PETpla.net Insider 06 / 2011

BOTTLE MAKING 14 PET planet insider Vol. 12 No. 06/11 www.petpla.net Better barriers for beer and beverages in PET bottles* The Institute of Plastics Processing at RWTH Aachen Uni- versity is investigating new barrier technologies that can cope with the drive towards lighter weight bottles, as well as the growing trend to biopolymers. Among the solutions being investigated and evaluated is the use of plasma- assisted barrier coating with bias substrates. The protection qualities and permeability of beverage packages are important criteria in choosing the right packaging material. Demands on packaging materials are not just about the goods being packed, they are greatly magnified by today’s trends and developments, such as the increasing use of biopolymers and light-weighting of bottles [1, 2]. In order to meet those challenges, the German Institute of Plastics Process- ing (IKV) at RWTH Aachen University has been working for more than 20 years on the field of plasma-assisted barrier coating of polymers. As well as the conception and development of processes for interior and exterior coating of beverage bottles or coating of foils and plastic components, inves- tigations have been focusing upon the development of suitable layer systems that will enhance the permeability and protection properties of plasma-poly- mer coatings. IKV is currently involved in a process that will enhance the barrier performance of plasma-polymer layers, through the use of a substrate-bias. Studies on foils have already shown that the deposition of barrier coatings using a substrate bias leads to a sig- nificant increase in its barrier proper- ties because the negative effect of layer defects is reduced [3]. A plasma reactor (fig. 1) that enables biasing of the inserted polyethylene terephthalate (PET) bottle has recently been built and studies on this new technology are currently being undertaken. After the process has been successfully validated, attention will turn to other materials, such as polylactide (PLA). The substrate bias’ influence on coating flexibility will be evaluated, as well as coatings performance. Any possible influence on strain tolerance is crucial for applications such as car- bonated soft drinks, as the stresses caused by the internal bottle pres- sure may lead to a stretching or even cracking of barrier coatings, which may result in higher gas permeation. Investigations will be undertaken in order to determine the extent to which deposition of multifunctional coatings, consisting of hard and soft layers, may increase the strain tolerance of the whole composite, while maintain- ing good barrier properties. Forschungsvereinigung Kunst- stoffverarbeitung (German Plastics Processing Research Association) research project 16306 N has been sponsored as part of the ‘indus- trielle Gemeinschaftsforschung und -entwicklung (Industrial Community Research and Development) by the Federal Ministry of Economics and Technology, pursuant to an enactment of the German federal Parliament through the AiF. www.ikv-aachen.de Fig. 1: Reactor for the substrate-biased interior plasma coating of plastic bottles *contributed by Ch. Hopmann, W. Michaeli, K. Bahroun, H. Behm, F. von Fragstein, Institute of Plastics Processing (IKV) at RWTH Aachen University, Germany References [1] P. Mapleston, Plastics Engineer- ing Europe , (2005), 15-19. [2] D. Ulutürk, M. Gernhuber, Verpa- ckungs-Rundschau , 61, (2010), 84-89. [3] A. Grüniger, A. Bieder, A. Son- nenfeld, P. R. Von Rohr, U. Müller, R. Hauert, Surface and Coatings Technology , 200, (2006), 4564-4571. BARRIER PET BOTTLES