Environment-friendly solid propellant with extrusion resistance and preparation method thereof

Abstract

The present application relates to the technical field of solid propellant, and particularly discloses an environment-friendly and extrusion-resistant solid propellant and a preparation method thereof. The solid propellant contains the following raw materials in the mass percentage of 100%: 50-65% oxidizer, 10-15% reducing agent, 15-19% adhesive composition and the rest additives. The solid propellant provided by the present application is safe in composition, simple in process, high in combustion heat, good in extrusion-resistant mechanical property and environment-friendly, and has a good application prospect in the fields of aerospace and military industry.

Description

Technical Field

[0001] This invention relates to the field of solid propellant technology, and specifically discloses an environmentally friendly, extrusion-resistant solid propellant and its preparation method. Background Technology

[0002] Solid propellants are a crucial component of rocket engines, primarily consisting of three parts: oxidizers, reducing agents, and binders. Traditional solid propellants typically contain large amounts of hazardous chemicals, especially high-energy oxidizers and reducing agents. These chemicals pose significant safety risks during production, storage, and use. Furthermore, the production process of traditional propellants is complex and costly, and their combustion produces gases harmful to the environment and human health. Simultaneously, to adapt to the development of strategic and tactical weapons and increasingly complex flight environments, research on solid propellants is growing.

[0003] Chinese patent application CN110950728A discloses a deformable solid propellant and its preparation method, which is prepared from the following raw materials: oxidant, reducing agent, shape memory binder, and plasticizer; the oxidant is ammonium perchlorate or dinitramide; the reducing agent is nano-aluminum powder or magnesium powder; the plasticizer is triethyl acetylacetate; the shape memory binder is an epoxy resin, a curing agent, a catalyst, and an energetic additive; wherein the epoxy resin is bisphenol A epoxy resin, the curing agent is trithiocyanate, the catalyst is 2-methylimidazole, and the energetic additive is polyethylene glycol, and also includes: an alkanolamine complex, an aluminate coupling agent, N,N-diphenyl-p-phenylenediamine, carbon black, and cattocin; this invention uses a shape memory polymer as a binder for the solid propellant, which, without affecting the performance of the binder, gives the propellant a certain degree of deformability, thereby changing the shape of the combustion surface, thereby changing the performance of the engine and better adapting to the flight environment.

[0004] However, this solid propellant has poor storage stability and is prone to moisture absorption and deterioration, affecting its performance. Meanwhile, as solid propellants are developed towards higher energy levels, existing technologies often add high-energy particles, such as aluminum, magnesium, and boron, to solid fuels to increase their energy. However, directly adding metal particles as reducing agents can lead to negative effects such as particle sintering and incomplete combustion, impacting combustion efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses an environmentally friendly, extrusion-resistant solid propellant and its preparation method. The solid propellant provided by this invention features safe components, a simple process, high heat of combustion, good extrusion resistance, and is environmentally friendly, showing promising application prospects in the aerospace and military fields.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides an environmentally friendly, compression-resistant solid propellant, which comprises, by weight percentage, the following raw materials: 50-65% oxidant, 10-15% reducing agent, 15-19% binder composition and the balance being additives.

[0008] In some embodiments of the present invention, the oxidant is at least one of pentaaminotetrazole nitrate, hydrazine nitrate, and thiazine dioxide.

[0009] Preferably, the oxidant is thiazine dioxide.

[0010] In some embodiments of the present invention, the reducing agent is a mixture of carbon black and metallic fuel.

[0011] Preferably, the mass ratio of carbon black to metal fuel is (0.2-0.5):1.

[0012] More preferably, the mass ratio of carbon black to metal fuel is 0.35:1.

[0013] Preferably, the metal fuel is one or a mixture of two or more of aluminum powder, magnesium powder, and boron powder.

[0014] More preferably, the metal fuel is magnesium powder.

[0015] In some embodiments of the invention, the adhesive composition comprises an adhesive and a plasticizer.

[0016] Preferably, the mass ratio of the adhesive to the plasticizer is 1:(1.5-2).

[0017] More preferably, the mass ratio of the adhesive to the plasticizer is 1:1.7.

[0018] In some embodiments of the present invention, the preparation steps of the plasticizer are as follows:

[0019] 2-Ethylhexanol and sebacic acid are mixed and heated to 160–165°C. A catalyst is added, and the temperature is further increased to 200–220°C. The reaction is continued until the acid value of the system is ≤0.20 mg KOH / g. After alcohol removal, cooling, neutralization, and vacuum distillation, the mixture is transferred to a reactor containing hydroxyl-terminated polybutadiene and mixed. An inert atmosphere is introduced, and the temperature is increased to 20–40°C. The mixture is stirred for 1–1.5 h, and then vacuum distilled to obtain the plasticizer.

[0020] In some embodiments of the present invention, the mass ratio of 2-ethylhexanol, sebacic acid and hydroxyl-terminated polybutadiene is (2-2.4):(1-1.2):1.

[0021] Preferably, the mass ratio of 2-ethylhexanol, sebacic acid, and hydroxyl-terminated polybutadiene is 2.2:1.1:1.

[0022] Preferably, the hydroxyl-terminated polybutadiene is a mixture of hydroxyl-terminated polybutadienes with different number-average molecular weights.

[0023] Preferably, the hydroxyl-terminated polybutadiene is a mixture of hydroxyl-terminated polybutadiene with a number average molecular weight of 900-1100 and hydroxyl-terminated polybutadiene with a number average molecular weight of 1500-1700.

[0024] More preferably, the hydroxyl-terminated polybutadiene is a mixture of hydroxyl-terminated polybutadiene with a number average molecular weight of 1000 and hydroxyl-terminated polybutadiene with a number average molecular weight of 1600.

[0025] This invention synthesizes dioctyl sebacate and then modifies it with hydroxyl-terminated polybutadiene to obtain a plasticizer. During the reaction, some carboxyl and hydroxyl groups undergo esterification, achieving the complementary advantages of macromolecular and small-molecule plasticizers. This is likely because the plasticizer, on the one hand, reduces the crystallinity of the molecular chain, and on the other hand, weakens the van der Waals forces between molecular chains by inserting into the molecular chains, thereby increasing mobility. Together, these factors ensure the plasticizing effect of the plasticizer, which is beneficial to improving the mechanical and processing properties of solid propellants. At the same time, it lowers the melting temperature of solid propellants and also gives solid propellants better reprocessability.

[0026] In some embodiments of the present invention, the preparation steps of the adhesive are as follows:

[0027] Bisphenol A type epoxy resin and polyethylene glycol are mixed, and trithiocyanate and 2-methylimidazole are added. The mixture is heated to 45-55°C and reacted for 6-10 hours to obtain the adhesive.

[0028] In some embodiments of the present invention, the mass ratio of the bisphenol A type epoxy resin to polyethylene glycol is 1:(0.5 to 0.8).

[0029] Preferably, the mass ratio of the bisphenol A type epoxy resin to polyethylene glycol is 1:0.65.

[0030] In existing technologies, the network structure between components of solid propellants constructed using commonly used adhesives is not perfect, mainly manifested in the debonding between the reducing agent and other components. This affects the stability of solid propellants to some extent. This invention further modifies commonly used adhesives. The introduction of epoxy groups and rigid imidazole groups increases the network density formed by the adhesive, reducing cracks and pores inside the solid propellant. On the other hand, it increases the modulus and strength of the solid propellant, reducing creep damage. In synergy with plasticizers, it maintains a certain deformation recovery ability and increases stability.

[0031] In some embodiments of the present invention, the additive comprises a curing agent, a coupling agent, and a flame retardant.

[0032] Preferably, the mass ratio of the curing agent, coupling agent and flame retardant is 1:(1-3):(1-1.5).

[0033] Another aspect of the present invention provides a method for preparing an environmentally friendly, compression-resistant solid propellant, comprising the following steps:

[0034] Oxidizing agent, reducing agent and additive are added to the adhesive composition which is preheated to 80-100°C, kept warm and stirred for 1-2 hours, and then transferred to a mold and allowed to stand at room temperature to form, thus obtaining the environmentally friendly and extrusion-resistant solid propellant.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) The environmentally friendly and extrusion-resistant solid propellant prepared by the present invention contains an oxidant, a reducing agent, a binder composition and the balance of additives. Through the optimization design of each component and content in the solid propellant, the solid propellant has better extrusion mechanical properties. At the same time, the solid propellant is safe, simple to process, has high heat of combustion and is environmentally friendly. It has excellent comprehensive performance and good application prospects in the aerospace and military fields.

[0037] (2) By modifying existing plasticizers, this invention achieves the complementary advantages of macromolecular plasticizers and small molecule plasticizers, which is beneficial to improving the mechanical and process properties of solid propellants, reducing the melting temperature of solid propellants, and having excellent mechanical properties and reprocessable performance.

[0038] (3) By further modifying commonly used adhesives, the introduction of epoxy groups and rigid imidazole groups increases the network density formed by the adhesive, thereby reducing cracks and pores inside the solid propellant. On the other hand, it increases the modulus and strength of the solid propellant, thereby reducing creep damage. In synergy with plasticizers, it maintains a certain deformation recovery ability and increases extrusion resistance stability. Detailed Implementation

[0039] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0040] Unless otherwise specified, all reagents used below are readily available from commercial companies.

[0041] Unless otherwise specified, the hydroxyl-terminated polybutadiene used below is obtained by mixing hydroxyl-terminated polybutadiene with a number average molecular weight of 1000 and hydroxyl-terminated polybutadiene with a number average molecular weight of 1600 in a mass ratio of 1:1, and is purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.; the bisphenol A type epoxy resin used is E51; and the polyethylene glycol used is PEG400.

[0042] Unless otherwise specified, the post-processing steps such as "de-alcoholization", "cooling", "neutralization" and "reduced pressure distillation" used below are routine operations for those skilled in the art, and can be selected according to actual operation.

[0043] Preparation Example 1

[0044] The preparation steps of plasticizer are as follows:

[0045] Mix 22g of 2-ethylhexanol and 11g of sebacic acid, heat to 162℃, add 0.3g of methyl titanate, and continue heating to 210℃. When the acid value of the system is ≤0.20mg KOH / g, after alcohol removal, cooling, neutralization and vacuum distillation, transfer to a reactor containing 10g of hydroxyl-terminated polybutadiene and mix. Purge with an inert atmosphere, heat to 30℃, stir for 1.3h, and then distill under vacuum to obtain the plasticizer.

[0046] Preparation Example 2

[0047] The preparation steps for the plasticizer are the same as in Preparation Example 1, except that the amount of sebacic acid added is 13g.

[0048] Preparation Example 3

[0049] The preparation steps of the plasticizer are the same as those in Preparation Example 1, except that the amount of 2-ethylhexanol added is 24.5g.

[0050] Preparation Example 4

[0051] The preparation steps of the adhesive are as follows:

[0052] Mix 10g of bisphenol A epoxy resin and 6.5g of polyethylene glycol, add 1.2g of trithiocyanate and 0.3g of 2-methylimidazole, heat to 50℃, and react for 8 hours to obtain the adhesive.

[0053] Preparation Example 5

[0054] The preparation steps of the adhesive are the same as in Preparation Example 4, except that the amount of polyethylene glycol added is 10g.

[0055] Example 1

[0056] An environmentally friendly, extrusion-resistant solid propellant, by weight percentage, comprises the following raw materials: 57.5% thiazine dioxide, 12.5% ​​reducing agent (obtained by mixing carbon black and magnesium powder in a weight ratio of 0.35:1), 17% binder composition (obtained by mixing binder and plasticizer in a weight ratio of 1:1.7), and the balance additive (obtained by mixing diphenylmethane diisocyanate, KH560 and phosphite in a weight ratio of 1:2:1.2).

[0057] The method for preparing the environmentally friendly, compression-resistant solid propellant in this embodiment includes the following steps:

[0058] Thiazide dioxide, reducing agent, and additives are added to an adhesive composition preheated to 90°C, stirred at this temperature for 1.5 hours, and then transferred to a mold and allowed to stand at room temperature to form an environmentally friendly, extrusion-resistant solid propellant.

[0059] The plasticizer used in this embodiment was obtained from Preparation Example 1, and the adhesive used was obtained from Preparation Example 4.

[0060] Example 2

[0061] An environmentally friendly, extrusion-resistant solid propellant, by weight percentage, comprises the following raw materials: 50% thiazine dioxide, 10% reducing agent (obtained by mixing carbon black and magnesium powder in a weight ratio of 0.35:1), 25% binder composition (obtained by mixing binder and plasticizer in a weight ratio of 1:1.7), and the balance additive (obtained by mixing diphenylmethane diisocyanate, KH560 and phosphite in a weight ratio of 1:2:1.2).

[0062] The method for preparing the environmentally friendly, compression-resistant solid propellant in this embodiment includes the following steps:

[0063] Thiazide dioxide, reducing agent, and additives are added to an adhesive composition preheated to 80°C, stirred at this temperature for 2 hours, and then transferred to a mold and allowed to stand at room temperature to form the final product, thus obtaining an environmentally friendly, extrusion-resistant solid propellant.

[0064] The plasticizer used in this embodiment was obtained from Preparation Example 1, and the adhesive used was obtained from Preparation Example 4.

[0065] Example 3

[0066] An environmentally friendly, extrusion-resistant solid propellant, by weight percentage (100%), comprises the following raw materials: 65% thiazine dioxide, 15% reducing agent (obtained by mixing carbon black and magnesium powder in a weight ratio of 0.35:1), 19% binder composition (obtained by mixing binder and plasticizer in a weight ratio of 1:1.7), and the balance additive (obtained by mixing diphenylmethane diisocyanate, KH560, and phosphite in a weight ratio of 1:2:1.2).

[0067] The method for preparing the environmentally friendly, compression-resistant solid propellant in this embodiment includes the following steps:

[0068] Thiazide dioxide, reducing agent, and additives are added to an adhesive composition preheated to 100°C, stirred at this temperature for 1 hour, and then transferred to a mold and allowed to stand at room temperature to form the final product, thus obtaining an environmentally friendly, extrusion-resistant solid propellant.

[0069] The plasticizer used in this embodiment was obtained from Preparation Example 1, and the adhesive used was obtained from Preparation Example 4.

[0070] Example 4

[0071] An environmentally friendly, compression-resistant solid propellant and its preparation method are disclosed, the difference being that the plasticizer used is obtained from Preparation Example 2.

[0072] Example 5

[0073] An environmentally friendly, compression-resistant solid propellant and its preparation method are disclosed, the difference being that the plasticizer used is obtained from Preparation Example 3.

[0074] Example 6

[0075] An environmentally friendly, compression-resistant solid propellant and its preparation method are disclosed, the difference being that the binder used is obtained from Preparation Example 5.

[0076] Example 7

[0077] An environmentally friendly, extrusion-resistant solid propellant and its preparation method are disclosed, the difference being that the adhesive composition used is obtained by mixing an adhesive and a plasticizer in a mass ratio of 1:2.2.

[0078] Example 8

[0079] An environmentally friendly, compression-resistant solid propellant and its preparation method, the difference being that dioctyl sebacate is used in an equal amount to replace the plasticizer.

[0080] Example 9

[0081] An environmentally friendly, compression-resistant solid propellant and its preparation method, the difference being that polyethylene glycol is used in an equal amount to replace the binder.

[0082] Performance testing

[0083] The solid propellants prepared in Examples 1-9 above were subjected to the following performance tests. The specific test results are shown in Table 1:

[0084] (1) Combustion heat test: The test was conducted according to the energy performance test method in section 2.2.9 of the paper "Preparation and Combustion Performance Study of Novel TAGN Fuel-Rich Solid Propellant" to characterize the combustion efficiency.

[0085] (2) Mechanical properties: The pressure index n was tested according to the gunpowder test method in GJB770B-2005 to characterize the mechanical properties.

[0086] Table 1

[0087] Example 1 11105.1 0.41 Example 2 11084.0 0.38 Example 3 11097.8 0.37 Example 4 11062.7 0.35 Example 5 11057.5 0.33 Example 6 11029.3 0.28 Example 7 11012.1 0.25 Example 8 10904.2 0.21 Example 9 10879.5 0.20

[0088] As shown in Table 1, the solid propellants provided in Examples 1-3 of this invention exhibit high combustion efficiency and stable mechanical properties. A comparison of Examples 4 and 5 with Example 1 reveals that changing the amounts of sebacic acid and 2-ethylhexanol used in preparing the plasticizer affects the mechanical and processing properties of the solid propellant, leading to a decrease in combustion efficiency. A comparison of Example 6 with Example 1 shows that changing the amount of polyethylene glycol used in preparing the adhesive results in insufficient network density, causing a decrease in both combustion efficiency and mechanical properties of the solid propellant. A comparison of Example 7 with Example 1 shows that when the adhesive composition is obtained by mixing the adhesive and plasticizer at a mass ratio of 1:2.2, both combustion efficiency and mechanical properties of the solid propellant decrease, due to weakened deformation recovery and poor stability of the system. A comparison of Example 8 with Example 1 shows that when dioctyl sebate is used to replace the plasticizer in equal amounts, the plasticizing effect is affected by movement restrictions, resulting in a significant decrease in the mechanical properties of the solid propellant. As can be seen from the comparison between Example 9 and Example 1, when polyethylene glycol is used to replace the adhesive in an equal amount, cracks and pores may appear inside the solid propellant, resulting in a decrease in overall performance.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An environmentally friendly, compression-resistant solid propellant, characterized in that, The environmentally friendly, extrusion-resistant solid propellant comprises, by weight percentage, 50-65% oxidant, 10-15% reducing agent, 15-19% binder composition and the balance being additives.

2. The environmentally friendly, compression-resistant solid propellant according to claim 1, characterized in that, The oxidant is at least one of pentaaminotetrazole nitrate, hydrazine nitrate, and thiazine dioxide.

3. The environmentally friendly, compression-resistant solid propellant according to claim 1, characterized in that, The reducing agent is a mixture of carbon black and metallic fuel.

4. The environmentally friendly, compression-resistant solid propellant according to claim 1, characterized in that, The adhesive composition comprises an adhesive and a plasticizer.

5. The environmentally friendly, compression-resistant solid propellant according to claim 4, characterized in that, The preparation steps of the plasticizer are as follows: 2-Ethylhexanol and sebacic acid are mixed and heated to 160–165°C. A catalyst is added, and the temperature is further increased to 200–220°C. The reaction is continued until the acid value of the system is ≤0.20 mg KOH / g. After alcohol removal, cooling, neutralization, and vacuum distillation, the mixture is transferred to a reactor containing hydroxyl-terminated polybutadiene and mixed. An inert atmosphere is introduced, and the temperature is increased to 20–40°C. The mixture is stirred for 1–1.5 h, and then vacuum distilled to obtain the plasticizer.

6. The environmentally friendly, compression-resistant solid propellant according to claim 5, characterized in that, The mass ratio of 2-ethylhexanol, sebacic acid and hydroxyl-terminated polybutadiene is (2-2.4):(1-1.2):

1.

7. The environmentally friendly, compression-resistant solid propellant according to claim 4, characterized in that, The preparation steps of the adhesive are as follows: Bisphenol A type epoxy resin and polyethylene glycol are mixed, and trithiocyanate and 2-methylimidazole are added. The mixture is heated to 45-55°C and reacted for 6-10 hours to obtain the adhesive.

8. The environmentally friendly, compression-resistant solid propellant according to claim 7, characterized in that, The mass ratio of the bisphenol A type epoxy resin to polyethylene glycol is 1:(0.5-0.8).

9. The environmentally friendly, compression-resistant solid propellant according to claim 1, characterized in that, The additives include curing agents, coupling agents, and flame retardants.

10. A method for preparing an environmentally friendly, compression-resistant solid propellant according to any one of claims 1-9, characterized in that, Includes the following steps: Oxidizing agent, reducing agent and additive are added to the adhesive composition which is preheated to 80-100°C, kept warm and stirred for 1-2 hours, and then transferred to a mold and allowed to stand at room temperature to form, thus obtaining the environmentally friendly and extrusion-resistant solid propellant.