At last month’s Interpack fair in Germany, Netstal of Switzerland and two partners demonstrated a new approach to injection molding high-barrier rigid containers. It uses a multi-shot process instead of a simultaneous multilayer coinjection process (such as that practiced by Kortec). First a preformed aluminum foil (or barrier plastic film) is inserted into the injection cavity. Then a layer of plastic is injected over the foil or film on the outer side of the product. Next, a second layer of plastic is injected onto the inner side of the container to completely encapsulate the barrier layer. This approach (which can also be used for lidding) protects the barrier layer from damage from the outside, isolates the barrier from contact with the food contents, and allows for in-mold labeling (IML) and incorporation of regrind into the outer layer. If aluminum foil is used as the barrier, there will be no “retort shock,” or temporary weakening of the barrier due to water absorption during steam sterilization. Shelf life reportedly can be comparable to that of metal cans.
The Interpack demo used an all-electric Elion 500 press from Netstal (U.S. office in Devens, Mass.), a mold from Glaroform of Switzerland, and robotic automation for inserting and removal from Ilsemann Automation of Germany (U.S. office in Sharon Hills, Pa.).