Depolymerization of mixed polyester waste streams and recovery of monomer fractions

Abstract

A first aspect of the invention relates to a process for recycling a mixture of polyesters, wherein the mixture of polyesters comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester. In a second aspect, the invention is directed to the one or more monomer(s) obtained or obtainable from the process according to the first aspect of the invention, wherein a third aspect of the invention is directed to the use of these one or more monomer(s) of the second aspect of the invention for polymer synthesis. A fourth aspect of the invention relates to a method for preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester from the one or more monomer(s) of the second aspect of the invention. A fifth aspect of the invention is directed to a process comprising the step of converting the one or more monomer(s) of the second aspect of the invention and / or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to the first aspect of the invention, to obtain a product PRF1.

Description

241087W001Depolymerization of mixed polyester waste streams and recovery of monomer fractionsA first aspect of the invention relates to a process for recycling a mixture of polyesters, wherein the mixture of polyesters comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester. In a second aspect, the invention is directed to the one or more monomer(s) obtained or obtainable from the process according to the first aspect of the invention, wherein a third aspect of the invention is directed to the use of these one or more monomer(s) of the second aspect of the invention for polymer synthesis. A fourth aspect of the invention relates to a method for preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester from the one or more monomer(s) of the second aspect of the invention. A fifth aspect of the invention is directed to a process comprising the step of converting the one or more monomer(s) of the second aspect of the invention and / or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to the first aspect of the invention, to obtain a product PRF1.Polymer recycling is a topic of outmost importance, especially in a sustainability-driven society. The ongoing depletion of oil and the environmental demands on the one hand and the always increasing demand for polymeric products make the search for recycling methods essential. Recycling of pure polymeric materials, i.e. materials consisting of only one kind of polymer is a well investigated area. For example, C. Shen et al. describes a process for the alkaline hydrolysis of pure polybutylene adipate terephthalate (PBAT) (Chengfeng Shen, Xue Zhao, Yuwei Long, Wenli An, Xuelian Zhou, Xuehui Liu, Shimei Xu, and Yu-Zhong Wang, ACS Sustainable Chem. Eng. 2023, 11,2005-2013). Even if recycling processes for pure polymers are known in the art, their application range is limited since in these times, polymers are mostly present in mixtures of two or more different polymers, this making any recycling process very demanding. Biodegradable polymers are often falsely disposed in recycling streams instead of compost streams, leading to a contamination of otherwise established recycling procedures. Since separation of such mixed waste fractions by established methods such as near infrared (NIR) sorting shows limited performance when it comes to chemically similar polymers such as different polyesters, it will be required to established robust processes that are able to handle such difficult streams.Regarding polymeric mixtures, J. S. DesVeaux et al. discloses a mixed polyester recycling, however, only by meth-anolysis, glycolysis, and acid hydrolysis, wherein methanolysis is suggested as the tool of choice (Jason S.DesVeaux, Taylor Uekert, Julia B. Curley, Hoon Choi, Yuanzhe Liang, Avantika Singh, Ofei D. Mante, Gregg T. Beckham, Alan J. Jacobsen, and Katrina M. Knauer, 2024, One Earth 7, 2204—2222;https: / / doi.org / 10.1016 / j .oneear.2024.11.007). However, only overall yields of only 65 weight-% are achieved therewith at best and the methanolysis has several drawbacks in view of complexity of the overall process as well as that, for example, catalysts such as dimethylethylamine have to be used. Thus, there is still a need for providing methods, which allow for higher yields as optimum monomer recovery is essential.The objective technical problem was thus the provision of an improved recycling process for mixtures of polymers, which overcomes the above-mentioned drawbacks.241087W001-2 -1staspect - Process for recycling a mixture of polyestersAccording to a first aspect of the invention, the problem is solved by a process for recycling a mixture of polyesters, wherein the mixture of polyesters comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester, the process comprising:(a) providing a mixture of polyesters which comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester;(b) contacting the mixture of polyesters of (a) with a mixture of water and at least one 01 to C5 alkanol, which comprises at least 1 equivalent of at least one (earth) alkali metal hydroxide per ester unit of all polyesters of the mixture of (a), at a temperature T<bj in the range of from >110°C to < 200 °C; thereby obtaining a dispersion;(c) reducing the temperature of the dispersion obtained in (b) from temperature T<bj to a temperature T<C), with T<C) < T(b), thereby obtaining a solid phase and a liquid phase, wherein the solid phase comprises an (earth) alkali metal salt of aromatic diacidand optionally one or more (earth) alkali metal salt(s) of diacid(s) from the biodegradable polyester; and the liquid phase comprises water, 01 to C5 alkanol, alkylene glycol, optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester, and optionally one or more diol(s) from the biodegradable polyester.It is known that biodegradable polyesters such as PBAT can be hydrolyzed under alkaline conditions, wherein the alkaline hydrolysis has to be carried out carefully at temperatures of about 80°C (see C. Shen et al.). At higher temperatures, a degradation of such biodegradable polyesters is expected. On the other hand, polyalkylene aromatic diacid based polyesters such as PET are known to be hydrolysable under alkaline conditions, wherein high temperatures of more than 200°C are required in order to achieve a sufficient hydrolysis (see B. Raheem et al., Journal of Cleaner Production, 225 (2019), 1052-1064). Thus, these conditions have been considered as incompatible. It has now been surprisingly found that a mixture of the biodegradable polyester such as PBAT, and a polyalkylene aromatic diacid based polyester, such as PET, can be hydrolyzed under alkaline conditions in a specific temperature window in the range of from >110°C to < 200 °C, wherein the momomeric units of polyalkylene aromatic diacid based polyesters such as PET as well as the momomeric units of biodegradable polyester such as PBAT can be recovered in almost quantitative yield without loss due to monomer degradation or due to non-hydrolysis.The dispersion obtained in step (b) comprises water, C1 to C5 alkanol, (earth) alkali metal salt of aromatic diacid, optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester, optionally one or more (earth) alkali metal salt(s) of diacid(s) from the biodegradable polyester, alkylene glycol, optionally one or more alkali metal salt(s) of monoacid(s) from the biodegradable polyester and optionally one or more diol(s) from the bio-241087W001- 3 -degradable polyester. Thus, all polyesters present in the mixture of polyesters provided in step (a), i.e. all biodegradable polyesters and all polyalkylene aromatic diacid based polyesters, are at least partially hydrolyzed in step (b), preferably at least 80 weight-%, more preferably at least 85 weight-%, more preferably at least 90 weight-% of the biodegradable polyesters and polyalkylene aromatic diacid based polyesters are hydrolyzed in step (b), wherein the weight of the sum of all biodegradable polyesters and polyalkylene aromatic diacid based polyesters represents 100 weight-%. The dispersion obtained in step (b) is in some embodiments a suspension, wherein the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) from the biodegradable polyester are at least partially already present in solid form but remain dispersed in the liquid phase. Residues of other polymers such as polyolefins, which might be present in the mixture of polyesters comprising at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester, will remain undissolved and constitute a solid residue. Further solid matter would remain if the mixture of polyesters comprising at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester comprises solids such as glass, wood etc.. If such solid residues remain after step (b), the dispersion obtained in (b) has to be separated therefrom by a suitable physical separation method such as filtration. These further potential solids (from polyolefins and / or glass, wood etc.) are also part of the solid phase obtained in step c) and will herein below be summarized also as "solid remainder”.Preferably, the process comprises:(d) separation of the solid phase and the liquid phase obtained in (c), more preferably by a physical separation method, wherein separation is done at temperature T<d), wherein T<d) is preferably the same temperature as T(C), thereby obtaining a separated solid phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more alkali metal salt(s) of diacid(s) from the biodegradable polyester; and a separated liquid phase comprising water, C1 to C5 alkanol, alkylene glycol, optionally one or more diol(s) from the biodegradable polyester, and optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester.Preferably, the process comprises:(e) contacting the separated solid phase obtained in (d) with an aqueous agent, more preferably water, at a temperature T(e) > 20°C, thereby obtaining a liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form and optionally a solid remainder.Preferably, step (e) comprises:(e.1) washing the separated solid phase obtained in (d) with a C1 to C5 alkanol, more preferably at a temperature T(e.i) with T(e.i) = T(d) = T(C>; thereby obtaining a washed separated solid phase;241087W001-4-(e.2) contacting the washed separated solid phase obtained in (e.1) with an aqueous agent, more preferably water, at a temperature T<e) > 20°C, thereby obtaining a liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form and optionally a solid remainder.Preferably, the process comprises:(f) optionally separating the liquid aqueous phase obtained in (e) or in (e.2) from the solid remainder obtained in (e) or in (e.2), more preferably by a physical separation method; thereby obtaining a separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form.Preferably, the process comprises:(g) adjusting the pH value of the separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form obtained in (e), (e.2) or (f), more preferably by addition of an inorganic acid and / or by an electrochemical method, to a pH value < 7, preferably a pH value in the range of from 3 to 6.9, more preferably in the range of from 5.5 to 6.5, thereby obtaining an aqueous mixture, the aqueous mixture comprising a precipitate comprising aromatic diacid and optionally at least parts of one or more diacid(s) and a liquid aqueous part.Preferably, the process comprises:(h) separating the precipitate formed in step (g) from the liquid aqueous part mixture at a temperature T<h> >70°C by a physical separation method, optionally including one or more washing steps at T<h), thereby obtaining a separated liquid aqueous phase, which comprises the one or more diacid(s), and a separated solid remainder, which comprises the aromatic diacid.The (earth) alkali metal salt of aromatic diacid obtained from step (f), or the aromatic diacid obtained from step (h) if diacid(s) from the biodegradable polyester are present, is purified by known methods, for example by dissolution in a suitable solvent, optionally with a base for pH adjustment (for example aqueous solution of sodium hydroxide in case of aromatic diacid), optionally followed by filtration, contacting with activated charcoal and removal of said activated charcoal by filtration, followed by pH adjustment by acid addition for precipitation of the aromatic diacid. The precipitated aromatic diacid is optionally separated by filtration, washed with water and dried. Alternatively or in addition, a recrystallization can be done from a suitable solvent such as dimethylacetamide (DMAC) at a suitable temperature (see, for example, J. Slapnik et al., Conference Paper ■ September 2019 DOI: 10.5281 / zenodo.3430180). Further purification methods for aromatic diacids such as terephthalic acid are known, for example, by using adsorption columns, which are especially suitable for (earth) alkali metal salts of aromatic diacids such as (earth) alkali metal terephthalates. Purity of aromatic diacids such as terephthalic acid is determinable by known methods, for example, as241087W001- 5-presented in ASTM D7976-14(2020) standard or by determination of optical density at 340 nm (OD340) or transmittance at 340 nm of a solution of the aromatic diacid, for example, terephthalic acid, is measured by UV-VIS spectroscopy (see, for example, US 5679847 A1).Preferably, the process comprises:(I) Adjusting the temperature of the aqueous liquid phase, which comprises the one or more diacid(s), obtained in (h), to a temperature T(i) < 10°C, thereby obtaining the one or more diacid(s) in solid form (crystallization).The one or more diacid(s) such as adipic acid can be further purified by methods known to the skilled person, such as crystallization or recrystallization, for example crystallization or recrystallization in at least one carboxylic acid (see, for example, US 6,538,156 B1 ) or, for example, crystallization comprising modifying the crystal morphology (see, for example, US 5,296,639 A). Purity of diacid(s) such as adipic acid can be determined by methods known in the art, for example, gas chromatography.Preferably, the process comprises:(x) adjusting the pH value of the separated liquid phase comprising water, C1 to C5 alkanol, alkylene glycol, optionally one or more diol(s) from the biodegradable polyester, and optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester obtained in (d) to a pH value < 7, and adding an earth alkali metal salt, preferably CaCOa, thereby optionally obtaining a solid residue comprising one or more earth alkali metal salt(s), preferably calcium salt(s), of monoacid(s) from the biodegradable polyester and a liquid phase comprising water, C1 to C5 alkanol, alkylene glycol and optionally one or more diol(s) from the biodegradable polyester;(y) separation of the liquid phase obtained in (x) by distillation and / or liquid / liquid extraction, thereby obtaining a fraction comprising alkylene glycol, a fraction comprising C1 to C5 alkanol and optionally a fraction comprising one or more diol(s) from the biodegradable polyester.The fraction comprising C1 to C5 alkanol obtained in (y) can be recycled, partially or totally, to step (b) of the inventive process. The liquid phase obtained in (x) can optionally also be recycled to step (b) of the inventive process.Preferably, the process comprises:(z) contacting the solid residue comprising one or more earth alkali metal salt(s), more preferably calcium salt(s), of monoacid(s) from the biodegradable polyester, obtained from step (x) with an inorganic acid, preferably selected from the group consisting of H2SO4, HCI, H3PO4, and mixtures of two or more of these inorganic acids, thereby obtaining the monoacid(s).biodegradable polyester241087W001- 6 -Preferably, the at least one biodegradable polyester is selected from the group consisting of polybutylene adipate terephthalate (PBAT), poly (butylene sebacate-co-terephthalate) (PBSeT), polylactid acid (PLA), and mixtures of two or more of these polyesters, and more preferably comprises at least PBAT.polyalkylene aromatic diacid based polyesterPreferably, the at least one polyalkylene aromatic diacid based polyester is selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene furan-2,5-dicarboxylate (PEF) and mixtures of two or more thereof, more preferably the at least one polyalkylene aromatic diacid based polyester is at least one polyalkylene terephthalate based polyester, preferably selected from the group consisting of PET, PBT and mixtures of PET and PBT, and preferably comprises at least PET.The diacid is preferably selected from the group consisting of adipic acid, sebacic acid, and mixtures of two or more thereof, more preferably from the group consisting of adipic acid, sebacic acid and mixtures of adipic acid and sebacic acid, and preferably comprises at least adipic acid; and / or the aromatic diacid is preferably 2,5-furandicarbox-ylic acid (FDCA) and / or terephthalic acid, more preferably the aromatic diacid comprises at least terephthalic acid; and / or the mono acid is preferably lactic acid and / or the alkylene glycol is preferably selected from the group consisting of ethylene glycol, butylene glycol and mixtures of ethylene glycol and butylene glycol, and preferably is ethylene glycol, and / or the diol is preferably butane diol. "Alkylene glycol” is synonymous with an alkylene diol, i.e. is an alkylene group with terminal hydroxyl groups at both ends. In the same context, the term "diol” means an alkylene group with also terminal hydroxyl groups at both ends. Thus, for example, butylene glycol and butane diol are in fact the same chemical components, wherein the differing names were used herein in order to maintain some traceability with respect to the polymer from which the component / the monomer derives.Mixture of polyesters provided according to step (a)Preferably, the mixture of polyesters provided according to step (a) comprises the at least one biodegradable polyester and the at least one polyalkylene aromatic diacid based polyester in a weight-based ratio in the range of from 1 :9 to 9:1, more preferably in the range of from 1:4 to 4:1, more preferably in the range of from 1:2 to 2:1.01 to 05 alkanolPreferably, the C1 to C5 alkanol is selected from the group consisting of methanol, ethanol, isopropanol, and mixtures of two or more thereof, and comprises more preferably at least ethanol.241087W001- 7 -(Earth) alkali metal hydroxidePreferably, the (earth) alkali metal hydroxide is selected from the group of earth alkali metal hydroxide, alkali metal hydroxide and mixtures of earth alkali metal hydroxide and alkali metal hydroxide, preferably is at least an alkali metal hydroxide, more preferably selected from the group consisting of NaOH, KOH, and mixtures of two or more of these bases, and preferably comprises at least NaOH.Step (b)Preferably, T<bj is a temperature in the range of from 110 to <200°C, more preferably in the range of from 130 to 160°C. Preferably, the contacting in step (b) is done for a period of time of at least 5 minutes, more preferably in the range of from 5 to 300 minutes, more preferably in the range of from 15 to 180 minutes. Preferably, the contacting in step (b) of the mixture of polyesters of (a) is done with a mixture of water and at least one C1 to C5 alkanol, which comprises in the range of from 1 to 1.5, preferably in the range of from 1 to 1.1, equivalents of the at least one (earth) alkali metal hydroxide per ester unit of all polyesters of the mixture of (a). Preferably, the contacting in step (b) is done at a pressure in the range of from 10 x 103to 50 x 103hPa. Preferably, the contacting in step (b) is done under a protective gas atmosphere. Preferably, the mixture of water and at least one C1 to C5 alkanol used for the contacting in step (b) has a weight based ratio C1 to C5 alkanol : water in the range of from 70:30 to 90:10, preferably in the range of from 72:28 to 90:10, more preferably in the range of from 75:25 to 90:10, more preferably in the range of from 78:22 to 90:10, more preferably in the range of from 80:20 to 90:10.Step (c)Preferably, temperature T<C) is in the range of from 5 to 50°C, more preferably in the range of from 20 to 30°C. Preferably, step (c) is carried out at a pressure in the range of from 0.5 x 103to 1.5 x 103hPa.The further steps (d), (e), (f), (g), (h), (i) and (x) are preferably also done at a pressure in the range of from 0.5 x 103to 1.5 x 103hPa. Only distillation step (y) is done at the respective pressure required for the distillation, preferably under vacuum.Step (d)Preferably, separation of the solid phase and the liquid phase in step (d) is done by a method selected from the group consisting of filtration, centrifugation, decantation, and mixed forms of two or more of these separation methods and is more preferably done by filtration. Preferably, temperature T<dj is in the range of from 5 to 50°C, more preferably in the range of from 20 to 30°C.241087W001- 8 -Step (e)Preferably, temperature T<e) is in the range of from 20 to 100°C, more preferably in the range of from 40 to 80°C. Preferably, at least 90 weight-%, more preferably at least 95 weight-%, more preferably at least 98 weight-%, of the aqueous agent used for the contacting in step (e) are water, based on the total weight of the aqueous agent being 100 weight-%.Step (f)Preferably, the optional separating of the liquid aqueous phase obtained in (e) or in (e.2) from the solid remainder obtained in (e) or in (e.2) is done in step (f) by a physical separation method, more preferably by a physical separation method selected from the group consisting of filtration, centrifugation, decantation, and mixed forms of two or more of these separation methods and is preferably done by filtration.Step (g)Preferably, adjusting the pH value of the separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form in step (g) is done by addition of an inorganic acid and / or by an electrochemical method, wherein the inorganic acid is preferably selected from the group consisting of H2SO4, HCI, H3PO4, and mixtures of two or more of these inorganic acids, and comprises preferably at least H2SO4; and the electrochemical method is preferably selected from the group consisting of electrolysis, electrodialysis and mixed forms thereof.Step (h)Preferably, T<h) is a temperature in the range of from 70 to 90°C, more preferably in the range of from 75 to 85°C. Preferably, the physical separation method used for separating the mixture having temperature T<h) in step (h) is selected from the group consisting of filtration, centrifugation, decantation, and mixed forms of two or more of these separation methods and is more preferably filtration.Step (i)Preferably, temperature TQ is a temperature in the range of from 1 to 10°C, more preferably in the range of from 2 to241087W001-9 -Preferably, the process further comprises:(o) Preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester; preferably the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a)from the aromatic diacid, preferably terephthalic acid, obtained or obtainable from the process described herein above, preferably from step (h) described herein above; and / or from the diacid, preferably adipic acid, obtained or obtainable from the process described herein above, preferably from step (I) described herein above; and / or from the monoacid, obtained or obtainable from the process described herein above, preferably from step (z) described herein above; and / or from the alkylene glycol, preferably ethylene glycol, obtained or obtainable from the process of described herein above, preferably from step (y) described herein above; and / or from the diol, preferably butane diol, obtained or obtainable from the process described herein above, preferably from step (y) described herein above.2ndaspect- Product-by-processIn a second aspect, the present invention is directed to the one more monomer(s) obtained or obtainable from the process of the first aspect. All details, embodiments and preferred embodiments described herein above in the section related to the first aspect of the invention also apply to the second aspect of the invention.Preferably, the invention is, according to the second aspect of the invention, directed to an aromatic diacid, preferably terephthalic acid, obtained or obtainable from the process of the first aspect of the invention as described herein above, preferably from step (h) according to the process of the first aspect of the invention. Preferably, the invention is, according to the second aspect of the invention, directed to a diacid, more preferably adipic acid, obtained or obtainable from the process of the first aspect of the invention as described herein above, preferably from step (I) according to the process of the first aspect of the invention. Preferably, the invention is, according to the second aspect of the invention, directed to a monoacid, preferably lactic acid, obtained or obtainable from the process of the first aspect of the invention as described herein above, preferably from step (z) according to the process of the first aspect of the invention. Preferably, the invention is, according to the second aspect of the invention, directed to an alkylene glycol, more preferably ethylene glycol, obtained or obtainable from the process of the first aspect of the invention as described herein above, preferably from step (y) according to the process of the first aspect of the invention. Preferably, the invention is, according to the second aspect of the invention, directed to a diol, more preferably butane diol, obtained or obtainable from the process of the first aspect of the invention as described herein above, preferably from step (y) according to the process of the first aspect of the invention.3rdaspect - Use241087W001- 10-In a third aspect, the invention is directed to the use of the aromatic diacid of the second aspect of the invention as described herein above, and / or of the diacid of the second aspect of the invention as described herein above, and / or of the monoacid of the second aspect of the invention as described herein above, and / or of the alkylene glycol of the second aspect of the invention as described herein above, and / or of the diol of the second aspect of the invention as described herein above, for polymer synthesis. All details, embodiments and preferred embodiments described herein above in the section related to the first aspect of the invention and in the section related to the second aspect of the invention also apply to the third aspect of the invention.Preferably, the use is for the synthesis of at least one polyalkylene aromatic diacid based polyester, more preferably for the synthesis of at least one polyalkylene aromatic diacid based polyester selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene furan-2,5-dicarboxylate (PEF) and mixtures of two or more thereof, more preferably for the synthesis of at least one polyalkylene aromatic diacid based polyester selected from the group consisting of PET, PBT and mixtures of PET and PBT, more preferably for the synthesis of at least PET.Alternatively preferred, the use is for the synthesis of at least one biodegradable polyester, more preferably for the synthesis of at least one biodegradable polyester selected from the group consisting of polybutylene adipate terephthalate (PBAT), poly (butylene sebacate-co-terephthalate) (PBSeT), polylactid acid (PLA), and mixtures of two or more of these polyesters, more preferably for the synthesis of at least PBAT.Regarding the use, the preferred use as well as the alternatively preferred use, said use is preferably for the synthesis of the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) of the process of the first aspect of the invention as described herein above (closed loop). The "same” does not mean the identical polymer but rather the same class of polymer, i.e. if, for example, PET has been the at least one polyalkylene aromatic diacid based polyester in the mixture of polyesters provided in step (a) of said process, then the use of the one or more monomer(s) is preferably for PET synthesis.4thaspect - Method for preparing at least one polyalkylene aromatic diacid based polyesterand / or at least one biodegradable polyesterA fourth aspect of the invention is directed to a method for preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester, the method comprising(A) Providing the aromatic diacid according to the second aspect of the invention as described herein above and / or of the diacid according to the second aspect of the invention as described herein above and / or of the monoacid according to the second aspect of the invention as described herein above and / or of the alkylene241087W001- 11 -glycol according to the second aspect of the invention as described herein above and / or of the diol according to the second aspect of the invention as described herein above;(B) Preparing from the one or monomers provided according to (A) the respective at least one polyalkylene aromatic diacid based polyester and / or the at least one biodegradable polyester.All details, embodiments and preferred embodiments described herein above in the section related to the first aspect of the invention, in the section related to the second aspect of the invention, and in the section related to the third aspect of the invention also apply to the method of the fourth aspect of the invention.Preferably, the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) of the process of the first aspect of the invention as described herein above is prepared in step (B) (closed loop). The "same” does not mean the identical polymer but rather the same class of polymer, i.e. if, for example, PET has been the at least one polyalkylene aromatic diacid based polyester in the mixture of polyesters provided in step (a) of said process, then the use of the one or more monomer(s) is preferably for PET synthesis.5thaspect - ProcessIn a fifth aspect, the invention is directed to a process, preferably according to the first aspect of the invention as described herein above, comprising the step of converting the aromatic diacid according to the second aspect of the invention as described herein above and / or of the diacid according to the second aspect of the invention as described herein above and / or of the monoacid according to the second aspect of the invention as described herein above and / or of the alkylene glycol according to the second aspect of the invention as described herein above and / or of the diol according to the second aspect of the invention as described herein above and / or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to the first aspect of the invention as described herein above, to obtain a product PRF1.Preferably, the product PRF1 is selected from:i) building block or monomer; orii) polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; oriii) industrial use polymer, industrial use surfactant, descaling compound, industrial use biocide, industrial use solvent, industrial use dispersant, composition thereof or formulation thereof; oriv) agrochemical composition, agrochemical formulation auxiliary or agrochemically active ingredient; or v) active pharmaceutical ingredient or intermediate thereof, pharmaceutical excipient, animal feed additive, human food additive, dietary supplements, aroma chemical or aroma composition; or241087W001- 12 -vi) aqueous polymer dispersion, preferably polyurethane or polyurethane, poly(meth)acrylate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings polyisocyanates, hyperbranched polyethylene terephthalate polyol, polymeric dispersant for inorganic binder compositions, unsaturated polyethylene terephthalate polyol or 100% curable composition; orvii) cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or composition or formulation thereof; orviii) polymer B, polymer composition B, coating composition, other functional composition, foil, molded body, coating or coated substrate.Preferably, the content of the aromatic diacid according to the second aspect of the present invention described herein above and / or of the diacid according to the second aspect of the present invention described herein above and / or of the monoacid according to the second aspect of the present invention described herein above and / or of the alkylene glycol according to the second aspect of the present invention described herein above and / or of the diol according to the second aspect of the present invention described herein above, or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to the first aspect of the present invention described herein above, in the product PRF1 is 1 weight-% or more, preferably 2 weight-% or more, more preferably 5 weight-% or more, more preferably 15 weight-% or more, more preferably 30 weight-% or more, more preferably 40 weight-% or more, more preferably 60 weight-% or more, more preferably 80 weight-% or more, more preferably 90 weight-% or more, more preferably 95 weight-% or more; and / orPreferably, the content of the aromatic diacid of e according to the second aspect of the present invention described herein above and / or of the diacid according to the second aspect of the present invention described herein above and / or of the monoacid according to the second aspect of the present invention described herein above and / or of the alkylene glycol of according to the second aspect of the present invention described herein above and / or of the diol of according to the second aspect of the present invention described herein above, or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to the process of the first aspect of the present invention described herein above, in the product PRF1 is 100 weight-% or less, preferably 95 weight-% or less, more preferably 90 weight-% or less, more preferably 50 weight-% or less, more preferably 25 weight-% or less, more preferably 10 weight-% or less; andPreferably, the content is determined based on identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably based on mass balance, preferably the International Sustainability and Carbon Certification (ISCC) standard.The present invention is, according to a sixth aspect, also related to a product PRF1, obtained or obtainable from the process of the fifth aspect of the invention as described herein above.241087W001- 13 -The publication Prior Art Disclosure; Issue 684; paragraphs

[1000] to

[8005] ; ISSN: 2198-4786; published: February 12, 2024 will be regarded as Reference RF1, which is incorporated herein by reference in its entirety. Preferably, the product PRF1 is a product as described in Reference RF1; paragraphs

[1000] to

[8005] , Preferably, the process described herein is further a process for the production of a product, preferably product PRF1.The converting step to obtain the product PRF1 preferably comprises one or more step(s) as described below and can be performed by conventional methods well known to a person skilled in the art. The converting step preferably comprises one or more step(s) selected from:recycling, preferably depolymerizing, gasifying, pyrolyzing, and / or steam cracking; and / orpurifying, preferably crystallizing, (solvent) extracting, distilling, evaporating, hydrotreating, absorbing, adsorbing and / or subjecting to ion exchanger; and / orassembling, preferably foaming, synthesizing, chemical conversion, chemically transforming, polymerizing and / or compounding; and / orforming, preferably foaming, extruding and / or molding; and / orfinishing, preferably coating and / or smoothing.In addition, the one or more step(s) are described in detail in Reference RF1; paragraphs

[1000] to

[8005] ,The term "building block”, as used herein, comprises compounds, which are in a gaseous or liquid state under standard conditions of 0°C and 0.1 MPa. Building blocks are typically used in chemical industry to form secondary products, which provide a higher structural complexity and / or higher molecular weight than the building block on which the secondary product is based. The building block is preferably selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide, ethylene oxide, ethylene glycols, syngas comprising a mixture of hydrogen and carbon monoxide, alkanes, alkenes, alkynes and aromatic compounds. The alkanes, alkenes, alkynes and aromatic compounds comprise in particular 1 to 12 carbon atoms, respectively.The term "monomer”, as used herein, comprises molecules, which can react with each other to form polymer chains by polymerization. The monomer is preferably selected from the group consisting of (meth)acrylic acid, salts of (meth)acrylic acid; in particular sodium, potassium and zinc salts; (meth)acrolein and (meth)acrylates. (Meth)acrylates comprising 1 to 22 carbon atoms are preferred, in particular comprising 1 to 8 carbon atoms. The terms (meth)acrylic acid, (meth)acrolein or (meth)acrylate relate to acrylic acid, acrolein or acrylate and also to methacrylic acid, methacrolein or methacrylate, where applicable. Further, the monomer can be selected from hexamethylenediamine (HMD) and adipic acid.The building block can further be an intermediate compound. The term "intermediate compound”, as used herein, comprises organic reagents, which are applied for formation of compounds with higher molecular complexity. The intermediate compound can be selected for example from the group consisting of phosgene, polyisocyanates and241087W001- 14-propylene oxide. The polyisocyanates are in particular aromatic di- and polyisocyanates, preferably toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI).The building block and the monomer and typical converting step(s) to obtain the building block or monomer are described in more detail in paragraphs

[1000] to

[1012] of Reference RF1.The term "polymer A”, as used herein, comprises thermoplastic, e.g., polyamide or thermoplastic polyurethane, thermoset, e.g., polyurethane, elastomer, e.g., polybutadiene, or a copolymer or a mixture thereof and is defined in more detail in paragraphs

[2001] to

[2007] of Reference RF1.The term "polymer composition A”, as used herein, comprises all compositions comprising a polymer as described above and one or more additive(s), e.g. reinforcement, colorant, modifier and / or flame retardant, and is defined in more detail in paragraph

[2008] of Reference RF1.The term "polymer product A”, as used herein, comprises any product comprising the polymer A and / or polymer composition A as described above and is defined in more detail in paragraphs

[2009] and

[2010] of Reference RF1. The step(s) to obtain the polymer, preferably polymer A, polymer composition, preferably polymer composition A or polymer product, preferably polymer product A is / are described in more detail in paragraph

[2011] of Reference RF1.The term "industrial use polymer”, as used herein, comprises rheology, polycarboxylate, alkoxylated polyalkylenamine, alkoxylated polyalkylenimine, polyether-based, dye inhibition and soil release cleaning polymers defined in more detail in paragraphs

[3035] to

[3044] of Reference RF1. The term "industrial use surfactant”, as used herein, comprises nonionic, anionic and amphoteric industrial use surfactants defined in more detail in paragraphs

[3008] to

[3034] of Reference RF1. The term "industrial use descaling compound”, as used herein, comprises non-phosphate based builders (NPB) and phosphonates (CoP) described in more detail in paragraphs

[3001] to

[3005] of Reference RF1. The term "industrial use biocide”, as used herein, refers to a chemical compound that kills microorganisms or inhibits their growth or reproduction defined in more detail in paragraphs

[3006] to

[3007] of Reference RF1. The term "industrial use solvent”, as used herein, comprises alkyl amides, alkyl lactamides, alkyl esters, lactate esters, alkyl diester, cyclic alkyl diester, cyclic carbonates, aromatic aldehydes and aromatic esters defined in more detail in paragraphs

[3045] to

[3055] of Reference RF1. The term "industrial use dispersant”, as used herein, comprises anionic and non-ionic industrial use dispersants defined in more detail in paragraphs

[3056] to

[3058] of Reference RF1. The term "composition and / or formulation thereof” with reference to the industrial use polymers, industrial use surfactants, descaling compounds and / or industrial use biocides refers to industrial use compositions and / or institutional use products and / or fabric and home care products and / or personal care products defined in more detail in paragraph

[3059] of Reference RF1. The converting step(s) to obtain the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3060] of Reference RF1. The converting steps to obtain the industrial use composition or formulation of the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3061] of Reference RF1.241087W001- 15-The term "agrochemical composition”, as used herein, typically relates to a composition comprising an agrochemically active ingredient and at least one agrochemical formulation auxiliary. Examples of agrochemical compositions, active ingredients and auxiliaries are described in more detail in Reference RF1, paragraph

[4001] ,The agrochemical composition may take the form of any customary formulation. The agrochemical compositions are prepared in a known manner, e.g. described by Mollet and Grubemann, Formulation technology, Wiley VCH, Weinheim, 2001; or Knowles, New developments in crop protection product formulation, Agrow Reports DS243, T&F Informa, London, 2005. The converting step(s) to obtain the agrochemically active ingredients and auxiliaries may be conducted in analogy to the production step(s) of their analogues that are based on petrochemicals or other precursors that are not gained by recycling processes. In addition, conversion to compounds mentioned in sections "Polymer” and "Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or compositions or formulations thereof' may be performed as described in these sections as well as the respective paragraphs in Reference RF1.The term active pharmaceutical ingredients and / or intermediates thereof, as used herein, comprises substances that provide pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body. Intermediates thereof are isolated products that are generated during a multi-step route of synthesis of an active pharmaceutical ingredient. The term pharmaceutical excipients, as used herein, comprises compounds or compound mixtures used in compositions for various pharmaceutical applications, which are not substantially pharmaceutically active on itself. Active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients are defined in more detail in paragraph

[5001] of Reference RF1. The converting step(s) to obtain the active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms animal feed additives, human food additives, dietary supplements, as used herein, comprises Vitamins, Pro-Vitamins and active metabolites thereof including intermediates and precursors, especially Vitamin A, B, E, D, K and esters thereof, like acetate, propionate, palmitate esters or alcohols thereof like retinol or salts thereof and any combinations thereof; Tetraterpenes, especially isoprenoids like carotenoids and xanthophylls including their intermediates and precursors as well as mixtures and derivates thereof, especially beta carotene, Canthaxanthin, Citranaxanthin, Astaxanthin, Zeaxanthin, Lutein, Lycopene, Apo-carotenoids, and any combinations thereof; organic acids, especially formic acid, propionic acid and salts thereof, such as sodium, calcium or ammonium salts, and any combinations thereof, such as but not limited to mixtures of formic acid and sodium formiate, propionic acid and ammonium propionate, formic acid and propionic acid, formic acid and sodium formiate and propionic acid, propionic acid and sodium propionate and formic acid and sodium formiate; glycerides of carboxylic acids and short and medium chain fatty acids,241087W001- 16 -conjugated linoleic acids, such as omega-6 fatty acid (C18:2) methyl ester and 1 ,2-propandiol and beverage stabilizers, such as polyvinylpyrrolidone-polymer or polyvinylimidazole / polyvinylpyrrolidone-copolymer. Animal feed additives, human food additives and dietary supplements are defined in more detail in paragraph

[5002] of Reference RF1.The converting step(s) to obtain the animal feed additives, human food additives, dietary supplements may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms aroma chemical and aroma composition as used herein, comprise a volatile organic substance with a molecular weight between 70-250 g / mol comprising a functional group with a carbon skeleton of C5-C16 carbon atoms comprising linear, branched, cyclic, for example with a ring size of C5-C18, bicyclic or tricyclic aliphatic chains and but not necessarily one or more unsaturated structural elements like double bonds, triple bonds, aromatics or heteroaromatics and preferably the one or more additional functional groups are selected from alcohol, ether, ester, ketone, aldehyde, acetal, carboxylic acid, nitrile, thiol, amine. In one aspect, the aroma chemical is a terpene-based aroma chemical, for example selected from monoterpenes and monoterpenoids, sesquiterpenes and sesquiterpenoids, diterpenes, triterpenes or tetraterpenes. Aroma chemicals can be combined with further aroma chemicals to give an aroma composition. Aroma chemicals and aroma compositions are defined in more detail in paragraph

[5003] of Reference RF1.The converting step(s) to obtain the aroma chemical and aroma composition may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The term "aqueous polymer dispersion”, as used herein, comprises aqueous composition(s) comprising dispersed polymer(s) and is defined in more detail in the section

[6001] entitled "aqueous polymer dispersion” of Reference RF1. The dispersed polymer(s) may be selected from acrylic emulsion polymer(s), styrene acrylic emulsion polymer(s), styrene butadiene dispersion(s), aqueous dispersion(s) comprising composite particles, acrylate alkyd hybrid disper-sion(s), polyurethane(s) (including UV-curable polyurethanes) and polyurethane - poly(meth)acrylate hybrid poly-mer(s). The term "emulsion polymer”, as used herein, comprises polymer(s) made by free-radical emulsion polymerization. Aqueous polyurethane dispersion(s) are defined in more detail in the section

[6002] entitled "Polyurethane dispersions” of Reference RF1. UV-curable polyurethane(s) is / are defined in more detail in the section

[6017] of Reference RF1. Polyurethane - poly(meth)acrylate hybrid polymer(s) is / are defined in more detail in the section

[6016] of Reference RF1.The term "polymeric dispersant”, as used herein, comprises preferably polymer(s) comprising polyether side chain, in particular polycarboxylate ether polymer(s) and polycondensation product(s) defined in more detail in paragraph

[6020] entitled "Polymeric dispersant” of Reference RF1.The converting (polymerization) step(s) to obtain the aqueous polymer dispersion(s) comprising emulsion polymer(s) is / are defined in more detail in the section

[6003] entitled "Emulsion polymerization” of Reference RF1.241087W001- 17-The converting (polymerization) step(s) to obtain the aqueous polyurethane dispersion(s) is / are defined in more detail in the section

[6014] entitled "Process for the preparation of aqueous polyurethane dispersions” and section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them” of Reference RF1.Composition(s) and uses of aqueous polymer dispersion(s) and of polymeric dispersant(s) are defined in more detail in the following sections of Reference RF1 :section

[6004] entitled "Uses of aqueous polymer dispersions”,section

[6005] entitled "Binders for architectural and construction coatings”section

[6006] entitled "Binders for paper coating”section

[6007] entitled "Binders for fiber bonding”section

[6008] entitled "Adhesive polymers and adhesive compositions”section

[6015] entitled "Aqueous polyurethane dispersions suitable for use in coating compositions”section

[6016] entitled "Aqueous polyurethane - poly(meth)acrylate hybride polymer dispersions suitable for use in coating compositions”section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them”section

[6018] entitled "Inorganic binder compositions comprising polymeric dispersants and their use”

[6019] 100% curable coating compositionsUV-crosslinkable poly(meth)acrylate(s) and its / their uses are defined in more detail in section

[6009] entitled "UV-crossli nkable poly(meth)acrylates for use in UV-curable solvent-free hotmelt adhesives and their use for making pressure-sensitive self-adhesive articles” of Reference RF1.Polyisocyanate(s), composition(s) comprising them and their uses are defined in more detail in section

[6010] entitled "Polyisocyanates” of Reference RF1.Hyperbranched polyester polyol(s) and its / their uses are defined in more detail in section

[6011] entitled "Organic solvent based hyperbranched polyester polyols suitable for use in coating compositions” of Reference RF1. The converting step(s) to obtain the hyperbranched polyester polyols is / are defined in more detail in the section

[6012] entitled "Preparation of organic solvent based hyperbranched polyester polyols” of Reference RF1. Coating composition(s) comprising hyperbranched polyester polyol(s), polyisocyanate(s) and additive(s) and substrate(s) coated therewith are defined in more detail in section

[6013] entitled "Organic solvent based two component coating compositions comprising hyperbranched polyester polyols and polyisocyanates” of Reference RF1.241087W001- 18 -Unsaturated polyester polyol(s), solvent-based coating composition (s) comprising said unsaturated polyester polyol(s) and substrate(s) for coating with said coating composition (s) are defined in more detail in section

[6018] entitled "Organic solvent based coating composition comprising unsaturated polyester polyols” of Reference RF1.100% curable coating composition(s) is / are defined in more detail in section

[6019] of Reference RF1.Polymeric dispersant(s) for inorganic binder compositions is / are defined in more detail in section

[6020] of Reference RF1. The inorganic binder composition(s) comprising the polymeric dispersants and their use are defined in more detail in section

[6021] of Reference RF1. The converting step(s) to obtain the polymeric dispersant(s) are defined in more detail in section

[6020] of Reference RF1. The term "inorganic binder composition” comprising the polymeric disper-sant(s), as used herein, comprises preferably in particular hydraulically setting compositions and compositions comprising calcium sulfate and is defined in more detail in section

[6021] of Reference RF1 entitled "Inorganic binder compositions comprising the polymeric dispersant and their use”. Specific building material formulation(s) comprising polymeric dispersant(s) or building product(s) produced by a building material formulation comprising a polymeric dispersant are disclosed in more detail in section

[6021] of Reference RF1.The term "cosmetic surfactant”, as used herein, comprises non-ionic, anionic, cationic and amphoteric surfactants and is defined in more detail in paragraph

[7002] of Reference RF1. The term "emollient”, as used herein, refers to a chemical compound used for protecting, moisturizing, and / or lubricating the skin and is defined in more detail in paragraph

[7003] of Reference RF1. The term "wax”, as used herein, comprises pearlizers and opacifiers and is defined in more detail in paragraph

[7004] of Reference RF1. The term "cosmetic polymer”, as used herein, comprises any polymer that can be used as an ingredient in a cosmetic formulation and is defined in more detail in paragraph

[7005] of Reference RF1. The term "UV filter”, as used herein, refers to a chemical compound that blocks or absorbs ultraviolet light and is defined in more detail in paragraph

[7006] of Reference RF1. The term "further cosmetic ingredient”, as used herein, comprises any ingredient suitable for making a cosmetic formulation. Several sources disclose cosmetically acceptable ingredients. E. g. the database Cosing on the internet pages of the European Commission discloses cosmetic ingredients and the International Cosmetic Ingredient Dictionary and Handbook, edited by the Personal Care Products Council (PCPC), discloses cosmetic ingredients. The term "composition and / or formulation thereof” with reference to the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter and / or further cosmetic ingredient refers to personal care and / or cosmetic compositions or formulations defined in more detail in paragraph

[7007] of Reference RF1. The converting step(s) to obtain the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter or further cosmetic ingredient is / are defined in more detail in paragraph

[7008] of Reference RF1.The terms "polymer B”, "polymer composition B”, "coating composition”, "other functional composition”, "foil”, "molded body”, "coating” and "coated substrate” are well known to the person skilled in the art and are defined in more detail from paragraph

[8000] to

[8005] of Reference RF1.241087W001- 19 -The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The process of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The process of any one of embodiments 1, 2, 3 and 4". Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.1. A process for recycling a mixture of polyesters, wherein the mixture of polyesters comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester, the process comprising: (a) providing a mixture of polyesters which comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester;(b) contacting the mixture of polyesters of (a) with a mixture of water and at least one C1 to C5 alkanol, which comprises at least 1 equivalent of at least one (earth) alkali metal hydroxide per ester unit of all polyesters of the mixture of (a), at a temperature T<bj in the range of from >110°C to < 200 °C; thereby obtaining a dispersion;(c) reducing the temperature of the dispersion obtained in (b) from temperature T<bj to a temperature T(C>, with T(C) < T(b), thereby obtaining a solid phase and a liquid phase, wherein the solid phase comprises an (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) from the biodegradable polyester; and the liquid phase comprises water, C1 to C5 alkanol, alkylene glycol, optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester, and optionally one or more diol(s) from the biodegradable polyester.2. The process of embodiment 1 comprising:(d) separation of the solid phase and the liquid phase obtained in (c), preferably by a physical separation method, wherein separation is done at temperature T<d), wherein T<d> is preferably the same temperature as T(C), thereby obtaining a separated solid phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more alkali metal salt(s) of diacid(s) from the biodegradable polyester; and a separated liquid phase comprising water, C1 to C5 alkanol, alkylene glycol, optionally one or more diol(s) from the biodegradable polyester, and optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester.3. The process of embodiment 1 or 2 comprising:(e) contacting the separated solid phase obtained in (d) with an aqueous agent, preferably water, at a temperature T(e) > 20°C, thereby obtaining a liquid aqueous phase comprising the (earth) alkali metal salt241087W001-20-of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form and optionally a solid remainder.4. The process of embodiment 3, wherein step (e) comprises:(e.1) washing the separated solid phase obtained in (d) with a C1 to C5 alkanol, preferably at a temperature T(e.i) with T(e.i) = T(d) = T(C>; thereby obtaining a washed separated solid phase;(e.2) contacting the washed separated solid phase obtained in (e.1) with anaqueous agent, preferably water, at a temperature T(e> > 20°C, thereby obtaining a liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form and optionally a solid remainder.5. The process of any one of embodiments 1 to 4 comprising(f) optionally separating the liquid aqueous phase obtained in (e) or in (e.2) from the solid remainder obtained in (e) or in (e.2), preferably by a physical separation method; thereby obtaining a separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form.6. The process of any one of embodiments 1 to 5 comprising:(g) Adjusting the pH value of the separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form obtained in (e), (e.2) or (f), preferably by addition of an inorganic acid and / or by an electrochemical method, to a pH value < 7, preferably a pH value in the range of from 3 to 6.9, more preferably in the range of from 5.5 to 6.5, thereby obtaining an aqueous mixture, the aqueous mixture comprising a precipitate comprising aromatic diacid and optionally at least parts of one or more diacid(s) and a liquid aqueous part.7. The process of any one of embodiments 1 to 6 comprising:(h) separating the precipitate formed in step (g) from the liquid aqueous part mixture at a temperature T<hj >70°C by a physical separation method, optionally including one or more washing steps at T<h), thereby obtaining a separated liquid aqueous phase, which comprises the one or more diacid(s), and a separated solid remainder, which comprises the aromatic diacid.8. The process of any one of embodiments 1 to 7 comprising:(I) Adjusting the temperature of the aqueous liquid phase, which comprises the one or more diacid(s), obtained in (h), to a temperature T(i) < 10°C, thereby obtaining the one or more diacid(s) in solid form (crystallization).241087W001-21 -9. The process of any one of embodiments 1 to 8 comprising:(x) Adjusting the pH value of the separated liquid phase comprising water, C1 to C5 alkanol, alkylene glycol, optionally one or more diol(s) from the biodegradable polyester, and optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester obtained in (d) to a pH value < 7, and adding an earth alkali metal salt, preferably CaCOa, thereby optionally obtaining a solid residue comprising one or more earth alkali metal salt(s), preferably calcium salt(s), of monoacid(s) from the biodegradable polyester and a liquid phase comprising water, C1 to C5 alkanol, alkylene glycol and optionally one or more diol(s) from the biodegradable polyester;(y) separation of the liquid phase obtained in (x) by distillation and / or liquid / liquid extraction, thereby obtaining a fraction comprising alkylene glycol, a fraction comprising C1 to C5 alkanol and optionally a fraction comprising one or more diol(s) from the biodegradable polyester.10. The process of embodiment 9, comprising(z) contacting the solid residue comprising one or more earth alkali metal salt(s), preferably calcium salt(s), of monoacid(s) from the biodegradable polyester, obtained from step (x) with an inorganic acid, preferably selected from the group consisting of_H2SO4, HCI, H3PO4, and mixtures of two or more of these inorganic acids, thereby obtaining the monoacid(s).11. The process of any one of embodiments 1 to 10, wherein the at least one biodegradable polyester is selected from the group consisting of polybutylene adipate terephthalate (PBAT), poly (butylene sebacate-co-tereph- thalate) (PBSeT), polylactid acid (PLA), and mixtures of two or more of these polyesters, and preferably comprises at least PBAT.12. The process of any one of embodiments 1 to 11, wherein the at least one polyalkylene aromatic diacid based polyester is selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene f uran-2, 5-d icarboxy I ate (PEF) and mixtures of two or more thereof, preferably the at least one polyalkylene aromatic diacid based polyester is at least one polyalkylene terephthalate based polyester, preferably selected from the group consisting of PET, PBT and mixtures of PET and PBT, and preferably comprises at least PET.13. The process of any one of embodiments 1 to 12, wherein the mixture of polyesters provided according to step (a) comprises the at least one biodegradable polyester and the at least one polyalkylene aromatic diacid based polyester in a weight based ratio in the range of from 1:9 to 9:1, preferably in the range of from 1:4 to 4:1, more preferably in the range of from 1:2 to 2:1.241087W001-22 -14. The process of any one of embodiments 1 to 13, wherein the C1 to C5 alkanol is selected from the group consisting of methanol, ethanol, isopropanol, and mixtures of two or more thereof, and comprises preferably at least ethanol.15. The process of any one of embodiments 1 to 14, wherein the (earth) alkali metal hydroxide is selected from the group of earth alkali metal hydroxide, alkali metal hydroxide and mixtures of earth alkali metal hydroxide and alkali metal hydroxide, preferably is at least an alkali metal hydroxide, more preferably selected from the group consisting of NaOH, KOH, and mixtures of two or more of these bases, and preferably comprises at least NaOH.16. The process of any one of embodiments 1 to 15, wherein T<bj is a temperature in the range of from 110 to <200°C, preferably in the range of from 130 to 160°C.17. The process of any one of embodiments 1 to 16, wherein the contacting in step (b) is done for a period of time of at least 5 minutes, preferably in the range of from 5 to 300 minutes, more preferably in the range of from 15 to 180 minutes.18. The process of any one of embodiments 1 to 17, wherein the contacting in step (b) of the mixture of polyesters of (a) is done with a mixture of water and at least one C1 to C5 alkanol, which comprises in the range of from 1 to 1.5, preferably in the range of from 1 to 1.1 , equivalents of the at least one (earth) alkali metal hydroxide per ester unit of all polyesters of the mixture of (a).19. The process of any one of embodiments 1 to 18, wherein the contacting in step (b) is done at a pressure in the range of from 10 x 103to 50 x 103hPa.20. The process of any one of embodiments 1 to 19, wherein the contacting in step (b) is done under a protective gas atmosphere.21. The process of any one of embodiments 1 to 20, wherein the mixture of water and at least one C1 to C5 alkanol used for the contacting in step (b) has a weight based ratio C1 to C5 alkanol : water in the range of from 70:30 to 90:10, preferably in the range of from 72:28 to 90:10, more preferably in the range of from 75:25 to 90:10, more preferably in the range of from 78:22 to 90:10, more preferably in the range of from 80:20 to 90:10.22. The process of any one of embodiments 1 to 21, wherein temperature T<C) is in the range of from 5 to 50°C, preferably in the range of from 20 to 30°C.241087W001-23 -23. The process of any one of embodiments 1 to 22, wherein step (c) is carried out at a pressure in the range of from 0.5 x 103to 1.5 x 103hPa.24. The process of any one of embodiments 2 to 23, wherein separation of the solid phase and the liquid phase in step (d) is done by a method selected from the group consisting of filtration, centrifugation, decantation, and mixed forms of two or more of these separation methods and is preferably done by filtration.25. The process of any one of embodiments 2 to 24, wherein temperature T<dj is in the range of from 5 to 50°C, preferably in the range of from 20 to 30°C.26. The process of any one of embodiments 3 to 25, wherein temperature T(e> is in the range of from 20 to 100°C, preferably in the range of from 40 to 80°C.27. The process of any one of embodiments 3 to 26, wherein at least 90 weight-%, preferably at least 95 weight- %, more preferably at least 98 weight-%, of the aqueous agent used for the contacting in step (e) are water, based on the total weight of the aqueous agent being 100 weight-%.28. The process of any one of embodiments 5 to 27, wherein optionally separating the liquid aqueous phase obtained in (e) or in (e.2) from the solid remainder obtained in (e) or in (e.2) is done in step (f) by a physical separation method, preferably by a physical separation method selected from the group consisting of filtration, centrifugation, decantation, and mixed forms of two or more of these separation methods and is preferably done by filtration.29. The process of any one of embodiments 6 to 28, wherein adjusting the pH value of the separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form in step (g) is done by addition of an inorganic acid and / or by an electrochemical method, wherein the inorganic acid is preferably selected from the group consisting of H2SO4, HCI, H3PO4, and mixtures of two or more of these inorganic acids, and comprises preferably at least H2SO4; and the electrochemical method is preferably selected from the group consisting of electrolysis, electrodialysis and mixed forms thereof.30. The process of any one of embodiments 7 to 29, wherein T<hj is a temperature in the range of from 70 to 90°C, preferably in the range of from 75 to 85°C.241087W001-24-31. The process of any one of embodiments 7 to 30, wherein the physical separation method used for separating the mixture having temperature T<h> in step (h) is selected from the group consisting of filtration, centrifugation, decantation, and mixed forms of two or more of these separation methods and is preferably filtration.32. The process of any one of embodiments 8 to 31, wherein temperature TQ is a temperature in the range of from 1 to 10°C, preferably in the range of from 2 to 6°C.33. Aromatic diacid, preferably terephthalic acid, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (h) according to embodiment 7.34. Diacid, preferably adipic acid, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (I) according to embodiment 8.35. Monoacid, preferably lactic acid, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (z) according to embodiment 10.36. Alkylene glycol, preferably ethylene glycol, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (y) according to embodiment 9.37. Diol, preferably butane diol, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (y) according to embodiment 9.38. Use of the aromatic diacid of embodiment 33 and / or of the diacid of embodiment 34 and / or of the monoacid of embodiment 35 and / or of the alkylene glycol of embodiment 36 and / or of the diol of embodiment 37 for polymer synthesis.39. The use of embodiment 38 for the synthesis of at least one polyalkylene aromatic diacid based polyester, preferably for the synthesis of at least one polyalkylene aromatic diacid based polyester selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene furan- 2,5-dicarboxy late (PEF) and mixtures of two or more thereof, more preferably for the synthesis of at least one polyalkylene aromatic diacid based polyester selected from the group consisting of PET, PBT and mixtures of PET and PBT, more preferably for the synthesis of at least PET.241087W001-25-40. The use of embodiment 38 for the synthesis of at least one biodegradable polyester, preferably for the synthesis of at least one biodegradable polyester selected from the group consisting of polybutylene adipate terephthalate (PBAT), poly(butylene sebacate-co-terephthalate) (PBSeT), polylactid acid (PLA), and mixtures of two or more of these polyesters, more preferably for the synthesis of at least PBAT.41. The use of any one of embodiments 38 to 40 for the synthesis of the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) of the process of embodiment 1 (closed loop).42. A process for preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester, the method comprising(A) Providing the aromatic diacid of embodiment 33 and / or of the diacid of embodiment 34 and / or of the monoacid of embodiment 35 and / or of the alkylene glycol of embodiment 36 and / or of the diol of embodiment 37;(B) Preparing from the one or monomers provided according to (A) the respective at least one polyalkylene aromatic diacid based polyester and / or the at least one biodegradable polyester.43. The process of embodiment 42, wherein the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) of the process of embodiment 1 is prepared in step (B) (closed loop).44. The process of any one of embodiments 1 to 43, further comprising:(o) Preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester; preferably the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) from the diacid, preferably adipic acid, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (I) according to embodiment 8; and / or from the monoacid, preferably lactic acid, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (z) according to embodiment 10; and / or from the alkylene glycol, preferably ethylene glycol, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (y) according to embodiment 9; and / or from the diol, preferably butane diol, obtained or obtainable from the process of any one of embodiments 1 to 32, preferably from step (y) according to embodiment 9.45. Process, preferably according to any one of embodiments 1 to 32 comprising the step of converting the aro- matic diacid of embodiment 33 and / or of the diacid of embodiment 34 and / or of the monoacid of embodiment241087W001-26 -35 and / or of the alkylene glycol of embodiment 36 and / or of the diol of embodiment 37 and / or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to any one of any one of embodiments 1 to 32, to obtain a product PRF1.46. Process according to embodiment 45,wherein the product PRF1 is selected from:i) building block or monomer; orii) polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; oriii) industrial use polymer, industrial use surfactant, descaling compound, industrial use biocide, industrial use solvent, industrial use dispersant, composition thereof or formulation thereof; oriv) agrochemical composition, agrochemical formulation auxiliary or agrochemically active ingredient; or v) active pharmaceutical ingredient or intermediate thereof, pharmaceutical excipient, animal feed additive, human food additive, dietary supplements, aroma chemical or aroma composition; or vi) aqueous polymer dispersion, preferably polyurethane or polyurethane, poly(meth)acrylate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings polyisocyanates, hyperbranched polyethylene terephthalate polyol, polymeric dispersant for inorganic binder compositions, unsaturated polyethylene terephthalate polyol or 100% curable composition; orvii) cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or composition or formulation thereof; orviii) polymer B, polymer composition B, coating composition, other functional composition, foil, molded body, coating or coated substrate.47. Process according to embodiment 45 or 46,wherein the content of the aromatic diacid of embodiment 33 and / or of the diacid of embodiment 34 and / or of the monoacid of embodiment 35 and / or of the alkylene glycol of embodiment 36 and / or of the diol of embodiment 37, or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to any one of any one of embodiments 1 to 32, in the product PRF1 is 1 weight-% or more, preferably 2 weight-% or more, more preferably 5 weight-% or more, more preferably 15 weight-% or more, more preferably 30 weight-% or more, more preferably 40 weight-% or more, more preferably 60 weight-% or more, more preferably 80 weight-% or more, more preferably 90 weight-% or more, more preferably 95 weight-% or more; and / orwherein the content of the aromatic diacid of embodiment 33 and / or of the diacid of embodiment 34 and / or of the monoacid of embodiment 35 and / or of the alkylene glycol of embodiment 36 and / or of the diol of embodi-241087W001-27 -ment 37, or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to any one of any one of embodiments 1 to 32, in the product PRF1 is 100 weight-% or less, preferably 95 weight-% or less, more preferably 90 weight-% or less, more preferably 50 weight-% or less, more preferably 25 weight-% or less, more preferably 10 weight-% or less; andpreferably wherein the content is determined based on identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably based on mass balance, preferably the International Sustainability and Carbon Certification (ISCC) standard.48. A product PRF1, obtained or obtainable from the process of embodiment 47.The present invention is further illustrated by the following reference examples, comparative examples, and examples.ExamplesReference Example 1 : General procedure for depolymerization of mixed polyestersA mixture comprising at least PBAT and at least one additional polyalkylene aromatic diacid based polyester was exposed to alkaline conditions (preferably in the range of from 1.0-1.5 equivalents of inorganic base, preferably an alkali metal cation hydroxide (e.g. NaOH, KOH) per ester unit, more preferably in the range of from 1.0-1.1 equivalents per ester unit) in a mixture of water and a short-chain aliphatic alcohol (eg. methanol, ethanol) at a temperature >110°C (preferably in the range of from 110 to 220°C, more preferably in the range of from 130 to 160°C) for a defined period of time depending on the reaction temperature (preferably in the range of from 5 to 300 min, more preferably in the range of from 15 to 180 min). The reaction was carried out in a closed or closable, pressure resistant, vessel equipped with a stirring device in a protective atmosphere under pressure.After completion of the reaction, the reaction mixture was cooled to lower temperature (preferably in the range of from 5 to 50°C, more preferably in the range of from 20 to 30°C, more preferably about 25°C) and a filtration step at said lower temperature was implemented in order to separate the insoluble fraction containing the precipitated alkali metal cation adipate and alkali metal cation terephthalate and the liquid fraction containing ethanol, water as well as diols from the polyesters such as 1,4-butane diol and alkylene glycol. The solid fraction was washed with short-chain aliphatic alcohol and dissolved in warm water (temperature of the water preferably in the range of from 20 to 100°C, more preferably in the range of from 40 to 80°C), thereby dissolving the precipitated sodium salts while other nonconverted fractions containing unreacted polyolefins or inorganic filler materials such as glass fibers were removed from the product stream. The pH value of the aqueous filtrate was then adjusted to a pH < 7 (e.g. by addition of an acid or by electrochemical methods) and the formed organic acids were recovered by filtration at high temperature,241087W001-28 -preferably in the range of from 70 to 90°C (terephthalic acid) and crystallization at low temperature, preferably in the range of from 1 to 10°C, followed by filtration at a temperature in the range of from 20 to 25°C (adipic acid).Additionally, the liquid product stream from the filtration at lower temperature (after the initial hydrolysis reaction and the cooling) was furthermore pH adjusted to a pH of <7, and filtrated, wherein the resulting liquid fraction was processed by state-of-the-art technology such as fine distillation.Example 1 : Depolymerization of a mixture of PBAT and PETA mixture of 10 g PBAT (containing 25 mol% adipic acid, 25 mol% terephthalic acid and 50 mol% 1 ,4-butanediol) and 10 g PET (containing 50 mol% terephthalic acid and 50 mol% ethylene glycol) was treated according to the general procedure of Reference Example 1 in that these compounds were together with 170 g ethanol, 30 g water and 8.1 g NaOH filled into an autoclave equipped with a mechanical stirrer. The reaction vessel was inertized with 30 bar nitrogen and kept under pressure. The stirrer was set to 60 revolutions per minute (rpm) and the reaction temperature was increased to 180°C. After the temperature of 180°C was reached, the reaction was stirred at 180°C for 3 h and then immediately cooled to ambient temperature (in the range of from 20 to 30°C). The reaction mixture was filtered at ambient temperature and the filter cake was washed with ethanol (2x10 ml). The obtained solid fraction was redissolved in water and the pH value was adjusted with H2SO4 to pH 6, leading to precipitation of a white solid. The solid was removed from the suspension by hot filtration at 80°C, dried in vacuo and identified by1H NMR as terephthalic acid (10.5 g, 92 % yield based on the sum of terephthalate present in the initial PBAT and PET). The filtrate from the hot filtration at 80°C was reconcentrated in vacuo and recrystallized at 4 °C over night to yield white crystals, which were separated by filtration at a temperature in the range of from 20 to 25°C, dried in vacuo and identified by1H NMR as adipic acid (2.7 g, 89% yield based on the adipate present in the initial PBAT).The liquid fraction from the filtration at ambient temperature (after the initial hydrolysis reaction and the cooling) was furthermore pH adjusted to a pH of <7 and filtrated, wherein the resulting liquid fraction was purified by fractional fine distillation to obtain two product fractions, which were identified by1H NMR as ethylene glycol (2.4 g, 80% yield based on the polyethylene present in the initial PET) and 1 ,4-butanediol (3.6 g, 95% yield based on the butylene present in the initial PBAT).Cited LiteratureChengfeng Shen, Xue Zhao, Yuwei Long, Wenli An, Xuelian Zhou, Xuehui Liu, Shimei Xu, and Yu-Zhong Wang, ACS Sustainable Chem. Eng. 2023, 11, 2005-2013DesVeaux et al., 2024, One Earth 7, 2204-2222; https: / / doi.Org / 10.1016 / j.oneear.2024.11.007B. Raheem et al., Journal of Cleaner Production, 225 (2019), 1052-1064

Claims

241087W001- 29 -Claims1. A process for recycling a mixture of polyesters, wherein the mixture of polyesters comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester, the process comprising: (a) providing a mixture of polyesters which comprises at least one biodegradable polyester and at least one polyalkylene aromatic diacid based polyester;(b) contacting the mixture of polyesters of (a) with a mixture of water and at least one C1 to C5 alkanol, which comprises at least 1 equivalent of at least one (earth) alkali metal hydroxide per ester unit of all polyesters of the mixture of (a), at a temperature T<bj in the range of from >110°C to < 200 °C; thereby obtaining a dispersion;(c) reducing the temperature of the dispersion obtained in (b) from temperature T<bj to a temperature T<C), with T(C) < T(b), thereby obtaining a solid phase and a liquid phase, wherein the solid phase comprises an (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) from the biodegradable polyester; and the liquid phase comprises water, C1 to C5 alkanol, alkylene glycol, optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester, and optionally one or more diol(s) from the biodegradable polyester.

2. The process of claim 1 comprising:(d) separation of the solid phase and the liquid phase obtained in (c), preferably by a physical separation method, wherein separation is done at temperature T<d), wherein T<d) is preferably the same temperature as T(C), thereby obtaining a separated solid phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more alkali metal salt(s) of diacid(s) from the biodegradable polyester; and a separated liquid phase comprising water, C1 to C5 alkanol, alkylene glycol, optionally one or more diol(s) from the biodegradable polyester, and optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester.

3. The process of claim 1 or 2 comprising:(e) contacting the separated solid phase obtained in (d) with an aqueous agent, preferably water, at a temperature T(e) > 20°C, thereby obtaining a liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form and optionally a solid remainder.

4. The process of claim 3, wherein step (e) comprises:(e.1) washing the separated solid phase obtained in (d) with a C1 to C5 alkanol, preferably at a temperature T(e.i) with T(e.i) = T(d) = T(C>; thereby obtaining a washed separated solid phase;(e.2) contacting the washed separated solid phase obtained in (e.1) with an241087W001- 30-aqueous agent, preferably water, at a temperature T<e) > 20°C, thereby obtaining a liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form and optionally a solid remainder.

5. The process of any one of claims 1 to 4 comprising(f) optionally separating the liquid aqueous phase obtained in (e) or in (e.2) from the solid remainder obtained in (e) or in (e.2), preferably by a physical separation method; thereby obtaining a separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form.

6. The process of any one of claims 1 to 5 comprising:(g) adjusting the pH value of the separated liquid aqueous phase comprising the (earth) alkali metal salt of aromatic diacid and optionally one or more (earth) alkali metal salt(s) of diacid(s) in dissolved form obtained in (e), (e.2) or (f), preferably by addition of an inorganic acid and / or by an electrochemical method, to a pH value < 7, preferably a pH value in the range of from 3 to 6.9, more preferably in the range of from 5.5 to 6.5, thereby obtaining an aqueous mixture, the aqueous mixture comprising a precipitate comprising the aromatic diacid and optionally at least parts of one or more diacid(s) and a liquid aqueous part.

7. The process of any one of claims 1 to 6 comprising:(h) separating the precipitate formed in step (g) from the liquid aqueous part mixture at a temperature T<hj >70°C by a physical separation method, optionally including one or more washing steps at T<h), thereby obtaining a separated liquid aqueous phase, which comprises the one or more diacid(s), and a separated solid remainder, which comprises the aromatic diacid.

8. The process of any one of claims 1 to 7 comprising:(i) adjusting the temperature of the aqueous liquid phase, which comprises the one or more diacid(s), obtained in (h), to a temperature T(i) < 10°C, thereby obtaining the one or more diacid(s) in solid form (crystallization).

9. The process of any one of claims 1 to 8 comprising:(x) adjusting the pH value of the separated liquid phase comprising water, C1 to C5 alkanol, alkylene glycol, optionally one or more diol(s) from the biodegradable polyester, and optionally one or more (earth) alkali metal salt(s) of monoacid(s) from the biodegradable polyester obtained in (d) to a pH value < 7, and adding an earth alkali metal salt, preferably CaCOa, thereby optionally obtaining a solid residue comprising one or more earth alkali metal salt(s), preferably calcium salt(s), of monoacid(s) from the241087W001- 31 -biodegradable polyester and a liquid phase comprising water, C1 to C5 alkanol, alkylene glycol and optionally one or more diol(s) from the biodegradable polyester;(y) separation of the liquid phase obtained in (x) by distillation and / or liquid / liquid extraction, thereby obtaining a fraction comprising alkylene glycol, a fraction comprising C1 to C5 alkanol and optionally a fraction comprising one or more diol(s) from the biodegradable polyester.

10. The process of claim 9, comprising(z) contacting the solid residue comprising one or more earth alkali metal salt(s), preferably calcium salt(s), of monoacid(s) from the biodegradable polyester, obtained from step (x) with an inorganic acid, preferably selected from the group consisting of H2SO4, HCI, H3PO4, and mixtures of two or more of these inorganic acids, thereby obtaining the monoacid(s).

11. The process of any one of claims 1 to 10, wherein the at least one biodegradable polyester is selected from the group consisting of polybutylene adipate terephthalate (PBAT), poly(butylene sebacate-co-terephthalate) (PBSeT), polylactid acid (PLA), and mixtures of two or more of these polyesters, and preferably comprises at least PBAT; and / or, preferably and, wherein the at least one polyalkylene aromatic diacid based polyester is selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene furan-2,5-dicarboxy late (PEF) and mixtures of two or more thereof, preferably the at least one polyalkylene aromatic diacid based polyester is at least one polyalkylene terephthalate based polyester, preferably selected from the group consisting of PET, PBT and mixtures of PET and PBT, and preferably comprises at least PET.

12. Aromatic diacid, preferably terephthalic acid, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (h) according to claim 7; and / or diacid, preferably adipic acid, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (i) according to claim 8; and / or monoacid, obtained or obtainable from the process of any one of claims 1 to 11 , preferably from step (z) according to claim 10; and / or alkylene glycol, preferably ethylene glycol, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (y) according to claim 9; and / or diol, preferably butane diol, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (y) according to claim 9.

13. Use of the aromatic diacid of claim 12 and / or of the diacid of claim 12 and / or of the monoacid of claim 12 and / or of the alkylene glycol of claim 12 and / or of the diol of claim 12 for polymer synthesis; preferably for the synthesis of at least one polyalkylene aromatic diacid based polyester;or preferably for the synthesis of at least one biodegradable polyester;241087W001- 32 -more preferably for the synthesis of the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) of the process of claim 1.

14. A method for preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester, the method comprising(A) Providing aromatic diacid of claim 12 and / or of the diacid of claim 12 and / or of the monoacid of claim 12 and / or of the alkylene glycol of claim 12 and / or of the diol of claim 12;(B) Preparing from the one or monomers provided according to (A) the respective at least one polyalkylene aromatic diacid based polyester and / or the at least one biodegradable polyester , wherein preferably the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a) of the process of claim 1 is prepared in step (B).

15. The process of any one of claims 1 to 11, further comprising:(o) Preparing at least one polyalkylene aromatic diacid based polyester and / or at least one biodegradable polyester; preferably the same at least one polyalkylene aromatic diacid based polyester and / or the same at least one biodegradable polyester as present in the mixture of polyesters provided in step (a), from the aromatic diacid, preferably terephthalic acid, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (h) according to claim 7; and / or from the diacid, preferably adipic acid, obtained or obtainable from the process of any one of claims 1 to 11 , preferably from step (i) according to claim 8; and / or from the monoacid, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (z) according to claim 10; and / or from the alkylene glycol, preferably ethylene glycol, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (y) according to claim 9; and / or from the diol, preferably butane diol, obtained or obtainable from the process of any one of claims 1 to 11, preferably from step (y) according to claim 9.

16. Process, preferably according to any one of claims 1 to 11 comprising the step of converting the aromatic diacid of claim 12 and / or of the diacid of claim 12 and / or of the monoacid of claim 12 and / or of the alkylene glycol of claim 12 and / or of the diol of claim 12 and / or a solid remainder comprising at least one polyolefin obtainable by or obtained by the process according to any one of any one of claims 1 to 11, to obtain a product PRF1.