Rigid Packaging Oxygen
Rigid Packaging Oxygen and Water Vapour Transmission rate 10 8 6 4 2 0 OTR (cm≥/m≤d) | WVTR (g/m≤d) Q. 1050 350 µm Q. 1051 350 µm Q. 1051 500 µm Q. 1052 350 µm Fig. 4: Comparison of oxygen and water vapour transmission rates for different Huhtamaki PLA based barrier films and water vapour transmission rates of the different Huhtamaki PLA barrier film qualities 1050, 1051, and 1052. With increasing film grade number, the thickness of the barrier layer is increased, which explains the strong decrease of the transmission rate values. Besides the thickness of the barrier layer, an increase of the overall film thickness also reduces the permeation values to a certain extent. However, this decrease is not as pronounced as the one related to the thickness of the barrier layer. As the thickness of the film applied is mostly determined by the application specification, the required barrier level of the PLA film is normally adjusted by choosing an appropriate barrier layer thickness, which is represented by the three different grades shown in figure 4. The ability of a Huhtamaki PLA barrier tray combined with a PLA barrier lid film to keep a modified gas atmosphere inside the packaging over a long period of time is presented in figure 5. The results show an excellent stability of the gas composition during the 32 days tested. 100 80 O 2 | CO 2 | N 2 N 2 CO 2 Up to now, there is no appropriate bio barrier material available in the market, which is either biodegradable or derived from renewable resources. To be able to offer a sustainable solution, the Huhtamaki BioWare range was extended by developing films that are mainly biobased. Actually, a conventional barrier material was used, which is not biodegradable. However, due to the PLA basis of the films, they have a very high content of materials with an origin of renewable resources and could be certified “OK biobased” by Vinçotte with up to three stars for a content of bio-based material between 60% and 80%. Of course, the selection of an appropriate bio barrier material is an ongoing research process for Huhtamaki Films. Composition of Gas in % 60 40 20 O 2 0 1 7 15 32 Time in d Fig. 5: Temporal stability of a modified gas atmosphere inside a packaging of a Huhtamaki PLA barrier tray and lid film All Huhtamaki PLA films for thermoforming can be easily processed on conventional production lines using standard machines, tools and moulds. This was confirmed by performing numerous trials with different machine manufacturers, converters and end users. Compared to common materials for thermoforming, they are processed at significantly lower temperatures, saving energy for the production and, therefore, giving an additional benefit to the environment. www.huhtamaki-films.com 20 bioplastics MAGAZINE [02/12] Vol. 7
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