Method of recovering polytetrahydrofuran derived from a polyurethane product

Abstract

There is provided a method for recovering a polytetrahydrofuran component from a first mixture comprising the polytetrahydrofuran component, a polyamine component and a chemolysis component, the method comprising the following steps in order: i) removing at least a part of the chemolysis component from the first mixture by distillation to form a second mixture; ii) mixing the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuranrich phase and an acidic phase, and isolating the polytetrahydrofuranrich phase; iii) mixing the polytetrahydrofuranrich phase with an ion exchange compound to form a third mixture; and iv) filtering the third mixture to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component.

Description

1 EU-51181METHOD OF RECOVERING POLYTETRAHYDROFURAN DERIVED FROM A POLYURETHANE PRODUCTFIELD OF INVENTION

[0001] The present disclosure relates to a method of recovering a polytetrahydrofuran (pTHF; also called poly(tetramethylene)glycol or PTMEG) component from a first mixture comprising the pTHF component, a polyamine component and a chemolysis component. The first mixture is obtained from the chemolysis of a polyurethane product. The present disclosure also relates to a recovered pTHF component obtained from the method described herein, and a method of preparing a polyurethane-based product which employs the recovered pTHF component.BACKGROUND

[0002] Polytetrahydrofuran (pTHF) is a key component in the polyurethane industry, given pTHF is frequently used in the manufacture of polyurethane products. In order to reduce the reliance on fossil fuels for the supply of pTHF, efforts have been made to recover or recycle pTHF from pTHF-containing polyurethane products (e.g., waste polyurethane products from a factory and / or post-consumer).

[0003] A known way to recover pTHF is by chemically recycling a polyurethane. Chemical recycling of polyurethane is a process which uses a chemolysis agent to break down (or depolymerise) the polyurethane into a polyol component and a poly amine component (individually or collectively referred to as a “recyclate” or “mixture”). Chemical recycling methods include aminolysis and hydro-glycolysis / glyco-hydrolysis / glycolysis. In aminolysis, a chemolysis agent (e.g., an alkanolamine) is used to break down the polyurethane. In hydro-glycolysis / glyco-hydrolysis, a chemolysis agent (e.g., a glycol) and water are used to break down the polyurethane. Typically, the polyol component and the polyamine component are separated after chemical recycling. The obtained polyol component comprises the polyol used to make the polyurethane (termed “virgin polyol”), and the obtained poly amine component is derived from the polyisocyanate component used to make the polyurethane. However, the polyol component often contains high amounts of polyamine compounds, as well as other impurities, which means that the polyol component may not be suitable to make a new polyurethane product without further purification.

[0004] A known purification method of the obtained polyol component derived from chemolysis of polyurethane includes ion exchange treatment (which also involves2 EU-51181 adding large amounts of solvent) followed by distillation of the chemolysis agent and the solvent. The ion exchange treatment typically removes polyamine salts. This method is satisfactory for purifying polyol components comprising poly ether polyols made from ethylene oxide and / or propylene oxide. However, this known method is not satisfactory for purifying polyol components comprising pTHF polyol, as is demonstrated in the Examples section herein, because the purity of the recovered pTHF is poor.

[0005] Thus, there is a need to improve the method of recovering pTHF from a mixture (or recy elate) derived from a chemolysis reaction of pTHF -containing polyurethane product, such that the pTHF can be recovered with greater purity. Moreover, there is a need to recover the pTHF without the addition of organic solvents, which are required to be removed at the end of the process. The removal of the organic solvents is therefore an extra step and uses energy.

[0006] The present disclosure addresses the problems and needs mentioned above.SUMMARY

[0007] In a first aspect, there is provided a method for recovering a polytetrahydrofuran component from a first mixture comprising the polytetrahydrofuran component, a polyamine component and a chemolysis component, the method comprising the following steps in order: i) removing at least a part of the chemolysis component from the first mixture by distillation to form a second mixture; ii) mixing the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuran-rich phase and an acidic phase, and isolating the polytetrahydrofuran-rich phase; iii) mixing the polytetrahydrofuran-rich phase with an ion exchange compound to form a third mixture; and iv) filtering the third mixture to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component.

[0008] The method of the present disclosure, which requires a distillation step for removing the chemolysis agent, an acidic wash / extraction step, an ion exchange step and a filtration step, in that order, results in excellent purity of the recovered pTHF component. Specifically, the recovered pTHF component comprises a very high amount of pTHF and a very low amount of polyamine compounds. Moreover, there is no addition of3 EU-51181 organic solvent during the purification / recovery process which requires a complex separation technique. The present method therefore provides a simple, economical, highly effective method for recovering pTHF from a mixture derived from the chemolysis of a polyurethane.

[0009] In a second aspect, there is provided a product mixture comprising the polytetrahydrofuran component obtained according to the method as described herein.

[0010] In a third aspect, there is provided a method of preparing a polyurethane-based product, comprising mixing a polyisocyanate component and the product mixture comprising the polytetrahydrofuran component as described herein.

[0011] The embodiments described should not be read to limit or otherwise narrow the scope of any inventive concepts otherwise provided by the present disclosure. While multiple embodiments are disclosed, other embodiments will become apparent to those skilled in the art from the following description and figure. Accordingly, the description and figure are to be regarded as illustrative rather than restrictive.BRIEF DESCRIPTION OF THE FIGURES

[0012] Figure 1 shows the order of the method steps of the present disclosure.DETAILED DESCRIPTION

[0013] The present disclosure relates to a method of recovering a polytetrahydrofuran (pTHF) component from a first mixture comprising the pTHF component, a polyamine component and a chemolysis component. The first mixture is obtained from the chemolysis of a polyurethane product.

[0014] As used herein, the phrase “method of recovering” pTHF means a method of separating out the pTHF from the first mixture, e.g., such that the pTHF can be subsequently used in another application.

[0015] As used herein, the term “component” is not limited to containing only one type of compound, but may contain at least one type of compound, including two or more types of compound. For instance, the “chemolysis component” may comprises one, two, three or more different types of chemolysis agents / compounds / components.

[0016] [Chemolysis of polyurethane product to form the first mixture]

[0017] The first mixture is obtained from the chemolysis of a polyurethane-based product.

[0018] Herein, chemolysis refers to the break down (or depolymerisation) of the polyurethane into a polyol component and a polyamine component (individually or collectively4 EU-51181 referred to as a “recyclate” or “mixture”). Chemolysis methods include, but are not limited to, aminolysis and hydro-glycolysis / glyco-hydrolysis / glycolysis. In aminolysis, a chemolysis component (termed an “aminolysis component”, e.g., an alkanolamine) is used to break down the polyurethane. In hydro-glycolysis / glyco-hydrolysis, a chemolysis component (termed a “glycolysis component”, e.g., a glycol) and water are used to break down the polyurethane. The skilled person would be aware of the different chemolysis methods and how to carry out the methods on a given polyurethane product.

[0019] The first mixture, which is obtained from the chemolysis of a polyurethane product, comprises the polytetrahydrofuran component, a poly amine component and a chemolysis component. Other components may also be present.

[0020] In one embodiment, the method of the present disclosure further comprises a step a) of obtaining the first mixture, the step a) occurring before step i) and comprising: a) mixing a polyurethane-based product with a chemolysis component to obtain the first mixture, wherein the polyurethane-based product is produced from a polytetrahydrofuran component.

[0021] The mixing of the chemolysis component with the polyurethane-based product may be performed under standard conditions, or the mixture may be heated to a temperature between 50°C to 300°C, or from 100°C to 300°C. Optionally, the reaction is carried out under an inert atmosphere, such as N2. Based upon the particular polyurethane-based product and the particular chemolysis component and process, the skilled person would know the suitable conditions to achieve chemolysis.

[0022] The polyurethane-based product is preferably in ground or in pellet, flake or bead form.

[0023] In one embodiment, the step a) forms a split-phase mixture comprising a first mixture and a fourth mixture, and wherein step a) further comprises isolating the first mixture. The fourth mixture may be, for example, a phase comprising polyamine component in greater amount or concentration than the first mixture. The fourth mixture may be, for example, a phase comprising pTHF component in smaller amount or concentration than the first mixture.

[0024] In one embodiment, the chemolysis component is selected from an aminolysis component or a glycolysis component.

[0025] In one embodiment, the chemolysis component is an aminolysis component. The aminolysis component may be any known agent used in the art.

[0026] In one embodiment, the aminolysis component has the following structure:5 EU-51181R”-Y-NHR’ wherein R’ is H or a substituted or unsubstituted hydrocarbon group which may contain one or more unsaturated carbon to carbon bonds and / or one or more heteroatoms in a main chain of the hydrocarbon group; Y is a substituted or unsubstituted hydrocarbon group which may contain one or more unsaturated carbon to carbon bonds and / or one or more heteroatoms in a main chain of the hydrocarbon group; and R” is an isocyanatereactive group. In one embodiment, R’ is a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, or from 1 to 5 carbon atoms, or from 1 to 3 carbon atoms. In one embodiment, Y is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or 1 to 6 carbon atoms, or 1 to 3 carbon atoms. In one embodiment, R” is -OH, -NHR, -NH2, wherein R is an alkyl group, preferably an alkyl group having 1 to 5 carbon atoms. In one embodiment, R” is -OH.

[0027] Suitable aminolysis components include alkanolamines and polyamines. The polyamines may be diamines, polyamines or polyetheramines. Suitable examples of polyamines include 1,2-ethylenediamine, 1,4-butanediamine, 1,6-diaminohexane, 1,8- diaminooctane, 1,12-di aminododecane, N,N'-dimethyl-l,6-hexanediamine, N,N'- dimethylethylenediamine, N,N'-dimethyl- 1,3 -propanediamine, xylylenediamine, 4,4'- diaminodiphenylmethane, 4,4'-methylenebis(cyclohexylamine), isophoronediamine, diethelenetriamine, tetraethylenepentamine, triethylenetetramine, dipropylenetriamine, polyethylenimine, 2,2'-(ethylenedioxy)bis(ethylamine), poly(ethylene glycol) diamine, polypropylene glycol) bis(2-aminopropyl ether), O,O'-bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol, poly(tetramethylene ether glycol)-block-polypropylene glycol diamine and poly(tetramethylene ether glycol) diamine. Suitable examples of alkanolamines include 2-methylethanolamine (N-MEA), 2-ethylethanolamine (N-EEA), 2-butylethanolamine (N-BEA), 2-(isopropyl ethanolamine), amino-2-propanol, 5 -amino- 1 -pentanol, 6- amino-1 -pentanol, 10-amino-l -decanol, 3 -amino- 1 -propanol, di glycolamine, monoethanolamine (MEA), 2-(2-aminoethylamino) ethanol (2-AEAE), 4-amino-l- butanol, 2-amino-l -butanol, l-amino-2-butanol, 2-amino-3 -methyl- 1 -butanol, 3-amino- 2 -m ethyl- 1 -butanol, 3 -amino- 1 -propanol, 2-amino-2-m ethyl- 1 -propanol, 2-amino-l- propanol, methanolamine, heptaminol, 2-(ethylamino)ethanol, 3 -methylamino- 1- propanol, dimethanol amine, dimethylethanolamine, diethanolamine and diisopropanolamine.6 EU-51181

[0028] In one embodiment, the aminolysis component is an alkanolamine. In one embodiment, the alkanolamine contains a primary or secondary amine group and has a molar mass of about 150 g / mol or less. In one embodiment, the aminolysis agent is monoethanolamine or 2-methylethanolamine (N-MEA).

[0029] The glycolysis component may be any known agent used in the art. In one embodiment, the glycolysis component is a diol compound, preferably a diol compound containing 2 to 6 carbon atoms. Suitable diol compounds include monoethylene glycol (MEG), di ethylene glycol (DEG), propylene glycol, dipropylene glycol and 1,4 -butanediol. Another suitable glycolysis component is glycerol.

[0030] In one embodiment, the chemolysis, such as hydro-glycolysis / glyco- hydrolysis / glycolysis, may employ a catalyst. Suitable catalysts are known in the art and include metal hydroxides, such as NaOH and KOH. Other non-limiting examples of catalysts suitable for use in the method of the present disclosure may include (organo)tin, tertiary amine and bismuth catalysts such as dimethyltin dichloride, butyltin trichloride, dimethyltin dilaurate, dimethyltin dioleate, dimethyltin mercaptide, dibutyltin diacetate, dimethyltin dineodecanoate, bismuth(lll) neodecanoate, bismuth 2- ethylhexanoate and triphenylbismuth, alkali metals, titanium(IV) alkoxides such as titanium(IV) propoxide, titanium(IV) butoxide and titanium(IV) tert- butoxide, alkoxide complexes of lithium and potassium such as lithium t-butoxide and potassium t-butoxide, tetrabutyltitanate, potassium acetate, potassium 2- ethylhexanoate, calcium 2- ethylhexanoate, bismuth(lll) trifluorom ethanesulfonate, iron (111) acetyl acetonate, aluminium isopropoxide, dimethylimidazole, potassium adipate and in general urethane-reaction promoting catalysts.

[0031] In one embodiment, step a) comprises steps al) to a4): al) mixing the polyurethane-based product with a chemolysis (aminolysis) component to form a reaction mixture, wherein the chemolysis component is an alkanolamine, a2) heating the reaction mixture to form a product mixture; a3) cooling the product mixture to obtain a split-phase mixture comprising a first mixture and a fourth mixture; and a4) isolating the first mixture.

[0032] The step of isolating the first mixture may be achieved by conventional and known means, such as by the use of a separating funnel or by siphoning the first mixture from a container.7 EU-51181

[0033] In one embodiment, the aminolysis comprises mixing the aminolysis component with the polyurethane-based product. The polyurethane-based product is preferably in ground or in pellet, flake or bead form. Optionally, a catalyst is added to the mixture at this stage, such as a metal hydroxide and preferably KOH or NaOH. The skilled person would know a suitable quantity of catalyst to use. Optionally, the reaction is carried out under an inert atmosphere, such as N2. The mixture is then heated up, e.g., to above 80°C, or 100°C to 200°C, or 125°C to 175°, or to about 150°C, and stirred for the required period of time for the polyurethane to break down. This time period may be from 30 mins to 10 hours, or from 1 hour to 5 hours, or from 1 hour to 4 hours. The mixture is then cooled to obtain a split-phase, and the first mixture may be isolated.

[0034] In one embodiment, the aminolysis comprises mixing 50 to 200 parts by weight of alkanolamine and 100 parts by weight of polyurethane-based product, and heating the newly formed mixture to between 100°C and 200°C. After complete dissolution of the polyurethane-based product, the mixture is stirred for 1 to 5 hours at the specified temperature. The reaction is then cooled down to below 100°C to obtain a split-phase mixture (comprising the first mixture as one phase, and the fourth mixture as the other phase). Both phases may then be discharged in separate containers to collect the first mixture and the fourth mixture.

[0035] In one embodiment, the hydro-glycolysis comprises mixing 50 to 200 parts by weight of diol, 100 parts by weight of polyurethane-based product and optionally 0.01 to 1 parts by weight of metal hydroxide (such as KOH), and heating the newly formed mixture to 150°C to 250°C. After complete dissolution of the polyurethane-based product, the mixture is stirred for 1 to 5 hours at the specified temperature. Water is then added to the mixture, and the mixture is stirred for 1 to 5 hours at the specified temperature. The reaction mixture is then cooled down to below 100°C to obtain a split-phase mixture (comprising the first mixture as one phase, and the other mixture as the other phase). Both phases may then be discharged in separate containers to collect the first mixture and the other mixture.

[0036] Polyurethane-based products are made by reacting a polyol component with an isocyanate component, optionally in the presence of additives such as catalysts, surfactants, chain extenders, blowing agents and the like. The polyurethane-based product is not particularly limited as long as the polyurethane-based product was made using a polyol component comprising pTHF component.8 EU-51181

[0037] The isocyanate component is not particularly limited, and any known isocyanate component may be used. The isocyanate component may comprise an aliphatic polyisocyanate, an aromatic polyisocyanate, a prepolymer of a polyisocyanate, or a combination thereof. Preferably, the isocyanate component comprises an aromatic polyisocyanate compound, more preferably a methylene diphenyl diisocyanate (MDGbased compound. The isocyanate component may be pure MDI, polymeric MDI, or may be a prepolymer thereof, i.e., a prepolymer made from MDI and a polyol (collectively termed “MDI-based”). According to an embodiment, the isocyanate component may comprise at least 50 weight%, or at least 75 weight%, or at least 80 weight%, or at least 85 weight%, or at least 90 weight%, or at least 95 weight%, or about 100 weight%, of an aromatic polyisocyanate, such as MDI-based polyisocyanate component, based upon the total weight of the isocyanate component.

[0038] Examples of aliphatic polyisocyanates suitable for use in the isocyanate component include, but are not limited to, hexamethylene diisocyanate (HDI), tetraalkyl xylene diisocyanate, cyclohexane diisocyanate, 1,12-dodecane diisocyanate, 1,4- tetramethylene diisocyanate, 1,3- and 1,4-cyclohexane diisocyanate, 1-isocyanato- 3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate), 4,4'-, 2,2'- or 2,4'-dicyclohexyl-methane diisocyanate, as well as the corresponding isomer mixtures.

[0039] Examples of aromatic polyisocyanates suitable for use in the isocyanate component include, but are not limited to, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'- or 2,4'- or 2,2'-diphenylmethane diisocyanate (MDI), polymeric MDI, 2,4- or 2,6- toluene diisocyanate (TDI), dianisidine diisocyanate, bitolylene diisocyanate, naphthal ene-l,4-diisocyanate and diphenylene 4,4'-diisocyanate.

[0040] Prepolymers formed from the reaction of a polyisocyanate (e.g., MDI, modified MDI and / or polymeric-MDI) with a polyol may also be suitable for use in the isocyanate component. The polyol may be a polyether polyol, a polyester polyol, a polycarbonate polyol, a polycaprolactone polyol, other polyol which may be used either individually or in combinations of two or more, or a combination thereof. In addition, the polyol may be a copolymer of one or more of a polyether polyol, a polyester polyol, a polyether-ester polyol, a polycarbonate polyol, a polycaprolactone polyol, or other polyol.

[0041] According to an embodiment, the isocyanate component may comprise an isocyanate- terminated prepolymer. The isocyanate-terminated prepolymer may be prepared by9 EU-51181 reaction of an excessive amount of a polyisocyanate having at least 80 weight%, or at least 85 weight%, or at least 90 weight%, or at least 95 weight%, of MDI (such as 4,4'- MDI) with a suitable difunctional polyol in order to obtain a prepolymer having a desired NCO value. Methods to prepare prepolymers have been described in the art. The relative amounts of polyisocyanate and polyol depend on their equivalent weights and on the desired NCO value and can be determined easily by those skilled in the art. The NCO value of the isocyanate-terminated prepolymer is preferably above 3%, preferably above 5%, more preferably above 8%, and more preferably above 10%. The NCO value of the isocyanate-terminated prepolymer may be from 3% to 40%, or from 5% to 30%, or from 10% to 20%.

[0042] The polyol component comprises pTHF component. The pTHF component comprises at least one type of pTHF compound, but may comprise 2 or more types of pTHF compound. The pTHF component used to make the polyurethane-based product may be termed “virgin pTHF”.

[0043] In one embodiment, the polyol component comprises at least 50 weight% pTHF component, or at least 60 weight% pTHF component, or at least 70 weight% pTHF component, or at least 80 weight% pTHF component, at least 90 weight% pTHF component, or 100 weight% pTHF component, based upon the total weight of the polyol component.

[0044] The pTHF component is not particularly limited and any known pTHF component may be used.

[0045] The pTHF component may have a weight average molecular weight (as measured by gel permeation chromatography) of from 500 to 10,000 g / mol, or from 500 to 5000 g / mol, or from 500 to 2000 g / mol. For example, pTHFlOOO may be used as the pTHF component.

[0046] The pTHF component may have a hydroxyl number (as measured by ASTM E222-B) of from 10 mg KOH / g to 1000 mg KOH / g, or from 10 mg KOH / g to 500 mg KOH / g, or from 10 to 200 mg KOH / g.

[0047] In one embodiment, the polyurethane-based product is produced from a polytetrahydrofuran component and a methylene diphenyl diisocyanate (MDI)-based polyisocyanate component.

[0048] Additives, such as catalysts, blowing agents, chain extenders and the like may be used in the production of the polyurethane-based foam. Any additives known in the art may be used and are not particularly limited.10 EU-51181

[0049] In one embodiment, the polyurethane-based product is a foam. In one embodiment, the polyurethane-based product is waste product or post-consumer product.

[0050] In one embodiment, the isocyanate index used to produce the polyurethane-based product is from 80 to 400, or from 80 to 350, or from 80 to 200, or from 80 to 150.

[0051] As used herein, the isocyanate index refers to the ratio of isocyanate groups (NCO- groups) over isocyanate-reactive hydrogen atoms present in a composition:[NCO] x 100[active hydrogen]In other words, the isocyanate index expresses the percentage of isocyanate used in a composition with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in the composition. It should be observed that the isocyanate index as used herein is considered from the point of view of the actual polymerisation process preparing the material involving the isocyanate ingredient and the isocyanate-reactive ingredients. Any isocyanate groups consumed in a preliminary step to produce modified polyisocyanates (including such isocyanatederivatives referred to in the art as prepolymers) or any active hydrogens consumed in a preliminary step (e.g. reacted with isocyanate to produce modified polyols or polyamines) are not taken into account in the calculation of the isocyanate index. Only the free isocyanate groups and the free isocyanate-reactive hydrogens (including those of water, if used) present at the actual polymerisation stage are taken into account.

[0052] [Distillation step]

[0053] Step i) removes at least a part of the chemolysis component from the first mixture by distillation to form a second mixture. Preferably, Step i) removes substantially all of the chemolysis component, or at least 99 weight% of the chemolysis component based upon the total weight of chemolysis component in the first mixture, from the first mixture by distillation to form a second mixture. In one embodiment, the second mixture comprises less than 5 weight% of the chemolysis component, or less than 3 weight% of the chemolysis component, or less than 1 weight% of the chemolysis component, based upon 100 weight% of the second mixture. In one embodiment, the distillation step removes or reduces the amount of the chemolysis component only.

[0054] The distillation method is not particularly limited, and any known distillation method may be used. The skilled person knows that an important consideration for distillation temperature is the boiling point of the chemolysis component, and they would suitably11 EU-51181 adjust the distillation process so as to remove the chemolysis component. For example, the distillation temperature may be from 50°C to 250°C, or from 100°C to 200°C.

[0055] The pressure at which the distillation performed may be standard pressure, or the distillation step may be performed under reduced pressure such as below 100 mbar, or below 50 mbar, or below 10 mbar, or substantially 0 mbar.

[0056] [Acidic wash / extraction step]

[0057] Step ii) mixes the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuran-rich phase and an acidic phase, and isolates the polytetrahydrofuran-rich phase.

[0058] As used herein, “split-phase” refers to a system containing two phases. The two phases are immiscible and separate out on standing after the required period of time.

[0059] As used herein, the term “polytetrahydrofuran-rich phase” refers to the phase (of the split-phase) which comprises the higher concentration (higher amount of pTHF per gram of the phase) of pTHF relative to the other phase (acidic phase) of the split-phase. The term “acid phase” may refer to the phase (of the split-phase) which comprises the higher concentration (higher amount of acid per gram of the phase) of acid relative to the other phase (polytetrahydrofuran-rich phase) of the split-phase.

[0060] In one embodiment, the pTHF -rich phase contains more than 50 weight%, or at least 55 weight%, or at least 60 weight%, or at least 65 weight%, or at least 70 weight%, or at least 75 weight%, or at least 80 weight%, or at least 85 weight%, or at least 90 weight%, or at least 95 weight%, of the pTHF component in the split-phase mixture, based upon the total weight of the pTHF component in the split-phase mixture.

[0061] The acid used in the acidic solution is not particularly limited and any acid known to work in extraction may be used. In one embodiment, the acidic solution is an aqueous acidic solution. In one embodiment, the acidic solution comprises mineral acid, organic acid, or a combination thereof. In one embodiment, the mineral acid may be hydrochloric acid, nitric acid, sulfuric acid, phosphonic acid or phosphoric acid. In one embodiment, the organic acid may be a carboxylic acid or a sulfonic acid. In one embodiment, the acidic solution is aqueous hydrochloric acid solution.

[0062] The quantity of acidic solution used in step ii) is not particularly limited, as long as enough acidic solution is used to form a split-phase mixture. In one embodiment, from 1 to 5 parts by weight, or from 1 to 3 parts by weight, of acidic solution is added per 1 part by weight of the second mixture.12 EU-51181

[0063] In one embodiment, the concentration of the acidic solution is from 0.01 to 1 mol / L, or from 0.05 to 0.5 mol / L, or from 0.05 to 0.2 mol / L. In one embodiment, the pH of the acidic solution is between 1 and 7, or between 2 and 5, or between 2 and 4.

[0064] In one embodiment, the mixture of the acidic solution and the second mixture may be heated. The temperature range for heating may be from 40°C to 150°C, or from 50°C to 120°C, or from 50°C to 100°C, or from 60°C to 80°C. The mixture of the acidic solution and the second mixture may be mixed for a time period of from 30 minutes to 4 hours, or from 30 minutes to 2 hours, or from 30 mins to 90 mins. The mixture of the acidic solution and the second mixture may be vigorously stirred. Once the time period for mixing is over, the resultant mixture is cooled to obtain a split phase.

[0065] The pTHF-rich phase is isolated from the split-phase mixture. Conventional means to isolate the pTHF-rich phase may be used, such as by using a separating funnel or by siphoning off the pTHF phase from a container.

[0066] In one embodiment, the isolated pTHF-rich phase is then mixed again with acidic solution to form a split-phase mixture comprising pTHF-rich phase and an acidic phase. The same process as above may be repeated to carry out this step. Thus, in one embodiment, the second mixture is washed with acidic solution and the pTHF-rich phase is isolated, and the isolated pTHF-rich phase is further washed with acidic solution and the pTHF-rich phase is again isolated, and the further isolated pTHF-rich phase is further washed with acidic solution and the pTHF-rich phase is again isolated, i.e. 3 acidic washes are performed.

[0067] [Ion exchange step]

[0068] In step iii), the isolated polytetrahydrofuran-rich phase is mixed with an ion exchange compound to form a third mixture. The ion exchange compound may be a single type of ion exchange compound, or two types of ion exchange compound may be used.

[0069] In one embodiment, the ion exchange compound is a cationic exchange compound and / or an anionic exchange compound. In one embodiment, the ion exchange compound includes a cationic exchange compound and optionally further includes an anionic exchange compound. In one embodiment, the ion exchange compound includes a cationic exchange compound and an anionic exchange compound.

[0070] The purpose of the ion exchange compound is to remove the polyamine component. One way in which this may be achieved is by the ion exchange compound trapping the polyamine component as a salt. In one embodiment, a cationic ion exchange compound is used to remove at least a part of the polyamine component from the pTHF-rich phase.13 EU-51181

[0071] Another purpose of the ion exchange compound may be to neutralise the pTHF-rich phase. In one embodiment, an anionic ion exchange compound is used to neutralise the pTHF-rich phase.

[0072] Any suitable ion exchange compound known in the art may be used in the present disclosure. For example, a suitable cationic exchange compound includes AmberLyst™ 15(H) available from DuPont™, and a suitable anionic exchange compound includes AmberLyst™ A21 available from DuPont™.

[0073] In one embodiment, from 1 to 25 parts by weight, or from 5 to 20 parts by weight, or from 5 to 15 parts by weight, or from 8 to 12 parts by weight, of the ion exchange compound are added to the pTHF-rich phase per 100 parts of the pTHF-rich phase.

[0074] In one embodiment, from 1 to 20 parts by weight, or from 5 to 15 parts by weight, or from 8 to 12 parts by weight, of the cationic exchange compound are added to the pTHF- rich phase per 100 parts of the pTHF-rich phase.

[0075] In one embodiment, from 1 to 10 parts by weight, or from 1 to 5 parts by weight, or from 1 to 3 parts by weight, of the anionic exchange compound are added to the pTHF- rich phase per 100 parts of the pTHF-rich phase.

[0076] If used, the cationic exchange compound and the anionic exchange compound may be added separately or simultaneously.

[0077] In one embodiment, the mixture of the pTHF-rich phase and the ion exchange compound may be heated. The temperature range for heating may be from 40°C to 150°C, or from 50°C to 120°C, or from 50°C to 100°C, or from 60°C to 80°C. The mixture of the pTHF-rich phase and the ion exchange compound may be mixed for a time period of from 30 minutes to 12 hours. The mixture of the pTHF-rich phase and the ion exchange compound may be vigorously stirred.

[0078] [Filtration step]

[0079] In step iv), the third mixture is filtered to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component. The solids which may be removed include the polyamine salts formed in step iii).

[0080] The type of filtration is not particularly limited, and any known method may be used. For example, Buchner filtration may be used.

[0081] In one embodiment, the product mixture comprises at least 95 weight% of pTHF component, or at least 96 weight% of pTHF component, or at least 97 weight% of pTHF component, or at least 98 weight% of pTHF component, or at least 99 weight% of14 EU-51181 polytetrahydrofuran component, or at least 99.5 weight% of polytetrahydrofuran component, based upon the total weight of the product mixture.

[0082] In one embodiment, the product mixture comprises 3.5 weight% or less, or 3 weight% or less, or 2.5 weight% or less, or 2 weight% or less, or 1.5 weight% or less, or 1 weight% or less, or 0.5 weight% or less of polyamine component, based upon the total weight of the product mixture.

[0083] [Recycled polytetrahydrofuran]

[0084] The present disclosure provides a product mixture comprising the polytetrahydrofuran component obtained according to the method as defined herein. The pTHF component may also be called a recycled-pTHF or simply r-pTHF. Moreover, the term “product mixture” may be interchangeably used herein with the term “pTHF component” in the context of the final obtained product mixture / r-pTHF component.

[0085] The OH value of the product mixture (comprising the r-pTHF) is from 70% to 130% of the OH value of the polytetrahydrofuran component used to produce the polyurethane- based foam (i.e., the virgin pTHF). In one embodiment, the OH value of the product mixture is from 75% to 125%, or from 80 % to 120%, or from 85 % to 115%, or from 90% to 110%, or from 95% to 105%, of the OH value of the polytetrahydrofuran component used to produce the polyurethane-based foam (i.e., the virgin pTHF). This indicates excellent recovery of the pTHF component from the polyurethane-based product.

[0086] [Method of preparing a polyurethane-based product]

[0087] The present disclosure provides a method of preparing a polyurethane-based product, comprising mixing a polyisocyanate component and the product mixture comprising the polytetrahydrofuran component as defined herein.

[0088] The polyisocyanate may be as described herein for the polyurethane-based product which was recycled by chemolysis.

[0089] The additives, such as chain extenders, surfactants and blowing agents are not limited and are known by the skilled person. Any additives known in the art may be used, as desired or needed.

[0090] [Non-limiting embodiments]

[0091] In an embodiment of the present disclosure, there is provided a method for recovering a polytetrahydrofuran component from a first mixture comprising the polytetrahydrofuran component, a polyamine component and a chemolysis component, the method comprising the following steps in order:15 EU-51181 i) removing at least a part of the chemolysis component from the first mixture by distillation to form a second mixture; ii) mixing the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuran-rich phase and an acidic phase, and isolating the polytetrahydrofuran-rich phase; iii) mixing the polytetrahydrofuran-rich phase with an ion exchange compound to form a third mixture; and iv) filtering the third mixture to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component, the method further comprising a step a) of obtaining the first mixture, the step a) occurring before step i) and comprising steps al) to a4): al) mixing a polyurethane-based product with a chemolysis component to form a reaction mixture, wherein the chemolysis component is an alkanolamine; a2) heating the reaction mixture to form a product mixture (which is different from the product mixture in step iv)); a3) cooling the product mixture to obtain a split-phase mixture comprising a first mixture and a fourth mixture; and a4) isolating the first mixture.

[0092] In an embodiment of the present disclosure, there is provided a method for recovering a polytetrahydrofuran component from a first mixture comprising the polytetrahydrofuran component, a polyamine component and a chemolysis component, the method comprising the following steps in order: i) removing at least a part of the chemolysis component from the first mixture by distillation to form a second mixture; ii) mixing the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuran-rich phase and an acidic phase, and isolating the polytetrahydrofuran-rich phase; iii) mixing the polytetrahydrofuran-rich phase with an ion exchange compound to form a third mixture; and iv) filtering the third mixture to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component, the method further comprising a step a) of obtaining the first mixture, the step a) occurring before step i) and comprising steps al) to a4):16 EU-51181 al) mixing a polyurethane-based product with a chemolysis component to form a reaction mixture, wherein the chemolysis component is an alkanolamine; a2) heating the reaction mixture to form a product mixture (which is different from the product mixture in step iv)); a3) cooling the product mixture to obtain a split-phase mixture comprising a first mixture and a fourth mixture; and a4) isolating the first mixture, wherein the polyurethane-based product is produced from a polytetrahydrofuran component and a methylene diphenyl diisocyanate (MDI)-based polyisocyanate component.

[0093] In an embodiment of the present disclosure, there is provided a method for recovering a polytetrahydrofuran component from a first mixture comprising the polytetrahydrofuran component, a polyamine component and a chemolysis component, the method comprising the following steps in order: i) removing at least a part of the chemolysis component from the first mixture by distillation to form a second mixture; ii) mixing the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuran-rich phase and an acidic phase, and isolating the polytetrahydrofuran-rich phase; iii) mixing the polytetrahydrofuran-rich phase with an ion exchange compound to form a third mixture; and iv) filtering the third mixture to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component, wherein the ion exchange compound includes a cationic exchange compound.

[0094] [Examples]

[0095] The present disclosure will be described in more detail with reference to the Examples. The present disclosure is not limited to the following Examples.

[0096] The polyurethane elastomer foam used in the chemolysis procedures in Examples 1-3 and Comparative Example 1-3 was made from a formulation comprising MDI-based prepolymer; pTHFlOOO (virgin pTHF having an OHv of 113 mg KOH / g); chain extender; silicone surfactant; and a catalyst. The same polyurethane elastomer foam was used in each example.

[0097] Example 117 EU-51181

[0098] A first mixture comprising a polytetrahydrofuran component, a polyamine component and an aminolysis agent (monoethanolamine; MEA) was obtained by aminolysis of a polytetrahydrofuran-based polyurethane product.

[0099] Aminolysis procedure: 150 parts by weight of monoethanolamine (MEA) and 100 parts by weight of polyurethane elastomer foam particles were introduced into a 2 Litre 4- necked round bottom flask equipped with a mechanical stirrer, a thermocouple, a condenser and a nitrogen flow inlet, and heated to 150°C. After complete dissolution of the foam particles, the mixture was kept stirring under nitrogen for 3 hours at 150°C. The reaction was then cooled down to about 90°C under stirring and discharged into a 2 Litre separatory funnel. A split phase occurred within minutes. Both phases were discharged in separate containers to collect the first mixture and fourth mixture.

[0100] A product mixture comprising a polytetrahydrofuran component (r-pTHF) was recovered from the first mixture as follows:

[0101] Distillation step: Excess MEA was distilled off from 300 grams of the first mixture, under reduced pressure (0 mbar) at 140°C to form a second mixture.

[0102] Acidic wash step: 100 grams of the second mixture was transferred to a round bottom flask, and 2 parts (200 grams) by weight aqueous HC1 solution (0.1 M) were added to the second mixture, which was then vigorously homogenised at 70°C for 1 hour under nitrogen atmosphere. Heating was stopped, the mixture allowed to cool, and then the mixture was transferred to a separating funnel. In the separating funnel, the mixture separated into two phases to form a split-phase mixture comprising a polytetrahydrofuran-rich phase (an organic phase) and an acidic phase (an aqueous phase). The organic phase was separated off, and further washed with the aqueous HC1 solution two further times in an analogous manner, with the polytetrahydrofuran-rich phase (an organic phase) being collected each time.

[0103] Ion-exchange step: The resultant polytetrahydrofuran-rich phase was mixed with 10 weight%, based upon 100 weight% of the resultant polytetrahydrofuran-rich phase, of the cationic exchange compound (DuPont™ AmberLyst™ 15(H)) for 6 hours at 75°C to form a third mixture.

[0104] Filtering step: the third mixture was filtered using a Buchner filter to obtain a product mixture comprising a polytetrahydrofuran component (r-pTHF).

[0105] The product mixture contained 99.8 weight% r-pTHF and 0.2 weight% aromatic amine.The product mixture had a pH of 2-3. The composition of the product mixture is summarised in Table 1.18 EU-51181

[0106] Example 2

[0107] A first mixture comprising a polytetrahydrofuran component, a polyamine component and an aminolysis agent (monoethanolamine; MEA) was obtained by aminolysis of a polytetrahydrofuran-based polyurethane product. The same aminolysis procedure as in Example 1 was performed. A product mixture comprising a polytetrahydrofuran component (r-pTHF) was recovered from the first mixture as follows:

[0108] Distillation step: Excess MEA was distilled off from 300 grams of the first mixture, under reduced pressure (0 mbar) at 140°C to form a second mixture.

[0109] Acidic wash step: 100 grams of the second mixture was transferred to a round bottom flask, and 2 parts (200 grams) by weight aqueous HC1 solution (0.1 M) were added to the second mixture, which was then vigorously homogenised at 70°C for 1 hour under nitrogen atmosphere. Heating was stopped, the mixture allowed to cool, and then the mixture was transferred to a separating funnel. In the separating funnel, the mixture separated into two phases to form a split-phase mixture comprising a polytetrahydrofuran-rich phase (an organic phase) and an acidic phase (an aqueous phase). The organic phase was separated off, and further washed with the aqueous HC1 solution two further times in an analogous manner, with the polytetrahydrofuran-rich phase (an organic phase) being collected each time.

[0110] Ion-exchange step and neutralisation step: The resultant polytetrahydrofuran-rich phase was mixed with 10 weight% cationic exchange compound (DuPont™ AmberLyst™ 15(H)) and 2.5 weight% anionic exchange compound (DuPont™ AmberLyst™ A21) for 6 hours at 75°C to form a third mixture, based upon 100 weight% of the resultant polytetrahydrofuran-rich phase.

[0111] Filtering step: the third mixture was filtered using a Buchner filter to obtain a product mixture comprising a polytetrahydrofuran component (r-pTHF).

[0112] The product mixture comprising a polytetrahydrofuran component (r-pTHF) had an OHv (hydroxyl number, as measured according to ASTM E222-B) of 86 mg KOH / g, which was within ±25% of the OHv of the virgin pTHF polyol. The product mixture contained 99.8 weight% r-pTHF and 0.2 weight% aromatic amine. The product mixture had a pH of 4-5. The composition of the obtained product mixture is summarised inTable 1.

[0113] Example 319 EU-51181

[0114] A first mixture comprising a polytetrahydrofuran component, a poly amine component and a chemolysis agent (diethylene glycol; DEG) was obtained by hydro-glycolysis of a polytetrahydrofuran-based polyurethane product.

[0115] Hydro-glycolysis procedure: 150 parts by weight of diethylene glycol (DEG), 100 parts by weight of polyurethane elastomer foam particles and 0.1 parts by weight of KOH (0.1 wt.% based on polyurethane foam) were initially introduced into a 2 Litre four-neck round bottom flask equipped with a mechanical stirrer, a thermocouple, a condenser and a nitrogen flow inlet, and heated to 200°C. After complete dissolution of the foam particles, the mixture was kept stirring under nitrogen for 3 hours at 200°C. Additional 0.1 parts by weight of KOH (0.1 wt.% based on polyurethane foam) were added to the reactor vessel and deionized water was continuously delivered to the reaction mixture using a HPLC pump at a speed of O. lmL / min. The mixture was kept stirring under nitrogen for additional 4 hours at 200°C. Heating and water supply was then stopped. The reaction was cooled down to about 90°C under stirring and discharged into a 2 Litre separatory funnel. Split phase occurred after 30 min to 1 hour. Both phases were discharged in separate containers to collect the first mixture and another mixture.

[0116] A product mixture comprising a polytetrahydrofuran component (r-pTHF) was recovered from the first mixture as follows:

[0117] Distillation step: Excess DEG was distilled off from 200 grams of the first mixture, under reduced pressure (0 mbar) at 170°C to form a second mixture.

[0118] Acidic wash step: 100 grams of the second mixture was transferred to a round bottom flask, and 2 parts (200 grams) by weight aqueous HC1 solution (0.1 M) were added to the second mixture, which was then vigorously homogenised at 70°C for 1 hour under nitrogen atmosphere. Heating was stopped, the mixture allowed to cool, and then the mixture was transferred to a separating funnel. In the separating funnel, the mixture separated into two phases to form a split-phase mixture comprising a polytetrahydrofuran-rich phase (an organic phase) and an acidic phase (an aqueous phase). The organic phase was separated off, and further washed with the aqueous HC1 solution two further times in an analogous manner, with the polytetrahydrofuran-rich phase (an organic phase) being collected each time.

[0119] Ion-exchange step: The resultant polytetrahydrofuran-rich phase was mixed with 10 weight%, based upon 100 weight% of the resultant polytetrahydrofuran-rich phase, of a cationic exchange compound (DuPont™ AmberLyst™ 15(H)) for 3 hours at 75°C to form a third mixture.20 EU-51181

[0120] Filtering step: the third mixture was filtered using a Buchner filter to obtain a product mixture comprising a polytetrahydrofuran component (r-pTHF).

[0121] The product mixture comprising a polytetrahydrofuran component (r-pTHF) had an OHv (hydroxyl number, as measured according to ASTM E222-B) of 78 mg KOH / g, which was within ±30% of the OHv of the virgin pTHF polyol. The product mixture contained 96.9 weight% r-pTHF and 3.1 weight% aromatic amine. The composition of the obtained product mixture is summarised in Table 1.

[0122] Comparative Example 1

[0123] A first mixture comprising a polytetrahydrofuran component, a poly amine component and an aminolysis agent (monoethanolamine; MEA) was obtained by aminolysis of a polytetrahydrofuran-based polyurethane product. The same aminolysis procedure as in Example 1 was performed. The product mixture comprising a polytetrahydrofuran component (r-pTHF) was recovered from the first mixture as follows:

[0124] Distillation step: Excess MEA was distilled off from 300 grams of the first mixture, under reduced pressure (0 mbar) at 140°C to form a second mixture.

[0125] Acidic wash step: 100 grams of the second mixture was transferred to a round bottom flask, and 2 parts (200 grams) by weight aqueous HC1 solution (0.1 M) were added to the second mixture, which was then vigorously homogenised at 70°C for 1 hour under nitrogen atmosphere. Heating was stopped, the mixture allowed to cool, and then the mixture was transferred to a separating funnel. In the separating funnel, the mixture separated into two phases to form a split-phase mixture comprising a polytetrahydrofuran-rich phase (an organic phase) and an acidic phase (an aqueous phase). The organic phase was separated off, and further washed with the aqueous HC1 solution two further times in an analogous manner, with the polytetrahydrofuran-rich phase (an organic phase) being collected each time. The product mixture (comprising recovered r-pTHF polyol component) was the finally collected polytetrahydrofuran-rich phase.

[0126] The product mixture contained 94.7 weight% r-pTHF and 5.3 weight% aromatic amine. The composition of the obtained product mixture is summarised in Table 1.

[0127] Comparative Example 2

[0128] A first mixture comprising a polytetrahydrofuran component, a polyamine component and an aminolysis agent (monoethanolamine; MEA) was obtained by aminolysis of a polytetrahydrofuran-based polyurethane product. The same aminolysis procedure as in21 EU-51181Example 1 was performed. The product mixture comprising a polytetrahydrofuran component (r-pTHF) was recovered from the first mixture as follows:

[0129] Distillation step: Excess MEA was distilled off from 50 grams of the first mixture, under reduced pressure (0 mbar) at 140°C to form a second mixture.

[0130] Ion-exchange step: 20 grams of the second mixture was mixed with 12 weight%, based upon 100 weight% of the second mixture, of a cationic exchange compound (DuPont™ AmberLyst™ 15(H)) for 6 hours at 75°C to form a third mixture.

[0131] Filtering step: The third mixture was filtered using a Buchner filter to obtain a product mixture.

[0132] The product mixture contained 88.7 weight% r-pTHF, 0.2 weight% MEA, 0.9 weight% other compounds and 10.2 weight% aromatic amine. The composition of the obtained product mixture is summarised in Table 1.

[0133] Comparative Example 3

[0134] A first mixture comprising a polytetrahydrofuran component, a polyamine component and a chemolysis agent (diethylene glycol; DEG) was obtained by hydro-glycolysis of a polytetrahydrofuran-based polyurethane product. The same hydro-glycolysis procedure as in Example 3 was performed. The product mixture comprising a polytetrahydrofuran component (r-pTHF) was recovered from the first mixture as follows:

[0135] Ion-exchange step: 27 grams of the first mixture was mixed with 10 weight%, based upon 100 weight% of the first mixture, of a cationic exchange compound (DuPont™ AmberLyst™ 15(H)) for 3 hours at 75°C to form a second mixture. The mixture was cooled and a one-fold excess of tetrahydrofuran (THF) was added to help separate out the liquid phase.

[0136] Distillation step: Excess DEG and THF was distilled off from the second mixture, under reduced pressure (0 mbar) at 170°C to form a third mixture. The third mixture was the product mixture.

[0137] The product mixture contained 80.2 weight% r-pTHF, 11.6 weight% DEG, 8.0 weight% other compounds and 0.2 weight% aromatic amine. The composition of the obtained product mixture is summarised in Table 1.

[0138] Table 1: compositions of product mixture in weight%, based upon 100 weight% of the product mixture22 EU-51181

[0139] It is clear from the results of Examples 1-3 and Comparative Examples 1-3 that using the method of the present disclosure, specifically a distillation step followed by an acidic wash step followed by an ion exchange step, results in an improved recovery of r-pTHF from the mixture derived from a chemolysis reaction of a pTHF-containing polyurethane. More particularly, the recovery of the r-pTHF from the mixture in Examples 1 and 2 is particularly high, and therefore it is apparent that the method described herein is particularly beneficial for a mixture derived from an aminolysis reaction of a pTHF-containing polyurethane. It is clear from Comparative Examples 1-3 that if the method steps of the present method are not carried out in full and in order, an inferior recovery is the result.

[0140] Production of polyurethane foam from the r-pTHF polyol component of Example 3

[0141] A foam was synthesised from the pTHF polyol component recovered in Example 3. The foam formulation corresponded to the foam formulation used in the examples, except that the virgin pTHFlOOO was substituted by 100% product mixture of Example 3. There was substantially no significant difference in the reactivity and mechanical properties between the foams produced using the virgin pTHF and the r-pTHF.

[0142] All ranges described herein are exemplary in nature and include any and all values in between. The terms “substantially”, “approximately” and “about” used herein are interchangeable and refer to a measurement that includes the stated measurement and any measurements reasonably close to the stated measurement. Measurements that are23 EU-51181 reasonably close to the stated measurement deviate from the stated measurement by a reasonably small amount as understood and readily ascertained by individuals having ordinary skill in the relevant art. Such deviations may be attributable to measurement error, differences in measurement and / or manufacturing equipment calibrations, human error in reading and / or setting measurements, minor adjustments made to optimize performance and / or structural parameters in view of differences in measurement associated with other components, particular implementation scenarios, imprecise adjustment and / or manipulation of objects by a person or machine. In the event it is determined that individuals having ordinary skill in the relevant art would not readily ascertain values for such reasonably small differences, the terms “about” and “approximately” can be understood to mean plus or minus 10% of the stated value.

[0143] Throughout the description and claims, the terms take the meanings explicitly defined herein, unless the context clearly dictates otherwise.

[0144] The phrases “in one embodiment”, “in an embodiment” and “in some embodiments” etc. as used herein do not necessarily refer to the same embodiment s), though they may. Furthermore, the phrases “in another embodiment” and “in some other embodiments” as used herein do not necessarily refer to a different embodiment, though they may. All embodiments of the present disclosure are intended to be combinable.

[0145] The terms “comprises” and “comprising” mean to include but not limited to, such that further features may be present. The terms may also mean to consist of or consist essentially of.

[0146] All references and test methods cited herein are incorporated by reference in their entireties.

Claims

24 EU-51181CLAIMS1. A method for recovering a polytetrahydrofuran component from a first mixture comprising the polytetrahydrofuran component, a poly amine component and a chemolysis component, the method comprising the following steps in order: i) removing at least a part of the chemolysis component from the first mixture by distillation to form a second mixture; ii) mixing the second mixture with an acidic solution to form a split-phase mixture comprising a polytetrahydrofuran-rich phase and an acidic phase, and isolating the polytetrahydrofuran-rich phase; iii) mixing the polytetrahydrofuran-rich phase with an ion exchange compound to form a third mixture; and iv) filtering the third mixture to remove any solids to obtain a product mixture comprising the polytetrahydrofuran component.

2. A method according to Claim 1, further comprising a step a) of obtaining the first mixture, the step a) occurring before step i) and comprising: a) mixing a polyurethane-based product with a chemolysis component to obtain the first mixture, wherein the polyurethane-based product is produced from a polytetrahydrofuran component, preferably wherein the polyurethane-based product is produced from a polytetrahydrofuran component and a methylene diphenyl diisocyanate (MDI)- based polyisocyanate component.

3. A method according to Claim 2, wherein the step a) forms a split-phase mixture comprising a first mixture and a fourth mixture, and wherein step a) further comprises isolating the first mixture.

4. A method according to any preceding claim, wherein the chemolysis component is an aminolysis component, preferably an alkanolamine.

5. A method according to Claim 2, wherein step a) comprises steps al) to a4): al) mixing the polyurethane-based product with a chemolysis component to form a reaction mixture, wherein the chemolysis component is an alkanolamine, preferably wherein the alkanolamine contains a primary or secondary amine group and has a molar mass of about 150 g / mol or less;25 EU-51181 a2) heating the reaction mixture to form a product mixture; a3) cooling the product mixture to obtain a split-phase mixture comprising a first mixture and a fourth mixture; and a4) isolating the first mixture.

6. A method according to Claim 5, wherein the polyurethane-based product is produced from a polytetrahydrofuran component and a methylene diphenyl diisocyanate (MDGbased polyisocyanate component.

7. A method according to any preceding claim, wherein, in step i), substantially all of the chemolysis component is removed from the first mixture to obtain the second mixture, or wherein the second mixture comprises less than 1 weight% of the chemolysis agent based upon 100 weight% of the second mixture.

8. A method according to any preceding claim, wherein, in step ii), the acidic solution is an aqueous acidic solution, preferably an aqueous hydrochloric acid solution.

9. A method according to any preceding claim, wherein in step iii), the ion exchange compound is a cationic exchange compound and / or an anionic exchange compound.

10. A method according to any preceding claim, wherein the OH value of the product mixture is from between 70% to 130% of the OH value of the polytetrahydrofuran component used to produce the polyurethane-based foam.

11. A method according to any preceding claim, wherein the product mixture comprises at least 95 weight% of polytetrahydrofuran component, preferably at least 99 weight% of polytetrahydrofuran component, based upon the total weight of the product mixture.

12. A method according to any preceding claim, wherein the product mixture comprises 3.5 weight% or less of polyamine component, based upon the total weight of the product mixture.

13. A product mixture comprising a polytetrahydrofuran component obtained according to the method as defined in any preceding claim.

14. A method of preparing a polyurethane-based product, comprising mixing a polyisocyanate component and a product mixture comprising the polytetrahydrofuran component as defined in Claim 13.

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