Nihon Parkerizing Co., Ltd.

Nippon Steel & Sumikin Coated Sheet Corporation

Nippon Steel Sumitomo Metal Corporation

Hiroyuki Oyokawa

Hitoshi Kikuchi

Hiroshi Kanai

Nobuyuki Shimoda

Nobuki Shiragaki

Ichiro Oura

Tomokazu Sugitani

Satoru Yonetani

Hiromasa Nomura

Tomohiro Iko

Shigeki Yamamoto

Eisuke Kudo

An aqueous surface treatment composition for coated steel sheet securing sufficient working adhesion while causing the formation of a surface treatment layer imparting excellent overhang corrosion resistance even without containing chrome, that is, a surface treatment composition containing a specific organic silicon compound, hexafluorometallic acid, a urethane resin having specific cationic groups, a vanadium compound, and an aqueous medium and sufficiently securing working adhesion while imparting excellent overhang corrosion resistance by the urethane resin having cationic groups and a total amine value of specific values is provided.

Surface treatment composition for coated steel sheet, surface treated plated steel sheet and method of production of same, and coated plated steel sheet and method of production of same

The aluminum-zinc plated steel sheet according to the present invention includes a plated steel sheet and a covering film that covers the plated steel sheet. The covering film contains a basic compound of transition metal other than cobalt and chromium, and metallic cobalt, or metallic cobalt and a cobalt compound. An amount of the covering film per one side is within a range of 0.01 to 0.8 g/m. An amount in terms of mass of transition metal other than cobalt in the covering film per one side of the plated steel sheet is within a range of 4 to 400 mg/m. An amount in terms of mass of cobalt in the covering film per one side of the plated steel sheet is within a range of 0.1 to 20 mg/m.

Aluminum-zinc plated steel sheet and method for producing the same

A surface-coated aluminum and zinc plated steel sheet in accordance with the present invention includes: a plated steel sheet; a composite coating film formed by applying an aqueous surface treatment agent on the plated steel sheet and drying the aqueous surface treatment agent. The aqueous surface treatment agent contains a water dispersible resin (A), a cobalt compound (B), and water, and has a pH within a range of 7.5 to 10. The composite coating film contains the water dispersible resin (A) and the cobalt compound (B). A percentage by mass of the water dispersible resin (A) in the composite coating film is 90% or more. A mass of the composite coating film per one surface of the plated steel sheet falls within a range of 0.5 to 3.5 g/m.

Surface-coated aluminum and zinc plated steel sheet and method of preparing same

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Chiba, Japan

Hiroyuki Oyokawa