PROCESS FOR EXTRACTION AND TRANSFORMATION BY HYDROLYSIS OF PHTHALATES CONTAINED IN PVC PLASTICS

Abstract

The present invention relates to a process for obtaining phthalic acid (PA) and a reusable PVC target plastic from a PVC feedstock containing at least one phthalate, comprising: a) a solid-liquid extraction of the PVC feedstock in contact with an organic extraction solvent, producing a liquid phase comprising said phthalate and a first solid phase comprising PVC plastic depleted in said phthalate; b) the transformation of said phthalate from a) into PA by hydrolysis; c) a solid-liquid separation between the first solid phase and the liquid phase from a) and / or b), producing a solid stream of PVC plastic depleted in said phthalate; d) a liquid-solid phase change of the PA, producing a mixed stream containing at least a second solid phase enriched in PA; e) a solid-liquid separation between the solid PA and the aqueous phase of the mixed stream, producing a solid stream of PA and an aqueous liquid effluent. Figure 1 to be published

Description

Title of the invention: METHOD FOR EXTRACTION AND TRANSFORMATION BY HYDROLYSIS OF PHTHALATES CONTAINED IN PVC PLASTICS technical field

[0001] The invention relates to the field of recycling poly(vinyl chloride) (PVC)-based plastics, in particular a process for extracting and transforming phthalates, plasticizers used in the composition of PVC, by hydrolysis. More specifically, the invention relates to a process for recovering phthalic acid (PA) and a reusable PVC target plastic from a PVC feedstock containing at least one phthalate. Previous technique

[0002] By definition, a plastic is a mixture consisting of a base polymer and numerous additives, the whole being capable of being molded or shaped (generally under heat and / or pressure) to produce a semi-finished product or an object. A commonly accepted practice is to refer to the plastic by the name of the polymer from which it is made. Thus, poly(vinyl chloride) (PVC) plastic actually corresponds to the combination of the PVC polymer, referred to hereafter as "PVC resin," with various additives chosen according to the functionalities required for the plastic. These additives can be organic molecules or macromolecules or inorganic (nano)particles and are used according to the properties they impart to the PVC resin: resistance to heat, light, or mechanical stress (stabilizers), flexibility (plasticizers), ease of processing (lubricants), coloring (dyes / pigments), etc.

[0003] Several methods of recycling PVC plastics exist: so-called conventional methods by simple mechanical recycling of plastics, methods involving modifications of their composition, or even chemical transformations of the compounds that constitute them.

[0004] Since the mid-20th century, the recycling of PVC plastic involving chemical action has been the subject of numerous studies aimed, in a first step, at solubilizing the PVC resin with a variable proportion of additives and then, in a second step, at recovering said resin by various chemical processes (precipitation, evaporation, etc.) in the presence of all or part of the soluble additives. For example, patents EP0945481, EP1268628 and EP2276801 aim to recycle, respectively, various PVC-based objects (flexible or rigid pipes, window frames, cables, etc.) and specifically PVC-based objects reinforced by fibers (tarpaulins, floor coverings, etc.) according to a process implementing a first step of dissolution in an organic solvent of the PVC resin and soluble additives, followed by a second step of precipitation with water vapor allowing the recovery of the resin and the majority of the additives.

[0005] However, retaining these additives in the PVC thus recovered for recycling is not always desirable. For example, the evolution over time of the regulations concerning them has an impact. Thus, certain plasticizers belonging to the phthalate family, widely used in the formulation of so-called "flexible" PVC some forty years ago, have been progressively subjected to authorization in Europe based on the REACH regulation, which, since the end of 2006, has aimed to ensure the safe manufacture and use of chemical substances in European industry and, ultimately, have been progressively excluded from usable additives.This is particularly the case for the following non-exhaustive list of phthalates: dibutyl phthalate (DBP), dioctyl or diethylhexyl phthalate (DOP or DEHP), benzyl butyl phthalate (BBP), diisobutyl phthalate (DIBP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, etc.

[0006] These new regulations now lead to the prohibition of the presence of such compounds in recycled raw materials (RRM). Taking into account the often very long lifespan of PVC-based objects (several decades), PVC-based objects formulated before the end of 2006 and now at the end of their life cannot be recycled via regeneration methods that result in the retention of these prohibited additives, whether these methods are conventional, such as mechanical recycling processes, or non-conventional, such as the dissolution / precipitation process examples mentioned above.

[0007] Furthermore, the phthalate plasticizers currently used in Europe (so-called REACH-compliant phthalates) and in the rest of the world represent high value-added additives that are not currently utilized when retained in recycled PVC raw material. Indeed, these are expensive products, present in significant proportions in the initial PVC formulations (several tens of percent), and do not directly impart the necessary flexibility to the recycled PVC raw material. The addition of substantial quantities of "fresh" plasticizers is therefore essential for the reuse of recycled PVC material.

[0008] The extraction of phthalate-type additives from PVC-based objects for disposal or recovery therefore represents a major challenge for optimized PVC recyclability.

[0009] Several processes involving a PVC resin dissolution step have been adapted to enable this extraction. For example, patents EP1311599 and JP2007191586 both propose a first step of dissolving the PVC resin and at least phthalate-type additives with a first organic solvent, followed a second liquid-liquid extraction step of phthalates from the previously obtained solution, using a second organic solvent different from the first. Patent JP2007092035 discloses another example of a possible implementation involving the dissolution of PVC resin and at least phthalate-type additives via the use of a solvent under supercritical conditions and the recovery of said phthalates in the same solvent after the supercritical conditions have been broken.

[0010] The removal or recovery of phthalate-type additives from PVC plastic can also be implemented without a preliminary step of dissolving said plastic, in particular via direct extraction of said phthalates from the solid polymer matrix by a suitable organic solvent, as fully documented in the publication by Ügdüler et al., 2020, “Challenge and opportunities of solvent-based additive extraction methods for plastic recycling”, Waste Management, 104, 148-182. The challenge then lies in optimizing the extraction conditions (nature of the solvent, contact time, temperature, pressure, etc.) to achieve the best possible yields of extracted phthalates.Although this methodology for removing phthalates from PVC plastics is frequently used, particularly for detecting and analytically quantifying these specific additives in said plastics, to our knowledge, no PVC-based object regeneration process uses this technique.

[0011] While critical for ensuring the efficient recycling of PVC plastics and obtaining reusable recycled PVC, the extraction of phthalate-type plasticizers is not sufficient to guarantee the economic viability of a PVC-based product regeneration process. The main reason frequently cited is the difficulty in finding an economically viable balance between the unit costs implemented in said regeneration process and the resale cost (equivalent to the added value) of the resulting products. These products consist of the naturally valuable, phthalate-free recycled PVC material and the extracted phthalates, which are of limited value. Indeed, any regeneration process that incorporates a phthalate extraction step from PVC-based products will lead to the recovery of a mixture of phthalates, which may include non-REACH-compliant phthalates.The recovery of these non-REACH compliant phthalates is of course excluded, and they must be treated as specific waste, generating additional costs. The recovery of REACH compliant phthalates, while interesting in itself, is in fact problematic because it involves technically complex and costly separation / purification steps.

[0012] In the past, some work has focused on contacting PVC plastics containing phthalates with highly concentrated basic aqueous solutions (mainly NaOH) to transform said phthalates and extract the product(s) The resulting product(s) are a salt of phthalic acid and any degradation products, depending on the associated operating conditions. This chemical reaction was carried out concurrently with, or upstream of, a PVC dechlorination step, thus yielding a non-chlorinated residue that is largely phthalate-free, enabling its energy recovery. Performing such a step upstream of dechlorination, and assisted by high frequencies or microwaves, has the advantage of recovering a usable phthalic acid salt, as reported in the following documents: patent JP3929352; the publication by F. Osada et al., 2010, "Deplasticization and dechlorination of flexible polyvinyl chloride in NaOH solution by microwave heating," J. Mater. Cycles Waste Manag., 2010, 12, 245; the publication of SM Shin et al., 2011, “Elution Behavior of Additive Agent from Flexible PVC”, Chawon Rissaikuring, 10, 6, 3.However, this implementation has the following major drawbacks: it requires the use of highly concentrated bases, it leads to the production not of phthalic acid but of its associated salt, and the extraction of phthalates is not optimized and does not comply with the REACH regulations applicable since 2006 for the recovery of a compound that can be used as a recycled raw material. Summary of the invention

[0013] The present invention aims to overcome, at least in part, the problems of the prior art, and in particular aims to provide a process for the regeneration of PVC-based objects enabling the treatment of any type of PVC filler containing phthalates and their transformation into two products of interest that can be valued as raw materials: phthalic acid and a recyclable PVC plastic free of phthalates, in particular undesirable phthalates, typically those subject to authorization by the European REACH regulation.

[0014] Phthalic acid is notably used to manufacture phthalates, which are derivatives of phthalic acid. Phthalic acid can be used as a raw material for the manufacture of other chemicals in fields other than plastic formulation, for example, to manufacture colorants, perfumes, sweeteners such as saccharin, etc.

[0015] The process according to the invention makes it possible in particular to produce a phthalic acid powder of good purity from a PVC feedstock, typically PVC waste, without stoichiometric consumption of base or acid.

[0016] Thus, in order to achieve at least one of the aforementioned objectives, among others, the present invention proposes, according to a first aspect, a process for recovering phthalic acid and a reusable target PVC plastic from a PVC feed containing at least one phthalate, comprising the following steps: a) a solid-liquid extraction of said PVC filler in the form of particles by contacting the particles of the PVC filler with at least one organic extraction solvent of said phthalate, to produce a liquid phase enriched in said phthalate and a first solid phase comprising PVC plastic depleted in said phthalate; b) a chemical transformation of said phthalate extracted in step a) into phthalic acid of formula C6H4(COOH)2 by hydrolysis with water to produce an aqueous phase comprising said phthalic acid; (c) a solid-liquid separation between said first solid phase and said liquid phase enriched in said phthalate or said aqueous phase comprising said phthalic acid to produce at least one solid stream comprising the PVC plastic depleted in said phthalate in order to recover the target PVC plastic; d) a phase change of phthalic acid from the dissolved state in said aqueous phase to a solid state to produce a mixed stream comprising an aqueous liquid phase depleted in phthalic acid and a second solid phase enriched in phthalic acid; e) a solid-liquid separation between the phthalic acid in the solid state from step d) and the aqueous liquid phase of said mixed stream, to produce a solid stream of phthalic acid and a liquid effluent comprising residual water from step b).

[0017] One advantage of the present invention lies in the process's ability, through a compatible solid-liquid extraction step combined with a chemical hydrolysis reaction, to extract and transform a mixture of phthalates initially trapped in polymeric matrices of various PVC-based plastic objects, regardless of the composition of said mixture (i.e., regardless of the nature and origin of the different phthalates) and despite the possible presence of numerous other additives, into a single REACH-compliant and usable phthalate product: phthalic acid. Furthermore, obtaining phthalic acid from the phthalate mixture makes it possible to consider transforming said phthalic acid into new and multiple phthalates, which are still widely used in many fields such as the plastics industry, according to a circular economy principle.

[0018] According to a first variant, steps a) and b) are carried out within the same unit operation, producing a stream comprising at least the aqueous phase comprising phthalic acid and the first solid phase comprising PVC plastic depleted in said phthalate.

[0019] According to a second alternative to the first variant, steps a) and b) are carried out as two separate unit operations, step a) producing a stream comprising the liquid phase enriched in said phthalate and said first solid phase sent to step c) carried out between steps a) and b), step c) producing the stream comprising the PVC plastic depleted in said phthalate and a first liquid stream comprising the liquid phase enriched in said phthalate.

[0020] According to this second variant, the process preferably includes a step g) of removing at least part of the organic extraction solvent from the first liquid stream prior to step b), to produce a first concentrated liquid stream comprising said phthalate sent to step b).

[0021] According to one or more embodiments, step g) of removing at least part of the organic extraction solvent from the first liquid stream includes evaporation of the extraction solvent, preferably using a succession of expansion flasks.

[0022] According to one or more embodiments, the organic extraction solvent recovered in step g) is recycled at least in part in step a).

[0023] According to one or more embodiments, the solid stream comprising the phthalate-depleted PVC plastic separated in step c) is recycled at least in part in step a).

[0024] According to one or more embodiments, the organic extraction solvent is chosen from the list consisting of ketones, ethers, glycol ethers, cyclic and aromatic hydrocarbons, short-chain aliphatic alcohols, linear or branched, of molecular formula CnH2n+iOH with n < 4, n being a non-zero natural number, and mixtures thereof.

[0025] According to one or more embodiments, the organic extraction solvent is chosen from the list consisting of methyl ethyl ketone, diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, acetophenone, tetrahydrofuran, cyclohexane, xylenes, toluene, methanol, ethanol, n-propanol, z-propanol, and mixtures thereof, and preferably is chosen from said alcohols, ketone / alcohol mixtures, hydrocarbon / alcohol mixtures, cyclohexane, toluene, xylenes, methoxycyclopentane, methyl isobutyl ketone, cyclopentanone, acetophenone, and preferably said organic extraction solvent is toluene, methyl ethyl ketone, acetophenone or a methyl ethyl ketone / methanol mixture.

[0026] According to one or more embodiments, the hydrolysis in step b) is carried out in the presence of an acid hydrolysis catalyst, preferably a homogeneous acid catalyst selected from the list consisting of mineral Brønsted acid catalysts, preferably hydrochloric acid, sulfuric acid, phosphoric acid, organic Brønsted acid catalysts, preferably p-toluenesulfonic acid, and Lewis acid catalysts, preferably A1F3, or a heterogeneous acid catalyst selected from the list consisting of aluminas, chlorinated aluminas, fluorinated aluminas, mesoporous aluminosilicates, zeolites and mixtures thereof with other oxides, ion exchange resins (H+), preferably sulfonic resins.

[0027] According to one or more embodiments, the hydrolysis in step b) is carried out at a temperature between ambient temperature and 150°C, preferably between 40°C and 130°C, at a pressure between atmospheric pressure and 5.0 MPa, preferably between atmospheric pressure and 2.0 MPa, and for a duration between 1 minute and 10 hours, preferably between 10 minutes and 4 hours.

[0028] According to one or more embodiments, the hydrolysis in step b) is carried out so that the molar ratio between the amount of water and the amount of said phthalate extracted in step a) is between 100 and 9000.

[0029] According to one or more embodiments, step d) includes at least one phthalic acid precipitation step, preferably comprising cooling to a temperature between 10°C and ambient temperature.

[0030] According to one or more embodiments, said at least one phthalate of said PVC filler is a phthalate of molecular formula C6H4(COORi)(COOR2) whose ester groups are in the ortho position of the benzene ring, Ri or R2 being chosen independently from one of the elements of the group consisting of an alkyl chain, linear or branched or cyclic, an alkoxyalkyl chain, linear or branched, or an aryl or alkylaryl chain, Ri and / or R2 preferably comprising between 1 and 20 carbon atoms, or even between 1 and 15 carbon atoms.

[0031] According to one or more embodiments, the target PVC plastic is free of said phthalate, and preferably comprises less than 0.1% by mass in total of phthalates selected from the list consisting of dibutyl phthalate, dioctyl or diethylhexyl phthalate, benzyl butyl phthalate, dibutyl phthalate, dii-sobutyl phthalate, dipentyl phthalate, diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, and mixtures thereof.

[0032] According to one or more embodiments, the process includes an additional separation step f) directly upstream of step d) or downstream of step e) to separate at least one aqueous liquid phase from other compounds in liquid or gas phase. When some of said compounds include extraction solvent or phthalate extracted in step a) and not converted and / or partially converted in step b) or water, they are preferably recycled: the extraction solvent can be recycled in step a), and the water and / or phthalate extracted in step a) and not converted and / or partially converted in step b) can be recycled in step b).

[0033] According to a second aspect, the present invention relates to a method for recycling a PVC-based object containing at least one phthalate comprising: - the packaging of said PVC-based object comprising at least one grinding or shredding of said PVC-based object to form a PVC charge in the form of particles; - the recovery of phthalic acid and a reusable target PVC plastic from said PVC feed in the form of particles according to the first aspect of the invention.

[0034] The present invention also relates, according to a third aspect, to a method of manufacturing an object based on flexible PVC comprising recycled PVC plastic and / or a phthalate made from phthalic acid recovered by the process according to the first aspect of the invention.

[0035] Other objects and advantages of the invention will become apparent from the following description, particular embodiments of the invention given by way of non-limiting examples, the description being made with reference to the attached figures described below. List of figures

[0036] [Fig.1]

[0037] Figure 1 is a diagram of the process according to an embodiment of the invention comprising steps a), b), c), d), and e), the optional step g) of removing the extraction solvent, and the optional separation step f), and wherein the extraction steps a) and hydrolysis steps b) are carried out as two separate unit operations, with the solid-liquid separation step c) performed between steps a) and b) (second variant of the process according to the invention). The organic extraction solvent (7) is miscible with water.

[0038] [Fig.2]

[0039] Figure 2 is a diagram of the process according to another embodiment, comprising, as in the embodiment illustrated in Figure 1, separate extraction steps a) and hydrolysis steps b), with an intermediate solid-liquid separation step c), and further comprising the optional step g), and optional separation steps f3) and f2) respectively directly upstream of step d) and downstream of step e). The organic extraction solvent (7) is miscible with water.

[0040] [Fig.3]

[0041] Figure 3 is a schematic diagram of the process according to another preferred embodiment, comprising, as in the embodiments illustrated in Figures 1 and 2, separate extraction steps a) and hydrolysis steps b), with an intermediate solid-liquid separation step c), and further comprising the optional step g), and an optional separation step f4) directly upstream of step d) as well as an optional separation step f5) downstream of step f4). The organic extraction solvent (7) is immiscible with water.

[0042] [Fig.4]

[0043] Figure 4 is a diagram of the process according to another embodiment of the invention comprising steps a), b), c), d) and e), and the optional separation step fl), and wherein the extraction steps a) and hydrolysis steps b) are carried out within a single unit operation (first variant of the process according to the invention). The organic extraction solvent (7) is miscible with water.

[0044] [Fig.5]

[0045] [Fig.5] is a diagram of the process according to another embodiment, comprising, as in the embodiment illustrated in [Fig.4], concomitant extraction steps a) and hydrolysis b), with a solid-liquid separation step c) directly downstream, and further comprising the optional separation steps f3) and f2) respectively directly upstream of step d) and downstream of step e). The organic extraction solvent (7) is miscible with water.

[0046] [Fig.6]

[0047] Figure 6 is a diagram of the process according to another embodiment, comprising, as in the embodiments illustrated in Figures 4 and 5, concomitant extraction steps a) and hydrolysis steps b), with a solid-liquid separation step c) directly downstream, and further comprising the optional separation step f4) directly upstream of step d) as well as an optional separation step f5) downstream of step f4). The organic extraction solvent (7) is immiscible with water.

[0048] In the figures, the same references designate identical or analogous elements. Description of implementation methods Terminology

[0049] Some definitions are given below, although more details on the objects defined below may be given later in the description.

[0050] A PVC-based object is understood to be an object, generally a consumer product, which comprises, and preferably is made of, at least one PVC plastic.

[0051] Poly(vinyl chloride) plastic, also called PVC plastic or simply PVC, is understood to mean the combination of a PVC polymer, also called PVC resin, with various additives chosen according to the functionalities required for the PVC plastic, themselves chosen according to the applications intended.

[0052] Said PVC polymer is derived from the radical polymerization of vinyl chloride (VCM), a monomer itself obtained from chlorine and ethylene. Depending on the implementation of said polymerization, four families of PVC resins can be used: 1) suspension PVC resins or PVC-S (suspension polymerization of VCM), 2) emulsion PVC resins or PVC "pastes" (emulsion polymerization), 3) bulk PVC resins or PVC-M (bulk polymerization) and 4) superchlorinated PVC resins or PVC-C, obtained by superchlorination in post-treatment of the preceding resins.

[0053] Said additives entering into the composition of a PVC plastic can be organic molecules or macromolecules or inorganic (nano)particles and are used according to the properties they give to the PVC resin: resistance to heat, light or mechanical stress (stabilizers), flexibility (plasticizers), ease of implementation (lubricants), coloring (colorants / pigments), etc.

[0054] Phthalates are understood to be the group of chemical products formed by the carboxylic diesters of phthalic acid. They are composed of a benzene ring and two carboxylic ester groups positioned ortho to the benzene ring. They can be described using the following formula:

[0055] [Chem.l]

[0056] or by the molecular formula C6H4(COORi)(COOR2), where Ri and R2 are independently selected from one of the elements of the group consisting of an alkyl chain, linear, branched or cyclic, an alkoxyalkyl chain, linear or branched, or an aryl or alkylaryl chain, said alkyl, alkoxyalkyl, aryl or alkylaryl chain typically comprising between 1 and 20 carbon atoms, or even between 1 and 15 carbon atoms. For example, Ri and / or R2 may be independently selected from the ethyl, n-butyl, isobutyl, n-pentyl, iso-pentyl, n-hexyl, n-octyl, n-nonyl, isononyl, n-decyl, isodecyl, methoxyethyl, benzyl groups. Phthalates are commonly used as plasticizers in plastics and in particular as plasticizers in PVC-type plastics, notably to make them flexible.

[0057] In the present description, the term "phthalic acid" (PA), also known as benzene-1,2-dicarboxylic acid or o-phthalic acid, refers to the product of molecular formula C6H4(COOH)2 resulting from the hydrolysis reaction of at least one phthalate-type plasticizer (and in particular of molecular formula C6H4(COORi)(COOR2), as described above) present in PVC-based articles with water (H2O).

[0058] The term "alcohol-type by-product(s)" (AL) means the by-product(s) of formula RiOH or R2OH resulting from the hydrolysis reaction of at least one phthalate-type plasticizer present in PVC-based articles with H2O. Ri or R2 are defined identically to Ri and R2 of phthalates.

[0059] The term "alkyl phthalate intermediate" (API) or "partially converted phthalate" means the by-product with the molecular formula C6H4(COOH)(COOR1) or C6H4(COOR2)(COOH) resulting from the incomplete hydrolysis reaction of at least one plasticizer of phthalate type (and in particular of molecular formula C6H4(COORi)(COOR2), as described above) present in PVC-based objects with H2O. Ri or R2 are defined identically to Ri and R2 of phthalates.

[0060] The term "reusable target PVC plastic" means "phthalate-free PVC", that is to say, the solid comprising at least the PVC resin with the addition of at least one of the additives initially present in the PVC plastic of the PVC feed treated according to the invention, and from which the phthalates have been extracted and transformed according to the invention into phthalic acid in whole or in part.The terms "phthalate-free" mean in particular that the solid PVC obtained as a product of the process according to the invention contains, in total, less than 0.1% by mass of phthalates subject to authorization by the REACH regulation in Europe (Annex XIV of Regulation (EC) No 1907 / 2006 of the European Parliament and of the Council of 18 December 2006), in particular less than 0.1% by mass of phthalates selected from the list consisting of the following phthalates: dibutyl phthalate (DBP), dioctyl or diethylhexyl phthalate (DOP or DEHP), benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), dipentyl phthalate (DPP), diisopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, alone or in mixtures.

[0061] In the present description, the expression "greater than..." is understood as strictly greater than, and symbolized by the sign ">", and the expression "less than" as strictly less than, and symbolized by the sign "<".

[0062] In this description, ambient temperature (Tamb) is typically understood to mean 20°C ± 5°C, and atmospheric pressure means 0.101325 MPa.

[0063] In this description, the term "include" is synonymous with (means the same as) "comprise", "include", and "contain", and is inclusive or open and does not exclude other elements not mentioned. It is understood that the term "include" includes the exclusive and closed term "consist".

[0064] In this description, the expression "between ... and ..." means that the limit values ​​of the interval are included in the range of values ​​described, unless otherwise specified.

[0065] In this description, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in this description, a preferred pressure range can be combined with a more preferred temperature range.

[0066] In the following, particular embodiments of the invention may be described. They may be implemented separately or in combination with each other, without limitation. mitation of combinations when technically feasible.

[0067] The description of the process according to the first aspect of the invention below refers to the diagrams in Figures 1 to 6, illustrating different implementations of the process according to the invention.

[0068] According to the invention, the process for recovering AP and a reusable target PVC plastic from a PVC feedstock containing at least one phthalate comprises, and may consist of, the following steps: a) a solid-liquid extraction of said PVC filler in the form of particles 1 by contacting the particles of the PVC filler with at least one organic extraction solvent 7 of said phthalate, to produce a liquid phase enriched in said phthalate and a first solid phase comprising PVC plastic depleted in said phthalate; b) a chemical transformation of said phthalate extracted in step a) into phthalic acid of formula C6H4(COOH)2 by hydrolysis with water 9 to produce an aqueous phase comprising said phthalic acid; (c) a solid-liquid separation between said first solid phase and said liquid phase enriched in said phthalate or said aqueous phase comprising said phthalic acid to produce at least one solid stream comprising the PVC plastic depleted in said phthalate 8 in order to recover the target PVC plastic; d) a phase change of phthalic acid from the dissolved state in the aqueous phase to a solid state to produce a mixed stream comprising an aqueous liquid phase depleted in phthalic acid and a second solid phase enriched in phthalic acid (5, 19, 22);

[0069] e) a solid-liquid separation between the phthalic acid in the solid state from step d) and the aqueous liquid phase of said mixed stream, to produce at least one solid stream of phthalic acid 6 and a liquid effluent (11, 14, 20) comprising residual water from step b). Charge

[0070] The process according to the invention is fed by a charge called "PVC charge" 1 comprising at least one PVC plastic, which necessarily comprises at least one phthalate as described in the present invention.

[0071] The PVC plastic may contain at least 0.1% by mass of phthalates, or even at least 1% by mass of phthalates or at least 5% by mass of phthalates. In general, PVC plastics advantageously comprise less than 60% by mass of phthalates, typically less than 40% by mass of phthalates.

[0072] Said PVC filler is advantageously a PVC filler to be recycled of the "production scraps" type, i.e. waste from the production processes of the PVC polymer during its polymerization or of the PVC plastic during its formulation / shaping or of the PVC-based object during its production, or of the "post-consumer waste" type, i.e. waste generated after consumption by the user of said PVC-based object.

[0073] In particular, the PVC load to be recycled may come from any collection and sorting channel or existing network for production scraps and / or post-consumer waste allowing the isolation of a stream based on at least one PVC plastic containing at least one phthalate, including collection and sorting channels or networks specific to plastic waste.

[0074] Thus, the PVC material, which is typically of the "production offcuts" and / or "post-consumer waste" type, generally originates from the major application areas that use PVC plastic, such as, but not limited to, the building and construction, packaging, automotive, electrical and electronic equipment, sports, and medical equipment sectors. Preferably, the PVC material originates from the building and construction sector. More specifically, PVC-based products are generally used in these sectors as profiles (windows, doors, blinds, roller shutter boxes), pipes and fittings, various rigid products and bottles, rigid sheets and films, flexible films and sheets, flexible tubes and profiles, cables, floor coverings, coated fabrics, etc.Preferably, PVC-based articles forming the PVC filler include at least so-called flexible PVC, i.e. PVC containing plasticizer-type additives, preferably of the phthalate type, as is the case for example for the following PVC-based articles: flexible films and sheets, flexible tubes and profiles, cables, floor coverings, coated fabrics, etc.

[0075] Advantageously, the PVC filler comprises at least 50% by mass, preferably at least 70% by mass, preferably at least 90% by mass and even more preferably at least 95% by mass of PVC plastic comprising at least one phthalate.

[0076] Preferably, the PVC filler comprises so-called flexible PVC, i.e. PVC containing plasticizer-type additives, preferably of the phthalate type.

[0077] Even more preferably, the PVC filler comprises mainly, or even exclusively, so-called flexible PVC, that is to say PVC containing plasticizer-type additives, preferably of the phthalate type.

[0078] The PVC feed processed in the recovery process of a DAP and a reusable target PVC plastic according to the invention is in the form of particles. Thus, if the PVC feed is in an initial form, such as that of production scrap or post-consumer waste, particularly in the latter case in the initial form of PVC-based objects, it may first undergo a conditioning step comprising at least one grinding or shredding step to form a PVC feed. in particle form. Depending on the sectors and / or networks from which these production offcuts and / or end-of-life PVC-based objects originate, the PVC waste can be shredded and / or washed and / or undergo any other conditioning step as described below, in order to form the PVC feed in the form of particles suitable for the process according to the invention. For example, the PVC feed can advantageously be in the form of shredded material, possibly washed, with a largest dimension of less than 20 cm, preferably less than 10 cm, preferably less than 1 cm, and even more preferably less than 5 mm. The PVC feed can also advantageously be in the form of micronized solids, that is to say, in the form of particles preferably having an average size of less than 1 mm, for example, between 10 micrometers (µm) and 800 micrometers (µm).The average size corresponds advantageously to the average diameter of the spheres circumscribed about said particles.

[0079] Thus, by PVC charge in the form of particles, we mean PVC plastic particles typically having an average size, as defined above, of between 10 pm and 20 cm, for example ground-type particles having an average size of between 1 mm and 20 cm, preferably between 1 mm and 10 cm, more preferably between 1 mm and 1 cm, even more preferably between 1 mm and 5 mm, or particles resulting from micronization (very fine grinding to produce a powder) of an average size of less than 1 mm, preferably between 10 pm and 800 pm. Preferably, the PVC feed treated in the process according to the invention is in the form of ground-type particles, preferably particles with an average size between 1 mm and 5 mm, or particles resulting from micronization (very fine grinding to produce a powder) with an average size of less than 1 mm.

[0080] The PVC filler may also include "macroscopic" impurities, such as glass, metal, plastics other than PVC (e.g., PET, etc.), wood, paper, cardboard, mineral elements, etc. Advantageously, the PVC filler comprises at most 50% by mass, preferably at most 30% by mass, preferably at most 10% by mass, and even more preferably at most 5% by mass of "macroscopic" impurities.

[0081] The different steps of the process according to the invention leading to the AP and the reusable target PVC plastic are detailed in the following paragraphs.

[0082] Optional preliminary step of conditioning the PVC load

[0083] According to the invention, the method may include a preliminary conditioning step operation of the PVC feed (not shown in the figures) comprising at least one step of grinding or shredding the PVC feed to form a PVC feed in the form of solid particles as defined above, suitable for being sent to step a) solid-liquid extraction. This preliminary conditioning step may also include one or more steps mentioned in the following non-exhaustive list: micronization grinding, sorting, further sorting, washing, drying, etc. Depending on the nature of the PVC feed being processed, the step(s), as well as their frequency and possible sequences, involved in the preliminary conditioning step are chosen by those skilled in the art to limit the quantity of macroscopic impurities and reduce the size of the solid elements initially composing the PVC feed. For example, the preliminary conditioning step allows for the supply of PVC feedstock in the form of particles, such as washed, ground material, with an average size of less than 5 mm, and a macroscopic impurity content preferably not exceeding 10% by mass, and more preferably not exceeding 5% by mass. This pre-conditioned PVC feedstock can also be in the form of micronized solid particles, i.e., particles with an average size of less than 1 mm, for example, between 10 µm and 800 µm.

[0084] Step a) of solid-liquid extraction of phthalates

[0085] The process according to the invention comprises a step a) of solid-liquid extraction of the phthalate(s) from the PVC feed in the form of particles 1 by contacting said feed with an organic extraction solvent 7, in order to obtain an effluent comprising at least a liquid phase and a first solid phase. Said liquid phase is then enriched in said phthalate(s), and the first solid phase comprises PVC plastic depleted in said phthalate(s). The effluent is represented by the stream 2 in Figures 1 to 3, where steps a) and b) are carried out separately.

[0086] Said organic extraction solvent 7 is thus chosen for its physicochemical properties and its ability to penetrate the polymeric matrix while drastically limiting its dissolution, in order to efficiently extract the phthalate(s) from the PVC filler in particulate form. In this regard, a person skilled in the art can rely on knowledge of the Hildebrand and / or Hansen solubility parameters of solvents to define, with respect to these same parameters specific to PVC resins and phthalates, the most suitable solvent for carrying out step a) of solid-liquid extraction of the process according to the invention. Said extraction solvent is also chosen so as to allow the performance of step b) of chemical transformation of said phthalate(s) by hydrolysis, while limiting secondary chemical reactions and simplifying and streamlining the subsequent separation step(s) necessary to obtain the PA according to the invention.

[0087] According to one or more embodiments, said extraction solvent is advantageously an organic solvent or a mixture of organic solvents, chosen(s) among : - ketones, such as methyl ethyl ketone (MEK), diethyl ketone (DEK), 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone (MIBK), cyclic ketones such as cyclopentanone, cyclohexanone, aromatic ketones such as acetophenone, - Ethers such as methoxycyclopentane (CPME), cyclic ethers such as tetrahydrofuran (THF), glycol ethers such as 2-methoxyethanol, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, - cyclic and aromatic hydrocarbons such as cyclohexane, xylenes, toluene, - alcohols with a short, linear or branched aliphatic chain, with the molecular formula CnH2n+i OH with n < 4, n being a non-zero natural number, such as methanol, ethanol, n-propanol, z-propanol.

[0088] Preferably, the organic extraction solvent is chosen from the aforementioned alcohols, in particular methanol, ethanol, n-propanol, z-propanol, the aforementioned ketone / alcohol mixtures, the aforementioned hydrocarbon / alcohol mixtures, cyclohexane, toluene, xylenes, CPME, MEK, MIBK, cyclopentanone, taken alone or in mixture, and more preferably chosen from the aforementioned alcohols, the aforementioned ketone / alcohol mixtures, the aforementioned hydrocarbon / alcohol mixtures, cyclohexane, toluene, xylenes, acetophenone, MEK, MIBK, cyclopentanone, taken alone or in mixture.

[0089] The extraction solvent may advantageously be toluene, MEK, acetophenone, or a mixture of MEK / methanol.

[0090] The solid-liquid extraction step a) of the phthalate(s) from the PVC 1 feed is preferably carried out under the following operating conditions: a temperature between ambient temperature and 200°C, preferably between 40°C and 180°C, more preferably between 60°C and 150°C, and even more preferably between 60°C and 145°C, a pressure between atmospheric pressure and 11.0 MPa, preferably between atmospheric pressure and 5.0 MPa, more preferably between atmospheric pressure and 2.0 MPa, a residence time between 1 min and 10 h, preferably between 5 min and 4 h, more preferably between 5 min and 2 h and even more preferably between 10 min and 30 min.

[0091] Preferably, step a) is carried out so that the molar ratio between the quantity of solvent 7 and the quantity of the phthalate(s) to be extracted from the PVC charge 1 is between 2 and 250, preferably between 4 and 100, and even more preferably between 4 and 30.

[0092] The reactor used in step a) of the process according to the invention can advantageously be a type reactor stirred by a mechanical stirring system and / or by recirculation loop and / or by fluidization, and / or by ultrasound, for example a discontinuous (also called "batch") or continuous type reactor, preferably perfectly stirred, or a rotary drum type reactor.

[0093] In terms of implementation, the PVC charge in the form of particles 1 and the organic extraction solvent 7 are advantageously mixed. According to a first option, the mixture can be prepared prior to the introduction of the PVC feedstock and the extraction solvent into the reactor in step a) of solid-liquid extraction. In this case, the mixture can be formed in a mixer and then introduced into the reactor, which is maintained at the desired pressure and temperature. According to a second option, the PVC feed in the form of particles 1 and the solvent 7 can be introduced separately into the reactor of step a) of the process according to the invention. The solid PVC feed and the solvent are then preferably injected into the reactor via two separate lines, one for injecting the extraction solvent 7, and the other for injecting the solid PVC feed in the form of particles 1. In this case, the mixture of the PVC feed and the solvent is formed directly within the reactor.

[0094] According to the invention, said solid-liquid extraction step a) allows obtaining at least one effluent comprising at least one liquid phase containing at least the extracted phthalates and at least one first solid phase containing the phthalate-depleted PVC plastic, preferably phthalate-free.

[0095] Under the operating conditions of this step, the extracted phthalate(s) are advantageously in liquid form.

[0096] Step b) of chemical transformation of said phthalates by hydrolysis

[0097] The process according to the invention includes a step b) of chemical transformation of the phthalate(s) extracted in step a) into at least phthalic acid of formula C6H4 (COOH)2 by hydrolysis reaction, preferably in liquid phase, between said phthalate(s) extracted in step a) and water (H2O).

[0098] Step b) of hydrolysis of the phthalate(s) present to form phthalic acid is preferably carried out under the following operating conditions: a temperature between ambient temperature and 150°C, preferably between ambient temperature and 145°C, more preferably between 40°C and 130°C, and more preferably between 60°C and 110°C, a pressure between atmospheric pressure and 5.0 MPa, preferably between atmospheric pressure and 2.0 MPa, more preferably between atmospheric pressure and 0.5 MPa, a residence time between 1 min and 10 h, preferably between 10 min and 4 h, more preferably between 10 min and 2 h and even more preferably between 10 min and 1 h.

[0099] Water 9 is therefore introduced at this step b) of the process, to carry out the hydrolysis reactions of the phthalate(s) in order to form phthalic acid.

[0100] Preferably, step b) is carried out so that the molar ratio between the quantity of water 9 and the quantity of phthalates to be transformed from the liquid phase containing the phthalate(s) extracted at the end of step a) is between 100 and 9000, preferably between 150 and 1800 and even more preferably between 200 and 850.

[0101] Preferably, said hydrolysis step b) is carried out in the presence of a hydrolysis catalyst 10, advantageously introduced into the reaction medium. The hydrolysis catalyst 10 thus used is advantageously an acid catalyst, for example chosen from the acid catalysts in the following non-exhaustive list, well known to those skilled in the art, and preferably from the list consisting of:

[0102] - homogeneous catalysts such as mineral Brønsted acid catalysts (e.g. hydrochloric, sulfuric, phosphoric acids, etc.), organic Brønsted acid catalysts (e.g. methanesulfonic, trifluoromethanesulfonic, trifluoroacetic, p-toluenesulfonic acids, etc.), and Lewis acid catalysts (e.g. A1F3); - acidic heterogeneous catalysts such as aluminas, chlorinated or fluorinated aluminas, mesoporous aluminosilicates, zeolites and their mixtures with other oxides, ion exchange resins (H+), such as sulfonic resins, etc.

[0103] For example, the catalyst used according to the invention is a homogeneous catalyst, in particular a homogeneous catalyst of the organic Brønsted acid catalyst type such as p-toluenesulfonic acid.

[0104] Preferably, the quantity of catalyst introduced is such that the mass ratio between the catalyst and the phthalate(s) to be transformed is between 0.02% and 10% by mass, preferably between 0.5% and 8% by mass and even more preferably between 1% and 5% by mass.

[0105] The catalyst, whether homogeneous or heterogeneous, can be recycled and / or removed from the process according to methods well known to those skilled in the art, and is preferably recycled. It can be isolated, for removal or preferably recycled for the hydrolysis reaction, in the downstream steps of the process or in any other dedicated step.

[0106] The reactor implemented in step b) may advantageously be a type of reactor stirred by a mechanical stirring system and / or by recirculation loop and / or by fluidization, and / or by ultrasound, for example a batch or continuous type reactor, preferably perfectly stirred, or a rotary drum type reactor.

[0107] According to the invention, said step b) of phthalate transformation allows obtaining an effluent (flow 4 in figures 1 to 3 or flow 24 in figures 4 to 6) comprising at least one aqueous phase containing at least the phthalic acid obtained after hydrolysis reaction of the phthalates extracted in step a), initially contained in the liquid phase formed in step a).

[0108] Steps a) and b) of the process according to the invention may be carried out in a single unit operation upstream of step c) of solid-liquid separation of the process according to the invention, as shown in Figures 3 to 6, or may be carried out as two separate unit operations separated by at least said step c), the unit operation of step a) then always being carried out prior to the unit operation of step b), as shown in Figures 1 to 3, and explained in more detail below. Step c) of solid-liquid separation

[0109] The process according to the invention comprises a step c) of solid-liquid separation between on the one hand the first solid phase containing the phthalate-depleted PVC plastic, preferably phthalate-free, and on the other hand the liquid phase containing the phthalate(s) extracted in step a) or the aqueous phase comprising the phthalic acid obtained in step b), according to the first and second variants of the process described in detail below, and depending on the position of step c) relative to steps a) and b).

[0110] The physical separation of the liquid and solid phases can advantageously be carried out according to techniques known to the person skilled in the art such as, but not limited to, filtration, centrifugation, for example the use of hydrocyclones, electrostatic precipitation, or decantation, said techniques being used alone or in combination, in any order.

[0111] This solid-liquid separation step c) therefore makes it possible to produce at least one solid stream 8 comprising the PVC plastic depleted in the phthalate(s) extracted in step a), in order to recover said reusable target PVC plastic.

[0112] Obtaining the reusable target PVC as defined according to the invention may require returning all or part of the solid stream 8 obtained in step c) to step a), in as many cycles as necessary to produce said target PVC plastic. This possibility of recycling the solid stream is shown in figures 1 to 6.

[0113] For example, step c) can be carried out by centrifuging the liquid effluent 2 comprising the liquid phase from step a) containing at least the extracted phthalates and the first solid phase, leading to the separation of said solid 8, and advantageously to the return of all or part of said solid to step a), preferably previously put into suspension, for example by means of a supplement of extraction solvent 7 (not shown in the figures), until the reusable target PVC plastic is produced.

[0114] According to a first embodiment of the process according to the invention, step c) of solid-liquid separation occurs after step a) and before step b). This first embodiment is illustrated in particular in Figures 1 to 3. In this In this case, the liquid effluent 2 from step a) is sent to solid-liquid separation step c), which leads to the separation of the liquid phase containing the extracted phthalates from the first solid phase containing the phthalate-depleted PVC. Step c) thus produces the solid stream 8 containing the phthalate-depleted PVC plastic, and a first liquid stream 3 containing the phthalate(s) extracted in step a) which is then sent to step b) for the transformation of said phthalate(s) by hydrolysis, or to the optional step g) described later in the present invention, allowing for the total or partial removal of the extraction solvent before sending the phthalates to be transformed to step b). This first variant is particularly suitable for cases where the PVC load to be treated would lead to the formation, during step a), of a solid phase unfavorable to carrying out the chemical hydrolysis reaction (in terms of chemical or rheological properties, etc.).A preferred example of implementation according to this variant is illustrated in [Fig.3].

[0115] According to a second embodiment of the process according to the invention, the solid-liquid separation step (c) occurs after steps (a) and (b), which are carried out in a single unit operation. This second embodiment is illustrated in particular in Figures 4 to 6. In this case, the liquid stream 24, from the concurrent steps (a) and (c), is sent to the solid-liquid separation step (c), which leads to the separation between at least the aqueous phase containing at least the AP obtained after the hydrolysis reaction in step (b), and the first solid phase containing the phthalate-depleted PVC plastic. The liquid phase (aqueous and organic) and the first solid phase containing the phthalate-depleted PVC plastic are separated at the end of this step (c).The simultaneous (joint) implementation of steps a) and b) within a single unit operation leads to a reduction in the number of unit operations required to carry out the process according to the invention, and therefore to a limitation on the number of pieces of equipment, the energy used, etc., and thus to a decrease in costs. A preferred example of this variant is illustrated in [Fig. 5], where the simultaneous implementation of steps a) and b) is represented by the use of a single step (a+b) (a single "box" (a+b) is shown). In this case, the presence of water 9 during the extraction phase can advantageously modify the extraction properties of the solvent 7 compared to those it would have had if used alone.For example, the combination of extraction solvent 7 and water 9 can allow the use of an extraction solvent 7 initially suitable for the extraction of phthalates but having too high a solubilizing power of PVC resin, which is thus counterbalanced by the presence of water, the mixture ultimately having a lower solubilizing power of PVC resin. Furthermore, for this second variant, a temperature greater than or equal to the ambient temperature and less than or equal to 150°C, preferably less than or equal to 145°C, and more preferably less than or equal to 100°C, is preferred in order to avoid any degradation of the PVC resin, for example by dechlorination reaction.

[0116] At the end of all steps a) b) and c), the AP is mainly in liquid form in an aqueous phase contained in the liquid effluent 4. Said liquid effluent 4 may contain one or more liquid phases, for example a single liquid phase (monophasic liquid) or two liquid phases (biphasic liquid), in particular depending on the nature of the extraction solvent (for example miscible or immiscible with water) and / or the operating conditions chosen.

[0117] Step d) of liquid-solid phase change of phthalic acid

[0118] The process according to the invention comprises a step d) of changing the phase of the AP from the dissolved state in the aqueous phase obtained at the end of all the steps a), b) and c) (liquid effluent 4) to a solid state allowing its recovery in a subsequent step e) of solid-liquid separation. This liquid-solid phase change can advantageously be carried out by means of one or more crystallization or precipitation operations according to techniques known to those skilled in the art, such as, but not limited to, cold-wall crystallization, the use of a precipitating agent, batch distillation, etc., said techniques being used alone or in combination, in any order.

[0119] This step d) of liquid-solid phase change therefore makes it possible to produce at least one mixed stream comprising an aqueous liquid phase depleted in phthalic acid and a second solid phase enriched in phthalic acid. This is stream 5 in Figures 1 and 4, stream 19 in Figures 2 and 5, and stream 22 in Figures 3 and 6.

[0120] In the embodiment shown in [Fig.3], which is one of the preferred embodiments according to the invention, the aqueous liquid effluent enriched in AP 21 is for example cooled to a temperature between 10°C and ambient temperature, for example a temperature of 15°C, via the implementation of a cold wall crystallization so as to cause the precipitation of the AP to obtain the mixed stream 22 comprising AP in the solid state.

[0121] Step e) of solid-liquid separation for recovery of the AP

[0122] The process according to the invention includes a solid-liquid separation step e) carried out on the mixed stream (5, 19 and 22 according to embodiments) from step d), comprising a second solid phase enriched in phthalic acid (phthalic acid in solid state), to produce at least one solid stream comprising the AP 6 in order to recover the AP and a liquid effluent (11, 14 or 20 according to embodiments) comprising residual water from the hydrolysis step b).

[0123] The residual water may still include dissolved phthalic acid in low concentration.

[0124] The AP of the solid stream 6 is in powder form.

[0125] The solid-liquid physical separation of the mixed stream from step d) can advantageously be carried out according to techniques known to the person skilled in the art such as, but not limited to, filtration, centrifugation, for example the use of hydrocyclones, electrostatic precipitation or decantation, said techniques being used alone or in combination, in any order.

[0126] In the embodiment shown in [Fig.3], which is one of the preferred embodiments according to the invention, the mixed effluent 22 is for example treated by centrifugation so as to obtain the solid stream comprising the AP 6 and an aqueous stream 14, preferably returned in whole or in part to step b) of the process according to the invention.

[0127] According to one or more embodiments (not shown in the figures), steps d) and e) are implemented within the same unit operation.

[0128] Phthalic anhydride can be produced by sending the solid stream of AP 6 to a dehydration step, the phthalic anhydride being the starting compound used to synthesize the phthalates of PVC. The dehydration of AP to form phthalic anhydride is known, and such a dehydration step can be carried out as described, for example, in US patent 3720692.

[0129] Step g) of removing the extraction solvent before step c) (optional)

[0130] According to the first embodiment of the process of the invention, the process according to the invention preferably comprises a step g) enabling the removal of at least a portion of the extraction solvent 7, and ideally all of said solvent, used in step a). This step g) is carried out downstream of the solid-liquid separation step c) and upstream of step b) of the process according to the invention, as illustrated by examples in Figures 1 to 3). The removal, at most total, of the extraction solvent makes it possible to obtain a liquid effluent 12, at least concentrated in the phthalate(s) extracted in step a), and ideally free of the extraction solvent. This liquid stream concentrated in said phthalate 12 is sent to step b).This step (g), while allowing the continued operation of a liquid effluent with rheological properties compatible with the various embodiments according to the invention, promotes the hydrolysis reaction involved in step (b) by a favorable shift in the thermodynamic equilibrium of said reaction towards the formation of the AP. Furthermore, the extraction solvent thus removed can be recovered and returned at least to step (a) of the process according to the invention.

[0131] Preferably, only part of the extraction solvent is removed at this stage.

[0132] The removal of some or all of the extraction solvent 7 is advantageously carried out by evaporation using techniques known to those skilled in the art, such as distillation, evaporation, liquid-liquid separation, etc., said techniques being used alone or in combination, in any order. Step g) may thus include a gas-liquid separation, preferably evaporation of the solvent, for example using a series of expansion balloons. When the extraction solvent comprises at least one short-chain, linear or branched aliphatic alcohol of molecular formula CnH2n+iOH with n < 4, said extraction solvent is preferably eliminated.

[0133] In the embodiment shown in [Fig. 3], which is one of the preferred embodiments according to the invention, the liquid stream 3 containing the phthalate(s) extracted in step a) and obtained from step c) is treated by evaporation during the optional step g) so as to obtain the liquid stream 12 concentrated in said phthalate(s), which is itself sent to step b). The extraction solvent is typically a solvent immiscible with water, for example toluene, and is not completely removed during step g), which allows this immiscibility to be used in the downstream steps of the process for separating the components of stream 12, and in particular phthalic acid, from the other compounds. The extraction solvent thus recovered is preferably recycled, at least in part, in the form of stream 13, in step a). Optional separation step(s) f)

[0134] Depending on the choice of extraction solvent and the various embodiments of the process according to the invention, including the optional step g) described above, a liquid effluent 4 enriched in at least the AP is obtained at the end of step b) of said process. This liquid effluent 4 comprises an aqueous phase containing the AP. The chemical nature and quantity of the other constituents of said stream vary according to the chosen embodiments and can have an impact on the nature of the medium; typically, the liquid effluent 4 can be single-phase or two-phase. The process according to the invention can thus include one or more optional liquid-liquid and / or liquid-gas separation steps located upstream and / or downstream of steps d) and e) of the process according to the invention for: - to promote the implementation of steps d) and e), and therefore the obtaining of at least one solid stream including AP 6 in order to recover the AP, and / or - recover and return to the process the residual water from the hydrolysis step b) (flow 14) and the extraction solvent (flow 15), and / or - recover and return to the process any unconverted and / or partially converted phthalate(s) resulting from hydrolysis step b), and / or - to recover alcohols, by-products of the chemical hydrolysis reaction, which can be recovered or burned to produce part of the energy required for the process according to the invention.

[0135] The optional separation step(s) f) may be carried out according to methods well known to those skilled in the art, such as, but not limited to, distillation, decantation, evaporation, liquid-liquid extraction, etc., carried out alone or in combination. The operating conditions of this step or these steps (temperature, pressure, etc.) are determined according to the separation method chosen.

[0136] In particular, one or more separation steps f) (cf. steps fl) to f4) described below) are carried out directly upstream of step d) or downstream of step e) to separate at least one aqueous liquid phase (i.e. which contains water) from other compounds in liquid or gas phase.

[0137] Some of said compounds which comprise extraction solvent, or phthalate extracted in step a) and not converted and / or partially converted in step b), or water, may advantageously be recycled respectively in step a) or in step b).

[0138] Figures 1 to 6 show different separation stages fl), f2), f3), f4) and f5), and are described in more detail below.

[0139] Steps f1) and f2) are carried out directly downstream of step e). Steps f3) and f4) are carried out directly upstream of step d). Step f5) is a separation step directly downstream of separation step f4).

[0140] According to one or more embodiments of the invention, and provided that the extraction solvent has not been totally removed from the stream 3 via step g) when it is implemented, said solvent and the operating conditions of the process of the invention are chosen so that said solvent and water 9 form a single liquid phase of the effluent 4 containing at least the AP, any other components: phthalates extracted in step a) and not converted, API, and AL. According to this or these embodiments, shown in Figures 1 and 4, the flows obtained at the end of step e) comprise the solid flow including the AP 6 and a liquid effluent 11 including residual water (from step b)), said liquid effluent 11 being in the form of a single-phase liquid phase. The choice of a water-miscible solvent, such as MEK or a MEK7 methanol mixture, can allow the obtaining of a single-phase liquid phase for effluents 4 and 11 from steps b) and e) of the process respectively. The said single-phase liquid effluent 11 comprises water (in particular residual water from step b)), extraction solvent, and possibly the phthalates extracted in step a) and not converted, the APIs and the ALs. From said single-phase liquid effluent 11, it is then possible, according to separation methods well known to those skilled in the art, for example distillation with lateral drawing-off or liquid-liquid extraction, to separate, in a step fl) preferably directly downstream of step e), not only the extraction solvent (stream 15) and residual water (effluent 14), but also the ALs (stream 17) and very advantageously the APIs with possibly the phthalates extracted in step a) and not converted (stream 16). According to the first and second variants of the process according to the invention, the flow 15 The stream containing the extraction solvent and the stream 14 containing water can then advantageously be returned to steps a) and b) of the process according to the invention, respectively. Similarly, the stream 16 containing the APIs, possibly with the phthalates extracted in step a) but not converted, is advantageously returned to step b), so as to continue the chemical reactions leading to the PA and thus improve the PA yield.

[0141] According to one variant (not shown), the extraction solvent can be completely extracted from stream 3 in step g), and step b) can be carried out by a person skilled in the art so that the effluent exiting said step b) forms a single liquid phase containing at least residual water and the AP, and optionally the phthalates extracted in step a) and not converted, the API, and the AL. The steps carried out downstream are identical to steps d), e), and fl) described above in relation to [Fig. 1], except that the extraction solvent is no longer present downstream of step g), and therefore there is no production of a stream 15 in step fl).

[0142] According to one or more embodiments of the invention, and provided that the extraction solvent has not been totally removed from the stream 3 during step g) when it is carried out, said solvent and the operating conditions of the process of the invention are chosen so that said solvent and water 9 form a first liquid phase of the effluent 4 containing at least the AP, a second liquid phase not miscible with the first also being formed and comprising at least the phthalates extracted in step a) and not converted. According to this or these embodiments, shown in Figures 2 and 5, it is possible to separate in a step f3), preferably directly upstream of step d), at least the two previous immiscible phases so as to obtain at least one stream 18 comprising the first liquid phase containing water and solvent as well as the AP, and a stream 16 comprising the second liquid phase immiscible with the first, which is an organic phase, containing at least the APIs and phthalates extracted in step a) and not converted. The choice of a water-miscible solvent, such as MEK or a MEK7 methanol mixture, is compatible with obtaining two immiscible liquid phases in the effluent 4. The stream 16 is advantageously returned to step b) of the process according to the invention, so as to continue the chemical reactions leading to the AP and thus improve the AP yield. The streams obtained at the end of step e) then comprise the solid stream including the AP 6 and a liquid effluent 20 comprising residual water (from step b)), said liquid effluent 20 being in the form of a single-phase liquid phase comprising water and extraction solvent. From said single-phase liquid effluent 20, it is then possible, according to well-defined separation methods, to known to those skilled in the art, for example distillation), to separate at a step f2), preferably directly downstream of step e), the extraction solvent (stream 15) and water (stream 14), which can advantageously be reused respectively at step a) and step b) as described above in relation to figures 1 and 4. According to this or these embodiments, and depending on their chemical nature, the ALs can indifferently be present in the stream 16 from the separation step f3) and / or the stream 20 from step e), and be eliminated accordingly in the form of a stream 17 exiting the process, before recycling the various streams 14, 15 and 16.

[0143] According to one variant (not shown), the extraction solvent can be completely extracted from stream 3 in step g), and step b) can be carried out by a person skilled in the art such that the effluent exiting said step b) comprises at least a first liquid phase containing at least the AP and a second liquid phase immiscible with the first containing the phthalates extracted in step a) and not converted, and the AL. The downstream steps carried out are identical to steps d), e), f2) and f3) described in relation to [Fig. 2], except that the extraction solvent is no longer present downstream of step g), and therefore there is no production of a stream 15 in step f2).

[0144] According to one or more embodiments of the invention, and provided that the extraction solvent has not been completely removed from stream 3 in step g) when it is implemented, said solvent and the operating conditions of the process of the invention are chosen such that said solvent and water 9 form two immiscible liquid phases of the effluent 4. The first of these liquid phases is an aqueous phase containing at least the AP; it comprises the residual water from step b) and the AP, and is immiscible with the extraction solvent. The second of these liquid phases is an organic phase comprising the extraction solvent, and containing at least the phthalates extracted in step a) and not converted, the APIs and the ALs. According to this or these embodiments, represented in figures 3 and 6, it is possible to separate at a step f4), preferably directly downstream of step d), at least the two preceding immiscible phases so as to obtain at least one stream 21 comprising the aqueous liquid phase containing the AP and at least one stream 23 comprising the organic phase containing the extraction solvent. The choice of an extraction solvent immiscible with water, such as toluene, can allow the obtaining of said first aqueous liquid phase immiscible with the organic liquid phase comprising the extraction solvent forming the effluent 4.

[0145] Implementing steps d) and e) from the stream 21 leads to obtaining at least the solid stream including the AP 6 and at least the aqueous stream 14, preferably returned in whole or in part to step b). Starting from the organic liquid flow 23, it is possible, according to methods of se Preparations well known to those skilled in the art, for example, well-known liquid-liquid or liquid-gas separation methods such as distillation, decantation, evaporation, liquid-liquid extraction, etc., carried out alone or in combination, can be used to separate, in step f5), not only the extraction solvent (stream 15), but also the ALs (stream 17) and, very advantageously, the APIs, possibly with the phthalates extracted in step a) and not converted (stream 16). Stream 16 can advantageously be returned to step b), so as to continue the chemical reactions leading to the PA and thus improve the PA yield. Similarly, stream 15 can advantageously be returned to step a). Recycling process

[0146] The present invention also relates to a method for recycling a PVC-based object containing at least one phthalate, said recycling method comprising: - the packaging of the PVC-based object including at least one grinding or shredding of the PVC-based object to form a PVC charge in the form of particles; - the recovery of the AP and a reusable target PVC plastic from said PVC feed in the form of particles according to the process according to the first aspect of the invention described above in detail. The PVC-based object conditioning step may include the various steps detailed above for the preconditioning of the PVC load before its introduction in step a).

[0147] From a circular economy perspective, it is advantageous to use the phthalic acid obtained by the described recovery process to obtain phthalates suitable for the formulation of flexible PVC plastics and / or to use the target PVC plastic produced by the recovery process according to the invention to manufacture a new flexible PVC-based object. Such an object can then be more easily manufactured to meet current phthalate standards and include only REACH-compliant phthalates, by being made from raw materials that comply with or are adapted to comply with said standards, i.e., the recovered target PVC plastic free of non-REACH-compliant phthalates, and the AP enabling the production of REACH-compliant phthalates. Manufacturing process

[0148] The present invention also relates to a method of manufacturing a flexible PVC-based object comprising recycled PVC plastic and / or a phthalate made from phthalic acid recovered by the process according to the first aspect of the invention.

[0149] Such a manufacturing process typically includes a step of recovering phthalic acid and a reusable PVC target plastic from a feedstock of PVC, as detailed above, then a step of mixing said reusable target PVC plastic with additives, then a step of shaping said mixture. Examples

[0150] This example illustrates the invention without limiting its scope, and in particular illustrates the extraction of a phthalate contained in a PVC plastic and the conversion of the phthalate into phthalic acid in the presence of a catalyst and water.

[0151] 18.2 g of a PVC plastic filler (from PVC-based articles of the "tube" type medical”), in the form of medium-sized extrudates of 2 mm, containing 4.4 g of di-decyl phthalate (DIDP), are introduced into a reactor stirred by a mechanical stirring system, of the paddle type. 53.19 g of water and 35.11 g of acetophenone (organic extraction solvent) are then added, with an acetophenone / water mass ratio of 0.66, an acetophenone / DIDP molar ratio of 29.7, and a water / DIDP molar ratio of 300. 0.13 g of a catalyst, which is p-toluenesulfonic acid (APTS), are then added to the previous mixture so that the APTS / DIDP mass ratio is 3%.

[0152] The reactor is hermetically sealed, purged with nitrogen and then heated to 100°C with an autogenous pressure of the order of 1.2 MPa and maintained in these conditions for 4 h under agitation of 1000 rpm.

[0153] After 4 hours, a solid and a liquid are obtained and separated under heat at 65°C, yielding a PVC solid with a very low phthalate content on the one hand and a liquid on the other. This liquid is then cooled to 10°C, leading to the precipitation of a second solid consisting mainly of phthalic acid. The resulting suspension is filtered. The remaining liquid (filtrate) is then allowed to react three times under the same conditions as previously described. After each reaction step, a precipitation step, identical to that specified above, extracts a solid phase consisting mainly of phthalic acid, increasing the final phthalic acid yield. Following this protocol, the secondary solid fractions are combined and analyzed.

[0154] Gas chromatography with flame ionization detection (GC-FID) analysis of the secondary solid phase shows that it contains 1.47 g of phthalic acid resulting from the conversion of DIDP and 0.30 g of monomethyl phthalate (2-(isodecoxycarbonyl)benzoic acid) resulting from the partial hydrolysis of DIDP. The liquid contains 2.96 g of isodecanol (ClO2H22O) resulting from the hydrolysis reaction of DIDP. Identification was made possible by comparing the retention times of pure analytical standards, and quantification was performed by determining the response coefficients obtained from the analysis of these same standards.

[0155] The resulting solid was pre-fractionated by SEC size exclusion chromatography The preparative analysis was performed using a dual optical (UV / Visible) and refractometry (RI) detection system. The collected fractions were analyzed by high-performance liquid chromatography (HPLC) with quantitative UV-Visible optical detection. The results indicate the presence of DIDP in the target PVC plastic at a concentration below 1000 ppm, which complies with current European regulations.

[0156] These results show that a phthalate-free PVC is obtained in accordance with the invention, and that the DIDP has been converted to 99.9%. In this example, the extraction of the DIDP and its conversion are carried out in the same step.

Claims

Demands

1. A process for recovering phthalic acid and a reusable target PVC plastic from a PVC feed containing at least one phthalate, comprising the following steps: a) a solid-liquid extraction of said PVC feed in the form of particles (1) by contacting said particles of the PVC feed with at least one organic extraction solvent (7) of said phthalate, to produce a liquid phase enriched in said phthalate and a first solid phase comprising PVC plastic depleted in said phthalate; b) a chemical transformation of said phthalate extracted in step a) into phthalic acid of formula C6H4(COOH)2 by hydrolysis with water in the presence of an acid hydrolysis catalyst to produce an aqueous phase comprising said phthalic acid;(c) a solid-liquid separation between said first solid phase and said liquid phase enriched in said phthalate or said aqueous phase comprising said phthalic acid to produce at least one solid stream comprising the PVC plastic depleted in said phthalate (8) in order to recover said target PVC plastic; (d) a phase change of phthalic acid from the dissolved state in said aqueous phase to a solid state to produce a mixed stream comprising an aqueous liquid phase depleted in phthalic acid and a second solid phase enriched in phthalic acid (5, 19, 22); (e) a solid-liquid separation between the phthalic acid in the solid state from step (d) and the aqueous liquid phase of said mixed stream to produce a solid stream of phthalic acid (6) and a liquid effluent (11, 14, 20) comprising residual water from step (b).

2. A process according to claim 1, wherein steps a) and b) are carried out within the same unit operation producing a stream (24) comprising at least said aqueous phase comprising said phthalic acid and said first solid phase.

3. A method according to claim 1, wherein steps a) and b) are carried out as two separate unit operations, step a) producing a stream (2) comprising said liquid phase enriched in said phthalate and said first solid phase sent to step c) carried out between steps a) and b), step c) producing said stream comprising the PVC plastic depleted in said phthalate (8) and a first liquid stream (3) comprising said liquid phase enriched in said phthalate.

4. A process according to claim 3, comprising a step g) of removing at least a portion of the organic extraction solvent from said first liquid stream (3) prior to step b), to produce a first concentrated liquid stream comprising said phthalate sent to step b).

5. A process according to claim 4, wherein the organic extraction solvent recovered in step g) is recycled at least in part in step

6. dj. A process according to any one of the preceding claims, wherein said solid stream comprising the phthalate-depleted PVC plastic (8) separated in step c) is recycled at least in part in step

7. dj. A process according to any one of the preceding claims, wherein said organic extraction solvent (7) is selected from the list consisting of ketones, ethers, glycol ethers, cyclic and aromatic hydrocarbons, short-chain aliphatic alcohols, linear or branched, of molecular formula CnH2n+iOH with n < 4, n being a non-zero natural number, and mixtures thereof.

8. A process according to claim 7, wherein said organic extraction solvent (7) is selected from the list consisting of methyl ethyl ketone, diethyl ketone, 4-heptanone, 2,4-dimethyl-3-pentanone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, acetophenone, tetrahydrofuran, cyclohexane, xylenes, toluene, methanol, ethanol, n-propanol, z-propanol, and mixtures thereof, and preferably is selected from said alcohols, ketone / alcohol mixtures, hydrocarbon / alcohol mixtures, cyclohexane, toluene, xylenes, methoxycyclopentane, methyl isobutyl ketone, cyclopentanone, acetophenone, and preferably said organic extraction solvent (7) is toluene, methyl ethyl ketone, acetophenone or a methyl ethyl ketone / methanol mixture.

9. A process according to any one of the preceding claims, wherein the hydrolysis in step b) is carried out in the presence of a homogeneous acid hydrolysis catalyst selected from the list of mineral Brønsted acid catalysts, preferably hydrochloric acid, sulfuric acid, phosphoric acid, organic Brønsted acid catalysts, preferably p-toluenesulfonic acid, and Lewis acid catalysts, preferably AlF3, or a he- acidic terogen selected from the list consisting of aluminas, chlorinated aluminas, fluorinated aluminas, mesoporous aluminosilicates, zeolites and their mixtures with other oxides, ion exchange resins (H+), preferably sulfonic resins.

10. A process according to any one of the preceding claims, wherein the hydrolysis in step b) is carried out at a temperature between ambient temperature and 150°C, preferably between 40°C and 130°C, at a pressure between atmospheric pressure and 5.0 MPa, preferably between atmospheric pressure and 2.0 MPa, and for a duration between 1 minute and 10 hours, preferably between 10 minutes and 4 hours.

11. A process according to any one of the preceding claims, wherein the hydrolysis in step b) is carried out such that the molar ratio between the amount of water and the amount of said phthalate extracted in step a) is between 100 and 9000.

12. A process according to any one of the preceding claims, wherein step d) comprises at least one phthalic acid precipitation step, preferably comprising cooling to a temperature between 10°C and ambient temperature.

13. A method according to any one of the preceding claims, wherein said at least one phthalate of said PVC filler is a phthalate of molecular formula C6H4(COORi)(COOR2) having ester groups in the ortho position of the benzene ring, Ri or R2 being independently selected from one of the elements of the group consisting of an alkyl chain, linear or branched or cyclic, an alkoxyalkyl chain, linear or branched, or an aryl or alkylaryl chain, Ri and / or R2 preferably comprising between 1 and 20 carbon atoms, or even between 1 and 15 carbon atoms.

14. A process according to any one of the preceding claims, wherein said target PVC plastic is free of said phthalate, and preferably comprises less than 0.1% by mass in total of phthalates selected from the list consisting of dibutyl phthalate, dioctyl or diethylhexyl phthalate, benzyl butyl phthalate, dibutyl phthalate, diisobutyl phthalate, dipentyl phthalate, dii-sopentyl phthalate, n-pentyl isopentyl phthalate, dihexyl phthalate, bis(2-methoxyethyl) phthalate, and mixtures thereof.

15. A process for recycling a PVC-based article containing at least one phthalate comprising: - the packaging of said PVC-based object comprising at least one grinding or shredding of said PVC-based object to form a charge of PVC in the form of particles; - the recovery of phthalic acid and a reusable target PVC plastic from said PVC feed in particle form according to any one of claims 1 to 14.

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