Abstract
Reserach on avoidance of hazardous chemical substances in baking enamel coating on aluminum alloy has been continued. In this paper, powder coating specimen is estimated by outdoor exposure test in Okinawa prefecture. Main results are as follows. (1) The powder coating on chromium VIor III chemical conversion and anodic oxidation has excellent weatherability. Consequently the powder coating would be able to apply as building exterior. (2) Some kind of powder coating on chromium-free chemical conversion would be expected weatherability. It depends on combination of chemical and coating. Therefore, it is considered that the selection of the chemical and strict control on the preparation process are important. (3) The coating blistering and gloss retention change of the specimen that has been exposed at 2 sites (Ikeijima and Yabuchijima) in Okinawa main island and Miyakojima are different. The outdoor exposure test in South Florida is provided in overseas estimation methods for aluminum alloy bulding materials such as AAMA and QUALICOAT. However, it is important to take surroundings and distance from coast etc. into consideration for estimaion of the coating deterioration.
