Board and its production manner null for aluminum alloy paint of can top

摘要

PURPOSE:To develop the Al alloy sheet to be coated for a can lid excellent in coating film adhesion by subjecting an Al alloy sheet to AC electrolysis in an aq. alkaline soln. to form an oxide film on the surface. CONSTITUTION:When a lid for an aluminum can is produced, an Al alloy sheet as the base material is subjected to AC electrolysis at 4-50A/dm2 current density for the time for the total quantity of electricity to exceed 80C/dm2 in an alkaline soln. of sodium pyrophosphate, sodium carbonate, sodium hydroxide, potassium hydroxide, sodium phosphate, etc., kept at pH 10-12 to form an oxide film on the surface in 500-5000Angstrom thickness. A PVC-based coating is applied on the oxide film to use the material for the can lid. Consequently, a can lid material strongly attached to the coating and without the remaining of a coating film, called feathering, on both sides of the inner surface of the lid at the opening when the lid is opened is obtained.