Method for recycling PVC plastic-based waste by liquid-liquid extraction

Abstract

The present invention relates to a method for recovering a stream of one or more purified PVC polymers from a PVC-based plastic feedstock comprising one or more PVC polymers and at least two families of additives, the method using a biphasic solvent system comprising two immiscible liquid phases A and B, the method comprising: a) a dissolving step that comprises bringing the plastic feedstock into contact with a dissolving liquid consisting of phase A to obtain at least one crude polymer solution (1); b) a step of liquid-liquid extraction, in at least one zone, of the crude polymer solution (1), the liquid-liquid extraction step being carried out in the presence of a single extraction liquid (4) consisting of phase B to obtain a purified polymer solution (3) and at least one final additive stream (2) comprising the at least two families of additives; c) a polymer-solvent separation step to separate the purified polymer solution into a stream of one or more purified PVC polymers and at least one solvent fraction comprising phase A.

Description

[0001] PVC PLASTICS-BASED WASTE RECYCLING PROCESS BY LIQUID-LIQUID EXTRACTION

[0002] technical field

[0003] The invention relates to the field of recycling poly(vinyl chloride) (PVC)-based plastics, in particular a process for treating a PVC-based plastic filler, typically derived from PVC-based plastic waste, to obtain a stream of at least one purified PVC polymer enabling its reuse in the manufacture of new plastic objects. More specifically, the invention relates to a process for treating a PVC-based plastic filler, particularly derived from PVC-based plastic waste, employing a two-phase solvent system, and based on the liquid-liquid extraction of a polymer solution previously obtained by dissolving PVC polymer(s) and additives from the PVC-based plastic filler in a dissolving liquid, and the separation of at least one PVC polymer and at least one solvent following the liquid-liquid extraction in order to recover a stream of at least one purified PVC polymer for further processing.

[0004] Previous technique

[0005] By definition, a plastic is a mixture consisting of a base polymer and numerous additives, the whole being capable of being molded or shaped (generally under heat and / or pressure) to produce a semi-finished product or a finished object. A common practice is to refer to the plastic by the name of its constituent polymer. Thus, polyvinyl chloride (PVC) plastic, as it is known in English, actually corresponds to the combination of the PVC polymer, sometimes referred to later as "PVC resin," with various additives chosen according to the required functionalities of the plastic. These additives can be organic (macro)molecules or inorganic (nano)particles and are used depending on the desired properties of the PVC plastic: resistance to heat, light, or mechanical stress; flexibility; ease of processing; color; etc.

[0006] Several methods exist for recycling PVC plastics: so-called conventional methods by simple mechanical recycling of plastics, methods involving modifications of their composition (possibly with chemical transformations of the initial constituents), etc.

[0007] Since the mid-20th century èmeIn the 20th century, the recycling of PVC plastic, involving a physical process, was the subject of numerous studies aimed, in a first step, at solubilizing the PVC resin with a variable proportion of additives and then, in a second step, at recovering the resin using various processes (precipitation, evaporation, etc.) in the presence of all or part of the soluble additives. For example, patents EP0945481 and EP1268628 on the one hand, and EP2276801 on the other, disclose processes for recycling various PVC-based objects (flexible or rigid pipes, window frames, cables, etc.) and specifically fiber-reinforced PVC objects (tarpaulins, floor coverings, etc.) using a process that involves a step of dissolving the PVC resin and soluble additives in an organic solvent, followed by a steam precipitation step allowing the recovery of the PVC resin and the majority of the additives.

[0008] However, retaining these additives in the recovered PVC for recycling is not always desirable. For example, changes in regulations over time impact recycling. For instance, certain plasticizing additives belonging to the phthalate family, widely used in the formulation of so-called "flexible" PVC some forty years ago, have been progressively subjected to authorization in Europe under the REACH regulation. Since the end of 2006, this regulation has aimed to ensure the safe manufacture and use of chemical substances in European industry, and has ultimately been progressively excluded from the list of usable additives (Annexes XIV and XVII of Regulation (EC) No 1907 / 2006 of the European Parliament and of the Council of 18 December 2006).Following the same trend, the use of cadmium-based metallic stabilizers in PVC plastic formulations, particularly those known as PVC compounds (especially so-called "rigid" PVC plastics), was prohibited by an amendment to Annex XVII (Regulation 494 / 2011 of 20 May 2011). Similarly, lead-based stabilizing additives were subject to restrictions (Annex XV) which were detailed and adopted between December 2017 and March 2018 by the ECHA's Risk Assessment Committee (RAC) and Socio-Economic Analysis Committee (SEAC). Thus, over the past 20 years, several families of additives have seen their range of use restricted, a phenomenon that is likely to intensify in the coming years.

[0009] These new regulations have led to a ban on the presence of numerous additives in recycled raw materials (RRMs), notably through the implementation of very stringent limits on permitted quantities (for example, the quantity of phthalates subject to authorization and considered in mixtures must not exceed 1000 ppm of the final composition of the RRM in question). Given the often very long lifespan of PVC-based products (several decades), PVC-based products formulated before the end of 2006 and now at the end of their life cannot be recycled using regeneration methods that would retain these prohibited additives, whether these methods are conventional, such as mechanical recycling processes, or non-conventional, such as the dissolution / precipitation processes mentioned above.

[0010] Given, on the one hand, current and future regulatory constraints and, on the other hand, the limitation of fossil resources which highlights the need to move towards a so-called "circular" economy, producing a purified polymer (i.e., as free as possible from additives) from plastic waste for reuse as a recycled polymer equivalent to a virgin petroleum-based polymer is today a major challenge for meeting the environmental challenges of the 21st century ème century.

[0011] Numerous processes have been considered to enable the extraction of various families of plastic additives, particularly PVC plastic. For example, and not exhaustively, patents EP1311599 and W02006053907 both propose a first step of dissolving the PVC resin and at least one family of additives with a first organic solvent, followed by one or more separation steps, notably via the addition of a second solvent or selective adsorbents in solid form to obtain, in particular, in the case of patent EP1311599, a PVC free of phthalate-type plasticizers and, in the case of patent W02006053907, a PVC free of heavy metals.Patent JP2007092035 discloses another example of possible implementation with a dissolution of the PVC resin and at least the phthalate-type additives via the use of a mixture of solvents under supercritical conditions and the recovery of said phthalates in this same mixture of solvents after "breaking" said supercritical conditions, then a step of extraction of the lead-based additives from the residual solid phase containing the PVC resin via the use of at least one liquid surfactant.

[0012] Despite these advances, removing all additives from PVC plastic, and even more so from a mixture of PVC-based plastics from various formulations, such as those found in post-consumer waste, remains a significant scientific and industrial challenge. The previously mentioned dissolution step is primarily useful for removing some of the additives that are insoluble in the chosen solvent(s). However, additives that are soluble in the solvent(s) are particularly difficult to separate, mainly due to their highly varied chemical nature.

[0013] One initial approach involves extracting these molecules by exploiting the difference in size (or more precisely, hydrodynamic volume) between polymer macromolecules and impurity molecules such as additives, using analytical methods called size exclusion chromatography (SEC) or equivalent derived methods employing fixed beds of size exclusion solids. These methods have the major advantage of separating the polymer fraction from other molecular compounds, usually in a single step, but they do not allow for the simultaneous separation of these molecular compounds from each other. An example of a PVC-based plastic waste recycling process using size exclusion polymer chain extraction (SEC-SMB) is described in patent application FR3142760.

[0014] A second approach relies on varying the physicochemical properties of all constituents, such as their polarity, solubility, boiling point, density, etc., to induce fractionation between polymer chains and at least one family of additives. As explained above, this usually results in multiple purification steps, given the number and diversity of additives present, which often need to be considered individually. For example, patent application JP2007191586 implements, after preliminary dissolution and filtration steps as previously mentioned, successive separation steps by liquid-liquid (L / L) extraction using, at each step, an additional solvent specific to the extraction of a particular family of additives.Thus, starting from a solution based on the solvent tetrahydrofuran (THF), the addition of dimethyl sulfoxide (DMSO) followed by a first L / L extraction allows the removal of phthalate-type plasticizers, while the addition of an acidic aqueous solution followed by a second L / L extraction step allows the removal of lead-based metallic stabilizers (and derivatives).

[0015] Therefore, obtaining a stream of at least one purified PVC polymer typically involves developing processes that employ a large number of unit operations with a solvent specific to each operation for separating the additives, family by family, from the polymer. Besides the difficulty of such implementation, particularly given the quantity of additives present in the waste to be treated, it often proves very costly. It is thus complicated to find an economically viable balance between the resale cost, equivalent to the added value, of the products obtained and the cost of the unit operations involved in the regeneration process, which is all the more true if the extracted additives are not recovered.

[0016] Finally, processing a plastic load from PVC-based plastic waste involves proposing a robust and versatile process to take into account the variability of the additives present depending on the origin of the waste considered (by origin we include in particular the intended use of the PVC-based object and its production date).

[0017] Objectives and Summary of the Invention

[0018] The present invention thus proposes an alternative approach to address the problems described above, with a process that, in a single purification step using a liquid-liquid extraction method with a single extraction liquid, separates the PVC polymer fraction(s) from at least two families of additives, and advantageously allows for the separation of various families of additives from each other. The present invention is based in particular on the use of an innovative solvent system comprising two immiscible liquid phases, A and B, exhibiting specific affinities, in terms of physicochemical properties, with both the PVC polymer chains and the additives considered. Phase B constitutes the single extraction liquid used for the liquid-liquid extraction in the process according to the invention.

[0019] The present invention therefore makes it possible, from a polymer solution containing at least one PVC polymer solubilized in a dissolution medium consisting of phase A of the biphasic solvent system, and containing the associated soluble additives, to selectively extract said PVC polymer and at least two families of associated additives, regardless of the nature of said additives.

[0020] The application of liquid / liquid extraction technology using a single extraction liquid as a method for purifying PVC-based plastic waste to obtain a purified PVC polymer stream and at least one final additive stream comprising at least two families of additives, allowing respectively their reuse as MPR for the manufacture of new plastic objects and their subsequent recovery, has never been proposed.

[0021] The present invention aims to overcome the problems of the prior art and contribute to the recycling of PVC plastics. Furthermore, it offers the potential for significant gains in energy efficiency and the final recovery of products, i.e., PVC polymer(s) and additives, and thus represents a major step forward in the development of economically and environmentally viable processes.

[0022] Thus, to achieve at least one of the aforementioned objectives, among others, the present invention proposes, according to a first aspect, a process for recovering a purified PVC polymer stream from a PVC-based plastic feed comprising one or more PVC polymers and at least two families of additives, employing a two-phase solvent system comprising two immiscible liquid phases A and B, said process comprising: a) a dissolution step comprising contacting the PVC-based plastic feed with a dissolution liquid consisting of phase A, to obtain at least one crude polymer solution; b) a liquid-liquid extraction step, in at least one zone, of the crude polymer solution, in the presence of a single extraction liquid consisting of phase B, to obtain a purified polymer solution and at least one final additive stream comprising said at least two families of additives;c) a polymer-solvent separation step, to separate the purified polymer solution into a stream of purified PVC polymer(s) and at least a solvent fraction comprising phase A.;

[0023] According to one or more embodiments, step b) is carried out in a single area to form the purified polymer solution and a single final additive stream comprising said at least two families of additives.

[0024] According to one or more embodiments, step b) is carried out in at least two zones to form the purified polymer solution and a single final additive stream comprising said at least two families of additives or at least two final additive streams each containing one of said two families of additives.

[0025] According to one or more embodiments, step b) of liquid-liquid extraction is carried out in two zones and comprises: bl) a substep of liquid-liquid extraction of the crude polymer solution in the presence of the extraction liquid in a first extraction zone to obtain an intermediate polymer(s) solution and a first final additive stream comprising a first family of additives; b.2) a liquid-liquid extraction substep of said intermediate polymer solution in the presence of the extraction liquid in a second extraction zone fluidically coupled to said first extraction zone, to obtain the purified polymer solution and a second final additive stream comprising a second family of additives; preferably the mass ratio of the extraction liquid to the intermediate polymer solution in the second extraction zone is greater than or equal to the mass ratio of the extraction liquid to the crude polymer solution in the first extraction zone.

[0026] According to one or more embodiments, step b) of liquid-liquid extraction is carried out in two zones and comprises: b.3) a liquid-liquid extraction substep in an extraction zone of a feed formed by a mixture of the crude polymer solution with a first phase A stream, in contact with the extraction liquid, to obtain the purified polymer solution and an intermediate extract comprising said at least two families of additives; b.4) a liquid-liquid extraction substep of said intermediate extract in a counter-extraction zone to counter-extract the PVC polymer(s) of said intermediate extract in contact with an initial phase A stream and obtain the final additive stream comprising said at least two families of additives and said first phase A stream mixed with the crude polymer solution to form the feed sent to step b.3), preferably the mass ratio of extraction liquid / sum of crude polymer solution and first phase A flow in the extraction zone being less than the mass ratio of intermediate extract to initial phase A flow in the counter-extraction zone.

[0027] According to one or more embodiments, step b) of liquid-liquid extraction is carried out in two zones and comprises: b.5) a liquid-liquid extraction substep in an extraction zone of a feed formed by a mixture of the crude polymer solution with a first fraction of a first phase A stream, in contact with the extraction liquid, to obtain the purified polymer solution and an intermediate extract comprising said at least two families of additives; b.6) a liquid-liquid extraction substep of said intermediate extract in a counter-extraction zone to counter-extract the PVC polymer(s) of said intermediate extract in contact with an initial phase A stream and obtain a first final additive stream comprising a first family of additives and said first phase A stream, and the first fraction of the first phase A stream and a second complementary fraction (of the first phase A stream) constituting a second final additive stream comprising a second family of additives. According to one or more embodiments, liquid-liquid extraction step b) is carried out in at least three zones and comprises: b.7) a liquid-liquid extraction substep in a first zone of a feed formed by a mixture of the crude polymer solution with a first fraction of a first phase A stream, in contact with extraction liquid, to obtain the purified polymer solution and a first intermediate stream comprising said at least two families of additives; b.8) a liquid-liquid extraction substep of said first intermediate stream in contact with an initial phase A stream in a second zone to counter-extract the PVC polymer(s) of said first intermediate stream and separate the two families of additives between phases A and B, and obtain a final first additive stream comprising a first family of additives and a second phase A stream comprising a second family of additives; b.9) a liquid-liquid extraction substep of the second phase A stream in a third zone in contact with extraction liquid, to form said first phase A stream and a second intermediate stream sent to the second zone in step b.8); and a withdrawal of the first phase A stream exiting the third zone is carried out to form the first fraction of the first phase A stream and a second complementary fraction (of the first phase A stream) constituting a final second additive stream comprising a second family of additives.

[0028] According to one or more embodiments, phase B has a lower density than phase A and flows upwards and counter-currently to phase A in said at least one zone in step b).

[0029] According to one or more embodiments, said at least one zone in step b) of liquid-liquid extraction comprises at least one piece of liquid-liquid extraction equipment selected from:

[0030] - gravity columns equipped with perforated trays;

[0031] - gravity columns equipped with bulk or structured packing;

[0032] - gravity columns equipped with trays and bulk or structured packing;

[0033] - agitated columns;

[0034] - pulsed columns;

[0035] - cascade mixer-decanters;

[0036] - centrifugal partition chromatography devices; and

[0037] - centrifugal extractors.

[0038] According to one or more embodiments, the process includes a step a') of separating the insolubles from the crude polymer solution obtained at the end of step a) before sending it to step b).

[0039] According to one or more embodiments, the solvent system is characterized in that:

[0040] - phase A and phase B each comprise an organic solvent or a mixture of organic solvents chosen from the same list consisting of ketones, amides, azines, esters, ethers, halogenated solvents, hydrocarbons, sulfide solvents, and dihydrolevoglucosenone;

[0041] - the organic solvent or mixture of organic solvents of said phase A is capable of solubilizing the PVC polymer(s) of the PVC-based plastic filler;

[0042] - the two-phase solvent system is capable of solubilizing at least two families of additives;

[0043] - The partition coefficient of the PVC polymer(s) in the two-phase solvent system, defined as the ratio of the mass concentrations of the PVC polymer(s) dissolved in phase B and in phase A, tends towards zero, and the partition coefficient of said families of additives in the two-phase solvent system, defined as the ratio of the mass concentrations of said families of additives dissolved in phase B and in phase A, is greater than or equal to 0.05. According to one or more embodiments, the organic solvent(s) for each of phases A and B of said two-phase solvent system are chosen from the list consisting of:

[0044] - the following compounds from the ketone family: methyl ethyl ketone, diethyl ketone (DEK), 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone, cyclopentanone and cyclohexanone;

[0045] - the following compounds from the amide family: N,N-diethylformamide, 2-pyrrolidone and

[0046] - the following compounds from the azine family: pyridine, 4-aminopyridine, 2-aminopyridine, and 4-vinylpyridine;

[0047] - the following compounds from the ester family: methyl acetate, ethyl acetate, methyl propionate, n-butyl propionate, γ-butyrolcatone and γ-valerolactone;

[0048] - the following compounds from the ether family: methoxycyclopentane, diisopropyl ether, tetrahydrofuran and methyl tetrahydrofuran;

[0049] - the following compounds from the family of chlorinated solvents: dichloromethane and trichloromethane;

[0050] - the following compounds from the hydrocarbon family: xylene, cyclohexane, toluene, isohexane and n-heptane;

[0051] - the following compound from the family of sulfide solvents: dimethyl sulfoxide (DMSO);

[0052] - dihydrolevoglucosenone.

[0053] According to one or more embodiments, phase A of said two-phase solvent system comprises a first mixture of at least two of the following organic solvents:

[0054] - a predominantly sulfurous solvent,

[0055] - a first minor solvent selected from ketones and cyclic esters, preferably selected from methyl ethyl ketone, DEK, 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone, cyclopentanone, γ-butyrolcatone, and γ-valerolactone, and phase B comprises a second mixture of at least two of the following organic solvents:

[0056] - a major solvent chosen from hydrocarbons, preferably from xylene, isohexane and n-heptane,

[0057] - a first minor solvent chosen from among the ketones and cyclic esters, preferably chosen from among methylethyl ketone, DEK, 4-heptanone, 2,4-dimethyl-3-pentanone, methylisobutyl ketone, cyclopentanone, y-butyrolcatone, and y-valerolactone.

[0058] According to one or more embodiments, the first mixture of phase A of said two-phase solvent system comprises at least three of the following organic solvents:

[0059] - the major solvent DMSO, at a content of at least 50% by weight, - the first minor solvent chosen from among ketones and cyclic esters, preferably from among diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, γ-butyrolcatone and γ-valerolactone, and

[0060] - a second minor solvent selected from hydrocarbons, preferably from xylene, cyclohexane, isohexane and n-heptane, and the second mixture of phase B of said two-phase solvent system comprises the following three organic solvents:

[0061] - the major solvent, with a content of at least 50% by weight, chosen from hydrocarbons, preferably from xylene, cyclohexane, isohexane and n-heptane,

[0062] - the first minor solvent chosen from among ketones and cyclic esters, preferably from diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, γ-butyrolcatone, and γ-valerolactone, and

[0063] - a second minor solvent chosen from among the sulfide solvents, preferably DMSO.

[0064] According to one or more embodiments, the first mixture of phase A of said two-phase solvent system comprises the following three organic solvents:

[0065] - the major solvent DMSO, at a content of at least 50% by weight, preferably at a content between 50% and 70% by weight, preferably between 55% and 65% by weight;

[0066] - the first minor solvent DEK, preferably at a content between 20% and 40% by weight, preferably between 25% and 35% by weight, and

[0067] - the second minor solvent n-heptane, preferably in a content less than or equal to 15% by weight, preferably between 5% and 15% by weight, preferably between 5% and 10% by weight, and the second mixture of phase B of said biphasic solvent system comprises the following three organic solvents:

[0068] - the major solvent n-heptane, at a content of at least 50% by weight, and preferably at a content between 50% and 70% by weight of n-heptane, preferably between 55% and 65% by weight;

[0069] - the first minor solvent DEK, preferably at a content between 20% and 40% by weight, preferably between 25% and 35% by weight, and

[0070] - the second minor solvent DMSO, preferably at a content less than or equal to 15% by weight, preferably between 5% and 15% by weight, preferably between 5% and 10% by weight.

[0071] According to one or more embodiments, the aforementioned at least two families of PVC-based plastic filler additives are included in the list consisting of:

[0072] - the family of organotins used as stabilizing additives;

[0073] - metallic compounds used as stabilizing additives containing lead or cadmium, preferably lead and cadmium stearates; - the family of ortho-phthalates used as plasticizing additives, preferably dioctyl phthalate DOP, bis(2-ethylhexyl) phthalate DEHP, dibutyl phthalate DBP, benzyl butyl phthalate BBP, di-isobutyl phthalate DIBP, di-pentyl phthalate DPP;

[0074] - the family of terephthalates used as plasticizing additives;

[0075] - the family of trimellitates used as plasticizing additives;

[0076] - the family of benzoates used as plasticizers;

[0077] - the family of mono, di and triphosphites and their derivatives used as heat stabilizing additives;

[0078] - the family of phenyl 1,3-diones used as heat-stabilizing additives;

[0079] - the family of organophosphates used as flame retardant additives.

[0080] According to one or more embodiments, the partition coefficient of the additives of said at least two families of additives of the PVC-based plastic filler in the two-phase solvent system is between 0.05 and 5, preferably between 0.5 and 5.

[0081] According to one or more embodiments, the two-phase solvent system does not induce precipitation of the PVC polymer(s).

[0082] According to one or more embodiments, the partition coefficient of the PVC polymer(s) in the two-phase solvent system is less than or equal to 0.01, preferably between 0 and 0.01.

[0083] Other objects and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of non-limiting examples, the description being made with reference to the attached figures described below.

[0084] List of figures

[0085] Figure 1 is a schematic diagram of the liquid-liquid extraction step of the process for recovering a purified PVC polymer(s) stream according to the invention.

[0086] Figure 2 is a diagram illustrating the liquid-liquid extraction step in a single zone according to a first implementation of the invention.

[0087] Figure 3 is a diagram illustrating the liquid-liquid extraction step in two coupled extraction zones according to a second embodiment of the invention.

[0088] Figure 4 is a diagram illustrating the liquid-liquid extraction step in two coupled zones formed by an extraction zone and a counter-extraction zone according to a third embodiment of the invention.

[0089] Figure 5 is a diagram illustrating the liquid-liquid extraction step in two coupled zones formed by an extraction zone and a counter-extraction zone, with intermediate withdrawal of a phase A flow, according to a fourth embodiment of the invention. Figure 6 is a diagram illustrating the liquid-liquid extraction step in three coupled zones formed by two extraction zones and a counter-extraction zone, according to a fifth embodiment of the invention.

[0090] Figure 7 is a diagram illustrating the liquid-liquid extraction step in four coupled zones formed by two extraction zones and two counter-extraction zones according to a sixth embodiment of the invention.

[0091] In the figures, the same references designate identical or analogous elements.

[0092] Description of the implementation methods

[0093] The invention proposes a process for recovering a purified PVC polymer stream from a PVC-based plastic feed comprising one or more PVC polymers and at least two families of additives, employing a biphasic solvent system comprising two immiscible liquid phases A and B, said process comprising: a) a dissolution step comprising contacting the PVC-based plastic feed with a dissolution liquid consisting of the liquid phase A of the biphasic solvent system (also referred to herein as phase A), to obtain at least one crude polymer solution, advantageously comprising the PVC polymer(s) and said at least two families of additives in solute form;then a') an optional step of separating the insolubles from the crude polymer solution obtained at the end of step a) before sending said crude polymer solution, which may also be called clarified polymer solution, to a liquid-liquid extraction step b), said step a') also advantageously providing an insoluble fraction; then b) a liquid-liquid extraction step, in at least one zone, of the crude polymer solution (or optionally of the clarified polymer solution), in the presence of a single extraction liquid consisting of the liquid phase B of the two-phase solvent system (also referred to herein as phase B) to obtain a purified polymer solution and at least one final additive stream comprising said at least two families of additives; c) a polymer-solvent separation step, to separate the purified polymer solution into a stream of purified PVC polymer(s) and at least one solvent fraction comprising the liquid phase A;d) an optional step of separating the additives from the solvent(s) in the final additive stream(s) comprising at least two families of additives.;

[0094] Terminology

[0095] Some definitions and clarifications are given below, although more details on the objects defined below may be given later in the description.

[0096] A poly(vinyl chloride) (PVC) product is defined as a product, generally a consumer product, that includes, and preferably is made of, at least one PVC plastic. PVC plastic is defined as a combination of a PVC polymer, also called PVC resin, with various additives chosen according to the functionalities required for the PVC plastic, which are themselves chosen according to the intended applications.

[0097] PVC polymer is traditionally produced by the radical polymerization of vinyl chloride (VCM), a monomer itself obtained from chlorine and ethylene. The present invention enables the processing of any type of PVC plastic filler and the recycling of any grade of PVC polymer. The use of the plural with the term "PVC polymers" encompasses the various existing PVC resins, which are of the same chemical nature but of varying grades.

[0098] The additives used in the composition of PVC plastic can be organic molecules or macromolecules, as well as inorganic (nano)particles, and are used according to the properties they impart to the PVC resin. Generally speaking, and without being exhaustive, the formulation of PVC plastic involves at least one of the families of additives described below:

[0099] - Stabilizers to limit the degradation of polymer chains by dehydrochlorination and / or oxidation under the effect of heat, light, oxygen and / or mechanical stress. The nature of these stabilizers, for example metallic compounds (containing Pb, Sn, Ca, Zn, or Cd) or organic compounds, depends on the required properties and therefore the intended applications. Some examples of stabilizers frequently used in the past or currently are the following: lead stearate, dibasic lead stearate, dibasic lead phthalate, zinc stearate, calcium stearate, etc., taken alone or in mixtures, but also organotins (e.g., 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate of 2-ethylhexyl), mono, di and triphosphites and their derivatives (e.g., di(8-methylnonyl) and phenyl phosphite), or phenyl 1,3-diones such as dibenzoylmethane (DBM).Co-stabilizers can also be considered, for example epoxidized oils.

[0100] - Plasticizers are used to induce flexibility and improved impact and cold resistance in PVC plastic. The most widely used of these belong to the phthalate family. These are obtained by reacting phthalic anhydride with alcohols of varying carbon chains and consist of a benzene ring and two carboxylic ester groups positioned ortho to the benzene ring. Dioctyl or diethylhexyl phthalate (DOP or DEHP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP) are examples of phthalates that were widely used in the past or are still in use today.Other non-phthalic plasticizers are used today such as bis(2-ethylhexyl) adipate (DEHA) or diisononyl ester of cyclohexane-1,2-dicarboxylic acid (DINCH), terephthalates such as dibutyl terephthalate or dioctyl terephthalate (DEHT), trimellitates such as trioctyl benzene-1,2,4-tricarboxylate or benzoates; - lubricants to control intermolecular friction forces within the polymer itself (internal lubricants such as stearic acid, etc.) or between the polymer and the metal walls of the processing tools (external lubricants such as paraffins, polyethylene waxes, etc.).

[0101] - inert fillers, also called "fillers", mostly mineral (calcium carbonate (CaCOs), carbon black, kaolin, glass fibers, etc.), which act as diluents or to improve certain mechanical, electrical, thermal, etc. properties;

[0102] - dyes and / or pigments, such as titanium dioxide (TiOz) or carbon black, the latter being insoluble in the polymer and therefore present in the form of particles dispersed in the PVC plastic;

[0103] - shock-absorbing agents, generally polymers, such as polyacrylates and copolymers, such as methacrylate-butadiene-styrene (MBS), whose role is to reduce the fragility of PVC, particularly at low temperatures;

[0104] - flame retardant agents, such as organophosphate compounds (OPFRs or organophosphate flame retardants according to Anglo-Saxon terminology) like tris(2-ethylhexyl) phosphate, triphenyl phosphate (TPP), tri-o-cresyl phosphate or trixylenyl phosphate,

[0105] - other additives: antioxidants, anti-UV agents, biocides, antistatic agents, reinforcements, etc.

[0106] Impurities are defined as all elements other than PVC plastics (PVC polymer(s) with additives) as described above, included in the PVC-based plastic feedstock, particularly that derived from PVC-based plastic waste, which the process according to the invention aims to treat. These impurities can be "external" or "internal." External impurities are defined as impurities arising from the life cycle of PVC-based objects and / or from the collection and sorting process, or even from pretreatment operations of PVC-based plastic waste. These impurities may be metallic, organic, or mineral. They may consist of residues of materials (excluding PVC plastics) constituting the PVC-based objects or other objects that have been in contact with the PVC-based objects, soiling (food, biomass, soil / rubble, glue, etc.), etc.These impurities from use can thus, but are not limited to, include glass, wood, cardboard, paper, metal, rubber, silicones, plastics other than PVC (e.g., PET, etc.), mineral elements, etc. Any degradation products of PVC polymers and / or additives formed over time during the product's lifespan are also considered impurities and are classified as internal.

[0107] The terms "plastic filler," "PVC-based plastic filler," or "PVC filler" in the following text refer to any material containing one or more PVC plastics, potentially obtained at any stage of a PVC plastic's lifecycle, from its production to its mechanical or (physico-)chemical recycling, and which requires fractionation within the framework of establishing a circular economy specific to these PVC plastics. Depending on its origin, it may contain one or more PVC polymers, as well as additives derived from one or more PVC plastic formulations.

[0108] The term "solvent system" or "biphasic solvent system" refers to the two immiscible liquid phases, comprising at least two organic solvents, necessary for implementing a liquid-liquid extraction separation technique, and specifically adapted for the fractionation of a PVC-based plastic filler as defined above. The organic solvents forming the biphasic solvent system are immiscible or partially miscible. Regarding miscibility or partial miscibility: the organic solvents comprising the solvent system are immiscible or partially miscible in such a way as to form two distinct liquid phases separated by an interface (immiscible liquid phases A and B).

[0109] The term "partition coefficient" refers to the value quantifying the partitioning of a solute between the two immiscible liquid phases A and B of the solvent system, in particular the ratio of the mass concentrations of said solute in phase B (numerator), i.e., the extraction liquid, and in phase A (denominator), i.e., the liquid phase included in the crude polymer solution. This coefficient governs, for example, the elution order of compounds during a liquid-liquid extraction process. In this description, the term "polymer solution" refers to a liquid medium comprising a dissolution liquid, consisting of phase A of the two-phase solvent system used in the process according to the invention, and at least one dissolved PVC polymer, i.e., solvated and dispersed, in said dissolution liquid (i.e., phase A), the dissolved PVC polymer being initially present in the PVC-based plastic feedstock treated by the process according to the invention.If the polymer solution is referred to as "crude" in this description, it further comprises soluble plastic filler additives (solubilized in the dissolving liquid) and possibly impurities (soluble or insoluble) and / or insoluble additives (suspended in the polymer solution). Depending on the steps implemented in the process according to the invention, said crude polymer solution may therefore comprise additives, and possibly impurities, in the form of insoluble particles that are advantageously suspended in said polymer solution (in the case of insoluble additives / impurities of nanometric size, these will be referred to as colloidal solutions), and comprises additives, in particular at least two families of additives, and possibly impurities, that are soluble and dissolved in the dissolving liquid (i.e., phase A).

[0110] In this description, the terms "purified polymer solution" and "purified PVC polymer stream" represent the principal and valuable products obtained during the processing of a PVC-based plastic filler, particularly one derived from PVC-based plastic waste, by the process according to the invention. Said purified polymer solution and said purified PVC polymer stream comprise at least one PVC resin of a given grade, preferably a mixture of PVC resins of the same chemical nature but of varying grades. The term "purified" means in particular that the polymer solution obtained after liquid-liquid extraction and the PVC polymer stream obtained at the end of the process according to the invention comprise negligible or at least very low levels, in all cases compliant with applicable regulations, of additives as described above, and possibly of impurities also described above.The purified polymer stream also comprises a negligible or at least very low, preferably zero, content of at least one solvent, and preferably of all solvents, of the two-phase solvent system as used according to the process of the invention, and in this case, of the solvent(s) of phase A of the two-phase solvent system. Thus, more particularly, the purified PVC polymer stream has the following contents of additives and any impurities (contents expressed as weight percentages relative to the total weight of the final product, i.e., the mass of the PVC polymer(s) plus the mass of the additives and any other residual impurities):

[0111] - a content of less than 0.1% by weight, taken as a mixture, of phthalates subject to authorization by the REACH regulation in Europe (Annex XIV of Regulation (EC) No 1907 / 2006 of the European Parliament and of the Council of 18 December 2006), in particular less than 0.1% by weight of phthalates selected from the list consisting of the following phthalates: dibutyl phthalate (DBP), dioctyl or diethylhexyl phthalate (DOP or DEHP), benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate,

[0112] - a content of less than 0.1% by weight of the element lead, in particular said lead contained in additives of the metallic stabilizer type assessed under the REACH regulation and subject to restrictions (Annex XV) detailed and adopted between December 2017 and March 2018 by the ECHA's Risk Assessment Committee (RAC) and Socio-Economic Analysis Committee (SEAC),

[0113] - a content of less than 0.1% by weight, and preferably less than 0.01% by weight, of the element cadmium, in particular said cadmium contained in additives of the type metallic stabilizers prohibited by the REACH regulation according to the amendment of Annex XVII (Regulation 494 / 2011 of 20 May 2011),

[0114] - more generally a content of less than or equal to 2.0% by weight, preferably less than 1.0% by weight, even more preferably less than or equal to 0.5% by weight, or even less than or equal to 0.1% by weight or 0.01% by weight, of additives and any impurities.

[0115] In this description, the term "final additive stream" refers to a potentially usable by-product obtained after processing a PVC-based plastic filler, particularly one derived from PVC-based plastic waste, by the process according to the invention. It comprises additives from at least one family of additives, understood as compounds of similar chemical nature, molar mass, polarity, etc., initially present in the PVC-based plastic filler, solubilized in the two-phase solvent system, and separated in the liquid / liquid extraction step of the process according to the invention.The process according to the invention allows obtaining at least one final additive stream comprising at least two families of additives initially contained in the crude polymer solution, meaning that step b) of liquid-liquid extraction of the process according to the invention can produce a single final additive stream comprising said at least two families of additives, or two final additive streams each comprising one of said two families of additives and possibly other families of additives, or even more than two final additive streams of which at least two final additive streams each comprise one of said two families of additives.

[0116] The final additive stream(s) obtained during the process according to the invention may comprise a negligible or at least very low, preferably zero, content of PVC polymer(s). Thus, more particularly, a final additive stream may have a PVC polymer(s) content (expressed as a percentage by weight relative to the total weight of the purified additive stream obtained) of 5.0% or less by weight, preferably 1.0% or less by weight, preferably less than 0.5% by weight, and even more preferably less than or equal to 0.1% by weight.

[0117] In this description, the expression "greater than..." is understood as strictly greater than, and symbolized by the sign ">", and the expression "less than" as strictly less than, and symbolized by the sign "<". When the limit is included, the clarification will be provided by the respective expressions "greater than or equal to..." (corresponding to the sign ">") and "less than or equal to" (corresponding to the sign "<").

[0118] In this description, ambient temperature (Tamb) is typically understood to be 20°C ± 5°C, and atmospheric pressure is 0.101325 MPa.

[0119] According to the present invention, pressures are absolute pressures, and are given in MPa, unless otherwise indicated.

[0120] In this description, the term "include" is synonymous with (means the same as) "comprise," "include," and "contain," and is inclusive or open-ended, not excluding other elements not mentioned. It is understood that the term "include" includes the exclusive and closed term "consist."

[0121] In this description, the expression "between ... and ..." means that the limit values ​​of the interval are included in the range of values ​​described, unless otherwise specified.

[0122] In this description, the various parameter ranges characterizing a given system or stage, such as ranges relating to compound contents, dimensions (lengths, diameters, etc.), flow rates, mass ratios, number of theoretical stages, pressure ranges, or temperature ranges, may be used alone or in combination. For example, in this description, a preferred pressure range may be combined with a preferred temperature range, or a preferred compound content range for phase A of the solvent system may be combined with a preferred compound content range for phase B of the solvent system.

[0123] In the following, specific embodiments of the invention are described. They can be implemented separately or in combination with each other, without limitation as to the number of combinations where technically feasible.

[0124] In this description, a step refers to an operation or group of similar operations performed on a given flow at a specific point in the process. The process is described in its various steps, taken in the order in which the flows or products occur.

[0125] Finally, the terms "upstream" and "downstream" should be understood in relation to the overall flow of the fluid(s) or stream(s) in question within the process. More specifically, the terms "upstream" and "downstream" are defined in relation to the flow of the stream containing the PVC polymer(s). For example, the terms "upstream" and "downstream" are defined in the liquid / liquid extraction step with respect to the polymer solution stream, that is, either at the feed of said step b) with crude (or clarified) polymer solution or at the outlet point of the purified polymer solution obtained at the end of this step b) (i.e., the raffinate withdrawal point).

[0126] The description of the process according to the invention below refers to the diagrams in Figures 1 to 7, illustrating various, non-limiting, implementations of the process according to the invention.

[0127] PVC-based plastic filler

[0128] The process according to the invention is fed by a PVC-based plastic filler, and more particularly derived from PVC-based plastic waste. It may also be called "PVC filler" or "plastic filler" and comprises at least one PVC plastic, as defined in general terms above. Said plastic filler is advantageously a PVC filler to be recycled of the "production scraps" type, i.e., waste from the production processes of the PVC polymer during its polymerization or of the PVC plastic during its formulation / shaping, or of the PVC-based object during its production; or of the "installation scraps" type, i.e., waste generated during the installation or placement of said plastic-based object in its environment of use (for example, floor covering installation by tradespeople); or of the "post-consumer waste" type, i.e., waste generated after consumption by the user of said PVC-based object.In particular, the plastic load to be recycled can come from any existing collection and sorting channels or networks for production scraps and / or installation scraps and / or post-consumer waste allowing to isolate a stream based on at least one PVC plastic, including collection and sorting channels or networks specific to plastic waste.

[0129] Thus, the plastic material, which is typically of the "production offcuts" and / or "installation offcuts" and / or "post-consumer waste" type, generally originates from the major application areas that use PVC plastic, such as, but not limited to, the building and construction, packaging, automotive, electrical and electronic equipment, sports, and medical equipment sectors. Preferably, the PVC material comes from the building and construction sector. More specifically, PVC-based products are generally used in these sectors as profiles (windows, doors, blinds, roller shutter boxes), pipes and fittings, various rigid products and bottles, rigid sheets and films, flexible films and sheets, flexible tubes and profiles, cables, floor coverings, coated fabrics, etc.

[0130] Advantageously, the plastic filler comprises at least 50% by mass, preferably at least 70% by mass, preferably at least 90% by mass and even more preferably at least 95% by mass of PVC plastic.

[0131] The plastic filler can typically comprise between 30% and 99.9% by weight, preferably between 30% and 95% by weight and even more preferably between 35% and 80% by weight, of PVC polymer(s).

[0132] The plastic filler may typically comprise between 0.1% and 70% by weight, preferably between 5% and 70% by weight and, even more preferably, between 20% and 65% by weight of additives.

[0133] The additive(s) contained in the PVC-based plastic filler may be included in the following list:

[0134] - stabilizing or co-stabilizing additives, of the metallic (containing Pb, Sn, Ca, Zn, or Cd) or organic type, chosen for example from metallic stearates of zinc (e.g., zinc stearate), calcium (e.g., calcium stearate), lead (e.g., lead stearate, dibasic lead stearate) or cadmium (e.g., cadmium stearate), dibasic lead phthalate, epoxidized oils, organotins (e.g., 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate of 2-ethylhexyl), mono-, di- and triphosphites as well as their derivatives (e.g., di(8-methylnonyl) phenyl phosphite), phenyl 1,3-diones (e.g. dibenzoylmethane (DBM)), etc. ;

[0135] - plasticizing additives chosen, for example, from the phthalate family, such as dioctyl or bis(2-diethylhexyl) phthalate (DOP or DEHP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), diisobutyl phthalate (DIBP), di-n-octyl phthalate (DNOP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl phthalate, isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, or from other non-phthalic compounds such as bis(2-ethylhexyl) adipate (DEHA) or diisononyl ester of acid cyclohexane-l,2-dicarboxylic (DINCH), terephthalates such as dibutyl terephthalate or dioctyl terephthalate (DEHT), trimellitates such as trioctyl benzene-l,2,4-tricarboxylate or benzoates;

[0136] - Lubricating additives chosen for example from stearic acid, paraffins and polyethylene waxes; - Inert or coloring additives chosen for example from calcium carbonate (CaCOs), carbon black, kaolin, glass fibers, titanium dioxide (TiOz);

[0137] - anti-shock polymer or copolymer additives chosen for example from polyacrylates and methacrylate-butadiene-styrene;

[0138] - flame retardant additives chosen for example from organophosphates (OPFR) such as tris(2-ethylhexyl) phosphate, triphenyl phosphate (TPP), tri-o-cresyl phosphate or trixylenyl phosphate.

[0139] Preferably, the plastic filler includes additives that may be additives closely monitored by ECHA (ECHA, Investigation Report on PVC and PVC additives, version no. 1, 22 / 11 / 2023) and / or subject to REACH regulations, in particular chosen from the group consisting of:

[0140] - the organotin family, used as stabilizers, such as 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate of 2-ethylhexyl (DOTE), etc.;

[0141] - metallic compounds used as stabilizers such as those based on lead and cadmium subject to REACH restrictions, such as lead and cadmium stearates, etc.;

[0142] - the family of ortho-phthalates, used as plasticizers, some of which are subject to regulations, such as dioctyl phthalate (DOP), bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di-isobutyl phthalate (DIBP), dipentyl phthalate (DPP), etc.;

[0143] - the terephthalate family, used as plasticizers, such as dibutyl terephthalate, etc.;

[0144] - the trimellitate family, used as plasticizers, such as trioctyl benzene-1,2,4-tricarboxylate, etc.;

[0145] - the benzoate family, used as plasticizers;

[0146] - the family of mono, di and triphosphites and their derivatives, used as heat stabilizers, such as di(8-methylnonyl) and phenyl phosphite, etc.;

[0147] - the phenyl 1,3-dione family, used as heat stabilizers, such as dibenzoylmethane (DBM), etc.;

[0148] - the family of organophosphates used as flame retardants, such as tris(2-ethylhexyl) phosphate, etc.

[0149] Any impurities present are products resulting from cross-contamination or degradation of additives.

[0150] The plastic material processed in the method according to the invention is generally solid (under normal temperature and pressure conditions), particularly in the form of solid particles. Thus, if the PVC material is initially in the form of production scrap, installation waste, or post-consumer waste—particularly in the latter case, the initial form of PVC-based products—it may first undergo a conditioning step (as described below) comprising at least one grinding or shredding step to form a PVC material in particle form. Depending on the recycling streams and / or networks from which this production scrap, installation waste, and / or end-of-life PVC-based products originate, the PVC waste may be ground and / or washed and / or undergo any other conditioning step as described below to form the PVC material in particle form suitable for the method according to the invention.For example, the PVC filler may advantageously be in the form of ground material, possibly washed, with a largest dimension less than or equal to 20 cm, preferably less than or equal to 10 cm, preferably less than or equal to 1 cm, and even more preferably less than or equal to 5 mm. The PVC filler may also advantageously be in the form of micronized solid, that is, in the form of particles preferably having an average size less than 1 mm, for example, between 10 micrometers (µm) and 800 micrometers (µm). The average size advantageously corresponds to the average diameter of the spheres circumscribing said particles.

[0151] Thus, the plastic feedstock which feeds the process according to the invention is advantageously in the form of particles, typically having an average size of between 10 pm and 20 cm, for example particles of the type of ground-up having an average size of between 1 mm and 20 cm, preferably between 1 mm and 10 cm, more preferably between 1 mm and 1 cm, even more preferably between 1 mm and 5 mm, or particles resulting from micronization (very fine grinding to produce a powder) of an average size of less than 1 mm, preferably between 10 pm and 800 pm.

[0152] As already mentioned, the PVC filler may also include impurities referred to here as external impurities, which are common impurities, often "macroscopic," such as glass, wood, cardboard, paper, metal, rubber, silicones, plastics other than PVC (e.g., PET, etc.), mineral elements, etc. Advantageously, the PVC filler comprises at most 50% by mass, preferably at most 30% by mass, preferably at most 10% by mass, and even more preferably at most 5% by mass of "macroscopic" impurities. A possible preliminary conditioning step may, in addition to granulating the aforementioned PVC filler, allow for the removal of all or part of these common impurities.

[0153] The various stages of the process according to the invention leading to the stream of purified PVC polymer(s) advantageously reusable, as well as to at least one final additive stream, are detailed in the following paragraphs.

[0154] Optional preliminary step of conditioning the PVC-based plastic filler

[0155] According to the invention, the process may include a preliminary conditioning step for the PVC feed, comprising at least one step of grinding, shredding, or micronizing the PVC feed to form a PVC feed in the form of solid particles as defined above, suitable for being sent to step a) of dissolution. This preliminary conditioning step may further include one or more steps mentioned in the following non-exhaustive list: grinding by micronization, sorting, further sorting, washing, drying, etc. Depending on the nature of the PVC feed being processed, the step or steps, as well as their frequencies and possible sequences, involved in the preliminary conditioning step are chosen by those skilled in the art so as to limit the quantity of external (i.e., use) impurities and to reduce the size of the solid elements initially composing the PVC feed.

[0156] For example, the preliminary conditioning step allows for the supply of PVC feedstock in the form of particles, such as washed, ground material, with an average size of 5 mm or less, preferably between 1 mm and 5 mm, and a content of impurities of use that is preferably no more than 10% by mass, and more preferably no more than 5% by mass. This pre-conditioned PVC feedstock can also be in the form of micronized solid particles, i.e., particles with an average size of less than 1 mm, for example, between 10 µm and 800 µm.

[0157] The preliminary step of conditioning the PVC charge may include a step of drying the PVC charge.

[0158] Biphasic solvent system

[0159] According to the invention, the process for recovering a purified PVC polymer stream from the plastic feed is based on the use of a unique biphasic solvent system comprising two immiscible liquid phases A and B, specific to the dissolution of the PVC-based plastic feed and to the separation by liquid-liquid extraction of the PVC polymer fraction and the additives and any impurities present in the plastic feed to be treated, and preferably also to the separation of families of additives from each other.

[0160] With reference to the two-phase solvent system used in the invention, a solvent is understood to mean an organic solvent.

[0161] The solvent system according to the invention comprises, and preferably consists of, two immiscible liquid phases A and B. It is particularly advantageously characterized in that:

[0162] - phase A and phase B each comprise an organic solvent or a mixture of organic solvents chosen from the same list consisting of ketones, amides, azines, esters, ethers, halogenated solvents (preferably chlorinated, brominated, fluorinated), hydrocarbons, sulfide solvents, and dihydrolevoglucosenone; the PVC polymer(s) of the PVC-based plastic filler;

[0163] - the two-phase solvent system is capable of solubilizing at least two families of additives;

[0164] - the partition coefficient of the PVC polymer(s) in the two-phase solvent system, defined as the ratio of the mass concentrations of the PVC polymer(s) dissolved in phase B and in phase A, tends towards zero, and the partition coefficient of said families of additives in the two-phase solvent system, defined as the ratio of the mass concentrations of said families of additives dissolved in phase B and in phase A, is greater than or equal to 0.05.

[0165] In particular, the solvent system constituting the two-phase system is composed of a phase A based on at least one organic solvent (i.e., an organic solvent or mixture of organic solvents), capable of solubilizing, preferably completely, at least 90% by weight of the PVC polymer(s), preferably at least 95% by weight, even more preferably at least 98% by weight, and even more preferably at least 99% of the PVC polymer(s) in the plastic filler to be treated, as well as at least two families of associated additives, and a phase B, immiscible with phase A, based on at least one organic solvent (i.e., an organic solvent or mixture of organic solvents) exhibiting little affinity for solubilization with said PVC polymer(s). Thus, the partition coefficient of the PVC polymer(s) in the two-phase solvent system tends towards zero.By tending towards zero, we mean in this context having a value approaching zero and in all cases at least less than or equal to 0.01, and preferably between 0 and 0.01.

[0166] By dissolution of the PVC polymer(s), we must understand any phenomenon leading to the obtaining of at least one polymer solution, that is to say a liquid constituting phase A comprising at least the PVC polymer(s) dissolved in said at least one solvent of phase A. The person skilled in the art is well acquainted with the phenomena involved in the dissolution of polymers, which include at least a mixing, a homogenization, a solvation, a disentanglement and a dispersion of the polymer chains and more particularly here of the PVC polymer chains.

[0167] Thus, at least one solvent for phase A is chosen, based on its physicochemical properties, for its ability to solvate, disentangle, and disperse the PVC polymer chains. In this regard, those skilled in the art can rely on knowledge of the Hildebrand and / or Hansen solubility parameters of solvents to define, with respect to these same parameters specific to PVC resins, the most suitable solvent for inclusion in the composition of phase A. More specifically, phase A comprises a solvent or a mixture of solvents, particularly organic(s), preferably chosen so that its Hansen parameters lie within the Hansen sphere of the targeted PVC polymer(s).Hansen's theory allows us to predict the solubility of a polymer, particularly a thermoplastic such as PVC, in a solvent. This is achieved by determining the Hansen parameters and solubility sphere for the solvent and polymer, respectively, as a function of several parameters, notably their polar, hydrogen bonding, and dispersion parameters. If a solvent or solvent mixture exhibits Hansen parameters within the Hansen sphere of the PVC polymer, then the PVC polymer should be at least partially, and preferably completely, soluble in that solvent or solvent mixture. By an equivalent but opposite argument, phase B comprises at least one solvent chosen to be a poor dissolving liquid for the PVC polymer(s) compared to phase A, in addition to being immiscible or only partially miscible with it.

[0168] Furthermore, the nature and proportion of said solvents entering into the composition of phases A and B are determined in such a way as never to induce the precipitation, even partial, of the PVC polymer(s).

[0169] In this regard, it is worth recalling that the precipitation of a PVC polymer is defined as the transition of macromolecules from a liquid to a solid state. The completely disentangled chains of the polymer regroup and create a solid. It is possible to verify the absence of precipitation by transparency, provided that no other insoluble molecules in the system interfere with the assessment. For example, if inorganic molecules insoluble in the solvent system are present in the plastic waste and initial solubilization has been carried out, the polymer solubilization will not be visible to the naked eye, and a mass balance can be used to confirm that all of the PVC polymer has indeed been solubilized.

[0170] Furthermore, the nature and proportion of the solvents constituting phases A and B are chosen so as to solubilize, at least partially, the additives and potential impurities of the PVC-based plastic filler according to the invention, such that these are distributed between phases A and B, regardless of the specific distribution. Following the same principle as explained above, the solubilization of the additives and potential impurities is understood to mean the dispersion of said additives and potential impurities in the chosen solvents. As above, those skilled in the art can also refer to the Hildebrand and / or Hansen solubility parameters to estimate, based on the composition of the PVC filler, the distribution of the additives and associated potential impurities.

[0171] The partition coefficient of the additive(s) (and any impurities) in the solvent system, defined as the ratio of the mass concentrations of the additive(s) (and any impurities) dissolved in phase B and in phase A, is greater than or equal to 0.05. Preferably, the partition coefficient of the additive(s) in the solvent system is between 0.05 and 5, preferably between 0.5 and 5.

[0172] Preferably, the two-phase solvent system (i.e., the composition formed by the solvents of phases A and B of said system) is capable of solubilizing at least two families of PVC-based plastic filler additives included in the list consisting of:

[0173] - stabilizing additives chosen for example from metallic stearates of zinc (e.g. zinc stearate), calcium (e.g. calcium stearate), lead (e.g. lead stearate, dibasic lead stearate) or cadmium (e.g. cadmium stearate), epoxidized oils, organotins such as 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate of 2-ethylhexyl, mono, di and triphosphites as well as their derivatives, such as di(8-methylnonyl) and phenyl phosphite, or phenyl 1,3-diones such as dibenzoylmethane (DBM);- plasticizing additives chosen, for example, from among phthalates such as dioctyl or bis(2-diethylhexyl) phthalate (DOP or DEHP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), diisobutyl phthalate (DIBP), di-n-octyl phthalate (DNOP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl phthalate, isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, or from among other non-phthalic compounds such as bis(2-ethylhexyl) adipate (DEHA) or diisononyl ester of acid cyclohexane-l,2-dicarboxylic (DINCH), terephthalates such as dibutyl terephthalate or dioctyl terephthalate (DEHT), trimellitates such as trioctyl benzene-l,2,4-tricarboxylate or benzoates;

[0174] - lubricant additives chosen for example from paraffins and polyethylene waxes;

[0175] - anti-shock polymer or copolymer additives chosen from polyacrylates and methacrylate-butadiene-styrene;

[0176] - flame retardant additives chosen for example from organophosphates (OPFR) such as tris(2-ethylhexyl) phosphate, triphenyl phosphate (TPP), tri-o-cresyl phosphate or trixylenyl phosphate.

[0177] Preferably, the two-phase solvent system is capable of solubilizing at least two families of PVC-based plastic filler additives that are closely monitored by ECHA (ECHA, Investigation Report on PVC and PVC additives, version no. 1, 22 / 11 / 2023) and / or subject to REACH regulations, in particular additives selected from the group consisting of:

[0178] - the organotin family, used as stabilizers, such as 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate of 2-ethylhexyl (DOTE), etc.;

[0179] - metallic compounds used as stabilizers such as those based on lead and cadmium subject to REACH restrictions, such as lead and cadmium stearates, etc.;

[0180] - the family of ortho-phthalates, used as plasticizers, some of which are subject to regulations, such as dioctyl phthalate (DOP), bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di-isobutyl phthalate (DIBP), dipentyl phthalate (DPP), etc.;

[0181] - the terephthalate family, used as plasticizers, such as dibutyl terephthalate, etc.;

[0182] - the trimellitate family, used as plasticizers, such as trioctyl benzene-1,2,4-tricarboxylate, etc.;

[0183] - the benzoate family, used as plasticizers;

[0184] - the family of mono, di and triphosphites and their derivatives, used as heat stabilizers, such as di(8-methylnonyl) and phenyl phosphite, etc.; - the family of phenyl 1,3-diones, used as heat stabilizers, such as dibenzoylmethane (DBM), etc.;

[0185] - the family of organophosphates used as flame retardants, such as tris(2-ethylhexyl) phosphate, etc.

[0186] The list of specific molecules cited is not exhaustive and other examples of molecules for each family cited above are listed in the ECHA report mentioned above.

[0187] The two-phase solvent system may also be capable of solubilizing one or more impurities from the PVC-based plastic filler.

[0188] The partition coefficient of said impurity(ies) in the solvent system (ratio of mass concentrations of said impurity(ies) dissolved in phase B and in phase A) is preferably between 0.05 and 5, preferably between 0.5 and 5.

[0189] The organic solvent(s) for each of phases A and B of said two-phase solvent system are chosen from the list provided by:

[0190] - ketones, such as methyl ethyl ketone (MEK), diethyl ketone (DEK), 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone (MIBK), including cyclic ketones such as cyclopentanone or cyclohexanone;

[0191] - amides, such as N,N-diethyl formamide, including cyclic amides, such as 2-pyrrolidone or N-methyl-2-pyrrolidone;

[0192] - azines, such as pyridine, 4-aminopyridine, 2-aminopyridine, or 4-vinylpyridine;

[0193] - esters, such as methyl acetate, ethyl acetate, methyl propionate, n-butyl propionate, including cyclic esters such as y-butyrolactone (gamma-butyrolactone or GBL) or y-valerolactone (gamma-valerolactone or GVL);

[0194] - ethers, such as methoxycyclopentane (CPME) or diisopropyl ether, including cyclic ethers such as tetrahydrofuran (THF) or methyl tetrahydrofuran (MeTHF);

[0195] - halogenated solvents (chlorinated, brominated, fluorinated), in particular chlorinated solvents, such as dichloromethane or trichloromethane;

[0196] - hydrocarbons, such as xylene, cyclohexane, toluene, isohexane or n-heptane (heptane), and preferably cyclohexane, toluene, isohexane or n-heptane;

[0197] - sulfide solvents such as dimethyl sulfoxide (DMSO);

[0198] - dihydrolevoglucosenone (cyrene).

[0199] Preferably, phase A comprises, and may consist of, a mixture of at least two organic solvents: a major solvent, by weight (i.e. at least 50% by weight, relative to the total weight of said phase A), which is a sulfide solvent such as DMSO, and a minor solvent (i.e. less than 50% by weight, relative to the total weight of said phase A) which is selected from ketones, including cyclic ketones, and cyclic esters, preferably selected from MEK, DEK, 4-heptanone, 2,4-dimethyl-3-pentanone, MIBK, cyclopentanone, GBL, and GVL. In the case where phase A comprises (or is made up of) a mixture of two organic solvents, the content of the major solvent is advantageously strictly greater than 50% by weight, relative to the total weight of said phase A, and the content of the minor solvent is advantageously strictly less than 50% by weight, relative to the total weight of said phase A.

[0200] Preferably, phase A comprises, and may consist of, a mixture of at least three organic solvents:

[0201] - the major solvent, by weight (i.e. at least 50% by weight relative to the total weight of said phase A), which is DMSO,

[0202] - a first minor solvent chosen from among the cyclic ketones and esters, preferably from DEK, 4-heptanone, 2,4-dimethyl-3-pentanone, GBL and GVL, and

[0203] - a second minor solvent chosen from among hydrocarbons, preferably from xylene, cyclohexane, isohexane and n-heptane, more preferably from cyclohexane, isohexane and n-heptane.

[0204] Even more preferably, phase A comprises, and can be made up of, a mixture of three organic solvents:

[0205] - the major solvent, by weight (i.e. at least 50% by weight relative to the total weight of phase A), which is DMSO,

[0206] - a first minor solvent, which is DEK, preferably in a concentration chosen according to the other two solvents (the DMSO and heptane solvents), and

[0207] - a second minor solvent which is heptane, preferably in a content less than or equal to 15% by weight (relative to the total weight of phase A).

[0208] In one or more embodiments, phase A comprises, and preferably consists of:

[0209] - 50% to 70% weight of DMSO (relative to the total weight of phase A), preferably 55% to 65% weight of DMSO,

[0210] - 20% to 40% DEK weight (relative to the total weight of phase A), preferably 25% to 35% DEK weight,

[0211] - 5% to 15% weight of heptane (relative to the total weight of phase A), preferably 5% to 10% weight of heptane.

[0212] According to the invention, phase B comprises an organic solvent or a mixture of organic solvents chosen from the same list as that given for phase A.

[0213] Thus, phase B comprises, and preferably consists of, an organic solvent or a mixture of organic solvents chosen from the same list consisting of: - ketones, such as methyl ethyl ketone (MEK), diethyl ketone (DEK), 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone (MIBK), including cyclic ketones such as cyclopentanone or cyclohexanone;

[0214] - amides, such as N,N-diethyl formamide, including cyclic amides, such as 2-pyrrolidone or N-methyl-2-pyrrolidone;

[0215] - azines, such as pyridine, 4-aminopyridine, 2-aminopyridine, or 4-vinylpyridine;

[0216] - esters, such as methyl acetate, ethyl acetate, methyl propionate, n-butyl propionate, including cyclic esters such as γ-butyrolactone (GBL) or γ-valerolactone (GVL);

[0217] - ethers, such as methoxycyclopentane (CPME) or diisopropyl ether, including cyclic ethers such as tetrahydrofuran (THF) or methyl tetrahydrofuran (MeTHF);

[0218] - halogenated solvents (chlorinated, brominated, fluorinated), in particular chlorinated solvents, such as dichloromethane or trichloromethane;

[0219] - hydrocarbons, such as cycohexane, toluene, isohexane or n-heptane;

[0220] - sulfide solvents such as dimethyl sulfoxide (DMSO);

[0221] - dihydrolevoglucosenone (cyrene).

[0222] Preferably, phase B comprises, and may consist of, a mixture of at least two organic solvents: a major solvent, by weight (i.e. at least 50% by weight) selected from hydrocarbons, preferably selected from xylene, cyclohexane, isohexane and n-heptane, and more preferably selected from cyclohexane, isohexane and n-heptane, and a minor solvent (i.e. less than 50% by weight relative to the total weight of phase B) selected from ketones, including cyclic ketones, and cyclic esters, preferably selected from MEK, DEK, 4-heptanone, 2,4-dimethyl-3-pentanone, MIBK, cyclopentanone, GBL, and GVL.In the case where phase B comprises (or is made up of) a mixture of two organic solvents, the content of the major solvent is advantageously strictly greater than 50% by weight, relative to the total weight of said phase B, and the content of the minor solvent is advantageously strictly less than 50% by weight, relative to the total weight of said phase B.

[0223] Preferably, phase B comprises, and may consist of, a mixture of at least three organic solvents:

[0224] - the major solvent, by weight (i.e. at least 50% by weight relative to the total weight of said phase B) chosen from hydrocarbons, preferably from xylene, cyclohexane, isohexane and n-heptane, and more preferably from cyclohexane, isohexane and n-heptane,

[0225] - a first minor solvent selected from ketones, including cyclic ketones, and cyclic esters, preferably from DEK, 4-heptanone, 2,4-dimethyl-3-pentanone, GBL and GVL, and

[0226] - a second minor solvent chosen from among sulfide solvents such as DMSO. Even more preferably, phase B comprises, and may consist of, a mixture of three organic solvents:

[0227] - the major solvent, by weight (i.e. at least 50% by weight relative to the total weight of said phase B), which is heptane,

[0228] - the first minor solvent, which is DEK, preferably in a concentration chosen based on the other two (the heptane concentration and the DMSO concentration), and

[0229] - the second minor solvent which is DMSO, preferably at a content less than or equal to 15% by weight (relative to the total weight of said phase B).

[0230] In one or more embodiments, phase B comprises, and preferably consists of:

[0231] - 50% to 70% heptane by weight (relative to the total weight of phase B), preferably 55% to 65% heptane by weight,

[0232] - 20% to 40% DEK weight (relative to the total weight of phase B), preferably 25% to 35% DEK weight,

[0233] - 5% to 15% weight of DMSO (relative to the total weight of phase B), preferably 5% to 10% weight of DMSO.

[0234] The compositions of phases A and B of the solvent system given above, in particular the preferred mixture compositions of at least two or three solvents for each phase described above, are advantageously combined together.

[0235] For example, according to one or more embodiments, the solvent system comprises:

[0236] - phase A comprising a mixture of three organic solvents, of which a major solvent is DMSO, preferably in a content of between 50% and 70% by weight (relative to the total weight of said phase A), a first minor solvent, DEK, preferably in a content chosen according to the other two (that of DMSO and that of heptane), and more preferably in a content of between 20% and 40% by weight (relative to the total weight of said phase A), and a second minor solvent, heptane, preferably in a content of between 5% and 15% by weight (relative to the total weight of said phase A), and

[0237] - Phase B comprises a mixture of three organic solvents, including a major solvent, heptane, preferably in a concentration of between 50% and 70% by weight (relative to the total weight of said phase B); a minor solvent, DEK, preferably in a concentration chosen based on the other two (heptane and DMSO), and more preferably in a concentration of between 20% and 40% by weight (relative to the total weight of said phase B); and a minor solvent, DMSO, preferably in a concentration of between 5% and 15% by weight (relative to the total weight of said phase B). Furthermore, phases A and B of the solvent system used in the process according to the invention have, by definition, different densities, such that one is "above" the other when these two phases are placed in a fixed container.The lower-density "top" phase is called the "light phase." Conversely, the higher-density "bottom" phase is called the "heavy phase." Depending on the chemical compositions chosen for phases A and B of the two-phase solvent system, phases A and B can act as the light and heavy phases, respectively, and vice versa. Advantageously, the density difference between phase A and phase B is preferably greater than or equal to 20 kg / m³. 3 , preferably greater than or equal to 50 kg / m 3 , and very preferably greater than or equal to 100 kg / m 3 .

[0238] Preferably, phase A is denser than phase B.

[0239] In the case of implementation of liquid-liquid extraction in step b) by CPC, as explained later, phase A is defined as the so-called stationary phase of the CPC device, and phase B is defined as the mobile phase.

[0240] Step a) of dissolution

[0241] The process according to the invention comprises a dissolution step (a) in which the PVC-based plastic filler, advantageously in the form of particles, is contacted with a dissolving liquid consisting of phase A of the two-phase solvent system, to obtain at least one, preferably a single, crude polymer solution. This step advantageously allows the dissolution of at least some, preferably all, of the PVC polymer(s) contained in the plastic filler. This step also allows the dissolution of additives and any impurities contained in the plastic filler, in particular at least two families of additives.

[0242] Step a) of dissolving the PVC charge is carried out preferably at a dissolution temperature between the ambient temperature Tamb (typically 20°C ± 5°C) and 200°C, preferably between 20°C and 200°C, preferably between 40°C and 180°C, more preferably between 60°C and 150°C, and advantageously at a dissolution pressure between atmospheric pressure (i.e. 0.101325 MPa) and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, more preferably between atmospheric pressure and 2.0 MPa. The operating conditions of pressure and temperature are thus chosen so as to maintain the dissolving liquid, at least in part and preferably in whole, in a liquid state, while the soluble fraction of the PVC charge, in particular the PVC polymers and at least part of the additives and possible impurities, is advantageously dissolved at least in part and preferably in whole.Advantageously, the temperature and pressure conditions of step a) dissolution are adjusted so that the mixture (dissolving liquid + PVC polymer(s)) is monophasic, with any insoluble additives and impurities potentially suspended in said mixture. Advantageously, step a) dissolution is carried out with a residence time of between 1 minute (min) and 10 hours (h), preferably between 1 h and 8 h, and more preferably between 4 h and 8 h. Residence time is understood as the residence time at the dissolution temperature and pressure, i.e., the time the plastic filler is used with the dissolving liquid at the dissolution temperature and pressure in step a).

[0243] Preferably, step a) is fed with said plastic feed and said dissolving liquid, such that the weight of PVC polymer(s) present in the plastic feed, relative to the weight of the dissolving liquid, is between 1% and 30% by weight of PVC polymer(s) (relative to the total weight of the crude polymer solution), preferably between 2% and 20% by weight, and even more preferably between 3% and 15% by weight.

[0244] Preferably, at step a), the plastic filler / phase A mass ratio is between 0.01 and 1.4, preferably between 0.01 and 0.4, more preferably between 0.03 and 0.2.

[0245] In order to allow contact between the dissolving liquid and the plastic filler, and consequently the dissolution in the dissolving liquid of at least some, preferably all, of the PVC polymers contained in the plastic filler, step a) of dissolution can employ various equipment. Thus, step a) can advantageously employ at least one dissolving unit, one mixing unit, and / or one conveying unit. This equipment (or devices) can be, for example, a static mixer, an extruder, a pump, a reactor, or a co-current or counter-current column. Conveying equipment, particularly for fluids such as liquids or solids, is well known to those skilled in the art. Without limitation, conveying equipment can include a compressor, a pump, an extruder, a vibrating tube, a screw conveyor, or a valve.The equipment may also include or be associated with heating systems (e.g., furnace, heat exchanger, tracing, etc.) to achieve the conditions necessary for dissolution. Specifically, step a) of dissolution may employ a reactor stirred by a mechanical stirring system and / or a recirculation loop and / or by fluidization, for example, a perfectly stirred batch or continuous reactor, or a rotary drum reactor.

[0246] Step a) of dissolution is fed at least by the plastic filler and the dissolving liquid, in particular in the form of one or more streams of the dissolving liquid, advantageously by means of one or more conveying devices. The PVC filler may be introduced as a stream of solid particles separate from the stream(s) of dissolving liquid. Some or all of the PVC filler may also be fed into step a) mixed with some or all of the dissolving liquid, in particular as a suspension of solid particles in the liquid solvent, the remainder of the solvent and / or plastic filler, if any, being able to be fed into step a) separately. Step a) may be fed continuously or discontinuously with said plastic filler and / or said dissolving liquid, mixed or separately.

[0247] Preferably, step a) of dissolution is carried out in a stirred reactor using a mechanical stirring system and / or a recirculation loop and / or fluidization and / or ultrasound, for example, a perfectly stirred batch or continuous reactor, or a rotary drum reactor. Furthermore, the introduction of the PVC feedstock as a stream of solid particles, independent of the dissolution liquid stream(s), is preferred.

[0248] Advantageously, the dissolving liquid, i.e. phase A of the two-phase solvent system, used in step a) comprises, preferably consists of, fresh solvent, i.e. a solvent or mixture of solvents forming phase A never before used in the process (or a fresh solvent top-up) and / or a recycled phase A stream from a later step of the process, in particular from at least part of recovery step c).

[0249] According to the invention, said step a) of dissolution yields at least one, preferably a single, polymer solution, referred to herein as the crude polymer solution, comprising at least the dissolving liquid, i.e., phase A, and at least the PVC polymer(s) dissolved in said solvent. The crude polymer solution also comprises soluble additives also dissolved in the dissolving liquid, in particular at least two families of additives, and optionally impurities, soluble or insoluble in phase A, as well as optionally insoluble additives that remain in suspension.

[0250] Optional step a') of separation of insolubles

[0251] The process according to the invention may optionally include a step a') for separating insolubles from the crude polymer solution, in particular by solid-liquid separation, advantageously located upstream of the liquid-liquid extraction step b). This step a') for separating insolubles advantageously allows, when integrated into the process according to the invention, the separation of an insoluble fraction, which includes at least some, and preferably all, of the additives and any insoluble impurities suspended in the crude polymer solution obtained from step a), before it is sent to the liquid-liquid extraction step b). The insolubles removed during the insolubles separation step a') are, for example, additives initially present in PVC plastics (pigments, fillers, other polymers, etc.).), usage impurities (mineral compounds, glass, wood, paper, metal, other polymers) and / or degradation products, as described above in this description.

[0252] Step a') of separating the insolubles thus makes it possible, when integrated into the process according to the invention, to obtain a crude polymer solution, which can be called a clarified polymer solution, which is a polymer solution from which at least a part, preferably all, of the insolubles have been removed. Preferably, step a') also makes it possible to obtain an insoluble fraction.

[0253] When implemented, this separation step a') advantageously allows, in addition to the removal of at least some of the insoluble compounds, the limitation of operational problems, particularly clogging and / or erosion, in downstream process steps, while also contributing to the purification of the PVC feedstock. Preferably, the process according to the invention comprises a separation step a') of the insolubles.

[0254] Advantageously, the insoluble separation step, when implemented, is located upstream of step b) liquid-liquid extraction, and typically downstream of step a) dissolution.

[0255] Step a') of separating the insolubles is advantageously carried out under temperature and pressure conditions close to those of step a). Very advantageously, step a') of separating the insolubles is carried out under the temperature and pressure conditions of step a) of dissolution, as defined above. Thus, very advantageously, step a') is carried out at a temperature between ambient temperature Tamb (typically 20°C ± 5°C) and 200°C, preferably between 20°C and 200°C, preferably between 40°C and 180°C, more preferably between 60°C and 150°C, and advantageously at a pressure between atmospheric pressure (i.e., 0.101325 MPa) and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, more preferably between atmospheric pressure and 2.0 MPa.

[0256] When integrated into the process, step a') of insoluble separation is preferably fed by the crude polymer solution from step a).

[0257] Advantageously, the optional step a') may implement a section comprising at least one solid-liquid separation device, for example, a separator vessel, a decanter, a decanter centrifuge, a centrifuge, a filter, a sand filter, a tangential flow filter (particularly one using a membrane), and / or a depth filter (possibly with filter aids such as diatomaceous earth or sand), an eddy current separator, an electrostatic separator, a triboelectric separator, preferably a decanter, a filter, a sand filter, and / or an electrostatic separator. Advantageously, a self-cleaning filter may be used, with cleaning or unclogging to remove insolubles being carried out using a solvent stream.

[0258] Removing the insoluble fraction may require the use of equipment for transporting and potentially removing any solvent that may be impregnated in the separated insoluble fraction. For example, step a') may employ a conveyor, vibrating tube, screw conveyor, extruder, or stripper. Step a') may therefore employ equipment for transporting the insoluble fraction and / or for removing any solvent that may be carried along with the separated insoluble fraction. Advantageously, at least some of the solvent carried along with the separated insoluble fraction is recovered and recycled within the process.

[0259] In one particular embodiment, step a') of insoluble separation uses at least two, and generally fewer than five, solid-liquid separation units in series and / or in parallel. The presence of at least two solid-liquid separation units in series improves the removal of insolubles, while the presence of units in parallel facilitates the maintenance of said units and / or cleaning operations.

[0260] Some insoluble additives, particularly certain pigments and mineral fillers, commonly added during polymer formulation, can be introduced as particles smaller than 1 µm. This is the case, for example, with titanium dioxide, calcium carbonate, and carbon black. In one embodiment, the insoluble separation step (a') advantageously uses an electrostatic separator, which allows for the efficient removal, at least partially, of insoluble particles smaller than 1 µm. In another embodiment, the insoluble separation step (a') uses a sand filter to remove particles of various sizes, including those smaller than 1 µm.According to yet another embodiment, step a') of separating insolubles uses a tangential filter including a membrane and / or a depth filter, possibly in the presence of filtration aids such as diatomaceous earth.

[0261] According to the invention, said optional step a') of insoluble separation allows, when integrated into the process, the obtaining of at least one clarified polymer solution comprising at least the dissolving liquid and at least the PVC polymer(s) dissolved in said solvent and also at least two families of additives dissolved in said solvent. Thus, at least a part, and preferably all of the additives, and any insoluble impurities potentially present in suspension in the crude polymer solution obtained at the end of step a) of the process according to the invention, is removed from the crude polymer solution in step a'), before it is sent to step b).

[0262] Step b) Liquid-liquid extraction

[0263] According to the invention, the crude polymer solution, optionally freed of insolubles in step a') (clarified polymer solution) is sent to a liquid-liquid extraction step b), in at least one zone, in the presence of a single extraction liquid consisting of phase B of the biphasic solvent system, to obtain a purified polymer solution and at least one final additive stream comprising at least two families of additives.

[0264] In step b), no solvent other than those of phases A and B of the solvent system is used to obtain the purified polymer solution and said at least one final additive stream comprising at least two families of additives.

[0265] In general, liquid-liquid extraction is used to preferentially extract one or more solutes from a liquid feed in order to valorize the product (solute) or purify the liquid feed. This step relies on the use of an immiscible or partially miscible extraction liquid, chosen so that the compounds to be extracted, called solutes, have a preferential affinity for the extraction liquid. This step is carried out in equipment that facilitates the dispersion of one phase into the other, for example, in the form of droplets. As is known to those skilled in the art, the efficiency of extracting a compound i depends on the partition coefficient of that compound and the ratio between the flow rate of the extraction liquid and the flow rate of the liquid feed containing compound i.

[0266] According to the invention, a purification of the PVC-based plastic filler is carried out during step b) of liquid-liquid extraction, said plastic filler being in the form of the crude polymer solution, possibly freed from insolubles in step a') (clarified polymer solution), by one or more liquid-liquid extraction operations, in order to separate the PVC polymer(s) from at least two families of additives, by means of a single extraction liquid consisting of phase B of the biphasic solvent system, with a view to recycling on the one hand at least the PVC polymer(s), and on the other hand possibly its additives in mixture or separated, at least partially, by family.

[0267] In general, in the process according to the invention, liquid-liquid extraction covers any contact between phase A and phase B with exchange of compounds from the crude polymer solution, possibly freed of insolubles in step a') (clarified polymer solution), between said phases A and B.

[0268] Preferably, step b) is carried out at a temperature between ambient temperature Tamb (typically 20°C ± 5°C) and 200°C, preferably between 20°C and 200°C, preferably between 40°C and 180°C, more preferably between 60°C and 150°C, and advantageously at a pressure between atmospheric pressure (i.e., 0.101325 MPa) and 11.0 MPa absolute, preferably between atmospheric pressure and 5.0 MPa absolute, more preferably between atmospheric pressure and 2.0 MPa absolute. Under these operating conditions, the PVC polymer(s), as well as the at least two families of additives, remain dissolved in the solvent system. Preferably, the temperature and pressure conditions of step b) are the same as those of dissolution step a).

[0269] Figure 1 schematically illustrates the principle of a liquid-liquid extraction as carried out in step b) of the process according to the invention.

[0270] A feedstock 1, corresponding to the crude polymer solution, possibly freed of insolubles in step a') (clarified polymer solution), comprising a dissolving liquid consisting of phase A of the two-phase solvent system and the PVC polymer(s) of the plastic feedstock dissolved in phase A, as well as at least two families of additives Ad1 and Ad2 solubilized in said phase A, is brought into contact in at least one zone with a single extraction liquid 4 consisting of phase B of the two-phase solvent system. The extraction liquid is chosen such that the additives, and any impurities, to be extracted as solutes, have a preferential affinity for said extraction liquid, unlike the PVC polymer(s), as detailed previously, and such that there is a density difference between phase A and phase B as already defined above in the detailed description of the solvent system.

[0271] During liquid-liquid extraction in this zone, the Adl and Ad2 additive families, whose flows are represented by the gray arrows in Figure 1, as in the other figures (solid line for the first Adl additive family and dashed line for the second Ad2 additive family), pass from phase A to phase B due to their preferential affinity for phase B, notably estimated by their partition coefficient. It is thus possible to extract from this zone a purified polymer solution 3 (raffinate) containing phase A and the PVC polymer(s), and a final additive flow containing phase B and at least two of the aforementioned Adl and Ad2 additive families (extract).

[0272] Step b) is carried out in at least one zone, said zone being defined in this description between at least one injection point of a flow containing phase A or phase B and at least one withdrawal point of a flow containing phase A or phase B. Each zone is characterized by constant implementation parameters and / or operating conditions of the liquid-liquid extraction (e.g. number of theoretical trays, incoming flow rate ratios, temperature etc.).

[0273] Preferably, phase A is the so-called heavy phase, i.e., one with a higher density than the light phase, which is preferably phase B. This preference is clearly illustrated in Figures 2 to 7, where phase B, shown in white in the zone(s) (and conversely, phase A is shown in black), is introduced at the bottom of the zone, typically at the bottom of a liquid-liquid extraction column. The present invention also covers the reverse case, where phase A is the light phase and phase B is the heavy phase.

[0274] In step b), the final additive stream(s) produced advantageously include phase B in which the additives are extracted, but depending on the implementation of step b), some final additive streams may also include essentially phase A associated with a family of additives.

[0275] According to the possible implementations of step b), said at least one final additive stream comprises phase B and includes at least both families of additives, or comprises one of the two families of additives and in this case at least one other final additive stream is produced, which contains the other of the two families of additives as well as phase B or phase A. By additive stream comprising phase A or phase B, it is understood that the solvent composition(s) of said final additive stream is either that of phase A or that of phase B.

[0276] The separation by liquid-liquid extraction in step b) can take several forms, and is illustrated, in a non-limiting way, in figures 2 to 7.

[0277] Step b) can be carried out in a single area, as illustrated in Figure 2, to form the purified polymer solution and a single final additive stream comprising said at least two families of additives.

[0278] The liquid-liquid extraction separation in step b) can be multi-zone, as illustrated in Figures 3 to 7, and thus carried out in at least two zones to form the purified polymer solution and a single final additive stream comprising at least two families of additives (Figure 4), or at least two final additive streams, each containing one of the two families of additives (Figures 3 and 5 to 7). Each zone corresponds to a given liquid-liquid extraction substep, with these zones and substeps preferably employing different phase B / phase A flow ratios and a variable number of theoretical NET plates (also called theoretical stages). In the following description of step b), possible substeps are numbered in an order that is not a function of the actual order: for example, a step b.3) does not follow a step b.2), and the numbering of the substeps is simply used to distinguish the substeps from one another.

[0279] The liquid-liquid extraction device implemented in step b) therefore comprises at least one zone. Each zone may include an injection (feed) point for a charge comprising phase A (the term "charge" being used generically to designate a stream containing phase A and sent into a liquid-liquid extraction zone, and not necessarily containing the PVC polymer(s) of the PVC-based plastic charge), in said zone, preferably at the head of the zone, and an injection (feed) point for the stream containing extraction liquid (phase B), preferably at the bottom of the zone, and the charge and the stream containing extraction liquid are brought into contact, preferably in counter-current flow, within the zone.

[0280] Also, each zone may include a withdrawal point of a stream containing phase A, preferably at the bottom of the zone, which may be a "refined", i.e. a stream containing phase A and in which compounds may have been "removed" during the liquid-liquid extraction, and a withdrawal point of a stream containing phase B, preferably at the top of the zone, which may be an "extract", i.e. a stream containing phase B and in which compounds may have been "gained" during the liquid-liquid extraction.

[0281] For convenience, the mass ratio of solvent / charge of a given zone will be defined as the ratio between the mass of the flux containing phase B sent into said zone and the mass of the charge flux sent into said zone, i.e. the flux containing phase A sent into said zone.

[0282] The liquid-liquid extraction system implemented in step b) therefore comprises at least one zone, which zone may include one or more pieces of equipment for performing the liquid-liquid extraction. The zone(s) in step b) include at least one piece of liquid-liquid extraction equipment selected from

[0283] - gravity columns equipped with perforated trays;

[0284] - gravity columns equipped with bulk or structured packing;

[0285] - gravity columns equipped with trays and bulk or structured packing;

[0286] - agitated columns;

[0287] - pulsed columns;

[0288] - cascade mixer-decanters;

[0289] - centrifugal partition chromatography (CPC) devices; and

[0290] - centrifugal extractors.

[0291] These equipment and their operation are well known to those skilled in the art. Preferably, the said zone includes, for carrying out liquid-liquid extraction, at least one stirred column or pulsed column, allowing the implementation of numerous theoretical stages, for example up to 15 theoretical stages (portions, often fictitious, of space, whose outgoing flows are in thermodynamic equilibrium).

[0292] According to one or more embodiments, said zone includes, for carrying out step b) of liquid-liquid extraction, a CPC device. Such a CPC device comprises a column incorporating a succession of cavities, preferably parallelepiped or cylindrical, connected to each other by channels, which comprise 2 immiscible liquid phases such as those forming the biphasic solvent system used in the process according to the invention.

[0293] A CPC device that can be implemented in step b) of the process according to the invention may comprise interconnected partition cells arranged radially around a rotor that rotates all the interconnected cells. A constant centrifugal force field is generated by the rotation of the device, which maintains one of the two immiscible phases of the two-phase solvent system within said device, preferably phase A, referred to as the stationary phase, while the other liquid phase, preferably phase B, referred to as the mobile phase, flows through the stationary phase in an "upward" or "downward" direction. Depending on the density of the stationary phase, the mobile phase may flow through said stationary phase in an upward or downward direction.More specifically, if the stationary phase is the densest (heavy phase), the pumping of the light mobile phase occurs in an upward direction (opposite to the centrifugal force), in order to promote the maintenance of the stationary phase within the CPC device. Conversely, if the stationary phase is the least dense (light phase), the pumping of the heavy mobile phase occurs in a downward direction (in the direction of the centrifugal force), also to promote the maintenance of the stationary phase within the CPC device.

[0294] Preferably, the solvent system used and implemented in a CPC device in step b) is such that phase A, which is the stationary phase, is also the heavy phase, which favors an operation of the CPC device according to an upward circulation mode of the mobile phase.

[0295] The mobile phase "percolates" in a sort of way, in a "spray" state, through the stationary phase.

[0296] According to this or these implementations where a CPC device is used in step b), it is thus possible to separate the PVC polymer(s) from at least two families of additives with a single extraction liquid (i.e. phase B) in at least one column comprising a series interconnection of at least one set of partition cells in which the stationary phase, e.g. phase A, is maintained by centrifugal effect and the mobile phase, e.g. phase B, flows by percolation through said stationary phase, to separate the additives retained in the mobile phase comprising phase B, and produce a purified polymer solution and at least one final additive stream comprising at least two families of additives.

[0297] During liquid-liquid extraction using a CPC device, the mobile phase passes through the stationary phase. This is an elution phase during which the compounds are separated from the crude polymer solution, possibly freed of insolubles in step a') (clarified polymer solution).

[0298] It is possible to collect the effluent recovered from the CPC device during this elution phase as different liquid fractions over time, in cases where the aim is to separate the additives by major chemical families. This separation is achieved through the progressive elution of these additives in the mobile phase, based on their partition coefficient in the solvent system. In this latter case, step b), implemented in a CPC device, yields more than two final additive streams, each containing a specific additive family.

[0299] Figure 2 illustrates a first possible implementation of the invention, corresponding to a minimal arrangement, where step b) is carried out in a single zone Z0 to form the purified polymer solution and a single final additive stream comprising said at least two families of additives, e.g. phthalates and OPFRs.

[0300] The crude polymer solution 1 is introduced into zone Z0 through an injection point advantageously located at the head of said zone, and is contacted countercurrently or co-currently, preferably countercurrently as shown, with an extraction liquid stream 40, i.e., phase B, preferably introduced through an injection point located at the bottom of said zone. The at least two families of additives Adl and Ad2 are extracted in phase B (see additive flows represented by the gray arrows), and a final additive stream 2 comprising phase B and said at least two families of additives ("B+Adl+Ad2") is withdrawn from said zone Z0, preferably through an outlet point located at the head of said zone. The purified polymer solution 3 comprising phase A and the PVC polymer(s) ("A+P") is withdrawn from said zone Z0, preferably through a withdrawal point located at the bottom of said zone.

[0301] Preferably, the solvent / load mass ratio (i.e. here extraction liquid 40 / crude polymer solution 1, possibly freed of insolubles in step a') (clarified polymer solution)) is between 1 and 15, preferably between 1 and 10, and more preferably between 1 and 8.

[0302] Preferably, the number of theoretical floors is between 1 and 15, preferably between 1 and 10, and more preferably between 1 and 8.

[0303] Preferably, the flow rate of crude polymer solution 1 (or clarified polymer solution) is between 0.1 t / h and 380 t / h, preferably between 0.3 t / h and 125 t / h, more preferably between 0.6 t / h and 20 t / h. Figure 3 illustrates a second possible embodiment of the invention in which step b) is carried out in two coupled extraction zones Z1 and Z2.

[0304] In this description, the term "extraction zone" refers to a zone in which the liquid-liquid extraction step (b) is carried out, and which receives a flow of extraction solvent (41, 42), i.e., a flow consisting essentially of phase B. By consisting essentially of phase B, it is understood that the extraction solvent flow comprises more than 95% by weight of phase B, preferably more than 98%, or even more than 99% by weight of phase B, and even more preferably 100% by weight of phase B. The term "coupled" with respect to the zones in step (b) means that the zones are configured so that at least one liquid flow passes from one to any other of the other zones, for example, that they are connected by means of conduits, valves, etc.

[0305] According to this implementation, step b) comprises: b) a liquid-liquid extraction substep of the crude polymer solution 1 in the presence of the extraction liquid (stream 41) in a first extraction zone Z1 to obtain an intermediate polymer(s) solution 5 and a first final additive stream 21 (“B+Adl”) comprising a first family of additives Adl, e.g. phthalates; b.2) a liquid-liquid extraction substep of said intermediate polymer solution 5 in the presence of the extraction liquid (stream 42) in a second extraction zone Z2 fluidically coupled to said first extraction zone Z1, to obtain the purified polymer solution 3 (“A+P”) and a second final additive stream 22 (“B+Ad2”) comprising a second family of additives Ad2, e.g. OPFRs.

[0306] This implementation allows, on the one hand, the separation of the PVC polymer(s) from at least two families of additives, e.g. phthalates and OPFRs, but also provides two distinct streams of final additives (e.g. phthalates on one side and OPFRs on the other) with the aim of separately valorizing these additives.

[0307] In the first zone Zl, the Adl additives are extracted from the extraction liquid, i.e., phase B (see solid gray arrows). The resulting extract, i.e., the first final additive stream 21, therefore comprises phase B and the Adl additive family. It may also contain traces of Ad2 family additives and PVC polymer(s). The raffinate formed in the extraction zone Zl, i.e., the intermediate polymer(s) solution 5, comprises phase A, the Ad2 additive family, the PVC polymer(s), and possibly traces of Adl family additives, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight, or even less than 0.01% by weight of Adl family additives.

[0308] The first extraction zone Zl and its operation are configured to preferentially extract a family of additives, e.g., phthalates, and to achieve the required purity specifications. Preferably, the flow rate of extraction liquid 41 in the extraction zone Zl is minimized so as to obtain at the outlet of said zone Zl a first final additive stream 21 that is as concentrated as possible and to minimize investment costs (e.g., size of a column forming zone Zl) and operating costs (CAPEX and OPEX).

[0309] Preferably, the solvent / load mass ratio in the first extraction zone Zl (i.e. extraction liquid 41 / crude polymer solution 1, possibly freed of insolubles in step a') (clarified polymer solution)) is between 1 and 10, preferably between 1 and 8, and more preferably between 1 and 5.

[0310] Preferably, the number of theoretical stages in the first extraction zone Zl is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10. Preferably, the flow rate of crude polymer solution (or clarified polymer solution) in the first extraction zone ZI is between 0.1 t / h and 380 t / h, preferably between 0.3 t / h and 125 t / h, more preferably between 0.6 t / h and 20 t / h.

[0311] In the second zone Z2, the Ad2 additives are extracted from the extraction liquid, i.e., phase B (see gray dashed arrows). The resulting extract, i.e., the final second additive stream 22, therefore comprises phase B and the Ad2 additive family. It may also contain traces of Adl family additives and PVC polymer(s). The raffinate formed in the extraction zone Z2, i.e., the purified polymer solution 3, comprises phase A and the PVC polymer(s), and possibly traces of additives from at least the Adl and Ad2 families, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight or even less than 0.01% of said additives.

[0312] Preferably, the solvent / load mass ratio in the second extraction zone Z2 (i.e. extraction liquid 42 / intermediate polymer solution 5) is between 1 and 15, preferably between 1 and 10, and more preferably between 1 and 5.

[0313] Preferably, the number of theoretical floors in the second extraction zone Z2 is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0314] Advantageously, the solvent / load mass ratio in the second extraction zone Z2 (extraction liquid 42 / intermediate polymer solution 5) is greater than or equal to that of the first extraction zone ZI (extraction liquid 41 / crude polymer solution 1 (or clarified polymer solution)).

[0315] Figure 4 illustrates a third possible implementation of the invention in which step b) is carried out in two coupled zones formed by an extraction zone Z and a counter-extraction zone C.

[0316] The term "counter-extraction" can be used in this description to refer to the transfer of compounds such as the PVC polymer(s) and additives from phase B to phase A, during step b). Thus, a so-called counter-extraction zone is a zone in which a transfer of PVC polymer(s) and / or additives from phase B to phase A takes place.

[0317] According to this third implementation, step b) includes: b.3) a liquid-liquid extraction substep in an extraction zone Z of a feed formed by a mixture of the crude polymer solution 1 (or the clarified polymer solution) with a first phase stream A 6, in contact with the extraction liquid (stream 43), to obtain the purified polymer solution 3 (“A+P”) and an intermediate extract 7 comprising said at least two families of additives; b.4) a liquid-liquid extraction substep of said intermediate extract 7 in a counter-extraction zone C to counter-extract the PVC polymer(s) of said intermediate extract 7 in contact with an initial phase A stream 8 and obtain the final additive stream 2 comprising said at least two families of additives (“B+Adl+Ad2”), e.g. phthalates and OPFRs, and said first phase A stream 6 mixed with the crude polymer solution 1 (or the clarified polymer solution) to form the feed sent to step b.3).

[0318] This third implementation allows on the one hand to separate the PVC polymer(s) from at least the two families of additives, e.g. phthalates and OPFR, but also to limit the losses of PVC polymer(s) which could be very weakly dissolved in phase B.

[0319] In extraction zone Z, additives from both families Adl and Ad2 are extracted from the extraction liquid, i.e., phase B (see solid and dashed gray arrows). The resulting extract, i.e., the intermediate extract 7, therefore comprises phase B and at least both families of additives Adl and Ad2. The raffinate formed in extraction zone Z, i.e., the purified polymer solution 3, comprises phase A and the PVC polymer(s), and possibly traces of additives from at least both families Adl and Ad2, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight, or even less than 0.01% by weight of said additives. Extraction zone Z and its operation are configured to "purify" phase A of the additives initially present.

[0320] Preferably, the solvent / feed mass ratio in the extraction zone Z (i.e. extraction liquid 43 / feed (crude polymer solution 1 (or clarified polymer solution) + first phase flow A 6) is between 0.5 and 20, preferably between 0.5 and 10, and more preferably between 1 and 5.

[0321] Preferably, the number of theoretical floors in the extraction zone Z is between 2 and 15, preferably between 2 and 12, and more preferably between 2 and 10.

[0322] Preferably, the flow rate of crude polymer solution 1 (or clarified polymer solution) in the extraction zone Z is between 0.1 t / h and 380 t / h, preferably between 0.3 t / h and 125 t / h, more preferably between 0.6 t / h and 20 t / h.

[0323] In the counter-extraction zone C, the PVC polymer(s) present in phase B of the intermediate extract 7, preferably introduced at the bottom of zone C, are counter-extracted in phase A. The counter-extraction zone C and its operation are configured to counter-extract the PVC polymer(s) and minimize associated losses. The resulting extract, i.e., the final additive stream 2, therefore comprises phase B and at least the two families of additives Adl and Ad2, advantageously without PVC polymer(s) or present in very low concentrations or even as traces, preferably less than 5% by weight, more preferably less than 1% by weight, and even more preferably less than 0.5% by weight or less than 0.1% by weight of PVC polymer(s) (relative to the total weight of the stream considered).The first phase A 6 flow, drawn from the counter-extraction zone C, preferably at the bottom of zone C, and sent to the extraction zone Z, includes the polymer(s) counter-extracted in zone C.

[0324] Preferably, the solvent / load mass ratio in the counter-extraction zone C (i.e. intermediate extract 7 / initial phase flow A 8) is between 1 and 50, preferably between 1 and 20, and more preferably between 2 and 10. Preferably, the number of theoretical stages in the counter-extraction zone C is between 1 and 10, preferably between 1 and 5, and more preferably between 1 and 3.

[0325] Advantageously, the solvent / feed mass ratio (extraction liquid 43 / feed formed by the sum of fluxes 1 and 6) in the extraction zone Z is lower than that of the counter-extraction zone C (intermediate extract 7 / initial flux of phase A 8).

[0326] Preferably, the theoretical number of floors in the counter-extraction zone C is smaller than the theoretical number of floors in the extraction zone Z.

[0327] According to this third implementation, it is possible to use a single piece of equipment to carry out sub-steps b.3) and b.4), i.e. the extraction zones Z and counter-extraction C can be part of a single liquid-liquid extraction equipment.

[0328] Figure 5 illustrates a fourth possible implementation of the invention in which step b) is carried out in two coupled zones formed by an extraction zone Z and a counter-extraction zone C, with intermediate withdrawal of a phase A flow.

[0329] According to this fourth implementation, step b) comprises: b.5) a liquid-liquid extraction substep in an extraction zone Z of a feedstock formed by mixing the crude polymer solution 1 (or the clarified polymer solution) with a first fraction 9 of a first phase stream A 6, in contact with the extraction liquid (stream 44), to obtain the purified polymer solution 3 (“A+P”) and an intermediate extract 7 comprising at least two families of additives; b.6) a liquid-liquid extraction substep of said intermediate extract 7 in a counter-extraction zone C to counter-extract the PVC polymer(s) of said intermediate extract 7 in contact with an initial phase stream A 8 and obtain a final first additive stream 23 (“B+Adl”) comprising a first family of additives Adl, e.g.phthalates, and said first phase A 6 stream, a first fraction 9 of which is mixed with the crude polymer solution (or clarified polymer solution) to be sent to the extraction zone Z in step b.5).

[0330] According to this implementation, the first phase A 6 flow exiting the counter-extraction zone C is divided to form the first fraction 9 (of the first phase A 6 flow) and a second complementary fraction (to fraction 9) constituting a second final additive flow 24 (“A+Ad2”) comprising at least the second family of additives Ad2 and phase A.

[0331] According to this implementation, it is possible to extract the additives of the second family Ad2, e.g., OPFRs, in the withdrawn stream 24. This is made possible, in particular, by the difference in the solvent / load mass ratio of the extraction zone Z and the counter-extraction zone C, and by the difference in the number of theoretical stages in these two zones. Compared to the third implementation shown in Figure 4, the number of theoretical stages in the counter-extraction zone C is advantageously greater in this fourth implementation, and the solvent / load mass ratio of the counter-extraction zone C is advantageously smaller.

[0332] This fourth implementation makes it possible to separate the PVC polymer(s) from at least the two families of additives, e.g. phthalates and OPFRs, but also to limit the losses of PVC polymer(s) which could be very weakly dissolved in phase B, while allowing two distinct streams of final additives (e.g. phthalates on one side and OPFRs on the other) in order to valorize these additives separately.

[0333] The liquid-liquid extraction device according to this implementation also includes means for dividing the first phase flow A 6 at the outlet of zone C.

[0334] In extraction zone Z, additives from both families Adl and Ad2 are extracted from the extraction liquid, i.e., phase B (see solid and dashed gray arrows). The resulting extract, i.e., the intermediate extract 7, therefore comprises phase B and at least both families of additives Adl and Ad2. The raffinate formed in extraction zone Z, i.e., the purified polymer solution 3, comprises phase A and the PVC polymer(s), and possibly traces of additives from at least both families Adl and Ad2, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight, or even less than 0.01% by weight of said additives. Extraction zone Z and its operation are configured to "purify" phase A of the additives initially present.

[0335] Preferably, the solvent / feed mass ratio in the extraction zone Z (i.e. extraction liquid 44 / feed (crude polymer solution 1 (or clarified polymer solution) + first fraction 9 of the first phase flow A 6) is between 1 and 10, preferably between 1 and 8, and more preferably between 1 and 5.

[0336] Preferably, the number of theoretical floors in the extraction zone Z is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0337] Preferably, the feed rate (crude polymer solution 1 (or clarified polymer solution)) in the extraction zone Z is between 0.1 t / h and 380 t / h, preferably between 0.3 t / h and 125 t / h, more preferably between 0.6 t / h and 20 t / h.

[0338] In the counter-extraction zone C, the PVC polymer(s) present in phase B of the intermediate extract 7, preferably introduced at the bottom of zone C, are counter-extracted in phase A. The additives of the second family Ad2 are also counter-extracted in phase A. The counter-extraction zone C and its operation are indeed configured so as to counter-extract the PVC polymer(s) and minimize the associated losses, as well as to counter-extract the additives of the second family Ad2. The extract formed, i.e. the final additive stream 23, therefore comprises phase B and the first family of additives Adl, advantageously without PVC polymer(s) or present in very low levels or even in trace amounts, preferably less than 5% by weight, more preferably less than 1% by weight, even more preferably less than 0.5% by weight or less than 0.1% by weight of PVC polymer(s) (relative to the total weight of the stream considered).

[0339] Upon exiting the counter-extraction zone, the division of the first phase A stream 6, preferably drawn from the bottom of zone C, produces the final second additive stream 24, which comprises phase A and the second family of additives Ad2, and possibly traces of additives from the first family Adl, e.g., phthalates (preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight), and PVC polymer(s) (preferably less than 5% by weight, more preferably less than 1% by weight, even more preferably less than 0.5% by weight or less than 0.1%). The first fraction 9 (complementary to fraction 24), having the same composition as the second additive stream 24, is mixed with the crude polymer solution (or the clarified polymer solution) to form the feedstock sent to the extraction zone Z.

[0340] Preferably, the solvent / load mass ratio in the counter-extraction zone C (i.e. intermediate extract 7 / initial phase flow A 8) is between 0.1 and 10, preferably between 0.2 and 8, and more preferably between 0.2 and 5.

[0341] Preferably, the number of theoretical floors in the counter-extraction zone C is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 8.

[0342] Advantageously, the solvent / feed mass ratio (extraction liquid 44 / feed: sum of flux 1 and fraction 9 of flux 6) in the extraction zone Z is greater than that of the counter-extraction zone C (intermediate extract 7 / initial flux of phase A 8).

[0343] Preferably, the theoretical number of floors in the counter-extraction zone C is smaller than the theoretical number of floors in the extraction zone Z.

[0344] According to this fourth implementation, it is possible to use a single piece of equipment to carry out sub-steps b.5) and b.6), i.e. the extraction zones Z and counter-extraction C can be part of a single liquid-liquid extraction equipment.

[0345] Figure 6 illustrates a fifth possible implementation of the invention in which step b) is carried out in three coupled zones formed by two extraction zones ZI and Z3 and a counter-extraction zone C.

[0346] According to this fifth implementation, step b) comprises: b.7) a liquid-liquid extraction substep in a first ZI (extraction zone) of a feedstock formed by mixing the crude polymer solution 1 (or the clarified polymer solution) with a first fraction 12 of a first phase A stream 11, in contact with extraction liquid (stream 45), to obtain the purified polymer solution 3 (“A+P”) and a first intermediate stream 13 comprising said at least two families of additives Adl and Ad2; b.8) a liquid-liquid extraction substep of said first intermediate stream 13 in contact with an initial phase A stream 8 in a second zone C, to counter-extract the PVC polymer(s) from said first intermediate stream 13 and separate the two families of additives between phases A and B, and obtain a final first additive stream 25 (“B+Adl”) comprising a first family of additives Adl, ephthalates, and a second phase A 10 stream comprising a second family of additives; b.9) a liquid-liquid extraction substep of the second phase A 10 stream in a third zone Z3 in contact with extraction liquid (stream 46), to form said first phase A 11 stream and a second intermediate stream 14 sent to the second zone C in step b.8).

[0347] According to this implementation, the first phase flux A 11 exiting the third zone Z3 is divided to form the first fraction 12 (of the first phase flux A 11) and a second fraction of the first phase flux A 11, complementary to the first fraction 12, constituting a second final additive flux 26 (“A+Ad2”) comprising the additives of the second family Ad2, e.g. OPFRs) and of phase A.

[0348] This fifth implementation allows the PVC polymer(s) to be separated from at least two families of additives, e.g. phthalates and OPFRs, but also provides two separate streams of final additives (e.g. phthalates on one side and OPFRs on the other) with the aim of separately valorizing these additives, as well as offering a more advanced separation than in the implementations presented previously, and limiting the losses of PVC polymer(s) which could be very weakly dissolved in phase B.

[0349] The liquid-liquid extraction device according to this implementation also includes means for dividing the first phase flow A 11 at the outlet of the third zone Z3.

[0350] In the first zone Zl, the additives from both families Adl and Ad2 are extracted from the extraction liquid, i.e., phase B (see solid and dashed gray arrows). The resulting extract, i.e., the first intermediate stream 13, therefore contains phase B and at least both families of additives Adl and Ad2. The raffinate formed in the first zone Zl, i.e. the purified polymer solution 3, comprises of phase A and the PVC polymer(s), advantageously without additives or possibly containing levels of additives of at least the two families Adl and Ad2 in trace amounts, in particular lower than those of the purified polymer solution of the previous configurations in relation to figures 2 to 5, in all cases preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight, or even less than 0.01% by weight of said additives (relative to the total weight of the stream considered).

[0351] The first zone Zl and its operation are configured so as to "purify" phase A of the additives initially present.

[0352] Preferably, the solvent / feed mass ratio in the first zone Zl (i.e. extraction liquid 45 / feed (crude polymer solution 1 (or clarified polymer solution) + fraction 12 of the first phase A 11 flow) is between 1 and 10, preferably between 1 and 8, and more preferably between 1 and 5. Preferably, the number of theoretical stages in the first zone Zl is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10. Preferably, the flow rate of crude polymer solution 1 (or clarified polymer solution) in the first zone ZI is between 0.1 t / h and 380 t / h, preferably between 0.3 t / h and 125 t / h, more preferably between 0.6 t / h and 20 t / h.

[0353] In the second zone C (counter-extraction zone), which is a counter-extraction zone, the PVC polymer(s) present in phase B of the first intermediate stream 13, preferably introduced at the bottom of zone C, are counter-extracted in phase A. The additives present in the second intermediate stream 14, also preferably introduced at the bottom of zone C, are separated between phases A and B; in particular, the additives of the second family Ad2 are counter-extracted in phase A. The counter-extraction zone C and its operation are configured to counter-extract the PVC polymer(s) and minimize associated losses, as well as to counter-extract the additives of the second family Ad2. The extract formed, i.e.The first final additive stream 25 therefore comprises phase B and the first family of additives Adl, advantageously without PVC polymer(s) or present in very low levels or even in trace amounts, preferably less than 5% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight of PVC polymer(s) (relative to the total weight of the stream considered). The first phase A stream 6, withdrawn from the counter-extraction zone C, preferably at the bottom of zone C, and sent to the extraction zone Z, comprises the polymer(s) counter-extracted in zone C. The second phase A stream 10, withdrawn from the second (counter-extraction) zone C, preferably at the bottom of the second zone C, and sent to the third zone Z3, comprises the polymer(s) counter-extracted in the second zone C, and the additives of the second family Ad2 counter-extracted in the phase A.

[0354] Preferably, the solvent / load mass ratio in the second zone C (i.e. flux 13 + 14 / initial flux of phase A 8) is between 0.1 and 10, preferably between 0.2 and 8, and more preferably between 0.2 and 5.

[0355] Preferably, the number of theoretical floors in the second zone C is between 1 and 20, preferably between 2 and 15, and more preferably between 2 and 10.

[0356] In the third zone Z3 (extraction zone), the additives of the first family Adl that may be present in the second phase A stream 10 are extracted into the extraction liquid, i.e., phase B. The resulting extract, i.e., the second intermediate stream 14, therefore comprises phase B and additives of the first family Adl, as well as possible traces of additives of the second family Ad2 and low levels of PVC polymer(s). The raffinate formed in the third zone Z3, i.e., the first phase A stream 11, comprises phase A, the PVC polymer(s) counter-extracted in the second zone C, and the additives of the second family Ad2 counter-extracted in the second zone C.

[0357] The first phase A 11 stream includes the PVC polymer(s) counter-extracted in counter-extraction zone C.

[0358] The third zone Z3 and its operation are configured so as to "purify" phase A of the additives of the first family of additives Adl present in the flow 10, so as to obtain a further separation between the additives Adl and Ad2 and to have a first flow of phase 11 whose content of additives Adl is negligible or at least very low, preferably zero.

[0359] At the outlet of the third zone Z3, the division of the first phase A 11 stream, preferably drawn from the bottom of zone Z3, produces the second final additive stream 26 which includes phase A and the second family of additives Ad2, and advantageously without Adl additives and without PVC polymer(s), or possibly in the form of low levels or traces (preferably less than 5% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight of PVC polymer(s), and preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight of additives of the first family Adl, relative to the total weight of the stream considered).The first fraction 12, having the same composition as the second additive stream 26, is mixed with the crude polymer solution 1 (or the clarified polymer solution) to form the feed sent to the first (extraction) zone Zl.

[0360] Preferably, the solvent / feed mass ratio in the third zone Z3 (i.e. extraction liquid 46 / second phase flow A 10) is between 0.1 and 10, preferably between 0.2 and 8, and more preferably between 0.2 and 5.

[0361] Preferably, the number of theoretical floors in the third zone Z3 is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0362] Preferably, the initial phase A 8 feed flow rate at the head of the second zone C is greater than 4 times the crude polymer solution feed flow rate 1.

[0363] Preferably, the feed rate of extraction liquid 46, i.e. phase B, at the bottom of the third zone Z3 is greater than 3 times the feed rate of crude polymer solution 1.

[0364] Preferably, the feed rate of extraction liquid 45, i.e. phase B, at the bottom of the first zone Zl is greater than 7 times the feed rate of crude polymer solution 1.

[0365] Preferably, the drawdown flow rate of the stream 26 at the bottom of the third zone Z3 is greater than 0.13 times the feed flow rate of extraction liquid 45, i.e. phase B, at the bottom of the first zone Z1, less the feed flow rate of initial phase A 8 at the top of the second zone C and less the feed flow rate of crude polymer solution 1 (or clarified polymer solution).

[0366] Figure 7 illustrates a sixth possible embodiment of the invention, according to which step b) is carried out in four coupled zones, formed by two extraction zones Z1 and Z4 and two counter-extraction zones Cl and C2. In the two extraction zones, a flux 47 essentially consisting of phase B is introduced to extract the families of additives contained in phase A from the fluxes introduced into said zones.

[0367] According to this sixth implementation, step b) of liquid-liquid extraction comprises: b.10) a liquid-liquid extraction substep in a first extraction zone Zl of a feed formed by a mixture of the crude polymer solution 1 (or clarified polymer solution) with a first intermediate phase A 15 stream, in contact with a 47 stream of extraction liquid (i.e. phase B), to obtain the purified polymer solution 3 (“A+P”) and a first intermediate phase B 16 stream comprising said at least two families of additives Adl and Ad2; b.11) a liquid-liquid extraction substep of said first intermediate phase B 16 stream in contact with an initial phase A 8 stream in a first counter-extraction zone Cl to counter-extract the PVC polymer(s) of said first intermediate phase B 16 stream, and thus minimize the associated losses in the process, and form a second intermediate phase B 17 stream and the first phase A 15 stream; b.12) a liquid-liquid extraction substep of the second intermediate phase B 17 stream mixed with a third intermediate phase B 18 stream in a second counter-extraction zone C2, in contact with phase A (stream 8'), to counter-extract the PVC polymer(s) of said third intermediate phase B 18 stream and to separate the additive families between phases A and B, e.g. the Ad2 additive family, for example OPFRs, passing into phase A ("counter-extraction" of the Ad2 additive family which passes from phase B to phase A), to form a first final additive stream 27 ("B+Adl") comprising a first Adl additive family, e.g. phthalates, and a second intermediate phase A 19 stream comprising a second Ad2 additive family, e.g. OPFRs; b.13) a liquid-liquid extraction substep of the second intermediate phase A 19 stream in a second extraction zone Z4 in contact with extraction liquid (stream 48), to form said third intermediate phase B 18 stream sent to substep b.12) and a second final additive stream 28 (“A+Ad2”) comprising the second family of additives Ad2 and phase A.

[0368] A portion 29 of said final second additive stream 28, comprising phase A and the second family of additives Ad2, can be sent to the first counter-extraction zone Cl to be mixed with the initial phase A stream 8 introduced into zone Cl.

[0369] According to a variant of this sixth implementation, the second intermediate phase B stream, typically exiting at the top of the first counter-extraction zone C1, is concentrated in a zone S before being sent to the bottom of the counter-extraction zone C2. This concentration can be achieved by any type of separation operation, including evaporation or distillation. Phase B is then recovered as a stream 20, which can then be injected mixed with the phase B stream 47 at the bottom of the first extraction zone Z1 (illustrated by a dashed stream in Figure 7) or the second extraction zone Z4 (not shown). This variant has the advantage of reducing the flow rates of the streams sent to and treated in zones Z4 and C2, as well as the size of the equipment used in these zones.

[0370] This sixth implementation allows the PVC polymer(s) to be separated from at least the two families of additives, e.g. phthalates and OPFRs, but also to have two distinct streams of final additives (e.g. phthalates on one side and OPFRs on the other) in order to valorize these additives separately, as well as to offer an even more advanced separation than in the implementations presented previously, and to limit the losses of PVC polymer(s) which could be very weakly dissolved in phase B.

[0371] The liquid-liquid extraction device according to this implementation may also include means for sending the second intermediate phase B 17 outgoing, preferably upstream, from zone Cl to a concentration system, for example to an evaporation or distillation system of said flow, as well as means for recycling fractions of flow withdrawn from a zone of the liquid-liquid extraction device, such as flow 29 or flow 20, for example a set of conduits, valves, pumps etc., to another zone of the device.

[0372] In the first extraction zone Zl, the additives of the two families Adl and Ad2 are extracted from the extraction liquid, i.e., phase B (see solid and dashed gray arrows). The extract formed, i.e., the first intermediate stream 16, therefore comprises phase B and at least the two families of additives Adl and Ad2. The raffinate formed in the first extraction zone Zl, i.e., the purified polymer solution 3, comprises phase A and the PVC polymer(s), advantageously without additives or possibly containing trace amounts of additives from at least the two families Adl and Ad2, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight, or even less than 0.01% by weight of said additives (relative to the total weight of the stream considered).

[0373] The first extraction zone Zl and its operation are configured so as to "purify" phase A of the additives initially present.

[0374] Preferably, the solvent / feed mass ratio in the first extraction zone Zl of extraction (i.e. extraction liquid 47 / feed (crude polymer solution 1 (or clarified polymer solution) + flux 15) is between 1 and 10, preferably between 1 and 8, and more preferably between 1 and 5.

[0375] Preferably, the number of theoretical floors in the first extraction zone Zl is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0376] Preferably, the flow rate of crude polymer solution 1 (or clarified polymer solution) in the first extraction zone Zl is between 0.1 t / h and 380 t / h, preferably between 0.3 t / h and 125 t / h, more preferably between 0.6 t / h and 20 t / h.

[0377] In the first counter-extraction zone Cl, any additives present due to the recycling of a portion of streams 29 and / or 20 in zones Cl and Z1, respectively, can be extracted in phase B. The PVC polymer(s) present in phase B of the first intermediate stream of phase B 16, preferably introduced at the bottom of zone C, are counter-extracted in phase A. The first counter-extraction zone Cl and its operation are indeed configured to counter-extract the PVC polymer(s) and minimize associated losses, as well as to extract any additives in phase B. The extract formed, i.e.the second intermediate flux of phase B 17, therefore comprises phase B and the two families of additives Adl and Ad2, advantageously without PVC polymer(s) or present in very low levels or even in trace amounts, preferably less than 5% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.1% by weight of PVC polymer(s) (relative to the total weight of the flux considered).

[0378] Preferably, the solvent / feed mass ratio in the first counter-extraction zone Cl (i.e. flux 16 / initial flux of phase A 8) is greater than or equal to 0.8, preferably greater than or equal to 1.2, and more preferably greater than or equal to 7, and preferably less than or equal to 100.

[0379] Preferably, the number of theoretical floors in the first counter-extraction zone Cl is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0380] In the second counter-extraction zone C2, the additives of the second family Ad2 are counter-extracted in phase A, and the additives of the first family Adl are extracted in phase B, to form the first final additive stream 27 comprising phase B and the first family of additives Adl, and the second intermediate phase A stream 19. Advantageously, the first final additive stream 27 does not include additives of the second family Ad2 or includes them in trace amounts (less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight), and does not include PVC polymer(s) or includes them in very low levels or even in trace amounts (less than 5% by weight, preferably less than 1% by weight, more preferably less than 0.5% or 0.1% by weight).

[0381] The second counter-extraction zone C2 and its operation are indeed configured so as to separate the two families of additives between phases A and B, and possibly counter-extract the PVC polymer(s) and minimize the associated losses.

[0382] Preferably, the solvent / load mass ratio in the second counter-extraction zone C2 (i.e. flux 18 + flux 17 / initial flux of phase A 8') is between 0.1 and 10, preferably between 0.2 and 8, and more preferably between 0.2 and 5.

[0383] Preferably, the number of theoretical floors in the second counter-extraction zone C2 is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0384] In the second extraction zone Z4, the additives of the first family Adl still present in the second intermediate flow of phase A 19 are extracted into the extraction liquid, i.e. phase B. The extract formed, i.e. the third intermediate flow of phase B 18, therefore comprises phase B and additives of the first family Adl. The raffinate formed in the second extraction zone Z4, i.e. the second final additive stream 28, comprises from phase A, and the additives of the second family Ad2, advantageously without additives of the first family Adl or in trace amounts (less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight), and without PVC polymer(s) or present in very low levels or even in trace amounts (less than 5% by weight, preferably less than 1% by weight, more preferably less than 0.5% or 0.1% by weight).The second extraction zone Z4 and its operation are configured so as to separate the additives between the two phases A and B and purify the second final additive stream 28 containing the second family of additives.

[0385] Preferably, the solvent / feed mass ratio in the second extraction zone Z4 (i.e. extraction liquid 48 / flow 19) is between 0.1 and 10, preferably between 0.2 and 8, and more preferably between 0.2 and 5.

[0386] Preferably, the number of theoretical floors in the second extraction zone Z4 is between 1 and 15, preferably between 1 and 10, and more preferably between 2 and 10.

[0387] According to this sixth implementation, it is possible to use a single piece of equipment to carry out sub-steps b.10) and b.11) and / or a single piece of equipment to carry out sub-steps b.12) and b.13), i.e. the first extraction zones Z1 and counter-extraction Cl can be part of a single liquid-liquid extraction piece of equipment, and likewise for the second extraction zones Z4 and counter-extraction C2.

[0388] Step c) Polymer-solvent separation

[0389] According to the invention, the process includes a step c) of polymer-solvent separation, to separate the purified polymer solution and obtain a stream of purified PVC polymer(s) and at least a solvent fraction comprising phase A.

[0390] Step c) of polymer-solvent separation advantageously employs at least one solvent recovery section and preferably between one and five solvent recovery section(s).

[0391] Advantageously, step c) is fed by the purified polymer solution obtained at the end of step b) or possibly a final purified polymer solution from an additional purification step located downstream of step b).

[0392] Step c) of polymer-solvent separation thus aims first to separate at least in part, preferably predominantly, the solvent(s) of phase A, and possibly the solvent(s) of phase B (in traces), contained in the polymer solution which feeds step c), i.e. the purified polymer solution 3 or possibly a final purified polymer solution from an additional purification step, so as to recover the PVC polymer(s), freed at least in part, preferably predominantly and preferably totally, of said solvents. By predominantly, we must understand the removal of at least 50% by weight, preferably at least 70% by weight, preferably at least 90% by weight, more preferably at least 95% by weight, very preferably at least 99% by weight, or even at least 99.9% by weight, of the solvent(s) (relative to the weight of the solvent(s) contained in the purified polymer solution that feeds step c).

[0393] Any solvent / polymer separation method known to those skilled in the art may be used, including any method that induces a phase change in the polymer(s) and / or solvent(s). The solvent(s) may be separated from the PVC polymer fraction, for example, by precipitation or crystallization of the PVC polymers, solvent evaporation, flash devolatilization, atomization (high-pressure nozzle, rotary atomizer, bi-fluid nozzle, ultrasonic atomizer), stripping, demixing, extrusion, density difference, and in particular decantation or centrifugation, etc.

[0394] The purified PVC polymer stream thus obtained can correspond to a concentrated polymer solution or to at least one purified PVC resin in solid form. Preferably, step c) of polymer-solvent separation further includes a conditioning section for conditioning at least one purified PVC resin in solid form, and more particularly in the form of powder, beads, or granules.

[0395] Step c) of polymer-solvent separation also aims to recover at least part, preferably the majority, and preferably all, of the solvent(s) contained in the purified polymer solution that feeds step c). Step c) of polymer-solvent separation also aims, if necessary, to purify and recycle the recovered solvent fraction, particularly upstream of step a) of dissolution. "The majority" should be understood to mean at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight, and even more preferably at least 95% by weight relative to the weight of the solvent(s) contained in the purified polymer solution that feeds step c).

[0396] Advantageously, step c) of polymer-solvent separation employs at least one solvent recovery section, the latter preferably comprising equipment operated at different temperatures and pressures, in order to obtain at least one solvent fraction and the purified polymer fraction.

[0397] Thus, the process according to the invention makes it possible to efficiently and continuously recover PVC polymers from a plastic feedstock, with high productivity and a limited number of operations. Very advantageously, the process according to the invention makes it possible to obtain a stream of PVC polymer(s) exhibiting high purity, preferably greater than or equal to 98%, preferably greater than or equal to 99%, and preferably greater than or equal to 99.9% (by weight of PVC polymer(s) relative to the total weight of the recovered purified stream), from any type of PVC-based plastic feedstock.Another advantage of the process according to the invention lies in the fact that efficient separation of the additives present in the plastic filler is possible with a single solvent system, and even advantageous separation of the additives themselves according to their chemical family, allowing for their subsequent recovery, while also enabling reasonable solvent consumption and lower energy consumption than that required for more conventional, so-called thermal separations, such as crystallization. The process according to the invention thus makes it possible to obtain a purified PVC polymer stream, in particular free of any additive currently regulated and / or prohibited by REACH, which, due to its presence, prevents the material recovery of said PVC polymer stream.More particularly, the process according to the invention makes it possible to obtain a purified PVC polymer stream free of at least some, preferably all, of the additives, and any impurities, present in the plastic filler, and free, at least in part or even in full, of solvents, in particular the solvents of the biphasic solvent system used.Thus, the process according to the invention advantageously makes it possible to obtain a purified PVC polymer stream comprising a solvent content of less than or equal to 10% by weight, preferably less than or equal to 5% by weight, preferably less than or equal to 1.0% by weight, and even more preferably less than or equal to 0.1% by weight, and very advantageously a content of additives and any impurities of less than or equal to 2% by weight, preferably less than or equal to 1.0% by weight, even more preferably less than or equal to 0.5% by weight, or even less than or equal to 0.1% by weight (percentages of additives and any impurities given relative to the total weight of the sum of the PVC polymer(s) and the residual additives and any impurities in the purified PVC polymer stream). In particular, the purified PVC polymer stream obtained very advantageously has the following contents:

[0398] - less than 0.1% by weight of phthalates subject to authorization by the REACH regulation in Europe (Annex XIV of Regulation (EC) No 1907 / 2006 of the European Parliament and of the Council of 18 December 2006), in particular strictly less than 0.1% by weight of phthalates selected from the list consisting of the following phthalates: dibutyl phthalate (DBP), dioctyl or diethylhexyl phthalate (DOP or DEHP), benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, alone or in mixtures,

[0399] - less than 0.1% by weight of the element lead, in particular said lead contained in metallic stabilizer type additives assessed under the REACH regulation and subject to restrictions (Annex XV) detailed and adopted between December 2017 and March 2018 by the ECHA Risk Assessment Committee (RAC) and Socio-Economic Analysis Committee (SEAC),

[0400] - less than 0.1% by weight, and preferably less than 0.01% by weight, of the element cadmium, in particular said cadmium contained in metallic stabilizer type additives prohibited by the REACH regulation according to the amendment of Annex XVII (Regulation 494 / 2011 of 20 May 2011).

[0401] Optional step d) of additive-solvent separation

[0402] The process according to the invention may include a step d) of separating the additives from the solvent(s) in the final additive stream(s) comprising said at least two families of additives.

[0403] Any solvent / organic (macro)molecule separation method known to those skilled in the art can be implemented and applied to at least one compound or family of compounds constituting said additives, for example, by L / L extraction, adsorption, crystallization, precipitation, evaporation, distillation, demixing followed by decantation / centrifugation, etc. The solvent / organic (macro)molecule separation method(s) are chosen by those skilled in the art based on the valorization required for said additives by the applicant, itself a function of the PVC-based plastic feedstock to be processed. The final additive stream(s) containing phase B can be sent to this step (d) and allow for the recovery of phase B for reuse as an extraction liquid in the process at the liquid-liquid extraction step (b).

[0404] Examples

[0405] The following examples illustrate the invention, in particular specific implementations of the invention, without limiting its scope.

[0406] Examples 1-3 are derived from numerical simulations. Example 4 is the result of laboratory experiments using a CPC device.

[0407] In the various examples below, the two-phase solvent system used in the process has the composition given in Table 1 below (contents in percentage weight relative to the total weight of a given phase).

[0408] Table 1

[0409] Example 1

[0410] This example implements a liquid-liquid extraction device with a single zone, similar to that shown in Figure 2.

[0411] The PVC-based plastic filler (filler A), comprising a PVC polymer resin with a molar mass MW=120,000 g / mol (35% by weight of PVC polymer relative to the total weight of the plastic filler), has a high content of additives, in particular 65% by weight of two families of additives (relative to the total weight of the plastic filler): the first family Adl composed of 60% phthalates (distribution 30% by weight of diisodecyl phthalate, DIDP (“PI”), 30% by weight of dibutyl phthalate, DBP (“P2”)) and the second family Ad2 composed of 5% organophosphates (2% of tri-o-cresyl phosphate “0PFR1” and 3% of triphenyl phosphate “0PFR2”).

[0412] The plastic filler is previously solubilized in a dissolving liquid of identical composition to that of phase A of the biphasic solvent system, according to a mass ratio of plastic filler / dissolving liquid equal to 0.12 (weight quantity of PVC polymer(s) present in the plastic filler relative to the weight of the dissolving liquid equal to 4%).

[0413] The crude polymer solution 1 thus formed (heavy phase) is sent to a liquid-liquid extraction step: the crude polymer solution 1 is injected into a liquid-liquid extraction zone with an extraction liquid consisting of phase B of the biphasic solvent system (light phase), injected at the bottom of the zone so as to operate in counter-current flow. Phase B is dispersed.

[0414] The crude polymer solution flow rate is 10,000 kg / h. The number of theoretical stages (NET) in the liquid-liquid extraction zone is 10. The solvent mass ratio (extraction liquid 40 consisting of phase B) / feed (crude polymer solution 1) is 8.6. After the liquid-liquid extraction step, a purified polymer solution is recovered and sent to a polymer / solvent separation step by solvent evaporation.

[0415] The contents of additives in the purified polymer stream, after the polymer-solvent separation step, are given in the following Table 2.

[0416] Table 2

[0417] By proceeding in this way, all the additives initially present in the plastic feed are extracted so as to achieve a residual content in the purified polymer stream of less than 0.1% by weight (relative to the total weight of purified polymer stream).

[0418] Example 2

[0419] This example implements a liquid-liquid extraction device with a single zone, similar to that shown in Figure 2.

[0420] The PVC-based plastic filler differs from that in Example 1: it contains the same PVC polymer resin with a molar mass MW = 120,000 g / mol, but with a lower additive content. In this Example 2, the PVC-based plastic filler (filler B) contains 10 wt% diisodecyl phthalate, DIDP (“PI”), and 1 wt% organophosphate compounds: tri-o-cresyl phosphate (“0PFR1”).

[0421] The plastic filler dissolution step is similar to that carried out in example 1.

[0422] The crude polymer solution flow rate is 2,000 kg / h. The theoretical number of stages (NET) in the liquid-liquid extraction zone is 6. The solvent (extraction liquid 40, consisting of phase B) / feed (crude polymer solution 1) mass ratio is 5, resulting in a solvent (extraction liquid 40) flow rate of 10,000 kg / h. After the liquid-liquid extraction step, a purified polymer solution is obtained and sent to a polymer / solvent separation step by solvent evaporation, similar to that performed in Example 1.

[0423] The additive contents in the purified polymer stream, after the polymer-solvent separation step, are given in Table 3 below. Table 3

[0424] By proceeding in this way, all additives initially present in the plastic feed are extracted so as to achieve a residual content in the purified polymer stream of less than 0.05% by weight (relative to the total weight of purified polymer stream).

[0425] Example 3

[0426] This example implements a liquid-liquid extraction device with two coupled extraction zones, similar to that shown in Figure 3.

[0427] The PVC-based plastic filler is filler A in example 1 (high additive content).

[0428] The plastic filler dissolution step is similar to that carried out in example 1.

[0429] The crude polymer solution 1 thus formed (heavy phase) is sent to a liquid-liquid extraction step: the crude polymer solution 1 is injected at the top of a first liquid-liquid extraction zone ZI and brought into contact with a first flow of extraction liquid 41, consisting of phase B of the biphasic solvent system (light phase), injected at the bottom of zone ZI, so as to operate in counter-current flow. Phase B is dispersed.

[0430] After passing through zone Zl, at the top of zone Zl we recover a first final additive stream 21 consisting mainly of phase B and additives of the first family Adl, and at the bottom of zone Zl an intermediate polymer solution 5 containing mainly PVC polymer and additives of the second family Ad2 in phase A.

[0431] The intermediate polymer solution 5 exiting at the bottom of zone Z1 is injected at the top of a second zone Z2 where it is brought into contact with a second extraction liquid stream 42, i.e., phase B, injected at the bottom of zone Z2. A purified polymer solution containing mainly PVC in phase A is collected at the outlet of zone Z2, at a withdrawal point at the bottom of zone Z2, and a second final additive stream 22 containing mainly the additives of the second family Ad2 and of phase B is collected at a withdrawal point at the top of zone.

[0432] For zone Zl:

[0433] - The flow rate of crude polymer solution 1 at the inlet is 10,000 kg / h,

[0434] - The number of theoretical stages (NET) is between 5 and 10 according to the specifications referred to on the final additive flows,

[0435] - The mass ratio of solvent (extraction liquid 41 consisting of phase B) to feedstock (crude polymer solution 1) is 2. For zone Z2:

[0436] - the flow rate of intermediate polymer solution 5 at the inlet is between 9000 and 10000 kg / h,

[0437] - The number of theoretical floors (NET) is 9,

[0438] - the mass ratio of solvent (extraction liquid 42 consisting of phase B) / load (intermediate polymer solution 5) is 8.

[0439] The additive contents in the final additive streams 21 and 22 drawn from zones ZI and Z2 respectively are given in Tables 4 and 5 below.

[0440] Table 4

[0441] Table 5 After the liquid-liquid extraction step, the purified polymer solution 3 is recovered from the outlet of zone Z2, which is sent to a polymer / solvent separation step by solvent evaporation.

[0442] The contents of additives in the purified polymer stream, after the polymer-solvent separation step, are given in the following Table 6.

[0443] Table 6 Table 4 shows that the implementation conditions allow us to obtain a first final additive flow 21 enriched in additives of the Adl family, regardless of the NET considered between 5 and 10.

[0444] Table 5 shows that the second final additive stream 22 exiting zone Z2 is mainly composed of additives from the second family Ad2. Depending on the purity specifications for this stream, the NET of zone ZI can be adjusted to achieve very low levels of additives from the Adl family in this second final additive stream (< 15 ppm wt).

[0445] Table 6 shows that the content of additives in the purified polymer stream obtained from the purified polymer solution 3 exiting zone Z2 and freed from solvents in the polymer / solvent separation step is less than 0.4% wt for organophosphates (Ad2 family) and less than 0.1% ppm wt for phthalates (Adl family).

[0446] By proceeding in this way, all additives initially present in the plastic feedstock are extracted, resulting in a residual content in the purified polymer stream well below 0.1% by weight for phthalate-type additives (relative to the total weight of the purified polymer stream). Simultaneously, the two families of additives, Adl and Ad2, were selectively separated.

[0447] Example 4

[0448] This example is the result of experiments carried out in the laboratory.

[0449] The plastic material to be processed is virgin PVC plastic in the form of 2 to 3 mm granules, the composition of which, as a percentage by weight (relative to the total weight of the material), is as follows:

[0450] - 55.31% PVC resin (polymer) with a K-value of 75 (K-value expressing the average molecular weight of PVC resin), corresponding to a molar mass MW=120,000 g / mol,

[0451] - 24.34% diisodecyl phthalate (DIDP),

[0452] - 3.32% epoxidized soybean oil,

[0453] - 0.11% polyethylene wax AC 629,

[0454] - 16.59% calcium carbonate,

[0455] - 0.11% zinc stearate,

[0456] - 0.17% calcium stearate,

[0457] - 0.06% blue pigment.

[0458] The plastic filler is first dissolved in a dissolving liquid formed by mixing solvents of the same composition as phase A of the two-phase solvent system used in the process (see Table 1) at 70°C, at atmospheric pressure, to form a homogeneous crude polymer solution comprising 80% by weight of said dissolving liquid and 20% by weight of plastic filler. In particular, the dissolving liquid has a composition identical to that of phase A of the two-phase solvent system (see Table 1).

[0459] The plastic filler / dissolving liquid mixture is placed in an oven for 5 hours at 70°C. The resulting solution is then centrifuged for 10 minutes at 5300 rpm to remove insoluble components (in this case, calcium carbonate, zinc stearate, calcium stearate, and blue pigment). A clarified polymer solution, suitable for use in a CPC system, is obtained after centrifugation. This solution is then introduced into the cells of a CPC column. The CPC system consists of an SCPC100 Centrifugal Partition Chromatograph coupled to Spot Prep II from Armen Instruments, France (Gilson Purification, USA), which includes the column, pumps, and collector. The column used is 131 mL. The cells are filled with a biphasic system of immiscible phase A and phase B in equilibrium. Phase A is maintained in the cells of the CPC device by centrifugal force, the rotor rotating at 2000 rpm. Phase B (seecomposition in table 1), corresponding to the mobile phase, passes through phase A, called stationary, with a flow rate of 7ml / min.

[0460] In particular, the following procedure is used for splitting within the column:

[0461] The column is filled with stationary phase (phase A) and rotated at 500 rpm in upward mode at a flow rate of 30 ml / min, then the rotation is set at 2000 rpm. Mobile phase (phase B) is introduced at 7 ml / min to equilibrate the chromatographic system, with a stationary phase retention of 50% and a pressure drop of 0.53 MPa. No leakage is observed.

[0462] The injection solution is then introduced into the column via a 5 mL injection loop, subsequently pushed by the mobile phase at 7 mL / min in upward flow mode. Elution is continued for 2 hours. Following elution, extrusion is performed with a fresh introduction of the stationary phase at 30 mL / min for 10 minutes. The effluent is fractionated using an automatic fraction collector.

[0463] DIDP has a partition coefficient between phase A and phase B of 3.03. PVC resin does not partition between the two phases; it remains in phase A.

[0464] After injection of the clarified polymer solution into the CPC device and after a cell equilibration phase, the DIDP passes through the different cells, carried by its affinity with the mobile phase and exits the device with the mobile phase.

[0465] To recover the stationary phase, it is pushed through by adding mobile phase and reversing the injection direction. The PVC resin solubilized in phase A is thus recovered.

[0466] The resin is recovered by reprecipitation. 250 mL of methanol is added to phase A containing the polymer. The mixture is then filtered using a Buchner funnel to recover the powder corresponding to the pure polymer. The powder is then dried to remove the solvent.

[0467] The additives are analyzed by liquid chromatography coupled to high-resolution mass spectrometry LC-HRMS: Agilent 1290 coupled to timsTOF (TIMS for Trapped Ion Mobility Spectrometry, which is the spectrometry of the mobility of trapped ions, and TOF for Time of flight, which is the time of flight, corresponding to a type of analyzer in mass spectrometry), Bruker Daltonics, Germany using an Apollo II source, Bruker Daltonics, Germany.

[0468] The additives found in the extrusion fractions (mobile phase) are:

[0469] - The plasticizer di-isodecyl phthalate (DIDP), - The co-stabilizer epoxidized soybean oil,

[0470] - Polyethylene wax lubricant.

[0471] The purified PVC polymer is analyzed by FTIR on a Nicolet™ iS50 FTIR Spectrometer (ThermoFisher Scientific) and by NMR analysis 1 H and 13 C. The polymer is recovered in 100% pure form. The polymer is found to be pure, without the presence of any other species, by NMR and FTIR analysis.

Claims

Demands 1. A process for recovering a purified PVC polymer stream(s) from a PVC-based plastic feed comprising one or more PVC polymers and at least two families of additives employing a two-phase solvent system comprising two immiscible liquid phases A and B, said process comprising: a) a dissolution step comprising contacting the PVC-based plastic feed with a dissolution liquid consisting of the liquid phase A of the two-phase solvent system, to obtain at least one crude polymer solution (1); b) a liquid-liquid extraction step, in at least one zone, of the crude polymer solution (1), in the presence of a single extraction liquid (4, 41, 42, 43, 44, 45, 46, 47, 48) consisting of the liquid phase B of the two-phase solvent system to obtain a purified polymer solution (3) and at least one final additive stream (2, 21, 22, 23, 24, 25, 26, 11, 28) comprising said at least two families of additives;c) a polymer-solvent separation step, to separate the purified polymer solution into a stream of purified PVC polymer(s) and at least a solvent fraction comprising the liquid phase A.; 2. A process according to claim 1, wherein step b) is carried out in a single zone (Z0) to form the purified polymer solution and a single final additive stream (2) comprising said at least two families of additives.

3. A process according to claim 1, wherein step b) is carried out in at least two zones to form the purified polymer solution (3) and a single final additive stream (2) comprising said at least two families of additives or at least two final additive streams each containing one of said two families of additives (21, 22, 23, 24, 25, 26, 11, 28).

4. A process according to claim 3, wherein the liquid-liquid extraction step b) is carried out in two zones (Z1, Z2) and comprises: b) a liquid-liquid extraction substep of the crude polymer solution in the presence of the extraction liquid (41) in a first extraction zone (Z1) to obtain an intermediate polymer solution (5) and a first final additive stream (21) comprising a first family of additives (Ad1); b.2) a liquid-liquid extraction substep of said intermediate polymer solution (5) in the presence of the extraction liquid (42) in a second extraction zone (Z2) fluidically coupled to said first extraction zone (Z1), to obtain the purified polymer solution (3) and a second final additive stream (22) comprising a second family of additives (Ad2); preferably the mass ratio of the extraction liquid (42) to the intermediate polymer solution (5) in the second extraction zone (Z2) being greater than or equal to the mass ratio of the extraction liquid (41) to the crude polymer solution (1) in the first extraction zone (Z1).

5. A process according to claim 3, wherein the liquid-liquid extraction step b) is carried out in two zones (Z, C) and comprises: b.3) a liquid-liquid extraction substep in an extraction zone (Z) of a feed formed by a mixture of the crude polymer solution (1) with a first phase A stream (6), in contact with the extraction liquid (43), to obtain the purified polymer solution (3) and an intermediate extract (7) comprising said at least two families of additives; b.4) a liquid-liquid extraction substep of said intermediate extract (7) in a counter-extraction zone (C) to counter-extract the PVC polymer(s) of said intermediate extract (7) in contact with an initial phase A stream (8) and obtain the final additive stream (2) comprising said at least two families of additives and said first phase A stream (6) mixed with the crude polymer solution (1) to form the feed sent to step b.3), preferably the liquid extraction mass ratio (43) / sum of crude polymer solution and first phase A flux (6) in the extraction zone (Z) being less than the mass ratio of intermediate extract (7) to initial phase A flux (8) in the counter-extraction zone (C).

6. A process according to claim 3, wherein the liquid-liquid extraction step b) is carried out in at least three zones (Z1, Z3, C) and comprises: b.7) a liquid-liquid extraction substep in a first zone (Z1) of a feed formed by mixing the crude polymer solution (1) with a first fraction (12) of a first phase A stream (11), in contact with extraction liquid (45), to obtain the purified polymer solution (3) and a first intermediate stream (13) comprising said at least two families of additives; b.8) a liquid-liquid extraction substep of said first intermediate stream (13) in contact with an initial phase A stream (8) in a second zone (C) to counter-extract the PVC polymer(s) of said first intermediate stream (13) and separate the two families of additives between phases A and B, and obtain a final first additive stream (25) comprising a first family of additives and a second phase A stream (10) comprising a second family of additives; b.9) a liquid-liquid extraction substep of the second phase A stream (10) in a third zone (Z3) in contact with extraction liquid (46), to form said first phase A stream (11) and a second intermediate stream (14) sent to the second zone (C) in step b.8);. and we carry out a withdrawal of the first phase A flux (11) exiting the third zone (Z3) to form the first fraction (12) of the first phase A flux (11) and a second complementary fraction of the first phase A flux (11) constituting a second final additive flux (26) comprising a second family of additives.

7. A method according to any one of the preceding claims, wherein phase B has a lower density than the density of phase A and flows upwards and counter-currently to phase A in said at least one zone in step b).

8. A method according to any one of the preceding claims, wherein said at least one zone in step b) of liquid-liquid extraction comprises at least one liquid-liquid extraction device selected from: - gravity columns equipped with perforated trays; - gravity columns equipped with bulk or structured packing; - gravity columns equipped with trays and bulk or structured packing; - agitated columns; - pulsed columns; - cascade mixer-decanters; - centrifugal partition chromatography devices; and - centrifugal extractors.

9. A process according to any one of the preceding claims, comprising: a') a step of separating the insolubles from the crude polymer solution obtained at the end of step a) before sending it to step b).

10. A method according to any one of the preceding claims, wherein said solvent system is characterized in that: - phase A and phase B each comprise an organic solvent or a mixture of organic solvents chosen from the same list consisting of ketones, amides, azines, esters, ethers, halogenated solvents, hydrocarbons, sulfide solvents, and dihydrolevoglucosenone; - the organic solvent or mixture of organic solvents of said phase A is capable of solubilizing the PVC polymer(s) of the PVC-based plastic filler; - the two-phase solvent system is capable of solubilizing at least two families of additives; - the partition coefficient of the PVC polymer(s) in the two-phase solvent system, defined as the ratio of the mass concentrations of the PVC polymer(s) dissolved in phase B and in phase A, tends towards zero, and the partition coefficient of said families of additives in the two-phase solvent system, defined as the ratio of the mass concentrations of said families of additives dissolved in phase B and in phase A, is greater than or equal to 0.

05.

11. A method according to claim 10, wherein the organic solvent(s) for each of phases A and B of said two-phase solvent system are selected from the list consisting of: - the following compounds from the ketone family: methyl ethyl ketone, diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone, cyclopentanone and cyclohexanone; - the following compounds from the amide family: N,N-diethylformamide, 2-pyrrolidone and N-methyl-2-pyrrolidone; - the following compounds from the azine family: pyridine, 4-aminopyridine, 2-aminopyridine, and 4-vinylpyridine; - the following compounds from the ester family: methyl acetate, ethyl acetate, methyl propionate, n-butyl propionate, γ-butyrolcatone and γ-valerolactone; - the following compounds from the ether family: methoxycyclopentane, diisopropyl ether, tetrahydrofuran and methyl tetrahydrofuran; - the following compounds from the chlorinated solvent family: dichloromethane and trichloromethane - the following compounds from the hydrocarbon family: xylene, cyclohexane, toluene, isohexane and n-heptane; - the following compound from the family of sulfide solvents: dimethyl sulfoxide; - dihydrolevoglucosenone.

12. A process according to claim 11, wherein phase A of said two-phase solvent system comprises a first mixture of at least two of the following organic solvents: - a predominantly sulfurous solvent, - a first minor solvent selected from ketones and cyclic esters, preferably selected from methyl ethyl ketone, diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone, cyclopentanone, γ-butyrolcatone, and γ-valerolactone, and phase B comprises a second mixture of at least the following two organic solvents: - a major solvent chosen from hydrocarbons, preferably from xylene, isohexane and n-heptane, - a first minor solvent chosen from among the ketones and cyclic esters, preferably chosen from methylethyl ketone, diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, methylisobutyl ketone, cyclopentanone, y-butyrolcatone, and y-valerolactone.

13. A process according to claim 12, wherein the first mixture of phase A of said two-phase solvent system comprises at least three of the following organic solvents: - the major solvent dimethyl sulfoxide, at a content of at least 50% by weight, - the first minor solvent chosen from among ketones and cyclic esters, preferably from diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, γ-butyrolcatone and γ-valerolactone, and - a second minor solvent chosen from hydrocarbons, preferably from xylene, cyclohexane, isohexane and n-heptane, and the second mixture of phase B of said two-phase solvent system comprises the following three organic solvents: - the major solvent, with a content of at least 50% by weight, chosen from hydrocarbons, preferably from xylene, cyclohexane, isohexane and n-heptane, - the first minor solvent chosen from among ketones and cyclic esters, preferably from diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, γ-butyrolcatone, and γ-valerolactone, and - a second minor solvent chosen from among the sulfide solvents, preferably dimethyl sulfoxide.

14. A process according to claim 13, wherein the first mixture of phase A of said two-phase solvent system comprises the following three organic solvents: - the major solvent dimethyl sulfoxide, at a content of at least 50% by weight, preferably at a content between 50% and 70% by weight, preferably between 55% and 65% by weight; - the first minor solvent diethyl ketone, preferably at a content between 20% and 40% by weight, preferably between 25% and 35% by weight, and - the second minor solvent n-heptane, preferably in a content less than or equal to 15% by weight, preferably between 5% and 15% by weight, preferably between 5% and 10% by weight, and the second mixture of phase B of said two-phase solvent system comprises the following three organic solvents: - the major solvent n-heptane, at a content of at least 50% by weight, and preferably at a content between 50% and 70% by weight of n-heptane, preferably between 55% and 65% by weight; - the first minor solvent diethyl ketone, preferably at a content between 20% and 40% by weight, preferably between 25% and 35% by weight, and - the second minor solvent dimethyl sulfoxide, preferably at a content less than or equal to 15% by weight, preferably between 5% and 15% by weight, preferably between 5% and 10% by weight.

15. A method according to any one of the preceding claims, wherein said at least two families of PVC-based plastic filler additives are included in the list consisting of: - the family of organotins used as stabilizing additives; - metallic compounds used as stabilizing additives containing lead or cadmium, preferably lead and cadmium stearates; - the family of ortho-phthalates used as plasticizing additives, preferably dioctyl phthalate DOP, bis(2-ethylhexyl) phthalate DEHP, dibutyl phthalate DBP, benzyl butyl phthalate BBP, di-isobutyl phthalate DIBP, di-pentyl phthalate DPP; - the family of terephthalates used as plasticizing additives; - the family of trimellitates used as plasticizing additives; - the family of benzoates used as plasticizers; - the family of mono, di and triphosphites and their derivatives used as heat stabilizing additives; - the family of phenyl 1,3-diones used as heat-stabilizing additives; - the family of organophosphates used as flame retardant additives.

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