Method for producing purified polyols

Abstract

To provide a method for producing a purified polyol which is less likely to cause the reaction product to adhere to a reaction tank or stirring blades when removing an amine compound contained in a crude polyol and can remove an amine compound contained in a crude polyol at a relatively low temperature.SOLUTION: There is provided a method for producing a purified polyol which comprises: a first step of mixing a crude polyol containing an amine compound with an organosulfonic acid to form a mixed solution and reacting the amine compound with the organosulfonic acid in the mixed solution; and a second step of removing the reaction product of the amine compound and the organosulfonic acid from the mixed solution. The crude polyol preferably is a decomposed and recovered polyol. The organosulfonic acid preferably is an aromatic sulfonic acid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing purified polyols, and more particularly to a method for producing purified polyols by removing amine compounds from crude polyols containing amine compounds. [Background technology]

[0002] Polyurethane refers to a polymer compound having a urethane bond (-NH-C(O)O-). Generally, polyurethane is obtained by polymerizing the hydroxyl group (-OH) of a polyol with the isocyanate group (-NCO) of a polyfunctional isocyanate. Polyurethane is known to exhibit diverse properties by optimizing the type of polyol and / or isocyanate used. Therefore, polyurethane is used in various applications such as automotive parts, synthetic leather, paints, and adhesives. Furthermore, polyurethane foam, obtained by foaming polyurethane, is used in applications such as thermal insulation and cushioning materials.

[0003] In recent years, the recycling of various plastic products has been considered from the perspective of protecting the global environment. Methods of plastic recycling include: (a) Material recycling, which reuses plastic as is. (b) Chemical recycling, which involves breaking down plastics and reusing them as chemical raw materials. (c) Thermal recycling, which reuses plastic as fuel. These are some of the known facts.

[0004] Various methods have been proposed for recycling polyurethane, and some of them are already being implemented industrially. Of these methods, chemical recycling of polyurethane involves adding a decomposition agent to pulverized polyurethane to decompose it into polyols and amine compounds derived from polyfunctional isocyanates. Known decomposition methods include amine decomposition, glycol decomposition, and hydrolysis. In any case, the resulting decomposition product separates into two phases: a lower phase mainly composed of amine compounds and an upper phase mainly composed of polyols. Therefore, polyols can be easily recovered from the upper phase.

[0005] However, the polyol recovered from the upper phase contains trace amounts of amine compounds. These amine compounds also function as catalysts in the urethane reaction. Therefore, for example, if polyols containing amine compounds (hereinafter also referred to as "crude polyols") are reused as raw materials for the manufacture of polyurethane foam, the urethane reaction proceeds rapidly, making it difficult to control the bubbles.

[0006] Therefore, various proposals have been made to solve this problem. For example, Patent Document 1 contains: (a) Add oxalic acid or maleic anhydride to a polyol containing a polyamine to precipitate the polyamine as an oxalate or maleate, (b) Remove precipitates A method for purifying polyols is disclosed. The document states that polyamines can be almost completely removed from crude polyols using this method.

[0007] Patent document 2 does not describe a method for purifying polyols, (a) The alkaline catalyst contained in the crude polyether polyol is neutralized with vinyl carboxylic acids or vinyl sulfonic acids. (b) Add another vinyl monomer to this and carry out vinyl polymerization. A method for producing polymer polyols is disclosed. The document states: (A) By this method, polymer polyols can be produced using unpurified polyols (polyols containing an alkaline catalyst), (B) By this method, the alkali metal vinyl carboxylic acid salt or alkali metal vinyl sulfonic acid salt generated by the neutralization of the alkaline catalyst can be immobilized in the polymer, and (C) The alkali metal salts immobilized in the polymer also function as catalysts in the production of polyurethane foam. Therefore, using such polymer polyols in the production of polyurethane foam can reduce the amount of catalyst used. It is stated.

[0008] Patent Document 3 does not describe a method for purifying polyols, (a) Add polynitrile oxide or hydroxide mononitrile oxide to a polyol composition containing a monool having terminal unsaturated groups, (b) React a monool having terminal unsaturated groups with polynitrile oxide or hydroxylated mononitrile oxide. A method for producing a polyol composition is disclosed. The document states that a polyol composition with a low degree of unsaturation can be obtained by this method.

[0009] Furthermore, Patent Document 4 does not describe a method for purifying polyols, (a) React 2-butyl-2-ethyl-1,3-propanediol (BEPD) with octanoic acid (monocarboxylic acid) and adipic acid (dicarboxylic acid) in the presence of a catalyst. (b) After the reaction mixture has cooled, the acidic component is neutralized with triethylamine (base). A method for producing composite esters is disclosed. The document states that this method allows for the recovery of complex esters in high yield.

[0010] When using the method described in Patent Document 1, an amine compound can be removed from crude polyol. However, when the amine compound contained in the crude polyol is reacted with a dicarboxylic acid or its anhydride, if the reaction temperature is low, the removal of the amine compound becomes insufficient. On the other hand, if the reaction temperature is increased, the removal efficiency of the amine compound improves. However, as the reaction temperature increases, the reaction product tends to adhere to the reaction tank and stirring blades. Also, as the reaction temperature increases, the deterioration of the polyol progresses, requiring high energy, or there is a problem of inferior safety during operation.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0012] The problem to be solved by the present invention is to provide a method for producing a purified polyol in which the reaction product is unlikely to adhere to the reaction tank and stirring blades when removing the amine compound contained in the crude polyol. Another problem to be solved by the present invention is to provide a method for producing a purified polyol capable of removing the amine compound contained in the crude polyol at a relatively low temperature.

Means for Solving the Problems

[0013] In order to solve the above problems, the method for producing a purified polyol according to the present invention is as follows: A first step involves mixing a crude polyol containing an amine compound with an organic sulfonic acid to form a mixture, and reacting the amine compound with the organic sulfonic acid in the mixture. A second step involves removing the reaction product of the amine compound and the organic sulfonic acid from the aforementioned mixture. It is equipped with. [Effects of the Invention]

[0014] When an organic sulfonic acid is added to a crude polyol, the amine compound and the organic sulfonic acid react to obtain a reaction product. The reaction product obtained in this way tends to precipitate in the mixture as relatively coarse particles or aggregates thereof (coarse particles with a diameter of about 1 mm to several tens of mm), and does not adhere to the reaction vessel or stirring blades. Furthermore, organic sulfonic acids react with amine compounds at lower temperatures than dicarboxylic acids or their anhydrides. Therefore, using organic sulfonic acids allows for a relatively lower reaction temperature. This also suppresses the degradation of polyols, reduces energy costs, and improves safety during the process. [Modes for carrying out the invention]

[0015] One embodiment of the present invention will be described in detail below. [1. Method for producing purified polyols] The method for producing purified polyols according to the present invention is: A first step involves mixing a crude polyol containing an amine compound with an organic sulfonic acid to form a mixture, and reacting the amine compound with the organic sulfonic acid in the mixture. A second step involves removing the reaction product of the amine compound and the organic sulfonic acid from the aforementioned mixture. It is equipped with.

[0016] [1.1. 1st step] First, a crude polyol containing an amine compound is mixed with an organic sulfonic acid to form a mixture, and the amine compound and the organic sulfonic acid are reacted in the mixture (step 1).

[0017] [1.1.1. Crude Polyols] "Crude polyol" refers to a polyol that contains amine compounds as impurities. In the present invention, the type of crude polyol, the type of polyol contained in the crude polyol, and the type of amine compound contained in the crude polyol are not particularly limited, and the present invention can be applied to any crude polyol.

[0018] The amount of amine compounds contained in the crude polyol is not particularly limited, but the present invention is suitable as a method for purifying crude polyols containing trace amounts of amine compounds. Specifically, the crude polyol is preferably one in which the total amine value is 250 mgKOH / g or less. More preferably, the total amine value is 200 mgKOH / g or less, or 150 mgKOH / g or less.

[0019] Crude polyols are preferably decomposed and recovered polyols obtained by decomposing polyurethane. In this case, the method of decomposing polyurethane is not particularly limited. Examples of decomposition methods include amine decomposition, glycol decomposition, and hydrolysis. Regardless of the decomposition method used, the resulting decomposition product separates into two phases: a lower phase mainly composed of amine compounds and an upper phase mainly composed of polyols. Therefore, crude polyols can be easily recovered from the upper phase.

[0020] [1.1.2. Organic sulfonic acids] Organic sulfonic acid functions as a scavenger to remove amine compounds contained in crude polyols. When organic sulfonic acid is added to crude polyol and heated to a predetermined temperature, the organic sulfonic acid reacts with the amine compounds. Organic sulfonic acid has high reactivity with amine compounds and the reaction product has high cohesiveness, so coarse reaction products tend to precipitate. By optimizing the reaction conditions, the reaction product precipitates as coarse particles with a diameter of approximately 1 mm to several tens of mm. Furthermore, unlike oxalic acid, organic sulfonic acids have the advantage of reacting with amine compounds at low temperatures, and the reaction products do not adhere to the reaction vessel or stirring blades.

[0021] In the present invention, the type of organic sulfonic acid is not particularly limited, and the most suitable material can be selected depending on the purpose. The organic sulfonic acid may be an aliphatic sulfonic acid or an aromatic sulfonic acid. Aromatic sulfonic acid is particularly preferred. Since aromatic sulfonic acid is less expensive than aliphatic sulfonic acid, crude polyols can be purified at a low cost.

[0022] Examples of organic sulfonic acids include the following. The mixture may contain one or more organic sulfonic acids.

[0023] Examples of aliphatic sulfonic acids include, Methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, n-octyl sulfonic acid, pentadecyl sulfonic acid, trifluoromethanesulfonic acid, Trichloromethanesulfonic acid, 1,2-ethanedisulfonic acid, 1,3-propanedisulfonic acid, aminomethanesulfonic acid, 2-aminoethanesulfonic acid, cyclopentanesulfonic acid, cyclohexanesulfonic acid, Camphor sulfonic acid, 3-cyclohexylaminopropanesulfonic acid, sulfamic acid These are some examples.

[0024] Examples of aromatic sulfonic acids include, Benzenesulfonic acid, n-butylbenzenesulfonic acid, n-octylbenzenesulfonic acid, n-dodecylbenzenesulfonic acid, Pentadecylbenzenesulfonic acid, 2,5-dimethylbenzenesulfonic acid, 2,5-Dibutylbenzenesulfonic acid, o-Aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 5-amino-2-methylbenzenesulfonic acid, 3,5-diamino-2,4,6-trimethylbenzenesulfonic acid, 2,4-Dinitrobenzenesulfonic acid, p-Chlorobenzenesulfonic acid, 2,5-Dichlorobenzenesulfonic acid, o-Phenolsulfonic acid, p-phenolsulfonic acid, m-phenolsulfonic acid, cumenesulfonic acid, xylene sulfonic acid, o-cresol sulfonic acid, m-cresol sulfonic acid, p-cresol sulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, m-toluenesulfonic acid, 2-naphthalenesulfonic acid, 1-naphthalenesulfonic acid, Isopropylnaphthalene sulfonic acid, dodecylnaphthalene sulfonic acid, Dinonylnaphthalene sulfonic acid, dinonylnaphthalenedisulfonic acid, 1,5-Naphthalenedisulfonic acid, 2,7-Naphthalenedisulfonic acid, 4,4-biphenyldisulfonic acid, anthraquinone-2-sulfonic acid, m-benzenedisulfonic acid, 2,5-diamino-1,3-benzenedisulfonic acid, Aniline-2,4-disulfonic acid, anthraquinone-1,5-disulfonic acid, Polystyrene sulfonic acid These are some examples.

[0025] Aromatic sulfonic acids are particularly preferably toluenesulfonic acid, phenolsulfonic acid, or cresolsulfonic acid. (a) When these aromatic sulfonic acids are used, reaction products with high specific gravity and easy separation are obtained, and, (b) These aromatic sulfonic acids are generally in circulation and inexpensive, so .

[0026] [1.1.3. M , ,

[0029] , , A , A ,

[0028] , , S , S / M A ratio] The first step preferably includes a step of mixing a crude polyol and an organic sulfonic acid so that the ratio of the number of moles of sulfonic acid groups (M A ) contained in the organic sulfonic acid to the number of moles of amino groups (M S ) contained in the amine compound (= M S / M A ) is within a predetermined range.

[0027] If the amount of the organic sulfonic acid is too small compared to the amine compound contained in the mixed solution, unreacted amine compounds may remain relatively large in amount. Also, due to the small amount of the organic sulfonic acid, the reaction is difficult to proceed chain - like, and the reaction product is difficult to have a high molecular weight. Therefore, the reaction product may precipitate as fine particles with a diameter of less than 1 mm, making the separation of the reaction product difficult. Therefore, the M S / M A ratio is preferably 0.35 or more. The M S / M A ratio is more preferably 0.40 or more, or 0.45 or more.

[0028] Conversely, if the amount of the organic sulfonic acid is excessive compared to the amine compound contained in the mixed solution, unreacted organic sulfonic acids may remain relatively large in amount. Also, due to the excessive amount of the organic sulfonic acid, a large amount of nuclei of the reaction product are generated, and the reaction product is difficult to have a high molecular weight. Therefore, the reaction product may precipitate as fine particles with a diameter of less than 1 mm, making the separation of the reaction product difficult. Therefore, the M S / M A A ratio is preferably 1.10 or less. The M S / M A ratio is more preferably 1.05 or less, or 1.00 or less.

[0029] [1.1.4. Reaction temperature] The first step preferably includes a step of reacting an amine compound with an organic sulfonic acid at a predetermined temperature.

[0030] Generally, the higher the reaction temperature, the faster the reaction between the amine compound and the organic sulfonic acid proceeds. Therefore, a reaction temperature of 50°C or higher is preferred. More preferably, the reaction temperature is 55°C or higher, or 60°C or higher. On the other hand, if the reaction temperature becomes too high, the polyol contained in the mixture may deteriorate. Therefore, the reaction temperature is preferably 100°C or lower. More preferably, the reaction temperature is 95°C or lower, or 90°C or lower.

[0031] [1.2. 2nd process] Next, the reaction product of the amine compound and the organic sulfonic acid is removed from the mixture (second step). This yields a purified polyol.

[0032] In the present invention, the method for removing reaction products is not particularly limited, and the most suitable method can be selected depending on the purpose. Using the method according to the present invention, the reaction products do not adhere to the reaction vessel or stirring blades, and instead precipitate as coarse particles with a diameter of approximately 1 mm to several tens of mm. Therefore, for example, the reaction products can be easily removed from the mixture by filtering the mixture after the reaction.

[0033] [2. Effect] When an organic sulfonic acid is added to a crude polyol, the amine compound and the organic sulfonic acid react to obtain a reaction product. The reaction product obtained in this way tends to precipitate in the mixture as relatively coarse particles or aggregates thereof (coarse particles with a diameter of about 1 mm to several tens of mm), and does not adhere to the reaction vessel or stirring blades. Furthermore, organic sulfonic acids react with amine compounds at lower temperatures than dicarboxylic acids or their anhydrides. Therefore, using organic sulfonic acids allows for a relatively lower reaction temperature. This also suppresses the degradation of polyols, reduces energy costs, and improves safety during the process.

[0034] Furthermore, if the crude polyol is a decomposed and recovered polyol obtained by amine decomposition of polyurethane, the crude polyol may contain not only amine compounds derived from isocyanates but also amine compounds derived from the decomposition agent used to amine decompose the polyurethane. In contrast, the method according to the present invention allows for the simultaneous removal of amine compounds derived from both isocyanates and the decomposition agent from the crude polyol. As a result, a high-quality purified polyol can be obtained. [Examples]

[0035] (Examples 1-10, Comparative Examples 1-4) [1. Test Method] Crude polyols include, (a) Decomposed and recovered polyols obtained by amine decomposition of polyurethane, or (b) Decomposed and recovered polyols obtained by glycol decomposition of polyurethane I used it.

[0036] Furthermore, the acids (scavengers) used to capture amine compounds include: (a) p-toluenesulfonic acid monohydrate (Examples 1-6, 9-10), (b) p-phenolsulfonic acid (Examples 7-8), (c) Oxalic acid (Comparative Examples 1-2), or, (d) Maleic anhydride (Comparative Examples 3-4) I used it.

[0037] Crude polyol and a predetermined amount of scavenging agent were placed in a separable flask. S / M AThe ratio was set to 0.25–1.10. The separable flask was then heated at 50°C–120°C for 3 hours. After the reaction was complete, the reaction solution was filtered through a 10 cm diameter stainless steel mesh (300 mesh).

[0038] [2. Evaluation] [2.1. Amine Value Decrease Rate] The amine value (X0) of the crude polyol before treatment was measured. The amine value (X1) of the filtrate after treatment was also measured. Furthermore, the amine value reduction rate was calculated using the following formula. Amine value reduction rate (%) = (X1 - X0) × 100 / X0

[0039] [2.2. Separability] 100g of the reaction solution was filtered by gravity alone through a 10cm diameter stainless steel mesh (300 mesh). Clogging was visually inspected during this process.

[0040] [2.3. Adhesion] The presence or absence of reaction products adhering to the equipment was visually evaluated.

[0041] [3. Results] Table 1 shows the results. Table 1 also includes the history of each sample. Furthermore, regarding the amine removal effect, "○" indicates that the amine value reduction rate is 80% or more, "△" indicates that the amine value reduction rate is 50% or more but less than 80%, and "×" indicates that the amine value reduction rate is less than 50%. Regarding separation performance, "○" indicates that no clogging occurred during filtration, "△" indicates that some clogging occurred during filtration, reducing the filtration speed, but filtration was still completed, and "×" indicates that clogging occurred during filtration. Regarding adhesion to the equipment, "○" indicates that there is no adhesion of the reaction product, or only a small amount is present, while "×" indicates that the reaction product has completely solidified. From Table 1, the following can be seen.

[0042] (1) Comparative Example 1 showed a high amine removal effect and good separation. However, the reaction product in Comparative Example 1 adhered to the apparatus. This is thought to be because oxalic acid was used as a scavenging agent and the reaction temperature was 120°C. (2) In Comparative Example 2, the reaction product did not adhere to the apparatus. However, in Comparative Example 2, the amine removal effect was reduced, and the separation performance was also reduced. This is thought to be because the reaction temperature was 70°C.

[0043] (3) Comparative Example 3 showed a high amine removal effect and good separation. However, the reaction product in Comparative Example 3 adhered to the apparatus. This is thought to be because maleic anhydride was used as a scavenging agent and the reaction temperature was 120°C. (4) Comparative Example 4 showed a slightly improved amine removal effect compared to Comparative Example 2. However, Comparative Example 4 showed reduced separation performance. Furthermore, in Comparative Example 4, the reaction product adhered to the apparatus despite the reaction temperature being 70°C. This is thought to be due to the use of maleic anhydride as a scavenging agent.

[0044] (5) In all of Examples 1 to 8, the amine removal effect was high, the separation was good, and almost no adhesion of the reaction product to the equipment was observed. (6) Examples 4 and 8 showed a slight decrease in separation ability. This is because M S / M A This is likely because the ratio is slightly higher than average. (7) In Example 9, the amine removal effect was slightly reduced, but no adhesion of the reaction product to the equipment was observed. However, in Example 9, the separation performance was reduced. This is because M S / M A This is thought to be because the ratio was too small, causing the reaction product to precipitate as fine particles. (8) Example 10 showed a high amine removal effect, and no adhesion of the reaction product to the equipment was observed. However, the separation performance of Example 10 was reduced. This is because M S / M A This is thought to be because the ratio was too large, causing the reaction product to precipitate as fine particles.

[0045] [Table 1]

[0046] Although embodiments of the present invention have been described in detail above, the present invention is not limited in any way to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. [Industrial applicability]

[0047] The method for producing purified polyols according to the present invention can be used as a method for purifying decomposed and recovered polyols.

Claims

1. A first step involves mixing a crude polyol containing an amine compound with an organic sulfonic acid to form a mixture, and reacting the amine compound with the organic sulfonic acid in the mixture. A second step involves precipitating the reaction product of the amine compound and the organic sulfonic acid, and filtering the mixture to remove the reaction product. A method for producing purified polyols, comprising the following:

2. A first step of mixing a crude polyol containing an amine compound with an organic sulfonic acid to form a mixture, and reacting the amine compound with the organic sulfonic acid in the mixture, A second step involves removing the reaction product of the amine compound and the organic sulfonic acid from the aforementioned mixture. Equipped with, The crude polyol is a decomposed and recovered polyol. A method for producing purified polyols.

3. The method for producing a purified polyol according to claim 1 or 2, wherein the organic sulfonic acid is an aromatic sulfonic acid.

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