Manufacturing method for recycled polyurethane foam

Abstract

This provides a novel technology for obtaining recycled polyurethane foam. [Solution] The method for producing recycled polyurethane foam comprises the steps of: decomposing a polyurethane foam to be decomposed with a decomposing agent to obtain a polyol composition containing polyols derived from the decomposed product; adding a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition; and producing recycled polyurethane foam using the acid-treated polyol composition as a raw material.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing recycled polyurethane foam. [Background technology]

[0002] Patent Document 1 discloses a method for decomposing and recovering polyurethane resin, which involves hydrolyzing the polyurethane resin under high temperature and high pressure to recover the resulting polyamine and / or polyol compounds. Patent Document 2 discloses a method for purifying polyols by adding an organic dicarboxylic acid or its anhydride to the decomposed and recovered polyol obtained by decomposing polyurethane resin, thereby precipitating the amine compound as a salt. Patent Document 3 discloses a method for purifying urethane resin decomposition products, characterized by obtaining purified polyols by vacuum distillation of the upper crude polyol layer of the decomposition product obtained by chemically decomposing urethane resin. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-169624 [Patent Document 2] Japanese Patent Publication No. 2000-247917 [Patent Document 3] Japanese Patent Publication No. 2007-262174 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Attempts have been made to produce recycled polyurethane foam from raw materials obtained by decomposing polyurethane foam with a decomposing agent. However, conventional methods have sometimes failed to produce recycled polyurethane foam due to poor foaming.

[0005] This disclosure is made in view of the above circumstances and aims to provide a novel technology for obtaining recycled polyurethane foam. This disclosure can be implemented in the following forms. [Means for solving the problem]

[0006] A process of decomposing a polyurethane foam to be decomposed with a decomposition agent to obtain a polyol composition containing polyols derived from the decomposition treatment product, A step of adding a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition, A method for producing recycled polyurethane foam, comprising the step of producing recycled polyurethane foam using the acid-treated polyol composition as a raw material. [Effects of the Invention]

[0007] This disclosure provides a novel technology for obtaining recycled polyurethane foam. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a vehicle seat using a seat pad according to one embodiment. [Modes for carrying out the invention]

[0009] Herein lies a preferred example of this disclosure. [1] A step of decomposing a polyurethane foam to be decomposed with a decomposition agent to obtain a polyol composition containing polyols derived from the decomposition treatment product, A step of adding a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition, A method for producing recycled polyurethane foam, comprising the step of producing recycled polyurethane foam using the acid-treated polyol composition as a raw material. [2] A method for producing recycled polyurethane foam according to [1], wherein the decomposition agent is an amine compound. [3] The decomposable polyurethane foam is a molded polyurethane foam, which is made using a polyol with a number average molecular weight of 4000 or more as a raw material. A method for producing recycled polyurethane foam according to [1] or [2], wherein the recycled polyurethane foam is molded polyurethane foam. [4] The acid-treated polyol composition comprises a recycled polyol with a number average molecular weight of 4000 or more and a component with a number average molecular weight of 1500 or less. [1] to [3] A method for producing recycled polyurethane foam according to any one of these. [5] A method for producing recycled polyurethane foam according to any one of the items [1] to [4], wherein polymer polyol is used as a raw material for the decomposable polyurethane foam. [6] The method for producing recycled polyurethane foam according to any one of [1] to [5], wherein the acid-treated polyol composition has a peak in the region of a number average molecular weight of 1500 or less in the molecular weight distribution on a standard polyol basis measured by gel permeation chromatography (GPC).

[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. Method for manufacturing recycled polyurethane foam The method for producing a recycled polyurethane foam includes a step of decomposing a decomposable polyurethane foam with a decomposing agent to obtain a polyol composition containing a polyol derived from the decomposed product (hereinafter also referred to as the first step), a step of adding a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition (hereinafter also referred to as the second step), and a step of producing a recycled polyurethane foam using the acid-treated polyol composition as a raw material (hereinafter also referred to as the third step).

[0012] 1-1 First Step The first step is a step of decomposing a decomposable polyurethane foam with a decomposing agent to obtain a polyol composition containing a polyol derived from the decomposed product. The decomposition method of reacting the decomposable polyurethane foam with a decomposing agent to obtain a decomposed product is not particularly limited. The decomposition methods of amine decomposition, glycol decomposition, and hydrolysis are suitable. The decomposition method of reacting the decomposable polyurethane foam with a decomposing agent to obtain a decomposed product is preferably a method in which the decomposed product is obtained in a phase-separated state.

[0013] (1) Decomposable Polyurethane Foam This disclosure is a highly versatile technology applicable to various polyurethane foams regardless of the type of the decomposable polyurethane foam.

[0014] This disclosure is effective when the decomposable polyurethane foam uses a polyol having a number average molecular weight of 4000 or more as a raw material and is a molded polyurethane foam. When the total amount of the polyol used as the raw material of the decomposable polyurethane foam is 100 parts by mass, the blending amount of the polyol having a number average molecular weight of 4000 or more is, for example, 10 parts by mass or more and 100 parts by mass or less, and may be 40 parts by mass or more and 100 parts by mass or less, or 60 parts by mass or more and 100 parts by mass or less. Such a decomposable polyurethane foam is usually difficult to chemically recycle. However, by passing through the above-mentioned second step of this disclosure, a molded polyurethane foam can be suitably obtained as a recycled polyurethane foam.

[0015] The present disclosure is also effective when a polymer polyol is used as a raw material for the decomposed polyurethane foam. The blending amount of the polymer polyol is, for example, 10 parts by mass or more and 80 parts by mass or less, 20 parts by mass or more and 70 parts by mass or less, or 30 parts by mass or more and 60 parts by mass or less when the total amount of the polyol used as a raw material for the decomposed polyurethane foam is 100 parts by mass. Such a decomposed polyurethane foam is usually difficult to chemically recycle. However, by passing through the above second step of the present disclosure, a molded polyurethane foam can be suitably obtained as a recycled polyurethane foam.

[0016] The decomposed polyurethane foam may be a pulverized product pulverized to a predetermined size. Further, the decomposed polyurethane foam may be a cut product cut to a predetermined size. The decomposed polyurethane foam may be, for example, a scrap discharged during the production process of the polyurethane foam or a used polyurethane foam to be discarded. The decomposed polyurethane foam is preferably a used automobile cushion in order to achieve sustainable development goals. The recycling of automobile cushions will be described later.

[0017] Examples of the decomposed polyurethane foam other than the above-mentioned molded polyurethane foam include a slab polyurethane foam formed by slab foaming in which a raw material is foamed at normal temperature under atmospheric pressure.

[0018] (2) Decomposing agent From the viewpoints of reactivity and cost, it is preferable that the decomposing agent is at least one selected from the group consisting of an amine compound and a compound having a hydroxyl group. Examples of amine compounds include 3,3'-diaminodipropylamine, diethylene glycolamine, triethylene glycolamine (CAS: 6338-55-2), 1-amino-3,6,9-trioxaundecaneyl-11-ol, 2,2'-(ethylenedioxy)bis(ethylamine), 4,7,10-Trioxa-1,13-tridecanediamine, 1,13-diamino-4,7,10-trioxatridecane, 4,9-dioxa-1,12-dodecanediamine, 1,11-diamino-3,6,9-trioxaundecane, 2-(2-aminoethoxy)ethylamine, 1,14-diamino-3,6,9,12-tetraoxatetradecaneethylenediamine, tetramethylenediamine, hexa It is preferable that the compound is one or more selected from the group consisting of methylenediamine, propanediamine, 2-ethylhexylamine, isopropanolamine, 2-(2-aminoethylamino)ethanol, 2-amino-2-hydroxymethyl-1,3-propanediol, ethylaminoethanol, aminobutanol, n-propylamine, di-n-propylamine, n-amylamine, isobutylamine, methyldiethylamine, monoethanolamine, diethanolamine, triethanolamine, cyclohexylamine, piperazine, piperidine, aniline, toluidine, benzylamine, phenylenediamine, xylylenediamine, chloroaniline, pyridine, picoline, N-methylmorpholine, and ethylmorpholine. These amine compounds can be used individually or in combination of two or more. The compound having a hydroxyl group is preferably one or more selected from the group consisting of, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentadiol, 1,6-hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, glycerin, and polyethylene glycol. These compounds having a hydroxyl group can be used individually or in combination of two or more.

[0019] The decomposition agent is preferably an amine compound. That is, the polyol composition is preferably obtained by amine decomposition. When the decomposition agent is an amine compound, the amine compound used as the decomposition agent can also be removed as a solid by adding a carboxylic acid compound. Therefore, a highly pure acid-treated polyol composition can be obtained.

[0020] The amount of decomposition agent added is not particularly limited. From the viewpoint of sufficiently decomposing the polyurethane foam to be decomposed, the amount of decomposition 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, per 100 parts by mass of the polyurethane foam to be decomposed. The amount of decomposition agent added is preferably 100 parts by mass or less, more preferably 75 parts by mass or less, and even more preferably 50 parts by mass or less, taking into consideration the effect on the reactivity and physical properties when the acid-treated polyol composition is reused as a raw material for recycled polyurethane foam. From these viewpoints, the amount of decomposition agent added is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 5 parts by mass or more and 75 parts by mass or less, and even more preferably 8 parts by mass or more and 50 parts by mass or less.

[0021] (3) Decomposition catalyst In a decomposition reaction using a decomposition agent, a further decomposition catalyst may be added as needed. The decomposition catalyst is not particularly limited. The decomposition catalyst is preferably one used in the production of polyurethane resin, and more preferably one or more catalysts selected from the group consisting of tertiary amine compounds that do not contain hydroxyl groups and metal catalysts. The tertiary amine compounds that do not contain the above-mentioned hydroxyl group are preferably one or more selected from the group consisting of, for example, diazabicycloundecene, triethylamine, tripropylamine, tributylamine, hexadecyldimethylamine, N-methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, diethyltriamine, 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. The above metal catalyst is preferably one or more selected from the group consisting of, for example, stanus octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker captide, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin marker captide, dioctyltin thiocarboxylate, lead octyolate, potassium acetate, and potassium octyolate. These decomposition catalysts can be used individually or in combination of two or more.

[0022] The amount of decomposition catalyst added is not particularly limited. From the viewpoint of sufficiently decomposing the polyurethane foam to be decomposed, the amount of decomposition catalyst added is preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the polyurethane foam to be decomposed. The amount of decomposition catalyst added is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, taking into consideration the effect on the reactivity and physical properties when the decomposed product is reused as a raw material for recycled polyurethane foam, etc. From these viewpoints, the amount of decomposition catalyst added is preferably 0.05 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 5 parts by mass or less.

[0023] (4) Decomposition conditions for decomposed polyurethane foam The decomposition conditions for the polyurethane foam to be decomposed are not particularly limited. From the viewpoint of improving the decomposition rate, it is preferable to heat the polyurethane foam together with a decomposition agent. When heating the polyurethane foam together with a decomposition agent, it is preferable to stir the mixture of the polyurethane foam and the decomposition agent.

[0024] The decomposition treatment temperature is preferably 80°C to 300°C, more preferably 100°C to 270°C, and even more preferably 150°C to 250°C, in order to improve the decomposition rate while suppressing the decomposition of polyols derived from the decomposed product. The decomposition time may be, for example, 10 minutes to 24 hours, or 30 minutes to 10 hours. The end point of the decomposition time may be set appropriately while checking the progress of decomposition of the polyurethane resin, depending on the size of the polyurethane foam to be decomposed, whether or not it is stirred, etc. Also, for example, when decomposing the polyurethane foam to be decomposed at room temperature (e.g., 25°C) or below 80°C, the decomposition time may be set to be longer than 24 hours.

[0025] In this disclosure, the treated product obtained by decomposing a polyurethane foam with a decomposing agent is referred to as the decomposed product. The state of the decomposed product is not particularly limited. Preferably, the decomposed product is separated into two phases: a phase containing a polyol derived from the decomposed product (hereinafter also referred to as the polyol phase) and a phase containing an amine compound derived from the decomposed product (for example, an amine compound derived from the raw material isocyanate) (hereinafter also referred to as the amine phase). When the decomposing agent contains an amine compound, the decomposed product can be suitably obtained in a state separated into two phases: the polyol phase and the amine phase. The polyol phase is usually obtained as a liquid phase. The amine phase can be obtained as a liquid, semi-solid, or solid phase depending on the type and amount of the decomposing agent. The decomposed product may further contain solid components that were contained in the polyurethane foam. The solid components that were contained in the polyurethane foam include, for example, components derived from polymer polyols, fillers, flame retardants such as phosphorus-based flame retardants and halogen-based flame retardants. The polymer polyol-derived components are polymers such as styrene and acrylonitrile.

[0026] When the decomposition product separates into two phases, the polyol phase is of higher purity compared to the decomposition product in a single phase where the polyol phase and amine phase are not separated. Nevertheless, some amine compounds produced as by-products during decomposition remain dissolved in the polyol phase. According to the technology of this disclosure, in the second step described later, the amine compounds dissolved in the polyol phase can be removed as precipitates such as amide compounds by reacting them with an acid. As a result, the amount of amine compounds dissolved in the polyol phase can be reduced, and an even higher purity polyol can be obtained from the polyol phase.

[0027] The polyol composition may contain other components as long as it contains polyols derived from the decomposition treatment. For example, the polyol composition may contain amine compounds derived from the raw material isocyanate. In addition, the polyol composition may contain amine compounds added as decomposition agents, polymers such as styrene and acrylonitrile that were contained in the decomposed polyurethane foam, flame retardants, catalysts, and other additives.

[0028] The first step may involve obtaining the entire decomposition product as a polyol composition. When obtaining the entire decomposition product as a polyol composition, the step of recovering polyols derived from the decomposition product can be omitted. Alternatively, in the step of obtaining the polyol composition, only the polyol phase of the decomposition product may be obtained as the polyol composition after the phase separation of the decomposition product has occurred.

[0029] 1-2 2nd process The second step is to add a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition. (1) Carboxylic acid compounds The carboxylic acid compound is not particularly limited as long as it does not cause foaming defects or other problems during the manufacture of recycled polyurethane foam. The carboxylic acid compound can be used alone or in a mixture of two or more types. Organic carboxylic acid compounds are preferred. It is also preferable that the carboxylic acid compound is a carboxylic acid having two or more carboxyl groups and / or its anhydride. Hereinafter, carboxylic acids having two or more carboxyl groups and / or their anhydrides will also be simply referred to as polycarboxylic acids and / or their anhydrides. The number of carboxyl groups in the polycarboxylic acid and / or its anhydride is preferably 2 or more and 4 or less, and more preferably 2 or 3. In this disclosure, "carboxyl groups of the polycarboxylic acid anhydride" refers to carboxyl groups derived from the acid anhydride group of the anhydride. Polycarboxylic acids and / or their anhydrides may be aromatic carboxylic acids or aliphatic carboxylic acids. The number of carbon atoms in polycarboxylic acids and / or their anhydrides is preferably 2 to 20, more preferably 2 to 12, and even more preferably 3 to 10. The number of carbon atoms as used herein includes the number of carbon atoms in the carboxyl group. 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. The upper limit of the above boiling point or decomposition temperature is not particularly limited, and is usually 500°C or lower. The melting point of polycarboxylic acids and / or their anhydrides at 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 above melting point is not particularly limited, and is usually 20°C or higher, but may be 50°C or higher, 80°C or higher, or 95°C or higher.

[0030] The polycarboxylic acid and / or its anhydride is preferably one or more selected from the group consisting of succinic anhydride, o-phthalic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, dipropylmalonic acid, maleic acid, trans-3-hexanoic acid, itaconic acid, malic acid, tartaric acid, citric acid, trans-aconitic acid, 2,3-pyridinecarboxylic acid, maleic anhydride, phthalic anhydride, and trimellitic anhydride. The polycarboxylic acid and / or its anhydride is also preferably a boiling point or decomposition temperature of 150°C or higher.

[0031] The amount of carboxylic acid compounds added is not particularly limited, as long as it does not cause foaming defects or other problems during the manufacture of recycled polyurethane foam. When the carboxylic acid compound is a polycarboxylic acid and / or its anhydride, the amount of carboxylic acid compounds added should be as follows. In other words, in the method for producing recycled polyurethane foam, it is preferable to add a polycarboxylic acid and / or its anhydride to the polyol composition such that the ratio of the molar amounts of carboxyl groups and carboxyl groups derived from the acid anhydride groups of the anhydride to the molar amount of amino groups in the polyol composition is 0.5 or more and 1.5 or less. More preferably, the ratio of the molar amounts of carboxyl groups and carboxyl groups derived from the acid anhydride groups of the anhydride to the molar amount of amino groups in the polyol composition is 0.6 or more and 1.35 or less. When the above molar ratio is greater than or equal to the above lower limit, the amine compound in the polyol composition can be suitably precipitated as a precipitate. Furthermore, when the above molar ratio is less than or equal to the above upper limit, the amount of carboxylic acid compounds mixed into the acid-treated polyol composition when the acid-treated polyol composition is recovered can be suitably reduced.

[0032] The molar amount of amino groups in a polyol composition can be calculated by measuring the total amine value in accordance with JIS K 1557-7. If the polyol composition is separated into a polyol phase and a different phase, the molar amount of amino groups in the polyol composition can be calculated by measuring the total amine value of both the polyol phase and the different phase in accordance with JIS K 1557-7, and then calculating the weighted average from the mass ratio of the polyol phase and the different phase.

[0033] The total amine value of the polyol phase is not particularly limited. For example, the total amine value of the polyol phase may be between 30 mg KOH / g and 300 mg KOH / g, between 40 mg KOH / g and 200 mg KOH / g, or between 60 mg KOH / g and 180 mg KOH / g. The total amine value of the phase other than the polyol phase is not particularly limited. For example, the total amine value of the phase other than the polyol phase may be between 80 mg KOH / g and 500 mg KOH / g, between 100 mg KOH / g and 400 mg KOH / g, or between 150 mg KOH / g and 350 mg KOH / g. The mass ratio of the polyol phase to the other phase (polyol phase:other phase) is not particularly limited. For example, the polyol phase:other phase ratio could be 10:90-90:10, 25:75-80:20, or 30:70-70:30.

[0034] The molar amount of carboxyl groups can be calculated as the sum of the value obtained by multiplying the molar amount of the added polycarboxylic acid by the number of carboxyl groups, and the value obtained by multiplying the molar amount of the added acid anhydride by twice the number of acid anhydride groups.

[0035] (2) Conditions for adding carboxylic acid compounds The second step preferably involves adding a carboxylic acid compound to the polyol composition and heating it. The heating temperature is not particularly limited. From the viewpoint of precipitate formation, the heating temperature should be 150°C or higher, but may be 160°C or higher, 170°C or higher, or 180°C or higher. The upper limit of the heating temperature is not particularly limited. From the viewpoint of suppressing vaporization and decomposition of the carboxylic acid compound, the upper limit of the heating temperature should be, for example, 280°C or lower, but may be 260°C or lower, 240°C or lower, or 220°C or lower.

[0036] The above heating may be carried out using the residual heat generated during the decomposition process of the polyurethane foam to be decomposed. For example, by adding a carboxylic acid compound before the heated decomposition material cools to room temperature and then performing the above heating, the heating and cooling time during the addition of the carboxylic acid compound can be shortened, and energy such as electricity can be reduced.

[0037] The heating time may be, for example, 10 minutes to 24 hours, or 30 minutes to 10 hours. The end point of the heating time may be set as appropriate, while confirming that the total amine value and / or hydroxyl value of the polyol composition has been sufficiently reduced.

[0038] In the second step, the mixture of the polyol composition and the polycarboxylic acid and / or its anhydride may be stirred during the heating process described above. Since dehydration condensation occurs when a polycarboxylic acid and / or its anhydride is added and heated, the second step may involve supplying a dry gas during the heating process. For example, the polyol composition and the polycarboxylic acid and / or its anhydride may be placed in a container and heated, and a dry gas may be supplied into the container from an external gas source. Dry nitrogen is a suitable dry gas, for example. Furthermore, the removal of moisture may be accelerated by reducing the pressure. There are no particular restrictions on the degree of vacuum during this reduction, but for example, 10 4 Pa or less is preferable, 10 3 Pa or less is more preferable, 10 2 Pa or lower is even more preferable.

[0039] In this disclosure, a product obtained by adding a carboxylic acid compound to a polyol composition is referred to as an acid-added product. The acid-added product may, for example, contain a polyol phase containing polyols derived from the decomposition product and a phase of solid matter separated from the polyol phase. Such solid matter can be removed, for example, by filtration. The removed solid matter may be discarded or used separately as a filler or the like. If the solid matter is not removed, the solid matter may be used as is, or crushed to a predetermined size, as a filler for recycled polyurethane foam.

[0040] In the second step, an acid-treated polyol composition may be obtained by removing solid matter from the acid-added product as a raw material for the third step, or the entire acid-added product may be obtained as an acid-treated polyol composition.

[0041] (3) Components of the acid-treated polyol composition The acid-treated polyol composition may contain other components as long as it contains a polyol derived from the decomposition product. When a carboxylic acid compound is added to the above polyol composition, a reaction product between the amine compound derived from the decomposition product and the carboxylic acid compound may be produced. The type of reaction product can be appropriately controlled depending on the types of amine and carboxylic acid compounds, the heating temperature, etc. It is presumed that the reaction product is one or more selected from the group consisting of, for example, salts of the amine compound and the carboxylic acid compound, and amide compounds (including imide compounds) having a structure derived from the amine compound and / or the carboxylic acid compound.

[0042] The acid-treated polyol composition preferably contains a regenerated polyol with a number average molecular weight of 4000 or more and a component with a number average molecular weight of 1500 or less. The presence of a regenerated polyol with a number average molecular weight of 4000 or more and a component with a number average molecular weight of 1500 or less can be confirmed by analyzing the acid-treated polyol composition by gel permeation chromatography (GPC) to obtain the molecular weight distribution in terms of standard polyols. For example, in the molecular weight distribution in terms of standard polyols measured by gel permeation chromatography (GPC), the acid-treated polyol composition has a peak in the region of a number average molecular weight of 1500 or less.

[0043] Currently, we have not been able to identify any components with a number-average molecular weight of 1500 or less. These components are thought to be either components derived from the decomposed polyurethane foam, reaction products of components derived from the decomposed polyurethane foam and the decomposition agent, reaction products of components derived from the decomposed polyurethane foam and carboxylic acid compounds, or mixtures thereof.

[0044] This point will be explained in detail by comparing Examples 1, 3, and 4, and Example 5, which will be described later. The acid-treated polyol compositions of Examples 1, 3, and 4 showed peaks in the region of number average molecular weight between 100 and 200, and in the region of number average molecular weight between 800 and 1200, in the molecular weight distribution on a standard polyol basis measured by GPC. On the other hand, the acid-treated polyol composition of Example 5 showed a peak in the region of number average molecular weight between 100 and 200, but no peak in the region of number average molecular weight between 800 and 1200, in the molecular weight distribution on a standard polyol basis measured by GPC. The decomposed polyurethane foams of Examples 1, 3, and 4 were molded polyurethane foams, while the decomposed polyurethane foam of Example 5 was a slab polyurethane foam. Differences in the raw material components and manufacturing methods of the decomposed polyurethane foams may be related to the generation of components with a number average molecular weight of 1500 or less.

[0045] When recycled polyurethane foam was produced using the acid-treated polyol compositions of Examples 1, 3, and 4, the hardness of the recycled polyurethane foam was higher than that of the decomposed polyurethane foam in all examples. On the other hand, when recycled polyurethane foam was produced using the acid-treated polyol composition of Example 5, the hardness of the recycled polyurethane foam was lower than that of the decomposed polyurethane foam. The formulation of the recycled polyurethane foam was obtained by replacing a portion of the polyether polyols with a number average molecular weight of 4000 or more in the formulation of the decomposed polyurethane foam in the respective examples with the acid-treated polyol composition.

[0046] These results suggest that the acid-treated polyol composition of this embodiment improves the hardness of recycled polyurethane foam compared to virgin polyether polyols. Although the reason is not clear, it is possible that components with a number-average molecular weight of 1500 or less, which are not present in virgin polyether polyols, contribute to the improvement in the hardness of recycled polyurethane foam.

[0047] Furthermore, in the acid-treated polyol compositions of Examples 1, 3, and 4, the recycled polyols with a number average molecular weight of 4000 or more showed a molecular weight distribution similar to that of polyether polyols with a number average molecular weight of 4000 or more that were used as raw materials for decomposition-prone polyurethane foam. It is presumed that the recycled polyols with a number average molecular weight of 4000 or more were obtained as recycled polyols from the raw material polyols of the decomposition-prone polyurethane foam.

[0048] (4) pH, total amine value, and hydroxyl value of the acid-treated polyol composition The pH of the acid-treated polyol composition is not particularly limited. The pH of the acid-treated polyol composition is preferably 5 to 10, more preferably 6 to 10, and even more preferably 7 to 10. The pH of the acid-treated polyol composition can be measured in accordance with JIS K 1557-5.

[0049] The total amine value of the acid-treated polyol composition is not particularly limited. Preferably, the total amine value of the acid-treated polyol composition is less than 45 mg KOH / g, more preferably less than 30 mg KOH / g, and even more preferably 20 mg KOH / g or less. The lower limit of the total amine value of the acid-treated polyol composition is not particularly limited. The total amine value of the acid-treated polyol composition is 0 mg KOH / g or more, and usually 1 mg KOH / g or more. The total amine value of the acid-treated polyol composition can be measured in accordance with JIS K 1557-7.

[0050] The hydroxyl value of the acid-treated polyol composition is not particularly limited. For example, the hydroxyl value of the acid-treated polyol composition may be 10 mg KOH / g or more and 200 mg KOH / g or less, 20 mg KOH / g or more and 150 mg KOH / g or less, or 25 mg KOH / g or more and 100 mg KOH / g or less. The hydroxyl value of the acid-treated polyol composition can be measured in accordance with JIS K 1557-1.

[0051] Furthermore, the above-mentioned pH, total amine value, and hydroxyl value can be controlled by adjusting the amount of carboxylic acid compound added.

[0052] 1-3 3rd process The third step is a process for producing recycled polyurethane foam using an acid-treated polyol composition as a raw material. For example, the third step involves preparing a composition for recycled polyurethane foam containing an acid-treated polyol composition and polyisocyanate, and then producing recycled polyurethane foam by mold foaming.

[0053] The amount of acid-treated polyol composition is not particularly limited. From the viewpoint of recyclability, the amount of acid-treated polyol composition is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, when the total amount of polyol contained in the recycled polyurethane foam composition is 100 parts by mass. From the viewpoint of ensuring various physical properties, the amount of acid-treated polyol composition is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less. From these viewpoints, the amount of acid-treated polyol composition is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 70 parts by mass or less, and even more preferably 30 parts by mass or more and 50 parts by mass or less. Note that if the acid-treated polyol composition contains solid matter, the amount of acid-treated polyol composition mentioned above refers to the amount of the liquid phase portion excluding the solid matter of the acid-treated polyol composition.

[0054] (1) Polyisocyanate The polyisocyanate is not particularly limited. At least one polyisocyanate selected from the group consisting of aromatic isocyanates, alicyclic isocyanates, and aliphatic isocyanates is preferably used. One or more aliphatic isocyanates and one or more aromatic isocyanates may be used in combination. The polyisocyanate may be a bifunctional polyisocyanate having two isocyanate groups in one molecule, or a trifunctional or more polyisocyanate having three or more isocyanate groups in one molecule, and may be used alone or in combination of several.

[0055] For example, difunctional polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylenediisocyanate, and 3,3'-dimethoxy-4,4'-biphenylenediisocyanate. Examples include aromatic isocyanates such as phenylenediisocyanate, alicyclic isocyanates such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate, and aliphatic isocyanates such as butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylenediisocyanate, methylene diisocyanate, and lysine isocyanate. Furthermore, examples of polyisocyanates with three or more functions include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate, triphenylmethane-4,4',4"-triisocyanate, polymeric MDI, etc. In addition, urethane prepolymers, carbodiimide-modified isocyanates, isocyanurate-modified isocyanates, and burette-modified isocyanates can also be used.

[0056] The amount of polyisocyanate blended is not particularly limited. The isocyanate index is preferably 70 to 120, and more preferably 80 to 110. The isocyanate index (NCO-index) is the value obtained by multiplying the ratio of the number of moles of isocyanate groups of the isocyanate compound to the total number of moles of hydroxyl groups contained in the polyurethane resin composition by 100, and is calculated as [(equivalent amount of isocyanate groups of the isocyanate compound / total equivalent amount of hydroxyl groups in the composition) × 100].

[0057] (2) Recycled polyurethane foam The above acid-treated polyol composition exhibits excellent foaming properties and is therefore suitable for the production of various recycled polyurethane foams. This disclosure is also effective, for example, when the decompositionable polyurethane foam is a molded polyurethane foam using a polyol with a number average molecular weight of 4000 or more as a raw material, and the recycled polyurethane foam is also a molded polyurethane foam.

[0058] The applications of recycled polyurethane foam are not particularly limited. Recycled polyurethane foam is suitable for use as automotive cushioning. Currently, chemical recycling of automotive cushioning is difficult, and in reality, much of used automotive cushioning is discarded. In recent years, in order to achieve the Sustainable Development Goals, there has been a growing demand for the use of a certain percentage of recycled materials in plastics used in the manufacture of automobiles, in particular for the use of recycled materials from scrapped vehicle parts. From this perspective, this disclosure is particularly suitable when the decomposable polyurethane foam is automotive polyurethane foam and the recycled polyurethane foam is also automotive polyurethane foam.

[0059] The physical properties of recycled polyurethane foam can be appropriately set according to the application and other factors. It is preferable that the recycled polyurethane foam be a flexible polyurethane foam. However, the physical properties of recycled polyurethane foam are not particularly limited.

[0060] The core density of the recycled polyurethane foam (conforming to JIS K7222:2005) is 0.015 / cm 3 or more and 0.100 g / cm 3 or less, preferably 0.040 g / cm 3 or more and 0.080 g / cm 3 or less, more preferably 0.050 g / cm 3 or more and 0.070 g / cm 3 or less, even more preferably.

[0061] The hardness of the recycled polyurethane foam (JIS K6400-2:2012 6.7 D method, 25% ILD) is preferably 30 N - 600 N, more preferably 150 N - 500 N, and even more preferably 200 N - 400 N. The above hardness is the value measured using a pressure plate with a diameter of 200 mm.

[0062] The above acid-treated polyol composition can exhibit an effect of improving the hardness of the recycled polyurethane foam. In the present disclosure, it is also preferable that the 25% ILD of the recycled molded polyurethane foam is not less than the 25% ILD of the decomposed molded polyurethane foam.

[0063] 2. Effects of the present embodiment The present embodiment has been developed through the following process and can provide a novel technique for obtaining a recycled polyurethane foam.

[0064] Conventionally, although there are reports that rigid urethane foams and flexible urethane foams can be chemically decomposed and returned to their original raw materials, for example, there is no report that a urethane foam used for an automobile seat cushion can be chemically decomposed and recycled again into a urethane foam used for an automobile seat cushion.

[0065] The inventors of this invention first investigated the use of recycled polyol as a raw material for automotive seat cushions by amine-decomposing polyurethane foam, which is used for automotive seat cushions, to produce and separate recycled polyol and residue, and then using the obtained recycled polyol as a raw material for automotive seat cushions. However, when this recycled polyol was used as a raw material as is, foaming defects occurred, and it was not possible to obtain polyurethane foam with sufficient physical properties for automotive seat cushions. The inventors of this invention diligently investigated and found that by adding a carboxylic acid compound after the decomposition of the polyurethane foam to be decomposed, and adjusting the pH, total amine value, and hydroxyl value of the recycled polyol, it was possible to obtain polyurethane foam with sufficient physical properties for automotive seat cushions without causing foaming defects, and thus developed the technology of this disclosure.

[0066] According to this embodiment, by performing the second step described above, the amount of amino groups contained in the acid-treated polyol composition can be reduced, thereby suppressing foaming defects during the manufacture of recycled polyurethane foam. Furthermore, when decomposing polyurethane foam using aromatic isocyanates as raw materials, harmful aromatic amine compounds may be generated. By subjecting the acid-treated polyol composition that has undergone the second step to the third step, various operations can be performed with reduced aromatic amine compounds, thereby improving safety during operation.

[0067] According to this embodiment, even polyurethane foam products that were previously difficult to chemically recycle can be recycled into products similar to the original products. For example, even if the decomposable polyurethane foam is for automotive cushions, it is possible to manufacture automotive cushions using recycled polyurethane foam. The automotive cushions made from decomposable polyurethane foam and / or recycled polyurethane foam are not particularly limited. As an example of an automotive cushion, the seat pad 10 of a vehicle seat shown in Figure 1 is provided. The decomposable polyurethane foam may be the polyurethane foam for the main part 11A and / or the side part 11B of the seat cushion 11. The decomposable polyurethane foam may be the polyurethane foam for the main part 13A and / or the side part 13B of the seat back 13. Furthermore, the recycled polyurethane foam may be the polyurethane foam for the main part 11A and / or the side part 11B of the seat cushion 11. The recycled polyurethane foam may be the polyurethane foam for the main part 13A and / or the side part 13B of the seat back 13.

[0068] The acid-treated polyol composition of this embodiment can suitably ensure the hardness of recycled polyurethane foam. Therefore, the acid-treated polyol composition of this embodiment can be used, for example, as a substitute for polymer polyols, which are hardness-imparting raw materials for recycled polyurethane foam. [Examples]

[0069] 1. Manufacturing of biodegradable polyurethane foam 1-1 Examples 1-4, Comparative Example 1 Polyurethane foam compositions (liquid A and liquid B) were prepared in the proportions shown in Table 1, and a decomposable polyurethane foam [1] was produced by mold foaming. In other words, the decomposable polyurethane foam [1] is a molded polyurethane foam. The core density of the obtained decomposable polyurethane foam [1] was measured in accordance with JIS K7222:2005. The hardness (25% ILD) of the obtained polyurethane foam was also measured in accordance with JIS K6400-2:2012 6.7 Method D. The measured core density and hardness are shown together in Table 1.

[0070] Details of each ingredient are as follows: • Polyol A: Polyether polyol, number average molecular weight 5000, number of functional groups 3, hydroxyl value 33 mgKOH / g, product name Polyol FA703V, manufactured by Sanyo Chemical Industries, Ltd. • Polyol B: Polyether polyol, number average molecular weight 7000, number of functional groups 3, hydroxyl value 25 mg KOH / g, product name Actcol EP-902N, manufactured by Mitsui Chemicals, Inc. • Polymer Polyol 1: Product Name: Polyol FM-5704, manufactured by Sanyo Chemical Industries, Ltd. • Crosslinking agent 1: Glycerine, manufactured by Chuo Kasei Co., Ltd. • Crosslinking agent 2: Product name DEA-80, manufactured by Mitsui Chemicals, Inc. • Catalyst 1: Product name DABCO BL19, manufactured by EVONIK. • Catalyst 2: Product name DABCO 33LSI, manufactured by EVONIK. • Foam stabilizer 1: Product name NiAX L-3184J, manufactured by MOMENTIVE Co., Ltd. • Foam stabilizer 2: Product name TEGOSTAB B 8738 LF2, manufactured by EVONIK. • Foaming agent: Water • Isocyanate 1: Product name Cosmonate™-20, manufactured by Mitsui Chemicals, NCO%: 44.8% Polyol A, Polyol B, and Polymer Polyol 1 correspond to "polyols with a number average molecular weight of 4000 or more."

[0071] [Table 1]

[0072] 1-2 Example 5 Polyurethane foam compositions (liquid A and liquid B) were prepared in the proportions shown in Table 2, and a decomposable polyurethane foam [2] was produced by slab foaming. That is, the decomposable polyurethane foam [2] is a slab polyurethane foam. The core density of the obtained decomposable polyurethane foam [2] was measured in accordance with JIS K7222:2005. The hardness (25% ILD) of the obtained polyurethane foam was also measured in accordance with JIS K6400-2:2012 6.7 Method D. The measured core density and hardness are shown together in Table 2.

[0073] Details of each ingredient are as follows: • Polyol C: Polyether polyol, number average molecular weight 3000, number of functional groups 3, hydroxyl value 56.1 mgKOH / g, product name Sannix GP-3050NS, manufactured by Sanyo Chemical Industries, Ltd. • Polymer polyol 2: Acrylonitrile-styrene graft polymer polyol, product name: AGG Exenol 941 • Amine catalyst: Product name: DABCO 33LSI, manufactured by EVONIK. • Foam stabilizer 3: Silicone foam stabilizer, product name: L-595, manufactured by Momentive. • Tin catalyst: Stannous octylate, Product name: MRH-110, Manufactured by Johoku Chemical Industry Co., Ltd. • Foaming agent: Water • Isocyanate 2: Tolylene diisocyanate, product name Coronate T-80, manufactured by Tosoh Corporation, NCO%: 48.2%

[0074] [Table 2]

[0075] 1-3 Example 6 Polyurethane foam compositions (liquid A and liquid B) were prepared in the proportions shown in Table 3, and decomposable polyurethane foam [3], decomposable polyurethane foam [4], and decomposable polyurethane foam [5] were produced by mold foaming. That is, decomposable polyurethane foams [3]-[5] are molded polyurethane foams. Decomposable polyurethane foam [3] has properties suitable for polyurethane foam for the main part of a seat cushion. Decomposable polyurethane foam [4] has properties suitable for polyurethane foam for the main part of a seat back. Decomposable polyurethane foam [5] has properties suitable for polyurethane foam for the side parts of a seat cushion and seat back. Each polyurethane foam composition (liquid A and liquid B) has a target density of 45 kg / m³. 3 The mixture was then placed into the mold. The details of each ingredient are the same as in "1-1 Examples 1-4, Comparative Example 1".

[0076] [Table 3]

[0077] 2. Step to obtain the polyol composition (Step 1) 2-1 Examples 1-3 In a 3 L separable flask, 1 kg (100 parts by mass) of polyurethane foam to be decomposed [1] was mixed with the decomposition agent and decomposition catalyst in the mass ratios shown in Table 4, and heated at 180°C for 6 hours with stirring. The resulting decomposition product was separated into a liquid phase (polyol phase) and a phase containing solid matter. This entire decomposition product was subjected to the process (second step) to obtain the acid-treated polyol composition described later, as a polyol composition. Details of the decomposition agent and decomposition catalyst are as follows. • Decomposing agent in Examples 1-3: 3,3'-diaminodipropylamine • Decomposition catalyst for Examples 1-3: Diazabicycloundecene (DBU)

[0078] 2-2 Example 4 In a 3 L separable flask, 1 kg (100 parts by mass) of polyurethane foam to be decomposed [1] was mixed with the decomposition agent and decomposition catalyst in the mass ratios shown in Table 4, and heated at 180°C for 6 hours with stirring. The resulting decomposition product was separated into a liquid phase (polyol phase) and a phase containing solid matter. This entire decomposition product was subjected to the process (second step) to obtain the acid-treated polyol composition described later, as a polyol composition. Details of the decomposition agent and decomposition catalyst are as follows. • Decomposing agent in Example 4: 2-(2-aminoethoxy)ethanol • Decomposition catalyst for Example 4: Diazabicycloundecene (DBU)

[0079] 2-3 Example 5 In a 3 L separable flask, the decomposing agent was added to 1 kg (100 parts by mass) of the polyurethane foam to be decomposed [2] in the mass ratio shown in Table 4, and the mixture was heated at 180°C for 6 hours with stirring. The resulting decomposed product was separated into a liquid phase (polyol phase) and a phase containing solid matter. The entire decomposed product was subjected to the process (second step) to obtain the acid-treated polyol composition described later, as a polyol composition. Details of the decomposition agent are as follows: • Decomposing agent in Example 5: 3,3'-diamino-N-methyldipropylamine

[0080] 2-4 Example 6 In a 3 L separable flask, 0.3333 kg (33.33 parts by mass) each of the polyurethane foam to be decomposed [3], [4], and [5], totaling 1 kg (100 parts by mass), were mixed with the decomposition agent and decomposition catalyst in the mass ratios shown in Table 5, and the mixture was heated at 180°C for 6 hours with stirring. The resulting decomposition product was separated into a liquid phase (polyol phase) and a phase containing solid matter. The entire decomposition product was subjected to the process (second step) to obtain the acid-treated polyol composition described later, as a polyol composition. Details of the decomposition agent and decomposition catalyst are as follows. • Decomposing agent in Example 6: 2-(2-aminoethoxy)ethanol • Decomposition catalyst for Example 6: Diazabicycloundecene (DBU)

[0081] 2-5 Comparative Example 1 In a 3L separable flask, the decomposing agent was added to 1 kg (100 parts by mass) of the polyurethane foam to be decomposed [1] in the mass ratio shown in Table 5, and the mixture was heated at 180°C for 6 hours with stirring. The resulting decomposed product was separated into a liquid phase (polyol phase) and a phase containing solid matter. The solid matter was removed from this decomposed product using a 40-mesh stainless steel mesh to obtain the liquid phase. This liquid phase was then subjected to the process of manufacturing recycled polyurethane foam (third step) without going through the process of obtaining the acid-treated polyol composition (second step). Details of the decomposition agent are as follows: • Decomposing agent in Comparative Example 1: 3,3'-diaminodipropylamine

[0082] [Table 4]

[0083] [Table 5]

[0084] 3. Step to obtain an acid-treated polyol composition (Step 2) A carboxylic acid compound was added to the obtained polyol composition to obtain an acid-treated polyol composition. Details of the carboxylic acid compounds are as follows: • Carboxylic acid compounds in Examples 1, 2, 4, and 5: Succinic anhydride • Carboxylic acid compound in Example 3: o-phthalic acid • Carboxylic acid compound of Example 6: succinic acid

[0085] Specifically, the carboxylic acid compounds listed in Tables 4 and 5 were added to a 3 L separable flask after the process of obtaining the polyol composition (first step), and the mixture was heated at 180°C for 3 hours. The amount of carboxylic acid compound added was calculated based on the formula: "molar amount of carboxyl groups in the carboxylic acid compound / molar amount of amino groups in the polyol composition".

[0086] The molar amount of amino groups in the polyol composition was calculated as follows. First, the total amine value was measured for both the liquid phase (polyol phase) and the phases other than the polyol phase of the obtained polyol composition, in accordance with JIS K 1557-7. In addition, the mass percentage (mass%) of the polyol phase and the mass percentage (mass%) of the phases other than the polyol phase were calculated, assuming the entire decomposition product was 100% by mass. The total amine value of the entire polyol composition was calculated based on the following formula 1. Total amine value of polyol composition = Total amine value of the polyol phase × Mass ratio of the polyol phase + Total amine value of the phase other than the polyol phase × Mass ratio of the phase other than the polyol phase ... (Equation 1)

[0087] The molar amount of carboxyl groups in carboxylic acid compounds was calculated by multiplying the molar amount of the added carboxylic acid compound by the number of carboxyl groups, or by multiplying the molar amount of the added acid anhydride by twice the number of acid anhydride groups. For example, the molar amount of carboxyl groups in 1 mole of succinic anhydride was assumed to be 2 moles.

[0088] For example, in Examples 1 and 2, the ratio of "moles of carboxyl groups in the carboxylic acid compound / molars of amino groups in the polyol composition" was 1.33. In Example 3, the ratio of "moles of carboxyl groups in the carboxylic acid compound / molars of amino groups in the polyol composition" was 0.80.

[0089] The resulting acid-treated material was separated into a liquid phase (polyol phase) and a phase containing solid matter. The solid matter was removed from this acid-treated material using a 40-mesh stainless steel mesh to obtain the liquid phase. This liquid phase was used as the acid-treated polyol composition in the process of manufacturing recycled polyurethane foam (third step).

[0090] 4. Evaluation of acid-treated polyol compositions 4-1. pH evaluation The pH of the acid-added polyol compositions of Examples 1 to 6 was calculated based on JIS K 1557-5. Also, the pH of the liquid phase of Comparative Example 1 was calculated based on JIS K 1557-5. The pH was evaluated according to the following criteria. The results are shown together in Tables 4 and 5. "A": pH is 7 or more and 10 or less "B": pH is 5 or more and less than 7 "C": pH is less than 5 or greater than 10

[0091] 4-2. Evaluation of Hydroxyl Value The hydroxyl values of the acid-added polyol compositions of Examples 1 to 6 were calculated based on JIS K 1557-1. Also, the hydroxyl value of the liquid phase of Comparative Example 1 was calculated based on JIS K 1557-1. The results are shown together in Tables 4 and 5.

[0092] 4-3. Evaluation of Total Amine Value The total amine values of the acid-added polyol compositions of Examples 1 to 6 were calculated based on JIS K 1557-7. Also, the total amine value of the liquid phase of Comparative Example 1 was calculated based on JIS K 1557-7. The total amine value was evaluated according to the following criteria. The results are shown together in Tables 4 and 5. "A": Total amine value is less than 30 mgKOH / g "B": Total amine value is 30 mgKOH / g or more and less than 45 mgKOH / g "C": Total amine value is 45 mgKOH / g or more

[0093] 4-4 GPC Analysis The acid-treated polyol compositions of Examples 1, 3, 4, and 5 were analyzed by gel permeation chromatography (GPC). The measurement conditions for GPC are as follows. <Measurement Conditions for GPC> Apparatus: "EXTREMA" [manufactured by Nippon Bunko K.K.] Solvent: THF Standard Substance: Polyol Detector: RI Sample Concentration: 2% Column stationary phase: The columns shown below are used in conjunction with each other. Each column has a length of 150 mm and a diameter of 6 mm. Shodex KF-603 (Target molecular weight range: 1,000-50,000, Exclusion limit molecular weight: 70,000) Shodex KF-602.5 (Target molecular weight range: 300-8,000, Exclusion limit molecular weight: 20,000) Shodex KF-602 (Target molecular weight range: 300-3,000, Exclusion limit molecular weight: 5,000) Shodex KF-601 (Target molecular weight range: 100-700, Exclusion limit molecular weight: 1,500) Column temperature: 40℃

[0094] GPC analysis revealed that the acid-treated polyol compositions of Examples 1, 3, 4, and 6 contained regenerated polyols with a number average molecular weight of 4000 or more, and components with a number average molecular weight of 1500 or less. The results are shown in Tables 4 and 5. In Tables 4 and 5, "GPC: Molecular Weight 5000 Percentage" represents the area percentage of regenerated polyols with a peak around a number average molecular weight of 5000. Regenerated polyols with a peak around a number average molecular weight of 5000 correspond to regenerated polyols with a number average molecular weight of 4000 or more. "GPC: Molecular Weight 1000 Percentage" represents the area percentage of components with a peak around a number average molecular weight of 1000, and "GPC: Molecular Weight 100-200 Percentage" represents the area percentage of components with a peak in the number average molecular weight range of 100-200. Components with a peak around a number average molecular weight of 1000 and components with a peak in the number average molecular weight range of 100-200 correspond to components with a number average molecular weight of 1500 or less.

[0095] Table 6 shows the results of the GPC analysis for Examples 1, 3, 4, and 5. In the molecular weight distribution of Example 1, there was a peak for a regenerated polyol with a number average molecular weight of 4626 (area proportion 85%), a peak for a number average molecular weight of 1082 (area proportion 5%), and a peak for a number average molecular weight of 100-200 (area proportion 10%). In the molecular weight distribution of Example 3, there was a peak for a regenerated polyol with a number average molecular weight of 4537 (area proportion 75%), a peak for a number average molecular weight of 1015 (area proportion 5%), and a peak for a number average molecular weight of 100-200 (area proportion 20%). In the molecular weight distribution of Example 4, there was a peak for a regenerated polyol with a number average molecular weight of 4492 (area percentage 90%), a peak for a number average molecular weight of 1046 (area percentage 5%), and a peak for a number average molecular weight of 100-200 (area percentage 5%). Furthermore, in the molecular weight distribution of Example 5, there was a peak for regenerated polyol with a number average molecular weight of 2480 (area proportion 92%) and a peak for polyol with a number average molecular weight of 100-200 (area proportion 7%).

[0096] [Table 6]

[0097] 5. Process for manufacturing recycled polyurethane foam (Third process) 5-1 Examples 1, 3, and 4 Polyurethane foam compositions (liquid A and liquid B) were prepared according to the formulations listed in Table 7 [1], and recycled polyurethane foam was produced by mold foaming. In other words, Examples 1, 3, and 4 are molded polyurethane foams. In Examples 1, 3, and 4, the entire amount of polyol A (polyether polyol) in the raw materials of the decomposable polyurethane foam was replaced with an acid-treated polyol composition. For details of the raw materials other than the acid-treated polyol composition, the explanation in "1-1 Examples 1-4, Comparative Example 1" applies as is.

[0098] 5-2 Example 2 A polyurethane foam composition (liquid A and liquid B) was prepared using the formulations listed in Table 7 [2], and recycled polyurethane foam was produced by mold foaming. In other words, Example 2 is a molded polyurethane foam. In Example 2, the entire amount of polyol A (polyether polyol) in the raw materials of the decomposable polyurethane foam was replaced with an acid-treated polyol composition, and the amount of polymer polyol 1 was reduced. Details of the raw materials other than the acid-treated polyol composition are as described in "1-1 Examples 1-4, Comparative Example 1".

[0099] 5-3 Example 5 Polyurethane foam compositions (solutions A and B) were prepared according to the formulations shown in Table 8, and recycled polyurethane foam was produced by slab foaming. In other words, Example 5 is a slab polyurethane foam. In Example 5, 30 parts by mass of polyol (polyether polyol) in the raw materials of the decomposable polyurethane foam were replaced with 30 parts by mass of acid-treated polyol composition. Details of the raw materials other than the acid-treated polyol composition are as described in "1-2 Example 5".

[0100] 5-4 Example 6 Polyurethane foam compositions (liquid A and liquid B) were prepared according to the formulations listed in Table 7 [4], and recycled polyurethane foam was produced by mold foaming. In other words, Example 6 is a molded polyurethane foam. Example 6 is a formulation in which the entire amount of polyol A (polyether polyol) and polyol A (polyether polyol) in the raw materials of the decomposable polyurethane foam [5] is replaced with an acid-treated polyol composition, and the proportion of components other than polyols is adjusted. The formulation of Example 6 is suitable for polyurethane foam for the side parts of seat cushions and seat backs. Details of the acid-treated polyol composition and raw materials other than crosslinking agent 3 below are as described in "1-1 Examples 1-4, Comparative Example 1". • Crosslinking agent 3: Product name IR94, manufactured by Mitsui Chemicals, Inc.

[0101] 5-5 Comparative Example 1 Comparative Example 1 was manufactured in the same manner as in Examples 1, 3, and 4, except that the liquid phase obtained in "2. Step to obtain the polyol composition (Step 1)" was used instead of the acid-treated polyol composition.

[0102] [Table 7]

[0103] [Table 8]

[0104] 6. Evaluation of recycled polyurethane foam 6-1 Foaming The foaming properties of recycled polyurethane foam were evaluated visually according to the following criteria. The results are shown in Tables 4 and 5. "A": Has good foaming properties and can be manufactured as a foam. "C": Poor foaming properties; cannot be manufactured as a foam.

[0105] 6-2 Density (Core Density) The skin layer was removed from the recycled polyurethane foam to prepare a sample for core density measurement. The core density of the obtained sample was measured in accordance with JIS K 7222:2005. Note that the density of Comparative Example 1 was not measured because recycled polyurethane foam could not be produced. The results are shown together in Tables 4 and 5, and are also summarized in Table 9 along with the core density of the polyurethane foam (blank) described later.

[0106] 6-3 Hardness (25%ILD) The hardness of the recycled polyurethane foam was measured in accordance with JIS K6400-2:2012 6.7 Method D. The hardness was evaluated in comparison with polyurethane foam without the acid-treated polyol composition (hereinafter also referred to as polyurethane foam (blank)) according to the following criteria. In Examples 1-4, the decomposed polyurethane foam [1] was used as the polyurethane foam (blank). In Example 5, the decomposed polyurethane foam [2] was used as the polyurethane foam (blank). In Example 6, since an acid-treated polyol composition was obtained using three types of decomposed polyurethane foams [3]-[5] with different hardnesses, the polyurethane foam composition (liquid A and liquid B) was prepared using the formulation [5] described in Table 7, and the polyurethane foam (blank) was manufactured by mold foaming. In Comparative Example 1, polyurethane foam could not be produced, so the hardness was not measured. The results are shown together in Tables 4 and 5, and are also summarized in Table 9 along with the hardness of the polyurethane foam (blank). "A": The hardness is greater than or equal to that of the polyurethane foam (blank) in the embodiment. "B": Less than the hardness of the polyurethane foam (blank) in this embodiment. "C": Unable to evaluate physical properties

[0107] [Table 9]

[0108] 6-4 Overall decision The overall evaluation of Examples 1-6 and Comparative Example 1 was conducted according to the following criteria. The results are shown in Tables 4 and 5. "A": The evaluation of pH, total amine value, effervescence, and hardness all received an "A" rating. "B": A "B" rating is given in one of the following evaluations: pH, total amine value, effervescence, or hardness; no "C" rating is given. "C": A "C" rating is given in one of the following evaluations: pH evaluation, total amine value evaluation, effervescence evaluation, or hardness evaluation.

[0109] 7.Results The manufacturing methods for recycled polyurethane foam in Examples 1-6 satisfy the following requirements (a)-(c). The manufacturing method for recycled polyurethane foam in Comparative Example 1 does not satisfy the following requirements (b) and (c). • Requirement (a): The process includes decomposing a polyurethane foam to be decomposed with a decomposing agent to obtain a polyol composition containing polyols derived from the decomposed product. Requirement (b): The requirement includes a step of adding a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition. Requirement (c): The process of producing recycled polyurethane foam using the acid-treated polyol composition as a raw material.

[0110] Examples 1-6 received an overall rating of "A" or "B". On the other hand, Comparative Example 1 received an overall rating of "C". It was found that Examples 1-6, which satisfy requirements (a)-(c), can reduce foaming defects in recycled polyurethane foam by including a step (second step) to obtain an acid-treated polyol composition.

[0111] Of Examples 1-6, Examples 1-4 and Example 6 further satisfy the following requirement (d). Requirement (d): The decomposable polyurethane foam is a molded polyurethane foam that uses a polyol with a number average molecular weight of 4000 or more as a raw material. The recycled polyurethane foam is a molded polyurethane foam.

[0112] Examples 1-4 and 6, which satisfy requirement (d), received an overall rating of "A". On the other hand, Example 5, which does not satisfy requirement (d), received an overall rating of "B". The technology of this disclosure, which satisfies requirements (a)-(c), was found to be suitable for recycling molded polyurethane foam.

[0113] 8. Effects of the Examples This embodiment provides a novel technique for obtaining recycled polyurethane foam.

[0114] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of this disclosure. [Explanation of Symbols]

[0115] 10...Seat pad 11... Seat cushion 11A...Main section 11B...Side section 13... Seat back 13A...Main section 13B...Side section

Claims

1. A process of decomposing a polyurethane foam to be decomposed with a decomposition agent to obtain a polyol composition containing polyols derived from the decomposition treatment product, A step of adding a carboxylic acid compound to the polyol composition to obtain an acid-treated polyol composition, A method for producing recycled polyurethane foam, comprising the step of producing recycled polyurethane foam using the acid-treated polyol composition as a raw material.

2. A method for producing recycled polyurethane foam according to claim 1, wherein the decomposition agent is an amine compound.

3. The aforementioned decomposable polyurethane foam is a molded polyurethane foam, which uses a polyol with a number average molecular weight of 4000 or more as a raw material. The method for producing recycled polyurethane foam according to claim 1, wherein the recycled polyurethane foam is molded polyurethane foam.

4. The method for producing recycled polyurethane foam according to claim 3, wherein the acid-treated polyol composition comprises a recycled polyol with a number average molecular weight of 4000 or more and a component with a number average molecular weight of 1500 or less.

5. The method for producing recycled polyurethane foam according to claim 3, wherein a polymer polyol is used as a raw material for the decomposed polyurethane foam.

6. The method for producing recycled polyurethane foam according to any one of claims 1 to 5, wherein the acid-treated polyol composition has a peak in the region of a number average molecular weight of 1500 or less in the molecular weight distribution on a standard polyol basis measured by gel permeation chromatography (GPC).

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