Plastic waste recycling process

Abstract

The present invention provides a plastic waste recycling process including extracting polyolefins from polymer-containing waste material comprising the steps of A) providing polymer-containing waste material comprising polyolefin material, B) contacting the polymer-containing waste material with a non-polar solvent, preferably comprising at least one optionally substituted hydrocarbon, such as optionally halogenated hydrocarbon, to form a composition, C) heating the composition at a dissolution temperature (T) in the range of from 135 to 200 °C and a pressure (P) in the range of from 0.1 to 5 MPa abs. for a period of from 5 min to 5 h (M), to obtain a first solution comprising the non-polar solvent and polyolefin material dissolved in the non-polar solvent, and an undissolved solid material, D) separating the undissolved solid material from the first solution, E1) contacting the first solution with a polar solvent having a Hansen solubility parameter for hydrogen bonds (δh) within the range of 4 to 15 MPa0.5, preferably a polar aprotic solvent having a Hansen solubility parameter for hydrogen bonds (δh) within the range of 4 to 15 MPa0.5, the polar solvent being used in an amount within the range of from 1 to 50 vol.-% relative to the volume of the first solution, and extracting polymeric non-polyolefin material into the polar solvent, thereby obtaining a liquid / liquid phase system comprising (i) a second solution comprising the non-polar solvent and polyolefin material dissolved in the non-polar solvent, and (ii) a third solution comprising the polar solvent and polymeric non-polyolefin material dissolved in the polar solvent, E2) separating the third solution from the second solution, wherein the sequences of steps E1) and E2) can be performed before or after step D), F) removing the non-polar solvent from the second solution to obtain polyolefin material in solid form, and G) further treating the polyolefin material obtained in step F) in a chemical recycling process.

Description

[0001] Plastic waste recycling process

[0002] The present invention generally relates to a plastic waste recycling process including extracting polyolefins from polymer-containing waste material and further treating the polyolefins in a chemical recycling process. The present invention further relates to liquefied or gasified plastic waste obtainable by the process.

[0003] Background

[0004] The challenge of the disposal of accumulated waste plastics and corresponding environmental issues have received widespread attention from the public and professionals. Therefore, besides the concepts of the prevention of plastic waste in general and the prevention of leakage of plastic waste into the environment in particular, recycling of waste plastics material has become an important topic. Waste plastics can be turned into resources for new plastic products. Hence, environmental and economic aspects can be combined in recycling and reusing waste plastics material. Since the mid-90s, several European countries have begun to implement waste collection systems, which allow more target orientated collection and separation of plastic materials from other waste materials. These systems enable a broad separation of polymer types from each other. In parallel, several plastic recycling processes have been developed, in particular aiming on the increase of product quality of the recyclable polymer materials.

[0005] There are different routes of plastic recycling commonly known including mechanical recycling (i.e. material sorting), advanced physical or solvent based recycling and chemical processing (e.g. thermochemical recycling such as pyrolysis or gasification). Among these methods, mechanical recycling and chemical recycling are the most widely practiced.

[0006] Nowadays, advanced mechanical recycling includes separation steps such as shredding, vibrating, rotary sieving, advanced sorting methods supported by spectrometric-methods [e.g. NIR / VIS] and wash operations to reduce organic, biologic and partly odor contaminants primary from the surface of the recyclable plastic material, as well as achieving a polymer type enriched and more homogeneous polymer recyclate fraction (e.g. of 85 to 95 wt.% of a respective polymer type). However, the product quality remains relatively poor and does not allow for both food contact and use in high performance applications.

[0007] The second plastic recycling route is chemical recycling, also referred to as thermochemical processing. This route provides a promising opportunity to recover pre-sorted and pre-treated solid plastic waste to obtain feedstocks for the petrochemical industry, which may be processed to plastics again, as well as to chemical commodities and fuels. To degrade the polymeric structure of the plastic solid mixture to shorter hydrocarbons up to monomeric building blocks, significant amount of heat has to be applied. Thus, the main drawbacks are the energy-consuming thermal degradation together with CO2-emission.

[0008] Pyrolysis is an important technique for chemically recycling e.g. plastic waste. The pyrolysis is generally a thermal degradation of feedstock in an inert atmosphere and yields value added products such as pyrolysis gas, liquid pyrolysis oil and char (residue), wherein pyrolysis oil containing hydrocarbons is the major product.

[0009] Dependent on the type and quality of feedstock used for the preparation of pyrolysis oil, a broad range of impurities can typically be found in the pyrolysis oil. Typical feedstock for the preparation of pyrolysis oil is plastic waste, but also biomass may be used. Pyrolysis oil produced from plastic waste contains more and other contaminants than fossil feedstock whereas plastics are used for a wide variety of applications and therefore contains a wide variety of different additives. Such impurities found in the pyrolysis oil are for example inorganic compounds, such as metal-containing compounds and complexes, and organic compounds containing heteroatoms, such as nitrogen, oxygen, sulphur, silicon, and halogens, particularly chlorine. The pyrolysis oil might also have generally higher content of unsaturated hydrocarbon compounds, such as olefins, than fossil feedstock. Low concentrations of these impurities, particularly chlorine-containing compounds and diolefins, is for instance of high importance for avoiding problems during storage and processing of the pyrolysis oil, including for use as (steam) cracker feedstock in base chemical production such as ethylene and propylene. Otherwise, the impurities can lead to problems in the further processing or use of the pyrolysis oil, such as sedimentation and gum formation, deactivation / poisoning of catalysts, formation of deposits and corrosion of lines and reactors. Steam cracking of untreated plastic waste pyrolysis oils is for example discussed by Kusenberg et al, “Assessing the feasibility of chemical recycling via steam cracking of untreated plastic waste pyrolysis oils: Feedstock impurities, product yields and coke formation”, Waste Management, vol 141, pages 104-114 (2022), where the authors conclude that purification of the pyrolysis oil prior to steam cracking is a prerequisite to avoid operational issues resulting from increased coke formation and fouling.

[0010] In accordance with Kusenberg et al, “Opportunities and challenges for the application of post-consumer plastic waste pyrolysis oil as steam cracker feedstock: To decontaminate or not to decontaminate?”, Waste Management, vol. 148, pages 83-115 (2022), a typical steam cracker feedstock for base chemical production may include not more than 3 ppm chlorine, not more than 100 ppm nitrogen, and not more than 100 ppm oxygen.

[0011] For being able to meet the high purity standards that are required for the use of these pyrolysis oils, for example as steam cracker feedstock for base chemical production, typically dilution with fossil naphtha and / or purification of the pyrolysis oil is required. Purification of crude pyrolysis oil can for example be done by a costly hydrotreatment step or simply by a washing step, i.e. by extracting the impurities with a solvent that is immiscible with the oil. However, even if such a washing step can be efficient for the removal of polar impurities, only a low removal efficiency can be found in case of non-polar impurities with a high solubility in the oil, e.g. certain organic chlorides.

[0012] Generally, pyrolysis oil at least partially originating from the pyrolysis of plastic waste requires dehalogenation (particularly dechlorination), denitrogenation and deoxygenation to reduce the concentrations of these impurities and allow use in cracker feedstock, such as steam cracker feedstock.

[0013] The third plastic recycling route is advanced physical or “Solvent based Recycling” (SbR). In SbR-processing the polymer is initially dissolved in an appropriate solvent and next either the solubility of the dissolved polymer is decreased by the addition of a non-solvent (dissolution / precipitation) and / or solidification of the polymer is caused by the preferably complete separation of the solvent from the solidified polymer by thermal unit operations (evaporation, drying etc.). The main advantages of SbR-processing can be found in the preservation of the original molecular structure and the mostly relevant properties, density and MFR, for re-processing (compounding, conversion), and in the possibility to separate polymer additives, e.g. fillers, stabilizers, antioxidants and / or pigments, to gain a virgin-like high-quality polyolefin, which can be finally adjusted to the desired polyolefin grade by compounding.

[0014] Mechanical recycling is seen as the preferred recycling technology in terms of sustainability, in particular the CO2 footprint. Consequently, chemical recycling shall be applied only when mechanical recycling is not technically and economically viable or leads to low-quality products or has a higher negative environmental impact. This so-called cascading utilization of plastic waste feedstock means that chemical recycling shall be seen as complimentary to mechanical recycling. As a result, plastic waste feedstock for chemical recycling, especially, but not exclusively limited to pyrolysis, is of considerably worse quality than material intended for mechanical recycling.

[0015] In contrast to mechanical recycling the feedstock for chemical recycling may have a significantly lower polyolefin (PO) content.

[0016] For multilayer material packaging, these are often comprised of films that are coloured, printed, metallized and consist of often complex multilayer structures, such as PE / PA, PE / PET with EVOH as barrier layer, which are often laminated with e.g. Pll, epoxy resins, MuF-, MF-resins. The waste streams often contain relevant amount of polymeric non-polyolefin material like PS, ABS, PVC, PA, PET and nitrile rubber. Furthermore, non-plastic contaminations or non-polymer material, such as glass, metals, paper, stones, rubber, textiles, cartons, residual food / cosmetics, may also be present.

[0017] While the described polymeric non-polyolefin material and other contaminations hinder the mechanical recycling, they also pose a significant barrier for current chemical recycling technologies: For available chemical recycling technologies on the market, the tolerable amount of polymeric non-polyolefin material content is rather small. Non-PO plastics have a negative impact on the pyrolysis process making it challenging and sometimes not achievable.

[0018] Thus, currently the only way to use waste streams with high contents of non-PO polymers is pyrolyzing them “as-is”. For many pyrolysis technologies this may not be possible, especially concerning for the case that hetero-atomic- (N / O / S) or halides-containing non-PO plastic types are fed to the pyrolysis reactor, also in low concentrations due to formation of heteroatomic aromatics, acids and polycyclic aromatic compounds. Principally, a hydrotreating of the obtained “low quality” pyrolysis oil is principally technical possible, but remarkable expensive and operative-intensive (HP, excess on H2 necessary), so that the hydrotreated pyrolysis oil gets suitable for blending with fossil-based naphtha for steam cracking afterwards.

[0019] Description of the invention

[0020] Thus, it is an object of the present invention to provide a plastic waste recycling process including extraction of polyolefins from waste sources for further use in chemical recycling, such as pyrolysis.

[0021] It is a further object of the invention to provide a plastic waste recycling process including extraction of polyolefins from waste streams with high levels of polymeric non-polyolefin compounds, such as polyamide (PA), polyethylene terephthalate (PET), polyurethane (Pll) etc. It is still a further object of the invention to provide a plastic waste recycling process enabling extraction of polyolefins from multilayer packaging materials and further use thereof in chemical recycling.

[0022] The present invention is based on the surprising finding that polyolefins can be efficiently extracted from waste samples by dissolution at specific conditions. By a particular order of steps, different classes of polyolefins may be extracted in high purity grades.

[0023] Therefore, the present invention provides a plastic waste recycling process comprising the steps of:

[0024] A) providing polymer-containing waste material comprising polyolefin material,

[0025] B) contacting the polymer-containing waste material with a non-polar solvent, preferably comprising at least one optionally substituted hydrocarbon, such as optionally halogenated hydrocarbon, to form a composition,

[0026] C) heating the composition at a dissolution temperature (T) in the range of from 135 to 200 °C and a pressure (P) in the range of from 0.1 to 5 MPa abs. for a period of from 5 min to 5 h (M), to obtain a first solution comprising the nonpolar solvent and polyolefin material dissolved in the non-polar solvent, and an undissolved solid material,

[0027] D) separating the undissolved solid material from the first solution,

[0028] E1) contacting the first solution with a polar solvent having a Hansen solubility parameter for hydrogen bonds (5h) within the range of 4 to 15 MPa0 5, preferably a polar aprotic solvent having a Hansen solubility parameter for hydrogen bonds (5h) within the range of 4 to 15 MPa0 5, the polar solvent being used in an amount within the range of from 1 to 50 vol.-% relative to the volume of the first solution, and extracting polymeric non-polyolefin material into the polar solvent, thereby obtaining a liquid / liquid phase system comprising (i) a second solution comprising the non-polar solvent and polyolefin material dissolved in the nonpolar solvent, and (ii) a third solution comprising the polar solvent and polymeric non-polyolefin material dissolved in the polar solvent,

[0029] E2) separating the third solution from the second solution,

[0030] wherein the sequences of steps E1) and E2) can be performed before or after step D),

[0031] F) removing the non-polar solvent from the second solution to obtain polyolefin material in solid form; and

[0032] G) further treating the polyolefin material obtained in step F) in a chemical recycling process.

[0033] Generally, within the meaning of the present invention, unless otherwise indicated, the percentages are weight percentages (wt.%), usually based on the total weight of the respective entity.

[0034] Further, it should be understood within the meaning of the present invention that the below-described embodiments may be combined.

[0035] The present invention offers various advantages. The invention allows waste streams with high levels of polymeric non-polyolefin compounds, such as polyamide (PA), polyethylene terephthalate (PET), polyurethane (Pll) etc., stemming from multilayer packaging to be processed in subsequent pyrolysis by removing the respective polymers prior to the pyrolysis. As a result, the polyolefin (PO) content of that multilayer packaging can be fully recycled by chemical recy-cl ing / pyrolysis while at the same removing the non-recyclable polymeric non-PO components. For example, for polyethylene / polyamide (PE / PA) multilayers a typical PE content is about 80 wt.% which can be recycled.

[0036] This has the further advantage that a subsequent chemical recycling process of step G), such as a pyrolysis process, can be run with a higher purity stream (higher PO content), and thus improving the overall yield. Accordingly, the need for a subsequent purification of the pyrolysis oil is significantly reduced. In addition, waste streams with high levels of PA, PET, Pll, etc. are also processible and the invention thus provides a circular solution for multilayer packaging materials comprising PO.

[0037] The present invention is beneficial for the purpose of purifying waste streams for chemical recycling, and in particular pyrolysis.

[0038] The present invention is also able to enrich PO from agglomerates of plastics mixtures which cannot be further purified by NIR-sorting or density separation. By the process according to the present invention, polyolefins are extracted from polymer-containing waste material by dissolving the polyolefins from the poly-mer-containing waste material. Preferably, polyolefins are separated in a first sequence of the process steps comprising steps A) to F), which may be the only steps of the process.

[0039] The process according to the invention may be operated as a continuous or discontinuous process. In one embodiment, the process is operated as a discontinuous process, preferably wherein the separation step D) and / or the contacting step B) are performed as steps of a batch process.

[0040] In another embodiment, the process is operated as a continuous process, i.e. a flow process without interruption, wherein the separation step D) and / or the contacting step B) are performed directly and without interruption. In a preferred embodiment, the non-polar solvent obtained in step F) is continuously refed to step B) without interruption.

[0041] In still another embodiment, the steps A) to F) of the process disclosed herein are performed as a continuous process providing a polyolefin material which then for example may be stored prior to performing the chemical recycling of step G) of the process as disclosed herein.

[0042] In step A) of the process according to the invention, the polymer-containing waste material preferably comprises from 35 to 90 wt.% of polyolefin material, based on the total weight of the polymer-containing waste material. More preferably, the polymer-containing waste material comprises from 40 to 70 wt.% and most preferably from 45 to 65 wt.% of polyolefin material, based on the total weight of the polymer-containing waste material. Polymer material in the meaning of the invention refers to a material comprising polymers, i.e. large molecules with molecular weights ranging from a few thousand to as high as millions of g / mol and being composed of many repeating units. Usually, the polymer-containing waste material comprises different types of polymer material. Generally, the polymer material comprises at least one polyolefin (PO) material comprising at least one polyolefin component, preferably, the polyolefin material comprises at least two, more preferably at least three and often up to 20 polyolefin (PO) components. Polyolefin (component) in the meaning of the invention refers to polyethylene and / or polypropylene, in particular comprising homopolymers and copolymers of ethylene and propylene, respectively.

[0043] Polyethylene in the meaning of the present invention refers to an ethylene homopolymer and an ethylene copolymer having at least 50 mol%, preferably at least 70 mol% and most preferably at least 90 mol% and up to less than 100 mol% of ethylene units. Other units, preferably other alpha-olefin units, may be contained in the polyethylene. Similarly, polypropylene in the meaning of the present invention refers to a propylene homopolymer and propylene copolymer having at least 50 mol%, preferably at least 70 mol% and most preferably at least 90 mol% and up to less than 100 mol% of propylene units.

[0044] Preferably, the polymer material of the polymer-containing waste material further comprises at least one polymer material, preferably a polymeric non-polyolefin material, selected from the group consisting of polystyrene (PS) material, polyethylene terephthalate (PET) material, polyamide (PA) material, polyurethan (PU) material, polyvinyl chloride (PVC) material, polyvinyl alcohol (PVOH) material, acrylonitrile butadiene styrene (ABS) material, polycarbonate (PC) material, and polyurethane (PUR) material. Each of the above-described polymer materials comprises at least one component of the respective polymer material. They may comprise two, three or more of the respective polymer components, wherein at least one component, preferably all components may be separated from the polymer-containing waste material by the respective embodiments of the present invention.

[0045] Preferably, the total amount of polymeric non-polyolefin material is less than 13 wt.%, preferably less than 8 wt.%, and most preferably less than 2 wt.%, based on the total weight of the polymer-containing waste material.

[0046] The polymer-containing waste material may further comprise non-polymer material such as impurities, polymer additives, antioxidants, food residues, textiles, residual perfume components, dyes and pigments, wood, paper and ceramics. Preferably, the total amount of non-polymer material is less than 10 wt.%, preferably less than 5 wt.%, and most preferably less than 2 wt.%, based on the total weight of the polymer-containing waste material.

[0047] In one embodiment, the polymer-containing waste material is plastic waste, such as plastic waste obtained from plastic waste management sources as e.g. plastic fractions sorted from municipal solid waste, sorted fractions from produces responsibility organization, industrial waste streams including polymer-rich rejects from waste sorting plants.

[0048] Further examples of polymer-containing waste material include, but are not limited to, low-quality waste streams, e.g. from municipal solid waste, reject streams of sorting or recycling plants, with low polyolefin contents (< 50 wt.%) and a high level of contaminants, such as e.g. biomass, paper, paperboard, cardboard, stones, glass, and other polymers such as PS, ABS, PET, PA and multilayer materials, where their respective polyolefin content is also leveraged. The process preferably allows processing of colored polyolefins, such as black polyolefins, as well as strongly metallized film materials, which both are difficult to sort with NIR sorters. Thus, waste streams comprising high amounts of colored (e.g. black) materials (e.g. plastic waste from automotive, electronics, cable and wiring), which conventionally require sorting with dedicated MIR sorters, may be processed directly.

[0049] Preferably, the polymer-containing waste material is not pre-treated, preferably not chemically pretreated, polymer-containing waste material.

[0050] In step B) of the process, the polymer-containing waste material is contacted with a non-polar solvent comprising, or consisting of, at least one optionally substituted hydrocarbon, such as optionally halogenated hydrocarbon, preferably having from 4 to 10 carbon atoms, to form a composition. Preferably, the optionally substituted hydrocarbon, optionally halogenated hydrocarbon, is selected from the group consisting of linear aliphatic hydrocarbons, such as n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane and n-decane; aromatic hydrocarbons, such as phenol, toluene, xylene, ethylbenzene and tetralin; cyclic hydrocarbons, such as cyclohexane, decalin and tetralin; and chlorinated aromatic hydrocarbons, such as chlorobenzene, dichlorobenzene and trichlorobenzene, and mixtures thereof. The non-polar solvent may comprise further hydrocarbon components, such as other alkanes, alkenes, cycloalkane or aromatic alkanes. Preferably, the non-polar solvent does not comprise any polar components.

[0051] By definition, polar solvents comprise one or more compounds that have a net dipole. Respectively, non-polar solvents do not have a net dipole. Polarity of compounds may be determined empirically. For example, it can be given as Empirical Parameters of Solvent Polarity ET(30) or as the respective normalized values ETN, as e.g. described in Christian Reichardt, “Solvatochromic Dyes as Solvent Polarity Indicators”, Chemical Reviews, 1994, Vol. 94, No.8, page 2319-2358. Preferably, in the meaning of the present invention, non-polar solvents according to the invention have an ETNvalue of up to 0.2, and polar solvents an ETNvalue of above 0.2, respectively. In one embodiment, the non-polar solvent comprises, or consists of, a linear aliphatic hydrocarbon selected from the group consisting of n-butane, n-pentane and n-hexane. These compounds provide satisfying dissolution rates for polyolefin material, however, they do not dissolve polystyrene material. In this embodiment, polystyrene material remains in the undissolved material and may be dissolved by the sequence of process steps comprising the steps B) to E), as described below.

[0052] In another embodiment, the non-polar solvent comprises, or consists of, an aromatic hydrocarbon selected from the group consisting of phenol, toluene and xylene, preferably xylene. These compounds provide even better dissolution rates of polyolefin material, however, they also dissolve polystyrene material. Thus, in this embodiment, polystyrene material may be dissolved together with polyolefin material and may be separated from polyolefin material by the L / L extraction performed in step E1.

[0053] In one particular embodiment, the non-polar solvent is a refinery gasoline fraction comprising hydrocarbons having from 5 to 10 carbon atoms, preferably a refinery light gasoline fraction comprising hydrocarbons having 5 and 6 carbon atoms. The advantage of using refinery gasoline fractions is that they may be withdrawn from the refinery process, used in the present process (in step B and fed back to the refinery process afterwards, i.e. in step E of the process, for further distillation. Such a process may provide economic benefits in particular if the present process is integrated into an oil refinery.

[0054] Preferably, the ratio (wt / wt) of non-polar solvent to the polymer-containing waste material is in the range of 3:1 to 20:1 , more preferably 3:1 to 10:1 and most preferably 3:1 to 5:1 , such as 4:1. For economic reasons, it is preferred that the content of solvent is relatively low. However, lower solvent contents may have negative influence on the dissolution kinetics (e.g. the solution gets highly viscous). Higher pressures may compensate for this drawback. The abovedescribed ratio similarly applies to the dissolution of undissolved material in the process of the present invention. In one embodiment, the contacting step B) is carried out at room temperature (i.e. about 20 °C) and at atmospheric pressure (i.e. about 0.1 MPa).

[0055] In another embodiment, the contacting step B) is carried out at an enhanced temperature, such as at least 50 °C, and preferably at the dissolution temperature (T) and at atmospheric pressure (i.e. about 0.1 MPa).

[0056] In step B) of the process, a composition comprising the polymer-containing waste material and the solvent is formed. Preferably, the composition is a liquid / solid phase system (LS), i.e. comprising the polymer-containing waste material and the liquid solvent.

[0057] In the sequential heating step C), preferably being directly after step B, the composition (C) is heated at a dissolution temperature (T) in the range of 135 to 200 °C and a pressure (P) in the range of 0.1 to 5 MPa for a period of from 5 min to 5 h (M), to obtain a first solution comprising the non-polar solvent and the polyolefin material dissolved in the first solvent and an undissolved material. In the heating step C), polyolefin material is dissolved from the polymer-containing waste material. Preferably, at least 80 wt.%, more preferably at least 90 wt.% most preferably at least 95 wt.% and up to 100 wt.% of polyolefin material, based on the total weight of polyolefin material in the polymer-containing waste material, is dissolved from the polymer-containing waste material. Also, other polymer material may be dissolved from the polymer-containing waste material such as polystyrene material, as well as some of the non-polymer material originally contained in the waste material.

[0058] The undissolved material preferably comprises other polymer components, such as polymeric non-polyolefin material. It may also comprise undissolved polyolefin material, preferably in a low content of up to 10 wt.%, and non-polymer material originally contained in the polymer-containing waste material.

[0059] The dissolution temperature used in step C) generally depends on the content of the polymer-containing waste material, the solvent and the process conditions, such as pressure and dissolution time. Generally, the dissolution temperature (T) is in the range of from 135 to 200 °C, preferably from 135 to 180 °C, more preferably of from 135 to 170 °C and even more preferably of from 135 to 155 °C.

[0060] The invention is based on the knowledge that chemically similar materials can be dissolved in chemically similar solvents (“similia similibus solvuntur”), i.e. nonpolar solvents interact preferably with non-polar materials. Furthermore, it is essential to bring the dissolvable polymer to a thermally higher level (for material softening, swelling and / or solvating the outer surface). Initial experiments indicated that the softening (solvating the outer surface) gets more effective by the application of temperatures nearby the melting temperature of the polyolefin material. Furthermore, low overpressures support the penetration of the solvent into the surface and the outer (accessible) pore structure of the materials. This phenomenon is independent from the way of application the overpressure, i.e. whether it is generated on thermal or hydrodynamic way.

[0061] Generally, the pressure (P) is in the range of 0.1 to 5 MPa, preferably of 0.1 to 4 MPa, more preferably of 0.1 to 3 MPa and most preferably of 0.1 to 2 MPa. Within the meaning of the present invention, all pressures are indicated as absolute pressures, unless otherwise indicated. A pressure above atmospheric pressure may be used, which advantageously increases the dissolution kinetic and thus facilitates dissolution of the solid polymer material mixture. However, dependent on the solvent, atmospheric pressures may be similarly effective. The used pressure is dependent from the vapor pressure of the solvent, being a function of temperature. Usually, the pressure for any dissolution reaction within the present invention is the vapor pressure of the respective solvent at the respective dissolution temperature.

[0062] The dissolution time (M) is generally from 5 min to 5 h, preferably from 10 min to 4 h, more preferably from 20 min to 3 h and most preferably from 30 min to 2 h. In one preferred embodiment, n-hexane is used as the solvent at a dissolution temperature in the range of 135 to 200 °C for a period of 10 min to 3 h, preferably 20 min to 1 h, and preferably at a pressure in the range of 1 to 2.8 MPa.

[0063] In another preferred embodiment, toluene is used as the solvent at a dissolution temperature in the range of 135 to 180 °C for a period of 10 min to 3 h, preferably 20 min to 1 h, and preferably at a pressure in the range of 1 to 2.8 MPa.

[0064] In another preferred embodiment, xylene is used as the solvent at a dissolution temperature in the range of 135 to 137 °C for a period of 30 min to 3 h, preferably 1 to 1.5 h, and preferably at a pressure in the range of 0.1 to 1.5 MPa, more preferably of 0.1 to 1 MPa.

[0065] In a further preferred embodiment, n-decane is used as the solvent at a dissolution temperature in the range of 150 to 170 °C for a period of 1 to 5 h and preferably at pressure in the range of 0.1 to 1 MPa.

[0066] In all embodiments, increasing the dissolution temperatures and / or pressures leads to improved dissolution kinetics, and thus the dissolution period may be shortened.

[0067] Subsequently, and preferably directly after step C), separating step D) is performed, wherein the undissolved material is separated from the first solution. Generally, separation of undissolved material may be carried out by any convention liquid / solid separation technique. Preferably, the liquid / solid separation is performed by gravity settling and / or filtration, preferably hot filtration at a temperature of not less than 30 °C below the dissolution temperature. Preferably, a sieve or a filter, preferably of metal or ceramic material, are used for the (hot) filtration. In a preferred embodiment an adsorption filter (i.e. a filter comprising or consisting of an adsorption material) is used for filtration. In this embodiment, pigments and other coloring agents dissolved in the first solution are also separated from the first solution.

[0068] In one embodiment, preferably of the continuous process, the solvent is removed from a (first) container (such as a first stirred tank) through a sieve, while the undissolved material remains in the sieve. Optionally, the undissolved material is transferred to a second container (such as a second stirred tank), e.g. by means of a screw conveyer / dewatering screw as the transferring aid.

[0069] In further embodiments, the separation of step D) may be carried out as centrifugal or cyclone separation.

[0070] In step E1) of the process, the first solution is contacted with a polar solvent having a Hansen solubility parameter for hydrogen bonds (5h) within the range of 4 to 15 MPa05, preferably a polar aprotic solvent having a Hansen solubility parameter for hydrogen bonds (5h) within the range of 4 to 15 MPa05, the polar solvent being used in an amount within the range of from 1 to 50 vol.-% relative to the volume of the first solution, and extracting polymeric non-polyolefin material into the polar solvent.

[0071] The Hansen solubility parameter 5h is a parameter known in the art which characterizes the solubility of a compound. For a variety of compounds, the value of the Hansen parameter 5h can be looked up in standard chemical books. The Hansen parameters 5h mentioned in this patent application refer to the values tabulated in the following handbook: Hansen, C., Hansen Solubility Parameters - A User's Handbook, 2. Edition, CRC Press, Boca Raton, USA, 2007.

[0072] Ideally, the polar solvent or the polar aprotic solvent is preferably selected such that the solvent does not precipitate the dissolved polyolefin material, but at the same time does extract the polymeric non-polyolefin material. Accordingly, the Hansen solubility parameter for hydrogen bonds (5h) of the polar solvent or the polar aprotic solvent is within the range of 4 to 15 MPa0 5.

[0073] A liquid / liquid phase system (L / L) comprising (i) a second solution comprising the non-polar solvent and polyolefin material dissolved in the non-polar solvent, and (ii) a third solution comprising the polar solvent and polymeric non-polyolefin material dissolved in the polar solvent is obtained. Preferably, in step E1), the first solution and the polar solvent are contacted in counterflow.

[0074] Preferably, the polar solvent is a polar aprotic solvent, preferably comprising at least one compound selected from the group consisting of ketones, such as acetone, methyl ethyl ketone, methyl butyl ketone or methyl iso-butyl ketone; cyclic ethers, such as tetrahydrofuran; sulfoxides, such as di-methyl sulfoxide; amides, such as dimethylformamide or dimethylacetamide; lactams, such as N-methyl-2-pyrollidone; any of these com-pounds in combination with a soluble metal chloride, such as LiCI or CaCl2; and any combination thereof.

[0075] Preferably, the polar solvent is a polar protic solvent, preferably comprising at least one compound selected from the group consisting of alcohols, such as methanol, ethanol, n-propanol, iso-propanol, n-butanol or iso-butanol, optionally in combination with a soluble metal chloride, such as LiCI or CaCI2; fluorinated alcohols, such as hexafluoro isopropanol; and halogenated carbonic acids, such as trichloroacetic acid; and any combination thereof.

[0076] Preferably, the extraction of step E1) has a separation factor a of more than 2 more preferably more than 5, and most preferably more than 10 and the nonpolar solvent and the polar solvent are essentially immiscible.

[0077] The separation factor a is a dimensionless quantity that measures the ability of a separation process to distinguish between two components in a mixture. It is defined as the ratio of the concentrations of two components in one phase to the ratio of their concentrations in the other phase. A value of a=1 means no separation occurs, while a higher value indicates a better separation performance.

[0078] Preferably, the ratio (wt / wt) of polar solvent to the first solution in step E1) is in the range of 1:1 to 1 :20, more preferably 1 :1 to 1 :10 and most preferably 1 :1 to 1:5.

[0079] In one embodiment, the contacting step E1) is carried out at room temperature (i.e. about 20 °C) and at atmospheric pressure (i.e. about 0.1 MPa).

[0080] In another embodiment, the contacting step E1) is carried out at an enhanced temperature, such as at least 50 °C, and preferably at the dissolution temperature (T) and at atmospheric pressure (i.e. about 0.1 MPa).

[0081] In step E2) of the process, the third solution is separated from the second solution. Generally, the separation may be carried out by any convention liquid / liquid separation technique. Preferably, the liquid / liquid separation is performed by e.g. decanter, decanter centrifuge, disc stack separator or combinations of them

[0082] Preferably, the polymeric non-polyolefin material in the third solution separated in step E2) is recovered. Recovering is done by a vapor-liquid separation step, preferably a flash separation step or a devolatilization or a combination of the mentioned techniques.

[0083] In step F) of the process, the non-polar solvent is removed from the second solution.

[0084] Preferably, removing the non-polar solvent from the second solution of step F) is performed by evaporating the non-polar solvent or by precipitating the polyolefin material, preferably by cooling the second solution or by adding a sufficient amount of a second polar solvent, followed by filtration.

[0085] Preferably, the non-polar solvent removed in step F) is recovered and optionally reused in step B).

[0086] In step G) of the process, the polyolefin material obtained in step F) is further treated in a chemical recycling process. The chemical recycling process is preferably a thermochemical recycling process, such as a pyrolysis process, a gasification process or a waste steam cracking process. Most preferably, the chemical recycling process is a pyrolysis process. One advantage of the invention is that this subsequent chemical recycling process of step G), such as a pyrolysis process, can be run with a higher purity stream, i.e. a higher PO content, and thus improves the overall yield of the plastic waste recycling process. It is understood that running with a higher purity input stream is beneficial for any type of chemical recycling process so the present invention is not limited to the use of a pyrolysis process in step G). Gasification processes or waste steam cracking processes can also be considered to be used in step G) of the process. A higher purity input stream to step G), as obtained after steps A) to F) in the process, will result in a higher purity outlet stream after step G) which reduces or completely removes the requirements for often costly further post-treatment. However, the achieved advantage is the greatest when the chemical recycling process is a pyrolysis process since this type of chemical recycling is in general much more sensitive to the purity of the input stream and would not be able to handle low quality mixed plastic waste as such.

[0087] The obtained outlet stream from the chemical recycling step G) constitutes liquefied and / or gasified plastic waste, e.g. when a pyrolysis step is used this may be the obtained pyrolysis oil and / or pyrolysis gas, which may then be further treated in for example cracker, refinery and / or fractionation steps which are all well known in the art.

[0088] Preferably, the process further comprises a sub-process of reducing the size, preferably by grinding and optionally size-separating, of the polymer-containing waste material before step A), to provide polymer-containing waste material particles, preferably having a particle size of from 10 pm to 20 mm, as determined by the sieve analysis described herein below. This improves processability of the polymer containing waste material and maximizes its surface area for the following dissolution step. All these sub-processes reducing the size of the polymer-containing waste material are common processes well-known in the art. The plastic waste recycling process according to the invention comprises extracting polyolefins from polymer-containing waste material according to any one of the above-described embodiments, and further comprises step G) of treating the polyolefin material obtained in step F) in a chemical recycling process, preferably pyrolysis.

[0089] The present invention also relates to liquefied plastic waste obtainable or obtained by a process according to any one of the above-described embodiments.

[0090] In particular, the liquefied plastic waste is the liquefied hydrocarbon stream obtained after step G) of the process according to the present invention, the chemical recycling step. Preferably, the liquefied plastic waste is the liquefied hydrocarbon stream obtained after step G) of the process wherein step G) is a pyrolysis process.

[0091] The present invention also relates to gasified plastic waste obtainable or obtained by a process according to any one of the above-described embodiments. In particular, the gasified plastic waste is the gasified hydrocarbon stream obtained after step G) of the process according to the present invention, the chemical recycling step. Preferably, the gasified plastic waste is the gasified hydrocarbon stream obtained after step G) of the process wherein step G) is a pyrolysis process.

[0092] Methods

[0093] The following definitions of terms and measurement and determination methods apply to the above general description of the invention as well as to the below examples.

[0094] a) FTIR

[0095] The amount of “iPP”, “PVC”, “PA”, “PET”, “PS” and “PE” was determined by Transmission InfraRed spectroscopy.

[0096]

[0097] All calibration samples and samples to be analyzed are prepared in similar way, on molten pressed plates. 2 to 3 g of compounds to be analyzed are molten at 190°C curve, 20 seconds under 60 to 80 bar pressure, in an hydraulic heating press and cooled down to room temperature during 40 second in a cold press under the same pressure, in order to control the morphology of the compound. The thickness of the plates are controlled by metallic calibrated frame plates 2.5 cm by 2.5 cm, 100 to 200 pm thick (depending MFR from the sample); two plates are produced in parallel at the same moment and in the same conditions. The thickness of each plate is measured before any FTIR measurements; all plates are between 100 to 200 pm thick.

[0098] To control the plate surface and to avoid any interference during the measurement, all plates are pressed between two double-sided silicone release papers. In case of powder samples or heterogeneous compounds, the pressing process would be repeated three times to increase homogeneity by pressed and cutting the sample in the same conditions as described before.

[0099]

[0100] Standard transmission FTIR spectroscope such as Bruker Vertex 70 FTIR spectrometer is used with the following set-up:

[0101] • a spectral range of 4000-400 cm-1,

[0102] • an aperture of 6 mm,

[0103] • a spectral resolution of 2 cm-1,

[0104] • with 16 background scans, 16 spectrum scans,

[0105] • an interferogram zero filling factor of 32

[0106] • Norton Beer strong apodisation.

[0107] Spectrum are recorded and analysed in Bruker Opus software.

[0108] Calibration samples:

[0109] As FTIR is a secondary method, several calibration standards were compounded to cover the targeted analysis range, typically from:

[0110] • 0.2 wt% to 2.5 wt.% for PA

[0111] • 0.1 wt% to 5 wt.% for PS • 0.1 wt.% to 5 wt.% for PET

[0112] • 0.1 wt.% to 4 wt.% for PVC

[0113] The following commercial materials were used for the compounds: Borealis HC600TF as iPP, Borealis FB3450 as HDPE and for the targeted polymers such RAMAPET N1S (Indorama Polymer) for PET, Ultramid® B36LN (BASF) for Polyamide 6, Styrolution PS 486N (Ineos) for High Impact Polystyrene (HIPS), and any commercial PVC.

[0114] All compounds are made at small scale in a Haake kneader at a temperature below 265°C and less than 10 minutes to avoid degradation.

[0115] Additional antioxidant such as Irgafos 168 (3000 ppm) is added to minimize the degradation.

[0116] Calibration:

[0117] The FTIR calibration principal is the same for all the components: the intensity of a specific FTIR band divided by the plate thickness is correlated to the amount of component determined by 1 H or 13C solution state NMR on the same plate. Each specific FTIR absorption band is chosen due to its intensity increase with the amount of the component concentration and due to its isolation from the rest of the peaks, whatever the composition of the calibration standard and real samples.

[0118] This methodology is described in the publication from Signoret and al. “Alterations of plastic spectra in MIR and the potential impacts on identification towards recycling", Resources, conservation and Recycling journal, 2020, volume 161, article 104980.

[0119] The wavelength for each calibration band is:

[0120] • 3300 cm-1for PA,

[0121] • 1601 cm-1for PS,

[0122] • 1409 cm’1for PET, 615 cm’1for PVC,

[0123] 1167 cm’1for iPP.

[0124] For each polymer component i, each calibration correlation is the following:

[0125] Fi

[0126] xi = Ai. — d I- Bi

[0127] where Xi is the fraction amount of the polymer component i (in wt%);

[0128] Ei is the absorbance intensity at the polymer component i specific band (in a.u. absorbance unit), respectively at 3300 cm’1for PA, 1601 cm’1for PS, 1409 cm’1for PET, 615 cm’1for PVC, 1167 cm’1for iPP;

[0129] d is the thickness of the sample plate;

[0130] Ai and Bi are two coefficients of correlation determined for each calibration curve.

[0131] No specific isolated band can be found for PE and as consequence,

[0132] XPE = 100 — (XiPP + XPA + XPS + XPET + XPVc)

[0133] where 100 stands for the amount of polymer in the sample, and the amount of polymer is generally determined by the ash content.

[0134] For each calibration standard, the amount of each component is determined by the initial sample amount added into the compound.

[0135] b) Ash content (amount of inorganic fillers)

[0136] Thermogravimetric Analysis (TGA) experiments were performed with a Perkin Elmer TGA 8000. Approximately 10-20 mg of materials were placed in a platinum pan. The temperature was equilibrated at 50°C for 10 minutes, and afterwards raised to 950°C under nitrogen at 20°C / min. The ash content was evaluated as the wt% at 850 °C, based on the total weight of the used starting material.

[0137] c) Particle size determination Particle sizes, in particular particle sizes of waste material, are determined by classifying (dry) sieve analysis, sieving performed as described in DIN 66165 (in particular, DIN 66165-2 describing the analysis method), e.g. using sieves according to ISO 565 with nominal aperture size of 22.4 mm etc. The particle sizes are preferably D90 particle sizes.

[0138] d) Determination of the Xylene hot insoluble (XHI) and xylene hot soluble (XHS) fraction

[0139] Approximately 3 g of the waste samples 1 and 2 was weighed out exactly. Each of the samples was placed in a pouch made of stainless steel mesh of the following material (“DRAHTGEWEBE Materialqualitat: Edelstahl 1.4401”), which was placed in a round flask filled with 700 mL of xylene (ortho- or para-xylene, with a purity chromatography >98%). Xylene was kept under reflux conditions for 5h. The pouch containing the insoluble matter was taken out of the flask, washed from the polymer solution residues with a fresh portion of xylene for another 30 minutes. Afterwards the pouch was dried under vacuum at 90°C.

[0140] After cooled to room temperature in a desiccator, the pouch is weighed out exactly to the nearest 0.1 mg (m3).

[0141] m3— (m2— m-J

[0142] %XHI = * 100

[0143]

[0144] m1

[0145] XHI = Xylene hot insoluble amount

[0146] mi = sample weight in g

[0147] m2 = weight of pouch with the sample in g

[0148] m3 = weight of pouch with the insoluble residue in g The amount of the fraction which is soluble in xylene at 135°C (XHS) is than calculated - by subtracting %XHI:

[0149] %XHS = 100 - %XHI

[0150] The composition of the XHS and XHI was then done by FTIR analysis.

[0151] Examples

[0152] Polyolefin extraction process

[0153] The investigated plastic waste feedstock sample compositions are summarized in the following table.

[0154] Material Composition

[0155] M1 Multilayer material as typically 84 wt.% PE, 5.8 wt.% PP, 8.8 wt.% used for medical applications PA, 0.25 wt.% PET, < 0.05 wt.% PUR (composition provided by supplier)

[0156] M2 Mixed-plastic material produced Produced from residue of lightweight from DSD 350 / 352 post-consumer packaging (LWP) sorting, comprising waste fractions (commercially availaPP, PE, PET, PS articles (including ble as reduction agent for steel mills) multilayer packaging).

[0157] Typical composition of ca. 50-55 wt.% PO, and the rest comprising cellulose (paper), PET, PA and other polymeric non-polyolefin material, e.g. nitrile rubber.

[0158]

[0159] Determination of the PO content was done by dissolving the polyolefin fraction in xylene at 135°C under reflux and analyzing the dissolved fraction by FTIR analysis as described above in the methods section.

[0160] Material Xylene soluComposition XHI Composition ble fraction of XHS- of XHI at 135 °C 135°C

[0161] (XHS-135°C)

[0162] M1 83.6 wt.% 99 wt.% 16.4 wt.% PA

[0163] LDPE

[0164] 1 wt.% PP

[0165] M2 60.8 wt.% PP: 47 wt.% 39.2 wt.% Cellulose,

[0166] PET, PA PE: 51 wt.%

[0167] PS: ca. 0.5

[0168] wt.%

[0169] EVA: ca. 0.5

[0170] wt.%

[0171] Filler: ca. 1

[0172] wt.%

[0173]

[0174] Extraction process with aprotic solvent (NMP, DMF + LiCI)

[0175] Approximately 2 g of each of the samples was weighed out. Each sample was placed in a pouch made of stainless steel mesh of the following material (“DRAHTGEWEBE Materialqualitat: Edelstahl 1.4401”), which was placed in a round flask filled with 150 mL of an aprotic solvent. The aprotic solvent was prepared by dissolving between 0.1 and 2.0 wt.% of LiCI in N-Methyl-2-pyrrolidone (NMP) (with a purity chromatography >98 %) or alternatively in Dimethylformamide (DMF).

[0176] The aprotic solvent was kept at 85°C for 2 h to extract polar polymers like PA, PET, PVC.

[0177] In another example the aprotic solvent was kept at 60°C for 2h to extract the polar polymers like PA, PET, PVC.

[0178] In another example the aprotic solvent was kept at 110°C for 2h to extract the polar polymers like PA, PET, PVC.

[0179] By evaporating the aprotic solvent from the aprotic solvent filtrate or alternatively a polyamide and / or polyethylene terephthalate fraction was obtained as residue. The PA / PET residue was dried at 90 °C under vacuum. This polymer fraction containing polyamide and / or polyethylene terephthalate is called PA / PET fraction.

[0180] The pouch containing the remaining non-dissolved PO fraction was taken out of the flask and washed with 200 ml distillated water for 30 minutes at 60°C to remove any potential LiCI. The metal pouch was dried overnight at 60 °C in a vacuum oven and weighted out before further testing.

[0181] Results

[0182] The percentage of the different polymer fractions (fraction insoluble in aprotic solvent and extracted fraction using aprotic solvent) in the polymeric material used was obtained gravimetrically:

[0183] wt. % polymer fraction = —

[0184]

[0185] mo

[0186] where: mo is the mass of the sample test portion weighed, in grams;

[0187] rm is the mass of the separated solid after drying, in grams;

[0188] (for the insoluble fraction, ml is the mass of the residue - the mass of the metal pouch)

[0189] The polymer fractions were further analyzed for their content by the FTIR spectroscopy, as described in the method section.

[0190] The composition of the samples (potential feedstock) was determined as in soluble fraction in the aprotic solvent (PO + inorganics & cellulose), aprotic fraction (PS, Nitril, PA and PET) and are summarized in table 1 (M1) and table 2 (M2).

[0191] Table 1 Extraction with aprotic solvent for Material M1

[0192] Experiment M1-1 M1-2 M1-3 M1-4 M1-5 M1-6 Temperature °C 60 85 110 60 85 110 Solvent NMP NMP NMP DMF DMF DMF LiCI wt.% 0.1 1.05 2.00 2 1.05 0.1 Aprotic fracwt.% 1.3 14.8 16.6 1.9 1.7 1.4 tion

[0193] Insoluble wt.% 98.7 85.2 84.4 98.1 98.3 98.7 fraction

[0194] Extraction % 8 90 100 11 10 8 rate

[0195]

[0196] Table 2 Extraction with aprotic solvent for Material M2

[0197] Experiment M2-1 M2-2 M2-3 M2-4 M2-5 M2-6

[0198]

[0199] Temperature °C 60 85 110 60 85 110 Solvent NMP NMP NMP DMF DMF DMF LiCI wt.% 0.1 1.05 2.00 2 1.05 0.1 Aprotic fracwt.% 15.2 15.6 18.7 16.1 14.2 15.9 tion

[0200] Insoluble wt.% 98.7 85.2 84.4 98.1 98.3 98.7 fraction

[0201] Extraction % 39 40 48 41 36 40.5 rate

[0202]

[0203] The composition of the extracted fraction as well as of the remaining PO fraction is summarized below in table 3 (M1) and table 4 (M2).

[0204] Table 3 Composition of extracts and residues of M1

[0205] Experiment M1-1 M1-2 M1-3 M1-4 M1-5 M1-6 Aprotic fracMainly Mainly Mainly Mainly Mainly Mainly tion PS PS PS, PS, PS, PS, PA, PET, PET, PET, PET

[0206] Nitril Nitril Nitril Insoluble Mainly Mainly PP, PE + Mainly Mainly Mainly fraction PP, PE PP, PE + PP, PE + PP, PE +

[0207] + PS, cellulose

[0208] cellulose cellulose cellulose cellulose

[0209]

[0210] Table 4 Composition of extracts and residues of M2

[0211] Experiment M2-1 M2-2 M2-3 M2-4 M2-5 M2-6 Aprotic fracPE, PA PA PA LDPE, LDPE, LDPE, PS, tion PS, EVA PS, EVA EVA Insoluble PE, PA PE + PE + PA PE + PA PE + PA fraction

[0212] cellucellulose

[0213] lose

[0214]

[0215] L / L polyolefin extraction process

[0216] Approximately 80 mg of each of the samples is weighed out. The sample is placed in a pouch made of stainless steel mesh of the following material (“DRAHTGEWEBE Materialqualitat: Edelstahl 1.4401”), which is placed in a 16 mL GC Headspace vial. 5 ml of n-decane (with a purity chromatography >98 %). N-decane is added and the solution is kept for dissolution at 160°C for 3 h. The experiments were performed at ambient pressure, i.e. about 0.1 MPa.

[0217] For further cleaning 5 mL of a solution of 1.05 wt.% LiCI in N-Methy-2-pyrrolidone (NMP) is added at 130°C to the n-decane solution. Under high steering an emulsion is formed (magnetic stirrer using more than 700 rpm), which is kept for 1 hour at 130°C.

[0218] The N-Methyl-2-pyrrolidone phase is separated from the n-decane phase by stopping the stirring. The NMP solution having a higher density than n-decane is separated by density separation. By evaporating the N-Methyl-2-pyrrolidone from the N-Methyl-2-pyrrolidone phase polar impurities as well as PA, PET are obtained as residue. The residue is dried at 90 °C under vacuum overnight. This polymer fraction containing polyamide and / or polyethylene terephthalate obtained by L / L extraction is called L / L fraction. The pouch containing the insoluble matter is taken out of the flask, washed from the polymer solution residues with a fresh portion of n-decane for another 30 minutes. Afterwards the pouch is dried under vacuum at 90 °C.

[0219] The PO fraction is obtained by evaporating the combined n-decane solutions under vacuum (~100 mbar) at a temperature of 100°C. Afterwards the polymer solution residues are dried under vacuum at 90°C.

[0220] Comparative Example (process without L / L separation)

[0221] Approximately 80 mg of each of the samples is weighed out. The sample is placed in a pouch made of stainless steel mesh of the following material (“DRAHTGEWEBE Materialqualitat: Edelstahl 1.4401”), which is placed in a 16 mL GC Headspace vial. 5 ml of n-decane (with a purity chromatography >98 %). N-decane is added and the solution is kept for dissolution at 160°C for 3 h. The experiments were performed at ambient pressure, i.e. about 0.1 MPa.

[0222] The polymer dissolved in the aliquot of 5 ml n-decane is precipitated with 10 mL of cold acetone (< 8 °C). For economic reasons, it is preferred that the content of solvent is relatively low. However, lower solvent contents may have negative influence on the dissolution kinetics (e.g. the solution gets highly viscous). Higher pressures may compensate for this drawback. The filtration step is performed using filter paper e.g. Whatman No. 4, No 541 or corresponding, with diameter of at least 125 mm. The filtered solid fraction is dried overnight at 60 °C in a vacuum oven and weighted out before further testing.

Claims

Claims1. A plastic waste recycling process comprising the steps of:A) providing polymer-containing waste material comprising polyolefin material,B) contacting the polymer-containing waste material with a non-polar solvent, preferably comprising at least one optionally substituted hydrocarbon, such as optionally halogenated hydrocarbon, to form a composition,C) heating the composition at a dissolution temperature (T) in the range of from 135 to 200 °C and a pressure (P) in the range of from 0.1 to 5 MPa abs. for a period of from 5 min to 5 h (M), to obtain a first solution comprising the non-polar solvent and polyolefin material dissolved in the non-polar solvent, and an undissolved solid material,D) separating the undissolved solid material from the first solution, E1) contacting the first solution with a polar solvent having a Hansen solubility parameter for hydrogen bonds (5h) within the range of 4 to 15 MPa05, preferably a polar aprotic solvent having a Hansen solubility parameter for hydrogen bonds (5h) within the range of 4 to 15 MPa05, the polar solvent being used in an amount within the range of from 1 to 50 vol.-% relative to the volume of the first solution, and extracting polymeric non-polyolefin material into the polar solvent, thereby obtaining a liquid / liquid phase system comprising(i) a second solution comprising the non-polar solvent and polyolefin material dissolved in the non-polar solvent, and (ii) a third solution comprising the polar solvent and optionally present polymeric non-polyolefin material dissolved in the polar solvent,E2) separating the third solution from the second solution,wherein the sequences of steps E1) and E2) can be performed before or after step D),F) removing the non-polar solvent from the second solution to obtain polyolefin material in solid form; andG) further treating the polyolefin material obtained in step F) in a chemical recycling process.

2. The process according to claim 1, wherein the polymer-containing waste material comprises from 35 to 90 wt.% of polyolefin material, based on the total weight of the polymer-containing waste material, and / or wherein the total amount of the non-polymer material is less than 10 wt.% based on the total weight of the polymer-containing waste material.

3. The process according to any one of the preceding claims, wherein the polymer material of the polymer-containing waste material further comprises at least one polymer material, preferably a polymeric nonpolyolefin material, selected from the group consisting of polystyrene (PS) material, polyethylene terephthalate (PET) material, polyamide (PA) material, polyurethan (Pll) material, polyvinyl chloride (PVC) material, polyvinyl alcohol (PVOH) material, acrylonitrile butadiene styrene (ABS) material, polycarbonate (PC) material, and polyurethane (PUR) material.

4. The process according to any one of the preceding claims, wherein in step E1), the first solution and the polar solvent are contacted in counterflow.

5. The process according to any one of the preceding claims, wherein the at least one optionally substituted hydrocarbon of the non-polar solvent has 4 to 10 carbon atoms and is preferably selected from the group consisting of linear aliphatic hydrocarbons, such as n-butane, n-pentane, n-hexane, n- heptane, n-octane, n-nonane or n-decane; aromatic hydrocarbons, such asbenzene, toluene, xylene, ethylbenzene or tetralin; cyclic hydrocarbons, such as cyclohexane, decalin or tetralin; chlorinated alkanes, such as tetrachlorethane, tetrachlorethene, and chlorinated aromatic hydrocarbons, such as chlorobenzene, dichlorobenzene or trichlorobenzene; and any combination thereof.

6. The process according to any one of the preceding claims, wherein the polar solvent is a polar aprotic solvent, preferably comprising at least one compound selected from the group consisting of ketones, such as acetone, methyl ethyl ketone, methyl butyl ketone or methyl iso-butyl ketone; cyclic ethers, such as tetrahydrofuran; sulfoxides, such as dimethyl sulfoxide; amides, such as dimethylformamide or dimethylacetamide; lactams, such as N-methyl-2-pyrollidone; any of these compounds in combination with a soluble metal chloride, such as LiCI or CaCl2; and any combination thereof, orwherein the polar solvent is a polar protic solvent, preferably comprising at least one compound selected from the group consisting of alcohols, such as methanol, ethanol, n-propanol, iso-propanol, n-butanol or iso-butanol, optionally in combination with a soluble metal chloride, such as LiCI or CaCl2; fluorinated alcohols, such as hexafluoro isopropanol; and halogenated carbonic acids, such as trichloroacetic acid; and any combination thereof.

7. The process according to any one of the preceding claims, wherein the extraction of step E1) has a separation factor a of more than 2, preferably more than 5 and most preferably more than 10 and the non-polar solvent and the polar solvent are essentially immiscible.

8. The process according to any one of the preceding claims, wherein the process comprises a sub-process of reducing the size, preferably by grinding and optionally size-separating, of the polymer-containing waste material before step A), to provide polymer-containing waste material particles, preferably having a particle size of from 10 pm to 20 mm.

9. The process according to any one of the preceding claims, wherein removing the non-polar solvent from the second solution of step F) is performed by evaporating the non-polar solvent; or by precipitating the polyolefin material, preferably by cooling the second solution or by adding a sufficient amount of a second polar solvent, followed by filtration.

10. The process according to any one of the preceding claims, wherein the nonpolar solvent removed in step F) is recovered and optionally reused in step B).

11. The process according to any one of the preceding claims, wherein the polymeric non-polyolefin material in the third solution separated in step E2) is recovered.

12. The process according to any one of the preceding claims, wherein the chemical recycling process is a pyrolysis process.

13. Liquefied plastic waste obtainable by the process according to any one of claims 1 to 12, wherein the liquefied plastic waste is obtained after conducting step G).

14. Gasified plastic waste obtainable by the process according to any one of claims 1 to 12, wherein the gasified plastic waste is obtained after conducting step G).

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