PETpla.net Insider 06 / 2016

MATERIAL / RECYCLING 26 PET planet insider Vol. 17 No. 06/16 www.petpla.net PET fines from recycled bottles A valuable raw material Today’s PET recycling facilities create high quality flake from post-consumer bottles. The process starts with automated sorting equipment which is used to remove unwanted prod- ucts from the incoming material stream. After the bottles have been pre-sorted and the labels have been removed, they are visually inspected and sorted by polymer type and colour. Once separated into clear and coloured streams, the bottles are ground and washed. During this process, PET fines are generated and usually removed along with other residues. With a proper pre-screening system in place, com- bined with a dryer, extruder and continuous melt filter, cus- tomers can now create a useable product from these fines. The purity requirements of the final product made of recycled PET bottles vary depending on the end user. The following table represents the purity levels typically required for flake used to produce thermoform sheet. Clear PET, thermoforming sheet Metal: < 10 ppm Paper: < 50 ppm Polyolefins: < 50 ppm Others: < 25 ppm Coloured flakes: < 500 ppm Light blue < 50,000 ppm (5%) PVC: < 10 ppm Adhesives: < 400 ppm Additives: < 1,200 ppm are separated during the screening and hot washing processes. This is precisely the reason why they are so difficult to utilise as a valuable raw material. Due to the small size of the PET particles, they have a larger surface area and hence absorb more mois- ture. Even with efficient degassing technology during the extrusion pro- cess, the IV values tend to drop signif- icantly. Additionally, higher contamina- tion levels block static screens quickly, making it a challenge to process this material, even with sophisticated back-flushing screen changers. As a result, a large majority of the PET fines are sold off at a very low price. When considering that even a small recycling facility can produce more than 20t of fines per month, finding a solution to filter this product could have a huge commercial impact on the bottom line. With a proper pre- screening system in place combined with a dryer, extruder and continuous melt filter, customers can now create a useable product from these fines. The “Eco” continuous melt filter manufactured by Ettlinger Kunststoff- maschinen GmbH plays a major role RECYCLING S P E C I A L The final quality of the PET flake is dependent on the composition of the incoming bales as well as the sort- ing technology used in the recycling facility. This represents a daunting challenge for the melt filtration system in re-pelletising, thermoforming and packaging tape lines, especially if the aluminium fraction dramatically exceeds the specified 10ppm. The challenge is all the more intriguing when it comes to applica- tions for the fines that are obtained when the PET bottles are ground. These fines contain a much higher percentage of contaminants because more paper, aluminium, and PCV