Polyurethane depolymerization process

Abstract

The present invention relates to a new and improved process for the depolymerization of polyurethanes, wherein polyether polyols and polyamines can be recovered in high yield.

Description

[0001] This invention relates to novel and improved methods for depolymerizing polyurethane, wherein polyether polyols and polyamines can be recovered in high yields.

[0002] Polyurethane is a material of considerable utility in the production of rigid and flexible foams, solid and microporous elastomers, sealants, coatings, and adhesives. The versatility, relatively low cost, and excellent performance of polyurethane have led to the rapid growth of the polyurethane industry over the past 50 years. Currently, thousands of tons of polyurethane are produced worldwide each year. Unfortunately, most polyurethanes are thermosetting materials that are cross-linked to some extent. Unlike thermoplastics such as polyethylene, polypropylene, and polystyrene, waste or scrap polyurethane cannot therefore be easily remelted or reprocessed into useful articles. Due to the strong desire, for both economic and environmental reasons, to reuse or recycle the large quantities of waste or scrap polyurethane generated annually, rather than burning or dumping it in landfills, considerable creative effort has been devoted to designing methods to recover useful chemical components from waste polyurethane materials.

[0003] Glycolysis is used for the recycling of PU (polyurethane) waste (including rigid and flexible types of products), i.e., depolymerization. The method requires multiple steps, such as (1) grinding, (2) stepwise addition of the waste to diethylene glycol in the presence of a catalyst, (3) alkoxylation, and (4) degassing and filtration to recover polyols.

[0004] Polyurethane foam waste can also be recycled via ammonolysis and ammonolysis methods by using ammonia, amines, or alkanolamines to recover monomeric polyols that can be reused in the synthesis of PU. For example, DE 102006036007A1 describes a method in which polyurethane and polyurea are recycled via ammonolysis.

[0005] Acid hydrolysis has also been suggested for recovering polyols. However, none of these methods have been used on a large industrial scale. They are too complex and expensive, requiring high temperatures and pressures, and the quality of the recovered polyols and amines is poor, so only small quantities can be used with large quantities of virgin raw materials to produce new polyurethane foam.

[0006] Hydrolysis methods for the depolymerization of polyurethanes have also been tested in the prior art. However, the known method of using base catalysis to hydrolyze polyurethanes to recover polyether polyols and polyamines has some drawbacks. At relatively low temperatures, the hydrolysis rate is slow, and correspondingly, the hydrolysis is reported to be incomplete. At higher temperatures, the rate is faster, but some undesirable side reactions may occur. For example, US 5,208,379 discloses a method for hydrolyzing polyurethanes prepared by reacting a hydrogen-containing polyether with an organic polyisocyanate, comprising contacting the polyurethane with water in the presence of an effective amount of a strong base selected from alkali metal oxides, alkali metal hydroxides, alkaline earth metal oxides, and alkaline earth metal hydroxides, and an effective amount of an activator selected from quaternary ammonium salts containing at least 15 carbon atoms and organic sulfonates containing at least 7 carbon atoms, for a time and temperature that effectively produces hydrogen-containing polyethers and organic polyamines. Although US 5,208,379 discloses in its general description that the reaction temperature can be selected in the range of 80°C to 225°C, Example 19 shows that only partial hydrolysis occurs at 120°C, and Example 18 shows that the yield is only 70% at 140°C. Therefore, the method of US 5,208,379 cannot be used economically at lower temperatures.

[0007] Therefore, there remains an urgent need to provide more effective methods for polyurethane recycling in order to recover polyether polyols and / or polyamines with high quality and high yield.

[0008] The subject of this invention is to provide a novel method for depolymerizing polyurethane, which overcomes the aforementioned defects of existing methods.

[0009] Another specific problem of the present invention is to provide a method that can operate at lower temperatures and has good yields compared with the prior art.

[0010] Another specific problem this invention aims to solve is to provide a method for obtaining polyether polyols and / or polyamines with a mass very close to that of the raw materials used to prepare recycled polyurethane. It should be possible to use recycled polyether polyols and / or polyamines in a high proportion to prepare new polyurethane.

[0011] Other problems solved by the present invention but not previously described are derived from the following description, embodiments and claims.

[0012] The inventors have surprisingly discovered a method for preparing polyurethane by hydrolysis, preferably by reacting an active hydrogen-containing polyether with an organic polyisocyanate, which can yield active hydrogen-containing polyethers, preferably polyether polyols, and organic polyamines in high yields. The method comprises contacting the polyurethane with water in the presence of a strong inorganic base and a quaternary ammonium salt containing an ammonium cation, wherein the strong inorganic base has a pK... bIf the value is less than 1, the ammonium cation contains 6 to 14 carbon atoms if the ammonium cation does not contain a benzyl residue, or contains 6 to 12 carbon atoms if the ammonium cation contains a benzyl residue.

[0013] What is particularly surprising is that, contrary to the teachings of US5,208,379, ammonium cations with a lower number of carbon atoms lead to higher yields at lower reaction temperatures.

[0014] The recovered hydrogen-containing polyethers and / or organic polyamines of this invention exhibit excellent quality and can be used in high proportions to prepare novel polyurethane foams. Even when using 100% of the hydrogen-containing polyethers of this invention to prepare novel polyurethane foams, high-quality polyurethane foams can be obtained. Unbound by any theoretical constraints, the inventors believe that, under specific mild reaction conditions, the method of this invention avoids the formation of potentially problematic byproducts during polyurethane preparation.

[0015] Therefore, one embodiment of the present invention is a method for hydrolyzing polyurethane. Another embodiment is the use of the recovered hydrogen-containing polyethers, preferably polyether polyols, and / or organic polyamines of the present invention in the preparation of polyurethanes, particularly polyurethane foams.

[0016] Before describing the invention in more detail, some important terms are defined as follows:

[0017] The verb “comprising” and its variations, as used in the specification, embodiments, and claims, are used in a non-limiting sense to mean that the items following the word are included, but do not exclude items not specifically mentioned. “Comprising” includes “consisting of”, which means that, as a preferred embodiment, the items following the word “comprising” are included, but not any additional, unspecific items are excluded.

[0018] Using the indefinite articles "a" or "an" to refer to an element does not preclude the possibility that there is more than one element, unless the context explicitly requires the presence of one and only one element. Therefore, the indefinite articles "a" or "an" generally mean "one or more".

[0019] The terms “catalyst” and “activator” are used synonymously in this invention.

[0020] In the context of this invention, polyurethane (PU) is specifically understood to refer to products obtained by reacting polyisocyanates with polyols or compounds having isocyanate reactive groups. Polyurethanes suitable for use in the methods of this invention are those prepared from polyethers containing active hydrogen and polyisocyanates. This type of polyurethane is well known and described, for example, in Ulrich, "Urethane Polymers," Encyclopedia of Chemical Technology, Vol. 23, pp. 576-608 (1983) and Backus et al., "Polyurethanes," Encyclopedia of Polymer Science and Technology, Vol. 13, pp. 243-303 (1988). Any known polyurethane can be used in the methods of this invention.

[0021] Polyethers containing active hydrogen are preferably polyether polyols (i.e., polyethers with primary and / or secondary terminal groups, preferably hydroxyl groups), but can also be amine-functionalized polyethers (e.g., "Jeffamine" polyoxypropylene sold by Texaco Chemical Co.). Such materials are typically prepared by catalytic ring-opening polymerization of one or more cyclic ethers such as epoxides, oxolanes, or oxolanes. Initiators with two or more active hydrogens, such as polyols, amines, or acids, can be used to vary the functionality (number of active hydrogens) of the polyether. If more than one type of cyclic ether is used, they can react simultaneously (to obtain random copolymers) or sequentially (to obtain block copolymers). Exemplary cyclic ethers include propylene oxide, ethylene oxide, butane oxide, tetrahydrofuran, and oxolanes. Examples of suitable hydrogen-containing polyethers include polypropylene glycol, polyethylene glycol, polytetramethylene glycol, polytrimethylene glycol, ethylene oxide-terminated polypropylene glycol, and random copolymers of ethylene oxide and propylene oxide.

[0022] The structure of the active hydrogen-containing polyether, preferably the polyether polyol, recovered in the method of the present invention is related to the structure of the polyether polyol used to prepare the polyurethane to be treated in the method of the present invention.

[0023] The structure of the polyamine recovered in the method of the present invention is related to the structure of the polyisocyanate used to prepare the polyurethane to be treated in the method of the present invention. The term "polyamine" as used in the present invention includes diamines, and preferably includes amines having two or more primary amino groups in the molecule.

[0024] The polyurethane used in the method of this invention can be derived from any polyisocyanate reactant (i.e., an organic compound containing two or more isocyanate groups). Suitable polyisocyanates include, but are not limited to, aliphatic diisocyanates, alicyclic diisocyanates, arylalkyl diisocyanates, aromatic diisocyanates (e.g., toluene diisocyanate and diphenylmethane diisocyanate), aromatic triisocyanates, and mixtures of isocyanates, such as isocyanates commonly referred to as "PMDI". Modified, masked, or blocked polyisocyanates can also be used.

[0025] The polyurethane used in the methods of this invention may also include any conventional additional reactants or additives known in the art, such as chain extenders or curing agents (relatively low molecular weight active hydrogen-containing compounds such as glycols and diamines or polyamines), physical or chemical foaming agents, flame retardants, surfactants, fillers, stabilizers, antioxidants, colorants, polymers other than polyurethane polymers (e.g., styrene-acrylonitrile copolymers, such as those found in polymeric polyols), catalysts, such as catalysts that promote gelation reactions (isocyanate-polyol), foaming reactions (isocyanate-water), and / or dimerization or trimerization of isocyanates. The polyurethane may be in solid, microporous, or foam form, and may be a material ranging from rubber, elastomers, and soft materials to rigid substances.

[0026] To facilitate the handling of polyurethane, it is preferable to shred, crush, grind, or divide it into relatively small particles or granules. If the polyurethane is a foam, it can be partially or completely compressed before contact with water, strong alkalis, and activators. If the polyurethane is in solid form, an initial shredding step is highly advantageous to maximize the surface area available for the reaction (thus reducing the reaction time required to reach the desired level of hydrolysis).

[0027] The method of the present invention will result in the effective hydrolysis and cleavage of urethane and urea bonds present in the treated polyurethane to produce polyethers containing active hydrogen, preferably polyether polyols, polyamines, and if the polyurethane is prepared using a chain extender or curing agent, low molecular weight glycols, diols, and diamines will be produced.

[0028] The alkali used in this invention is pK at 25°C. b The value is less than 1, preferably 0.5 to -2, more preferably 0.25 to -1.5, and most preferably 0 to -1, of a strong inorganic base. The inorganic base is a base that does not contain CH bonds.

[0029] Particularly preferred is the strong base selected from alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides, and mixtures thereof. Preferred alkali metals are selected from Na, K, and Li, and mixtures thereof, with the most preferred selection being Na and K, and mixtures thereof. Preferred alkaline earth metals are selected from Be, Mg, Ca, Sr, Ba, and mixtures thereof, with the most preferred selection being Mg and Ca, and mixtures thereof. Most preferably, an alkali metal selected from potassium or sodium, and mixtures thereof is used.

[0030] Compared with existing methods, the method of the present invention can be operated at a higher yield at a lower temperature using the above-mentioned alkali, thus significantly helping to reduce operating costs.

[0031] The amount of alkali in the reaction mixture must be sufficient to catalyze the desired hydrolysis of the polyurethane at a feasible rate. Preferably, the weight ratio of alkali to polyurethane is 0.01 to 25, more preferably 0.1 to 15, even more preferably 0.2 to 10, and most preferably 0.5 to 5. The alkali is preferably used in the form of an alkaline solution comprising alkali and water. For efficient conversion, it is particularly preferred that the concentration of alkali in the alkaline solution is greater than or equal to 5% by weight, preferably 5 to 70% by weight, more preferably 5 to 60% by weight, even more preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight, and most preferably 20 to 40% by weight.

[0032] Quaternary ammonium salts are used as phase transfer catalysts in the methods of the present invention. Although adding even trace amounts of these catalysts will accelerate the hydrolysis rate, it is preferred to use at least 0.5% by weight, more preferably 0.5 to 15% by weight, even more preferably 1 to 10% by weight, particularly preferably 1 to 8% by weight, especially preferably 1 to 7% by weight, and most preferably 1 to 6% by weight of the catalyst based on the weight of the polyurethane.

[0033] The quaternary ammonium salts that can be used in this invention include those organic nitrogen-containing compounds, wherein the molecular structure includes a centrally positively charged nitrogen atom, i.e., an ammonium cation, attached to four organic (i.e., hydrocarbon) groups, and a negatively charged anion, such as a halide ion, preferably a chloride ion, a bromide ion, a bisulfate ion, an alkyl sulfate ion, preferably a methyl sulfate ion and an ethyl sulfate ion, a carbonate ion, a bicarbonate ion, a carboxylate ion, preferably an acetate ion, or a hydroxide ion.

[0034] Quaternary ammonium salts are well known and described, for example, in Cahn et al., "Surfactants and Defensive Systems", Encyclopedia of Chemical Technology, 3rd edition, Vol. 22, pp. 383-385 (1983) and Catonic Surfactants, E. Jungermann, Ed., Marcel Dekker, New York (1970), pp. 1-173. Many such compounds are commercially available at relatively low cost.

[0035] It has been found that the most efficient method in this invention is a quaternary ammonium salt containing an ammonium cation, which contains a total of 6 to 14 carbon atoms if the ammonium cation does not contain a benzyl residue, and contains 6 to 12 carbon atoms if the ammonium cation contains a benzyl residue. Contrary to the teachings of US 5208379, the inventors have found that if an ammonium cation with a higher number of carbon atoms is used at the same reaction temperature, the yield is significantly reduced. The same applies if the number of carbon atoms is less than 6.

[0036] The catalyst that has been proven to be highly efficient and is therefore preferred for use in the methods of the present invention is a quaternary ammonium salt having the general formula R1R2R3R4NX, wherein R1, R2, R3 and R4 are the same or different and are hydrocarbon groups selected from alkyl, aryl and arylalkyl, and X is selected from halide ions, preferably chloride and / or bromide ions, bisulfate ions, alkyl sulfate ions, preferably methyl sulfate and ethyl sulfate ions, carbonate ions, bicarbonate ions, carboxylate ions, preferably acetate ions, or hydroxide ions.

[0037] Preferably

[0038] R1 to R3 may be the same or different, and are alkyl groups having 1 to 6, preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1 carbon atom, wherein the alkyl group may be straight-chain, branched, cyclic, saturated or unsaturated, and most preferably straight-chain, saturated alkyl group.

[0039] -R4 is selected from alkyl groups having 3 to 11, preferably 3 to 10, more preferably 3 to 8, and most preferably 4 to 6 carbon atoms; aryl groups having 6 to 11, preferably 6 to 10, and most preferably 6 to 8 carbon atoms; and aralkyl groups having 7 to 11, preferably 7 to 10, and most preferably 7 to 9 carbon atoms, wherein the alkyl group may be straight-chain, branched, cyclic, saturated, or unsaturated, and most preferably straight-chain, saturated alkyl groups.

[0040] -X is selected from halide ions, preferably chloride and / or bromide ions, bisulfate ions, alkyl sulfate ions, preferably methyl sulfate and ethyl sulfate ions, carbonate ions, bicarbonate ions, acetate ions, or hydroxide ions.

[0041] In a first preferred embodiment, the catalyst is a quaternary ammonium salt having the general formula R1R2R3R4NX, wherein R4 is different from a benzyl residue, and R1 to R4 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 6 to 14, preferably 7 to 14, more preferably 8 to 13.

[0042] In a second preferred embodiment, the catalyst is a quaternary ammonium salt having the general formula R1R2R3R4NX, wherein R4 is a benzyl residue, and R1 to R3 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 6 to 12, preferably 7 to 12, more preferably 8 to 11.

[0043] The most preferred quaternary ammonium salts suitable for use as activators in the methods of the present invention include benzyltrimethylammonium chloride and tributylmethylammonium chloride.

[0044] Preferably, in the method of the present invention, polyurethane reacts with water, alkali, and catalyst at a temperature of 80°C to 200°C, preferably 90°C to 180°C, more preferably 95°C to 170°C, and most preferably 100°C to 160°C. If the temperature is too low, the yield will be insufficient. From an economic point of view, excessively high temperatures are inefficient and may cause side reactions, forming unwanted byproducts.

[0045] Preferably, the polyurethane reacts with water, alkali and catalyst for 1 minute to 14 hours, more preferably 1 minute to 12 hours, more preferably 5 minutes to 12 hours, even more preferably 10 minutes to 11 hours, particularly preferably 20 minutes to 10 hours, especially preferably 20 minutes to 8 hours, and most preferably 20 minutes to 7 hours.

[0046] Although water acts as a reactant in the desired polyurethane hydrolysis reaction and therefore does not need to be present in stoichiometric excess relative to the urethane functional groups in the polymer to be hydrolyzed, it is generally desirable to use a large quantity of water so that it can be conveniently used as a reaction medium and solvent or carrier for strong bases and activators. For these reasons, water is preferably present in condensed (liquid) form. Typically, the weight ratio of polyurethane to water is 3:1 to 1:15.

[0047] Hydrolysis is preferably carried out at atmospheric pressure, although extra-atmospheric pressure may be used if necessary. Optionally, a solvent miscible or immiscible with water, such as an alcohol, ketone, ester, ether, amide, sulfoxide, haloalkanes, aliphatic or aromatic hydrocarbons, may be present in the reaction mixture to facilitate the hydrolysis process or aid in the recovery of reaction products.

[0048] The hydrolysis reaction can be carried out in any suitable container or other equipment (e.g., stirred tank reactor or screw extruder) in a batch, continuous or semi-continuous manner, thereby allowing the polyurethane to come into contact with water in the presence of an alkali and an activator. Stirring or agitation of the reaction components is generally preferred to ensure close contact, a rapid hydrolysis rate, and proper temperature control.

[0049] The polyethers, preferably polyether polyols, organic polyamines, chain extenders and curing agents produced during hydrolysis can be separated and recovered from the crude reaction mixture using any suitable method or combination of methods known in the art, such as extraction (e.g., using an organic solvent immiscible with water as an extractant), distillation, precipitation, and filtration.

[0050] The recovered hydrogen-containing polyethers, preferably polyether polyols, obtained in the method of this invention have excellent quality. The inventors have discovered that they can be used to prepare high-quality polyurethane foams even without the addition of the original polyether polyol. This is a significant improvement compared to prior art methods for polyurethane depolymerization.

[0051] The recovered polyamines can be converted into organic polyisocyanates using conventional methods and similarly used as components of polyurethanes.

[0052] Without further elaboration, it is believed that those skilled in the art can make full use of the invention using the foregoing description. Therefore, the following embodiments should be considered merely illustrative and not limiting of the claims or the remainder of this disclosure.

[0053] Examples 1-5 and Comparative Examples CE1 to CE6

[0054] A 25g compressed polyurethane foam block (approximately 1cm x 1cm) was placed into a reactor from Parr Instrument Company equipped with a PTFE liner and a mechanical stirrer, and 75g of alkaline aqueous solution was added. The catalyst was then added, the reactor was shut off, and the mixture was heated to the operating temperature. After the desired reaction time, the mixture was allowed to cool, the reactor was opened, and the reaction mixture was transferred to a round-bottom flask.

[0055] Remove the water and extract the remaining solid with cyclohexane. Wash the cyclohexane solution with 1N HCl aqueous solution, dry with magnesium sulfate and remove the solvent. After drying and removing the solvent, extract the solid with warm toluene to obtain the amine.

[0056] Table 1 shows the alkaline solutions and catalysts used, their amounts, reaction time and temperature, and the yields of recovered polyether polyols and amines.

[0057] Table 1

[0058]

[0059]

[0060] TBMAC = Tributylmethylammonium chloride (C=13)

[0061] BnTMAC = Benzyltrimethylammonium chloride (C = 10)

[0062] TBAHS = Tetrabutylammonium bisulfate (C=16)

[0063] Varioquat K1215 = Methylbis(polyethoxyethanol)cocoylammonium chloride (C>37)

[0064] Varisoft 137-90 = dimethyl di(C 14 –C 18 Alkyl)methylammonium sulfate (C>30)

[0065] Adogen 432CG = Dihexadecanyldimethylammonium chloride (C=34)

[0066] All comparative examples CE1 to CE6 meet the requirement of US 5208379, namely, that the ammonium cation has more than 15 carbon atoms. Conversely, in Examples 1 to 5 of the present invention, the ammonium cations have 10 and 13 carbon atoms, respectively, which is less than 15, and therefore fall outside the scope of US 5208379. The examples and comparative examples demonstrate that, under all reaction conditions, the method of the present invention yields better yields than the method of US 5208379.

[0067] Performance testing

[0068] Preparation of thermosetting flexible PU foam (flexible block foam)

[0069] For performance testing of recycled polyols, use the thermosetting flexible PU foam formulations specified in Table 2.

[0070] Table 2: Formulations for the preparation of thermosetting flexible PU foam.

[0071]

[0072]

[0073] 1) Polyol 1: Standard raw polyols available from Covestro 1104 is a glycerol-based polyether polyol with an OH value of 56 mg KOH / g and an average molar mass of 3000 g / mol, or a recycled polyol of the present invention or a recycled polyol not of the present invention. The recycled polyol is obtained through chemical recycling from flexible polyurethane foam. The recycled polyol of the present invention used in Example 2 is described.

[0074] 2) T9, available from Evonik Industries: tin(II) salt of 2-ethylhexanoic acid.

[0075] 3) DMEA: Dimethylethanolamine, available from Evonik Industries. An amine catalyst used in the preparation of polyurethane foam.

[0076] 4) Polyether-modified polysiloxanes are available from Evonik Industries.

[0077] 5) Toluene diisocyanate T 80 from Covestro (80% 2,4 isomer, 20% 2,6 isomer), 3 mPa·s, 48% NCO, functionality 2.

[0078] 6) EF, a zero-emission metal catalyst, is available from Evonik Industries: a tin(II) salt of ricinoleic acid.

[0079] 7) NE1050: Low-emission amine catalyst, available from Evonik Industries.

[0080] 8) Low-emission polyether-modified polysiloxanes with total cyclic siloxanes <0.03% by weight are available from Evonik Industries.

[0081] Preparation of recycled polyols

[0082] Recovered polyol 1 (not of this invention)

[0083] The non-inventive recycled polyol 1 was prepared according to the procedure published by H&S Anlagentechnik in 2012: https: / / www.dbu.de / OPAC / ab / DBU-Abschlussbericht-AZ-29395.pdf

[0084] 300.2 g of compressed polyurethane foam (approximately 1 cm × 1 cm) was loaded into a reactor from Parr Instruments equipped with a glass liner and a mechanical stirrer. According to Formulation 1 in Table 2, conventional polyols were used... 1104 is the polyurethane foam used in its preparation.

[0085] 152.64g of polyol 1104, 75.63 g of phthalic acid, and 11.97 g of hydrogen peroxide (30 wt% in water) were added to the foam block. The reaction mixture was heated to an internal temperature of 250 °C. The reaction was maintained at an internal temperature between 237 °C and 256 °C for 5 hours. After heating was stopped, 140.63 g of the second portion was added at 160 °C under a nitrogen atmosphere. 1104. The reaction mixture was decanted at 80°C and then cooled to room temperature. The cooled and decanted reaction mixture was used as recycled polyol 1, which is not part of this invention. This process was repeated to produce a sufficient quantity of recycled polyol for foaming experiments.

[0086] Recovery of polyol 2 (this invention)

[0087] The recovered polyol of the present invention used in Example 2.

[0088] General procedure for preparing foam samples

[0089] For each foaming test, use 300g of polyol; recalculate the other formulation components accordingly. For example, 1.00 part of a component is expressed as 1.00 g of the substance / 100 g of polyol.

[0090] Foaming was carried out in a so-called manual mixing process. Formula 1 or Formula 2 as specified in Table 2 was used. For this purpose, different polyols, corresponding amine catalysts, tin catalyst 2-ethylhexanoate tin(II), water, and foam stabilizers were added to paper cups and the contents were mixed for 60 seconds at 1000 rpm using a disc stirrer. After the first stirring, isocyanate (TDI) was added to the reaction mixture and stirred for 7 seconds at 2500 rpm, then the reaction mixture was immediately transferred to a paper-lined box (30 cm × 30 cm base area and 30 cm height). Upon pouring, the foam rose in the foam box. Ideally, the foam blew off upon reaching its maximum rising height and then slightly recoiled. This opened the pore membrane of the foam, resulting in an open-cell structure. Defined foam bodies were cut from the resulting thermosetting flexible PU foam blocks for further analysis.

[0091] Characterization of flexible PU foam:

[0092] The prepared flexible polyurethane foam was evaluated based on the following foam properties a) to l):

[0093] a) Settling (or sinking) of foam after the rising phase: Settling or further rising is observed from the difference in foam height between immediately after bursting and 3 minutes after bursting. Foam height is measured at its maximum position in the middle of the top of the foam using a needle fixed to a centimeter ruler. Positive values ​​describe settling of the foam after bursting; negative values ​​correspondingly describe further rising of the foam.

[0094] b) Foam height: The height of the freely rising foam that forms after 3 minutes. Foam height is reported in centimeters (cm).

[0095] c) Rise time: The time between the end of mixing of the reaction components and the rupture of the polyurethane foam.

[0096] Rise time is reported in seconds (s).

[0097] d) Porosity Measurement by Dynamic Pressure: The permeability of foam is determined by measuring the dynamic pressure of the foam according to DIN EN ISO 4638:1993-07. The measured dynamic pressure is reported in mmH2O, and lower dynamic pressure values ​​characterize more open foam. The measured values ​​are in the range of 0-300 mmH2O. Dynamic pressure is measured using a device including a nitrogen source, a pressure reducing valve with a pressure gauge, a flow regulating screw, a wash bottle, a flow meter, a T-shaped fitting, an applicator nozzle, and a graduated glass tube filled with water. The applicator nozzle has an edge length of 100×100 mm, a weight of 800 g, an inner diameter of 5 mm for the outlet opening, an inner diameter of 20 mm for the lower applicator ring, and an outer diameter of 30 mm for the lower applicator ring. Measurement is performed by setting the nitrogen inlet pressure to 1 bar and the flow rate to 480 l / h using the pressure reducing valve. The water volume in the graduated glass tube is set such that no pressure difference is generated and no reading is possible. For measurements taken on specimens measuring 250×250×50mm, the applicator nozzle is positioned at a corner of the specimen, flush with the edge, and in the (estimated) center of the specimen (on the side with the largest surface area in each case). Once a constant dynamic pressure is established, the results are read. The final result is calculated by averaging the five measurements obtained.

[0098] e) Number of cells per cm (cell count): This is determined visually on the cut surface (measured according to DIN EN 15702).

[0099] f) Compression hardness (CLD), 40%, according to DIN EN ISO 33861:1997+A1:2010. Measured values ​​are reported in kilopascals (kPa).

[0100] g) Constant deflection compressive permanent deformation (also known as compressive permanent deformation)

[0101] Cut five specimens, each measuring 5cm × 5cm × 2.5cm, from the finished foam. Measure the initial thickness. According to DIN EN ISO 1856 2018, measure the compression set no earlier than 72 hours after preparation. Place the specimens between the plates of the deformation apparatus and compress them to 90% of their thickness (i.e., to 2.5mm). Within 15 minutes, place the specimens in an oven at 70°C and leave them there for 22 hours. After this, remove the apparatus from the oven, remove the specimens from the apparatus within 1 minute, and place them on a wood surface. After a 30-minute relaxation period, measure the thickness again and calculate the compression set, reporting the result as a percentage of the original thickness: DVR = (d0 - dr) / d0 × 100%.

[0102] h) Tensile strength and elongation at break according to DIN EN ISO 1798:2008. Tensile strength measurements are reported in kilopascals (kPa), and elongation at break measurements are reported as a percentage (%).

[0103] i) Resilience according to DIN EN ISO 8307:2007. Measured values ​​are reported as a percentage (%).

[0104] j) Emission characteristics at room temperature according to DIN EN ISO 16000-9:2008-04. Here, these materials are characterized by the type and amount of organic matter they emit. This analytical method is used to determine the emissions from materials used in furniture and mattresses. This is achieved by measuring emissions at room temperature using a test chamber.

[0105] analyze

[0106] Sample preparation, sampling, and sample size

[0107] The reaction mixture was transferred to a box (30cm x 30cm base area and 30cm height) covered by a PE plastic bag with an open top. Upon pouring, the foam rose within the foam box. Ideally, the foam burst at its maximum height and then slightly recoiled. This opened the foam's pore membrane, resulting in an open-cell structure. After the foam rose and burst, the PE bag was closed 3 minutes later. The foam was stored at room temperature for 12 hours in this manner to allow for complete reaction while preventing premature VOC release. Subsequently, the PE bag was opened, and a 7cm x 7cm x 7cm cube was removed from the center of the foam block, immediately wrapped in aluminum foil, and hermetically sealed within the PE bag. This was then transported to the analytical laboratory, where the foam cube was introduced into a clean 30-liter glass test chamber. Conditions in the test chamber were controlled climatic conditions (temperature 21°C, humidity 50%). Half the test chamber volume was replaced every hour. After 24 hours, the sample was removed from the test chamber air. Tenax adsorption tubes were used to absorb the VOCs. The Tenax tube was then heated, and with the aid of an inert gas flow, the released volatile substances underwent cryofocusing in the cold trap of a temperature-programmable evaporator. After the heating phase and cryofocusing, the cold trap was rapidly heated to 280°C, and the condensed substances volatilized. They were subsequently separated in a gas chromatography column and detected by mass spectrometry. Using a reference material for calibration, a semi-quantitative assessment of emissions was possible, in μg / m³. 3 The quantitative reference substance used for VOC analysis (VOC value) is toluene. Signal peaks can be assigned to substances using mass spectrometry and retention indices. The following equipment is used for analysis: Gerstel, D-45473 Mühlheim an der Ruhr, Eberhard-Gerstel-Platz 1, Germany, TDS-3 / KAS-4. Desorption tube: Agilent Technologies 7890A(GC) / 5975C(MS); Column: HP Ultra2 (50m, 0.32mm, 0.52μm); Carrier gas: Helium. More detailed procedure instructions can be found in DIN EN ISO 16000-9:2008-04.

[0108] k) Odor testing of the obtained foam. The finished foam was packaged in odor-neutral plastic bags and stored under airtight conditions. For odor evaluation of the foam, cubes measuring 10cm × 10cm × 10cm were cut out and transferred to 1L containers. The odor of the sample was smelled from the container. The container was sealed with a screw cap. After storing the container at 22°C for 24 hours, the odor was tested. The odor test was evaluated by a group of 13 trained odor testers. They were asked about the intensity of the odor, with low odor levels rated as +, medium odor as ++, and high odor as +++.

[0109] l) Aldehyde emissions based on VDA275

[0110] In this method, a sample of a certain mass and size is fixed above distilled water in a sealed 1L glass bottle and stored at a constant temperature for a predetermined period of time. The bottle is then cooled, and the absorbed aldehydes are measured in the distilled water. The amount of aldehyde measured is based on the dry weight (mg / kg) of the foam sample.

[0111] After the foam was removed from the foam box, it was stored at 21°C and approximately 50% relative humidity for 24 hours. Samples were then collected from representative locations across the width of the (cooled) foam block. The foam samples were then wrapped in aluminum foil and sealed in polyethylene bags. Each sample had dimensions of 100 × 40 × 40 mm (approximately 9 g). For each foam block, three samples were taken for aldehyde determination.

[0112] Sealed samples were sent for direct determination immediately upon receipt. Before analysis, the sample was weighed to an accuracy of 0.001 g on an analytical balance. 50 mL of distilled water was pipetted into each of the used glass vials. The sample was introduced into the vials, the containers were sealed, and the vials were kept at 60 °C for 3 hours in a thermal cabinet. After the test period, the containers were removed from the thermal cabinet. After standing at room temperature for 60 minutes, the samples were removed from the test vials. Derivatization was then performed using the DNPH method (dinitrophenylhydrazine). For this, 900 μL of aqueous phase was mixed with 100 μL of DNPH solution. The DNPH solution was prepared as follows: 50 mg of DNPH in 40 mL of MeCN (acetonitrile) was acidified with 250 μL of dilute HCl (1:10) and brought to 50 mL with MeCN. After derivatization, the sample was analyzed by HPLC. Separation into individual aldehyde homologues was performed.

[0113] HPLC instrument parameters

[0114] The following instruments were used for analysis:

[0115] Agilent Technologies 1260

[0116] Column: Phenomenex Luna250*4.6mm C18, 5μm particle size

[0117] Eluent: Water-acetonitrile gradient

[0118] Detection: UV 365nm

[0119] Results of foaming experiment

[0120] The results of the effects of the recycled polyols according to the present invention on the foaming process and physical properties of the resulting thermosetting flexible PU foams are compiled in the table below. Thermosetting flexible PU foams were prepared according to formulation 1 in Table 2 using standard virgin polyols, recycled polyols not of the present invention, and recycled polyol 2 of the present invention.

[0121] Table 3: Foaming results and physical properties of foams using different types of polyols according to formulation 1 in Table 2.

[0122]

[0123] The foaming results in Table 3 show that using the recycled polyol 2 (foam #8) of this invention instead of the standard virgin polyol is effective. 1104 can be used to prepare soft PU foam with similar foaming and processing characteristics to the reference foam (#6). Furthermore, the physical properties of all foams are similar to the reference foam. Conversely, it is impossible to produce any reasonable foam using 100 pphp of the non-inventive recycled polyol 1; the foam is collapsing (foam #7).

[0124] The results of the effect of the recycled polyols according to the present invention on foam emissions at room temperature are compiled in Table 4. Thermosetting flexible PU foam was prepared according to formulation 2 in Table 2 by using standard virgin polyols, recycled polyol 1 (not of the present invention), and recycled polyol 2 of the present invention.

[0125] Table 4: Results of foam emission and odor tests using different polyol types based on formulation 2 in Table 2.

[0126]

[0127]

[0128] It was found that the thermosetting flexible PU foam according to the invention has low emissions when using emission-optimized additives. This can be seen in VOC testing according to DIN EN ISO 16000-9:2008-04. Although the total emissions increase slightly when using 100 pphp of the recycled polyol 2 of the invention (from 50 μg / m³ for foam #9). 3 Increased to 125 μg / m³ for foam #11 3 However, emissions are still far below 500 μg / m³. 3 The typical TVOC limit is [not specified]. Therefore, the recycled polyol 2 of the present invention is suitable for low-emission formulations. Conversely, it is impossible to generate any reasonable foam by using 100 pphp of the non-inventive recycled polyol 1.

[0129] The results in Table 4 show that using the recovered polyol 2 of this invention instead of the standard virgin polyol is effective. 1104 can be used to prepare soft PU foam with similar odor characteristics and aldehyde emissions. Formaldehyde, acetaldehyde, and propionaldehyde emissions, measured according to VDA275, are within similar ranges to foams #9 and #11.

Claims

1. A method for hydrolyzing polyurethane, the method comprising contacting the polyurethane with water in the presence of a strong inorganic base and a quaternary ammonium salt containing an ammonium cation as a catalyst to produce a polyether containing active hydrogen and an organic polyamine, wherein the strong inorganic base has a pK at 25°C. b If the value is less than 1, the ammonium cation contains 6 to 14 carbon atoms if the ammonium cation does not contain a benzyl residue, or contains 6 to 12 carbon atoms if the ammonium cation contains a benzyl residue.

2. The method according to claim 1, wherein the polyurethane is prepared by reacting a hydrogen-containing polyether with an organic polyisocyanate.

3. The method according to claim 1, wherein the polyether containing active hydrogen is a polyether polyol.

4. The method according to claim 1, wherein the strong inorganic base has a pKb value of 0.5 to -2 at 25°C.

5. The method according to claim 1, wherein the strong inorganic base has a pKb value of 0.25 to -1.5 at 25°C.

6. The method according to claim 1, wherein the strong inorganic base has a pKb value of 0 to -1 at 25°C.

7. The method according to claim 1, wherein the strong inorganic base is selected from alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides, and mixtures thereof.

8. The method according to claim 7, wherein the alkali metal is selected from Na, K and Li and mixtures thereof, and / or the alkaline earth metal is selected from Be, Mg, Ca, Sr, Ba and mixtures thereof.

9. The method according to claim 8, wherein the alkali metal is selected from Na and K and mixtures thereof.

10. The method according to claim 8, wherein the alkaline earth metal is selected from Mg and Ca and mixtures thereof.

11. The method according to any one of claims 1 to 10, wherein the catalyst is a quaternary ammonium salt having the general formula R1R2R3R4NX, wherein R1, R2, R3 and R4 are the same or different, and are hydrocarbon groups selected from alkyl, aryl and arylalkyl, and X is selected from halide ions, bisulfate, alkyl sulfate, carbonate, bicarbonate, carboxylate or hydroxide ions.

12. The method according to claim 11, wherein the halide ion is a chloride ion and / or a bromide ion.

13. The method according to claim 11, wherein the alkyl sulfate is selected from methyl sulfate and ethyl sulfate.

14. The method according to claim 11, wherein the carboxylate ion is an acetate ion.

15. The method of claim 11, wherein R1 to R3 may be the same or different, and are alkyl groups having 1 to 6 carbon atoms, wherein the alkyl group is straight-chain, branched, cyclic, saturated or unsaturated. -R4 is selected from alkyl groups having 3 to 11 carbon atoms, aryl groups having 6 to 11 carbon atoms, and aralkyl groups having 7 to 11 carbon atoms, wherein the alkyl group is straight-chain, branched, cyclic, saturated, or unsaturated, and -X is selected from halide ions, bisulfate ions, alkyl sulfate ions, carbonate ions, bicarbonate ions, acetate ions, or hydroxide ions.

16. The method of claim 15, wherein R1 to R3 are alkyl groups having 1 to 5 carbon atoms.

17. The method of claim 15, wherein R1 to R3 are alkyl groups having 1 to 4 carbon atoms.

18. The method of claim 15, wherein R1 to R3 are alkyl groups having 1 to 3 carbon atoms.

19. The method according to claim 15, wherein R1 to R3 are alkyl groups having one or two carbon atoms.

20. The method of claim 15, wherein R1 to R3 are alkyl groups having one carbon atom.

21. The method of claim 15, wherein R1 to R3 are straight-chain, saturated alkyl groups.

22. The method of claim 15, wherein R4 is selected from alkyl groups having 3 to 10 carbon atoms.

23. The method of claim 15, wherein R4 is selected from alkyl groups having 3 to 8 carbon atoms.

24. The method of claim 15, wherein R4 is selected from alkyl groups having 4 to 6 carbon atoms.

25. The method of claim 15, wherein R4 is selected from aryl groups having 6 to 10 carbon atoms.

26. The method of claim 15, wherein R4 is selected from aryl groups having 6 to 8 carbon atoms.

27. The method of claim 15, wherein R4 is selected from aralkyl groups having 7 to 10 carbon atoms.

28. The method of claim 15, wherein R4 is selected from aralkyl groups having 7 to 9 carbon atoms.

29. The method of claim 15, wherein when R4 is selected from alkyl groups, the alkyl group is a straight-chain, saturated alkyl group.

30. The method of claim 15, wherein the halide ion is a chloride ion and / or a bromide ion.

31. The method according to claim 15, wherein the alkyl sulfate is selected from methyl sulfate and ethyl sulfate.

32. The method of claim 11, wherein R4 is different from a benzyl residue, and R1 to R4 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 6 to 14.

33. The method of claim 32, wherein R1 to R4 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 7 to 14.

34. The method of claim 32, wherein R1 to R4 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 8 to 13.

35. The method of claim 11, wherein R4 is a benzyl residue, and R1 to R3 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 6 to 12.

36. The method of claim 35, wherein R1 to R3 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 7 to 12.

37. The method of claim 35, wherein R1 to R3 are selected such that the total number of carbon atoms in the quaternary ammonium cation is 8 to 11.

38. The method according to any one of claims 1 to 10, further comprising the additional step of separating and recovering organic polyamines and / or polyethers containing active hydrogen.

39. The method according to claim 38, wherein the polyether containing active hydrogen is a polyether polyol.

40. The method according to any one of claims 1 to 10, wherein the polyurethane is foamed.

41. The method according to any one of claims 1 to 10, wherein the polyurethane is reacted with water, the alkali, and the catalyst under the following conditions, At temperatures between 80℃ and 200℃, and / or The reaction time can range from 1 minute to 14 hours. and / or At atmospheric pressure.

42. The method according to claim 41, wherein the reaction temperature is from 90°C to 180°C.

43. The method according to claim 41, wherein the reaction temperature is from 95°C to 170°C.

44. The method according to claim 41, wherein the reaction temperature is from 100°C to 160°C.

45. The method of claim 41, wherein the reaction time is from 1 minute to 12 hours.

46. ​​The method of claim 41, wherein the reaction time is from 5 minutes to 12 hours.

47. The method of claim 41, wherein the reaction time is from 10 minutes to 11 hours.

48. The method of claim 41, wherein the reaction time is from 20 minutes to 10 hours.

49. The method of claim 41, wherein the reaction time is from 20 minutes to 8 hours.

50. The method of claim 41, wherein the reaction time is from 20 minutes to 7 hours.

51. The method according to any one of claims 1 to 10, wherein at least 0.5% by weight of catalyst is used based on the weight of the polyurethane.

52. The method of claim 51, wherein 0.5 to 15% by weight of catalyst is used based on the weight of the polyurethane.

53. The method of claim 51, wherein 1 to 10% by weight of catalyst is used based on the weight of the polyurethane.

54. The method of claim 51, wherein 1 to 8% by weight of catalyst is used based on the weight of the polyurethane.

55. The method of claim 51, wherein 1 to 7% by weight of catalyst is used based on the weight of the polyurethane.

56. The method of claim 51, wherein 2 to 6% by weight of catalyst is used based on the weight of the polyurethane.

57. The method according to any one of claims 1 to 10, wherein the weight ratio of alkali to polyurethane is 0.01 to 25.

58. The method of claim 57, wherein the weight ratio of alkali to polyurethane is 0.1 to 15.

59. The method of claim 57, wherein the weight ratio of alkali to polyurethane is 0.2 to 10.

60. The method of claim 57, wherein the weight ratio of alkali to polyurethane is 0.5 to 5.

61. The method according to any one of claims 1 to 10, wherein an alkaline solution comprising alkali and water is used.

62. The method of claim 61, wherein the concentration of the alkali is greater than or equal to 5% by weight, based on the weight of the alkali solution.

63. The method of claim 61, wherein the concentration of the alkali is 5 to 70% by weight, based on the weight of the alkali solution.

64. The method of claim 61, wherein the concentration of the alkali is 5 to 60% by weight, based on the weight of the alkali solution.

65. The method of claim 61, wherein the concentration of the alkali is 10 to 50% by weight, based on the weight of the alkali solution.

66. The method of claim 61, wherein the concentration of the alkali is 15 to 40% by weight, based on the weight of the alkali solution.

67. The method of claim 61, wherein the concentration of the alkali is 20 to 40% by weight, based on the weight of the alkali solution.

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