Recycling of food grade packaging using fluorescent marks

Transcription

1 Appendix Report Recycling of food grade packaging using fluorescent marks A report on the use of fluorescent marker technology to enable high speed automatic sorting and recycling of used plastic packaging into a range of applications including food grade packaging. Project code: PMP3-1 Research date: Date: July 216

2 WRAP s vision is a world in which resources are used sustainably. Our mission is to accelerate the move to a sustainable resource-efficient economy through re-inventing how we design, produce and sell products; re-thinking how we use and consume products; and re-defining what is possible through reuse and recycling. Find out more at PMP1-3 [WRAP, 216, Banbury, Recycling of food grade packaging using fluorescent marks] Written by: Edward Kosior, Edwin Billiet, Rafi Ahmad, Jonathan Mitchell, Martin Kay, Kelvin Davies. Front cover photography: PET packaging and shrink sleeve label viewed under UV light with and without fluorescent pigment (Left). Different pigmented labelled packaging viewed under UV light (Right). While we have tried to make sure this report is accurate, we cannot accept responsibility or be held legally responsible for any loss or damage arising out of or in connection with this information being inaccurate, incomplete or misleading. This material is copyrighted. You can copy it free of charge as long as the material is accurate and not used in a misleading context. You must identify the source of the material and acknowledge our copyright. You must not use material to endorse or suggest we have endorsed a commercial product or service. For more details please see our terms and conditions on our website at

3 Executive summary Sorting of used packaging for closed loop recycling back into food packaging requires positive identification and sorting of the recycled materials to a higher standard. The commercial operators of food grade recycling processes are under pressure to demonstrate the recycled materials meet relevant European Food Safety Authority (EFSA) criteria that requires at least 95% (PET) and 99% (HDPE) of the feed material must have been used for food contact in its first life. The initiation of closed loop food grade recycling of PP packaging is awaiting a viable technical solution to differentiate the food grade packaging. The objective of this project was to further develop the fluorescent marker technology investigated in earlier projects that has the potential to meet EFSA requirements and also open the scope to be implemented in different applications, enabling and facilitating the sorting of different polymers to a high degree of purity. The scope included the optimisation of fluorescent compounds, evaluation of their stability in the supply chain and the ability of the compounds to be effectively removed during the cleaning and decontamination process. The project investigated the viability of the technology and its capacity to be implemented in the UK and elsewhere. The project demonstrated that the use of commercial labels incorporating fluorescent markers can be used to sort plastic bottles and packaging with high levels of yield and purity. The addition of UV illumination to existing full scale sorting equipment was used to sort packaging with a range of fluorescent pigments. The project was able to demonstrate yields in the range of 88% to 96% and purity levels up to 1% in a single pass. This performance can meet the sorting requirements for food grade plastics especially recycled PET, HDPE (and potentially recycled PP) that require high purity levels. The project showed that commercial labels and markers were efficiently removed without any residues during the simulation of recycling operations ensuring that they would not persist in future applications. In addition, the high temperature extrusion processes encountered in re-melting of plastics created irreversible changes to most of the fluorescent chemical structures and deactivated the markers as shown by oven simulation tests. One of the markers was stable at extrusion temperatures, limiting its application to only those labels that can be efficiently removed during the recycling stages. The markers investigated were shown to withstand the environmental conditions in the packaging supply chain encountered by milk bottles (e.g. refrigeration, moisture and fluorescent lighting) without any significant change in performance. However, these markers were affected by exposure to outdoor UV light and the sorting efficiency after outdoor storage still needs to be validated even though baling of containers would protect the bulk of the labels. The fluorescent markers were used at low addition levels in inks at between 2, and 6,ppm and were effectively sorted on high-speed automatic sorting systems running at the throughputs of 3m/sec and 1 tonne per hour per metre of belt width that are typically found in commercial plants. At a concentration of 2,ppm, the pigment cost WRAP Recycling of food grade packaging using fluorescent marks 1 of 33

4 is of the order of per 1, labels depending on the pigment selected. The lower limit of detection of the current label/equipment system was shown to be in the region of 125ppm, providing opportunities for a further ten-fold pigment cost reduction. Calibration of the sorting equipment to identify the unique signature of a label by using the NIR signal combined with fluorescence provided a way of achieving high levels of discrimination and purity in sorting. Therefore, the polymeric composition of the label and the pigment can together become the unique identifier for the packaging. This will provide many combinations based on the opportunity to use materials such as PP, PS, LLDPE and PET as well as others, as sleeves and labels for selective identification and sorting of many applications. Tomra provided a preliminary cost estimate of systems and modification to achieve this unique signature with fluorescent labels at 1-2% of the cost of the existing NIR/Vis sorting unit. A protocol for the use of fluorescent markers in the recycling of packaging has been proposed using two different markers (red and yellow) in conjunction with the label composition and the packaging substrate to designate food-grade and specific non-food grade packaging respectively. Packaging that is food grade and natural in colour would be designated by the food grade marker DR-1 (red), and coloured packaging or any products that needs to be especially removed from a stream (e.g. non-food bottle that contained toxic products) would be designated by DY-1 (yellow). In the case of sorting food grade and coloured plastic, then a combined maker (DR-1 & SC-1) could be used. The signal from this combination would be different from the natural packaging food grade marker (DR-1) and different from the coloured non-food grade marker (DY-1). In order to separate bottles from pots tubs and trays, a combined maker of DR-1 and DY-1 would be used. This would be particularly useful for PET recycling where there is a desire to separate the two streams due to the differing recycling behaviour. The proposed protocol is summarised in the table below and each combination is unique even though the fluorescent pigment is the same allowing a simple and effective way of discriminating each material and any new materials that need to be added in the future. Table: Protocol for designation of fluorescent markers for Packaging. Bottle type Food grade natural Bottles and full length sleeves Food grade natural Pots, Tubs and Trays Food grade coloured and full length sleeve Non- food grade natural or coloured full length sleeve PET DR-1 DR-1 & DY-1 DR-1 & SC-1 DY-1 HDPE DR-1 DR-1 & DY-1 DR-1 & SC-1 DY-1 PP DR-1 DR-1 & DY-1 DR-1 & SC-1 DY-1 WRAP Recycling of food grade packaging using fluorescent marks 2

5 Other Polymers DR-1 DR-1 & DY-1 DR-1 & SC-1 DY-1 The widespread use of optical brighteners in labels, plastics colorants and liquid products such as detergents means that there could be cross over with fluorescent pigments that emit in the blue region leading to false positives in sorting. For this reason, it is recommended that markers that fluoresce in the blue wavelength spectrum are specifically not used on their own. The final protocols would be based on approved combinations of a range of resins used for labels and sleeves along with the specific pigments used as fluorescent markers. This would involve a registration and profiling the spectrum of each combination of label, fluorescent material and base packaging material. This would generate a database of approved and unique signatures for the packages that would be used to program the sorting equipment made by the various manufacturers. The approval process would need to be established on a national and preferably a regional basis to avoid standardisation conflicts when products are marketed in many countries or globally. This project has demonstrated that sorting processes based on fluorescent labels can provide an additional level of information to allow further sub-categorisation of packaging either at the start of sorting or after a primary sorting step. The recycling of food grade PET packaging, food grade HDPE milk bottles and PP rigid packaging are likely starting points for the application of this technology. WRAP Recycling of food grade packaging using fluorescent marks 3

6 Contents Appendices... 6 Appendix 1: Evaluation of fluorescent markers Appendix 2: Effect of label backing material and manufacture processes Appendix 3: Effect of lighting exposure in the supply chain Appendix 4: Impact of weathering on fluorescent markers Appendix 5: Bottle wash trials Appendix 6: Cost estimates Figures Figure A1-1: Emission spectra of a range of compounds initially tested using UV-LED Figure A1-2: Individual and summed emission spectra of selected pigments... 8 Figure A1-3: Emission spectra of mixed selected pigments... 1 Figure A2-4: Emission spectra of UVC treated labels Figure A3-5: Images of dairy display at retailers Figure A3-6: Label positioning in dairy cool room storage Figure A4-7: Effect of weathering on fluorescent pigments Hand drawn labels Figure A4-8: Power Law equation for extrapolation of effect of UV exposure Figure A4-9: Effect of weathering on pigments Commercial labels Figure A5-1: Labelled bottle and Flake samples under UV before and after washing Figure A6-11: Bench scale and commercial sorting lighting configuration... 3 Tables Table A2-1: Effect of UVC curing on marker emission Table A3-2: Summary of dairy lighting at six retailers Table A3-3: Emission intensity after dairy cool room exposure Table A6-4: Pigment quantities and cost per thousand labels WRAP Recycling of food grade packaging using fluorescent marks 4 of 33

7 Glossary Counts Emission Intensity Fluorescent HDPE IR LED LDPE LLDPE MRF ms NIR nm PET PP Unit of measure of Emission Intensity during the integration time. Strength of emitted radiation from fluorescent substance A substance that emits longer wavelength radiation (visible light) while being excited by shorter wavelength radiation (non-visible UV) High Density Polyethylene Infrared Light Emitting Diode Low density polyethylene Linear low-density polyethylene Material Recovery Facility milliseconds Near-Infrared nanometre Polyethylene terephthalate Polypropylene ppm parts per million (1 6 ) PS PSA ti UV UVC UV-LED Polystyrene Pressure Sensitive Adhesive (label) Integration time (ms), refers to the time the detector is open to the radiation emission from the fluorescent pigment. Ultra Violet Ultra Violet in the C region 2-28nm Light emitting diode that emits in the UV region (365nm) WRAP Recycling of food grade packaging using fluorescent marks 5

8 Emission Intensity (counts) Appendices Appendix 1: Evaluation of fluorescent markers Selected compounds, obtained from a number of sources, were prepared by mixing pigments with a nitrocellulose lacquer and Ethyl Acetate solvent in a high-speed mixer. Pigment concentrations were varied in the lacquer /solvent solutions as required, then by use of Myer bar (K1.5) and a rubber pad a 1micron wet lacquer was deposited onto an A4 size sheet of self-adhesive PP film and allowed to air dry. This was then cut to size and used to prepare test specimens for spectrometer testing and the preparation of labels for testing with automatic sorting. Using a test jig, the samples were mounted in slide carriers and illuminated with various light sources in order to induce emission. They were; 365nm, 64nm, 84-98nm and 42-72nm. The emitted light from the pigment was collected at 5cm distance with a telescope focussing onto a fibre optic and the emission spectra measured on an Ocean Optics Spectrophotometer. The spectra in Figure A1-1 provide an overview of the emission intensity and peak emission wavelength of the different pigments as a comparison. It can be seen that some pigments are essentially identical in response, and many have similar and overlapping emission wavelengths that would be difficult for automatic sorters to differentiate, meaning that they could not be used in combination. Figure A1-1: Emission spectra of a range of compounds initially tested using UV-LED. 5, Selection of Pigment Spectra 45, 4, 35, 3, 25, 2, 15, 1, 5, Wavelength (nm) SG-1 DY-1 DR-1 SC-1 SL-1 BS-4 BS-2 SR-1 VM-2 VM-3 WRAP Recycling of food grade packaging using fluorescent marks 6 of 33

9 Emission Intensity (counts) 15, Selection of Pigment Spectra - rescaled 1, 5, Wavelength (nm) SG-1 DY-1 DR-1 SC-1 SL-1 BS-4 BS-2 SR-1 VM-2 VM-3 These spectra utilised pigment concentrations of 6,25ppm and an integration times of 1ms to obtain results for comparison on a similar scale, with the following exceptions; BS-4 31,25ppm and 5ms. SR-1 3,125ppm and 5ms VM-2 6,25ppm and 2ms VM-3 6,25ppm and 2ms A further element of the project was to demonstrate if different pigments could be used in combinations to provide additional information and sorting options. For example if three pigments with different spectra were suitable for use, up to seven [2 3-1=7] different articles could be identified if they could all be used in various combinations. Based on their emission spectra and weathering results, four pigments were evaluated initially by summing their individual spectra and then by physical mixing of selected pigments which were then applied to PP label backing for testing. Pigment DR-1 had the most pronounce spectra which was summed with SC-1, DY-1 and SL-1 pigments to provide an indication of the overall spectra and the potential for selective detection and identification. WRAP Recycling of food grade packaging using fluorescent marks Page : 7 of 33

10 Emission Intensity (counts) Emission Intensity (counts) Figure A1-2: Individual and summed emission spectra of selected pigments 6, Individual emission spectra of pigments 5, 4, 3, 2, 1, Wavelength (nm) SL-1 DY-1 DR-1 SC-1 6, Sum DR-1, SC-1 and DY-1 pigments 5, 4, 3, 2, 1, Wavelength (nm) WRAP Recycling of food grade packaging using fluorescent marks Page : 8 of 33

11 Emission Intensity (counts) Emission Intensity (counts) 6, Sum DR-1 and SC-1 pigments 5, 4, 3, 2, 1, Wavelength (nm) 6, Sum DR-1 and DY-1 pigments 5, 4, 3, 2, 1, Wavelength (nm) WRAP Recycling of food grade packaging using fluorescent marks Page : 9 of 33

12 Intensity emission (counts) Figure A1-3: Emission spectra of mixed selected pigments 6, Emission spectra of mixed DR-1 and DY-1 pigments 5, 4, 3, 2, 1, Wavelength (nm) WRAP Recycling of food grade packaging using fluorescent marks Page : 1 of 33

13 Appendix 2: Effect of label backing material and manufacture processes Some results suggested that the use of a backing film can enhance the fluorescent intensity when the light is reflected and able to pass back through the lacquer a second time. This would allow a reduction of pigment concentration therefore reducing the cost of the label or the possible use of otherwise lower cost and lower intensity emitters. Samples were analysed to measure the effect of two types of reflective backing paper, one that had its own background fluorescence, and one that had no inherent fluorescence. The detector integration time (ti) is an important factor for high speed automated sorting and attention paid must be made of the time it took to develop each spectrum. Use of Ultra Violet light in the range of 2-28nm (UVC) radiation for the drying and curing inks is a common commercial process used for making printed labels. A preliminary evaluation was conducted to measure the effect of the UVC on the emission of the fluorescent markers. Labels were prepared by CCL using SR-1 in lacquer at concentrations of 17,7ppm and 69,7ppm then cured with exposure to UVC directly onto the lacquer (the front/print facing of the label) and also indirectly (the back/adhesive side of the label). Emission spectra were measured using prepared slides on the bench scale jig, for controls and each variable. Results are presented in Table A2-1 and Figure A2-4. Table A2-1: Effect of UVC curing on marker emission. Label Pigment (ppm) Detection Time (ms) Peak Intensity (@ 615nm) Without Marker Marker only 17,7 5 24,629 Marker with front treated UV 17,7 5 13,15 Marker with back treated UV 17,7 5 24,815 Marker only 69,7 5 55,83 Marker with front treated UV 69,7 5 53,133 Marker with back treated UV 69,7 5 41,37 WRAP Recycling of food grade packaging using fluorescent marks Page : 11 of 33

14 Emission Intensity (Counts) Emission Intensity (Counts) Figure A2-4: Emission spectra of UVC treated labels 3, CCL Labels - SR-1 concentration 17,7 ppm 25, 2, 15, 1, 5, Wavelength (nm) no UVC UVC print side UVC adhesive side 6, CCL Labels - SR-1 concentration 69,7 ppm 5, 4, 3, 2, 1, Wavelength (nm) no UVC UVC print side UVC adhesive side Results show that the brief but intense UVC treatment can reduce emission intensity; however, a large amount of the activity remains. Further experimental testing is recommended with other fluorescent markers and at other concentrations to understand any influence of UVC treatment during commercial label making processes. WRAP Recycling of food grade packaging using fluorescent marks Page : 12 of 33

15 Appendix 3: Effect of lighting exposure in the supply chain Lighting systems at supermarkets dairy display case were assessed to determine if there was any potential for this lighting to impact on the performance of the pigments. It was not possible to conduct trials by placing labels in situ in these public places, so the type and power of the lighting systems was documented and compared with exposure conditions results from bench scale weathering testing. These results show that for some pigments like SR-1 and DR-1, 6 days of constant fluorescent lighting can reduce emissions by more than 5%, however after this time the pigment remains active and have sufficient intensity to be detected by sorting equipment. Other pigments like DY-1 and SC-1 are minimally affected by the fluorescent lighting of supermarket display cases. Table A3-2: Summary of dairy lighting at six retailers Retail store Lighting type and rating Store 1 Store 2 Store 3 Store 4 Store 5 Store 6 Osram TLD36W/84 Unknown rating 17W LED LED unknown rating Milk dairy chill cabinet stated Lighting 16W -fluorescent bulbs were unmarked (rating unknown). Fluorescent bulbs in adjacent dairy produce chiller are labelled L36W/84 Osram L36W/83 Figure A3-5: Images of dairy display at retailers Lighting - TLD 36W/84 Lighting LED 17W WRAP Recycling of food grade packaging using fluorescent marks Page : 13 of 33

16 Lighting LED (unknown rating) Lighting - Osram L36W/83 Labels made with different pigments were also placed in a commercial dairy storeroom, to evaluate the impact of ambient lighting might have on labels that would be filled bottles and stored for up to 15 hours. Labels were placed face up on top of racks to maximise exposure. Figure A3-6: Label positioning in dairy cool room storage Results show that cool room lighting at this dairy storeroom had no impact on the emission intensity of the label samples. Peak intensity before and after cool room, storage was within normal variation limits of the hand drawn samples. WRAP Recycling of food grade packaging using fluorescent marks Page : 14 of 33

17 Table A3-3: Emission intensity after dairy cool room exposure Pigment code name Peak Emission Wavelength (nm) Unexposed control (counts/ 1ms) Dairy Exposure (counts/ 1ms) Change after exposure (%) SR , 83, -9 SL ,9 9, SC , 4, DR , 45, SG ,33 5,82 1 DY ,933 9,414 5 BS ,3 1,69-18 BS , 46, The large increase in emission for sample BS-2 may also be due to inconsistent pigment concentration of pigment in the hand drawn coating label samples. WRAP Recycling of food grade packaging using fluorescent marks Page : 15 of 33

18 Emission Intensity (counts) Appendix 4: Impact of weathering on fluorescent markers The influence of storage and ambient conditions was assessed for a range of pigments to evaluate their light fastness and stability under a range of conditions. Four test conditions were selected as indicative of conditions that packaging might be experience in the supply chain; Outside: Samples South facing at a 3 angle 1.5m above the ground. Refrigerator: Samples in a polyethylene bag on door shelf at 5 C Freezer: Samples in a polyethylene bag on upper shelf at-25 C Fluorescent tube: Samples on a 3cm from a 3W, 9cm daylight tube. The refrigerator and freezer samples were placed in polyethylene bags to eliminate condensation that formed when they were removed from storage conditions and was found to affect the spectrophotometer readings. During refrigerator and freezer storage, samples were effectively in the dark, away from any ambient lighting. Samples were periodically collected and emission intensity readings measured to monitor any change in performance over a 15 days period. The outside exposure was the least controlled conditions, essentially dependant on the winter weather for fifteen days from the 3/1/216 to 21/1/216, in Swindon UK. The spectrophotometer readings for a wide range of pigments are presented in Figure A4-7 over the 15 days period. Although some pigments are more affected by weathering, particularly sunlight and fluorescent lighting, their residual emission is still greater than that of some pigments that are less affected by the weathering. The vertical scale of the charts in Figure A4-7 differs in order to show the impact or weathering. Note of the vertical scale should be made when making comparisons of the intensity of the different compounds. Figure A4-7: Effect of weathering on fluorescent pigments hand drawn labels. 1,2 Pigment SG-1 1, Day fridge freezer fluor' tube outside WRAP Recycling of food grade packaging using fluorescent marks Page : 16 of 33

19 Emission Intensity (counts) Emission Intensity (counts) Pigment DY-1 1, Day fridge freezer fluor' tube outside Pigment DR-1 6, 5, 4, 3, 2, 1, Day fridge freezer fluor' tube outside WRAP Recycling of food grade packaging using fluorescent marks Page : 17 of 33

20 Emission Intensity (coounts) Emission Intensity (counts) Pigment SC-1 3, 2,5 2, 1,5 1, Day fridge freezer fluor' tube outside Pigment SL-1 1,2 1, Day fridge freezer fluor' tube outside WRAP Recycling of food grade packaging using fluorescent marks Page : 18 of 33

21 Emission Intensity (counts) Emission Intensity (counts) 12 Pigment BS Day fridge freezer fluor' tube outside 1,2 Pigment BS-2 1, Day fridge freezer fluor' tube outside WRAP Recycling of food grade packaging using fluorescent marks Page : 19 of 33

22 Emission Intensity (counts) 1, Pigment SR-1 8, 6, 4, 2, Day fridge freezer fluor' tube outside For samples with outdoor exposure, it is thought that moisture and condensation on the surface of the labels caused some unexpected increases in emission intensity during testing. However, the overall sensitivity and trend in the reduction of emission intensity can be seen for each sample. Samples are largely unaffected by refrigerator and freezer conditions, however some pigments are significantly affected by UV exposure from sunlight or fluorescent lamps. The long-term effects of UV exposure were calculated for pigment SR-1, by extrapolation using a power law equation and shown on a log base 1 scale in Figure A4-8. WRAP Recycling of food grade packaging using fluorescent marks Page : 2 of 33

23 Emission Intensity (counts) Figure A4-8: Power Law equation for extrapolation of effect of UV exposure. 1, Pigment SR-1 1, y = x -.69 y = x Day fluor' tube outside Power (fluor' tube) Power (outside) Based on the calculations it has been estimated that when exposed to 5 days of direct sunlight the performance of the SR-1 pigment at 1,ppm would be reduced to an emission intensity at or below detection limits for commercial sorters. Under fluorescent tube exposure, the period is approximately 1 days. Label samples made by CCL where also tested later in the project, under similar exposure conditions. These results confirmed that the hand drawn samples on selfadhesive PP backing and the shrink sleeve, PSA, and stretch sleeve labels made by a commercial process have similar levels of performance, dependant only on the pigment type. The graphs in Figure A4-9 show the impact of 1 days of weathering on the emission intensity of all of the label types that were used in the Tomra sorting trial. Emission Intensity was measured at two wavelengths 472nm and 437nm for the SC-1 pigment, either or both of which could be used for identification, no significant differences were observed between the two peak emission wavelengths. The emission wavelength monitored for DR-1 and DY-1 is noted in the graph titles. WRAP Recycling of food grade packaging using fluorescent marks Page : 21 of 33

24 Emission intensity (counts) Emission intensity (counts) Figure A4-9: Effect of weathering on pigments commercial labels. Pigment DR-1, 2,ppm - Shrink 8, 6, 4, 2, Days Fridge Freezer Fluor Lamp Outside Control Pigment SC-1 only, 2,ppm - PSA 1, 8, 6, 4, 2, Days Fridge Freezer Fluor Lamp Outside Control WRAP Recycling of food grade packaging using fluorescent marks Page : 22 of 33

25 Emission intensity (counts) Emission intensity (counts) Pigment SC-1 only, 2,ppm - PSA 1, 8, 6, 4, 2, Days Fridge Freezer Fluor Lamp Outside Control Pigment DR-1 & SC-1, 2,ppm - PSA 4, 3, 2, 1, Days Fridge Freezer Fluor Lamp Outside Control WRAP Recycling of food grade packaging using fluorescent marks Page : 23 of 33

26 Emission intensity (counts) Emission intensity (counts) Pigment DR-1 & SC-1, 2,ppm - PSA 1, 8, 6, 4, 2, Days Fridge Freezer Fluor Lamp Outside Control Pigment DR-1 & SC-1, 2,ppm - PSA 1, 8, 6, 4, 2, Days Fridge Freezer Fluor Lamp Outside Control WRAP Recycling of food grade packaging using fluorescent marks Page : 24 of 33

27 Emission intensity (counts) Emission intensity (counts) Pigment DY-1, 6,ppm - PSA Clear 2, 1,5 1, Days Fridge Freezer Fluor Lamp Outside Control Pigment DY-1, 6,ppm - PSA White 4, 3, 2, 1, Days Fridge Freezer Fluor Lamp Outside Control Similar levels of reduced emission intensity are seen with pigments DR-1 and SC-1 that were observed with the hand drawn label samples. The DY-1 pigment, which was not previously tested, shows significantly improved stability to UV exposure from fluorescent and outdoor conditions. WRAP Recycling of food grade packaging using fluorescent marks Page : 25 of 33

28 Appendix 5: Bottle wash trials Bottles with commercial labels that were used in the Tomra sort trial were sent to Sorema for granulation and wash trials. Sorema is well known globally for its high quality wash systems for PET and HDPE recycling, particularly for food grade bottle-tobottle recycling systems for which very high quality washed flake is required. Sorema conducted bench scale testing in its laboratory facility, after granulation, bottle and label material was washed, rinsed to remove residual caustic, then dried and labels separated from the flake using an air classifier, which is a common process sequence for recycling. Standard wash conditions that are commonly used for PET and HDPE were used; 85 C for 6-1 min. Caustic soda (3% solution) at 2-4% RP 24 (MacDermid) surfactant Results in Figure A5-9 show that the label was completely removed from the bottle for all types of label. The marker appears to have retained its fluorescence through the wash system, which will minimise any contamination of the wash water. Figure A5-1: Labelled bottle and Flake samples under UV before and after washing Bottle/ Label type Washed Flake & Label under UV lamp WRAP Recycling of food grade packaging using fluorescent marks Page : 26 of 33

29 Thermal stability testing have shown that extrusion and moulding conditions to pelletise or reform new products effectively neutralises all traces of fluorescent in the pigments, should a small amount of fluorescent label material remain with the polymer. The combination of excellent label removal from the wash process and the effect of extrusion conditions ensure that the possibility of positive contamination of recycled material is extremely low. WRAP Recycling of food grade packaging using fluorescent marks Page : 27 of 33

30 Appendix 6: Cost estimates The use of fluorescent markers on labels to improve sorting will likely result in additional costs to the supply chain, however by optimising the performance and detection, these costs can be minimised to a small percentage of overall packaging costs. Sorting trials reported successful identification using commercial label samples with pigment concentrations at 2,ppm, information from the sorting trial indicates that pigment levels as low as 125ppm would be detectable. From bench scale trials it was shown.15ml of lacquer solution was required for a 1cm x 1cm label. Based on concentrations tested in the project and pigment material price, the amount and cost of the three pigments used in trials was calculated on a per thousand label basis, and as a percentage of the current label cost estimated at.75 pence 1 per label as shown in Table A6-4. The additional pigment costs per thousand labels is shown in Table A6-4 for a range of concentrations. These have been estimated as.5% for lowest cost pigments at 125ppm, to 3.% for highest cost pigment at 2,ppm, respective of the.75 pence price of an applied label, for the pigment material only. There may also be some additional material costs for lacquers or coatings and additional operational costs dependent on the final label structure. Table A6-4: Pigment quantities and cost per thousand labels. Concentration 12,5ppm 6,ppm 2,ppm 125ppm Pigment / 1, labels (mg) 1, Pigment volume 2 pa (tonne) Pigment DR-1 Cost 75/kg Pigment cost / 1, labels ( ) Pigment cost (% of label cost) Pigment DY-1 Cost 416/kg Pigment cost / 1, labels ( ) Pigment cost (% of label cost) Pigment SC-1 Cost 19/kg Pigment cost / 1, labels ( ) Pigment cost (% of label cost) IMT3-13) - Sorting plastics for food use. WRAP For 14.3 billion PP packaging trays with a 1cm x 1cm label. WRAP Recycling of food grade packaging using fluorescent marks Page : 28 of 33

31 As an application example, using the 143, tonne of PP packaging 3 that is produced every year, this equates to 14.3 billion 1g packs per year and.27 tonne of pigment at 125ppm or 4.3 tonne at 2,ppm, as shown in Table A6-4. Suppliers have indicated that pigment purchase cost would likely decrease over time as process costs were reduced with volume increases, and this would bring down application costs further 4. Sorting trials used the same UV-LED lamp assembly as was used in the previous WRAP project 5. Existing commercial sorting equipment can be modified with this type of lighting system to enable the detection of the fluorescent marker labels. Costs to retrofit the new lamp and detection requirements are dependent on factors including age, condition and whether the sorting unit was configured for detection and sorting in the visible spectrum, or in the NIR spectrum only. Project partner Tomra provided a preliminary estimate of the cost of the additional UV-LED lighting systems showing modifications at 1-2% of the cost of the existing NIR/Vis sorting unit. These cost estimates may increase if other upgrades are required to older or minimally configured sorting units Lamp design is an important aspect as it affects the pigment selection and minimum concentrations for reliable detection. An experimental design and configuration used for trials was successful, however it may be further improved which will further reduce pigment and label costs as well as improve yields and purity. To illustrate Figure A6-11 shows a schematic highlighting the differences between the bench scale test jig used in the assessment of pigments and that used by Tomra in the commercial sorting trials 3 UK market compositional data of polypropylene packaging, WRAP Based on anecdotal information from discussion with suppliers 5 IMT3-16 Optimising the use of machine readable inks for food packaging. WRAP September 214 WRAP Recycling of food grade packaging using fluorescent marks Page : 29 of 33

32 Figure A6-11: Bench scale and commercial sorting lighting configuration Nextek bench test arrangement UV LED Separation (S1) Tomra commercial trials UV LED Separation (S2) 1 fwhp Dispersion angle 7 fwhp Dispersion angle LED to test sample Footprint (F1) LED to Conveyor (L2) Footprint (F2) The design of the lighting system directly affects the power density on the label which when combined with label size and pigment concentration determines the detectability of the packaging. It may be possible to increase power density to enable lower emitting pigments or lower concentrations of pigments to be detected, however this may also add to modification capital costs. Trials also identified the potential benefits of using specific filters to improve specificity of identification, particularly for fluorescent labels and inert background label colours, and these optimisation options require further research. WRAP Recycling of food grade packaging using fluorescent marks Page : 3 of 33

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