While grades of polyolefin combined with barrier materials such as polyamides and EVOH are usually employed on a blown film line for the production of food films, PET has long established itself as the “mass plastic” for cast films. This is explained by its good mechanical properties and above all by its outstanding transparency and high amenability to further processing techniques such as thermoforming.
The endeavors of many companies to efficiently recycle PET came to fruition some time back in the form of successful recovery processes. One obstacle, however, continues to be the approval of grades of so-called rPET (recycled PET) for repeat use in direct contact with foods. Already established are many processes for the production of multi-layer film composites in which rPET is employed as the middle layer. Thanks to ongoing improvements in machine technology, rPET can now be used in direct food contact. The British company Sharp Interpack in Aylesham, for example, operates a production line with a capacity of 1,500 kg/h on which it produces packaging films from post-consumer wastes. Thanks to the use of a V-type screen changer from Kreyenborg GmbH in Münster, Germany, which removes even the finest impurities, the manufacturer has obtained PIRA certification of its film for the food sector. The films produced from ground PET bottles on a Vacurema inline sheet line by the Austrian companies Erema GmbH, Ansfelden, and SML Maschinengesellschaft mbH, Lenzing, have also received a food approval. This approval was recently extended to rPET from Erema’s Vacurema recycling lines and now even applies to packages for deep-frozen ready-to-serve meals.
Biomaterials have been on the advance for some time now, but only recently in connection with food packages. As the world’s first film maker in the packaging sector, Alesco GmbH & Co. KG from Langerwehe has been including carbon-neutral film products made of PE and from renewable resources in its product range since the beginning of 2009. The company has since launched a biofilm printed with solvent-free waterborne inks and a compostable shopping bag made from renewable raw materials. And, in time for Drinktec 2009 – again a first – it presented a compostable shrink film made from renewable raw materials.
The driving force behind the expanding use of biomaterials is the desire for resource conservation and compostability. Although the concept of sustainability is closely associated with biomaterials, it still has to be settled in each case whether a biodegradable material or a material based on biological raw materials is in fact greener and more sustainable than a conventional plastic. Biomaterials’ frequently hailed carbon-neutrality only really holds, says RWE SE, Frankenthal, if the manufacturers include purchased emission certificates or the installation of wind farms in the calculation. A drawback of film packages made of biomaterials is their higher weight compared to conventional PE, a fact due to their up to 30% higher density. Furthermore, biomaterials call for a higher input of energy in production.
Growing environmental awareness and the discussion of the pros and cons of various categories of materials have at any rate accelerated innovation in packaging made of plastics. It goes without saying that the goal is a sensible and resource-conserving treatment of all raw materials.
Press Department K 2010