Method for producing recycled polyol and recycled polyol

Abstract

To provide a new technique for obtaining a regenerated polyol from a polyester-based polyurethane resin.SOLUTION: The method for producing the regenerated polyol is a method for producing a regenerated polyol having an amide bond and an ester bond in a molecular chain, wherein an organic carboxylic acid having two or more carboxyl groups and / or an anhydride thereof is added to a decomposition treatment product obtained by treating a polyurethane resin using a raw material containing a polyester-based polyol with a polyol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing recycled polyol and recycled polyol. [Background technology]

[0002] There is a need for technology to chemically decompose polyurethane resin and recycle it as a raw material for recycled polyurethane resin.

[0003] Patent Document 1 describes a method for recycling polyurethane foam in which an azole compound is added to polyurethane foam, followed by thermal decomposition to obtain a polyol component as a decomposition product. This method describes that by using an azole compound as a decomposition agent, the urethane bonds that are the crosslinking points of the polyurethane foam are selectively decomposed, and the decomposition of ester bonds is suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-323009 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for a new technology for obtaining recycled polyol from a polyurethane resin (hereinafter also referred to as a polyester-based polyurethane resin) made using a raw material containing a polyester-based polyol.

[0006] The present disclosure aims to provide a novel technique for obtaining recycled polyol from polyester-based polyurethane resin. The present disclosure can be realized in the following aspects. [Means for solving the problem]

[0007] A method for producing a recycled polyol having an amide bond and an ester bond in the molecular chain, A decomposition product obtained by treating a polyurethane resin using a raw material containing a polyester polyol with polyols is subjected to A method for producing recycled polyol by adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride. [Effects of the Invention]

[0008] According to the present disclosure, a novel technology can be provided for obtaining recycled polyol from polyester-based polyurethane resin. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram (part 1) showing the melting points, boiling points, and structural formulas of polycarboxylic acids or acid anhydrides. [Figure 2] FIG. 2 is a diagram (part 2) showing the melting points, boiling points, and structural formulas of polycarboxylic acids or acid anhydrides. DETAILED DESCRIPTION OF THE INVENTION

[0010] Here, a preferred example of the present disclosure will be described. [1] A method for producing a recycled polyol having an amide bond and an ester bond in the molecular chain, A decomposition product obtained by treating a polyurethane resin using a raw material containing a polyester polyol with polyols is subjected to A method for producing recycled polyol by adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride. [2] The method for producing a recycled polyol according to [1], wherein the polyol is an alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mg KOH / g or more) and / or an alkanediol. [3] A recycled polyol having an amide bond and an ester bond in the molecular chain, A decomposition product obtained by treating a polyurethane resin using a raw material containing a polyester polyol with polyols is subjected to A recycled polyol obtained by adding an organic carboxylic acid and / or its anhydride having two or more carboxyl groups. [4] The recycled polyol according to [3], wherein the polyol is an alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mg KOH / g or more) and / or an alkanediol.

[0011] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "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". In addition, in this specification, the upper limit and lower limit of each numerical range can be combined in any way.

[0012] 1.Recycled polyol manufacturing method The method for producing recycled polyol is a method for producing recycled polyol having amide bonds and ester bonds in the molecular chain, and involves adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride to a decomposition product obtained by treating a polyurethane resin made from a raw material containing a polyester polyol with polyols. In the following explanation, the process of adding an organic carboxylic acid having two or more carboxyl groups and / or its anhydride to the decomposition product is also simply referred to as an acid addition process.

[0013] (1) Polyurethane resin The polyurethane resin used in the method for producing recycled polyol of the present disclosure is a polyurethane resin made using a raw material containing a polyester-based polyol.

[0014] 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. Only one type of polyester polyol may be included, or two or more types may be included.

[0015] The compound having at least two hydroxy groups is not particularly limited. Examples of the compound having at least two hydroxy 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. The compound having at least two hydroxy groups may be one type or two or more types. As the compound having at least two hydroxy groups, a diol and a polyhydric alcohol are preferably used in combination, and diethylene glycol and trimethylolpropane are more preferably used in combination.

[0016] The compound having at least two carboxyl groups is not particularly limited. Examples of the compound having at least two carboxyl groups include compounds selected from the group consisting of malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid, pimelic acid, azelaic acid, sebacic acid, oxalic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and hemellitic acid. The compound having at least two carboxyl groups may be one type or two or more types. The compound having at least two carboxyl groups is preferably an aliphatic dibasic acid, more preferably adipic acid.

[0017] The cyclic ester is, for example, a lactone, which is a cyclic ester having a carbon number of 2 to 15, preferably a carbon number of 4 to 10. Specific examples of the cyclic ester include ε-caprolactone and methylvalerolactone.

[0018] The raw material polyol of the polyester polyurethane resin may include a polyol other than a polyester polyol. Examples of polyols other than a polyester polyol include polyether polyols, polyetherester polyols, polycarbonate diols, and polyols having a carbon-carbon bond main chain. The various polyols exemplified as polyols other than a polyester polyol may be used alone or in combination of two or more.

[0019] The content of the polyester polyol is preferably 30 parts by mass or more and 100 parts by mass or less, more preferably 40 parts by mass or more and 100 parts by mass or less, and may be 50 parts by mass or more, or 60 parts by mass or more, based on 100 parts by mass of the total raw polyols of the polyester polyurethane resin.

[0020] The polyester-based polyurethane resin is not particularly limited as long as a raw material containing a polyester-based polyol is used. The polyurethane resin is, for example, a polyurethane foam. The polyurethane foam may be any of a flexible polyurethane foam, a semi-rigid polyurethane foam, and a rigid polyurethane foam. The polyurethane foam may be an open-cell polyurethane foam or a closed-cell polyurethane foam. The polyurethane foam may be a pulverized product pulverized to a predetermined size. The polyurethane foam may also be cut to a predetermined size. The polyurethane foam may be, for example, scraps discarded during the polyurethane foam manufacturing process or used polyurethane foam to be discarded.

[0021] (2) Polyols (decomposers) The polyols are used as decomposition agents. The polyols are not particularly limited as long as they can produce decomposition products. The polyols can be used alone or in combination of two or more.

[0022] The polyol is preferably an alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mgKOH / g or more) and / or an alkanediol. The upper limit of the hydroxyl value of the alkylene oxide adduct of alcohol is not particularly limited, and is, for example, 1200 mgKOH / g or less. The alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mgKOH / g or more) is preferably bifunctional. The alkylene oxide adduct of bifunctional alcohol can be obtained, for example, by reacting an alkylene oxide such as ethylene oxide or propylene oxide with a bifunctional alcohol as an initiator. Specific examples of alkylene oxide adducts of alcohol include diethylene glycol, polyethylene glycol with a hydroxyl value of 500 mgKOH / g or more, dipropylene glycol, and polypropylene glycol with a hydroxyl value of 500 mgKOH / g or more. The alkanediol is more preferably selected from the group consisting of alkane diols having from 2 to 10 carbon atoms and mixtures thereof. Specific examples of alkane diols having from 2 to 10 carbon atoms include 1,4-butanediol, 3-methyl,1,5-pentanediol, ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl,1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and 2-butyl,2-ethyl,1,3-propanediol.

[0023] The number of functional groups in the recycled polyol can be adjusted by using alkylene oxide adducts of the above alcohols (limited to those with a hydroxyl value of 500 mgKOH / g or more) and / or tri- or higher-functional alcohols as polyols other than alkanediols. Even in this case, the amount of tri- or higher-functional alcohol is preferably 10 parts by mass or less, based on 100 parts by mass of the total polyols. The tri- or higher-functional alcohol may be added, for example, during decomposition of the polyester polyurethane resin or during acid addition treatment. Specific examples of tri- or higher-functional alcohols are as follows: Trifunctional alcohol: glycerin, trimethylolpropane, etc. Tetrafunctional alcohol: pentaerythritol, tetramethylolcyclohexane, etc. Hexafunctional alcohol: sorbitol, mannitol, etc. Octafunctional alcohol: sucrose, etc.

[0024] The amount of polyols added is not particularly limited. From the viewpoint of sufficiently decomposing the polyester polyurethane resin, the amount of polyols added is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, relative to 100 parts by mass of polyester polyurethane resin. The amount of the decomposing agent added is preferably 250 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 175 parts by mass or less, taking into account the effect on reactivity and physical properties when the recycled polyol is reused as a polyurethane resin raw material, etc. From these viewpoints, the amount of the decomposing agent added is preferably 15 parts by mass or more and 250 parts by mass or less, more preferably 20 parts by mass or more and 200 parts by mass or less, and even more preferably 25 parts by mass or more and 175 parts by mass or less. In this specification, the amount of polyols added refers to the total amount of an alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mgKOH / g or more) and / or an alkanediol and the tri- or higher functional alcohol.

[0025] (3) Catalyst The decomposing agent may be used in combination with a catalyst. The catalyst is not particularly limited. The catalyst is preferably one that is used in producing polyurethane resins. The catalyst may be used alone or in combination of two or more.

[0026] The catalyst is preferably an amine compound, and more preferably a tertiary amine compound not containing a hydroxyl group. Examples of the catalyst include one or more selected from the group consisting of diazabicycloundecene, triethylamine, tripropylamine, tributylamine, hexadecyldimethylamine, N-methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, N,N,N',N'-tetramethylhexanediamine, N,N,N',N'-tetramethylpropanediamine, N,N,N',N'',N''-pentamethyldiethylenetriamine, N,N',N'-trimethylaminoethylpiperazine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, and 1,4-diazabicyclo[2.2.2]octane.

[0027] A metal catalyst may be used as the catalyst. The metal catalyst may be used in combination with the above-mentioned amine compound. The metal catalyst is, for example, one or more selected from the group consisting of stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin mercaptide, dioctyltin thiocarboxylate, lead octoate, potassium acetate, potassium octoate, tetra-n-butoxytitanium, and tetra-i-propoxytitanium. The metal catalyst may be added, for example, during decomposition of the polyurethane resin or during acid addition treatment.

[0028] The amount of catalyst added is not particularly limited. From the viewpoint of sufficiently decomposing the polyester polyurethane resin, the amount of catalyst added is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the polyester polyurethane resin. In consideration of the effect on reactivity and physical properties when the decomposition product of the polyester polyurethane resin is reused as a polyurethane resin raw material, the amount of catalyst added is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. From these viewpoints, the amount of catalyst added is preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.3 parts by mass or more and 4 parts by mass or less, and even more preferably 0.5 parts by mass or more and 3 parts by mass or less.

[0029] (4) Decomposition products The decomposition product is obtained by reacting a polyester-based polyurethane resin with a decomposing agent. The decomposition product may be obtained by treating a polyester-based polyurethane resin with a decomposing agent and a catalyst.

[0030] The conditions for decomposing the polyester-based polyurethane resin are not particularly limited. From the viewpoint of improving the decomposition rate, the polyester-based polyurethane resin may be heated together with a decomposing agent during the decomposition treatment of the polyester-based polyurethane resin. When heating the polyester-based polyurethane resin together with the decomposing agent, it is preferable to stir the mixture of the polyester-based polyurethane resin and the decomposing agent.

[0031] 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, from the viewpoint of improving the decomposition rate while suppressing the decomposition of the polyol as a polyurethane decomposition product, i.e., the polyol derived from the raw material polyol. The decomposition treatment time is, for example, from 10 minutes to 24 hours, or may be from 30 minutes to 10 hours. The end point of the decomposition treatment time may be appropriately set while checking the progress of decomposition of the polyurethane resin depending on the size of the polyester-based polyurethane resin, whether stirring is performed, etc. Furthermore, when decomposing a polyester-based polyurethane resin at room temperature (e.g., 25°C) or higher and lower than 80°C, the decomposition treatment time may be set to longer than 24 hours.

[0032] The decomposition products include, for example, components derived from the raw material polyol of the polyester polyurethane resin. Under conditions in which the urethane bonds of the polyester polyurethane resin are decomposed by the polyols, the ester bonds can also be decomposed by the polyols. When the ester bonds of the polyester polyol, which is one of the raw material polyols, are decomposed by the polyols, a compound A having a carboxyl group and a compound B having a hydroxyl group can be produced. The decomposition products also include, for example, amine compounds C derived from isocyanates, which are raw materials for polyester-based polyurethane resins.

[0033] In the decomposition product, the compound A having a carboxyl group produced by decomposition of the polyester polyol may react (including the formation of a salt) with a portion of the amine compound, such as the amine compound C described above. If the amine compound remains in the recycled polyol, its high reactivity makes it difficult to balance the reaction when the recycled polyol is reused. Furthermore, if the urethane resin uses an aromatic isocyanate, there is a concern that harmful aromatic amines may be produced. In this regard, the method for producing recycled polyol disclosed herein has the advantage that the acid derived from the polyester polyol can reduce the impact of the amine compound after the decomposition process.

[0034] In addition to the above, the decomposition product may also include polyols used as decomposition agents, as well as flame retardants, catalysts, and other additives contained in the polyester-based polyurethane resin.

[0035] The state of the decomposition product is not particularly limited. The decomposition product may be in a single-phase state in which a phase containing a polyol component (hereinafter also referred to as a polyol phase) and a phase containing an amine compound (hereinafter also referred to as an amine phase) are not separated, or may be in a state in which the phase containing a polyol component and the phase containing an amine compound are separated. The technology of the present disclosure can be said to be a highly versatile technology that can be applied regardless of the state of the decomposition product.

[0036] (5) Addition of organic carboxylic acids and / or their anhydrides having two or more carboxyl groups (polycarboxylic acids and / or their anhydrides) The polycarboxylic acid and / or anhydride thereof is not particularly limited. The number of carboxyl groups in the polycarboxylic acid and / or anhydride thereof is preferably 2 or more and 4 or less, and more preferably 2 or 3. The polycarboxylic acid and / or anhydride thereof may be an aromatic carboxylic acid or an aliphatic carboxylic acid. The number of carbon atoms in the polycarboxylic acid and / or anhydride thereof is preferably from 2 to 20, more preferably from 3 to 15, and even more preferably from 4 to 12. The number of carbon atoms here includes the number of carbon atoms contained in the carboxyl group. The boiling point or decomposition temperature of the polycarboxylic acid and / or its anhydride under atmospheric pressure is preferably 135° C. or higher, more preferably 140° C. or higher, and even more preferably 150° C. or higher. The upper limit of the boiling point or decomposition temperature is not particularly limited, and is usually 500° C. or lower. The melting point of the polycarboxylic acid and / or anhydride thereof under atmospheric pressure is preferably 300° C. or lower, more preferably 250° C. or lower, and even more preferably 220° C. or lower. The lower limit of the melting point is not particularly limited and is usually 20° C. or higher, and may be 50° C. or higher, 80° C. or higher, or 95° C. or higher.

[0037] Examples of polycarboxylic acids and / or anhydrides thereof include aliphatic dicarboxylic acids having 4 to 12 carbon atoms, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, terephthalic acid, and isophthalic acid, aromatic dicarboxylic acids, and mixtures thereof. The melting points, boiling points, and structural formulas of the above compounds are shown in Figure 1. Compounds with a blank or "-" in the boiling point column all have a boiling point or decomposition temperature of 150°C or higher.

[0038] In the method for producing recycled polyol, the amount of polycarboxylic acid and / or its anhydride added is not particularly limited. In the method for producing recycled polyol, it is preferable to add polycarboxylic acid and / or its anhydride to a decomposition product obtained by treating a polyester-based polyurethane resin with polyols so that the ratio of the molar amount of hydroxyl groups in the decomposition product to the molar amount of carboxyl groups in the polycarboxylic acid and / or its anhydride is 0.8 or more. The ratio of the molar amount of carboxyl groups to the molar amount of hydroxyl groups in the decomposition product is more preferably 1.0 or more, even more preferably 1.05 or more, and particularly preferably 1.1 or more. The upper limit of the ratio of the molar amount of hydroxyl groups in the decomposition product to the molar amount of carboxyl groups in the polycarboxylic acid and / or its anhydride is not particularly limited, and may be, for example, 4.0 or less, 3.5 or less, or 3.0 or less. Within the above range, the viscosity of the recycled polyol is not too high, making it easy to handle when reused. Also, within the above range, the hydroxyl value after synthesis of the recycled polyol, i.e., the number average molecular weight of the recycled polyol, can be designed within a preferred range. Therefore, for example, when the recycled polyol is reused as a polyurethane resin raw material, it is easy to ensure the physical properties of the polyurethane resin, which is suitable.

[0039] The molar amount of hydroxyl groups in the decomposition product can be calculated by measuring the hydroxyl value in accordance with JIS K1557-1:2007. The molar amount of carboxyl groups can be calculated as the sum of the value obtained by multiplying the molar amount of polycarboxylic acid to be added by the number of carboxyl groups and the value obtained by multiplying the molar amount of acid anhydride to be added by twice the number of acid anhydride groups.

[0040] In a method for producing recycled polyol, a polycarboxylic acid and / or anhydride thereof may be added to the decomposition product and heated to promote the synthesis of recycled polyol. The heating temperature is preferably 150°C or higher, and may be 160°C or higher, 170°C or higher, or 180°C or higher, to promote the formation of amide bonds and ester bonds in the recycled polyol. The upper limit of the heating temperature is not particularly limited. The upper limit of the heating temperature may be, for example, 280°C or lower, 260°C or lower, 240°C or lower, or 220°C or lower, to suppress the vaporization and decomposition of the organic carboxylic acid.

[0041] The heating may be carried out by utilizing the residual heat generated during the decomposition of the polyester polyurethane resin. For example, before the heated decomposition product is cooled to room temperature, a polycarboxylic acid and / or anhydride thereof may be added and the heating may be carried out. This can shorten the heating and cooling time and reduce the amount of energy, such as electricity, required for producing recycled polyol.

[0042] The heating time is, for example, from 10 minutes to 24 hours, and may be from 30 minutes to 10 hours. The end point of the heating time may be appropriately set while confirming that the total amine value and / or hydroxyl value of the decomposition product have been sufficiently reduced.

[0043] When the polycarboxylic acid and / or its anhydride are added and dehydration condensation is carried out, the reaction may be carried out under reduced pressure. Furthermore, when the polycarboxylic acid and / or its anhydride are added and dehydration condensation is carried out, dry gas may be supplied.

[0044] In the method for producing recycled polyol, an esterification catalyst may be added together with the polycarboxylic acid and / or its anhydride to promote the synthesis of the recycled polyol. The esterification catalyst is not particularly limited. Examples of the esterification catalyst include metal compounds such as titanium, aluminum, zinc, manganese, antimony, tin, zirconium, and germanium; alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; phosphorous compounds; phosphoric acid compounds; and amine compounds. Specific examples of titanium compounds include tetrabutyl orthotitanate, tetraisobutyl orthotitanate, tetraisopropyl orthotitanate, tetraoctadecyl orthotitanate, tetra(tetradecyl) orthotitanate, tetraoctyl orthotitanate, dioctyldihydroxyoctyl orthotitanate, and dioctyldi(tetradecyl) orthotitanate.

[0045] The amount of the esterification catalyst added is preferably 0.001 to 1 part by mass, more preferably 0.005 to 0.5 parts by mass, and even more preferably 0.01 to 0.2 parts by mass, per 100 parts by mass of the polyester polyurethane resin.

[0046] (6) Synthesis of recycled polyols containing amide and ester bonds in the molecular chain When an amino group and a carboxyl group undergo dehydration condensation, an amide bond is formed. When a hydroxyl group and a carboxyl group undergo dehydration condensation, an ester bond is formed. In the decomposition product, compounds having amino groups, such as the above-mentioned amine compound C, are present, as well as compounds having hydroxyl groups, such as the above-mentioned compound B having hydroxyl groups and the polyols used as decomposition agents. The method for producing recycled polyol disclosed herein can synthesize recycled polyols having amide bonds and ester bonds in the molecular chain (hereinafter also referred to as polyamide-polyester polyols) by dehydration condensation using polycarboxylic acids and / or their anhydrides having multiple carboxyl groups in the molecule. Note that the technology disclosed herein is not limited to this speculated reaction mechanism.

[0047] The acid-added product obtained by adding a polycarboxylic acid and / or its anhydride to the decomposition product is preferably in a single-phase state, where the liquid phase containing the recycled polyol is not clearly separated. That is, it is preferable that the liquid phase containing the recycled polyol is in a homogeneous state. When the liquid phase containing the recycled polyol is in a homogeneous state, the acid-added product can be directly obtained as a recycled polyol. In this way, no special removal operation is required after the reaction with the polycarboxylic acid and / or its anhydride, and a recycled polyurethane raw material can be obtained simply and without generating waste. Note that, if the acid-added product contains solids or a second liquid phase that is separated from the liquid phase containing the recycled polyol, the solids or second liquid phase can be removed to obtain the recycled polyol. The solids in the acid-added product can be removed, for example, by filtering the obtained acid-added product. Alternatively, if the acid-added product contains solids or a second liquid phase, the recycled polyol can be obtained by extracting only the liquid phase containing the recycled polyol from the acid-added product. The obtained recycled polyol can be used as a recycled raw material as is. The molecular weight, hydroxyl value, amine value, and uses of the recycled polyol will be described later.

[0048] 2.Recycled polyol The recycled polyol is a recycled polyol having amide bonds and ester bonds in the molecular chain, and is obtained by adding an organic carboxylic acid and / or its anhydride having two or more carboxyl groups to a decomposition product obtained by treating a polyurethane resin made from raw materials containing polyester-based polyol with polyols.

[0049] In the explanation of recycled polyols, for polyurethane resins, polyols, decomposition products, and organic carboxylic acids and / or their anhydrides having two or more carboxyl groups (polycarboxylic acids and / or their anhydrides), the explanations of "(1) Polyurethane resins," "(2) Polyols (decomposers)," "(4) Decomposition products," and "(5) Addition of organic carboxylic acids and / or their anhydrides having two or more carboxyl groups (polycarboxylic acids and / or their anhydrides)" in the "1. Method for producing recycled polyols" section apply as is, and the description thereof will be omitted.

[0050] The recycled polyol can be suitably obtained, for example, by the above-mentioned method for producing recycled polyol. In the explanation of recycled polyol, the explanations of "(3) Catalyst" and "(6) Synthesis of recycled polyol having amide bonds and ester bonds in the molecular chain" in the section "1. Method for producing recycled polyol" can be applied as is.

[0051] The hydroxyl value of the recycled polyol is smaller than that of the decomposition product. The hydroxyl value of the recycled polyol can be appropriately set, for example, in the range of 20 mg KOH / g or more and 400 mg KOH / g or less. The hydroxyl value of the recycled polyol can be controlled, for example, by adjusting the number of functional groups and the amount of polycarboxylic acid and / or its anhydride added, the number of functional groups and the amount of polyols used as decomposition agents, etc. The hydroxyl value of the recycled polyol refers to the hydroxyl value of the recycled polyol obtained from the acid-added treatment product, measured in accordance with JIS K1557-1:2007.

[0052] The amine value of the recycled polyol is lower than that of the decomposition product. The amine value of the recycled polyol is preferably 35 mg KOH / g or less, more preferably 30 mg KOH / g or less, and may be 25 mg KOH / g or less, 20 mg KOH / g or less, 15 mg KOH / g or less, or 10 mg KOH / g or less. The lower limit of the amine value of the recycled polyol is not particularly limited. The amine value of the recycled polyol may be 0 mg KOH / g or more. The amine value of the recycled polyol means the total amine value of the recycled polyol obtained from the acid-added treatment product, measured in accordance with JIS K1557-7:2011.

[0053] The number average molecular weight of the recycled polyol is not particularly limited. For example, the number average molecular weight of the recycled polyol may be 1,000 to 10,000, 1,500 to 7,000, or 2,000 to 5,000. The number average molecular weight of the recycled polyol can be measured as a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0054] The average number of functional groups of the recycled polyol is not particularly limited. The average number of functional groups of the recycled polyol may be, for example, 2 to 6, 2.5 to 4.5, or 2.5 to 3.5. The average number of functional groups of the recycled polyol can be controlled, for example, by adjusting the number of functional groups of the polycarboxylic acid and / or its anhydride, the number of functional groups of the polyols used as decomposing agents, etc. When the above-mentioned trifunctional or higher polyols are used, the average number of functional groups may be controlled by adjusting the number of functional groups of the trifunctional or higher polyols, the amount added, etc.

[0055] If the hydroxyl value and amine value of the recycled polyol are within the above ranges, the recycled polyol can be suitably used as a recycled raw material. The use of the recycled polyol is not particularly limited. For example, the recycled polyol can be used as a recycled raw material for obtaining a recycled polyurethane resin. A method for producing recycled polyurethane resin involves, for example, mixing recycled polyol with isocyanate to obtain polyurethane resin. Recycled polyurethane resin can be produced by known methods. Foaming methods for obtaining polyurethane foam include slab foaming and mold foaming, and either molding method may be used. Slab foaming is a method in which a mixture of recycled polyol and isocyanate is discharged onto a belt conveyor and foamed at atmospheric pressure and room temperature. On the other hand, mold foaming is a method in which a mixture of recycled polyol and isocyanate is filled into a mold (forming die) and foamed within the mold.

[0056] 3. Effects of this embodiment Conventionally, polyester-based polyurethane resins have been difficult to recycle as raw materials because the ester bonds of polyester-based polyols are also decomposed under the conditions that decompose the urethane bonds. Furthermore, polyester-based polyurethane resins have poorer hydrolysis resistance than polyether-based polyurethane resins, so their applications when reused as recycled materials (rebonded foam) have been limited. In particular, they have tended to be avoided as polyurethane resins for automobiles.

[0057] According to this embodiment, the ester bond portion of the polyester-based polyurethane resin is decomposed, and then the resulting resin is resynthesized as a polyamide-polyester-based polyol by dehydration condensation with a polycarboxylic acid and / or its anhydride. Therefore, the polyester-based polyurethane resin can be chemically recycled as a recycled polyol and used in various applications.

[0058] In the method for producing recycled polyols according to this embodiment, polyols used as decomposing agents during the synthesis of recycled polyols can ultimately be incorporated into the main chain of the recycled polyol. Generally, the use of polyols with a high hydroxyl value, i.e., low-molecular-weight polyols, can increase the decomposition rate of polyurethane resins. On the other hand, the inclusion of a large amount of low-molecular-weight polyols in recycled polyols can result in a hard recycled polyurethane resin. In this regard, in this embodiment, even when low-molecular-weight polyols are used to increase the decomposition rate of polyurethane resins, the incorporation of low-molecular-weight polyols into the recycled polyol can reduce the amount of low-molecular-weight polyols contaminated in the recycled polyol. As a result, the flexibility of recycled polyol applications can be ensured, making it possible to use the recycled polyol, for example, in the production of flexible recycled polyurethane foams.

[0059] Generally, chemical decomposition of polyurethane resins produces amine compounds. If amine compounds remain in recycled polyols, their high reactivity makes it difficult to balance the reactions during reuse. Furthermore, when an aromatic isocyanate is used in a polyurethane resin, there is a concern that harmful aromatic amines may be generated. According to this embodiment, by using amine compounds in the synthesis of polyamide-polyester polyols, the amount of amine compounds remaining in the recycled polyol can be reduced. Furthermore, as described above, the acid generated by decomposition of polyester polyols can reduce the amount of amine compounds during the decomposition process. Furthermore, the addition of polycarboxylic acids and / or their anhydrides during resynthesis can further reduce the amount of amine compounds. Therefore, the reaction balance can be favorably maintained when recycling recycled polyols. Furthermore, even when aromatic isocyanates are used, the generation of harmful aromatic amines can be suppressed.

[0060] Furthermore, in the method for producing recycled polyol of this embodiment, the number average molecular weight, number of functional groups, etc. of the recycled polyol can be appropriately designed by appropriately selecting the polyols used as decomposition agents and the polycarboxylic acid and / or its anhydride used during resynthesis. Therefore, a recycled polyol suitable for use after reuse can be obtained.

[0061] In addition, in the method for producing recycled polyol of this embodiment, when heating, decompression, etc. are performed during the dehydration condensation, volatile impurities (e.g., siloxane compounds, etc.) can be suitably removed. Therefore, a relatively high purity raw material can be obtained without any special purification work apart from the dehydration condensation process. [Example]

[0062] 1. Manufacturing of decomposable polyurethane resin Polyurethane foam compositions (liquids A and B) were prepared in the proportions shown in Table 1, and polyester-based polyurethane foams were produced as the decomposable polyurethane resin by slab foaming. The densities of the resulting polyester-based polyurethane foams were measured in accordance with JIS K7222:2005. The measured densities are also shown in Table 1.

[0063] The details of each raw material are as follows: Polyester polyol: Poly(diethylene glycol / trimethylolpropane)-alt-adipic acid, molecular weight 2500, functionality 2.7, hydroxyl value: 60.5 mg KOH / g Amine catalyst: Triethylenediamine Foam stabilizer: Special nonionic surfactant, BJ-100 (Kao Corporation) Foaming agent: Water Isocyanate: Tolylene diisocyanate, product name: Coronate T-80, manufactured by Tosoh Corporation, NCO%: 48.2%

[0064] [Table 1]

[0065] 2. Polyurethane resin decomposition treatment (decomposition process) In a 1 L separable flask, 100 g of the polyurethane resin to be decomposed was added with polyols (decomposers) and catalysts in the proportions shown in Table 2, and the mixture was heated at 200°C for 6 hours with stirring to obtain decomposed products of polyurethane resins of the Examples and Comparative Examples. Details of the polyols (decomposers) and catalysts are as follows: Polyols (decomposers): Diethylene glycol, alkylene oxide adduct of alcohol, hydroxyl value 1057 mg KOH / g Polyols (decomposers): 1,4-butanediol, alkanediol with 4 carbon atoms Polyols (decomposers): 3-methyl, 1,5-pentanediol, alkanediol with 6 carbon atoms Catalyst: Diazabicycloundecene (DBU)

[0066] The hydroxyl value and total amine value of the resulting decomposition product were measured in accordance with JIS K1557-1:2007 and JIS K1557-7:2011. The results are shown in Tables 2 to 4. Note that in Comparative Examples 1 and 2, the polyurethane resin was not sufficiently decomposed, and the hydroxyl value and total amine value could not be measured.

[0067] 3. Acid addition treatment of decomposition product (synthesis process) The decomposition products obtained in Examples 1 to 10 were subjected to an acid addition treatment. In a 1 L separable flask, polycarboxylic acids shown in Tables 2 to 4 were added to the decomposition product in the blending ratios shown in Tables 2 to 4. The amount of polycarboxylic acid added was adjusted so that the ratio of the molar amount of carboxyl groups to the molar amount of hydroxyl groups in the decomposition product would be the value shown in the column "molar ratio of hydroxyl groups / carboxyl groups" in Tables 2 to 4. The molar amount of hydroxyl groups in the decomposition product was calculated from the hydroxyl value of the decomposition product. The molar amount of carboxyl groups was calculated by multiplying the molar amount of polycarboxylic acid added by the number of carboxyl groups, or by multiplying the molar amount of acid anhydride added by twice the number of acid anhydride groups. For example, the molar amount of carboxyl groups in 1 mole of adipic acid was set to 2 moles.

[0068] The decomposition product was added with the polycarboxylic acid and 0.1% (0.1 g per 100 g of polyurethane resin to be decomposed) tetrabutyl orthotitanate (CAS: 5593-70-4) as an esterification catalyst, and heated at 210°C for 8 hours under reduced pressure to obtain an acid-treated product. The acid-treated product was used as a recycled polyol.

[0069] The hydroxyl value and total amine value of the resulting recycled polyol were measured in accordance with JIS K1557-1:2007 and JIS K1557-7:2011. The results are shown in Tables 2 to 4.

[0070] [Table 2]

[0071] [Table 3]

[0072] [Table 4]

[0073] 4. Evaluation The number average molecular weight, expressed as a polystyrene equivalent value, was measured by gel permeation chromatography (GPC) for the recycled polyol of Example 1. The number average molecular weight of the recycled polyol of Example 1 was 3,878.

[0074] The recycled polyol of Example 1 was analyzed by Fourier transform infrared spectroscopy (FT-IR). -1 -3100cm -1 The peak due to the NH of the amide bond was confirmed at a wave number of 1000 cm. -1 -1300cm -1 A peak derived from the ester bond was confirmed at a wave number of 1650 cm. -1 -1770cm -1 A peak derived from an amide bond was also confirmed.

[0075] 5.Results Examples 1 to 10 satisfy the following requirements (a) and (b): Comparative Examples 1 and 2 do not satisfy the following requirements (a) and (b). Requirement (a): A method for producing recycled polyol having amide bonds and ester bonds in the molecular chain. Requirement (b): A decomposition product obtained by treating a polyurethane resin using a raw material containing a polyester polyol with polyols is An organic carboxylic acid having two or more carboxyl groups and / or an anhydride thereof is added.

[0076] The number average molecular weight of the recycled polyol in Example 1 was sufficiently large. For example, the number average molecular weight of the recycled polyol in Example 1 was larger than the molecular weight of the polyester polyol used as a raw material for the polyurethane resin to be decomposed. The recycled polyol of Example 1 was found to have amide bonds and ester bonds from the results of Fourier transform infrared spectroscopy analysis. The hydroxyl values ​​of the recycled polyols of Examples 1 to 10 were all lower than the hydroxyl values ​​of the decomposition products. The total amine values ​​of the recycled polyols of Examples 1 to 10 were all lower than the hydroxyl value of the decomposition products. From the above results, it is considered that in Examples 1 to 10, recycled polyols having amide bonds and ester bonds in the molecular chain were successfully produced. On the other hand, in Comparative Examples 1 and 2, no acid addition treatment was carried out, and a recycled polyol could not be obtained.

[0077] 6. Effects of the Example According to this example, a novel technique for obtaining recycled polyol from polyester-based polyurethane resin was provided.

[0078] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the present disclosure.

Claims

1. A method for producing a recycled polyol having an amide bond and an ester bond in the molecular chain, A decomposition product obtained by treating a polyurethane resin using a raw material containing a polyester polyol with polyols is subjected to A method for producing recycled polyol, comprising adding an organic carboxylic acid having two or more carboxyl groups and / or an anhydride thereof.

2. The method for producing recycled polyol according to claim 1, wherein the polyol is an alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mg KOH / g or more) and / or an alkanediol.

3. A recycled polyol having an amide bond and an ester bond in the molecular chain, A decomposition product obtained by treating a polyurethane resin using a raw material containing a polyester polyol with polyols is subjected to A recycled polyol obtained by adding an organic carboxylic acid having two or more carboxyl groups and / or an anhydride thereof.

4. The recycled polyol according to claim 3, wherein the polyol is an alkylene oxide adduct of alcohol (limited to a hydroxyl value of 500 mg KOH / g or more) and / or an alkanediol.

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