Method and apparatus for removing impurities from impure extrudable material

Abstract

A method of extruding a recycled polymer from an impure extrudable material includes injecting a liquid non-solvent into a device and mixing the non-solvent with the impure extrudable material substantially homogeneously, thereby forming a dispersion of the non-solvent and the impure extrudable material. Gaseous impurities are output from the device.

Description

Technical Field

[0001] The present invention comprises a method, apparatus and recycled polymer for extruding a recycled polymer from an impure extrudable material. Background Art

[0002] It is known that there are many patent applications that teach methods for recycling polymers and include decontamination or cleaning of recycled polymers. For example, International Patent Application No. WO2021 / 123475 teaches a method for decontaminating recycled plastics such as polyethylene (PE), polypropylene (PP) or polyester (PET) from plastic waste. The disclosed method includes a step of mixing recycled plastic polymers containing organic pollutants with a water-soluble solvent in an extractor. Then, a centrifugation step is applied to the mixture of the recycled plastic polymer and the water-soluble solvent so that the organic pollutants contained in the recycled plastic polymer can be transferred to the water-soluble solvent in the liquid phase.

[0003] International patent application number WO2020 / 0245476A1 teaches a method for removing volatile organic compounds that cause odor in recycled plastics. The method includes the step of injecting water (steam) in a gas phase into a distillation column containing recycled plastics. Volatile organic compounds are removed from the recycled plastics by distillation, and then the volatile organic compounds are output together with water / steam through the upper part of the distillation column.

[0004] European patent application number EP0377115A2 describes a method for extruding a low-odor polyphenylene ether / polystyrene resin from a solution containing a polyphenylene ether resin and a polystyrene resin. The method for extruding a polyphenylene ether / polystyrene resin includes a first step of mixing a solution containing a polyphenylene ether resin and a liquid aromatic hydrocarbon solvent in a first device. A second step includes heating the liquid polymer solution and outputting a first portion of volatiles in gaseous form. The second step produces a partially devolatilized polymer solution. The partially devolatilized polymer solution is then transferred to a second device. Steam or water is injected into the partially devolatilized polymer solution, and a second portion of impurities is output from the partially devolatilized polymer solution.

[0005] International Patent Application No. WO2006 / 097470 has taught the method for removing residual styrene monomer from the blend comprising polystyrene and polyvinyl pyrrolidone.The method is included in the blend comprising polystyrene and polyvinyl pyrrolidone and mixed with water in a container.Steam is injected into the container comprising polystyrene, polyvinyl pyrrolidone and water, and dehydrated by condensation simultaneously.In one aspect of the method, an inert gas such as a stream of nitrogen or argon is injected into the container comprising polystyrene, polyvinyl pyrrolidone and water, rather than injecting water.

[0006] Japanese patent application number JP2002 / 097362 describes a method for producing a molding resin with improved odor properties. The resin is a virgin polymer used in electronic components. The method includes the steps of introducing a polyphenylene ether-based resin and a polystyrene-based resin into an extruder and melt-kneading the polyphenylene ether-based resin and the polystyrene-based resin. Liquid water is injected into the extruder. The polyphenylene ether-based resin and the polystyrene-based resin are subjected to a step of degassing by reduced pressure. Degassing enables the removal of odor from the polyphenylene ether-based resin and the polystyrene-based resin. The odor is residual monomers contained in the polyphenylene ether-based resin, oligomers contained in the polystyrene-based resin, and volatile components. Volatile components are, for example, volatile components or other by-products produced by decomposing the polystyrene-based resin during reduced pressure. In other examples, the volatile components are styrene monomers, 2,4,6-trimethylanisole, 7-methyldihydrobenzofuran, 2,3-dihydrobenzofuran, toluene or ethylbenzene.

[0007] German patent application number DE808788 relates to a method for improving the properties of polystyrene or styrene copolymers containing volatile organic compounds. The method comprises the steps of suspending polystyrene or styrene copolymers in water in a closed container in the form of beads or particles. Water vapor is injected into the container. The water vapor in the container is then discharged from the container so that the volatile organic compounds in the water vapor can be transported.

[0008] German patent application DE3840293A1 discloses a method for removing monomeric and / or oligomeric impurities from components produced by polymerization. The components are virgin polymers, and the method includes the use of an extractant, namely supercritical carbon dioxide. However, the method disclosed in the patent application is uneconomical because it is expensive and difficult to keep the supercritical carbon dioxide in a supercritical state.

[0009] Japanese patent JP4790517B2 discloses a method and apparatus for producing a thermoplastic resin composition. The thermoplastic resin composition is any one of a mixture of a polymer alloy, a polymer blend, a thermoplastic resin and a filler. The method includes supplying the thermoplastic resin composition to a plasticizing portion by a supply port of the device, and melting the thermoplastic resin composition in the plasticizing portion. Liquid carbon dioxide is injected into the kneading portion of the device, and the thermoplastic resin composition is kneaded under a high pressure of 10 MPa or higher and lower than 20 MPa. The method also includes vacuum suction via an exhaust port in the vacuum exhaust portion of the device to depressurize. Depressurization is performed with a pressure gradient of 3 MPa / sec or higher and lower than 10 GPa / sec to remove carbon dioxide from the mouth die of the device.

[0010] U.S. Patent Application US5204410A discloses a method for removing volatile substances from polypropylene ether or polypropylene ether / styrene resin composition. The resin composition taught in this patent application is a primary polymer and is used for food contact. The volatile substances are typically typical styrene, catalyst fragments, such as trimethylanisole, trialkylamines, toluene, methyldihydrobenzofuran, dihydrobenzofuran, dimethylcyclohexanone, ethylhexenal, various amines. The method used in this patent application is not used for the recycling of plastics. Carbon dioxide rather than water is proposed as an extractant. However, the combination of carbon dioxide and water is not taught in this document.

[0011] U.S. patent application US5851065A discloses a method and apparatus for recycling resin waste. The resin waste includes a thermosetting resin paint film and a thermoplastic resin matrix, and is supplied to the passage of the barrel. The resin waste is then melted to form a melt, and the melt is delivered from the upstream side of the barrel passage to the downstream side by a screw array. The thermosetting resin in the melt is hydrolyzed by a hydrolyzing agent (such as water). The melt forms a highly filled area, and a resistor is used to limit the flow of the melt and thereby enhance the contact efficiency with the resin waste and water. Hydrolysis causes the three-dimensional cross-linked structure of the resin waste to be broken into decomposed components. The water produced by the hydrolysis of the resin waste is degassed by vaporizing the water, and the decomposed components are partially discharged together with the water by the vaporization of water. The method described in the document is not as effective as using water to remove impurities from the melt of the virgin polymer, because the decomposed components are not fully diffused through the melt of the recycled plastic.

[0012] European patent application EP0375937A2 discloses a method for reducing impurities in a composition. The composition is a substantially odorless and tasteless virgin polymer for food contact applications. The composition comprises a single polyphenylene ether resin or a polyphenylene ether resin in combination with a styrene resin, and also has impurities selected from the following: styrene monomer, toluene, volatile odorous oxygen-containing species, volatile odorous amine sources, mixtures of any of them, and the like. The method comprises extruding the composition at a temperature above the melting point of the composition. Extrusion is performed once in at least two stages. The two stages include water injection, followed by vacuum exhaust.

[0013] International patent application WO2012 / 108245A1 discloses a method for making a virgin polymer in the form of a polycarbonate resin. The polycarbonate resin pellets have a reduced methylene chloride content. The method includes starting from a polycarbonate resin in the form of a specific powder or granules and moving the polycarbonate resin in an inert gas atmosphere having an oxygen concentration of 3% by volume or less. The polycarbonate resin falls 50 cm or longer in the inert gas atmosphere. A specified amount of water having a conductivity of 30 μS / cm or less is injected into the kneading zone of the extruder. The other steps of the method are to remove methylene chloride from the polycarbonate resin together with water and to adjust the moisture concentration in the polycarbonate resin to 10-200 ppm by draining through a vent disposed downstream of the kneading zone. The strand-shaped molten resin is extruded into a water bath through a die. The introduction of the strand-shaped molten resin enables the strand-shaped molten resin to be cooled. The strand-shaped molten resin is cut at 70-130°C to produce pellets. The method further includes allowing the pellets having a moisture content of 10-200 ppm to further absorb water in a humid atmosphere, thereby adjusting the moisture content of the pellets to a value higher than the initial moisture content of the pellets and equal to or lower than 1300 ppm.

[0014] Korean patent application KR20120029407A discloses an apparatus and method for devolatilizing a solvent-containing polycarbonate solution to produce a virgin polymer of polycarbonate. The apparatus includes a devolatilizer and an extruder. The method includes injecting an inert component such as nitrogen, argon, carbon dioxide, water, methane or helium into a polymer melt stream upstream of a downflow devolatilizer and mixing. The inert component is injected into the extruder as an azeotropic additive.

[0015] These prior art methods describe the production of virgin polymers, i.e. newly manufactured polymers, wherein the residual concentration of impurities in the virgin polymer is a maximum of 250 ppm. Impurities are introduced into the virgin polymer intentionally during the production process of the virgin polymer. Impurities are, for example, used solvents and used monomers introduced during production. These intentionally introduced solvents and monomers must subsequently be removed from the polymer melt of the virgin polymer.

[0016] The recycled polymers described in the prior art contain short chain segments. One challenge with melts composed of recycled polymers is the formation of "gels" within the melt. Any water placed in the melt will not disperse in the polymer gel, and therefore the water cannot remove impurities incorporated into the polymer gel. Therefore, these impurities will remain when the melt is re-extruded.

[0017] International patent application WO2021 / 048756Al discloses a method for recovering vulcanized rubber and desulfurizing it. Water is used to cut the sulfur bonds in the rubber. The document does not teach the use of carbon dioxide and water together. Summary of the invention

[0018] In the present invention a method for extruding a recycled polymer from an impure extrudable material is taught. The method comprises injecting a non-solvent in a liquid state into a device and mixing the non-solvent with the impure extrudable material substantially uniformly, thereby forming a dispersion of the non-solvent and the impure extrudable material. The non-solvent in a liquid state is injected into an extruder, which obtains a uniform dispersion of the non-solvent in a liquid state with the impure extrudable material. Forming a dispersion of the non-solvent and the impure extrudable material simultaneously enables the removal of impurities from the impure extrudable material and the obtaining of a gas phase comprising the impurities and the non-solvent. Thus, in the method there is no need to apply two separate steps to firstly separate the impurities from the impure extrudable material and secondly to evaporate the impurities and the non-solvent.

[0019] Recycled polymers are polymers made from post-consumer waste or industrial waste and in one aspect of the invention have an impurity concentration of less than 10 ppm.

[0020] The method described in the present invention is capable of purifying impure extrudable materials by removing a majority of impurities from the impure extrudable materials. The method produces a recycled polymer having a residual concentration of impurities in the recycled polymer of less than 100 ppm, and in another aspect less than 10 ppm.

[0021] Impurities in recycled polymers are substances such as food that are unintentionally introduced into polymer waste. More than 30 different types of impurities have been found to be present in recycled polymers, such as polar and non-polar, protic and non-protic impurities. Due to the effects of residual impurities on the odor, taste, feel and strength of recycled polymers, these impurities must be removed from recycled polymers.

[0022] The method described in the present invention complies with Regulation (EU) 2022 / 1616 of the European Commission (EC) of September 15, 2022 on recycled plastic materials and articles in contact with foodstuffs.

[0023] The method allows the use of elevated temperatures and pressures, which means that the transport mechanism for removing the non-solvent carrying impurities is accelerated. The reduction in the number of steps means that the method takes less time to carry out and therefore requires less solvent to achieve the removal of impurities from the impure extrudable material. The substantially uniform mixing of the non-solvent with the impure extrudable material allows for fast processing times, and therefore requires a small amount of non-solvent to remove impurities from the impure extrudable material. The method of extruding recycled polymers requires only a small amount of non-solvent and therefore has economic advantages as well as ecological advantages.

[0024] The non-solvent with impurities is discharged from the extruder in a gaseous state.

[0025] The nonsolvent forms a mixture with the impurities, and in one aspect forms an azeotropic mixture with the impurities.

[0026] The non-solvent is selected from at least one of water, a mixture of water, a base, an ester, an alcohol, an ether, an alkane or a ketone. The alcohol is, for example, selected from methanol, ethanol or isopropanol. The base is at least one of ammonia or pyridine.

[0027] In one aspect, the non-solvent is a mixture of water and carbon dioxide, the concentration of carbon dioxide in water being 10% to 50% by weight. The surprising result is that water is able to remove impurities, since the prior art has shown that the use of water in recycled plastics does not allow water to be sufficiently finely dispersed in the recycled plastics to allow this removal. Carbon dioxide acts as a catalyst. Compared to alternative acidic or basic catalysts, the use of carbon dioxide is more ecologically advantageous because carbon dioxide is easily removed from the melt. In addition, carbon dioxide does not leave residues in the extruded plastics, which can cause problems when the products made from the extruded plastics come into contact with living agents.

[0028] In one aspect, the impurity is an impurity having a molecular weight of up to 500 g / mol and in one aspect up to 160 g / mol. Examples of impurities are, for example, one or more of: carboxylic acids, aldehydes, terpenes, aromatic hydrocarbons, olefins, alkanes, nitrogen-based compounds, phosphorus-based compounds, sulfur-based compounds, or mixtures thereof.

[0029] In one non-limiting aspect, the impure extrudable material is passed through a melt filter before the non-solvent is injected. The impure extrudable material may also be passed through a melt filter after the non-solvent is injected. In other aspects, two melt filters may be used, one before and one after the non-solvent is injected.

[0030] The mixing of the nonsolvent with the impure extrudable material is carried out, for example, at a temperature of 110 to 330° C. and a pressure of 2 to 300 bar.

[0031] The method further comprises the steps of outputting the recycled polymer into water to cool the recycled polymer and subsequently or simultaneously cutting the polymer to form polymer particles.

[0032] Also disclosed is an apparatus for removing impurities from an impure extrudable material, the apparatus comprising an injector for injecting a liquid non-solvent into the impure extrudable material, a mixing element for substantially uniformly mixing the non-solvent with the impure extrudable material, and an output device for outputting gaseous impurities from the apparatus.

[0033] The mixing element comprises a screw device in a housing. The mixing element also comprises one of a single screw or multiple screws (eg, a twin screw).

[0034] The screw apparatus also includes one of a kneading block or a toothed disk.

[0035] The apparatus also includes a heating device for heating the impure extrudable material.

[0036] Also disclosed is a recycled polymer comprising a polyolefin and impurities, wherein each impurity is substantially uniformly distributed in the recycled polymer, and wherein the concentration of each impurity in the recycled polymer is at most 10 ppm by weight, and in other aspects at most 5 ppm by weight.

[0037] The polyolefin includes polyethylene or polypropylene.

[0038] Recycled polymers have low odor properties.

[0039] Also disclosed is the use of recycled polymers, for example in consumer packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A view showing an apparatus for removing impurities from an impure extrudable material is shown.

[0041] Figure 2 Aspects of the apparatus are shown having a screw device within a housing.

[0042] Figure 3 An enlarged view of a mixing element including a kneading block is shown.

[0043] Figure 4 An enlarged view of a mixing element including a toothed disc is shown.

[0044] Figure 5 A flow chart describing a method of extruding a recycled polymer from an impure extrudable material is shown. DETAILED DESCRIPTION

[0045] The present invention will now be described based on the accompanying drawings. It will be understood that the embodiments and aspects of the present invention described herein are only examples and do not limit the scope of protection of the claims in any way. The present invention is defined by the claims and their equivalents. It will be understood that the features of one aspect or embodiment of the present invention may be combined with the features of one or more different aspects and / or embodiments of the present invention.

[0046] Figure 1 An example of an apparatus 10 for removing impurities 20 from an impure extrudable material 30 is shown. The apparatus 10 may be, for example, an extruder. The apparatus 10 includes a hopper 15, a housing 62, and a material outlet 90. The impure extrudable material 30 is within the housing 62, and an injector 45 connected to the housing 62 is capable of injecting a liquid non-solvent 50 into the impure extrudable material 30. A heating element 80 is present in the apparatus 10 to heat the impure extrudable material 30.

[0047] The housing 62 encloses the mixing element 60. The mixing element 60 enables the non-solvent 50 to be mixed with the impure extrudable material 30 in a substantially uniform manner. The mixing element 60 may be Figure 2 The screw device 61 shown in the figure can be a single screw or a twin screw. The mixing element 60 can also be Figure 3 The kneading block 63 shown in FIG. Figure 4 The toothed disc 64 is shown in FIG.

[0048] The apparatus 10 further includes an output device 70 for outputting gaseous impurities 20 from the apparatus 10. The recycled polymer 100 is output from the material outlet 90 into a water bath 110 filled with water. The recycled polymer 100 is output into the water bath 110 to cool the output recycled polymer 100. While the recycled polymer 100 is output into the water bath 110 or after it is cooled in the water bath 110, the recycled polymer 100 is cut into particles or pellets.

[0049] The apparatus 10 may also include a melt filter 40. In one aspect, the melt filter 40 is placed before the injector 45 and is used to remove impurities contained in the impure extrudable material 30. The impurities may be solid contaminants such as particulates, unconverted polymer, carbonized polymer, agglomerated additives, and debris such as metal particles, dust or dirt.

[0050] In other aspects, melt filter 40 is positioned after (ie, downstream of) injector 45 .

[0051] In the present invention, the term “impure extrudable material” means a polymer material that can be heated and extruded. The extrudable material 30 provided to the material inlet 15 contains impurities 20 at a high concentration.

[0052] In one non-limiting example, the impure extrudable material comprises the impurity 20 at a concentration of at least 70 ppm. In other examples, the impure extrudable material 30 comprises the impurity 20 at a concentration of 60 ppm and higher.

[0053] In one aspect, the impure extrudable material 30 comprises a polyolefin. The polyolefin is polyethylene (PE), polypropylene (PP), or a mixture thereof. The impure extrudable material 30 may be low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polymethylpentene (PMP), polyisobutylene (PIB), polybutylene (PB), or a mixture thereof. The impure extrudable material 30 may be polyethylene terephthalate (PET), polyamide (PA) such as copolyamide 6 / 66 (PA6 / 66), polylactic acid (PLA), or cellulose acetate (CA).

[0054] The impure extrudable material 30 originates, for example, from packaging materials. The impure extrudable material 30 originates, for example, from post-consumer packaging materials, such as food packaging, pharmaceuticals, cosmetics and oral care materials. In a further example, the impure extrudable material 30 is a recycled material, for example from a garbage collection system, a so-called "yellow bag" (German packaging collection system "gelberSack"), a sorting center or a paper mill. The recycled material may be subjected to a sorting and separation step, for example by air separation, a defibration technique, and / or a washing step, for example with water or lye, before the recycled polymer is extruded from the impure extrudable material.

[0055] The term "low molecular impurity" used in the present invention means a molecule with a molecular weight of up to 500 g / mol. In one example, the low molecular impurity 20 has a molecular weight of 40 to 160 g / mol, and in other examples, the low molecular impurity 20 has a molecular weight of 60 to 130 g / mol.

[0056] In one aspect, impurity 20 is one or more of the following: carboxylic acids, aldehydes, terpenes, aromatic hydrocarbons, olefins, alkanes, nitrogen-based compounds, phosphorus-based compounds, sulfur-based compounds, or mixtures thereof. In one example, impurity 20 includes limonene, N-ethylformamide, N,N-dimethylguanidine, N-methoxymethyl-N-methylformamide, hexadecane, tetradecanoic acid, octadecane, hexadecanoic acid, eicosane, cis-13-octadecenoic acid, octadecanoic acid, docosane, tricosane, tetracosane, pentacosane, bis(2-ethylhexyl)phthalate, hexacosane, heptacosane, 1,3-phthalic acid, bis(2-ethylhexyl) ester, nonadecane, and mixtures thereof.

[0057] The term "non-solvent" includes compounds that cannot dissolve the impure extrudable material 30. Examples of non-solvent 50 include water, water mixtures, bases, esters, ethers, alkanes, alcohols or ketones. Bases are, for example, ammonia or pyridine. Esters are, for example, ethyl acetate. Alcohols include methanol, ethanol or isopropanol. Ketones are, for example, acetone.

[0058] The recycled polymer 100 has mechanical and organoleptic properties. The recycled polymer 100 has low odor properties.

[0059] Removal of impurities 20 from the impure extrudable material 30 results in the recycled polymer 100 having good mechanical properties such as toughness, elongation at break and strength. This is due to the removal of structural defects in the recycled polymer.

[0060] Figure 5A method of extruding a recycled polymer 100 from an impure extrudable material 30 is shown. In step 100, the impure extrudable material 30 is fed into a housing 62 including a mixing element 60 through a hopper 15 and melted using a heating device 80. The rotation of the mixing element 60 causes the impure extrudable material 30 in a molten state to be forwarded through the device 10. Due to the work done on the impure extrudable material 30 by the rotation of the mixing element 60 and the heating of the housing 62 by the heating device 80, the temperature inside the housing 62 increases. For example, the temperature inside the housing is 110°C to 330°C, and in other aspects is 200°C to 230°C. For example, the temperature inside the housing is 130°C to 230°C, 180°C to 230°C, 250°C to 290°C, or 250°C to 310°C. The increase in temperature causes the pressure inside the housing 62 to increase. The pressure inside the housing 62 can be, for example, 2 to 300 bar. The pressure inside the housing 62 depends on the nature of the impure extrudable material 30, the nature of the non-solvent 50, the temperature inside the housing 62 and the rotational speed of the mixing element 60. The pressure is selected so that the non-solvent 50 does not evaporate but remains liquid in the housing 62. The elevated temperature and pressure in the device enable the process of extruding the recycled polymer 100 from the impure extrudable material 30 to be accelerated. The term "high pressure" means that the pressure must be applied at the corresponding processing temperature to prevent the evaporation of the non-solvent 50 in the injection zone.

[0061] In step S110, a non-solvent 50 in a liquid state is injected into the device 10. The non-solvent 50 is injected into the device 10 at a pressure such that the pressure in the housing 62 of the device 10 is higher than the vapor pressure of the non-solvent. Under such pressure in the device 10, the non-solvent 50 is in a liquid state in the housing 62, preventing the formation of bubbles in the device 10 and enabling the non-solvent 50 and the impure extrudable material 30 to be uniformly mixed. In step 120, the non-solvent 50 and the impure extrudable material 30 are substantially uniformly mixed together by the mixing element 60 to form a dispersion 55 of the non-solvent 50 and the impure extrudable material 30. In one aspect of the present invention, the non-solvent 50 and the impurity 20 form an azeotropic mixture. Because the diffusion length in a uniform mixture is small, the uniform mixing of the non-solvent 50 and the impure extrudable material 30 enables the impurity 20 to be better absorbed in the non-solvent 50, and thus facilitates the removal of the impurity 20 from the impure extrudable material 30.

[0062] At the output device 70, the pressure in the housing 62 is reduced, so that the impurities 20 in the non-solvent 50 can be converted from a liquid state to a gaseous state. In step 130, the gaseous impurities 20 are output from the device 10 at the output device 70. In one aspect, the gaseous impurities 20 are output from the device 10 in a vacuum. Such a (partial) vacuum is generated, for example, by using a water ring vacuum pump. Outputting the gaseous impurities 20 in a vacuum enables the impurities 20 in the impure extrudable material 30 to be better extracted into the non-solvent 50. In step 150, the recycled polymer 100 is driven through the material outlet 90 to be output to the water bath 110 for cooling. At the material outlet 90, the recycled polymer 100 is cut into particles.

[0063] The term "azeotropic mixture" means a mixture in which the mole fraction of all components in the liquid state is equal to the mole fraction of all components in the vapor state. The impure extrudable material 30 containing the impurity 20 is heated in the device 10. The injection of the non-solvent 50 enables the formation of an azeotropic mixture of the impurity 20 and the non-solvent 50. The non-solvent 50 is injected into the device 10 at a pressure of, for example, 3-90 bar, and in one aspect 50 to 80 bar. The temperature of the mixture in the device 10 means that the impurity 20 will be absorbed into the non-solvent 50. In step 130, the impurity 20 is then removed from the impure extrudable polymer 30 by the output device 70.

[0064] In one example, the mixing element 60 has a low channel depth or low pitch.

[0065] In one embodiment, in step 105 , the impure extrudable material 30 is passed through a melt filter 40 before the non-solvent 50 is injected into the apparatus 10 .

[0066] Example of Processing Conditions for Extruding Recycled Polymers

[0067] The compositions listed below are merely examples of suitable formulations and do not limit the invention (all percentages are by weight):

[0068] The concentrations of the following components of the impure extrudable material were measured by differential scanning calorimetry (DSC). The concentrations of impurities were measured by gas chromatography-mass spectrometry (GC-MS). The pressure in the syringe was measured by a pressure gauge.

[0069] Composition 1

[0070] Composition 2

[0071] Composition 3

[0072] Composition 4

[0073] Composition 5

[0074] Composition 6

[0075] The examples listed below are merely examples of suitable processing conditions for extruding recycled polymers from impure extrudable materials and are not intended to limit the invention.Examples 1 to 5 illustrate different impure extrudable materials that can be processed to obtain recycled polymers. Example 1

[0076] The impure extrudable material has the shape of colored flakes, coming from post-consumer packaging material. The colored flakes have, for example, irregular geometry, a thickness of less than 50 μm. The concentration of impurities in the impure extrudable material is 1.5%. The composition of the non-solvent injected into the device is 43% water and 57% pyridine. The pressure in the injector is 21 bar. At the end of the process, the concentration of impurities in the recycled polymer is < 0.1%. Example 2

[0077] The impure extrudable material has the shape of colored flakes and comes from post-consumer packaging material. The concentration of impurities in the impure extrudable material is 1.2%. The composition of the non-solvent injected into the device is ethyl acetate. The pressure in the injector is 36 bar. At the end of the process, the concentration of impurities in the recycled polymer is < 0.05%. Example 3

[0078] The impure extrudable material has the shape of colorless flakes and comes from post-industrial recyclables. The concentration of impurities in the impure extrudable material is 1.1%. The composition of the non-solvent injected into the device is isopropanol. The pressure in the injector is 28 bar. At the end of the process, the concentration of impurities in the recycled polymer is < 0.01%. Example 4

[0079] The impure extrudable material originates from film waste. The impure extrudable material has, for example, a uniform geometry, a thickness greater than 50 μm. The concentration of impurities in the impure extrudable material is 1.5%. The composition of the non-solvent in the injection device is dioxane. The pressure in the injector is 72 bar. At the end of the process, the concentration of impurities in the recycled polymer is < 0.1%. Example 5

[0080] The impure extrudable material originated from the transfer film. The concentration of impurities in the impure extrudable material was 1.2%. The composition of the non-solvent injected into the device was cyclohexane. The pressure in the injector was 27 bar. At the end of the process, the concentration of impurities in the recycled polymer was < 0.1%. Example 6

[0081] The impure extrudable material originated from fiber recyclate. The concentration of impurities in the impure extrudable material was 1.2%. The composition of the non-solvent injected into the device was water. The pressure in the injector was 76 bar. At the end of the process, the concentration of impurities in the recycled polymer was < 0.05%.

[0082] Reference mark

[0083] 10 Installation

[0084] 15 Hopper

[0085] 20 Impurities

[0086] 30 Impure extrudable materials

[0087] 40 melt filter

[0088] 45 Syringes

[0089] 50 non-solvent

[0090] 55 Dispersion

[0091] 57 Polymer melt

[0092] 60 Mixing elements

[0093] 61 screw equipment

[0094] 62 Shell

[0095] 63 kneading block

[0096] 64 toothed disc

[0097] 65 single screw

[0098] 66 multi-screw

[0099] 70 Output devices

[0100] 80 Heating equipment

[0101] 90 Material Export

[0102] 100% recycled polymer

[0103] 110 Water bath

Claims

1. A method for extruding a recycled polymer (100) from an impure extrudable material (30), comprising the steps of: Injecting (S110) a liquid non-solvent (50) into the device (10); mixing the non-solvent (50) and the impure extrudable material (30) substantially uniformly (S120) and thereby forming a dispersion (55) of the non-solvent (50) and the impure extrudable material (30); Gaseous impurities (20) are output (S130) from the device (10).

2. The method according to claim 1, wherein the non-solvent (50) forms an azeotropic mixture with the impurity (20).

3. The method according to claim 1 or 2, wherein the residual concentration of impurities in the recycled polymer (100) is lower than 10 ppm.

4. The method according to claims 1 to 3, wherein the non-solvent (50) is selected from at least one of the following: water, a mixture of water, a base, an ester, an alcohol, an ether, an alkane or a ketone.

5. The method according to claims 1 to 4, wherein the base is at least one of ammonia or pyridine.

6. The method according to claims 1 to 5, wherein the non-solvent (50) is selected from an alcohol selected from methanol, ethanol or isopropanol.

7. The method according to claims 1 to 4, wherein the non-solvent (50) is a mixture of water and carbon dioxide, preferably a mixture of carbon dioxide in water at a concentration of 10% to 50% by weight.

8. The method according to any of the preceding claims, wherein the impurity (20) has a molecular weight of at most 500 g / mol, preferably 160 g / mol.

9. The method according to any one of the preceding claims, wherein the impurities (20) are selected from one or more of the following: carboxylic acids, aldehydes, terpenes, aromatic hydrocarbons, olefins, alkanes, nitrogen-based compounds, phosphorus-based compounds, sulfur-based compounds or mixtures thereof.

10. The method according to any one of the preceding claims, wherein before the injection (S110) a step of passing (S105) the impure extrudable material (30) through a melt filter (40) is performed.

11. The method according to any one of the preceding claims, wherein the mixing (S120) of the non-solvent (50) and the impure extrudable material (30) is performed at a temperature of 110°C to 330°C.

12. The method according to any one of the preceding claims, wherein the mixing (S120) of the non-solvent (50) and the impure extrudable material (30) is performed at a pressure of 2 to 300 bar.

13. An apparatus (10) for removing impurities (20) from an impure extrudable material (30), comprising: a syringe (45) for injecting a liquid non-solvent (50) into the impure extrudable material (30); a mixing element (60) for substantially uniformly mixing the non-solvent (50) with the impure extrudable material (30); An output device (70) is provided for outputting the impurities (20) in a gaseous state from the device (10).

14. The device (10) according to claim 13, wherein the non-solvent (50) is selected from at least one of the following: water, a mixture of water, a base, an ester, an alcohol, an ether, an alkane or a ketone.

15. The device (10) according to claim 13 or 14, wherein the base is at least one of ammonia or pyridine.

16. The device (10) according to claims 13 to 15, wherein the non-solvent (50) is selected from an alcohol selected from methanol, ethanol or isopropanol.

17. The device (10) according to claims 13 to 16, wherein the impurity (20) has a molecular weight of at most 500 g / mol, preferably 160 g / mol.

18. The device (10) according to claims 13 to 17, wherein the impurities (20) are selected from one or more of the following: carboxylic acids, aldehydes, terpenes, aromatic hydrocarbons, olefins, alkanes, nitrogen-based compounds, phosphorus-based compounds, sulfur-based compounds or mixtures thereof.

19. Apparatus (10) according to claims 13 to 18, wherein the mixing element (60) comprises a screw device (61) in a housing (62).

20. The device (10) according to claims 13 to 19, wherein the mixing element (60) comprises one of a single screw (65) or multiple screws (66).

21. The apparatus (10) according to claims 13 to 20, wherein the screw device (61) comprises one of a kneading block or a toothed disc.

22. A recycled polymer (100) comprising a polyolefin and impurities (20), wherein each of the impurities (20) is substantially uniformly distributed in the recycled polymer (100), and wherein the concentration of each of the impurities (20) in the recycled polymer (100) is at most 10 ppm by weight.

23. The recycled polymer (100) according to claim 22, wherein the concentration of each of the impurities (20) in the recycled polymer (100) is at most 5 ppm by weight.

24. The recycled polymer (100) according to claim 22 or 23, wherein the impurities (20) have a molecular weight of at most 500 g / mol, preferably 160 g / mol.

25. The recycled polymer (100) according to claims 22 to 24, wherein the impurities (20) are selected from one or more of the following: carboxylic acids, aldehydes, terpenes, aromatic hydrocarbons, olefins, alkanes, nitrogen-based compounds, phosphorus-based compounds, sulfur-based compounds or mixtures thereof.

26. The recycled polymer (100) according to claims 22 to 25, wherein the polyolefin comprises polyethylene or polypropylene.

27. The recycled polymer (100) according to claims 22 to 26, having low odor properties.

28. Use of recycled polymer (100) according to claims 22 to 27 in consumer packaging.

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