(JP10330983-A)      An electrolytic foil with a Vickers hardness of 180-320 at 25 C and a Vickers hardness above 150 after 30 minutes of heat treatment at 220 C. Also claimed is a process for producing the above foil by: (a) applying direct current across an insoluble electrode of titanium or lead coated with an element belonging to the platinum group as an anode and a rotary cylindrical metallic cathode; a sulphuric acidic copper sulphate electrolytic solution filling the space between them; copper is deposited on the surface of the cathode while the rotary cylindrical metallic cathode is being rotated; and (b) peeling off copper from the surface of the cathode to continuously obtain electrolytic copper. The electrolytic solution contains additives of 0.1-1.0 g/l of an oxyethylenic surfactant, 50-250 mg/l of a chloride, 1-10 mg/l of a glue or gelatin and 1-10 mg/l of a nitrogen-containing organic compound.    USE -   Electrolytic copper foil used as an electrode collector for a secondary battery, for printed circuit.    ADVANTAGE -   A copper foil with a high hardness is obtained. The presence of chlorine in the copper foil inhibits primary recrystallisation of copper, accomplishing an excellent thermal stability of Vickers hardness.    (US6231742-B1)      An electrolytic foil with a Vickers hardness of 180-320 at 25 C and a Vickers hardness above 150 after 30 minutes of heat treatment at 220 C. Also claimed is a process for producing the above foil by: (a) applying direct current across an insoluble electrode of titanium or lead coated with an element belonging to the platinum group as an anode and a rotary cylindrical metallic cathode; a sulphuric acidic copper sulphate electrolytic solution filling the space between them; copper is deposited on the surface of the cathode while the rotary cylindrical metallic cathode is being rotated; and (b) peeling off copper from the surface of the cathode to continuously obtain electrolytic copper. The electrolytic solution contains additives of 0.1-1.0 g/l of an oxyethylenic surfactant, 50-250 mg/l of a chloride, 1-10 mg/l of a glue or gelatin and 1-10 mg/l of a nitrogen-containing organic compound.    USE -   Electrolytic copper foil used as an electrode collector for a secondary battery, for printed circuit.    ADVANTAGE -   A copper foil with a high hardness is obtained. The presence of chlorine in the copper foil inhibits primary recrystallisation of copper, accomplishing an excellent thermal stability of Vickers hardness.