Winpak Films, Inc., Senoia, GA, was awarded a patent for a seven-layer film that provides excellent oxygen- and water-barrier properties for food packaging applications. The film is claimed as durable and with good optical properties. It is proposed as a replacement for oxygen-barrier films that rely on the use of ethylene vinyl alcohol copolymer (EVOH) or nylon MXD6, which lose their barrier properties when exposed to water.
Package options include bags, pouches, and chubs. Applicable product markets include meat, cheese, milk, condiments, salad dressings and other oxygen-sensitive products.
At the core of the filing and the literal core of the 7-layer structure is a layered blend of polyamide and amorphous polyvinyl alcohol (PVOH). It is noted that a film made without PVOH in the critical fourth layer does not exhibit the required oxygen barrier properties to provide the proper shelf life. In total, five of the seven layers are proposed as polymer blends.
What is also notable about the patent filing compared to others we have assessed over the past 18 months is that it is as brief in length—only 5 pages long—as it is of illustrations, in this instance just two, which show cross-section, layer-by-layer structures.