Method for purifying regenerated polymer

Abstract

Embodiments are directed to a method for purifying regenerated polymer.

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure are directed to methods for purifying polymers, and more specifically, regenerated polymers. [Background technology]

[0002] Currently, there is a high demand for polymers worldwide, with the consumption of polyethylene and polypropylene exceeding 100 million tons and 80 million tons, respectively, in 2020. This demand is expected to grow further, and it is at a time when it is increasingly necessary to limit the impact of plastics on the environment. Reusing or recycling plastic waste is advantageous not only in limiting the amount that irreversibly enters the environment, but also in reducing the amount of new or virgin polymers produced by energy- and CO2-intensive processes.

[0003] Mechanically recycled polymers are obtained by collecting and sorting post-consumer or post-industrial recycled materials into a mainly homogenous polymer stream, which is washed with aqueous and / or caustic solutions and then reprocessed into pellets of recycled polymer. However, the reprocessed pellets often remain contaminated with undesirable impurities such as organoleptic compounds, colorants, gels, heavy metals, and plasticizers that were added to the product for specific applications, along with other polymers that were not removed during the mechanical sorting process. These impurities result in recycled polymers with reduced physical properties that limit their reuse, and therefore are often downcycled into a limited number of less demanding applications, while ubiquitous sources of plastic waste such as multi-layer packaging and films are completely eliminated, since the polymers contained therein are not usable by current mechanical recycling methods.

[0004] Solvent-based methods have been developed to address the limitations of mechanical recycling, with the goal of removing at least a portion of these impurities to produce purer regenerated polymers with improved physical properties. The range of impurities removed can be adapted to different solvent-based process operations, including but not limited to dissolution, crystallization, precipitation, centrifugation, filtration, adsorption, and extraction, or combinations of these, each tailored to remove specific impurities. Solvent-based methods can produce purified polymers with properties close to those of virgin materials, but at higher costs and additional process risks. More complex processes for handling the solvent over a wide range of operating conditions require more expensive capital investments, energy, and other operating costs relative to mechanical recycling, as well as inducing complex phenomena such as fouling and clogging that can further increase costs and potentially make the entire process unfeasible. These problems are exacerbated as the variability of the recycled polymer-containing streams increases, and such variable streams must be recycled in large quantities if the fraction of recycled polymers on a global scale is to increase substantially. Amid these challenges, the purified regenerated polymers need to remain economically competitive with virgin materials. Clearly, selective and innovative combinatorial processes must be carefully designed for new solvent-assisted methods of purifying an expanded range of regenerated polymer sources that are operationally stable and economically viable. Summary of the Invention

[0005] The present disclosure provides a method for purifying reclaimed polymer, the method comprising: transferring the reclaimed polymer to a polymer dissolution vessel, the reclaimed polymer comprising solids; selectively dissolving the solid reclaimed polymer in the polymer dissolution vessel with a solvent to produce a polymer dissolution vessel composition, the polymer dissolution vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the polymer dissolution vessel composition to a filtration vessel to remove a first insoluble contaminant and produce a filtration vessel composition, the filtration vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the composition to a sorption separation vessel to remove the first soluble contaminant and produce a sorption separation vessel composition, the sorption separation vessel having a temperature of 70°C to 180°C and a pressure of 1 bar to 30 bar; transferring the sorption separation vessel composition to an extraction vessel to remove the first target portion of the solvent and the second soluble contaminant and produce an extraction vessel composition, the extraction vessel having a temperature of 130°C to 300°C and a pressure of 30 bar to 250 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove the second target portion of the solvent and the third soluble contaminant and produce a purified regenerated polymer.

[0006] The above summary of the present disclosure is not intended to describe each disclosed embodiment or to describe every implementation of the present disclosure. More specifically, the present specification illustrates exemplary embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. [Brief description of the drawings]

[0007] [Figure 1] 1 illustrates an example of a portion of a system in accordance with one or more embodiments of the present disclosure. [Diagram 2] 1 illustrates an example of a portion of a system in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Disclosed herein is a method for purifying recycled polymers. Advantageously, the method disclosed herein can provide improved contaminant removal efficiency compared to other polymer purification processes, can utilize solid polymer feeds with widely varying feedstocks, can provide reduced fouling compared to other polymer purification processes, and / or can provide purified recycled polymers with certain properties that are desirable for various applications, such as improved, e.g., lower residual solvent content, improved, e.g., lower odor, and / or improved, e.g., lower color. The method of purifying regenerated polymer disclosed herein includes transferring the regenerated polymer to a polymer dissolution vessel, the regenerated polymer comprising solids; selectively dissolving the solid regenerated polymer in the polymer dissolution vessel with a solvent to produce a polymer dissolution vessel composition, the polymer dissolution vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the polymer dissolution vessel composition to a filtration vessel to remove a first insoluble contaminant to produce a filtration vessel composition, the filtration vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; and collecting the filtration vessel composition. and transferring the sorption separation vessel composition to a sorption separation vessel to remove the first soluble contaminant and produce a sorption separation vessel composition, the sorption separation vessel having a temperature of 70°C to 180°C and a pressure of 1 bar to 30 bar; transferring the sorption separation vessel composition to an extraction vessel to remove the first target portion of the solvent and the second soluble contaminant and produce an extraction vessel composition, the extraction vessel having a temperature of 130°C to 300°C and a pressure of 30 bar to 250 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove the second target portion of the solvent and the third soluble contaminant and produce a purified regenerated polymer. One or more embodiments provide that a solid medium, as further discussed herein, can be added to the filtration vessel, for example, such that the solid medium provides a filter aid. The vessels referred to herein can be in series, parallel, or a combination thereof.The embodiments provide that the method for purifying the regenerated polymer as disclosed herein can be a continuous process, a batch process, or a combination thereof.

[0009] Surprisingly, it has been found that selective dissolution of the recycled polymer as a first process step, e.g., before the filtration, sorption, and extraction steps, can reduce process fouling / clogging and provide a more consistent and / or improved composition of the purified recycled polymer. The selective dissolution step can help minimize the formation of a second polymer liquid phase, as discussed herein. Without selective dissolution, as discussed herein, different polymers such as polyethylene and polypropylene may form individual liquid phases with the solvent if the solvent favors one polymer over the other, e.g., n-butane is more likely to stay with polypropylene compared to polyethylene. The polyethylene-solvent phase may be heavier than the polypropylene-solvent phase. The density difference between such two phases may be smaller at lower temperatures. This undesirable phase separation can affect the quality of the purified recycled polymer and cause process problems. The light polypropylene phase, which attracts more solvent, is not favorable for the recycling of mainly polyethylene, where the polyethylene is more concentrated (viscous) and contains most of the non-dissolved heavy contaminants.

[0010] As used herein, the term "recycled polymer" refers to a polymer that has been used for a previous purpose and then recovered for further processing. For example, "recycled polymer" can refer to a polymer recovered from post-consumer materials as defined by ISO 14021, a polymer recovered from pre-consumer materials as defined by ISO 14021, and combinations thereof. Thus, the general term post-consumer materials includes blends of polymers recovered from materials generated by households or commercial, industrial, and business facilities in their role as end users of materials that can no longer be used for their intended purpose. The general term post-consumer materials also includes blends of polymers recovered from the return of materials from the distribution chain. The general term pre-consumer materials includes blends of polymers recovered from materials diverted from waste streams during manufacturing processes. The general term pre-consumer materials excludes the reuse of materials such as reprocessed, reground, or scrap that are generated in a process and can be reused within the same process that generated it. Recycled polymers may include polymers or blends of polymers recovered from post-consumer materials, pre-consumer materials, or combinations thereof.

[0011] Recycled polymers are different from virgin polymers. "Virgin polymer" refers to a polymer that can be characterized as a "primary (virgin) material" as defined by ISO 18604. The term virgin polymer can include polymers that have never been processed into any form of end-use product. Virgin polymers may also be referred to by a variety of other terms.

[0012] The regenerated polymer can be collected and processed prior to purification by the methods disclosed herein. For example, for pre-purification, the regenerated polymer can be shredded, washed, subjected to metal reduction, e.g., removal, density separated, dried, and / or screened.

[0013] The recycled polymer can be a homopolymer, copolymer, or combination thereof. Examples of recycled polymers include polyolefins such as polyethylene and polypropylene, polyesters such as poly(ethylene terephthalate), vinyl polymers such as poly(vinyl chloride), acrylonitrile, butadiene and styrene homopolymers and interpolymers, polyesters such as poly(ethylene terephthalate) and poly(bisphenol-A carbonate), polyamides such as nylon 66, polycarbonates such as poly(bisphenol-A carbonate), acrylics such as poly(methyl methacrylate), fluorocarbon polymers, polyethers, polysaccharides, silicones such as poly(dimethylsiloxane), thermoplastic elastomers such as ethylene-propylene rubber, among others.

[0014] Recycled polymers may contain some contaminants, such as cellulose fibers, rubbers, e.g., nitrile rubber, fillers, e.g., calcium carbonate, pigments, dyes, processing aids, stabilizing additives and their decomposition products, inks, adhesives, dirt and rocks, crosslinked polymers, and other performance additives, such as plasticizers, slip agents, and antiblock agents, among other contaminants. Examples of contaminants include organoleptic compounds such as aldehydes, ketones, esters, organic pigments such as diazo pigments (yellow), phthalocyanine green, phthalocyanine blue, lithole (red), inorganic pigments such as titanium dioxide (white), carbon black, cadmium selenium sulfide (red), molybdate orange, lead chromate (yellow), glycerol monostearate and PEG (antistatic agents), erucamide and oleamide (slip promoters), hindered phenols and phosphite antioxidants, polyisobutylene as adhesives, hindered amines as UV stabilizers, and calcium carbonate, talc, and glass fibers (fillers), among other contaminants.

[0015] An embodiment of the present disclosure provides that the regenerated polymer is soluble in a solvent. As used herein, the terms "soluble", "soluble" and "dissolved" refer to the association of molecules or ions of a solute (e.g., the regenerated polymer) with molecules of a solvent, i.e., the action of solvation, which results in the incorporation of the solute into the solvent. The stability of a solute dissolved in a solvent strongly depends on the interactions between the solute molecules, the solvent molecules, and the molecules with each other. The favorability of a solute-solvent pair can be estimated by calculating the associated Hildebrand or Hansen solubility parameters, two such methods being examples suitable for polymers and solvents. The thermodynamic stability of a mixture can be evaluated by the following formula: ΔGmix=ΔHmix-TΔSmix, where ΔGmix is ​​the Gibbs free energy change of mixing of the solute and the solvent, ΔHmix is ​​the enthalpy change of mixing, T is the absolute temperature, and ΔSmix is ​​the entropy of mixing. A solute dissolved in a solvent is stable at a given temperature and pressure if the Gibbs free energy changes of mixing of the solute and the solvent are both negative and are minimized.

[0016] As used herein, the terms "insoluble," "insoluble," and "non-soluble" may be used interchangeably.

[0017] 1 illustrates an example of a portion of a purification system 102 according to one or more embodiments of the present disclosure. The purification system 102 may include a polymer dissolution vessel 104. As used herein, "a," "an," or "a number of" can refer to one or more of something. For example, a polymer dissolution vessel can refer to one or more polymer dissolution vessels, such as vessels in series, vessels in parallel, or a combination thereof.

[0018] The figures herein follow a numbering convention in which the first digit or digits correspond to the figure number of the figure, and the remaining digits identify an element or component within the figure. Similar elements or components among different numbers can be identified by using similar numbers. For example, 104 can designate element "04" in FIG. 1, and a similar element can be designated as 204 in FIG. 2. Multiple elements or components that are similar in the figures can include a letter indicating that the elements or components are similar. For example, in FIG. 2, "204A" is similar to "204B," both of which are similar to 104 in FIG. 1.

[0019] The polymer dissolution vessel 104 may be made of various materials and may have different shapes and / or sizes for various applications. As used herein, the term "vessel" refers to a tank, pipe, separator, decanter, column, heat exchanger, extruder, and / or other fluid processing hardware. The polymer dissolution vessel 104 may include several known components, such as an agitator and / or heating coil. The polymer dissolution vessel 104 may include several inputs and / or outputs. For example, the polymer dissolution vessel 104 may include an input 106. The input 106 may be utilized to transfer the regenerated polymer to the polymer dissolution vessel 104.

[0020] The embodiment provides that the recycled polymer transferred to the polymer dissolution vessel 104 is in a solid, e.g., solid state, rather than a liquid state. The solid recycled polymer may be crystalline, semi-crystalline, amorphous, or a combination thereof. Transferring the solid recycled polymer to the polymer dissolution vessel 104 can reduce costs associated with melting the recycled polymer transferred to the polymer dissolution vessel 104, can reduce processing complexities associated with melting the recycled polymer transferred to the polymer dissolution vessel 104, and / or can aid in selective dissolution of the transferred recycled polymer in the polymer dissolution vessel 104.

[0021] The solid recycled polymer may have a variety of shapes and / or sizes. For example, the solid recycled polymer may be pieces, spheres, cylinders, pellets, or combinations thereof, among other shapes. The solid recycled polymer may have an average diameter of 1 to 200 millimeters (mm).

[0022] The polymer dissolution vessel 104 can include an input 108. The input 108 can be utilized to transfer a solvent to the polymer dissolution vessel 104. An embodiment provides that the solvent is maintained as a liquid within the polymer dissolution vessel 104, for example, utilizing an appropriate temperature and pressure.

[0023] The embodiment provides that the solvent selectively dissolves the solid regenerated polymer transferred to the polymer dissolution vessel 104 to create the polymer dissolution vessel composition. In other words, at the temperature and pressure of the polymer dissolution vessel 104, the solvent selectively dissolves the solid regenerated polymer. For example, the solubility of the polymer in the solvent for selective dissolution may depend on the solvent / polymer interaction, the dissolution temperature, and the crystallinity of the polymer. For example, for dissolution of a semi-crystalline polymer, the solvent can diffuse to the surface of the polymer and dissolve part of the semi-crystalline structure so that the polymer can swell and remove the amorphous layer. The dissolution rate may depend on many factors, including but not limited to the crystallinity of the regenerated polymer, the agitator speed utilized, the temperature, pressure, solid size, and / or the solvent composition. The dissolution rates of polymers with similar melting points and sizes may differ significantly. As the dissolution temperature, pressure, and / or dissolution time change, multiple liquid phases may form and potentially multiple polymers may be dissolved. However, the formation of multiple liquid polymer phases is undesirable as it can impair the mechanical quality of the product and / or cause process fouling.

[0024] The polymer dissolution vessel composition may include a solvent, dissolved reclaimed polymer, and a number of contaminants that may be dissolved or undissolved. Contaminants that may be dissolved or undissolved include many of those previously described. Contaminants that may not be dissolved, such as insoluble contaminants, include pigments, cellulose fibers, calcium carbonate, talc, mud, and adhesives, among other contaminants. Polymers other than the reclaimed polymer that are selectively dissolved may be undissolved or dissolved contaminants. However, as further described herein, polymers other than the reclaimed polymer may be purified in a parallel process.

[0025] The solvent can be selected based on the solid recycled polymer to be selectively dissolved. In other words, different solvents can be used for different solid recycled polymers. Examples of solvents include, among others, aliphatic, aromatic or cyclic saturated or unsaturated hydrocarbons, alcohols, carboxylic acids, esters, ketones, amines, and halogenated solvents. One or more embodiments provide that the solvent is selected from ketones, alcohols, ethers, esters, alkenes, alkanes, and combinations thereof. One or more embodiments provide that the solvent is selected from acetone, methyl ethyl ketone, methanol, ethanol, propanol, isopropanol, dimethyl ether, diethyl ether, ethyl methyl ether, methyl acetate, ethyl acetate, ethylene, propylene, 1-butene, 2-butene, isobutylene, pentene, cyclopentene, isomers of pentene, hexene, cyclohexene, 1-methyl-cyclopentene, isomers of hexene, heptene, cycloheptene, 1-methyl-1-cyclohexene, isomers of heptene, methane, ethane, propane, n-butane, isobutane, n-pentane, cyclopentane, isomers of pentane, n-hexane, cyclohexane 1-methyl-1-cyclopentane, isomers of hexane, heptane, cycloheptane, 1-methyl-1-cyclohexane, dimethylcyclopentane, and isomers of heptane. One or more embodiments provide that the solvent is an alkane, such as a C3-C12 alkane, a C4-C10 alkane, a C5-C7 alkane, or a C5-C6 alkane. For example, one or more embodiments provide that the solid recycled polymer is polyethylene and the solvent is pentane.

[0026] One or more embodiments provide that the solvent has a boiling point of 25°C to 90°C. All individual values ​​and subranges between 25°C to 90°C are included, for example, the solvent can have a boiling point from 25, 28, or 30°C as a lower limit to 90, 80, or 70°C as an upper limit. As used herein, "boiling point" refers to the boiling point at an absolute pressure of exactly 100 kPa (1 bar, 14.5 psia, 0.9869 atm) as established by the International Union of Pure and Applied Chemistry (IUPAC). One or more embodiments provide that a low boiling point solvent is utilized, for example, having a boiling point of 25°C to 75°C. By utilizing a low boiling point solvent, the residual solvent in the final purified regenerated polymer can be reduced.

[0027] As used herein, "solvent" refers to a single solvent, such as pentane, or a combination of solvents, such as pentane and diethyl ether. An embodiment provides that when a combination of solvents is utilized, each of the solvents in the solvent combination has a boiling point within 20°C of each other. One or more embodiments provide that when a combination of solvents is utilized, each of the solvents in the solvent combination has a boiling point within 15, 10, or 5°C of each other. The solvent can be added at various points in the process. For example, the solvent may be added to the polymer dissolution vessel 104, the filtration vessel 112, the sorption separation vessel 118, and / or the extraction vessel 124. One or more embodiments provide that the single solvent utilized to selectively dissolve the solid regenerated polymer transferred to the polymer dissolution vessel is 100% by weight of the total weight of the solvent utilized in the process. For example, if the solid regenerated polymer is polyethylene and the solvent, such as the single solvent, is pentane, one or more embodiments provide that only pentane is utilized, such as no other solvents.

[0028] The solvent can be 80-95 wt% based on the total weight of the solid recycled polymer and solvent transferred to the polymer dissolution vessel to make the polymer dissolution vessel composition. All individual values ​​and subranges between 80-95 wt% are included, for example, the solvent can be from a lower limit of 80, 82, or 85 wt% to an upper limit of 95, 93, or 90 wt% based on the total weight of the solid recycled polymer and solvent transferred to the polymer dissolution vessel to make the polymer dissolution vessel composition.

[0029] Similarly, the solid recycled polymer can be 5-20% by weight based on the total weight of the solid recycled polymer and solvent transferred to the polymer dissolution vessel to make the polymer dissolution vessel composition, including all individual values ​​and subranges between 5-20% by weight, for example, the solid recycled polymer can be from a lower limit of 5, 7, or 10% by weight to an upper limit of 20, 18, or 15% by weight based on the total weight of the solid recycled polymer and solvent transferred to the polymer dissolution vessel to make the polymer dissolution vessel composition.

[0030] The solid regenerated polymer transferred to the polymer dissolution vessel 104 may contact the solvent in the polymer dissolution vessel for different times, e.g., different residence times, for various applications. For example, the solid regenerated polymer transferred to the polymer dissolution vessel may have an average residence time in the polymer dissolution vessel of 0.01 to 3 hours. All individual values ​​and subranges from 0.01 to 3 hours are included, for example, the solid regenerated polymer transferred to the polymer dissolution vessel may have an average residence time in the polymer dissolution vessel of 0.01, 0.05, or 0.1 hours at lower limits to 3, 2, or 0.5 hours at upper limits.

[0031] The polymer dissolution vessel 104 can have a temperature, for example, an operating temperature, between 70°C and 180°C. Utilizing a temperature between 70°C and 180°C can provide for selective dissolution of the solid recycled polymer in the solvent. All individual values ​​and subranges between 70°C and 180°C are included, for example, the polymer dissolution vessel can have a temperature from a lower limit of 70, 90, or 110°C to an upper limit of 180, 160, or 140°C. One or more embodiments provide that, for example, when the recycled polymer is polyethylene, the polymer dissolution vessel can have a temperature between 70°C and 130°C. One or more embodiments provide that, for example, when the recycled polymer is polypropylene, the polymer dissolution vessel can have a temperature between 110°C and 180°C.

[0032] The polymer dissolution vessel 104 can have a pressure, e.g., an operating pressure, between 1 bar and 30 bar absolute. Unless otherwise specified, pressures reported herein are absolute pressures. Utilizing a pressure between 1 bar and 30 bar can provide that the solid regenerated polymer is selectively dissolved in the solvent, while the solvent remains in a liquid state. All individual values ​​and subranges between 1 bar and 30 bar are included, e.g., the polymer dissolution vessel can have a pressure from 1, 2, or 3 bar as a lower limit to 30, 25, or 15 bar as an upper limit.

[0033] The polymer dissolution vessel 104 may include a discharge 110. The discharge 110 may be utilized to transfer the polymer dissolution vessel composition to a filter vessel 112. The filter vessel 112 may be made from a variety of materials and may have different shapes and / or sizes for various applications. The filter vessel 112 may include a variety of filter media, such as cloth, wool, linen, fiberglass, steel mesh, sintered metal, and combinations thereof. The filter vessel 112 may include a number of known components. The filter vessel 112 may include a solid bowl centrifuge, a self-cleaning strainer, a drum filter, a candle filter, a leaf filter, and / or a rotary pressure filter, among others.

[0034] One or more embodiments provide that the filter vessel 112 can provide solid-liquid separation. For example, one or more insoluble solids (undissolved solids), e.g., undissolved contaminants, from the polymer dissolution vessel composition transferred to the filter vessel 112 can be separated from the liquid and soluble, e.g., dissolved, components of the polymer dissolution vessel composition to create the filter vessel composition. The insoluble contaminants, e.g., the separated undissolved solids, can be removed via the discharge 114, which may include some incidental solvent removal. By removing the undissolved contaminants, the filter vessel composition can be created. The soluble (dissolved) regenerated polymer, e.g., the filter vessel composition, can be in a liquid phase, e.g., in a solution or molten state.

[0035] The polymer dissolution vessel composition transferred to the filtration vessel 112 may have different residence times for various applications. For example, the polymer dissolution vessel composition transferred to the filtration vessel may have an average residence time in the filtration vessel of 0.01 to 12 hours, including all individual values ​​and subranges from 0.01 to 12, for example, the polymer dissolution vessel composition transferred to the filtration vessel may have an average residence time in the filtration vessel of 0.01, 0.05, or 0.1 hours, to an upper limit of 12, 9, or 6 hours.

[0036] The filtration vessel 112 can have a temperature, e.g., an operating temperature, between 70° C. and 180° C. All individual values ​​and subranges between 70° C. and 180° C. are included, for example, the filtration vessel can have a temperature from a lower limit of 70, 100, or 110° C. to an upper limit of 180, 160, or 140° C. One or more embodiments provide that, for example, when the recycled polymer is polyethylene, the filtration vessel can have a temperature between 70° C. and 130° C. One or more embodiments provide that, for example, when the recycled polymer is polypropylene, the filtration vessel can have a temperature between 110° C. and 180° C.

[0037] The filtration vessel 112 can have a pressure, e.g., an operating pressure, between 1 bar and 30 bar, including all individual values ​​and subranges between 1 bar and 30 bar, e.g., the filtration vessel can have a pressure from 1, 2, or 3 bar as a lower limit to 30, 25, or 15 bar as an upper limit.

[0038] One or more embodiments provide that the polymer dissolution vessel 104 and the filtration vessel 112 each have a temperature within 20° C. of each other, each have a temperature within 10° C. of each other, or each have a temperature within 5° C. of each other. One or more embodiments provide that the polymer dissolution vessel 104 and the filtration vessel 112 are operated isothermally, e.g., the polymer dissolution vessel 104 and the filtration vessel 112 are operated at essentially the same temperature.

[0039] One or more embodiments provide that the polymer dissolution vessel 104 and the filtration vessel 112 have pressures within 10 bar of each other, within 5 bar of each other, within 3 bar of each other, or within 1 bar of each other.

[0040] The filtration vessel 112 can include a discharge 116. The discharge 116 can be utilized to transfer the filtration vessel composition to a sorption separation vessel 118. The sorption separation vessel can be made from a variety of materials and can have different shapes and / or sizes for various applications. The sorption separation vessel 118 can include a number of known components. The sorption separation vessel 118 can be a batch, continuous moving, continuous fixed bed, continuous fluidized bed, or pulsed bed vessel.

[0041] The sorption separation vessel 118 can include a solid medium that can be utilized to remove contaminants from the filtration vessel composition transferred to the sorption separation vessel 118. For example, the solid medium can be utilized to remove contaminants, e.g., the first soluble contaminant, by adsorption, absorption, electrostatics, size exclusion, ion exclusion, ion exchange, and / or other mechanisms that may be apparent to one skilled in the art. By way of example, pigments and many other contaminants that may be found in regenerated polymers may be polar compounds or have polar compounds on their surfaces and may preferentially interact with solid media that may also be at least slightly polar. These polar-polar interactions may be particularly advantageous when non-polar solvents such as alkanes are used as solvents.

[0042] The solid media may be inorganic materials, carbon-based materials, and combinations thereof. Examples of solid media include zeolites, activated carbon, silica gel, diatomaceous earth, perlite, clay, sand, molecular sieves, glass fiber, and cellulosic materials. One or more embodiments provide that the solid media is selected from zeolites, activated carbon, activated alumina, diatomaceous earth, and combinations thereof. The solid media may be maintained in the sorption separation vessel 118 by known components, such as a solid media container. The solid media may be a fluidized bed, may be agitated, may move in a mass, or may be maintained in a stationary position in the sorption separation vessel 118.

[0043] The filter vessel composition transferred to the sorption separation vessel 118 may contact the solid media in the sorption separation vessel for different times, e.g., different residence times, for various applications. For example, the filter vessel composition transferred to the sorption separation vessel 118 can have an average residence time in the sorption separation vessel of 0.01 to 12 hours. All individual values ​​and subranges from 0.01 to 12 hours are included, for example, the filter vessel composition transferred to the sorption separation vessel can have an average residence time in the sorption separation vessel of 0.01, 0.05, or 0.1 hours, to upper limits of 12, 9, or 6 hours.

[0044] The sorption separation vessel 118 can have a temperature, e.g., an operating temperature, between 70° C. and 180° C. All individual values ​​and subranges between 70° C. and 180° C. are included, for example, the sorption separation vessel can have a temperature from a lower limit of 70, 90, or 110° C. to an upper limit of 180, 160, or 140° C. One or more embodiments provide that, for example, when the recycled polymer is polyethylene, the sorption separation vessel can have a temperature between 70° C. and 130° C. One or more embodiments provide that, for example, when the recycled polymer is polypropylene, the sorption separation vessel can have a temperature between 110° C. and 180° C.

[0045] The sorption separation vessel 118 can have a pressure, e.g., an operating pressure, between 1 bar and 30 bar, including all individual values ​​and subranges between 1 bar and 30 bar, e.g., the sorption separation vessel can have a pressure from a lower limit of 1, 2, or 3 bar to an upper limit of 30, 20, or 15 bar.

[0046] One or more embodiments provide that the polymer dissolution vessel 104, the filtration vessel 112, and the sorption separation vessel 118 each have a temperature within 20° C. of each other, each have a temperature within 10° C. of each other, or each have a temperature within 5° C. of each other. One or more embodiments provide that the polymer dissolution vessel 104, the filtration vessel 112, and the sorption separation vessel 118 are operated isothermally, e.g., the polymer dissolution vessel 104, the filtration vessel 112, and the sorption separation vessel 118 are operated at essentially the same temperature.

[0047] One or more embodiments provide that the polymer dissolution vessel 104, the filtration vessel 112, and the sorption separation vessel 118 each have a pressure within 10 bar of each other, each have a pressure within 5 bar of each other, each have a pressure within 3 bar of each other, or each have a pressure within 1 bar of each other.

[0048] A sorption separation vessel composition can be provided by utilizing a solid medium to remove the first soluble contaminants, e.g., non-dissolved contaminants. Because the first soluble contaminants are removed by utilizing the sorption separation vessel 118 (and solid medium), the sorption separation vessel composition is less contaminated compared to the filtration vessel composition.

[0049] One or more embodiments provide that the sorption separation vessel can be combined with the filtration vessel, for example with a solid medium applied as a filter aid. For example, the filter aid can be stirred and continuously regenerated. One or more embodiments provide that the sorption separation vessel can be omitted, for example, the filtration vessel composition can be transferred to an extraction vessel.

[0050] After the filtration vessel composition transferred to the sorption separation vessel contacts the solid media to create the sorption separation vessel composition, the solid media can be regenerated, for example, when the solid media is approaching the limits of its contaminant removal capacity. Embodiments provide that the solid media can be regenerated in situ or the solid media can be removed from the sorption separation vessel 118 for regeneration, for example, by outlet 120. Known regeneration components and processes can be utilized.

[0051] After or while the filtration vessel composition being transferred to the sorption separation vessel contacts the solid media to create the sorption separation vessel composition, a drain 122 can be utilized to transfer the sorption separation vessel composition to an extraction vessel 124. The dissolved regenerated polymer, e.g., the sorption separation vessel composition, can be in a liquid phase, e.g., in a solution or molten state. The extraction vessel can be made from a variety of materials and can have different shapes and / or sizes for various applications.

[0052] The extraction vessel 124 may include a number of known components. The extraction vessel 124 may be, for example, a separator, a decanter, or an extraction column.

[0053] One or more embodiments provide that the extraction vessel 124 utilizes conditions, e.g., temperature and pressure, such that liquid-liquid extraction occurs. In other words, the conditions in the extraction vessel 124 may provide that the sorption separation vessel composition transferred to the extraction vessel 124 and the extraction vessel composition created by removing the first target portion of the solvent and the second soluble contaminant are maintained in the liquid phase.

[0054] One or more embodiments provide that the extraction vessel 124 utilizes conditions, such as temperature and pressure, such that supercritical extraction occurs. As described above, the extraction vessel composition created by removing the first target portion of the solvent and the second soluble contaminant can be maintained in a supercritical phase for some embodiments. The supercritical fluid is above its critical temperature and pressure, such as above the critical point of the fluid. In this supercritical region, the supercritical fluid can enhance the removal of contaminants, such as the second soluble contaminant, e.g., a contaminant that has a relatively high boiling point compared to other contaminants. The operating pressure and temperature can depend on the selection of the solvent and the solvent concentration, e.g., the amount of solvent utilized with a particular amount of regenerated polymer. The supercritical separation can be performed with both a solvent-rich liquid phase and a polymer-rich liquid phase present. The partitioning of the contaminant into the two phases can also be sensitive to the pressure and temperature utilized.

[0055] The sorption separation vessel composition transferred to the extraction vessel can have different residence times for various applications. For example, the sorption separation vessel composition transferred to the extraction vessel can have an average residence time in the extraction vessel of 0.01 to 3 hours. All individual values ​​and subranges from 0.01 to 3 hours are included, for example, the sorption separation vessel composition transferred to the extraction vessel can have an average residence time in the extraction vessel of 0.01, 0.05, or 0.1 hours at lower limits, to 3, 2, or 1.5 hours at upper limits.

[0056] One or more embodiments provide that a portion of the extraction vessel composition can be removed from the extraction vessel 124 by draining 126. The portion of the extraction vessel composition removed by draining 126 can include the first target portion of the solvent and the second soluble contaminant. One or more embodiments provide that a sorption separation can be performed following the extraction vessel.

[0057] The portion of the extraction vessel composition removed from the extraction vessel 124 by drain 126 can be from 15 to 90 weight percent of the material transferred to the extraction vessel, e.g., the sorption separation vessel composition transferred to the extraction vessel. All individual values ​​and subranges from 15 to 90 weight percent are included, e.g., the portion of the extraction vessel composition removed from the extraction vessel by drain 126 can be from a lower limit of 15, 20, or 25 weight percent to an upper limit of 90, 85, or 80 weight percent.

[0058] Similarly, the first target portion of solvent removed from the extraction vessel 124 by drain 126 can be 15-95% by weight of the solvent, e.g., the solvent transferred to the polymer dissolution vessel 104 and other solvents input to the system 102. All individual values ​​and subranges from 15-95% by weight are included, e.g., the first target portion of solvent removed from the extraction vessel by drain 126 can be from a lower limit of 15, 20, or 25% by weight to an upper limit of 95, 90, or 85% by weight, based on the total weight of solvent transferred to the polymer dissolution vessel 104.

[0059] As described above, the second soluble contaminants can be removed from the extraction vessel 124 by exhaust 126. The second soluble contaminants include non-volatile contaminants. Examples of the second soluble contaminants include organoleptic agents, antioxidants, plasticizers, antiblocking agents, antistatic agents, adhesives, ink ingredients, and combinations thereof. Varying amounts of the second soluble contaminants can be removed from the extraction vessel 126 for different applications.

[0060] The extraction vessel 124 can have an operating temperature, for example, between 130° C. and 300° C. All individual values ​​and subranges between 130° C. and 300° C. are included, for example, the extraction vessel can have a temperature from a lower limit of 130, 160, or 190° C. to an upper limit of 300, 280, or 260° C.

[0061] The extraction vessel 124 can have a pressure, e.g., an operating pressure, between 30 bar and 250 bar, including all individual values ​​and subranges between 30 bar and 250 bar, e.g., the extraction vessel can have a pressure from a lower limit of 30, 50, or 70 bar to an upper limit of 250, 220, or 180 bar.

[0062] After or while the first target portion of the solvent and the second soluble contaminant are removed from the extraction vessel 124 by discharge 122, the remaining portion of the extraction vessel composition can be transferred to the polymer concentrate vessel 130. The polymer concentrate vessel may be made from a variety of materials and may have different shapes and / or sizes for various applications. The polymer concentrate vessel 130 may include several known components, such as a throttle valve, a heater, a separator, a devolatilizing extruder, or a gas purge. Although a single polymer concentrate vessel 130 is shown, the embodiment is not so limited. For example, the polymer concentrate vessel 130 may include one or more flash vessels. By way of example, the polymer concentrate vessel 130 may include a series of, for example, three flash vessels, such as flash separators / flash drums.

[0063] The remaining portion of the extraction vessel composition, which may be, for example, a fluid phase, transferred to the polymer concentrate vessel 130, may be subjected to a reduction in pressure, for example, by passing through one or more throttling valves or other throttling devices. One or more embodiments provide that the polymer concentrate vessel 130 may utilize a series of reduced pressures, for example, a particular reduced pressure being lower relative to a preceding reduced pressure, to remove the second target portion of the solvent and the third soluble contaminants to create a purified regenerated polymer. The second target portion of the solvent and the third soluble contaminants may be removed from the polymer concentrate vessel 130 by exhaust 132.

[0064] The second target portion of solvent removed from the polymer concentrate vessel 130 by drain 132 can be 5-85 weight percent of the solvent, e.g., the solvent transferred to the polymer dissolution vessel 104. All individual values ​​and subranges from 5-85 weight percent are included, e.g., the second target portion of solvent removed from the polymer concentrate vessel 130 by drain 132 can be from a lower limit of 5, 10, or 15 weight percent to an upper limit of 85, 80, or 75 weight percent, based on the total weight of solvent transferred to the polymer dissolution vessel 104.

[0065] One or more embodiments provide that 75-99.9999 weight percent of the total solvent fed to the system 102 can be separated from the purified reclaimed polymer. All individual values ​​and subranges from 75-99.9999 weight percent are included, for example, the weight percent of the total solvent fed to the system that can be separated from the purified reclaimed polymer can be from a lower limit of 75, 85, or 95 weight percent to an upper limit of 99.9999 weight percent.

[0066] Examples of the third soluble contaminant include organoleptics, antioxidants, plasticizers, antiblocking agents, antistatic agents, ink ingredients, and combinations thereof that are not removed from the extraction vessel 124 by draining 126. One or more embodiments provide that the third soluble contaminant has a lower boiling point than the first soluble contaminant and the second soluble contaminant.

[0067] The polymer concentrator vessel 130 can have an operating temperature, for example, between 130° C. and 300° C. All individual values ​​and subranges between 130° C. and 300° C. are included, for example, the polymer concentrator vessel can have a temperature from a lower limit of 130, 150, or 170° C. to an upper limit of 300, 270, or 240° C.

[0068] The polymer concentrate vessel 130 can have a pressure, e.g., operating pressure, from 0.02 bar (e.g., vacuum) to 50 bar, including all individual values ​​and subranges between 0.02 bar and 50 bar, e.g., the polymer concentrate vessel can have a pressure from a lower limit of 0.02, 0.03, or 0.04 bar to an upper limit of 50, 40, or 30 bar.

[0069] The purified regenerated polymer can be removed from the polymer concentrate vessel 130 via discharge 134. After being removed from the polymer concentrate vessel 130, the purified regenerated polymer can undergo several further processing steps, such as pelletizing.

[0070] The purified recycled polymers can have several desirable properties for various applications, for example, they can provide low residual solvents, low odor, low gels, desirable color, and / or good mechanical properties, while exhibiting reduced levels of regulated contaminants, such as some of the contaminants mentioned above.

[0071] One or more embodiments provide that a solid medium may be utilized with, e.g., added to, filtration vessel 112, as described above. For example, a solid medium may be utilized as a filter aid for many applications, as described above. Because a solid medium is utilized with filtration vessel 112, one or more embodiments provide that a filtration vessel composition made utilizing the solid medium is transferred to extraction vessel 124. In other words, one or more embodiments provide that filtration vessel 112 and sorption separation vessel 118 are combined, as shown in FIG. 1, such that, for example, sorption separation vessel 118 may be eliminated.

[0072] In embodiments in which a solid medium is utilized with a filtration vessel, the second undissolved contaminants are removed as described above, for example, to produce a filtration vessel composition rather than a sorption separation vessel composition, which can then be transferred to an extraction vessel as described above.

[0073] In embodiments in which a solid medium is utilized with a filtration vessel, the polymer dissolution vessel and the filtration vessel may each have a temperature within 20° C. of each other, each may have a temperature within 10° C. of each other, or each may have a temperature within 5° C. of each other. One or more embodiments provide that the polymer dissolution vessel and the filtration vessel are operated isothermally, e.g., the polymer dissolution vessel and the filtration vessel are operated at essentially the same temperature.

[0074] In embodiments where a solid media is utilized in conjunction with a filtration vessel, the polymer dissolution vessel and the filtration vessel may each have a pressure within 10 bar of each other, each may have a pressure within 5 bar of each other, each may have a pressure within 3 bar of each other, or each may have a pressure within 1 bar of each other.

[0075] In one or more embodiments, the solvent can be purified in a separate process step and recycled to the dissolution and / or extraction vessel, thus reducing the amount of fresh solvent required for the process.

[0076] 2 illustrates an example of a portion of a system 260 according to one or more embodiments of the present disclosure. System 260 may be utilized, for example, when more than one regenerated polymer is to be purified.

[0077] System 260 may include and / or utilize several components similar to those described with reference to Figure 1. For example, system 260 may include polymer dissolution vessels 204A, 204B including inputs 206A, 206B, inputs 208A, 208B, and discharges 210A, 210B, filtration vessels 212A, 212B including discharges 214A, 214B and 216A, 216B, sorption separation vessels 218A, 218B including discharges 220A, 220B and 222A, 222B, extraction vessels 224A, 224B including discharges 226A, 226B and 228A, 228B, and polymer concentration vessels 230A, 230B including discharges 232A, 232B and 234A, 234B.

[0078] As shown in Fig. 2, the system 260 can include two of the systems 102 shown in Fig. 1 in parallel, and can utilize the discharge from the filtration vessel 212A as the input to the dissolution vessel 204B. As an example, a first recycled polymer, such as polyethylene, can be selectively dissolved in the dissolution vessel 204A and purified by a filtration step, such as using the filtration vessel 2121A, a sorption separation step, such as using the sorption separation vessel 218A, and an extraction step, such as using the extraction vessel 224A, in the first example of the disclosed method, and insoluble impurities, including a second recycled polymer, such as polypropylene (undissolved polymer from the dissolution vessel 204A), are removed as solids from the filtration vessel 212A. This solids stream containing the second regenerated polymer can then be used as feedstock to a second example of the disclosed method, where the polypropylene is selectively dissolved at different temperatures, pressures, and / or solvents in a second dissolution vessel 204B, for example utilizing dissolution vessel 204B, removed from undissolved impurities in a second filtration vessel 212B, and then purified from the dissolved impurities in a second sorption separation, for example utilizing sorption separation vessel 218B, and extraction, for example utilizing extraction vessel 224B. In principle, applying multiple examples of the disclosed method in parallel can be used to purify multiple different polymers present in the same regenerated polymer feedstock.

[0079] Some aspects of the present disclosure are provided as follows.

[0080] Aspect 1 provides a method for purifying a reclaimed polymer, the method comprising: transferring the reclaimed polymer to a polymer dissolution vessel, the reclaimed polymer comprising a solid; selectively dissolving the solid reclaimed polymer in the polymer dissolution vessel with a solvent to produce a polymer dissolution vessel composition, the polymer dissolution vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the polymer dissolution vessel composition to a filtration vessel to remove a first insoluble contaminant and produce a filtration vessel composition, the filtration vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the composition to a sorption separation vessel to remove the first soluble contaminant and produce a sorption separation vessel composition, the sorption separation vessel having a temperature of 70°C to 180°C and a pressure of 1 bar to 30 bar; transferring the sorption separation vessel composition to an extraction vessel to remove the first target portion of the solvent and the second soluble contaminant and produce an extraction vessel composition, the extraction vessel having a temperature of 130°C to 300°C and a pressure of 30 bar to 250 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove the second target portion of the solvent and the third soluble contaminant and produce a purified regenerated polymer.

[0081] Aspect 2 provides the method of aspect 1, wherein the recycled polymer is selected from polyethylene and polypropylene.

[0082] Aspect 3 provides a method according to aspect 1 and / or aspect 2, wherein the solvent comprises an alkane.

[0083] Aspect 4 provides a method according to aspect 1, aspect 2, and / or aspect 3, wherein the alkane solvent is selected from C5 to C7 alkanes.

[0084] Example 5 provides the method of example 1, example 2, example 3, and / or example 4, wherein the polymer dissolution vessel, the filtration vessel, and the sorption separation vessel each have temperatures within 20° C. of each other, and the polymer dissolution vessel, the filtration vessel, and the sorption separation each have pressures within 10 bar of each other.

[0085] Example 6 provides the method of example 1, example 2, example 3, example 4, and / or example 5, wherein the polymer concentrator vessel comprises one or more flash vessels.

[0086] Aspect 7 provides the method of aspect 1, aspect 2, aspect 3, aspect 4, aspect 5, and / or aspect 6, wherein the solvent has a boiling point between 25°C and 90°C.

[0087] Example 8 provides the method of example 1, example 2, example 3, example 4, example 5, example 6, and / or example 7, wherein the regenerated polymer is in the liquid phase in the filtration vessel and the sorption separation vessel.

[0088] Example 9 provides the method of example 1, example 2, example 3, example 4, example 5, example 6, example 7, and / or example 8, wherein the solvent is 80 to 95 weight percent based on the total weight of the solid reclaimed polymer and solvent transferred to the polymer dissolution vessel to create the polymer dissolution vessel composition.

[0089] Aspect 10 provides a method for purifying reclaimed polymer, the method including: transferring the reclaimed polymer to a polymer dissolution vessel, the reclaimed polymer including solids; selectively dissolving the solid reclaimed polymer in the polymer dissolution vessel with a solvent to create a polymer dissolution vessel composition, the polymer dissolution vessel having a temperature between 70° C. and 180° C. and a pressure between 1 bar and 30 bar; and transferring the polymer dissolution vessel composition to a filtration vessel to remove a first insoluble contaminant and a first soluble contaminant to create a filtration vessel composition. the filtration vessel composition having a temperature of 70°C to 180°C and a pressure of 1 bar to 30 bar; transferring the filtration vessel composition to an extraction vessel to remove the first target portion of the solvent and the second soluble contaminant to produce an extraction vessel composition, the extraction vessel having a temperature of 130°C to 300°C and a pressure of 30 bar to 250 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove the second target portion of the solvent and the third soluble contaminant to produce a purified regenerated polymer. EXAMPLES

[0090] Example 1 was carried out as follows. Aspen Plus V10 (obtained from Aspen Technology) was used to perform calculations of the method for purifying recycled polymers. For the calculations, polymers (polyethylene and polypropylene), solvent (n-pentane), and contaminants (calcium carbonate (2% by weight in the polymer), limonene (100 ppm), butylated hydroxytoluene (100 ppm), 1-decanal (100 ppm), dibutyl-o-phthalate (100 ppm), and bisphenol A (100 ppm) were used.

[0091] The calculations utilized the PC-SAFT (Perturbed Chain Statistical Associating Fluid Theory) equation of state model. Several monomial parameters were available in the Aspen Plus databank (e.g., for polyethylene, polypropylene, and several solvents). For monomial parameters that were not available in the Aspen Plus databank, liquid density, liquid heat capacity, and liquid vapor pressure data available from the TDE NIST databank (Thermo Data Engine, National Institute of Standards and Technology) were regressed. Binary interaction parameters were calibrated using publicly available mixture data.

[0092] For the calculations, recycled polyethylene (e.g., corresponding to input 106 as discussed herein and referred to as Computational Stream (CS) 106) was fed into a dissolution vessel (e.g., as discussed herein) along with pentane (e.g., corresponding to input 108 as discussed herein and referred to as CS108). Polyethylene was selectively dissolved over polypropylene in pentane at 20 bar and 110° C. The discharge from the dissolution vessel was passed through subsequent filtration and sorption separation steps (e.g., as discussed herein) to remove undissolved polypropylene and calcium carbonate to obtain CS122 (e.g., corresponding to discharge 122 as discussed herein). Calculations determined that 95% of the insoluble components, such as polypropylene and calcium carbonate, were removed. CS122 was further pressurized (to 100 bar) and heated (to 225° C.) before entering a one-stage extraction vessel (e.g., as discussed herein). In this step, non-volatile contaminants were removed better than by devolatilization alone. From the extract, the solvent-rich light phase was washed and recycled back, and the polymer-rich heavy phase was passed through additional devolatilization (e.g., to a polymer concentration vessel as discussed herein). From the devolatilization, the solvent vapor was recovered, the contaminants were removed, and the washed solvent was recycled. A final devolatilization step was performed at 20 mbara and 250° C. Then, for CS134 (e.g., corresponding to Effluent 134 as discussed herein), it was shown that 99% by weight of limonene and decanal, 90% by weight of butylated hydroxytoluene and dibutyl-o-phthalate, and 50% by weight of bisphenol A were removed. Some calculated stream conditions and components are shown in Table 1.

[0093] [Table 1]

[0094] The data in Table 1 shows that the reclaimed polymer is purified. The data in Table 1 shows improved contaminant removal efficiency compared to other polymer purification processes. Example 1 utilized solid polymer, and Example 1 provided a purified reclaimed polymer with improved, e.g., lower amounts of residual solvent, compared to other polymer purification processes.

[0095] Example 2 was carried out as follows: 1.0344 g of polyethylene (Dowlex 2045G) and 1.0317 g of polypropylene (Braskem D115a) were added to 8.28 g of n-pentane (Acros Organics, 99+%, extra pure, anhydrous) in an empty pressure cell (Anton Paar, 150 bar, stainless steel, max. temperature = 300°C). The number of polypropylene pellets added to the cell was counted to be 54. The cell was closed with a starch stirrer measuring geometry (Anton Paar, ST24 / PRA1) attached to the header. The closed cell was transferred to a rheometer (Anton Paar MCR 102) equipped with an electronic heater (Anton Paar, C-ETD300). The top outlet port of the cell was connected to a high pressure nitrogen gas source (Airgas, UHP grade) and the gas pressure was controlled by a regulator. The measuring cup on the rheometer was lowered into position above the cell, allowing controlled rotation of the stirrer feature within the cell using a magnetic coupling.

[0096] The cell was pressurized to 16 a bar with nitrogen gas added to the cell headspace. Using Rheocompass software (Anton Paar, V1.20.493), the stirrer was set to rotate at 400 rpm and the cell was heated to 110° C. The temperature was controlled by a thermocouple in the heater and monitored by an independent thermocouple in the cell wall. The temperature in the cell wall reached 110° C. after 15 minutes and did not exceed 111° C. for Example 2. The cell remained at the set points of 110° C. and 400 rpm for 6 hours, measured from the start of stirring at room temperature.

[0097] After this was maintained at the set point, the stirring was stopped and the cell was cooled to about 20° C. The pressurized nitrogen gas in the headspace was vented to atmospheric pressure and the cell was isolated and removed from the rheometer. The cell was opened and the material, observed to be a white paste with undissolved pellets entrapped therein, was recovered. The undissolved pellets were separated from the white paste, counted, and determined to be equal to the number of polypropylene pellets (54) added at the start of Example 2. The white paste, representing the polymer that dissolved during Example 2 and then recrystallized upon cooling, was analyzed using differential scanning calorimetry (DSC) to determine the relative amounts of polyethylene and polypropylene, a procedure that infers the amount of each that dissolved during Example 2.

[0098] DSC measurements were performed using a TA Instruments Discovery 2500 Differential Scanning Calorimeter. First, the white paste (approximately 0.5 g) was compressed into a film at 25000 psi and 190°C for 10-15 seconds. The compressed paste (3.7 mg) was weighed and placed into a DSC pan. A lid was crimped onto the pan to ensure a closed atmosphere, and the pan was placed into the DSC cell. The contents of the DSC pan were heated to 190°C at a rate of 10°C / min and held isothermal for 5 minutes. The contents of the DSC were then cooled to -40°C at a rate of 10°C / min and held isothermal for 5 minutes. The contents of the DSC were then heated to 230°C at a rate of 10°C / min and held isothermal for 5 minutes. During the heating and cooling ramps, data acquisition was turned on and heat flow was measured along with temperature. The melting peak (Tm), crystallization peak (Tc), melting heat of fusion (ΔHfm), crystallization heat of fusion (ΔHfc), and glass transition temperature (Tg) of the polymer samples were processed using TA Instrument Universal Analysis software. Polyethylene and propylene concentrations were determined by integrating the areas of the peaks corresponding to polyethylene (119.3 and 122.2 °C) and polypropylene (169.4 °C) in a plot of heat flow versus temperature during a temperature gradient from -40 to 230 °C. The relative area of ​​the polypropylene peak of the blend above 140 °C to the reference peak of pure polypropylene (93.2 J / g) gives a measure of the relative weight percent of polypropylene in the polymer blend. This indicated that 2.5 wt% of the white paste dissolved in the pressure cell was polypropylene for 97.5 wt% polyethylene. The results for dissolution at 110 °C are shown in Table 2.

[0099] [Table 2]

[0100] The data in Table 2 show that a mixture of polyethylene and polypropylene (50:50 wt%) was separated by selectively dissolving the polymers in n-pentane at 110° C. The data in Table 2 show that over 97 wt% of the polypropylene was removed.

Claims

1. 1. A method for purifying regenerated polymer, comprising: transferring the reclaimed polymer to a polymer dissolution vessel, the reclaimed polymer including solids; Selectively dissolving the solid regenerated polymer in the polymer dissolution vessel with a solvent to produce a polymer dissolution vessel composition, the polymer dissolution vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the polymer dissolution vessel composition to a filtration vessel to remove a first insoluble contaminant and produce a filtration vessel composition, the filtration vessel having a temperature of from 70° C. to 180° C. and a pressure of from 1 bar to 30 bar; transferring the filtration vessel composition to a sorption separation vessel to remove a first soluble contaminant and produce a sorption separation vessel composition, the sorption separation vessel having a temperature of from 70° C. to 180° C. and a pressure of from 1 bar to 30 bar; transferring the sorption separation vessel composition to an extraction vessel to remove the first target portion of the solvent and a second soluble contaminant to produce an extraction vessel composition, the extraction vessel having a temperature of 130° C. to 300° C. and a pressure of 30 bar to 250 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove a second target portion of the solvent and a third soluble contaminant to produce a purified regenerated polymer.

2. 2. The method of claim 1, wherein the recycled polymer is selected from polyethylene and polypropylene.

3. The method of claim 1 , wherein the solvent comprises an alkane.

4. 4. The method of claim 3, wherein the alkane solvent is selected from a C5 to C7 alkane.

5. 2. The method of claim 1, wherein the polymer dissolution vessel, the filtration vessel, and the sorption separation vessel each have temperatures within 20° C. of each other, and the polymer dissolution vessel, the filtration vessel, and the sorption separation vessel each have pressures within 10 bar of each other.

6. The method of claim 1 , wherein the polymer concentrator vessel comprises one or more flash vessels.

7. The method of claim 1, wherein the solvent has a boiling point of from 25°C to 90°C.

8. 10. The method of claim 1, wherein the regenerated polymer is in the liquid phase in the filtration vessel and the sorption separation vessel.

9. 2. The method of claim 1, wherein the solvent is 80 to 95 weight percent based on the total weight of the solid reclaimed polymer and the solvent transferred to the polymer dissolution vessel to create the polymer dissolution vessel composition.

10. 1. A method for purifying regenerated polymer, comprising: transferring the reclaimed polymer to a polymer dissolution vessel, the reclaimed polymer including solids; Selectively dissolving the solid regenerated polymer in the polymer dissolution vessel with a solvent to produce a polymer dissolution vessel composition, the polymer dissolution vessel having a temperature of 70° C. to 180° C. and a pressure of 1 bar to 30 bar; transferring the polymer dissolution vessel composition to a filtration vessel to remove a first insoluble contaminant and a first soluble contaminant to produce a filtration vessel composition, the filtration vessel having a temperature of from 70° C. to 180° C. and a pressure of from 1 bar to 30 bar; transferring the filtration vessel composition to an extraction vessel to remove the first target portion of the solvent and a second soluble contaminant to produce an extraction vessel composition, the extraction vessel having a temperature of 130° C. to 300° C. and a pressure of 30 bar to 250 bar; and transferring the extraction vessel composition to a polymer concentration vessel to remove a second target portion of the solvent and a third soluble contaminant to produce a purified regenerated polymer.

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