Method for preparing spherical 5, 5-azotetrazole zinc

Abstract

The invention discloses a method for preparing spherical zinc azotetrazole, which comprises the following steps: adding a base solution and zinc azotetrazole particles with a certain particle size as seed crystals into a container, stirring and adding a zinc salt solution and a sodium azotetrazole solution at a certain temperature, and reacting for a period of time to obtain the spherical zinc azotetrazole. The method does not need to introduce an additional crystal form control agent and control the pH of the solution to control crystallization. The obtained zinc azotetrazole particles are spheroidized, the free-running property and the apparent bulk density are greatly improved, and by controlling the particle size of the added seed crystal, the preparation of the large spherical zinc azotetrazole particles with the particle size range of 80-200 microns can be realized.

Description

Technical Field

[0001] The invention belongs to the field of energetic material crystallization, and in particular relates to a method for preparing spherical 5,5'-azotetrazolyl zinc (ZnATZ). Background Art

[0002] 5,5'-Zinc azotetrazolyl is a detonating agent that does not contain toxic metals or environmentally harmful components such as perchlorate. Sun Yanling, Zhu Shunguan, et al. published a method for synthesizing zinc azotetrazolyl (Sun Yanling, Yan Donglin, Zhu Shunguan, et al. Synthesis and characterization of 5,5'-zinc azotetrazolyl[J]. Energetic Materials, 2012, 20(3):5.). The target compound ZnATZ is synthesized in two steps. First, 5-aminotetrazolyl is used as a raw material and oxidized to generate sodium 5,5-azotetrazolyl (NaATZ) by the Thiele alkaline oxidation method. 5,5'-Zinc azotetrazolyl is synthesized from pentaaminotetrazolyl as a raw material. It does not contain toxic metals or environmentally harmful components such as perchlorate. Its decomposition products are only zinc oxide and nitrogen. Compared with the traditional detonating agent lead styphnate, zinc azotetrazolyl has comparable flame sensitivity, impact sensitivity and electrostatic sensitivity, and is expected to replace lead styphnate as a component of green detonating agent. However, the zinc azotetrazolyl prepared by the above-mentioned synthesis method has the problem of poor dispersibility and low bulk density. In the process of forming a formula agent by mixing with other ingredients, it is not easy for other ingredients to be mixed evenly and easily causes the mixed agent to be layered. In addition, in the process of charging, it is easy to produce floating medicine, which brings safety problems. The crystal morphology of zinc azotetrazolyl prepared by the above-mentioned method presents a flower-like shape formed by the accumulation of sheet crystals, and the agent particles are not dense, which is one of the reasons causing the smaller bulk density and higher sensitivity. In addition, since zinc azotetrazolyl is insoluble in common solvents such as water, it brings difficulties to the controlled crystallization process, so the crystal morphology and particle size of zinc azotetrazolyl for the use of the detonator are of great significance. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing spherical azotetrazole zinc. By preparing spherical azotetrazole zinc, the problems of low bulk density, poor fluidity and high sensitivity of the azotetrazole zinc obtained by the existing preparation method are successfully solved.

[0004] The invention discloses a method for preparing spherical zinc azotetrazole. The method comprises the following steps: adding a base liquid and zinc azotetrazole particles with a certain particle size as crystal seeds into a container, adding a zinc salt solution and a sodium azotetrazole solution under stirring at a certain temperature, and reacting for a period of time to obtain the spherical zinc azotetrazole.

[0005] Preferably, the zinc azotetrazolyl particles of a certain particle size refer to particles having a particle size not greater than 100 microns.

[0006] Preferably, the base liquid is water.

[0007] Preferably, the mass ratio of zinc azotetrazole particles of a certain particle size to the base liquid is 0.08:60.

[0008] Preferably, the certain temperature is 50-75°C, preferably 65-75°C.

[0009] Preferably, the time for adding the zinc salt solution is controlled within 20-30 minutes.

[0010] Preferably, the time for adding the sodium azotetrazolyl solution is controlled within 25-35 minutes.

[0011] Preferably, the reaction time is 10-20 minutes.

[0012] Compared with the prior art, the method does not need to introduce additional crystal form control agents, and does not need to control the pH of the solution to control crystallization. The obtained zinc azotetrazolyl particles are spheroidized, and the fluidity and loose packing density are greatly improved. By controlling the particle size of the added seed crystals, the preparation of large-particle spherical zinc azotetrazolyl with a particle size range of 80-200 μm can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The effect of different seed contents on the crystal morphology.

[0014] Figure 2 The effect of different temperatures on the crystal morphology.

[0015] Figure 3 The effect of different feeding time on the crystal morphology.

[0016] Figure 4 The morphology comparison of zinc azotetrazolyl: (a) literature method, (b) the method of the present invention. DETAILED DESCRIPTION

[0017] The present disclosure may be more easily understood by reference to the following description in conjunction with the accompanying drawings and examples, all of which constitute a part of the present disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described and / or shown herein. Further, the terms used herein are only used for the purpose of describing specific embodiments by way of example and are not intended to be limiting unless otherwise stated.

[0018] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically not included, each separate embodiment is considered to be combinable with any other embodiment, and the combination is considered to represent another different embodiment. Conversely, for the sake of simplicity, the various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or substructure itself may also be considered to be an independent embodiment.

[0019] Example 1

[0020] Weigh 1.72g of zinc acetate dihydrate and 1.78g of sodium azotetrazole and dissolve them in 60ml of aqueous solution respectively, add 60ml of deionized water into a chemical combiner, add 40mg, 60mg, 80mg and 100mg of seed crystals respectively, start stirring to heat the base liquid to 65°C, and add the materials separately with a peristaltic pump. Add the zinc acetate dihydrate solution first for 1min and then start adding the sodium azotetrazole solution. Add the zinc acetate dihydrate in 20min and the sodium azotetrazole in 30min. After the feeding is completed, keep the reaction warm for 10min, then cool and filter, wash and dry.

[0021] Table 1. Packing density and repose angle at different seed contents

[0022]

[0023]

[0024] Note: A-feeding time of zinc acetate solution; B-feeding time of zinc tetrazolyl; A`-feeding time of zinc acetate solution before sodium tetrazolyl solution; M-content of added seed crystals; ρ-loose bulk density; θ-angle of repose

[0025] As can be seen from Table 1, the presence of seed crystals has a significant effect on the loose bulk density and the angle of repose. When the seed crystal content is 80 mg, the prepared spherical zinc azotetrazole has the largest loose bulk density, and the angle of repose indicates that the fluidity is the best at this time. Figure 1 The ZnATZ morphology in the image shows that after adding seed crystals, the ZnATZ morphology changes and presents a spherical flower state. When the seed crystal content is 80 mg, the particle size of ZnATZ in the scanning electron microscope field of view presents better uniformity.

[0026] Example 2

[0027] Dissolve 1.72g of zinc acetate dihydrate and 1.78g of sodium tetrazolyl chloride in 60ml of aqueous solution, add 60ml of deionized water to the chemical combiner, add 80mg of seed crystals, start stirring to heat the bottom solution to different temperatures, and then add the materials separately with a peristaltic pump. Add the zinc acetate dihydrate solution for 1min first and then start adding the sodium tetrazolyl chloride solution. Add the zinc acetate dihydrate for 20min and the sodium tetrazolyl chloride for 30min. After the addition is completed, keep the reaction warm for 10min, then cool and filter, wash and dry. The effect of higher temperature on the crystallization of spherical zinc tetrazolyl chloride was investigated. The crystal morphology, bulk density and flowability data are shown in Table 2 and Figure 2 Shown:

[0028] Table 2. Packing density and repose angle at different seed contents

[0029]

[0030] Note: T-reaction temperature; ρ-loose bulk density; θ-angle of repose

[0031] As shown in Table 2, under the reaction conditions of 65°C and 70°C, the differences in bulk density and repose angle of the obtained products are negligible, indicating that the products under both conditions have good bulk density and fluidity. However, under the reaction condition of 75°C, the fluidity and bulk density of the obtained products are worse.

[0032] Depend on Figure 2 It can be seen that at three different temperatures, the size of the spheroidized zinc tetrazolyl particles is uniform, but the surface morphology of the particles is different. Under the reaction condition of 75℃, the zinc tetrazolyl particles are not round, but are generally jagged, while under the reaction conditions of 65℃ and 70℃, the particles appear more round, and at 70℃, the surface is smoother.

[0033] Example 3

[0034] Under the conditions of 80 mg seed content and 70 °C reaction temperature, in order to simplify the feeding method and explore the effect of feeding time on crystallization, different feeding times (20:30, 30:30, 30:0) were set for zinc acetate solution (A) and sodium tetrazolyl solution (B). When the feeding time was 0:30, the reaction solution was an emulsion after the feeding was completed, and no product was obtained. Crystal morphology, bulk density and flowability data are shown in Figure 2. Figure 3 As shown in Table 3:

[0035] Depend on Figure 3 It can be seen that when the zinc acetate solution is first added, the obtained zinc azotetrazole particles are uniform, the morphology is relatively regular, and they are close to spherical. However, when sodium azotetrazole is used as the base liquid, the reaction solution eventually becomes an emulsion and is difficult to filter, and large particles of zinc azotetrazole cannot be obtained.

[0036] Table 3. Bulk density and angle of repose at different feeding times

[0037]

[0038] Note: A:B-feeding time ratio of zinc acetate solution and sodium tetrazolyl solution; ρ-loose bulk density; θ-repose angle

[0039] As shown in Table 3, as the addition time of zinc acetate solution (A) increases, the bulk density of the obtained zinc tetrazolyl gradually increases and the angle of repose gradually decreases. When the addition time of the two solutions is 30 minutes, the flower-shaped zinc tetrazolyl has the largest bulk density and the smallest angle of repose, indicating that under this condition, the product has the best fluidity and the largest bulk density. The morphology of ZnATZ obtained under this condition is compared with that of ZnATZ obtained according to the literature method. Figure 4 The ZnATZ prepared by this method clearly presents a spherical state, and the particle size is increased from 20μm in the literature method to 100μm. The repose angle shows that the fluidity of the ZnATZ prepared by this method is greatly improved.

Claims

1. A method for preparing spherical zinc azotetrazole, characterized in that: Add the bottom liquid and zinc azotetrazole particles of a certain particle size as seed crystals into a container, add the zinc salt solution and sodium azotetrazole solution under stirring at a certain temperature, and obtain spherical zinc azotetrazole after a period of reaction.

2. The method according to claim 1, characterized in that The zinc azotetrazolyl particles with a certain particle size refer to particles having a particle size of no more than 100 microns.

3. The method according to claim 1, characterized in that The base liquid is water.

4. The method according to claim 1, characterized in that The mass ratio of zinc azotetrazolyl particles of a certain particle size to the base liquid is 0.08:

60.

5. The method according to claim 1, characterized in that The certain temperature refers to 50 to 75°C, preferably 65 to 75°C.

6. The method according to claim 1, characterized in that The time for adding the zinc salt solution is controlled within 20-30 minutes.

7. The method according to claim 1, characterized in that The time for adding the sodium azotetrazolyl solution is controlled within 25-35 minutes.

8. The method according to claim 1, characterized in that The reaction time is 10-20 minutes.

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