Coopbox Group showed to the last Emballage in Paris Natural box, a tray for foods, thermoformed and made by biodegradable plastic material. This packaging is the result of an intensive research project started in October of 2000 whose aim was the marketing of containers strong enough to bear the mechanical stress during the packaging phase and able to keep their form and their mechanical characteristics also in presence of liquids, as one can already discover in packaging of many foods.
The first stage of the project was the choice of raw material, fallen on PLA, a bio-polyester material composed by lactic acid monomers. After choosing the material, the productive process has been set up. The whole extrusion line with its operating parts was fitted to the characteristics of this material, considering the difficulty to keep in solution the atmospheric gases chosen as expanding substances. The modifications concerned the screws of the primary and secondary extrusion system and its head.
The tray for meat packaging is still under implementation. We are working hard to estimate the performances of packaging made completely of PLA and composed by an expanded and laminated PLA box with a PLA lid. The examined performances concern the transmission speed of gas and steam and the evaluation of the draining capacity. Concerning this one, the expanded PLA obtained by the process proved to have a high draining capacity and a poor liquids retention inside the material. The liquid dispersion speed towards the outside proved to be perfectly in balance with the absorption speed. In this way liquids are not retained by packaging, but they are released outside so slowly that they keep dry the desks where they are placed. These results together with specific shelf life tests will allow to improve new packaging typologies.