Method for the conversion of phthalates contained in PVC plastic materials by extraction and transesterification

Abstract

The present invention relates to a method for obtaining dialkyl phthalates and recyclable target PVC plastic materials from a PVC feedstock containing at least one phthalate, comprising: a) solid-liquid extraction of said PVC feedstock in particulate form; said particles of PVC feedstock are subjected to a solid-liquid extraction of dialkyl phthalates of the ester, ether, ketal or acetal type, the solid-liquid extraction comprising: n H 2n+1 O) m Z is selected from R, COOR, CO, CR, CNRR', PO, P, SO, SO2, COR or HCO, where R and R' are alkyl or aryl groups; b) contacting the phthalates in the liquid phase with a solvent containing at least one chemical molecule of formula CH(COOC) n H 2n+1 a) converting the phthalate-depleted PVC plastic material into a dialkyl phthalate of 2 by transesterification with said solvent; b) solid-liquid separation between a solid phase and a liquid phase; producing at least one solid stream comprising said phthalate-depleted PVC plastic material to obtain said target PVC plastic material; c) liquid-liquid separation of a liquid phase; producing at least a first liquid effluent comprising said dialkyl phthalate and a second liquid effluent comprising at least said solvent.

Description

[Technical field]

[0001] The present invention relates to the field of recycling of plastics based on polyvinyl chlorides (PVC), in particular to a method for extracting and converting, by transesterification, the plasticizer phthalates present in the composition of PVC. More precisely, the invention relates to a method for recovering dialkyl phthalate (DAP) and reusable target PVC plastics from a PVC feedstock containing at least one phthalate. [Background technology]

[0002] By definition, a plastic is a mixture of a base polymeric material and numerous additives, the assembly of which can be molded or shaped (generally at high temperature and / or under pressure) to obtain a semi-finished product or object. The generally accepted practice is to name said plastic by the name of the polymer from which it is made. Thus, the plastic polyvinyl chloride (PVC) corresponds in fact to a combination of the polymer PVC, hereafter called "PVC resin", and various additives chosen depending on the functionality required of said plastic. Said additives may be organic molecules or macromolecules or alternatively inorganic (nano)particles, and are used depending on the properties they give to the PVC resin: resistance to heat, light or mechanical stress (stabilizers), flexibility (plasticizers), processability (lubricants), coloring (dyes / pigments), etc.

[0003] There are several methods for recycling PVC plastics: "conventional" methods with simple mechanical recycling of plastics, methods involving modification of their composition and even chemical transformation of the compounds that make up the plastic.

[0004] Since the middle of the twentieth century, chemical recycling of PVC plastics has been the subject of numerous studies directed towards dissolving the PVC resin with additives in variable proportions in a first step and then recovering said resin in the presence of all or part of the soluble additives in a second step using various chemical methods (precipitation, evaporation, etc.). For example, patent documents 1 to 3 are each directed towards recycling various PVC-based objects (flexible or rigid pipes, window frames, cables, etc.), in particular fibre-reinforced PVC-based objects (tarpaulins, flooring, etc.), according to a method comprising a first step of dissolving the PVC resin and soluble additives in an organic solvent, followed by a second step of precipitation with water vapour, allowing the recovery of the resin and most of the additives.

[0005] However, it is not always desirable to retain said additives in the PVC thus recovered in order to be recycled. Changes in the regulations concerning them over time are, for example, a determining factor. Thus, certain plasticizers belonging to the phthalate family, which were particularly widely used in the formulation of "flexible" PVC about 40 years ago, have been subject to gradual authorisation under the REACH regulation in Europe and, since the end of 2006, have been gradually removed from the additives permitted for use, aimed at establishing the safety of the production and use of chemicals in European industry. This applies, inter alia, to the following non-exhaustive list of phthalates: dibutyl phthalate (DBP), dioctyl phthalate (DOP) or diethyl hexyl phthalate (DEHP), benzyl butyl phthalate (BBP), diisobutyl phthalate (DIBP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, etc.

[0006] These new regulations are now moving towards a ban on the presence of such compounds in recycled raw materials (RRM). Given the often very long life span (decades) of PVC-based objects, PVC-based objects compounded before the end of 2006 and now at the end of their life span cannot be recycled via regeneration methods that lead to the maintenance of these banned additives, whether they are traditional methods, e.g. mechanical recycling methods or not, e.g. the dissolution / precipitation methods mentioned above.

[0007] Furthermore, the phthalate plasticizers currently used in Europe (REACH compliant phthalates) and in the rest of the world represent high value-added additives, which are not upgraded if they are to be maintained in the PVC recycled feedstock. The reason for this is that they are expensive products, are present in significant proportions (tens of percent) in the initial PVC formulation, and cannot directly impart ad-hoc flexibility properties to the PVC RRM. A significant supply of "fresh" plasticizers is essential for the reusability of recycled PVC materials.

[0008] The extraction of phthalate-type additives from PVC-based objects for removal or upgrading is thus a major challenge for the optimized recyclability of PVC.

[0009] Several methods have been adopted to allow this extraction, including a step of dissolving the PVC resin. For example, both US Pat. No. 5,999,623 and US Pat. No. 5,299,633 propose a first step of dissolving the PVC resin and at least phthalate-type additives with a first organic solvent, followed by a second step of liquid-liquid extraction of the phthalates from the already obtained solution through the use of a second organic solvent different from the first organic solvent. US Pat. No. 5,999,623 discloses another example of possible implementation by dissolving the PVC resin and at least phthalate-type additives through the use of a solvent under supercritical conditions, and recovering the phthalates in this same solvent after "breaking" the supercritical conditions.

[0010] The removal or upgrading of phthalate type additives from PVC plastics may be carried out as fully indicated in the publication from , without proceeding via a preliminary step of dissolving said plastics and, in particular, via direct extraction of said phthalates from the solid polymer matrix with a suitable organic solvent. The challenge consists in optimizing the extraction conditions (nature of the solvent, contact time, temperature, pressure, etc.) to achieve the best possible yield of extracted phthalates. This methodology for the removal of phthalates from PVC plastics is frequently used, in particular, to detect and analytically quantify these specific additives in said plastics, although to the applicant's knowledge, no method for regenerating PVC-based objects includes this technique.

[0011] Although crucial to ensure efficient recycling of PVC plastics and to obtain reusable recycled PVC, the extraction of phthalate-type plasticizers is insufficient to ensure the economic viability of a method for regenerating PVC-based objects. The main reason, which is frequently pointed out, is the difficulty of finding an economically viable balance between the costs of the individual operations carried out in the regeneration method and the resale costs of the obtained product (corresponding to the added value). The product consists of a naturally upgradeable phthalate-free PVC-based recycled material and the extracted phthalates, which are themselves only slightly upgradeable. In particular, any regeneration method that includes a step of extracting phthalates from PVC-based objects will lead to the recovery of a mixture of phthalates, which may include phthalates that are not "REACH compliant". The upgrading of the non-REACH compliant phthalates is naturally excluded, and the phthalates would have to be treated as scheduled waste, which would give rise to additional costs. The upgrading of REACH compliant phthalates, although advantageous in itself, is difficult in practical terms, since it involves technically complex and expensive separation / purification steps. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent Application Publication No. 0945481 (JP Patent Publication No. 11-310660) [Patent Document 2] European Patent Application Publication No. 1268628 (JP Patent Publication No. 2003-528191) [Patent Document 3] European Patent Application Publication No. 2276801 (JP Patent Publication No. 2011-520004) [Patent Document 4] European Patent Application Publication No. 1311599 [Patent Document 5] JP 2007-191586 A [Patent Document 6] JP 2007-092035 A [Non-patent literature]

[0013] [Non-Patent Document 1] Uegduler et al., “Challenge and opportunities of solvent-based additive extraction methods for plastic recycling,” Waste Management, 2020, Issue 104, p. 148-182 Summary of the Invention [Means for solving the problem]

[0014] (Summary of the invention) The present invention aims at least in part to overcome the problems of the prior art and is particularly directed towards providing a method for regenerating PVC-based objects that allows the processing of any type of PVC feedstock containing phthalates and their conversion into two products of interest that can be upgraded: recyclable PVC plastics that do not contain certain dialkyl phthalates and phthalates, in particular undesirable phthalates, typically those that are subject to authorization by the European REACH regulation. Another object of the present invention is to make it possible to limit the number of separate steps that are conventionally associated with phthalate separation / purification operations during the recycling of phthalate-containing PVC and thus limit the processing costs.

[0015] Therefore, in order to achieve at least one of the above mentioned objectives, among others, the present invention proposes, according to a first aspect, a method for recovering dialkyl phthalates and reusable target PVC plastics from a PVC feedstock containing at least one phthalate, comprising the following steps: a) solid-liquid extraction of said PVC feedstock in particulate form; said particles of PVC feedstock are subjected to a solid-liquid extraction process according to the empirical formula (C n H 2n+1 O)m by placing in contact with a solvent containing at least one chemical molecule of the ester, ether, ketal or acetal type of Z; n and m are positive integers, n < 4 or n > 8, m is 1 or greater and 3 or less, Z is a group selected from the list consisting of the following elements: R, COOR, CO, CR, CNRR', PO, P, SO, SO2, COR, and HCO, R and R' are independently selected from linear, branched or cyclic alkyl groups, or aryl groups; producing a liquid phase rich in said phthalate and a solid phase comprising said phthalate-poor PVC plastic; b) the phthalate of the liquid phase, n H 2n+1 Chemical conversion of )2 to dialkyl phthalates; empirical formula (C n H 2n+1 O) m by transesterification with said chemical molecule of ester, ether, ketal or acetal type of Z; enriching said liquid phase with said dialkyl phthalate; c) solid-liquid separation between said solid phase and said liquid phase; producing at least one solids stream comprising said phthalate-lean PVC plastic and recovering said target PVC plastic; d) liquid-liquid separation of said liquid phase; producing at least a first liquid effluent comprising said dialkyl phthalate and a second liquid effluent comprising at least said solvent.

[0016] One advantage of the present invention lies in the ability of the method to convert, by means of chemical transesterification, a mixture of phthalates initially trapped in the polymer matrix of various objects based on PVC plastics, into a single REACH-compliant and upgradeable DAP-type phthalate product, regardless of the composition of said mixture (i.e. regardless of the nature and origin of the various phthalates), despite the possible presence of numerous other additives. The production of a single specific DAP product from a mixture of phthalates also makes it possible to limit the number of individual steps involved in the separation / purification operations and therefore the costs.

[0017] According to a first variant, steps a) and b) are carried out within the same individual operation.

[0018] According to a second variant, alternative to the first, steps a) and b) form the object of two distinct and separate operations, step a) producing a stream comprising a liquid phase and a solid phase.

[0019] According to this second variant, step c) may be carried out between steps a) and b), and the stream comprising the liquid phase and said solid phase obtained from step a) is optionally sent to a solid-liquid separation step c) to give a stream comprising said phthalate-depleted PVC plastic and a first liquid stream comprising a liquid phase, which first liquid stream is sent to step b).

[0020] According to one or more embodiments, the method also comprises an additional step f1) of chemical conversion, which step f1) comprises converting the unconverted and / or partially converted phthalates of the formula C6H4(COOC) n H 2n+1 ) 2 to dialkyl phthalate with the solvent, said step f1) being carried out between steps c) and d) by sending said liquid phase obtained at the end of all steps a), b) and c) to a first additional transesterification reactor, n H 2n+1 2) producing a second liquid stream enriched in said dialkyl phthalate, said second liquid stream being sent to step d).

[0021] According to one or more embodiments, the solvent is fed to a first additional transesterification reactor and / or at least a portion of the second liquid effluent from step d) comprising at least the solvent is recycled to the first additional transesterification reactor.

[0022] According to one or more embodiments, in step d), the first effluent consists essentially of the dialkyl phthalate.

[0023] According to one or more embodiments, the liquid-liquid separation step d) also gives rise to a third effluent comprising by-products of ester, ether, ketal or acetal type obtained during step b), and optionally also a fourth effluent comprising said phthalates partially converted and / or not converted in step b) and optionally other soluble impurities, said first liquid effluent consisting essentially of said dialkyl phthalates and said second liquid effluent consisting essentially of said solvent.

[0024] According to one or more embodiments, the liquid-liquid separation step d) also gives rise to a third effluent comprising by-products of ester, ether, ketal or acetal type obtained during step b), said first liquid effluent comprising said dialkyl phthalate, phthalates partially and / or not converted in step b) and optionally soluble impurities, and said second liquid effluent consisting essentially of said solvent, the process also comprising the steps of: e) purifying said first liquid effluent to produce a liquid product consisting essentially of said dialkyl phthalate and a liquid residue containing said phthalates partially and / or unconverted in step b) and optionally said soluble impurities.

[0025] According to one or more embodiments, the method also comprises an additional step f2) of chemical conversion, which step f2) comprises converting the unconverted and / or partially converted phthalates of step b) into phthalates of formula C6H4(COOC n H 2n+1 )2 with the solvent to dialkyl phthalate, said step f2) being carried out after step e) by sending said liquid residue to a second additional transesterification reactor, n H 2n+1 ) producing a third liquid stream enriched in said dialkyl phthalate of 2, said third liquid stream being returned to step d).

[0026] According to one or more embodiments, the solvent is fed to a second additional transesterification reactor and / or at least a portion of the second liquid effluent from step d) comprising at least the solvent is recycled to the second additional transesterification reactor.

[0027] According to one or more embodiments, the method also comprises recycling at least a portion of the liquid residue to step b) and / or to an additional step f1), which comprises converting the unconverted and / or partially converted phthalates of formula C6H4(COOC) n H 2n+1 2) by transesterification with the solvent to dialkyl phthalate, said step f1) being carried out between steps c) and d) by sending said liquid phase obtained at the end of all steps a), b) and c) to a first additional transesterification reactor, n H 2n+1 2) producing a second liquid stream enriched in said dialkyl phthalate, said second liquid stream being sent to step d).

[0028] According to one or more embodiments, the second liquid effluent from step d) comprising at least said solvent is at least partially recycled to step a) and / or step b).

[0029] According to one or more embodiments, the solids stream comprising the phthalate-poor PVC plastic is at least partially recycled to step a).

[0030] According to one or more embodiments, the solvent chemical molecule has the formula (C n H 2n+1 O) m wherein n is n<4 or n>8, and m is 1 or more and 3 or less, and the ester is preferably an ester of the formula (C n H 2n+1O)COR carboxylic acid esters of formula (C n H 2n+1 Carbonate of formula (C n H 2n+1 O)3CR orthoester of formula (C n H 2n+1 O)CNRR′ imino esters of formula (C n H 2n+1 O)3P, a phosphite of formula (C n H 2n+1 O)3PO, a phosphate ester of formula (C n H 2n+1 Sulfite of the formula (C n H 2n+1 O)2SO2 sulfate esters, and mixtures thereof, provided that the esters contained in said mixtures are selected from the list consisting of alkoxy groups C n H 2n+1 O, where the value of n is exactly the same, and more preferentially the chemical molecule of the solvent (9) has the formula (C n H 2n+1 O)COR carboxylic acid esters, where n is n<4 or n>8, preferably selected from the list consisting of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, nonyl acetate (which may be linear or branched), decyl acetate (which may be linear or branched), methyl propanoate, ethyl propanoate, propyl propanoate, isopropyl propanoate, nonyl propanoate (which may be linear or branched) and decyl propanoate (which may be linear or branched), preferably methyl acetate or methyl propanoate.

[0031] According to one or more embodiments, the solvent chemical molecule has the formula C n H 2n+1 O) R ethers, where n<4 or n>8, preferably selected from the list consisting of dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dinonyl ether (which may be linear or branched), didecyl ether (which may be linear or branched), more preferentially dimethyl ether or diethyl ether.

[0032] According to one or more embodiments, the solvent chemical molecules each have the formula (C n H 2n+1 O)2CRR' or (C n H 2n+1 O) a ketal or acetal of 2CRH, where n<4 or n>8, preferably selected from the list consisting of dimethylal, 2,2-dimethoxypropane, 2,2-dimethoxybutane, diethylacetal, 2,2-diethoxypropane and 2,2-dipropoxypropane, more preferentially dimethylal, 2,2-dimethoxypropane or 2,2-dimethoxybutane.

[0033] According to one or more embodiments, the solvent chemical molecule is methyl propanoate and the dialkyl phthalate is dimethyl phthalate.

[0034] According to one or more embodiments, the chemical conversion carried out by transesterification in step b) and optionally in steps f1) and / or f2) is carried out using a transesterification catalyst, which is preferably selected from the list consisting of inorganic or organic basic or acidic Brönsted homogeneous catalysts, Lewis acids, and heterogeneous catalysts formed by alkaline earth metal oxides, or alkali metal and / or alkaline earth metal carbonates or hydrogen carbonates, or alkali metals supported on alumina or zeolites, or zinc oxide and mixtures thereof with other oxides, or ion exchange resins.

[0035] According to one or more embodiments, the at least one phthalate of the PVC feedstock is a phthalate of empirical formula CH(COOR1)(COOR2), where an ester group is in the ortho position of the benzene nucleus, and R1 or R2 is independently selected from one of the members of the group consisting of linear or branched or cyclic alkyl chains, linear or branched alkoxyalkyl chains, or aryl or alkylaryl chains, with R1 and / or R2 preferably containing 1 to 20 carbon atoms, or even 1 to 15 carbon atoms.

[0036] According to one or more embodiments, the target PVC plastic is substantially free of said phthalates, preferably containing less than 0.1% by weight total of phthalates selected from the list consisting of dibutyl phthalate, dioctyl or diethylhexyl phthalate, benzyl butyl phthalate, dibutyl phthalate, diisobutyl phthalate, dipentyl phthalate, diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, and mixtures thereof.

[0037] According to one or more embodiments, step b) and, optionally, steps f1) and / or f2) are carried out at a temperature between room temperature and 200° C., preferably between 40° C. and 180° C., at a pressure between atmospheric pressure and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, for a period between 1 minute and 10 hours, preferably between 10 minutes and 4 hours.

[0038] According to one or more embodiments, step a) and / or step b), and optionally steps f1) and / or f2), are carried out such that the molar ratio between the amount of solvent (9) and the amount of phthalate to be extracted or converted is between 2 and 250, preferably between 4 and 90.

[0039] According to a second aspect, the present invention relates to a method for recycling PVC-based objects containing at least one phthalate, the method comprising: - conditioning the PVC-based objects, which at least includes grinding or shredding the PVC-based objects to form a PVC feedstock in particulate form; - Recovery of dialkyl phthalates and recyclable target PVC plastics from said PVC feedstock in particulate form according to the present invention.

[0040] According to a third aspect, the present invention relates to a method for producing a flexible PVC-based object comprising recycled PVC plastic and / or dialkyl phthalate obtained via the method for recovering dialkyl phthalate and reusable target PVC plastic according to the present invention.

[0041] Other objects and advantages of the present invention will become apparent on reading the following description of examples of particular implementations of the invention, given by way of non-limiting examples, this description being made with reference to the accompanying drawings, in which: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] (List of Drawings) FIG. 1 is a scheme of a method according to one embodiment of the invention, comprising steps a), b), c) and d).

[0043] FIG. 2 is a scheme of a process according to another embodiment, comprising steps a), b), c) and d), in which in step d) a separation is carried out between DAP, the solvent, the by-products obtained in step b) of type esters, ethers, ketals or acetals, and the partially converted and / or unconverted phthalates, optionally in a mixture with soluble impurities.

[0044] FIG. 3 is a scheme of the process according to the embodiment illustrated in FIG. 1 or FIG. 2, comprising steps a), b), c) and d), showing the implementation of the transesterification (f1) and other optional steps of recycling the various streams.

[0045] FIG. 4 is a scheme of a process according to another embodiment of the invention, comprising steps a), b), c) and d), and also a step e) of purification of the first effluent obtained in step d) comprising DAP.

[0046] FIG. 5 is a scheme of the process according to the embodiment illustrated in FIG. 4, showing the implementation of transesterification (f1; f2) and other optional steps of recycling the various streams.

[0047] FIG. 6 shows a scheme of a process according to a preferred embodiment of the invention, comprising the implementation of steps a) and b) within the same separate operation (first variant of the process according to the invention), a step e) of purification of the first effluent obtained in step d) comprising DAP and an additional step f2) of transesterification of the residue obtained from step e).

[0048] FIG. 7 is a scheme of a method according to another embodiment of the invention, comprising steps a), b), c) and d), steps a) and b) forming the object of two distinct and separate operations (second variant of the method according to the invention) and step c) being carried out between steps a) and b).

[0049] FIG. 8 is a scheme of a method according to a preferred embodiment similar to that illustrated in FIG. 7, comprising a step e) of purification of the first effluent obtained in step d) containing the DAP and an additional step f2) of transesterification of the residue obtained from step e).

[0050] In the drawings, the same reference numbers represent the same or similar elements.

[0051] (Description of the embodiment) (term) Certain definitions are provided below, although further details regarding the subject matter defined below may be provided later in the specification.

[0052] The term "PVC-based object" means an object, generally a consumer object, which comprises, and preferably consists of, at least one PVC plastic.

[0053] The term "polyvinyl chloride plastic", also known as PVC plastic or simply PVC, refers to the combination of PVC polymer, also known as PVC resin, with various additives that are selected depending on the functionality required of the PVC plastic, which are themselves selected depending on the intended use.

[0054] The PVC polymers are derived from the radical polymerization of vinyl chloride (VCM), a monomer which is itself derived from chlorine and ethylene. Depending on the implementation of the polymerization, four families of PVC resins may be used: 1) suspension PVC or S-PVC resins (suspension polymerization of VCM), 2) emulsion PVC or PVC "paste" resins (emulsion polymerization), 3) bulk PVC or M-PVC resins (bulk polymerization) and 4) perchlorinated PVC or C-PVC resins obtained by perchlorination as a post-treatment on the preceding resin.

[0055] Said additives contained in the composition of PVC plastics can be organic or macromolecules or inorganic (nano)particles, and are used depending on the properties they impart to the PVC resin: resistance to heat, light or mechanical stress (stabilizers), flexibility (plasticizers), processability (lubricants), colorability (dyes / pigments), etc.

[0056] The term "phthalate" refers to a group of chemical products formed by dicarboxylic esters of o-phthalic acid. They consist of a benzene nucleus and two carboxylic ester groups placed in the ortho positions of the benzene nucleus. They have the following formula:

[0057] [ka]

[0058] or by the empirical formula CH(COOR)(COOR), where R and R are independently selected from one of the members of the group consisting of a linear, branched or cyclic alkyl chain, a linear or branched alkoxyalkyl chain, or an aryl or alkylaryl group. The alkyl, alkoxyalkyl, aryl or alkylaryl chain may typically contain 1 to 20 carbon atoms, or even 1 to 15 carbon atoms.

[0059] For example, R1 and / or R2 may be selected from the group ethyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, isodecyl, methoxyethyl and benzyl. Phthalates are commonly used as plasticizers for plastics, in particular for PVC type plastics, to make them flexible, among other things.

[0060] In the present description, the term "transesterification" refers to the conversion of at least one carboxylic acid ester group -COOR1 or -COOR2 of a phthalate as defined above to a new carboxylic acid ester group -COO(C n H 2n+1 ), where n<4 or n>8, regardless of the reagent used.

[0061] In this description, the term "dialkyl phthalate" (DAP) refers to a compound having the empirical formula C6H4(COOC n H 2n+1 ) 2, which refers to the product of at least one plasticizer of the phthalate type (in particular of the above empirical formula C6H4(COOR1)(COOR2)) present in the PVC-based object and a compound of the empirical formula (C n H 2n+1 O) mThe resulting chemical molecule is an ester exchange reaction between Z and any chemical molecule of the ester, ether, ketal or acetal type, which may be referred to in the remainder of this description as "reagent" or "solvent", where n and m are positive integers, n is n<4 or n>8, m is 1 or more and 3 or less, and Z is a group selected from the list consisting of one of the following elements: R, COOR, CO, CR, CNRR', PO, P, SO, SO2, COR and HCO, where R and R' are independently selected from alkyl or aryl groups (linear, branched or cyclic) and contain, for example, 1 to 20 carbon atoms, or even 1 to 15 carbon atoms. Said chemical molecules are described in more detail later in this description. Dimethyl phthalate is an example of DAP.

[0062] The term "ester, ether, ketal or acetal type by-products" (BP) refers to by-products of formula R1OZ or R2OZ, which are the product of at least one plasticizer of the phthalate type (in particular of the empirical formula C6H4(COOR1)(COOR2) above) present in the PVC-based object and a reagent (of the empirical formula (C n H 2n+1 O) m Z is a chemical molecule of the ester, ether, ketal or acetal type with Z. R1 and R2 are synonymous with R1 and R2 of the phthalate. Z is synonymous with Z of the reagent.

[0063] The term "intermediate alkyl phthalate" (IAP) refers to a compound with the empirical formula C6H4(COOR1)(COOC n H 2n+1 ) or C6H4(COOR2)(COOC n H 2n+1 ) by-product of the reaction of at least one plasticizer of the phthalate type (of empirical formula C6H4(COOR1)(COOR2) as defined above) present in the PVC-based object with a reagent (of empirical formula (C n H 2n+1 O) mZ is an ester, ether, ketal or acetal type chemical molecule of Z. R1 and R2 are synonymous with R1 and R2 of the phthalate. Z is synonymous with Z of the reagent.

[0064] The term "recyclable target PVC plastic" means in particular "phthalate-free PVC", i.e. a solid comprising at least one PVC resin supplemented with at least one of the additives originally present in the PVC plastic of the PVC feedstock treated according to the present invention, from which the phthalates have been extracted and converted according to the present invention into the form of at least one dialkyl phthalate. The term "phthalate-free" means in particular that the solid PVC obtained as product of the process according to the invention contains less than 0.1% by weight in total of phthalates subject to the authorization in Europe according to the REACH regulation (Annex XIV of Regulation (EC) Number 1907 / 2006 of the European Parliament and of the Council of 18 December 2006), in particular less than 0.1% by weight in total of phthalates selected from the list consisting of the following phthalates, where the phthalates are from the list consisting of the following phthalates: dibutyl phthalate (DBP), dioctyl phthalate 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, and bis(2-methoxyethyl) phthalate, which may be utilized alone or in mixtures.

[0065] In this description, the term "greater than..." is understood to be strictly greater than and is symbolized by the symbol ">", and the term "less than..." is understood to be strictly less than and is symbolized by the symbol "<".

[0066] In this specification, the indices "n" and "m" in the cited chemical formulae are positive integers (i.e. strictly greater than 0). According to the present invention, n is less than 4 or greater than 8, preferably less than or equal to 20, or even less than or equal to 15. According to the present invention, m is an integer greater than or equal to 1 and less than or equal to 3.

[0067] In this description, the term "room temperature" (rt) means a temperature typically of 20°C ± 5°C, and the term "atmospheric pressure" means a pressure of 0.101325 MPa.

[0068] In this description, the term "comprise" is synonymous with (has the same meaning as) the terms "include" and "contain" and is inclusive or open-ended and does not exclude other elements not specified. The term "comprise" is understood to encompass the exclusive and closed term "consist."

[0069] In this description, the expression "between ... and ..." means, unless otherwise stated, that both limits of the interval are included in the stated range of values.

[0070] In the present description, various ranges of parameters for a given process, such as pressure ranges and temperature ranges, may be used alone or in combination. For example, in the present description, a range of preferred pressure values ​​may be combined with a more preferred range of temperature values.

[0071] In the following text, certain embodiments of the present invention may be described, which may be implemented separately or in combination together, without any limitation of combination where this is technically possible.

[0072] The following description of the process according to the invention refers to schemes in Figures 1 to 8, which show various implementations of the process according to the invention.

[0073] According to the present invention, the method for recovering DAP and recyclable target PVC plastic from a PVC feedstock containing at least one phthalate may comprise or consist of the following steps: a) solid-liquid extraction of the PVC feedstock (1) in particulate form; the particles of PVC feedstock are subjected to extraction with esters, ethers, ketals or acetals of the empirical formula (C n H 2n+1 O) m wherein n and m are positive integers, n<4 or n>8, m is 1 or greater and 3 or less, and Z is a group selected from the list consisting of one of the following elements: R, COOR, CO, CR, CNRR', PO, P, SO, SO2, COR, and HCO, and R and R' are independently selected from linear, branched or cyclic alkyl groups, or aryl groups; producing a phthalate-rich liquid phase and a solid phase comprising phthalate-poor PVC plastic; b) Formula C6H4(COOC n H 2n+1 Chemical conversion of the phthalates in the liquid phase to dialkyl phthalates of the ester, ether, ketal or acetal type with the empirical formula (C n H 2n+1 O) m by transesterification with said chemical molecule of Z; enriching said liquid phase with said dialkyl phthalate; c) solid-liquid separation between said solid phase and said liquid phase; producing at least one solid stream (6) comprising said phthalate-lean PVC plastic and recovering said target PVC plastic; d) liquid-liquid separation of said liquid phase (4); producing at least a first liquid effluent comprising said dialkyl phthalate ((5) or (14)) and a second liquid effluent comprising at least said solvent ((7) or (12)).

[0074] (Feed material) The process according to the invention is fed with a feedstock known as "PVC feedstock" (1) which contains at least one PVC plastic, which necessarily contains at least one phthalate as described in the present invention.

[0075] The PVC plastic may contain at least 0.1% by weight phthalate, or even at least 1% by weight phthalate, or alternatively at least 5% by weight phthalate. In general, the PVC plastic advantageously contains less than 60% by weight phthalate, typically less than 30% by weight phthalate.

[0076] Said PVC feedstock is advantageously a feedstock of PVC to be recycled of the "production scrap" type, i.e. waste resulting from the process for producing PVC polymer during its polymerization or from PVC plastic during its compounding / molding or a feedstock of PVC-based objects during their manufacture, or a feedstock of the "post-consumer waste" type, i.e. waste resulting after consumption by users of said PVC-based objects.

[0077] In particular, the PVC feedstock to be recycled may originate from any existing collection and sorting channels or networks for production scrap and / or post-consumer waste, especially collection and sorting channels or networks specific to plastic waste, which make it possible to segregate at least one PVC plastic-based stream containing at least one phthalate.

[0078] Thus, the PVC feedstock, typically of the "production scrap" and / or "post-consumer waste" type, is generally obtained from the main fields of application in which PVC plastics are used, such as, non-exhaustively, the building and construction sector, packaging, automotive, electrical and electronic equipment, sports, medical equipment, etc. Preferably, the PVC feedstock is obtained from the building and construction sector. More precisely, PVC-based objects are generally used in these fields as various rigid profiles (casings for windows, doors, sunshades, roller blinds), pipes and connections, and rigid bottles, plates and films, flexible films and sheets, flexible tubes and profiles, cables, flooring, coated fabrics, etc. Preferably, the PVC-based objects forming the PVC feedstock comprise at least one "flexible" PVC, i.e. PVC containing an additive of the plasticizer type, preferably of the phthalate type, but this also applies, for example, to the following PVC-based objects: flexible films and sheets, flexible tubes and profiles, cables, flooring, coated fabrics, etc.

[0079] Advantageously, the PVC feedstock comprises at least 50% by weight, preferably at least 70% by weight, preferably at least 90% by weight, even more preferably at least 95% by weight of PVC plastic comprising at least one phthalate.

[0080] Preferably, the PVC feedstock comprises "flexible" PVC, ie, PVC containing additives of the plasticizer type, preferably of the phthalate type.

[0081] Even more preferably, the PVC feedstock comprises predominantly or even exclusively "flexible" PVC, ie PVC containing additives of the plasticizer type, preferably of the phthalate type.

[0082] The PVC feedstock processed in the method for recovering DAP and reusable target PVC plastic according to the invention is in particulate form. Therefore, if the PVC feedstock is in an original form that is typical of manufacturing scrap or post-consumer waste, especially in the latter case, in the original form of PVC-based objects, it first undergoes a conditioning step that includes at least crushing or chopping to form a PVC feedstock in particulate form. Depending on the channels and / or networks from which these manufacturing scraps and / or PVC-based objects at the end of their useful life come, the PVC waste may be crushed and / or washed and / or may undergo any other conditioning step described below to form a PVC feedstock in particulate form suitable for the method according to the invention. For example, the PVC feedstock may advantageously be in the form of a crushed and possibly washed material, the largest dimension of which is less than 20 cm, preferably less than 10 cm, preferably less than 1 cm, even more preferably less than 5 mm. The PVC feedstock may advantageously be in the form of a finely divided solid, i.e. in the form of particles preferably having an average size of less than 1 mm, for example between 10 and 800 micrometers (μm), the average size advantageously corresponding to the average diameter of the spheres that surround said particles.

[0083] The term "PVC feedstock in particulate form" therefore means particles of PVC plastic as already defined, typically having an average size of 10 μm to 20 cm, for example particles of crushed material type having an average size of 1 mm to 20 cm, preferably 1 mm to 10 cm, more preferentially 1 mm to 1 cm, even more preferentially 1 mm to 5 mm, or particles resulting from micronization (very fine grinding resulting in a powder) having an average size of less than 1 mm, preferably 10 μm to 800 μm.

[0084] Preferably, the PVC feedstock treated in the process according to the invention is in particulate form of a crushed material type, preferably particles having an average size of 1 mm to 5 mm, or particles resulting from micronization (very fine grinding resulting in a powder) having an average size of less than 1 mm.

[0085] PVC feedstock may also contain "macroscopic" impurities such as glass, metal, plastics other than PVC (e.g. PET, etc.), wood, paper, cardboard, inorganic components, etc. Advantageously, the PVC feedstock contains no more than 50% by weight of "macroscopic" impurities, preferably no more than 30% by weight, preferably no more than 10% by weight, even more preferably no more than 5% by weight.

[0086] Advantageously, the PVC feedstock in particulate form has a water content of less than or equal to 0.3% by weight, preferably less than or equal to 0.1% by weight.

[0087] The various steps of the method according to the invention leading to the DAP and to the target recyclable PVC plastic are detailed in the following paragraphs.

[0088] (Optional Preliminary Step to Condition PVC Feedstock) According to the invention, the method may comprise a preliminary step (not shown in the figures) of conditioning the PVC feedstock, which comprises at least one step of grinding or shredding the PVC feedstock to form a PVC feedstock in solid particulate form as defined above, which PVC feedstock in particulate form may be sent to a solid-liquid extraction step a). This preconditioning step may comprise one or more of the steps mentioned in the following non-exhaustive list: grinding by micronization, screening, overscreening, washing, drying, etc. Depending on the nature of the PVC feedstock to be treated, the step or steps comprised in the preconditioning step, and their possible frequency and sequence, will be chosen, inter alia, by the person skilled in the art so as to limit the amount of macroscopic impurities and to reduce the size of the solid elements that originally constitute the PVC feedstock.

[0089] For example, the preconditioning step makes it possible to provide a PVC feedstock in particulate form, e.g. a ground and washed material having an average size of less than 5 mm, the macroscopic impurities content of which is preferably less than 10% by weight, more preferably less than 5% by weight. The preconditioned PVC feedstock may be in the form of finely divided solid particles, i.e. particulates having an average size of less than 1 mm, e.g. between 10 μm and 800 μm.

[0090] The step of preconditioning the PVC feedstock preferably comprises at least one step of drying the PVC feedstock, already in solid particulate form of ad hoc size and macroscopic impurity content, so that said PVC feedstock has a residual water content of less than or equal to 0.3% by weight, preferably less than or equal to 0.1% by weight.

[0091] (Step a) of solid-liquid extraction of phthalates) The process according to the invention comprises a step a) of solid-liquid extraction of one or more phthalates of a PVC feedstock (1) in particulate form, which step a) is carried out by placing said feedstock (1) in contact with a solvent (9), which solvent (9) is capable of extracting one or more phthalates of the empirical formula (C n H 2n+1 O) m The process comprises, and preferably consists of, a chemical molecule Z, where n<4 or n>8, m is 1 or more and 3 or less, Z being a group selected from the list consisting of one of the following elements: R, COOR, CO, CR, CNRR', PO, P, SO, SO2, COR, and HCO, where R and R' are independently selected from alkyl or aryl groups (linear, branched or cyclic), for example containing 1 to 20 carbon atoms, or even 1 to 15 carbon atoms, to obtain an effluent (2) comprising at least a liquid phase and a solid phase.

[0092] In particular, the formula (C n H 2n+1 O) m During Z: When m=1, Z is selected from among R, COOR, COR, CNRR′, HCO: When m=2, Z is selected from CO, SO, SO2: If m=3, Z is chosen among PO, P, and CR.

[0093] The liquid phase is then enriched in the one or more phthalates and the solid phase comprises PVC plastic that is depleted in the one or more phthalates.

[0094] A specific choice of n chemical molecule of the solvent ester, ether, ketal or acetal type (alkyl chain C of C4, C5, C6, C7, and C8 chains) n H 2n+1 (excluding option a) makes it possible, during step b), to convert said phthalates by transesterification with said chemical molecules of ester, ether, ketal or acetal type into at least one DAP as defined above in this description, which are not among the unwanted phthalates, e.g. those that are not subject to authorization according to the aforementioned REACH regulation.

[0095] According to one or more embodiments, the chemical molecule of the ester, ether, ketal or acetal type has the empirical formula (C n H 2n+1 O) m Z, where n<4, preferably n=1 or n=2, even more preferably n=1.

[0096] According to one or more embodiments, the chemical molecule of the ester, ether, ketal or acetal type has the empirical formula (C n H 2n+1 O) m Z, where n>8 and n is 20 or less, or further, n is 15 or less.

[0097] Preferably, n is an integer, n<4, more preferably n is equal to 1 or 2.

[0098] According to one or more embodiments, the chemical molecule has one or more of the formula (C n H 2n+1 O) m where n<4 or n>8 and m is 1 or more and 3 or less.

[0099] The esters are preferably those of the list consisting of the following: n H 2n+1 O)COR carboxylic acid esters of formula (C n H 2n+1 Carbonate of formula (C n H 2n+1 O)3CR orthoester of formula (C n H 2n+1 O)CNRR′ imino esters of formula (C n H 2n+1 O)3P, a phosphite of formula (C n H 2n+1 O)3PO, a phosphate ester of formula (C n H 2n+1 Sulfite of the formula (C n H 2n+1 O)2SO2, a sulfate ester of formula (C n H 2n+1 O) HCO formic acid esters (alkyl formates), such as ethyl or methyl formate, and mixtures thereof, provided that the esters contained in said mixtures contain alkoxy groups C with exactly the same value of n. n H 2n+1 O. The list of esters is not exhaustive. The groups R and R' are independently selected from alkyl or aryl groups (linear, branched or cyclic) containing, for example, 1 to 20 carbon atoms, or even 1 to 15 carbon atoms.

[0100] Preferably, said chemical molecule of ester type has the formula (C n H 2n+1O)COR carboxylic acid esters, where n is such that n<4 or n>8, selected from the list consisting of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, nonyl acetate (linear or branched), decyl acetate (linear or branched), methyl propanoate, ethyl propanoate, propyl propanoate, isopropyl propanoate, nonyl propanoate (linear or branched), decyl propanoate (linear or branched). Even more preferably, said chemical molecule of ester type is methyl acetate or methyl propanoate.

[0101] According to one or more embodiments, the chemical molecule has the formula (C n H 2n+1 O) R ethers, where n<4 or n>8, preferably selected from the list consisting of: dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dinonyl ether (linear or branched), didecyl ether (linear or branched). Preferably, said chemical molecule is dimethyl ether or diethyl ether.

[0102] A suitable ether can also be cyclopentyl methyl ether (CPME).

[0103] According to one or more other embodiments, the chemical molecules each have the formula (C n H 2n+1 O)2CRR' or (C n H 2n+1O) Ketals or acetals of 2CRH, where n<4 or n>8, R and R' are independently selected from alkyl or aryl groups (linear, branched or cyclic), said ketal or acetal chemical molecule preferably being selected from the list consisting of: dimethylal, 2,2-dimethoxypropane, 2,2-dimethoxybutane, diethylacetal, 2,2-diethoxypropane and 2,2-dipropoxypropane. Preferably, said chemical molecule of ketal or acetal type is dimethylal, 2,2-dimethoxypropane or 2,2-dimethoxybutane.

[0104] Preferably, step a) of solid-liquid extraction of one or more phthalates of PVC feedstock (1) is carried out by placing said feedstock (1) in particulate form in contact with methyl acetate or methyl propanoate, e.g. methyl propanoate, in which case the DAP produced by the process is dimethyl phthalate (DMP).

[0105] Step a) of the solid-liquid extraction of the one or more phthalates of the PVC feedstock (1) is preferably carried out under the following operating conditions: the temperature is between room temperature and 200°C, preferably between 40°C and 180°C, more preferably between 60°C and 150°C, the pressure is between atmospheric pressure and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, more preferably between atmospheric pressure and 2.0 MPa, and the residence time is between 1 minute and 10 hours, preferably between 10 minutes and 4 hours, more preferably between 10 minutes and 2 hours.

[0106] Preferably, step a) is carried out such that the molar ratio between the amount of chemical molecules of ester, ether, ketal or acetal type of the solvent (9) and the amount of one or more phthalates to be extracted from the PVC feedstock (1) is between 2 and 250, preferably between 4 and 90, even more preferably between 4 and 30.

[0107] The reactor of step a) of the process according to the invention may advantageously be a reactor of the type stirred by a mechanical stirring system and / or a recirculation loop and / or fluidization, for example a perfectly stirred reactor of discontinuous or continuous type, or a reactor of the rotating drum type.

[0108] In terms of implementation, the particulate form PVC feedstock (1) and the solvent (9) are advantageously mixed.

[0109] According to a first option, said mixing may be carried out prior to the introduction of the feedstock and the solvent into the reactor of the solid-liquid extraction step a), in which case said mixture may be formed in a mixer and then introduced into the reactor, said reactor being maintained at the desired pressure and temperature.

[0110] According to a second option, the PVC feedstock (1) in particulate form and the solvent (9) may be introduced separately into the reactor of step a) of the process according to the invention. The solid PVC feedstock and the solvent are then preferably injected into the reactor via two separate lines, one allowing the injection of the solvent (9) and the other allowing the injection of the solid PVC feedstock (1) in particulate form. In this case, a mixture of PVC feedstock and solvent is formed directly in the reactor.

[0111] According to the invention, said solid-liquid extraction step a) makes it possible to obtain at least one effluent (2) comprising at least a liquid phase containing at least the extracted phthalates and at least a solid phase containing phthalate-poor, preferably phthalate-free, PVC plastic.

[0112] (Step b) of chemical conversion of the phthalate) The method according to the invention comprises the step of catalysing one or more phthalates of formula C6H4(COOC n H 2n+1)2 into at least one DAP of empirical formula (C) of the type ester, ether, ketal or acetal, in a solvent (9) as defined above in step a) (including all preferred molecules as similarly defined in step a) for said solvent (9)). n H 2n+1 O) m This is carried out by a transesterification reaction between the chemical molecule Z, preferably in the liquid phase.

[0113] The phthalate or phthalates present in the liquid phase at the end of step a) have the formula C6H4(COOC n H 2n+1 Step b) of the chemical conversion by transesterification of 2 to DAP is preferably carried out under the following operating conditions: the temperature is between room temperature and 200° C., preferably between 40° C. and 180° C., more preferably between 60° C. and 150° C., the pressure is between atmospheric pressure and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, more preferably between atmospheric pressure and 2.0 MPa, and the residence time is between 1 min and 10 h, preferably between 10 min and 4 h, more preferably between 10 min and 2 h.

[0114] Preferably, step b) is carried out such that the molar ratio between the amount of chemical molecules of ester, ether, ketal or acetal type in solvent (9) and the amount of phthalate(s) to be converted in the liquid phase containing the phthalate(s) extracted at the end of step a) is between 2 and 250, preferably between 4 and 90, even more preferably between 4 and 30.

[0115] The solvent used to carry out step b) is the same as that used to carry out step a).

[0116] Preferably, the one or more phthalates extracted in step a) have the formula C6H4(COOC n H 2n+1Said step b) of chemical conversion by transesterification of 2 to DAP is carried out in the presence of a transesterification catalyst, which is advantageously introduced into the reaction medium.

[0117] The transesterification catalyst thus used is, for example, selected from the following non-exhaustive list of catalysts known to the person skilled in the art, preferably from the list consisting of: - homogeneous catalysts, such as basic catalysts (sodium or potassium hydroxide, sodium or potassium methoxide, sodium or potassium carbonate, etc.), mineral Brønsted acid catalysts (hydrochloric acid, sulfuric acid, phosphoric acid, etc.), organic Brønsted acid catalysts (methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, etc.), Lewis acid catalysts, especially those containing boron compounds (BH3, BF3) and aluminum compounds (AlF3, AlCl3), and organometallic compounds; Heterogeneous catalysts, such as alkaline earth metal oxides (CaO, BaO, etc.), alkali metal and / or alkaline earth metal carbonates or hydrogen carbonates (CaCO3, etc.), alkali metals supported on alumina or zeolites, zinc oxide and their mixtures with other oxides (e.g. zinc oxide and alumina), ion exchange resins (cationic or anionic), such as sulfonic acid resins, etc.

[0118] For example, the catalyst used according to the invention is a homogeneous catalyst, especially a homogeneous catalyst of the basic catalytic type, for example sodium methoxide.

[0119] The chemical molecule is an ester as defined above under step a), in particular a compound of the formula (C n H 2n+1In the case of esters of O)COR (n with n<4 or n>8), preferably esters selected from the list consisting of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, nonyl acetate (linear or branched), decyl acetate (linear or branched), methyl propanoate, ethyl propanoate, propyl propanoate, isopropyl propanoate, nonyl propanoate (linear or branched), decyl propanoate (linear or branched), e.g. methyl acetate or ethyl acetate, suitable catalysts are homogeneous catalysts, in particular homogeneous catalysts of basic type such as sodium methoxide.

[0120] The chemical molecule is an ether as defined above under step a), in particular a compound of the formula (C n H 2n+1 O) In the case of an ether of R (n is n<4 or n>8), preferably an ether selected from the list consisting of dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dinonyl ether (linear or branched), didecyl ether (linear or branched), and cyclopentyl methyl ether, for example dimethyl ether or diethyl ether, the suitable catalyst is a homogeneous catalyst, in particular an acidic catalyst, typically an organic Bronsted acid catalyst such as methanesulfonic acid, trifluoromethanesulfonic acid, or trifluoroacetic acid.

[0121] The chemical molecule is a ketal or acetal as defined above under step a), in particular having the formula (C n H 2n+1 O)2CRR' or (C n H 2n+1O) ketals or acetals where n is n<4 or n>8 and R and R' are independently selected from (linear, branched or cyclic) alkyl or aryl groups, and said ketal or acetal chemical molecule is preferably selected from the list consisting of: dimethylal, 2,2-dimethoxypropane, 2,2-dimethoxybutane, diethylacetal, 2,2-diethoxypropane and 2,2-dipropoxypropane, e.g. dimethylal, suitable catalysts are homogeneous catalysts, in particular acid catalysts, typically organic Bronsted acid catalysts such as methanesulfonic acid, trifluoromethanesulfonic acid, or trifluoroacetic acid.

[0122] Preferably, the amount of catalyst introduced is such that the mass ratio between the catalyst and the phthalate or phthalates to be converted is between 0.5% and 15% by weight, preferably between 1% and 10% by weight, even more preferably between 1% and 8% by weight.

[0123] The catalyst, whether homogeneous or heterogeneous, may be recycled and / or removed in the process by methods well known to those skilled in the art, preferably recycled. It may be isolated, removed or recycled to downstream steps of the process, preferably to step c), to step d) and / or to step e) or to any other dedicated step for transesterification.

[0124] The reactor of step b) of the process according to the invention may advantageously be a reactor of the type stirred by a mechanical stirring system and / or by a recirculation loop and / or by fluidization, for example a perfectly stirred reactor of discontinuous or continuous type, or a reactor of the rotating drum type.

[0125] According to the invention, said step b) of conversion of phthalates results in the formation of phthalates of formula C6H4(COOC) obtained after transesterification. n H 2n+1It is then possible to obtain at least one liquid phase which contains at least two DAPs, i.e. at least one effluent which is formed at the end of step a) and which comprises a liquid phase enriched in DAP in step b).

[0126] Steps a) and b) of the method according to the invention may be carried out in one and the same individual operation or may be the subject of two different successive individual operations, the individual operation of step a) then always being carried out before the individual operation of step b).

[0127] In the embodiment presented in Figures 1 to 5, steps a) and b) are characterized in the form of separate "boxes", but they can either be carried out in the same individual operation or be the subject of two different successive individual operations. In the first case, the effluent (2) is present in the same reactor, which is for example used to carry out the two steps a) and b).

[0128] In the embodiment presented in FIG. 6, which is a preferred embodiment according to the invention, steps a) and b) are the subject of the same individual operation, which is this time characterized by the use of a single "box" (a+b).

[0129] In the embodiments shown in Figures 7 and 8, the embodiment of Figure 8 is that of a preferred embodiment according to the invention, in which steps a) and b) form the object of two distinct successive and separate operations, and which correspond to the scheme described below, in which step c) is carried out between steps a) and b).

[0130] (Solid-liquid separation step c) The process according to the invention comprises, on the one hand, reacting one or more phthalates of formula C6H4(COOC) obtained after the transesterification in step a) and / or n H 2n+12) the step of solid-liquid separation between a liquid phase containing the DAP and, on the other hand, a solid phase containing phthalate-poor, preferably phthalate-free, PVC plastic.

[0131] The physical separation of the liquid and solid phases may advantageously be carried out according to techniques known to the person skilled in the art, for example, non-exhaustively, by filtration, centrifugation, electrostatic precipitation or decantation, said techniques being used alone or in combination, in any order.

[0132] This step c) of solid-liquid separation thus makes it possible to obtain at least one solid stream (6) comprising one or more phthalate-poor PVC plastics extracted in step a), allowing to recover said reusable target PVC plastics.

[0133] The production of reusable target PVC as defined according to the present invention may require returning all or part of the solids stream (6) obtained in step c) to step a) for as many cycles as necessary to yield said target PVC plastic.

[0134] This possibility of recycling the solids stream is illustrated in Figures 2-8.

[0135] According to a first variant of the process according to the invention, said solid-liquid separation step c) is carried out after carrying out steps a) and b). This first variant is illustrated in figures 1 to 6. In this case, the liquid effluent (3) obtained from step b) is sent to a solid-liquid separation step c), leading to a separation between a liquid phase containing at least the DAP obtained after the transesterification in step b) and a solid phase containing one or more phthalate-poor PVC plastics. Advantageously, for this first variant of the process according to the invention, steps a) and b) are carried out together in the same individual operation, this particular implementation leading to a reduction in the number of individual operations required to carry out the process according to the invention, therefore limiting the number of equipment, the amount of solvent used, the energy used, etc., and therefore leading to a reduction in costs. A preferred example of implementation according to this variant is illustrated in figure 6.

[0136] According to a second variant of the process according to the invention, a solid-liquid separation step c) is carried out after carrying out step a) and before carrying out step b). This second variant is in particular illustrated in figures 7 and 8. In this case, the liquid effluent (2) obtained from step a) is sent to a solid-liquid separation step c), leading to the separation of the liquid phase containing the extracted phthalates from the solid phase containing the PVC depleted in one or more phthalates. As a result, for this second variant, steps a) and b) form the object of two distinct and separate operations. Step c) thus gives rise to a solid stream (6) comprising the PVC plastic depleted in one or more phthalates and a first liquid stream (18) containing the phthalate or phthalates extracted in step a) and which is then sent to step b) for the conversion of said phthalate or phthalates by transesterification. This second variant is particularly suitable in cases where the PVC feedstock to be treated would lead during step a) to the formation of solid phases which are unfavorable (in terms of chemical or rheological properties, etc.) for carrying out the transesterification chemistry.

[0137] For example, according to an embodiment according to this second variant of the method shown in Figures 7 and 8, where step c) is carried out between steps a) and b), steps a) and c) according to the invention may be carried out continuously in the same discontinuous reactor, this discontinuous reactor having a device for filtering the liquid effluent (2) allowing several cycles of extraction of the phthalates from the solid phase and a device for withdrawing at least the solid phase (6) allowing the final recovery of the target PVC plastic.

[0138] For another example, step c) may be carried out by centrifugation of the liquid effluent (2) or (3) comprising a liquid phase at least containing the extracted phthalates and / or DAP and the solid phase obtained from step a), leading to the separation of said solids (6) and advantageously to the return of said solids in whole or in part to step a), preferably placed in suspension beforehand, for example by feeding a solvent (9) (not shown in the figures), until the reusable target PVC plastic is produced.

[0139] (Liquid-liquid separation step d)) The process according to the invention comprises the step of obtaining from the liquid phase obtained at the end of carrying out at least steps a), b) and c) a compound of formula C6H4(COOC n H 2n+1 ) a liquid-liquid separation step d) for extracting 2 DAP.

[0140] The liquid stream ((4), (13)) containing said liquid phase is advantageously fed to this liquid-liquid separation step d), thus making it possible to obtain at least a first liquid effluent comprising DAP (stream (5) or (14) according to the diagram) and a second liquid effluent comprising at least said solvent (stream (7) or (12) according to the diagram).

[0141] The liquid-liquid separation step d) may be carried out by methods well known to the person skilled in the art, such as, non-exhaustively, distillation, decantation, evaporation, liquid-liquid extraction, etc., carried out alone or in combination. The operating conditions (temperature, pressure, etc.) of this step are determined depending on the separation method chosen.

[0142] According to one or more embodiments, the first effluent (5) consists essentially of said DAP. In this case (these cases), the second liquid effluent (7), for example shown in FIG. 1 (or alternatively in FIG. 3), consists of the remaining liquid phase after extraction of the DAP, which contains at least the solvent, by-products (BP) of ester, ether, ketal or acetal type, intermediate alkyl phthalates (IAP) and one or more phthalates, which may not be converted, extracted at the end of step a) of the process according to the invention. The second liquid effluent (7) may be returned in whole or in part, preferably in whole, to step b) of the process according to the invention.

[0143] In this case (these cases), depending inter alia on the liquid-liquid separation method chosen, for example distillation with side draw or liquid-liquid extraction, it is also possible to separate from the liquid phase not only the solvent but also the BP and, highly advantageously, the IAP, possibly with the unconverted phthalates extracted in step a). Such a separation is shown, for example, in FIG. 2 or FIG. 7 (and in FIG. 3 as an alternative to the production of stream (7)), where it can be seen that step d) gives rise to a first effluent (5) essentially consisting of said DAP, a second effluent (12) essentially consisting of the solvent, a third effluent (10) comprising the BP obtained during the transesterification in step b), and a fourth effluent (11) comprising the (IAP) and / or one or more phthalates not converted in step b) and possibly other soluble impurities. The fourth effluent (11) may advantageously be returned to step b) of the process according to the invention, in particular according to the first and second variants of the process according to the invention, in order to continue the chemical reaction leading to DAP and thus improve the yield of this product.

[0144] According to one or more alternative embodiments, as shown in Figures 4 to 6 and 8, the first liquid effluent (14) containing DAP also contains other compounds, for example one or more phthalates and / or soluble impurities (e.g. IAP) that have been partially converted in step b) and / or not (IAP). As will be explained later, according to this or these embodiments, a step of purification of DAP of the first effluent is necessary. According to this or these embodiments, the liquid-liquid separation step d) therefore advantageously gives rise to said first liquid effluent (14) of impure DAP, a second liquid effluent (12) preferably consisting essentially of said solvent, and a third effluent (10) preferably containing BP obtained during the transesterification in step b). Isolation of BP and solvent is possible, inter alia, depending on the liquid-liquid separation method chosen, for example distillation with side draw or liquid-liquid extraction. When the second liquid effluent (12) essentially consists of said solvent thus recovered, the second liquid effluent (12) may advantageously be returned partially or entirely, preferably entirely, to step a) and / or step b) of the process according to the invention, in particular according to the first and second process variants according to the invention.

[0145] (Step e) of purification of DAP (optional) The process according to the invention may comprise an optional step e) of purification of the first effluent (14) containing the DAP obtained from the liquid-liquid separation step d) to improve its quality and therefore ultimately its upgrading. The embodiments shown in Figures 4, 5, 6 and 8 show the implementation of such a purification step e).

[0146] In the case of carrying out said step e), the solvent is advantageously isolated during the implementation of step d). Furthermore, the IAP and optionally the phthalate(s) extracted at the end of step a) of the process according to the invention and not converted at the end of step b) may be isolated during step d) of the process according to the invention or alternatively during the implementation of said purification step e).

[0147] It is therefore possible to send the first effluent (14) comprising DAP, one or more phthalates partially and / or not converted in step b) and optionally soluble impurities to this purification step e) to form a liquid product (16) consisting essentially of said DAP and a liquid residue (17) comprising one or more phthalates partially and / or not converted in step b) and optionally soluble impurities.

[0148] The liquid residue (17) thus recovered may advantageously be returned to the method according to the invention, in particular to step b) of the first and second variants of the method according to the invention, as shown in FIG. 4 or FIG. 5, to continue the chemical reaction leading to DAP.

[0149] Purification step e) may advantageously be carried out via methods well known to those skilled in the art, such as precipitation, crystallization or adsorption, optionally followed by filtration or centrifugation. Purification step e) may comprise the implementation of several of these methods in parallel or successively. For example, and without being exhaustive, purification step e) may comprise a step of precipitation and filtration followed by an adsorption step, or alternatively a step of adsorption and filtration followed by an optional precipitation step, or alternatively a step of crystallization and filtration. The operating conditions (temperature, pressure, etc.) of this step e) are determined depending on the purification method chosen.

[0150] (Additional steps f1) and / or f2) (optional) of chemical transformation by transesterification) In order to facilitate the production of DAP according to the invention, apart from step b) of chemical conversion of the phthalate(s) extracted in step a), it is possible to carry out an additional chemical conversion step allowing the conversion of the IAP and / or the phthalate(s) extracted that may not have been converted at the end of step b).

[0151] The method includes, as shown in FIG. 3 or FIG. 5, converting one or more phthalates not converted in step b) and / or at least one IAP of the formula C6H4(COOC) produced in step b). n H 2n+1 The process may thus comprise an additional step f1) using a solvent for the chemical conversion of 2 by transesterification to DAP. In these embodiments, step f1) is carried out between steps c) and d), advantageously after step b), by sending the liquid phase (4), advantageously obtained at the conclusion of all steps a), b) and c), to a first additional transesterification reactor, to give a second liquid stream (13) rich in DAP, said second liquid stream (13) being sent to step d). According to this embodiment, step c) is preferably carried out at the conclusion of step b).

[0152] The process further comprises the step of converting one or more phthalates of formula C6H4(COOC) which have not been converted in step b) and / or at least one IAP which has been produced in step b) or optionally in optional step f1). n H 2n+1 )2) may comprise an additional step f2) of chemical conversion by transesterification with a solvent to DAP, which is carried out after step e) by sending the liquid residue (17) to a second additional transesterification reactor to give a third liquid stream (15) enriched in said DAP, said third liquid stream (15) being returned to step d).

[0153] The implementation of an additional step f1) and / or an additional step f2) of the chemical conversion by transesterification may be carried out according to the first variant (solid-liquid separation step c)) carried out after steps a) and b) or according to the second variant (solid-liquid separation step c)) between steps a) and b) of the process according to the invention.

[0154] Preferably, the process according to the invention comprises only one additional step of chemical conversion by transesterification, preferably step f2).

[0155] The implementation of steps f1) and / or f2) is as described for step b) of the method according to the invention. In particular, the relevant ranges of operating conditions for steps b) and f1) and / or f2) are similar, said ranges being chosen by the person skilled in the art to promote the production of DAP depending on the chemical nature of the stream to be treated at the inlet of said steps f1) and / or f2).

[0156] This also applies to the preferred use of a transesterification catalyst (8), as described in step b). The transesterification catalyst in steps f1) and / or f2) may be the same or different from that used in step b).

[0157] The stream (stream (4) or liquid residue (17)) sent to step f1) and / or step f2) is the liquid phase extracted in step a) and comprising the one or more phthalates optionally partially converted (IAP) and / or unconverted in step b), and optionally soluble impurities, which is then isolated either during the performance of liquid-liquid separation step d) of the process according to the invention or, if this is advantageously performed, during the performance of purification step e) of the process according to the invention.

[0158] Depending on the sequence of steps considered to include step f1) and / or step f2), it may be necessary to use an additional supply of solvent, which may come from a supply of "fresh" solvent (9) or else from a recycling of said solvent stream (12), possibly isolated at the end of step d) of the process according to the invention. This additional supply in the first additional transesterification reactor carried out in step f1) and / or in the second additional transesterification reactor carried out in step f2) is shown in Figures 3, 5, 6 and 8 by feeding fresh solvent (9) and / or by recycling the second effluent (12) consisting of said solvent.

[0159] If a purification step e) is performed, at least a part of said liquid residue (17) generated in step e) may be recycled to step f1) as shown in FIG. 5 to continue the chemical reaction leading to DAP.

[0160] Figures 6 and 8 respectively represent preferred embodiments according to the first variant (solid-liquid separation step c)) after carrying out steps a) and b) of the method according to the invention and according to the second variant (solid-liquid separation step c)) between steps a) and b).

[0161] As can be seen in FIG. 6, according to a preferred embodiment of the invention according to a first variant, the process comprises the implementation in one and the same separate operation of steps a) and b), a solid-liquid separation step c) after steps a) and b), a liquid-liquid separation step d), a step e) of purification of the first effluent (14) obtained in step d) comprising the DAP, and an additional step f2) of transesterification of the residue (17) advantageously obtained from step e).

[0162] According to this embodiment, as shown diagrammatically in FIG. 6, the PVC feedstock (1) in particulate form, optionally preconditioned, is introduced into a reactor which combines the implementation of steps a) and b) of a solid-liquid extraction and a chemical conversion by transesterification, respectively, preferably in the presence of a catalyst (8). The reactor produces a mixture of esters, ethers, ketals or acetals of the already defined empirical formula (C n H 2n+1 O) mA fresh solvent (9) stream external to the process is also fed, preferably consisting of, at least the chemical molecules Z, for example methyl acetate or methyl propanoate, preferably methyl propanoate, and optionally at least a portion of the solvent stream (12) isolated in the liquid-liquid separation step d). The reaction effluent (3) containing a liquid phase at least comprising DAP, preferably DMP, and a solid phase comprising phthalate-poor, preferably phthalate-free PVC plastics, is fed to a solid-liquid separation step c), for example by carrying out centrifugation to produce a solid stream (6) comprising the extracted phthalate-poor PVC plastics or phthalates, to recover the reusable target PVC plastics, and a liquid stream (4) comprising DAP, preferably at least DMP, and at least solvent. The solid stream (6) may be partially recycled to step a). The liquid stream (4) obtained from step c) containing DAP, solvent, optionally one or more phthalates not converted or partially converted (IAP) and optionally by-products (BP) is sent to a liquid-liquid separation step d), which makes it possible on the one hand to isolate the solvent as stream (12), but also preferably the BP as stream (10), and finally a liquid effluent (14) containing DAP, preferably DMP, and optionally one or more phthalates not converted and / or partially converted and optionally soluble impurities. The liquid effluent (14) is sent to a purification step e) to obtain purified DAP, preferably DMP. As the residue (17) obtained from this purification step e) may still contain one or more phthalates not converted or partially converted (IAP), an additional chemical conversion step f2) of transesterification is preferably carried out. The residue (17) is therefore advantageously sent to a second transesterification reactor containing a suitable transesterification catalyst to carry out the transesterification of the unconverted or partially converted (IAP) phthalate(s) with the solvent (9).The solvent may be a fresh solvent feed or may originate from a stream (12) that is at least partially recycled to this step f2), which gives rise to a liquid stream (15) rich in said DAP, preferably DMP, which is returned to the liquid-liquid separation step d).

[0163] According to another preferred embodiment of the invention according to a second variant, as shown in FIG. 8, the process comprises the implementation of steps a) and b) in two distinct and separate operations, step c) being carried out between steps a) and b), followed by step d), also comprising a step e) of purification of the first effluent (14) obtained in step d) containing the DAP, and an additional step f2) of transesterification of the residue (17) obtained from step e).

[0164] According to this embodiment, as shown diagrammatically in Figure 8, a PVC feedstock in particulate form (1), optionally preconditioned, is introduced into a reactor to carry out a step a) of solid-liquid extraction of one or more phthalates from said PVC feedstock. The reactor is fed with a stream of fresh solvent (9) external to the process, containing chemical molecules of the ester, ether, ketal or acetal type, for example methyl acetate or methyl propanoate, preferably methyl propanoate, and optionally a stream of solvent (12), which are isolated in a subsequent liquid-liquid separation step d). The effluent (2) resulting from step a) comprises at least a liquid phase containing at least one phthalate extracted from said feedstock (1) and at least a solid phase containing phthalate-poor, preferably phthalate-free, PVC plastic. The effluent (2) is sent to a solid-liquid separation step c), for example by carrying out a centrifugation to produce a solid stream (6) comprising the PVC plastic depleted in one or more phthalates, to recover the reusable target PVC plastic, and a liquid stream (18) containing at least one phthalate extracted in step a), and at least a solvent. The liquid stream (18) is then sent to a reactor in which a step b) of chemical conversion by transesterification of the extracted one or more phthalates is carried out, preferably in the presence of a catalyst (8). The transesterification reactor may be fed with a stream of fresh solvent (9) external to the process, containing the same chemical molecule of the ester, ether, ketal or acetal type, for example methyl acetate or methyl propanoate, preferably methyl propanoate, and optionally at least a portion of the solvent stream (12) isolated in the liquid-liquid separation step d).The reaction effluent (4) contains at least a liquid phase comprising DAP, preferably DMP, solvent, optionally unconverted or partially converted (IAP) one or more phthalates and optionally by-products (BP), which is sent to a liquid-liquid separation step d), which makes it possible to isolate on the one hand the solvent as stream (12), but also the BP as stream (10), and finally a liquid effluent (14) comprising DAP, preferably DMP and optionally partially converted (IAP) and / or unconverted one or more phthalates and optionally soluble impurities. The liquid effluent (14) is preferably sent to a purification step e) to obtain purified DAP (16), preferably DMP. Since the residue (17) obtained from this purification step e) may still contain one or more phthalates that are unconverted or partially converted (IAP), an additional transesterification chemical conversion step f2) is preferably carried out. The residue (17) is advantageously sent to a second transesterification reactor, preferably containing a suitable transesterification catalyst, to carry out the transesterification of one or more unconverted or partially converted (IAP) phthalates into esters, ethers, ketals or acetals of the already defined empirical formula (C). n H 2n+1 O) m It is carried out with a solvent (9) containing chemical molecules of Z. The solvent may be a fresh solvent feed or may originate from a stream (12) which is at least partially recycled to this step f2). This step f2) gives rise to a liquid stream (15) enriched in said DAP, preferably DMP, which is returned to the liquid-liquid separation step d).

[0165] The present invention also relates to a method for recycling PVC-based objects containing at least one phthalate, said recycling method comprising: - conditioning the PVC-based object, which at least includes grinding or shredding the PVC-based object to form a PVC feedstock in particulate form; - Recovery of DAP and recyclable target PVC plastic from said PVC feedstock in particulate form according to the invention, as described in detail above for the recovery of DAP and recyclable target PVC plastic.

[0166] The process of conditioning the PVC-based object may include the various steps detailed above for pre-conditioning the PVC feedstock before it is introduced into step a).

[0167] The present invention also relates to a method for producing flexible PVC-based objects comprising recycled PVC plastic and / or DAP obtained via the method for recovering DAP and reusable targeted PVC plastic as described in detail above.

[0168] Such manufacturing methods typically include recovering DAP and a recyclable target PVC plastic from a PVC feedstock as described above, followed by blending the recyclable target PVC plastic with additives or blending the recovered DAP with a PVC resin and then forming the blend.

[0169] (Example) Example 1 This Example 1 illustrates the present invention without limiting its scope, and in particular illustrates the extraction of phthalates contained in PVC plastics and their conversion to dimethyl phthalate by transesterification with the carboxylic acid ester chemical molecule methyl propanoate in the presence of a catalyst.

[0170] 18.2 g of PVC plastic feedstock (obtained from PVC-based objects of the "medical tubing" type) is introduced into a reactor stirred by a paddle-type mechanical stirring system. The PVC plastic feedstock is in the form of extrudates with an average size of 2 mm and contains 4.4 g of didecyl phthalate (DIDP). 17.35 g of methyl propanoate is then added, the molar ratio of methyl propanoate / DIDP being 20. 0.17 g of catalyst (NaOMe) is then added to the aforementioned mixture, the mass percentage of NaOMe / DIDP being 4%.

[0171] The reactor is sealed, purged with nitrogen, then heated to 100° C. at autogenous pressure of the order of 1.2 MPa and maintained under these conditions with stirring at 1000 rpm for 4 hours. The reactor is then cooled.

[0172] After 4 hours, the solid and liquid are obtained and analyzed.

[0173] Analysis by gas chromatography with flame ionization detection (GC-FID) of the liquid phase shows that it contains 0.13 g of dimethyl phthalate (DMP) resulting from the conversion of DIDP and 0.07 g of decylmethyl phthalate resulting from partial conversion of DIDP. Identification was made possible by comparison of the retention times of high-purity analytical standards, and quantification was carried out by determination of the response factors obtained from the analysis of these same standards.

[0174] Pre-fractionation of the resulting solid was performed by preparative size exclusion chromatography (SEC) with dual optical detection (UV / visible) and refractive index measurement (RI). Analysis of the fractions obtained from the collection was performed by high-performance liquid chromatography (HPLC) with quantitative UV-visible type optical detection. The results indicated the presence of DIDP in the target PVC plastic at a content of less than 1000 ppm, which is in compliance with current European regulations.

[0175] These results show that phthalate-free PVC according to the invention is obtained and that DIDP has been converted by 10%. This degree of conversion takes into account the total conversion of DIDP to DMP and its partial conversion. Unconverted DIDP is in the liquid phase. In this example, the extraction of DIDP and its conversion are carried out in the same process.

[0176] Example 2 This Example 2 illustrates the present invention, without limiting the scope thereof, and in particular illustrates the extraction of phthalates contained in PVC plastics and their conversion by transesterification to dimethyl phthalate with the carboxylic acid ester chemical molecule methyl acetate in the presence of a catalyst.

[0177] 13.23 g of PVC plastic feedstock (obtained from PVC-based objects of the "medical tubing" type) are introduced into a reactor stirred by a paddle-type mechanical stirring system. The PVC plastic feedstock is in the form of extrudates with an average size of 2 mm and contains 3.2 g of didecyl phthalate (DIDP). 10.61 g of methyl acetate are then added, the molar ratio of methyl acetate / DIDP being 20. 0.12 g of catalyst (NaOMe) is then added to the preceding mixture, so that the mass percentage of NaOMe / DIDP is 4%.

[0178] The reactor is sealed, purged with nitrogen and then heated to 100° C. at an autogenous pressure of the order of 1.2 MPa and maintained under these conditions with stirring at 1000 rpm for 4 hours. The reactor is then cooled.

[0179] After 4 hours, the solid and liquid are obtained and analyzed.

[0180] Analysis by gas chromatography with flame ionization detection (GC-FID) of the liquid phase shows that it contains 0.07 g of dimethyl phthalate (DMP) resulting from the conversion of DIDP and 0.17 g of decylmethyl phthalate resulting from partial conversion of DIDP. Identification was made possible by comparison of the retention times of high-purity analytical standards, and quantification was carried out by determination of the response factors obtained from the analysis of these same standards.

[0181] Pre-fractionation of the obtained solid was carried out by preparative size-exclusion chromatography (SEC) with dual optical detection (UV / visible) and refractive index measurement (RI). Analysis of the fractions obtained from the collection was carried out by high performance liquid chromatography (HPLC) with quantitative UV-visible type optical detection. The results indicated the presence of DIDP in the target PVC plastics at a content of less than 1000 ppm, which is in compliance with the current European regulations.

[0182] These results show that the present invention provides a phthalate-free PVC and that DIDP was converted by 9%. This degree of conversion takes into account the total conversion of DIDP to DMP and its partial conversion. Unconverted DIDP is in the liquid phase. In this example, the extraction of DIDP and its conversion are carried out in the same process. [Brief description of the drawings]

[0183] [Figure 1] 1 is a scheme of a method according to one embodiment of the present invention, comprising steps a), b), c) and d). [Diagram 2]FIG. 1 is a scheme of a process according to another embodiment, comprising steps a), b), c) and d), in which in step d) a separation is carried out between DAP, the solvent, the by-products obtained in step b) of type esters, ethers, ketals or acetals, and the partially converted and / or unconverted phthalates, optionally in a mixture with soluble impurities. [Diagram 3] FIG. 3 is a scheme of the process according to the embodiment illustrated in FIG. 1 or FIG. 2, comprising steps a), b), c) and d), showing the implementation of the transesterification (f1) and other optional steps of recycling the various streams. [Figure 4] FIG. 2 is a scheme of a process according to another embodiment of the present invention, comprising steps a), b), c) and d), and also comprising step e) of purification of the first effluent obtained in step d) comprising DAP. [Diagram 5] FIG. 5 is a scheme of the process according to the embodiment illustrated in FIG. 4, showing the implementation of transesterification (f1; f2) and other optional steps of recycling the various streams. [Figure 6] 1 is a scheme of a process according to a preferred embodiment of the present invention, comprising the implementation of steps a) and b) within the same separate operation (first variant of the process according to the invention), a step e) of purification of the first effluent obtained in step d) comprising DAP and an additional step f2) of transesterification of the residue obtained from step e). [Figure 7] FIG. 1 is a scheme of a method according to another embodiment of the present invention, comprising steps a), b), c) and d), steps a) and b) forming the object of two distinct and separate operations (second variant of the method according to the invention), step c) being carried out between steps a) and b). [Figure 8] FIG. 8 is a scheme of a method according to a preferred embodiment similar to that illustrated in FIG. 7, comprising a step e) of purification of the first effluent obtained in step d) comprising DAP, and an additional step f2) of transesterification of the residue obtained from step e).

Claims

1. 1. A method for recovering dialkyl phthalates and recyclable target PVC plastic from a PVC feedstock containing at least one phthalate, comprising the steps of: a) solid-liquid extraction of said PVC feedstock (1) in particulate form; said particles of PVC feedstock (1) are subjected to extraction with esters, ethers, ketals or acetals of empirical formula (C ｎ H ２ｎ＋１ O) ｍ Z is a cationically unsaturated alkyl group, and n and m are positive integers, n<4 or n>8, m is 1 or more and 3 or less, and Z is one of the following elements: R, COOR, CO, CR, CNRR', PO, P, SO, SO ２ a group selected from the list consisting of COR, and HCO, where R and R' are independently selected from linear, branched or cyclic alkyl groups, or aryl groups; producing a liquid phase rich in said phthalate and a solid phase comprising said phthalate-poor PVC plastic; b) empirical formula (C) of the ester, ether, ketal or acetal type ｎ H ２ｎ＋１ O) ｍ The liquid phase of the phthalate of formula C using the chemical molecule of Z ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ to a dialkyl phthalate by transesterification; enriching said liquid phase with said dialkyl phthalate; c) solid-liquid separation between said solid phase and said liquid phase; producing at least one solid stream (6) comprising said phthalate-lean PVC plastic and recovering said target PVC plastic; d) liquid-liquid separation of said liquid phases to produce at least a first liquid effluent ((5), (14)) comprising said dialkyl phthalate and a second liquid effluent ((7), (12)) comprising at least said solvent.

2. 2. The method of claim 1, wherein steps a) and b) are carried out in the same individual operation.

3. 2. The method according to claim 1, wherein steps a) and b) form the object of two distinct and separate operations, step a) producing a stream comprising said liquid phase and said solid phase (2).

4. 4. The method according to claim 3, further comprising carrying out a step c) between steps a) and b), wherein the stream comprising the liquid phase and the solid phase (2) obtained from step a) is sent to a solid-liquid separation step c) to obtain the stream (6) comprising the phthalate-lean PVC plastic and a first liquid stream (18) comprising the liquid phase, and wherein the first liquid stream (18) is sent to step b).

5. Additional step f １ ) and the step f １ ) is a phthalate of formula C which has not been converted and / or has been partially converted in step b). ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ to dialkyl phthalate by transesterification using the solvent (9), １ ) is carried out between steps c) and d) by sending the liquid phase obtained at the conclusion of all steps a), b) and c) to a first additional transesterification reactor, to produce a product of the formula C ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ and sending said second liquid stream (13) to step d).

6. 6. The process according to claim 5, wherein the solvent (9) is fed to a first additional transesterification reactor and / or at least a portion of the second liquid effluent ((7), (12)) obtained from step d) and comprising at least the solvent is recycled to the first additional transesterification reactor.

7. 2. The method according to claim 1, wherein in step d), the first effluent (5) consists essentially of the dialkyl phthalate.

8. 2. The process according to claim 1, wherein the liquid-liquid separation step d) results in a third effluent (10) comprising by-products of ester, ether, ketal or acetal type obtained during step b), and optionally also a fourth effluent (11) comprising the phthalates partially and / or not converted in step b) and optionally other soluble impurities, the first liquid effluent (5) consisting essentially of the dialkyl phthalates and the second liquid effluent (12) consisting essentially of the solvent.

9. The liquid-liquid separation step d) also gives rise to a third effluent (10) comprising by-products of ester, ether, ketal or acetal type obtained during step b), said first liquid effluent (14) comprising said dialkyl phthalates, phthalates partially converted and / or not converted in step b) and possibly soluble impurities, and said second liquid effluent (12) essentially consisting of said solvent, The method of claim 1, further comprising the step e) of: e) purification of said first liquid effluent (14) to produce a liquid product (16) consisting essentially of said dialkyl phthalates and a liquid residue (17) containing said phthalates partially converted and / or not converted in step b) and optionally said soluble impurities.

10. Additional step f ２ ) and the step f ２ ) is a phthalate of formula C which has not been converted and / or has been partially converted in step b). ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ to dialkyl phthalate by transesterification using the solvent (9), ２ ) is carried out after step e) by sending said liquid residue (17) to a second additional transesterification reactor to produce the product of formula C ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ and returning said third liquid stream (15) to step d).

11. 11. The process according to claim 10, wherein the solvent (9) is fed to a second additional transesterification reactor and / or at least a portion of the second liquid effluent comprising at least the solvent (12) obtained from step d) is recycled to the second additional transesterification reactor.

12. Step b) and / or additional step f) of at least a portion of said liquid residue (17) １ ) and the additional step f １ ) is a phthalate of formula C which has not been converted and / or has been partially converted in step b). ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ to dialkyl phthalate by transesterification using the solvent (9), １ ) is carried out between steps c) and d) by sending the liquid phase obtained at the end of all steps a), b) and c) to a first additional transesterification reactor, ６ H ４ (COOC ｎ H ２ｎ＋１ ) ２ and sending said second liquid stream (13) to step d).

13. 2. The process according to claim 1, wherein the second liquid effluent ((7), (12)) comprising at least the solvent (9) obtained from step d) is at least partially recycled to step a) and / or step b).

14. 2. The method according to claim 1, wherein the solids stream (6) comprising phthalate-poor PVC plastic is at least partially recycled to step a).

15. The chemical molecule of the solvent (9) has the formula (C ｎ H ２ｎ＋１ O) ｍ wherein n is n<4 or n>8, and m is 1 or more and 3 or less, and the ester is preferably an ester of the formula (C ｎ H ２ｎ＋１ O) a carboxylic acid ester of COR, ｎ H ２ｎ＋１ O) ２ CO carbonate ester of formula (C ｎ H ２ｎ＋１ O) ３ Orthoesters of CR, formula (C ｎ H ２ｎ＋１ O) an imino ester of CNRR′, ｎ H ２ｎ＋１ O) ３ P, a phosphite of the formula (C ｎ H ２ｎ＋１ O) ３ PO phosphate ester, formula (C ｎ H ２ｎ＋１ O) ２ Sulfite ester of SO, formula (C ｎ H ２ｎ＋１ O) ２ SO ２ and mixtures thereof, with the proviso that the esters contained in said mixture are selected from the list consisting of sulfate esters of the alkoxy group C ｎ H ２ｎ＋１ O, where the value of n is exactly the same, and more preferentially, the chemical molecule of the solvent (9) has the formula (C ｎ H ２ｎ＋１ 2. The process according to claim 1, wherein O) is a carboxylic acid ester of COR, where n<4 or n>8, said ester being preferably selected from the list consisting of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, nonyl acetate (which may be linear or branched), decyl acetate (which may be linear or branched), methyl propanoate, ethyl propanoate, propyl propanoate, isopropyl propanoate, nonyl propanoate (which may be linear or branched) and decyl propanoate (which may be linear or branched), preferably selected from methyl acetate or methyl propanoate.

16. The chemical molecule of the solvent (9) has the formula C ｎ H ２ｎ＋１ 2. The process according to claim 1, wherein n is an ether of formula R, where n<4 or n>8, said ether being preferably selected from the list consisting of dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dinonyl ether (which may be linear or branched), didecyl ether (which may be linear or branched) and cyclopentyl methyl ether, more preferentially selected from dimethyl ether or diethyl ether.

17. The chemical molecules of the solvent (9) each have the formula (C ｎ H ２ｎ＋１ O) ２ CRR' or (C ｎ H ２ｎ＋１ O) ２ 2. The method according to claim 1, wherein the ketal or acetal is preferably selected from the list consisting of dimethylal, 2,2-dimethoxypropane, 2,2-dimethoxybutane, diethylacetal, 2,2-diethoxypropane and 2,2-dipropoxypropane, and more preferentially from dimethylal, 2,2-dimethoxypropane and 2,2-dimethoxybutane.

18. 2. The method of claim 1, wherein the chemical molecule of the solvent (9) is methyl propanoate and the dialkyl phthalate is dimethyl phthalate.

19. In step b), optionally, step f １ ) and / or f ２ 2. The process according to claim 1, wherein the chemical transformation carried out by transesterification in the ester-exchange reaction mixture is carried out in the presence of a catalyst, preferably chosen from the list consisting of inorganic or organic, basic or acidic, Bronsted homogeneous catalysts, or Lewis acids, and heterogeneous catalysts formed by alkaline earth metal oxides, or alkali metal and / or alkaline earth metal carbonates or hydrogen carbonates, or alkali metals supported on alumina or zeolites, or zinc oxide and mixtures thereof with other oxides, or ion exchange resins.

20. The at least one phthalate of the PVC feedstock has the empirical formula C ６ H ４ (COOR １ ) (COOR ２ ) phthalates, where the ester group is in the ortho position to the benzene nucleus, R １ Or R ２ is independently selected from one member of the group consisting of a linear or branched or cyclic alkyl chain, a linear or branched alkoxyalkyl chain, or an aryl or alkylaryl chain; R １ and / or R ２ preferably contains 1 to 20 carbon atoms, or even 1 to 15 carbon atoms. The method of claim 1.

21. 2. The method of claim 1, wherein the target PVC plastic is substantially free of the phthalates, preferably containing less than 0.1% by weight total of phthalates selected from the list consisting of dibutyl phthalate, dioctyl or diethylhexyl phthalate, benzyl butyl phthalate, dibutyl phthalate, diisobutyl phthalate, dipentyl phthalate, diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, and mixtures thereof.

22. Step b), and optionally step f. １ ) and / or f ２ 2. The method according to claim 1, wherein the reaction is carried out at a temperature between room temperature and 200° C., preferably between 40° C. and 180° C., at a pressure between atmospheric pressure and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, for a period of 1 minute to 10 hours, preferably 10 minutes to 4 hours.

23. Step a) and / or step b) and optionally step f １ ) and / or f ２ 2. The method according to claim 1, wherein said first solvent (9) is added to said phthalate (A) in a molar ratio of from 2 to 250, preferably from 4 to 90, and more preferably from 1 to 20, more preferably from 1 to 20.

24. 1. A method for recycling PVC-based objects containing at least one phthalate, comprising: conditioning the PVC-based objects, which at least includes grinding or shredding the PVC-based objects to form a PVC feedstock in particulate form; - Recovery of dialkyl phthalates and recyclable target PVC plastic from said PVC feedstock in particulate form, as claimed in any one of claims 1 to 23.

25. A method for producing a flexible PVC-based object, the object comprising recycled PVC plastic and / or dialkyl phthalate, which are obtained via a method according to any one of claims 1 to 23.

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