DESIGNING ELECTRICAL AND ELECTRONICS EQUIPMENT FOR THE CIRCULAR ECONOMY BY USING RECYCLED PLASTICS

Transcription

1 DESIGNING ELECTRICAL AND ELECTRONICS EQUIPMENT FOR THE CIRCULAR ECONOMY BY USING RECYCLED PLASTICS Brian Riise, MBA Polymers Inc., San Ramon, CA Abstract In order to conserve resources and at the same time spur economic growth, the European Union is pushing to establish a Circular Economy. For global businesses, including manufacturers of electrical and electronics equipment (E&EE), some of the principles of the Circular Economy will likely be applied globally rather than just within the European Union. This paper describes how the recycling of plastics from shredded waste electrical and electronics equipment (WEEE) fits within the Circular Economy, and provides some guidance to manufacturers looking to incorporate these recycled plastics in new E&EE. Furthermore, we provide recommendations on the design of E&EE such that plastics may be recycled more easily in the future. Introduction The volume of plastic produced globally in 2014 was 311 million metric tons [1]. The distribution of plastics demand by segment in Europe from the same study is shown in Figure 1. Agriculture 3% Others* 23% Packaging 39% Electrical and Electronics 6% Automotive 9% Building and Construction 20% * Others includes consumer and household appliances, furniture, sporting goods, health and safety and others. Figure 1. Distribution of European plastics demand by segment in 2014 [1] Studies have shown that recycling is the preferred environmental option for plastics at the end-of-life [2,3], but the fraction of plastics recycled was only 29.7% in Europe in Plastics from packaging were the most recycled, with national recycling rates mostly in the range of 25-50%. This suggests that plastics from durable goods such as automobiles and electrical and electronics equipment (E&EE) were recycled at rates well below 30%. In the US, recycling rates of plastics tend to be even lower. The rate of plastic recycled from municipal solid waste (MSW) was only 9.5% in 2014 [4]. Recycling rates from durable goods in MSW was even lower, at 7.5%. Many of the plastics in durable goods such as E&EE are highly engineered to meet the long-term performance requirements of these products, so it would be beneficial if these plastics could be recycled at higher rates. Such products can often be used in less demanding applications that might still typically use virgin plastics, but in some cases these plastics can be used in durable goods in applications similar to their original use. Such products can be a key part of the Circular Economy [5,6]. The method of handling waste electrical and electronics equipment (WEEE) depends on the type of product and where the product is recycled. Some handling of WEEE is necessary in order to remove hazardous components such as cathode ray tubes or batteries. Some recyclers take the hand dismantling further and end up recovering large pieces of plastics that can be baled and sold to plastic recyclers [7]. Other recyclers shred the WEEE (after removal of hazardous components) and recover the metals using methods similar to those used by recyclers of automobiles. The remaining material after most of the metal is recovered, which we refer to as electronics shredder residue (ESR), may be further processed by plastic recyclers with automated sorting equipment. The latter method of recycling plastics from WEEE is most common in Europe, whereas both approaches are practiced in the US [7]. European Directives covering WEEE provide targets for recycling of these end-of-life products [8]. The recycling targets are based on the entire weight of these products. The targets can only be partially achieved through the recycling of metals, so some portion of the plastics must be recycled. Despite regulations such as the WEEE Directive [8] and the success of some recyclers of plastics from WEEE [9,10], the actual recycling rates of plastics in the EU may be quite small due to leakage of a large fraction of WEEE from the formal recycling sector [11]. The collected amount of WEEE in Europe of approximately 3.5 million metric tons per year is far less than the 8-10 million metric tons put on the market [11], suggesting that nearly 2/3 of European WEEE might not be collected and treated in formal WEEE schemes. SPE ANTEC Anaheim 2017 / 814

2 As the Circular Economy develops over the next few years, the actual portion of plastics from WEEE that are recycled and used in new E&EE will need to grow. In order to accomplish this, policies will need to be enacted to encourage recycling and the use of plastics recycled from WEEE in new E&EE [12]. Furthermore, participants in the Circular Economy including plastic recyclers, designers of E&EE and manufacturers of E&EE will need to work closely to ensure that plastics from WEEE remain in the Circular Economy for E&EE. While the formal steps to develop a Circular Economy seem to be starting in Europe, we expect the trend to spread globally. Due to the global nature of most E&EE manufacturers, standards and best practices developed in Europe in response to Circular Economy initiatives will likely expand to include E&EE manufactured for other countries. In the following, we first describe a successful approach for recycling plastics from WEEE as implemented for over a decade at our facility in Austria [9,10]. We then provide guidelines for designing plastic parts in E&EE using plastics recovered from WEEE. Finally, we provide guidelines for designing E&EE products such that the plastics may be successfully recycled in the future. flake products are carefully controlled to ensure consistency of the end products. a) b) c) d) Figure 2. Product flakes recovered from the separation of European ESR, including a) ABS, b) HIPS, c) PP and d) PC/ABS Product flakes such as those shown in Figure 2 are compounded using a twin screw extruder. This step includes the addition of additives (usually small amounts of antioxidant, colorant, impact modifier and/or others as required), vacuum de-volatilization and melt filtration (typically removing non-melt particles smaller than about microns). An example of the final ABS product after the compounding step is shown in Figure 3. Composition of European ESR Plastics from WEEE include acrylonitrile-butadienestyrene (ABS), high impact polystyrene (HIPS), polypropylene (PP), polyamides (PA), polycarbonate (PC), blends of PC with ABS (PC/ABS), flame retardants grades of ABS and HIPS (ABS-FR and HIPS-FR), mineral and glass filled grades of PP, polyvinyl chloride (PVC), polyoxymethylene (POM) and many others [10]. In a typical mixture of European ESR as fed to MBA Polymers facility in Austria, the target plastics (i.e. ABS, HIPS, PP, PC and PC/ABS) to be recovered as premium products account for approximately 60% of the feed. Other plastics account for an additional 30% of the mixture, with the remaining portion of the mixture including rubber, wood, wires/metal, foam, glass and fines (i.e. particles smaller than 3 mm). Recovery of Plastics from ESR MBA Polymers has considerable experience and technical know-how for processing streams of plastics from durable goods such as ESR. More information about the process has also been covered previously [9,10]. Figure 2 shows examples of plastic flakes of the four types of products recovered from ESR using the MBA Polymers separation processes. The compositions of these Figure 3. ABS pellets from European ESR after compounding flakes with small amounts of additives Plastic Products from ESR Our facility in Austria produces plastic pellets from the ABS, HIPS, PP and PC/ABS it recovers by processing European ESR. Each product lot (22 metric tons) is tested using ISO test methods to ensure that the properties meet customer requirements. The color of the plastic products from ESR is limited by the existing carbon black, TiO 2 and other pigments present in the plastics (see Figure 2). Therefore, the natural color of the plastic products is dark gray (see Figure 3). Other shades of gray or black are also available, with light black being a standard color due to high customer demand. SPE ANTEC Anaheim 2017 / 815

3 For customers requiring improved mechanical properties, particular colors or other properties, additives may be compounded into the flakes in the extrusion step. After these additions, the post-consumer recycle (PCR) content of the products is almost always in excess of 90%. Standard grades may only include trace amounts of newly introduced additives (e.g. antioxidants), though, so these may have PCR contents greater than 99%. It is important to note that products recovered from streams such as European ESR can in fact have very consistent properties. This consistency is made possible because European ESR is a mix including plastics recovered from a wide range of E&EE products. If such a consistent feed mixture is processed using well-controlled separation processes, and the separations are followed by blending of either flakes (before extrusion) or pellets (after extrusion), it is possible to achieve a high level of consistency in product properties. All of the products described above are RoHS [13] and REACH [14]-compliant, though they do contain trace amounts of legacy substances of concern (e.g. heavy metals and flame retardants) that were formerly used in E&EE. Testing of each lot confirms RoHS-compliance, and periodic testing for the substances of very high concern (SVHC) published by the European Chemicals Agency (ECHA) confirms that these substances [15] are not detectable or are only present at levels well below the limits. Plastic products from European ESR has been sold into office products, household items, automotive and E&EE. Applications in E&EE include parts for vacuum cleaners, washing machines, lighting, coffee makers and printers. Figure 4 shows a few examples of E&EE applications. Figure 4. Example products manufactured using plastics recovered from European ESR Approaches to Enable the Circular Economy for Plastics in E&EE Design for Using Recycled Plastics In order to better use recycled plastics from WEEE in new E&EE products, a number of recommendations should be considered. Previous papers presented by manufacturers of E&EE have included a number of considerations [16,17], but we would like to further expand on these from the perspective of a supplier of recycled plastics. Since the natural color of plastics from ESR is dark gray due to the mix of pigments in the plastics, it is best to use such plastics in parts ranging in color from medium gray to light black. Light gray or deep black colors require additional processing (e.g. by using commercially available color sorting equipment) and/or high pigment loadings. White or colored parts are virtually impossible to make in large quantities from WEEE plastics. Applications with some tolerance for color variation (e.g. interior parts) are also good options for recycled plastics, since close color matching can be an expensive step for recyclers due to small variations in the amounts of legacy pigments in their feed material. E&EE manufacturers should also recognize that recycled plastics may contain a small number of contaminants that in some instances can affect the appearance of molded parts. It is therefore helpful to avoid lighter colored parts (where defects may be seen more easily) and to design with textured or matte surfaces (since defects are easier to see on very glossy surfaces). Designers may also wish to consider co-injection molding with the recycled plastic inside an outer layer of virgin plastic. Designers of E&EE products desiring to use plastics from WEEE should also focus on targeting applications not requiring high levels of flame retardancy (e.g. UL 94 V0 ratings). Most of the plastics that are currently recycled and available in the market (ABS, HIPS, PP) are not flame retardant, and therefore cannot be used in new parts requiring high levels of flame. In addition, plastics such as PC/ABS (that may be recovered from WEEE) don t necessarily meet UL 94 V0 ratings because of the mix of flame retardants in the plastics and the presence of some grades not containing flame retardants. We also need to recognize that many of the flame retardant plastics produced 10 or 20 years ago contained brominated flame retardants that are no longer acceptable today either through regulations (e.g. RoHS) or though preferences for halogen-free products. Because of such challenges, plastic recyclers will need to work closely with additive suppliers and compounders in order to supply flame retardant plastics with post-consumer recycle content. SPE ANTEC Anaheim 2017 / 816

4 Part designers and processors using recycled plastics should also consider the properties and processability of recycled plastics when designing molds, selecting molding equipment and processing these materials. Part designers should ensure adequate venting to limit splay marks, for example, and should also avoid part designs with weak points such as weld-lines and sharp corners. Processors should follow the plastic recycler s processing guidelines for drying and melt temperature ranges. In some cases, such as when the recycled plastic is to be used in a new and complex part, mold designers, molders and suppliers of recycled plastics should work together to make sure that the mold design is appropriate and that there is a reasonable processing windows for the material. Design for Future Recycling of Plastics Designing E&EE products with future recycling in mind is also critical for the Circular Economy. In order to accomplish this, we first ask a number of questions: Is the plastic recyclable? How is the plastic likely to be recycled? Hand dismantling? From shredder residue? Is the plastic commonly used in E&EE products? If not, the available volume of the plastic may make it less attractive to target for recovery. Will the plastic, or how it is incorporated into the product, add challenges to the recycling of other plastics? Will contamination from other plastics, additives, paints, coatings and contaminants found in shredder residue hinder recycling of the plastic? Once these questions have been considered and the plastic type has been selected for a given part, there are a number of additional factors to consider. These considerations, many of which are laid out in a design guide published over a decade ago [18], include guidelines for material selection (discussed previously in this section), specific considerations when using recycled plastics (discussed in the previous section on Design for Using Recycled Plastics ), general part design concepts, fastening and joining methods, coatings and finishes, material identification, and plastic processing to avoid degradation. General part design concepts include designing for extended life and re-use (this ensures a tighter closed loop in the circular economy), designing for disassembly (for repair and for recycling by hand dismantling), ensuring adequate wall thickness for slightly reduced mechanical properties, and adding ribs, bosses and gussets for stiffness (while ensuring rounded corners to avoid stress concentrations found in sharp corners). Considerations related to fastening and joining methods include limiting the number of dissimilar materials joining parts, using magnetic metal (e.g. carbon steel) for metal fasteners to facilitate removal in the recycling process, ensuring that any metal fasteners are selected for rapid removal in hand dismantling processes, including snap-fits and integral (molded-in) hinges to eliminate the need for other materials, avoiding adhesives that harm recyclability, using ultrasonic welding to bond parts of the same plastic type, and designing such that fasteners are not damaged during disassembly and reassembly (e.g. during repair). Considerations related to coatings and finishes include avoiding coatings and paint if possible. If paints or coatings are required, the paint or coating selected should be reasonably compatible with the plastic. Marking of plastic parts with the plastic type and grade (as required for parts larger than 100 grams in IEEE , for example) [19] can be useful when recycling is done manually. It is important, however, to recognize that manual recycling is far from perfect since molders may change materials without changing the label, and since such sorting is subject to human error [20]. Processing to avoid degradation is also important for later recycling, since any plastics that have degraded during initial processing will have reduced properties when recycled at a later date. To avoid excessive degradation, molders should 1) use a properly sized molding machine to reduce residence time, 2) ensure that plastic is not processed above recommended melt temperatures, 3) reduce the plastic s exposure to long heating cycles, and 4) consider tooling which minimizes regrind (e.g. consider using heated runner systems instead of cold runner molds). When using hot runners, however, it is important to keep in mind that contaminants found in recycled plastics from complex streams such as ESR can potentially cause problems with hot runner systems and pin gates. Conclusions Plastics recovered from WEEE and further compounded into pellets by MBA Polymers are useful for a number of injection molding applications. These recycled plastics can be used in new E&EE when a number of factors are considered in the design and processing of these materials. Furthermore, designs of new E&EE that take recyclability into account should facilitate the Circular Economy for E&EE in the future. References 1. Plastics the Facts 2015: An analysis of European plastics production, demand and waste data, data from PlasticsEurope (the Association of Plastics Manufacturers in Europe) and EPRO (the European Association of Plastics Recycling and Recovery SPE ANTEC Anaheim 2017 / 817

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