Avaliação da influência do sistema de recravação da tampa e do verniz interno do corpo na migração de ferro em latas de duas peças para o acondicionamento de refrigerante

Abstract

Beverage cans DWI made from tinplate need an organic coating to avoid iron pick-up. It can change the taste of the beverage compromising the product quality. The 2-piece DWI can has the end made of 5182 H481 aluminum alloy. This work aims to evaluate the influence of two different lacquers and compounds on the iron pick-up from the steel DWI can after storage with a cola soft drink. Analyses of iron pick-up and measurements of electrochemical impedance, during the period of storage of the cans were carried out. The experiments were undertaken with the cans in the normal position (six months at 37°C) and inverted position (2 months at 37°C and 2 months at room temperature). Scanning Electron Microscope with Energy Dispersive Spectroscopy (SEM-EDS) and Stereoscopy Microscopy were used as complementary techniques for material characterization. The SEM results permit to identify the need of the internal lacquer applied over the tinplate base, due to the formation of areas of exposed iron provoked by the removal of the tin layer during the drawing process. The Electrochemical Impedance Spectroscopy (EIS) and Atomic Absorption Spectroscopy show the best lacquer/compound system to be used to store cola soft drinks were lacquer 2 and compound 2. After 30 days of storage, the samples were morphologically and chemically characterized via Stereoscopy Microscopy and Energy Dispersive Spectroscopy. The EDS results identified the presence of phosphorous, calcium and sulfur in the can end.