A method for synthesizing aza-cyclic modified hydroxyalkyl diethanolamine borate linkers

Abstract

The application discloses a synthesis method of aza-cyclic modified hydroxyalkyl diethanolamine borate linking agent, which comprises the following steps: (1) adding hydroxyalkyl diethanolamine and boric acid into a three-neck flask provided with a stirrer, a thermometer and a vacuum distillation device, and stirring and heating to react until no water is generated; (2) adding an aza-cyclic compound into the reaction system obtained in the step (1), increasing the reaction temperature, and removing water generated in the reaction by vacuum distillation when no water vapor is generated, so as to obtain a target product. The borate linking agent obtained by the synthesis method has good hydrolysis resistance, and when the borate linking agent is used in a hydroxyl-terminated solid propellant, the mechanical properties of the hydroxyl-terminated solid propellant can be effectively improved.

Description

Technical Field

[0001] This invention relates to a method for synthesizing a nitrogen-modified hydroxyalkyl diethanolamine borate ester bonding agent. Background Technology

[0002] Hydroxybutadiene (HbA1c) solid propellants are widely used due to their low cost, high energy performance, and excellent mechanical properties. With the development of advanced solid propellants, developing HbA1c solid propellants with even higher energy and better combustion performance has become an important trend for future development.

[0003] For hydroxyl-butadiene solid propellants containing small amounts of high-energy nitramine compounds (such as cyclotrimethylenetrinitramine, or RDX), borate esters are generally used as bonding agents. Borate ester bonding agents can chemically bond with other components in the propellant, forming a more stable structure, thereby improving the propellant's combustion efficiency and stability. Furthermore, borate ester bonding agents also possess excellent antioxidant and corrosion resistance, extending the propellant's service life. However, most existing borate ester bonding agents suffer from poor hydrolytic stability and unstable performance, making it difficult to meet the needs of practical applications. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for synthesizing a nitrogen-modified hydroxyalkyl diethanolamine borate ester bonding agent. The bonding agent obtained by this method has good hydrolytic stability, and when used in hydroxyl-butyl solid propellants, it can effectively improve the mechanical properties of hydroxyl-butyl solid propellants.

[0005] Technical solution: The synthesis method of the nitrogen-modified hydroxyalkyl diethanolamine borate ester bonding agent of the present invention includes the following steps:

[0006] (1) Add hydroxyalkyl diethanolamine and boric acid to a three-necked flask equipped with a stirrer, thermometer and vacuum distillation apparatus, stir and heat to react until no water is produced;

[0007] (2) Add a nitrogen heterocyclic compound to the reaction system obtained in step (1), increase the reaction temperature, and when no water is produced, remove the water generated by the reaction by vacuum distillation to obtain the target product.

[0008] In step (1), the chemical structural formula of the hydroxyalkyl diethanolamine is: In the formula, the number of CH2 atoms in the alkyl chain is 2≤n≤18; the molar ratio of the hydroxyalkyl diethanolamine to boric acid is 1:3~3:1. The reaction temperature is 120~160°C, and the stirring speed is 170~270 r / min.

[0009] In step (2), the nitrogen heterocyclic compound is one of a hydroxyalkyl-substituted hydantoin derivative, a hydroxyalkyl-substituted triazine derivative, or a hydroxyalkyl-substituted cyanuric acid derivative.

[0010] When the nitrogen heterocyclic compound is a hydroxyalkyl-substituted hydantoin derivative, the nitrogen heterocyclic compound is 1,3-dihydroxymethyl-5,5-dimethylhydantoin (CAS: 6640-58-0) and 1,3-dihydroxyethyl-5,5-diethylhydantoin (CAS: 26850-24-8); when the nitrogen heterocyclic compound is a hydroxyalkyl-substituted triazine derivative, the nitrogen heterocyclic compound is tris(hydroxymethyl)hexahydro-1,3,5-triazine (CAS: 79876-19-0) and tris(hydroxyethyl)hexahydro-1,3,5-triazine (CAS: 4719-04-4); when the nitrogen heterocyclic compound is a hydroxyalkyl-substituted cyanuric acid derivative, the nitrogen heterocyclic compound is 1,3,5-tris(hydroxymethyl)cyanuric acid (CAS: 10471-40-6) and 1,3,5-tris(2-hydroxyethyl)cyanuric acid (CAS: 839-90-7).

[0011] In step (2), the molar ratio of the nitrogen heterocyclic compound to hydroxyalkyl diethanolamine is 1:3 to 3:1.

[0012] In step (2), the reaction temperature is increased to 160~200°C and the stirring speed is 150~250r / min.

[0013] The synthesis method of this invention uses hydroxyalkyl diethanolamine as the reaction basis, in which part of it reacts with boric acid to form a stable cyclic borate ester structure, and the other part reacts with a nitrogen heterocycle containing a terminal hydroxyl group, thereby achieving the modification of the borate ester bonding agent by the nitrogen heterocycle, so that the obtained borate ester bonding agent has good hydrolytic stability.

[0014] The bonding agent of the present invention is applicable to solid propellant systems containing ammonium perchlorate (AP), RDX (RDX), and hydroxyl-terminated polybutadiene (HTPB) as a binder. The application of the above bonding agent in the preparation of hydroxyl-terminated solid propellants, wherein the hydroxyl-terminated solid propellant comprises the following components by mass percentage: binder (HTPB) 7%~9%, aluminum powder 16%~18%, ammonium perchlorate 60%~63%, RDX (cyclotrimethylenetrinitramine) 8%~10%, functional additives (fuel, etc.) 3.6%~4.5%, and bonding agent 0.3%~0.5%.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0016] (1) The borate ester bonding agent synthesized in this invention contains an eight-membered ring structure, which can significantly improve its hydrolytic stability compared to a single branched chain; at the same time, the introduced nitrogen heterocycle can increase its steric hindrance, further enhancing its hydrolytic stability; in addition, the coiled alkyl chain can also coat and protect the borate group, thereby isolating water molecules from contact with the borate group, further improving the hydrolytic stability of the borate ester bonding agent.

[0017] (2) The hydroxyl groups contained in the borate ester bonding agent of the present invention can react with the isocyanate groups in the adhesive and thus enter the crosslinking network of the adhesive. At the same time, the nitrogen atoms in the bonding agent can interact strongly with the nitro groups of the nitramine compound (RDX), thereby improving the interfacial adhesion performance between RDX and the adhesive HTPB, and thus enhancing the mechanical properties of the solid propellant.

[0018] (3) The borate ester bonding agent used in this invention has a long carbon chain structure and a strong interaction force with the surface of the solid oxidant. This structural characteristic can inhibit the bonding agent from migrating excessively into the HTPB crosslinked network polymer during the crosslinking and curing process, thereby enabling it to remain in the interface region more effectively to play a bonding role, and ultimately significantly improve the bonding effect. Attached Figure Description

[0019] Figure 1 The mass spectrum of the target product obtained in Example 1 is shown below.

[0020] Figure 2 The mass spectrum of the target product obtained in Example 2;

[0021] Figure 3 This is the mass spectrum of the target product obtained in Example 3. Detailed Implementation

[0022] Example 1

[0023] The method for synthesizing the nitrogen-modified hydroxyalkyl diethanolamine borate ester bonding agent of the present invention is as follows:

[0024] At room temperature, accurately weigh 47.6 g of N,N-bis(2-hydroxyethyl)-8-hydroxyoctylamine (this substance is based on the literature Newexamples of triangular terbium(III) and holmium(III) and hexagonaldysprosium(III) single molecule toroics, Dalton Trans., 2019, 48, ). The reaction mixture (prepared by the method reported in 15657) and 15.3 g of boric acid were added to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus. The mixture was heated to 160°C. When the top temperature reached 98°C, water began to evaporate. When no more water evaporated, the top temperature was lowered to 96°C, and then 47.6 g of tris(hydroxymethyl)hexahydro-1,3,5-triazine was added. After the addition was complete, the temperature was raised to 180°C. When no more water evaporated, the mixture was vacuum distilled for 0.5 h to 1 h to remove the remaining water, and the reaction was terminated. The mixture was then cooled to 120°C to obtain the target product.

[0025] The target product was detected, and the mass spectrometry data of the product were as follows: Figure 1 As shown, the mass spectrometry data reveals that the main fragment ion signal peak observed is m / z=418.4, which corresponds to the hydroxyoctyl diethanolamine borate ester bonder modified with a hydroxyalkyl-substituted triazine derivative.

[0026] The reaction equation for the above reaction is:

[0027]

[0028] The borate ester bonding agent prepared in Example 1 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which comprises the following components by mass percentage: 8% binder (HTPB), 18% aluminum powder, 62% ammonium perchlorate, 8% RDX (cyclotrimethylenetrinitramine), 3.7% functional additives, and 0.3% bonding agent.

[0029] The above-mentioned hydroxyl-butyl tetracomponent solid propellant was tested, and the maximum tensile strength was 0.98 MPa, the maximum elongation was 60.2%, and the maximum elongation at break was 67.4%.

[0030] Example 2

[0031] The method for synthesizing the nitrogen-modified hydroxyalkyl diethanolamine borate ester bonding agent of the present invention is as follows:

[0032] At room temperature, accurately weigh 35.4 g of N,N-bis(2-hydroxyethyl)-4-hydroxybutylamine (CAS: 15026-69-4) and 21.5 g of boric acid, and add the above reactants to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus; heat to 140°C, and when the top temperature reaches 98°C, water begins to evaporate; when no more water evaporates, the top temperature drops to 96°C, and then add 42.9 g of tris(hydroxymethyl)hexahydro-1,3,5-triazine. After the addition is complete, raise the temperature to 170°C, and when no more water evaporates, remove the remaining water by vacuum distillation for 0.5 h to 1 h, ending the reaction. Cool to 120°C to obtain the target product.

[0033] The target product was detected, and the mass spectrometry data of the product were as follows: Figure 2 As shown, the mass spectrometry data reveals that the main fragment ion signal peak observed is m / z=362.3, corresponding to the triazine derivative-modified hydroxybutyryl diethanolamine borate ester bonding agent.

[0034] The reaction equation for the above reaction is:

[0035]

[0036] The borate ester bonding agent prepared in Example 2 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which comprises the following components by mass percentage: 7% binder (HTPB), 16% aluminum powder, 63% ammonium perchlorate, 10% RDX (cyclotrimethylenetrinitramine), 3.6% functional additives, and 0.4% bonding agent.

[0037] The above-mentioned hydroxyl-butyl tetracomponent solid propellant was tested, and the maximum tensile strength was 0.91 MPa, the maximum elongation was 53.5%, and the maximum elongation at break was 61.2%.

[0038] Example 3

[0039] The method for synthesizing the nitrogen-modified hydroxyalkyl diethanolamine borate ester bonding agent of the present invention is as follows:

[0040] At room temperature, accurately weigh 35.8 g of triethanolamine (CAS: 102-71-6) and 13.3 g of boric acid, and add the reactants to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus. Heat to 140°C; when the top temperature reaches 98°C, water begins to evaporate. When no more water evaporates, lower the top temperature to 96°C, and then add 59.3 g of 1,3,5-tris(2-hydroxyethyl)cyanuric acid. After the addition is complete, raise the temperature to 190°C. When no more water evaporates, remove the remaining water by vacuum distillation for 0.5-1 hour, ending the reaction. Cool to 105°C to obtain the target product. Analyze the target product; the mass spectrometry data are as follows: Figure 3 As shown.

[0041] pass Figure 3 Data showed that the observed fragment ion signal peak (m / z = 419.3) could be attributed to a hydroxyethyl diethanolamine borate ester binder modified by a hydroxyalkyl-substituted cyanuric acid derivative formed by one molecule of boric acid, one molecule of 1,3,5-tris(2-hydroxyethyl)cyanuric acid, and one molecule of triethanolamine. A significant byproduct signal peak (m / z = 306.3) was also detected, corresponding to the borate ester formed by the reaction of boric acid with two molecules of triethanolamine. This indicates that in the reaction system, due to the short alkyl chain and low steric hindrance of triethanolamine, its hydroxyl groups exhibit high reactivity, leading to the formation of byproducts and a decrease in the purity of the target product, which is approximately 34%.

[0042] The reaction equation for the above reaction is:

[0043]

[0044] The borate ester bonding agent prepared in Example 3 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which comprises the following components by mass percentage: 9% binder (HTPB), 16% aluminum powder, 60% ammonium perchlorate, 10% RDX (cyclotrimethylenetrinitramine), 4.5% functional additives, and 0.5% bonding agent.

[0045] The above-mentioned hydroxyl-butadiene quaternary solid propellant was tested, and the maximum tensile strength was 0.87 MPa, the maximum elongation was 54.3%, and the maximum elongation at break was 67.8%.

[0046] Comparative Example 1 – Compared to Example 1, Comparative Example 1 uses N-octyldiethanolamine to prepare a nitrogen-modified borate ester bonding agent. The specific preparation process is as follows:

[0047] At room temperature, 48.9 g of N-octyldiethanolamine and 15.3 g of boric acid were accurately weighed and added to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus. The mixture was heated to 160°C. When the top temperature reached 98°C, water began to evaporate. When no more water evaporated, the top temperature was lowered to 96°C. Then, 47.6 g of tris(hydroxymethyl)hexahydro-1,3,5-triazine was added. After the addition was complete, the temperature was raised to 180°C. When no more water evaporated, the mixture was vacuum distilled for 0.5-1 hour to remove the remaining water, thus ending the reaction. The mixture was then cooled to 120°C to obtain the target product. The reaction equation is as follows:

[0048]

[0049] The borate ester bonding agent prepared in Comparative Example 1 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which included the following components by mass percentage: 8% binder (HTPB), 18% aluminum powder, 62% ammonium perchlorate, 8% RDX (cyclotrimethylenetrinitramine), 3.7% functional additives, and 0.3% bonding agent.

[0050] The above-mentioned hydroxyl-butadiene quaternary solid propellant was tested, and the maximum tensile strength was 0.61 MPa, the maximum elongation was 50.2%, and the maximum elongation at break was 58.3%.

[0051] Comparative Example 2 – Compared to Example 1, Comparative Example 2 uses N,N-bis(2-hydroxyethyl)-19-hydroxynonadecanine to prepare a nitrogen-modified borate ester bonding agent. The specific preparation process is as follows:

[0052] At room temperature, accurately weigh 80.2 g of N,N-bis(2-hydroxyethyl)-19-hydroxynonadecanamine (this substance is based on the literature Newexamples of triangular terbium(III) and holmium(III) and hexagonaldysprosium(III) single molecule toroics, Dalton Trans., 2019, 48). The reaction mixture (prepared by the method reported in 15657) and 15.3 g of boric acid were added to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus. The mixture was heated to 160°C. When the top temperature reached 98°C, water began to evaporate. When no more water evaporated, the top temperature was lowered to 96°C, and then 47.6 g of tris(hydroxymethyl)hexahydro-1,3,5-triazine was added. After the addition was complete, the temperature was raised to 180°C. When no more water evaporated, the mixture was vacuum distilled for 0.5-1 hour to remove the remaining water, ending the reaction. The mixture was then cooled to 120°C to obtain the target product. The reaction equation is as follows:

[0053]

[0054] The borate ester bonding agent prepared in Comparative Example 2 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which included the following components by mass percentage: 8% binder (HTPB), 18% aluminum powder, 62% ammonium perchlorate, 8% RDX (cyclotrimethylenetrinitramine), 3.7% functional additives (fuel, etc.) and 0.3% bonding agent.

[0055] The above-mentioned hydroxyl-butadiene quaternary solid propellant was tested, and the maximum tensile strength was 0.64 MPa, the maximum elongation was 52.1%, and the maximum elongation at break was 58.3%.

[0056] Comparative Example 3 – Compared to Example 1, Comparative Example 3 uses 3-hydroxypyrrolidine to prepare a nitrogen-modified borate ester bonding agent. The specific preparation process is as follows:

[0057] At room temperature, 47.6 g of N,N-bis(2-hydroxyethyl)-8-hydroxyoctylamine and 15.3 g of boric acid were accurately weighed and added to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus. The mixture was heated to 160°C. When the top temperature reached 98°C, water began to evaporate. When no more water evaporated, the top temperature was lowered to 96°C, and then 17.4 g of 3-hydroxypyrrolidine was added. After the addition was complete, the temperature was raised to 180°C. When no more water evaporated, the mixture was vacuum distilled for 0.5-1 hour to remove the remaining water, thus ending the reaction. The mixture was then cooled to 120°C to obtain the target product. The reaction equation is as follows:

[0058]

[0059] The borate ester bonding agent prepared in Comparative Example 3 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which included the following components by mass percentage: 8% binder (HTPB), 18% aluminum powder, 62% ammonium perchlorate, 8% RDX (cyclotrimethylenetrinitramine), 3.7% functional additives, and 0.3% bonding agent.

[0060] The above-mentioned hydroxyl-butadiene quaternary solid propellant was tested, and the maximum tensile strength was 0.72 MPa, the maximum elongation was 63.6%, and the maximum elongation at break was 67.5%.

[0061] Comparative Example 4 – Compared to Example 1, Comparative Example 4 did not undergo the second step of nitrogen heterocyclic modification. The specific preparation process was as follows:

[0062] At room temperature, accurately weigh 47.6 g of N,N-bis(2-hydroxyethyl)-8-hydroxyoctylamine and 15.3 g of boric acid, and add the reactants to a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and vacuum distillation apparatus. Heat to 160°C; when the top temperature reaches 98°C, water begins to evaporate. When no more water evaporates, remove the remaining water by vacuum distillation for 0.5-1 hour, thus ending the reaction and obtaining the target product. The reaction equation is as follows:

[0063]

[0064] The borate ester bonding agent prepared in Comparative Example 4 was applied to a high-solids-content hydroxyl tetracomponent solid propellant, which included the following components by mass percentage: 8% binder (HTPB), 18% aluminum powder, 62% ammonium perchlorate, 8% RDX (cyclotrimethylenetrinitramine), 3.7% functional additives, and 0.3% bonding agent.

[0065] The above-mentioned butyl hydroxyl quaternary solid propellant was tested, and the maximum tensile strength was 0.55 MPa, the maximum elongation was 51.2%, and the maximum elongation at break was 59.5%.

[0066] The borate ester bonding agents prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to hydrolytic stability tests. For nitrogen-containing borate esters, considering their inherent alkalinity significantly affects the endpoint of the acid-base neutralization method, the saturated steam method was used to determine hydrolytic resistance. Experiments showed that the hydrolysis times of the borate ester bonding agents obtained in Examples 1-3 were all greater than 360 hours, while those in Comparative Examples 1-4 were 182 hours, 352 hours, 16 hours, and 10 hours, respectively. This indicates that the hydrolytic stability of the borate ester bonding agents obtained in Examples 1-3 is far superior to that of the products in Comparative Examples 1-4.

Claims

1. A method for synthesizing a nitrogen-heterocyclic modified hydroxyalkyl diethanolamine borate ester bonding agent, characterized in that, Includes the following steps: (1) Add hydroxyalkyl diethanolamine and boric acid to a three-necked flask equipped with a stirrer, thermometer and vacuum distillation apparatus, stir and heat to react until no water is produced; (2) Add a nitrogen heterocyclic compound to the reaction system obtained in step (1), increase the reaction temperature, and wait until no water is produced before removing the water generated by vacuum distillation to obtain the target product.

2. The synthesis method according to claim 1, characterized in that: In step (1), the chemical structural formula of the hydroxyalkyl diethanolamine is: In the formula, the number of CH2 atoms in the alkyl chain is 2≤n≤18.

3. The synthesis method according to claim 1, characterized in that: In step (1), the molar ratio of the added hydroxyalkyl diethanolamine and boric acid is 1:3 to 3:

1.

4. The synthesis method according to claim 1, characterized in that: In step (1), the reaction temperature is 120~160°C.

5. The synthesis method according to claim 1, characterized in that: In step (1), the stirring speed during the reaction process is 170~270 r / min.

6. The synthesis method according to claim 1, characterized in that: In step (2), the nitrogen heterocyclic compound is one of a hydroxyalkyl-substituted hydantoin derivative, a hydroxyalkyl-substituted triazine derivative, or a hydroxyalkyl-substituted cyanuric acid derivative.

7. The synthesis method according to claim 6, characterized in that: When the nitrogen heterocyclic compound is a hydroxyalkyl-substituted hydantoin derivative, the nitrogen heterocyclic compound is 1,3-dihydroxymethyl-5,5-dimethylhydantoin and 1,3-dihydroxyethyl-5,5-diethylhydantoin; when the nitrogen heterocyclic compound is a hydroxyalkyl-substituted triazine derivative, the nitrogen heterocyclic compound is tris(hydroxymethyl)hexahydro-1,3,5-triazine and tris(hydroxyethyl)hexahydro-1,3,5-triazine; when the nitrogen heterocyclic compound is a hydroxyalkyl-substituted cyanuric acid derivative, the nitrogen heterocyclic compound is 1,3,5-tris(hydroxymethyl)cyanuric acid and 1,3,5-tris(2-hydroxyethyl)cyanuric acid.

8. The synthesis method according to claim 1, characterized in that: In step (2), the molar ratio of the nitrogen heterocyclic compound to hydroxyalkyl diethanolamine is 1:3 to 3:

1.

9. The synthesis method according to claim 1, characterized in that: In step (2), the reaction temperature is increased to 160~200°C.

10. The synthesis method according to claim 1, characterized in that: In step (2), the stirring speed during the reaction process is 150~250 r / min.

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