Catalyst for polyurethane resin production, its applications, and method for producing the same.

Abstract

To provide a catalyst for production of polyurethane resin with reduced malodors.SOLUTION: A catalyst is used that comprises an aqueous solution of an amine compound (A) represented by formula (1), wherein the aqueous solution has a content of 2-ethylpyrazine of 3.9 ppm or less. [R1, R2, R3, R4, and R5 each represent H, a C1-4 alkyl group, a hydroxy group, a hydroxymethyl group, or a C1-4 alkoxy group].SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a catalyst for producing polyurethane resin, its use, and its production method.

Background Art

[0002] Polyurethane resin is produced using polyol and polyisocyanate as main raw materials, and a catalyst, foaming agent, surfactant, flame retardant, crosslinking agent, etc. are added as necessary. The resulting polyurethane resin is processed into soft foams such as automotive seat cushions, mattresses, and furniture, semi-rigid foams such as automotive instrument panels, headrests, and armrests, and hard foams used in electric refrigerators, building materials, etc., and is widely used.

[0003] When producing the above polyurethane resin, a tertiary amine compound is used as a catalyst. However, due to its volatility, there is a concern that the tertiary amine compound may pollute the working environment at the polyurethane resin production site. Furthermore, it gradually volatilizes from the produced polyurethane resin product, polluting the use environment and having a concern of causing adverse effects such as discoloration of vinyl chloride resin and clouding of polycarbonate resin existing in the use environment. As a means to eliminate the above concerns, for example, the invention described in Patent Document 1 below has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding the hydroxyalkyltriethylenediamines disclosed in Patent Document 1 and the catalyst composition containing the same, although they were able to solve the above concerns, the catalyst composition itself had a faint odor, and reduction of the faint odor was required.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventor found that the faint odor was derived from aromatic compounds such as 2-ethylpiperazine, which are trace by-products of the acid-catalyzed cyclization reaction, and that the odor could be reduced more than before by reducing the content of the aromatic compounds, thus completing the present invention.

[0007] One aspect of the present invention relates to a catalyst for producing a polyurethane resin, its use, and its production method as shown below.

[0008] [1] A catalyst for producing a polyurethane resin, which is an aqueous solution of an amine compound (A) represented by the following general formula (1), wherein the content of 2-ethylpyrazine in the aqueous solution is 3.9 ppm or less.

[0009]

Chemical Formula

[0010] [In the above general formula (1), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a hydroxymethyl group, or an alkoxy group having 1 to 4 carbon atoms. a and b are each independently 0 or 1, and satisfy the relationship a + b = 1.] [2] In the general formula (1), R 1 、R 2 、R 3 、R4 and R 5 The catalyst for producing a polyurethane resin according to [1], wherein each of them is independently a hydrogen atom or a methyl group.

[0011] [3] The catalyst for producing a polyurethane resin according to [1] or [2], wherein the concentration of the amine compound (A) in the aqueous solution is 10 to 70% by mass.

[0012] [4] A method for producing a polyurethane resin, comprising reacting a polyol with a polyisocyanate in the presence of the catalyst for producing a polyurethane resin according to any one of [1] to [3].

[0013] [5] A method for producing the catalyst for producing a polyurethane resin according to any one of [1] to [3], comprising the following steps. Step 1: In the presence of an acid catalyst, the piperazine compound represented by the following general formula (2)

[0014]

Chemical formula

[0015] [In the above general formula (2), R 1 , R 2 , R 3 , R 4 and R 5 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a hydroxymethyl group, or an alkoxy group having 1 to 4 carbon atoms.] is intramolecularly cyclized to produce an amine compound represented by the above general formula (1), and the obtained amine compound is purified by fractional distillation. Step 2: A step of dissolving the amine compound purified in Step 1 in water to produce an aqueous solution. Step 3: A step of contacting the aqueous solution obtained in Step 2 with activated carbon and then isolating the aqueous solution.

Advantages of the Invention

[0016] The catalyst for polyurethane resin production of the present invention has the effect of having less odor and less unpleasant handling compared to conventional catalysts. Furthermore, the catalyst for polyurethane resin production of the present invention provides a manufacturing method that produces polyurethane resin with even lower odor compared to conventional catalysts. [Modes for carrying out the invention]

[0017] An embodiment of the present invention will be described in detail below. Unless otherwise specified in this specification, "A to B" representing a numerical range means "greater than or equal to A and less than or equal to B".

[0018] One embodiment of this invention is a catalyst for the production of polyurethane resin, comprising an aqueous solution of an amine compound (A) represented by the general formula (1) above, wherein the 2-ethylpyrazine content in the aqueous solution is 3.9 ppm or less.

[0019] In the above general formula (1), R 1 , R 2 , R 3 , R 4 and R 5 Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a hydroxyl group, a hydroxymethyl group, or a C1-C4 alkoxy group, and is not particularly limited, but examples include each independently a hydrogen atom, a hydroxyl group, a hydroxymethyl group, a C1-C4 alkyl group (e.g., methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group), or a C1-C4 alkoxy group (e.g., methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, or tert-butoxy group). Of these, each is preferably independently a hydrogen atom, a methyl group, an ethyl group, a hydroxymethyl group, or a methoxy group.

[0020] In the present invention, preferred amine compound (A) is, for example, R in the above general formula (1). 1 , R2 , R 3 , R 4 and R 5 However, each independently represents a compound that represents a hydrogen atom, a methyl group, an ethyl group, or a hydroxymethyl group (however, R 1 , R 2 , R 3 , R 4 and R 5 Not all of them represent the same substituent), in the above general formula (1), R 1 , R 2 , R 3 , R 4 and R 5 A compound in which all of are methyl groups, or in the above general formula (1), R 1 , R 2 , R 3 , R 4 and R 5 Examples include compounds in which all are hydrogen atoms, and a more preferred amine compound (A) is one in which R in general formula (1) 1 , R 2 , R 3 , R 4 and R 5 However, examples include compounds in which each is independently a hydrogen atom or a methyl group, and a more preferred amine compound (A) is, in the above general formula (1), R 1 , R 2 , R 3 , R 4 and R 5 Examples include compounds in which all atoms are hydrogen atoms.

[0021] In the general equation (1) above, a and b are independently either 0 or 1, and the relationship a + b = 1 is satisfied.

[0022] Specific examples of the amine compound (A) represented by the general formula (1) above include, for example, the following compounds (example compound 1 to example compound 28), but the present invention is not limited to these.

[0023] In the present invention, preferred amine compounds (A) include the following exemplary compound 1 and / or exemplary compound 15.

[0024] [ka]

[0025] The method for producing the amine compound (A) represented by the above general formula (1) is not particularly limited, but for example, it can be produced by the cyclization reaction of dihydroxyalkylpiperazines (see, for example, Japanese Patent Application Publication No. 2010-37325).

[0026] Furthermore, the method for producing the amine compound (A) represented by the above general formula (1) is not particularly limited, but it can be produced by methods such as those described in Khimiya Geterotsiklicheskikh Soedinenil, 10, 1404 (1980) and International Publication No. 95 / 18104. It can also be produced by intramolecular cyclization of ethylene oxide adducts of hydroxyalkylpiperazines derived by methods such as those described in Journal of Medicinal Chemistry (1993), 36(15), 2075-2083 and Japanese Patent Publication No. 2010-120887. Moreover, it can be produced by methods such as those described in Japanese Patent Publication No. 2010-37325, i.e., by the cyclization reaction of dihydroxyalkylpiperazines.

[0027] A method for producing the amine compound represented by formula (1) having a substituent can be used by using the corresponding substituted piperazine. A method for producing substituted piperazines can be used by the known techniques for the synthesis of hydroxyalkylpiperazines described above.

[0028] One embodiment of the present invention is a catalyst for producing polyurethane resin, comprising an aqueous solution of the amine compound (A) represented by the general formula (1) above. The content of the amine compound (A) in the aqueous solution is not particularly limited, but is preferably in the range of 10 to 70% by weight, more preferably in the range of 35 to 65% by weight, and even more preferably in the range of 40 to 60% by weight.

[0029] The content of amine compound (A) relative to the total catalyst for polyurethane resin production is not particularly limited, but is preferably in the range of 10 to 70% by weight, more preferably in the range of 35 to 65% by weight, and even more preferably in the range of 40 to 60% by weight.

[0030] The water in the aqueous solution of the amine compound (A) represented by the general formula (1) of the present invention is not particularly limited, but for example, distilled water, deionized water, purified water, or pure water can be used.

[0031] The aqueous solution of the amine compound (A) represented by the above general formula (1) of the present invention is characterized by containing 2-ethylpyrazine, and its content is 3.9 ppm or less. Regarding the 2-ethylpyrazine content, a range of 0.01 to 3.9 ppm is preferred, a range of 0.02 to 3.5 ppm is more preferred, and a range of 0.03 to 3.0 ppm is even more preferred, in terms of achieving excellent effects of the present invention.

[0032] The content of 2-ethylpyrazine described above can be quantified using generally known analytical methods. In the present invention, the content was quantified by the method shown in the examples described later.

[0033] The 2-ethylpyrazine mentioned above is one of the by-products of the acid-catalyzed cyclization reaction described later. In this acid-catalyzed cyclization reaction, it is thought that numerous aromatic compounds, not just 2-ethylpyrazine, are produced as by-products, but 2-ethylpyrazine is the main component. The amount of these numerous aromatic compounds is very small, making qualitative and quantitative analysis extremely difficult. Step 3, described later, aims to remove 2-ethylpyrazine by activated carbon treatment, but the aforementioned by-product aromatic compounds, which have similar physical properties to 2-ethylpyrazine, are also removed by activated carbon in the same way as 2-ethylpyrazine.

[0034] Another embodiment of this model is a method for producing polyurethane resin, characterized by reacting a polyol with a polyisocyanate in the presence of the above-mentioned catalyst for producing polyurethane resin.

[0035] The polyol used in the above-mentioned manufacturing method can be any conventionally known polyol, and is not particularly limited; however, polyols with an average hydroxyl value in the range of 20 to 1000 mgKOH / g are generally preferred. When manufacturing flexible polyurethane resins or semi-rigid polyurethane resins, polyols with an average hydroxyl value in the range of 20 to 100 mgKOH / g are preferred, and when manufacturing rigid polyurethane resins, polyols with an average hydroxyl value in the range of 100 to 800 mgKOH / g are preferred.

[0036] The polyisocyanates used in the above-mentioned manufacturing method may be conventionally known and are not particularly limited, but examples include toluene diisocyanate (hereinafter sometimes referred to as "TDI") or its derivatives, diphenylmethane diisocyanate (hereinafter sometimes referred to as "MDI") or its derivatives, aromatic polyisocyanates such as naphthylene diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as dicyclohexyl diisocyanate and isophorone diisocyanate, or mixtures thereof. Of these, TDI or its derivatives, or MDI or its derivatives are preferred, and these may be used alone or in combination.

[0037] Examples of TDI and its derivatives include mixtures of 2,4-TDI and 2,6-TDI, and terminal isocyanate prepolymer derivatives of TDI. Examples of MDI and its derivatives include polyphenylmethylene diisocyanate mixtures of MDI and its polymers, and diphenylmethane diisocyanate derivatives having terminal isocyanate groups.

[0038] Of these isocyanates, TDI and its derivatives, MDI and its derivatives, or both are preferably used for flexible polyurethane resins and semi-rigid polyurethane resin products. Furthermore, a mixture of polyphenyl polymethylene diisocyanate, a polymer of MDI, is preferably used for rigid polyurethane resins.

[0039] While there are no particular limitations on the mixing ratio of these polyisocyanates and polyols, the isocyanate index ([isocyanate group] / [active hydrogen group that can react with isocyanate group] × 100) is generally preferred to be in the range of 50 to 400. More preferably, it is in the range of 50 to 200, and even more preferably, in the range of 60 to 120.

[0040] The polyurethane resin production catalyst of the present invention may be used alone as a catalyst for polyurethane resin production, but may also be used in combination with foaming catalysts, organometallic catalysts, carboxylate metal salt catalysts, or quaternary ammonium salt catalysts as needed.

[0041] The organometallic catalyst can be any conventionally known catalyst and is not particularly limited, but examples include stanus diacetate, stanus dioctoate, stanus dioleate, stanus dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dioctyltin dilaurate, lead octanoate, lead naphthenate, nickel naphthenate, or cobalt naphthenate.

[0042] The carboxylic acid metal salt catalyst can be any conventionally known catalyst and is not particularly limited, but examples include alkali metal salts and alkaline earth metal salts of carboxylic acids. Here, the carboxylic acid is not particularly limited, but examples include aliphatic mono or dicarboxylic acids such as acetic acid, propionic acid, 2-ethylhexanoic acid, and adipic acid, aromatic mono or dicarboxylic acids such as benzoic acid or phthalic acid. Furthermore, suitable metals for forming the carboxylic acid salt include alkali metals such as lithium, sodium, and potassium, calcium, or alkaline earth metals such as magnesium.

[0043] The quaternary ammonium salt catalyst can be any conventionally known catalyst and is not particularly limited, but examples include tetraalkylammonium halides such as tetramethylammonium chloride, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetramethylammonium 2-ethylhexanoate, 2-hydroxypropyltrimethylammonium forate, 2-hydroxypropyltrimethylammonium, or tetraalkylammonium organic acid salts such as 2-ethylhexanoate.

[0044] In the above manufacturing method, the above-mentioned catalyst for polyurethane resin production can be used alone or in combination with the other catalysts mentioned above. When mixing and preparing these, a solvent such as dipropylene glycol, ethylene glycol, 1,4-butanediol, or water may be used if necessary.

[0045] In the above manufacturing method, the amount of the polyurethane resin production catalyst used is preferably in the range of 0.1 to 30 parts by weight, and more preferably in the range of 0.5 to 20 parts by weight, per 100 parts by weight of the polyol used.

[0046] Another embodiment of this model is a method for producing the above-mentioned catalyst for polyurethane resin, comprising the following steps. Step 1: In the presence of an oxidation catalyst, the following general formula (2)

[0047] [ka]

[0048] [In the above general formula (2), R 1 , R 2 , R 3 , R 4 and R 5 Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a hydroxyl group, a hydroxymethyl group, or a C1-C4 alkoxy group. The process involves intramolecular cyclization of a piperazine compound represented by the above general formula (1) to produce an amine compound represented by the above general formula (1), and then purifying the obtained amine compound by fractional distillation. Step 2: A step to produce an aqueous solution by dissolving the amine compound purified in Step 1 in water. Step 3: The aqueous solution obtained in Step 2 is brought into contact with activated carbon, and then the aqueous solution is isolated. In the general formula (2) above, R 1 , R 2 , R 3 , R 4 and R 5 The definition and preferred range of R in the general formula (1) above is as follows: 1 , R 2 , R 3 , R 4 and R 5 This is synonymous with the definition and preferred range of [the term].

[0049] In step 1, the method for intramolecular cyclization is not particularly limited, but a known method can be used. For example, the method described in Japanese Patent Application Publication No. 2010-37325 can be used.

[0050] The acid catalyst in step 1 is not particularly limited, but examples include phosphorus-containing substances such as metal phosphates and organophosphorus compounds, nitrogen-containing substances, sulfur-containing substances, niobium-containing substances, silica, alumina, silica-alumina, silica-titania, zeolites, heteropoly acids, group IVB metal oxide condensation catalysts, group VIB metal-containing condensation catalysts, Brønsted acids, Lewis acids, phosphorus amides, etc. Among these, metal phosphates are preferred, and specific examples of such metal phosphates include aluminum phosphate, magnesium phosphate, calcium phosphate, barium phosphate, strontium phosphate, etc.

[0051] The water used in step 2 can be the same as the water described above.

[0052] The method for dissolving the amine compound produced in step 1 in water can be carried out based on generally known techniques, such as by stirring and dissolution or heating and dissolution.

[0053] Examples of activated carbon used in step 3 of the preceding stage include mineral-based activated carbon and plant-based activated carbon. Specific examples of mineral-based activated carbon include coal-based activated carbon and petroleum-based activated carbon. Specific examples of plant-based activated carbon include wood-based activated carbon and coconut shell activated carbon, with wood-based activated carbon being preferred.

[0054] Any shape of activated carbon suitable for step 3 above can be used, but examples include granular activated carbon such as crushed charcoal, granular charcoal, spherical charcoal or pelletized charcoal, fibrous activated carbon such as fibers or cloth, specially molded activated carbon such as sheets, molded bodies or honeycomb shapes, or powdered activated carbon.

[0055] The average pore diameter of the activated carbon is not particularly limited, but is usually 0.1 to 20 nm, preferably 0.5 to 5.0 nm, more preferably 2.0 to 5.0 nm, and even more preferably 3.0 to 5.0 nm. The average pore diameter of the activated carbon can be calculated from the nitrogen adsorption isothermal adsorption curve using the BJH method.

[0056] Specifically, examples of activated carbon include Carboraffin, Strong Shirasagi (registered trademark), Purified Shirasagi, Special Shirasagi, Shirasagi A, Shirasagi C, Shirasagi C-1, Shirasagi DO-2, Shirasagi DO-5, Shirasagi DO-11, Shirasagi DC, Shirasagi DO, Shirasagi Gx, Shirasagi G, Shirasagi GH, Shirasagi FAC-10, Shirasagi FPG-1, Shirasagi M, Shirasagi P, Shirasagi PHC, Shirasagi Gc, Shirasagi GH, Shirasagi GM, Shirasagi GS, Shirasagi GT, Shirasagi GAA, Shirasagi GOC, Shirasagi GOX, and White Examples include, but are not limited to, Sagi APRC, Shirasagi TAC, Shirasagi MAC, Shirasagi XRC, Shirasagi NCC, Shirasagi SRCX, Shirasagi Wc, Shirasagi LGK, Shirasagi KL, Shirasagi WH, Shirasagi W, Shirasagi WHA, Shirasagi LH, Shirasagi KL, Shirasagi LGK, Shirasagi MAC-W, Shirasagi S, Shirasagi Sx, Shirasagi X2M, Shirasagi X7000, Shirasagi X7100, Shirasagi DX7-3, Molcybon, ACF, GLC, Taiko A, Taiko S, Taiko K, Taiko KA, Taiko Q, Taiko Y, Norit (registered trademark) SP, Norit CNI, Norit GBG, or Norit TEST EUR.

[0057] Examples of wood-based activated carbon include Tokusei Shirasagi, Kyoryoku Shirasagi, Shirasagi P, Shirasagi C, Shirasagi A, Taiko Y, Taiko KA, Taiko M, Taiko A, Norit GSP, or Norit CNI.

[0058] In step 3 described above, the means for contacting the aqueous solution obtained in step 2 with activated carbon are not particularly limited, but examples include batch methods, membrane treatment methods, or column chromatography methods, and an appropriate form of activated carbon is selected according to each method. If necessary, it can also be used in the form of particles in which activated carbon is encapsulated in a porous polymer or gel, or in the form of a membrane or cartridge in which activated carbon is adsorbed, fixed, or molded using a support material or fiber such as polypropylene or cellulose.

[0059] Examples of activated carbon membranes or cartridges include, but are not limited to, CUNO activated carbon filter cartridges, Zeta Plus® activated carbon filter cartridges, Millistack® Plus activated carbon filters, Supra AKS1 filters, AKS1 filters, Stax® AKS1, Adole, K Filter®, activated carbon sheets, Hemax, Hemosorba®, Hemocolumn, or Hesels. Among these, examples of wood-based activated carbon membranes or cartridges include Zeta Plus activated carbon filter cartridges, Supra AKS1 filters, AKS1 filters, or Stax AKS1.

[0060] In step 3, when the activated carbon is brought into contact with the aqueous solution obtained in step 2, the activated carbon and the aqueous solution can be separated by methods such as filter filtration, and the aqueous solution can be isolated.

[0061] In step 3, if the cartridge-shaped activated carbon is brought into contact with the aqueous solution obtained in step 2, the aqueous solution can be isolated by passing the aqueous solution through the cartridge. [Examples]

[0062] The present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0063] The measurement and evaluation methods used in the examples and comparative examples are as follows. [Method for quantifying 2-ethylpyrazine] The amount of 2-ethylpyrazine was quantified using a headspace GC analyzer (Alpha-Moss Japan, Flash GC Nose HERACLES II). (Sampling conditions) Incubation: 60°C, 20 minutes Headspace injection: 5000 μL at 250 μL / second (Equipment conditions) Column: MXT-5 (slightly polar, 10m, 180μm ID, 0.4μm) Carrier gas flow rate: Hydrogen 1.6 mL / min Flame ionization detector (FID) temperature: 260°C Injector temperature: 220℃ Oven temperature: 40°C (10 seconds) ~ 1.5°C / second ~ 250°C (60 seconds) Injection time 25 seconds Trap temperature 40℃ Trap time: 30 seconds <Creating a calibration curve> A standard stock solution (ethanol solvent) was prepared to contain 2-ethylpyrazine at a concentration of 1000 ppm. This was then diluted with pure water to prepare 2-ethylpyrazine preparations at concentrations of 0.05 ppm, 0.1 ppm, 0.2 ppm, 0.4 ppm, and 0.8 ppm. 10 mL of each preparation was placed in a 20 mL vial containing 4 g of sodium chloride to prepare calibration curve samples. Each calibration curve sample was analyzed using a headspace GC instrument, and a calibration curve was created from the sample concentration and peak area. <Preparation of analytical samples> 0.715 g of the catalyst composition prepared in the examples was diluted to 10 mL with pure water and placed in a 20 mL vial containing 4 g of sodium chloride to prepare the analytical sample. [Determination of Odor of Catalyst Composition] 15 g of the catalyst composition prepared in the examples was placed in a 20 mL vial, and an in-house panelist determined whether an amine odor could be detected.

[0064] ○: No amine odor, ×: Amine odor present. [Odor assessment of polyurethane resin] Internal panelists smelled the foam immediately after foam molding and determined whether an amine odor could be detected.

[0065] ○: No amine odor, ×: Amine odor present.

[0066] Manufacturing Example 1 (Preparation of Catalyst 1 for Gas-Phase Reaction). 40g of commercially available aluminum phosphate (Kishida Chemical Co., Ltd.) was mixed with 300ml of water to make a slurry solution. Then, 6.4g of cesium nitrate (Wako Pure Chemical Industries, Ltd.) (metal ratio 10 mol%) dissolved in 100ml of water was mixed in, and the mixture was dehydrated using an evaporator to obtain 48.6g of a white solid. 0.42g of graphite (1 wt%) was added to this solid, and then a tablet press was used to obtain molded products with a diameter of 5mm and a thickness of 2mm. These molded products were calcined in a muffle furnace at 450°C for 6 hours to obtain catalyst 1 for gas-phase reaction.

[0067] Manufacturing Example 2 (Synthesis of the amine compound shown in Exemplary Compound 1 and the amine compound shown in Exemplary Compound 15).

[0068] [ka]

[0069] In a 50 L reaction vessel, 15.5 kg (180 mol) of piperazine and 15.6 L of methanol as solvent were charged. Under a nitrogen atmosphere, the temperature was adjusted to 45°C, and then 6.06 kg (54.8 mol) of 3-chloro-1,2-propanediol was added dropwise over 3 hours. The temperature gradually rose during the addition, reaching 75°C at the end. Subsequently, the reaction temperature was adjusted to 70°C, and the mixture was aged for another 3 hours. The reaction conversion rate of piperazine was 100%. After stopping the temperature control, the mixture was left overnight to reach room temperature. 4.6 kg (55 mol) of 48% sodium hydroxide aqueous solution was slowly added dropwise to precipitate the by-product salt. The reaction mixture, which was removed from the bottom of the vessel, was filtered to remove the by-product salt, and then methanol was removed using an evaporator. Next, unreacted piperazine was removed by simple distillation, and then 3-(1'-piperazinyl)-1,2-propanediol (2-A) was isolated by vacuum distillation (white solid, yield 7.9 kg, yield 90%).

[0070] 160 ml of the gas-phase reaction catalyst 1 prepared in Production Example 1 was placed in the center of a quartz glass tube with an inner diameter of 40 mm, and 5 mm outer diameter Raschig rings were packed above and below it. The catalyst layer and Raschig ring layer were kept at 360°C in an electric furnace, and an aqueous solution (2 mol%) of 1.6 kg (10 mol) of the aforementioned 3-(1'-piperazinyl)-1,2-propanediol (2-A) was added from the top at GHSV = 1,500 Hr -1 It was added dropwise at the following rate. Nitrogen gas was also added as a diluent at GHSV = 750 Hr -1 The reaction was carried out in conjunction with the sample. Three hours after the start of the reaction, the reaction solution was collected over one hour and analyzed by gas chromatography. The conversion rate of 3-(1'-piperazinyl)-1,2-propanediol (2-A) was 100%. The reaction solution obtained during the aforementioned one hour contained 1,4-diazabicyclo[2.2.2]octane-2-methanol (42%), represented by example compound 1 above, 3-hydroxy-1,5-diazabicyclo[3.2.2]nonane (6%), represented by example compound 15 above, as well as piperazine (13%) and 1,4-diazabicyclo[2.2.2]octane (1%) with the side chain removed.

[0071] Manufacturing Example 3 (Synthesis of a composition of the amine compound shown in Exemplary Compound 1 and the amine compound shown in Exemplary Compound 15). From the reaction solution obtained in Production Example 2, all components except 1,4-diazabicyclo[2.2.2]octane-2-methanol, which is the amine compound represented by Exemplary Compound 1, and 3-hydroxy-1,5-diazabicyclo[3.2.2]nonane, which is the amine compound represented by Exemplary Compound 15, were fractionated by distillation to obtain approximately 20 g of a composition (pale yellow solid) containing the amine compound represented by Exemplary Compound 1 and the amine compound represented by Exemplary Compound 15. The ratio of [amine compound represented by Exemplary Compound 1] / [amine compound represented by Exemplary Compound 15] was 10 / 1 (by weight).

[0072] Example 1. [Preparation of catalyst composition] 20 g of the composition obtained in Production Example 3 was dissolved in 20 g of pure water to prepare an aqueous solution. 0.8 g of wood-based powdered activated carbon (Carborafin® SS, manufactured by Osaka Gas Chemical Co., Ltd., equivalent to 2% by weight of the aqueous solution) with an average pore size of 3 nm was added to the aqueous solution and stirred with a stirrer for 30 minutes at room temperature. The activated carbon in the aqueous solution was then removed using filter paper (No. 2, manufactured by ADVANTEC Co., Ltd.) to obtain a catalyst for the production of polyurethane resin (the present invention). The odor of the catalyst and the amount of 2-ethylpyrazine contained in the catalyst were evaluated. The results are shown in Table 1. [Preparation of polyurethane resin] First, the following were prepared as Solution A and Solution B.

[0073] Solution A (polyol component): 100 parts by weight of polymer polyol (manufactured by Sanyo Chemical Industries, Ltd., product name "Sannix® FA-921"), 2 parts by weight of a connecting agent (manufactured by Toho Chemical Industry Co., Ltd., product name "Toho Polyol® QB-8000"), 2 parts by weight of a crosslinking agent (polyethylene glycol 200), 1 part by weight of a foam stabilizer (manufactured by Momentive Performance Materials, product name "Y-10366"), 2.2 parts by weight of a foaming agent (water), and 2.2 parts by weight of a catalyst for polyurethane resin production treated with activated carbon as described above were mixed to prepare Solution A (polyol component).

[0074] Solution B (polyisocyanate component): Polyisocyanate (manufactured by Tosoh Corporation, product name "CEF-456") was used as is.

[0075] The above-described solution A and an amount of solution B that results in an isocyanate index of 100 were mixed, and foaming was performed by mechanical stirring to obtain a polyurethane resin.

[0076] The odor of the polyurethane resin in question was evaluated. The results are shown in Table 1.

[0077] The evaluation and measurement results are shown in Table 1.

[0078] Comparative Examples 1-5 A catalyst for polyurethane resin production was prepared in the same manner as in Example 1, except that the pure water used in the [Preparation of Catalyst Composition] of Example 1 was replaced with the solvent shown in Table 1, and then a polyurethane resin was obtained. The odor of the catalyst and the polyurethane resin were evaluated, and the amount of 2-ethylpyrazine contained in the catalyst was quantitatively evaluated. The results are shown in Table 1.

[0079] [Table 1]

[0080] Items 1) to 5) in Table 1 are as follows:

[0081] 1) Ethylene glycol manufactured by Kishida Chemical Co., Ltd. 2) Dipropylene glycol manufactured by Kishida Chemical Co., Ltd. 3) Diethylene glycol manufactured by Kishida Chemical Co., Ltd. 4) Polyethylene glycol manufactured by Kishida Chemical Co., Ltd. 5) 2-methyl-1,3-propanediol manufactured by Tokyo Chemical Industry Co., Ltd. As is clear from the comparison between Example 1 and Comparative Examples 1-5, the 2-ethylpyrazine content could not be reduced with solvents other than pure water, and as a result, the effects of reducing the odor of the catalyst and the polyurethane resin could not be obtained.

[0082] Example 2 The experiment was carried out in the same manner as in Example 1, except that the activated carbon used in Example 1 was changed to Shirasagi A. The odor of the obtained catalyst was evaluated, the odor of the obtained polyurethane resin was evaluated, and the amount of 2-ethylpyrazine contained in the obtained catalyst was quantitatively evaluated. The results are shown in Table 2.

[0083] [Table 2]

[0084] Regarding item 1) in Table 2, it is as follows:

[0085] 1) Activated carbon powder manufactured by Osaka Gas Chemical Co., Ltd. Examples 3-5 The experiment was conducted in the same manner as in Example 1, except that the amount of activated carbon used in Example 1 (0.8 g, equivalent to 2% by weight of the aqueous solution) was changed to 0.4 g (equivalent to 21% by weight of the aqueous solution), 1.6 g (equivalent to 4% by weight of the aqueous solution), or 3.2 g (equivalent to 8% by weight of the aqueous solution). The odor of the obtained catalyst was evaluated, the odor of the obtained polyurethane resin was evaluated, and the amount of 2-ethylpyrazine contained in the obtained catalyst was quantitatively evaluated. The results are shown in Table 3.

[0086] [Table 3]

Claims

1. A catalyst for the production of polyurethane resin, comprising an aqueous solution of an amine compound (A) represented by the following general formula (1), wherein the concentration of the amine compound (A) in the aqueous solution is 35 to 65% by mass, and the 2-ethylpyrazine content in the aqueous solution is 0.3 ppm or more and 3.9 ppm or less. 【Chemistry 1】 [In the above general formula (1), R １ , R ２ , R ３ , R ４ and R ５ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a hydroxyl group, a hydroxymethyl group, or a C1-C4 alkoxy group. Each of a and b is independently 0 or 1, satisfying the relationship a + b = 1.

2. In the general formula (1), R １ , R ２ , R ３ , R ４ , and R ５ are each independently a hydrogen atom or a methyl group, and the catalyst for producing a polyurethane resin according to claim 1.

3. The catalyst for producing polyurethane resin according to claim 1 or 2, wherein the concentration of the amine compound (A) in the aqueous solution is 40 to 60% by mass.

4. A method for producing a polyurethane resin, characterized by reacting a polyol with a polyisocyanate in the presence of a catalyst for producing a polyurethane resin according to any one of claims 1 to 3.

5. A method for producing a catalyst for polyurethane resin according to any one of claims 1 to 3, comprising the following steps. Step 1: In the presence of an acid catalyst, the following general formula (2) 【Chemistry 2】 [In the above general formula (2), R １ , R ２ , R ３ , R ４ and R ５ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a hydroxyl group, a hydroxymethyl group, or a C1-C4 alkoxy group. The process involves intramolecular cyclization of a piperazine compound represented by the above general formula (1) to produce an amine compound represented by the above general formula (1), and then purifying the obtained amine compound by fractional distillation. Step 2: A step to produce an aqueous solution by dissolving the amine compound purified in Step 1 in water. Step 3: The aqueous solution obtained in Step 2 is brought into contact with activated carbon, and then the aqueous solution is isolated.

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