FR3010789A3 - DEVICE FOR AUTOMATICALLY IDENTIFYING FLUORESCENCE OF PLOTTERS FOR THE AUTOMATIC SORTING AND / OR QUALITY CONTROL OF COLORED OR NON-COLORED PRODUCTS OR MATERIALS. - Google Patents

Abstract

The invention relates to a device (1) for the identification and / or authentication of a material (2) or an object, in particular for sorting dark or black plastics containing chemical tracers to concentrations of less than 50 ppm, comprising: - a source (3) of a UV or IR excitation radiation (4); a fluorescence detector (6) emitted by the material (2) subjected to said radiation; - Processing means (8) for detecting and identifying the tracers. The invention also relates to a method using such a device.

Description

Device for the automatic identification of fluorescence of tracers for automatic sorting and / or quality control of colored or unstained products or materials.

Objective: to identify at high speed objects, particles or materials, automatically, without contact, and to deliver a signal that can be coupled to a sorting device (positive or negative sorting by ejection) or likely to create an alert ( Quality Control). PRIOR ART The concept of a system for tracing virgin polymers for sorting has developed since the years 1993. The first patent filed [British Petroleum Company, 1993] describes a method for identifying polymers by fluorescence detection of certain tracers based on rare earths in the spectral range of near infrared (NIR) between 700 and 900 nm for tracer concentrations of 0.001 ppm to 1 ppm. The source used is a laser diode that emits in the NIR at 670nm. The disadvantage of this method is the difficulty of detecting a signal in NIR when the matrix is dark. The carbon black used as a dye absorbs all radiation in the NIR [Eisenreich, 1992]. A patent filed in 1994 [Bayer, 1994] describes two tracer systems having different fluorescence emission wavelengths and for each system tracers having different fluorescence times. The identification principle allows coding with 4 tracers. This method is currently used in the field of biochemistry, the experimental system includes a flash lamp and a programmable camera to postpone the triggering of the image taking a few nano seconds after excitation by the source. This system therefore makes it possible to identify molecules that have the same fluorescence emission wavelength but not the same duration. This method seems difficult to set up at the level of rapid and automated sorting because in the case of industrial systems the samples to be sorted are illuminated continuously and in this case, it is impossible to differentiate the fluorescence times to differentiate tracers.

In 1998 another study funded [Simmons et al., 98] [Ahmad, 2000] by a European program resulted in a first pilot for a sorting application of plastic bottles in the packaging sector. The system allowed, from a coding based on combinations of three tracers at concentrations between 0.5 and 20 ppm, to identify bottle packs made of HDPE. Patents on the identification system have been filed by the program partners [Lambert, 2004]. The pilot bench did not identify dark colored polymers and no testing was done on other types of polymer matrices. In 2005 a patent [ERIEZ, 2005] was filed on the magnetic sorting of polymers containing magnetic tracers. In 2007, a tracer study validated the automated rapid sorting of black ground polypropylene [Froelich, 2007]. In the same study, a state of the art was carried out on the various tracing technologies [Froelich, 2007]. Two technologies have been validated for the sorting of black polypropylene: the detection of magnetic tracers and the detection in X rays fluorescence of tracers based on rare earths. In 2008, a thesis was funded by the ADEME (Agency for Development and Control of Energy) to perform laboratory tests for X-ray fluorescence detection [Bezati et al, 2010]. The results of this work show that detection by magnetic tracers is industrially viable but does not allow coding with several tracers. X-ray fluorescence detection allows the detection of rare earth oxide tracers at 1000 ppm in black or painted polymers. The absorption of X-ray fluorescence by the molecules of the ambient air does not make it possible to reduce the tracer concentrations to less than 100 ppm and the detection times are still long compared to industrial fast sorting constraints. The choice of tracers is limited to rare earths. In conclusion, these different patents and studies (Tab.2) have all validated the technique of tracing polymers but these technologies are not suitable for dark colored materials or for reasons of industrial constraints including fast sorting in 10ms.

The technology that is the subject of the patent is the UV-Visible fluorescence because it is able to detect low concentrations and meet the constraints of recyclers and end-users. Two patents were filed in 2010 by [Lambert, 2010] on the concept of tracing polymers for recycling and counterfeiting. Detection Technique Reference System Tracer Source wavelength Plastic materials Detection stage Development Intensity of British Petroleum Company, 1993 Rare earths 0.001 to lppm Emission at 670 nm Diode Transparent polymers fluorescence laboratory Detection between 700 and 900nm Duration of Bayer, 1994 Fluorophore Having Flash Fluorescence Laboratory Lamp of Different Fluorescence Times Intensity of (Simmons et al, Phosphor UV Excitation Detection: Visible Lamps Industrialized Fluorescence Lamp 98) (Ahmad, Technology, Ltd 'Transparent Xenon or Sorting Pilot at 2000) (Lambert, 2004) . 0.5ppm at 20ppm lightly colored, a packaging waste speed ... 3.5m, with s 95% purity Magnetic sensing Eriez Electromagnetic or Magnetic Particle Magnet Magnomagnetic Magnetics'2005 Industrial Magnet or Fall: Polymag c = 1% metal detector in ABS, PE, thermoplastic elastomers: TPE Intensity of Froelich et al, Rare Earth Oxide 0.1% Excitation X10 to X-Ray Generator Polymers with laboratory X-ray fluorescence 2007 Skev emission: 20 to SOkevX carbon black Bezati et al, 2010 Ahmad, SRA, 2004. New technology for automatic identification and release of plastics for recycling. Environmental Technology 25 (10), 1143-1149. Bayer, Method for identification of plastics, 1994, Patent US5329127A. Bezati, F., Froelich, D., Massardier, V., Maris, E., 2010. Addition of tracers in the polypropylene in the field of plasticization using X-ray fluorescence spectrometry. Waste Management 30,591-596.

Eriez, Patent US6920982, 2005 Froelich, D., Maris, E., Massardier, V., state of the art technico-economic techniques and processes for incorporating tracers into polymeric materials, for the purpose of automated sorting plastic waste from end-of-life products. Report No. 050907 / 1A, 2007, RECORD, French Industry-University Cooperative Research Network on Waste. Lambert, C., Hachin, J.M., 2004. Method for Authentication by Chemical Marking or Tracing of an Object or a Substance, Patent WO2004040504.

Lambert, C., Hachin, JM, Method for Identifying a Substance or Object Using a Plurality of Vectors, 2010, Patent US2010089804A1 Lambert, C., Hachin, JM, Method for Identifying a Substance or Object Using a Plurality of Vectors, 2010, Patent US2010089804A1.

Reuter, M.A., van Schaik, A., Ignatenko, O., Haan, G.J., 2006. Fundamental limits for the recycling of end-of-life vehicles. Minerals Engineering 19 (5), 433-449. Maris, E., A. Aoussat, Naffrechoux, E., Froelich, D. Polymer tracer detection systems with UV fluorescence spectrometry to improve product recycling. Undermine. Eng. (2011), doi: 10.1016 / j.mineng.2011.09.016 lo Issues to be solved Recycling materials from end-of-life products is essential to preserve our non-renewable resources and reduce our impacts on climate change, the effects on human health and ecosystems. Several brakes on the recycling of materials exist, technical brakes and brakes related to the social acceptability of recycled materials. There are still several technical barriers to recycling materials from end-of-life products. These products are collected and treated at the end of their life, this leads after grinding to sorting complex mixtures [Reuter, 2005] which at the beginning at the level of a product could be eco-designed. Another brake is related to the two types of industrial sorting technologies most representative of the recycling sector which do not make it possible to sort materials by physicochemical sorting such as densimetric sorting when the densities overlap and by fast NIR spectrometric sorting. the polymers are dark in color. In 2009, 24.3 million tonnes of plastic waste were generated in Europe and 25 only 22.5% on average were recycled across all sectors (PlasticsEurope, 2010). The barriers to social acceptability lie in the traceability of toxic substances potentially contained in recycled materials and waste that is found in the seas because they are not recycled. A proposal is therefore to add a new property specific to the material (signature, marking) that can be detected in order to identify the material with an automated rapid industrial sorting machine. Tracer / polymer systems were developed from laboratory tests, detection tests were performed to detect the signals of these systems.

This solution involves developing a detection device dedicated to the identification of light and dark colored polymeric materials containing low concentrations of tracers. These concentrations are preferably less than 1000 ppm and should be detected in black materials. Concentrations are preferably from 0.1ppm to 1000ppm. Low concentrations do not alter the properties of the plotted materials, are less expensive and difficult to counterfeit. Requirements: - fast response (therefore automatic) - can be coupled or integrated with an automatic sorting device or warning device (quality assurance) - contactless and remote (eg: 30cm) - little or no moving part - little sensitivity to the environment (eg dust) or transport medium (carpet) -programmable (depending on matrices, tracers, positive or negative choice, new formulations such renewable origin, nature of the loads ...) and adjustable according to the purity or the desired grade (setting a confidence interval ...) -duration of life (several thousand hours), hence important choice of the source of excitation -sensitive even to very weak signals: detection of tracers even at very low concentrations (hundreds at ppm fraction) - signal processing allowing the identification of tracers in matrices not only colored but also black - ability to identify not only e-type objects mballages but also small surfaces such as chips, particles or powders (AQ) Note: do not forget that identical detection system in the visible and near infra-red, It is possible to excite in the ultra- violet (Stokes effect) or around 900-1000 nm (anti-Stokes effect).

Description of the system for identifying objects, particles or materials at high speed by detecting a tracer signature. Tracer excitation is for example in the field of ultraviolet (stokes tracers) or infrared (anti-stokes tracer) and detection of the polymer-tracer system is for example in the visible in the UV or infrared. This configuration is very favorable for light and dark colored plastics. The acquisition time is between 1 and 10 ms minimum. The speed of travel of the crushed plastic particles is between 1 and 5 m / s and preferably at 3 m / s.

The excitation wavelengths of the tracers, will be included for the UV between 280 and 400 nm but may be extended to other wavelengths. For IR excitation, the lengths may range from 870 to 1100 nanometers, preferably from 970 to 1100 nm. The fluorescence lifetime of the tracers must be compatible with the speed of the particles of traced materials that run on the conveyor.

Sources at dP, s Processor Unit DLE.ce a1-.1a, .tique Conveyor System Ejection System The system that is the subject of the patent includes a system of reading automated sorting high speed, parts, particles, to identify composed of a material additive fluorescent tracers. The signal detected to identify the traced materials is a fluorescence intensity at specific wavelengths of the tracers. The choice of tracers and their concentration are dependent on the detection system, the fluorescence of the polymers and the fluorescence lifetime of the tracers, the particle size and their speed on the conveyor. The approach taken for the choice of tracers and their concentration is 1. to analyze the fluorescence of the materials to be plotted 2. to determine an excitation and emission window where the fluorescence of the materials is weak 3. To choose a tracer adapted to the material and to existing reading materials on the market. 4. Calculate the tracer concentration to have a signal on noise for high speed detection with a 95% confidence interval.

A detection window favorable to the detection of tracers incorporated into the materials. Polymeric materials have a greater or lesser degree of fluorescence depending on the excitation and emission wavelengths. To detect a tracer in low concentration it is interesting to have a signal ratio on a high noise, the noise being due to the materials must be low and that of the reading system, so that the noise signal of the tracer is detectable with a confidence interval compatible with industrial sorting. This range is preferably greater than 95%. The reading system includes: - A UV or IR source - A fluorescence signal detection system (visible, IR, UV) - A signal processing system to identify the polymer-tracer system - A carpet The configuration of the system of reading adapts to an industrial conveyor for the automated sorting of plastic waste either on a carpet or in free fall and the size of the particles of crushed materials with particle size between 5mm and 200mm but preferably between 30 and 60mm for a speed of particles preferably of 3m / s. Polychromatic or monochromatic sources: For UV: Lasers, laser diodes, LEDs, gas tubes such as xenon lamp or mercury lamp, operating in pulsed or continuous mode, with or without a reflector, condenser , provided or not with filters for example interferential to select the right excitation wavelengths of the tracers and provided or not with optical fiber to carry the radiation, For the IR: Lasers, laser diodes, LEDs, lamps like for example, filament lamps, operating in pulsed or continuous mode with or without a reflector, condenser, provided or not with filters, for example interferential, to select the right excitation wavelengths of the tracers and provided or not of optical fiber to carry the radiation The detection of the fluorescence signals, comprises two devices: The collector of the fluorescence photons of the tracers .The collection of the photons will be done by example with the aid of an object if turned towards the conveyor belt. This objective will collect and concentrate the light emitted by one or more particles at the detector input. Optical fibers may be used to collect and transport the fluorescence signals emitted by a particle to the detector (single fiber), or even the fluorescence signals emitted by several particles to the detector or detectors (multi-stranded fiber). A spectrometer type detector, which makes it possible to determine the wavelengths of the fluorescence signals of the tracers. It may consist of a rapid spectrometer commercially derived or optimally designed from different elements such as, for example, an inlet slit, a calibrated hole or a row of small diameter fibers. o A dispersive system for diffraction grating, prism, ... or Perot-Fabry type wavelengths, interference filters selected for the fluorescence wavelengths of the tracers o collimation optics and concentration of beams o Sensors of high sensitivity such as photodiode arrays (avalanche or not), CCD, EMCD or CMOS sensors, linear or two-dimensional, cooled or not, integrating or not selective filters (Bayer Matrix, IR filter, L RGB filter), microlens arrays, ... Linear CCDs are faster and can detect at integration times of 1ms. The data transfer times are generally 2u.s.

The detectors may also be photomultiplier tubes, avalanche photodiodes or any device capable of detecting and / or amplifying light signals of low intensities, equipped with Perot-Fabry type devices, interference filters selected for the lengths of light. fluorescence waves of tracers40 Illustration The following figure by way of example illustrates a hardware configuration adapted to the rapid detection of tracers on a conveyor The choice of tracers and their concentration are dependent on the detection system and the fluorescence of the polymers, the size of the particles and their speed on the conveyor. The laser beam is returned to the conveyor through a parabolic angled mirror and the laser signal scans the section of the conveyor. The fluorescence detection is in the visible but can be extended in the field of UV and Infrared. The detection system comprises a short-focus collimation system, for example 30 mm and diameter of for example 25 mm. The collimation system is 20 cm high compared to the conveyor. This optical part is connected to a spectrometer by means of an optical fiber. This system is repeated every 10 cm for example to detect the plastic particles that run on a conveyor from 50 to 100 cm for example. The detection of the polymer-tracer systems can also be done in free fall in this case the collimation system is located below the carpet and before the blow guns. Right-Angle Mirror Fiber Optic LASER UV Collimation System Crushed plastic plot rh = 200mm mm Spectro camera CCD - Conveyor 1-Tracer code detection 2- Polymer identification 3-Blow gun control for ejection of polymer traced for recycling Tests were carried out with a UV laser, Kimmon Model IK Series HeCd, an interference filter allowing the excitation wavelength specific to the signature of the tracers to pass. An optical ocean type spectrometer of type QE65000 or HR2000 + was used. The signal was detected using signal processing software.

The system configuration is optimal, ie the signal losses are less than 10%, if the incident laser beam or the collimation system is at an angle to the carpet normal lower than 30 ° (Figure 2 and 3).

Figure 2. Intensity of the fluorescence signal as a function of the angle of the laser relative to the normal to the conveyor Figure 3: Intensity in function collimator angle / normal The crushed plastics having thicknesses different between 1 mm and 4 mm thick, a variation of 3 mm, the short focal length of the collimation system can detect a variation of 3 mm with a signal loss of less than 10% (Figure 4). The following figure shows the fluorescence intensity of crushed plastics as a function of time. The steps are 10ms. Depending on the surface of the crushed plastics and the conveyor running time particles containing tracers can be detected. The wavelength corresponding to a fluorescence specific to each tracer serving as a signature to the plastic is indicated in the software as well as the beginning and the end of the wavelengths to be taken into account in calculating the area of the peak. A black is made to subtract the spurious noise due to any light pollution, a white is made to subtract the noise from the polymer matrix. The conveyor belt should be made of a material that does not have wavelength fluorescence for the detection of tracers and preferably plastics containing as much carbon black as possible or halogenated substances that absorb the fluorescence signals of the carrier. plastic carpet so as not to emit parasitic fluorescence. Residual fluorescence from the carpet can then be recorded and subtracted from the tracer signal.

The polymers are organic materials and have a high fluorescence which can hinder the detection of low concentrations of tracers. A favorable area has been determined. The excitation zone favorable to the detection of tracers is preferably less than 350 nm beyond which the polymers have a high fluorescence in the visible and the infrared. The detection zone favorable to fluorescence detection is preferably in the visible range between 400 nm and 750 nm. In fact, the fluorescence of the polymers is high. An indicator is calculated. If its value reaches a threshold defined by preliminary tests for a confidence interval greater than 95% then the signal is positive and the tracer is detected and the material identified. The threshold is determined by detecting the signal of materials without tracer and that of materials with tracer. The indicator may be the ratio of the peak area to an area corresponding to a non-tracer area. The advantage of the ratio method is to ignore the intensity of a signal that varies with the color of the material. Calculating a ratio is equivalent to normalizing all spectra.

Claims (1)

REVENDICATIONS1. Tests were carried out with 40mmx40mm particles with and without tracer. Plastics without tracers. The tracer has a peak between the wavelengths of 624 and 629nm, an indicator is calculated by making the ratio between the peak area and the area of a fluorescence zone of the stable and weak matrix. The threshold is 0.1 and corresponds to the noise. Only the signals of the plastics containing the tracer are detected with an indicator greater than 0.1 (Figures). The value of the indicator may depend on the size and the manner in which the particle appears in front of the detector for a speed of 3 m / s