Microfluidic purification of post-consumer recyclate

Abstract

A method for recycling plastic waste including the steps of (i) grinding plastic waste into particles; (ii) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid; (iii) injecting the suspension into a microfluidic system, alternatively coupled with an acoustophoresis system; (iv) compressing the particles; and (v) separating the particles.

Description

MICROFLUIDIC PURIFICATION OF POST-CONSUMER RECYCLATEFIELD 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 microfluidic purification 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-polyolefinic 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-polyolefinic polymers or the other contaminants provide stress points in articles made from or containing the plastic resin pellets.BRIEF SUMMARY OF THE INVENTION

[0005] In a general embodiment, the present disclosure provides a method for recycling plastic waste including the steps of (i) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles (a) having dimensions smaller than 1000 microns, (b) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles, (c) having a composition-dependent bulkmodulus, and (d) having a composition-dependent density; (ii) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid; (iii) injecting the suspension into a microfluidic system, having ridged microchannels; (iv) compressing the particles with the ridges via the flow rate, the viscosity, or both of the fluid; and (v) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin. In some embodiments, the microfluidic system is coupled with an acoustophoresis system, wherein the method further include the steps of (vi) generating sound energy, thereby creating pressure nodes or antinodes; and (vii) in response to acoustic contrast factors, compressing the particles.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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

[0011] 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.

[0012] As used in this specification and the claims, the singular forms “a,” “an,” and “the” include plural referents unless the context dictates otherwise.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] Definitions

[0017] In the present description, the term “acoustic wave” refers to a type of mechanical wave that propagates along a longitudinal wave driven by an acoustic source, generated by the mechanical stress from a piezoelectric transducer. Acoustic waves are categorized as surfaceacoustic waves or bulk acoustic waves. There are two types of surface-acoustic-waves-driven microfluidics: (i) traveling and (ii) standing.

[0018] In the present description, the term “acoustophoresis” refers to the displacement of suspended objects in response to directional forces from sound energy. In some embodiments, the sound energy is generated from a piezoelectric transducer pulsating at frequencies in the megahertz range. The sound energy focuses particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the waves, respectively. The acoustic contrast is calculable from the particle's density and compressibility, and from the density and compressibility of the suspending fluid.

[0019] In some embodiments, the waves are selected from the group consisting of bulk acoustic standing waves, surface acoustic standing waves, and acoustic traveling waves. In some embodiments, devices supporting bulk acoustic standing waves rearrange particles based on the mechanical vibrations of the walls of the device generated by a piezoelectric transducer, which excites the standing waves in microfluidic cavities at geometrically-defined resonant frequencies, thereby enabling higher pressure amplitudes compared to surface-acoustic-standing-wave devices.

[0020] In some emodiments, the acoustic parameters of amplitude, frequency, and phase of sound waves are continuously or intermittently maintained or modified.

[0021] In the present description, the term “additive composition” refers to a composition made from or containing an additive.

[0022] 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.

[0023] In the present description, the term “bulk acoustic wave” refers to a standing wave that propagates inside the resonant chamber of a microchannel. In bulk-acoustic-wave-based microfluidic devices, the piezoelectric transducer is bonded on the microchannels. Unlike surface acoustic waves, which spread along the surface of the material, bulk acoustic waves propagate inside the bulk of the material. In some embodiments and compared with surface-acoustic-wave- based separation devices, bulk-acoustic-wave-based devices work at a lower frequency and a longer wavelength, thereby allowing for larger particles.

[0024] In the present description, the term “bulk modulus” or “incompressibility” refers to a measure of the ability of a substance to withstand changes in volume when under compression on the substance’s sides and is equal to the quotient of the applied pressure divided by the relative deformation.

[0025] In the present description, the terms “comminute,” “grind,” “mill,” “powder,” “pulverize,” and “triturate” are used interchangeably and refer to dividing or reducing postconsumer polymer-containing waste or post-industrial polymer-containing waste mechanically into particles having dimensions smaller than 1mm (or 1000 microns), alternatively smaller than 100 microns, alternatively smaller than 10 microns, alternatively smaller than 1 micron, alternatively in the range of 10 microns to 1000 microns, alternatively 10 microns to 100 microns.

[0026] 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, fdlers, 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.

[0027] 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 pm 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In the present description, the term “International Code Council (ICC) Certification” refers to products certified as using 100% post consumer resins.

[0032] 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 types of monomers or comonomers.

[0033] In the present disclosure, the term “microchannel” refers to channels with diameters ranging from tens to hundreds of micrometers.

[0034] In the present disclosure, the term “microfluidic” refers to the manipulation of small amounts of fluids through microchannels.

[0035] In some instances, a microfluidic system includes a substrate. A dispersion-phase fluidic microchannel is formed in the substrate. A continuous-phase fluidic microchannel is also formed in the substrate. The dispersion-phase fluidic microchannel and the continuous-phase fluidic microchannel are in fluid communication through an aperture in a microchannel wall therebetween.

[0036] In some instances involving sound energy, an interdigital transducer is in contact with the substrate and generates a surface acoustic wave to inject fluid from the dispersion-phase fluidic microchannel into the continuous-phase fluidic microchannel through the aperture. In some instances, the microfluidic system deflects or diverts selected particles in the dispersion-phase fluidic microchannel to the continuous-phase fluidic microchannel while avoiding disruption to the flow of unselected particles in the dispersion-phase fluidic microchannel.

[0037] In some embodiments, the fluid in the dispersion-phase fluidic microchannel is the same as the fluid in the continuous-phase fluidic microchannel. In some embodiments, the fluid in the dispersion-phase fluidic microchannel differs from the fluid in the continuous-phase fluidic microchannel in one or more characteristics. In some embodiments, the characteristic is selected from the group consisting of aprotic, aromatic, hydroaffinity, nonaromatic, particle solubility, particle swellability, pH, polarity, and viscosity. In some embodiments, the composition of the fluid is modified with surfactants or emulsifiers.

[0038] In the present disclosure, the term “microfluidic separation” refers to the nondestructive separation of particles with a fluid to exploit the variation in bulk moduli between particles made from or containing different compositions. In some embodiments, additional physical properties of the particles affect the separation characteristics. In some embodiments, the physical properties are selected from the group consisting of elastic modulus, particle density, particle size, and porosity.

[0039] In some instances, the microfluidic separation uses microchannels to focus particles in the center of the microchannel and at least two outlets for particles having differing bulk moduli. In some embodiments, a first outlet provides egress for particles from a dispersion-phase fluidic microchannel and a second outlet provides egress for particles from the dispersion-phase fluidic microchannel into the continuous-phase fluidic microchannel.

[0040] In some embodiments, the microchannels have ridges on a first wall, with the gap between the ridges and the opposite second wall smaller than the diameter of the particles. As thefluid streams the particles through the microchannels, the ridges periodically compress the particles. Based upon differing bulk moduli, the compression gives rise to a stiffness-dependent force associated with the particles passages through constrictions formed by consecutive channel ridges. This elastic force is directed normal to the compressive ridges and, therefore, has a component that deflects particles propelled by the flow in the transverse direction with a rate proportional to the particles’ bulk modulus. In addition to the elastic force, particles experience a transverse fluid-dependent force due to circulatory flow created by diagonal ridges. The elastic and tranverse forces act in opposing directions, and the balance between these two forces sets particle trajectories that diverge for particles with different bulk moduli.

[0041] In microfluidic separation, the flow rate and viscosity of the fluid define the transverse fluid-dependent force. When the tranverse fluid-dependent force is coupled with directional forces from sound energy (that is, via acoustophoresis), the particles are subject to increased compression force. In some embodiments, acoustic devices focus particles across a wide range of applied flow rates and independent of the flow direction, which is not possible in devices that rely on inertial forces for focusing, thereby more efficiently transporting particles.

[0042] 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.

[0043] In the present description, the term “PCR” refers interchangeably to Post-ConsumerRecycled 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.

[0044] In the present description, the term “PIR” refers interchangeably to Post-Industrial Recycled or Post-Industrial Recyclate.

[0045] 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.

[0046] In the present description, the term “polymer composition” refers to a composition made from or containing a polymer.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] In the present description, the term “room temperature” refers to a temperature of about 25 degrees Celsius.

[0053] In the present description, the term “standing surface acoustic wave” refers to a surface acoustic wave that is generated by two opposite traveling surface acoustic waves interfering or a reflecting traveling surface acoustic wave, creating fixed nodes and antinodes in an open or confined domain.

[0054] 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.

[0055] In the present description, the term ‘traveling surface acoustic wave” refers to a surface acoustic wave that propagates in one direction and radiates away from the acoustic source.

[0056] 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.

[0057] Testing

[0058] ASTM D 792 is entitled “Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement.” The term “ASTM D 792” as used herein refers to the standard test method for determining the specific gravity (relative density) and density of solid plastics in forms such as sheets, rods, tubes, or molded items. The test method includes determining the mass of a specimen of the solid plastic in air, determining the apparent mass of the specimen upon immersion in a liquid, and calculating the specimen’s specific gravity (relative density).

[0059] ASTM D 1505 is entitled “Standard Test Method for Density of Plastics by the Density-Gradient Technique.” The term “ASTM D 1505” as used herein refers to a test method based on observing the level to which a test specimen sinks in a liquid column exhibiting a density gradient, in comparison with standards.

[0060] For the referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org.

[0061] In a general embodiment, the present disclosure provides a method for recycling plastic waste including the steps of (i) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles (a) having dimensions smaller than 1000 microns, (b) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles, (c) having a composition-dependent bulk modulus, and (d) having a composition-dependent density; (ii) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid; (iii) injecting the suspension into a microfluidic system, having ridged microchannels; (iv) compressing theparticles with the ridges via the flow rate, the viscosity, or both of the fluid; and (v) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin.

[0062] In some embodiments, the steps are performed as part of a batch method. In some embodiments, the steps are performed as a part of a continuous method. In some embodiments, the steps are performed at room temperature or at an elevated temperature.

[0063] In some embodiments, the flow rate and the viscosity of the fluid are independently controlled or variable.

[0064] In some embodiments, the microfluidic system is coupled with an acoustophoresis system, wherein the method further include the steps of (vi) generating sound energy, thereby creating pressure nodes or antinodes; and (vii) in response to acoustic contrast factors, compressing and separating the particles.

[0065] 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) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles(b.l) having dimensions smaller than 1000 microns,(b.2) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles,(b.3) having a composition-dependent bulk modulus, and(b.4) having a composition-dependent density;(c) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid;(d) injecting the suspension into a microfluidic system, having ridged microchannels;(e) compressing the particles with the ridges via the flow rate, the viscosity, or both of the fluid;(f) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin;(g) extracting the particles from the first suspension;(h) melting the particles, thereby yielding a fusion-melt; and(i) pelletizing the fusion-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.

[0066] In some embodiments, the method for recycling plastic waste further includes the steps of:(e.i) generating sound energy, thereby creating pressure nodes or antinodes; and(e.ii) in response to acoustic contrast factors, compressing the particles.

[0067] 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.

[0068] 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 post-consumer recyclate and post-industrial recyclate, and made from or containing a polyolefin and a contaminant;(b) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles(b.l) having dimensions smaller than 1000 microns,(b.2) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles,(b.3) having a composition-dependent bulk modulus, and(b.4) having a composition-dependent density;(c) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid;(d) injecting the suspension into a microfluidic system, having ridged microchannels;(e) generating sound energy, thereby creating pressure nodes or antinodes;(f) compressing the particles(f l) with the ridges via the flow rate, the viscosity, or both of the fluid and(f 2) in response to acoustic contrast factors;(g) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin;(h) extracting the particles from the first suspension;(i) melting the particles, thereby yielding a fusion-melt; and(j) pelletizing the fusion-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.

[0069] In some embodiments, the method for recycling plastic waste includes a pretreatment selected from the group consisting of acid pretreatment, alkaline pretreatment, other surface-area-increasing treatment, irradiation, organic solvent pretreatment, and ozone.

[0070] 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.

[0071] In some embodiments, the method is operated batchwise or continuously.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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 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.

[0077] In some embodiments, the resin bears the International Code Council (ICC) Certification.

[0078] 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.

[0079] 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

CLAIMSWhat is claimed is:

1. A method for recycling plastic waste comprising the steps of:(i) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles(a) having dimensions smaller than 1000 microns,(b) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles,(c) having a composition-dependent bulk modulus, and(d) having a composition-dependent density;(ii) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid;(iii) injecting the suspension into a microfluidic system, having ridged microchannels;(iv) compressing the particles with the ridges via the flow rate, the viscosity, or both of the fluid; and(v) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin.

2. The method for recycling plastic waste of Claim 1, further comprising the steps of:(vi) generating sound energy, thereby creating pressure nodes or antinodes; and(vii) in response to acoustic contrast factors, compressing and separating the particles.

3. 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 comprising the polyolefin and the contaminant;(b) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles(b.l) having dimensions smaller than 1000 microns,(b.2) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles,(b.3) having a composition-dependent bulk modulus, and(b.4) having a composition-dependent density;(c) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid;(d) injecting the suspension into a microfluidic system, having ridged microchannels;(e) compressing the particles with the ridges via the flow rate, the viscosity, or both of the fluid;(f) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin;(g) extracting the particles from the first suspension;(h) melting the particles, thereby yielding a fusion-melt; and(i) pelletizing the fusion-melt, thereby forming a pelletized resin selected from the group consisting of a pelletized, post-consumer recycled (PCR) resin and a pelletized, postindustrial recycled (PIR) resin.

4. The method for recycling plastic waste of Claim 3, wherein the dimensions are smaller than 100 microns.

5. 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 recy elate and post-industrial recyclate, and comprising the polyolefin and the contaminant;(b) grinding plastic waste, wherein the plastic waste is selected from the group consisting of post-consumer recyclate and post-industrial recyclate, thereby providing particles(b.l) having dimensions smaller than 1000 microns,(b.2) independently made from or containing from 0 to 100 weight percent of a polyolefin and 0 to 100 weight percent of a contaminant, based upon the total weight of the particles,(b.3) having a composition-dependent bulk modulus, and(b.4) having a composition-dependent density;(c) suspending the particles in a liquid, thereby providing a suspension made from or containing the particles and a fluid;(d) injecting the suspension into a microfluidic system, having ridged microchannels;(e) generating sound energy, thereby creating pressure nodes or antinodes;(f) compressing the particles(f l) with the ridges via the flow rate, the viscosity, or both of the fluid and(f.2) in response to acoustic contrast factors;(g) in response to the compression forces, separating the particles between a dispersion-phase fluidic microchannel and a continuous-phase fluidic microchannel and yielding a first suspension made from or containing particles made from or containing 50 weight percent or more of a polyolefin and a second suspension made from or containing particles made from or containing less than 50 weight percent of a polyolefin;(h) extracting the particles from the first suspension;(i) melting the particles, thereby yielding a fusion-melt; and(j) pelletizing the fusion -melt, thereby forming a pelletized resin selected from the group consisting of a pelletized, post-consumer recycled (PCR) resin and a pelletized, postindustrial recycled (PIR) resin.

6. The method for recycling plastic waste of Claim 5, wherein the dimensions are smaller than 100 microns.

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 7, 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 percent of a resin selected from the group consisting of polyethylene and polypropylene and (b) 0 to less than 50 weight percent of contaminants, 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.