Depolymerization of polyurethanes under mild conditions

Abstract

The present invention relates to an improved process for the depolymerization of polyurethanes under mild conditions wherein polyether polyols and polyamines can be recovered in high yields.

Description

[0001] The present invention relates to an improved process for the depolymerization of polyurethanes under mild conditions wherein polyether polyols and polyamines can be recovered in high yields.

[0002] Polyurethane is a material with considerable utility in the production of rigid and flexible foams, solid and microcellular 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 in the past 50 years. At present, thousands of tons of polyurethane are produced every year in the whole world. Unfortunately, most polyurethanes are thermosetting materials that are crosslinked to a certain extent. Different from thermoplastics (such as polyethylene, polypropylene and polystyrene), waste material or waste polyurethane can therefore not be easily melted again or reprocessed into useful articles. Due to the great desire to reuse or reclaim a large amount of waste material or waste polyurethane produced each year for economic and environmental reasons, rather than burning it or discarding it in landfills, a large amount of creative efforts have been put into designing the method for reclaiming useful chemical components from waste polyurethane materials.

[0003] For example, EP 0 835 901 A2 discloses the use of glycolysis for the recycling of PU (polyurethane) waste (including both hard and soft types of products), i.e., depolymerization. These processes require multiple steps, such as (1) grinding, (2) gradual addition of the waste to diethylene glycol in the presence of a catalyst, (3) alkoxylation, and (4) degassing and filtration to recover the polyol.

[0004] Waste polyurethane foam can also be recycled via aminolysis and the aminolysis process is recovered using ammonia, amines or alkanolamines to recover monomeric polyols that can be reused for PU synthesis. For example, DE 102006036007 A1 describes a process in which polyurethanes and polyureas are recycled via aminolysis.

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

[0006] Hydrolysis methods have also been tested for the depolymerization of polyurethanes in prior art, such as US Pat. No. 4,196,148 A. However, the known use of base-catalyzed hydrolysis of polyurethanes to recover polyether polyols and polyamines has several disadvantages. At relatively low temperatures, the hydrolysis rate is slow, and correspondingly, the hydrolysis is incomplete. At higher temperatures, the rate is faster, but certain undesirable side reactions may occur. For example, US Pat. No. 5,208,379 proposes a method for hydrolyzing a polyurethane prepared by reacting an active hydrogen-containing polyether with an organic polyisocyanate. The method comprises 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 at a temperature effective to produce the active hydrogen-containing polyether and organic polyamine. The method of US Pat. No. 5,208,379 is disadvantageous due to the highly corrosive conditions employed. Implementation in a commercial plant requires specialized, very expensive equipment. Although US Pat. No. 5,208,379 discloses in its general description that the reaction temperature can be selected within 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 process of US Pat. No. 5,208,379 cannot be economically used at lower temperatures.

[0007] Therefore, there is still an urgent need to provide more efficient methods for polyurethane recycling so as to recover polyether polyols and / or polyamines with high quality and high yield.

[0008] The subject of the present invention is to provide a new process for the depolymerization of polyurethanes which overcomes the above-mentioned disadvantages of the prior art processes.

[0009] A particular subject matter of the present invention is to provide a process which can be operated in standard equipment, namely steel reactors.

[0010] Another specific problem of the present invention was to provide a process which can be operated at lower temperatures than in the prior art and which has good yields.

[0011] Another specific problem addressed by the present invention is to provide a process that makes it possible to obtain polyether polyols and / or polyamines of a quality very close to that of the raw materials used for preparing polyurethanes to be recycled. It should be possible to use the recycled polyether polyols and / or polyamines in a high proportion for preparing new polyurethanes.

[0012] Other problems addressed by the present invention but not described heretofore will follow from the ensuing description, examples and claims.

[0013] The present inventors have surprisingly found a method for hydrolyzing a polyurethane, preferably a polyurethane prepared by reacting an active hydrogen-containing polyether with an organic polyisocyanate, to obtain an active hydrogen-containing polyether, preferably a polyether polyol, and an organic polyamine in high yield, the method comprising contacting the polyurethane with water in the presence of a base and a catalyst, the base comprising an alkali metal cation and / or an ammonium cation and having a pK at 25°C of b The value is 1 to 10, and the catalyst is selected from quaternary ammonium salts containing 6 to 30 carbon atoms, and organic sulfonates containing at least 7 carbon atoms.

[0014] It is particularly surprising that, contrary to the teaching of US Pat. No. 5,208,379, a variety of inexpensive and / or less corrosive or non-corrosive bases can be used to effectively depolymerize polyurethanes.

[0015] The method of the present invention is very flexible with respect to the catalyst used. The inventors have found that ammonium cations with a low carbon number can be used just as effectively as ammonium cations with a higher carbon number. This provides greater flexibility in operating temperature.

[0016] The recovered active hydrogen-containing polyether and / or organic polyamine of the present invention has excellent quality and can be used in high proportions to prepare new polyurethane foam. Even when 100% of the active hydrogen-containing polyether of the present invention is used to prepare new polyurethane foam, high-quality polyurethane foam can be obtained. Without being bound by any theory, the inventors believe that, under specific mild reaction conditions, the method of the present invention avoids the formation of potentially problematic byproducts during polyurethane production.

[0017] An embodiment of the present invention is therefore a process as defined in claim 1, the dependent claims and the description. Another embodiment is the use of the recovered active hydrogen-containing polyethers, preferably polyether polyols, and / or organic polyamines according to the invention for the preparation of polyurethanes, in particular polyurethane foams.

[0018] Before describing the present invention in more detail, some important terms are defined as follows:

[0019] As used in the specification, examples, and claims, the verb "to comprise" and its conjugations are used in its non-limiting sense to mean that the items following the word are included, but items not specifically mentioned are not excluded. "Comprising" includes "consisting," which means that as a preferred embodiment, the items following the word "comprising" are included, but any additional, not specifically mentioned items are not included.

[0020] Reference to an element with the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the element. Thus, the indefinite article "a" or "an" usually means "one or more".

[0021] The terms "catalyst" and "activator" are used synonymously in the present invention.

[0022] In the context of the present invention, polyurethane (PU) is particularly understood to mean a product obtainable by the reaction of a polyisocyanate and a polyol or a compound having isocyanate-reactive groups. Polyurethanes that can be subjected to the method of the present invention are preferably those prepared from polyethers and polyisocyanates containing active hydrogen. Polyurethanes of this type are 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 method of the present invention.

[0023] The active hydrogen-containing polyether is preferably a polyether polyol (i.e., a polyether having primary and / or secondary end groups, preferably hydroxyl groups), but may also be an amine-functionalized polyether (e.g., "Jeffamine" polyoxypropylamine sold by Texaco Chemical Co.). Such materials are typically prepared by catalytic ring-opening polymerization of one or more cyclic ethers such as epoxides, oxetanes, or oxolanes. Initiators having two or more active hydrogens, such as polyols, amines, or acids, may be used to vary the functionality (number of active hydrogens) of the polyether. If more than one type of cyclic ether is used, they may be reacted simultaneously (to obtain a random copolymer) or sequentially (to obtain a block copolymer). Exemplary cyclic ethers include propylene oxide, ethylene oxide, butylene oxide, tetrahydrofuran, and oxetanes. Examples of suitable active 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.

[0024] The structure of the active hydrogen-containing polyether, preferably polyether polyol, recovered in the process of the present invention is related to the structure of the active hydrogen-containing polyether used for preparing the polyurethane to be treated in the process of the present invention.

[0025] The structure of the polyamine recovered in the process of the present invention is related to the structure of the polyisocyanate used to prepare the polyurethane to be treated in the process of the present invention. The "polyamine" used in the present invention includes diamines and preferably includes amines having two or more primary amino groups in the molecule.

[0026] The polyurethane used in the method for the present invention can be derived from any polyisocyanate reactant (that is, an organic compound containing two or more isocyanate groups). Suitable polyisocyanates include but are not limited to aliphatic diisocyanates, alicyclic diisocyanates, aryl alkyl diisocyanates, aromatic diisocyanates (for example toluene diisocyanate and diisocyanato diphenylmethane), aromatic triisocyanates and isocyanate mixtures, such as the isocyanate commonly referred to as " PMDI ". Certainly, also can use modified, masked or blocked polyisocyanates.

[0027] The polyurethane used in the method of the present 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 diols and diamines or polyamines), physical or chemical blowing agents, flame retardants, surfactants, fillers, stabilizers, antioxidants, colorants, polymers other than polyurethane polymers (e.g., styrene-acrylonitrile copolymers, such as those found in polymer polyols), catalysts, such as catalysts that promote the gelling reaction (isocyanate-polyol), the blowing reaction (isocyanate-water), and / or the dimerization or trimerization of the isocyanate. The polyurethane may be in solid, microcellular, or foamed form and may be a rubber, elastomer, soft material to a hard rigid substance.

[0028] In order to facilitate handling of the polyurethane, it is preferably desirable to chop, crush, grind or divide the polyurethane so that it is in the form of relatively small particles or granules. If the polyurethane is a foam, it can be partially or completely compressed before contacting with water, a strong base and an activator. If the polyurethane is in solid form, an initial crushing step is very advantageous in order to maximize the surface area available for reaction (thereby reducing the reaction time required to achieve the desired level of hydrolysis).

[0029] The process of the present invention will result in the efficient hydrolytic cleavage of the urethane and urea bonds present in the treated polyurethanes to produce active hydrogen-containing polyethers, particularly polyether polyols, polyamines, and, if the polyurethanes are prepared using chain extenders or curing agents, low molecular weight glycols, diols, diamines.

[0030] The base used in the present invention comprises an alkali metal cation and / or an ammonium cation, and has a pK at 25°C. bThe value is 1 to 10, preferably 1 to 8, more preferably 1 to 7, and most preferably 1.5 to 6. Organic bases (i.e. bases containing one or more C-H bonds) or inorganic bases (i.e. bases not containing C-H bonds) can be used. Preferably, a base with low or no corrosiveness is used. Particularly preferably, a base selected from the group consisting of alkali metal phosphates, alkali metal hydrogenphosphates, alkali metal carbonates, alkali metal silicates, alkali metal hydrogencarbonates, alkali metal acetates, alkali metal sulfites, ammonium hydroxide, and mixtures thereof is used in the process of the present invention. The ammonium cation in the base of the present invention includes NH4 + 、NHR3 + NH2R2 + NH3R + For example, ammonium hydroxide includes NH4OH, NHR3OH, NH2R2OH, NH3ROH, wherein R represents an organic residue, and wherein the residue R in the ammonium cation may be the same or different. Preferably, the ammonium cation of the base represents NH4 + It is particularly preferred that the base according to the invention does not contain alkaline earth metal cations.

[0031] Even more preferably, a base selected from the group consisting of alkali metal phosphates, alkali metal carbonates, alkali metal silicates, ammonium hydroxide and mixtures thereof is used.

[0032] Most preferably, a base selected from the group consisting of alkali metal carbonates, alkali metal silicates and mixtures thereof is used.

[0033] Preferred alkali metals are selected from the group consisting of Na, K and Li and mixtures thereof, and most preferably selected from the group consisting of Na and K and mixtures thereof.

[0034] The use of the above-mentioned bases allows the process of the invention to be run in standard equipment, preferably in steel reactors, without the need for special corrosion protection, thus significantly contributing to a reduction in the investment costs of the plant. Very cheap bases can also be used, which contributes to a reduction in operating costs.

[0035] The amount of base in the reaction mixture must be sufficient to catalyze the desired hydrolysis of the polyurethane at a viable rate. Preferably, the weight ratio of base to polyurethane is in the range of 0.01 to 50, more preferably 0.1 to 25, and most preferably 0.5 to 20. Preferably, the base is used in the form of a base solution comprising base and water, even more preferably as a saturated base solution. If a saturated base solution is used, it is preferred that the weight ratio of saturated base solution to polyurethane, calculated at 25° C., is preferably in the range of 0.5 to 25, more preferably 0.5 to 15, even more preferably 1 to 10, and most preferably 2 to 7.

[0036] Quaternary ammonium salts, organic sulfonates or some combination or mixture thereof are used as phase transfer catalysts in the method of the present invention. Preferably, quaternary ammonium salts are used.

[0037] Although the addition of even trace amounts of these catalysts will accelerate the rate of hydrolysis, it is preferred to use at least 0.5 wt %, more preferably 0.5 to 15 wt %, even more preferably 1 to 10 wt %, particularly preferably 1 to 8 wt %, especially preferably 1 to 7 wt %, and most preferably 2 to 6 wt % catalyst, based on the weight of the polyurethane.

[0038] Quaternary ammonium salts useful in the present invention include those organic nitrogen-containing compounds in which the molecular structure includes a central positively charged nitrogen atom, i.e., an ammonium cation, attached to four organic (i.e., hydrocarbyl) groups, and a negatively charged anion, such as a halide, preferably chloride, bromide, bisulfate, alkyl sulfate, preferably methylsulfate and ethylsulfate, carbonate, bicarbonate, carboxylate, preferably acetate, or hydroxide.

[0039] Quaternary ammonium salts are well known and are 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.

[0040] It has been found that quaternary ammonium salts containing ammonium cations having a total of 6 to 30 carbon atoms are most effective in the process of the present invention. Contrary to the teaching of US Pat. No. 5,208,379, the inventors have found that if ammonium cations containing a total of more than 30 carbon atoms are used, the yield is significantly reduced. This is also true if the number of carbon atoms is less than 6.

[0041] Catalysts that have proven to be highly effective and are therefore preferably used in the process of the present invention are quaternary ammonium salts having the general structure R1R2R3R4NX, wherein R1, R2, R3 and R4 are identical or different and are hydrocarbon radicals selected from alkyl, aryl and arylalkyl groups, and X is selected from halides, preferably chloride and / or bromide, bisulfate, alkyl sulfate, preferably methylsulfate and ethylsulfate, carbonate, bicarbonate, carboxylate, preferably acetate, or hydroxide.

[0042] Preferably

[0043] - R1 and R2 are identical or different and are an alkyl group having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5 and most preferably 1 to 4 carbon atoms, wherein the alkyl group may be linear, branched, cyclic, saturated or unsaturated, most preferably a linear saturated alkyl group,

[0044] - R3 is selected from an alkyl group having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, especially preferably 1 to 5, most preferably 1 to 4 carbon atoms, an aryl group having 6 to 14, preferably 6 to 12, most preferably 6 to 10 carbon atoms, and an aralkyl group having 7 to 14, preferably 7 to 12, most preferably 7 to 10 carbon atoms, wherein the alkyl group may be linear, branched, cyclic, saturated or unsaturated, most preferably linear and saturated,

[0045] -R4 is selected from an alkyl group having 3 to 12, preferably 3 to 10, more preferably 3 to 7, most preferably 4 to 6 carbon atoms, an aryl group having 6 to 14, preferably 6 to 12, most preferably 6 to 10 carbon atoms, and an aralkyl group having 7 to 14, preferably 7 to 12, most preferably 7 to 10 carbon atoms, wherein the alkyl group may be linear, branched, cyclic, saturated or unsaturated, most preferably linear and saturated,

[0046] and

[0047] -X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, carboxylate, preferably acetate, or hydroxide.

[0048] In a first preferred embodiment, the catalyst is a quaternary ammonium salt having the general structure R1R2R3R4NX, wherein R1 to R4 are as defined above and are selected so that the sum of the carbon atoms of the ammonium cation is 6 to 14, preferably 7 to 14, more preferably 8 to 13.

[0049] In a second preferred embodiment, the catalyst is a quaternary ammonium salt having the general structure R1R2R3R4NX, wherein R1 to R4 are as previously defined and are selected so that the sum of the carbon atoms of the ammonium cation is 15 to 30, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20.

[0050] In a third preferred embodiment, the catalyst is a quaternary ammonium salt having the general structure R1R2R3R4NX, wherein R1 to R4 and X are as defined above and are selected so that the total number of carbon atoms in the ammonium salt is 6 to 14, preferably 7 to 14, more preferably 8 to 13.

[0051] In a fourth preferred embodiment, the catalyst is a quaternary ammonium salt having the general structure R1R2R3R4NX, wherein R1 to R4 and X are as previously defined and are selected so that the sum of the carbon atoms of the ammonium salt is from 15 to 30, preferably from 15 to 28, more preferably from 15 to 24, even more preferably from 16 to 22, and most preferably from 16 to 20.

[0052] The most preferred quaternary ammonium salts suitable for use as activators in the process of the present invention include tetrabutylammonium hydrogen sulfate, benzyltrimethylammonium chloride, tributylmethylammonium chloride, and trioctylmethylammoniummethylsulfate.

[0053] Another class of activators useful in the practice of the present invention includes organic sulfonates (i.e., organic compounds containing at least one sulfonic acid functional group). These materials have the general formula

[0054] R-SO3M

[0055] wherein R is a linear, branched, cyclic, saturated or unsaturated alkyl, aryl or alkylaryl group containing at least 7 carbon atoms, and M is an alkali metal (e.g., sodium, potassium), an alkaline earth metal (e.g., calcium, barium, magnesium) or ammonium (NH4, NHR3, NH2R2, NH3R), wherein M may also be hydrogen, provided that a sufficiently strong base is present during the hydrolysis reaction to convert the organic sulfonate into its salt (anion) form and R is an organic moiety such as methyl or ethyl. Organic sulfonates are described in Cahn et al., "Surfactants and Detersive Systems", Encyclopedia of Chemical Technology, Vol. 22, pp. 347-360 (1983) and McCutcheon, Synthetic Detergents, (1950) pp. 120-151. Preferably, an organic sulfonate selected from alkylaryl sulfonates, α-olefin sulfonates, petroleum sulfonates and naphthalene sulfonates is used.

[0056] Since the process of the present invention is preferably operated at the lowest possible temperature, a quaternary ammonium salt is preferably used as an activator. Preferably, in the process of the present invention, the polyurethane is reacted with water, a base, and a 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 is insufficient. From an economic point of view, excessively high temperatures are inefficient and may cause side reactions, forming undesirable by-products.

[0057] Preferably, the polyurethane is reacted with water, a base and a catalyst for 1 minute to 14 hours, preferably 1 minute to 12 hours, more preferably 5 minutes to 12 hours, even more preferably 10 minutes to 12 hours, particularly preferably 20 minutes to 12 hours, especially preferably 20 minutes to 11 hours, most preferably 30 minutes to 10 hours.

[0058] While water acts as a reactant in the desired polyurethane hydrolysis reaction and therefore need not be present in stoichiometric excess relative to the carbamate functional groups in the polymer to be hydrolyzed, it is generally desirable to utilize a large amount of water so that it can conveniently serve as a reaction medium and solvent or carrier for the strong base and activator. For these reasons, the water is preferably present in condensed (liquid) form. Typically, the weight ratio of polyurethane to water is 3:1 to 1:15.

[0059] The hydrolysis is preferably carried out at atmospheric pressure, although superatmospheric pressure may be employed if desired. Optionally, a water-miscible or water-immiscible solvent such as an alcohol, ketone, ester, ether, amide, sulfoxide, halogenated hydrocarbon, aliphatic hydrocarbon, or aromatic hydrocarbon may be present in the reaction mixture to facilitate the hydrolysis process or to aid in the recovery of the reaction product.

[0060] The hydrolysis reaction can be carried out in a batch, continuous or semi-continuous manner in any suitable vessel or other equipment (e.g., a stirred tank reactor or a screw extruder) whereby the polyurethane is contacted with water in the presence of a base and an activator. It is generally preferred to agitate or stir the reaction components to ensure intimate contact, a rapid hydrolysis rate and proper temperature control.

[0061] The active hydrogen-containing polyether, organic polyamine, chain extender and curing agent produced in the 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 (for example, using a water-immiscible organic solvent as an extractant), distillation, precipitation, and filtration.

[0062] The recovered active hydrogen-containing polyethers, particularly polyether polyols, obtained in the process of the present invention are of excellent quality. The inventors have discovered that they can be used to prepare high-quality polyurethane foams even without the addition of virgin polyether polyol. This represents a significant improvement over prior art polyurethane depolymerization processes.

[0063] The recovered polyamines can be converted into organic polyisocyanates by conventional methods and similarly used as components of polyurethanes.

[0064] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. Therefore, the following examples should be construed as merely illustrative and not limiting of the claims or the remainder of the disclosure.

[0065] Examples 1-10 and Comparative Examples 1 to 7

[0066] A 25 g compressed polyurethane foam block (approximately 1 cm x 1 cm) was placed in a Parr Instrument Company reactor equipped with a PTFE liner and a mechanical stirrer, and 75 g of an aqueous base solution was added. The catalyst was then added, the reactor closed, and heated to operating temperature. After the desired reaction time, the mixture was cooled, the reactor opened, and the reaction mixture transferred to a round-bottom flask.

[0067] The water was removed and the remaining solid was extracted with cyclohexane. The cyclohexane solution was washed with 1N aqueous HCl, dried over magnesium sulfate and the solvent was removed. After drying and removing the solvent, the solid was extracted with warm toluene to obtain the amine.

[0068] In Table 1 are given the alkaline solution and catalyst used, their amounts, reaction time and temperature, and the yields of recovered polyether polyol and amine.

[0069] Table 1

[0070]

[0071] TBMAC = tributylmethylammonium chloride (C = 13)

[0072] TBAHS = Tetrabutylammonium hydrogen sulfate (C = 16)

[0073] ND = Not Determined

[0074] The examples show that the process of the invention achieves good yields even at reaction temperatures below 140° C. and under non-corrosive conditions. If the pKb value of the base is too high, as shown in Comparative Example CE 1, or if an alkaline earth metal base is used, as shown in Comparative Examples CE 2 to CE 7, the yield decreases significantly.

[0075] Performance testing of recycled polyols

[0076] Preparation of thermosetting flexible PU foam (flexible block foam)

[0077] For the performance testing of recycled polyols, the heat-cured flexible PU foam formulations specified in Table 2 were used.

[0078] Table 2: Formulations for the preparation of heat-cured flexible PU foams.

[0079]

[0080] 1) Polyol 1: Standard virgin polyol available from Covestro 1104, which 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 recovery polyol of the present invention or a non-recovery polyol of the present invention. The recovery polyol is obtained by chemically recycling flexible polyurethane foam. The recovery polyol of the prior art is obtained by the steps described in the following paragraphs. As the recovery polyol of the present invention, the polyol of Example 6 is used.

[0081] 2) T9, available from Evonik Industries: tin(II) salt of 2-ethylhexanoic acid.

[0082] 3) DMEA: dimethylethanolamine, available from Evonik Industries. An amine catalyst used in the preparation of polyurethane foams.

[0083] 4) Polyether-modified polysiloxanes, available from Evonik Industries.

[0084] 5) Toluene diisocyanate T 80 from Covestro (80% of 2,4-isomer, 20% of 2,6-isomer), 3 mPa·s, 48% NCO, functionality 2.

[0085] 6) EF, non-emission metal catalyst, available from Evonik Industries: tin(II) salt of ricinoleic acid.

[0086] 7) NE1050: Low-emission amine catalyst, available from Evonik Industries.

[0087] 8) Low-emission polyether-modified polysiloxanes with <0.03 wt% total cyclic siloxanes, available from Evonik Industries.

[0088] Preparation of recycled polyols for performance testing

[0089] Recycling polyol 1 (not of the present invention)

[0090] 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

[0091] 300.2 g of compressed polyurethane foam blocks (approximately 1 cm x 1 cm) were charged into a reactor from Parr Instruments equipped with a glass liner and a mechanical stirrer. According to Formulation 1 of Table 2, conventional polyols 1104 prepares the polyurethane foam used.

[0092] 152.64g polyol 1104, 75.63 g of phthalic acid and 11.97 g of hydrogen peroxide (30% by weight in water) were added to the foam block. The reaction mixture was heated to an internal temperature of 250° C. The reaction was maintained under these conditions at an internal temperature between 237° C. and 256° C. for 5 hours. After heating was stopped, a second portion of 140.63 g of 1104. The reaction mixture was decanted at 80°C and then cooled to room temperature. The cooled and decanted reaction mixture was used as non-inventive recycled polyol 1. This process was repeated to produce sufficient amounts of recycled polyol for foaming experiments.

[0093] Recovery of polyol 2 (present invention)

[0094] The recycled polyol of the present invention of Example 6 was used.

[0095] General procedure for preparing foam samples

[0096] For each foaming test, 300 g or 400 g of polyol was used; the other formulation ingredients were recalculated accordingly. For example, 1.00 part of a component would be expressed as 1.00 g of that substance per 100 g of polyol.

[0097] Foaming is carried out in a so-called hand mixing process. Formulation 1 or Formulation 2 specified in Table 2 is used. To this end, paper cups are charged with the various polyols, the corresponding amine catalyst, the tin catalyst 2-ethylhexanoate (II), water, and a foam stabilizer, and the contents are mixed for 60 seconds at 1000 rpm using a disk stirrer. After the initial stirring, the isocyanate (TDI) is added to the reaction mixture and stirred at 2500 rpm for 7 seconds. The reaction mixture is then immediately transferred to a paper-lined box (30 cm x 30 cm bottom area and 30 cm height). After pouring, the foam rises in the foam box. Ideally, the foam blew off when it reached its maximum rise and then fell back slightly. This opened up the cell membranes of the foam bubbles, resulting in the open-cell structure of the foam. Defined foam bodies were cut from the resulting heat-cured flexible PU foam blocks and further analyzed.

[0098] Characterization of soft PU foam:

[0099] The prepared flexible polyurethane foams were evaluated according to the following foam properties a) to l):

[0100] a) Foam fall (=settling) after the rise phase: Settling or further rise is determined by the difference in foam height immediately after bursting and 3 minutes after the bursting. The foam height is measured at its maximum point in the middle of the foam top using a needle attached to a centimeter scale. Positive values ​​describe foam settling after the burst; negative values, correspondingly, describe further rise after the burst.

[0101] b) Foam height: The height of the free-rising foam formed after 3 minutes. The foam height is reported in centimeters (cm).

[0102] c) Rise time: The time period between the completion of mixing of the reaction components and the collapse of the polyurethane foam. Rise time is reported in seconds (s).

[0103] d) Porosity Measurement by Dynamic Pressure: The air permeability of foams is determined by dynamic pressure measurement of the foams according to DIN EN ISO 4638:1993-07. The measured dynamic pressure is reported in mm of water column, with lower dynamic pressure values ​​indicating more open foam. The measured values ​​range from 0 to 300 mm of water column. The dynamic pressure is measured using an apparatus consisting of a nitrogen source, a pressure reducing valve with a pressure gauge, a flow adjustment screw, a wash bottle, a flow meter, a T-piece, an applicator nozzle, and a graduated glass tube filled with water. The applicator nozzle has an edge length of 100 x 100 mm, a weight of 800 g, an inner diameter of the outlet opening of 5 mm, an inner diameter of the lower applicator ring of 20 mm, and an outer diameter of the lower applicator ring of 30 mm. The measurement is performed by setting the nitrogen inlet pressure to 1 bar and the flow rate to 480 l / h via the pressure reducing valve. The amount of water in the graduated glass tube is set so that no pressure difference is generated and no reading is possible. For measurements on specimens measuring 250 x 250 x 50 mm, the applicator nozzle is placed on a corner of the specimen, flush with the edge, and in the (estimated) middle of the specimen (in each case on the side with the largest surface area). When a constant dynamic pressure has been established, the result is read. The final result is calculated by forming the average of the five measurements obtained.

[0104] e) Number of cells per cm (cell count): This is determined visually on the cut surface (measured in accordance with DIN EN 15702).

[0105] f) Compression hardness CLD, 40%, according to DIN EN ISO 33861:1997+A1:2010. The measured values ​​are reported in kilopascals (kPa).

[0106] g) Constant deflection compression set (also called compression set)

[0107] Five specimens each measuring 5 cm × 5 cm × 2.5 cm are cut out of the finished foam. The starting thickness is measured. According to DIN EN ISO1856 2018, the compression set is measured no earlier than 72 hours after preparation. The specimen is placed between the plates of the deformation device and compressed to 90% of its thickness (ie to 2.5 mm). Within 15 minutes, the specimen is placed in an oven at 70°C and left there for 22 hours. After this, the apparatus is removed from the oven, the specimens are removed from the apparatus within 1 minute, and they are placed on a wood surface. After 30 minutes of relaxation, the thickness is measured again and the compression set is calculated, and the results are reported as a percentage of the original thickness: DVR = (d0-dr) / d0×100%.

[0108] h) Tensile strength and elongation at break according to DIN EN ISO 1798: 2008. The measured values ​​for tensile strength are reported in kilopascals (kPa) and the measured values ​​for elongation at break are reported in percentage (%).

[0109] i) Rebound resilience according to DIN EN ISO 8307: 2007. The measured values ​​are reported in percent (%).

[0110] j) Emission characteristics at room temperature according to DIN EN ISO 16000-9:2008-04. Here, the type and amount of organic matter emitted by these materials are characterized. This analytical method is used to determine emissions from materials used in furniture and mattresses. This is achieved by measuring emissions at room temperature using a test chamber.

[0111] analyze

[0112] Specimens: sample preparation, sampling and specimen dimensions

[0113] The reaction mixture was transferred to a box (30 cm x 30 cm bottom area and 30 cm high) covered with a PE plastic bag with an open top. After pouring, the foam rose in the foam box. Ideally, the foam would burst when it reached its maximum height and then fall back slightly. This opened the cell membranes of the foam bubbles, resulting in an open-cell structure. After the foam rose and burst, the PE bag was closed 3 minutes after the burst. The foam was stored in this manner at room temperature for 12 hours to allow for complete reaction while preventing premature VOC escape. Subsequently, the PE bag was opened, and a 7 cm x 7 cm x 7 cm cube was removed from the center of the foam block, immediately wrapped in aluminum foil, and airtightly sealed in a PE bag. It was then transported to the analytical laboratory and the foam cube was introduced into a clean 30-liter glass test chamber. The conditions in the test chamber were controlled climate conditions (temperature 21°C, air humidity 50%). Half of the test chamber volume was replaced every hour. After 24 hours, a sample was removed from the test chamber air. Tenax adsorption tubes were used to absorb the VOCs. The Tenax tube is then heated and the released volatile substances are cryofocused in a cold trap of a temperature programmable evaporator with the aid of an inert gas flow. After the heating phase and cryofocusing, the cold trap is quickly heated to 280°C and the condensed substances are volatilized. They are then separated in a gas chromatography column and detected by mass spectrometry. Calibration with reference substances allows for a semi-quantitative assessment of emissions in terms of "μg / m 3" indicates. The quantitative reference substance for VOC analysis (VOC value) is toluene. Signal peaks can be assigned to substances using their mass spectra and retention indices. The following equipment was used for the 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), chromatographic column: HP Ultra2 (50m, 0.32mm, 0.52μm), carrier gas: helium. More detailed procedures can be found in DIN EN ISO 16000-9:2008-04.

[0114] k) Odor testing of the resulting foam. The finished foam was packaged in odor-neutral plastic bags and stored under airtight conditions. To evaluate the foam's odor, cubes measuring 10 cm x 10 cm x 10 cm were cut and transferred to 1 L jars. The sample was sniffed from the jars. The jars were sealed with screw caps. The jars were stored at 22°C for 24 hours before the odor test was performed. The odor test was evaluated by a panel of 13 trained odor testers. They were asked to rate the intensity of the odor, with low odor levels rated as +, medium odor as ++, and high odor as +++.

[0115] l) Aldehyde emissions according to VDA 275

[0116] In this method, a sample of defined mass and dimensions is placed above distilled water in a sealed 1-liter glass bottle and stored at a constant temperature for a defined period of time. The bottle is then cooled, and the absorbed aldehyde is measured in distilled water. The amount of aldehyde measured is based on the dry weight of the foam sample (mg / kg).

[0117] 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 the foam block at appropriate, representative locations evenly distributed across the width of the (cooled) foam block. The foam samples were then wrapped in aluminum foil and sealed in polyethylene bags. Each sample measured 100 x 40 x 40 mm thick (approximately 9 g). Three specimens were taken from each foam block for aldehyde determination.

[0118] The sealed samples were sent for direct measurement immediately upon receipt. Before analysis, the samples were weighed on an analytical balance to an accuracy of 0.001g. 50ml of distilled water was pipetted into each glass bottle used. The samples were introduced into the glass bottles, and the containers were sealed and kept at a constant temperature of 60°C in a thermal cabinet for 3 hours. After the test period, the containers were removed from the thermostat. After standing at room temperature for 60 minutes, the samples were removed from the test bottles. Derivatization was then carried out using the DNPH method (dinitrophenylhydrazine). To this end, 900μl of aqueous phase was mixed with 100μl of DNPH solution. The DNPH solution was prepared as follows: 50mg of DNPH in 40ml of MeCN (acetonitrile) was acidified with 250μl of dilute HCl (1:10) and supplemented to 50ml with MeCN. After derivatization was completed, the samples were analyzed by HPLC. Separation into individual aldehyde homologues was carried out.

[0119] HPLC instrument parameters

[0120] The following instruments were used for analysis:

[0121] Agilent Technologies 1260

[0122] Column: Phenomenex Luna250*4.6mm C18, 5μ particle size

[0123] Eluent: Water-acetonitrile gradient

[0124] Detection: UV 365nm

[0125] Results of the foaming experiment

[0126] The results of the effects of the recycled polyol according to the present invention on the foaming process and foam physical properties of the resulting heat-cured flexible PU foam are compiled in the table below. Heat-cured flexible PU foams were prepared according to Formulation 1 of Table 2 using standard virgin polyol, recycled polyol not according to the present invention, and recycled polyol according to the present invention.

[0127] Table 3: Foaming results and foam physical properties of foams using different types of polyols according to Formulation 1 of Table 2. For each foaming test, 400 g of polyol was used; the other formulation ingredients were recalculated accordingly.

[0128]

[0129]

[0130] The foaming results in Table 3 show that the recycled polyol 2 of the present invention can be used to replace the standard virgin polyol 1104, a soft PU foam can be prepared with similar foaming processing characteristics to the reference foam #1. In addition, the foam physical properties of porosity, cell count, ball rebound and compression set of the inventive foam #3 are similar to those of the reference foam #1. Compared to the reference foam #1, the physical properties in terms of elongation and tensile strength are even improved by using the inventive recycled polyol #2. In contrast, it is not possible to produce any reasonable foam by using 100 pphp of the non-inventive recycled polyol 1, which is collapsing (Foam #2). Only at a reduced usage level of 30 pphp of the non-inventive recycled polyol 1 and the standard virgin polyol A reasonable foam was obtained with a combination of 1104 and 1100 pphp (Foam #5). However, even at this lower usage level, the physical properties of the foam were inferior to those of the foam based on 100 pphp of the inventive recycled polyol 2 (Foam #3). Foam #5 was significantly more closed than either Foam #1 or Foam #3. Furthermore, Foam #5 exhibited inferior results for compression set (90% at 70°C), elongation, tensile strength, and ball rebound compared to Foam #3.

[0131] The results of the effect of recycled polyols according to the invention on the foam emissions at room temperature are compiled in Table 4. According to Formulation 2 of Table 2, heat-cured flexible PU foams were prepared by using standard virgin polyol, recycled polyol 1 (not according to the invention) or recycled polyol 2 according to the invention.

[0132] Table 4: Emission and odor test results for foams using different polyol types according to Formulation 2 of Table 2. For each foaming test, 300 g of polyol was used; the other formulation ingredients were recalculated accordingly.

[0133]

[0134]

[0135] It was found that the heat-cured flexible PU foam according to the present invention has low emissions if emission-optimized additives are used. This can be seen in the VOC test according to DIN EN ISO 16000-9:2008-04. Although the total emissions increased slightly when 100 pphp of recycled polyol 2 according to the present invention was used (from 50 μg / m3 for foam #9), the total emissions increased slightly when 100 pphp of recycled polyol 2 according to the present invention was used (from 50 μg / m3 for foam #9). 3 Increased to 140 μg / m in Foam #11 3 ), but the emission level is still well below 500μg / m 3 = Typical limits for TVOC. Therefore, recycled polyol 2 is suitable for low emission formulations. In contrast, it is not possible to generate any reasonable foam by using 100 pphp of recycled polyol 1 not according to the invention.

[0136] The results in Table 4 show that the recycled polyol 2 of the present invention can be used to replace the standard virgin polyol 1104, a flexible PU foam with similar odor characteristics and aldehyde emissions can be prepared. The emissions of formaldehyde, acetaldehyde and propionaldehyde measured according to VDA 275 are in a similar range to foam #9 and foam #11.

Claims

1. A method for hydrolyzing a polyurethane, comprising contacting the polyurethane with water in the presence of a base and a catalyst to produce a polyether containing active hydrogen, and an organic polyamine, wherein the base comprises an alkali metal cation and / or an ammonium cation and has a pK at 25° C. b The catalyst is selected from quaternary ammonium salts containing ammonium cations having 6 to 30 carbon atoms, and organic sulfonates containing at least 7 carbon atoms, wherein the base is selected from alkali metal phosphates, alkali metal hydrogenphosphates, alkali metal carbonates, alkali metal silicates, alkali metal hydrogencarbonates, alkali metal acetates, alkali metal sulfites, ammonium hydroxide and mixtures thereof.

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

4. The method of claim 1, wherein the base has a pK at 25°C. b The value is 1 to 8.

5. The method of claim 1, wherein the base has a pK at 25°C. b The value is 1 to 7. The method according to claim 1 , wherein the base has a pKb value of 1.5 to 6 at 25° C.

7. The method according to claim 1, wherein the alkali metal is selected from the group consisting of Na, K, Li, and mixtures thereof.

8. The method according to claim 7, wherein the alkali metal is selected from the group consisting of Na and K and mixtures thereof.

9. The method of any one of claims 1 to 8, wherein the catalyst is a quaternary ammonium salt having the general structure R1R2R3R4NX, wherein R1, R2, R3 and R4 are the same or different and are hydrocarbyl groups selected from alkyl, aryl and arylalkyl, and X is selected from halide, bisulfate, alkyl sulfate, carbonate, bicarbonate, carboxylate, or hydroxide.

10. The method according to claim 9, wherein the halide ion is chloride ion and / or bromide ion.

11. The method of claim 9, wherein the alkyl sulfate is methyl sulfate or ethyl sulfate.

12. The method of claim 9, wherein the carboxylate is acetate.

13. The method according to claim 9, wherein - R1 and R2 are the same or different and are an alkyl group having 1 to 12 carbon atoms, wherein the alkyl group is linear, branched, cyclic, saturated or unsaturated, -R3 is selected from an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, and an aralkyl group having 7 to 14 carbon atoms, wherein the alkyl group is linear, branched, cyclic, saturated or unsaturated, and -R4 is selected from an alkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, and an aralkyl group having 7 to 14 carbon atoms, wherein the alkyl group is linear, branched, cyclic, saturated or unsaturated, and -X is selected from halide, bisulfate, alkylsulfate, carbonate, bicarbonate, acetate, or hydroxide.

14. The method according to claim 13, wherein R1 and R2 are alkyl groups having 1 to 10 carbon atoms.

15. The method according to claim 13, wherein R1 and R2 are alkyl groups having 1 to 7 carbon atoms.

16. The method according to claim 13, wherein R1 and R2 are alkyl groups having 1 to 6 carbon atoms.

17. The method according to claim 13, wherein R1 and R2 are alkyl groups having 1 to 5 carbon atoms.

18. The method according to claim 13, wherein R1 and R2 are alkyl groups having 1 to 4 carbon atoms.

19. The method according to claim 13, wherein the alkyl groups of R1 and R2 are linear saturated alkyl groups.

20. The method according to claim 13, wherein R3 is selected from an alkyl group having 1 to 10 carbon atoms.

21. The method according to claim 13, wherein R3 is selected from an alkyl group having 1 to 7 carbon atoms.

22. The method according to claim 13, wherein R3 is selected from an alkyl group having 1 to 6 carbon atoms.

23. The method according to claim 13, wherein R3 is selected from an alkyl group having 1 to 5 carbon atoms.

24. The method according to claim 13, wherein R3 is selected from an alkyl group having 1 to 4 carbon atoms.

25. The method of claim 13, wherein R3 is selected from an aryl group having 6 to 12 carbon atoms.

26. The method of claim 13, wherein R3 is selected from an aryl group having 6 to 10 carbon atoms.

27. The method according to claim 13, wherein R3 is selected from aralkyl groups having 7 to 12 carbon atoms.

28. The method according to claim 13, wherein R3 is selected from aralkyl groups having 7 to 10 carbon atoms.

29. The method according to claim 13, wherein when R3 is selected from an alkyl group, the alkyl group is a straight chain.

30. The method of claim 13, wherein R4 is selected from an alkyl group having 3 to 10 carbon atoms.

31. The method of claim 13, wherein R4 is selected from an alkyl group having 3 to 7 carbon atoms.

32. The method of claim 13, wherein R4 is selected from an alkyl group having 4 to 6 carbon atoms.

33. The method of claim 13, wherein R4 is selected from an aryl group having 6 to 12 carbon atoms.

34. The method of claim 13, wherein R4 is selected from an aryl group having 6 to 10 carbon atoms.

35. The method of claim 13, wherein R4 is selected from aralkyl groups having 7 to 12 carbon atoms.

36. The method of claim 13, wherein R4 is selected from aralkyl groups having 7 to 10 carbon atoms.

37. The method of claim 13, wherein when R4 is selected from an alkyl group, the alkyl group is linear and saturated.

38. The method of claim 13, wherein the halide ion is chloride ion and / or bromide ion.

39. The method of claim 13, wherein the alkyl sulfate is methyl sulfate or ethyl sulfate.

40. The method of claim 9, wherein R1 to R4 are selected so that the sum of the carbon atoms in the quaternary ammonium cation is 6 to 14, or R1 to R4 are selected so that the sum of the carbon atoms in the quaternary ammonium cation is 15 to 30.

41. The method of claim 40, wherein R1 to R4 are selected such that the sum of the carbon atoms in the quaternary ammonium cation is 7 to 14.

42. The method of claim 40, wherein R1 to R4 are selected such that the sum of the carbon atoms in the quaternary ammonium cation is 8 to 13.

43. The method of claim 40, wherein R1 to R4 are selected such that the sum of the carbon atoms in the quaternary ammonium cation is 15 to 28.

44. The method of claim 40, wherein R1 to R4 are selected such that the sum of the carbon atoms in the quaternary ammonium cation is 15 to 24.

45. The method of claim 40, wherein R1 to R4 are selected such that the sum of the carbon atoms in the quaternary ammonium cation is 16 to 22.

46. ​​The method of claim 40, wherein R1 to R4 are selected such that the sum of the carbon atoms in the quaternary ammonium cation is 16 to 20.

47. The method of claim 9, wherein R1 to R4 and X are selected so that the sum of the carbon atoms in the quaternary ammonium salt is 6 to 14, or R1 to R4 and X are selected so that the sum of the carbon atoms in the quaternary ammonium salt is 15 to 30.

48. The method of claim 47, wherein R1 to R4 and X are selected so that the sum of the carbon atoms in the quaternary ammonium salt is 7 to 14.

49. The method of claim 47, wherein R1 to R4 and X are selected so that the sum of carbon atoms in the quaternary ammonium salt is 8 to 13.

50. The method of claim 47, wherein R1 to R4 and X are selected so that the sum of carbon atoms in the quaternary ammonium salt is 15 to 28.

51. The method of claim 47, wherein R1 to R4 and X are selected so that the sum of the carbon atoms in the quaternary ammonium salt is 15 to 24.

52. The method of claim 47, wherein R1 to R4 and X are selected so that the sum of carbon atoms in the quaternary ammonium salt is 16 to 22.

53. The method of claim 47, wherein R1 to R4 and X are selected so that the sum of carbon atoms in the quaternary ammonium salt is 16 to 20.

54. The process according to any one of claims 1 to 8, wherein the catalyst is an organic sulfonate selected from the group consisting of alkylaryl sulfonates, alpha-olefin sulfonates, petroleum sulfonates and naphthalene sulfonates.

55. The process according to any one of claims 1 to 8, comprising the additional step of separating and recovering the organic polyamine and the active hydrogen-containing polyether.

56. The method of claim 55, wherein the active hydrogen-containing polyether is a polyether polyol.

57. The method of any one of claims 1 to 8, wherein the polyurethane is foamed.

58. The method of any one of claims 1 to 8, wherein the polyurethane is reacted with water, the base, and the catalyst under the following conditions: At temperatures between 80°C and 200°C, and / or Reaction time: 1 minute to 14 hours. and / or At atmospheric pressure.

59. The method of claim 58, wherein the reaction temperature is 90°C to 180°C.

60. The method of claim 58, wherein the reaction temperature is 95°C to 170°C.

61. The method of claim 58, wherein the reaction temperature is 100°C to 160°C.

62. The method of claim 58, wherein the reaction time is 1 minute to 12 hours.

63. The method of claim 58, wherein the reaction time is 5 minutes to 12 hours.

64. The method of claim 58, wherein the reaction time is 10 minutes to 12 hours.

65. The method of claim 58, wherein the reaction time is 20 minutes to 12 hours.

66. The method of claim 58, wherein the reaction time is 20 minutes to 11 hours.

67. The method of claim 58, wherein the reaction time is 30 minutes to 10 hours.

68. The method of any one of claims 1 to 8, wherein at least 0.5 wt% catalyst is used, based on the weight of the polyurethane.

69. The method of claim 68, wherein 0.5 to 15 weight percent of a catalyst is used, based on the weight of the polyurethane.

70. The method of claim 68, wherein 1 to 10 weight percent of a catalyst is used based on the weight of the polyurethane.

71. The method of claim 68, wherein 1 to 8 weight percent of a catalyst is used based on the weight of the polyurethane.

72. The method of claim 68, wherein 1 to 7 weight percent of a catalyst is used based on the weight of the polyurethane.

73. The method of claim 68, wherein 2 to 6 weight percent of a catalyst is used based on the weight of the polyurethane.

74. The process of any one of claims 1 to 8, wherein the weight ratio of base to polyurethane is in the range of 0.01 to 50.

75. The method of claim 74, wherein the weight ratio of base to polyurethane is in the range of 0.1 to 25.

76. The method of claim 74, wherein the weight ratio of base to polyurethane is in the range of 0.5 to 20.

77. The process according to any one of claims 1 to 8, wherein an alkaline solution comprising a base and water is used.

78. The method of claim 77, wherein the alkaline solution is a saturated alkaline solution in water.

79. The method of claim 78, wherein the saturated alkaline solution is used in an amount such that the weight ratio of the saturated alkaline solution to the polyurethane is in the range of 0.5 to 25.

80. The method of claim 78, wherein the weight ratio of the saturated alkaline solution to polyurethane is in the range of 0.5 to 15.

81. The method of claim 78, wherein the weight ratio of the saturated alkaline solution to polyurethane is in the range of 1 to 10.

82. The method of claim 78, wherein the weight ratio of the saturated alkaline solution to polyurethane is in the range of 2 to 7.

Images