Performance of novel tinplate products: adhesion of polyester to new, REACH-compliant steel substrates

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Steel food and beverage cans are generally coated with a lacquer to provide improved food preservation and to fit with legislation. These "epoxy-type" lacquers, until recently mainly based on bisphenol A (BPA), applied to tinplate have been used very successfully for many years. However, due to recent (food) safety concerns about the use of BPA lacquers, legislation has been introduced in Europe banning its use in cans. Protact (Tata Steel's polymer-coated substrate) is seen as the perfect candidate to solve these issues. Large investment projects are being realised in Trostre (Wales) and IJmuiden (The Netherlands) to increase production volumes and develop this growing market. Furthermore, European legislation requires industry to step away from Cr(VI) during production processes. Current substrate for Protact is a chrome-coated steel (ECCS), produced via a Cr(VI) process. Although the final product is Cr(VI)-free, ECCS needs to be replaced to protect the workforce against exposure to Cr(VI). To ensure availability of the right substrate Tata Steel has developed an alternative substrate, called TCCT, itself an active subject of EngDoc research. However, all mechanistic studies on adhesion of Protact to substrate were done on ECCS, and relatively limited understanding of the factors influencing the adhesion on TCCT are clearly defined. Polyester laminates (like Tata Steel's Protact material) are uniquely suited to solve all current (BPA) and future food safety issues and with the new substrate will also comply to the REACH legislation. In IJmuiden, already a new TCCT cell has been installed in the production line, and investment in Trostre will be done in the near future. With these large new investments being realised, the understanding of the material performance is essential for Tata Steel to support the use of Protact in the market. The theme of this proposal is to understand the properties of Protact with respect to adhesion of the coating under severe conditions like food sterilisation and to determine requirements of the material to achieve sufficient product performance.