Polyurethane resin decomposition agent, method for producing polyurethane decomposition products, polyurethane decomposition products, and polyurethane foam

Abstract

This invention provides a novel technology for decomposing polyurethane resins manufactured using polyester polyols. [Solution] The polyurethane resin decomposition agent is a polyurethane resin decomposition agent manufactured using a polyester polyol, and contains 0.2 parts by mass to 3 parts by mass of a tertiary amine compound per 100 parts by mass of a secondary hydroxyl group-containing polyol with a number average molecular weight of 100 or more.

Description

Technical Field

[0001] The present disclosure relates to a decomposing agent for polyurethane resin, a method for producing a polyurethane decomposition product, a polyurethane decomposition product, and a polyurethane foam.

Background Art

[0002] Patent Document 1 discloses a glycol decomposition method as one of the chemical recycling technologies for polyurethane. The technology of Patent Document 1 uses an aliphatic diol having 2 to 6 carbon atoms as a decomposing agent for urethane foam.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a technology for decomposing a polyurethane resin produced using a polyester polyol is required. When ethylene glycol is used as a decomposing agent for a polyurethane resin produced using a polyester polyol, there is a problem that the ester bond in the polyurethane resin is also decomposed by an ester exchange reaction.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a novel technology for decomposing a polyurethane resin produced using a polyester polyol. The present disclosure can be realized in the following forms.

Means for Solving the Problems

[0006] A decomposing agent for a polyurethane resin produced using a polyester polyol, A decomposition agent for polyurethane resins, comprising 0.2 to 3 parts by mass of a tertiary amine compound per 100 parts by mass of a secondary hydroxyl group-containing polyol with a number average molecular weight of 100 or more. [Effects of the Invention]

[0007] This disclosure provides a novel technology for decomposing polyurethane resins manufactured using polyester polyols. [Brief explanation of the drawing]

[0008] [Figure 1] These are the chromatograms for Sample 1-Sample 3. [Figure 2] These are chromatograms of polyester polyol A alone, sample A, and sample E. [Figure 3] These are chromatograms of polyester polyol A alone, PEG400 alone, sample C, and sample F. [Figure 4] These are chromatograms of polyester polyol A alone, GP400 alone, sample D, and sample G. [Figure 5] These are chromatograms of polyester polyol A alone and sample B. [Figure 6] These are chromatograms of polyester polyol A alone, PP400 alone, and sample H. [Modes for carrying out the invention]

[0009] Herein lies a preferred example of this disclosure. [1] A decomposing agent for polyurethane resins manufactured using polyester polyols, A decomposition agent for polyurethane resins, comprising 0.2 to 3 parts by mass of a tertiary amine compound per 100 parts by mass of a secondary hydroxyl group-containing polyol with a number average molecular weight of 100 or more. [2] The decomposing agent for polyurethane resin according to [1], wherein the secondary hydroxyl group-containing polyol has a number average molecular weight of 100 or more and 2800 or less. [3] The secondary hydroxyl group-containing polyol is polypropylene glycol, a decomposing agent for polyurethane resins according to [1] or [2]. [4] A method for producing a polyurethane decomposition product, comprising decomposing the polyurethane resin with the polyurethane resin decomposition agent described in [1] or [2]. [5] A polyurethane decomposition product obtained by decomposing the polyurethane resin with the polyurethane resin decomposition agent described in [1] or [2]. [6] A polyurethane foam obtained from a composition comprising some or all of the polyurethane decomposition products described in [5] and an isocyanate.

[0010] The disclosure is described in detail below. In this specification, when a numerical range is described using "-", it includes both the lower and upper limits unless otherwise specified. For example, the description "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, in this specification, the upper and lower limits of each numerical range can be combined in any way.

[0011] 1. Polyurethane resin decomposing agent The polyurethane resin decomposition agent is a decomposition agent for polyurethane resins manufactured using polyester polyols, and contains 0.2 to 3 parts by mass of a tertiary amine compound per 100 parts by mass of a secondary hydroxyl group-containing polyol with a number average molecular weight of 100 or more. Hereinafter, polyurethane resins manufactured using polyester polyols will also be simply referred to as ester-based polyurethane resins.

[0012] (1) Ester-based polyurethane resin Ester-based polyurethane resins are manufactured using polyester polyols. The polyester polyol is preferably one or more selected from polyester polyols obtained by condensation of one or more compounds having at least two hydroxyl groups with one or more compounds having at least two carboxyl groups, and ring-opening polymers of cyclic esters. The polyester polyol may consist of only one type or two or more types.

[0013] Compounds having at least two hydroxyl groups are not particularly limited. Examples of compounds having at least two hydroxyl groups include compounds selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,3- and 1,4-butanediol, tetramethylene glycol, neopentyl glycol, methylpentanediol, butylethylpropanediol, hexamethylene glycol, decamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol. There may be only one compound or two or more compounds having at least two hydroxyl groups. The compound having at least two hydroxyl groups is preferably a combination of a diol and a polyhydric alcohol, and more preferably a combination of diethylene glycol and trimethylolpropane.

[0014] Compounds having at least two carboxyl groups are not particularly limited. Examples of compounds having at least two carboxyl groups include compounds selected from the group consisting of malonic acid, maleic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, pimelic acid, azelaic acid, sebacic acid, oxalic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and hemeltic acid. There may be only one compound or two or more compounds having at least two carboxyl groups. The compound having at least two carboxyl groups is preferably an aliphatic dibasic acid, and more preferably an adipic acid.

[0015] The above cyclic ester is, for example, a lactone which is a cyclic ester having 2 to 15 carbon atoms, preferably 4 to 10 carbon atoms. Specific examples of the cyclic ester include ε-caprolactone, methylvalerolactone, γ-butyrolactone, δ-valerolactone, β-propiolactone, α-methyl-γ-butyrolactone, coumarin, macrolide lactones (for example, erythromycin, tacrolimus, etc.), γ-palmitolactone, α-angelicalactone, γ-decalactone and the like.

[0016] As the raw material polyol of the ester-based polyurethane resin, a polyol other than the polyester polyol may be included. Examples of the polyol other than the polyester polyol include polyether polyol, polyether ester polyol, polycarbonate diol, a polyol having a carbon-carbon bond-based main chain, and the like. In addition, each of the various polyols exemplified as the polyol other than the polyester polyol may be only one kind or two or more kinds.

[0017] When the total amount of the raw material polyol of the ester-based polyurethane resin is 100 parts by mass, the content of the polyester polyol is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, still more preferably 10 parts by mass or more, and may be 20 parts by mass or more, 40 parts by mass or more, 60 parts by mass or more. The upper limit value of the content of the polyester polyol is not particularly limited, and may be, for example, 100 parts by mass or less, 80 parts by mass or less, 60 parts by mass or less. The content of the polyester polyol can be within a range obtained by appropriately combining the above lower limit value and upper limit value.

[0018] Ester-based polyurethane resins are not particularly limited as long as they are manufactured using polyester polyols. An example of an ester-based polyurethane resin is polyurethane foam. The polyurethane foam may be flexible polyurethane foam, semi-rigid polyurethane foam, or rigid polyurethane foam. The polyurethane foam may have an open-cell structure or a closed-cell structure. The polyurethane foam may be crushed to a predetermined size, or cut to a predetermined size. The polyurethane foam may be, for example, scraps discharged during the manufacturing process of polyurethane foam, or used polyurethane foam that is scheduled for disposal.

[0019] (2) Secondary hydroxyl group-containing polyols with a number average molecular weight of 100 or more The polyurethane resin decomposition agent contains a secondary hydroxyl group-containing polyol (hereinafter also referred to as polyol A) with a number average molecular weight of 100 or more. The polyurethane resin decomposition agent of this disclosure suppresses the decomposition of ester bonds in ester-based polyurethane resins, thereby obtaining high-quality polyurethane decomposition products. While the reason is not entirely clear, it is presumed that secondary hydroxyl groups are less likely to undergo transesterification reactions with ester bonds compared to primary hydroxyl groups. This disclosure is not intended to be limited to this presumed reason.

[0020] Polyol A is preferably, for example, polyalkylene glycol. Polyalkylene glycol is, for example, one or more selected from the group consisting of polypropylene glycol, polybutylene glycol, ethylene oxide adducts at the ends of polypropylene glycol, and ethylene oxide adducts at the ends of polybutylene glycol. Polyalkylene polyols can be produced by polymerizing alkylene glycol using water, alcohol, etc. as an initiator. Among these, polypropylene glycol is more preferred for polyol A. Polypropylene glycol can be produced by polymerizing propylene oxide. Polyol A may be used alone, or two or more may be used in combination.

[0021] The number-average molecular weight of polyol A is 100 or more, preferably 300 or more, more preferably 400 or more, and may also be 600 or more, 800 or more, 1200 or more, or 1600 or more, from the viewpoint of sufficiently suppressing the transesterification reaction. The number-average molecular weight of polyol A is usually 5000 or less, preferably 3500 or less, and from the viewpoint of the quality of the polyurethane decomposition product, preferably 2800 or less, more preferably 2300 or less, and even more preferably 2100 or less. The quality of the polyurethane decomposition product refers to, for example, the quality related to foaming when used in the manufacture of polyurethane foam. The number-average molecular weight of polyol A can be set to a range that appropriately combines the above lower and upper limits. The number-average molecular weight of polyol A can be measured, for example, by gel permeation column chromatography (GPC).

[0022] The number of functional groups in polyol A is not particularly limited. Preferably, the number of functional groups in polyol A is 2 to 10, more preferably 2 to 8, even more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 or 3. The number of secondary hydroxyl groups in polyol A is not particularly limited. For example, the number of secondary hydroxyl groups in polyol A is preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 6, and usually 2 to 4. Polyol A may have primary hydroxyl groups. From the viewpoint of suppressing transesterification reactions, the number of primary hydroxyl groups in polyol A is preferably 2 or less, more preferably 1 or less, and most preferably 0. Polyol A may have functional groups other than secondary and primary hydroxyl groups, but it is preferable that it does not have functional groups other than secondary and primary hydroxyl groups.

[0023] (3) Tertiary amine compounds The decomposition agent for polyurethane resin contains a tertiary amine compound. Primary amine compounds and / or secondary amine compounds are susceptible to being consumed and deactivated by the decomposition reaction of polyurethane resin. On the other hand, tertiary amine compounds are preferable because they are less likely to be deactivated by the decomposition reaction of polyurethane resin. Furthermore, for example, when polyurethane decomposition products are used in the production of polyurethane foam, tertiary amine compounds can function as catalysts for the formation of polyurethane resin. Therefore, when the decomposition catalyst is a tertiary amine compound, it is also preferable from the viewpoint of utilizing the polyurethane decomposition products.

[0024] The tertiary amine compounds of this disclosure have at least one tertiary amino group as a functional group other than a hydrocarbon group within the molecule. Preferably, the tertiary amine compounds do not have a hydroxyl group within the molecule. The number of tertiary amino groups in a tertiary amine compound is not particularly limited. Preferably, the number of tertiary amino groups is between 1 and 4, and more preferably between 1 and 3. The molecular weight of the tertiary amine compound is not particularly limited. Preferably, the molecular weight of the tertiary amine compound is 600 or less, more preferably 400 or less, and even more preferably 200 or less. The lower limit is not particularly limited, but for example, it is 60 or more.

[0025] The tertiary amine compound is preferably one used in the production of polyurethane resins, for example. If it is a catalyst used in the urethane reaction, it can efficiently decompose the urethane bonds, and even if the urethane decomposition product is used in the production of polyurethane foam, it will have little adverse effect on the foaming reaction.

[0026] Tertiary amine compounds include, for example, diazabicycloundecene, 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, 4-dimethylaminopyridine, N,N'-dimethylpiperazine, N-methyl-N'-( The tertiary amine compound is one or more selected from the group consisting of 2-dimethylamino)ethylpiperazine, N-methylmorpholine, N-(N',N'-dimethylaminoethyl)morpholine, 1,2-dimethylimidazole, hexamethylenetetramine, dimethylaminoethanol, dimethylaminoethoxyethanol, N,N,N'-trimethylaminoethylethanolamine, N-methyl-N'-(2-hydroxyethyl)-piperazine, N-(2-hydroxyethyl)morpholine, bis(2-dimethylaminoethyl) ether, and ethylene glycol bis(3-dimethyl)-aminopropyl ether. The tertiary amine compound may be used alone or in combination of two or more.

[0027] Tertiary amine compounds may be used in combination with decomposition catalysts other than tertiary amine compounds. Examples of decomposition catalysts other than tertiary amine compounds include one or more obtained from the group consisting of stanus octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin thiocarboxylate, dibutyltin maleate, dioctyltin mercaptide, dioctyltin thiocarboxylate, lead octenoate, potassium acetate, and potassium octoate. However, from the viewpoint of suppressing hydrolysis, it is desirable that the decomposition agent for polyurethane resins does not contain inorganic bases such as KOH or NaOH. This is because inorganic bases are highly likely to cause cleavage of ester bonds due to hydrolysis. For example, NaOH has a pKa of 13, KOH has a pKa of 15.7, and diazabicycloundecene (DBU) has a pKa of 11.5. Since NaOH and KOH are more strongly alkaline than diazabicycloundecene (DBU), hydrolysis is considered more likely to occur with NaOH or KOH at the same concentration.

[0028] The content of the tertiary amine compound is 0.2 parts by mass or more per 100 parts by mass of the above polyol A, preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, and may also be 0.6 parts by mass or more, or 0.8 parts by mass or more, from the viewpoint of promoting the decomposition of urethane bonds. The content of the above tertiary amine compound is 3 parts by mass or less, preferably 2.5 parts by mass or less, and more preferably 2.2 parts by mass or less, from the viewpoint of suppressing the decomposition of ester bonds. The content of the above tertiary amine compound can be set within a range that appropriately combines the above lower and upper limits.

[0029] (4) Other ingredients The polyurethane resin decomposition agent may further contain components other than polyol A, a tertiary amine compound, and a decomposition catalyst (also referred to as other components). For example, the polyurethane resin decomposition agent may further contain a polyol having a number average molecular weight greater than polyol A (for example, a number average molecular weight greater than 2800).

[0030] 2. Method for producing polyurethane decomposition products A method for producing polyurethane decomposition products involves, for example, decomposing the polyurethane resin using the polyurethane resin decomposition agent described above.

[0031] The amount of polyurethane resin decomposition agent added is not particularly limited. The amount of polyurethane resin decomposition agent added is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 25 parts by mass or more and 150 parts by mass or less, even more preferably 40 parts by mass or more and 120 parts by mass or less, and particularly preferably 50 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of ester-based polyurethane resin.

[0032] The decomposition conditions for polyurethane resin are not particularly limited. From the viewpoint of improving the decomposition rate, a method for producing polyurethane decomposition products is to heat the polyurethane resin together with the polyurethane resin decomposition agent described above. When heating the polyurethane resin together with the polyurethane resin decomposition agent described above, it is preferable to stir the mixture of ester-based polyurethane resin and polyurethane resin decomposition agent.

[0033] From the viewpoint of improving the decomposition rate, the heating temperature is preferably 100°C or higher, more preferably 125°C or higher, and even more preferably 150°C or higher. From the viewpoint of suppressing the decomposition of ester bonds, the heating temperature is 210°C or lower, more preferably 190°C or lower, and even more preferably 170°C or lower. From these viewpoints, the heating temperature is preferably 100°C to 210°C, more preferably 125°C to 190°C, and even more preferably 150°C to 180°C.

[0034] The decomposition treatment time may be, for example, 10 minutes to 24 hours, or 30 minutes to 10 hours. The end point of the decomposition treatment time may be set appropriately while checking the progress of the decomposition of the polyurethane resin, depending on the size of the polyurethane resin, whether or not it is stirred, etc. Also, for example, when decomposing the polyurethane resin at room temperature (e.g., 25°C) or below 80°C, the decomposition treatment time may be set to be longer than 24 hours.

[0035] 3. Polyurethane decomposition products Polyurethane decomposition products can be obtained, for example, by decomposing polyurethane resin with the above-mentioned polyurethane resin decomposition agent.

[0036] Polyurethane decomposition products include, for example, polyols derived from the polyol raw material of the polyurethane resin, and amine components derived from the isocyanate raw material. In addition, polyurethane decomposition products may also contain flame retardants, catalysts, and other additives that were contained in the polyurethane resin.

[0037] The state of the polyurethane decomposition product is not particularly limited. Preferably, the polyurethane decomposition product is obtained as a single-phase liquid. In this disclosure, the "single-phase" liquid refers to a liquid substance whose "mismatch" evaluation in the examples described later is "A". The single-phase liquid is thought to contain, for example, a polyol derived from the raw material polyol and an amine component derived from the raw material isocyanate in a mismatched state. The single-phase liquid may also contain solid components. The solid components may include, for example, flame retardants such as phosphorus-based flame retardants and halogen-based flame retardants, pigments, hygroscopic agents, and solid components containing polymer polyols.

[0038] Polyurethane decomposition products inherently have poor compatibility between their components and are prone to phase separation. For example, when ethylene glycol, glycerin, and diethylene glycol are used as decomposition agents for polyurethane resin, the polyurethane decomposition products tend to be in a phase-separated state. If polyurethane decomposition products can be obtained as a single-phase liquid rather than in a phase-separated state, they can be used directly in the production of polyurethane foam, for example. Furthermore, obtaining polyurethane decomposition products as a single-phase liquid eliminates the need for the separation of unnecessary phases and contributes to reducing the amount of waste compared to discarding the unnecessary phases.

[0039] Furthermore, if polyurethane decomposition products can be obtained as a single liquid phase, the generation of solids themselves will be less likely. The reason for this is not entirely clear, but it is thought that the following is the case: When polyurethane decomposition products are in a phase-separated state, the polymer polyol-containing solids and flame retardants, etc., are localized in one of the phases, leading to localized high concentrations and making it easier for solids to form. On the other hand, if polyurethane decomposition products can be obtained as a single liquid phase, the polymer polyol-containing solids and flame retardants, etc., can be dispersed throughout the entire system, making it less likely for solids to form. This disclosure is not intended to be limited to this speculative reason.

[0040] The uses of polyurethane decomposition products are not particularly limited. Polyurethane decomposition products are suitable as raw materials for polyurethane foam. For example, if the polyurethane decomposition product is in a single liquid phase, it can be easily mixed directly into a polyurethane foam composition and reused.

[0041] 4. Polyurethane foam Polyurethane foam can be obtained from a composition comprising, for example, some or all of polyurethane decomposition products and an isocyanate. Using all of the polyurethane decomposition products means using the polyurethane decomposition products as they are. Using some of the polyurethane decomposition products means, for example, the portion of the polyurethane decomposition product from which solid matter has been removed, or, in the case where the polyurethane decomposition product is separated into two phases, the phase containing more polyol (the polyol phase). In the description of polyurethane foam, the explanation for "polyurethane decomposition products" in section "3. Polyurethane Decomposition Products" will be applied as is, and the description will be omitted.

[0042] Polyurethane foam can be manufactured by known methods. Methods for obtaining polyurethane foam include slab foaming and mold foaming, and either method may be used. Slab foaming involves extruding a mixed polyurethane foam composition onto a belt conveyor and foaming it under atmospheric pressure. Mold foaming, on the other hand, involves filling a mold with a mixed polyurethane foam composition and foaming it within the mold. [Examples]

[0043] 1. Preliminary Experiment 1 To investigate the effect of polyol species on transesterification reactions in polyester polyols, the following preliminary experiments were conducted. Sample 1 consisted of 100 parts by mass of polyester polyol A to which only 1 part by mass of diazabicycloundecene was added. Sample 2 consisted of 100 parts by mass of polyester polyol 2 to which 100 parts by mass of polypropylene glycol and 1 part by mass of diazabicycloundecene were added. Sample 3 consisted of 100 parts by mass of polyester polyol 2 to which 100 parts by mass of polyethylene glycol and 1 part by mass of diazabicycloundecene were added.

[0044] Details of each ingredient are as follows: • Polyester polyol A: A polyester polyol obtained by condensation of diethylene glycol and adipic acid, with a number-average molecular weight of 2400 and 2.6 functional groups. • Polypropylene glycol: Number-average molecular weight 400, number of functional groups 2 • Polyethylene glycol: Number-average molecular weight 400, number of functional groups 2 The above polypropylene glycol corresponds to a "secondary hydroxyl group-containing polyol with a number-average molecular weight of 100 or more." Diazabicycloundecene corresponds to a "tertiary amine compound." The above polyethylene glycol has the same number-average molecular weight as the above polypropylene glycol and is a polyol that does not have the same number of secondary hydroxyl groups as the above polypropylene glycol.

[0045] Samples 1-3 were heated at 200±10°C for 1 hour, and the treated products after heating were analyzed by GPC. The results are shown in Figure 1. In the chromatogram in Figure 1, it can be seen that longer elution times correspond to smaller molecules. In this chromatogram, it can be seen that the fewer low molecular weight components there are, the more suppressed the decomposition of polyester polyols is, and the higher the quality of the polyurethane decomposition product obtained.

[0046] As shown in Figure 1, in Sample 1, which was not treated with a polyol, a maximum peak was detected at an elution time of 12-13 / min. In Sample 2, which was treated with polypropylene glycol, a peak was detected at an elution time of 12-13 / min, although a larger amount of low molecular weight components was detected compared to Sample 1. In Sample 3, which was treated with polyethylene glycol, a larger amount of low molecular weight components was detected compared to Sample 2, and no peak was detected at an elution time of 12-13 / min. This is likely because in Sample 3, the transesterification reaction occurred more readily than in Sample 2, and the polyester polyol was decomposed into components with lower molecular weight. From these results, it can be inferred that polyols containing secondary hydroxyl groups are less likely to undergo transesterification reactions than polyols without secondary hydroxyl groups that have a similar number-average molecular weight and the same number of functional groups.

[0047] 2. Preliminary Experiment 2 To investigate the influence of polyol species and decomposition catalyst species on the transesterification reaction in polyester polyols, the following preliminary experiments were conducted. For samples A-H, the decomposition agent was added to 100 parts by mass of polyester polyol A in the mass ratios shown in Table 1.

[0048] Details of each ingredient are as follows: • Polyester polyol A: A polyester polyol obtained by condensation of diethylene glycol and adipic acid, with a number-average molecular weight of 2400 and 2.6 functional groups. Ethylene glycol (EG): Molecular weight 62, number of functional groups 2 • Polyethylene glycol (PEG400): Number average molecular weight 400, number of functional groups 2 • Polypropylene glycol (GP400): Number average molecular weight 400, number of functional groups 3 • Polypropylene glycol (PP400): Number average molecular weight 400, number of functional groups 2 • Tertiary amine compound: diazabicycloundecene (DBU) • Potassium hydroxide The above-mentioned polypropylene glycol corresponds to a "secondary hydroxyl group-containing polyol with a number average molecular weight of 100 or more."

[0049] [Table 1]

[0050] Samples A through H were placed in 200 mL round-bottom flasks and heated at 200°C for 1 hour using a mantle heater, then allowed to cool to room temperature. After cooling, GPC measurements were performed on each sample. The results are shown in Figures 2 through 6. The detection intensity of each chromatogram in each figure was set to an intensity that appropriately contained the peaks and to be on the same scale within the figure. In each chromatogram, it can be seen that longer elution times correspond to smaller molecules.

[0051] The first row of Figure 2 shows the chromatogram of polyester polyol A alone, the second row shows the chromatogram of sample A (with KOH added only), and the third row shows the chromatogram of sample E (with DBU added only). From these results, it was found that even when a mixture of polyester polyol and decomposition catalyst is heated, decomposition of the polyester polyol does not occur unless the polyol is added.

[0052] The first row of Figure 3 shows the chromatogram of polyester polyol A alone, the second row shows the chromatogram of PEG400 alone, the third row shows the chromatogram of sample C (PEG400 + KOH added), and the fourth row shows the chromatogram of sample F (PEG400 + DBU added). From these results, it was confirmed that in the presence of PEG400, which has primary hydroxyl groups, the peaks originating from the polyester polyol shift to the lower molecular weight side. The peak shape originating from PEG400 also changed, suggesting that they reacted with each other (transesterified).

[0053] The first row of Figure 4 shows the chromatogram of polyester polyol A alone, the second row shows the chromatogram of GP400 alone, the third row shows the chromatogram of sample D (GP400 + KOH added), and the fourth row shows the chromatogram of sample G (GP400 + DBU added). From sample G, it was confirmed that the change in the shape of the peak derived from the polyester polyol was not significant in the presence of GP400 and DBU. On the other hand, from sample D, it was confirmed that even in the presence of GP400, when the decomposition catalyst species was KOH, the change in the shape of the peak derived from the polyester polyol was considerably larger. This is thought to be due to the fact that inorganic bases are more likely to cause hydrolysis than tertiary amine compounds. Furthermore, from samples G and D, it was confirmed that in the presence of GP400 containing secondary hydroxyl groups, there was almost no change in the peak shape derived from GP400, regardless of the decomposition catalyst species. In addition, a comparison of sample G with sample F (PEG400 + DBU added) in Figure 3 suggests that GP400 undergoes a lower degree of transesterification than PEG400. From these results, it can be inferred that polyols containing secondary hydroxyl groups are less likely to undergo transesterification than polyols without secondary hydroxyl groups.

[0054] The first row of Figure 5 shows the chromatogram of polyester polyol A alone, and the second row shows the chromatogram of sample B (with EG + KOH added). From these results, it can be concluded that in the presence of EG, the high molecular weight fraction derived from the polyester polyol disappears, suggesting that short-chain primary diols like EG readily undergo transesterification reactions with polyester polyols.

[0055] The first row of Figure 6 shows the chromatogram of polyester polyol A alone, the second row shows the chromatogram of PP400 alone, and the third row shows the chromatogram of sample D (PP400 + DBU added). From these results, it was confirmed that polyester polyols are less susceptible to transesterification in the presence of PP400, which has secondary hydroxyl groups.

[0056] Based on the results of preliminary experiment 2, the following conclusions can be drawn: Polyols (glycols) with primary hydroxyl groups are highly likely to undergo transesterification reactions with polyester polyols, while polyols (glycols) with secondary hydroxyl groups are less likely to do so. This is presumed to be due to the difference in reactivity between primary and secondary hydroxyl groups. Furthermore, it is presumed that using a tertiary amine compound such as DBU as a decomposition catalyst, rather than an inorganic base such as KOH, would be more effective in suppressing the hydrolysis of polyester polyols.

[0057] 3. Manufacturing of polyurethane resin Polyurethane foam compositions (solutions A and B) were prepared in the proportions shown in Table 2, and a decomposable polyurethane resin (ester-based polyurethane resin) was produced by slab foaming. The isocyanate was added to achieve an isocyanate index (INDEX) of 94.

[0058] Details of each ingredient are as follows: • Isocyanate: Polymeric MDI, molecular weight 320, number of functional groups 2.4, NCO% 31.5%, product code Luplanate M5S, manufactured by Tosoh Corporation. • Polyether polyol 1: Polypropylene glycol, number average molecular weight 2000, number of functional groups 2.0, product code Sannix PP-2000, manufactured by Sanyo Chemical Industries, Ltd. • Polyether polyol 2: Polypropylene glycol, number average molecular weight 400, number of functional groups 2.0, product code Sannix PP-400, manufactured by Sanyo Chemical Industries, Ltd. • Polyester polyol 1: Polycaprolactone, number average molecular weight 500, number of functional groups 2.0, product code PLACCEL205U, manufactured by Asahi Glass Co., Ltd. • Foam stabilizer: Silicone foam stabilizer, product number SZ-1952, manufactured by Toray Dow Corning Co., Ltd. • Catalyst: Iron catalyst, part number FIN-P1, manufactured by Nippon Chemical Industrial Co., Ltd. • Antioxidant: Hindered phenol antioxidant, part number IRGANOX 1135, manufactured by BASF Japan. • Filler: Aluminum hydroxide, part number CW-325LV, manufactured by Sumitomo Chemical Co., Ltd. Pigment: Carbon black, part number PU-8323, manufactured by DIC Corporation. • Desiccant: Zeolite, Part No. Molecular Sieve 3APOWDER, manufactured by Union Showa Co., Ltd.

[0059] [Table 2]

[0060] 4. Preparation of polyurethane resin decomposition agent and polyurethane resin decomposition treatment Polyurethane resin decomposition agents for the examples and comparative examples, containing the components listed in Tables 3 to 6, were prepared. The polyurethane foam (polyurethane resin) described above was decomposed using the polyurethane resin decomposition agents for the examples and comparative examples.

[0061] Details of each component are as follows: Ethylene glycol: Molecular weight 62, number of functional groups 2 Glycerin: Molecular weight 92, number of functional groups 3 • Diethylene glycol: Molecular weight 106, number of functional groups 2 • Polyethylene glycol 1: Number average molecular weight 200, number of functional groups 2 • Polyethylene glycol 2: Number average molecular weight 400, number of functional groups 2 • Polypropylene glycol 1: Number average molecular weight 400, number of functional groups 2 • Polypropylene glycol 2: Number average molecular weight 750, number of functional groups 3 • Polypropylene glycol 3: Number average molecular weight 1000, number of functional groups 2 • Polypropylene glycol 4: Number average molecular weight 2000, number of functional groups 2 • Polypropylene glycol 5: Number average molecular weight 3000, number of functional groups 3 • Tertiary amine compound: diazabicycloundecene • Potassium hydroxide Polypropylene glycol 1 to polypropylene glycol 5 are examples of secondary hydroxyl group-containing polyols with a number average molecular weight of 100 or more. Polypropylene glycol 1 to polypropylene glycol 4 are examples of secondary hydroxyl group-containing polyols with a number average molecular weight of 100 to 2800.

[0062] In a 1 L separable flask, the polyurethane resin decomposition agents of the examples and comparative examples were added to 100 g of ester-based polyurethane resin. The amounts of each component of the polyurethane resin decomposition agent added are shown in Tables 2 to 5. After adding the polyurethane resin decomposition agent, the mixture was heated at 170 ± 10 °C for 5 hours with stirring to obtain the polyurethane decomposition product.

[0063] [Table 3]

[0064] [Table 4]

[0065] [Table 5]

[0066] [Table 6]

[0067] 5. Preparation of polyurethane foam Isocyanate (Crude MDI, product code MR200, manufactured by Tosoh Corporation) was added to the polyurethane decomposition product to achieve an isocyanate index (INDEX) of 100. The mixture was stirred with a hand mixer for 2 minutes, then formed into a sheet and cured in a 120°C hot air drying oven for 5 minutes.

[0068] 6. Evaluation Method <Polyurethane resin is biodegradable> The degradability of polyurethane resin was evaluated visually according to the following criteria. The evaluation criteria are as follows: A: The polyurethane resin has decomposed sufficiently. B: The polyurethane resin has not decomposed sufficiently.

[0069] <Polyester polyol biodegradable> The degradability of polyester polyols was evaluated using the following methods. IR, GPC, and LC / MS measurements were performed on the polyurethane degradation products of the examples and comparative examples to confirm the presence of ester bonds. The criteria for evaluation are as follows: A: Sufficient ester bonds remain in the polyurethane decomposition products. B: The polyurethane decomposition product contains few ester bonds, indicating that the decomposition of ester bonds is progressing.

[0070] <compatibility> The compatibility of polyurethane decomposition products was evaluated visually according to the following criteria. The criteria for evaluation are as follows: A: The polyurethane decomposition product is in a single phase. B: The polyurethane decomposition products have separated into two phases.

[0071] <Effervescent> The foamability of polyurethane foam manufactured using polyurethane decomposition products was evaluated visually according to the following criteria. If polyurethane foam was not manufactured, a "-" is indicated in the foamability evaluation column. A: The polyurethane foam has good foaming properties. B: The foaming properties of the polyurethane foam are poor. For example, excessive heat is generated during the mixing of the composition for polyurethane foam, causing the reaction to proceed too quickly and solidify, making it impossible to mold.

[0072] <Judgment> The decomposing agents for polyurethane resins in the examples and comparative examples were evaluated according to the following criteria. A: The evaluations for "polyurethane resin degradability," "polyester polyol degradability," "compatibility," and "foaming properties" are all "A." B: The evaluations for "polyurethane resin degradability," "polyester polyol degradability," and "compatibility" are all "A," while the evaluation for "foaming properties" is "B." C: One or more of the following evaluations are "B": "Polyurethane resin degradability", "Polyester polyol degradability", and "Compatibility".

[0073] 7.Results The evaluation results are listed in Tables 3 through 6. Examples 1-8 satisfy the requirement of containing 0.2 to 3 parts by mass of a tertiary amine compound per 100 parts by mass of a secondary hydroxyl group-containing polyol with a number average molecular weight of 100 or more. Examples 1-8 received a rating of "A" or "B". On the other hand, Comparative Examples 1-18 do not satisfy the above requirement. Comparative Examples 1-18 received a rating of "C".

[0074] It was suggested that a polyurethane resin decomposition agent satisfying the above requirements can suppress the decomposition of polyether polyols while ensuring the decompositionability of the polyurethane resin. Furthermore, it was suggested that a single-phase polyurethane decomposition product can be suitably obtained by using a polyurethane resin decomposition agent satisfying the above requirements. Moreover, it was suggested that the polyurethane decomposition product obtained using a polyurethane resin decomposition agent satisfying the above requirements can be suitably used in the production of polyurethane foam.

[0075] Of Examples 1-8, Examples 1-7, in which the number-average molecular weight of the secondary hydroxyl group-containing polyol was between 100 and 2800, received a rating of "A". When the number-average molecular weight of the secondary hydroxyl group-containing polyol is between 100 and 2800, polyurethane foam can be easily produced, making it even more useful in that foamability can be ensured.

[0076] The following inventions can also be understood from the contents of this specification. • A secondary hydroxyl group-containing compound with a molecular weight of 100 or more was used as a decomposition agent. A method for decomposing polyurethane resins containing ester bonds. • Contains a secondary hydroxyl group-containing compound with a molecular weight of 100 or more. A decomposing agent for polyurethane resins containing ester bonds. The polyurethane resin decomposition agent described above contains a secondary hydroxyl group-containing compound with a molecular weight of 100 or more, thereby preferentially decomposing urethane bonds over ester bonds.

[0077] 8. Effects of the Examples This embodiment provides a novel technique for decomposing polyurethane resins manufactured using polyester polyols. For example, this embodiment made it possible to decompose ester-based polyurethane resins with glycol, which has been considered difficult in the past.

[0078] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of this disclosure.

Claims

1. A decomposition agent for polyurethane resins manufactured using polyester polyols, A decomposition agent for polyurethane resins, comprising 0.2 to 3 parts by mass of a tertiary amine compound per 100 parts by mass of a secondary hydroxyl group-containing polyol having a number average molecular weight of 100 or more.

2. The polyurethane resin decomposition agent according to claim 1, wherein the secondary hydroxyl group-containing polyol has a number average molecular weight of 100 or more and 2800 or less.

3. The polyurethane resin decomposition agent according to claim 1 or claim 2, wherein the secondary hydroxyl group-containing polyol is polypropylene glycol.

4. A method for producing a polyurethane decomposition product, comprising decomposing the polyurethane resin with the polyurethane resin decomposition agent described in claim 1 or claim 2.

5. A polyurethane decomposition product obtained by decomposing the polyurethane resin with the polyurethane resin decomposition agent described in claim 1 or claim 2.

6. A polyurethane foam obtained from a composition comprising part or all of the polyurethane decomposition product described in claim 5 and an isocyanate.

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