Polymer recycling process

Abstract

A method for identifying polymers through their life cycle is provided. The method comprises tagging one or more polymers with unique tags to produce one or more tagged polymers. The method may further comprise identifying the tagged polymers in a mixed plastic waste stream using means for detecting the tags, separating the one or more tagged polymers from a mixed plastic waste stream in response to detecting the one or more tags, and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers comprising the same tag.

Description

POLYMER RECYCLING PROCESSFIELD OF THE INVENTION

[0001] The present disclosure relates to polymer products and methods for producing such products by blending a polymer recyclate and a compatibilizer, wherein the polymer recyclate comprises a polyolefin component and a polyamide component.BACKGROUND OF THE INVENTION

[0002] Polyolefins, in particular polyethylene and polypropylene, are increasingly consumed in large amounts for many applications, including packaging for food and other goods, electronics, automotive components, and a great variety of manufactured articles. Large amounts of waste plastic materials are presently coming from differential recovery of municipal plastic wastes, mainly constituted of flexible packaging (cast film, blown film and BOPP film), rigid packaging, blow molded bottles and injection molded containers. Usually, recovery of polymer recyclate includes a step of separation of various types of polymers prior to further processing.

[0003] Discarded plastic articles that are collected in municipal recycling programs must be sorted and separated by plastic type, since many types of plastics are incompatible. For instance, polyethylene and polypropylene are incompatible, and blends of same have inferior mechanical and / or optical properties. Further, even with separation of incompatible polymers, such as polyethylene or polypropylene, into separate portions, some articles (e.g., multilayer barrier films) within these sorted portions frequently significant levels of contamination from other incompatible plastics, such as, but not limited to nylon (polyamide), which are incompatible with both polyethylene and polypropylene and can cause significant deterioration of the mechanical properties of polyethylene and / or polypropylene when present at modest levels.

[0004] There is a need to improve the processability of polymer recyclates and to produce compositions comprising such recycled materials having a useful combination of properties that are competitive with virgin polymer compositions. An important step toward these goals is improving the separation of bulk waste plastics containing articles comprising different polymers into separate portions of articles having a reduced variation of polymer compositions. Ideally, such processes would be highly flexible and could be implemented with commonly used equipment and familiar techniques to produce a wide variety of products.SUMMARY OF THE INVENTION

[0005] The present disclosure relates to a method for identifying polymers through their life cycle spanning from production through recovery in a recycling process. The method comprises providing one or more unique tags corresponding to each of one or more different polymers, respectively, and adding each of the unique tags to each of the corresponding polymers to produce one or more tagged polymers.

[0006] In some embodiments, the method further comprises identifying each tag using means for detecting the one or more tags. The amount of each of the unique tags added to each of the corresponding polymers, respectively, is in the range of from an amount sufficient to be detected by the means for detecting the tags to an amount insufficient to cause an undesirable change in performance between each of the polymers and each of the corresponding tagged polymers, respectively.

[0007] In some embodiments, the method further comprises separating each of the one or more tagged polymers from the plastic waste stream in response to identifying the one or more tagged polymers and forming one or more collections of discrete portions of each of the one or more tagged polymers, wherein each collection consists substantially of portions of tagged polymers having the same tag.

[0008] In some embodiments, the tags comprise color agents, additives have a light emissions signature, functional groups, or a combination thereof.

[0009] The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter, which form the subject matter of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, together with further objects and advantages will be better understood from the following description.DETAILED DESCRIPTION OF THE INVENTION

[0010] Illustrative embodiments of the subject matter claimed below will now be disclosed. In the interest of clarity, some features of some actual implementations may not be described in this specification. It will be appreciated that in the development of any such actual embodiments, numerous implementation-specific decisions must be made to achieve the developer’s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0011] The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than the broadest meaning understood by skilled artisans, such a special or clarifying definition will be expressly set forth in the specification in a definitional manner that provides the special or clarifying definition for the term or phrase. It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless otherwise specified.

[0012] For example, the following discussion contains a non-exhaustive list of definitions of several specific terms used in this disclosure (other terms may be defined or clarified in a definitional manner elsewhere herein). These definitions are intended to clarify the meanings of the terms used herein. It is believed that the terms are used in a manner consistent with their ordinary meaning, but the definitions are nonetheless specified here for clarity.Definitions

[0013] As used herein, “color” means the appearance of an object or material in the visual spectrum including all colors— e.g., white, grey, black, red, violet, amber, almond, orange, aquamarine, tan, forest green, etc., primary colors, secondary colors, and all variations between.

[0014] As used herein, “color agent” means and additive that imparts color to a polymer, such as, but not limited to, pigments, dyes, or a combination thereof. In some embodiments, a color agent is florescent. In some embodiments, although color is in the visual spectrum, theconcentration of the color agent may be so low the color is not detectable by the human eye without some type of enhance via an electro mechanical device.

[0015] As used herein, “colorimeter” focuses on measuring color perception in a standardized manner.

[0016] As used herein, “colorimeter” refers a device used to measure the color of an object or substance based on the perception of human vision. It quantifies the color by measuring the intensity of light across specific color channels, typically red, green, and blue (RGB) and provides color information in terms of standardized color spaces like CIE XYZ, LAB, or LCH. Exemplary devices are disclosed in U.S. Pat. Nos. 6,272,440, 3,003,388, and 8,031,938.

[0017] As used herein, “compatibility” means the capability of the individual component substances in an immiscible polymer blend to exhibit interfacial adhesion, in which interfaces between phases or components are maintained by intermolecular forces, chain entanglements, or both, across the interfaces — i.e., holding together of two bodies by interfacial forces or mechanical interlocking on a scale of micrometers or less. Further discussion of miscibility can be found in D. W. Fox and R. B. Allen, ‘Compatibility’, Encyclopedia of Polymer Science and Engineering, 2nd Ed., J. I. Kroschwitz, ed., Wiley Interscience, New York, 1985, Vol. 3, p. 784. Work, W. J., Hone, K., Hess, M., & UK, R. S. (2004), Definitions of Terms Related to Polymer Blends, Composites and Multiphase Polymeric Materials, Pure and Applied Chemisiry76. 11, the substance of which is fully incorporated herein by reference.

[0018] As used herein, “compounding conditions” means temperature, pressure, and shear force conditions implemented in an extruder to provide intimate mixing of two or more polymers and optionally additives to produce a substantially homogeneous polymer product. The compounding conditions will be such that the specific energy from the compounder from shear and / or added heat are sufficient to melt the polymer components and homogenize them.

[0019] As used herein, “fluorescence” refers to the ability of certain chemicals to give off visible light after absorbing shorter wavelength radiation which is not normally visible, such as as X-rays or ultraviolet light.

[0020] As used herein, “HDPE” means ethylene homopolymers and ethylene copolymers produced in a suspension, solution, slurry, or gas phase polymerization process and having a density in the range of 0.940 g / cm3to 0.970 g / cm3.

[0021] As used herein, “LDPE” means ethylene homopolymers and / or ethylene copolymers produced in a high pressure free radical polymerization and having a density in the range of 0.910 g / cm3to 0.940 g / cm3.

[0022] As used herein, “LLDPE” means ethylene copolymers produced in a suspension, solution, slurry, or gas phase polymerization process and having a density in the range of 0.910 g / cm3to 0.940 g / cm3.

[0023] As used herein, “MDPE” means ethylene copolymers produced in a suspension, solution, slurry, or gas phase polymerization process and having a density in the range of 0.925 g / cm3to 0.940 g / cm3.

[0024] As used herein, “miscibility” means the degree to which two polymers will mix to form homogeneous polymer blends. Miscibility is the capability of a mixture to form a single phase over certain ranges of temperature, pressure, and composition. Whether or not a single phase exists depends on the chemical structure, molar mass distribution, and molecular architecture of the components present. A single phase in a mixture may be confirmed by light scattering, x-ray scattering, and / or neutron scattering. For a two-component mixture, a necessary and sufficient condition for stable or metastable equilibrium of a homogeneous, single-phase is:wherein AmixG is the Gibbs energy of mixing per unit volume, and the composition, where is usually taken as the volume fraction of one of the component substances. The system is unstable if the above second derivative is negative. The borderline (spinodal) between (meta)stable and unstable states is defined by the above second derivative equaling zero. Further discussion of miscibility can be found in J.M.G. Cowie, ‘Miscibility’, Encyclopedia of Polymer Science and Engineering, 2nd Ed., J. I. Kroschwitz, ed., Wiley Interscience, New York, 1985, Supplement, p. 455-480, and Work, W. J., Horie, K., Hess, M., & UK, R. S. (2004), Definitions of Terms Related io Polymer Blends, Composites and Multiphase Polymeric Materials, Pure and Applied. Chemistry? 6 / 11, the substance of which is fully incorporated herein by reference.

[0025] As used herein, “mixed plastic waste” means a mixture and discrete portions of polymer waste wherein at least two of the discrete portions are different polymers.

[0026] As used herein, “near-IR” means a portion of the infrared light spectrum adjacent to the visible light spectrum. Near-IR is the light wavelength range of from about 700 nm to 1,500 nm.

[0027] As used herein, “photometer” refers to an instrument for measuring the intensity of light.

[0028] As used herein, “polar monomer,” as used herein, means monomers containing highly electronegative atoms, such as chlorine, fluorine, oxygen, nitrogen, or sulfur, that give rise to polymers that contain permanent electric dipoles.

[0029] As used herein, “polar polymer” means a polymer or copolymer comprising units derived from a polar monomer. The term "polar polymer," as used herein, refers to polymer formed from at least one monomer that comprises at least one heteroatom. Some examples of heteroatoms include O, N, P and S.

[0030] As used herein, “polymer recyclate” means post-consumer recycled (“PCR”) polymer and / or post-industrial recycled (“PIR”) polymer. Polymer recyclate is derived from an end product that has completed its life cycle as a consumer item and would otherwise be disposed of as waste (e g., a polyethylene water bottle) or from plastic scrap that is generated as waste from an industrial process. Polymer recyclates herein are a mixture of a polyolefin component and a polyamide component.

[0031] As used herein, “polymer” means any thermoplastic polymer suitable for recycling.

[0032] As used herein, “polyolefin” in some embodiments is a type of polymer with the general formula (CILCHRjn where R is an alkyl group, including, but not limited to LDPE, LLDPE, MDPE, HDPE, and PP. Polyolefins are nonpolar polymers.

[0033] As used herein, “ppmw” means parts per million by weight.

[0034] As used herein, “processability” refers to how well a polymer composition can be formed into a cast or blown film of commercial quality or molded by injection, compression, or blow molding into a molded article of commercial quality at commercially acceptable rates using the equipment and conditions.

[0035] As used herein, “spectrometer” refers to an instrument that measures the intensity of light across a broad range of wavelengths, typically from ultraviolet (UV) to near-infrared (NIR) regions. It provides detailed spectral information about the light, allowing the identification and quantification of specific wavelengths. Spectrometers can be used to analyze the composition,concentration, and optical properties of materials. Spectrophotometers can provide data in terms of absorbance, transmittance, or reflectance, and they are often used to determine the concentration of substances in a sample.

[0036] As used herein, “spectrophotometer” refers to a device that measures color differences high-precision analysis and accurate color management. Exemplary devices are disclosed in U.S. Pat. Pub. 2007 / 0059844.

[0037] As used herein, “spectroradiometer” refers to a specialized spectrometer that measures the spectral power distribution (SPD) of light, including its radiant flux at different wavelengths. It provides information about the absolute or relative amount of light energy emitted, transmitted, or reflected by a light source or material. Spectroradiometers are used for applications such as characterizing light sources, evaluating display technologies, and measuring the spectral properties of surfaces.

[0038] As used herein, “tag” refers to a substance added to a polymer to provide a unique identifier or signature for that polymer. After that polymer has been formed into an article (e.g., container, film, bubble wrap, etc.) and passed through the stream of commerce to be recovered as plastic waste, the tag can be used to distinguish articles comprising that polymer from articles comprising other polymers.

[0039] As used herein, “UV” means ultraviolet light, which is adjacent to the visible light spectrum and has the light wavelength range of from about 100 nm to 400 nm.

[0040] As used herein, “visual spectrum” means the light wavelength range detectable by human observation, wherein specific wavelength within that range are recognized as specific colors. The “visual spectrum” and similar such terms refers to light having a wavelength that is visible, e.g., perceptible, to the human eye, and includes light generally in the wavelength range of about 400 nm to about 800 nm.

[0041] In the present description, the terms “monomer” and “comonomer” are used interchangeably. The terms mean any compound with a polymerizable moiety that is added to a reactor in order to produce a polymer. In those instances in which a polymer is described as comprising one or more monomers, e.g., a polymer comprising propylene and ethylene, the polymer, of course, comprises units derived from the monomers, e.g., — CH2 — CH2 — , and not the monomer itself, e.g., CH2=CH2. For example, when a copolymer is described as having an “ethylene” content of 35 wt.% to 55 wt.%, it is understood that the mer unit in the copolymer isderived from ethylene in the polymerization reaction and the derived units are present at 35 wt.% to 55 wt.%, based upon the weight of the copolymer.

[0042] It is noted that in this disclosure and particularly in the claims and / or paragraphs, terms such as “comprises”, “comprised”, “comprising” and the like can have the meaning attributed to it in U.S. patent law; e.g., they can mean “includes”, “included”, “including”, and the like; and that terms such as “consisting essentially of’ and “consists essentially of’ have the meaning ascribed to them in U.S. patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the disclosure.Polymer production

[0043] The present disclosure relates to a method for identifying polymers through their life cycle spanning from production through recovery in a recycling process. The method comprises providing one or more unique tags corresponding to each of one or more polymers, respectively, and adding each of the unique tags to each of the corresponding polymers to produce one or more tagged polymers.

[0044] In some embodiments, an industry standard could be developed and implemented for tagging thermoplastic polymers during manufacture to provide unique identification of different types of polymers. Such identification of different types of polymers can be an important aspect of recycling polymers. Those skilled in the art understand that mixtures of incompatible polymers can have poor processing characteristics and result in polymer blends that have poor mechanical and / or optical properties due to formation of gels and / or a dispersed phase of domains of one blend component in a matrix phase of the other blend component. In the context of recycling plastic waste, providing an industry-wide system for tagging polymers with unique tags would provide a mechanism for sorting and separating bulk plastic waste into portions comprising similar polymers. Recyclate resins produced from each portion of similar polymers could reduce, minimize, or eliminate the occurrence of PCR resins comprising incompatible polymer blends.

[0045] The unique tag corresponding to each different polymer as defined in the tagging system is added at least in an amount sufficient to permit identification and differentiation of articles comprising each of the different polymers in bulk plastic waste. The maximum amount of the unique tag added to each corresponding different polymer would be insufficient to cause an undesirable change in performance between each of the polymers and each of the tagged polymers. The absolute range of addition of a tag, either on a molar or a weight basis, would vary based onthe particular type of tag and the sensitivity of devices used for detecting that type of tag. In some embodiments, the same type of tag is used for all polymers encompassed by the tagging system. In some embodiments, a different type of tag is used for different polymer types — e.g., a first type of tag for polyethylenes and a second type of tag for polypropylenes would allow a first separation of polyethylenes from polypropylenes based on the type of tag and then a second separation based on individual tags to isolate distinct types of polyethylenes and / or distinct types of polypropylenes. In some embodiments, only certain polymers are included in the tagging system to allow extraction of those certain polymers from bulk plastic waste.

[0046] In some embodiments, the one or more tags comprises one or more color agents suited to impart one or more selected colors corresponding to each of the one or more tagged polymers. In some embodiments, the color agents comprise pigments, dyes, or a combination thereof. In some embodiments, pigments comprise organic pigments, inorganic pigments, carbon black, white pigments, special effect pigments, aluminum pigments, fluorescent pigments, photochromic pigments, thermochromic pigments, or a combination thereof. Additional information regarding pigments can be found at https: / / polymer-additives.specialchem.com / selection-guide / pigments- for-plastics. Dyes spanning the visible and near-IR wavelength ranges are available for use in thermoplastic polymers, including polycarbonate, acrylic, polyamide, polystyrene, polyvinyl chloride, and polyurethane, such as, but not limited to, Epolight™ dyes, available from Epolin, LLC, 358-364 Adams Street, Newark, New Jersey 07105. Additional information regarding pigments can be found at https: / / epolin.com / epolin_product / nir-and-visible-absorbing-dyes- thermoplastics / .

[0047] In some embodiments, each tagged polymer comprises the corresponding color agent in an amount in the range of from 50 ppmw to 20,000 ppmw, from 100 ppmw to 15,000 ppmw, or from 500 ppmw to 10,000 ppmw, based on the weight of each tagged polymer.

[0048] In some embodiments, pigment is added by direct compounding in an extruder or melt mixer, masterbatching, solvent coloring of polymer pellets, or dry mixing pigment with polymer pellets. Such methods are subsets of compounding, as defined herein, as compounding in an extruder or melt mixer is a final step in these addition methods to assure uniform distribution of the pigment.

[0049] In some embodiments, the one or more tags comprise one or more additives suited to impart one or more selected light emission signatures corresponding to each of the one or moretagged polymers. In some embodiments, the additives comprise compositions emitting light at wavelengths in the near-IR range, the visible range, the UV range, or a combination thereof. Such additives include but are not limited to: molecules containing one or more hydroxyl groups, one or more amine groups, one or more carboxyl groups, or a combination thereof, which absorb in the near-IR region (e g., alcohols, glycols, fatty acids, and amines); molecules which contain highly conjugated carbon-carbon double bonds, which absorb in the UV and visible light regions (e.g., 1,3 -butadiene, benzene, and beta-carotene); or a combination thereof.

[0050] In some embodiments, each tagged polymer comprises the corresponding additive in an amount in the range of from 50 ppmw to 20,000 ppmw, from 100 ppmw to 15,000 ppmw, or from 500 ppmw to 10,000 ppmw, based on the weight of each tagged polymer.

[0051] In some embodiments, the additive is added by direct compounding in an extruder or melt mixer, masterbatching, or dry mixing additive with polymer pellets. Such methods are subsets of compounding, as defined herein, as compounding in an extruder or melt mixer is a final step in these addition methods to assure uniform distribution of the additive.

[0052] In some embodiments, the one or more tags comprise one or more functional groups, wherein each functional group has a distinct near-IR signature corresponding to each of the one or more tagged polymers. In some embodiments, the one or more functional groups are selected from one or more polar monomers. In some embodiments, each of the one or more polar monomers comprises a double bond, a triple bond, an aromatic, a hydroxyl, an ethoxy, an aldehyde, a carbonyl, a carboxyl, an amino, a mercapto, a halide, or combination thereof. In some embodiments, each of the one or more polar monomers comprises one or more heteroatoms, which in some embodiments are selected from nitrogen, oxygen, sulfur, phosphorus, chlorine, bromine, iodine, lithium, magnesium, or a combination thereof.

[0053] In some embodiments, each tagged polymer comprises the corresponding functional group in an amount in the range of from 50 ppmw to 20,000 ppmw, from 100 ppmw to 15,000 ppmw, or from 500 ppmw to 10,000 ppmw, based on the weight of each tagged polymer.

[0054] In some embodiments, each functional group is added to each corresponding polymer in the tagging system by adding the selected functional group to the polymer chain. In some embodiments, the functional group is added to the polymer chain by grafting the functional group to the polymer. In some embodiments, the functional group is added to the polymer chain copolymerization of the functional group as a monomeric unit in the polymer chain.Polymer identification

[0055] After polymers are tagged during manufacture to produce tagged polymers, the tagged polymers enter the stream of commerce after being incorporated into articles and / or packaging materials. After performing their intended purpose for the consumer, the articles and / or packaging materials complete their life cycle with disposal to waste by the consumer. Bulk waste is then processed to recover plastic waste, wherein the plastic waste contains a mixture of articles and / or packaging materials comprising a variety of polymers. At this point it is desirable to begin the process of reducing the amount of mixed polymer waste by identification of the tagged polymers.

[0056] Bulk waste can be processed at a materials recycling facility by a series of conveyor belts linking manual and / or automated sorting steps, which result in separation of the bulk waste into plastic waste suitable for recycling, non-plastics suitable for recycling, and other waste material suitable only for landfill and / or incineration. In some embodiments, the method disclosed herein provides for identification of tagged polymers in the plastic waste suitable for recycling.

[0057] In some embodiments, the method comprises detecting tagged polymers using devices suited for detecting the relevant tags. In embodiments wherein the tags comprise color agents, the means for detecting the one or more selected colors comprises human observation, a colorimeter, a spectrometer, or a combination thereof. In embodiments wherein the tags comprise additives suited to impart one or more selected light emission signatures, the means for detecting the one or more selected light emission signatures comprises a spectrometer, a spectroradiometer, a spectrophotometer, or a combination thereof. In embodiments wherein the tags comprise functional groups, wherein each functional group has a distinct near-IR signature, the means for detecting the one or more selected colors comprises a spectrometer, a spectroradiometer, a spectrophotometer, or a combination thereof.Polymer sorting

[0058] In some embodiments, the method further comprises separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more tags and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same tag.

[0059] In some embodiments, wherein each tag is a color agent, the method further comprises separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more colors and forming one or more collections of discreteportions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same color.

[0060] In some embodiments, wherein each tag is an additive having a specific light emission signature, the method further comprises separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more light emission signatures and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same light emission signatures.

[0061] In some embodiments, wherein each tag is a functional group having a specific near-IR signature, the method further comprises separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more near-IR signatures and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same near-IR signatures.Optional methods

[0062] In some embodiments, there can be primary and secondary sorting. For example, a polymer tagging system can include tagging of polyethylene, polypropylene, and nylon. A plastic waste stream can contain containers and films that are substantially pure polyethylene or polypropylene. The plastic waste stream can further include multilayer films and / or articles comprising polyethylene / nylon or polypropylene / nylon. A primary sort could be performed using a first type of tag and means for detecting the first type of tag to extract articles comprising polyethylene into a first population and articles comprising polypropylene into a second population.

[0063] Secondary sorting could be performed on each of the first population using a second type of tag and means for detecting the second type of tag to separate the first population into a first portion comprising substantially pure polyethylene and a second portion comprising a polyethylene / nylon mixture.

[0064] Secondary sorting could be performed on each of the second population using a second type of tag and means for detecting the second type of tag to separate the second population into a first portion comprising substantially pure polypropylene and a second portion comprising a polypropylene / nylon mixture.

[0065] Use of different tags and corresponding means for detecting such tags could be combined in two or more sorting steps to provide increasing levels of purity of multiple types of polymer waste.

[0066] In some embodiments, the amount of a tag can provide identification of different polymers. For example, a certain tag may be used to identify polyethylene, but a specific amount of the tag may be added in different amounts that correlates to the comonomer content, thereby providing an indicator for separation of the polyethylene waste into portions of LDPE, LLDPE, MDPE, and HDPE.

[0067] In some embodiments, a tag can be an artifact of the polymerization, such as, but not limited to one or more metals or other catalyst residue. In such instances, the method disclosed herein is enabled by selection of a means for detecting such materials.

[0068] In some embodiments, the method herein is useful for separating polar polymers from polyolefins and / or, separating polar polymers into populations having different types of comonomers and / or different amounts of comonomer. In some embodiments, differentiation of polar polymers is enabled by selection of a means for detecting and distinguishing types and amounts of polar comonomers.Certain embodiments

[0069] In a first group of embodiments, a method for identifying polymers comprises providing one or more unique tags corresponding to each of one or more polymers, respectively; and adding each of the unique tags to each of the corresponding polymers to produce one or more tagged polymers. In some embodiments, the method further comprises a means for detecting the one or more tags. The amount of each of the unique tags added to each of the corresponding polymers, respectively, is in the range of from an amount sufficient to be detected by the means for detecting the tags to an amount insufficient to cause an undesirable change in performance between each of the one or more polymers and each of the one or more tagged polymers, respectively. In some embodiments, in addition to the foregoing limitations, the method further comprises a means for separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more tags and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same tag.

[0070] In a second group of embodiments, in addition to the limitations of the first group of embodiments, the one or more tags comprise one or more color agents suited to impart one or more selected colors corresponding to each of the one or more tagged polymers.

[0071] In further embodiments of the second group of embodiments, the method is further characterized by one or more of the following: a) adding each of the color agents, comprises mixing each of the one or more polymers with a selected color agent from the one or more color agents, respectively, under compounding conditions; b) the color agents comprise additives emitting light at wavelengths in the visible range; c) the color agents comprise pigments, dyes, or a combination thereof; and d) the method further comprises a means for detecting the one or more selected colors.

[0072] In further embodiments of the second group of embodiments, embodiments comprising the means for detecting one or more selected colors are further characterized by one or more of the following: a) the means for detecting the one or more selected colors comprises human observation, a colorimeter, a spectrometer, or a combination thereof; b) each tagged polymer comprises the corresponding color agent in an amount in the range of from an amount sufficient to be detected by the means for detecting the corresponding color agent to an amount insufficient to cause an undesirable change in performance between each of the one or more polymers and each of the one or more tagged polymers, respectively; wherein in further embodiments, each tagged polymer comprises the corresponding color agent in an amount in the range of from 50 ppmw to 20,000 ppmw, from 100 ppmw to 15,000 ppmw, or from 500 ppmw to 10,000 ppmw, based on the weight of each tagged polymer; and c) the method further comprises a means for separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more selected colors, and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the color.

[0073] In a third group of embodiments, in addition to the limitations of the first group of embodiments, the one or more tags comprise one or more additives suited to impart one or more selected light emission signatures corresponding to each of the one or more tagged polymers.

[0074] In further embodiments of the third group of embodiments, the method is further characterized by one or more of the following: a) adding each of the one or more additives, comprises mixing each of the one or more polymers with a selected additive from the one or more additives, respectively, under compounding conditions; b) the additives comprise compositions emitting light at wavelengths in the near-IR range, the visible range, the UV range, or a combination thereof; c) the one or more additives include but are not limited to: molecules containing one or more hydroxyl groups, one or more amine groups, one or more carboxyl groups, or a combination thereof, which absorb in the near-IR region (e.g., alcohols, glycols, fatty acids, and amines); molecules which contain highly conjugated carbon-carbon double bonds, which absorb in the UV and visible light regions (e.g., 1,3 -butadiene, benzene, and beta-carotene); or a combination thereof; and d) the method further comprises a means for detecting the light emission signature of each of the selected one or more additives.

[0075] In further embodiments of the third group of embodiments, embodiments comprising the means for detecting the light emission signature of each of the selected one or more additives are further characterized by one or more of the following: a) the means for detecting the one or more distinct light emission signatures comprises a spectrometer, a spectroradiometer, a spectrophotometer, or a combination thereof; b) each tagged polymer comprises the corresponding additive in an amount in the range of from an amount sufficient to be detected by the means for detecting the corresponding light emission signature to an amount insufficient to cause an undesirable change in performance between each of the one or more polymers and each of the one or more tagged polymers, respectively; wherein in further embodiments, each tagged polymer comprises the corresponding additive in an amount in the range of from 50 ppmw to 20,000 ppmw, from 100 ppmw to 15,000 ppmw, or from 500 ppmw to 10,000 ppmw, based on the weight of each tagged polymer; andc) the method further comprises a means for separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting each of the one or more selected light emission signatures, and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same light emission signature.

[0076] In a fourth group of embodiments, in addition to the limitations of the first group of embodiments, the one or more tags comprise one or more functional groups, wherein each functional group has a distinct near-IR signature corresponding to each of the one or more tagged polymers.

[0077] In further embodiments of the fourth group of embodiments, the method is further characterized by one or more of the following: a) the one or more tags comprise one or more functional groups, wherein each functional group has a distinct near-IR signature; b) adding each of the one or more functional groups, comprises adding a selected functional group of the one or more functional groups to the polymer chain of each of the one or more polymers, respectively, by grafting, copolymerization, or a combination thereof; c) the one or more functional groups are selected from one or more polar monomers; wherein in further embodiments, each of the one or more polar monomers comprises: i) a double bond, a triple bond, an aromatic, a hydroxyl, an ethoxy, an aldehyde, a carbonyl, a carboxyl, an amino, a mercapto, a halide, or combination thereof; ii) one or more heteroatoms, which in some embodiments are selected from nitrogen, oxygen, sulfur, phosphorus, chlorine, bromine, iodine, lithium, magnesium, or a combination thereof; or iii) a combination thereof; and d) the method further comprises a means for detecting the distinct near-IR signature of each of the one or more functional groups.

[0078] In further embodiments of the fourth group of embodiments, embodiments comprising the means for detecting the distinct near-IR signature of each of the one or more functional groups are further characterized by one or more of the following:a) the means for detecting the one or more distinct near-IR signatures comprises a spectrometer, a spectroradiometer, a spectrophotometer, or a combination thereof; b) each tagged polymer comprises the corresponding functional group in an amount in the range of from an amount sufficient to be detected by the means for detecting the corresponding near-IR signature to an amount insufficient to cause an undesirable change in performance between each of the one or more polymers and each of the one or more tagged polymers, respectively; wherein in further embodiments, each tagged polymer comprises the corresponding functional group in an amount in the range of from 50 ppmw to 20,000 ppmw, from 100 ppmw to 15,000 ppmw, or from 500 ppmw to 10,000 ppmw, based on the weight of each tagged polymer; and c) the method further comprises a means for separating discrete portions of the one or more tagged polymers from a mixed plastic waste in response to detecting the one or more selected functional groups and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers having the same selected functional groups.

[0079] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, in addition to recited ranges, any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0080] All documents and references cited herein, including testing procedures, publications, patents, journal articles, etc., are herein fully incorporated by reference for all jurisdictions in which such incorporation is permitted and to the extent such disclosure is consistent with the description of the present invention.

[0081] Although the present invention and its 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 invention as defined by the appended claims.Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the processes, machines, means, methods, and / or steps described in the specification. As one of the ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, means, methods, and / or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein, may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, means, methods, and / or steps.

Claims

CLAIMSWhat is claimed is:

1. A method for sorting polymers, the method comprising: providing a mixed plastic waste stream comprising portions of one or more tagged polymers, wherein each of the one or more tagged polymers comprises a selected polymer and a corresponding selected tag; and identifying the one or more tagged polymers using a means for detecting the selected tag.

2. The method of claim 1, wherein the amount of the corresponding selected tag added to the selected polymer is in a range of from an amount sufficient to be detected by the means for detecting the tag to an amount insufficient to cause an undesirable change in performance between each of the polymers and each of the corresponding tagged polymers, respectively.

3. The method of claim 1, further comprising: separating each of the one or more tagged polymers from the mixed plastic waste stream in response to identifying the one or more tagged polymers; and forming one or more collections of discrete portions of each of the one or more tagged polymers, wherein each collection consists substantially of portions of tagged polymers having the same tag.

4. The method of claim 1, wherein each tag comprises a color agent suited to impart a selected color corresponding to each of the one or more tagged polymers.

5. The method of claim 4, wherein each selected color agent is mixed with each of the one or more polymers, respectively, under compounding conditions to form each of the one or more tagged polymers.

6. The method of claim 4, wherein the one or more color agents comprise pigments, dyes, or a combination thereof.

7. The method of claim 4, further comprising identifying the one or more tagged polymers using a means for detecting the one or more selected colors.

8. The method of claim 7, further comprising: separating the one or more tagged polymers from the mixed plastic waste stream in response to detecting the one or more selected colors; and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers comprising the same selected color agents.

9. The method of claim 1, wherein each tag comprises an additive suited to impart a selected light emission signature corresponding to each of the one or more tagged polymers.

10. The method of claim 9, wherein each selected additive is mixed with each of the one or more polymers, respectively, under compounding conditions to form each of the one or more tagged polymers.

11. The method of claim 9, wherein the one or more additives comprise compositions emitting light at wavelengths in the near-IR range, the visible range, the UV range, or a combination thereof.

12. The method of claim 9, wherein the one or more additives comprise molecules containing one or more hydroxyl groups, one or more amine groups, one or more carboxyl groups, or a combination thereof,); molecules which contain highly conjugated carbon-carbon double bonds; or a combination thereof.

13. The method of claim 9, further comprising identifying one or more tagged polymers using a means for detecting the light emission signature of each of the one or more selected additives.

14. The method of claim 13, further comprising: separating the one or more tagged polymers from the mixed plastic waste stream in response to detecting the one or more selected light emission signatures; andforming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers comprising the same selected additive.

15. The method of claim 1, wherein each tag comprises a functional group suited to impart a selected distinct near-IR signature corresponding to each of the one or more tagged polymers.

16. The method of claim 15, wherein each selected functional group is added to the polymer chain of each of the one or more polymers, respectively, by grafting, copolymerization, or a combination thereof, to form each of the one or more tagged polymers17. The method of claim 15, wherein the one or more functional groups comprise one or more polar monomers.

18. The method of claim 17, wherein each of the one or more polar monomers comprise a double bond, a triple bond, an aromatic, a hydroxyl, an ethoxy, an aldehyde, a carbonyl, a carboxyl, an amino, a mercapto, a halide, or combination thereof.

19. The method of claim 15, further comprising identifying tagged polymers using a means for detecting the distinct near-IR signature of each of the one or more functional groups.

20. The method of claim 19, further comprising: separating the one or more tagged polymers from the mixed plastic waste stream in response to detecting the one or more selected near-IR signatures; and forming one or more collections of discrete portions of the tagged polymers, wherein each collection consists substantially of tagged polymers comprising the same selected functional groups.

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