Process for recovering valuable substances from polyurethane foams

Abstract

This invention relates to a method for recovering valuable substances from polyurethane foam, comprising: (A) providing a polyurethane foam based on an isocyanate component and a polyether polyol component; (B) chemically decomposing the polyurethane foam by reacting it with an organic chemical decomposition agent and water, wherein the organic chemical decomposition agent is selected from: (i) a primary or secondary chemically decomposable amine, (ii) a chemically decomposable amino alcohol having a primary or secondary amino group, (iii) a chemically decomposable alcohol, or (iv) a mixture of two or more of the said organic chemical decomposition agents; (C) distilling off the organic chemical decomposition agent and optionally toluene diamine or a portion thereof generated in (B), wherein solid components can be separated before and / or after distillation; (D) extracting the polyether polyol with an organic solvent, wherein an acid and water are added, and a polyol phase is obtained after separation of the acidic aqueous phase; and (E) post-treating the polyol phase to obtain at least one polyether polyol.

Description

[0001] This invention relates to a method for recovering valuable substances from polyurethane foam, comprising: (A) providing a polyurethane foam based on an isocyanate component and a polyether polyol component; (B) chemically decomposing the polyurethane foam by reacting it with an organic chemical decomposition agent and water, wherein the organic chemical decomposition agent is selected from: (i) a primary or secondary chemically decomposable amine, (ii) a chemically decomposable amino alcohol having a primary or secondary amino group, (iii) a chemically decomposable alcohol, or (iv) a mixture of two or more of the said organic chemical decomposition agents; (C) distilling off the organic chemical decomposition agent and optionally toluene diamine or a portion thereof generated in (B), wherein solid components can be separated before and / or after distillation; (D) extracting the polyether polyol with an organic solvent, wherein an acid and water are added, and a polyol phase is obtained after separation of the acidic aqueous phase; and (E) post-treating the polyol phase to obtain at least one polyether polyol.

[0002] Polyurethane foam has a wide range of applications in industry and daily life. Polyurethane foam is generally classified into rigid foam and flexible foam. Despite their diverse types, all these products share a common polyurethane basic structure, formed by the addition polymerization reaction of polyisocyanates and polyols. For example, polyurethane based on diisocyanate O=C=NRN=C=O and diol HO-R'-OH (where R and R' represent organic groups) is used as... ~~~[O-R'-O-(O=C)-HN-R-NH-(C=O)]~~~.

[0003] The enormous economic success of polyurethane products has generated a large amount of polyurethane waste (such as old mattresses or furniture), which must be properly utilized. The simplest technically feasible method of reuse is incineration, which uses the released heat for other processes, such as industrial production. However, this does not achieve a closed-loop cycle of raw materials. Another method of reuse is so-called "physical recycling," in which polyurethane waste is mechanically crushed and used to produce new products. This recycling method naturally has limitations, so efforts have been made to recover the basic raw materials for polyurethane production by re-breaking polyurethane bonds (so-called "chemical recycling"). These recycled raw materials mainly include polyols (HO-R'-OH in the example above). Additionally, amines (H2N-R-NH2 in the example above) can be obtained through the hydrolysis and cracking of urethane bonds, which, after post-treatment, can be phosgenated to produce isocyanates (O=C=NRN=C=O in the example above). Simón, Borreguero, Lucas, and Rodríguez summarized known polyurethane recycling methods in their review article in Waste Management 2018, 76, 147–171 [1]. Diol hydrolysis (see point 2 below) is particularly important here.

[0004] Various chemical recycling methods have been developed in the past. Five of these methods are briefly summarized below: 1. The urethane is hydrolyzed by reacting with water to obtain amines and polyols, which in turn form carbon dioxide.

[0005] 2. Diollysis (alcohololysis) of urethanes is achieved through reaction with an alcohol, in which the polyol incorporated into the urethane group is replaced by the alcohol used and thus released. This method is commonly referred to in the literature as transesterification (more precisely: urethane transesterification). Regardless of the exact nature of the alcohol used, this chemical recycling method is generally referred to in the literature as diollysis—although this term actually applies only to diols and should therefore be more broadly called alcohollysis. Hydrolysis can be carried out after diollysis. If hydrolysis is carried out in the presence of the unaltered diollysis mixture (i.e., without prior separation of the formed polyol), this is called... 3. Hydrolysis of urethane bonds (hydroethanololysis). Alternatively, alcohol and water can be added from the outset, in which the hydrolysis and diololysis processes described above occur in parallel.

[0006] 4. The urethane bond undergoes ammonolysis via reaction with a primary or secondary amine, in which the polyol incorporated into the urethane group can be replaced by the amine used and thus released. At this point, the urethane group is converted to a urea group. Similarly, the R-NH-(C=O)- bond in the urethane can be cleaved, and the R-NH- group can be replaced by the amine used in the ammonolysis, thereby releasing the amine R-NH2 corresponding to the originally used isocyanate. If an amino alcohol with a primary or secondary amino group is used, the alcohol group of the amino alcohol used can of course also react with the urethane bond to form a carbamate. According to the teachings of most existing technologies, hydrolysis can be carried out in a separate step after ammonolysis.

[0007] 5. WO 2023 / 083968 A1 describes the reaction mechanism corresponding to hydrodiol hydrolysis, in which amines or amino alcohols and water are used as reagents without prior separation of the released polyol (see below), and is referred to therein as amino hydrolysis.

[0008] EP 0 013 350 A1 describes a method for separating chemically decomposed products obtained by polyurethane hydrolysis (in accordance with the teachings of publication DE 2 442 387, i.e., at 100°C to 300°C and 5 bar to 100 bar) into polyols or polyamines that can be reused in the preparation of polyurethane plastics, wherein hydrogen chloride gas is introduced into the hydrolysate mixture, preferably diluted with an inert solvent, particularly toluene, and the formed amine salts are filtered off, wherein the hydrogen chloride precipitate is fractionated (in several sub-steps).

[0009] DE 2 207 379 discloses a method for recovering polyether polyols from polyurethane plastics, wherein pulverized plastic is subjected to pressure in an autoclave at approximately 20 atmospheres (overpressure) (19.6 bar). (超压) The reaction product is heated to 150 to 220°C under direct vapor pressure for at least 1 hour. For post-treatment, the treated reaction product can be dissolved in an organic solvent, such as toluene, with the addition of dilute hydrochloric acid and then filtered. The remaining organic solution is evaporated and filtered to obtain the polyether polyol residue.

[0010] US 3,404,103 describes a method for decomposing polyurethanes based on polyether polyols with amines in the presence of an alkaline catalyst, such as an oxide or hydroxide of an alkali metal or alkaline earth metal. Here, the urethane and urea bonds in the polyurethane are converted to ureas for chemical decomposition, thereby releasing the polyether polyol. These ureas are then cleaved under the influence of an alkaline catalyst into amines (i.e., the amines corresponding to the isocyanates used in the synthesis of the polyurethane, and the amines for chemical decomposition) and carbonates (e.g., sodium carbonate). When ethanolamine (2-aminoethanol, also known as monoethanolamine) is used, 2-oxazolidinone is formed as an intermediate. This intermediate is cleaved under the influence of an alkaline catalyst into ethanolamine and carbonates.

[0011] EP 0 990 674 B1 describes a two-step chemical decomposition method in which polyurethane starting material, particularly foam (flexible or rigid foam, preferably flexible foam), is dissolved in a first stage by adding a glycol, polyamine, or amino alcohol at 120°C to 250°C, and then optionally after filtration to separate the solids, is dissolved in water in an autoclave at 200°C to 320°C and 49 to 76 bar in a second stage. (超压) (50 to 78 kg / cm) 2 Hydrolysis was performed under pressure (see Example G). For post-processing, water was extracted in gaseous form, distilled, or purged with an inert gas. The solvent was removed by distillation. The resulting polyols and polyamines were separated by distillation, centrifugation, or solvent extraction. The amine-containing hydrolysate could also react with alkyl epoxides to produce polyols.

[0012] EP 1 142 945 A2 describes a method in which a polyamine is first added to a polyurethane starting material, particularly polyurethane foam (flexible or rigid foam, preferably flexible foam), and heated to 120°C to 250°C. This forms a liquid phase containing a polyol and a dissolved polyurea portion, and a solid phase containing an undissolved polyurea portion. The liquid phase is then hydrolyzed in an autoclave at a temperature of 200 to 320°C and under high pressure (at least 4.7 MPa = 47 bar in the examples). The solid phase may dissolve in more polyamine and is then optionally hydrolyzed similarly after the undissolved portion is separated. For post-treatment, water is extracted in gaseous form, distilled off, or purged with an inert gas. The solvent is removed by distillation. The resulting polyol and polyamine are separated by distillation, centrifugation, or solvent extraction. The amine-containing hydrolysate may also react with alkyl epoxides to generate polyols. Although the specification mentions that this method can also be used for rigid foams. However, its isocyanate component typically comprises methylene diphenyl diisocyanate (mMDI, containing two isocyanate groups) and polymethylene polyphenyl polyisocyanate (pMDI, containing three or more isocyanate groups—a mixture of mMDI and pMDI hereinafter referred to as MDI). The amine corresponding to pMDI (polymethylene polyphenyl polyamine, pMDA) formed during chemical decomposition cannot be distilled without decomposition. Practical methods for recovering such amines have not yet been disclosed.

[0013] EP 1 149 862 A1 describes a method in which rigid foam is dissolved in an amine or glycol at 100°C to 250°C and at atmospheric pressure, followed by hydrolysis. Suitable polyurethane foams disclosed are based on toluene diisocyanate (TDI) and / or methylene diphenyl diisocyanate (mMDI). Hydrolysis is carried out using supercritical or subcritical water. The disclosed hydrolysis pressure ranges from 100 to 250 bar. Post-treatment is accomplished by fractionation. The recovered amine can be used for the new production of isocyanates or as a starting agent for polyol synthesis.

[0014] Patent application CN 116 041 191 A claims a method for "extracting" toluene diamine (TDA) from the "alcoholization products" of flexible polyurethane foam, which includes the following steps: ● The mixture of TDA and the alcoholysis reagent (e.g., diethylene glycol) used is separated by vacuum distillation; ● A mixture of TDA and alcoholysis reagent is reacted with carboxylic acid acyl chloride, in which TDA amide salt is precipitated and separated by filtration; ● The remaining alcoholysis reagent after filtration is purged with nitrogen stripping to remove hydrogen chloride, and the purge gas stream is introduced into water to generate hydrochloric acid; and ● TDA amide salt is dissolved in hydrochloric acid and phase separation is performed to produce an organic phase containing carboxylic acid acyl chloride and an aqueous phase containing TDA.

[0015] Although the application repeatedly mentions "alcohololysis," the context clearly indicates that it refers to aqueous alcohololysis, otherwise the "alcohololysis products" would necessarily contain a large proportion of carbamates of the alcohololysis reagent and TDI, not TDA. In any case, the multi-step process of generating amide salts using organic acyl chlorides and recovering TDA and acyl chlorides is quite complex.

[0016] Patent application CN 115 785 520 A claims a method for extracting polyether polyols from the "alcoholization products" of flexible polyurethane foam, which includes the following steps: ● Acidify the "alcohololysis product" with an inorganic acid to obtain a moderately acidic emulsion; ● The emulsion is broken and the formed phase is separated by adding a demulsifier, particularly polyoxyethylene-polyoxypropylene-alkyl alcohol (wherein the degree of polymerization of ethylene oxide is preferably 6 to 10, the degree of polymerization of propylene oxide is preferably 10 to 15, and the chain length of the alkyl alcohol is preferably 12 to 18 carbon atoms). ● Extract the polyether polyol from the resulting organic phase using a polar solvent.

[0017] This application consistently refers to "alcohololysis," although all specifically disclosed alcoholysis product compositions contain a large proportion of TDA and no carbamates are detected, meaning this must be hydrolysis. In any case, it is disadvantageous to use demulsifiers with relatively high molecular weights that are therefore difficult or impossible to distill.

[0018] Patent application WO 2023 / 099420 A1 describes a method for recovering at least one raw material from a polyurethane product, the method comprising the steps of: (A) providing a polyurethane product based on an isocyanate component and a polyol component, wherein the isocyanate component contains only its corresponding amine at 1013 mbar. (绝对)(A) An isocyanate with a boiling point of up to 410°C, preferably between 170°C and 400°C; (B) Chemical decomposition of the polyurethane product with alcohol and water; (C) Post-treatment of the chemical decomposition product, including (CI) using at a temperature of 10°C to 60°C at 1013 mbar. (绝对) Extraction is performed using an organic solvent with a lower boiling point of 40°C to 120°C, followed by (C.II) phase separation into a first product phase and a second product phase, and (D) post-treatment of the first product phase to obtain a polyol, including (DI) separation of the organic solvent by distillation and / or stripping, and (D.II) separation of the amine dissolved in the first product phase by distillation to obtain the polyol.

[0019] Patent application WO 2023 / 083968 A1 describes a method for recovering raw materials from polyurethane products, particularly polyurethane foam, comprising chemical decomposition. The chemical decomposition is characterized by reacting the polyurethane product with (i) an amine chemical decomposition agent and (ii) water in the presence of (iii) a catalyst at a temperature of 100°C to 195°C and 900 mbar. (绝对) Up to 2000 millibars (绝对) The reaction is carried out under pressure, wherein the amine chemical decomposition reagent is selected from: (a) primary or secondary organic amines; (b) amino alcohols having primary or secondary amino groups; or (c) a mixture of (a) and (b); wherein the mass ratio of the amine chemical decomposition reagent and water to the polyurethane product of the other side is 0.5 to 2.5, and the mass of water is 3.0% to 22% of the mass of the amine chemical decomposition reagent. For TDI-based polyurethane foams, post-treatment of the chemical decomposition products is preferably carried out by extraction with an extractant comprising (i) an organic solvent selected from (aliphatic or aromatic) hydrocarbons or halogen-substituted, particularly chlorinated (aliphatic or aromatic) hydrocarbons and (ii) water; then phase separation is performed to form a first product phase (an aqueous phase of TDA containing the amine chemical decomposition reagent) and a second product phase (a polyol-solvent phase). The valuable substances TDA and polyols are preferably obtained from these two phases by distillation and / or stripping.

[0020] Of the known chemical recycling processes, only a few have achieved continuous operation at an industrial scale; many have not even reached pilot-scale operation in one go [1]. Given the growing environmental awareness and increasing efforts to make industrial processes as sustainable as possible—both of which are essentially called chemical recycling—it is clear that chemical recycling of polyurethane products is far from mature from a technical and economic perspective. There are many challenges, especially in terms of the purity of the recycled products. In addition, economically efficient recycling methods must ensure that the reagents used (e.g., alcohols, amino alcohols, or amines) can be recovered and reused as completely as possible (circular operation). Polyurethane foam recycling is particularly important because it generates large volumes of polyurethane waste (e.g., refrigerators, hot water tanks, mattresses, chair furniture, car seats, etc.). Furthermore, the polyurethane products to be reused usually still contain various additives and auxiliaries (stabilizers, catalysts, etc.), which must be separated from and disposed of in an economically feasible and environmentally friendly manner from the actual recycling target products.

[0021] The aforementioned reuse process can still be improved. A particular challenge remains in achieving the most complete separation of the polyols and amines. This is especially important for products produced in very large quantities, such as polyurethane foams based on TDI and polyether polyols.

[0022] Therefore, further improvements are needed in the field of chemical recycling of polyurethane foam. In view of this need, the subject of this invention is a method for recovering valuable substances from polyurethane foam, comprising the following steps: (A) Provides a polyurethane foam, particularly a flexible foam, based on an isocyanate component and a polyol component, wherein the isocyanate component comprises toluene diisocyanate, particularly excluding other isocyanates different from toluene diisocyanate (e.g., methylene diphenyl diisocyanate and / or polymethylene polyphenyl polyisocyanate) (i.e., particularly composed of toluene diisocyanate), and wherein the polyol component comprises (at least one) polyether polyol, particularly excluding other polyols different from polyether polyols (e.g., polyester polyol) (i.e., particularly composed of (at least one) polyether polyol); (B) Polyurethane foam undergoes chemical decomposition through reaction with organic chemical decomposition agents and water. The organic chemical decomposition reagent is selected from: (i) primary or secondary chemical decomposition amines, (ii) chemical decomposition amino alcohols having primary or secondary amino groups, (iii) chemical decomposition alcohols, or (iv) mixtures of two or more of the organic chemical decomposition reagents, wherein (iii) is preferred. To obtain a chemical decomposition product comprising (at least one) polyether polyol, toluene diamine and an organic chemical decomposition agent (the organic chemical decomposition agent is released again by the hydrolytic cleavage of urethane and / or urea formed as intermediates of toluene diisocyanate and the organic chemical decomposition agent); (C) Distilling the organic chemical decomposition reagent and optionally toluene diamine or a portion thereof from the chemical decomposition products to obtain a chemical decomposition product with depleted organic chemical decomposition reagent (and optionally toluene diamine), wherein solid components can be separated before and / or after distillation; (D) Extraction of said (at least one) polyether polyol from the chemical decomposition products of a depleted organic chemical decomposition reagent (and optionally toluene diamine and optionally solid components) using, in particular, a halogenated organic solvent. Acid and water are added (the order in which the organic solvent, acid, and water, especially halogenated ones, are added is variable). In particular, this allows for the addition of an aqueous acid (and optionally more water) (the order in which the particularly halogenated organic solvent, the aqueous acid, and optionally more water are added can vary). And after separating the acidic aqueous phase, a polyol phase containing the (especially halogenated) organic solvent and the (at least one) polyether polyol is obtained; and (E) Post-treatment of the polyol phase to obtain the (at least one) polyether polyol.

[0023] Completely unexpectedly, it was found that adding acid and water (preferably in the form of an aqueous acid and optionally more water) during the extraction step improved the separation of polyether polyols and toluene diamine. Toluene diamine is soluble in both polar organic solvents and water (unlike methylenediphenylene diamine), and therefore does not necessarily require protonation for transfer to the aqueous phase. However, the protonation of toluene diamine resulted in its almost quantitative transfer to the aqueous phase, which was unexpected.

[0024] In the terminology of this invention, the term "polyol" encompasses all polyols known in the field of polyurethane chemistry. Of course, the term "polyol" also covers embodiments in which two or more different polyols are used in the production of polyurethane foam. Therefore, if "polyether polyol" is mentioned below, this term naturally also covers embodiments in which two or more different polyether polyols are used in the production of polyurethane foam. For the sake of simplicity, this is not necessarily specifically stated below, but is considered to be included unless explicitly stated otherwise. All polyols used in the production of polyurethane foam are collectively referred to as the (polyurethane foam) polyol component. A polyol component contains at least one polyol. If a polyol component contains exactly one (1) polyol, then that polyol is a polyether polyol.

[0025] In the terminology of this invention, the term "isocyanate" encompasses all isocyanates known in the field of polyurethane chemistry. The term "isocyanate" also naturally encompasses embodiments in polyurethane foam production that use two or more different isocyanates (e.g., a mixture of MDI and TDI), unless otherwise explicitly stated, such as using the expression "exactly one isocyanate." All isocyanates used in the production of polyurethane foam are collectively referred to as the isocyanate component (of the polyurethane foam). The isocyanate component contains at least one isocyanate.

[0026] The amine corresponding to isocyanate refers to the amine that can be used according to R-NH 2 + COCl 2 →RN=C=O + 2 HCl Amines of isocyanates are obtained by phosgenation.

[0027] Adding "acid and water" in step (D) can be achieved by adding an aqueous acid (i.e., an acid solution in water). In this case, more water can be added (i.e., in addition to the water content of the aqueous acid), but it is not necessary.

[0028] First, a brief overview of the various possible implementations of the present invention: In a first embodiment of the invention (which may be combined with all other embodiments), the (at least one) polyether polyol comprises (at least one) polyether polyol filled with a polymer, wherein the polymer comprises (at least one) a polymer containing a vinyl monomer, a polyurea, and / or a polyurethane.

[0029] In a second embodiment of the invention (a special configuration of the first embodiment), the polymer comprises (at least one) a polymer containing a vinyl monomer, particularly such a polymer containing at least one vinyl monomer.

[0030] In a third embodiment of the invention (a special configuration of the second embodiment), the (at least one) vinyl monomer-containing polymer comprises a styrene-acrylonitrile copolymer, particularly such a styrene-acrylonitrile copolymer.

[0031] In the fourth embodiment of the present invention (a special configuration of the first to third embodiments), the (at least one) polyether polyol contains no other polyether polyols except for (at least one) polyether polyols filled with polymer.

[0032] In a fifth embodiment of the invention (which can be combined with all other embodiments), the polyol component contains no other polyols different from polyether polyols, except for (at least one and optionally filled with a polymer) polyether polyols.

[0033] In a sixth embodiment of the invention (which can be combined with all other embodiments), the isocyanate component includes, in addition to toluene diisocyanate, methylene diphenyl diisocyanate or a mixture of methylene diphenyl diisocyanate and polymethylene polyphenyl polyisocyanate, particularly those having a high proportion of methylene diphenyl diisocyanate.

[0034] In the seventh embodiment of the present invention (which can be combined with all other embodiments), the isocyanate component contains no other isocyanates except toluene diisocyanate.

[0035] In the eighth embodiment of the present invention (a special configuration of the sixth embodiment), the isocyanate component comprises polyisocyanurate.

[0036] In the ninth embodiment of the present invention (a special configuration of the sixth to eighth embodiments), the isocyanate component comprises a prepolymer of the isocyanate (i.e., toluene diisocyanate, polymethylene polyphenylene polyisocyanate and / or methylene diphenylene diisocyanate) and a polyol.

[0037] In the tenth embodiment of the present invention (which can be combined with all other embodiments), (i) The primary or secondary chemically decomposed amines comprise aliphatic primary or secondary organic amines, particularly 1,2-ethylenediamine, 1,4-diaminobutane and / or 1,6-hexanediamine; (ii) Chemically decomposed amino alcohols include aliphatic amino alcohols having primary or secondary amino groups, particularly ethanolamine, N-methylethanolamine and / or 3-amino-1-propanol; and / or (iii) Chemically decomposed alcohols include methanol, ethanol, propanol (all isomers, preferably n-propanol), butanol (all isomers, preferably n-butanol), isopropanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl ethylene glycol, triethylene glycol, glycerol, 2-methylpropane-1,3-diol, or mixtures of two or more of the alcohols mentioned above.

[0038] In the eleventh embodiment of the present invention (which may be combined with all other embodiments), the mass ratio of the organic chemical decomposition reagent and water on one side (1) to the polyurethane foam on the other side (2) (m(1) / m(2); i.e. [m(organic chemical decomposition reagent) + m(water)] / m(polyurethane product); where m represents mass) is 0.5 to 2.5, wherein the mass of water is 3.0% to 22% of the mass of the chemical decomposition reagent.

[0039] In the twelfth embodiment of the invention (which can be combined with all other embodiments), step (B) is performed at a temperature of 100°C to 195°C, preferably 110°C to 190°C, more preferably 115°C to 160°C, and 900 mbar. (绝对) Up to 2000 millibars(绝对) 950 millibars is preferred (绝对) Up to 1500 millibars (绝对) More preferably 1000 millibars (绝对) Up to 1300 millibars (绝对) The process is carried out under pressure, especially at atmospheric pressure, with reflux cooling used when necessary.

[0040] In the thirteenth embodiment of the invention (which can be combined with all other embodiments), in step (B) the polyurethane foam is... (II) First add (1) the organic chemical decomposition reagent but before adding water, or add (2) the organic chemical decomposition reagent and the water from the first part, then (II) Add water (1) or water (2) from the second part.

[0041] In the fourteenth embodiment of the present invention (a special configuration of the thirteenth embodiment), in step (II), water (1) or a second portion of water (2) is added continuously or in batches, such that the temperature of the liquid phase during step (II) differs from the temperature of the liquid phase in step (I) by a maximum of 20°C, preferably a maximum of 15°C, more preferably a maximum of 10°C, more preferably a maximum of 5.0°C, and most preferably a maximum of 1.0°C.

[0042] In the fifteenth embodiment of the invention (a special configuration of the thirteenth and fourteenth embodiments), the water in the first part of (I) and (2) is at most 4.0% of the total mass of water added in step (B) (i.e., together in (I) and (II), particularly 2.0% to 4.0%).

[0043] In a sixteenth embodiment of the invention (which may be combined with all other embodiments), the organic solvent comprises an aromatic hydrocarbon, a water-insoluble ether, a halogenated (aliphatic or aromatic) hydrocarbon, or a mixture of two or more of the solvents described herein.

[0044] In the seventeenth embodiment of the invention (which can be combined with all other embodiments), the extraction in step (D) is carried out at 10°C to 80°C, preferably 20°C to 60°C.

[0045] In the eighteenth embodiment of the invention (which may be combined with all other embodiments), in step (D), the ratio of the mass m(3) of the chemical decomposition product of the depleted organic chemical decomposition reagent (and optionally toluene diamine and / or other amines and optionally solid components) to the mass m(4) of the organic solvent present in the extractant is m(3) / m(4) = The concentration of the extractant (where m is mass) is 0.03 to 3.0, preferably 0.04 to 2.8, more preferably 0.10 to 2.0, wherein the extractant (total used) comprises 20% to 80% by mass of organic solvent and 20% to 80% by mass of aqueous components. The term "aqueous components" refers to the sum of all aqueous components, i.e., in the preferred embodiment by adding an acid in the form of an aqueous acid, it refers to the sum of the aqueous acid and optionally added additional water.

[0046] In the nineteenth embodiment of the invention (which can be combined with all other embodiments), acid and water are added in step (D) to achieve a pH value of 0.0 to 5.0, particularly 2.5 to 5.0, preferably 3.0 to 4.5, and more preferably 3.7 to 4.2.

[0047] In a twentieth embodiment of the invention (which may be combined with all other embodiments), step (E) includes distillation and / or stripping.

[0048] In the twenty-first embodiment of the invention (which may be combined with all other embodiments), the (at least one) polyether polyol obtained in step (E) reacts with isocyanate to generate polyurethane, particularly polyurethane foam.

[0049] In the twenty-second embodiment of the present invention (which can be combined with all other embodiments), the method includes (F) Post-treatment of the acidic aqueous phase to obtain toluene diamine (and optionally other amines present, corresponding to other isocyanates in the isocyanate component that are different from toluene diisocyanate).

[0050] In the twenty-third embodiment of the invention (a special configuration of the twenty-second embodiment), the post-treatment of the acidic aqueous phase includes neutralization with alkali (optionally "excessive"), followed by phase separation and / or distillation and / or stripping.

[0051] In the twenty-fourth embodiment of the present invention (which can be combined with all other embodiments except the embodiment in which toluene diamine is completely isolated in step (C), toluene diamine is also partially distilled from the chemical decomposition products in step (C).

[0052] In the twenty-fifth embodiment of the present invention (which can be combined with all other embodiments except those that specify that toluenediamine is only partially separated in step (C), toluenediamine is also (completely) distilled from the chemical decomposition products in step (C).

[0053] In the twenty-sixth embodiment of the invention (a special configuration of the twenty-second to twenty-fifth embodiments), the toluene diamine obtained in step (F) (and optionally other amines optionally obtained in step (F), which correspond to isocyanates different from toluene diisocyanate in the isocyanate component) and / or the toluene diamine distilled in step (C) are optionally used, after purification, to prepare toluene diisocyanate (or to prepare other isocyanates in the isocyanate component).

[0054] In the twenty-seventh embodiment of the present invention (a special configuration of the twenty-sixth embodiment), toluene diisocyanate reacts with a polyol to generate polyurethane, particularly polyurethane foam.

[0055] In the twenty-eighth embodiment of the present invention (a special configuration of the twenty-seventh embodiment), the polyol includes the polyether polyol obtained in step (E).

[0056] In the twenty-ninth embodiment of the invention (which can be combined with all other embodiments), the chemical decomposition is carried out in the presence of a catalyst.

[0057] In the thirtieth embodiment of the invention (a special configuration of the twenty-ninth embodiment), the catalyst is selected from hydroxides (especially alkali metal or alkaline earth metal hydroxides), carboxylates (especially acetates) (especially alkali metal or alkaline earth metal carboxylates (especially acetates)), tin compounds (especially dibutyltin dilaurate or tin(II) octoate [= 2-ethylhexanoate tin(II)]), zinc compounds (especially zinc acetate), carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrophosphophosphates (especially alkali metal or alkaline earth metal monohydrophosphophosphates), metaphosphates (especially alkali metal or alkaline earth metal metaphosphates), or mixtures of two or more of the catalysts described above. The catalyst is preferably selected from carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrophosphophosphates (especially alkali metal or alkaline earth metal monohydrophosphophosphates), or mixtures of two or more of the catalysts described above.

[0058] In the thirty-first embodiment of the invention (a special configuration of the twenty-ninth and thirtieth embodiments), the mass ratio of catalyst to polyurethane foam is 0.001 to 0.035.

[0059] In the thirty-second embodiment of the invention (which can be combined with all other embodiments), the organic chemical decomposition reagent distilled in step (C) is optionally returned to step (B) after purification.

[0060] In the thirty-third embodiment of the invention (which may be combined with all other embodiments), the (at least one) polyether polyol contains a molar ratio (as described in the "Foam Analysis" section). 13 (Determined by C-NMR spectroscopy) >45%, especially 46% to 100%, preferably 80% to 100% secondary OH end groups.

[0061] In the thirty-fourth embodiment of the invention (which can be combined with all other embodiments), the acid is selected from hydrogen chloride gas, hydrochloric acid, sulfuric acid, phosphoric acid, sulfonic acid (especially p-toluenesulfonic acid and / or methanesulfonic acid), carboxylic acid (especially trifluoroacetic acid, oxalic acid, formic acid and / or acetic acid, wherein formic acid and acetic acid are preferred) or a mixture of two or more of the acids.

[0062] The embodiments briefly outlined above, as well as other possible configurations of the invention, will be described in more detail below. Unless it becomes obvious from the context to those skilled in the art, or unless otherwise explicitly stated, all the embodiments described above, as well as other configurations of the invention described below, can be combined with each other as needed.

[0063] Provide polyurethane foam for chemical decomposition In step (A) of the method of the present invention, polyurethane foam to be reused through chemical decomposition is provided. According to the invention, the isocyanate component used to produce the polyurethane foam contains at least toluene diisocyanate, and the polyol component contains at least one polyether polyol. In principle, the polyurethane foam can be of various types, provided these conditions are met. Soft or rigid foams are particularly conceivable, with soft foams (e.g., from old mattresses, furniture cushions, or car seats) being preferred.

[0064] The method of this invention can be used for both the reuse of waste (i.e., end-of-life) polyurethane foam and for foam waste generated during foam production. In the latter case, the chemical properties of the isocyanate and polyol components used in the production process are, of course, known.

[0065] For the reuse of waste polyurethane foam, proper sorting is crucial to ensure that it is suitable for the methods of this invention. This is because if the original application of the waste polyurethane foam to be reused is known, it is usually known whether it is a TDI- and polyether-based polyurethane foam. The same applies to other properties of the polyol and isocyanate components used in the production of polyurethane foam, as mentioned below. Therefore, by collecting different foam types separately, it is easy to ensure the identification of suitable foam. If the properties of the existing polyurethane foam are not accurately known (e.g., because it is waste polyurethane foam of an uncertain origin), they can be determined according to the methods described in the "Foam Analysis" section. In particular, this can be achieved through… 1¹H-NMR spectroscopy is used to identify TDI-based polyurethane foams. The chemical properties of the polyol components can be determined by IR spectroscopy.

[0066] According to the present invention, the polyol component comprises at least one polyether polyol. Preferably, the polyether polyol is a "non-reactive" polyether polyol. Here, a "non-reactive" polyether polyol refers to a polyether polyol having a significant molar proportion of secondary OH-terminated groups, the molar proportion of which (as described in the "Foam Analysis" section) 13 The percentage of C-NMR spectroscopy determination is greater than 45%, preferably 46% to 100%, and more preferably 80% to 100%.

[0067] As previously described, in one embodiment of the method of the present invention, the polyol component comprises at least one polymer-filled polyether polyol (PMPO), wherein the polymer comprises at least one vinyl monomer-containing polymer, polyurea, and / or polyurethane. In this case, it is particularly preferred that the polymer comprises at least one vinyl monomer-containing polymer, especially such polymers. Here, the vinyl monomer-containing polymer particularly comprises (preferably) styrene-acrylonitrile copolymer (SAN copolymer). In one embodiment of the method of the present invention, no other polyether polyols are present besides the polymer-filled polyether polyol. Polymer swelling is prevented by distilling off the organic chemical decomposition reagent according to the present invention.

[0068] Optional separation of solid components before and / or after step (C) may include, in particular, the separation of such polymers. Preferably, solid components are separated at least after step (C). It may also be necessary to separate solids twice: a first separation before step (C) to separate most of the solid components, and a second separation after step (C) to separate any remaining residues. In addition to the polymers described above, solid separation may also include the separation of other solid components, such as catalysts used in chemical decomposition or solid components from waste (i.e., end-of-life) polyurethane foam. Such solid components may be, for example, inorganic fillers (e.g., calcium carbonate, barium sulfate, aluminum trihydrate, silicates), flame retardants (e.g., melamine, ammonium polyphosphate), or colorants (e.g., pigments, carbon black). Solid separation prevents entrained solids from causing problems in subsequent process steps, such as the formation of solid deposits on equipment such as pumps or evaporators.

[0069] Regardless of whether the polyol component contains a polymer-filled polyether polyol, the polyol component preferably does not contain any other polyols different from the polyether polyol. More preferably, all polyether polyols are non-reactive polyether polyols as described above.

[0070] The polyether polyols upon which the polyurethane foam to be reused according to the present invention is based typically have the following number-average molar mass and functionality in industrial practice: Number-average molar mass: 2000 g / mol to 8000 g / mol, especially 2500 g / mol to 6500 g / mol, and Functionality: 2 to 8, especially 3 to 6.

[0071] These values ​​can also be achieved in this invention. However, the method of this invention can also utilize polyol-based polyurethane foams, whose properties may differ from the values ​​described above.

[0072] Regarding the isocyanate component of the polyurethane foam, in one embodiment of the method of the present invention, it is specified that, in addition to toluene diisocyanate (TDI), it also comprises (i) methylene diphenyl diisocyanate (mMDI) or (ii) a mixture (MDI) of methylene diphenyl diisocyanate (mMDI) and polymethylene polyphenyl polyisocyanate (pMDI), particularly those having a high proportion of methylene diphenyl diisocyanate (mMDI). In particular, in this embodiment, the polyurethane foam may also comprise polyisocyanurate.

[0073] More preferably, TDI is the only isocyanate in the isocyanate component.

[0074] In the production process of polyurethane foam, the prepolymers of isocyanate and polyol mentioned above can also be used.

[0075] Foam Analysis First, the functional groups of the polyurethane foam (PU) to be analyzed were studied using ATR infrared spectroscopy (ATR = Attenuated Total Reflectance). Infrared spectroscopy (IR spectroscopy) provides the qualitative composition of the polyurethane foam. This allows determination of whether the polyurethane foam is based on polyether polyols and / or polyester polyols. All polyether polyurethanes are characterized by their 1100 cm⁻¹... -1 The COC vibration band at that location. If propylene oxide polyether is present, then at 2960 cm⁻¹. -1 Its typical CH3 valence vibration band appears at this point. IR spectroscopy also provides information about what filler (e.g., calcium carbonate, silicates, SAN polymers) is optionally present. For example, SAN polymers can be observed through approximately 2240 cm⁻¹. -1 The nitrile absorption band at approximately 705 cm⁻¹ -1 The styrene absorption band at 1410 cm⁻¹ is used for identification. IR spectroscopy also provides information on whether it is a partially or fully MDI-based polyurethane foam, as such polyurethane foams can be identified through the styrene absorption band at 1410 cm⁻¹. -1 1010 cm -1 and 510 cm -1Identification is performed using characteristic absorption bands at the site. Partially or entirely TDI-based polyurethane foams are identified after chemical decomposition of the polyurethane foam (see below) via... 1 The methyl groups of the TDA produced by cleavage (measured in CDCl3; chemical shift relative to the residual proton signal) were approximately 2.10 ppm in the 2,4-isomer and approximately 1.97 ppm in the 2,6-isomer. The aromatic range of 2,4-TDA was 6.0 ppm to 7.0 ppm, and that of 2,6-TDA was 6.2 ppm to 7.0 ppm.

[0076] Then, the polyurethane foam is extracted in a Soxhlet extractor for 4 hours under reflux (the boiling point of acetone) with acetone as solvent (S) at a solvent:PU mass ratio of 130:1 to separate low molecular weight additives used in PU production, such as flame retardants and antioxidants.

[0077] To comprehensively study the composition of polyether polyols, complete chemical decomposition of the polyurethane foam from which coexisting substances have been removed is necessary. For this purpose, the solid PU residue (PU-RS) remaining after acetone separation is reacted with a water-wetted KOH methanol solution (KOH... (MeOH) c = 4 mol / L; water content is approximately 1% by mass; KOH in a 27:1 ratio. (MeOH) The PU-RS mass ratio was reacted at 150°C for 15 hours. The resulting reaction mixture was filtered, and the residue was washed off with MeOH. Filtrate I was neutralized with hydrogen chloride gas or hydrogen chloride methanol solution using phenolphthalein as an indicator, and filtered again. Filtrate II was subjected to a rotary evaporator to remove methanol. The remaining residue was dissolved in CDCl3. Using the resulting CDCl3 phase I, [the reaction proceeds]... 1 H-NMR spectroscopy TDA detection For further investigation, CDCl3 phase I was extracted with hydrochloric acid (c = 1 mol / L) and then separated into an aqueous hydrochloric acid phase containing amines in the form of hydrochloride salts generated by hydrolysis and an organic CDCl3 phase II. The aqueous hydrochloric acid phase obtained after phase separation can also be (after acid neutralization, water evaporation and dissolution in CDCl3) extracted with hydrochloric acid. 1 The study was conducted using H-NMR spectroscopy.

[0078] Chromium acetylacetone (III) was used as a relaxation accelerator. 13The molar ratio of the primary OH end groups in the organic CDCl3 phase II obtained by 13C-NMR spectroscopy was studied as follows: The secondary and primary OH end groups can be clearly distinguished by chemical shift. The carbon atom with a secondary OH group (measured relative to the carbon atoms of the CDCl3 solvent) is 65 ppm to 67 ppm, and the carbon atom with a primary OH group is 60 ppm to 62 ppm. By integrating the areas of the respective signals and forming a ratio, the molar ratio b between the corresponding carbon atoms can be determined, and this ratio corresponds to the molar ratio of the primary OH end groups to the secondary OH end groups: b = n(secondary) / n(primary), where n = molar amount, secondary = secondary OH end group, and primary = primary OH end group.

[0079] Then, the molar proportion x(secondary) of the secondary OH end groups was determined according to the following formula: x(secondary)= n(secondary) / ( n(secondary) + n(primary))= b / (b + 1).

[0080] Multiply by 100 to obtain the corresponding percentage value.

[0081] Preferably, step (A) already includes the preparatory steps for the chemical decomposition in step (B). This is especially the mechanical comminution of the polyurethane foam. Such preparatory steps are known to those skilled in the art; for example, reference can be made to the literature cited in [1]. Depending on the properties of the polyurethane foam, it may be advantageous to "freeze" it before mechanical comminution to facilitate the comminution operation.

[0082] Before, during or after mechanical comminution, the polyurethane foam can be treated with a (water-containing or alcohol-containing) disinfectant. Such disinfectants are preferably hydrogen peroxide, chlorine dioxide, formaldehyde, alkali metal hypochlorites (especially sodium hypochlorite) and / or peracetic acid (water-containing disinfectants), or ethanol, isopropanol and / or 1-propanol (alcohol-containing disinfectants).

[0083] It is also possible to consider carrying out the above preparatory steps at a location spatially separated from the chemical decomposition site. In this case, the prepared foam is transferred to a suitable transport vehicle (such as a silo truck) for further transportation. For further transportation, the prepared foam can also be compressed to obtain a higher mass-volume ratio.

[0084] Chemical decomposition of polyurethane foam Step (B) of the method of the present invention includes the chemical decomposition of the polyurethane foam provided in step (A) by reacting it with an organic chemical decomposition agent and water. This chemical decomposition can be achieved as amino hydrolysis (using a primary or secondary amine or an amino alcohol having a primary or secondary amine as the organic chemical decomposition agent), hydrolysis (using an alcohol as the organic chemical decomposition agent), or a combination of both methods. Hydrolysis is preferred. This is particularly applicable to the chemical decomposition of unfilled polymer polyurethane foam. In each case, a chemical decomposition product is produced, comprising at least one polyether polyol (and optionally other polyols), TDA (and optionally other amines corresponding to isocyanates other than TDI of the isocyanate component), and an organic chemical decomposition agent (which is released again by the hydrolytic cleavage of a urethane and / or urea formed as an intermediate of one or more isocyanates of the isocyanate component and the organic chemical decomposition agent).

[0085] If the chemical decomposition reagent used contains chemically decomposable amines, it is preferably selected from aliphatic primary or secondary organic amines, particularly 1,2-ethylenediamine, 1,4-diaminobutane and / or 1,6-hexanediamine.

[0086] If the chemical decomposition reagent used contains chemically decomposable amino alcohols, it is preferably selected from aliphatic amino alcohols having a primary or secondary amino group, particularly ethanolamine, N-methylethanolamine and / or 3-amino-1-propanol.

[0087] If the chemical decomposition reagent used contains a chemical decomposition alcohol, it is preferably selected from methanol, ethanol, propanol (all isomers, preferably n-propanol), butanol (all isomers, preferably n-butanol), isopropanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl ethylene glycol, triethylene glycol, glycerol and / or 2-methylpropane-1,3-diol.

[0088] Preferably, in step (B), the mass ratio of the organic chemical decomposition reagent and water on one side (1) to the polyurethane foam on the other side (2) (m(1) / m(2); i.e. [m(organic chemical decomposition reagent) + m(water)] / m(polyurethane product); where m represents mass) is set to 0.5 to 2.5, wherein the mass of water is 3.0% to 22% of the mass of the chemical decomposition reagent.

[0089] Step (B) is preferably performed at a temperature of 100°C to 195°C, more preferably 110°C to 190°C, and even more preferably 115°C to 160°C and 900 mbar. (绝对) Up to 2000 millibars (绝对) 950 millibars is preferred (绝对) Up to 1500 millibars (绝对) More preferably 1000 millibars (绝对) Up to 1300 millibars (绝对)It is carried out under pressure, especially at atmospheric pressure, where reflux cooling is used when necessary.

[0090] Regarding the order of adding reactants in step (B), it is preferred to proceed as follows: Adding reactants to polyurethane foam... (II) First add (1) the organic chemical decomposition reagent but before adding water, or (2) add the organic chemical decomposition reagent and the water from the first part, then (II) Add water (1) or water (2) from the second part.

[0091] This facilitates the hydrolytic cracking of the isocyanate of the polyurethane bond or isocyanate component with the carbamate or urea formed as an intermediate by the organic chemical decomposition agent. In this embodiment, it is particularly preferred that water (1) or a second portion of water (2) is added continuously or in batches in step (II) such that the temperature difference between the liquid phase during step (II) and the liquid phase in step (I) is at most 20°C, preferably at most 15°C, more preferably at most 10°C, even more preferably at most 5.0°C, and most preferably at most 1.0°C. In the variant (2) of step (I), preferably, the first portion of water is at most 4.0% of the total mass of water added in step (B) (i.e., together in (I) and (II)), particularly 2.0% to 4.0%.

[0092] Preferably, the chemical decomposition in step (B) is carried out in the presence of a catalyst. Suitable catalysts include, in particular, hydroxides (especially alkali metal or alkaline earth metal hydroxides), carboxylates (especially acetates) (especially alkali metal or alkaline earth metal carboxylates), tin compounds (especially dibutyltin dilaurate or tin(II) octoate [= 2-ethylhexanoate tin(II)]), zinc compounds (especially zinc acetate), carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrophosphophosphates (especially alkali metal or alkaline earth metal monohydrophosphophosphates), metaphosphates (especially alkali metal or alkaline earth metal metaphosphates), or mixtures of two or more of the catalysts described above. The catalyst is preferably selected from carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrophosphophosphates (especially alkali metal or alkaline earth metal monohydrophosphophosphates), or mixtures of two or more of the catalysts described above. The mass ratio of catalyst to polyurethane foam (for all catalysts) is preferably from 0.001 to 0.035.

[0093] Organic chemical decomposition reagents and (optional) distillation of amines In step (C) of the method of the present invention, the organic chemical decomposition reagent is distilled off from the chemical decomposition product, wherein a chemical decomposition product with depleted organic chemical decomposition reagent is obtained. Solid components can be separated before and / or after distillation as described above. Suitable distillation conditions depend on the type of organic chemical decomposition reagent used, which can be readily determined by those skilled in the art. Preferably, the organic chemical decomposition reagent distilled off in step (C) is optionally returned to step (B) after purification (particularly by distillation).

[0094] Similarly, in step (C), toluene diamine (TDA) generated in step (B), along with optional other amines (particularly methylene diphenylene diamine), can be distilled from the chemical decomposition products. Since the boiling points of TDA and optional other amines are generally higher than those of the organic chemical decomposition reagent, it is preferable to first distill off the chemical decomposition reagent, and then distill off TDA or TDA and optional other amines at a higher temperature. Alternatively, and / or in combination with this operation (i.e., when only a portion of the TDA / optionally other amines is distilled off in step (C), TDA and optional other amines generated in step (B) can also be obtained from the acidic aqueous phase obtained from the extraction in step (D) (see step (F) below).

[0095] Whether or not the TDA generated in step (B) and optionally any other amines present are completely or partially distilled from the chemical decomposition products in step (C), the type of evaporator described in step (DI) of WO2023 / 099420 A1 is preferred for distilling off the organic chemical decomposition reagent, namely, a falling film evaporator, a natural circulation evaporator, a tank evaporator, a forced circulation evaporator, or a flash evaporator. If at this point only the chemical decomposition reagent is to be distilled off, without distilling off TDA (and optionally other amines), care should be taken to ensure a sufficient boiling point difference between the chemical decomposition reagent used and the amine with the lowest boiling point (which is usually TDA). If TDA and optionally other amines present are also to be distilled off, this is of course not important, and the chemical decomposition reagent and (one or more) amines can be distilled off together.

[0096] Preferably, a second distillation and / or stripping is performed after a first distillation using one of the aforementioned evaporator types. This second distillation is preferably performed using one of the evaporator types described in step (D.II) of WO 2023 / 099420 A1, namely a thin-film evaporator, a short-path evaporator, or a flash evaporator, with a thin-film evaporator or a short-path evaporator being particularly preferred. The stripping operation is used to remove any residual chemical decomposition reagents that may still be present and have not been separated by the previous distillation steps, as well as (if necessary) TDA (and other amines that may be present), preferably using steam or an inert gas (e.g., nitrogen), especially in a column, preferably a column packed with loose or structured packing.

[0097] Regardless of the source of the recovered TDA / other amines, they are preferably used, optionally after purification (particularly by distillation (which also separates different amines from each other)), for the production of isocyanates (= the corresponding isocyanates) (new production). Methods known per se are suitable for this purpose, particularly those involving the phosgenation of the recovered TDA / other amines. The isocyanates thus prepared can readily react with polyols to produce polyurethanes, particularly polyurethane foams. Suitable polyols may also be at least one polyether polyol obtained in step (E).

[0098] Extraction of polyether polyols Step (D) of the method of the present invention comprises extracting the at least one polyether polyol from the chemical decomposition products of a depleted organic chemical decomposition reagent (and optionally solid components and optionally TDA / other amines). The extraction is carried out using a (water-insoluble) organic solvent. An acid and water are added, particularly an aqueous acid (optionally in combination with more water). Suitable acids are, for example, hydrogen chloride gas, hydrochloric acid, sulfuric acid, phosphoric acid, sulfonic acids (especially p-toluenesulfonic acid and methanesulfonic acid), and carboxylic acids (especially trifluoroacetic acid, oxalic acid, formic acid, and acetic acid, with formic acid and acetic acid being preferred). The order of addition of the organic solvent, acid, and water is variable and not critical for the successful application of the method of the present invention. While the method of the present invention can be carried out in principle with various addition orders, it may be advantageous to add the organic solvent first, followed by the acid / water, for accelerating subsequent phase separation. If an aqueous acid is used, the preferred order of addition is: (1) organic solvent, (2) optionally more water, (3) aqueous acid. If the acid used is non-aqueous, the preferred order of addition is: (1) organic solvent, (2) water, (3) acid.

[0099] After separating the acidic aqueous phase, a polyol phase comprising an organic solvent and at least one polyether polyol is obtained. Preferably, acid and water (especially in the form of an aqueous acid and optionally more water) are added to achieve a pH of 0.0 to 5.0, especially 2.5 to 5.0, preferably 3.0 to 4.5, and more preferably 3.7 to 4.2. The organic solvent is preferably selected from aromatic hydrocarbons, water-insoluble ethers, halogenated (aliphatic or aromatic) hydrocarbons, or mixtures of two or more of the aforementioned solvents. Extraction is preferably carried out at 10°C to 80°C, more preferably at 20°C to 60°C.

[0100] In the extraction of step (D), preferably, the ratio of the mass m(3) of the chemical decomposition product of the depleted organic chemical decomposition reagent (and optionally solid components and optionally amines) to the mass m(4) of the organic fraction of the extractant is... m(3) / m(4) = (where m is the mass) The value is 0.03 to 3.0. Here, "m[organic solvent]" refers to the mass of the organic solvent present in the extractant. Depending on the specific circumstances, different values ​​within this range may be advantageous, for example, values ​​from 0.04 to 2.8 or from 0.10 to 2.0. The most suitable value for a specific situation can be easily determined through simple preliminary testing. The general goal is to keep the amount of organic solvent used as low as possible. The total extractant used comprises 20% to 80% by mass of organic solvent and 20% to 80% by mass of aqueous components, based on its total mass. The term "aqueous components" refers to the sum of all aqueous components, i.e., in the preferred embodiment by adding an acid in the form of an aqueous acid and optionally more water.

[0101] Post-treatment of the polyol phase yields polyether polyols and optional TDA. The polyol phase obtained in step (D) is then post-treated in step (E) to obtain at least the polyether polyol. This post-treatment preferably includes distillation and / or stripping. Regardless of the exact method of post-treatment, it is preferable to react the polyether polyol obtained in step (E) with an isocyanate to produce polyurethane, particularly polyurethane foam.

[0102] If the TDA generated during the chemical decomposition has not yet been distilled off in step (C), it exists in a protonated form in the acidic aqueous phase obtained in step (D). In this case, preferably, the acidic aqueous phase is post-treated in step (F) to obtain TDA. This post-treatment specifically includes neutralization with alkali (optionally "excessive"), followed by phase separation and / or distillation and / or stripping. The recovered TDA is preferably used for the new production of isocyanates, optionally after purification (particularly by distillation). If other amines besides TDA are present in the acidic aqueous phase, they can be separated using separation techniques known per se. For example, methylenediphenylene diamine and polymethylene polyamines (which, unlike TDA, are insoluble in water) can be separated by phase separation after neutralization, optionally aided by the addition of an organic solvent (particularly the same organic solvent used in the extraction in step (D)).

[0103] Example: raw material: In the following experiments, polyurethane foam prepared according to the following formulation served as the starting material for chemical decomposition: serial number reagents Quality 1 Polyether polyol 1 77.5 2 Polyether polyol 2 22.5 3 water 2.5 4 Polyether siloxane 0.88 5 Niax A1 0.1 6 Dabco T-9 0.16 7 Desmodur T 80 33.4 8 index 108

[0104] Remark: 1) Polyether polyols with secondary OH end groups from Covestro Deutschland AG. 2) Polymer-filled (styrene-acrylonitrile) polyether polyols with secondary OH end groups from Covestro Deutschland AG. 3) Deionized water, 4) Polyether siloxane additives from Evonik AG. 5) Amine catalysts from Momentive Performance Materials 6) Tin catalysts from Air Products, 7) Desmodur T80 is a mixture of isomers of 2,4-TDI and 2,6-TDI from Covestro Deutschland AG. 8) The amount of NCO groups used per 100 mol of OH groups.

[0105] analyze: Amine value determination. The amine value represents the number of milligrams of potassium hydroxide required to neutralize the free organic amines present in 1 gram of sample. This includes primary, secondary, and tertiary amines. Amino acids are weak bases. The solvent used is concentrated acetic acid (glacial acetic acid, 99% to 100%). The amine is protonated by the solvent, thus converting it into the corresponding acid, which, along with the deprotonated acid of glacial acetic acid, now exists as an ion pair. Titration is then performed using 0.1 mol perchloric acid as the titrant, in which the perchloric acid displaces the anions of the solvent (glacial acetic acid). The amount of perchloric acid consumed is equal to the amount of potassium hydroxide consumed. The amine value is usually expressed as milligrams of potassium hydroxide per gram of analytical sample, calculated as follows: in • AZ represents the amine value. • V represents the volume of perchloric acid solution consumed. • m represents the mass of the sample being titrated. • M(KOH) represents the molar mass of KOH (56.11 g·mol⁻¹) -1 ), · b i This represents the molar concentration of the perchloric acid solution. • f represents the dimensionless factor (titer) of the perchloric acid solution.

[0106] Degree of protonation. The degree of protonation is a measure of the amount of acid added. If the amount of acid added matches the theoretical amount required to protonate all amine groups, the degree of protonation is 100%.

[0107] pH values ​​were measured using an Accumet AP 110 brand pH meter and glass electrode at their respective stated temperatures.

[0108] NMR spectroscopy: for 1 For H-NMR analysis, the sample is dissolved in a deuterated solvent, such as chloroform, DMSO, or acetone. The choice of deuterated solvent depends on the signal position of the compound under study. Pyrazine is used as the internal standard.

[0109] Implementation Example Overview: Examples 1a and 1b: Hydrolysis or amino hydrolysis of PU foam.

[0110] Examples 2a and 2b: Distillation of organic chemical decomposition reagents and filtration.

[0111] Examples 3a to 3c: Extraction was carried out by pre-distillation and filtration (as described in Examples 2a and 2b) and by adding acid (extraction experiments of the present invention).

[0112] Example 4: Extraction without distillation and acid addition (comparative experiment).

[0113] Example 5: Extraction by pre-distillation and filtration (as described in Example 2b), but without the addition of acid (comparative experiment).

[0114] Example 1a: Hydrolysis of polyurethane foam (steps (A) and (B) of the method of the present invention) In a 1000 mL four-necked flask equipped with a stirrer, thermometer, and cooling device, 300 g of diethylene glycol (DEG) and 5.5 g of sodium carbonate were pre-added and heated to 180 °C under nitrogen protection. 300 g of the polyurethane foam composition was added with stirring and allowed to dissolve. After dissolution, the mixture was stirred at 180 °C for 2 hours, followed by the metered addition of 17 g of water over a 1-hour period to prevent the reaction temperature from dropping below 160 °C. After the water addition was complete, stirring was continued at 160 °C to 180 °C for another 2 hours.

[0115] The reaction mixture 1 In the H-NMR spectrum, TDI-based carbamates were no longer detected; only TDA was detected. Therefore, hydrolysis has been completed.

[0116] Example 1b: Amine hydrolysis of polyurethane foam (steps (A) and (B) of the method of the present invention) In a 1000 mL four-necked flask equipped with a stirrer, thermometer, and cooling device, 300 g of ethanolamine and 3 g of sodium carbonate were pre-added and heated to 150 °C under nitrogen protection. 300 g of the polyurethane foam of the above composition was added with stirring and allowed to dissolve. After dissolution, the mixture was stirred at 150 °C for 2 hours, and then 18 g of water was added over a 30-minute period to prevent the reaction temperature from dropping below 150 °C.

[0117] The reaction mixture 1 In the H-NMR spectrum, TDI-based carbamates were no longer detected; only TDA was detected. Therefore, hydrolysis has been completed.

[0118] Examples 2a and 2b: Distillation (step (C)) and filtration of organic chemical decomposition reagents – general procedures After hydrolysis (Example 1a) or amino hydrolysis (Example 1b), the organic chemical decomposition reagents and excess water used are removed from the respective chemical decomposition products by distillation at a temperature of 150 to 180°C by continuously reducing the pressure to less than 20 mbar, wherein the residual content of the organic chemical decomposition reagents is usually <5%.

[0119] According to 1H-NMR / 2D-NMR spectral analysis using an internal standard, the chemical decomposition products from the depleted organic chemical decomposition reagent obtained in Example 1a typically have the following composition: 3.7% TDA; 6.0% SAN polymer; 88.0% polyether polyol; 2.3% DEG.

[0120] According to 1H-NMR / 2D-NMR spectral analysis using an internal standard, the chemical decomposition products from the depleted organic chemical decomposition reagent obtained in Example 1b typically have the following composition: 4.6% TDA; 5.9% SAN polymer; 74.4% polyether polyol; 4.6% 2-oxazolidinone (byproduct of ethanolamine).

[0121] In both cases, filtration was performed after distillation. A pressure filtration device was used for this purpose, employing a T5500 depth filter from Pall, pre-coated with diatomaceous earth, at an overpressure of 0.5 to 2.5 bar. The pre-coating of the filter was prepared as follows: A 5% diatomaceous earth (“Celite 545”) diethylene glycol suspension was prepared using a Pendraaulik laboratory dissolver Disperlux LR 34 at 1000 rpm, followed by filtration through a T5500 depth filter to a depth of 140 mm. 2 A coating of approximately 25 g Celite 545 is formed on the diameter of the filter.

[0122] According to 1H-NMR / 2D-NMR spectral analysis using an internal standard, the chemical decomposition products of the filtered, depleted organic chemical decomposition reagent from Example 1a typically have the following composition: 3.7% TDA; 0.5% SAN polymer; 95.2% polyether polyol; 0.6% DEG.

[0123] According to 1H-NMR / 2D-NMR spectral analysis using an internal standard, the chemical decomposition products of the filtered, depleted organic chemical decomposition reagent from Example 1b typically have the following composition: 3.8% TDA; 0.2% SAN polymer; 93% polyether polyol; 3.2% 2-oxazolidinone (byproduct of ethanolamine).

[0124] Example 3a: Extraction (Step (D) of the method of the present invention) The chemical decomposition products of the hydrolysis of Example 1a were distilled (according to Example 2a), and the remaining product mixture was mixed with dichloromethane and water in the following mass ratio, wherein the amine value was determined after the addition of dichloromethane: The product mixture: dichloromethane: water = 0.11:1:1. Subsequently, based on the amine value determination results, 100% protonation was established by adding 32% hydrochloric acid.

[0125] The resulting mixture was shaken at 50°C, followed by phase separation to form an acidic aqueous phase and an organic polyol phase. Both phases were then concentrated separately on a rotary evaporator at approximately 20 mbar and 120°C until no further evaporation of volatile components was observed. 1 H-NMR spectroscopy analysis was performed. The following composition was determined: • Concentrated acidic aqueous phase: 96.4% TDA hydrochloride; 0.1% polyether polyol; 3.5% diethylene glycol. • Concentrated polyol phase: 92.0% polyether polyol; 8.0% diethylene glycol.

[0126] Example 3b: Extraction (Step (D) of the method of the present invention) A portion of the product mixture remaining after distillation and filtration (according to Example 2a) of the chemical decomposition products of hydrolysis in Example 1a was mixed with dichloromethane and water in the following mass ratio: The product mixture: dichloromethane: water = 0.11:1:1. A pH of 4.0 was then established by adding 32% hydrochloric acid.

[0127] The resulting mixture was shaken at 50°C, followed by phase separation to form an acidic aqueous phase and an organic polyol phase. Both phases were then concentrated separately on a rotary evaporator at approximately 20 mbar and 120°C until no further evaporation of volatile components was observed. 1 H-NMR spectroscopy analysis was performed. The following composition was determined: • Concentrated acidic aqueous phase: 51.3% TDA hydrochloride; 48.0% TDA; 0.7% polyether polyol. • Concentrated polyol phase: 97.0% polyether polyol; 0.8% TDA; 2.2% diethylene glycol.

[0128] Example 3c: Extraction (Step (D) of the method of the present invention) A portion of the product mixture remaining after distillation and filtration (according to Example 2b) of the chemical decomposition products of hydrolysis in Example 1b was mixed with dichloromethane and water in the following mass ratio: The product mixture: dichloromethane: water = 0.11:1:1. A pH of 4.0 was then established by adding 32% hydrochloric acid.

[0129] The resulting mixture was shaken at 50°C, followed by phase separation to form an acidic aqueous phase and an organic polyol phase. Both phases were then concentrated separately on a rotary evaporator at approximately 20 mbar and 120°C until no further evaporation of volatile components was observed. 1 H-NMR spectroscopy analysis was performed. The following composition was determined: • Concentrated acidic aqueous phase: 96% TDA hydrochloride; 0.2% polyether polyol; 3.8% 2-oxazolidinone (a byproduct of ethanolamine). • Concentrated polyol phase: 99.0% polyether polyol; 1.0% TDA.

[0130] Example 4: Extraction without pre-distillation of organic chemical decomposition reagents or addition of acid (comparative) A portion of the chemical decomposition product from the hydrolysis of Example 1a was mixed with cyclohexane in the following mass ratio: Product mixture:cyclohexane = 1:3.

[0131] The resulting mixture was shaken at 25°C, followed by phase separation to form the DEG and cyclohexane phases. Both phases were then concentrated separately on a rotary evaporator at approximately 20 mbar and 120°C until no further evaporation of volatile components was observed. 1 H-NMR spectroscopy analysis was performed. The following composition was determined: • Concentrated DEG phase: 11.8% TDA; 79.7% diethylene glycol; 5.3% polyether polyol; 3.2% SAN polymer. • Concentrated cyclohexane phase: 95.6% polyether polyol; 1.1% TDA; 3.3% diethylene glycol.

[0132] If the diethylene glycol and SAN polymer portions are subtracted from the aqueous phase, 69.0% TDA and 31.0% polyether polyol are obtained. Therefore, the separation of TDA and polyether polyol is far less efficient than in the embodiments of the present invention.

[0133] Example 5: Extraction by pre-distillation and filtration (as described in Example 2b), but without the addition of acid (comparative experiment). A portion of the product mixture remaining after distillation and filtration (according to Example 2b) of the chemical decomposition product of amino hydrolysis in Example 1b was mixed with chloroform and water in the following mass ratio: Product mixture: chloroform: water = 0.11:1:1.

[0134] The resulting mixture was shaken at 50°C. An emulsion was formed, and after a standing time of approximately 1.5 hours, it separated into two phases. Each phase was then concentrated separately on a rotary evaporator at approximately 20 mbar and 120°C until no further evaporation of volatile components was observed. 1 H-NMR spectroscopy analysis was performed. The following composition was determined: • Concentrated aqueous phase: 40% TDA; 0.4% polyether polyol; 59.6% byproducts from ethanolamine and TDA (e.g., 2-oxazolidinone, N,N'-bis(2-hydroxyethyl)urea, other byproducts). • Concentrated polyol phase: 90.0% polyether polyol; 7.0% TDA; 3.0% byproducts from TDA and ethanolamine.

[0135] Compared with Example 3c, it was found that the separation of TDA and polyol was significantly worse, and the proportion of by-products was also greatly increased.

Claims

1. A method for recovering valuable substances from polyurethane foam, comprising the following steps: (A) Provides a polyurethane foam based on an isocyanate component and a polyol component, wherein the isocyanate component comprises toluene diisocyanate, and wherein the polyol component comprises a polyether polyol; (B) Polyurethane foam undergoes chemical decomposition through reaction with organic chemical decomposition agents and water. The organic chemical decomposition reagents mentioned therein are selected from: (i) primary or secondary chemical decomposition amines, (ii) chemical decomposition amino alcohols having primary or secondary amino groups, (iii) chemical decomposition alcohols, or (iv) mixtures of two or more of the organic chemical decomposition reagents. To obtain chemical decomposition products containing polyether polyol, toluene diamine, and organic chemical decomposition reagents; (C) Distilling the organic chemical decomposition reagent from the chemical decomposition product to obtain a chemical decomposition product with depleted organic chemical decomposition reagent, wherein solid components can be separated before and / or after distillation; (D) Extract polyether polyols from the chemical decomposition products of depleted organic chemical decomposition reagents using an organic solvent, wherein acid and water are added, and after separating the acidic aqueous phase, a polyol phase containing organic solvent and polyether polyol is obtained. and (E) Post-treatment of the polyol phase to obtain polyether polyol.

2. The method of claim 1, wherein the polyether polyol comprises a polyether polyol filled with a polymer, wherein the polymer comprises a polymer containing a vinyl monomer, a polyurea, and / or a polyurethane.

3. The method as described in any of the preceding claims, wherein the polyol component contains no other polyols besides polyether polyols.

4. The method as described in any of the preceding claims, In addition to toluene diisocyanate, the isocyanate component also includes methylene diphenyl diisocyanate or a mixture of methylene diphenyl diisocyanate and polymethylene polyphenyl polyisocyanate, or The isocyanate component contains no other isocyanates except for toluene diisocyanate.

5. The method as described in any of the preceding claims, wherein (i) The primary or secondary chemically decomposed amines include aliphatic primary or secondary organic amines; (ii) Chemically decomposed amino alcohols include aliphatic amino alcohols having primary or secondary amino groups; and / or (iii) Chemically decomposed alcohols include methanol, ethanol, propanol, butanol, isopropanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl ethylene glycol, triethylene glycol, glycerol, 2-methylpropane-1,3-diol, or mixtures of two or more of the alcohols mentioned above.

6. The method as claimed in any of the preceding claims, wherein the mass ratio of the organic chemical decomposition reagent and water to the polyurethane foam of the other side (2) is 0.5 to 2.5, and wherein the mass of water is 3.0% to 22% of the mass of the chemical decomposition reagent.

7. The method as described in any of the preceding claims, wherein step (B) is performed at a temperature of 100°C to 195°C and 900 mbar. (绝对) Up to 2000 millibars (绝对) It was carried out under pressure.

8. The method as described in any of the preceding claims, wherein the extraction in step (D) is carried out at a temperature of 10°C to 80°C.

9. The method as claimed in any of the preceding claims, wherein in step (D), the mass ratio of the chemical decomposition product of the depleted organic chemical decomposition reagent to the mass of the organic solvent present in the extractant is... The value is 0.03 to 3.0, where m = mass, and the extractant contains 20% to 80% by mass of organic solvent and 20% to 80% by mass of aqueous components, based on their total mass.

10. The method of any of the preceding claims, wherein the polyether polyol obtained in step (E) reacts with isocyanate to generate polyurethane.

11. The method as described in any of the preceding claims, comprising: (F) Post-treatment of the acidic aqueous phase to obtain toluene diamine.

12. The method as claimed in any of the preceding claims, wherein in step (C) toluene diamine is also partially or wholly distilled from the chemical decomposition products.

13. The method of any one of claims 11 to 12, wherein the toluene diamine obtained in step (F) and / or the toluene diamine distilled in step (C) is optionally used, after purification, to prepare toluene diisocyanate.

14. The method of claim 13, wherein toluene diisocyanate reacts with a polyol to generate polyurethane.

15. The method of any of the preceding claims, wherein the polyether polyol contains >45% secondary OH end groups in molar proportion.

16. The method of any of the preceding claims, wherein the acid is selected from hydrogen chloride gas, hydrochloric acid, sulfuric acid, phosphoric acid, sulfonic acid, carboxylic acid, or a mixture of two or more of the aforementioned acids.

17. The method as claimed in any of the preceding claims, wherein the acid and water are added in the form of an aqueous acid in step (D).

18. The method of claim 17, wherein more water is added in addition to the aqueous acid.

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