Method for recovering raw materials from polyurethane products

Abstract

The present invention relates to a method for recovering raw materials from a polyurethane product, the method comprising a chemical decomposition process, characterized in that the polyurethane product is reacted with (i) an amine chemical decomposition reagent selected from (a) a primary organic amine or a secondary organic amine, (b) an amino alcohol having a primary amino group or a secondary amino group, or (c) a mixture of (a) and (b), and (ii) water in the presence of (iii) a catalyst at a temperature ranging from 100°C to 195°C and a pressure ranging from 900mbar (abs) to 2000mbar (abs), where the mass ratio of the amine chemical decomposition reagent and water to the polyurethane product is in the range of 0.5 to 2.5, and the mass of the water is in the range of 3.0% to 22% of the mass of the amine chemical decomposition reagent.

Description

[Technical field]

[0001] The present invention relates to a method for recovering raw materials from polyurethane products, particularly polyurethane foams, comprising chemical decomposition, characterized in that the polyurethane product is treated with an amine chemical decomposition agent selected from (a) a primary organic amine or a secondary organic amine, (b) an amino alcohol having a primary amino group or a secondary amino group, or (c) a mixture of (a) and (b), and (ii) water, in the presence of (iii) a catalyst, at a temperature of 100° C. to 195° C. and 900 mbar. (abs.) ~2000mbar (abs.) wherein the mass ratio of the amine chemical decomposition reagent and water on the one hand to the polyurethane product on the other hand is in the range of 0.5-2.5, and the mass of the water is 3.0%-22% of the mass of the amine chemical decomposition reagent. [Background technology]

[0002] Polyurethane foams have a variety of applications in industry and in everyday life. They are usually divided into rigid and flexible foams. Despite their heterogeneity, the basic polyurethane structure is common to all these products, which is formed by the polyaddition reaction of multifunctional isocyanates with polyols, for example in the case of polyurethanes based on diisocyanates O=C=NRN=C=O and diols HO-R'-OH, where R and R' represent organic radicals: ~~~[O-R'-O-(O=C)-HN-R-NH-(C=O)]~~~ It can be expressed as:

[0003] The great economic success of polyurethane products is the reason for the generation of large amounts of polyurethane waste (e.g. from old mattresses or seating furniture), which must be used rationally. The technically easiest recycling method to implement is incineration, where the heat of combustion released is used in other processes, for example industrial processes. However, this does not allow the raw material cycle to be completed. Another recycling method is called "physical recycling", where polyurethane waste is mechanically comminuted and used to manufacture new products. This type of recycling, of course, has limitations, so attempts to recover the basic raw materials for polyurethane production by retrocleavage of polyurethane bonds (called "chemical recycling") are not eliminated. These raw materials to be recovered mainly include polyols (i.e., in the above example, HO-R'-OH). In addition, it is also possible to recover amines by hydrolytic cleavage of urethane bonds (i.e., in the above example, H2N-R-NH2), which can be phosgenated after workup to obtain isocyanates (in the above example, O=C=NRN=C=O). An overview of known polyurethane recycling methods is given in a review by Friedrich Schneider, eds., 2003, 144:1311-1322, which highlights glycolysis (number 2. below) as being of particular importance.

[0004] A variety of chemical recycling approaches have been developed so far. Four of these can be briefly summarized as follows: 1. Hydrolysis of urethanes by reaction with water to recover amines and polyols and form carbon dioxide. 2. Glycolysis of urethanes by reaction with alcohol, where the polyol incorporated in the urethane group is replaced by the alcohol used, releasing the polyol. This process is commonly referred to in the literature as transesterification (more correctly, transurethanization). Regardless of the exact nature of the alcohol used, this method of chemical recycling is usually referred to in the literature as glycolysis. It is more correct to refer to it more generally as alcoholysis, since this is a term that actually applies only to glycols. Glycolysis may be followed by hydrolysis. If the hydrolysis is carried out in the presence of the still unchanged glycolysis mixture, it is referred to as hydroglycolysis. 3. Hydroglycolysis of urethane bonds. Of course, it is also possible to add alcohol and water from the beginning, in which case the above hydrolysis and glycolysis processes proceed in parallel. 4. Aminolysis of the urethane bond by reaction with primary and secondary amines, in which the polyol incorporated in the urethane group is replaced by the amine used, releasing the polyol. In this case, the urethane group is converted into a urea group. It is also possible to cleave the R-NH-(C=O)- bond in the urethane and replace the R-NH- group with the amine used for aminolysis, releasing the amine R-NH2 corresponding to the isocyanate initially used. When using amino alcohols with primary or secondary amino groups, it is of course also possible for the alcohol group of the amino alcohol used to react with the urethane bond, so that carbamates can be formed. According to the prior art cited below, aminolysis is followed in a separate step by hydrolysis.

[0005] Patent document 1 describes a method for the chemical degradation of polyurethanes, in which the chemical degradation is preceded by mechanical comminution (wet grinding) of the polyurethane starting material, which is recycled in a wet state. For this purpose, the polyurethane starting material is mixed with a portion of the polyol obtained by chemical degradation. The process is started with the polyol from a previous chemical degradation process. The chemical degradation can be carried out as glycolysis, hydrolysis, methanolysis or aminolysis, preferably glycolysis. There is no mention of a combination of aminolysis and hydrolysis. Suitable catalysts are standard catalysts such as sodium hydroxide, potassium hydroxide, sodium alkoxides, potassium alkoxides or mixtures thereof. The highlighted advantage of using polyol obtained by chemical degradation to wet the polyurethane starting material is that it does not react with the chemical degradation chemicals and therefore does not destroy the target formulation for the chemical degradation (see especially paragraphs

[0021] ,

[0073] ,

[0074] and

[0078] ).

[0006] Patent Document 2 describes a method for decomposing a polyether polyol-based polyurethane with an amine in the presence of a basic catalyst such as an oxide or hydroxide of an alkali metal or alkaline earth metal. This converts the urethane and urea bonds in the polyurethane, releasing the polyether polyol and obtaining the urea of ​​the amine used in the chemical decomposition. These ureas are cleaved under the influence of a basic catalyst to give amines (i.e., the amines corresponding to the isocyanates used in the synthesis of the polyurethane and the amines used in the chemical decomposition) and carbonates (e.g., sodium carbonate). When ethanolamine (also called 2-aminoethanol, monoethanolamine) is used, 2-oxazolidinone is formed as an intermediate. This is cleaved under the influence of a basic catalyst to give ethanolamine and carbonates.

[0007] In Patent Document 3, in a first step, a polyurethane starting material, in particular a foam (flexible or rigid foam, preferably flexible foam), is dissolved at 120°C to 250°C by adding glycol, polyamine or amino alcohol, followed by optional filtration to remove solids, followed by heating in an autoclave at 200°C to 320°C and 49 bar with water in a second step. (G) ~76bar (G) (50kg / cm 2 G~78kg / cm 2 A two-stage chemical decomposition process is described in which the hydrolysis is carried out in an autoclave at a pressure of 10 ...

[0008] Patent document 4 describes a method in which polyurethane starting material, in particular polyurethane foam (flexible or rigid foam, preferably flexible foam), is first mixed with a polyamine and heated to 120°C to 250°C. This results in the formation of a liquid phase containing a dissolved fraction of polyol and polyurea and a solid phase containing an undissolved fraction of polyurea. The liquid phase is then hydrolyzed in an autoclave at a temperature of 200°C to 320°C and at high pressure (in the examples at least 4.7 MPa = 47 bar). The solid phase can be dissolved in further polyamine and then hydrolyzed in the same way, optionally after removal of the insoluble fraction. For the workup, water is drawn off in gaseous form, distilled off or driven off with an inert gas. The solvent is removed by distillation. The polyol and polyamine formed are separated by distillation, centrifugation or solvent extraction. The amine-containing hydrolyzate can also be reacted with alkylene oxide to obtain a polyol. Patent document 4 mentions that the method is also applicable to rigid foams. However, they often contain polyisocyanates of the diphenylmethane series (pMDI) whose corresponding amines formed by chemical decomposition (polyamines of the diphenylmethane series, pMDA) cannot be distilled without decomposition, and no viable method for recovering such amines has been disclosed.

[0009] In US Pat. No. 5,539,563, an attempt is made to solve the problem of the lack of distillability of pMDA by reacting the chemical decomposition products with alkylene oxides to obtain polyols. However, this procedure does not allow the raw material cycle to be completed. The chemical decomposition method described involves a step of hydrolysis with water under high pressure.

[0010] Patent document 6 describes a process in which rigid foams are dissolved in amines or glycols at 100° C.-250° C. and ambient pressure, followed by hydrolysis. Suitable polyurethane foams disclosed are based on tolylene diisocyanate (TDI) and / or diphenylmethane series diisocyanates (mMDI). Hydrolysis is carried out with supercritical or subcritical water. The pressure range disclosed for hydrolysis is 100 bar-250 bar. Work-up is carried out by fractionation. The recovered amines can be used for the new production of isocyanates or as starters for polyol synthesis.

[0011] The aminolysis method described has the disadvantage that during the reaction of polyurethane with amines or aminoalcohols, urea products and other amine-containing co-products are formed. These amine-containing co-products make it difficult to recover the amines corresponding to the isocyanates originally used in the preparation of the polyurethane and the polyols used in the preparation of the polyurethane. As a result, in a second step, these amine-containing co-products must be subjected to a complex hydrolysis under high pressure.

[0012] Patent document 7 describes a process for separating the chemical decomposition products obtained by hydrolysis of polyurethanes (according to the teaching of patent document 8, i.e. at 100° C. to 300° C. and 5 bar to 100 bar) into polyols or polyamines which can be reused for the production of polyurethane plastics, by introducing hydrogen chloride gas into the hydrolysate mixture, preferably diluted with an inert solvent, in particular toluene, and filtering off the amine salts formed, the precipitation with hydrogen chloride being carried out in fractions (in several partial steps).

[0013] In Patent Document 9, crushed plastic is directly heated in an autoclave under steam pressure of about 20 atm (19.6 bar). (G)A process for recovering polyether polyols from polyurethane plastics is disclosed, in which the reaction product is heated at 150°C to 220°C for at least 1 hour in a vacuum oven. For work-up, the reaction product thus treated can be dissolved in an organic solvent, in particular toluene, mixed with dilute hydrochloric acid and filtered. The remaining organic solution is concentrated by evaporation and filtered, yielding the polyether polyol as a residue.

[0014] According to the prior art, even pure hydrolysis processes require high pressures, which is of course a disadvantage.

[0015] Of the chemical recycling processes known from the literature, only a few are operating sustainably on an industrial scale, and many have not even reached pilot scale (Non-Patent Document 1). Given the general increase in environmental awareness and the growing efforts to make industrial processes as sustainable as possible, both of which fundamentally support chemical recycling, it is clearly shown that chemical recycling of polyurethane products is still far from mature from a technical and economic point of view. There are challenges, especially with regard to the purity of the recovered products. Furthermore, an economical recycling method must ensure that the reagents used (e.g. the alcohols, amino alcohols or amines used) are recovered as completely as possible and can be reused (i.e. following a closed loop). Due to the large amount of polyurethane waste that arises from used polyurethane foams (e.g. refrigerators, hot water tanks, mattresses, chairs, car seats, etc.), the recycling of polyurethane foams is particularly important. In addition, the polyurethane products to be reused usually still contain various auxiliaries and additives (stabilizers, catalysts, etc.), which must be separated and disposed of in an economically viable and environmentally friendly way from the actual product to be recycled. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] US Patent Application Publication No. 2016 / 0347927 [Patent Document 2] U.S. Patent No. 3,404,103 [Patent Document 3] European Patent No. 0990674 [Patent Document 4] European Patent Application Publication No. 1142945 [Patent Document 5] JP 2001-261584 A [Patent Document 6] European Patent Application Publication No. 1149862 [Patent Document 7] European Patent Application Publication No. 0013350 [Patent Document 8] German patent no. 2442387 [Patent Document 9] German patent no. 2207379 [Non-patent literature]

[0017] [Non-Patent Document 1] Simon, Borreguero, Lucas and Rodriguez in Waste Management 2018, 76, 147 - 171 Summary of the Invention [Problem to be solved by the invention]

[0018] Therefore, further improvements are needed in the field of chemical recycling of polyurethane foams. In particular, it is desirable to overcome or at least mitigate the disadvantages outlined above further in relation to aminolysis from the prior art (an essential two-step process regime with a second step under high pressure). This is because aminolysis is an attractive chemical decomposition method in itself, since it allows the direct release of amines corresponding to the isocyanates of the polyurethane product, which are then replaced by more strongly Lewis-basic amine chemical decomposition agents. [Means for solving the problem]

[0019] Considering the above requirements, the present invention provides a method for recovering raw materials from a polyurethane product, comprising the steps of: (A) providing a polyurethane product based on an isocyanate component and a polyol component; (B) (i) an amine chemical decomposition reagent selected from (a) a primary organic amine or a secondary organic amine, (b) an aminoalcohol having a primary amino group or a secondary amino group, or (c) a mixture of a primary organic amine or a secondary organic amine (=a) and an aminoalcohol having a primary amino group or a secondary amino group (=b), and (ii) water, in the presence of (iii) a catalyst, at a temperature of 100°C to 195°C, preferably 110°C to 190°C, more preferably 115°C to 160°C, and at 900 mbar (abs.) ~2000mbar (abs.) , preferably 950 mbar (abs.) ~1500mbar (abs.) , more preferably 1000 mbar (abs.) ~1300mbar (abs.) chemically decomposing the polyurethane product in liquid phase at a pressure of, in particular, ambient pressure, and optionally under reflux cooling, to obtain chemical decomposition products; The mass ratio of (1) the amine chemical decomposition reagent (used as a whole) and water (used as a whole) on the one hand to (2) the polyurethane product on the other hand (m(1) / m(2); i.e., [m(amine chemical decomposition reagent)+m(water)] / m(polyurethane product); here, m represents mass) is in the range of 0.5 to 2.5, and the mass of the water is 3.0% to 22%, particularly 4.0% to 15%, of the mass of the amine chemical decomposition reagent; (C) post-processing the chemical decomposition products to obtain (at least) amines (corresponding to the isocyanates of the isocyanate component) and / or (at least) polyols (corresponding to the polyols of the polyol component or formed from such polyols during chemical decomposition); The present invention provides a method comprising:

[0020] Quite surprisingly, it has been found that the aminolysis of polyurethanes with amines or aminoalcohols, combined with in situ hydrolysis with excess water (i.e. aminohydrolysis), greatly simplifies the recovery of amines and polyols by standard purification methods. The advantage of this combination of aminolysis and in situ hydrolysis compared to the prior art is that the possible co-products that may be formed during the chemical decomposition (particularly urea) are hydrolyzed in situ without significant complexity, in particular without the need to use additional pressure-resistant equipment. The method of the invention makes it possible to carry out the chemical decomposition in a quasi-one-stage manner in a single reactor (but is not limited to the use of a single reactor). The product mixture present after aminohydrolysis contains the amines corresponding to the isocyanates initially used and the polyols of the polyol component (or their low molecular weight (monomeric or oligomeric) decomposition products, depending on the type of polyol component).

[0021] A polyurethane product in the context of the present invention is a polyaddition product (sometimes also called, not entirely correctly, a polycondensation product) of the reaction of a polyfunctional isocyanate (=isocyanate component in the polyurethane preparation) with a polyol (=polyol component in the polyurethane preparation). A polyurethane product generally contains not only the polyurethane basic structure outlined above, but also other structures, for example structures with urea bonds. The presence of such structures, in addition to the polyurethane structure, which deviate from the pure polyurethane basic structure, does not depart from the scope of the present invention. A polyurethane product in the context of the present invention is in particular a polyurethane foam obtained by the reaction of a polyfunctional isocyanate with a polyol in the presence of a blowing agent.

[0022] In the terminology of the present invention, the term isocyanate refers to all isocyanates known to the person skilled in the art in connection with polyurethane chemistry, such as in particular (i) tolylene diisocyanate (TDI; prepared from tolylene diamine, TDA), (ii) methylene diphenylene diisocyanate (= "diisocyanate of the diphenylmethane series", mMDI; prepared from methylene diphenylene diamine, mMDA), (iii) methylene diphenylene diisocyanate (mMDI) and polymethylene polyphenylene polyisocyanate (= "polyisocyanate of the diphenylmethane series"). The term "isocyanate" encompasses mixtures of isocyanates such as (i) pentane 1,5-diisocyanate (PDI; prepared from pentane-1,5-diamine, PDA), (ii) hexamethylene 1,6-diisocyanate (HDI; prepared from hexamethylene-1,6-diamine, HDA), (iii) isophorone diisocyanate (IPDI; prepared from isophorone diamine, IPDA), and (iv) xylylene diisocyanate (XDI; prepared from xylylene diamine, XDA). The term "isocyanate" encompasses embodiments in which two or more different isocyanates (e.g., mixtures of MDI and TDI) are used in the manufacture of the polyurethane product, unless expressly indicated otherwise, for example by the term "exactly one isocyanate". Collectively, all isocyanates used in the preparation of a polyurethane product are referred to as the isocyanate component (of the polyurethane product). The isocyanate component includes at least one isocyanate. Similarly, all polyols used in the preparation of a polyurethane product are referred to as the polyol component (of the polyurethane product). The polyol component includes at least one polyol.

[0023] In the terminology of the present invention, the term polyol includes all polyols known to the skilled person in the art in relation to polyurethane chemistry, such as, in particular, polyether polyols, polyester polyols, polyether ester polyols and polyether carbonate polyols. The expression "polyol" naturally also includes embodiments in which two or more different polyols are used in the manufacture of the polyurethane product. Thus, for example, when referring hereinafter to "polyether polyol" (or "polyester polyol", etc.), this terminology naturally also includes embodiments in which two or more different polyether polyols (or two or more different polyester polyols, etc.) are used in the manufacture of the polyurethane product.

[0024] In the context of step (C), the term polyol may also refer to a polyol formed during chemical decomposition from the polyol originally used in the production of the polyurethane product, however, as explained in more detail further below, the polyol of the polyol component is preferably a polyether polyol that can be so recovered during chemical decomposition.

[0025] A carbamate in the terminology of this invention is any urethane formed by reaction with an amino alcohol in step (B).

[0026] The amine corresponding to the isocyanate is an amine which can be phosgenated to obtain an isocyanate according to the formula R-NH2+COCl2→RN=C=O+2HCl.

[0027] In the context of the method of the present invention, water and amine chemical decomposition reagent are used in superstoichiometric amounts. This means that the amount of water used is theoretically sufficient to hydrolyze all polyurethane bonds to obtain amines and polyols with the release of carbon dioxide. Similarly, the superstoichiometric use of amine chemical decomposition reagent means that the amount used is theoretically sufficient to convert all polyurethane bonds to form ureas or carbamates and polyols. This is usually the case when the following preferred relationship is observed between the mass ratio [m(amine chemical decomposition reagent)+m(water)] / m(polyurethane product) (a) and the mass ratio of water based on the mass of amine chemical decomposition reagent (b).

[0028] TIFF2024544908000001.tif31170

[0029] For example, when a is in the range of 0.5 to 1.0, the value of b should be selected in the range of 10% to 22%, and when a is in the range of more than 1.0 to 1.5, the value of b should be selected in the range of 7.0% to less than 10%.

[0030] The expression "(i) using an amine chemical decomposition reagent selected from (a) a primary organic amine or a secondary organic amine, (b) an amino alcohol having a primary amino group or a secondary amino group, or (c) a mixture of (a) and (b), and (ii) water, and (iii) chemically decomposing the polyurethane product in the liquid phase in the presence of a catalyst" does not necessarily mean that all the water used in step (B) must be added at the very beginning of step (B). Instead, the present invention encompasses embodiments in which no water is added initially at the beginning of step (B), or only a portion of the water is added, and then water or the remainder of the water is added (all at once or, preferably, gradually during the reaction time). In this case, the specification of the content of 3.0% to 22% by mass of the amine chemical decomposition reagent (and, of course, the preferred relationship between a and b specified above) relates to the amount of water added in total in step (B) by the end of the reaction time. In principle, it is also conceivable to gradually add the amine chemical decomposition reagent or a mixture of water and the amine chemical decomposition reagent. In each case, the amounts specified in relation to step (B) relate to the total amount added in each case until the end of the reaction time of that step. The present invention also encompasses an embodiment in which no catalyst is present at the beginning of step (B). For example, it is possible to first add only the amine chemical decomposition agent (without water and without catalyst) to the polyurethane product, and then add water and catalyst, in particular as an aqueous solution of the catalyst. Of course, in this variant, it is also possible to add further water (all at once or gradually during the reaction time).

[0031] The quantitative values ​​for water in step (B) relate to the water added as a reagent for hydrolytic carbamate cleavage. In comparison, the amount of water is small in both cases, especially due to the moisture present in the amine chemical decomposition reagent used. By moisture in the amine chemical decomposition reagent used, we mean the trace amounts of moisture that may occur on an industrial scale even with proper handling and storage. Of course, it is possible to premix the amine chemical decomposition reagent with the water used for hydrolytic cleavage or to wet the polyurethane product with the water used for hydrolytic cleavage. Such an embodiment does not depart from the scope of the present invention, and the water added in this way should of course be taken into account in the quantitative values ​​for step (B), i.e. the amount of water added additionally if necessary should be reduced accordingly. If the catalyst is used in the form of an aqueous solution, the water used as a solvent should likewise be taken into account in the quantitative values ​​for step (B), i.e. the amount of water added additionally if necessary should be reduced accordingly.

[0032] Pressure figures in the context of the present invention are always expressed as absolute pressures, identified by the subscript "abs." following the unit of pressure (e.g., an absolute pressure of 900 mbar is expressed as "900 mbar (abs.) "). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] First, a summary of various possible embodiments of the present invention follows.

[0034] In a first embodiment of the present invention, which can be combined with all other embodiments, the polyurethane product in step (B) is (I) first (1) mixed with an amine chemical decomposition reagent but not yet mixed with water, or (2) mixed with a first portion of an amine chemical decomposition reagent and water, and then (II) Water (1) or a second portion of water (2) is added, especially after the polyurethane product has gone into solution.

[0035] Here, it is possible, and this is preferred, to add the catalyst already in step (I), or alternatively, it is possible to add the catalyst only in step (II), in particular as an aqueous catalyst solution, to the polyurethane product, in particular after the polyurethane product has gone into solution.

[0036] In a second embodiment of the invention, which is a particular configuration of the first embodiment, in step (II), water (1) or the second portion of water (2) is added continuously or in portions such that the temperature of the liquid phase in step (II) differs from the temperature of the liquid phase in step (I) by at most 20°C, preferably at most 15°C, more preferably at most 10°C, even more preferably at most 5.0°C, very exceptionally preferably at most 1.0°C.

[0037] In a third embodiment of the present invention, which is a specific configuration of the first and second embodiments, in (I)(2), the first portion of water is up to 4.0%, in particular 2.0% to 4.0%, of the mass of water added in step (B) as a whole (i.e. (I) and (II) combined).

[0038] In a fourth embodiment of the invention, which can be combined with all other embodiments, the amine chemical decomposition reagent (a) is an aliphatic primary or secondary organic amine, (b) an aliphatic amino alcohol having a primary or secondary amino group, or (c) a mixture of the two.

[0039] In a fifth embodiment of the invention, which can be combined with all other embodiments, especially the fourth embodiment, the primary or secondary organic amine (a) is a monoamine, a diamine, or a mixture of monoamines and diamines.

[0040] In a sixth embodiment of the present invention, which can be combined with all other embodiments, the amine chemical decomposition reagent is selected from ethanolamine, N-methylethanolamine, 3-amino-1-propanol, ethylene-1,2-diamine, 1,4-diaminobutane, hexamethylene-1,6-diamine or a mixture of two or more of the abovementioned amine chemical decomposition reagents.

[0041] In a seventh embodiment of the invention, which can be combined with all other embodiments, 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 (=tin(II) 2-ethylhexanoate)), zinc compounds (especially zinc acetate), carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrogen orthophosphates (especially alkali metal or alkaline earth metal monohydrogen orthophosphates), metaphosphates (especially alkali metal or alkaline earth metal metaphosphates) or a mixture of two or more of the abovementioned catalysts.

[0042] In an eighth embodiment of the invention, which is a particular configuration of the seventh embodiment, the catalyst is selected from a carbonate (especially an alkali metal or alkaline earth metal carbonate), an orthophosphate (especially an alkali metal or alkaline earth metal orthophosphate), a monohydrogen orthophosphate (especially an alkali metal or alkaline earth metal monohydrogen orthophosphate), or a mixture of two or more of the abovementioned catalysts.

[0043] In the ninth embodiment of the present invention, which can be combined with all other embodiments, especially the seventh and eighth embodiments, the mass ratio of catalyst to polyurethane product is in the range of 0.001 to 0.035.

[0044] In a tenth embodiment of the present invention, which can be combined with all other embodiments, step (II) is carried out in a chemical decomposition reactor selected from a stirred tank (in particular a jacketed stirred tank), a tubular reactor or a combination of the two.

[0045] In an eleventh embodiment of the invention, which can be combined with all other embodiments, step (C) comprises liquid-liquid extraction with an extractant and phase separation into a first product phase comprising the amine or a salt of the amine and a second product phase comprising the polyol.

[0046] In a twelfth embodiment of the present invention, which is a specific configuration of the eleventh embodiment, the liquid-liquid extraction is preceded by a distillative separation of the amine chemical decomposition reagent from the chemical decomposition products.

[0047] In a thirteenth embodiment of the present invention, which is a specific configuration of the eleventh and twelfth embodiments, the mass ratio of the mixture to be extracted (= chemical decomposition product or product mixture) to the extractant in liquid-liquid extraction is 0.5 to 1.5, preferably 0.7 to 1.3, more preferably 0.9 to 1.1, and particularly 1.0.

[0048] In a fourteenth embodiment of the present invention, which is a specific configuration of the eleventh to thirteenth embodiments, the isocyanate component comprises tolylene diisocyanate (TDI), and the extractant comprises (i) an organic solvent selected from an (aliphatic or aromatic) hydrocarbon or a halogen-substituted, particularly a chlorinated, (aliphatic or aromatic) hydrocarbon, and (ii) water.

[0049] In a fifteenth embodiment of the invention, which is a specific configuration of the fourteenth embodiment, an amine, in this embodiment tolylenediamine (TDA), is distilled from the first product phase.

[0050] In a sixteenth embodiment of the present invention, which is a specific configuration of the fourteenth and fifteenth embodiments, the second product phase is purified by distillation and / or stripping to obtain a polyol.

[0051] In a seventeenth embodiment of the present invention, which is a specific configuration of the fourteenth to sixteenth embodiments, the organic solvent is selected from cyclohexane, toluene, methylene chloride, chloroform, chlorinated aromatic hydrocarbons (especially chlorobenzene or ortho-dichlorobenzene, etc.) or a mixture of two or more of the aforementioned organic solvents.

[0052] In the 18th embodiment of the present invention, which is a specific configuration of the 14th to 17th embodiments, the liquid-liquid extraction is carried out at a temperature of 20° C. to 40° C., preferably 25° C. to 35° C., and particularly at room temperature.

[0053] In a nineteenth embodiment of the present invention, which is a further specific configuration of the eleventh to thirteenth embodiments, the isocyanate component comprises methylene diphenylene diisocyanate ("monomeric MDI" having two isocyanate groups; mMDI) or a mixture of methylene diphenylene diisocyanate and polymethylene polyphenylene polyisocyanate ("polymeric MDI" having three or more isocyanate groups; pMDI), and the extractant comprises (i) an organic solvent selected from (aliphatic or aromatic) hydrocarbons or halogen-substituted, in particular chlorinated, (aliphatic or aromatic) hydrocarbons, and (ii) hydrochloric acid.

[0054] In a twentieth embodiment of the present invention, which is a specific configuration of the nineteenth embodiment, the organic solvent (i) comprises a halogen-substituted, in particular chlorinated, (aliphatic or aromatic) hydrocarbon.

[0055] In a twenty-first embodiment of the present invention, which is a specific configuration of the twentieth embodiment, the halogen-substituted hydrocarbon is selected from methylene chloride, chloroform, chlorinated aromatic hydrocarbons (such as, in particular, chlorobenzene or ortho-dichlorobenzene), or a mixture of two or more of the aforementioned halogen-substituted hydrocarbons.

[0056] In the 22nd embodiment of the present invention, which is a specific configuration of the 19th to 21st embodiments, (III) extracting the first product phase with a halogenated hydrocarbon, followed by (IV) phase separation into a first aqueous phase and a first organic phase; (V) neutralizing the first aqueous phase and phase separating into a second aqueous phase and a second organic phase; (VI) Distilling and / or stripping the second organic phase to obtain an amine, in this embodiment methylene diphenylene diamine ("monomeric MDA" having two amino groups; mMDA) or a mixture of methylene diphenylene diamine and polymethylene polyphenylene polyamine ("polymeric MDA" having three or more amino groups; pMDA).

[0057] In a twenty-third embodiment of the present invention, which is a specific configuration of the nineteenth to twenty-second embodiments, the second product phase is purified by distillation and / or stripping to obtain a polyol.

[0058] In a 24th embodiment of the present invention, which is a specific configuration of the 19th to 23rd embodiments, the liquid-liquid extraction is carried out at a temperature of 20°C to 60°C, preferably 40°C to 55°C, more preferably 47°C to 53°C, and particularly preferably 50°C.

[0059] In a twenty-fifth embodiment of the invention, which can be combined with all other embodiments, the polyurethane product is a polyurethane foam.

[0060] The above briefly outlined embodiments of the present invention and possible further configurations are elucidated in more detail below. All the above embodiments and the below further configurations of the present invention can be combined together as desired, unless the contrary is clearly visible from the context or explicitly stated to the skilled person.

[0061] Preparation of polyurethane foam for chemical recycling Step (A) of the method of the present invention involves providing a polyurethane product to be chemically recycled in preparation for chemical decomposition.

[0062] This can in principle be any type of polyurethane product, but polyurethane foam is preferred.In the case of polyurethane foam, it is possible to process either flexible foam (e.g. from old mattresses, cushioned furniture or car seats) or rigid foam (e.g. from insulation) by the method of the present invention (also see the examples in this respect).Such polyurethane foams are usually produced using pentane, dichloromethane and / or carbon dioxide as blowing agent.

[0063] In addition, with regard to the isocyanate component, preference is given to polyurethane products based on isocyanates selected from (i) tolylene diisocyanate (TDI), (ii) methylene diphenylene diisocyanate (= "diisocyanate of the diphenylmethane series", mMDI; prepared from methylene diphenylene diamine, mMDA), (iii) a mixture of methylene diphenylene diisocyanate (mMDI) and polymethylene polyphenylene polyisocyanate (= "polyisocyanate of the diphenylmethane series", pMDI; prepared from polymethylene polyphenylene polyamine, pMDA), (iv) pentane 1,5-diisocyanate (PDI), (v) hexamethylene 1,6-diisocyanate (HDI), (vi) isophorone diisocyanate (IPDI), (vii) xylylene diisocyanate (XDI) or (viii) a mixture of two or more of the abovementioned isocyanates. Particularly preferred are polyurethane foams based on either TDI or MDI for the isocyanate component.

[0064] With regard to the polyol component, polyurethane foams based on a polyol selected from polyether polyols, polyester polyols, polyether ester polyols, polyether carbonate polyols, polyacrylate polyols, or a mixture of two or more of the above mentioned polyols are preferred. The polyol component is preferably a polyether polyol. More preferably, the polyol component is a polyether polyol (i.e., it does not contain any polyol other than polyether polyols, but includes a mixture of two or more different polyether polyols without departing from the scope of this embodiment). The polyether polyol may be filled with styrene-acrylonitrile copolymers (SAN copolymers). It is one of the advantages of the present invention that it is also applicable to such polyol components. A problem in the chemical degradation of polyurethane foams with a polyol component based on SAN copolymer-filled polyether polyols is that the SAN copolymer is released as fine polymer particles during the chemical degradation. This is true regardless of the chemical degradation method selected. The SAN polymer present as fine polymer particles in the reaction mixture causes problems in subsequent separation, for example by extraction methods. Furthermore, the fineness of the polymer particles makes filtration almost impossible, as the filters would quickly become clogged and no further removal would be possible.The advantage of the hydroaminolysis of the present invention is that after being released from the polyether polyol, the SAN polymer is partially converted back to a soluble form by a hydrolysis step, and therefore the reaction mixture can be easily worked up by extraction after chemical degradation.

[0065] Most preferably, the polyurethane product is one in which the isocyanate component is either tolylene diisocyanate (TDI) or methylene diphenylene diisocyanate (mMDI) or a mixture of mMDI and polymethylene polyphenylene polyisocyanate (pMDI) and the polyol component contains a polyether polyol (in particular a polyether polyol, i.e. no further polyols other than the polyether polyol, although mixtures of two or more different polyether polyols are included and do not depart from the scope of this embodiment).

[0066] Preferably, step (A) further comprises a preparatory step for the cleavage of the urethane bonds in step (B), which is in particular the mechanical grinding of the polyurethane product. Such preparatory steps are known to those skilled in the art, see, for example, "Freezing" the polyurethane product before mechanical grinding, depending on the properties of the polyurethane product, in order to facilitate the grinding operation. This is particularly true for polyurethane foams.

[0067] It is also conceivable that the above preparation step is carried out at a location that is spatially separated from the site of chemical decomposition. In that case, the prepared polyurethane product is transferred to a suitable transport vehicle, for example a silo vehicle, for further transportation. For further transportation, the prepared polyurethane product, especially in the case of polyurethane foam, may be additionally compressed to achieve a higher mass-to-volume ratio. The polyurethane product is then transferred to a reactor prepared for chemical decomposition at the site of chemical decomposition. It is also conceivable that the transport vehicle used is directly connected to the reactor.

[0068] Chemical degradation of polyurethane products to obtain chemical degradation products Step (B) of the method of the present invention involves chemical degradation of the polyurethane product provided in step (A).

[0069] The chemical decomposition is preferably carried out in the absence of oxygen. This means that the reaction is carried out in an inert gas atmosphere (particularly nitrogen, argon or helium atmosphere). It is also preferable to remove oxygen from the chemical decomposition reagents used (water and amine chemical decomposition reagents) by inert gas saturation.

[0070] As already mentioned, it is not necessary to add all the water just at the beginning of step (B). In particular, in step (B): (I) first mix the polyurethane product with either (1) the amine chemical decomposition reagent but not yet with water, or (2) the amine chemical decomposition reagent and a first portion of the water, and only thereafter (II) It is also possible to add the water (1) or the second portion of the water (2), especially once the polyurethane product has gone into solution.

[0071] Here, it is possible and preferred to add the catalyst already in step (I). Alternatively, it is possible to add the catalyst only in step (II), in particular as an aqueous catalyst solution, to the polyurethane product, in particular after the polyurethane product has gone into solution. The expression "into solution" in this context does not necessarily imply the presence of a "true" solution, in the sense of a completely homogeneous mixture. It is quite possible that a "turbid" solution of the polyurethane product is present. This does not depart from the scope of the present invention.

[0072] In the course of carrying out step (B) in steps (I) and (II), it is particularly preferred to add water (1) or the second portion of water (2) continuously or in small portions in step (II) so that the temperature of the liquid phase in step (II) differs from the temperature of the liquid phase in step (I) by at most 20°C, preferably at most 15°C, more preferably at most 10°C, even more preferably at most 5.0°C, very exceptionally preferably at most 1.0°C. A temperature always sufficiently high to ensure the progress of the chemical decomposition is thereby achieved. If a portion of water is already added at the beginning of the chemical decomposition (=(I)(2)), it is preferred that the first portion of water is at most 4.0% by mass, in particular 2.0% to 4.0% by mass, of the total amount of water added in step (B) (i.e. (I) and (II) combined).

[0073] Regardless of the exact configuration of step (B), it is preferred to use an aliphatic amine chemical decomposition reagent, which to this end is preferably (a) an aliphatic primary or secondary organic amine, (b) an aliphatic amino alcohol bearing a primary or secondary amino group, or (c) a mixture of the two.

[0074] The primary or secondary amines are preferably monoamines and / or diamines. Ethanolamine (2-aminoethanol), N-methylethanolamine, 3-amino-1-propanol, ethylene-1,2-diamine, 1,4-diaminobutane, hexamethylene-1,6-diamine or a mixture of two or more thereof are particularly preferred as amine chemical decomposition agents.

[0075] Preferred catalysts for carrying out the chemical decomposition are 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 (=tin(II) 2-ethylhexanoate)), zinc compounds (especially zinc acetate), carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrogen orthophosphates (especially alkali metal or alkaline earth metal monohydrogen orthophosphates), metaphosphates (especially alkali metal or alkaline earth metal metaphosphates) or a mixture of two or more of the abovementioned catalysts. Particularly preferred are carbonates (especially alkali metal or alkaline earth metal carbonates), orthophosphates (especially alkali metal or alkaline earth metal orthophosphates), monohydrogen orthophosphates (especially alkali metal or alkaline earth metal monohydrogen orthophosphates) or mixtures of two or more of the abovementioned catalysts. The weight ratio of catalyst to polyurethane product is preferably in the range of 0.001 to 0.035.

[0076] Suitable reactors for carrying out the chemical decomposition (=chemical decomposition reactors) are, for example, stirred tanks and tubular reactors. Stirred tanks are preferably designed as heatable jacketed stirred tanks. They have in particular a base outlet, a stirrer that can be controlled by a drive means, an inlet for filling solids, a supply pipe for liquid connected to a metering pump, and a sparging pipe for protective gas.

[0077] As already mentioned, the process of the present invention allows the chemical decomposition in step (B) to be carried out in a single reactor. However, in the embodiment further outlined above, which includes partial steps (I) and (II), especially in the case of a continuous process regime, it may be desirable to carry out step (I) (the step of "dissolving" the polyurethane product in an amine chemical decomposition reagent, optionally in the presence of a portion of water) and step (II) (the step of adding water or a portion thereof) in two consecutive reactors, which together constitute a chemical decomposition reactor. The above-mentioned preferred reactors can also be used here, but it is also possible to use a stirred tank in step (I) and a tubular reactor in step (II) (or vice versa).

[0078] Post-treatment of chemical decomposition products By the process (B), at least one amine corresponding to the isocyanate of the isocyanate component; (At least) one polyol (derived from the polyol component or formed from the polyol component in step (B)); an amine chemolysis reagent (used superstoichiometrically and therefore incompletely converted); Water (used superstoichiometrically and therefore incompletely converted) Chemical decomposition products containing

[0079] In step (C), the chemical decomposition products are post-treated to recover the raw materials, which may include recovering (at least) one amine, (at least) one polyol, or both.

[0080] Preferably, step (C) comprises liquid-liquid extraction with an extractant and phase separation into a first product phase comprising the amine or a salt of the amine and a second product phase comprising the polyol (separation of the amine and the polyol).

[0081] In a particular configuration of this embodiment, which is particularly advantageous when the polyurethane product is an MDI-based polyurethane product or a polyurethane product containing a mixture of different polyols in the parent polyol component, the liquid-liquid extraction is preceded by a distillative separation of the amine chemical decomposition reagent from the chemical decomposition products. After the amine chemical decomposition reagent is separated, a product mixture remains which is subjected to liquid-liquid extraction. In each case, the mass ratio of the mixture to be extracted (i.e. the product mixture obtained by distillative removal of the chemical decomposition products or the amine chemical decomposition reagent) to the extractant in the liquid-liquid extraction is preferably 0.5 to 1.5, more preferably 0.7 to 1.3, even more preferably 0.9 to 1.1, in particular 1.0. It is clear to the skilled person that this separation does not necessarily have to proceed completely in the sense that all the amine enters the first product phase and all the polyol enters the second product phase. For example, if a small amount of the amine enters the second product phase (or a small amount of the polyol enters the first product phase) as a result of the general solubility equilibrium, this naturally does not depart from the scope of the present invention.

[0082] A preferred field of use of the process according to the invention is the recycling of tolylene diisocyanate-based (TDI-based) polyurethane products, preferably TDI-based polyurethane foams, in particular flexible foams, in which the extractant is (i) an organic solvent selected from (aliphatic or aromatic) hydrocarbons or halogen-substituted, in particular chlorinated, (aliphatic or aromatic) hydrocarbons; (ii) water; It is preferred that the compound contains

[0083] Suitable organic solvents are in particular cyclohexane, toluene, methylene chloride, chloroform, chlorinated aromatic hydrocarbons (in particular chlorobenzene or ortho-dichlorobenzene, etc.) or a mixture of two or more of the aforementioned organic solvents. The liquid-liquid extraction is preferably carried out at a temperature of 20° C. to 40° C., preferably 25° C. to 35° C., in particular at room temperature.

[0084] The amine, in this case tolylenediamine (TDA), can be obtained from the first product phase by distillation, obtaining TDA as a purified distillate. The distillation of TDA is sufficiently well known in the art that it is not necessary to describe it in detail here.

[0085] The second product phase is purified, preferably by distillation and / or stripping, to obtain the polyol. In the stripping, a stripping gas is used, in particular nitrogen or steam, preferably nitrogen. The distillation is preferably carried out in an evaporator selected from falling film evaporators, thin film evaporators, flash evaporators, rising film evaporators, natural circulation evaporators, forced circulation evaporators or tank evaporators. It is particularly preferred that the distillation is followed by a stripping operation with steam.

[0086] A further preferred field of use of the method according to the invention is the recycling of MDI-based polyurethane products, i.e. polyurethane products whose isocyanate component is based on methylene diphenylene diisocyanate ("monomeric MDI" with two isocyanate groups; mMDI) or, preferably, on a mixture of methylene diphenylene diisocyanate and polymethylene polyphenylene polyisocyanate ("polymeric MDI" with three or more isocyanate groups; pMDI). Particular mention should be made here of MDI-based polyurethane foams, in particular rigid foams. The MDI-based polyurethane foams are preferably based on a mixture of mMDI and pMDI.

[0087] Whether or not the MDI-based polyurethane product is a foam, and whether the isocyanate component used in the manufacture of the polyurethane product contains only mMDI or a mixture of mMDI and pMDI, the extractant is (i) an organic solvent selected from (aliphatic or aromatic) hydrocarbons or halogen-substituted, in particular chlorinated, (aliphatic or aromatic) hydrocarbons; (ii) hydrochloric acid; It is preferred that the compound contains

[0088] Suitable organic solvents are in particular halogenated, in particular chlorinated (aliphatic or aromatic) hydrocarbons. Particular mention should be made here of methylene chloride, chloroform, chlorinated aromatic hydrocarbons (in particular chlorobenzene or ortho-dichlorobenzene, etc.) or mixtures of two or more of the abovementioned halogenated hydrocarbons. The liquid-liquid extraction is preferably carried out at temperatures between 20°C and 60°C, preferably between 40°C and 55°C, more preferably between 47°C and 53°C, in particular at 50°C.

[0089] Hydrochloric acid, in particular, must be used in an amount sufficient to protonate all primary or secondary amino groups present (a molar ratio of HCl to the sum of primary and secondary amino groups of at least 1:1). The ratio of primary to secondary amino groups can be determined by the amine number.

[0090] The amine value indicates how many milligrams of potassium hydroxide are required to neutralize the free organic amines present in 1 g of a substance. It covers primary, secondary and tertiary amino groups. Amino groups are weak bases. The solvent used is concentrated acetic acid (glacial acetic acid, 99% to 100%). The amines are protonated by the solvent and converted to the corresponding acids, which are now present as ion pairs with the deprotonated acids of glacial acetic acid. The mixture is subsequently titrated with 0.1 moles of perchloric acid as titrant, in the process replacing the anions of the solvent (glacial acetic acid). The perchloric acid consumed during the process is equal to the consumption of potassium hydroxide. The amine value is usually reported in milligrams of KOH per gram of sample analyzed and is calculated as follows: AZ / (mg(KOH) g -1 )=(V / ml·[b i / (mol l -1 )]·[M(KOH) / (g·mol -1 )]·f) / (m / g) Where: AZ represents the amine number, V represents the volume of perchloric acid solution consumed, m represents the mass of the titration sample, M(KOH) is the molar mass of KOH (56.11 g mol -1 ), b i is the molar concentration of the perchloric acid solution, f represents the dimensionless coefficient (titer amount) of the perchloric acid solution.

[0091] In the case of MDI-based polyurethane products, the work-up of the first product phase to obtain amines, i.e. in this case methylenediphenylenediamines ("monomeric MDA" having two amino groups; mMDA) or mixtures of methylenediphenylenediamines and polymethylenepolyphenylenepolyamines ("polymeric MDA" having three or more amino groups; pMDA), comprises in a particularly preferred embodiment the following further steps: (I) extracting the first product phase with a halogenated hydrocarbon, followed by (II) phase-separating the extraction process product into a first aqueous phase (containing the hydrochloride salt of mMDA, or the hydrochlorides of mMDA and pMDA) and a first organic phase; (III) neutralizing the first aqueous phase and phase separating into a second aqueous phase (containing salts formed in the neutralization) and a second organic phase (containing mMDA or mMDA and pMDA); (IV) The second organic phase is distilled and / or stripped to obtain the amine, which in this embodiment is mMDA or a mixture of mMDA and pMDA.

[0092] The work-up of the second product phase to obtain the polyol is preferably carried out by distillation and / or stripping as in the case of the TDI-based polyurethane products, the preferred configurations being the same as those described above.

[0093] The following examples are intended to further illustrate the invention. EXAMPLES

[0094] Example 1: 200 g of ethanolamine and 2 g of sodium carbonate are initially charged into a 1000 ml 4-neck flask equipped with a stirrer, thermometer and cooling assembly and heated to 150° C. under nitrogen. 200 g of rigid PU foam with the composition reported in Table 1 is added and dissolved under stirring. After dissolution, the mixture is stirred at 150° C. for 2 hours, after which 17 g of water is added over 30 minutes so that the reaction temperature does not fall below 150° C. After the addition of water, stirring is continued at 150° C. for 3 hours. The ethanolamine is then distilled off at 150° C. and below 20 mbar.

[0095] TIFF2024544908000002.tif98170

[0096] Examples 3 to 7: Further experiments were carried out using different amino alcohols and amines but otherwise the same procedure as in Example 1. The chemical degradation reagents used are summarized in Table 2.

[0097] TIFF2024544908000003.tif84170

[0098] Example 8: Example 8 corresponds to Example 1, except that ethanolamine, water and catalyst were directly charged first, and the reaction was carried out at 150° C. for 4 hours after the rigid PU foam in Table 1 was dissolved.

[0099] Example 9: Example 9 corresponds to Example 8, except that the foam in Table 1 was dissolved in ethanolamine before the catalyst and water were added. The reaction was then carried out at 150° C. for 4 hours.

[0100] Example 10: (Not the invention: too little water) 150 g of ethanolamine and 3 g of 50% aqueous sodium hydroxide solution are initially charged into a 500 ml four-neck flask equipped with a stirrer, thermometer and cooling assembly and heated to 150° C. under nitrogen. 150 g of rigid PU foam with the composition reported in Table 1 is added and dissolved under stirring. After dissolution, the mixture is stirred at 150° C. for 4 hours. The ethanolamine is then distilled off at 150° C. and below 20 mbar.

[0101] Example 11 (Invention: additional water added compared to Example 10) 150 g of ethanolamine and 3 g of 50% aqueous sodium hydroxide solution are initially charged into a 500 ml four-neck flask equipped with a stirrer, thermometer and cooling assembly and heated to 150° C. under nitrogen. 150 g of rigid PU foam with the composition reported in Table 1 is added and dissolved under stirring. After dissolution, the mixture is stirred at 150° C. for 2 hours, after which 14 g of water is added within 30 minutes so that the reaction temperature does not fall below 150° C. After the addition of water, stirring is continued at 150° C. for 3 hours. The ethanolamine is then distilled off at 150° C. and below 20 mbar.

[0102] TIFF2024544908000004.tif78170

[0103] The results show that ethanolamine and N-methylethanolamine are the most effective in terms of urethane cleavage and release of MDA and (P)MDA. N,N-disubstituted (tertiary)ethanolamines (Examples 3 and 5), in which the amino group cannot play a role in chemically cleaving the urethane bond, give significantly worse results.

[0104] Example 12: Further aminohydrolysis experiments were performed on flexible foams. Table 4 contains the flexible foam formulations used.

[0105] TIFF2024544908000005.tif78170

[0106] 300 g of ethanolamine and 3 g of sodium carbonate are initially charged into a 1000 ml four-neck flask equipped with a stirrer, thermometer and cooling assembly and heated to 150° C. under nitrogen. 300 g of flexible PU foam having the composition reported in Table 4 is added and dissolved under stirring. After dissolution, the mixture is stirred at 150° C. for 2 hours, after which 18 g of water is added within 30 minutes to prevent the reaction temperature from dropping below 150° C. After the addition of water, stirring is continued at 150° C. for 3 hours.

[0107] Example 13: Recovery of r-polyether polyol Polyether polyol was recovered from the reaction mixture resulting from Example 12 as follows ("r-polyether polyol").

[0108] The reaction mixture was mixed with 3 parts by weight of cyclohexane and vigorously homogenized. The mixture was separated in a separatory funnel into two phases: an organic cyclohexane-polyether phase (containing small amounts of TDA and ethanolamine) and an ethanolamine-TDA phase. The organic phase was separated and the solvent was removed by distillation to recover the r-polyol.

[0109] The OH number of the r-polyether polyol was 64.8 mg(KOH) / g, the amine number was 16.9 mg(KOH) / g. On the laboratory scale, it is not always possible to completely distill off the excess ethanolamine used and the TDA released during the chemical decomposition, which is reflected in the amine number of 16.9 mg(KOH) / g. The OH number of the r-polyether polyol, corrected by the amine number, is 47.9 mg(KOH) / g and is therefore within the range of 46 mg(KOH) / g to 50 mg(KOH) / g specified for fresh Arcol 1108. It can be assumed that the amines will be separated significantly better on an industrial scale using efficient distillation equipment.

[0110] The OH number (OHN) of the recovered r-polyether polyols was determined by titration. This involves acetylating the sample with acetic anhydride in the presence of pyridine. One mole of acetic acid is formed per hydroxyl group, and excess acetic anhydride results in 2 moles of acetic acid. The consumption of acetic acid is determined by titration from the difference between the main value and the blank value carried out simultaneously. The hydroxyl number is calculated taking into account the ml consumption of 0.5N potassium hydroxide solution in the main test and in the blank test, as well as the acid number (AN) and the starting weight of the sample, as follows: OHZ / (mg(KOH)·g -1 )=((V b -V a ) / ml·28055) / (m / g)+SZ / (mg(KOH)·g -1 ) Where: V a represents the volume of 0.5N potassium hydroxide solution consumed in this test, V b represents the volume of 0.5N potassium hydroxide solution consumed in the blank test, m represents the mass of the titrated sample.

[0111] The acid value was determined by titration as well. The acid value indicates how many mg of KOH are required to neutralize the free fatty acids in 1 g of fatty acid. A suitable starting weight is weighed into a glass beaker, dissolved in approximately 100 ml of neutralizing ethanol, and titrated potentiometrically with sodium hydroxide solution to the end point. The acid value is determined as follows: SZ / (mg(KOH) g -1 )=(V / ml)·[M(KOH) / (g·mol -1 )]·[N / (mol l -1 )]·f / (m / g) Where: AN stands for acid number, V represents the volume of sodium hydroxide solution consumed, M(KOH) is the molar mass of KOH (56.11 g mol -1 ), N represents the normality of the sodium hydroxide solution, f is the dimensionless coefficient (titration amount) of sodium hydroxide solution, m represents the mass of the titrated sample.

Claims

1. 1. A method for recovering raw materials from a polyurethane product, comprising: (A) providing a polyurethane product based on an isocyanate component and a polyol component; (B) (i) a method for the preparation of a hydroxyl group-containing amine compound (a) comprising the steps of: (a) a primary organic amine or a secondary organic amine; (b) an amino alcohol having a primary amino group or a secondary amino group; or (c) a mixture of (a) and (b); and (ii) water, in the presence of (iii) a catalyst, at a temperature of 100°C to 195°C and 900 mbar. （ａｂｓ．） ~2000 mbar （ａｂｓ．） chemically decomposing the polyurethane product in a liquid phase at a pressure of 0.1 to 1.0 to obtain a chemical decomposition product; The mass ratio of (1) the amine chemical decomposition reagent and water to (2) the polyurethane product is in the range of 0.5 to 2.5, and the mass of the water is 3.0% to 22% of the mass of the amine chemical decomposition reagent; (C) post-treating the chemical decomposition products to obtain amines and / or polyols.

2. In step (B), the polyurethane product is (I) first (1) mixing with the amine chemical decomposition reagent but not yet with the water, or (2) mixing with the amine chemical decomposition reagent and a first portion of the water, and then 2. The method of claim 1, wherein (II) the water (1) or the second portion of the water (2) is added.

3. 3. The method according to claim 2, wherein in step (II), the water (1) or the second portion of water (2) is added continuously or in small portions so that the temperature of the liquid phase in step (II) differs by at most 20° C. from the temperature of the liquid phase in step (I).

4. 4. The method of any one of claims 1 to 3, wherein step (C) comprises liquid-liquid extraction with an extractant and phase separation into a first product phase comprising the amine or a salt of the amine and a second product phase comprising the polyol.

5. 5. The method of claim 4, wherein the liquid-liquid extraction is preceded by a distillative separation of the amine chemical degradation reagent from the chemical degradation products.

6. 5. The method of claim 4, wherein the isocyanate component comprises tolylene diisocyanate and the extractant comprises (i) an organic solvent selected from hydrocarbons or halogen-substituted hydrocarbons, and (ii) water.

7. 7. The method of claim 6, wherein the amine is distilled from the first product phase.

8. 5. The method of claim 4, wherein the isocyanate component comprises methylene diphenylene diisocyanate or a mixture of methylene diphenylene diisocyanate and polymethylene polyphenylene polyisocyanate, and the extractant comprises (i) an organic solvent selected from hydrocarbons or halogen-substituted hydrocarbons, and (ii) hydrochloric acid.

9. (I) extracting the first product phase with a halogen-substituted hydrocarbon, followed by (II) phase separation into a first aqueous phase and a first organic phase; (III) neutralizing the first aqueous phase and separating it into a second aqueous phase and a second organic phase; (IV) distilling and / or stripping the second organic phase to obtain an amine; The method of claim 8.