vor 3 Jahren

Issue 06/2019

  • Text
  • Biodegradable
  • Barrier
  • Compostable
  • Materials
  • Renewable
  • Products
  • Plastics
  • Biobased
  • Packaging
  • Bioplastics
Highlights: Films / flexibles / bags K-Show Review Basics: Multilayer Packaging Cover Story: Modern laminates


Films/Flexibles/Bags Because of the breathability, fruit and vegetable bags made of ecovio ® by BASF (Ludwigshafen, Germany) help food to stay fresh for a longer time. This is the result of a study by the University of Natural Resources and Applied Life Sciences (BOKU), Vienna, Austria which measured the shelf life of different types of fruit and vegetables stored in bags made of PE and of ecovio. ecovio is a certified compostable plastic consisting of the biodegradable copolyester ecoflex ® (PBAT) and other biodegradable polymers made from renewable raw materials. Fruit and vegetable bags made of ecovio show better water vapor and oxygen transmission rates: This leads to an optimal humidity and oxygen concentration for different fruit and vegetables in a bag with the right volume. This in turn results in a longer shelf life: For example, tomatoes can be stored for up to four times longer in ecovio bags than in PE bags. In this way, intelligent packaging can reduce food waste. In addition, fruit and vegetable bags made from ecovio are not just carrier and storage bags: reused as organic waste bags, they can improve the collection and recovery of food waste. Clean, safe and easy: collecting more organic waste with compostable dual-use bags The separate collection of organic waste is the prerequisite for the recovery of nutrients and hence a closed nutrient cycle. A number of pilot projects, e.g. in Berlin and in the district of Bad Dürkheim, Germany, but also in India and China, have shown that consumers collect significantly more organic waste with compostable plastic bags when they have easy access to the bags. Consumers then also collect food waste they would not ordinarily collect, such as oily, liquid food residues. In addition, the number of noncompostable bags thrown in the organic waste bin drops significantly. Compostable dual-use bags made from ecovio enable larger amounts of kitchen waste to be collected for organic recovery in a clean, safe and easy way – and without sodden bags and unpleasant odors, since ecovio is tear and wet resistant. Under the conditions of an industrial composting plant, ecovio is fully biodegraded by microorganisms and their enzymes within a few weeks (as defined by EN 13432). The valuable compost can subsequently be used to increase the nutrient density in the soil, thus closing the nutrient cycle. MT Avoiding food waste through intelligent packaging of fruit and vegetables 18 bioplastics MAGAZINE [06/19] Vol. 14

Films/Flexibles/Bags Additives improve the property profile of bioplastics Bioplastics undergoing blown-film extrusion at the Fraunhofer Institute for Applied Polymer Research: an employee adjusts the air supply in order to stabilize a polylactic acid/Vinnex compound (photo: Wacker). I nnovative additives allow to significantly improve the properties and processability of many bioplastics enabling them to replace many traditional plastics. With the Vinnex ® product range, Wacker (Munich, Germany) provides a variety of versatile additives for biopolyester or blends of biopolyesters, organic and inorganic fillers, and starch. In the packaging field especially, bioplastics could make a significant contribution to greater sustainability. Whether as shopping bags, blister packs, thermoformed trays for chocolates, trays for fruit and vegetables or film – bioplastics now cover a broad range of products. With its Vinnex range, Wacker offers a product line that significantly improves the processing of bioplastics such as biopolyesters and starches. The additive system based on polyvinyl acetate makes it possible to combine various biopolyesters, thus selectively influencing the properties of the created polymer blend. This opens up a broad, customizable product range for biobased plastic blends. The biopolyesters that are currently readily available and can replace plastics produced using petrochemicals include polylactic acid (PLA) and polybutylene succinate (PBS). Key applications for Wacker’s additives include plastic packaging or combinations of plastics and paper such as cardboard box coatings or the moisture-barrier lining in paper cups. Optimized Film Manufacture The polyvinyl-acetate-based additive Vinnex 2526 enables, for example, PLA- based blown and cast films to be optimally processed. The additive improves the melt strength, and thereby also the bubble stability during extrusion. It also enables the process temperature to be reduced by about 10 °C. By minimizing the necking, i.e. the constriction of the melt film that is often observed in PLA and PBS, the improved melt strength results in optimum thickness distribution. The otherwise good printability of the PLA or PBS biopolyesters is also further increased by using Vinnex. Vinnex also makes it possible to combine different biopolyesters with one another or with starch, and prevents postcrystallization effects. Representative Blister Packs and Shrink Films The optimum presentation of food is extremely important to appeal to consumers and to stand out from the competition. The improved melt strength obtained using Vinnex 2526 enables manufacturers to produce thermoformed blister packs with an optimal thickness distribution and transparency. Extremely good water-vapor permeability combined with high transparency makes a film made from PLA and Vinnex an ideal shrink wrap, for example for fresh vegetables. Optimum Adhesion of PLA on Paper During processing, the low-molecular Vinnex 2523 and Vinnex 2522 grades increase the initial adhesion of the polymer melts of the PLA film to paper. In addition, Wacker’s additives optimize the heat-sealing properties, which generates a permanent and strong bond between the paper and PLA. The film turns these paper cups into a compostable end product that is sustainable despite its single use. Summary By using the polyvinyl-acetate-based additives from the Vinnex range, not only can biopolyesters and other additives be better combined, their processing and property profile can also be optimally adjusted. The high-performance blends can also be processed on conventional machines. Another benefit is that Vinnex enables the various biopolyesters to be combined with each other and with starch, which substantially increases the range of applications and processing options of biopolyesters. Consequently, Wacker’s additives contribute to opening up new markets for bioplastics. MT Key applications for Wacker’s additives include plastic packaging or plastic films for food. Extremely good water-vapor permeability combined with high transparency makes a film made from PLA and Vinnex an ideal packaging film, for example for fresh vegetables (photo: Wacker). bioplastics MAGAZINE [06/19] Vol. 14 19

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