Method for producing recycled polyol and recycled polyol

Abstract

Provided is a technique for obtaining a regenerated polyol. A method for producing a regenerated polyol is a method in which an organic carboxylic acid having two or more carboxyl groups and / or an acid anhydride thereof is added to a decomposition-treated product obtained by treating a polyurethane resin with a decomposition agent, the ratio of the molar amount of the carboxyl groups to the total molar amount of amino groups in the decomposition-treated product and hydroxyl groups of the decomposition agent is 0.5 or greater and 1.0 or less, and heating is performed to 150°C or higher, to obtain a regenerated polyol.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a recycled polyol and the recycled polyol itself.

[0002] This application claims priority based on Japanese Patent Application No. 2024-58925, filed on April 1, 2024, the entire contents of which are incorporated herein by reference. Background Technology

[0003] Patent Document 1 describes a method for purifying polyols, which involves adding at least one organic dicarboxylic acid or its anhydride selected from the group consisting of oxalic acid, succinic acid, maleic acid, and maleic anhydride to a polyol containing a polyamine, followed by removal of the precipitate. The method in Patent Document 1 describes that, in order to precipitate the polyamine as an organic dicarboxylic acid salt, heating to 50–140°C under a nitrogen atmosphere is preferred; in the example, heating is performed at 120°C.

[0004] Patent Document 2 discloses a method for manufacturing a resin composition, characterized by decomposing a polyurethane resin with a decomposing agent having unsaturated carbon bonds. It also describes that the resulting resin composition can be formulated with various additives as needed for use as a molding material.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2000-247917 Patent Document 2: Japanese Patent Application Publication No. 2005-8784 Summary of the Invention The problem the invention aims to solve The technology in Patent Document 1 causes the polyamine to precipitate as an unstable salt, which may lead to dissociation in the polyol or after removal. Furthermore, because the process in Patent Document 1 is performed at a low temperature of around 120°C, carboxyl groups are prone to remain, potentially resulting in the formation of harmful aromatic diamines or a decrease in the pH of the polyol. The technology in Patent Document 2 cannot recover polyols from polyurethane decomposition products for use as recycled feedstock.

[0006] This disclosure is made in view of the foregoing and aims to solve at least one of the aforementioned problems. This disclosure may be implemented in the following ways.

[0007] means for solving problems [1] A method for manufacturing a recycled polyol, wherein an organic carboxylic acid having two or more carboxyl groups and / or its anhydride are added to a decomposition product obtained by treating a polyurethane resin with a decomposition agent, such that the molar amount of the carboxyl groups is 0.5 or more and 1.0 or less than the total molar amount of the amino groups and the hydroxyl groups of the decomposition agent in the decomposition product, and the mixture is heated to 150°C or higher to obtain a recycled polyol.

[0008] Invention Effects According to this disclosure, at least one of the above-mentioned problems can be solved. For example, according to this disclosure, a technique for obtaining high-quality recycled polyols can be provided. Attached Figure Description

[0009] Figure 1 It is a diagram showing the melting point, boiling point, and structural formula of a polycarboxylic acid or anhydride. Detailed Implementation

[0010] Preferred examples of this disclosure are shown herein.

[0011] [2] A method for manufacturing a regenerated polyol as described in [1], wherein the decomposition product is obtained by alcoholysis.

[0012] [3] A regenerated polyol is obtained by adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride to a decomposition product obtained by treating polyurethane resin with a decomposition agent, wherein the amine value of the regenerated polyol is less than 55 mg KOH / g and the pH of the regenerated polyol is greater than 5.5.

[0013] [4] The regenerated polyol as described in [3], wherein the decomposition product is obtained by alcoholysis.

[0014] The present disclosure will now be explained in detail. Furthermore, in this specification, whenever the numerical range is indicated by "~", it includes both the lower and upper limits, unless otherwise specified. For example, the expression "10~20" includes both the lower limit "10" and the upper limit "20". That is, "10~20" has the same meaning as "more than 10 and less than 20". Additionally, in this specification, the upper and lower limits of each numerical range can be arbitrarily combined.

[0015] 1. Method for manufacturing recycled polyols A method for manufacturing a recycled polyol involves adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride to a decomposed product obtained by treating polyurethane resin with a decomposition agent, such that the molar amount of the carboxyl groups is 0.5 or more and 1.0 or less than the total molar amount of the amino groups and the hydroxyl groups of the decomposition agent in the decomposed product, and heating to 150°C or higher to obtain a recycled polyol.

[0016] (1) Polyurethane resin There are no particular limitations on the polyurethane resin used in the manufacturing process of recycled polyols. The polyurethane resin may be, for example, polyurethane foam. The polyurethane foam can be any of flexible polyurethane foam, semi-rigid polyurethane foam, and rigid polyurethane foam. The polyurethane foam can be a continuous bubble structure or an independent bubble structure. The polyurethane foam can be pulverized into a specified size. Alternatively, the polyurethane foam can be cut into specified sizes. The polyurethane foam may also be, for example, scrap material discharged during the manufacturing process of polyurethane foam, or used polyurethane foam that is planned for disposal.

[0017] (2) Decomposing agent There are no particular limitations on the decomposing agent, as long as it can chemically decompose and liquefy the polyurethane bonds. From the viewpoint of reactivity or cost, the decomposing agent is preferably selected from one or more compounds consisting of hydroxyl groups and amine compounds.

[0018] Compounds containing hydroxyl groups are preferably selected from one or more of the group consisting of diethylene glycol, glycerol, ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, and polyethylene glycol. These compounds containing hydroxyl groups can be used alone or in combination of two or more.

[0019] The amine compounds are preferably selected from one or more of the group consisting of ethylenediamine, tetramethylenediamine, hexamethylenediamine, propylenediamine, 2-ethylhexylamine, isopropanolamine, 2-(2-aminoethylamino)ethanol, 2-amino-2-hydroxymethyl-1,3-propanediol, ethylaminoethanol, aminobutanol, n-propylamine, di-n-propylamine, n-pentylamine, isobutylamine, methyldiethylamine, monoethanolamine, diethanolamine, triethanolamine, cyclohexylamine, piperazine, piperidine, aniline, toluidine, benzylamine, phenylenediamine, xylenediamine, chloroaniline, pyridine, methylpyridine, N-methylmorpholine, ethylmorpholine, and pyrazole. These amine compounds can be used alone or in mixtures of two or more.

[0020] The decomposition agent preferably contains a compound having hydroxyl groups. That is, the decomposition product is preferably obtained by alcoholysis. The hydroxyl-containing compound that can be used as a decomposition agent typically has a molecular weight smaller than that of the polyol used as the raw material for the polyurethane resin being decomposed. The molecular weight of the hydroxyl-containing compound is, for example, 62 or more and 800 or less, or it can be 600 or less, 400 or less, or 200 or less. In the following description, compounds with the above-mentioned molecular weights are also referred to as low-molecular-weight hydroxyl-containing compounds. When the decomposition agent contains a hydroxyl-containing compound, by adding a polycarboxylic acid and / or its anhydride, the hydroxyl-containing compound used as the decomposition agent can be converted into an ester compound. Therefore, it is possible to better reduce the amount of low-molecular-weight hydroxyl-containing compounds in the recycled polyol.

[0021] There is no particular limitation on the amount of decomposing agent added. From the viewpoint of fully decomposing polyurethane resin, the amount of decomposing agent added is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, relative to 100 parts by mass of polyurethane resin. Considering the impact on reactivity or physical properties when polyurethane resin decomposition products are reused as polyurethane resin raw materials, the above-mentioned amount of decomposing agent added is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. From these viewpoints, the above-mentioned amount of decomposing agent added is preferably 1 part by mass and 100 parts by mass or less, more preferably 5 parts by mass and 50 parts by mass or less, and even more preferably 8 parts by mass and 40 parts by mass or less.

[0022] (3) Decomposition catalyst The decomposition agent can be used in conjunction with the decomposition catalyst. There are no particular limitations on the decomposition catalyst. Preferably, the decomposition catalyst is the catalyst used in the formation of the polyurethane resin.

[0023] The decomposition catalyst is preferably selected from 1,8-diazabicyclo[5.4.0]undec-7-ene, triethylamine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropane-1,3-diamine, N,N,N',N'-tetramethylhexane-1,6-diamine, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N',N",N"-pentamethyldipropylenetriamine, tetramethylguanidine, triethylenediamine, N,N'-dimethylpiperazine, N-methyl,N'-(2-dimethylamino)ethylpiperazine, N-methylmorpholine, N-(N', One or more of the following are included in the group consisting of N'-dimethylaminoethyl)-morpholine, 1,2-dimethylimidazolium, hexamethylenetetramine, dimethylaminoethanol, dimethylaminoethoxyethanol, N,N,N'-trimethylaminoethylethanolamine, N-methyl-N'-(2-hydroxyethyl)-piperazine, N-(2-hydroxyethyl)morpholine, bis(2-dimethylaminoethyl) ether, ethylene glycol bis(3-dimethyl)aminopropyl ether, stannous octanoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin thiolate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiolate, dioctyltin thiocarboxylate, lead octanoate, potassium acetate, and potassium octanoate. These decomposition catalysts can be used alone or in combination of two or more.

[0024] There is no particular limitation on the amount of decomposition catalyst added. From the viewpoint of fully decomposing polyurethane resin, the amount of decomposition catalyst added is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and may also be 1 part by mass or more, relative to 100 parts by mass of polyurethane resin. Considering the impact on reactivity or physical properties when the decomposition products of polyurethane resin are reused as raw materials for polyurethane resin, the amount of the above-mentioned decomposition catalyst added is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. From these viewpoints, the amount of the above-mentioned decomposition catalyst added is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0025] (4) Other components The decomposition product can also be obtained by adding components other than the decomposition agent and decomposition catalyst described above (also referred to as other components). The polyurethane decomposition composition described above may further contain components other than the decomposition agent and catalyst (also referred to as other components). For example, from the perspective of obtaining a decomposition product in a single-phase state, the decomposition product can be further obtained by adding a high molecular weight polyol with a number average molecular weight of 1000 or more.

[0026] The high molecular weight polyol is preferably selected from one or more of polyether polyols, polyester polyols, and polyether ester polyols. The high molecular weight polyol can also be the raw material polyol for the recycled polyurethane resin using recycled polyols as described below. By using the raw material polyol for the recycled polyurethane resin, the influence of components in the recycled polyol during the preparation of the recycled polyurethane resin can be reduced.

[0027] There is no particular limitation on the amount of high molecular weight polyol added. From the viewpoint of obtaining a single-phase polyurethane decomposition product, the amount of high molecular weight polyol added relative to 100 parts by mass of the decomposed product, i.e., polyurethane resin, is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more. Furthermore, when using a polyol derived from recycled polyurethane resin, from the viewpoint of obtaining a low-viscosity polyurethane decomposition product, the aforementioned amount of high molecular weight polyol added can be 20 parts by mass or more, 25 parts by mass or more, or 30 parts by mass or more. The aforementioned amount of high molecular weight polyol added is generally 200 parts by mass or less, and can be 150 parts by mass or less or 80 parts by mass or less. The aforementioned amount of high molecular weight polyol added is preferably 1 part by mass or more and 200 parts by mass or less, and can also be a range that appropriately combines the aforementioned upper and lower limits.

[0028] (5) Decomposition treatment products The decomposition product is obtained by treating polyurethane resin with a decomposition agent. Alternatively, the decomposition product can be obtained by treating polyurethane resin with both a decomposition agent and a decomposition catalyst.

[0029] There are no particular restrictions on the decomposition conditions of polyurethane resin. However, from the viewpoint of increasing the decomposition rate, it is recommended to heat the polyurethane resin and the decomposing agent together. It is also recommended to stir the mixture of polyurethane resin and the decomposing agent while heating them together.

[0030] From the viewpoint of simultaneously increasing the decomposition rate and suppressing the decomposition of polyols, which are polyurethane decomposition products derived from raw material polyols, the decomposition treatment temperature is preferably 80°C or higher and 300°C or lower, more preferably 100°C or higher and 270°C or lower, and even more preferably 150°C or higher and 250°C or lower.

[0031] The decomposition treatment time can be, for example, 10 minutes or more but less than 24 hours, or 30 minutes or more but less than 10 hours. The endpoint of the decomposition treatment time can be set appropriately based on the size of the polyurethane resin, whether or not stirring is used, etc., while monitoring the progress of polyurethane resin decomposition. In addition, for example, when decomposing polyurethane resin at a temperature above room temperature (e.g., 25°C) and below 80°C, the decomposition treatment time can be set to more than 24 hours.

[0032] The decomposition product may contain, for example, polyols derived from polyurethane resin raw material polyols and amine compounds derived from raw material isocyanates. In addition, the decomposition product may contain hydroxyl-containing compounds added as decomposition agents, flame retardants contained in the polyurethane resin, decomposition catalysts, and other additives.

[0033] There are no particular restrictions on the state of the decomposition product. Preferably, the decomposition product is in a single-phase state where the phase containing the polyol (hereinafter also referred to as the polyol phase) and the phase containing the amine compound (hereinafter also referred to as the amine phase) are not separated. When the decomposition product is obtained by alcoholysis using a specific type and amount of decomposition agent, it is preferable to obtain the decomposition product in a single-phase state. Furthermore, "the decomposition product is in a single-phase state" means that the liquid phase containing the polyol from the raw material polyol and the liquid phase containing the amine compound from the raw material isocyanate are not clearly separated, but are in a homogeneous state. The single-phase decomposition product may contain solid components found in polyurethane resin. Examples of solid components found in polyurethane resin include, for example, components from polymer polyols containing polymers such as styrene or acrylonitrile, and flame retardants such as phosphorus-based flame retardants and halogen-based flame retardants.

[0034] When the decomposition product is in a single-phase state, almost the entire amount of the decomposition product can be used as a recycled raw material. However, the reactivity of amine compounds with isocyanates used in the manufacture of polyurethane foam is too high, making it difficult to use directly as a recycled polyol. Furthermore, the presence of low-molecular-weight hydroxyl compounds in the recycled polyol may affect the physical properties of the polyurethane foam obtained from it, such as its hardness. In particular, if the amount of low-molecular-weight hydroxyl compounds is high, it is unsuitable for manufacturing flexible polyurethane foam. That is, if the recycled polyol contains a large amount of amine compounds and low-molecular-weight hydroxyl compounds, the quality of the recycled polyol cannot be guaranteed. According to the technology disclosed herein, by converting amine compounds and low-molecular-weight hydroxyl compounds into less reactive compounds, a higher quality recycled polyol can be obtained.

[0035] (6) Organic carboxylic acids and / or their anhydrides (polycarboxylic acids and / or their anhydrides) having two or more carboxyl groups There are no particular restrictions on polycarboxylic acids and / or their anhydrides.

[0036] The number of carboxyl groups in the polycarboxylic acid and / or its anhydrides is preferably 2 or more and 4 or less, more preferably 2 or 3.

[0037] Polycarboxylic acids and / or their anhydrides can be aromatic carboxylic acids or aliphatic carboxylic acids.

[0038] The polycarboxylic acids and / or their anhydrides preferably have 2 or more and 20 or less carbon atoms, more preferably 2 or more and 12 or less, and even more preferably 3 or more and 10 or less. The number of carbon atoms mentioned here also includes the number of carbon atoms contained in the carboxyl group.

[0039] The boiling point or decomposition temperature of polycarboxylic acids and / or their anhydrides at atmospheric pressure is preferably 135°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. There is no particular limitation on the upper limit of the above-mentioned boiling point or decomposition temperature, which is generally below 500°C.

[0040] The melting point of polycarboxylic acids and / or their anhydrides at atmospheric pressure is preferably below 300°C, more preferably below 250°C, and even more preferably below 220°C. The lower limit of the above melting point is not particularly limited, and is generally above 20°C, but can be above 50°C, above 80°C, or above 95°C.

[0041] The polycarboxylic acids and / or their anhydrides are preferably selected from one or more of the group consisting of oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, dipropylmalonic acid, maleic acid, trans-3-hexenediaic acid, itaconic acid, phthalic acid, malic acid, L(+)-tartaric acid, citric acid, trans-aconitic acid, 2,3-pyridinedicarboxylic acid, succinic anhydride, maleic anhydride, phthalic anhydride, and trimellitic anhydride. The melting point, boiling point, and structural formula of the above compounds are as follows: Figure 1 As shown. Furthermore, compounds with an empty boiling point column or a "-" sign have a boiling point or decomposition temperature above 150°C.

[0042] (7) The ratio of the molar amount of carboxyl groups to the total molar amount of amino groups and hydroxyl groups of the decomposition agent in the decomposition product. The method for manufacturing recycled polyols involves adding polycarboxylic acids and / or their anhydrides to a decomposed product obtained by treating polyurethane resin with a decomposition agent, such that the molar ratio of carboxyl groups to the total molar ratio of amino groups in the decomposition product and hydroxyl groups in the decomposition agent is 0.5 or more and 1.0 or less. The molar ratio of carboxyl groups to the total molar ratio of amino groups in the decomposition product and hydroxyl groups in the decomposition agent is preferably 0.55 or more and 0.9 or less, more preferably 0.6 or more and 0.8 or less.

[0043] When the ratio of the molar amount of carboxyl groups to the total molar amount of amino groups in the decomposition product and hydroxyl groups in the decomposition agent is within the above-mentioned range, amine compounds in the decomposition product can be better converted into amide compounds (including imide compounds). Furthermore, when within the above-mentioned range, compounds with hydroxyl groups added as decomposition agents can be better converted into ester compounds. Further, when within the above-mentioned range, the pH, total amine value, and hydroxyl value of the regenerated polyol are easily optimized, and the amount of solid components contained in the regenerated polyol can be reduced.

[0044] The molar amount of amino groups in the decomposition product can be calculated by determining the total amine value according to JIS K 1557.

[0045] The molar amount of the decomposing agent added when obtaining the decomposition product can be calculated by multiplying the molar amount of the decomposing agent by the number of hydroxyl groups.

[0046] The sum of the product of the molar amount of the added polycarboxylic acid and the number of carboxyl groups and the product of the molar amount of the added acid anhydride and twice the number of acid anhydride groups is taken as the molar amount of the carboxyl group.

[0047] (8) Heating The method for producing regenerated polyols involves adding a specified amount of polycarboxylic acid and / or its anhydride to the decomposition product and heating it to 150°C or higher. From the viewpoint of precipitate formation, a heating temperature of 150°C or higher is acceptable, but it can also be 160°C or higher, 170°C or higher, or 180°C or higher. There is no particular upper limit to the heating temperature. Regarding the upper limit of the heating temperature, from the viewpoint of inhibiting the vaporization or decomposition of organic carboxylic acids, it can be, for example, below 280°C, but it can also be below 260°C, 240°C or lower, or 220°C or lower.

[0048] The aforementioned heating can also utilize the residual heat from the decomposition process of polyurethane resin. For example, by adding polycarboxylic acids and / or their anhydrides before the heated decomposition product is cooled to room temperature, and then performing the aforementioned heating, it is possible to shorten the heating and cooling time and reduce energy consumption such as electricity when manufacturing recycled polyols.

[0049] The heating time can be, for example, 10 minutes or more and 24 hours or less, or 30 minutes or more and 10 hours or less. The endpoint of the heating time can be appropriately set while confirming that the total amine value and / or hydroxyl value of the decomposition product has been sufficiently reduced.

[0050] The method for producing regenerated polyols involves stirring a mixture of the decomposed product and a polycarboxylic acid and / or its anhydride during the heating process described above.

[0051] Adding a polycarboxylic acid and / or its anhydride and heating it results in a dehydration condensation; therefore, the method for producing regenerated polyols can supply a dry gas during the heating process described above. For example, it is suggested that the decomposition product be added to a container with the polycarboxylic acid and / or its anhydride and heated, while a dry gas is supplied to the container from an external gas supply source. Dry nitrogen, for example, is suitable as the dry gas.

[0052] Typically, when amine compounds and carboxylic acids are mixed at room temperature (e.g., 25°C), carboxylates are formed. Since this reaction is reversible, the salt may dissociate in the regenerated polyol. On the other hand, if an amine compound is mixed with a polycarboxylic acid and / or its anhydride and heated above 150°C, the amino and carboxyl groups undergo dehydration condensation to form an amide bond. Furthermore, in the regenerated polyol, it can exist as an amide compound that is more difficult to dissociate than a carboxylate. Further, if a low-molecular-weight compound with hydroxyl groups is mixed with a polycarboxylic acid and / or its anhydride and heated above 150°C, the hydroxyl and carboxyl groups undergo dehydration condensation to form an ester bond. Furthermore, in the regenerated polyol, it can exist as an ester compound. The technology disclosed herein improves the quality of regenerated polyols by converting at least a portion of the amine compound into an amide compound and at least a portion of the low-molecular-weight compound with hydroxyl groups into an ester compound.

[0053] Furthermore, the technology disclosed herein utilizes polycarboxylic acids and / or their anhydrides to ensure that reactive groups remain in the reaction products. Therefore, when recycled polyols are used as regeneration feedstocks, bleed of the reaction products can be suppressed. Additionally, when recycled polyols are used as regeneration feedstocks, the degradation of the physical properties of the regenerated resin can be suppressed.

[0054] In the following description, the product obtained by adding a specified amount of a polycarboxylic acid and / or its anhydride to the decomposition product and heating it to above 150°C is also referred to as an acid-added product. Furthermore, the technology disclosed herein should not be limited to the above-described reaction mechanism.

[0055] The acid additive is preferably a single-phase state in which the liquid phase containing the regenerated polyol is not clearly separated. That is, it is preferably a homogeneous state in which the liquid phase containing the regenerated polyol is homogeneous. The acid additive may contain solid components. When the total amount of the acid additive is set to 100% by mass, the amount of solid components in the acid additive is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. The amount of solid components in the acid additive can be 0% by mass. The amount of solid components in the acid additive can be calculated, for example, by filtering the acid additive under normal pressure through a 40-mesh stainless steel mesh for 24 hours, measuring the weight of the residue, and calculating the weight percentage relative to the weight before filtration.

[0056] The method for manufacturing recycled polyols can directly obtain recycled polyols from acid-added treatment products. That is, the method can produce recycled polyols containing amide compounds and / or ester compounds. In this way, after reaction with polycarboxylic acids and / or their anhydrides, no special removal processes are required, and recycled polyurethane raw materials can be obtained easily and without generating waste.

[0057] Alternatively, the recycled polyol can also be obtained by removing solid components from the acid-added treatment. There are no particular limitations on the method for removing the solid components. For example, the solid components can be removed by filtering the acid-added treatment. Furthermore, solid components present as precipitates can be removed, for example, by removing only the liquid phase containing the recycled polyol from the container. The recycled polyol obtained after removing the solid components can be used directly as a regeneration feedstock. The uses of the recycled polyol will be explained later.

[0058] 2. Regenerated polyols Regenerated polyols are obtained by adding organic carboxylic acids having two or more carboxyl groups and / or their anhydrides to the decomposed product obtained by treating polyurethane resin with a decomposition agent.

[0059] In the description of the regenerated polyol, the polyurethane resin, decomposing agent, decomposition treatment product, organic carboxylic acid with two or more carboxyl groups and / or its anhydrides (polycarboxylic acid and / or its anhydrides) can be referred to the description of "(1) polyurethane resin", "(2) decomposing agent", "(5) decomposition treatment product" and "(6) organic carboxylic acid with two or more carboxyl groups and / or its anhydrides (polycarboxylic acid and / or its anhydrides)" in the column "1. Decomposition treatment method of polyurethane resin", so its description is omitted.

[0060] Regenerated polyols can be readily obtained, for example, by the above-described method for manufacturing regenerated polyols. In the description of regenerated polyols, please refer to the descriptions of “(3) decomposition catalyst”, “(7) ratio of the molar amount of carboxyl groups to the total molar amount of amino groups and hydroxyl groups of the decomposition agent in the decomposition product”, and “(8) heating” in the column “1. Decomposition treatment method of polyurethane resin”.

[0061] The amine value of the recycled polyol is 55 mg KOH / g or less, preferably 45 mg KOH / g or less, more preferably 35 mg KOH / g or less, and even more preferably 25 mg KOH / g or less. There is no particular limitation on the lower limit of the amine value of the recycled polyol. The amine value of the recycled polyol is typically 15 mg KOH / g or more.

[0062] In addition, the amine value of regenerated polyol refers to the total amine value of the regenerated polyol obtained by removing precipitates, as determined by JIS K 1557.

[0063] There are no particular restrictions on the hydroxyl value of regenerated polyols. For example, the hydroxyl value of regenerated polyols should be above 85 mg KOH / g and below 150 mg KOH / g.

[0064] In addition, the hydroxyl value of regenerated polyols refers to the hydroxyl value of the regenerated polyols obtained by removing precipitates, as determined by JIS K 1557.

[0065] The pH of the recycled polyol is 5.5 or higher, preferably 6.0 or higher, more preferably 6.5 or higher, and even more preferably 7.0 or higher. There is no particular upper limit to the pH of the recycled polyol. The pH of the recycled polyol is typically below 9.0.

[0066] In addition, the pH of the regenerated polyol refers to the pH of the regenerated polyol obtained by removing precipitates, as determined by JIS K 1557.

[0067] If the amine value and pH of the regenerated polyol are within the aforementioned range, the regenerated polyol can be effectively utilized as a regenerated raw material. In the technology disclosed herein, since the reaction products of polycarboxylic acids and / or their anhydrides with amine compounds and the reaction products of polycarboxylic acids and / or their anhydrides with low molecular weight compounds containing hydroxyl groups are difficult to dissociate, the amine value of the regenerated polyol can be sufficiently reduced. Furthermore, it is presumed that the pH of the regenerated polyol is unlikely to increase.

[0068] Regenerated polyols may contain amide compounds and / or ester compounds, with the presence of both amide and ester compounds being preferred. The aforementioned amide compounds, for example, have structures derived from the added polycarboxylic acids and / or their anhydrides. The aforementioned ester compounds, for example, have structures derived from the added polycarboxylic acids and / or their anhydrides.

[0069] There are no particular limitations on the uses of recycled polyols. For example, recycled polyols can be used as recycled raw materials for obtaining recycled polyurethane resins.

[0070] Recycled polyurethane resin can be manufactured, for example, by mixing isocyanate into recycled polyol. Recycled polyurethane resin can be manufactured using known methods. The foaming method for obtaining polyurethane foam can be either block foaming or molding foaming. Block foaming involves discharging the mixed recycled polyol and isocyanate onto a conveyor belt and foaming it at atmospheric pressure and room temperature. Molding foaming, on the other hand, involves filling the mixed recycled polyol and isocyanate into a mold (molding mold) and foaming it within the mold.

[0071] Example 1. Manufacturing of polyurethane resin A polyurethane foam composition (liquid A and liquid B) was prepared in the proportions shown in Table 1, and polyurethane foam was manufactured as the polyurethane resin to be decomposed by block foaming. The density of the obtained polyurethane foam was determined according to JIS K 7222:2005. The measured densities are also recorded in Table 1.

[0072] The details of each raw material are as follows.

[0073] Polyol: Polyether polyol, number average molecular weight 3000, functional groups 3, hydroxyl value 56.1 mgKOH / g, trade name: SANNIX GP-3050NS, manufactured by Sanyo Chemical Industry Co., Ltd. Amine catalyst: Trade name: DABCO 33LSI, manufactured by EVONIK Co., Ltd. Foaming agent: Silicone foaming agent, trade name: L-595, manufactured by Momentive Co., Ltd. Tin catalyst: Stannous octoate, trade name: MRH-110, manufactured by Jōhoku Chemical Industry Co., Ltd. Foaming agent: water Isocyanate: Toluene diisocyanate, trade name: Coronate T-80, manufactured by Tosoh Co., Ltd., NCO%: 48.2% [Table 1]

[0074] 2. Decomposition treatment of polyurethane resin In a 1L separable flask, 100g of the polyurethane resin to be decomposed was mixed with a decomposing agent (15g diethylene glycol and 5g glycerol, totaling 20g), a decomposing catalyst (0.5g), and a solvent (50g). The mixture was heated at 200℃ for 6 hours with stirring to obtain the decomposed product. Details of the decomposing agent, catalyst, and solvent are as follows. The decomposed product was in a single-phase state, not separated into a polyol phase and an amine phase; that is, it was in a homogeneous liquid phase.

[0075] Decomposing agent: A compound containing hydroxyl groups, a mixture of diethylene glycol and glycerol in a 3:1 ratio. Decomposition catalyst: 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) Solvent: Polyether polyol, number average molecular weight 3000, functional groups 3, hydroxyl value 56.1 mgKOH / g, trade name: SANNIX GP-3050NS, manufactured by Sanyo Chemical Industry Co., Ltd. The total amine value and hydroxyl value of the obtained decomposition products were determined according to JIS K 1557. The results are as follows.

[0076] The total amine value of the decomposition product was 76 mg KOH / g. Hydroxyl value of the decomposition product = 278 mg KOH / g 3. Acid addition treatment of decomposition products The decomposed material was processed to obtain the samples of the examples and comparative examples.

[0077] In a 1L separable flask, the polycarboxylic acids or anhydrides listed in Tables 2 and 3 were added to the decomposition product. The amount of polycarboxylic acids or anhydrides added was adjusted so that the ratio of the molar amount of carboxyl groups to the total molar amount of amino groups and hydroxyl groups from the decomposition agent in the decomposition product was the value in the "Molar ratio of carboxyl groups (relative to amino groups + hydroxyl groups from the decomposition agent)" column of Table 1.

[0078] The molar amount of amino groups in the decomposition product is calculated based on the total amine value of the decomposition product as described above.

[0079] The molar amount of carboxyl groups is calculated by multiplying the molar amount of the added polycarboxylic acid by the number of carboxyl groups, or by multiplying the molar amount of the added acid anhydride by twice the number of anhydride groups. For example, 1 mole of succinic anhydride has a molar amount of 2 carboxyl groups. For example, 1 mole of succinic acid has a molar amount of 2 carboxyl groups.

[0080] The molar amount of hydroxyl groups in the decomposition agent is calculated by multiplying the molar amount of the decomposition agent added during the decomposition process by the number of hydroxyl groups. For example, 1 mole of diethylene glycol has a molar amount of 2 hydroxyl groups. For example, 1 mole of glycerol has a molar amount of 3 hydroxyl groups.

[0081] The aforementioned polycarboxylic acids or anhydrides were added to the decomposition products, and the mixture was heated to the reaction temperatures described in Tables 2 and 3. The heating time was set to 3 hours. Since dehydration condensation occurs after the addition of the polycarboxylic acids or anhydrides, the reaction was carried out while dry nitrogen was introduced. The resulting samples were in a single-phase state. Solid components were confirmed in some samples.

[0082] The liquid phase of each sample after the reaction was filtered through a 40-mesh stainless steel mesh under normal pressure to collect the regenerated polyols.

[0083] [Table 2]

[0084] [Table 3]

[0085] 4. Evaluation Methods The pH of the regenerated polyol was determined according to JIS K 1557 and evaluated using the following benchmarks.

[0086] <pH Evaluation Criteria> A: pH 7 or higher.

[0087] B: pH 6 or higher and less than 7.

[0088] C: less than pH 6.

[0089] The total amine value of the regenerated polyols was determined according to JIS K 1557 and evaluated using the following criteria.

[0090] <Evaluation Criteria for Total Amine Value> A: Less than 30 mg KOH / g.

[0091] B: 30 mg KOH / g or higher but less than 50 mg KOH / g.

[0092] C: 50 mg KOH / g or higher.

[0093] The hydroxyl value of the regenerated polyol was determined according to JIS K 1557.

[0094] Measure the weight of the residue collected during the regeneration of the polyols and calculate its weight percentage relative to the weight before filtration. Evaluate the residue weight using the following criteria.

[0095] <Evaluation Criteria for Filter Residue> A: The residue weight is less than 3%.

[0096] C: The residue weight is greater than 3%.

[0097] The obtained regenerated polyols were comprehensively evaluated based on the following criteria.

[0098] A: The evaluation of "pH" is "A", the evaluation of "total amine value" is also "A", and the evaluation of "filtration residue" is also "A".

[0099] B: “B” appears in the evaluation of “pH” and / or “total amine value” and “filter residue”, but “C” does not appear in the evaluation of “pH”, “total amine value” and “filter residue”.

[0100] C: Any one of the following evaluations: pH, total amine value, and filter residue.

[0101] 5. Results The evaluation results are recorded in Tables 2 and 3.

[0102] Examples 1 through 9 satisfy the following conditions (a) through (c). Comparative Examples 1 and 2 do not satisfy condition (a). Comparative Examples 3 through 5 do not satisfy condition (b).

[0103] Condition (a): An organic carboxylic acid having two or more carboxyl groups and / or its anhydride is added to the decomposition product obtained by treating polyurethane resin with a decomposition agent, such that the molar amount of carboxyl groups to the total molar amount of amino groups and hydroxyl groups of the decomposition agent in the decomposition product is 0.5 or more and 1.0 or less.

[0104] Condition (b): Heating to above 150°C.

[0105] Condition (c): Obtain the regenerated polyol.

[0106] The overall assessment of Examples 1 to 9 is "A" or "B". The overall assessment of Comparative Examples 1 to 5 is "C". Compared with Comparative Examples 1 to 5, Examples 1 to 9, which meet conditions (a) to (c), can yield high-quality regenerated polyols.

[0107] Examples 1 through 9 satisfy the following conditions (d) through (f). Comparative Examples 1 and 3 through 5 do not satisfy the following condition (f). Comparative Example 2 does not satisfy the following condition (e).

[0108] Condition (d): Regenerated polyol obtained by adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride to the decomposed product obtained by treating polyurethane resin with a decomposition agent.

[0109] Condition (e): The amine value of the regenerated polyol is below 55 mg KOH / g.

[0110] Condition (f): The pH of the regenerated polyol is above 5.5.

[0111] The overall assessment of Examples 1 to 9 is "A" or "B". The overall assessment of Comparative Examples 1 to 5 is "C". Compared with Comparative Examples 1 to 5, Examples 1 to 9, which meet conditions (d) to (f), can yield high-quality regenerated polyols.

[0112] 6. Effects of the Implementation Example According to this embodiment, a technique for obtaining high-quality recycled polyols can be provided.

[0113] This disclosure is not limited to the embodiments described in the detailed description above, and various modifications or alterations can be made within the scope of this disclosure.

Claims

1. A method for manufacturing recycled polyols, wherein, An organic carboxylic acid having two or more carboxyl groups and / or its anhydride is added to a decomposition product obtained by treating polyurethane resin with a decomposition agent, such that the molar ratio of the carboxyl groups to the total molar ratio of the amino groups in the decomposition product and the hydroxyl groups of the decomposition agent is 0.5 or more and 1.0 or less. Heating to above 150°C yields regenerated polyols.

2. The method for manufacturing recycled polyols according to claim 1, wherein, The decomposed product is obtained through alcoholysis.

3. A recycled polyol, wherein, It is obtained by adding organic carboxylic acids having two or more carboxyl groups and / or their anhydrides to the decomposition product obtained by treating polyurethane resin with a decomposition agent. The amine value of the regenerated polyol is below 55 mg KOH / g. The pH of the regenerated polyol is above 5.

5.

4. The recycled polyol according to claim 3, wherein, The decomposed product is obtained through alcoholysis.

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