The role of metal food packaging has been proved crucial during the Covid-19 pandemic and the necessary lockdown worldwide. People had to procure packaged food and other products for quite a long time, so the metal containers proved to be extremely useful, since they offer a healthy way of storage and transport, ensure long life, as well as a high quality in the preservation of consumer’s food. In addition, metal packaging industry represents an ideal example of a circular economy, since metals can be constantly recycled more than once in a loop. One of the most commonly used metals for packaging is tinplate, contributing to “sustainable development, which meets the needs of the present, without compromising the ability of future generations to meet their own needs”.

Tinplate products are sustainable and environment-friendly since they can be recycled and reused infinitely without loss of any of its properties. After the manufacturing process, tinplate is usually coated internally and externally with suitable organic coatings (lacquers and varnishes): the internal coatings are in contact with the food, protect the metal against corrosion and possible metal contamination of food. On the other hand, the external coatings contribute to the protection of the metal from environmental and mechanical shocks, ensuring the aesthetic upgrade of the surface and the print quality of the surface.

So, it is very important to use suitable coatings and printing materials and practises that meet European and international standards (Directives and Regulation) in order to achieve better print quality and simultaneously to minimise the carbon footprint. Saving resources and energy, reducing wastages, etc. tinplate food packaging can offer further green advantages and promise a greener world for tomorrow.

Α.BPA-free coatings for metal food packaging: The aim of the first part of the present study was the assessment of physicochemical and mechanical properties of a BPA-free and a biological BPA-free lacquer in comparison with a conventional one, which are applied on the internal surface of tinplate food packaging containers. The used coatings must have suitable physicochemical characteristics and must be applied by the appropriate technique, meeting the requirements and high standards described by legislation about materials in contact with food. For this scope, the selected coated tinplate specimens were examined and characterized by various experimental methods, such as dry and wet adhesion tests after hydrothermal treatment in various solutions - simulators of food packaging and by microhardness measurements. Then they were observed using an optical microscope / stereoscope, and their microphotographs were analyzed with the image Pro program for quantitative expression of the results. The analysis of the surface of the specimens was carried out by the use of Scanning Electron Microscopy SEM / EDS and Elemental Mapping. The results showed that the biological and the BPA-free lacquers response well to all tests and proved to be excellent alternative coatings to conventional ones in order to replace them due to the BPA content. In addition, the experimental tests for the quality control of the coating materials must be carefully designed since the phenomenon of corrosion of metal packaging containers is dynamic and involves many different factors (condition of the metal surface, food composition and environment which the metal surface comes in contact with, contact time, temperature, etc.).

Β. Reducing materials - time - wastage and saving energy: The second part of the study includes the good practices of a Greek company, concerning (i) the use of a new type of a commercial printing plate, and (ii) the use of a suitable software in order to reduce materials, energy consumption and save costs, while high quality and sustainability is ensured. The above-mentioned printing plate offers all of the benefits of existing chem-free alternatives but “brings also robustness to a whole new level”. It is with less cost, the most durable chem-free plate available on the market and it boosts efficiency, both in plate throughput as well as in run length, with optimal press performance, zero water and up to 75% less waste compared to other similar products (such as other commercial plates). This type of printing plate also supports up to 240lpi and incorporates a suitable tech­nology, contributing to the product’s chemical and mechanical robustness. It can facilitate run lengths as long as 350,000 copies, or up to 30,000 when using UV inks. In the examined case, Lefkosisdirourgia Kavalas S.A. in Greece has decided to launch this new type of printing plates for the reasons mentioned above. In addition, these plates represent a step further in photopolymer technology. With this technology one can go further in terms of robustness and it does not require any pre-heat, while previously if a company wanted to improve resistance and robustness in the case of commercial thermal plates, it would need to bake them. This is an example of good practices derived from companies, which support sustainability and promise a greener world for tomorrow. On the other hand, the company uses a software, which produces Print Production Format (PPF) files in order to integrate the Pre-press, Press, and Post-Press and enables transferring data through a simple production process (Workflow). The examined metal packaging company decided to use this type of format in order to manage information related to administrative data, inks (such as separations and ink coverage), register marks, comments, and preview images, contributing to sustainability, since it enables reducing make-ready times and wastage.