Depolymerization process for polyurethane materials and products thereof

Abstract

The present invention generally relates to the field of purification or recycling of waste polymers. More specifically, an aspect of the present invention relates to a process for the depolymerization of a polyurethane material, the process comprising the steps of contacting the polyurethane material with a depolymerization agent comprising an amine and / or alkanolamine to obtain a depolymerization mixture; heating the depolymerization mixture to a temperature of between 80.0 and 250.0 °C; allowing the formation of at least three phase-separated liquids; and separating the at least three phase-separated liquids; wherein the at least three phase-separated liquids comprise a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds.

Description

[0001] DEPOLYMERIZATION PROCESS FOR POLYURETHANE MATERIALS AND PRODUCTS THEREOF

[0002] FIELD OF THE INVENTION

[0003] The technology of the present invention generally relates to the field of purification or recycling of waste polymers. More specifically, the present invention relates to a process for the depolymerization of a polyurethane material. The present invention further relates to a method for the manufacturing of a recycled polyurethane material.

[0004] BACKGROUND

[0005] Polyurethane (PU) is a versatile polymer used in a wide range of applications, including foams, elastomers, coatings, adhesives, and sealants. Due to its extensive use, large amounts of PU waste are generated annually. This waste poses significant environmental challenges because PU is not biodegradable and its disposal in landfills or incineration is not sustainable. Therefore, recycling PU has become an essential area of research and development. Ideally improved recycling methods also reduce the energy intensity of material synthesis by recovering valuable chemical feedstock.

[0006] The most commonly studied PU recycling routes to date include mechanical recycling and chemical recycling. Mechanical recycling involves the grinding and processing of PU waste into smaller particles, such as a powder, which can then be used as fillers or reinforcements in new PU products. However, an important disadvantage of mechanical recycling is that it often results in lower quality materials.

[0007] To better preserve the quality of recycled material, chemical recycling is often proposed as a better solution. This method breaks down PU material into its original monomers or other valuable chemicals, which may then be used to prepare new PU materials. In particular, chemolysis techniques such as glycolysis, hydrolysis, aminolysis, or alcoholysis allow to cleave the chemical bonds within the polymer structure to recover its constituting monomers and other small molecules. Nevertheless, because PU materials are made from a variety of starting materials, including various isocyanates and polyols, traditional depolymerization approaches may lead to diverse and complex mixtures of chemical structures. These complex mixtures may become more difficult to purify, which significantly decreases its commercial utility.

[0008] In view of the above, there remains a need to address the aforementioned issues by providing an improved chemical recycling process of PU materials in order to produce chemicals with optimal commercial value. This is required in order to produce recycled PU materials that meet present quality standards. SUMMARY OF THE INVENTION

[0009] It has now been found that some or all of the above challenges can be addressed, and objectives can be achieved, either individually or in any combination, by using the process for the depolymerization of PU material as described herein. Advantageously, the present depolymerization approach allows to form multiple phase-separated liquids which can provide a more efficient separation of various polyols and amine compounds formed during the recycling process. This is in stark contrast to depolymerization methods known in the art wherein typically all polyol compounds, irrespective of chemical structure, are concentrated in a single liquid phase.

[0010] Another advantage of the present process is that the energy consumption required for the separation of produced chemicals from the multiple phase-separated liquids may be significantly reduced compared to prior art methods.

[0011] Another advantage of the present process is that the polyols and amine compounds formed during the depolymerization process may be recovered with a high purity.

[0012] An overview of various aspects of the technology of the present invention is given hereinbelow, after which specific embodiments will be described in more detail. This overview is meant to aid the reader in understanding the technological concepts more quickly, but it is not meant to identify the most important or essential features thereof, nor is it meant to limit the scope of the present invention, which is limited only by the claims.

[0013] The present invention thus provides methods for recycling PU material, such as foams, which involve the depolymerization of the PU material, the separation of the polyols and the use of the polyols in the generation of recycled materials.

[0014] An aspect of the present invention relates to a process for the depolymerization of a polyurethane material derived from at least two different polyols, the process comprising the steps of: a) contacting the polyurethane material with a depolymerization agent comprising an amine and / or alkanolamine to obtain a depolymerization mixture; b) heating the depolymerization mixture to a temperature of between 80.0 and 250.0 °C; c) allowing the formation of at least three phase-separated liquids; and d) separating the at least three phase-separated liquids; wherein the at least three phase-separated liquids comprise a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds.

[0015] In particular embodiments, the present process is directed to the depolymerization of a polyurethane material made from at least two immiscible polyols, the process comprising the steps of: a) contacting the polyurethane material with a depolymerization agent comprising an amine and / or alkanolamine to obtain a depolymerization mixture; b) heating the depolymerization mixture to a temperature of from 80.0 to 250.0 °C; c) allowing the formation of at least three phase-separated liquids; and d) separating the at least three phase-separated liquids; wherein the at least three phase-separated liquids comprise a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds; and wherein the depolymerization agent is immiscible with each polyol

[0016] It has been found that most PU materials are made of different polyols to tailor their properties to specific applications. To meet specific requirements, often polyols of different chemical nature are used to create hard and soft, or phase-separated domains. The present inventors have found that the intrinsic complex, and multi-phase structure of PU materials can be employed in the physical separation of depolymerized products thereof. In particular, in the context of the present invention, a depolymerization agent comprising an amine and / or alkanolamine can be selected, which advantageously is immiscible with the different polyol fractions obtained after depolymerization. This allows for the generation of separate phases comprising each polyol type and a separate phase comprising the majority of the depolymerization agent, such that at least three phase-separated liquids are formed. In addition, it has been found that the envisaged depolymerization agent may advantageously aid in avoiding the cross-distribution of the produced polyols between the separate phases.

[0017] In particular embodiments, the depolymerization agent comprises an amine comprising at least one primary amino functional group and / or at least one secondary amino functional group, preferably wherein the amine is selected from the group consisting of pentane-l,5-diamine, (dibutyl)amine, dodecylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and mixtures thereof. In particular embodiments, the depolymerization agent comprises an alkanolamine comprising at least one hydroxyl functional group and at least one amino functional group, preferably wherein the alkanolamine has the following structural Formula (la) or (II)

[0018] (la), (II) wherein,

[0019] R3,R2, R3are each independently selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl, arylalkyl; X1is hydrogen; and X2, X3are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, and cycloalkyl; with the provision that at least one of X2, X3is hydrogen.

[0020] In particular embodiments, the depolymerization agent comprises an alkanolamine comprising at least one hydroxyl functional group and at least one amino functional group, preferably wherein the alkanolamine has the following structural Formula (I) wherein,

[0021] R1and R2are each independently selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl, and arylalkyl; and X is selected from the group consisting of hydrogen, alkyl, alkenyl, and cycloalkyl.

[0022] In particular embodiments, step a) comprises contacting the polyurethane material with the depolymerization agent comprising an amine and / or alkanolamine in a weight ratio of from 1.0:1.1 to 1.0:5.0 to obtain the depolymerization mixture. It has been found herein that an excess of depolymerization agent may advantageously provide for a more efficient depolymerization of the polyurethane material and improved formation of the phase-separated liquids.

[0023] In particular embodiments, step c) comprises cooling or allowing to cool, preferably cooling or allowing to cool to 20 °C.

[0024] In particular embodiments, the polyurethane material is a product obtained by reacting two or more polyols and one or more isocyanate compounds; and wherein the two or more polyols are immiscible. In particular embodiments, the polyurethane material is polyurethane scrap or foam; preferably obtained from car seats, sofa and bed matrasses and other cushioning material. The invention envisages the use of the methods of the invention for the depolymerization of both methylene diphenyl diisocyanate (MDI)-based and toluene diisocyanate (TDI)-based polyurethane material.

[0025] In particular embodiments, the one or more first polyols are a polyether polyol or an acrylic polyol, preferably a polyether polyol, and / or the one or more second polyols are a polyether polyol or an acrylic polyol, preferably a polyether polyol.

[0026] In particular embodiments, the one or more first polyols comprise -[OCHfCHajCHz]- as the main repeating unit and the one or more second polyols comprise -[OCHfCHajCHz]- and -[OCH2CH2]- as the main repeating units.

[0027] In particular embodiments, the one or more first polyols are propylene glycol and the one or more second polyols are a copolymer of ethylene oxide and propylene oxide, preferably a copolymer of ethylene oxide and propylene oxide with a high ethylene oxide content, such as at least about 50 wt.% of ethylene oxide, with wt.% relative to the total weight of the copolymer.

[0028] In particular embodiments, the difference in number average molecular weight (Mn) between the one or more first polyols and the one or more second polyols is at least 250 g / mol, or at least 500 g / mol, or at least 750 g / mol, or at least 1000 g / mol.

[0029] In particular embodiments, the one or more first polyols has a number average molecular weight (Mn) of at least 1500 g / mol.

[0030] In particular embodiments, the one or more amine compounds are selected from the group consisting of 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6- hexamethylenediamine, isophorone diamine, 2,3-diaminotoluene, 2,4-diaminotoluene, 3,4- diaminotoluene, 2,6-diaminotoluene, 4,4'-methylenedianiline, 2, 4' -methylenedianiline, 2,2'- methylenedianiline, oligomeric derivatives thereof and / or mixtures thereof.

[0031] In preferred embodiments, the one or more amine compounds are selected from the group consisting of 2,3-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 2,6-diaminotoluene, 4,4'- methylenedianiline, 2,4'-methylenedianiline, 2,2'-methylenedianiline, oligomeric derivatives thereof and / or mixtures thereof.

[0032] In particular embodiments, the present process further comprises the step of: e) isolating the one or more first and / or second polyols from the first and second liquid, thereby obtaining recycled polyols, and optionally isolating the one or more amine compounds from the third liquid, thereby obtaining recycled amine compounds.

[0033] A further related aspect of the present invention relates to a method for manufacturing a recycled polyurethane material, the method comprising the steps of: i) providing one or more recycled polyols obtained by means of the process for the depolymerization of a polyurethane material according to the present invention; ii) contacting the one or more recycled polyols with one or more isocyanate compounds, optionally in the presence of a catalyst, to form the recycled polyurethane material.

[0034] In particular embodiments, the present method comprises the steps of: i) depolymerizing a polyurethane material, made from at least two immiscible polyols, by means of the depolymerization process according to an aspect of the present invention or (preferred) embodiments thereof, thereby obtaining at least three phase-separated liquids comprising a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds; ii) isolating the one or more first and / or second polyols from the first and second liquid, thereby obtaining recycled polyols; iii) contacting the one or more recycled polyols with one or more isocyanate compounds, optionally in the presence of a catalyst, to form the recycled polyurethane material.

[0035] It should be noted that (preferred) embodiments and associated advantages of the process for the depolymerization of a polyurethane material according to the present invention are also (preferred) embodiments of the method for manufacturing a recycled polyurethane material according to the present invention and vice versa.

[0036] In preferred embodiments, the one or more isocyanate compounds are derived from one or more recycled amine compounds by means of the process for the depolymerization of a polyurethane material according to the present invention.

[0037] In preferred embodiments, the one or more isocyanate compounds are obtained by: isolating the one or more amine compounds from the third liquid (obtained by means of the present depolymerization process), thereby obtaining recycled amine compounds; and converting one or more recycled amine compounds into the corresponding isocyanate compound.

[0038] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, which illustrate, by way of example, the principles of the invention.

[0039] DETAILED DESCRIPTION OF THE FIGURES

[0040] The teaching of the application is illustrated by the following Figures which are to be considered as illustrative only and do not in any way limit the scope of the claims.

[0041] FIG. 1 represents a gel permeation chromatogram of three phase-separated liquids (layers) following the depolymerization of PU material PU-A according to the process as disclosed herein.

[0042] FIG. 2 represents a gel permeation chromatogram of three phase-separated liquids (layers) following the depolymerization of PU material PU-A after heating at 240.0 °C for 5 minutes and 30 minutes, respectively.

[0043] FIG. 3 represents a gel permeation chromatogram of three phase-separated liquids (layers) following the depolymerization of a PU material PU-A after heating at 160.0 °C for 30 minutes and 240.0 °C for 30 minutes, respectively.

[0044] FIG. 4 represents a gel permeation chromatogram of three phase-separated liquids (layers) following the depolymerization of PU material PU-B according to the process as disclosed herein.

[0045] FIG. 5 represents a gel permeation chromatogram of three phase-separated liquids (layers) following the depolymerization of PU material PU-C according to the process as disclosed herein.

[0046] DETAILED DESCRIPTION

[0047] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0048] The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known, or part of the common general knowledge in any country as of the priority date of any of the claims. Throughout this disclosure, various publications, patents, and published patent specifications are referenced by an identifying citation. All documents cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings or sections of such documents herein specifically referred to are incorporated by reference.

[0049] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a step" means one step or more than one step.

[0050] The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements, or method steps. The terms also encompass "consisting of" and "consisting essentially of", which enjoy well-established meanings in patent terminology.

[0051] Whereas the terms "one or more" or "at least one", such as one or more members or at least one member of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members. In another example, "one or more" or "at least one" may refer to 1, 2, 3, 4, 5, 6, 7 or more.

[0052] The terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the disclosure described herein are capable of operation in other sequences than described or illustrated herein.

[0053] As used herein, the term "and / or" when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0054] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" or "in a particular embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while certain embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art.

[0055] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all subranges subsumed therein. This applies to numerical ranges irrespective of whether they are introduced by the expression "from... to..." or the expression "between... and..." or another expression.

[0056] As used herein, the terms "about" or "approximately" are used to provide flexibility to a numerical value or range endpoint by providing that a given value may be "a little above" or "a little below" said value or endpoint, depending on the specific context. Hence, the terms "about" or "approximately" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value or endpoint, such as variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention.

[0057] Unless otherwise stated, use of the terms "about" or "approximately" in accordance with a specific number or numerical range should also be understood to provide support for such numerical terms or range without the term "about". For example, the recitation of "about 30" should be construed as not only providing support for values a little above and a little below 30, but also for the actual numerical value of 30 as well.

[0058] As used herein, the term "substantially" refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is "substantially" enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of "substantially" is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.

[0059] The terms "wt.%," "vol%", or "mol%" refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component.

[0060] Whenever the term "substituted" is used in the present invention, it is meant to indicate that one or more hydrogens on the atom indicated in the expression using "substituted" is replaced with a selection from the indicated group, provided that the indicated atom's normal valency is not exceeded, and that the substitution results in a chemically stable compound. Where groups can be substituted, such groups may be substituted with one or more, preferably one, two or three substituents. Substituents optionally are designated with or without bonds. Regardless of bond indications, if a substituent is polyvalent (based on its position in the structure referred to), then any and all possible orientations of the substituent are intended.

[0061] The term "hydroxyl" or "hydroxy" as used herein refers to the group -OH.

[0062] The term "alkyl" as a group or part of a group, refers to a hydrocarbyl group of formula CnHjn+i wherein n is a number greater than or equal to 1, with no site of unsaturation. Alkyl groups may be linear or branched and may be substituted as indicated herein. Generally, alkyl groups can comprise from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term "Ci.galkyl", as a group or part of a group, refers to a hydrocarbyl group of formula CnHjn+i wherein n is a number ranging from 1 to 6. Thus, for example, "Ci.galkyl" includes all linear or branched alkyl groups with between 1 and 6 carbon atoms, and thus includes methyl, ethyl, n-propyl, / -propyl, butyl, and its isomers (e.g., n-butyl, / -butyl, and t-butyl); pentyl and its isomers, hexyl, and its isomers, etc. For example, Ci.4alkyl includes all linear or branched alkyl groups having 1 to 4 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, / -propyl, 2-methyl-ethyl, butyl, and its isomers (e.g., n-butyl, / -butyl, and t-butyl), and the like. In particular embodiments, the term alkyl refers to Ci i2alkyl (Ci-i2 hydrocarbons), yet more in particular to Cuoalkyl (Cno hydrocarbons), yet more in particular to Ci.gal kyl (Ci-9 hydrocarbons), yet more in particular to Ci.galkyl (Ci.g hydrocarbons) as further defined herein above. Non-limiting examples of alkyl include methyl, ethyl, 1-propyl (n-propyl), 2-propyl ( / Pr), 1-butyl, 2-methyl-l-propyl(i-Bu), 2-butyl (s-Bu), 2-dimethyl-2-propyl (t-Bu), 1-pentyl (n-pentyl), 2- pentyl, 3-pentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 3-methyl-l-butyl, 2-methyl-l-butyl, 1-hexyl, 2- hexyl, 3-hexyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl- 3-pentyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n- dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-icosyl.

[0063] The term "alkenyl" as a group or part of a group, refers to an unsaturated hydrocarbyl group which may be linear, or branched, comprising one or more with at least one site (usually 1 to 3, preferably 1) of unsaturation, namely at least one sp2carbon-sp2carbon double bond. Generally, alkenyl groups can comprise from 2 to 12 carbon atoms, preferably from 2 to 10 carbon atoms, preferably from 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. Examples of Cj.galkenyl groups are ethenyl, 2-propenyl, 2-butenyl, 3-butenyl, 2-pentenyl and its isomers, 2-hexenyl and its isomers, 2,4-pentadienyl, and the like. The double bond may be in the cis or trans configuration.

[0064] The term "cycloalkyl", as a group or part of a group, refers to a cyclic alkyl group, that is a monovalent, saturated, hydrocarbyl group having 1 or more cyclic structure, and comprising from 3 to 20 carbon atoms, more preferably from 3 to 10 carbon atoms, more preferably from 3 to 8 carbon atoms; more preferably from 3 to 6 carbon atoms. Cycloalkyl includes all saturated hydrocarbon groups containing one or more rings, including monocyclic, bicyclic groups or tricyclic. For example, cycloalkyl comprises a C3-10 monocyclic or C7-18 polycyclic saturated hydrocarbon, such as for instance cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylethylene, methylcyclopropylene, cyclohexyl, cycloheptyl, cyclooctyl, cyclooctylmethylene, norbornyl, fenchyl, trimethyltricycloheptyl, decalinyl, adamantyl and the like. The further rings of multi-ring cycloalkyls may be either fused, bridged and / or joined through one or more spiro atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term "C3- locycloalkyl", refers to a cyclic alkyl group comprising from 3 to 10 carbon atoms. For example, the term "Cs-gcycloalkyl", refers to a cyclic alkyl group comprising from 3 to 8 carbon atoms. For example, the term "Cs-ecycloalkyl", refers to a cyclic alkyl group comprising from 3 to 6 carbon atoms. For the avoidance of doubt, fused systems of a cycloalkyl ring with a heterocyclic ring are considered as heterocycle irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkyl ring with an aryl ring are considered as aryl irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkyl ring with a heteroaryl ring are considered as heteroaryl irrespective of the ring that is bound to the core structure.

[0065] The term "aryl", as a group or part of a group, refers to a polyunsaturated, aromatic hydrocarbyl group having a single ring (i.e. phenyl) or multiple aromatic rings fused together (e.g. naphthyl), or linked covalently, typically comprising 6 to 12 carbon atoms; wherein at least one ring is aromatic, preferably comprising 6 to 10 carbon atoms, wherein at least one ring is aromatic. The aromatic ring may optionally include one to two additional rings (either cycloalkyl, heterocyclyl or heteroaryl) fused thereto. Examples of suitable aryl include Cg-uaryl, preferably Cg-ioaryl, more preferably Cg-garyl. Nonlimiting examples of aryl comprise phenyl, biphenylyl, biphenylenyl, or 1-or 2-naphthanelyl; 5- or 6- tetralinyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-azulenyl, 4-, 5-, 6 or 7-indenyl, 4- or 5-indanyl, 5-, 6-, 7- or 8- tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, and 1,4-dihydronaphthyl; 1-, 2-, 3-, 4- or 5-pyrenyl. A "substituted aryl" refers to an aryl group having one or more substituent(s) (for example 1, 2 or 3 substituent(s), or 1 to 2 substituent(s)), at any available point of attachment.

[0066] The term "arylalkyl", as a group or part of a group, means a alkyl as defined herein, wherein at least one hydrogen atom is replaced by at least one aryl as defined herein. Non-limiting examples of arylalkyl group include benzyl, phenethyl, dibenzylmethyl, methylphenylmethyl, 3-(2-naphthyl)-butyl, and the like.

[0067] The term "immiscible" as used herein generally refers to a property of two or more substances, compounds, or compositions (typically liquids) that are incapable of mixing or blending together to form a homogeneous solution, typically at ambient conditions. When combined, immiscible substances form distinct separate phases (e.g., phase-separated liquids), maintaining their individual identities and not dissolving into each other.

[0068] The term "ambient conditions" as used herein refers to conditions of temperature, pressure, and humidity present in natural or typical indoor environment. In particular, the temperature typically ranges from about 20 °C to about 25 °C, which is considered standard room temperature. The pressure is approximately 101.3 kPa and relative humidity levels range from about 30% to 70%.

[0069] In the following passages, different aspects or embodiments of the invention are defined in more detail. Each aspect or embodiment so defined may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. In the present description, technology is described by means of which a polyurethane (PU) material can be depolymerized to produce valuable monomers that can be recovered with good purity and efficiency. More specifically, the present depolymerization process is characterized by the formation of at least three phase-separated liquids, which allows to separate higher quality polyols and amine(s) obtained from the depolymerized PU material. Advantageously, the present process minimizes the need for expensive and energy-intensive purification methods when chemically recycling a PU material.

[0070] Another advantage of the present depolymerization process is that cross-contamination between the at least three phase-separated liquids can be minimized, therefore decreasing the need for additional purification steps.

[0071] Another advantage of the enhanced separation capability of the present process is that it can allow for the recycling of a wider variety of PU materials, including those with complex formulations and / or containing additives and fillers.

[0072] Yet another advantage of the present process is that the monomers or oligomers recovered from the present PU material depolymerization process can be used to develop new types of polymers or other materials with desirable properties.

[0073] Accordingly, one aspect of the present invention relates to a process for the depolymerization of a polyurethane material, derived from at least two immiscible polyols, the process comprising the steps of: a) contacting the polyurethane material with a depolymerization agent comprising an amine and / or alkanolamine to obtain a depolymerization mixture; b) heating the depolymerization mixture to a temperature of from 80.0 to 250.0 °C, such as from 150.0 to 250.0 °C; c) allowing the formation of at least three phase-separated liquids, such as three, four, five, six, seven, or eight phase-separated liquids; and d) separating the at least three phase-separated liquids; wherein the at least three phase-separated liquids comprise a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds. In other words, the present invention encompasses a process for the recovery of monomers, oligomers, or other lower molecular weight compounds produced during the depolymerization of a defined polyurethane (PU) material.

[0074] (Preferred) embodiments of the present process relating to the nature of the PU material, the steps of the process and the components that can be recovered are described below in greater detail.

[0075] Polyurethane (PU) in the context of the present invention is generally understood to refer to a class of polymers primarily composed of organic units joined by carbamate links. The term "polyurethane (PU) material" as used herein refers to material comprising one or more polyurethanes. For instance, the PU material may be a blend or physical admixture of one or more polyurethanes.

[0076] In the context of the present invention, the PU material is derived from two or more different polyols. Typically, in the context of the present invention, the PU material is made from one or more first polyols and one or more second polyols, which are immiscible.

[0077] More in particular, the PU material is the polymer product of contacting one or more isocyanate compounds and two or more immiscible polyols, optionally in the presence of a catalyst and one or more additives or fillers. Exemplary isocyanate compounds in this context are organic (poly)isocyanates such as diisocyanates and polyfunctional isocyanates, preferably aromatic polyfunctional isocyanates. Individual examples that can be mentioned are tolylene 2,4 and 2,6- diisocyanate (TDI) and the corresponding isomer mixtures, diphenylmethane 4,4' , 2,4' and 2,2' diisocyanate (MDI) and the corresponding isomer mixtures, mixtures composed of diphenylmethane 4,4'- and 2,4'- diisocyanates, polyphenyl polymethylene polyisocyanates, mixtures composed of diphenylmethane 4,4'-, 2,4'- and 2,2'- diisocyanates and of polyphenyl polymethylene polyisocyanates (crude MDI) and mixtures composed of crude MDI and of tolylene diisocyanates. The organic diisocyanates and polyfunctional isocyanates may be used individually or in the form of mixtures. The contacting of the aforementioned compounds may have involved heating of a mixture thereof as is apparent to the person skilled in the art

[0078] As used herein, the term "immiscible polyols" has a well-known meaning within the art and is used herein as such. More specifically, it refers to two or more polyols or polyol components which, when combined under standard mixing conditions (e.g., at 20-25 °C and atmospheric pressure) form a heterogeneous mixture characterized by phase separation. Preferably, phase separation occurs macroscopically (visible separation), within a given timeframe (e.g., within 1 hour of mixing).

[0079] In some preferred embodiments, the at least three phase-separated liquids comprise a first liquid comprising at least 75 wt.%, or at least 80.0 wt.%, of one or more first polyols; a second liquid comprising at least 75 wt.%, or at least 80.0 wt.%, of one or more second polyols, and a third liquid comprising at least 75 wt.%, or at least 80.0 wt.%, of depolymerization agent; with wt.% based on the total weight of each layer. The third liquid may further comprise one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds.

[0080] The two or more immiscible polyols that were used in the formulation of the PU material typically result in distinct, phase-separated domains in the PU polymer matrix. The PU material used in the process of the present invention can therefore exhibit a micro-phase separated morphology, where domains rich in a first polyol are dispersed within a continuous matrix of a second polyol, or vice versa. The degree of separation between the polymer phases and domain sizes may depend on the nature of the two or more polyols, their molecular weight, weight ratio, and reaction conditions used for preparing the PU material.

[0081] Several analytical techniques well-known to the skilled practitioner may be used to determine whether the PU material comprises phase-separated domains. For instance, differential scanning calorimetry (DSC) measurements may be performed which measure the thermal transitions (e.g., glass transitions temperature (Tg)) of the polymer. It is well-known that multiple Tg values can indicate the presence of distinct microphases corresponding to different immiscible polyol components. Alternatively, dynamic mechanical analysis (DMA) can be used to determine the mechanical properties of the polymer as a function of temperature. The presence of multiple storage modulus peaks or loss modulus peaks at different temperatures typically suggest micro-phase separation. Another method for determining the presence of phase-separated domains is transmission electron microscopy (TEM), wherein high-resolution images of the polymer's internal structure are made. From said images, distinct regions of varying electron density, corresponding to different polyol domains, can be observed.

[0082] The process of the present invention is of particular interest for the recycling of PU materials which are the product of one or more isocyanate compounds reacted with at least two immiscible polyols, such as two, three, four, five, six, seven, or eight immiscible polyols.

[0083] The PU material used in the present process may be in solid, microcellular, or foam form and is preferably a rubbery, elastomeric, flexible material.

[0084] In particular embodiments, the PU material is PU scrap or foam. In particular embodiments, the PU material is foam obtained from car seats, sofas, matrasses, dashboards, door panels, neck braces, knee supports, insoles, padding in shoes, helmets or gloves, acoustic panels, sealings of doors and windows, padding clothing and other and other cushioning material. This has the advantage that the present process may facilitate closed-loop recycling, wherein waste materials can be recycled without significant loss of quality. This aligns with the principles of circular economy, promoting resource efficiency.

[0085] During the process of the present invention, the urethane bonds (i.e., the adduct of an isocyanate group and an alcohol group) present in the PU material are depolymerized or cleaved, resulting in the recovery of its original monomers and other smaller molecules. More specifically, the present process is characterized in that it involves the separation of the depolymerized PU material into different phases, which allows the recuperation of original polyols used to prepare the PU material and other molecules, such as amine compounds and optionally carbamate compounds and / or urea compounds, as will be further detailed herein.

[0086] In a first step of the present process (step a) as referred to herein), the PU material is contacted with a depolymerization agent comprising an amine and / or alkanolamine to obtain a depolymerization mixture. Preferably, the step of contacting the PU material with the depolymerization agent comprises mixing both components to facilitate the depolymerization reaction.

[0087] In particular embodiments, the PU material may be subjected to a physical degradation step before or during depolymerization. For instance, to facilitate contacting of the PU material and the depolymerization agent, it can be desirable to chop, pulverize, grind, or otherwise comminute the PU material such that it is in the form of relatively small particles or granules. If the PU material is a foam, it may be partially or fully compressed prior to mixing. If the PU material is in solid form, an initial pulverization step is highly advantageous so as to maximize the surface area available for reaction (thereby reducing the reaction time required to achieve the desired level of depolymerization).

[0088] The term "depolymerization agent" as used herein generally refers to a compound or a mixture of compounds that can break down the polymeric PU material into its constituting monomers, oligomers, or other lower molecular weight compounds. In particular, the depolymerization agent may interact with the polymer chains, cleaving the chemical bonds that link the repeating units (i.e., urethane bonds), thereby effectively reversing the original polymerization process for manufacturing the PU material.

[0089] In the context of the present invention, the depolymerization agent used preferably has a low affinity for the polyol comprised in the PU material. The tendency of the depolymerization agent and constituting polyols to spontaneously phase-separate at ambient conditions may be determined experimentally by mixing the depolymerization agent and the at least two immiscible polyols used to prepare the PU material. Alternatively, this may be determined theoretically by modelling experiments using group contribution methods or coarse-grained molecular dynamics.

[0090] In particular embodiments, the depolymerization agent is immiscible with one or more polyol, and preferably each polyol, comprised in the PU material.

[0091] In particular embodiments, the depolymerization agent comprises an amine and / or alkanolamine having a boiling point equal to or greater than 150 °C. The relatively high boiling point of the amine and / or alkanolamine has the advantage that the present process can minimize evaporation losses during depolymerization of the PU material. Additionally, this allows for better control of the reaction environment by maintaining uniform mixing, consistent contact between reactants (i.e., the PU material and depolymerization agent), and stable reaction conditions.

[0092] In particular embodiments, the depolymerization agent comprises an amine. In particular embodiments, the depolymerization agent comprises an amine comprising at least one primary amino functional group (-NH2) and / or at least one secondary amino functional group (-NHRa, wherein Rais an alkyl, alkenyl, or cycloalkyl as defined herein, preferably wherein Rais an alkyl). Preferably, the amine does not comprise an hydroxyl functional group (-OH).

[0093] In particular embodiments, the depolymerization agent comprises an amine comprising from 2 to 12 carbon atoms, at least one primary amino functional group (-NH2) and / or at least one secondary amino functional group (-NHRa, wherein Rais an alkyl, alkenyl, or cycloalkyl as defined herein, preferably wherein Rais an alkyl).

[0094] In particular embodiments, the depolymerization agent comprises an amine selected from the group consisting of pentane-l,5-diamine, (dibutyl)amine, dodecylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and mixtures thereof.

[0095] In particular embodiments, the depolymerization agent comprises a linear polymeric amine having the following repeating unit -[CH2CH2NH]- and terminated on each end with a primary amino functional groups, such as diethylenetriamine, triethylenetetramine, or tetraethylenepentamine.

[0096] In particular embodiments, the depolymerization agent comprises an alkanolamine. The term "alkanolamine" as used herein generally refers to a chemical compound that comprises both an hydroxy group (-OH) and an amino group (-NH2, -NHR, or -NR2) within the same molecule. These compounds are characterized by having at least one hydroxyalkyl group attached to a nitrogen atom.

[0097] In particular embodiments, the depolymerization agent comprises an alkanolamine comprising at least one hydroxyl functional group (-OH) and at least one primary amino functional group and / or secondary amino functional group and / or tertiary amino group. Preferably, the depolymerization agent comprises an alkanolamine comprising at least one hydroxyl functional group (-OH) and at least one primary amino functional group and / or secondary amino functional group.

[0098] In particular embodiments, the depolymerization agent comprises an alkanolamine comprising from 2 to 8 carbon atoms, at least one hydroxyl functional group (-OH) and at least one primary amino functional group and / or secondary amino functional group and / or tertiary amino group. Preferably, the depolymerization agent comprises an alkanolamine comprising from 2 to 8 carbon atoms, at least one hydroxyl functional group (-OH) and at least one primary amino functional group and / or secondary amino functional group.

[0099] In particular embodiments, the depolymerization agent comprises an alkanolamine comprising from 2 to 8 carbon atoms, at least two hydroxyl functional groups (-OH) and at least one secondary amino functional group or tertiary amino group.

[0100] In particular embodiments, the depolymerization agent comprises an alkanolamine comprising from 2 to 8 carbon atoms, at least two hydroxyl functional groups (-OH) and at least one primary amino functional group or secondary amino group.

[0101] In particular embodiments, the depolymerization agent comprises an alkanolamine according to the following structural Formula (I) wherein,

[0102] R1and R2are each independently selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl, and alkylaryl; and X is selected from the group consisting of hydrogen, alkyl, alkenyl, and cycloalkyl.

[0103] In particular embodiments, the depolymerization agent comprises an alkanolamine according to the following structural Formula (la) wherein,

[0104] R1and R2are each independently selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl, and alkylaryl; and X1is hydrogen.

[0105] In particular embodiments, the depolymerization agent comprises an alkanolamine according to the following structural Formula (II)

[0106] CD wherein,

[0107] R3is selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl, arylalkyl; and X2, X3are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, and cycloalkyl; with the provision that at least one of X2, X3is hydrogen.

[0108] In particular embodiments, the depolymerization agent comprises an alkanolamine according to the following structural Formula (I) wherein,

[0109] R1and R2are each independently selected from the group consisting of alkyl, cycloalkyl, and aryl; and X is selected from the group consisting of hydrogen and alkyl.

[0110] In particular embodiments, the depolymerization agent comprises an alkanolamine according to the following structural Formula (I) wherein,

[0111] R1and R2are each independently selected from the group consisting of Cj-galkyl, Cg-gcycloalkyl, and Cg. ioaryl; and X is selected from the group consisting of hydrogen and Ci-galkyl.

[0112] In particular embodiments, the depolymerization agent comprises an alkanolamine according to the following structural Formula (la) wherein,

[0113] R1and R2are each independently selected from the group consisting of Cz-gal kyl, Cg-gcycloalkyl, and Cg. ioaryl; and X1is hydrogen.

[0114] In particular embodiments, the depolymerization agent comprises an alkanolamine selected from the group consisting of diethanolamine, monoethanolamine, diisopropanolamine, N-(2- hydroxypropyl)ethanolamine, N-benzylethanolamine, N-benzyl-N-(2-hydroxypropyl)ethanolamine, dipropanolamine, 3,3' iminobis(2 -hydroxybutane), N-(2-hydroxypropyl)ethylenediamine, 2- (diisopropylamino)ethanol, diglycolamine, N-methyl diethanolamine, 2-amino-2-methyl-l-propanol, 2-piperidine ethanol, l,3-diamino-2-propanol, 2-(methylamino)ethanol, 2-amino-l,3-propanediol, 3- amino-l-propanol, 4-amino-l-butanol, 5-amino-l-pentanol, 6-amino-l-hexanol, and mixtures thereof.

[0115] Preferably, the depolymerization agent comprises an alkanolamine selected from the group consisting of diethanolamine, monoethanolamine, N-(2-hydroxypropyl)ethanolamine, N-benzylethanolamine, N-benzyl-N-(2-hydroxypropyl)ethanolamine, dipropanolamine, N-(2-hydroxypropyl)ethylenediamine, 2-(diisopropylamino)ethanol, diglycolamine, N-methyl diethanolamine, 2-amino-2-methyl-l- propanol, 2-piperidine ethanol, l,3-diamino-2-propanol, 2-(methylamino)ethanol, 2-amino-l,3- propanediol, 3-amino-l-propanol, 4-amino-l-butanol, 5-amino-l-pentanol, and mixtures thereof.

[0116] More preferably, the depolymerization agent comprises an alkanolamine selected from the group consisting of diethanolamine, monoethanolamine, N-(2-hydroxypropyl)ethanolamine, N- benzylethanolamine, dipropanolamine, N-(2-hydroxypropyl)ethylenediamine, diglycolamine, 2- amino-2-methyl-l-propanol, 2-piperidine ethanol, l,3-diamino-2-propanol, 2-(methylamino)ethanol, 2-amino-l,3-propanediol, 3-amino-l-propanol, 4-amino-l-butanol, 5-amino-l-pentanol, and mixtures thereof.

[0117] In particular embodiments, the polyurethane material and depolymerization agent comprising an amine and / or alkanolamine are contacted in a weight ratio of from 1.0:1.1 to 1.0:5.0, or from 1.0:1.2 to 1.0:5.0, or from 1.0:1.3 to 1.0:5.0, or from 1.0:1.4 to 1.0:5.0, or from 1.0:1.5 to 1.0:5.0, or from 1.0:1.5 to 1.0:4.5, or from 1.0:1.5 to 1.0:4.0 to obtain the depolymerization mixture. In particular embodiments, the weight ratio is 1:1.5-1:2.0.

[0118] Advantageously, it has been found that the above listed compositions of the depolymerization agent and / or weight ratios with respect to the PU material may provide a good yield of one or more amine compounds, instead of the complex mixtures of carbamates and amines reported in the art.

[0119] In particular embodiments, the depolymerization agent may further comprise an accelerator, such as about 0.1 to 1.0 wt.% of an accelerator; with wt.% relative to the total weight of the depolymerization agent. Non-limiting examples of suitable accelerators include water or an inorganic base, such as potassium hydroxide, sodium hydroxide, or lithium hydroxide. The accelerator may increase the rate of degradation. This may advantageously lower the temperature and / or time needed to depolymerize the PU material.

[0120] In the present process the PU material and depolymerization agent may be contacted in any suitable reaction vessel. Non-limiting examples include a container, such as a flask or reactor, where the PU material and depolymerization agent can be mixed and reacted to form a depolymerization mixture. A mechanical or magnetic stirrer may be used to ensure continuous mixing of the depolymerization mixture. The PU material may be provided to the reaction vessel by suitable conveying means, such as a automated dosing systems. The depolymerization agent may be provided to the reaction vessel by a suitable feeding apparatus, such as pumps or funnels.

[0121] According to the present invention, the depolymerization mixture obtained by contacting the PU materials and the depolymerization agent comprising an amine and / or alkanolamine is subjected to a heating step at a temperature of from 80.0 to 250.0 °C to advantageously accelerate the depolymerization reaction.

[0122] In particular embodiments, the heating step is performed at a temperature of from 100.0 to 250.0 °C, or from 110.0 to 250.0 °C, or from 120.0 to 250.0 °C, or from 130.0 to 250.0 °C, or from 140.0 to 250.0 °C, or from 150.0 to 250.0 °C. A temperature control system may be used to monitor and maintain the desired temperature, as is apparent to the person skilled in the art. In particular embodiments, the heating step is performed at a temperature of from 160.0 to 250.0 °C, or from 170.0 to 250.0 °C, or from 180.0 to 250.0 °C, or from 190.0 to 250.0 °C, or from 200.0 to 250.0 °C.

[0123] In particular embodiments, the heating step is carried out for a period of from 5 minutes to 24 hours, or from 5 minutes to 22 hours, or from 5 minutes to 20 hours, or from 5 minutes to 18 hours, or from 5 minutes to 16 hours, or from 5 minutes to 14 hours, or from 5 minutes to 12 hours, or from 5 minutes to 10 hours, or from 5 minutes to 8 hours, or from 10 minutes to 8 hours, or from 15 minutes to 8 hours, or from 15 minutes to 6 hours.

[0124] In particular embodiments, the heating step is performed at a temperature of from 150.0 to 250.0 °C for a period of from 5 minutes to 24 hours, or at a temperature of from 200.0 to 250.0 °C for a period of from 5 minutes to 6 hours.

[0125] In exemplary embodiments, the present process is directed to the depolymerization of a polyurethane material made from at least two immiscible polyols, the process comprising the steps of: a) contacting the polyurethane material with a depolymerization agent comprising an alkanolamine according to structural Formula (la) or (II) as defined herein in a weight ratio of from 1.0:1.5 to 1.0:4.0, preferably 1.0:2.0, to obtain a depolymerization mixture; b) heating the depolymerization mixture to a temperature of from 150.0 to 250.0 °C, preferably 200.0 to 250.0°C, for a period of from 5 minutes to 24 hours, preferably 15 minutes to 6 hours; c) allowing the formation of at least three phase-separated liquids; and d) separating the at least three phase-separated liquids; wherein the at least three phase-separated liquids comprise a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds; and wherein the depolymerization agent is immiscible with each polyol.

[0126] Advantageously, experimentation has revealed that the yield of the one or more amine compounds may be tuned with temperature and / or the time period of heating.

[0127] In particular embodiments, the heating step b) is carried out in an inert environment, preferably comprising nitrogen, argon, helium, and / or dry air. This has the advantage that possible oxidation and thermal degradation of the PU material and / or produced chemicals may be avoided. Importantly, the process for depolymerizing PU material as described herein allows the formation of at least three phase-separated liquids such as three, four, five, six, seven, or eight phase-separated liquids, which may advantageously improve separation of the polyols and amine compounds generated during depolymerization of the PU material. In particular, once the depolymerization reaction is complete, the depolymerization mixture is allowed to settle and cool. Alternatively, the depolymerization mixture may be cooled to ambient temperature (from about 20 °C to about 25 °C).

[0128] The term "phase-separated liquid" as used herein refers to a part of a liquid mixture that has undergone separation into distinct regions, layers, or phases, each with different compositions and properties. The resulting regions, layers, or phases coexist but do not mix homogeneously.

[0129] In particular embodiments, step c) of the present process comprises cooling or allowing to cool, preferably cooling or allowing to cool to 20 °C. This has the advantage that separation of the liquid phases may be improved.

[0130] In particular embodiments, the phases are generated as adjacent horizontal layers in the reaction vessel in which the depolymerization has been carried out. In particular embodiments, an upper, middle and lower layer is formed in the liquid, each representing a different phase. Preferably, the upper layer primarily comprises one or more first polyols, the middle layer primarily comprises one or more second polyols and the bottom layer primarily comprises the depolymerization agent and one or more amine compounds. However, in particular embodiments the first and middle layer may also comprise amines and other reaction products (such as carbamate or urea compounds, MDA and diethanolamine).

[0131] Alternatively, the (hot) depolymerization mixture may be transferred to a settling device, optionally a cooled settling device, wherein the depolymerization mixture spontaneously phase-separates in at least three distinct layers.

[0132] The process of the present invention further provides for the separation of the at least three phase- separated liquids formed. Non-limiting suitable methods for separating the at least three phase- separated liquids include decantation, centrifugation, liquid-liquid extraction, mechanical separation using a separatory funnel, chromatography, and distillation. Preferably, the at least three phase- separated liquids are separated by means of decantation, centrifugation, liquid-liquid extraction, and mechanical separation using a separatory funnel.

[0133] From the separated phases, the one or more first polyols, the one or more second polyols, and the one or more amine compounds may be recovered to obtain recycled first polyols, second polyols, and amine compounds that can advantageously be used as fresh raw materials for PU production. A particular advantage of the formation of at least three phase-separated liquids in the present process is that the isolation of polyols from the liquids requires less energy as they are already separated based on affinity and partitioning between the separate phases.

[0134] It will be understood that the one or more first polyols and one or more second polyols that can be obtained by the methods of the present invention will correspond to the immiscible polyols used in the manufacture of the original PU material.

[0135] The presence of at least two different polyols in the PU material to which the method is applied allows the formation of three phase-separated liquids. Preferably the three phase-separated liquids comprise a first liquid comprising the one or more first polyols, a second liquid comprising the one or more second polyols; and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds. In particular embodiments as detailed above, the first and second liquid also contain other components such as carbamate or urea compounds, MDA, and diethanolamine. Particularly, these can also be present in the second layer, whereby the third layer comprises remaining aromatic compounds and diethanolamine.

[0136] In particular embodiments of the methods of the invention, when the PU material used is derived from a first polyol and two second polyols, will ensure the formation of three phase-separated liquids, wherein the three phase-separated liquids comprise a first liquid comprising the first polyol, a second liquid comprising the two second polyols, and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds.

[0137] In particular embodiments of the process of the invention, when the PU material is derived from two or more first polyols, and two or more second polyols, will ensure the formation of three phase- separated liquids wherein the three phase-separated liquids comprise a first liquid comprising the two or more first polyols, a second liquid comprising the two or more second polyols, and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds.

[0138] In particular embodiments of the process of the invention, when the PU material is derived from one or more first polyols, one or more second polyols and one or more further polyols, the process as disclosed allows for the formation of more than three phase-separated liquids, the number corresponding to the different types of immiscible polyols, wherein the different phase-separated liquids each comprise different polyols and preferably a separate liquid comprises the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds. It can be envisaged that in some embodiments, one or more types of polyols may also be present in the same layer as the depolymerization agent.

[0139] In particular embodiments, the one or more first polyols and / or second or further polyols may have an hydroxyl (OH) value of from 10 to 1200 mg KOH / g, or from 10 to 1000 mg KOH / g, or from 10 to 900 mg KOH / g, or from 10 to 800 mg KOH / g, or from 10 to 500 mg KOH / g, or from 20 to 500 mg KOH / g. The OH value can be determined, in particular, in accordance with the DIN standard DIN 53240:1971-12.

[0140] In particular embodiments, the one or more first polyols and the one or more second or further polyols may have a different hydroxyl (OH) value. Preferably, the difference in OH value is of at least 10 mg KOH / g.

[0141] In particular embodiments, the first polyols have a hydroxyl (OH) value of 30-40 mg KOH / g and the second polyols have an OH value of 45-60 mg KOH / g.

[0142] In particular embodiments, the one or more first polyols and / or one or more second or further polyols may have a functionality of from 1.5 to 8.0, or from 1.5 to 6.0, or from 1.5 to 5.0, or from 1.5 to 4.0 or from 1.5 to 3.0.

[0143] In particular embodiments, the one or more first polyols and / or one or more second or further polyols may have a number average molecular weight (Mn) of from 1500 to 20000 g / mol, or from 1500 to 17500 g / mol, or from 1500 to 15000 g / mol, or from 1500 to 12500 g / mol, or from 1500 to 10000 g / mol, or from 1750 to lOOOOg / mol, or from 2000 to 10000 g / mol, or from 2000 to 9000 g / mol, or from 2000 to 8000 g / mol, or from 2000 to 7000 g / mol; as determined by Gel Permeation Chromatography (GPC), especially using polypropylene glycol (PPG) as reference standard and tetrahydrofuran (THF) as eluent.

[0144] In particular embodiments, the one or more first polyols and the one or more second or further polyols may have a different number average molecular weight (Mn). Preferably, the difference in number average molecular weight (Mn) between the one or more first polyols and the one or more second polyols is at least 250 g / mol, or at least 500 g / mol, or at least 750 g / mol, or at least 1000 g / mol.

[0145] In particular embodiments, the one or more first polyols have a number average molecular weight (Mn) between 3000 g / mol and 5000 g / mol and the one or more second polyol have an Mn between 2000 g / mol and 4000 g / mol. In particular embodiments, the one or more first polyols and the one or more second or further polyols may have substantially the same functionality and hydroxyl value, but a different number average molecular weight (Mn).

[0146] In particular embodiments, the first polyol is a copolymer of ethylene oxide and propylene oxide and the second polyol is a polypropylene glycol. In alternative embodiments, both the first and the second polyol are copolymers of ethylene oxide and propylene oxide, but with different OH values.

[0147] In particular embodiments, the first polyol is a copolymer of ethylene oxide and propylene oxide having a number average molecular weight (Mn) between 3000g / mol and 5000g / mol and an hydroxyl (OH) value of 36 mg KOH / g and the second polyol was a polypropylene glycol having an Mn between 2000 g / mol and 3000 g / mol and an OH value of 58 mg KOH / g.

[0148] In particular embodiments, the one or more first polyols and one or more second or further polyols are different polyether polyols or acrylic polyols. Preferably, each polyether polyol or acrylic polyol comprises active hydrogens. Preferably, the one or more first polyols and one or more second polyols are different polyether polyols.

[0149] In preferred embodiments, the one or more first polyols and one or more second or further polyols are not polyester polyols. It has been found herein that polyester polyols can partially degrade under the depolymerization conditions as described herein, which may be disadvantageous for further purification of the phase-separated liquids.

[0150] Polyether polyols that may be obtained from the present depolymerization process include oligoether or polyether compounds having primary and / or secondary end groups, preferably hydroxyl groups. In particular embodiments, a polyether polyol as described herein may comprise amino groups. Nonlimiting examples are "Jeffamine" polyoxypropylamines sold by Texaco Chemical Co. Polyether polyols are generally made by the catalytic ring-opening polymerization of one or more cyclic ethers such as epoxides, oxetanes, or oxolanes. Initiators having two or more active hydrogens such as polyhydric alcohols, amines, or acids may be employed to vary the functionality (number of active hydrogens) of the polyether. If more than one type of cyclic ether is used, they may be reacted either simultaneously (to yield a random-type copolymer) or sequentially (to yield a block-type copolymer). Non-limiting examples of cyclic ethers include propylene oxide, ethylene oxide, butylene oxide, tetrahydrofuran, and oxetane.

[0151] In particular embodiments, the polyols recovered from the depolymerized PU material are polyether polyols selected from the group consisting of polypropylene glycol, polyethylene glycol, 1 polytetramethylene glycol, polytrimethylene glycol, ethylene oxide-capped polypropylene glycol, random copolymers of ethylene oxide and propylene oxide, and combinations thereof.

[0152] In preferred embodiments, the one or more first polyols and one or more second or further polyols are polyether polyols having a different ethylene oxide-based content (-[OCH2CH2]-) and / or propylene oxide-based content (-[OCH(CH3)CH2]-)).

[0153] In preferred embodiments, the one or more first polyols and one or more second or further polyols are polyether polyols having a different ethylene oxide-based content (-[OCH2CH2]-) and / or propylene oxide-based content (-[OCH(CH3)CH2]-)) and have a difference in number average molecular weight (Mn) of at least 250 g / mol.

[0154] In preferred embodiments, the one or more first polyols may have a propylene oxide-based content (-[OCH(CH3)CH2]-) higher than the one or more second polyols.

[0155] In preferred embodiments, the one or more second polyols may have an ethylene oxide-based content (-[OCH2CH2]-) higher than the one or more first polyols.

[0156] In certain embodiments, the one or more first polyols comprise -[OCH(CH3)CH2]- as the main repeating unit and the one or more second polyols comprise -[OCH(CH3)CH2]- and -[OCH2CH2]- as the main repeating units.

[0157] In certain embodiments, the one or more first polyols are polypropylene glycols and the one or more second polyols are random copolymers of ethylene oxide and propylene oxide.

[0158] In certain embodiments, the one or more first polyols are random copolymers of ethylene oxide and propylene oxide and the one or more second polyols are polyethylene glycols.

[0159] In certain embodiments, the one or more first polyols are random copolymers of ethylene oxide and propylene oxide and the one or more second polyols are random copolymers of ethylene oxide and propylene oxide; wherein the one or more second polyols have an ethylene oxide-based content (- [OCH2CH2]-) higher than the one or more first polyols.

[0160] Acrylic polyols that may be obtained from the present depolymerization process include oligomers or polymers made by addition polymerization of different unsaturated polymerizable materials, at least one of which is a hydroxy-containing ethylenically unsaturated polymerizable material. Examples of such materials, which are suitable for use in preparing the acrylic polyol are vinyl monomers, such as hydroxyalkyl acrylates and methacrylates, including the acrylic acid and methacrylic acid esters of ethylene glycol and propylene glycol. These acrylates and methacrylates often comprise C2-6 alkyl groups. Specific examples include methyl methacrylate and n-butyl methacrylate. Other suitable materials include lauryl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate. A vinyl monomer that is often included is styrene. Also suitable are hydroxycontaining esters and / or amides of unsaturated acids such as maleic acid, fumaric acid, itaconic acid and the like.

[0161] The process of the present invention further allows to recuperate one or more amine compounds. It should be noted that the one or more amine compounds are derivatives of the one or more isocyanate compounds used to originally prepare the PU material, wherein the isocyanate functional group (- NCO) is substituted with a primary amino group (-NH2).

[0162] In particular embodiments, the one or more amine compounds are selected from the group consisting of 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6- hexamethylenediamine, isophorone diamine, 2,3-diaminotoluene, 2,4-diaminotoluene, 3,4- diaminotoluene, 2,6-diaminotoluene, 4,4'-methylenedianiline, 2, 4' -methylenedianiline, 2,2'- methylenedianiline, oligomeric derivatives thereof and / or mixtures thereof. It should be understood that oligomeric derivatives as referred to herein may refer to one or more amine compounds (still) linked to one another by covalent bonds, such as carbamate bonds.

[0163] In preferred embodiments, the one or more amine compounds are selected from the group consisting of 2,3-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 2,6-diaminotoluene, 4,4'- methylenedianiline, 2,4'-methylenedianiline, 2,2'-methylenedianiline, oligomeric derivatives thereof and / or mixtures thereof.

[0164] The optional one or more carbamate compounds and / or urea compounds as referred to herein are depolymerization products, other than polyols and amine compounds, of the present process which may have a variable composition depending on the starting material and / or depolymerization conditions.

[0165] In particular embodiments, in the event that the depolymerization agent comprises diethanolamine, the optional one or more carbamate compounds comprised in the third liquid as described herein may have one or more of the following chemical structures

[0166] In an exemplary embodiment, the depolymerization reaction will result in three phases wherein the first liquid comprises one or more first polyols comprising -[OCHfCHajCHz]- as the main repeating unit; the second liquid comprises one or more second polyols comprising -[OCHfCHajCHz]- and -[OCH2CH2]- as the main repeating units; and the third liquid comprises the depolymerization agent and methylene diphenylamine (MDA) or toluene diamine (TDA) as the main components, depending on whether the PU material used is MDI- or TDI-based.

[0167] In an exemplary embodiment, the first liquid comprises polypropylene glycol (PPG) as the main component; the second liquid comprises polyethylene glycol (PEG) as the main component; and the third liquid comprises the depolymerization agent, comprising an amine and / or alkanolamine, and methylene diphenylamine (MDA) as the main components. In an exemplary embodiment, the first liquid comprises polypropylene glycol (PPG) as the main component; the second liquid comprises polyethylene glycol (PEG) as the main component; and the third liquid comprises the depolymerization agent, comprising an amine, and toluene diamine (TDA) as the main components.

[0168] In an exemplary embodiment, the first liquid comprises polypropylene glycol (PPG) as the main component; the second liquid comprises a random copolymer of ethylene oxide and propylene oxide as the main component; and the third liquid comprises the depolymerization agent, comprising an amine and / or alkanolamine, and methylene diphenylamine (MDA) as the main components.

[0169] In an exemplary embodiment, the first liquid comprises polypropylene glycol (PPG) as the main component; the second liquid comprises a random copolymer of ethylene oxide and propylene oxide as the main component; and the third liquid comprises the depolymerization agent, comprising an amine, and toluene diamine (TDA) as the main components.

[0170] In preferred embodiments, the present process further comprises the step of: a) isolating the one or more first and / or second polyols from the first and second liquid, thereby obtaining recycled polyols, and optionally isolating the one or more amine compounds from the third liquid, thereby obtaining recycled amine compounds.

[0171] Accordingly, the present invention further encompasses the one or more first polyols, the one or more second polyols, and the one or more amine compounds obtained or obtainable by means of the depolymerization process as disclosed herein.

[0172] Advantageously, analytics of the recycled first polyols, second polyols, and amine compounds shows similar quality in comparison to the virgin polyols and amine compounds or the corresponding isocyanate compounds. Therefore, the recycled first polyols, second polyols, and amine compounds can be used in the production of PU materials, including PU foams, preferably flexible PU foams.

[0173] A further related aspect of the present invention relates to a method for manufacturing a recycled PU material, the method comprising the steps of: i) providing one or more recycled polyols obtained or obtainable by means of the process for the depolymerization of a PU material according to the present invention; ii) contacting the one or more recycled polyols with one or more isocyanate compounds, optionally in the presence of a catalyst, to form the recycled PU material, preferably a recycled PU foam. In particular embodiments, the present method comprises the steps of: i) depolymerizing a polyurethane material, made from at least two immiscible polyols, by means of the depolymerization process according to an aspect of the present invention or (preferred) embodiments thereof, thereby obtaining at least three phase-separated liquids comprising a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds; ii) isolating the one or more first and / or second polyols from the first and second liquid, thereby obtaining recycled polyols; iii) contacting the one or more recycled polyols with one or more isocyanate compounds, optionally in the presence of a catalyst, to form the recycled polyurethane material.

[0174] In preferred embodiments, the one or more isocyanate compounds are obtained by: isolating the one or more amine compounds from the third liquid (obtained by means of the present depolymerization process), thereby obtaining recycled amine compounds; and converting one or more recycled amine compounds into the corresponding isocyanate compound.

[0175] It should be noted that (preferred) embodiments and associated advantages of the process for the depolymerization of a polyurethane material according to the present invention are also (preferred) embodiments of the method for manufacturing a recycled polyurethane material according to the present invention and vice versa.

[0176] The term "recycled PU material" as used herein refers to a polyurethane material that has been prepared by using monomers obtained from the depolymerization of another polyurethane material. In other words, the (purified) monomers or oligomers (i.e., polyols and amine compounds) obtained or obtainable by means of the process for the depolymerization of a PU material according to the present invention can be (re)polymerized to form a new PU material.

[0177] It should be noted that the amine compounds are typically first converted to a (typically more reactive) isocyanate compound using standard methods disclosed in the art for example, in Ulrich, "Urethane Polymers", in Encyclopedia of Chemical Technology, Vol. 23, pp. 576-608(1983) and Backus et al., "Polyurethanes", in Encyclopedia of Polymer Science and Technology, Vol. 13, pp. 243-303(1988). The most common industrial method for converting amine compounds to isocyanate compounds involves a phosgenation method, wherein the amine is reacted with phosgene (COCH). Alternatively, the amine compound may be converted to an isocyanate compound by means of a dehydration method (e.g., using carbonyl diimidazole), a direct oxidation method (e.g., using hypochlorite and a phase transfer catalyst), or a thermal decomposition method of carbamates formed by the reaction of the amine compound with a carbonate compound in the presence of a metal catalyst.

[0178] In preferred embodiments, the one or more isocyanate compounds, used in the method for manufacturing a recycled PU material according to the present invention, are derived from one or more recycled amine compounds obtained or obtainable by means of the process for the depolymerization of a polyurethane material according to the present invention.

[0179] The one or more isocyanate compounds for the purposes of this invention are all isocyanate compounds comprising at least two isocyanate groups. Generally, it is possible to use all aliphatic, cycloaliphatic, arylaliphatic, preferably aromatic polyfunctional isocyanates known per se.

[0180] Individual examples of suitable isocyanate compounds that can be mentioned are tolylene 2,4 and 2,6-diisocyanate (TDI) and the corresponding isomer mixtures, diphenylmethane 4,4' , 2,4' and 2,2' diisocyanate (MDI) and the corresponding isomer mixtures, mixtures composed of diphenylmethane 4,4'- and 2,4'- diisocyanates, polyphenyl polymethylene polyisocyanates, mixtures composed of diphenylmethane 4,4'-, 2,4'- and 2,2'- diisocyanates and of polyphenyl polymethylene polyisocyanates (crude MDI) and mixtures composed of crude MDI and of tolylene diisocyanates. The organic diisocyanates and polyfunctional isocyanates may be used individually or in the form of mixtures.

[0181] In particular embodiments, the one or more isocyanate compounds are selected from the group consisting of 1,2-ethylene diisocyanate, 1,3-propane diisocyanate, 1,4-butane diisocyanate, 1,5- pentane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 2,3-toluene- diisocyanate, 2,4-toluene-diisocyanate, 3,4-toluene-diisocyanate, 2,6-toluene-diisocyanate, 4,4'- methylenediphenyl diisocyanate, 2, 4' -methylenediphenyl diisocyanate, 2,2'-methylenediphenyl diisocyanate, mixtures thereof, and including any isomeric, oligomeric, monomeric, or polymeric forms thereof.

[0182] In preferred embodiments, the one or more isocyanate compounds are selected from the group consisting of 2,3-toluene-diisocyanate, 2,4-toluene-diisocyanate, 3,4-toluene-diisocyanate, 2,6- toluene-diisocyanate, 4,4'-methylenediphenyl diisocyanate, 2,4'-methylenediphenyl diisocyanate, 2,2'-methylenediphenyl diisocyanate, mixtures thereof, and including any isomeric, oligomeric, monomeric, or polymeric forms thereof. In particular embodiments, contacting of the components results in the formation of a reaction mixture. Typically the polymerization reaction is (highly) exothermic and the internal temperature of the reaction mixture can reach a temperature of from 60 to 200 °C over a period of at least 5 minutes to at most 24 hours. Optionally, the reaction mixture can be heated to have a more uniform reaction temperature.

[0183] In particular embodiments, the contacting step is performed in the presence of a catalyst.

[0184] In the following, catalysts are described that can be used in the manufacturing of the recycled PU material as disclosed herein. These catalysts that catalyze the isocyanate-polyol and / or isocyanate- water reactions and / or isocyanate trimerization during PU formation are known per se to the skilled person. Catalysts used in this context may, for example, be any catalysts for the isocyanate-polyol (urethane formation) and / or isocyanate-water (amine and carbon dioxide formation) and / or isocyanate dimerization (uretdione formation), isocyanate trimerization (isocyanurate formation), isocyanate-isocyanate with CO2 elimination (carbodiimide formation) and / or isocyanate-amine (urea formation) reactions and / or "secondary" crosslinking reactions such as isocyanate-urethane (allophanate formation) and / or isocyanate-urea (biuret formation) and / or isocyanate-carbodiimide (uretonimine formation).

[0185] Suitable catalysts for the purposes of the present invention are, for example, substances which catalyze one of the aforementioned reactions, especially the gelling reaction (isocyanate-polyol), the blowing reaction (isocyanate-water) and / or the dimerization or trimerization of the isocyanate. Such catalysts are preferably nitrogen compounds, especially amines and ammonium salts, and / or metal compounds.

[0186] Examples of suitable nitrogen-containing compounds as catalysts for the purposes of the present invention are preferably amines, especially tertiary amines or compounds containing one or more tertiary amine groups, including the amines triethylamine, N,N-dimethylcyclohexylamine, N,N- dicyclohexylmethylamine, N,N-dimethylaminoethylamine, N,N,N',N'-tetramethylethylene-l ,2- diamine, N,N,N',N'-tetramethylpropylene-l ,3-diamine, N,N,N',N'-tetramethyl-l ,4-butanediamine, N,N,N',N'-tetramethyl-l ,6-hexanediamine, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N'- trimethylaminoethylethanolamine, N,N-dimethylaminopropylamine, N,N-diethylaminopropylamine, N,N-dimethylaminopropyl-N',N'-dipropan-2-olamine, 2-[[3-(dimethylamino)propyl]methylamino]- ethanol, 3-(2-dimethylamino)ethoxypropylamine, N,N-bis[3-(dimethylamino)propyl]amine,

[0187] N,N,N',N",N"-pentamethyldipropylenetriamine, l-[bis[3-(dimethylamino)propyl]amino]-2-propanol,

[0188] N,N-bis[3-(dimethylamino)propyl]-N',N'-dimethylpropane-l ,3-diamine, triethylenediamine, 1 ,4- diazabicyclo[2.2.2]octane-2-methanol, N,N'-dimethylpiperazine, 1 ,2-dimethylimidazole, N-(2- hydroxypropyl)imidazole, l-isobutyl-2-methylimidazole, N-(3-aminopropyl)imidazole, N- methylimidazole, N-ethylmorpholine, N-methylmorpholine, 2,2,4-trimethyl-2-silamorpholine, N- ethyl- 2,2-dimethyl-2-silamorpholine, N-(2-aminoethyl)morpholine, N-(2-hydroxyethyl)morpholine, bis(2- morpholinoethyl) ether, N,N'-dimethylpiperazine, N-(2-hydroxyethyl)piperazine, N-(2- aminoethyl)piperazine, N,N-dimethylbenzylamine, N,N-dimethylaminoethanol, N,N- diethylaminoethanol, 3-dimethylamino-l -propanol, N,N-dimethylarninoethoxyethanol, N,N- diethylaminoethoxyethanol, bis(2-dimethylaminoethyl) ether, N,N,N'-trimethyl-N'-(2- hydroxyethyl)bis(2-aminoethyl) ether, N,N,N'-trimethyl-N-3'-arninopropyl bisaminoethyl ether, tris(di- methylaminopropyl)hexahydro-l ,3,5-triazine, 1 ,8-diazabicyclo[5.4.0]undec-7-ene, 1 ,5- diazabicyclo- [4.3.0]non-5-ene, 1 ,5,7-triazabicyclo[4.4.0]dec-5-ene, N-methyl-1 ,5,7- triazabicyclo[4.4.0]dec-5-ene, 1 ,4,6-triazabicyclo[3.3.0]oct-4-ene, 1 ,1 ,3,3-tetramethylguanidine, tert-butyl-1 ,1 ,3,3- tetramethylguanidine, guanidine, 3-dimethylaminopropylurea, 1 ,3-bis[3- (dimethylamino)propyl]urea, bis-N,N-(dimethylaminoethoxyethyl)isophorone dicarbamate, 3- dimethylamino-N,N- dimethylpropionamide and / or 2,4,6-tris(dimethylaminomethyl)phenol; and / or ammonium salts thereof.

[0189] Suitable metal compounds as catalysts, also referred to hereinafter as metallic catalysts, for the purposes of the present invention are all metal compounds according to the prior art which catalyze one of the abovementioned isocyanate reactions and / or can be used for production of polyurethane materials, such as polyurethane foams. They may be selected, for example, from the group of the metalorganic or organometallic compounds, metal-organic or organometallic salts, organic metal salts, inorganic metal salts, and / or from the group of the charged or uncharged metallic coordination compounds, especially the metal chelate complexes.

[0190] Suitable organometallic salts and organic metal salts, especially as defined above, as catalysts in the context of the present invention are, for example, organotin, tin, zinc, bismuth and potassium salts, in particular corresponding metal carboxylates, alkoxides, thiolates and mercaptoacetates, for example dibutyltin diacetate, dimethyltin dilaurate, dibutyltin dilaurate (DBTDL), dioctyltin dilaurate (DOTDL), dimethyltin dineodecanoate, dibutyltin dineodecanoate, dioctyltin dineodecanoate, dibutyltin dioleate, dibutyltin bis(n-lauryl mercaptide), dimethyltin bis(n-lauryl mercaptide), monomethyltin tris(2-ethylhexyl mercaptoacetate), dimethyltin bis(2-ethylhexyl mercaptoacetate), dibutyltin bis(2- ethylhexyl mercaptoacetate), dioctyltin bis(isooctyl mercaptoacetate), tin(ll) acetate, tin(ll) 2- ethylhexanoate (tin(ll) octoate), tin(ll) isononanoate (tin(ll) 3,5,5-trimethylhexanoate), tin(ll) neodecanoate, tin(ll) ricinoleate, tin(ll) oleate, zinc(ll) acetate, zinc(ll) 2-ethylhexanoate (zinc(ll) octoate), zinc(ll) isononanoate (zinc(ll) 3,5,5-trimethylhexanoate), zinc(ll) neodecanoate, zinc(ll) ricinoleate, bismuth acetate, bismuth 2-ethylhexanoate, bismuth octoate, bismuth isononanoate, bismuth neodecanoate, potassium formate, potassium acetate, potassium 2-ethylhexanoate (potassium octoate), potassium isononanoate, potassium neodecanoate and / or potassium ricinoleate.

[0191] Optionally, the contacting step in the method for manufacturing a recycled PU material of the present invention may further include the addition of any of the conventional additional reactants or additives known in the art such as for example chain extenders or curatives (relatively low molecular weight active hydrogen-containing compounds such as glycols and di- or polyamines), physical or chemical blowing agents, flame retardants, surfactants, fillers, stabilizers, anti-oxidants, colorants, polymers other than the PU polymer (e.g., styrene-acrylonitrile copolymers such as are found in polymer polyols).

[0192] In preferred embodiments, the recycled PU material is a PU foam; preferably a flexible PU foam.

[0193] The invention is illustrated but not limited by the following examples.

[0194] EXAMPLES

[0195] Materials and Methods

[0196] The following describes the materials and methods used for all examples unless otherwise stated. Diethanolamine (99% purity) was purchased from Thermo Scientific. Acetonitrile (99.9 % purity) and tetrahydrofuran (THF) (99.8 % purity) used for analysis of respectively HPLC and GPC were purchased from Fisher Scientific.

[0197] Three different industrially available PU foams, PU-A; PU-B; and PU-C as termed herein, were subjected to the present depolymerization process in order to recover different polyol fractions. Each PU foam was a flexible MDI-based foam made from at least two different polyols.

[0198] Also TDI-based foams, PU-D, were tested in the present depolymerization process.

[0199] Gel Permeation Chromatography (GPC) analysis was used to examine the distribution of different components in the phase-separated liquids. Briefly, an Agilent Technologies 1100 series GPC was used, whereby 5 mg of sample was dissolved in THF (> 99.8% purity, stabilized with BHT). The injection volume comprised about 20 pL and a Phenogel 50 A and Phenogel 100A column were used. The equipment further comprises an RID detector to measure the concentration of each component. Calibration was done by using pure polyols, amine compounds, and depolymerization agents. Example 1 - Depolymerization of PU-A

[0200] In a first example, PU-A was used to demonstrate the improved efficiency of the present depolymerization process.

[0201] Firstly, shredded PU-A (5.036 g) and diethanolamine (DEA, 10.020 g) were charged in a weight ratio of 1.0:2.0 to a three-neck round bottom flask to form a depolymerization mixture. The flask was further equipped with a water condenser and stirring bar and the depolymerization mixture was kept under an inert (argon) atmosphere. Next, the flask was transferred to a heating plate set to a temperature of 240.0 °C to initiate heating of the depolymerization mixture. After reaching an internal temperature of approximately 160 °C, the shredded PU-A began to dissolve in the diethanolamine and complete dissolution was achieved after about 5 minutes. Once complete dissolution was reached, heating was continued for about 30 minutes. After about 30 minutes, the heating plate was removed and the flask was allowed to cool to 20 °C. After cooling, 14.932 g of three phase-separated liquids was formed.

[0202] GPC analysis

[0203] For sample 1, 0.013 g of the first liquid (upper layer) was taken and diluted in 1.963 g THF (dilution of 151 times); for sample 2, 0.020 g of the second liquid (middle layer) was taken and diluted in 3.060 g THF (dilution of 150 times); and for sample 3, 0.021 g of the third liquid (lower layer) was taken and diluted in 3.121 g THF (dilution of 149 times) and each sample was subjected to GPC analysis as described herein above. In addition, a comparative sample 1 was taken before formation of the three phase-separated liquids by dissolving 0.018 g of product in 2.695 g of tetrahydrofuran (dilution of about 152 times).

[0204] As shown in FIG.l, the present process provides a more efficient separation of 4,4'-methylenedianiline (MDA), the carbamate or urea compounds, a first polyol, and a second polyol after depolymerizing PU-A. In particular, comparative sample 1 comprises a mixture of the first polyol, the second polyol, and significant amounts of MDA. In contrast, for sample 1-3, the upper layer and middle layer clearly have a distinct polyol profile, although the retention times in this case are comparable. This demonstrates that the present process advantageously allows the effective separation of a complex foam into distinct polyol products. In addition, the carbamate or urea compounds, MDA, and diethanolamine are predominantly observed in the middle layer. Conversely, these same components exhibit the lowest presence in the upper layer. The bottom layer comprises remaining aromatic compounds and diethanolamine.

[0205] Further analysis of the polyols revealed that the first polyol was a copolymer of ethylene oxide and propylene oxide having a number average molecular weight (Mn) between 3000 g / mol and 5000 g / mol and an hydroxyl (OH) value of 36 mg KOH / g and the second polyol was a polypropylene glycol having an Mn between 2000 g / mol and 3000 g / mol and an OH value of 58 mg KOH / g.

[0206] Mass balance

[0207] To estimate the mass of each phase-separated liquid, the volume and density of each layer was used. From each liquid, 100 pL was pipetted and weighed using an analytical balance. The weights were as follows: the first liquid weighed 0.089 g, the second liquid weighed 0.094 g, and the third liquid weighed 0.102 g. The corresponding densities are 0.89 g / cm3, 0.94 g / cm3, and 1.02 g / cm3, respectively. The volume of each liquid was then determined by measuring the height of the layers and the radius of the vial. The vial had a radius of 1.25 cm, and the heights of the layers from top to bottom were 0.35 cm, 0.85 cm, and 1.80 cm.

[0208] Using the density and volume, the masses obtained from top to bottom are 1.526 g, 3.922 g, and 8.977 g, respectively. Together, this gives a theoretical total mass of 14.425 g which is close to the experimentally determined mass of 14.932 g.

[0209] Example 2 - Depolymerization of PU-A with variable reaction time and temperature

[0210] In a second example, PU-A was subjected to two different depolymerization conditions. Firstly, the same depolymerization process was used as described in Example 1, but instead applying heating for 5 minutes at 240.0 °C. Secondly, the same depolymerization process was used as described in Example 1, but instead by heating for 30 minutes at 160.0 °C.

[0211] GPC analysis

[0212] GPC samples were taken from the respective phase-separated liquids and compared to the composition of the liquids obtained in Example 1. From FIG.2-3, it follows that a longer reaction time and / or higher reaction temperature results in a higher yield of MDA, while the content of carbamate or urea compounds decreases. These experiments demonstrate that the present process advantageously allows to tune the composition of the three phase-separated liquids.

[0213] Example 3 - Depolymerization of PU-B and PU-C

[0214] In a third example, PU-B was subjected to the same depolymerization process as described herein in Example 1 by charging the PU material and depolymerization agent in a 1.0:2.0 weight ratio in a three- neck round bottom flask. The same procedure was repeated for PU-C.

[0215] GPC analysis GPC samples from the respective phase-separated liquids exhibited a similar distribution of components in a first liquid (top layer), second liquid (middle layer), and third liquid (bottom layer), as obtained in Example 1.

[0216] As shown in FIG.4 for PU-B, the present process provides a similar distribution of a first polyol, a second polyol, and MDA across three phase-separated liquids. Hence, depolymerization of PU foams PU-A and PU-B resulted in the formation of similar phase-separated liquids. Further analysis of the polyols revealed that the first polyol was a copolymer of ethylene oxide and propylene oxide having a number average molecular weight (Mn) between 3000 g / mol and 5000 g / mol and an hydroxyl (OH) value of 36 mg KOH / g and the second polyol was also a copolymer of ethylene oxide and propylene oxide having an Mn between 2000 g / mol and 4000 g / mol and an OH value of 48 mg KOH / g.

[0217] Depolymerization of PU-C resulted in a more complex GPC chromatogram as shown in FIG.5. In particular, the upper layer and middle layer clearly have a different polyol profile compared to what was obtained for PU-A and PU-B. In particular, it was found that PU-C comprises five polyols, which are all copolymers of ethylene oxide and propylene oxide. Further analysis revealed that the upper layer contained one polyol with an Mnbetween 2000 g / mol and 4000 g / mol and an OH value of 28 mg KOH / g, another polyol with an Mnbetween 2000 g / mol and 4000 g / mol and an OH value of 48 mg KOH / g, and yet another polyol with an Mnbetween 4000 g / mol and 6000 g / mol and an OH value of 34 mg KOH / g. The second layer comprised one polyol with an Mnbetween 2000 g / mol and 3000 g / mol and an OH value of 168 mg KOH / g, and the third layer comprised a polyol with an Mnbetween 2000 g / mol and 3000 g / mol and an OH value of 170 mg KOH / g.

[0218] These data demonstrate that the present depolymerization process can be applied to improve the recovery of valuable chemicals from PU materials of varying composition.

[0219] Example 4 - Depolymerization of PU-D

[0220] In a fourth example, PU-D was subjected to the same depolymerization process as described herein in Example 1 by charging the PU material and depolymerization agent in a 1.0:2.0 weight ratio in a three-neck round bottom flask.

[0221] GPC analysis

[0222] GPC samples from the respective phase-separated liquids exhibited a similar distribution of components in a first liquid (top layer), second liquid (middle layer), and third liquid (bottom layer), as obtained in Example 1. Further analysis of the layers revealed that the upper layer comprises one polyol and the middle layer comprises another polyol. In particular, it was found that PU-D comprises two polyols, which are all copolymers of ethylene oxide and propylene oxide. Further analysis revealed that the first polyol comprised in the upper layer has a number average molecular weight (Mn) between 2000 g / mol and 4000 g / mol and an hydroxyl (OH) value of 48 mg KOH / g; and the second polyol comprised in the middle layer has an Mn between 2000 g / mol and 3000 g / mol and an OH value of 42 mg KOH / g. Toluenediamine was found in all layers.

[0223] Example 5 - Depolymerization of PU-A with another depolymerization agent

[0224] In a fifth example, PU-A was subjected to the present depolymerization process as defined in Example 1, but using monoethanolamine (MEA, 10.020 g to obtain a weight ratio of 1.0:2.0) instead.

[0225] The resulting three phase-separated liquids were subjected to GPC analysis and revealed a similar distribution of components in a first liquid (top layer), second liquid (middle layer), and third liquid (bottom layer), as obtained in Example 1. However, in this example, the polyols were found in the top and bottom layer, while the middle layer predominantly comprised MEA. These data demonstrate that the present depolymerization process can be applied to improve the recovery of valuable chemicals from PU materials using depolymerization agents of varying composition.

Claims

CLAIMS1. A process for the depolymerization of a polyurethane material made from at least two immiscible polyols, the process comprising the steps of: a) contacting the polyurethane material with a depolymerization agent comprising an amine and / or alkanolamine to obtain a depolymerization mixture; b) heating the depolymerization mixture to a temperature of from 80.0 to 250.0 °C; c) allowing the formation of at least three phase-separated liquids; and d) separating the at least three phase-separated liquids; wherein the at least three phase-separated liquids comprise a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising the depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds; and wherein the depolymerization agent is immiscible with each polyol.

2. The process according to claim 1, wherein the depolymerization agent comprises an amine comprising at least one primary amino functional group and / or at least one secondary amino functional group, preferably wherein the amine is selected from the group consisting of pentane-l,5-diamine, (dibutyl)amine, dodecylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and mixtures thereof.

3. The process according to claim 1, wherein the depolymerization agent comprises an alkanolamine comprising at least one hydroxyl functional group and at least one amino functional group, preferably wherein the alkanolamine has the following structural Formula (la) or (II)(la), (II) wherein,R3,R2, R3are each independently selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl, arylalkyl; X1is hydrogen; and X2, X3are each independently selected from thegroup consisting of hydrogen, alkyl, alkenyl, and cycloalkyl; with the provision that at least one of X2, X3is hydrogen.

4. The process according to any one of claims 1 to 3, wherein step a) comprises contacting the polyurethane material with the depolymerization agent comprising an amine and / or alkanolamine in a weight ratio of from 1.0:1.1 to 1.0:5.0 to obtain the depolymerization mixture.

5. The process according to any one of claims 1 to 4, wherein step b) is carried out for a period of from 5 minutes to 24 hours.

6. The process according to any one of claims 1 to 5, wherein step c) comprises cooling or allowing to cool, preferably cooling or allowing to cool to 20 °C.

7. The process according to any one of claims 1 to 6, wherein the polyurethane material is polyurethane scrap or foam.

8. The process according to any one of claims 1 to 7, wherein the one or more first polyols comprise -[OCHfCHajCHz]- as the main repeating unit and the one or more second polyols comprise -[OCHfCHajCHz]- and -[OCH2CH2]- as the main repeating units.

9. The process according to any one of claims 1 to 8, wherein the difference in number average molecular weight (Mn) between the one or more first polyols and the one or more second polyols is at least 250 g / mol, or at least 500 g / mol, or at least 750 g / mol, or at least 1000 g / mol, as determined by Gel Permeation Chromatography.

10. The process according to any one of claims 1 to 9, wherein the one or more first polyols has a number average molecular weight (Mn) of at least 1500 g / mol, as determined by Gel Permeation Chromatography.

11. The process according to any one of claims 1 to 9, wherein the one or more first polyols are propylene glycol and the one or more second polyols are a copolymer of ethylene oxide and propylene oxide, preferably a copolymer of ethylene oxide and propylene oxide with a high ethylene oxide content.

12. The process according to any one of claims 1 to 10, wherein the one or more amine compounds are selected from the group consisting of 1,2-ethylenediamine, 1,3- propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, isophorone diamine, 2,3-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 2,6- diaminotoluene, 4,4'-methylenedianiline, 2,4'-methylenedianiline, 2, 2' -methylenedianiline, oligomeric derivatives thereof and / or mixtures thereof.

13. The process according to any one of claims 1 to 12, wherein the process further comprises the step of: e) isolating the one or more first and / or second polyols from the first and second liquid, thereby obtaining recycled polyols, and optionally isolating the one or more amine compounds from the third liquid, thereby obtaining recycled amine compounds.

14. A method for manufacturing a recycled polyurethane material, the method comprising the steps of: i) depolymerizing a polyurethane material, made from at least two immiscible polyols, by means of the process according to any one of claims 1 to 12, thereby obtaining at least three phase-separated liquids comprising a first liquid comprising one or more first polyols; a second liquid comprising one or more second polyols; and a third liquid comprising depolymerization agent, one or more amine compounds, and optionally one or more carbamate compounds and / or urea compounds; ii) isolating the one or more first and / or second polyols from the first and second liquid, thereby obtaining recycled polyols; iii) contacting the one or more recycled polyols with one or more isocyanate compounds, optionally in the presence of a catalyst, to form the recycled polyurethane material.

15. The method according to claim 14, wherein the one or more isocyanate compounds are obtained by: isolating the one or more amine compounds from the third liquid, thereby obtaining recycled amine compounds; and converting one or more recycled amine compounds into the corresponding isocyanate compound.

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