Method for processing a raw product fraction from a recycling process of a polyurethane product

Abstract

The present invention relates to a method for processing a (raw product) fraction containing a polyether polyol and an amine, wherein the (raw product) fraction originates from a recycling process of a polyurethane product based on an isocyanate component and a polyol component comprising the polyether polyol, the method comprising a step (α): treating the (raw product) fraction with carbon dioxide, and separating it into an organic polyether polyol fraction and an aqueous amine fraction.

Description

[0001] 2024PF30058 - Abroad

[0002] - 1 -

[0003] METHOD FOR REPROCESSING A RAW PRODUCT FRACTION FROM A RECYCLING PROCESS OF A POLYURETHANE PRODUCT

[0004] The project that led to this application has received funding under grant agreement no. 101036854 from the European Union’s Horizon 2020 research and innovation programme.

[0005] The present invention relates to a process for the reprocessing of (at least) one (crude product) fraction containing (at least) one polyether polyol and (at least) one amine, wherein the (at least one) (crude product) fraction originates from a recycling process of a polyurethane product based on an isocyanate component and a polyol component comprising the (at least one) polyether polyol, the process comprising a step (a):

[0006] Treatment, particularly in the context of an extraction, of the (at least one) (crude product) fraction with carbon dioxide and a separation into an organic polyether polyol fraction and an aqueous amine fraction.

[0007] Polyurethane products have a wide range of applications in industry and everyday life. A common distinction is made between polyurethane foams and so-called "CASE" products, where "CASE" is a collective term for polyurethane coatings (e.g., paints), adhesives, sealants, and elastomers. Polyurethane foams are typically divided into rigid foams (which can be used, for example, as insulating materials, such as in refrigerators or in building construction) and flexible foams (which can be used, for example, as cushioning materials, such as in upholstered furniture or car seats).Despite their differences, all these products share the basic polyurethane structure, which is formed by the polyaddition reaction of a multivalent isocyanate (hereinafter referred to as isocyanate) and a polyol, and is suitable, for example, for a polyurethane (PU) based on a diisocyanate O=C=NRN=C=O and a diol HO-R'-OH (where R and R' denote organic residues).

[0008] - [O-R'-O-(O=C)-HN-R-NH-(C=O)] - can be represented.

[0009] Precisely because of the great economic success of polyurethane products, large quantities of polyurethane waste (e.g., from old mattresses or seating furniture) are also generated, which must be put to good use. The technical details are as follows: 2024PF30058 - Abroad

[0010] - 2 - The simplest and easiest way to reuse polyurethane is incineration, utilizing the heat released for other processes, such as industrial manufacturing. However, this method does not allow for closing the raw material cycles. Another type of reuse is so-called "physical recycling," in which polyurethane waste is mechanically shredded and used in the production of new products. This type of recycling naturally has its limitations, which is why there has been no shortage of attempts to recover the raw materials underlying polyurethane production through chemical breakdown of the polyurethane bonds (chemolysis) (so-called "chemical recycling").The valuable materials recovered through such chemical decomposition include (1) the polyols underlying the polyurethane products (in the example above, HO-R'-OH) or, depending on the type of polyol originally used, monomeric and / or oligomeric derivatives thereof, and (2) the amines corresponding to the isocyanates originally used (in the example above, H₂N-R-NH₂), which can be phosgenated back into isocyanates (in the example above, O=C=NRN=C=O) after processing. In certain variants of chemical recycling, the isocyanates can also be obtained directly (by thermal decomposition of initially formed low-molecular-weight carbamates).

[0011] A summary of the polyurethane recycling processes known up to 2018 is provided by the review article by Simon, Borreguero, Lucas and Rodriguez in Waste Management 2018, 76, 147 - 171 [1], where glycolysis (see below No. 2) is highlighted as being particularly important.

[0012] Various approaches to chemical recycling have been developed in the past. Five of them are briefly summarized below:

[0013] 1. Hydrolysis of urethanes by reaction with water to obtain amines and polyols with the formation of carbon dioxide.

[0014] 2. Glycolysis (alcohollysis) of urethanes by reaction with alcohols, whereby the polyols incorporated into the urethane groups are replaced by the alcohol used and thus released. This process is usually referred to in the literature as transesterification (more precisely: transurethanization). This type of chemical recycling is commonly referred to as glycolysis in the literature, regardless of the specific type of alcohol used, although this term is actually only applicable to glycols, and one should therefore more generally speak of alcoholysis. Hydrolysis can follow glycolysis. If the hydrolysis is carried out in the presence of the unchanged glycolysis mixture (i.e., without prior separation of the polyols formed), it is referred to as 2024PF30058 - Abroad

[0015] - 3 -

[0016] 3. Hydroglycolysis (hydroalcohollysis) of urethane bonds. It is also possible, of course, to add alcohol and water from the beginning, in which case the hydrolysis and glycolysis processes described above occur in parallel.

[0017] 4. Aminolysis of urethane bonds by reaction with primary or secondary amines, whereby the polyols incorporated into the urethane groups are replaced by the amine used and thus released. In this case, the urethane groups are converted to urea groups. Similarly, the R-NH (C=O) bonds in the urethanes can also be cleaved, and the R-NH groups replaced by the amine used in the aminolysis, releasing the amine R-NH₂ corresponding to the originally used isocyanate. If amino acids with primary or secondary amino groups are used, the alcohol groups of the amino alcohol used can also react with urethane bonds, potentially leading to the formation of carbamates. According to most of the prior art, aminolysis can be followed by hydrolysis in a separate step.

[0018] 5. A reaction procedure corresponding to hydroglycolysis, in which amines or amino alcohols and water are used as reagents without prior separation of the released polyols, is described in WO 2023 / 083968 Al and is referred to there as aminohydrolysis.

[0019] Chemical recycling is particularly attractive for polyurethane products based on polyether polyols, as these polyols, due to their comparatively high stability, can be recovered essentially as such, i.e., chemically unchanged. This is not possible for polyurethane products based on polyols with comparatively reactive functional groups in the polymer chain (such as polyester polyols), since chemolysis inevitably leads to the cleavage of these functional groups. However, the crude recovered polyether polyols regularly still contain significant amounts of amine and / or its carbamate or urea precursor compounds. Similarly, the crude recovered amines regularly still contain significant amounts of polyether polyols.Purifying these crude process products (crude product fractions) to such an extent that the proportion of the other target product is reduced to negligible levels is not trivial and has been the subject of numerous studies. Depending on the nature of the recovered valuable materials, they cannot always be distilled without decomposition (e.g., long-chain polyether polyols or 2024PF30058 - foreign).

[0020] - 4 -

[0021] Polymethylenepolyphenylenepolyamines (pMDA) are derived from the corresponding polymethylenepolyphenylenepolycyanates (pMDI), making isolation in high purity very difficult. Regardless of the boiling point, the purification of certain amines is complicated simply by their low water solubility. Typically, the separation of polyols and amines is achieved by converting the polyols into a relatively nonpolar organic phase and the amines into a relatively polar aqueous phase, followed by separation of the two phases. If the amine is only moderately or poorly water-soluble, the prior art usually involves extraction with an aqueous acid (especially hydrochloric acid), which causes the amine to pass into the aqueous phase in a protonated form. This must then, of course, be neutralized by a base treatment.The process therefore requires the stoichiometric use of an acid and a base, which is associated with high costs and increased effort in wastewater treatment.

[0022] WO 2020 / 260387 Al and WO 2022 / 063764 Al describe extraction processes for the work-up of product mixtures from the alcoholysis of a polyurethane product. A carbamate and a polyol phase are obtained, and the carbamate phase is subjected to separate hydrolysis to recover the underlying amines.

[0023] WO 2023 / 099420 describes a process for obtaining high-purity polyols from polyurethane products whose underlying isocyanate component comprises only those isocyanates whose corresponding amines have a boiling point (at 1013 mbapabs.) of no more than 410 °C. In this process, the polyurethane products are cleaved by hydroalcohollysis, and the resulting product mixture is processed by a combination of extraction steps and distillation and / or stripping to obtain high-quality polyols. The amines formed in the hydroalcohollysis can also be recovered.

[0024] As already mentioned, WO 2023 / 083968 Al deals with amino hydrolysis. For the complete separation of amine residues from recycled polyether polyols, the use of efficient distillation apparatus is recommended.

[0025] None of the aforementioned applications describe the use of carbon dioxide (CO2) to improve the efficiency of separating recycled polyether polyols and recycled amines. The use of CO2 in other contexts is described, for example, in the following literature references:

[0026] WO 2010 / 125743 Al describes the decomposition of pMDI-based ureas by hydrolysis in supercritical CO2. 2024PF30058 - Foreign

[0027] - 5 -

[0028] Karen L. Toews, Robert M. Shroll, Chien M. Wai, and Neil G. Smart describe in Anal. Chem. 1995, 67 (22), 4040-4043 a study concerning the direct measurement of the pH of water in contact with supercritical CO2 by analyzing the spectra of a pH indicator with a UV-VIS spectrophotometer. The pH was analyzed under pressures of 70 to 200 atm and at temperatures of 25 to 70 °C. The measured pH ranged from 2.80 to 2.95 with a relative standard deviation of < 1.5%. The effects of pH on the efficiency of supercritical fluid extraction of metals and ionizable organic compounds in aqueous systems are discussed.

[0029] Kevin N. West, Christy Wheeler, Jonathan P. McCamey, Kris N. Griffith, David Bush, Charles L. Liotta, and Charles A. Eckert investigate mixtures of supercritical CO2 and short-chain alcohols in J. Phys. Chem. A 2001, 105, 3947–3948. The combination of alcohol and CO2 leads to the / ns / tu formation of alkylcarboxylic acids.

[0030] The article "Diamines as switchable-hydrophilicity solvents with improved phase behaviour" in RSC Adv., 2018, 8, 27318 by Jesse R. Vanderveen, Jialing Geng, Susanna Zhang, and Philip G. Jessop investigates the use of diamines as switchable-hydrophilicity solvents (SHS) with improved partition coefficients. Several diamine SHSs are identified, and their properties are compared to those of monoamine SHSs. The comparisons include pKa values, partition coefficients, removal from hydrophobic liquids, switching rates, and temperature dependencies.

[0031] Yohann Coulier Alexander, R. Lowe, Alejandro Moreau, K. Ballerat-Busserolles, and J.-Yves Coxam describe ternary systems of an amine, water, and CO₂ in Fluid Phase Equilibria 2017, 431, 1–7: Liquid-liquid extraction in aqueous solutions of N-methylpiperidine (NMPD, tertiary amine) and 2-methylpiperidine (2MPD, secondary amine) was investigated as a function of CCh resolution. Novel experimental techniques were developed to determine the phase separation temperatures in aqueous solutions loaded with controlled amounts of gas. The experimental investigation with NMPD and 2MPD solutions shows opposing effects on the phase separation temperatures at CCh resolution. The influence of CO₂ on liquid-liquid extractions was discussed based on chemical reactions that occur in aqueous solutions of secondary and tertiary amines.

[0032] WO 2014 / 099268 describes CO2 separation from a gas stream using alkylamines (primary and secondary). These amines react directly with CO2 to form carbamates. The formation of carbamates from amines (including aromatic amines) and CO2 is also known from other sources; see, for example, 2024PF30058 - Foreign.

[0033] - 6 -

[0034] Hao-Yu Yuan, Jun-Chul Choi, Shun-ya Onozawa, Norihisa Fukaya, Seong, Jib Choi, Hiroyuki Yasuda, Toshiyasu Sakakura, Journal of CC utilization 2016, 16, 282 - 286.

[0035] Puxty, Graeme, Conway, Will, Yang, Qi, Bennett, Robert, Fernandes, Debra, Pearson, Pauline, Mäher, Dan, Feron, Paul describe the use of aromatic amines as CO2 absorbents in International Journal of Greenhouse Gas Control, 2019, 83, 11 - 19.

[0036] None of these references deal with the purification of crude process products from recycling processes of polyetherpolyol-based polyurethane products.

[0037] There was therefore a need for further improvements in the field of purifying crude process products from the recycling of polyether polyol-based polyurethane products. In particular, it would be desirable to efficiently remove as much as possible of any residual components of the other valuable product from the crude polyether polyol and amine fractions that regularly arise in such processes.

[0038] Taking this need into account, the present invention provides the following:

[0039] A process for the reprocessing of (at least) one (crude product) fraction containing (at least) one polyether polyol and (at least) one amine, wherein the (at least one) (crude product) fraction originates from a recycling process of a polyurethane product based on an isocyanate component and a polyol component comprising the (at least one) polyether polyol, the process comprising a step (a):

[0040] Treatment, particularly in the context of an extraction, of the (at least one) (crude product) fraction with carbon dioxide and a separation into an organic polyether polyol fraction and an aqueous amine fraction.

[0041] It was found, quite unexpectedly, that the use of carbon dioxide facilitates the separation of amines and polyether polyols. Without committing to a specific theory, it is suggested that this is due to the protonation of amines by carbonic acid and / or carbamic acids. The resulting NRiR2RsH + -Groups increase hydrophilicity, allowing the protonated amines to pass into the aqueous phase (the aqueous amine fraction) and thus be separated from the generally nonpolar polyether polyols. By heating and / or 2024PF30058 - Abroad

[0042] - 7 -

[0043] Upon reduction of the pressure of the separated aqueous amine fraction, the amine hydrogen carbonates or amine carbamate salts decompose, releasing carbon dioxide and regenerating the free amines.

[0044] Polyurethane products within the meaning of the present invention are the

[0045] Polyaddition products, which are formed by reacting polyhydric isocyanates (= isocyanate component of polyurethane production) with polyols

[0046] (= polyol component of polyurethane production). Polyurethane products generally contain, in addition to the above-described

[0047] Polyurethane base structure and other structures, for example urea-,

[0048] Isocyanurate, allophanate, and biuret structural units. The presence of such structures, deviating from the pure polyurethane base structure, alongside polyurethane structures does not exceed the scope of the present invention. Polyurethane products within the meaning of the present invention are preferably polyurethane foams obtained by reacting polyhydric isocyanates with polyols in the presence of a blowing agent, and in particular, rigid polyurethane foams. Within the scope of the present invention, a rigid polyurethane foam is understood to be a polyurethane foam that exhibits a compressive stress at 10% compression (do) of 10 kPa or more, as measured according to DIN EN 826:2013-05.

[0049] In the terminology of the present invention, the term polyols generally encompasses all polyols known to those skilled in the art in connection with polyurethane chemistry, such as, in particular, polyether polyols. The expression "a polyol" naturally also includes embodiments in which two or more different polyols are used in the production of a polyurethane product. Therefore, when, for example, "a polyether polyol" is mentioned below, this terminology naturally also includes embodiments in which two or more different polyether polyols are used in the production of a polyurethane product. The entirety of all polyols used in the production of a polyurethane product is referred to as the polyol component (of the polyurethane product). The polyol component of a polyurethane product to be treated according to the process of the invention always comprises at least one polyether polyol. The presence of further polyols (such as, for example, polyether polyols) does not affect the polyol component.B. Polyester polyols, polyether ester polyols and polyether carbonate polyols) is not excluded. 2024PF30058 - Abroad.

[0050] - 8 - In the terminology of the present invention, the term isocyanate includes all isocyanates known to those skilled in the art in connection with polyurethane chemistry and refers in particular to toluene diisocyanate (TDI), methylenediphenylene diisocyanate (mMDI), mixtures of methylenediphenylene diisocyanate and polymethylenepolyphenylene polyisocyanate, methylenedicyclohexyl 4,4'-diisocyanate (H12MDI), and mixtures thereof. The expression "one isocyanate" naturally also includes embodiments in which two or more different isocyanates (e.g., mixtures of MDI and TDI) are used in the manufacture of a polyurethane product, unless otherwise expressly stated, for example, by the phrase "exactly one isocyanate." The entirety of all isocyanates used in the manufacture of a polyurethane product is referred to as the isocyanate component (of the polyurethane product). The isocyanate component contains at least one isocyanate.

[0051] An amine corresponding to an isocyanate is that amine by whose phosgenation the isocyanate can be obtained according to R-NH2 + COCl2 ->RN=C=O + 2 HCl.

[0052] In the context of the present invention, a chemolysis product is understood to be the direct process product of a chemolysis, i.e., a chemical transformation of the polyurethane product involving the cleavage of the urethane bonds by reaction with an H-acidic compound (in particular water, amines, alcohols, amino alcohols or mixtures thereof).

[0053] In the context of the present invention, an organic chemolysis reagent means an organic compound that has functional groups which can react with urethane bonds by cleaving them, in particular alcohol and amine groups.

[0054] When the present invention refers to a device / assembly (e.g., in expressions such as "a reactor," etc.), this also includes embodiments in which several devices / assemblies of the aforementioned type are connected in series or in parallel (the example expression is therefore to be read as "at least one reactor"), unless expressly stated otherwise (e.g., by the phrase "exactly one"). The same applies to substances (see the above discussion of polyols and isocyanates).

[0055] The term distillation, as used in the context of the present invention, also includes rectification. 2024PF30058 - Foreign

[0056] - 9 -

[0057] Within the scope of the present invention, the extraction of a process product is understood to mean its mixing with an organic and / or aqueous extraction agent and subsequent phase separation.

[0058] Within the scope of the present invention, treatment of the (at least one) (crude product) fraction with carbon dioxide is understood to mean the targeted addition of carbon dioxide to the (crude product) fraction. The carbon dioxide formed in situ during the hydrolytic cleavage of urethane bonds is naturally, insofar as it does not outgas, "in contact" with the reacting mixture and the resulting crude product at least until the work-up of the immediate process product of the chemolysis; this "being in contact" is not in itself a carbon dioxide treatment within the meaning of the present invention, but can at most have a supporting effect.

[0059] The following is a brief summary of various possible embodiments of the invention:

[0060] In a first embodiment of the invention, which can be combined with all other embodiments, water is added to the (at least one) (crude product) fraction before or during the execution of step (a).

[0061] In a second embodiment of the invention, which can be combined with all other embodiments, an organic solvent is added to the (at least one) (crude product) fraction before or during the execution of step (a).

[0062] In a third embodiment of the invention, which is a particular embodiment of the second embodiment, the organic solvent is selected from (i) an ester (in particular a C2-Ce ester of acetic acid or an ethyl ester of a C3-Ce carboxylic acid or mixtures thereof; ethyl acetate is particularly preferred), (ii) an aromatic hydrocarbon (in particular xylene, toluene or benzene, or mixtures thereof), (iii) a halogenated aliphatic or aromatic hydrocarbon (in particular dichloromethane, chloroform, monochlorobenzene, dichlorobenzene or mixtures thereof), (iv) an ether (in particular aliphatic ethers such as diethyl ether, diisopropyl ether, tert-butyl methyl ether or mixtures thereof) or (v) mixtures of two or more of the aforementioned organic solvents.

[0063] In a fourth embodiment of the invention, which can be combined with all other embodiments, the (at least one) 2024PF30058 - Abroad

[0064] - 10 -

[0065] (Raw product) fraction washed with water without the addition of carbon dioxide before carrying out step (a).

[0066] In a fifth embodiment of the invention, which can be combined with all other embodiments, provided that these do not exclude the use of substantial amounts of water in the splitting of the polyurethane product, the recycling process comprises a reaction (= chemolysis) of the polyurethane product with water with (so-called hydroalcohollysis or aminohydrolysis) or without (hydrolysis) the addition of an organic chemolysis reagent to obtain an amine-containing chemolysis product.

[0067] In a sixth embodiment of the invention, which is a particular embodiment of the fifth embodiment, the amine-containing chemolysis product or a process product obtained from it by distilling off components that boil more easily than the (at least one) polyether polyol and the (at least one) amine is subjected to step (a) (= carbon dioxide treatment of the amine-polyether polyol mixture obtained in the chemolysis without prior separation of the same into an amine-rich phase and a polyether polyol-rich phase; the (at least one) (crude product) fraction within the meaning of the invention is therefore, in this embodiment, the amine-containing chemolysis product itself or the process product remaining after distillation containing the amines and polyether polyols formed in the chemolysis).

[0068] In a seventh embodiment of the invention, which is a further particular embodiment of the fifth embodiment, (at least) a process product obtained by further processing of the amine-containing chemolysis product comprising a phase separation of the same or (at least) an extraction of the same with an organic and / or aqueous extraction agent is subjected to step (a) (= carbon dioxide treatment after a pre-separation of the amine-polyetherpolyol mixture obtained in the chemolysis into an amine-rich phase and a polyetherpolyol-rich phase, wherein one or both of these can be a (crude product) fraction within the meaning of the invention).

[0069] In an eighth embodiment of the invention, which is a particular embodiment of the seventh embodiment, the further processing of the amine-containing chemolysis product comprises distilling off components that boil more easily than the (at least one) polyether polyol and the (at least one) amine.

[0070] In a ninth embodiment of the invention, which is a further special embodiment of the seventh embodiment, components that boil at a lower temperature than the (at least one) polyether polyol and the (at least one) amine are used according to 2024PF30058 - Abroad

[0071] - 11 -

[0072] Performing step (a) distilling from the aqueous amine fraction and / or the organic polyether polyol fraction.

[0073] In a tenth embodiment of the invention, which can be combined with all other embodiments, provided that these do not involve the use of substantial amounts of water in the cleavage of the polyurethane product, the recycling process comprises reacting the polyurethane product with an organic chemolysis reagent (without the presence of substantial amounts of water) to obtain a carbamate- and / or urea-containing chemolysis product and separating the same into a first phase containing carbamates and / or ureas and a second phase containing polyether polyols, wherein the second phase containing polyether polyols is subjected to step (a) for the separation of amines contained therein (the second phase containing polyether polyols is thus, in this embodiment, a (crude product) fraction within the meaning of the invention, which does not preclude the presence of further (crude product) fractions within the meaning of the invention).

[0074] In an eleventh embodiment of the invention, which can be combined with all other embodiments provided that they do not involve the use of substantial amounts of water in the cleavage of the polyurethane product, the recycling process comprises reacting the polyurethane product with an organic chemolysis reagent (without the presence of substantial amounts of water) to obtain a carbamate- and / or urea-containing chemolysis product and separating the same into a first phase containing carbamates and / or ureas and a second phase containing polyether polyols, comprising hydrolysis of the first phase containing carbamates and / or ureas to obtain an amine-containing phase, wherein the amine-containing phase or a process product obtained from it by distilling off organic chemolysis reagent is subjected to step (a) for the separation of polyether polyols contained therein (the amine-containing phase or a process product obtained from it by distilling off organic chemolysis reagent).The process product obtained by distilling off organic chemolysis reagent is therefore, in this embodiment, a (crude product) fraction within the meaning of the invention, which does not preclude the presence of further (crude product) fractions within the meaning of the invention.

[0075] In a twelfth embodiment of the invention, which is a particular embodiment of the eleventh, the hydrolysis of the phase containing carbamates and / or urea is carried out with the addition of a catalyst. 2024PF30058 - Abroad

[0076] - 12 - In a thirteenth embodiment of the invention, which is a particular embodiment of the tenth, eleventh or twelfth embodiment, the separation of the carbamate and / or urea-containing chemolysis product comprises a phase separation of the same or (at least) an extraction of the same with an organic and / or aqueous extraction agent.

[0077] In a fourteenth embodiment of the invention, which can be combined with all embodiments providing for the use of an organic chemolysis reagent in the recycling process, the organic chemolysis reagent comprises (in particular: is) (i) an alcohol, (ii) a primary or secondary amine, (iii) an amino alcohol with a primary or secondary amino group, or (iv) a mixture of two or more of the aforementioned organic chemolysis reagents.

[0078] In a fifteenth embodiment of the invention, which can be combined with all other embodiments, the process comprises a reaction of the polyurethane product with the addition of a catalyst.

[0079] In a sixteenth embodiment of the invention, which can be combined with all other embodiments, the treatment of the (at least one) (crude product) fraction with carbon dioxide in step (a) is carried out (carbon dioxide is added in such an amount) that a pressure of 10 bar to 70 bar, preferably 25 bar to 60 bar, is established in a gas space above the (crude product) fraction, wherein the mole fraction of carbon dioxide in the gas phase is 80% to 100%.

[0080] In a seventeenth embodiment of the invention, which is a particular embodiment of the sixteenth embodiment, a pressure of 10 bar to 70 bar, preferably 25 bar to 60 bar, is maintained until the separation of the carbon dioxide-treated (at least one) (crude product) fraction into the organic polyether polyol fraction and the aqueous amine fraction has been achieved.

[0081] In an eighteenth embodiment of the invention, which can be combined with all other embodiments, the treatment of the (at least one) (crude product) fraction with carbon dioxide in step (a) is carried out at a temperature of 4 °C to 50 °C.

[0082] In a nineteenth embodiment of the invention, which is a particular embodiment of the eighteenth embodiment, a temperature of 4 °C to 50 °C is maintained until the separation of the carbon dioxide-treated (at least one) (crude product) fraction into the organic polyether polyol fraction and the aqueous amine fraction has been achieved. 2024PF30058 - Abroad

[0083] - 13 - In a twentieth embodiment of the invention, which can be combined with all other embodiments, the treatment of the (at least one) (crude product) fraction with carbon dioxide in step (a) is carried out for a period (reaction time or residence time) of 5 min to 180 min, preferably 10 min to 90 min.

[0084] In a twenty-first embodiment of the invention, which can be combined with all other embodiments, the isocyanate component comprises an isocyanate selected from (i) toluene diisocyanate (TDI), (ii) methylenediphenylene diisocyanate (mMDI), (iii) a mixture (MDI) of methylenediphenylene diisocyanate (mMDI) and polymethylenepolyphenylene polyisocyanate (pMDI), (iv) methylenedicyclohexyl 4,4'-diisocyanate (H12MDI) or (v) a mixture of two or more of the aforementioned isocyanates.

[0085] In a twenty-second embodiment of the invention, which can be combined with all other embodiments, the (at least one) polyether polyol comprises (at least) a polymer of propylene oxide and optionally further epoxides.

[0086] In a twenty-third embodiment of the invention, which is a particular embodiment of the twenty-second embodiment, the (at least one) polyether polyol is selected from (i) a polymer of propylene oxide alone, (ii) a polymer of propylene oxide and ethylene oxide or (iii) a mixture of (i) and (ii).

[0087] The embodiments and other possible configurations of the invention briefly described above will be explained in more detail below.

[0088] SELECTION AND PREPARATION OF POLYURETHANE PRODUCTS

[0089] The process according to the invention is particularly suitable for use in the recycling of polyurethane products whose isocyanate component comprises an isocyanate selected from (i) toluene diisocyanate (TDI), (ii) methylenediphenyl diisocyanate (mMDI), (iii) a mixture (MDI) of methylenediphenyl diisocyanate (mMDI) and polymethylenepolyphenyl polyisocyanate (pMDI), (iv) methylenedicyclohexyl 4,4'-diisocyanate (H12MDI), or (v) a mixture of two or more of the aforementioned isocyanates. Particularly preferably, the isocyanate component (iii) comprises MDI, and most preferably, no other isocyanates are present besides MDI. With regard to the polyol component, it is preferred that the at least one polyether polyol is a polymer of propylene oxide and optionally further epoxides. 2024PF30058 - Foreign

[0090] - 14 - comprises. Particularly preferably, the at least one polyether polyol is selected from (i) a polymer of propylene oxide alone, (ii) a polymer of propylene oxide and ethylene oxide, or (iii) a mixture of (i) and (ii). As already mentioned, the polyol component may also contain other polyols in addition to at least one polyether polyol. Preferably, however, this is not the case; that is, preferably the polyol component comprises only polyether polyols.

[0091] Preferably, the polyurethane product is a polyurethane foam, and more preferably a rigid polyurethane foam.

[0092] The polyurethane product can be a used (so-called end-of-life) material. However, it can also be waste from the production of new polyurethane products. In the latter case, the chemical nature of the polyol component (as well as that of the isocyanate component) used in the production is, of course, known.

[0093] In the case of reusing a used polyurethane product, suitable sorting ensures, in particular, that it is a polyurethane product suitable for the purposes of the process according to the invention (i.e., one whose polyol component contains at least one polyether polyol). Knowing the original application of a used polyurethane product to be recycled, it will generally be known whether or not polyether polyols were used in its manufacture. The same applies, of course, to the type of isocyanate component. Therefore, by collecting different types of polyurethane separately, the identification of suitable polyurethane products can be easily ensured.If the properties of an available polyurethane product are not precisely known (for example, because it is a used polyurethane product of unspecified origin), this can be determined analytically. The composition of a polyurethane product can be qualitatively determined using ATR infrared spectroscopy (ATR = attenuated total reflection). All polyether polyurethanes are characterized by their COC vibrational band at 1100 cm⁻¹. 1 out. If propylene oxide polyethers are present, then at 2960 cm 1 the typical CH3 stretching vibration band is present. The IR spectrum also provides information about whether the polyurethane product is partially or completely MDI-based, as such polyurethane products exhibit characteristic bands at 1410 cm⁻¹. 1 , 1010 cm 1 and 510 cm 1Identifiable. Partially or completely TDI-based polyurethane products can be identified after chemical cleavage of the polyurethane product with a moist methanolic KOH solution. T It can be detected by H-NMR spectroscopy. The methyl group of the TDA formed during cleavage is located (measured in CDCH; chemical shift relative to 2024PF30058 - Abroad)

[0094] - 15 -

[0095] The residual proton signal is approximately 2.10 ppm for the 2,4-isomer and approximately 1.97 ppm for the 2,6-isomer. The aromatic range of 2,4-TDA extends from 6.0 ppm to 7.0 ppm, and that of 2,6-TDA from 6.2 ppm to 7.0 ppm.

[0096] The actual chemical recycling of the polyurethane product is preferably preceded by preparatory steps. These include, in particular, the sorting already mentioned and mechanical shredding.

[0097] PERFORMANCE OF CHEMOLYSIS

[0098] The (raw product) fraction to be treated with the inventive method can originate from a wide variety of chemical recycling processes for polyurethane products:

[0099] In one variant, the recycling process involves the formation of amines through the reaction (chemolysis) of the polyurethane product with water. This reaction can occur in the presence of an (alcoholic or amine) organic chemolysis reagent (so-called hydroalcohollysis or aminohydrolysis), but also in the absence of such a reagent ("pure" hydrolysis). In either case, an amine-containing chemolysis product is obtained. Suitable organic chemolysis reagents include, in particular, (i) alcohols, (ii) primary or secondary amines, (iii) amino alcohols with primary or secondary amino groups, or (iv) mixtures thereof.

[0100] In one embodiment of this variant, the amine-containing chemolysis product, optionally after distillative separation of components that boil at a lower rate than the at least one polyether polyol and the at least one amine, is subjected to step (a). Thus, prior to step (a), the amine-polyether polyol mixture obtained in the chemolysis is not pre-separated into an amine-rich phase and a polyether polyol-rich phase. The at least one (crude product) fraction within the meaning of the invention is therefore, in this embodiment, either the amine-containing chemolysis product itself (i.e., the immediate, "crude" process product of the chemolysis) or the process product remaining after distillation of volatile components, containing the amines and polyether polyols formed in the chemolysis.In a particular embodiment of this process, the carbon dioxide can be added during the ongoing chemolysis, especially when dealing with polyurethane products that can be hydrolytically cleaved under weakly acidic conditions without the use of a basic catalyst. 2024PF30058 - Foreign.

[0101] - 16 - In another embodiment of the first variant, the amine-containing chemolysis product is separated into an amine-rich and a polyether polyol-rich phase, and one or both of the phases thus obtained are subjected to step (a) (i.e., one or both of them can be a (crude product) fraction within the meaning of the invention). In the simplest case, the amine-containing chemolysis product separates spontaneously into an amine-rich and a polyether polyol-rich phase. However, depending on the precise nature of the polyurethane product to be recycled and the chemolysis process employed, it may be helpful to assist this separation by extraction with an organic and / or aqueous extraction agent.In this embodiment, step (a) is carried out after a pre-separation of the amine-polyetherpolyol mixture obtained in the chemolysis into an amine-rich phase and a polyetherpolyol-rich phase, wherein one or both of these can be a (crude product) fraction within the meaning of the invention.

[0102] In this embodiment, volatile components that boil more easily than the (at least one) polyether polyol and the (at least one) amine can also be removed by distillation, namely directly from the amine-containing chemolysis product, from the amine-rich and / or the polyether polyol-rich phase before carrying out step (a), or also from the aqueous amine fraction obtained in step (a) and / or from the organic polyether polyol fraction.

[0103] In a second variant, the recycling process involves reacting the polyurethane product with an organic chemolysis reagent to obtain a carbamate- and / or urea-containing chemolysis product (i.e., the chemolysis is carried out without substantial amounts of water) and separating this product into a first phase containing carbamates and / or ureas and a second phase containing polyether polyols. This separation can occur through spontaneous phase separation (so-called split-phase glycolysis) or be aided by extraction processes (for example, as described in WO 2020 / 260387 Al and WO 2022 / 063764 Al). The same organic chemolysis reagents are suitable as those described above for the first variant.

[0104] In both variants, the conversion of the polyurethane product can be carried out with the addition of a catalyst. Suitable catalysts include, for example, a hydroxide (especially an alkali metal or alkaline earth metal), a carboxylate (especially an acetate), a tin compound (especially dibutyltin dilaurate or tin(II) octoate [= tin(II) 2-ethylhexanoate]), or a 2024PF30058 - Abroad

[0105] - 17 -

[0106] Zinc compound (in particular zinc acetate), a (in particular alkali metal or alkaline earth metal) carbonate, a (in particular alkali metal or alkaline earth metal) hydrogen carbonate, an (in particular alkali metal or alkaline earth metal) orthophosphate, a (in particular alkali metal or alkaline earth metal) monohydrogen orthophosphate, an (in particular alkali metal or alkaline earth metal) orthovanadate, a titanium alkoxide, a tertiary amine, cesium fluoride or a mixture of two or more of the aforementioned chemolysis catalysts.

[0107] In one embodiment of the second variant, the second phase, containing polyether polyols, is subjected to step (a) to separate the amines contained therein (the second phase, containing polyether polyols, is thus a (crude product) fraction within the meaning of the invention in this embodiment, which does not preclude the presence of further (crude product) fractions within the meaning of the invention). The first phase, containing carbamates and / or ureas, can be further processed in various ways; for example, carbamates and ureas can be thermally converted into isocyanates and alcohols or amines using processes known per se, optionally with the aid of catalysts. If such thermal cleavage for the production of isocyanates is desired, it is recommended to carry out the chemolysis with an alcohol so that the first phase contains predominantly or completely carbamates.The first phase, containing carbamates and / or ureas, can also be hydrolyzed, releasing the corresponding amines, which is preferred. The amine-containing phase formed can then, optionally after distilling off the organic chemolysis reagent, be subjected to step (a) to separate any residual polyether polyols contained therein. In this embodiment, the amine-containing phase, or the process product obtained from it by distilling off the organic chemolysis reagent, is therefore a (crude product) fraction within the meaning of the invention, which does not preclude the presence of further (crude product) fractions within the meaning of the invention. The hydrolysis of the carbamate and / or urea-containing phase can be aided by the addition of a catalyst.Suitable catalysts include, for example, a (especially alkali metal or alkaline earth metal) hydroxide, a (especially alkali metal or alkaline earth metal) carboxylate (especially acetate), a tin compound (especially dibutyltin dilaurate or tin(II) octoate [= tin(II)-2-ethylhexanoate]), a zinc compound (especially zinc acetate), a (especially alkali metal or alkaline earth metal) carbonate, a (especially alkali metal or alkaline earth metal) hydrogen carbonate, an (especially alkali metal or alkaline earth metal) orthophosphate, a (especially alkali metal or alkaline earth metal) monohydrogen orthophosphate, an (especially alkali metal or 2024PF30058 - Abroad.

[0108] - 18 -

[0109] alkaline earth metal (orthovanadate), a titanium alkoxide, a tertiary amine, cesium fluoride, or a mixture of two or more of the aforementioned chemolysis catalysts.

[0110] To avoid undesirable side reactions, chemolysis is preferably carried out in the absence of oxygen. Polyurethane foams are preferably deoxygenated down to the cell structure. For this purpose, the cells of the polyurethane foam can be degassed by a series of strong pressure reductions and increases, or mechanically compressed and forced into an area of ​​reduced pressure (see WO 2022 / 128871 Al for details).

[0111] PERFORMANCE OF CARBON DIOXIDE TREATMENT (STEP (a))

[0112] Depending on the type of polyurethane product and the execution of the chemolysis, it may be useful to add water to the (at least one) (crude product) fraction before or during step (a) to facilitate the formation of an aqueous amine fraction.

[0113] The carbon dioxide used can originate from various sources. Examples include carbon dioxide generated during industrial processes and recovered from the exhaust gas stream, for instance, via amine scrubbing and / or pressure swing adsorption. Another example is chemical processes such as decarboxylation reactions, where carbon dioxide can already be obtained in high purity from the product gas outlet. Carbon dioxide formed during the hydrolytic cleavage of urethane bonds is also particularly suitable. This can be removed from the reaction system, compressed if necessary, and fed into step (a) along with additional carbon dioxide from other sources.

[0114] The carbon dioxide treatment of the (crude product) fractions according to the invention preferably comprises the addition of an organic solvent. This addition can be carried out before or during step (a). Suitable organic solvents include, in particular, (i) esters (especially C2-ce esters of acetic acid, ethyl esters of a C2-ce carboxylic acid, or mixtures thereof; ethyl acetate is particularly preferred), (ii) aromatic hydrocarbons (especially xylene, toluene, or benzene, or mixtures thereof), (iii) halogenated aliphatic or aromatic hydrocarbons (especially dichloromethane, chloroform, monochlorobenzene, dichlorobenzene, or mixtures thereof), (iv) ethers (especially aliphatic ethers such as diethyl ether, diisopropyl ether, tert-butyl methyl ether, or mixtures thereof), or (v) mixtures of two or more of the aforementioned organic solvents. 2024PF30058 - Foreign

[0115] - 19 -

[0116] In some circumstances, it may be advantageous to precede the carbon dioxide treatment of at least one crude product fraction with a water wash without the addition of carbon dioxide (neutral wash). This is particularly appropriate if the polyol component also includes comparatively hydrophilic polyether polyols, i.e., polyether polyols with a short chain length and / or high functionality. These can be removed from the amine-polyol mixture by such a neutral wash. The crude product fraction washed in this way (largely or completely free of hydrophilic polyether polyols) is then subjected to step (a), which successfully separates amines from more nonpolar polyether polyols (i.e., those with a long polymer chain and / or low functionality).

[0117] Preferably, the treatment of the (at least one) (crude product) fraction with carbon dioxide in step (a) is carried out (carbon dioxide is added in such a quantity) that a pressure of 10 bar to 70 bar, preferably 25 bar to 60 bar, is established in a gas space above the (crude product) fraction, and the mole fraction of carbon dioxide in the gas phase is 80% to 100%. The pressure (= total pressure) can be determined using commercially available pressure gauges. For the purposes of the present invention, the mole fraction of carbon dioxide is calculated from the known quantity of carbon dioxide added and the also known quantity of an optionally added inert gas (in particular nitrogen). Any evaporated components of the liquid phase are negligible and are not taken into account in the calculation.An increased pressure should be maintained until the aqueous amine fraction has been separated; preferably, the separation takes place at the same pressure as the actual carbon dioxide treatment.

[0118] The temperature during the treatment of the (at least one) (crude product) fraction with carbon dioxide in step (a) is preferably 4 °C to 50 °C. An increase in temperature should be avoided until the aqueous amine fraction has been separated; preferably, the separation takes place at the same temperature as the actual carbon dioxide treatment.

[0119] Preferably, the treatment of the (at least one) (crude product) fraction with carbon dioxide in step (a) is carried out for a period (reaction time or residence time) of 5 min to 180 min, preferably 10 min to 90 min.

[0120] Step (a) can be carried out discontinuously or continuously. A discontinuous procedure can be performed in a pressure-resistant vessel with a mixing function (e.g., a pressure reactor) and a device for 2024PF30058 - Abroad

[0121] - 20 - the separation of the phases takes place. Continuous processing can be carried out in pressure-stable extraction units with mixing and settling functions (e.g., a pressure-stable mixer-setter).

[0122] If the carbon dioxide treatment during chemolysis is carried out with water before the end of the chemolysis process, a three-phase reaction system is present (solid [polyurethane], organic phase, aqueous phase). In this embodiment, it is preferred to continuously feed polyurethane (e.g., via screw conveyor or as a slurry), optionally the aforementioned organic solvent and water, and optionally an organic chemolysis reagent into the reaction, and to continuously remove and separate the resulting organic and aqueous phases. A continuous stirred tank reactor (CSTR), particularly one equipped with pressure-maintaining valves and operated under isobaric conditions, is suitable as a reactor system.The CCh content in the system results from external addition of CO2 (especially at the beginning of the reaction to reach the desired pressure level) and CO2 that forms in situ during the hydrolytic cleavage of the urethane bonds.

[0123] 2024PF30058 - Abroad

[0124] Examples:

[0125] chemicals

[0126] 4,4'-Methylenediphenylenediamine (4,4'-mMDA), 98% Sigma Aldrich

[0127] 2,4-Toluenediamine (2,4-TDA), 98% Sigma Aldrich

[0128] Ethyl acetate, 99.9% VWR

[0129] Polyol 1 (1) Covestro Deutschland AG

[0130] Polyol 2 (2) Covestro Deutschland AG

[0131] Polyol 3 (3) Covestro Deutschland AG

[0132] Polyol 4 (4) Covestro Deutschland AG

[0133] Polyol 5 (5) Covestro Deutschland AG

[0134] "MDA-61" (6)Covestro Deutschland AG

[0135] (1) Polyether polyol (OHZ: 48 mg / g; functionality (F) = 2.8; propylene oxide (PO) content: 87%); is typically used for the production of soft foams - Polyol 1.

[0136] (2) Polyether polyol (OHZ: 400 mg / g; F = 4.0; PO content: 75%); is typically used for the production of rigid foams - Polyol 2.

[0137] (3) Polyether polyol (OHZ: 477 mg / g; F = 5.5; PO content: 74%); is typically used for the manufacture of rigid foams - Polyol 3.

[0138] (4) Polyether polyol (OHZ: 112 mg / g; F = 2.0; PO content: 92%); is typically used for the manufacture of rigid foams - Polyol 4.

[0139] (5) Polyether polyol (OHZ: 450 mg / g; F = 4.7; PO content: 66%); is typically used for the manufacture of rigid foams - Polyol 5.

[0140] (6) Mixture (MDA) of methylenediphenylenediamine (mMDA) and polymethylenepolyphenylenepolyamine (pMDA).

[0141] Polyols used

[0142] Polyol mixture A: Four different polyols were mixed in the following proportions to form a typical polyol component (“Polyol mixture A”) for a polyurethane rigid foam formulation.

[0143] Polyol 2 25 wt%

[0144] Polyol 3 34 wt%

[0145] Polyol 4 7 wt%

[0146] Polyol 5 34 wt%

[0147] Polyol B: Polyol 1 was used as a representative example of a soft foam polyether polyol ("Polyol B"). 2024PF30058 - Abroad

[0148] Foam formulations used

[0149] Foam recipe i: Formulation of the one implemented in examples 9 and 10

[0150] Polyurethane rigid foam (figures are mass quantities):

[0151] Polyol 3 and Polyol 5 25

[0152] Polyol 2 9.3

[0153] Polyol 4 2.6

[0154] Water 0.9

[0155] Siloxane additive (1) 0.7

[0156] Amine catalysts (2) ' (3) 0.7

[0157] Cyclopentan (4) 5.4

[0158] “Desmodur 44V20L” (5) 55.4

[0159] Key figure (6) 108

[0160] (1) Polyethersiloxane additive from Evonik AG.

[0161] (2) Amine catalyst from Covestro Deutschland AG.

[0162] (3) Amine catalyst from Evonik AG.

[0163] (4) Physical propellant.

[0164] (5) Desmodur 44V20L is a mixture of pMDI and mMDI from Covestro Deutschland AG.

[0165] (6) Amount of NCO groups used per 100 mol of OH groups.

[0166] Analytics

[0167] 1 H-NMR spectroscopy

[0168] The measurements were performed on a Bruker Avance III 400 (400 MHz); the calibration of the chemical shifts was performed relative to the residual proton signal (DMSO-d6: Δ1H = 2.50 ppm).

[0169] To determine the compositions of the individual phases after the extraction step, the amine and polyether polyol fractions in the two phases were determined using a calibration curve.

[0170] For the investigation of mixtures of 4,4'-mMDA / polyol mixture A or MDA / polyol mixture A or hydrolysates of PUR rigid foams (Examples 1 to 8), the proton signals in the aromatic region were integrated to determine the amine / polyol mass ratios. In the case of polyether polyols with ortho-TDA as the starter molecule, these were adjusted for the contribution of ortho-TDA in 2024PF30058 - Abroad

[0171] - 23 - corrected this signal range. The -CHa signal in the aliphatic region was integrated as representative of the polyether polyol (mixture) used.

[0172] For the investigation of mixtures of TDA and polyol B (Examples 9 and 10), the proton signal of the aromatic CFh group was integrated to determine the amine / polyol mass ratios. The -CFh signal in the aliphatic region was integrated as representative of the polyether polyol (mixture) used.

[0173] General work regulations

[0174] Abbreviations

[0175] Name Phase Comments

[0176] Aqueous phase Neutral, without CO2

[0177] B Organic Phase See details of the corresponding aqueous phase

[0178] C Aqueous phase In the presence of additional CO2

[0179] Extraction experiments

[0180] Experimental method for separating amines (mMDA or mixtures of mMDA and pMDA) and polyether polyols

[0181] (m)MDA / Polyol mixture A: 1.2 g each of 4,4'-mMDA or "MDA-61" are mixed with 0.8 g of polyol mixture A. The resulting mixture is dissolved in 150 ml of ethyl acetate. Then, 150 ml of deionized water is added to the mixture. First, a neutral aqueous extraction is carried out in a separatory funnel. The organic, ethyl acetate-containing phases are extracted with 150 ml of water each (shaking time 1 min; phase separation 10 min). Depending on the number of extraction steps performed, the aqueous phases (Al, A2, A3) are obtained. The organic phase B ("Bl" for the first extraction with water, "B2" for the second, etc.) is then transferred to a pressure-resistant steel reactor for extractions in the presence of CO2, followed by the addition of 150 ml of deionized water.

[0182] The reactor is closed, pressurized with 10 bar CO2, and then depressurized. This process is repeated twice more. The reactor is then pressurized with CCh gas at the desired temperature (see Table 1 for exact pressure and temperature values). The reaction mixture is then heated under CCh pressure at the respective 2024PF30058 - Abroad

[0183] - 24 - The mixture is stirred at the specified temperature for 1 h (600 rpm). After 1 h, stirring is stopped and the reaction mixture is allowed to stand under pressure for 15 min to allow phase separation (which is also carried out under pressure). The CO2-enriched aqueous phase C2 of this second extraction is collected in a bottle connected to the reactor vessel via a dip tube, and the mass of C2 is determined. Subsequently, all volatile components of C2 are removed using a rotary evaporator at 40 °C and a pressure initially of approximately 240 mbar, later reduced to approximately 20 mbar. The organic phase B2 remaining in the reactor vessel is optionally used for further extraction experiments by adding fresh portions (150 ml) of water (identical procedure for further aqueous-organic extraction in the presence of CCh to obtain phases C3, C4, and C5, respectively).B3, B4) and at the end of all extraction attempts weighed and freed from all volatile components using a rotary evaporator.

[0184] All residues are measured gravimetrically after the volatile components have evaporated and are treated with 1 The samples were examined using H-NMR spectroscopy. The respective compositions were determined using the method described above.

[0185] To compare the influence of CO2 on the separation of amines / polyols, similar experiments were carried out under identical conditions without the presence of CCh gas.

[0186] 2,4'-TDA / Polyol B: 1.4 g of 2,4'-TDA was mixed with 2.6 g of polyol B, corresponding to a typical composition obtained by hydrolysis of a polyurethane flexible foam product. The subsequent extraction procedure is carried out analogously to the procedure described above for (m)MDA / polyol mixture A. In contrast, in the case of CCh-assisted extraction (Example 10), no prior neutral aqueous extraction is performed. The detailed conditions and extraction steps are listed in detail in the tables accompanying the examples below.

[0187] The hydrolysis experiments were carried out in a 300 ml stainless steel pressure reactor with a glass insert. The PU foam (composition see foam recipe 1) is first crushed with a mixer, and then 10 g of the crushed foam are placed in the reactor along with 30 g of water. The reactor is then filled with N2 at 2024PF30058 - Abroad

[0188] - 25 -

[0189] The reactor, inertized at room temperature and with a set ISh partial pressure of 10 bar, is placed in an aluminum block heated to reaction temperature. The reaction mixture is stirred at 900 rpm for 4 hours. After the reaction is complete, the reactor is cooled in an ice bath. The pressure is then released and the reactor is opened. The resulting heterogeneous multiphase product mixture is reconstituted with 50 ml of THF, and all volatile components are subsequently removed under vacuum. The remaining residue serves as the starting material for the extraction experiments of hydrolyzed PU foam. Table 1: Overview of the experiments carried out according to the invention and comparative examples. 2024PF30058 - Abroad

[0190] - 26 -

[0191] Examples 1 to 3: Organic aqueous extraction of 4,4-mMDA / polyol mixture A

[0192] Table 2: Results of examples 1 to 3:

[0193] [a] Mass ratio.

[0194] [b] The range reflects the experimental variability. It can be seen that in the first neutral extraction for the aqueous phase, a high selectivity for the polyols is observed (see phase Al). Here, short-chain polyols with high functionality are washed out of the amine-polyol mixture, while longer-chain polyols with lower functionality remain in the organic phase along with the majority of the amines. In the subsequent stages, increasingly mixed process products without good separation performance are obtained (see phases A2 and A3). The transfer of the amines into the aqueous phase, which would be the goal after the extensive removal of the short-chain, highly functional polyols in the first extraction, is not achieved in Example 1. Only the addition of CO2 in the second and third extractions leads to a significantly better selectivity for the amines, with a higher CCh partial pressure resulting in better separation performance (see Example 1).2 with example 3).

[0195] 2024PF30058 - Abroad

[0196] - TI -

[0197] Examples 4 to 6: Organic aqueous extraction of MDA-61 / polyol mixture A

[0198] Table 3: Results of examples 4 to 6:

[0199] [a] Mass ratio.

[0200] In all three cases, a significantly improved selectivity for the extraction of the amine into the aqueous phase was observed. With an increasing number of extraction steps, better separation performance was achieved.

[0201] Examples 7 and 8: Organic aqueous extraction of hydrolyzed PU foam

[0202] Table 4: Results of examples 7 and 8: [a] Mass ratio.

[0203] In the case of additional CO2 after an initial neutral aqueous extraction, improved selectivity for the extraction of the amine into the aqueous phase is observed. With an increasing number of extraction steps, better separation efficiency is achieved. After the third extraction, the amine / polyol ratio in Example 7 (comparison) is only 59 / 41, while in Example 8 it is 79 / 21. 2024PF30058 - Foreign

[0204] - 28 -

[0205] Examples 9 and 10: Organic aqueous extraction of 2,4-TDA / polyol B

[0206] Table 5: Results of examples 9 and 10:

[0207] [a] Mass ratio.

[0208] [b] Values ​​given are mass percentages. The sum of the recovery values ​​of the individual phases is normalized to 100%.

[0209] [c] The "total" recovery values ​​were determined based on the weight of the non-volatile components. The "amine" and "polyol" recovery values ​​reflect the analytical fraction in the respective phase relative to the original composition of the mixture. In the case of the relatively water-soluble TDA, only a small effect of CO2 on the selectivity for the extraction of the amine into the aqueous phase is observed (see phase Al with CI). However, the use of CO2 leads to a higher loading of the phases, which, in the described extraction sequence, results in complete separation with a very pure organic polyol phase (Ex. 10, B3). Using an analogous procedure without the addition of CO2, a pure organic polyol phase cannot be recovered (Ex. 9, B3).

Claims

2024PF30058 - Abroad - 29 - 1. A process for the recovery of a fraction containing a polyether polyol and an amine, wherein the fraction originates from a recycling process of a polyurethane product based on an isocyanate component and a polyol component comprising the polyether polyol, the process comprising a step (a): Treatment of the fraction with carbon dioxide and separation into an organic polyether polyol fraction and an aqueous amine fraction.

2. The method of claim 1, wherein water is added to the fraction before or during the execution of step (a).

3. The method of claim 1 or 2, wherein an organic solvent is added to the fraction before or during the execution of step (a).

4. The method of claim 3, wherein the organic solvent is selected from (i) an ester, (ii) an aromatic hydrocarbon, (iii) a halogenated aliphatic or aromatic hydrocarbon, (iv) an ether or (v) mixtures of two or more of the aforementioned organic solvents.

5. Method according to any one of claims 1 to 4, wherein the fraction is washed with water before carrying out step (a) without the addition of carbon dioxide.

6. A method according to any one of claims 1 to 5, wherein the recycling process comprises reacting the polyurethane product with water with or without the addition of an organic chemolysis reagent to obtain an amine-containing chemolysis product.

7. The method of claim 6, wherein the amine-containing chemolysis product or a process product obtained from it by distilling off components that boil more easily than the polyether polyol and the amine is subjected to step (a); or wherein a process product obtained by further processing of the amine-containing chemolysis product comprising a phase separation thereof or an extraction thereof with an organic and / or aqueous 2024PF30058 - Abroad - 30 - The process product obtained with the extraction agent is subjected to step (a).

8. A method according to any one of claims 1 to 5, wherein the recycling process comprises reacting the polyurethane product with an organic chemolysis reagent to obtain a carbamate and / or urea-containing chemolysis product and separating the same into a first phase containing carbamates and / or ureas and a second phase containing polyether polyols, wherein the second phase containing polyether polyols is subjected to step (a) for the separation of amines contained therein.

9. A process according to any one of claims 1 to 5 or 8, wherein the recycling process comprises reacting the polyurethane product with an organic chemolysis reagent to obtain a carbamate and / or urea-containing chemolysis product and separating the same into a first phase containing carbamates and / or ureas and a second phase containing polyether polyols, comprising hydrolysis of the first phase containing carbamates and / or ureas to obtain an amine-containing phase, wherein the amine-containing phase or a process product obtained from it by distilling off organic chemolysis reagent is subjected to step (a) for the separation of polyether polyols contained therein.

10. The method of claim 8 or 9, wherein the separation of the carbamate and / or urea-containing chemolysis product comprises phase separation of the same or extraction of the same with an organic and / or aqueous extraction agent.

11. Method according to one of the preceding claims, wherein the treatment of the fraction with carbon dioxide in step (a) is carried out such that a pressure of 10 bar to 70 bar is established in a gas space above the fraction and the mole fraction of carbon dioxide in the gas phase is 80% to 100%.

12. Method according to claim 11, wherein a pressure of 10 bar to 70 bar is maintained until the separation of the fraction treated with carbon dioxide into the organic polyether polyol fraction and the aqueous amine fraction has been achieved. 2024PF30058 - Abroad - 31 - 13. Method according to one of the preceding claims, wherein the treatment of the fraction with carbon dioxide in step (a) is carried out at a temperature of 4 °C to 50 °C.

14. Method according to claim 13, wherein a temperature of 4 °C to 50 °C is maintained until the separation of the fraction treated with carbon dioxide into the organic polyether polyol fraction and the aqueous amine fraction has been achieved.

15. A method according to any of the preceding claims, wherein the isocyanate component comprises an isocyanate selected from (i) toluene diisocyanate, (ii) methylenediphenylene diisocyanate, (iii) a mixture of methylenediphenylene diisocyanate and polymethylenepolyphenylene polyisocyanate, (iv) methylenedicyclohexyl 4,4'-diisocyanate or (v) a mixture of two or more of the aforementioned isocyanates, and / or wherein the polyether polyol comprises a polymer of propylene oxide and optionally further epoxides.

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