Method for purifying recycled polymers

Abstract

A method for purifying a regenerated polymer into a higher-purity polymer is disclosed. In embodiments of the present invention, the method includes obtaining a regenerated polymer, leaching various contaminants using a leaching solvent to produce an leached polymer, extracting the leached polymer using a first fluid solvent to produce an extracted polymer, and then dissolving the extracted polymer in a solvent to produce a first solution containing the dissolved polymer. The first solution is precipitated and then filtered. A higher-purity polymer is separated from the obtained solution.

Description

[Technical Field]

[0001] The present invention relates to a method for purifying contaminated recycled polymers to higher purity polymers by generally combining an immersion leaching step and a purification step, using a leaching solvent and a pressurized solvent. More specifically, the recycled polymer is selected from the group consisting of post-consumer reclaimed (PCR) polymers, post-industrial reclaimed (PIR) polymers, and combinations thereof. The higher purity polymer is colorless or transparent, odorless, and virtually indistinguishable from a non-recycled polymer. The present invention is particularly useful for the purification of polyolefins such as polyethylene and polypropylene. [Background technology]

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

[0003] The widespread use of synthetic polymers generates millions of tons of plastic waste every year. While the majority of plastic waste is disposed of in landfills through municipal solid waste programs, a significant portion of it remains in the environment as litter, potentially detracting from aesthetics and harming ecosystems. Plastic waste often flows into river systems and eventually into the ocean.

[0004] To mitigate the problems associated with the widespread use of plastics, plastic recycling has emerged as a solution. By recovering and reusing plastics, waste is avoided from landfills, the demand for newly manufactured non-recycled plastics from fossil resources is reduced, and as a result, GHG emissions are lowered. In developed countries such as the United States and the European Union, plastic recycling rates are increasing due to growing awareness among consumers, businesses, and manufacturers. The majority of recycled materials, including plastics, are mixed into a single stream, which is then collected and processed at a material recovery facility (MRF). At the MRF, the materials are sorted, washed, and packaged for resale. The plastics may be separated into individual materials such as high-density polyethylene (HDPE) or poly(ethylene terephthalate) (PET), or they may be mixed into a stream with other common plastics (e.g., polypropylene (PP), low-density polyethylene (LDPE), liner low-density polyethylene (LLDPE), poly(vinyl chloride) (PVC), polystyrene (PS), polycarbonate (PC), and polyamide (PA)). The single or mixed streams can then be further separated, washed, and reprocessed at a plastics recovery facility (PRF) to produce pellets suitable for reuse in plastic processing, such as blow molding, morph extrusion, injection molding, and film manufacturing.

[0005] Recycled plastics are sorted and each is sent through multiple, overwhelmingly uniform streams, after which they are washed with aqueous and / or caustic solutions. However, the final reprocessed pellets often remain highly contaminated with undesirable waste impurities, such as spoiled food residues and residual flavorings. In addition, recycled plastic pellets, with the exception of those obtained from recycled beverage containers, are heavily colored with mixtures of dyes and pigments commonly used to color plastic articles. While some applications are less critical regarding color and contamination (e.g., black plastic containers for paint, hidden automotive parts), most applications require colorless pellets. The need for high-quality, "almost non-recycled" recycled resins is particularly important in applications that come into contact with food and pharmaceuticals, such as food packaging. In addition to contamination by impurities and mixed colorants, many recycled resin products often have heterogeneous chemical compositions and may contain significant amounts of polymer inclusions (e.g., polyethylene (PE) contamination in recycled PP, or vice versa).

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

[0007] Film is a special case of recycled plastic, primarily composed of polyolefins. Film recycling presents its own set of unresolved challenges. The supply chain for recycled film can be divided into two general categories: 1) pre-consumer recycled film, which includes both PIR film (film generated from in-house waste that can be reused in the same process that produced the recycled film) and PIR film (film generated from in-house waste that is not used in the same process that produced the recycled film); and 2) PCR film, which includes post-market recycled film (e.g., storefront shrink wrap, pallet wrap, wholesale bags, furniture wrap, agricultural film, etc.) which is commercially used but not directly used by household consumers, and post-household recycled film (e.g., retail bags, retail food packaging, overwrap for diapers and hygiene products, garbage bags, etc.) which is commercially used directly by household consumers. PIR film waste for recycling is collected plant by plant for controlled end markets and may or may not involve (or require) significant cleaning before recycling. PCR films are collected at the point of sale and transported to various film-specific PRFs for various cleaning processes and distribution to the end market. In the United States, film after household use is primarily collected through store collection programs where end consumers return the film to collection bins at local stores. Film-based PRFs collect film waste, sort and clean it, and then send it to the end market. The use of recycled film materials is very limited due to contamination. Film is more susceptible to contamination than other forms due to its high surface area-to-volume ratio, which increases the potential for external contamination. Currently, most recycled film-based plastics are downcycled to size-limited markets such as plastic wood, rather than in a circular economy. With the increasing collection of film-based waste, the need for an end market beyond plastic wood is essential. Ideally, film-based waste should ultimately be reused in film-based applications, ensuring continuous circularity.

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

[0009] While contamination is a problem for all end-market applications, the requirements for demanding applications are even more stringent, particularly for certain chemical contaminants. Relevant chemical contaminants are classified into various chemical categories depending on their chemical structure. Non-exclusive examples of contaminants in these chemical categories include heavy metals, pesticides, dioxins, furans, polychlorinated biphenyls (PCBs), phthalates, polycyclic aromatic hydrocarbons (PAHs), organotin, bisphenols, isothiazolins, glyphosate, alkylphenols, alkylphenol ethoxylates, aromatic amines, and flame retardants. Furthermore, the target levels for these contaminants can be extremely low. For example, target levels may be parts per million (ppm), parts per billion (ppb), and parts per trillion (ppt), while the initial level of contamination in plastics can be 1,000 times the target level. That is, it is often necessary to reduce chemical contamination to 1,000 times its original level.

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

[0011] U.S. Patent No. 10,022,725 discloses a mechanical recycling method for cleaning linear low-density polyethylene (LLDPE) / LDPE film for use in recycling. Patent No. 725 further discloses a shredding step, a first washing step, a second size reduction step including wet grinding, one or more friction washing steps in which hot water is used in at least one step, one or more drying steps, and a compression step. While this method may be very effective for removing some loosely bound surface contamination, it is not effective for removing bulk contamination due to the extremely low solubility of bulk contaminants in aqueous washing media and / or the limited diffusivity of bulk contaminants into plastics.

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

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

[0014] U.S. Patent No. 6,555,588 describes a method for producing a polypropylene blend from a plastic mixture containing other polymers. The '588 patent describes extracting contaminants from the polymer at a temperature lower than the polymer's dissolution temperature in a selected solvent (e.g., hexane) over a predetermined residence time. The '588 patent further describes raising the temperature of the solvent (or a second solvent) to dissolve the polymer prior to filtration. The '588 patent also further describes precipitating the polypropylene from the solution using shear or flow. The polypropylene blend described in the '588 patent contained up to 5.6 wt% polyethylene contamination.

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

[0016] U.S. Patent No. 5,198,471 describes a method of separating polymers from a physically mixed solid mixture (e.g., waste plastic) containing a plurality of polymers using a solvent at a first low temperature to form a first single-phase solution and the remaining solid components. The '471 patent further describes heating this solvent to a higher temperature to dissolve additional polymers that were not solubilized at the first lower temperature. The '471 patent describes filtering the insoluble polymer components.

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

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

[0019] U.S. Patent No. 5,368,796 discloses a method for surface cleaning a polyethylene film. Patent No. 796 further discloses a process of shredding, a first surface cleaning step (using a boiling solvent at a temperature below the melting point of polyethylene and at or near the ambient pressure, with vigorous mechanical stirring for 30 minutes to rub off ink), a second surface cleaning step (using a fresh solvent below the melting point of polyethylene, with vigorous mechanical stirring for 30 minutes), a third surface cleaning step (using a solvent below the melting point of polyethylene, with vigorous mechanical stirring for 30-60 minutes to perform defoliation), and a melt densification step. If necessary, the method may include a water rinsing step to remove surface contaminants before the solvent treatment. Patent No. 796 further discloses that solvent cleaning achieves extraction in which the solvent does not dissolve the polymer. However, small amounts, typically less than 1% by weight of wax, may be removed. The solvent cleaning and extraction steps are further disclosed as being performed at the boiling point of a solvent selected so as to be below the softening point of polyethylene to avoid aggregation. The methods described above focus on removing surface-printed ink and do not address the removal of bulk permeable contaminants as mentioned earlier.

[0020] U.S. Patent Application No. 2009 / 0178693 discloses a method for refining plastics. Patent Application No. 693 further discloses a multi-step process including granulation for forming plastic chips, surface cleaning with supercritical CO2, surface cleaning and extraction with a high-boiling point solvent or solvent mixture (such as limonene and ethylene lactate), final surface cleaning with supercritical CO2 to remove the high-boiling point solvent from the surface, and defloration. Furthermore, it is disclosed that the plastic chip material is stirred with the solvent and that the shape of the chips is maintained. It is also disclosed that the recovered material remains as chips, meaning that the process is completed at a temperature below the primary melting point of the plastic.

[0021] U.S. Patent No. 9,834,621 discloses a method for purifying polypropylene. Patent No. 621 describes a method for producing extracted recycled polypropylene by contacting recycled polypropylene with a first fluid solvent having a standard boiling point of less than 70°C at a temperature of about 80°C to about 280°C and a pressure of about 10 atm to about 544 atm; dissolving the extracted recycled polypropylene in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof at a temperature of about 90°C to about 280°C and a pressure of about 14 atm to about 544 atm to produce a first solution containing polypropylene, at least one dissolved contaminant, and at least one suspended contaminant; and dissolving the first solution at a temperature of about 90°C to about 280°C and Further disclosures include: precipitating under a pressure of approximately 14 atm to approximately 544 atm to produce a second solution containing polypropylene, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant; filtering the second solution at a temperature of approximately 90°C to approximately 280°C and a pressure of approximately 14 atm to approximately 544 atm to produce a third solution containing higher purity polypropylene, at least one dissolved contaminant, and an even smaller amount of at least one suspended contaminant; and separating the higher purity polypropylene from the third solution, wherein the second fluid solvent has the same or a different chemical composition as the first fluid solvent. The above method is very suitable for decontamination. However, the ability to dissolve, precipitate, and filter plastics is extremely difficult and may be unsuitable or impractical for high molecular weight (MW) plastics such as those used in films and blow-molded containers. Furthermore, the above method does not mention removing surface contamination before extraction and dissolution, and therefore increases the burden of such disclosed processes, particularly filtration.

[0022] In summary, known solvent-based methods for purifying contaminated plastics, as described above, do not adequately and efficiently address the problem of removing both surface and bulk contaminants from plastics to enable their use in demanding applications, particularly in film and rigid applications involving high-MW plastics, and therefore do not produce polymers that are "virtually non-recycled." Furthermore, the above methods often result in co-dissolution with other polymers, and thus cross-contamination. When adsorbents are used, filtration and / or centrifugation steps are often employed to remove used adsorbents from the solution. In addition, separation processes for solvent removal, such as heating, vacuum evaporation, and / or precipitation using precipitants, are used to produce polymers free of residual solvents. [Prior art documents] [Patent Documents]

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

[0024] [Non-Patent Document 1] SMAl-Salem, P. et al., Waste Management, 29(10)(2009), 2625-2643. [Overview of the project] [Problems that the invention aims to solve]

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

[0026] Embodiments of the present invention disclose a method for purifying a regenerated polymer. The method comprises: a) obtaining a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; and b) removing alkylphenols, bisphenols, dioxins, PCBs, or phthalates from the regenerated polymer by mean removal. a) The process involves leaching the regenerated polymer in multiple leaching stages using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and at a pressure near atmospheric pressure to about 1,000 atm, over a total residence time and the residence time of each leaching stage, to produce leached polymers containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, each with a concentration greater than 55%, and a) the leached polymers at a temperature of about 90°C to about 280°C and about 200 psig (1.38 MP). a) Dissolve the polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, under a pressure of approximately 9,000 psig (62.05 MPa) to produce a first solution containing the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; and d) Precipitate the first solution at a temperature of approximately 90°C to approximately 280°C and a pressure of approximately 200 psig (1.38 MPa) to approximately 9,000 psig (62.05 MPa) to obtain the precipitated polymer, at least one dissolved contaminant, and a smaller amount a) producing a second solution containing 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 containing the filtered polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant, and f) filtering the third 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).The process includes: (a) filtering the polymer twice by adsorption filtration under a pressure of 0.5 MPa to produce a fourth solution containing the filtered polymer; and (b) separating the filtered polymer from the fourth solution to produce a higher purity polymer, wherein the second fluid solvent has the same or a different chemical composition as the first fluid solvent.

[0027] Embodiments of the present invention disclose a method for purifying a regenerated polymer. The method comprises: a) obtaining a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate; and b) surface-washing the regenerated polymer in a non-densified state to obtain the surface-washed polymer. The process involves generating a polymer, and surface cleaning results in a reduction of over 80% of loosely bound surface contamination. The process involves generating and, from the regenerated polymer, leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate in multiple leaching stages using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to approximately 1,000 atm, over the total residence time and the residence time of each leaching stage, with an average removal efficiency, thereby removing 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate. The method involves producing an leached polymer containing at least one of ethylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, with an average removal efficiency of over 55%, and d) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa), thereby dissolving the polymer, at least one dissolved substance. a) producing a first solution containing contaminants and at least one suspended contaminant, and f) precipitating the first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution containing precipitated polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant, and f) precipitating the second solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa).The method comprises: (a) filtering the polymer by mechanical filtration under a pressure of 0.5 MPa to produce a third solution containing filtered polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant; (b) filtering the third solution by adsorption filtration by contacting it with one or more solid media at a temperature of approximately 90°C to approximately 280°C and a pressure of approximately 200 psig (1.38 MPa) to approximately 9,000 psig (62.05 MPa) to produce a fourth solution containing the polymer filtered twice; and (h) separating the polymer filtered twice from the fourth solution to produce a higher purity polymer, wherein the second fluid solvent has the same or a different chemical composition as the first fluid solvent. [Brief explanation of the drawing]

[0028] [Figure 1A] This is a block flow diagram showing the main processes of one embodiment of the present invention. [Figure 1B] This is a block flow diagram showing the main steps of another embodiment of the present invention. [Figure 2] This is a calibration curve for calculating the polyethylene component in polypropylene using enthalpy values ​​obtained by DSC measurement. [Figure 3] This is a schematic diagram of the experimental apparatus used in the dissolution, precipitation, filtration, and separation processes. [Modes for carrying out the invention]

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

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

[0031] As used herein, the term “post-consumer use” refers to the source of a material after the end consumer has used that material in a consumer good or consumer product.

[0032] As used herein, the term “post-consumer reclaimed” (PCR) refers to material generated after the end consumer has used the material and disposed of it in the waste flow.

[0033] As used herein, the term “post-industrial reclaimed” (PIR) refers to a source of material that originates during the manufacture of a product or item and before its consumer use.

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

[0035] As used herein, the term “dissolved” means that the solute (polymer or nonpolymer) is at least partially incorporated into the solvent at the molecular level. Furthermore, the thermodynamic stability of a solute / solvent solution is given by the following formula: ΔG mix =ΔH mix -TΔS mix This can be explained by the equation, where ΔG mix ΔH is the change in Gibbs free energy of the mixture of solute and solvent. mix ΔS is the enthalpy change of the mixture, T is the absolute temperature, and ΔS mix is the entropy of the mixture. For 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 negative Gibbs free energy at appropriate temperature and pressure can be used in this invention.

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

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

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

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

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

[0041] As used herein, the term “dissolved contaminant” refers to an undesirable or unwanted component that is at least partially incorporated into the solvent at the molecular level.

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

[0043] As used herein in reference to a solution, the term "low suspended contaminants" refers to the state of the solution following a previous condition (e.g., before the contaminant removal step), in which case the previous solution contained a relatively large amount of suspended contaminants.

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

[0045] As used herein, the terms "(one type of) solid medium" and "(multiple types of) solid mediums" refer to a substance that exists in a solid state under the conditions of use. This solid medium may be crystalline, quasicrystalline, or amorphous. This solid medium may be granular and may be supplied in different shapes (i.e., spherical, cylindrical, pellets, etc.). If the solid medium is granular, its particle size and particle size distribution may be defined by the mesh size used to classify the granular medium. An example of standard mesh size notation 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." This solid medium may also be a nonwoven fiber mat or a woven cloth.

[0046] As used herein, the term "higher purity polymer solution" refers to a polymer solution containing one or more contaminants in smaller quantities than the same polymer solution before the purification process.

[0047] As used herein, the term "extraction" refers to the act 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(s) for extraction are explained by distribution theory.

[0048] As used herein, the term "extracted" refers to a material having one or more solute species in a smaller quantity than the same material before the extraction process. As used herein, the term "extracted recycled polymer" refers to a recycled polymer having one or more solute species in a smaller quantity than the same recycled polymer before the extraction process.

[0049] As used herein, the term “non-recycled equivalent” means essentially free of contaminants, colorless and odorless, homogeneous, and having properties similar to non-recycled polymers.

[0050] As used herein, the term "primarily polypropylene copolymer" refers to a copolymer containing more than 70 mol% propylene repeating units.

[0051] As used herein, the term "primarily polyethylene copolymer" refers to a copolymer containing more than 70 mol% ethylene repeating units.

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

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

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

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

[0056] As used herein, the term “pre-coated with filtration aid” refers to a solid-liquid separator in which the filter media consists of a rigid or semi-rigid screen on which one or more layers of fine solid material (e.g., diatomaceous earth, perlite, cellulose fibers, clay, activated carbon, alumina, silica, aluminasilicate, zeolite, and mixtures thereof) are deposited.

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

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

[0059] As used herein, the term “contamination” refers to the total of all contaminants, and the term “chemical contamination” refers to the total of all chemical contaminants. Chemical contaminants are classified into classes that include chemical contaminants having similar chemical structures. For example, As, Hg, and Cr are chemical contaminants in the “heavy metals” classification. Each contaminant may have different chemical attributes, such as solubility and diffusivity in plastics, as well as target levels depending on the concentration and end-use market.

[0060] As used herein, the term “surface contaminant” refers to contaminants present on the surface of a plastic. Similarly, the term “surface chemical contaminant” refers to the molecular or elemental composition of a surface contaminant. Surface contaminants may adhere to the surface of a plastic loosely by physical attraction or more strongly by polar forces or other forces. Generally, less than approximately 80% of the surface area of ​​a surface contaminant is embedded in the plastic.

[0061] As used herein, the term “bulk contaminant” refers to contaminants present in the bulk of plastic. Similarly, the term “bulk chemical contaminant” refers to the molecular or elemental composition of the bulk contaminant. Generally, bulk contaminants have about 80% or more of their surface area embedded within the plastic.

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

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

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

[0065] As used herein, the term “permeable contaminant” refers to a chemical contaminant that is soluble in and diffusive to plastics. Non-limiting examples of permeable contaminants include formaldehyde, bisphenol A, and naphthalene.

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

[0067] As used herein, the term “permeable contamination” refers to the total of all permeable contaminants, and the term “impermeable contamination” refers to the total of all impermeable contaminants. The sum of all permeable and impermeable contamination is “chemical contamination” when described in molecular or elemental terms, but simply “contamination” when described in general terms (e.g., cellulose against paper).

[0068] As used herein, the term “intentional contaminant” refers to a contaminant that is intentionally added by the supply chain for a specific purpose that benefits manufacturers, retailers, or consumers, but which may be undesirable for recycled plastics. Examples include printing, paper labels, label adhesives, pigments (such as TiO2), and processing additives (such as antioxidants-AO) that are necessary for marketing, branding, processability, and / or end-use performance. As used herein, the term “intentional chemical contaminant” refers to an intentional contaminant represented by its chemical composition. As used herein, the term “intentional contamination” refers to the sum of all intentional contaminants, and the term “intentional chemical contamination” refers to the sum of all intentional contaminants represented by their chemical composition.

[0069] As used herein, the surface area-to-volume ratio of a plastic is calculated as follows: For generally spherical objects such as pellets, crushed pellets, and pulverized pellets, the surface area-to-volume ratio is calculated by 3 / r, where r is the mass-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 this invention, the terms "mass-average surface area-to-volume ratio" and "surface area-to-volume ratio" are used interchangeably.

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

[0071] As used herein, the term “densified” refers to a state in which the bulk density of a plastic is higher than that of the original / pre-densified plastic, the original surface area of ​​the plastic is reduced, and / or access to wet fluids is blocked. The process of producing a densified material is called densification.

[0072] As used herein, the term “melt densification” refers to densification performed near the primary melting point of a plastic, at the primary melting point, or above the primary melting point. Non-limiting methods of melt densification include melt extrusion and agglomeration using equipment such as Herbold HV series plast compactors.

[0073] As used herein, the term “primary melting point” refers to the peak melting point of a plastic (the maximum endothermic peak on a zero-gradient baseline) measured using differential scanning calorimetry (DSC). For the purposes of this invention, the terms “primary melting point,” “melting point,” “melting temperature,” and “primary melting temperature” are used interchangeably. For amorphous materials and / or materials lacking a clear melting point, the specified temperature is the approximate softening point of the material, which can be best characterized by the glass transition temperature. Those skilled in the art will understand the validity of the criterion for non-semicrystalline materials.

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

[0075] As used herein, the terms “limit of quantification” or “LOQ” refer to the detection limit of a given chemical contaminant determined by the analytical methods disclosed in Section IX. The LOQ is a function of the method used and may vary from one test method to another. As used herein, the LOQ is specific to the methods enumerated in Section IX.

[0076] As used herein, the term “removal efficiency” refers to the efficiency of a process in removing a particular contaminant, calculated as 100 × (initial concentration - final concentration) / initial concentration, and expressed as a percentage. If the final concentration is lower than the LOQ, for simplification, the removal efficiency is calculated using the LOQ as the final concentration, which is considered the minimum value and is designated as >. In some cases, higher purity plastics may have higher levels of contaminants than recycled polymers due to 1) measurement error, 2) contaminant hotspots and cold spots in the recycled polymer, 3) external contamination during sampling, or 4) contamination added by the purification process. In such cases, the removal efficiency is set to 0% to avoid bias in the average results. If such occurrences occur consistently in a given process, they are more likely to be process-related and should be more rigorously examined, but this has generally not been the case for the processes of the present invention. As used herein, the term “average removal efficiency” refers to the average removal efficiency for each contaminant.

[0077] II. Regenerated Polymers The polymers used in their initial production (non-recycled polymers) by resin suppliers such as Dow, Nova, and ExxonMobil contain very little contamination. However, contamination is introduced, intentionally or unintentionally, throughout the polymer's lifecycle (from manufacturing to distribution, consumer use, and final recycling).

[0078] Non-limited examples of intentional contamination include surface printing, paper labels, label adhesives, pigments (such as TiO2), and processing additives (such as AO) necessary for marketing, branding, processability, and / or end-use performance. Non-limited examples of unintended contamination include dirt, cross-contamination, certain heavy metals, pesticides, dioxins, furans, and PCBs. Unintended contamination can also result from reactions involving intentional contaminants, such as the oxidation of paper labels to dioxins or the decomposition of adhesives or printing binders. The majority of the latter occur during melt densification methods used in recycling processes. Furthermore, oxidation of plastics during melt processing steps, such as those used in the manufacture of the original packaging or product and / or recycling the latter, can result in unintended contamination such as gels. In addition, unintended contamination can occur from interactions with products. For example, packaging materials containing cleaning mixtures (e.g., limonene, surfactants, etc.) or food products (e.g., various organic substances) can be contaminated by such products. Finally, unintended contamination, such as contamination of plastics by reaction by-products or unreacted monomers, can enter the plastic during manufacturing.

[0079] It is recognized that different recycled polymer sources have different contamination and associated risks. Large quantities of recycled polymer streams exist whose origin and lifecycle are unknown, and it is clear that the potential for contamination is very high. On the other hand, controlled recycled polymer streams are available and pose a lower potential risk for demanding applications. For example, if a recycled polymer stream is known to originate from a demanding application, such a stream will not contain undesirable contaminants until it reaches the consumer; otherwise, these plastics would not be approved for use in those applications. Therefore, contamination that would prevent reuse in these same applications would primarily be unintentional contamination originating from external sources and penetrating the plastic through surface contamination. Small amounts of contamination may result from reactions involving intentional contamination, such as the oxidation of cellulosic materials to dioxins during melt densification.

[0080] Pre-use plastics generally have very low levels of contamination because their composition is known and their history is controlled. While pre-use plastics may contain intentional contamination such as surface printing and opacifiers, these are known and controlled, making it very easy to find applications that tolerate such known contaminants. Furthermore, because pre-use plastics have a controlled history, external contamination is prevented, resulting in less unintended contamination. Therefore, pre-use plastics originally intended for demanding applications become an ideal source of recycled polymers for the same end market with minimal washing / purification. The latter pre-use plastics in film form are called "Approved Sourced Post-Industrial Film" (ASPIF). A disadvantage is that the ASPIF flow is very limited and does not maintain circularity.

[0081] Consumer end-of-use plastics are generally more contaminated than pre-use plastics. The post-market subclass of consumer end-of-use plastics has the second lowest level of contamination, after pre-use recycled plastics, given that its lifecycle within the commercial supply chain is reasonably controlled. Generally, post-market recycled plastics have known and controlled levels of intentional contamination and are therefore capable of broad use as recycled polymers. However, unintentional contamination is ubiquitous and is known to cause problems in this flow, hindering widespread use in demanding applications. Post-market plastics supplied from demanding applications can potentially be returned to these sectors for use after proper cleaning / purification. Post-market plastics supplied in film form from demanding applications are called "Approved Source Post-Commercial Film" (ASPCF). To address the ongoing need for higher-purity recycled polymers, recycling material suppliers have recently introduced post-market film sources with more controlled and known histories. These new sources are called high-custody sources and are primarily used in post-market film flows. In other words, highly controlled post-market film sources should have lower levels of contamination compared to general post-market film sources. The disadvantages are that these highly controlled sources have limited capacity and are more expensive.

[0082] The post-consumer and post-household subclass of plastics exhibits extremely high levels of contamination, given that their lifecycle within commercial channels is uncontrolled. Such plastics are highly variable, unpredictable, and possess both high levels of intentional and unintentional contamination that are uncontrolled. Such plastics may include plastic sources that were originally unacceptable for use in demanding applications. Consequently, the market for these plastic sources is limited and essentially nonexistent in demanding applications.

[0083] Remarkably, the higher-purity plastics produced by this invention may enable a wider range of applications in demanding fields with certain limitations, using plastics sourced from industrial end-of-use (both ASPIF and uncontrolled sources), post-market (both ASPCF and uncontrolled sources), and post-household end-of-use plastics. In addition, most recycled material customers are seeking materials of higher purity than those currently available, and the higher-purity plastics of this invention meet this broader need for higher-purity plastics from any source.

[0084] For the purposes of the present invention, non-limiting examples of polymers include films, sheets, injection-molded parts, blow-molded parts, fibers, nonwovens, wovens, thermoformed parts, and extruded strands.

[0085] The recycled polymer may be a plastic of a first age (used only once before entering the recycled polymer stream), a plastic of a second age (used twice before entering the recycled polymer stream), or a plastic of a longer age (used many times before entering the recycled polymer stream). In embodiments of the present invention, the recycled polymer includes non-recycled plastics. In embodiments of the present invention, the recycled polymer includes films. In embodiments of the present invention, the recycled polymer is selected from the group including films, injection-molded parts, blow-molded parts, fibers, nonwovens, wovens, thermoformed parts, extruded strands, or mixtures thereof.

[0086] In embodiments of the present invention, the recycled polymer includes reground / scrap / industrial waste plastic. In embodiments of the present invention, the recycled polymer includes PIR polymer. In embodiments of the present invention, the recycled polymer includes PIR polymer film. In embodiments of the present invention, the recycled polymer includes PIR polymer nonwoven fabric. In embodiments of the present invention, the PIR polymer film is ASPIF. In embodiments of the present invention, the recycled polymer includes PCR polymer. In embodiments of the present invention, the recycled polymer includes PCR polymer film. In embodiments of the present invention, the recycled polymer includes PCR polymer nonwoven fabric. In embodiments of the present invention, the PCR polymer film is ASPCF. In embodiments of the present invention, the recycled polymer includes high-control PCR polymer film. In embodiments of the present invention, the recycled polymer includes post-use polymer. In embodiments of the present invention, the recycled polymer includes post-use polymer film. In embodiments of the present invention, the recycled polymer includes post-use polymer nonwoven fabric.

[0087] In embodiments of the present invention, the recycled polymer includes PS, copolystyrene, PA, copolyamide, PC, thermoplastic elastomer, styrene block copolymer, polyester, copolyester, PVC, and any of the above copolymers and mixtures thereof. In embodiments of the present invention, the recycled polymer includes polyolefin, polyolefin copolymer, and polyolefin polar copolymer. In embodiments of the present invention, the recycled polymer includes LDPE and LLDPE copolymer. In embodiments of the present invention, the recycled polymer includes PP. In embodiments of the present invention, the recycled polymer includes HDPE and HDPE copolymer. In embodiments of the present invention, the recycled polymer includes a film, and the film includes polyethylene and polyethylene copolymer.

[0088] In an embodiment of the present invention, the recycled polymer is a PCR polymer. In an embodiment of the present invention, the recycled polymer is a homopolymer of polypropylene or a copolymer mainly composed of polypropylene. In an embodiment of the present invention, the recycled polymer is a homopolymer of polyethylene or a copolymer mainly composed of polyethylene. In an embodiment of the present invention, a method for purifying the recycled polymer includes obtaining the recycled polymer, and the recycled polymer is selected from the group consisting of PCR polymers, PIR polymers, and combinations thereof. The recycled polymer may be in many forms including, but not limited to, pellets, micronized pellets, ground pellets, shredded films, shredded or ground injection molded parts, shredded or ground blow molded parts, thermoformed parts, shredded non-woven or woven fabrics, extruded strands, or agglomerated particles. In an embodiment of the present invention, the recycled polymer includes pellets.

[0089] In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio greater than about 1 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio greater than about 5 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio greater than about 20 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio greater than about 50 mm -1 In an embodiment of the present invention, the recycled polymer has an average surface area to volume ratio greater than about 50 mm.

[0090] An objective of the present invention is that recycled polymers originate from post-consumer use, post-industrial use, post-market, and / or other special recyclable waste flows. For example, PCR polymers may originate from curbside recycled flows, where end consumers place used polymers from packaging and products into designated containers for collection by waste carriers or recyclers. PCR polymers may also originate from in-store "return" programs, where consumers bring waste polymers to stores and place them into designated collection containers. An example of PIR polymers may be waste polymers generated during the manufacture or transport of goods or products that are collected by manufacturers as unusable materials (i.e., fabric scraps, off-specification materials, starter scraps). An example of waste polymers from special waste flows may be waste polymers derived from the recycling of electronic waste (also known as electronic junk). Another example of waste polymers from special waste flows may be waste polymers derived from automobile recycling. Another example of waste polymers from special waste flows may be waste polymers derived from the recycling of used carpets and fabrics.

[0091] An object of the present invention is that a recycled polymer is a homogeneous composition of individual polymers or a mixture of several different polymer compositions. Non-limiting examples of recycled polymer compositions include homopolymers and copolymers of polyolefins such as polyethylene and isotactic polypropylene, polyesters such as poly(ethylene terephthalate), vinyl polymers such as poly(vinyl chloride), styrene polymers such as polystyrene, polyamides such as poly(hexamethylene adipamide), polycarbonates such as poly(bisphenol A carbonate), polyacrylates such as poly(methyl methacrylate), polysiloxanes such as poly(dimethylsiloxane), thermoplastic elastomers such as styrene-butadiene block copolymer and ethylene-propylene rubber, and other soluble polymers that may be apparent to those skilled in the art.

[0092] Recycled polymers may also contain a variety of pigments, dyes, processing aids, stabilizers, fillers, and other performance-enhancing additives added to the polymer during polymerization or conversion of the original polymer into the final form of the article. Non-limiting examples of pigments include organic pigments (e.g., copper phthalocyanine), inorganic pigments (e.g., titanium dioxide), and other pigments that may be apparent to those skilled in the art. A non-limiting example of an organic dye is Basic Yellow 51. Non-limiting examples of processing aids include antistatic agents (e.g., glycerol monostearate) and lubrication accelerators (e.g., erucic acid amide). A non-limiting example of a stabilizer is octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate. Non-limiting examples of fillers include calcium carbonate, talc, and glass fibers.

[0093] III. Pollutants Contaminants can generally be classified into two mobility categories: 1) permeable; and 2) impermeable. Permeable contaminants have solubility and diffusivity in regenerating polymers, allowing them to move into, through, and out of the polymer due to a chemical potential gradient. In other words, the group called permeable contaminants and permeable contamination is mobile. Impermeability means that the contaminant does not have sufficient solubility and diffusivity to move significantly into, through, and out of the polymer. In other words, impermeable contamination, represented by the sum of all impermeable contaminants, is essentially immobile. That is, once impermeable contamination is initially deposited, such contamination remains in place until it is physically removed, moved by convection, or brought into contact with a different material that is permeable to the contaminant.

[0094] Numerous chemical contaminants can be present in recycled polymers, but they generally fall into one of several relevant chemical classifications. Non-limiting examples of relevant chemical classifications include pesticides, aldehydes, allergenic fragrances, izioalines, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, organotin compounds, metals, phthalates, and polyaromatic hydrocarbons (PAHs). Only a portion of these chemical classifications are routinely found in recycled polymers before and after consumer use, including pesticides, alkylphenol ethoxylates, alkylphenols, bisphenols, dioxins, dioxin-like compounds, furans, PCBs, metals, organotin compounds, phthalates, and PAHs.

[0095] Using the analytical methods disclosed in Section IX, the LOQs of various contaminants can vary by orders of magnitude. For example, the LOQ of a typical pesticide is approximately 10 ppb. The LOQ of a typical alkylphenol ethoxylate is approximately 50 ppb. The LOQ of a typical alkylphenol is approximately 5 ppb. The LOQ of bisphenol A is approximately 5 ppb. The LOQ of a typical dioxin is approximately 0.2 ppt. The LOQ of a typical furan is approximately 0.2 ppt. The LOQ of a typical PCB is approximately 5 ppt. The LOQ of a typical heavy metal is approximately 100 ppb. The LOQ of a typical organotin is approximately 300 ppt. The LOQ of a typical phthalate is 50 ppb. The LOQ of a typical PAH is 1 ppb.

[0096] As shown in Tables 1a to 1i, several film sources, including three ASPIF sources, three high-control post-market film sources, three post-market film sources, and one household post-use film source, were broadly classified for chemical contamination using the analytical methods disclosed in Section IX. To simplify the presentation of chemical contamination results, concentration data are expressed in LOQ rather than absolute weight fraction. For example, if the contaminant concentration is 10 ppm and the LOQ is 1 ppm, the concentration is either 10 × LOQ or exactly 10 as shown in the data table. Also, "dnt" is an abbreviation for "test not performed".

[0097] Table 1a~Table 1i Chemical contamination of ASPIF, Highly Controlled Post-Market (HCPC), Post-Market (PC), and Post-Household Use (PH) film sources.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] [Table 4]

[0102] [Table 5]

[0103] [Table 6-1]

[0104] [Table 6-2]

[0105] [Table 7]

[0106] [Table 8]

[0107] [Table 9]

[0108] The tested ASPIF sources were essentially free of detectable levels of chemical contaminants, with the exception of alkylphenols, heavy metals, and small amounts of organotin and PAHs. The chemical contaminant results for these ASPIF sources serve as an indicator of the level of chemical contamination representative of these controlled end markets and demonstrate that heavy metals, which have a low risk of transfer, are ubiquitous across all film sources. Therefore, heavy metals were excluded from the ongoing analysis in this application. The tested highly controlled post-market film sources contained little to no pesticides and alkylphenol ethoxylates, but did contain detectable levels of alkylphenols, bisphenol A, dioxins / furans / PCBs, and PAHs, as well as low levels of phthalates. The tested post-market film sources were heavily contaminated in all classes evaluated; for example, dioxins were typically present at concentrations as high as 40 × LOQ, but in one source, dioxins were present at concentrations as high as 200 × LOQ. The tested post-use household supply sources were the most heavily contaminated, with high concentrations of dioxins (300 × LOQ) and PCBs (180 × LOQ).

[0109] From Tables 1a to 1i, representative chemical species were selected from various classes based on the spectral distribution of recycled polymer sources. The selected chemicals within these classes are piperonyl butoxide, representing pesticides; 4-t-octylphenol hexaethoxylate and isononylphenol triethoxylate, representing alkylphenol ethoxylates; isononylphenol and 4-tert-pentylphenol, representing alkylphenols; bisphenol A, representing phenols; 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD, and OCDD, representing dioxins; OCDF, representing furans; PCB105 and PCB118, representing PCBs; monobutyltin and dibutyltin, representing organotin compounds; dibutyl phthalate and di-2-ethylhexyl phthalate, representing phthalates; and fluoranthene and phenanthrene, representing PAHs (Table 2).

[0110] In embodiments of the present invention, the chemical contaminants in the recycled polymer include at least one chemical contaminant selected from the group including pesticides, alkylphenols, alkylphenol ethoxylates, bisphenols, dioxins, furans, PCBs, phthalates, PAHs, or mixtures thereof.

[0111] In embodiments of the present invention, the pesticide comprises piperonyl butoxide, BAC, DEET, and DDAC. In embodiments of the present invention, the alkylphenol ethoxylate comprises isononylphenol monoethoxylate, isononylphenol diethoxylate, isononylphenol triethoxylate, and isononylphenol tetraethoxylate. In embodiments of the present invention, the alkylphenol comprises isononylphenol, 4-tert-butylphenol, and 4-tert-pentylphenol. In embodiments of the present invention, the bisphenol comprises bisphenol A. In embodiments of the present invention, the dioxin comprises 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD, and OCDD. In embodiments of the present invention, the furan comprises OCDF. In embodiments of the present invention, the PCB comprises PCB77, PCB81, PCB126, PCB105, PCB114, PCB118, PCB123, PCB156, and PCB167. In embodiments of the present invention, the phthalate includes di-2-propylheptyl phthalate, diisobutyl phthalate, dibutyl phthalate, di-1-ethylhexyl phthalate, and diisononyl phthalate. In embodiments of the present invention, the PAH includes acenaphthene, acenaphthylene, anthracene, benzo[a]anthracene, benzo[b]fluorantene, benzo[e]pyrene, benzo[ghi]perylene, chrysene, cyclopenta[cd]pyrene, fluorantene, fluorene, naphthalene, phenanthrene, and pyrene. In embodiments of the present invention, the organotin includes monobutyltin, dibutyltin, and dioctyltin.

[0112] In embodiments of the present invention, the contaminant in the recycled polymer may include 4-tert-pentylphenol. In embodiments of the present invention, the contaminant in the recycled polymer may include bisphenol A. In embodiments of the present invention, the contaminant in the recycled polymer may include OCDD. In embodiments of the present invention, the contaminant in the recycled polymer may include PCB118. In embodiments of the present invention, the contaminant in the recycled polymer may include di-2-ethylhexyl phthalate.

[0113] To simplify the presentation of purification results for the objects of the present invention and related examples, the number of chemical species presented for each chemical classification is limited to the aforementioned representative chemical species for each chemical classification, as shown in Table 2, along with the relevant LOQ and respective levels for the ASPIF source tested. Even if more detailed and complete chemical analysis has been completed for all objects of the present invention, only the selected chemicals are shown as ongoing. This simplification does not affect or alter the content of the present invention or the conclusions drawn therefrom. The selected chemicals appropriately and consistently represent a broader class with respect to purification.

[0114] [Table 10]

[0115] In embodiments of the present invention, the concentration of each pesticide in the higher-purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable pesticide. In embodiments of the present invention, the concentration of bisphenol A in the higher-purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable bisphenol A. In embodiments of the present invention, the concentration of each dioxin in the higher-purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable dioxin. In embodiments of the present invention, the concentration of each PCB in the higher-purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable PCB. In embodiments of the present invention, the concentration of each phthalate in the higher-purity plastic is lower than its respective LOQ, and the recycled polymer has at least one detectable phthalate.

[0116] In embodiments of the present invention, the concentration of piperonyl butoxide in the higher purity plastic is less than about 10 ppb, and the recycled polymer has a piperonyl butoxide concentration greater than 10 ppb; the concentration of 4-tert-pentylphenol in the higher purity plastic is less than about 5 ppb, and the recycled polymer has a 4-tert-pentylphenol concentration greater than 5 ppb; and the concentration of bisphenol A in the higher purity plastic is less than about 5 ppb, and the recycled polymer has a bisphenol A concentration greater than 5 ppb. The OCDD concentration in higher-purity plastics with phenol A concentration is less than approximately 0.2 ppt, while the recycled polymer has an OCDD concentration greater than 0.2 ppt; the PCB118 concentration in higher-purity plastics is less than approximately 10 ppt, while the recycled polymer has a PCB118 concentration greater than 10 ppt; and the di-2-ethylhexyl phthalate concentration in higher-purity plastics is less than approximately 50 ppb, while the recycled polymer has a di-2-ethylhexyl phthalate concentration greater than 50 ppb.

[0117] In embodiments of the present invention, the removal efficiency of piperonyl butoxide contaminants is greater than 55%, and the concentration of piperonyl butoxide in the regenerated polymer is at least 10 ppb. In embodiments of the present invention, the removal efficiency of piperonyl butoxide contaminants is greater than 85%, and the concentration of piperonyl butoxide in the regenerated polymer is about 10 ppb or more.

[0118] In embodiments of the present invention, the removal efficiency of 4-tert-pentylphenol contaminants is greater than 55%, and the concentration of 4-tert-pentylphenol in the regenerated polymer is at least 5 ppb. In embodiments of the present invention, the removal efficiency of 4-tert-pentylphenol contaminants is greater than 85%, and the concentration of 4-tert-pentylphenol in the regenerated polymer is at least 5 ppb.

[0119] In embodiments of the present invention, the removal efficiency of bisphenol A contaminants is greater than 55%, and the concentration of bisphenol A in the regenerated polymer is at least 5 ppb. In embodiments of the present invention, the removal efficiency of bisphenol A contaminants is greater than 79%, and the concentration of bisphenol A in the regenerated polymer is about 5 ppb or greater.

[0120] In the embodiments of the present invention, the removal efficiency of OCDD contaminants is greater than 55%, and the concentration of OCDD in the regenerated polymer is greater than approximately 0.2 ppt. In the embodiments of the present invention, the removal efficiency of OCDD contaminants is greater than 95%, and the concentration of OCDD in the regenerated polymer is greater than approximately 0.2 ppt.

[0121] In the embodiments of the present invention, the removal efficiency of OCDF contaminants is greater than 55%, and the concentration of OCDF in the regenerated polymer is greater than approximately 0.2 ppt. In the embodiments of the present invention, the removal efficiency of OCDF contaminants is greater than 93%, and the concentration of OCDF in the regenerated polymer is greater than approximately 0.2 ppt.

[0122] In embodiments of the present invention, the removal efficiency of PCB118 contaminants is greater than 55%, and the concentration of PCB118 in the recycled polymer is at least 10 ppt. In embodiments of the present invention, the removal efficiency of PCB118 contaminants is greater than 66%, and the concentration of PCB118 in the recycled polymer is about 10 ppt or more.

[0123] In embodiments of the present invention, the removal efficiency of di-2-ethylhexyl phthalate contaminants is greater than 55%, and the concentration of di-2-ethylhexyl phthalate in the regenerated polymer is greater than approximately 50 ppb. In embodiments of the present invention, the removal efficiency of di-2-ethylhexyl phthalate contaminants is greater than 78%, and the concentration of di-2-ethylhexyl phthalate in the regenerated polymer is greater than approximately 50 ppb.

[0124] In embodiments 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 embodiments 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.

[0125] Contamination can be located on the surface of the plastic or within the bulk. Surface contamination can be removed very easily and readily by surface cleaning technologies available on the market today. If the surface contamination is permeable to the plastic, it will become bulk contamination over time by diffusion mechanisms, thus complicating reduction and limiting the effectiveness of surface cleaning technologies. If the surface contamination is impermeable to the plastic, such contamination will not diffuse into the bulk and can be reduced by simple surface cleaning methods such as aqueous cleaning. Bulk contamination, whether of the permeable or impermeable type, is often not effectively removed by simple surface cleaning methods such as aqueous cleaning. Impermeable bulk contamination (also known as bulk impermeable contamination) can be trapped within the bulk plastic and released by mechanisms including melt convection, melt filtration, or dissolution / decomposition of the bulk plastic.

[0126] As mentioned above, contamination can be introduced from external sources throughout the entire lifecycle of a plastic. If the contamination is impermeable, it will largely remain on the surface throughout the plastic's lifecycle up to the point of regeneration. If the contamination is permeable, it will move into the bulk plastic over time. Therefore, in the absence of contamination or purification events, the contamination remains essentially constant, although the balance between surface contamination and bulk contamination changes over time, approaching equilibrium over a long period. Generally, loosely bound surface contamination, such as dirt, can be as high as 0.01 to about 0.1% by weight. On the other hand, chemical contamination, particularly the chemical contaminants of concern in this invention, can be at the ppm, ppb, or even ppt levels.

[0127] Permeable and impermeable contamination presents a variety of challenges in demanding applications. For example, permeable contamination, whether in the bulk plastic or on the plastic surface, can migrate to uncontaminated materials such as products or to human skin. Therefore, if packaging contains permeable contaminants, such contaminants may migrate into the product, rendering it unsuitable for these demanding end markets. However, if the contaminant is impermeable and present in the bulk plastic, its ability to migrate to the product or the user's skin is low unless the bulk plastic is decomposed or ingested. Therefore, packaging may use this contaminated plastic material, and there may be no risk of contamination migrating to the product or directly to the skin. However, if the contaminant is impermeable and present on the plastic surface, such contamination has the ability to migrate to the product or skin by direct contact migration, making it unacceptable for use in these demanding applications. Both permeable and impermeable surface contamination can be converted to bulk contamination by convection mechanisms such as melt mixing and melt densification. These methods replace or reduce the surface area with bulk material. For example, if a surface-contaminated film is melt-densified or melt-extruded into a different shape such as pellets, all of the original surface contamination, whether impermeable or not, becomes bulk contamination, and such bulk contamination becomes more difficult to remove in the refining process. Melt-densification is common in the recycling industry. Also common in the recycling industry is shredding incoming plastics. The latter method generally does not convert surface contamination into bulk contamination. Ideally, surface refining methods such as surface washing should be performed on the original contaminated surface, such as shredded film, so that the surface washing fluid can reach all of the original surface area.

[0128] Generally, it is difficult to distinguish between surface contamination and bulk contamination using analytical methods. Most analytical methods for permeable chemical contaminants involve solvent extraction of contaminants from plastics over a long period of time exceeding 6 hours, exposure to extreme solvent-to-plastic mass ratios greater than 100:1, and then quantifying the contaminants in the solvent using methods such as gas chromatography-mass spectrometry (GC-MS). Such analytical methods quantify contamination but do not distinguish between surface contaminants and bulk contaminants. The efficiency of purification methods for removing surface contamination can be estimated from the difference in contamination before and after the surface cleaning process, but this assumes that bulk contamination is not significantly affected, as in the case of surface cleaning with aqueous surface cleaning fluids discussed in this invention. A more accurate method for quantifying surface contamination is to wash the contaminants at various time points, then solvent extract them, and then extrapolate the amount of contaminants removed at the smallest time point to approximate the amount of surface contamination. However, this method is time-consuming and expensive, especially for contaminants that are generally difficult to measure. Furthermore, because the balance between surface contaminants and bulk contaminants is dynamic, quantification is difficult without referring to precise sampling times. A simple method for quantifying general surface contamination (not chemical surface contamination or chemical contaminants based on chemical species) is to weigh the recycled polymer before and after the surface cleaning process.

[0129] In general, bulk contamination is not significantly removed by simple aqueous surface cleaning. Permeable bulk contamination can be removed by diffusion mechanisms via chemical potential gradients. Impermeable bulk contamination is essentially trapped by bulk polymers, and methods for removing the trapped contaminants include melt convection, melt filtration, and dissolution / decomposition of plastics.

[0130] 1. In embodiments of the present invention, a method for purifying a regenerated polymer is to obtain a regenerated polymer, wherein the regenerated polymer is selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer contains contaminants, each contaminant has a concentration, and the contaminants of the regenerated polymer include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates. In embodiments of the present invention, a method for purifying a regenerated polymer is to obtain a regenerated polymer, wherein the regenerated polymer is selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer contains contaminants, each contaminant has a concentration, and the contaminants of the regenerated polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate. In embodiments of the present invention, alkylphenol, bisphenol, dioxin, PCB, and phthalate include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate.

[0131] IV. Surface purification Surface purification reduces surface contamination. One such method is surface cleaning with a surface cleaning fluid, typically aqueous. Surface cleaning is ideally completed before melt mixing or melt densification to allow for effective cleaning of the original contaminated surface. Recycled polymers generally come in forms such as pellets, loose or compressed films, loose or compressed flexible packaging, loose or compressed rigid materials, and loose or compressed nonwoven fabrics, and their overall size is too large to be easily cleaned. Therefore, a granulation or shredding process is preferable before surface cleaning. In the case of films, it is particularly important to remove all available film layers so that the cleaning fluid can access all original surface contamination. Therefore, the size reduction process before surface cleaning should not significantly reduce the average surface area-to-volume ratio of the recycled resource, nor replace it with new surface areas.

[0132] In embodiments of the present invention, surface cleaning of the recycled polymer is performed after a shredding or granulation step. Surface cleaning involves loosening surface dirt and other contaminants, physical removal, and vigorous mechanical stirring to allow the dirt or other contaminants to move into a cleaning fluid in which they may or may not be solubilized.

[0133] As used herein, in a surface cleaning process, the recycled plastic is brought into contact with an aqueous solution under mechanical agitation in its original contaminated form (except in cases where reducing the bulk size may result in a reduction of less than 25% of the original surface), and then separated from the aqueous medium containing such contaminants. Such a surface cleaning process generally removes most of the loosely bound surface contaminants, including but not limited to dirt, wood, loosely bound paper, and any surface chemical contaminants. A typical level of loosely bound surface contaminants in the case of film-based recycled resources is about 0.01–0.1% by weight. In embodiments of the present invention, surface cleaning removes more than about 80% of the loosely bound surface contaminants.

[0134] Surface cleaning technologies are widely available on the market. One technology is from Lindner (Lindner Washtech GmbH, Haldenfeld 4, Germany). This technology is described in detail elsewhere (https: / / www.lindner-washtech.com / system-solutions) and involves rinsing under vigorous mechanical agitation, as well as the application of caustic alkali to remove adhesives, followed by drying and pelletizing. Another technology is from Herbold (Herbold Meckesheim USA, North Smithfield, Rhode Island, USA). This technology is described in detail elsewhere (https: / / www.herbold.com / en / machines / washing-separating-drying-2 / ) and also includes various rinsing steps under vigorous mechanical agitation, followed by drying and pelletizing. Another technology is from Sorema (Sorema Srl, Anzano del Parco, Italy). This technique, described in detail elsewhere (http: / / sorema.it / en_US / applications / washing-line / ), involves similar aqueous operations compared to Lindner and Herbold. Finally, another technique, called deinking, comes from Cadel (Cadel Deinking, Alicante, Spain). This technique, described elsewhere (http: / / cadeldeinking.com / en / ), essentially involves washing the surface of a material using a hot aqueous solution containing a specific surfactant, followed by rinsing with water and drying. This process may optionally include densification, melt filtration, defloration, and pelletizing after surface washing. This method differs from other known methods in that it removes surface-printed ink. This would be advantageous in reducing the burden of chemical contaminant removal by the bulk purification method of the present invention.

[0135] Three conventional surface cleaning techniques were evaluated for their average removal efficiency of five selected contaminants (Comparative Examples 1, 2, and 3). Each surface cleaning technique was evaluated using different recycled films with varying levels of contamination. Overall, the conventional surface cleaning techniques failed to purify the recycled polymers to a degree sufficient for use in a controlled end market. Commercial techniques failed to reduce the selected contaminants to near-LOQ levels, even though the initial contamination of each recycled polymer was minor. In addition, the average removal efficiency of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate was less than approximately 55%.

[0136] In embodiments of the present invention, the regenerated polymer is surface-cleaned in a non-densified state in a surface cleaning step prior to the leaching step to produce a surface-cleaned polymer, and the surface cleaning results in a reduction of more than 80% of loosely bound surface contamination. -1 Having an average surface area-to-volume ratio of less than 10%, the surface cleaning process is a deinking type surface cleaning process, and the deinking process results in a ΔE change of less than approximately 10% between the deinked polymer and the regenerated polymer that does not contain surface-printed ink.

[0137] V. Melt-densification Assuming the surface refining temperature was below the primary melting point of the recycled polymer, the plastics emerging from the surface refining process generally have a similar geometric morphology and a similar average surface area-to-volume ratio to the incoming recycled polymer. For example, if the recycled plastic is in the form of a loose film, after shredding and surface washing at a temperature below the primary melting point of the recycled polymer, the film exits the surface refining process as a shredded film. Since such loose plastics are difficult to feed into certain bulk refining methods such as liquid-liquid extraction, it may be desirable to melt and densify such plastics before bulk refining.

[0138] A preferred method for melt densification is melt extrusion. Melt extrusion not only densifies the plastic but can also provide the pressure required for downstream bulk purification, such as liquid-liquid extraction. Melt extrusion may also include optional steps such as melt filtration and / or defloration to remove large bulk contaminants and / or volatile bulk contaminants. In addition, the melt-densified plastic may be further pressurized using a melt pump. The melt pump may be necessary to increase the pressure required for downstream bulk purification steps. Other densification methods, including rotary disk densifiers and rotary drum densifiers, which are performed at lower temperatures compared to melt-based methods, are known in the art.

[0139] In embodiments of the present invention, melt densification includes melt extrusion. In embodiments of the present invention, melt extrusion includes melt filtration. In embodiments of the present invention, melt extrusion includes melt defloration. In embodiments of the present invention, melt extrusion includes melt pumping. In embodiments of the present invention, melt densification includes melt extrusion, melt filtration, melt defloration, and melt pumping.

[0140] VI. Immersion leaching Unexpectedly, a combined surface purification and immersion leaching process (disclosed in Section VII), in combination with an immersion leaching process (disclosed in Section VI) or a purification process (disclosed in Section VIII), was found to produce higher purity polymers from recycled polymers with far greater efficiency than when the purification process was used alone. While we do not wish to be bound by any theory, we assume that the removal of contaminants in the leaching process enables higher efficiency of residual contaminant removal in the various stages of the purification process compared to the absence of the leaching process or the surface purification and leaching process. While we do not wish to be bound by any theory, we believe that surface contaminants of recycled polymers become bulk contaminants in the absence of the leaching process or the surface purification and leaching process, and are therefore difficult to remove in the various stages of the purification process.

[0141] In general, bulk contamination is not significantly reduced by simple aqueous surface cleaning. While melt filtration and melt defoliation can remove large geometrically sized bulk contaminants and some volatile bulk contaminants, they are often ineffective against most bulk contaminants to the level particularly required.

[0142] One commercially available technology for bulk refining is the InterRema Refresher® from EREMA (EREMA Group, Ansfelden, Austria; https: / / www.erema.com / en / refresher / ). While this technology is described in detail elsewhere, it essentially involves defolazing pelletized material over a long period at temperatures below the primary melting point of the plastic to remove volatile organic compounds. Most of the chemical contaminants related to recycled polymers, as discussed in the previous section, typically have standard boiling points above 200°C and are highly non-volatile. Therefore, this type of defolalation technology has limited ability to remove most of the chemical contaminants mentioned in this application.

[0143] Other devolatilization-based techniques are common. These may be independent unit operations or combined with other operations, including extrusion and melt filtration. They commonly utilize pressures below atmospheric pressure for the molten flow of recycled plastics. One bulk refining technique involving devolatilization was analyzed for its refining capacity. This technique included a temperature slightly higher but lower than the primary melting point of the plastic, a long residence time (over approximately 2 hours), and continuous reflux of purified air to provide devolatilization (Comparative Example 4). Commercial devolatilization techniques failed to adequately remove selected contaminants. For example, the selected contaminants still far exceeded the LOQ, and the average removal efficiency was approximately 41%.

[0144] Extraction is a preferred bulk purification method. Extraction involves the use of a purified solvent to remove bulk permeable contaminants by creating a chemical potential gradient between the recycled polymer and the solvent. The removal rate of permeable chemical contaminants depends on the diffusivity and solubility of the contaminants to the plastic under the conditions that arise during the process. For high MW plastics, the diffusivity of large molecules exhibiting chemical contaminants is very low, especially in the solid state of the plastic. Furthermore, solubility may be limited due to the high MW and lack of enthalpy mixing of the recycled polymer. Therefore, the time required to remove permeable contaminants by diffusion mechanisms is very long and may not contribute to an economically viable process on a commercial scale. Methods to overcome these timescale limitations include 1) plastic relaxation by increased diffusivity and / or solvent swelling due to high temperature, 2) reduction of diffusion path length by increasing the average surface area to volume ratio of the recycled polymer exposed to the solvent, and 3) increased convective transport of contaminants through the plastic / solvent interface by increasing the solubility of the contaminants to the solvent, improved distribution of contaminants to the solvent compared to the plastic, increased convection around the plastic / solvent interface, and increased solvent sink compared to plastic sink. The solubility of bulk purification solvents in plastics can be improved, particularly by operating the extraction at critical pressure, near critical pressure, or above critical pressure.

[0145] It is important that the extraction method is low-cost and scalable to large volumes. Therefore, in order to enable such scalability, the time required for extraction must be reduced. In embodiments of the present invention, the total extraction time is less than about 6 hours, preferably less than about 4 hours, more preferably less than about 2 hours, and even more preferably less than about 1 hour. If the extraction is completed in stages, the time per stage may be less than this range, but the total time will still fall within these limits.

[0146] Extraction can be performed above the primary melting point of the recycled polymer, near the primary melting point, at the primary melting point, or below the primary melting point. Extraction performed at, near, or above the primary melting point of the recycled polymer is called liquid-to-liquid extraction. Extraction performed below the primary melting point of the recycled polymer is called leaching extraction, or simply the leaching process. The extraction solvent used in leaching extraction is called the leaching solvent.

[0147] In the immersion leaching process of the present invention, the regenerated polymer is exposed to an excess solvent at all stages and points in the process. Such a leaching process is called an immersion leaching process. For the purposes of this invention, the terms "immersion leaching" and "leaching" are used interchangeably. Also for the purposes of this invention, the terms "process," "step," "process steps," and their plural forms are used interchangeably.

[0148] In the leaching process, the mass ratio of the leaching solvent to the mass of the regenerated polymer exposed to the solvent is preferably about 5:1 or greater at all points and stages of the process. In some leaching processes, the solvent is rapidly agitated so that the regenerated polymer is suspended in the solvent, even if the density of the regenerated polymer is greater than the density of the solvent. Such leaching processes ensure complete contact between the surface of the regenerated polymer and the leaching solvent, reducing the resistance of mass transfer within the solvent boundary layer around the surface of the regenerated polymer due to convection. In addition to agitation, a similar reduced boundary layer can be achieved in immersion leaching processes by precipitating the regenerated polymer through the solvent by a density gradient. Examples of immersion leaching processes include continuous-type agitated tanks (also known as continuous-type agitated reactors - CSTRs), semi-continuous-type agitated tanks, and batch-type agitated tanks. A further example of an immersion leaching process is a sedimentation tank, which allows the regenerated polymer to precipitate through a solvent filled inside a tank or other container. The applicants have found that, in the immersion leaching process of the present invention, the mass ratio of the leaching solvent to the regenerated polymer at any point in time and at any stage should preferably be greater than about 5:1, more preferably greater than 10:1 per stage, and most preferably greater than about 20:1, in order to enable proper dispersion and exfoliation of the regenerated polymer in the leaching solvent.

[0149] In embodiments of the present invention, the immersion leaching process is carried out in a stirred tank. In embodiments of the present invention, the immersion leaching process is carried out in a CSTR. In embodiments of the present invention, the immersion leaching process is carried out in a batch stirred tank. For all stirred tank processes, the ability to expose the surface area of ​​the recycled polymer to the leaching solvent is important. The reactor design should include the possibility of vigorous mechanical stirring and the use of baffles for extended periods.

[0150] In the immersion leaching process of the present invention, it may be beneficial to select the leaching solvent, as well as 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, and can locally increase the concentration gradient when the refluxed solvent comes into contact with the regenerated polymer.

[0151] In embodiments of the present invention, the immersion leaching process is carried out at a temperature below the primary melting point of the recycled polymer and at a pressure near atmospheric pressure to about 1,000 atm. In embodiments of the present invention, the immersion leaching process is carried out at a temperature below the primary melting point of the recycled polymer and at a pressure near atmospheric pressure to about 1,000 atm, using a leaching solvent, in multiple leaching stages over the total residence time of the immersion leaching process and the residence time of each leaching stage.

[0152] In embodiments of the present invention, the leaching solvent has a standard boiling point or nearby. For polyolefin recycled polymers, preferred leaching solvents for immersion leaching have a boiling point in the range of 20°C to 90°C. Non-limiting examples of such solvents include tetrahydrofuran (THF), diethyl ether, hexane, acetone, ethanol, methanol, propanol, isopropanol, methyl ethyl ketone (MEK), and ethyl acetate. In embodiments of the present invention, the leaching solvent has a standard boiling point of 20°C to 90°C. In embodiments of the present invention, the leaching solvent has a standard boiling point of 20°C to 90°C, and the leaching temperature is at or near the boiling point. In embodiments of the present invention, the leaching solvent has a standard boiling point of 20°C to 90°C, the leaching temperature is at or near the boiling point, and the leaching pressure is near atmospheric pressure. In the case of such a leaching solvent, the pressure may be higher than atmospheric pressure. In embodiments of the present invention, the leaching solvent has a standard boiling point of 20°C to 90°C, and the leaching pressure is above atmospheric pressure to about 1,000 atm. The leaching solvent may have a boiling point higher than the leaching temperature. In embodiments of the present invention, the leaching solvent has a standard boiling point higher than the leaching temperature. In embodiments of the present invention, the leaching solvent is ethyl acetate, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is near atmospheric pressure to about 1,000 atm. In embodiments of the present invention, the leaching temperature is about 20°C to about 90°C, the leaching pressure is near atmospheric pressure to about 1,000 atm, the leaching solvent is ethyl acetate, the total residence time of the leaching process is less than about 360 minutes, and the average removal efficiency is about 55%. In embodiments of the present invention, the leaching solvent is hexane, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is near atmospheric pressure to about 1,000 atm.

[0153] Leaching solvents having a standard boiling point below the leaching temperature are also preferred because they have a high immersion leaching pressure. In the embodiments of the present invention, the leaching solvent has a standard boiling point below the leaching temperature. In the embodiments of the present invention, the leaching solvent is propane. In the embodiments of the present invention, the leaching solvent is propane, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is about 9 atm to about 1,000 atm. In the embodiments of the present invention, the leaching solvent is dimethyl ether (DME). In the embodiments of the present invention, the leaching solvent is DME, the leaching temperature is about 20°C to about 120°C, and the leaching pressure is about 6 atm to about 1,000 atm.

[0154] A leaching solvent is also preferred in which the standard boiling point is below the leaching temperature and the critical temperature is below the leaching temperature. In embodiments of the present invention, the leaching solvent has a standard boiling point below the leaching temperature and its critical temperature is below the leaching temperature. In embodiments of the present invention, the leaching solvent is ethane. In embodiments of the present invention, the leaching solvent is critical ethane or supercritical ethane. In embodiments of the present invention, the leaching solvent is ethane, the leaching temperature is about 31°C to about 120°C, and the leaching pressure is about 40 atm to about 1,000 atm. In embodiments of the present invention, the leaching solvent is CO2. In embodiments of the present invention, the leaching solvent is CO2, the leaching temperature is about 31°C to about 120°C, and the leaching pressure is about 68 atm to about 1,000 atm. In embodiments of the present invention, the leaching solvent is CO2 containing less than 5% by weight of water.

[0155] The density of the leaching solvent is preferably lower than the density of the recycled polymer under the temperature and pressure of the immersion leaching process. In the case of recycled polyethylene, the density of the leaching solvent under the temperature and pressure of the immersion leaching process is preferably less than about 0.90 g / mL, but a higher density may be used.

[0156] Preferred leaching solvents include those with a higher affinity for chemical contaminants than for the regenerated polymer. Solvents with a higher affinity for the target chemical contaminant in the regenerated polyolefin compared to their affinity for the polyolefin include, but are not limited to, diethyl ether, MEK, ethyl acetate, THF, acetone, methylene chloride, and methanol. Other oxygen-containing polar hydrocarbon solvents are also likely to have similar desired affinity. Solvents lacking such properties can also be used, but a higher solvent-to-polymer ratio may be required. Preferably, the solvent does not significantly dissolve the regenerated polymer under the temperature and pressure of the immersion leaching process (less than about 5% by weight may dissolve).

[0157] In embodiments of the present invention, the leaching solvent is an organic solvent or a mixture of organic solvents. In embodiments of the present invention, the leaching solvent is selected from the group comprising hydrocarbons. In embodiments of the present invention, the leaching solvent is selected from the group comprising aliphatic hydrocarbons. In embodiments of the present invention, the leaching solvent is selected from the group comprising aromatic hydrocarbons. In embodiments of the present invention, the leaching solvent is selected from the group comprising alkanes. In embodiments of the present invention, the leaching solvent is selected from the group comprising methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, hexane (n-hexane, isohexane, neohexane), heptane, octane, or mixtures thereof. In embodiments 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.

[0158] The temperature may be changed during the immersion leaching process, but is generally constant within a given stage of the unit operation. The pressure may be changed to alter the solubility of the leaching solvent in the regenerated polymer or to improve the solubility of chemical contaminants in the leaching solvent.

[0159] The immersion leaching process may be carried out in stages and may be combined with other types of additional leaching steps not discussed herein. The same applies to the liquid-liquid extraction process. In addition, the liquid-liquid extraction process may be combined with the immersion leaching process at various stages to form a given purification process. In embodiments of the present invention, the number of leaching steps is two or more. In embodiments of the present invention, the number of leaching steps is about 1 to about 50. In embodiments of the present invention, the number of leaching steps is about 2 to about 30. In embodiments of the present invention, the number of leaching steps is about 5 to about 20. In embodiments of the present invention, the number of liquid-liquid steps is two or more. In embodiments of the present invention, the number of leaching steps is two or more. In embodiments of the present invention, the number of liquid-liquid steps is one or more and the number of leaching steps is one or more.

[0160] A single stirred-tank reactor achieves a specific removal efficiency. Efficiency can be improved by having multiple stirred-tank reactors in series, where the recycled polymer from the first stage is primarily separated from the first-stage leaching solvent, and this first-stage plastic is used in the second stage with fresh leaching solvent. This is repeated for each additional stage. This method improves removal efficiency at the expense of additional reactors and complexity, but maintains overall time, yield, and solvent utilization. In practice, the number of reactor stages can be anywhere from 1 to about 10 in the case of a stirred-tank system. If more stages are required, a continuous counterflow method can be used.

[0161] While we do not wish to be bound by theory, the theoretical maximum contaminant removal capacity of an immersion leaching process is based on the thermodynamic equilibrium / distribution of chemical contaminants between the regenerated polymer and the leaching solvent at the temperature and pressure of the immersion leaching process. Thermodynamic equilibrium may not be achieved due to the dynamic limits in the immersion leaching process. This is true for the total immersion leaching process and for each individual immersion leaching stage. A higher leaching solvent to regenerated polymer mass ratio makes leaching thermodynamically and kinetically favorable at the expense of larger leaching solvent consumption and a larger leaching process size, which corresponds to greater costs. Therefore, a balance must be found between these critical design and operating variables for the removal efficiency of the selected chemical contaminants.

[0162] In general terms, the applicants have found that the total mass ratio of fresh or regenerated leaching solvent to regenerated polymer is preferably greater than about 5:1. In embodiments of the present invention, the total mass ratio of fresh or regenerated leaching solvent to regenerated polymer is greater than about 10:1. In embodiments of the present invention, the total mass ratio of fresh or regenerated leaching solvent to regenerated polymer is greater than about 15:1. In embodiments of the present invention, the total mass ratio of fresh or regenerated leaching solvent to regenerated polymer is greater than about 20:1. In embodiments of the present invention, the total mass ratio of fresh or regenerated leaching solvent to regenerated polymer is greater than about 30:1 and less than about 100:1.

[0163] If immersion leaching is completed in stepwise or continuous stages, the leaching solvent to regenerated polymer ratio per stage may be lower than the range described here (but still exceeding the minimum value of approximately 5:1 per stage), however, the total solvent used relative to the total regenerated polymer, represented by the sum of the solvents used in all stages, should be within this range. Furthermore, any contaminated solvent from any stage can be used "as is" as a solvent for another stage. Any contaminated solvent at any point in the process can be regenerated by known methods or combinations such as distillation, filtration, and ion exchange.

[0164] Another important kinetic contributing factor is the average surface area-to-volume ratio of the regenerated polymer in and exposed to the leaching solvent. Generally, the time required to extract chemical contaminants from the regenerated polymer is strongly related to the diffusion path length within the polymer. The diffusion path length is indirectly proportional to the average surface area-to-volume ratio of the geometric morphology of the regenerated polymer and its ability to access the surface area in the leaching solvent. Therefore, a higher average surface area-to-volume ratio results in shorter diffusion path lengths and faster diffusion dynamics. In immersion leaching processes, a high average surface area-to-volume ratio is a critical parameter for rapid and efficient removal of contaminants, both surface and bulk.

[0165] In the immersion leaching process, since the processing temperature is below the primary melting point, the average surface area-to-volume ratio of the recycled polymer in and exposed to the extraction solvent is essentially the same as the average surface area-to-volume ratio of the recycled polymer. For film-based recycled polymers, the immersion leaching process is ideal because they have a very high inherent average surface area-to-volume ratio. When recycled polymers are provided in other forms with lower average surface area-to-volume ratios, such as pellets, granulated bottles, or granulated components, 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, calendering, pressing, and stretching.

[0166] Known means for increasing effective mass transfer given a given surface area-to-volume ratio and a given set of conditions at the interface between the regenerated polymer and the leaching solvent include applying energy to the regenerated polymer, such as but not limited to vibrations in the form of ultrasonic energy and / or microwaves.

[0167] Following the immersion leaching process, the leached polymer can be deflated to remove the leaching solvent. The contaminated leaching solvent contains a small amount of dissolved regenerated polymer, leached contaminants, and pure leaching solvent. There are many methods to recover higher purity polymer and leaching solvent, independent of the leached contaminants.

[0168] In general, regardless of the process type or leaching solvent, small amounts of recycled polymer may dissolve in the leaching solvent. Low-MW waxes, in particular, tend to solubilize in the leaching solvent. These can cause problems in the recovery of the distillation base of the purified leaching solvent due to the accumulation of wax on the process equipment. Methods to reduce this tendency are known. One such method is to lower the temperature of the contaminated leaching solvent below the cloud point to precipitate the polymer or wax phase, followed by filtration. Unlike recycled polymers, residual plastics or waxes resulting from precipitation from contaminated solvents may contain significant contamination.

[0169] Distillation of contaminated leaching solvent may be used to regenerate the leaching solvent for reuse in various leaching operations. However, given the high volume of leaching solvent used in the present invention, distillation may not be economically viable on a continuous basis. Furthermore, since the chemical contaminants targeted by the present invention are extremely low in concentration, the concentration of these chemical contaminants in the contaminated leaching solvent may be correspondingly low or even lower. Therefore, a preferred method for purifying the contaminated leaching solvent is to directly remove the contaminants without volatilizing the bulk leaching solvent phase. Such methods include ion exchange and adsorption / absorption, for example, passing the contaminated leaching solvent through activated carbon, alumina, or a bed of activated alumina. This method can be used alone or in combination with distillation to achieve a suitable level of purification with appropriate energy consumption. Furthermore, the contaminated leaching solvent from any leaching stage can be used "as is" as a leaching solvent for another stage. The contaminated leaching solvent at any point in the process can be regenerated by known methods or combinations such as distillation, filtration, and ion exchange.

[0170] The leached polymer may contain a small amount of leaching solvent either physically adsorbed or bulk absorbed. The concentration of leaching solvent in the leached polymer can be reduced by defoliation techniques. In embodiments of the present invention, the leached polymer is defoliated until the content of leaching solvent in the leached polymer is less than 1% by weight.

[0171] A stirred-tank reactor operating at the boiling point of the leaching solvent offers improvements over existing methods. For example (Examples 1, 2, 3, and 4; and Tables 7, 8, 9, and 10), immersion leaching processes using ethyl acetate or THF provide a removal efficiency of over 88% of selected contaminants.

[0172] In embodiments of the present invention, the leaching solvent is ethyl acetate. In embodiments of the present invention, the leaching solvent is ethyl acetate, and the leaching pressure is near atmospheric pressure. In embodiments of the present invention (Example 1 and Table 7), the immersion leaching process is carried out in a stirred tank, the leaching temperature is approximately 77.1°C, the leaching pressure is near atmospheric pressure, and the leaching solvent contains ethyl acetate. In embodiments of the present invention, the immersion leaching process is carried out in a stirred tank, the leaching temperature is approximately 77.1°C, the leaching pressure is near atmospheric pressure, and the leaching solvent contains ethyl acetate, and the recycled polymer is approximately 80 mm -1 The surface area to volume ratio is as follows: there are 2 leaching stages, the mass ratio of ethyl acetate to recycled polymer per stage is approximately 18:1, the immersion leaching residence time per stage is approximately 50 minutes, the total mass ratio of ethyl acetate to recycled polymer is approximately 36:1, the total residence time is approximately 100 minutes, and the average reduction in concentration of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate is approximately 89%.

[0173] In embodiments of the present invention (Example 2 and Table 8), the immersion leaching process is carried out in a stirred tank, the leaching temperature is approximately 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent contains ethyl acetate, and the recycled polymer is approximately 80 mm -1The surface area to volume ratio is as follows: there are 2 leaching stages, the mass ratio of ethyl acetate to recycled polymer per stage is approximately 18:1, the immersion leaching residence time per stage is approximately 30 minutes, the total mass ratio of ethyl acetate to recycled polymer is approximately 36:1, the total residence time is approximately 60 minutes, and the average reduction in concentration of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate is approximately 89%.

[0174] In embodiments of the present invention, the leaching solvent is THF. In embodiments of the present invention, the leaching solvent is THF, and the leaching pressure is near atmospheric pressure. In embodiments of the present invention, immersion leaching is performed in a stirred tank, the leaching temperature is approximately 66°C, the leaching pressure is near atmospheric pressure, and the leaching solvent contains THF. In embodiments of the present invention (Example 3 and Table 9), the immersion leaching process is performed in a stirred tank, the number of leaching steps is 2, the leaching temperature is approximately 66°C, the leaching pressure is near atmospheric pressure, the leaching solvent contains THF, and the recycled polymer is approximately 80 mm -1 The surface area to volume ratio is as follows: the THF to regenerated polymer ratio is approximately 18:1 per step, the residence time for each leaching step is approximately 50 minutes, the total THF to regenerated polymer mass ratio is approximately 36:1, the total residence time for the immersion leaching process is approximately 100 minutes, and the average reduction in concentration of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate is approximately 90%.

[0175] In embodiments of the present invention, the leaching solvent is DME, the leaching temperature is approximately 70°C, and the leaching pressure is approximately 18 atm or greater. In embodiments of the present invention, the leaching solvent is DME, and the regenerated polymer is approximately 80 mm -1 It has a surface area-to-volume ratio, a leaching temperature of approximately 70°C, and a leaching pressure of over approximately 18 atm. In embodiments of the present invention, the leaching solvent is CO2, the leaching temperature is approximately 70°C, the leaching pressure is approximately 340 atm, and the recycled polymer is approximately 80 mm -1 It has a surface area to volume ratio.

[0176] Following the immersion leaching process, the leached polymer may be physically moistened with residual leaching solvent and may contain a small amount of absorbed leaching solvent. As discussed earlier, there are many methods for recovering the leached polymer and leaching solvent independently of the leached contaminants. The leached polymer can be dried and deflated by many known commercial means. One method is by cyclone drying. Another method is by melt extrusion with a deflation step. In embodiments of the present invention, the leached polymer is treated to reduce the amount of leaching solvent in the regenerated polymer to less than about 1% by weight. The contaminated leaching solvent can be washed away by known methods such as distillation, ion exchange, and filtration. The resulting deflated leached polymer may be used as is or further processed into other forms, including pellets, through various processes.

[0177] In embodiments of the present invention, the total residence time for the leaching process is less than approximately 600 minutes. In embodiments of the present invention, the total residence time for the leaching process is less than approximately 480 minutes. In embodiments of the present invention, the total residence time for the leaching process is less than approximately 360 minutes. In embodiments of the present invention, the total residence time for the leaching process is less than approximately 180 minutes. In embodiments of the present invention, the total residence time for the leaching process is less than approximately 60 minutes.

[0178] In embodiments of the present invention, the residence time for each leaching step is less than approximately 180 minutes. In embodiments of the present invention, the residence time for each leaching step is less than approximately 90 minutes. The residence time for each leaching step is less than approximately 60 minutes. In embodiments of the present invention, the residence time for each leaching step is less than approximately 30 minutes. In embodiments of the present invention, the residence time for each leaching step is about 20 minutes.

[0179] In embodiments of the present invention, a method for purifying a regenerated polymer comprises: a) obtaining a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, wherein the regenerated polymer contains contaminants, each contaminant having a concentration, and the regenerated polymer contaminants include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; and b) leaching from the regenerated polymer with alkylphenols, bisphenols, dioxins, PCBs, or phthalates at an average removal efficiency of over a total residence time and residence time of each leaching step using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to about 1,000 atm, to produce a leached polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, each having a concentration, and with an average removal efficiency of over 55%.

[0180] In embodiments of the present invention, the leaching process is carried out in a continuous stirred tank reactor (CSTR), the regenerated polymer is surface-cleaned in a non-densified state in a surface cleaning process before dissolution, the surface cleaning process results in a reduction of more than 80% of loosely bound surface contamination, and the regenerated polymer before surface cleaning is approximately 1 mm -1 The surface cleaning process has an average surface area-to-volume ratio of over 55%, and is a deinking type surface cleaning process. The deinking process results in a ΔE change of less than approximately 10% between the deinked polymer and the regenerated polymer that does not contain surface-printed ink. The leaching solvent is ethyl acetate, and the CSTR consists of three leaching stages. The leaching temperature is approximately 77°C, the leaching pressure is near atmospheric pressure, and the residence time for each leaching stage is approximately 20 minutes. The regenerated polymer is deflated and densified using melt extrusion to produce leached polymer pellets, and the average removal efficiency is over 55%.

[0181] In embodiments of the present invention, a method for purifying a regenerated polymer is to obtain a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the regenerated polymer contaminants containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, and b) obtaining 4-tert-pentylphenol from the regenerated polymer. The method involves leaching bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate in multiple leaching steps using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to about 1,000 atm, over a total residence time and the residence time of each leaching step, with an average removal efficiency, to produce an leached polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, each having a concentration greater than or equal to about 55%.

[0182] VII. Combination of surface purification process and immersion leaching process In general, the combination of surface purification and immersion leaching processes provides synergistic benefits in the overall removal of contamination. The surface purification process effectively removes both impermeable and permeable surface contamination, including chemical contaminants and chemical contaminant precursors. Therefore, surface purification reduces the burden on the immersion leaching process and makes it more effective. If the recycled polymer is heavily contaminated with surface contamination, such contamination is preferably removed first in the surface purification process, and then in the immersion leaching process. After the surface contamination has been removed in the surface purification process, any remaining bulk permeable contamination is removed in the immersion leaching process. The only contamination that is not significantly removed by this two-step approach is bulk impermeable contamination, such as heavy metals intentionally added during the manufacture of the original plastic part.

[0183] Preferred methods for surface cleaning have already been discussed in the section on surface purification. A more preferred method for surface cleaning is the deinking method, which is also described in the surface purification method (Comparative Example 3). This method removes not only surface contaminants such as dirt, but also surface-printed ink. This method is also very effective in removing paper labels, which are precursors to chemical contaminants. In this method, the regenerated polymer with the original surface area exposed is fed into a multi-stage aqueous cleaning process where surface contaminants, including surface-printed ink, dirt, grit, paper, adhesives, etc., are removed. The resulting material is then dried. The dried material may be further densified into pellets using extrusion, including defoliation and melt filtration. For the purposes of the present invention, the deinking method is any surface cleaning method that removes surface printing to a degree sufficient to result in a difference of less than 10% in ΔE (ΔE measured using Method 3 in Section IX) between the deinked regenerated polymer and the unprinted regenerated polymer.

[0184] For naming purposes, the surface-purified polymer obtained by feeding the regenerated polymer to a surface purification method is called the surface-cleaned polymer. The surface-cleaned polymer is then fed to a immersion leaching process, and the resulting polymer is called the leached polymer. The surface purification method may include multiple surface purification processes. The immersion leaching process may include multiple immersion leaching steps of various types. The removal efficiency of the combination of the surface purification and immersion leaching processes is calculated from the regenerated polymer concentration and the associated leached polymer. The combination of the surface cleaning and immersion leaching processes resulted in an average concentration reduction of approximately 95% for bisphenol A, 4-tert-pentylphenol, OCDD, PCB108, and di-2-ethylhexyl phthalate (Example 4 and Table 10).

[0185] In embodiments of the present invention, a method for purifying a regenerated polymer comprises: a) obtaining a regenerated polymer, the regenerated polymer being selected from the group consisting of PCR polymers, PIR polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) surface washing the regenerated polymer to produce a surface-washed polymer; and c) leaching the surface-washed polymer of alkylphenols, bisphenols, dioxins, PCBs, and phthalates with an average removal efficiency over a total residence time and residence time of each leaching step using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to about 1,000 atm, to produce a leached polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates, each having a concentration, with an average concentration reduction of more than 55%.

[0186] In embodiments of the present invention, the immersion leaching process is performed after surface cleaning. In embodiments of the present invention, the immersion leaching process is performed after the surface cleaning process, and the regenerated polymer is not densified before the surface cleaning process. In embodiments of the present invention, immersion leaching is performed after the surface cleaning process, and the regenerated polymer is not densified before the surface cleaning process, although the surface-cleaned regenerated polymer may be densified before the immersion leaching process.

[0187] In embodiments of the present invention, the immersion leaching process is performed using a leaching solvent under certain temperature and pressure, the immersion leaching process is carried out in multiple stages, and the regenerated polymer is partially purified using a surface cleaning process.

[0188] In embodiments of the present invention (Example 4 and Table 10), the surface cleaning process includes commercially available deinking with Cadel, resulting in a ΔE change of less than about 10% and removal of more than 80% of loosely bound surface contaminants; the immersion leaching process is carried out in a stirred tank, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent contains ethyl acetate, and the total residence time is about 60 minutes. In embodiments of the present invention, the surface cleaning includes commercially available deinking with Cadel, resulting in a ΔE change of less than about 10% and removal of more than 80% of loosely bound surface contaminants; the immersion leaching process is carried out in a stirred tank over two stages, the leaching temperature is about 77.1°C, the leaching pressure is near atmospheric pressure, the leaching solvent contains ethyl acetate, the residence time per stage is about 30 minutes, and the concentration reduction of OCDD is about 98%.

[0189] In embodiments of the present invention, the surface cleaning process includes any known surface cleaning method, the immersion leaching step uses a stirred tank, and the immersion leaching step uses a leaching solvent. In embodiments of the present invention, the immersion leaching step uses a stirred tank and includes a plurality of leaching steps.

[0190] In embodiments of the present invention, the regenerated polymer is surface-cleaned in a non-densified state in a surface cleaning step prior to the leaching step to produce a surface-cleaned polymer, the surface cleaning resulting in a reduction of more than 80% of loosely bound surface contamination, and the regenerated polymer before surface cleaning is approximately 1 mm -1 The surface cleaning process has an average surface area-to-volume ratio of over 55%, and is a deinking type surface cleaning process, which results in a ΔE change of less than 10% between the deinked polymer and the regenerated polymer that does not contain surface-printed ink. The leaching process is carried out in a continuous stirred tank reactor (CSTR), the leaching solvent is ethyl acetate, the CSTR consists of three leaching stages, the leaching temperature is about 77°C, the leaching pressure is near atmospheric pressure, the residence time of each leaching stage is about 20 minutes, the average removal efficiency is over 55%, and the leached polymer is deflated and densified using melt extrusion to produce leached polymer pellets.

[0191] In embodiments of the present invention, a method for purifying a regenerated polymer is to a) obtain a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, and b) surface-wash the regenerated polymer in a non-densified state to produce a surface-washed polymer, the surface washing being low in the amount of loosely bound surface contaminants, more than 80% The process involves producing, and a) leaching from the regenerated polymer for 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate in multiple leaching steps over a total residence time and a residence time for each leaching step, at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to about 1,000 atm, with an average removal efficiency, to produce an leached polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, each having a concentration greater than or equal to 55%.

[0192] VIII. Purification of the leached polymer Surprisingly, it was found that the leached polymer in the high MW polymer solution could be purified by filtration. This process, illustrated in Figures 1A and 1B, comprises: 1) dissolving the leached polymer in a fluid solvent at its dissolution temperature and pressure to produce a first solution containing the dissolved polymer (step c in Figure 1A and step d in Figure 1B); 2) precipitating the first solution at a certain temperature and pressure to produce a second solution containing the precipitated polymer (step d in Figure 1A and step e in Figure 1B); 3) filtering the second solution by mechanical filtration at a certain temperature and pressure to produce a third solution containing the filtered polymer, and filtering the third solution by adsorption filtration at a certain temperature and pressure to produce a fourth solution containing the twice filtered polymer (steps e and f in Figure 1A, and steps f and g in Figure 1B); and 4) separating the twice filtered polymer from the fourth solution to produce a higher purity polymer (step g in Figure 1A and step h in Figure 1B). Please note that the temperature and pressure values ​​mentioned above may vary from step to step. A schematic diagram of the experimental apparatus used in the dissolution, precipitation, filtration, and separation steps is shown in Figure 3.

[0193] In embodiments of the present invention, the higher purity polymer can be derived from a PCR flow and is essentially free of contaminants, pigments, odorless, homogeneous, and possesses properties similar to those of non-recycled polymers.

[0194] Fluid solvent In embodiments of the present invention, the fluid solvent has a standard boiling point below about 70°C. In embodiments of the present invention, the fluid solvent has standard boiling points below about 70°C and above about -45°C. In yet another embodiment, the fluid solvent has standard boiling points below about 70°C and above about -45°C, as well as a standard enthalpy of vaporization below about +25 kJ / mol. Pressurization maintains the solvent having a standard boiling point below the operating temperature range of the present invention in a state that produces little to no solvent vapor.

[0195] In embodiments of the present invention, the fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof. In embodiments of the present invention, the aliphatic hydrocarbon of the fluid solvent is selected from the group consisting of C1-C6 aliphatic hydrocarbons and mixtures thereof. In embodiments of the present invention, the fluid solvent includes n-butane, butane isomers, or mixtures thereof.

[0196] In embodiments of the present invention, the fluid solvent having a standard boiling point below about 70°C is selected from the group consisting of carbon dioxide, ketones, alcohols, ethers, esters, alkenes, alkanes, and mixtures thereof. Non-limiting examples of fluid solvents having a standard boiling point below about 70°C include carbon dioxide, acetone, methanol, dimethyl ether, diethyl ether, ethyl methyl ether, tetrahydrofuran, methyl acetate, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, branched isomers of pentene, 1-hexene, 2-hexene, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane isomers, and other substances that may be apparent to those skilled in the art.

[0197] The selection of a suitable fluid solvent or solvent mixture will depend on the polymer or polymer mixture to be purified by the present invention. Furthermore, the selection of the polymer to be purified and the corresponding fluid solvent used will determine the temperature and pressure range used to carry out the process of the present invention. An overview of the polymer phase behavior in the types of fluid solvents described in the present invention is provided in the following reference: McHugh et al. (1999) Chem. Rev. 99: 565-602.

[0198] Dissolution In embodiments of the present invention, a method for purifying a regenerated polymer includes dissolving the leached polymer in a fluid solvent under a temperature and pressure at which the polymer dissolves in the fluid solvent. While not theoretically bound, the applicants believe that the temperature and pressure can be controlled in a manner that achieves thermodynamically favorable dissolution of the regenerated polymer in the fluid solvent. Furthermore, the temperature and pressure can be controlled in a manner that allows the dissolution of a specific polymer or polymer mixture while preventing the dissolution of other polymers or polymer mixtures. This controllable dissolution enables the separation of polymers from polymer mixtures.

[0199] In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polymer in a fluid solvent that does not dissolve contaminants under the same temperature and pressure conditions. These contaminants may include pigments, fillers, stains, and other polymers. These contaminants are released from the leached polymer during dissolution and subsequently removed from the polymer solution by a subsequent solid-liquid separation step.

[0200] In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polyethylene in a fluid solvent at a temperature and pressure at which polyethylene dissolves in the fluid solvent. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polymer in a fluid solvent at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polymer in a fluid solvent at a temperature of about 110°C to about 220°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polymer in a fluid solvent at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polymer in a fluid solvent at a pressure of about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0201] In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polyethylene in n-butane at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polyethylene in n-butane at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polyethylene in n-butane at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polyethylene in n-butane under a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polyethylene in n-butane under a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-butane under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0202] In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-butane at a mass percent concentration of at least 0.5%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-butane at a mass percent concentration of up to 20%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 12%.

[0203] In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in propane at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in propane at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in propane at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane under a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0204] In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane at a mass percent concentration of at least 0.5%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polyethylene in n-pentane at a mass percent concentration of up to 20%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the leached polyethylene is dissolved at a mass percent concentration of up to 12%.

[0205] In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in a fluid solvent at a temperature and pressure at which polypropylene dissolves in the fluid solvent. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in n-butane at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in n-butane at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in n-butane at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in n-butane at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in n-butane under a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polypropylene in n-butane under a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0206] In embodiments of the present invention, a method for purifying the leached polymer includes dissolving the leached polypropylene in n-butane at a mass percent concentration of at least 0.5%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying the leached polymer includes dissolving the leached polypropylene in n-butane at a mass percent concentration of up to 20%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 12%.

[0207] In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polypropylene in propane at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polypropylene in propane at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polypropylene in propane at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polypropylene in propane at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a leached polymer includes dissolving the leached polypropylene in propane at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present invention, a method for purifying the leached polymer includes dissolving the leached polypropylene in propane under a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0208] In embodiments of the present invention, a method for purifying the leached polymer includes dissolving the leached polypropylene in propane at a mass percent concentration of at least 0.5%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying the leached polymer includes dissolving the leached polypropylene in propane at a mass percent concentration of up to 20%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the leached polypropylene is dissolved at a mass percent concentration of up to 12%.

[0209] In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in a fluid solvent at a temperature and pressure such that the leached polystyrene dissolves in the fluid solvent. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in n-butane at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in n-butane at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in n-butane at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in n-butane at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in n-butane under a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached polystyrene in n-butane under a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0210] In embodiments of the present invention, a method for purifying leached polystyrene includes dissolving the leached polystyrene in n-butane at a mass percent concentration of at least 0.5%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying leached polystyrene includes dissolving the leached polystyrene in n-butane at a mass percent concentration of up to 20%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the leached polystyrene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the leached polystyrene is dissolved at a maximum mass percentage concentration of 12%.

[0211] In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in a fluid solvent at a temperature and pressure such that the leached poly(dimethylsiloxane) dissolves in the fluid solvent. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 115°C to about 280°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 120°C to about 220°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a temperature of about 140°C to about 180°C. In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane at a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane under a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In embodiments of the present invention, a method for purifying an leached polymer includes dissolving the leached poly(dimethylsiloxane) in n-butane under a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0212] In embodiments of the present invention, a method for purifying leached poly(dimethylsiloxane) includes dissolving the leached poly(dimethylsiloxane) in n-butane at a mass percent concentration of at least 0.5%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying leached poly(dimethylsiloxane) includes dissolving the leached poly(dimethylsiloxane) in n-butane at a mass percent concentration of up to 20%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 18%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 16%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 14%. In embodiments of the present invention, the leached poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 12%.

[0213] In embodiments of the present invention, a method for purifying a regenerated polymer includes dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa), thereby producing a first solution comprising the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant.

[0214] In embodiments of the present invention, the leached polymer is dissolved in a fluid solvent or a fluid solvent mixture at a mass percentage concentration of at least 0.5%. In embodiments of the present invention, the temperature during the dissolution process is about 110°C to about 220°C. In embodiments of the present invention, the pressure during the dissolution process is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0215] Precipitation In embodiments of the present invention, a method for purifying a polymer includes separating undissolved contaminants from a polymer solution via a precipitation step at a temperature and pressure in which the polymer remains dissolved in a fluid solvent. In embodiments of the present invention, the precipitation step involves applying a force to the undissolved contaminants to move them uniformly in the direction of the force. Typically, the applied precipitation force is gravity, but may be centrifugal force, centripetal force, or any other force. The amount of force applied and the duration of the precipitation time will depend on several parameters, including, but not limited to, the particle size of the contaminant particles, the density of the contaminant particles, the density of the fluid or solution, and the viscosity of the fluid or solution. The following formula:

[0216]

number

[0217] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / fluid solvent solution at a temperature and pressure in which the polyethylene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / fluid solvent solution at a temperature of about 110°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / fluid solvent solution at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / fluid solvent solution at a pressure of about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0218] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution at a pressure of about 4,000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0219] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

[0220] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution at a pressure of about 800 psig (5.52 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution under a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

[0221] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polyethylene / n-pentane solution in which polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

[0222] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / fluid solvent solution at a temperature and pressure in which the polypropylene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution under a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0223] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 12%.

[0224] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution under a pressure of approximately 3,500 psig (24.13 MPa) to approximately 5,000 psig (34.47 MPa).

[0225] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 12%.

[0226] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / fluid solvent solution at a temperature and pressure in which the polystyrene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0227] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution in which polystyrene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a polystyrene / n-butane solution in which polystyrene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polystyrene is dissolved at a maximum mass percentage concentration of 12%.

[0228] In embodiments of the present invention, a method for purifying a regenerated polymer includes precipitating contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure such that the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a regenerated polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution containing a solid medium under a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0229] In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes precipitating contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 18%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 16%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 14%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 12%.

[0230] In embodiments of the present invention, a method for purifying a regenerated polymer includes precipitating a first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution containing the precipitated polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant.

[0231] In embodiments of the present invention, the temperature during the sedimentation process is approximately 110°C to approximately 220°C. In embodiments of the present invention, the pressure during the sedimentation process is approximately 400 psig (2.76 MPa) to approximately 2,600 psig (17.93 MPa).

[0232] mechanical filtration For the purposes of this invention, unless otherwise specified, the term "filtration" refers to "mechanical filtration" or "adsorption filtration," or the term encompasses both types of filtration. A typical filtration system comprises a filter medium, a filter container, a filter inlet, and a filter outlet. The filter medium comprises filter particles contained within the filter container. The filter inlet is in fluid communication with the filter container and carries the filtration feed flow within the filter container, while the filter outlet is in fluid communication with the filtration system and discharges the filtrate flow from the filter container. A filtration system may comprise one or more filter media, a filter container, and filter inlets and outlets in series or parallel. Furthermore, a filtration system may operate in radial or axial flow, or in upflow, downflow, or crossflow. A non-limiting example of a radial flow filter is a candle filter. Moreover, filtration may be of the depth filtration type or the surface filtration type, and is based on a mechanical mode of operation. A non-limiting example of a mechanical mode of action is particle size exclusion, where the size of suspended (dispersed) contaminants is larger than the pores of the filter media, so the suspended (dispersed) contaminants are retained by the filter media and separated from the filtration feed flow. As described, particle size exclusion is an interparticle phenomenon.

[0233] The filter media used in depth filtration comprises aggregates of filter particles, which may be homogeneous or heterogeneous. The distribution of the filter particles within the filter media can be uniform or heterogeneous (e.g., multiple layers of different filter particles). The filter particles forming the filter media do not need to be identical in shape or size and may be provided in either a separate or interconnected configuration. For example, the filter media may include filter particles that are loosely associated or partially or entirely bound together by a polymer binder or other means for forming a monolithic structure.

[0234] Furthermore, filter particles may be provided in a variety of shapes and sizes. For example, but not limited to, filter particles may be provided in simple forms such as powders, granules, fibers, and beads. Filter particles can be provided in spherical, polyhedral, and cylindrical shapes, as well as other symmetrical, asymmetrical, and irregular shapes. In addition, filter particles can also be formed into complex forms such as webs, screens, meshes, nonwovens, wovens, and bonded blocks, which may or may not be formed from the simple forms described above. The size of filter particles can vary from intangible filter particles (e.g., very fine powder) to filter particles with a shape that can be felt by touch. Furthermore, the size of the filter particles does not need to be uniform among the filter particles used in any single filtration system. In practice, it may be desirable to provide filter particles of different sizes in a single filter.

[0235] In embodiments of the present invention, the size of the filter particles varies from about 0.1 mm to about 10 mm. In embodiments of the present invention, the size of the filter particles varies from about 10 mm to about 8 mm. In embodiments of the present invention, the size of the filter particles varies from about 100 mm to about 5 mm. In embodiments of the present invention, the size of the filter particles varies from about 1 mm to about 4 mm. In embodiments of the present invention, the size of the filter particles varies between about 10 μm and about 100 μm. For spherical and cylindrical particles (e.g., fibers, beads, etc.), the above dimensions refer to the diameter of the filter particles. For filter particles having substantially different shapes, the above dimensions refer to the maximum dimensions (e.g., length, width, or height).

[0236] Non-limiting examples of filter particles include silicon dioxide (silica), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, amorphous volcanic glass, recycled glass, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, fuller's earth, bentonite clay, metal organic framework (MOF), covalent organic framework (COF), zeolitic imidazolate framework (ZIF), cellulose, lignocellulose, anthracite, carbon black, coke, and activated carbon. In embodiments of the present invention, the filter particles are selected from the group consisting of silica, activated alumina, silica gel, volcanic glass, fuller's earth, bentonite clay, and mixtures thereof. In embodiments of the present invention, the filter particles are selected from the group consisting of activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In embodiments of the present invention, the filter particles are selected from the group consisting of MOF, COF, ZIF, activated carbon, activated alumina, and mixtures thereof. In embodiments of the present invention, the filter particles are selected from the group consisting of diatomaceous earth, activated alumina, and mixtures thereof.

[0237] Non-limiting examples of filter media used in surface filtration include thin layers of filter particles, porous ceramics, filter paper, filter cloth, plastic membranes, screens, nonwoven fabrics, woven fabrics, porous frit / sintered metals, and perforated plates. In typical surface filtration, retained contaminants form a cake on the filter media, increasing in thickness as filtration progresses. Typically, the filter cake leads to an unsustainable pressure drop, and after a certain filtration time, the filter cake must be removed by either mechanical action or backflushing. In embodiments of the present invention, the filter media used in surface filtration is selected from the group consisting of thin layers of diatomaceous earth particles (typically called socks) deposited on a porous woven metal core. The porous core supports the filter media while allowing the filtration feed flow to pass through. Non-limiting examples of the core include perforated tubes and screen sleeves.

[0238] Filter aids may be used in filtration. Non-limiting examples of filter aids include diatomaceous earth (also known as Kieserugul), cellulose, and perlite. These filter aids can be used either as a precoat on the filter media or added to the filter feed stream. In the latter case (also known as body feed), the filter aid increases the porosity of the cake formed on the filter media, thereby reducing the pressure drop as the cake passes through during filtration.

[0239] When a filter reaches the end of its service life, it can be removed from the operation and replaced with a new one, or it can be regenerated. Non-exclusive examples of regeneration include backflushing, thermal regeneration, and solvent regeneration.

[0240] In embodiments of the present invention, the surface filter includes a candle filter. In embodiments of the present invention, the candle filter includes a thin layer of diatomaceous earth deposited on a woven metal porous core. In embodiments of the present invention, the thickness of the diatomaceous earth layer is about 1 mm to about 20 mm. In embodiments of the present invention, the thickness of the diatomaceous earth layer is about 2 mm to about 10 mm. In embodiments of the present invention, the thickness of the diatomaceous earth layer is about 3 mm to about 5 mm.

[0241] The permeability of a filter medium is measured (as is well known to those skilled in the art) by passing a fluid flow through the filter medium and measuring the flow rate and pressure drop. The unit of measurement is millidarcy (mD), where 1 mD is equivalent to the passage of 1 mL of fluid with a viscosity of 1 mPa·s (1 cP) in 1 second under a pressure of 1 atmosphere, over a cross-sectional area of ​​1 cm². 2 This corresponds to passing through a filter medium with a thickness of 1 cm. In embodiments of the present invention, the permeability of the diatomaceous earth filter medium is approximately 30 mD to approximately 20,000 mD. In embodiments of the present invention, the permeability of the diatomaceous earth filter medium is approximately 400 mD to approximately 8,000 mD. In embodiments of the present invention, the permeability of the diatomaceous earth filter medium is approximately 1,000 mD to approximately 4,000 mD. In embodiments of the present invention, the permeability of the diatomaceous earth filter medium is approximately 2,300 mD to approximately 3,400 mD.

[0242] In embodiments of the present invention, the diatomaceous earth filter material holds suspended particles having a diameter greater than approximately 0.3 μm. In embodiments of the present invention, the diatomaceous earth filter material holds suspended particles having a diameter greater than approximately 0.8 μm. In embodiments of the present invention, the diatomaceous earth filter material holds suspended particles having a diameter greater than approximately 1 μm. In embodiments of the present invention, the diatomaceous earth filter material holds suspended particles having a diameter greater than approximately 1.7 μm. In embodiments of the present invention, the diatomaceous earth filter material holds suspended particles having a diameter greater than approximately 4 μm.

[0243] In embodiments of the present invention, the candle filter includes a thin diatomaceous earth filter material deposited on a woven metal core, the thickness of which is about 2 mm to about 10 mm, the permeability of which is about 2,300 mD to 3,400 mD, and which holds suspended particles having a diameter greater than about 1.7 μm.

[0244] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / fluid solvent solution under a temperature and pressure in which the polyethylene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / fluid solvent solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, the temperature in the filtration step is about 110°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / fluid solvent solution at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, the pressure in the filtration step is about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0245] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0246] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

[0247] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polyethylene / n-pentane solution under a pressure of about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

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

[0249] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution at a pressure of about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

[0250] In an embodiment of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution in which polypropylene is dissolved at a mass percent concentration of at least 0.5%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In an embodiment of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In an embodiment of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / n-butane solution in which 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%.

[0251] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution under a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0252] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polypropylene / propane solution in which polypropylene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 12%.

[0253] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / fluid solvent solution at a temperature and pressure in which the polystyrene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution under a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution under a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0254] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution in which polystyrene is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a polystyrene / n-butane solution in which polystyrene is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polystyrene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polystyrene is dissolved at a maximum mass percentage concentration of 12%.

[0255] In embodiments of the present invention, a method for purifying a regenerated polymer includes filtering contaminants from a poly(dimethylsiloxane) / fluid solvent solution at a temperature and pressure such that the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a regenerated polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 115°C to about 280°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 120°C to about 220°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution at a temperature of about 140°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0256] In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes filtering contaminants from a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 18%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 16%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 14%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 12%.

[0257] In embodiments of the present invention, a method for purifying a regenerated polymer is to obtain a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; b) leaching from the regenerated polymer with an average removal efficiency of alkylphenols, bisphenols, dioxins, PCBs, or phthalates using a leaching solvent in multiple leaching stages over a total residence time and the residence time of each leaching stage at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to about 1,000 atm, to produce a leached polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, each having a concentration, with an average removal efficiency of more than 55%; and c) leaching d) Dissolving the 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 approximately 90°C to approximately 280°C and a pressure of approximately 200 psig (1.38 MPa) to approximately 9,000 psig (62.05 MPa) to produce a first solution containing the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; and d) Dissolving the first solution at a temperature of approximately 90°C to approximately 280°C and a pressure of approximately 200 psig (1.38 MPa) to approximately 9,000 psig (62.05 MPa) e) Precipitating under a pressure of Pa) to produce a second solution containing the precipitated polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant; and e) filtering the second solution by mechanical filtration at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a third solution containing the filtered polymer, at least one dissolved contaminant, and an even smaller amount of at least one suspended contaminant.

[0258] In embodiments of the present invention, a method for purifying a regenerated polymer is to a) obtain a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, and b) obtain a non-high density regenerated polymer The process involves surface cleaning in a conditioned state to produce a surface-cleaned polymer, the surface cleaning resulting in a reduction of more than 80% of loosely bound surface contamination, and c) leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate from the regenerated polymer with average removal efficiency, using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to approximately 1,000 atm, over multiple leaching stages, over the total residence time and the residence time of each leaching stage, with each having a concentration. d) producing an leached polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, with an average removal efficiency of more than 55%, and d) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa), thereby dissolving the polymer, a) producing a first solution containing at least one dissolved contaminant and at least one suspended contaminant, and f) precipitating the first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution containing the precipitated polymer, at least one dissolved contaminant and a smaller amount of at least one suspended contaminant, and f) precipitating the second solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa).The process includes filtering by mechanical filtration under a pressure of 0.5 MPa to produce a third solution containing the filtered polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant.

[0259] Adsorption filtration In embodiments of the present invention, a method for purifying polyethylene includes contacting a contaminated polymer solution with a solid medium at a temperature and pressure such that the polymer remains dissolved in the fluid solvent. The solid medium of the present invention, also referred to throughout the invention as an adsorption medium or adsorption filter, is any solid material comprising solid medium particles and removing at least a portion of the contaminants from a solution of recycled polyethylene dissolved in the fluid solvent of the present invention. While not bound by theory, the applicants believe that this solid medium removes contaminants by a variety of mechanisms. Non-limiting examples of possible mechanisms include adsorption, absorption, electrostatics, particle size exclusion, ion exclusion, ion exchange, and other mechanisms that may be apparent to those skilled in the art. Furthermore, pigments and other contaminants commonly found in recycled polyethylene may be polar compounds or may have polar compounds on their surface, and therefore may preferentially interact with the solid medium (which may also have at least slight polarity). This polar-polar interaction is particularly preferred when a non-polar solvent (e.g., alkanes) is used as the fluid solvent.

[0260] In embodiments of the present invention, the solid medium is selected from the group consisting of inorganic substances, carbon-based substances, or mixtures thereof. Useful examples of inorganic substances include silicon oxides, aluminum oxides, iron oxides, aluminum silicate, magnesium silicate, amorphous volcanic glass, silica, silica gel, diatomaceous earth, sand, quartz, recycled glass, alumina, perlite, fuller's earth, bentonite, and mixtures thereof. Useful examples of carbon-based substances include anthracite, carbon black, coke, activated carbon, cellulose, and mixtures thereof. In embodiments of the present invention, the solid medium is recycled glass. In embodiments of the present invention, the solid medium particles are selected from the group consisting of silicon oxide (silica), silica gel, aluminum oxide (alumina), activated alumina, iron oxide, aluminum silicate, magnesium silicate, sand, quartz, diatomaceous earth, zeolite, molecular sieve, perlite, clay, fuller's earth, bentonite clay, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), zeolite imidazolate frameworks (ZIFs), cellulose, and lignocellulose. In embodiments of the present invention, the solid medium is selected from the group consisting of silica, activated alumina, silica gel, fuller's earth, bentonite clay, and mixtures thereof. In embodiments of the present invention, the solid medium is selected from the group consisting of activated carbon, activated alumina, diatomaceous earth, and mixtures thereof. In embodiments of the present invention, the solid medium is selected from the group consisting of MOFs, COFs, ZIFs, activated carbon, activated alumina, and mixtures thereof. In embodiments of the present invention, the solid medium is selected from the group consisting of diatomaceous earth, activated alumina, and mixtures thereof.

[0261] A non-limiting example of a physical mode of action is physical adsorption (also called physicoadsorption), in which dissolved contaminants are adsorbed onto the outer surface or inner surface of the pores of filter particles by van der Waals forces and separated from the filter feed flow. Another non-limiting example of a physical mode of action is electrostatic adsorption, in which suspended contaminants are adsorbed onto the surface of filter particles by electrostatic attraction. Filter particles and filter media that remove contaminants primarily by adsorption are called adsorption filter particles and adsorption filter media, respectively.

[0262] The adsorption filter media is typically housed in a cylindrical filter container as either a free medium or a bound block, and the adsorption filtration can be either axial or radial. The cylindrical adsorption filter media has an aspect ratio defined as the ratio of the height to the diameter of the cylindrical adsorption filter media. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 1 or more. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 2 or more. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 5 or more. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 10 or more. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 30 or more. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 50 or more. In embodiments of the present invention, the aspect ratio of the cylindrical adsorption filter media is about 70 or more.

[0263] In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 5 cm or more. In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 20 cm or more. In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 50 cm or more. In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 1 m or more. In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 1.5 m or more. In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 3 m or more. In embodiments of the present invention, the height of the cylindrical adsorption filter material is approximately 6 m or more.

[0264] In an embodiment of the present invention, the adsorption filter medium is cylindrical in shape, the filter medium contains free adsorption filter particles, the height of the cylindrical adsorption medium is approximately 122 cm, the diameter of the cylindrical adsorption medium is approximately 1.7 cm, the adsorption filter particles contain activated alumina, and the particle size of the adsorption filter particles is 7 × 14 mesh.

[0265] In embodiments of the present invention, the solid medium is brought into contact with the polymer for a predetermined time while being stirred in a container. In embodiments of the present invention, the solid medium is removed from the higher purity polymer solution via a solid-liquid separation step. Non-limiting examples of the solid-liquid separation step include filtration, decantation, centrifugation, and precipitation. In embodiments of the present invention, the contaminated polymer solution is passed through a fixed bed of the solid medium. In embodiments of the present invention, the solid medium is replaced as needed to maintain the desired purity of the polymer. In embodiments of the present invention, the solid medium is regenerated and reused in a purification step. In embodiments of the present invention, the solid medium is regenerated by fluidizing the solid medium during a rewashing step.

[0266] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a temperature and pressure in which the polyethylene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a temperature of about 110°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / fluid solvent solution with a solid medium at a pressure of about 400 psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

[0267] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4000 psig (27.58 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium at a pressure of about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution with a solid medium under a pressure of about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa).

[0268] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5% with a solid medium. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-butane solution in which polyethylene is dissolved at a mass percent concentration of up to 20% with a solid medium. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

[0269] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution with a solid medium at a pressure of about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution with a solid medium under a pressure of approximately psig (31.03 MPa) to approximately 6,000 psig (41.37 MPa).

[0270] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution in which polyethylene is dissolved at a mass percent concentration of at least 0.5% with a solid medium. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polyethylene / n-pentane solution in which polyethylene is dissolved at a mass percent concentration of up to 20% with a solid medium. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polyethylene is dissolved at a mass percent concentration of up to 12%.

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

[0272] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / n-butane solution in which polypropylene is dissolved at a mass percent concentration of at least 0.5% with a solid medium. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / n-butane solution in which polypropylene is dissolved at a mass percent concentration of up to 20% with a solid medium. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the polypropylene is dissolved at a mass percent concentration of up to 12%.

[0273] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution with a solid medium at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution with a solid medium at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution with a solid medium at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution with a solid medium at a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution with a solid medium at a pressure of about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution with a solid medium under a pressure of about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa).

[0274] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution in which polypropylene is dissolved at a mass percent concentration of at least 0.5% with a solid medium. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polypropylene / propane solution in which polypropylene is dissolved at a mass percent concentration of up to 20% with a solid medium. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, polypropylene is dissolved at a mass percent concentration of up to 12%.

[0275] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / fluid solvent solution with a solid medium at a temperature and pressure in which the polystyrene remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 90°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 100°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution with a solid medium at a pressure of about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution with a solid medium under a pressure of about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution with a solid medium under a pressure of about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa).

[0276] In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution in which polystyrene is dissolved at a mass percent concentration of at least 0.5% with a solid medium. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a recycled polymer includes contacting a polystyrene / n-butane solution in which polystyrene is dissolved at a mass percent concentration of up to 20% with a solid medium. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 18%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 16%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 14%. In embodiments of the present invention, the polystyrene is dissolved at a mass percent concentration of up to 12%.

[0277] In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / fluid solvent solution with a solid medium at a temperature and pressure such that the poly(dimethylsiloxane) remains dissolved in the fluid solvent. In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 115°C to about 280°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 120°C to about 220°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium at a temperature of about 140°C to about 180°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium under a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium under a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution with a solid medium under a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa).

[0278] In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 0.5% with a solid medium. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In embodiments of the present invention, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane) / n-butane solution in which poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 20% with a solid medium. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 18%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 16%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 14%. In embodiments of the present invention, poly(dimethylsiloxane) is dissolved at a maximum mass percentage concentration of 12%.

[0279] Embodiments of the present invention disclose a method for purifying a regenerated polymer. The method comprises: a) obtaining a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates; and b) removing alkylphenols, bisphenols, dioxins, PCBs, or phthalates from the regenerated polymer by mean removal. a) The process involves leaching the regenerated polymer in multiple leaching stages using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and at a pressure near atmospheric pressure to about 1,000 atm, over a total residence time and the residence time of each leaching stage, to produce leached polymers containing at least one of alkylphenols, bisphenols, dioxins, PCBs, or phthalates, each with a concentration greater than 55%, and a) the leached polymers at a temperature of about 90°C to about 280°C and about 200 psig (1.38 MP). a) Dissolve the polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, under a pressure of approximately 9,000 psig (62.05 MPa) to produce a first solution containing the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant; and d) Precipitate the first solution at a temperature of approximately 90°C to approximately 280°C and a pressure of approximately 200 psig (1.38 MPa) to approximately 9,000 psig (62.05 MPa) to obtain the precipitated polymer, at least one dissolved contaminant, and a smaller amount a) producing a second solution containing 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 containing the filtered polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant, and f) filtering the third 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).The process includes filtering the solution by adsorption filtration under a pressure of 0.5 MPa to produce a fourth solution containing the polymer that has been filtered twice.

[0280] Embodiments of the present invention disclose a method for purifying a regenerated polymer. The method comprises: a) obtaining a regenerated polymer, the regenerated polymer being selected from the group consisting of consumer post-use regenerated (PCR) polymers, industrial post-use regenerated (PIR) polymers, and combinations thereof, the regenerated polymer containing contaminants, each contaminant having a concentration, and the contaminants of the regenerated polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate; and b) surface-washing the regenerated polymer in a non-densified state to obtain the surface-washed polymer. The process involves generating a polymer, and surface cleaning results in a reduction of over 80% of loosely bound surface contamination. The process involves generating and, from the regenerated polymer, leaching 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate in multiple leaching stages using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure near atmospheric pressure to approximately 1,000 atm, over the total residence time and the residence time of each leaching stage, with an average removal efficiency, thereby removing 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate. The method involves producing an leached polymer containing at least one of ethylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, with an average removal efficiency of over 55%, and d) dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa), thereby dissolving the polymer, at least one dissolved substance. a) producing a first solution containing contaminants and at least one suspended contaminant, and f) precipitating the first solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solution containing precipitated polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant, and f) precipitating the second solution at a temperature of about 90°C to about 280°C and a pressure of about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa).The method comprises: g) filtering the polymer by mechanical filtration under a pressure of 0.5 MPa to produce a third solution containing filtered polymer, at least one dissolved contaminant, and a smaller amount of at least one suspended contaminant; and g) filtering the third solution by adsorption filtration by contacting it with one or more solid media at a temperature of approximately 90°C to approximately 280°C and a pressure of approximately 200 psig (1.38 MPa) to approximately 9,000 psig (62.05 MPa) to produce a fourth solution containing the polymer filtered twice.

[0281] In embodiments of the present invention, the temperature in the dissolution step, precipitation step, and filtration step is approximately 110°C to approximately 220°C. In embodiments of the present invention, the pressure in the dissolution step, precipitation step, and filtration step is approximately 400 psig (2.76 MPa) to approximately 2,600 psig (17.93 MPa).

[0282] separation In embodiments of the present invention, a method for purifying a recycled polymer includes separating a higher-purity polymer from a fluid solvent under a temperature and pressure at which the polymer precipitates from the solution and no longer dissolves in the fluid solvent. In embodiments of the present invention, precipitation of the higher-purity polymer from the fluid solvent is achieved by lowering the pressure under a fixed temperature. In embodiments of the present invention, precipitation of the higher-purity polymer from the fluid solvent is achieved by lowering the temperature under a fixed pressure. In embodiments of the present invention, precipitation of the higher-purity polymer from the fluid solvent is achieved by raising the temperature under a fixed pressure. In embodiments of the present invention, precipitation of the higher-purity polymer from the fluid solvent is achieved by lowering both the temperature and pressure. The solvent can be partially or completely converted from a liquid to a vapor phase by controlling the temperature and pressure. In embodiments of the present invention, by controlling the temperature and pressure of the solvent during the separation step, the precipitated polymer is separated from the fluid solvent without completely converting the fluid solvent to 100% vapor phase. Separation of the precipitated, higher-purity polymer is achieved by any method of liquid-liquid separation or liquid-solid separation. Non-limiting examples of liquid-liquid separation or liquid-solid separation include filtration, decantation, centrifugation, and precipitation.

[0283] In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / fluid solvent solution under temperatures and pressures at which polyethylene precipitates from the solution. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-butane solution at temperatures between approximately 0°C and approximately 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-butane solution at temperatures between approximately 50°C and approximately 175°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-butane solution at temperatures between approximately 100°C and approximately 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-butane solution at pressures between approximately 0 psig (0 MPa) and approximately 4,000 psig (27.58 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-butane solution under a pressure of about 50 psig (0.34 MPa) to about 2,000 psig (13.79 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-butane solution under a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0284] In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-pentane solution at a temperature of about 0°C to about 280°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-pentane solution at a temperature of about 30°C to about 150°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-pentane solution at a temperature of about 50°C to about 130°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-pentane solution at a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polyethylene from a polyethylene / n-pentane solution under a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0285] In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / fluid solvent solution under temperatures and pressures at which polypropylene precipitates from the solution. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / n-butane solution at temperatures between approximately 0°C and approximately 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / n-butane solution at temperatures between approximately 100°C and approximately 200°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / n-butane solution at temperatures between approximately 130°C and approximately 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / n-butane solution at pressures between approximately 0 psig (0 MPa) and approximately 2,000 psig (13.79 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / n-butane solution under a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / n-butane solution under a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0286] In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / propane solution at a temperature of about -42°C to about 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / propane solution at a temperature of about 0°C to about 150°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / propane solution at a temperature of about 50°C to about 130°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / propane solution at a pressure of about 0 psig (0 MPa) to about 6,000 psig (41.37 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / propane solution at a pressure of about 50 psig (0.34 MPa) to about 3,000 psig (20.68 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polypropylene from a polypropylene / propane solution under a pressure of approximately 75 psig (0.52 MPa) to approximately 1,000 psig (6.89 MPa).

[0287] In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / fluid solvent solution under temperatures and pressures at which polystyrene precipitates from the solution. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / n-butane solution at temperatures between approximately 0°C and approximately 220°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / n-butane solution at temperatures between approximately 100°C and approximately 200°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / n-butane solution at temperatures between approximately 130°C and approximately 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / n-butane solution at pressures between approximately 0 psig (0 MPa) and approximately 2,000 psig (13.79 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / n-butane solution under a pressure of about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating polystyrene from a polystyrene / n-butane solution under a pressure of about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

[0288] In embodiments of the present invention, a method for purifying a regenerated polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / fluid solvent solution under temperatures and pressures at which poly(dimethylsiloxane) precipitates from the solution. In embodiments of the present invention, a method for purifying a regenerated polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at temperatures between approximately 0°C and approximately 220°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at temperatures between approximately 115°C and approximately 200°C. In embodiments of the present invention, a method for purifying a regenerated polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution at temperatures between approximately 120°C and approximately 180°C. In embodiments of the present invention, a method for purifying a recycled polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 0 psig (0 MPa) to about 1,500 psig (10.34 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 50 psig (0.34 MPa) to about 1,000 psig (6.89 MPa). In embodiments of the present invention, a method for purifying a recycled polymer includes separating poly(dimethylsiloxane) from a poly(dimethylsiloxane) / n-butane solution under a pressure of about 75 psig (0.52 MPa) to about 500 psig (3.45 MPa).

[0289] In embodiments of the present invention, the polymer filtered twice is separated from the fourth solution to produce a higher purity polymer. In embodiments of the present invention, the polymer filtered twice 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) to produce a higher purity polymer.

[0290] IX. Test Method The test methods described herein are used to measure the effectiveness of various methods for purifying polymers. Specifically, the methods described demonstrate the effectiveness of a given purification method in improving color and translucency / transparency (i.e., bringing the color and opacity of recycled polymers closer to that of colorless, non-recycled polymers), reducing or eliminating elemental contamination (i.e., removal of heavy metals), reducing or eliminating non-flammable contamination (i.e., inorganic fillers), reducing or eliminating volatile compounds (in particular volatile compounds that contribute to the malodor of recycled polymers), and reducing or eliminating polymer contamination (i.e., polyethylene contamination in polypropylene).

[0291] Measurement of color and opacity The color and opacity / transparency of a polymer are important parameters in determining whether the polymer can achieve the desired visual aesthetics of the articles produced from it. Recycled polymers, particularly PCR polymers, are typically dark and opaque due to residual pigments, fillers, and other contaminants. Therefore, measuring color and opacity is an important parameter for determining the effectiveness of polymer purification methods.

[0292] Before color measurement, either a polymer powder or pellet sample was compressed into a mold to form a square test specimen measuring 30 mm wide x 30 mm long x 1 mm thick (with rounded corners). The powder sample was first cold-compressed into a sheet between stainless steel platens using clean, unused aluminum foil as a contact release layer, thereby increasing its density at room temperature (approximately 20-23°C). Next, approximately 0.85 g of the cold-compressed powder or pellet was compressed onto the test specimen using a Carver Press Model C (Carver, Inc., Wabash, IN 46992-0554 USA) preheated to 200°C, using an aluminum platen, an unused aluminum foil release layer, and a stainless steel shim with a cavity corresponding to the square test specimen of the aforementioned dimensions. The sample was heated for 5 minutes before pressure was applied. After 5 minutes, it was compressed in the press with a water pressure of at least 2 tons (1.81 metric tons) for at least 5 seconds, and then released. Next, the molded laminate was removed and cooled between two thick, flat metal heat sinks. Then the aluminum foil release layer was peeled off the sample and discarded. The casting burr around at least one side of the sample was removed down to the edge of the mold, and then the sample was extruded from the mold. Each test specimen was visually evaluated for defects such as voids / bubbles, and only specimens without defects in the color measurement area (minimum diameter 0.7 inches (17.78 mm)) were used for color measurement.

[0293] The color of each sample is determined by the International Commission on Illumination (CIE). * a * , b * It was characterized using the 3D color space L. * Dimension is a measure of the lightness of the sample, L * =0 corresponds to the darkest black sample, L * =100 corresponds to the brightest white sample. Dimension a * This is a scale of red or green in the sample, and a * When the value is positive, it corresponds to red, and a * When the value is negative, it corresponds to green. Dimension b * b is the blue or yellow measurement of the sample.* When the value is positive, it corresponds to yellow, and b * When the value is negative, it corresponds to blue. Each L of the test sample is a square with dimensions of 30mm width x 30mm length x 1mm thickness. * a * b * The values ​​were measured using a Hunter Lab model LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-5280, USA). The spectrophotometer was configured with a D65 standard light source, an observation angle of 10°, a field of view diameter of 1.75 inches (44.45 mm), and a port diameter of 0.7 inches (17.78 mm).

[0294] The opacity of each sample is a measure of how much light passes through the sample (i.e., a measure of the sample's light transmittance), and this was determined using the contrast ratio opacity mode of the Hunter Lab spectrophotometer mentioned above. Two measurements were performed to determine the opacity of each sample. One was the lightness value Y of the sample backed with a white backing material. White Backing This is for measuring the lightness value Y of a sample backed with a black backing material. Black Backing This was for measuring [the value]. Next, the opacity was calculated from the lightness value using the following formula.

[0295]

number

[0296] elemental analysis Many recycled polymers contain unacceptably high levels of heavy metal contamination. The presence of heavy metals, such as lead, mercury, cadmium, and chromium, can prevent the use of recycled polymers in certain applications, including food or pharmaceutical contact applications, or medical device applications. Therefore, measuring heavy metal concentrations is crucial when determining the effectiveness of polymer purification methods.

[0297] Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Test solutions were prepared in n=2 to n=6 groups, depending on sample availability, by scooping approximately 0.25 g of sample with 4 mL of concentrated nitric acid and 1 mL of concentrated hydrofluoric acid (HF). The samples were decomposed using an Ultrawave microwave sample decomposition protocol consisting of raising the temperature to 125°C over 20 minutes, raising it to 250°C over 10 minutes, and maintaining the temperature at 250°C for 20 minutes. The decomposed samples were allowed to cool to room temperature. To this decomposed sample, 0.25 mL of 100 ppm Ge and Rh were added as internal standards, and the sample was then diluted to 50 mL. To evaluate the accuracy of the measurements, pre-decomposition spikes were prepared by spiking non-recycled polymers. Non-recycled polymer spike samples were weighed using the same procedure as described above and spiked with appropriate amounts of each single-element standard of interest (including Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb). Spikes were prepared at two different levels: "low-concentration spikes" and "high-concentration spikes." Each spike was prepared in triple replication. In addition to spiking the non-recycled polymer, blanks were also spiked to ensure no errors occurred during pipetting and to track recovery throughout the process. Samples spiked from the blanks were also prepared in triple replication at two different concentrations and processed in the same manner as the spiked non-recycled polymer and test samples. Solutions containing Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb were prepared at 0.05, 0.1, 0.5, 1, 5, 10, 50, 100, and 500 ppb to create a nine-point calibration curve. All calibration standards were prepared by diluting undiluted standard reference solutions with internal standards consisting of 100 ppm Ge and Rh in 0.25 mL, 4 mL of concentrated nitric acid, and 1 mL of concentrated HF. The prepared standard solutions, test samples, and spiked test samples were analyzed using an Agilent 8800 ICP-QQQMS, optimized according to the manufacturer's recommendations.The observed m / z values ​​and collision cell gases used for analysis for each sample 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, sum of 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 the internal standard for all elements with a m / z less than 103 m / z, and Rh was used as the internal standard for all elements with a m / z greater than 103 m / z.

[0298] residual ash Many recycled polymers contain various fillers, such as calcium carbonate, talcam, and glass fibers. These fillers alter the physical properties of the polymer in ways that are useful for the original application but may be unnecessary for subsequent applications. Therefore, measuring the amount of fillers is important when determining the effectiveness of the polymer purification method.

[0299] Thermogravimetric analysis (TGA) was performed to determine the amount of non-combustible material (sometimes called ash) in the sample. Approximately 5–15 mg of the sample was placed in a platinum sample dish and heated to 700°C at a rate of 20°C / min in an air atmosphere using a TA Instruments Model Q500 TGA instrument. The sample was held isothermally at 700°C for 10 minutes. After isothermal holding, the residual mass percentage was measured at 700°C.

[0300] Odor analysis Odor sensory analysis was performed by placing approximately 3g of each sample into a 20mL glass vial and allowing the samples to equilibrate at room temperature for at least 30 minutes. After equilibration, each vial was opened, and a trained evaluator smelled the headspace (bunny sniff) to determine the odor intensity and descriptor profile. Odor intensity was evaluated according to the following scale: 5 = very strong, 4 = strong, 3 = moderate, 2 = weak to moderate, 1 = weak, 0 = no odor.

[0301] Polymer contamination analysis Many recycled polymers, especially those derived from mixed liquid resources, may contain unwanted polymer contamination. While not bound by any particular theory, polymer contamination, such as polyethylene contamination in polypropylene, can affect the physical properties of the polymer by creating heterogeneous phases and resulting in weaker interfaces. Furthermore, polymer contamination can also increase the opacity of the polymer and affect its color. Therefore, measuring the amount of polymer contamination is important when determining the effectiveness of polymer purification methods.

[0302] Quasicrystalline polymer contamination was evaluated using differential scanning calorimetry (DSC). For example, to measure the amount of polyethylene contamination in polypropylene, five sets of polypropylene / polyethylene blends were prepared, each containing 2, 4, 6, 8, and 10 wt% Formolene® HB5502F HDPE (Formosa Plastics Corporation, USA) in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, BV). Approximately 5–15 mg of each sample was sealed in an aluminum DSC dish and analyzed using a TA Instruments Model Q2000 DSC using the following method: 1. Equilibrium is reached at 30.00°C. 2. Increase the temperature to 200.00°C at a rate of 20.00°C / min. 3. Mark the end point of cycle 0. 4. Increase the temperature to 30.00°C at a rate of 20.00°C / min. 5. Mark the end point of Cycle 1. 6. Increase the temperature to 200.00°C at a rate of 20.00°C / min. 7. Mark the end point of Cycle 2. 8. Increase the temperature to 30.00°C at a rate of 20.00°C / min. 9. Mark the end point of Cycle 3. 10. Increase the temperature to 200.00°C at a rate of 5.00°C / min. 11. Mark the end point of Cycle 4.

[0303] Using a DSC thermogram at 5.00°C / min, the enthalpy of melting of the HDPE peak at approximately 128°C was calculated for each sample with known HDPE content. By plotting the enthalpy of melting against known HDPE wt% concentrations, a linear calibration curve was obtained, as shown in Figure 2.

[0304] Samples with unknown PE content were analyzed using the same DSC instrument and method described above. The PE content was calculated using the calibration curve described above. The specific HDPE used to generate the calibration curve is very likely to have a different degree of crystallinity than the polyethylene (or polyethylene blend) contamination that may be present in the recycled polymer sample. Crystallinity can independently affect the enthalpy of fusion of the measured polyethylene and, therefore, can also affect the calculation of the resulting polyethylene content. However, the DSC test described herein is intended to be used as a relative indicator for comparing the effectiveness of various methods for purifying polymers and is not intended for the strict quantification of polyethylene content in polymer blends. Although the method described above describes the measurement of polyethylene contamination in polypropylene, this method can also be applied to the measurement of other quasicrystalline polymers using different temperature ranges and peaks in the DSC thermogram. Furthermore, other methods such as nuclear magnetic resonance (NMR) spectroscopy can also be used to measure the amount of contamination of both quasicrystalline and amorphous polymers in the sample.

[0305] Analysis and measurement of chemical pollutants For pesticides, the EN 15662:2018-07 Modular QuEChERS method was applied. For alkylphenol ethoxylates, alkylphenols, and bisphenols, the following techniques were applied: the sample was cut, homogenized, and weighed. Then, an internal standard (deuterated bisphenol A) was added, followed by extraction of the sample with hexane at room temperature, derivatization with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide), and the contaminant level was determined by GC-MSD. For dioxins, furans, and PCBs, the ISO / IEC 17025:2005 method was applied. The sample was cut into small pieces, an aliquot of the sample material was added to the 13C / 12C labeled PCDD / F internal standard, matrix extraction and disruption with hexane and H2SO4 was performed for 1 hour, re-extraction with hexane (3 times for 30 minutes), multi-step chromatography cleanup was performed, the 13C / 12C labeled PCDD / F recovery standard was added to the measurement solution, and quantification was performed using the internally labeled PCDD / F standard (isotope dilution technique and internal standard technique). For organotin compounds, the method followed the EDANA protocol (WSP 351) for organotin compounds in absorbent sanitary products and their constituent materials. More specifically, the sample was extracted with an ethanol solution of sodium diethyldithiocarbamate, alkylated with sodium tetraethylborate, and transferred to the organic phase by extraction with hexane. Next, tetrasubstituted organotin compounds were separated using capillary gas chromatography and verified using an AED or MS as the 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 and extraction with hexane at room temperature were used. The extracted phthalates were then identified and quantified by GC-MSD. For PAHs, the sample was cut, homogenized, and weighed. Then, an internal standard for deuterated PAHs was added, and the sample was extracted with hexane. The extracted PAHs were further purified with silica gel, concentrated, and then characterized by GC-MSD.

[0306] Amount of loosely bound surface contamination The amount of loosely bound surface contamination was measured by the following method: Approximately 20 g of plastic was added to a 1,000 mL round-bottom flask. Approximately 300 mL of distilled water was added to the 1,000 mL round-bottom flask. The round-bottom flask was capped and then shaken vigorously for approximately 60 seconds. The water was decanted from the flask. Approximately 600 mL of additional distilled water was added to the 1,000 mL flask and immediately decanted, leaving the original recycled polymer containing a small amount of water. The recycled polymer was removed from the round-bottom flask and dried overnight in a convection oven at 60°C. The percentage change in the mass of the plastic represents the amount of loosely bound surface contamination.

[0307] Color measurement for ΔE calculation Color measurements were performed using a Minolta Spectrophotometer, Model CM580d. The "white" portion of the Leneta card was used as the common background and as the reference point for ΔE calculation. ΔE is the color difference between the sample color and the reference color. Color measurements were performed using a D65 light source and a 10° observer. Each compressed thermoplastic starch composition sample was measured at least three times. The L, a, and b values ​​were averaged and reported along with the ΔE value. The ΔE value for a pure white Leneta card is 0, and a positive deviation from 0 indicates an increase in discoloration. Those skilled in the art will know how to calculate the ΔE value.

[0308] X. Example Comparative Example 1 - Purification of highly controlled post-commercial film using a commercially available water washing process #1, followed by melt densification. Recycled polymers consisting of high-control post-market film #1 were fed into a commercial refining process. The washing process consisted of shredding, various water washing steps, drying, and melt densification. Shredding homogenized the material and reduced its basic size. Water washing should effectively remove surface contamination. However, the ability of this process to remove bulk permeable contamination should be minimal due to the low solubility of chemical contaminants in water. Small amounts of volatile bulk contamination should be removed during drying and melt densification, but overall, bulk contamination should be minimally affected. Furthermore, the high-control post-market film source used as the recycled polymer had limited chemical contamination, as indicated by low levels of pesticides, dioxins, and phthalates. Using the method disclosed in Section IX, the recycled polymers and higher-purity plastics were analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany). As shown in Table 3, after purification, higher-purity plastics contained slightly reduced levels of chemical contamination. The removal efficiency of the five selected contaminants was as follows: 4-tert-pentylphenol had a removal efficiency of 0%; bisphenol A had a removal efficiency of 94%; OCDD had a removal efficiency of 78%; PCB118 had a removal efficiency of 68%; and di-2-ethylhexyl phthalate had a removal efficiency of 22%. The average removal efficiency of the five selected contaminants was approximately 52%.

[0309] [Table 11]

[0310] Comparative Example 2 - Purification of High-Control Post-Commercial Film #2 Using Commercial Water Washing Process #2 and Subsequent Melt Densification Recycled polymers consisting of highly controlled post-market film #2 were fed into a commercially available refining process to produce higher-purity plastics. The washing process consisted of shredding, hot water washing, drying, and melt densification. As with water washing process #1, this process should remove surface contamination, but it has limitations in its ability to remove bulk permeable contamination. As shown in Table 4, the recycled polymers and higher-purity plastics were analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX. Recycled polymers from the highly controlled film source had limited chemical contamination, as indicated by low levels of dioxins, PCBs, phthalates, and PAHs. The higher-purity plastics contained a mixture of increased and slightly decreased levels of chemical contamination. The increase in certain chemical contaminants was likely due to cross-contamination from other more highly contaminated feedstreams and / or variability in the contamination levels of the feedstreams. The removal efficiency of the five selected species was as follows: 4-tert-pentylphenol had a removal efficiency of 0%. Bisphenol A had a removal efficiency of 96%. OCDD had a removal efficiency of 0%. PCB118 had a removal efficiency of 68%. Di-2-ethylhexyl phthalate had a removal efficiency of 0%. The average removal efficiency of the five selected contaminants was approximately 14%.

[0311] [Table 12]

[0312] Comparative Example 3A - Purification of post-commercial film #1 using a commercially available deinking process from Cadel. Recycled polymers consisting of commercially available post-film #1 were fed into a commercially available purification process from Cadel (http: / / cadeldeinking.com / en / ) called deinking to produce higher-purity plastics. This process consisted of shredding, aqueous deinking, washing / rinsing, and drying. From the patented technology, the deinking process involves high temperature, high pH, ​​and surfactants. Various washing steps should effectively remove surface contamination. Furthermore, small amounts of bulk permeable contamination are removed by the high temperature which increases diffusivity and the potential increase in the solubility of contaminants in water due to the surfactant / pH combination. However, low bulk extraction was expected. The incoming recycled polymer was determined to have 0.125 wt% loosely bound surface contamination compared to approximately 0.02 wt% of the higher-purity plastic in the shredded form. Therefore, this washing process removed more than 80% of the incoming loosely bound surface contamination. After washing the recycled polymer, and before analyzing for chemical contamination, the fragments were melted and densified using a single-screw extruder at 190°C to produce pellets. The pellets were ground to an average diameter of 300–500 μm. As shown in Table 5, the recycled polymer and higher-purity plastics were analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the method disclosed in Section IX. The recycled polymer contained moderate levels of chemical contamination, indicating a post-market film lacking a highly controlled lifecycle. For example, incoming dioxins such as OCDD were 40 times the LOQ, which is higher than the aforementioned highly controlled sources in Comparative Examples 1, 2, and 5. Furthermore, this particular source has a high level of paper contamination, which could lead to further chemical contamination when remelted for densification / pelletization. This particular source had a particularly high level of alkylphenols (approximately 1,000 times the LOQ), further indicating a level of chemical contamination within this recycled source. The recycled polymer consisted of shredded film, most of which was fused together with the plastic mass.Therefore, the effectiveness of surface cleaning techniques using this source is somewhat hindered because it is not possible to access completely contaminated surfaces. After the deinking process, higher-purity plastics contained reduced levels of chemical contamination. The removal efficiency of the five selected contaminants was as follows: 4-tert-pentylphenol had a removal efficiency of 71%; bisphenol A had a removal efficiency of 0%; OCDD had a removal efficiency of 60%; PCB118 had a removal efficiency of 0%; and di-2-ethylhexyl phthalate had a removal efficiency of 22%. The average removal efficiency of the five selected contaminants was approximately 31%.

[0313] Comparative Example 3B - Purification of home-use film #1 using a commercially available deinking process from Cadel. A recycled polymer consisting of used household film #1 was fed into the surface purification process of Comparative Example 3A to produce a higher purity plastic. The incoming recycled polymer was determined to have 0.047% by weight of loosely bound surface contamination, compared to approximately 0.003% by weight of the higher purity plastic. Therefore, this washing process removed more than 80% of the incoming loosely bound surface contamination. Before analyzing the chemical contamination, the fine fragments of used household film #1 were melted, densified, and pelletized using an extruder. The pelletized material was pulverized to an average particle size of 300-500 μm. As shown in Table 5, the recycled polymer and the higher purity plastic were analyzed for the class of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the method disclosed in Section IX. The recycled polymer contained extremely high levels of chemical contamination, including considerable fouling. For example, the pesticide piperonyl butoxide had approximately 7 × LOQ, alkylphenol ethoxylate had approximately 1,000 × LOQ, and dioxins and phthalates had approximately 300 × LOQ. Higher purity plastics contained reduced levels of chemical contamination. Note: Despite using the same washing process, the difference in removal efficiency between Comparative Examples 3A and 3B was considered likely to be due to 1) differences in the surface area exposed for the washing process, 2) differences in the distribution of chemical contaminants on the surface and in the bulk, and 3) inherent variability in chemical contaminants within the samples and variability in measurement techniques. The removal efficiency of the five selected species was as follows: 4-tert-pentylphenol had a removal efficiency of 38%. Bisphenol A had a removal efficiency of 92%. OCDD had a removal efficiency of 21%. PCB118 had a removal efficiency of 0%. Di-2-ethylhexyl phthalate had a removal efficiency of 73%. The average removal efficiency of the five selected contaminants was approximately 45%.

[0314] [Table 13]

[0315] Comparative Example 4 - Purification of High-Control Post-Commercial Film #3 using a Commercial Deodorization Process Recycled polymers consisting of high-control post-market film #3 were fed into a purification process described as a deodorization technique. This process consisted of exposing the pelletized feed material to a moderate temperature and continuously flushing it with air. Thus, this cleaning technique primarily removes volatile surface and bulk contaminants. However, most chemical contaminants associated with controlled end markets are highly non-volatile. As shown in Table 6, recycled polymers and higher-purity plastics were analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX. High-control film source #3 had limited chemical contamination, as indicated by low levels of dioxins, PCBs, phthalates, and PAHs. Higher-purity plastics contained slightly reduced levels of chemical contamination. The removal of the five selected species was as follows: 4-tert-pentylphenol had a removal efficiency of 88%. Bisphenol A had a removal efficiency of 96%. The removal efficiency of OCDD was 20%. The removal efficiency of PCB118 was 0%. The removal efficiency of di-2-ethylhexyl phthalate was 0%. The average removal efficiency of the five selected contaminants was approximately 41%.

[0316] [Table 14]

[0317] In general, established methods for purifying / washing film and other plastic waste, including rinsing, deinking, and devolving, are currently insufficient to adequately remove chemical contaminants, especially from highly controlled sources. Even with highly controlled sources, chemical contamination remains present and is not completely removed, which can limit the final use for certain customers. In other words, the need for cleaning technologies that can more completely remove chemical contamination to a sufficient degree for highly contaminated sources and any market desiring higher purity recycled materials remains unmet.

[0318] Example 1 - Bulk purification using immersion leaching of used household film #1 in CSTR using ethyl acetate at boiling point and atmospheric pressure. 2,000 g of ethyl acetate was added to a 5 L stirring round-bottom flask. One mechanical stirrer, one reflux condenser, and one heating jacket were attached to the flask. The mechanical stirrer was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. Heat was applied to rapidly boil the ethyl acetate (approximately 77.1°C) in about 10 minutes. After reaching the boiling point of ethyl acetate, the heat input was reduced to achieve a consistent reflux rate of approximately 10 mL / min at the boiling point of approximately 77.1°C. Used household film #1 was added to the round-bottom flask containing the boiling ethyl acetate. Approximately 110-120 g of used household film #1 in the form of fine fragments was added. The fragments were approximately 20-30 μm thick. Therefore, the surface area to volume ratio of the recycled polymer was approximately 80 mm². -1The stirring was sufficient to completely detach the film fragments in ethyl acetate and prevent them from agglomerating. The extraction was continued for approximately 45 minutes. Stirring was stopped and the heat was removed. The ethyl acetate was decanted from the fragments. The second extraction step was completed by adding 2,000 g of preheated fresh ethyl acetate, at or near its boiling point, to the plastic fragments in a 5 L round-bottomed container. Stirring was started at 400-500 rpm, during which enough heat was added to reflux the ethyl acetate at approximately 10 mL / min. After adding the fresh ethyl acetate to the fragments, it took approximately 5 minutes to reach reflux. The second extraction was continued for a total of approximately 45 minutes. Stirring was stopped and the heat was removed. The ethyl acetate was decanted, and then the film fragments were placed in a filter flask without vacuum to further remove any remaining ethyl acetate. The film fragments were then dried overnight at room temperature. The solvent-to-regenerated polymer ratio per step was approximately 18:1 for two steps, and the total solvent-to-regenerated polymer ratio was approximately 36:1. The leaching time per stage was approximately 50 minutes for a total time of approximately 100 minutes. The dried film fragments were placed in a Pharma 11 mini twin-screw compounding machine at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm to produce the final higher-purity plastic. As shown in Table 7, the higher-purity plastic was analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the method disclosed in Section IX. The removal efficiency of the contaminant 4-tert-pentylphenol was 93%. The removal efficiency of the contaminant bisphenol A was 85%. The removal efficiency of the contaminant OCDD was 97%. The removal efficiency of PCB118 was 90%. The removal efficiency of di-2-ethylhexyl phthalate was 79%. The average removal capacity for the contaminants 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate was 89%.

[0319] [Table 15]

[0320] Example 2 - Bulk purification using immersion leaching of used household film #1 in CSTR using ethyl acetate at boiling point and atmospheric pressure. Approximately 110-120g of used household film #1 in the form of small film fragments (surface area to volume ratio approximately 80mm²) is placed in a 5L round-bottom flask. -1) was added. One mechanical stirrer, one reflux condenser, and one heating jacket were attached to the flask. Mechanical stirring was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. 2000 g of ethyl acetate was heated to boiling point in another round-bottom flask. 2000 g of boiling ethyl acetate was added to the 5 L round-bottom flask containing the film fragments. Heat was added to quickly achieve boiling conditions. Stirring at 400 rpm was sufficient to prevent the film from agglomerating and to achieve good peeling. After boiling was achieved (about 5 minutes), the heat was reduced to produce a solvent reflux rate of about 10 mL / min at about 77.1°C. Leaching was continued for a total of 20-25 minutes. After about 25 minutes, the heat was removed and the ethyl acetate was decanted from the fragments. A second 2000 g of preheated, fresh boiling ethyl acetate was added to the fragments in the 5 L round-bottom flask to complete the second leaching step. Stirring was started at 400-500 rpm, during which enough heat was applied to reflux at approximately 10 mL / min. The time to reach reflection was approximately 5 minutes. The second leaching was continued for a total of 25 minutes. The heat was removed and stirring was stopped. Ethyl acetate was decanted, and then the film fragments were added to a filter funnel on a filter flask without vacuum. After approximately 10 minutes, the fragments were placed on a baking sheet and the solvent was evaporated overnight. The total leaching solvent to recycled polymer ratio per stage was approximately 18:1 for two stages, and the total leaching solvent to recycled polymer ratio was approximately 36:1. The leaching time per stage was approximately 30 minutes for a total time of approximately 60 minutes. The dried film fragments were placed in a Pharma 11 mini twin-screw compounding machine at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm to produce the final higher purity plastic. As shown in Table 8, higher purity plastics were analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the methods disclosed in Section IX. The removal efficiency for the contaminant 4-tert-pentylphenol was 90%. The removal efficiency for the contaminant bisphenol A was 79%. The removal efficiency for the contaminant OCDD was 97%.The removal efficiency of PCB118 was 82%. The removal efficiency of di-2-ethylhexyl phthalate was 98%. The average removal capacity of the contaminants 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate was 89%.

[0321] The overall removal efficiencies of Example 1 and Example 2 are very similar, despite the shorter leaching time in Example 2, suggesting that leaching is limited by the solvent sink rather than by time. Therefore, it is likely that removal can be improved by manipulating the leaching process with fewer total times but more steps and / or a slightly higher leaching solvent to regenerated polymer mass ratio.

[0322] [Table 16]

[0323] Example 3 - Bulk purification using immersion leaching of used household film #1 in a CSTR using THF at boiling point and atmospheric pressure. 2,000 g of THF was added to a 5 L stirring round-bottom flask. One mechanical stirrer, one reflux condenser, and one heating jacket were attached to the flask. The mechanical stirrer was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. Heat was applied to rapidly boil the THF (approximately 66°C) in about 10 minutes. After reaching the boiling point of THF, the heat input was reduced to achieve a consistent reflux rate of approximately 10 mL / min at the boiling point of approximately 66°C. Used household film #1 was added to the round-bottom flask containing the boiling THF solvent. Approximately 110-120 g of used household film #1 in the form of fine fragments was added (surface area to volume ratio approximately 80 mm²). -1The stirring was sufficient to completely detach the film fragments in the THF and prevent them from agglomerating. The leaching was continued for approximately 45 minutes. The stirring was stopped and the heat was removed. The THF was decanted from the fragments. The second leaching step was completed by adding 2,000 g of preheated fresh THF at or near its boiling point to the plastic fragments in a 5 L round-bottomed container. Stirring was started at 400-500 rpm, during which enough heat was added to reflux the THF at approximately 10 mL / min. After adding the fresh THF to the fragments, it took approximately 5 minutes to reach reflux. The second leaching was continued for a total of approximately 45 minutes. The stirring was stopped and the heat was removed. The THF was decanted, and then the film fragments were placed in a filter flask without vacuum to further remove residual THF. The film fragments were then dried overnight at room temperature. The total leaching solvent to recycled polymer ratio per stage was approximately 18:1 for two stages, and the total leaching solvent to recycled polymer ratio was approximately 36:1. The leaching time per stage was approximately 50 minutes for a total time of approximately 100 minutes. The dried film fragments were placed in a Pharma 11 mini twin-screw compounding machine at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm to produce the final higher-purity plastic. As shown in Table 9, the higher-purity plastic was analyzed for classes of chemical contaminants typically present in recycled materials by GALAB Laboratories (Am Schleusengraben 7, 21029 Hamburg, Germany) using the method disclosed in Section IX. The removal efficiency of the contaminant 4-tert-pentylphenol was 98%. The removal efficiency of the contaminant bisphenol A was 91%. The removal efficiency of the contaminant OCDD was 96%. The removal efficiency of PCB118 was 67%. The removal efficiency of di-2-ethylhexyl phthalate was over 98%. The average removal capacity of the contaminants 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and di-2-ethylhexyl phthalate was 90%.

[0324] [Table 17]

[0325] Example 4 - Combination of surface cleaning by Cadel deinking in CSTR using ethyl acetate and bulk purification including immersion leaching with used household film #1 at boiling point and atmospheric pressure. A recycled polymer made from used household film #1 was purified as in Comparative Example 3B to produce a higher purity plastic #1 (surface area to volume ratio approximately 8 mm²). -1). Higher purity plastic #1 was supplied to the bulk purification step of the extraction as follows: Approximately 110-120 g of higher purity plastic from Comparative Example 3B in film fragment form was added to a 5 L round-bottom flask. One mechanical stirrer, one reflux condenser, and one heating jacket were attached to the flask. Mechanical stirring was set to 400 rpm. The heating jacket was controlled by a variable voltage transformer. 2000 g of ethyl acetate was heated to boiling point in another round-bottom flask. 2000 g of boiling ethyl acetate was added to the 5 L round-bottom flask containing the film fragments. Heat was added to quickly achieve boiling conditions. Stirring at 400 rpm was sufficient to prevent film aggregation and achieve good peeling. After boiling was achieved (approximately 5 minutes), the heat was reduced to produce a solvent reflux rate of approximately 10 mL / min at approximately 77.1°C. Leaching was continued for a total of 20-25 minutes. After approximately 25 minutes, the heat was removed, and then ethyl acetate was decanted from the fragments. A second 2000g of freshly preheated boiling ethyl acetate was added to the fragments in a 5L round-bottom flask to complete the second leaching step. Stirring was started at 400-500 rpm, while adding enough heat to achieve reflux at approximately 10 mL / min. The time to reach reflux was approximately 5 minutes. The second extraction was continued for a total of 25 minutes. The heat was removed, and stirring was stopped. Ethyl acetate was decanted, and then the film fragments were added to a filter funnel on a filter flask without vacuum. After approximately 10 minutes, the fragments were placed on a baking sheet, and the solvent was allowed to evaporate overnight. The leaching solvent to polymer ratio per step was approximately 18:1, for a time of approximately 30 minutes per step. Thus, the total leaching solvent to plastic ratio was approximately 36:1, and the total leaching time was approximately 60 minutes. Dry film fragments were fed into a Pharma 11 mini twin-screw compounding machine at approximately 190°C to produce pellets. The pellets were then mechanically ground to an average particle size of approximately 1 mm in diameter to produce the final higher-purity plastic #2. As shown in Table 10, the higher-purity plastic #2 was analyzed for the class of chemical contaminants typically present in rec...

Claims

1. A method for purifying recycled polymers, a. To obtain the recycled polymer, wherein the recycled polymer is selected from the group consisting of consumer post-use recycled (PCR) polymers, industrial post-use recycled (PIR) polymers, and combinations thereof, the recycled polymer contains contaminants, each contaminant has a concentration, and the contaminants of the recycled polymer include at least one of alkylphenols, bisphenols, dioxins, PCBs, and phthalates. b) Leaving the alkylphenol, bisphenol, dioxin, PCB, or phthalate from the regenerated polymer in a plurality of leaching steps using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure of atmospheric pressure to 1,000 atm, over a total residence time and the residence time of each leaching step, with an average removal efficiency, to produce a leached polymer containing at least one of alkylphenol, bisphenol, dioxin, PCB, or phthalate, each having a concentration greater than 55%. c. Dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa), thereby producing a first solution containing the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant. d. Precipitating the first solution at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a second solution containing the precipitated polymer, at least one dissolved contaminant, and a smaller amount of the at least one suspended contaminant. e. Filtering the second solution by mechanical filtration at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a third solution containing the filtered polymer, at least one dissolved contaminant, and a smaller amount of the at least one suspended contaminant. f. The third solution is filtered by adsorption filtration at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a fourth solution containing the polymer that has been filtered twice. g. A method comprising separating the twice filtered polymer from the fourth solution to produce a higher purity polymer, wherein the second fluid solvent has the same chemical composition as or a different chemical composition from the first fluid solvent.

2. The method according to claim 1, wherein the alkylphenol, bisphenol, dioxin, PCB, and phthalate comprises at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate.

3. The method according to claim 1, wherein the number of leaching steps is 1 to 50.

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

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

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

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

8. The method according to claim 1, wherein the regenerated polymer is surface-cleaned in a non-densified state in a surface cleaning step prior to the leaching step to produce a surface-cleaned polymer, the surface cleaning results in a reduction of more than 80% of loosely bound surface contamination, the regenerated polymer before surface cleaning has an average surface area to volume ratio of more than 1 mm⁻¹, the surface cleaning process is a deinking type surface cleaning process, the deinking process results in a ΔE change of less than 10% between the deinked polymer and the regenerated polymer that does not contain surface-printed ink, the leaching step is carried out in a continuous stirred tank reactor (CSTR), the leaching solvent is ethyl acetate, the CSTR comprises three leaching steps, the leaching temperature is 77°C, the leaching pressure is near atmospheric pressure, the residence time for each of the leaching steps is 20 minutes, the average removal efficiency is more than 55%, and the leached polymer is deflated and densified using melt extrusion to produce leached polymer pellets.

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

10. The method according to claim 1, wherein the leached polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percentage concentration of at least 0.5%.

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

12. The method according to claim 1, wherein the fluid solvent has standard boiling points below 0°C and above -45°C, and a standard enthalpy change of evaporation of less than +25 kJ / mol.

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

14. The method according to claim 1, wherein the temperature in the dissolution step, the precipitation step, and the filtration step is 110°C to 220°C, and the pressure in the dissolution step, the precipitation step, and the filtration step is 400 psig (2.76 MPa) to 2,600 (17.93 MPa).

15. A method for purifying recycled polymers, a. To obtain the recycled polymer, wherein the recycled polymer is selected from the group consisting of consumer post-use recycled (PCR) polymers, industrial post-use recycled (PIR) polymers, and combinations thereof, the recycled polymer contains contaminants, each contaminant has a concentration, and the contaminants of the recycled polymer include at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate. b. The recycled polymer is surface-cleaned in a non-densified state to produce a surface-cleaned polymer, wherein the surface cleaning results in a reduction of more than 80% of loosely bound surface contamination. c. Leaving the 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate from the regenerated polymer in a plurality of leaching steps using a leaching solvent at a temperature below the primary melting point of the regenerated polymer and a pressure of atmospheric pressure to 1,000 atm, over a total residence time and the residence time of each leaching step, with an average removal efficiency, to produce an leached polymer containing at least one of 4-tert-pentylphenol, bisphenol A, OCDD, PCB118, and 2-ethylhexyl phthalate, each having a concentration greater than 55%. d. Dissolving the leached polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa), thereby producing a first solution containing the dissolved polymer, at least one dissolved contaminant, and at least one suspended contaminant. e. Precipitating the first solution at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a second solution containing the precipitated polymer, at least one dissolved contaminant, and a smaller amount of the at least one suspended contaminant. f. The second solution is filtered by mechanical filtration at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa) to produce a third solution containing the filtered polymer, at least one dissolved contaminant, and a smaller amount of the at least one suspended contaminant. g. The third solution is brought into contact with one or more solid media at a temperature of 90°C to 280°C and a pressure of 200 psig (1.38 MPa) to 9,000 psig (62.05 MPa), and the third solution is filtered by adsorption filtration to produce a fourth solution containing a polymer that has been filtered twice. h. A method comprising separating the twice filtered polymer from the fourth solution to produce a higher purity polymer, wherein the second fluid solvent has the same chemical composition as or a different chemical composition from the first fluid solvent.

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