Selective extraction process for polyethylene terephthalate (PET) from a complex mixture of thermoplastics and thermosets

Abstract

Method for the selective extraction of polyethylene terephthalate (PET) from a complex mixture of thermoplastics and thermosets. The present invention relates to a method for extracting polyethylene terephthalate (PET) from a solid material containing it in a mixture with one or more auxiliary thermoplastic materials and / or one or more thermoset materials, optionally at least one metal. The method comprises at least the steps of: - Contacting said solid material with a solvent selected from dimethyl isosorbide, benzyl acetate, and mixtures thereof in a reactor; - Selectively solubilizing said polyethylene terephthalate by heating the mixture formed from said material and said solvent, under stirring, at a temperature ranging from 185°C to 220°C; - Isolating said solvent containing the solubilized polyethylene terephthalate (PET) from said mixture; - Precipitating said polyethylene terephthalate in said isolated solvent.and- Recover the polyethylene terephthalate precipitate. Figure for the summary: None,

Description

Title of the invention: Process for the selective extraction of polyethylene terephthalate (PET) from a complex mixture of thermoplastics and thermosets. Technical field

[0001] The present invention relates to the treatment of plastic waste and more specifically aims to propose a method for isolating polyethylene terephthalate, PET, contained in a complex mixture of different materials (thermoplastics, thermosets, metals, plant fibers, inorganic materials), such as the mixtures constituting a seat cover or vehicle seat cover. Previous technique

[0002] Since the first third of the 20th century, so-called "plastic" materials (polymer materials) have experienced incredible growth due to the properties associated with them, such as their lightness, flexibility, durability, ease of preparation and shaping, their barrier properties to gas or moisture, and finally their great diversity and versatility.

[0003] Moreover, they have been and are very easily produced on a large scale while remaining inexpensive because they are mainly produced from petroleum-based resources.

[0004] The evolution of global plastic production bears witness to this; it has increased twentyfold since the 1960s. In 2021, it amounted to 390.7 million tonnes. The main sectors using plastics are, in order of importance: packaging (44%), construction and building (18%), automotive (8%), the electrical and electronic equipment industry (7%), household appliances and the sports and leisure industry (7%), and agriculture (7%). The main types of polymers produced are, in order of importance: polyolefins (PP, LDPE, MDPE, HDPE, 46%), PVC (13%), PET (6%), polyurethanes (5.5%), thermosetting resins excluding polyurethanes (epoxy and others, 7.1%), and polystyrene (5.3%).

[0005] Given their widespread use, there has been a correspondingly sharp increase in their disposal. The proportion (% by mass) of plastic contained in collected municipal waste increased from less than 1% in 1960 to more than 10% in developed and developing countries in 2005. The world now faces a growing problem of biosphere pollution from plastics and their derivatives linked to their uncontrolled dispersal / degradation in the environment.

[0006] Today, industrialists and researchers are mobilizing to rethink the manufacture, use, reuse and / or recycling of plastic waste in order to move towards a circular economy model.

[0007] The present invention falls within this approach by focusing particularly on the widely used polymer polyethylene terephthalate (PET). Polyethylene terephthalate is a polyester-type thermoplastic obtained by condensation from a series of terephthalic acid and ethylene glycol units. Among the properties of PET, the following distinctive characteristics can be listed: transparency, barrier properties, high glass transition temperature (greater than 70°C), good mechanical properties, semi-crystalline structure, and high melting point (> 250°C). As post-consumer waste, PET is most often recycled very little.

[0008] Among the various polymer recycling techniques, the most widely used for many thermoplastics such as PET is mechanical recycling. Current mechanical recycling processes, such as those illustrated in CN 107 175 783 and JP 2011 006521, include a series of steps: collection, sorting, grinding, washing, a possible second sorting, and finally extrusion. These steps allow the conversion of mixed post-consumer waste into recycled PET. For mechanical recycling, it is important to separate the different plastics before the extrusion step. The critical step is therefore the sorting stage. However, when the solid to be processed is a mixture of very finely ground polymers, it is not possible to separate the different polymers it contains using one of the sorting techniques (manual, optical, density, flotation, electrostatic) currently employed before the recycling stage (mechanical or chemical).Finally, a disadvantage of mechanical PET recycling is that the recovered polymer has degraded mechanical and rheological properties due to random splitting caused by the thermomechanical treatment undergone by the macromolecular chains during extrusion. Thus, the chains can lose approximately 26% of their molar mass during a mechanical recycling process.

[0009] The other major family of processes developed for recycling PET (and particularly polymers obtained by polycondensation) is chemical recycling by depolymerization / chemical degradation of macromolecular chains to form monomers or their derivatives, which can be used as building blocks to resynthesize virgin PET with the same properties as the initial virgin material. This chemical recycling method is most often based on a solvolysis technique; the most studied are: hydrolysis (EP 3 320 033), methanolysis (EP 4 136 159), alcohololysis, taminolysis, glycolysis (EP4 087 895 and WO 2016 / 096768), and ammonolysis.

[0010] In these processes, the solvent is also a reagent and reacts with the ester groups in the case of PET to reform either the initial monomers or derived molecules. The limitation of this technique is that it can be sensitive to impurities / additives and is not suitable for complex polymer blends, specifically streams containing mixtures of polycondensates (polyurethanes, polyamides, epoxies, PET). Furthermore, it is a longer recycling method than mechanical recycling processes: to return to the monomer, it is necessary to resynthesize the polymer, whereas with the other two techniques, a polymer is recovered that simply needs to be reformulated and reshaped. Description of the invention

[0011] Within the scope of the present invention, the aim was therefore to develop a method distinct from previous techniques and capable of enabling the selective extraction of PET from complex mixtures containing it, while avoiding both the sorting operations required in mechanical recycling and significant deterioration of the chemical structure of the PET polymer chains. Summary of the invention

[0012] Thus, a first aspect of the present invention aims to protect a process for the selective extraction of polyethylene terephthalate, PET, from a solid material containing it in a mixture with: - one or more additional thermoplastic materials selected from polyolefins, in particular polyethylenes (PE), polypropylenes (PP), polyvinyl chlorides (PVC), ethylene vinyl alcohols (EVOH), ethylene vinyl acetate (EVA), elastanes, polyamides, in particular nylons 6 and 6 / 6, elastomers, polyacetals, in particular polyoxymethylene, and mixtures thereof, and / or - one or more thermosetting materials selected from polyurethanes, in particular polyurethane foam, epoxy resins and their mixtures, - and where applicable at least one metal, said process comprising at least the steps of: - In a reactor, bring said solid material into contact with a solvent chosen from dimethyl isosorbide, benzyl acetate, and mixtures thereof. - To selectively solubilize said polyethylene terephthalate by heating the mixture formed from said material and said solvent, under agitation and at a temperature ranging from 185 °C to 220 °C, - Isolate said mixture, in particular by filtration, said solvent containing the solubilized polyethylene terephthalate, PET, - Precipitate said polyethylene terephthalate in said isolated solvent, in particular by cooling said isolated solvent to a temperature below 185 °C, and - Recover the polyethylene terephthalate precipitate.

[0013] For the purposes of the invention, the term "selective" means that the PET is isolated from the solid material in a purified form free from any other thermoplastic and / or thermosetting material, this purified form may nevertheless include a coloring pigment.

[0014] Admittedly, the technique for dissolving thermoplastics, and in particular PET, is already known and used for recycling them (WO 2022 / 221832; WO 2022 / 229129; CN 11 610 2782). However, to the inventors' knowledge, this technique has never been used to selectively extract PET from a waste stream containing a variety of materials such as thermoplastics, thermosets, metals, and cellulosic fibers, like, for example, shredded automotive seat covers. Thus, in document WO 2022 / 221832, this technique is applied only to plastic waste consisting of food containers, such as water bottles, which combine only PET and coloring additives. It is used to separate this PET from the associated coloring additives and make it possible to recycle it in a transparent form.In document CN 11 610 2782, this technique is also used to recycle PET by dissolution from a waste stream composed solely of PET, i.e., in the absence of any additional thermoplastic and / or thermosetting material. As for document WO 2022 / 229129, it describes a recycling process for polyesters, and in particular for PET constituting mixed textile products containing PET and cellulosic fibers (cotton, linen, etc.), and therefore in the absence of any additional thermoplastic and / or thermosetting material.

[0015] Against all expectations, the inventors have found that it is now possible to extract PET selectively and without significant degradation from a material containing it mixed with a plurality of ancillary compounds such as thermoplastics, thermosets, metals and cellulosic fibers, provided that a very specific operating protocol and PET solvent are used.

[0016] Thus, the process of the present invention can be applied to the extraction of PET contained in a used vehicle seat or seat cover and / or in production waste from such seats or covers, generally intended for incineration and / or landfill. By enabling the selective extraction of PET from such a solid material, the process of the present invention allows its reuse as recycled PET, for example, in an extrusion process, or its recovery as a raw material in a chemical recycling process.

[0017] Finally, the process of the present invention has the significant advantage of being environmentally friendly. Indeed, the solvents used in the contacting step are "green" and non-hazardous solvents, that is to say They are non-toxic, non-CMR, and some are even bio-based. They are chemically stable and easily recyclable by distillation.

[0018] According to another aspect of it, the present invention therefore aims at the use of a process according to the invention for the selective extraction of PET contained in plastic waste such as, for example, a vehicle seat, a vehicle seat cover, a used vehicle seat cover and / or a production waste thereof.

[0019] It also aims to protect recycled PET, in particular coloured PET, obtained by a process of the invention.

[0020] Other features, variations and advantages of the process according to the invention will become clearer from the description, examples and figures that follow.

[0021] In the following text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are meant to mean that the limits are included, unless otherwise stated. Brief description of the drawings

[0022] [Fig. la] and [Fig.lb] present the IR spectra of the reference PET and of the PET extracted in example 1 according to a process of the invention.

[0023] [Fig.2] presents the ATG curve of the reference PET.

[0024] [Fig.3] shows the TGA curve of PET extracted in example 1 according to a process of the invention.

[0025] [Fig.4a] presents the normalized GPC-SECs chromatograms of the reference PET and PET extracted in example 1 according to a process of the invention.

[0026] [Fig.4b] shows the GPC-SEC normalized molar mass distributions of PET of reference and PET extracted in example 1 according to a process of the invention.

[0027] [Fig.5a] and [Fig.5b] present the IR spectra of the reference PET and of the PET extracted in example 2 according to a process of the invention.

[0028] [Fig.6] presents the ATG curve of PET extracted in example 2 according to a process of the invention.

[0029] [Fig.7a] presents the normalized GPC-SECs chromatograms of the reference PET and PET extracted in example 2 according to a process of the invention.

[0030] [Fig.7b] shows the GPC-SEC normalized molar mass distributions of PET of reference and PET extracted in example 2 according to a process of the invention.

[0031] [Fig.8a] and [Fig.8b] present the IR spectra of the reference PET and of the PET extracted in example 3 according to a process of the invention.

[0032] [Fig.9] presents the TGA curve of PET extracted in example 3 according to a process of the invention.

[0033] [Fig. 10a] presents the standardized GPC-SECs chromatograms of the reference PET and of the PET extracted in example 3 according to a process of the invention.

[0034] [Fig. 10b] presents the normalized GPC-SEC molar mass distributions of the reference PET and the PET extracted in example 3 according to a process of the invention.

[0035] [Fig. 11] presents a GC chromatogram obtained for DMI and solvents brought into contact with PET samples 1 and 2, showing the presence of trace amounts of solvent (dimethyl isosorbide) in recycled PET. Detailed description Solid material that can be processed according to the invention

[0036] As can be seen from the foregoing, the process according to the invention is particularly effective for isolating the PET component from a complex mixture of thermoplastic materials and / or thermosetting materials, such as, in particular, plastic waste combining PET: - one or more additional thermoplastic materials selected from polyolefins, for example polyethylenes PE, polypropylenes PP, polyvinyl chlorides PVC, ethylene vinyl alcohols EVOH, ethylene vinyl acetates EVA, elastanes, polyamides, such as nylons 6 and 6 / 6, elastomers, polyacetals, such as polyoxymethylene, and mixtures thereof, and / or - one or more additional thermosetting materials selected from polyurethanes, in particular polyurethane foam, epoxy resins, and mixtures thereof.

[0037] According to a particular embodiment, this solid material is a mixture containing PET and at least one or more additional thermoplastics in particular one or more polyethylenes, polypropylenes, polyvinyl chlorides, and polyamides, and one or more thermosets in particular one or more polyurethanes, and cellulosic fibers (cotton, linen, hemp, silk).

[0038] This type of mixture is particularly representative of the solid materials found in seat covers, especially in vehicle seat covers. Indeed, these objects generally contain PET in addition to several other thermoplastic materials, thermosetting materials such as polyurethane foam, cellulosic fibers (vegetable and / or synthetic) and metallic materials.

[0039] Thus, vehicle seat covers and seat covers can be treated according to the process of the present invention.

[0040] These vehicle seat covers and seat covers may be production waste, and / or originate from an End-of-Life Vehicle as defined in European Directive 2000 / 53 / EC of 18 September 2000. For example, production waste may be cutting waste produced when cutting parts forming a seat cover and / or a vehicle seat cover, a material intended for use in a seat cover and / or a vehicle seat cover but whose properties do not conform to a technical file.

[0041] More specifically, a seat cover, in particular a vehicle seat cover, typically comprises rigid elements and flexible elements.

[0042] The rigid elements are generally metallic rigid elements such as metal rods, non-metallic rigid elements such as plastic profiles or both.

[0043] The flexible elements are PET elements mixed with one or more components selected from: - Additional thermoplastic materials such as polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polyamides, such as nylon 6, nylon 6 / 6 or their blends, elastomers or their blends, - thermosetting materials, such as polyurethane foam or resin, and, - cellulosic fibers, such as cotton fibers, flax fibers, hemp fibers, silk fibers or their mixtures.

[0044] For obvious reasons, seat covers, in particular vehicle seat covers, are, in view of their large size, solid materials whose PET solubilization kinetics may be slower if their size is not reduced. Crushing and sorting stages

[0045] Thus, according to one embodiment, the solid material, brought into contact with the solvent according to the invention, is in the form of a grind.

[0046] In such an embodiment, the process of the invention may include, prior to the step of bringing the solid material into contact with the solvent according to the invention, at least one grinding step, in particular mechanical grinding, of the solid material to be treated.

[0047] The resulting ground material may have a particle size ranging from 1 to 100 mm, and in particular from 1 to 10 mm, with, where applicable, some traces of ground material pieces ranging in size from 10 to 50 mm.

[0048] According to a particular embodiment, the process of the invention may include bringing the solid material into contact with the solvent to form a grind having in particular a particle size varying from 1 to 100 mm and in particular from 1 to 10 mm.

[0049] The particle size of the ground material is not a determining factor in the efficiency of the process. However, it has been observed that the use of ground material advantageously accelerates the solubilization kinetics of PET.

[0050] In another embodiment, the process of the present invention may also include, between the grinding step and the contacting step, a sorting step dedicated to isolating said ground material, its thermoplastic and / or thermosetting component, for its subsequent contacting with the solvent according to the invention.

[0051] In a particular embodiment, the process may include, between said grinding step and said contacting step, a sorting step dedicated to isolating one or more thermoplastic and / or thermosetting components of said ground material for its subsequent contact with said solvent.

[0052] This sorting step also maximizes the amount of PET-containing material and thus optimizes the process yield. This step also prevents the introduction of metallic materials known to damage the reactor in which the PET solubilization reaction takes place.

[0053] In one embodiment, particularly when the solid material to be treated is derived from a source material, especially a large one, and in particular from a seat cover or a vehicle seat cover, the grinding step of the process according to the invention may include: - a shredding / crushing step of said source material to fragment it into a particle size varying from 30 mm to 120 mm, and possibly, - a subsequent granulation step of said fragments obtained.

[0054] The source material in solid material can thus be a plastic waste containing PET, in particular a vehicle seat cover, a used vehicle seat cover and / or a production waste thereof.

[0055] The implementation of the shredding / crushing step is within the knowledge of a person skilled in the art.

[0056] The granulation step can be implemented by any granulation unit known to a person skilled in the art.

[0057] As specified above, the shredded material obtained from a solid part, such as a seat cover and / or a vehicle seat cover, generally comprises both the rigid and flexible elements of that part. It is therefore advantageous for such shredded material to undergo a sorting step. According to a particular embodiment, this sorting step may include at least: - electromagnetic sorting to separate and recover: on the one hand, the rigid metallic elements, and on the other hand, the rigid non-metallic elements and the flexible elements; - density sorting of the rigid non-metallic elements and the flexible elements to separate and recover, on the one hand, the flexible elements whose density is less than or equal to the density of the flexible PET elements, and on the other hand, the rigid elements. non-metallic and flexible elements whose density is greater than the density of flexible PET elements.

[0058] The flexible elements whose density is less than or equal to the density of the flexible PET elements are then brought into contact with the solvent considered in the process of the invention.

[0059] For example, flexible elements whose density is less than or equal to the density of PET flexible elements are PET flexible elements and at least one element selected from polypropylene flexible elements, PP, polyethylene flexible elements, PE, elastomer flexible elements, flexible elements made of one or more additional thermosetting materials, cellulosic fibers, polyamides, polyvinyl chloride flexible elements, PVC and their mixtures.

[0060] The sub-steps of sorting by electromagnetism and by density are classic steps known to those skilled in the art. They know how to adapt them to the ground material obtained from the seat upholstery, in particular from the vehicle seat cover.

[0061] Advantageously, the ground material from these two sorting sub-steps can comprise at least 60% and at most 99% by weight of polyesters, mainly PET, at most 30% by weight of PU, at most 10% by weight of PE and PP, at most 10% by weight of PA, at most 5% of PVC and at most 5% of elastomer. Selective solubilization step of PET

[0062] Generally speaking, the quantity of solvent is adjusted with regard to the expected quantity of PET in the solid material to be treated.

[0063] In particular, the weight ratio between said PET and said solvent, PET / solvent, varies from 1:50 to 1:1 and in particular from 1:20 to 1:5.

[0064] As can be seen from the above, the solubilization of PET in the solvent considered according to the invention is carried out at a temperature ranging from 185 °C to 220 °C. This is a selective solubilization.

[0065] For the purposes of the invention, the expression "selective solubilization" of PET means that the PET is the compound of the thermoplastic and / or thermosetting components of the solid material being treated, predominantly solubilized in the solvent and within the temperature range required according to the invention.

[0066] In particular, the selectivity of the PET solubilization reaction is greater than 50%, in particular greater than 90%, more particularly greater than 99%.

[0067] According to one embodiment, the solvent and the material are introduced into the reactor at the same temperature, in particular ambient temperature 22 °C + / - 5 °C, and their mixture is heated there to a temperature ranging from 185 °C to 220 °C for the time necessary to solubilize the PET. This heating time can vary from 15 minutes to 3 hours.

[0068] According to a preferred embodiment, the selective solubilization reaction is carried out under an inert atmosphere, for example under nitrogen or argon, and under mechanical stirring. Isolation step of said mixture

[0069] According to a preferred embodiment, with regard to the reactor, it is equipped with a filtration system or a section dedicated to filtration in which the solid material to be treated is placed and which allows the recovery of the solvent containing the PET solute separated from any solid or insoluble fraction.

[0070] This configuration mode is also suitable for carrying out preliminary step(s) of purification of this ground material.

[0071] According to one embodiment, the reaction can be carried out within a microwave “reactor”, in which case the heating is carried out by microwaves.

[0072] The solvent containing the solubilized PET is isolated. This separation can be carried out using various common techniques, but filtration is generally preferred. Precipitation step of said PET

[0073] The PET present in solute form in the solvent thus isolated is recovered by precipitation.

[0074] This precipitation can be achieved by different methods.

[0075] It is known, in particular, that the introduction of a PET anti-solvent into the solvent containing the PET can be an effective method. However, this precipitation method is not used in the context of the present invention since it requires the use of an additional solvent.

[0076] Thus, the process according to the invention is devoid of the implementation of a PET anti-solvent.

[0077] For the purposes of the invention, a PET anti-solvent is a solvent that does not allow PET to be solubilized even at high temperatures.

[0078] In the context of the present invention, PET is precipitated by cooling the solvent containing it below the solubilization temperature of PET.

[0079] According to a particular variant, this cooling is achieved by adding the same solvent as that which is in contact with the solid material to be treated, i.e. a solvent chosen from dimethyl-isosorbide, benzyl acetate and mixtures thereof, brought to a temperature such that the temperature of its mixture with the solvent containing the solubilized PET is less than 185 °C.

[0080] In particular, the added solvent may be at a temperature below 170 °C. Precipitated PET recovery step

[0081] The PET thus precipitated is recovered, generally by filtration, where appropriate washed with dimethyl isosorbide, then dried, in particular under vacuum, especially at 120

[0082] As can be seen from the examples below, the PET extracted according to the invention is relatively pure because it is in a purified form free of any additional thermoplastic and / or thermosetting components. Furthermore, infrared and size-exclusion chromatography analyses also demonstrate this. This confirms that it does not contain any other polymers whose profiles could potentially affect its own.

[0083] It is also noted that PET is not modified in its thermal and mechanical behavior following its extraction according to the process of the invention.

[0084] In the embodiment where the process is carried out on a solid material containing PET mixed with one or more color pigments, such as, for example, the materials used to make upholstery in vehicle seats, the recovered PET is generally obtained mixed with at least one of these color pigments. Indeed, during selective solubilization, the PET dye remains in strong interaction with the polymer, and colored PET is recovered. Advantageously, reusing this colored PET to manufacture a coating of a similar color can reduce the quantity or even eliminate the need for coloring additives.

[0085] Other characteristics, variants and advantages of the composite materials according to the invention, their preparation and implementation, will become clearer from reading the examples and figures that follow, given by way of illustration and not limitation of the invention.

[0086] Although the PET extracted according to the invention is relatively pure because it is in a purified form of any additional thermoplastic and / or thermosetting component, it includes traces of solvent used in the process of the present invention.

[0087] Thus, the present invention also relates to a composition comprising recycled PET and a solvent selected from dimethyl isosorbide, benzyl acetate and mixtures thereof, in particular dimethyl isosorbide.

[0088] Advantageously, the detection of the solvent in recycled PET makes it possible to trace the PET produced by the process of the present invention.

[0089] Since the solvent is present in trace amounts in the composition comprising recycled PET, said composition may comprise less than 2% by mass of solvent relative to the total mass of said composition, in particular less than 0.5%, more particularly less than 0.1%.

[0090] The composition may consist of recycled PET and a solvent selected from dimethyl isosorbide, benzyl acetate and mixtures thereof, in particular dimethyl isosorbide.

[0091] The recycled PET in this composition can be coloured. Examples

[0092] Example 1 j. _ Recovery of recyclable PET contained in a synthetic blend of commercially available thermoplastics and thermosets

[0093] In a glass reactor, the following are placed: - 1 g of polyethylene terephthalate (CAS: 25038-59-9, supplier Goodfellow), - 0.5 g of polyamide 6 (nylon 6 or PA6, CAS: 25038-54-4, supplier Sigma Aldrich), - 0.5 g of polyamide 66 (nylon 6 / 6 or PA 6 / 6, CAS: 31131-17-2, supplier Sigma Aldrich), - 0.5 g of polypropylene (PP, CAS: 9003-07-0, Mn 97000 g.mol1 and Mw 340 000 g.mol1, supplier Sigma Aldrich), - 0.5 g of polyurethane (MDI [4,4'-diphenylmethylene diisocyanate] polyester / polyether polyurethane, CAS: 68084-39-9), and - 20 mL of dimethyl-isosorbide (Biorenewable Reagent plus grade > 99%, CAS: 5306-25-4, supplier Sigma Aldrich).

[0094] After adding a magnetic stir bar, the reactor containing the mixture is heated in a preheated silicone oil bath at 170 °C and stirred using a hot plate equipped with a magnetic stirring system. After 3 hours, the solution is allowed to return to room temperature, all the supernatant solid phase is removed, and the solvent is drained. 20 mL of clean solvent is added, and the mixture is heated with stirring for 30 minutes at 170 °C to wash off the solid. After cooling, the washing solvent is drained, and another 20 mL of dimethyl isosorbide is added. The mixture is stirred and heated, this time, at 190 °C for 30 minutes to allow the selective solubilization of the PET contained in the mixture. The mixture is then filtered (60 µm cut-off stainless steel filter heated to 200 °C) while hot and the hot filtrate is added to a beaker equipped with a magnetic stirrer, along with 80 mL of dimethyl-isosorbide preheated to 120 °C.Mixing the two solutions causes the PET to precipitate. The solution is stirred until the mixture temperature drops to 50 °C. The solution is then vacuum-filtered to separate the precipitated PET from the solvent. The recovered cake is washed with dimethyl isosorbide, followed by ethyl acetate. The solid is finally dried under vacuum at 120 °C for 24 hours and then characterized by TGA, IR, and GPC. 0.909 g of PET were recovered at the end of the selective solubilization process, representing a recovery yield of 90.9% of the initial PET.

[0095] The PET thus isolated is characterized by infrared (IR) analysis (ATR-FTIR, using a SHIMADZU IRTracer-100), mass analysis, and GPC (Gel permeation chromatography: Waters 2695 system, hexafluoroisopropanol solvent). Analysis temperature of 40 °C, a Waters 2414 refractive index detection module, calibration was carried out with narrow polymethyl methacrylate (PMMA) calibrators and TGA analyses (NETZSCH STA 409 PC system).

[0096] The IR analyses performed and shown in Figures 1a and 1b confirm qualitatively and semi-quantitatively the obtaining of a colored form of PET purified of all other thermoplastic and / or thermosetting material and recyclable as PET material. A perfect overlap of the spectra of the recycled polymer and the reference PET is observed. No additional bands are observed on the spectra, confirming the effectiveness of the process used for the separation and recycling of PET contained in mixed plastic waste.

[0097] The TGA curve profiles shown in Figures 2 and 3 are perfectly similar. Therefore, PET does not appear to be (qualitatively) altered in its thermal behavior after the extraction process. Furthermore, this is also a good indication that the recovered polymer does not contain other polymers whose thermal profiles would vary.

[0098] Gel permeation chromatography (GC) analyses, shown in Figures 4a and 4b, demonstrate that the recovered PET has an elution profile and molar mass distribution almost identical to that of the reference polymer. No additional peaks are identified, confirming the purity of the sample obtained.

[0099] Molar mass analyses (Table 1) reveal a slight degradation of the polymer chains, which lose between 9 and 13% of their molar mass depending on the molar mass indicator used (Mn, Mw, Mp, Mz). This value is more than twice as low as that observed in the case of PET degradation by mechanical recycling (26.4% loss for Mw).

[0100] [Tables] Sample Mn (g / mol) Mw (g / mol) Mz (g / mol) IP Mp (g / mol) Area (mg / ml) Notes Reference PET 29217 69240 118849 2.4 48803 0.264 1.9602 N / A PET extracted in example 1 according to a process of invention T 26656 60360 103320 7.3 44433 0.274 2.0064 N / A

[0101] Example 2 j. Recovery of a recyclable PET contained in a material obtained from the grinding of automotive seat covers

[0102] In a 1.5 L double-jacketed glass reactor equipped with a drain / sip valve, a stainless steel filter basket (cut-off 250 µm), and a condenser, 50 g of ground automotive seat cover material (containing, in particular, approximately 70% by mass of PET, 20% polyurethane foams, less than 10% polypropylene (PP), and less than 10% nylon 6 or nylon 66) is placed inside. From the basket, 1-1.2 L of dimethyl isosorbide preheated to 160 °C is added. The double jacket has been preheated to 170 °C. The mixture is heated and stirred (mechanical stirring) at 170 °C under an inert atmosphere (N2 flow) for 3 hours. The solvent from this first step is recovered by withdrawal. 1 L of "fresh" dimethyl isosorbide preheated to 160 °C is introduced into the reactor. The mixture is stirred under an inert atmosphere for 30 minutes while maintaining the temperature of the double jacket at 170 °C. The washing solvent is withdrawn while the solid in the reactor is retained by the filter basket. 1 L of "fresh" dimethyl isosorbide preheated to 190 °C is again introduced into the reactor. This time the mixture is stirred and heated to 190 °C under an inert atmosphere for 45 minutes to allow the selective solubilization of the PET contained in the mixture.The solvent filtered through the basket and containing the dissolved PET is withdrawn and immediately added slowly to a second 2 L reactor containing 750 mL of dimethyl isosorbide preheated to 120 °C and equipped with a stirring system. Mixing the two solutions results in the controlled precipitation of the PET. The solution is stirred until the mixture temperature drops to 50 °C. The solution is centrifuged to separate the precipitated PET from the solvent. The solid is then washed with dimethyl isosorbide, followed by ethyl acetate. Finally, the solid is dried under vacuum at 120 °C for 24 hours and then characterized by TGA, IR, and GPC. Its crystallinity is determined by densimetry using a helium pycnometer. 29.5 g of PET were recovered at the end of the selective solubilization process of the supplied industrial waste.

[0103] The isolated PET is characterized by IR infrared analysis (ATR-FTIR, using a SHIMADZU IRTracer-100), mass analysis, GPC (Gel permeation chromatography: Waters 2695 system, hexafluoroisopropanol solvent, analysis temperature of 40 °C, Waters 2414 refractive index detection module, calibration was carried out with narrow polymethyl methacrylate (PMMA) calibrators and TGA analysis (NETZSCH STA 409 PC system).

[0104] The analyses presented below confirm the selective solubilization of PET and the effectiveness of the process developed to efficiently separate and thus valorize the PET contained from a stream of polymers in mixtures (thermoplastics + thermosets).

[0105] The IR analyses performed and shown in Figures 5a and 5b confirm qualitatively and semi-quantitatively the production of PET purified of any other thermoplastic and / or thermosetting material. A perfect overlap is observed between the IR spectra of the recycled polymer and the reference PET. There are no additional bands in the spectra confirming the absence of other polymers. The IR analyses therefore confirm the effectiveness of the process according to the invention. for the selective extraction of PET contained in this type of plastic waste and therefore its subsequent recovery.

[0106] The profiles of the ATG curves shown in Figures 2 and 6 are perfectly similar. Therefore, PET does not appear to be (qualitatively) modified in its thermal behavior after the implementation of the extraction process of the invention.

[0107] The gel permeation chromatography analyses shown in Figures 7a and 7b demonstrate that, qualitatively, the recovered PET exhibits an elution profile and molar mass distribution almost identical to that of the reference polymer. No additional peaks are identified, confirming the purity of the recycled sample.

[0108] Molar mass analyses (Table 2) reveal a slight degradation of the polymer chains, which lose between 6 and 10% of their molar mass depending on the molar mass indicator used (Mn, Mw, Mp, Mz). This value is more than twice as low as that for PET degradation by mechanical single recycling (26.4% loss for Mw).

[0109] [Tables2] Sample Mn (g / mol) Mw (g / mol) Mz (g / mol) IP Mp (g / mol) Area COBÇ. (mg / ml) Notes Reference PET 24435 52144 85232 2.1 41435 0.266 2.04 insoluble PET extracted in example 2 according to a process of the aventioû 21918 46770 78620 2.1 38734 0.174 L3 insoluble

[0110] Example 3 j. Recovery of 1 recyclable PET contained in a material from the grinding of automotive seat covers

[0111] In a 1.5 L double-jacketed glass reactor equipped with a drain / sip valve, a stainless steel filter basket (cut-off 60 µm), and a condenser, 50 g of ground automotive seat covers (containing, in particular, approximately 70% by mass of PET, 20% polyurethane foams, less than 10% polypropylene (PP), and less than 10% nylon 6 or nylon 66) are placed. 1-1.2 L of dimethyl isosorbide preheated to 200 °C is added to the basket. The double jacket has been preheated to 205 °C. The mixture is heated and stirred (mechanical stirring) at a temperature of 190 °C under an inert atmosphere (N2 flow) for a maximum of 45 minutes to allow the selective solubilization of the PET contained in the mixture. The solvent filtered through the basket and containing the dissolved PET is withdrawn and immediately added slowly to a second 2 L reactor containing 750 mL of dimethyl-isosorbide preheated to 120 °C and equipped with a stirring system.Mixing the two solutions results in the controlled precipitation of PET. The temperature. The final temperature of the additive is 137 °C. The solution is then stirred until the mixture temperature drops to 50 °C. The solution is centrifuged to separate the precipitated PET from the solvent. The solid is then washed with dimethyl isosorbide, followed by ethyl acetate. Finally, the solid is vacuum-dried at 120 °C for 24 hours and then characterized by TGA, IR, and GPC. Its crystallinity is determined by densimetry using a helium pycnometer. 29.22 g of PET were recovered at the end of the selective solubilization process of the supplied industrial waste.

[0112] The isolated PET is characterized by infrared IR (ATR-FTIR, using a SHIMADZU IRTracer-100), mass, GPC (Gel permeation chromatography: Waters 2695 system, hexafluoroisopropanol solvent, analysis temperature of 40 °C, a Waters 2414 refractive index detection module, calibration was carried out with narrow polymethyl methacrylate (PMMA) calibrators and TGA (NETZSCH STA 409 PC system) analyses.

[0113] The analyses presented below confirm the selective solubilization of PET and the effectiveness of the process developed to efficiently separate and thus valorize the PET contained from a stream of polymers in mixtures (thermoplastics + thermosets).

[0114] The IR analyses performed and shown in [Fig. 8a] and 8b qualitatively and semi-quantitatively confirm the production of PET purified of any other thermoplastic and / or thermosetting material. A perfect overlap is observed between the IR spectra of the recycled polymer and the reference PET. There are no additional bands in the spectra confirming the absence of other polymers. The IR analyses therefore confirm the effectiveness of the process according to the invention for the selective extraction of PET contained in this type of plastic waste and thus its subsequent recovery.

[0115] The profiles of the ATG curves shown in Figures 2 and 9 are perfectly similar. Therefore, PET does not appear to be (qualitatively) modified in its thermal behavior after the implementation of the extraction process of the invention.

[0116] Gel permeation chromatography (GC) analyses, shown in Figures 10a and 10b, demonstrate that the recovered PET has an elution profile and molar mass distribution almost identical to that of the reference polymer. No additional peaks are identified, confirming the purity of the sample obtained.

[0117] Molar mass analyses (Table 3) reveal a slight degradation of the polymer chains, which lose between 6 and 8.2% of their molar mass depending on the molar mass indicator used (Mn, Mw, Mp, Mz). This value is more than three times lower than that for PET degradation by mechanical single recycling (26.4% loss for Mw).

[0118] [Tables3] Sample Mn (g / mol) Mw (g / mol) Mz (g / mol) IP Mp (g / mol) CO1C Area (mg / mL) Notes Reference PET 79477 45224 72325 1.9 36461 0.276 2.2 N / A PET extracted in example 3 according to a process of the invention 21752 41509 66945 L9 34329 0.268 7 N / A

[0119] Characterization of the presence of residual trace amounts of solvent in recovered PET by gas chromatography-HRMS analysis

[0120] In a glass vial for microwave reactors capable of holding 2-5 mL of solvent, 500 mg of PET recycled by the process of the invention were mixed with 2 mL of acetonitrile or 2 mL of ethyl acetate. The tubes of both mixtures, after being sealed, were heated at 180 °C for 20 minutes using a microwave reactor (Biotage Initiator+ model). The operating parameters used were: pre-stirring = 10 seconds, absorption level = very high, stir rate = 300 rpm. The recovered solvent was filtered through a 0.2 µm PTFE cut-off microfilter and analyzed by GC-MS. The equipment used is an Agilent system consisting of the following parts: an Agilent 8890 GC system, an Agilent 7250 GC / Q-TOF mass system and an Agilent 7693A autosampler. The column used is a DB-WAX Ultra Inert (30 m x 0.250 mm x 0.25 pm).The solvent samples brought into contact with the PET recovered by the process of the invention were not diluted. The dimethyl isosorbide (DMI) sample was prepared by diluting 10 pL of DMI in 990 pL of ethyl acetate. The sample volume taken was 1 pL. The system is equipped with a split / splitless injector with a temperature of 250 °C. The split ratio used is 1 / 100. The helium flow rate in the column is maintained at 2 mL / minute.

[0121] The column furnace temperature program is as follows:

[0122] [Tables4] Speed ​​in °C / minutes Final temperature in °C Waiting time in minutes Analysis time in minutes Initial 50 1 1 Ramp 1 10 170 5 18 Ramp 2 10 250 5 31

[0123] The solvent delay is set at 3.26 minutes. The acquisition lasts 31 minutes. The samples are analyzed by positive electron impact (EI+). The flame ionization detector (FID) is set at a temperature of 250 °C with a H2 flow rate of 30 mL / minute and an air flow rate of 400 mL / minute. Under these conditions, the main peak of the DMI has a retention time of approximately 14.03 minutes.

[0124] Analysis of the two GC-MS samples of solvent in contact with PET recovered by the process of the invention (sample 1 and sample 2) shown in [Fig. 11] demonstrated, in comparison with the DMI sample, the presence of trace amounts of solvent in the recovered PET after drying. A peak in each chromatogram is present at t = 14.03 minutes, and the mass spectrum for this peak corresponds well to the spectrum of DMI, according to comparison with the NIST data library. The absence of a DMI peak in the chromatograms of the blanks (purges) before and after the measurements confirms that the detected DMI is not contamination of the GC-MS system by trace amounts of solvent. We can conclude that it is possible to trace the PET produced by the selective PET extraction recycling process presented here.

Claims

Demands

1. A process for extracting polyethylene terephthalate (PET) from a solid material containing it in a mixture with: - one or more additional thermoplastic materials selected from polyolefins, polyvinyl chloride (PVC), ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), elastanes, polyamides, elastomers, polyacetals, and mixtures thereof, and / or - one or more thermosetting materials selected from polyurethanes, epoxy resins, and mixtures thereof, - and optionally at least one metal, said process comprising at least the steps of: - Contacting said solid material in a reactor with a solvent selected from dimethyl isosorbide, benzyl acetate, and mixtures thereof, - Selectively solubilizing said polyethylene terephthalate by heating the mixture formed from said material and said solvent, under stirring and at a temperature ranging from 185 °C to 220 °C,- Isolate said mixture, said solvent containing the solubilized polyethylene terephthalate (PET), - Precipitate said polyethylene terephthalate in said isolated solvent, and - Recover the polyethylene terephthalate precipitate.

2. A process according to claim 1, wherein said solvent and said solid material to be treated are brought together in a weight ratio between said PET contained in said material and said solvent, PET / solvent, varying from 1:50 to 1:1 and in particular from 1:20 to 1:

5.

3. A method according to any one of the preceding claims, wherein the solubilization of said PET is carried out under an inert atmosphere, for example under nitrogen or argon, and under mechanical agitation.

4. A method according to any one of the preceding claims, wherein said solvent containing the solubilized polyethylene terephthalate is isolated by filtration.

5. A method according to any one of the preceding claims, wherein said solubilized polyethylene terephthalate is precipitated in said isolated solvent by cooling said solvent to a temperature below the solubilization temperature of PET, in particular by adding dimethyl isosorbide to said solvent, benzyl acetate or a mixture thereof, brought to a temperature such that the temperature of its mixture with said solvent containing the solubilized PET is less than 185 °C.

6. A method according to any one of the preceding claims, wherein said solid material is a mixture containing PET and at least one or more additional thermoplastics, in particular one or more polyethylenes, polypropylenes, polyvinyl chlorides, polyamides, one or more thermosets, in particular one or more polyurethanes, and cellulosic fibers (cotton, flax, hemp, silk).

7. A process according to any one of the preceding claims, wherein said solid material, when brought into contact with said solvent, is in the form of a grind having in particular a particle size ranging from 1 to 100 mm and in particular from 1 to 10 mm.

8. A process according to any one of the preceding claims, comprising prior to the step of bringing said solid material into contact with said solvent, at least one grinding step, in particular mechanical grinding.

9. A process according to the preceding claim comprising, between said grinding step and said contacting step, a sorting step dedicated to isolating one or more thermoplastic and / or thermosetting components of said ground material for its subsequent contact with said solvent.

10. A method according to any one of claims 8 or 9, wherein the grinding step comprises: - a step of shredding / crushing a source material into solid material to fragment it into a particle size ranging from 30 mm to 120 mm, and optionally - a subsequent step of granulating said fragments obtained.

11. A method according to the preceding claim, wherein said source material in solid material is a plastic waste containing PET, in particular a vehicle seat cover, a used vehicle seat cover and / or a production scrap thereof.

12. Use of a process according to any one of the preceding claims, for the selective extraction of PET contained in a vehicle seat cover, a used vehicle seat cover and / or production scrap thereof.

13. Recycled PET, in particular coloured, obtained by a process according to any one of claims 1 to 11.

14. Composition comprising recycled PET and a solvent selected from dimethyl isosorbide, benzyl acetate and mixtures thereof.

15. Composition according to claim 14, wherein the recycled PET is colored.

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