In-Situ Phosphatizing Coatings I: An Air-Dried Lacquer System

By Chaohua Wang, Yi-Yuan Chuang, Chhiu-Tsu Lin

The formulation of in-situ phosphatizing coatings (ISPCs) was successfully performed for lacquer systems using a commercial nitrocellulose lacquer and an optimum amount of in-situ phosphatizing reagents (ISPRs). The in-situ phosphatizing lacquer (ISPL) system is stable, and shows no change in surface appearance and drying speed as compared to the unmodified lacquer (UML).

The ISPLs are applied on pine, poplar, and red oak wood boards, and on cold-rolled steel, aluminum, and laminated brass panels. Immersion tests in a 3% NaCl solution showed a remarkable enhancement in paint disbonding resistance for the paint film of ISPL on wood and metals compared to that of the UML sample.

The paint film protective performance of ISPLs is further evidenced by the lattice pattern tape testings, and by the cathodic delamination and electrochemical impedance spectroscopy.