WO2025170590A1

WO2025170590A1 - Degassing process for purification of post-consumer recyclate

Info

Publication number: WO2025170590A1
Application number: PCT/US2024/015182
Authority: WO
Inventors: Bo Li; Mick C. Hundley; William R. PODBORNY; Hrishikesh R. MUNJ
Original assignee: Equistar Chemicals LP
Current assignee: Equistar Chemicals LP
Priority date: 2024-02-09
Filing date: 2024-02-09
Publication date: 2025-08-14
Anticipated expiration: 2026-08-09

Abstract

A method for recycling plastic waste including steps of (i) melting the polyolefin of the plastic waste at a first processing temperature and a first operating pressure, wherein the plastic waste is made from or containing (a) a polyolefin selected from the group consisting of polyethylene and polypropylene and (b) a contaminant having a boiling point less than or equal to the first processing temperature at or above the first operating pressure, thereby providing a polyolefin-based melt and at least partially volatizing the contaminant; (ii) mixing the polyolefin-based melt under a mixing force at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant; and (iii) venting the volatized contaminant from the polyolefin-based melt at or below the first operating pressure, thereby decreasing the amount of contamination in the polyolefin-based melt and purifying the polyolefin-based melt.

Description

DEGASSING PROCESS FOR PURIFICATION OF POST-CONSUMER RECYCLATE

FIELD OF THE INVENTION

[0001] In general, the present disclosure relates to the field of chemistry. More specifically, the present disclosure relates to post-consumer recyclate. In particular, the present disclosure relates to melt-processing and degassing of post-consumer recyclate, related processes, and products prepared therefrom.

BACKGROUND OF THE INVENTION

[0002] The downside to the demand for polyolefin plastics is an increase in plastic waste. As such, there is considerable interest in developing methods to recycle plastic waste. In addition to reducing the amount of plastic waste, other benefits of recycling plastic waste include reducing carbon footprint, consuming less energy, improving water consumption, and using less raw materials.

[0003] In many instances, before plastic waste is recycled and turned into usable resin, the plastic materials are gathered and sent through a process to produce plastic resin pellets. In some instances, the plastics recycling system is a mechanical recycling system, including the steps of sorting, cleaning, shredding, melting, and remolding.

[0004] In some instances, the resulting plastic resin pellets are made from or containing polyolefins, non-polyolefmic polymers, and other contaminants. In some instances, the non- polyolefinic polymers or the other contaminants are present in an amount that adversely affects the properties of the plastic resin pellets. In some instances, the non-polyolefmic polymers or the other contaminants provide stress points in articles made from or containing the plastic resin pellets.

[0005] In some instances, the non-polyolefmic polymers or other contaminants adversely affect the perceptions of users of products made from or containing the plastic resin pellets. For example and in some instances, the non-polyolefmic polymers or other contaminants affect the sense of smell, the sense of taste, or both. Accordingly, the non-polyolefmic polymers or other contaminants render products made therefrom malodorous or foul-tasting. Also, in some instances, packaging, made from or containing the non-polyolefmic polymers or other contaminants, come in contact with foodstuffs and adversely affect the scent, the taste, or both of those foodstuffs. In some instances, the affected products are personal care products or medical devices. BRIEF SUMMARY OF THE INVENTION

[0006] In a general embodiment, the present disclosure provides a method for recycling plastic waste including the steps of (i) melting the polyolefin of the plastic waste at a first processing temperature and a first operating pressure, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, wherein the recyclate is made from or containing (a) a polyolefin selected from the group consisting of polyethylene and polypropylene and (b) a contaminant having a boiling point less than or equal to the first processing temperature at or above the first operating pressure, thereby providing a polyolefin-based melt and at least partially volatizing the contaminant; (ii) mixing the polyolefin- based melt under a mixing force at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant; and (iii) venting the volatized contaminant from the polyolefin-based melt at or below the first operating pressure, thereby decreasing the amount of contamination in the polyolefin-based melt and purifying the polyolefin-based melt.

[0007] In some embodiments, the present disclosure provides a post-consumer recycled resin prepared from a post-consumer recyclate, wherein the resin is selected from the group consisting of polyethylene and polypropylene. In some embodiments, the polyethylene is a high- density polyethylene.

[0008] In some embodiments, the present disclosure provides a post-industrial recycled resin prepared from a post-industrial recyclate, wherein the resin is selected from the group consisting of polyethylene and polypropylene. In some embodiments, the polyethylene is a high- density polyethylene.

[0009] In some embodiments, the present disclosure provides a polymer composition made from or containing resin selected from the group consisting of a post-consumer recycled resin and a post-industrial recycled resin.

[0010] In some embodiments, the present disclosure provides an article of manufacture made from or containing a resin selected from the group consisting of post-consumer recycled resins and post-industrial recycled resins.

[0011] While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description. As will be apparent, certain embodiments, as disclosed herein, are capable of modifications in various aspects, without departing from the spirit and scope of the claims as presented herein. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. DETAILED DESCRIPTION OF THE INVENTION

[0012] While the provided embodiments will be described more fully hereinafter, these embodiments are provided to satisfy applicable laws and regulations. As such, it will be apparent to those skilled in the art that the embodiments can incorporate changes and modifications without departing from the general scope. This disclosure is intended to include the modifications and alterations in so far as the modifications and alterations come within the scope of the appended claims or the equivalents thereof.

[0013] As used in this specification and the claims, the singular forms “a,” “an,” and “the” include plural referents unless the context dictates otherwise.

[0014] As used in this specification and the claims, the terms “comprising,” “containing,” or “including” refer to the presence of that at least the named compound, element, material, particle, or method step in the composition, the article, or the method, but does not exclude the presence of other compounds, elements, materials, particles, or method steps even if the other such compounds, elements, materials, particles, or method steps have the same function as that which is named, unless expressly excluded in the claims. It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps before or after the combined recited steps or intervening method steps between those steps expressly identified.

[0015] Moreover, it is also to be understood that the lettering of process steps or ingredients is for identifying discrete activities or ingredients and the recited lettering can be arranged in any sequence, unless expressly indicated.

[0016] For the purpose of the present description and of the claims which follow, except where otherwise indicated, numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified by the term “about”. Also, ranges include any combination of the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

[0017] Definitions

[0018] In the present description, the term “additive composition” refers to a composition made from or containing an additive.

[0019] In the present description, the term “atmospheric pressure” refers to 1 atm or 101.3kPa. In the present description, the term “low vacuum” refers to 3 to 100 kPa. In the present description, the term “medium vacuum” refers to 100 mPa to 3 kPa. In the present description, the term “high vacuum” refers to 100 nPa to 100 mPa. [0020] In the present description, the term "a.-olefin’’ or “alpha-olefin” refers to an olefin of formula CH2=CH — R, wherein R is a linear or branched alkyl containing from 1 to 10 carbon atoms. In some embodiments, the a-olefin is selected from the group consisting of propylene, 1- butene, 1 -pentene, 1 -hexene, 1 -octene, and 1 -decene.

[0021] In the present description, the term “contaminant” refers to any chemical substance present in a post-consumer recyclate (PCR), a post-industrial recyclate (PIR), a post-consumer recycled resin (PCR resin), or a post-industrial recycled resin (PIR resin), wherein the PCR, the PIR, the PCR resin, or the PIR resin is made from or containing a selected polymer and the presence of the chemical substance thereby renders the PCR, the PIR, the PCR resin, or the PIR resin compositionally different from the pure, selected polymer. In some embodiments, the contaminant is present in an amount ranging from parts per billion (ppb) to percentages, based upon the total weight of the PCR, the PIR, the PCR resin, or the PIR resin. In some embodiments, a multiplicity of contaminants is present. In some embodiments, the contaminant is selected from the group consisting of acrylonitrile butadiene styrene (ABS), calcium carbonate, coffee grounds, diapers, dirt, fillers, food stuffs, glass, grass, labels, metals (including aluminum), nylon, other inorganics, other polymers, paper, plant stems, polycarbonates, polyethylene terephthalate (PET), processing additives, property-imparting additives, rubbers, and wood.

[0022] In the present description, the term “dX value,” where X is 50 or 90, refers to the measured particle diameter upper limit for particles falling within the bottom 50% or 90% by mass, respectively, of the particle distribution. For example, a d50 value of 0.3 un refers to 50% of the particles in the distribution by mass have a diameter of greater than 0.3 pm and 50% of the particles by mass have a diameter lower than 0.3 pm. The d50 value is also referred to as the median particle size herein.

[0023] In the present description, the term “elastomer” refers to polymer compounds having rubber-like properties and crystallinity in the range of from about 0 percent to about 20 percent.

[0024] In the present description, the term “first” refers to the order in which a particular species is presented and does not necessarily indicate that a “second” species will be presented. For example, “first polymer composition” refers to the first of at least one polymer composition. The term does not reflect priority, importance, or significance in any other way. Similar terms used that can be used herein include “second,” “third,” “fourth,” etc.

[0025] In the present description, the term “homopolymer” refers to polymers derived from a single monomeric unit. To the extent that a homopolymer is derived from more than a single monomeric unit, the incorporation of additional monomeric units has no measurable effect on the polymer’s primary, secondary or tertiary structure or no effect on the polymer’s physical or chemical properties. In other words, there is no measurable difference between a polymer, comprising 100 weight percent of a first monomeric unit, and a copolymer, including more than a single monomeric unit.

[0026] In the present description, the term “International Code Council (ICC) Certification” refers to products certified as using 100% post consumer resins.

[0027] In the present description, the term “interpolymer” refers to a polymer prepared by the polymerization of at least two types of monomers or comonomers. The term “interpolymer” includes copolymers, terpolymers, tetrapolymers, and the like. In some embodiments, the term “copolymer” refers to polymers prepared from two different types of monomers or comonomers. In some embodiments, the term “terpolymer” refers to polymers prepared from three different types of monomers or comonomers. In some embodiments, the term “tetrapolymer” refers to polymers prepared from four different types of monomers or comonomers. In some embodiments, the term “copolymer” is used interchangeably with “interpolymer” and refers to polymers made from three or more different ty pes of monomers or comonomers.

[0028] In the present description, the terms “mixing” or “mixing force” refers to the manipulation of a heterogeneous physical stream for rendering the physical stream more homogeneous, that is, reducing non-uniformity and gradients in the physical stream.

[0029] In the present description, the terms “monomer” and “comonomer” are used interchangeably. The terms refer to any compound with a polymerizable moiety that is added to a reactor to produce a polymer. In those instances wherein a polymer is described as made from or containing one or more monomers, for example, a polymer made from or containing propylene and ethylene, the polymer, of course, is made from or containing units derived from the monomers, for example, — CH2 — CH2 — , and not the monomer itself, for example. CH2=CH2.

[0030] In the present description, the term “PCR” refers interchangeably to Post-Consumer Recycled or Post-Consumer Recyclate. including polymers such as high-density polyethylene (HDPE) and polypropylene (PP), which are recycled and reprocessed into a resin for use in various applications.

[0031] In the present description, the term “PIR” refers interchangeably to Post-Industrial Recycled or Post-Industrial Recyclate.

[0032] In the present description, the term “polymer” refers to a macromolecular compound prepared by polymerizing monomers of the same or different type. The term “polymer” includes homopolymers, copolymers, terpolymers, interpolymers, and so on. [0033] In the present description, the term "polymer composition’⁷ refers to a composition made from or containing a polymer.

[0034] In the present description, the term “polyolefin” is used herein broadly and refers to polymers such as polyethylene, ethylene-alpha olefin copolymers (EAO), polypropylene, polybutene, and ethylene copolymers having at least about 50 percent by weight of ethylene polymerized with a lesser amount of a comonomer such as vinyl acetate, and other polymeric resins within the "olefin" family classification.

[0035] In some instances, polyolefins are made by a variety’ of processes including batch and continuous processes using single, staged, or sequential reactors, slurry, solution, and fluidized bed processes and one or more catalysts including for example, heterogeneous and homogeneous systems and Ziegler, Phillips, metallocene, single-site, and constrained geometry catalysts to produce polymers having different combinations of properties.

[0036] In the present description, the term “post consumer recycled (PCR) resin” refers to the recycled product of waste created by consumers, including high-density’ polyethylene postconsumer recycled resin (HDPE PCR) and polypropylene post-consumer recycled resin (PP PCR). Among other forms, PCR resins may take the form of granules, pellets, and powders.

[0037] In the present description, the term “post industrial recycled (PIR) resin” refers to the recycled product of waste generated by manufacturers during the preparation of polymer-based products. In the present description, the disclosed, recycling processes for preparing and using PCR resins are extendable to PIR resins.

[0038] In the present description, the term “recycle” refers to the conversion of waste into a reusable material. The waste is created by consumers, in the case of post-consumer waste, or by manufacturers during the preparation of polymer-based products, in the case of post-industrial waste.

[0039] In the present description, the term “room temperature” refers to a temperature of about 25 degrees Celsius.

[0040] In the present description, the term “shearing force” refers to the application of a cross-sectional, frictional force on the structural integrity' of a polymer composition. In some instances, a shearing force is accompanied with shear heating.

[0041] In the present description, the term “thermoplastic polymer” refers to a polymer that softens when exposed to heat and returns to its original condition when cooled to room temperature. [0042] In the present description, the term “vacuum⁷’ refers to a pressure less than atmospheric pressure.

[0043] In the present description, the term “virgin polymers” refers to polymers prepared in polymerization processes from monomers, with or without catalysts or processing aids, and which are yet to be manufactured into first-use consumer or industrial products.

[0044] In a general embodiment, the present disclosure provides a method for recycling plastic waste including the steps of (i) melting the polyolefin of the plastic waste at a first processing temperature and a first operating pressure, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, wherein the recyclate is made from or containing (a) a polyolefin selected from the group consisting of polyethylene and polypropylene and (b) a contaminant having a boiling point less than or equal to the first processing temperature at or above the first operating pressure, thereby providing a polyolefin-based melt and at least partially volatizing the contaminant; (li) mixing the polyolefin- based melt under a mixing force at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant; and (iii) venting the volatized contaminant from the polyolefin-based melt at or below the first operating pressure, thereby decreasing the amount of contamination in the polyolefin-based melt and purifying the polyolefin-based melt.

[0045] In some embodiments, the mixing force is combined with a shearing force, thereby increasing the disruption of the intermolecular interactions and further facilitating the volatization of the contaminant. In some embodiments, the mixing/shearing force is achieved using an apparatus selected from the group consisting of twin-screw extruders, packed beds, fluidized beds, extraction vessels with one or more trays, and solid-liquid extraction systems. In some embodiments, the mixing/shearing force is achieved using a twin-screw extruder.

[0046] In some embodiments, the decrease in the amount of contamination in the polyolefin-based melt depends upon the length of the twin-screw extruder, that is, the residence time. In some embodiments, the decrease in the amount of contamination in the polyolefin-based melt depends upon the residence time in the shearing/mixing apparatus.

[0047] In some embodiments, the steps are repeated more than one time, thereby further decreasing the amount of contamination. In some embodiments, steps are independently repeated. In some embodiments, the process is continuous or batchwise.

[0048] In some embodiments, the first and second processing temperatures are the same or different. In some embodiments, the second processing temperature is greater than or equal to the first processing temperature. In some embodiments, the first processing temperature is the melting temperature of the polyolefin. In some embodiments, the first processing temperature is greater than or equal to the melting temperature of the polyolefin. In some embodiments, the second processing temperature is greater than the first processing temperature, alternatively greater than the first processing temperature and less than the crosslinking temperature of the polyolefin.

[0049] In some embodiments, the venting step occurs under atmospheric pressure or a vacuum. In some embodiments, the venting step occurs under a high vacuum.

[0050] In some embodiments, the melting step is preceded by a purging step, wherein the plastic waste is subjected to an inert atmosphere and the contaminant is at least partially removed. In some embodiments, the melting step is preceded by a purging step, wherein the plastic waste is subjected to forced air and the contaminant is at least partially removed. In some embodiments, the air is heated or dried.

[0051] In some embodiments, a stripping agent is admixed to the plastic waste. In some embodiments, the stripping agent is inorganic or organic. In some embodiments, the stripping agent is an inorganic selected from the group consisting of water and steam. In some embodiments, the stripping agent is an organic selected from the group consisting of acetone, butane, ethanol, ethyl acetate, hexane, methanol, and mineral oil. In some embodiments, the stripping agents are purged or vented with the volatized contaminant. In some embodiments, the stripping agent entrains the contaminant. In some embodiment, the stripping agent is preheated.

[0052] In some embodiments, a trapping agent is admixed to the plastic waste. In some embodiments, the trapping agent becomes impregnated with or adsorbs the contaminant, thereby rendering the contaminant separable from the polyolefin. In some embodiments, the trapping agent is selected from the group consisting of activated carbon, cyclodextrin compounds, graphene, and zeolite spheres. In some embodiments, the affected contaminant is separated from the polyolefin by particle size, filtering, or other mechanical methods.

[0053] In some embodiments, the plastic waste is characterized to determine the level of contamination. In some embodiments, the polyolefin-based melt is characterized to determine the decrease in the amount of contamination. In some embodiments, the characterization is achieved by gas chromatography -mass spectrometry', liquid chromatography -mass spectrometry, or a total volatiles test. In some embodiments, the amount of contamination is reduced by 50 percent byweight, alternatively 75 percent by weight, alternatively 90 percent by weight, alternatively 99 percent by weight.

[0054] In some embodiments, the method for recycling plastic waste includes the steps of: (a) collecting the plastic waste from residential, commercial, and industrial sites, wherein the plastic waste is selected from the group consisting of postconsumer recyclate and post-industrial recyclate, and made from or containing a polyolefin and a contaminant;

(b) melting the polyolefin at a first processing temperature and a first operating pressure, wherein the contaminant has a boiling point less than or equal to the first processing temperature at or above the first operating pressure, thereby providing a polyolefin-based melt and at least partially volatizing the contaminant;

(c) mixing the polyolefin-based melt under a mixing force at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant;

(d) venting the volatized contaminant from the polyolefin-based melt at or below the first operating pressure, thereby decreasing the amount of contamination in the polyolefin-based melt and purifying the polyolefin-based melt; and

(e) pelletizing the polyolefin-based melt, thereby forming a pelletized resin selected from the group consisting of a pelletized, post-consumer recycled (PCR) resin and a pelletized, post-industrial recycled (PIR) resin.

[0055] In some embodiments, the mixing force is combined with a shearing force, thereby increasing the disruption of the intermolecular interactions and further facilitating the volatization of the contaminant.

[0056] In some embodiments, the method for recycling plastic waste includes the steps of:

(a) collecting the plastic waste from residential, commercial, and industrial sites, wherein the plastic waste is selected from the group consisting of postconsumer recyclate and post-industrial recyclate, and made from or containing a polyolefin and a contaminant;

(c) mixing and shearing the polyolefin-based melt under a combination of mixing and shearing forces at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant;

[0057] In some embodiments, the method for recycling plastic waste further includes the steps of:

(a.i) sorting the plastic waste; and

(a.ii) cleaning the plastic waste.

[0058] In some embodiments, the method for recycling plastic waste further includes the steps of

(b.i) sieving the plastic waste;

(b.ii) separating the plastic waste by particle size; and

(b.iii) collecting the plastic waste in the form of granules or powders.

[0059] In some embodiments, the venting step occurs under atmospheric pressure or a vacuum. In some embodiments, the venting step occurs under a high vacuum.

[0060] In some embodiments, the method for recycling plastic waste includes the steps of:

(a.i) sorting the plastic waste;

(a.ii) cleaning the plastic waste;

(b) melting the polyolefin at a first processing temperature and a first operating pressure, wherein the contaminant has a boiling point less than or equal to the first processing temperature at or above the first operating pressure, thereby providing a polyolefin-based melt and at least partially volatizing the contaminant; (c) mixing and shearing the polyolefin-based melt under a combination of mixing and shearing forces at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant;

(d) venting the volatized contaminant from the polyolefin-based melt under a high vacuum, thereby decreasing the amount of contamination in the polyolefin- based melt and purifying the polyolefin-based melt; and

[0061] In some embodiments, the method for recycling plastic waste include one or more cleaning steps. As previously noted, the mention of one or more method steps does not preclude the presence of additional method steps before or after the combined recited steps or intervening method steps between those steps expressly identified.

[0062] In some embodiments, the plastic waste is made from or containing automobile parts, bleach bottles, food containers, freezer and shopping bags, milk jugs, outdoor furniture, packaging materials, piping, plastic bottles, playground equipment, shampoo bottles, signage and fixtures, toys, and contaminants. In some embodiments, the contaminants are selected from the group consisting of acrylonitrile butadiene styrene (ABS), calcium carbonate, coffee grounds, diapers, dirt, fillers, food stuffs, glass, grass, labels, metals (including aluminum), nylon, other inorganics, other polymers, paper, plant stems, polycarbonates, polyethylene terephthalate (PET), processing additives, property-imparting additives, rubbers, and wood.

[0063] In some embodiments, the present disclosure provides a post-consumer recycled resin prepared from a post-consumer recyclate, wherein the resin is selected from the group consisting of polyethylene and polypropylene. In some embodiments, the polyethylene is a high- density polyethylene.

[0064] In some embodiments, the present disclosure provides a post-industrial recycled resin prepared from a post-industrial recyclate, wherein the resin is selected from the group consisting of polyethylene and polypropylene.

[0065] In some embodiments, the present disclosure provides a polymer composition made from or containing resin selected from the group consisting of a post-consumer recycled resin and a post-industrial recycled resin. In some embodiments, the polymer composition is made from or containing: (a) from 5 % by weight to 95 % by weight, based upon the total weight of the polymer composition, of a resin selected from the group consisting of a post-consumer recycled resin and a post-industrial recycled resin; and

(b) from 5 % by weight to 95 % by weight, based upon the total weight of the polymer composition, of a virgin polymer.

[0066] In some embodiments, the resin is selected from the group consisting of HDPE PCR and PP PCR. In some embodiments, the resin is the base resin of the polymer composition. In some embodiments, the resin is a complementary resin. In some embodiments, the resin is a component in an additive composition or a filler, for use with a virgin or other PCR resin. In some embodiments, the resin is used as a filler in amount alternatively up to 95 % by weight, alternatively up to 90 % by weight, alternatively up to 80 % by weight, alternatively up to 70 % by weight, alternatively up to 60 % by weight, alternatively up to 50 % by weight, alternatively from 0.5 % by weight to 30 % by weight, alternatively from 1.0 % by weight to 20% by weight, based upon the total weight of the polymer composition.

[0067] In some embodiments, the resin bears the International Code Council (ICC) Certification.

[0068] In some embodiments, the resin bears Food and Drug Administration approval for an application selected from the group consisting of food packaging, personal care products, and medical devices.

[0069] In some embodiments, the polymer composition is further made from or containing an additive composition. In some embodiments, the additive composition imparts properties such as thermal stability, light and ultraviolet protection, and color. In some embodiments, the additive composition is present in an amount from 0.05 % by weight to 10 % by weight, alternatively from 0.1 % by weight to 8 % by weight, based upon the total weight of the polymer composition.

[0070] In some embodiments, the present disclosure provides an article of manufacture made from or containing a resin selected from the group consisting of post-consumer recycled resins and post-industrial recycled resins. In some embodiments, the article of manufacture is selected from the group consisting of blow-molded articles, films, flexibles, injection-molded articles, packaging, and piping. In some embodiments, the article of manufacture is useful in noncosmetic-intensive, post consumer recycled resin applications, including agricultural film and trash bags.

Claims

CLAIMS What is claimed is:

1. A method for recycling plastic waste comprising the steps of:

(i) melting the polyolefin of the plastic waste at a first processing temperature and a first operating pressure, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, wherein the recyclate is made from or containing (a) a polyolefin selected from the group consisting of polyethylene and polypropylene and (b) a contaminant having a boiling point less than or equal to the first processing temperature at or above the first operating pressure, thereby providing a polyolefin-based melt and at least partially volatizing the contaminant;

(ii) mixing the polyolefin-based melt under a mixing force at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant; and

(iii) venting the volatized contaminant from the polyolefin-based melt at or below the first operating pressure, thereby decreasing the amount of contamination in the polyolefin- based melt and purifying the polyolefin-based melt.

2. The method for recycling plastic waste of Claim 1, comprising the steps of:

(a) collecting the plastic waste from residential, commercial, and industrial sites, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, and made from or containing a polyolefin and a contaminant;

(c) mixing the polyolefin-based melt under a mixing force at a second processing temperature, thereby decreasing intermolecular interactions between the polyolefin and the contaminant, and further volatizing the contaminant:

(d) venting the volatized contaminant from the polyolefin-based melt, thereby decreasing the amount of contamination in the polyolefin-based melt and purifying the polyolefin-based melt; and (e) pelletizing the polyolefin-based melt, thereby forming a pelletized resin selected from the group consisting of a pelletized, post-consumer recycled (PCR) resin and a pelletized, post-industrial recycled (PIR) resin.

3. The method for recycling plastic waste of Claim 1, comprising the steps of:

(d) venting the volatized contaminant from the polyolefin-based melt at or below the first operating pressure, thereby decreasing the amount of contamination in the polyolefin- based melt and purifying the polyolefin-based melt; and

4. The method for recycling plastic waste of Claim 3, wherein the venting step (d) occurs under a high vacuum.

5. The method for recycling plastic waste of Claim 3, wherein (i) the first processing temperature is greater than or equal to the melting temperature of the polyolefin and (ii) the second processing temperature is greater than the first processing temperature and less than the crosslinking temperature of the polyolefin.

6. The method for recycling plastic waste of Claim 5, wherein the venting step (d) occurs under a high vacuum.

7. The method for recycling plastic waste of Claim 1, wherein the plastic waste comprises automobile parts, bleach bottles, food containers, freezer and shopping bags, milk jugs, outdoor furniture, packaging materials, piping, plastic bottles, playground equipment, shampoo bottles, signage and fixtures, toys, and contaminants.

8. The method for recycling plastic waste of Claim 3, wherein the contaminants are selected from the group consisting of acrylonitrile butadiene styrene (ABS), calcium carbonate, coffee grounds, diapers, dirt, fillers, food stuffs, glass, grass, labels, metals (including aluminum), nylon, other inorganics, other polymers, paper, plant stems, polycarbonates, polyethylene terephthalate (PET), processing additives, property-imparting additives, rubbers, and wood.

9. A post-consumer recycled resin comprising (a) 50 to 100 weight by percent of a resin selected from the group consisting of polyethylene and polypropylene and (b) 0 to less than 50 weight by percent of contaminants, having a boiling point less than or equal to the melting point of the resin, based upon the total weight of the post-consumer recycled resin.

10. An article of manufacture comprising the post-consumer recycled resin of Claim 9.