Integrated analysis and optimization of mechanical recycling processes for polyolefins

Abstract

A process for collecting and storing quality control data in a polyolefin mechanical recycling process, a process for optimizing the performance of a polyolefin mechanical recycling process in response to said quality control data, a regulatory control model, and the use of the quality control data to optimize the performance of a polyolefin mechanical recycling process.

Description

[Technical field]

[0001] The present invention relates to a process for collecting and storing quality control data in a polyolefin mechanical recycling process, a process for optimizing the performance of a polyolefin mechanical recycling process in response to said quality control data, a regulatory control model, and the use of the quality control data to optimize the performance of a polyolefin mechanical recycling process. [Background technology]

[0002] Over the past decade, there has been an increased focus on the environmental sustainability of plastics and their current usage. This has led to the creation of new legislation regarding the disposal, recovery and recycling of polyolefins. Furthermore, many countries are making efforts to increase the recycling quotas for plastic materials instead of energy recovery / incineration or landfilling.

[0003] In Europe, plastic waste represents around 27 million tonnes of waste annually. Of this, in 2016, 7.4 million tonnes were disposed of in landfills, 11.27 million tonnes were burned (for energy production) and around 8.5 million tonnes were recycled. Polypropylene-based materials are particularly problematic due to the widespread use of these materials in packaging. Considering that the amount of waste collected is huge compared to the amount recycled back into the stream (only around 30%), there is still great potential for the intelligent reuse of plastic waste streams and for the mechanical recycling of plastic waste.

[0004] The present invention is particularly focused on mechanically recycled waste streams, rather than "energy recycling" in which polyolefins are burned and used for energy, or other forms of recycling such as chemical and solvent-based recycling. However, due to cost reasons, poor mechanical properties, and poor processing properties, waste streams containing crosslinked polyolefins are often used for energy recovery (e.g., incineration in district heating plants, or heat generation in the cement industry) and are rarely recycled into new products.

[0005] One of the main trends in the polyolefin sector is the use of recycled materials from various sources. Durable goods streams, such as those derived from waste electrical equipment (WEE) or end-of-life vehicles (ELV), contain a variety of plastics. These materials can be processed to recover acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), polypropylene (PP), and polyethylene (PE) plastics. Separation can be done using density separation in water, followed by further separation based on fluorescence, near-infrared absorption, or Raman spectroscopy.

[0006] The better the quality, i.e. the purer, the more expensive the material. Furthermore, recycled polyolefin materials are often cross-contaminated with non-polyolefin materials such as polyethylene terephthalate, polyamide, polystyrene, or non-polymeric substances such as wood, paper, glass, or aluminum.

[0007] In addition, materials containing high recycled olefins typically have much worse properties than virgin materials, unless the amount of recycled polyolefin added to the final formulation is extremely low.

[0008] Mechanical recycling processes for polyolefins typically include several component steps such as washing, shredding, screening, and possibly aeration, and optionally compounding / extrusion to form pellets of the recycled material. Each of these steps is typically used to improve one or more properties of the final recycled polyolefin. For example, screening can remove materials other than the desired polyolefin, and washing can remove contaminants from the surface of the article / flake.

[0009] Each of these component steps is generally used to target a specific problem, but none of them operates independently. For example, improved sorting may have the effect of reducing odors, an activity normally associated with washing and / or aeration steps. This additional benefit comes from avoiding any materials such as polystyrene or PVA that may degrade in later steps and contribute to the odor of the recycled polyolefins.

[0010] Thus, the interactions between the various components are more complex than many people realize.

[0011] In the art, the properties of recycled polyolefins are typically measured so that the recycled polyolefins may be sold or converted into suitable articles.

[0012] In recent years, some developments have been made in determining some very basic compositional characteristics of bales of material for recycling (i.e. polyolefin waste that will enter the mechanical recycling process of polyolefins), see for example EP 3465151 A1.

[0013] However, a much more complete characterization of the recycled stream during mechanical polyolefin recycling processes is not known. Such a system would allow a much greater understanding of the interactions between the individual constituent steps, reducing trial and error and allowing optimization of the entire recycling process. Furthermore, such a system would also allow quality control of the mechanical polyolefin recycling process, so that any defects in the recycled polyolefins could be quickly traced back to the poorly performing constituent steps, which could then be appropriately adjusted to eradicate the defects. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] European Patent Application Publication No. 3465151A1 Summary of the Invention [Means for solving the problem]

[0015] Accordingly, the present invention is directed to a process for collecting and storing quality control data of a polyolefin recycle stream at one or more intermediate locations in a polyolefin mechanical recycling process, said quality control data being any measurable mechanical, rheological or compositional one or more properties of the polyolefin(s) present in the polyolefin recycle stream, collected by a method selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis (TGA) of ash, dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry measurements, and combinations thereof.

[0016] In another embodiment, the present invention is directed to a process for optimizing the performance of a polyolefin mechanical recycling process comprising adjusting process conditions of one or more constituent steps within said polyolefin mechanical recycling process in response to quality control data measured on a polyolefin recycle stream at one or more intermediate locations in said polyolefin mechanical recycling process, said quality control data being any measurable mechanical, rheological or compositional one or more properties of the polyolefin(s) present in the polyolefin recycle stream, wherein optimizing the performance of said polyolefin mechanical recycling process is accompanied by an improvement in one or more mechanical, rheological and / or compositional properties of the recycled polyolefin composition.

[0017] The polyolefin mechanical recycling process of the present invention comprises, in the given order: a) providing a precursor mixed plastics recycle stream (A); b) sieving the precursor mixed plastics recycle stream (A) to create a sieved mixed plastics recycle stream (B) having only articles with a longest dimension in the range of 30-400 mm; c) sorting the sieved mixed plastics recycle stream (B) with one or more optical sorters to produce a monochromatic sorted polyolefin recycle stream (C), wherein the sieved mixed plastics recycle stream (B) is sorted at least by color, and optionally by polyolefin type and / or article form; d) reducing the size of the monochromatically separated pieces of the polyolefin recycle stream (C) to form a flake polyolefin recycle stream (D); e) washing the flake polyolefin recycle stream (D) with a first aqueous wash liquid (W1) without input of thermal energy to produce a first suspension polyolefin recycle stream (E); f) removing said first aqueous wash liquid (W1) from said first suspended polyolefin recycle stream (E) to obtain a first washed polyolefin recycle stream (F); g) washing the first washed polyolefin recycle stream (F) with a second aqueous wash liquid (W2) to produce a second suspended polyolefin recycle stream (G), wherein sufficient heat energy is input to the system during washing to raise the temperature to a range of 65-95°C; h) removing said second aqueous wash liquid (W2) and any material not floating on the surface of said second aqueous wash liquid from said second suspended polyolefin recycle stream (G) to obtain a second washed polyolefin recycle stream (H); i) drying said second washed polyolefin recycle stream (H) to obtain a dried polyolefin recycle stream (I); j) optionally separating the dried polyolefin recycle stream (I) into a light fraction and a heavy fraction polyolefin recycle stream (J); k) further screening the heavy fraction polyolefin recycle stream (J), or the dried polyolefin recycle stream (I) in the absence of step j), in one or more optical sorters to remove any flakes containing materials other than the polyolefin of interest to obtain a purified polyolefin recycle stream (K); l) optionally melt extruding and preferably pelletizing said purified polyolefin recycle stream (K) to form an extruded, preferably pelletized, recycled polyolefin product (L), wherein additives (Ad) are preferably added in the molten state; m) optionally aerating said recycled polyolefin product (L) or, in the absence of step l), said purified polyolefin recycle stream (K) to remove volatile organic compounds, thereby producing an aerated recycled polyolefin product (M), which is either an aerated extruded, preferably pelletized, recycled polyolefin product (M1) or an aerated recycled polyolefin flake (M2); wherein the purified polyolefin recycle stream (K) is first aerated to form the aerated recycled polyolefin flakes (M2) and then extruded, preferably by interchanging the order of steps l) and m) so that the additive (Ad) is added in the molten state to form an extruded, preferably pelletized, aerated recycled polyolefin product (M3), It is particularly preferred that the one or more intermediate positions of the recycle stream are selected from the group consisting of: between steps b) and c), between steps c) and d), between steps d) and e), between steps e) and f), between steps f) and g), between steps g) and h), between steps h) and i), between steps i) and j) if j) is present and between steps j) and k) or between steps i) and k) if j) is absent, as well as between steps k) and l), between steps k) and m), between steps l) and m) and between steps m) and l), when the respective steps are present.

[0018] In another embodiment, the present invention provides a computer-implemented method for providing training data for a regulatory control model configured to regulate process conditions of one or more constituent steps of a polyolefin mechanical recycling process based at least on measured quality control data in the method according to any one of the preceding claims, comprising: Providing quality control data for the method according to any one of the preceding claims; providing adjustment data corresponding to adjustments of the process conditions taking into account the provided quality control data; labeling said quality control data with said adjustment data; The present invention is directed to a method, comprising:

[0019] In a further embodiment, the present invention is directed to a regulatory control model at least trained with training data provided according to the computer-implemented method of the present invention.

[0020] The present invention is also directed to the use of a measurement method for obtaining quality control data at an intermediate point in a polyolefin mechanical recycling process, said measurement method being selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis of ash (TGA), dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry measurements, and combinations thereof, said quality control data being any measurable mechanical, rheological or compositional property or properties of the polyolefin(s) present in the polyolefin recycle stream that are measurable using said measurement method.

[0021] In a final embodiment, the present invention relates to the use of quality control data obtained at an intermediate location in a polyolefin mechanical recycling process for adjusting process conditions of one or more component steps within said polyolefin mechanical recycling process in order to optimize the performance of said polyolefin mechanical recycling process, comprising: said quality control data being any measurable mechanical, rheological or compositional property or properties of the polyolefin(s) present in the polyolefin recycle stream within said polyolefin mechanical recycling process; Optimizing the performance of the mechanical recycling process of the polyolefins is directed to uses involving improving one or more mechanical, rheological and / or compositional properties of the recycled polyolefin composition.

[0022] definition In the context of the present invention, a polyolefin recycling stream may be any stream in which polyolefins are present and suitable for recycling. This polyolefin may originate from post-consumer waste or industrial waste. Post-consumer waste refers to objects that have completed at least a first use cycle (or life cycle), i.e. have already fulfilled their first purpose, whereas industrial waste refers to manufacturing scrap, which usually does not reach the consumer.

[0023] The recycle stream may contain both articles to be recycled and pieces of articles to be recycled (referred to herein as flakes). In the context of the present invention, the contents of the recycle stream are referred to as pieces, whether they are whole articles, pieces thereof, or flakes thereof. In some embodiments, the pieces may be flakes, while in other embodiments, the pieces may be larger objects that may be converted to flakes at a later stage. In the context of the present invention, the terms "flake" and "flaky" are used to indicate that the polyolefin-containing pieces are not whole articles, but are broken down. This includes flakes of films (so-called two-dimensional flakes) and flakes of rigid articles (so-called three-dimensional flakes). Thus, in the context of the present invention, these terms should be interpreted as simply excluding the presence of whole articles in the recycle stream. Preferably, the flakes have a longest dimension in the range of 2-25 mm.

[0024] In the context of this invention, a mixed plastic recycle stream may be any stream suitable for recycling in which polyolefins are present and the stream does not contain only a single polyolefin product, as is the case, for example, in certain post-industrial recycle streams where a single polyolefin-containing article may be the only piece present in the stream, or in manufacturing waste streams where a single polyolefin-containing article may be the only piece present in the stream. Generally speaking, all polyolefin-containing post-consumer waste recycle streams will be mixed plastic recycle streams, as will many polyolefin-containing post-industrial recycle streams.

[0025] The term "article form" as used herein refers to the shape and form of the article present in the polyolefin recycling stream. Such articles may be present in the form of films, bags, and pouches, among others, which may be considered as flexible articles, or in the form of molded articles such as food containers, skin care product containers, plastic bottles, among others, which may be considered as rigid articles. Commercially available optical sorters such as Tomra Autosort, RTT Steinert Unisort, Redwave Pellenc, etc., can separate so-called rigid articles from so-called flexible articles by utilizing aerodynamic properties (i.e., a stream of gas is usually applied to the stream, and articles that are rigid articles fall in a different arc than flexible articles), and convert the stream containing such articles into so-called rigid streams and flexible streams.

[0026] According to an aspect of the present invention, a monochromatic sorted polyolefin stream (C) is obtained as an intermediate product as a result of the sorting process, which sorts polyolefin-containing articles at least according to their color. Those skilled in the art will recognize that a significant amount of polyolefin-containing articles in any given mixed-color recycle stream are transparent, i.e., colorless. For purposes of the present invention, any transparent, i.e., colorless, polyolefin-containing articles are considered to be a separate color classification, resulting in a monochromatic sorted polyolefin stream (C) whose "color" is colorless (i.e., transparent). In some embodiments, this colorless polyolefin recycle stream is passed through subsequent steps of the process to obtain a colorless recycle product, or in other embodiments, the colorless polyolefin recycle stream is mixed with a non-colorless monochromatic recycle stream (e.g., a white polyolefin recycle stream), and the mixed stream is considered a non-colorless monochromatic recycle stream (i.e., a mixture of the colorless stream and the white stream is then considered a white stream). Without wishing to be bound by theory, it is believed that the addition of colorless polyolefins to a non-colorless polyolefin recycle stream does not significantly affect the final color of the recycle product.

[0027] According to an embodiment of the invention, it is important that the monochromatically sorted recycle stream is subjected to the subsequent processing steps d) to m). In the context of the present invention, the term "monochromatic" should be interpreted as meaning substantially the same color, i.e. a polyolefin stream containing red pieces of various shades would be classified as a monochromatic stream, while a polyolefin stream containing red and yellow pieces would not be classified as a monochromatic stream. The precision of the monochromatic selection depends on the technology used for color sorting and is therefore limited by the available technology. Since the impression of color on the human eye cannot be strictly defined by wavelength, the definition on the CIELAB color scale is the most appropriate descriptor, considering that the same color may be obtained by a single wavelength of light or by a combination of different wavelengths. Particularly preferably, the same color means ΔE<50, preferably ΔE<40, more preferably ΔE<30, most preferably. ΔE is defined by the following formula:

number

[0028] Moreover, those skilled in the art will recognize that state of the art sorting methods, including automated sorting machines of the type discussed below, do not provide perfect sorting, which means that any phrases such as "the stream contains only a single color" or "the stream contains only a single polyolefin type" are to be interpreted broadly and that a stream so described contains substantially only the color or polyolefin type described, but is not 100% pure due to technical limitations of the sorting process.

[0029] Those skilled in the art will recognize that while pH values ​​greater than 14.0 and less than 0.0 are theoretically possible, it is very difficult to measure such pH values ​​using conventional pH probes. Thus, in the context of the present invention, an aqueous solution having an effective pH greater than 14.0 is considered to have a pH of 14.0, and an aqueous solution having an effective pH less than 0.0 is considered to have a pH of 0.0.

[0030] In the context of the present invention, the term "washing" is used to indicate the addition of a solvent, usually water, used to remove foreign matter or residual liquid from the polyolefin surface. This can be accomplished in a very short time, less than 5 minutes, often less than 1 minute, in contrast to "washing" steps, which usually require longer times and agitation to remove adherent foreign matter from the polyolefin surface and potentially extract volatile organic compounds from the polyolefin.

[0031] As will be clear to those skilled in the art, insofar as the present invention is directed to a process of collecting and storing quality control data, this term does not include processes in which data is measured, e.g., analyzed transiently in a sorting process, and immediately discarded. Processes are known in the art in which a polymer stream is sorted using one or more detection methods, such as IR spectroscopy, X-ray fluorescence (XRF), and laser spectroscopy, such as Raman spectroscopy, to classify each piece of polyolefin, and this classification is used to determine whether the piece is sorted into one stream or into a different stream. These processes are distinguished from those of the present invention by the feature of "storing quality control data", which allows complex analysis and optimization of the mechanical recycling process of polyolefins based on the stored quality control data.

[0032] When the term "comprising" is used in the present specification and claims, it does not exclude other unspecified elements of primary or secondary functional importance. For the purposes of the present invention, the term "consisting of" is considered to be a preferred embodiment of the term "comprising". Hereinafter, when a group is defined to include at least a certain number of elements, this is also understood to disclose a group that preferably consists only of these elements.

[0033] Where an indefinite or definite article is used when referring to a singular noun e.g. "a", "an" or "the", the plural of that noun is also included unless specifically stated otherwise. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In a first aspect, the present invention is directed to a process for collecting and storing quality control data of a polyolefin recycle stream at one or more intermediate locations of a polyolefin mechanical recycling process, the quality control data being any measurable mechanical, rheological or compositional one or more properties of the polyolefin(s) present in said polyolefin recycle stream collected by a method selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis of ash (TGA), dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry measurements, and combinations thereof.

[0035] In the context of the present invention, a mechanical polyolefin recycling process is any process that takes post-consumer or industrial waste and produces a recycled polyolefin composition. Typically, such processes involve a combination of many individual steps, such as washing, screening, aeration (ventilation), shredding, etc. In contrast to chemical recycling processes, mechanical polyolefin recycling processes do not involve chemical degradation of the polyolefin, but are simply mechanical reprocessing of polyolefins that have reached the end of their intended use. However, those skilled in the art will recognize that, as with any polymer processing process, polymer chains may be broken during the mechanical recycling process, resulting in minor degradation of the polymer. Those skilled in the art will understand that this minor degradation is not equivalent to the chemical degradation required for chemical recycling processes.

[0036] In its broadest sense, the present invention does not depend on the exact nature of the polyolefin mechanical recycling process, but rather on the existence of multiple component steps, as is typical of such polyolefin mechanical recycling processes.

[0037] Formally speaking, the first step in any mechanical process would be the provision of a polyolefin recycle stream, which is typically provided in the form of bales and may be collected and aggregated, or waste polyolefin bales may be purchased from various commercial companies.

[0038] This step is typically followed by several processing steps which may include, but are not limited to, size reduction, screening, washing, and aeration.

[0039] After these processing steps, the treated polyolefin may be provided in any form, however, typically the treated polyolefin is in flake form, which may be packaged and sold as flake recycled polyolefin, or may be compounded to form recycled polyolefin pellets and / or recycled polyolefin articles.

[0040] It is common in the art to measure the mechanical, rheological and compositional properties of the recycled polyolefins at the end of the polyolefin mechanical recycling process. This provides simple quality control data that can be used to evaluate the polyolefin mechanical recycling process. This characterization data is typically required to sell the recycled polyolefins.

[0041] However, measurements of the property(s) at intermediate points in the process are typically not performed.

[0042] In the context of the present invention, an intermediate position is any position other than the beginning (i.e., after providing waste polyolefin (i.e., polyolefin recycle stream) prior to the first processing step) or the end (i.e., the stage where recycled polyolefin (either in the form of flakes, pellets or articles) is obtained and ready for sale) of the polyolefin mechanical recycling process.

[0043] The measurement at the intermediate location may be between two of the constituent steps of the polyolefin mechanical recycling process, or may be performed during one of the constituent steps of the polyolefin mechanical recycling process by online determination of the relevant properties or by removing a sample from within the specific constituent step for offline testing. Depending on the nature of the constituent step, the collection of adequate quality control data during the constituent step may be quite difficult, and therefore it is preferred that the quality control data is obtained at an intermediate location between two of the constituent steps.

[0044] If the quality control data is obtained at an intervening location between one of the constituent steps, it is preferred that this step is not a sorting step. Thus, it is preferred that at least one of the one or more intermediate locations of the polyolefin mechanical recycling process is at an intermediate location other than during a sorting step, and more preferred that all of the one or more intermediate locations of the polyolefin mechanical recycling process are at intermediate locations other than during a sorting step.

[0045] According to the present invention, quality control data should be collected at one or more intermediate locations in the polyolefin mechanical recycling process, more preferably at two or more intermediate locations, more preferably at three or more intermediate locations, even more preferably at four or more intermediate locations, and most preferably at five or more intermediate locations.

[0046] In the broadest sense, the quality control data collected can be any mechanical, rheological or compositional property.

[0047] According to the first aspect of the invention, the quality control data should be collected by a method selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis of ash (TGA), dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry, and combinations thereof.

[0048] In addition to the above methods, further quality control data may be collected by melt flow rate measurements (MFR) and / or Fourier transform infrared spectroscopy (FT-IR).

[0049] While each of the measurement methods listed above provides direct evidence of a particular property of the polyolefins present in the polyolefin recycle stream (e.g., ash, volatile and semi-volatile content (VOC and FOG)), many methods can go beyond a simple check of a particular property and provide a deeper understanding of the composition of the polyolefin recycle stream.

[0050] However, in the context of this invention, quality control data simply refers to the directly measured properties that can be obtained via the measurement methods listed above, although the measured data can be used to infer other properties of the polyolefin recycle stream.

[0051] In a second aspect, the present invention is directed to a process for optimizing the performance of a polyolefin mechanical recycle process comprising adjusting process conditions of one or more constituent steps within the polyolefin mechanical recycle process in response to quality control data measured on the polyolefin recycle stream at one or more intermediate locations in the polyolefin mechanical recycle process, the quality control data being any measurable mechanical, rheological or compositional one or more properties of the polyolefin(s) present in the polyolefin recycle stream, wherein optimizing the performance of the polyolefin mechanical recycle process is directed to a process involving improvement of one or more mechanical, rheological and / or compositional properties of the recycled polyolefin composition.

[0052] A critical step in the process of the second embodiment is adjusting process conditions of one or more constituent steps within the polyolefin mechanical recycling process in response to quality control data measured on the polyolefin recycle stream at one or more intermediate locations in the polyolefin mechanical recycling process.

[0053] This quality control data is any measurable mechanical, rheological or compositional property or properties of the polyolefin(s) present in the polyolefin recycle stream.

[0054] In the second aspect, the quality control data is preferably collected by a method selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis of ash (TGA), dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry, and combinations thereof.

[0055] In addition to the above methods, further quality control data may be collected by melt flow rate measurements and / or Fourier transform infrared spectroscopy (FT-IR).

[0056] Each construction step (i.e., one or more construction steps) that is adjusted in the second embodiment may be either upstream or downstream from the intermediate location at which the quality control data measurement was performed. If multiple intermediate locations are used, the construction steps may be upstream of all the intermediate locations, downstream of all the intermediate locations, or upstream of some intermediate locations and downstream of other intermediate locations.

[0057] The terms upstream and downstream refer to the location of component steps with respect to the direction of flow of the polyolefin recycle stream through the mechanical recycling process.

[0058] In one embodiment of the second aspect, at least one of the one or more constituent steps of the step of adjusting process conditions of one or more constituent steps in a polyolefin mechanical recycling process is a constituent step upstream from the intermediate location where the quality control data was measured.

[0059] In this embodiment, perturbations in desired properties of the recycled polyolefin at the intermediate locations are determined, providing a method for evaluating prior construction steps that can be adjusted to fine-tune the properties of the polyolefin recycle stream at future intermediate locations.

[0060] In another embodiment of the second aspect, at least one of the one or more constituent steps of the step of adjusting process conditions of one or more constituent steps within a polyolefin mechanical recycling process is a constituent step downstream from the intermediate location at which the quality control data was measured.

[0061] In this embodiment, it is theoretically possible to adjust the properties of the polyolefin recycle stream to avoid the detected perturbation being present at the end of the recycle process.In other words, the defects observed in one of the upstream constituent steps in the mechanical recycle process of polyolefins can be compensated by adjusting the process conditions of one of the downstream constituent steps, thus avoiding a substandard recycled polyolefin product at the end of the process.

[0062] Each of these embodiments (upstream regulation and downstream regulation) can be used independently, or alternatively, both may be used together.

[0063] Some further embodiments are applicable to both the first and second aspects as described above.

[0064] In one embodiment, this process is a computer-implemented method.

[0065] In another embodiment, the measurement of the quality control data is performed online, meaning that the polyolefin whose properties are being measured is not removed from the recycling process.

[0066] In a further embodiment, the measurement of the quality control data is performed offline, meaning that the polyolefin whose properties are being measured is removed from the recycling process.

[0067] Whether quality control data measurements are performed on-line or off-line depends primarily on the nature of the measurement method being performed. Some measurements, such as IR spectroscopy, can be easily performed remotely without destroying the sample, whereas others, such as thermogravimetric analysis (TGA), headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), and temperature-modulated differential scanning calorimetry (TM-DSC), must be performed on samples removed from the process.

[0068] It is further preferred that the polyolefin measured in the recycle stream is in flake form.

[0069] Most component steps of mechanical recycling processes for polyolefins are improved by flaking the polyolefin, and therefore the polyolefin is typically in such form during and after such processes.

[0070] For some measurement methods, polyolefin needs to be further processed from the flake form present in the recycle stream, for example, freeze-ground.The requirement that the polyolefin measured in the recycle stream is flake does not exclude such further processing, but rather simply requires that the polyolefin is flake in the recycle stream.In the case of online measurement, this means that quality control data is measured on flakes.However, this does not necessarily apply in the case of offline measurement.

[0071] Although the polyolefin mechanical recycling process may be any collection of constituent steps known in the art, the polyolefin mechanical recycling process may include, in a given order: a) providing a precursor mixed plastics recycle stream (A); b) sieving the precursor mixed plastics recycle stream (A) to create a sieved mixed plastics recycle stream (B) having only articles with a longest dimension in the range of 30-400 mm; c) sorting the sieved mixed plastics recycle stream (B) with one or more optical sorters to produce a monochromatic sorted polyolefin recycle stream (C), wherein the sieved mixed plastics recycle stream (B) is sorted at least by color, and optionally by polyolefin type and / or article form; d) reducing the size of the monochromatically separated pieces of the polyolefin recycle stream (C) to form a flake polyolefin recycle stream (D); e) washing the flake polyolefin recycle stream (D) with a first aqueous wash liquid (W1) without input of thermal energy to produce a first suspension polyolefin recycle stream (E); f) removing said first aqueous wash liquid (W1) from said first suspended polyolefin recycle stream (E) to obtain a first washed polyolefin recycle stream (F); g) washing the first washed polyolefin recycle stream (F) with a second aqueous wash liquid (W2) to produce a second suspended polyolefin recycle stream (G), wherein sufficient thermal energy is input to the system during washing to raise the temperature to the range of 65-95°C; h) removing said second aqueous wash liquid (W2) and any material not floating on the surface of said second aqueous wash liquid from said second suspended polyolefin recycle stream (G) to obtain a second washed polyolefin recycle stream (H); i) drying said second washed polyolefin recycle stream (H) to obtain a dried polyolefin recycle stream (I); j) optionally separating the dried polyolefin recycle stream (I) into a light fraction and a heavy fraction polyolefin recycle stream (J); k) further screening the heavy fraction polyolefin recycle stream (J), or the dried polyolefin recycle stream (I) in the absence of step j), in one or more optical sorters to remove any flakes containing materials other than the polyolefin of interest to obtain a purified polyolefin recycle stream (K); l) optionally melt extruding and preferably pelletizing said purified polyolefin recycle stream (K) to form an extruded, preferably pelletized, recycled polyolefin product (L), wherein additives (Ad) are preferably added in the molten state; m) optionally aerating said recycled polyolefin product (L) or, in the absence of step l), said purified polyolefin recycle stream (K) to remove volatile organic compounds, thereby producing an aerated recycled polyolefin product (M), which is either an aerated extruded, preferably pelletized, recycled polyolefin product (M1) or an aerated recycled polyolefin flake (M2); wherein the purified polyolefin recycle stream (K) is first aerated to form the aerated recycled polyolefin flakes (M2) and then extruded, preferably by interchanging the order of steps l) and m) so that the additive (Ad) is added in the molten state to form an extruded, preferably pelletized, aerated recycled polyolefin product (M3), It is particularly preferred that the one or more intermediate positions of the recycle stream are selected from the group consisting of: between steps b) and c), between steps c) and d), between steps d) and e), between steps e) and f), between steps f) and g), between steps g) and h), between steps h) and i), between steps i) and j) if j) is present and between steps j) and k) or between steps i) and k) if j) is absent, as well as between steps k) and l), between steps k) and m), between steps l) and m) and between steps m) and l), when the corresponding steps are present.

[0072] Particularly preferred intermediate positions in the abovementioned mechanical recycling processes for polyolefins include between steps c) and d), between steps d) and e), between steps f) and g), between steps i) and j) if j) is present and between steps j) and k) or between steps i) and k) if j) is not present, as well as between steps k) and l), between steps k) and m), between steps l) and m) and between steps m) and l), when the corresponding steps are present.

[0073] The above polyolefin mechanical recycling process is described in detail in European Patent Application No. 21216996.5. All alternatives and preferred embodiments disclosed therein for the polyolefin mechanical recycling process are applicable, mutatis mutandis, to the polyolefin mechanical recycling process of the above embodiment.

[0074] Step a) involves providing a precursor mixed plastics recycle stream (A).

[0075] This precursor mixed plastics recycle stream (A) may be derived from post-consumer, post-industrial, or a combination thereof.

[0076] Step b) involves sieving the precursor mixed plastics recycle stream (A) to create a sieved mixed plastics recycle stream (B) having only articles with their longest dimension in the range of 30-400 mm.

[0077] Those skilled in the art will recognize that there are multiple ways that the sieving in step b) can be achieved, and therefore this sieving step is not particularly limited.However, preferably, the sieving in step b) is achieved by using a sieve with a sieve diameter of 30 mm and a sieve with a sieve diameter of 400 mm to divide the precursor mixed recycling stream into three streams, namely a small item stream with a longest dimension of less than 30 mm, an oversized item stream with a longest dimension of more than 400 mm, and a sieved mixed plastic recycling stream (B).The small item stream and the oversized stream can be discarded or transferred to be used in other polyolefin mechanical recycling processes.

[0078] Step c) involves sorting the sieved mixed plastics recycle stream (B) with one or more optical sorters to produce a single-color sorted polyolefin recycle stream (C), where the sieved mixed plastics recycle stream (B) is sorted at least by color, and optionally also by polyolefin type and / or article form.

[0079] The articles separated from the monochromatically sorted polyolefin recycle stream (C) may be discarded or transferred to a further iteration of step c) directed to another monochromatically sorted polyolefin recycle stream.

[0080] Preferably, the sorting in step c) is carried out by color, type of polyolefin and type of article, which means that the monochromatically sorted polyolefin recycle stream (C) is monochromatic, all articles contain a single polyolefin and the stream contains only rigid or flexible articles.

[0081] Although the process of the present invention is suitable for isolating any desired polyolefin from a mixed polyolefin recycle stream, isolation of polyethylene or polypropylene is particularly desirable since these are likely to be the major polyolefin components of any mixed polyolefin recycle stream and the isolated polyethylene or isolated polypropylene can be fed to a pure recycled polyolefin stream or extruded and pelletized to obtain pellets of the desired polyolefin, i.e., polyethylene or polypropylene.

[0082] Particularly preferably, the monochromatically separated polyolefin recycle stream (C) is either a monochromatically separated polyethylene recycle stream or a monochromatically separated polypropylene recycle stream.

[0083] Step d) involves reducing the size of pieces of the monochromatically sorted polyolefin recycle stream (C) to form a flake polyolefin recycle stream (D).

[0084] The size reduction in step d) may be carried out by any method known to the person skilled in the art, for example by grinding or shredding the monochromatically sorted polyolefin recycle stream (C).

[0085] Step e) involves washing the flaked polyolefin recycle stream (D) with a first aqueous wash liquid (W1) without input of thermal energy to produce a first suspended polyolefin recycle stream (E).

[0086] Those skilled in the art will recognize that cleaning steps known in the art may be heated to achieve high temperature cleaning or may be carried out at ambient conditions to achieve low temperature cleaning. In the present method, step e) represents such a low temperature cleaning.

[0087] Step f) involves removing the first aqueous wash liquid (W1) from the first suspended polyolefin recycle stream (E) to obtain a first washed polyolefin recycle stream (F).

[0088] The skilled person will understand that small amounts of foreign matter suspended or dissolved in the first suspended polyolefin recycle stream (E) are removed in the first aqueous wash liquid (W1), but step f) does not involve targeted removal of foreign matter, for example by use of so-called sink-float separation, in this case with 0.1% or more of the foreign matter (with a density of 1.00 g / cm 3 It will be appreciated that any foreign matter that does not float to the surface of the solution (considering that less than 1000 g of polyolefin is expected to float) will be removed with the solution.

[0089] Step g) involves washing the first washed polyolefin recycle stream (F) with a second aqueous wash liquid (W2) to produce a second suspended polyolefin recycle stream (G), where sufficient heat energy is input into the system to raise the temperature during washing to the range of 65-95°C.

[0090] As previously mentioned, one skilled in the art will recognize that cleaning steps known in the art may be heated to achieve a high temperature cleaning or may be carried out at ambient conditions to achieve a low temperature cleaning. The cleaning step g) is a high temperature cleaning in contrast to the cleaning step e), in which thermal energy is input to ensure a temperature of 65-95°C during cleaning.

[0091] The temperature in step g) is in the range of 65 to 95°C, more preferably in the range of 70 to 95°C, and most preferably in the range of 75 to 95°C.

[0092] Preferably, the second aqueous washing liquid (W2) is an alkaline aqueous washing liquid.

[0093] In a particularly preferred embodiment, the second aqueous cleaning liquid (W2) is a sodium hydroxide solution having a sodium hydroxide concentration in the range of 0.50 to 5.0% by weight, based on the total weight of the second aqueous cleaning liquid (W2).

[0094] Step h) involves removing the second aqueous wash liquid (W2) and any material that does not float on the surface of the second aqueous wash liquid from the second suspended polyolefin recycle stream (G) to obtain a second washed polyolefin recycle stream (H).

[0095] In contrast to step f), in which only small amounts of foreign matter suspended or dissolved in the washing liquid are removed, step h) involves a so-called sink-float separation, whereby all materials that do not float on the surface of the washing liquid are removed. 3 It will be appreciated that the effect of this is to remove any foreign matter having a density greater than 100 nm.

[0096] Step i) involves drying the second washed polyolefin recycle stream (H) to obtain a dried polyolefin recycle stream (I).

[0097] The drying in step i) can be achieved by thermal drying or by a combination of mechanical and thermal drying. Suitable forms of mechanical drying include centrifugal drying and dewatering presses (filters or screw presses), both of which are capable of separating liquids from solids.

[0098] Step j), if present, involves separating the dried polyolefin recycle stream (I) into a light fraction and a heavy fraction polyolefin recycle stream (J).

[0099] The light fraction typically contains labels and other non-polyolefin materials, while polyolefin flakes are sorted into the heavy fraction polyolefin recycle stream (J).

[0100] The separation in step j) can be carried out by any known dry state density separation technique known in the art. Suitable techniques include air classification, air sieving, zigzag cascade or air separation.

[0101] Step k) involves further sorting the heavy fraction polyolefin recycle stream (J), or the dried polyolefin recycle stream (I) in the absence of step j), in one or more optical sorters to remove any flakes containing materials other than the polyolefin of interest, to obtain a purified polyolefin recycle stream (K).

[0102] In step k), at least a first optical sorter is used to remove flakes containing materials other than the polyolefin of interest. The selection criteria of this optical sorter is such that if any material other than the polyolefin of interest is present in a given flake, this flake is separated from the stream and a purified polyolefin recycle stream is obtained. Multiple optical sorters with the same selection criteria may be placed in series to improve the purity of the purified polyolefin recycle stream (K).

[0103] Step l) involves melt extruding and preferably pelletizing the purified polyolefin recycle stream (K), if present, to form an extruded, preferably pelletized, recycled polyolefin product (L), wherein additives (Ad) are preferably added in the molten state.

[0104] Step m) involves aerating the recycled polyolefin product (L), if present, or the purified polyolefin recycle stream (K), if step l) is not present, to remove volatile organic compounds to produce an aerated recycled polyolefin product (M), which is either an aerated extruded, preferably pelletized, recycled polyolefin product (M1) or an aerated recycled polyolefin flake (M2).

[0105] The aeration in step m) may be achieved by the use of air, an inert gas, or steam, among others.

[0106] More preferably, the process further includes providing an adjustment control model configured to adjust process conditions of one or more constituent steps based at least on the measured quality control data.

[0107] Such a control model is preferably based on the results of a machine learning algorithm, the term machine learning algorithm having to be understood broadly and preferably including decision trees, naive Bayes classification, nearest neighbor, neural networks, convolutional neural networks, generative adversarial networks, support vector machines, linear regression, logistic regression, random forests and / or gradient boosting algorithms. Preferably, the machine learning algorithm is organized to process inputs with high dimensionality into outputs with much lower dimensionality. Such machine learning algorithms are called "intelligent" because they can be "trained". The algorithm may be trained using a record of training data. The record of training data includes training input data and corresponding training output data. The training output data of the record of training data are the results expected to be produced by the machine learning algorithm when given the training input data of the same record of training data as input. The deviation between this expected result and the actual result produced by the algorithm is observed and graded by a "loss function". This loss function is used as feedback to adjust the parameters of the internal processing chain of the machine learning algorithm. For example, parameters may be tuned with an optimization objective that minimizes the value of a loss function that results when all training input data is fed into a machine learning algorithm and the results are compared to the corresponding training output data. The result of this training is that, given a relatively small number of training data records as "ground truth," the machine learning algorithm can perform its job well on a number of input data records that are several orders of magnitude higher.

[0108] In particular, the above-mentioned methods / processes may be executed by computer program elements. The computer program elements may be stored in a computing unit of a computing device that may also be part of the embodiments. The computing unit may be configured to execute or trigger the execution of the steps of the above-mentioned methods. Furthermore, the computing unit may be configured to operate the components of the above-mentioned system. The computing unit may be configured to operate automatically and / or to execute user orders. The computing unit may include a data processor. The computer program may be loaded into the working memory of the data processor. The data processor may thus be equipped to execute the method according to one of the above-mentioned embodiments. This exemplary embodiment of the present disclosure covers both computer programs that use the present disclosure from the beginning and computer programs that, by updating, transform an existing program into a program that uses the present disclosure. Furthermore, the computer program elements may be capable of providing all the steps necessary to carry out the procedures of the above-mentioned exemplary embodiments of the methods. According to a further exemplary embodiment of the present disclosure, a computer readable medium such as a CD-ROM, a USB drive, a downloadable executable file, etc. is presented, on which the computer readable medium is stored the computer program elements described by the previous section. The computer program may be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless communication systems. However, the computer program may also be presented over a network, such as the World Wide Web, and may be downloaded from such a network into the working memory of a data processor.According to a further exemplary embodiment of the present disclosure, a medium is provided for making available for download a computer program element configured to perform a method according to one of the above-mentioned embodiments of the present disclosure.

[0109] In another embodiment, the present invention provides a computer-implemented method for providing training data for a regulatory control model configured to regulate process conditions of one or more constituent steps of a polyolefin mechanical recycling process based at least on measured quality control data in the method according to any one of the preceding claims, comprising: Providing quality control data for the method of the preceding claims; providing adjustment data corresponding to adjustments of process conditions taking into account the provided quality control data; labelling said quality control data with said adjustment data; The present invention is directed to a method, comprising:

[0110] The present invention is further directed to a regulatory control model that is at least trained with training data provided by the computer-implemented method described above.

[0111] In another aspect, the present invention is directed to the use of a measurement method for obtaining quality control data at an intermediate point of a polyolefin mechanical recycling process, the measurement method being selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis of ash (TGA), dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry measurements, and combinations thereof, wherein said quality control data is any measurable mechanical, rheological or compositional property or properties of the polyolefin(s) present in the polyolefin recycle stream that are measurable using said measurement method.

[0112] In a final aspect, the present invention relates to the use of quality control data obtained at intermediate locations in a polyolefin mechanical recycling process for adjusting process conditions of one or more component steps within said polyolefin mechanical recycling process in order to optimize the performance of said polyolefin mechanical recycling process, comprising: This quality control data is any measurable mechanical, rheological or compositional property or properties of the polyolefin(s) present in the polyolefin recycle stream within the polyolefin mechanical recycling process; Optimizing the performance of this polyolefin mechanical recycling process involves improving one or more mechanical, rheological and / or compositional properties of the recycled polyolefin composition for use.

[0113] All preferred and alternative embodiments of the process for storing quality control data and for optimizing the performance of a polyolefin mechanical recycling process as described above are applicable, mutatis mutandis, to the use of the measurement methods and the use of the quality control data described above. EXAMPLES

[0114] Measurement method Flake Subsampling To obtain a representative test portion for subsequent analysis, a coning and quartering approach was applied, performed according to DIN / EN 15002:2015. Within this approach, the flake sample is thoroughly mixed, spread on a flat surface and formed into a cone. The sample is then quartered with a metal cloth to obtain four slices with the same shape and size. Two opposite quarters are discarded and the remaining two are thoroughly mixed. For each coning and quartering cycle, the sample amount is divided into two equal parts. The previously described steps (mixing, cone formation, quartering and discarding) were repeated until the required sample amount of about 120 g was obtained (e.g., for an initial sample amount of 1 kg, three cycles are required).

[0115] Flake sample preparation After subsampling, the flakes are freeze-ground using a centrifugal mill ZM200 and a 1.0 mm sieve. The resulting freeze-ground material (approximately 120 g) is dried in an air-circulating oven at 80° C. for 3 h for the following subsequent tests: MFR, frequency sweep, LAOS, DSC, FTIR, density, HPLC antioxidants (AO) and GC additives. For HS / GC / MS (HS incubation 100° C. / 2 h), no drying is performed. The flake samples for HS / GC / MS analysis were immediately packed into aluminum bags to properly seal and preserve the odor components.

[0116] Additive analysis by HPLC The additive analysis was carried out using freeze-ground and dried flakes. The metal net approach was applied for both additive methods (HPLC antioxidants and GC additives). Information on the applied procedures and test setup is given in Table 1.

[0117] [Table 1]

[0118] HS-GC-MS analysis This analysis is used to indirectly estimate the odor relevance of selected marker substances. The determination is based on a static headspace (HS) approach. This in-house custom analysis uses an HS / GC / MS instrument for relative comparison of peak areas. This approach is used for screening purposes only due to its measurement principle. True quantification of the amount of substance in the polyolefin matrix is ​​not applicable.

[0119] 2.000±0.050 g of frozen ground flakes or frozen ground pellets were weighed into 20 ml HS vials and sealed with PTFE caps. Duplicate measurements were performed for all samples.

[0120] The specific HS / GC / MS test parameters applied in these studies are described below. HS parameters (Agilent G1888 headspace sampler) Vial equilibration time: 5 min (standard), 120 min (sample) Oven temperature: 200℃ (standard), 100℃ (sample) Loop temperature: 205℃ Transfer line temperature: 210℃ low shaking GC parameters (Agilent 7890A GC system) Column: ZB- WAX 7HG-G007-22 (30m x 250μm x 1μm) Carrier gas: Helium 5.0 Flow rate: 2ml / min Split: 5:1 GC oven program: 35°C, 0.1 min. 10°C / min up to 250°C 250℃ 1 minute MS parameters (Agilent 5975C inert XL MSD) Acquisition mode: Scan Scan parameters: Low mass: 20 High mass:200 Threshold: 10 Software / Data Evaluation MSD ChemStation E.02.02.1431 MassHunter GC / MS Acquisition B.07.05.2479 AMDIS GC / MS Analysis Version 2.71 NIST / EPA / NIH Mass Spectral Library (2011 version) NIST Mass Spectral Search Program Version 2.0 g

[0121] The information on the standard solutions used is as follows: Standards with defined marker substances were prepared for positive identification and comparison using the (lowest) Odor Detection Threshold (ODT) (see Table II). For standard 1, methanol was used as the solvent and for standard 2, 2-butanol was used. For HS / GC / MS analysis, 5 μl of each standard was injected into separate 20 ml HS vials, sealed with PTFE caps, and measured. At a given HS parameter, it can be assumed that all standards are completely vaporized. G The concentrations of each analyte in are listed in Table 2.

[0122] [Table 2]

[0123] For data evaluation, the following principles are considered: Headspace C G The concentration of the analyte in G and the available headspace volume V G It can be determined by considering (Equation 1).

number

number

number

[0124] FT-IR spectroscopy Standard transmission FTIR measurements were performed on compression molded plaques made from the freeze-ground flakes according to the procedure described below. A minimum of three compression molded samples are tested to ensure representativeness. The polyolefin and non-polyolefin compositions are determined semi-quantitatively or quantitatively depending on the material.

[0125] Sample preparation: All calibration samples and samples to be analyzed are prepared in a similar way on melt-press plates made from freeze-ground powder (flakes). Approximately 2-3 g of the formulation to be analyzed are melted at 190 ° C. Subsequently, a pressure of 60-80 bar is applied for 20 seconds in a hydraulic heating press. The sample is then cooled to room temperature in 40 seconds in a cold press under the same pressure in order to control the morphology of the formulation. The thickness of the plate is controlled by a metal calibration frame plate 2.5 cm x 2.5 cm, 100-200 μm thick (depending on the MFR from the sample). Two plates are produced in parallel at the same moment and under the same conditions. The thickness of each plate is measured before the FTIR measurement. All plates are 100-200 μm thick. To control the plate surface and to avoid interference during the measurement, all plates are pressed between two double-sided silicone release papers. For powder samples or heterogeneous blends, the pressing process is repeated three times to increase homogeneity by pressing and cutting the samples under the same conditions as above.

[0126] Spectrometer: A standard transmission FTIR spectrometer, such as a Bruker Vertex 70 FTIR spectrometer, is used with the following settings: 4000~400cm -1 The spectral range of 6mm aperture, 2cm -1 The spectral resolution of 16 background scans, 16 spectral scans, ·Interferogram zero-filling factor of 32 ·Norton Beer Strong Apodization. Spectra are recorded and analyzed with Bruker Opus software.

[0127] Calibration samples: Since FTIR is a secondary method, several calibration standards were formulated to cover the target analytical range. Typically, - 0.2% to 2.5% by weight for PA For PS, 0.1% to 5.0% by weight 0.2% to 2.5% by weight for PET - 0.1% to 4.0% by weight for PVC It is. The following commercially available materials were used in the formulations: Borealis HC600TF as iPP, Borealis FB3450 as HDPE, and RAMAPET N1S (Indorama Polymer) for PET, Ultramid® B36LN (BASF) for polyamide 6, Styrolution PS 486N (Ineos) for high impact polystyrene (HIPS), and Inovyn PVC 263B (in powder form) for PVC were used as target polymers. All formulations are prepared on a small scale in a Haake kneader at temperatures below 265° C. for less than 10 minutes to avoid decomposition. Additional antioxidants such as Irgafos 168 (3000 ppm) are added to minimize degradation.

[0128] calibration: The FTIR calibration principle is the same for all components. The intensity of a particular FTIR band divided by the plate thickness is the 1 H or 13 C correlates with the amounts of components determined by solution-state NMR. Each specific FTIR absorption band is selected by its increase in intensity with the amount of component concentration and by its separation from the rest of the peaks, regardless of the composition of the calibration standards and the actual sample. This method is described in the publication by Signoret et al., "Alterations of plastic in MIR and the potential impacts on identification towards recycling," Resources, conservation and Recycling journal, 2020, Volume 161, Article 104980. The wavelengths of each calibration band are as follows: For PA, it is 3300cm -1 , 1601cm for PS -1 , 1410 cm for PET -1 , 615cm for PVC -1 , 1167 cm for iPP -1 . For each polymer component i, construct a linear calibration (based on the linearity of the Beer-Lambert law). A typical linear correlation used for such a calibration is shown below:

number

[0129] No specific separation band could be found for the C2-rich fraction, so the C2-rich fraction was indirectly estimated.

number

[0130] Temperature Modulated Differential Scanning Calorimetry Temperature modulated differential scanning calorimetry (TM-DSC) experiments were carried out on a TA Instruments Q2000 instrument calibrated with indium, zinc and tin according to ISO11357 / 1. Measurements were carried out on 5±1 mg samples under nitrogen atmosphere (50 mL / min) in a heating / cooling / heating cycle between -30°C and 225°C at a scan rate of 10°C / min, for the first heating run and the cooling run according to ISO11357 / 3. The second heating run was carried out in a controlled manner, specifically with a temperature regulation of 0.32°C every 60 seconds, while heating the sample at 2°C / min. The irreversible heat flow was specifically analyzed. The relative content of PE in the recycled material was quantified by integration between 50°C and 140°C, where each detected peak was further attributed to a different PE fraction. In particular, the integral as the "perpendicular drop" to 115°C characterizes the LDPE content in the blend.

[0131] Ash by TGA Thermogravimetric analysis (TGA) experiments were performed using a Perkin Elmer TGA8000. Approximately 10-20 mg of material was placed in a platinum pan. The temperature was equilibrated at 50°C for 10 min and then ramped to 950°C at 20°C / min under nitrogen. Ash content was assessed as wt% at 850°C.

[0132] MFR (Melt Flow Rate) The melt flow rate (MFR) is determined in accordance with ISO 1133 - Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics -- Part 1: Standard method and is expressed in g / 10 min. MFR is an indicator of the flowability and therefore processability of a polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR2 of polypropylene is determined at a temperature of 230°C and a load of 2.16 kg. The MFR2 of polyethylene is determined at a temperature of 190°C and a load of 2.16 kg. Measurements were performed on freeze-ground flakes.

[0133] Frequency sweep (dynamic rheology) measurements Characterization of polymer melts by dynamic shear measurements follows ISO standards 6721-1 and 6721-10. Measurements were performed on an Anton Paar MCR501 stress-controlled rotational rheometer equipped with a 25 mm parallel plate geometry. Measurements were performed on compression molded plates using a nitrogen atmosphere and strain settings within the linear viscoelastic range. Oscillatory shear tests were performed at 190 °C and 200 °C for PE and PP, respectively, applying a frequency range of 0.01 to 600 rad / s and setting a gap of 1.3 mm. In dynamic shear experiments, the probe is subjected to uniform deformation with a sinusoidally varying shear strain or shear stress (strain and stress controlled modes, respectively). In controlled strain experiments, the probe is subjected to a sinusoidal strain that can be expressed as: γ(t)=γ0sin(ωt) (1) If the applied strain is within the linear viscoelastic region, the resulting sinusoidal stress response can be given by: σ(t)=σ0sin(ωt+δ) (2) During the ceremony, σ0 and γ0 are the stress and strain amplitudes, respectively. ω is the angular frequency, δ is the phase difference (loss angle between the applied strain and the stress response), where t is time.

[0134] Dynamic test results are typically expressed in terms of several different rheological functions: the shear storage modulus G', the shear loss modulus G", the complex shear modulus G * , complex shear viscosity η *, the dynamic shear viscosity η', the heterophase component of the complex shear viscosity η", and the loss tangent tan δ, and the rheological function can be expressed as follows:

number

[0135] The determination of the so-called Shear Thinning Factor (STF) is carried out as described in Equation 13.

number

number

[0136] The value is determined by a single-point interpolation procedure defined by the Rheoplus software. * In situations where the values ​​are not reached experimentally, the values ​​are determined by extrapolation, using the same procedure as before. In both cases (interpolation or extrapolation), the option "- Interpolate y-values ​​to x-values ​​from parameter" and "logarithmic interpolation type" from Rheoplus was applied. These tests were performed on compression molded discs made using the freeze-milled powder.

[0137] LAOS (Strain Sweep, Dynamic Rheology) The study of nonlinear viscoelastic behavior under shear flow was carried out by means of large amplitude oscillatory shear. This method requires the application of a sinusoidal strain amplitude γ0 imposed at a given angular frequency ω for a given time t. If the applied sinusoidal strain is high enough, a nonlinear response is generated. In this case, the stress σ is a function of the applied strain amplitude, time and angular frequency. Under these conditions, the nonlinear stress response is still a periodic function. However, it can no longer be represented by a single harmonic sinusoid. The stress [0~0] resulting from the nonlinear viscoelastic response can be represented by a Fourier series including harmonic contributions.

number

[0138] The nonlinear viscoelastic response was analyzed by applying Large Amplitude Oscillatory Shear (LAOS) [4-6]. Time sweep measurements were performed on an Alpha Technologies RPA2000 rheometer coupled with a standard biconical die. The test chamber is sealed and a pressure of approximately 6 MPa is applied during the course of the measurements. LAOS tests are performed at a temperature of 190 °C, an angular frequency of 0.628 rad / s, and a strain of 1000% is applied. To ensure that steady-state conditions are reached, the nonlinear response is determined only after at least 20 cycles per measurement are completed. The Large Amplitude Oscillatory Shear Non-Linear Factor (LAOS_NLF) is:

number

[0139] These tests were performed on freeze-milled powders.

[0140] [1] J. M. Dealy, K. F. Issbrun, Melt Rheology and Its Role in Plastics Processing: Theory and Applications; edited by Van Nostrand Reinhold, New York (1990) [2] S. Filipe, Non-Linear Rheology of Polymer Melts, AIP Conference Proceedings 1152, pp. 168-174 (2009) [3] M. Wilhelm, Macromol. Mat. Eng. 287, 83-105 (2002) [4] S. Filipe, K. Hofstadler, K. Klimke, ATTran, Non-Linear Rheological Parameters for Characterization of Molecular Structural Properties in Polyolefins, Proceedings of Annual European Rheology Conference, 135(2010) [5] S. Filipe, K. Klimke, A.T.Tran, J. Reussner, Proceedings of Novel Non-Linear Rheological Parameters for Molecular Structural Characterisation of Polyolefins, Novel Trends in Rheology IV, Zlin, Czech Republic (2011) [6] K. Klimke, S. Filipe, ATTran, Non-linear rheological parameters for characterization of molecular structural properties in polyolefins, Proceedings of European Polymer Conference, Granada, Spain (2011)

[0141] Uniaxial extensional viscosity, SER Uniaxial extensional viscosity was measured from uniaxial extensional flow measurements performed on an Anton Paar MCR501 coupled to a Sentmanat extensional fixture (SER-1).

number

[0142] XRF The instrument used for the XRF measurements was a wavelength dispersive device called Zetium (2.4 kW) manufactured by Malvern Panalytical. The instrument was calibrated with a set of polyolefin-based standards from Malvern Panalytical. The method is used to determine the quantitative content of F, Na, Mg, Al, Si, P, S, Ca, Ti, Zn, Cr, Cd, Hg, Pb, As, Ni, Cu, Ba, Br, Cl, Sb, Sn in a polyolefin matrix within the specified range of these standards. The analysis is carried out under vacuum on plates with a diameter of 40 mm and a thickness of 2 mm. Elements not covered by the standards or whose content is outside the calibrated standard range are then analyzed in semi-quantitative mode (Omnian). The semi-quantitative mode covers the elements Be-U.

[0143] The samples tested included compression molded discs made from freeze-milled powder.

[0144] CIELAB This method is used to measure the color of the flakes and follows ISO 11664-4. A spectrophotometer is used to measure three standard color values ​​X, Y and Z and then compare them with the CIE L * , a * , b * and used to calculate the color distance.

[0145] Laser spectroscopy (e.g., Raman spectroscopy) Laser spectroscopy is a general term for different spectroscopic techniques that involve the interaction of a laser beam with matter, in particular Raman spectroscopy, vibrational spectroscopy of chemicals, absorption spectroscopy involving quantum cascade lasers (QCLs) in the IR spectral region, and laser-induced breakdown spectroscopy (LIBS), in which a laser vaporizes a material and detects the emitted light from the resulting plasma.

[0146] Laser / Raman spectrometers are well known in the art, and it is not critical which of the many commercially available spectrometers is used in the context of the present invention. Moreover, the person skilled in the art can appropriately determine the exact experimental setup based on known procedures, depending on exactly which property is to be measured.

Claims

1. 1. A method for collecting and storing quality control data of a polyolefin recycle stream at one or more intermediate locations in a polyolefin mechanical recycling process, wherein the quality control data is any measurable mechanical, rheological or compositional one or more properties of polyolefins present in the polyolefin recycle stream collected by a method selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis (TGA) of ash, dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectroscopy, and combinations thereof.

2. 2. The method of claim 1, wherein the quality control data is collected at two or more intermediate locations in the polyolefin mechanical recycling process, more preferably at three or more intermediate locations, even more preferably at four or more intermediate locations, and most preferably at five or more intermediate locations.

3. 3. The method according to claim 1 or claim 2, wherein at least one of the one or more intermediate positions of the mechanical recycling process of the polyolefins is at an intermediate position other than during a sorting step, and more preferably all of the one or more intermediate positions of the mechanical recycling process of the polyolefins is at an intermediate position other than during a sorting step.

4. 1. A method of optimizing the performance of a polyolefin mechanical recycling process comprising adjusting process conditions of one or more constituent steps within the polyolefin mechanical recycling process in response to quality control data measured on a polyolefin recycle stream at one or more intermediate locations in the polyolefin mechanical recycling process, wherein the quality control data is any measurable mechanical, rheological or compositional one or more properties of polyolefins present in the polyolefin recycle stream, and wherein optimizing the performance of the polyolefin mechanical recycling process involves improving one or more mechanical, rheological and / or compositional properties of a recycled polyolefin composition.

5. 5. The method of claim 4, wherein at least one of the one or more constituent steps in the step of adjusting process conditions of one or more constituent steps within the polyolefin mechanical recycling process is a constituent step upstream from the intermediate location where the quality control data was measured.

6. 6. The method of claim 4 or claim 5, wherein at least one of the one or more constituent steps of the step of adjusting process conditions of one or more constituent steps within the polyolefin mechanical recycling process is a constituent step downstream from the intermediate location where the quality control data was measured.

7. 7. The method of any one of claims 1 to 6, wherein the polyolefin being measured in the recycle stream is in flake form.

8. The method according to any one of claims 1 to 7, wherein the measurement of quality control data is performed online.

9. The method according to any one of claims 1 to 8, wherein the measurement of quality control data is performed offline.

10. The mechanical recycling process of said polyolefins comprises, in a given order: a) providing a precursor mixed plastics recycle stream (A); b) sieving said precursor mixed plastics recycle stream (A) to create a sieved mixed plastics recycle stream (B) having only articles with a longest dimension in the range of 30-400 mm; c) sorting the sieved mixed plastics recycle stream (B) with one or more optical sorters to produce a monochromatically sorted polyolefins recycle stream (C), wherein the sieved mixed plastics recycle stream (B) is sorted at least by color, and optionally by polyolefin type and / or article form; d) reducing the size of the monochromatically separated pieces of the polyolefin recycle stream (C) to form a flake polyolefin recycle stream (D); e) washing the flake polyolefin recycle stream (D) with a first aqueous wash liquid (W1) without input of thermal energy to produce a first suspension polyolefin recycle stream (E); f) removing said first aqueous wash liquid (W1) from said first suspended polyolefin recycle stream (E) to obtain a first washed polyolefin recycle stream (F); g) washing the first washed polyolefin recycle stream (F) with a second aqueous wash liquid (W2) to produce a second suspended polyolefin recycle stream (G), wherein sufficient thermal energy is input into the system during washing to raise the temperature to the range of 65-95°C; h) removing said second aqueous wash liquid (W2) and any material not floating on the surface of said second aqueous wash liquid from said second suspended polyolefin recycle stream (G) to obtain a second washed polyolefin recycle stream (H); i) drying said second washed polyolefin recycle stream (H) to obtain a dried polyolefin recycle stream (I); j) optionally separating the dried polyolefin recycle stream (I) into a light fraction and a heavy fraction polyolefin recycle stream (J); k) further screening the heavy fraction polyolefin recycle stream (J), or the dried polyolefin recycle stream (I) in the absence of step j), in one or more optical sorters to remove any flakes containing materials other than the polyolefin of interest to obtain a purified polyolefin recycle stream (K); l) melt extruding and preferably pelletizing said optionally purified polyolefin recycle stream (K) to form an extruded, preferably pelletized, recycled polyolefin product (L), wherein additives (Ad) are preferably added in the molten state; m) optionally aerating said recycled polyolefin product (L) or, in the absence of step l), said purified polyolefin recycle stream (K) to remove volatile organic compounds, thereby producing an aerated recycled polyolefin product (M), which is either an aerated extruded, preferably pelletized, recycled polyolefin product (M1) or an aerated recycled polyolefin flake (M2); wherein the purified polyolefin recycle stream (K) is first aerated to form the aerated recycled polyolefin flake (M2) and then extruded, preferably by interchanging the order of steps l) and m) so that the additive (Ad) is added in the molten state to form an extruded, preferably pelletized, aerated recycled polyolefin product (M3), 10. The method of any one of claims 1 to 9, wherein the one or more intermediate positions of the recycle stream are selected from the group consisting of: between steps b) and c), between steps c) and d), between steps d) and e), between steps e) and f), between steps f) and g), between steps g) and h), between steps h) and i), between steps i) and j) if j) is present and between steps j) and k), or between steps i) and k) if j) is absent, and between steps k) and l), between steps k) and m), between steps l) and m), and between steps m) and l), when the respective steps are present.

11. 11. The method of claim 1, further comprising providing an adjustment control model configured to adjust process conditions of the one or more component steps based at least on the measured quality control data.

12. 12. A computer-implemented method for providing training data for a regulatory control model configured to regulate process conditions of one or more constituent steps of a mechanical recycling process for polyolefins based at least on measured quality control data of the method according to any one of claims 1 to 11, comprising: Providing quality control data for the method of any one of claims 1 to 11; providing adjustment data corresponding to adjustments of the process conditions taking into account the provided quality control data; labeling said quality control data with said adjustment data; A method comprising:

13. A regulatory control model at least trained with training data provided according to claim 12.

14. 1. Use of a measurement method for obtaining quality control data at an intermediate point in a polyolefin mechanical recycling process, said measurement method being selected from the group consisting of headspace-gas chromatography-mass spectrometry (HS-GC-MS), high performance liquid chromatography (HPLC), temperature modulated differential scanning calorimetry (TM-DSC), thermogravimetric analysis of ash (TGA), dynamic rheology measurements by frequency sweep analysis, large amplitude oscillatory shear (LAOS) measurements, uniaxial extensional flow measurements (SER), X-ray fluorescence measurements (XRF), laser spectroscopy such as Raman spectroscopy, CIELAB spectrophotometry measurements, and combinations thereof, and said quality control data being any measurable mechanical, rheological or compositional property or properties of polyolefins present in a polyolefin recycle stream that are measurable using said measurement method.

15. 1. Use of quality control data obtained at an intermediate location in a polyolefin mechanical recycling process to adjust process conditions of one or more component steps within said polyolefin mechanical recycling process in order to optimize the performance of said polyolefin mechanical recycling process, comprising: said quality control data being any measurable mechanical, rheological or compositional property or properties of polyolefins present in a polyolefin recycle stream within said polyolefin mechanical recycling process; Optimizing the performance of the mechanical recycling process of said polyolefins involves improving one or more mechanical, rheological and / or compositional properties of the recycled polyolefin composition.

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