Basics Design for
Basics Design for recyclability By Michael Thielen Plastic recycling not only plays a vital role in increasing resource efficiency, it is essential for the transition to a circular economy. While reduce and reuse obviously take priority over recycling in the waste hierarchy, recycling is the next preferred option to be pursued. Ideally, plastics should be mechanically recycled as often as is feasible prior to their “final” recycling in the form of incineration (waste-to-energy recycling) or – where possible – composting or anaerobic digestion (biological recycling). Mechanical recycling refers to the various mechanical processes – including grinding or milling and subsequent melting – used to recover waste plastics and ultimately to produce regranulate from which new products can be injection moulded, extruded, thermoformed, blow moulded or otherwise produced. However, it is fair to say that the recyclability of any product is to a very large extent dictated by the way the product is designed. Design decisions, such as materials selection, the methods of assembly, labeling techniques, decorating techniques, and the like, all have a very significant influence on the ability to recycle a product or its constituent materials [1]. All plastic products Regardless of whether a plastic product is made from conventional plastics or from biobased and/or biodegradable plastics, there are a number of factors to be considered with regard to recyclability. Standard material identification: A variety of different material marking systems are used to identify the material from which a plastic item or component is manufactured. [1] Thermoplastics are the materials of choice, since only this group of plastics can be mechanically recycled without significant changes occurring in the properties of the materials. However, depending on the specific type of thermoplastic, the properties of these plastics can also undergo changes, both major and minor, over successive recycling loops (changes in molecular weight distribution, chemical structure, color, additive effectiveness, etc.). [1] Minimize the number of components and minimize the variety of used materials: Use snap fits (e.g. for CD jewel cases) and living hinges (e.g. for shower gel caps). If a second material is needed, for example for multi-shot mouldings, try to choose two materials that can be recycled together (e.g. PC, PBT and ABS) or that all can be biodegraded (such as PLA and PBAT). [1] Avoid the use of colour pigments or use the smallest possible amount, as these will subsequently not be able to be removed from a compound. “The fewer pigments you use, the lighter the colour of the recyclate will be and thus the broader the range of potential future applications,” says Michael Scriba, general manager of recycling company mtm (Niedergebra, Germany), in the recent issue of K-Profi [2]. “If pigments must be used, use light colours,” he adds. He also noted that fillers, such as chalk, may not be beneficial for a recycling process, as they modify the density of a material and hinder a gravimetric separation of plastics [2]. Another important topic are labels. Paper labels and glues should be avoided. “Plastic/glue/paper combinations are difficult to separate,” says Scriba. “During the washing process, the paper absorbs water, the fibres clump together and lead to high temperature development in the extrusion process which can then lead to undesired odor and stains in the recyclate” [2]. Hence in-mould labeling, with plastic labels made from the same plastic as the labelled product itself, are to be preferred. Design for easy disassembly is recommended for multicomponent products, for example by means of snap fits or screws. Again: use recycling friendly labels and attachments. Avoid coatings and glues [1]. Biodegradable plastics All of the aspects mentioned above certainly also apply in respect of biodegradable plastics. Many biodegradable plastics can be mechanically recycled. The most important additional aspect is that all components (e. g. all layers of a multilayer laminate or coextruded product) must be biodegradable. Make sure that colour masterbatches (pigments and carrier) are biodegradable, as well. The same is true for labels and glues. Biobased plastics The above mentioned recommendations also hold true with regard to biobased plastics. After they have undergone as many as possible mechanical recycling cycles, the preferred end-of-life solution for these plastics is incineration [3]. In a well-managed waste-to-energy incineration plant, biobased plastics are a kind of a renewable energy source. And finally, exactly the same technical, logistical and economic conditions for mechanical recycling apply in the case of bioplastics as for conventional plastics. Basically, all bioplastics can be technically identified and separated from the waste stream. This means that the volume of a particular type of plastic in the waste plastics determines whether separation is economical or not. From the point of view of waste logistics, therefore, separability is not the issue – the bottleneck is the fact that the amounts of bioplastics are simply too small for recycling to offer an economically profitable option [3, 4]. [1] Bonten, C.: personal consultation, Feb 2016 [2] Regel, K.: “Verpackungen brauchen ein recyclingfreundliches Design”, K-Profi, 1-2/2016, pp20 [3] Endres, H.-J.: personal consultation, March 2016 [4] Bellusova, D., Endres H.-J.: Mechanisches Recycling und Stabilisierung von Biokunststoffen, VDI Technikforum „Einsatz und Verarbeitung von Biokunststoffen“, Berlin, 30.09. - 01.10.2015 44 bioplastics MAGAZINE [02/16] Vol. 11
Published in bioplastics MAGAZINE 10 YEARS AGO new series 10 years ago In March 2016, Dr. Harald Kaeb says: “I chaired and managed the association from 1999 to 2009, during a period of strong growth and fundamental changes. It turned into a multi-sectorial international business organisation, covering biodegegradable, compostable and non-biodegradable durable plastics and products. We started media work and advocacy, everything grew like sugarcane. It was very exciting.” News 2016 The industrial platform for bioplastics and biodegradable polymers, IBAW, has re-named itself to become “European Bioplastics”. The new name expresses the geographic focus of its work and the emphasis placed on the role of renewable raw materials in production of plastics with regard to sustainable development and innovation. The members of IBAW have decided with a very large majority on the new name and have developed new statutes to prepare the organisation for the future. Dr. Harald Kaeb Chairman of European Bioplastics IBAW industry association becomes European Bioplastics Since its foundation in 1993, the association has undergone dynamic development. Founded as an industrial working group to define compostability and biodegradability of plastics, IBAW developed into body representing the interests of the bioplastics and biodegradable polymers industry. The association comprises today companies from different sectors: agricultural feedstock companies, producers of polymer building blocks and plastics additives, plastics producers and converters, industrial end users, as well as service providers in the form of consulting, research and waste management companies. The number of member companies has increased from 35 to 56 within the past 18 months. As a multi-sector association, European Bioplastics represents all issues within the product life cycle – from the cradle to the grave or even back to the cradle. All types of applications are covered. The association will deal not only with biodegradable polymer products, that comply with the EN 13432 standard, but also with those that are nonbiodegradable but based on renewable raw materials. The mission of the association is to support and promote - the growth and use of renewable raw materials in products and applications - innovation leading to lower environmental impact of durable and non-durable plastic products - independent third party certification and product labelling based on the EN 13432 standard, if biodegradability and compostability are claimed - separate collection of organic waste including compostable products, and composting - the identification and evaluation of other eco-efficient end-of-life options European Bioplastics will support the market introduction of renewable and biodegradable polymer products. This includes establishment of proper framework conditions and the communication of reliable upto-date information. On June 19 the association will introduce itself in Brussels, in November it will organise a two-day conference at the same location. More information is to be found on its website. www.european-bioplastics.org 8 bioplastics [06/01] Vol. 1 bioplastics MAGAZINE [02/16] Vol. 11 45
