Food packaging simulant failure mechanisms in next generation steel packaging

Andrew Allman,Arnoud De Vooys,Rachel Hayes,H Neil Mcmurray,Eifion Jewell

doi:10.1002/pts.2448

Abstract

Legislative pressures have led to the mature dominant chromium‐coated steel (ECCS) substrate and epoxy phenolic lacquer replacement in Europe. An investigation was carried out to examine the interaction between a steel surface engineered with a novel, developmental substrate coated using Cr (III)‐based electrolytes and the food stuff being canned. Samples of lacquered material were subjected to a typical retort process (121°C for 90 minutes) and examined using a variety of laboratory analytical techniques. The foodstuff being packaged has a significant impact on the substrate/lacquer adhesion with clear differences in failure mechanisms between foodstuffs. There is clear evidence of chemical species transfer through the next generation lacquer, and this can instigate corrosion at the surface where incomplete chromium coverage leads to exposed iron. In general, the novel developmental material exhibits lower adhesive properties and shows a greater sensitivity to the foodstuff, although this is largely attributed to the homogeneity of the coverage. The novel substrate proves to be a promising alternative to ECCS due to REACH legislation, but improvement is required to achieve equivalent performance.

Highlights

Metal packaging is an important means by which food can be cooked, distributed, stored, and consumed in modern society with a global market of around $110 Bn in 2017, set to increase in the 5 years.[1,2] It is robust, fully recyclable, achieves many years of shelf life, and has established products with whole supply chain integrity,[3] widely known for its economic effectiveness.[4]
The purpose of this study is to investigate the effects of the sterilisation process on both the substrate and the organic coating, attempting to understand the interaction between the two at the interface,[8] or where any failure may occur
Neither substrate has free Cr (III) or Cr (VI) present on the surface after electroplating, and chromium is present in the form of Cr metal, oxide, or hydroxide; the details of which are shown in Table 1. 294269M shows increased levels of chromium oxide and lower values of metallic chromium when compared with electrochromium‐coated steel (ECCS), while showing some evidence of iron at the surface

Summary

Introduction

Metal packaging is an important means by which food can be cooked, distributed, stored, and consumed in modern society with a global market of around $110 Bn in 2017, set to increase in the 5 years.[1,2] It is robust, fully recyclable, achieves many years of shelf life (reducing food waste for producer and consumer), and has established products with whole supply chain integrity,[3] widely known for its economic effectiveness.[4] The substrate is coated to protect the foodstuff contained from being damaged or spoiled; the coating prevents the corrosion of the substrate material that could be induced by the interaction with the contents.[5]. Steel packaging manufacture faces the dual challenges of removing chromium (VI)[6] from the substrate production process and Bisphenol‐A (BPA) from the protective lacquer. A transition is required from a trusted mature technology to a novel substrate/lacquer combination, and this has renewed significant research interest in their performance.

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Methods

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Discussion

Conclusion