Process for the preparation of a blowing catalyst and its use in high density, high strength polyurethane foams

Abstract

The application belongs to the field of organic synthesis, and particularly relates to a foaming catalyst, bis(3-ethoxypropyl)dimethylaminopropylamine and a preparation method thereof, and application of the bis(3-ethoxypropyl)dimethylaminopropylamine in preparation of high-density and high-strength polyurethane foam. 15 H 24 N2O2, a molecular weight is 274.26, and a structural formula is: The application also simultaneously provides application of the bis(3-ethoxypropyl)dimethylaminopropylamine as a foaming catalyst for preparing high-density and high-strength polyurethane foam. The bis(3-ethoxypropyl)dimethylaminopropylamine is used in a polyurethane foam formula, and polyurethane foam prepared by the bis(3-ethoxypropyl)dimethylaminopropylamine has the advantages of high density and high strength.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic synthesis, and particularly relates to a preparation method of a foaming catalyst, bis(3-ethoxypropyl)dimethylaminopropylamine, and application thereof in preparation of high-density and high-strength polyurethane foam. BACKGROUND

[0002] Polyurethane products have important application value in the fields of foam, fiber, rubber, elastomer, paint and adhesive, among which polyurethane foam accounts for a large proportion; in the production process of polyurethane foam, a foaming catalyst plays an important role, and its main function is to make the foaming system achieve ideal foaming and curing time, so as to obtain a product with excellent mechanical and physical properties. For example, a commercially used amine catalyst A33 (33% triethylene diamine solution, solvent is dipropylene glycol) has the advantage of high foaming activity, and can be used in many fields related to polyurethane materials, but with the development of society, the performance requirements of polyurethane foam materials are getting higher and higher, and such catalysts are increasingly difficult to meet the requirements.

[0003] A foaming catalyst in the prior art is tri(N,N-dimethylaminopropyl)amine, which has a CAS number of 33329-35-0, a molecular formula of C 15 H 36 N4 and a molecular weight of 272.47. The preparation method is to use 3-dimethylaminopropylamine and acrylonitrile as starting materials to prepare by Michael addition, catalytic hydrogenation and hydrogen methylation steps, and the polyurethane foam formula obtained by using the foaming catalyst is: PPG-2000, methane, flame retardant TPP, water, silicone oil 815H, stannous octoate, tri(N,N-dimethylaminopropyl)amine and TDI-80. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a preparation method of a foaming catalyst, bis(3-ethoxypropyl)dimethylaminopropylamine, for high-density and high-strength polyurethane foam and application thereof.

[0005] To solve the above technical problem, the present application provides bis(3-ethoxypropyl)dimethylaminopropylamine, which has a molecular formula of C 15 H 24 N2O2 and a molecular weight of 274.26, and a structural formula of:

[0006]

[0007] Formula 1, structural formula of bis(3-ethoxypropyl)dimethylaminopropylamine

[0008] The present application also provides a preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine, comprising the following steps:

[0009] 1) using acrylonitrile and bis(3-ethoxypropyl)amine as raw materials, dissolving bis(3-ethoxypropyl)amine in methanol to obtain a methanol solution of bis(3-ethoxypropyl)amine, heating to 20-100°C (preferably 40±10°C), then adding acrylonitrile dropwise into the methanol solution of bis(3-ethoxypropyl)amine for reaction, the dropwise adding time being 2-5h (preferably 3±0.5h), and continuing to heat for 1-4h (preferably 2±0.5h) after the dropwise adding is completed;

[0010] The molar ratio of bis(3-ethoxypropyl)amine: acrylonitrile is 1:(1±0.05); and the methanol is 50%-100% of the mass of bis(3-ethoxypropyl)amine;

[0011] Note: the methanol serves as both an addition catalyst and a solvent;

[0012] 2) transferring the reaction liquid obtained in step 1) (a reaction liquid containing bis(3-ethoxypropyl) cyanoethylamine) into an autoclave, adding a hydrogenation catalyst and an inhibitor into the autoclave, carrying out gas replacement (successively using inert gas and hydrogen) in the autoclave, then introducing hydrogen into the autoclave, and reacting under the conditions of hydrogen pressure 1.0-5.0MPa and reaction temperature 30-150°C for 4-10h (preferably 2-4MPa, 50-100°C, 3-6h);

[0013] The hydrogenation catalyst is 1%-20% (preferably 5-10%) of the mass of bis(3-ethoxypropyl)amine in step 1), and the inhibitor is 0%-10% (preferably 0.1%-5%, more preferably 0.4-0.6%, and more preferably 0.5%) of the mass of bis(3-ethoxypropyl)amine in step 1);

[0014] 3) adding paraformaldehyde into the reaction liquid obtained in step 2) (a reaction liquid containing bis(3-ethoxypropyl) aminopropylamine) in the autoclave, carrying out gas replacement (successively using inert gas and hydrogen) in the autoclave, then introducing hydrogen into the autoclave, and reacting under the conditions of hydrogen pressure 1.0-5.0MPa and reaction temperature 30-150°C for 4-10h;

[0015] The molar ratio of paraformaldehyde: acrylonitrile in step 1) is 2.0-3.0:1;

[0016] The reaction product is subjected to post-treatment to obtain bis(3-ethoxypropyl) dimethylaminopropylamine.

[0017] Description: This step 3), with bis (3-methoxy propyl) aminopropylamine and paraformaldehyde as raw materials, in the presence of methanol solvent and hydrogenation catalyst, catalytic hydrogenation methylation, prepared bis (3-ethoxy propyl) dimethyl aminopropylamine.

[0018] As an improvement of the preparation method of bis (3-ethoxy propyl) dimethyl aminopropylamine of the present application, the step 2):

[0019] The inhibitor is an inorganic base;

[0020] The hydrogenation catalyst is any of the following: Raney Ni, Raney Co, Pd / C (5wt% Pd), Pt / C (5wt% Pt).

[0021] As a further improvement of the preparation method of bis (3-ethoxy propyl) dimethyl aminopropylamine of the present application, the inorganic base is any of the following: sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium methoxide, sodium ethoxide.

[0022] As a further improvement of the preparation method of bis (3-ethoxy propyl) dimethyl aminopropylamine of the present application: after the post-treatment of step 3), the hydrogenation catalyst and methanol can be recycled.

[0023] As a further improvement of the preparation method of bis (3-ethoxy propyl) dimethyl aminopropylamine of the present application: the post-treatment of step 3) is: emptying the autoclave gas, then opening the autoclave and standing, filtering, respectively obtaining filtrate and filter cake, the filtrate is the reaction solution containing bis (3-ethoxy propyl) dimethyl aminopropylamine; the filter cake is the hydrogenation catalyst;

[0024] The hydrogenation catalyst can be recovered after washing and used in circulation;

[0025] The filtrate is subjected to vacuum rectification to obtain methanol fraction and bis (3-ethoxy propyl) dimethyl aminopropylamine.

[0026] As a further improvement of the preparation method of bis (3-ethoxy propyl) dimethyl aminopropylamine of the present application:

[0027] The recovered hydrogenation catalyst can be recycled for step 2), and since the amount of catalyst is lost during the recovery process, new hydrogenation catalyst needs to be supplemented when the hydrogenation catalyst is recycled, and the amount of supplement is about 5% to 10% of the set amount (original amount) of hydrogenation catalyst;

[0028] The recovered methanol can be recycled for step 1), and since the amount of methanol is lost during the recovery process, new methanol needs to be supplemented when the methanol is recycled, and the amount of supplement is about 5% to 10% of the set amount.

[0029] The application also simultaneously provides the use of bis(3-ethoxypropyl)dimethylaminopropylamine as a foaming catalyst for preparing polyurethane foam (high-density, high-strength polyurethane foam).

[0030] The application also simultaneously provides a polyurethane foam (high-density, high-strength polyurethane foam): the polyurethane foam formula is composed of the following components in mass parts:

[0031] 75-85 parts of PTMEG-1000, 8-12 parts of HFC-245fa, 8-12 parts of ammonium polyphosphate, 2-4 parts of water, 0.5-1.5 parts of silicone oil 815H, 0.2-0.4 parts of stannous octoate, 0.1-0.2 parts of dibutyltin dilaurate, 0.3-0.7 parts of an amine catalyst, which is bis(3-ethoxypropyl)dimethylaminopropylamine, and 55-65 parts of TDI-80.

[0032] The synthetic route of the application is as follows in formula 2:

[0033]

[0034] The synthetic route of bis(3-ethoxypropyl)dimethylaminopropylamine in formula 2

[0035] The application aims to synthesize high-density, high-strength polyurethane foam. Since the existing A33 type catalyst is a stereoscopic catalyst, chain transfer may occur during catalytic foaming reaction, which is not conducive to the synthesis of high-crosslinking-density polyurethane foam. Considering that methoxy, ethoxy and other groups have good catalytic activity and good ether bond end group compatibility, compared with the structurally similar tri(N,N-dimethylaminopropyl)amine, the foaming reaction catalyzed by the foaming catalyst containing the structure of the application, bis(3-ethoxypropyl)dimethylaminopropylamine, can obtain high-crosslinking-density and high-strength products. Therefore, the application innovatively designs a compound, bis(3-ethoxypropyl)dimethylaminopropylamine, according to the characteristics of the groups of the raw materials, and develops a corresponding process route, and it is proved by application that the compound, bis(3-ethoxypropyl)dimethylaminopropylamine, is a foaming catalyst for preparing high-density, high-strength polyurethane foam.

[0036] In summary, the application proposes to use existing bis(3-ethoxypropyl)amine and acrylonitrile as raw materials to prepare a polyurethane foaming catalyst, bis(3-ethoxypropyl)dimethylaminopropylamine, which can be used for synthesizing high-density, high-strength polyurethane foam, through the steps of Michael addition, catalytic hydrogenation and hydrogen methylation. The bis(3-ethoxypropyl)dimethylaminopropylamine of the application is a good polyurethane foaming catalyst, and the synthesized polyurethane foam has the advantages of high density and high strength, and the synthesis method has not been reported in the literature.

[0037] The raw material used in the application, bis (3-ethoxypropyl) amine, has a molecular formula of C 10 H 23 NO2, CAS No. 19235-38-2, and its synthesis method can refer to the existing patent CN117209385A of the applicant.

[0038] The application has the following technical advantages:

[0039] 1. In step 2), by selecting appropriate inhibitors, a small amount of inhibitors can be used to obtain primary amines with high selectivity, effectively preventing disulfide side reactions; and the hydrogenation reaction solution can be continuously subjected to the next N-methylation reaction, reducing the operation steps.

[0040] 2. Methanol and hydrogenation catalysts can be recycled and reused, reducing production costs.

[0041] 3. The bis (3-ethoxypropyl) dimethylaminopropyl amine described in the application is used in polyurethane foam formulations, and the polyurethane foam obtained has the advantages of high density and high strength.

[0042] In summary, the application has the characteristics of simple process, low production cost and excellent product performance, and therefore has good application prospects and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0043] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0044] Figure 1 The bis (3-ethoxypropyl) dimethylaminopropyl amine is 1 H NMR spectrum. DETAILED DESCRIPTION

[0045] The application will be further described below in conjunction with specific examples, but the scope of protection of the application is not limited thereto:

[0046] Steps 1) to 3) of the application are all carried out under conventional stirring conditions.

[0047] Example 1, a preparation method of bis (3-ethoxypropyl) dimethylaminopropyl amine, the following steps are carried out in turn:

[0048] 1. 378.3g (2.0mol) bis (3-ethoxypropyl) amine was put into a reaction kettle, and 189.2g methanol was added thereto. After stirring and mixing, the temperature was raised to 40℃, and 106.1g (2.0mol) acrylonitrile was added dropwise into the reaction kettle within 3h. After the dropwise addition of acrylonitrile was completed, stirring was maintained and the reaction was maintained for 2h, obtaining a reaction solution containing bis (3-ethoxypropyl) cyanoethyl amine.

[0049] 2) Transfer the whole reaction solution obtained in step 1) into an autoclave, add 18.9 g of Raney Ni catalyst (as a hydrogenation catalyst) and 1.9 g of potassium hydroxide (as an inhibitor). Then close the autoclave, replace the gas in the autoclave with nitrogen for 3 times, replace the gas in the autoclave with hydrogen for 3 times, after the replacement is completed, charge the autoclave with hydrogen to an initial pressure of 1.5 MPa, after the temperature is raised to a reaction temperature of 50°C, supplement hydrogen to a pressure of 2.0 MPa, then keep the pressure constant, and react at 50°C. The reaction time is 6 h. After the reaction is completed, the autoclave is cooled to room temperature, and the gas in the autoclave is discharged. A reaction solution containing bis(3-ethoxypropyl)aminopropylamine is obtained.

[0050] 3) Add 120 g (4.0 mol) of polyformaldehyde to the reaction solution containing bis(3-ethoxypropyl)aminopropylamine obtained in step 2) in the autoclave, then close the autoclave, replace the gas in the autoclave with nitrogen for 3 times, replace the gas in the autoclave with hydrogen for 3 times, after the replacement is completed, charge the autoclave with hydrogen to an initial pressure of 1.5 MPa, slowly raise the temperature to a reaction temperature of 80°C, supplement hydrogen to a pressure of 2.0 MPa, then keep the pressure constant, and react at 80°C. The reaction time is 5 h. A reaction solution containing bis(3-ethoxypropyl)dimethylaminopropylamine is obtained.

[0051] After the reaction is completed, the autoclave is cooled and the gas in the autoclave is discharged. After the autoclave is opened and left to stand for 1 h, filtration is performed. The filtrate and the filter cake are obtained, respectively. The filtrate is a reaction solution containing bis(3-ethoxypropyl)dimethylaminopropylamine; and the filter cake is Raney Ni catalyst.

[0052] The filter cake is washed with methanol for 3 times and recovered, and can be used as a catalyst for recycling;

[0053] The filtrate is rectified. The methanol fraction at 65°C is collected under normal pressure, and the fraction at 140°C is collected under reduced pressure at a pressure of 300 Pa, which is bis(3-ethoxypropyl)dimethylaminopropylamine.

[0054] 465 g of bis(3-ethoxypropyl)dimethylaminopropylamine with a purity of 99.5% is obtained as a product, and the yield of the final product is 84.8%. 180 g of methanol is recovered, and 18 g of Raney Ni catalyst is recovered.

[0055] Product yield = the amount of bis(3-ethoxypropyl)dimethylaminopropylamine actually obtained by rectification / the amount of bis(3-ethoxypropyl)dimethylaminopropylamine obtained theoretically.

[0056] Bis(3-ethoxypropyl)dimethylaminopropylamine, with a molecular formula of C 15 H 24 N2O2, a molecular weight of 274.26, and a structural formula of:

[0057]

[0058] 1 H NMR spectrum is as shown in Figure 1 .

[0059] Example 2-1, the following changes are made relative to Example 1:

[0060] The catalyst in Step 2) is changed from Raney Ni to Pd / C (5 wt% Pd) with the weight remaining unchanged at 18.9 g; the rest is identical to Example 1.

[0061] The resulting bis(3-ethoxypropyl)dimethylaminopropylamine product yield is 50.9%.

[0062] Example 2-2, the following changes are made relative to Example 1:

[0063] The catalyst in Step 2) is changed from Raney Ni to Pt / C (5 wt% Pt) with the weight remaining unchanged at 18.9 g; the rest is identical to Example 1.

[0064] The resulting bis(3-ethoxypropyl)dimethylaminopropylamine product yield is 46.7%.

[0065] Example 2-3, the following changes are made relative to Example 1:

[0066] The catalyst in Step 2) is changed from Raney Ni to Raney Co with the weight remaining unchanged at 18.9 g; the rest is identical to Example 1.

[0067] The resulting bis(3-ethoxypropyl)dimethylaminopropylamine product yield is 65.3%.

[0068] Example 3, the following changes are made relative to Example 1:

[0069] The amount of catalyst in Step 2) is changed from 18.9 g to 37.8 g; the rest is identical to Example 1.

[0070] The resulting bis(3-ethoxypropyl)dimethylaminopropylamine product yield is 82.2%.

[0071] Example 4, the following changes are made relative to Example 1:

[0072] The reaction pressure in Step 2) is changed from 2.0 MPa to 4.0 MPa and the reaction time is changed to 5 h; and the reaction pressure in Step 3) is changed from 2.0 MPa to 4.0 MPa and the reaction time is changed to 4 h; the rest is identical to Example 1.

[0073] The product bis(3-ethoxypropyl)dimethylaminopropylamine was obtained in a yield of 85.5%.

[0074] Example 5, the following changes were made relative to Example 1:

[0075] The reaction temperature of Step 2) was changed from 50°C to 100°C, and the reaction time was changed to 3h; the reaction temperature of Step 3) was changed from 80°C to 120°C, and the reaction time was changed to 2.5h; the rest was the same as Example 1.

[0076] The product bis(3-ethoxypropyl)dimethylaminopropylamine was obtained in a yield of 79.4%.

[0077] Example 6, the amount of methanol in Example 1 was changed from 189.2g to 378.3g, and the rest was the same as Example 1.

[0078] The product bis(3-ethoxypropyl)dimethylaminopropylamine was obtained in a yield of 85.2%.

[0079] Example 7, recycling:

[0080] Relative to Example 1, the "18.9g Raney Ni catalyst" in Step 2) was changed to "18g of Raney Ni catalyst recovered from Example 1 Step 3) and supplemented with 0.9g of fresh Raney Ni catalyst". The rest was the same as Example 1. This is the first recovery corresponding to recycling;

[0081] By analogy, the fresh Raney Ni catalyst was supplemented to the recovered Raney Ni catalyst until the total weight was 18.9g, which was used as the catalyst. This is the second recovery corresponding to recycling;

[0082] The corresponding relationship between the number of times the catalyst was recycled and the results obtained is shown in Table 1.

[0083] Table 1, experimental results when the number of times the hydrogenation catalyst was recycled was different

[0084]

[0085] Comparative Example 1-1, the following changes were made relative to Example 1:

[0086] The amount of inhibitor potassium hydroxide in Step 2) was changed from 0.5% to 0; the rest was the same as Example 1.

[0087] The product bis(3-ethoxypropyl)dimethylaminopropylamine was obtained in a yield of 75.4%.

[0088] Comparative Example 1-2, the following changes were made relative to Example 1:

[0089] The amount of inhibitor potassium hydroxide in step 2) is changed from 0.5% to 5%; the rest is the same as example 1.

[0090] The yield of the product bis(3-ethoxypropyl)dimethylaminopropylamine obtained in step 3) is 62.8%.

[0091] Experiment two, using bis(3-ethoxypropyl)dimethylaminopropylamine as an amine catalyst for preparing high-density, high-strength polyurethane foam, as follows:

[0092] According to the mass fraction, 80 parts of PTMEG-1000 (polytetrahydrofuran ether glycol), 10 parts of HFC-245fa, 10 parts of ammonium polyphosphate, 3 parts of water, 1 part of silicone oil 815H, 0.3 parts of stannous octoate, 0.15 parts of dibutyltin dilaurate, and 0.5 parts of amine catalyst are sequentially added to a mixing barrel, mixed and stirred by a stirrer with a rotation speed of 3000 r / min for 10 s, and then statically placed for 1 min. Then, 60 parts of toluene diisocyanate (TDI-80) with a 2,4-isomer content of 80% is poured into a mold, the temperature is controlled at room temperature, and the timing is started. After rapid stirring for 3 s, the mixture is poured into a foaming box for foaming. After curing, it is cut into the required size for performance testing.

[0093] Under the same experimental conditions, the foaming effects of three amine catalysts are compared: ① A33 (33% content of triethylene diamine solution, solvent is dipropylene glycol), which is a commonly used amine catalyst in commerce; ② tri(N,N-dimethylaminopropyl)amine; and ③ bis(3-ethoxypropyl)dimethylaminopropylamine described in the present application. The corresponding foaming data are listed in Table 2.

[0094] Toluene diisocyanate (TDI-80) with a 2,4-isomer content of 80%, i.e., containing 80% of 2,4-TDI and 20% of 2,6-TDI.

[0095] Table 2, comparison of polyurethane foaming data obtained by different amine catalysts

[0096]

[0097]

[0098] From the foaming data in Table 2, it can be seen that the catalytic activity of tri(N,N-dimethylaminopropyl)amine is poorer than that of the commonly used amine catalyst A33 in commerce, while the bis(3-ethoxypropyl)dimethylaminopropylamine of the present application has more excellent catalytic activity due to the ethoxy structure of the end group. The foam prepared therefrom has high density and high tear strength, and can meet the increasingly high requirements for the performance of polyurethane foam materials.

[0099] Finally, it should be noted that the above enumeration is only several specific embodiments of the present application. Obviously, the present application is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or inferred by those of ordinary skill in the art from the disclosure of the present application should be considered within the scope of the present application.

Claims

1. Bis(3-ethoxypropyl)dimethylaminopropylamine, characterized in that... The structural formula is: 。 2. The method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 1, characterized in that... Includes the following steps: 1) Using acrylonitrile and bis(3-ethoxypropyl)amine as raw materials; firstly, bis(3-ethoxypropyl)amine is dissolved in methanol to obtain a methanol solution of bis(3-ethoxypropyl)amine, the temperature is raised to 40±10 ℃, and then acrylonitrile is added dropwise to the methanol solution of bis(3-ethoxypropyl)amine for reaction, the addition time is 3±0.5 h, and after the addition is completed, the reaction is continued at the temperature for 2±0.5 h; The molar ratio of bis(3-ethoxypropyl)amine to acrylonitrile was 1:(1±0.05); methanol accounted for 50%~100% of the mass of bis(3-ethoxypropyl)amine. 2) Transfer the reaction solution obtained in step 1) to a high-pressure reactor, add hydrogenation catalyst and inhibitor to the high-pressure reactor, replace the gas in the high-pressure reactor, and then introduce hydrogen into the high-pressure reactor. React for 3 to 6 hours under the conditions of hydrogen pressure of 2~4 MPa and reaction temperature of 50~100℃. The hydrogenation catalyst is 5-10% by mass of bis(3-ethoxypropyl)amine in step 1), and the inhibitor is 0.4-0.6% by mass of bis(3-ethoxypropyl)amine in step 1. The inhibitor is an inorganic base; The hydrogenation catalyst is any of the following: Raney Ni, Raney Co, Pd / C, Pt / C; 3) Add paraformaldehyde to the reaction liquid obtained in step 2) in the autoclave, replace the gas in the autoclave, then introduce hydrogen into the autoclave and react for 4 to 10 hours at a hydrogen pressure of 1.0 to 5.0 MPa and a reaction temperature of 30 ℃ to 150 ℃. Paraformaldehyde: Acrylonitrile in step 1) has a molar ratio of 2.0~3.0:1; The reaction product was post-processed to obtain bis(3-ethoxypropyl)dimethylaminopropylamine.

3. The method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 2, characterized in that: The inorganic base is any one of the following: sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium methoxide, or sodium ethoxide.

4. The method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 2 or 3, characterized in that: After the post-processing in step 3), a recyclable hydrogenation catalyst and methanol are also obtained.

5. The method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 4, characterized in that: The post-treatment in step 3) is as follows: vent the gas in the high-pressure reactor, then open the reactor and let it stand, filter, and obtain filtrate and filter cake respectively. The filtrate is a reaction solution containing bis(3-ethoxypropyl)dimethylaminopropylamine; the filter cake is a hydrogenation catalyst. The hydrogenation catalyst can be recovered after washing and reused. The filtrate was distilled under reduced pressure to obtain methanol fraction and bis(3-ethoxypropyl)dimethylaminopropylamine, respectively.

6. The method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 5, characterized in that: The recovered hydrogenation catalyst can be recycled for use in step 2). When recycling the hydrogenation catalyst, new catalyst needs to be added, and the amount of hydrogenation catalyst added is 5% to 10% of the set amount. The recovered methanol can be recycled for use in step 1). When recycling methanol, new methanol needs to be added, and the amount of methanol added is 5% to 10% of the set amount.

7. The use of bis(3-ethoxypropyl)dimethylaminopropylamine as described in claim 1, characterized in that: As a foaming catalyst for preparing polyurethane foam; the polyurethane foam formulation consists of the following components in parts by weight: 75-85 parts PTMEG-1000, 8-12 parts HFC-245fa, 8-12 parts ammonium polyphosphate, 2-4 parts water, 0.5-1.5 parts silicone oil 815H, 0.2-0.4 parts stannous octoate, 0.1-0.2 parts dibutyltin dilaurate, 0.3-0.7 parts amine catalyst, and 55-65 parts TDI-80, wherein the amine catalyst is bis(3-ethoxypropyl)dimethylaminopropylamine as described in claim 1.

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