Method for recovering polyol from polyurethane waste

Abstract

A method for recovering a polyol from polyurethane waste, comprising the following steps: using a degrading agent to degrade polyurethane waste, and then removing the degrading agent to obtain a degradation product; a treating agent represented by formula (I) reacting with the degradation product to obtain a reaction liquid containing a reaction product and a polyol compound; and distilling the reaction liquid to remove the unreacted treating agent and obtain a polyol mixture. The degradation product contains an amine compound and the polyol compound. The reaction product is formed by the amine compound reacting with the treating agent, and the reaction product is in a liquid state at 20-40°C. The method of the present invention allows the amine compound in the degradation product to react to form a liquid product that does not interfere with subsequent treatment. In addition, the unreacted treating agent can also be removed or recovered by means of distillation to obtain a high-purity polyol mixture.

Description

Method for recovering polyol from polyurethane waste Technical Field

[0001] The present invention relates to a method for recycling plastic waste, and in particular to a method for recycling polyol from polyurethane waste. Background Art

[0002] Polyurethane waste is often recycled through chemical degradation to produce degradation products, which are then used to recover polyols or as raw materials for further reactions to produce products such as polyurethane. Chemical degradation methods include pyrolysis, hydrolysis, alcoholysis, alkaline hydrolysis, and aminolysis.

[0003] Regardless of the chemical degradation method used, the degradation products of polyurethane waste after degradation all contain alcohol compounds (such as polyols) and amine compounds, which also causes problems in subsequent applications of these degradation products. For example, when these degradation products are further used to make polyurethane, because the reaction rate of isocyanates and amine compounds is much faster than that of isocyanates and polyols, gels are easily formed during the reaction process, resulting in incomplete overall reaction and hindering the preparation and purification of polyurethane. As can be seen from the above situation, the amine compounds contained in these degradation products must be removed or deactivated to prevent them from affecting subsequent applications.

[0004] Existing patents disclose the use of treatment agents to react with amine compounds to remove amine compounds. For example, Chinese Patent Publication CN1290908C describes a method for treating polyurethane resin. This method decomposes the urethane bonds of the polyurethane resin to produce a resin decomposition substance. Subsequently, an acid anhydride or a compound having one carboxyl group and one hydroxyl group (acetic acid, lactic acid, salicylic acid, acetic anhydride, acetyl chloride, methyl benzoate, butyrolactone, and sodium benzoate) is used as a treatment agent and mixed and reacted with the resin decomposition substance to produce a composition for recycling. This recycling composition can then be further reacted with an epoxy resin or an isocyanate compound to produce a regenerated resin. This patent publication utilizes a screw extruder to decompose and treat the polyurethane resin. Therefore, the reactants, degradation agents, and treatment agents used in the polyurethane resin treatment process cannot be recovered and removed, which may also result in the subsequent regenerated resin containing a large amount of impurities (such as diluents and fillers).

[0005] However, when the treating agent is an acid, the acid reacts with the amines in the decomposition material to produce water and small molecules containing amide groups. This water must be removed before subsequent applications, making the treatment process more time-consuming and complicated. Furthermore, after the polyurethane resin is subsequently produced, the small molecules containing amide groups will disperse in the resin, causing a decrease in the mechanical strength of the resin. When the treating agent is an anhydride, the anhydride and the amines in the decomposition material undergo a ring-opening reaction, which will continue to polymerize and produce a precipitate, hindering the recovery of the polyol or the subsequent production of recycled resin. Secondly, when the amount of anhydride used is relatively large, the remaining anhydride cannot be removed by distillation, which is also not conducive to polyol recovery. When the treating agent is a lactone, if the lactone is used in too high an amount, it will also affect the mechanical strength of the subsequently produced recycled resin.

[0006] As can be seen from the foregoing description, the treatment agents and amine compounds currently used in the industry will form precipitates, which may affect the mechanical strength of the subsequently produced recycled resin. Unreacted treatment agents cannot be effectively removed by distillation. Therefore, the industry still needs to continue to research and develop treatment agents.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a method for recovering polyols from polyurethane waste. The method can effectively react the amine compounds in the degradation products to generate liquid products that do not affect subsequent treatment. The unreacted treatment agent can also be removed or recovered by distillation to obtain a high-purity polyol mixture.

[0009] Therefore, the method for recovering polyol from polyurethane waste of the present invention comprises the following steps:

[0010] Degrading a polyurethane waste material using a degradation agent, and then removing the degradation agent to obtain a degradation product, wherein the degradation product contains an amine compound and a polyol compound;

[0011] reacting a treatment agent represented by formula (I) with the degradation product to obtain a reaction solution containing a reaction product and the polyol compound, wherein the reaction product is formed by the reaction of the amine compound in the degradation product with the treatment agent, and the reaction product is liquid at 20-40° C.; and

[0012] distilling the reaction solution to remove unreacted treating agent, thereby obtaining a polyol mixture containing the reaction product and the polyol compound;

[0013] In formula (I), X is O or NR, and R is hydrogen or a linear alkyl group;

[0014] n is an integer from 2 to 4;

[0015] R1 and R 2 Each represents hydrogen, a linear alkyl group, or a branched alkyl group, and R 1 R can be the same or different, located on different carbons 2 Can be the same or different.

[0016] In some embodiments of the method of the present invention, X is O. In some preferred embodiments of the method of the present invention, the treating agent is selected from ethylene carbonate, propylene carbonate, 1,2-butanediol carbonate, or a combination thereof.

[0017] In some embodiments of the method of the present invention, X is NR. In some preferred embodiments of the method of the present invention, the treating agent is selected from 2-oxazolidinone (R is H), 4-methyl-2-oxazolidinone (R is H), 3-methyl-2-oxazolidinone (R is CH3), or a combination thereof.

[0018] In some embodiments of the method of the present invention, the amount of the treatment agent is calculated according to the following formula:

[0019] Where N is a value between 0.1 and 5.

[0020] In some embodiments of the method of the present invention, the amine compound contained in the degradation product is selected from aliphatic amine compounds, aromatic amine compounds, alcohol amine compounds, or a combination thereof.

[0021] In some embodiments of the method of the present invention, the degradation product and the treatment agent are reacted at a temperature ranging from 50°C to 150°C.

[0022] In some embodiments of the method of the present invention, the reaction solution is distilled at a temperature ranging from 70° C. to 160° C. and a pressure ranging from 0.001 mbar to 100 mbar.

[0023] In some embodiments of the method of the present invention, the degradation agent is selected from amine compounds, alcohol compounds, alcoholamine compounds, or combinations thereof.

[0024] In some embodiments of the present method, the alcohol compound is a polyol compound, and the polyol compound is not removed during the process of removing the degradation agent.

[0025] In some embodiments of the method of the present invention, the reaction product is selected from urea-based polyols, urethane-based polyols, or combinations thereof.

[0026] In some embodiments of the present invention, the polyol mixture has a wavelength in the range of 1730 cm-1 to 1745cm -1 There is an infrared absorption peak between them.

[0027] In some embodiments of the method of the present invention, the polyol mixture comprises urea-based polyol, urethane-based polyol, and polyoxypropylene polyol.

[0028] The present invention has the beneficial effect of using the treating agent represented by formula (I) to react with the amine compound in the degradation product. In addition to preventing severe gelation during the reaction, the resulting reaction product is also liquid. Therefore, during subsequent processing, the reaction liquid does not need to be filtered to remove the reaction product formed by the treating agent and the amine compound. Unreacted treating agent can be removed or recovered by distillation, resulting in a high-purity polyol mixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings:

[0030] FIG1 is a flow chart illustrating the steps of the method of the present invention;

[0031] FIG2 is a spectrum diagram illustrating an infrared absorption spectrum of a degradation product obtained by an embodiment of the method of the present invention; and

[0032] FIG3 is a spectrum diagram illustrating an infrared absorption spectrum of a polyol mixture obtained by an embodiment of the method of the present invention. DETAILED DESCRIPTION

[0033] The method for recovering polyols from polyurethane waste of the present invention comprises the following steps: degrading the polyurethane waste using a degradation agent, followed by removing the degradation agent to obtain a degradation product containing an amine compound and a polyol compound; reacting a treatment agent represented by formula (I) with the degradation product to obtain a reaction liquid containing the reaction product and the polyol compound, wherein the reaction product is formed by the reaction of the amine compound in the degradation product with the treatment agent and is liquid at a temperature of 20 to 40° C.; and distilling the reaction liquid to remove unreacted treatment agent, thereby obtaining a polyol mixture containing the reaction product and the polyol compound.

[0034] The polyurethane waste of the present invention generally refers to any discarded polyurethane material, such as polyurethane foam, polyurethane leather, polyurethane shoe soles, etc. The polyurethane material can be prepared by a polymerization reaction between one or more isocyanate molecules and one or more reactive molecules. The isocyanate molecules can be roughly divided into two categories, namely aromatic diisocyanates or their derivatives and aliphatic diisocyanates or their derivatives. Aromatic diisocyanates include, but are not limited to, toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), xylylene diisocyanate (XDI), dimethyl biphenylene diisocyanate (TODI), and dimethyl methylene diphenyl diisocyanate (DMMDI). In some embodiments of the present invention, the aromatic diisocyanate is toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or paraphenylene diisocyanate (PPDI). Aromatic diisocyanate derivatives include, but are not limited to, toluene diisocyanate dimer (TDI-dimer), toluene diisocyanate trimer (TDI-trimer), and poly(methylene diphenyl diisocyanate) (PMDI). Aliphatic diisocyanates include, but are not limited to, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (H12MDI), 1,4-cyclohexane diisocyanate (CHDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), and methylcyclohexyl isocyanate (HTDI).In some embodiments of the present invention, the aliphatic diisocyanate is isophorone isocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (H12MDI), or 1,4-cyclohexane diisocyanate (CHDI). Aliphatic diisocyanate derivatives include, but are not limited to, hexamethylene diisocyanate dimer (HDI-dimer), hexamethylene diisocyanate trimer (HDI-trimer), hexamethylene diisocyanate biuret (HDI Biuret), and isophorone isocyanate trimer (IPDI-trimer).

[0035] The reactive molecules include, but are not limited to, polyester polyols, polyether polyols, water, diols, polyols, alkamines, diamines, etc. Polyester polyols include, but are not limited to: (1) Adipic acid-based polyester polyols, which are obtained by polycondensation of adipic acid with one or more diols (such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, etc.), with a hydroxyl value ranging from 25 to 200 mgKOH / g and an average molecular weight ranging from 500 to 5000. (2) Aromatic polyester polyols, which are obtained by polycondensation of one or more aromatic dianhydrides [such as phthalic anhydride (PA), terephthalic acid (PTA), isophthalic acid (IPA)] with one or more diols (such as ethylene glycol, propylene glycol, butylene glycol, or diethylene glycol, etc.), with an average molecular weight ranging from 200 to 2000. (3) Polycaprolactone diol is prepared by ring-opening polymerization of ε-caprolactone with one or more diols (such as butanediol, neopentyl glycol, hexanediol, ethylene glycol or diethylene glycol, etc.), with an average molecular weight range of 300-4000. (4) Polycarbonate diol is prepared by transesterification of one or more diols (such as 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 1,5-pentanediol, 3-methylpentanediol, etc.) with one or more alkylene carbonates (such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, etc.), with an average molecular weight range of 500-3000. Polyether polyols include, but are not limited to: (1) polyoxypropylene polyols, which are prepared by polymerization of one or more hydroxyl-containing molecules (such as 1,6-hexanediol, 1,4-butanediol, propylene glycol, ethylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methylpentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, glycerol, trimethylolpropane, ethanolamine, diethanolamine, triethanolamine, etc.) with propylene oxide, with an average molecular weight range of 200-8000. (2) polyoxyethylene polyols, which are prepared by polymerization of ethylene glycol, diethylene glycol or a combination of the two with ethylene oxide, with an average molecular weight range of 200-20000. (3) polytetrahydrofuran polyols, which are prepared by ring-opening polymerization of tetrahydrofuran, with an average molecular weight range of 1000-3000. (4) Polymer polyols, styrene-acrylonitrile grafted polymer polyols based on propylene oxide (PO)-ethylene oxide (EO) copolyether triols, with a hydroxyl value range of 15 to 75. (5) Polytrimethylene ether polyols, made by polymerizing 1,3-propylene glycol, with an average molecular weight range of 600-2500.Examples of diols include, but are not limited to, ethylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, neopentyl glycol, methylpropylene glycol, 1,6-hexanediol, 1,3-propylene glycol, dipropylene glycol, tripropylene glycol, butylethylpropylene glycol, diethylpentanediol, 3-methyl-1,5-pentanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, trimethylpentanediol, cyclohexanediol, and 1,4-dihydroxymethylcyclohexane. Polyols include trimethylolpropane, glycerol, trimethylolethane, 1,2,6-hexanetriol, trishydroxyethyl isocyanurate, pentaerythritol, xylitol, and sorbitol. Examples of the alcohol amines include, but are not limited to, triethanolamine, diethanolamine, triisopropanolamine, methyldiethanolamine, bis(hydroxyisopropyl)aniline, bis(hydroxyisopropyl)-p-toluidine, dihydroxyethylaniline, dihydroxyethyl-p-toluidine, and dihydroxyethyl-m-toluidine. Diamines include, but are not limited to, 3,3'-dichloro-4,4'-diphenylmethanediamine, 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 4,4'-methylenebis(3-chloro-2,6-diethylaniline), 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2,6-diisopropylaniline), 4,4'-methylenebis(2-isopropyl-6-methylaniline), 4,4'-methylenebis(2-isopropyl-6-diethylaniline), 4,4'-methylenebis(2-ethylaniline), toluenediamine, 4,4'-diaminodiphenylmethane, isophoronediamine, diaminodicyclohexylmethane, trimethylhexanediamine, and dimethyldiaminodicyclohexylmethane.

[0036] In the method of the present invention, the degradation of the polyurethane waste can be carried out according to chemical degradation methods well known to those skilled in the art, and any known degradation agent can be used for one or more degradations to break the urethane or urea bonds of the polyurethane and further degrade it into polyols or amines. In some embodiments of the method of the present invention, the degradation agent is selected from amine compounds, alcohol compounds (such as polyol compounds), alcoholamine compounds, or combinations thereof. In a specific embodiment of the method of the present invention, the degradation agent is an alcoholamine compound and an alcohol compound. In a preferred embodiment of the method of the present invention, the alcohol compound is a polyol compound. It should also be noted that when the degradation agent is a polyol compound or contains a polyol compound, the polyol compound is not removed after the degradation reaction using the degradation agent. In other words, during the step of removing the degradation agent, only other compounds other than polyols are removed.

[0037] In some embodiments of the method of the present invention, the method of removing the degradation agent is related to the form of the degradation product, and the form of the degradation product will depend on the molecular weight of the polyol contained in the product to be degraded. When the molecular weight of the polyol contained in the product to be degraded is less than 1,000, the form of the degradation product is liquid. When the molecular weight of the polyol contained in the product to be degraded is between 1,000 and 3,000, the form of the degradation product is paste-like. When the molecular weight of the polyol contained in the product to be degraded is greater than 3,000, the form of the degradation product is a non-fluid fat state. Depending on the different forms mentioned above, the method of removing the degradation agent is also different. The liquid or paste-like degradation product and the degradation agent will be separated into layers, and sampling can be carried out in layers. The degradation agent can be directly poured out of the non-fluid fat-like degradation product.

[0038] The degradation products obtained after the polyurethane waste is degraded contain one or more amine compounds and one or more polyol compounds. In some embodiments of the method of the present invention, the amine compound is selected from aliphatic amine compounds, aromatic amine compounds, alcohol amine compounds, or combinations thereof.

[0039] The treating agent used in the method of the present invention is shown in the following formula (I):

[0040] In formula (I), X is O or NR, and R is hydrogen or a linear alkyl group;

[0041] n is an integer from 2 to 4;

[0042] R 1 and R 2 Each represents hydrogen, a linear alkyl group, or a branched alkyl group, and R 1 R can be the same or different, located on different carbons 2 Can be the same or different.

[0043] In some embodiments of the method of the present invention, R 1 and R 2 Each is a linear or branched alkyl group, and its carbon number ranges from 1 to 10. In some preferred embodiments of the method of the present invention, the carbon number of the linear or branched alkyl group ranges from 1 to 5. In a specific embodiment of the method of the present invention, the carbon number of the linear or branched alkyl group ranges from 1 to 3.

[0044] In some embodiments of the method of the present invention, the treating agent is represented by the following formula (I-1):

[0045] In formula (I-1), X is O, n, R 1 and R 2 The definition of is the same as that of formula (I).

[0046] In some preferred embodiments of the method of the present invention, the treating agent is selected from ethylene carbonate, propylene carbonate, 1,2-butanediol carbonate or a combination thereof.

[0047] In some embodiments of the method of the present invention, X is NR, as shown in the following formula (I-2):

[0048] n and R in formula (I-2) 1 and R 2 The definition of is the same as that of formula (I). In some embodiments of the method of the present invention, R is hydrogen or methyl.

[0049] In some preferred embodiments of the method of the present invention, the treating agent is selected from 2-oxazolidinone, 4-methyl-2-oxazolidinone, 3-methyl-2-oxazolidinone or a combination thereof.

[0050] In a specific example of the present invention, the treating agent is selected from ethylene carbonate, propylene carbonate, 1,2-butanediol carbonate, 2-oxazolidinone, 4-methyl-2-oxazolidinone, 3-methyl-2-oxazolidinone, or a combination thereof.

[0051] The reaction temperature and pressure of the degradation product and the treatment agent can be adjusted according to actual needs. In some embodiments of the present method, the degradation product and the treatment agent are reacted at a temperature ranging from 50°C to 150°C. In some preferred embodiments of the present method, the temperature range is from 90°C to 150°C. In one embodiment of the present invention, the temperature is 120°C; in another embodiment of the present invention, the temperature is 90°C; and in yet another embodiment of the present invention, the temperature is 130°C.

[0052] The amount of the treatment agent is adjusted mainly based on the amine compounds in the degradation product. In some embodiments of the method of the present invention, the amount of the treatment agent is calculated according to the following formula:

[0053] Wherein N is a value between 0.1 and 5. In some embodiments of the method of the present invention, N is a value between 0.3 and 1.5.

[0054] During the reaction between the treatment agent and the degradation product, the treatment agent undergoes a ring-opening reaction with the amine compound in the degradation product to produce a reaction product. This reaction product is liquid at room temperature (20-40°C), meaning that the reaction between the treatment agent and the amine compound does not produce a precipitate and does not affect the purity of the polyol mixture or subsequent applications. In some embodiments of the present method, the reaction product is selected from a urea-based polyol, a urethane-based polyol, or a combination thereof.

[0055] The temperature and pressure of the reaction solution during the distillation step can be adjusted depending on the treatment agent used. In some embodiments of the present method, the reaction solution is distilled at a temperature ranging from 70° C. to 160° C. and a pressure ranging from 0.001 mbar to 100 mbar. In some preferred embodiments of the present method, the reaction solution is distilled at a temperature ranging from 75° C. to 150° C. and a pressure ranging from 0.01 mbar to 20 mbar.

[0056] The reaction solution may be optionally filtered before distillation to remove insoluble matter and further improve the purity of the polyol mixture.

[0057] The resulting polyol mixture contains the reaction product and the polyol compound. In some embodiments of the present method, the resulting polyol mixture includes urea polyol, urethane polyol, and polyoxypropylene polyol. It should be noted that when the polyurethane waste structure contains alkyl glycols (such as ethylene glycol, 1,4-butanediol, etc.), the polyol compound obtained after degradation of the polyurethane waste will also contain alkyl glycols, and the resulting polyol mixture will also contain alkyl glycols.

[0058] In some embodiments of the method of the present invention, the polyol mixture prepared has a wavelength in the range of 1730 cm -1 to 1745cm -1 In the embodiment of the present invention, the polyol mixture has an infrared absorption peak at 1736 cm -1 There is an infrared absorption peak at .

[0059] The polyol mixture obtained by the method of the present invention can be subsequently used to prepare thermosetting polyurethane and the like.

[0060] Example

[0061] The present invention will be further described with reference to the following examples. However, it should be understood that these examples are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

[0062] Test method:

[0063] The amine value, hydroxyl value and viscosity of the following examples were tested according to the following methods:

[0064] 1. Amine value (mgKOH / g): tested according to standard method ISO 25761:2014.

[0065] 2. Hydroxyl value (mgKOH / g): tested according to standard method ASTM D4274.

[0066] 3. Viscosity (cP): Tested according to ISO 3219 at 25°C.

[0067] Example 1 Preparation of degradation products

[0068] 1500 grams of soft PU foam (containing 60 wt% polyol) was mixed with 3000 grams of a first degradation agent and subjected to a first degradation reaction at 135°C to obtain a solid-liquid decomposition reaction solution (containing a fatty product and a reaction mixture). The first degradation agent included an alcoholamine compound, which refers to a polyfunctional compound having both hydroxyl (-OH) and amino (-NH2 and -NHR) functional groups, such as diethanolamine, bis(hydroxyisopropyl)aniline, bis(hydroxyisopropyl)-p-toluidine, dihydroxyethylaniline, dihydroxyethyl-p-toluidine, or dihydroxyethyl-m-toluidine. Approximately 3000 grams of the first degradation reaction mixture (containing the first degradation agent, urea diol, and toluenediamine) was then removed, and 1500 grams of the fatty product was mixed with 150 grams of a second degradation agent (glycerol) and subjected to a second degradation reaction at 150°C to obtain a degradation product.

[0069] [Property Analysis]

[0070] 1. The degradation products were analyzed using an infrared spectrometer (IR, manufactured by PerkinElmer, model Spectrum 100), and the results are shown in Figure 2. As can be seen from Figure 2, the degradation products contain amine compounds (toluenediamine) and polyol compounds (polyoxypropylene polyol).

[0071] 2. The amine value of the degradation product is 100 mgKOH / g, and the estimated output of the polyol it contains is 800 grams.

[0072] Example 2: Recovery of polyols using ethylene carbonate as a treating agent

[0073] 100 g of the degradation product from Example 1 was placed in a reaction kettle. 31.4 g (N=2) of an ethylene carbonate treatment agent was slowly added to the kettle at 25°C. The degradation product and ethylene carbonate were stirred and mixed for 0.5 hours to obtain a mixed solution. The mixture was then stirred and reacted at 120°C. During the reaction, the ethylene carbonate signal in the mixture was continuously monitored using IR. The reaction was terminated until the signal remained constant, yielding a reaction solution.

[0074] Observation of the reaction solution with the naked eye revealed that the reaction solution was in a liquid state and did not contain any precipitate, indicating that the reaction product (formed by the reaction of ethylene carbonate and the amine compound) contained in the reaction solution was also in a liquid state and did not precipitate in a solid state.

[0075] The reaction solution was distilled at a temperature of 150° C. and a pressure of 20 mbar for 2 hours to remove unreacted ethylene carbonate, and finally 110.2 g of a polyol mixture (containing urethane polyol and polyoxypropylene polyol) was obtained.

[0076] [Property Analysis]

[0077] The polyol mixture of Example 2 had a hydroxyl value of 95 mgKOH / g, a viscosity of 1200 cP, and a recovery rate of 110%.

[0078] Example 3: Recovery of polyols using propylene carbonate as a treating agent

[0079] 100 g of the degradation product from Example 1 was placed in a reaction kettle. 27.2 g (N = 1.5) of a propylene carbonate treatment agent was slowly added to the kettle at 25°C. The degradation product and propylene carbonate were stirred and mixed for 0.5 hours to obtain a mixed solution. The mixture was then stirred and reacted at 120°C. During the reaction, the propylene carbonate signal in the mixture was continuously monitored using IR. The reaction was terminated until the signal remained constant, yielding a reaction solution.

[0080] The reaction solution was distilled at a temperature of 150° C. and a pressure of 20 mbar for 2 hours to remove unreacted propylene carbonate, and finally 119.5 g of a polyol mixture (containing urethane polyol and polyoxypropylene polyol) was obtained.

[0081] [Property Analysis]

[0082] 1. The polyol mixture was analyzed using an infrared spectrometer, and the results are shown in Figure 3. Comparing Figure 2 with Figure 3, it can be found that Figure 3 has a wavelength of 1736 cm -1 There is a specific infrared absorption peak.

[0083] 2. The polyol mixture of Example 3 had a hydroxyl value of 93 mgKOH / g, a viscosity of 1100 cP, and a recovery rate of 120%.

[0084] Example 4: Recovery of polyols using 1,2-butanediol carbonate as a treating agent

[0085] 100 g of the degradation product from Example 1 was placed in a reaction kettle. 20.6 g (N=1) of 1,2-butanediol carbonate treating agent was slowly added to the kettle at 25°C. The degradation product and 1,2-butanediol carbonate were stirred and mixed for 0.5 hours to obtain a mixed solution. The mixture was then stirred and reacted at 120°C. During the reaction, the 1,2-butanediol carbonate signal in the mixture was continuously monitored using IR. The reaction was terminated until the signal remained constant, yielding a reaction solution.

[0086] The reaction solution was distilled at 150° C. and 20 mbar for 2 hours to remove unreacted 1,2-butanediol carbonate, thereby obtaining 105.5 g of a polyol mixture (containing urethane polyol and polyoxypropylene polyol).

[0087] [Property Analysis]

[0088] The polyol mixture of Example 4 had a hydroxyl value of 100 mgKOH / g, a viscosity of 1020 cP, and a recovery rate of 105%.

[0089] Example 5: Recovery of polyols using 2-oxazolidinone as a treating agent

[0090] 100.0 g of the degradation product from Example 1 was placed in a reaction kettle. 47.0 g (N=3) of a 2-oxazolidinone treatment agent was slowly added to the kettle at 25°C. The degradation product and 2-oxazolidinone were stirred and mixed for 0.5 hours to obtain a mixed solution. The mixture was then stirred and reacted at 120°C. During the reaction, the 2-oxazolidinone signal in the mixture was continuously monitored by IR. The reaction was terminated until the signal remained constant, yielding a reaction solution.

[0091] The reaction solution was distilled at 120° C. and 20 mbar for 2 hours to remove unreacted 2-oxazolidinone, and finally 110.5 g of a polyol mixture (containing urea polyol and polyoxypropylene polyol) was obtained.

[0092] [Property Analysis]

[0093] The polyol mixture of Example 5 had a hydroxyl value of 96 mgKOH / g, a viscosity of 1150 cP, and a recovery rate of 110.5%.

[0094] Example 6: Recovery of polyols using 4-methyl-2-oxazolidinone as a treating agent

[0095] 100.0 g of the degradation product from Example 1 was placed in a reaction kettle. 27.2 g (N=1.5) of a 4-methyl-2-oxazolidinone treatment agent was slowly added to the kettle at 25°C. The degradation product and 4-methyl-2-oxazolidinone were stirred and mixed for 0.5 hours to obtain a mixed solution. The mixture was then stirred and reacted at 90°C. During the reaction, the signal change of 4-methyl-2-oxazolidinone in the mixture was continuously monitored by IR. The reaction was terminated until the signal remained constant, yielding a reaction solution.

[0096] The reaction solution was distilled at 75° C. and 20 mbar for 2 hours to remove unreacted 4-methyl-2-oxazolidinone, and 108.0 g of a polyol mixture (containing urea polyol and polyoxypropylene polyol) was obtained.

[0097] [Property Analysis]

[0098] The polyol mixture of Example 6 had a hydroxyl value of 97 mgKOH / g, a viscosity of 1050 cP, and a recovery rate of 108%.

[0099] Example 7: Recovery of polyols using 3-methyl-2-oxazolidinone as a treating agent

[0100] 100.0 g of the degradation product from Example 1 was placed in a reaction kettle. 36.0 g (N=2) of a 3-methyl-2-oxazolidinone treatment agent was slowly added to the kettle at 25°C. The degradation product and 3-methyl-2-oxazolidinone were stirred and mixed for 0.5 hours to obtain a mixed solution. The mixture was then stirred and reacted at 130°C. During the reaction, the signal change of 3-methyl-2-oxazolidinone in the mixture was continuously monitored by IR. The reaction was terminated until the signal remained constant, yielding a reaction solution.

[0101] The reaction solution was distilled at 150° C. and 20 mbar for 2 hours to remove unreacted 3-methyl-2-oxazolidinone, and 102.2 g of a polyol mixture (containing urea polyol and polyoxypropylene polyol) was obtained.

[0102] [Property Analysis]

[0103] The polyol mixture of Example 7 had a hydroxyl value of 95 mgKOH / g, a viscosity of 1000 cP, and a recovery rate of 102.2%.

[0104] The above examples demonstrate that the method of the present invention utilizes a treatment agent such as Formula (I) to react with an amine compound in the degradation product. In addition to the resulting reaction product being in a liquid state and not affecting subsequent applications, the reaction liquid does not require filtration to remove the reaction product formed by the reaction of the treatment agent and the amine compound during subsequent processing. Furthermore, the treatment agent selected in the present invention can be removed or recovered by vacuum distillation to obtain a high-purity polyol mixture. Compared to the prior art method of removing the treatment agent by washing with water, the method of the present invention does not require the consumption of large amounts of water to remove or recover the unreacted treatment agent.

[0105] However, the above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the claims and the contents of the patent specification of the present invention are still within the scope of the patent of the present invention.

Claims

1. A method for recovering polyols from polyurethane waste, Features: It includes the following steps: Degrading polyurethane waste using a degradation agent, and then removing the degradation agent to obtain a degradation product, wherein the degradation product contains an amine compound and a polyol compound; reacting a treatment agent as shown in formula (I) with the degradation product to obtain a reaction solution containing the reaction product and the polyol compound, wherein the reaction product is formed by the reaction of the amine compound in the degradation product with the treatment agent, and the reaction product is in liquid state at 20-40° C.; and Distilling the reaction solution to remove unreacted treating agent, thereby obtaining a polyol mixture containing the reaction product and the polyol compound; In formula (I), X is O or NR, and R is hydrogen or a linear alkyl group; n is an integer from 2 to 4; R 1 and R 2 Each represents hydrogen, a straight-chain alkyl group, or a branched-chain alkyl group, and R located on different carbon atoms 1 Can be the same or different, located on different carbon R 2 Can be the same or different.

2. The method according to claim 1, Features: The X is O.

3. The method according to claim 2, Features: The treating agent is selected from ethylene carbonate, propylene carbonate, 1,2-butanediol carbonate or a combination thereof.

4. The method according to claim 1, Features: The X is NR.

5. The method according to claim 4, Features: The treating agent is selected from 2-oxazolidinone, 4-methyl-2-oxazolidinone, 3-methyl-2-oxazolidinone or a combination thereof.

6. The method according to claim 1, Features: The dosage of the treatment agent is calculated according to the following formula: The amount of treatment agent (g) = the weight of the degradation product (g) × (the amine value of the degradation product Where N is a value between 0.1 and 5.

7. The method according to claim 1, Features: The amine compounds contained in the degradation products are selected from aliphatic amine compounds, aromatic amine compounds, alcohol amine compounds, or a combination thereof.

8. The method according to claim 1, Features: The degradation product reacts with the treating agent at a temperature ranging from 50°C to 150°C.

9. The method according to claim 1, Features: The reaction solution is distilled at a temperature ranging from 70° C. to 160° C. and a pressure ranging from 0.001 mbar to 100 mbar.

10. The method according to claim 1, Features: The degradation agent is selected from amine compounds, alcohol compounds, alcoholamine compounds, or a combination thereof.

11. The method according to claim 10, Features: The alcohol compound is a polyol compound, and the polyol compound is not removed during the process of removing the degradation agent.

12. The method according to claim 1, Features: The reaction product is selected from urea-based polyols, urethane-based polyols or combinations thereof.

13. The method according to claim 1, Features: The polyol mixture falls in the wave number range of 1730 cm -1 Up to 1745cm -1 There is an infrared absorption peak in between.

14. The method according to claim 1, Features: The polyol mixture comprises urea-based polyol, urethane-based polyol and polyoxypropylene polyol.

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