Preparation method of ammonium perchlorate anti-moisture-absorption material coated with nano-silica particles synergistically modified based on disilane

Abstract

The invention relates to the technical field of AP (ammonium perchlorate) modification, in particular to a preparation method of an ammonium perchlorate anti-moisture-absorption material coated with silicon dioxide based on double-silane synergistic modification through a wet method. Silicon dioxide is subjected to two-step synergistic modification through a long-chain alkylsilane modifier and a short-chain alkylsilane modifier; the preparation method comprises the following steps: modifying the surface by using long-chain silane, filling long-chain silane modified gaps by using short-chain alkyl to prepare modified nano silicon dioxide particles, and coating superfine AP particles with the modified nano silicon dioxide particles through wet modification, the modified nano silicon dioxide particles have enough steric hindrance and better hydrophobicity due to a three-dimensional structure on the surface, and the AP can be effectively prevented from being agglomerated after being coated with the modified nano silicon dioxide particles; the method is green and pollution-free, the process is simple, the comprehensive performance can be easily controlled through simple adjustment, the problem that the ultra-fine AP particles produced industrially are prone to moisture absorption and caking can be solved, and the application range of the ultra-fine AP particles in novel high-energy propellants is widened.

Description

Technical Field

[0001] This invention relates to the field of AP modification technology, specifically to a method for preparing a moisture-resistant material by wet coating of silica based on synergistic modification of bissilane with ammonium perchlorate. Background Technology

[0002] Ammonium perchlorate (AP) is one of the most widely used oxidizers in solid rocket propellants. Ultrafine AP can directly improve its exothermic and safety performance when applied to propellants. Due to its small particle size, ultrafine AP possesses advantages such as high specific surface area and high bulk density, making it a promising candidate for propellant applications. However, its high specific surface area also makes it more susceptible to problems such as moisture absorption and agglomeration in practical applications. Therefore, it is necessary to improve its anti-moisture absorption and anti-agglomeration properties to broaden its application scenarios in propellants.

[0003] Several studies have explored solutions to the problem of moisture absorption and agglomeration in ultrafine alumina (AP). Chinese patent CN119461252A proposes modifying nano-silica with a single silane coupling agent, then wet-coating it onto ultrafine AP, which significantly improves the moisture-proof properties of ultrafine AP; however, its anti-agglomeration performance requires further verification. Another patent, CN110845285B, utilizes polyacrylate to coat AP. After the coated material is placed at 25°C and 100% RH for 24 hours, the moisture absorption rate is tested, showing a 78% reduction compared to pure AP. Regarding composite materials, Wu Guanjie et al. coated AP surfaces with in-situ polymerized HTPB and TDI, resulting in composite particles with significantly improved moisture resistance and packing density. (Wu Guanjie, Ren Quanbin, Hu Chunbo, et al. Performance of powder propellants based on AP pretreatment technology [J]. Energetic Materials, 2017, 25(8): 627-632.) Yu et al. co-coated nanographite and F2603 fluoropolymer onto ultrafine AP to prepare AP@nano-graphite@F2603 microcapsule energetic materials. The hydrophobicity of the material was greatly improved, and the exothermic performance and safety performance were also optimized. (JHYu, Y. Kou, L. Xiao, et al. Efficient construction of core / double-shelledstructured AP@nano-graphite@F2603 energetic microcapsules with lowsensitivity and hygroscopicity [J]. Nanoscale, 2025, 17(5): 2769-2781.) These studies show that surface modification and coating are effective ways to improve the moisture resistance of ultrafine AP.

[0004] The synergistic modification technology of dual silanes has attracted attention due to its ability to combine the advantages of different functional groups. However, silanes are prone to hydrolysis and self-polymerization, forming clusters and resulting in uneven coating layers. This invention regulates the hydrolysis rate of silanes by introducing anti-self-polymerization regulators to prevent self-polymerization caused by the different hydrolytic activities of different introduced silane coupling agents. Furthermore, it utilizes the synergistic effect of long-chain silane coupling agents containing long-chain alkyl groups and short-chain silane coupling agents containing short-chain alkyl groups to construct a sterically hindered hydrophobic layer on the surface of nano-silica. This layer is used to coat modified ultrafine AP particles that possess sufficient anti-agglomeration properties while also exhibiting greater hydrophobicity. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an anti-hygroscopic material based on silane-modified nano-silica particles coated with ammonium perchlorate, so as to solve the problems mentioned in the background art.

[0006] This invention employs a two-step synergistic modification method using a long-chain alkylsilane modifier and a short-chain alkylsilane modifier to modify silica, and introduces an anti-self-polymerization regulator to inhibit inter-silane self-polymerization. This results in modified nano-silica particles, first grafted onto the surface by long-chain alkyl groups and then filled with short-chain alkyl groups. These particles are then applied to ultrafine AP particles via a wet modification process. The modified ultrafine AP particles exhibit improved anti-caking and moisture-absorbing properties. This method is simple, low-cost, and highly safe, preventing moisture absorption and agglomeration of industrially produced ultrafine AP particles, thus expanding its application in novel high-energy propellants.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing an anti-hygroscopic material based on silane-modified nano-silica particles coated with ammonium perchlorate, comprising the following steps:

[0009] (1) The nano silica was uniformly dispersed in ethanol, ethyl acetate, pH regulator and deionized water, and then a long-chain silane coupling agent and an anti-self-polymerization regulator were added to carry out the first step of modification reaction. After a period of reaction, a short-chain silane coupling agent was added to carry out the second step of modification reaction to obtain modified nano silica particles.

[0010] (2) The modified nano-silica particles prepared in step (1) are uniformly dispersed in an organic solution, and then ultrafine AP particles are added and stirred ultrasonically. After removing the organic solution, a moisture-proof material based on bissilane synergistic modified nano-silica particles coated with ammonium perchlorate is obtained. The organic solution is removed by two or three of the following methods: centrifugation, filtration, vacuum drying, oven drying, and freeze drying.

[0011] Further, in step (1), the raw material composition and content of the modified nano silica particles by mass percentage are as follows: nano silica 1~10%, ethanol 30~60%, ethyl acetate 5~30%, pH regulator 5~30%, deionized water 5~30%, long-chain silane coupling agent 1~10%, short-chain silane coupling agent 1~10%, and anti-self-polymerization regulator 0.1~5%.

[0012] Further, in step (1), the particle size of the silicon dioxide is 1~100 nm.

[0013] Further, in step (1), the long-chain silane coupling agent is one or more of the following: dodecyltrimethoxysilane, hexadecyltrimethoxysilane, n-octyltrimethoxysilane, methyldodecyldimethoxysilane, tridecafluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

[0014] Further, in step (1), the short-chain silane coupling agent is one or more of γ-aminopropyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, methacryloxysilane, and γ-glycidoxypropyltrimethoxysilane.

[0015] Further, in step (1), the anti-self-polymerization regulator is one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, polyvinylpyrrolidone, sodium hexametaphosphate, hydroxypropyl methylcellulose, and Tween 20.

[0016] Furthermore, in step (1), the organic solvents ethyl acetate and ethanol can be replaced with one or more of dichloromethane, diethyl ether, isobutanol, and methanol.

[0017] Further, in step (1), the pH regulator is one or more of ammonia, anhydrous acetic acid, dilute hydrochloric acid, and sodium hydroxide.

[0018] Further, in step (1), the temperature of the first step modification reaction is 40-80℃ and the time is 2-6h; the temperature of the second step modification reaction is 20-60℃ and the time is 2-4h.

[0019] Further, in step (2), the mass ratio of the modified nano silica particles to the ultrafine AP particles is 1:200 ~ 1:10, the volume ratio of the ultrafine AP particles to the organic solvent is 1:1 ~ 1:5, and the particle size of the ultrafine AP particles is 50 nm ~ 50 μm.

[0020] Further, in step (2), the organic solvent is one or more of ethyl acetate, dichloromethane, ethanol, diethyl ether, isobutanol, and methanol.

[0021] Further, in step (2), the frequency of the ultrasound is 40 kHz, the power of the ultrasound is 300 W, and the duration of the ultrasound is 1~10 min; the stirring speed is 100~1500 r / min, and the stirring time is 1~10 min.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) This invention synergistically modifies nano-silica particles using two silane coupling agents with different structures, and adds an anti-self-polymerization regulator to prevent self-polymerization between the two silanes. The modified nano-silica is then coated onto ultrafine AP particles using a wet coating method. By adjusting the ratio of long-chain to short-chain groups modified on the surface of the nano-silica, the modified nano-silica can have sufficient steric hindrance while exhibiting greater hydrophobicity. This results in the preparation of ultrafine AP particles that meet specific storage requirements, have sufficient but not excessive steric hindrance, and exhibit better hydrophobicity.

[0024] (2) The modified ultrafine AP particles prepared by this invention use green and pollution-free raw materials, and the process is simple and easy to control. It can utilize the different effects of the two modifiers, and can prepare modified nano-silica particles that meet different performance requirements simply by adjusting the amount of the two modifiers and the amount of the anti-self-agglomeration regulator. The wet mixing process can quickly and uniformly mix the modified nano-silica particles and ultrafine AP particles, and still has high repeatability in large-scale production. Attached Figure Description

[0025] Figure 1 SEM images of modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, 3 and Comparative Example 1; wherein, a is ultrafine AP particles; b, Example 1; c, Example 2; d, Example 3; e, Comparative Example 1;

[0026] Figure 2 Water contact angle of modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, 3 and Comparative Example 1; wherein, a is ultrafine AP particles, b is Example 1, c is Example 2, d is Example 3, and e is Comparative Example 1;

[0027] Figure 3 The moisture absorption rate of the modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, 3 and Comparative Example 1 at 30°C and 91% humidity is shown in the graph.

[0028] Figure 4 Particle size distribution of ultrafine AP particles and modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1 and 2 after storage at 25°C and 60% humidity for 7 days.

[0029] Figure 5 The particle size distribution of modified ultrafine AP particles coated with modified nano-silica prepared in Example 3 and Comparative Example 1 after storage at 25°C and 60% humidity for 7 days.

[0030] Figure 6 This is a flowchart of a method for preparing an anti-hygroscopic material based on silane-coated ammonium perchlorate nanoparticles according to the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Silica, produced by Jiangsu Hehai Nanotechnology Co., Ltd., with an average particle size of 80 nm;

[0033] The ultrafine AP particles were prepared using conventional ultrafine technology in the field, with an average particle size of 4 μm.

[0034] Anhydrous ethanol, produced by Shanghai Aladdin Biochemical Technology Co., Ltd., AR grade;

[0035] Ethyl acetate, produced by Shanghai Aladdin Biochemical Technology Co., Ltd., AR grade;

[0036] Anhydrous acetic acid, produced by Sinopharm Chemical Reagent Co., Ltd., AR grade;

[0037] 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, produced by Sinopharm Chemical Reagent Co., Ltd., AR grade;

[0038] Hexadecyltrimethylammonium bromide, produced by Sinopharm Chemical Reagent Co., Ltd., AR grade;

[0039] Methyltrimethoxysilane, produced by Sinopharm Chemical Reagent Co., Ltd., AR grade;

[0040] Dodecyltrimethoxysilane, produced by Sinopharm Chemical Reagent Co., Ltd., AR grade;

[0041] Sodium dodecyl sulfonate, produced by Sinopharm Chemical Reagent Co., Ltd., AR grade.

[0042] Example 1

[0043] The flowchart of the preparation method of ammonium perchlorate anti-hygroscopic material based on silane synergistic modification of nano-silica particles is shown below. Figure 6 As shown, the specific preparation steps are as follows:

[0044] (1) Take 1 g of nano silica, 10 g of anhydrous ethanol, 5 g of ethyl acetate, 5 g of anhydrous acetic acid, 2 g of deionized water, 2 g of modifier 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 0.3 g of polymerization inhibitor hexadecyltrimethylammonium bromide. Add them to a three-necked flask with a stirrer and a condenser. The stirring speed is 1000 r / min. The temperature is raised to 60℃ and kept for 2 h. Then add 2 g of modifier methyltrimethoxysilane and continue the reaction for 2 h. After the reaction is completed, wash with ethanol several times and put it in a vacuum oven to dry at 60℃ for 24 h to obtain modified nano silica particles with a three-dimensional structure and hydrophobicity on the surface.

[0045] (2) Add 0.4 g of modified nano silica particles to 20 ml of ethanol solution and stir with ultrasonic and magnetic force for 20 min to make them evenly distributed; then add 10 g of ultrafine AP particles, stir with ultrasonic and magnetic force for 10 min, the ultrasonic frequency and power are 40 kHz and 300 W respectively, the stirring speed is 300 rpm, and freeze-dry for 8 h after stirring to obtain modified ultrafine AP particles.

[0046] Example 2

[0047] (1) Take 1 g of silica, 8 g of ethanol, 2 g of ethyl acetate, 3 g of ammonia, 2 g of deionized water, 2 g of modifier dodecyltrimethoxysilane, and 0.3 g of polymerization inhibitor hexadecyltrimethylammonium bromide. Add them to a three-necked flask with a stirrer and a condenser. The stirring speed is 1000 r / min. The temperature is raised to 60℃ and kept at the temperature for 4 h. Then add 2 g of modifier methyltrimethoxysilane and continue to react for 2 h. After the reaction is completed, wash with ethanol several times and put into a vacuum oven to dry at 60℃ for 24 h to obtain modified nano silica particles with a three-dimensional structure and hydrophobicity on the surface.

[0048] (2) Add 0.5 g of modified nano silica particles to 20 ml of ethanol solution and stir with ultrasonic and magnetic force for 20 min to make them evenly distributed; then add 10 g of ultrafine AP particles, stir with ultrasonic and magnetic force for 10 min, the frequency and power of ultrasonic are 40 kHz and 300 W respectively, the stirring speed is 300 rpm, and freeze-dry for 8 h after stirring to obtain modified ultrafine AP particles.

[0049] Example 3

[0050] (1) Take 1 g of silica, 10 g of ethanol, 5 g of ethyl acetate, 3 g of anhydrous acetic acid, 2 g of deionized water, 1 g of modifier 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 0.1 g of polymerization inhibitor sodium dodecyl sulfonate. Add them to a three-necked flask equipped with a stirrer and a condenser. The stirring speed is 1000 r / min. The temperature is raised to 60℃ and kept for 4 h. Then add 1 g of modifier methyltrimethoxysilane and continue the reaction for 2 h. After the reaction is completed, wash with ethanol several times and put into a vacuum oven to dry at 60℃ for 24 h to obtain modified nano silica particles with three-dimensional structure and hydrophobic properties on the surface.

[0051] (2) 0.1 g of modified nano silica particles were added to 20 ml of ethanol solution and ultrasonically and magnetically stirred for 20 min to make them evenly distributed; then 10 g of ultrafine AP particles were added and ultrasonically and magnetically stirred for 10 min. The ultrasonic frequency and power were 40 kHz and 300 W, respectively, and the stirring rate was 300 rpm. After stirring, the particles were freeze-dried for 8 h to obtain modified ultrafine AP particles.

[0052] Comparative Example 1

[0053] (1) Take 1 g of silica, 10 g of ethanol, 5 g of ethyl acetate, 5 g of anhydrous acetic acid, and 2 g of deionized water. Then add 2 g of modifier 1H,1H,2H,2H-perfluorooctyltrimethoxysilane and 2 g of modifier methyltrimethoxysilane. Add them to a three-necked flask with a stirrer and a condenser. The rotation speed is 1000 r / min. The temperature is raised to 60℃ and kept warm for 4 h. After the reaction is completed, wash with ethanol several times and put into a vacuum oven. Dry at 60℃ for 24 h. Because no anti-self-polymerization regulator was added and the modification was not done in two steps, self-polymerization between silanes occurred, resulting in a mixture of self-polymerized gel and unmodified modified nano silica particles.

[0054] (2) Add 0.4 g of the mixture to 20 ml of ethanol solution and stir with ultrasound and magnetic force for 20 min to make it evenly distributed; then add 10 g of ultrafine AP particles, stir with ultrasound and magnetic force for 10 min, the frequency and power of ultrasound are 40 kHz and 300 W respectively, the stirring speed is 300 rpm, and freeze-dry for 8 h after stirring to obtain a mixture of unmodified modified ultrafine AP particles and gel.

[0055] Figure 1(a) is a SEM image of the ultrafine AP particles; (b), (c), and (d) are SEM images of the modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, and 3, respectively; (e) is a SEM image of the mixture of insufficiently modified ultrafine AP particles and colloidal substance prepared in Comparative Example 1; Figure 1 A comparison of the SEM images of embodiments (b), (c), and (d) with the SEM image of the ultrafine AP particles in (a) shows that the modified nano-silica particles were successfully coated onto the ultrafine AP particles through wet modification. Furthermore, they exhibited obvious three-dimensional protrusions on the surface. However, the SEM image of Comparative Example 1 in (e) shows that the lack of an anti-self-polymerization regulator caused the silane coupling agents to self-polymerize, forming irregular gel-like particles, and the coating effect on the ultrafine AP particles was not ideal.

[0056] Figure 2 (a) shows the water contact angle measurement of ultrafine AP particles; (b), (c), and (d) show the water contact angle measurement of modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, and 3, respectively; (e) shows the water contact angle measurement of a mixture of insufficiently modified ultrafine AP particles and a gel prepared in Comparative Example 1. As can be seen from the figures, the water contact angle varies to different degrees depending on the amount, type, and amount of modifier added in each example. However, all examples show a significant improvement compared to the 10.2°±0.2° water contact angle of ultrafine AP particles. Example 2 has the highest water contact angle at 54.6°±1.1°, exhibiting the best hydrophobic performance. Comparative Example 1, being a mixture of a gel and insufficiently modified ultrafine AP particles, has a water contact angle of only 21°±1.7°.

[0057] Figure 3 The graph shows the changes in moisture absorption rate of the modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, and 3, and the mixture of insufficiently modified ultrafine AP particles and gel prepared in Comparative Example 1, stored at 30°C and 91% humidity. As can be seen from the graph, compared to ultrafine AP particles, the moisture absorption performance of each example is improved to varying degrees depending on the amount, type, and quantity of modifier added. Example 2 exhibits the best moisture absorption performance, with a moisture absorption rate of only 0.1103% after 96 hours. The modified nano-silica particles fully cover the surface of the ultrafine AP, effectively preventing it from absorbing moisture through contact with air. Comparative Example 1, due to insufficient coating, has fewer modified nano-silica particles covering the surface of the ultrafine AP, resulting in a weak barrier effect and minimal impact on the moisture absorption rate.

[0058] Figure 4 , Figure 5The particle size distribution of the modified ultrafine AP particles coated with modified nano-silica prepared in Examples 1, 2, and 3, and the mixture of unmodified modified ultrafine AP particles and colloidal material prepared in Comparative Example 1, after storage for 7 days at 25°C and 60% humidity, is shown in the figure. As can be seen from the figure, compared to the ultrafine AP particles, the particle agglomeration phenomenon varies in each example depending on the amount, type, and amount of modifier added. However, the agglomeration phenomenon is significantly reduced compared to the unmodified ultrafine AP particles. This is because, in addition to having higher hydrophobic properties, the three-dimensional structure provides sufficient steric hindrance, which effectively prevents AP agglomeration. Example 2 has the fewest large particles and the best anti-agglomeration effect. Comparative Example 1, due to the presence of colloidal material, actually has more large particles due to interparticle adhesion.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0060] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an anti-hygroscopic material based on silane-synergistic modification of nano-silica particles coated with ammonium perchlorate, characterized in that, Includes the following steps: (1) The nano-silica was uniformly dispersed in ethanol, ethyl acetate, pH regulator and deionized water, and a long-chain silane coupling agent and an anti-self-polymerization regulator were added to carry out the first step of modification reaction. Then a short-chain silane coupling agent was added to carry out the second step of modification reaction to obtain modified nano-silica particles. (2) The modified nano silica particles prepared in step (1) are uniformly dispersed in an organic solution, and then ultrafine AP particles are added and stirred ultrasonically. After the organic solution is removed, a perchlorate anti-hygroscopic material based on silane synergistic modification of nano silica particles is obtained.

2. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with the material according to claim 1, characterized in that, In step (1), the raw material composition and content of the modified nano silica particles by mass percentage are as follows: nano silica 1~10%, ethanol 30~50%, ethyl acetate 5~30%, pH regulator 5~30%, deionized water 5~30%, long-chain silane coupling agent 1~10%, short-chain silane coupling agent 1~10%, and anti-self-polymerization regulator 0.1~5%.

3. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with the material according to claim 1, characterized in that, In step (1), the particle size of the silicon dioxide is 1~100 nm.

4. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with the material according to claim 1, characterized in that, In step (1), the long-chain silane coupling agent is one or more of the following: dodecyltrimethoxysilane, hexadecyltrimethoxysilane, n-octyltrimethoxysilane, methyldodecyldimethoxysilane, tridecafluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

5. The method for preparing an anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with ammonium perchlorate according to claim 1, characterized in that, In step (1), the short-chain silane coupling agent is one or more of γ-aminopropyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, methacryloxysilane, and γ-glycidoxypropyltrimethoxysilane.

6. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with the material according to claim 1, characterized in that, In step (1), the anti-self-polymerization regulator is one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, polyvinylpyrrolidone, sodium hexametaphosphate, hydroxypropyl methylcellulose, and Tween 20; the pH regulator is one or more of ammonia, anhydrous acetic acid, dilute hydrochloric acid, and sodium hydroxide.

7. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with the material according to claim 1, characterized in that, In step (1), the temperature of the first step modification reaction is 40-80℃ and the time is 2-6h; the temperature of the second step modification reaction is 20-60℃ and the time is 2-4h.

8. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles coated with the material according to claim 1, characterized in that, In step (2), the mass ratio of the modified nano-silica particles to the ultrafine AP particles is 1:200 ~ 1:10; the particle size of the ultrafine AP particles is 50 nm ~ 50 μm.

9. The method for preparing an ammonium perchlorate anti-hygroscopic material based on dual-silane synergistic modification of nano-silica particles according to claim 1, characterized in that, In step (2), the organic solvent is one or more of ethyl acetate, dichloromethane, ethanol, diethyl ether, isobutanol, and methanol.

10. The method for preparing an ammonium perchlorate anti-hygroscopic material based on synergistic modification of nano-silica particles by dual silanes according to claim 1, characterized in that, In step (2), the frequency of the ultrasound is 40 kHz, the power of the ultrasound is 300 W, and the duration of the ultrasound is 1 to 10 min; the stirring speed is 100 to 1500 r / min, and the stirring time is 1 to 10 min.

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