Lead Free Cationic Electro-Deposition for Automobile Body in White

Organic tin compounds were examined as replacements for the hardening catalyst function of lead in order to produce a lead-free cationic E-coat. The mechanism of the decline in adhesion, at the interface between the anti-chip primer and the primer surfacer, when an organic tin compound migrated to the anti-chip primer layer, was determined. Monobutyl tin compounds were found to have the lowest mobility within the film of organic tin compounds capable of functioning as hardening catalysts. A lead-free E-coat, employing a monobutyl tin compound, demonstrated no decline in adhesion, and the performance of the film was equivalent to that of conventional E-coat.