JP2008013485A - Alkanolamine, method for producing the same and method for producing polyurethane resin using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkanolamine, to provide a method for producing the alkanolamine and to provide a method for production by which a polyurethane resin using the alkanolamine can be obtained with good productivity and moldability. <P>SOLUTION: The polyurethane resin is produced by using the alkanolamine such as N,N'-bis(2-hydroxypropyl)-N,N'-diethylhexamethylenediamine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an alkanolamine, a method for producing the same, and a method for producing a polyurethane resin using the alkanolamine.

  The alkanolamine of the present invention is useful as an epoxy curing agent, urethane raw material, surfactant, fiber treatment agent, paper strength enhancer, resin modifier, lubricating oil additive, etc. It is extremely useful as a urethane raw material for producing a polyurethane resin or polyurethane foam having good moldability with high productivity.

  The polyurethane resin is produced by reacting a polyol and a polyisocyanate in the presence of a catalyst and, if necessary, a foaming agent, a surfactant, a flame retardant, a crosslinking agent and the like.

  In the production of polyurethane foam using water and / or a low-boiling organic compound as a blowing agent, tertiary amine compounds are widely used because of excellent productivity and moldability. Examples of such tertiary amine compounds include conventionally known triethylenediamine, bis (2-dimethylaminoethyl) ether, and the like. (For example, refer nonpatent literature 1). In most cases, the metal compound is often used in combination with a tertiary amine catalyst because the productivity and moldability are deteriorated, and the metal compound is rarely used alone.

  The above-mentioned tertiary amine catalyst is gradually discharged as a volatile amine from polyurethane products. For example, it is used in automobile interior materials and the like because it causes odor problems due to volatile amines and discoloration problems of other materials such as skin PVC. The amount is limited.

  As a method for solving this problem, instead of these volatile tertiary amine catalysts, amine catalysts having primary and secondary amino groups and hydroxyl groups capable of reacting with polyisocyanates in the molecule (hereinafter referred to as reactive catalysts). Have been proposed (see, for example, Patent Documents 1 and 2).

  The method using the above reactive catalyst is effective in avoiding the above problem because it is immobilized in the polyurethane resin skeleton in a form reacted with polyisocyanate, but the productivity and moldability of the polyurethane resin are reduced. Is a problem.

  As a method of solving this problem, a method of using a high molecular weight alkanolamine having a tertiary amino group in the molecule instead of these reactive catalysts has been proposed (for example, Patent Documents 3 to 4). reference).

  However, with tertiary amino alcohols preferred in Patent Document 3 and carboxylates of tertiary amino alcohols preferred in Patent Document 4, productivity in polyurethane resin production is low, and moldability is further improved. Since it deteriorated, it could not be said that it was industrially satisfactory.

Japanese Patent Publication No. 61-31727 Japanese Unexamined Patent Publication No. 63-265909 Japanese Patent No. 2756000 Japanese Patent No. 3262366 Keiji Iwata "Polyurethane Resin Handbook" (1987 first edition) Nikkan Kogyo Shimbun, p. 118

  The present invention has been made in view of the above problems, and the object thereof is an alkanolamine capable of improving productivity and moldability in polyurethane resin production in the method using the above-described reactive catalyst, and It is to provide a polyurethane resin using the same.

  The inventor has conducted extensive studies to solve the above problems. As a result, the alkanolamine of the present invention has been found to specifically and significantly improve the productivity and moldability in the production of polyurethane resins, and has led to the completion of the present invention.

  That is, this invention is an alkanolamine, its manufacturing method, and the manufacturing method of a polyurethane resin using the same as shown below.

  [1] An alkanolamine represented by the following general formula (1):

［上記式中、Ｒ_１、Ｒ_２は各々独立して下記一般式（２）

[In the above formula, R ₁ and R ₂ are each independently represented by the following general formula (2)

（上記式中、Ｒ_３、Ｒ_４は各々独立して水素原子、又は炭素数１〜２のアルキル基を表し、ｐは１〜２の整数を表す。）
で示される置換基を表す。］
［２］Ｎ，Ｎ’−ビス（２−ヒドロキシプロピル）−Ｎ，Ｎ’−ジエチルヘキサメチレンジアミン。

(In the above formula, R ₃ and R ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and p represents an integer of 1 to 2).
The substituent shown by is represented. ]
[2] N, N′-bis (2-hydroxypropyl) -N, N′-diethylhexamethylenediamine.

  [3] The method for producing an alkanolamine according to the above [1], wherein N, N′-diethylaminohexane is oxyalkylated with an alkylene oxide having 2 to 4 carbon atoms.

  [4] The alkylene oxide having 2 to 4 carbon atoms is one or more selected from the group consisting of ethylene oxide, 1,2-propylene oxide and 1,2-butylene oxide. [3] The method for producing an alkanolamine according to [3].

  [5] A process for producing N, N′-bis (2-hydroxypropyl) -N, N′-diethylhexamethylenediamine, characterized by oxyalkylating N, N′-diethylaminohexane with propylene oxide.

  [6] A method for producing a polyurethane resin, comprising reacting a polyol and an isocyanate in the presence of an alkanolamine represented by the general formula (1).

  [7] A method for producing a polyurethane resin, comprising reacting a polyol and an isocyanate in the presence of N, N′-bis (2-hydroxypropyl) -N, N′-diethylhexamethylenediamine.

In the general formula (1), R ₁ and R ₂ each independently represent a substituent represented by the general formula (2). Moreover, in the said General formula (1), carbon number of the alkylene chain between N and N 'nitrogen atoms is six. When the carbon number is less than 6, the moldability of the urethane resin may be lowered, and when the carbon number is larger than 6, the productivity of the urethane resin may be lowered. It is important that the substituent on the N, N ′ nitrogen atom is an ethyl group having 2 carbon atoms in order to improve the productivity and moldability of the urethane resin. When the number of carbon atoms is 1, the moldability is lowered. When the number of carbon atoms is greater than 2, the moldability is good but the productivity is lowered.

In the said General formula (2), R < ₃ >, R < ₄ > respectively independently represents a hydrogen atom or a C1-C2 alkyl group, and p value is an integer of 1-2. In view of ease of synthesis and production cost, R ₃ is preferably a hydrogen atom and R ₄ is preferably a methyl group. The p value is preferably 1 in terms of ease of synthesis and urethane resin productivity.

  The alkanolamine represented by the general formula (1) of the present invention can be easily produced by methods known in the literature.

  For example, it can be produced by adding an alkylene oxide to the active hydrogen site of N, N′-diethylaminohexane. N, N'-diethylaminohexane is commercially available and easily available.

  In the method of the present invention, the alkylene oxide is not particularly limited, and examples thereof include ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide and the like.

  Examples of the alkanolamine produced by the method of the present invention include N, N′-bis (2-hydroxyethyl) -N, N′-diethylhexamethylenediamine and N, N′-bis (2-hydroxypropyl). -N, N'-diethylhexamethylenediamine, N, N'-bis (2-hydroxybutyl) -N, N'-diethylhexamethylenediamine and the like. Further, these alkanolamines may further contain alkanolamines that have been reacted with alkylene oxide to increase the molecular weight in an arbitrary ratio.

  The alkanolamine of the present invention can be produced by reacting a polyol and a polyisocyanate in the presence of other foaming agents, surfactants, flame retardants, crosslinking agents, catalysts, etc., if necessary. Used as part of a crosslinking agent. When the alkanolamine of the present invention is used for producing a polyurethane resin, the amount used is usually in the range of 0.1 to 30 parts by weight, preferably 0.1 to 15 parts by weight, based on 100 parts by weight of the polyol. It is. More preferably, it is the range of 0.1-10 weight part. If the amount used is large, the polyurethane resin becomes too hard, which is disadvantageous in terms of cost.

  The method for producing a polyurethane resin of the present invention is characterized in that a polyol and an isocyanate are reacted in the presence of the alkanolamine of the present invention described above. In the method for producing a polyurethane resin of the present invention, a polyurethane foam can be produced by further reacting a polyol and an isocyanate in the presence of a foaming agent.

  Examples of other polyols used in the method for producing a polyurethane resin of the present invention include conventionally known polyether polyols, polyester polyols, polymer polyols, and flame retardant polyols such as phosphorus-containing polyols and halogen-containing polyols. Can be mentioned. These polyols can be used alone or in combination as appropriate.

  Examples of the polyether polyol include at least two of polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, trimethylolpropane, and pentaerythritol, amines such as ethylenediamine, and alkanolamines such as ethanolamine and diethanolamine. The compound having the above active hydrogen group is used as a starting material, and is produced by addition reaction of this with an alkylene oxide such as ethylene oxide or propylene oxide [for example, Gunter Oeltel, “Polyurethane Handbook” (1985 edition) Hanser Publishers (Germany) p. See 42-53 etc. ].

  Polyester polyols can be obtained from the dehydration condensation reaction of dibasic acids (mainly adipic acid) with glycols and triols, wastes from the production of nylon, trimethylolpropane, pentaerythritol wastes, and phthalic polyester wastes. And polyester polyols obtained by treating waste products [for example, Keiji Iwata “Polyurethane Resin Handbook” (first edition in 1987), Nikkan Kogyo Shimbun, p. See 117 etc. ].

  Examples of the polymer polyol include a polymer polyol obtained by reacting the polyether polyol and an ethylenically unsaturated monomer (for example, butadiene, acrylonitrile, styrene, etc.) in the presence of a radical polymerization catalyst.

  Examples of the flame retardant polyol include phosphorus-containing polyols obtained by adding alkylene oxide to a phosphoric acid compound, halogen-containing polyols obtained by ring-opening polymerization of epichlorohydrin and trichlorobutylene oxide, and phenol polyols.

  These polyols can have an average hydroxyl value of about 20 to 1000 mg KOH / g, but 20 to 100 mg KOH / g for flexible polyurethane foam and semi-rigid polyurethane foam products, and 100 to 800 mg KOH for spray type rigid polyurethane foam. / G is preferably used.

  The polyisocyanate used in the method for producing a polyurethane resin of the present invention includes toluene diisocyanate (hereinafter sometimes referred to as TDI), diphenylmethane diisocyanate (hereinafter sometimes referred to as MDI), naphthylene diisocyanate, and xylylene diene. Examples thereof include aromatic polyisocyanates such as isocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as dicyclohexyl diisocyanate and isophorone diisocyanate, and mixtures thereof. Among these, TDI and its derivatives or MDI and its derivatives are preferable, and these may be used in combination.

  Examples of TDI and its derivatives include a mixture of 2,4-TDI and 2,6-TDI or a terminal isocyanate prepolymer derivative of TDI. Examples of MDI and its derivatives include a mixture of MDI and its polymer polyphenyl polymethylene diisocyanate, and / or a diphenylmethane diisocyanate derivative having a terminal isocyanate group.

  Among these isocyanates, flexible polyurethane foam and semi-rigid polyurethane foam products include TDI and derivatives thereof, or MDI and derivatives thereof, and mixtures thereof, and spray-type rigid polyurethane foams include MDI and its polymer polyphenylpolymethylene diisocyanate. The mixture of is preferably used.

  The mixing ratio of these polyisocyanates and polyols is not particularly limited, but is usually in the range of 60 to 400 in terms of isocyanate index (isocyanate groups / active hydrogen groups capable of reacting with isocyanate groups).

  Examples of usable catalysts in the method for producing a polyurethane resin of the present invention include organometallic catalysts, carboxylic acid metal salts, tertiary amines and quaternary ammonium salts.

  The organometallic catalyst is a metal compound other than lead, tin, and mercury, and may be any conventionally known compound, and is not particularly limited. For example, bismuth octoate, bismuth neodecanoate, zinc octoate, Preferred examples include zinc neodecanoate, zinc naphthenate, nickel octoate, nickel naphthenate, cobalt naphthenate and the like. Heavy metals such as lead, tin and mercury cause toxicity problems and environmental problems, so it is desirable to use less.

  The carboxylic acid metal salt is not particularly limited as long as it is a conventionally known metal salt, and examples thereof include alkali metal salts and alkaline earth metal salts of carboxylic acids. The carboxylic acid is not particularly limited, but examples thereof include aliphatic mono- and dicarboxylic acids such as acetic acid, propionic acid, 2-ethylhexanoic acid and adipic acid, and aromatic mono- and dicarboxylic acids such as benzoic acid and phthalic acid. Etc. Moreover, as a metal which should form carboxylate, alkaline earth metals, such as alkali metals, such as lithium, sodium, and potassium, and calcium, magnesium, are mentioned as a suitable example.

  The tertiary amines may be any conventionally known ones and are not particularly limited. For example, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ′ can be used. -Tetramethylpropylenediamine, N, N, N ', N ", N" -pentamethyldiethylenetriamine, N, N, N', N ", N" -pentamethyl- (3-aminopropyl) ethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldipropylenetriamine, N, N, N ′, N′-tetramethylguanidine, 1,3,5-tris (N, N-dimethylaminopropyl) hexahydro-S-triazine 1,8-diazabicyclo [5.4.0] undecene-7, triethylenediamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N′-dimethyl Perazine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, bis (2-dimethylaminoethyl) ether, 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, 1-dimethyl There may be mentioned tertiary amine compounds such as aminopropylimidazole.

  The quaternary ammonium salts are not particularly limited as long as they are conventionally known. For example, tetraalkylammonium halides such as tetramethylammonium chloride, tetraalkylammonium salts such as tetramethylammonium hydroxide salts, and the like. Examples thereof include tetraalkylammonium organic acid salts such as hydroxide, tetramethylammonium 2-ethylhexanoate, 2-hydroxypropyltrimethylammonium formate, and 2-hydroxypropyltrimethylammonium 2-ethylhexanoate.

  Of these catalysts, tertiary amines are preferred as other catalysts used in combination with the alkanolamines of the present invention. Of the tertiary amines, triethylenediamine and bis (dimethylaminoethyl) ether are particularly preferred.

  In the method for producing a polyurethane resin of the present invention, the amount of the catalyst used is usually 0.01 to 20 parts by weight, preferably 0.05 to 10 parts by weight, based on 100 parts by weight of the polyol used. . If it is less than 0.01 part by weight, the polyurethane resin is slowly cured and the moldability is deteriorated. On the other hand, if it exceeds 20 parts by weight, not only the effect of increasing the catalyst is not obtained, but also the moldability may be deteriorated.

  Specifically as a foaming agent used for the manufacturing method of the polyurethane resin of this invention, a fluorocarbon compound, a low boiling point hydrocarbon, water, and mixtures thereof are mentioned. Examples of fluorocarbon compounds include dichloromonofluoroethane (HCFC-141b), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3-pentafluorobutane (HFC). -365mfc) and the like, but from the problem of ozone layer destruction, 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3-pentafluorobutane (HFC) -365mfc) is preferred. As the low-boiling hydrocarbons, hydrocarbons having a boiling point of 0 to 70 ° C. are usually used, and specific examples include propane, butane, pentane, cyclopentane, hexane, and mixtures thereof. Of these foaming agents, water is particularly preferred.

  In the method for producing a polyurethane resin of the present invention, a surfactant can be used as a foam stabilizer if necessary. Examples of the surfactant to be used include conventionally known organosilicone surfactants, and specifically, nonionic systems such as organosiloxane-polyoxyalkylene copolymers and silicone-grease copolymers. Surfactant or a mixture thereof is exemplified. Their use amount is usually 0.1 to 10 parts by weight per 100 parts by weight of polyol.

  In the method for producing a polyurethane resin of the present invention, a crosslinking agent or a chain extender can be used if necessary. Examples of the crosslinking agent or chain extender include low molecular weight polyhydric alcohols such as ethylene glycol, 1,4-butanediol and glycerin, low molecular weight amine polyols such as diethanolamine and triethanolamine, or ethylenediamine and xylylene. Examples include polyamines such as range amine and methylene bisorthochloroaniline.

  In the method for producing a polyurethane resin of the present invention, a flame retardant can be used if necessary. Examples of the flame retardant used include reactive flame retardants such as phosphorus-containing polyols such as propoxylated phosphoric acid and propoxylated dibutyl pyrophosphate obtained by addition reaction of phosphoric acid and alkylene oxide, tricresyl Tertiary phosphates such as phosphate, halogen-containing tertiary phosphates such as tris (2-chloroethyl) phosphate, tris (chloropropyl) phosphate, halogens such as dibromopropanol, dibromoneopentyl glycol, tetrabromobisphenol A Examples include organic compounds, inorganic compounds such as antimony oxide, magnesium carbonate, calcium carbonate, and aluminum phosphate. The amount is not particularly limited, and is usually 4 to 20 parts by weight with respect to 100 parts by weight of polyol, although it varies depending on the required flame retardancy.

  In the method for producing a polyurethane resin of the present invention, a colorant, an antiaging agent, and other conventionally known additives can be used as necessary. The type and amount of these additives may be within the normal usage range of the additive used.

  The method for producing the polyurethane resin of the present invention is carried out by rapidly mixing and stirring the mixed solution in which the raw materials are mixed, and then injecting the mixture into a suitable container or mold to perform foam molding. Mixing and stirring may be performed using a general stirrer or a dedicated polyurethane foaming machine. As the polyurethane foaming machine, high-pressure, low-pressure and spray-type devices can be used.

  Examples of polyurethane resin products include elastomers that do not use a foaming agent and polyurethane foams that use a foaming agent. Among them, the production of polyurethane foam products is preferred. Polyurethane foam products include soft, semi-rigid, rigid, etc. Especially, heat insulation manufactured with soft car seats, semi-rigid instrument panels and handles used as automotive interior materials, and spray-type rigid foam. Building materials are preferred.

  Hereinafter, although demonstrated based on an Example, this invention is not limited only to these Examples.

Example 1
In a 200 ml autoclave with a stirrer, 52 g of N, N′-diethyl-1,6-diaminohexane (manufactured by Tokyo Chemical Industry Co., Ltd.) was charged. The autoclave was sealed and purged with nitrogen, and then heated to 120 ° C. with stirring. Subsequently, 38.6 g of propylene oxide was pumped over 1 hour. After aging reaction for 2 hours, the pressure was reduced at 100 ° C./8 KPa to remove unreacted propylene oxide, and then the reaction solution was taken out by cooling and N, N′-bis (2-hydroxyethyl) -N , 87 'of N'-diethylhexamethylenediamine was obtained.

The results of ¹ H-NMR measurement in a CD ₃ OD solvent are shown below.

  δ1.1 (t) 6H, δ1.2 (d) 6H, δ1.4-1.7 (m) 8H, δ2.5-2.8 (m) 12H, δ3.9 (m) 2H.

Examples 2 to 4 and Comparative Examples 1 to 4
As an example of producing a semi-rigid polyurethane foam using the alkanolamine of the present invention, a comparative example of producing a semi-rigid polyurethane foam using various crosslinking agents and catalysts instead of not using the alkanolamine of the present invention was compared. An example is shown below.

  Premix A was prepared at the raw material mixing ratio shown in Table 1.

１）ＦＡ７０３、三洋化成社製ポリエーテルポリオール
２）イソシアネート（ＭＤＩ）：ＭＲ２００（日本ポリウレタン社製）
３）ＩＮＤＥＸ＝（ＮＣＯ基モル数／ＯＨ基モル数）×１００。

1) FA703, polyether polyol manufactured by Sanyo Kasei Co., Ltd. 2) Isocyanate (MDI): MR200 (manufactured by Nippon Polyurethane Co., Ltd.)
3) INDEX = (number of moles of NCO group / number of moles of OH group) × 100.

  Take 102.8 g of Premix A in a 300 ml polyethylene cup, add the alkanolamine of the present invention or various catalysts shown in Table 2 in such an amount that the reactivity becomes 70 seconds with the following gel times, respectively, and adjust the temperature to 23 ° C. . Put the isocyanate liquid whose temperature was adjusted to 23 ° C. in a separate container into the premix A cup in such an amount that the isocyanate index [= isocyanate group / OH group (molar ratio) × 100)] is 105, and quickly use a stirrer. Stir at 6000 rpm for 5 seconds. The mixed and stirred liquid mixture was transferred to a 2 liter polyethylene cup whose temperature was adjusted to 40 ° C., and the reactivity during foaming was measured.

Next, the liquid mixture is put in a mold (inner dimensions, 295 × 305 × 25 mm aluminum) whose temperature is adjusted to 40 ° C. so that the total foam density becomes 100 kg / m ³ by the same operation, and the lid is put on. Foam molding was performed. The foam was demolded 11 minutes after the start of mixing, and the foam hardness at the time of demolding was measured 1 minute later. In addition, the foam hardness was measured and compared from the molded foam. The results are shown in Table 2. The measurement method for each measurement item is as follows.

(1) Reactive measurement items Cream time: Measure foaming start time, foam start time visually. Gel time: Measure time when reaction progresses and change from liquid to resinous material. Rise time: Foam rise Visually measure the time to stop.

(2) Hardness at the time of demolding The foam was demolded 11 minutes after the start of mixing, and after 1 minute, the demolding hardness of the foam was measured with a SHORE-C hardness meter.

(3) Hardness of foam The foam was demolded 11 minutes after the start of mixing, and the hardness of the foam was measured 24 hours later with a SHORE-C hardness meter.

(4) Formability of foam The foam was demolded 11 minutes after the start of mixing, the appearance of the foam was observed 24 hours later, and the presence or absence of voids on the front and back surfaces was visually confirmed. Those having no voids on the front surface and / or the back surface can be said to have good moldability.

１）Ｎ，Ｎ’−ビス（２−ヒドロキシプロピル）−Ｎ，Ｎ’−ジエチルヘキサメチレンジアミン（合成品）
２）トリエチレンジアミン３３．３％、ジプロピレングリコール６６．７％溶液（東ソー（株）社製ＴＥＤＡ−Ｌ３３）とビス（ジメチルアミノエチル）エーテル７０％、ジプロピレングリコール３０％（東ソー（株）社製ＴＯＹＯＣＡＴ−ＥＴ）の８０：２０（重量比）の混合液
３）下記一般式（３）で表されるメチルアミンと１，６−ヘキサンジオールの縮合物。

1) N, N′-bis (2-hydroxypropyl) -N, N′-diethylhexamethylenediamine (synthetic product)
2) Triethylenediamine 33.3%, dipropylene glycol 66.7% solution (TEDA-L33 manufactured by Tosoh Corporation) and bis (dimethylaminoethyl) ether 70%, dipropylene glycol 30% (Tosoh Corporation) 80:20 (weight ratio) mixed solution of TOYOCAT-ET) 3) Condensation product of methylamine and 1,6-hexanediol represented by the following general formula (3).

（式中、ｎは平均重合度２．７を表す）
４）上記一般式（３）で示されるメチルアミンと１，６−ヘキサンジオールの縮合物の蟻酸塩（モル比１：１）。

(Where n represents an average degree of polymerization of 2.7)
4) Formate salt of a condensate of methylamine and 1,6-hexanediol represented by the general formula (3) (molar ratio 1: 1).

  Examples 2 to 4 are examples using the alkanolamine of the present invention. As is clear from the above table, the obtained polyurethane foam has high hardness at the time of demolding, that is, high productivity, and moldability of the foam. Is also good.

On the other hand, Comparative Example 1 is an example using only a general-purpose tertiary amine catalyst, but the polyurethane foam obtained has a low hardness at the time of demolding. Comparative Example 2 and Comparative Example 3 are examples in which a condensate of methylamine and 1,6-hexanediol and a formate of a condensate of methylamine and 1,6-hexanediol were used. Foam moldability is poor at the time of demolding and foam hardness is low.

Claims (7)

An alkanolamine represented by the following general formula (1):

[In the above formula, R ₁ and R ₂ are each independently represented by the following general formula (2)

(In the above formula, R ₃ and R ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and p represents an integer of 1 to 2).
The substituent shown by is represented. ]   N, N'-bis (2-hydroxypropyl) -N, N'-diethylhexamethylenediamine.   The method for producing alkanolamine according to claim 1, wherein N, N'-diethylaminohexane is oxyalkylated with an alkylene oxide having 2 to 4 carbon atoms.   The alkylene oxide having 2 to 4 carbon atoms is one or more selected from the group consisting of ethylene oxide, 1,2-propylene oxide and 1,2-butylene oxide. The production method of alkanolamine.   A process for producing N, N'-bis (2-hydroxypropyl) -N, N'-diethylhexamethylenediamine, characterized in that N, N'-diethylaminohexane is oxyalkylated with propylene oxide.   A process for producing a polyurethane resin comprising reacting a polyol and an isocyanate in the presence of the alkanolamine according to claim 1. A process for producing a polyurethane resin, comprising reacting a polyol and an isocyanate in the presence of N, N'-bis (2-hydroxypropyl) -N, N'-diethylhexamethylenediamine.