CN110072927A - Method for purifying regenerated polymer - Google Patents

Abstract

The present invention provides a method for purifying regenerated polymers. The method includes obtaining a regenerated polymer; contacting the regenerated polymer with a first fluid solvent to produce an extracted regenerated polymer; then dissolving the extracted regenerated polymer in the solvent to produce a polymer comprising the polymer and suspended contaminants the first solution. The first solution is allowed to settle to produce a second solution comprising polymer and remaining contaminants. The second solution is purified by contacting the second solution with a solid medium to produce a third solution comprising a purer polymer. Ultimately, the purer polymer is isolated from the third solution.

Description

Method for purifying regenerated polymers

technical field

The present invention generally relates to a method for purifying contaminated polymers through the use of pressurized solvents and solid media. More particularly, the present invention relates to a method for purifying recycled polymers, such as post-consumer and post-industrial recycled plastics, to produce virgin polymers that are colorless or clear and odorless. This method is particularly useful for the purification of polyolefins such as polyethylene and polypropylene.

Background technique

Polymers, especially synthetic plastics, are ubiquitous in everyday life due to their relatively low production costs and well-balanced material properties. Synthetic plastics are used in a wide variety of applications such as packaging, automotive components, medical devices, and consumer products. To meet the high demands of these applications, tens of billions of pounds of synthetic plastic are produced globally each year. The vast majority of synthetic plastics are produced from increasingly scarce fossil resources such as oil and natural gas. In addition, the manufacture of synthetic plastics from fossil resources produces _CO2 as a by-product.

The widespread use of synthetic plastics thus results in the generation of millions of tons of plastic waste every year. While most plastic waste is landfilled via municipal solid waste programs, most plastic waste is found in the environment as litter, which is unsightly and potentially harmful to the ecosystem. Plastic waste is often washed into river systems and ends up at sea.

Plastic recycling has emerged as a solution to the problems associated with the widespread use of plastics. Recycling and reusing plastics diverts waste from landfills and reduces the demand for virgin plastics made from fossil resources, thereby reducing greenhouse gas emissions. In developed regions, such as the United States and the European Union, plastic recycling rates are on the rise due to increased awareness among consumers, businesses and industrial manufacturing. Most recycled materials, including plastics, are mixed into a single stream, which is collected and processed by a material recovery facility (MRF). At MRF, material is sorted, washed and packaged for resale. Plastics can be divided into individual materials such as high density polyethylene (HDPE) or poly(ethylene terephthalate) (PET), or mixed streams of other common plastics such as polypropylene (PP), low density polyethylene Ethylene (LDPE), poly(vinyl chloride) (PVC), polystyrene (PS), polycarbonate (PC) and polyamide (PA). The single stream or mixed stream can then be further classified, washed and reprocessed into pellets suitable for reuse in plastics processing such as blow molding and injection molding.

Although recycled plastics are sorted into predominantly homogeneous streams and washed with aqueous and/or caustic solutions, the final reprocessed pellets typically remain free from unwanted waste impurities such as spoiled food scraps and residual flavor components Highly polluted. In addition, recycled plastic pellets other than those from recycled beverage containers are dark due to the mixture of dyes and pigments commonly used to color plastic articles. While there are some applications that are not sensitive to color and contamination (such as black plastic paint containers and hidden motor vehicle parts), most applications require colorless pellets. The need for high quality "raw" recycled resins is especially important for food and pharmaceutical contact applications such as food packaging. In addition to contamination with impurities and mixed colorants, many recycled resin products are often heterogeneous in chemical composition and may contain significant amounts of polymer contaminants, such as polyethylene (PE) in recycled PP ) pollutants and PP pollutants in recycled polyethylene (PE).

Mechanical recycling, also known as secondary recycling, is a method of converting recycled plastic waste into a reusable form for subsequent manufacturing. A more detailed review of mechanical recycling and other plastic recycling methods is described in S.M.Al-Salem, P. Lettieri, J. Baeyens, "Recycling and recovery routes of plastic solid waste (PSW): A review", Waste Management, Volume 29, Issue 10, October 2009, Pages 2625-2643, ISSN0956-053X (S.M.Al-Salem, P.Letieri, J.Baeyens, "Recycling and Recovery Routes for Solid Plastic Waste: A Review", Waste Management, pp. 29 Vol. 10, October 2009, pp. 2625-2643, ISSN 0956-053X). Although advances in mechanical recycling technology have improved the quality of recycled polymers to some extent, there are still fundamental limitations to mechanical purification methods, such as physical entrapment of pigments within the polymer matrix. Thus, even as mechanical recycling techniques improve, the dark color and high levels of chemical contamination in currently available recycled plastic waste prevent widespread use of recycled resins by the plastics industry.

To overcome the fundamental limitations of mechanical recycling, a number of methods have been developed to purify contaminated polymers via chemical methods or chemical recycling. Most of these methods use solvents to purify and purify polymers. The use of solvents enables extraction of impurities and dissolution of polymers, which further enables alternative separation techniques.

For example, US Patent 7,935,736 describes a method for recycling polyester from polyester-containing waste using a solvent to dissolve the polyester prior to cleaning. The '736 patent also describes the need to recover polyesters from solvents using precipitants.

In another example, US Patent 6,555,588 describes a method of producing polypropylene blends from plastic mixtures containing other polymers. The '588 patent describes the extraction of contaminants from a polymer for a specified residence time period at a temperature below the dissolution temperature of the polymer in a selected solvent, such as hexane. The '588 patent also describes increasing the temperature of the solvent (or second solvent) to dissolve the polymer prior to filtration. The '588 patent also describes the use of shear or flow to precipitate polypropylene from solution. The polypropylene blends described in the '588 patent contain up to 5.6 weight percent polyethylene contamination.

In another example, European Patent Application 849,312 (translated from German to English) describes a process for obtaining purified polyolefins from polyolefin-containing plastic mixtures or polyolefin-containing wastes. The '312 patent application describes the extraction of polyolefin mixtures or wastes with hydrocarbon fractions of gasoline or diesel fuels boiling above 90°C at temperatures between 90°C and the boiling point of the hydrocarbon solvent. The '312 patent application also describes contacting a hot polyolefin solution with bleaching clay and/or activated carbon to remove foreign components from the solution. The '312 patent also describes cooling the solution to a temperature below 70°C to crystallize the polyolefin, and then by heating the polyolefin above the melting point of the polyolefin, either by evaporating the adhesion solvent in a vacuum or by passing a gas stream through the polyolefin. Precipitation of the olefin, and/or extraction of solvent with alcohol or ketone boiling below the melting point of the polyolefin to remove the sticking solvent.

In another example, US Pat. No. 5,198,471 describes a method for separating polymers from a physically mixed solid mixture (eg, waste plastic) containing a plurality of polymers using a solvent at a first lower temperature to form a first monomer Method for phase solutions and residual solid components. The '471 patent also describes heating the solvent to a higher temperature to dissolve additional polymers that would not dissolve at the first lower temperature. The '471 patent describes the filtration of undissolved components.

In another example, US Pat. No. 5,233,021 describes a method for extracting pure polymer components from a multi-component structure, such as waste carpet, by dissolving each component in a supercritical fluid at the appropriate temperature and pressure and then changing the temperature and/or pressure to sequentially extract specific components. However, like the '471 patent, the '021 patent only describes the filtration of the precipitated components.

In another example, US Pat. No. 5,739,270 describes a method and apparatus for continuously separating polymer components of plastics from contaminants and other components of plastics using co-solvents and working fluids. The co-solvent at least partially dissolves the polymer, and the second fluid (ie, in a liquid, critical or supercritical state) dissolves components from the polymer and precipitates some of the dissolved polymer from the co-solvent. The '270 patent also describes the step of filtering a thermoplastic co-solvent (with or without a working fluid) to remove particulate contaminants such as glass particles.

As noted above, known solvent-based methods for purifying contaminated polymers do not produce "native" polymers. In previous methods, co-dissolution of other polymers and thus cross-contamination often occurred. If an adsorbent is used, filtration and/or centrifugation steps are typically employed to remove the adsorbent used from the solution. In addition, separation processes to remove solvent such as heating, vacuum evaporation and/or precipitation using precipitation chemicals are used to produce polymers free of residual solvent.

Therefore, there remains a need for an improved solvent-based method for purifying contaminated polymers using a solvent that can be easily and economically removed from the polymer, is relatively simple in terms of number of operations, and does not result in large quantities of polymer Polymers are produced with cross-contamination, substantially colorless polymers are produced, and substantially odorless polymers are produced.

SUMMARY OF THE INVENTION

A method for purifying a regenerated polymer is provided. The method includes:

a. obtaining a recycled polymer selected from the group consisting of post-consumer polymers, post-industrial polymers, and combinations thereof;

b. contacting the regenerated polymer with a first fluid solvent having a normal boiling point of less than about 70°C at a temperature of about 80°C to about 220°C and a pressure of about 150 psig (1.03 MPa) to about 15,000 psig (103.42 MPa), to producing an extracted recycled polymer;

c. Dissolving the extracted regenerated polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, a and their mixtures in a solvent to produce a first solution comprising the polymer and suspended contaminants;

d. Settling the first solution comprising the polymer and suspended contaminants at a temperature of about 90°C to about 220°C and a pressure of about 350 psig (2.41 MPa) to about 20,000 psig (137.90 MPa) to produce a polymer comprising the remaining a second solution of contaminants;

e. Purify the second solution by contacting the second solution with the solid medium at a temperature of about 90°C to about 220°C and a pressure of about 350 psig (2.41 MPa) to about 20,000 psig (137.90 MPa) to produce a more pure a third solution of the polymer; and

f. Isolate the purer polymer from the third solution.

The second fluid solvent may have the same chemical composition as the first fluid solvent or a different chemical composition.

In one embodiment, the purer polymer is isolated from the third solution at a temperature of about 0°C to about 220°C and a pressure of about 0 psig (0 MPa) to 2,000 psig (13.79 MPa). In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 0.5%. In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 1%. In one embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 2%.

In one embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 3%. In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 4%. In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of at least 5% by mass.

In one embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of up to 20% by mass. In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of up to 18% by mass. In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of up to 16% by mass. In one embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of up to 14%. In another embodiment, the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of up to 12% by mass.

In one embodiment, the recycled polymer is a polymer derived from post-consumer recycling. In another embodiment, the recycled polymer is polystyrene. In another embodiment, the polymer is poly(dimethylsiloxane). In another embodiment, the recycled polymer is a polypropylene homopolymer or is a primary polypropylene copolymer. In another embodiment, the recycled polymer is a polyethylene homopolymer or is a primary polyethylene copolymer. In another embodiment, the fluid solvent has a normal boiling point of less than about 0°C and greater than about -45°C and a normalized enthalpy change of vaporization of less than about +25 kJ/mol.

In one embodiment, the fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof. In another embodiment, the aliphatic hydrocarbon is selected from the group consisting of _C1 - _C6 aliphatic hydrocarbons and mixtures thereof. In another embodiment, the aliphatic hydrocarbons and mixtures thereof consist of predominantly _C4 aliphatic hydrocarbons.

In another embodiment, the fluid solvent consists essentially of _C4 liquefied petroleum gas. In one embodiment, the fluid solvent is n-butane, butane isomers, or mixtures thereof. In another embodiment, the temperature in the contacting, dissolving, settling and purification steps is from about 110°C to about 170°C.

In one embodiment, the pressure in the contacting step is from about 1,100 psig (7.58 MPa) to about 5,500 psig (37.92 MPa). In another embodiment, the pressure in the contacting step is less than about 1,100 psig (7.58 MPa). In another embodiment, the pressure in the dissolution, settling and purification steps is greater than about 1,100 psig (7.58 MPa). In one embodiment, the pressure during the dissolution, settling and purification steps is greater than about 5,500 psig (37.92 MPa).

In one embodiment, the solid medium is selected from inorganic substances, carbon-based substances, and mixtures thereof. In another embodiment, the inorganic species is selected from the group consisting of oxides of silicon, oxides of aluminum, oxides of iron, aluminum silicates, amorphous volcanic glasses, and mixtures thereof. In another embodiment, the inorganic material is selected from the group consisting of silica, silica gel, diatomaceous earth, sand, quartz, alumina, perlite, fuller's earth, bentonite, and mixtures thereof.

In one embodiment, the carbon-based material is selected from the group consisting of anthracite, carbon black, coke, activated carbon, cellulose, and mixtures thereof. In another embodiment, the contacting of the polymer solution with the solid medium is carried out in a packed bed of the solid medium. In another embodiment, the length of the packed bed is greater than 20 cm.

Additional features of the present invention may become apparent to those skilled in the art from reading the following detailed description in conjunction with the examples.

Description of drawings

Figure 1 is a block flow diagram illustrating the main steps of one embodiment of the present invention.

Figure 2 is a calibration curve for calculating polyethylene content in polypropylene using enthalpy values from DSC measurements.

3A is a schematic diagram of the experimental setup used in the extraction steps of Examples 2 and 3. FIG.

3B is a schematic diagram of the experimental setup used in the dissolution and precipitation steps of Examples 2 and 3. FIG.

Figure 4 is a photograph of an exemplary sample.

Detailed ways

I. Definitions

As used herein, the term "recycled polymer" refers to a polymer that is used for a previous purpose and then recovered for further processing.

As used herein, the term "post-consumer" refers to the source of a material that is produced after the final consumer uses the material in a consumer product or product.

As used herein, the term "post-consumer recycling" (PCR) refers to material that is produced after the material has been used by the end consumer and placed in a waste stream.

As used herein, the term "post-industrial" refers to the source of materials produced during the manufacture of a commodity or product.

As used herein, the term "fluid solvent" refers to a substance that can exist in a liquid state under specified conditions of temperature and pressure. In some embodiments, the fluid solvent may be a predominantly homogeneous chemical composition of one molecule or isomer, while in other embodiments, the fluid solvent may be a mixture of several different molecular compositions or isomers. In addition, in some embodiments of the present invention, the term "fluid solvent" may also apply to being at, near, or above the critical temperature and pressure of the substance (critical point) The critical temperature and critical pressure (critical point) of the substance for the substance. It is well known to those of ordinary skill in the art that substances above the critical point of the substance are referred to as "supercritical fluids", which do not possess the typical physical properties (ie density) of liquids.

As used herein, the term "dissolving" refers to the at least partial incorporation of a solute (polymer or non-polymer) into a solvent at the molecular level. Furthermore, the thermodynamic stability of the solute/solvent solution can be described by the following Equation 1:

Formula 1

ΔG _mix =ΔH _m -TΔS _mix

where ΔG _mix is the Gibbs free energy change of solute-solvent mixing, ΔH _mix is the enthalpy change of mixing, T is the absolute temperature, and ΔS _mix is the entropy of mixing. To maintain a stable solution of a solute in a solvent, the Gibbs free energy must be negative and minimal. Thus, any combination of solutes and solvents that minimizes the negative Gibbs free energy at appropriate temperature and pressure can be used in the present invention.

As used herein, the term "normal boiling point" refers to the boiling temperature at exactly 100 kPa (1 bar, 14.5 psia, 0.9869 atm) absolute pressure as established by the International Union of Pure and Applied Chemistry (IUPAC).

As used herein, the term "standard vaporization enthalpy change" refers to the enthalpy change required to convert a specified amount of a substance from a liquid to a vapor at the normal boiling point of the substance.

As used herein, the term "polymer solution" refers to a solution of a polymer dissolved in a solvent. A polymer solution may contain undissolved material, and thus a polymer solution may also be a "slurry" of undissolved material suspended in a solution of polymer dissolved in a solvent.

As used herein, the terms "precipitation" and "settling" refer to the tendency of particles in a suspension to separate from a liquid in response to a force (usually gravity) acting on the particles.

As used herein, the term "suspended contaminants" refers to unwanted or undesired components present throughout the bulk of the medium of a heterogeneous mixture.

As used herein, the term "solid medium" refers to a substance that exists in a solid state under the conditions of use. The solid medium may be crystalline, semi-crystalline or amorphous. The solid medium can be granular and can be supplied in different shapes (ie spheres, cylinders, pellets, etc.). If the solid medium is particulate, the particle size and particle size distribution of the solid medium can be defined by the mesh size used to classify the particulate medium. Examples of standard mesh size designations can be found in the American Society for Testing and Materials (ASTM) Standard ASTM E11 "Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves". The solid medium can also be a nonwoven fiber mat or a woven textile.

As used herein, the term "more pure polymer solution" refers to a polymer solution with fewer contaminants relative to the same polymer solution prior to the purification step.

As used herein, the term "extraction" refers to the practice of transferring solute species from a liquid phase (or solid matrix) across a phase boundary to a separate immiscible liquid phase. One or more driving forces for extraction are described by distribution theory.

As used herein, the term "extracted" refers to a material that has less solute species relative to the same material prior to the extraction step. As used herein, the term "extracted regenerated polymer" refers to a regenerated polymer that has less solute species relative to the same regenerated polymer prior to the extraction step.

As used herein, the term "native" means substantially free of contaminants, pigment-free, odorless, homogeneous, and similar in properties to virgin polymers.

As used herein, the term "primary polypropylene copolymer" refers to a copolymer having greater than 70 mol% of propylene repeating units.

As used herein, the term "primary polyethylene copolymer" refers to a copolymer having greater than 70 mole percent ethylene repeating units.

As used herein, any reference to an SI unit of pressure (eg, MPa) refers to gauge pressure.

II. Methods for Purification of Contaminated Polymers

Surprisingly, it has been found that certain fluid solvents, which in preferred embodiments exhibit temperature and pressure dependent solubility for polymers, can be used to purify contaminated polymers when used in a relatively simple process, Especially regenerated or recycled polymers in near-virgin quality. The method is illustrated in Figure 1 and comprises: 1) obtaining a regenerated polymer (step a in Figure 1), then 2) extracting the polymer with a fluid solvent at extraction temperature ( _TE ) and extraction pressure ( _PE ) ( Step b) in Figure 1, then 3) dissolving the polymer in a fluid solvent at the dissolution temperature (T _D ) and dissolution pressure (P _D ) (step c in Figure 1 ), then 4) at the dissolution temperature ( The polymer solution is precipitated at T _D ) and dissolution pressure (P _D ) (step d in FIG. 1 ), then 5) the dissolved polymer solution is allowed to react with dissolution temperature (T _D ) and dissolution pressure (P _D ) at dissolution temperature (T D ) and dissolution pressure (P D ). The solid medium is contacted (step e in FIG. 1 ) and then the polymer is separated from the fluid solvent (step f in FIG. 1 ).

In one embodiment of the present invention, purified polymers that may be derived from post-consumer waste streams are substantially free of contaminants, pigment-free, odorless, homogeneous and similar in properties to virgin polymers. Furthermore, in a preferred embodiment, the physical properties of the fluid solvents of the present invention enable more energy efficient methods for separating fluid solvents from purified polymers.

recycled polymer

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises obtaining a regenerated polymer. For the purposes of the present invention, recycled polymers are derived from post-consumer, post-industrial, post-commercial and/or other special waste streams. For example, post-consumer waste polymers can be sourced from curbside recycling streams, where end consumers place used polymers from packaging and products into designated bins for collection by waste haulers or recyclers . Post-consumer waste polymer can also be sourced from in-store "recycle" programs, where consumers bring waste polymer into the store and place the waste polymer in designated collection bins. An example of a post-industrial waste polymer may be waste polymer produced during the manufacture or transport of commodities or products collected by the manufacturer as unusable material (ie trim waste, out of specification material, start-up waste). An example of waste polymer from a special waste stream may be waste polymer derived from the recycling of electronic waste (also referred to as "e-waste"). Another example of waste polymer from special waste streams may be recycled waste polymer from automobiles. Another example of waste polymer from special waste streams may be recycled waste polymer from used carpets and textiles.

For the purposes of the present invention, a recycled polymer is a homogeneous composition of a single polymer or a mixture of several different polymer compositions. Non-limiting examples of recycled polymer compositions are homopolymers and copolymers of: polyolefins, such as polyethylene and isotactic polypropylene; polyesters, such as poly(ethylene terephthalate); vinyl polymers such as poly(vinyl chloride); styrene polymers such as polystyrene; polyamides such as poly(hexamethylene adipamide); polycarbonates such as poly(bisphenol A carbonate); Polyacrylates, such as poly(methyl methacrylate); polysiloxanes, such as poly(dimethylsiloxane); thermoplastic elastomers, such as styrene-butadiene block copolymers and ethylene-propylene rubbers ; and other soluble polymers that may be apparent to those of ordinary skill in the art.

Recycled polymers may also contain various pigments, dyes, processing aids, stabilizing additives, fillers, and other performance additives that are added to the polymer during polymerization or conversion of the virgin polymer into the final article form. Non-limiting examples of pigments are organic pigments such as copper phthalocyanine, inorganic pigments such as titanium dioxide, and others that may be apparent to those of ordinary skill in the art. A non-limiting example of an organic dye is Basic Yellow 51. Non-limiting examples of processing aids are antistatic agents such as glycerol monostearate and slip agents such as erucamide. A non-limiting example of a stabilizing additive is octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate. Non-limiting examples of fillers are calcium carbonate, talc, and glass fibers.

solvent

The fluid solvent of the present invention has a normal boiling point of less than about 70°C. Pressurization maintains a solvent having a normal boiling point below the operating temperature range of the present invention in a state with little or no solvent vapor. In one embodiment, the fluid solvent having a normal boiling point of less than about 70°C is selected from the group consisting of carbon dioxide, ketones, alcohols, ethers, esters, olefins, alkanes, and mixtures thereof. Non-limiting examples of fluid solvents with normal boiling points less than about 70°C are carbon dioxide, acetone, methanol, dimethyl ether, diethyl ether, ethyl methyl ether, tetrahydrofuran, methyl acetate, ethylene, propylene, 1-butene , 2-butene, isobutene, 1-pentene, 2-pentene, branched isomers of pentene, 1-hexene, 2-hexene, methane, ethane, propane, n-butane, isobutene alkane, n-pentane, isopentane, neopentane, n-hexane, isomers of isohexane, and others that may be apparent to those of ordinary skill in the art.

The selection of the appropriate solvent or solvent mixture will depend on which regenerated polymer or polymer mixture is being purified by the present invention. Furthermore, the choice of polymer to be purified and the corresponding fluid solvent used will dictate the temperature and pressure ranges used to carry out the steps of the present invention. An overview of the phase properties of polymers in solvents of the type described in the present invention is provided in the following reference: McHugh et al. (1999) Chem. Rev. 99:565-602.

extract

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting the regenerated polymer with a fluid solvent at a temperature and pressure, wherein the polymer is substantially insoluble in the fluid solvent. While not wishing to be bound by any theory, applicants believe that the temperature and pressure-dependent solubility can be controlled in such a way that the fluid solvent prevents complete dissolution of the polymer, however, the fluid solvent can diffuse into the polymer and extract any extractable pollutants. Extractable contaminants may be residual processing aids added to the polymer, residual product formulations that contact the polymer such as fragrances and flavors, dyes, and may have been intentionally added or otherwise added, for example, during waste collection and subsequent accumulation of other waste. Any other extractable material that is not intended to be incorporated into the polymer.

In one embodiment, controlled extraction can be accomplished by fixing the temperature of the polymer/fluid solvent system, and then controlling the pressure below the pressure or pressure range where the polymer is dissolved in the fluid solvent. In another embodiment, controlled extraction is accomplished by fixing the pressure of the polymer/solvent system, and then controlling the temperature below the temperature or temperature range where the polymer dissolves in the fluid solvent. Temperature- and pressure-controlled extraction of polymers with fluid solvents uses suitable pressure vessels and can be constructed in a manner that allows for continuous extraction of polymers with fluid solvents. In one embodiment of the invention, the pressure vessel may be a continuous liquid-liquid extraction column, wherein the molten polymer is pumped into one end of the extraction column and the fluid solvent is pumped into the same or opposite end of the extraction column. In another embodiment, the fluid containing the extracted contaminants is removed from the process. In another embodiment, the fluid containing the extracted contaminants is purified, recovered and recycled for use in the extraction step or a different step in the process. In one embodiment of the present invention, the extraction can be performed in a batch process wherein the regenerated polymer is immobilized in a pressure vessel and the fluid solvent is continuously pumped through the immobilized polymer phase. The extraction time or amount of fluid solvent used will depend on the desired purity of the final purer polymer and the amount of extractable contaminants in the starting regenerated polymer. In another embodiment, the fluid containing the extracted contaminants is contacted with a solid medium as in a separate step as described in the "Purification" section below. In another embodiment, a method for purifying a regenerated polymer comprises contacting the regenerated polymer with a fluid solvent at a temperature and pressure, wherein the polymer is molten and in a liquid state. In another embodiment, the regenerated polymer is contacted with a fluid solvent at a temperature and pressure wherein the polymer is in a solid state.

In one embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with a fluid solvent at a temperature and pressure, wherein the polyethylene remains substantially undissolved. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with n-butane at a temperature of about 80°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with n-butane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with n-butane at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with n-butane at a pressure of from about 150 psig (1.03 MPa) to about 6,500 psig (44.82 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting polyethylene with n-butane at a pressure of from about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with n-butane at a pressure of from about 4,500 psig (31.03 MPa) to about 5,500 psig (37.92 MPa).

In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with propane at a temperature of from about 80°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with propane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with propane at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with propane at a pressure of from about 1,000 psig (6.89 MPa) to about 15,000 psig (103.42 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with propane at a pressure of from about 2,000 psig (13.79 MPa) to about 10,000 psig (68.95 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polyethylene with propane at a pressure of from about 5,000 psig (34.47 MPa) to about 9,000 psig (62.05 MPa).

In one embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with a fluid solvent at a temperature and pressure, wherein the polypropylene remains substantially undissolved. In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with n-butane at a temperature of about 80°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with n-butane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with n-butane at a temperature of about 130°C to about 180°C. In another embodiment, the method for purifying the regenerated polymer comprises contacting polypropylene with n-butane at a pressure of from about 150 psig (1.03 MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 2,750 psig (18.96 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with n-butane at a pressure of from about 1,500 psig (10.34 MPa) to about 2,500 psig (17.24 MPa).

In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with propane at a temperature of from about 80°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with propane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with propane at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with propane at a pressure of from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with propane at a pressure of from about 1,000 psig (6.89 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polypropylene with propane at a pressure of from about 2,000 psig (13.79 MPa) to about 4,000 psig (27.58 MPa).

In one embodiment, a method for purifying a regenerated polymer includes contacting polystyrene with a fluid solvent at a temperature and pressure, wherein the polystyrene remains substantially undissolved. In another embodiment, a method for purifying a regenerated polymer comprises contacting polystyrene with n-butane at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes contacting polystyrene with n-butane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting polystyrene with n-butane at a temperature of from about 120°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes contacting polystyrene with n-butane at a pressure of from about 500 psig (3.45 MPa) to about 5,000 psig (34.47 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting polystyrene with n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 4,000 psig (27.58 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting polystyrene with n-butane at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa).

In one embodiment, a method for purifying a regenerated polymer comprises contacting poly(dimethylsiloxane) with a fluid solvent at a temperature and pressure, wherein the poly(dimethylsiloxane) remains substantially free dissolve. In another embodiment, a method for purifying a regenerated polymer comprises contacting the poly(dimethylsiloxane) with n-butane at a temperature of from about 100°C to about 220°C. In another embodiment, the method for purifying the regenerated polymer comprises contacting the poly(dimethylsiloxane) with n-butane at a temperature of from about 115°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes contacting the poly(dimethylsiloxane) with n-butane at a temperature of from about 120°C to about 180°C. In another embodiment, the method for purifying the regenerated polymer comprises contacting the poly(dimethylsiloxane) with n-butane at a pressure of from about 200 psig (1.38 MPa) to about 1,800 psig (12.41 MPa). In another embodiment, the method for purifying the regenerated polymer comprises contacting the poly(dimethylsiloxane) with n-butane at a pressure of from about 300 psig (2.07 MPa) to about 1,500 psig (10.34 MPa). In another embodiment, the method for purifying the regenerated polymer comprises contacting the poly(dimethylsiloxane) with n-butane at a pressure of from about 500 psig (3.45 MPa) to about 1,000 psig (6.89 MPa).

dissolve

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises dissolving the regenerated polymer in a fluid solvent at a temperature and pressure, wherein the polymer is dissolved in the fluid solvent. While not wishing to be bound by any theory, applicants believe that the temperature and pressure can be controlled in a manner that results in a thermodynamically favorable dissolution of the regenerated polymer in the fluid solvent. In addition, temperature and pressure can be controlled in a manner that enables the dissolution of a particular polymer or polymer mixture without dissolving other polymers or polymer mixtures. This controlled dissolution enables the separation of the polymer from the polymer mixture.

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises dissolving the contaminated regenerated polymer in a solvent that does not dissolve the contaminants under the same temperature and pressure conditions. Contaminants can include pigments, fillers, soils, and other polymers. These contaminants are released from the regenerated polymer upon dissolution and are then removed from the polymer solution via a subsequent solid-liquid separation step.

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises dissolving polyethylene in a fluid solvent at a temperature and pressure, wherein the polyethylene is dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 12,000 psig (82.74 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a pressure of from about 2,000 psig (13.79 MPa) to about 10,000 psig (68.95 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a pressure of from about 4,000 psig (27.58 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in n-butane at a mass percent concentration of at least 0.5%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 1%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes dissolving polyethylene in n-butane at a concentration of up to 20% by mass. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 12%.

In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a pressure of from about 3,000 psig (20.68 MPa) to about 20,000 psig (137.90 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a pressure of from about 5,000 psig (34.47 MPa) to about 15,000 psig (103.42 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a pressure of from about 8,000 psig (55.16 MPa) to about 11,000 psig (75.84 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polyethylene in propane at a mass percent concentration of at least 0.5%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 1%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes dissolving polyethylene in propane at a concentration of up to 20% by mass. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, the method for purifying the regenerated polymer comprises dissolving polypropylene in a fluid solvent at a temperature and pressure, wherein the polypropylene is dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in n-butane at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in n-butane at a temperature of from about 100°C to about 200°C. In another embodiment, the method for purifying the regenerated polymer comprises dissolving polypropylene in n-butane at a temperature of about 130°C to about 180°C. In another embodiment, the method for purifying the regenerated polymer comprises dissolving polypropylene in n-butane at a pressure of from about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In another embodiment, a method for purifying a regenerated polymer includes dissolving polypropylene in n-butane at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in n-butane at a concentration of at least 0.5% by mass. In another embodiment, the polypropylene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polypropylene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes dissolving polypropylene in n-butane at a concentration of up to 20% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 12%.

In another embodiment, the method for purifying the regenerated polymer comprises dissolving polypropylene in propane at a temperature of from about 90°C to about 220°C. In another embodiment, the method for purifying the regenerated polymer comprises dissolving polypropylene in propane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in propane at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes dissolving polypropylene in propane at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in propane at a pressure of from about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in propane at a pressure of from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polypropylene in propane at a concentration of at least 0.5% by mass. In another embodiment, the polypropylene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polypropylene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes dissolving polypropylene in propane at a concentration of up to 20% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer includes dissolving polystyrene in a fluid solvent at a temperature and pressure, wherein the polystyrene is dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polystyrene in n-butane at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes dissolving polystyrene in n-butane at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving polystyrene in n-butane at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes dissolving polystyrene in n-butane at a pressure of from about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In another embodiment, a method for purifying a regenerated polymer comprises dissolving polystyrene in n-butane at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer includes dissolving polystyrene in n-butane at a pressure of from about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa). In another embodiment, a method for purifying regenerated polystyrene includes dissolving polystyrene in n-butane at a mass percent concentration of at least 0.5%. In another embodiment, the polystyrene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polystyrene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying regenerated polystyrene includes dissolving polystyrene in n-butane at a concentration of up to 20% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polystyrene is dissolved at a concentration of up to 16% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer includes dissolving poly(dimethylsiloxane) in a fluid solvent at a temperature and pressure, wherein the poly(dimethylsiloxane) is dissolved in the fluid in solvent. In another embodiment, the method for purifying the regenerated polymer comprises dissolving the poly(dimethylsiloxane) in n-butane at a temperature of about 115°C to about 220°C. In another embodiment, the method for purifying the regenerated polymer comprises dissolving the poly(dimethylsiloxane) in n-butane at a temperature of from about 120°C to about 200°C. In another embodiment, the method for purifying the regenerated polymer comprises dissolving the poly(dimethylsiloxane) in n-butane at a temperature of from about 140°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises dissolving poly(dimethylsiloxane) in n-butane at a pressure of from about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa) . In another embodiment, a method for purifying a regenerated polymer comprises dissolving poly(dimethylsiloxane) in n-butane at a pressure of from about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa) . In another embodiment, a method for purifying a regenerated polymer comprises dissolving poly(dimethylsiloxane) in n-butane at a pressure of from about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa) . In another embodiment, a method for purifying a regenerated poly(dimethylsiloxane) comprises dissolving the poly(dimethylsiloxane) in n-butane at a concentration of at least 0.5% by mass. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying regenerated poly(dimethylsiloxane) includes dissolving the poly(dimethylsiloxane) in n-butane at a concentration of up to 20% by mass. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

precipitation

In one embodiment of the invention, a method for purifying a polymer comprises separating undissolved contaminants from a polymer solution via a precipitation (also known as settling) step at a temperature and pressure, wherein the polymer remains dissolved in in fluid solvent. In one embodiment, the settling step causes the undissolved contaminants to experience a force that uniformly moves the undissolved contaminants in the direction of the force. Typically the settling force applied is gravity, but could also be centrifugal, centripetal, or some other force. The amount of force applied and the duration of settling will depend on several parameters including, but not limited to, the particle size of the contaminant particles, the density of the contaminant particles, the density of the fluid or solution, and the viscosity of the fluid or solution. The following formula (Equation 2) is the relationship between the aforementioned parameters and settling velocity, which is a measure of the settling rate of pollutants:

Formula 2

where v is the settling velocity, ρ _p is the density of the pollutant particle, ρ _f is the density of the fluid or solution, g is the acceleration due to an applied force (usually gravity), r is the radius of the pollutant particle, and η is The dynamic viscosity of a fluid or solution. Some of the key parameters that determine solution viscosity are: the chemical composition of the fluid solvent, the molecular weight of the polymer dissolved in the fluid solvent, the concentration of the polymer dissolved in the fluid solvent, the temperature of the fluid solvent solution, and the temperature of the fluid solvent solution. pressure.

In one embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/fluid solvent solution at a temperature and pressure, wherein the polyethylene remains dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution at a pressure of from about 1,000 psig (6.89 MPa) to about 12,000 psig (82.74 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution at a pressure of from about 2,000 psig (13.79 MPa) to about 10,000 psig (68.95 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution at a pressure of from about 4,000 psig (27.58 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 1%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/n-butane solution, wherein the polyethylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 12%.

In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution at a pressure of from about 3,000 psig (20.68 MPa) to about 20,000 psig (137.90 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution at a pressure of from about 5,000 psig (34.47 MPa) to about 15,000 psig (103.42 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution at a pressure of from about 8,000 psig (55.16 MPa) to about 11,000 psig (75.84 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 1%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polyethylene/propane solution, wherein the polyethylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/fluid solvent solution at a temperature and pressure, wherein the polypropylene remains dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution at a pressure of from about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution at a pressure of from about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polypropylene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polypropylene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/n-butane solution, wherein the polypropylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 12%.

In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution at a pressure of from about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution at a pressure of from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polypropylene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polypropylene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polypropylene/propane solution, wherein the polypropylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/fluid solvent solution at a temperature and pressure, wherein the polystyrene remains dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution at a pressure of from about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution at a pressure of from about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa). In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution, wherein the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polystyrene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polystyrene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a polystyrene/n-butane solution, wherein the polystyrene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polystyrene is dissolved at a concentration of up to 16% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer includes settling contaminants from a poly(dimethylsiloxane)/fluid solvent solution at a temperature and pressure, wherein the poly(dimethylsiloxane) Remain dissolved in fluid solvent. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a poly(dimethylsiloxane)/n-butane solution at a temperature of from about 115°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a poly(dimethylsiloxane)/n-butane solution at a temperature of from about 120°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a poly(dimethylsiloxane)/n-butane solution at a temperature of from about 140°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises removing a poly(dimethylsiloxane)/n-butane solution at a pressure of from about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa) Fallout pollutants. In another embodiment, a method for purifying a regenerated polymer comprises removing a poly(dimethylsiloxane)/n-butane solution from a poly(dimethylsiloxane)/n-butane solution at a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). Fallout pollutants. In another embodiment, a method for purifying a regenerated polymer comprises converting from a poly(dimethylsiloxane)/n-butane solution and Settling pollutants in solid media. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a poly(dimethylsiloxane)/n-butane solution, wherein the poly(dimethylsiloxane) is treated at a concentration of at least 0.5 % mass percent concentration dissolved. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes settling contaminants from a poly(dimethylsiloxane)/n-butane solution, wherein the poly(dimethylsiloxane) is added to up to 20 % mass percent concentration dissolved. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

purification

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises contacting a contaminated polymer solution with a solid medium at a temperature and pressure, wherein the polymer remains dissolved in a fluid solvent. The solid medium of the present invention is any solid material that removes at least some of the contaminants from a solution of the regenerated polymer dissolved in the fluid solvent of the present invention. While not wishing to be bound by any theory, applicants believe that solid media remove contaminants through a variety of mechanisms. Non-limiting examples of possible mechanisms include adsorption, absorption, size exclusion, ion exclusion, ion exchange, and other mechanisms that may be apparent to those of ordinary skill in the art. In addition, pigments and other contaminants commonly found in recycled polymers can be polar compounds and can preferentially interact with the solid medium, which can also be at least slightly polar. Polar-polar interactions are especially advantageous when using non-polar solvents such as alkanes as fluid solvents.

In one embodiment of the present invention, the solid medium is selected from inorganic substances, carbon-based substances, or mixtures thereof. Useful examples of inorganic substances include oxides of silicon, oxides of aluminum, oxides of iron, aluminum silicate, magnesium silicate, amorphous volcanic glass, silica, silica gel, diatomaceous earth, sand, quartz, recycled glass , alumina, perlite, fuller's earth, bentonite, and mixtures thereof. Useful examples of carbon-based materials include anthracite, carbon black, coke, activated carbon, cellulose, and mixtures thereof. In another embodiment of the present invention, the solid medium is recycled glass.

In one embodiment of the invention, the solid medium is contacted with the polymer in the vessel for a specified amount of time while the solid medium is agitated. In another embodiment, the solid medium is removed from the purer polymer solution via a solid-liquid separation step. Non-limiting examples of solid-liquid separation steps include filtration, decanting, centrifugation, and settling. In another embodiment of the present invention, the contaminated polymer solution is passed through a fixed bed of solid medium. In another embodiment of the present invention, the height or length of the fixed bed of solid medium is greater than 5 cm. In another embodiment of the present invention, the height or length of the fixed bed of solid medium is greater than 10 cm. In another embodiment of the present invention, the height or length of the fixed bed of solid medium is greater than 20 cm. In another embodiment of the present invention, the solid medium is replaced as needed to maintain the desired polymer purity. In another embodiment, the solid medium is regenerated and reused in the purification step. In another embodiment, the solid medium is regenerated by fluidizing the solid medium during the backflushing step.

In one embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/fluid solvent solution with a solid medium at a temperature and pressure, wherein the polyethylene remains dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/n-butane solution with a solid medium at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/n-butane solution with a solid medium at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/n-butane solution with a solid medium at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/n-butane solution with a solid medium at a pressure of from about 1,000 psig (6.89 MPa) to about 12,000 psig (82.74 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/n-butane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 10,000 psig (68.95 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/n-butane solution with a solid medium at a pressure of from about 4,000 psig (27.58 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting a polyethylene/n-butane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 1%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes contacting a polyethylene/n-butane solution with a solid medium, wherein the polyethylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 12%.

In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/propane solution with a solid medium at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/propane solution with a solid medium at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/propane solution with a solid medium at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/propane solution with a solid medium at a pressure of from about 3,000 psig (20.68 MPa) to about 20,000 psig (137.90 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/propane solution with a solid medium at a pressure of from about 5,000 psig (34.47 MPa) to about 15,000 psig (103.42 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polyethylene/propane solution with a solid medium at a pressure of from about 8,000 psig (55.16 MPa) to about 11,000 psig (75.84 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting a polyethylene/propane solution with a solid medium, wherein the polyethylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 1%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes contacting a polyethylene/propane solution with a solid medium, wherein the polyethylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polyethylene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/fluid solvent solution with a solid medium at a temperature and pressure, wherein the polypropylene remains dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/n-butane solution with a solid medium at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/n-butane solution with a solid medium at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/n-butane solution with a solid medium at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/n-butane solution with a solid medium at a pressure of from about 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/n-butane solution with a solid medium at a pressure of from about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/n-butane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting a polypropylene/n-butane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polypropylene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polypropylene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes contacting a polypropylene/n-butane solution with a solid medium, wherein the polypropylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 12%.

In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/propane solution with a solid medium at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/propane solution with a solid medium at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/propane solution with a solid medium at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/propane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/propane solution with a solid medium at a pressure of from about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polypropylene/propane solution with a solid medium at a pressure of from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting a polypropylene/propane solution with a solid medium, wherein the polypropylene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polypropylene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polypropylene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes contacting a polypropylene/propane solution with a solid medium, wherein the polypropylene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 16%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polypropylene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer includes contacting a polystyrene/fluid solvent solution with a solid medium at a temperature and pressure, wherein the polystyrene remains dissolved in the fluid solvent. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polystyrene/n-butane solution with a solid medium at a temperature of from about 90°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polystyrene/n-butane solution with a solid medium at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polystyrene/n-butane solution with a solid medium at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a polystyrene/n-butane solution with a solid medium at a pressure of from about 1,000 psig (6.89 MPa) to about 9,000 psig (62.05 MPa). In another embodiment, a method for purifying a regenerated polymer comprises contacting a polystyrene/n-butane solution with a solid medium at a pressure of from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting a polystyrene/n-butane solution with a solid medium at a pressure of from about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa). In another embodiment, a method for purifying a regenerated polymer includes contacting a polystyrene/n-butane solution with a solid medium, wherein the polystyrene is dissolved at a mass percent concentration of at least 0.5%. In another embodiment, the polystyrene is dissolved at a concentration of at least 1% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 2%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 3%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of at least 4%. In another embodiment, the polystyrene is dissolved at a concentration of at least 5% by mass. In another embodiment, a method for purifying a regenerated polymer includes contacting a polystyrene/n-butane solution with a solid medium, wherein the polystyrene is dissolved at a concentration of up to 20% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 18%. In another embodiment, the polystyrene is dissolved at a concentration of up to 16% by mass. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 14%. In another embodiment, the polystyrene is dissolved at a mass percent concentration of up to 12%.

In one embodiment, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane)/fluid solvent solution with a solid medium at a temperature and pressure, wherein the poly(dimethylsiloxane) Remain dissolved in fluid solvent. In another embodiment, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane)/n-butane solution with a solid medium at a temperature of from about 115°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane)/n-butane solution with a solid medium at a temperature of from about 120°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises contacting a poly(dimethylsiloxane)/n-butane solution with a solid medium at a temperature of from about 140°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises subjecting a poly(dimethylsiloxane)/n-butane solution to a pressure of about 500 psig (3.45 MPa) to about 2,100 psig (14.48 MPa) with solid medium contact. In another embodiment, a method for purifying a regenerated polymer comprises subjecting a poly(dimethylsiloxane)/n-butane solution to a pressure of about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa) with solid medium contact. In another embodiment, a method for purifying a regenerated polymer comprises subjecting a poly(dimethylsiloxane)/n-butane solution to a pressure of about 800 psig (5.52 MPa) to about 1,300 psig (8.96 MPa) with solid medium contact. In another embodiment, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane)/n-butane solution with a solid medium, wherein the poly(dimethylsiloxane) is treated at a concentration of at least 0.5 % mass percent concentration dissolved. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 1%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 2%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 3%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 4%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of at least 5%. In another embodiment, a method for purifying a regenerated polymer includes contacting a poly(dimethylsiloxane)/n-butane solution with a solid medium, wherein the poly(dimethylsiloxane) is added in a concentration of up to 20 % mass percent concentration dissolved. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 18%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 16%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 14%. In another embodiment, the poly(dimethylsiloxane) is dissolved at a mass percent concentration of up to 12%.

separate

In one embodiment of the present invention, a method for purifying a regenerated polymer comprises separating the purer polymer from a fluid solvent at a temperature and pressure, wherein the polymer precipitates out of solution and is no longer soluble in the fluid solvent middle. In another embodiment, the precipitation of a purer polymer from a fluid solvent is accomplished by reducing the pressure at a fixed temperature. In another embodiment, the precipitation of a purer polymer from a fluid solvent is accomplished by reducing the temperature at a fixed pressure. In another embodiment, the precipitation of the purer polymer from the fluid solvent is accomplished by increasing the temperature at a fixed pressure. In another embodiment, the precipitation of purer polymer from the fluid solvent is accomplished by reducing both temperature and pressure. By controlling temperature and pressure, the solvent can be partially or completely converted from liquid to gas phase. In another embodiment, the precipitated polymer is separated from the fluid solvent without complete conversion of the fluid solvent to a 100% gas phase by controlling the temperature and pressure of the solvent during the separation step. Isolation of the precipitated purer polymer is accomplished by any method of liquid-liquid or liquid-solid separation. Non-limiting examples of liquid-liquid or liquid-solid separations include filtration, decanting, centrifugation, and sedimentation.

In one embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/fluid solvent solution at a temperature and pressure, wherein the polyethylene is precipitated from the solution. In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/n-butane solution at a temperature of from about 0°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/n-butane solution at a temperature of from about 50°C to about 175°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/n-butane solution at a temperature of from about 100°C to about 160°C. In another embodiment, a method for purifying a regenerated polymer includes separating polyethylene from a polyethylene/n-butane solution at a pressure of from about 0 psig (0 MPa) to about 4,000 psig (27.58 MPa). In another embodiment, a method for purifying a regenerated polymer includes separating polyethylene from a polyethylene/n-butane solution at a pressure of from about 50 psig (0.34 MPa) to about 2,000 psig (13.79 MPa). In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/n-butane solution at a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/propane solution at a temperature of from about -42°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/propane solution at a temperature of from about 0°C to about 150°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/propane solution at a temperature of from about 50°C to about 130°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/propane solution at a pressure of from about 0 psig (0 MPa) to about 15,000 psig (103.42 MPa). In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/propane solution at a pressure of from about 50 psig (0.34 MPa) to about 5,000 psig (34.47 MPa). In another embodiment, a method for purifying a regenerated polymer comprises separating polyethylene from a polyethylene/propane solution at a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

In one embodiment, the method for purifying the regenerated polymer comprises separating polypropylene from the polypropylene/fluid solvent solution at a temperature and pressure, wherein the polypropylene is precipitated from the solution. In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/n-butane solution at a temperature of from about 0°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/n-butane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/n-butane solution at a temperature of about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/n-butane solution at a pressure of from about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In another embodiment, a method for purifying a regenerated polymer includes separating polypropylene from a polypropylene/n-butane solution at a pressure of from about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/n-butane solution at a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/propane solution at a temperature of from about -42°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes separating polypropylene from a polypropylene/propane solution at a temperature of from about 0°C to about 150°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/propane solution at a temperature of from about 50°C to about 130°C. In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/propane solution at a pressure of from about 0 psig (0 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, a method for purifying a regenerated polymer comprises separating polypropylene from a polypropylene/propane solution at a pressure of from about 50 psig (0.34 MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a method for purifying a regenerated polymer includes separating polypropylene from a polypropylene/propane solution at a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

In one embodiment, a method for purifying a regenerated polymer includes separating polystyrene from a polystyrene/fluid solvent solution at a temperature and pressure, wherein the polystyrene is precipitated from the solution. In another embodiment, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene/n-butane solution at a temperature of from about 0°C to about 220°C. In another embodiment, a method for purifying a regenerated polymer includes separating polystyrene from a polystyrene/n-butane solution at a temperature of from about 100°C to about 200°C. In another embodiment, a method for purifying a regenerated polymer includes separating polystyrene from a polystyrene/n-butane solution at a temperature of from about 130°C to about 180°C. In another embodiment, a method for purifying a regenerated polymer includes separating polystyrene from a polystyrene/n-butane solution at a pressure of from about 0 psig (0 MPa) to about 2,000 psig (13.79 MPa). In another embodiment, a method for purifying a regenerated polymer includes separating polystyrene from a polystyrene/n-butane solution at a pressure of from about 50 psig (0.34 MPa) to about 1,500 psig (10.34 MPa). In another embodiment, a method for purifying a regenerated polymer comprises separating polystyrene from a polystyrene/n-butane solution at a pressure of from about 75 psig (0.52 MPa) to about 1,000 psig (6.89 MPa).

In one embodiment, a method for purifying a regenerated polymer includes isolating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/fluid solvent solution at a temperature and pressure, wherein the Poly(dimethylsiloxane) precipitated out. In another embodiment, a method for purifying a regenerated polymer comprises isolating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butane solution at a temperature of from about 0°C to about 220°C oxane). In another embodiment, a method for purifying a regenerated polymer comprises isolating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butane solution at a temperature of from about 115°C to about 200°C oxane). In another embodiment, a method for purifying a regenerated polymer comprises isolating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butane solution at a temperature of from about 120°C to about 180°C oxane). In another embodiment, a method for purifying a regenerated polymer comprises separating from a poly(dimethylsiloxane)/n-butane solution at a pressure of from about 0 psig (0 MPa) to about 1,500 psig (10.34 MPa) Polydimethylsiloxane). In another embodiment, a method for purifying a regenerated polymer comprises removing a poly(dimethylsiloxane)/n-butane solution from a poly(dimethylsiloxane)/n-butane solution at a pressure of from about 50 psig (0.34 MPa) to about 1,000 psig (6.89 MPa). The poly(dimethylsiloxane) was isolated. In another embodiment, a method for purifying a regenerated polymer comprises separating from a poly(dimethylsiloxane)/n-butane solution at a pressure of from about 75 psig (0.52 MPa) to about 500 psig (3.45 MPa) Polydimethylsiloxane).

III test method

The test methods described herein are used to measure the effectiveness of various methods of purifying polymers. Specifically, the method demonstrates the effectiveness of a given purification method in improving color and translucency/transparency (i.e., bringing the color and opacity of the regenerated polymer closer to the color and opacity of the unpigmented virgin polymer transparency), reduction or elimination of elemental contamination (i.e. removal of heavy metals), reduction or elimination of non-combustible pollutants (i.e. inorganic fillers), reduction or elimination of volatile compounds (especially those that contribute to malodorous odors in regenerated polymers) , and reducing or eliminating polymer contamination (ie, polyethylene contamination in polypropylene).

Color and Opacity Measurements :

The color and opacity/translucency of the polymer are important parameters in determining whether the polymer can achieve the desired visual aesthetics of articles made from the polymer. Recycled polymers, especially those derived from post-consumer products, are often dark and opaque due to residual pigments, fillers and other contaminants. Therefore, color and opacity measurements are important parameters for determining the effectiveness of methods used to purify polymers.

Prior to color measurement, samples of polymer powder or pellets were compression molded into 30 mm wide x 30 mm long x 1 mm thick square coupons (with rounded corners). Powder samples were first densified at room temperature (approximately 20°C to 23°C) by cold pressing the powder into sheets, using clean unused aluminum foil as the contact barrier between the stainless steel press plates. About 0.85 g of the cold-pressed powder or pellets were then placed in a Type C Carver Press (Carver, Inc., Wabash, IN 46992-0554 USA) preheated to 200°C using an aluminum platen, an unused aluminum foil separator, and with The specimens were pressed onto stainless steel gaskets of the cavity corresponding to the aforementioned dimensions of the square specimen. The samples were heated for 5 minutes before applying pressure. After 5 minutes, the compact is then compressed with a hydraulic pressure of at least 2 tons (1.81 metric tons) for at least 5 seconds and then released. The mold stack is then removed and placed between two thick flat metal heat sinks for cooling. The foil contact barrier was then peeled from the sample and discarded. The burrs around the sample on at least one side are stripped to the edge of the mold, and the sample is then pushed through the form. Each sample was visually evaluated for void/bubble defects, and color measurements were made using only samples with no defects in the color measurement area (0.7" (17.78 mm) minimum diameter).

The color of each sample was characterized using the International Commission on Illumination (CIE) L*, a*, b* three-dimensional color space. The dimension L* is a measure of sample brightness, where L*=0 corresponds to the darkest black sample and L*=100 corresponds to the brightest white sample. The dimension a* is a measure of the red or green color of the sample, where positive values of a* correspond to red and negative values of a* correspond to green. The dimension b* is a measure of the blueness or yellowness of the sample, where positive values of b* correspond to yellow and negative values of b* correspond to blue. The L*a*b* value of each 30 mm wide x 30 mm long x 1 mm thick square specimen sample was measured on a HunterLab model LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-5280, USA). The spectrophotometer was constructed with a D65 as the standard illuminator, a viewing angle of 10°, an area diameter viewing angle of 1.75" (44.45mm), and a port diameter of 0.7" (17.78mm).

The opacity of each sample was determined using the aforementioned HunterLab spectrophotometer using the Contrast Ratio Opacity Mode, which is a measure of how much light is transmitted through the sample (ie, a measure of the translucency of the sample). Two measurements were taken to determine the opacity of each sample. The luminance value of the sample Y _{white backing} was measured once with a white backing as the background, and the luminance value Y _{black backing} of the sample was measured once with a black backing as the background. The opacity is then calculated from the luminance value using the following Equation 3:

Formula 3

Elemental Analysis :

Many recycled polymers have unacceptably high concentrations of heavy metal contamination. The presence of heavy metals such as lead, mercury, cadmium and chromium may prevent the use of recycled polymers in certain applications such as food or drug contact applications or medical device applications. Therefore, measuring the concentration of heavy metals is important in determining the effectiveness of a method for purifying polymers.

Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Prepare test solutions: Based on sample availability, n=2 to n=6, combine approximately 0.25 g of sample with 4 mL of concentrated nitric acid and 1 mL of concentrated hydrofluoric acid (HF). Samples were digested using an Ultrawave microwave digestion protocol consisting of a 20 min ramp to 125°C, a 10 min ramp to 250°C, and a 20 min hold at 250°C. Cool the digested samples to room temperature. After adding 0.25 mL of 100 ppm Ge and Rh as internal standards, the digested samples were diluted to 50 mL. To evaluate the accuracy of the measurements, predigestion spikes were prepared by doping the native polymer. Samples doped with native polymer were weighed using the same procedure described above, and doped with appropriate amounts of each element of interest standard including the following: Na, Al, Ca, Ti, Cr, Fe, Ni, Cu , Zn, Cd and Pb. The spikes were prepared at two different levels: "low level spike" and "high level spike". Each spike was prepared in triplicate. In addition to virgin polymer incorporation, billets were incorporated to confirm that no errors occurred during pipetting and to track recovery throughout the process. The doped blank samples were also prepared in triplicate at two different levels and processed in the same manner as the doped virgin polymer and test samples. 9 was prepared by preparing 0.05ppb, 0.1ppb, 0.5ppb, 1ppb, 5ppb, 10ppb, 50ppb, 100ppb and 500ppb solutions containing Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd and Pb point calibration curve. All calibration standards were prepared by diluting a pure standard reference solution with 4 mL of concentrated nitric acid and 1 mL of concentrated HF and 0.25 mL of 100 ppm Ge and Rh as internal standards. Prepared standards, test samples, and doped test samples were analyzed using Agilent's 8800 ICP-QQQMS, optimized according to the manufacturer's recommendations. The m/z of each analyte monitored and the collision cell gas used for the analysis are as follows: Na, 23m/z, _H2 ; Al, 27m/z, _H2 ; Ca, 40m/z, _H2 ; Ti, 48m/z, _H2 ; Cr, 52m/z, He; Fe, 56m/z, _H2 ; Ni, 60m/z; no gas; Cu, 65m/z, no gas; Zn, 64m/z , He; Cd, 112m/z; _H2 ; Ge was used as the internal standard <103m/z for all elements, and Rh was used for all elements >103m/z.

Residual Ash Content :

Many recycled polymers contain various fillers such as calcium carbonate, talc, and glass fibers. Although useful in the original application of the recycled polymer, these fillers alter the physical properties of the polymer in ways that may not be desirable for the next application of the recycled polymer. Therefore, measuring the amount of filler is important in determining the effectiveness of a method for purifying polymers.

Thermogravimetric analysis (TGA) is performed to quantify the amount of non-combustible material (sometimes also referred to as ash content) in the sample. About 5 mg to 15 mg of sample was loaded onto a platinum sample pan and heated to 700°C in an air atmosphere at a rate of 20°C/min in a TA Instruments Model Q500 TGA instrument. The samples were kept isothermal at 700°C for 10 min. After the isothermal hold, the residual mass percent was measured at 700°C.

Odor Analysis :

Odor sensory analysis was performed by placing approximately 3 g of each sample in a 20 mL glass bottle and equilibrating the samples for at least 30 min at room temperature. After equilibration, each vial was opened and the headspace was sniffed (rabbit sniffed) by a trained grader to determine odor intensity and descriptor characteristics. Odour intensity is graded according to the following scales:

5 = very strong

4 = strong

3 = Moderate

2 = weak to moderate

1 = weak

0 = no smell

Polymer Contamination Analysis :

Many regenerated polymers, especially those derived from mixed streams, may contain undesirable polymer contaminants. Without wishing to be bound by any theory, polymer contamination (eg polyethylene in polypropylene) may affect the physical properties of the polymer due to the presence of heterogeneous phases and the resulting weak interfaces. In addition, polymer contamination may also increase the opacity of the polymer and have an effect on color. Therefore, measuring the amount of polymer contamination is important in determining the effectiveness of a method for purifying polymers.

Differential scanning calorimetry (DSC) was used to evaluate semi-crystalline polymer contamination. For example, to measure the amount of polyethylene contamination in polypropylene, 2 wt %, 4 wt %, 6 wt %, 8 wt % and 10 wt % HB5502F HDPE (Formosa Plastics Corporation, USA) prepared a set of five polypropylene/polyethylene blends in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, BV). Approximately 5 mg to 15 mg of each sample was sealed in an aluminum DSC pan and analyzed on a TA Instruments Model Q2000 DSC using the following method:

1. Equilibrate at 30.00°C

2. Ramp up to 200.00°C at 20.00°C/min

3. Mark the end of cycle 0

4. Ramp down to 30.00°C at 20.00°C/min

5. Mark the end of cycle 1

6. Ramp up to 200.00°C at 20.00°C/min

7. Mark the end of cycle 2

8. Ramp down to 30.00°C at 20.00°C/min

9. Mark the end of cycle 3

10. Ramp up to 200.00°C at 5.00°C/min

11. Mark the end of cycle 4

The 5.00°C/min DSC thermogram was used to calculate the melting enthalpy of the HDPE peak at about 128°C for each sample of known HDPE content. The linear calibration curve shown in Figure 2 was established via a plot of melting enthalpy versus known HDPE concentration (wt %).

Samples with unknown PE content were analyzed using the same DSC equipment and method described above. The PE content was calculated using the above calibration curve. The specific HDPE used to generate the calibration curve will be more likely to have a different degree of crystallinity than the polyethylene (or polyethylene blend) contamination that may be present in the regenerated polymer sample. Crystallinity can independently affect the measured melting enthalpy of polyethylene, and thus the resulting calculation of polyethylene content. However, the DSC test methods described herein are intended as a relative measure to compare the effectiveness of different methods for purifying polymers and are not meant to be a rigorous quantification of polyethylene content in polymer blends. Although the above method describes the measurement of polyethylene contamination in polypropylene, the method can be applied to other semi-crystalline polymers using different temperature ranges and the measurement of peaks in DSC thermograms. In addition, alternative methods such as nuclear magnetic resonance (NMR) spectroscopy can also be used to measure the amount of both semi-crystalline and amorphous polymer contamination in a sample.

Example

The following examples further describe and demonstrate embodiments within the scope of the present invention. These examples are given for illustrative purposes only and should not be construed as limiting the invention, as many modifications may be made without departing from the spirit and scope of the invention.

Example 1

Samples from post-consumer recycled polypropylene mixed color flakes were sourced from recycled resin suppliers. Post-consumer recycled polypropylene originates from the United States and Canada. The ready-to-use color mixing flakes were homogenized via mixing on a Century/W&P ZSK30 twin screw extruder equipped with two 30 mm general purpose screws, each with standard mixing and conveying elements. The screw speed was about 50 rpm, the feeder throughput was about 20 lb/hr (9.07 kg/hr), and the barrel temperature ranged from about 210°C at the die to about 150°C at the feed throat. The grey strands exiting the extruder were cooled in a room temperature water bath, air dried, and chopped into pellets.

The samples were characterized using the test methods disclosed herein, and the data obtained are summarized in Table 1. The purpose of this example is to show the properties of a representative resin from post-consumer recycling prior to purification.

The pellets and corresponding square specimens are dark grey as indicated by the L*a*b* values for the square specimens. The opacity of the samples averaged about 100% opaque (ie, not translucent). A photograph of the square specimen is shown in Figure 4 as Example 1. As shown in Figure 4, the sample is dark in color and lacks translucency.

This example serves as a representative baseline for heavy metal contamination found in polypropylene from post-consumer recycling. When compared to the other examples, heavy metal contamination was found to be much greater in the ready-to-use polypropylene from post-consumer recycling.

The samples of Example 1 had an ash content value of about 1.2117 wt% on average, which also served as a baseline for the amount of non-combustible materials typically present in polypropylene from post-consumer recycling.

This example also serves as a representative baseline for contamination by odorous compounds found in post-consumer recycled polypropylene. The sample of Example 1 was found to have an odor intensity of 3.75 on a 5-point scale (5 strongest) and was described as having a "garbage", "dusty" or "sour" odor.

This example also serves as a representative baseline for polyethylene contamination found in polypropylene from post-consumer recycled polypropylene. The samples of Example 1 had an average polyethylene content of about 5.5% by weight.

Example 2

The samples of post-consumer recycled polypropylene color mixing flakes described in Example 1 were processed using the experimental equipment shown in Figures 3A and 3B and the following procedure:

1. Load 286 g of color mixing flakes into a Parr Instrument Company model 4552M 7.57 liter autoclave equipped with an overhead mechanical stirrer.

2. The autoclave was then completely filled with n-butane and equilibrated to an internal fluid temperature of 140°C and a fluid pressure of 900 psig (6.21 MPa).

3. The material in the autoclave was then extracted using the experimental configuration shown in Figure 3A and the following procedure:

a. The system was stirred at 140° C. and 900 psig (6.21 MPa) for 10 min.

b. After stirring, let the system stand at 140°C and 900 psig (6.21 MPa) for 10 min.

c. At 140°C and 900 psig (6.21 MPa), inject one vessel volume of n-butane into the sample collection flask through the autoclave.

d. Repeat the above extraction procedure more than four times.

e. Material collected for all extraction cycles is marked as "Fraction 1".

4. The material remaining in the autoclave after extraction was then dissolved in n-butane using the experimental configuration shown in Figure 3B and the following procedure:

a. Equilibrate the system pressure to 1800 psig (12.41 MPa).

b. The system was stirred at 140°C and 1800 psig (12.41 MPa) for 10 min.

c. The stirring was then stopped and the solution was allowed to settle for 30 min at 140°C and 1800 psig (6.21 MPa).

d. After settling, the solution of the autoclave was removed by displacement with pressurized nitrogen (pre-equilibrated to 140°C and 1800 psig). The solution exiting the autoclave through the dip tube was then passed through two columns of thermally tracked solid media. Each column has an ID of 0.68" (1.73 cm) and a length of approximately 9.5" (24.13 cm). The first column contained about 21 g of 8- to 16-mesh bleaching earth (Jaxon Filtration, JF 752-8/16, USA) mixed in a beaker with about 21 g of 30- to 60-mesh bleaching earth (Jaxon Filtration, JF). 752-3060, USA) for premixing. The second column contained about 21 g of silica gel (Silicycle ultrapure silica gel, SiliaFlash GE60, Parc-Technologies, USA) which was run in a beaker with about 21 g of alumina (activated alumina, Selexsorb CDX, 7×14, BASF, USA) premix. The fluid stream exiting the bottom of the second pressure vessel is depressurized through an expansion valve into a sidearmed Erlenmeyer flask. After depressurizing the fluid stream into the Erlenmeyer flask, the solvent vapor was vented through the side arm port and any liquid/solid collected as a fraction in the flask. Each fraction contained approximately 30 g of material and was labeled sequentially starting with "FRACTION 2". Fractions were collected until no more material could be observed to elute into the flask.

5. After all samples have been collected, allow the autoclave to equilibrate to atmospheric pressure and room temperature. All residual material in the autoclave was then collected as a residual sample.

Data for Fraction 3 samples collected according to the procedures disclosed herein are summarized in Table 1 .

The solid isolated in fraction 3 in this example was white. When the white solid from Fraction 3 was compression molded into square specimens, the specimens were colorless and transparent and similar in appearance to virgin polypropylene. A photograph of the square sample made from Fraction 3 is shown in Figure 4 as Example 2. For reference, virgin polypropylene is shown in Figure 4 as Example 4. As shown in Figure 4, the sample was transparent and comparable in color and translucency to virgin polypropylene. The L*a*b* values show that the square sample is substantially colorless and exhibits significant color relative to the square sample of Example 1 (ie, ready-to-use polypropylene derived from post-consumer). improve. The L* value of the square samples of Fraction 3 from Example 2 averaged 80.44, which was greatly improved when compared to the L* value of the square samples of Example 1, which averaged 39.76. The opacity of the square samples of Fraction 3 from Example 2 averaged 10.30% opaque (ie, about 90% translucent) when compared to the opacity values of the square samples of Example 1, which averaged about 100% opaque The opacity is also greatly improved in comparison.

The concentration of heavy metal contamination of the sample from Fraction 3 of Example 2 was also greatly improved when compared to the sample of Example 1 . For example, the sodium concentration in the samples from Fraction 3 of Example 2 averaged only 4,100 ppb, while the sodium concentration in the samples from Example 1 averaged 136,000 ppb (a reduction of about 97%). Relative to the sample of Example 1, the measured concentration of all other elements was reduced by 77% to 100% for the sample from Fraction 3 of Example 2.

The samples from Fraction 3 of Example 2 had an ash content value of about 0.3874 wt% on average, which was significantly lower than the ash content value of the samples of Example 1, which averaged about 1.2117 wt%.

The sample from Fraction 3 of Example 2 was found to have an odor intensity of 0.5 on a 5-point scale (5 strongest) when compared to the odor intensity of the sample of Example 1 (which had an odor intensity of 3.75) , the odor intensity was greatly improved. Despite the low odor intensity, the sample from Fraction 2 of Example 2 was described as having a "plastic" odor similar to virgin polypropylene.

The samples of Fraction 3 from Example 2 had an average polyethylene content value of about 1.1 wt % when compared to the polyethylene content of the samples of Example 1 which averaged about 5.5 wt %. was greatly improved.

Example 3

The samples of post-consumer recycled polypropylene color mixing flakes described in Example 1 were processed using the experimental equipment shown in Figures 3A and 3B and the following procedure:

6. Load 173 g of color mixing flakes into a Parr Instrument Company model 4552M 7.57 liter autoclave equipped with an overhead mechanical stirrer.

7. The autoclave was then completely filled with n-butane and equilibrated to an internal fluid temperature of 140°C and a fluid pressure of 900 psig (6.21 MPa).

8. Then, extract the material in the autoclave using the experimental configuration shown in Figure 3A and the following procedure:

f. The system was stirred at 140°C and 900 psig (6.21 MPa) for 10 min.

g. After stirring, the system was allowed to stand at 140°C and 900 psig (6.21 MPa) for 10 min.

h. Inject one vessel volume of n-butane into the sample collection flask through the autoclave at 140°C and 900 psig (6.21 MPa).

i. Repeat the above extraction procedure more than four times.

j. The samples collected for each extraction cycle are sequentially labeled as "FRACTION 1" to "FRACTION 5".

9. The material remaining in the autoclave after extraction was then dissolved in n-butane using the experimental configuration shown in Figure 3B and the following procedure:

e. Equilibrate the system pressure to 1800 psig (12.41 MPa).

f. The system was stirred at 140°C and 1800 psig (12.41 MPa) for 10 min.

g. The stirring was then stopped and the solution was allowed to settle for 60 min at 140°C and 1800 psig (6.21 MPa).

h. After settling, the autoclave solution was removed by displacement with pressurized n-butane (pre-equilibrated to 140°C and 1800 psig). The solution exiting the autoclave through the dip tube was then passed through two columns of thermally tracked solid media. Each column has an ID of 0.68" (1.73 cm) and a length of approximately 9.5" (24.13 cm). In this example, both columns are empty and do not contain any solid medium. The fluid stream exiting the bottom of the second pressure vessel is depressurized through an expansion valve into a sidearmed Erlenmeyer flask. After depressurizing the fluid stream into the Erlenmeyer flask, the solvent vapor was vented through the side arm port and any liquid/solid collected as a fraction in the flask. Each fraction contained approximately 30 g of material and was labeled sequentially starting with "FRACTION 6". Fractions were collected until no more material could be observed to elute into the flask.

10. After collecting all samples, equilibrate the autoclave to atmospheric pressure and room temperature. All residual material in the autoclave was then collected as a residual sample.

Data for Fraction 6 samples collected according to the procedures disclosed herein are summarized in Table 1 .

The solid isolated in fraction 6 in this example was off-white to yellow. When the off-white to yellow solid from Fraction 6 was compression molded into square coupons, the samples had a yellow appearance. Photographs of square specimens are shown in Figure 4 as Example 3. As shown in Figure 4, the color and translucency of the sample of Example 3 were improved relative to the sample of Example 1, but not comparable to virgin polypropylene (shown in Figure 4 as Example 4). Even without the solid medium contacting step, the L*a*b* values show that the square sample of Fraction 6 from Example 3 is relative to the sample of Example 1 (ie, the ready-to-use, consumer-derived post polypropylene) was improved in color. The L* value of the square samples from Fraction 6 of Example 3 averaged 72.41, which was improved when compared to the L* value of the square samples of Example 1, which averaged 39.76. The opacity of Fraction 6 square samples from Example 3 averaged 35.25% opaque, which was also reduced when compared to the opacity values of Example 1 square samples, which averaged about 100% opaque. improve.

The concentration of heavy metal contamination of the sample from Fraction 6 of Example 3 was also improved when compared to the sample of Example 1 . For example, the sodium concentration in the samples from Fraction 6 of Example 3 averaged only 16,400 ppb, while the sodium concentration in the samples from Example 1 averaged 136,000 ppb (a reduction of about 88%). All other element concentrations measured for samples from Fraction 6 of Example 3 were reduced by 82% to 100% relative to the samples of Example 1 .

The samples from Fraction 6 of Example 3 had an ash content value of about 0.2292 wt% on average, which was significantly lower than the ash content value of the samples of Example 1, which averaged about 1.2117 wt%.

The sample from Fraction 6 of Example 3 was found to have an odor intensity of 0.5 on a 5-point scale (5 out of 5 strongest) when compared to the odor intensity of the sample of Example 1, which had an odor intensity of 3.75 , the odor intensity was greatly improved. Despite the low odor intensity, the sample from Fraction 6 of Example 3 was described as having a "plastic" odor similar to virgin polypropylene.

The samples of Fraction 6 from Example 3 had an average polyethylene content value of about 1.0 wt % when compared to the polyethylene content of the samples of Example 1 which averaged about 5.5 wt %. was greatly improved.

Example 4 - Virgin Polypropylene Comparative Sample

Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, B.V.) was used for all "virgin PP" comparison samples. Pellets of virgin PP were processed into square coupons according to the methods described herein. The average L*a*b* values of samples made from raw PP were 85.13±0.18, -0.71±0.01 and 2.27±0.02, respectively. The square samples had an average opacity of 7.56% ± 0.21% opacity. This example serves as a comparison of the amount of heavy metal contamination found in a representative sample of virgin polypropylene. The samples of virgin polypropylene had an ash content value of about 0.3031 wt% on average. Pellets of virgin PP had an odor intensity of 0.5 on a 5-point scale (5 strongest) and had an odor described as "plastic". Polyethylene was not detected in samples of virgin propylene.

Table 1: Color, Contamination and Odor Removal for Examples 1 to 4

Unless expressly excluded or otherwise limited, each document cited herein, including any cross-reference or related patents or patent applications, is hereby incorporated by reference in its entirety.

The citation of any document is not intended to be prior art to any invention disclosed or claimed herein, either alone or in any combination with any other reference or references, or to teach, teach, suggest or disclose the endorsement of any such invention. Furthermore, to the extent that any meaning or definition of a term in this application conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this application shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications as fall within the scope of this invention.

Claims (15)

1. A method for purifying a regenerated polymer, the method comprising: a. obtaining the recycled polymer, wherein the recycled polymer is selected from the group consisting of post-consumer polymers, post-industrial polymers, and combinations thereof; b. contacting the regenerated polymer with a first fluid solvent having a normal boiling point less than about 70°C at a temperature of about 80°C to about 220°C and a pressure of about 150 psig (1.03 MPa) to about 15,000 psig (103.42 MPa) , to produce an extracted regenerated polymer; c. Dissolving the extracted regenerated polymer in a solvent selected from the first fluid solvent, the two-fluid solvents, and mixtures thereof, to produce a first solution comprising the polymer and suspended contaminants; d. Settling the first solution comprising the polymer and suspended contaminants at a temperature of about 90°C to about 220°C and a pressure of about 350 psig (2.41 MPa) to about 20,000 psig (137.90 MPa) to produce a polymer comprising and a second solution of remaining contaminants; e. Purify the second solution by contacting the second solution with a solid medium at a temperature of about 90°C to about 220°C and a pressure of about 350 psig (2.41 MPa) to about 20,000 psig (137.90 MPa) to yield a third solution comprising a purer polymer; and f. separating the purer polymer from the third solution; wherein the second fluid solvent has the same chemical composition as the first fluid solvent or a different chemical composition. 2. The method of claim 1, wherein the purer solution is separated from the third solution at a temperature of about 0°C to about 220°C and a pressure of about 0 psig (0 MPa) to 2,000 psig (13.79 MPa). of polymers. 3. The method of claim 1, wherein the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 0.5%. 4. The method of claim 1, wherein the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 2%. 5. The method of claim 1, wherein the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of at least 5%. 6. The method of claim 1, wherein the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of up to 20% by mass. 7. The method of claim 1, wherein the regenerated polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of up to 12%. 8. The method of claim 1, wherein the recycled polymer is a polymer derived from post-consumer recycling. 9. The method of claim 1, wherein the recycled polymer is polystyrene. 10. The method of claim 1, wherein the recycled polymer is poly(dimethylsiloxane). 11. The method of claim 1, wherein the recycled polymer is a polypropylene homopolymer or is a primary polypropylene copolymer. 12. The method of claim 1, wherein the polymer is a polyethylene homopolymer or a primary polyethylene copolymer. 13. The method of claim 1, wherein the fluid solvent has a normal boiling point of less than about 0°C and greater than about -45°C and a normalized enthalpy change of vaporization of less than about +25 kJ/mol. 14. The method of claim 1, wherein the fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof. 15. The method of claim 14, wherein the aliphatic hydrocarbon is selected from the group consisting of _C1 - _C6 aliphatic hydrocarbons and mixtures thereof.