Method for purifying regenerated polymer

Abstract

A process for purifying a regenerated polymer to a purer polymer is disclosed. In embodiments of the invention, the method involves obtaining a regenerated polymer, leaching 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. And settling, filtering and extracting the first solution. 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 polymers into purer polymers by combining a submersion leaching step and a purification step and using a leaching solvent and a pressurized solvent. More specifically, the recycled polymers are selected from post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof. The purer polymers are colorless or clear, odorless, and virgin-like polymers. The present invention is particularly suitable for purifying polyolefins, such as polyethylene and polypropylene. BACKGROUND

[0002] Synthetic polymers are ubiquitous in daily life due to their relatively low production cost and well-balanced material properties. They are widely used in various applications, such as packaging, automotive parts, medical devices, and consumer goods. To meet the high requirements of these applications, hundreds of millions of tons of synthetic polymers are produced globally every year. The vast majority of these polymers are produced from increasingly scarce fossil resources, such as petroleum and natural gas. Additionally, the manufacturing of these synthetic polymers from fossil sources results in the emission of greenhouse gases (GHG), primarily CO2, into the atmosphere.

[0003] The widespread use of synthetic polymers results in millions of tons of plastic waste every year. While most plastic waste is landfilled through municipal solid waste programs, a significant portion of plastic waste is found in the environment as litter, which is unsightly and can be harmful to ecosystems. Plastic waste is often washed into river systems and eventually into the ocean.

[0004] Plastic recycling has emerged as a solution to mitigate the problems associated with the widespread use of plastics. Recycling and reusing plastics divert waste from landfills and reduces the demand for virgin plastics made from fossil-based resources, which in turn reduces GHG emissions. In developed regions, such as the United States and the European Union, plastic recycling rates are rising due to increased awareness among consumers, businesses, and industrial manufacturers. Most recycled materials, including plastics, are mixed into a single stream, which is collected and processed by material recovery facilities (MRFs). At MRFs, 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 streams or mixed streams can then be further sorted, washed, and reprocessed into pellets suitable for reuse in plastic processing, such as blow molding, profile extrusion, injection molding, and film making, in plastic recycling facilities (PRFs).

[0005] Despite the fact that recycled plastics are sorted into major homogeneous streams and washed with aqueous and / or caustic solutions, the final reprocessed pellets are often highly contaminated with unwanted waste impurities such as spoiled food residue and residual flavor components. In addition, recycled plastic pellets, except those from recycled beverage containers, are dark in color due to the mixture of dyes and pigments typically used to color plastic articles. While there are some applications that are insensitive to color and contamination (e.g., black plastic paint containers and hidden automotive parts), most applications require colorless pellets. The demand for high quality “virgin-like” recycled resins is especially important for food and pharmaceutical contact applications such as food packaging. In addition to being contaminated with impurities and mixed colorants, many recycled resin products are often heterogeneous in chemical composition and can 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 compared to virgin plastics. The key to increasing recycling rates and reducing GHG emissions and plastic pollution is to reduce contamination to levels that allow for more widespread use in more end markets, especially those involving demanding applications.

[0007] Films are a special case of recycled plastics and are predominantly polyolefins in composition. Films present unique challenges for recycling that have not been solved. The recycling film supply stream can be divided into two general categories: 1) pre-consumer recycled films, which include in-plant scrap / offcuts and PIR films that can be reused in the same process that produced the film, films produced from in-plant scrap that were not used in the same process that produced them; and 2) PCR films, including post-commercial recycling films and post-home recycling films, the post-commercial recycling films are films that have been used in commerce but not directly by a household consumer (e.g., store post-shrink wrap, pallet wrap, bulk bags, furniture wrap, agricultural films, etc.), the post-home recycling films are films that have been used directly by a household consumer in commerce (e.g., retail bags, retail food packaging, outer packaging of diapers and hygiene products, trash bags, etc.). PIR film scrap for recycling is collected on a factory-by-factory basis at controlled end markets and can or can not involve (or require) significant cleaning steps prior to recycling. PCR films are collected at the point of sale and shipped to various PRFs dedicated to films for various cleaning operations and ultimately distributed to end markets. In the United States, post-home films are primarily collected in store recycling programs where the end consumer returns the film to collection bins at local stores. Film-based PRFs collect the film scrap and ship it to end markets after sorting and washing. Film recycling materials have very limited use due to contamination. Films are more contaminated than other forms because of the higher ratio of surface area to volume, which makes the opportunity for external contamination greater. Currently, most film-based recycled plastics are cycled down into non-circular and limited size markets, such as plastic lumber. As film-based scrap collection grows, the need for end markets beyond plastic lumber is imperative. Ideally, film-based scrap will ultimately find re-use in film-based applications, thereby ensuring continued cycling.

[0008] End markets cannot grow unless contamination is greatly reduced. Given the large amount of film used in demanding applications, it is important that recycled plastics from these markets re-enter the same end markets to support circularity. Therefore, the ability to remove even higher levels of contaminants is critical to achieving circularity and reducing GHG emissions and plastic pollution. Plastic pollution is even more problematic for films given the large surface area used per use and the mobility of scrap through air and water in the environment.

[0009] While contamination is problematic for all end-market applications, demanding applications have even more stringent requirements, especially for certain chemical contaminants. Depending on the chemical structure of the contaminant, the relevant chemical contaminants are classified into various chemical classes. 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, isothiazolines, glyphosate, alkylphenols, alkylphenol ethoxylates, aromatic amines, and flame retardants. Furthermore, target levels of these contaminants can be extremely low. For example, target levels can be in the order of parts per million (ppm), parts per billion (ppb), and parts per trillion (ppt), where the initial contaminated plastic can contain levels that are 1,000 times 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 S. M. Al-Salem, P. et al., “Recycling and reprocessing of plastic materials: a state of the art 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. While advances in mechanical recycling technology have improved the quality of recycled polymers to some extent, mechanical purification methods still have fundamental limitations, such as physical entrapment of pigments within the polymer matrix. Thus, even with improvements in mechanical recycling technology, the high levels of dark color and chemical contamination in currently available recycled plastic waste hinders the widespread use of recycled resins by the plastics industry. For film-based materials, there are dry and wet processes. In the dry process, the controlled film stream is typically shredded, dried, and then melt-extruded into the final form. Melt filtration and devolatilization are typically part of the extrusion step. In the wet process, the controlled film stream is typically shredded, 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 processes are generally acceptable in removing intentional surface contamination such as paper labels and unintentional surface contamination such as dirt, but are poor at removing bulk contaminants.

[0011] U.S. Patent 10,022,725 discloses a mechanical recycling process for cleaning linear low density polyethylene (LLDPE) / LDPE film for recycling. The '725 patent also discloses steps of shredding, a first water wash step, a second pulverization step involving wet milling, one or more attrition wash steps using hot water in at least one step, a drying or multiple drying steps, and a compaction step. This process can be quite effective in removing certain loosely bound surface contaminants, but will be ineffective in removing bulk contaminants because of the very low solubility of bulk contaminants in aqueous wash media and / or the limited diffusivity of bulk contaminants within the plastic.

[0012] U.S. Patent 9,616,595 discloses a mechanical recycling process for de-inking surface printed plastic film. The '595 patent also discloses steps of grinding, an ink removal step, general washing, cleaning solution recovery, recovering pigments, and drying. The ink removal step involves the use of an aqueous cleaning fluid with high pH and selective cleaning agents such as dodecyl sulfate and high turbulence. This process claims the ability to remove surface printed inks, which upon heating during recycling can result in chemical contamination. This process will have limited ability to remove bulk contaminants because of the limited solubility of bulk contaminants in aqueous wash media and / or the limited diffusivity of bulk contaminants within the plastic.

[0013] To overcome the fundamental limitations of mechanical recycling, many processes have been developed to purify contaminated polymers via chemical methods or chemical recycling. These processes mostly use solvents to clean and purify polymers. The use of solvents enables the extraction of impurities and the dissolution of polymers, which further enables optional separation techniques. For example, U.S. Patent 7,935,736 describes a process for recycling polyesters from waste containing polyesters using solvents to dissolve the polyesters prior to cleaning. The '736 patent also describes the need to recover the polyesters from the solvents using a precipitant.

[0014] U.S. Patent 6,555,588 describes a process for producing polypropylene blends from plastic mixtures containing other polymers. The '588 patent describes extracting contaminants from the polymers at temperatures below the dissolution temperature of the polymers in a selected solvent such as hexane for a specific residence time. The '588 patent also describes increasing the temperature of the solvent (or a second solvent) to dissolve the polymers 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 wt% of polyethylene contaminants.

[0015] European Patent Application 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 a polyolefin mixture or waste with a hydrocarbon fraction of gasoline fuel 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 extraneous components from the solution. The '312 patent also describes cooling the solution to a temperature below 70°C to crystallize the polyolefin, and then removing the adhering solvent by heating the polyolefin above the melting point of the polyolefin, or evaporating the adhering solvent in a vacuum or passing a gas stream through the polyolefin to precipitate, and / or extracting the adhering solvent with an alcohol or ketone having a boiling point below the melting point of the polyolefin.

[0016] U.S. Patent 5,198,471 discloses a method for separating a polymer from a physically mixed solid mixture containing a plurality of polymers (e.g., waste plastics) at a first lower temperature using a solvent 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 not dissolved at the first lower temperature. The '471 patent describes filtration of the insoluble polymer component.

[0017] U.S. Patent 5,233,021 describes a method for extracting pure polymer components from a multi-component structure (e.g., a discarded carpet) by dissolving the components in a supercritical fluid at suitable temperatures and pressures, and then changing 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 components.

[0018] U.S. Patent 5,739,270 describes a method and apparatus for continuously separating polymer components of a plastic from contaminants and other components of the plastic using a co-solvent and a working fluid. The co-solvent at least partially dissolves the polymers, and a second fluid (i.e., in a liquid, critical, or supercritical state) solubilizes components from the polymers, and precipitates some of the polymers dissolved in the co-solvent. The '270 patent also describes a step of filtering the thermoplastic co-solvent (with or without the working fluid) to remove particulate contaminants (such as glass particles).

[0019] U.S. Patent 5,368,796 discloses a method for surface cleaning polyethylene film. The '796 patent also discloses the following steps: shredding, a first surface washing step involving a boiling solvent at a temperature below the melting temperature of the polyethylene and at or near ambient pressure, with the application of 30 min of vigorous mechanical agitation to rub off the ink, a second surface washing step involving fresh solvent below the melting temperature of the polyethylene, with the application of 30 min of vigorous mechanical agitation, a third surface washing step involving solvent below the melting temperature of the polyethylene, with the application of 30 min to 60 min of vigorous mechanical agitation, and devolatilization, and melt densification. Optionally, the method can include a water washing step prior to treatment with solvent to remove surface dirt. The '796 patent also discloses that the solvent washing achieves extraction, where the solvent does not dissolve the polymer. However, a small amount of wax can be removed, typically less than 1 wt%. The solvent washing and extraction steps are further disclosed to be performed at the boiling point of the solvent, which is chosen to be below the softening point of the polyethylene to avoid agglomeration. The above method focuses on the removal of surface printed ink and does not mention the removal of bulk permeable contaminants, such as those previously described.

[0020] U.S. Patent Application 2009 / 0178693 discloses a method for purifying plastics. The '693 patent application also discloses a multi-step method involving pelletization to form plastic chips, surface washing with supercritical CO2, surface washing and extraction with a high boiling point solvent or solvent mixture, such as limonene and ethylene lactate, final surface washing with supercritical CO2 to remove the high boiling point solvent on the surface, and devolatilization. It is also disclosed that the plastic chip feed material is agitated with the solvent and the shape of the chips is maintained. Additionally, it is disclosed that the recovered material is maintained as chips, meaning that the method is completed at a temperature below the initial melting point of the plastic.

[0021] U.S. Patent 9,834,621 discloses a method of purifying polypropylene. The '621 patent further discloses contacting a reclaimed polypropylene at a temperature of about 80 °C to about 280 °C and a pressure of about 10 atm to about 544 atm with a first fluid solvent having a standard boiling point of less than about 70 °C to produce an extracted reclaimed polypropylene; dissolving the extracted reclaimed polypropylene in a solvent selected from the 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 14 atm to about 544 atm to produce a first solution comprising polypropylene, at least one dissolved contaminant, and at least one suspended contaminant; settling the first 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 second solution comprising polypropylene, at least one dissolved contaminant, and less of the 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 the at least one suspended contaminant; and separating the purer polypropylene from the third solution; and wherein the second fluid solvent has the same chemical composition or a different chemical composition than the first fluid solvent. The above method is well suited for removing contaminants. However, the ability to dissolve, settle, and filter plastics is very difficult and can not be feasible or practical for plastics having a high molecular weight (MW), such as those used in films and blow molded containers. Further, the above method does not mention removing surface contamination prior to extraction and dissolution, thus adding burden to such disclosed methods, especially filtration.

[0022] In summary, the known solvent-based methods to purify contaminated plastics as described above do not produce a "virgin" polymer because they do not address the problem of removing surface and bulk contaminants from plastics sufficiently and efficiently to enable use in demanding applications, particularly in films and rigid applications involving high MW plastics. Additionally, in previous methods, co-dissolution and thus cross-contamination of other polymers often occurs. If adsorbents are used, a filtration and / or centrifugation step is typically employed to remove the used adsorbents from the solution. Further, separation processes to remove the solvent such as heating, vacuum evaporation, and / or precipitation using a precipitating chemical are used to produce a polymer free of residual solvent.

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

[0024] In an embodiment of the application, a method for purifying a reclaimed polymer is disclosed. The method comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each contaminant having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of alkylphenol, bisphenol, dioxin, PCB, and phthalate; b) leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed polymer and a pressure between about atmospheric pressure and about 1,000 atm over a total residence time and a residence time for each of the leaching stages at an average removal efficiency to produce a leached polymer comprising at least one of 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 first fluid 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) 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 than at least one suspended contaminant; 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 than 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 twice-filtered polymer; g) extracting the twice-filtered polymer with a second 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 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) to produce a fifth solution comprising extracted polymer; and h) separating the extracted polymer from the fifth solution to produce a purer polymer; and wherein the second fluid solvent has the same chemical composition or a different chemical composition than the first fluid solvent.

[0025] In an embodiment of the application, a method for purifying a reclaimed polymer is disclosed. The method comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the reclaimed polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in greater than about 80% reduction in loosely bound surface contamination; c) leaching the 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed polymer and a pressure between about atmospheric pressure and about 1,000 atm over a total residence time and a residence time for each of the leaching stages at an average removal efficiency to produce a leached polymer comprising at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate, each having a concentration; wherein the average removal efficiency is greater than about 55%; d) dissolving the leached polymer in a first fluid 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) 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 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 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; 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 a twice-filtered polymer; h) stripping the fourth solution at a temperature of about 80 °C to about 280 °C and a pressure of about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) with a second fluid solvent having a normal boiling point of less than about 70°C to produce a fifth solution comprising extracted polymer; and i) separating the extracted polymer from the fifth solution to produce a more pure polymer; and wherein the second fluid solvent has the same chemical composition or a different chemical composition than the first fluid solvent. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1A Flow chart showing the main steps of one embodiment of the present invention.

[0027] Figure 1B Flow chart showing the main steps of another embodiment of the present invention.

[0028] Figure 2 Calibration curve to calculate the polyethylene content in polypropylene using the enthalpy values from DSC measurements; Figure 3A Schematic of the experimental setup used in the extraction step.

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

[0030] I. DEFINITIONS

[0031] As used herein, the term "plastic" refers to a polymer such as polyethylene (PE), PP, PET, LLDPE, LDPE, HDPE, polyethylene copolymer, ethyl vinyl acetate copolymer (EVA), ethyl vinyl alcohol copolymer (EVOH), ethylene acrylic acid copolymer (EAA), PS, PC, PVC, styrene-butadiene-styrene (SBS), PA, and the like or mixtures thereof. Such polymers are characterized by a high MW, which generally determines the melt processability and solid state mechanical properties. For the purposes of the present invention, 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 "reclaimed polymer" refers to a polymer that has been used for a prior purpose and then recovered for further processing.

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

[0034] As used herein, the term "post-consumer reclaimed" (PCR) refers to a material that occurs after the end consumer has used the material and has placed the material in a 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 that is 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 the critical point of a substance is referred to as a "supercritical fluid," which does not have 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 "precipitate" and "precipitation" are used interchangeably and refer to the tendency of particles within a suspension to separate from a liquid in response to forces acting on the particles, typically gravity.

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

[0043] As used herein, the term "dissolved contaminants" refers to unwanted or undesirable components that are at least partially bound into a 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 using mechanical and / or physical operations (e.g., passing a contaminated fluid through a filtration system). As used herein, the terms "filtration system" and "filter" are used interchangeably.

[0045] As used herein, the term "less suspended contaminants" when referring to a solution refers to a subsequent state of the solution relative to a previous state (e.g., prior to a contaminant removal step) in which the previous solution had a relatively greater amount of suspended contaminants.

[0046] As used herein, the term "comprising even less suspended contaminants" when referring to a solution refers to a subsequent state of the solution relative to a previous state (e.g., "comprising less suspended contaminants") in which 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 conditions of use. The solid medium can be crystalline, semi-crystalline, or amorphous. The solid medium can be particulate and can be supplied in different shapes (i.e., spheres, cylinders, pellets, etc.). If the solid medium is particulate, the particle size and particle size distribution of the solid medium can be defined by the mesh size used to classify the particulate medium. An example 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 non-woven fibrous mat or a woven textile.

[0048] As used herein, the term "more pure polymer solution" refers to a polymer solution having 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 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 the theory of distribution.

[0050] As used herein, the term "extracted" refers to a material having less of one or more solute species relative to the same material prior to an extraction step. As used herein, the term "extracted reclaimed polymer" refers to a reclaimed polymer having less of one or more solute species relative to the same reclaimed polymer prior to an extraction step.

[0051] As used herein, the term "pristine" refers to a material that is substantially free of contaminants, colorless, odorless, homogeneous, and similar in nature to the virgin polymer.

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

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

[0054] As used herein, any involved pressure international units (e.g., MPa) refer 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 flowing 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, as well as other solid-liquid separation equipment, is provided in the following reference: Perry, Robert H and Don W. Green. Perry's 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 equipment in which the filter media is comprised of a rigid or semi-rigid screen and one or more layers of fine solid material (e.g., diatomaceous earth, perlite, cellulose fibers, clay, activated carbon, alumina, silica, aluminum silicate, zeolite, and mixtures thereof) are deposited on the screen.

[0059] As used herein, the term "in-line feed" refers to the addition of filter aid 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 a plastic or in the bulk of a plastic. The term "chemical contaminant" refers to any undesirable chemical within the surface of a plastic or within the bulk of a plastic and includes the molecular or elemental composition of the contaminant. The terms can be used interchangeably depending on intent. For example, a paper contaminant includes cellulose. Thus, cellulose is a chemical contaminant in a paper contaminant.

[0061] As used herein, the term "contamination" refers to the sum of all contaminants and the term "chemical contamination" refers to the sum of all chemical contaminants. Chemical contaminants are grouped by class, which includes chemical contaminants having similar chemical structures. For example, As, Hg, and Cr are chemical contaminants in the "heavy metal" class. Each contaminant can have different chemical properties, such as solubility and diffusivity in a plastic, as well as target levels depending on concentration and end-use market.

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

[0063] As used herein, the term "bulk contaminant" refers to a contaminant in the bulk of a plastic. Similarly, the term "bulk chemical contaminant" refers to the molecular or elemental composition of a bulk contaminant. Typically, a bulk contaminant will have more than about 80% 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 "bulk contamination" and "bulk chemical contamination" refer to the sum of all bulk contaminants and all bulk chemical contaminants, respectively.

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

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

[0068] As used herein, the term "non-permeable contaminants" refers to chemical contaminants that are not soluble or diffusible in the plastic. Non-limiting examples of non-permeable 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 "non-permeable contamination" refers to the sum of all non-permeable contaminants. If described in molecular or elemental terms, the sum of all permeable and non-permeable contaminants is "chemical contaminants", or if described in general terms (such as cellulose with paper), simply "contaminants".

[0070] As used herein, the term "intentional contaminants" refers to contaminants that are intentionally added by the supply chain for a specific purpose to benefit the producer, retailer, or consumer, but can not be desirable in the recycled plastic. Examples include print, paper labels, adhesives for labels, pigments (such as Ti02), processing additives (such as antioxidants - AO), and the like, that are necessary for market, brand, processability, and / or end-use performance. As used herein, the term "intentional chemical contaminants" refers to intentional contaminants described by their 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 contamination described by their chemical composition.

[0071] As used herein, the surface area to volume ratio of a plastic is calculated as follows. For objects that are generally spherical, such as pellets, ground pellets, micronized pellets, and the like, the surface area to volume ratio is calculated by 3 / r where r is the mass average radius. For objects that are generally flat and thin, such as films, the surface area to volume ratio is calculated by 2 / t where t is the mass average thickness. For objects that are generally long and cylindrical, such as fibers, the surface area to volume ratio is calculated by 2 / r where r is the mass average radius. For the purposes of this 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 contaminants" refers to any contaminants that are not intentionally added. Examples include dirt and cross contamination that are not intentionally added by the producer, retailer, or consumer. As used herein, the term "unintentional chemical contaminants" refers to unintentional contaminants described by their 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 contamination described by their chemical composition.

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

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

[0075] As used herein, the term "initial melting point" refers to the peak melting point of a plastic as measured using differential scanning calorimetry (DSC) (the highest endothermic peak on the zero slope baseline). For the purposes of this invention, the terms "initial melting point," "melting point," "melting temperature," and "initial melting temperature" are used interchangeably. For amorphous materials and / or materials lacking distinct melting points, the defined temperature will be the approximate softening point of the material, which can best be characterized by the glass transition temperature. Those skilled in the art will understand the appropriateness of the 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 volume percent, and typically about 53 volume percent), isohexane (2-methylpentane, 3-methylpentane, and 2,3-dimethylbutane), and neohexane (2,2-dimethylbutane).

[0077] As used herein, the term "quantitative limit" or "LOQ" refers to the lower limit of detection for a given chemical contaminant as determined by the analytical method disclosed in Part 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 Part IX.

[0078] As used herein, the term "removal efficiency" refers to the efficiency of the process of removing a particular contaminant, calculated as 100 x (initial concentration - final concentration) / initial concentration and expressed as a percentage. In cases where the final concentration is below the LOQ, and for simplicity, the LOQ is used as the final concentration to calculate the removal efficiency, which is treated as a minimum value and designated as >. In certain cases, purer plastics will have higher levels of a contaminant than the reclaimed polymer due to 1) measurement error, 2) hot and cold spots of the contaminant in the reclaimed polymer, 3) external contamination during sampling, or 4) the purification process increasing contamination. In such cases, the removal efficiency is set to 0% to not skew the average results. If this consistently occurs in a given process, it is more likely attributable to the process and should be examined more closely, but this is typically not the case for the processes of the present invention. As used herein, the term "average removal efficiency" refers to the average of the removal efficiencies for each contaminant.

[0079] II. Recycled polymers

[0080] When first produced at a resin supplier such as Dow, Nova, ExxonMobil, etc., the polymers are primarily free of contamination (virgin plastics). However, during the life cycle of the polymers (from production to distribution, consumer use, and ultimately recycling), contamination is intentionally or unintentionally introduced.

[0081] Non-limiting examples of intentional contamination include surface printing, paper labels, adhesives for labels, pigments (such as Ti02), processing additives (such as AO), etc., which are necessary for marketing, branding, processability, and / or end-use performance. Non-limiting examples of unintentional contamination are dirt, cross-contamination, certain heavy metals, pesticides, dioxins, furans, PCBs, etc. Additionally, unintentional contamination can result from reactions involving intentional contaminants, such as oxidation of paper labels to dioxins, degradation of adhesives or printing binders, etc. Most of the latter occur during melt densification methods used in recycling processes. Furthermore, oxidation of plastics during melt processing steps, such as those used for original packaging or product manufacturing and / or recycling of the latter, will result in unintentional contamination, such as gels. Moreover, unintentional contamination can result from interactions with products. For example, packaging materials containing cleaning mixtures (e.g., limonene, surfactants, etc.), food (e.g., various organics), etc., will be potentially contaminated by such products. Finally, unintentional contamination can enter plastics during production, e.g., with reaction byproducts, unreacted monomers, etc.

[0082] It is recognized that different sources of recycled polymers 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 likelihood of contamination. On the other hand, controlled recycled polymer streams are available and exhibit lower potential risks for demanding applications. For example, if a recycled polymer stream is known to come from demanding applications, such recycled polymer streams will not contain any undesirable contaminants until dispensed to the consumer, otherwise these plastics would not be approved for these applications. Thus, preventing re-use of contamination in these same applications is primarily unintentional contamination, which must originate from external sources and enter the plastics through surface contamination. A small amount of contamination can result from reactions involving intentional contamination, such as oxidation of cellulosic materials to dioxins during melt densification.

[0083] Pre-consumer plastics generally have the lowest level of contamination due to their 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. Additionally, due to the controlled history, pre-consumer plastics tend to have low levels of unintentional contamination, preventing outside contamination. Thus, pre-consumer plastics originally intended for demanding applications would be an ideal source of recycled polymers for the same end market with minimal cleaning / purification. The latter form of pre-consumer plastics, in the form of film, is referred to as “Approved Source Post-Industrial Film” (ASPIF). The downside is that ASPIF stream supply is very limited and does not support roundness.

[0084] Post-consumer plastics are generally more contaminated than pre-consumer plastics. Considering the slightly controlled life cycle in the commercial supply chain, the post-consumer subcategory of commercial post-use has the next lowest level of contamination relative to pre-consumer recycling. Generally, commercial post-use recycled plastics will have known and controlled levels of intentional contamination, thus enabling widespread use as recycled polymers. However, known unintentional contamination is ubiquitous and this stream presents issues that hinder widespread use in demanding applications. Commercial post-use plastics derived from demanding applications will likely return to these areas after sufficient cleaning / purification. Commercial post-use plastics derived from demanding applications in the form of film are referred to as “Approved Source Post-Commercial Film” (ASPCF). To accommodate the ongoing demand for purer recycled polymers, recycling material suppliers have recently introduced commercial post-use film sources with more controlled and known histories. These new sources are referred to as high custody sources and are primarily used with commercial post-use film streams. Thus, high custody commercial post-use film sources should have reduced levels of contamination relative to general commercial post-use film sources. The downside is that these high custody sources are limited in volume and are more costly.

[0085] Considering the uncontrolled life cycle within the commercial channel, the post-consumer household post subcategory has the highest level of contamination. Such plastics have highly variable, unknown, and uncontrolled high levels of intentional and unintentional contamination. Such plastics can include plastic sources that were originally unable to be used in demanding applications. Thus, the market for this plastic source is limited and is essentially non-existent in demanding applications.

[0086] Surprisingly, the purer plastics made by the present invention can allow for more widespread use of plastics from post-industrial sources (ASPIF and non-controlled sources), post-commercial sources (ASPCF and non-controlled sources), and post-household sources in demanding applications with some limitations. Additionally, most recycling material consumers need purer materials than are currently available, and the purer plastics of the present invention meet this need for more widespread purer plastics from any source.

[0087] For the 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 it enters the recycled polymer stream), a second life plastic (used twice before it enters 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 includes virgin plastic. In embodiments of the present invention, the recycled polymer includes a film. In embodiments of the present invention, the recycled polymer is selected from the group including a film, an injection molded part, a blow molded part, a fiber, a nonwoven, a woven, a thermoformed part, an extruded strand, or a mixture thereof.

[0089] In embodiments of the present invention, the recycled polymer includes regrind / offcut / in-plant scrap plastic. In embodiments of the present invention, the recycled polymer includes a PIR polymer. In embodiments of the present invention, the recycled polymer includes a PIR polymer film. In embodiments of the present invention, the recycled polymer includes a PIR polymer nonwoven. In embodiments of the present invention, the PIR polymer film is ASPIF. In embodiments of the present invention, the recycled polymer includes a PCR polymer. In embodiments of the present invention, the recycled polymer includes a PCR polymer film. In embodiments of the present invention, the recycled polymer includes a PCR polymer nonwoven. In embodiments of the present invention, the PCR polymer film is ASPCF. In embodiments of the present invention, the recycled polymer includes a high storage PCR polymer film. In embodiments of the present invention, the recycled polymer includes a post-consumer polymer. In embodiments of the present invention, the recycled polymer includes a post-consumer polymer film. In embodiments of the present invention, the recycled polymer includes a post-consumer polymer nonwoven.

[0090] In embodiments of the present invention, the recycled polymer includes PS, co- polystyrene, PA, co-polyamide, PC, thermoplastic elastomer, styrene block copolymer, polyester, co-polyester, PVC, and copolymers of any of the foregoing and mixtures of any of the foregoing. In embodiments of the present invention, the recycled polymer includes polyolefin, polyolefin copolymer, and polyolefin polar copolymer. In embodiments of the present invention, the recycled polymer includes LDPE and LLDPE copolymer. In embodiments of the present invention, the recycled polymer includes PP. In embodiments of the present invention, the recycled polymer includes HDPE and HDPE copolymer. In embodiments of the present invention, the recycled polymer includes a film, and the film includes polyethylene and polyethylene copolymer.

[0091] In embodiments of the present application, the recycled polymer is a PCR polymer. In embodiments of the present application, the recycled polymer is a polypropylene homopolymer or a predominantly polypropylene copolymer. In embodiments of the present application, the recycled polymer is a polyethylene homopolymer or a predominantly polyethylene copolymer. In embodiments of the present application, the method for purifying a recycled polymer comprises obtaining a recycled polymer; and wherein the recycled polymer is selected from the group consisting of 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, shredded film, shredded or ground injection molded parts, shredded or ground blow molded parts, thermoformed parts, shredded nonwoven or woven, extruded strands, or agglomerated granules. In embodiments of the present application, the recycled polymer comprises pellets.

[0092] In embodiments of the present application, the recycled polymer has an average surface area to volume ratio of greater than about 1 mm -1 In embodiments of the present application, the recycled polymer has an average surface area to volume ratio of greater than about 5 mm -1 In embodiments of the present application, the recycled polymer has an average surface area to volume ratio of greater than about 20 mm -1 In embodiments of the present application, the recycled polymer has an average surface area to volume ratio of greater than about 50 mm -1 In embodiments of the present application, the recycled polymer has an average surface area to volume ratio of greater than about 50 mm

[0093] For the purposes of the present application, the recycled polymer is derived from post-consumer, post-industrial, post-commercial, and / or other special recycling waste streams. For example, a PCR polymer can be obtained from a curbside recycling stream in which an end consumer places used polymers from packaging and products into designated trash cans for collection by a trash hauler or recycler. A PCR polymer can also be derived from an in-store "recycling" program in which a consumer brings waste polymers into a store and places the waste polymers into designated collection bins. An example of a PIR polymer can be waste polymers generated during the manufacture or transport of goods or products collected by a manufacturer as unusable material (i.e., trim waste, off-spec material, start-up waste). An example of a waste polymer from a special waste stream can be a waste polymer obtained from the recycling of electronic waste (also known as "e-waste"). Another example of a waste polymer from a special waste stream can be a waste polymer obtained from the recycling of automobiles. Another example of a waste polymer from a special waste stream can be a waste polymer obtained from the recycling of used carpet and textiles.

[0094] For the purposes of the present invention, a reclaimed polymer is a homogeneous composition of a single polymer or a mixture of several different polymer compositions. Non-limiting examples of reclaimed polymer compositions are homopolymers and copolymers of polyolefins such as polyethylene and isotactic polypropylene; polyesters such as poly(ethylene 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 rubbers; and other dissolvable polymers as can be apparent to one of ordinary skill in the art.

[0095] The reclaimed polymer can also contain various pigments, dyes, processing aids, stabilizing additives, fillers, and other performance additives that are added to the polymer during the original polymer's polymerization or conversion into the final form of the article. Non-limiting examples of pigments are organic pigments such as copper phthalocyanine, inorganic pigments such as titanium dioxide, and other pigments as can be apparent to one of ordinary skill in the art. One non-limiting example of an organic dye is Basic Yellow 51. Non-limiting examples of processing aids are antistatic agents such as glycerol 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 fibers.

[0096] III. Contaminants

[0097] Contaminants can generally be divided into two categories of migration: 1) permeable; and 2) impermeable. Permeable contaminants have solubility and diffusivity in the reclaimed polymer to allow migration into, through, and out of the polymer due to a chemical potential gradient. In other words, the group of permeable contaminants and permeable contamination is mobile. By impermeable is meant that the contaminant does not have sufficient solubility and diffusivity to move significantly into, through, and out of the polymer. In other words, the impermeable contamination, represented by the sum of all impermeable contaminants, is essentially fixed. Thus, wherever the impermeable contaminants are first deposited, such contamination will remain at that location until physically removed, convectively transferred, or placed in contact with a different material to which the contaminant is permeable.

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

[0099] The LOQs for various contaminants can differ by several orders of magnitude using the analytical methods disclosed in Section IX. 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 la-li, several film sources were broadly categorized for chemical contamination using the analytical methods disclosed in Section IX, including three ASPIF sources, three high- storage post-consumer commercial film sources, three post-consumer commercial film sources, and one post- consumer household film source. To simplify the presentation of the chemical contamination results, the concentration data are shown in LOQ rather than absolute weight fraction. For example, if the contaminant concentration is 10 ppm and the LOQ is 1 ppm, then the concentration will be 10 x LOQ or simply 10 is shown in the data table. In addition, "dnt" stands for "not tested."

[0101] Tables la-li

[0102] Chemical Contamination of ASPIF, High-Storage Post-Consumer Commercial (HCPC), Post-Consumer Commercial (PC), and Post-Consumer Household (PH) Film Sources

[0103] Table la

[0104] Chemical Contamination - Pesticides

[0105] Table lb

[0106] Chemical Contamination - Alkylphenol Ethoxylates

[0107] Table lc

[0108] Chemical Contaminants - Alkylphenols

[0109] Table 1d

[0110] Chemical Contaminants - Bisphenols

[0111] Table 1e

[0112] Chemical Contaminants - Dioxins, dioxin-like furans and PCBs

[0113] Table 1f

[0114] Chemical Contaminants - Metals

[0115] Table 1g

[0116] Chemical Contaminants - Organotins

[0117] Table 1h

[0118] Chemical Contaminants - Phthalates

[0119] Table 1i

[0120] Chemical Contaminants - PAHs

[0121] The ASPIF sources tested were largely free of detectable levels of chemical contaminants, with the exception of alkylphenols and heavy metals, and low levels of organotins and PAHs. The chemical contamination results for these ASPIF sources were used as a guide to represent the levels of chemical contamination for these controlled end markets, and demonstrated that heavy metals, which in any case have low risk of transfer, are ubiquitous in all film sources. Therefore, heavy metals were not included in the ongoing analysis within this application. The high-stores commercial post-consumer film sources tested were largely free of pesticides and alkylphenol ethoxylates, but contained detectable levels of alkylphenols, bisphenols, dioxins / furans / PCBs and PAHs, and low levels of phthalates. Each category evaluated for the commercial post-consumer film sources tested was severely contaminated; for example, dioxins were typically up to 40x LOQ, but for one source, dioxins were up to 200x LOQ. The post-consumer household sources tested were the most heavily contaminated; for example, dioxins were up to 300x LOQ, and PCBs were up to 180x LOQ.

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

[0123] In embodiments of the application, the chemical contaminants in the recycled polymer include at least one chemical contaminant, and the chemical contaminant is selected from the group comprising: an insecticide, an alkylphenol, an alkylphenol ethoxylate, a bisphenol, a dioxin, a furan, a PCB, a phthalate, a PAH, or a mixture thereof.

[0124] In embodiments of the application, the insecticide includes piperonyl butoxide, BAC, DEET, and DDAC. In embodiments of the application, the alkylphenol ethoxylate includes isononylphenol monoethoxylate, isononylphenol diethoxylate, isononylphenol triethoxylate, and isononylphenol tetraethoxylate. In embodiments of the application, the alkylphenol includes isononylphenol, 4-tert-butylphenol, and 4-tert-amylphenol. In embodiments of the application, the bisphenol includes bisphenol A. In embodiments of the application, the dioxin includes 1.2.3.6.7.8-HxCDD, 1.2.3.4.6.7.8-HpCDD, and OCDD. In embodiments of the application, the furan includes OCDF. In embodiments of the application, the PCB includes PCB 77, PCB 81, PCB 126, PCB 105, PCB 114, PCB 118, PCB 123, PCB 156, and PCB 167. In embodiments of the application, the phthalate includes di-2-propylheptyl phthalate, diisobutyl phthalate, dibutyl phthalate, di-l-ethylhexyl phthalate, and diisononyl phthalate. In embodiments of the application, the PAH includes acenaphthene, acenaphthylene, anthracene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[e]pyrene, benzo[g.h.i]perylene, chrysene, cyclopenta[c.d]pyrene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene. In embodiments of the application, the organotin includes monobutyl tin, dibutyl tin, and dioctyl tin.

[0125] In embodiments of the invention, the contaminants in the reclaimed polymer can include 4-tert-pentylphenol. In embodiments of the invention, the contaminants in the reclaimed polymer can include bisphenol A. In embodiments of the invention, the contaminants in the reclaimed polymer can include OCDD. In embodiments of the invention, the contaminants in the reclaimed polymer can include PCB 118. In embodiments of the invention, the contaminants in the reclaimed polymer can include di-2-ethylhexyl phthalate.

[0126] To simplify the presentation of the results of the purification of the objectives and related examples of the invention, the number of chemicals presented for each chemical class is limited to the representative chemicals described above for each chemical class as shown in Table 2, along with the associated LOQ and corresponding levels tested for the ASPIF source. Although more extensive and complete chemical analysis was completed for all objectives of the invention, only selected chemicals are consistently shown. This simplification does not affect or alter the invention or conclusions drawn therefrom. The selected chemicals are sufficiently and consistently representative of the broader classes with respect to 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 respective LOQ; wherein the reclaimed polymer has at least one detectable pesticide. In embodiments of the invention, the concentration of bisphenol A in the purer plastic is below its respective LOQ; wherein the reclaimed polymer has at least detectable bisphenol A. In embodiments of the invention, the concentration of each dioxin in the purer plastic is below its respective LOQ; wherein the reclaimed polymer has at least one detectable dioxin. In embodiments of the invention, the concentration of each PCB in the purer plastic is below its respective LOQ; wherein the reclaimed polymer has at least one detectable PCB. In embodiments of the invention, the concentration of each phthalate in the purer plastic is below its respective LOQ; wherein the reclaimed polymer has at least one detectable phthalate.

[0130] In embodiments of the 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 embodiments of the invention, the removal efficiency of piperonyl butoxide contaminants is greater than 55% and the concentration of piperonyl butoxide in the recycled polymer is at least 10 ppb. In embodiments of the invention, the removal efficiency of piperonyl butoxide contaminants is greater than 85%. and the concentration of piperonyl butoxide in the recycled polymer is greater than about 10 ppb.

[0132] In embodiments of the invention, the removal efficiency of 4-tert-amylphenol contaminants is greater than 55% and the concentration of 4-tert-amylphenol in the recycled polymer is at least 5 ppb. In embodiments of the invention, the removal efficiency of 4-tert-amylphenol contaminants is greater than 85% and the concentration of 4-tert-amylphenol in the recycled polymer is at least 5 ppb.

[0133] In embodiments of the 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 embodiments of the 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 embodiments of the 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 embodiments of the 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 embodiments of the application, the removal efficiency of OCDF contaminants is greater than 55% and the concentration of the OCDF in the recycled polymer is greater than about 0.2 ppt. In embodiments of the application, the removal efficiency of OCDF contaminants is greater than 93% and the concentration of the OCDF in the recycled polymer is greater than about 0.2 ppt.

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

[0137] In embodiments of the application, the removal efficiency of di-2-ethylhexyl phthalate contaminants is greater than 55% and the concentration of the di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb. In embodiments of the application, the removal efficiency of di-2-ethylhexyl phthalate contaminants is greater than 78% and the concentration of the di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb.

[0138] In embodiments of the application, the removal efficiency of phenanthrene contaminants is greater than 55% and the concentration of the phenanthrene in the recycled polymer is at least 1 ppb. In embodiments of the application, the removal efficiency of phenanthrene contaminants 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 or throughout the bulk of the plastic. Surface contamination is most conveniently and easily removed by surface cleaning techniques 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 techniques. If the surface contamination is impermeable in the plastic, such contamination will not diffuse throughout the bulk and will be reduced by simple surface cleaning methods such as aqueous washing. Bulk contamination of the permeable or impermeable type is typically not effectively removed by simple surface purification methods such as aqueous washing. Bulk contamination of the impermeable type (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 throughout the life cycle of the plastic until recycling. If the contamination is permeable, the contamination will migrate into the bulk plastic over time. Thus, in the absence of a contamination or purification event, the contamination will remain substantially constant, but the balance of surface to bulk contamination will change over time but will approach equilibrium over long periods of time. Typically, loosely bound surface contamination such as dirt can be 0.01 wt% to about 0.1 wt%; whereas chemical contamination, especially the chemical contaminants to which the present invention is directed, will be at ppm, ppb, or even ppt levels.

[0141] Permeable and impermeable contamination represent different challenges in demanding applications. For example, permeable contamination, whether in the bulk plastic or on the surface of the plastic, will have the potential to migrate to uncontaminated materials such as products or human skin. Thus, if a package contains a permeable contaminant, such contaminant will have the potential to migrate into the product and render it unsuitable for these demanding end markets. However, if the contaminant is impermeable and in the bulk of the plastic, it will have low ability to transfer to the product or the user's skin unless the bulk plastic is broken down or ingested. Thus, a package can potentially use this contaminated plastic material and there is no 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 contaminant will have the ability to transfer to the product or the skin through direct contact transfer and would be unacceptable for use in these demanding applications. 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. For example, if a surface contaminated film is melt densified or melt extruded into a different shape such as a pellet, all of the original surface contamination will become bulk contamination, whether it was impermeable or not, and such bulk contamination will be more difficult to remove with purification methods. Melt densification is common in the recycling industry. It is also common in the recycling industry to shred incoming plastic. The latter method typically does not convert surface contamination to bulk contamination. Ideally, a surface purification method such as surface washing occurs on the original contaminated surface such as a shredded film where all of the original surface area is accessible by the surface washing fluid.

[0142] In general, it is difficult to distinguish surface contamination from bulk contamination using analytical methods. Most analytical methods for permeable chemical contaminants involve solvent extraction of the contaminant from the plastic over an extended period of time greater than 6 h 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 contaminants. The efficiency of purification methods to remove surface contamination can be estimated from the difference in contamination before and after a surface cleaning step, but this assumes that bulk contamination is not significantly affected, which can be the case with surface washing with aqueous surface washing fluids discussed in the present invention. A more precise way to quantify surface contamination is by washing, followed by solvent extraction of the contaminant at different times, and then extrapolating the amount of contaminant removed at infinitesimal time, which will approximate the amount of surface contamination. However, this method is time consuming and costly, especially for contaminants that are generally difficult to measure. Furthermore, since the balance of surface and bulk contaminants is dynamic, it is difficult to quantify 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 a surface washing step.

[0143] In general, bulk contamination will not be significantly removed by simple aqueous surface washing. Diffusion mechanisms through a chemical potential gradient can remove permeable bulk contamination. Although bulk-impermeable contamination is essentially captured by the bulk polymer, and methods to release the captured contaminant include melt convection, melt filtration, and dissolution / disintegration of the plastic.

[0144] 1. In embodiments of the invention, a method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each contaminant having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of alkylphenol, bisphenol, dioxin, PCB, and phthalate. In embodiments of the invention, a method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each contaminant having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. In embodiments of the invention, the alkylphenol, bisphenol, dioxin, PCB, and phthalate include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate.

[0145] IV. Surface Purification

[0146] Surface purification reduces surface contamination. One such method is surface washing with a surface washing fluid, which is typically water-based. Surface washing is desirably completed prior to any melt mixing or melt densification to allow effective cleaning of the original surface contamination. Reclaimed polymers are often in the form of pellets, loose or compacted films, loose or compacted flexible packaging, loose or compacted rigid materials, loose or compacted nonwovens, etc., which are difficult to surface wash due to the overall size being too large. Therefore, a pelletizing or chopping step is preferred prior to surface washing. For films, it is particularly important to exfoliate all available film layers so that the washing fluid can access all original surface contamination. Therefore, the size reduction step prior to surface washing should not significantly reduce the average surface area to volume ratio of the reclaimed source, or exchange with new surface area.

[0147] In embodiments of the invention, the surface washing of the reclaimed polymer is performed after a chopping or pelletizing step. Surface washing will include significant mechanical agitation to loosen surface dirt and other contaminants, allowing physical removal and transfer into the washing fluid, where the dirt or other contaminants can or can not be soluble.

[0148] As used herein, in the surface washing step, the reclaimed plastic in its original soiled form (except without the possibility of eliminating more than 25% of the volume size reduction of the original surface) is contacted with an aqueous solution under mechanical agitation and then separated from the aqueous medium which now contains such soiling. Such a surface washing step will typically remove the majority of loosely bound surface soiling, including but not limited to dirt, wood, loosely bound paper, and some surface chemical soiling. Typical levels of loosely bound surface soiling from a film-based recycle source are between about 0.01 wt% and 0.1 wt%. In embodiments of the present invention, the surface washing will remove greater than about 80% of the loosely bound surface soiling.

[0149] Surface washing technologies are widely available on the market. One technology comes from Lindner (Lindner Washtech GmbH, Haldenfeld 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 possibility of applying caustic to remove the binder, followed by drying and pelletization. Another technology comes 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 pelletization. Another technology comes from Sorema (Sorema S.r.l., Anzano del Parco, Italy). This technology is described in detail elsewhere (http: / / sorema.it / en_US / applications / washing-line / ) but involves similar aqueous operations relative to Lindner and Herbold. Finally, another technology comes from Cadel, 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 with specific surfactants, followed by water rinsing and drying. This process can optionally include densification, melt filtration, devolatilization, and pelletization after the surface washing. This method differs from other known methods in that it requires removal of surface printing inks. This would be advantageous due to the reduced burden of removing chemical contaminants through the overall purification method of the present invention.

[0150] Three prior art surface washing technologies were evaluated for average removal efficiency of five selected contaminants (Comparative Examples 1, 2, and 3). Each surface washing technology was evaluated using different reclaimed films with different levels of contamination. Overall, the prior art surface washing technologies were not able to sufficiently purify the reclaimed polymers for controlled end markets. For the selected contaminants, the commercial technologies were not able to reduce to levels close to the LOQ, despite the lower initial contamination of the respective reclaimed polymers. In addition, the average removal efficiency for 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, di-2-ethylhexyl phthalate was less than about 55%.

[0151] In embodiments of the present application, the reclaimed polymer is surface washed in a surface washing step prior to the leaching step in a non-densified state to produce a surface washed polymer; wherein the surface washing results in greater than about 80% reduction of loosely bound surface contamination. In embodiments of the present application, the reclaimed polymer is surface washed in a surface washing step prior to the leaching step in a non-densified state to produce a surface washed polymer; wherein the surface washing results in greater than about 80% reduction of loosely bound surface contamination; wherein the reclaimed polymer has an average surface area to volume ratio of greater than about 1 mm -1 prior to the surface washing; wherein the surface washing process is a deinking type; and wherein the deinking process results in a delta E change of less than about 10% between the deinked polymer and the reclaimed polymer without surface printing ink.

[0152] V. Melt Densification

[0153] Provided that the surface purification temperature is below the initial melting point of the reclaimed polymer, the plastic exiting the surface purification step will generally have a similar geometry and similar average surface area to volume ratio as the entering reclaimed polymer. For example, if the reclaimed plastic is a loose film, the film will exit the surface purification as a shredded film after shredding and surface washing at a temperature below the initial melting point of the reclaimed polymer. Because such loose plastics are difficult to feed into certain bulk purification methods such as liquid-liquid extraction, it can be desirable to melt-densify such plastics prior to bulk purification.

[0154] A preferred method of melt densification is melt extrusion. Melt extrusion not only densifies the plastic, but it can provide the pressure needed for downstream bulk 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 can be needed to increase the pressure needed for downstream bulk purification steps. Other densification methods are known in the art, including spin disk and spin drum densifiers, which operate at lower temperatures relative to melt-based methods.

[0155] In embodiments of the application, the melt densification comprises melt extrusion. In embodiments of the application, the melt extrusion comprises melt filtration. In embodiments of the application, the melt extrusion comprises melt devolatilization. In embodiments of the application, the melt extrusion comprises melt pumping. In embodiments of the application, the melt densification comprises melt extrusion, melt filtration, melt devolatilization, and melt pumping.

[0156] VI. Immersion leaching

[0157] Surprisingly, it has been found that the combination of an immersion leaching step (disclosed in this section VI) or a combination of surface purification and immersion leaching steps (disclosed in section VII) with a purification process (disclosed in section VIII) produces much purer polymers from the reclaimed polymers with much higher efficiency than when the purification process is used alone. While not wishing to be bound by any theory, the applicants hypothesize that the removal of contaminants in the leaching step makes it more efficient to remove the 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 applicants believe that in the absence of the leaching step or the surface purification and leaching steps, the surface contaminants of the reclaimed polymers become bulk contaminants and thus they become more 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 bulk contaminants of large geometric size and remove some volatile bulk contaminants, but will be largely ineffective for most bulk contaminants, particularly to the levels desired.

[0159] One commercial technology for bulk purification is the InterRema Refresher from EREMA ™ (EREMA Group, Ansfelden, Austria; https: / / www.erema.com / en / refresher / ). This technology is described in detail elsewhere, but essentially comprises devolatilization of particulate material at temperatures below the initial melting point of the plastic for extended periods of time to remove volatile organics. Most of the chemical contaminants associated with reclaimed polymers and discussed in the previous sections are highly non-volatile, with standard boiling points typically above 200°C. Thus, this type of devolatilization technology will have limited ability to remove most of the chemical contaminants mentioned in this application.

[0160] Other techniques based on devolatilization are common. These can be standalone unit operations, or combined with other operations including extrusion and melt filtration. Those utilizing sub-ambient pressure above the molten stream of the recycled plastic are common. One overall purification technique involving devolatilization was analyzed for its purification capabilities. This technique involves a slightly elevated temperature but below the initial melting point of the plastic, a long residence time (greater than about 2 h), and continuous reflux of purified air to provide devolatilization (Comparative Example 4). The commercial devolatilization technique was not able to sufficiently remove the selected contaminants. For example, the selected contaminants were still well above the LOQ, and the average removal efficiency was about 41%.

[0161] Extraction is a preferred overall purification method. Extraction involves the use of a purification solvent to remove overall permeable contaminants by creating a chemical potential gradient between the recycled polymer and the solvent. The rate of permeable chemical contaminant removal will depend on the diffusion rate and solubility of the contaminant in the plastic under the conditions created in the process. For high MW plastics, the diffusion rate of macromolecules indicative of chemical contaminants is very low, especially in the solid state of the plastic. In addition, solubility can be limited due to the high MW of the recycled polymer and lack of enthalpic mixing. Thus, the time required to remove permeable contaminants by diffusion mechanisms can be quite long and is not conducive to an economically viable process on a commercial scale. Methods to address these time scale limitations include 1) increasing the diffusion rate by elevated temperature and / or increasing plastic relaxation by solvent swelling, 2) decreasing the diffusion path length by increasing the average surface area to volume ratio of the recycled polymer exposed to the solvent, and 3) increasing convective transport of the contaminant across the plastic / solvent interface by increasing the solubility of the contaminant in the solvent, increasing the partitioning of the contaminant in the solvent relative to the plastic; increasing convection across the plastic / solvent interface, and increasing the solvent tank relative to the plastic tank. The solubility of the overall purification solvent in the plastic can be increased by operating the extraction at high pressure, particularly at, near, or above the critical pressure.

[0162] It is important that the extraction process be scalable to large volumes at low cost. Thus, the time required for extraction should be short to allow for this scalability. In embodiments of the invention, the total time for extraction is less than about 6 h, preferably less than about 4 h, more preferably less than about 2 h, and even more preferably less than about 1 h. If extraction is done in stages, the time for each stage can 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 referred to as a liquid-liquid extraction. Extraction performed below the initial melting point of the recycled polymer is referred to as a leaching extraction, or simply a leaching process. The extraction solvent used in a leaching extraction is referred to as a leaching solvent.

[0164] In the immersion leaching step of the present invention, the reclaimed polymer is contacted with an excess of solvent at each stage and at each time period of the step. Such a leaching process is referred to as an immersion leaching process. For the purposes of the present invention, "immersion leaching" and "leaching" are used interchangeably. Additionally, 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 leaching solvent is preferably equal to or greater than about 5: 1 to the mass of reclaimed polymer exposed to the solvent at each time point and at each stage of the process. In certain leaching steps, the solvent is rapidly stirred such that the reclaimed polymer is suspended in the solvent even when the density of the reclaimed polymer is greater than the density of the solvent. Such leaching steps ensure full contact between the surface of the reclaimed polymer and the leaching solvent and reduce the mass transfer resistance within the solvent boundary layer around the surface of the reclaimed polymer due to convective motion. In addition to stirring, a similar reduction in the boundary layer can be achieved in the immersion leaching step by allowing the reclaimed polymer to settle through the solvent with a density gradient. Examples of immersion leaching steps include continuous (also referred to as continuous stirred tank reactor - CSTR), semi-continuous, and batch types of stirred tanks. Additional examples of immersion leaching steps include settling tanks in which the reclaimed polymer is allowed to settle out or through solvent filled in a tank or other vessel. Applicants have found that for the immersion leaching step of the present invention, the leaching solvent to reclaimed polymer mass ratio should preferably be greater than about 5: 1 at any time point and at any stage, more preferably greater than 10: 1 per stage, and most preferably greater than about 20: 1 to enable the reclaimed polymer to be fully dispersed and exfoliated within the leaching solvent.

[0166] In embodiments of the present invention, the immersion leaching step is carried out in a stirred tank. In embodiments of the present invention, the immersion leaching step is carried out in a CSTR. In embodiments of the present invention, the immersion leaching step is carried out in a batch stirred tank. For all stirred tank processes, the ability to expose the surface area of the reclaimed polymer to the leaching solvent is critical. The design of the reactor should include the potential use of vigorous mechanical stirring and a large number of baffles.

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

[0168] In embodiments of the present application, the submerged extraction step is operated at a temperature below the initial melting point of the reclaimed polymer and at a pressure of about atmospheric pressure and about 1,000 atm. In embodiments of the present application, the submerged extraction step is operated at a temperature below the initial melting point of the reclaimed polymer and at a pressure of about atmospheric pressure. In embodiments of the present application, the submerged extraction step is operated at a temperature below the initial melting point of the reclaimed polymer and at a pressure of about atmospheric pressure and about 1,000 atm, using an extraction solvent in multiple extraction stages over the total residence time of the submerged extraction step and the residence time of each of the extraction stages.

[0169] In embodiments of the present application, the extraction solvent is at or near the standard boiling point. For polyolefin reclaimed polymers, preferred extraction solvents for submerged extraction have a boiling point in the range of 20°C to 90°C. Non-limiting examples of such solvents are tetrahydrofuran (THF), diethyl ether, hexane, acetone, ethanol, methanol, propanol, isopropanol, methyl ethyl ketone (MEK), and ethyl acetate. In embodiments of the present application, the extraction solvent has a standard boiling point between 20°C and 90°C. In embodiments of the present application, the extraction solvent has a standard boiling point between 20°C and 90°C and the extraction temperature is at or near the boiling point. In embodiments of the present application, the extraction solvent has a standard boiling point between 20°C and 90°C, the extraction temperature is at or near the boiling point, and the extraction pressure is about atmospheric pressure. For such extraction solvents, the pressure can also be above atmospheric pressure. In embodiments of the present application, the extraction solvent has a standard boiling point between 20°C and 90°C and the extraction pressure is between above atmospheric pressure and about 1,000 atm. The extraction solvent can also have a boiling point above the extraction temperature. In embodiments of the present application, the extraction solvent has a standard boiling point above the extraction temperature. In embodiments of the present application, the extraction solvent is ethyl acetate; the extraction temperature is between about 20°C and about 120°C; and the extraction pressure is between about atmospheric pressure and about 1,000 atm. In embodiments of the present application, the extraction temperature is between about 20°C and about 90°C and the extraction pressure is between about atmospheric pressure and about 1,000 atm, the extraction solvent is ethyl acetate, the total residence time of the extraction step is less than about 360 min, and the average removal efficiency is about 55%. In embodiments of the present application, the extraction solvent is hexane; the extraction temperature is between about 20°C and about 120°C; and the extraction pressure is between about atmospheric pressure and about 1,000 atm.

[0170] Due to the elevated submersion leaching pressure, leaching solvents with a standard boiling point below the leaching temperature are also preferred. In embodiments of the present application, the leaching solvent has a standard boiling point below the leaching temperature. In embodiments of the present application, the leaching solvent is propane. In embodiments of the present application, 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 embodiments of the present application, the leaching solvent is dimethyl ether (DME). In embodiments of the present application, 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 with a standard boiling point below the leaching temperature and a critical temperature below the leaching temperature are also preferred. In embodiments of the present application, the leaching solvent has a standard boiling point below the leaching temperature and a critical temperature below the leaching temperature. In embodiments of the present application, the leaching solvent is ethane. In embodiments of the present application, the leaching solvent is critical or supercritical ethane. In embodiments of the present application, the leaching solvent is ethane; the leaching temperature is between about 31 °C and about 120 °C; and the leaching pressure is between about 40 atm and about 1,000 atm. In embodiments of the present application, the leaching solvent is CO2. In embodiments of the present application, the leaching solvent is CO2; the leaching temperature is between about 31 °C and about 120 °C; and the leaching pressure is between about 68 atm and about 1,000 atm. In embodiments of the present application, the leaching solvent is CO2 with less than 5 wt% water.

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

[0173] Preferred leaching solvents include solvents with a higher affinity for chemical contaminants than for reclaimed polymer. Solvents with a high affinity for chemical contaminants of interest in reclaimed polyolefins include, but are not limited to, diethyl ether, MEK, ethyl acetate, THF, acetone, dichloromethane, and methanol, relative to their affinity for polyolefins. Other oxygenated and polar hydrocarbon solvents can have similar desired affinities. Solvents lacking such properties can still be used, but can require a higher solvent to polymer ratio. Preferably, the solvent should not significantly dissolve the reclaimed polymer at the temperature and pressure of the submersion leaching step (less than about 5 wt% dissolvable).

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

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

[0176] The submerged leaching process can be carried out in stages and in combination with other types of additional leaching steps not discussed in this disclosure. The same is true for liquid-liquid extraction processes. Furthermore, liquid-liquid extraction processes can be combined with submerged leaching steps at various stages to form a given purification process. In embodiments of the present application, the number of leaching stages is more than one. In embodiments of the present application, the number of leaching stages is between about 1 and about 50. In embodiments of the present application, the number of leaching stages is between about 2 and about 30. In embodiments of the present application, the number of leaching stages is between about 5 and about 20. In embodiments of the present application, the number of liquid-liquid stages is more than one. In embodiments of the present application, the number of leaching stages is more than one. In embodiments of the present application, 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. The efficiency can be improved by having multiple stirred tank reactors in series, where the reclaimed polymer from stage 1 is primarily separated from the stage 1 leaching solvent, and the stage 1 plastic is used in stage 2 with fresh leaching solvent. This is repeated for each additional stage. This method improves the removal efficiency at the expense of additional reactors and complexity, but maintains the 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 method can be used.

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

[0179] Generally, Applicants have found that the total fresh or refreshed leaching solvent to regenerated polymer mass ratio is preferably greater than about 5: 1. In embodiments of the present application, the total fresh or refreshed leaching solvent to regenerated polymer mass ratio is greater than about 10: 1. In embodiments of the present application, the total fresh or refreshed leaching solvent to regenerated polymer mass ratio is greater than about 15: 1. In embodiments of the present application, the total fresh or refreshed leaching solvent to regenerated polymer mass ratio is greater than about 20: 1. In embodiments of the present application, the total fresh or refreshed leaching solvent to regenerated polymer mass ratio is greater than about 30: 1 and less than about 100: 1.

[0180] If the immersion leaching is accomplished in stepwise or continuous stages, the leaching solvent to regenerated polymer ratio for each stage can be lower than this specified range (but still greater than about 5: 1 minimum per stage), but the total solvent used in the total regenerated polymer should be within this range represented by the sum of the solvent used in all stages. In addition, the contaminated solvent from any stage can be used "as is" as the solvent for another stage. The contaminated solvent at any point in the process can be refreshed by known distillation, filtration, ion exchange, etc. methods or combinations.

[0181] Another important kinetic driver is the average surface area to volume ratio of the regenerated polymer within the leaching solvent and exposed to the leaching solvent. Generally, the time required to extract a chemical contaminant from a 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 geometry of the regenerated polymer and the ability of the leaching solvent to access the surface area. Therefore, a higher average surface area to volume ratio will result in a reduced diffusion path length and faster diffusion kinetics. For the immersion leaching step, a high average surface area to volume ratio is a key parameter for fast and efficient removal of 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 can contain a small amount of leaching solvent in physisorbed or bulk adsorbed form. The concentration of leaching solvent in the leached polymer can be reduced by devolatilization techniques. In embodiments of the invention, the leached polymer is devolatilized to a content of less than 1 wt% leaching solvent in the reclaimed polymer.

[0188] Stirred tank reactors operated at the boiling point of the leaching solvent provide an improvement over existing processes. For example (Examples 1, 2, 3, and 4 and Tables 7, 8, 9, and 10), the immersion leaching step conducted with ethyl acetate or THF provided removal efficiencies of greater than about 88% of selected contaminants.

[0189] In embodiments of the invention, the leaching solvent is ethyl acetate. In embodiments of the invention, the leaching solvent is ethyl acetate and the leaching pressure is about atmospheric pressure. In embodiments of the invention (Example 1 and Table 7), the immersion leaching step is conducted 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. In embodiments of the invention, the immersion leaching step is conducted in a stirred tank, the leaching temperature is about 77.1 °C, the leaching pressure is about atmospheric pressure, the leaching solvent comprises ethyl acetate; wherein the reclaimed polymer has a surface area to volume ratio of about 80 mm -1 ; the number of leaching stages is 2, the mass ratio of ethyl acetate to reclaimed polymer per stage is about 18: 1, the immersion leaching residence time per stage is about 50 min, the total mass ratio of ethyl acetate to reclaimed polymer is about 36: 1, the total residence time is about 100 min; and the average of the reductions in the concentrations of 4-tert-amyphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate is about 89%.

[0190] In embodiments of the invention (Example 2 and Table 8), the immersion leaching step is conducted in a stirred tank, the leaching temperature is about 77.1 °C, the leaching pressure is about atmospheric pressure, the leaching solvent comprises ethyl acetate; wherein the reclaimed polymer has a surface area to volume ratio of about 80 mm -1 ; the number of leaching stages is 2, the mass ratio of ethyl acetate to reclaimed polymer per stage is about 18: 1, the immersion leaching residence time per stage is about 30 min, the total mass ratio of ethyl acetate to reclaimed polymer is about 36: 1, the total residence time is about 60 min; and the average of the reductions in the concentrations of 4-tert-amyphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate is about 89%.

[0191] In embodiments of the invention, the leaching solvent is THF. In embodiments of the invention, the leaching solvent is THF and the leaching pressure is about atmospheric pressure. In embodiments of the invention, the submersion leaching is conducted 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 embodiments of the invention (Example 3 and Table 9), the submersion leaching step is conducted 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, the reclaimed polymer has a surface area to volume ratio of about 80 mm -1 , the THF to reclaimed polymer ratio is about 18: 1 per stage, the residence time for each leaching stage is about 50 min, the total mass ratio of THF to reclaimed polymer is about 36: 1, the total residence time for the submersion leaching step is about 100 min; and the average reduction in concentration of 4-tert- amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate is about 90%.

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

[0193] After the submersion leaching step, the leached polymer can be physically wetted with residual leaching solvent and can contain a small amount of absorbed leaching solvent. As discussed previously, there are many methods for recovering the leached polymer and leaching solvent independent of 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 embodiments of the invention, the leached polymer is processed to reduce the leaching solvent in the reclaimed polymer to less than about 1 wt%. The contaminated leaching solvent can be cleaned up with known distillation methods, ion exchange, filtration, etc. The resulting devolatilized reclaimed polymer can be used as is or can be further processed into other forms by various methods, including pellets.

[0194] In embodiments of the present application, the total residence time of the leaching step is less than about 600 min. In embodiments of the present application, the total residence time of the leaching step is less than about 480 min. In embodiments of the present application, the total residence time of the leaching step is less than about 360 min. In embodiments of the present application, the total residence time of the leaching step is less than about 180 min. In embodiments of the present application, the total residence time of the leaching step is less than about 60 min.

[0195] In embodiments of the present application, the residence time of each of the leaching steps is less than about 180 min. In embodiments of the present application, the residence time of each of the leaching steps is less than about 90 min. In embodiments of the present application, the residence time of each of the leaching steps is less than about 60 min. In embodiments of the present application, the residence time of each of the leaching steps is less than about 30 min. In embodiments of the present application, the residence time of each of the leaching steps is about 20 min.

[0196] In embodiments of the present application, the method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each having a concentration; and wherein the contaminants of the reclaimed polymer comprise at least one of alkylphenol, bisphenol, dioxin, PCB, and phthalate ester; and b) leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate ester from the reclaimed polymer in multiple leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed 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 of each of the leaching stages, to produce a leached polymer comprising at least one of alkylphenol, bisphenol, dioxin, PCB, or phthalate ester, each having a concentration; and wherein the average removal efficiency is greater than about 55%.

[0197] In embodiments of the present application, wherein the leaching step is performed in a continuous stirred tank reactor (CSTR); wherein the reclaimed polymer is surface washed in a non-densification state prior to dissolution in a surface washing process; wherein the surface washing process results in a greater than about 80% reduction in loosely bound surface contamination; wherein the reclaimed polymer has a greater than about 1 mm -1an average removal efficiency; wherein the surface washing process is of the deinking type; wherein the deinking process results in a change in ΔE between the deinked polymer and the reclaimed polymer without surface printing ink of less than about 10%; 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 near atmospheric pressure; wherein the residence time for each of the leaching stages is about 20 min; wherein the reclaimed 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 embodiments of the present application, a method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each contaminant having a concentration; and wherein the reclaimed polymer contaminants include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; and b) leaching the 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the reclaimed polymer in multiple leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed polymer and a pressure between about atmospheric pressure and about 1,000 atm for a total residence time and a residence time for each of the leaching stages with an average removal efficiency to produce a leached polymer comprising at least one of 4-tert-pentylphenol, 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 submersion leaching steps

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

[0201] The preferred method of surface washing has been discussed in the surface purification section. An even more preferred method of surface washing is the de-inking 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 inks. This method is also quite effective at removing paper labels as precursors to chemical contaminants. In this method, a reclaimed polymer with an exposed virgin surface area is fed into a multi-step aqueous washing process where surface contaminants including surface printed inks, 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 de-inking method is any surface washing method where the method removes enough surface print to produce a delta E difference between the de-inked reclaimed polymer and an unprinted reclaimed polymer of less than about 10% (delta E measured using Method 3 in Section IX).

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

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

[0204] In embodiments of the present application, the submerged leaching step is performed after a surface washing. In embodiments of the present application, the submerged leaching step is performed after a surface washing process; and wherein the reclaimed polymer is not densified prior to the surface washing process. In embodiments of the present application, the submerged leaching is performed after a surface washing process; wherein the reclaimed polymer is not densified prior to the surface washing process; and wherein the surface washed reclaimed polymer can be densified prior to the submerged leaching step.

[0205] In embodiments of the present application, 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 reclaimed polymer has been partially purified using a surface washing process.

[0206] In embodiments of the present application (Example 4 and Table 10), the surface washing process involves deinking commercially available by Cadel; the deinking results in a delta E change of less than about 10% and removal of loosely bound surface contamination of greater than about 80%; the submerged leaching step is operated in an agitated tank; the leaching temperature is about 77.1 °C; the leaching pressure is about atmospheric pressure; the leaching solvent includes ethyl acetate; and the total residence time is about 60 min. In embodiments of the present application, the surface washing involves deinking commercially available by Cadel; the deinking results in a delta E change of less than about 10% and removal of loosely bound surface contamination of greater than about 80%; the submerged leaching step is operated in an agitated tank, involves 2 stages; the leaching temperature is about 77.1 °C; the leaching pressure is about atmospheric pressure; the leaching solvent includes ethyl acetate; the residence time for each stage is about 30 min; the concentration of OCDD is reduced by about 98%.

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

[0208] In embodiments of the present application, wherein prior to the leaching step, the reclaimed polymer is surface washed in a surface washing step in a non-densified state 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 reclaimed polymer has a particle size of greater than about 1 mm prior to surface washing; wherein the surface washing step is performed at a temperature of about 50 °C to about 100 °C; wherein the surface washing step is performed at a pressure of about 0.1 atm to about 5 atm; wherein the surface washing step is performed for a time of about 1 min to about 60 min; and wherein the surface washing step is performed using a surface washing solvent. -1an average removal efficiency; wherein the surface washing process is of the deinking type; wherein the deinking process results in a change in delta E between the deinked polymer and the reclaimed polymer without surface printing ink of less than about 10%; wherein the leaching step is performed 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 near atmospheric pressure; wherein the residence time of each of the leaching stages is about 20 min; 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 embodiments of the present application, a method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each contaminant having a concentration; and wherein the reclaimed polymer contaminants include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the reclaimed polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a greater than about 80% reduction in loosely bound surface contamination; and c) leaching the 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed polymer and a pressure between about atmospheric pressure and about 1,000 atm for a total residence time and a residence time of each of the leaching stages at an average removal efficiency to produce a leached polymer comprising at least one of 4-tert-pentylphenol, 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. Purifying Leached Polymer

[0211] Surprisingly, it has been discovered that leached polymer in a high MW polymer solution is purified by filtration. In Figure 1A and Figure 1B The process illustrated in 1) dissolving the leached polymer in a fluid solvent at a dissolution temperature and a dissolution pressure to produce a first solution comprising dissolved polymer ( Figure 1A step c in and step d in Figure 1B ); 2) settling the first solution at a temperature and a pressure to produce a second solution comprising settled polymer ( Figure 1A step d in andFigure 1B steps e and f in FIG. 1 and steps f and g in FIG. 2); and 4) separating the twice filtered polymer from the fourth solution to produce a more pure polymer (step h in FIG. 2). Figure 1A steps e and f in FIG. 1 and steps f and g in FIG. 2); and 4) separating the twice filtered polymer from the fourth solution to produce a more pure polymer (step h in FIG. 2). Figure 1B steps e and f in FIG. 1 and steps f and g in FIG. 2); and 4) separating the twice filtered polymer from the fourth solution to produce a more pure polymer (step h in FIG. 2). Figure 1A steps e and f in FIG. 1 and steps f and g in FIG. 2); and 4) separating the twice filtered polymer from the fourth solution to produce a more pure polymer (step h in FIG. 2). Figure 1B steps e and f in FIG. 1 and steps f and g in FIG. 2); and 4) separating the twice filtered polymer from the fourth solution to produce a more pure polymer (step h in FIG. 2). Note that the values of temperature and pressure can vary from step to step. A schematic of the experimental set-up used in the dissolution, settling, filtration, and separation steps is shown in FIG. 3.

[0212] In embodiments of the present application, the more pure polymer that can be derived from the PCR stream is substantially free of contaminants, free of pigments, free of odor, uniform, and has properties similar to the native polymer.

[0213] Fluid Solvent

[0214] In embodiments of the present application, the fluid solvent has a standard boiling point of less than about 70°C. In embodiments of the present application, the fluid solvent has a standard boiling point of less than about 70°C and greater than about -45°C. In embodiments of the present application, the fluid solvent has a standard boiling point of less than about 70°C and greater than about -45°C and a standard enthalpy of vaporization of less than about +25 kJ / mol. Pressurization places the solvent with a standard boiling point lower than the operating temperature range of the present application in a state where there is little or no solvent vapor.

[0215] In embodiments of the present application, the fluid solvent is selected from the group consisting of olefins, aliphatic hydrocarbons, and mixtures thereof. In embodiments of the present application, the aliphatic hydrocarbon of the fluid solvent is selected from the group consisting of C1-C6 aliphatic hydrocarbons and mixtures thereof. In embodiments of the present application, the fluid solvent comprises n-butane, butane isomers, or mixtures thereof.

[0216] In embodiments of the present application, the fluid solvent with a standard 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 with a standard boiling point of less than 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, isohexane isomers, and other materials that can be apparent to one of ordinary skill in the art.

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

[0218] Dissolution

[0219] In embodiments of the present application, the method for purifying a reclaimed polymer includes dissolving the leached polymer in a fluid solvent at a temperature and pressure, wherein the polymer is dissolved in the fluid solvent. While not wishing to be bound by any theory, Applicants believe that the temperature and pressure can be controlled in a manner that allows for the thermodynamically favorable dissolution of the reclaimed polymer in the fluid solvent. In addition, the temperature and pressure can be controlled in a manner that allows for the dissolution of a particular polymer or polymer mixture without the dissolution of other polymers or polymer mixtures. This controlled dissolution allows for the separation of polymers from polymer mixtures.

[0220] In embodiments of the present application, the method for purifying a leached polymer includes dissolving the leached polymer in a fluid solvent that does not dissolve contaminants at the same temperature and pressure conditions. The contaminants can 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 by a subsequent solid-liquid separation step.

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

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

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

[0224] In embodiments of the application, the method for purifying a leached polymer includes dissolving the leached polyethylene in propane at a temperature of about 90 °C to about 280 °C. In embodiments of the application, the method for purifying a leached polymer includes dissolving the leached polyethylene in propane at a temperature of about 100 °C to about 220 °C. In embodiments of the application, the method for purifying a leached polymer includes dissolving the leached polyethylene in propane at a temperature of about 130 °C to about 180 °C. In embodiments of the application, the method for purifying a leached polymer includes 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 embodiments of the application, the method for purifying a leached polymer includes 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 embodiments of the application, the method for purifying a leached polymer includes 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 embodiments of the application, the method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane at a mass percent concentration of at least 0.5%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane at a mass percent concentration of up to 20%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the leached polyethylene is dissolved at a mass percent concentration of up to 12%.

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

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

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

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

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

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

[0232] In embodiments of the present application, the method for purifying leached polymer includes dissolving the leached poly(dimethylsiloxane) in a fluid solvent at a temperature and pressure, wherein the leached poly(dimethylsiloxane) is dissolved in the fluid solvent. In embodiments of the present application, the method for purifying leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 115 °C to about 280 °C. In embodiments of the present application, the method for purifying leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 120 °C to about 220 °C. In embodiments of the present application, the method for purifying leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 140 °C to about 180 °C. In embodiments of the present application, the method for purifying leached polymer includes 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 embodiments of the present application, the method for purifying leached polymer includes 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 embodiments of the present application, the method for purifying leached polymer includes 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 embodiments of the present application, the method for purifying leached poly(dimethylsiloxane) includes dissolving the leached poly(dimethylsiloxane) in n-butane at a mass percent concentration of at least 0.5%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying leached poly(dimethylsiloxane) includes dissolving the leached poly(dimethylsiloxane) in n-butane at a mass percent concentration of up to 20%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0234] In embodiments of the present application, the method for purifying a reclaimed polymer includes 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.

[0235] In embodiments of the present application, the leached polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 0.5%. In embodiments of the present application, the temperature in the dissolving step is about 110°C to about 220°C. In embodiments of the present application, the pressure in the dissolving step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0236] Settling

[0237] In embodiments of the present application, the method for purifying a polymer includes separating undissolved contaminants from a polymer solution at a temperature and pressure via a sedimentation step, wherein the polymer remains dissolved in the fluid solvent. In embodiments of the present application, the sedimentation step causes the undissolved contaminants to be subjected to a force that uniformly moves the undissolved contaminants in the direction of the force. The sedimentation force applied is typically gravity, but can also be a centrifugal force, a centripetal force, or some other force. The amount of force applied and the duration of the sedimentation will depend on several parameters, including but not limited to: the particle size of the contaminant particles, the density of the contaminant particles, the density of the fluid or solution, and the viscosity of the fluid or solution. The following equation is the relationship between the above parameters and the sedimentation velocity, which is a measure of the rate of sedimentation of the contaminants: where is the sedimentation velocity, is the density of the contaminant particles, is the density of the fluid or solution, is the acceleration due to the applied force (typically gravity), is the radius of the contaminant particles, and is the dynamic viscosity of the fluid or solution. Some of the key parameters that determine the viscosity of the 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 embodiments of the present application, the method for purifying a reclaimed polymer includes sedimenting contaminants from a polyethylene / fluid solvent solution at a temperature and pressure, wherein the polyethylene remains dissolved in the fluid solvent. In embodiments of the present application, the method for purifying a reclaimed polymer includes sedimenting contaminants from a polyethylene / fluid solvent solution at a temperature of about 90 °C to about 280 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes sedimenting contaminants from a polyethylene / fluid solvent solution at a temperature of about 110 °C to about 220 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes sedimenting 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 embodiments of the present application, the method for purifying a reclaimed polymer includes sedimenting 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 embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution at a temperature of from about 90 °C to about 280 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution at a temperature of from about 100 °C to about 220 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution at a temperature of from about 130 °C to about 180 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution at a pressure of from about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution at a pressure of from about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution at a pressure of from about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0240] In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 12%.

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

[0242] In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes settling contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 12%.

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

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

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

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

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

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

[0249] In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 application, the method for purifying a reclaimed polymer includes 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 application, the method for purifying a reclaimed polymer includes 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 application, the method for purifying a reclaimed polymer includes 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 application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes settling 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) with a solid medium.

[0250] In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0251] In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 a settled polymer, at least one dissolved contaminant, and less than at least one suspended contaminant.

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

[0253] Mechanical filtration

[0254] For the purposes of the present invention and unless specifically mentioned, the term "filtration" indicates "mechanical filtration" or "adsorptive filtration", or the term includes both types of filtration. A typical filtration system includes a filtration medium, a filtration vessel, a filter inlet, and a filter outlet. The filtration medium includes filtration particles contained within the filtration vessel. The filter inlet is in fluid communication with the filtration vessel and transports a filtration feed stream into the filtration vessel, and the filter outlet is in fluid communication with the filtration system and transports a filtrate stream out of the filtration vessel. The filtration system can include one or more filtration media, filtration vessels, and filter inlets and filter outlets in series or in parallel. Additionally, the filtration system can operate in radial flow or axial flow, or can operate in upflow, downflow, or crossflow. A non-limiting example of a radial flow filter is a candle filter. Furthermore, the filtration can be a depth filtration type or a surface filtration type, and is based on a mechanical mode of action. A non-limiting example of a mechanical mode of action is size exclusion, where suspended (dispersed) contaminants are retained by the filtration medium and thus separated from the filtration feed stream because the size of the suspended contaminants is larger than the pores of the filtration medium. As mentioned above, size exclusion is an inter-particle phenomenon.

[0255] The filtration medium used in depth filtration includes an aggregation of filtration particles, which can be homogeneous or heterogeneous. The filtration particles can be distributed uniformly or non-uniformly (e.g., layers of different filtration particles) within the filtration medium. The filtration particles forming the filtration medium also need not have the same shape or size, and can be provided in loose or interconnected form. For example, the filtration medium can include filtration particles that can be loosely associated, or partially or completely bound by a polymeric binder or other means to form a unitary structure.

[0256] Additionally, the filtration particles can be provided in a variety of shapes and sizes. For example, and without limitation, the filtration particles can be provided in simple forms such as powders, granules, fibers, and beads. The filtration particles can be provided in the shape of spheres, polyhedrons, cylinders, and other symmetrical, asymmetrical, and irregular shapes. Additionally, the filtration particles can also form complex forms such as meshes, screens, lattices, nonwoven materials, woven materials, and bound blocks, which can or can not be formed from the simple forms described above. The filtration particles can vary in size, from non-tangible filtration particles (e.g., very fine powders) to tangible filtration particles. Furthermore, the size of the filtration particles need not be uniform among the filtration particles used in any single filtration system. In fact, it can be desirable to provide filtration particles having different sizes in a single filter.

[0257] In embodiments of the application, the size of the filter particles varies between about 0.1 mm and about 10 mm. In embodiments of the application, the size of the filter particles varies between about 10 mm and about 8 mm. In embodiments of the application, the size of the filter particles varies between about 100 mm and about 5 mm. In embodiments of the application, the size of the filter particles varies between about 1 mm and about 4 mm. In embodiments of the application, the size of the filter particles varies between about 10 pm and about 100 pm. For spherical and cylindrical particles (e.g., fibers, beads, etc.), the above sizes refer to the diameter of the filter particles. For filter particles having a significantly different shape, the above sizes refer to the largest dimension (e.g., length, width, or height).

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

[0259] Non-limiting examples of filter media for surface filtration are thin layers of filter particles, porous ceramics, filter paper, filter cloth, plastic membranes, screens, non-woven materials, woven materials, porous glass frit / sintered metal, and perforated plates. In typical surface filtration, the retained contaminants form a filter cake on top of the filter media, 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 by mechanical action or backflushing. In embodiments of the application, the filter media for surface filtration is selected from the group consisting of thin layers of diatomite particles deposited onto a woven metal porous core, commonly referred to as a sock. The porous core supports the filter media and allows the filtered feed stream to flow through. Non-limiting examples of cores are perforated tubes and screen sleeves.

[0260] A filter aid can be used in the filtration. Non-limiting examples of filter aids are diatomite (also known as kieselguhr), cellulose, and perlite. These filter aids can be used as a pre-coat layer of the filtration media or added to the filtration feed stream. In the latter case (also known as bulk feed), the filter aid increases the porosity of the filter cake formed on the filtration media, thereby reducing the pressure drop through the filter cake during filtration.

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

[0262] In embodiments of the application, the surface filter comprises a candle filter. In embodiments of the application, the candle filter comprises a thin layer of diatomite deposited onto a woven metal porous core. In embodiments of the application, the diatomite layer has a thickness between about 1 mm and about 20 mm. In embodiments of the application, the diatomite layer has a thickness between about 2 mm and about 10 mm. In embodiments of the application, the diatomite layer has a thickness between about 3 mm and about 5 mm.

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

[0264] In embodiments of the application, the diatomite medium retains suspended particles with a diameter greater than about 0.3 pm. In embodiments of the application, the diatomite medium retains suspended particles with a diameter greater than about 0.8 pm. In embodiments of the application, the diatomite medium retains suspended particles with a diameter greater than about 1 pm. In embodiments of the application, the diatomite medium retains suspended particles with a diameter greater than about 1.7 pm. In embodiments of the application, the diatomite medium retains suspended particles with a diameter greater than about 4 pm.

[0265] In embodiments of the present application, a candle filter comprises a thin diatomaceous earth media deposited on a woven metal core; wherein the diatomaceous earth media has a thickness between about 2 mm and about 10 mm; wherein the diatomaceous earth media has a permeability between about 2,300 mD and 3,400 mD; and wherein the diatomaceous earth media retains suspended particles greater than about 1.7 pm in diameter.

[0266] In embodiments of the present application, a method for purifying a reclaimed 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 embodiments of the present application, a method for purifying a reclaimed polymer comprises filtering contaminants from a polyethylene / fluid solvent solution at a temperature of about 90 °C to about 280 °C. In embodiments of the present application, the temperature in the filtering step is about 110 °C to about 220 °C. In embodiments of the present application, a method for purifying a reclaimed 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 embodiments of the present application, the pressure in the filtering step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0267] In embodiments of the present application, a method for purifying a reclaimed polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 90 °C to about 280 °C. In embodiments of the present application, a method for purifying a reclaimed polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 100 °C to about 220 °C. In embodiments of the present application, a method for purifying a reclaimed polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 130 °C to about 180 °C. In embodiments of the present application, a method for purifying a reclaimed polymer comprises filtering 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 embodiments of the present application, a method for purifying a reclaimed 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 embodiments of the present application, a method for purifying a reclaimed 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 embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0269] In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes filtering contaminants from a polyethylene / n-pentane solution, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0271] In embodiments of the application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0273] In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / propane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polypropylene / propane solution, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0275] In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polystyrene / fluid solvent solution at a temperature and a pressure, wherein the polystyrene remains dissolved in the fluid solvent. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polystyrene / n-butane solution at a temperature of about 90 °C to about 280 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polystyrene / n-butane solution at a temperature of about 100 °C to about 220 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes filtering contaminants from a polystyrene / n-butane solution at a temperature of about 130 °C to about 180 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying reclaimed polymer includes filtering contaminants from a polystyrene / n-butane solution, wherein the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying reclaimed polymer includes filtering contaminants from a polystyrene / n-butane solution, wherein the polystyrene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 12%.

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

[0278] In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0279] In embodiments of the present application, a method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of alkylphenol, bisphenol, dioxin, PCB, and phthalate; b) leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed 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 for each of the leaching stages, to produce a leached polymer comprising at least one of 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 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 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 than 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 a filtered polymer, at least one dissolved contaminant, and even less than at least one suspended contaminant; In embodiments of the present application, a method for purifying a reclaimed polymer comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the reclaimed polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in greater than about 80% reduction in loosely bound surface contamination; c) leaching the 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed polymer and a pressure between about atmospheric pressure and about 1,000 atm over a total residence time and a residence time for each of the leaching stages at an average removal efficiency to produce a leached polymer comprising at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate, each having a 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 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 a 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 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.

[0280] Adsorptive filtration

[0281] In embodiments of the present invention, the method of purifying polyethylene includes contacting the contaminated polymer solution with a solid medium at a temperature and pressure at which the polymer is still dissolved in the fluid solvent. The solid medium of the present invention (also referred to throughout the present invention as an adsorptive medium or an adsorptive filtration medium) includes solid medium particles and is any solid material that removes at least some of the contaminants from a solution of recycled polyethylene dissolved in the fluid solvent of the present invention. While not wishing to be bound by any theory, the applicants believe that the solid medium removes the contaminants through a variety of mechanisms. Non-limiting examples of possible mechanisms include adsorption, absorption, electrostatic, size exclusion, ion exclusion, ion exchange, and other mechanisms that can be apparent to one of ordinary skill in the art. In addition, pigments and other contaminants common in recycled polyethylene can be polar compounds or can have polar compounds on their surface and can preferentially interact with solid media that can also be at least slightly polar. Polar-polar interactions are particularly advantageous when using a non-polar solvent (such as an alkane) as the fluid solvent.

[0282] In embodiments of the present invention, the solid medium is selected from inorganic substances, carbon-based substances, or mixtures thereof. Useful examples of inorganic substances include oxides of silicon, oxides of aluminum, oxides of iron, aluminum silicate, magnesium silicate, amorphous volcanic glass, silica, silica gel, diatomaceous earth, sand, quartz, recycled glass, alumina, perlite, Fuller’s earth, bentonite, and mixtures thereof. Useful 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 solid particles of silicon oxide (silica), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, sandy soil, 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, and lignocellulose. In embodiments of the present invention, the solid medium is selected from silica, activated alumina, silica gel, Fuller’s earth, bentonite, and mixtures thereof. In embodiments of the present invention, the solid medium is selected from activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In embodiments of the present invention, the solid medium is selected from MOF, COF, ZIF, activated carbon, activated alumina, and mixtures thereof. In embodiments of the present invention, the solid medium is selected from diatomaceous earth, activated alumina, and mixtures thereof.

[0283] A non-limiting example of a physical mode of action is physisorption (also known as physical adsorption), in which dissolved contaminants are adsorbed onto the outer or inner surface of the pores of the filtration particles due to van der Waals forces and are thus separated from the filtration 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 filtration particles due to electrostatic attraction. Filtration particles and filtration media that remove contaminants primarily by adsorption are referred to as adsorptive filtration particles and adsorptive filtration media, respectively.

[0284] Adsorptive filtration media is typically contained in a cylindrical filtration vessel as loose media or as a bound block, and adsorptive filtration can be axial flow or radial flow. Cylindrical adsorptive filtration media in axial flow form has an aspect ratio defined as the ratio of the height to the diameter of the cylindrical adsorptive filtration media. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 1. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 2. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 5. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 10. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 30. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 50. In embodiments of the present invention, the aspect ratio of the cylindrical adsorptive filtration media is equal to or greater than about 70.

[0285] In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 5 cm. In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 20 cm. In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 50 cm. In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 1 m. In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 1.5 m. In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 3 m. In embodiments of the present invention, the height of the cylindrical adsorptive filtration media is equal to or greater than about 6 m.

[0286] In embodiments of the present invention, the adsorptive filtration media is cylindrical; wherein the filtration media comprises loose adsorptive filtration particles; wherein the height of the cylindrical adsorptive media is about 122 cm; wherein the diameter of the cylindrical adsorptive media is about 1.7 cm; wherein the adsorptive filtration particles comprise activated alumina; and wherein the particle size of the adsorptive filtration particles is 7 x 14 mesh.

[0287] In embodiments of the application, the solid medium is contacted with the polymer in the vessel for a defined amount of time while the solid medium is agitated. In embodiments of the application, the solid medium is removed from the more pure polymer solution via a solid-liquid separation step. Non-limiting examples of solid-liquid separation steps include filtration, decanting, centrifugation, and settling. In embodiments of the application, the contaminated polymer solution passes through a fixed bed of solid medium. In embodiments of the application, the solid medium is replaced as needed to maintain the desired purity of the polymer. In embodiments of the application, the solid medium is regenerated and reused in the purification step. In embodiments of the application, the solid medium is regenerated during a backflush step by fluidizing the solid medium.

[0288] In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a temperature of about 90 °C to about 280 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a temperature of about 110 °C to about 220 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a 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 embodiments of the application, the method for purifying a reclaimed polymer includes contacting a 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).

[0289] In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-butane solution with a solid medium at a temperature of from about 90 °C to about 280 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-butane solution with a solid medium at a temperature of from about 100 °C to about 220 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-butane solution with a solid medium at a temperature of from about 130 °C to about 180 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-butane solution with a solid medium at a pressure of from about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-butane solution with a solid medium at a pressure of from about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-butane solution with a solid medium at a pressure of from about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0290] In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0291] In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a temperature of from about 90 °C to about 280 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a temperature of from about 100 °C to about 220 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a temperature of from about 130 °C to about 180 °C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a pressure of from about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a pressure of from about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a pressure of from about psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0292] In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0293] In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polypropylene / n-butane solution with a solid medium at a temperature of from about 90°C to about 280°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polypropylene / n-butane solution with a solid medium at a temperature of from about 100°C to about 220°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polypropylene / n-butane solution with a solid medium at a temperature of from about 130°C to about 180°C. In embodiments of the application, the method for purifying a reclaimed polypropylene includes contacting a polypropylene / n-butane solution with a solid medium at a pressure of from about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polypropylene / n-butane solution with a solid medium at a pressure of from about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting a polypropylene / n-butane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0294] In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying a reclaimed polymer includes 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 embodiments of the application, the polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0295] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polypropylene / propane solution with a solid medium at a temperature of from about 90°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polypropylene / propane solution with a solid medium at a temperature of from about 100°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polypropylene / propane solution with a solid medium at a temperature of from about 130°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polypropylene includes contacting a polypropylene / propane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polypropylene / propane solution with a solid medium at a pressure of from about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polypropylene / propane solution with a solid medium at a pressure of from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0296] In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polypropylene / propane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0297] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / fluid solvent solution with a solid medium at a temperature and pressure at which the polystyrene remains dissolved in the fluid solvent. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at a temperature of from about 90 °C to about 280 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at a temperature of from about 100 °C to about 220 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at a temperature of from about 130 °C to about 180 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at a pressure of from about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at a pressure of from about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0298] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at which the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a polystyrene / n-butane solution with a solid medium at which the polystyrene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present application, the polystyrene is dissolved at a mass percent concentration of up to 12%.

[0299] In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 application, the method for purifying a reclaimed polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of from about 115 °C to about 280 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of from about 120 °C to about 220 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of from about 140 °C to about 180 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of from about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of from about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of from about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0300] In embodiments of the application, the method for purifying recycled polymers includes 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 embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the application, the method for purifying recycled polymers includes 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 embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In embodiments of the application, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0301] In embodiments of the present invention, a method for purifying a reclaimed polymer is disclosed. The method comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of alkylphenol, bisphenol, dioxin, PCB, and phthalate; b) leaching the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed 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 for each of the leaching stages, to produce a leached polymer comprising at least one of 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 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 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 than at least one suspended contaminant; 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 a filtered polymer, at least one dissolved contaminant, and even less than 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; In an embodiment of the application, a method for purifying a reclaimed polymer is disclosed. The method comprises: a) obtaining a reclaimed polymer; wherein the reclaimed polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymer, post-industrial reclaimed (PIR) polymer, and combinations thereof; and wherein the reclaimed polymer comprises contaminants, each having a concentration; and wherein the contaminants of the reclaimed polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the reclaimed polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in greater than about 80% reduction in loosely bound surface contamination; c) leaching the 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the reclaimed polymer in a plurality of leaching stages using a leaching solvent at a temperature below the initial melting point of the reclaimed polymer and a pressure between about atmospheric pressure and about 1,000 atm over a total residence time and a residence time for each of the leaching stages at an average removal efficiency to produce a leached polymer comprising at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate, each having a 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 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 a 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 a settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant; 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; 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 a twice-filtered polymer; In embodiments of the application, the temperature in the dissolving, settling, and filtering steps is from about 110 °C to about 220 °C. In embodiments of the application, the pressure in the dissolving, settling, and filtering steps is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0302] Extraction

[0303] In embodiments of the application, the method for purifying the reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a temperature and pressure, wherein the twice-filtered polymer is substantially insoluble in the fluid solvent. While not wishing to be bound by any theory, the applicants believe that the temperature and pressure dependent solubility can be controlled in a manner that prevents the fluid solvent from completely dissolving the twice-filtered polymer; however, the fluid solvent can diffuse into the twice-filtered polymer and extract any extractable contaminants. The extractable contaminants can be residual processing aids added to the polymer, residual product formulations such as fragrances and flavorings that were in contact with the polymer, dyes, and any other extractable materials that can have been intentionally added or inadvertently incorporated into the polymer, for example, during waste collection and subsequent accumulation with other waste.

[0304] In embodiments of the present application, controlled extraction can be accomplished by fixing the temperature of the polymer / fluid solvent system and then controlling the pressure below the pressure or range of pressures at which the polymer is dissolved in the fluid solvent. In embodiments of the present application, controlled extraction is accomplished by fixing the pressure of the polymer / solvent system and then controlling the temperature below the temperature or range of temperatures at which the polymer is dissolved in the fluid solvent. Temperature and pressure controlled extraction of the leached polymer with the fluid solvent uses a suitable pressure vessel and can be configured in a manner that allows for continuous extraction of the twice filtered polymer with the fluid solvent. In embodiments of the present application, the pressure vessel can be a continuous liquid-liquid extraction column in which the molten polymer is pumped into one end of the extraction column and the fluid solvent is pumped into the same or opposite end of the extraction column. In embodiments of the present application, the fluid containing the extracted contaminants is removed from the process. In embodiments of the present application, the fluid containing the extracted contaminants is purified, recovered and recycled for use in the extraction step or a different step in the process. In embodiments of the present application, the extraction can be carried out in a batch process in which the twice filtered polymer is fixed in a pressure vessel and the fluid solvent is pumped continuously through the fixed polymer phase. The extraction time or amount of fluid solvent used will depend on the desired purity of the final purer polymer and the amount of extractable contaminants in the starting twice filtered polymer. In embodiments of the present application, the fluid containing the extracted contaminants is contacted with a solid medium in a separate step as described below. In embodiments of the present application, the method for purifying the twice filtered polymer includes contacting the twice filtered polymer with a fluid solvent at a temperature and pressure at which the twice filtered polymer is molten and in a liquid state. In embodiments of the present application, the twice filtered polymer is contacted with a fluid solvent at a temperature and pressure at which the twice filtered polymer is in a solid state.

[0305] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a temperature and a pressure, wherein the polyethylene remains substantially unsolubilized. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a temperature and a pressure, wherein the twice-filtered polymer remains substantially unsolubilized. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a temperature of from about 80°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a temperature of from about 110°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a pressure of from about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polymer with a fluid solvent at a pressure of from about 400 psig (2.76 MPa) to about 2,400 psig (16.55 MPa). In embodiments of the present application, the pressure in the extraction step is less than about 1,100 psig (7.58 MPa).

[0306] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-butane at a temperature of from about 80°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-butane at a temperature of from about 100°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-butane at a temperature of from about 130°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-butane at a pressure of from about 400 psig (2.76 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-butane at a pressure of from about 800 psig (5.52 MPa) to about 5,000 psig (34.47 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 4,500 psig (31.03 MPa).

[0307] In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a temperature of from about 80°C to about 280°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a temperature of from about 100°C to about 220°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a temperature of from about 130°C to about 180°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a pressure of from about 400 psig (2.78 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a pressure of from about 800 psig (5.52 MPa) to about 2,800 psig (19.31 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a pressure of from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0308] In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a temperature of from about 80°C to about 280°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a temperature of from about 100°C to about 220°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a temperature of from about 130°C to about 180°C. In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a pressure of from about 400 psig (2.78 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a pressure of from about 800 psig (5.52 MPa) to about 2,800 psig (19.31 MPa). In embodiments of the application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polyethylene with n-pentane at a pressure of from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0309] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polypropylene with propane at a temperature of about 80°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polypropylene with propane at a temperature of about 100°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polypropylene with propane at a temperature of about 130°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polypropylene with propane at a pressure of about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polypropylene with propane at a pressure of about 1,000 psig (6.89 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polypropylene with propane at a pressure of about 2,000 psig (13.79 MPa) to about 4,000 psig (27.58 MPa).

[0310] In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with a fluid solvent at a temperature and pressure wherein the twice-filtered polystyrene remains substantially unsolubilized. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with n-butane at a temperature of about 90°C to about 280°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with n-butane at a temperature of about 100°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with n-butane at a temperature of about 120°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with n-butane at a pressure of about 500 psig (3.45 MPa) to about 5,000 psig (34.47 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with n-butane at a pressure of about 1,000 psig (6.89 MPa) to about 4,000 psig (27.58 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes contacting the twice-filtered polystyrene with n-butane at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0311] In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with a fluid solvent at a temperature and a pressure, wherein the twice-filtered poly(dimethylsiloxane) remains substantially unsolubilized. In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with n-butane at a temperature of from about 100°C to about 280°C. In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with n-butane at a temperature of from about 115°C to about 220°C. In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with n-butane at a temperature of from about 120°C to about 180°C. In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with n-butane at a pressure of from about 200 psig (1.38 MPa) to about 1,800 psig (12.41 MPa). In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with n-butane at a pressure of from about 300 psig (2.07 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present application, the method for purifying reclaimed polymer includes contacting twice-filtered poly(dimethylsiloxane) with n-butane at a pressure of from about 500 psig (3.45 MPa) to about 1,000 psig (6.89 MPa).

[0312] In embodiments of the present application, the method for purifying reclaimed polymer includes extracting the twice-filtered polymer with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of from about 80°C to about 280°C and a pressure of from about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) to produce a fifth solution comprising an extracted polymer.

[0313] Separation

[0314] In embodiments of the present application, the method for purifying reclaimed polymer includes separating the extracted polymer from the fifth solution at a temperature and a pressure, wherein the extracted polymer precipitates out of solution and does not resolubilize in the fluid solvent to produce a purer polymer. For the purposes of the present application, the terms "extracted polymer" and "purer polymer" are used interchangeably.

[0315] In embodiments of the present application, precipitating a purer polymer from a fluid solvent is accomplished by decreasing the pressure at a fixed temperature. In embodiments of the present application, precipitating a purer polymer from a fluid solvent is accomplished by decreasing the temperature at a fixed pressure. In embodiments of the present application, precipitating a purer polymer from a fluid solvent is accomplished by increasing the temperature at a fixed pressure. In embodiments of the present application, precipitating a purer polymer from a fluid solvent is accomplished by decreasing both the temperature and pressure. By controlling the temperature and pressure, the solvent can be partially or completely converted from a liquid to a gas phase. In embodiments of the present application, 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% 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, decanting, centrifugation, and settling.

[0316] In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from a polyethylene / fluid solvent solution at a temperature and pressure, wherein the polyethylene precipitates from the solution. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from a polyethylene / n-butane solution at a temperature of about 0 °C to about 280 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from a polyethylene / n-butane solution at a temperature of about 50 °C to about 175 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from a polyethylene / n-butane solution at a temperature of about 100 °C to about 220 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the 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 embodiments of the present application, the method for purifying a reclaimed polymer includes separating the 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 embodiments of the present application, the method for purifying a reclaimed polymer includes separating the 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).

[0317] In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from the polyethylene / n-pentane solution at a temperature from about 0 °C to about 280 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from the polyethylene / n-pentane solution at a temperature from about 30 °C to about 150 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from the polyethylene / n-pentane solution at a temperature from about 50 °C to about 130 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from the polyethylene / n-pentane solution at a pressure from about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from the polyethylene / n-pentane solution at a pressure from about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polyethylene from the polyethylene / n-pentane solution at a pressure from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0318] In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / fluid solvent solution at a temperature and pressure wherein the polypropylene precipitates from the solution. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / n-butane solution at a temperature from about 0 °C to about 220 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / n-butane solution at a temperature from about 100 °C to about 200 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / n-butane solution at a temperature from about 130 °C to about 180 °C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / n-butane solution at a pressure from about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / n-butane solution at a pressure from about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / n-butane solution at a pressure from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0319] In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / propane solution at a temperature of about -42°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / propane solution at a temperature of about 0°C to about 150°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / propane solution at a temperature of about 50°C to about 130°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes 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 embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polypropylene from the polypropylene / propane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0320] In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / fluid solvent solution at a temperature and pressure wherein the polystyrene precipitates from the solution. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / n-butane solution at a temperature of about 0°C to about 220°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / n-butane solution at a temperature of about 100°C to about 200°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present application, the method for purifying a reclaimed polymer includes separating the polystyrene from the polystyrene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0321] In embodiments of the present application, the method for purifying reclaimed polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure, wherein the poly(dimethylsiloxane) precipitates from the solution. In embodiments of the present application, the method for purifying reclaimed polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 0 °C to about 220 °C. In embodiments of the present application, the method for purifying reclaimed polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115 °C to about 200 °C. In embodiments of the present application, the method for purifying reclaimed polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120 °C to about 180 °C. In embodiments of the present application, the method for purifying reclaimed polymer includes 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 embodiments of the present application, the method for purifying reclaimed polymer includes 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 embodiments of the present application, the method for purifying reclaimed polymer includes 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).

[0322] In embodiments of the present application, the polymer is separated twice from the fourth solution to produce a more pure polymer. In embodiments of the present application, the 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 more pure polymer.

[0323] IX. Test Method

[0324] The test method described herein is used to measure the effectiveness of various polymer purification methods. Specifically, the method demonstrates the effectiveness of a given purification method in improving color and translucency / clarity (i.e., making the color and opacity of the reclaimed 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 (especially volatile compounds that contribute to the malodor of the reclaimed polymer), and reducing or eliminating polymer contamination (i.e., polyethylene contamination in polypropylene).

[0325] Color and opacity measurements

[0326] Color and opacity / translucency of a polymer are important parameters in determining whether the polymer can achieve the desired visual aesthetics of an article manufactured from the polymer. Recycled polymers, particularly PCR polymers, are often dark in color and opaque due to residual pigments, fillers, and other contaminants. Color and opacity measurements are therefore important parameters in determining the effectiveness of a method for purifying a polymer.

[0327] Prior to color measurement, a sample of one of the polymer powder or pellets is compression molded into a 30 mm wide x 30 mm long x 1 mm thick square test specimen (with rounded corners). The powder sample is first densified at room temperature (about 20-23 °C) by cold pressing the powder into a sheet using clean, unused aluminum foil as a contact release layer between the stainless steel platens. Approximately 0.85 g of the cold-pressed powder or pellets is then pressed into a test specimen on a C-Style Carver Press (Carver, Inc., Wabash, IN 46992-0554 USA) preheated to 200 °C using aluminum platens, unused aluminum foil release layer, and a stainless steel shim with a cavity corresponding to the aforementioned dimensions of the square test specimen. The sample is heated for 5 min prior to applying pressure. After 5 min, the pressings are then compressed with at least 2 tons (1.81 metric tons) of hydraulic pressure for at least 5 seconds, then released. The molding stack is then removed and placed between two thick flat metal heat sinks for cooling. The aluminum foil contact release layer is then peeled off the sample and discarded. The flash around the sample on at least one side is peeled to the edge of the mold, and the sample is then pushed through the form. Each test specimen is visually evaluated for void / bubble defects, and only samples without defects in the color measurement area (0.7" (17.78 mm) minimum diameter) are used for color measurement.

[0328] The color of each sample is characterized using the International Commission on Illumination (CIE) L , a , b Three-dimensional color space. The dimensions L are measures of sample brightness, where L = 0 corresponds to the darkest black sample, and L = 100 corresponds to the brightest white sample. The dimensions a is a measure of the red or green color of the sample, with positive values a corresponding to red, and negative values a corresponding to green. The dimension b is a measure of the blue or yellow color of the sample, with positive values b corresponding to yellow, and negative values b corresponding to blue. The L a b values of each 30 mm wide x 30 mm long x 1 mm thick square test sample were measured on a HunterLab Model LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-5280, USA) configured with D65 as the standard illuminant, an observation angle of 10°, an area diameter viewing angle of 1.75" (44.45 mm), and a port diameter of 0.7" (17.78 mm).

[0329] The opacity of each sample, which is a measure of how much light is transmitted through the sample (i.e., a measure of the translucency of the sample), was determined using the aforementioned Hunter Lab spectrophotometer in the contrast ratio opacity mode. Two measurements were made to determine the opacity of each sample. Once with a white backing as the background to measure the lightness value of the sample and once with a black backing as the background to measure the lightness value of the sample The opacity was then calculated from the lightness values using the following equation: .

[0330] Elemental analysis

[0331] Many recycled polymers have unacceptably high concentrations of heavy metal contamination. The presence of heavy metals (e.g., lead, mercury, cadmium, and chromium) can prevent the use of recycled polymers in certain applications, such as food or pharmaceutical contact applications or medical device applications. Therefore, it is important to measure the concentration of heavy metals when determining the effectiveness of a method for purifying a polymer.

[0332] 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), depending on the availability of the sample, from n = 2 to n = 6. The samples were digested using an Ultrawave microwave digestion protocol consisting of a 20 min ramp to 125 °C, a 10 min ramp to 250 °C, and a 20 min hold at 250 °C. The digested samples were cooled to room temperature. After the addition of 0.25 mL of 100 ppm Ge and Rh as internal standards, the digested samples were diluted to 50 mL. To assess the accuracy of the measurements, digest spikes were prepared by spiking virgin polymer. The virgin polymer spiked samples were weighed by the same procedure described above and spiked with the appropriate amount of the individual elements of interest, including Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb. The spikes were prepared at two different levels: “low level spike” and “high level spike”. Each spike was prepared in triplicate. In addition to the virgin polymer spike, blank spikes were also spiked to confirm that no errors occurred during pipetting and to track recycling throughout the process. The blank spike samples were also prepared in triplicate at two different levels and treated in the same manner as the virgin polymer spikes 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 by diluting pure standard reference solutions with 4 mL of concentrated nitric acid and 1 mL of concentrated HF 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-QQQ MS, which was optimized according to the manufacturer’s recommendations. The m / z of each analyte monitored and the collision cell gas used for 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.

[0333] Residual ash content

[0334] Many recycled polymers contain various fillers, such as calcium carbonate, talc, and glass fibers. While useful in the original application of the recycled polymer, these fillers alter the physical properties of the polymer in ways that are undesirable for the next application of the recycled polymer. Thus, measuring the amount of fillers is important in determining the effectiveness of a method for purifying a polymer.

[0335] Thermogravimetric analysis (TGA) was performed to quantify the amount of non-combustible material in the sample, sometimes also referred to as ash content. About 5-15 mg of sample was loaded onto a platinum sample pan and heated at a rate of 20 °C / min to 700 °C in a TA Instruments Q500 TGA instrument in an air atmosphere. The sample was held isothermal at 700 °C for 10 minutes. After the isothermal hold, the residual mass percent was measured at 700 °C.

[0336] Odor analysis

[0337] Odor sensory analysis was performed by placing about 3 g of each sample in a 20 mL glass vial and equilibrating the sample at room temperature for at least 30 min. After equilibration, each vial was opened and the headspace was bunny sniffed by a trained panelist to determine odor intensity and descriptor characteristics. Odor intensity was ranked according to the following scale: 5 = very strong; 4 = strong; 3 = moderate; 2 = weak to moderate; 1 = weak; and 0 = no odor.

[0338] Polymer contamination analysis

[0339] Many recycled polymers, particularly those derived from mixed stream sources, can contain undesirable polymer contamination. Without wishing to be bound by any theory, polymer contamination (e.g., polyethylene contamination in a polypropylene) can affect the physical properties of the polymer due to the presence of heterogeneous phases and weak interfaces resulting therefrom. In addition, polymer contamination can also increase the opacity of the polymer and have an impact on color. Thus, measuring the amount of polymer contamination is important in determining the effectiveness of a method for purifying a polymer.

[0340] Differential scanning calorimetry (DSC) was used to assess semi-crystalline polymer contamination. For example, to measure the amount of polyethylene contamination in polypropylene, a set of five polypropylene / polyethylene blends was prepared using 2 wt%, 4 wt%, 6 wt%, 8 wt%, and 10 wt% Formolene® HB5502F HDPE (Formosa Plastics Corporation, USA) in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, B.V.). About 5-15 mg of each sample was sealed in an aluminum DSC pan and analyzed on a TA Instruments Q2000 model DSC using the following method: 1. Equilibrate at 30.00 °C 2. Ramp at 20.00 °C / min to 200.00 °C 3. Mark the end of cycle 0 4. Ramp at 20.00 °C / min to 30.00 °C 5. Mark the end of cycle 1 6. Ramp at 20.00 °C / min to 200.00 °C 7. Mark the end of cycle 2 8. Ramp at 20.00 °C / min to 30.00 °C 9. Mark the end of cycle 3 10. Ramp at 5.00 °C / min to 200.00 °C 11. Mark the end of cycle 4 The 128 °C HDPE peak melting enthalpy was calculated for each known HDPE content sample using the 5.00 °C / min DSC thermogram. As shown in Figure 2 a linear calibration curve was established that plotted the melting enthalpy versus the known HDPE concentration in wt%.

[0341] The same DSC equipment and method described above is used to analyze samples with unknown PE content. The PE content is calculated using the calibration curve described above. The particular HDPE used to generate the calibration curve will likely have a different degree of crystallinity than the polyethylene (or polyethylene blend) contamination that can be present in the recycled polymer samples. The degree of crystallinity can independently affect the measured enthalpy of fusion of the polyethylene, and thus affect the resulting calculation of the polyethylene content. However, the DSC test method described herein is intended as a relative measure to compare 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, the method can be applied to other semi-crystalline polymers and the measurement of peaks in the DSC thermogram using different temperature ranges. In addition, alternative methods such as nuclear magnetic resonance (NMR) spectroscopy can also be used to measure the amount of semi-crystalline and amorphous polymer contamination in a sample.

[0342] Analytical determination of chemical contaminants

[0343] For pesticides: EN 15662:2018-07 Modular QuEChERS method was applied. For alkylphenol ethoxylates, alkylphenols and bisphenols the following technique was applied: the sample was cut, homogenized and weighed; then, internal standards (deuterated bisphenol A) were added, then the sample was extracted with hexane at room temperature, derivatized with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide) and the contaminant levels were determined by GC-MSD. For dioxins, furans and PCBs: ISO / IEC 17025:2005 method was applied. The sample was cut into small pieces, 13C / 12C labeled PCDD / F internal standards were added to aliquots of the sample material, extracted with hexane and H2SO4 and the matrix was destroyed for 1 hour, re-extracted with hexane (3 times for 30 min), cleaned up with a multi-step chromatography, 13C / 12C labeled PCDD / F recovery standards were added to the measurement solution and quantified by internal labeled PCDD / F standards (isotope dilution technique and internal standard technique). For organotin: the method follows the EDANA protocol for organotin compounds in absorbent hygiene products and their constituent raw materials (WSP 351). More specifically, the sample was extracted with a solution of sodium diethyldithiocarbamate in ethanol, alkylated with sodium tetraethylborate and transferred into the organic phase by extraction with hexane. Then, the tetra-substituted organotin compounds were separated by using capillary gas chromatography, evidenced with AED or MS as detectors. GC-ICP-MS was used as detector system for organometallic analysis. For phthalates: the sample was cut, homogenized and weighed. Then internal standards were used and extraction was performed with hexane at room temperature. The extracted phthalates were then identified and quantified by GC-MSD. For PAH: the sample was cut, homogenized and weighed. Then, internal standards of deuterated PAH were added and the sample was extracted with hexane. The extracted PAH were purified with silica gel, concentrated and then characterized by GC-MSD.

[0344] Amount of loosely bound surface contamination

[0345] The amount of loosely bound surface contamination was determined by the following method: about 20 g of plastic was added to a 1,000 mL round bottom flask. About 300 mL of distilled water was added to the 1,000 mL round bottom flask. The round bottom flask was capped and then vigorously shaken for about 60 s. The water was decanted from the flask. About 600 mL of additional distilled water was added to the 1,000 mL flask and then immediately decanted, leaving the original reclaimed polymer with a small amount of water. The reclaimed polymer was removed from the round bottom and allowed to dry in a convection oven at 60 °C overnight. The mass change % of the plastic was the amount of loosely bound surface contamination.

[0346] Color measurements for ΔE calculation

[0347] Color measurements were obtained with a Minolta Spectrophotometer, model CM580d. The "white" portion of the Leneta card was used as the common background and as the reference point for the calculation of delta E. Delta E is the color difference between the sample color and the reference color. Color measurements were made using D65 illuminant and a 10° observer. A minimum of three measurements were made for each of the samples of compressed thermoplastic starch composition. The L, a, b values were averaged and reported along with the delta E value. The delta E value for a pure white Leneta card is zero, and a positive deviation from zero indicates an increase in discoloration. Those skilled in the art will know how to calculate the delta E value.

[0348] X. Examples

[0349] Comparative Example 1 - Purification of high care post-consumer film using commercially available water wash process #1 followed by melt densification

[0350] A feed of recycled polymer consisting of high care post-consumer film #1 was fed into a commercially available purification process. The cleaning process consisted of shredding, various water wash steps, drying, and melt densification. Shredding homogenized the material while reducing its basic size. The aqueous solution wash should effectively remove surface contamination. However, due to the low solubility of chemical contaminants in water, the ability of this method to remove a significant amount of permeable contamination should be minimal. A small amount of volatile bulk contamination should be removed during drying and melt densification, but overall, bulk contamination should be largely unaffected. In addition, the source of the high care post-consumer film used as the recycled polymer had limited chemical contamination as evidenced by low levels of pesticides, dioxins, and phthalates. The recycled polymer and purer plastic were analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) for classes of chemical contaminants commonly found in recycling materials using the methods disclosed in Section IX. After purification, the purer plastic contained slightly reduced levels of chemical contamination as shown in Table 3. The removal efficiency for the five selected substances was as follows: for 4-tert-amyphenol, the removal efficiency was 0%. For bisphenol A, the removal efficiency was 94%. For OCDD, the removal efficiency was 78%. For PCB 118, the removal efficiency was 68%. For di-2-ethylhexyl phthalate, the removal efficiency was 22%. The average removal efficiency for the five selected contaminants was about 52%.

[0351] Table 3

[0352] Purification of high care post-consumer (HCPC) using commercially available water wash process #1

[0353] Source #1

[0354] Comparative Example 2 - Purification of High Care Post Commercial Film #2 using commercially available water wash process #2 followed by melt densification

[0355] A recycle polymer consisting of High Care Post Commercial Film #2 was fed into a commercially available purification process to produce a purer plastic. The cleaning process consisted of shredding, hot water washing, drying, and melt densification. As in the case of water wash process #1, this process should remove surface contamination, but has limited ability to remove substantial permeable contamination. The recycle polymer and purer plastic were analyzed for classes of chemical contaminants typically found in recycling materials by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 4. The High Care film source (recycle polymer) had limited chemical contamination, as evidenced by low levels of dioxins, PCBs, phthalates, and PAHs. The purer plastic contained a mixture of increased and slightly reduced levels of chemical contamination. The increase in certain chemical contaminants can 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 efficiency for the five selected substances was as follows: for 4-tert- Amylphenol, the removal efficiency was 0%. For Bisphenol A, the removal efficiency was 96%. For OCDD, the removal efficiency was 0%. For PCB 118, the removal efficiency was 68%. For Di-2-ethylhexyl phthalate, the removal efficiency was 0%. The average removal efficiency for the five selected contaminants was about 14%.

[0356] Table 4

[0357] Purification of High Care Post Commercial (HCPC) using commercially available water wash process #2

[0358] Source #2

[0359] Comparative Example 3A - Purification of Post Commercial #1 film using commercially available de-inking process from Cadel.

[0360] A recycled polymer consisting of commercial post-consumer film #1 was fed into a purification process called deinking (http: / / cadeldeinking.com / en / ) available on the market from Cadel to produce a purer plastic. The method consists of shredding, aqueous deinking, water washing / rinsing, and drying. According to the patented technology, the deinking step involves elevated temperature, elevated pH, and surfactants. The various washing steps should effectively remove surface contamination. In addition, due to the elevated temperature, a small amount of bulk permeable contamination will be removed, which will increase the diffusion rate, and due to the surfactant / pH combination, the solubility of the contaminants in water can increase. However, a lower bulk extraction rate is expected. The incoming recycled polymer was determined to have 0.125 wt% loosely bound surface contamination compared to about 0.02 wt% of the purer plastic in the form of shreds. Thus, the cleaning process removed greater than 80% of the incoming loosely bound surface contamination. After cleaning but before analyzing the recycled polymer for chemical contamination, the shreds were melt densified using a single screw extruder at 190 °C to produce pellets. The pellets were ground to an average diameter of 300-500 pm. The recycled polymer and the purer plastic were analyzed by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) for the classes of chemical contaminants typically found in recycling materials using the methods disclosed in Section IX, as shown in Table 5. The recycled polymer contained moderate levels of chemical contamination, indicating that the commercial post-consumer film lacked a high stewardship life cycle. For example, the incoming dioxin such as OCDD was 40 times the LOQ, which is higher than the high-stewardship sources of the previously described Comparative Example 1, Comparative Example 2, and Comparative Example 5. In addition, this particular source had high levels of paper contamination, which can form additional chemical contamination once remelted for densification / pelletization. This particular source was particularly high in alkylphenols (about 1,000 times the LOQ), further indicating the level of chemical contamination within this recycling source. The recycled polymer consisted of shredded film, where most of the melt together into a plastic mass. Thus, the effectiveness of surface washing techniques using this source was inhibited to some extent due to the inability to access the fully contaminated surface. The purer plastic contained reduced levels of chemical contamination after the deinking process. The removal efficiency for the five selected substances was as follows: for 4-tert-amylphenol, the removal efficiency was 71%. For bisphenol A, the removal efficiency was 0%. For OCDD, the removal efficiency was 60%. For PCB 118, the removal efficiency was 0%. For di-2-ethylhexyl phthalate, the removal efficiency was 22%. The average removal efficiency for the five selected contaminants was about 31%.

[0361] Comparative Example 3B - Purification of post-consumer film #1 using commercially available deinking process from Cadel.

[0362] 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 incoming 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 flakes of post-domestic film #1 were melt densified and pelletized using an extruder. The pelletized material was ground to an average particle size of 300 μm to 500 μm. 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 for the types of chemical contaminants commonly found in recycled materials, 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 7xLOQ; alkylphenol ethoxylates were approximately 1,000xLOQ; and dioxins and phthalates were approximately 300xLOQ. 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 PCB118, 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%.

[0363] Table 5

[0364] Post-commercial (PC) Source #1 and Post-home (PH) Source #1 were purified using a commercially available deinking process from Cadel

[0365] Comparative Example 4—Purification of High-Shelf Commercial Post-#3 Membrane Using a Commercially Available Deodorization Process

[0366] A recycled polymer consisting of high inventory commercial post-consumer film #3 was fed into a purification process known as deodorization technology. This method involves exposing the particulate feed to moderate temperatures and continuous air flushing. As such, this cleaning technology primarily removes volatile surface and bulk contamination. However, a large portion of chemical contaminants associated with controlled end markets are highly non-volatile. The classes of chemical contaminants commonly found in recycled materials were analyzed in the recycled polymer and purer plastic by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX, as shown in Table 6. The high inventory film source #3 had limited chemical contamination, as evidenced by low levels of dioxins, PCBs, phthalates, and PAHs. The purer plastic contained slightly reduced levels of chemical contamination. The removal rates for the five selected substances were as follows: for 4-tert-pentylphenol, the removal efficiency was 88%. For bisphenol A, the removal efficiency was 96%. For OCDD, the 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 contaminants was about 41%.

[0367] Table 6

[0368] Purification of high inventory commercial post-consumer (HCPC) using commercially available deodorization process

[0369] Source #3

[0370] Generally, established methods for purifying / cleaning film and other plastic waste, including water washing, de-inking, and devolatilization, currently do not sufficiently remove chemical contaminants, especially in high inventory sources. Even with high inventory sources, chemical contamination remains and is not completely removed, which can limit the end use by certain consumers. Therefore, there is an unmet need for a cleaning technology that can more completely remove chemical contamination sufficient for highly contaminated sources and for any market requiring purer recycled materials.

[0371] Example 1 - Whole purification using submersion extraction in a CSTR of post-consumer film #1 with ethyl acetate at boiling point and atmospheric pressure

[0372] To a 5 L stirred round bottom flask was added 2,000 g of ethyl acetate. The flask was fitted with a mechanical stirrer, a reflux condenser, and a heating mantle. The mechanical s...

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 first fluid solvent 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 adsorptive 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; g. extracting the twice filtered polymer with a second fluid solvent having a normal boiling point of less than 70°C at a temperature of 80°C to 280°C and a pressure of 150 psig (1.03 MPa) to 8,000 psig (55.16 MPa) to produce a fifth solution comprising the extracted polymer; as well as h. separating the extracted polymer from the fifth 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 the regenerated polymer is surface washed in a non-densified state in one or more surface washing steps prior to the leaching step; wherein the one or more surface washing steps result in a reduction of loosely bound surface contamination of greater than 80%; and wherein the regenerated polymer has an average surface area to volume ratio of greater than 1 mm −1 prior to the surface washing steps.

9. The method of claim 1 , wherein the regenerated polymer is surface washed in a non-densified state in a surface washing step prior to the leaching step to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination of greater than 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 min; 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.

10. The method of claim 1, wherein the extracted polymer is separated from the fifth 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).

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

12. The method of claim 1, wherein the first fluid solvent or the second 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 first fluid solvent or the second 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, filtering, and extracting steps is 110°C to 220°C, and the pressure in the extracting step is 400 psig (2.76 MPa) to 2,400 psig (16.55 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 greater than 80% reduction in loosely bound surface contamination; 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, each having a concentration; wherein the average removal efficiency is greater than 55%; d. dissolving the leached polymer in a first fluid solvent 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; h. extracting the twice filtered polymer with a second fluid solvent having a normal boiling point of less than 70°C at a temperature of 80°C to 280°C and a pressure of 150 psig (1.03 MPa) to 8,000 psig (55.16 MPa) to produce a fifth solution comprising the extracted polymer; as well as i. separating the extracted polymer from the fifth 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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