A high-temperature-resistant resin with a double-curing system for solid rocket engines and a preparation method thereof

Abstract

The application relates to the technical field of solid rocket engines, and discloses a double-curing-system high-temperature-resistant resin for a solid rocket engine and a preparation method thereof. The preparation method comprises the following steps: modifying a multifunctional epoxy resin by grafting an azido group to obtain an azido-modified multifunctional epoxy resin; modifying a multifunctional aromatic amine by an alkyne group to obtain an alkyne-modified aromatic amine epoxy curing agent; mixing the azido-modified multifunctional epoxy resin and the alkyne-modified aromatic amine epoxy curing agent to obtain a mixed resin, adding an active diluent, a catalyst and an accelerator, and using a curing procedure to obtain a double-curing-system high-temperature-resistant resin; the preparation method significantly improves the heat resistance of the wet-wound epoxy resin, can be used for wet-wound forming of a solid rocket engine shell, and is widely applied to application fields, such as a solid rocket engine composite material nozzle shell, which have extremely strict requirements on weight, heat resistance and processability.

Description

Technical Field

[0001] This invention relates to the field of solid rocket motor technology, and in particular to a high-temperature resistant resin with a dual-curing system for solid rocket motors and its preparation method. Background Technology

[0002] To improve engine efficiency and reduce negative mass, large solid rocket motors are generally manufactured using a wet winding process, typically employing epoxy resin systems. However, conventional epoxy resin systems have low heat resistance, and their performance rapidly degrades under aerodynamic heat during rocket flight, affecting the overall safety of the engine. The application of curing systems combining multifunctional epoxy resins with aromatic polyamines is an effective means to improve the heat resistance of wet-wound epoxy resins. Due to the presence of a large number of high-stiffness benzene rings and a high degree of crosslinking, these systems exhibit high heat resistance. However, due to the inherent heat resistance limitations of epoxy resin systems, currently applicable epoxy resin systems suitable for wet winding have a glass transition temperature not exceeding 220℃, which cannot meet the technical requirements of next-generation weapon systems and high-thrust launch vehicles.

[0003] Polytriazole resin is a type of polymer that utilizes a 1,3-dipolar cycloaddition reaction of azide and alkynyl groups via click chemistry. Due to the large number of rigid triazole ring structures in the polymer backbone, it exhibits high heat resistance, with a glass transition temperature exceeding 350°C. However, the monomers of polytriazole, aromatic azide compounds, and aromatic alkynyl groups have high molecular structure regularity and rigid molecular chains. Consequently, they remain in a solid state from room temperature to 70°C, making them unsuitable for direct application in the wet winding of carbon fiber shells for solid rocket motors. The conventional method involves dissolving them in a solvent to form a low-viscosity liquid. The addition of solvent severely deteriorates the winding working environment and significantly increases product costs. Most importantly, the addition of solvent easily leads to the formation of bubbles during the subsequent curing process, causing internal defects in the product and potentially resulting in catastrophic quality accidents.

[0004] Therefore, it is necessary to develop a high-temperature resistant resin with a dual-curing system for solid rocket engines to solve the problems of low heat resistance of epoxy resin systems and the inability of polytriazole resin to be directly applied to the wet winding of carbon fiber shells for solid rocket engines. Summary of the Invention

[0005] Based on the above, the purpose of this invention is to provide a high-temperature resistant resin with a dual-curing system for solid rocket engines and its preparation method, overcoming the shortcomings of insufficient heat resistance and poor processability of existing wet winding resin systems, significantly improving the heat resistance of existing epoxy resin systems, thereby improving the heat resistance of carbon fiber shell materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a high-temperature resistant resin with a dual-curing system for solid rocket motors includes the following steps:

[0008] Azide-modified multifunctional epoxy resins were obtained by grafting azide groups onto multifunctional epoxy resins.

[0009] Alkyne-modified aromatic amine epoxy curing agents were obtained by modifying polyfunctional aromatic amines with alkynyl groups.

[0010] Azide-modified multifunctional epoxy resin and alkynyl-modified aromatic amine epoxy curing agent were mixed to obtain a mixed resin. An active diluent, catalyst and accelerator were added, and the mixture was cured using a curing process to obtain a dual-curing system high-temperature resistant resin.

[0011] As a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for solid rocket motors, the grafting method of the azido-based grafted multifunctional epoxy resin involves reacting a portion of the epoxy groups of the multifunctional epoxy resin with sodium azide via an SN2 substitution ring-opening reaction, followed by epichlorohydrin end-capping of the intermediate, thereby obtaining the azido-based modified multifunctional epoxy resin. The reaction mechanism is as follows: Figure 1 As shown; the molar ratio of the sodium azide to the epoxy group of the multifunctional epoxy resin is 1:(1-50).

[0012] As a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for solid rocket motors, the modification method of the alkynyl-modified aromatic amine epoxy curing agent involves an SN2 substitution reaction between the aromatic amine curing agent and propargyl bromide, followed by washing to remove halogens, thereby obtaining the alkynyl-modified aromatic amine epoxy curing agent. The reaction mechanism is as follows: Figure 2 As shown; the molar ratio of the propargyl bromide to the amino active hydrogen of the aromatic amine curing agent is 1:(10-50).

[0013] As a preferred embodiment of a method for preparing a high-temperature resistant resin with a dual-curing system for solid rocket motors, the multifunctional epoxy resin includes one or more of TDE-85 (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester), AFG-90 (trifunctional amino epoxy resin), and AG-80 (tetraglycidylamine epoxy resin); the aromatic amine curing agent includes one or more of m-phenylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, and o-phenylenediamine.

[0014] As a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for solid rocket motors, the active diluent includes one or more of ethylene glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, and trimethylolpropane triglycidyl ether.

[0015] In a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for a solid rocket motor, the reactive diluent is added to adjust the epoxy value of the mixed resin, such that the molar ratio of the azide group to the alkynyl group is (0.98-1.02):1, and the molar ratio of the epoxy group to the amino active hydrogen is (0.95-1.05):1.

[0016] The algorithm for calculating the mass of the added reactive diluent is as follows:

[0017] The mass of the azide-grafted multifunctional epoxy resin is A;

[0018] The mass of the alkynyl-modified aromatic amine epoxy curing agent is B = A * N * M B ;

[0019] The mass of the reactive diluent can be obtained as C = (B*Hn - A*E) A ) / E c ;

[0020] in:

[0021] N-- represents the amount of azide groups contained in 100g of azide-grafted multifunctional epoxy resin;

[0022] C-- represents the amount of alkynyl groups contained in 100g of alkynyl-modified aromatic amine epoxy curing agent;

[0023] Hn represents the amount of amino active hydrogen contained in 100g of alkynyl-modified aromatic amine epoxy curing agent.

[0024] E A --This represents the amount of epoxy groups contained in 100g of azide-grafted multifunctional epoxy resin.

[0025] E c --This represents the amount of epoxy groups contained in 100g of reactive diluent;

[0026] M B -- indicates the molar mass of the acetylene-modified aromatic amine epoxy curing agent.

[0027] In a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for solid rocket motors, the accelerator includes one or more of imidazole, 2-ethyl-4-methylimidazolium, 2-methylimidazolium, and 2-ethylimidazolium; the mass of the accelerator is 0.8 to 1.2% of the mass of the mixed resin.

[0028] In a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for solid rocket motors, the catalyst comprises one or more of triphenylphosphine cuprous bromide and triphenylphosphine cuprous chloride; the mass of the catalyst is 0.2 to 0.5% of the mass of the mixed resin.

[0029] As a preferred embodiment of a method for preparing a dual-curing system high-temperature resistant resin for solid rocket motors, the curing process specifically refers to a multi-step curing process of low-temperature curing, medium-high temperature curing, and high-temperature aging, with the reaction mechanism as follows: Figure 3 As shown.

[0030] Low-temperature curing is the initial reaction between epoxy groups and aromatic amino groups; medium- and high-temperature curing is the addition of alkynyl groups and azide groups to form a polytriazole system; and high-temperature curing is the further reaction between epoxy groups and the remaining amino groups.

[0031] The typical curing regime for the curing process is 65℃ for 180 min, 120℃ for 240 min, and 160℃ for 720 min.

[0032] A high-temperature resistant resin with a dual-curing system for solid rocket motors, prepared by any one of the above-described preparation methods.

[0033] The beneficial effects of this invention are as follows:

[0034] This invention provides a dual-curing system high-temperature resistant resin for solid rocket motors and its preparation method. Based on the chemical structural characteristics of existing epoxy resin systems and heat-resistant polytriazole systems, this invention reduces the molecular regularity of the epoxy resin backbone and polytriazole monomers by grafting polytriazole monomers into the main resin component and curing agent component of the epoxy resin, thereby reducing the system viscosity and improving its process adaptability. During the mixed curing process, the multifunctional epoxy resin and aromatic amine achieve condensation curing of epoxy and amino groups. Simultaneously, under heating conditions, the azide group and the alkynyl group undergo a 1,3-dipolar cycloaddition reaction to generate the polytriazole resin system, thus achieving... The dual-curing of epoxy compounds and polytriazole systems significantly improves the heat resistance of epoxy resin systems. By using accelerators and catalysts, the curing temperature and time are reduced while ensuring the heat resistance of epoxy resins. In addition, the epoxy value of the system is adjusted by using reactive diluents for epoxy resins, thereby simultaneously achieving the stoichiometric ratio of epoxy value to amine value (active hydrogen equivalent) and azide-alkynyl groups in the resin system. This avoids the risks caused by the introduction of solvents, ensures the operability and reliability of wet winding of carbon fiber shells for solid rocket motors, and achieves a high degree of cross-linking of each dual-curing resin system to ensure the overall performance of the resin system.

[0035] The dual-curing system high-temperature resistant resin prepared by this invention can be used for wet winding molding of solid rocket engine casings, and is widely used in applications with extremely stringent requirements for weight, heat resistance and processability, such as composite material nozzle casings for solid rocket engines. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0037] Figure 1 This is a diagram illustrating the grafting reaction mechanism of azide-based multifunctional epoxy resin.

[0038] Figure 2 This is a diagram illustrating the modification reaction mechanism of alkynyl-modified aromatic amine epoxy curing agents;

[0039] Figure 3 This is a schematic diagram of the overall reaction. Detailed Implementation

[0040] To facilitate understanding of the present invention, a more comprehensive description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention. Unless otherwise defined, all technical and scientific terms used in this invention pertain to the technical field of the invention.

[0041] The present invention will be further described below through specific embodiments.

[0042] Example 1

[0043] A method for preparing a high-temperature resistant resin with a dual-curing system for solid rocket motors:

[0044] 10g of TDE-85 resin and 2g of sodium azide were reacted at a temperature of 70℃ for 2.5h. Then, 4g of epichlorohydrin was added to the mixture and reacted at a temperature of 60℃ for 3h to obtain azide-modified multifunctional epoxy resin.

[0045] 10g of m-phenylenediamine and 3g of propargyl bromide were reacted at 60℃ for 4 hours, and then washed to remove halogens to obtain alkynyl-modified polyfunctional aromatic amines.

[0046] If 6.5g of azide-modified multifunctional epoxy resin (A) is added, then the required mass of alkynyl-modified aromatic amine epoxy curing agent (B) is:

[0047] B = A * N * M B

[0048] =6.5g*0.384mol / 100g*120g / mol

[0049] =3g;

[0050] The required mass C of reactive diluent is:

[0051] C = (B*Hn - A*E) A ) / E c

[0052] =(3g*1.975mol / 100g-6.5g*0.85mol / 100g) / 0.8mol / 100g

[0053] =0.5g

[0054] Among them, E A E c It can be determined by titration using the hydrochloric acid-acetone method, referring to GB / T 1677-2008 "Determination of Epoxy Value of Plasticizers"; Hn can be tested by nuclear magnetic resonance (NMR). By measuring the chemical shift of active hydrogen atoms in the compound, its active hydrogen equivalent can be determined. N, C, M B It can also be measured by nuclear magnetic resonance (NMR) and infrared spectroscopy.

[0055] Mix 6.5g of azide-modified multifunctional epoxy resin and 3g of alkynyl-modified multifunctional aromatic amine evenly.

[0056] Add 0.5g of ethylene glycol diglycidyl ether, 0.03g of triphenylphosphine cuprous bromide and 0.1g of 2-methylimidazole to the mixture and stir until homogeneous.

[0057] The mixture is poured into a resin casting mold and cured according to a typical curing regime of 65℃ for 180 min, 120℃ for 240 min, and 160℃ for 720 min.

[0058] After curing, the performance of the casting was tested according to the testing standards, and the test results are shown in Table 1.

[0059] Table 1. Performance test results of the high-temperature resistant resin in the dual-curing system prepared in Example 1.

[0060]

[0061] Example 2

[0062] A method for preparing a high-temperature resistant resin with a dual-curing system for solid rocket motors:

[0063] 10g of AFG-90 resin and 3g of sodium azide were reacted at 68℃ for 3.5h. Then, 3.5g of epichlorohydrin was added to the mixture and reacted at 60℃ for 4h to obtain azide-modified multifunctional epoxy resin.

[0064] 10g of diaminodiphenylmethane and 2.6g of propargyl bromide were reacted at 65℃ for 4 hours. After washing to remove halogen, alkynyl-modified polyfunctional aromatic amines were obtained.

[0065] If 6.5g of azide-modified multifunctional epoxy resin (A) is added, then the required mass of alkynyl-modified aromatic amine epoxy curing agent (B) is:

[0066] B = A * N * M B

[0067] =6.5g*0.199mol / 100g*201g / mol

[0068] =2.6g;

[0069] The required mass C of reactive diluent is:

[0070] C = (B*Hn - A*E) A ) / E c

[0071] =(2.6g*2.38mol / 100g-6.5g*0.9mol / 100g) / 0.7mol / 100g

[0072] =0.5g

[0073] Among them, E A E c It can be determined by titration using the hydrochloric acid-acetone method, referring to GB / T 1677-2008 "Determination of Epoxy Value of Plasticizers"; Hn can be tested by nuclear magnetic resonance (NMR). By measuring the chemical shift of active hydrogen atoms in the compound, its active hydrogen equivalent can be determined. N, C, M B It can also be measured by nuclear magnetic resonance (NMR) and infrared spectroscopy.

[0074] Mix 6.5g of azide-modified multifunctional epoxy resin and 2.6g of alkynyl-modified multifunctional aromatic amine evenly.

[0075] Add 0.5g of trimethylolpropane triglycidyl ether, 0.03g of triphenylphosphine cuprous chloride, 0.05g of 2-methylimidazole and 0.05g of 2-ethyl-4-methylimidazole to the mixture and stir until homogeneous.

[0076] The mixture is poured into a resin casting mold and cured according to a typical curing regime of 65℃ for 180 min, 120℃ for 240 min, and 160℃ for 720 min.

[0077] After curing, the performance of the casting was tested according to the testing standards, and the test results are shown in Table 2.

[0078] Table 2. Performance test results of the high-temperature resistant resin in the dual-curing system prepared in Example 2.

[0079]

[0080]

[0081] Example 3

[0082] A method for preparing a high-temperature resistant resin with a dual-curing system for solid rocket motors:

[0083] 8g of AFG-90 resin, 2g of AG-80 resin, and 3g of sodium azide were reacted at 75℃ for 3.5h. Then, 4g of epichlorohydrin was added to the mixture and reacted at 60℃ for 4h to obtain azide-modified multifunctional epoxy resin.

[0084] 5g of diaminodiphenyl sulfone, 5g of m-phenylenediamine, and 3.5g of propargyl bromide were reacted at 65℃ for 4 hours. After washing to remove halogen, alkynyl-modified polyfunctional aromatic amines were obtained.

[0085] If 6.5g of azide-modified multifunctional epoxy resin (A) is added, then the required mass of alkynyl-modified aromatic amine epoxy curing agent (B) is:

[0086] B = A * N * M B

[0087] =6.5g*0.195mol / 100g*237g / mol

[0088] =3g;

[0089] The required mass C of reactive diluent is:

[0090] C = (B*Hn - A*E) A ) / E c

[0091] =(2.6g*2.38mol / 100g-6.5g*0.9mol / 100g) / 0.7mol / 100g

[0092] =0.5g

[0093] Among them, E A Ec It can be determined by titration using the hydrochloric acid-acetone method, referring to GB / T 1677-2008 "Determination of Epoxy Value of Plasticizers"; Hn can be tested by nuclear magnetic resonance (NMR). By measuring the chemical shift of active hydrogen atoms in the compound, its active hydrogen equivalent can be determined. N, C, M B It can also be measured by nuclear magnetic resonance (NMR) and infrared spectroscopy.

[0094] Mix 6.5g of azide-modified multifunctional epoxy resin and 3g of alkynyl-modified multifunctional aromatic amine evenly.

[0095] Add 0.5g pentaerythritol tetraglycidyl ether, 0.03g triphenylphosphine cuprous chloride, and 0.1g imidazole to the mixture and stir until homogeneous.

[0096] The mixture is poured into a resin casting mold and cured according to a typical curing program: 65℃ for 180 min, 120℃ for 240 min, and 160℃ for 720 min.

[0097] After curing, the performance of the casting was tested according to the testing standards, and the test results are shown in Table 3.

[0098] Table 3. Performance test results of the high-temperature resistant resin in the dual-curing system prepared in Example 3.

[0099]

[0100] The high-temperature resistant resin of the dual-curing system prepared by the embodiments of the present invention shows that the glass transition temperature is effectively improved compared with the prior art, and its mechanical properties meet the application requirements. It can be used for wet winding molding of solid rocket motor shells, ensuring the operability and reliability of wet winding of carbon fiber shells of solid rocket motors, and realizing the high degree of cross-linking of the dual-curing resin system to ensure the comprehensive performance of the resin system.

[0101] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a high-temperature resistant resin with a dual-curing system for solid rocket motors, characterized in that, Includes the following steps: Azide-modified multifunctional epoxy resins were obtained by grafting azide groups onto multifunctional epoxy resins. The grafting method of the azido-based grafted multifunctional epoxy resin is as follows: the intermediate obtained by the SN2 substitution ring-opening reaction of some epoxy groups of the multifunctional epoxy resin with sodium azide is capped with epichlorohydrin to obtain the azido-based modified multifunctional epoxy resin; the molar ratio of sodium azide to the epoxy groups of the multifunctional epoxy resin is 1:(1~50). Alkyne-modified aromatic amine epoxy curing agents are obtained by modifying polyfunctional aromatic amines with alkynyl groups. The modification method of the alkynyl-modified aromatic amine epoxy curing agent is as follows: the aromatic amine curing agent and propargyl bromide undergo an SN2 substitution reaction, followed by washing to remove halogens, thereby obtaining the alkynyl-modified aromatic amine epoxy curing agent. The molar ratio of the amino active hydrogen of the propargyl bromide to that of the aromatic amine curing agent is 1:(10-50). Azide-modified multifunctional epoxy resin and alkynyl-modified aromatic amine epoxy curing agent were mixed to obtain a mixed resin. An active diluent, catalyst and accelerator were added, and the mixture was cured using a curing process to obtain a dual-curing system high-temperature resistant resin.

2. The method for preparing the high-temperature resistant resin of the dual-curing system for solid rocket motors according to claim 1, characterized in that, The multifunctional epoxy resin includes one or more of TDE-85, AFG-90, and AG-80; the aromatic amine curing agent includes one or more of m-phenylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, and o-phenylenediamine.

3. The method for preparing the high-temperature resistant resin of the dual-curing system for solid rocket motors according to claim 1, characterized in that, The active diluent includes one or more of ethylene glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, and trimethylolpropane triglycidyl ether.

4. The method for preparing the high-temperature resistant resin of the dual-curing system for solid rocket motors according to claim 1, characterized in that, The epoxy value of the mixed resin is adjusted by adding the reactive diluent, such that the molar ratio of the azide group to the alkynyl group is (0.98-1.02):1, and the molar ratio of the epoxy group to the amino active hydrogen is (0.95-1.05):

1.

5. The method for preparing the high-temperature resistant resin of the dual-curing system for solid rocket motors according to claim 1, characterized in that, The accelerator includes one or more of imidazole, 2-ethyl-4-methylimidazolium, 2-methylimidazolium, and 2-ethylimidazolium; the mass of the accelerator is 0.8 to 1.2% of the mass of the mixed resin.

6. The method for preparing the high-temperature resistant resin of the dual-curing system for solid rocket motors according to claim 1, characterized in that, The catalyst comprises one or more of triphenylphosphine cuprous bromide and triphenylphosphine cuprous chloride; the mass of the catalyst is 0.2 to 0.5% of the mass of the mixed resin.

7. The method for preparing the high-temperature resistant resin of the dual-curing system for solid rocket motors according to claim 1, characterized in that, The curing process specifically refers to a multi-step curing process of low-temperature curing, medium-high temperature curing, and high-temperature aging. Low-temperature curing is the initial reaction between epoxy groups and aromatic amino groups; medium- and high-temperature curing is the addition of alkynyl groups and azide groups to form a polytriazole system; and high-temperature curing is the further reaction between epoxy groups and the remaining amino groups. The curing process has a curing regime of 65℃ for 180 min, 120℃ for 240 min, and 160℃ for 720 min.

8. A high-temperature resistant resin with a dual-curing system for solid rocket motors, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

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