Special There are
Special There are different technologies available in order to complete the packaging unit with a film. Most common technologies are based on flow pack top seal films. Additionally, specifically for the packaging of food, one of the most common technologies is the one based on cling films. Today, especially based on biopolymers, there are different technologies available, depending on the needs of the product to be packed and/or the packaging technology. Most commonly used on transparent punnets are transparent top seal films. Different combinations in terms of transparency may be used, meaning a transparent film on an opaque punnet or vice versa, or both the same. The first products are meant for food that does not need special MAP treatment. New developments are proving that amongst biopolymers there are some, which do offer differential barrier properties (WVTR, N 2 TR, O 2 TR, CO 2 TR) and that will open new applications for MAP packaging. Importantly, in order to obtain adequate sealing properties, the Tm of the sealing layer of the film does need to fit with the tray on which the film is sealed. New biopolymers which offer differential sealing properties seem to perfectly match such needs. Similar properties are given for flow pack films, in order to achieve both good sealing results and high speed processing. It is evident that for most of the applications good printing, COF, hot tack etc. are needed, whether they be top seal films or flow pack. For some years different development activities have been carried out in order to develop cling films based on compostable polymers. Some positive results have been claimed by the market, and it is expected that by next year some first producers will present their products. In this specific case the opportunity to use biopolymers will just enlarge the application range of PVC cling films, as there is already a certain trend (in some European countries) to replace it with PE or alternative polymers. But much of the success, on which the use of compostable packaging is based, is the need to find new solutions in terms of waste treatment, as food packaging means: • Highly food-contaminated plastic. • Difficult to recycle. • Low potential energy recovery content (due to the high contamination) in case of thermal recycling. The new opportunity given by compostable bioplastics has an added value for both retailers and consumers, as: • Retailers do not need any longer to separate the content from the packaging (when the product expires). • This means a space reduction in terms of waste collection (packaging and food may be collected and treated together). • Waste management and treatment of such products would save energy. • The consumer gets packaging, especially when he purchases organic produce, which is more coherent with the nature of the produce. Some European retailers are starting to adopt more and more such materials, as on the one hand consumers are starting to ask for them, on the other hand it is proven that recycling, meaning composting of packaging, when contaminated with food, offers a valuable way of recycling. It is not only the source of the biopolymers which defines their environmental contribution or impact, it is very often more the recycling system that stands behind them, which defines their impact. Conventional polymers, when clean and not contaminated (as in the case of industrial waste), do offer their highest potential (environmentally) if recycled. Biopolymers, when used as packaging, do offer their best profile when composted. 20 bioplastics MAGAZINE [03/07] Vol. 2
