Method for purifying regenerated polymer

Abstract

Embodiments relate to methods for purifying regenerated polymers.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to polymers, and more specifically, to methods for purifying recycled polymers. BACKGROUND

[0002] The demand for polymers worldwide is currently high; over 100 million tons of polyethylene and 80 million tons of polypropylene were consumed in 2020. This demand is expected to further increase and is occurring at a time of increasing demand to limit the environmental impact of plastics. The reuse or recycling of plastic waste is advantageous, not only to limit the amount that is irreversibly released into the environment, but also to reduce the amount of new polymer or virgin polymer produced through high energy and CO2-intensive processes.

[0003] Polymers recycled mechanically are obtained by collecting post-consumer or post-industrial recycled material and sorting it into roughly homogeneous polymer streams, which are washed with aqueous and / or caustic solutions before reprocessing into pellets of recycled polymers. However, the reprocessed pellets are often still contaminated with unwanted impurities, including organoleptic compounds, colorants, gels, heavy metals, and plasticizers added to the product for specific applications, as well as other polymers that were not removed during the mechanical sorting process. These impurities cause the physical properties of the recycled polymers to degrade, which limits their reuse, and as a result, they are often downcycled to a limited number of less demanding applications, while ubiquitous sources of plastic waste, such as multilayer packaging and films, are completely excluded because the current mechanical recycling methods are unable to sort the polymers contained therein.

[0004] Solvent-based methods have been developed to address the limitations of mechanical recycling, aiming to remove at least some of these impurities to produce purer, regenerated polymers with improved physical properties. The range of potential impurities to be removed can be matched with various solvent-based process operations, including but not limited to dissolution, crystallization, sedimentation, centrifugation, filtration, adsorption, and extraction, or combinations of each operation tailored to remove specific impurities. While capable of producing purified polymers with properties close to those of natural materials, solvent-based methods introduce higher costs and additional process risks. The more complex processes involving solvents under a wide range of operating conditions require higher capital equipment, energy, and other operating costs compared to mechanical recycling, and introduce complexities such as scaling and clogging, which can further increase costs and potentially render the entire process unfeasible. These problems are exacerbated by the increasing variability of polymer-containing streams to be recycled; large-scale recycling of such variable streams is necessary to significantly increase the proportion of polymers recycled globally. Among these challenges, purified regenerated polymers must remain economically competitive with natural materials. Clearly, carefully designed and innovative process combinations are necessary for new solvent-assisted methods to purify a wider range of operationally feasible and cost-effective regenerated polymer sources. Summary of the Invention

[0005] This disclosure provides a method for purifying regenerated polymers. An example method includes: transferring the regenerated polymer to a polymer dissolving container, wherein the regenerated polymer comprises a solid; selectively dissolving the solid regenerated polymer in the polymer dissolving container with a solvent to prepare a polymer dissolving container composition, wherein the polymer dissolving container has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar; transferring the polymer dissolving container composition to a solid / liquid separation container to remove a first insoluble contaminant and prepare a solid / liquid separation container composition, wherein the solid / liquid separation container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar, wherein the solid / liquid separation container includes a filtration container, an adsorption separation container, or both; transferring the solid / liquid separation container composition to an extraction container to remove a first target portion of the solvent and a second soluble contaminant to prepare an extraction container composition, wherein the extraction container has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar; and transferring the extraction container composition to a polymer concentration container to remove a second target portion of the solvent and a third soluble contaminant to prepare a purified regenerated polymer.

[0006] Another example method includes: transferring a regenerated polymer to a polymer dissolving container, wherein the regenerated polymer comprises a solid; selectively dissolving the solid regenerated polymer in the polymer dissolving container with a solvent to prepare a polymer dissolving container composition, wherein the polymer dissolving container has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar; transferring the polymer dissolving container composition to a filtration container to remove a first insoluble contaminant and to prepare a filtration container composition, wherein the filtration container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar; transferring the filtration container composition to an adsorption separation container to remove a first soluble contaminant and to prepare an adsorption separation container composition, wherein the adsorption separation container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar; and transferring the adsorption separation container composition to an extraction container to remove a first target portion of the solvent and a second soluble contaminant to prepare an extraction container composition, wherein the extraction container has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar; and transferring the extraction container composition to a polymer concentration container to remove a second target portion of the solvent and a third soluble contaminant to prepare a purified regenerated polymer.

[0007] The foregoing description of this invention is not intended to describe every disclosed embodiment or every implementation thereof. The following description illustrates exemplary embodiments in more detail. Throughout this application, guidance is provided by a list of examples, which may be used in various combinations. In each case, the enumerated list serves only as a representative group and should not be construed as an exclusive list. Attached Figure Description

[0008] Figure 1 Examples of a system as part of one or more embodiments of this disclosure are illustrated.

[0009] Figure 2 Examples of a system as part of one or more embodiments of this disclosure are illustrated. Detailed Implementation

[0010] This document discloses a method for purifying regenerated polymers. Advantageously, the method disclosed herein can provide improved contaminant removal efficiency compared to other polymer purification processes, can utilize a wide range of solid polymer feedstocks, can provide reduced scaling compared to other polymer purification processes, and / or can provide purified regenerated polymers with a variety of properties desired for various applications, such as improved (e.g., lower) residual solvent content, improved (e.g., less) odor, and / or improved (e.g., less) color. The method for purifying regenerated polymers disclosed herein may include: transferring the regenerated polymer to a polymer dissolving vessel, wherein the regenerated polymer comprises a solid; selectively dissolving the solid regenerated polymer in the polymer dissolving vessel with a solvent to prepare a polymer dissolving vessel composition, wherein the polymer dissolving vessel has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar; transferring the polymer dissolving vessel composition to a filter vessel to remove a first insoluble contaminant and prepare a filter vessel composition, wherein the filter vessel has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar; and assembling the filter vessel. The process involves transferring the solvent to an adsorption separation vessel to remove a first soluble contaminant and prepare an adsorption separation vessel composition, wherein the adsorption separation vessel has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar; transferring the adsorption separation vessel composition to an extraction vessel to remove a first target fraction of the solvent and a second soluble contaminant, to prepare an extraction vessel composition, wherein the extraction vessel has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove a second target fraction of the solvent and a third soluble contaminant, to prepare a purified regenerated polymer. One or more embodiments specify that a solid medium, as further discussed herein, may be added to the filtration vessel, for example, such that the solid medium provides a filter aid. The vessels mentioned herein can be devices connected in series, in parallel, or in combinations thereof. Embodiments specify that the methods disclosed herein for purifying regenerated polymers can be continuous processes, batch processes, or combinations thereof.

[0011] Surprisingly, it has been found that selectively dissolving the regenerated polymer under the conditions described herein (e.g., temperature and pressure) as a first process step, such as prior to filtration, adsorption, and / or extraction, reduces process fouling / clogging and can provide a more consistent and / or improved composition of the purified regenerated polymer. For example, performing a selective dissolution step under conditions discussed herein (e.g., relatively high pressures in the range of 20 to 120 bar, 20 to 100 bar, 30 to 100 bar, or greater than 30 to 100 bar) can help minimize or prevent the formation of a second polymer liquid phase. For example, in some embodiments, the polymer dissolution container composition in the polymer dissolution container can be maintained (e.g., by operating under the pressures described herein) above the cloud point of the polymer dissolution container composition (e.g., above the cloud point of the polyurethane included in the polymer dissolution container composition) to prevent the formation of a second polymer liquid phase (e.g., a liquid phase comprising primarily polypropylene or other polymers besides polyethylene) in the polymer dissolution container composition. That is, the polymer dissolving container composition in the polymer dissolving container can be maintained above the cloud point of each of the one or more different types of regenerated polymers (e.g., polyethylene and / or polypropylene, etc.) included (e.g., mainly included) in the polymer dissolving container composition to minimize the formation of a second polymer liquid phase. As discussed herein, if not operated at higher relative pressures (i.e., above the cloud points of the two regenerated polymers), one or both of these polymers may separate into concentrated polymer phases. In some cases (i.e., solution pressures between the cloud points of the pure components), a regenerated polymer separates into a first phase and a second polymer with much less solvent. The polyethylene-solvent phase can be heavier than the polypropylene-solvent phase. This density difference between the two phases can become smaller at lower temperatures. This undesirable phase separation (e.g., when operating at lower pressures) can affect the quality of the purified regenerated polymer and cause process problems (e.g., leading to increased operational difficulty and / or energy consumption associated with the transport or pumping of the polymer dissolving container composition).

[0012] As used herein, the term "cloud point" refers to the temperature at which a substance (typically a polymer solution) undergoes a phase transition from a clear solution to a cloudy or hazy appearance due to the formation of a second polymeric liquid phase. For the purposes of this article, VLXE is used. ®Software and perturbed-chain statistical associative fluid theory (PC-SAFT) equation of state are used to simulate the cloud point using publicly available parameters, such as those obtained from: Tumakaka, Feelly, Joachim Gross, and Gabriele Sadowski. "Modeling of polymer phase equilibria using Perturbed-Chain SAFT." Fluid PhaseEquilibria 194 (2002): 541-551 (e.g., PC-SAFT pure component parameters for polyethylene and polypropylene); and Gross, J., & Sadowski, G. (2001). Perturbed-chain SAFT: An equation of state based on a perturbation theory for chain molecules. Industrial & engineering chemistry research, 40(4), 1244-1260 (e.g., PC-SAFT pure component parameters for n-pentane).

[0013] As used herein, the term "recycled polymer" refers to a polymer that has been used for a prior purpose and is then recycled for further processing. For example, "recycled polymer" can refer to polymers recovered from post-consumer materials as defined in ISO 14021, polymers recovered from pre-consumer materials as defined in ISO 14021, and combinations thereof. The general term "post-consumer material" includes blends of polymers recovered from materials generated by households or commercial, industrial, and institutional facilities in their role as end-users of materials that can no longer be used for their intended purpose. The general term "post-consumer material" also includes blends of polymers recovered from returned materials from the distribution chain. The general term "pre-consumer material" includes blends of polymers recovered from materials transferred from waste streams during the manufacturing process. The general term "pre-consumer material" does not include the reuse of materials generated in the process and capable of being recycled in the same process in which they are generated, such as reprocessing, regrinding, or disposal. Recycled polymers can include polymers or blends of polymers recovered from post-consumer materials, pre-consumer materials, or combinations thereof.

[0014] Recycled polymers are different from natural polymers. "Natural polymers" refers to polymers that can be characterized as "primary (natural) raw materials" as defined by ISO 18604. The term natural polymers can include polymers that have never been processed into any form of end-use product. Natural polymers may also be referred to by various other terms.

[0015] Regenerated polymers can be collected and processed prior to purification using the methods disclosed herein. For example, for pre-purification, the regenerated polymer can be shredded, washed, subjected to metal reduction (e.g., removal), density separation, dried, and / or sorted.

[0016] Recycled polymers can be homopolymers, copolymers, or combinations thereof. Examples of recycled polymers include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, vinyl polymers such as polyvinyl chloride, acrylonitrile, butadiene, and styrene homopolymers and interpolymers, polyesters such as polyethylene terephthalate and poly(bisphenol A carbonate), polyamides such as nylon 66, polycarbonates such as poly(bisphenol A carbonate), acrylics such as poly(methyl methacrylate), fluorocarbon polymers, polyethers, polysaccharides, silicones such as poly(dimethylsiloxane), thermoplastic elastomers such as ethylene propylene rubber, etc.

[0017] Regenerated polymers can include a variety of contaminants. Examples of contaminants include cellulose fibers, rubbers such as nitrile rubber, fillers such as calcium carbonate, pigments, dyes, processing aids, stabilizing additives and their degradation products, inks, adhesives, dirt and rocks, crosslinked polymers and other performance additives such as plasticizers, slip agents and anti-caking agents, as well as other contaminants. Examples of contaminants include sensory compounds such as aldehydes, ketones, esters, organic pigments such as diazo pigments (yellow), phthalocyanine green, phthalocyanine blue, lithol (red), inorganic pigments such as titanium dioxide (white), carbon black, cadmium selenide (red), molybdate orange, lead chromate (yellow), glyceryl monostearate and PEG (antistatic agents), erucamide and oleamide (slip agents), hindered phenols and phosphites as antioxidants, polyisobutylene as an adhesive, hindered amines as UV stabilizers, as well as calcium carbonate, talc and glass fibers (fillers), and other contaminants.

[0018] Embodiments of this disclosure specify that the regenerated polymer is soluble in a solvent. As used herein, the terms "soluble," "soluble," and "dissolved" refer to the association of molecules or ions of the solute (e.g., the regenerated polymer) with solvent molecules, i.e., solvation, which results in the incorporation of the solute into the solvent. The stability of a solute dissolved in a solvent depends strongly on intermolecular interactions between solute molecules, between solvent molecules, and between each other. The favorability of a solute-solvent pair can be estimated by calculating the relevant Hildebrand or Hansen solubility parameters; both such methods are examples applicable to both the polymer and the solvent. The thermodynamic stability of the mixture can be evaluated by the following equation: ΔGmix = ΔHmix - TΔSmix; where ΔGmix is ​​the Gibbs free energy change of the solute-solvent mixture, ΔHmix is ​​the enthalpy change of the mixture, T is the absolute temperature, and ΔSmix is ​​the entropy of the mixture. If the Gibbs free energy change of the solute-solvent mixture is negative and minimized, then the dissolved solute in the solvent is stable at a given temperature and pressure.

[0019] As used herein, the terms “insoluble,” “non-soluble,” and “undissolved” are used interchangeably.

[0020] Figure 1 An example of a portion of a purification system 102 according to one or more embodiments of the present disclosure is illustrated. The purification system 102 may include a polymer dissolving container 104. As used herein, “a,” “an,” and “a plurality” can refer to one or more of something. For example, a polymer dissolving container can refer to one or more polymer dissolving containers, such as a series of containers, parallel containers, or combinations thereof. As described herein, one or more embodiments specify that, as Figure 1 The combination of filter container 112 and adsorption separation container 118 shown can be used, for example, as a solid / liquid separation container 111. In such embodiments, each of the filter container 112 and adsorption separation container 118 may be present, or alternatively, the filter container 112 or adsorption separation container 118 may be eliminated (not present).

[0021] The figures in this document follow a numbering rule in which the first one or more digits correspond to the figure number, and the remaining digits identify elements or components in the figure. Similar elements or components between different figures can be identified by using similar digits. For example, 104 could represent... Figure 1 The component "04" in the text, and similar components can be found in Figure 2 The symbol is represented as 204. Multiple similar elements or components in a figure may include letters to indicate that the elements or components are similar. For example, in... Figure 2 In Chinese, "204A" is similar to "204B", and both are similar to Figure 1104 in the middle.

[0022] The polymer dissolving container 104 can be made of various materials and has different shapes and / or sizes for various applications. As used herein, the term "container" refers to a tank, tube, separator, decanter, column, heat exchanger, extruder, and / or other fluid handling hardware. The polymer dissolving container 104 may include many known components, such as agitators and / or heating coils. The polymer dissolving container 104 may include multiple inlets and / or outlets. For example, the polymer dissolving container 104 may include an inlet 106. The inlet 106 can be used to transfer regenerated polymer into the polymer dissolving container 104.

[0023] The implementation scheme specifies that the regenerated polymer transferred to the polymer dissolution container 104 is solid, for example, in a solid rather than liquid state. The solid regenerated polymer can be crystalline, semi-crystalline, amorphous, or a combination thereof. Transferring the solid regenerated polymer to the polymer dissolution container 104 can reduce the costs associated with melting the regenerated polymer transferred to the polymer dissolution container 104, can reduce the processing complexity associated with melting the regenerated polymer transferred to the polymer dissolution container 104, and / or can facilitate the selective dissolution of the transferred regenerated polymer in the polymer dissolution container 104.

[0024] Solid recycled polymers can have a variety of shapes and / or sizes. For example, solid recycled polymers can be fragments, spheres, cylinders, pellets, or combinations thereof, as well as other shapes. Solid recycled polymers can have an average diameter from 1 millimeter (mm) to 200 millimeters.

[0025] The polymer dissolving container 104 may include an inlet 108. The inlet 108 can be used to transfer solvent into the polymer dissolving container 104. Embodiments specify that the solvent is maintained as a liquid within the polymer dissolving container 104, for example, using appropriate temperature and pressure.

[0026] The implementation scheme specifies that a solvent selectively dissolves a solid regenerated polymer transferred to a polymer dissolution container 104 to prepare a polymer dissolution container composition. In other words, the solvent selectively dissolves the solid regenerated polymer under the temperature and pressure of the polymer dissolution container 104. The solubility of the polymer in the solvent (e.g., for selective dissolution) can depend on the solvent / polymer interaction, the dissolution temperature, and the crystallinity of the polymer. For example, to dissolve a semi-crystalline polymer, the solvent can diffuse into the surface of the polymer, dissolving a portion of the semi-crystalline structure, causing the polymer to swell, and then the amorphous layer can be removed. The dissolution rate can depend on a variety of factors, including but not limited to: the crystallinity of the regenerated polymer, the speed of the agitator used, temperature, pressure, solid size, and / or solvent composition. Polymers with similar melting points and sizes can have significantly different dissolution rates. Multiple liquid phases can be formed when the dissolution temperature, pressure, and / or dissolution time are varied, and potentially, multiple polymers can be dissolved. However, the formation of multiple liquid polymer phases is undesirable because it can compromise the mechanical properties of the product and / or lead to process fouling.

[0027] Polymer dissolving container compositions may include solvents, dissolved regenerated polymers, and a number of soluble or insoluble contaminants. Soluble or insoluble contaminants include many of the aforementioned contaminants. Insoluble contaminants (e.g., insoluble pollutants) include pigments, cellulose fibers, calcium carbonate, talc, dirt, and adhesives, among other contaminants. Polymers other than selectively dissolved regenerated polymers may be insoluble or dissolved contaminants. However, as further discussed herein, polymers other than regenerated polymers can be purified in parallel processes.

[0028] Solvents can be selected based on the solid regenerated polymer to be selectively dissolved. In other words, different solvents can be used for different solid regenerated polymers. Examples of solvents include aliphatic, aromatic or cyclic, saturated or unsaturated hydrocarbons, alcohols, carboxylic acids, esters, ketones, amines, and halogenated solvents. One or more embodiments specify that the solvent is selected from ketones, alcohols, ethers, esters, alkenes, alkanes, and combinations thereof. One or more embodiments specify that the solvent is selected from acetone, methyl ethyl ketone, methanol, ethanol, propanol, isopropanol, dimethyl ether, diethyl ether, ethyl methyl ether, methyl acetate, ethyl acetate, ethylene, propylene, 1-butene, 2-butene, isobutene, pentene, cyclopentene, isomers of pentene, hexene, cyclohexene, 1-methyl-cyclopentene, isomers of hexene, heptane, cycloheptene, 1-methyl-1-cyclohexene, isomers of heptane, methane, ethane, propane, n-butane, isobutane, n-pentane, cyclopentane, isomers of pentane, n-hexane, cyclohexane, 1-methyl-1-cyclopentane, isomers of hexane, heptane, cycloheptane, 1-methyl-1-cyclohexane, dimethylcyclopentane, and isomers of heptane. One or more embodiments specify that the solvent is an alkane, such as a C3-C12 alkane, a C4-C10 alkane, a C5-C7 alkane, or a C5-C6 alkane. For example, one or more embodiments specify that the solid recycled polymer is polyethylene and the solvent is pentane.

[0029] One or more embodiments specify that the solvent has a boiling point from 25°C to 90°C. This includes all individual values ​​and sub-ranges from 25°C to 90°C; for example, the solvent may have a boiling point from a lower limit of 25°C, 28°C, or 30°C to an upper limit of 90°C, 80°C, or 70°C. In this document, "boiling point" refers to the boiling temperature at an absolute pressure of exactly 100 kPa (1 bar, 14.5 psia, 0.9869 atm), as determined by the International Union of Pure and Applied Chemistry (IUPAC). One or more embodiments specify the use of low-boiling-point solvents, for example, solvents having a boiling point from 25°C to 75°C. Using low-boiling-point solvents reduces residual solvent in the ultimately purified regenerated polymer.

[0030] As used herein, "solvent" refers to a single solvent, such as pentane, or a combination of solvents, such as a combination of pentane and diethyl ether. Embodiments specify that when using a combination of solvents, the boiling points of each solvent in the combination differ from each other by within 20°C. One or more embodiments specify that when using a combination of solvents, the boiling points of each solvent in the combination differ from each other by within 15°C, 10°C, or 5°C. Solvents may be added at various points in the process. For example, solvents may be added to polymer dissolution vessel 104, solid / liquid separation vessel 111 (e.g., including filtration vessel 112 and / or adsorption separation vessel 118), and / or extraction vessel 124. One or more embodiments specify that the single solvent used for selectively dissolving the solid regenerated polymer transferred to the polymer dissolution vessel is 100% by weight of the total weight of solvents used in the process. For example, when the solid regenerated polymer is polyethylene and the solvent (e.g., the single solvent) is pentane, one or more embodiments specify that only pentane is used, for example, without using other solvents.

[0031] Based on the total weight of the solid regenerated polymer and solvent transferred to the polymer dissolving vessel to prepare the polymer dissolving vessel composition, the solvent can be from 70 wt% to 95 wt%. This includes all individual values ​​and sub-ranges from 70 wt% to 95 wt%; for example, based on the total weight of the solid regenerated polymer and solvent transferred to the polymer dissolving vessel to prepare the polymer dissolving vessel composition, the solvent can be from a lower limit of 70 wt%, 80 wt%, 82 wt%, or 85 wt% to an upper limit of 95 wt%, 93 wt%, or 90 wt%.

[0032] Similarly, based on the total weight of the solid regenerated polymer and solvent transferred to the polymer dissolving container to prepare the polymer dissolving container composition, the solid regenerated polymer can be from 5 wt% to 30 wt%. This includes all individual values ​​and sub-ranges from 5 wt% to 30 wt%; for example, based on the total weight of the solid regenerated polymer and solvent transferred to the polymer dissolving container to prepare the polymer dissolving container composition, the solid regenerated polymer can be from a lower limit of 5 wt%, 7 wt%, or 10 wt% to an upper limit of 30 wt%, 25 wt%, 20 wt%, 18 wt%, or 15 wt%.

[0033] For various applications, the solid regenerated polymer transferred to the polymer dissolving container 104 may be in contact with the solvent within the polymer dissolving container for different times, such as different residence times. For example, the solid regenerated polymer transferred to the polymer dissolving container may have an average residence time of 0.01 hours to 3 hours within the polymer dissolving container. This includes all individual values ​​and sub-ranges from 0.01 hours to 3 hours; for example, the solid regenerated polymer transferred to the polymer dissolving container may have an average residence time of a lower limit of 0.01 hours, 0.05 hours, or 0.1 hours to a higher limit of 3 hours, 2 hours, or 0.5 hours within the polymer dissolving container.

[0034] The polymer dissolving container 104 can have a temperature from 70°C to 180°C, such as an operating temperature. Using a combination of a temperature from 70°C to 180°C and the pressure described herein, preferred solid recycled polymers can be selectively dissolved in a solvent, while other polymers remain suspended as solids in the solution. This includes all individual values ​​and sub-ranges from 70°C to 180°C; for example, the polymer dissolving container can have a lower limit of 70°C, 90°C, or 110°C to an upper limit of 180°C, 170°C, 160°C, or 140°C. One or more embodiments specify that the polymer dissolving container can have a temperature from 120°C to 170°C, for example, when the recycled polymer comprises polyethylene.

[0035] The polymer dissolving container 104 can have an absolute pressure of 20 bar to 120 bar, such as the operating pressure. Unless otherwise stated, the pressures reported herein are absolute pressures. Using pressures of 20 bar to 120 bar allows for the selective dissolution of solid regenerated polymers in a solvent, while the solvent remains liquid, for example, as opposed to other methods that may use lower pressures. This includes all individual values ​​and sub-ranges from 20 bar to 120 bar; for example, the polymer dissolving container can have a lower limit of 20 bar, 30 bar, or 35 bar to an upper limit of 120 bar, 110 bar, 100 bar, 90 bar, or 80 bar. For example, in some embodiments, the operating pressure of the polymer dissolving container 104 can be greater than 30 bar, for example, in the range of greater than 30 bar to 120 bar.

[0036] The polymer dissolving container 104 may include an outlet 110. The outlet 110 can be used to transfer the polymer dissolving container composition into a solid / liquid separation container 111. For example, the outlet 110 can be used to transfer the polymer dissolving container composition into a filter container 112. That is, as... Figure 1As shown, the solid / liquid separation container 111 may include a filter container 112 and an adsorption separation container 118. In such embodiments, the solid / liquid separation container composition may include the corresponding composition associated with the filter container 112 and the adsorption separation container 118 (at the corresponding time). However, in some embodiments, the solid / liquid separation container 111 may include either the filter container 112 or the adsorption separation container 118. In other words, in some embodiments, the filter container 112 or the adsorption separation container 118 may be absent. In such cases, the outlet of the existing container (filter container 112 or adsorption separation container) (e.g., outlet 116 or outlet 122) is similar to the outlet of the solid / liquid separation container 111.

[0037] Filter container 112 can be made of various materials and has different shapes and / or sizes for various applications. Filter container 112 may include various filter media, such as cloth, wool, linen, fiberglass, steel mesh, sintered metal, and combinations thereof. Filter container 112 may include several known components. Filter container 112 may include rotary drum centrifuges, self-cleaning filters, drum filters, candle filters, leaf filters, and / or rotary pressure filters, etc.

[0038] One or more embodiments specify that the filter container 112 includes a plurality of filters arranged in sequence (e.g., such that a second filter is located downstream of a first filter). That is, the plurality of filters can be configured to continuously filter the filter container composition (or solid / liquid separation composition). The plurality of filters can be configured to remove a first insoluble contaminant. For example, the plurality of filters may include a first filter and a second filter located downstream of the first filter. In such cases, the first filter may have a first size rating, and the second filter may have a second size rating different from (e.g., smaller than) the first size rating. Furthermore, in some embodiments, the first filter may be maintained at a temperature or temperature range different from (e.g., lower than) the temperature or temperature range associated with the second filter. Employing a plurality of filters with different (e.g., successively smaller) size ratings and / or different (e.g., successively larger) temperatures can facilitate aspects thereof, such as the efficient and effective removal of the first insoluble contaminant.

[0039] One or more embodiments specify that filter container 112 can provide solid-liquid separation. For example, one or more insoluble solids (undissolved solids), such as undissolved contaminants, from the polymer dissolution container composition transferred to filter container 112 can be separated from the liquid and soluble (e.g., dissolved) components of the polymer dissolution container composition to prepare a filter container composition. Insoluble contaminants (e.g., separated undissolved solids) can be removed via outlet 114, which may include some unintentional solvent removal. Removal of undissolved contaminants can prepare the filter container composition. Soluble (dissolved) regenerated polymers, such as the filter container composition, can be in a liquid phase, such as a solution or molten state.

[0040] For various applications, the polymer dissolution container composition transferred to the filter container 112 may have different residence times. For example, the polymer dissolution container composition transferred to the filter container may have an average residence time of 0.01 hours to 12 hours within the filter container. This includes all individual values ​​and sub-ranges from 0.01 to 12; for example, the polymer dissolution container composition transferred to the filter container may have an average residence time of a lower limit of 0.01 hours, 0.05 hours, or 0.1 hours to a higher limit of 12 hours, 9 hours, or 6 hours within the filter container.

[0041] The filter container 112 can have a temperature from 70°C to 200°C, such as an operating temperature. This includes all individual values ​​and sub-ranges from 70°C to 200°C; for example, the filter container can have a lower limit of 70°C, 80°C, 90°C, 100°C, or 110°C to an upper limit of 200°C, 190°C, 180°C, or 160°C. One or more embodiments specify that the filter container can have a temperature from 120°C to 200°C, for example when the recycled polymer includes polyethylene.

[0042] The filter container 112 may have a pressure of 20 bar to 235 bar, such as the operating pressure. This includes all individual values ​​and sub-ranges from 20 bar to 235 bar; for example, the filter container may have a lower limit of 20 bar, 30 bar, 40 bar or 60 bar to an upper limit of 235 bar, 225 bar, 215 bar, 200 bar or 190 bar.

[0043] One or more embodiments specify that the polymer dissolving container 104 and the filter container 112 each have a temperature difference of 20°C, a temperature difference of 10°C, or a temperature difference of 5°C.

[0044] One or more embodiments specify that the polymer dissolving container 104 and the filter container 112 each have a pressure difference of less than 30 bar, less than 20 bar, less than 10 bar, less than 5 bar, less than 3 bar, or less than 1 bar.

[0045] The filter container 112 may include an outlet 116. The outlet 116 may be used to transfer the filter container composition into the adsorption separation container 118. The adsorption separation container may be made of various materials and have different shapes and / or sizes for various applications. The adsorption separation container 118 may include many known components. The adsorption separation container 118 may be an intermittent, continuously moving, continuously fixed bed, continuously fluidized bed, or pulsed bed container.

[0046] The adsorption separation container 118 may include a solid medium that can be used to remove contaminants from a filter container composition transferred into the adsorption separation container 118. For example, the solid medium can be used to remove contaminants, such as first soluble contaminants, by adsorption, absorption, electrostatics, size exclusion, ion exclusion, ion exchange, and / or other mechanisms readily apparent to those skilled in the art. For example, pigments and many other contaminants present in regenerated polymers may be polar compounds or may have polar compounds on their surfaces and may preferentially interact with the solid medium, which may also be at least slightly polar. These polar-polar interactions can be particularly advantageous when nonpolar solvents such as alkanes are used as solvents.

[0047] The solid medium can be inorganic materials, carbon-based materials, and combinations thereof. Examples of solid media include zeolites, activated carbon, silica gel, diatomaceous earth, perlite, clay, sand, molecular sieves, glass fibers, and cellulose materials. One or more embodiments specify that the solid medium is selected from zeolites, activated carbon, activated alumina, diatomaceous earth, and combinations thereof. The solid medium can be held within the adsorption separation vessel 118 by a known component (e.g., a solid medium container). The solid medium can be a fluidized bed, stirred, moved as a whole, or held in a fixed position within the adsorption separation vessel 118.

[0048] For various applications, the filter container composition transferred to the adsorption separation vessel 118 may be in contact with the solid medium within the adsorption separation vessel for different durations, such as different residence times. For example, the filter container composition transferred to the adsorption separation vessel 118 may have an average residence time of 0.01 hours to 12 hours within the adsorption separation vessel. This includes all individual values ​​and sub-ranges from 0.01 hours to 12 hours; for example, the filter container composition transferred to the adsorption separation vessel may have an average residence time ranging from a lower limit of 0.01 hours, 0.05 hours, or 0.1 hours to an upper limit of 12 hours, 9 hours, or 6 hours within the adsorption separation vessel.

[0049] The adsorption separation vessel 118 can have a temperature from 70°C to 200°C, such as an operating temperature. This includes all individual values ​​and sub-ranges from 70°C to 200°C; for example, the adsorption separation vessel can have a lower limit of 70°C, 90°C, or 110°C to an upper limit of 200°C, 190°C, 180°C, or 160°C. One or more embodiments specify that the adsorption separation vessel can have a temperature from 120°C to 200°C, for example when the recycled polymer includes polyethylene.

[0050] The adsorption separation vessel 118 may have a pressure of 20 bar to 235 bar, such as the operating pressure. This includes all individual values ​​and sub-ranges from 20 bar to 235 bar; for example, the adsorption separation vessel may have a lower limit of 20 bar, 30 bar, 40 bar or 60 bar to an upper limit of 235 bar, 225 bar, 215 bar, 200 bar or 190 bar.

[0051] An adsorption separation container composition can be provided to remove a first soluble contaminant, such as dissolved contaminants and / or undissolved contaminants, using a solid medium. Because the first soluble contaminant is removed using an adsorption separation container 118 (and a solid medium), the adsorption separation container composition results in less contamination compared to a filter container composition.

[0052] One or more embodiments specify that the adsorption separation vessel can be combined with a filtration vessel, for example, with a solid medium used as a filter aid. For example, the filter aid can be stirred and continuously regenerated. One or more embodiments specify that the adsorption separation vessel can be omitted, for example, the filtration vessel composition can be transferred to an extraction vessel.

[0053] After the filter container composition transferred to the adsorption separation vessel has contacted the solid medium to prepare the adsorption separation vessel composition, for example, when the solid medium approaches its capacity to remove contaminants, the solid medium can be regenerated. Embodiments specify that the solid medium can be regenerated in situ or can be removed from the adsorption separation vessel 118, for example, through outlet 120, for regeneration. Known regeneration components and processes can be used.

[0054] After or simultaneously with the contact of the filter container composition into the adsorption separation container to prepare the adsorption separation container composition, the adsorption separation container composition can be transferred to the extraction container 124 via the outlet 122. The dissolved regenerated polymer, such as the adsorption separation container composition, can be in a liquid phase, such as a solution or a molten state. The extraction container can be made of various materials and has different shapes and / or sizes for various applications.

[0055] Extraction vessel 124 may include several known components. Extraction vessel 124 may be a separator, decanter, and / or extraction column. For example, a rotary or stirred extraction device or extraction column may be used. Examples of suitable extraction vessels include stirred extraction columns and static extraction columns.

[0056] One or more embodiments specify that the extraction vessel 124 utilizes certain conditions, such as temperature and pressure, to enable liquid-liquid extraction. In other words, the conditions of the extraction vessel 124 are such that the adsorption separation vessel composition transferred into the extraction vessel 124 and the extraction vessel composition prepared by removing the first target portion of the solvent and the second soluble contaminant remain in the liquid phase.

[0057] One or more embodiments specify that the extraction vessel 124 utilizes certain conditions, such as temperature and pressure, to enable supercritical extraction. As mentioned, for many embodiments, the extraction vessel composition prepared by removing a first target portion of the solvent and a second soluble contaminant can be maintained in a supercritical phase. Supercritical fluids are above their critical temperature and pressure, for example, above the fluid's critical point. In this supercritical region, supercritical fluids can enhance the removal of contaminants, such as second soluble contaminants, for example, those with relatively high boiling points compared to other contaminants. The operating pressure and temperature can depend on the choice of solvent and solvent concentration, for example, the amount of solvent used with a specific amount of regenerated polymer. Supercritical separation can be carried out in the presence of a solvent-rich and polymer-rich liquid phase. The partitioning of contaminants in the two phases can also be sensitive to the pressure and temperature used.

[0058] For various applications, the adsorption-separation vessel composition transferred to the extraction vessel can have different residence times. For example, the adsorption-separation vessel composition transferred to the extraction vessel can have an average residence time of 0.01 hours to 3 hours within the extraction vessel. This includes all individual values ​​and sub-ranges from 0.01 hours to 3 hours; for example, the adsorption-separation vessel composition transferred to the extraction vessel can have an average residence time of a lower limit of 0.01 hours, 0.05 hours, or 0.1 hours to an upper limit of 3 hours, 2 hours, or 1.5 hours within the extraction vessel.

[0059] One or more embodiments specify that a portion of the extraction vessel composition can be removed from the extraction vessel 124 through outlet 126. The portion of the extraction vessel composition removed through outlet 126 may include a first target portion of the solvent and a second soluble contaminant. One or more embodiments specify that adsorption separation may be performed after the extraction vessel.

[0060] The portion of the extraction container composition removed from the extraction container 124 through the outlet 126 may be 15% to 90% by weight of the material transferred into the extraction container (e.g., the adsorption separation container composition transferred into the extraction container). This includes all individual values ​​and sub-ranges from 15% to 90% by weight; for example, the portion of the extraction container composition removed from the extraction container through the outlet 126 may be from a lower limit of 15%, 20%, or 25% by weight to an upper limit of 90%, 85%, or 80% by weight.

[0061] Similarly, the first target portion of the solvent removed from the extraction vessel 124 through the outlet 126 may be 15% to 95% by weight of the solvent (e.g., the solvent transferred to the polymer dissolution vessel 104 and other solvents input into the system 102). This includes all individual values ​​and sub-ranges from 15% to 95% by weight; for example, based on the total weight of the solvent transferred to the polymer dissolution vessel 104, the first target portion of the solvent removed from the extraction vessel through the outlet 126 may be a lower limit of 15%, 20%, or 25% by weight to an upper limit of 95%, 90%, or 85% by weight.

[0062] As mentioned, the second soluble contaminant can be removed from the extraction vessel 124 through the outlet 126. The second soluble contaminant includes non-volatile contaminants. Examples of second soluble contaminants include organoleptics, antioxidants, plasticizers, anti-caking agents, antistatic agents, adhesives, ink components, and combinations thereof. For different applications, various amounts of the second soluble contaminant can be removed from the extraction vessel through the outlet 126.

[0063] The extraction vessel 124 can have a temperature from 160°C to 300°C, such as the operating temperature. This includes all individual values ​​and sub-ranges from 160°C to 300°C; for example, the extraction vessel can have a lower limit of 160°C, 170°C, 180°C, or 190°C to an upper limit of 300°C, 280°C, 270°C, or 260°C.

[0064] Extraction vessel 124 may have a pressure from 30 bar to 300 bar, such as the operating pressure. This includes all individual values ​​and sub-ranges from 30 bar to 300 bar; for example, the extraction vessel may have a lower limit of 30 bar, 50 bar, 70 bar, 80 bar, 100 bar or 120 bar to an upper limit of 300 bar, 250 bar, 200 bar or 180 bar.

[0065] After or simultaneously with the removal of the first target portion of the solvent and the second soluble contaminant from the extraction vessel 124 through the outlet 122, the remainder of the extraction vessel composition can be transferred to the polymer concentration vessel 130. The polymer concentration vessel can be made of various materials and has different shapes and / or sizes for various applications. The polymer concentration vessel 130 may include many known components, such as a throttle valve, heater, separator, devolatilizer, or gas purger. Although a single polymer concentration vessel 130 is illustrated, embodiments are not limited thereto. For example, the polymer concentration vessel 130 may include one or more flash vessels. For example, the polymer concentration vessel 130 may include a series (e.g., three) of flash vessels, such as flash separators / flash tanks.

[0066] The remainder of the extraction vessel composition transferred to the polymer concentration vessel 130 (which may be, for example, in the fluid phase) may undergo a pressure reduction, for example, by passing through one or more throttling valves or other throttling devices. One or more embodiments specify that the polymer concentration vessel 130 may utilize a series of pressure reductions (e.g., where a particular pressure reduction is lower than a previous pressure reduction) to remove a second target fraction and a third soluble contaminant of the solvent to prepare a purified regenerated polymer. The second target fraction and the third soluble contaminant of the solvent may be removed from the polymer concentration vessel 130 through outlet 132.

[0067] The second target portion of the solvent removed from the polymer concentration container 130 through outlet 132 may be 5% to 85% by weight of the solvent (e.g., the solvent transferred to the polymer dissolution container 104). This includes all individual values ​​and sub-ranges from 5% to 85% by weight; for example, based on the total weight of the solvent transferred to the polymer dissolution container 104, the second target portion of the solvent removed from the polymer concentration container 130 through outlet 132 may be a lower limit of 5%, 10%, or 15% by weight to an upper limit of 85%, 80%, or 75% by weight.

[0068] One or more embodiments specify that 75% to 99.9999% by weight of all solvents fed into system 102 can be separated from the purified regenerated polymer. This includes all individual values ​​and sub-ranges from 75% to 99.9999% by weight; for example, the percentage by weight of all solvents fed into the system that can be separated from the purified regenerated polymer can be a lower limit of 75%, 85%, or 95% by weight to an upper limit of 99.9999% by weight.

[0069] Examples of third soluble contaminants include sensory agents, antioxidants, plasticizers, anti-caking agents, antistatic agents, ink components, and combinations thereof, which are not removed from the extraction vessel 124 through the outlet 126. One or more embodiments specify that the third soluble contaminant has a boiling point lower than that of the first and second soluble contaminants.

[0070] The polymer concentration vessel 130 can have a temperature range of 130°C to 300°C, such as the operating temperature. This includes all individual values ​​and sub-ranges from 130°C to 300°C; for example, the polymer concentration vessel can have a lower limit of 130°C, 150°C, or 170°C to an upper limit of 300°C, 270°C, or 240°C.

[0071] The polymer concentration vessel 130 may have a pressure from 0.02 bar (e.g., vacuum) to 50 bar, such as the operating pressure. This includes all individual values ​​and sub-ranges from 0.02 bar to 50 bar; for example, the polymer concentration vessel may have a lower limit of 0.02 bar, 0.03 bar, or 0.04 bar to an upper limit of 50 bar, 40 bar, or 30 bar.

[0072] The purified regenerated polymer can be removed from the polymer concentration vessel 130 through outlet 134. After removal from the polymer concentration vessel 130, the purified regenerated polymer can undergo a number of further processing steps, such as granulation.

[0073] Purified regenerated polymers can possess a variety of properties desired for various applications. For example, purified regenerated polymers can provide low residual solvent, low odor, low gelation, desired color and / or good mechanical properties, while exhibiting a reduction in controlled contamination (e.g., the various contaminants discussed earlier).

[0074] One or more embodiments specify that the solid media, as previously discussed, can be used with, for example, added to, the filter container 112. For example, the solid media, as previously discussed, can be used as a filter aid for a variety of applications. When the solid media is used with the filter container 112, one or more embodiments specify that the filter container composition prepared using the solid media is transferred to the extraction container 124. In other words, one or more embodiments specify that the filter container composition prepared using the solid media is transferred to the extraction container 124. Figure 1The filter container 112 and the adsorption separation container 118 shown are combined in such a way that the adsorption separation container 118 can be omitted.

[0075] In embodiments where solid media are used with a filter container, as previously discussed, a second undissolved contaminant is removed to prepare a filter container composition, for example, rather than to prepare an adsorption separation container composition. As mentioned, the filter container composition can then be transferred to an extraction container.

[0076] In embodiments where solid media are used in conjunction with a filter container, the polymer dissolving container and the filter container may each have a temperature difference of up to 20°C, up to 10°C, or up to 5°C.

[0077] In embodiments where solid media are used in conjunction with a filter container, the polymer dissolving container and the filter container may have pressures that differ from each other by no more than 10 bar, no more than 5 bar, no more than 3 bar, or no more than 1 bar.

[0078] In one or more embodiments, the solvent can be purified in a separate process step and recycled back into the dissolution and / or extraction vessel, thus reducing the amount of fresh solvent required for the method.

[0079] Figure 2 Examples of a portion of system 260 according to one or more embodiments of the present disclosure are illustrated. For example, system 260 can be used when more than one regenerated polymer needs to be purified.

[0080] System 260 may include and / or utilize references Figure 1 The components discussed are similar to several other components. For example, system 260 may include: polymer dissolving containers 204A, 204B, including inlet ports 206A, 206B, inlet ports 208A, 208B and outlet ports 210A, 210B; filter containers 212A, 212B, including outlet ports 214A, 214B and outlet ports 216A, 216B; adsorption separation containers 218A, 218B, including outlet ports 220A, 220B and outlet ports 222A, 222B; extraction containers 224A, 224B, including 226A, 226B and outlet ports 228A, 228B; and polymer concentration containers 230A, 230B, including outlet ports 232A, 232B and outlet ports 234A, 234B.

[0081] like Figure 2 As shown, system 260 may include two parallel systems 102, such as Figure 1As shown, the outlet of the filter container 212A can be used as the inlet of the dissolving container 204B. For example, a first regenerated polymer (such as polyethylene) can be selectively dissolved in the dissolving container 204A and purified by the filtration (e.g., using the filter container 212A), adsorption separation (e.g., using the adsorption separation container 218A), and extraction (e.g., using the extraction container 224A) steps in a first example of the disclosed method, including the removal of insoluble impurities of a second regenerated polymer (undissolved polymer from the dissolving container 204A) (such as polypropylene) as solids from the filter container 212A. This solid stream including the second regenerated polymer can then be used as a feedstock for a second example of the disclosed method, wherein, for example, polypropylene is selectively dissolved in the second dissolving container 204B at different temperatures, pressures, and / or solvents using the dissolving container 204B, undissolved impurities are removed in the second filter container 212B, and then purified from the dissolved impurities in a second adsorption separation (e.g., using the adsorption separation container 218B) and extraction (e.g., using the extraction container 224B). In principle, this parallel application of multiple instances of the disclosed method can be used to purify a variety of different polymers present in the same recycled polymer feedstock.

[0082] Several aspects of this disclosure are provided below.

[0083] Aspect 1 provides a method for purifying a regenerated polymer, the method comprising: transferring the regenerated polymer to a polymer dissolving container, wherein the regenerated polymer comprises a solid; selectively dissolving the solid regenerated polymer in the polymer dissolving container with a solvent to prepare a polymer dissolving container composition, wherein the polymer dissolving container has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar; transferring the polymer dissolving container composition to a solid / liquid separation container to remove a first insoluble contaminant and prepare a solid / liquid separation container composition, wherein the solid / liquid separation container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar, wherein the solid / liquid separation container includes one or more filtration containers, adsorption separation containers, or combinations thereof; transferring the solid / liquid separation container composition to an extraction container to remove a first target fraction and a second soluble contaminant of the solvent to prepare an extraction container composition, wherein the extraction container has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar; and transferring the extraction container composition to a polymer concentration container to remove a second target fraction and a third soluble contaminant of the solvent to prepare a purified regenerated polymer.

[0084] Aspect 2 provides the method according to aspect 1, wherein the recycled polymer is selected from polyethylene and polypropylene.

[0085] Aspect 3 provides a method according to aspect 1 and / or aspect 2, wherein the solvent comprises an alkane.

[0086] Aspect 4 provides the method according to Aspect 1, Aspect 2 and / or Aspect 3, wherein the alkane solvent is selected from C5-C7 alkanes with a boiling point of 25°C to 90°C.

[0087] Aspect 5 provides a method according to Aspect 1, Aspect 2, Aspect 3 and / or Aspect 4, wherein the solid / liquid separation vessel includes a filtration vessel and an adsorption separation vessel.

[0088] Aspect 6 provides a method according to Aspect 1, Aspect 2, Aspect 3, Aspect 4 and / or Aspect 5, wherein the solid / liquid separation container includes a filter container, wherein the filter container includes a plurality of filters to remove the first insoluble contaminant, wherein the plurality of filters includes a first filter and a second filter located downstream of the first filter, wherein the first filter has a first size rating and the second filter has a second size rating smaller than the first size rating, and wherein the first filter is maintained at a temperature lower than that of the second filter.

[0089] Aspect 7 provides the method according to Aspect 1, Aspect 2, Aspect 3, Aspect 4, Aspect 5 and / or Aspect 6, wherein the polymer dissolving container has a temperature of 110°C to 160°C and a pressure of greater than 30 bar to 100 bar.

[0090] Aspect 8 provides a method according to Aspect 1, Aspect 2, Aspect 3, Aspect 4, Aspect 5, Aspect 6 and / or Aspect 7, wherein the polymer dissolving container is configured at a certain temperature and pressure to maintain the polymer dissolving container composition above the cloud point of the polymer dissolving container composition.

[0091] Aspect 9 provides the method according to Aspect 1, Aspect 2, Aspect 3, Aspect 4, Aspect 5, Aspect 6, Aspect 7 and / or Aspect 8, wherein the method is based on the total weight of the solid regenerated polymer and the solvent transferred to the polymer dissolution container to prepare the polymer dissolution container composition, wherein the solvent is 70% to 95% by weight.

[0092] Aspect 10 provides a method for purifying a regenerated polymer, the method comprising: transferring a solid regenerated polymer to a polymer dissolving container; selectively dissolving the solid regenerated polymer in the polymer dissolving container with a solvent to prepare a polymer dissolving container composition, wherein the polymer dissolving container has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar, such that the polymer dissolving container is configured to operate above the cloud point of the polymer dissolving container composition; transferring the polymer dissolving container composition to a filtration container to remove a first insoluble contaminant and a first soluble contaminant and to prepare a filtration container composition, wherein the filtration container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar; transferring the filtration container composition to an extraction container to remove a first target fraction and a second soluble contaminant of the solvent to prepare an extraction container composition, wherein the extraction container has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar; and transferring the extraction container composition to a polymer concentration container to remove a second target fraction and a third soluble contaminant of the solvent to prepare a purified regenerated polymer.

[0093] Example

[0094] Example 1 was performed as follows. Calculations for the method of purifying the regenerated polymer were performed using an Aspen Plus V10 (available from Aspen Technology). For the calculations, the polymers (polyethylene and polypropylene), solvent (n-pentane), and contaminants (calcium carbonate (2% by weight in the polymer), limonene (100 ppm), butylated hydroxytoluene (100 ppm), 1-decaldehyde (100 ppm), dibutyl phthalate (100 ppm), and bisphenol A (100 ppm)) were used.

[0095] For calculations, the PC-SAFT (perturbed chainstatistical associating fluid theory) equation of state model was used. Many univariate parameters are available in the Aspen Plus database (e.g., for polyethylene, polypropylene, and many solvents). For univariate parameters not available in the Aspen Plus database, regressions were performed on liquid density, liquid heat capacity, and liquid vapor pressure data available from the TDE NIST database (Thermo Data Engine, National Institute of Standards and Technology). Publicly available mixture data were used to adjust the binary interaction parameters.

[0096] For the calculations, recycled polyethylene (e.g., corresponding to inlet 106 as discussed herein and referred to as Calculation Stream (CS) 106) is fed together with pentane (e.g., corresponding to inlet 108 as discussed herein and referred to as CS 108) into a dissolving vessel (e.g., as discussed herein); at 80 bar and 110 °C, polyethylene selectively dissolves in pentane compared to polypropylene. The effluent from the dissolving vessel undergoes subsequent solid / liquid separation (e.g., as discussed herein) to remove undissolved polypropylene and calcium carbonate, resulting in CS 122 (e.g., corresponding to outlet 122 as discussed herein). Calculations show that insoluble components, such as polypropylene (e.g., 100% removal) and calcium carbonate (e.g., 100% removal), are removed. CS 122 is further pressurized (to 100 bar) and heated (to 225 °C) before being fed into a one-stage extraction vessel (e.g., as discussed herein); in this step, non-volatile contaminants are removed better than by devolatilization alone. From the extraction, the solvent-rich light phase is cleaned and recycled, and the polymer-rich heavy phase is subjected to further devolatilization (e.g., in a polymer concentration vessel as discussed herein). From the devolatilization, solvent vapors are collected, contaminants are removed, and the clean solvent is recycled. The final devolatilization step is carried out at 20 bar and 250°C. Then, for CS 134 (e.g., corresponding to outlet 134 as discussed herein), it has been shown that approximately 99 wt% of limonene and decanal, approximately 90 wt% of butylated hydroxytoluene and dibutyl phthalate, and approximately 50 wt% of bisphenol A are removed. Several calculated feed conditions and compositions are shown in Table 1.

[0097]

[0098] The data in Table 1 indicate that the regenerated polymer is purified. The data in Table 1 also demonstrate the improved contaminant removal efficiency compared to other polymer purification processes. For Example 1, a solid polymer was used, and compared to other polymer purification processes, Example 1 provides a purified regenerated polymer with improved, for example, lower amounts of residual solvent and / or lower (absent) amounts of residual polypropylene.

Claims

1. A method for purifying regenerated polymers, the method comprising: The regenerated polymer is transferred to a polymer dissolution container, wherein the regenerated polymer comprises a solid. The solid regenerated polymer is selectively dissolved in a solvent in the polymer dissolving container to prepare a polymer dissolving container composition, wherein the polymer dissolving container has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar. The polymer dissolving container composition is transferred to a solid / liquid separation container to remove a first insoluble contaminant and to prepare a solid / liquid separation container composition, wherein the solid / liquid separation container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar, wherein the solid / liquid separation container includes one or more filter containers, adsorption separation containers or combinations thereof; The solid / liquid separation container composition is transferred into an extraction container to remove a first target portion and a second soluble contaminant of the solvent to prepare the extraction container composition, wherein the extraction container has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar. as well as The extraction vessel composition is transferred to a polymer concentration vessel to remove a second target fraction of the solvent and a third soluble contaminant, in order to prepare a purified regenerated polymer.

2. The method according to claim 1, wherein the recycled polymer is selected from polyethylene and polypropylene.

3. The method of claim 1, wherein the solvent comprises an alkane.

4. The method according to claim 3, wherein the alkane solvent is selected from C5-C7 alkanes with a boiling point of 25°C to 90°C.

5. The method according to claim 1, wherein the solid / liquid separation container comprises a filtration container and an adsorption separation container.

6. The method of claim 1, wherein the solid / liquid separation container comprises a filter container, wherein the filter container comprises a plurality of filters to remove the first insoluble contaminant, wherein the plurality of filters comprises a first filter and a second filter located downstream of the first filter, wherein the first filter has a first size rating and the second filter has a second size rating smaller than the first size rating, and wherein the first filter is maintained at a temperature lower than that of the second filter.

7. The method of claim 1, wherein the polymer dissolving container has a temperature of 110°C to 180°C and a pressure of greater than 30 bar to 120 bar.

8. The method of claim 1, wherein the polymer dissolving container is configured at a certain temperature and pressure to maintain the polymer dissolving container composition above the cloud point of the polymer dissolving container composition.

9. The method of claim 1, wherein the solvent is 70% to 95% by weight, based on the total weight of the solid regenerated polymer and the solvent transferred to the polymer dissolving container to prepare the polymer dissolving container composition.

10. A method for purifying regenerated polymers, the method comprising: Transfer the solid recycled polymer to a polymer dissolution container; The solid regenerated polymer is selectively dissolved in a solvent in the polymer dissolving container to prepare a polymer dissolving container composition, wherein the polymer dissolving container has a temperature of 70°C to 180°C and a pressure of 20 bar to 120 bar, such that the polymer dissolving container is configured to operate above the cloud point of the polymer dissolving container composition. The polymer dissolving container composition is transferred into a filter container to remove a first insoluble contaminant and a first soluble contaminant and to prepare a filter container composition, wherein the filter container has a temperature of 70°C to 200°C and a pressure of 20 bar to 235 bar. The filter container composition is transferred into an extraction container to remove a first target portion and a second soluble contaminant of the solvent to prepare an extraction container composition, wherein the extraction container has a temperature of 160°C to 300°C and a pressure of 30 bar to 300 bar. as well as The extraction vessel composition is transferred to a polymer concentration vessel to remove a second target fraction of the solvent and a third soluble contaminant, in order to prepare a purified regenerated polymer.

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