C23C22/367

Method for forming multi-layered coating film
10697066 · 2020-06-30 · ·

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.

Method for coating metallic surfaces with an aqueous composition

The invention relates to a process for coating metallic surfaces with a composition containing at least one of a silane, silanol, siloxane or polysiloxane that is capable of condensation, water and optionally an organic solvent. The composition also contains compound containing Ti, Hf, Zr, Al or B; and at least one type of cation or an organic compound d) selected from monomers, oligomers, polymers, copolymers and block copolymers. The coating freshly applied with this composition is rinsed with a fluid and is not dried thoroughly before this rinsing step so that the compound capable of condensation does not condense substantially before the rinsing step.