Films | Flexibles | Bags
Films | Flexibles | Bags Deep-Freeze Bio Packaging Article contributed by Andreas Bergmeier, Director Development, Dettmer Verpackungen GmbH, Lohne, Germany and Dr. -Ing. Christian Bonten, Director Technology, FKuR Kunststoff GmbH, Willich, Germany Deep freezing is a method of preserving foodstuffs containing water. During deep freezing the storage temperature of the food is set significantly below freezing point (at least -18 °C), thus slowing down or even stopping the growth of micro-organisms. Chemical and physical processes in food are also slowed down or avoided completely. Biochemical, and most notably enzymatic, reactions are also slowed down [1]. Requirements of deep-freeze packaging plastics materials Deep-freeze packaging preserves frozen food from drying-up and protects it against outside influences: light, air (oxygen), moisture uptake, contamination and infection by micro-organisms, outside odours and tastes, as well as mechanical damage. It needs to exhibit barrier properties and mechanical properties, and also needs to be printable and weldable. ‘Freezer burn‘ ‘Freezer burn‘ is a form of dehydration usually caused by improper packaging. The surface moisture has evaporated, and the food may appear lighter in colour and ‘dried out‘. While the food is safe to eat, the quality is lower. It often has an ‘off-flavour‘. Whilst at home one can manage to package the goods to be frozen rather carefully, however the filling process under industrial conditions looks different: frozen goods - some with sharp edges - may fall from a belt weigher directly into an open bag, which will then be immediately closed. Bio-Flex – bioplastics for deep-freeze packaging. FKuR´s trade name Bio-Flex ® stands for copolyester blends based on PLA which – depending on the respective grade – are produced from a high amount of natural resources. Bio-Flex does not contain any starch or starch derivatives. The material’s mechanical properties at low temperatures are particularly crucial for an overall deep-freeze packaging performance. High impact strength and dart drop strength at 12 bioplastics MAGAZINE [06/09] Vol. 4
Films | Flexibles | Bags Tear Rresistance Modulus of Elasticity Puncture Resistance Elongation at Break Seal Strengh Tear strength — PE — Bio 1. generation — Bio 2. generation Fig. 1 Comparison of mechanical properties these temperatures are a must in order to achieve approval. Low glasstransition temperature as well as homogeneous material and distribution of synergetic additives are the keys to meeting these requirements. Dettmer Verpackungen (Delo) in Lohne, Germany, uses Bio-Flex F 2110 as a basis for a multilayer system for deep-freeze packaging. A packaging film has been developed for the market leader in deep frozen potato products that meets the many and various requirements. McCain´s philosophy behind this concept is coherent: ‘100 % Bio – inside and outside’. McCain´s Bio Harvest products derive from certified, ecologically controlled cultivation. To emphasize this, packaging made from renewable resources was needed - which also had to be biodegradable. The biodegradation, including the inks, has been tested and certified according to EN 13432. High quality printing with up to 10 colours is possible and the packaging carries the well-established seedling logo. But, what about the mechanical properties? Astonishing results were achieved when the biofilm was compared with polyethylene of the same thickness. Delo, as market leader in deep-freeze packaging, with 13 blown film units, is known for its highly demanding performance. Delo coextrudes up to seven layers and prints on 12 flexo print lines, five of which are equipped with 10 colour decks. The latest generation of biofilms from Delo´s director of development contains up to 70 % renewable resources, without any compromise. Fig. 1 shows clearly that by means of Bio-Flex a leap into new dimensions of mechanical properties of thin packaging films has been achieved. There is currently no technical obstacle to a broad market launch. Delo have even managed to offer solutions that have so far not been possible with PE. Excellent puncture resistance or rigidity previously only achievable in multilayer systems, open up completely new scopes for design. High quality raw materials and compounds such as Bio- Flex today allow for a broad variety off coextruded films as ‘customized products‘. [1] www.lebensmittellexikon.de www.fkur.com www.de-lo.de bioplastics MAGAZINE [06/09] Vol. 4 13
