to provide a coated article. The invention provides a method for forming a multilayer coating film, comprising forming a chemical conversion coating film and an electrodeposition coating film on a metal substrate by Step 1 of immersing a metal substrate in a chemical conversion treatment solution to form a chemical conversion coating film, and Step 2 of omitting a part or all of the water-washing step, and performing electrodeposition coating on the metal substrate using a cationic electrodeposition coating composition to form an electrodeposition coating film, wherein the chemical conversion treatment solution contains less than 500 ppm of sodium ions on a mass basis, and hexafluorozirconic acid. The chemical conversion treatment solution preferably contains no less than 5 ppm to less than 50 ppm of sodium ions, no less than 5 ppm to less than 90 ppm of calcium ions, less than 100 ppm of potassium ions, and less than 90 ppm of magnesium ions, on a mass basis; and is used continuously.