SOLID BIS(2-HYDROXYETHYL) TEREPHTHALATE EXHIBITING A PARTICULAR CRYSTALLINE FORM

Abstract

The present invention relates to a solid material composed mainly of BHET having a crystalline form exhibiting a particular X-ray diffraction pattern, its preparation process, a composition comprising said material, and the use of said composition to prepare a polyester. Figure to be published: Figure 4

Description

Title of the invention: SOLID BIS(2-HYDROXYETHYL) TE-REPHTHALATE PRESENTING A CRYSTALLINE FORM SPECIAL technical field

[0001] The invention relates to a solid material composed mainly of bis(2-hydroxyethyl) terephthalate (BHET), having a novel crystalline form. This crystalline form advantageously allows the solid material to be obtained in a needle-like morphology, thus facilitating its drying. The invention also relates to a composition comprising said solid material and the use of this composition to produce a polyester terephthalate, for example, polyethylene terephthalate (PET). Prior art

[0002] Bis(2-hydroxyethyl) terephthalate (BHET) is a monomer of terephthalate polyesters and in particular of polyethylene terephthalate (PET).

[0003] BHET can be obtained by direct esterification of terephthalic acid with ethylene glycol or transesterification between dimethyl terephthalate and ethylene glycol, methods classically corresponding to the first reaction step in conventional PET production processes. BHET can also be obtained by depolymerization of polyester, in particular polyethylene terephthalate (PET), in the presence of ethylene glycol. This is referred to as chemical recycling of polyester, particularly PET, since polyester waste, particularly PET, undergoes chemical treatment (depolymerization) to obtain a monomer compound that is then reused to produce polyester again, particularly PET and more specifically r-PET.

[0004] For example, French patent application FR 3053691 describes a process for depolymerizing a polyester filler comprising, in particular, 0.1 to 10 wt% pigments, by glycolysis in the presence of ethylene glycol. An effluent of bis-(2-hydroxyethyl) terephthalate (BHET) monomer, obtained after specific separation and purification steps, can feed a polymerization step for the production of PET. Japanese patent JP3715812 describes the production of refined BHET from PET, the resulting BHET being usable as a raw material in a process for the production of plastic products.

[0005] While they disclose the polymerization of monomeric products, in particular BHET, resulting from the depolymerization of PET by glycolysis, the cited documents nevertheless provide no information on the quality of the intermediate products resulting from the depolymerization of PET, nor on the difficulty of the purification steps in par- th. washing and drying of BHET-based intermediates.

[0006] However, the drying of BHET crystals is known to be problematic. For example, US patent 3,668,235 explains that the drying times of solid BHET are long, which impacts the quality of the BHET, notably through the appearance of coloration and a tendency for the crystals to agglomerate.

[0007] To facilitate drying and thus limit product degradation, it is important to reduce the drying time. The residual moisture content of the cake after filtration is a good indicator of how easily the cake can be dried, since drying will be easier when the amount of water to be removed is low.

[0008] A technique known to those skilled in the art for lowering the water content of a cake of a solid material is the use of centrifugal centrifuges for liquid / solid separation, which achieve residual moisture levels 2 to 3 times lower than simple filtration, the residual moisture corresponding to the balance between capillary forces and centrifugal forces (cf. M. Robatel et al., Centrifugation: Generalities, Theories, Engineering Techniques, A5550 VI, 1989, 10-17).

[0009] Patent application WO 2021 / 032826 indicates that the moisture content of the BHET crystal cake obtained by filtration is typically in the range of 20-50% by weight. This document therefore proposes granulating the BHET crystals to facilitate the drying of the solid, relying on the porosity of the granules to promote mass and heat transfer.

[0010] Furthermore, it is known that a needle-type morphology for crystals of a solid material allows for superior performance compared to other morphologies, for example the platelet morphology, in terms of filterability (cf. D. Bourcier et al., “Influence of particle size and shape properties on cake resistance and compressibility during pressure filtration”, Chemical Engineering Science, 2016, 144, 176-187).

[0011] Patent JP 5189266 confirms the effect of the needle-like morphology of BHET on the quality of BHET, and in particular on the residual solvent content of solid BHET obtained after crystallization and solid / liquid separation. However, this document provides no information regarding the crystalline form of the BHET obtained.

[0012] Miyaké's article (A. Miyaké, “Polymorphism of Bis-[3-hydroxyethyl Te-rephthalate”, Bulletin of the Chemical Society of Japan, 1957, 30(4), 361-363) discloses four crystalline forms of BHET: the alpha crystalline form, which appears to be the most stable, and the beta, gamma, and delta forms. However, this article provides no information regarding their macroscopic morphology and their properties, particularly filterability and / or ease of drying. According to the article by Alvarez-Castillo (A. Alvarez-Castillo et al., “Studies on the crystallization of polyethylene terphthalate oligomer”, Journal of Materials Science Letters, 14, 1995, 139-141), it would appear that the form BHET alpha crystalline can give a needle-like morphology to BHET crystals.

[0013] The present invention relates to high-quality BHET and, in particular, to BHET crystals having the lowest possible residual solvent and / or moisture content. Thus, the inventors have surprisingly discovered a new crystalline form of BHET which inevitably leads to a needle morphology and therefore to improved filterability and drying properties of the BHET crystals. Summary of the invention

[0014] The invention relates to a solid material composed mainly of BHET having a crystalline form exhibiting an X-ray Diffraction diagram with average values ​​of 20 and relative intensities Irei greater than or equal to 5%, as follows:

[0015] [Tables 1] 2 theta (°) Irel 10.85 ff 18.35 ff 19.17 FF 21.76 ff 29.19 ff 29.62 ff 38.82 ff 40.34 ff 49.18 ff

[0016] where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity Irei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction pattern: ff < 15; 15 <f <30 ; 30 < mf <50 ; 50 < m < 65 ; 65 < F < 85 ; FF >85.

[0017] The advantage of the present invention lies in the fact that the particular crystalline form facilitates the filterability and drying of the BHET. Indeed, the solid material according to the invention exhibits reduced residual moisture at the filtration outlet compared to other crystalline forms and is therefore easier to dry. Furthermore, the crystalline form of the solid BHET material according to the invention has a repeating structure that induces a needle-like morphology of the crystals, which allows for improved filterability and enhanced crystal washing.

[0018] Furthermore, another advantage of the present invention lies in the fact that the The particular crystalline form of BHET is stable, especially thermally stable.

[0019] Another advantage of the present invention lies in the origin of the BHET solid material and the compositions comprising it, since it can be obtained both by direct synthesis of BHET from terephthalic acid or dimethyl terephthalate and ethylene glycol, and also, advantageously, from plastic recycling programs established in recent years by national and international organizations to combat plastic pollution. Indeed, the BHET solid material of the present invention and the composition containing it can very advantageously be obtained from depolymerization processes by glycolysis of polyester such as PET, in the presence of a diol, including purification steps, notably a BHET crystallization step.The BHET resulting from these depolymerization processes is then called r-BHET, and the PET prepared by polymerization from r-BHET is called r-PET (as opposed to virgin PET or resin resulting from the direct polymerization of fresh terephthalic acid and ethylene glycol). Thus, the present invention contributes to the fight against plastic pollution.

[0020] The present invention therefore also relates to the use of the composition comprising the solid BHET material to prepare a polyester, preferably a PET. LIST OF FIGURES

[0021] [Fig.1]

[0022] Fig. 1 represents an image of solid A from Example 1, observed by optical microscopy.

[0023] [Fig.2]

[0024] Figure [Fig. 2] represents one of the solid B of Example 1, observed by optical microscopy.

[0025] [Fig.3]

[0026] Fig. 3 represents the XRD diagram obtained for solid A of Example 1.

[0027] [Fig.4]

[0028] Fig. 4 represents an XRD diagram of solid B of Example 1.

[0029] [Fig.5]

[0030] Fig. 5 represents an XRD diagram of solid C of Example 1.

[0031] [Fig.6]

[0032] Fig. 6 represents an XRD diagram of the solid D of Example 1. Description of the implementation methods

[0033] According to the invention, the terms "bis(2-hydroxyethyl) terephthalate" and "BHET" refer to the same compound and are interchangeable. Similarly, the terms "bis(2-hydroxyethyl) isophthalate" and "BHEI" refer to the same compound and are interchangeable. Interchangeable. The terms "2-(2-hydroxyethoxy) ethyl 2-hydroxyethyl te-rephthalate" and "BHET-deg" refer to the same compound and are also interchangeable.

[0034] According to the invention, the term "polyester" designates a thermoplastic polymer, advantageously saturated (as opposed to thermosetting polyesters), having diol diester repeating units, and more particularly at least alkylene terephthalate repeating units. The polymer chain may also include alkylene isophthalate and / or dialkyl terephthalate repeating units. Thus, according to the invention, the term "polyester" is used to designate poly(alkylene terephthalate) (or polyalkylene terephthalate, according to an anglicized term). The polyester according to the invention may, for example, be poly(ethylene terephthalate) (or polyethylene terephthalate, PET), poly(butylene terephthalate) (or polybutylene terephthalate, PBT), or poly(trimethylene terephthalate) (or polytrimethylene terephthalate, PTT).The polyester according to the invention may also include other motifs on its main polymer chain, such as vinyl or polyol motifs, depending on the desired final properties of the polymer and the intended applications. According to the invention, the preferred polyester is polyethylene terephthalate or poly(ethylene terephthalate), also simply called PET.

[0035] According to the invention, the terms "diol" and "glycol" are used interchangeably and refer to compounds comprising two hydroxyl groups (-OH) and preferably comprising between 2 and 12 carbon atoms, preferably between 2 and 4 carbon atoms. The preferred diol is ethylene glycol, also called monoethylene glycol or MEG.

[0036] Crystals are solids in which atoms, ions, or molecules are arranged in three-dimensional space by periodically repeating a structure. The crystalline form corresponds to the description of this repeating structure. A solid can exist in different crystalline forms: this is called polymorphism. In a crystallization process, obtaining one form rather than another is determined by the choice of solvent and / or by the conduct of the crystallization process. Each form is generally characterized by X-ray diffractometric analysis (XRD). The set of peaks in a diffractogram obtained by XRD, in particular their positions and preferably also their intensities, characterizes the crystalline form. In the case of BHET, four crystalline forms are known: alpha, beta, gamma, and delta forms (see A.Miyaké, “Polymorphism of Bis-[3-hydroxyethyl Te-rephthalate”, Bulletin of the Chemical Society of Japan, 1957, 30(4), 361-363). .

[0037] According to the present invention, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this is not the case and the values limits are not included in the range described, such precision will be provided by the present invention.

[0038] In the sense of the present invention, 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 the sense of the present invention, a preferred pressure range can be combined with a more preferred temperature range.

[0039] In the following, particular embodiments of the invention may be described. They may be implemented separately or in combination with each other, without limitation of combinations where technically feasible.

[0040] According to the invention, the pressures are absolute pressures and are given in MPa.

[0041] The invention thus relates to a solid material composed mainly of BHET, preferably comprising BHET at a weight content greater than or equal to 50%, preferably greater than or equal to 70%, preferably greater than or equal to 90%, most preferably greater than or equal to 95%, preferably greater than or equal to 98%, or even greater than or equal to 99% (the percentages are relative to the total weight of the dry material, i.e. excluding moisture or other solvent, for example, used during the process of preparing such a solid and in particular during the crystallization step such as ethylene glycol or methanol or a glycol ether), having a crystalline form exhibiting an X-ray diffraction pattern (or XRD pattern) with average values ​​of 20 and relative intensities Irei greater than or equal to 5%, as follows:

[0042] [Tables 1] 2 theta (°) Irel 10.85 ff 18.35 ff 19.17 FF 21.76 ff 29.19 ff 29.62 ff 38.82 ff 40.34 ff 49.18 ff

[0043] where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity Irei is given in relation to a relative intensity scale where A value of 100 is assigned to the most intense line in the X-ray diffraction pattern: ff < 15; 15 <f <30 ; 30 < mf <50 ; 50 < m < 65 ; 65 < F < 85 ; FF >85.

[0044] The solid material composed mainly of BHET according to the invention may also be called BHET material or solid BHET, in the rest of this description.

[0045] According to a particular embodiment of the invention, the solid material, which is composed mainly of BHET having the crystalline form whose XRD diagram is shown in Table 1, exhibits a single crystalline form. In other words, it only exhibits the crystalline form with the X-ray diffraction pattern whose average values ​​of 20 and relative intensities are given in Table 1. Preferably, the BHET material, which has a single crystalline form, that whose XRD diagram is shown in Table 1, does not exhibit an amorphous form.

[0046] According to another particular embodiment of the invention, the solid material is composed mainly of BHET, which has the crystalline form exhibiting the X-ray diffraction pattern represented by the values ​​of 20 and relative intensities, greater than or equal to 5%, of Table 1, and of another crystalline form of BHET, preferably chosen from the alpha, beta, delta, gamma forms of BHET and a combination of at least two of these crystalline forms. The XRD patterns of the alpha, beta, delta, gamma forms of BHET are shown in [Fig. 1] and were determined by Miyaké's team (A. Miyaké, “Polymorphism of Bis-[3-hydroxyethyl Terephthalate”, Bulletin of the Chemical Society of Japan, 1957, 30(4), 361-363). According to this particular embodiment of the invention, the BHET material can also have an amorphous form.Preferably, the BHET material in this particular embodiment does not include any amorphous shape.

[0047] According to the invention, X-ray diffraction (XRD) analysis performed on the BHET material makes it possible to verify the presence of the crystalline form(s) of BHET. According to the invention, the solid BHET material exhibits an X-ray diffraction pattern including at least the lines listed in Table 1. Preferably, the X-ray diffraction pattern does not contain any other lines of significant intensity (i.e., with an intensity greater than or equal to 5% of the intensity of the most intense line in the XRD pattern) than those listed in Table 1. For those skilled in the art, the essential characteristic of an XRD pattern is the position of the peaks (values ​​of 2θ); relative intensities are often given for informational purposes only.

[0048] The X-ray diffraction pattern (or XRD pattern) is obtained by X-ray crystallographic analysis using a diffractometer with the classical powder method and copper Kai radiation (X = 1.5406 Å). The position The diffraction peaks (or lines) are represented by the angle 20°. An absolute error A(20°), assigned to the measurement of 20°, equal to ±0.1° is commonly accepted. The relative intensity Irei assigned to each value of dhki is measured from the height of the corresponding diffraction peak (or line). The X-ray diffraction pattern of the solid material comprising mainly BHET according to the invention includes at least the lines given in Table 1.

[0049] Most advantageously, the solid material according to the invention is in the form of needles.

[0050] The present invention also relates to a composition comprising the material BHET according to the invention. Preferably, the composition comprising the BHET material according to the invention is in solid or liquid form (i.e., a composition that is macroscopically in liquid form, for example, a suspension or a slurry being compositions in liquid form), and more particularly in solid form, as a slurry, or as a suspension of solid particles of the BHET material according to the invention suspended in a solvent. The composition comprising the BHET material according to the invention can therefore be in solid or liquid form (suspension or slurry) and further comprise a solvent, preferably selected from an aqueous solvent, in particular water, an alcoholic solvent, for example methanol or a diol such as ethylene glycol, or a solvent composed of a mono- or di-ether of glycol; preferably the solvent is water.

[0051] According to a particular embodiment of the invention, the composition comprising the BHET material according to the invention is a solid composition and further comprises a solvent, preferably with a content less than or equal to 20% by weight, preferably less than or equal to 15% by weight, preferably less than or equal to 10.0% by weight and more particularly less than or equal to 5.0% by weight, or even less than or equal to 1.0% by weight.

[0052] According to another particular embodiment of the invention, the composition comprising the BHET material according to the invention is a composition in liquid form, more particularly a slurry or suspension type composition, which comprises a solvent and solid particles of the BHET material according to the invention, preferably between 1 and 75% by weight, preferably between 5 and 45% by weight, most preferably between 15 and 35% by weight of solid material according to the invention.

[0053] Advantageously, the composition according to the invention can be obtained by, preferably obtained by, a process for treating a polyester filler, preferably comprising PET, which includes a step of depolymerizing the polyester filler, in particular the PET it contains, and preferably followed by at least one separation-purification step. The depolymerization step can implement depolymerization by glycolysis in the presence of ethylene glycol or by methanolysis in the presence of methanol. In the latter case, an additional step of Transesterification in the presence of ethylene glycol is then necessary. Preferably, the depolymerization step implements depolymerization by glycolysis in the presence of ethylene glycol. The process for treating a polyester filler, preferably containing PET, may, for example, include, as a purification step of the effluent obtained by depolymerization of the polyester filler, in particular a step of crystallizing BHET in water, in ethylene glycol, or in a mono- or di-glycol ether, preferably in water.

[0054] According to a particular embodiment of the invention, the composition according to the invention may further comprise bis(2-hydroxyethyl)isophthalate (BHEI), preferably in a molar quantity such that the molar ratio (BHEI / [BHET + BHEI]) of the number of moles of BHEI to the number of moles of the combined BHET and BHEI present in the composition is less than or equal to 10.0 mol%, preferably less than or equal to 5.0 mol%, preferably less than or equal to 1.0 mol%, and preferably less than or equal to 0.5 mol%. Furthermore, if the composition comprises BHEI, the molar ratio (BHEI / [BHET + BHEI]) is greater than or equal to 0.001 mol%, preferably greater than or equal to 0.01 mol%, and preferably greater than or equal to 0.05 mol%.

[0055] According to another particular embodiment of the invention, the BHET-based composition according to the invention may further comprise 2-(2-hydroxyethoxy)ethyl 2-hydroxyethyl terephthalate (BHET-deg), preferably in a molar quantity such that the molar ratio (BHET-deg / [BHET + BHET-deg]) between the number of moles of BHET-deg and the number of moles of the whole BHET and BHET-deg present in the composition is less than or equal to 10.0 molar percent, preferably less than or equal to 5.0 molar percent, preferably less than or equal to 1.0 molar percent. Furthermore, if the composition includes BHET-deg, the molar ratio (BHET-deg / [BHET + BHET-deg]) is greater than or equal to 0.001 molar%, preferably greater than or equal to 0.05 molar%, preferably greater than or equal to 0.10 molar%, preferably greater than or equal to 0.50 molar%.

[0056] One or both of these particular embodiments of the invention may possibly be the case(s) of products obtained at the end of polyester filler processing, which include a depolymerization step.

[0057] The present invention thus relates to a method for preparing a composition according to the invention comprising:

[0058] - a depolymerization step of a polyester filler, preferably comprising PET, employing depolymerization by glycolysis in the presence of ethylene glycol or by methanolysis in the presence of methanol, preferably, depolymerization by glycolysis in the presence of ethylene glycol; then

[0059] - at least one purification step, preferably comprising a crystallization step lization in water, in ethylene glycol, or in a mono- or di-ether of glycol, preferably in water.

[0060] Most advantageously, the preparation process comprises, consists of, the depolymerization process described in patent FR 3053691, the decolorization step of which includes an adsorption step and may further include a purification step by crystallization of BHET in water, in ethylene glycol, or in a mono- or di-ether of glycol, preferably in water.

[0061] The BHET material according to the invention, which has the particular crystalline form whose XRD diagram is shown in Table 1, advantageously allows for the filtration and drying of the composition according to the invention containing it and obtained after such a preparation process. Since these filtration and drying steps are facilitated, the solid according to the invention, obtained after such steps, advantageously comprises a reduced residual solvent content, in particular a reduced residual moisture content, which allows it to be used in a polymerization step without additional energy-intensive treatment.

[0062] The composition comprising the BHET material according to the invention makes it very advantageous to obtain, after polymerization, a polyester, preferably a PET, and in particular an r-PET exhibiting a light or even colorless colour.

[0063] Thus the invention also relates to the use of the composition according to the invention, optionally mixed with at least one dicarboxylic acid, preferably chosen from terephthalic acid and isophthalic acid, and / or at least one diol, preferably chosen from ethylene glycol, diethylene glycol, butylene glycol, cyclohexane dimethanol, neopentyl glycol or mixtures thereof, the preferred diol being ethylene glycol, to prepare a polyester, preferably a PET.

[0064] The invention therefore also relates to a method for producing a polyester, preferably comprising:

[0065] a) an esterification step of a charge comprising at least the composition according to the invention, and optionally at least one dicarboxylic acid, preferably selected from terephthalic acid and isophthalic acid, and / or at least one diol, preferably selected from ethylene glycol, diethylene glycol, butylene glycol, cyclohexane dimethanol, neopentyl glycol or mixtures thereof, the preferred diol being ethylene glycol; then

[0066] b) a polycondensation step.

[0067] Advantageously, step a) is carried out at a temperature between 150 and 350°C, preferably between 200 and 300°C, and more preferably between 250 and 285°C. Preferably, step a) is carried out at a pressure between 0.05 and 1.0 MPa, and more preferably between 0.1 and 0.5 MPa. Most advantageously, step a) is carried out with a residence time between 0.5 and 10.0 hours, and more preferably between 1.0 and 6.0 hours. residence time is defined here as the ratio of the reaction volume of a reactor implemented in step a) to the volumetric flow rate of the liquid flow exiting said reactor.

[0068] A polymerization catalyst, preferably based on antimony, titanium, germanium, aluminum, zinc acetate, calcium acetate and / or manganese acetate, may optionally be introduced in step a).

[0069] The reaction carried out in step a) generates a diol compound which is advantageously separated during step a), for example by drawing off, distillation and / or adsorption. Water may also be formed. The water then formed is also advantageously separated during step a).

[0070] Advantageously, the process for producing a polyester according to the invention includes a polycondensation step b) following step a). Step b) may advantageously implement one or more, preferably one or two, polycondensation substep(s), for example at least, preferably one, a liquid or molten phase polycondensation substep, possibly followed by at least one, preferably one, solid phase polycondensation substep.

[0071] Most advantageously, step b) of polycondensation employs at least one polymerization section, preferably one or two polymerization sections, advantageously operated in liquid or molten phase, said (or said) polymerization section(s) being carried out at a temperature higher than the temperature at which step a) is carried out, preferably at a temperature between 190 and 400°C, preferably between 220 and 350°C, preferably between 265 and 300°C, preferably at a pressure between 0.01 and 100.00 kPa, preferably between 0.05 and 10.00 kPa, and preferably with a residence time between 0.1 and 5.0 hours, preferably between 0.5 and 4 hours, preferably between 1.0 and 3.0 hours.The residence time in the polymerization section of step b) is defined as the ratio of the reaction volume of a reactor implemented in said polymerization section to the volumetric flow rate of the liquid stream, including the polyester produced, exiting said reactor.

[0072] The polymerization reaction may optionally be continued in a polycondensation section located downstream of the polymerization section and operated in the solid phase, preferably at a temperature (in particular a product temperature) between 190 and 250°C, preferably between 200 and 230°C. This depends on whether the operation is carried out in continuous or batch mode. The polycondensation section may preferably be operated under an inert atmosphere, for example under a nitrogen flow at a pressure close to atmospheric pressure, or under vacuum (in particular at a pressure between 0.01 and 100 kPa, or even between 0.01 and 10 kPa). The residence time (defined as the time during which the product is subjected to the polycondensation conditions in said polycondensation section) is between 5 and 20 hours, preferably between 10 and 16 hours. Said polycondensation section may advantageously be preceded by a crystallization section, thus situated between the polymerization section and the polycondensation section, in which the polyester formed, obtained at the end of the polymerization section, is advantageously crystallized, said crystallization section being able to operate at a temperature preferably between 110 and 210°C, and for a residence time (defined as the time during which the product is subjected to the crystallization conditions in said section) preferably between 0.5 and 6 hours.

[0073] Step b) is preferably carried out in the presence of a polymerization catalyst, in particular based on antimony, titanium, germanium, aluminum, zinc acetate, calcium acetate and / or manganese acetate.

[0074] Additives may be introduced in step b) of polycondensation. The additives possibly introduced in step b) may be, for example: agents for inhibiting secondary etherification reactions, such as amines (n-butylamine, diisopropylamine or triethylamine), sodium hydroxide or organic hydroxides or lithium carbonate, stabilizing agents such as phosphites or phosphates, and polyamide-type compounds to reduce the amount of degradation product such as acetaldehyde.

[0075] The following figures and examples illustrate the invention without limiting its scope. EXAMPLES

[0076] Example 1: Solids

[0077] Two solids, solid A and solid B, obtained from the glycolysis depolymerization of PET waste and purification by crystallization in water (gradual temperature decrease from 60°C to 20°C), are recovered after filtration. The recovered solids A and B comprise at least 98.5% BHET by weight relative to their dry solid weight. A fraction of solid B is then oven-dried at 30°C for 15 hours to obtain solid C. A fraction of solid C is then placed at 60°C for 15 hours to obtain solid D.

[0078] Solids A and B were observed by optical microscopy. Photographs of these observations are shown in Figures 1 and 2 for solids A and B respectively.

[0079] The solid A has a platelet-type morphology ([Fig. 1]).

[0080] The solid B has a needle-like morphology ([Fig.2]).

[0081] The XRD patterns of solids A, B, C, and D are determined by X-ray crystallographic analysis using a diffractometer with the classical powder method and copper Kal radiation (X = 1.5406 Å). The position of the diffraction peaks (or lines) is represented by the angle 20 measured with an absolute error A(20) equal to ± 0.1°. The relative intensity Irel is measured from the peak height (or corresponding diffraction line. The XRD diagrams of solids A, B, C and D are shown in Figures 3, 4, 5 and 6 respectively, and presented in Table 2 below.

[0082] [Tables2] Solid A Solid 8 Solid C Solid D 2 theta H ff 2 theta f) h. 2 theta HU; 2 theta 0 w 6.65 10.80 f 10.87 ff 10.30 f 6.92 FF 11.13 ff 11.20 ff 13.87 ff 14.31 Ff 23.37 ff 18.29 ff 18.39 ff 18.39 Ff 35.16 18.55 ff 18.62 ff 19.12 FF 19.19 FF 19.19 FF 21.73 ff 21.75 ff 21 75 Ff 29-.15 f 29.21 f 29.21 F 29.55 ff 29.65 ff 29.65 Ff 38.77 ff 38.84 ff 38.84 Ff 40.28 ff ff 40.28 Ff 49.13 ff 49.20 ff 49.20 Ff

[0083] where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity Irei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction pattern: ff < 15; 15 <f <30 ; 30 < mf <50 ; 50 < m < 65 ; 65 < F < 85 ; FF >85.

[0084] The solid A corresponds to the shape a.

[0085] Solids B, C and D correspond to the crystalline form according to the invention. According to the XRD diagrams, it appears that the crystalline form according to the invention is stable since the XRD diagrams of solids C (drying of the solid at 30°C for 15 hours) and D (drying of the solid at 30°C for 15 hours then at 60°C for 15 hours) are not or only slightly modified compared to that of solid B.

[0086] Example 2: Centrifugal dewatering of solids E (non-conforming) and F (conforming to the invention)

[0087] Solids E and F, obtained by crystallizing BHET solutions in water by progressively lowering the temperature from 60°C to 20°C for 4 and 6 hours respectively, and recovered after filtration, comprise at least 98.5% BHET by weight relative to their dry solid weight. They are observed under an optical microscope and their XRD pattern is determined according to the same method as that detailed in Example 1.

[0088] The solid E has a platelet-type morphology and exhibits a crystalline- graph a.

[0089] The solid F has a needle-like morphology and exhibits a crystallographic shape according to the invention.

[0090] Each of the solids E and F undergoes a water wash such that each mixture is a suspension of 20% weight of solid in 80% weight of water, then a solid-liquid separation by centrifugal spinning at 20°C.

[0091] The residual water content of each solid after washing is determined by the mass loss of the solids after oven drying at 40°C under vacuum for 15 hours.

[0092] Table 3 presents the results obtained for the two solids E and F.

[0093] [Tables3] Solid E Solid F BHET content (%) 98.5 98.5 Crystalline form a according to the invention Residual moisture after centrifugal dewatering (%) 26 10

[0094] The results show that solid F, with a crystalline form according to the invention and a needle-like shape, achieves a significantly lower residual moisture content (10%) than solid E, which has a crystalline form a and a plate-like shape. Solid F will therefore be much easier to dry compared to solid E because there is less water to remove.

Claims

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3.

4.

5. Demands Solid material composed mainly of BHET having a crystalline form exhibiting an X-ray Diffraction diagram with average values ​​of 20 and relative intensities Irei greater than or equal to 5%, as follows: [Table 1] 2 theta (°) Lel 10.85 ff 18.35 ff 19.17 FF 21.76 ff 29.19 ff 29.62 ff 38.82 ff 40.34 ff 49.18 ff where FF = very strong; F = strong; m = medium; mf = medium-weak; f = weak; ff = very weak. The relative intensity Irei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction pattern: ff < 15; 15 <f <30 ; 30 < mf <50 ; 50 < m < 65 ; 65 < F < 85 ; FF >85. Material according to claim 1, having a single crystalline form. Material according to claim 1, having the crystalline form exhibiting the X-ray Diffraction diagram represented by the values ​​of 20 and relative intensities of Table 1 and another crystalline form, preferably selected from the alpha form, the beta form, the delta form, the gamma form of BHET and a combination of at least two of these crystalline forms. Material according to any one of the preceding claims comprising BHET having said crystalline form, in a weight content greater than or equal to 90%, preferably greater than or equal to 95%, preferably greater than or equal to 98%, the percentages being given in relation to the total weight of the dry material. Material according to any one of the preceding claims, in the form needles.

6. Solid or liquid composition comprising the material according to any one of the preceding claims.

7. Composition according to claim 6, further comprising a solvent, preferably an aqueous solvent, an alcoholic solvent, for example methanol, or a diol, or a mono- or di-ether of glycol, the preferred solvent being water.

8. Solid composition according to claim 6 or 7, further comprising a solvent, and preferably with a weight content less than or equal to 20% by weight, preferably less than or equal to 15% by weight.

9. Composition according to any one of claims 6 to 8 capable of being obtained by a process of processing a polyester filler, preferably comprising PET, which includes a depolymerization step by glycolysis in the presence of ethylene glycol, and preferably followed by at least one purification and / or separation step, for example comprising a crystallization step of BHET, in particular in water.

10. A process for preparing a composition according to any one of claims 6 to 9, comprising: - a step of depolymerizing a polyester filler, preferably comprising PET, implementing depolymerization by glycolysis in the presence of ethylene glycol or by methanolysis in the presence of methanol, preferably depolymerization by glycolysis in the presence of ethylene glycol; then - at least one purification step, preferably comprising a crystallization step in water, in ethylene glycol, or in a mono- or di-ether of glycol, preferably in water.

11. Use of the composition according to any one of claims 6 to 9, to prepare a polyester, preferably a PET.

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