Preparation method of composite acid-inhibiting energetic microcapsule by ultrasonic mixing spray drying

Abstract

The application provides a preparation method of composite acid-inhibiting energetic microcapsules by ultrasonic mixing spray drying, and a layer of nano graphite oxide powder is coated on NTO particles based on the spray drying method to prepare a core-shell structure microcapsule with refined particles. The mass fraction ratio of the acid-inhibiting layer nano graphite oxide powder to the core layer NTO particles is 0.1-3%. The composite acid-inhibiting energetic microcapsules prepared by the method provided by the application can effectively inhibit the escape of H ions on the surface of the NTO particles, thereby inhibiting the surface acidity of the NTO, weakening the corrosion effect of the NTO on the metal material of a warhead, realizing effective corrosion protection, and improving the safety of the NTO particles.

Description

Technical Field

[0001] This invention relates to the field of energetic materials technology, and in particular to an ultrasonic mixing spray drying method for preparing composite acid-suppressing energetic microcapsules. Background Technology

[0002] 3-Nitro-1,2,4-triazol-5-one (NTO) is an acid-insensitive energetic material with significant applications in weaponry due to its excellent safety properties. However, the acidity of NTO itself can severely corrode the metal casing of warheads, compromising compatibility and safety. This remains a critical challenge in the field of energetic materials.

[0003] Researchers have used a water suspension method to prepare polymer-coated NTO to obtain molding powder particles, which effectively prevents the acidic release of NTO and reduces its corrosive effect on metals to a certain extent. However, the molding powder particles prepared by the water suspension method have problems such as large particle size and uneven particle size, which easily leads to the formation of a large number of agglomerates. Moreover, the coating surface is relatively rough and easily broken, which affects the acid-suppressing effect after coating.

[0004] Spray drying is a drying method that uses an atomizer to disperse a raw material liquid (such as a solution, suspension, emulsion, or paste) into droplets, and then dries the droplets with a hot gas stream (such as nitrogen, air, or superheated steam) to obtain powdered, granular, agglomerated, or spherical products. It utilizes the compression of nitrogen or steam in the atomizer, ejected from the nozzle at a speed greater than 300 m / s, where the frictional force generated by the velocity difference between the gas and liquid phases breaks the liquid into droplets. This method is highly applicable, can achieve the required small particle size, and has a short processing time, effectively saving preparation time. Spray drying is also highly adaptable, simple to operate, and fully mechanized and automated, with minimal pollution to humans and the environment. Based on this, this invention provides a method for preparing acid-insensitive, non-sensitive composite energetic microcapsules using spray drying. Summary of the Invention

[0005] To effectively solve the above problems, this invention provides an ultrasonic mixing spray drying method for preparing composite acid-suppressing energetic microcapsules. The objective of this invention is achieved through the following means:

[0006] A method for preparing composite acid-suppressing energetic microcapsules by ultrasonic mixing and spray drying includes the following steps:

[0007] (1) Preparation of nano-graphite oxide dispersion: A mixture of deionized water and / or anhydrous ethanol was added to a certain mass of nano-graphite oxide particles, stirred and then ultrasonically dispersed to prepare nano-graphite oxide dispersion.

[0008] (2) Preparation of supersaturated NTO aqueous suspension: Take an excess of NTO particles, add a mixture of deionized water and / or anhydrous ethanol, stir and let stand, then take the supernatant to prepare a saturated NTO aqueous solution. Take a fixed amount of NTO particles and add a small amount of saturated NTO solution to obtain a supersaturated NTO aqueous suspension;

[0009] (3) Ultrasonic mixing: Nano-graphite oxide dispersion is poured into a container containing supersaturated NTO suspension in sequence within a certain time period and ultrasonic mixing is performed;

[0010] (4) Preparation of composite acid-suppressing energetic microcapsules by spray drying:

[0011] The uniformly dispersed suspension from step (3) is added to a spray dryer, the nitrogen flow rate is adjusted, and then the heating system and induced draft fan are turned on, setting a certain inlet and outlet temperature. The resulting composite acid-suppressing energetic microcapsule material is then collected into a sample vial.

[0012] Preferably, the nano-graphite oxide particles in step (1) have a particle size of 0.5–5 μm and a thickness of 0.8–1.2 nm;

[0013] Preferably, the mass-to-volume ratio of the nano-graphite oxide powder to deionized water and / or anhydrous ethanol solution in step (1) is (0.05-1) g: (50-1000) mL, and the volume ratio of deionized water to anhydrous ethanol is 0.01-1.

[0014] Preferably, the stirring speed in step (1) is 300–600 r / min, and the stirring time is 5–30 min.

[0015] Preferably, the ultrasonic frequency and power in step (1) are 20kHz and 800W respectively, the ultrasonic time is 3 to 40 minutes, and the ultrasonic temperature is 35 to 75℃.

[0016] Preferably, the size of the NTO micron particles in step (2) is in the range of 10 to 1000 μm.

[0017] Preferably, the purity of the NTO particles described in step (2) is ≥98%.

[0018] Preferably, the mass-to-volume ratio of the excess NTO particles to the solution in step (2) is (10-60) g: (100-1000) mL;

[0019] Preferably, the volume ratio of deionized water to anhydrous ethanol in the mixed solution described in step (2) is 0 to 1;

[0020] Preferably, the stirring speed in step (2) is 100-300 r / min, the stirring time is 5-30 min, and the settling time is 10-120 min;

[0021] Preferably, the mass-volume ratio of the quantitative NTO particles to the small amount of NTO saturated solution in step (2) is (10-30) g: (30-50) mL;

[0022] Preferably, the solid content mass ratio in the supersaturated NTO suspension and the nano-graphite oxide dispersion in step (3) is (10-30) g: (0.05-1) g;

[0023] Preferably, the dropping rate in step (3) is 3 to 15 mL / min;

[0024] Preferably, the frequency and power of the ultrasonic mixing in step (3) are 20kHz and 800W, the ultrasonic time is 10-60min, and the ultrasonic temperature is 30-60℃.

[0025] Preferably, nitrogen gas is introduced into the spray drying process in step (4) at a flow rate of 4 to 10 L / min;

[0026] Preferably, the inlet temperature in the spray drying process described in step (4) is 80–120°C;

[0027] Preferably, the outlet temperature in the spray drying process described in step (4) is 55-75°C.

[0028] Compared with the prior art, the ultrasonic mixing and spray drying method for preparing composite acid-suppressing energetic microcapsules described above has the following advantages:

[0029] 1. This invention provides a rapid and simple preparation method that can effectively suppress the acidic escape from the NTO surface and achieve effective corrosion protection for the metal shell of the warhead;

[0030] 2. The nano-graphite oxide in this invention has a large specific surface area and good thermal conductivity. The NTO particles uniformly coated with the prepared graphite oxide can effectively improve thermal stability.

[0031] 3. In this invention, the particle size of NTO can be refined by controlling the inlet and outlet temperatures of the spray dryer, which further ensures that the prepared energetic microcapsule material has low impact sensitivity and friction sensitivity. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0033] Figure 1a This is the initial NTO particle size distribution diagram;

[0034] Figure 1b This is the particle size distribution diagram of the composite acid-suppressing energetic microcapsules prepared in Example 4;

[0035] Figure 2 This is a microscopic morphology diagram of the composite acid-suppressing energetic microcapsules prepared in Example 2. Detailed Implementation

[0036] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0037] Example 1:

[0038] According to the technical solution of the present invention, the ultrasonic mixing spray drying preparation method of composite acid-suppressing energetic microcapsules includes the following steps:

[0039] (1) Preparation of nano-graphite oxide dispersion: 0.1gn nano-graphite oxide particles were added to a mixed solution of 50mL deionized water and ethanol (volume ratio 1:1), stirred at 300r / min for 10min, and then placed in an ultrasonic disperser for ultrasonic dispersion for 10min. The ultrasonic frequency and power were 20kHz and 800W, respectively, and the ultrasonic temperature was 35℃, to obtain a uniformly dispersed nano-graphite oxide dispersion.

[0040] (2) Preparation of supersaturated NTO aqueous suspension: Take 10g of NTO particles with a particle size of 120μm and put them into an Erlenmeyer flask. Add 100mL of deionized water and stir at 100r / min for 20min. Let it stand for 30min and take the supernatant to obtain a saturated NTO solution. Then take 20g of NTO particles into a small beaker and add 30mL of deionized water to obtain a supersaturated NTO aqueous suspension.

[0041] (3) Ultrasonic mixing: Add the nano-graphite oxide dispersion prepared in step (1) to the supersaturated NTO aqueous suspension prepared in step (2) at a dropping rate of 3 mL / min, and then perform ultrasonic mixing at a frequency and power of 20 kHz and 800 W, with the ultrasonic time set to 20 min and the ultrasonic temperature set to 30 ℃.

[0042] (4) Preparation of composite acid-suppressing energetic microcapsules by spray drying:

[0043] The ultrasonically dispersed suspension from step (3) was added to a spray dryer, and the nitrogen flow rate was adjusted to 6 L / min. Then, the heating system and induced draft fan were turned on, and the inlet temperature was set to 85°C and the outlet temperature to 60°C. The resulting composite acid-suppressing energetic material microcapsules were then collected into sample vials.

[0044] Example 2

[0045] According to the technical solution of the present invention, the ultrasonic mixing spray drying preparation method of composite acid-suppressing energetic microcapsules includes the following steps:

[0046] (1) Preparation of nano-graphite oxide dispersion: 0.2 g of nano-graphite oxide particles were added to 100 mL of a mixed solution of deionized water and ethanol (volume ratio 0.01), stirred at 350 r / min for 15 min, and then placed in an ultrasonic disperser for ultrasonic dispersion for 10 min. The ultrasonic frequency and power were 20 kHz and 800 W, respectively, and the ultrasonic temperature was 40 °C, to obtain a uniformly dispersed nano-graphite oxide dispersion.

[0047] (2) Preparation of supersaturated NTO aqueous suspension: Take 20g of NTO particles with a particle size of 140μm and put them in an Erlenmeyer flask. Add 200mL of deionized water and stir at 150r / min for 15min. Let it stand for 20min and take the supernatant to obtain a saturated NTO solution. Then take 15g of NTO particles in a small beaker and add 20mL of deionized water to obtain a supersaturated NTO aqueous suspension.

[0048] (3) Ultrasonic mixing: Add the nano-graphite oxide dispersion prepared in step (1) to the supersaturated NTO aqueous suspension prepared in step (2) at a dropping rate of 5 mL / min, and then perform ultrasonic mixing at a frequency and power of 20 kHz and 800 W, with the ultrasonic time set to 25 min and the ultrasonic temperature set to 35 ℃.

[0049] (4) Preparation of composite acid-suppressing energetic microcapsules by spray drying:

[0050] The ultrasonically dispersed suspension from step (3) was added to a spray dryer, and the nitrogen flow rate was adjusted to 5 L / min. The heating system and induced draft fan were then turned on, and the inlet temperature was set to 80℃ and the outlet temperature to 55℃. The resulting composite acid-suppressing energetic material microcapsules were then collected into sample vials. The microstructure is shown in the image below. Figure 2 As shown.

[0051] Example 3

[0052] According to the technical solution of the present invention, the ultrasonic mixing spray drying preparation method of composite acid-suppressing energetic microcapsules includes the following steps:

[0053] (1) Preparation of nano-graphite oxide dispersion: 0.08 g of nano-graphite oxide particles were added to a mixed solution of 50 mL of deionized water and ethanol (volume ratio 0.05), stirred at 300 r / min for 10 min, and then placed in an ultrasonic disperser for ultrasonic dispersion for 20 min. The ultrasonic frequency and power were 20 kHz and 800 W, respectively, and the ultrasonic temperature was 35 °C, to obtain a uniformly dispersed nano-graphite oxide dispersion.

[0054] (2) Preparation of supersaturated NTO aqueous suspension: Take 30g of NTO particles with a particle size of 150μm and put them in an Erlenmeyer flask. Add 300mL of deionized water and stir at 250r / min for 25min. Let it stand for 30min and take the supernatant to obtain a saturated NTO solution. Then take 25g of NTO particles in a small beaker and add 30mL of deionized water to obtain a supersaturated NTO aqueous suspension.

[0055] (3) Ultrasonic mixing: Add the nano-graphite oxide dispersion prepared in step (1) to the supersaturated NTO aqueous suspension prepared in step (2) at a dropping rate of 8 mL / min, and then perform ultrasonic mixing at a frequency and power of 20 kHz and 800 W, with the ultrasonic time set to 35 min and the ultrasonic temperature set to 40 °C.

[0056] (4) Preparation of composite acid-suppressing energetic microcapsules by spray drying:

[0057] The ultrasonically dispersed suspension from step (3) was added to a spray dryer, and the nitrogen flow rate was adjusted to 6 L / min. Then, the heating system and induced draft fan were turned on, and the inlet temperature was set to 90°C and the outlet temperature to 65°C. The resulting composite acid-suppressing energetic material microcapsules were then collected into sample vials.

[0058] Example 4

[0059] According to the technical solution of the present invention, the ultrasonic mixing spray drying preparation method of composite acid-suppressing energetic microcapsules includes the following steps:

[0060] (1) Preparation of nano-graphite oxide dispersion: 1 g of nano-graphite oxide particles were added to a mixed solution of 500 mL of deionized water and ethanol (volume ratio 0.08), stirred at 600 r / min for 30 min, and then placed in an ultrasonic disperser for ultrasonic dispersion for 40 min. The ultrasonic frequency and power were 20 kHz and 800 W, respectively, and the ultrasonic temperature was 65 °C, to obtain a uniformly dispersed nano-graphite oxide dispersion.

[0061] (2) Preparation of supersaturated NTO aqueous suspension: Take 50g of NTO particles with a particle size of 200μm and put them in an Erlenmeyer flask. Add 300mL of anhydrous ethanol and stir at 350r / min for 30min. Let stand for 60min and take the supernatant to obtain a saturated NTO solution. Then take 30g of NTO particles in a small beaker and add 50mL of deionized water to obtain a supersaturated NTO aqueous suspension.

[0062] (3) Ultrasonic mixing: Add the nano-graphite oxide dispersion prepared in step (1) to the supersaturated NTO aqueous suspension prepared in step (2) at a dropping rate of 12 mL / min, and then perform ultrasonic mixing at a frequency and power of 20 kHz and 800 W, with the ultrasonic time set to 45 min and the ultrasonic temperature set to 50 °C.

[0063] (4) Preparation of composite acid-suppressing energetic microcapsules by spray drying:

[0064] The ultrasonically dispersed suspension from step (3) was added to a spray dryer, and the nitrogen flow rate was adjusted to 8 L / min. The heating system and induced draft fan were then turned on, and the inlet temperature was set to 110℃ and the outlet temperature to 75℃. The resulting composite acid-suppressing energetic material microcapsules were then collected into sample vials. The particle size distribution of the initial NTO particles and the prepared composite acid-suppressing energetic microcapsules was compared as follows: Figure 1a and Figure 1b As shown.

[0065] Effect verification

[0066] I. The particle size of the energetic microcapsules and NTO particles prepared in Example 4 was measured, and the microstructure of the energetic microcapsules prepared in Example 2 was characterized. The results showed that, compared with NTO particles, the particle size of the energetic microcapsules prepared in Example 4 was reduced, and the particle size distribution range decreased to 2-7 micrometers. The reduction in particle size is beneficial to reducing the sensitivity of the energetic material and improving safety performance. The energetic microcapsules prepared in Example 2 exhibited a very uniform core-shell microcapsule structure, with a layer of nanoparticles uniformly coated on the surface of NTO particles. This effectively suppressed the acidity emanating from the NTO particles, reduced the corrosive effect of H ions on the metal, and comprehensively improved the performance of the energetic material.

[0067] 2. Weigh 5g of NTO particles and the composite acid-suppressing energetic microgels prepared by the method provided in Examples 1-4 above into 100mL beakers respectively, stir evenly and let stand, take the supernatant to test the pH value of the solution, and the results are shown in Table 1.

[0068] As can be seen from Table 1, NTO particles have a low pH value and exhibit strong acidity. Compared with NTO particles, the composite acid-suppressing energetic microcapsule materials prepared using the method provided by this invention in Examples 1-4 show a significant increase in pH value, indicating a reduction in acidity. The method provided by this invention effectively inhibits the acidic release from NTO particles and reduces the corrosive effect on metals.

[0069] Table 1. pH values ​​of NTO particles and composite acid-suppressing energetic microcapsules from Examples 1-4

[0070] Sample solution (5g / 100mL) pH value (average of three values) Example 1 5.21 Example 2 5.14 Example 3 5.07 Example 4 5.96 NTO 3.6

[0071] III. The impact sensitivity and friction sensitivity of the composite acid-suppressing energetic microcapsules and NTO particles prepared in Examples 1 to 4 were determined according to the explosion percentage method in GJB772A-79. The results are listed in Table 2.

[0072] As can be seen from the results in Table 2, compared with NTO particles, the impact sensitivity and friction sensitivity of the composite acid-suppressing energetic microcapsule material prepared by the method provided by the present invention are reduced. This indicates that the method provided by the present invention can obtain energetic microcapsules with good safety properties, which can be widely used in penetrating warheads with stringent safety requirements.

[0073] Table 2. Mechanical sensitivity of NTO particles and composite acid-suppressing energetic microcapsules prepared in Examples 1-4

[0074] sample Impact sensitivity (%) Friction sensitivity (%) Example 1 2 3 Example 2 3 5 Example 3 4 4 Example 4 5 4 NTO 10 12

[0075] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for the production of composite acid-encapsulated energetic microcapsules by ultrasonic mixing spray drying, characterized in that A layer of nano-graphite oxide powder is coated onto NTO particles using a spray drying method; Includes the following steps: (1) Preparation of nano-graphite oxide dispersion: Add a mixture of deionized water and / or anhydrous ethanol to nano-graphite oxide particles, stir and then ultrasonically disperse to prepare nano-graphite oxide dispersion. (2) Preparation of supersaturated NTO aqueous suspension: Take an excess of NTO particles, add a mixture of deionized water and / or anhydrous ethanol, stir and let stand, and take the supernatant to prepare a saturated NTO aqueous solution; then take a quantitative amount of NTO particles and add a small amount of NTO saturated solution to obtain a supersaturated NTO aqueous suspension. (3) Ultrasonic mixing: Pour nano-graphite oxide dispersion into a container containing supersaturated NTO suspension and mix ultrasonically; (4) Preparation of composite acid-suppressing energetic microcapsules by spray drying: Add the uniformly dispersed suspension in step (3) to the spray dryer, adjust the nitrogen flow rate, and then turn on the heating system and the blower, and set the inlet temperature and outlet temperature; then, collect the obtained composite acid-suppressing energetic microcapsule material into the sample bottle.

2. The process for the preparation of composite acid- suppressing energetic microcapsules by ultrasonic mixing spray drying according to claim 1, characterized in that, In step (1), the particle size of the nano-graphite oxide is 0.5~5μm and the thickness is 0.8~1.2nm; the mass-to-volume ratio of nano-graphite oxide powder to deionized water and / or anhydrous ethanol solution is 0.05~1g:50~1000mL, and the volume ratio of deionized water to anhydrous ethanol is 0.01~1; the stirring speed is 300~600r / min and the stirring time is 5~30min.

3. The process for the preparation of composite acid-encapsulated energetic microcapsules by ultrasonic mixing spray drying according to claim 1, characterized in that, In step (1), the ultrasonic frequency and power are 20kHz and 800W respectively, the ultrasonic time is 3~40min, and the ultrasonic temperature is 35~75℃.

4. The method for preparing composite acid-suppressing energetic microcapsules by ultrasonic mixing and spray drying according to claim 1, characterized in that, In step (2), the size of the NTO micron particles is in the range of 10~1000μm, the purity of the NTO particles is ≥98%, the mass-volume ratio of the excess NTO particles to the solution is 10~60g:100~1000mL, and the volume ratio of deionized water to anhydrous ethanol in the mixed solution is 0~1.

5. The process for the preparation of composite acid-encapsulated energetic microcapsules by ultrasonic mixing spray drying according to claim 1, characterized in that, In step (2), the stirring speed is 100~300r / min, the stirring time is 5~30min, and the standing time is 10~120min; the mass volume of the quantitative NTO particles and the small amount of NTO saturated solution is 10~30g:30~50mL.

6. The method for preparing composite acid-suppressing energetic microcapsules by ultrasonic mixing and spray drying according to claim 1, characterized in that, In step (3), the mass ratio of solids in the supersaturated NTO suspension and the nano-graphite oxide dispersion is 10~30g:0.05~1g; the dropping speed is 3~15mL / min; the ultrasonic mixing frequency and power are 20kHz and 800W, the ultrasonic time is 10~60min, and the ultrasonic temperature is 30~60℃.

7. The process for the preparation of composite acid-encapsulated energetic microcapsules by ultrasonic mixing spray drying according to claim 1, characterized in that, In step (4), nitrogen gas is introduced into the spray drying process at a flow rate of 4~10L / min, an inlet temperature of 80~120℃, and an outlet temperature of 55~75℃.

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