CN110072927B

CN110072927B - Process for purifying reclaimed polymers

Info

Publication number: CN110072927B
Application number: CN201780076813.0A
Authority: CN
Inventors: 约翰·蒙克里夫·莱曼; 迪米特里斯·伊奥安尼斯·科利亚斯; 汉斯·肖内曼; 卡拉·威廉姆斯
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2016-12-20
Filing date: 2017-12-13
Publication date: 2021-12-21
Anticipated expiration: 2037-12-13
Also published as: CN110072927A; JP2020513458A; CA3045910A1; RU2719851C1; WO2018118579A1; CA3045910C; MX2019007400A; BR112019012860A2; BR112019012860B1; JP6877547B2

Abstract

The present invention provides a process for purifying reclaimed polymers. The method comprises obtaining a reclaimed polymer; contacting the reclaimed polymer with a first fluid solvent to produce an extracted reclaimed polymer; the extracted reclaimed polymer is then dissolved in a solvent to produce a first solution comprising the polymer and suspended contaminants. The first solution is allowed to settle to produce a second solution comprising the polymer and the 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. Finally, a purer polymer is isolated from the third solution.

Description

Process for purifying reclaimed polymers

Technical Field

The present invention generally relates to a process for purifying contaminated polymers by using a pressurized solvent and a solid medium. More particularly, the present invention relates to a process for purifying recycled polymers such as post-consumer and post-industrial recycled plastics to produce colorless or transparent odorless virgin polymers. The process is particularly useful for the purification of polyolefins such as polyethylene and polypropylene.

Background

Polymers, especially synthetic plastics, are ubiquitous in everyday life due to their relatively low production costs and a well-balanced balance of material properties. Synthetic plastics are widely used in various applications such as packaging, automotive parts, medical devices and consumer products. To meet the high demands of these applications, billions of pounds of synthetic plastics are produced worldwide each year. The vast majority of synthetic plastics are made ofScarce fossil resources such as oil and gas production. Furthermore, the production of CO from synthetic plastics made from fossil resources₂As a by-product.

The widespread use of synthetic plastics has resulted in millions of tons of plastic waste being generated each year. While most plastic waste is landfilled via municipal solid waste programs, most plastic waste is found in the environment as a mess, which is unsightly and can be harmful to the ecosystem. Plastic waste is often flushed into the river system and eventually out of the sea.

Recycling of plastics has become a solution to alleviate the problems associated with the widespread use of plastics. Recycling and reusing plastics transfers waste from waste landfills and reduces the need for virgin plastics made from fossil resources, thereby reducing greenhouse gas emissions. In developed areas, such as the united states and the european union, plastic recycling is increasing due to increased awareness of 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). In MRF, the 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 (LDPE), poly (vinyl chloride) (PVC), Polystyrene (PS), Polycarbonate (PC) and Polyamide (PA). The single or mixed streams can then be further classified, washed and reprocessed into pellets suitable for reuse in plastic processing (e.g., blow molding and injection molding).

Although recycled plastics are classified as predominantly homogeneous and washed with aqueous and/or caustic solutions, the final reprocessed pellets typically remain highly contaminated with unwanted waste impurities such as spoiled food residues and residual flavor components. In addition, recycled plastic pellets other than those from recycled beverage containers are dark colored due to the mixture of dyes and pigments typically used to color plastic articles. While there are some applications that are not sensitive to color and contamination (e.g., black plastic coating containers and hidden automotive parts), most require colorless pellets. The need for high quality "virgin" recycled resins is particularly important for food and drug contact applications such as food packaging. In addition to being contaminated 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) contaminants in recycled PP and PP contaminants in recycled Polyethylene (PE).

Mechanical recycling, also known as secondary recycling, is a process by which recycled plastic waste is converted into a reusable form for subsequent manufacturing. A more detailed review of mechanical Recycling and other plastic recovery methods is described in S.M.Al-Salem, P.Lettieri, J.Baeyens, "Recycling and recovery routes of Plastic Solid Waste (PSW): A review", cost Management, Volume 29, Issue 10, October 2009, Pages 2625-. Although advances in mechanical recycling technology have improved the quality of recycled polymers to some extent, there are fundamental limitations to mechanical purification methods, such as physical entrapment of pigments within the polymer matrix. Thus, even with the improvement of mechanical recycling technology, the dark color and high levels of chemical contamination in currently available recycled plastic waste prevents the widespread use of recycled resins by the plastic industry.

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

For example, U.S. patent 7,935,736 describes a process 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 the polyester from the solvent using a precipitant.

In another example, U.S. patent 6,555,588 describes a process for producing polypropylene blends from plastic mixtures containing other polymers. The' 588 patent describes extracting contaminants from the polymer at a temperature below the dissolution temperature of the polymer in a selected solvent, such as hexane, for a specified residence time period. The' 588 patent also describes increasing the temperature of the solvent (or second solvent) prior to filtration to dissolve the polymer. The' 588 patent also describes the use of shear or flow to precipitate polypropylene from solution. The polypropylene blend described in the' 588 patent contains up to 5.6 wt% polyethylene contaminants.

In another example, european patent application 849,312 (german to english) describes a process for obtaining purified polyolefin from polyolefin-containing plastic mixtures or polyolefin-containing waste. The' 312 patent application describes the extraction of a polyolefin blend or waste with the hydrocarbon fraction of gasoline or diesel fuel having a boiling point above 90 ℃ at a temperature between 90 ℃ and the boiling point of the hydrocarbon solvent. The' 312 patent application also describes contacting the hot polyolefin solution with bleaching clay and/or activated carbon to remove extraneous components from the solution. The' 312 patent also describes cooling the solution to a temperature below 70 ℃ to crystallize the polyolefin, and then removing the adhering solvent by heating the polyolefin above the melting point of the polyolefin, or evaporating the adhering solvent in a vacuum or passing a gas stream through the polyolefin for precipitation, and/or extracting the solvent with an alcohol or ketone having a boiling point below the melting point of the polyolefin.

In another example, U.S. patent 5,198,471 describes a method for separating polymers from a physically mixed solid mixture (e.g., waste plastic) containing multiple polymers at a first lower temperature using a solvent to form a first single phase solution and a residual solid component. The' 471 patent also describes heating the solvent to a higher temperature to dissolve additional polymer that is not soluble at the first, lower temperature. The' 471 patent describes filtration of undissolved components.

In another example, U.S. patent 5,233,021 describes a method of extracting pure polymer components from a multi-component structure (e.g., waste carpeting) by dissolving each component in a supercritical fluid at an appropriate temperature and pressure and then varying the temperature and/or pressure to extract the specific components sequentially. However, similar to the '471 patent, the' 021 patent only describes filtration of the precipitated component.

In another example, U.S. patent 5,739,270 describes a method and apparatus for continuously separating a polymer component of a plastic from contaminants and other components of the plastic using a co-solvent and a working fluid. The co-solvent at least partially dissolves the polymer, and the second fluid (i.e., in a liquid, critical, or supercritical state) dissolves the components from the polymer and precipitates some of the dissolved polymer from the co-solvent. The' 270 patent also describes the step of filtering the thermoplastic co-solvent (with or without the working fluid) to remove particulate contaminants, such as glass particles.

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

Thus, there remains a need for an improved solvent-based process 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 unit operations, produces a polymer without causing significant cross-contamination of the polymer, produces a substantially colorless polymer, and produces a substantially odorless polymer.

Disclosure of Invention

A process for purifying reclaimed polymers is provided. The method comprises the following steps:

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

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

c. dissolving the extracted reclaimed polymer in a solvent selected from the group consisting of a first fluid solvent, a second fluid solvent, and mixtures thereof at a temperature of from about 90 ℃ to about 220 ℃ and a pressure of from about 350psig (2.41MPa) to about 20,000psig (137.90MPa) to produce a first solution comprising the polymer and suspended contaminants;

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

e. purifying the second solution by contacting the second solution with a solid medium at a temperature of about 90 ℃ to about 220 ℃ and a pressure of about 350psig (2.41MPa) to about 20,000psig (137.90MPa) to produce a third solution comprising a purer polymer; and

f. separating the purer polymer from the third solution.

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

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

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

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

In one embodiment, the reclaimed polymer is a polymer derived from post-consumer recycle. In another embodiment, the reclaimed polymer is polystyrene. In another embodiment, the polymer is poly (dimethylsiloxane). In another embodiment, the reclaimed polymer is a polypropylene homopolymer or is a primary polypropylene copolymer. In another embodiment, the reclaimed polymer is a polyethylene homopolymer or is a major polyethylene copolymer. In another embodiment, the fluid solvent has a normal boiling point of less than about 0 ℃ and greater than about-45 ℃ and a normal enthalpy 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 C₁-C₆Aliphatic hydrocarbons and mixtures thereof. In another embodiment, the aliphatic hydrocarbons and mixtures thereof consist essentially of C₄Aliphatic hydrocarbons.

In another embodiment, the fluid solvent consists essentially of C₄Liquefied 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 purifying steps is from about 110 ℃ to about 170 ℃.

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

In one embodiment, the solid medium is selected from the group consisting of inorganic substances, carbon-based substances, and mixtures thereof. In another embodiment, the inorganic substance 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 substance 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 performed 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 will become apparent to those skilled in the art upon reading the following detailed description in conjunction with the examples.

Drawings

FIG. 1 is a flow diagram showing the main steps of one embodiment of the present invention.

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

FIG. 3A is a schematic of the experimental set-up 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. 4 is a photograph of an exemplary sample.

Detailed Description

I. Definition of

As used herein, the term "reclaimed 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 the material that is produced after the end consumer uses the material in a consumer product or product.

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

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

As used herein, the term "fluid solvent" refers to a substance that can exist in a liquid state under specific 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. Furthermore, in some embodiments of the present invention, the term "fluid solvent" may also apply to a substance that is at, near, or above the critical temperature and critical pressure (critical point) of the substance. It is well known to those of ordinary skill in the art that a substance above the critical point of the substance is referred to as a "supercritical fluid," which does not have the typical physical properties (i.e., density) of a liquid.

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

equation 1

ΔG_mix＝ΔH_m-TΔS_mix

Wherein Δ G_mixChange in Gibbs free energy for mixing of solute with solvent, Δ H_mixFor mixed enthalpy change, T is absolute temperature, and Δ S_mixIs the entropy of the mixture. To maintain a stable solution of solute in the solvent, the gibbs free energy must be negative and minimal. Thus, any combination of solute and solvent that minimizes the negative gibbs free energy at the appropriate temperature and pressure may be used in the present invention.

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

As used herein, the term "standard vaporization enthalpy change" refers to the change in enthalpy required to convert a specified quantity 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. The polymer solution may contain undissolved matter and thus the polymer solution may also be a "slurry" of undissolved matter suspended in a solution of polymer dissolved in a solvent.

As used herein, the terms "precipitate" and "settle" refer to the tendency of particles within a suspension to separate from a liquid in response to forces acting on the particles (typically gravity).

As used herein, the term "suspended contaminants" refers to unwanted or undesirable components present throughout the media body of the heterogeneous mixture.

As used herein, the term "solid medium" refers to a substance that exists in a solid state under conditions of use. The solid medium may be crystalline, semi-crystalline or amorphous. The solid medium may be granular and may be supplied in different shapes (i.e., spheres, cylinders, pellets, etc.). If the solid medium is particulate, the particle size and particle size distribution of the solid medium may 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 Woven mesh Test Screen Cloth and Test Sieves (Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves)". The solid medium may also be a non-woven fibrous mat or a woven textile.

As used herein, the term "purer polymer solution" refers to a polymer solution having 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 an independently immiscible liquid phase. The driving force or forces for extraction are described by the theory of distribution.

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

As used herein, the term "virgin" refers to polymers that are substantially free of contaminants, pigment-free, odorless, homogeneous, and similar in character to virgin polymers.

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

As used herein, the term "major polyethylene copolymer" refers to a copolymer having greater than 70 mol% ethylene repeat units.

As used herein, any reference to international units of pressure (e.g., MPa) refers to gauge pressure.

Process for purifying contaminated polymers

Surprisingly, it has been found that certain fluid solvents, which in preferred embodiments exhibit temperature and pressure dependent solubility for polymers, are useful when used in relatively simple processesIn the purification of contaminated polymers, especially regenerated or recycled polymers, to near-original quality. The method is illustrated in fig. 1 and comprises: 1) obtaining the regenerated polymer (step a in FIG. 1), then 2) at the extraction temperature (T)_E) And extraction pressure (P)_E) The polymer is then extracted with a fluid solvent (step b in FIG. 1), then 3) at the dissolution temperature (T)_D) And dissolution pressure (P)_D) The polymer is dissolved in a fluid solvent (step c in fig. 1), then 4) at a dissolution temperature (T)_D) And dissolution pressure (P)_D) The polymer solution is precipitated (step d in FIG. 1), then 5) at the dissolution temperature (T)_D) And dissolution pressure (P)_D) The dissolved polymer solution is then contacted with a solid medium (step e in fig. 1) and the polymer is then separated from the fluid solvent (step f in fig. 1).

In one embodiment of the invention, the purified polymer derivable from post-consumer waste streams is substantially free of contaminants, free of pigments, odorless, homogeneous and similar in character to virgin polymer. Furthermore, in a preferred embodiment, the physical characteristics of the fluid solvent of the present invention may enable a more energy efficient process for separating the fluid solvent from the purified polymer.

Recycled polymers

In one embodiment of the present invention, a method for purifying a reclaimed polymer comprises obtaining a reclaimed polymer. For the purposes of the present invention, reclaimed polymers are derived from post-consumer, post-industrial, post-commercial, and/or other specialty waste streams. For example, post-consumer waste polymer may be derived from a roadside recycling stream, where the end consumer places used polymer from packaging and products into designated trash bins for collection by waste handlers or recycling personnel. Post-consumer waste polymer can also originate from in-store "recycling" programs, where the consumer brings the waste polymer into the store and places the waste polymer into designated collection bins. An example of post-industrial waste polymer may be waste polymer generated during the manufacture or shipment of goods or products collected by the manufacturer as unusable material (i.e., trim waste, out of specification material, start-up waste). An example of waste polymers from a particular waste stream may be waste polymers derived from the recycling of electronic waste (also referred to as "e-waste"). Another example of waste polymer from a particular waste stream may be recycled waste polymer from an automobile. Another example of waste polymer from a particular waste stream may be waste polymer derived from the recycling of used carpet and textiles.

For the purposes of the present invention, recycled polymers are homogeneous compositions of a single polymer or mixtures of several different polymers. Non-limiting examples of reclaimed 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 one of ordinary skill in the art.

The reclaimed polymer 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 a final article form. Non-limiting examples of pigments are organic pigments such as copper phthalocyanine, inorganic pigments such as titanium dioxide, and other pigments that may be apparent to one of ordinary skill in the art. One non-limiting example of an organic dye is basic yellow 51. Non-limiting examples of processing aids are antistatic agents such as glyceryl 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(s)

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

The selection of an appropriate solvent or solvent mixture will depend on which reclaimed polymer or polymer mixture is being purified by the present invention. In addition, the choice of the polymer to be purified and the corresponding fluid solvent used will determine the temperature and pressure ranges for performing the steps of the invention. A summary of the phase behavior of polymers in solvents of the type described in the present invention is provided in the following references: McHugh et al (1999) chem.Rev.99: 565-602.

Extraction of

In one embodiment of the invention, a method for purifying reclaimed polymers includes contacting reclaimed polymers with a fluid solvent at a temperature and a pressure, wherein the polymer is substantially insoluble in the fluid solvent. While not wishing to be bound by any theory, applicants believe that the solubility associated with temperature and pressure may be controlled in a manner that prevents the fluid solvent from completely dissolving the polymer, however, the fluid solvent may diffuse into the polymer and extract any extractable contaminants. Extractable contaminants can be residual processing aids added to the polymer, residual product formulations such as perfumes and flavors, dyes that contact the polymer, and any other extractable material that may have been intentionally added or unintentionally incorporated into the polymer, for example, during waste collection and subsequent additional waste material accumulation.

In one embodiment, controlled extraction may be accomplished by fixing the temperature of the polymer/fluid solvent system, and then controlling the pressure below the pressure or pressure range at which the polymer dissolves 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 at which the polymer dissolves in the fluid solvent. Temperature and pressure controlled extraction of the polymer with the fluid solvent uses a suitable pressure vessel and may be configured in a manner that allows for continuous extraction of the polymer with the fluid solvent. In one embodiment of the invention, the pressure vessel may be a continuous liquid-liquid extraction column, wherein molten polymer is pumped into one end of the extraction column and fluid solvent is pumped into the same or the 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 invention, the extraction may be performed as a batch process, wherein the reclaimed polymer is fixed in a pressure vessel and the fluid solvent is continuously pumped through the fixed 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 reclaimed polymer. In another embodiment, the fluid containing the extracted contaminants is contacted with the solid medium in a separate step as described in the "purification" section below. In another embodiment, a method for purifying reclaimed polymers includes contacting reclaimed polymers with a fluid solvent at a temperature and pressure wherein the polymer is molten and in a liquid state. In another embodiment, the reclaimed 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 reclaimed polymers includes contacting polyethylene with a fluid solvent at a temperature and pressure wherein the polyethylene remains substantially undissolved. In another embodiment, a process for purifying reclaimed polymers comprises contacting polyethylene with n-butane at a temperature of from about 80 ℃ to about 220 ℃. In another embodiment, a process for purifying reclaimed polymers comprises contacting polyethylene with n-butane at a temperature of from about 100 ℃ to about 200 ℃. In another embodiment, a process for purifying reclaimed polymers comprises contacting polyethylene with n-butane at a temperature of from about 130 ℃ to about 180 ℃. In another embodiment, a process for purifying reclaimed polymers includes contacting polyethylene with n-butane at a pressure of from about 150psig (1.03MPa) to about 6,500psig (44.82 MPa). In another embodiment, a process for purifying reclaimed polymers includes contacting polyethylene with n-butane at a pressure of from about 3,000psig (20.68MPa) to about 6,000psig (41.37 MPa). In another embodiment, a process for purifying reclaimed polymers includes contacting polyethylene with n-butane at a pressure of from about 4,500psig (31.03MPa) to about 5,500psig (37.92 MPa).

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

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

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

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

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

Dissolution

In one embodiment of the invention, a method for purifying reclaimed polymers includes dissolving reclaimed polymers in a fluid solvent at a temperature and a 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 allows thermodynamically favorable dissolution of the reclaimed polymer in the fluid solvent. In addition, the temperature and pressure may 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 process for purifying reclaimed polymers includes dissolving contaminated reclaimed polymer in a solvent that does not dissolve contaminants under the same temperature and pressure conditions. Contaminants may include pigments, fillers, dirt, and other polymers. These contaminants are released from the reclaimed polymer upon dissolution and are then removed from the polymer solution via a subsequent solid-liquid separation step.

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

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

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

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

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

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

Precipitation of

In one embodiment of the invention, the process 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 a fluid solvent. In one embodiment, the settling step causes the undissolved contaminants to experience a force that moves the undissolved contaminants uniformly in the direction of the force. Typically the applied settling force is gravity, but may also be centrifugal, centripetal, or some other force. The amount of force applied and the settling duration will depend on several parameters including, but not limited to: the particle size of the contaminant particles, the density of the fluid or solution, and the viscosity of the fluid or solution. The following equation (equation 2) is a relationship between the aforementioned parameters and the settling velocity, which is a measure of the rate of contaminant precipitation:

equation 2

Where v is the sedimentation velocity, p_pIs the density of the contaminant particles, p_fIs the density of the fluid or solution, g is the acceleration due to the applied force (usually gravity), r is the radius of the contaminant particle, and η is the dynamic viscosity of the fluid or solution. Some of the key parameters that determine solution viscosity are: chemical composition of fluid solvent, molecular weight of polymer dissolved in fluid solvent, fluid solventThe concentration of the dissolved polymer in the agent, the temperature of the fluid solvent solution, and the pressure of the fluid solvent solution.

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

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

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

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

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

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

Purification of

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

In one embodiment of the invention, the solid medium is selected from an inorganic substance, a carbon-based substance, or a mixture thereof. Useful examples of inorganic substances include oxides of silicon, oxides of aluminum, oxides of iron, aluminum silicates, magnesium silicates, amorphous volcanic glasses, 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 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 agitating the solid medium. In another embodiment, the solid media is removed from the purer polymer solution via a solid-liquid separation step. Non-limiting examples of solid-liquid separation steps include filtration, decantation, centrifugation, and sedimentation. In another embodiment of the invention, the contaminated polymer solution is passed through a fixed bed of solid media. In another embodiment of the invention, the fixed bed of solid media is greater than 5cm in height or length. In another embodiment of the invention, the fixed bed of solid media is greater than 10cm in height or length. In another embodiment of the invention, the fixed bed of solid media is greater than 20cm in height or length. In another embodiment of the invention, the solid media is replaced as necessary 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 during the blow-back step by fluidizing the solid medium.

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

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

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

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

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

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

Separation of

In one embodiment of the invention, a process for purifying reclaimed polymers includes separating purer polymer from a fluid solvent at a temperature and pressure wherein the polymer precipitates from solution and is no longer soluble in the fluid solvent. In another embodiment, precipitation of purer polymer from the fluid solvent is accomplished by reducing the pressure at a fixed temperature. In another embodiment, precipitation of purer polymer from the fluid solvent is accomplished by reducing the temperature at a fixed pressure. In another embodiment, precipitation of purer polymer from the fluid solvent is accomplished by raising the temperature at a fixed pressure. In another embodiment, precipitation of purer polymer from the fluid solvent is accomplished by reducing both temperature and pressure. By controlling the temperature and pressure, the solvent can be partially or completely converted from a liquid to a vapor 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. The separation 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, decantation, centrifugation, and sedimentation.

In one embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/fluid solvent solution at a temperature and pressure, wherein the polyethylene precipitates from the solution. In another embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/n-butane solution at a temperature of from about 0 ℃ to about 220 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/n-butane solution at a temperature of from about 50 ℃ to about 175 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/n-butane solution at a temperature of from about 100 ℃ to about 160 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/n-butane solution at a pressure of from about 0psig (0MPa) to about 4,000psig (27.58 MPa). In another embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/n-butane solution at a pressure of from about 50psig (0.34MPa) to about 2,000psig (13.79 MPa). In another embodiment, a process for purifying reclaimed polymers includes separating polyethylene from a polyethylene/n-butane solution at a pressure of from about 75psig (0.52MPa) to about 1,000psig (6.89 MPa).

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

In one embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/fluid solvent solution at a temperature and pressure, wherein the polypropylene precipitates from the solution. In another embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/n-butane solution at a temperature of from about 0 ℃ to about 220 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/n-butane solution at a temperature of from about 100 ℃ to about 200 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/n-butane solution at a temperature of from about 130 ℃ to about 180 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/n-butane solution at a pressure of from about 0psig (0MPa) to about 2,000psig (13.79 MPa). In another embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/n-butane solution at a pressure of from about 50psig (0.34MPa) to about 1,500psig (10.34 MPa). In another embodiment, a process for purifying reclaimed polymers includes separating polypropylene from a polypropylene/n-butane solution at a pressure of from about 75psig (0.52MPa) to about 1,000psig (6.89 MPa).

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

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

In one embodiment, a method for purifying reclaimed polymers includes separating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/fluid solvent solution at a temperature and a pressure, wherein the poly (dimethylsiloxane) precipitates from the solution. In another embodiment, a method for purifying a reclaimed polymer comprises isolating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/n-butane solution at a temperature of about 0 ℃ to about 220 ℃. In another embodiment, a method for purifying reclaimed polymers includes separating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/n-butane solution at a temperature of about 115 ℃ to about 200 ℃. In another embodiment, a method for purifying a reclaimed polymer comprises isolating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/n-butane solution at a temperature of about 120 ℃ to about 180 ℃. In another embodiment, a process for purifying reclaimed polymers includes separating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/n-butane solution at a pressure of about 0psig (0MPa) to about 1,500psig (10.34 MPa). In another embodiment, a process for purifying reclaimed polymers includes separating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/n-butane solution at a pressure of about 50psig (0.34MPa) to about 1,000psig (6.89 MPa). In another embodiment, a process for purifying reclaimed polymers includes separating poly (dimethylsiloxane) from a poly (dimethylsiloxane)/n-butane solution at a pressure of about 75psig (0.52MPa) to about 500psig (3.45 MPa).

III test method

The test methods described herein are used to measure the effectiveness of various methods of purifying polymers. In particular, the method demonstrates the effectiveness of a given purification method in: improving color and translucency/clarity (i.e., making the color and opacity of the reclaimed polymer closer to that of the unpigmented virgin polymer), reducing or eliminating elemental contamination (i.e., removing heavy metals), reducing or eliminating non-flammable contaminants (i.e., inorganic fillers), reducing or eliminating volatile compounds (especially volatile compounds that contribute to the malodor of the reclaimed polymer), and reducing or eliminating polymer contamination (i.e., polyethylene contamination in polypropylene).

Color and opacity measurement：

The color and opacity/translucency of a polymer are important parameters in determining whether a polymer is capable of achieving the desired visual aesthetics of an article made from the polymer. Reclaimed polymers, especially those derived from post-consumer sources, are often dark and opaque due to residual pigments, fillers, and other contaminants. Thus, color and opacity measurements are important parameters in determining the effectiveness of the process for purifying polymers.

Prior to color measurement, a sample of polymer powder or pellets was compression molded into a square specimen (with rounded corners) 30mm wide by 30mm long by 1mm thick. The powder samples were first densified at room temperature (about 20 ℃ to 23 ℃) by cold pressing the powder into sheets using clean, unused aluminum foil as a contact barrier between stainless steel platens. Approximately 0.85g of cold pressed powder or pellets were then pressed into test specimens on C-type Carver Press (Carver, Inc., Wabash, IN 46992-. The sample was heated for 5 minutes before applying the 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 molded stack is then removed and placed between two thick flat sheet metal fins for cooling. The aluminum foil contact barrier layer was then peeled from the sample and discarded. The flash around the sample on at least one side is peeled to the edge of the mold and the sample is then pushed through the form. Each specimen was visually evaluated for void/bubble defects, and color measurement was performed using only a sample having no defects in the color measurement area (0.7 ″ (17.78mm) 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 the brightness of the sample, where L0 corresponds to the darkest black sample and L100 corresponds to the brightest white sample. The dimension a is a measure of the red or green color of the sample, with positive values a corresponding to red and negative values a corresponding to green. The dimension b is a measure of the blue or yellow color of the sample, with positive values b corresponding to yellow and negative values b corresponding to blue. The L a b values were measured on a Hunter Lab-type LabScan XE spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA 20190-. The spectrophotometer was constructed with D65 as the standard illuminant, a viewing angle of 10 °, an area diameter viewing angle of 1.75"(44.45mm), and a port diameter of 0.7" (17.78 mm).

The contrast ratio opacity mode was used to determine the opacity of each sample, which is a measure of how much light was transmitted through the sample (i.e., a measure of the translucency of the sample), using the aforementioned HunterLab spectrophotometer. Two measurements were made to determine the opacity of each sample. Measurement of the lightness value Y of the sample with a white backing as background_{White backing}And the brightness value Y of the sample was measured once with a black backing as a background_{Black backing}. Opacity is then calculated from the luminance values using the following equation 3:

equation 3

Elemental analysis：

Many recycled polymers have unacceptably high levels 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 process for purifying a polymer.

Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Preparation of the test solutions: depending on sample availability, n-2 to n-6, approximately 0.25g of sample was combined with 4mL of concentrated nitric acid and 1mL of concentrated hydrofluoric acid (HF). Samples were digested using the Ultrawave microwave digestion protocol which was ramped from 20min to 125 ℃ and 10min to 250 DEG CAnd maintaining at 250 ℃ for 20 min. The digested sample was cooled to room temperature. After addition of 0.25mL of 100ppm Ge and Rh as internal standards, the digested sample was diluted to 50 mL. To assess the accuracy of the measurements, pre-digested admixtures were prepared by doping virgin polymer. The samples doped with virgin polymer were weighed using the same procedure described above, and doped with appropriate amounts of each elemental standard of interest, which included the following: na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb. Admixtures were prepared at two different levels: "Low level admixtures" and "high level admixtures". Each spike was prepared in triplicate. In addition to the incorporation of virgin polymer, billets were also incorporated to confirm that no errors occurred during pipetting and to track recovery throughout the process. Samples doped with the billets were also prepared in triplicate at two different levels and processed in the same manner as the doped virgin polymer and test samples. The 9-point calibration curve was prepared by preparing solutions containing Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb at 0.05ppb, 0.1ppb, 0.5ppb, 1ppb, 5ppb, 10ppb, 50ppb, 100ppb, and 500 ppb. All calibration standards were prepared using 4mL of concentrated nitric acid and 1mL of concentrated HF by diluting the pure standard reference solution with 0.25mL of 100ppm Ge and Rh as internal standards. The prepared standards, test samples and spiked test samples were analyzed using Agilent's 8800ICP-QQQMS, optimized according to manufacturer recommendations. The monitored m/z for each analyte and the collision cell gas used for 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(ii) a Ni, 60 m/z; no gas is generated; cu, 65m/z, no gas; zn, 64m/z, He; cd, 112 m/z; h₂(ii) a Pb, the total number is more than or equal to 206, 207 is more than or equal to 207, 208 is more than or equal to 208m/z, and no gas exists; ge, 72m/z, all modes; rh, 103m/z, all modes. Ge was used as internal standard for all elements<103m/z, and Rh for all elements>103m/z。

Residual ash content：

Many recycled polymers contain various fillers such as calcium carbonate, talc and glass fibers. While useful in the original application of the reclaimed polymer, these fillers alter the physical properties of the polymer in a manner that may be undesirable for the next application of the reclaimed polymer. Therefore, measuring the amount of filler is important in determining the effectiveness of the process for purifying a polymer.

Thermogravimetric analysis (TGA) was performed to quantify the amount of non-combustible material (sometimes also referred to as ash content) in the sample. Approximately 5 to 15mg of sample was loaded onto a platinum sample tray and heated to 700 ℃ in a TA Instruments model Q500 TGA instrument at a rate of 20 ℃/min in an air atmosphere. The sample was kept isothermal for 10min at 700 ℃. After isothermal holding, the residue mass percentage was measured at 700 ℃.

Odor analysis：

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

5 is very strong

4 is strong

3-medium

2-Weak to moderate

1 is weak

0-no smell

Polymer contamination analysis：

Many recycled polymers, especially recycled polymers derived from mixed streams, may contain undesirable polymer contaminants. Without wishing to be bound by any theory, polymer contamination (e.g., polyethylene contamination in polypropylene) may affect the physical properties of the polymer due to the presence of heterogeneous phases and the resulting weak interface. 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 process for purifying a polymer.

Evaluation of moieties using Differential Scanning Calorimetry (DSC)Contamination of the crystalline polymer. For example, to measure the amount of polyethylene contamination in polypropylene, 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.% and 10 wt.% are used

HB5502F HDPE (Formosa Plastics Corporation, USA) A set of five polypropylene/polyethylene blends was prepared in Pro-fax 6331 polypropylene (LyondellBasell Industries Holdings, B.V.). Approximately 5 to 15mg of each sample was sealed in an aluminum DSC pan and analyzed on a TA Instruments model Q2000 DSC using the following method:

1. equilibrating at 30.00 deg.C

2. Ramp up to 200.00 deg.C at 20.00 deg.C/min

3. Marking the end of cycle 0

4. The temperature is reduced to 30.00 ℃ in a gradient of 20.00 ℃/min

5. Marking the end of cycle 1

6. Ramp up to 200.00 deg.C at 20.00 deg.C/min

7. Marking the end of cycle 2

8. The temperature is reduced to 30.00 ℃ in a gradient of 20.00 ℃/min

9. Marking the end of cycle 3

10. Ramping up to 200.00 deg.C at 5.00 deg.C/min

11. Marking the end of cycle 4

The melting enthalpy of the HDPE peak at about 128 ℃ for each known HDPE content sample was calculated using a 5.00 ℃/min DSC thermogram. The linear calibration curve shown in figure 2 is established via a plot of enthalpy of fusion versus known HDPE concentration (% by weight).

Samples with unknown PE content were analyzed using the same DSC equipment and method described above. The PE content was calculated using the calibration curve described above. The particular HDPE used to generate the calibration curve will more likely have a different crystallinity than the polyethylene (or polyethylene blend) contamination that may be present in the reclaimed polymer sample. The crystallinity can independently influence the measured enthalpy of fusion of the polyethylene and thus the resulting calculation of the polyethylene content. However, the DSC test method described herein is intended as a relative measure of effectiveness for comparing different methods for purifying polymers, and is not meant to be a strict quantification of polyethylene content in a polymer blend. Although the above method describes the measurement of polyethylene contamination in polypropylene, the method is applicable to the measurement of peaks in other semi-crystalline polymers and DSC thermograms using different temperature ranges. Furthermore, alternative methods such as Nuclear Magnetic Resonance (NMR) spectroscopy may also be used to measure the amount of both semi-crystalline and amorphous polymer contamination in a sample.

Examples

The following examples further describe and demonstrate embodiments within the scope of the present invention. These examples are given solely for the purpose of illustration and are not to be construed as limitations of the present invention, as many variations thereof are possible without departing from the spirit and scope of the invention.

Example 1

Samples derived from post-consumer recycled polypropylene color blended flakes were derived from recycled resin suppliers. Post-consumer recycled polypropylene originates from the united states and canada. The directly useable color blend flakes were homogenized via mixing on a Century/W & P ZSK30 twin screw extruder equipped with two 30mm universal screws, each with standard mixing and conveying elements. The screw speed was about 50rpm, the throughput of the feeder was about 20 pounds per hour (9.07kg per hour), and the barrel temperature ranged from about 210 ℃ at the die to about 150 ℃ at the feed throat. The gray strands leaving the extruder were cooled in a room temperature water bath, dried with air, and chopped into pellets.

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

Pellets and corresponding square samples appear dark gray as indicated by the la b values of the square samples. The opacity of the samples averaged about 100% opaque (i.e., not translucent). The photograph of the square sample is shown in fig. 4 as example 1. As shown in fig. 4, the sample is dark in color and lacks translucency.

This example serves as a representative baseline for heavy metal contamination found in polypropylene derived from post-consumer recycle. When compared to the other examples, it was found that the heavy metal contamination is much greater in the polypropylene that can be used directly from post-consumer recycling.

The samples of example 1 had ash content values averaging about 1.2117 wt%, which also served as a baseline for the amount of non-combustible materials typically present in polypropylene derived from post-consumer recycle.

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

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

Example 2

The sample of post-consumer recycled polypropylene color-blended sheet described in example 1 was processed using the experimental setup shown in fig. 3A and 3B and the following procedure:

1. 286g of the mixed color flake was loaded into a 7.57 liter autoclave, model Parr Instrument Company 4552M, 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 ℃ and a fluid pressure of 900psig (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 ℃ and 900psig (6.21MPa) for 10 min.

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

c. One vessel volume of n-butane was injected into the sample collection flask via an autoclave at 140 ℃ and 900psig (6.21 MPa).

d. The above extraction procedure was repeated four times or more.

e. The material collected for all extraction cycles is labeled "fraction 1".

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

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

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

c. Stirring was then stopped and the solution was allowed to settle at 140 ℃ and 1800psig (6.21MPa) for 30 min.

d. After settling, the autoclave solution was removed by displacement with pressurized nitrogen (pre-equilibrated to 140 ℃ and 1800 psig). The solution leaving the autoclave through the dip tube was then passed through two columns of heat traced solid media. Each column had an ID of 0.68"(1.73cm) and a length of about 9.5" (24.13 cm). The first column contained about 21g of 8 mesh to 16 mesh bleaching earth (Jaxon Filtration, JF 752-8/16, USA) premixed in a beaker with about 21g of 30 mesh to 60 mesh bleaching earth (Jaxon Filtration, JF 752-. The second column contained about 21g of silica gel (silica ultrapure silica gel, SiliaFlash GE60, Parc-Technologies, USA) premixed in a beaker with about 21g of alumina (activated alumina, Selexsorb CDX, 7X 14, BASF, USA). The fluid stream exiting the bottom of the second pressure vessel was depressurized through an expansion valve into a sidearm 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 was collected as a fraction in the flask. Each fraction contained about 30g of material and was labeled sequentially starting with "fraction 2". Fractions were collected until no more material elution into the flask could be observed.

5. After all samples were collected, the autoclave was equilibrated 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 procedure 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. The photograph of the square sample prepared from fraction 3 is shown in fig. 4 as example 2. For reference, virgin polypropylene is shown in fig. 4 as example 4. As shown in fig. 4, the sample is transparent and comparable in color and translucency to virgin polypropylene. The values of la b show that the square samples are essentially colorless and show a significant color improvement over the square samples of example 1 (i.e., the post-consumer polypropylene that can be used directly). The L values of the square samples from fraction 3 of example 2 averaged 80.44, which was greatly improved when compared to the L values of the square samples of example 1, which averaged 39.76. The opacity of the square specimens from fraction 3 of example 2 averaged 10.30% opaque (i.e., about 90% translucent), which was also greatly improved when compared to the opacity value of the square specimens of example 1, which averaged about 100% opaque.

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 sample from fraction 3 of example 2 averaged only 4,100ppb, while the sodium concentration in the sample of example 1 averaged 136,000ppb (a reduction of about 97%). All other element concentrations measured for the sample from fraction 3 of example 2 were reduced by 77% to 100% relative to the sample of example 1.

The samples from fraction 3 of example 2 had ash content values averaging about 0.3874 wt%, which was significantly lower than the ash content values of the samples of example 1 averaging 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 points being the strongest), which was greatly improved when compared to the odor intensity of the sample of example 1, which had an odor intensity of 3.75. 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 sample from fraction 3 of example 2 had an average polyethylene content value of about 1.1 wt%, which was greatly improved when compared to the polyethylene content of the sample of example 1, which averaged about 5.5 wt%.

Example 3

6. 173g of the mixed color flake was loaded into a 7.57 liter autoclave, model Parr Instrument Company 4552M, 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 ℃ and a fluid pressure of 900psig (6.21 MPa).

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

f. the system was stirred at 140 ℃ and 900psig (6.21MPa) for 10 min.

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

h. One vessel volume of n-butane was injected into the sample collection flask via an autoclave at 140 ℃ and 900psig (6.21 MPa).

i. The above extraction procedure was repeated four times or more.

j. Samples collected for each extraction cycle are labeled "fraction 1" to "fraction 5" in turn.

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

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

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

g. Stirring was then stopped and the solution was allowed to settle at 140 ℃ and 1800psig (6.21MPa) for 60 min.

h. After settling, the solution of the autoclave was removed by displacement with pressurized n-butane (pre-equilibrated to 140 ℃ and 1800 psig). The solution leaving the autoclave through the dip tube was then passed through two columns of heat traced solid media. Each column had an ID of 0.68"(1.73cm) and a length of about 9.5" (24.13 cm). In this example, both columns are empty and do not contain any solid media. The fluid stream exiting the bottom of the second pressure vessel was depressurized through an expansion valve into a sidearm 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 was collected as a fraction in the flask. Each fraction contained about 30g of material and was labeled sequentially starting with "fraction 6". Fractions were collected until no more material elution into the flask could be observed.

10. After all samples were collected, the autoclave was equilibrated 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 procedure 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 test specimens, the samples appeared yellow in appearance. The photograph of the square sample is shown in fig. 4 as example 3. As shown in fig. 4, the color and translucency of the sample of example 3 was improved relative to the sample of example 1, but not comparable to virgin polypropylene (shown in fig. 4 as example 4). Even in the absence of the solid medium contacting step, the la b values show that the square samples from fraction 6 of example 3 are improved in color relative to the samples of example 1 (i.e., the polypropylene from post-consumer that can be used directly). The L values of the square samples from fraction 6 of example 3 averaged 72.41, which was improved when compared to the L values of the square samples of example 1, which averaged 39.76. The opacity of the square specimens from fraction 6 of example 3 averaged 35.25% opaque, which was also improved when compared to the opacity value of the square specimens of example 1, which averaged about 100% opaque.

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 sample from fraction 6 of example 3 averaged only 16,400ppb, while the sodium concentration in the sample of example 1 averaged 136,000ppb (a reduction of about 88%). All other element concentrations measured for the sample from fraction 6 of example 3 were reduced by 82% to 100% relative to the sample of example 1.

The samples from fraction 6 of example 3 had ash content values averaging about 0.2292 wt%, which was significantly lower than the ash content values of the samples of example 1 averaging 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 points being strongest), which was greatly improved when compared to the odor intensity of the sample of example 1, which had an odor intensity of 3.75. 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 sample from fraction 6 of example 3 had an average polyethylene content value of about 1.0 wt%, which was greatly improved when compared to the polyethylene content of the sample of example 1, which averaged about 5.5 wt%.

Example 4 comparison sample of virgin Polypropylene

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 test specimens according to the process described herein. The values la b of the samples made from the original PP averaged 85.13 ± 0.18, -0.71 ± 0.01, and 2.27 ± 0.02, respectively. The square specimens 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. Samples of virgin polypropylene had ash content values averaging about 0.3031 wt%. Pellets of virgin PP have an odor intensity of 0.5 on a 5 point scale (5 points being strongest) and have an odor described as "plastic". No polyethylene was detected in the samples of virgin propylene.

Table 1: color, contaminant and odor removal of examples 1 through 4

Each document cited herein, including any cross-referenced or related patent or patent application, is hereby incorporated by reference in its entirety unless expressly excluded or otherwise limited.

The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, or that it teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document 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 document 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 that are within the scope of this invention.

Claims

1. A method for purifying a reclaimed polymer selected from the group consisting of polystyrene, poly (dimethylsiloxane), polypropylene homopolymer or major polypropylene copolymer, polyethylene homopolymer or major polyethylene copolymer, the method comprising:

a. obtaining the reclaimed polymer, wherein the reclaimed polymer is selected from the group consisting of post consumer polymers, post industrial polymers, and combinations thereof;

b. contacting the reclaimed polymer with a first fluid solvent having a normal boiling point of less than 70 ℃ at a temperature of from 80 ℃ to 220 ℃ and a pressure of from 150psig (1.03MPa) to 15,000psig (103.42MPa), wherein the polymer is substantially insoluble in the first fluid solvent, to produce an extracted reclaimed polymer;

c. dissolving the extracted reclaimed polymer in a solvent selected from the group consisting of the first fluid solvent, a second fluid solvent, and mixtures thereof at a temperature of from 90 ℃ to 220 ℃ and a pressure of from 350psig (2.41MPa) to 20,000psig (137.90MPa) to produce a first solution comprising polymer and suspended contaminants;

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

e. purifying the second solution by contacting the second solution with a solid medium at a temperature of 90 ℃ to 220 ℃ and a pressure of 350psig (2.41MPa) to 20,000psig (137.90MPa) to produce 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 or a different chemical composition than the first fluid solvent.

2. The process of claim 1, wherein the purer polymer is separated from the third solution at a temperature of from 0 ℃ to 220 ℃ and a pressure of from 0psig (0MPa) to 2,000psig (13.79 MPa).

3. The method of claim 1, wherein the reclaimed polymer is dissolved in the fluid solvent or fluid solvent mixture at a concentration of at least 0.5 percent by mass.

4. The method of claim 1, wherein the reclaimed 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 reclaimed 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 reclaimed polymer is dissolved in the fluid solvent or fluid solvent mixture at a mass percent concentration of up to 20%.

7. The method of claim 1, wherein the reclaimed 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 reclaimed polymer is a polymer derived from post-consumer recycle.

9. The method of claim 1, wherein the fluid solvent has a normal boiling point of less than 0 ℃ and greater than-45 ℃ and a normal enthalpy of vaporization of less than +25 kJ/mol.

10. The method of claim 1, wherein the fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof.

11. The method of claim 10, wherein the aliphatic hydrocarbon is selected from C₁-C₆Aliphatic hydrocarbons and mixtures thereof.