INDUSTRIAL PRODUCTION OF FOOD PLASTIC PACKAGING AND THE USE OF IRRADIATION FOR MODIFYING SOME FILM PROPERTIES

摘要

The four main industrial processes needed to produce a plastic packaging structure are: cast extrusion, blown extrusion, injection moulding, and blown moulding. Since one polymer may not offer all the protection and marketing properties required for a specific food product, multilayer films can be produced. Each layer will be composed of a different polymer and additives to meet all the requirements. Ionizing radiation plays an important role in the packaging industry, especially in the heat shrinkable barrier film production process. In this process, irradiating the film structure is aimed mostly at the cross-linking of the polyolefin. Cross-linked polyolefin-based films can withstand higher stretching rates, be better stabilized, and will both have a high degree of shrinkage and higher shrinking forces. This leads to very thin structures with very well balanced cost-benefit ratios and better final packaging presentation. The use of ionizing radiation for cross-linking polymers is one of the most successful cases of irradiation used by the industry. Besides cross-linking, scission may also occur in the polymeric structure, and it may liberate toxic or unwanted substances that can be transferred to the food. Therefore, irradiated food packaging materials should be thoroughly assessed according to active legislation to guarantee that it will not harm the consumer's health either in the short or the long term.