Multilayer evoh / hdpe packaging in processing and performance of recycled hdpe

Kuraray, EVAL Europe N.V. (EE) produces Ethylene Vinyl Alcohol copolymers (EVALTM), which are used in multilayer structures in a combination with a wide range of materials such as High Density Polyethylene (HDPE) to produce multilayer bottles to provide superior barrier properties to gases, flavours or bring functional barriers against external contaminants such as mineral oils (MOSH,MOAH). Bottles are typically made by CoExtrusion blow moulding (Co-EBM) technology and are used for beverage packaging such as dairy products and specialty milk and other packaging applications for sauces or dressings or for the packaging of medical products for which the Water Barrier of HDPE is of added value. The objective of the study was to investigate if multilayer EVOH/HDPE rigid packaging material, which is a percentage of the post-consumer recycling stream, can be effectively sorted with the HDPE stream and decontaminated back to food grade approved for use as Post-Consumer Recycled (PCR)-HDPE into food packaging applications. Multilayer rigid food packaging found in the postconsumer recycling stream has been represented in the design of materials guides and recycling guides as ‘may be suitable’ for recycling. The present work investigates the recyclability of EVOH barrier packaging due to the growing trends of multilayer rigid food packaging and more importantly, as recovery systems strive towards a better circular economy. The steps taken to produce food grade rHDPE with analysis included; Audits of the HDPE fraction at Viridor MRF, testing on automated NIR sorting equipment at Tomra (Titech), compounding in a low pressure, elevated temperature, food-grade decontamination process and overall migration testing conducted by Smithers-Pira. The evaluation showed that post-consumer HDPE (rHDPE) material containing at least 0.25% EVOH (equivalent to 5% multilayer EVOH/HDPE packaging) can be “super cleaned” to food grade quality without any significant impact on the process performance or physical properties compared to rHDPE only. The results showed that at the levels of multilayer EVOH packaging typically found in the recycled HDPE stream, the rHDPE can be processed and utilized in a full range of applications, without impact on migration characteristics or physical properties compared to rHDPE alone. Introduction Food packaging has seen significant changes over recent decades with demand for pre-packaged food increasing, hence the requirement for research and development in barrier and shelf life extending materials. Demand for food packaging resin is also increasing with HDPE behind PET but above PP and PS. [1][2] Packaging must comply with food safety regulations to protect the consumer, therefore multilayer structures are essential in preserving and protecting the food. In certain cases, packaging provides a barrier to gas permeation because of the risk of microbial activity and food spoilage, in other cases, functional barrier helps keeping the food away from external contaminants. In Europe, the Plastics Regulation (EU) No 10/2011 defines layer B as a “functional barrier” if it reduces the level of migration of a substance from layer A to layer C to a level where it can meet regulatory limits. Section VII from the Food and Drug Administration (FDA) ‘Guidance for Industry: Use of Recycled Plastics in Food Packaging: Chemistry Considerations,’ defines the use of an effective barrier. Kuraray is a world leader in EVOH (ethylene vinyl-alcohol copolymers) production and technology. An EVALTM layer thickness of only a few microns helps avoid spoilage by keeping oxygen and odours out, while locking flavours, aromas and modified atmosphere inside the package. This prolongs shelf life reducing the need for artificial additives to be added into food. Fewer resources can often be used for the same packaging function. Optimized portion size, light weight and extended freshness help improve the efficiency of storage, transport and display, saving costs and preserving resources. Kuraray quote that “1 mm of EVALTM provides about the same gas barrier properties as a 10 metre thickness of LDPE.” [4] EVOH will continue to be used in packaging for these reasons and ideally would be recycled with minimal detrimental effects in the polyolefin industry. It is well known that EVOH offers great barrier protection against oxygen, odours and gases however EVOH has also been reported to absorb significant amounts of moisture in humid conditions which is why multilayer structures are needed. Kuraray, EVAL Europe N.V. produces Ethylene Vinyl Alcohol copolymer (EVOH) which is used in blow moulded HDPE multilayer bottles to provide gas barrier SPE ANTEC Anaheim 2017 / 493 properties for juice or specialised milk products. Food grade recycled HDPE (rHDPE) is produced in UK and other countries, primarily from clear (natural) coloured monolayer blow moulded white (fresh) milk bottles and is used back into the manufacture of new milk bottles at approximately 15%, providing closed loop recycling of this material in the UK. The food grade rHDPE is a commercial material currently only available from a few suppliers, but it will be available from an additional number of recyclers in the UK and other countries in the near future. For PP, the recyclability characterization in the WRAP guidance states that EVOH if less than 10% of total pack weight is ‘not ideal’ (Category B) and if above 10% pack weight then it is classed as ‘detrimental’ (Category C). For HDPE milk bottle recyclability, co-extruded EVOH barriers are within category C. Category B recommends coextruded tie-layer functional polyolefins if less than 3% total bottle weight. These constraints could have better definitions to enable manufacturers of EVOH to participate in the circular economy with growing pressures on recycling. Kuraray, EVAL Europe N.V. wanted to investigate in detail that multilayer natural coloured HDPE/EVOH material can be effectively recycled as a percentage of the post-consumer stream and used back into food packaging and applications. Nextek assisted with conducting this study and trials and evaluation of the recycling process with blow moulded multilayer HDPE barrier bottles. Food grade rHDPE recycling involves sorting that removes colored HDPE, although some white is often retained. The performance of EVOH was also assessed during the food grade decontamination or super cleaning stage to confirm that the presence of EVOH does not negatively impact on the process or the properties of the final food grade material. Market applications and percentage of EVOH in