Method for purifying regenerated polymer

Abstract

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

Description

Technical Field

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

[0002] Synthetic polymers are ubiquitous in daily life due to their relatively low production costs and good material property balance. They are widely used in various applications, such as packaging, automotive parts, medical devices and consumer products. In order to meet the high requirements of these applications, hundreds of millions of tons of synthetic polymers are produced every year in the world. The vast majority of these polymers are produced by increasingly scarce fossil resources such as oil and natural gas. In addition, the manufacture of these synthetic polymers by fossil sources causes greenhouse gases (GHG), mainly CO2, to be discharged into the atmosphere.

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

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

[0005] Although recycled plastics are classified into mainly homogeneous streams and washed with aqueous and / or caustic solutions, the final reprocessed pellets are still highly polluted by unwanted waste impurities such as spoiled food residues and residual flavor components. In addition, due to the mixture of dyes and pigments commonly used for coloring plastic products, the recycled plastic pellets except those from recycled beverage containers are all dark. Although there are some applications that are insensitive to color and pollution (for example, black plastic paint containers and hidden motor vehicle parts), most applications require colorless pellets. The demand for high-quality "original ecology" recycled resins is particularly important for food and drug contact applications (such as food packaging). Except being polluted by impurities and mixed colorants, many recycled resin products are usually heterogeneous in chemical composition, and may contain a large amount of polymer contaminants, such as polyethylene (PE) pollution in recycled PP, and PP pollution in recycled polyethylene (PE).

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

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

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

[0009] Although pollution is problematic for all end-market applications, demanding applications have even more stringent requirements, especially for certain chemical pollutants. According to the chemical structure of the pollutant, the relevant chemical pollutants are divided into various chemical categories. Non-limiting examples of pollutants of these chemical categories are heavy metals, pesticides, dioxins, furans, polychlorinated biphenyls (PCBs), phthalates, polycyclic aromatic hydrocarbons (PAHs), organotin, bisphenols, isothiazolin, glyphosate, alkylphenols, alkylphenol ethoxylates, aromatic amines and flame retardants. In addition, the target levels of these pollutants may be extremely low. For example, the target level can be the order of magnitude of parts per million (ppm), parts per billion (ppb) and parts per trillion (ppt), wherein the initial contaminated plastic may contain 1,000 times the level of the target level. Therefore, it is usually necessary to reduce 1,000 times the chemical pollution.

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

[0011] U.S. Patent 10,022,725 discloses a mechanical recycling process for cleaning linear low density polyethylene (LLDPE) / LDPE film for recycling. The '725 patent also discloses the steps of shredding, a first water washing step, a second comminution step involving wet grinding, one or more friction washing steps using hot water in at least one step, drying or multiple drying steps, and a compacting step. The process may be quite effective in removing certain loosely bound surface contaminants, but will be ineffective in removing bulk contaminants because of the extremely low solubility of bulk contaminants in the aqueous washing medium and / or the limited diffusion rate of bulk contaminants within the plastic.

[0012] U.S. Patent 9,616,595 discloses a mechanical recycling process for de-inking surface printed plastic films. The '595 patent also discloses the steps of grinding, ink removal steps, general washing, cleaning solution recovery, pigment recovery and drying. The ink removal step involves the use of an aqueous cleaning fluid having a high pH and a selective cleaning agent such as lauryl sulfate and high turbulence. The process claims the ability to remove surface printed inks, which may cause chemical contamination after heating during the recycling process. The process will have limited ability to remove bulk contaminants due to limited solubility of the bulk contaminants in the aqueous washing medium and / or limited diffusion rate of the bulk contaminants in the plastic.

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

[0014] U.S. Patent 6,555,588 describes a method for producing a polypropylene blend from a plastic mixture containing other polymers. The '588 patent describes extracting contaminants from a polymer at a temperature below the solubility temperature of the polymer in a selected solvent such as hexane for a specified residence time. The '588 patent also describes increasing the temperature of the solvent (or a second solvent) to dissolve the polymer prior to filtering. The '588 patent also describes using shear or flow to precipitate polypropylene from solution. The polypropylene blend described in the '588 patent contains up to 5.6% by weight of polyethylene contaminants.

[0015] European Patent Application 849,312 (translated from German into English) describes a method for obtaining purified polyolefins from a plastic mixture containing polyolefins or a waste containing polyolefins. The '312 patent application describes extracting the polyolefin mixture or waste with a hydrocarbon fraction of a gasoline fuel or a diesel fuel having a boiling point above 90°C at a temperature between 90°C and the boiling point of the hydrocarbon solvent. The '312 patent application also describes contacting the hot polyolefin solution with bleaching clay and / or activated carbon to remove foreign components from the solution. The '312 patent also describes cooling the solution to a temperature below 70°C to crystallize the polyolefin, then removing the adhering solvent by heating the polyolefin to above the melting point of the polyolefin, or by evaporating the adhering solvent in a vacuum or passing a gas stream through the polyolefin to precipitate, and / or extracting the solvent with an alcohol or ketone having a boiling point below the melting point of the polyolefin.

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

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

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

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

[0020] U.S. Patent Application 2009 / 0178693 discloses a method for purifying plastics. The '693 patent application also discloses a multi-step process involving pelletizing to form plastic flakes, surface washing with supercritical CO2, surface washing and extraction with a high boiling point solvent or solvent mixture (such as limonene and ethylene lactic acid), a final surface washing with supercritical CO2 to remove the high boiling point solvent on the surface, and devolatilization. It is also disclosed that the plastic flake feed material is stirred with the solvent and the shape of the flakes is maintained. In addition, it is disclosed that the recovered material remains as flakes, which means that the process is completed at a temperature below the initial melting point of the plastic.

[0021] U.S. Patent No. 9,834,621 discloses a method for purifying polypropylene. The '621 patent further discloses contacting the regenerated 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 regenerated polypropylene; dissolving the extracted regenerated polypropylene in a solvent selected from the first fluid solvent, the second fluid solvent, and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a first solution comprising polypropylene, at least one dissolved contaminant, and at least one suspended contaminant; and dissolving the extracted regenerated polypropylene in a solvent selected from the first fluid solvent, the second fluid solvent, and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a first solution comprising polypropylene, at least one dissolved contaminant, and at least one suspended contaminant. The method is characterized in that the first solution is precipitated at a temperature of about 14 atm to about 544 atm and a pressure of about 14 atm to about 544 atm to produce a second solution comprising polypropylene, at least one dissolved contaminant and less at least one suspended contaminant; the second solution is filtered at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a third solution comprising purer polypropylene, at least one dissolved contaminant and even less at least one suspended contaminant; and the purer polypropylene is separated from the third solution; and wherein the second fluid solvent has the same chemical composition as the first fluid solvent or a different chemical composition. The above method is very suitable for removing contaminants. However, the ability to dissolve, settle and filter plastics is very difficult and may not be feasible or practical for plastics with high molecular weight (MW), such as those used in films and blow molded containers. In addition, the above method does not mention the removal of surface contaminants prior to extraction and dissolution, thereby increasing the burden of such disclosed methods, especially filtration.

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

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

[0024] In an embodiment of the present invention, a method for purifying a recycled polymer is disclosed. The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from a post-consumer recycled (PCR) polymer, a post-industrial recycled (PIR) polymer, and a combination thereof; and wherein the recycled polymer contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants contain at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates, and polycyclic aromatic hydrocarbons (PAHs); b) using a leaching solvent at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm in multiple leaching stages; wherein said pesticide, alkylphenol ethoxylate, alkylphenol, bisphenol, dioxin and dioxin-like compounds, PCB, metal, organotin, phthalate and PAH are leached from said recycled polymer with an average removal efficiency during the total residence time and the residence time of each of said leaching stages to produce a leached polymer comprising at least one of pesticide, alkylphenol ethoxylate, alkylphenol, bisphenol, dioxin and dioxin-like compounds, PCB, metal, organotin, phthalate and PAH, each having a certain concentration; and wherein said average removal efficiency of said leached polymer is greater than about 55%; c) at a temperature of about 80° C. to about 280° C. and about 150 psig (1.0 3MPa) to about 8,000psig (55.16MPa) of the first fluid solvent having a normal boiling point of less than about 70 ° C to produce an extracted polymer; d) dissolving the extracted polymer in a solvent selected from 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 200psig (1.38MPa) to about 9,000psig (62.05MPa) to produce a first solution comprising dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant; e) at a temperature of about 90 ° C to about 280 ° C and a pressure of about 200psig (1.38MPa) to about 9,000psig (62.05MPa) of the first fluid solvent having a normal boiling point of less than about 70 ° C to produce an extracted polymer; The invention relates to a method of preparing a first solution comprising: settling the first solution at a pressure of about 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant; f) filtering the second solution by mechanical filtration at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtered polymer, at least one dissolved contaminant, and even less of at least one suspended contaminant; g ...05MPa) by adsorptive filtration to produce a fourth solution comprising a filtered polymer; and h) separating the filtered polymer from the fourth solution to produce a purer polymer having an average removal efficiency; wherein the purer polymer comprises at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates, and PAHs, each having a certain concentration; wherein the second fluid solvent has the same chemical composition or a different chemical composition as the first fluid solvent; and wherein the average removal efficiency of the purer polymer is greater than about 75%. .

[0025] In an embodiment of the present invention, a method for purifying a regenerated polymer is disclosed.The method comprises: a) obtaining recycled polyethylene; wherein the recycled polyethylene is post-consumer recycled (PCR) polyethylene; and wherein the recycled polyethylene contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants contain at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates and polycyclic aromatic hydrocarbons (PAHs); b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; c) using ethyl acetate at a temperature of about 55° C. and about 65° C. and a pressure of about atmospheric pressure. leaching the pesticide, alkylphenol ethoxylate, alkylphenol, bisphenol, dioxin and dioxin-like compounds, PCB, metal, organotin, phthalate and PAH from the recycled polymer with an average removal efficiency within a total residence time in a countercurrent auger extraction to produce a leached polymer comprising at least one of the pesticide, alkylphenol ethoxylate, alkylphenol, bisphenol, dioxin and dioxin-like compounds, PCB, metal, organotin, phthalate and PAH, each having a concentration; wherein the average removal efficiency of the leached polymer is greater than about 90%; d) extracting the leached polymer with n-butane at a temperature of about 160° C. and a pressure of about 3,000 psig (20.7 MPa) to produce an leached polymer. e) dissolving the extracted polymer in n-butane at a temperature of about 160° C. and a pressure of about 4,700 psig (32.4 MPa) to produce a first solution comprising the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; f) settling the first solution at a temperature of about 160° C. and a pressure of about 4,700 psig (32.4 MPa) to produce a second solution comprising the settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant; g) filtering the 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 filtered polymer, at least one dissolved contaminant, and even less of at least one suspended contaminant. h) filtering the third solution by adsorptive filtration at a temperature of about 160° C. and a pressure of about 4,700 psig (32.4 MPa) by contacting the third solution with one or more solid media to produce a fourth solution comprising a twice filtered polymer; and i) separating the filtered polymer from the fourth solution to produce a purer polymer having an average removal efficiency; wherein the purer polymer comprises at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, and PAHs, each having a certain concentration; and wherein the average removal efficiency of the purer polymer is greater than about 95%. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0029] Figure 3A Schematic diagram of the experimental setup used in the extraction step of the dissolution recycling process.

[0030] Figure 3B Schematic diagram of the experimental setup used in the dissolution, sedimentation, filtration, and separation steps of the dissolution recycling process.

[0031] Figure 4 is a table with removal data from a dissolution recycling process alone, a submerged leaching process alone, and a combined process of submerged leaching and dissolution recycling. DETAILED DESCRIPTION

[0032] I. Definitions

[0033] As used herein, the term "plastic" refers to polymers such as polyethylene (PE), PP, PET, LLDPE, LDPE, HDPE, polyethylene copolymers, ethyl vinyl acetate copolymers (EVA), ethyl vinyl alcohol copolymers (EVOH), ethylene acrylic acid copolymers (EAA), PS, PC, PVC, styrene-butadiene-styrene (SBS), PA, etc., or mixtures thereof. Such polymers are characterized by high MW, which generally determines melt processability and solid-state mechanical properties. For the purposes of the present invention, the terms "polymer" and "plastic" are used interchangeably, and the term "MW" refers to the weight average molecular weight of the polymer.

[0034] As used herein, the term "recycled polymer" refers to a polymer that has been used for a previous purpose and then recovered for further processing.

[0035] As used herein, the term "post-consumer" refers to a source of material that is generated after the ultimate consumer uses the material in a consumer good or product.

[0036] As used herein, the term "post-consumer recycled" (PCR) refers to material that is generated after the material has been used by an ultimate consumer and has been placed in the waste stream.

[0037] As used herein, the term "post-industrial recycled" (PIR) refers to sources of material generated during the manufacture of a good or product or prior to its use by a consumer.

[0038] As used herein, the term "fluid solvent" refers to a substance that can exist in a liquid state under specific temperature and pressure conditions. In some embodiments, the fluid solvent can be the main uniform chemical composition of a molecule or isomer, and in other embodiments, the fluid solvent can be a mixture of several different molecular compositions or isomers. In addition, in some embodiments of the present invention, the term "fluid solvent" can also be applied to the critical temperature and critical pressure (critical point) of the material, the critical temperature and critical pressure (critical point) close to the material, or the material higher than the critical temperature and critical pressure (critical point) of the material. It is well known to those of ordinary skill in the art that the material higher than the critical point of the material is referred to as a "supercritical fluid", which does not have the typical physical properties (that is, density) of a liquid.

[0039] As used herein, the term "dissolved" means that a solute (polymer or non-polymer) is at least partially incorporated into a solvent at a molecular level. In addition, the thermodynamic stability of a solute / solvent solution can be described by the following equation: ΔG mix =ΔH mix -TΔS mix , where ΔG mix is the Gibbs free energy change of mixing of solute and solvent, ΔH mix is the enthalpy change of mixing, T is the absolute temperature, and ΔS mix is the entropy of mixing. In order to maintain a stable solution of a solute in a solvent, the Gibbs free energy must be negative and minimized. Therefore, any combination of solute and solvent that minimizes the negative Gibbs free energy at the appropriate temperature and pressure can be used in the present invention.

[0040] As used herein, the term "normal boiling point" refers to the boiling point temperature at an absolute pressure of exactly 100 kPa (1 bar, 14.5 psia, 0.9869 atm) as determined by the International Union of Pure and Applied Chemistry (IUPAC).

[0041] As used herein, the term "standard enthalpy change of vaporization" refers to the enthalpy change required to transform a specified amount of a substance from liquid to vapor at the standard boiling point of the substance.

[0042] As used herein, the term "polymer solution" refers to a solution of a polymer dissolved in a solvent. A polymer solution may contain undissolved matter (e.g., at least one suspended contaminant), and thus a polymer solution may also be a "slurry" of undissolved matter suspended in a solution of a polymer dissolved in a solvent.

[0043] As used herein, the terms "sedimentation" and "sedimentation" are used interchangeably and refer to the tendency of particles within a suspension to separate from a liquid in response to a force acting on the particles, usually gravity.

[0044] As used herein, the term "suspended contaminants" refers to unwanted or undesirable components present throughout the bulk of the media of a heterogeneous mixture.

[0045] As used herein, the term "dissolved contaminants" refers to unwanted or undesirable components that are at least partially incorporated into the solvent at a molecular level.

[0046] As used herein, the term "filtration" refers to separating at least one dissolved contaminant and / or suspended contaminant from a fluid by using mechanical and / or physical manipulations (e.g., passing the contaminated fluid through a filtration system). As used herein, the terms "filtration system" and "filter" are used interchangeably.

[0047] As used herein, when referring to a solution, the term "less suspended contaminants" refers to a subsequent state of a solution relative to a previous state (eg, prior to a contaminant removal step), wherein the previous solution had a relatively larger amount of suspended contaminants.

[0048] As used herein, when referring to a solution, the term "containing even fewer suspended contaminants" refers to a subsequent state of a solution relative to a previous state (eg, "containing fewer suspended contaminants"), where the previous solution had a relatively greater amount of suspended contaminants.

[0049] As used herein, the term "solid medium" refers to a substance that exists in a solid state under the conditions of use. The solid medium can be crystalline, semi-crystalline or amorphous. The solid medium can be granular and can be supplied in different shapes (i.e., spheres, cylinders, pellets, etc.). If the solid medium is granular, the particle size and particle size distribution of the solid medium can be defined by the mesh size used to classify the granular medium. Examples of standard mesh size names can be found in the American Society for Testing and Materials (ASTM) standard ASTM E11 "Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves". The solid medium can also be a nonwoven fiber mat or a woven textile.

[0050] As used herein, the term "purer polymer solution" refers to a polymer solution that has less of one or more contaminants relative to the same polymer solution prior to a purification step.

[0051] As used herein, the term "extraction" refers to the operation of transferring a solute species from a liquid phase (or solid matrix) across a phase boundary to a separate immiscible liquid phase. The driving force for extraction is described via partition theory.

[0052] As used herein, the term "extracted" refers to a material that has less of one or more solute species relative to the same material prior to the extraction step. As used herein, the term "extracted regenerated polymer" refers to a regenerated polymer that has less of one or more solute species relative to the same regenerated polymer prior to the extraction step.

[0053] As used herein, the term "virgin" means substantially free of contaminants, colorless, odorless, homogeneous, and similar in properties to virgin polymer.

[0054] As used herein, the term "primarily polypropylene copolymer" refers to a copolymer having greater than 70 mol% of propylene repeating units.

[0055] As used herein, the term "predominantly polyethylene copolymer" refers to a copolymer having greater than 70 mol% of ethylene repeating units.

[0056] As used herein, any reference to international units of pressure (eg, MPa) refers to gauge pressure.

[0057] As used herein, the term "axial flow direction" refers to fluid flowing parallel to the long axis of the filter media.

[0058] As used herein, the term "radial flow direction" refers to fluid flowing perpendicular to the long axis of the filter media.

[0059] As used herein, the term "candle filter" refers to a device that uses pressure to separate solids from liquids. A detailed description of candle filters and other solid-liquid separation equipment is provided in the following reference: Perry, Robert H and Don W. Green. Perry's Chemical Engineers' Handbook. New York: McGraw-Hill, 2008.

[0060] 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 and one or more layers of fine solid materials (e.g., diatomaceous earth, perlite, cellulose fibers, clay, activated carbon, alumina, silica, aluminum silicate, zeolites, and mixtures thereof) are deposited on the screen.

[0061] As used herein, the term "body feed" refers to the addition of filter aids to a fluid prior to filtering the fluid.

[0062] As used herein, the term "contaminant" refers to any undesirable material contained on the surface of a plastic or in the bulk of the plastic. The term "chemical contaminant" refers to any undesirable chemical on the surface of a plastic or in the bulk of a plastic, and includes the molecular or elemental composition of the contaminant. Depending on the intent, the terms may be used interchangeably. For example, a paper contaminant includes cellulose. Thus, cellulose is a chemical contaminant among paper contaminants.

[0063] As used herein, the term "pollution" refers to the sum of all pollutants, and the term "chemical pollution" refers to the sum of all chemical pollutants. Chemical pollutants are grouped into categories, which include chemical pollutants with similar chemical structures. For example, As, Hg, and Cr are chemical pollutants in the "heavy metals" classification. Each pollutant can have different chemical properties, such as solubility and diffusivity in plastics, and target levels depending on concentration and end-use market.

[0064] As used herein, the term "surface contaminant" refers to contaminants on the surface of a plastic. Similarly, the term "surface chemical contaminant" refers to the molecular or elemental composition of the surface contaminant. Surface contaminants may be loosely attached to the plastic surface by physical attraction, or more strongly attached to the plastic surface by polar or other forces. Typically, a surface contaminant will have less than about 80% of its surface area embedded in the plastic.

[0065] As used herein, the term "bulk contaminant" refers to the contaminant in the bulk of the plastic. Similarly, the term "bulk chemical contaminant" refers to the molecular or elemental composition of the bulk contaminant. Typically, a bulk contaminant will have more than about 80% of its surface area embedded in the plastic.

[0066] As used herein, the terms "surface contamination" and "surface chemical contamination" refer to the sum of all surface contaminants and all surface chemical contaminants, respectively.

[0067] As used herein, the terms "total pollution" and "total chemical pollution" refer to the sum of all total pollutants and all total chemical pollutants, respectively.

[0068] 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.

[0069] As used herein, the term "permeable contaminants" refers to chemical contaminants that are soluble and diffusible in plastics. Non-limiting examples of permeable contaminants are formaldehyde, bisphenol A, and naphthalene.

[0070] As used herein, the term "impermeable contaminants" refers to chemical contaminants that are not soluble or diffuse in plastics. Non-limiting examples of impermeable contaminants are heavy metals and gel particles composed of cross-linked or ultra-high MW plastics (too large to diffuse).

[0071] As used herein, the term "permeable contamination" refers to the sum of all permeable contaminants, and the term "impermeable contamination" refers to the sum of all impermeable contaminants. The sum of all permeable and impermeable contaminants is a "chemical contaminant" if described in molecular or elemental terms, or simply a "contaminant" if described in general terms (such as cellulose and paper).

[0072] As used herein, the term "intentional contaminant" refers to a contaminant that is intentionally added by the supply chain for a specific purpose to benefit the producer, retailer or consumer, but may not be desired in recycled plastics. Examples include printed matter, paper labels, adhesives for labels, pigments (such as TiO2), processing additives (such as antioxidant-AO), etc., which are necessary for marketing, branding, processability and / or end-use performance. As used herein, the term "intentional chemical contaminant" refers to an intentional contaminant described by its chemical composition. As used herein, the term "intentional contamination" refers to the sum of all intentional contaminants, and the term "intentional chemical contamination" refers to the sum of all intentional contaminants described by their chemical composition.

[0073] As used herein, the surface area to volume ratio of a plastic is calculated as follows. For generally spherical objects, such as pellets, ground pellets, micronized pellets, etc., the surface area to volume ratio is calculated by 3 / r, where r is the mass average radius. For generally flat and thin objects, such as films, the surface area to volume ratio is calculated by 2 / t, where t is the mass average thickness. For generally long columnar objects, such as fibers, the surface area to volume ratio is calculated by 2 / r, where r is the mass average radius. For the purposes of the present invention, the terms "mass average surface area to volume ratio" and "surface area to volume ratio" are used interchangeably.

[0074] 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 producer, retailer, or consumer. As used herein, the term "unintentional chemical contaminant" refers to an unintentional contaminant described by its chemical composition. As used herein, the term "unintentional contamination" refers to the sum of all unintentional contaminants, and the term "unintentional chemical contamination" refers to the sum of all unintentional contaminants described by their chemical composition.

[0075] As used herein, the term "densified" refers to a state of plastic where the bulk density of the plastic is higher than that of the original / pre-densified plastic and the original surface of the plastic is reduced and / or made inaccessible to wetting fluids. The process of producing a densified material is called densification.

[0076] As used herein, the term "melt densification" refers to densification near, at, or above the initial melting point of the plastic. Non-limiting methods of melt densification include melt extrusion and agglomeration using equipment such as the Herbold HV series plastic compactor.

[0077] As used herein, the term "initial melting point" refers to the peak melting point (highest endothermic peak on a zero slope baseline) of a plastic as measured using differential scanning calorimetry (DSC). For purposes of the present invention, the terms "initial melting point," "melting point," "melting temperature," and "initial melting temperature" are used interchangeably. For amorphous materials and / or materials that lack a distinct melting point, the limiting temperature will be the approximate softening point of the material, which may be best characterized by the glass transition temperature. Those skilled in the art will understand the appropriateness of the criteria for non-semi-crystalline materials.

[0078] As used herein, the term "hexane" refers to a blend of hexane isomers, such as n-hexane (at least 45 vol %, and typically about 53 vol %), isohexane (2-methylpentane, 3-methylpentane, and 2,3-dimethylbutane), and neohexane (2,2-dimethylbutane).

[0079] As used herein, the term "limit of quantitation" or "LOQ" refers to the lower limit of detection of a given chemical contaminant as determined by the analytical method disclosed in Section IX. The LOQ is a function of the method used and can vary depending on the test method. The LOQ used herein is specific to the method listed in Section IX.

[0080] As used herein, the term "removal efficiency" refers to the efficiency of the process of removing a specific pollutant, calculated as 100×(initial concentration-final concentration) / initial concentration and expressed as a percentage. In the case where the final concentration is below LOQ and for simplicity, the removal efficiency is considered to be 100%. In some cases, due to: 1) measurement errors, 2) pollutant hot spots and cold spots in recycled polymers, and 3) external contamination during sampling, purer plastics will have higher levels of pollutants than recycled polymers. In this case, the removal efficiency is set to 0% so as not to deviate from the average result. If this happens consistently in a given process, this is more likely to be attributed to the process and should be checked more carefully, but this is not usually the case with the process of the present invention. As used herein, the term "average removal efficiency" refers to the average value of the removal efficiency of each pollutant.

[0081] For the purposes of the present invention, the terms "purification process" and "dissolution recycling process" are used interchangeably. In addition, for the purposes of the present invention, the terms "step" and "process step" are used interchangeably.

[0082] As used herein, the word “or” when used as a conjunction of two or more elements is meant to include the elements individually or in combination; for example, X or Y means X or Y or both.

[0083] As used herein, the articles "a" and "an" are understood to mean one or more of the material claimed or described.

[0084] II. Recycled polymers

[0085] When first produced at resin suppliers such as Dow, Nova, ExxonMobil, etc., polymers are largely free of contamination (virgin plastic). However, during the polymer's life cycle (from production to distribution, consumer use, and eventual recycling), contamination is introduced intentionally or unintentionally.

[0086] Non-limiting examples of intentional contamination include surface printing, paper labels, adhesives for labels, pigments (such as TiO2), processing additives (such as AO), etc., which are necessary for market, brand, processability and / or end-use performance. Non-limiting examples of unintentional contamination are dirt, cross contamination, certain heavy metals, pesticides, dioxins, furans, PCBs, etc. In addition, unintentional contamination can be produced by reactions involving intentional pollutants, such as oxidation of paper labels to dioxins, degradation of adhesives or printing binders, etc. Most of the latter occur during the melt densification method used in the recycling process. In addition, during the melt processing step (such as those steps for original packaging or product manufacturing and / or the latter recycling), the oxidation of plastics will produce unintentional contamination, such as gel. In addition, unintentional contamination may be caused by interaction with the product. For example, packaging materials containing cleaning mixtures (for example, limonene, surfactants, etc.), food (for example, various organics), etc. will potentially be contaminated by such products. Finally, unintentional contamination can enter plastics during production, such as contaminating plastics with reaction byproducts, unreacted monomers, etc.

[0087] It should be recognized that different recycled polymer sources have different pollution and related risks. Obviously, recycled polymer streams of unknown origin and life cycle will be the most abundant, but also represent the highest possibility of pollution. On the other hand, controlled recycled polymer streams are available and show lower potential risks for demanding applications. For example, if it is known that the recycled polymer stream comes from a demanding application, such recycled polymer streams will not contain any undesirable contaminants until they are distributed to consumers, otherwise these plastics will not be approved for these applications. Therefore, the pollution that prevents reuse in these same applications is mainly unintentional pollution, which must originate from external sources and enter the plastic through surface contamination. Small amounts of pollution may be caused by reactions involving intentional pollution, such as oxidation of cellulosic materials to dioxins during melt densification.

[0088] Pre-consumer plastics generally have the lowest contamination levels due to their known composition and controlled history. It can include intentional contamination, such as surface printing and opacifiers, but because these are known and controlled, it is very easy to find applications that tolerate such known contaminants. In addition, due to the controlled history, pre-consumer plastics tend to have a small amount of unintentional contamination, thereby preventing external contamination. Therefore, pre-consumer plastics originally intended for demanding applications would be an ideal source of recycled polymers for the same end market with minimal cleaning / purification. The latter pre-consumer plastic in film form is called "approved source post-industrial film" (ASPIF). On the downside, ASPIF streams are in very limited supply and do not support roundness.

[0089] Post-consumer plastics are generally more contaminated than pre-consumer plastics. Considering the slightly controlled life cycle in the commercial supply chain, the commercial post-consumer sub-category of post-consumer plastics has the second lowest contamination level relative to pre-consumer recycling. Typically, commercial post-recycled plastics will have known and controlled levels of intentional contamination, so they can be widely used as recycled polymers. However, it is known that unintentional contamination is ubiquitous, and there are problems with this stream, which hinders widespread use in demanding applications. Commercial post-plastics derived from demanding applications will likely be returned to these fields after sufficient cleaning / purification. Commercial post-plastics derived from demanding applications in the form of films are referred to as "approved source commercial post-film" (ASPCF). In order to adapt to the continued demand for purer recycled polymers, recycling material suppliers have recently introduced commercial post-film sources with more controlled and known histories. These new sources are called high-custody sources and are mainly used with commercial post-film streams. Therefore, high-custody commercial post-film sources should have reduced contamination levels relative to general commercial post-film sources. On the downside, these high-custody sources are limited in volume and costly.

[0090] The post-consumer, post-home subcategory has the highest level of contamination given the uncontrolled lifecycle within the commercial channel. This category of plastic has high levels of intentional and unintentional contamination that are highly variable, unknown, and uncontrolled. This category of plastic may include sources of plastic that were not originally intended for use in demanding applications. Therefore, the market for this source of plastic is limited and is essentially nonexistent in demanding applications.

[0091] Surprisingly, the purer plastics made by the present invention may allow for wider use of plastics from post-industrial sources (ASPIF and uncontrolled sources), post-commercial sources (ASPCF and uncontrolled sources), and post-domestic sources for demanding applications with some limitations. Furthermore, most consumers of recycled materials require purer materials than are currently available, and the purer plastics of the present invention meet this broader need for purer plastics from any source.

[0092] For purposes of the present invention, non-limiting examples of polymers are films, sheets, injection molded parts, blow molded parts, fibers, nonwovens, wovens, thermoformed parts, and extruded strands.

[0093] The recycled polymer may be a first life plastic (used only once before it enters the recycled polymer stream), a second life plastic (used twice before it enters the recycled polymer stream), or a higher life plastic (used multiple times before it enters the recycled polymer stream). In an embodiment of the present invention, the recycled polymer comprises a virgin plastic. In an embodiment of the present invention, the recycled polymer comprises a film. In an embodiment of the present invention, the recycled polymer is selected from the group consisting of a film, an injection molded part, a blow molded part, a fiber, a nonwoven, a woven, a thermoformed part, an extruded strand, or a mixture thereof.

[0094] In an embodiment of the present invention, the recycled polymer comprises regrind / offcut / in-plant waste plastic. In an embodiment of the present invention, the recycled polymer comprises PIR polymer. In an embodiment of the present invention, the recycled polymer comprises PIR polymer film. In an embodiment of the present invention, the recycled polymer comprises PIR polymer nonwoven. In an embodiment of the present invention, the PIR polymer film is ASPIF. In an embodiment of the present invention, the recycled polymer comprises PCR polymer. In an embodiment of the present invention, the recycled polymer comprises PCR polymer film. In an embodiment of the present invention, the recycled polymer comprises PCR polymer nonwoven. In an embodiment of the present invention, the PCR polymer film is ASPCF. In an embodiment of the present invention, the recycled polymer comprises high-care PCR polymer film. In an embodiment of the present invention, the recycled polymer comprises post-domestic polymer. In an embodiment of the present invention, the recycled polymer comprises post-domestic polymer film. In an embodiment of the present invention, the recycled polymer comprises post-domestic polymer nonwoven.

[0095] In an embodiment of the present invention, the recycled polymer comprises PS, copolystyrene, PA, copolyamide, PC, thermoplastic elastomer, styrene block copolymer, polyester, copolyester, PVC and copolymers of any of the above and mixtures of any of the above. In an embodiment of the present invention, the recycled polymer comprises polyolefin, polyolefin copolymer and polyolefin polar copolymer. In an embodiment of the present invention, the recycled polymer comprises LDPE and LLDPE copolymer. In an embodiment of the present invention, the recycled polymer comprises PP. In an embodiment of the present invention, the recycled polymer comprises HDPE and HDPE copolymer. In an embodiment of the present invention, the recycled polymer comprises a film, and the film comprises polyethylene and polyethylene copolymer.

[0096] In an embodiment of the present invention, the regenerated polymer is a PCR polymer. In an embodiment of the present invention, the regenerated polymer is a polypropylene homopolymer or a primarily polypropylene copolymer. In an embodiment of the present invention, the regenerated polymer is a polyethylene homopolymer or a primarily polyethylene copolymer. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises obtaining the regenerated polymer; and wherein the regenerated polymer is selected from the group consisting of a PCR polymer, a PIR polymer, and the like. The regenerated polymer can be in many forms, including but not limited to pellets, micronized pellets, ground pellets, chopped films, chopped or ground injection molded parts, chopped or ground blow molded parts, thermoformed parts, chopped nonwovens or wovens, extruded strands, or agglomerated particles. In an embodiment of the present invention, the regenerated polymer comprises pellets.

[0097] In an embodiment of the present invention, the recycled polymer has a thickness greater than about 1 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of greater than about 5 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of greater than about 20 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio of greater than about 50 mm -1 The average surface area to volume ratio.

[0098] For purposes of the present invention, recycled polymers are derived from post-consumer, post-industrial, post-commercial, and / or other special recycled waste streams. For example, PCR polymers may be obtained from a curbside recycling stream, where the end consumer places used polymers from packaging and products into a designated trash bin for collection by a garbage truck or recycler. PCR polymers may also be derived from an in-store "take-back" program, where the consumer brings waste polymers into the store and places the waste polymers into a designated collection bin. An example of a PIR polymer may be waste polymers generated during the manufacture or transportation of goods or products that are collected by the manufacturer as unusable materials (i.e., trimming waste, out-of-spec materials, startup waste). An example of a waste polymer from a special waste stream may be waste polymers obtained from the recycling of electronic waste (also referred to as "e-waste"). Another example of a waste polymer from a special waste stream may be waste polymers obtained from the recycling of automobiles. Another example of a waste polymer from a special waste stream may be waste polymers obtained from the recycling of used carpets and textiles.

[0099] For the purposes of the present invention, a recycled polymer is a homogeneous composition of a single polymer or a mixture of several different polymer compositions. Non-limiting examples of recycled polymer compositions are homopolymers and copolymers of polyolefins such as polyethylene and isotactic polypropylene; polyesters such as polyethylene terephthalate; vinyl polymers such as polyvinyl chloride; styrene polymers such as polystyrene; polyamides such as poly(hexamethylene adipamide); polycarbonates such as poly(bisphenol A carbonate); polyacrylates such as poly(methyl methacrylate); polysiloxanes such as polydimethylsiloxane; thermoplastic elastomers such as styrene-butadiene block copolymers and ethylene-propylene rubber; and other soluble polymers that may be apparent to one of ordinary skill in the art.

[0100] Recycled polymers may also contain various pigments, dyes, processing aids, stabilizing additives, fillers and other performance additives, which are added to the polymer during the polymerization of the original polymer or conversion into the final form of the product. Non-limiting examples of pigments are organic pigments such as copper phthalocyanine, inorganic pigments such as titanium dioxide and other pigments that may be obvious to those of ordinary skill in the art. A non-limiting example of an organic dye is Basic Yellow 51. Non-limiting examples of processing aids are antistatic agents such as glyceryl monostearate and slip agents such as erucamide. Non-limiting examples of stabilizing additives are octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate. Non-limiting examples of fillers are calcium carbonate, talc and glass fiber.

[0101] III. Pollutants

[0102] Pollutants can generally be broken down into two migration categories: 1) permeable; and 2) impermeable. Permeable pollutants have solubility and diffusivity in the regenerated polymer to allow migration into, through, and out of the polymer due to the chemical potential gradient. In other words, permeable pollutants and groups called permeable pollution are removable. Impermeable means that the pollutant does not have enough solubility and diffusivity to significantly move into, through, and out of the polymer. In other words, the impermeable pollution represented by the sum of all impermeable pollutants is essentially fixed. Therefore, no matter where the impermeable pollutant is first deposited, such pollution will remain in the position until physically removed, convectively transferred, or placed in contact with different materials that are permeable to the pollutant.

[0103] Chemical contaminants in recycled polymers can be multiple, but typically belong to one of several related chemical classes. Non-limiting examples of related chemical classes are pesticides, aldehydes, allergic fragrances, indolines, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, organotin, metals, phthalates, and polycyclic aromatic hydrocarbons (PAHs). Only some of these chemical classes, such as pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, metals, organotin, phthalates, and PAHs, are routinely found in pre- and post-consumer recycled polymers.

[0104] Using the analytical methods disclosed in Section IX, the LOQs for various contaminants can vary by several orders of magnitude. For example, the LOQ for a typical pesticide is about 10 ppb; the LOQ for a typical alkylphenol ethoxylate is about 50 ppb; the LOQ for a typical alkylphenol is about 5 ppb; the LOQ for bisphenol A is about 5 ppb; the LOQ for a typical dioxin is about 0.2 ppt; the LOQ for a typical furan is about 0.2 ppt; the LOQ for a typical PCB is about 5 ppt; the LOQ for a typical heavy metal is about 100 ppb; the LOQ for a typical organotin is about 300 ppt; the LOQ for a typical phthalate is 50 ppb; and the LOQ for a typical PAH is 1 ppb.

[0105] As shown in Tables 1a-1i, several membrane sources were broadly classified for chemical contamination using the analytical methods disclosed in Section IX, including three ASPIF sources, three high-security commercial post-membrane sources, three commercial post-membrane sources, and one domestic post-membrane source. To simplify the presentation of chemical contamination results, concentration data are shown as LOQ rather than absolute weight fraction. For example, if the contaminant concentration is 10 ppm and the LOQ is 1 ppm, the concentration will be 10×LOQ or simply 10 in the data table. In addition, "dnt" stands for "not tested."

[0106] Table 1a-1i

[0107] Chemical contamination from ASPIF, High Custody Commercial Post-Use (HCPC), Commercial Post-Use (PC), and Domestic Post-Use (PH) membrane sources

[0108] Table 1a

[0109] Chemical pollution - pesticides

[0110]

[0111] Table 1b

[0112] Chemical pollution - Alkylphenol ethoxylates

[0113]

[0114]

[0115] Table 1c

[0116] Chemical pollution-Alkylphenol

[0117]

[0118] Table 1d

[0119] Chemical pollution-bisphenol

[0120]

[0121] Table 1e

[0122] Chemical pollution - dioxins, dioxin-like compounds, furans and PCBs

[0123]

[0124] Table 1f Chemical pollution - metals

[0125]

[0126]

[0127] Table 1g Chemical pollution-organic tin

[0128]

[0129] Table 1h Chemical contamination - phthalates

[0130]

[0131]

[0132] Table 1i

[0133] Chemical pollution-PAH

[0134]

[0135] The ASPIF sources tested were largely free of detectable levels of chemical contaminants, except for alkylphenols and heavy metals and small amounts of organotins and PAHs. The chemical contamination results for these ASPIF sources are used as a guide to the chemical contamination levels that represent these controlled end markets, and demonstrate that heavy metals with low transfer risks are ubiquitous in all membrane sources anyway. Therefore, heavy metals are not included in the ongoing analysis within this application. The high-custody commercial post-membrane sources tested were largely free of pesticides and alkylphenol ethoxylates, but contained detectable levels of alkylphenols, bisphenol A, dioxins / furans / PCBs and PAHs and low levels of phthalates. The commercial post-membrane sources tested were severely contaminated by each category evaluated; for example, dioxins were generally up to 40×LOQ, but for one source, dioxins were up to 200×LOQ. The tested household post-sources were the most contaminated; for example, dioxins were up to 300×LOQ, and PCBs were up to 180×LOQ.

[0136] From Tables 1a-1i, representative chemicals were selected from various categories based on their prevalence in the spectrum of recycled polymer sources. The chemicals selected within these categories are: piperonyl butoxide (indicating pesticides); 4-tert-octylphenol hexaethoxylate and isononylphenol triethoxylate (indicating alkylphenol ethoxylates); isononylphenol and 4-tert-amylphenol (indicating alkylphenols); bisphenol A (indicating phenols); 1.2.3.6.7.8-HxCDD, 1.2.3.4.6.7.8-HpCDD, and OCDD (indicating dioxins); OCDF (indicating furans); PCB 105 and PCB 118 (indicating PCBs); monobutyltin and dibutyltin (indicating organotins); dibutylphthalate and di-2-ethylhexylphthalate (indicating phthalates); fluoranthene and phenanthrene (indicating PAHs) (Table 2).

[0137] In an embodiment of the present invention, the chemical contaminants in the recycled polymer include at least one chemical contaminant, and the chemical contaminant is selected from the group consisting of pesticides, alkylphenols, alkylphenol ethoxylates, bisphenols, dioxins, furans, PCBs, phthalates, PAHs or mixtures thereof.

[0138] In an embodiment of the present invention, the pesticides include piperonyl butoxide, benzalkonium chloride (BAC), N,N-diethyl-m-toluamide (DEET) and didecyldimethylammonium chloride (DDAC). In an embodiment of the present invention, the alkylphenol ethoxylates include isononylphenol monoethoxylate, isononylphenol diethoxylate, isononylphenol triethoxylate and isononylphenol tetraethoxylate. In an embodiment of the present invention, the alkylphenols include isononylphenol, 4-tert-butylphenol and 4-tert-amylphenol. In an embodiment of the present invention, the bisphenols include bisphenol A. In an embodiment of the present invention, the dioxins include 1,2,3,6,7,8-HxCDD, 1.2.3.4.6.7.8-HpCDD and OCDD. In an embodiment of the present invention, the furans include OCDF. In an embodiment of the present invention, the PCB includes PCB 77, PCB 81, PCB 126, PCB 105, PCB 114, PCB 118, PCB 123, PCB 156 and PCB 167. In an embodiment of the present invention, 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 PAH includes acenaphthene, acenaphthene, anthracene, benzo[a]anthracene, benzo[b]fluoroanthracene, benzo[e]pyrene, benzo[ghi]perylene, Cyclopenta[cd]pyrene, fluoranthene, fluorene, naphthalene, phenanthrene and pyrene. In an embodiment of the present invention, the organotin includes monobutyltin, dibutyltin and dioctyltin.

[0139] In embodiments of the present invention, the contaminants in the regenerated polymer may include 4-tert-amylphenol. In embodiments of the present invention, the contaminants in the regenerated polymer may include bisphenol A. In embodiments of the present invention, the contaminants in the regenerated polymer may include OCDD. In embodiments of the present invention, the contaminants in the regenerated polymer may include PCB 118. In embodiments of the present invention, the contaminants in the regenerated polymer may include di-2-ethylhexyl phthalate.

[0140] In order to simplify the presentation of the purification results of the present invention and the related examples, the number of chemicals presented per chemical category is limited to the above representative chemicals of each chemical category as shown in Table 2, as well as the corresponding levels of the relevant LOQ and ASPIF sources tested. Although more in-depth and complete chemical analysis was completed for all the objects of the present invention, only selected chemicals are continuously shown. This simplification does not affect or change the present invention or the conclusions drawn therefrom. The selected chemicals fully and consistently represent the broader categories regarding purification.

[0141] Table 2

[0142] Selected chemical contaminants and associated LOQ concentrations

[0143]

[0144]

[0145] In an embodiment of the invention, the concentration of each pesticide in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable pesticide. In an embodiment of the invention, the concentration of bisphenol A in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least detectable bisphenol A. In an embodiment of the invention, the concentration of each dioxin in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable dioxin. In an embodiment of the invention, the concentration of each PCB in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable PCB. In an embodiment of the invention, the concentration of each phthalate in the purer plastic is below its corresponding LOQ; wherein the recycled polymer has at least one detectable phthalate.

[0146] In an embodiment of the present invention, the concentration of piperonyl butoxide in the purer plastic is less than about 10 ppb; wherein the concentration of piperonyl butoxide in the recycled polymer is higher than 10 ppb; the concentration of 4-tert-amylphenol in the purer plastic is less than about 5 ppb; wherein the concentration of 4-tert-amylphenol in the recycled polymer is higher than 5 ppb; the concentration of bisphenol A in the purer plastic is less than about 5 ppb; wherein the concentration of bisphenol A in the recycled polymer is higher than 5 ppb; the concentration of OCDD in the purer plastic is less than about 0.2 ppt; wherein the concentration of OCDD in the recycled polymer is higher than 0.2 ppt; the concentration of PCB 118 in the purer plastic is less than about 10 ppt; wherein the concentration of PCB 118 in the recycled polymer is higher than 10 ppt; the concentration of di-2-ethylhexyl phthalate in the purer plastic is less than about 50 ppb; wherein the concentration of di-2-ethylhexyl phthalate in the recycled polymer is higher than 50 ppb.

[0147] In an embodiment of the invention, the removal efficiency of piperonyl butoxide contaminants is greater than 55%; and the concentration of piperonyl butoxide in the recycled polymer is at least 10 ppb. In an embodiment of the invention, the removal efficiency of piperonyl butoxide contaminants is greater than 85%. and the concentration of piperonyl butoxide in the recycled polymer is greater than about 10 ppb.

[0148] In an embodiment of the invention, the removal efficiency of 4-tert-amylphenol contaminants is greater than 55%, wherein the concentration of 4-tert-amylphenol in the regenerated polymer is at least 5 ppb. In an embodiment of the invention, the removal efficiency of 4-tert-amylphenol contaminants is greater than 85%, wherein the concentration of 4-tert-amylphenol in the regenerated polymer is at least 5 ppb.

[0149] In an embodiment of the present invention, the removal efficiency of bisphenol A contaminants is greater than 55%, and the concentration of bisphenol A in the recycled polymer is at least 5 ppb. In an embodiment of the present invention, the removal efficiency of bisphenol A contaminants is greater than 79%, and the concentration of bisphenol A in the recycled polymer is greater than about 5 ppb.

[0150] In an embodiment of the present invention, the removal efficiency of OCDD contaminants is greater than 55%, and the concentration of OCDD in the recycled polymer is greater than about 0.2 ppt. In an embodiment of the present invention, the removal efficiency of OCDD contaminants is greater than 95%, and the concentration of OCDD in the recycled polymer is greater than about 0.2 ppt.

[0151] In an embodiment of the present invention, the removal efficiency of OCDF contaminants is greater than 55%, and the concentration of OCDF in the recycled polymer is greater than about 0.2 ppt. In an embodiment of the present invention, the removal efficiency of OCDF contaminants is greater than 93%, and the concentration of OCDF in the recycled polymer is greater than about 0.2 ppt.

[0152] In an embodiment of the present invention, the removal efficiency of PCB 118 contaminants is greater than 55%, and the concentration of PCB 118 in the recycled polymer is at least 10 ppt. In an embodiment of the present invention, the removal efficiency of PCB 118 contaminants is greater than 66%, and the concentration of PCB 118 in the recycled polymer is greater than about 10 ppt.

[0153] In an embodiment of the present invention, the removal efficiency of di-2-ethylhexyl phthalate contaminant is greater than 55%, and the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb. In an embodiment of the present invention, the removal efficiency of di-2-ethylhexyl phthalate contaminant is greater than 78%, and the concentration of di-2-ethylhexyl phthalate in the recycled polymer is greater than about 50 ppb.

[0154] In an embodiment of the present invention, the removal efficiency of phenanthrene contaminants is greater than 55%, and the concentration of phenanthrene in the regenerated polymer is at least 1 ppb. In an embodiment of the present invention, the removal efficiency of phenanthrene contaminants is greater than 93%, and the concentration of phenanthrene in the regenerated polymer is at least 1 ppb.

[0155] Pollution can be located on the surface of plastics or in the whole. Through the surface cleaning technology available on the market, the pollution on the surface is most conveniently and easily removed. If the surface pollution in the plastic is permeable, it will become the whole pollution through the diffusion mechanism over time, thus complicating the reduction and limiting the effectiveness of the surface cleaning technology. If the surface pollution is impermeable in the plastic, such pollution will not spread into the whole and will be reduced by simple surface cleaning methods such as aqueous washing. The whole pollution of permeable or impermeable types cannot be effectively removed by simple surface purification methods such as aqueous washing. The whole pollution of impermeable types (also referred to as whole impermeable pollution) is trapped in the whole plastic and can be released by the mechanism including melt convection, melt filtration or dissolution / decomposition of the whole plastic.

[0156] As previously discussed, contamination can be introduced from the outside throughout the life cycle of the plastic. If the contamination is impermeable, such contamination will remain largely on the surface until recycling during the life cycle of the plastic. If the contamination is permeable, the contamination will migrate into the bulk plastic over time. Therefore, in the absence of contamination or purification events, the contamination will remain essentially constant, but the balance of surface and bulk contamination will change over time, but will approach equilibrium over a long period of time. Typically, loosely bound surface contamination such as dirt can be 0.01% by weight to about 0.1% by weight; while chemical contamination, especially chemical contaminants to which the present invention relates, will be at ppm, ppb or even ppt levels.

[0157] Permeable and impermeable contamination represent different challenges in demanding applications. For example, permeable contamination, whether in the overall plastic or on the surface of the plastic, will have the potential to migrate to uncontaminated materials such as products or human skin. Therefore, if the packaging contains permeable contaminants, such contaminants will have the potential to migrate into the product and make it unsuitable for these demanding end markets. However, if the contaminant is impermeable and in the overall plastic, it will have a low ability to transfer to the product or the user's skin unless the overall plastic is decomposed or ingested. Therefore, packaging can potentially use such contaminated plastic materials, and there is no risk of contamination transfer to the product or directly to the skin. However, if the contaminant is impermeable and on the surface of the plastic, such contaminants will have the ability to transfer to the product or skin by direct contact transfer, and will be unacceptable for use in these demanding applications. Permeable and impermeable surface contamination can be converted into overall contamination by convection mechanisms (such as melt mixing and melt densification). These methods exchange or eliminate surface areas with the overall material. For example, if the film melt of surface contamination is densified or melt extruded into different shapes, such as pellets, all original surface contamination will become overall contamination, whether it is impermeable or not, and such overall contamination will be more difficult to remove with purification methods. Melt densification is common in the recycling industry. It is also common to crush incoming plastics in the recycling industry. The latter method does not convert surface contamination into overall contamination usually. Ideally, surface purification methods such as surface washing occur on the original contaminated surface such as shredded film, wherein all original surface areas are accessible by surface washing fluids.

[0158] Generally, it is difficult to distinguish surface contamination and overall contamination using analytical methods. Most analytical methods for permeable chemical contaminants relate to solvent extraction of pollutants from plastics in an extended period greater than 6h and exposed to an extreme solvent greater than 100:1 and a plastic mass ratio, and then use methods such as gas chromatography-mass spectrometry (GC-MS) to quantify the pollutants in the solvent. Such analytical methods quantify pollution, but will not distinguish between surface and overall pollutants. The efficiency of the purification method for removing surface contamination can be estimated according to the difference of the pollution before and after the surface cleaning step, but it is assumed that overall pollution is not significantly affected, which may be the case of surface washing with the aqueous surface washing fluid discussed in the present invention. The more accurate way of quantitative surface contamination is by washing, then at different times to the pollutant solvent extraction, and then extrapolating the amount of the pollutant removed in infinitesimal time, which will approximate the amount of surface contamination. However, the method is time-consuming and costly, particularly for pollutants that are usually difficult to measure. In addition, since the balance of surface and overall pollutants is dynamic, it is difficult to quantify without reference to the precise sampling time. A simple method for quantifying general surface contamination (not chemical surface contamination or substance-based chemical contamination) is to weigh the regenerated polymer before and after the surface washing step.

[0159] Typically, bulk contamination will not be significantly removed by simple aqueous surface washing. Permeable bulk contamination can be removed by diffusion mechanisms via chemical potential gradients. While bulk impermeable contamination is essentially trapped by the bulk polymer, methods for releasing the trapped contaminant include melt convection, melt filtration, and dissolution / disintegration of the plastic.

[0160] 1. In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates. In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof;

[0161] and wherein the recycled polymer contains pollutants, each of which has a certain concentration; and wherein the recycled polymer pollutants include 4-tert-amylphenol, bisphenol A,

[0162] At least one of OCDD, PCB 118 and 2-ethylhexyl phthalate. In an embodiment of the present invention, the alkylphenol, bisphenol, dioxin, PCB and phthalate include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate.

[0163] IV. Surface Purification Process

[0164] Surface purification reduces surface contamination. A kind of such method is to carry out surface washing with a surface washing fluid that is usually water-based. Surface washing is ideally completed before any melt mixing or melt densification to allow effective cleaning of the original contaminated surface. Regenerated polymers are generally in the form of pellets, loose or compacted films, loose or compacted flexible packaging, loose or compacted rigid materials, loose or compacted nonwovens, etc., which are difficult to carry out surface washing due to their excessive overall size. Therefore, before surface washing, preferably granulation or chopping steps. For film, it is particularly important to peel off all available film layers so that washing fluids can approach all original surface contaminations. Therefore, the size reduction step before surface washing should not significantly reduce the average surface area and volume ratio of the regeneration source, or exchange with a new surface area.

[0165] In an embodiment of the invention, the surface washing of the regenerated polymer is performed after the chopping or granulation step. The surface washing will include significant mechanical agitation to loosen surface dirt and other contaminants, thereby allowing physical removal and transfer to the washing fluid, where the dirt or other contaminants may or may not be dissolved.

[0166] As used herein, in the surface washing step, the recycled plastic in its original contamination form (except that the possibility of volumetric size reduction exceeding 25% of the original surface is not eliminated) is contacted with an aqueous solution under mechanical agitation and then separated from the aqueous medium now containing such contamination. Such a surface washing step will generally remove most of the loosely bound surface contamination, including but not limited to dirt, wood, loosely bound paper and some surface chemical contamination. The typical level of loosely bound surface contamination based on the regeneration source of the membrane is between about 0.01% and 0.1% by weight. In an embodiment of the present invention, surface washing will remove more than about 80% of the loosely bound surface contamination.

[0167] Surface washing technologies are widely available in the market. One technology comes from Lindner (Lindner Washtech GmbH, 4, Germany). This technology is described in detail elsewhere (https: / / www.lindner-washtech.com / system-solutions), but involves water washing under vigorous mechanical agitation and the possibility of applying caustic to remove binders, followed by drying and granulation. Another technology comes from Herbold (Herbold Meckesheim USA, North Smithfield, RI). This technology is described in detail elsewhere (https: / / www.herbold.com / en / machines / washing-separating-drying-2 / ) and also involves various water washing steps under vigorous mechanical agitation, followed by drying and granulation. Another technology comes from Sorema (Sorema Srl, Anzano del Parco, Italy). This technology is described in detail elsewhere (http: / / sorema.it / en_US / applications / washing-line / ) but involves similar aqueous operations relative to Lindner and Herbold. Finally, another technology comes from Cadel, called deinking (Cadel Deinking, Alicante, Spain). This technique is described elsewhere (http: / / cadeldeinking.com / en / ), but essentially involves surface washing of the material using a high temperature water-based solution with a specific surfactant, followed by a water rinse and drying. The process may optionally include densification, melt filtration, devolatilization and granulation after the surface washing. This method differs from other known methods in that it requires the removal of surface printing inks. This will be advantageous due to the reduced burden of removing chemical contaminants by the overall purification method of the present invention.

[0168] Three surface washing technologies of the prior art were evaluated for the average removal efficiency of five selected pollutants (Comparative Examples 1, 2 and 3). Different regeneration membranes with different contamination levels were used to evaluate each surface washing technology. In general, the surface washing technology of the prior art cannot fully purify the regenerated polymer for use in controlled terminal markets. For the selected pollutants, although the initial contamination of the corresponding regenerated polymer is low, the commercial technology cannot be reduced to a level close to LOQ. In addition, the average removal efficiency of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and di-2-ethylhexyl phthalate is less than about 55%.

[0169] In an embodiment of the present invention, prior to the leaching step, the regenerated polymer is surface washed in a surface washing step in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination by greater than about 80%. In an embodiment of the present invention, prior to the leaching step, the regenerated polymer is surface washed in a surface washing step in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination by greater than about 80%; wherein the regenerated polymer has a thickness greater than about 1 mm before surface washing. -1 wherein the surface washing process is of the de-inking type; and wherein the de-inking process results in a ΔE change of less than about 10% between the de-inked polymer and the regenerated polymer without surface printing ink.

[0170] V. Melt Densification Process

[0171] Assuming the surface purification temperature is below the initial melting point of the recycled polymer, the plastic emerging from the surface purification step will generally have similar geometry and similar average surface area to volume ratio as the incoming recycled polymer. For example, if the recycled plastic is a loose film, the film will exit the surface purification as a shredded film after shredding and surface washing at a temperature below the initial melting point of the recycled polymer. Because such loose plastics are difficult to feed into certain bulk purification processes such as liquid-liquid extraction, it may be desirable to densify such plastic melts prior to bulk purification.

[0172] The preferred method of melt densification is melt extrusion. Melt extrusion not only densifies the plastic, but it can also provide the pressure required for downstream overall purification such as liquid-liquid extraction. Melt extrusion can also include optional steps such as melt filtration and / or devolatilization to remove bulk contaminants and / or volatile bulk contaminants. In addition, the melt-densified plastic can be further pressurized using a melt pump. A melt pump may be required to increase the pressure required for the downstream overall purification step. Other densification methods are known in the art, including rotating disk and rotating drum densifiers, which are performed at lower temperatures relative to melt-based methods.

[0173] In an embodiment of the invention, the melt densification comprises melt extrusion. In an embodiment of the invention, the melt extrusion comprises melt filtration. In an embodiment of the invention, the melt extrusion comprises melt devolatilization. In an embodiment of the invention, the melt extrusion comprises melt pumping. In an embodiment of the invention, the melt densification comprises melt extrusion, melt filtration, melt devolatilization and melt pumping.

[0174] VI. Immersion Leaching Process

[0175] Unexpectedly, it has been found that the submerged leaching step (disclosed in this section VI) or the combined step of surface purification and submerged leaching (disclosed in section VII) in combination with the purification process (disclosed in section VIII) produces a purer polymer from the regenerated polymer with much higher efficiency than when the purification process is used alone. Although not wishing to be bound by any theory, applicants hypothesize that removing contaminants in the leaching step makes it more efficient to remove the remaining contaminants in the various steps of the purification process than when there is no leaching step or surface purification and leaching step. Although not wishing to be bound by any theory, applicants believe that in the absence of a leaching step or surface purification and leaching step, the surface contaminants of the regenerated polymer become bulk contaminants, and therefore they become difficult to remove in the various steps of the purification process.

[0176] In general, bulk contamination will not be significantly reduced by simple aqueous surface washing. Melt filtration and melt devolatilization will have the potential to remove large geometric bulk contaminants and remove some volatile bulk contaminants, but will be largely ineffective for most bulk contaminants, especially at the levels required.

[0177] One commercial technology used for bulk purification is the InterRema Refresher from EREMA TM (EREMA Group, Ansfelden, Austria; https: / / www.erema.com / en / refresher / ). This technology is described in detail elsewhere, but essentially involves devolatilizing the particulate material to remove volatile organics at a temperature below the initial melting point of the plastic for an extended period of time. Most of the chemical contaminants associated with recycled polymers and discussed in the previous section are highly non-volatile, with normal boiling points typically above 200°C. Therefore, this type of devolatilization technology will have limited ability to remove most of the chemical contaminants mentioned in this application.

[0178] Other technologies based on devolatilization are common. These can be independent unit operations, or combined with other operations including extrusion and melt filtration. It is common to utilize those below ambient pressure above the molten stream of recycled plastics. An overall purification technology involving devolatilization has been analyzed for its purification capacity. The technology involves a slightly elevated temperature but below the initial melting point of the plastic, a long residence time (greater than about 2h) and continuous reflux of purified air to provide devolatilization (Comparative Example 4). Commercial devolatilization technology cannot fully remove the selected pollutants. For example, the selected pollutants are still well above LOQ, and the average removal efficiency is about 41%.

[0179] Extraction is the preferred overall purification method. Extraction involves the use of a purification solvent to remove overall permeable contaminants by creating a chemical potential gradient between the regenerated polymer and the solvent. The permeable chemical contaminant removal rate will depend on the diffusivity and solubility of the contaminant in the plastic under the conditions generated in the method. For high MW plastics, the diffusivity of the macromolecules indicating chemical contaminants is very low, especially in the solid state of the plastic. In addition, solubility may be limited due to the high MW of the regenerated polymer and the lack of enthalpy mixing. Therefore, the time required to remove permeable contaminants by diffusion mechanisms may be quite long and is not conducive to economically viable methods on a commercial scale. Methods to address these time scale limitations include 1) increasing the diffusivity by elevated temperature and / or increasing plastic relaxation by solvent swelling, 2) reducing the diffusion path length by increasing the average surface area to volume ratio of the regenerated polymer exposed to the solvent, and 3) increasing the convective transport of contaminants through the plastic / solvent interface by: increasing the solubility of the contaminant in the solvent, increasing the distribution of the contaminant in the solvent relative to the plastic; increasing the convection to the plastic / solvent interface, and increasing the solvent tank relative to the plastic tank. The solubility of the bulk purification solvent in the plastic can be increased by operating the extraction at elevated pressure, particularly at, near or above the critical pressure.

[0180] Importantly, the extraction method is scalable to large volumes at low cost. Therefore, the time required for extraction should be short to allow for this scalability. In embodiments of the present invention, the total 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 for each stage may be less than this range, but the total time will still fall within these times.

[0181] The extraction can be performed above, near, at or below the initial melting point of the recycled polymer. Extraction performed at, near or above the initial melting point of the recycled polymer is called liquid-liquid extraction. Extraction performed below the initial melting point of the recycled polymer is called leaching extraction, or simply the leaching process. The extraction solvent used in the leaching extraction is called the leaching solvent.

[0182] In the submerged leaching step of the present invention, the regenerated polymer is contacted with an excess solvent at each stage and during each time of the step. Such a leaching process is called a submerged leaching process. For the purposes of the present invention, "submerged leaching" and "leaching" can be used interchangeably. In addition, for the purposes of the present invention, "process", "step", "process step" and their plural forms can be used interchangeably.

[0183] In the leaching step, the mass of the leaching solvent is preferably equal to or greater than about 5:1 to the mass of the regenerated polymer exposed to the solvent at each time point and each stage of the method. In some leaching steps, the solvent is stirred rapidly so that the regenerated polymer is suspended in the solvent even when the density of the regenerated polymer is greater than the density of the solvent. Such leaching steps ensure complete contact between the surface of the regenerated polymer and the leaching solvent, and reduce the mass transfer resistance in the solvent boundary layer around the surface of the regenerated polymer due to convection motion. In addition to stirring, a similar reduced boundary layer can be achieved in the submerged leaching step by allowing the regenerated polymer to settle through the solvent with a density gradient. Examples of submerged leaching steps include continuous (also known as continuous stirred tank reactor-CSTR), semi-continuous and intermittent types of stirred tanks. Additional examples of submerged leaching steps include settling tanks, in which the regenerated polymer is settled out or passed through a solvent filled in a tank or other container. Applicants have found that for the submerged leaching step of the present invention, the mass ratio of the leaching solvent to the regenerated polymer at any time point and at any stage should preferably be greater than about 5:1, more preferably greater than 10:1 per stage, and most preferably greater than about 20:1, so that the regenerated polymer can be fully dispersed and exfoliated in the leaching solvent.

[0184] In an embodiment of the invention, the submerged leaching step is performed in a stirred tank. In an embodiment of the invention, the submerged leaching step is performed in a CSTR. In an embodiment of the invention, the submerged leaching step is performed in an intermittent stirred tank. For all stirred tank processes, the ability to expose the surface area of ​​the regenerated polymer to the leaching solvent is critical. The design of the reactor should include vigorous mechanical agitation and the potential use of a large number of baffles.

[0185] For the submerged leaching step of the present invention, it may be beneficial to select the leaching solvent and the operating temperature and pressure so that the leaching solvent is at its boiling point during extraction. Such a design allows for continuous reflux of the solvent, which can achieve local high concentration gradients when the refluxed solvent contacts the regenerated polymer.

[0186] In an embodiment of the present invention, the submerged leaching step is operated at a temperature lower than the initial melting point of the regenerated polymer and a pressure of about atmospheric pressure and about 1,000 atm. In an embodiment of the present invention, the submerged leaching step is operated at a temperature lower than the initial melting point of the regenerated polymer and a pressure of about atmospheric pressure. In an embodiment of the present invention, the submerged leaching step is operated at a temperature lower than the initial melting point of the regenerated polymer and a pressure of about atmospheric pressure and about 1,000 atm, using a leaching solvent in a plurality of leaching stages for the total residence time of the submerged leaching step and the residence time of each of the leaching stages.

[0187] In an embodiment of the present invention, the leaching solvent is at or near the normal boiling point. For polyolefin recycled polymers, the preferred leaching solvent for immersion leaching has 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 between 20°C and 90°C. In an embodiment of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C, and the leaching temperature is at or near the boiling point. In an embodiment of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C, the leaching temperature is at or near the boiling point, and the leaching pressure is about atmospheric pressure. For such leaching solvents, the pressure may also be higher than atmospheric pressure. In an embodiment of the present invention, the leaching solvent has a normal boiling point between 20°C and 90°C, and the leaching pressure is between above atmospheric pressure and about 1,000atm. The leaching solvent may also have a boiling point higher than the leaching temperature. In an embodiment of the present invention, the leaching solvent has a normal boiling point higher than the leaching temperature. In an embodiment of the present invention, the leaching solvent is ethyl acetate; the leaching temperature is between about 20°C and about 120°C. And the leaching pressure is between about atmospheric pressure and about 1,000atm. In an embodiment of the present invention, the leaching temperature is between about 20°C and about 90°C, and the leaching pressure is between about atmospheric pressure and about 1,000atm, the leaching solvent is ethyl acetate, the total residence time of the leaching step is less than about 360min, and the average removal efficiency is about 55%. In an embodiment of the present invention, the leaching solvent is hexane; the leaching temperature is between about 20°C and about 120°C. And the leaching pressure is between about atmospheric pressure and about 1,000atm.

[0188] Due to the increased immersion leaching pressure, leaching solvents having a normal boiling point lower than the leaching temperature are also preferred. In an embodiment of the present invention, the leaching solvent has a normal boiling point lower than the leaching temperature. In an embodiment of the present invention, the leaching solvent is propane. In an embodiment of the present invention, the leaching solvent is propane; the leaching temperature is between about 20°C and about 120°C. And the leaching pressure is between about 9atm and about 1,000atm. In an embodiment of the present invention, the leaching solvent is dimethyl ether (DME). In an embodiment of the present invention, the leaching solvent is DME; the leaching temperature is between about 20°C and about 120°C; and the leaching pressure is between about 6atm and about 1,000atm.

[0189] Leaching solvents having a standard boiling point lower than the leaching temperature and a critical temperature lower than the leaching temperature are also preferred. In an embodiment of the present invention, the leaching solvent has a standard boiling point lower than the leaching temperature and its critical temperature is lower than the leaching temperature. In an embodiment of the present invention, the leaching solvent is ethane. In an embodiment of the present invention, the leaching solvent is critical or supercritical ethane. In an embodiment of the present invention, the leaching solvent is ethane; the leaching temperature is between about 31°C and about 120°C; and the leaching pressure is between about 40atm and about 1,000atm. In an embodiment of the present invention, the leaching solvent is CO2. In an embodiment of the present invention, the leaching solvent is CO2, the leaching temperature is between about 31°C and about 120°C; and the leaching pressure is between about 68atm and about 1,000atm. In an embodiment of the present invention, the leaching solvent is CO2 with less than 5% by weight water.

[0190] The density of the leaching solvent is preferably less than the density of the recycled polymer at the temperature and pressure of the submerged leaching step. For recycled polyethylene, the density of the leaching solvent at the temperature and pressure of the submerged leaching step is preferably less than about 0.90 g / mL, although higher densities may be used.

[0191] Preferred leaching solvents include solvents with a higher affinity for chemical contaminants than for regenerated polymers. Solvents with a high affinity for chemical contaminants of concern in regenerated polyolefins, relative to their affinity for polyolefins, include but are not limited to diethyl ether, MEK, ethyl acetate, THF, acetone, methylene chloride and methanol. Other oxygenated and polar hydrocarbon solvents may have similar desired affinities. Solvents lacking such properties may still be used, but a higher solvent to polymer ratio may be required. Preferably, the solvent should not significantly dissolve the regenerated polymer (less than about 5 wt % soluble) at the temperature and pressure of the immersion leaching step.

[0192] 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 including hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group including aliphatic hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group including aromatic hydrocarbons. In an embodiment of the present invention, the leaching solvent is selected from the group including alkanes. In an embodiment of the present invention, the leaching solvent is selected from the group including methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, hexane (n-hexane, isohexane, neohexane), heptane, octane or a mixture thereof. In an embodiment of the present invention, the leaching solvent is at least one of DME, diethyl ether, MEK, ethyl acetate, THF, acetone, methanol and CO2 or a mixture thereof.

[0193] The temperature may vary during the course of the submerged leaching step, but is generally consistent within a given stage of the unit operation. The pressure may be varied to change the solubility of the leaching solvent in the recycled polymer or to increase the solubility of chemical contaminants in the leaching solvent.

[0194] The submerged leaching extraction process can be carried out in stages and combined with other types of additional leaching steps not discussed in the present disclosure. The same is true for liquid-liquid extraction methods. In addition, the liquid-liquid extraction process can be combined with submerged leaching steps at various stages to form a given purification method. In an embodiment of the present invention, the number of leaching stages is more than one. In an embodiment of the present invention, the number of leaching stages is between about 1 and about 50. In an embodiment of the present invention, the number of leaching stages is between about 2 and about 30. In an embodiment of the present invention, the number of leaching stages is between about 5 and about 20. In an embodiment of the present invention, the number of liquid-liquid stages is more than one. In an embodiment of the present invention, the number of leaching stages is more than one. In an embodiment of the present invention, the number of liquid-liquid stages is one or more, and the number of leaching stages is one or more.

[0195] A single stirred tank reactor will achieve a certain removal efficiency. The efficiency can be improved by having multiple stirred tank reactors in series, where the recycled polymer from stage 1 is primarily separated from the stage 1 leaching solvent, and the stage 1 plastic is used in stage 2 with fresh leaching solvent. This is repeated for each additional stage. The process increases removal efficiency at the expense of additional reactors and complexity, but maintains overall time, throughput, and solvent utilization. In practice, the number of reactor stages can be anywhere from 1 to about 10 for a stirred tank system. If a larger number of stages is desired, a continuous countercurrent process can be used.

[0196] While not wishing to be bound by theory, the theoretical maximum contaminant removal capacity of the submerged leaching step is based on the thermodynamic equilibrium / partitioning of chemical contaminants between the regenerated polymer and the leaching solvent at the temperature and pressure of the submerged leaching step. Due to kinetic limitations in the submerged leaching step, thermodynamic equilibrium may not be achieved. This is true for the overall submerged leaching step, and for each submerged leaching stage as well. A higher leaching solvent to regenerated polymer mass ratio will drive thermodynamics and kinetics in favor of leaching at the expense of greater leaching solvent consumption and larger leaching process size, which equals greater cost. Therefore, a balance must be found between these important design and operating variables for the removal efficiency of a selected chemical contaminant.

[0197] In general, applicants have found that the mass ratio of total fresh or renewed leaching solvent to recycled polymer is preferably greater than about 5: 1. In embodiments of the invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 10: 1. In embodiments of the invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 15: 1. In embodiments of the invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 20: 1. In embodiments of the invention, the mass ratio of total fresh or renewed leaching solvent to recycled polymer is greater than about 30: 1 and less than about 100: 1.

[0198] If submerged leaching is done in stepwise or sequential stages, the ratio of leaching solvent to recycled polymer for each stage may be lower than this specified range (but still above the minimum of about 5:1 per stage), but the total solvent used in the total recycled polymer represented by the sum of the solvents used in all stages should be within this range. In addition, contaminated solvent from any stage can be used "as is" as solvent in another stage. Contaminated solvent at any point in the process can be renewed by known methods or combinations of distillation, filtration, ion exchange, etc.

[0199] Another important kinetic driver is the average surface area to volume ratio of the regenerated polymer within and exposed to the leaching solvent. In general, the time required to extract chemical contaminants from the regenerated polymer is a strong function of the diffusion path length within the regenerated polymer. The diffusion path length is indirectly proportional to the average surface area to volume ratio of the geometry of the regenerated polymer and the ability to access the surface area with the leaching solvent. Therefore, a higher average surface area to volume ratio will produce a reduced diffusion path length and faster diffusion kinetics. For the submerged leaching step, a high average surface area to volume ratio is a key parameter for rapid and efficient removal of surface and bulk contaminants.

[0200] For the submerged leaching step, since the processing temperature is below the initial melting point, the average surface area to volume ratio of the regenerated polymer within and exposed to the extraction solvent is substantially the same as the average surface area to volume ratio of the regenerated polymer. For membrane-based regenerated polymers, the submerged leaching step is ideal because of the extremely high inherent average surface area to volume ratio. If the regenerated polymer is provided in other forms with a lower average surface area to volume ratio, such as pellets, granular bottles, granular parts, etc., it would be advantageous to increase the surface area to volume ratio by various means. These means include, but are not limited to, mechanical grinding, cryogenic grinding, calendaring, pressing, stretching, etc.

[0201] A known method of increasing the effective mass transfer at the regenerated polymer-leaching solvent interface with a given surface area to volume ratio and a given set of conditions is by applying energy to the regenerated polymer, such as but not limited to ultrasonic energy and / or vibrations in the form of microwaves.

[0202] After the submerged leaching step, the leached polymer can be devolatilized to remove the leaching solvent. The contaminated leaching solvent will contain small amounts of dissolved regenerated polymer, leached contaminants, and pure leaching solvent. There are many methods for recovering purer polymer and leaching solvent independent of the leached contaminants.

[0203] Typically, regardless of the type of process or leaching solvent, a small amount of regenerated polymer can be dissolved into the leaching solvent. In particular, low MW waxes are particularly susceptible to dissolution into the leaching solvent. Due to the deposition of wax on the processing equipment, these may become a problem in the distillation-based recovery of the purified leaching solvent. Methods are known to reduce this tendency. One such method is to reduce the temperature of the contaminated leaching solvent to below the cloud point to precipitate the polymer or wax phase and then filter. Unlike regenerated polymers, the residual plastic or wax produced by the precipitation of the contaminated solvent may contain significant contamination.

[0204] Distillation of the contaminated leaching solvent can be used to regenerate the leaching solvent for reuse in various leaching operations. However, considering the high leaching solvent volume used in the present invention, distillation may not be economically feasible. In addition, because the concentration of the chemical contaminants concerned in the present invention is extremely low, the concentration of these chemical contaminants in the contaminated leaching solvent can be correspondingly low or even lower. Therefore, the preferred method for purifying the contaminated leaching solvent is by directly removing the contaminants without volatilizing the overall leaching solvent phase. Such methods include ion exchange, adsorption / absorption methods, etc. Examples include passing the contaminated leached solvent through activated carbon, alumina or activated alumina beds. This method can be used alone or in combination with distillation to achieve the correct purification level at the correct energy consumption. In addition, the contaminated leaching solvent from any leaching stage can be used as the leaching solvent of another stage "as is". The contaminated leaching solvent at any point in the method can be updated by known methods or combinations such as distillation, filtration, ion exchange, etc.

[0205] The leached polymer may contain a small amount of leached solvent in the form of physical adsorption or bulk adsorption. The concentration of leached solvent in the leached polymer can be reduced by devolatilization technology. In an embodiment of the present invention, the leached polymer is devolatilized to a content of less than 1% by weight of leached solvent in the regenerated polymer.

[0206] Stirred tank reactors operating at the boiling point of the leaching solvent provide improvements over existing processes. For example (Examples 1, 2, 3 and 4 and Tables 7, 8, 9 and 10), submerged leaching steps with ethyl acetate or THF provide greater than about 88% removal efficiency of selected contaminants.

[0207] In an embodiment of the present invention, the leaching solvent is ethyl acetate. In an embodiment of the present invention, the leaching solvent is ethyl acetate, and the leaching pressure is about atmospheric pressure. In an embodiment of the present invention (Example 1 and Table 7), the submerged leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is about atmospheric pressure, and the leaching solvent includes ethyl acetate. In an embodiment of the present invention, the submerged leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is about atmospheric pressure, and the leaching solvent includes ethyl acetate; wherein the recycled polymer has about 80 mm -1 the surface area to volume ratio of the polymer is 2; the number of leaching stages is 2, the mass ratio of ethyl acetate to recycled polymer in each stage is about 18:1, the immersion leaching residence time in each stage is about 50 min, the mass ratio of total ethyl acetate to recycled polymer is about 36:1, and the total residence time is about 100 min; and the average value of the concentration reduction of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and di-2-ethylhexyl phthalate is about 89%.

[0208] In the embodiment of the present invention (Example 2 and Table 8), the submerged leaching step is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is about atmospheric pressure, and the leaching solvent includes ethyl acetate; wherein the regenerated polymer has a thickness of about 80 mm -1 the surface area to volume ratio of the polymer is 2; the number of leaching stages is 2, the mass ratio of ethyl acetate to recycled polymer in each stage is about 18:1, the immersion leaching residence time in each stage is about 30 min, the mass ratio of total ethyl acetate to recycled polymer is about 36:1, and the total residence time is about 60 min; and the average value of the concentration reduction of 4-tert-amylphenol, bisphenol A, OCDD, PCB118 and di-2-ethylhexyl phthalate is about 89%.

[0209] In an embodiment of the present invention, the leaching solvent is THF. In an embodiment of the present invention, the leaching solvent is THF and the leaching pressure is about atmospheric pressure. In an embodiment of the present invention, the submerged leaching is carried out in a stirred tank, the leaching temperature is about 66°C, the leaching pressure is about atmospheric pressure, and the leaching solvent includes THF. In an embodiment of the present invention (Example 3 and Table 9), the submerged leaching step is carried out in a stirred tank, the number of leaching stages is 2, the leaching temperature is about 66°C, the leaching pressure is about atmospheric pressure, the leaching solvent includes THF, and the regenerated polymer has about 80 mm -1The surface area to volume ratio of the leaching agent is about 100:1, the THF to recycled polymer ratio is about 18:1 in each stage, the residence time in each leaching stage is about 50 min, the total THF to recycled polymer mass ratio is about 36:1, and the total residence time of the immersion leaching step is about 100 min; and the average value of the concentration reduction of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and di-2-ethylhexyl phthalate is about 90%.

[0210] In an embodiment of the present invention, the leaching solvent is DME, the leaching temperature is about 70°C, and the leaching pressure is greater than about 18 atm. In an embodiment of the present invention, the leaching solvent is DME, and the regenerated polymer has a molecular weight of about 80 mm. -1 The surface area to volume ratio of the leaching solvent is about 70°C, the leaching temperature is about 70°C, and the leaching pressure is greater than about 18 atm. In an embodiment of the present invention, the leaching solvent is CO2, the leaching temperature is about 70°C, the leaching pressure is about 340 atm, and the recycled polymer has a surface area to volume ratio of about 80 mm -1 The ratio of surface area to volume.

[0211] After the submerged leaching step, the leached polymer can be physically wetted by the residual leaching solvent and may contain a small amount of absorbed leaching solvent. As discussed above, there are many methods for recovering leached polymer and leaching solvent that are independent of leaching pollutants. The leached polymer can be dried and devolatilized by many known commercial means. One method is by cyclone drying. Another method is by melt extrusion with a devolatilization stage. In an embodiment of the present invention, the leached polymer is processed to reduce the leaching solvent in the regenerated polymer to less than about 1 weight %. The contaminated leaching solvent can be cleaned with known distillation methods, ion exchange, filtration, etc. The resulting devolatilized regenerated polymer can be used as is or can be further processed into other forms, including pellets, by various methods.

[0212] In an embodiment of the invention, the total residence time of the leaching step is less than about 600 min. In an embodiment of the invention, the total residence time of the leaching step is less than about 480 min. In an embodiment of the invention, the total residence time of the leaching step is less than about 360 min. In an embodiment of the invention, the total residence time of the leaching step is less than about 180 min. In an embodiment of the invention, the total residence time of the leaching step is less than about 60 min.

[0213] In an embodiment of the present invention, the residence time of each leaching step in the leaching steps is less than about 180 minutes. In an embodiment of the present invention, the residence time of each leaching step in the leaching steps is less than about 90 minutes. In an embodiment of the present invention, the residence time of each leaching step in the leaching steps is less than about 60 minutes. In an embodiment of the present invention, the residence time of each leaching step in the leaching steps is less than about 30 minutes. In an embodiment of the present invention, the residence time of each leaching step in the leaching steps is about 20 minutes.

[0214] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; and b) leaching the alkylphenols, bisphenols, dioxins, PCBs, or phthalates from the recycled polymer with an average removal efficiency using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm over a total residence time and a residence time in each of the leaching stages to produce a leached polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, each having a certain concentration; and wherein the average removal efficiency is greater than about 55%.

[0215] In an embodiment of the invention, wherein the leaching step is performed in a continuous stirred tank reactor (CSTR); wherein the regenerated polymer is surface washed in a non-densified state in a surface washing process prior to extraction; wherein the surface washing process results in a reduction of loosely bound surface contamination by greater than about 80%; wherein the regenerated polymer has a surface area greater than about 1 mm prior to surface washing. -1 wherein the surface washing process is of the deinking type; wherein the deinking process results in a ΔE variation of less than about 10% between the deinked polymer and the regenerated polymer without surface printing ink; wherein the leaching solvent is ethyl acetate; wherein the CSTR comprises 3 leaching stages; wherein the leaching temperature is about 77°C and the leaching pressure is close to atmospheric pressure; wherein the residence time of each of the leaching stages is about 20 minutes; wherein the regenerated polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets; and wherein the average removal efficiency is greater than about 55%.

[0216] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of a post-consumer recycled (PCR) polymer, a post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; and b) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer with an average removal efficiency at a total residence time and a residence time in each of the leaching stages using a leaching solvent at a temperature below an initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm in a plurality of leaching stages to produce a recycled polymer comprising 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. The leached polymer of at least one of 118 and 2-ethylhexyl phthalate, each having a concentration; wherein the average removal efficiency is greater than about 55%.

[0217] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) treating the recycled polymer with a temperature below the initial melting point of the recycled polymer and at about atmospheric pressure and about 1, 000 atm, leaching the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs from the recycled polymer with an average removal efficiency over a total residence time and a residence time in each of the leaching stages using a leaching solvent in a plurality of leaching stages to produce a leached polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs, each having a certain concentration; and wherein the average removal efficiency of the leached polymer is greater than about 55%.

[0218] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) treating the recycled polymer with a temperature below the initial melting point of the recycled polymer and at about atmospheric pressure and about 1, 000atm, leaching the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs from the recycled polymer with an average removal efficiency over a total residence time and a residence time in each of the leaching stages using a leaching solvent in a plurality of leaching stages to produce a leached polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs, each having a certain concentration; and wherein the average removal efficiency of the leached polymer is greater than about 70%.

[0219] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) treating the recycled polymer with a temperature below the initial melting point of the recycled polymer and at about atmospheric pressure and about 1, and 000 atm, leaching the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs from the recycled polymer with an average removal efficiency over a total residence time and a residence time in each of the leaching stages using a leaching solvent in a plurality of leaching stages to produce a leached polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs, each having a certain concentration; and wherein the average removal efficiency of the leached polymer is greater than about 80%.

[0220] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates, and polycyclic aromatic hydrocarbons (PAHs); and b) treating the recycled polymer with a temperature below the initial melting point of the recycled polymer and at about atmospheric pressure and about 1, 000 atm, leaching the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs from the recycled polymer with an average removal efficiency over a total residence time and a residence time in each of the leaching stages using a leaching solvent in a plurality of leaching stages to produce a leached polymer comprising at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotin, phthalates and PAHs, each having a certain concentration; and wherein the average removal efficiency of the leached polymer is greater than about 90%.

[0221] VII. Combination of surface purification and immersion leaching processes

[0222] Typically, the combination of a surface purification step and an immersion leaching step provides a synergistic benefit in the overall removal of contamination. The surface purification step will effectively remove both impermeable and permeable surface contamination, including chemical contaminants and chemical contaminant precursors. Therefore, surface purification reduces the burden of the immersion leaching step and makes it more effective. If the regenerated polymer is heavily contaminated with surface contaminants, it is preferred to first remove such contamination in a surface purification step and then an immersion leaching step. Once the surface contaminants are removed in the surface purification step, the remaining overall permeable contamination will be removed by the immersion leaching step. The only contamination that is not significantly removed by this two-step process is overall impermeable contamination, such as heavy metals that were intentionally added during the production of the original plastic parts.

[0223] Preferred methods for surface washing have been discussed in the surface purification section. An even more preferred surface washing method is the deinking method also described in the surface purification method (Comparative Example 3). This method not only removes surface contamination, such as dirt, but also removes surface-printed ink. This method is also quite effective in removing paper labels that are precursors of chemical contaminants. In this method, a regenerated polymer with an exposed original surface area is fed into a multi-step aqueous washing method, wherein surface contamination including surface-printed ink, dirt, grit, paper, adhesives, etc. is removed. The resulting material is then dried. Extrusion including devolatilization and melt filtration can be used to further densify the dried material into pellets. For the purposes of the present invention, the deinking method is any surface washing method, wherein the method removes surface imprints sufficient to produce a ΔE difference of less than about 10% between the deinked regenerated polymer and the unprinted regenerated polymer (ΔE measured using method 3 in Part IX).

[0224] For nomenclature purposes, the regenerated polymer is fed to the surface purification process, and the resulting surface purified polymer will be referred to as the surface washed polymer. The surface washed polymer is then fed to the immersion leaching step, and the resulting polymer is referred to as the leached polymer. The surface purification process may involve multiple surface purification processes. The immersion leaching process may involve multiple immersion leaching steps of various types. The removal efficiency of the combined surface purification and immersion leaching steps will be calculated by the regenerated polymer concentration and the associated leached polymer. The combination of surface washing and immersion leaching steps provides an average reduction of about 95% in the concentration of bisphenol A, 4-tert-amylphenol, OCDD, PCB 108, and di-2-ethylhexyl phthalate (Example 4 and Table 10).

[0225] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises: a) obtaining a regenerated polymer; wherein the regenerated polymer is selected from a PCR polymer, a PIR polymer, and a combination thereof. And wherein the regenerated polymer contains contaminants, each of which has a certain concentration; and wherein the regenerated polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) surface washing the regenerated polymer to produce a surface washed polymer; and c) using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the regenerated polymer and a pressure between about atmospheric pressure and about 1,000 atm to leach the alkylphenols, bisphenols, dioxins, PCBs, and phthalates from the surface washed polymer with an average removal efficiency in a total residence time and a residence time in each of the leaching stages to produce a leached polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates, each having a certain concentration; and wherein the average value of the concentration reduction is greater than about 55%.

[0226] In an embodiment of the present invention, the submerged leaching step is performed after surface washing. In an embodiment of the present invention, the submerged leaching step is performed after the surface washing process; and wherein the regenerated polymer is not densified before the surface washing process. In an embodiment of the present invention, the submerged leaching is performed after the surface washing process; wherein the regenerated polymer is not densified before the surface washing process; and wherein the surface washed regenerated polymer may be densified before the submerged leaching step.

[0227] In an embodiment of the invention, the submerged leaching step uses a leaching solvent at a certain temperature and pressure; wherein the submerged leaching step is operated in multiple stages; and wherein the regenerated polymer has been partially purified using a surface washing process.

[0228] In an embodiment of the present invention (Example 4 and Table 10), the surface washing process involves deinking commercially available by Cadel; the deinking results in a ΔE change of less than about 10% and a removal of loosely bound surface contaminants greater than about 80%; the immersion leaching step is operated in a stirred tank; the leaching temperature is about 77.1°C; the leaching pressure is about atmospheric pressure; the leaching solvent includes ethyl acetate; and the total residence time is about 60 min. In an embodiment of the present invention, the surface washing involves deinking commercially available by Cadel; the deinking results in a ΔE change of less than about 10% and a removal of loosely bound surface contaminants greater than about 80%; the immersion leaching step is operated in a stirred tank and involves 2 stages; the leaching temperature is about 77.1°C; the leaching pressure is about atmospheric pressure; the leaching solvent includes ethyl acetate; the residence time for each stage is about 30 min; the concentration reduction of OCDD is about 98%.

[0229] In an embodiment of the present invention, the surface washing process comprises any known surface washing method; the submerged leaching step uses a stirred tank; and the submerged leaching step uses a leaching solvent. In an embodiment of the present invention, the submerged leaching step uses a stirred tank and comprises multiple leaching stages.

[0230] In an embodiment of the invention, wherein prior to the leaching step, the regenerated polymer is surface washed in a surface washing step in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contamination by greater than about 80%; wherein the regenerated polymer has a surface area greater than about 1 mm prior to surface washing. -1wherein the surface washing process is of the deinking type; wherein the deinking process results in a ΔE variation of less than about 10% between the deinked polymer and the regenerated polymer without surface printing ink; wherein the leaching step is carried out in a continuous stirred tank reactor (CSTR); wherein the leaching solvent is ethyl acetate; wherein the CSTR comprises 3 leaching stages; wherein the leaching temperature is about 77°C and the leaching pressure is close to atmospheric pressure; wherein the residence time of each of the leaching stages is about 20 minutes; wherein the average removal efficiency is greater than about 55%; and wherein the leached polymer is devolatilized and densified using melt extrusion to produce leached polymer pellets.

[0231] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; and c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer with an average removal efficiency of 1% to 20% at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm in a plurality of leaching stages using a leaching solvent at a total residence time and a residence time in each of the leaching stages. 118 and 2-ethylhexyl phthalate to produce a leached polymer comprising at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate, each having a certain concentration; wherein the average removal efficiency is greater than about 55%.

[0232] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining recycled polyethylene; wherein the recycled polyethylene is post-consumer recycled (PCR) polyethylene; and wherein the recycled polyethylene comprises contaminants, each contaminant having a certain concentration; and wherein the recycled polymer contaminants comprise at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotin, phthalates, and polycyclic aromatic hydrocarbons (PAHs); 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 8 0%; and c) leaching the pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates and PAHs from the regenerated polymer with an average removal efficiency within a total residence time using ethyl acetate in a countercurrent auger extraction at a temperature of about 55° C. and about 65° C. and a pressure of about atmospheric pressure to produce a leached 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 certain concentration; wherein the average removal efficiency of the leached polymer is greater than about 90%.

[0233] VIII. Dissolution Recycling Process - Purification of Leached Polymers

[0234] Surprisingly, it has been found that leached polymer in a high MW polymer solution can be purified by filtration. Figure 1A and Figure 1B The process illustrated in the example comprises: 1) extracting the leached polymer with a fluid solvent at an extraction temperature and extraction pressure to produce an extracted polymer ( Figure 1A Step c and Figure 1B 2) dissolving the extraction polymer in a fluid solvent at a dissolution temperature and a dissolution pressure to produce a solution of the extraction polymer ( Figure 1A Step d and Figure 1B 3) allowing the solution of the extracted polymer to settle at a dissolution temperature and dissolution pressure to produce a solution of the settled polymer ( Figure 1A Step e and Figure 1B 4) filtering the solution of the precipitated polymer at the dissolution temperature and dissolution pressure to produce a solution of the filtered polymer ( Figure 1A Step f and Figure 1B and 5) separating the filtered polymer from the fluid solvent to produce a purer polymer ( Figure 1A Steps g and Figure 1BIt should be noted that the above-mentioned temperature and pressure values ​​may vary from one step to another. A schematic diagram of the experimental apparatus used in the extraction step is shown in Figure 3A A schematic diagram of the experimental setup used in the dissolution, sedimentation, filtration and separation steps is shown in Figure 3B Shown in.

[0235] The dissolution recycling process includes extraction, dissolution, sedimentation, filtration and separation steps performed in various orders. In embodiments of the present invention, the purer polymer that can be derived from the PCR stream is substantially free of contaminants, free of pigments, free of odors, uniform, and has properties similar to the virgin polymer.

[0236] Fluid solvent

[0237] 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 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 and a normal enthalpy of vaporization of less than about +25 kJ / mol. Pressurization places solvents having a normal boiling point below the operating temperature range of the invention in a state with little or no solvent vapor.

[0238] In an embodiment of the present invention, the fluid solvent is selected from olefins, aliphatic hydrocarbons, and mixtures thereof. In an embodiment of the present invention, the aliphatic hydrocarbons of the fluid solvent are selected from C1-C6 aliphatic hydrocarbons and mixtures thereof. In an embodiment of the present invention, the fluid solvent comprises n-butane, butane isomers or mixtures thereof.

[0239] In an embodiment of the present invention, the fluid solvent having a normal boiling point of less than about 70° C. is selected from carbon dioxide, ketones, alcohols, ethers, esters, olefins, alkanes, and mixtures thereof. Non-limiting examples of fluid solvents having a normal boiling point below about 70° C. are carbon dioxide, acetone, methanol, dimethyl ether, diethyl ether, ethyl methyl ether, tetrahydrofuran, methyl acetate, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, branched isomers of pentene, 1-hexene, 2-hexene, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isomers of isohexane, and other substances that may be obvious to those of ordinary skill in the art.

[0240] The selection of an appropriate fluid solvent or solvent mixture will depend on which polymer or polymer mixture is being purified by the present invention. In addition, the selection of the polymer being purified and the corresponding fluid solvent used will determine the temperature and pressure range for performing the steps of the present invention. The following reference provides an overview of the phase characteristics of polymers in fluid solvents of the type described in the present invention: McHugh et al. (1999) Chem. Rev. 99: 565-602.

[0241] extract

[0242] In an embodiment of the present invention, the method for purifying the leached polymer comprises contacting the leached polymer with a fluid solvent at a certain temperature and pressure, wherein the leached polymer is substantially insoluble in the fluid solvent. Although not wishing to be bound by any theory, the applicant believes that the temperature and pressure dependent solubility can prevent the fluid solvent from completely dissolving the leached polymer in a controlled manner, however, the fluid solvent can diffuse into the leached polymer and extract any extractable pollutants. Extractable pollutants can be residual processing aids added to the polymer, residual product preparations such as spices and flavorings, dyes that contact the polymer, and any other extractable materials that may have been intentionally added or accidentally incorporated into the polymer during waste collection and subsequent other waste accumulation.

[0243] In embodiments of the present invention, controlled extraction can be accomplished by fixing the temperature of the polymer / fluid solvent system, and then controlling the pressure to be lower than the pressure or pressure range in which the polymer dissolves in the fluid solvent. In embodiments of the present invention, controlled extraction can be accomplished by fixing the pressure of the polymer / solvent system, and then controlling the temperature to be lower than the temperature or temperature range in which the polymer dissolves in the fluid solvent. The temperature and pressure controlled extraction of the leached polymer with the fluid solvent uses a suitable pressure vessel, and the configuration of the mode of the leached polymer can be allowed to be continuously extracted with the fluid solvent. In embodiments of the present invention, the pressure vessel can be a continuous liquid-liquid extraction column, wherein the molten polymer is pumped into one end of the extraction column, and the fluid solvent is pumped into the same or opposite end of the extraction column. In embodiments of the present invention, the fluid containing the pollutant extracted is removed from the process. In embodiments of the present invention, the fluid containing the pollutant extracted is purified, recovered and recycled for use in the extraction step or the different steps in the process. In embodiments of the present invention, extraction can be carried out in an intermittent method, wherein the leached polymer is fixed in a pressure vessel, and the fluid solvent is continuously pumped through the fixed polymer phase. The amount of the extraction time or the fluid solvent used will depend on the desired purity of the final purer polymer and the amount of extractable pollutants in the initial leached polymer. In an embodiment of the present invention, the fluid containing the pollutants extracted contacts with a solid medium in a separate step as described below. In an embodiment of the present invention, the method for purifying the leached polymer comprises contacting the leached polymer with a fluid solvent at a certain temperature and pressure, wherein the leached polymer is molten and in a liquid state. In an embodiment of the present invention, the leached polymer contacts with a fluid solvent at a certain temperature and pressure, wherein the leached polymer is in a solid state.

[0244] 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 a pressure, wherein the polyethylene remains substantially 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 a pressure, wherein the leached polymer remains substantially 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 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 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 about 150psig (1.03MPa) to about 8,000psig (55.16MPa). 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 about 400psig (2.76MPa) to about 2,400psig (16.55MPa). In an embodiment of the invention, the pressure during the extraction step is less than about 1,100 psig (7.58 MPa).

[0245] In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a temperature of about 80°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a pressure of about 400psig (2.76MPa) to about 6,000psig (41.37MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-butane at a pressure of about 800psig (5.52MPa) to about 5,000psig (34.47MPa). 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 about 1,000 psig (6.89 MPa) to about 4,500 psig (31.03 MPa).

[0246] In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a temperature of about 80°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a pressure of about 400psig (2.78MPa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polyethylene with n-pentane at a pressure of about 800psig (5.52MPa) to about 2,800psig (19.31MPa). 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 about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0247] In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a temperature of about 80°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a pressure of about 150psig (1.03Pa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a pressure of about 1,000psig (6.89MPa) to about 2,750psig (18.96MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with n-butane at a pressure of about 1,500 psig (10.34 MPa) to about 2,500 psig (17.24 MPa).

[0248] In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a temperature of about 80°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a pressure of about 200psig (1.38MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a pressure of about 1,000psig (6.89MPa) to about 6,000psig (41.37MPa). In an embodiment of the invention, a method for purifying a leached polymer comprises contacting the leached polypropylene with propane at a pressure of about 2,000 psig (13.79 MPa) to about 4,000 psig (27.58 MPa).

[0249] In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with a fluid solvent at a temperature and a pressure, wherein the polystyrene remains substantially undissolved. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a temperature of about 120°C to about 180°C. In an embodiment of the present invention, a method for purifying a leached polymer comprises contacting the leached polystyrene with n-butane at a pressure of about 500psig (3.45MPa) to about 5,000psig (34.47MPa). 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 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 about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0250] In an embodiment of the invention, a method for purifying a leached polymer comprises contacting a leached poly(dimethylsiloxane) with a fluid solvent at a temperature and a pressure wherein the poly(dimethylsiloxane) remains substantially undissolved. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting a leached poly(dimethylsiloxane) with n-butane at a temperature of about 100°C to about 280°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting a leached poly(dimethylsiloxane) with n-butane at a temperature of about 115°C to about 220°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting a leached poly(dimethylsiloxane) with n-butane at a temperature of about 120°C to about 180°C. In an embodiment of the invention, a method for purifying a leached polymer comprises contacting a leached poly(dimethylsiloxane) with n-butane at a pressure of 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 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 about 500 psig (3.45 MPa) to about 1,000 psig (6.89 MPa).

[0251] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises extracting a 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.

[0252] Dissolve

[0253] In embodiments of the present invention, the method for purifying regenerated polymers is included in a certain temperature and pressure place to dissolve the extracted polymer in a fluid solvent, wherein the polymer is dissolved in the fluid solvent. Although it is not desired to be bound by any theory, the applicant believes that the temperature and pressure can be controlled in a thermodynamically favorable dissolving mode of the regenerated polymer in the fluid solvent. In addition, the temperature and pressure can be controlled in a way that a specific polymer or polymer mixture can be dissolved without dissolving other polymers or polymer mixtures. This controlled dissolving can separate the polymer from the polymer mixture.

[0254] In an embodiment of the invention, the method for purifying the extracted polymer comprises dissolving the extracted polymer in a fluid solvent that does not dissolve pollutants under the same temperature and pressure conditions. The pollutants may include pigments, fillers, dirt and other polymers. These pollutants are released from the extracted polymer after dissolution and then removed from the polymer solution by a subsequent solid-liquid separation step.

[0255] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in a fluid solvent at a certain temperature and pressure, wherein the polyethylene is dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a pressure of about 200psig (1.38MPa) to about 9,000psig (62.05MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polymer in a fluid solvent at a pressure of about 400psig (2.76MPa) to about 2,600psig (17.93MPa).

[0256] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the 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 the 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 the 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 the extracted polyethylene in n-butane at a pressure of about 4,000psig (27.58MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in n-butane at a pressure of about 4,200psig (28.96MPa) to about 7,000psig (48.26MPa). In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in n-butane at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0257] In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polyethylene in n-butane at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polyethylene in n-butane at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 12%.

[0258] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in propane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in propane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in propane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in n-pentane at a pressure of about 800psig (5.52MPa) to about 4,000psig (27.58MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in n-pentane at a pressure of about 900psig (6.21MPa) to about 3,000psig (20.68MPa). In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving the extracted polyethylene in n-pentane at a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0259] In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polyethylene in n-pentane at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polyethylene in n-pentane at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the extracted polyethylene is dissolved at a mass percentage concentration of up to 12%.

[0260] 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 certain temperature and pressure, wherein the polypropylene is dissolved 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 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 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 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 about 350psig (2.41MPa) to about 4,000psig (27.57MPa). 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 about 1,000psig (6.89MPa) to about 3,500psig (24.13MPa). In an embodiment of the invention, a method for purifying an extracted polymer comprises dissolving polyextracted propylene in n-butane at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0261] In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polypropylene in n-butane at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polypropylene in n-butane at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 12%.

[0262] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the 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 the 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 the 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 the extracted polypropylene in propane at a pressure of about 2,000psig (13.79MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polypropylene in propane at a pressure of about 3,000psig (20.68MPa) to about 6,000psig (41.37MPa). In an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted polypropylene in propane at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0263] In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polypropylene in propane at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the extracted polymer comprises dissolving the extracted polypropylene in propane at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the extracted polypropylene is dissolved at a mass percentage concentration of up to 12%.

[0264] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in a fluid solvent at a temperature and pressure, wherein the extracted polystyrene is dissolved in a fluid solvent. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a pressure of about 1,000psig (6.89MPa) to about 9,000psig (62.05MPa). In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving the extracted polystyrene in n-butane at a pressure of about 2,000psig (13.79MPa) to about 8,000psig (55.16MPa). In an embodiment of the invention, a method for purifying the extracted polymer comprises dissolving the extracted polystyrene in n-butane at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0265] In an embodiment of the present invention, a method for purifying extracted polystyrene comprises dissolving the extracted polystyrene in n-butane at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, a method for purifying extracted polystyrene comprises dissolving the extracted polystyrene in n-butane at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the extracted polystyrene is dissolved at a mass percentage concentration of up to 12%.

[0266] In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving an extracted poly(dimethylsiloxane) in a fluid solvent at a temperature and pressure, wherein the extracted poly(dimethylsiloxane) is dissolved in a fluid solvent. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving an extracted poly(dimethylsiloxane) in n-butane at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving an extracted poly(dimethylsiloxane) in n-butane at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving an extracted poly(dimethylsiloxane) in n-butane at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying an extracted polymer comprises dissolving an 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).

[0267] 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 mass percent concentration of at least 0.5%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass 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 mass percent concentration of up to 20%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the extracted poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0268] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises dissolving the extracted polymer in a solvent selected from a first fluid solvent, a second fluid solvent, and a mixture thereof at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising a dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant.

[0269] In an embodiment of the invention, the extraction polymer is dissolved in a fluid solvent or a fluid solvent mixture at a mass percent concentration of at least 0.5%. In an embodiment of the invention, the temperature in the dissolving step is from about 110° C. to about 220° C. In an embodiment of the invention, the pressure in the dissolving step is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0270] settlement

[0271] In an embodiment of the present invention, a method for purifying a polymer comprises separating undissolved contaminants from a polymer solution via a sedimentation step at a temperature and pressure, wherein the polymer remains dissolved in a fluid solvent. In an embodiment of the present invention, the sedimentation step causes the undissolved contaminants to be subjected to a force that uniformly moves the undissolved contaminants in the direction of the force. The sedimentation force typically applied is gravity, but may also be centrifugal force, centripetal force, or some other force. The amount of force applied and the duration of sedimentation will depend on several parameters, including but not limited to: the particle size of the contaminant particles, the density of the contaminant particles, the density of the fluid or solution, and the viscosity of the fluid or solution. The following equation is the relationship between the above parameters and the sedimentation velocity, which is a measure of the sedimentation rate of the contaminant: v = 2gr 2 (ρ p -ρ f ) / 9η, where v is the sedimentation velocity, ρ p is the density of the pollutant particles, ρ f is the density of the fluid or solution, g is the acceleration due to the applied force (usually gravity), r is the radius of the contaminant particle, and η is the dynamic viscosity of the fluid or solution. Some of the key parameters that determine the viscosity of a solution are: the chemical composition of the fluid solvent, the MW of the polymer dissolved in the fluid solvent, the concentration of the polymer dissolved in the fluid solvent, the temperature of the fluid solvent solution, and the pressure of the fluid solvent solution.

[0272] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a temperature and pressure, wherein the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a pressure of about 200psig (1.38MPa) to about 9,000psig (62.05MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / fluid solvent solution at a pressure of about 400psig (2.76MPa) to about 2,600psig (17.93MPa).

[0273] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-butane solution at a pressure of about 4,000psig (27.58MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-butane solution at a pressure of about 4,200psig (28.96MPa) to about 7,000psig (48.26MPa). In an embodiment of the present invention, a process for purifying a recycled polymer comprises precipitating contaminants from a polyethylene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0274] In an embodiment of the present invention, a method for purifying a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution, wherein 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 a recycled polymer comprises settling contaminants from a polyethylene / n-butane solution, wherein 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%.

[0275] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-pentane solution at a pressure of about 800psig (5.52MPa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polyethylene / n-pentane solution at a pressure of about 900psig (6.21MPa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a process for purifying a recycled polymer comprises precipitating contaminants from a polyethylene / n-pentane solution at a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

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

[0277] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / fluid solvent solution at a temperature and pressure, wherein the polypropylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / n-butane solution at a pressure of about 350psig (2.41MPa) to about 4,000psig (27.57MPa). In an embodiment of the invention, the method for purifying the regenerated polymer comprises precipitating the contaminants from the 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 invention, the method for purifying the regenerated polymer comprises precipitating the contaminants from the polypropylene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

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

[0279] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / propane solution at a pressure of about 2,000psig (13.79MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polypropylene / propane solution at a pressure of about 3,000psig (20.68MPa) to about 6,000psig (41.37MPa). In an embodiment of the present invention, a process for purifying a recycled polymer comprises settling contaminants from a polypropylene / propane solution at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0280] In an embodiment of the present invention, the method for purifying the recycled polymer comprises settling contaminants from a polypropylene / propane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the recycled polymer comprises settling contaminants from a polypropylene / propane solution, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0281] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / fluid solvent solution at a temperature and pressure, wherein the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution at a pressure of about 1,000psig (6.89MPa) to about 9,000psig (62.05MPa). In an embodiment of the invention, the method for purifying the regenerated 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, the method for purifying the regenerated 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).

[0282] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution, wherein polystyrene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a polystyrene / n-butane solution, wherein polystyrene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 12%.

[0283] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure, wherein the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In an embodiment of the invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution and a solid medium at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0284] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0285] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises settling a first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising the settled polymer, at least one dissolved contaminant, and less of at least one suspended contaminant.

[0286] In embodiments of the invention, the temperature in the settling step is from about 110° C. to about 220° C. In embodiments of the invention, the pressure in the settling step is from about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0287] Mechanical filtration

[0288] For the purpose of the present invention and unless otherwise mentioned, the term "filtration" indicates "mechanical filtration" or "adsorption filtration", or the term includes both types of filtration. A typical filtration system includes a filter medium, a filter container, a filter inlet and a filter outlet. The filter medium includes filter particles contained in the filter container. The filter inlet is connected to the filter container fluid and conveys the filter feed flow into the filter container, and the filter outlet is connected to the filter system fluid and conveys the filtrate flow out of the filter container. The filtration system may include one or more filter media, filter containers, and filter inlets and filter outlets connected in series or in parallel. In addition, the filtration system can operate with radial flow or axial flow, or can operate with upward flow, downward flow or cross flow. A non-limiting example of a radial flow filter is a candle filter. In addition, the filtration can be a deep filtration type or a surface filtration type, and is based on a mechanical mode of action. A non-limiting example of a mechanical mode of action is size exclusion, in which suspended (dispersed) contaminants are retained by the filter medium and are therefore separated from the filter feed flow because the size of the suspended contaminants is larger than the pores of the filter medium. As described above, size exclusion is an inter-particle phenomenon.

[0289] The filter medium used in deep filtration includes an aggregate of filter particles, which can be homogeneous or heterogeneous. The filter particles can be evenly or unevenly distributed (e.g., layers of different filter particles) within the filter medium. The filter particles forming the filter medium do not have to have the same shape or size, and can be provided in a loose or interconnected form. For example, the filter medium can include filter particles, which can be loosely associated, or partially or completely bonded by a polymer adhesive or other means to form an integral structure.

[0290] In addition, filter particles can be provided in a variety of shapes and sizes. For example, but not limited to, filter particles can be provided in a simple form, such as powder, particles, fibers and beads. Filter particles can be provided in the shape of a sphere, a polyhedron, a cylinder and other symmetrical, asymmetrical and irregular shapes. In addition, filter particles can also form complex forms, such as nets, screens, grids, nonwoven materials, woven materials and adhesive blocks, which may or may not be formed by the above-mentioned simple form. Filter particles can vary in size, from intangible filter particles (for example, very fine powder) to tangible filter particles. In addition, in the filter particles used in any single filter system, the size of the filter particles does not have to be uniform. In fact, it may be desirable to provide filter particles with different sizes in a single filter.

[0291] In embodiments of the present invention, the size of the filter particle changes between about 0.1mm and about 10mm. In embodiments of the present invention, the size of the filter particle changes between about 10mm and about 8mm. In embodiments of the present invention, the size of the filter particle changes between about 100mm and about 5mm. In embodiments of the present invention, the size of the filter particle changes between about 1mm and about 4mm. In embodiments of the present invention, the size of the filter particle changes between about 10 μm and about 100 μm. For spherical and cylindrical particles (e.g., fibers, beads, etc.), the above-mentioned size refers to the diameter of the filter particle. For filter particles with significantly different shapes, the above-mentioned size refers to the maximum size (e.g., length, width or height).

[0292] Non-limiting examples of filter particles are silicon oxide (silicon dioxide), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, amorphous volcanic glass, regenerated glass, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, bleaching earth, bentonite, 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 silicon dioxide, activated alumina, silica gel, volcanic glass, bleaching earth, bentonite and mixtures thereof. In an embodiment of the present invention, the filter particles are selected from activated carbon, activated alumina, diatomaceous earth and mixtures thereof. In an embodiment of the present invention, the filter particles are selected from MOF, COF, ZIF, activated carbon, activated alumina and mixtures thereof. In an embodiment of the present invention, the filter particles are selected from diatomaceous earth, activated alumina and mixtures thereof.

[0293] The non-limiting example of the filter medium used in surface filtration is a thin layer of filter particles, porous ceramics, filter paper, filter cloth, plastic film, screen, nonwoven material, woven material, porous glass frit / sintered metal and perforated plate. In typical surface filtration, the retained pollutants form a filter cake on the top of the filter medium, and as the filtration is carried out, the thickness of the filter cake increases. Usually, after a certain filtration time, it is necessary to remove the filter cake because the filter cake provides an unsustainable pressure drop by mechanical action or recoil. In an embodiment of the present invention, the filter medium used in surface filtration is selected from a thin layer of diatomaceous earth particles deposited on a woven metal porous core (commonly referred to as a sock). The porous core supports the filter medium and allows the filtered feed stream to flow through. The non-limiting example of the core is a perforated tube and a screen sleeve.

[0294] Filter aids may be used in the filtration. Non-limiting examples of filter aids are diatomaceous earth (also known as kieselguhr), cellulose, and perlite. These filter aids may be used as a pre-coat for the filter media or added to the filter feed stream. In the latter case (also known as bulk feed), the filter aid increases the porosity of the filter cake formed on the filter media, thereby reducing the pressure drop across the filter cake during filtration.

[0295] At the end of its useful life, the filter can be removed from operation and replaced with a new filter, or regenerated. Non-limiting examples of regeneration are backflushing, thermal regeneration, and solvent regeneration.

[0296] 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 between about 1 mm and about 20 mm. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is between about 2 mm and about 10 mm. In an embodiment of the present invention, the thickness of the diatomaceous earth layer is between about 3 mm and about 5 mm.

[0297] The permeability of a filter medium is measured by passing a fluid through the filter medium and measuring the flow rate and pressure drop (as is well known to those skilled in the art). The unit of measurement is millidarcy (mD), and 1 mD is equivalent to 1 mL of a fluid with a viscosity of 1 mPa.s (1 cP) flowing through a cross-sectional area of ​​1 cm in 1 s at a pressure of 1 atm. 2 and a filter medium thickness of 1 cm. In embodiments of the present invention, the permeability of the diatomaceous earth medium is between about 30 mD and about 20,000 mD. In embodiments of the present invention, the permeability of the diatomaceous earth medium is between about 400 mD and about 8,000 mD. In embodiments of the present invention, the permeability of the diatomaceous earth medium is between about 1,000 mD and about 4,000 mD. In embodiments of the present invention, the permeability of the diatomaceous earth medium is between about 2,300 mD and about 3,400 mD.

[0298] In an embodiment of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 0.3 μm. In an embodiment of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 0.8 μm. In an embodiment of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 1 μm. In an embodiment of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 1.7 μm. In an embodiment of the present invention, the diatomaceous earth media retains suspended particles having a diameter greater than about 4 μm.

[0299] In an embodiment of the present invention, a candle filter comprises a thin diatomaceous earth media deposited on a woven metal core; wherein the thickness of the diatomaceous earth media is between about 2 mm and about 10 mm; wherein the permeability of the diatomaceous earth media is between about 2,300 mD and 3,400 mD; and wherein the diatomaceous earth media retains suspended particles having a diameter greater than about 1.7 μm.

[0300] In an embodiment of the present invention, the method for purifying the regenerated polymer includes filtering contaminants from a polyethylene / fluid solvent solution at a temperature and a pressure, wherein the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, the method for purifying the regenerated polymer 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 in the filtering step is about 110°C to about 220°C. In an embodiment of the present invention, the method for purifying the regenerated polymer includes filtering contaminants from a polyethylene / fluid solvent solution at a pressure of about 200psig (1.38MPa) to about 9,000psig (62.05MPa). In an embodiment of the present invention, the pressure in the filtering step is about 400psig (2.76MPa) to about 2,600psig (17.93MPa).

[0301] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4000psig (27.58MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4,200psig (28.96MPa) to about 7,000psig (48.26MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0302] In an embodiment of the present invention, the method for purifying the recycled polymer comprises filtering contaminants from a polyethylene / n-butane solution, wherein polyethylene is dissolved at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the recycled polymer comprises filtering contaminants from a polyethylene / n-butane solution, wherein polyethylene is dissolved at a mass percentage concentration of up to 20%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 12%.

[0303] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 800psig (5.52MPa) to about 4,000psig (27.58MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 900psig (6.21MPa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0304] In an embodiment of the present invention, the method for purifying the recycled polymer comprises filtering contaminants from a polyethylene / n-pentane solution, wherein polyethylene is dissolved at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the recycled polymer comprises filtering contaminants from a polyethylene / n-pentane solution, wherein polyethylene is dissolved at a mass percentage concentration of up to 20%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, polyethylene is dissolved at a mass percentage concentration of up to 12%.

[0305] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 350psig (2.41MPa) to about 4,000psig (27.57MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 1,000psig (6.89MPa) to about 3,500psig (24.13MPa). In an embodiment of the present invention, a method for purifying a recycled polymer comprises filtering contaminants from a polypropylene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0306] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution, wherein polypropylene is dissolved at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / n-butane solution, wherein polypropylene is dissolved at a mass percentage concentration of up to 20%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, polypropylene is dissolved at a mass percentage concentration of up to 12%.

[0307] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution at a pressure of about 2,000psig (13.79MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution at a pressure of about 3,000psig (20.68MPa) to about 6,000psig (41.37MPa). In an embodiment of the present invention, a process for purifying a recycled polymer comprises filtering contaminants from a polypropylene / propane solution at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0308] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution, wherein polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polypropylene / propane solution, wherein polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polypropylene is dissolved at a mass percent concentration of up to 12%.

[0309] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / fluid solvent solution at a temperature and a pressure, wherein the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 1,000psig (6.89MPa) to about 9,000psig (62.05MPa). In an embodiment of the invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In an embodiment of the invention, the method for purifying the regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution at a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0310] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution, wherein polystyrene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a polystyrene / n-butane solution, wherein polystyrene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, polystyrene is dissolved at a mass percent concentration of up to 12%.

[0311] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and a pressure, wherein the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 500psig (3.45MPa) to about 2,100psig (14.48MPa). In an embodiment of the invention, a method for purifying a regenerated 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 a regenerated 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).

[0312] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises filtering contaminants from a poly(dimethylsiloxane) / n-butane solution, wherein poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0313] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of a post-consumer recycled (PCR) polymer, a post-industrial recycled (PIR) polymer, and combinations thereof; and wherein the recycled polymer comprises contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants comprise at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) subjecting the recycled polymer to a precipitate at a temperature below the initial melting point of the recycled polymer and at a pressure between about atmospheric pressure and about 1,000 atm. leaching the alkylphenol, bisphenol, dioxin, PCB or phthalate from the regenerated polymer with an average removal efficiency in a plurality of leaching stages over a total residence time and a residence time in each of the leaching stages to produce a leached polymer comprising at least one of the alkylphenol, bisphenol, dioxin, PCB or phthalate, each having a concentration; and wherein the average removal efficiency is greater than about 55%; c) at a temperature of about 80° C. to about 280° C. and about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) a) extracting the leached polymer with a first fluid solvent having a normal boiling point of less than about 70° C. at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce an extracted polymer; 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 first solution comprising dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; e) 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 first solution comprising dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; and e) 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). sig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant and less of at least one suspended contaminant; and f) filtering the second solution by mechanical filtration at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtered polymer, at least one dissolved contaminant and even less of at least one suspended contaminant.

[0314] In an embodiment of the present invention, a method for purifying a recycled polymer comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer with an average removal efficiency of 1% to 20% at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm in a plurality of leaching stages using a leaching solvent at a total residence time and a residence time in each of the leaching stages. 118 and 2-ethylhexyl phthalate to produce a leached polymer comprising at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate, each having a certain concentration; wherein the average removal efficiency is greater than about 55%; 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 first fluid solvent, the second fluid solvent and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a leached polymer comprising at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118 and 2-ethylhexyl phthalate, each having a certain concentration; wherein the average removal efficiency is greater than about 55%; 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; f) settling the first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising the settled polymer, at least one dissolved contaminant and less of at least one suspended contaminant; g) filtering the 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 even less of at least one suspended contaminant.

[0315] Adsorption filtration

[0316] In an embodiment of the present invention, the method for purifying polyethylene is included in the temperature and pressure of the polymer still dissolved in the fluid solvent, and the contaminated polymer solution is contacted with a solid medium. The solid medium of the present invention (also referred to as adsorption medium or adsorption filter medium throughout the present invention) includes solid medium particles and is any solid material that removes at least some pollutants from the solution of the regenerated polyethylene dissolved in the fluid solvent of the present invention. Although it is not desired to be bound by any theory, the applicant believes that the solid medium removes pollutants by a variety of mechanisms. Non-limiting examples of possible mechanisms include adsorption, absorption, electrostatic, size exclusion, ion exclusion, ion exchange and other mechanisms that may be obvious to those of ordinary skill in the art. In addition, pigments and other pollutants common in regenerated polyethylene can be polar compounds or can have polar compounds on their surfaces, and can preferentially interact with solid media that can also be at least slightly polar. When using non-polar solvents (such as alkanes) as fluid solvents, polar-polar interactions are particularly advantageous.

[0317] In an embodiment of the present invention, the solid medium is selected from inorganic substances, carbon-based substances or mixtures thereof. Available examples of inorganic substances include silicon oxides, aluminum oxides, iron oxides, aluminum silicates, magnesium silicates, amorphous volcanic glass, silicon dioxide, silica gel, diatomaceous earth, sand, quartz, recycled glass, aluminum oxide, perlite, bleaching earth, bentonite and mixtures thereof. Available examples of carbon-based substances 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 medium particles are selected from the solid particles of the following substances: silicon oxide (silicon dioxide), silica gel, aluminum oxide (aluminum oxide), activated alumina, iron oxide, aluminum silicate, magnesium silicate, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, bleaching earth, bentonite, metal organic framework (MOF), covalent organic framework (COF), zeolite imidazolate framework (ZIF), cellulose and lignocellulose. In an embodiment of the present invention, the solid medium is selected from the group consisting of silica, activated alumina, silica gel, bleaching earth, bentonite and mixtures thereof. In an embodiment of the present invention, the solid medium is selected from the group consisting of activated carbon, activated alumina, diatomaceous earth and mixtures thereof. In an embodiment of the present invention, the solid medium is selected from the group consisting of MOF, COF, ZIF, activated carbon, activated alumina and mixtures thereof. In an embodiment of the present invention, the solid medium is selected from the group consisting of diatomaceous earth, activated alumina and mixtures thereof.

[0318] A non-limiting example of a physical mode of action is physical adsorption (also known as physical sorption), in which dissolved contaminants are adsorbed onto the outer or inner surface of the pores of the filter particles due to van der Waals forces and are thereby separated from the filter feed stream. Another non-limiting example of a physical mode of action is electrostatic adsorption, in which suspended contaminants are adsorbed onto the surface of the filter particles due to electrostatic attraction. Filter particles and filter media that remove contaminants primarily by adsorption are referred to as adsorption filter particles and adsorption filter media, respectively.

[0319] The adsorption filter medium is usually contained in a cylindrical filter container as a loose medium or a bonded block, and the adsorption filtration can be axial flow or radial flow. The cylindrical adsorption filter medium in the axial flow form has an aspect ratio defined as the ratio of the height to the diameter of the cylindrical adsorption filter medium. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 1. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 2. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 5. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 10. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 30. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 50. In an embodiment of the present invention, the aspect ratio of the cylindrical adsorption filter medium is equal to or greater than about 70.

[0320] In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 5 cm. In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 20 cm. In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 50 cm. In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 1 m. In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 1.5 m. In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 3 m. In an embodiment of the present invention, the height of the cylindrical adsorption filter medium is equal to or greater than about 6 m.

[0321] In an embodiment of the present invention, the adsorption filter medium is cylindrical; wherein the filter medium comprises loose adsorption filter particles; wherein the height of the cylindrical adsorption medium is about 122 cm; wherein the diameter of the cylindrical adsorption medium is about 1.7 cm; wherein the adsorption filter particles comprise activated alumina; and wherein the particle size of the adsorption filter particles is 7×14 mesh.

[0322] In an embodiment of the present invention, the solid medium is contacted with the polymer in the container for a specified amount of time while the solid medium is stirred. In an embodiment of the present invention, the solid medium is removed from a purer polymer solution via a solid-liquid separation step. Non-limiting examples of solid-liquid separation steps include filtration, decantation, centrifugation and sedimentation. In an embodiment of the present invention, the contaminated polymer solution is passed through a fixed bed of solid medium. In an embodiment of the present invention, the solid medium is replaced as needed to maintain the desired purity of the polymer. In an embodiment of the present invention, the solid medium is regenerated and reused in the purification step. In an embodiment of the present invention, the solid medium is regenerated during the backflush step by fluidizing the solid medium.

[0323] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / fluid solvent solution with a solid medium at a temperature and a pressure, wherein the polyethylene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / fluid solvent solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / fluid solvent solution with a solid medium at a temperature of about 110°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / fluid solvent solution with a solid medium at a pressure of about 200psig (1.38MPa) to about 9,000psig (62.05MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / fluid solvent solution with a solid medium at a pressure of about 400psig (2.76MPa) to about 2,600psig (17.93MPa).

[0324] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4000psig (27.58MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,200psig (28.96MPa) to about 7,000psig (48.26MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0325] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises contacting the polyethylene / n-butane solution with a solid medium, wherein the polyethylene is dissolved at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises contacting the polyethylene / n-butane solution with a solid medium, wherein the polyethylene is dissolved at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percentage concentration of up to 12%.

[0326] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 800psig (5.52MPa) to about 4,000psig (27.58MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 900psig (6.21MPa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0327] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polyethylene / n-pentane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polyethylene is dissolved at a mass percent concentration of up to 12%.

[0328] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying regenerated polypropylene comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 350psig (2.41MPa) to about 4,000psig (27.57MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 1,000psig (6.89MPa) to about 3,500psig (24.13MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / n-butane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0329] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises contacting the polypropylene / n-butane solution with a solid medium, wherein the polypropylene is dissolved at a mass percentage concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of at least 5%. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises contacting the polypropylene / n-butane solution with a solid medium, wherein the polypropylene is dissolved at a mass percentage concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percentage concentration of up to 12%.

[0330] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / propane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying regenerated polypropylene comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 2,000psig (13.79MPa) to about 8,000psig (55.16MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 3,000psig (20.68MPa) to about 6,000psig (41.37MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polypropylene / propane solution with a solid medium at a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0331] In an embodiment of the present invention, the method for purifying the regenerated polymer comprises contacting the polypropylene / propane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, the method for purifying the regenerated polymer comprises contacting the polypropylene / propane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0332] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / fluid solvent solution with a solid medium at a temperature and pressure, wherein the polystyrene remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 1,000psig (6.89MPa) to about 9,000psig (62.05MPa). In an embodiment of the invention, a method for purifying a regenerated 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 invention, a method for purifying a regenerated 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).

[0333] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium, wherein the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a polystyrene / n-butane solution with a solid medium, wherein the polystyrene is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 12%.

[0334] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / fluid solvent solution with a solid medium at a temperature and pressure, wherein the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 115°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 120°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 140°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 500psig (3.45MPa) to about 2,100psig (14.48MPa). In an embodiment of the invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In an embodiment of the invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0335] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium, wherein the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In an embodiment of the present invention, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In an embodiment of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

[0336] In an embodiment of the present invention, a method for purifying a recycled polymer is disclosed. The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from a post-consumer recycled (PCR) polymer, a post-industrial recycled (PIR) polymer, and a combination thereof; and wherein the recycled polymer contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm, for a total residence time and a residence time of each of the leaching stages. 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) 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 90°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) 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 90°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. 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 0° 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) settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising settled polymer, at least one dissolved contaminant, and less than at least one f) filtering the second solution by mechanical filtration at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution comprising a filtering polymer, at least one dissolved contaminant and even less of at least one suspended contaminant; and g) filtering the third solution by adsorptive filtration at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising a filtering polymer.

[0337] In an embodiment of the present invention, a method for purifying a regenerated polymer is disclosed.The method comprises: a) obtaining a recycled polymer; wherein the recycled polymer is selected from the group consisting of post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer contains contaminants, each of which has a certain concentration; and wherein the recycled polymer contaminants include at least one of 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate; b) surface washing the recycled polymer in a non-densified state to produce a surface washed polymer; wherein the surface washing results in a reduction of loosely bound surface contaminants by greater than about 80%; c) leaching the 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate from the recycled polymer with an average removal efficiency at a temperature below the initial melting point of the recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm in a plurality of leaching stages using a leaching solvent within a total residence time and a residence time in each of the leaching stages to produce a recycled polymer containing 4-tert-amylphenol, bisphenol A, OCDD, PCB 118, and 2-ethylhexyl phthalate. 118 and 2-ethylhexyl phthalate, each having a certain concentration; wherein the average removal efficiency is greater than about 55%; 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 first fluid solvent, the second fluid solvent and a mixture thereof at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising a dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant; f) at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solution comprising a dissolved polymer, at least one dissolved contaminant and at least one suspended contaminant. 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 comprising the filtered polymer, at least one dissolved contaminant and even less of at least one suspended contaminant; and h) 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) by contacting the third solution with one or more solid media to produce a fourth solution comprising the twice filtered polymer.

[0338] In an embodiment of the invention, the temperature in the extraction, dissolution, settling and filtration steps is about 110° C. to about 220° C. In an embodiment of the invention, the pressure in the dissolution, settling and filtration steps is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0339] Separation

[0340] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating a purer polymer from a fluid solvent at a temperature and pressure, wherein the polymer precipitates from the solution and is no longer dissolved in the fluid solvent. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by reducing the pressure at a fixed temperature. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by reducing the temperature at a fixed pressure. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by increasing the temperature at a fixed pressure. In an embodiment of the present invention, precipitating a purer polymer from a fluid solvent is accomplished by reducing both the temperature and the pressure. By controlling the temperature and pressure, the solvent may be partially or completely converted from a liquid to a gas phase. In an embodiment of the present invention, by controlling the temperature and pressure of the solvent during the separation step, the precipitated polymer is separated from the fluid solvent in the case where the fluid solvent is not completely converted to 100% of the gas phase. The separation of the precipitated purer polymer is accomplished by any method of liquid-liquid or liquid-solid separation. Non-limiting examples of liquid-liquid or liquid-solid separation include filtration, decantation, centrifugation, and sedimentation.

[0341] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / fluid solvent solution at a temperature and pressure, wherein the polyethylene is precipitated from the solution. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 0°C to about 280°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 50°C to about 175°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 0psig (0MPa) to about 4,000psig (27.58MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / n-butane solution at a pressure of about 50psig (0.34MPa) to about 2,000psig (13.79MPa). In an embodiment of the present invention, a process for purifying a 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).

[0342] In an embodiment of the present invention, a method for purifying a regenerated polymer 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 a regenerated polymer 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 a regenerated polymer 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 a regenerated polymer comprises separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 0psig (0MPa) to about 2,000psig (13.79MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 50psig (0.34MPa) to about 1,500psig (10.34MPa). In an embodiment of the present invention, a process for purifying a recycled polymer comprises separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0343] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / fluid solvent solution at a temperature and pressure, wherein the polypropylene is precipitated from the solution. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 100°C to about 200°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 0psig (0MPa) to about 2,000psig (13.79MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / n-butane solution at a pressure of about 50psig (0.34MPa) to about 1,500psig (10.34MPa). In an embodiment of the present invention, a process for purifying a 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).

[0344] In an embodiment of the present invention, a method for purifying a regenerated polymer 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 a regenerated polymer 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 a regenerated polymer 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 a regenerated polymer comprises separating polypropylene from a polypropylene / propane solution at a pressure of about 0psig (0MPa) to about 6,000psig (41.37MPa). In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene / propane solution at a pressure of about 50psig (0.34MPa) to about 3,000psig (20.68MPa). In an embodiment of the present invention, a process for purifying a recycled polymer comprises separating polypropylene from a polypropylene / propane solution at a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0345] In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene / fluid solvent solution at a temperature and pressure, wherein the polystyrene is precipitated from the solution. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 100°C to about 200°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In an embodiment of the present invention, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene / n-butane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In an embodiment of the invention, the method for purifying the 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, the method for purifying the 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).

[0346] In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure wherein the poly(dimethylsiloxane) is precipitated from the solution. In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 0°C to about 220°C. In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 200°C. In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 180°C. In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 0 psig (0 MPa) to about 1,500 psig (10.34 MPa). In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 50 psig (0.34 MPa) to about 1,000 psig (6.89 MPa). In an embodiment of the invention, a method for purifying a regenerated polymer comprises separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at a pressure of about 75 psig (0.52 MPa) to about 500 psig (3.45 MPa).

[0347] In an embodiment of the invention, the filtering 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 about 2,000 psig (13.79 MPa).

[0348] IX. Test Methods

[0349] The test method described herein is used to measure the effectiveness of various polymer purification methods. Specifically, the method demonstrates the effectiveness of a given purification method in improving color and translucency / transparency (i.e., making the color and opacity of the recycled polymer closer to the color and opacity of the uncolored original polymer), reducing or eliminating elemental contamination (i.e., removing heavy metals), reducing or eliminating non-combustible contaminants (i.e., inorganic fillers), reducing or eliminating volatile compounds (especially volatile compounds that contribute to the malodor of the recycled polymer), and reducing or eliminating polymer contamination (i.e., polyethylene contamination in polypropylene).

[0350] Color and opacity measurements

[0351] The color and opacity / translucency of a polymer are important parameters for determining whether a polymer can achieve the desired visual aesthetic of an article made from the polymer. Recycled polymers, especially PCR polymers, are often 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 method for purifying a polymer.

[0352] Prior to color measurement, a sample of one of the polymer powders or pellets was compression molded into a 30 mm wide × 30 mm long × 1 mm thick square specimen (with rounded corners). Using clean, unused aluminum foil as a contact isolation layer between stainless steel plates, the powder sample was first densified at room temperature (about 20-23° C.) by cold pressing the powder into a sheet. Then about 0.85 g of cold pressed powder or pellets was pressed into a specimen on a C-type Carver Press (Carver, Inc., Wabash, IN 46992-0554 USA) preheated to 200° C. using an aluminum platen, an unused aluminum foil isolation layer, and a stainless steel shim with a cavity corresponding to the aforementioned size of the square specimen. The sample was heated for 5 min before applying pressure. After 5 min, the pressed product was then compressed for at least 5 seconds using a hydraulic pressure of at least 2 tons (1.81 metric tons) and then released. The molded stack was then removed and placed between two thick flat metal heat sinks for cooling. The aluminum foil contact release layer was then peeled off from the sample and discarded. The burrs around the sample on at least one side were peeled off to the edge of the die, and the sample was then pushed through the form. Each specimen was visually evaluated for void / bubble defects, and only samples without defects in the color measurement area (0.7" (17.78 mm) minimum diameter) were used for color measurement.

[0353] The color of each sample is characterized using the International Commission on Illumination (CIE) L*, a*, b* three-dimensional color space. Dimension L* is a measure of sample brightness, where L*=0 corresponds to the darkest black sample, and L*=100 corresponds to the brightest white sample. Dimension a* is a measure of the red or green color of the sample, where a positive a* corresponds to red, and a negative a* corresponds to green. Dimension b* is a measure of the blue or yellow color of the sample, where a positive b* corresponds to yellow, and a negative b* corresponds to blue. The L*a*b* values ​​of each 30 mm wide × 30 mm long × 1 mm thick square sample sample were measured on a HunterLab LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-5280, USA). The spectrophotometer was configured with D65 as the standard illuminant, an observation angle of 10°, an area diameter viewing angle of 1.75" (44.45 mm), and a port diameter of 0.7" (17.78 mm).

[0354] The opacity of each sample was determined using the aforementioned Hunter Lab spectrophotometer using the contrast ratio opacity mode, which is a measure of how much light is transmitted through the sample (i.e., a measure of the translucency of the sample). Two measurements were taken to determine the opacity of each sample. One measurement was made with a white backing as the background to measure the brightness value Y of the sample. 白色背衬 , and once with the black backing as the background measure the brightness value Y of the sample 黑色背衬 . The opacity is then calculated from the brightness value using the following equation:

[0355]

[0356] Elemental analysis

[0357] Many recycled polymers have unacceptably high levels of heavy metal contamination. The presence of heavy metals, such as lead, mercury, cadmium, and chromium, may 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 when determining the effectiveness of a method for purifying a polymer.

[0358] Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Test solutions were prepared at n=2 to n=6, depending on sample availability, by mixing approximately 0.25 g of sample with 4 mL of concentrated nitric acid and 1 mL of concentrated hydrofluoric acid (HF). The samples were digested using an Ultrawave microwave digestion protocol consisting of a 20 min heating to 125 ° C, a 10 min heating to 250 ° C, and a 20 min hold at 250 ° C. The digested samples were cooled to room temperature. After adding 0.25 mL of 100 ppm Ge and Rh as internal standards, the digested samples were diluted to 50 mL. In order to evaluate the accuracy of the measurements, pre-digested spikes were prepared by doping virgin polymers. Samples doped with virgin polymers were weighed by the same process described above, and doped with appropriate amounts of a single element of interest, including Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb. Spikes were prepared at two different levels: "low-level spikes" and "high-level spikes". Each spike was prepared in triplicate. In addition to the virgin polymer, the blank was spiked to confirm that no errors occurred during the pipetting process and to track recycling throughout the process. The blank doped samples were also prepared in triplicate at two different levels and processed in the same manner as the doped virgin polymer and test samples. A 9-point calibration curve was prepared by preparing solutions containing Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd and Pb at 0.05ppb, 0.1ppb, 0.5ppb, 1ppb, 5ppb, 10ppb, 50ppb, 100ppb and 500ppb. All calibration standards were prepared by diluting pure standard reference solutions and 0.25mL of 100ppm Ge and Rh as internal standards using 4mL concentrated nitric acid and 1mL concentrated HF. The prepared standards, test samples and doped test samples were analyzed using Agilent's 8800ICP-QQQMS and optimized according to the manufacturer's recommendations. The m / z of each analyte monitored and the collision cell gas used for the analysis were as follows: Na, 23 m / z, H2; Al, 27 m / z, H2; Ca, 40 m / z, H2; Ti, 48 m / z, H2; Cr, 52 m / z, He; Fe, 56 m / z, H2; Ni, 60 m / z; no gas; Cu, 65 m / z, no gas; Zn, 64 m / z, He; Cd, 112 m / z; H2; Pb, total 206 ≥ 206, 207 ≥ 207, 208 ≥ 208 m / z, no gas; Ge, 72 m / z, all modes; Rh, 103 m / z, all modes. Ge was used as an internal standard for all elements less than 103 m / z, and Rh was used for all elements greater than 103 m / z.

[0359] Residual ash content

[0360] Many recycled polymers contain various fillers, such as calcium carbonate, talc, and glass fibers. Although useful for the original application of the recycled polymer, these fillers change the physical properties of the polymer in ways that are undesirable for the next application of the recycled polymer. Therefore, measuring the amount of filler is important when determining the effectiveness of a method for purifying a polymer.

[0361] Thermogravimetric analysis (TGA) was performed to quantify the amount of non-combustible material (sometimes referred to as ash content) in the sample. Approximately 5 mg to 15 mg of sample was loaded onto a platinum sample pan and heated to 700° C. in an air atmosphere at a rate of 20° C. / min in a TA Instruments Q500 TGA instrument. The sample was kept isothermally at 700° C. for 10 minutes. After the isothermal hold, the residue mass percentage was measured at 700° C.

[0362] Odor analysis

[0363] Odor sensory analysis was performed by placing approximately 3 g of each sample in a 20 mL glass vial and equilibrating the sample at room temperature for at least 30 min. After equilibration, each vial was opened and the headspace was bunny sniffed by a trained grader to determine odor intensity and descriptor characteristics. Odor intensity was graded according to the following scale: 5 = very strong; 4 = strong; 3 = moderate; 2 = weak to moderate; 1 = weak; and 0 = no odor.

[0364] Polymer Contamination Analysis

[0365] Many regenerated polymers, particularly regenerated polymers derived from mixed stream sources, may contain undesirable polymer contaminants. Without wishing to be bound by any theory, polymer contamination (e.g., polyethylene contamination in polypropylene) may affect the physical properties of the polymer due to the presence of heterogeneous phases and the resulting weak interface. In addition, polymer contamination may also increase the opacity of the polymer and have an impact on color. Therefore, when determining the effectiveness of the method for purifying polymers, it is important to measure the amount of polymer contamination.

[0366] Differential Scanning Calorimetry (DSC) was used to evaluate semi-crystalline polymer contamination. For example, to measure the amount of polyethylene contamination in polypropylene, 2 wt%, 4 wt%, 6 wt%, 8 wt% and 10 wt% of A set of five polypropylene / polyethylene blends were prepared with HB5502F HDPE (Formosa Plastics Corporation, USA) in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, BV). Approximately 5 mg to 15 mg of each sample was sealed in an aluminum DSC pan and analyzed on a TA Instruments Q2000 DSC using the following method:

[0367] 1. Equilibrate at 30.00℃

[0368] 2. Ramp up to 200.00℃ at 20.00℃ / min

[0369] 3. Mark the end of cycle 0

[0370] 4. Ramp up to 30.00℃ at 20.00℃ / min

[0371] 5. Mark the end of cycle 1

[0372] 6. Ramp up to 200.00℃ at 20.00℃ / min

[0373] 7. Marking the end of cycle 2

[0374] 8. Ramp up to 30.00℃ at 20.00℃ / min

[0375] 9. Marking the end of cycle 3

[0376] 10. Ramp up to 200.00℃ at 5.00℃ / min

[0377] 11. Marking the end of cycle 4

[0378] The melting enthalpy of the HDPE peak around 128°C was calculated using a 5.00°C / min DSC thermogram for each sample with known HDPE content. Figure 2 As shown, a linear calibration curve was established by plotting the melting enthalpy versus known HDPE concentration (in wt %).

[0379] The same above-mentioned DSC equipment and method are used to analyze the sample with unknown PE content. The above-mentioned calibration curve is used to calculate the PE content. The specific HDPE used to generate the calibration curve is more likely to have different degrees of crystallinity than the polyethylene (or polyethylene blend) pollution that may exist in the recycled polymer sample. Crystallinity can independently affect the measured melting enthalpy of polyethylene, and thus affect the obtained calculation result of polyethylene content. However, the DSC test method described herein is intended to be a relative measure of the effectiveness of different methods for purifying polymers as a comparison, and is not meant to be a strict quantitative measurement of polyethylene content in polymer blends. Although the above-mentioned method describes the measurement of polyethylene pollution in polypropylene, the method can be applied to the measurement of peaks in other semi-crystalline polymers and DSC thermograms using different temperature ranges. In addition, alternative methods such as nuclear magnetic resonance (NMR) spectroscopy can also be used to measure the amount of semi-crystalline and amorphous polymer pollution in the sample.

[0380] Analytical determination of chemical contaminants

[0381] For pesticides: EN 15662:2018-07 Modular QuEChERS method was applied. For alkylphenol ethoxylates, alkylphenols and bisphenols, the following technique was applied: the samples were cut, homogenized and weighed; then, an internal standard (deuterated bisphenol A) was added, the samples were then extracted with hexane at room temperature, derivatized with the addition of MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide), and the contaminant levels were determined by GC-MSD. For dioxins, furans and PCBs: ISO / IEC17025:2005 method was applied. The sample was cut into small pieces, 13C / 12C labeled PCDD / F internal standard was added to an aliquot of the sample material, extracted and matrix destroyed with hexane and H2SO4 for 1 hour, re-extracted with hexane (3 times for 30 min), multi-step chromatographic cleaning was applied, 13C / 12C labeled PCDD / F recovery standard was added to the measurement solution, and quantification was performed by internal labeled PCDD / F standard (isotope dilution technique and internal standard technique). For organotin: The method follows the EDANA protocol for organotin compounds in absorbent hygiene products and their constituent raw materials (WSP 351). More specifically, the sample was extracted with ethanol containing sodium diethyldithiocarbamate solution, alkylated with sodium tetraethylborate, and transferred to the organic phase by extraction with hexane. Then, the tetrasubstituted organotin compounds were separated by using capillary gas chromatography, demonstrated with AED or MS as detector. GC-ICP-MS was used as the detector system for organometallic analysis. For phthalates: The sample was cut, homogenized and weighed. Then an internal standard was used and extracted with hexane at room temperature. The extracted phthalates were then identified and quantified by GC-MSD. For PAH: The sample was cut, homogenized and weighed. Then, an internal standard of deuterated PAH was added and the sample was extracted with hexane. The extracted PAH was purified with silica gel, concentrated and then characterized by GC-MSD.

[0382] Amount of loosely bound surface contaminants

[0383] The amount of loosely bound surface contamination is determined by the following method: About 20 g of plastic is added to a 1,000 mL round bottom flask. About 300 mL of distilled water is added to the 1,000 mL round bottom flask. The round bottom flask is capped and then shaken vigorously for about 60 seconds. The water is decanted from the flask. About 600 mL of additional distilled water is added to the 1,000 mL flask and then immediately decanted, leaving the original regenerated polymer with a small amount of water. The regenerated polymer is removed from the round bottom and allowed to dry overnight in a convection oven at 60°C. The % change in mass of the plastic is the am...

Claims

1. A method for purifying a regenerated polymer, the method comprising: a. obtaining the recycled polymer; wherein the recycled polymer is selected from post-consumer recycled (PCR) polymers, post-industrial recycled (PIR) polymers, and combinations thereof; and wherein the recycled polymer comprises contaminants, each contaminant having a concentration; and wherein the recycled polymer contaminants comprise at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, polychlorinated biphenyls (PCBs), metals, organotins, phthalates, or polycyclic aromatic hydrocarbons (PAHs); b. leaching said pesticide, alkylphenol ethoxylate, alkylphenol, bisphenol, dioxin and dioxin-like compounds, PCB, metal, organotin, phthalate and PAH from said recycled polymer with an average removal efficiency using a leaching solvent in a plurality of leaching stages at a temperature below the initial melting point of said recycled polymer and a pressure between about atmospheric pressure and about 1,000 atm over a total residence time and a residence time in each of said leaching stages to produce a leached polymer comprising at least one of pesticide, alkylphenol ethoxylate, alkylphenol, bisphenol, dioxin and dioxin-like compounds, PCB, metal, organotin, phthalate and PAH, each having a concentration; and wherein said average removal efficiency of said leached polymer is greater than about 55%; 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 extraction 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 first solution comprising a dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; e. settling the first solution at a temperature of about 90° C. to about 280° C. and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution comprising a settled polymer, at least one dissolved contaminant, and less of 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 a filtration polymer, at least one dissolved contaminant, and even less of the at least one suspended contaminant; g. filtering the third solution by adsorption filtration at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a fourth solution comprising a filtration polymer; as well as h. separating the filtered polymer from the fourth solution to produce a purer polymer having an average removal efficiency; wherein the purer polymer comprises at least one of pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins and dioxin-like compounds, PCBs, metals, organotins, phthalates, or PAHs, each having a certain concentration; wherein the second fluid solvent has the same chemical composition or a different chemical composition as the first fluid solvent; and wherein the average removal efficiency of the purer polymer is greater than about 75%.

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

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

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

5. The method according to any one of claims 1 to 4, wherein the regenerated polymer has a thickness greater than about 1 mm -1 The average surface area to volume ratio.

6. The method of any one of the preceding claims, wherein the total residence time of the leaching step is less than about 360 min.

7. The method according to any one of the preceding claims, wherein the leaching solvent is an organic solvent or a mixture of organic solvents, preferably wherein the leaching solvent is at least one of DME, diethyl ether, MEK, ethyl acetate, THF, acetone, methanol, CO2 or a mixture thereof.

8. The method of any of the preceding claims, wherein the regenerated polymer is surface washed in a non-densified state in one or more surface washing steps prior to the leaching step; wherein the one or more surface washing steps result in a reduction of loosely bound surface contamination by greater than about 80%; and wherein the regenerated polymer has a thickness greater than about 1 mm prior to the surface washing steps. -1 The average surface area to volume ratio.

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

10. The method of any of the preceding claims, wherein the filtration 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 about 2,000 psig (13.79 MPa).

11. The method according to any one of the preceding claims, wherein the extraction polymer is dissolved in the fluid solvent or fluid solvent mixture in a concentration of at least 0.5% by mass.

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

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

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

15. The method according to any one of the preceding claims, wherein the fluid solvent has a normal boiling point of less than about 0°C and greater than about -45°C and a normal enthalpy change of vaporization of less than about +25 kJ / mol, preferably wherein the fluid solvent is at least one of an olefin, an aliphatic hydrocarbon, or a mixture thereof, more preferably wherein the aliphatic hydrocarbon is at least one of a C1-C6 aliphatic hydrocarbon or a mixture thereof.

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