Preparation method for foaming catalyst, and use of same in high-density high-strength polyurethane foam

Abstract

The present invention belongs to the field of organic synthesis, and particularly relates to a foaming catalyst bis(3-ethoxypropyl)dimethylaminopropylamine, a preparation method therefor, and the use of same in preparing a high-density high-strength polyurethane foam. The structural formula of bis(3-ethoxypropyl)dimethylaminopropylamine provided herein is as shown in (I). Also provided is the use of bis(3-ethoxypropyl)dimethylaminopropylamine: as a foaming catalyst for preparing the high-density high-strength polyurethane foam. A polyurethane foam prepared by means of applying bis(3-ethoxypropyl)dimethylaminopropylamine to a polyurethane foam formula has the advantages of high density and high strength.

Description

Preparation method of foaming catalyst and its application in high-density, high-strength polyurethane foam Technical Field

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

[0002] Polyurethane products have significant applications in foams, fibers, rubbers, elastomers, coatings, and adhesives, with polyurethane foam accounting for a significant portion of this market. In the production of polyurethane foam, foaming catalysts play a crucial role, primarily ensuring that the foaming system achieves optimal foaming and curing times, resulting in products with excellent mechanical and physical properties. For example, the commercially available amine catalyst A33 (a 33% triethylenediamine solution in dipropylene glycol) boasts high foaming activity and is used in a wide range of polyurethane-related applications. However, with the development of society, the performance requirements for polyurethane foams are becoming increasingly stringent, making it increasingly difficult for these catalysts to meet these requirements.

[0003] An existing foaming catalyst is tris(N,N-dimethylaminopropyl)amine, whose CAS number is 33329-35-0 and molecular formula is C 15 H 36 N4, with a molecular weight of 272.47, is prepared using 3-dimethylaminopropylamine and acrylonitrile as starting materials through Michael addition, catalytic hydrogenation, and hydromethylation. The polyurethane foam produced using this foaming catalyst has a formula of: PPG-2000, methane, flame retardant TPP, water, silicone oil 815H, stannous octoate, tris(N,N-dimethylaminopropyl)amine, and TDI-80. Summary of the Invention

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

[0005] In order to solve the above technical problems, the present invention provides a bis(3-ethoxypropyl)dimethylaminopropylamine, whose molecular formula is C 15 H 24 N2O2, molecular weight is 274.26, and its structural formula is:

[0006] Formula 1, the structural formula of bis(3-ethoxypropyl)dimethylaminopropylamine

[0007] The present invention also provides a method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine, comprising the following steps:

[0008] 1) Using acrylonitrile and bis(3-ethoxypropyl)amine as raw materials, first dissolve bis(3-ethoxypropyl)amine in methanol to obtain a methanol solution of bis(3-ethoxypropyl)amine, heat to 20-100°C (preferably 40±10°C), then dropwise add acrylonitrile to the methanol solution of bis(3-ethoxypropyl)amine to react for 2-5h (preferably 3±0.5h). After the dropwise addition is completed, continue to keep warm and react for 1-4h (preferably 2±0.5h);

[0009] The molar ratio of bis(3-ethoxypropyl)amine: acrylonitrile is 1:(1±0.05); the amount of methanol is 50% to 100% of the mass of bis(3-ethoxypropyl)amine;

[0010] Note: Methanol serves as both addition catalyst and solvent;

[0011] 2) The reaction solution obtained in step 1) (the reaction solution containing bis(3-ethoxypropyl)cyanoethylamine) is transferred to an autoclave, and a hydrogenation catalyst and an inhibitor are added to the autoclave. The gas in the autoclave is replaced (inert gas and hydrogen are used for gas replacement in sequence), and then hydrogen is introduced into the autoclave. The reaction is carried out at a hydrogen pressure of 1.0 to 5.0 MPa and a reaction temperature of 30° C. to 150° C. for 4 to 10 hours (preferably 2 to 4 MPa, 50 to 100° C., and 3 to 6 hours);

[0012] The hydrogenation catalyst is 1% to 20% (preferably 5 to 10%) of the mass of the bis(3-ethoxypropyl)amine in step 1), and the inhibitor is 0% to 10% (preferably 0.1% to 5%, more preferably 0.4 to 0.6%, more preferably 0.5%) of the mass of the bis(3-ethoxypropyl)amine in step 1);

[0013] 3) adding paraformaldehyde to the reaction solution (containing bis(3-ethoxypropyl)aminopropylamine) obtained in step 2) in the autoclave, replacing the gas in the autoclave (using inert gas and hydrogen for gas replacement in sequence), introducing hydrogen into the autoclave, and reacting for 4 to 10 hours at a hydrogen pressure of 1.0 to 5.0 MPa and a reaction temperature of 30° C. to 150° C.;

[0014] Paraformaldehyde: acrylonitrile from step 1) = 2.0-3.0:1 molar ratio;

[0015] The reaction product is post-treated to obtain bis(3-ethoxypropyl)dimethylaminopropylamine.

[0016] Description: In this step 3), bis(3-methoxypropyl)aminopropylamine and paraformaldehyde are used as raw materials, and catalytic hydrogenation and methylation are carried out in the presence of methanol solvent and a hydrogenation catalyst to prepare bis(3-ethoxypropyl)dimethylaminopropylamine.

[0017] As an improvement to the preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention, the step 2):

[0018] The inhibitor is an inorganic base;

[0019] The hydrogenation catalyst was any one of the following: Raney Ni, Raney Co, Pd / C (5 wt% Pd), Pt / C (5 wt% Pt).

[0020] As a further improvement of the preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention, the inorganic base is any one of the following: sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium methoxide, and sodium ethoxide.

[0021] As a further improvement to the preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention: after post-treatment in step 3), recyclable hydrogenation catalyst and methanol are also obtained.

[0022] As a further improvement to the preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention: the post-treatment of step 3) is as follows: venting the gas in the autoclave, then opening the autoclave and letting it stand, filtering to obtain a filtrate and a filter cake, respectively, wherein the filtrate is a reaction solution containing bis(3-ethoxypropyl)dimethylaminopropylamine; and the filter cake is a hydrogenation catalyst;

[0023] The hydrogenation catalyst can be recovered after washing and can be used for recycling;

[0024] The filtrate is distilled under reduced pressure to obtain a methanol fraction and bis(3-ethoxypropyl)dimethylaminopropylamine.

[0025] As a further improvement of the preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention:

[0026] The recovered hydrogenation catalyst can be recycled and used in step 2). Since the amount of catalyst is lost during the recovery process, it is necessary to replenish new hydrogenation catalyst when the hydrogenation catalyst is recycled. The replenishment amount is about 5% to 10% of the set amount of hydrogenation catalyst (original amount);

[0027] The recovered methanol can be recycled for step 1). Since the amount of methanol is lost during the recovery process, new methanol needs to be added when the methanol is recycled. The added amount is about 5% to 10% of the set amount.

[0028] The present invention also provides the use of bis(3-ethoxypropyl)dimethylaminopropylamine as a foaming catalyst for preparing polyurethane foam (high-density, high-strength polyurethane foam).

[0029] The present invention also provides a polyurethane foam (high-density, high-strength polyurethane foam): the polyurethane foam formula is composed of the following components in parts by weight:

[0030] 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 amine catalyst and 55-65 parts of TDI-80, wherein the amine catalyst is bis(3-ethoxypropyl)dimethylaminopropylamine.

[0031] The synthetic route of the present invention is as follows:

[0032] Formula 2, Synthesis Route of Bis(3-ethoxypropyl)dimethylaminopropylamine

[0033] The present invention aims to synthesize high-density, high-strength polyurethane foam. Existing A33-type catalysts are stereocatalysts, which may cause chain transfer during the catalytic foaming reaction, making it unfavorable for the synthesis of high-crosslinked-density polyurethane foam. However, considering that methoxy and ethoxy groups have good catalytic activity and good ether end group compatibility, compared with the structurally similar tris(N,N-dimethylaminopropyl)amine, the foaming reaction catalyzed by the foaming catalyst containing the structure described in the present invention, bis(3-ethoxypropyl)dimethylaminopropylamine, can produce a high-crosslinked-density and high-strength product. Therefore, starting from existing raw materials and based on the group characteristics of the raw materials, the present invention innovatively designs a compound, bis(3-ethoxypropyl)dimethylaminopropylamine, develops a corresponding process route, and proves through application that the compound, bis(3-ethoxypropyl)dimethylaminopropylamine, is a foaming catalyst that can be used to prepare high-density, high-strength polyurethane foam.

[0034] In summary, the present invention proposes using existing bis(3-ethoxypropyl)amine and acrylonitrile as raw materials to prepare bis(3-ethoxypropyl)dimethylaminopropylamine, a polyurethane foaming catalyst that can be used to synthesize high-density, high-strength polyurethane foam, through Michael addition, catalytic hydrogenation, and hydromethylation. Testing has shown that the bis(3-ethoxypropyl)dimethylaminopropylamine described in the present invention is a good polyurethane foaming catalyst. The resulting polyurethane foam exhibits the advantages of high density and high strength. The synthesis method has not yet been reported in the literature.

[0035] The raw material used in the present invention is bis(3-ethoxypropyl)amine, the molecular formula of which is C10 H 23 NO2, CAS No. 19235-38-2, its synthesis method can refer to the applicant's existing patent CN117209385A, for example.

[0036] The present invention has the following technical advantages:

[0037] 1. Step 2) By selecting a suitable inhibitor, only a small amount of inhibitor is needed to produce primary amines with high selectivity, effectively preventing the disproportionation side reaction; and the hydrogenation reaction liquid can be continuously subjected to the next N-methylation reaction, reducing the number of operation steps;

[0038] 2. Both methanol and hydrogenation catalyst can be recycled to reduce production costs;

[0039] 3. The bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention is used in polyurethane foam formulations, and the obtained polyurethane foam has the advantages of high density and high strength.

[0040] In summary, the present invention 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 THE DRAWINGS

[0041] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0042] Figure 1 is a diagram of bis(3-ethoxypropyl)dimethylaminopropylamine 1 HNMR spectrum. DETAILED DESCRIPTION

[0043] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:

[0044] Steps 1) to 3) of the present invention are all carried out under conventional stirring conditions.

[0045] Example 1: A method for preparing bis(3-ethoxypropyl)dimethylaminopropylamine, comprising the following steps:

[0046] 1) 378.3 g (2.0 mol) of bis(3-ethoxypropyl)amine was added to a reactor, and 189.2 g of methanol was added thereto. After stirring and mixing, the temperature was raised to a reaction temperature of 40°C. 106.1 g (2.0 mol) of acrylonitrile was added dropwise to the reactor within 3 h to react. After the addition of acrylonitrile was completed, stirring was maintained and the reaction was kept warm for 2 h to obtain a reaction solution containing bis(3-ethoxypropyl)cyanoethylamine.

[0047] 2) The entire reaction solution obtained in step 1) was transferred to an autoclave, and 18.9 g of Raney Ni catalyst (as a hydrogenation catalyst) and 1.9 g of potassium hydroxide (as an inhibitor) were added. The autoclave was then closed, and the atmosphere was replaced with nitrogen three times and hydrogen three times. After replacement, the autoclave was pressurized with hydrogen to an initial pressure of 1.5 MPa. The temperature was raised to the reaction temperature of 50°C, and hydrogen was added to a pressure of 2.0 MPa. The pressure was then maintained constant and the reaction was carried out at 50°C for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and the atmosphere was vented to obtain a reaction solution containing bis(3-ethoxypropyl)aminopropylamine.

[0048] 3) 120 g (4.0 mol) of paraformaldehyde was added to the reaction solution containing bis(3-ethoxypropyl)aminopropylamine in the reactor obtained in step 2), and the reactor was then closed. The gas in the reactor was replaced with nitrogen three times and with hydrogen three times. After the replacement was completed, the reactor was pressurized with hydrogen to an initial pressure of 1.5 MPa. The temperature was slowly raised to a reaction temperature of 80° C., and hydrogen was added to a pressure of 2.0 MPa. The pressure was then maintained constant and the reaction was carried out at 80° C. for 5 h to obtain a reaction solution containing bis(3-ethoxypropyl)dimethylaminopropylamine.

[0049] After the reaction, the temperature was lowered and the gas in the autoclave was vented. The autoclave was opened and allowed to stand for 1 hour, and then filtered to obtain a filtrate and a filter cake, respectively. The filtrate was a reaction liquid containing bis(3-ethoxypropyl)dimethylaminopropylamine; and the filter cake was a Raney Ni catalyst.

[0050] The filter cake is washed with methanol three times and then recovered, and can be used as a recycled catalyst;

[0051] The filtrate was distilled, and the methanol fraction at 65°C was collected under normal pressure. The fraction at 140°C was collected under reduced pressure at 300 Pa to obtain bis(3-ethoxypropyl)dimethylaminopropylamine.

[0052] 465 g of bis(3-ethoxypropyl)dimethylaminopropylamine with a purity of 99.5% was obtained as a product, and the final product yield was 84.8%. 180 g of methanol and 18 g of Raney Ni catalyst were recovered.

[0053] Product yield = the amount of bis(3-ethoxypropyl)dimethylaminopropylamine actually obtained by distillation / the amount of bis(3-ethoxypropyl)dimethylaminopropylamine theoretically obtained.

[0054] Bis(3-ethoxypropyl)dimethylaminopropylamine, whose molecular formula is C 15 H 24 N2O2, molecular weight is 274.26, structural formula:

[0055] 1 The H NMR spectrum is shown in Figure 1.

[0056] Example 2-1: Compared with Example 1, the following changes are made:

[0057] The catalyst in step 2) was changed from Raney Ni to Pd / C (5 wt % Pd), and the weight remained unchanged at 18.9 g; the rest was the same as in Example 1.

[0058] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product was 50.9%.

[0059] Example 2-2: Compared with Example 1, the following changes are made:

[0060] The catalyst in step 2) was changed from Raney Ni to Pt / C (5 wt % Pt), and the weight remained unchanged at 18.9 g; the rest was the same as in Example 1.

[0061] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product is 46.7%.

[0062] Example 2-3: Compared with Example 1, the following changes are made:

[0063] The catalyst in step 2) was changed from Raney Ni to Raney Co, and the weight remained unchanged at 18.9 g; the rest was the same as in Example 1.

[0064] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product is 65.3%.

[0065] Example 3: Compared with Example 1, the following changes are made:

[0066] The amount of catalyst in step 2) was changed from 18.9 g to 37.8 g, and the rest was the same as in Example 1.

[0067] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product is 82.2%.

[0068] Example 4: With respect to Example 1, the following changes are made:

[0069] The reaction pressure of step 2) was changed from 2.0 MPa to 4.0 MPa, and the reaction time was changed to 5 h; and the reaction pressure of step 3) was changed from 2.0 MPa to 4.0 MPa, and the reaction time was changed to 4 h; the rest was the same as Example 1.

[0070] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product is 85.5%.

[0071] Example 5: With respect to Example 1, the following changes are made:

[0072] The reaction temperature of step 2) was changed from 50°C to 100°C, and the reaction time was changed to 3 h; the reaction temperature of step 3) was changed from 80°C to 120°C, and the reaction time was changed to 2.5 h; the rest was the same as Example 1.

[0073] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product is 79.4%.

[0074] Example 6: The amount of methanol in Example 1 was changed from 189.2 g to 378.3 g, and the rest was the same as in Example 1.

[0075] The yield of the obtained bis(3-ethoxypropyl)dimethylaminopropylamine product is 85.2%.

[0076] Example 7, cyclic application:

[0077] Compared to Example 1, the "18.9 g Raney Ni catalyst" in step 2) was replaced with "18 g of Raney Ni catalyst recovered in step 3) of Example 1 and supplemented with 0.9 g of fresh Raney Ni catalyst." The rest of the process was the same as in Example 1. This represents the recycling process corresponding to the first recovery.

[0078] Similarly, the Raney Ni catalyst recovered in the first recovery was supplemented with fresh Raney Ni catalyst until the total weight was 18.9 g, which was used as the catalyst. This was the corresponding cycle for the second recovery.

[0079] The corresponding relationship between the number of times the catalyst was recycled and the results obtained is shown in Table 1 below.

[0080] Table 1. Experimental results of different times of hydrogenation catalyst recycling

[0081] Comparative Example 1-1: With respect to Example 1, the following changes were made:

[0082] The amount of potassium hydroxide as an inhibitor in step 2) was changed from 0.5% to 0; the rest was the same as in Example 1.

[0083] The yield of bis(3-ethoxypropyl)dimethylaminopropylamine obtained in step 3) is 75.4%.

[0084] Comparative Example 1-2: With respect to Example 1, the following changes were made:

[0085] The amount of potassium hydroxide as the inhibitor in step 2) was changed from 0.5% to 5%; the rest was the same as in Example 1.

[0086] The yield of bis(3-ethoxypropyl)dimethylaminopropylamine obtained in step 3) is 62.8%.

[0087] Experiment 2: Using bis(3-ethoxypropyl)dimethylaminopropylamine as an amine catalyst to prepare high-density, high-strength polyurethane foam, as follows:

[0088] 80 parts of PTMEG-1000 (polytetramethylene 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 were added to the mixing barrel in sequence according to the mass parts. After mixing and stirring for 10 seconds with a stirrer at a speed of 3000r / min, the mixture was allowed to stand for 1 minute. Then, 60 parts of toluene diisocyanate (TDI-80) with a 2,4-body content of 80% were poured into the mold. The temperature was controlled at room temperature, the timing was started, and after rapid stirring for 3 seconds, the mixture was poured into a foaming box for foaming. After ripening, it was cut into the required size and performance tested.

[0089] Under the same experimental conditions, the foaming effects of three amine catalysts were compared: ① A33 (33% triethylenediamine solution, solvent: dipropylene glycol), a commonly used commercial amine catalyst; ② tris(N,N-dimethylaminopropyl)amine; and ③ bis(3-ethoxypropyl)dimethylaminopropylamine described in the present invention. The corresponding foaming data are listed in Table 2.

[0090] Toluene diisocyanate (TDI-80) with a 2,4-isomer content of 80%, that is, containing 80% 2,4-TDI and 20% 2,6-TDI.

[0091] Table 2. Comparison of polyurethane foaming data obtained with different amine catalysts

[0092] From the foaming data in Table 2, it can be concluded that tris(N,N-dimethylaminopropyl)amine has poor catalytic activity compared to the commonly used commercial amine catalyst A33, while the bis(3-ethoxypropyl)dimethylaminopropylamine of the present invention has more excellent catalytic activity due to the ethoxy structure of the terminal group. The foam prepared therefrom has high density and high tear strength, which can meet the increasingly high performance requirements of polyurethane foam materials today.

[0093] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples and is subject to numerous variations. All variations that can be directly derived or conceived by a person of ordinary skill in the art from the disclosure of the present invention are considered to be within the scope of protection of the present invention.

Claims

1. Bis(3-ethoxypropyl) dimethylaminopropylamine, characterized in that The structural formula is:

2. Preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine, characterized in that It includes the following steps: 1), Using acrylonitrile and bis(3-ethoxypropyl)amine as raw materials; first dissolve bis(3-ethoxypropyl)amine in methanol to obtain a methanol solution of bis(3-ethoxypropyl)amine, heat it up to 20 - 100 °C, and then dropwise add acrylonitrile to the methanol solution of bis(3-ethoxypropyl)amine for reaction. The dropping time is 2 - 5 h. After the dropping is completed, continue to keep warm and react for 1 - 4 h; The molar ratio of bis(3-ethoxypropyl)amine to acrylonitrile is 1:(1 ± 0.05); the methanol is 50% - 100% of the mass of bis(3-ethoxypropyl)amine; 2), Transfer the reaction solution obtained in step 1) to an autoclave, then add a hydrogenation catalyst and an inhibitor to the autoclave. After gas replacement in the autoclave, then introduce hydrogen gas into the autoclave, and react under the conditions of a hydrogen pressure of 1.0 - 5.0 MPa and a reaction temperature of 30 °C - 150 °C for 4 - 10 h; The hydrogenation catalyst is 1% - 20% of the mass of bis(3-ethoxypropyl)amine in step 1), and the inhibitor is 0% - 10% of the mass of bis(3-ethoxypropyl)amine in step 1); 3), Add paraformaldehyde to the reaction solution located in the autoclave obtained in step 2). After gas replacement in the autoclave, introduce hydrogen gas into the autoclave, and react under the conditions of a hydrogen pressure of 1.0 - 5.0 MPa and a reaction temperature of 30 °C - 150 °C for 4 - 10 hours; The molar ratio of paraformaldehyde to acrylonitrile in step 1) is 2.0 - 3.0:1; Perform post-treatment on the reaction product to obtain bis(3-ethoxypropyl)dimethylaminopropylamine.

3. The preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 2, characterized in that The said step 2): The inhibitor is an inorganic base; The hydrogenation catalyst is any one of the following: Raney Ni, Raney Co, Pd / C, Pt / C.

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

5. The preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine according to any one of claims 2 to 4, characterized in that: After the post-treatment of step 3), a recoverable hydrogenation catalyst and methanol are also obtained.

6. The preparation method of bis(3-ethoxypropyl)dimethylaminopropylamine according to claim 5, characterized in that: The post-treatment of step 3) is: vent the gas in the autoclave, then open the autoclave and let it stand still, filter, and obtain a filtrate and a filter cake respectively. The filtrate is a reaction solution containing bis(3-ethoxypropyl)dimethylaminopropylamine; the filter cake is the hydrogenation catalyst; [[ID= ​ ​ ​ ​ 8. Use of bis(3-ethoxypropyl)dimethylaminopropylamine, characterized in that: ​ 9. A polyurethane foam, characterized in that ​ 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 amine catalyst, and 55 - 65 parts of TDI - 80, wherein the amine catalyst is bis(3 - ethoxypropyl)dimethylaminopropylamine.

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