Special Biodegradable
Special Biodegradable caps Last year, in combination with the “Vitamore“ PLA bottle sold by the German drugstore chain “Ihr Platz“, the Swiss company Wiedmer AG from Näfels in the Canton of Glarus introduced the world‘s first biodegradable closure for beverage bottles. Wiedmer AG focuses on tooling and mould-making parts as well as the production of injection moulded parts. The BioCap ® is a 3.6 gram standard PCO-28 cap with tamper-evident ring. The material is a compostable Mater-Bi polymer from Novamont, Italy. The geometry of the cap and the elastic Mater-Bi material allow the production of a perfectly leak-proof bottle. With oxygen permeability very much in mind Wiedmer asked the Fraunhofer Institute for Process Engineering and Packaging IVV in Freising, Germany, to carry out permeation tests. All BioCaps exhibited an oxygen permeation rate of 0.035-0.039 (cm3/d bar) - a comparable HDPE cap showed 0.027 to 0.032 (cm3/d bar). The tests were performed in line with DIN Standard 53380, part 3. Initially Wiedmer manufactured the caps on a two-cavity prototype mould. They were totally satisfied with the results and the very good processability of the MaterBi material. Detlef Wellner, Marketing and Sales Director at Wiedmer would like to stress that Wiedmer is grateful to Novamont of their support in finding the right MaterBi recipe, the mould design (shrinkage behaviour) and the processing parameters. Wiedmer have now built a 16-cavity production mould, that is currently on test. Wiedmer manufactures the BioCaps on a Netstal injection moulding machine. “And the caps were not exclusively developed for the Vitamore bottle“ says Detlef Wellner, “anyone looking for a compostable closure for PLA bottles can have them.“ Wiedmer AG puts great emphasis on protecting the environment. One example of ongoing production process improvements is the successful reduction of the amount of waste thanks to the recycling of injection mouldings. In the manufacture of plastic closures the use of a hot runner system has reduced waste to practically zero. The consequence is that the energy required for manufacturing, and the emissions produced, have been considerably reduced. In addition, all injection moulding production takes place within a closed loop system, including heat recovery. This heat is then re-used for heating the entire company site. Environmental protection, which has been actively integrated into the optimisation of Wiedmer‘s operating procedures by their employees, offers potential for further cost reductions. www.wiedmer-plastic.com 18 bioplastics MAGAZINE [02/07] Vol. 2
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