Effect of baked temperature on the coating film formability of pre-coated aluminum sheets under drawing

Pre-coated aluminum sheets with surface functions are used in various fields. To prevent from peeling off of the coating film by forming, formability of the coating film is important. This study was investigated to develop pre-coated aluminum sheet that can be transformed by drawing forming. Polyester film with glass transition temperature of 273 K had the best formability in our experiments. When the baked temperatures were above 523 K or below 423 K, coating film had good formability. When the baked temperatures were between 443 K and 503 K, peeling off of the coating film were observed. Below 423 K, the cross-linking between the resinous molecules were not sufficient, the coating film had high elongation enough to transform largely. Above 523 K, the strong adhesion of coating film enhanced formability. For the coating film of pre-coated aluminum sheet transformed by hard condition forming, it is important to increase the elongation and adhesion of the coating film.