System and method for detecting polymer materials from different raw material sources

Abstract

System (10) for detecting polymer materials from different raw material sources, comprising: - a flow generator (12), - a particle source (18), - a flow filter (14) for separating particles (32) of a non-fossil polymer material of different sizes and masses, - an inert gas source (20) for releasing an inert gas for transporting the particles (32), - a measuring device (70) for measuring the particle size and velocity of the particles transported in the inert gas (32), - a detection device (72) for determining the C12 and C13 values ​​of the particles (32), - an evaluation unit (74) for calculating a Delta-C13 value, wherein if a defined threshold value for the Delta-C13 value is undershot, a conclusion is drawn that the polymer material is non-fossil.

Description

The invention relates to a system for detecting polymer materials from different raw material sources and a method for detecting polymer materials from different raw material sources according to the preamble of the independent patent claims. The use of sustainable materials is an effective lever for improving the overall CO2 footprint of vehicles. Sustainable polymer solutions are therefore becoming increasingly important in the automotive industry. The three most relevant raw material sources for sustainable polymers include bio-based approaches based on renewable resources, recycled plastics, and CO2-based polymer approaches. A variety of bio-based polymers (PLA, PHB, etc.) are already known in the literature to keep the CO2 footprint low over the entire product life cycle compared to petrochemical alternatives. To reduce the overall CO2 footprint of vehicles, thermoplastic polymers from recycled processes are increasingly being required by law and used accordingly. This helps minimize additional CO2 emissions and greenhouse gas emissions through a closed material cycle.However, bio-based polymers and polymers from recycled processes are not suitable for every application, since both bio-based approaches and recycled plastics do not allow for control of the molecular weight and thus the physical, mechanical and chemical properties, due to natural synthesis processes on the one hand and degradation effects in the recycling process on the other. Thermoplastic polymers based on bound CO2 possess a specific property profile for the respective application due to a defined molecular weight and molecular weight distribution. Their greatest advantage over petrochemical polymer solutions is emissions reduction. CO2-based plastics are chemically identical to fossil-based plastics, which is why the separation of this class of materials from chemically identical material streams has not yet been possible. Current detection systems characterize the plastic fraction based on its chemical structure and physical properties, such as the density of the polymers. The raw material-dependent recycling of CO2-based plastics and bio-based polymers would offer significant advantages for the subsequent calculation of the carbon footprint within the context of an LCA in identifying the product's sustainability potential. This would allow the biogenic and CO2-based portion of the recyclate in the secondary material cycle to be mapped. Current detection systems (NIR, MIR, UV / VIS) cannot guarantee a distinction between bio-based PET, CO2-based PET, or petrochemical PET recyclate. The following processes for plastics separation in post-shredder processes of recycled plastics are known from the state of the art:- Infrared spectroscopy in the near or mid-infrared range (NIR, MIR),- Dry mechanical processing units: screening / classification, air separation / density separation,- Wet mechanical processing units: sink-float separation,- Black light + color sorting with image processing: Use of the reflection and fluorescence properties of the plastics (UV / VIS). However, none of these known processes is suitable for separating non-fossil and bio-based plastics from petrochemical plastics, since both the chemical and physical properties are identical. A "tracer-based sorting" approach is also known from the state of the art. In this approach, inorganic markers in the ppm range are applied to the plastics to be recycled. These markers are separated from the waste stream using fluorescence detection. However, this method significantly impacts the product manufacturing process, product costs, and the carbon footprint, as it requires an additional process step for introducing the markers, as well as prior synthesis of the markers. US Pat. No. 9,778,243 B2 discloses a method for measuring the carbon content of plastics made from renewable raw materials. The carbon content is measured by correlating the measured content of C13 isotopes (C13 value), measured by iTOC - CRDS and CM - CRDS, with the measured total carbon content (AMS or LSC 14C) using linear regression. WO 2010 / 005525 A1 discloses a method for detecting the content of C13 atoms in a polymer. This method can be used to distinguish petrochemically produced polymer materials from naturally produced rubber in polymer materials, particularly rubber-like polymer materials such as those used in tire production. From US 9 024 060 B2 a process for producing a plastic material based on renewable raw materials is known, whereby a distinction is made between plastic material based on renewable raw materials and a petrochemical raw material on the basis of the different number of C14 isotopes of the carbon compounds. The invention is based on the object of being able to distinguish non-fossil plastics from fossil plastics in a detection process and to overcome the disadvantages known from the prior art. The problem is solved by a system for detecting polymer materials from different raw material sources, which comprises a flow generator, a particle source, a flow filter for separating particles of a polymer material of different sizes and densities, and an inert gas source for releasing an inert gas to transport the particles. According to the invention, a measuring device for measuring a particle size and a particle velocity of the particles transported in the inert gas, a detection device for determining C12 and C13 values of the particles, and an evaluation unit for calculating a delta C13 value are also provided. If the delta C13 value falls below a defined threshold, a non-fossil polymer material is determined, and if the threshold value is exceeded, a fossil polymer material is determined. The delta-C13 value (also referred to as δ13C value in the literature) describes the isotopic ratio of the carbon isotopes 13C and 12C with respect to a standard and is defined by the following equation (1): In this context, a flow generator is understood to be a device that forms and / or directs and / or accelerates a gas flow. A flow generator can, in particular, comprise a pressure accumulator and a nozzle that delivers the gas stored in the pressure accumulator at a defined speed and direction, thereby providing a gas flow with a substantially constant velocity. Such a gas flow preferably has a gas velocity of 100 m / s to 250 m / s. A particle source is a device that supplies polymer particles to the detection process and can be introduced into such a gas stream. In particular, a grinder can be installed upstream of the particle source, which comminutes a polymer material into small particles, particularly as part of a recycling process. The comminuted particles, which can be fed into the gas stream via the particle source, are also referred to as plastic aerosol particles. In this context, a flow filter is a separation device that allows particles of a specific size and mass to pass through, particularly separating larger particles and / or particles with a higher mass. Separation is achieved primarily based on the inertia of the particles, so that only those particles that can follow the gas streamlines and are accelerated to the gas velocity, particularly to a velocity of 100 m / s to 250 m / s, pass through the flow filter. In this context, an inert gas source is a gas source that releases an inert gas. The inert gas source can be part of the flow generator or integrated into it. Inert gases include, in particular, the noble gases of the eighth main group of the periodic table of elements, with helium being particularly preferred. In this context, a measuring device is understood to mean any device suitable for determining the residence time (ToF) and the mass of the particles transported by the inert gas stream and not separated from the inert gas stream by the flow filter. Such a measuring device can, in particular, comprise an arrangement with two or more lasers, wherein the light scattering signals are measured, and the residence time (ToF) of the particles is deduced from the offset of the light scattering signals between the first laser and the second laser. From this, the mass of the particles can be determined. In this context, a detection device is understood to be a device with which the number of C12 and C13 isotopes of the carbon atoms in a polymer material can be quantitatively determined. Such a detection device can, in particular, comprise a mass spectrometer, with which the different isotopes of the carbon atoms can be detected in a known manner. In this context, an evaluation unit is understood to mean any type of device that enables the calculation of a delta-C13 value from the quantitative C12 and C13 values determined in the detection device and a comparison of this calculated delta-C13 value with a defined threshold value. The evaluation unit comprises, in particular, a computing unit that executes computer program code and, by means of the computer program code, enables an automated calculation and an automated comparison of the calculated delta-C13 value with the defined threshold values. The system according to the invention enables, particularly within the framework of a polymer recycling process, the differentiation of petrochemically produced polymer materials from polymer materials from different raw material sources. The system is particularly suitable for testing samples of recycled polymer materials inline during a recycling process and thus for characterizing the polymer materials and separating them according to their origin during recycling, especially after the plastics have been ground into small particles and before these particles are reused as starting materials for new primary forming processes. The features mentioned in the dependent claims enable advantageous improvements and further developments of the system mentioned in the independent claim for detecting polymer materials from different raw material sources. In a preferred embodiment of the invention, the flow filter comprises an aerodynamic lens. In this context, an aerodynamic lens is understood to be a device that, like an optical lens, has one or more apertures, so that a subset of the particles can be used for further processing through the aperture opening, while another subset, particularly larger or heavier particles, remain trapped at this aperture. This enables the separation of particles of the polymer material, allowing particles of a corresponding maximum particle size to be selected for analysis. It is particularly preferred that the aerodynamic lens comprises a tube and at least one aperture, preferably at least two, particularly preferably at least three apertures, for separating particles. A tube enables mixing of the particles with the inert gas stream from the system's gas source and acceleration of the particles to the gas velocity of the inert gas stream. The apertures can retain particles of different sizes or densities, thus enabling analysis of the particles of a defined maximum particle size of the polymer material transported by the inert gas stream and fed to the detection device. In an advantageous embodiment of the system for detecting polymer materials from different raw material sources, the measuring device for measuring particle size and particle velocity comprises a first laser and a second laser. Velocity can be easily measured using two lasers. The particle mass and velocity of the particles transported by the inert gas stream are determined from the scattering offset when a laser beam from the first laser and a laser beam from the second laser cross each other. This allows for precise determination of the particle velocity and particle size. According to a preferred embodiment of the system for detecting polymer materials from different raw material sources, the detection device comprises a mass spectrometer. A mass spectrometer can be used to determine the composition of the particles of the polymer material. In particular, a mass spectrometer enables differentiation between the different carbon isotopes of the particles, which allows conclusions to be drawn about the origin of the particles. Based on the proportion of C13 isotopes, it is possible to distinguish between fossil polymer materials and non-fossil polymer materials. In an advantageous embodiment of the system for detecting polymer materials from different raw material sources, the detection device comprises a first ion emitter, in particular a cation emitter, a second ion emitter, in particular an anion emitter, and a measuring laser. This enables excitation, evaporation, and ionization of the particles according to their energy levels. The ionized particles can then be analyzed using a suitable method, in particular mass spectrometry, and corresponding conclusions can be drawn about the origin of the particles. This enables a reliable and reproducible differentiation between fossil and non-fossil polymer materials. In a further improvement of the system for detecting polymer materials from different raw material sources, the detection device comprises a first reflector and a second reflector. The reflectors serve to keep the scattering particles within the measuring system, thus enabling reliable measurements. This can further improve the mass spectroscopy results. A further aspect of the invention relates to a method for detecting polymer materials from different raw material sources using such a system, which comprises the following steps:- providing particles of a polymer material,- providing a gas stream of an inert gas for transporting the particles,- separating particles of different sizes and masses,- measuring a particle mass and a particle velocity of the particles transported in the gas stream of the inert gas,- detecting C12 and C13 values of the particles,- calculating a delta-C13 value, and- comparing the calculated delta-C13 value with a defined threshold value for the delta-C13 value, wherein if the defined threshold value is undershot, a non-fossil polymer material is inferred, and if the defined threshold value of the delta-C13 value is exceeded, a fossil polymer material is inferred. Such a method makes it possible, for example, in a polymer recycling process, to distinguish petrochemically produced polymer materials from non-fossil polymer materials and to detect them according to their raw material source. The method is particularly suitable for testing samples of recycled polymer materials inline during a recycling process. This allows the polymer materials to be characterized during recycling, particularly after the plastics have been ground into small particles and before these particles are reused as starting materials for new primary forming processes, and to be detected and, if necessary, separated according to their origin. In an advantageous embodiment of the method, a delta-C13 value of less than 10‰ indicates a CO2-based polymer material, a delta-C13 value of 10‰ to 26‰ indicates a biogenic polymer material, and a delta-C13 value of greater than 26‰ indicates a fossil polymer material. In addition to distinguishing between a fossil polymer material and a non-fossil polymer material, such a method allows further differentiation between non-fossil polymer materials, allowing further conclusions to be drawn about their origin. This allows the recycled polymer materials to be tested for suitability for potential use in a new product. In an advantageous embodiment of the method, the particles are vaporized and ionized during detection using a measuring laser to determine the C12 and C13 values. Evaporation and ionization can break down the carbon compounds of a polymer material to subject the compounds to an analysis method, in particular mass spectrometry. The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless otherwise stated in the individual case. The invention is explained below in exemplary embodiments with reference to the accompanying drawings. Figure 1 shows a schematic representation of a preferred embodiment of a system according to the invention for detecting polymer materials from different raw material sources, and Figure 2 shows a flowchart for implementing a method according to the invention for detecting polymer materials from different raw material sources. Fig. 1 shows a system 10 for detecting polymer materials from different raw material sources. The system 10 comprises a flow generator 12, for example, a pressure tank for a gas with an outlet or a similar device for generating an inert gas stream. The flow generator 12 can, in particular, comprise one or more nozzles to accelerate and / or direct the inert gas stream. The system 10 further comprises a particle source 18, in particular a particle stream containing a comminuted polymer material, from which particles 32 of the polymer material can be fed to the inert gas stream. The system 10 further comprises a flow filter 14 for separating particles of a polymer material of different sizes and densities. The flow filter 14 can be designed, in particular as shown in Fig. 1, as an aerodynamic lens 16, which has a tube 24 for guiding an inert gas flow and at least one aperture 26, 28, 30 for separating particles 32 that, due to their size and / or weight, cannot follow the flow lines of the inert gas flow and are thus separated at an aperture 26, 28, 30. Fig. 1 shows an aerodynamic lens 16 with a first aperture 26, a second aperture 28, and a further aperture 30. The apertures 26, 28, 30 can have the same or different opening diameters.In particular, the apertures 26, 28, 30 can have decreasing opening diameters in the flow direction, so that the first aperture 26 has a comparatively large opening diameter, the second aperture 28 has a smaller opening diameter, and the further aperture 30 has an even smaller opening diameter. This allows for particularly efficient separation of particles 32 by the flow filter 14 in the form of the aerodynamic lens 16. Alternatively, the flow filter 14 can also be constructed in the manner of a cyclone separator, with heavier or larger particles 32 being separated from the inert gas stream in the cyclone separator due to their inertia. The system 10 further comprises an inert gas source 20 for releasing an inert gas for transporting the particles 32. The inert gas source 20 is designed, in particular, as a noble gas source 22 and can be integrated into the flow generator 12. Alternatively, the inert gas source 20 can also be connected upstream of the flow generator 12. In particular, the noble gases of the eighth main group of the Periodic Table of the Elements, particularly preferably helium, can be used as the inert gas. The inert gas from the inert gas source 20 forms a carrier gas 34 for transporting the particles 32 through the flow filter 14 and the components 70, 72 of the system 10 connected downstream of the flow filter 14. The system 10 further comprises a measuring device 70, in particular a measuring device 70 with a first laser 36 and a second laser 38, wherein the particles 32 in the inert gas stream are detected by the first laser 36 and with a time delay by the second laser 38, and a speed and a particle size of the particles 32 are deduced from the time delay and the scattering of the laser beams 40, 42 of the lasers 36, 38. The system 10 further comprises a detection device 72 for determining the C12 and C13 isotopes of the polymer materials. The detection device 72 is designed, in particular, as a mass spectrometer 48 and comprises a cation emitter 44, an anion emitter 46, and a measuring laser 50, with which the particles 32 are excited, vaporized, and ionized. The laser pulses of the lasers 36, 38 are superimposed to increase the measurement accuracy of the mass spectrometer 48 and to refine the resolution of the mass spectrometer 48. The detection device 72 further comprises a detector 52 for detecting the ions. The ions are analyzed according to their mass and classified by pattern recognition algorithms based on typical signatures. The detection device 72 may additionally comprise one or more reflectors 54, 56. The system 10 further comprises an evaluation unit 74 for calculating a delta C13 value. The evaluation unit 74 can, in particular, be integrated into a control unit 60, which comprises a memory unit 62 and a computing unit 64. Computer program code 66 is stored in the memory unit 62, which executes a method according to the invention for detecting polymer materials from different raw material sources when the computer program code 66 is executed by the computing unit 64 of the control unit 60. Fig. 2 shows a flow chart for a method according to the invention for detecting polymer materials from different raw material sources. In one process step <100> Particles 32 of a polymer material are provided. This can be done in particular by grinding a plastic intended for a recycling process. Preferably, the polymer material is comminuted into particles 32 with a particle size of less than 100 µm. In a further process step <110> a gas stream of an inert gas, preferably a helium gas stream, is provided for transporting the particles 32. In a process step <120> The particles 32 of different sizes and densities are separated by a flow filter 14, in particular by an aerodynamic lens 16. A classic aerodynamic lens 16 describes a tube 24 with a length of 10 cm to 30 cm, into which several apertures 26, 28, 30 are installed. If a particle 32 carried by a gas stream encounters such an aperture, the particle 32 is carried along by the streamlines of the carrier gas 34. If the particle 32 has a low mass and size, it can follow the streamlines. If the particle 32 has a high mass or is very large, it cannot follow the streamlines and, due to its inertia, is held against the walls of the aerodynamic lens 16 or one of the apertures 26, 28, 30. Particles 32 with the desired density and size are accelerated to a speed of 100 m / s to 250 m / s and then pass through two laser beams, during which the light scattering signals are measured. The offset between the two signals determines the time of flight (ToF).In one process step, this is <130> On the one hand, the particle size and, on the other hand, the arrival time of the particle 32 in the adjacent chamber (ion source) of a bipolar (anion and cation detecting) time-of-flight mass spectrometer 48 are determined. In the mass spectrometer 48, the particle 32 is precisely hit "in flight" by several special laser pulses in order to control the desired evaporation and ionization processes. The ions are <140> are analyzed according to their mass and classified by pattern recognition algorithms based on typical signatures and, if necessary, assigned to specific emission sources. This results in the typical C12 and C13 values, which are then calculated using equation (1) in a process step. <150> are put into a ratio from which a Delta-C13 value is determined.In one process step <160> The Delta-C13 value is compared with a defined threshold value, whereby if the value falls below the threshold value, a non-fossil origin of the polymer material is concluded, and if the threshold value is exceeded, a fossil origin of the polymer material is concluded. Typical delta-C13 values for non-fossil polymer materials are: - CO2 of the atmosphere: -8.00 ‰ - Corn (biogenic feedstock): -11.00 ‰ - Cane sugar (biogenic feedstock): -11.00 ‰ - PLA (biogenic feedstock): -14.00 ‰ - Cotton (biogenic feedstock): -23.00 ‰ - Natural rubber (biogenic feedstock): -25.00 ‰ - Cellulose (biogenic feedstock): -25.80 ‰ Typical Delta-C13 values for fossil polymer materials are: - Polyamide PA (petrochemical feedstock): -27.00 ‰ - Polypropylene PP (petrochemical feedstock): -28.50 ‰ Thus, the following breakdowns of materials can be derived: ▪ CO2-based plastics: > -10.00 ‰ ▪ Biogenic plastics: -10.00 ‰ to -26.00 ‰ ▪ Fossil plastics: < -26.00 ‰ Subsequent sorting of the raw material sources can be carried out in an air stream. The process technology of the invention demonstrated here can be scaled up to a larger scale, allowing the plastic samples to be characterized and separated inline during the recycling process. List of reference symbols 10 System for detecting polymer materials from different raw material sources 12 Flow generator 14 Flow filter 16 Aerodynamic lens 18 Particle source 20 Inert gas source 22 Noble gas source 24 Tube 26 First aperture 28 Second aperture 30 Additional aperture 32 Particles 34 Carrier gas 36 First laser 38 Second laser 40 First laser beam 42 Second laser beam 44 First ion beam (cation emitter) 46 Second ion beam (anion emitter) 48 Mass spectrometer 50 Measuring laser 52 Detector 54 First reflector 56 Second reflector 60 Control unit 62 Storage unit 64 Computing unit 66 Computer program code 70 Measuring device 72 Detection device 74 Evaluation unit QUOTES CONTAINED IN THE DESCRIPTION This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature US 9778243 B2

[0009] WO 2010005525 A1

[0010] US 9024060 B2

[0011]

Claims

System (10) for detecting polymer materials from different raw material sources, comprising:- a flow generator (12),- a particle source (18),- a flow filter (14) for separating particles (32) of a non-fossil polymer material of different sizes and masses,- an inert gas source (20) for releasing an inert gas for transporting the particles (32),- a measuring device (70) for measuring a particle size and a particle velocity of the particles (32) transported in the inert gas,- a detection device (72) for determining C12 and C13 values ​​of the particles (32),- an evaluation unit (74) for calculating a delta-C13 value, wherein a non-fossil polymer material is concluded if a defined threshold value for the delta-C13 value is undershot. System (10) for detecting polymer materials from different raw material sources according to claim 1, wherein the flow filter (14) comprises an aerodynamic lens (16). System (10) for detecting polymer materials from different raw material sources according to claim 1 or 2, wherein the measuring device (70) for measuring the particle size and the particle velocity comprises a first laser (36) and a second laser (38). System (10) for detecting polymer materials from different raw material sources according to one of claims 1 to 3, wherein the detection device (72) comprises a mass spectrometer (48). System (10) for detecting polymer materials from different raw material sources according to one of claims 1 to 4, wherein the detection device (72) comprises a first ion emitter (44), a second ion emitter (46) and a measuring laser (50). System (10) for detecting polymer materials from different raw material sources according to one of claims 1 to 5, wherein the detection device (72) comprises a first reflector (54) and a second reflector (56). System (10) for detecting polymer materials from different raw material sources according to claim 2, wherein the aerodynamic lens (16) has a tube (24) and at least one aperture (26, 28, 30) for separating particles. Method for detecting polymer materials from different raw material sources using a system (10) according to one of claims 1 to 7, comprising the following steps:- providing particles of a non-fossil polymer material (32),- providing a gas stream of an inert gas for transporting the particles (32),- separating particles (32) of different sizes and densities,- measuring a particle size and a particle velocity of the particles (32) transported in the gas stream of the inert gas,- detecting C12 and C13 values ​​of the particles (32),- calculating a delta-C13 value for the particles (32), and- comparing the calculated delta-C13 value with a defined threshold value for the delta-C13 value, wherein if the value falls below the defined threshold value, a non-fossil polymer material is inferred. Method for detecting polymer materials from different raw material sources according to claim 8, wherein a Delta-C13 value of:- < 10‰ indicates a CO2-based polymer material- 10‰ < Delta C13 < 26‰ indicates a biogenic polymer material, and- > 26‰ indicates a fossil polymer material. Method for detecting polymer materials from different raw material sources according to claim 8 or 9, wherein the particles are evaporated and ionized during detection by means of a measuring laser (50) in order to determine the C12 and C13 values.

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