| 摘要 |
PROBLEM TO BE SOLVED: To provide a chromium-free surface treated steel sheet excellent in corrosion resistance in a flat plate or after processing, even if subjected to alkaline decreasing by a user or exposed in a corrosive environment for long periods of time, and also excellent in adhesive joinability. SOLUTION: On the surface of a galvanized steel sheet or an aluminum plated steel sheet, a surface treatment film is formed from a surface treatment composition obtained by compositely adding an organic phosphoric acid compound and an inorganic phosphoric acid compound at a prescribed ratio to a titanium-based aqueous liquid obtained by mixing a specified titanium compound with a hydrogen peroxide solution, and further, on an upper layer of the surface treatment film, an upper layer film is formed from a coating material composition obtained by blending a non-chromium based rust preventive additive and a solid lubricant containing a crystalline layered double hydroxide represented as [M<SP POS="POST">2+</SP><SB POS="POST">1-x</SB>M<SP POS="POST">3+</SP><SB POS="POST">x</SB>(OH)<SB POS="POST">2</SB>][A<SP POS="POST">n-</SP>]<SB POS="POST">x/n</SB>-zH<SB POS="POST">2</SB>O into a solvent based organic resin. By the combined action between the specific surface treatment film as a lower layer film and the upper layer film obtained by blending the rust preventive additive and the specific solid lubricant to the solvent based organic resin, particularly excellent corrosion resistance both in a flat plate and after processing and adhesion joinability can be achieved. COPYRIGHT: (C)2012,JPO&INPIT |
