Process for purifying recycled polyethylene

Abstract

A process for purifying a recycled polyethylene is disclosed. The process includes dissolving recycled polyethylene in a solvent with a boiling point higher than 70°C and a relative energy difference between the solvent and the polyethylene in the recycled polyethylene, as calculated using Hansen Solubility Parameters, less than or equal to 0.8 to provide a first polyethylene-containing solution, and contacting the first polyethylene-containing solution with an adsorption media to obtain a second polyethylene-containing solution. The second polyethylene-containing solution is separated to provide a purified recycled polyethylene.

Description

[0001] PROCESS FOR PURIFYING RECYCLED POLYETHYLENE

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to a process for purifying recycled polymers, which may include post-consumer and post-industrial recycled plastics. In particular, the disclosed process is useful for the purification of recycled polyethylene.

[0004] BACKGROUND ART

[0005] Plastics have become an essential pilar of the modem global consumer economy Although recycling of plastics is highly desirable to minimize environmental impacts, it faces numerous challenges for broader deployment. For example, high levels of undesirable contaminants and marked decline in mechanical properties limit the applicability of recycled plastics. Traditional plastic recycling processes usually include collection of post-industrial or post-consumer plastics, sorting, grinding, washing, drying, extruding, and pelletizing to provide a recycled plastic. However, the previous cycle of use of the plastic feedstock and thermo-mechanical conditions of the recycling process may lead to further degradation of the polymer matrix as well as retention of existing additives and associated putative degradation products into the recycled plastic resin.

[0006] Although recyclates are routinely subjected to aqueous and / or caustic washes in conventional mechanical recycling processes, contaminants such as colorants and additives remain trapped within the polymer matrix, significantly reducing their spectrum of potential applications. As such, there is a need to develop a process capable of overcoming this mechanical recycling drawback and decontaminate recyclates to realize “virgin-like” quality recyclates.

[0007] SUMMARY OF INVENTION

[0008] In one aspect, the present disclosure provides a process for purifying recycled polyethylene, the process including dissolving at least a portion of recycled polyethylene in a solvent to provide a first polyethylene -containing solution; contacting the first polyethylene containing solution with an absorption media to obtain a second polyethylene -containing solution; and separating a purified recycled polyethylene from the second polyethylenecontaining solution, wherein the solvent has a boiling point higher than 70°C and wherein; and wherein a relative energy difference (RED) between the solvent and the polyethylene in the recycled polyethylene, calculated using Hansen Solubility Parameters, is less than or equal to 0.8. In some embodiments, the RED is less than or equal to 0.5. In some embodiments, the solvent is cyclohexane, xylenes, or a combination thereof. In some embodiments, the solvent is cyclohexane. In some embodiments, the solvent is xylenes.

[0009] In some embodiments, the dissolving step is performed at a temperature of from 90°C to 200°C.

[0010] In some embodiments, the adsorption media comprises activated alumina, silica, zeolite, aluminosilicates, clay, diatomaceous earth, or combinations thereof.

[0011] In some embodiments, the adsorption media comprises activated alumina. In some embodiments, the activated alumina has an average particle size of less than 1.4 mm.

[0012] In some embodiments, the adsorption media comprises silica. In some embodiments, the adsorption media comprises attapulgite clay. In some embodiments, the attapulgite clay has an average particle size of less than 0.6 mm.

[0013] In some embodiments, one or more of the dissolving, contacting, and separating are performed at a pressure of from 150 psi to 1600 psi. In some embodiments, one or more of the dissolving, contacting, and separating are performed at a pressure from 300 psi to 1200 psi. In some embodiments, the dissolving is at a pressure from 300 psi to 1200 psi.

[0014] In some embodiments, the separating is by liquid-liquid extraction or liquid-solid separation.

[0015] In some embodiments, the separating comprises contacting the second polyethylenecontaining solution with an anti-solvent having an RED greater than 1.1.

[0016] In some embodiments, the process of purifying recycled polyethylene disclosed herein further includes pretreating the recycled polyethylene prior to the dissolving.

[0017] In some embodiments, the pretreating comprises contacting the recycled polyethylene with a supercritical fluid. In some embodiments, the supercritical fluid comprises dimethyl ether or carbon dioxide. In some embodiments, the supercritical fluid is carbon dioxide. In some embodiments, the supercritical fluid further comprises ethanol. In some embodiments, the supercritical fluid further comprises cyclohexane.

[0018] In some embodiments, the pretreating comprises soaking and / or swelling the recycled polyethylene in a pretreatment solvent. In some embodiments, the pretreatment solvent comprises a cycloalkane with a boiling point of 45 to 120°C, an aliphatic alkane with a boiling point of 35 to 100°C, an isoparaffin with a boiling point of 25 to 100°C. In some embodiments, the pretreating further comprises removing the pretreatment solvent after the soaking and / or swelling to provide a soaked recycled polyethylene, and further purifying the soaked recycled polyethylene through solid-liquid extraction, liquid-liquid extraction, filtration, or a combination thereof.

[0019] In some embodiments, the process of purifying recycled polyethylene further comprises filtering the first polyethylene-containing solution prior to the contacting step.

[0020] In some embodiments, the first polyethylene-containing solution comprises up to 40 wt.% dissolved polyethylene.

[0021] The present disclosure also provides a purified recycled polyethylene, purified according to the processes disclosed herein.

[0022] In some embodiments, the purified recycled polyethylene has a lightness improvement, AZ,*, of at least 5% over the recycled polyethylene. In some embodiments, the lightness (L*) improvement is at least 30%.

[0023] In some embodiments, the purified recycled polyethylene has an opacity improvement, AO, of at least 15% over the recycled polyethylene. In some embodiments, the opacity improvement is at least 40%.

[0024] In some embodiments, the purified recycled polyethylene has a colour improvement, AE, of at least 30.

[0025] In some embodiments, the purified recycled includes less than 1.5 wt.% ash; less than 240 ppm of antioxidants; and less than 50 ppm of slip agents cis- 13-docosenamide, (Z)-docos- 13-enamide, and N,N'-(ethane-l,2-diyl)di(octadecanamide).

[0026] Other aspects of the invention are discussed throughout this specification. Any aspects discussed with respect to one aspect of the invention applies to other aspects of the invention as well and vice versa. Each aspect described herein is understood to be aspects of the invention that are applicable to other aspects of the invention. It is contemplated that any aspect discussed herein can be combined with other aspects discussed herein and / or implemented with respect to any process or composition of the invention, and vice versa. Furthermore, compositions of the invention can be used to achieve processes of the invention.

[0027] Other objects, features and advantages of the present disclosure will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

[0028] BRIEF DESCRIPTION OF DRAWINGS

[0029] Advantages of the process disclosed herein may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale.

[0030] Figure 1 is a block flow diagram showing the major steps of the process of the present disclosure.

[0031] Figure 2 shows photographs exemplifying the recorded appearance improvement of the purified rPE of Experiment 15 (right) by comparing to parent rPE (left) containing 40 wt. % colored flexibles and 60 wt.% clear rPE flexible.

[0032] Figure 3 shows photographs exemplifying the recorded appearance improvement of the purified rPE of Experiment 20 (right) when compared to parent commercial mechanically recycled colored rPE pellets (left).

[0033] Figure 4 shows photographs exemplifying the recorded appearance improvement of the purified rHDPE of Experiment 24 (right) when compared to post-consumer colored rHDPE granules (left).

[0034] DESCRIPTION OF EMBODIMENTS

[0035] A discovery has been made that provides a solution to at least one or more of the problems associated with purifying recycled polyethylene resins. In one non-limiting aspect, solutions are found by purifying recycled polyethylene in a process that includes dissolving at least a portion of recycled polyethylene in a solvent to provide a first polyethylene - containing solution; contacting the first polyethylene -containing solution with an absorption media to obtain a second polyethylene -containing solution; and separating a purified recycled polyethylene from the second polyethylene-containing solution, wherein the solvent has a boiling point higher than 70°C and wherein the relative energy difference (RED) between the solvent and the polyethylene in the recycled polyethylene, calculated using Hansen Solubility Parameters, is < 0.8. In one non-limiting aspect, the purified recycled polyethylene provided by the process provides a solution to one or more problems associated with use of recycled plastic polymers, such as recycled polyethylene. Some non-limiting solutions are shown in the Examples of this specification. These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

[0036] Definitions

[0037] The following includes definitions of various terms and phrases used throughout this specification.

[0038] “Virgin polyethylene” refers to manufactured polyethylene that has not been converted to a finished product. Virgin polyethylene is not recycled polyethylene and, thus, the term “virgin” is used herein to distinguish between the two.

[0039] “Recycled polyethylene” refers to polyethylene that has been obtained from, made from, and / or recovered from a polyethylene-containing waste or recycling stream. Unless mentioned otherwise, the recycled polyethylene can be post-consumer or post-industrial recycled polyethylene and / or contaminated recycled polyethylene. Post-consumer recycled (PCR) polyethylene refers to polyethylene from a waste or recycling stream generated by a consumer after a polyethylene -containing article has been used for an original or previous purpose and disposed into the waste or recycling stream. Post-industrial recycled (PIR) polyethylene refers to polyethylene from a waste or recycling stream generated during a production process (such as for example, the manufacture of a polyethylene -containing product) or excess polyethylene-containing material used in a production process (such as, for example, excess product packaging), or material diverted to the waste stream after a manufacturing process but before consumer use. It is to be understood that recycled polyethylene may contain non-polyethylene and non-polymeric components and / or contaminants. Non-limiting examples of such components and / or contaminants that can be present in recycled polyethylene include compatibilizers, pigments, and / or additives. Recycled polyethylene has been exposed to at least one heat history. It will be appreciated by those skilled in the art that “heat history” refers to the melting of polyethylene, for example to form a finished good.

[0040] “Purified recycled polyethylene” refers to a polyethylene having fewer contaminants relative to the same recycled polyethylene prior to a purification step, such as the purification process disclosed herein.

[0041] “Soaked recycled polyethylene” refers to a polyethylene that has increased in volume and / or mass due to contact with a liquid.

[0042] “Hansen Solubility Parameters (HSP)” refers to a solubility parameter based on polymer-solvent interaction provided in Hansen, C. M., Hansen Solubility Parameters: A User ’s Handbook, Second Edition, 2nd ed.; CRC Press, Boca Raton (2007), DOI: 10. 1201 / 9781420006834; Hansen, C. M., Polymer Degradation and Stability, 77 (2002) 43- 53, DOI: 10.1016 / S0141-3910(02)00078-2; and Zhao, Y. B. et al., Chemosphere 209 (2018) 707-720, DOI: 10.1016 / j.chemosphere.2018.06.095.

[0043] The Hansen Solubility Parameters for each solvent may be used to calculate the solubility parameter “distance” (Ra) between any two materials. The principle of Hansen solubility parameters is based on the total energy of vaporization expressed as three distinct types of interactions: 3D (energy density arising from intermolecular dispersion forces), 8p (energy arising from dipolar intermolecular forces), and 5H (energy arising from intermolecular hydrogen bonding forces). As such, the relative affinity of selected solvents for a material (for example, polymers such as polyethylene) can be efficiently assessed by calculating the Hansen Solubility Parameter “distance” (Ra), defined by the distance between the selected solvent and polymers calculated from their respective solubility parameter components as follow:

[0044] Ra2= 4(<5B2— <5B1)2+ (SP2— 8p )2+ (<5H2— <5H1)2

[0045] Hansen’s model uses spheres to show the solubility range of polymers in a three- dimensional space. The radius of the sphere of a polymer is referred to as the radius of interaction (Ro). The ratio Ra / Ro is referred to as the “Relative Energy Difference” (RED) and is indicative of where a given solute (for example, a polymer) falls within the solubility sphere of the solvent. Generally, and as the skilled person will appreciate, if the solvent is located within the sphere (that is, Ra < Ro), it is expected to have sufficient affinity for the polymers to result in dissolution of the polymer.1

[0046] “HDPE” refers to high density polyethylene, which generally has a density of greater or equal to 0.941 g / cm3, or for example, from 0.941 to 0.97 g / cm3. HDPE has a low degree of branching. HDPE may be produced using chromium / silica catalysts, Ziegler-Natta catalysts, or metallocene catalysts. HDPE, and the other polyethylenes described herein, typically contain additives.

[0047] “LDPE” refers to low density polyethylene, which is a polyethylene with a high degree of branching with long chains. Often, the density of a LDPE will range from 0.910 g / cm3to 0.940 g / cm3. LDPE may be created by free radical polymerization under conditions of high ethylene pressure.

[0048] “LLDPE” refers to linear low density polyethylene, which is a polyethylene with significant numbers of short branches resulting from copolymerization of ethylene with at least one C3-C12 a-olefin comonomer, e.g., butene, hexene or octene. Typically, LLDPE has a density in the range of 0.915 g / cm3to 0.925 g / cm3. In some embodiments, the LLDPE is an ethylene hexene copolymer, or an ethylene octene copolymer, or an ethylene butene copolymer. The amount of comonomer incorporated can be from 0.5 to 12 mole %, or in some embodiments from 1.5 to 10 mole %, and in other embodiments from 2 to 8 mole % relative to ethylene. LLDPE may be produced using a wide variety of catalysts, including Ziegler Natta catalysts and single site / metallocene catalysts, and in a wide variety of processes, including gas phase, slurry, and solution processes. LLDPE is distinct from LDPE.

[0049] “MDPE” refers to medium density polyethylene, which is a polyethylene with some branching and a density in the range of 0.926 g / cm3to 0.940 g / cm3. MDPE may be produced using chromium / silica catalysts, Ziegler-Natta catalysts, or single site / metallocene catalysts and in a wide variety of processes, including gas phase, slurry, and solution processes.

[0050] “VLDPE” refers to very low density polyethylene, which is a polyethylene with high levels of short chain branching with a typical density in the range of 0.88 g / cm3to 0.915 g / cm3. In some embodiments, VLDPE is a substantially linear polymer. VLDPE is typically produced by copolymerization of ethylene with short-chain alpha-olefins (for example, 1- butene, 1-hexene, or 1-octene). VLDPE is most commonly produced using metallocene catalysts in a solution process.

[0051] The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0052] The terms “wt.%”, “% by weight”, “vol.%”, “% by volume”, “mol.%”, or “% by mol.” refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt.% of component.

[0053] The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and / or the specification includes any measurable decrease or complete inhibition to achieve a desired result.

[0054] The term “effective”, as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result.

[0055] The use of the words “a” or “an” when used in conjunction with any of the terms “comprising”, “including”, “containing”, or “having” in the claims, or the specification, may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one”. The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0056] Process for Purifying Recycled Polyethylene

[0057] It has been found that certain solvents, when used in a relatively simple process can be used to purify recycled polymers, especially recycled polyethylene. Provided herein is a process for purifying recycled polyethylene, the process including dissolving at least a portion of recycled polyethylene in a solvent to provide a first polyethylene -containing solution; contacting the first polyethylene-containing solution with an absorption media to obtain a second polyethylene-containing solution; and separating a purified recycled polyethylene from the second polyethylene-containing solution, wherein the solvent has a boiling point higher than 70°C and wherein; and wherein the relative energy difference (RED) between the solvent and the polyethylene in the recycled polyethylene, calculated using Hansen Solubility Parameters, is less than or equal to (<) 0.8.

[0058] This disclosed process for purifying contaminated recycled polyethylene, represented in 100 in Figure 1, includes dissolving the recycled polyethylene in a suitable solvent to generate a first polyethylene -containing solution at a dissolution temperature and at a dissolution pressure (102 in Figure 1); contacting the first purified polyethylene -containing solution with adsorption media for purification at a purification temperature and at a purification pressure (103 in Figure 1); and separating the purified recycled polyethylene from the solvent (105 in Figure 1). The process for purifying contaminated recycled polyethylene may optionally include a step of pretreating the contaminated recycled (101 in Figure 1). When the pretreating step is present, the recycled polyethylene provided for the dissolving step is the pretreated recycled polyethylene. The process for purifying contaminated recycled polyethylene may optionally include a step where a second solvent is added to the purified polyethylene -containing solution and a portion of the solvents removed by filtration (104 in Figure 1). When the step of a second solvent is used, the purified recycled polyethylene may be subsequently separated.

[0059] In some embodiments, the purified recycled polyethylene provided by the process disclosed herein, which may be obtained from recycled polyethylene, such as post-consumer recycled polyethylene and / or post-industrial recycled polyethylene streams, is essentially contaminant-free, pigment-free, odor-free, homogenous, and / or similar in properties to virgin polyethylene. Furthermore, in some embodiments, the physical properties of the fluid solvent of the present disclosure may enable more energy efficient processes for separation of the fluid solvent from the purified polyethylene.

[0060] Depending on the recycled polyethylene source, the purification process disclosed herein may be performed as a stand-alone process or may be incorporated into a mechanical recycling process. As the skilled person understands, typical wet mechanical recycling processes include steps of bale de-wiring, bale breakup, shredding, screening, optical sorting, washing, drying, melt filtration, extrusion, devolatilization, and pelletization. As used herein the term “wet mechanical recycling process” refers to a mechanical recycling line that includes at least one washing system. In some embodiments, the purification process disclosed herein may be performed before a washing step in the mechanical recycling process. In some embodiments, the purification process disclosed herein may be performed after the washing step in the mechanical recycling process. In some embodiments, the purification process disclosed herein is performed before the drying step of a mechanical recycling process.

[0061] The Recycled Polyethylene

[0062] Recycled polyethylene can be subjected to the purification processes disclosed herein. When the purification processes disclosed herein are incorporated into a mechanical recycling process, the recycled polyethylene is the recycled polyethylene that is the feedstock for the mechanical recycling process. In some instances, the recycled polyethylene is a composition of an individual polyethylene or a mixture of polyethylene polymer such as, for example, LLDPE and HDPE.

[0063] In some embodiments, the recycled polyethylene may have been recovered or otherwise diverted from a solid waste stream. In some embodiments, the recycled polyethylene can include post-consumer polyethylene, post-industrial polyethylene, or a combination thereof. In some embodiments, the recycled polyethylene is in the form of a flexible plastic material, such as for example a plastic film. The plastic film may include or be substantially made of polyethylene (for example, an HDPE film, an LDPE film, an LLDPE film, or a film including both LDPE and LLDPE). In some embodiments, the recycled polyethylene is a rigid plastic material. As used herein, the term “rigid plastic” refers to material that is stiff and does not readily deform under conditions of use. A non-limiting example of a rigid plastic material that may be suitable for use as a recycled polyethylene in the processes disclosed herein is a milk jug. In some embodiments, the recycled polyethylene is from recycled polyethylene that are first cleaned, next melted in an extruder, and then converted, for example, into pellets, such as in a typical mechanical recycling process. This source of recycled polyethylene may be exposed to at least two heat histories: one in the original conversion process and another in the process to prepare recycled polyethylene pellets. In some embodiments, the recycled polyethylene may be provided in the form of chips, granules, flakes, pellets, powders, slurries, solutions, and the like. The recycled polyethylene may be purchased commercially and be in the form of a bales, pellets, flakes, etc.

[0064] Recycling processes where materials experience heat histories will generally cause the formation of free radicals and hydroperoxides in the polyethylene. As such, most polyethylene is sold with an antioxidant system that contains a primary antioxidant (designed to trap free radicals) and a secondary antioxidant (designed to quench hydroperoxides). Hindered phenols are commonly used as the primary antioxidant (e.g., IRGANOX® 1010 and IRGANOX 1076, sold by BASF) and hindered phosphites are commonly used as the secondary antioxidant (e.g., IRGAPHOS® 168). However, these antioxidants may be oxidized during a heat history. It is known to measure the level of consumed antioxidants (oxidized antioxidants) in a polyethylene and to use this value of an indication of degradation, or the “wear and tear” that the polyethylene has been exposed to.

[0065] In some embodiments, the recycled polyethylene may also contain various pigments, dyes, process aides, stabilizing additives, fillers, and other performance additives that were added to the polymer during polymerization or conversion of the original polymer to the final form of an article. Non-limiting examples of pigments are organic pigments, such as carbon black, diarylides, pyralozones monoazo salts, diazo condensation pigments, isoindolines, isoindolinone, quinonaphtalones, diketopyrrolo-pyrroles, and perylenes, and other pigments that may be apparent to those having ordinary skill in the art.

[0066] The Solvent

[0067] The solvent of the present disclosure has a standard boiling point greater than about 70°C. As used herein, the expression “standard boiling point” refers to the boiling temperature at standard pressure (100 kPa, 1 bar). In some embodiments, the solvent with a standard boiling point greater than about 70°C is selected from ketones, alcohols, ethers, esters, alkenes, alkanes, and mixtures thereof. Non-limiting examples of fluid solvents with standard boing points greater than about 70°C include n-amyl acetate, benzene, n-butyl acetate, t-butyl acetate, butyl benzoate, butyl diglycol acetate, butyl ethyl ether, n-butyl propionate, chloroform, cyclohexane, di -isobutyl ketone, dimethyl cyclohexane, 1,4-dioxane, ethyl benzene, iso-butyl isobutyrate, iso-pentyl acetate, iso-propyl ether, isophorone, d-limonene, methyl cyclohexane, methyl ethyl ketone (MEK), methyl iso-amyl ketone, methyl iso-butyl ketone (MIBK), methyl oleate, methyl propyl ketone, sec-butyl acetate, toluene, xylenes, and any other substances that may be apparent to those having ordinary skill in the art.

[0068] It is known in the art that the miscibility of liquid mixtures can often be predicted qualitatively based on polarity of the liquids. This is routinely accomplished by comparing the polarity of components typically represented by the dipole moment (p) and / or dielectric constant (a) of individual components. This concept is typically referred to as the “like- dissolve-like” empirical rule in terms of the polarity of the two liquids. However, this approach is vague and ill-suited for numerous applications, such as the selection of appropriate solvent for recycled polyethylene purification. Indeed, simply comparing solvents dipole moment does not provide accurate guidance in selecting solvent for polyethylene purification. As such, other approaches are needed to assist efficient solvent selection for polyethylene purification. To this end, we have found that Hansen Solubility Parameter may be used to advantageously define solvents which are suitable for the process disclosed herein. Specifically, while it would be expected that solvents with a relative energy difference (RED) < 1 would be suitable solvent for a dissolution-based polyethylene purification process, we have found that solvent with RED < 0.8 advantageously provide purified polyethylene of greater purity and / or yield, when tested under analogous conditions of the disclosed process.

[0069] As described elsewhere herein, the RED is defined as the ratio of Rato Ro; where Ro is the radius of the polymer (e.g., polyethylene) sphere, and Ra is the distance from a given solvent point to the center of the sphere. Ro values are known for most conventional polymers. For instance, Ro = 6.6 is a typical radius of interaction for polyethylene1’2. The RED value may indicate the suitability of a solvent to purify recycled polyethylene when the ensuing solution is subsequently contacted with a solid adsorption media. In embodiments of the process described herein, advantageous solvents are characterized by an RED < 0.8. In some embodiments, the solvent has an RED of less than 0.8. In some embodiments, the solvent has an RED between 0.3 and 0.8, between 0.4 and 0.8, between 0.5 and 0.8. between 0.6 and 0.8, or between 0.7 and 0.8. In some embodiments, the solvent has an RED of 0.8. In some embodiments, the solvent has an RED of 0.5. In some embodiments, the solvent is cyclohexane, xylenes, or a combination thereof. In some embodiments, the solvent is cyclohexane. In some embodiments, the solvent is xylenes. Dissolution

[0070] The process for purifying recycled polyethylene disclosed herein includes dissolving the recycled polyethylene in a solvent at a temperature and at a pressure wherein at least a portion of recycled polymer is dissolved in the solvent to generate a first polyethylenecontaining solution. In some embodiments, some components of the recycled polyethylene can remain undissolved at this stage. The first polyethylene-containing solution, therefore, may be a slurry.

[0071] In some embodiments, the dissolving step does not dissolve at least a portion of the contaminants. That is, the solvent has a higher affinity towards polyethylene than towards at least some of the other contaminants in the recycled polyethylene. As described elsewhere herein, the contaminants may include pigments, fillers, dirt, other polymers and non- intentionally added substances. In these embodiments, the first polyethylene-containing solution may be filtered prior to the subsequent step.

[0072] In some embodiments, the process for purifying recycled polyethylene includes dissolving recycled polyethylene in a solvent at a temperature between 70°C and 280°C, such as 70°C, 80°C, 90°C, 100°C, I I0°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, or 280°C, to provide the first polyethylene-containing solution. In some embodiments, the dissolving is at a temperature between 90°C and 200°C, such as between 100°C and 160°C, between 100°C and 150°C, between 100°C and 140°C, between 100°C and 200°C, between 110°C and 200°C, between 120°C and 200°C, between 120°C and 170°C, or between 110°C and 180°C to provide the first polyethylene -containing solution. In some embodiments, the dissolving is at a temperature from 100°C to 160°C to provide the first polyethylene -containing solution.

[0073] In some embodiments, the dissolving is at a pressure from 150 psi to 1600 psi to provide the first polyethylene -containing solution, such as 150 psi, 200 psi, 300 psi, 400 psi, 500 psi, 600 psi, 700 psi, 800 psi, 900 psi, 1000 psi, 1100 psi, 1200 psi, 1300 psi, 1400 psi, 1500 psi, or 1600 psi. In some embodiments, the dissolving is at a pressure from 200 psi to 1200 psi, such as 200 psi to 1000 psi, 200 psi to 800 psi, 200 psi to 500 psi, 300 psi to 1200 psi, or 500 psi to 1200 psi, to provide the first polyethylene-containing solution.

[0074] In some embodiments, the process for purifying recycled polyethylene to provide a first polyethylene -containing solution includes dissolving recycled polyethylene in one or more of the following solvents: benzene, butyl ethyl ether, n-butyl acetate, t-butyl acetate, butyl benzoate, butyl diglycol acetate, n-butyl propionate, chloroform, cyclohexane, cyclohexanone, di-isobutyl ketone, dimethyl cyclohexane, ethyl acetate, ethyl benzene, iso- butyl isobutyrate, iso-pentyl acetate, isophorone, d-limonene, methyl cyclohexane, methyl iso-amyl ketone, methyl iso-butyl ketone (MIBK), methyl oleate, methyl propyl ketone, n- propyl acetate, n-propyl propanoate, sec-butyl acetate, toluene, xylenes. In some embodiments, the process for purifying recycled polyethylene to generate a first polyethylene -containing solution includes dissolving recycled polyethylene in one or both of cyclohexane and xylenes. In some embodiments, the process for purifying recycled polyethylene to generate a first polyethylene-containing solution includes dissolving recycled polyethylene in cyclohexane. In some embodiments, the process for purifying recycled polyethylene to generate a first polyethylene-containing solution includes dissolving recycled polyethylene in xylenes.

[0075] In some embodiments, the process for purifying recycled polyethylene includes dissolving recycled polyethylene in cyclohexane at a temperature between 100°C and 220°C, such as 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, or 220°C, to provide the first poly ethylene -containing solution. In some embodiments, the process for purifying recycled polyethylene includes dissolving recycled polyethylene in cyclohexane at a temperature between 130°C and 180°C, such as between 130°C and 170°C, between 130°C and 160°C, between 130°C and 150°C, or between 130°C and 140°C, to provide the first polyethylene -containing solution. In some embodiments, the process for purifying recycled polyethylene includes dissolving recycled polyethylene in cyclohexane at a pressure from about 1000 psi to about 1200 psi, such as 1050 psi, 1100 psi, 1150 psi, or 1200 psi, to generate the first polyethylene -containing solution. In some embodiments, a process for purifying recycled polyethylene includes dissolving recycled polyethylene in cyclohexane at a pressure from about 1000 psi to about 1600 psi, such as 1000 psi, 1100 psi, 1200 psi, 1300 psi, 1400 psi, 1500 psi, or 1600 psi, to provide the first polyethylene-containing solution. In some embodiments, the process for purifying recycled polyethylene includes dissolving recycled polyethylene in cyclohexane at a pressure from about 1200 psi to about 1400 psi to provide the first polyethylene-containing solution.

[0076] In some embodiments, the first polyethylene-containing solution includes up to 40 weight % of dissolved polyethylene. In some embodiments, first polyethylene -containing solution may contain at least any one of, at most any one of, equal to any one of, or between any two of 0.5 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.%, 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.%, 30 wt.%, 31 wt.%, 32 wt.%, 33 wt.%, 34 wt.%, 35 wt.%, 36 wt.%, 37 wt.%, 38 wt.%, 39 wt.% and 40 wt.% of dissolved polyethylene.

[0077] In some embodiments, the dissolving step includes stirring at or above 200 rpm, such as 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm, 300 rpm, 310 rpm, 320 rpm, 330 rpm, 340 rpm, 350 rpm, 360 rpm, 370 rpm, 380 rpm, 390 rpm, 400 rpm, 410 rpm, 420 rpm, 430 rpm, 440 rpm, 450 rpm, 460 rpm, 470 rpm, 480 rpm, 490 rpm, 500 rpm, 510 rpm, 520 rpm, 530 rpm, 540 rpm, 550 rpm, 560 rpm, 570 rpm, 580 rpm, 590 rpm, 600 rpm, 610 rpm, 620 rpm, 630 rpm, 640 rpm, 650 rpm, 660 rpm, 670 rpm, 680 rpm, 690 rpm, 700 rpm, 710 rpm, 720 rpm, 730 rpm, 740 rpm, 750 rpm, 760 rpm, 770 rpm, 780 rpm, 790 rpm, 800 rpm, 810 rpm, 820 rpm, 830 rpm, 840 rpm, 850 rpm, 860 rpm, 870 rpm, 880 rpm, 890 rpm, 900 rpm, 910 rpm, 920 rpm, 930 rpm, 940 rpm, 950 rpm, 960 rpm, 970 rpm, 980 rpm, 990 rpm, or 1000 rpm. In some embodiments, the dissolving step includes stirring the first polyethylene-containing solution at or above 200 rpm.

[0078] Purification

[0079] The process for purifying recycled polyethylene includes contacting the first polyethylene -containing solution with an adsorption media. The contacting is at a temperature and at a pressure wherein the polyethylene in the polyethylene -containing solution remains dissolved in the solvent. The adsorption media may be an adsorption material that removes at least some of the compounds other than polyethylene from the first polyethylene -containing solution. Non-limiting examples of possible mechanisms include physisorption such as adsorption, absorption, size exclusion, ion exclusion, ion exchange, and other chemisorption mechanisms that may be apparent to those having ordinary skill in the art. In some aspects, the pigments and other contaminants commonly found recycled polyethylene and, therefore, may be present in the first polyethylene -containing solution may be polar compounds and may preferentially interact with the adsorption media, which may also be at least slightly polar. The polar-polar interactions are especially favorable when non-polar solvents, such as alkanes, are used as the solvent.

[0080] In some embodiments, the adsorption media is selected from the group consisting of inorganic substances, carbon-based substances, or mixtures thereof. In embodiments, the adsorption media may include a silicon oxide (silica), zeolite, activated alumina, aluminosilicates, montmorillonite clay, diatomaceous earth, fuller’s earth, activated carbon, or combinations thereof. In some embodiments, the adsorption media may include carbonbased substances such as anthracite coal, carbon black, coke, activated carbon, and mixtures thereof. In some embodiments, the adsorption media includes activated alumina, silica, zeolite, aluminosilicates, clay, diatomaceous earth, or combinations thereof. In some embodiments, the adsorption media includes activated alumina. In some embodiments, the activated alumina has an average particle size of less than 1.4 mm. In some embodiments, the activated alumina has a Na20 concentration of 0.4 wt.% to 4 wt.%, such as 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, or 4 wt.%. In some embodiments, the adsorption media includes silica. In some embodiments, the adsorption media includes attapulgite clay. In some embodiments, the attapulgite clay has an average particle size of less than 0.6 mm.

[0081] In some embodiments, the contacting is in a container or vessel for a specified amount of time while the adsorption media is agitated. In some embodiments, multiple vessels in series and / or in parallel containing adsorption media are contacted with the dissolved polymer. In some embodiments, the adsorption media is removed from the polyethylenecontaining solution via a solid-liquid separation step. Non-limiting examples of solid-liquid separation steps include filtration, decantation, centrifugation, and settling. In some embodiments, filtering is conducted in an axial or a radial flow direction using candle filters, rotating disks, or drum filters. In some embodiments, the filter may include a self-cleaning filter.

[0082] In some embodiments, the first polyethylene-containing solution may be passed through a stationary bed of adsorption media. In some embodiments, the height or length of the stationary bed of adsorption media is greater than 5 cm. In some embodiments, the height or length of the stationary bed of adsorption media is greater than 10 cm. In some embodiments, the height or length of the stationary bed of adsorption media is greater than 20 cm. In some embodiments, the adsorption media is replaced as needed to maintain a desired purity of polymer. In some embodiments, the adsorption media is regenerated and reused in the purification step. In some embodiments, the adsorption media is regenerated by fluidizing the adsorption media during a backwashing step.

[0083] In some embodiments, the contacting the first polyethylene-containing solution with adsorption media is at a temperature from 90°C to 210°C, such as 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or 210°C. In some embodiments, the contacting is at a temperature from 110°C to 200°C, such as 110°C to 160°C, 110°Cto 150°C, 110°Cto I40°C, 120°C to 200°C, 130°C to 200°C, 140°C to 200°C, 150°Cto 170°C, or 110°C to 180°C. In some embodiments, the process for purifying recycled polyethylene uses cyclohexane as the solvent and includes contacting the first polyethylenecontaining solution with adsorption media at a temperature from 130°C to 180°C, such as 130°C to 160°C, 130°C to 150°C, 130°C to 140°C, 130°C to 170°C, 130°C to 160°C, 140°C to 180°C, 150°C to 180°C, or 150°C to 170°C.

[0084] In some embodiments, the process for purifying recycled polyethylene uses cyclohexane as the solvent and includes contacting the first polyethylene-containing solution with adsorption media at a pressure from 150 psi to 1600 psi or at least any one of, at most any one of, equal to any one of, or between any two of 150 psi, 160 psi, 170 psi, 180 psi, 190 psi, 200 psi, 210 psi, 220 psi, 230 psi, 240 psi, 250 psi, 260 psi, 270 psi, 280 psi, 290 psi, 300 psi, 310 psi, 320 psi, 330 psi, 340 psi, 350 psi, 360 psi, 370 psi, 380 psi, 390 psi, 400 psi, 410 psi, 420 psi, 430 psi, 440 psi, 450 psi, 460 psi, 470 psi, 480 psi, 490 psi, 500 psi, 510 psi, 520 psi, 530 psi, 540 psi, 550 psi, 560 psi, 570 psi, 580 psi, 590 psi, 600 psi, 610 psi, 620 psi, 630 psi, 640 psi, 650 psi, 660 psi, 670 psi, 680 psi, 690 psi, 700 psi, 710 psi, 720 psi, 730 psi, 740 psi, 750 psi, 760 psi, 770 psi, 780 psi, 790 psi, 800 psi, 810 psi, 820 psi, 830 psi, 840 psi, 850 psi, 860 psi, 870 psi, 880 psi, 890 psi, 900 psi, 910 psi, 920 psi, 930 psi, 940 psi, 950 psi, 960 psi, 970 psi, 980 psi, 990 psi, 1000 psi, 1050 psi, 1100 psi, 1150 psi, 1200 psi, 1250 psi, 1300 psi, 1350 psi, 1400 psi, 1450 psi, 1500 psi, 1550 psi, or 1600 psi.

[0085] In some embodiments, the first polyethylene-containing solution used in the contacting step includes polyethylene is dissolved at a mass percent concentration up to 10%. In some embodiments, the first polyethylene -containing solution used in the contacting step includes polyethylene is dissolved at a mass percent concentration up to 20%. In some embodiments, the first polyethylene-containing solution used in the contacting step includes polyethylene is dissolved at a mass percent concentration up to 30%. In some embodiments, the first polyethylene-containing solution used in the contacting step includes polyethylene is dissolved at a mass percent concentration up to 40%.

[0086] Separation

[0087] The process for purifying recycled polyethylene includes separating a purified recycled polyethylene from the second polyethylene-containing solution. In some embodiments, the separating is at a temperature and at a pressure wherein the polymer precipitates from solution and is no longer dissolved in the solvent. In some embodiments, the precipitation of the purified recycled polyethylene from the solvent is accomplished by reducing the pressure at a fixed temperature. In some embodiments, the precipitation of the purified recycled polyethylene from the solvent is accomplished by increasing or decreasing the temperature at a fixed pressure. In some embodiments, the precipitation of the purified recycled polyethylene from the solvent is accomplished by reducing both the temperature and pressure. In some embodiments, the solvent can be partially or completely converted from the liquid to the vapor phase by controlling the temperature and pressure to precipitate out the purified recycled polyethylene from solvent. In some embodiments, the separation of the precipitated purified recycled polyethylene is accomplished by a process of liquid-liquid or liquid-solid separation.

[0088] In some embodiments, the separating of the precipitated purified recycled polyethylene is accomplished by using a secondary anti-solvent having an RED > 1.1. In some embodiments, the anti-solvent is acetone.

[0089] In some embodiments, the process for purifying recycled polyethylene includes separating the purified polyethylene from the recycled polyethylene -containing solution at a temperature and a pressure wherein the polyethylene precipitates from solution. In some embodiments, the solvent is cyclohexane and the separating is at a temperature from 0°C to 270°C, such as 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, or 270°C. In some embodiments, the solvent is cyclohexane and the separating is at a temperature between 50°C and 260°C. In some embodiments, the solvent is cyclohexane and the separating is at a temperature between 100°C and 270°C.

[0090] In some embodiments, the solvent is cyclohexane and the separating is at a pressure from 0 psi to 4000 psi, such as 0 psi, 50 psi, 100 psi, 200 psi, 300 psi, 400 psi, 500 psi, 600 psi, 700 psi, 800 psi, 900 psi, 1000 psi, 1100 psi, 1200 psi, 1300 psi, 1400 psi, 1500 psi, 1600 psi, 1700 psi, 1800 psi, 1900 psi, 2000 psi, 2100 psi, 2200 psi, 2300 psi, 2400 psi, 2500 psi, 2600 psi, 2700 psi, 2800 psi, 2900 psi, 3000 psi, 3100 psi, 3200 psi, 3300 psi, 3400 psi, 3500 psi, 3600 psi, 3700 psi, 3800 psi, 3900 psi, or 4000 psi. In some embodiments, the solvent is cyclohexane and the separating is at a pressure between 50 psi and 2,000 psi. In some embodiments, the solvent is cyclohexane and the separating is at a pressure between 75 psi and 1,000 psi.

[0091] Pretreating

[0092] In some aspects, the process for purifying recycled polyethylene further comprises pretreating the recycled polyethylene prior to the dissolving step. In some embodiments, the pretreating may include soaking and / or swelling the recycled polyethylene in a pretreatment solvent. In embodiments, the pretreatment solvent comprises a cycloalkane with a boiling point of 45 to 120°C (e.g., cyclohexane, cyclopentane), an aliphatic alkane with a boiling point of 35 to 100°C (e.g., pentane, hexane, heptane), an isoparafmic solvent with a boiling point of 25 to 100°C (e.g., isohexane, isopentane, a isoparaffmic hydrocarbon fluid such as ISOPAR® C or ISOPAR E), an aromatic with a boiling point of 110 to 150°C (e.g., xylene, toluene), an alcohol with a boiling point of 60 to 100°C (e.g., methanol, ethanol, propanol), an ether with a boiling point of -30 to 30°C (e.g. diethyl ether, dimethyl ether), a cyclic ether with a boiling point of 60 to 80°C (e.g., tetrahydrofuran, dioxolane), an ester with a boiling point of 50 to 80°C (e.g. methyl acetate, ethyl acetate), an acid (e.g., acetic acid), water, carbon dioxide, and / or a combinations thereof.

[0093] In some embodiments, the pretreating further includes removing the pretreatment solvent after the soaking and / or swelling to provide a soaked recycled polyethylene, and further purifying the soaked recycled polyethylene through solid-liquid extraction, filtration, or a combination thereof. In some embodiments, the pretreating comprises solid-liquid extraction, filtration, or a combination thereof. In embodiments including the pretreating step, the recycled polyethylene used in the dissolving step is the polyethylene obtained after the pretreating step, such as the soaked recycled polyethylene.

[0094] In some embodiments, the pretreating includes extracting the recycled polyethylene with a supercritical fluid or subcritical fluid. In some embodiments, the extracting includes contacting the recycled polyethylene with a supercritical fluid and / or subcritical fluid to obtain an extracted recycled polyethylene. In embodiments including the extraction step, the recycled polyethylene used in the dissolving step is the extracted recycled polyethylene. In some embodiments, the supercritical fluid and / or the subcritical fluid comprises a cycloalkane having a boiling point of 45 °C to 120°C, an aliphatic alkane having a boiling point of 35 °C to 100°C, an isoparafinic solvent having aboiling point of 25°C to 100°C, an aromatic having a boiling point of 110°C to 150°C, an alcohol having a boiling point of 60°C to 100°C, an ether having a boiling point of -30°C to 30°C, a cyclic ether having a boiling point of 60°C to 80°C, an ester having a boiling point of 50°C to 80°C, an acid, water, and / or carbon dioxide. In some embodiments, the supercritical fluid and / or the subcritical fluid is dimethylether or carbon dioxide. In some embodiments, the supercritical fluid is carbon dioxide. In some embodiments, the supercritical fluid further includes ethanol. In some embodiments, the supercritical fluid further includes cyclohexane.

[0095] In some embodiments, the extracting step comprises extracting recycled polyethylene at a temperature from 100°C to 220°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, or 220°C and at a pressure from 100 psi to 1500 psi, such as 100 psi, 200 psi, 300 psi, 400 psi, 500 psi, 600 psi, 700 psi, 800 psi, 900 psi, 1000 psi, 1100 psi, 1200 psi, 1300 psi, 1400 psi, or 1500 psi. The Purified Recycled Polyethylene

[0096] The purified recycled polyethylene produced in the disclosed process may have less than 1.5 wt.% ash, such as less than 0.001 wt.%, 0.002 wt.%, 0.003 wt.%, 0.004 wt.%, 0.005 wt.%, 0.006 wt.%, 0.007 wt.%, 0.008 wt.%, 0.009 wt.%, 0.01 wt.%, 0.02 wt.%, 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, 0.06 wt.%, 0.07 wt.%, 0.08 wt.%, 0.09 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, or 1.5 wt.% as quantified by thermogravimetric analysis; less than 240 ppm, such as less than 10 ppm, less than 20 ppm, less than 30 ppm, less than 40 ppm, less than 50 ppm, less than 60 ppm, less than 70 ppm, less than 80 ppm, less than 90 ppm, less than 100 ppm, less than 110 ppm, less than 120 ppm, less than 130 ppm, less than 140 ppm, less than 150 ppm, less than 160 ppm, less than 170 ppm, less than 180 ppm, less than 190 ppm, less than 200 ppm, less than 210 ppm, less than 220 ppm, less than 230 ppm, or less than 240 ppm, of antioxidants such as (2,4-di-tert-butyl-phenyl)-phosphite, octadecyl P~ (3,5- di-tert-butyl-4-hydroxy phenyl)-propionate, pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate), and sumilizer GP; less than 10 ppm of slip agents such as cis- 13-docosenamide, (Z)-docos-13-enamide, and N,N'-(ethane-l,2-diyl)di(octadecanamide).

[0097] The purified recycled polyethylene provided by the disclosed process may have: less than 1.5 wt.% ash, such as less than 0.001 wt.%, less than 0.002 wt.%, less than 0.003 wt.%, less than 0.004 wt.%, less than 0.005 wt.%, less than 0.006 wt.%, less than 0.007 wt.%, less than 0.008 wt.%, less than 0.009 wt.%, less than 0.01 wt.%, less than 0.02 wt.%, less than 0.03 wt.%, less than 0.04 wt.%, less than 0.05 wt.%, less than 0.06 wt.%, less than 0.07 wt.%, less than 0.08 wt.%, less than 0.09 wt.%, less than 0. 1 wt.%, less than 0.2 wt.%, less than 0.3 wt.%, less than 0.4 wt.%, less than 0.5 wt.%, less than 0.6 wt.%, less than 0.7 wt.%, less than 0.8 wt.%, less than 0.9 wt.%, less than 1 wt.%, less than 1.1 wt.%, less than 1.2 wt.%, less than 1.3 wt.%, less than 1.4 wt.%, or less than 1.5 wt.% ash; less than 240 ppm of antioxidants, such as less than 10 ppm, less than 20 ppm, less than 30 ppm, less than 40 ppm, less than 50 ppm, less than 60 ppm, less than 70 ppm, less than 80 ppm, less than 90 ppm, less than 100 ppm, less than 110 ppm, less than 120 ppm, less than 130 ppm, less than 140 ppm, less than 150 ppm, less than 160 ppm, less than 170 ppm, less than 180 ppm, less than 190 ppm, less than 200 ppm, less than 210 ppm, less than 220 ppm, less than 230 ppm, or less than 240 ppm; and / or less than 50 ppm of slip agents, such as less than less than 5 ppm, less than 10 ppm, less than 15 ppm, less than 20 ppm, less than 25 ppm, less than 30 ppm, less than 35 ppm, less than 40 ppm, less than 45 ppm, or less than 50 ppm. In some embodiments, the purified recycled polyethylene provided by the processes disclosed herein may have a lightness value (L*) that is at least 5% improved, such as 5%,

[0098] 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%.

[0099] 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%.

[0100] 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%,

[0101] 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%.

[0102] 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%.

[0103] 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% improved, relative to the recycled polyethylene used to obtain the purified recycled polyethylene, wherein (L*) is defined by the International Commission on Illumination using films prepared using a Wabash-Genesis Press with a thickness of 320 pm.

[0104] In some embodiments, the purified recycled polyethylene provided by the processes disclosed herein may have an opacity value (O) that is at least 7 % improved (Orel), such as 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%,

[0105] 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%.

[0106] 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%,

[0107] 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%.

[0108] 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%.

[0109] 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% improved, over the (O) of the recycled polyethylene used to obtain the purified recycled polyethylene, using compression molded plaque with a thickness of 320 pm prepared using a Wabash-Genesis Press, as per ASTM D-1928-90.

[0110] In some embodiments, the purified recycled polyethylene provided by the processes disclosed herein may have a colour change improvement (AE*)3, of at least 30, wherein AE* is calculated as described later herein.

[0111] Test Methods

[0112] The colour and opacity / translucency of a polymer may be parameters that determine whether or not a polymer can achieve the desired visual aesthetics of an article manufactured from the polymer. Mechanically recycled polyethylene is often dark in color and opaque due to residual pigments, fillers, and other contaminations. Thus, color and opacity measurements are important parameters in determining the effectiveness of a process for purifying recycled polyethylene.

[0113] Lightness and opacity measurements may be conducted on plaques prepared by compressing molding 0.5 g of purified recycled polyethylene at 175°C / 2000 PSI, into a 320 pm-thick mold inserted between two MYLAR® backing using a Wabash-Genesis Series Compression Molding Press, as per ASTM DI 928-90 - Preparation of Compression - Molded Polyethylene Test Sheets and Test Samples.

[0114] The color improvement of the purified recycled polyethylene may be quantified according to International Commission on Illumination (CIE) L*, a*, b* three dimensional color space. As such, L* represents a measure of lightness of the sample, where black is defined as L* = 0 and white as L* = 100. Reported lightness improvements ( / IL*) were calculated as per Equation 1.

[0115] AL* =(L2~L1)X 100 (Eq. 1)

[0116] Li where, Ln* indicates level of light to dark region of the color-space, in which n = 1 & 2 for parent and purified sample, respectively.

[0117] Product appearance improvement may also be captured by quantifying color change ( E*). All colorimetric measurements were conducted using a BYK spectro-guide 45 / 0 gloss colorimeter. In all cases, the WE373-CIE method was used. All lightness (L*) measurements were conducted using the CIELab color index.

[0118] Color changes ( E*) were calculated as per Equation 2: where, Ln* indicates level of light to dark, an* indicates red to green region of the color-space, b* indicates yellow to blue region of the color-space, in which n = 1 & 2 for parent (that is, the source recycled polyethylene or recycled polyethylene feedstock) and purified sample, respectively.

[0119] Recycled polyethylene purity or appearance improvement may also be assessed by comparing the opacity of a purified polyethylene sample to that of the parent material. Opacity may be calculated from the ratio of the reflectance of a prepared sample backed by a black substrate (Yb[ack) to the reflectance when it is backed by a white substrate (Ywflite), as per Equation 3 : 100 (Eq. 3)

[0120] Reported relative opacity improvements (AOre() were calculated as per Equation 4: 100 (Eq. 4) Where, Onindicates level of light to dark region of the color-space, in which n = 1 & 2 for parent and purified sample, respectively.

[0121] Similarly, reported absolute opacity improvements (A0a£)S) were calculated as per Equation 5 : abs= 02- 0 (Eq. 5)

[0122] Where, 0nindicates level of light to dark region of the color-space, in which n = 1 & 2 for parent and purified sample, respectively.

[0123] Residual slip agents content was quantified by Gas Chromatography on a Agilent 7890 Gas Chromatographs equipped with programmable temperature on-column injector and nitrogen chemiluminescence detector and DB-5HT column (30 m length, 0.250 mm diameter, 0.10 pm film thickness). Calibration curve for Crodamide ER were obtained between 20 to 2000 ppm to ensure linearity is maintained over the range of interest. For all slip agents quantification, the rPE resin sample (2 g) were ground prior to being extracted in Carbon disulfide (15 mb) for 48 hours under ambient conditions in a sample holder rotating at 10 RPM. Following the extraction, an aliquot (1.0 pL) was collected from the supernatant and injected onto the cool-on column. The limit of detection (LOD) associated with this procedure is about 3 ppm, while limit of quantification (LOQ) is about 10 ppm.

[0124] Residual antioxidants content was quantified by High Performance Liquid Chromatography on an Agilent 1200 HPLC equipped with a binary pump, thermostatted column compartment, and diode array detector. An Agilent ZORBAX RRHT Eclipse XDB- C8 reverse phase analytical column (4.6 x 50 mm, 1.8 pm) was used at 600 bar. Calibration curves for 11076, 11010, 1168 and TNPP were prepared in a concentration range of 40 to 1000 ppm to ensure linearity is maintained over the range of interest. For all antioxidants quantification, the rPE sample (1.5 g) was grinded prior being extracted in ethyl acetate (20 mb) in a Mars Xpress Model 230 / 60 microwave unit at 140°C for 30 minutes. An aliquot (3 pL) was subsequently collected and filtered (Agilent Captiva Econofilter polytetrafluoroethylene (PTFE) membrane, 13 mm diameter, 0.2 pm pore size) from the supernatant and injected on the column. Water (0-32 v / v %) : Acetonitrile (68-100 v / v%) was used as mobile phase. Selected antioxidants limit of quantification (LOQ) associated with this procedure are as follow: I168active = about 30 ppm, I168Oxidized = about 10 ppm, I 168hydroiyzed = about 10 ppm, 11076totai = about 10 ppm, 1101 Ototai = about 10 ppm, Sumilizer GPactive = about 10 ppm, Sumilizer GPoxidized = about 10 ppm, Sumilizer GPhydroiyzed = about 10 ppm, W705active = 15 ppm, W705active = 15 ppm. Non-combustible materials (also sometimes referred to as residual ash) was quantified by Thermogravimetric analysis (TGA) on a TA Instruments Model SDT 2960 Simultaneous

[0125] Thermal Analyzer equipped with a Nicolet Model 760 Magna FTIR Spectrometer. Weight and temperature calibrations were completed prior quantification experiments to ensure accuracy. Typical procedure consisted of loading a rPE sample (200 mg) onto a platinum sample pan prior to heating it to 800°C at a rate of 10°C / min under nitrogen atmosphere . The sample was subsequently maintained at 800°C for 10 minutes. The percentage residual mass was then calculated by comparing the initial mass of the sample to that of recorded after the

[0126] 800°C isothermal phase. Limit of quantification of residual ash associated with this method is about 0.1 wt.%. The residual ash difference (AResidual Ash) was calculated as percentage difference in residual ash compared to that of parent material measure by TGA, as per

[0127] Equation 6.

[0128] (Residual Ast^ — Residual Ash2)

[0129] AResidual Ash = (Eq. 6) Residual Asht

[0130] Residual metal content was quantified by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In all cases, samples were prepared via microwave digestion using an Anton Paar Multiwave Pro Microwave Reaction System. Typical procedure consisted of adding the sample rPE or purified-rPE (P-rPE) sample (200 mg) into a quartz digestion vessel. Millipore water (1 mL) and of concentrated nitric acid (6 mL) were then added to each digestion vessel. The samples were then microwave digested at a maximum of 200°C and 80 bar. After microwave digestion, each sample was diluted to a final volume of 45 mL with Millipore water. The final weight of each sample was then recorded. All samples were subsequently analyzed on an Agilent 7700x Inductively Coupled Plasma - Mass Spectrometer. Analysis was conducted in Spectrum Mode with five replicates per sample and 100 sweeps per replicate. Carrier gas with a flow rate of 1. 10 L / min, and a make-up gas with a flow rate of 0.10 L / min was used. Four gas modes were used in the collision / reaction cell to aid in the removal of interferences during analysis; H2 (hydrogen) with a flow rate of 5.5 mL / min, He (helium) with a flow rate of 5.3 mL / min, HEHe (high energy helium) with a flow rate of 10.0 mL / min, and no gas. The gas mode selected for analysis is element dependent. A reagent blank of 5% nitric acid was analyzed at the beginning of the run to establish background concentrations. Multi element standards ranging from 1 ppb to 5000 ppb in a nitric acid matrix (5 v / v %) were analyzed prior to sample analysis. Multi element QCs were periodically ran throughout the analysis (after calibration, middle of run and end of run). The QC concentration used is element dependent and is acceptable within + / - 15% of the expected concentration (specific QC information & results available upon request). Multi element QCs were periodically ran throughout the analysis (after calibration, middle of run and end of run) to confirm accuracy. A digestion blank was analyzed prior to all sample analysis. An internal standard containing Bi, Ge, In, Li, Sc, Tb, Y was run simultaneously with all calibration standards and samples.

[0131] EXAMPLES

[0132] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results. EXAMPLE 1

[0133] (Purification of Pelletized Post-Consumer rPE over Smaller Activated Alumina Separated by Anti-Solvent-Assisted Precipitation and Filtration)

[0134] In a nitrogen purged stirred pressurized vessel, colored recycled polyethylene (rPE) pellets (16.6 g) produced from municipal collection (EFS41100, Density = 0.942 g«cm'3, MFR (I21 / I2) = 36.6; EFS-plastics, Ontario, Canada) and cyclohexane (400 mL) were heated to about 160°C at about 300 psi. The resulting solution (about 5 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered a filter (Pore size 230 pm; Swagelok SS-8F-K4-230) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 165°C containing Activated Alumina 1 of particle size about 28 x 48 Tyler mesh (about 0.30-0.60 mm; BASF; Ludwigshafen, Germany). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. A solvent with RED > 1.1 for PE was then added to the purified rPE solution (Acetone; about 175 mL; RED = 1.2) resulting in efficient precipitation of the purified rPE. The precipitated purified rPE was then separated from the solvent mixture by vacuum filtration. The recovered purified rPE was then further devolatilized by heating it to 60°C under vacuum (about 25 mbar) for 48 hours (Mp-rPE = 11.8 g)-

[0135] Quantification of optical improvement following purification was calculated from colorimetric measurements on compression molded plaques of about 1 x 2 cm and thickness of about 320 pm, prepared as per ASTM DI 928-90 - Preparation of Compression - Molded Polyethylene Test Sheets and Test. Colorimetric measurements on purified rPE compared to that of measure from parent rPE EFS41100 (Baseline A) are summarized in Table 1. A marked decrease in opacity (AOrei) of 78% was recorded in addition to an improvement in Lightness (AL*) of 109% (see Experiment 11, Table 1). The efficiency of the purification process in removing colorant without additional pre-treatment (e.g. De-inking) is further captured by the high AE* value of 41.

[0136] In comparison, purification under conditions analogous to that of EXAMPLE 1, but in absence of purification media (see Experiment 21, Table 1), resulted in marked decreased opacity improvement (AOrei) of about 5%. Similarly, very limited AE* value of 5 was also recorded for the comparative sample, demonstrating the pivotal role of the adsorption media in the purification process.

[0137] Table 1. Summary of Optical Improvements for Purified of Recycled PE Isolated Using Anti-Solvent and Filtration, as per Example 1.

[0138] EXAMPLE 2

[0139] (Purification of Post-Consumer rPE Flexible Over Smaller Activated Alumina Separated by Anti-Solvent-Assisted Precipitation and Filtration)

[0140] In a nitrogen purged stirred pressurized vessel, shredded post-consumer PE film (16.4 g) containing 20 wt.% post-consumer colored PE film and cyclohexane (400 mb) were heated to about 160°C at about 400 psi. The resulting solution (about 5 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered a filter (Pore size 230 pm; Swagelok SS-8F-K4-230) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 170°C containing Activated Alumina 1 of particle size about 28 x 48 Tyler mesh (about 0.30-0.60 mm; BASF; Ludwigshafen, Germany). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. A solvent with RED > 1.1 for PE was then added to the purified rPE solution (Acetone; about 175 mb; RED = 1.2) resulting in efficient precipitation of the purified rPE. The precipitated purified rPE was then separated from the solvent mixture by vacuum filtration. The recovered purified rPE was then further devolatilized by heating it to 60°C under vacuum (about 25 mbar) for 48 hours (Mp-rPE = 12.2 g).

[0141] Optical improvement following purification was quantified analogously to that of Example 1. Colorimetric measurements on purified rPE (Experiment 14) compared to that of measured from parent post-consumer PE film (Baseline C) are summarized in Table 2. A marked decrease in opacity (AOrei) of 81% was recorded in addition to a significant improvement in Lightness ( Z*) of 62%. The efficiency of the purification process in removing colorant without additional pre-treatment (e.g. De-inking) is further captured by the high E* value of 36.

[0142] Interestingly, increasing colored content in post-consumer PE film starting material to about 40 wt.% (Baseline D) under analogous purification conditions resulted in ever greater optical improvement with decreased opacity improvement (AOrei) of 90% in addition to Lightness improvement ( Z*) of 56% and color change ( E*) value of 37 (see Experiment 15, Table 2). Figure 2 clearly shows the drastic appearance improvement of rPE following purification. Such high Lightness value (Z* = 90.3; Table 2) showcases the efficiency of the purification process allowing to attain purified rPE with appearance comparable to that of virgin PE. For instance, virgin PE (LDPE-AY821 (barefoot); NOVA Chemicals, Canada) has a Z* value of 90.3 and opacity of 9%, analogous to that to that of samples purified as per Experiment 15 (Table 2).

[0143] Table 2, Summary of Optical Improvements for Purified of Recycled PE Isolated Using

[0144] Anti-Solvent and Filtration, as per Example 2. EXAMPLE 3

[0145] (Purification of Post-Consumer rPE Pellets Over Larger Activated Alumina Separated by Anti-Solvent-Assisted Precipitation and Filtration)

[0146] In a nitrogen purged stirred pressurized vessel, the same parent rPE colored pellets (16.4 g) feedstock as EXAMPLE 1 (EFS41100, EFS-plastics, Ontario, Canada) and cyclohexane (400 mL) was heated to about 160°C at about 600 psi. The resulting solution (about 5 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered a filter (Pore size 230 pm; Swagelok SS-8F-K4-230) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 140°C containing Activated Alumina 2 of particle size about 7 x 14 Tyler mesh (about 1.4-2.8 mm; Axens; Rueil-Malmaison, France). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. A solvent with RED > 1. 1 for PE was then added to the purified rPE solution (Acetone; about 175 mL; RED = 1.2) resulting in efficient precipitation of the purified rPE. The precipitated purified rPE was then separated from the solvent mixture by vacuum filtration. The recovered purified rPE was then further devolatilized by heating it to about 60°C under vacuum (about 25 mbar) for 48 hours (Mp-rPE = 11.8 g).

[0147] Optical improvement following purification was quantified analogously to EXAMPLE 1. Interestingly, as shown in Table 3, a marked decrease in optical improvement was observed when using Activated Alumina 2 of larger particle size (1.4-2.8 mm). The significantly lower AL* value of 6% and AE* value of 10 show that appearance akin to that of virgin PE could not be achieved with activated alumina of larger particle size (> 1.4- 2.8 mm) under these experimental conditions.

[0148] Table 3, Summary of Optical Improvements for Purified of Recycled PE isolated Using Anti-Solvent and Filtration, as per Example 3. EXAMPLE 4

[0149] (Purification of Post-Consumer rPE Pellets Over Larger Silica Separated By Anti-Solvent- Assisted Precipitation and Filtration)

[0150] In a nitrogen purged stirred pressurized vessel, the same parent rPE colored pellets (16.5 g) feedstock as EXAMPLE 1 (EFS41100, EFS-plastics, Ontario, Canada) and cyclohexane (400 mL) was heated to about 160°C at about 1200 psi. The resulting solution (about 5 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered a filter (Pore size 230 pm; Swagelok SS-8F-K4-230) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 160°C containing Silica 1 of particle size about 6.5 x 12 Tyler mesh (about 1.7-3. 1 mm; Grace; Maryland, USA). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. A solvent with RED > 1.1 for PE was then added to the purified rPE solution (Acetone; about 175 mL; RED = 1.2) resulting in efficient precipitation of the purified rPE. The precipitated purified rPE was then separated from the solvent mixture by vacuum filtration. The recovered purified rPE was then further devolatilized by heating it to 60°C under vacuum (about 25 mbar) for 48 hours (Mp-rPE = 12.9 g).

[0151] Optical improvement following purification was quantified analogously to that of EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 5) compared to that of measure from parent post-consumer PE film (Baseline A) are summarized in Table 4. An opacity improvement (AOrei) value of 43%, a AL* value of 33% and AE* value of 21 were recorded following purification. However, the lower L* value of 43.1 compared to 90.3 for virgin PE virgin PE (LDPE-AY821; NOVA Chemicals) shows that appearance akin to that of virgin PE was not achieved with silica of larger particle size (> 1.7-3.1 mm).

[0152] Table 4, Summary of Optical Improvements for Purified of Recycled PE Isolated Using Anti-Solvent and Filtration, as per Example 4. EXAMPLE 5

[0153] (Purification of Post-Consumer rPE Pellets Over Smaller Silica Separated By Anti-Solvent- Assisted Precipitation and Filtration)

[0154] The rPE feedstock of EXAMPLE 1 was purified using the same conditions as in EXAMPLE 4. However, Silica 2 (Grace; Maryland, USA) of particle size of about 40 Tyler Mesh (about 0.4 mm) was used for purification.

[0155] Optical improvement following purification was quantified analogously to Example 1. Colorimetric measurements on purified rPE (Experiment 20) compared to that of measured from parent post-consumer Colored rPE Pellets (Baseline A) are summarized in Table 5. As can be seen, a marked decrease in opacity (AOrei) of 88% was recorded in addition to an improvement in Lightness (AL*) of 142%. The efficiency of the purification process in removing colorant without additional pre-treatment (e.g. De-inking) is further captured by the high AE* value of 52. The high L* value of 84 shows that appearance akin to that of virgin PE could be achieved with silica of smaller particle size (about 0.4 mm).

[0156] Table 5 , Summary of Optical Improvements for Purified of Recycled PE Isolated Using Anti-Solvent and Filtration, as per Example 5.

[0157] EXAMPLE 6

[0158] (Purification of Post-Consumer rPE Pellets Over Smaller Activated Carbon Separated by Anti-Solvent-Assisted Precipitation and Filtration)

[0159] The same rPE feedstock used for EXAMPLE 1 (16.4 g) was purified using the analogous conditions as in EXAMPLE 1. However, Activated Carbon 1 (Sigma- Aldrich, Missouri, USA) of particle size of about 40 Tyler Mesh (about 0.4 mm) was used for purification (Mp-rPE = 3.4 g).

[0160] Optical improvement following purification was quantified analogously to EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 12) compared to that of measure from parent post-consumer PE (Baseline A) compression molded plaque are summarized in Table 6. A marked decrease in opacity (AOrei) of 80%, in addition to an improvement in Lightness (AL*) of 137% were recorded. The efficiency of the purification process in removing colorant without additional pre-treatment (e.g. De-inking) is further captured by the high AE* value of 50. The high L* value of 82 shows that appearance similar to that of virgin PE could be achieved with activated carbon of smaller particle size (about 0.4 mm).

[0161] Interestingly, the same rPE feedstock used for EXAMPLE 1 (16.4 g) was purified using about the same conditions as in EXAMPLE 6. However, Activated Carbon 2 (EMD Chemicals Inc., New Jersey, USA) of particle size of about 4 x 12 Tyler Mesh (about 1.7-4.8 mm) was used for purification (Mp-rPE = 3.8 g). Optical improvements following purification was quantified analogously to that of EXAMPLE 1.

[0162] A steep decrease in opacity (AOrei) of 80% was recorded in addition to an improvement in Lightness (AL*) of 64% and of color difference (AE*) value of 29 (See Experiment 13, Table 6). However, as shown in Table 6 and similarly to EXAMPLE 3 and EXAMPLE 4, purification using solid media with larger particle size (> about 7 x 14 Tyler mesh) resulted marked decrease in appearance improvement. Further, the marked reduced yield for purification conducted using activated carbon that in addition to the media particle size, the affinity of the PE for the purification media is also important to consider. Without being bound by any particular theory, compared to silica and activated alumina, PE and activated carbon may interact more strongly due to favorable hydrophobic interactions (Van der Waal’s forces) resulting in greater adherence of PE to the solid media and significant loss in P-rPE yield under analogous conditions.

[0163] Table 6, Summary of Optical Improvements for Purified of Recycled PE Isolated Using Anti-Solvent and Filtration, as per Example 6. EXAMPLE 7

[0164] (Purification of Post-Consumer rPE Pellets Over Mixture of Silica and Activated Alumina Separated by Anti-Solvent-Assisted Precipitation and Filtration)

[0165] The same rPE feedstock used for EXAMPLE 1 (16.7 g) was purified using analogous conditions as in EXAMPLE 1. However, Silica 2 (Grace; Maryland, USA) of particle size of about 40 Tyler Mesh (about 0.4 mm) and Activated Alumina 1 of particle size about 28 x 48 Tyler mesh (about 0.30-0.60 mm; BASF; Ludwigshafen, Germany) were used in 1: 1 mass ratio (Mp-rPE = 8.4 g).

[0166] Optical improvements following purification were quantified analogously to that of EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 23) compared to that of measure from parent post-consumer PE compression molded plaque (Baseline A) are summarized in Table 7. This mixture of activated alumina and silica resulted in a decrease in opacity (AO) of 91%, the highest recorded for this feedstock. Similarly, an improvement in Lightness (AL*) of 151% was also recorded. The efficiency of the purification process in removing colorants and other impurities without additional pre-treatment (e.g. De-inking) is further captured by the high AE* value of 54. The high L* value of 87 shows that appearance similar to that of virgin PE could be achieved with a mixture of activated alumina and silica. Table 7, Summary of Optical Improvements for Purified of Recycled PE Isolated Using

[0167] Anti-Solvent and Filtration, as per Example 7.

[0168] EXAMPLE 8

[0169] (Purification of Granulated Post-Consumer rPE Over Smaller Activated Alumina Separated by Evaporation)

[0170] Although significant rPE appearance improvement can be achieved by adsorption purification and subsequent addition of anti-solvent (RED >1.1; e.g. EXAMPLES 1, 2, 5, 6, & 7), in some instances, it may be beneficial, to isolate the purified rPE without the need of a second solvent and / or filtration. Instead, the purified rPE (P-rPE) may be separated from the solvent by reducing operating pressure and / or increase temperature. In some cases, it may be beneficial to further reduce pressure below atmospheric pressure to reduce heating requirements to attain acceptable residual volatiles concentration. To exemplify this, mixed colors rHDPE granules, (16.6 g, 10MFI HD MIX COLOR, Kal-Polymers, Ontario, Canada, Density = 0.948 g«cm'3, MFR (I21 / I2) = 36.2) were added to a nitrogen purged pressurized vessel along with cyclohexane (400 mL) prior being heated to about 180°C at about 400 psi. The resulting solution (about 5 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered filter (Pore size 440 pm; Swagelok SS-8F-K4-440) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 180°C containing activated alumina of particle size about 28 x 48 Tyler mesh (about 0.30-0.60 mm; BASF; Ludwigshafen, Germany). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. The recovered purified rPE was finally separated from volatiles using a vacuum centrifuge (Genevac, Ipswich, UK) at about 40°C and 78 mbar for about 6 hours at 1050 RPM (Mp-rPE = 15.4 g).

[0171] Optical improvement following purification was quantified analogously to EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 24) compared to that of measure from parent post-consumer rHDPE granules (Baseline E) are summarized in Table 8. Interestingly, this simplified purification process resulted in significant a decrease in opacity (AOrei) of 43% as well as a lightness improvement (z / Z*) of 21%. The lower AL* recorded is due to the specific additives and colorants used for this rHDPE feedstock. As shown in Table 8, the lighter or brighter color of this rHDPE feedstock results in a higher lightness value (L* = 67.8) compared to the dark blue Colored rPE pellets (Z* = 34.7) used in Example 1, decreasing the maximum potential AL*. Similar observations are made regarding opacity improvement due to the comparatively lower opacity of this particular parent rHDPE feedstock (Opacityparent IHDPE = 44%). As such, for this feedstock, the efficiency of the purification process in removing colorant without additional pre-treatment (e.g. Deinking) is better captured by the high AE* value (> 30) of 42, reflecting color change. The high Z* value of 84 shows that appearance similar to that of virgin PE could be achieved. Table 8, Summary of Optical Improvements for Purified of Recycled PE Isolated by Evaporation, as per Example 8.

[0172] EXAMPLE 9

[0173] (Purification of Granulated Post-Consumer rPE Over Intermediate Size Activated Alumina Separated by Evaporation)

[0174] Mixed colors rHDPE granules, (about 69.1 g, 10MFI HD MIX COLOR, Kal- Polymers, Ontario, Canada, Density = 0.948 g«cm'3, MFR (I21 / I2) = 36.2) were added to a nitrogen purged pressurized vessel along with cyclohexane (about 800 mb) prior being heated to about 165°C at about 600 psi. The resulting solution (about 10 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered filter (Pore size 440 pm; Swagelok SS-8F-K4-440) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 165°C containing Activated Alumina 4 of particle size about 14 x 28 Tyler mesh (about 0.60-1.41 mm; BASF; Ludwigshafen, Germany). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. The recovered purified rPE was finally separated from volatiles and devolatilized using a vacuum centrifuge (Genevac, Ipswich, UK) at about 40°C and 78 mbar for about 6 hours at 1050 RPM (Mp-rPE = 68.6 g).

[0175] Optical improvement following purification was quantified analogously to that of EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 36) compared to that of measured from parent post-consumer rHDPE (Baseline E) are summarized in Table 9. The high AE* value of 36 and decrease in opacity (AOrei) of 40% show that purification over medium size activated alumina (< 7 x 14 & > 28 x 48 Tyler Mesh) can result in significant appearance improvement.

[0176] In comparison, the same rPE feedstock used for EXAMPLE 9 (69.9 g) was purified using the same conditions. However, activated alumina of particle size about 7 x 14 Tyler mesh (about 1.41-2.83 mm; BASF; Ludwigshafen, Germany) was used as purification media (Mp-rPE = 61.6 g). Optical improvement following purification was quantified analogously to EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 31) compared to that of measure from parent post-consumer PE film are summarized in Table 9. As can be seen, using activated alumina of larger particle size (1.41-2.83 mm) did not result in a high AE* value (AE* < 30).

[0177] Table 9, Summary of Optical Improvements for Purified of Recycled PE Isolated by

[0178] Evaporation, as per Example 9.

[0179] “Recorded negative AL* is ascribed to change in sample color uniformity following dissolution-precipitation and concomitant negligible colorants removal.

[0180] EXAMPLE 10

[0181] (Purification of Granulated Post-Consumer rPE Over Zeolites Separated by Evaporation)

[0182] Although solid media particle size is a critical parameter to consider when selecting solid media for rPE purification to realize significant color change in P-rPE (AE* > 30), composition and associated pore size distribution must also be selected adequately. To illustrate this, the same rPE feedstock (69.7 g) as that of used in EXAMPLE 9 was purified under the same conditions. However, zeolite 1 of particle size about 14 x 28 Tyler mesh (about 0.60-1.19 mm; Evonik; Ludwigshafen, Germany) was used as solid media (Mp-rPE = 63.2 g). Optical improvement following purification was quantified analogously to that of EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 35) compared to that of measured from parent post-consumer rHDPE (Baseline E) are summarized in Table 10. As can be seen, contrarily to activated alumina of the same particle size (EXAMPLE 9; Experiment 36) neither significant color change (AE* > 30) nor lightness improvement (AL*) was achieved when zeolite of particle size of about 14 x 28 Tyler mesh (about 0.60-1. 19 mm) was used as solid media. Table 10. Summary of Optical Improvements for Purified of Recycled PE Isolated by Evaporation, as per Example 10.

[0183] “Recorded negative AL* is ascribed to change in sample color uniformity following dissolution-precipitation and concomitant limited colorants removal.

[0184] EXAMPLE 11

[0185] (Purification of Granulated Post-Consumer rPE Over Clay Separated by Evaporation)

[0186] Mixed colors rHDPE granules, (69.4 g, 10MFI HD MIX COLOR, Kal-Polymers, Ontario, Canada, Density = 0.948 g«cm'3, MFR (I21 / I2) = 36.2) were added to a nitrogen purged pressurized vessel along with cyclohexane (800 mb) prior being heated to about 180°C at about 600 psi. The resulting solution (about 10 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered filter (Pore size 440 pm; Swagelok SS-8F-K4-440) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 180°C containing clay (attapulgite) of particle size about 30 x 60 Tyler mesh (about 0.25-0.60 mm; Clariant; Muttenz, Switzerland). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. The recovered purified rPE was finally separated from volatiles and devolatilized using a vacuum centrifuge (Genevac, Ipswich, UK) at about 40°C and 78 mbar for about 6 hours at 1050 RPM (Mp-rPE = 51.5 g).

[0187] Optical improvement following purification was quantified analogously to EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 29) compared to that of measured from parent post-consumer rHDPE (Baseline E) are summarized in Table 11. The high AE* value of 37 and opacity (AOrei) of 53% show that rPE purification over clay can result in significant appearance improvement. Table 11. Summary of Optical Improvements for Purified of Recycled PE Isolated by

[0188] Evaporation, as per Example 11.

[0189] EXAMPLE 12 (Residual Non-Polyethylene Content Improvements)

[0190] Non-combustible materials, residual antioxidants, and residual slip agents were quantified prior (parent rPE) and after purification, as summarized in Tables 12-16.

[0191] Thermogravimetric analysis (TGA) was performed to quantify the non-combustible materials (also sometimes referred to as residual ash) in following purification compared to that of parent feedstock. Table 12 summarizes residual non-combustibles highlighting significant improvement in residual inorganic content for purified recycled polyethylene samples, where recorded decrease in residual ash (AResidual Ash) were as much as 94%.

[0192] Table 12, Quantification of Residual Ash for Purified Recycled PE Isolated by Anti-

[0193] Solvent-Assisted Precipitation and Filtration.

[0194] ‘Formerly sold by NOVA Chemicals (Canada). EX-PCR-NC4 has a melt index (190°C / 2.16 kg) of 1.0 g / 10 min, as determined by ASTM D 1238 and a density of 0.925 g / cm3as determined by ASTM D 792. It is greater than 99 wt.% post-consumer recycled LLDPE / LDPE resin sourced from distribution centers.

[0195] Table 13, Summary of Residual Antioxidants3for Purified Recycled PE Isolated by Anti- Solvent-Assisted Precipitation and Filtration.

[0196] “Residual antioxidants were quantified by High-performance liquid chromatography. Table 13 provides data showing improvement in residual antioxidants content with removal of many residual antioxidant to below the limit of quantification (LOQ) of the high-performance liquid chromatography experiments. Selected antioxidants limit of quantification (LOQ) associated with this procedure are as follow: 1168 Active = 30 ppm, 1168 Oxidized = 10 ppm, 1168 Hydrolyzed = 10 ppm, 11076 Total = 10 ppm, 11010 Total = 10 ppm.bCyclohexane was used as dissolution solvent in all cases.

[0197] Table 14, Summary of Residual Antioxidants for Purified Recycled PE Isolated by

[0198] Evaporation, as per Example 8. aResidual antioxidants were quantified by High-performance liquid chromatography. Table 14 provides data showing improvement in residual antioxidants content with removal of many residual antioxidant to below the limit of quantification (LOQ) of the high-performance liquid chromatography experiments. Selected antioxidants limit of quantification (LOQ) associated with this procedure are as follow: 1168 Active = 30 ppm, 1168 Oxidized = 10 ppm, 11076 Total = 10 ppm.,b[rPE] = 5 wt.%, “Adsorber bed skin temperature = 165°C. Residual slip agents were quantified by Gas chromatography-mass spectrometry. Table

[0199] 15 & Table 16 provides examples of recorded improvement in residual slip agents content with removal of residual slip agents to levels below the limit of detection (< LOD) by gas chromatography-mass spectroscopy experiments. The limit of detection (LOD) associated with this quantification procedure is 3 ppm. Table 15, Summary of Residual Slip Agent for Purified Recycled PE Isolated Using Anti-

[0200] Solvent-Assisted Precipitation and Filtration.

[0201] Table 16, Summary of Residual Slip Agent for Purified Recycled PE Isolated by Evaporation, as per Example 8. b[rPE] = 5 wt.%,cAdsorber bed skin temperature = 165 °C. Table 17, Summary of Operating Condition for Purification of rPE Isolated Using AntiSolvent and Filtration.

[0202] EXAMPLE 13 (Purification of Granulated Post-Consumer rPE Using Solvents Selected Based on RED Value)

[0203] Mixed colors rHDPE granules, (69.1 g, 10MFI HD MIX COLOR, Kal-Polymers, Ontario, Canada, Density = 0.948 g«cm'3, MFR (I21 / I2) = 36.2) was added to a nitrogen purged pressurized vessel along with cyclohexane (800 mL) prior being heated to about 180°C at about 600 psi. The resulting solution (about 10 wt.% rPE) was then left under mechanical stirring (about 300 rpm) for about 60 minutes. The solution was then allowed to flow through a sintered filter (Pore size 440 un; Swagelok SS-8F-K4-440) followed by a sample cylinder (Swagelok 316L-HDF4-300) heated to a skin temperature of about 180°C containing activated alumina of particle size about 14 x 28 Tyler mesh (about 0.60-1.41 mm; BASF; Ludwigshafen, Germany). The resulting purified rPE solution was then collected into a nitrogen purged pressurized vessel. The recovered purified rPE was finally separated from volatiles using a vacuum centrifuge (Genevac, Ipswich, UK) and devolatilized by heating it to about 40°C under at about 78 mbar for about 6 hours (Mp-rPE = 59.9 g).

[0204] Optical improvement following purification was quantified analogously to EXAMPLE 1. Colorimetric measurements on purified rPE (Experiment 40) compared to that of measured from parent post-consumer rHDPE (Baseline E) are summarized in Table 18. The high AE* value of 32 and relative decrease in opacity (AO) of 46% show that this purification using a solvent with RED < 0.8 (REDcyciohexane = 0.79) under reported operating conditions can result in significant appearance improvement (AE* > 30). Similarly, the same feedstock (10MFI HD MIX COLOR, Kai -Polymers, Ontario, Canada) was purified under the same operating conditions as that of EXAMPLE 13, using a solvent with a RED of 0.5 (RED0- xyiene = 0.50; Mp-rPE = 63.8 g). This also resulted in a high AE* value of 37 and relative decrease in opacity (AO) of 46% (see Experiment 45).

[0205] In comparison, purification of the same rPE feedstock used for EXAMPLE 13 (69.3 g), using the same conditions as in EXAMPLE 13. However, using 1,4-dioxane, a solvent with a RED slightly greater than 0.8 (REDi,4-Dioxane = 0.9), did not result in significant color improvement (AE* > 30; Table 17, Experiment 44). A significant decrease in yield (Mp-rPE = 47.0 g) under the same operating conditions was also observed. Accordingly, selecting isohexane, a solvent with greater RED (REDisohexane = 1.1) resulted in further drop in yield (Mp-rPE = 2.8 g)

[0206] Table 18, Summary of Optical Improvements for Purified of Recycled PE Isolated Using

[0207] Anti-Solvent and Filtration, as per Example 13.

[0208] EXAMPLE 14

[0209] (rPE Purification by Supercritical Fluid Extraction)

[0210] Although rPE purification over adsorption media can efficiently remove residual colorants, additives and putative degradation products, the limited capacity of the adsorption media must be overcome by regularly regenerating and ultimately discarding the adsorbent. As such, removing as much contaminants as possible prior to contacting the rPE with the adsorption media can extend the lifetime of the adsorption media and reduce associated environmental footprint. Accordingly, pretreatment of the recycled polyethylene was investigated. rPE samples were purified via supercritical fluid extraction experiments. Typical supercritical fluid extraction experiment consisted of loading rPE Mixed colors rPE granules, (35.0 g, 10MFI HD MIX COLOR, Kal-Polymers, Ontario, Canada, Density = 0.948 g«cm'3, MFR (I21 / I2) = 36.2) into a supercritical extractor (Supercritical Fluid Technologies Inc.; SFT-250). The reactor was subsequently sealed and purged with CO2. Once target temperature and reactor pressure was reached SCO2 flow was adjusted with a needle valve and the extraction allowed to proceed for 6 hours at a SCO2 flow of 5 L / min. Experiments conducted in presence of co-solvent (Ethanol) were split into a static and dynamic segment. During the static segment, the reactor was allowed to reach target experiment conditions under static CO2 pressure in presence of Ethanol (no continuous CO2 flow) for 3 hours. The second part involved using sCCh flow to push out the generated ethanol / sCCh extract followed by extraction with sCCh only (5 L / min) for an additional 3 hours. All extractions were conducted at 80°C. Selected experimental operating conditions are summarized in Table 18. As can be seen in Table 19, up to 87% of slip agents and 42% of antioxidants (AO) could be extracted in neat supercritical carbon dioxide (SCO2). Using ethanol as co-solvent did not improve extraction efficiency as only up to 28% of total AO could be removed in presence of ethanol. Notably, up to 80% of heavy metals could be extracted in neat SCO2 (Table 19). As can be seen in Table 20, this is of particular importance as adsorption purification alone could not quantitatively remove heavy metals, regardless of adsorption media and operating conditions selected. As such, considering the cumulative heavy metals extraction efficiency, combining supercritical fluid extraction to adsorption purification can provide much improved heavy metals removal compared to adsorption purification alone.

[0211] Table 19, Summary of Standard Operating Conditions for rPE Purification via SFE

[0212] Experiments.

[0213] Table 20, Quantification of Residual Antioxidant (IRGAFOS 168; 1168), Slip Agent (ASlip) and Heavy Metals (AHeavy Metals) of rPE Samples Compared to that of Purified via

[0214] Supercritical CO2 Extraction, as per Example 14.

[0215] 'Quantifed heavy metals: Chromium, arsenic, cadmium, mercury & lead; for feedstock and P-rPE.2Value was not measured. Table 21 , Quantification of Heavy Metals1(AHeavy Metals) of Parent rPE Feedstock

[0216] Compared to that of rPE Samples Purified, as per Example 14.

[0217] 'Quantifed heavy metals: Chromium, arsenic, cadmium, mercury & lead; for feedstock and P-rPE. Cyclohexane was used as solvent for all experiments

[0218] Other than where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and claims are approximations that can vary depending upon the desired properties, which the present disclosure desires to obtain. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0219] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0220] In addition, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” or “between 1 and 10” is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Non-limiting embodiments of the present disclosure include the following:

[0221] Embodiment A. A process for purifying recycled polyethylene, the process comprising: dissolving at least a portion of recycled polyethylene in a solvent to provide a first polyethylene-containing solution; contacting the first polyethylene -containing solution with an adsorption media to obtain a second polyethylene-containing solution; and separating a purified recycled polyethylene from the second polyethylene -containing solution; wherein the solvent has a boiling point higher than 70°C; and wherein a relative energy difference (RED) between the solvent and the polyethylene in the recycled polyethylene, calculated using Hansen Solubility Parameters, is less than or equal to 0.8.

[0222] Embodiment B. The process according to Embodiment A, wherein the RED is less than or equal to 0.5.

[0223] Embodiment C. The process according to Embodiment A, wherein the solvent is cyclohexane, xylenes, or a combination thereof.

[0224] Embodiment D. The process according to Embodiment A, wherein the solvent is cyclohexane.

[0225] Embodiment E. The process according to Embodiment A, wherein the solvent is xylenes.

[0226] Embodiment F. The process according to Embodiment A, B, C, D, or E, wherein the dissolving step is at a temperature between 90°C and 200°C.

[0227] Embodiment G. The process according to Embodiment A, B, C, D, E, or F, wherein the adsorption media comprises activated alumina, silica, zeolite, aluminosilicates, clay, diatomaceous earth, or combinations thereof.

[0228] Embodiment H. The process according to Embodiment A, B, C, D, E, or F, wherein the adsorption media comprises activated alumina.

[0229] Embodiment L The process according to Embodiment H, wherein the activated alumina has an average particle size of less than 1.4 mm.

[0230] Embodiment J. The process according to Embodiment A, B, C, D, E, or F, wherein the adsorption media comprises silica.

[0231] Embodiment K. The process according to Embodiment A, B, C, D, E, or F, wherein the adsorption media comprises attapulgite clay.

[0232] Embodiment L. The process according to Embodiment K, wherein the attapulgite clay has an average particle size of less than 0.6 mm. Embodiment M. The process according to Embodiment A, B, C, D, E, F, G, H, I, J,

[0233] K, or L, wherein one or more of the dissolving, contacting, and separating are at a pressure between 150 psi and 1600 psi.

[0234] Embodiment N. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, or L, wherein one or more of the dissolving, contacting, and separating are at a pressure between 300 psi and 1200 psi.

[0235] Embodiment O. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, or L, wherein the dissolving is at a pressure between 300 psi and 1200 psi.

[0236] Embodiment P. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K,

[0237] L, M, N, or O, wherein the separating is by liquid-liquid extraction or liquid-solid separation.

[0238] Embodiment Q. The process according Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, or O, wherein the separating comprises contacting the second polyethylenecontaining solution with an anti-solvent having an RED greater than 1.1.

[0239] Embodiment R. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, or Q, further comprising pretreating the recycled polyethylene prior to the dissolving.

[0240] Embodiment S. The process according to Embodiment R, wherein the pretreating comprises contacting the recycled polyethylene with a supercritical fluid.

[0241] Embodiment T. The process according to Embodiment S, wherein the supercritical fluid comprises dimethyl ether or carbon dioxide.

[0242] Embodiment U. The process according to Embodiment S, wherein the supercritical fluid is carbon dioxide.

[0243] Embodiment V. The process according to Embodiment S, T, or U, wherein the supercritical fluid further comprises ethanol.

[0244] Embodiment W. The process according to Embodiment S, T, or U, wherein the supercritical fluid further comprises cyclohexane.

[0245] Embodiment X. The process according to Embodiment R, wherein the pretreating comprises soaking and / or swelling the recycled polyethylene in a pretreatment solvent.

[0246] Embodiment Y. The process according to Embodiment X, wherein the pretreatment solvent comprises a cycloalkane with a boiling point of 45 to 120°C, an aliphatic alkane with a boiling point of 35 to 100°C, an isoparaffin with a boiling point of 25 to 100°C.

[0247] Embodiment Z . The process according to Embodiment X or Y, wherein the pretreating further comprises removing the pretreatment solvent after the soaking and / or swelling to provide a soaked recycled polyethylene, and further purifying the soaked recycled polyethylene through solid-liquid extraction, liquid-liquid extraction, filtration, or a combination thereof.

[0248] Embodiment AA. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, or Z, further comprising filtering the first polyethylene-containing solution prior to the contacting step.

[0249] Embodiment AB. The process according to Embodiment A, B, C, D, E, F, G, H, I, J,

[0250] K, L, M, N, O, P, Q, R, S, T, U, V, or W, wherein the first polyethylene-containing solution comprises up to 40 wt.% dissolved polyethylene.

[0251] Embodiment AC. The process according Embodiment A, B, C, D, E, F, G, H, I, J, K,

[0252] L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, or AB, wherein the purified recycled polyethylene has a lightness improvement, AL*, of at least 5% overthe recycled polyethylene.

[0253] Embodiment AD. The process according to Embodiment AC, wherein the lightness improvement (AL*) is at least 30%.

[0254] Embodiment AE. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, AB, AC, or AD, wherein the purified recycled polyethylene has an opacity improvement, AO, of at least 15% over the recycled polyethylene.

[0255] Embodiment AF. The process according to Embodiment E, wherein the opacity improvement is at least 40%.

[0256] Embodiment AG. The process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, AB, AC, AD, AE, or AF, wherein the purified recycled polyethylene has a colour improvement , AE, of at least 30.

[0257] Embodiment AH. A purified recycled polyethylene prepared by the process according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, AB, AC, AD, AE, AF, or AG.

[0258] Embodiment AE The purified recycled polyethylene of Embodiment AH, comprising: less than 1.5 wt.% ash; less than 240 ppm of antioxidants; and less than 50 ppm of slip agents cis-13-docosenamide, (Z)-docos-13-enamide, and N,N'-(ethane-l,2- diyl)di(octadecanamide) . References

[0259] (1) Hansen, C. M. Hansen Solubility Parameters: A User ’s Handbook, Second Edition, 2nd ed.; CRC Press: Boca Raton, 2007. https: / / doi.org / 10.1201 / 9781420006834.

[0260] (2) Surface Free Energy Components by Polar / Dispersion and Acid — Base Analyses; and Hansen Solubility Parameters for Various Polymers. https: / / www.accudynetest.com / polytable_02.html (accessed 2024-07-29).

[0261] (3) Ishikawa-Nagai, S.; Yoshida, A.; Sakai, M.; Kristiansen, J.; Da Silva, J. D. Clinical Evaluation of Perceptibility of Color Differences between Natural Teeth and AllCeramic Crowns. J. Dent. 2009, 37, e57-e63. Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims.

[0262] INDUSTRIAL APPLICABILITY Processes for purifying recycled polyethylene such as post-consumer and / or postindustrial recycled polyethylene.

Claims

CLAIMS1. A process for purifying recycled polyethylene, the process comprising: dissolving at least a portion of recycled polyethylene in a solvent to provide a first polyethylene-containing solution; contacting the first polyethylene-containing solution with an adsorption media to obtain a second polyethylene-containing solution; and separating a purified recycled polyethylene from the second polyethylenecontaining solution; wherein the solvent has a boiling point higher than 70°C; and wherein a relative energy difference (RED) between the solvent and the polyethylene in the recycled polyethylene, calculated using Hansen Solubility Parameters, is less than or equal to 0.8.

2. The process according to claim 1, wherein the RED is less than or equal to 0.5.

3. The process according to claim 1, wherein the solvent is cyclohexane, xylenes, or a combination thereof.

4. The process according to claim 1, wherein the solvent is cyclohexane.

5. The process according to claim 1, wherein the solvent is xylenes.

6. The process according to any one of claims 1 to 5, wherein the dissolving step is at a temperature between 90°C and 200°C.

7. The process according to any one of claims 1 to 6, wherein the adsorption media comprises activated alumina, silica, zeolite, aluminosilicates, clay, diatomaceous earth, or combinations thereof.

8. The process according to any one of claims 1 to 6, wherein the adsorption media comprises activated alumina.

9. The process according to claim 8, wherein the activated alumina has an average particle size of less than 1.4 mm.

10. The process according to any one of claims 1 to 6, wherein the adsorption media comprises silica.

11. The process according to any one of claims 1 to 6, wherein the adsorption media comprises attapulgite clay.

12. The process according to claim 11, wherein the attapulgite clay has an average particle size of less than 0.6 mm.

13. The process according to any one of claims 1 to 12, wherein one or more of the dissolving, contacting, and separating are at a pressure between 150 psi and 1600 psi.

14. The process according to any one of claims 1 to 12, wherein one or more of the dissolving, contacting, and separating are at a pressure between 300 psi and 1200 psi.

15. The process according to any one of claims 1 to 12, wherein the dissolving is at a pressure between 300 psi and 1200 psi.

16. The process according to any one of claims I to 15, wherein the separating is by liquidliquid extraction or liquid-solid separation.

17. The process according to any one of claims 1 to 15, wherein the separating comprises contacting the second polyethylene -containing solution with an anti-solvent having an RED greater than 1.1.

18. The process according to any one of claims 1 to 17, further comprising pretreating the recycled polyethylene prior to the dissolving.

19. The process according to claim 18, wherein the pretreating comprises contacting the recycled polyethylene with a supercritical fluid.

20. The process according to claim 19, wherein the supercritical fluid comprises dimethyl ether or carbon dioxide.

21. The process according to claim 19, wherein the supercritical fluid is carbon dioxide.

22. The process according to any one of claims 19 to 21, wherein the supercritical fluid further comprises ethanol.

23. The process according to any one of claims 19 to 21, wherein the supercritical fluid further comprises cyclohexane.

24. The process according to claim 18, wherein the pretreating comprises soaking and / or swelling the recycled polyethylene in a pretreatment solvent.

25. The process according to claim 24, wherein the pretreatment solvent comprises a cycloalkane with a boiling point of 45 to 120°C, an aliphatic alkane with a boiling point of 35 to 100°C, an isoparaffin with a boiling point of 25 to 100°C.

26. The process according to claim 24 or 25, wherein the pretreating further comprises removing the pretreatment solvent after the soaking and / or swelling to provide a soaked recycled polyethylene, and further purifying the soaked recycled polyethylene through solidliquid extraction, liquid-liquid extraction, filtration, or a combination thereof.

27. The process according to any one of claims 1 to 26, further comprising filtering the first polyethylene-containing solution prior to the contacting step.

28. The process of any one of claims 1 to 23, wherein the first polyethylene -containing solution comprises up to 40 wt.% dissolved polyethylene.

29. The process according to any one of claims 1 to 28, wherein the purified recycled polyethylene has a lightness improvement, AL*, of at least 5% over the recycled polyethylene.

30. The process according to claim 29, wherein the lightness improvement, AT*, is at least 30%.

31. The process according to any one of claims 1 to 30, wherein the purified recycled polyethylene has an opacity improvement, AO, of at least 15% over the recycled polyethylene.

32. The process according to claim 31, wherein the opacity improvement is at least 40%.

33. The process according to any one of claims 1 to 32 wherein the purified recycled polyethylene has a colour improvement, AE, of at least 30.

34. A purified recycled polyethylene prepared by the process according to any one of claims 1 to 33.

35. The purified recycled polyethylene of claim 34, comprising: less than 1.5 wt.% ash; less than 240 ppm of antioxidants; and less than 50 ppm of slip agents cis-13-docosenamide, (Z)-docos-13-enamide, and N,N'-(ethane- 1 ,2-diyl)di(octadecanamide) .

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