Method for purifying regenerated polymer

Abstract

A process for purifying a regenerated polymer to a purer polymer is disclosed. In an embodiment of the invention, a method involves obtaining a regenerated polymer; leaching the various contaminants with a leaching solvent to produce a leached polymer; and then dissolving the leached polymer in a solvent to produce a first solution comprising the dissolved polymer. The first solution is settled and then filtered. A purer polymer is separated from the resulting solution.

Description

Technical Field

[0001] The present invention generally relates to a method for purifying contaminated recycled polymer into a purer polymer by combining an immersion leaching step with a purification step using a leaching solvent and a pressurized solvent. More specifically, the recycled polymer is selected from post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof. The purer polymer is colorless or transparent, odorless, and virgin. The present invention is particularly suitable for purifying polyolefins, such as polyethylene and polypropylene. Background Art

[0002] Synthetic polymers are ubiquitous in everyday life due to their relatively low production costs and well-balanced material properties. They are used in a wide range of applications, such as packaging, automotive components, medical devices, and consumer goods. To meet the high demands of these applications, hundreds of millions of tons of synthetic polymers are produced globally each year. The vast majority of these polymers are produced from increasingly scarce fossil sources, such as petroleum and natural gas. Furthermore, the production of these synthetic polymers from fossil sources results in the emission of greenhouse gases (GHGs), primarily CO2, into the atmosphere.

[0003] The widespread use of synthetic polymers has resulted in the generation of millions of tons of plastic waste each year. While most plastic waste is landfilled through municipal solid waste programs, a significant portion is found in the environment as litter, which is unsightly and potentially harmful to ecosystems. Plastic waste is often washed into river systems and ultimately out to sea.

[0004] Plastic recycling has emerged as a solution to alleviate the problems associated with widespread plastic use. Recycling and reusing plastics diverts waste from landfills and reduces the demand for virgin plastics made from fossil-based resources, thereby reducing greenhouse gas emissions. In developed regions, such as the United States and the European Union, plastic recycling rates are increasing due to increased awareness among consumers, businesses, and industrial manufacturing. Most recycled materials, including plastics, are mixed into a single stream that is collected and processed by material recycling facilities (MRFs). At MRFs, the materials are sorted, washed, and packaged for resale. Plastics can be separated into individual materials, such as high-density polyethylene (HDPE) or polyethylene terephthalate (PET), or mixed streams of other common plastics, such as polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), poly(vinyl chloride) (PVC), polystyrene (PS), polycarbonate (PC), and polyamide (PA). The single or mixed streams can then be further sorted, washed and reprocessed in a plastics recycling facility (PRF) into pellets suitable for reuse in plastics processing such as blow molding, profile extrusion, injection molding and film making.

[0005] Although recycled plastics are sorted into primarily homogeneous streams and washed with aqueous and / or caustic solutions, the final reprocessed pellets are often still highly contaminated with unwanted waste impurities, such as spoiled food scraps and residual flavor components. Furthermore, due to the mixture of dyes and pigments commonly used to color plastic products, recycled plastic pellets, with the exception of those from recycled beverage containers, are all dark in color. While there are some applications that are less sensitive to color and contamination (e.g., black plastic paint containers and concealed automotive parts), most applications require colorless pellets. The demand for high-quality, "virgin" recycled resins is particularly important for food and pharmaceutical contact applications, such as food packaging. In addition to being contaminated by impurities and mixed colorants, many recycled resin products are often heterogeneous in chemical composition and may contain significant amounts of polymer contaminants, such as polyethylene (PE) contamination in recycled PP, and PP contamination in recycled polyethylene (PE).

[0006] The use of these recycled plastics is currently limited due to contamination, which makes the plastics less valuable than virgin plastics. The key to increasing recycling rates and reducing GHG emissions and plastic pollution is to reduce contamination to a level that allows for wider use in more end markets, especially those involving demanding applications.

[0007] Film is a special case of recycled plastics and is primarily polyolefin in composition. Film presents unique challenges for recycling that have yet to be addressed. The recycled film supply stream can be divided into two general categories: 1) pre-consumer recycled film, which includes in-plant scrap / offcuts that can be reused in the same process that produces the film, and PIR film, which is film produced from in-plant scrap that is not used in the same process that produces it; and 2) PCR film, which includes post-commercial recycled film and post-home recycled film. The post-commercial recycled film is film that has been used in commerce but not directly by home consumers (e.g., post-store shrink wrap, pallet packaging, wholesale bags, furniture packaging, agricultural film, etc.), and the post-home recycled film is film that has been used directly by home consumers in commerce (e.g., retail bags, retail food packaging, outer packaging for diapers and sanitary products, garbage bags, etc.). PIR film waste for recycling is collected on a plant-by-plant basis in controlled end markets and may or may not involve (or require) significant cleaning steps before recycling. PCR membranes are collected at the point of sale and shipped to various PRFs dedicated to membranes for use in various cleaning operations and ultimate distribution to end markets. In the United States, post-consumer membranes are primarily collected in store take-back programs where the end consumer returns the membrane to a collection bin at a local store. Membrane-based PRFs collect membrane waste and ship it to end markets after sorting and cleaning. The use of membrane recycling materials is very limited due to contamination. Contamination of membranes is higher than other forms due to their high surface area to volume ratio, which creates a greater chance of external contamination. Currently, most membrane-based recycled plastics are down-cycled into non-circular and limited size markets such as plastic lumber. As membrane-based waste collection grows, demand for end markets other than plastic lumber is essential. Ideally, membrane-based waste will eventually find reuse in membrane-based applications, ensuring a continuous cycle.

[0008] End-use markets cannot grow unless contamination is significantly reduced. Given the large volumes of membranes used in demanding applications, it is crucial that recycled plastics from these markets re-enter the same end-use markets to support circularity. Therefore, the ability to remove even higher levels of contaminants is crucial to achieving circularity and reducing GHG emissions and plastic pollution. Plastic contamination is even more problematic for membranes given the significant surface area per use and the mobility of waste materials in the environment via air and water.

[0009] While contamination is problematic for all end-market applications, demanding applications have even more stringent requirements, especially for certain chemical contaminants. Relevant chemical contaminants are categorized into various chemical classes based on their chemical structure. Non-limiting examples of these chemical classes of contaminants are heavy metals, pesticides, dioxins, furans, polychlorinated biphenyls (PCBs), phthalates, polycyclic aromatic hydrocarbons (PAHs), organotins, bisphenols, isothiazolinones, glyphosate, alkylphenols, alkylphenol ethoxylates, aromatic amines, and flame retardants. Furthermore, target levels for these contaminants can be extremely low. For example, target levels can be on the order of parts per million (ppm), parts per billion (ppb), and parts per trillion (ppt), where the initially contaminated plastic may contain levels 1,000 times higher than the target level. Thus, a 1,000-fold reduction in chemical contamination is often required.

[0010] Mechanical recycling, also known as secondary recycling, is the process of converting recycled plastic waste into a reusable form for subsequent manufacturing. A more detailed review of mechanical recycling and other plastic recycling methods is described in SM Al-Salem, P. et al., Waste Management , 29(10) (2009), 2625-2643. Mechanical recycling of rigid plastics typically involves some form of surface washing followed by drying and melt densification. The melt densification step typically includes melt filtration and devolatilization. Although advances in mechanical recycling technology have improved the quality of recycled polymers to some extent, there are still fundamental limitations to mechanical purification methods, such as physical entrapment of pigments within the polymer matrix. Therefore, even with improvements in mechanical recycling technology, the dark color and high levels of chemical contamination in currently available recycled plastic waste have hindered the widespread use of recycled resins by the plastics industry. For film-based materials, there are dry and wet processes. In the dry process, a controlled film stream is typically chopped, dried, and then melt-extruded into the final form. Melt filtration and devolatilization are typically part of the extrusion step. In the wet process, a controlled film stream is typically chopped, washed in one or more aqueous solutions, dried, and then melt-extruded into the final form. Melt filtration and devolatilization are typically part of the extrusion step. The above methods are generally acceptable at removing intentional surface contaminants such as paper labels and unintentional surface contaminants such as dirt, but are poor at removing bulk contaminants.

[0011] U.S. Patent No. 10,022,725 discloses a mechanical recycling method for cleaning linear low-density polyethylene (LLDPE) / LDPE film for recycling. The '725 patent also discloses the steps of shredding, a first water washing step, a second comminution step involving wet grinding, one or more friction washing steps using hot water in at least one step, drying or multiple drying steps, and a compacting step. This method can be quite effective in removing some loosely bound surface contaminants, but will be ineffective in removing bulk contaminants due to the extremely low solubility of bulk contaminants in the aqueous washing medium and / or the limited diffusion rate of bulk contaminants within the plastic.

[0012] U.S. Patent No. 9,616,595 discloses a method for mechanically recycling deinked surface-printed plastic film. The '595 patent also discloses the steps of grinding, ink removal, general washing, cleaning solution recovery, pigment recovery, and drying. The ink removal step involves the use of an aqueous cleaning fluid with a high pH, ​​a selective cleaning agent such as lauryl sulfate, and high turbulence. The method claims the ability to remove surface-printed ink, which can lead to chemical contamination after heating during recycling. However, the method has limited ability to remove bulk contaminants due to the limited solubility of the bulk contaminants in the aqueous washing medium and / or the limited diffusion rate of the bulk contaminants in the plastic.

[0013] To overcome the fundamental limitations of mechanical recycling, numerous methods have been developed to purify contaminated polymers through chemical methods or chemical recycling. Most of these methods use solvents to clean and purify the polymers. The use of solvents enables the extraction of impurities and the dissolution of the polymer, further enabling alternative separation techniques. For example, U.S. Patent No. 7,935,736 describes a method for recycling polyester from polyester-containing waste by using a solvent to dissolve the polyester prior to cleaning. The '736 patent also describes the need to use a precipitant to recover the polyester from the solvent.

[0014] U.S. Patent No. 6,555,588 describes a method for producing polypropylene blends from plastic mixtures containing other polymers. The '588 patent describes extracting contaminants from the polymer at a temperature below the polymer's solubility in a selected solvent, such as hexane, and for a specified residence time. The '588 patent also describes increasing the temperature of the solvent (or a second solvent) to dissolve the polymer prior to filtration. The '588 patent also describes using shear or flow to precipitate the polypropylene from the solution. The polypropylene blends described in the '588 patent contain up to 5.6% polyethylene contaminant by weight.

[0015] European Patent Application No. 849,312 (translated from German into English) describes a method for obtaining purified polyolefins from polyolefin-containing plastic mixtures or polyolefin-containing waste. The '312 patent application describes extracting the polyolefin mixture or waste with the hydrocarbon portion of gasoline or diesel fuel having a boiling point above 90°C at a temperature between 90°C and the boiling point of the hydrocarbon solvent. The '312 patent application also describes contacting the hot polyolefin solution with bleaching clay and / or activated carbon to remove foreign components from the solution. The '312 patent also describes cooling the solution to a temperature below 70°C to crystallize the polyolefin, followed by removing the adhering solvent by heating the polyolefin above its melting point, evaporating the adhering solvent in a vacuum, passing a gas stream through the polyolefin to precipitate it, and / or extracting the solvent with an alcohol or ketone having a boiling point below the melting point of the polyolefin.

[0016] U.S. Patent No. 5,198,471 discloses a method for separating a polymer from a physically mixed solid mixture containing multiple polymers (e.g., waste plastics) using a solvent at a first, lower temperature to form a first, single-phase solution and a remaining solid component. The '471 patent also describes heating the solvent to a higher temperature to dissolve additional polymers that were insoluble at the first, lower temperature. The '471 patent also describes filtering the insoluble polymer component.

[0017] U.S. Patent No. 5,233,021 describes a method for extracting pure polymer components from a multi-component structure (e.g., waste carpet) by dissolving each component in a supercritical fluid at a suitable temperature and pressure, and then varying the temperature and / or pressure to sequentially extract specific components. However, similar to the '471 patent, the '021 patent only describes filtration of the precipitated component.

[0018] U.S. Patent No. 5,739,270 describes a method and apparatus for continuously separating the polymer component of a plastic from contaminants and other components of the plastic using a cosolvent and a working fluid. The cosolvent at least partially dissolves the polymer, and a second fluid (i.e., in a liquid, critical, or supercritical state) solubilizes the components from the polymer and precipitates some of the polymer dissolved in the cosolvent. The '270 patent also describes a step for filtering the thermoplastic cosolvent (with or without the working fluid) to remove particulate contaminants, such as glass particles.

[0019] U.S. Patent No. 5,368,796 discloses a method for surface cleaning polyethylene films. The '796 patent further discloses the following steps: shredding, a first surface wash step (involving a boiling solvent at a temperature below the polyethylene's melting temperature and at or near ambient pressure, with 30 minutes of vigorous mechanical agitation to remove ink), a second surface wash step (involving a fresh solvent below the polyethylene's melting temperature, with 30 minutes of vigorous mechanical agitation), a third surface wash step (involving a solvent below the polyethylene's melting temperature, with 30 to 60 minutes of vigorous mechanical agitation, and devolatilization), and melt densification. Optionally, the method may include a water wash step prior to treatment with a solvent to remove surface contaminants. The '796 patent also discloses that solvent washing achieves extraction, wherein the solvent does not dissolve the polymer. However, a small amount of wax can be removed, typically less than 1% by weight. The solvent wash and extraction steps are further disclosed as being carried out at the boiling point of the solvent, which is selected to be below the softening point of the polyethylene to prevent agglomeration. The above methods focus on the removal of surface printing inks and do not address the removal of bulk permeable contaminants such as those previously described.

[0020] U.S. Patent Application No. 2009 / 0178693 discloses a method for purifying plastics. The '693 patent application further discloses a multi-step process involving pelletization to form plastic flakes, surface washing with supercritical CO2, surface washing and extraction with a high-boiling-point solvent or solvent mixture (such as limonene and ethylene lactate), a final surface washing with supercritical CO2 to remove the high-boiling-point solvent from the surface, and devolatilization. The invention also discloses that the plastic flake feed material is stirred with the solvent and that the flakes are maintained in shape. Furthermore, the invention discloses that the recovered material remains as flakes, meaning that the process is completed at a temperature below the initial melting point of the plastic.

[0021] U.S. Patent No. 9,834,621 discloses a method for purifying polypropylene. The '621 patent further discloses contacting recycled polypropylene with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of about 80°C to about 280°C and a pressure of about 10 atm to about 544 atm to produce extracted recycled polypropylene; dissolving the extracted recycled polypropylene in a solvent selected from the first fluid solvent, a second fluid solvent, and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a first solution comprising polypropylene, at least one dissolved contaminant, and at least one suspended contaminant; and dissolving the extracted recycled polypropylene in a solvent selected from the first fluid solvent, a second fluid solvent, and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a first solution comprising polypropylene, at least one dissolved contaminant, and at least one suspended contaminant. The invention relates to a method for separating the polypropylene from the first fluid solvent by settling a first solution at a temperature of 0°C and a pressure of about 14 atm to about 544 atm to produce a second solution comprising polypropylene, at least one dissolved contaminant, and less of at least one suspended contaminant; filtering the second solution at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a third solution comprising purer polypropylene, at least one dissolved contaminant, and even less of at least one suspended contaminant; and separating the purer polypropylene from the third solution; wherein the second fluid solvent has the same chemical composition as or a different chemical composition than the first fluid solvent. The above-described methods are well-suited for removing contaminants. However, the ability to dissolve, settle, and filter plastics is difficult and may not be feasible or practical for plastics with high molecular weights (MW), such as those used in films and blow-molded containers. Furthermore, the above-described methods do not address the removal of surface contaminants prior to extraction and dissolution, thereby burdening such disclosed methods, particularly filtration.

[0022] In summary, the known solvent-based methods for purifying contaminated plastics, as described above, do not produce "virgin" polymers because they do not address the problem of sufficiently and effectively removing surface and bulk contaminants from the plastic to enable use in demanding applications, particularly film and rigid applications involving high MW plastics. In addition, co-dissolution of other polymers and thus cross-contamination often occurs in previous methods. If an adsorbent is used, filtration and / or centrifugation steps are typically employed to remove the used adsorbent from the solution. Furthermore, separation processes to remove the solvent, such as heating, vacuum evaporation, and / or precipitation using precipitation chemicals, are used to produce polymers free of residual solvent.

[0023] Therefore, there is a need for an improved solvent-based process for purifying contaminated recycled polymers that: 1) uses a solvent that can be easily and economically removed from the polymer; 2) removes surface and bulk contamination in an efficient manner; 3) is readily simple in terms of the number of unit operations; 4) can be used in high MW plastics, such as those derived from films and rigid applications; 5) produces polymers without causing substantial cross-contamination of polymers; and 6) produces virgin polymers (i.e., having properties similar to virgin polymer; essentially free of contaminants, colorless, odorless, etc.). Summary of the Invention

[0024] In an embodiment of the present invention, a method for purifying a recycled polymer is disclosed. The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer contains contaminants, each of which has a concentration; and wherein the recycled polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) leaching the recycled polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm for a total residence time and a residence time in each of the leaching stages. Leaching the alkylphenol, bisphenol, dioxin, PCB or phthalate from the recycled polymer at an average removal efficiency to produce a leached polymer comprising at least one of the alkylphenol, bisphenol, dioxin, PCB or phthalate, each having a concentration; and wherein the average removal efficiency is greater than about 55%; c) dissolving the leached polymer in a solvent selected from a first fluid solvent, a second fluid solvent, and a solvent at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). and mixtures thereof to produce a first solution comprising a dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; d) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant; e) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant; f) filtering the third solution by adsorptive filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising a twice-filtered polymer; and g) separating the twice-filtered polymer from the fourth solution to produce a purer polymer; and wherein the second fluid solvent has the same chemical composition as the first fluid solvent or a different chemical composition.

[0025] In an embodiment of the present invention, a method for purifying a recycled polymer is disclosed.The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a certain concentration; and wherein the recycled polymer contaminants comprise at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a recycled polymer comprising 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. 118 and 2-ethylhexyl phthalate, each of the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate having a certain concentration; wherein the average removal efficiency is greater than about 55%; d) dissolving the leached polymer in a solvent selected from a first fluid solvent, a second fluid solvent and a mixture thereof at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising the dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant; e) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising the settled polymer, at least one dissolved contaminant and less of at least one suspended contaminant; f) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising the settled polymer, at least one dissolved contaminant and less of at least one suspended contaminant; g) filtering the third solution by adsorptive filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtered polymer, at least one dissolved contaminant, and even less of at least one suspended contaminant; g) filtering the third solution by adsorptive filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising a twice-filtered polymer; and h) separating the twice-filtered polymer from the fourth solution to produce a purer polymer; and wherein the second fluid solvent has the same chemical composition as the first fluid solvent or a different chemical composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A It is a flowchart showing the main steps of one embodiment of the present invention.

[0027] Figure 1B It is a flowchart showing the main steps of another embodiment of the present invention.

[0028] Figure 2 is a calibration curve for calculating the polyethylene content in polypropylene using enthalpy values ​​from DSC measurements.

[0029] Figure 3 Schematic diagram of the experimental setup used in the dissolution, sedimentation, filtration, and separation steps. DETAILED DESCRIPTION

[0030] I. definition

[0031] As used herein, the term "plastic" refers to polymers such as polyethylene (PE), PP, PET, LLDPE, LDPE, HDPE, polyethylene copolymers, ethyl vinyl acetate copolymer (EVA), ethyl vinyl alcohol copolymer (EVOH), ethylene acrylic acid copolymer (EAA), PS, PC, PVC, styrene-butadiene-styrene (SBS), PA, etc., or mixtures thereof. Such polymers are characterized by a high molecular weight, which generally determines melt processability and solid-state mechanical properties. For the purposes of this disclosure, the terms "polymer" and "plastic" are used interchangeably, and the term "MW" refers to the weight-average molecular weight of the polymer.

[0032] As used herein, the term "recycled polymer" refers to a polymer that has been used for a previous purpose and then recovered for further processing.

[0033] As used herein, the term "post-consumer" refers to a source of material that arises after the ultimate consumer has used the material in a consumer good or product.

[0034] As used herein, the term "post-consumer recycled" (PCR) refers to material that is generated after the ultimate consumer has used the material and has placed the material in the waste stream.

[0035] As used herein, the term "post-industrial recycled" (PIR) refers to sources of materials generated during the manufacture of a good or product or prior to its use by the consumer.

[0036] As used herein, the term "fluid solvent" refers to a substance that can exist in a liquid state under specific temperature and pressure conditions. In some embodiments, the fluid solvent can be a primarily uniform chemical composition of one molecule or isomer, while in other embodiments, the fluid solvent can be a mixture of several different molecular compositions or isomers. In addition, in some embodiments of the present invention, the term "fluid solvent" can also apply to a substance at, near, or above the critical temperature and critical pressure (critical point) of the substance. It is well known to those skilled in the art that a substance above its critical point is referred to as a "supercritical fluid," which does not possess the typical physical properties (i.e., density) of a liquid.

[0037] As used herein, the term "dissolved" refers to the at least partial incorporation of a solute (polymeric or non-polymeric) into a solvent at a molecular level. Furthermore, the thermodynamic stability of a solute / solvent solution can be described by the following equation: ,in is the Gibbs free energy change of mixing of solute and solvent, is the enthalpy change of mixing, is the absolute temperature, and is the entropy of mixing. To maintain a stable solution of a solute in a solvent, the Gibbs free energy must be negative and minimized. Therefore, any combination of solute and solvent that minimizes the negative Gibbs free energy at appropriate temperature and pressure can be used in the present invention.

[0038] As used herein, the term "normal boiling point" refers to the boiling point 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).

[0039] As used herein, the term "standard enthalpy change of vaporization" refers to the enthalpy change required to transform a specified amount of a substance from liquid to vapor at the normal boiling point of the substance.

[0040] As used herein, the term "polymer solution" refers to a solution of a polymer dissolved in a solvent. The polymer solution may contain undissolved matter (e.g., at least one suspended contaminant), and thus the polymer solution may also be a "slurry" of undissolved matter suspended in a solution of the polymer dissolved in the solvent.

[0041] As used herein, the terms "sedimentation" and "sedimentation" are used interchangeably and refer to the tendency of particles within a suspension to separate from the liquid in response to a force acting on the particles, typically gravity.

[0042] As used herein, the term "suspended contaminants" refers to unwanted or undesirable components present throughout the bulk of a media of a heterogeneous mixture.

[0043] As used herein, the term "dissolved contaminants" refers to unwanted or undesirable components that are at least partially incorporated into the solvent at the molecular level.

[0044] As used herein, the term "filtration" refers to the separation of at least one dissolved contaminant and / or suspended contaminant from a fluid by the use of mechanical and / or physical manipulations (e.g., passing the contaminated fluid through a filtration system). As used herein, the terms "filtration system" and "filter" are used interchangeably.

[0045] As used herein, when referring to a solution, the term "less suspended contaminants" refers to a subsequent state of the solution relative to a previous state (eg, before a contaminant removal step), wherein the previous solution had a relatively higher amount of suspended contaminants.

[0046] As used herein, when referring to a solution, the term "containing even fewer suspended contaminants" refers to a subsequent state of a solution relative to a previous state (eg, "containing fewer suspended contaminants"), where the previous solution had a relatively greater amount of suspended contaminants.

[0047] As used herein, the term "solid medium" refers to a substance that exists in a solid state under the conditions of use. The solid medium can be crystalline, semi-crystalline, or amorphous. The solid medium can be granular and can be supplied in different shapes (i.e., spheres, cylinders, pellets, etc.). If the solid medium is granular, the particle size and particle size distribution of the solid medium can be defined by the mesh size used to classify the granular medium. Examples of standard mesh size designations can be found in the American Society for Testing and Materials (ASTM) standard ASTM E11 "Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves." The solid medium can also be a nonwoven fiber mat or a woven textile.

[0048] As used herein, the term "purer polymer solution" refers to a polymer solution that has less of one or more contaminants relative to the same polymer solution prior to a purification step.

[0049] As used herein, the term "extraction" refers to the operation of transferring a solute species from a liquid phase (or solid matrix) across a phase boundary to a separate, immiscible liquid phase. The driving force for extraction is described via partition theory.

[0050] As used herein, the term "extracted" refers to a material that is lower in one or more solute species relative to the same material prior to the extraction step. As used herein, the term "extracted regenerated polymer" refers to a regenerated polymer that is lower in one or more solute species relative to the same regenerated polymer prior to the extraction step.

[0051] As used herein, the term "virgin" means substantially free of contaminants, colorless, odorless, homogeneous, and similar in properties to virgin polymer.

[0052] As used herein, the term "primarily polypropylene copolymer" refers to a copolymer having greater than 70 mol% propylene repeating units.

[0053] As used herein, the term "primarily polyethylene copolymer" refers to a copolymer having greater than 70 mol% ethylene repeating units.

[0054] As used herein, any reference to international units of pressure (eg, MPa) refers to gauge pressure.

[0055] As used herein, the term "axial flow direction" refers to fluid flowing parallel to the long axis of the filter media.

[0056] As used herein, the term "radial flow direction" refers to fluid flow perpendicular to the long axis of the filter media.

[0057] As used herein, the term "candle filter" refers to a device that uses pressure to separate solids from liquids. A detailed description of candle filters and other solid-liquid separation equipment is provided in the following reference: Perry, Robert H. and Don W. Green. Perry, Chemical Engineers' Handbook. New York: McGraw-Hill, 2008.

[0058] As used herein, the term "pre-coated with filter aid" refers to a solid-liquid separation device in which the filter medium is composed of a rigid or semi-rigid screen having deposited thereon one or more layers of fine solid material (e.g., diatomaceous earth, perlite, cellulose fibers, clay, activated carbon, alumina, silica, aluminum silicate, zeolites, and mixtures thereof).

[0059] As used herein, the term "body feed" refers to the addition of filter aids to a fluid prior to filtering the fluid.

[0060] As used herein, the term "contaminant" refers to any undesirable material contained on the surface of or within the bulk of a plastic. The term "chemical contaminant" refers to any undesirable chemical substance on the surface of or within the bulk of a plastic and includes the molecular or elemental composition of the contaminant. The terms are used interchangeably, depending on the intent. For example, a paper contaminant includes cellulose. Therefore, cellulose is a type of chemical contaminant in paper contaminants.

[0061] As used herein, the term "pollution" refers to the sum of all pollutants, and the term "chemical pollution" refers to the sum of all chemical pollutants. Chemical pollutants are grouped into categories that include chemical pollutants with similar chemical structures. For example, As, Hg, and Cr are chemical pollutants classified as "heavy metals." Each pollutant can have different chemical properties, such as solubility and diffusivity in plastics, and target levels depend on concentration and end-use market.

[0062] As used herein, the term "surface contaminant" refers to contaminants on the surface of a plastic. Similarly, the term "surface chemical contaminant" refers to the molecular or elemental composition of the surface contaminant. Surface contaminants can be loosely attached to the plastic surface through physical attraction or more strongly attached through polarity or other forces. Typically, surface contaminants will have less than about 80% of their surface area embedded in the plastic.

[0063] As used herein, the term "bulk contaminant" refers to the contaminant in the bulk of the plastic. Similarly, the term "bulk chemical contaminant" refers to the molecular or elemental composition of the bulk contaminant. Typically, a bulk contaminant will have greater than about 80% of its surface area embedded in the plastic.

[0064] As used herein, the terms "surface contamination" and "surface chemical contamination" refer to the sum of all surface contaminants and all surface chemical contaminants, respectively.

[0065] As used herein, the terms "total pollution" and "total chemical pollution" refer to the sum of all total pollutants and all total chemical pollutants, respectively.

[0066] As used herein, the term "total contamination" refers to the sum of surface contamination and bulk contamination and the sum of all surface chemical contamination and bulk chemical contamination, respectively.

[0067] As used herein, the term "permeable contaminants" refers to chemical contaminants that are soluble and diffusible in plastics. Non-limiting examples of permeable contaminants are formaldehyde, bisphenol A, and naphthalene.

[0068] As used herein, the term "impermeable contaminants" refers to chemical contaminants that are insoluble or non-diffusible in plastics. Non-limiting examples of impermeable contaminants are heavy metals and gel particles composed of cross-linked or ultra-high MW plastics (too large to diffuse).

[0069] As used herein, the term "permeable contamination" refers to the sum of all permeable contaminants, and the term "impermeable contamination" refers to the sum of all impermeable contaminants. The sum of all permeable and impermeable contaminants is a "chemical contaminant" if described in molecular or elemental terms, or simply a "contaminant" if described in general terms (such as cellulose and paper).

[0070] As used herein, the term "intentional contaminant" refers to a contaminant that is intentionally added by the supply chain for a specific purpose to benefit the producer, retailer, or consumer, but that may not be desirable in recycled plastics. Examples include printed matter, paper labels, adhesives used for labels, pigments (such as TiO2), processing additives (such as antioxidants - AO), etc., which are necessary for marketing, branding, processability, and / or end-use performance. As used herein, the term "intentional chemical contaminant" refers to an intentional contaminant described by its chemical composition. As used herein, the term "intentional contamination" refers to the sum of all intentional contaminants, and the term "intentional chemical contamination" refers to the sum of all intentional contaminants described by their chemical composition.

[0071] As used herein, the surface area to volume ratio of a plastic is calculated as follows. For generally spherical objects, such as pellets, ground pellets, micronized pellets, etc., the surface area to volume ratio is given by 3 / r Calculate, where r is the mass mean radius. For generally flat and thin objects, such as membranes, the surface area to volume ratio is given by 2 / t Calculate, where t is the mass average thickness. For a generally long cylindrical object, such as a fiber, the surface area to volume ratio is given by 2 / r Calculated where r is the mass average radius. For the purposes of the present invention, the terms "mass average surface area to volume ratio" and "surface area to volume ratio" are used interchangeably.

[0072] As used herein, the term "unintentional contaminant" refers to any contaminant that is not intentionally added. Examples include soiling and cross-contamination that is not intentionally added by the manufacturer, retailer, or consumer. As used herein, the term "unintentional chemical contaminant" refers to an unintentional contaminant described by its chemical composition. As used herein, the term "unintentional contamination" refers to the sum of all unintentional contaminants, and the term "unintentional chemical contamination" refers to the sum of all unintentional contaminants described by their chemical composition.

[0073] As used herein, the term "densified" refers to a state of plastic in which the bulk density of the plastic is higher than that of the original / pre-densified plastic and the original surface of the plastic is reduced and / or inaccessible to wetting fluids. The process of producing a densified material is called densification.

[0074] As used herein, the term "melt densification" refers to densification near, at, or above the initial melting point of the plastic. Non-limiting methods of melt densification include melt extrusion and agglomeration using equipment such as a Herbold HV series plastic compactor.

[0075] As used herein, the term "initial melting point" refers to the peak melting point (highest endothermic peak on a zero-slope baseline) of a plastic as measured using differential scanning calorimetry (DSC). For the purposes of this disclosure, the terms "initial melting point," "melting point," "melting temperature," and "initial melting temperature" are used interchangeably. For amorphous materials and / or materials lacking a distinct melting point, the limiting temperature will be the material's approximate softening point, which can be best characterized by its glass transition temperature. Those skilled in the art will understand the appropriateness of this standard for non-semicrystalline materials.

[0076] As used herein, the term "hexane" refers to a blend of hexane isomers, such as n-hexane (at least 45% by volume, and typically about 53% by volume), isohexane (2-methylpentane, 3-methylpentane, and 2,3-dimethylbutane), and neohexane (2,2-dimethylbutane).

[0077] As used herein, the term "limit of quantitation" or "LOQ" refers to the lower limit of detection of a given chemical contaminant as determined by the analytical method disclosed in Section IX. The LOQ is a function of the method used and can vary depending on the test method. The LOQ used herein is specific to the method listed in Section IX.

[0078] As used herein, the term "removal efficiency" refers to the efficiency of the process of removing a specific pollutant, calculated as 100 × (initial concentration-final concentration) / initial concentration and expressed as a percentage. In the case where the final concentration is lower than LOQ, and for simplicity, the removal efficiency is calculated using LOQ as the final concentration, the removal efficiency is considered to be a minimum value and is designated as >. In some cases, due to 1) measurement errors, 2) pollutant hot spots and cold spots in the recycled polymer, 3) external contamination during sampling, or 4) increased pollution during the purification process, purer plastics will have higher levels of pollutants than recycled polymers. In this case, the removal efficiency is set to 0% so as not to deviate from the average result. If this happens consistently in a given process, this is more likely to be attributed to the process and should be checked more carefully, but this is not usually the case with the process of the present invention. As used herein, the term "average removal efficiency" refers to the average value of the removal efficiency of each pollutant.

[0079] II. Recycled polymers

[0080] When first produced at resin suppliers such as Dow, Nova, ExxonMobil, etc., polymers are largely free of contamination (virgin plastic). However, during the polymer's life cycle (from production to distribution, consumer use, and eventual recycling), contamination is introduced, intentionally or unintentionally.

[0081] Non-limiting examples of intentional contamination include surface printing, paper labels, adhesives used for labels, pigments (such as TiO2), processing additives (such as AO), etc., which are necessary for marketing, branding, processability, and / or end-use performance. Non-limiting examples of unintentional contamination include dirt, cross-contamination, certain heavy metals, pesticides, dioxins, furans, PCBs, etc. Furthermore, unintentional contamination can result from reactions involving intentional contaminants, such as the oxidation of paper labels to dioxins, or the degradation of adhesives or printing binders. Most of the latter occurs during the melt densification process used in recycling. Furthermore, during melt processing steps (such as those used for original packaging or product manufacturing and / or subsequent recycling), oxidation of plastics can produce unintentional contamination, such as gels. Furthermore, unintentional contamination can arise from interactions with products. For example, packaging materials containing cleaning compounds (e.g., limonene, surfactants, etc.) or foods (e.g., various organic substances) are potentially contaminated by such products. Finally, unintentional contamination can enter plastics during production, for example, by contaminating the plastic with reaction byproducts, unreacted monomers, etc.

[0082] It should be recognized that different recycled polymer sources have different contamination and associated risks. Obviously, recycled polymer streams of unknown origin and life cycle will be the most abundant, but also represent the highest potential for contamination. On the other hand, controlled recycled polymer streams are available and present a lower potential risk for demanding applications. For example, if a recycled polymer stream is known to come from a demanding application, such recycled polymer stream will not contain any undesirable contaminants until distributed to consumers, otherwise these plastics will not be approved for use in these applications. Therefore, the contamination that prevents reuse in these same applications is primarily unintentional contamination, which must originate from external sources and enter the plastic through surface contamination. Small amounts of contamination may be caused by reactions involving intentional contamination, such as the oxidation of cellulosic materials to dioxins during melt densification.

[0083] Pre-consumer plastic generally has the lowest contamination levels due to its known composition and controlled history. It can include intentional contamination such as surface printing and opacifiers, but because these are known and controlled, it is very easy to find applications that tolerate such known contaminants. In addition, due to its controlled history, pre-consumer plastic tends to have low levels of unintentional contamination, thus preventing external contamination. Therefore, pre-consumer plastic originally intended for demanding applications would be an ideal source of recycled polymer for the same end market with minimal cleaning / purification. This latter pre-consumer plastic in film form is known as "Approved Source Post-Industrial Film" (ASPIF). On the downside, ASPIF streams are very limited in supply and do not support circularity.

[0084] Post-consumer plastics are generally more contaminated than pre-consumer plastics. Given their somewhat more controlled lifecycle within the commercial supply chain, the post-commercial sub-category of post-consumer plastics has the second-lowest contamination levels relative to pre-consumer recycling. Typically, post-commercial recycled plastics will have known and controlled levels of intentional contamination, enabling widespread use as recycled polymer. However, unintentional contamination is known to be common, and this stream presents issues that hinder widespread use in demanding applications. Post-commercial plastics sourced from demanding applications can potentially be returned to these fields after adequate cleaning / purification. Post-commercial plastics sourced from demanding applications in film form are referred to as "Approved Source Post-Commercial Film" (ASPCF). To accommodate the ongoing demand for purer recycled polymers, recycled material suppliers have recently introduced sources of post-commercial film with more controlled and known histories. These new sources are referred to as high-security sources and are primarily used with post-commercial film streams. Therefore, high-security sources should have reduced contamination levels relative to typical post-commercial film sources. On the downside, these high-security sources are limited in volume and are more expensive.

[0085] The post-consumer, post-home subcategory has the highest levels of contamination, given its uncontrolled lifecycle within the commercial channel. This plastic has high levels of intentional and unintentional contamination that are highly variable, unknown, and uncontrolled. This plastic can include sources of plastic that were originally not suitable for demanding applications. Consequently, the market for this source of plastic is limited and essentially nonexistent in demanding applications.

[0086] Surprisingly, the purer plastics produced by the present invention may allow plastics from post-industrial sources (ASPIF and uncontrolled sources), post-commercial sources (ASPCF and uncontrolled sources), and post-domestic sources to be more widely used in demanding applications with some restrictions. Furthermore, most consumers of recycled materials demand purer materials than are currently available, and the purer plastics of the present invention meet this broader demand for purer plastics from any source.

[0087] For purposes of the present invention, non-limiting examples of polymers are films, sheets, injection molded parts, blow molded parts, fibers, nonwovens, wovens, thermoformed parts, and extruded strands.

[0088] The recycled polymer can be a first-life plastic (used only once before entering the recycled polymer stream), a second-life plastic (used twice before entering the recycled polymer stream), or a higher-life plastic (used multiple times before entering the recycled polymer stream). In embodiments of the present invention, the recycled polymer comprises virgin plastic. In embodiments of the present invention, the recycled polymer comprises a film. In embodiments of the present invention, the recycled polymer is selected from the group consisting of a film, an injection molded part, a blow molded part, a fiber, a nonwoven, a woven, a thermoformed part, an extruded strand, or mixtures thereof.

[0089] In an embodiment of the present invention, the recycled polymer comprises regrind / offcuts / in-plant scrap plastic. In an embodiment of the present invention, the recycled polymer comprises PIR polymer. In an embodiment of the present invention, the recycled polymer comprises PIR polymer film. In an embodiment of the present invention, the recycled polymer comprises PIR polymer nonwoven. In an embodiment of the present invention, the PIR polymer film is ASPIF. In an embodiment of the present invention, the recycled polymer comprises PCR polymer. In an embodiment of the present invention, the recycled polymer comprises PCR polymer film. In an embodiment of the present invention, the recycled polymer comprises PCR polymer nonwoven. In an embodiment of the present invention, the PCR polymer film is ASPCF. In an embodiment of the present invention, the recycled polymer comprises high-shelf PCR polymer film. In an embodiment of the present invention, the recycled polymer comprises post-domestic polymer. In an embodiment of the present invention, the recycled polymer comprises post-domestic polymer film. In an embodiment of the present invention, the recycled polymer comprises post-domestic polymer nonwoven.

[0090] In an embodiment of the present invention, the recycled polymer comprises PS, copolystyrene, PA, copolyamide, PC, thermoplastic elastomer, styrene block copolymer, polyester, copolyester, PVC, copolymers of any of the foregoing, and mixtures of any of the foregoing. In an embodiment of the present invention, the recycled polymer comprises polyolefins, polyolefin copolymers, and polyolefin polar copolymers. In an embodiment of the present invention, the recycled polymer comprises LDPE and LLDPE copolymers. In an embodiment of the present invention, the recycled polymer comprises PP. In an embodiment of the present invention, the recycled polymer comprises HDPE and HDPE copolymers. In an embodiment of the present invention, the recycled polymer comprises a film, and the film comprises polyethylene and a polyethylene copolymer.

[0091] In an embodiment of the present invention, the recycled polymer is a PCR polymer. In an embodiment of the present invention, the recycled polymer is a polypropylene homopolymer or a primarily polypropylene copolymer. In an embodiment of the present invention, the recycled polymer is a polyethylene homopolymer or a primarily polyethylene copolymer. In an embodiment of the present invention, the method for purifying the recycled polymer comprises obtaining a recycled polymer; and wherein the recycled polymer is selected from a PCR polymer, a PIR polymer, and combinations thereof. The recycled polymer can be in many forms, including but not limited to pellets, micronized pellets, ground pellets, chopped film, chopped or ground injection molded parts, chopped or ground blow molded parts, thermoformed parts, chopped nonwovens or wovens, extruded strands, or agglomerated particles. In an embodiment of the present invention, the recycled polymer comprises pellets.

[0092] In an embodiment of the present invention, the recycled polymer has a thickness greater than about 1 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of greater than about 5 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of greater than about 20 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of greater than about 50 mm -1 The average surface area to volume ratio.

[0093] For purposes of the present invention, recycled polymers are derived from post-consumer, post-industrial, post-commercial, and / or other specialized recycled waste streams. For example, PCR polymers can be derived from curbside recycling streams, where end consumers place used polymers from packaging and products into designated bins for collection by garbage trucks or recyclers. PCR polymers can also be derived from in-store "take-back" programs, where consumers bring waste polymers into the store and place the waste polymers in designated collection bins. Examples of PIR polymers can be waste polymers generated during the manufacture or transportation of goods or products that are collected by manufacturers as unusable material (i.e., trimmings, out-of-spec materials, start-up waste). An example of waste polymers from specialized waste streams can be waste polymers derived from the recycling of electronic waste (also known as "e-waste"). Another example of waste polymers from specialized waste streams can be waste polymers derived from the recycling of automobiles. Another example of waste polymers from specialized waste streams can be waste polymers derived from the recycling of used carpets and textiles.

[0094] For the purposes of the present invention, a recycled polymer is a homogeneous composition of a single polymer or a mixture of several different polymer compositions. Non-limiting examples of recycled polymer compositions are homopolymers and copolymers of polyolefins such as polyethylene and isotactic polypropylene; polyesters such as polyethylene terephthalate; vinyl polymers such as polyvinyl chloride; styrene polymers such as polystyrene; polyamides such as poly(hexamethylene adipamide); polycarbonates such as poly(bisphenol A carbonate); polyacrylates such as poly(methyl methacrylate); polysiloxanes such as polydimethylsiloxane; thermoplastic elastomers such as styrene-butadiene block copolymers and ethylene-propylene rubber; and other soluble polymers that may be apparent to one of ordinary skill in the art.

[0095] Recycled polymers may also contain various pigments, dyes, processing aids, stabilizing additives, fillers, and other performance additives that are added to the polymer during the polymerization of the original polymer or its conversion into the final form of the product. Non-limiting examples of pigments are organic pigments such as copper phthalocyanine, inorganic pigments such as titanium dioxide, and other pigments that may be apparent to those of ordinary skill in the art. A non-limiting example of an organic dye is Basic Yellow 51. Non-limiting examples of processing aids are antistatic agents such as glyceryl monostearate and slip agents such as erucamide. A non-limiting example of a stabilizing additive is octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate. Non-limiting examples of fillers are calcium carbonate, talc, and glass fiber.

[0096] III. pollutants

[0097] Pollutants can be generally decomposed into two migration categories: 1) permeable; and 2) impermeable. Permeable pollutants have solubility and diffusivity in the regenerated polymer to allow migration into, through, and from the polymer due to the chemical potential gradient. In other words, permeable pollutants and the grouping called permeable pollution are removable. Impermeable means that the pollutant does not have enough solubility and diffusivity to significantly move into, through, and from the polymer. In other words, the impermeable pollution represented by the sum of all impermeable pollutants is basically fixed. Therefore, no matter where the impermeable pollutant is first deposited, this type of pollution will remain in this position until physically removed, convectively transferred, or placed in contact with different materials that are permeable to the pollutant.

[0098] Chemical contaminants in recycled polymers can be diverse, but typically fall into one of several related chemical categories. Non-limiting examples of related chemical categories are pesticides, aldehydes, allergic fragrances, izioaline, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, organotin compounds, metals, phthalates, and polycyclic aromatic hydrocarbons (PAHs). Only some of these chemical categories, such as pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, metals, organotin compounds, phthalates, and PAHs, are routinely found in pre-consumer and post-consumer recycled polymers.

[0099] Using the analytical methods disclosed in Section IX, the LOQs for various contaminants can vary by several orders of magnitude. For example, the LOQ for a typical pesticide is about 10 ppb; the LOQ for a typical alkylphenol ethoxylate is about 50 ppb; the LOQ for a typical alkylphenol is about 5 ppb; the LOQ for bisphenol A is about 5 ppb; the LOQ for a typical dioxin is about 0.2 ppt; the LOQ for a typical furan is about 0.2 ppt; the LOQ for a typical PCB is about 5 ppt; the LOQ for a typical heavy metal is about 100 ppb; the LOQ for a typical organotin is about 300 ppt; the LOQ for a typical phthalate is 50 ppb; and the LOQ for a typical PAH is 1 ppb.

[0100] As shown in Tables 1a-1i, using the analytical methods disclosed in Section IX, several membrane sources were broadly categorized for chemical contamination, including three ASPIF sources, three high-security commercial post-membrane sources, three commercial post-membrane sources, and one residential post-membrane source. To simplify the presentation of chemical contamination results, concentration data are presented as LOQ rather than absolute weight fraction. For example, if the contaminant concentration is 10 ppm and the LOQ is 1 ppm, the concentration would be 10 × LOQ or simply 10 in the data table. Additionally, "dnt" stands for "not tested."

[0101] Table 1a-1i

[0102] Chemical contamination from ASPIF, High-Care Post-Commercial (HCPC), Post-Commercial (PC), and Post-Household (PH) membrane sources

[0103] Table 1a

[0104] Chemical pollution - pesticides

[0105] Table 1b

[0106] Chemical pollution - alkylphenol ethoxylates

[0107] Table 1c

[0108] Chemical pollution-alkylphenol

[0109] Table 1d

[0110] Chemical pollution-bisphenol

[0111] Table 1e

[0112] Chemical pollution - dioxins, dioxin-like substances, furans and PCBs

[0113] Table 1f

[0114] Chemical pollution-metal

[0115] Table 1g

[0116] Chemical pollution-organic tin

[0117] Table 1h

[0118] Chemical pollution-phthalates

[0119] Table 1i

[0120] Chemical pollution-PAH

[0121] The ASPIF sources tested were largely free of detectable levels of chemical contaminants, with the exception of alkylphenols and heavy metals, and small amounts of organotins and PAHs. The chemical contamination results for these ASPIF sources serve as a guide to chemical contamination levels representative of these controlled end markets and demonstrate that heavy metals, however, with a low risk of transfer, are prevalent in all membrane sources. Therefore, heavy metals were not included in the ongoing analysis within this application. The high-security commercial post-membrane sources tested were largely free of pesticides and alkylphenol ethoxylates, but contained detectable levels of alkylphenols, bisphenol A, dioxins / furans / PCBs, and PAHs, as well as low levels of phthalates. The commercial post-membrane sources tested were heavily contaminated in every category evaluated; for example, dioxins were generally as high as 40×LOQ, but for one source, dioxins were as high as 200×LOQ. The domestic post-membrane sources tested were the most heavily contaminated; for example, dioxins were as high as 300×LOQ, and PCBs were as high as 180×LOQ.

[0122] From Tables 1a-1i, representative chemicals were selected from various categories based on their prevalence in the spectrum of recycled polymer sources. The chemicals selected within these categories are: piperonyl butoxide (indicating pesticides); 4-tert-octylphenol hexaethoxylate and isononylphenol triethoxylate (indicating alkylphenol ethoxylates); isononylphenol and 4-tert-amylphenol (indicating alkylphenols); bisphenol A (indicating phenols); 1.2.3.6.7.8-HxCDD, 1.2.3.4.6.7.8-HpCDD, and OCDD (indicating dioxins); OCDF (indicating furans); PCB 105 and PCB 118 (indicating PCBs); monobutyltin and dibutyltin (indicating organotins); dibutyl phthalate and di-2-ethylhexyl phthalate (indicating phthalates); fluoranthene and phenanthrene (indicating PAHs) (Table 2).

[0123] In an embodiment of the present invention, the chemical contaminants in the recycled polymer include at least one chemical contaminant, and the chemical contaminant is selected from the group consisting of pesticides, alkylphenols, alkylphenol ethoxylates, bisphenols, dioxins, furans, PCBs, phthalates, PAHs, or mixtures thereof.

[0124] In an embodiment of the present invention, the pesticides include piperonyl butoxide, BAC, DEET, and DDAC. In an embodiment of the present invention, the alkylphenol ethoxylates include isononylphenol monoethoxylate, isononylphenol diethoxylate, isononylphenol triethoxylate, and isononylphenol tetraethoxylate. In an embodiment of the present invention, the alkylphenols include isononylphenol, 4-tert-butylphenol, and 4-tert-amylphenol. In an embodiment of the present invention, the bisphenols include bisphenol A. In an embodiment of the present invention, the dioxins include 1,2,3,6,7,8-HxCDD, 1.2.3.4.6.7.8-HpCDD, and OCDD. In an embodiment of the present invention, the furans include OCDF. In an embodiment of the present invention, the PCBs include PCB 77, PCB 81, PCB 126, PCB 105, PCB 114, PCB 118, PCB 123, PCB 156, and PCB 167. In an embodiment of the present invention, phthalates include di-2-propylheptyl phthalate, diisobutyl phthalate, dibutyl phthalate, di-1-ethylhexyl phthalate, and diisononyl phthalate. In an embodiment of the present invention, PAHs include acenaphthene, acenaphthene, anthracene, benz[a]anthracene, benzo[b]fluoroanthracene, benzo[e]pyrene, benzo[ghi]perylene, chrysene, cyclopenta[cd]pyrene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene. In an embodiment of the present invention, organotin includes monobutyltin, dibutyltin, and dioctyltin.

[0125] In an embodiment of the present invention, the contaminants in the recycled polymer may include 4-tert-amylphenol. In an embodiment of the present invention, the contaminants in the recycled polymer may include bisphenol A. In an embodiment of the present invention, the contaminants in the recycled polymer may include OCDD. In an embodiment of the present invention, the contaminants in the recycled polymer may include PCB 118. In an embodiment of the present invention, the contaminants in the recycled polymer may include di-2-ethylhexyl phthalate.

[0126] To simplify the presentation of the purification results for the present invention and related examples, the number of chemicals presented per chemical class is limited to the representative chemicals listed above for each chemical class, as shown in Table 2, along with the associated LOQs and corresponding levels for the ASPIF sources tested. While more in-depth and complete chemical analyses were performed for all of the present invention's objectives, only selected chemicals are consistently presented. This simplification does not affect or alter the present invention or the conclusions drawn therefrom. The selected chemicals adequately and consistently represent the broader categories of purification.

[0127] Table 2

[0128] Selected chemical contaminants and associated LOQ concentrations

[0129] In embodiments of the invention, the concentration of each pesticide in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable pesticide. In embodiments of the invention, the concentration of bisphenol A in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least detectable bisphenol A. In embodiments of the invention, the concentration of each dioxin in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable dioxin. In embodiments of the invention, the concentration of each PCB in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable PCB. In embodiments of the invention, the concentration of each phthalate in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable phthalate.

[0130] In an embodiment of the present invention, the concentration of piperonyl butoxide in the purer plastic is less than about 10 ppb; wherein the concentration of piperonyl butoxide in the recycled polymer is greater than 10 ppb; the concentration of 4-tert-amylphenol in the purer plastic is less than about 5 ppb; wherein the concentration of 4-tert-amylphenol in the recycled polymer is greater than 5 ppb; the concentration of bisphenol A in the purer plastic is less than about 5 ppb; wherein the concentration of bisphenol A in the recycled polymer is greater than 5 ppb; the concentration of OCDD in the purer plastic is less than about 0.2 ppt; wherein the concentration of OCDD in the recycled polymer is greater than 0.2 ppt; the concentration of PCB 118 in the purer plastic is less than about 10 ppt; wherein the concentration of PCB 118 in the recycled polymer is greater than 10 ppt; the concentration of di-2-ethylhexyl phthalate in the purer plastic is less than about 50 ppb; wherein the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than 50 ppb.

[0131] In an embodiment of the present invention, the removal efficiency of the piperonyl butoxide contaminant is greater than 55%; and the concentration of the piperonyl butoxide in the recycled polymer is at least 10 ppb. In an embodiment of the present invention, the removal efficiency of the piperonyl butoxide contaminant is greater than 85%; and the concentration of the piperonyl butoxide in the recycled polymer is greater than about 10 ppb.

[0132] In an embodiment of the present invention, the removal efficiency of 4-tert-amylphenol contaminant is greater than 55%, wherein the concentration of 4-tert-amylphenol in the recycled polymer is at least 5 ppb. In an embodiment of the present invention, the removal efficiency of 4-tert-amylphenol contaminant is greater than 85%, wherein the concentration of 4-tert-amylphenol in the recycled polymer is at least 5 ppb.

[0133] In an embodiment of the present invention, the removal efficiency of bisphenol A contaminants is greater than 55%, and the concentration of bisphenol A in the recycled polymer is at least 5 ppb. In an embodiment of the present invention, the removal efficiency of bisphenol A contaminants is greater than 79%, and the concentration of bisphenol A in the recycled polymer is greater than about 5 ppb.

[0134] In an embodiment of the present invention, the removal efficiency of OCDD contaminants is greater than 55%, and the concentration of OCDD in the recycled polymer is greater than about 0.2 ppt. In an embodiment of the present invention, the removal efficiency of OCDD contaminants is greater than 95%, and the concentration of OCDD in the recycled polymer is greater than about 0.2 ppt.

[0135] In an embodiment of the present invention, the removal efficiency of OCDF contaminants is greater than 55%, and the concentration of OCDF in the recycled polymer is greater than about 0.2 ppt. In an embodiment of the present invention, the removal efficiency of OCDF contaminants is greater than 93%, and the concentration of OCDF in the recycled polymer is greater than about 0.2 ppt.

[0136] In an embodiment of the present invention, the removal efficiency of PCB 118 contaminants is greater than 55%, and the concentration of PCB 118 in the recycled polymer is at least 10 ppt. In an embodiment of the present invention, the removal efficiency of PCB 118 contaminants is greater than 66%, and the concentration of PCB 118 in the recycled polymer is greater than about 10 ppt.

[0137] In an embodiment of the present invention, the removal efficiency of di-2-ethylhexyl phthalate contaminant is greater than 55%, and the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb. In an embodiment of the present invention, the removal efficiency of di-2-ethylhexyl phthalate contaminant is greater than 78%, and the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb.

[0138] In an embodiment of the present invention, the removal efficiency of the phenanthrene pollutant is greater than 55%, and the concentration of the phenanthrene in the recycled polymer is at least 1 ppb. In an embodiment of the present invention, the removal efficiency of the phenanthrene pollutant is greater than 93%, and the concentration of the phenanthrene in the recycled polymer is at least 1 ppb.

[0139] Contamination can be located on the surface of the plastic or in the bulk. Contamination on the surface is most conveniently and easily removed by surface cleaning technologies currently available on the market. If the surface contamination in the plastic is permeable, it will become bulk contamination over time through a diffusion mechanism, thus complicating reduction and limiting the effectiveness of surface cleaning technologies. If the surface contamination is impermeable in the plastic, such contamination will not diffuse into the bulk and will be reduced by simple surface cleaning methods such as aqueous washing. Bulk contamination of either permeable or impermeable types cannot usually be effectively removed by simple surface purification methods such as aqueous washing. Bulk contamination of impermeable types (also referred to as bulk impermeable contamination) is trapped in the bulk plastic and can be released by mechanisms including melt convection, melt filtration, or dissolution / decomposition of the bulk plastic.

[0140] As previously discussed, contamination can be introduced from the outside throughout the life cycle of the plastic. If the contamination is impermeable, such contamination will largely remain on the surface during the life cycle of the plastic until it is recycled. If the contamination is permeable, the contamination will migrate into the entire plastic over time. Therefore, in the absence of contamination or purification events, the contamination will remain essentially constant, but the balance between surface and overall contamination will change over time, but will approach equilibrium over a long period of time. Typically, loosely bound surface contamination such as dirt can be 0.01% by weight to about 0.1% by weight; while chemical contamination, especially the chemical contaminants to which the present invention relates, will be at ppm, ppb or even ppt levels.

[0141] Permeable and impermeable contamination present different challenges in demanding applications. For example, permeable contamination, whether within the bulk plastic or on its surface, has the potential to migrate to uncontaminated materials such as the product or human skin. Therefore, if packaging contains permeable contaminants, such contaminants have the potential to migrate into the product, rendering it unsuitable for these demanding end-use markets. However, if the contaminant is impermeable and within the bulk of the plastic, it has a low potential to transfer to the product or the user's skin unless the bulk plastic is decomposed or ingested. Therefore, packaging can potentially utilize such contaminated plastic materials without risk of contamination transfer to the product or directly to the skin. However, if the contaminant is impermeable and on the surface of the plastic, such contaminants have the potential to transfer to the product or skin through direct contact, making them unacceptable for use in these demanding applications. Both permeable and impermeable surface contamination can be converted to bulk contamination through convective mechanisms such as melt mixing and melt densification. These processes exchange or eliminate surface area with the bulk material. In the present invention, the surface contamination of the film of the present invention is converted into the film of the present invention.For example, if the film melt densification or melt extrusion of surface contamination is densified or melt-extruded into different shapes, such as pellets, then all original surface contamination will become overall contamination, no matter whether it is impermeable, and this type of overall contamination will be more difficult to remove with purification method. Melt densification is common in the recycling industry. It is also common to crush the plastics entering in the recycling industry. The latter method is not converted into overall contamination usually. Ideally, surface purification methods such as surface washing occur on the original contaminated surface such as shredded film, and wherein all original surface areas are all accessible by surface washing fluid.

[0142] Typically, it is difficult to distinguish between surface and bulk contamination using analytical methods. Most analytical methods for permeable chemical contaminants involve solvent extraction of the contaminant from the plastic over extended periods of time greater than 6 hours and exposure to extreme solvent-to-plastic mass ratios greater than 100:1, followed by quantification of the contaminant in the solvent using methods such as gas chromatography-mass spectrometry (GC-MS). Such analytical methods quantify contamination but do not distinguish between surface and bulk contamination. The efficiency of a purification process for removing surface contamination can be estimated based on the difference in contamination before and after the surface cleaning step, but this assumes that bulk contamination is not significantly affected, which may be the case when washing surfaces with the aqueous surface washing fluids discussed in this invention. A more accurate way to quantify surface contamination is to wash, then solvent extract the contaminant at different times, and then extrapolate the amount of contaminant removed over infinitesimal times, which will approximate the amount of surface contamination. However, this method is time-consuming and costly, particularly for contaminants that are typically difficult to measure. Furthermore, because the equilibrium between surface and bulk contaminants is dynamic, quantification is difficult without reference to precise sampling times. A simple method for quantifying general surface contamination (not chemical surface contamination or substance-based chemical contamination) is to weigh the regenerated polymer before and after the surface washing step.

[0143] In general, bulk contamination will not be significantly removed by simple aqueous surface washing. Permeable bulk contamination can be removed by diffusion mechanisms via chemical potential gradients. While bulk impermeable contamination is essentially trapped by the bulk polymer, methods for releasing the trapped contaminant include melt convection, melt filtration, and dissolution / disintegration of the plastic.

[0144] 1. In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer contains contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates. In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer contains contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. In an embodiment of the present invention, the alkylphenols, bisphenols, dioxins, PCBs, and phthalates include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate.

[0145] IV. Surface purification

[0146] Surface purification reduces surface contamination. A kind of such method is to carry out surface washing with the surface washing fluid of water base normally.Surface washing is ideally completed before any melt mixing or melt densification, to allow to effectively clean the original contaminated surface. Regenerated polymer is generally in the form of pellet, loose or compacted film, loose or compacted flexible packaging, loose or compacted rigid material, loose or compacted nonwoven fabric etc., and it is difficult to carry out surface washing because overall size is too large. Therefore, before surface washing, preferably granulate or chopping step. For film, it is particularly important to peel off all available film layers so that washing fluid can approach all original surface contamination. Therefore, the size reduction step before surface washing should not significantly reduce the average surface area and volume ratio of regeneration source, or exchange with new surface area.

[0147] In an embodiment of the present invention, the surface washing of the regenerated polymer is performed after the chopping or pelletizing step. Surface washing will include significant mechanical agitation to loosen surface dirt and other contaminants, thereby allowing physical removal and transfer to a washing fluid, where the dirt or other contaminants may or may not be dissolved.

[0148] As used herein, in the surface washing step, the recycled plastics that is in its original contaminated form (except not eliminating the possibility that the volume size that exceeds 25% of original surface reduces) contacts with aqueous solution under mechanical agitation, then separates with the aqueous medium that now contains this type of pollution.Such surface washing step will remove most of the loosely bound surface pollution usually, includes but not limited to dirt, timber, loosely bound paper and some surface chemical pollutions.The typical level of the loosely bound surface pollution based on the regeneration source of membrane is between about 0.01 % by weight and 0.1 % by weight.In embodiments of the present invention, surface washing will remove the loosely bound surface pollution that is greater than about 80%.

[0149] Surface washing technologies are widely available on the market. One technology is from Lindner (Lindner Washtech GmbH, Häldenfeld 4, Germany). This technology is described in detail elsewhere (https: / / www.lindner-washtech.com / system-solutions) but involves water washing under vigorous mechanical agitation and the application of caustic soda to remove binders, followed by drying and granulation. Another technology is from Herbold (Herbold Meckesheim USA, North Smithfield, RI). This technology is described in detail elsewhere (https: / / www.herbold.com / en / machines / washing-separating-drying-2 / ) and also involves various water washing steps under vigorous mechanical agitation, followed by drying and granulation. Another technology is from Sorema (Sorema Srl, Anzano del Parco, Italy). This technology is described in detail elsewhere (http: / / sorema.it / en_US / applications / washing-line / ) but involves similar aqueous procedures to those of the Lindner and Herbold technologies. Finally, another technology, from Cadel, is called deinking (Cadel Deinking, Alicante, Spain). This technology is described elsewhere (http: / / cadeldeinking.com / en / ), but essentially involves surface washing of the material using a high-temperature, water-based solution containing a specific surfactant, followed by a water rinse and drying. The process may optionally include densification, melt filtration, devolatilization, and granulation after the surface washing. This method differs from other known methods in that it requires removal of the surface printing ink. This is advantageous because the burden of removing chemical contaminants is reduced by the overall purification method of the present invention.

[0150] Three existing surface scrubbing technologies were evaluated for average removal efficiencies of five selected contaminants (Comparative Examples 1, 2, and 3). Each surface scrubbing technology was evaluated using different regenerated membranes with varying levels of contamination. Overall, existing surface scrubbing technologies were unable to adequately purify the regenerated polymer for use in controlled end-use markets. Despite low initial contamination of the corresponding regenerated polymer, the commercial technologies were unable to achieve removal near the LOQ for the selected contaminants. Furthermore, the average removal efficiencies for 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate were less than approximately 55%.

[0151] In an embodiment of the present invention, prior to the leaching step, the regenerated polymer is surface washed in a non-densified state in a surface washing step to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination of greater than about 80%. In an embodiment of the present invention, prior to the leaching step, the regenerated polymer is surface washed in a non-densified state in a surface washing step to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination of greater than about 80%; wherein the regenerated polymer has a particle size of greater than about 1 mm prior to surface washing. -1 wherein the surface washing process is of the deinking type; and wherein the deinking process results in a ΔE variation of less than about 10% between the deinked polymer and the recycled polymer without surface printing ink.

[0152] V. Melt Densification

[0153] Assuming the surface purification temperature is below the initial melting point of the recycled polymer, the plastic emerging from the surface purification step will typically have a similar geometry and a similar average surface area to volume ratio as the incoming recycled polymer. For example, if the recycled plastic is a loose film, then after shredding and surface washing at a temperature below the initial melting point of the recycled polymer, the film will exit the surface purification as a shredded film. Because such loose plastics are difficult to feed into certain bulk purification methods, such as liquid-liquid extraction, it may be desirable to densify such plastic melts prior to bulk purification.

[0154] The preferred method for melt densification is melt extrusion. Melt extrusion not only densifies the plastic, but it can also provide the pressure required for downstream overall purification such as liquid-liquid extraction. Melt extrusion can also include optional steps such as melt filtration and / or devolatilization to remove bulk contaminants and / or volatile bulk contaminants. In addition, the melt-densified plastic can be further pressurized using a melt pump. A melt pump may be required to increase the pressure required for the downstream overall purification step. Other densification methods are known in the art, including rotary disc and rotary drum densifiers, which are performed at lower temperatures relative to melt-based methods.

[0155] In an embodiment of the present invention, the melt densification comprises melt extrusion. In an embodiment of the present invention, the melt extrusion comprises melt filtration. In an embodiment of the present invention, the melt extrusion comprises melt devolatilization. In an embodiment of the present invention, the melt extrusion comprises melt pumping. In an embodiment of the present invention, the melt densification comprises melt extrusion, melt filtration, melt devolatilization, and melt pumping.

[0156] VI. Immersion and Leaching

[0157] Unexpectedly, it has been discovered that the submerged leaching step (disclosed in this Section VI) or the combined surface purification and submerged leaching step (disclosed in Section VII) in combination with the purification process (disclosed in Section VIII) produces a purer polymer from the recycled polymer with much greater efficiency than when the purification process is used alone. While not wishing to be bound by any theory, the applicant hypothesizes that removing contaminants in the leaching step results in a more efficient removal of remaining contaminants in the various steps of the purification process than when the leaching step or the surface purification and leaching steps are not present. While not wishing to be bound by any theory, the applicant believes that in the absence of the leaching step or the surface purification and leaching steps, surface contaminants of the recycled polymer become bulk contaminants, and therefore they become difficult to remove in the various steps of the purification process.

[0158] In general, bulk contamination will not be significantly reduced by simple aqueous surface washing. Melt filtration and melt devolatilization will have the potential to remove large geometric bulk contaminants and remove some volatile bulk contaminants, but will be largely ineffective for most bulk contaminants, especially at the levels required.

[0159] One commercial technology used for bulk purification is the InterRema Refresher from EREMA TM (EREMA Group, Ansfelden, Austria; https: / / www.erema.com / en / refresher / ). This technology is described in detail elsewhere, but essentially involves devolatilizing the pelletized material to remove volatile organic compounds at a temperature below the initial melting point of the plastic for an extended period of time. Most of the chemical contaminants associated with recycled polymers and discussed in the previous section are highly nonvolatile, with normal boiling points typically above 200°C. Therefore, this type of devolatilization technology will have limited ability to remove most of the chemical contaminants mentioned in this application.

[0160] Other technologies based on devolatilization are common. These can be stand-alone unit operations or combined with other operations including extrusion and melt filtration. Those that utilize subambient pressures above the molten stream of recycled plastic are common. One overall purification technology involving devolatilization was analyzed for its purification capabilities. This technology involves slightly elevated temperatures but below the initial melting point of the plastic, long residence times (greater than about 2 hours), and continuous reflux of purified air to provide devolatilization (Comparative Example 4). The commercial devolatilization technology was unable to adequately remove the selected contaminants. For example, the selected contaminants remained well above the LOQ, and the average removal efficiency was about 41%.

[0161] Extraction is the preferred overall purification method. Extraction involves the use of a purified solvent to remove bulk permeable contaminants by creating a chemical potential gradient between the regenerated polymer and the solvent. The rate of removal of permeable chemical contaminants will depend on the contaminant's diffusivity and solubility in the plastic under the conditions generated in the method. For high-MW plastics, the diffusivity of large molecules indicative of chemical contaminants is very low, especially in the plastic's solid state. In addition, solubility may be limited by the high MW of the regenerated polymer and the lack of enthalpic mixing. Therefore, the time required to remove permeable contaminants by diffusion mechanisms can be quite long and unsuitable for an economically viable process on a commercial scale. Approaches to address these timescale limitations include 1) increasing diffusivity through elevated temperature and / or increasing plastic relaxation through solvent swelling, 2) reducing the diffusion path length by increasing the average surface area to volume ratio of the regenerated polymer exposed to the solvent, and 3) increasing convective transport of contaminants across the plastic / solvent interface by increasing the contaminant's solubility in the solvent, increasing the partitioning of the contaminant in the solvent relative to the plastic, increasing convection to the plastic / solvent interface, and increasing the solvent reservoir relative to the plastic reservoir. The solubility of the bulk purification solvent in the plastic can be increased by operating the extraction at elevated pressure, particularly at, near or above the critical pressure.

[0162] Importantly, the extraction method is scalable to large volumes at low cost. Therefore, the time required for extraction should be short to allow for this scalability. In embodiments of the present invention, the total extraction time is less than about 6 hours, preferably less than about 4 hours, more preferably less than about 2 hours, and even more preferably less than about 1 hour. If the extraction is performed in stages, the time for each stage may be less than this range, but the total time will still fall within these times.

[0163] Extraction can be performed above, near, at, or below the initial melting point of the recycled polymer. Extraction performed at, near, or above the initial melting point of the recycled polymer is known as liquid-liquid extraction. Extraction performed below the initial melting point of the recycled polymer is known as leaching extraction, or simply the leaching process. The extraction solvent used in leaching extraction is known as the leaching solvent.

[0164] In the submerged leaching step of the present invention, the regenerated polymer is contacted with excess solvent at each stage and for each time period of the step. This leaching process is referred to as a submerged leaching process. For the purposes of the present invention, "submerged leaching" and "leaching" are used interchangeably. Furthermore, for the purposes of the present invention, "process," "step," "process step," and their plural forms are used interchangeably.

[0165] In the leaching step, the mass of the leaching solvent to the mass of the regenerated polymer exposed to the solvent at each time point and in each stage of the process is preferably equal to or greater than about 5:1. In some leaching steps, the solvent is rapidly stirred so that the regenerated polymer remains suspended in the solvent even when the density of the regenerated polymer is greater than that of the solvent. This type of leaching step ensures complete contact between the surface of the regenerated polymer and the leaching solvent and reduces mass transfer resistance within the solvent boundary layer surrounding the regenerated polymer surface due to convective motion. In addition to stirring, a similar reduced boundary layer can be achieved in the submerged leaching step by allowing the regenerated polymer to settle through the solvent in a density gradient. Examples of submerged leaching steps include continuous (also known as continuously stirred tank reactors - CSTRs), semi-continuous, and batch types of stirred tanks. Additional examples of submerged leaching steps include settling tanks, in which the regenerated polymer is allowed to settle out or pass through the solvent filled in a tank or other container. Applicants have found that for the submerged leaching step of the present invention, the mass ratio of leaching solvent to recycled polymer at any point in time and at any stage should preferably be greater than about 5:1, more preferably greater than 10:1 per stage, and most preferably greater than about 20:1, to enable the recycled polymer to be fully dispersed and exfoliated within the leaching solvent.

[0166] In an embodiment of the present invention, the submerged leaching step is performed in a stirred tank. In an embodiment of the present invention, the submerged leaching step is performed in a CSTR. In an embodiment of the present invention, the submerged leaching step is performed in a batch stirred tank. As with all stirred tank processes, the ability to expose the surface area of ​​the regenerated polymer to the leaching solvent is crucial. The reactor design should include vigorous mechanical agitation and the potential use of extensive baffles.

[0167] For the submerged leaching step of the present invention, it may be beneficial to select the leaching solvent and the operating temperature and pressure so that the leaching solvent is at its boiling point during extraction. Such a design allows for continuous reflux of the solvent, which can achieve localized high concentration gradients as the refluxed solvent contacts the regenerated polymer.

[0168] In an embodiment of the present invention, the submerged leaching step is operated at a temperature below the initial melting point of the recycled polymer and at a pressure of about atmospheric pressure and about 1,000 atm. In an embodiment of the present invention, the submerged leaching step is operated at a temperature below the initial melting point of the recycled polymer and at a pressure of about atmospheric pressure. In an embodiment of the present invention, the submerged leaching step is operated at a temperature below the initial melting point of the recycled polymer and at a pressure of about atmospheric pressure and about 1,000 atm, using a leaching solvent in a plurality of leaching stages within the total residence time of the submerged leaching step and the residence time of each of the leaching stages.

[0169] In embodiments of the present invention, the leaching solvent is at or near its normal boiling point. For polyolefin recycled polymers, preferred leaching solvents for submerged leaching have boiling points ranging from 20°C to 90°C. Non-limiting examples of such solvents include tetrahydrofuran (THF), diethyl ether, hexane, acetone, ethanol, methanol, propanol, isopropanol, methyl ethyl ketone (MEK), and ethyl acetate. In embodiments of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C. In embodiments of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C, and the leaching temperature is at or near its boiling point. In embodiments of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C, the leaching temperature is at or near its boiling point, and the leaching pressure is approximately atmospheric pressure. For such leaching solvents, the pressure may also be above atmospheric pressure. In embodiments of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C, and the leaching pressure is between above atmospheric pressure and approximately 1,000 atm. The leaching solvent may also have a boiling point higher than the leaching temperature. In an embodiment of the present invention, the leaching solvent has a normal boiling point higher than the leaching temperature. In an embodiment of the present invention, the leaching solvent is ethyl acetate; the leaching temperature is between about 20°C and about 120°C; and the leaching pressure is between about atmospheric pressure and about 1,000 atm. In an embodiment of the present invention, the leaching temperature is between about 20°C and about 90°C, and the leaching pressure is between about atmospheric pressure and about 1,000 atm, the leaching solvent is ethyl acetate, the total residence time of the leaching step is less than about 360 minutes, and the average removal efficiency is about 55%. In an embodiment of the present invention, the leaching solvent is hexane; the leaching temperature is between about 20°C and about 120°C; and the leaching pressure is between about atmospheric pressure and about 1,000 atm.

[0170] Due to the increased submersion leaching pressure, a leaching solvent having a normal boiling point below the leaching temperature is also preferred. In an embodiment of the present invention, the leaching solvent has a normal boiling point below the leaching temperature. In an embodiment of the present invention, the leaching solvent is propane. In an embodiment of the present invention, the leaching solvent is propane; the leaching temperature is between about 20°C and about 120°C; and the leaching pressure is between about 9 atm and about 1,000 atm. In an embodiment of the present invention, the leaching solvent is dimethyl ether (DME). In an embodiment of the present invention, the leaching solvent is DME; the leaching temperature is between about 20°C and about 120°C; and the leaching pressure is between about 6 atm and about 1,000 atm.

[0171] Leaching solvents having a normal boiling point lower than the leaching temperature and a critical temperature lower than the leaching temperature are also preferred. In an embodiment of the present invention, the leaching solvent has a normal boiling point lower than the leaching temperature and its critical temperature is lower than the leaching temperature. In an embodiment of the present invention, the leaching solvent is ethane. In an embodiment of the present invention, the leaching solvent is critical or supercritical ethane. In an embodiment of the present invention, the leaching solvent is ethane; the leaching temperature is between about 31°C and about 120°C; and the leaching pressure is between about 40atm and about 1,000atm. In an embodiment of the present invention, the leaching solvent is CO2. In an embodiment of the present invention, the leaching solvent is CO2, the leaching temperature is between about 31°C and about 120°C; and the leaching pressure is between about 68atm and about 1,000atm. In an embodiment of the present invention, the leaching solvent is CO2 with less than 5% by weight water.

[0172] The density of the leaching solvent is preferably less than the density of the recycled polymer at the temperature and pressure of the submerged leaching step. For recycled polyethylene, the density of the leaching solvent at the temperature and pressure of the submerged leaching step is preferably less than about 0.90 g / mL, although higher densities can be used.

[0173] Preferred leaching solvents include solvents that have a higher affinity for chemical contaminants than for regenerated polymers. Relative to their affinity for polyolefins, solvents that have a high affinity for the chemical contaminants of concern in the regenerated polyolefins include, but are not limited to, diethyl ether, MEK, ethyl acetate, THF, acetone, methylene chloride, and methanol. Other oxygenated and polar hydrocarbon solvents may have similar required affinities. Solvents lacking these characteristics may still be used, but a higher solvent to polymer ratio may be required. Preferably, the solvent should not significantly dissolve the regenerated polymer (less than about 5% by weight soluble) at the temperature and pressure of the immersion leaching step.

[0174] In an embodiment of the present invention, the leaching solvent is an organic solvent or a mixture of organic solvents. In an embodiment of the present invention, the leaching solvent is selected from the group comprising hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group comprising aliphatic hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group comprising aromatic hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group comprising alkanes. In an embodiment of the present invention, the leaching solvent is selected from the group comprising methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, hexane (n-hexane, isohexane, neohexane), heptane, octane or a mixture thereof. In an embodiment of the present invention, the leaching solvent is at least one of DME, diethyl ether, MEK, ethyl acetate, THF, acetone, methanol and CO2 or a mixture thereof.

[0175] The temperature may vary during the course of the submerged leaching step but is generally consistent within a given stage of the unit operation. The pressure may be varied to alter the solubility of the leaching solvent in the recycled polymer or to increase the solubility of chemical contaminants in the leaching solvent.

[0176] The submerged leaching process can be carried out in stages and combined with other types of additional leaching steps not discussed in this disclosure. The same is true for liquid-liquid extraction methods. In addition, the liquid-liquid extraction process can be combined with submerged leaching steps at various stages to form a given purification method. In embodiments of the present invention, the number of leaching stages is more than one. In embodiments of the present invention, the number of leaching stages is between about 1 and about 50. In embodiments of the present invention, the number of leaching stages is between about 2 and about 30. In embodiments of the present invention, the number of leaching stages is between about 5 and about 20. In embodiments of the present invention, the number of liquid-liquid stages is more than one. In embodiments of the present invention, the number of leaching stages is more than one. In embodiments of the present invention, the number of liquid-liquid stages is one or more and the number of leaching stages is one or more.

[0177] A single stirred tank reactor will achieve a certain removal efficiency. Efficiency can be increased by having multiple stirred tank reactors in series, where the recycled polymer from stage 1 is primarily separated from the stage 1 leaching solvent, and this stage 1 plastic is used in stage 2 with fresh leaching solvent. This is repeated for each additional stage. This process increases removal efficiency at the expense of additional reactors and complexity, but maintains overall time, throughput, and solvent utilization. In practice, for a stirred tank system, the number of reactor stages can be anywhere from 1 to about 10. If a larger number of stages is desired, a continuous countercurrent process can be used.

[0178] While not wishing to be bound by theory, the theoretical maximum contaminant removal capacity of the submerged leaching step is based on the thermodynamic equilibrium / partitioning of the chemical contaminants between the regenerated polymer and the leaching solvent at the temperature and pressure of the submerged leaching step. Due to kinetic limitations in the submerged leaching step, thermodynamic equilibrium may not be achieved. This is true for the overall submerged leaching step and for each submerged leaching stage as well. A higher leaching solvent to regenerated polymer mass ratio will drive thermodynamics and kinetics in favor of leaching at the expense of greater leaching solvent consumption and a larger leaching process size, which equates to greater cost. Therefore, a balance must be found between these important design and operating variables for the removal efficiency of a selected chemical contaminant.

[0179] In general, applicants have found that the mass ratio of total fresh or renewed leaching solvent to recycled polymer is preferably greater than about 5: 1. In embodiments of the present invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 10: 1. In embodiments of the present invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 15: 1. In embodiments of the present invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 20: 1. In embodiments of the present invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 30: 1 and less than about 100: 1.

[0180] If submerged leaching is accomplished in stepwise or continuous stages, the ratio of leaching solvent to recycled polymer for each stage can be lower than this specified range (but still above the minimum of approximately 5:1 per stage), but the total solvent used in the total recycled polymer, represented by the sum of the solvents used in all stages, should be within this range. Furthermore, contaminated solvent from any stage can be used "as is" as solvent in another stage. Contaminated solvent at any point in the process can be renewed by known methods such as distillation, filtration, ion exchange, or a combination thereof.

[0181] Another important kinetic driver is the average surface area to volume ratio of the regenerated polymer within and exposed to the leaching solvent. Generally, the time required to extract chemical contaminants from the regenerated polymer is a strong function of the diffusion path length within the regenerated polymer. The diffusion path length is indirectly proportional to the average surface area to volume ratio of the regenerated polymer's geometry and the accessibility of the surface area to the leaching solvent. Therefore, a higher average surface area to volume ratio will result in a reduced diffusion path length and faster diffusion kinetics. For immersion leaching steps, a high average surface area to volume ratio is a key parameter for rapid and efficient removal of both surface and bulk contaminants.

[0182] For the immersion leaching step, since the processing temperature is below the initial melting point, the average surface area to volume ratio of the regenerated polymer within and exposed to the extraction solvent is essentially the same as the average surface area to volume ratio of the regenerated polymer. For membrane-based regenerated polymers, the immersion leaching step is ideal because of the extremely high inherent average surface area to volume ratio. If the regenerated polymer is provided in other forms with lower average surface area to volume ratios, such as pellets, granular bottles, granular parts, etc., it would be advantageous to increase the surface area to volume ratio by various means. These means include, but are not limited to, mechanical grinding, cryogenic grinding, calendaring, pressing, stretching, etc.

[0183] A known method of increasing the effective mass transfer at the regenerated polymer-leaching solvent interface with a given surface area to volume ratio and a given set of conditions is by applying energy to the regenerated polymer, such as but not limited to ultrasonic energy and / or vibrations in the form of microwaves.

[0184] After the submerged leaching step, the leached polymer can be devolatilized to remove the leaching solvent. The contaminated leaching solvent will contain a small amount of dissolved regenerated polymer, leached contaminants, and pure leaching solvent. There are many methods for recovering purer polymer and leaching solvent that are independent of leached contaminants.

[0185] Typically, regardless of the process type or leaching solvent, small amounts of regenerated polymer can dissolve in the leaching solvent. In particular, low MW waxes are particularly susceptible to dissolution in the leaching solvent. Due to the deposition of wax on processing equipment, these can become problems in the distillation-based recovery of purified leaching solvents. Methods are known to reduce this tendency. One such method is to lower the temperature of the contaminated leaching solvent to below the cloud point to precipitate the polymer or wax phase and then filter it. Unlike regenerated polymers, the residual plastic or wax produced by the precipitation of the contaminated solvent may contain significant contamination.

[0186] Distillation of contaminated leaching solvent can be used to regenerate leaching solvent for reuse in various leaching operations. However, considering the high leaching solvent volumes used in the present invention, distillation may not be economically viable. In addition, because the concentrations of the chemical contaminants of interest in the present invention are extremely low, the concentrations of these chemical contaminants in the contaminated leaching solvent can be correspondingly low or even lower. Therefore, a preferred method for purifying the contaminated leaching solvent is by directly removing the contaminants without volatilizing the entire leaching solvent phase. Such methods include ion exchange, adsorption / absorption methods, etc. Examples include passing the contaminated leaching solvent through activated carbon, alumina, or an activated alumina bed. This method can be used alone or in combination with distillation to achieve the correct level of purification at the correct energy consumption. In addition, the contaminated leaching solvent from any leaching stage can be used "as is" as the leaching solvent for another stage. The contaminated leaching solvent at any point in the process can be renewed by known methods or combinations such as distillation, filtration, ion exchange, etc.

[0187] The leached polymer may contain a small amount of leaching solvent in the form of physical adsorption or bulk adsorption. The concentration of the leaching solvent in the leached polymer can be reduced by devolatilization techniques. In an embodiment of the present invention, the leached polymer is devolatilized to a content of less than 1% by weight of the leaching solvent in the regenerated polymer.

[0188] Stirred tank reactors operated at the boiling point of the leaching solvent provide improvements over existing methods. For example (Examples 1, 2, 3, and 4 and Tables 7, 8, 9, and 10), submerged leaching steps with ethyl acetate or THF provide greater than about 88% removal efficiency of selected contaminants.

[0189] In an embodiment of the present invention, the leaching solvent is ethyl acetate. In an embodiment of the present invention, the leaching solvent is ethyl acetate, and the leaching pressure is about atmospheric pressure. In an embodiment of the present invention (Example 1 and Table 7), the submerged leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is about atmospheric pressure, and the leaching solvent includes ethyl acetate. In an embodiment of the present invention, the submerged leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is about atmospheric pressure, and the leaching solvent includes ethyl acetate; wherein the recycled polymer has a particle size of about 80 mm -1 the surface area to volume ratio of the polymer is 0.0447 W / m; the number of leaching stages is 2, the mass ratio of ethyl acetate to recycled polymer in each stage is about 18:1, the immersion leaching residence time in each stage is about 50 minutes, the mass ratio of total ethyl acetate to recycled polymer is about 36:1, and the total residence time is about 100 minutes; and the average value of the concentration reduction of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and di-2-ethylhexyl phthalate is about 89%.

[0190] In an embodiment of the present invention (Example 2 and Table 8), the submerged leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is about atmospheric pressure, and the leaching solvent comprises ethyl acetate; wherein the regenerated polymer has a thickness of about 80 mm. -1 the surface area to volume ratio of the leaching agent is about 2; the number of leaching stages is 2, the mass ratio of ethyl acetate to recycled polymer in each stage is about 18:1, the immersion leaching residence time in each stage is about 30 minutes, the mass ratio of total ethyl acetate to recycled polymer is about 36:1, and the total residence time is about 60 minutes; and the average value of the concentration reduction of 4-tert-amylphenol, bisphenol A, OCDD, PCB118 and di-2-ethylhexyl phthalate is about 89%.

[0191] In an embodiment of the present invention, the leaching solvent is THF. In an embodiment of the present invention, the leaching solvent is THF, and the leaching pressure is about atmospheric pressure. In an embodiment of the present invention, the submerged leaching is carried out in a stirred tank, the leaching temperature is about 66°C, the leaching pressure is about atmospheric pressure, and the leaching solvent comprises THF. In an embodiment of the present invention (Example 3 and Table 9), the submerged leaching step is carried out in a stirred tank, the number of leaching stages is 2, the leaching temperature is about 66°C, the leaching pressure is about atmospheric pressure, the leaching solvent comprises THF, and the regenerated polymer has a particle size of about 80 mm. -1 the surface area to volume ratio of the leaching agent, the THF to recycled polymer ratio was about 18:1 in each stage, the residence time in each leaching stage was about 50 minutes, the total THF to recycled polymer mass ratio was about 36:1, the total residence time for the submerged leaching step was about 100 minutes; and the average value of the reduction in the concentration of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate was about 90%.

[0192] In an embodiment of the present invention, the leaching solvent is DME, the leaching temperature is about 70°C, and the leaching pressure is greater than about 18 atm. In an embodiment of the present invention, the leaching solvent is DME, the recycled polymer has a viscosity of about 80 mm. -1 The surface area to volume ratio of the leaching solvent is about 70°C, the leaching temperature is about 70°C, and the leaching pressure is greater than about 18 atm. In an embodiment of the present invention, the leaching solvent is CO2, the leaching temperature is about 70°C, the leaching pressure is about 340 atm, and the recycled polymer has a surface area to volume ratio of about 80 mm -1 surface area to volume ratio.

[0193] After the submerged leaching step, the leached polymer may be physically wetted by the residual leaching solvent and may contain a small amount of absorbed leaching solvent. As discussed above, there are many methods for recovering the leached polymer and leaching solvent that are unrelated to the leaching contaminants. The leached polymer can be dried and devolatilized by many known commercial means. One method is by cyclone drying. Another method is by melt extrusion with a devolatilization stage. In an embodiment of the present invention, the leached polymer is processed to reduce the leaching solvent in the regenerated polymer to less than about 1 weight %. The contaminated leaching solvent can be cleaned with known distillation methods, ion exchange, filtration, etc. The devolatilized regenerated polymer obtained can be used as is or can be further processed into other forms, including pellets, by various methods.

[0194] In an embodiment of the present invention, the total residence time of the leaching step is less than about 600 minutes. In an embodiment of the present invention, the total residence time of the leaching step is less than about 480 minutes. In an embodiment of the present invention, the total residence time of the leaching step is less than about 360 minutes. In an embodiment of the present invention, the total residence time of the leaching step is less than about 180 minutes. In an embodiment of the present invention, the total residence time of the leaching step is less than about 60 minutes.

[0195] In an embodiment of the present invention, the residence time of each of the leaching steps is less than about 180 minutes. In an embodiment of the present invention, the residence time of each of the leaching steps is less than about 90 minutes. In an embodiment of the present invention, the residence time of each of the leaching steps is less than about 60 minutes. In an embodiment of the present invention, the residence time of each of the leaching steps is less than about 30 minutes. In an embodiment of the present invention, the residence time of each of the leaching steps is about 20 minutes.

[0196] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants comprise at least one of an alkylphenol, a bisphenol, a dioxin, a PCB, and a phthalate; and b) leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a leached polymer comprising at least one of the alkylphenol, bisphenol, dioxin, PCB, or phthalate, each having a concentration; and wherein the average removal efficiency is greater than about 55%.

[0197] In an embodiment of the invention, wherein the leaching step is performed in a continuous stirred tank reactor (CSTR); wherein the regenerated polymer is surface washed in a non-densified state in a surface washing process prior to dissolution; wherein the surface washing process results in a reduction of loosely bound surface contamination by greater than about 80%; wherein the regenerated polymer has a surface area greater than about 1 mm prior to surface washing. -1wherein the surface washing process is of the deinking type; wherein the deinking process results in a ΔE change of less than about 10% between the deinked polymer and the regenerated polymer without surface printing ink; wherein the leaching solvent is ethyl acetate; wherein the CSTR comprises 3 leaching stages; wherein the leaching temperature is about 77°C and the leaching pressure is close to atmospheric pressure; wherein the residence time of each of the leaching stages is about 20 minutes; wherein the regenerated polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets; and wherein the average removal efficiency is greater than about 55%.

[0198] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a concentration; and wherein the recycled polymer contaminants comprise at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; and b) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a recycled polymer comprising 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. Leached polymers of at least one of 118 and 2-ethylhexyl phthalate, the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate each having a concentration; wherein the average removal efficiency is greater than about 55%.

[0199] VII. Combination of surface purification and immersion leaching steps

[0200] Typically, the combination of a surface purification step and an immersion leaching step provides a synergistic benefit in the overall removal of contamination. The surface purification step will effectively remove both impermeable and permeable surface contamination, including chemical contaminants and chemical contaminant precursors. Thus, surface purification reduces the burden on the immersion leaching step and makes it more effective. If the recycled polymer is heavily contaminated with surface contaminants, such contamination is preferably removed first in a surface purification step and then by an immersion leaching step. Once the surface contaminants are removed in the surface purification step, the remaining overall permeable contamination will be removed by the immersion leaching step. The only contamination that is not significantly removed by this two-step process is overall impermeable contamination, such as heavy metals that were intentionally added during the production of the original plastic part.

[0201] Preferred methods for surface washing have been discussed in the surface purification section. An even more preferred surface washing method is the deinking method also described in the surface purification method (Comparative Example 3). This method not only removes surface contaminants such as dirt, but also removes surface-printed ink. This method is also quite effective in removing paper labels, which are precursors to chemical contaminants. In this method, recycled polymer with exposed original surface area is fed into a multi-step aqueous washing process, where surface contaminants including surface-printed ink, dirt, grit, paper, adhesives, etc. are removed. The resulting material is then dried. The dried material can be further densified into pellets using extrusion including devolatilization and melt filtration. For the purposes of this invention, a deinking method is any surface washing method that removes sufficient surface imprint to produce a ΔE difference of less than about 10% between the deinked recycled polymer and the unprinted recycled polymer (ΔE measured using Method 3 in Section IX).

[0202] For nomenclature purposes, the regenerated polymer is fed to the surface purification process, and the resulting surface-purified polymer will be referred to as surface-washed polymer. The surface-washed polymer is then fed to the immersion leaching step, and the resulting polymer is referred to as leached polymer. The surface purification process can involve multiple surface purification processes. The immersion leaching process can involve multiple immersion leaching steps of various types. The removal efficiency of the combined surface purification and immersion leaching steps will be calculated from the regenerated polymer concentration and the associated leached polymer. The combination of surface washing and immersion leaching steps provided an average reduction of approximately 95% in the concentrations of bisphenol A, 4-tert-amylphenol, OCDD, PCB 108, and di-2-ethylhexyl phthalate (Example 4 and Table 10).

[0203] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of a PCR polymer, a PIR polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each having a concentration; and wherein the recycled polymer contaminants comprise at least one of an alkylphenol, a bisphenol, a dioxin, a PCB, and a phthalate; b) surface washing the recycled polymer to produce a surface-washed polymer; and c) leaching the alkylphenol, bisphenol, dioxin, PCB, and phthalate from the surface-washed polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a leached polymer comprising at least one of the alkylphenol, bisphenol, dioxin, PCB, and phthalate, each having a concentration; and wherein the average value of the reduction in concentration is greater than about 55%.

[0204] In an embodiment of the present invention, the submerged leaching step is performed after surface washing. In an embodiment of the present invention, the submerged leaching step is performed after the surface washing process; and wherein the regenerated polymer is not densified prior to the surface washing process. In an embodiment of the present invention, the submerged leaching step is performed after the surface washing process; wherein the regenerated polymer is not densified prior to the surface washing process; and wherein the surface washed regenerated polymer may be densified prior to the submerged leaching step.

[0205] In an embodiment of the invention, the submerged leaching step uses a leaching solvent at a temperature and pressure; wherein the submerged leaching step is operated in multiple stages; and wherein the regenerated polymer has been partially purified using a surface washing process.

[0206] In an embodiment of the present invention (Example 4 and Table 10), the surface washing process involved deinking commercially available from Cadel; the deinking resulted in a ΔE change of less than about 10% and removal of more than about 80% of loosely bound surface contaminants; the immersion leaching step was operated in a stirred tank; the leaching temperature was about 77.1°C; the leaching pressure was about atmospheric pressure; the leaching solvent included ethyl acetate; and the total residence time was about 60 minutes. In an embodiment of the present invention, the surface washing process involved deinking commercially available from Cadel; the deinking resulted in a ΔE change of less than about 10% and removal of more than about 80% of loosely bound surface contaminants; the immersion leaching step was operated in a stirred tank and involved two stages; the leaching temperature was about 77.1°C; the leaching pressure was about atmospheric pressure; the leaching solvent included ethyl acetate; the residence time for each stage was about 30 minutes; and the concentration of OCDD was reduced by about 98%.

[0207] In an embodiment of the present invention, the surface washing process comprises any known surface washing method; the submerged leaching step uses a stirred tank; and the submerged leaching step uses a leaching solvent. In an embodiment of the present invention, the submerged leaching step uses a stirred tank and includes multiple leaching stages.

[0208] In an embodiment of the invention, wherein prior to the leaching step, the regenerated polymer is surface washed in a non-densified state in a surface washing step to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination by greater than about 80%; wherein the regenerated polymer has a thickness greater than about 1 mm prior to surface washing. -1 wherein the surface washing process is of the deinking type; wherein the deinking process results in a ΔE change of less than about 10% between the deinked polymer and the regenerated polymer without surface printing ink; wherein the leaching step is carried out in a continuous stirred tank reactor (CSTR); wherein the leaching solvent is ethyl acetate; wherein the CSTR comprises 3 leaching stages; wherein the leaching temperature is about 77°C and the leaching pressure is close to atmospheric pressure; wherein the residence time of each of the leaching stages is about 20 minutes; wherein the average removal efficiency is greater than about 55%; and wherein the leached polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets.

[0209] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants comprise at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; and c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a recycled polymer comprising 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. Leached polymers of at least one of 118 and 2-ethylhexyl phthalate, the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate each having a concentration; wherein the average removal efficiency is greater than about 55%.

[0210] VIII. Purification of leached polymers

[0211] Surprisingly, it has been found that leached polymer in high MW polymer solutions can be purified by filtration. Figure 1A and Figure 1B The process, as exemplified in FIG, comprises: 1) dissolving the leached polymer in a fluid solvent at a dissolution temperature and a dissolution pressure to produce a first solution ( Figure 1A Steps c and Figure 1B 2) settling the first solution at a temperature and a pressure to produce a second solution comprising a settling polymer ( Figure 1A Steps d and Figure 1B 3) filtering the second solution by mechanical filtration at a certain temperature and a certain pressure to produce a third solution comprising a filtered polymer, and filtering the third solution by adsorption filtration at a certain temperature and a certain pressure to produce a fourth solution comprising twice filtered polymer ( Figure 1A Steps e and f in Figure 1B and 4) separating the secondary filtered polymer from the fourth solution to produce a purer polymer ( Figure 1A Steps g and Figure 1BIt should be noted that the above-mentioned temperature and pressure values ​​may vary from one step to another. Figure 3 A schematic diagram of the experimental setup used in the dissolution, sedimentation, filtration and separation steps is shown in FIG.

[0212] In embodiments of the present invention, the purer polymer that can be derived from the PCR stream is substantially free of contaminants, free of pigments, free of odors, is homogeneous, and has properties similar to the virgin polymer.

[0213] Fluid solvent

[0214] In embodiments of the present invention, the fluid solvent has a normal boiling point of less than about 70°C. In embodiments of the present invention, the fluid solvent has a normal boiling point of less than about 70°C and greater than about -45°C. In embodiments of the present invention, the fluid solvent has a normal boiling point of less than about 70°C and greater than about -45°C and a normal enthalpy of vaporization of less than about +25 kJ / mol. Pressurization is performed to place the solvent having a normal boiling point below the operating temperature range of the present invention in a state with little or no solvent vapor.

[0215] In an embodiment of the present invention, the fluid solvent is selected from olefins, aliphatic hydrocarbons, and mixtures thereof. In an embodiment of the present invention, the aliphatic hydrocarbons of the fluid solvent are selected from C1-C6 aliphatic hydrocarbons and mixtures thereof. In an embodiment of the present invention, the fluid solvent comprises n-butane, butane isomers, or mixtures thereof.

[0216] In an embodiment of the present invention, the fluid solvent having a normal boiling point of less than about 70° C. is selected from the group consisting of carbon dioxide, ketones, alcohols, ethers, esters, olefins, alkanes, and mixtures thereof. Non-limiting examples of fluid solvents having a normal boiling point below about 70° C. are carbon dioxide, acetone, methanol, dimethyl ether, diethyl ether, ethyl methyl ether, tetrahydrofuran, methyl acetate, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, branched isomers of pentene, 1-hexene, 2-hexene, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isomers of isohexane, and others that may be apparent to one of ordinary skill in the art.

[0217] The selection of an appropriate fluid solvent or solvent mixture will depend on which polymer or polymer mixture is being purified according to the present invention. In addition, the polymer being purified and the corresponding fluid solvent used will determine the temperature and pressure ranges used to perform the steps of the present invention. The following reference provides an overview of the phase characteristics of polymers in fluid solvents of the type described in the present invention: McHugh et al. (1999) Chem.Rev . 99:565-602.

[0218] Dissolve

[0219] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises dissolving the leached polymer in a fluid solvent at a certain temperature and a certain pressure, wherein the polymer is dissolved in the fluid solvent. Although not wishing to be bound by any theory, the applicant believes that the temperature and pressure can be controlled in a manner that thermodynamically favors the dissolution of the regenerated polymer in the fluid solvent. In addition, the temperature and pressure can be controlled in a manner that enables the dissolution of a specific polymer or polymer mixture without dissolving other polymers or polymer mixtures. This controlled dissolution can separate the polymer from the polymer mixture.

[0220] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polymer in a fluid solvent that does not dissolve contaminants under uniform temperature and pressure conditions. The contaminants may include pigments, fillers, dirt, and other polymers. These contaminants are released from the leached polymer upon dissolution and are then removed from the polymer solution through a subsequent solid-liquid separation step.

[0221] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in a fluid solvent at a temperature and a pressure, wherein the polyethylene is dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polymer in a fluid solvent at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polymer in a fluid solvent at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polymer in a fluid solvent at a pressure of about 200psig (1.38MPa) to about 9,000psig (62.05MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polymer in a fluid solvent at a pressure of about 400psig (2.76MPa) to about 2,600psig (17.93MPa).

[0222] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-butane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-butane at a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-butane at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-butane at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0223] In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polyethylene in n-butane at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polyethylene in n-butane at a mass percent concentration of up to 20%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 12%.

[0224] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in propane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in propane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in propane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-pentane at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-pentane at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polyethylene in n-pentane at a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0225] In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polyethylene in n-pentane at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polyethylene in n-pentane at a mass percent concentration of up to 20%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 12%.

[0226] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in a fluid solvent at a temperature and a pressure, wherein the polypropylene is dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in n-butane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in n-butane at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in n-butane at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in n-butane at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0227] In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polypropylene in n-butane at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polypropylene in n-butane at a mass percent concentration of up to 20%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 12%.

[0228] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in propane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in propane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in propane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in propane at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polypropylene in propane at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a method for purifying leached polymer comprises dissolving leached polypropylene in propane at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0229] In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polypropylene in propane at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the leached polymer comprises dissolving the leached polypropylene in propane at a mass percent concentration of up to 20%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 12%.

[0230] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in a fluid solvent at a temperature and a pressure, wherein the leached polystyrene dissolves in the fluid solvent. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in n-butane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in n-butane at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in n-butane at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached polystyrene in n-butane at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0231] In an embodiment of the present invention, the method for purifying leached polystyrene comprises dissolving the leached polystyrene in n-butane at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying leached polystyrene comprises dissolving the leached polystyrene in n-butane at a mass percent concentration of up to 20%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 12%.

[0232] In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in a fluid solvent at a temperature and a pressure, wherein the leached poly(dimethylsiloxane) is dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0233] In an embodiment of the present invention, a method for purifying leached poly(dimethylsiloxane) comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying leached poly(dimethylsiloxane) comprises dissolving the leached poly(dimethylsiloxane) in n-butane at a mass percent concentration of up to 20%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0234] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises dissolving a leached polymer in a solvent selected from a first fluid solvent, a second fluid solvent, and mixtures thereof at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant.

[0235] In an embodiment of the present invention, the leached polymer is dissolved in a fluid solvent or fluid solvent mixture at a concentration of at least 0.5% by weight. In an embodiment of the present invention, the temperature during the dissolving step is from about 110° C. to about 220° C. In an embodiment of the present invention, the pressure during the dissolving step is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0236] settlement

[0237] In embodiments of the present invention, the method for purifying polymer is included in and separates undissolved pollutant from polymer solution via sedimentation step at certain temperature and pressure, and wherein polymer keeps being dissolved in the fluid solvent.In embodiments of the present invention, sedimentation step causes undissolved pollutant to stand the force of uniformly moving undissolved pollutant along the direction of force.Usually the sedimentation force applied is gravity, but can also be centrifugal force, centripetal force or some other force.The amount of applied force and sedimentation duration will depend on some parameters, include but not limited to: the particle size of pollutant particles, the density of pollutant particles, the density of fluid or solution and the viscosity of fluid or solution.The following equation is the relationship between above-mentioned parameters and sedimentation velocity, and this sedimentation velocity is the measurement of pollutant sedimentation rate: ,in is the sedimentation velocity, is the density of the pollutant particles, is the density of the fluid or solution, is the acceleration due to the applied force (usually gravity), is the radius of the pollutant particle, and is the dynamic viscosity of a fluid or solution. Some of the key parameters that determine the viscosity of a solution are: the chemical composition of the fluid solvent, the MW of the polymer dissolved in the fluid solvent, the concentration of the polymer dissolved in the fluid solvent, the temperature of the fluid solvent solution, and the pressure of the fluid solvent solution.

[0238] In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a temperature and pressure, wherein the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a pressure of about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0239] In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution at a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a process for purifying recycled polymer comprises settling contaminants from a polyethylene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0240] In an embodiment of the present invention, the method for purifying recycled polymers comprises settling contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying recycled polymers comprises settling contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0241] In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-pentane solution at a pressure of about 800 psig (5.52 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-pentane solution at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises settling contaminants from a polyethylene / n-pentane solution at a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0242] In an embodiment of the present invention, the method for purifying recycled polymers comprises settling contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying recycled polymers comprises settling contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0243] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / fluid solvent solution at a temperature and pressure, wherein the polypropylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises settling contaminants from a polypropylene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises settling contaminants from a polypropylene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0244] In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polypropylene / n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polypropylene / n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0245] In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a process for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0246] In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying recycled polymer comprises settling contaminants from a polypropylene / propane solution, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0247] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / fluid solvent solution at a temperature and pressure, wherein the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polystyrene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polystyrene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0248] In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polystyrene / n-butane solution, wherein the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polystyrene / n-butane solution, wherein the polystyrene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 12%.

[0249] In embodiments of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure, wherein the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In embodiments of the present invention, the method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In embodiments of the present invention, the method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In embodiments of the present invention, the method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In embodiments of the present invention, the method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution and a solid medium at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0250] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 16% by mass. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 14% by mass. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 12% by mass.

[0251] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling a first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising the settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant.

[0252] In embodiments of the invention, the temperature in the settling step is from about 110° C. to about 220° C. In embodiments of the invention, the pressure in the settling step is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0253] Mechanical filtration

[0254] For the purposes of this disclosure, and unless otherwise specified, the term "filtration" refers to either "mechanical filtration" or "adsorption filtration," or both types of filtration. A typical filtration system includes a filter medium, a filter container, a filter inlet, and a filter outlet. The filter medium comprises filter particles contained within the filter container. The filter inlet is in fluid communication with the filter container and conveys a filtered feed stream into the filter container, while the filter outlet is in fluid communication with the filtration system and conveys a filtrate stream out of the filter container. The filtration system may include one or more filter media, filter containers, and filter inlets and filter outlets connected in series or in parallel. Furthermore, the filtration system may operate with radial or axial flow, or with upward, downward, or cross-flow. A non-limiting example of a radial flow filter is a candle filter. Furthermore, filtration may be depth filtration or surface filtration, and may be based on a mechanical mode of action. A non-limiting example of a mechanical mode of action is size exclusion, in which suspended (dispersed) contaminants are retained by the filter medium and, therefore, separated from the filtered feed stream, because their size is larger than the pores of the filter medium. As described above, size exclusion is an interparticle phenomenon.

[0255] Filter media used in depth filtration include aggregates of filter particles, which may be homogeneous or heterogeneous. The filter particles may be distributed uniformly or non-uniformly (e.g., as layers of different filter particles) within the filter medium. The filter particles forming the filter medium need not be of the same shape or size and may be provided in a loose or interconnected form. For example, the filter medium may include filter particles that are loosely associated or partially or completely bonded to form a unitary structure via a polymeric binder or other means.

[0256] In addition, filter particles can be provided in a variety of shapes and sizes. For example, but not limited to, filter particles can be provided in simple forms, such as powders, particles, fibers and beads. Filter particles can be provided in the shape of spheres, polyhedrons, cylinders and other symmetrical, asymmetrical and irregular shapes. In addition, filter particles can also be formed into complex forms, such as nets, screens, grids, nonwoven materials, woven materials and adhesive blocks, which may or may not be formed by the above-mentioned simple forms. Filter particles can vary in size, from intangible filter particles (e.g., very fine powders) to tangible filter particles. In addition, in the filter particles used in any single filter system, the size of the filter particles does not have to be uniform. In fact, it may be desirable to provide filter particles with different sizes in a single filter.

[0257] In an embodiment of the present invention, the size of the filter particles varies between about 0.1 mm and about 10 mm. In an embodiment of the present invention, the size of the filter particles varies between about 10 mm and about 8 mm. In an embodiment of the present invention, the size of the filter particles varies between about 100 mm and about 5 mm. In an embodiment of the present invention, the size of the filter particles varies between about 1 mm and about 4 mm. In an embodiment of the present invention, the size of the filter particles varies between about 10 µm and about 100 µm. For spherical and cylindrical particles (e.g., fibers, beads, etc.), the above dimensions refer to the diameter of the filter particles. For filter particles with significantly different shapes, the above dimensions refer to the largest dimension (e.g., length, width, or height).

[0258] Non-limiting examples of filter particles include silicon oxide (silicon dioxide), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, amorphous volcanic glass, regenerated glass, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, fuller's earth, bentonite, metal organic framework (MOF), covalent organic framework (COF), zeolitic imidazolate framework (ZIF), cellulose, lignocellulose, anthracite, carbon black, coke, and activated carbon. In embodiments of the present invention, the filter particles are selected from silicon dioxide, activated alumina, silica gel, volcanic glass, fuller's earth, bentonite, and mixtures thereof. In embodiments of the present invention, the filter particles are selected from activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In embodiments of the present invention, the filter particles are selected from MOF, COF, ZIF, activated carbon, activated alumina, and mixtures thereof. In embodiments of the present invention, the filter particles are selected from diatomaceous earth, activated alumina, and mixtures thereof.

[0259] Non-limiting examples of filter media used in surface filtration are thin layers of filter particles, porous ceramics, filter paper, filter cloth, plastic film, screen, nonwoven material, woven material, porous glass frit / sintered metal and perforated plate. In typical surface filtration, the retained pollutants form a filter cake on top of the filter medium, and the thickness of the filter cake increases as the filtration proceeds. Typically, after a certain filtration time, the filter cake needs to be removed because the filter cake provides an unsustainable pressure drop through mechanical action or backwashing. In an embodiment of the present invention, the filter medium used in surface filtration is selected from a thin layer of diatomaceous earth particles deposited on a woven metal porous core (commonly referred to as a sock). The porous core supports the filter medium and allows the filtered feed stream to flow through. Non-limiting examples of the core are perforated tubes and screen sleeves.

[0260] Filter aids may be used during filtration. Non-limiting examples of filter aids include diatomaceous earth (also known as kieselguhr), cellulose, and perlite. These filter aids can be used as a precoat on the filter media or added to the filter feed stream. In the latter case (also known as bulk feed), the filter aid increases the porosity of the filter cake formed on the filter media, thereby reducing the pressure drop across the filter cake during filtration.

[0261] At the end of its useful life, the filter can be removed from operation and replaced with a new filter, or regenerated. Non-limiting examples of regeneration are backflushing, thermal regeneration, and solvent regeneration.

[0262] In an embodiment of the present invention, the surface filter comprises a candle filter. In an embodiment of the present invention, the candle filter comprises a thin layer of diatomaceous earth deposited onto a woven metal porous core. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is between about 1 mm and about 20 mm. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is between about 2 mm and about 10 mm. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is between about 3 mm and about 5 mm.

[0263] The permeability of a filter medium is measured (as is well known to those skilled in the art) by passing a fluid through the filter medium and measuring the flow rate and pressure drop. The unit of measurement is millidarcy (mD), and 1 mD is equivalent to 1 mL of fluid with a viscosity of 1 mPa.s (1 cP) flowing through a cross-sectional area of ​​1 cm in 1 second at a pressure of 1 atm. 2 and a filter medium thickness of 1 cm. In embodiments of the present invention, the diatomaceous earth medium has a permeability between about 30 mD and about 20,000 mD. In embodiments of the present invention, the diatomaceous earth medium has a permeability between about 400 mD and about 8,000 mD. In embodiments of the present invention, the diatomaceous earth medium has a permeability between about 1,000 mD and about 4,000 mD. In embodiments of the present invention, the diatomaceous earth medium has a permeability between about 2,300 mD and about 3,400 mD.

[0264] In embodiments of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 0.3 µm. In embodiments of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 0.8 µm. In embodiments of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 1 µm. In embodiments of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 1.7 µm. In embodiments of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 4 µm.

[0265] In an embodiment of the present invention, a candle filter comprises a thin diatomaceous earth media deposited on a woven metal core; wherein the thickness of the diatomaceous earth media is between about 2 mm and about 10 mm; wherein the permeability of the diatomaceous earth media is between about 2,300 mD and 3,400 mD; and wherein the diatomaceous earth media retains suspended particles having a diameter greater than about 1.7 μm.

[0266] In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / fluid solvent solution at a temperature and a pressure, wherein the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, the method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the temperature during the filtering step is about 110°C to about 220°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / fluid solvent solution at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, the pressure during the filtering step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0267] In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0268] In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0269] In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0270] In an embodiment of the present invention, the method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0271] In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the present invention, the method for purifying regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0272] In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polypropylene / n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polypropylene / n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0273] In an embodiment of the present invention, the method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, the method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0274] In an embodiment of the present invention, a method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution, wherein polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymer comprises filtering contaminants from a polypropylene / propane solution, wherein polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 12%.

[0275] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / fluid solvent solution at a temperature and a pressure, wherein the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0276] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution, wherein polystyrene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution, wherein polystyrene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 12%.

[0277] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and a pressure, wherein the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0278] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 16% by mass. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 14% by mass. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 12% by mass.

[0279] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants comprise at least one of an alkylphenol, a bisphenol, a dioxin, a PCB, and a phthalate; b) leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a leached polymer comprising at least one of the alkylphenol, bisphenol, dioxin, PCB, or phthalate, each having a concentration; and wherein the average removal efficiency is greater than c) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; d) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising settled polymer, at least one dissolved contaminant, and less of the at least one suspended contaminant; and e) filtering the second solution by mechanical filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising filtered polymer, at least one dissolved contaminant, and even less of the at least one suspended contaminant.

[0280] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants comprise at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a recycled polymer comprising 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. 118 and 2-ethylhexyl phthalate, wherein the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate each have a certain concentration; wherein the average removal efficiency is greater than about 55%; d) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent and a mixture thereof at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising the dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant; e) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent and a mixture thereof at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising the dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant; g (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant; and f) filtering the second solution by mechanical filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtered polymer, at least one dissolved contaminant, and even less of at least one suspended contaminant.

[0281] Adsorption filtration

[0282] In an embodiment of the present invention, a method for purifying polyethylene comprises contacting a contaminated polymer solution with a solid medium at a temperature and pressure at which the polymer remains dissolved in a fluid solvent. The solid medium of the present invention (also referred to throughout the present invention as adsorption medium or adsorption filter medium) comprises solid medium particles and is any solid material that removes at least some contaminants from a solution of regenerated polyethylene dissolved in the fluid solvent of the present invention. While not wishing to be bound by any theory, the applicant believes that the solid medium removes contaminants through a variety of mechanisms. Non-limiting examples of possible mechanisms include adsorption, absorption, electrostatics, size exclusion, ion exclusion, ion exchange, and other mechanisms that may be apparent to one of ordinary skill in the art. In addition, pigments and other contaminants commonly found in regenerated polyethylene 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. Polar-polar interactions are particularly advantageous when a non-polar solvent (such as an alkane) is used as the fluid solvent.

[0283] In embodiments of the present invention, the solid medium is selected from inorganic substances, carbon-based substances, or mixtures thereof. Examples of inorganic substances include silicon oxides, aluminum oxides, iron oxides, aluminum silicates, magnesium silicates, amorphous volcanic glass, silica, silica gel, diatomaceous earth, sand, quartz, recycled glass, alumina, perlite, bleaching earth, bentonite, and mixtures thereof. Examples of carbon-based substances include anthracite, carbon black, coke, activated carbon, cellulose, and mixtures thereof. In embodiments of the present invention, the solid medium is recycled glass. In embodiments of the present invention, the solid medium particles are selected from the group consisting of solid particles of silicon oxide (silicon dioxide), silica gel, aluminum oxide (alumina), activated alumina, iron oxides, aluminum silicates, magnesium silicates, sand, quartz, diatomaceous earth, zeolites, molecular sieves, perlite, clay, bleaching earth, bentonite, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), zeolitic imidazolate frameworks (ZIFs), cellulose, and lignocellulose. In an embodiment of the present invention, the solid medium is selected from the group consisting of silica, activated alumina, silica gel, bleaching earth, bentonite, and mixtures thereof. In an embodiment of the present invention, the solid medium is selected from the group consisting of activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In an embodiment of the present invention, the solid medium is selected from the group consisting of MOFs, COFs, ZIFs, activated carbon, activated alumina, and mixtures thereof. In an embodiment of the present invention, the solid medium is selected from the group consisting of diatomaceous earth, activated alumina, and mixtures thereof.

[0284] A non-limiting example of a physical mode of action is physical adsorption (also known as physical sorption), in which dissolved contaminants are adsorbed onto the outer or inner surfaces of the pores of the filter particles due to van der Waals forces and are thereby separated from the filter feed stream. Another non-limiting example of a physical mode of action is electrostatic adsorption, in which suspended contaminants are adsorbed onto the surface of the filter particles due to electrostatic attraction. Filter particles and filter media that remove contaminants primarily by adsorption are referred to as adsorption filter particles and adsorption filter media, respectively.

[0285] The adsorption filter medium is typically contained in a cylindrical filter container as loose media or a cohesive block, and the adsorption filtration can be axial flow or radial flow. The cylindrical adsorption filter medium in the axial flow form has an aspect ratio defined as the ratio of the height of the cylindrical adsorption filter medium to the diameter. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 1. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 2. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 5. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 10. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 30. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 50. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 70.

[0286] In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 5 cm. In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 20 cm. In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 50 cm. In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 1 m. In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 1.5 m. In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 3 m. In an embodiment of the present invention, the height of the cylindrical adsorbent filter medium is equal to or greater than about 6 m.

[0287] In an embodiment of the present invention, the adsorbent filter medium is cylindrical; wherein the filter medium comprises loose adsorbent filter particles; wherein the height of the cylindrical adsorbent medium is about 122 cm; wherein the diameter of the cylindrical adsorbent medium is about 1.7 cm; wherein the adsorbent filter particles comprise activated alumina; and wherein the particle size of the adsorbent filter particles is 7×14 mesh.

[0288] In an embodiment of the present invention, the solid medium is contacted with the polymer in a container for a specified amount of time while the solid medium is agitated. In an embodiment of the present invention, the solid medium is removed from the purer polymer solution via a solid-liquid separation step. Non-limiting examples of solid-liquid separation steps include filtration, decantation, centrifugation, and sedimentation. In an embodiment of the present invention, the contaminated polymer solution is passed through a fixed bed of solid medium. In an embodiment of the present invention, the solid medium is replaced as needed to maintain the desired purity of the polymer. In an embodiment of the present invention, the solid medium is regenerated and reused in the purification step. In an embodiment of the present invention, the solid medium is regenerated during the backflush step by fluidizing the solid medium.

[0289] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / fluid solvent solution with a solid medium at a temperature and a pressure, wherein the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises contacting the polyethylene / fluid solvent solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises contacting the polyethylene / fluid solvent solution with a solid medium at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, the method for purifying a regenerated polymer comprises contacting the polyethylene / fluid solvent solution with a solid medium at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, the method for purifying a regenerated polymer comprises contacting the polyethylene / fluid solvent solution with a solid medium at a pressure of about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0290] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0291] In an embodiment of the present invention, the method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0292] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0293] In an embodiment of the present invention, the method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0294] In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a recycled polypropylene comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0295] In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / n-butane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0296] In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a recycled polypropylene comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0297] In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polypropylene / propane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0298] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / fluid solvent solution with a solid medium at a temperature and pressure, wherein the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0299] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium, wherein the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium, wherein the polystyrene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 12%.

[0300] In embodiments of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / fluid solvent solution with a solid medium at a temperature and pressure, wherein the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In embodiments of the present invention, the method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 115°C to about 280°C. In embodiments of the present invention, the method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 120°C to about 220°C. In embodiments of the present invention, the method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 140°C to about 180°C. In embodiments of the present invention, the method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0301] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 16% by mass. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 14% by mass. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a concentration of up to 12% by mass.

[0302] In an embodiment of the present invention, a method for purifying a recycled polymer is disclosed. The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer contains contaminants, each of which has a concentration; and wherein the recycled polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) leaching the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm for a total residence time. leach said alkylphenol, bisphenol, dioxin, PCB or phthalate from said recycled polymer at an average removal efficiency during the residence time of said leaching stage and each of said leaching stages to produce a leached polymer comprising at least one of alkylphenol, bisphenol, dioxin, PCB or phthalate, each having a concentration; and wherein said average removal efficiency is greater than about 55%; c) at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) MPa) to dissolve the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof to produce a first solution comprising dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; d) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising settled polymer, at least one dissolved contaminant, and less of the at least one suspended contaminant; e) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising settled polymer, at least one dissolved contaminant, and less of the at least one suspended contaminant; and e) settling the first solution at a temperature of about 90° C. to about 2 f) filtering the second solution by mechanical filtration at a temperature of about 80° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtering polymer, at least one dissolved contaminant, and even less of at least one suspended contaminant; and f) filtering the third solution by adsorptive filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising a twice filtered polymer.

[0303] In an embodiment of the present invention, a method for purifying a recycled polymer is disclosed. The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a certain concentration; and wherein the recycled polymer contaminants comprise at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a recycled polymer comprising 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. 118 and 2-ethylhexyl phthalate, each having a certain concentration of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate; wherein the average removal efficiency is greater than about 55%; d) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising the dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant; e) settling the first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a solution comprising the settled polymer, at least one f) filtering the second solution by mechanical filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtering polymer, at least one dissolved contaminant and even less of at least one suspended contaminant; and g) filtering the third solution by adsorptive filtration by contacting the third solution with one or more solid media at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising twice the filtering polymer.

[0304] In embodiments of the invention, the temperature during the dissolving, settling and filtering steps is from about 110° C. to about 220° C. In embodiments of the invention, the pressure during the dissolving, settling and filtering steps is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0305] Separation

[0306] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating a purer polymer from a fluid solvent at a temperature and pressure, wherein the polymer precipitates from solution and is no longer dissolved in the fluid solvent. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by reducing the pressure at a fixed temperature. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by reducing the temperature at a fixed pressure. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by increasing the temperature at a fixed pressure. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by reducing both the temperature and the pressure. By controlling the temperature and pressure, the solvent can be partially or completely converted from a liquid to a gas phase. In an embodiment of the present invention, by controlling the temperature and pressure of the solvent during the separation step, the precipitated polymer is separated from the fluid solvent without the fluid solvent being completely converted to 100% of the gas phase. Separation of the precipitated purer polymer is accomplished by any method of liquid-liquid or liquid-solid separation. Non-limiting examples of liquid-liquid or liquid-solid separation include filtration, decantation, centrifugation, and sedimentation.

[0307] In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polyethylene from a polyethylene / fluid solvent solution at a temperature and pressure, wherein the polyethylene precipitates from the solution. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 0°C to about 280°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 50°C to about 175°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the present invention, a process for purifying recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0308] In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polyethylene from the polyethylene / n-pentane solution at a temperature of about 0°C to about 280°C. In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polyethylene from the polyethylene / n-pentane solution at a temperature of about 30°C to about 150°C. In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polyethylene from the polyethylene / n-pentane solution at a temperature of about 50°C to about 130°C. In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polyethylene from the polyethylene / n-pentane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polyethylene from the polyethylene / n-pentane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0309] In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polypropylene from a polypropylene / fluid solvent solution at a temperature and pressure, wherein the polypropylene precipitates from the solution. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 100°C to about 200°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the present invention, the method for purifying a recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the present invention, a process for purifying recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0310] In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polypropylene from the polypropylene / propane solution at a temperature of about -42°C to about 220°C. In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polypropylene from the polypropylene / propane solution at a temperature of about 0°C to about 150°C. In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polypropylene from the polypropylene / propane solution at a temperature of about 50°C to about 130°C. In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polypropylene from the polypropylene / propane solution at a pressure of about 0 psig (0 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, the method for purifying the recycled polymer comprises separating the polypropylene from the polypropylene / propane solution at a pressure of about 50 psig (0.34 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises separating polypropylene from a polypropylene / propane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0311] In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / fluid solvent solution at a temperature and pressure wherein the polystyrene precipitates from the solution. In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 100°C to about 200°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0312] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure wherein the poly(dimethylsiloxane) precipitates from the solution. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 0° C. to about 220° C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115° C. to about 200° C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120° C. to about 180° C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 0 psig (0 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,000 psig (6.89 MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 500 psig (3.45 MPa).

[0313] In an embodiment of the invention, the filtered polymer is separated twice from the fourth solution to produce a purer polymer. In an embodiment of the invention, the filtered polymer is separated twice from the fourth solution at a temperature of about 0° C. to about 280° C. and a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa) to produce a purer polymer.

[0314] IX. Test Method

[0315] The test method described herein is used to measure the effectiveness of various methods for purifying polymers. Specifically, the method demonstrates the effectiveness of a given purification method in improving color and translucency / clarity (i.e., bringing the color and opacity of the recycled polymer closer to that of the uncolored virgin polymer), reducing or eliminating elemental contamination (i.e., removing heavy metals), reducing or eliminating non-combustible contaminants (i.e., inorganic fillers), reducing or eliminating volatile compounds (particularly those that contribute to the malodor of the recycled polymer), and reducing or eliminating polymer contamination (i.e., polyethylene contamination in polypropylene).

[0316] Color and opacity measurements

[0317] The color and opacity / translucency of polymers are important parameters in determining whether a polymer can achieve the desired visual aesthetic of articles made from it. Recycled polymers, particularly PCR polymers, are often dark and opaque due to residual pigments, fillers, and other contaminants. Therefore, color and opacity measurements are important parameters in determining the effectiveness of methods used to purify polymers.

[0318] Prior to color measurement, samples of either polymer powder or pellets were compression molded into square specimens (30 mm wide x 30 mm long x 1 mm thick) with rounded corners. The powder samples were first densified at room temperature (approximately 20-23°C) by cold-pressing the powder into a sheet, using clean, unused aluminum foil as a contact barrier between stainless steel plates. Approximately 0.85 g of the cold-pressed powder or pellets were then pressed into specimens on a Type C Carver Press (Carver, Inc., Wabash, IN46992-0554 USA) preheated to 200°C, using aluminum press plates, an unused aluminum foil barrier, and a stainless steel shim with a cavity corresponding to the aforementioned dimensions of the square specimen. The samples were heated for 5 minutes before applying pressure. After 5 minutes, the pressed product was compressed using at least 2 tons (1.81 metric tons) of hydraulic pressure for at least 5 seconds and then released. The molded stack was then removed and placed between two thick, flat metal heat sinks for cooling. The aluminum foil contact release layer was then peeled from the sample and discarded. The flash around the sample on at least one side was peeled back to the edge of the die, and the sample was then pushed through the form. Each specimen was visually evaluated for void / bubble defects, and only samples without defects in the color measurement area (0.7" (17.78 mm) minimum diameter) were used for color measurement.

[0319] Using the International Commission on Illumination (CIE) L 、 a 、 b Three-dimensional color space to characterize the color of each sample. L is a measure of the sample brightness, where L = 0 corresponds to the darkest black sample, while L = 100 corresponds to the brightest white sample. a is a measure of the redness or greenness of the sample, where positive values a corresponds to red, and negative values a Corresponds to green. Size b Is a measure of the blue or yellow color of the sample, positive values b corresponds to yellow, while negative values b The color of each square specimen, 30 mm wide × 30 mm long × 1 mm thick, was measured on a HunterLab LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-5280, USA). L a b The spectrophotometer was configured for D65 as the standard illuminant, a 10° observation angle, a 1.75” (44.45mm) area diameter viewing angle, and a 0.7” (17.78mm) port diameter.

[0320] The opacity of each sample was determined using the aforementioned Hunter Lab spectrophotometer using the contrast ratio opacity mode, which is a measure of how much light is transmitted through the sample (i.e., a measure of the translucency of the sample). Two measurements were taken to determine the opacity of each sample. One measurement measured the brightness value of the sample using a white backing as the background. , and once measure the brightness value of the sample with a black backing as the background The opacity is then calculated from the brightness value using the following equation: .

[0321] Elemental analysis

[0322] Many recycled polymers have unacceptably high levels of heavy metal contamination. The presence of heavy metals, such as lead, mercury, cadmium, and chromium, can prevent the use of recycled polymers in certain applications, such as food or drug contact applications or medical device applications. Therefore, measuring heavy metal concentrations is important when determining the effectiveness of methods used to purify polymers.

[0323] Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Test solutions were prepared by mixing approximately 0.25 g of sample with 4 mL of concentrated nitric acid and 1 mL of concentrated hydrofluoric acid (HF), with n = 2 to n = 6 depending on sample availability. Samples were digested using an Ultrawave microwave digestion protocol consisting of a 20-minute temperature ramp to 125°C, a 10-minute temperature ramp to 250°C, and a 20-minute hold at 250°C. The digested samples were cooled to room temperature. After adding 0.25 mL of 100 ppm Ge and Rh as internal standards, the digested samples were diluted to 50 mL. To assess measurement accuracy, pre-digested spikes were prepared by spiking virgin polymer. Samples spiked with virgin polymer were weighed using the same procedure described above, and the virgin polymer was spiked with the appropriate amounts of individual elements of interest, including Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb. Spikes were prepared at two different concentrations: a "low spike" and a "high spike." Each spiked sample was prepared in triplicate. In addition to spiking virgin polymer, billets were also spiked to confirm that no errors occurred during pipetting and to track recycling throughout the process. Billet spiked samples were also prepared in triplicate at two different concentrations and processed in the same manner as the spiked virgin polymer and test samples. A 9-point calibration curve was prepared by preparing solutions containing Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb at 0.05 ppb, 0.1 ppb, 0.5 ppb, 1 ppb, 5 ppb, 10 ppb, 50 ppb, 100 ppb, and 500 ppb. All calibration standards were prepared using 4 mL of concentrated nitric acid and 1 mL of concentrated HF by diluting pure standard reference solutions and 0.25 mL of 100 ppm Ge and Rh as internal standards. The prepared standards, test samples, and spiked test samples were analyzed using Agilent's 8800 ICP-QQQMS, optimized according to the manufacturer's recommendations. The m / z values ​​for each analyte monitored and the collision cell gas used for the analysis were as follows: Na, 23 m / z, H2; Al, 27 m / z, H2; Ca, 40 m / z, H2; Ti, 48 m / z, H2; Cr, 52 m / z, He; Fe, 56 m / z, H2; Ni, 60 m / z; no gas; Cu, 65 m / z, no gas; Zn, 64 m / z, He; Cd, 112 m / z; H2; Pb, total 206 ≥ 206, 207 ≥ 207, 208 ≥ 208 m / z, no gas; Ge, 72 m / z, all modes; Rh, 103 m / z, all modes. Ge was used as an internal standard for all elements less than 103 m / z, and Rh was used for all elements greater than 103 m / z.

[0324] Residual ash content

[0325] Many recycled polymers contain various fillers, such as calcium carbonate, talc, and glass fiber. While useful in the recycled polymer's original application, these fillers can alter the polymer's physical properties in ways that are undesirable in the next application of the recycled polymer. Therefore, measuring the amount of filler is important when determining the effectiveness of a method for purifying a polymer.

[0326] Thermogravimetric analysis (TGA) was performed to quantify the amount of non-combustible material (sometimes referred to as ash content) in the sample. Approximately 5-15 mg of sample was loaded onto a platinum sample pan and heated to 700°C in an air atmosphere at a rate of 20°C / min in a TA Instruments Q500 TGA instrument. The sample was held isothermally at 700°C for 10 minutes. After the isothermal hold, the residual mass percentage at 700°C was measured.

[0327] Odor analysis

[0328] Odor sensory analysis was performed by placing approximately 3g of each sample in a 20mL glass vial and equilibrating the sample at room temperature for at least 30 minutes. After equilibration, each vial was opened and the headspace was bunny-sniffed by a trained grader to determine odor intensity and descriptor characteristics. Odor intensity was rated on the following scale: 5 = very strong; 4 = strong; 3 = moderate; 2 = weak to moderate; 1 = weak; and 0 = no odor.

[0329] Polymer contamination analysis

[0330] Many recycled polymers, particularly those derived from mixed-stream sources, may contain undesirable polymer contaminants. Without wishing to be bound by any theory, polymer contamination (e.g., polyethylene contamination in polypropylene) can affect the physical properties of the polymer due to the presence of heterogeneous phases and the resulting weak interfaces. Furthermore, polymer contamination can increase the opacity of the polymer and affect its color. Therefore, measuring the amount of polymer contamination is important when determining the effectiveness of a method for purifying a polymer.

[0331] Differential scanning calorimetry (DSC) was used to assess semicrystalline polymer contamination. For example, to measure the amount of polyethylene contamination in polypropylene, a set of five polypropylene / polyethylene blends was prepared using 2, 4, 6, 8, and 10 wt% Formolene® HB5502FHDPE (Formosa Plastics Corporation, USA) in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, BV). Approximately 5-15 mg of each sample was sealed in an aluminum DSC pan and analyzed on a TA Instruments Q2000 DSC using the following method: 1. Equilibrate at 30.00℃ 2. Ramp up to 200.00°C at 20.00°C / min 3. Mark the end of cycle 0 4. Ramp up to 30.00°C at 20.00°C / min 5. Mark the end of cycle 1 6. Ramp up to 200.00°C at 20.00°C / min 7. Marking the end of period 2 8. Ramp up to 30.00°C at 20.00°C / min 9. Marking the end of cycle 3 10. Ramp up to 200.00°C at 5.00°C / min 11. Marking the end of cycle 4 The melting enthalpy of the HDPE peak around 128°C was calculated using the 5.00°C / min DSC thermogram for each sample with known HDPE content. Figure 2 As shown, a linear calibration curve was established by plotting the melting enthalpy against the known HDPE concentration (in wt %).

[0332] The same DSC equipment and method described above are used to analyze a sample with unknown PE content. The PE content is calculated using the calibration curve described above. The specific HDPE used to generate the calibration curve will likely have varying degrees of crystallinity, compared to any polyethylene (or polyethylene blend) contamination that may be present in the recycled polymer sample. Crystallinity can independently affect the measured melting enthalpy of the polyethylene and, therefore, the resulting calculation of the polyethylene content. However, the DSC test method described herein is intended as a relative measure for comparing the effectiveness of different methods for purifying polymers and is not meant to be a strict quantification of the polyethylene content in a polymer blend. Although the method described above describes the measurement of polyethylene contamination in polypropylene, it can be applied to other semicrystalline polymers using different temperature ranges and the measurement of peaks in DSC thermograms. In addition, alternative methods such as nuclear magnetic resonance (NMR) spectroscopy can also be used to measure the amount of semicrystalline and amorphous polymer contamination in a sample.

[0333] Analytical determination of chemical contaminants

[0334] For pesticides, the EN 15662:2018-07 Modular QuEChERS method was applied. For alkylphenol ethoxylates, alkylphenols, and bisphenols, the following technique was used: samples were cut, homogenized, and weighed; then, an internal standard (deuterated bisphenol A) was added, and the samples were extracted with hexane at room temperature. Derivatization was performed with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide), and contaminant levels were determined by GC-MSD. For dioxins, furans, and PCBs, the ISO / IEC 17025:2005 method was applied. The sample was cut into small pieces, and a 13C / 12C-labeled PCDD / F internal standard was added to an aliquot of the sample material. The sample was extracted with hexane and H2SO4 for 1 hour to disrupt the matrix, followed by re-extraction with hexane (three times for 30 minutes). A multi-step chromatographic cleanup was applied, and a 13C / 12C-labeled PCDD / F recovery standard was added to the measurement solution. Quantification was performed using an internally labeled PCDD / F standard (isotope dilution and internal standard techniques). For organotin: The method followed the EDANA protocol for organotin compounds in absorbent hygiene products and their constituent raw materials (WSP 351). More specifically, the sample was extracted with ethanol containing a sodium diethyldithiocarbamate solution, alkylated with sodium tetraethylborate, and transferred to an organic phase by extraction with hexane. The tetrasubstituted organotin compounds were then separated by capillary gas chromatography, using either AED or MS as a detector. GC-ICP-MS was used as the detector system for organometallic analysis. For phthalates: The sample was cut, homogenized, and weighed. The sample was then extracted with hexane at room temperature using an internal standard. The extracted phthalates were then identified and quantified by GC-MSD. For PAHs: The sample was cut, homogenized, and weighed. A deuterated PAH internal standard was then added and the sample was extracted with hexane. The extracted PAHs were purified using silica gel, concentrated, and characterized by GC-MSD.

[0335] Amount of loosely bound surface contaminants

[0336] The amount of loosely bound surface contamination is determined by the following method: Approximately 20 g of plastic is added to a 1,000 mL round-bottom flask. Approximately 300 mL of distilled water is added to the 1,000 mL round-bottom flask. The round-bottom flask is capped and shaken vigorously for approximately 60 seconds. The water is decanted from the flask. Approximately 600 mL of additional distilled water is added to the 1,000 mL flask and immediately decanted, leaving the original regenerated polymer with a small amount of water. The regenerated polymer is removed from the round-bottom flask and dried in a convection oven at 60°C overnight. The % change in mass of the plastic is the amount of loosely bound surface contamination.

[0337] Color measurements for ΔE calculations

[0338] Color measurements were obtained using a Minolta spectrophotometer, Model CM580d. The "white" portion of the Leneta card served as a common background and as a reference point for ΔE calculations. ΔE is the color difference between the sample color and the reference color. Color measurements were performed using a D65 illuminant and a 10° observer. A minimum of three measurements were taken for each sample of the compressed thermoplastic starch composition. The L, a, and b values ​​were averaged and reported along with the ΔE value. A pure white Leneta card has a ΔE value of zero, and positive deviations from zero indicate increased discoloration. Those skilled in the art will appreciate how to calculate ΔE values.

[0339] X. Example

[0340] Comparative Example 1 - Purification of high-shelf commercial Posterior membrane

[0341] Recycled polymer consisting of high-shelf commercial post-film #1 was fed into a commercially available purification process. The cleaning process consisted of shredding, various water washing steps, drying, and melt densification. Shredding homogenized the material while reducing its primary dimensions. Aqueous solution washing should effectively remove surface contamination. However, due to the low solubility of chemical contaminants in water, this process's ability to remove large amounts of permeable contaminants should be minimal. Small amounts of volatile bulk contaminants should be removed during drying and melt densification, but overall, bulk contamination should be largely unaffected. Furthermore, the high-shelf commercial post-film source used as the recycled polymer had limited chemical contamination, as evidenced by low levels of pesticides, dioxins, and phthalates. The recycled polymer and purer plastics were analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) for the types of chemical contaminants commonly found in recycled materials using the methods disclosed in Section IX. After purification, the purer plastics contained slightly reduced levels of chemical contaminants, as shown in Table 3. The removal efficiencies for the five selected substances were as follows: 4-tert-amylphenol, the removal efficiency was 0%. Bisphenol A, the removal efficiency was 94%. OCDD, the removal efficiency was 78%. PCB 118, the removal efficiency was 68%. Di-2-ethylhexyl phthalate, the removal efficiency was 22%. The average removal efficiency for the five selected pollutants was approximately 52%.

[0342] Table 3

[0343] Use commercially available water wash method #1

[0344] To purify high-care commercial post (HCPC) source #1

[0345] Comparative Example 2—Purification of high-shelf commercially available water-washing process #2 followed by melt densification Post Film #2

[0346] Recycled polymer, consisting of high-shelf commercial post-film #2, was fed into a commercially available purification process to produce purer plastics. The cleaning process consisted of shredding, hot water washing, drying, and melt densification. As with water wash process #1, this process should remove surface contamination, but its ability to remove large amounts of permeable contamination was limited. The recycled polymer and purer plastics were analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 4. The high-shelf film source (recycled polymer) had limited chemical contamination, as evidenced by low levels of dioxins, PCBs, phthalates, and PAHs. The purer plastics contained a mixture of increased and slightly decreased levels of chemical contamination. The increase in some chemical contaminants may be due to cross-contamination from other, more heavily contaminated feed streams and / or variability in the contamination levels of the current feed. The removal efficiencies for the five selected substances were as follows: 4-tert-amylphenol, the removal efficiency was 0%. Bisphenol A, the removal efficiency was 96%. OCDD, the removal efficiency was 0%. PCB 118, the removal efficiency was 68%. Di-2-ethylhexyl phthalate, the removal efficiency was 0%. The average removal efficiency for the five selected pollutants was approximately 14%.

[0347] Table 4

[0348] Use commercially available water wash method #2

[0349] To purify High-Care Commercial Post (HCPC) Source #2

[0350] Comparative Example 3A - Commercial Post #1 membrane was purified using a commercially available deinking process from Cadel.

[0351] Recycled polymer composed of commercial post-film #1 was fed into a purification process commercially available from Cadel called deinking (http: / / cadeldeinking.com / en / ) to produce a purer plastic. The process consists of shredding, aqueous deinking, aqueous washing / rinsing, and drying. Based on patented technology, the deinking step involves elevated temperatures, elevated pH, and surfactants. The various washing steps should effectively remove surface contamination. Furthermore, a small amount of bulk permeable contamination will be removed due to the elevated temperature, which increases diffusion rates, and the solubility of contaminants in water may increase due to the surfactant / pH combination. However, the overall extraction yield is expected to be low. The incoming recycled polymer was measured to have 0.125 wt% of loosely bound surface contamination, compared to approximately 0.02 wt% for the purer plastic in chip form. Therefore, this cleaning process removes greater than 80% of the incoming loosely bound surface contamination. After cleaning, but before analyzing the recycled polymer for chemical contamination, the chip melt was densified using a single-screw extruder at 190°C to produce pellets. The pellets were ground to an average diameter of 300 to 500 μm. The recycled polymer and purer plastics were analyzed for chemical contaminants typically found in recycled materials by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 5. The recycled polymer contained moderate levels of chemical contamination, indicating a lack of a high-shelf lifecycle for commercial post-use films. For example, incoming dioxins such as OCDD were 40 times the LOQ, which is higher than the high-shelf sources described previously in Comparative Examples 1, 2, and 5. Furthermore, this particular source had high levels of paper contamination, which could potentially contribute to additional chemical contamination once remelted for densification / pelletization. This particular source was particularly high in alkylphenols (approximately 1,000 times the LOQ), further demonstrating the level of chemical contamination within this recycled source. The recycled polymer consisted of shredded film, much of which was melted together into plastic blocks. Therefore, the effectiveness of surface cleaning techniques using this source is somewhat limited by the lack of access to fully contaminated surfaces. After the deinking process, the resulting plastic is purer and contains reduced levels of chemical contamination. Removal efficiency for the five selected substances was as follows: 4-tert-amylphenol was 71% efficient. Bisphenol A was 0% efficient. OCDD was 60% efficient. PCB 118 was 0% efficient. Di-2-ethylhexyl phthalate was 22% efficient. The average removal efficiency for the five selected contaminants was approximately 31%.

[0352] Comparative Example 3B - Post-domestic membrane #1 was purified using a commercially available deinking process from Cadel.

[0353] The recycled polymer consisting of post-domestic film #1 was fed into the surface purification process of Comparative Example 3A to produce a purer plastic. The introduced recycled polymer was measured to have 0.047% by weight of loosely bound surface contamination, compared to approximately 0.003% by weight of the purer plastic. Thus, the cleaning process removed more than 80% of the incoming loosely bound surface contamination. Prior to analysis for chemical contamination, the fragments of post-domestic film #1 were melt densified and pelletized using an extruder. The granular material was ground to an average particle size of 300 μm to 500 μm. The types of chemical contaminants commonly found in recycled materials in the recycled polymer and the purer plastic were analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 5. The recycled polymer contained extremely high levels of chemical contamination, including significant dirt. For example, the pesticide piperonyl butoxide was approximately 7 times the LOQ; alkylphenol ethoxylates were approximately 1,000 times the LOQ; and dioxins and phthalates were approximately 300 times the LOQ. Purer plastics contain reduced levels of chemical contamination. Note: Despite using the same cleaning process, the difference in removal efficacy between Comparative Example 3A and Comparative Example 3B may be due to: 1) differences in surface area exposed by the cleaning process; 2) differences in the distribution of chemical contaminants on the surface and within the bulk; and 3) inherent variability in chemical contaminants within the sample and variability in the measurement technique. Removal efficiencies for the five selected substances were as follows: For 4-tert-amylphenol, the removal efficiency was 38%. For bisphenol A, the removal efficiency was 92%. For OCDD, the removal efficiency was 21%. For PCB 118, the removal efficiency was 0%. For di-2-ethylhexyl phthalate, the removal efficiency was 73%. The average removal efficiency for the five selected contaminants was approximately 45%.

[0354] Table 5

[0355] Purification of post-commercial (PC) source #1 and post-home (PH) using a commercially available deinking process from Cadel Source #1

[0356] Comparative Example 4 - Purification of High-Performance Commercial Post-#3 Membrane Using a Commercially Available Deodorization Method

[0357] Recycled polymer composed of high-shelf commercial post-film #3 was fed into a purification process known as deodorization technology. This process involves exposing the granular feed to moderate temperatures and continuous air flushing. Therefore, this cleaning technology primarily removes volatile surface and bulk contaminants. However, most chemical contaminants associated with controlled end markets are highly non-volatile. Recycled polymer and purer plastics were analyzed for chemical contaminants commonly found in recycled materials by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 6. High-shelf film source #3 had limited chemical contamination, as evidenced by low levels of dioxins, PCBs, phthalates, and PAHs. Purer plastics contained slightly reduced levels of chemical contamination. Removal efficiencies for five selected substances were as follows: 4-tert-amylphenol, removal efficiency was 88%. Bisphenol A, removal efficiency was 96%. OCDD, removal efficiency was 20%. For PCB 118, the removal efficiency was 0%. For di-2-ethylhexyl phthalate, the removal efficiency was 0%. The average removal efficiency for the five selected pollutants was approximately 41%.

[0358] Table 6

[0359] Purification using commercially available deodorization methods

[0360] High-Care Commercial Post-Use (HCPC) Source #3

[0361] Typically, established methods for purifying / cleaning film and other plastic waste, including water washing, deinking, and devolatilization, currently do not adequately remove chemical contaminants, especially from high-safety sources. Even with high-safety sources, chemical contamination remains and is not completely removed, which can limit end-use applications for some consumers. Consequently, there is an unmet need for cleaning technologies that can more completely remove chemical contamination sufficient for use in highly contaminated sources and for any market requiring purer recycled material.

[0362] Example 1 - Submerged Immersion of Domestic Post-Membrane #1 Using Ethyl Acetate in a CSTR at Boiling Temperature and Atmospheric Pressure Overall purification

[0363] 2,000 g of ethyl acetate was added to a 5 L stirred round bottom flask. The flask was equipped with a mechanical stirrer, a reflux condenser and a heating jacket. The mechanical stirring was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. Heat was applied to bring the ethyl acetate to a rapid boil (about 77.1°C) in about 10 minutes. After the boiling point of the ethyl acetate was reached, the heat input was reduced to achieve a consistent reflux rate of about 10 ml / min at a boiling point of about 77.1°C. Home Post Film #1 was added to the round bottom flask containing the boiling ethyl acetate. About 110 g to 120 g of Home Post Film #1 in the form of chips was added. The thickness of the chips was about 20 μm to 30 μm. Therefore, the surface area to volume ratio of the recycled polymer was about 80 mm -1 . Stirring is sufficient to completely exfoliate the membrane fragments within the ethyl acetate and prevent them from agglomerating. Continue extraction for approximately 45 minutes. Stop stirring and remove heat. Decant the ethyl acetate from the fragments. Add an additional 2,000 g of preheated fresh ethyl acetate at or near boiling point to the plastic fragments in the 5 L round-bottom flask to complete the second extraction step. Begin stirring at 400 to 500 rpm while applying heat sufficient to reflux the ethyl acetate at approximately 10 mL / min. The time to reach reflux after adding fresh ethyl acetate to the fragments is approximately 5 minutes. The second extraction lasts a total of approximately 45 minutes. Stop stirring and remove heat. Decant the ethyl acetate and place the membrane fragments in a filter flask without vacuum to further remove residual ethyl acetate. The membrane fragments are then dried at room temperature overnight. For both stages, the leaching solvent to regenerated polymer ratio for each stage is approximately 18:1, resulting in a total solvent to regenerated polymer ratio of approximately 36:1. The leaching time for each stage is approximately 50 minutes per stage, for a total time of approximately 100 minutes. The dried film fragments were placed in a Pharma 11 small twin-screw compounder at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm to produce the final, purer plastic. The purer plastic was analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX for chemical contaminants commonly found in recycled materials, as shown in Table 7. For the contaminant 4-tert-amylphenol, the removal efficiency was 93%. For the contaminant bisphenol A, the removal efficiency was 85%. For the contaminant OCDD, the removal efficiency was 97%. For PCB 118, the removal efficiency was 90%. For di-2-ethylhexyl phthalate, the removal efficiency was 79%. The average removal efficiency for the contaminants 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate was 89%.

[0364] Table 7

[0365] Using ethyl acetate in a CSTR at boiling point and atmospheric pressure

[0366] Purification of Submerged Leached Home (PH) Membrane #1

[0367] Example 2 - Immersion Soaking of Domestic Post-Membrane #1 Using Ethyl Acetate in a CSTR at Boiling Temperature and Atmospheric Pressure Overall purification .

[0368] About 110 to 120 g of home-use post-film #1 in the form of film fragments (surface area to volume ratio of about 80 mm -1) was added to a 5L round-bottom flask. The flask was equipped with a mechanical stirrer, a reflux condenser, and a heating jacket. The mechanical stirring was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. 2000 g of ethyl acetate was heated to boiling in a separate round-bottom flask. 2000 g of boiling ethyl acetate was added to the 5L round-bottom flask containing the membrane fragments. Heat was applied to quickly achieve boiling conditions. Stirring at 400 rpm was sufficient to prevent membrane agglomeration and achieve good exfoliation. Once boiling was achieved (approximately 5 minutes), the heat was reduced to produce a solvent reflux rate of approximately 10 ml / min at approximately 77.1°C. Leaching was continued for a total of 20 to 25 minutes. After approximately 25 minutes, the heat was removed and the ethyl acetate was decanted from the fragments. A second 2000 g of preheated, freshly boiling ethyl acetate was added to the fragments in the 5L round-bottom flask to complete the second leaching stage. Stirring was initiated at 400 to 500 rpm while applying heat sufficient to reflux at 10 mL / min. The time to reach reflux was approximately 5 minutes. The second leaching lasted a total of 25 minutes. The heat was removed and stirring stopped. The ethyl acetate was decanted, and the membrane fragments were then added to a filter funnel on a vacuum-free filter flask. After approximately 10 minutes, the fragments were placed on a baking sheet and the solvent was allowed to evaporate overnight. For both stages, the leaching solvent to recycled polymer ratio for each stage was approximately 18:1, resulting in a total leaching solvent to recycled polymer ratio of approximately 36:1. The leaching time for each stage was approximately 30 minutes, for a total of approximately 60 minutes. The dried membrane fragments were placed in a Pharma 11 mini twin-screw compounder at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm to produce the final, purer plastic. The purer plastics were analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 8. For the contaminant 4-tert-amylphenol, the removal efficiency was 90%. For the contaminant bisphenol A, the removal efficiency was 79%. For the contaminant OCDD, the removal efficiency was 97%. For the contaminant PCB 118, the removal efficiency was 82%. For di-2-ethylhexyl phthalate, the removal efficiency was 98%. The average removal efficiency for the contaminants 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate was 89%.

[0369] Despite the shorter leaching time of Example 2, the overall removal efficiencies of Examples 1 and 2 are very similar, indicating that the leaching is solvent tank limited rather than time limited. Therefore, the leaching could potentially be operated with a shorter overall time, but with more stages and / or a slightly higher leaching solvent to regenerated polymer mass ratio to improve removal.

[0370] Table 8

[0371] Using ethyl acetate in a CSTR at boiling point and atmospheric pressure

[0372] Immersion leaching purification home use (PH) membrane #1

[0373] Example 3 - Whole-house post-membrane #1 using submerged leaching of THF in a CSTR at boiling point and atmospheric pressure Body purification .

[0374] 2,000 g of THF was added to a 5 L stirred round bottom flask. The flask was equipped with a mechanical stirrer, a reflux condenser, and a heating jacket. The mechanical stirring was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. Heat was applied to bring the THF to a rapid boil (about 66° C.) in about 10 min. After the boiling point of THF was reached, the heat input was reduced to achieve a consistent reflux rate of about 10 ml / min at a boiling point of about 66° C. Home Post Film #1 was added to the round bottom flask containing the boiling THF solvent. About 110 to 120 g of Home Post Film #1 in the form of flakes (surface area to volume ratio of about 80 mm -1). Stirring was sufficient to completely exfoliate the membrane fragments from the THF and prevent them from agglomerating. Leaching continued for approximately 45 minutes. Stirring was stopped and the heat removed. The THF was decanted from the fragments. An additional 2,000 g of preheated fresh THF at or near boiling point was added to the plastic fragments in the 5 L round-bottom container to complete the second leaching step. Stirring was initiated at 400 to 500 rpm while applying sufficient heat to bring the THF to reflux at approximately 10 mL / min. The time to reach reflux after adding fresh THF to the fragments was approximately 5 minutes. The second leaching lasted a total of approximately 45 minutes. Stirring was stopped and the heat removed. The THF was decanted and the membrane fragments were then placed in a filter flask without vacuum to further remove residual THF. The membrane fragments were then dried at room temperature overnight. For both stages, the leaching solvent to regenerated polymer ratio for each stage was approximately 18:1, resulting in a total leaching solvent to regenerated polymer ratio of approximately 36:1. The leaching time for each stage was approximately 50 minutes, for a total leaching time of approximately 100 minutes. The dried film fragments were placed in a Pharma 11 small twin-screw compounder at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm to produce the final, purer plastic. The purer plastic was analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX for chemical contaminants commonly found in recycled materials, as shown in Table 9. For the contaminant 4-tert-amylphenol, the removal efficiency was 98%. For the contaminant bisphenol A, the removal efficiency was 91%. For the contaminant OCDD, the removal efficiency was 96%. For PCB 118, the removal efficiency was 67%. For di-2-ethylhexyl phthalate, the removal efficiency was greater than 98%. The average removal efficiency for the contaminants 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate was 90%.

[0375] Table 9

[0376] Using THF in a CSTR at boiling point and atmospheric pressure

[0377] Purification of the submerged leached household (PH) membrane #1

[0378] Example 4 - Surface washing by Cadel deinking and the use of Combination of Bulk Purification with Submerged Leaching Using Home Rear Membrane #1 and Ethyl Acetate

[0379] Recycled polymer composed of post-domestic film #1 was purified as in Comparative Example 3B to produce a purer plastic #1 (surface area to volume ratio of approximately 8 mm -1). The purer plastic #1 was fed to the overall purification step of the extraction as follows: Approximately 110 g to 120 g of the purer plastic from Comparative Example 3B in the form of membrane fragments was added to a 5 L round-bottom flask. The flask was equipped with a mechanical stirrer, a reflux condenser, and a heating jacket. The mechanical stirring was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. 2000 g of ethyl acetate was heated to boiling point in a separate round-bottom flask. 2000 g of boiling ethyl acetate was added to the 5 L round-bottom flask containing the membrane fragments. Heat was applied to quickly achieve boiling conditions. Stirring at 400 rpm was sufficient to prevent membrane agglomeration and achieve good exfoliation. Once boiling was achieved (approximately 5 minutes), the heat was reduced to produce a solvent reflux rate of approximately 10 ml / min at approximately 77.1°C. Leaching was continued for a total of 20 to 25 minutes. After approximately 25 minutes, the heat was removed and the ethyl acetate was decanted from the fragments. A second 2000 g of preheated, freshly boiled ethyl acetate was added to the chips in the 5 L round-bottom flask to complete the second leaching stage. Agitation was initiated at 400 to 500 rpm while heating was applied to reflux at 10 mL / min. The time to reflux was approximately 5 minutes. The second extraction lasted a total of 25 minutes. The heat was removed and agitation stopped. The ethyl acetate was decanted, and the membrane chips were then added to the filter funnel on the vacuum-free filter flask. After approximately 10 minutes, the chips were p...

Claims

1. A method for purifying a recycled polymer, the method comprising: a. obtaining the recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b. leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between atmospheric pressure and 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a leached polymer comprising at least one of the alkylphenol, bisphenol, dioxin, PCB, or phthalate, each having a concentration; and wherein the average removal efficiency is greater than 55%; c. dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a first solution comprising the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; d. settling the first solution at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of the at least one suspended contaminant; e. filtering the second solution by mechanical filtration at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a third solution comprising a filtration polymer, at least one dissolved contaminant, and even less of the at least one suspended contaminant; f. filtering the third solution by adsorption filtration at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a fourth solution comprising twice-filtered polymer; as well as g. separating the twice filtered polymer from the fourth solution to produce a purer polymer; and wherein the second fluid solvent has the same chemical composition as the first fluid solvent or a different chemical composition.

2. The method according to claim 1, wherein the alkylphenol, bisphenol, dioxin, PCB and phthalate ester include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate.

3. The method of claim 1 , wherein the number of leaching stages is between 1 and 50.

4. The method of claim 1, wherein the regenerated polymer has an average surface area to volume ratio greater than 1 mm-1.

5. The method of claim 1, wherein the total residence time of the leaching step is less than 360 minutes.

6. The method according to claim 1, wherein the leaching solvent is at least one of DME, diethyl ether, MEK, ethyl acetate, THF, acetone, methanol and CO2 or a mixture thereof.

7. The method of claim 2, wherein the leaching temperature is between 20° C. and 90° C., and the leaching pressure is between atmospheric pressure and 1,000 atm; wherein the leaching solvent is ethyl acetate; wherein the total residence time of the leaching step is less than 360 minutes; and wherein the average removal efficiency is 55%.

8. The method of claim 1 , wherein, prior to the leaching step, the regenerated polymer is surface washed in a non-densified state in a surface washing step to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination of greater than about 80%; wherein the regenerated polymer has an average surface area to volume ratio of greater than 1 mm −1 before surface washing; wherein the surface washing process is of a deinking type; wherein the deinking process results in a ΔE change of less than 10% between the deinked polymer and the regenerated polymer without surface printing ink; wherein the leaching step is carried out in a continuously stirred tank reactor (CSTR); wherein the leaching solvent is ethyl acetate; wherein the CSTR comprises 3 leaching stages; wherein the leaching temperature is 77° C. and the leaching pressure is near atmospheric pressure; wherein the residence time of each of the leaching stages is 20 minutes; wherein the average removal efficiency is greater than 55%; and wherein the leached polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets.

9. The method of claim 1, wherein the filtration polymer is separated from the fourth solution at a temperature of 0°C to 280°C and a pressure of 0 psig (0 MPa) to 2,000 psig (13.79 MPa).

10. The method of claim 1, wherein the leaching polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of at least 0.5% by weight.

11. The method of claim 1, wherein the regenerated polymer is a PCR polymer.

12. The method of claim 1, wherein the fluid solvent has a normal boiling point less than 0°C and greater than -45°C and a normal enthalpy change of vaporization less than +25 kJ / mol.

13. The method of claim 1, wherein the fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof.

14. The method of claim 1, wherein the temperature in the dissolving, settling, and filtering steps is 110°C to 220°C, and the pressure in the dissolving, settling, and filtering steps is 400 psig (2.76 MPa) to 2,600 psig (17.93 MPa).

15. A method for purifying a recycled polymer, the method comprising: a. obtaining the recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b. surface washing the regenerated polymer in a non-densified state to produce a surface washed polymer; wherein said surface washing results in a reduction of loosely bound surface contamination by greater than about 80%; c. leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between atmospheric pressure and 1,000 atm at an average removal efficiency over a total residence time and a residence time in each of the leaching stages to produce a leached polymer comprising at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate, wherein the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate each have a concentration; wherein the average removal efficiency is greater than 55%; d. dissolving the leached polymer in a solvent selected from the group consisting of the first fluid solvent, the second fluid solvent, and mixtures thereof at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a first solution comprising a dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; e. settling the first solution at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of the at least one suspended contaminant; f. filtering the second solution by mechanical filtration at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a third solution comprising a filtration polymer, at least one dissolved contaminant, and even less of the at least one suspended contaminant; g. filtering the third solution by adsorptive filtration by contacting the third solution with one or more solid media at a temperature of 90° C. to 280° C. and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a fourth solution comprising a twice filtered polymer; as well as h. separating the twice filtered polymer from the fourth solution to produce a purer polymer; and wherein the second fluid solvent has the same chemical composition as the first fluid solvent or a different chemical composition.

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