Formation of zinc phosphate coating on metallic surface
OwnerTakashi Senzaki, Ryoichi Murakami +2inventors
InventorsTakashi Senzaki, Ryoichi Murakami, Kiyotada Yasuhara, Masashi Takahashi
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Abstract
An acidic aqueous zinc-containing coating solution containing about 0.4 to about 1 g/l of zinc, about 5 to about 40 g/l of phosphate, about 2 to about 5 g/l of chlorate, and about 0.01 to about 0.2 g/l of nitrite, and useful for forming on metal surfaces zinc phosphate coatings that exhibit excellent adhesion to a paint film and excellent corrosion resistance after painting when used as an undercoat for the cationic electrodeposition of a paint film, and a process for applying coating composition, including continuous spray or intermittent spray.
Claims37
An acidic aqueous coating solution for forming a zinc phosphate coating on a metal surface consisting essentially of about 0.4 to about 1 g/l of zinc, about 5 to about 40 g/l of phosphate, about 0.01 to about 0.2 g/l of nitrite and about 2 to about 5 g/l of chlorate.
An acidic aqueous composition for forming a zinc phosphate coating on a metal surface consisting essentially of about 0.5 to about 0.9 g/l of zinc ion, about 10 to about 20 g/l of phosphate ion, about 0.04 to about 0.15 g/l of nitrite ion, about 2.5 to about 4 g/l of chlorate ion, and about 0.2 to about 2 g/l of one or more ions selected from the group consisting of nickel, cobalt, calcium and manganese.
A process for forming a zinc phosphate coating on a metal surface comprising contacting the metal surface with an acidic aqueous coating composition comprising about 0.4 to about 1 g/l of zinc ion, about 5 to about 40 g/l of phosphate ion, about 0.01 to about 0.2 g/l of nitrite ion, and about 2 to about 5 g/l of chlorate ion.
A process for forming a zinc phosphate coating on a metal surface comprising subjecting the surface to at least one cycle of the following sequential steps:
- (A) spraying the metal surface for about 10 to about 30 seconds with an acidic aqueous coating composition comprising about 0.4 to about 1 g/l of zinc ion, about 5 to about 40 g/l of phosphate ion, about 0.01 to about 0.2 g/l of nitrite ion, and about 2 to about 5 g/l of chlorate ion;
- (B) suspending the spraying for about 5 to about 30 seconds;
- and then
- (C) spraying the metal surface with the coating composition so that the total time of spraying is longer than about 40 seconds.
Dependencies are inferred from the claim text.