Effect of Temperature and Type of Solutions on Lacquer Delamination of Food Can by Electrochemical Methods

Abstract

The aim of this research was to investigate the effect of temperature and type of solutions on delamination of lacquer and to develop analytical method for industry of lacquer delamination coated can. It would be rapid and more precision method by using technique called “ACET” or AC/DC/AC method which is widely used in many industries. This technique was used with anodic and cathodic charge determination by potentiostatic method. The first was done by examination of lacquered can by EIS (AC) and anodic polarization technique followed by cathodic delamination (DC) with heating at different temperatures. EIS and anodic polarization technique were used again. Samples used in this study were tinplate can coated with polyester/organosol, tinplate can coated with epoxy phenolic and tinplate can coated with organosol. Solutions used as electrolytes were 1% w/v sodium chloride, 1% w/v sodium chloride mixed with 1% w/v sodium metabisulfite and 1% w/v sodium chloride mixed with 1% w/v sodium hydroxide. Testing temperatures were room temperature, 40oC, 60oC and 80oC. EIS technique was studied by three electrode system. Cathodic delamination was done by applied –6 V (DC) for 10 minutes but anodic polarization was performed at +6V (DC) for 5 seconds. Anodic charges, cathodic charges and images from mobile phone were consistent with results from EIS technique. It was found that lacquer delamination of epoxy-phenolic resin started at room temperature while delamination of organosol occurred at 40oC but polyester/organosol delamination appeared at 80oC. Solution which mostly affects delamination is 1% w/v sodium chloride mixed with 1% w/v sodium hydroxide. The best lacquer coating which were least damage is polyester/organosol.