Research of the migration of bisphenol compounds in the production process of three-piece metal cans

The migration of nine kinds of bisphenol compounds from respective inner coating of intermediate product to 3% (m/v) acetic acid and 10% (v/v) ethanol after internal surface coating, external surface coating, color printing, varnishing, supplementary coating and full spraying of cans according to the practical production process of three-piece metal cans was studied. It was found that bisphenol F diglycidyl ether and its derivatives were not detected in both two simulated solutions, whereas bisphenol A (2, 3-dihydroxypropyl) glycidyl ether and bisphenol A bis (2, 3-dihydroxypropyl) glycidyl ether were detected in both simulated solutions. Moreover, bisphenol A (3-chloro-2-hydroxypropyl) glycidyl ether and other derivatives were also detected in 10% ethanol system, and the contents of all these detected bisphenol compounds increased significantly after full spraying of cans. Meanwhile, the contents of these compounds also remarkably increased after supplementary coating and full spraying of cans in 3% acetic acid system. The results suggested the two processing points including supplementary coating and full spraying of cans had potential impacts on the safety of inner coatings, which were deemed as key control points.