Metal-plastic hybrid materials with aluminum and/or alloys thereof as metal component

A method for preparing a metal-plastic hybrid material, said material comprising a substrate S1 having at least one metallic surface and at least one thermoplastic material applied onto said metallic surface of the substrate S1, the method comprising at least steps 1) and 2) and optionally step 3a) or 3b);

• 1) applying an aqueous acidic composition at least in portion onto the at least one metallic surface of the substrate S1 to form a film at least in portion on said surface,
• wherein the metallic surface is made at least partially of aluminum and/or of at least one kind of aluminum alloy, and
• wherein the acidic aqueous composition comprises, besides water, at least one water-soluble polymer having least one kind of functional groups selected from the group consisting of acid groups, hydroxyl groups, amino groups, and mixtures thereof as at least one constituent a1), at least one metal cation selected from the group consisting of titanium, zirconium and hafnium ions, and mixtures thereof, as at least one constituent a2), and free fluoride anions as at least one constituent a3), and
• and optionally drying or curing the film to form a dried or cured layer,
• 2) applying at least one thermoplastic polymeric material TM1 at least in portion onto the film or onto the dried or cured layer obtained after step 1),
• wherein the at least one thermoplastic polymeric material TM1 is applied i) in a form of a foil or is applied ii) by injection in a molten state onto the film or onto the dried or cured layer obtained after step 1) to form the metal-plastic hybrid material, and
• 3a) optionally injecting at least one thermoplastic polymeric material TM2, which is identical to or different from the thermoplastic material TM1 applied in step 2), and which is present in molten state, at least in portion onto the surface of the foil of the metal-plastic hybrid material obtained after step 2) and i), or
• 3b) optionally applying a further substrate S2 having at least one metallic surface, said surface being made at least partially of aluminum and/or at least one kind of aluminum alloy and having undergone the treatment of method step 1), onto the surface of the foil of the metal-plastic hybrid material obtained after step 2) and i) or vice versa.