Versatile Packaging have recently been researching the development of solutions that enable the mechanical recycling of black plastic packaging that is currently destined for energy recovery.
We were getting many enquiries from our customers regarding the recycling status of the plastic trays we supply. In order for us to confidently answer the many queries from our customers regarding the recyclability of our plastic trays, we wanted to familiarise ourselves with the recycling process currently being used in Ireland. We were really trying to educate ourselves in the hopes to educate others.
We were pleased to discover that there are mechanical solutions in place for the recovery and recycling of rigid clear and coloured plastic packaging such as pots, tubs and trays from a mixed plastic waste stream.
However, currently the most common black pigments are based on carbon black that is not detectable by automatic Near infrared (NIR) sorting systems being used in most Material Recovery Facilities (MRFs), Plastics Recovery Facilities (PRFs) and at reprocessors to separate plastics into different polymer streams for reprocessing into valuable materials. Carbon black is the name of a common black pigment, it appears black because it reflects almost no light in the visible part of the spectrum and also strongly absorbs in the ultra-violet (UV) and infrared (IR) spectral range. Carbon black is used as a colourant in food contact packaging for a number of reasons including that it provides a contrasting background and allows the colours in the food to stand out. It is low cost, has good dispersion and masking properties which allows off cuts of other colours to be mixed together and manufactured into black items.
NIR identification trials of commercially available black plastic packaging confirmed that packaging coloured with carbon black cannot be detected by NIR systems and therefore ends up in the unsorted residue. Although the black trays are fully recyclable most on pack recycling labels for black plastic is “check local recycling”, as there is a particular issue for carbon black packaging. Even though it may be collected for recycling, there is a technical barrier to it actually being recycled back to virgin replacement resins. The conveyor belts in the recycling facilities are black, so it is almost impossible for optical sorters to distinguish between the black tray on the black belt.
Our Trays can now be supplied to you with identifiable colourants that are detectable by Near infrared (NIR) spectroscopy. The approach of using NIR detectable colourants was shown to work with APET, RPET, CPET, PP, HDPE and PS during large-scale trials at a MRF.
For the avoidance of doubt, the intention of our research project was to visit sorting facilities and put our trays to the test. Our black and coloured NIR detectable trays were all correctly identified by the optical NIR sensors and were sorted into the correct polymer stream in both the MRF and PRF facilities.