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WO2025186410A1 - Procédé - Google Patents

Procédé

Info

Publication number
WO2025186410A1
WO2025186410A1 PCT/EP2025/056196 EP2025056196W WO2025186410A1 WO 2025186410 A1 WO2025186410 A1 WO 2025186410A1 EP 2025056196 W EP2025056196 W EP 2025056196W WO 2025186410 A1 WO2025186410 A1 WO 2025186410A1
Authority
WO
WIPO (PCT)
Prior art keywords
water
paos
polymer
solution
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/056196
Other languages
English (en)
Other versions
WO2025186410A8 (fr
Inventor
Corentin Dubois
Florent MINETTE
Jean-Philippe Dumont
Loris PANARISI
Eric Romers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Inovyn Europe Ltd
Original Assignee
Inovyn Europe Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Inovyn Europe Ltd filed Critical Inovyn Europe Ltd
Publication of WO2025186410A1 publication Critical patent/WO2025186410A1/fr
Publication of WO2025186410A8 publication Critical patent/WO2025186410A8/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/04—Recovery or working-up of waste materials of polymers
    • C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
    • C08J11/08—Recovery or working-up of waste materials of polymers without chemical reactions using selective solvents for polymer components
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08J2327/06—Homopolymers or copolymers of vinyl chloride
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

  • the present invention relates to a process for recycling of polymers, and in particular of polyvinyl chloride (PVC) polymers.
  • PVC polyvinyl chloride
  • PVC polyvinyl chloride
  • additives including mineral fillers, thermal stabilisers and plasticisers.
  • thermal stabilisers based on lead and cadmium, and plasticisers such as di (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and benzyl butyl phthalate (BBP), which were historically used are now subject to restrictions on their use in “new” PVC but also their presence in recycled PVC.
  • DEHP di (2-ethylhexyl) phthalate
  • DBP dibutyl phthalate
  • BBP benzyl butyl phthalate
  • US 7056956 describes a process for recycling a plastic (i.e. a polymer) which comprises dissolution and precipitation of the plastic.
  • a plastic i.e. a polymer
  • This patent describes the use of a “phase separating agent” in addition to the solvent for the plastic, which phase separating agent improves the dissolution of the plastic in the solvent.
  • the phase separating agent is removed, along with the solvent, to form precipitated plastic.
  • US 7056956 exemplifies use of methyl ethyl ketone as the solvent, n-hexane as the phase separating agent and PVC as the plastic, and uses steam and liquid water to heat and cause vaporisation of the phase separating agent and solvent.
  • WO 2009/037316 relates to a similar process.
  • This document exemplifies use of methyl ethyl ketone as the solvent, iso-hexane as the phase separating agent and PVC as the plastic, and uses steam and liquid water to heat and cause vaporisation of the phase separating agent and solvent (referred to in this document as a “polar aprotic organic solvent” or “PAOS”).
  • PAOS polar aprotic organic solvent
  • This document further teaches the addition of an alcohol, such as isopropanol, to the system.
  • This document discusses that sufficient steam and water must be introduced to remove substantially all of the phase separating agent (PSA) and solvent (PAOS). Whilst the above processes are effective for dissolution and precipitation of the plastic, specifically PVC, they suffer from requiring a significant quantity of steam and hot liquid water which must be introduced to remove all of the PSA and solvent/PAOS.
  • polymer materials particularly PVC materials
  • plasticisers and/or other liquid additives which are also soluble in the solvent.
  • These additives are then reprecipitated with the polymer and hence remain in the recovered polymer material.
  • a number of such additives used historically have been subsequently subject to restrictions on their use.
  • plasticisers such as di (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and benzyl butyl phthalate (BBP), which were historically used in PVC are now subject to restrictions on their use in “new” PVC but also their presence in recycled PVC.
  • DEHP di (2-ethylhexyl) phthalate
  • DBP dibutyl phthalate
  • BBP benzyl butyl phthalate
  • the present invention relates generally to recycling of polymers.
  • the solution of polymer in step (a) is typically obtained by dissolving a polymer to be recycled, or a composition or mixture comprising a polymer to be recycled, in the solvent mixture.
  • the polymer to be recycled may initially be mixed with or comprise insoluble components, the nature of which will depend on the previous application of the polymer. Examples can include, for example, fibres and fillers.
  • the solution obtained by dissolving the polymer in the solvent mixture may be filtered to remove insoluble components prior to step (a) of the present invention.
  • Such dissolution and filtration may be performed by any conventional techniques. (An example of the dissolution and filtration of a PVC cable scrap comprising fillers is described in WO 2009/037316 for example.)
  • the present invention may be applied to any suitable polymer.
  • suitable polymers include polymers of ethylene (PE) or of propylene (PP), polymers derived from styrene monomers, acrylic monomers and halogenated ethylenically unsaturated monomers or copolymers of ethylene and vinyl alcohol (EVOH) or vinyl acetate (EVA, EBA, etc.).
  • the present invention is directed to recycling of PVC, and the polymer is therefore a PVC polymer, or to polymers which have a solubility parameter close to that of PVC (such as PMMA (polymethyl methacrylate), PVA (polyvinyl alcohol) and PUR (polyurethane)).
  • PVC polymethyl methacrylate
  • PVA polyvinyl alcohol
  • PUR polyurethane
  • close is understood to define solubility parameters (expressed in MPa 1/2 ) that do not generally differ from one another by more than around 1.8.
  • the polymer is PVC.
  • the PVC may be a homopolymer or a copolymer, for example with vinyl acetate or an alkyl (meth)acrylate as comonomer.
  • the present invention is based on the surprising finding that the polymer initially present in the solution of step (a) can be largely or completely precipitated by removal of the phase separating agent (PSA) even if the majority of the PAOS is still present.
  • PSA phase separating agent
  • the solvent mixture for the dissolution comprises water, the PAOS and the PSA.
  • the polymer is soluble in the PAOS “alone”, but its solubility is decreased by the presence of water.
  • water above about 10wt% in a mixture which comprises just the water and PAOS
  • the polymer is largely insoluble.
  • the solubility of the polymer is increased in an initial solvent mixture comprising PAOS, PSA and water the polymer is soluble.
  • the PSA is removed from this mixture the polymer is caused to precipitate.
  • the removal of the PSA is achieved by addition of further water, either by addition of liquid water or steam or a combination thereof.
  • Addition of water at least partially via addition of steam is preferred. This has the dual advantage of providing heat for stripping of the PSA but also increasing the water content of the remaining solution/liquid phase, which assists in further precipitation of the polymer material.
  • the solvent mixture in step (a), which is usually the solvent mixture used to dissolve the polymer in an earlier step, comprises less than 10% by weight, and preferably less than 6% by weight of water.
  • the major component of the solvent mixture is PAOS typically found in a weight ratio, relative to the PSA of 4: 1 to 8: 1.
  • the solvent mixture may, and preferably does, also comprise an alcohol, such as described in WO 2009/037316.
  • PAOS PAOS
  • PSA PAOS
  • the PAOS is a compound which forms an azeotrope with water
  • the PSA is an apolar organic compound that is miscible with the PAOS and immiscible with water
  • the boiling point of the PSA is below that of the water/PAOS azeotrope.
  • Preferred PAOS include, dimethyl sulphoxide (DMSO), tetrahydrofuran (THF) and substituted tetrahydrofurans, such as 2-methyltetrahydrofuran (2Me-THF) and ketones.
  • DMSO dimethyl sulphoxide
  • THF tetrahydrofuran
  • 2Me-THF substituted tetrahydrofurans
  • ketones such as diethylketone (DEK) or, most preferably, methylethylketone (MEK).
  • Preferred PSA’s are alkanes having 5 to 7 carbons atoms, more preferably hexanes, such as n-hexane and iso-hexane, and with iso-hexane being most preferred.
  • Preferred alcohols are tert-butyl alcohol (2-methyl-2-propanol) and iso-propanol, with iso-propanol being most preferred.
  • a preferred solvent mixture for the solution of step (a) is a mixture of a ketone (as the PAOS), an alkane (as the PSA), an alcohol and water, for example a mixture of methyl ethyl ketone (MEK) with hexane, iso-propanol and water.
  • a particularly solvent mixture in the solution of step (a) comprises, and preferably consists essentially of, between 2% and 8% by weight of alcohol, preferably iso-propanol, between 13% and 17% by weight of alkane, preferably iso-hexane, between 3% and 6% by weight of water, and between 69% and 82% by weight of a ketone, preferably methyl ethyl ketone.
  • the solution of step (a) is typically, and preferably, a solution obtained by an earlier step of dissolution of the polymer in the solvent mixture.
  • the solution may have been treated, after dissolution of the polymer, to separate the solution from insoluble components of the initial polymer material to be recycled. It may also have been treated to remove heavy metals, if present, for example using chelating agents.
  • the concentration of polymer in the solution of step (a) is typically at least 5wt%, such as 5 to 20wt%. Concentrations in the range 8 to 14wt%, are preferred.
  • the dissolution may have been performed at an elevated pressure. Where this is the case then the solution obtained in step (a) may also be at elevated pressure, such as from 200 to 500 kPag (2 to 5 barg).
  • step (b) of the present invention at least some of the PSA is removed from the solution to cause precipitation of the polymer and provide a slurry of polymer particles in a liquid phase comprising water and the PAOS.
  • step (b) includes the addition of further water (i.e. further to that already present), in the form of either liquid water or steam, or both. (This may be done in addition to a pressure reduction.) As already noted this has the dual advantage of providing heat for stripping of the PSA but also increasing the water content of the remaining slurry, which assists in further precipitation of the polymer material.
  • a dispersing agent such as a partially hydrolysed polyvinyl acetate (PVA) may be present during this step, either by addition during this step, or by addition to the solution of step (a) prior to this step.
  • PVA polyvinyl acetate
  • step (b) the majority of the PSA should be removed from the solution as provided in step (a).
  • at least 80% by weight of the PSA which is present in the solution provided in step (a) should be removed in this step, preferably at least 90% by weight, such as 95-100% by weight.
  • the slurry obtained in step (b) comprises at least 70% by weight of the PAOS which was in the solution provided in step (a), preferably at least 80% by weight, such as at least 90% by weight.
  • the slurry obtained in step (b) and treated in step (c) comprises less than 20%, preferably less than 10%, of the PSA which was present in the solution of step (a) and at least 80% of the PAOS which was in the solution of step (a).
  • the slurry liquid phase obtained in step (b), including additional water where added typically comprises at least 10wt% water, such as 10-40wt% water, for example 10-25wt% water.
  • the slurry liquid phase preferably comprises at least 55%, such as at least 65% by weight of PAOS.
  • the slurry liquid phase preferably comprises 2% and 10% by weight of alcohol, preferably iso-propanol, between 10% and 40%, such as between 10% and 25%, by weight of water, and between 55% and 85%, such as between 65% and 88%, by weight of PAOS, preferably a ketone, and more preferably methyl ethyl ketone. Residual amounts of the PSA may be present, but the concentration of PSA is generally less than 2.5wt%, such as in the range 0 to 2.5wt%, and more preferably 0 to 1.5wt%.
  • the slurry liquid phase obtained may in fact comprise two phases, one being an aqueous phase and the other being an organic phase.
  • step (b) causes precipitation of the polymer and provides a slurry of polymer particles in a liquid phase comprising the water and the PAOS, and typically also comprising an alcohol.
  • the precipitated polymer is in the form of polymer particles containing residual PAOS and water.
  • the polymer particles comprise absorbed PAOS and water, and may be considered as solvent “swollen”.
  • step (c) of the present invention the slurry is instead treated at this stage by performing a solidliquid separation on the slurry.
  • the solid-liquid separation separates the majority of the PAOS and water present in the slurry, to provide polymer particles comprising residual PAOS and water.
  • the solid-liquid separation separates the majority of the PAOS and water but sufficient of the slurry liquid phase is retained such that the polymer particles comprising residual PAOS and water provided after the solid-liquid separation are still in the form of a concentrated slurry.
  • the concentrated slurry may have a solids concentration, for example, of at least 40wt%, such as at least 50wt% solids by weight of the slurry.
  • the solid-liquid separation separates the vast majority of the PAOS and water, such as at least 90% by weight, preferably at least 95% by weight of the PAOS and water initially present in the slurry liquid phase.
  • sufficient PAOS and water are removed in the solid-liquid separation such that the polymer particles comprising residual PAOS and water provided after the solid-liquid separation are in solids form. (They may be considered as “wet” in the sense that there is residual PAOS and water absorbed in or on the particles, but the polymer particles are no longer in sufficient liquid to form a slurry).
  • the “residual PAOS and water” comprises less than 10% by weight, preferably less than 5% by weight relative to the amount of PAOS and water initially present in the slurry liquid phase.
  • This solid-liquid separation may be performed by any known solid-liquid separation means for separating solids (in this case the polymer particles or a concentrated slurry thereof) from a liquid phase. Examples include settling, centrifuging (spinning), filtering, etc.
  • One preferred solid-liquid separation comprises filtering. This may be any conventional filter, including, for example, a rotary pressure filter, Nutsche filter, Candle filter, etc.
  • a further preferred solid-liquid separation comprises centrifuging by use of a centrifuge, such as a decanter centrifuge. Examples of suitable decanter centrifuges are those produced by Tomoe Engineering Co. Limited, Andritz Separation and GEA.
  • solid-liquid separation is meant a process in which the solids are separated from a liquid phase whilst keeping the liquid phase in a liquid form.
  • the PAOS and water separated in the solid-liquid separation are separated in a liquid form.
  • a single liquid phase product or two or more separate liquid phase products from this step e.g. an aqueous phase product and an organic phase product.
  • a decanter centrifuge for example, can be operated to separate two or more liquid phases of differing densities.
  • step (d) of the present invention the separated polymer particles are treated to remove the residual PAOS and water, and thereby to recover the polymer particles.
  • the polymer particles are mixed with water prior to step (d) of the present invention, to provide a slurry comprising polymer particles in an aqueous phase.
  • the obtained slurry preferably has a solids concentration of at least 20wt%, such as 20- 35wt%. In one preferred embodiment this may be performed using a portion of the water which is initially separated in this step (c).
  • the PAOS and water are generally immiscible, so water/an aqueous phase could be separated by allowing the two phases to separate, such as in a decanter.
  • the polymer particles will be heated, optionally using steam or hot water, to remove the residual PAOS and to provide a slurry of the polymer particles in water (with reduced level, and preferably the substantial absence of PAOS).
  • the particles can then be separated from the water, again using any suitable separation means for separating a solid from a liquid phase, such as those already described, and then dried to remove residual water.
  • the polymer particles with residual PAOS and water may be first washed with a solvent wash stream.
  • a “clean” mixture comprising the PAOS and water may be used as a solvent wash stream.
  • the PAOS and water initially present may comprise small amounts of PSA or, as will be discussed below, plasticisers and/or other soluble liquid additives, and it may be desirable to wash with a “clean” solvent stream to separate these first.
  • wash steps may be performed if desired.
  • the obtained, “washed” particles can then be treated, for example heated with steam or hot water to remove any organic components of the solvent wash stream or streams and leave polymer particles in water which can be separated and dried as already described.
  • step (c) of the present invention results in one or more liquid phase products comprising the majority of the PAOS and water which was present in the slurry.
  • a single liquid phase product comprising PAOS and water
  • the liquid product is preferably treated to recover the PAOS or a mixture comprising PAOS and water but with a lower level of water.
  • the PAOS and water are generally immiscible and hence, if left to settle, form two phases, comprising an aqueous phase and an organic (PAOS) phase.
  • PAOS organic
  • the PAOS may be separated from the aqueous phase by decantation or similar.
  • the separated PAOS may, if desired, be treated to further purify, for example by distillation or by drying to remove residual water.
  • PAOS may be recovered from any products which comprise PAOS. Similar techniques to those noted above can be applied. For example, for liquid phase products which comprise PAOS and water they can be left to settle, and the PAOS may be separated from the aqueous phase by decantation or similar. Any product from such steps, or any products which are already essentially or largely PAOS as recovered, may, if desired, be treated to further purify, for example by distillation or drying as already noted.
  • recovered PAOS can be used for dissolution of further polymer to form a further solution for step (a). All or part could also be used as part of a washing solvent stream in step (d) where this step is performed.
  • This slurry liquid phase may, as described further below, also comprise plasticisers and/or other soluble liquid additives which were present in the original polymer. During the solid-liquid separation these additives are separated with the liquid phase, and in particular with the organic (PAOS) phase.
  • the PAOS may be treated to separate the plasticisers so that the PAOS can be recycled and reused in the present invention.
  • the separated plasticisers may comprise phthalate plasticisers but also other non-phthalate plasticisers.
  • the separated plasticisers may be purified, e.g. by hydrogenation, so that they can be reused as plasticisers under EU REACH or similar regulations in other jurisdictions and/or other applications.
  • a particular advantage of the present invention is that it is more efficient from an energy use perspective, and in particular compared to the previously operated processes.
  • the previously operated processes it was necessary to provide sufficient steam and liquid water to remove not just the PSA present in the solution but also the PAOS.
  • the latter of course, not only typically having a higher boiling point (either per se or as an azeotrope with water) than the PSA, but also formed the major part by weight of the solution.
  • the process requires a much lower “energy input”.
  • to remove the PSA in step (b) of the present invention clearly requires much less energy input than removing all of the PSA and all of the PAOS (in the form of an azeotrope, so also a lot of water is both added and removed to remove the PAOS).
  • the present invention does contemplate also providing some energy in other steps, but typically the energy requirements are much lower than savings made by not having to remove the PAOS using steam and liquid water.
  • the amount of energy, for example in the form of liquid water or steam, required to separate residual PAOS and water from the polymer particles in step (d) is much less than required compared to the previously operated process i.e.
  • step (c) the amount of energy required for treatment and recovery of PAOS separated in step (c) to make this suitable for recycle is generally relatively low because the PAOS can be readily separated from the majority of the water before it needs to be treated.
  • the amount of steam required for this is much less than required for the removal of the PSA and PAOS as noted above. In terms of the actual amount of steam required for this step, this generally depends on the amount of PS A it is necessary to remove. This can itself be dependent on the initial polymer mixture to be subject to recycling, and in particular on the amount of solvent necessary to dissolve the polymer.
  • the amount of steam injected is less than 2 kg steam per kg of polymer present, such as less than 1.5 kg steam per kg of polymer present. In embodiments, the amount of steam injected is less than 1 kg steam per kg of polymer present. (This is particularly the case where the polymer is a PVC polymer and the PSA is an alkane having 5 to 7 carbons atoms, for example.)
  • the total amount of steam for the removal of PSA from the solution in step (b) and treating the polymer particles to remove the residual PAOS and water in step (d) is less than or equal to 5 kg steam per kg of polymer, such as less than or equal to 4 kg steam per kg of polymer, or even less than or equal to 3 kg steam per kg of polymer.
  • the polymer is a PVC polymer
  • the PSA is an alkane having 5 to 7 carbons atoms
  • the PAOS is a ketone, for example.
  • the present invention is much less energy intensive.
  • the recovered polymer particles from step (d) of the present invention are, in terms of particle size and shape, generally the same or similar to that obtained by the known process.
  • the particles are relatively uniform in size.
  • the D50 may be from 100 to 250 pm, and the particles may have a SPAN ((D90-D10)/D50)) of less than 1. (D10, D50 and D90 may be measured by known methods, such as ASTM D1921-18.)
  • the particles can differ in composition of those obtained from the known process.
  • the polymer to be recycled comprises plasticisers and/or other soluble liquid additives.
  • flexible PVC generally comprises significant quantities of plasticisers.
  • Rigid PVC generally does not comprise plasticisers but may comprise other soluble liquid additives, such as stabilisers, phosphite ester or soybean oil.
  • any insoluble components present in the initial polymer material to be recycled are generally separated before the solution of step (a) is provided.
  • Plasticisers and/or other soluble liquid additives may nevertheless be present as dissolved species in the solution of step (a).
  • removal of at least some of the PSA from the solution in step (b) causes precipitation of the polymer to provide a slurry of polymer particles, water and the PAOS. It has been found that in this step a portion of the plasticisers and other soluble liquid additives stay dissolved in the slurry liquid phase. Thus, a portion of the plasticisers and other soluble liquid additives initially present are found in the liquid phase product or products separated in the solid-liquid separation of step (c) of the present invention.
  • the present invention also effectively and efficiently separates the polymer particles from at least a portion of plasticisers and/or other soluble liquid additives which are present.
  • the initial polymer comprises plasticisers and/or other soluble liquid additives
  • residual quantities of the plasticisers and/or other soluble liquid additives may be found in the residual PAOS and water of the separated polymer particles.
  • the polymer particles comprising residual PAOS and water which are separated in step (c), before any subsequent treatment if performed comprise less than 60% weight, such as less than 50% by weight or less than 40% by weight, of any plasticisers and/or soluble liquid additives which were present in the solution of step (a).
  • plasticisers and/or other soluble liquid additives in the separated polymer particles are generally much lower than those initially present in the polymer being recycled, and may be acceptable. In cases where complete or further removal of plasticisers and/or other soluble liquid additives is desired then the polymer particles may be subjected to a washing step or steps as already noted to remove further plasticisers and/or soluble liquid additives.
  • the present invention is preferably applied to a PVC polymer.
  • the following paragraphs apply to such embodiments, and in particular to the preparation of the solution of step (a).
  • the PVC may comprise PVC recycled from any suitable source. It may, for example, comprise PVC which has been physically separated from household or industrial waste. Preferably the PVC is obtained by recycling of PVC previously used for a particular application.
  • PVC is commonly used for window frames and profiles, and the PVC may therefore be or be derived from waste PVC window profiles.
  • Another common use of PVC is in wire and cable applications.
  • the PVC may be waste wire and cable or derived from waste wire and cable, for example by separating the PVC from the metal wire.
  • Other sources of the PVC include membranes, tarpaulins, textiles and other coated fabrics, PVC flooring, vinyl wallpaper, flexible hoses and numerous automotive applications.
  • the PVC prior to the dissolution in the solvent mixture is in the form of lumps, strips, flakes or chips, for example obtained by grinding, shredding, cutting or chopping of larger forms of product.
  • An example would be, for example, cut window profiles or PVC cable.
  • the PVC in this mixture and typically the mixture as a whole, more usually has an average particle size in the range of several millimetres to tens of millimetres, for example 5 to 80mm, with particle sizes of 5 to 25mm most usual.
  • Non-PVC components which as defined herein refers to components which are other than those typically found in a PVC composition, may be present.
  • Non-PVC components may, for example, comprise polyolefins and polymers other than PVC or polyolefins. These may be present, for example, because the PVC was used in an application with another polymer or may be present as “contaminants” from the PVC collection and sorting process.
  • the PVC is relatively “pure” of components other than those typically found in a PVC composition i.e. other than PVC resin and PVC additives which were originally added to the PVC resin for its intended use.
  • the PVC polymer prior to dissolution may have been, and preferably has been, obtained after treatment of an initial mixture comprising the PVC and other components, for example a mixed polymer stream or a stream comprising PVC and metals, such as copper, obtained from wire and cable scrap, to remove such components or any other foreign contaminant.
  • the dissolution of the PVC in the solvent mixture may be performed at any suitable temperature and pressure.
  • an elevated temperature such as a temperature in the range 90 to 120°C is preferred. Whilst ambient pressure can be used, elevated pressure is generally used at temperatures above the boiling point of the solvent mixture.
  • stirring is applied to assist in the dissolution step.
  • This Comparative Example describes the recycling of a cushion vinyl flooring waste according to methods known in the prior art.
  • the flooring waste is composed of 42.1% of PVC polymer resin, 21.8% of liquid additives, including phthalate plasticizers, and 36.1% of solid additives or insoluble components, including mineral fillers, metal stabilizers and glass fibers.
  • 600g of the flooring waste is dissolved in 2.5 kg of solvent composed of 76.2% of methyl ethyl ketone (MEK) as PAOS, 4.4% of water, 15.3% of iso-hexane, as PSA, and 4.1% of iso-propanol.
  • MEK methyl ethyl ketone
  • the dissolution is carried out at 100°C and 3 barg during 30 minutes under agitation.
  • the PVC solution obtained is mixed with a chelating agent in order to improve extraction of insoluble components, and the insoluble components then separated from the PVC solution by combining filtration using a Nutsche filter and centrifugation at 2000 G and 55°C during 225 seconds.
  • the obtained clarified PVC solution comprising the dissolved PVC polymer resin and also dissolved plasticizer components of the original flooring waste, is then transferred to a precipitation vessel along with a partially hydrolyzed polyvinyl alcohol (72% hydrolyzed) as dispersing agent.
  • PVC grains are precipitated together with the plasticizers initially in the flooring application.
  • the PVC grains are separated from the water and dried.
  • the total content of plasticizers in the PVC grains is 34,2% in weight i.e. corresponding to all the plasticisers original present.
  • This solution is then transferred to a precipitation vessel along with a partially hydrolyzed polyvinyl alcohol (72% hydrolyzed) as dispersing agent and 1.2 kg of an aqueous phase, composed of water saturated with MEK is added.
  • the initial temperature is 40-45°C.
  • the operating pressure is reduced to 600 mbar(a), inducing a first partial removal of the iso-hexane by flash.
  • Sufficient team is then injected to heat the mixture to 55°C.
  • the residual content of iso-hexane in the organic phase is around 2%, corresponding to a removal of approximately 99% of the initial iso-hexane solvent by flash and steam stripping.
  • the required steam consumption to reach this temperature is around 280 g, corresponding to 1.1 kg of steam per kg of the PVC polymer resin.
  • the aqueous phase comprises predominantly water saturated with MEK, but also some iso-propanol.
  • the organic phase comprises predominantly MEK, but also comprises iso-hexane, iso-propanol and water.
  • the organic phase also contains a portion of the plasticizers initially present in the flooring waste, solubilized in the organic phase.
  • the suspension is centrifuged at 2000 G during 225 seconds, resulting in three distinct phases - an aqueous phase, an organic phase and an intermediate phase comprising the PVC polymer grains, swollen by residual presence of solvent.
  • the organic phase and a part of the aqueous phase are separated by decantation and the intermediate phase mixed with the remaining aqueous phase to obtain PVC polymer grains in a slurry in the aqueous phase.
  • the slurry is agitated and pressure is reduced at 600 mbar(a). Steam is injected to evaporate residual MEK and any other remaining organic components of the solvent.
  • the required steam consumption will depend on the amount of aqueous phase in the vessel, but about 850g steam is required in this Example, leading to an overall steam consumption of 1.13 kg of steam, corresponding to approximately 4.5 kg of steam per kg of the PVC polymer resin. This is a reduction of total steam consumption compared to the Comparative Example.
  • the PVC polymer grains are separated from the water and dried in an oven at 80°C during 6 hours.
  • the total content of plasticizers in the PVC polymer grains obtained is 18.47% in weight showing that 46% of the plasticizers initially in the flooring waste are separated from the PVC in this Example.
  • the final PVC polymer grains have a D10 of l31 pm, D50 of 173 pm and D90 of 237 pm.
  • Example 1 is repeated except that the PVC polymer grains obtained after centrifugation and decantation of the organic phase and part of the aqueous phase are, prior to steam stripping, contacted with an organic solvent to remove further plasticisers. More specifically the organic solvent is composed of 83% MEK, 10.7% water, 4.3% isopropanol and 2% iso-hexane, and is obtained from the organic phase separated by the decantation after treatment to remove plasticisers. Contacting is performed 3 times for 10 minutes each time and at 55°C, with the weight ratio solvent/PVC for each of the 3 steps around 7.
  • the obtained PVC polymer grains are mixed with a portion of the aqueous phase to form a slurry which is then reduced in pressure and steam is injected to evaporate residual MEK and any other remaining organic components of the solvent as in Example 1.
  • the residual content of plasticizers in the PVC polymer grains is reduced to below 1% in weight.
  • Example 3 is largely the same as Example 2 except as indicated herein.
  • the initial feedstock used is a cable waste, composed of 28.4% of PVC polymer resin, 18.6% of liquid additives, including phthalate plasticizers and among others DEHP, and 53% of insoluble components, including rubber, polyolefins, mineral fillers such as CaCO3 and metal stabilizers such as Pb.
  • 750g of the cable waste is dissolved in 2.5 kg of solvent composed of 76.2% of MEK, 4.4% of water, 15.3% of iso-hexane and 4.1% of iso-propanol at 100°C and 3 barg during 30 minutes under agitation.
  • the PVC containing solution obtained is mixed with a chelating agent in order extract heavy metals and insoluble components, which are separated from the solution by combining filtration using a Nutsche filter and centrifugation as previously.
  • Partially hydrolyzed polyvinyl alcohol and 1.2 kg of aqueous phase are added and the pressure reduced and steam injected until the temperature reaches 55°C.
  • the required steam consumption to reach this temperature is around 220 g.
  • the required steam consumption to reach this temperature is around 300 g, corresponding to 1.0 kg of steam per kg of the PVC polymer resin.
  • the PVC polymer grains obtained after decantation are contacted 3 times at 55°C with an organic solvent as before except that the solvent/PVC ratio is 5.
  • the obtained PVC polymer grains are mixed with a portion of the aqueous phase to form a slurry which is then reduced in pressure and steam is injected to evaporate residual MEK and any other remaining organic components of the solvent as in Examples 1 and 2. 860g steam is required in this step, corresponding to approximately 4.0 kg of steam per kg of the PVC polymer resin.
  • the total residual content of plasticizers in the PVC grains obtained was 2.85% by weight. (Further reduction could be obtained by increasing the number of contacting steps or increasing the solvent-to-PVC ratio if required.)

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

La présente invention concerne un procédé de recyclage de polymères, et en particulier de polymères de polychlorure de vinyle (PVC), le procédé consistant à : a) prendre une solution contenant un polymère dissous dans un mélange de solvants contenant de l'eau, un solvant organique polaire aprotique (PAOS) et un agent de séparation de phase (PSA) organique; b) éliminer au moins une partie du PSA de la solution pour provoquer la précipitation du polymère et pour introduire une suspension de particules de polymère dans une phase liquide contenant de l'eau et le PAOS, c) effectuer une séparation solide-liquide sur la suspension pour séparer la majorité des PAOS et de l'eau présents dans la suspension, afin de produire des particules de polymère contenant du PAOS résiduel et de l'eau, et d) traiter les particules de polymère contenant du PAOS résiduel et de l'eau pour éliminer le PAOS résiduel et l'eau puis récupérer les particules de polymère.
PCT/EP2025/056196 2024-03-08 2025-03-06 Procédé Pending WO2025186410A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030119925A1 (en) * 2000-03-23 2003-06-26 Bernard Vandenhende Method for recycling a plastic material
WO2009037316A1 (fr) 2007-09-21 2009-03-26 Solvay (Societe Anonyme) Processus pour extraire un polymère à partir d'une solution

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030119925A1 (en) * 2000-03-23 2003-06-26 Bernard Vandenhende Method for recycling a plastic material
US7056956B2 (en) 2000-03-23 2006-06-06 Solvay (Societe Anonyme) Method for recycling a plastic material
WO2009037316A1 (fr) 2007-09-21 2009-03-26 Solvay (Societe Anonyme) Processus pour extraire un polymère à partir d'une solution
US20100305223A1 (en) * 2007-09-21 2010-12-02 Solvay (Societe Anonyme) Process for recovering a polymer from a solution

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