| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface-treated steel plate capable of forming a stable rust not only in a rural area but also in a coastal area in early stage, hardly causing the generation of flowing rust and elution of an environmental pollutant, good in adhesion of the coating film after processing, and excellent in processability and weather resistance. SOLUTION: This surface-treated steel plate has an iron phosphate coating film on the surface of a steel plate, and a polyvinyl butyral resin-coating film coating at least any one or more kinds of Mo-based, W-based and V-based inorganic compounds in the proportion of >=1 wt.% based on the resin solid component and having 10-50μm thickness as the upper layer thereof. Preferably, one or more kinds of the inorganic compounds included in the butyral resin- coating film are heteroply acid containing two ore more kinds of P, Mo. V, Si and W, or salts thereof, and more preferably the butyral resin coating film contains one ore more kinds selected from a Ni-based inorganic compound, a Cu-based inorganic compound, a phosphoric acid-based inorganic compound and a hardly soluble sulfuric acid salt. |
