| 摘要 |
PROBLEM TO BE SOLVED: To suppress film adhesion and corrosion resistance from being deteriorated due to the machining at can making stage in a steel sheet by forming a metallic chromium layer mainly consisting of an amorphous structure and a chromium-hydrated oxide layer successively on the surface of a steel sheet, and thereafter coating a thermoplastic resin layer thereon. SOLUTION: On the surface of a steel sheet, a metallic chromium layer mainly consisting of an amorphous structure and then a chromium-hydrated oxide layer are formed successively, and thereafter a thermoplastic resin layer is coated thereon to obtain the objective thermoplastic resin-coated steel sheet for can making. Preferably this metallic chromium layer is subjected to electrolytic treatment in a bath contg. trivalent chromium ions as a chromium source, formate ions as a complexing agent and KCl or the like as an electroconducting assistant according to necessity to be formed on the surface of the steel sheet by about 30 to 200 mg/m2 coating weight. Moreover, the coating weight of the chromium-hydrated oxide layer is preferably controlled to about 3 to 25 mg/m2 expressed in terms of Cr. As the thermoplastic resin layer, a polyester film having about 10 to 50μm film thickness is preferable. |
