Method for purifying recycled polymers

Abstract

A method for purifying recycled polymer into a higher purity polymer is disclosed. In an embodiment of the invention, the method includes obtaining recycled polymer, leaching various contaminants using a leaching solvent to produce a leached polymer, extracting the leached polymer with a first fluid solvent to produce an extracted polymer, and then dissolving the extracted polymer in the solvent to produce a first solution containing dissolved polymer. The first solution is precipitated and then filtered. The higher purity 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 higher purity polymers by combining immersion leaching and purification processes and using leaching and pressurized solvents. More specifically, the recycled polymers are selected from the group consisting of post-consumer reclaimed (PCR) polymers, post-industrial reclaimed (PIR) polymers, and combinations thereof. The higher purity polymers are colorless or transparent, odorless, and virtually unrecycled. The present invention is particularly useful for purifying polyolefins such as polyethylene and polypropylene. [Background technology]

[0002] Synthetic polymers are used in every aspect of daily life due to their relatively low production costs and good balance of material properties. They are used in a wide variety of applications, such as packaging, automotive parts, medical devices, and consumer goods. To meet the high demand for these applications, hundreds of millions of tons of synthetic polymers are produced worldwide each year. The overwhelming majority of these polymers are produced from increasingly scarce fossil resources, such as petroleum and natural gas. Furthermore, the production of these synthetic polymers from fossil resources results in the emission of greenhouse gases (GHGs), primarily CO2, into the atmosphere.

[0003] The ubiquitous use of synthetic polymers generates millions of tons of plastic waste each year. While the majority of plastic waste is landfilled through municipal solid waste programs, a significant portion remains as litter in the environment, where it can cause aesthetic problems and harm ecosystems. Plastic waste often finds its way into river systems and ultimately into the ocean.

[0004] To alleviate the problems associated with the widespread use of plastics, plastic recycling has emerged as one solution. Recovering and reusing plastics avoids waste from landfills and reduces the demand for newly produced virgin plastics from fossil-based resources, thereby reducing GHG emissions. In developed countries such as the United States and the European Union, plastic recycling rates are increasing due to growing awareness among consumers, businesses, and manufacturers. Most recycled materials, including plastics, are mixed into a single stream, which is collected and processed at material recovery facilities (MRFs). At MRFs, the materials are sorted, cleaned, and packaged for resale. Plastics may be separated into individual materials, such as high-density polyethylene (HDPE) or poly(ethylene terephthalate) (PET), or may be in a mixed stream with other common plastics (e.g., polypropylene (PP), low-density polyethylene (LDPE), liner low-density polyethylene (LLDPE), poly(vinyl chloride) (PVC), polystyrene (PS), polycarbonate (PC), and polyamide (PA)). The single or mixed streams can then be further separated, cleaned, and reprocessed at a plastics recovery facility (PRF) into pellets suitable for reuse in plastics processes such as blow molding, profile extrusion, injection molding, and film manufacturing.

[0005] Recycled plastics are separated into predominantly homogeneous streams and then washed with aqueous and / or caustic solutions. However, the final reprocessed pellets often remain highly contaminated with undesirable waste impurities, such as spoiled food residues and residual flavorings. Additionally, recycled plastic pellets, with the exception of those derived from recycled beverage containers, are heavily colored with a mixture of dyes and pigments commonly used to color plastic articles. While some applications (e.g., black plastic containers for paint, hidden automotive parts) are less sensitive to color and contamination, the majority require colorless pellets. The need for high-quality, "virgin" recycled resins is particularly important in food and pharmaceutical contact applications, such as food packaging. In addition to contamination from impurities and mixed colorants, many recycled resin products are often heterogeneous in chemical composition and may contain significant amounts of polymer contaminants (e.g., polyethylene (PE) contamination in recycled PP, or vice versa).

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

[0007] Films are a special case of recycled plastics, primarily composed of polyolefins. Film recycling presents unique challenges. The recycled film supply stream can be divided into two general categories: 1) pre-consumer recycled films, which include both in-plant scrap / off that can be reused in the same process that produced the recycled film and PIR films, which are films generated by in-plant waste that are not used in the same process that produced the recycled film; and 2) PCR films, which include post-consumer recycled films, which are films used commercially but not directly by household consumers (e.g., in-store shrink wrap, pallet wrap, wholesale bags, furniture wrap, agricultural film, etc.), and post-consumer recycled films, which are films used commercially directly by household consumers (e.g., retail bags, retail food packaging, overwrap for diapers and hygiene products, trash bags, etc.). PIR film waste for recycling is collected at the plant level for controlled end-markets, which may or may not involve significant cleaning steps before recycling. PCR film is collected at the point of sale and transported to various film-specific PRFs for various cleaning procedures and distribution to end markets. In the United States, post-consumer film is primarily collected through store collection programs, where end consumers return film to local store collection bins. Film-based PRFs collect film waste and then send it to end markets after sorting and cleaning. Utilization of film-based recycled materials is very limited due to contamination. Film is more susceptible to contamination than other forms due to its high surface area-to-volume ratio, which increases the potential for external contamination. Currently, most recycled film-based plastics are downcycled into non-circular, size-limited markets such as plastic lumber. As film-based waste collection increases, the need for end markets beyond plastic lumber is essential. Ideally, film-based waste would ultimately be reused in film-based applications, ensuring continued circularity.

[0008] End markets cannot grow unless pollution is significantly reduced. Given the large volume of film used in demanding applications, it is important that recycled plastics from these markets re-enter the same end markets to maintain circularity. Therefore, the ability to remove even higher levels of pollutants is important to achieve circularity and reduce GHG emissions and plastic pollution. Plastic pollution is an even more serious issue for film given the film's very large surface area per use and the mobility of waste in the environment via both air and water.

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

[0010] Mechanical recycling, also known as secondary recycling, is the process of converting recycled plastic waste into a reusable form for subsequent manufacturing. A more detailed discussion of mechanical recycling and other plastic recovery processes is found in SM Al-Salem, P. et al., Waste Management, 29(10)(2009), 2625-2643. Mechanical recycling of rigid plastics typically involves some form of surface cleaning, followed by drying and melt densification. The melt densification process typically involves melt filtration and devolatilization. While advances in mechanical recycling technology have resulted in some improvements in the quality of recycled polymers, mechanical decontamination approaches have fundamental limitations, such as the physical entrapment of pigments within the polymer matrix. Therefore, even with improvements in mechanical recycling technology, the heavy color and high levels of chemical contamination in currently available recycled plastic waste prevent widespread use of recycled resins by the plastics industry. Film-based materials can be processed using dry and wet processes. In dry processes, a controlled film stream is typically shredded, dried, and then melt-extruded into its final form. Melt filtering and devolatilization are typically part of the extrusion process. In wet processes, a controlled film stream is typically chopped, washed in one or more aqueous solutions, dried, and then melt extruded into a final form. Melt filtering and devolatilization are typically part of the extrusion process. The above methods are generally acceptable for removing intentional surface contaminants such as paper labels and unintentional surface contaminants such as dirt, but are inadequate for removing bulk contaminants.

[0011] U.S. Patent No. 10,022,725 discloses a mechanical recycling method for cleaning linear low-density polyethylene (LLDPE) / LDPE film for use in recycling. U.S. Patent No. 10,022,725 further discloses a shredding step, a first water washing step, a second size reduction step including wet grinding, one or more friction washing steps, at least one of which uses hot water, one or more drying steps, and a compression step. While this method may be very effective at removing some loosely bound surface contamination, it is ineffective at removing bulk contamination due to the very low solubility of bulk contaminants in aqueous cleaning media and / or the limited diffusibility of bulk contaminants in plastics.

[0012] U.S. Patent No. 9,616,595 discloses a mechanical recycling method for deinking surface-printed plastic films. U.S. Patent No. 9,616,595 further discloses the steps of grinding, deinking, general washing, washing solution recovery, pigment recovery, and drying. The deinking step involves the use of a high-pH aqueous washing fluid, a selective cleaning agent such as dodecyl sulfate, and high turbulence. This method claims the ability to remove surface-printed ink, which can contribute to chemical contamination after heating in the recycling process. This process is limited in its ability to remove bulk contaminants due to their limited solubility in the aqueous washing medium and / or their limited diffusibility into the plastic.

[0013] To overcome the fundamental limitations of mechanical recycling, numerous methods have been developed to purify contaminated polymers using a chemical approach (chemical recycling). Many of these methods use solvents to decontaminate and purify the polymer. The use of solvents allows for the extraction of impurities and dissolution of the polymer, which in turn allows for alternative separation techniques. For example, U.S. Patent No. 7,935,736 describes a method for recycling polyester from polyester-containing waste using a solvent to dissolve the polyester prior to cleaning. U.S. Patent No. 7,935,736 further describes the need to recover the polyester from the solvent using precipitation.

[0014] U.S. Patent No. 6,555,588 describes a method for producing polypropylene blends from plastic mixtures containing other polymers. U.S. Patent No. 6,555,588 describes extracting contaminants from a polymer in a selected solvent (e.g., hexane) at a temperature below the polymer's dissolution temperature for a predetermined residence time. U.S. Patent No. 6,555,588 further describes increasing the temperature of the solvent (or second solvent) to dissolve the polymer before filtration. U.S. Patent No. 6,555,588 also further describes using shear or flow to precipitate polypropylene from solution. The polypropylene blend described in U.S. Patent No. 6,555,588 contained up to 5.6% by weight of polyethylene contamination.

[0015] European Patent Application No. 849,312 (translated from German to English) describes a process for obtaining purified polyolefins from polyolefin-containing plastic mixtures or polyolefin-containing waste. European Patent Application No. 849,312 describes the extraction of polyolefin mixtures or waste containing hydrocarbon fractions of gasoline or diesel fuel with a boiling point above 90° C. at temperatures between 90° C. and the boiling point of the hydrocarbon solvent. European Patent Application No. 849,312 further describes the removal of foreign components from the hot polyolefin solution by contacting the solution with bleaching clay and / or activated carbon. European Patent Application No. 849,312 further describes cooling the solution to a temperature below 70°C to crystallize the polyolefin, and then removing the deposited solvent by heating the polyolefin above its melting point, or evaporating the deposited solvent under reduced pressure, or passing a gas stream through the polyolefin precipitate, and / or extracting the solvent with an alcohol or ketone boiling below the melting point of the polyolefin.

[0016] U.S. Patent No. 5,198,471 describes a method for separating polymers from a physically intermixed solid mixture containing multiple polymers (e.g., waste plastics) using a solvent at a first low temperature to form a first single-phase solution and a remaining solid component. U.S. Patent No. 5,198,471 further describes heating the solvent to a higher temperature to dissolve additional polymers that were not solubilized at the first, lower temperature. U.S. Patent No. 5,198,471 describes filtering the insoluble polymer component.

[0017] U.S. Patent No. 5,233,021 describes a method for extracting pure polymer components from multi-component structures (e.g., waste carpet) by dissolving each component in a supercritical fluid under appropriate temperature and pressure, and then varying the temperature and / or pressure to sequentially extract specific components. However, like U.S. Patent No. 5,198,471, U.S. Patent No. 5,233,021 only describes filtering the precipitated components.

[0018] U.S. Patent No. 5,739,270 describes a method and apparatus for continuously separating polymer components of plastics from contaminants and other components of the plastic using a co-solvent and a working fluid. The co-solvent at least partially dissolves the polymer, and a second fluid (which is liquid and in a critical or supercritical state) solubilizes the polymer components, causing some of the dissolved polymer to precipitate from the co-solvent. U.S. Patent No. 5,739,270 further describes a process for removing particulate contaminants, such as glass particles, by filtering the thermoplastic co-solvent (with or without a working fluid).

[0019] U.S. Patent No. 5,368,796 discloses a method for surface cleaning of polyethylene film. It further discloses the steps of shredding, a first surface cleaning step (using a boiling solvent at or near the melting temperature of polyethylene and under vigorous mechanical agitation for 30 minutes to scrape off the ink), a second surface cleaning step (using fresh solvent below the melting temperature of polyethylene and under vigorous mechanical agitation for 30 minutes), a third surface cleaning step (using a solvent below the melting temperature of polyethylene and under vigorous mechanical agitation for 30-60 minutes, followed by devolatilization), and melt densification. Optionally, the method may include a water wash step to remove surface mud before solvent treatment. U.S. Patent No. 5,368,796 further discloses that solvent washing achieves extraction in which the solvent does not dissolve the polymer. However, small amounts of wax, typically less than 1% by weight, may be removed. The solvent washing and extraction steps are further disclosed as being performed at the boiling point of the solvent, selected to be below the softening point of the polyethylene to avoid agglomeration. The above methods focus on removing surface printed inks and do not address the removal of bulk permeable contaminants as previously mentioned.

[0020] U.S. Patent Application No. 2009 / 0178693 discloses a method for purifying plastics. U.S. Patent Application No. 2009 / 0178693 further discloses a multi-step process including granulation 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), a final surface washing with supercritical CO2 to remove the high-boiling point solvent on the surface, and devolatilization. It further discloses that the plastic chip raw material is agitated with a solvent and that the chip shape is maintained. It also discloses that the recovered material remains as chips, meaning that the process is completed at a temperature below the primary melting point of the plastic.

[0021] U.S. Patent No. 9,834,621 discloses a method for purifying polypropylene, which comprises contacting recycled polypropylene with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of about 80°C to about 280°C and a pressure of about 10 atm to about 544 atm to produce extracted recycled polypropylene, dissolving the extracted recycled polypropylene in a solvent selected from the group consisting of the first fluid solvent, a second fluid solvent, and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a first solution containing polypropylene, at least one dissolved contaminant, and at least one suspended contaminant, and then heating the first solution at a temperature of about 90°C to about 280°C. and precipitating 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 second solution containing polypropylene, at least one dissolved contaminant, and a lesser amount of at least one suspended contaminant; filtering the second solution at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a third solution containing higher purity polypropylene, at least one dissolved contaminant, and an even lower amount of at least one suspended contaminant; and separating the higher purity polypropylene from the third solution, wherein the second fluid solvent has the same or a different chemical composition as the first fluid solvent. The above method is well suited to removing contaminants. However, the ability to dissolve, precipitate, and filter plastics can be very challenging and may not be suitable or practical for high molecular weight (MW) plastics, such as those used in film and blow-molded containers. Furthermore, the above methods do not mention removing surface contamination prior to extraction and dissolution, thus increasing the burden of such disclosed processes, particularly filtration.

[0022] In summary, known solvent-based methods for purifying contaminated plastics, such as those described above, do not address the problem of removing both surface and bulk contaminants from plastics efficiently enough to enable their use in demanding applications, particularly film and rigid applications involving high MW plastics, and therefore do not produce "virgin" polymers. Furthermore, these methods often result in co-dissolution of other polymers, and therefore cross-contamination. When adsorbents are used, filtration and / or centrifugation steps are often used to remove the spent adsorbent from the solution. Additionally, separation processes for solvent removal, such as heating, vacuum evaporation, and / or precipitation using a precipitating agent, are used to produce polymers free of residual solvent. [Prior art documents] [Patent documents]

[0023] [Patent Document 1] U.S. Patent No. 10,022,725 [Patent Document 2] U.S. Patent No. 9,616,595 [Patent Document 3] U.S. Patent No. 7,935,736 [Patent Document 4] U.S. Patent No. 6,555,588 [Patent Document 5] European Patent Application No. 849,312 [Patent Document 6] U.S. Patent No. 5,198,471 [Patent Document 7] U.S. Patent No. 5,233,021 [Patent Document 8] U.S. Patent No. 5,739,270 [Patent Document 9] U.S. Patent No. 5,368,796 [Patent Document 10] U.S. Patent Application No. 2009 / 0178693 [Patent Document 11] U.S. Patent No. 9,834,621 [Non-patent literature]

[0024] [Non-Patent Document 1] SMAl-Salem, P. et al., Waste Management, 29(10)(2009), 2625-2643 Summary of the Invention [Problem to be solved by the invention]

[0025] Therefore, there is a need for an improved solvent-based process for purifying contaminated recycled polymer that 1) uses a solvent that is easily and economically removed from the polymer; 2) efficiently removes both surface and bulk contamination; 3) is easy and simple in terms of the number of unit operations; 4) can be used for high MW plastics such as those resulting from film and rigid applications; 5) produces polymer without significant amounts of polymer cross-contamination; and 6) produces polymer that is virtually virgin (i.e., has properties similar to virgin polymer and is essentially contaminant-free, colorless, odorless, etc.). [Means for solving the problem]

[0026] In an embodiment of the present invention, a method for purifying recycled polymer is disclosed, the method comprising: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer comprising contaminants, each contaminant having a concentration, the contaminants of the recycled polymer being at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs). b) leaching the recycled polymer with a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm, for a total residence time and for each residence time of the leaching stages, to obtain a leaching solution containing at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, with an average removal efficiency, in multiple leaching stages, each having a concentration of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs. producing a leached polymer comprising at least one of phenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, wherein the leached polymer has an average removal efficiency of greater than about 55%; and c) extracting the leached polymer with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of about 80°C to about 280°C and a pressure of about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa), to produce an extracted polymer. d) dissolving the extracted 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; and e) heating 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).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 the filtered polymer, at least one dissolved contaminant, and an even lesser amount of at least one suspended contaminant; g) filtering the third 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). a) filtering by adsorptive filtration under pressure to produce a fourth solution containing filtered polymer; and h) separating the filtered polymer from the fourth solution to produce a higher purity polymer with an average removal efficiency, the higher purity polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, each having a concentration, wherein the second fluid solvent has the same or a different chemical composition as the first fluid solvent, and the higher purity polymer has an average removal efficiency of greater than about 75%.

[0027] In an embodiment of the present invention, a method for purifying recycled polymer is disclosed, the method comprising: a) obtaining recycled polyethylene, the recycled polyethylene being post-consumer recycled (PCR) polyethylene, the recycled polyethylene containing contaminants, each contaminant having a concentration, the contaminants of the recycled polymer including at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs); b) surface-washing the recycled polymer in a non-densified state to produce a surface-washed polymer, the surface-washing resulting in a reduction of loosely bound surface contaminants by greater than about 80%; and c) removing the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs from the recycled polymer at a temperature of about 55° C. to about 65° C. and atmospheric pressure with an average removal efficiency. leaching the leached polymer with ethyl acetate at a temperature of about 160°C and a pressure of about 3,000 psig (20.7 MPa) for a total residence time in a countercurrent auger extraction to produce a leached polymer containing at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, each having a concentration, wherein the average removal efficiency of the leached polymer is greater than about 90%; d) extracting the leached polymer with normal butane at a temperature of about 160°C and a pressure of about 3,000 psig (20.7 MPa) to produce an extracted polymer; e) dissolving the extracted polymer in normal butane at a temperature of about 160°C and a pressure of about 4,700 psig (32.4 MPa) to produce a first solution containing dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; and f) suspending the first solution at a temperature of about 160°C and a pressure of about 4,700 psig (32.4 MPa).g) filtering the second solution by mechanical filtration at a temperature of about 160°C and a pressure of about 4,700 psig (32.4 MPa) to produce a third solution comprising the filtered polymer, the at least one dissolved contaminant, and an even lesser amount of the at least one suspended contaminant; h) filtering the third solution by mechanical filtration at a temperature of about 160°C and a pressure of about 4,700 psig (32.4 MPa) to produce a third solution comprising the filtered polymer, the at least one dissolved contaminant, and an even lesser amount of the at least one suspended contaminant; and j) filtering the third solution by mechanical filtration at a temperature of about 160°C and a pressure of about 4,700 psig (32.4 MPa) to produce a third solution comprising the filtered polymer, the at least one dissolved contaminant, and an even lesser amount of the at least one suspended contaminant. filtering by adsorptive filtration by contacting with a medium to produce a fourth solution containing the twice-filtered polymer; and i) separating the filtered polymer from the fourth solution to produce a higher purity polymer with an average removal efficiency, the higher purity polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, each having a concentration, wherein the higher purity polymer has an average removal efficiency of greater than about 95%. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1 is a block flow diagram illustrating the main steps of one embodiment of the present invention. [Figure 1B] FIG. 2 is a block flow diagram illustrating the major steps of another embodiment of the present invention. [Figure 2] 1 is a calibration curve for calculating polyethylene content in polypropylene using enthalpy values ​​measured by DSC. [Figure 3A] FIG. 1 is a schematic diagram of the experimental setup used in the extraction step of the dissolution recycling process. [Figure 3B] FIG. 1 is a schematic diagram of the experimental equipment used in the dissolution, precipitation, filtration, and separation steps of the dissolution recycling process. [Figure 4]Figures 4-1 to 4-3 are tables showing removal data from the dissolution recycle process only, the immersion leaching process only, and the combined immersion leaching and dissolution recycle process. DETAILED DESCRIPTION OF THE INVENTION

[0029] I. Definition As used herein, the term "plastic" refers to polymers such as polyethylene (PE), PP, PET, LLDPE, LDPE, HDPE, polyethylene copolymers, ethyl vinyl acetate copolymer (EVA), ethyl vinyl alcohol copolymer (EVOH), ethylene acrylic acid copolymer (EAA), PS, PC, PVC, styrene butadiene styrene (SBS), PA, etc., or mixtures thereof. Polymers such as these are generally characterized by a high MW, which determines their melt processability and solid-state mechanical properties. For purposes of this invention, the terms "polymer" and "plastic" are used interchangeably, and the term "MW" refers to the weight average molecular weight of a polymer.

[0030] As used herein, the term "recycled polymer" refers to a polymer that has previously been used for some purpose and then recovered for further processing.

[0031] As used herein, the term "post-consumer" refers to a source of a material that originates after an end-user has used the material in a consumer good or consumer product.

[0032] As used herein, the term "post-consumer reclaimed" (PCR) refers to materials that are produced after an end-consumer has used the material and disposed of it in a waste stream.

[0033] As used herein, the term "post-industrial reclaimed" (PIR) refers to the source of materials that originate during the manufacture of a commodity or product and prior to its consumer use.

[0034] As used herein, the term "fluid solvent" refers to a substance that can exist in a liquid state under specified temperature and pressure conditions. In some embodiments, a fluid solvent may be a predominantly homogeneous chemical composition of one type of molecule or isomer, while in other embodiments, a fluid solvent may be a mixture of several different molecular compositions or isomers. Furthermore, in some embodiments of the present invention, the term "fluid solvent" may also apply to a substance that is at, near, or above its critical temperature and critical pressure (critical point). It is well known to those skilled in the art that when a substance exceeds its critical point, it is known as a "supercritical fluid," which does not have the typical physical properties (i.e., density) of a liquid.

[0035] As used herein, the term "dissolved" means at least partially incorporating a solute (polymeric or non-polymeric) into a solvent at the molecular level. Furthermore, the thermodynamic stability of a solute / solvent solution is determined by the following equation: ΔG mix =ΔH mix -TΔS mix where ΔG mix is the Gibbs free energy change of mixing of the solute with the solvent, and ΔH mix is the enthalpy change of mixing, T is the absolute temperature, and ΔS mix is the entropy of mixing. To maintain a stable solution of a solute in a solvent, the Gibbs free energy must be negative and minimal. Therefore, any combination of solute and solvent that minimizes the negative Gibbs free energy at the appropriate temperature and pressure can be used in the present invention.

[0036] As used herein, the term "normal boiling point" refers to the boiling temperature at an absolute pressure of exactly 100 kPa (1 bar, 14.5 psia, 0.9869 atm) as established by the International Union of Pure and Applied Chemistry (IUPAC).

[0037] As used herein, the term "standard enthalpy change of vaporization" refers to the enthalpy change required for a given amount of a substance to change from a liquid to a vapor at the normal boiling point of that substance.

[0038] As used herein, the term "polymer solution" refers to a solution in which a polymer is dissolved in a solvent. Because a polymer solution may contain undissolved material (e.g., at least one suspended contaminant), a polymer solution may also be a "slurry" of undissolved material suspended in a solution of polymer dissolved in a solvent.

[0039] As used herein, the terms "sedimentation" and "precipitation" are used interchangeably and refer to the tendency of particles in a suspension to separate from a liquid in response to a force acting on the particles (typically gravity).

[0040] As used herein, the term "suspended contaminants" refers to undesirable or unwanted constituents present throughout the bulk of a heterogeneous mixture medium.

[0041] As used herein, the term "dissolved contaminants" refers to undesirable or unwanted constituents that are at least partially incorporated into the solvent at the molecular level.

[0042] As used herein, the terms "filtration" and "filtering" refer to the separation of at least one dissolved and / or suspended contaminant from a fluid by using mechanical and / or physical operations (e.g., passing the contaminated fluid through a filtration system). As used herein, the terms "filtration system" and "filter" are used interchangeably.

[0043] The term "low suspended contaminants" as used herein in reference to a solution refers to the state of the solution subsequent to a previous condition (e.g., prior to a contaminant removal step), where the previous solution had a relatively high amount of suspended contaminants.

[0044] As used herein, the term "containing even less suspended contaminants" in reference to a solution refers to a state of the solution subsequent to a previous condition (e.g., "containing less suspended contaminants"), where the previous solution had a relatively higher amount of suspended contaminants.

[0045] As used herein, the terms "solid medium" and "solid media" refer to materials that exist in a solid state under conditions of use. The solid medium may be crystalline, semicrystalline, or amorphous. The solid medium may be granular and may be supplied in different shapes (i.e., spheres, cylinders, pellets, etc.). When the solid medium is granular, the particle size and particle size distribution of the solid medium may be defined by the mesh size used to classify the granular medium. An example of standard mesh size designation 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 may also be a nonwoven fiber mat or a woven fabric.

[0046] As used herein, the term "higher purity polymer solution" refers to a polymer solution that has a lower amount of one or more contaminants compared to the same polymer solution prior to a purification step.

[0047] As used herein, the term "extraction" refers to the act of transporting a solute species from a liquid phase (or solid matrix) across a phase boundary into a separate immiscible liquid phase. The driving force(s) for extraction are explained by partition theory.

[0048] As used herein, the term "extracted" refers to a material that has a reduced amount of one or more solute species compared to the same material prior to the extraction process. As used herein, the term "extracted regenerated polymer" refers to a regenerated polymer that has a reduced amount of one or more solute species compared to the same regenerated polymer prior to the extraction process.

[0049] As used herein, the term "like virgin" means essentially free of contaminants, colorless, odorless, homogeneous, and similar in properties to virgin polymer.

[0050] As used herein, the term "copolymer of predominantly polypropylene" refers to a copolymer having greater than 70 mol % propylene repeat units.

[0051] As used herein, the term "copolymer of predominantly polyethylene" refers to a copolymer having greater than 70 mol % ethylene repeat units.

[0052] As used herein, any reference to international units of pressure (e.g., MPa) refers to gauge pressure.

[0053] As used herein, the term "axial flow direction" refers to fluid flowing parallel to the longitudinal axis of the filter media.

[0054] As used herein, the term "radial flow direction" refers to fluid flowing perpendicular to the longitudinal axis of the filter media.

[0055] As used herein, the term "candle filter" refers to a device that uses pressure to separate solids from liquids. For a detailed description of candle filters, as well as other solid-liquid separation devices, see the following reference: Perry, Robert H, and Don W. Green. Perry's Chemical Engineers' Handbook. New York: McGraw-Hill, 2008.

[0056] As used herein, the term "pre-coated with filter aid" refers to a solid-liquid separation device in which the filter medium is composed of a rigid or semi-rigid screen upon which one or more layers of finely divided solid material (e.g., diatomaceous earth, perlite, cellulose fiber, clay, activated carbon, alumina, silica, alumina silicates, zeolites, and mixtures thereof) are deposited.

[0057] As used herein, the term "body feeding" refers to adding a filter aid to a fluid before the fluid is filtered.

[0058] As used herein, the term "contaminant" refers to any undesirable substance contained on the surface of plastic or in the bulk of plastic. The term "chemical contaminant" refers to any undesirable chemical species on the surface of plastic or in the bulk of plastic, including the molecular or elemental composition of the contaminant. These terms may be used interchangeably depending on the intent. For example, paper contamination contains cellulose; that is, cellulose is one type of chemical contaminant in paper contamination.

[0059] 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 classified into classes that include chemical contaminants with similar chemical structures. For example, As, Hg, and Cr are chemical contaminants in the "heavy metals" classification. Each contaminant may have different chemical attributes, such as solubility and diffusibility in plastics, as well as target levels depending on concentration and end-use market.

[0060] As used herein, the term "surface contaminants" refers to contaminants present on the surface of plastic. Similarly, the term "surface chemical contaminants" refers to the molecular or elemental composition of the surface contaminants. Surface contaminants may adhere to the surface of plastic loosely through physical attraction or more strongly through polar or other forces. Generally, surface contaminants have less than about 80% of their surface area embedded in the plastic.

[0061] As used herein, the term "bulk contaminant" refers to a contaminant present in the bulk of the plastic. Similarly, the term "bulk chemical contaminant" refers to the molecular or elemental composition of the bulk contaminant. Generally, a bulk contaminant has about 80% or more of its surface area embedded in the plastic.

[0062] As used herein, the terms "surface contamination" and "surface chemical contamination" refer to the sum of all surface contaminants and the sum of all surface chemical contaminants, respectively.

[0063] As used herein, the terms "bulk contamination" and "bulk chemical contamination" refer to the sum of all bulk contaminants and the sum of all bulk chemical contaminants, respectively.

[0064] As used herein, the term "total contamination" refers to the sum of surface contamination and bulk contamination, and the sum of all surface chemical contamination and bulk chemical contamination, respectively.

[0065] As used herein, the term "permeable contaminant" refers to a chemical contaminant that is soluble and diffusible in plastic. Non-limiting examples of permeable contaminants are formaldehyde, bisphenol A, and naphthalene.

[0066] As used herein, the term "impermeable contaminant" refers to a chemical contaminant that is either insoluble or non-diffusible in plastic. Non-limiting examples of impermeable contaminants are heavy metals and gel particles composed of cross-linked or ultra-high MW plastic (too large to diffuse).

[0067] As used herein, the term "permeable contamination" refers to the sum of all permeable contaminants, and the term "impermeable contamination" refers to the sum of all impermeable contaminants. The sum of all permeable contamination and impermeable contamination is a "chemical contamination" when described in molecular or elemental terms, but is simply a "contamination" when described in general terms (such as cellulose vs. paper).

[0068] As used herein, the term "intentional contaminant" refers to a contaminant that is intentionally added by a manufacturer, retailer, or supply chain for a specific purpose that benefits the consumer, but that may be undesirable in recycled plastics. Examples include printing, paper labels, label adhesives, pigments (such as TiO), processing additives (such as antioxidants - AO), etc., necessary for marketing, branding, processability, and / or end-use performance. As used herein, the term "intentional chemical contaminant" refers to an intentional contaminant represented by its chemical composition. As used herein, the term "intentional contamination" refers to the sum of all intentional contaminants, and the term "intentional chemical contamination" refers to the sum of all intentional contaminants represented by their chemical composition.

[0069] As used herein, the surface area to volume ratio of a plastic is calculated as follows: For generally spherical objects such as pellets, crushed pellets, and pulverized pellets, the surface area to volume ratio is calculated by 3 / r, where r is the mass mean radius. For generally flat, thin objects such as films, the surface area to volume ratio is calculated by 2 / t, where t is the mass mean thickness. For generally long, cylindrical objects such as fibers, the surface area to volume ratio is calculated by 2 / r, where r is the mass mean radius. For purposes of this invention, the terms "mass mean surface area to volume ratio" and "surface area to volume ratio" are used interchangeably.

[0070] As used herein, the term "unintentional contaminant" refers to any contaminant that is not intentionally added. Examples include dirt and cross-contamination that is not intentionally added by the manufacturer, retailer, or consumer. As used herein, the term "unintentional chemical contaminant" refers to an unintentional contaminant represented by its chemical composition. As used herein, the term "unintentional contamination" refers to the sum of all unintentional contaminants, and the term "unintentional chemical contamination" refers to the sum of all unintentional contaminants represented by their chemical composition.

[0071] As used herein, the term "densified" refers to a state of plastic in which the bulk density of the plastic is higher than the bulk density of the original / pre-densified plastic and the original surface of the plastic has been reduced and / or made inaccessible to wetting fluids. The process of producing densified materials is called densification.

[0072] As used herein, the term "melt densification" refers to densification that occurs near, at, or above the primary melting point of a plastic. Non-limiting methods of melt densification include melt extrusion and coalescence using equipment such as a Herbold HV series plastocompactor.

[0073] As used herein, the term "primary melting point" refers to the peak melting point (the largest endothermic peak above a zero-slope baseline) of a plastic as measured using Differential Scanning Calorimetry (DSC). For purposes of the present invention, the terms "primary melting point," "melting point," "melting temperature," and "primary melting temperature" are used interchangeably. For amorphous materials and / or materials lacking a distinct melting point, the specified temperature is the approximate softening point of the material, which may be best characterized by its glass transition temperature. Those skilled in the art will understand the relevance of the criteria for non-semicrystalline materials.

[0074] As used herein, the term "hexane" refers to a blend of hexane isomers such as normal hexane (at least 45% by volume, typically about 53% by volume), isohexane (2-methylpentane, 3-methylpentane, and 2,3-dimethylbutane), and neohexane (2,2-dimethylbutane).

[0075] As used herein, the term "limit of quantitation" or "LOQ" refers to the limit of detection for a given chemical contaminant as determined by the analytical methods disclosed in Section IX. The LOQ is a function of the method used and may vary from test method to test method. The LOQ used herein is specific to the method listed in Section IX.

[0076] As used herein, the term "removal efficiency" refers to the efficiency of a process to remove a particular contaminant, calculated as 100 × (initial concentration - final concentration) / initial concentration and expressed as a percentage. If the final concentration is lower than the LOQ, the removal efficiency is considered 100% for simplicity. Higher purity plastics may have higher levels of contaminants than recycled polymers due to 1) measurement error, 2) contaminant hot and cold spots in the recycled polymer, and 3) external contamination during sampling. In such cases, the removal efficiency is set to 0% to avoid biasing the average results. If such an occurrence occurs consistently in a given process, it is more likely to be due to the process and should be investigated more closely, but this was not generally the case for the process of the present invention. As used herein, the term "average removal efficiency" refers to the average removal efficiency of each contaminant.

[0077] For purposes of the present invention, the terms "purification process" and "dissolution recycle process" are used interchangeably. Also, for purposes of the present invention, the terms "step" and "process step" are used interchangeably.

[0078] As used herein, the word "or", when used as a conjunction of two or more elements, means to include the elements individually as well as in any combination, e.g., X or Y means either X or Y, or both.

[0079] As used herein, articles such as "a" and "an" are understood to mean one or more of the material claimed or described.

[0080] II. Recycled Polymers Polymers at their initial manufacturing stage (virgin polymers) at resin suppliers such as Dow, Nova, and ExxonMobil contain very little contamination, but during the polymer's life cycle (from manufacturing to distribution, consumer use, and eventual recycling), contamination is introduced, intentionally or unintentionally.

[0081] Non-limiting examples of intentional contamination include surface printing, paper labels, label adhesives, pigments (such as TiO), processing additives (such as AO), and the like, necessary for marketing, branding, processability, and / or end-use performance. Non-limiting examples of unintentional contamination include dirt, cross-contamination, certain heavy metals, pesticides, dioxins, furans, PCBs, and the like. Unintentional contamination can also result from reactions involving intentional contaminants, such as the oxidation of paper labels to dioxins or the decomposition of adhesives or printing binders. Most of the latter occurs during melt densification methods used in recycling processes. Furthermore, oxidation of plastics during melt processing steps, such as those used in the original packaging or product creation and / or recycling of the latter, generates unintentional contamination, such as gels. In addition, 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), and the like, can be contaminated with such products. Finally, unintentional contamination can be introduced into the plastic during manufacturing, such as contamination of the plastic with reaction by-products, unreacted monomers, etc.

[0082] It is recognized that different recycled polymer sources have different contamination and associated risks. While there are large amounts of recycled polymer streams with unknown origins and life cycles, it is clear that the potential for contamination is also very high. On the other hand, controlled recycled polymer streams are available and pose a lower potential risk to demanding applications. For example, if a recycled polymer stream is known to be from a demanding application, it will likely be free of undesirable contaminants until distribution to consumers; otherwise, these plastics would not be approved for use in these applications. Therefore, contamination that prevents reuse in these same applications will primarily be unintentional contamination that originates from external sources and enters the plastic through surface contamination. Small amounts of contamination may result from reactions involving intentional contamination, such as the oxidation of cellulosic materials to dioxins during melt densification.

[0083] Pre-consumer plastics generally have very low levels of contamination due to their known composition and controlled history. While pre-consumer plastics may contain intentional contaminants such as surface printing and opacifiers, these are known and controlled, making it very easy to find applications that tolerate such known contaminants. Furthermore, pre-consumer plastics tend to have a low amount of unintentional contamination because their controlled history prevents external contamination. Therefore, pre-consumer plastics originally intended for use in demanding applications are an ideal source of recycled polymers for the same end markets with minimal cleaning / purification. The latter pre-consumer plastics in the form of films are called "Approved Sourced Post-Industrial Film" (ASPIF). The disadvantage is that the ASPIF stream is in very limited supply and does not maintain circularity.

[0084] Post-consumer plastics are generally more contaminated than pre-consumer plastics. The post-consumer subclass of post-consumer plastics has the second lowest contamination level after pre-consumer recycled plastics, given their reasonably controlled life cycle within the commercial supply chain. Post-consumer recycled plastics generally have known and controlled levels of intentional contamination, thus enabling widespread use as recycled polymers. However, unintentional contamination is known to be ubiquitous, causing problems in this stream and preventing widespread use in demanding applications. Post-consumer plastics sourced from demanding applications can potentially be returned to these fields and reused after appropriate cleaning / purification. Post-consumer plastics sourced from demanding applications in the form of film are referred to as "Approved Source Post-Commercial Film" (ASPCF). To address the ongoing need for higher-purity recycled polymers, recycled material suppliers have recently introduced post-consumer film sources with more controlled and known histories. These new sources are referred to as high-custody sources and are primarily used in the post-consumer film stream. That is, highly controlled post-market film supplies should have reduced levels of contamination compared to typical post-market film supplies. Disadvantages: these highly controlled supplies have limited capacity and are more expensive.

[0085] The post-consumer / post-home subclass has very high levels of contamination, given its uncontrolled life cycle within commercial channels. Such plastics have high levels of both intentional and unintentional contamination that are highly variable, unknown, and uncontrolled. Such plastics may contain plastic sources that were not originally acceptable for use in demanding applications. As such, the market for this plastic source is limited and essentially nonexistent in demanding applications.

[0086] Surprisingly, the higher purity plastics of the present invention may enable the broader use of plastics sourced from post-industrial (both ASPIF and uncontrolled sources), post-commercial (both ASPCF and uncontrolled sources), and post-household plastics in demanding applications with certain limitations. Additionally, most recycled material customers are seeking higher purity materials beyond what is available today, and the higher purity plastics of the present invention fulfill this broader need for higher purity plastics from all sources.

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

[0088] The recycled polymer can be a plastic of a first age (used only once before entering the recycled polymer stream), a plastic of a second age (used twice before entering the recycled polymer stream), or a plastic of an older age (used many times before entering the recycled polymer stream). In an embodiment of the invention, the recycled polymer comprises virgin plastic. In an embodiment of the invention, the recycled polymer comprises a film. In an embodiment of the invention, the recycled polymer is selected from the group comprising 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 an embodiment of the invention, the recycled polymer comprises regrind / offcut / post-industrial plastic. In an embodiment of the invention, the recycled polymer comprises PIR polymer. In an embodiment of the invention, the recycled polymer comprises PIR polymer film. In an embodiment of the invention, the recycled polymer comprises PIR polymer nonwoven. In an embodiment of the invention, the PIR polymer film is ASPIF. In an embodiment of the invention, the recycled polymer comprises PCR polymer. In an embodiment of the invention, the recycled polymer comprises PCR polymer film. In an embodiment of the invention, the recycled polymer comprises PCR polymer nonwoven. In an embodiment of the invention, the PCR polymer film is ASPCF. In an embodiment of the invention, the recycled polymer comprises high-quality PCR polymer film. In an embodiment of the invention, the recycled polymer comprises post-consumer polymer. In an embodiment of the invention, the recycled polymer comprises post-consumer polymer film. In an embodiment of the invention, the recycled polymer comprises post-consumer polymer nonwoven.

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

[0091] In an embodiment of the present invention, the recycled polymer is a PCR polymer. In an embodiment of the present invention, the recycled polymer is a polypropylene homopolymer or a predominantly polypropylene copolymer. In an embodiment of the present invention, the recycled polymer is a polyethylene homopolymer or a predominantly polyethylene copolymer. In an embodiment of the present invention, a method for purifying a recycled polymer includes obtaining a recycled polymer, wherein the recycled polymer is selected from the group consisting of a PCR polymer, a PIR polymer, and combinations thereof. The recycled polymer may be in many forms, including, but not limited to, pellets, pulverized pellets, crushed pellets, shredded film, chopped or crushed injection molded parts, chopped or crushed blow molded parts, thermoformed parts, chopped nonwoven or woven fabric, extruded strands, or agglomerated particles. In an embodiment of the present invention, the recycled polymer comprises pellets.

[0092] In an embodiment of the present invention, the recycled polymer is about 1 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of about 5 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of about 20 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of about 50 mm -1 The average surface area to volume ratio is greater than 1000 .mu.m.

[0093] For purposes of this invention, recycled polymers originate from post-consumer, post-industrial, post-consumer, and / or other specialized recycled waste streams. For example, PCR polymers may originate from curbside recycled streams, where end consumers deposit used polymer from packaging and products in designated receptacles for collection by waste haulers or recyclers. PCR polymers may also originate from in-store "return" programs, where consumers bring waste polymer to stores and deposit it in designated collection receptacles. An example of a PIR polymer may be waste polymers (i.e., scraps, off-spec materials, starting materials) generated during the manufacture or transportation of goods or products that are collected by manufacturers as unusable materials. One example of a waste polymer from a specialized waste stream may be waste polymers derived from the recycling of electronic waste (also known as e-waste). Another example of a waste polymer from a specialized waste stream may be waste polymers derived from automobile recycling. Another example of a waste polymer from a specialized waste stream may be waste polymers derived from post-consumer carpet and fabric recycling.

[0094] For purposes of this invention, recycled polymers are homogeneous compositions of individual polymers or mixtures of different polymer compositions. Non-limiting examples of recycled polymer compositions include polyolefin homopolymers and copolymers such as polyethylene and isotactic polypropylene, polyesters such as poly(ethylene terephthalate), vinyl polymers such as poly(vinyl 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 poly(dimethylsiloxane), thermoplastic elastomers such as styrene-butadiene block copolymers and ethylene-propylene rubber, and other soluble polymers that may be apparent to those skilled in the art.

[0095] Recycled polymers may also contain various pigments, dyes, processing aids, stabilizers, fillers, and other performance-enhancing additives that were added to the polymer during polymerization or conversion of the original polymer into the final form of the article. Non-limiting examples of pigments include organic pigments (e.g., copper phthalocyanine), inorganic pigments (e.g., titanium dioxide), and other pigments as would be apparent to one skilled in the art. A non-limiting example of an organic pigment is Basic Yellow 51. Non-limiting examples of processing aids include antistatic agents (e.g., glycerol monostearate) and lubricity enhancers (e.g., erucamide). A non-limiting example of a stabilizer is octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate. Non-limiting examples of fillers include calcium carbonate, talc, and glass fiber.

[0096] III. Contaminants Contaminants can generally be classified into two migration categories: 1) permeable; and 2) impermeable. Permeable contaminants have solubility and diffusivity in the recycled polymer, allowing them to migrate into, through, and out of the polymer due to chemical potential gradients. In other words, the group referred to as permeable contaminants and permeable contamination is mobile. Impermeable means that the contaminant does not have sufficient solubility and diffusivity to significantly migrate into, through, and out of the polymer. In other words, impermeable contamination, represented by the sum of all impermeable contaminants, is essentially immobile. That is, once impermeable contamination is initially deposited, it remains in place until it is physically removed, transported by convection, or brought into contact with a different material that is permeable to the contaminant.

[0097] Chemical contaminants in recycled polymers can be numerous but generally fall into one of several relevant chemical classes. Non-limiting examples of relevant chemical classes are pesticides, aldehydes, allergenic fragrances, izioalines, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, organotins, metals, phthalates, and polyaromatic hydrocarbons (PAHs). Only a portion of these chemical classes are routinely found in pre- and post-consumer recycled polymers, such as pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, metals, organotins, phthalates, and PAHs.

[0098] Using the analytical methods disclosed in Section IX, the LOQs for various contaminants can vary by orders of magnitude. For example, a typical pesticide has an LOQ of about 10 ppb. A typical alkylphenol ethoxylate has an LOQ of about 50 ppb. A typical alkylphenol has an LOQ of about 5 ppb. A bisphenol A has an LOQ of about 5 ppb. A typical dioxin has an LOQ of about 0.2 ppt. A typical furan has an LOQ of about 0.2 ppt. A typical PCB has an LOQ of about 5 ppt. A typical heavy metal has an LOQ of about 100 ppb. A typical organotin has an LOQ of about 300 ppt. A typical phthalate has an LOQ of 50 ppb. A typical PAH has an LOQ of 1 ppb.

[0099] As shown in Tables 1a-1i, several film sources were broadly classified for chemical contamination using the analytical methods disclosed in Section IX, including three ASPIF sources, three highly controlled post-market film sources, three post-market film sources, and one post-home film source. To simplify the presentation of chemical contamination results, concentration data are presented as LOQs rather than absolute weight fractions. For example, if the contaminant concentration is 10 ppm and the LOQ is 1 ppm, the concentration displayed in the data table is 10 x LOQ, or exactly 10. Also, "dnt" stands for "not tested."

[0100] Table 1a~Table 1i Chemical contamination of ASPIF, highly controlled post-market (HCPC), post-market (PC), and post-home use (PH) film sources

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3]

[0104] [Table 4]

[0105] [Table 5]

[0106] [Table 6]

[0107] [Table 7]

[0108] [Table 8]

[0109] [Table 9]

[0110] The ASPIF sources tested were essentially free of detectable levels of chemical contaminants, with the exception of alkylphenols and heavy metals, as well as small amounts of organotins and PAHs. The chemical contaminant results for these ASPIF sources serve as a guide to the levels of chemical contamination representative of these controlled end markets and demonstrate that heavy metals, which in any event have a low migration risk, are ubiquitous across all film sources. Therefore, heavy metals were excluded from the ongoing analysis in this application. The highly controlled post-market film sources tested contained few pesticides and alkylphenol ethoxylates, but contained detectable levels of alkylphenols, bisphenol A, dioxins / furans / PCBs, and PAHs, as well as low levels of phthalates. The post-market film sources tested were heavily contaminated with all classes evaluated; for example, dioxins were typically present at concentrations as high as 40x the LOQ, although one source contained dioxins at concentrations as high as 200x the LOQ. The post-consumer domestic sources tested were the most heavily contaminated, with concentrations of dioxins as high as 300x the LOQ and PCBs as high as 180x the LOQ.

[0111] Representative chemical species were selected from various classes based on their distribution across the spectrum of recycled polymer sources from Tables 1a-1i. The selected chemicals within these classes were piperonyl butoxide, representing pesticides; 4-t-octylphenol hexaethoxylate and isononylphenol triethoxylate, representing alkylphenols; isononylphenol and 4-tert-pentylphenol, 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; PCB105 and PCB118, representing PCBs; monobutyltin and dibutyltin, representing organotins; dibutyl phthalate and di-2-ethylhexyl phthalate, representing phthalates; and fluoranthene and phenanthrene, representing PAHs (Table 2).

[0112] In an embodiment of the present invention, the chemical contaminants in the recycled polymer include at least one chemical contaminant, wherein such chemical contaminant is selected from the group including pesticides, alkylphenols, alkylphenol ethoxylates, bisphenols, dioxins, furans, PCBs, phthalates, PAHs, or mixtures thereof.

[0113] In an embodiment of the present invention, the pesticide includes piperonyl butoxide, benzalkonium chloride (BAC), N,N-diethyl-meta-toluamide (DEET), and didecyldimethylammonium chloride (DDAC). In an embodiment of the present invention, the alkylphenol ethoxylate includes isononylphenol monoethoxylate, isononylphenol diethoxylate, isononylphenol triethoxylate, and isononylphenol tetraethoxylate. In an embodiment of the present invention, the alkylphenol includes isononylphenol, 4-tert-butylphenol, and 4-tert-pentylphenol. In an embodiment of the present invention, the bisphenol includes bisphenol A. In an embodiment of the present invention, the dioxin includes 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD, and OCDD. In an embodiment of the present invention, the furan includes OCDF. In an embodiment of the present invention, the PCBs include PCB77, PCB81, PCB126, PCB105, PCB114, PCB118, PCB123, PCB156, and PCB167. In an embodiment of the present invention, the phthalates include di-2-propylheptyl phthalate, diisobutyl phthalate, dibutyl phthalate, di-1-ethylhexyl phthalate, and diisononyl phthalate. In an embodiment of the present invention, the PAHs include acenaphthene, acenaphthylene, anthracene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[e]pyrene, benzo[ghi]perylene, chrysene, cyclopenta[cd]pyrene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene. In an embodiment of the present invention, the organotin compounds include monobutyltin, dibutyltin, and dioctyltin.

[0114] In an embodiment of the present invention, the contaminants in the recycled polymer may include 4-tert-pentylphenol. In an embodiment of the present invention, the contaminants in the recycled polymer may include bisphenol A. In an embodiment of the present invention, the contaminants in the recycled polymer may include OCDD. In an embodiment of the present invention, the contaminants in the recycled polymer may include PCB118. In an embodiment of the present invention, the contaminants in the recycled polymer may include di-2-ethylhexyl phthalate.

[0115] To simplify the presentation of purification results for the objects of the present invention and related examples, the number of chemical species presented per chemical category is limited to the aforementioned representative chemical species for each chemical category, as shown in Table 2, along with the associated LOQs and respective levels for the ASPIF sources tested. Even though more detailed and complete chemical analyses have been completed for all objects of the present invention, only selected chemicals are shown as ongoing. This simplification does not affect or alter the content of the present invention or the conclusions drawn therefrom. The selected chemicals appropriately and consistently represent broader classes with respect to purification.

[0116] [Table 10]

[0117] In an embodiment of the present invention, the concentration of each pesticide in the higher purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable pesticide. In an embodiment of the present invention, the concentration of bisphenol A in the higher purity plastic is lower than its respective LOQ, and the recycled polymer has at least detectable bisphenol A. In an embodiment of the present invention, the concentration of each dioxin in the higher purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable dioxin. In an embodiment of the present invention, the concentration of each PCB in the higher purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable PCB. In an embodiment of the present invention, the concentration of each phthalate in the higher purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable phthalate.

[0118] In an embodiment of the present invention, the concentration of piperonyl butoxide in the higher purity plastic is less than about 10 ppb, the recycled polymer has a piperonyl butoxide concentration greater than 10 ppb, the concentration of 4-tert-pentylphenol in the higher purity plastic is less than about 5 ppb, the recycled polymer has a 4-tert-pentylphenol concentration greater than 5 ppb, the concentration of bisphenol A in the higher purity plastic is less than about 5 ppb, and the recycled polymer has a bisphenol A concentration greater than 5 ppb. The concentration of OCDD in the higher purity plastics is less than about 0.2 ppt, the recycled polymer has an OCDD concentration greater than 0.2 ppt, the concentration of PCB118 in the higher purity plastics is less than about 10 ppt, the recycled polymer has a PCB118 concentration greater than 10 ppt, the concentration of di-2-ethylhexyl phthalate in the higher purity plastics is less than about 50 ppb, and the recycled polymer has a di-2-ethylhexyl phthalate concentration greater than 50 ppb.

[0119] In an embodiment of the invention, the removal efficiency of the piperonyl butoxide contaminant is greater than 55% and the concentration of piperonyl butoxide in the recycled polymer is at least 10 ppb. In an embodiment of the invention, the removal efficiency of the piperonyl butoxide contaminant is greater than 85% and the concentration of piperonyl butoxide in the recycled polymer is greater than about 10 ppb.

[0120] In an embodiment of the invention, the removal efficiency of 4-tert-pentylphenol contaminants is greater than 55% and the concentration of 4-tert-pentylphenol in the recycled polymer is at least 5 ppb. In an embodiment of the invention, the removal efficiency of 4-tert-pentylphenol contaminants is greater than 85% and the concentration of 4-tert-pentylphenol in the recycled polymer is at least 5 ppb.

[0121] In an embodiment 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 an embodiment 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.

[0122] 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.

[0123] In embodiments of the present invention, the OCDF contaminant removal efficiency is greater than 55% and the OCDF concentration in the recycled polymer is greater than about 0.2 ppt. In embodiments of the present invention, the OCDF contaminant removal efficiency is greater than 93% and the OCDF concentration in the recycled polymer is greater than about 0.2 ppt.

[0124] In embodiments of the invention, the removal efficiency of PCB118 contaminants is greater than 55% and the concentration of PCB118 in the recycled polymer is at least 10 ppt. In embodiments of the invention, the removal efficiency of PCB118 contaminants is greater than 66% and the concentration of PCB118 in the recycled polymer is greater than about 10 ppt.

[0125] In an embodiment of the invention, the removal efficiency of di-2-ethylhexyl phthalate contaminants is greater than 55%, and the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb. In an embodiment of the invention, the removal efficiency of di-2-ethylhexyl phthalate contaminants is greater than 78%, and the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb.

[0126] In an embodiment of the invention, the removal efficiency of the phenanthrene contaminant is greater than 55% and the concentration of phenanthrene in the recycled polymer is at least 1 ppb. In an embodiment of the invention, the removal efficiency of the phenanthrene contaminant is greater than 93% and the concentration of phenanthrene in the recycled polymer is at least 1 ppb.

[0127] Contamination can be located on the surface or in the bulk of plastics. Surface contamination is very simply and easily removed by surface cleaning techniques available on the market today. If surface contamination is permeable to plastics, it will become bulk contamination over time through diffusion mechanisms, thus complicating reduction and limiting the effectiveness of surface cleaning techniques. If surface contamination is impermeable to plastics, it will not diffuse into the bulk and will be reduced by simple surface cleaning methods such as aqueous cleaning. Bulk contamination, whether permeable or impermeable, often cannot be effectively removed by simple surface purification methods such as aqueous cleaning. Impermeable bulk contamination (also known as bulk impermeable contamination) can be trapped within the bulk plastic and released by mechanisms including melt convection, melt filtration, or dissolution / decomposition of the bulk plastic.

[0128] As previously mentioned, contamination can be introduced externally throughout the life cycle of a plastic. If the contamination is impermeable, it will remain largely on the surface throughout the plastic's life cycle, up until the point of recycling. If the contamination is permeable, it will migrate into the bulk plastic over time. Thus, in the absence of contamination or purification events, contamination will remain essentially constant, while the balance between surface and bulk contamination will vary over time but approach equilibrium over time. Generally, loosely bound surface contamination, such as mud, may be present at 0.01 to about 0.1 wt. %. Chemical contamination, particularly the chemical contaminants of concern in this invention, may be present at ppm, ppb, or even ppt levels.

[0129] Permeable and impermeable contaminants present different challenges in demanding applications. For example, permeable contaminants, whether in the bulk plastic or on the plastic surface, can migrate to uncontaminated materials such as products or to human skin. Therefore, if packaging contains permeable contaminants, such contaminants may migrate into the product, rendering it unsuitable for these demanding end markets. However, if the contaminant is impermeable and present in the bulk of the plastic, it has little ability to migrate to the product or to the user's skin unless the bulk plastic is degraded or ingested. Therefore, packaging may use this contaminated plastic material without risk of the contaminant migrating to the product or directly to the skin. However, if the contaminant is impermeable and present on the surface of the plastic, such contaminant has the ability to migrate to the product or to the skin through direct contact migration, making it unacceptable for use in these demanding applications. Both permeable and impermeable surface contaminants can be converted to bulk contaminants through convective mechanisms such as melt mixing and melt densification. These methods replace or reduce the surface area with bulk material. For example, if a surface-contaminated film is melt-densified or melt-extruded into a different shape, such as pellets, all of the original surface contamination, whether impermeable or not, becomes bulk contamination, making such bulk contamination more difficult to remove in a refining process. Melt densification is common in the recycling industry. Shredding incoming plastics is also common in the recycling industry. The latter method generally does not convert surface contamination into bulk contamination. Ideally, a surface refining method, such as surface washing, is performed on the original contaminated surface, such as the shredded film, allowing the surface washing fluid to reach all of the original surface area.

[0130] Generally, it is difficult to distinguish between surface and bulk contamination using analytical methods. Most analytical methods for permeable chemical contaminants involve solvent extraction of contaminants from plastics for extended periods of time (over six hours), exposing them to extreme solvent-to-plastic mass ratios (over 100:1), and then quantifying the contaminants in the solvent using methods such as gas chromatography-mass spectrometry (GC-MS). While such analytical methods quantify contamination, they do not distinguish between surface and bulk contaminants. The efficiency of a purification method for removing surface contaminants can be estimated from the difference in contamination before and after the surface cleaning step, but this assumes that bulk contamination is not significantly affected, as in the case of surface cleaning with aqueous surface cleaning fluids discussed in this invention. A more accurate method for quantifying surface contamination is to wash the contaminants at various time points, then solvent extract them, and then extrapolate the amount of contaminant removed at the minimum time point to approximate the amount of surface contamination. However, this method is time-consuming and expensive, especially for contaminants that are generally difficult to measure. Furthermore, the balance between surface and bulk contaminants is dynamic and therefore difficult to quantify without reference to an accurate sampling time. A simple method to quantify general surface contamination (not chemical surface contamination or species-based chemical contaminants) is to weigh the recycled polymer before and after the surface cleaning step.

[0131] Generally, bulk contamination is not significantly removed by simple aqueous surface cleaning. Permeable bulk contamination can be removed by diffusion mechanisms driven by chemical potential gradients. Bulk impermeable contamination is essentially trapped by the bulk polymer, and methods for removing trapped contaminants include melt convection, melt filtration, and plastic dissolution / decomposition.

[0132] 1. In an embodiment of the present invention, a method for purifying recycled polymers includes: a) obtaining recycled polymers, wherein the recycled polymers are selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof, wherein the recycled polymers include contaminants, each contaminant having a concentration, and wherein the contaminants in the recycled polymer include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates. In an embodiment of the present invention, a method for purifying recycled polymers includes: a) obtaining recycled polymers, wherein the recycled polymers are selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof, wherein the recycled polymers include contaminants, each contaminant having a concentration, and wherein the contaminants in the recycled polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate. In an embodiment of the present invention, the alkylphenols, bisphenols, dioxins, PCBs, and phthalates include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate.

[0133] IV. Surface purification method Surface purification reduces surface contamination. One such method is surface cleaning with a surface cleaning fluid, which is typically aqueous. Ideally, surface cleaning should be completed before melt compounding or melt densification to allow for effective cleaning of the original contaminated surface. Recycled polymers are generally in the form of pellets, loose or compressed film, loose or compressed flexible packaging, loose or compressed rigid objects, loose or compressed nonwoven fabrics, etc., which are difficult to surface clean due to their large overall size. Therefore, a granulation or shredding step is preferred before surface cleaning. In the case of films, it is particularly important to strip all available film layers so that the cleaning fluid can access all original surface contamination. Therefore, the size reduction step before surface cleaning should not significantly reduce the average surface area-to-volume ratio of the recycled resource or replace new surface area.

[0134] In an embodiment of the invention, surface washing of the recycled polymer occurs after the shredding or granulation process. Surface washing involves vigorous mechanical agitation to loosen surface dirt and other contaminants, allowing for physical removal and transfer to a washing fluid in which the dirt or other contaminants may or may not be solubilized.

[0135] As used herein, in a surface cleaning process, recycled plastic, in its original, contaminated form (except where bulk size reduction may result in less than 25% reduction in the original surface), is contacted with an aqueous solution under mechanical agitation and then separated from the aqueous medium containing such contaminants. Such surface cleaning processes generally remove most of the loosely bound surface contaminants, including, but not limited to, dirt, wood, loosely bound paper, and some surface chemical contaminants. Typical levels of loosely bound surface contaminants for film-based recycled materials are about 0.01-0.1% by weight. In embodiments of the present invention, surface cleaning removes greater than about 80% of the loosely bound surface contaminants.

[0136] Surface cleaning technologies are widely available on the market. One technology is from Lindner (Lindner Washtech GmbH, Haldenfeld 4, Germany). This technology, described in detail elsewhere (https: / / www.lindner-washtech.com / system-solutions), involves water washing under intense mechanical agitation, as well as the application of caustic alkali to remove adhesives, followed by drying and possibly pelletizing. Another technology is from Herbold (Herbold Meckesheim USA, North Smithfield, Rhode Island, USA). This technology, described in detail elsewhere (https: / / www.herbold.com / en / machines / washing-separating-drying-2 / ), also includes various water washing steps under intense mechanical agitation, followed by drying and pelletizing. Another technology is from Sorema (Sorema Srl, Anzano del Parco, Italy). This technique, described in detail elsewhere (http: / / sorema.it / en_US / applications / washing-line / ), involves similar aqueous operations compared to Lindner and Herbold. Finally, another technique is from Cadel (Cadel Deinking, Alicante, Spain), called deinking. This technique, described elsewhere (http: / / cadeldeinking.com / en / ), essentially involves cleaning the surface of the material using a hot aqueous solution containing specific surfactants, followed by rinsing with water and drying. This process may optionally include densification after surface cleaning, melt filtering, devolatilization, and pelletization. This method differs from other known methods in that it removes surface-printed ink. This may be advantageous for reducing the burden of chemical contaminant removal by the bulk purification method of the present invention.

[0137] Three prior art surface cleaning technologies were evaluated for average removal efficiency of five selected contaminants (Comparative Examples 1, 2, and 3). Each surface cleaning technology was evaluated using different recycled films with different levels of contamination. Overall, the prior art surface cleaning technologies were unable to purify the recycled polymer sufficiently for use in controlled end markets. Commercially available technologies were unable to reduce the selected contaminants to levels near the LOQ, despite the initial light contamination of each recycled polymer. Additionally, the average removal efficiency of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate was less than approximately 55%.

[0138] In an embodiment of the invention, the recycled 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, the surface washing resulting in a reduction of loosely bound surface contamination by greater than about 80%. In an embodiment of the invention, the recycled 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, the surface washing resulting in a reduction of loosely bound surface contamination by greater than about 80%, the recycled polymer prior to surface washing having a density of less than about 1 mm -1 and the surface cleaning process is a deinking-type surface cleaning process, which results in a ΔE change of less than about 10% between the deinked polymer and the recycled polymer that does not contain the surface-printed ink.

[0139] V. Melt Densification Process The plastics emerging from the surface refining process generally have a similar geometric shape and average surface area to volume ratio to the incoming recycled polymer, assuming the surface refining temperature was below the recycled polymer's primary melting point. For example, if the recycled plastic is a loose film, after shredding and surface washing at a temperature below the recycled polymer's primary melting point, the film will exit surface refining as a shredded film. Because such loose plastics are difficult to feed into certain bulk refining methods, such as liquid-liquid extraction, it may be desirable to melt-densify such plastics prior to bulk refining.

[0140] A preferred method of melt densification is melt extrusion. Melt extrusion not only densifies the plastic but can also provide the pressure necessary for downstream bulk refining, such as liquid-liquid extraction. Melt extrusion may also include optional steps such as melt filtration and / or devolatilization to remove large and / or volatile bulk contaminants. In addition, the melt densified plastic may be further pressurized using a melt pump. A melt pump may be necessary to increase the pressure necessary for downstream bulk refining steps. Other densification methods, including rotating disk densifiers and rotating drum densifiers, which operate at lower temperatures compared to melt-based methods, are known in the art.

[0141] In an embodiment of the invention, melt densification comprises melt extrusion. In an embodiment of the invention, melt extrusion comprises melt filtration. In an embodiment of the invention, melt extrusion comprises melt devolatilization. In an embodiment of the invention, melt extrusion comprises melt pumping. In an embodiment of the invention, melt densification comprises melt extrusion, melt filtration, melt devolatilization, and melt pumping.

[0142] VI. Immersion Leaching Process Unexpectedly, it has been discovered that a combined surface purification and immersion leaching process (disclosed in Section VII) in combination with an immersion leaching process (disclosed in Section VI hereof) or a purification process (disclosed in Section VIII) produces a higher purity polymer from recycled polymer at a much higher efficiency than when the purification process is used alone. While not wishing to be bound by any theory, Applicants hypothesize that the removal of contaminants in the leaching process allows for a higher removal efficiency of residual contaminants in various steps of the purification process compared to the absence of a leaching process or a surface purification and leaching process. While not wishing to be bound by any theory, Applicants believe that surface contaminants in recycled polymers become bulk contaminants in the absence of a leaching process or a surface purification and leaching process, and are therefore difficult to remove in the various steps of the purification process.

[0143] Generally, bulk contamination is not significantly reduced by simple aqueous surface washing. Melt filtration and melt devolatilization remove bulk contaminants of large geometric size and may remove some volatile bulk contaminants, but are often not as effective against most bulk contaminants as is particularly desired.

[0144] One commercially available technology for bulk purification is InterRema Refresher® from EREMA (EREMA Group, Ansfelden, Austria; https: / / www.erema.com / en / refresher / ). This technology has been described in detail elsewhere, but essentially consists of devolatilizing pelletized material at temperatures below the primary melting point of the plastic for an extended period of time to remove volatile organics. Most of the chemical contaminants associated with recycled polymers and discussed in the previous section typically have normal boiling points above 200°C and are highly non-volatile. Therefore, this type of devolatilizing technology has limited ability to remove most of the chemical contaminants mentioned in this application.

[0145] Other technologies based on devolatilization are common. These may be stand-alone unit operations or may be combined with other operations, including extrusion and melt filtration. They commonly utilize subatmospheric pressure on the recycled plastic melt stream. One bulk purification technology with devolatilization was analyzed for its purification capabilities. This technology included a slightly elevated temperature but below the primary melting point of the plastic, a long residence time (greater than about 2 hours), and continuous reflux of purified air to provide devolatilization (Comparative Example 4). Commercially available devolatilization technologies were unable to adequately remove selected contaminants. For example, the selected contaminants were still far above the LOQ, with an average removal efficiency of about 41%.

[0146] Extraction is a preferred bulk purification method. Extraction involves the use of a purification solvent to remove bulk permeable contaminants by creating a chemical potential gradient between the recycled polymer and the solvent. The removal rate of permeable chemical contaminants depends on the diffusivity and solubility of the contaminant in the plastic under the conditions encountered during the process. For high-MW plastics, the diffusivity of large molecules representing chemical contaminants is very low, especially in the solid state of the plastic. Furthermore, solubility can be limited due to the high MW of the recycled polymer and lack of enthalpy mixing. Therefore, the time required to remove permeable contaminants by a diffusion mechanism can be very long and may not be conducive to an economically viable process on a commercial scale. Methods to overcome these timescale limitations include: 1) enhancing diffusivity through elevated temperatures and / or plastic relaxation through solvent swelling; 2) reducing the diffusion path length by increasing the average surface area-to-volume ratio of the recycled polymer exposed to the solvent; and 3) increasing contaminant solubility in the solvent, improving contaminant partitioning in the solvent compared to the plastic, increasing convection around the plastic / solvent interface, and increasing the solvent sink compared to the plastic sink, thereby increasing convective transport of contaminants through the plastic / solvent interface. The solubility of the bulk refinery solvent in the plastic can be improved by operating the extraction at elevated pressures, particularly at, near, or above the critical pressure.

[0147] It is important that the extraction method can be expanded to large volumes at low cost. Therefore, to enable such scalability, the time required for extraction must be short. In an embodiment of the present invention, the total time for extraction is less than about 6 hours, preferably less than about 4 hours, more preferably less than about 2 hours, and even more preferably less than about 1 hour. If the extraction is completed in stages, the time per stage may be less than this range, but the total time will still fall within these times.

[0148] Extraction can occur above, near, at, or below the first melting point of the recycled polymer. Extraction that occurs at, near, or above the first melting point of the recycled polymer is called liquid-liquid extraction. Extraction that occurs below the first melting point of the recycled polymer is called percolation extraction, or simply percolation process. The extraction solvent used in percolation extraction is called the percolation solvent.

[0149] In the immersion leaching process of the present invention, the recycled polymer is contacted with excess solvent at all stages and times of the process. Such a leaching process is referred to as an immersion leaching process. For purposes of this invention, the terms "immersion leaching" and "leaching" are used interchangeably. Also, for purposes of this invention, the terms "process," "step," "process step," and their plurals are used interchangeably.

[0150] In the leaching process, the mass ratio of the leaching solvent to the mass of the recycled polymer exposed to the solvent is preferably at least about 5:1 at all times and stages of the process. In some leaching processes, the solvent is rapidly agitated so that the recycled polymer is suspended in the solvent, even if the density of the recycled polymer is greater than that of the solvent. Such a leaching process ensures complete contact between the surface of the recycled polymer and the leaching solvent, reducing mass transfer resistance within the solvent boundary layer around the recycled polymer surface due to convective motion. In addition to agitation, a similar reduced boundary layer can be achieved in an immersion leaching process by precipitating the recycled polymer through the solvent via a density gradient. Examples of immersion leaching processes include continuous-type stirred tanks (also known as continuous stirred tank reactors - CSTRs), semi-continuous-type stirred tanks, and batch-type stirred tanks. Further examples of immersion leaching processes include precipitation tanks, which allow the recycled polymer to precipitate through a solvent filled inside a tank or other vessel. Applicants have found that for the immersion leaching process of the present invention, the weight ratio of leaching solvent to recycled polymer at any time and in any stage should preferably be greater than about 5:1, more preferably greater than 10:1 per stage, and most preferably greater than about 20:1, to allow for adequate dispersion and exfoliation of the recycled polymer in the leaching solvent.

[0151] In an embodiment of the invention, the immersion leaching step is carried out in a stirred tank. In an embodiment of the invention, the immersion leaching step is carried out in a CSTR. In an embodiment of the 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 important. The reactor design should include the possibility of vigorous mechanical agitation and prolonged baffling.

[0152] In the immersion leaching process of the present invention, it may be beneficial to select the leaching solvent and the operating temperature and pressure so that the leaching solvent is at its boiling point during extraction. Such a design allows for continuous reflux of the solvent, which can create a locally high concentration gradient as the refluxed solvent contacts the regenerated polymer.

[0153] In an embodiment of the present invention, the immersion leaching step is carried out at a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric pressure to about 1,000 atm. In an embodiment of the present invention, the immersion leaching step is carried out at a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric pressure to about 1,000 atm. In an embodiment of the present invention, the immersion leaching step is carried out in multiple leaching stages using a leaching solvent at a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric pressure to about 1,000 atm, for the total residence time of the immersion leaching step and the residence time of each leaching stage.

[0154] In an embodiment of the present invention, the leaching solvent has a normal boiling point or thereabouts. For recycled polyolefin polymers, preferred leaching solvents for immersion leaching 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 an embodiment of the present invention, the leaching solvent has a normal boiling point of 20°C to 90°C. In an embodiment of the present invention, the leaching solvent has a normal boiling point of 20°C to 90°C, and the leaching temperature is at or near the boiling point. In an embodiment of the present invention, the leaching solvent has a normal boiling point of 20°C to 90°C, and the leaching temperature is at or near the boiling point, and the leaching pressure is near atmospheric pressure. For such leaching solvents, the pressure may be higher than atmospheric pressure. In an embodiment of the present invention, the leaching solvent has a normal boiling point of 20°C to 90°C, and the leaching pressure is above atmospheric pressure to about 1,000 atm. The leaching solvent may have a boiling point higher than the leaching temperature. In an embodiment of the present invention, the leaching solvent has a normal boiling point higher than the leaching temperature. In an embodiment of the present invention, the leaching solvent is ethyl acetate, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is near atmospheric pressure to about 1,000 atm. In an embodiment of the present invention, the leaching temperature is about 20°C to about 90°C, the leaching pressure is near atmospheric pressure to about 1,000 atm, the leaching solvent is ethyl acetate, the total residence time of the leaching step is less than about 360 minutes, and the average removal efficiency is about 55%. In an embodiment of the present invention, the leaching solvent is hexane, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is near atmospheric pressure to about 1,000 atm.

[0155] Leaching solvents having a normal boiling point below the leaching temperature are also preferred because they have a high immersion leaching pressure. In an embodiment of the present invention, the leaching solvent has a normal boiling point below the leaching temperature. In an embodiment of the present invention, the leaching solvent is propane. In an embodiment of the present invention, the leaching solvent is propane, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is about 9 atm to about 1,000 atm. In an embodiment of the present invention, the leaching solvent is dimethyl ether (DME). In an embodiment of the present invention, the leaching solvent is DME, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is about 6 atm to about 1,000 atm.

[0156] Leaching solvents having a normal boiling point below the leaching temperature and a critical temperature below the leaching temperature are also preferred. In an embodiment of the present invention, the leaching solvent has a normal boiling point below the leaching temperature and its critical temperature is below the leaching temperature. In an embodiment of the present invention, the leaching solvent is ethane. In an embodiment of the present invention, the leaching solvent is critical ethane or supercritical ethane. In an embodiment of the present invention, the leaching solvent is ethane, the leaching temperature is about 31°C to about 120°C, and the leaching pressure is about 40 atm to about 1,000 atm. In an embodiment of the present invention, the leaching solvent is CO2. In an embodiment of the present invention, the leaching solvent is CO2, the leaching temperature is about 31°C to about 120°C, and the leaching pressure is about 68 atm to about 1,000 atm. In an embodiment of the present invention, the leaching solvent is CO2 containing less than 5% water by weight.

[0157] The density of the leaching solvent is preferably less than the density of the recycled polymer at the temperatures and pressures of the immersion leaching process. For recycled polyethylene, the density of the leaching solvent at the temperatures and pressures of the immersion leaching process is preferably less than about 0.90 g / mL, although higher densities may be used.

[0158] Preferred leaching solvents include those that have a higher affinity for chemical contaminants than the recycled polymer. Solvents that have a higher affinity for the target chemical contaminants in the recycled polyolefins compared to their affinity for these polyolefins include, but are not limited to, diethyl ether, MEK, ethyl acetate, THF, acetone, methylene chloride, and methanol. Other oxygenated polar hydrocarbon solvents likely have similar desired affinities. Solvents lacking such properties can also be used, but may require a higher solvent-to-polymer ratio. Preferably, the solvent does not significantly dissolve the recycled polymer (less than about 5% by weight can be dissolved) under the temperatures and pressures of the immersion leaching process.

[0159] In an embodiment of the present invention, the leaching solvent is an organic solvent or a mixture of organic solvents. In an embodiment of the present invention, the leaching solvent is selected from the group comprising hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group comprising aliphatic hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group comprising aromatic hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group comprising alkanes. In an embodiment of the present invention, the leaching solvent is selected from the group comprising methane, ethane, propane, normal butane, isobutane, normal pentane, isopentane, neopentane, hexane (normal hexane, isohexane, neohexane), heptane, octane, or a mixture thereof. In an embodiment of the present invention, the leaching solvent is at least one of DME, diethyl ether, MEK, ethyl acetate, THF, acetone, methanol, and CO2, or a mixture thereof.

[0160] The temperature may be varied during the immersion leaching process but is generally constant within a given stage of the unit operation. The pressure may be varied to change the solubility of the leaching solvent in the recycled polymer or to improve the solubility of chemical contaminants in the leaching solvent.

[0161] The immersion-percolation extraction process may be performed in stages or may be combined with other types of additional percolation steps not discussed in this disclosure. The same is true for liquid-liquid extraction processes. In addition, liquid-liquid extraction processes may be combined with immersion-percolation steps at various stages to form a given purification process. In embodiments of the present invention, the number of percolation steps is two or more. In embodiments of the present invention, the number of percolation steps is from about 1 to about 50. In embodiments of the present invention, the number of percolation steps is from about 2 to about 30. In embodiments of the present invention, the number of percolation steps is from about 5 to about 20. In embodiments of the present invention, the number of liquid-liquid steps is two or more. In embodiments of the present invention, the number of percolation steps is two or more. In embodiments of the present invention, the number of liquid-liquid steps is one or more and the number of percolation steps is one or more.

[0162] A single stirred-tank reactor achieves a certain removal efficiency. Efficiency can be improved by having multiple stirred-tank reactors in series, where the recycled polymer from the first stage is primarily separated from the first-stage leach solvent, and this first-stage plastic is used in the second stage along with fresh leach solvent. This is repeated for each additional stage. This method improves removal efficiency at the expense of additional reactors and complexity, while maintaining overall time, throughput, and solvent utilization. In practice, the number of reactor stages can be anywhere from one to about ten for a stirred-tank system. If more stages are required, a continuous countercurrent process can be used.

[0163] Without wishing to be bound by theory, the theoretical maximum contaminant removal capacity of the immersion leaching process is based on the thermodynamic equilibrium / partitioning of chemical contaminants between the recycled polymer and the leaching solvent at the temperature and pressure of the immersion leaching process. Thermodynamic equilibrium may not be achieved due to kinetic limitations in the immersion leaching process. This applies to the overall immersion leaching process and to each immersion leaching stage. A higher leaching solvent-to-recycled polymer mass ratio makes leaching thermodynamically and kinetically favorable, at the expense of greater leaching solvent consumption and a larger leaching process size, which correspond to greater costs. Therefore, a balance must be found between these key design and operating variables for the removal efficiency of a selected chemical contaminant.

[0164] In general, applicants have found that the total mass ratio of fresh or recycled leaching solvent to recycled polymer is preferably greater than about 5:1. In embodiments of the invention, the total mass ratio of fresh or recycled leaching solvent to recycled polymer is greater than about 10:1. In embodiments of the invention, the total mass ratio of fresh or recycled leaching solvent to recycled polymer is greater than about 15:1. In embodiments of the invention, the total mass ratio of fresh or recycled leaching solvent to recycled polymer is greater than about 20:1. In embodiments of the invention, the total mass ratio of fresh or recycled leaching solvent to recycled polymer is greater than about 30:1 and less than about 100:1.

[0165] If immersion leaching is completed in stages or in succession, the leaching solvent to regenerated polymer ratio per stage may be lower than this stated range (but still exceed the minimum per stage of about 5:1), but the total solvent used relative to the total regenerated polymer, represented by the sum of the solvents used in all stages, should be within this range. Furthermore, contaminated solvent from any stage can be used "as is" as the solvent for another stage. Contaminated solvent at any point in the process can be regenerated by known methods, such as distillation, filtration, ion exchange, or a combination thereof.

[0166] Another important kinetic contributor is the average surface area-to-volume ratio of the recycled polymer in and exposed to the leaching solvent. In general, the time required to extract chemical contaminants from the recycled polymer is strongly related to the diffusion path length within the recycled polymer. The diffusion path length is indirectly proportional to the average surface area-to-volume ratio of the recycled polymer's geometry and the ability of the leaching solvent to access the surface area. Therefore, a higher average surface area-to-volume ratio results in a shorter diffusion path length and faster diffusion kinetics. In the immersion leaching process, a high average surface area-to-volume ratio is a key parameter for rapid and efficient contaminant removal, both surface and bulk.

[0167] In the immersion leaching process, because the processing temperature is below the primary melting point, the average surface area to volume ratio of the recycled polymer in and exposed to the extraction solvent is essentially the same as the average surface area to volume ratio of the recycled polymer. The immersion leaching process is ideal for film-based recycled polymers, as they inherently have a very high average surface area to volume ratio. When recycled polymers are provided in other forms with lower average surface area to volume ratios, such as pellets, granulated bottles, or granulated parts, it may 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.

[0168] A known means for increasing the effective mass transfer for a given surface area to volume ratio and a given set of conditions at the interface between the recycled polymer and the leaching solvent is by applying energy to the recycled polymer, such as, but not limited to, ultrasonic energy and / or vibrations in the form of microwaves.

[0169] Following the immersion leaching process, the leached polymer can be devolatilized to remove the leaching solvent. The contaminated leaching solvent contains small amounts of dissolved recycled polymer, leached contaminants, and pure leaching solvent. There are many methods to recover higher purity polymer and leaching solvent, independent of the leached contaminants.

[0170] Generally, regardless of the process type or leaching solvent, a small amount of recycled polymer may dissolve in the leaching solvent. Low MW waxes, in particular, tend to solubilize in the leaching solvent. This can be problematic in distillation-based recovery of purified leaching solvent due to wax deposition on process equipment. Methods are known to reduce this tendency. One such method is to reduce the temperature of the contaminated leaching solvent below its cloud point to precipitate the polymer or wax phase, followed by filtration. Unlike recycled polymer, the residual plastic or wax resulting from precipitation from the contaminated solvent can contain significant contamination.

[0171] Distillation of contaminated leaching solvent can be used to regenerate the leaching solvent for reuse in various leaching operations. However, distillation may not be economically viable on an ongoing basis given the high leaching solvent volumes utilized in this invention. Furthermore, because the chemical contaminants targeted by this invention are present in extremely low concentrations, the concentrations of these chemical contaminants in the contaminated leaching solvent may be correspondingly low, or even lower. Therefore, a preferred method of purifying the contaminated leaching solvent is by directly removing the contaminants without volatilizing the bulk leaching solvent phase. Such methods include ion exchange, adsorption / absorption techniques, and the like, such as passing the contaminated leaching solvent through a bed of activated carbon, alumina, or activated alumina. This method can be used alone or in combination with distillation to achieve an appropriate level of purification with reasonable energy consumption. Furthermore, 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 regenerated by known methods, such as distillation, filtration, ion exchange, or a combination thereof.

[0172] The leached polymer may contain small amounts of leaching solvent, either physically adsorbed or bulk absorbed. The concentration of leaching solvent in the leached polymer may be reduced by devolatilization techniques. In an embodiment of the present invention, the leached polymer is devolatilized until the leaching solvent content in the leached polymer is less than 1 wt. %.

[0173] Stirred tank reactors operating at the boiling point of the leaching solvent offer improvements over existing methods. For example (Examples 1, 2, 3, and 4; and Tables 7, 8, 9, and 10), immersion leaching processes conducted with ethyl acetate or THF provide removal efficiencies of selected contaminants of greater than about 88%.

[0174] In an embodiment of the invention, the leaching solvent is ethyl acetate. In an embodiment of the invention, the leaching solvent is ethyl acetate and the leaching pressure is near atmospheric pressure. In an embodiment of the invention (Example 1 and Table 7), the immersion leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, and the leaching solvent includes ethyl acetate. In an embodiment of the invention, the immersion leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent includes ethyl acetate, and the recycled polymer is leached at a temperature of about 80 mmHg. -1 the number of leaching stages is 2, the ethyl acetate to recycled polymer mass ratio per stage is about 18:1, the immersion leaching residence time per stage is about 50 minutes, the total ethyl acetate to recycled polymer mass ratio is about 36:1, the total residence time is about 100 minutes, and the average concentration reduction of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate is about 89%.

[0175] In an embodiment of the present invention (Example 2 and Table 8), the immersion leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent includes ethyl acetate, and the recycled polymer is about 80 mm -1the number of leaching stages is 2, the ethyl acetate to recycled polymer mass ratio per stage is about 18:1, the immersion leaching residence time per stage is about 30 minutes, the total ethyl acetate to recycled polymer mass ratio is about 36:1, the total residence time is about 60 minutes, and the average concentration reduction of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate is about 89%.

[0176] In an embodiment of the present invention, the leaching solvent is THF. In an embodiment of the present invention, the leaching solvent is THF and the leaching pressure is near atmospheric pressure. In an embodiment of the present invention, the immersion leaching is carried out in a stirred tank, the leaching temperature is about 66°C, the leaching pressure is near atmospheric pressure, and the leaching solvent includes THF. In an embodiment of the present invention (Example 3 and Table 9), the immersion leaching process is carried out in a stirred tank, the number of leaching stages is 2, the leaching temperature is about 66°C, the leaching pressure is near atmospheric pressure, the leaching solvent includes THF, and the recycled polymer is about 80 mmHg. -1 with a surface area to volume ratio of about 18:1 THF to recycled polymer per stage, a residence time for each leaching stage of about 50 minutes, a total THF to recycled polymer mass ratio of about 36:1, a total residence time for the immersion leaching process of about 100 minutes, and an average reduction in concentrations of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate of about 90%.

[0177] In an embodiment 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 an embodiment of the invention, the leaching solvent is DME, and the recycled polymer is about 80 mm -1 In an embodiment of the invention, the leaching solvent is CO2, the leaching temperature is about 70°C, the leaching pressure is about 340 atm, and the recycled polymer has a surface area to volume ratio of about 80 mm -1 has a surface area to volume ratio of

[0178] Following the immersion leaching process, the leached polymer may be physically wetted with residual leaching solvent and may contain small amounts of absorbed leaching solvent. As discussed above, there are many ways to recover the leached polymer and leaching solvent, regardless of the leached contaminants. The leached polymer can be dried and devolatilized by many known, commercially available means. One method is by cyclone drying. Another method is by melt extrusion with a devolatilization step. In an embodiment of the present invention, the leached polymer is treated to reduce the leaching solvent in the reclaimed polymer to less than about 1% by weight. The contaminated leaching solvent can be washed using known methods such as distillation, ion exchange, and filtration. The resulting devolatilized polymer may be used as is or further processed into other forms, including pellets, via various processes.

[0179] In an embodiment of the present invention, the total residence time for the leaching step is less than about 600 minutes. In an embodiment of the present invention, the total residence time for the leaching step is less than about 480 minutes. In an embodiment of the present invention, the total residence time for the leaching step is less than about 360 minutes. In an embodiment of the present invention, the total residence time for the leaching step is less than about 180 minutes. In an embodiment of the present invention, the total residence time for the leaching step is less than about 60 minutes.

[0180] In an embodiment of the present invention, the residence time for each leaching step is less than about 180 minutes. In an embodiment of the present invention, the residence time for each leaching step is less than about 90 minutes. In an embodiment of the present invention, the residence time for each leaching step is less than about 60 minutes. In an embodiment of the present invention, the residence time for each leaching step is less than about 30 minutes. In an embodiment of the present invention, the residence time for each leaching step is about 20 minutes.

[0181] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof; the recycled polymer containing contaminants, each contaminant having a concentration; the recycled polymer contaminants including at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; and b) leaching the alkylphenols, bisphenols, dioxins, PCBs, or phthalates from the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm, for a total residence time and for each residence time of each leaching stage, to produce a leached polymer each containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates having a concentration, the average removal efficiency being greater than about 55%.

[0182] In an embodiment of the invention, the leaching step is carried out in a continuous stirred tank reactor (CSTR), and the recycled polymer is surface washed in a non-densified state in a surface washing process prior to extraction, the surface washing process resulting in a reduction of loosely bound surface contamination by greater than about 80%, and the recycled polymer prior to surface washing has a surface contamination of about 1 mm. -1 the surface cleaning process is a deinking-type surface cleaning process, the deinking process results in a ΔE change of less than about 10% between the deinked polymer and the recycled polymer that does not contain the surface-printed ink, the leaching solvent is ethyl acetate, the CSTR includes three leaching stages, the leaching temperature is about 77°C, the leaching pressure is near atmospheric pressure, the residence time in each leaching stage is about 20 minutes, and the recycled polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets, and the average removal efficiency is greater than about 55%.

[0183] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining recycled polymer, the recycled polymer selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer including contaminants, each contaminant having a concentration, the recycled polymer contaminants including at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate; and b) removing 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate from the recycled polymer. leaching the bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for the residence time of each leaching stage to produce a leached polymer each having a concentration of at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, wherein the average removal efficiency is greater than about 55%.

[0184] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer comprising contaminants, each contaminant having a concentration, the contaminants of the recycled polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) purifying the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs) from the recycled polymer. and leaching the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for each residence time of the leaching stages to produce a leached polymer each containing a concentration of at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, wherein the average removal efficiency of the leached polymer is greater than about 55%.

[0185] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer comprising contaminants, each contaminant having a concentration, the contaminants of the recycled polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) purifying the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs) from the recycled polymer. and leaching the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for each residence time of the leaching stages to produce a leached polymer each containing a concentration of at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, wherein the average removal efficiency of the leached polymer is greater than about 70%.

[0186] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer comprising contaminants, each contaminant having a concentration, the contaminants of the recycled polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) purifying the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs) from the recycled polymer. and leaching the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for each residence time of the leaching stages to produce a leached polymer each containing a concentration of at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, wherein the average removal efficiency of the leached polymer is greater than about 80%.

[0187] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer comprising contaminants, each contaminant having a concentration, the contaminants of the recycled polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) purifying the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs) from the recycled polymer. and leaching the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for each residence time of the leaching stages to produce a leached polymer each containing a concentration of at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, wherein the average removal efficiency of the leached polymer is greater than about 90%.

[0188] VII. Combining Surface Refining with Immersion Leaching Processes Generally, the combination of the surface purification process and the immersion leaching process provides synergistic benefits to the overall removal of contamination. The surface purification process effectively removes both impermeable and permeable surface contamination, including chemical contaminants and chemical contaminant precursors. Therefore, surface purification reduces the burden on the immersion leaching process and makes it more effective. If the recycled polymer is heavily contaminated with surface contamination, such contamination is preferably removed first in the surface purification process, followed by the immersion leaching process. After the surface contamination is removed in the surface purification process, the remaining bulk permeable contamination is removed in the immersion leaching process. The only contamination not significantly removed by this two-step approach is bulk impermeable contamination, such as heavy metals intentionally added during the original plastic part manufacturing process.

[0189] A preferred method of surface cleaning has already been discussed in the Surface Refining section. An even more preferred method of surface cleaning is the deinking method, which is also described in the Surface Refining Method (Comparative Example 3). This method not only removes surface contaminants such as mud, but also surface-printed inks. This method is also very effective for removing paper labels, which are precursors to chemical contaminants. In this method, recycled polymer with its original surface area exposed is fed to a multi-step aqueous cleaning process in which surface contaminants, including surface-printed inks, mud, grit, paper, adhesives, etc., are removed. The resulting material is then dried. The dried material may be further densified into pellets using extrusion, including devolatilization and melt filtration. For purposes of this invention, a deinking method is any surface cleaning method that removes enough surface printing to result in less than about a 10% difference in ΔE (ΔE measured using Method 3 in Section IX) between the deinked recycled polymer and the unprinted recycled polymer.

[0190] For purposes of nomenclature, the surface-purified polymer obtained by feeding recycled polymer to the surface purification process is referred to as a surface-washed polymer. The surface-washed polymer is then fed to an immersion leaching process, and the resulting polymer is referred to as a leached polymer. The surface purification process may include multiple surface purification processes. The immersion leaching process may include multiple immersion leaching processes of various types. The removal efficiency of the combined surface purification and immersion leaching processes is calculated from the recycled polymer concentration and the associated leached polymer. The combined surface washing and immersion leaching process resulted in an average concentration reduction of approximately 95% for bisphenol A, 4-tert-pentylphenol, OCDD, PCB108, and di-2-ethylhexyl phthalate (Example 4 and Table 10).

[0191] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of a PCR polymer, a PIR polymer, and combinations thereof; the recycled polymer containing contaminants, each contaminant having a concentration, the contaminants of the recycled polymer including at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) surface-washing the recycled polymer to produce a surface-washed polymer; and c) leaching the alkylphenols, bisphenols, dioxins, PCBs, and phthalates from the surface-washed polymer at an average removal efficiency using a leaching solvent at a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm, for a total residence time and for each residence time of each leaching stage, to produce a leached polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates, each having a concentration, the average concentration reduction being greater than about 55%.

[0192] In an embodiment of the present invention, the immersion leaching step is performed after the surface cleaning. In an embodiment of the present invention, the immersion leaching step is performed after the surface cleaning process, and the recycled polymer is not densified before the surface cleaning process. In an embodiment of the present invention, the immersion leaching is performed after the surface cleaning process, and the recycled polymer is not densified before the surface cleaning process, and the surface-washed recycled polymer may be densified before the immersion leaching step.

[0193] In an embodiment of the invention, the immersion leaching process uses a leaching solvent under a temperature and pressure, the immersion leaching process is carried out in multiple stages, and the reclaimed polymer is partially purified using a surface washing process.

[0194] In an embodiment of the invention (Example 4 and Table 10), the surface cleaning process comprises commercial deinking with Cadel, which results in less than about 10% ΔE change and greater than about 80% removal of loosely bound surface contaminants, the immersion leaching step is carried out in an agitated tank, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent includes ethyl acetate, and the total residence time is about 60 minutes. In an embodiment of the invention, the surface cleaning process comprises commercial deinking with Cadel, which results in less than about 10% ΔE change and greater than about 80% removal of loosely bound surface contaminants, the immersion leaching step is carried out in an agitated tank over two stages, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent includes ethyl acetate, the residence time per stage is about 30 minutes, and the concentration reduction of OCDD is about 98%.

[0195] In an embodiment of the invention, the surface cleaning process includes any known surface cleaning method, wherein the immersion leaching process uses an agitated tank and the immersion leaching process uses a leaching solvent. In an embodiment of the invention, the immersion leaching process uses an agitated tank and includes multiple leaching stages.

[0196] In an embodiment of the invention, the recycled 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, the surface washing resulting in a reduction of loosely bound surface contamination by greater than about 80%, and the recycled polymer prior to surface washing has a surface contamination of less than about 1 mm. -1 the surface cleaning process is a deinking-type surface cleaning process, the deinking process results in a ΔE change of less than about 10% between the deinked polymer and the recycled polymer that does not contain the surface-printed ink; the leaching step is carried out in a continuous stirred tank reactor (CSTR), the leaching solvent is ethyl acetate, the CSTR includes three leaching stages, the leaching temperature is about 77°C, the leaching pressure is near atmospheric pressure, the residence time in each of the leaching stages is about 20 minutes, the average removal efficiency is greater than about 55%; and the leached polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets.

[0197] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, wherein the recycled polymer includes contaminants, each contaminant having a concentration, and the contaminants of the recycled polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate; and b) surface-washing the recycled polymer in a non-densified state to produce a surface-washed polymer, wherein the surface-washing results in a reduction of more than about 80% of loosely bound surface contaminants. and c) leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for each residence time of each leaching stage to produce a leached polymer each having a concentration of at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate, wherein the average removal efficiency is greater than about 55%.

[0198] In an embodiment of the invention, a method for purifying recycled polymer includes: a) obtaining recycled polyethylene, wherein the recycled polyethylene is post-consumer recycled (PCR) polyethylene, the recycled polyethylene including contaminants, each contaminant having a concentration, the contaminants of the recycled polymer including at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) surface-washing the recycled polymer in a non-densified state to produce a surface-washed polymer, wherein the surface-washing results in a reduction of loosely bound surface contaminants by greater than about 80%. and c) leaching pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs from the reclaimed polymer at an average removal efficiency using ethyl acetate at a temperature of about 55°C to about 65°C and at near atmospheric pressure for a total residence time to produce a leached polymer containing at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, each having a concentration, wherein the average removal efficiency of the leached polymer is greater than about 90%.

[0199] VIII. Dissolution Recycling Process - Purification of Leached Polymer It has surprisingly been discovered that the leached polymer in a high-MW polymer solution can be purified by filtration. This process, illustrated in Figures 1A and 1B, includes: 1) extracting the leached polymer with a fluid solvent at an extraction temperature and extraction pressure to produce an extracted polymer (step c in Figure 1A and step d in Figure 1B); 2) dissolving the extracted polymer in a fluid solvent at a dissolution temperature and dissolution pressure to produce a solution of extracted polymer (step d in Figure 1A and step e in Figure 1B); 3) precipitating the extracted polymer solution at a dissolution temperature and dissolution pressure to produce a solution of precipitated polymer (step e in Figure 1A and step f in Figure 1B); 4) filtering the precipitated polymer solution at a dissolution temperature and dissolution pressure to produce a solution of filtered polymer (step f in Figure 1A and step g in Figure 1B); and 5) separating the filtered polymer from the fluid solvent to produce a higher purity polymer (step g in Figure 1A and step h in Figure 1B). It should be noted that the temperature and pressure values ​​mentioned above may vary for each step. A schematic diagram of the experimental setup used for the extraction step is shown in Figure 3A, and a schematic diagram of the experimental setup used for the dissolution, precipitation, filtration, and separation steps is shown in Figure 3B.

[0200] The dissolution recycling process involves various sequences of extraction, dissolution, precipitation, filtration, and separation steps. In embodiments of the present invention, higher purity polymer can be sourced from the PCR stream and is essentially contaminant-free, pigment-free, odorless, homogeneous, and similar in properties to unrecycled polymer.

[0201] Fluid Solvent In an embodiment of the invention, the fluid solvent has a normal boiling point of less than about 70° C. In an embodiment of the invention, the fluid solvent has a normal boiling point of less than about 70° C. and greater than about −45° C. In yet another embodiment, the fluid solvent has a normal 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 maintains solvents with normal boiling points below the operating temperature range of the invention in a state where they produce little or no solvent vapor.

[0202] In an embodiment of the present invention, the fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof. In an embodiment of the present invention, the aliphatic hydrocarbon of the fluid solvent is selected from the group consisting of C1-C6 aliphatic hydrocarbons and mixtures thereof. In an embodiment of the present invention, the fluid solvent comprises n-butane, butane isomers, or mixtures thereof.

[0203] In an embodiment of the present invention, the fluid solvent having a normal boiling point of less than about 70° C. is selected from the group consisting of carbon dioxide, ketones, alcohols, ethers, esters, alkenes, alkanes, and mixtures thereof. Non-limiting examples of fluid solvents having a normal 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, isomers of isohexane, and others that may be apparent to one skilled in the art.

[0204] The selection of an appropriate fluid solvent or solvent mixture will depend on the polymer or polymer mixture to be purified by the present invention. Furthermore, the selection of the polymer to be purified and the corresponding fluid solvent used will dictate the temperature and pressure ranges used to carry out the process of the present invention. A review of polymer phase behavior in fluid solvents of the type described in this invention is provided in the following reference: McHugh et al. (1999) Chem. Rev. 99:565-602.

[0205] extraction In an embodiment of the present invention, a method for purifying a leached polymer includes contacting the leached polymer with a fluid solvent under a temperature and pressure at which the leached polymer is essentially insoluble in the fluid solvent. Without being bound by theory, applicants believe that the temperature- and pressure-dependent solubility can be controlled in a manner that prevents the fluid solvent from completely solubilizing the leached polymer. However, the fluid solvent can diffuse into the leached polymer and extract any extractable contaminants. These extractable contaminants may be residual processing aids added to the polymer, residual product formulations that have contacted the polymer (e.g., perfumes and flavorings, dyes, and other extractable materials that have been intentionally added or unintentionally incorporated into the polymer (e.g., during waste collection and subsequent accumulation with other waste materials).

[0206] In an embodiment of the present invention, controlled extraction can be achieved by fixing the temperature of the polymer / fluid solvent system and then controlling the pressure to a pressure or pressure range below where the polymer dissolves in the fluid solvent. In an embodiment of the present invention, controlled extraction can be achieved by fixing the pressure of the polymer / solvent system and then controlling the temperature to a temperature or temperature range below where the polymer dissolves in the fluid solvent. Extraction of the leached polymer with a fluid solvent under controlled temperature and pressure involves the use of a suitable pressure vessel, which can be configured to allow for continuous extraction of the leached polymer with the fluid solvent. In an embodiment of the present invention, the pressure vessel can be a continuous liquid-liquid extraction column in which molten polymer is pumped into one end of the extraction column and fluid solvent is pumped into the same or opposite end of the extraction column. In an embodiment of the present invention, the fluid containing the extracted impurities is removed from the process. In an embodiment of the present invention, 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 an embodiment of the present invention, extraction may be carried out as a batch procedure in which the leached polymer is immobilized in a pressure vessel and the fluid solvent is continuously pumped through the immobilized polymer phase. The extraction time or amount of fluid solvent used depends on the desired purity of the final higher purity polymer and the amount of extractable contaminants in the starting leached polymer. In an embodiment of the present invention, the fluid containing the extracted contaminants is contacted with a solid medium in a separate step as described below. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polymer with a fluid solvent at a temperature and pressure at which the leached polymer is molten and in a liquid state. In an embodiment of the present invention, the leached polymer is contacted with a fluid solvent at a temperature and pressure at which the leached polymer is in a solid state.

[0207] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polymer with a fluid solvent at a temperature and pressure at which the polyethylene remains essentially undissolved. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polymer with a fluid solvent at a temperature and pressure at which the leached polymer remains essentially undissolved. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polymer with a fluid solvent at a temperature of from about 80°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polymer with a fluid solvent at a temperature of from about 110°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached 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 an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached 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 an embodiment of the invention, the pressure in the extraction step is less than about 1,100 psig (7.58 MPa).

[0208] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a temperature of from about 80°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a temperature of from about 100°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a temperature of from about 130°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a pressure of from about 400 psig (2.76 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a pressure of from about 800 psig (5.52 MPa) to about 5,000 psig (34.47 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 4,500 psig (31.03 MPa).

[0209] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a temperature of from about 80°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a temperature of from about 100°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a temperature of from about 130°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a pressure of from about 400 psig (2.78 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a pressure of from about 800 psig (5.52 MPa) to about 2,800 psig (19.31 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a pressure of from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0210] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a temperature of from about 80°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a temperature of from about 100°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a temperature of from about 130°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a pressure of from about 150 psig (1.03 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 2,750 psig (18.96 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a pressure of from about 1,500 psig (10.34 MPa) to about 2,500 psig (17.24 MPa).

[0211] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a temperature of from about 80°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a temperature of from about 100°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a temperature of from about 130°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a pressure of from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a pressure of from about 1,000 psig (6.89 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a pressure of from about 2,000 psig (13.79 MPa) to about 4,000 psig (27.58 MPa).

[0212] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with a fluid solvent at a temperature and pressure at which the polystyrene remains essentially undissolved. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a temperature of from about 90°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a temperature of from about 100°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a temperature of from about 120°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a pressure of from about 500 psig (3.45 MPa) to about 5,000 psig (34.47 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0213] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached poly(dimethylsiloxane) with a fluid solvent at a temperature and pressure at which the poly(dimethylsiloxane) remains essentially undissolved. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached poly(dimethylsiloxane) with n-butane at a temperature of from about 100°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached poly(dimethylsiloxane) with n-butane at a temperature of from about 115°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached poly(dimethylsiloxane) with n-butane at a temperature of from about 120°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached 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 an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached 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 an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached poly(dimethylsiloxane) with n-butane at a pressure of from about 500 psig (3.45 MPa) to about 1,000 psig (6.89 MPa).

[0214] In an embodiment of the invention, a method for purifying reclaimed polymer includes contacting the leached polymer with a first fluid solvent having a normal boiling point 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 an extracted polymer.

[0215] Dissolution In an embodiment of the present invention, a method for purifying recycled polymers includes dissolving an extracted polymer in a fluid solvent at a temperature and pressure at which the polymer dissolves in the fluid solvent. Without being bound by theory, applicants believe that the temperature and pressure can be controlled in a manner that achieves thermodynamically favorable dissolution of the recycled polymer in the fluid solvent. Furthermore, the temperature and pressure can be controlled in a manner that allows dissolution of a particular polymer or polymer mixture while not dissolving other polymers or polymer mixtures. This controllable dissolution allows for separation of the polymer from the polymer mixture.

[0216] In an embodiment of the present invention, a method for purifying an extracted polymer involves dissolving the extracted polymer in a fluid solvent that does not dissolve contaminants under the same temperature and pressure conditions. These contaminants may include pigments, fillers, dirt, and other polymers. These contaminants are released from the extracted polymer upon dissolution and then removed from the polymer solution by a subsequent solid-liquid separation step.

[0217] In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in a fluid solvent at a temperature and pressure such that the polyethylene dissolves in the fluid solvent. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a temperature of from about 90°C to about 280°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a temperature of from about 110°C to about 220°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted 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 an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a pressure of from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0218] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted polyethylene in n-butane at a pressure of from about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0219] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-butane at a weight percent concentration of up to 20%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 12%.

[0220] In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in propane at a temperature of about 90°C to about 280°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in propane at a temperature of about 100°C to about 220°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in propane at a temperature of about 130°C to about 180°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-pentane at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-pentane at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted polyethylene in n-pentane at a pressure of from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0221] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-pentane at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polyethylene in n-pentane at a weight percent concentration of up to 20%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a weight percent concentration of up to 12%.

[0222] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polypropylene in a fluid solvent at a temperature and pressure such that the polypropylene dissolves in the fluid solvent. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polypropylene in n-butane at a temperature of from about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polypropylene in n-butane at a temperature of from about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polypropylene in n-butane at a temperature of from about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polypropylene in n-butane at a pressure of from about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted 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 an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted polypropylene in n-butane at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

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

[0224] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polypropylene in propane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polypropylene in propane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polypropylene in propane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polypropylene in propane at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving extracted polypropylene in propane at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted polypropylene in propane at a pressure of from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

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

[0226] In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in a fluid solvent at a temperature and pressure such that the extracted polystyrene dissolves in the fluid solvent. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a temperature of from about 90°C to about 280°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a temperature of from about 100°C to about 220°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a temperature of from about 130°C to about 180°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted 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 an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted 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 an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a pressure of from about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

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

[0228] In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in a fluid solvent at a temperature and pressure such that the extracted poly(dimethylsiloxane) dissolves in the fluid solvent. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a temperature of about 115°C to about 280°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a temperature of about 120°C to about 220°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a temperature of about 140°C to about 180°C. In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0229] In an embodiment of the present invention, a method for purifying extracted poly(dimethylsiloxane) comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying extracted poly(dimethylsiloxane) comprises dissolving the extracted poly(dimethylsiloxane) in n-butane at a weight percent concentration of up to 20%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 12%.

[0230] In an embodiment of the present invention, a method for purifying reclaimed polymer includes dissolving the extracted 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.

[0231] In an embodiment of the present invention, the extracted polymer is dissolved in a fluid solvent or a mixture of fluid solvents at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the temperature during the dissolving step is from about 110° C. to about 220° C. In an embodiment of the present invention, the pressure during the dissolving step is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0232] precipitation In an embodiment of the present invention, a method for purifying a polymer includes separating undissolved contaminants from a polymer solution via a precipitation process at a temperature and pressure at which the polymer remains dissolved in the fluid solvent. In an embodiment of the present invention, the precipitation process applies a force to the undissolved contaminants, causing them to move uniformly in the direction of the force. Typically, the applied precipitation force is gravity, but may also be centrifugal, centripetal, or some other force. The amount of force applied and the duration of the precipitation time 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 precipitation process can be calculated using the following equation: ν=2gr 2 (ρ p -ρ f ) / 9η is the relationship between the aforementioned parameters and the settling velocity, which is a measure of the rate at which pollutants settle, where ν is the settling velocity and ρ p is the density of the pollutant particles, and ρ f is the density of the fluid or solution, g is the acceleration due to an applied force (typically gravity), r is the radius of the contaminant particle, and η is the dynamic viscosity of the fluid or solution. Some of the important parameters that determine the solution viscosity are the chemical composition of the fluid solvent, the MW of the polymer dissolved in the fluid solvent, the concentration of the dissolved polymer in the fluid solvent, the temperature of the fluid solvent solution, and the pressure of the fluid solvent solution.

[0233] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / fluid solvent solution at a temperature and pressure such that the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / fluid solvent solution at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / fluid solvent solution at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating 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).

[0234] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution at a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0235] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0236] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution at a pressure of about 800 psig (5.52 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer includes precipitating contaminants from a polyethylene / n-pentane solution under a pressure of from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0237] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution in which polyethylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polyethylene / n-pentane solution in which polyethylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 12%.

[0238] In an embodiment of the present invention, a method for purifying recycled polymers includes precipitating contaminants from a polypropylene / fluid solvent solution at a temperature and pressure such that the polypropylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers includes precipitating contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers includes precipitating contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers includes precipitating contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers includes precipitating contaminants from a polypropylene / n-butane solution at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the invention, a method for purifying recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution under a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the invention, a method for purifying recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0239] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 12%.

[0240] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes precipitating contaminants from a polypropylene / propane solution under a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0241] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 12%.

[0242] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / fluid solvent solution at a temperature and pressure such that the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the invention, a method for purifying reclaimed polymer comprises precipitating contaminants from a polystyrene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the invention, a method for purifying reclaimed polymer comprises precipitating 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).

[0243] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / n-butane solution in which polystyrene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a polystyrene / n-butane solution in which polystyrene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the invention, the polystyrene is dissolved at a weight percent concentration of up to 12%.

[0244] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure such that the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying reclaimed polymer comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution containing a solid medium at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0245] In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 20%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 18%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 16%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 14%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 12%.

[0246] In an embodiment of the invention, a method for purifying reclaimed polymer includes precipitating 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 containing precipitated polymer, at least one dissolved contaminant, and a lesser amount of at least one suspended contaminant.

[0247] In an embodiment of the present invention, the temperature in the precipitation step is about 110° C. to about 220° C. In an embodiment of the present invention, the pressure in the precipitation step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0248] mechanical filtration For purposes of this invention, unless otherwise specified, the term "filtration" refers to "mechanical filtration" or "adsorption filtration," or includes both types of filtration. A typical filtration system includes a filter medium, a filter vessel, a filter inlet, and a filter outlet. The filter medium contains filter particles contained within the filter vessel. The filter inlet is in fluid communication with the filter vessel and conveys a filtrate feed stream within the filter vessel, and the filter outlet is in fluid communication with the filtration system and conveys a filtrate stream from the filter vessel. A filtration system can include one or more filter mediums, filter vessels, and filter inlets and outlets in series or parallel. Furthermore, filtration systems can operate in radial or axial flow, or in upflow, downflow, or crossflow. A non-limiting example of a radial flow filter is a candle filter. Furthermore, filtration can be depth or surface filtration, based on a mechanical mode of action. A non-limiting example of a mechanical mode of action is particle size rejection, where suspended (dispersed) contaminants are retained by the filter media and separated from the filtered feed stream because the size of the suspended (dispersed) contaminants is larger than the pores of the filter media. As described, particle size rejection is an inter-particle phenomenon.

[0249] Filter media used in depth filtration include aggregates of filter particles that can be either homogeneous or heterogeneous. The filter particles can be uniformly or heterogeneously distributed within the filter medium (e.g., multiple layers of different filter particles). The filter particles forming the filter medium also need not be identical in shape or size and can be provided in either a separate or interconnected form. For example, the filter medium may include filter particles that can be either loosely associated or partially or fully bonded together by a polymeric binder or other means to form a unitary structure.

[0250] Filter particles may also be provided in a variety of shapes and sizes. For example, without limitation, filter particles may be provided in simple forms such as powders, granules, fibers, and beads. Filter particles can be provided in the shapes of spheres, polyhedrons, and cylinders, as well as other symmetrical, asymmetrical, and irregular shapes. Furthermore, filter particles can also be formed into complex forms such as webs, screens, meshes, nonwovens, woven fabrics, and bonded blocks, which may or may not be formed from the above simple forms. Filter particles can vary in size from shapeless filter particles (e.g., very fine powders) to filter particles with palpable shapes. Furthermore, the size of filter particles need not be uniform among filter particles used in any single filtration system. In fact, it may be desirable to provide filter particles with different sizes in a single filter.

[0251] In an embodiment of the present invention, the size of the filter particles varies from about 0.1 mm to about 10 mm. In an embodiment of the present invention, the size of the filter particles varies from about 10 mm to about 8 mm. In an embodiment of the present invention, the size of the filter particles varies from about 100 mm to about 5 mm. In an embodiment of the present invention, the size of the filter particles varies from about 1 mm to about 4 mm. In an embodiment of the present invention, the size of the filter particles varies between about 10 μm and about 100 μm. For spherical and cylindrical particles (e.g., fibers, beads, etc.), the above-mentioned dimensions refer to the diameter of the filter particles. For filter particles having substantially different shapes, the above-mentioned dimensions refer to the largest dimension (e.g., length, width, or height).

[0252] Non-limiting examples of filter particles include silicon oxide (silica), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, amorphous volcanic glass, recycled glass, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, fuller's earth, bentonite clay, metal organic framework (MOF), covalent organic framework (COF), zeolitic imidazolate framework (ZIF), cellulose, lignocellulose, anthracite, carbon black, coke, and activated carbon. In an embodiment of the present invention, the filter particles are selected from the group consisting of silica, activated alumina, silica gel, volcanic glass, fuller's earth, bentonite clay, and mixtures thereof. In an embodiment of the present invention, the filter particles are selected from the group consisting of activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In an embodiment of the invention, the filter particles are selected from the group consisting of MOFs, COFs, ZIFs, activated carbon, activated alumina, and mixtures thereof. In an embodiment of the invention, the filter particles are selected from the group consisting of diatomaceous earth, activated alumina, and mixtures thereof.

[0253] Non-limiting examples of filter media used in surface filtration include filter granules, porous ceramics, filter paper, filter cloth, plastic membranes, screens, nonwoven fabrics, woven fabrics, porous frit / sintered metal, and thin layers of perforated plates. In typical surface filtration, retained contaminants form a cake on the filter media that increases in thickness as filtration progresses. Typically, the filter cake creates an unsustainable pressure drop and must be removed after a certain filtration time by either mechanical action or backflushing. In an embodiment of the present invention, the filter media used in surface filtration is selected from the group consisting of a thin layer of diatomaceous earth particles (typically called a sock) deposited on a woven metal porous core. The porous core supports the filter media while allowing the filtration feed stream to pass through. Non-limiting examples of cores are perforated tubes and screen sleeves.

[0254] Filter aids may be used in filtration. Non-limiting examples of filter aids include diatomaceous earth (also called kieselguhr), cellulose, and perlite. These filter aids can be used as precoats on the filter medium or added to the filtration feed stream. In the latter case (also called body feed), the filter aid increases the porosity of the cake formed on the filter medium, thereby reducing the pressure drop through the cake during filtration.

[0255] At the end of a filter's useful life, the filter can either be removed from service and replaced with a new one, or regenerated. Non-limiting examples of regeneration are backflushing, thermal regeneration, and solvent regeneration.

[0256] In an embodiment of the present invention, the surface filter comprises a candle filter. In an embodiment of the present invention, the candle filter comprises a thin layer of diatomaceous earth deposited on a woven metal porous core. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is about 1 mm to about 20 mm. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is about 2 mm to about 10 mm. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is about 3 mm to about 5 mm.

[0257] The permeability of a filter medium is measured (as is well known to those skilled in the art) by passing a fluid stream through the medium and measuring the flow rate and pressure drop. The unit of measurement is millidarcy (mD), where 1 mD is equivalent to the passage of 1 mL of fluid having a viscosity of 1 mPa.s (1 cP) through a cross-sectional area of ​​1 cm in 1 second under 1 atmosphere of pressure. 2 and corresponds to passing through a filter medium having a thickness of 1 cm. In an embodiment of the present invention, the permeability of the diatomaceous earth filter medium is about 30 mD to about 20,000 mD. In an embodiment of the present invention, the permeability of the diatomaceous earth filter medium is about 400 mD to about 8,000 mD. In an embodiment of the present invention, the permeability of the diatomaceous earth filter medium is about 1,000 mD to about 4,000 mD. In an embodiment of the present invention, the permeability of the diatomaceous earth filter medium is about 2,300 mD to about 3,400 mD.

[0258] In an embodiment of the present invention, the diatomaceous earth filter medium retains suspended particles having a diameter greater than about 0.3 μm. In an embodiment of the present invention, the diatomaceous earth filter medium retains suspended particles having a diameter greater than about 0.8 μm. In an embodiment of the present invention, the diatomaceous earth filter medium retains suspended particles having a diameter greater than about 1 μm. In an embodiment of the present invention, the diatomaceous earth filter medium retains suspended particles having a diameter greater than about 1.7 μm. In an embodiment of the present invention, the diatomaceous earth filter medium retains suspended particles having a diameter greater than about 4 μm.

[0259] In an embodiment of the present invention, the candle filter comprises a thin diatomaceous earth filter medium deposited on a woven metal core, the diatomaceous earth filter medium having a thickness of about 2 mm to about 10 mm, a permeability of about 2,300 mD to 3,400 mD, and a retention capacity of suspended particles having a diameter greater than about 1.7 μm.

[0260] In an embodiment of the present invention, a method for purifying recycled polymers includes filtering contaminants from a polyethylene / fluid solvent solution at a temperature and pressure such that the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers includes filtering contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the temperature during the filtration step is about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers includes filtering contaminants from a polyethylene / fluid solvent solution at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, the pressure during the filtration step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0261] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers 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 an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes filtering contaminants from a polyethylene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0262] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

[0263] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution under a pressure of from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0264] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution in which polyethylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polyethylene / n-pentane solution in which polyethylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, polyethylene is dissolved at a weight percent concentration of up to 12%.

[0265] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes filtering contaminants from a polypropylene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0266] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 12%.

[0267] In an embodiment of the present invention, a method for purifying recycled polymers includes filtering contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers includes filtering contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers includes filtering contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers 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 an embodiment of the present invention, a method for purifying recycled polymers 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 an embodiment of the present invention, a method for purifying recycled polymer includes filtering contaminants from a polypropylene / propane solution under a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0268] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 12%.

[0269] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polystyrene / fluid solvent solution at a temperature and pressure such that the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises filtering contaminants from a polystyrene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises filtering contaminants from a polystyrene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

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

[0271] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure such that the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In an embodiment of the invention, a method for purifying reclaimed polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the invention, a method for purifying reclaimed polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the invention, a method for purifying reclaimed polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0272] In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 20%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 18%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 16%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 14%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 12%.

[0273] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer containing contaminants, each contaminant having a concentration, the contaminants of the recycled polymer including at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) leaching the alkylphenols, bisphenols, dioxins, PCBs, or phthalates from the recycled polymer at a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm in multiple leaching stages using a leaching solvent for a total residence time and a residence time for each leaching stage, with an average removal efficiency, to produce a leached polymer each containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates having a concentration, the average removal efficiency being greater than about 55%; and c) leaching the leached polymer to a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm in multiple leaching stages for a total residence time and a residence time for each leaching stage, with an average removal efficiency of at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, with an average removal efficiency of at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, the average removal efficiency being greater than about 55%. extracting the polymer with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of about 0°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 an extracted polymer; and d) dissolving the extracted polymer in a solvent selected from the group consisting of 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 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a dissolved polymer, at least one e) precipitating 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 containing the precipitated polymer, the at least one dissolved contaminant, and a lesser amount of the at least one suspended contaminant; f) precipitating the second 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 containing the precipitated polymer, the at least one dissolved contaminant, and a lesser amount of the at least one suspended contaminant;and filtering by mechanical filtration under a pressure of 0.05 MPa to produce a third solution containing the filtered polymer, at least one dissolved contaminant, and a further lesser amount of at least one suspended contaminant.

[0274] In an embodiment of the present invention, a method for purifying recycled polymer includes: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer including contaminants, each contaminant having a concentration, the contaminants of the recycled polymer including at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate; and b) purifying the recycled polymer. c) leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate from the recycled polymer in a non-densified state to produce a surface-cleaned polymer, the surface cleaning resulting in a reduction of loosely bound surface contaminants by greater than about 80%; and c) leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate from the recycled polymer in multiple leaching stages at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and a residence time for each leaching stage, with an average removal efficiency. d) extracting the leached polymer with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of about 80°C to about 280°C and a pressure of about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) to produce an extracted polymer. e) dissolving the extracted 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; f) heating 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).g) precipitating 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 containing the filtered polymer, at least one dissolved contaminant, and an even smaller amount of at least one suspended contaminant.

[0275] Adsorption filtration In an embodiment of the present invention, a method for purifying polyethylene includes contacting a contaminated polymer solution with a solid medium at a temperature and pressure such that the polymer remains dissolved in the fluid solvent. The solid medium of the present invention, also referred to throughout the present invention as an adsorption medium or adsorbent filter medium, is any solid material that contains solid medium particles and removes at least a portion of the contamination from a solution of recycled polyethylene dissolved in the fluid solvent of the present invention. Without being bound by theory, applicants believe that the solid medium removes contamination through a variety of mechanisms. Non-limiting examples of possible mechanisms include adsorption, absorption, electrostatics, size exclusion, ion exclusion, ion exchange, and other mechanisms that may be apparent to those skilled in the art. Furthermore, pigments and other contaminants commonly found in recycled polyethylene may be polar compounds or may have polar compounds on their surfaces, and therefore may preferentially interact with the solid medium (which may also have at least a slight polarity). This polar-polar interaction is particularly favorable when a nonpolar solvent (e.g., alkanes) is used as the fluid solvent.

[0276] In an embodiment of the present invention, the solid medium is selected from the group consisting of inorganic materials, carbonaceous materials, or mixtures thereof. Useful examples of inorganic materials include silicon oxide, aluminum oxide, iron oxide, 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 carbonaceous materials include anthracite, carbon black, coke, activated carbon, cellulose, and mixtures thereof. In an embodiment of the present invention, the solid medium is recycled glass. In an embodiment of the present invention, the solid media particles are selected from the group consisting of silicon oxide (silica), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, fuller's earth, bentonite clay, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), zeolitic imidazolate frameworks (ZIFs), cellulose, and lignocellulose. In an embodiment of the present invention, the solid media are selected from the group consisting of silica, activated alumina, silica gel, fuller's earth, bentonite clay, and mixtures thereof. In an embodiment of the present invention, the solid media are selected from the group consisting of activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In an embodiment of the present invention, the solid media are selected from the group consisting of MOFs, COFs, ZIFs, activated carbon, activated alumina, and mixtures thereof. In an embodiment of the present invention, the solid media are selected from the group consisting of diatomaceous earth, activated alumina, and mixtures thereof.

[0277] A non-limiting example of a physical mode of action is physical adsorption (also called physisorption), in which dissolved contaminants are adsorbed onto the outer surface of filter particles or the inner surface of pores by van der Waals forces and 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 filter particles by electrostatic attraction. Filter particles and filter media that remove contaminants primarily by adsorption are called adsorbent filter particles and adsorbent filter media, respectively.

[0278] The adsorptive filter media is typically housed in a cylindrical filter vessel as either a loose medium or a bonded block, and adsorptive filtration can be either axial or radial flow. The cylindrical adsorptive filter media has an aspect ratio, defined as the ratio of the height to the diameter of the cylindrical adsorptive filter media. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 1 or greater. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 2 or greater. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 5 or greater. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 10 or greater. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 30 or greater. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 50 or greater. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorptive filter media is about 70 or greater.

[0279] In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 5 cm or more. In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 20 cm or more. In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 50 cm or more. In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 1 m or more. In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 1.5 m or more. In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 3 m or more. In an embodiment of the present invention, the height of the cylindrical adsorptive filter medium is about 6 m or more.

[0280] In an embodiment of the present invention, the adsorptive filter medium is cylindrical in shape, the filter medium comprises loose adsorptive filter particles, the height of the cylindrical adsorptive medium is about 122 cm, the diameter of the cylindrical adsorptive medium is about 1.7 cm, the adsorptive filter particles comprise activated alumina, and the particle size of the adsorptive filter particles is 7x14 mesh.

[0281] In an embodiment of the present invention, the solid medium is contacted with the polymer in a vessel with stirring for a predetermined period of time. In an embodiment of the present invention, the solid medium is removed from the higher purity polymer solution via a solid-liquid separation process. Non-limiting examples of solid-liquid separation processes include filtration, decantation, centrifugation, and sedimentation. In an embodiment of the present invention, the contaminated polymer solution is passed through a fixed bed of solid medium. In an embodiment of the present invention, the solid medium is replaced as needed to maintain the desired purity of the polymer. In an embodiment of the present invention, the solid medium is regenerated and reused in the purification process. In an embodiment of the present invention, the solid medium is regenerated by fluidizing the solid medium during a re-washing process.

[0282] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / fluid solvent solution with a solid medium at a temperature and pressure such that the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting the polyethylene / fluid solvent with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting the polyethylene / fluid solvent with a solid medium at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting the polyethylene / fluid solvent with a solid medium at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting the polyethylene / fluid solvent with a solid medium at a pressure of about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0283] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0284] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution, in which polyethylene is dissolved at a mass percent concentration of at least 0.5%, with a solid medium. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-butane solution, in which polyethylene is dissolved at a mass percent concentration of up to 20%, with a solid medium. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

[0285] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer includes contacting a polyethylene / n-pentane solution with a solid medium under a pressure of from about psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0286] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a solid medium with a polyethylene / n-pentane solution in which polyethylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a solid medium with a polyethylene / n-pentane solution in which polyethylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a weight percent concentration of up to 12%.

[0287] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In an embodiment of the present invention, a method for purifying recycled polymer includes contacting a polypropylene / n-butane solution with a solid medium under a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0288] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution, in which polypropylene is dissolved at a weight percent concentration of at least 0.5%, with a solid medium. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / n-butane solution, in which polypropylene is dissolved at a weight percent concentration of up to 20%, with a solid medium. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 12%.

[0289] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises contacting a polypropylene / propane solution with a solid medium under a pressure of from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0290] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a solid medium with a polypropylene / propane solution in which polypropylene is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a solid medium with a polypropylene / propane solution in which polypropylene is dissolved at a weight percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a weight percent concentration of up to 12%.

[0291] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / fluid solvent solution with a solid medium at a temperature and pressure such that the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0292] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / n-butane solution, in which polystyrene is dissolved at a weight percent concentration of at least 0.5%, with a solid medium. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a polystyrene / n-butane solution, in which polystyrene is dissolved at a weight percent concentration of up to 20%, with a solid medium. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 18%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 16%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 14%. In an embodiment of the present invention, polystyrene is dissolved at a weight percent concentration of up to 12%.

[0293] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a poly(dimethylsiloxane) / fluid solvent solution with a solid medium at a temperature and pressure such that the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying reclaimed polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0294] In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a solid medium with a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 0.5%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 1%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 2%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 3%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 4%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a weight percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying recycled polymers comprises contacting a solid medium with a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 20%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 18%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 16%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 14%. In an embodiment of the invention, poly(dimethylsiloxane) is dissolved at a weight percent concentration of up to 12%.

[0295] In an embodiment of the present invention, a method for purifying recycled polymer is disclosed. The method includes: a) obtaining a recycled polymer, the recycled polymer selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer containing contaminants, each contaminant having a concentration, the contaminants in the recycled polymer including at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) leaching the alkylphenols, bisphenols, dioxins, PCBs, or phthalates from the recycled polymer at a temperature below the first melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm, using a leaching solvent in multiple leaching stages for a total residence time and for each residence time of the leaching stage, with an average removal efficiency, to produce a leached polymer each containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates having a concentration, the average removal efficiency being greater than about 55%; and c) leaching the leached polymer at a temperature of about 80° C. to about 280° C. and extracting the polymer with a first fluid solvent having a normal boiling point of less than about 70°C at a pressure of about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) to produce an extracted polymer; and d) dissolving the extracted polymer in a solvent selected from the group consisting of the first fluid solvent, the second fluid solvent, and mixtures thereof at a temperature of 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 dissolved polymer, at least one dissolved contaminant. e) precipitating 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 containing the precipitated polymer, the at least one dissolved contaminant, and a lesser amount of the at least one suspended contaminant; f) precipitating the second 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 containing the precipitated polymer, the at least one dissolved contaminant, and a lesser amount of the at least one suspended contaminant;g) filtering the third solution by adsorptive filtration at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution containing the filtered polymer.

[0296] In an embodiment of the present invention, a method for purifying recycled polymer is disclosed, the method comprising: a) obtaining a recycled polymer, the recycled polymer being selected from the group consisting of post-consumer recycled (PCR) polymer, post-industrial recycled (PIR) polymer, and combinations thereof, the recycled polymer containing contaminants, each contaminant having a concentration, the contaminants of the recycled polymer including at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate; and b) surface washing the recycled polymer in a non-densified state to obtain a surface-washed polymer. c) leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate from the reclaimed polymer at an average removal efficiency at a temperature below the primary melting point of the reclaimed polymer and at a pressure of about atmospheric to about 1,000 atm using a leaching solvent in multiple leaching stages over a total residence time and a residence time for each leaching stage, each having a concentration of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate. producing a leached polymer comprising at least one of tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, wherein the average removal efficiency is greater than about 55%; and d) extracting the leached polymer with a first fluid solvent having a normal boiling point 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 an extracted polymer. e) dissolving the extracted 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; and f) heating 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).g) 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 containing the filtered polymer, at least one dissolved contaminant, and an even smaller amount of at least one suspended contaminant; and h) 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 containing the twice-filtered polymer.

[0297] In an embodiment of the present invention, the temperature in the extraction step, dissolution step, precipitation step, and filtration step is about 110° C. to about 220° C. In an embodiment of the present invention, the pressure in the dissolution step, precipitation step, and filtration step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0298] separation In an embodiment of the present invention, a method for purifying recycled polymer includes separating a higher purity polymer from a fluid solvent under a temperature and pressure at which the polymer precipitates out of solution and is no longer soluble in the fluid solvent. In an embodiment of the present invention, precipitation of the higher purity polymer from the fluid solvent is achieved by reducing the pressure at a fixed temperature. In an embodiment of the present invention, precipitation of the higher purity polymer from the fluid solvent is achieved by reducing the temperature at a fixed pressure. In an embodiment of the present invention, precipitation of the higher purity polymer from the fluid solvent is achieved by increasing the temperature at a fixed pressure. In an embodiment of the present invention, precipitation of the higher purity polymer from the fluid solvent is achieved by reducing both the temperature and the pressure. The solvent can be partially or completely converted from a liquid to a vapor phase by controlling the temperature and pressure. In an embodiment of the present invention, the precipitated polymer is separated from the fluid solvent without completely converting the fluid solvent to a 100% vapor phase by controlling the temperature and pressure of the solvent during the separation process. Separation of the precipitated higher purity polymer is achieved by any method of liquid-liquid or liquid-solid separation. Non-limiting examples of liquid-liquid or liquid-solid separation include filtration, decantation, centrifugation, and sedimentation.

[0299] In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / fluid solvent solution at a temperature and pressure at which the polyethylene precipitates from the solution. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 0°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 50°C to about 175°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 4,000 psig (27.58 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0300] In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-pentane solution at a temperature of about 0°C to about 280°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-pentane solution at a temperature of about 30°C to about 150°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-pentane solution at a temperature of about 50°C to about 130°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polyethylene from a polyethylene / n-pentane solution under a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0301] In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / fluid solvent solution at a temperature and pressure such that the polypropylene precipitates from the solution. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 100°C to about 200°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0302] In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / propane solution at a temperature of about -42°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / propane solution at a temperature of about 0°C to about 150°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / propane solution at a temperature of about 50°C to about 130°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / propane solution at a pressure of about 0 psig (0 MPa) to about 6,000 psig (41.37 MPa). In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polypropylene from a polypropylene / propane solution at a pressure of about 50 psig (0.34 MPa) to about 3,000 psig (20.68 MPa). In an embodiment of the present invention, a method for purifying recycled polymer comprises separating polypropylene from a polypropylene / propane solution under a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0303] In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polystyrene from a polystyrene / fluid solvent solution at a temperature and pressure at which the polystyrene precipitates from the solution. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 100°C to about 200°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the invention, a method for purifying recycled polymer comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0304] In an embodiment of the present invention, a method for purifying recycled polymers comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure such that the poly(dimethylsiloxane) precipitates from the solution. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 200°C. In an embodiment of the present invention, a method for purifying recycled polymers comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 180°C. In an embodiment of the present invention, a method for purifying reclaimed polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 0 psig (0 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,000 psig (6.89 MPa). In an embodiment of the present invention, a method for purifying reclaimed polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 500 psig (3.45 MPa).

[0305] In an embodiment of the invention, the filtered polymer is separated 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 2,000 psig (13.79 MPa).

[0306] IX. Test Methods The test methods described herein are used to measure the effectiveness of various methods for purifying polymers. Specifically, the described methods demonstrate the effectiveness of a given purification method in improving color and translucency / clarity (i.e., bringing the color and opacity of recycled polymer closer to that of colorless, unrecycled polymer), reducing or eliminating elemental contamination (i.e., removing heavy metals), reducing or eliminating non-combustible contamination (i.e., inorganic fillers), reducing or eliminating volatile compounds (especially those that contribute to the malodor of recycled polymers), and reducing or eliminating polymer contamination (i.e., polyethylene contamination in polypropylene).

[0307] Color and opacity measurements The color and opacity / translucency of a polymer are important parameters that determine whether the polymer can achieve the desired visual aesthetics of the article made from that polymer. Recycled polymers, especially PCR polymers, are typically dark and opaque due to residual pigments, fillers, and other contaminants. Therefore, color and opacity measurements are important parameters for determining the effectiveness of a polymer purification method.

[0308] Prior to color measurements, samples of either polymer powder or pellets were pressed into a mold to form a square test specimen measuring 30 mm wide x 30 mm long x 1 mm thick (with rounded corners). Powder samples were first densified at room temperature (approximately 20-23 °C) by cold-pressing the powder into a sheet between stainless steel platens using clean, unused aluminum foil as a contact release layer. Approximately 0.85 g of either the cold-pressed powder or pellets was then pressed into a test specimen in a Carver Press Model C (Carver, Inc., Wabash, IN 46992-0554 USA) preheated to 200 °C using the aluminum platens, unused aluminum foil release layer, and a stainless steel shim with a cavity corresponding to the square test specimen dimensions described above. The samples were heated for 5 minutes before pressure was applied. After 5 minutes, the press compressed the specimen with a hydraulic pressure of at least 2 tons (1.81 metric tons) for at least 5 seconds before releasing. The laminate was then removed from the mold and cooled between two thick, flat metal heat sinks. The aluminum foil contact release layer was then peeled from the sample and discarded. The flashing around the periphery of the sample on at least one side was peeled back to the edge of the mold before the sample was then ejected from the mold. Each test specimen was visually evaluated for void / bubble defects, and only samples without defects in the color measurement area (minimum diameter 0.7 inches (17.78 mm)) were used for color measurements.

[0309] The color of each sample is based on the International Commission on Illumination (CIE) L * , a * , b * It was characterized using the three-dimensional color space of L * The dimension is a measure of the lightness of the sample, L * = 0 corresponds to the darkest black sample, and L * = 100 corresponds to the brightest white sample. * is a measure of the red or green color of the sample, and a * Positive values ​​of correspond to red, and a * Negative values ​​of correspond to green. * is the measured value of blue or yellow of the sample, and b* Positive values ​​of correspond to yellow, and b * A negative value corresponds to blue. The L of each square test specimen sample, 30 mm wide x 30 mm long x 1 mm thick, * a * b * Values ​​were measured on a Hunter Lab model LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-5280, USA) configured with D65 as the standard illuminant, a 10° observation angle, a field area diameter of 1.75 inches (44.45 mm), and a port diameter of 0.7 inches (17.78 mm).

[0310] The opacity of each sample is a measure of how much light passes through the sample (i.e., a measure of the sample's translucency) and was determined using the Hunter Lab spectrophotometer described above in contrast ratio opacity mode. To determine the opacity of each sample, two measurements were taken: the lightness value Y of the sample backed with a white backing; 白色背景 The other is to measure the brightness value Y of the sample backed with a black backing. 黒色背景 The opacity was then calculated from the lightness values ​​using the following formula:

[0311]

number

[0312] elemental analysis Many recycled polymers have unacceptably high levels of heavy metal contamination. The presence of heavy metals, such as lead, mercury, cadmium, and chromium, can prevent the use of recycled polymers in certain applications, such as food or drug contact applications or medical device applications. Therefore, measuring the concentration of heavy metals is important in determining the effectiveness of polymer purification methods.

[0313] Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Test solutions were prepared by combing approximately 0.25 g of sample with 4 mL of concentrated nitric acid and 1 mL of concentrated hydrofluoric acid (HF), ranging from 2 to 6, depending on sample availability. Samples were digested using an Ultrawave microwave sample digestion protocol consisting of a 20-minute ramp to 125 °C, a 10-minute ramp to 250 °C, and a 20-minute hold at 250 °C. The digested sample was allowed to cool to room temperature. 0.25 mL of 100 ppm Ge and Rh were added to the digested sample as internal standards, and then the sample was diluted to 50 mL. To assess measurement accuracy, a pre-digestion spike was prepared by spiking a non-regenerated polymer. The virgin polymer spike samples were weighed using the same procedure as described above and spiked with the appropriate amount of each single-element standard of interest (including Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb). Spikes were prepared at two different levels: a "low spike" and a "high spike." Each spike was prepared in triplicate. In addition to the virgin polymer spikes, blanks were also spiked to ensure no errors occurred during pipetting and to track recovery throughout the process. Blank spike samples were also prepared in triplicate at two different concentrations and treated in the same manner as the spiked virgin polymer and test samples. 0.05, 0.1, 0.5, 1, 5, 10, 50, 100, and 500 ppb solutions containing Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb were prepared to generate a nine-point calibration curve. All calibration standards were prepared by diluting the undiluted standard reference solution with 0.25 mL of 100 ppm Ge and Rh as internal standards, 4 mL of concentrated nitric acid, and 1 mL of concentrated HF. The prepared standards, test samples, and spiked test samples were analyzed using an Agilent 8800 ICP-QQQMS, optimized according to the manufacturer's recommendations.The observed m / z for each analyte and the collision cell gases used for analysis were as follows: Na, 23 m / z, H; Al, 27 m / z, H; Ca, 40 m / z, H; Ti, 48 m / z, H; Cr, 52 m / z, He; Fe, 56 m / z, H; Ni, 60 m / z, no gas; Cu, 65 m / z, no gas; Zn, 64 m / z, He; Cd, 112 m / z, H; Pb, sum of 206 ≥ 206, 207 ≥ 207, and 208 ≥ 208 m / z, no gas; Ge, 72 m / z, all modes; Rh, 103 m / z, all modes. Ge was used as the internal standard for all elements below 103 m / z, and Rh was used as the internal standard for all elements above 103 m / z.

[0314] residual ash Many recycled polymers contain various fillers, such as calcium carbonate, talcum, and glass fibers. These fillers, while useful in the recycled polymer's original use, alter the polymer's physical properties in ways that may be unwanted in the recycled polymer's subsequent use. Thus, measuring the amount of filler is important in determining the effectiveness of a polymer purification method.

[0315] Thermogravimetric analysis (TGA) was performed to determine the amount of non-combustible material (sometimes referred to as ash) in the samples. Approximately 5-15 mg of sample was loaded into a platinum sample pan and heated to 700 °C at a rate of 20 °C / min in an air atmosphere in a TA Instruments Model Q500 TGA instrument. The sample was held isothermally at 700 °C for 10 minutes. After the isothermal hold, the residual mass percentage was measured at 700 °C.

[0316] Odor analysis Odor sensory analysis was performed by placing approximately 3 g of each sample in a 20 mL glass vial and allowing the sample to equilibrate at room temperature for at least 30 minutes. After equilibration, each vial was opened and trained evaluators smelled the headspace (bunny sniff) to determine odor intensity and descriptor profile. Odor intensity was rated according to the following scale: 5 = very strong, 4 = strong, 3 = moderate, 2 = weak to moderate, 1 = weak, and 0 = no odor.

[0317] Polymer Contamination Analysis Many recycled polymers, especially those derived from mixed stream sources, may contain unwanted polymer contamination. Without being bound by any theory, polymer contamination, such as polyethylene contamination in polypropylene, can affect the physical properties of the polymer by creating heterogeneous phases and weakening the resulting interfaces. Furthermore, polymer contamination can also increase the opacity of the polymer and affect its color. Therefore, measuring the amount of polymer contamination is important in determining the effectiveness of a polymer purification method.

[0318] Differential scanning calorimetry (DSC) was used to assess the presence of semicrystalline polymer contamination. For example, to measure the amount of polyethylene contamination in polypropylene, a set of five polypropylene / polyethylene blends was prepared containing 2, 4, 6, 8, and 10 wt.% Formolene® HB5502F HDPE (Formosa Plastics Corporation, USA) in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, BV). Approximately 5-15 mg of each sample was sealed in an aluminum DSC pan and analyzed on a TA Instruments Model Q2000 DSC using the following method: 1. Equilibrate at 30.00°C 2. Ramp to 200.00°C at 20.00°C / min 3. Mark the end of cycle 0 4. Decrease temperature at 20.00°C / min to 30.00°C 5. Mark the end of cycle 1 6. Ramp to 200.00°C at 20.00°C / min. 7. Mark the end of cycle 2 8. Decrease temperature at 20.00°C / min to 30.00°C 9. Mark the end of cycle 3 10. Ramp to 200.00°C at 5.00°C / min. 11. Mark the end of cycle 4

[0319] The 5.00°C / min DSC thermograms were used to calculate the enthalpy of melting of the HDPE peak near 128°C for each sample of known HDPE content. Plotting the enthalpy of melting versus the known wt% HDPE concentration yielded the linear calibration curve shown in Figure 2.

[0320] Samples with unknown PE content were analyzed using the same DSC equipment and method described above. The PE content was calculated using the calibration curve described above. The specific HDPE used to generate the calibration curve will most likely have a different degree of crystallinity than the polyethylene (or polyethylene blend) contamination that may be present in the recycled polymer sample. Crystallinity may independently affect the measured enthalpy of fusion of the polyethylene and, therefore, the resulting polyethylene content calculation. However, the DSC test described herein is intended to be used as a relative indicator for comparing the effectiveness of various methods for purifying polymers and is not intended to precisely quantify the polyethylene content in polymer blends. While the above method describes the measurement of polyethylene contamination in polypropylene, it can also be applied to the measurement of other semicrystalline polymers using different temperature ranges and peaks in the DSC thermogram. Additionally, other methods, such as nuclear magnetic resonance (NMR) spectroscopy, can be used to measure the amount of both semicrystalline and amorphous polymer contamination in a sample.

[0321] Analytical measurement of chemical pollutants For pesticides, the EN 15662:2018-07 Modular QuEChERS method was applied. For alkylphenol ethoxylates, alkylphenols, and bisphenols, the following technique was applied: samples were cut, homogenized, and weighed. An internal standard (deuterated bisphenol A) was then added, and the samples were then extracted with hexane at room temperature. MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide) was added for derivatization, and contaminant levels were determined by GC-MSD. For dioxins, furans, and PCBs, the ISO / IEC 17025:2005 method was applied. The samples were cut into small pieces, and aliquots of the sample material were spiked with 13C / 12C-labeled PCDD / F internal standards. Extraction and disruption of the matrix with hexane and H2SO4 were performed for 1 hour, followed by re-extraction with hexane (three times for 30 minutes). A multi-step chromatographic cleanup was used. The measurement solution was spiked with 13C / 12C-labeled PCDD / F recovery standards, and quantification with internally labeled PCDD / F standards (isotope dilution and internal standard techniques) was performed. For organotins, the method followed the EDANA protocol (WSP 351) for organotin compounds in absorbent hygiene products and their constituent ingredients. More specifically, the samples were extracted with an ethanolic solution of sodium diethyldithiocarbamate, alkylated with sodium tetraethylborate, and transferred to the organic phase by extraction with hexane. Tetrasubstituted organotin compounds were then separated using capillary gas chromatography and verified using either an AED or MS as the detector. GC-ICP-MS was used as the detector system for organometallic analysis. For phthalates, samples were cut, homogenized, and weighed. Then, an internal standard and extraction with hexane at room temperature were used. The extracted phthalates were then identified and quantified by GC-MSD. For PAHs, samples were cut, homogenized, and weighed. Then, a deuterated PAH internal standard was added, and the sample was extracted with hexane. The extracted PAHs were further purified on silica gel, concentrated, and then characterized by GC-MSD.

[0322] Amount of loosely bound surface contamination The amount of loosely bound surface contamination was measured by the following method: Approximately 20 g of plastic was added to a 1,000 mL round-bottom flask. Approximately 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 approximately 60 seconds. The water was decanted from the flask. Approximately 600 mL of additional distilled water was added to the 1,000 mL flask and then immediately decanted, leaving behind the original reclaimed polymer containing a small amount of water. The reclaimed polymer was removed from the round-bottom flask and dried overnight at 60°C in a convection oven. The % mass change of the plastic is the amount of loosely bound surface contamination.

[0323] Color Measurement for ΔE Calculation Color measurements were made using a Minolta Spectrophotometer, Model CM580d. The "white" portion of the Leneta card was used as a common background and reference point for ΔE calculations. ΔE is the color difference between the sample color and the reference color. Color measurements were made using a D65 illuminant and a 10° observer. A minimum of three measurements were made for each compressed thermoplastic starch composition sample. The L, a, and b values ​​were averaged and reported along with the ΔE value. A pure white Leneta card has a ΔE value of 0, with positive deviations from 0 indicating increased discoloration. Those skilled in the art will know how to calculate the ΔE value. [Example]

[0324] Comparative Example 1 - Purification of Post-Commercial Film Using a Dissolution Recycling Process Using the method disclosed in Section IX and illustrated in Figure 4, samples from post-market recycled (PCR) films (referred to as input films) in which concentrations of 74 chemical contaminants were measured by GALAB Laboratories GmbH (Am Schleusengraben 7, 21029 Hamburg, Germany) were processed using the experimental setup illustrated in Figures 3A and 3B and the following procedure (Phasex Corporation, 125 Flagship Drive, North Andover, Massachusetts, USA). Thirty grams of input film was loaded into a 300 mL (working volume) autoclave equipped with an overhead mechanical stirrer. Air was removed from the autoclave headspace by three cycles of evacuation and N2 purge. The autoclave was then filled with n-butane, and its contents were equilibrated at an internal temperature of approximately 160 °C and a pressure of approximately 3,000 psig (20.7 MPa), i.e., extraction conditions. Under these extraction conditions, the material in the autoclave was in a two-phase regime: one phase (light or extract phase) containing n-butane and a small amount of a low-molecular-weight product film dissolved therein, and the other phase (heavy or raffinate phase) containing a large amount of a product film dissolved in n-butane. The autoclave material was then extracted twice using the experimental setup shown in Figure 3A and the following procedure: the autoclave material was stirred for approximately 10 minutes, then allowed to settle for approximately 10 minutes, and finally, n-butane was flushed through the autoclave through the expansion valve into the extract collection flask. The above extraction procedure was repeated once more. The remaining autoclave material was then dissolved in n-butane at dissolution conditions of approximately 160°C and approximately 4,700 psig (32.4 MPa), thus creating a one-phase system. The dissolved material was purified and recovered using the experimental setup of FIG. 3B and the following procedure: the autoclave material was stirred for approximately 60 minutes, then allowed to settle for approximately 60 minutes, and then the autoclave material was removed from the autoclave by opening the autoclave valve, passed through an axial flow filter with diatomaceous earth, an activated alumina column, an expansion valve, and collected in a product collection flask.The axial flow filter contained 23 g of diatomaceous earth (Celatom® FW-80, EP Minerals, LLC, Reno, NV) and was 1 in. (2.54 cm) long and 1 3 / 8 in. ID (3.5 cm). The activated alumina column had an ID of approximately 0.68 in. (1.73 cm) and a len...

Claims

1. 1. A method for purifying reclaimed polymer, comprising: 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, the recycled polymer comprising contaminants, each contaminant having a concentration, the contaminants in the recycled polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, or polycyclic aromatic hydrocarbons (PAHs); b. Leaching the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs from the recycled polymer at an average removal efficiency using a leaching solvent at a temperature below the primary melting point of the recycled polymer and at a pressure of about atmospheric to about 1,000 atm for a total residence time and for each residence time of the leaching stages to produce a leached polymer each containing a concentration of at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, or PAHs, wherein the average removal efficiency of the leached polymer is greater than about 55%; c) extracting the leached polymer with a first fluid solvent having a normal boiling point 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 an extracted polymer; d) dissolving the extracted 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; e. precipitating 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 precipitated polymer, at least one dissolved contaminant, and a lesser amount of the 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 filtered polymer, at least one dissolved contaminant, and a still smaller amount of the at least one suspended contaminant; g. filtering the third solution by adsorptive filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising filtered polymer; h. separating the filtered polymer from the fourth solution to produce a higher purity polymer with an average removal efficiency, the higher purity polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, each having a concentration, the second fluid solvent having the same or a different chemical composition as the first fluid solvent, and the average removal efficiency of the higher purity polymer is greater than about 75%; A method comprising:

2. 2. The method of claim 1, wherein the alkylphenols, bisphenols, dioxins, PCBs, and phthalates include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, or 2-ethylhexyl phthalate.

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

4. 4. The method of any one of claims 1 to 3, wherein the number of leaching stages is from about 1 to about 50.

5. The recycled polymer is about 1 mm －１ The method of any one of claims 1 to 4, wherein the surface area to volume ratio is greater than or equal to 1000 nm.

6. 6. The method of any one of claims 1 to 5, wherein the total residence time of the leaching step is less than about 360 minutes.

7. The leaching solvent is an organic solvent or a mixture of organic solvents, preferably, the leaching solvent is DME, diethyl ether, MEK, ethyl acetate, THF, acetone, methanol, CO ２ The method according to any one of claims 1 to 6, wherein the compound is at least one of:

8. The recycled polymer is surface washed in a non-densified state in one or more surface washing steps prior to the leaching step, the surface washing steps resulting in a reduction of loosely bound surface contamination by greater than about 80%, and the recycled polymer prior to the surface washing step has a density of about 1 mm －１ The method of any one of claims 1 to 7, wherein the surface area to volume ratio is greater than or equal to 1000 nm.

9. The recycled 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, the surface washing resulting in a reduction of loosely bound surface contamination by greater than about 80%, and the recycled polymer prior to surface washing has a particle size of about 1 mm. －１ 9. The method of claim 1, wherein the leaching step is carried out in a continuous stirred tank reactor (CSTR), the leaching solvent is ethyl acetate, the CSTR comprises three leaching stages, the leaching temperature is about 77°C, the leaching pressure is near atmospheric pressure, the residence time in each of the leaching stages is about 20 minutes, the average removal efficiency is greater than about 55%, and the leached polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets.

10. 10. The method of any one of claims 1 to 9, wherein the filtered polymer is separated 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 2,000 psig (13.79 MPa).

11. The method of any one of claims 1 to 10, wherein the extracted polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 0.5%.

12. The method according to any one of claims 1 to 11, wherein the regenerated polymer is a PCR polymer.

13. The method of any one of claims 1 to 12, wherein the recycled polymer is a homopolymer of polypropylene or a copolymer of predominantly polypropylene.

14. The method of any one of claims 1 to 13, wherein the recycled polymer is a homopolymer of polyethylene or a copolymer of predominantly polyethylene.

15. The fluid solvent has a normal boiling point of less than about 0° C. and greater than about −45° C. and a standard enthalpy change of vaporization of less than about +25 kJ / mol; preferably, the fluid solvent is at least one of an olefinic hydrocarbon, an aliphatic hydrocarbon, or a mixture thereof; more preferably, the aliphatic hydrocarbon is at least one of a C １ ~C ６ 15. The method according to any one of claims 1 to 14, wherein the hydrocarbon is at least one of an aliphatic hydrocarbon or a mixture thereof.

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