ABSTRACT
The surfaces of solids generally adsorb CO2, O2, N2, and H2O from the atmosphere and are frequently covered with molecular films of fats and oils. When such a metal is mechanically polished or cleaned with an organic solvent for degreasing purposes, wetting of the adhesive, or adhesion, can be improved. Although the contact angle between the metal surface and water just after cleaning is approximately 70 to 90°, showing lipophilic characteristics, an oxidized film is produced on it in an atmosphere that is hydrophilic in nature [1]. For instance, an oxide layer such as Fe2O3 and Fe3O4 is produced on the surface of iron. Such a layer spontaneously developes rust, which prevents adhesion because it is brittle and contaminated. The rusty surface of metal is therefore mechanically polished or pickled to form continuous, active, tough oxide film by further surface treatment. Recently, quantitative measurement of the adhesion properties of polymer films to metals has also progressed [2,3].
