COBAPACK · Development of a new recyclable long life co-injected high barrier packaging for food applications, with broad design possibilities and reduced manufacturing costs

Plastics used in packaging are seen everywhere in developed societies. Demand of long life rigid packing with high barrier properties grows up quickly (around 200.000 Tn are produced annually in Europe). Barrier packages are employed to preserve foodstuffs from environmental agents, so to control the package permeability to gases (O2,N2,CO2) is very important. Furthermore, mechanical and food thermal treatment resistance (pasteurization and retort processes) and food contact grade are also relevant requirements. Due to the nature of plastic materials, only one plastic can not achieve all the demanded requisites, so these packages are made of combining no less than three materials in five layers; a water barrier polymer (outer layers) cheap and with good mechanical properties (PP,HIPS), an oxygen barrier polymer with high cost (EVOH,PVDC,PA) and an adhesive to join both. They are manufactured by a two-step process: Coextrusion to produce a cast multilayer sheet and Thermoforming to process the sheet into shapes. This production technology has the following problems: Co-extrusion: a) Synthetic polymers (mainly EVOH) used as inner layer are very expensive and chemically incompatible with the other layers preventing post-used packages recycling. b) Scrap production reaches at least 10%. Thermoforming: a) High scrap production (up to 40%) due to trims, especially in oval and round forms, and processing problems b) Design limitations: neither complex forms nor uniform thickness, and no high depth of draw ratio are allowed. In order to solve the above problems COBAPACK approach will consist on: a)Using destructurized starch from rich protein plants(a by-product with low cost soluble in water), to replace the synthetic high barrier materials allowing the separation of the different multilayer materials thus recycling 100% the final package b)Using co-injection process, one-step process with minimum scrap losses, savings in energy comsumption and broad design flexibility